HERO_ID,In_text,title,abstract,Tabs
2316157,Cooper 1983,Mortality In Employees Of Three Plants Which Produced Chromate Pigments,"A mortality study was conducted on 574 male workers from three facilities that produced chromate pigments. The cohort included workers who had been exposed to lead-chromate (7758976) for at least 6 months. Two of the facilities also had potential exposure to zinc-chromate (13530659). Additionally, one of these facilities had potential exposure to strontium-chromate (7789062) and barium-chromate (10294403). Causes of death were determined from company records or death certificates. Risk of death from lung cancer and other causes was described as a Standardized Mortality Ratio (SMR). Exposures to lead (7439921) and chromium (7440473) were estimated from company records and results of industrial hygiene surveys. Industrial hygiene surveys conducted at the time of the study showed that for the three facilities combined, the time weighted average concentrations exceeded OSHA limits for lead and chromium in nearly 50 percent of the samples collected. Company records and prior surveys indicated even higher concentrations. No attempt was made to correlate individual exposures with the mortality survey. The 246 males exposed to only lead-chromate were observed for 4768 person years. Twenty one deaths occurred, with 33.1 expected, giving an SMR of 63.5. The slight excess of lung cancer (3 observed and 2.3 expected), was not statistically significant. The 328 males exposed to lead-chromate and zinc-chromate with some exposures to strontium-chromate and barium-chromate were observed for 7457 person years. Sixty four deaths were observed (73.4 expected), giving an SMR of 87. There were 11 lung cancer deaths (4.8 expected), giving a statistically elevated SMR of 228. At one of the mixed exposure facilities, there were 5 stomach cancers (0.75 expected), giving a significantly elevated SMR of 667. The author concludes that exposure to zinc-chromate increases the risk of lung cancer and recommends investigation of the causes of the gastric cancers observed.","Mortality In Employees Of Three Plants Which Produced Chromate Pigments Abs: A mortality study was conducted on 574 male workers from three facilities that produced chromate pigments. The cohort included workers who had been exposed to lead-chromate (7758976) for at least 6 months. Two of the facilities also had potential exposure to zinc-chromate (13530659). Additionally, one of these facilities had potential exposure to strontium-chromate (7789062) and barium-chromate (10294403). Causes of death were determined from company records or death certificates. Risk of death from lung cancer and other causes was described as a Standardized Mortality Ratio (SMR). Exposures to lead (7439921) and chromium (7440473) were estimated from company records and results of industrial hygiene surveys. Industrial hygiene surveys conducted at the time of the study showed that for the three facilities combined, the time weighted average concentrations exceeded OSHA limits for lead and chromium in nearly 50 percent of the samples collected. Company records and prior surveys indicated even higher concentrations. No attempt was made to correlate individual exposures with the mortality survey. The 246 males exposed to only lead-chromate were observed for 4768 person years. Twenty one deaths occurred, with 33.1 expected, giving an SMR of 63.5. The slight excess of lung cancer (3 observed and 2.3 expected), was not statistically significant. The 328 males exposed to lead-chromate and zinc-chromate with some exposures to strontium-chromate and barium-chromate were observed for 7457 person years. Sixty four deaths were observed (73.4 expected), giving an SMR of 87. There were 11 lung cancer deaths (4.8 expected), giving a statistically elevated SMR of 228. At one of the mixed exposure facilities, there were 5 stomach cancers (0.75 expected), giving a significantly elevated SMR of 667. The author concludes that exposure to zinc-chromate increases the risk of lung cancer and recommends investigation of the causes of the gastric cancers observed."
2225622,Son et al. 2014,Amino acid digestibility in copra expellers and palm kernel expellers by growing pigs,"An experiment was conducted to determine the coefficient of ileal apparent digestibility (CIAD) and the coefficient of ileal standardized digestibility (CISD) of crude protein (CP) and amino acids (AA) in copra expellers (CE) and palm kernel expellers (PKE) by pigs. Six boars fitted with a T-cannula in the distal ileum with an initial body weight of 65.2 +/- 5.4 kg were individually housed in pens equipped with a feeder and a nipple drinker. A replicated 3 x 3 Latin square design was employed with 3 dietary treatments, 3 periods, and 6 animals. Two experimental diets were prepared to contain 400 g/kg of CE or PKE as the sole source of nitrogen. A nitrogen-free diet was also prepared to estimate the basal ileal endogenous loss of CP and AA. All diets contained 5 g/kg chromic oxide as an indigestible index. The CIAD of CP in CE was greater (P=0.002) than in PKE (0.294 vs. 0.051). The values for the CIAD of all indispensable AA except histidine and lysine in CE were also greater (P<0.05) than in PKE. The CISD of CP in CE was greater (P=0.014) than in PKE (0.676 vs. 0.528). The values for the CISD of all indispensable AA except histidine, isoleucine, and lysine in CE were greater (P<0.05) than in PKE. In conclusion, the digestibility of CP and most AA in CE was greater than in PKE. (C) 2013 Elsevier B.V. All rights reserved.","Amino acid digestibility in copra expellers and palm kernel expellers by growing pigs Abs: An experiment was conducted to determine the coefficient of ileal apparent digestibility (CIAD) and the coefficient of ileal standardized digestibility (CISD) of crude protein (CP) and amino acids (AA) in copra expellers (CE) and palm kernel expellers (PKE) by pigs. Six boars fitted with a T-cannula in the distal ileum with an initial body weight of 65.2 +/- 5.4 kg were individually housed in pens equipped with a feeder and a nipple drinker. A replicated 3 x 3 Latin square design was employed with 3 dietary treatments, 3 periods, and 6 animals. Two experimental diets were prepared to contain 400 g/kg of CE or PKE as the sole source of nitrogen. A nitrogen-free diet was also prepared to estimate the basal ileal endogenous loss of CP and AA. All diets contained 5 g/kg chromic oxide as an indigestible index. The CIAD of CP in CE was greater (P=0.002) than in PKE (0.294 vs. 0.051). The values for the CIAD of all indispensable AA except histidine and lysine in CE were also greater (P<0.05) than in PKE. The CISD of CP in CE was greater (P=0.014) than in PKE (0.676 vs. 0.528). The values for the CISD of all indispensable AA except histidine, isoleucine, and lysine in CE were greater (P<0.05) than in PKE. In conclusion, the digestibility of CP and most AA in CE was greater than in PKE. (C) 2013 Elsevier B.V. All rights reserved."
2225621,Wu et al. 2014,A novel Cr3+ turn-on probe based on naphthalimide and BINOL framework,"Naphthalimide and BINOL framework based fluorescent probe NP-B was rationally designed and synthesized. NP-B exhibited 'turn-on' fluorescence for Cr3+ and high selectivity over other metal ions. 1:1 binding mode between NP-B and Cr3+ was proposed and the mode was verified through MALDI-TOF mass spectrum. The detection limit was calculated to be 0.20 mu M, which indicated the good sensitivity for Cr3+. (C) 2013 Elsevier Ltd. All rights reserved.","A novel Cr3+ turn-on probe based on naphthalimide and BINOL framework Abs: Naphthalimide and BINOL framework based fluorescent probe NP-B was rationally designed and synthesized. NP-B exhibited 'turn-on' fluorescence for Cr3+ and high selectivity over other metal ions. 1:1 binding mode between NP-B and Cr3+ was proposed and the mode was verified through MALDI-TOF mass spectrum. The detection limit was calculated to be 0.20 mu M, which indicated the good sensitivity for Cr3+. (C) 2013 Elsevier Ltd. All rights reserved."
2225620,Tadini et al. 2014,Fractionation of Aquatic Humic Substances and Dynamic of Chromium Species in an Aquatic Body Influenced by Sugarcane Cultivation,"This study had as main objective to evaluate the influence of AHS obtained from an area under sugarcane cultivation on the dynamics of chromium species (Cr(III) and Cr(VI)). Was studied complexing capacity (CC) with the AHS of chromium species and these were characterized using UV/Vis spectrophotometry, molecular fluorescence, elemental analysis and infrared. AHS with and without fractionation showed a greater aromaticity degree and a predominance of humic acids, and the E-4/E-6 and E-2/E-4 ratios suggested aromatic rings and a greater contribution from plants, which indicates lignin structures. The highest CCs were observed for the AHS fractionated, being fraction with molecular-size < 10 kDa and 10-30 kDa showed the highest ability to complex Cr(III) and Cr(VI) ions, respectively. These results are corroborating with C/H/N and UV/Vis data, where we can conclude that the AHS without fractionation had the greatest aromaticity and a predominance of humic acids in their structure.","Fractionation of Aquatic Humic Substances and Dynamic of Chromium Species in an Aquatic Body Influenced by Sugarcane Cultivation Abs: This study had as main objective to evaluate the influence of AHS obtained from an area under sugarcane cultivation on the dynamics of chromium species (Cr(III) and Cr(VI)). Was studied complexing capacity (CC) with the AHS of chromium species and these were characterized using UV/Vis spectrophotometry, molecular fluorescence, elemental analysis and infrared. AHS with and without fractionation showed a greater aromaticity degree and a predominance of humic acids, and the E-4/E-6 and E-2/E-4 ratios suggested aromatic rings and a greater contribution from plants, which indicates lignin structures. The highest CCs were observed for the AHS fractionated, being fraction with molecular-size < 10 kDa and 10-30 kDa showed the highest ability to complex Cr(III) and Cr(VI) ions, respectively. These results are corroborating with C/H/N and UV/Vis data, where we can conclude that the AHS without fractionation had the greatest aromaticity and a predominance of humic acids in their structure."
2225619,Wang et al. 2013,Reduction of Cr(VI) in aqueous solution with DC diaphragm glow discharge,"This paper investigated the reduction of Cr(VI) in aqueous solution with direct current diaphragm glow discharge (DGD). The glow discharge sustained around the hole on a quartz tube which divided the electrolyte cell into two parts. The reduction efficiencies of Cr(VI) under different applied voltages, initial conductivities, hole diameters, hole numbers, initial pH values and initial concentrations were systematically studied. The results showed that the reduction efficiency of Cr(VI) increased with the increase of applied voltage, initial conductivity, hole diameter and hole number. The different initial pH values showed less effects on the reduction of Cr(VI). The reduction efficiency decreased with the increasing initial concentration. In addition, the simultaneous reduction of Cr(VI) and decolorization of acid orange (AO) with DGD were also fulfilled. Furthermore, the energy efficiency for Cr(VI) reduction with DGD was calculated and compared with those in photocatalysis and other glow discharge reactor. (C) 2013 Elsevier Ltd. All rights reserved.","Reduction of Cr(VI) in aqueous solution with DC diaphragm glow discharge Abs: This paper investigated the reduction of Cr(VI) in aqueous solution with direct current diaphragm glow discharge (DGD). The glow discharge sustained around the hole on a quartz tube which divided the electrolyte cell into two parts. The reduction efficiencies of Cr(VI) under different applied voltages, initial conductivities, hole diameters, hole numbers, initial pH values and initial concentrations were systematically studied. The results showed that the reduction efficiency of Cr(VI) increased with the increase of applied voltage, initial conductivity, hole diameter and hole number. The different initial pH values showed less effects on the reduction of Cr(VI). The reduction efficiency decreased with the increasing initial concentration. In addition, the simultaneous reduction of Cr(VI) and decolorization of acid orange (AO) with DGD were also fulfilled. Furthermore, the energy efficiency for Cr(VI) reduction with DGD was calculated and compared with those in photocatalysis and other glow discharge reactor. (C) 2013 Elsevier Ltd. All rights reserved."
2225618,Oladoja et al. 2013,Iron incorporated rice husk silica as a sorbent for hexavalent chromium attenuation in aqueous system,"An environmentally benign metal oxide, Fe, was incorporated into silica derived from rice husk via the sol gel route and the physiognomies of both the modified (IRS) and raw rice husk derived silica (RHS) were studied via FTIR and XRD analysis and pH(PZC) and surface area determinations. The stability of the Fe incorporated into the silica matrix, determined via the toxicity characteristic leaching procedure, showed that the integrity of the sorbent was intact only in basic medium but got vitiated in acidic medium. The sorption process conformed to the pseudo second order model than reversible first order and pseudo first order kinetic models and the rate of sorption of Cr(VI) onto either sorbents was determined by film diffusion. Process variables optimization showed that the amount of Cr(VI) removed per gram of sorbent reduced with increase in initial solution pH and the negative impact of the anionic interference was more in the presence of SO32- than NO32- and Cl-. The predicted Langmuir monolayer sorption capacity (mg/g) of the IRS (63.69) was higher than that of the RHS (61.35). The value of the mean free energy (kJ/mol) of sorption, obtained for IRS (267.26) and RHS (100.00), and the significant changes in the peak positions of specific functional groups on the Cr(VI) laden sorbents showed that chemisorption was the dominant mechanism of Cr(VI) uptake. (C) 2013 The Institution of Chemical Engineers. Published by Elsevier B.V. All rights reserved.","Iron incorporated rice husk silica as a sorbent for hexavalent chromium attenuation in aqueous system Abs: An environmentally benign metal oxide, Fe, was incorporated into silica derived from rice husk via the sol gel route and the physiognomies of both the modified (IRS) and raw rice husk derived silica (RHS) were studied via FTIR and XRD analysis and pH(PZC) and surface area determinations. The stability of the Fe incorporated into the silica matrix, determined via the toxicity characteristic leaching procedure, showed that the integrity of the sorbent was intact only in basic medium but got vitiated in acidic medium. The sorption process conformed to the pseudo second order model than reversible first order and pseudo first order kinetic models and the rate of sorption of Cr(VI) onto either sorbents was determined by film diffusion. Process variables optimization showed that the amount of Cr(VI) removed per gram of sorbent reduced with increase in initial solution pH and the negative impact of the anionic interference was more in the presence of SO32- than NO32- and Cl-. The predicted Langmuir monolayer sorption capacity (mg/g) of the IRS (63.69) was higher than that of the RHS (61.35). The value of the mean free energy (kJ/mol) of sorption, obtained for IRS (267.26) and RHS (100.00), and the significant changes in the peak positions of specific functional groups on the Cr(VI) laden sorbents showed that chemisorption was the dominant mechanism of Cr(VI) uptake. (C) 2013 The Institution of Chemical Engineers. Published by Elsevier B.V. All rights reserved."
2225617,Lu et al. 2014,ZVI/PANI/ATP composite by static polymerization as adsorbent for removal of Cr(VI),"Much work is devoted to studying the application of zero valent iron (ZVI) in permeable reactive barriers (PRBs) which is used to remove heavy metal ions in low concentrations. However, to date, fewer studies have reported the utilization of organic conductive polymers to cover the surface of ZVI particles for improving adsorption capacity. A Polyaniline/Attapulgite (PANI/ATP) composite was well prepared in a solution of HNO3 by static polymerization, in which the ZVI particles were successfully dispersed in a highly viscous PANI/ATP composite. Also, the effect of the anticorrosive properties and electrical conductivity of PANI on the surface of the ZVI particles for the removal of Cr(VI) was studied, solving the problem of poor-dispersion and easy-corrosion of the ZVI particles. The results show that the mass ratio of An, ZVI and ATP in this material was 1 : 4 : 4 and the adsorption capacity achieved for the removal of Cr(VI) from water was 86.56 mg g(-1), thus the material shows great potential as an efficient adsorbent for water pollution arising from heavy metal ions on a large scale.","ZVI PANI ATP composite by static polymerization as adsorbent for removal of Cr(VI) Abs: Much work is devoted to studying the application of zero valent iron (ZVI) in permeable reactive barriers (PRBs) which is used to remove heavy metal ions in low concentrations. However, to date, fewer studies have reported the utilization of organic conductive polymers to cover the surface of ZVI particles for improving adsorption capacity. A Polyaniline/Attapulgite (PANI/ATP) composite was well prepared in a solution of HNO3 by static polymerization, in which the ZVI particles were successfully dispersed in a highly viscous PANI/ATP composite. Also, the effect of the anticorrosive properties and electrical conductivity of PANI on the surface of the ZVI particles for the removal of Cr(VI) was studied, solving the problem of poor-dispersion and easy-corrosion of the ZVI particles. The results show that the mass ratio of An, ZVI and ATP in this material was 1 : 4 : 4 and the adsorption capacity achieved for the removal of Cr(VI) from water was 86.56 mg g(-1), thus the material shows great potential as an efficient adsorbent for water pollution arising from heavy metal ions on a large scale."
2225616,Yue et al. 2013,Characteristics of Amine Surfactant Modified Peanut Shell and Its Sorption Property for Cr(VI),"Modified peanut shell (MPS) was prepared by amination reaction with peanut shell (PS) as the starting material. The sorption of Cr(VI) oxyanions on MPS in static and column tests were investigated. In addition, the sorption isotherm and kinetic models were applied to confirm the sorption capacity and the sorption mechanisms. BET surface area analysis showed the physicochemical characteristics of the samples. The results of zeta potential, Fourier transform infrared (FT-IR) and Raman spectra analysis illustrated that chemical adsorption and ion exchange are the potential sorption mechanism. The static sorption test showed that the maximum sorption capacity (q(max)) of MPS for Cr(VI) increased with temperature, which indicated that the Cr(VI) sorption process was endothermic. The saturated sorption capacity of Cr(VI) in the column sorption test was 138.34 mg.g(-1), which accounted for 93.9% of the qmax at 25 degrees C. The regeneration capacity of MPS was evaluated using HCl solution as an eluent. The high regeneration efficiency (82.6%) validated the dominance of the ion exchange mechanism in the Cr(VI) sorption process with Cl-ions displacing Cr(VI) oxyanion on MPS. The Langmuir isotherm model showed a higher correlation coefficient than the other adsorption isotherm models. And in the kinetic study, a pseudo-second-order model fit the data best.","Characteristics of Amine Surfactant Modified Peanut Shell and Its Sorption Property for Cr(VI) Abs: Modified peanut shell (MPS) was prepared by amination reaction with peanut shell (PS) as the starting material. The sorption of Cr(VI) oxyanions on MPS in static and column tests were investigated. In addition, the sorption isotherm and kinetic models were applied to confirm the sorption capacity and the sorption mechanisms. BET surface area analysis showed the physicochemical characteristics of the samples. The results of zeta potential, Fourier transform infrared (FT-IR) and Raman spectra analysis illustrated that chemical adsorption and ion exchange are the potential sorption mechanism. The static sorption test showed that the maximum sorption capacity (q(max)) of MPS for Cr(VI) increased with temperature, which indicated that the Cr(VI) sorption process was endothermic. The saturated sorption capacity of Cr(VI) in the column sorption test was 138.34 mg.g(-1), which accounted for 93.9% of the qmax at 25 degrees C. The regeneration capacity of MPS was evaluated using HCl solution as an eluent. The high regeneration efficiency (82.6%) validated the dominance of the ion exchange mechanism in the Cr(VI) sorption process with Cl-ions displacing Cr(VI) oxyanion on MPS. The Langmuir isotherm model showed a higher correlation coefficient than the other adsorption isotherm models. And in the kinetic study, a pseudo-second-order model fit the data best."
2225615,Faghihian and  Naghavi 2014,Synthesis of Amine-Functionalized MCM-41 and MCM-48 for Removal of Heavy Metal Ions from Aqueous Solutions,"In this research amino functional mesoporous MCM-41 and MCM-48 materials were prepared in an attempt to develop efficient adsorbents for removal of heavy metals from aqueous solutions. The adsorbents were characterized by XRD, FTIR, and TG-DTG techniques. The synthesized adsorbents were used for the removal of Cu(II), Co(II), Cd(II), and Pb(II) from aqueous solutions for the first time, and the influence of some effective parameters including concentration, initial pH, contact time, and temperature on the sorption process was studied and optimized. Significant adsorption capacities were obtained at low concentrations. The kinetic studies showed that the adsorption process was fast and more than 90% of equilibrium capacity was achieved within 60min. Experimental kinetic data was well fitted with the pseudo-second-order kinetic model. Thermodynamic parameters computed from the experimental data showed that the adsorption was endothermic and spontaneous.","Synthesis of Amine-Functionalized MCM-41 and MCM-48 for Removal of Heavy Metal Ions from Aqueous Solutions Abs: In this research amino functional mesoporous MCM-41 and MCM-48 materials were prepared in an attempt to develop efficient adsorbents for removal of heavy metals from aqueous solutions. The adsorbents were characterized by XRD, FTIR, and TG-DTG techniques. The synthesized adsorbents were used for the removal of Cu(II), Co(II), Cd(II), and Pb(II) from aqueous solutions for the first time, and the influence of some effective parameters including concentration, initial pH, contact time, and temperature on the sorption process was studied and optimized. Significant adsorption capacities were obtained at low concentrations. The kinetic studies showed that the adsorption process was fast and more than 90% of equilibrium capacity was achieved within 60min. Experimental kinetic data was well fitted with the pseudo-second-order kinetic model. Thermodynamic parameters computed from the experimental data showed that the adsorption was endothermic and spontaneous."
2225614,Lalueza et al. 2014,REMOVAL OF CHROMIUM (III) FROM TANNERY WASTEWATERS WITH ACIDOPHILIC FUNGI,"Conventional methods for chromium removal from industrial effluents may be limited by technological or economical constraints, especially when they are applied to dilute metal solutions. Thus, biotechnological processes, which are efficient at low metal concentrations and require the use of fewer chemicals, may play an important role. The chromium recovery proposed here is based on the specific uptake of this metal by acidophilic fungi. Fifty acidophilic fungal isolates from the Rio Tinto basin, an extreme acidic environment, were tested. Most of them were resistant to Cr(III) and Cr(VI) solutions at concentrations up to 10 mmol/L. The influence of different experimental conditions was evaluated (medium concentration, kinetics, requirement of induction etc.). Fungal isolate 143 was able to remove 63% of Cr(III) at 0.1 mmol/L, 74% at 1 mmol/L and 21% at 10 mmol/L. These are the best Cr(III)-fungal-uptake results at acidic pH described in the literature so far. It should be possible to use these acidophilic fungi, for example in tannery wastewater, as they can resist chromium concentrations and pH values found in these effluents (between 6.5-7.5 mmol/L Cr (III) and pH as low as 3-4).","REMOVAL OF CHROMIUM (III) FROM TANNERY WASTEWATERS WITH ACIDOPHILIC FUNGI Abs: Conventional methods for chromium removal from industrial effluents may be limited by technological or economical constraints, especially when they are applied to dilute metal solutions. Thus, biotechnological processes, which are efficient at low metal concentrations and require the use of fewer chemicals, may play an important role. The chromium recovery proposed here is based on the specific uptake of this metal by acidophilic fungi. Fifty acidophilic fungal isolates from the Rio Tinto basin, an extreme acidic environment, were tested. Most of them were resistant to Cr(III) and Cr(VI) solutions at concentrations up to 10 mmol/L. The influence of different experimental conditions was evaluated (medium concentration, kinetics, requirement of induction etc.). Fungal isolate 143 was able to remove 63% of Cr(III) at 0.1 mmol/L, 74% at 1 mmol/L and 21% at 10 mmol/L. These are the best Cr(III)-fungal-uptake results at acidic pH described in the literature so far. It should be possible to use these acidophilic fungi, for example in tannery wastewater, as they can resist chromium concentrations and pH values found in these effluents (between 6.5-7.5 mmol/L Cr (III) and pH as low as 3-4)."
2225603,Nataraj et al. 2013,Synthesis and Characterization of Novel Chromium-Free Nickel Alloy Electrode Materials,,Synthesis and Characterization of Novel Chromium-Free Nickel Alloy Electrode Materials Abs: 
2225602,Iyayi et al. 2013,True phosphorus digestibility of black-eyed pea and peanut flour without or with phytase supplementation in broiler chickens,,True phosphorus digestibility of black-eyed pea and peanut flour without or with phytase supplementation in broiler chickens Abs: 
2225601,Liu et al. 2013,Phosphorus digestibility response of broiler chickens to dietary calcium-to-phosphorus ratios,,Phosphorus digestibility response of broiler chickens to dietary calcium-to-phosphorus ratios Abs: 
2225600,Nguyen et al. 2013,Removal of chromium(VI) from the leachate of electronic scrap using non-ionic Amberlite XAD-7HP resin,,Removal of chromium(VI) from the leachate of electronic scrap using non-ionic Amberlite XAD-7HP resin Abs: 
2225599,Zhang et al. 2013,Facile synthesis L-cysteine capped CdS:Eu quantum dots and their Hg2+ sensitive properties,,Facile synthesis L-cysteine capped CdS:Eu quantum dots and their Hg2+ sensitive properties Abs: 
2225598,Xue and  Van Ooij 2013,Corrosion performance improvement of hot-dipped galvanized (HDG) steels by electro-deposition of epoxy-resin-ester modified bis-[tri-ethoxy-silyl] ethane (BTSE) coatings,,Corrosion performance improvement of hot-dipped galvanized (HDG) steels by electro-deposition of epoxy-resin-ester modified bis-[tri-ethoxy-silyl] ethane (BTSE) coatings Abs: 
2225597,Uma et al. 2013,Equilibrium and kinetic studies for removal of malachite green from aqueous solution by a low cost activated carbon,,Equilibrium and kinetic studies for removal of malachite green from aqueous solution by a low cost activated carbon Abs: 
2225596,Seo et al. 2013,Remediation of Chromium-Contaminated Water Using Biogenic Nano-Sized Materials and Metal-Reducing Bacteria,,Remediation of Chromium-Contaminated Water Using Biogenic Nano-Sized Materials and Metal-Reducing Bacteria Abs: 
2225595,Zhu et al. 2013,"Response of Pacific White Shrimp, Litopenaeus vannamei, to Three Sources of Solvent Extracted Soybean Meal",,"Response of Pacific White Shrimp, Litopenaeus vannamei, to Three Sources of Solvent Extracted Soybean Meal Abs: "
2225594,Verbinnen et al. 2013,Heating Temperature Dependence of Cr(III) Oxidation in the Presence of Alkali and Alkaline Earth Salts and Subsequent Cr(VI) Leaching Behavior,,Heating Temperature Dependence of Cr(III) Oxidation in the Presence of Alkali and Alkaline Earth Salts and Subsequent Cr(VI) Leaching Behavior Abs: 
2225593,Zhang et al. 2013,Bioinspired Multifunctional Foam with Self-Cleaning and Oil/Water Separation,,Bioinspired Multifunctional Foam with Self-Cleaning and Oil/Water Separation Abs: 
2225591,Cho et al. 2013,"Effects of fermented grains as raw cereal substitutes on growth performance, nutrient digestibility, blood profiles, and fecal noxious gas emission in growing pigs",,"Effects of fermented grains as raw cereal substitutes on growth performance, nutrient digestibility, blood profiles, and fecal noxious gas emission in growing pigs Abs: "
2225590,Seidel et al. 2013,National and California treatment costs to comply with potential hexavalent chromium MCLs,,National and California treatment costs to comply with potential hexavalent chromium MCLs Abs: 
2225589,Seidel and  Corwin 2013,Total chromium and hexavalent chromium occurrence analysis,,Total chromium and hexavalent chromium occurrence analysis Abs: 
2225586,Krika et al. 2013,Adsorptive removal of cadmium (II) using P-oceanica biomass: effect of NaCl concentration on equilibrium and kinetic parameters,,Adsorptive removal of cadmium (II) using P-oceanica biomass: effect of NaCl concentration on equilibrium and kinetic parameters Abs: 
2225585,Ma et al. 2013,Study of an environment-friendly surface pretreatment of ABS-polycarbonate surface for adhesion improvement,,Study of an environment-friendly surface pretreatment of ABS-polycarbonate surface for adhesion improvement Abs: 
2225584,Gao et al. 2013,Preparation of Arsenate Anion Surface-Imprinted Material IIP-PDMC/SiO2 and Study on Its Ion Recognition Property,,Preparation of Arsenate Anion Surface-Imprinted Material IIP-PDMC/SiO2 and Study on Its Ion Recognition Property Abs: 
2225583,Prim et al. 2013,"Pink ceramic pigments based on chromium doped M(Al2-xCrx)O-4, M = Mg, Zn, normal spinel",,"Pink ceramic pigments based on chromium doped M(Al2-xCrx)O-4, M = Mg, Zn, normal spinel Abs: "
2225581,Zhang et al. 2014,Ultrasound-Enhanced Adsorption of Chromium(VI) on Fe3O4 Magnetic Particles. 53,,Ultrasound-Enhanced Adsorption of Chromium(VI) on Fe3O4 Magnetic Particles. 53 Abs: 
2225580,Yang et al. 2014,Oxidation of Cr(III)-citrate/tartrate complexes by delta-MnO2: Production of Cr(VI) and its impact factors. 213,,Oxidation of Cr(III)-citrate/tartrate complexes by delta-MnO2: Production of Cr(VI) and its impact factors. 213 Abs: 
2225579,Srivastava and  YC 2014,Synthesis and Characterization of Fe3O4@n-SiO2 Nanoparticles from an Agrowaste Material and Its Application for the Removal of Cr(VI) from Aqueous Solutions. 225,,Synthesis and Characterization of Fe3O4@n-SiO2 Nanoparticles from an Agrowaste Material and Its Application for the Removal of Cr(VI) from Aqueous Solutions. 225 Abs: 
2225578,Qian et al. 2014,Efficient reduction of Cr(VI) in groundwater by a hybrid electro-Pd process. 48,,Efficient reduction of Cr(VI) in groundwater by a hybrid electro-Pd process. 48 Abs: 
2225577,Lei and  IH 2014,"Effect of Phaffia rhodozyma on performance, nutrient digestibility, blood characteristics, and meat quality in finishing pigs. 92",,"Effect of Phaffia rhodozyma on performance, nutrient digestibility, blood characteristics, and meat quality in finishing pigs. 92 Abs: "
2225576,Berger and  Frei 2014,The fate of chromium during tropical weathering: A laterite profile from Central Madagascar. 213,,The fate of chromium during tropical weathering: A laterite profile from Central Madagascar. 213 Abs: 
2225575,Muthusamy et al. 2014,"Biosorption of Cr(VI) and Zn(II) ions from aqueous solution onto the solid biodiesel waste residue: mechanistic, kinetic and thermodynamic studies","In this present study, the biosorption of Cr(VI) and Zn(II) ions from synthetic aqueous solution on defatted J atropha oil cake (DJOC) was investigated. The effect of various process parameters such as the initial pH, adsorbent dosage, initial metal ion concentration and contact time has been studied in batch-stirred experiments. Maximum removal of Cr(VI) and Zn(II) ions in aqueous solution was observed at pH 2.0 and pH. 5.0, respectively. The removal efficiency of Cr(VI) and Zn(II) ions from the aqueous solution was found to be 72.56 and 79.81 %, respectively, for initial metal ion concentration of 500 mg/L at 6 g/L dosage concentration. The biosorbent was characterized by Fourier transform infrared, scanning electron microscopy and zero point charge. Equilibrium data were fitted to the Langmuir, Freundlich, Temkin and Dubinin-Radushkevich isotherm models and the best fit is found to be with the Freundlich isotherm for both Cr(VI) and Zn(II) metal ions. The kinetic data obtained at different metal ion concentration have been analysed using the pseudo-first-order, pseudo-second-order and intraparticle diffusion models and were found to follow the pseudo-second-order kinetic model. The values of mass transfer diffusion coefficients (D e) were determined by Boyd model and compared with literature values. Various thermodynamic parameters, such as ?G°, ?H° and ?S°, were analysed using the equilibrium constant values (K e) obtained from experimental data at different temperatures. The results showed that biosorption of Cr(VI) and Zn(II) ions onto the DJOC system is more spontaneous and exothermic in nature. The results indicate that DJOC was shown to be a promising adsorbent for the removal of Cr(VI) and Zn(II) ions from aqueous solution.","Biosorption of Cr(VI) and Zn(II) ions from aqueous solution onto the solid biodiesel waste residue: mechanistic, kinetic and thermodynamic studies Abs: In this present study, the biosorption of Cr(VI) and Zn(II) ions from synthetic aqueous solution on defatted J atropha oil cake (DJOC) was investigated. The effect of various process parameters such as the initial pH, adsorbent dosage, initial metal ion concentration and contact time has been studied in batch-stirred experiments. Maximum removal of Cr(VI) and Zn(II) ions in aqueous solution was observed at pH 2.0 and pH. 5.0, respectively. The removal efficiency of Cr(VI) and Zn(II) ions from the aqueous solution was found to be 72.56 and 79.81 %, respectively, for initial metal ion concentration of 500 mg/L at 6 g/L dosage concentration. The biosorbent was characterized by Fourier transform infrared, scanning electron microscopy and zero point charge. Equilibrium data were fitted to the Langmuir, Freundlich, Temkin and Dubinin-Radushkevich isotherm models and the best fit is found to be with the Freundlich isotherm for both Cr(VI) and Zn(II) metal ions. The kinetic data obtained at different metal ion concentration have been analysed using the pseudo-first-order, pseudo-second-order and intraparticle diffusion models and were found to follow the pseudo-second-order kinetic model. The values of mass transfer diffusion coefficients (D e) were determined by Boyd model and compared with literature values. Various thermodynamic parameters, such as ?G°, ?H° and ?S°, were analysed using the equilibrium constant values (K e) obtained from experimental data at different temperatures. The results showed that biosorption of Cr(VI) and Zn(II) ions onto the DJOC system is more spontaneous and exothermic in nature. The results indicate that DJOC was shown to be a promising adsorbent for the removal of Cr(VI) and Zn(II) ions from aqueous solution."
2225574,Li et al. 2013,"A Cationic Metal-Organic Framework Consisting of Nanoscale Cages: Capture, Separation, and Luminescent Probing of Cr 2 O 7 2? through a Single-Crystal to Single-Crystal Process",,"A Cationic Metal-Organic Framework Consisting of Nanoscale Cages: Capture, Separation, and Luminescent Probing of Cr 2 O 7 2? through a Single-Crystal to Single-Crystal Process Abs: "
2225570,Schellenger and  Larese-Casanova 2013,Oxygen Isotope Indicators of Selenate Reaction with Fe(II) and Fe(III) Hydroxides,,Oxygen Isotope Indicators of Selenate Reaction with Fe(II) and Fe(III) Hydroxides Abs: 
2225569,Velazquez-Pena et al. 2013,Azo dyes as electron transfer mediators in the electrochemical reduction of Cr(VI) using boron-doped diamond electrodes,,Azo dyes as electron transfer mediators in the electrochemical reduction of Cr(VI) using boron-doped diamond electrodes Abs: 
2225568,Teymouri et al. 2013,BIOSORPTION STUDIES ON NACL-MODIFIED CERATOPHYLLUM DEMERSUM: REMOVAL OF TOXIC CHROMIUM FROM AQUEOUS SOLUTION,,BIOSORPTION STUDIES ON NACL-MODIFIED CERATOPHYLLUM DEMERSUM: REMOVAL OF TOXIC CHROMIUM FROM AQUEOUS SOLUTION Abs: 
2225567,Santamaria-Perez et al. 2013,"Phase Behavior of Ag2CrO4 under Compression: Structural, Vibrational, and Optical Properties",,"Phase Behavior of Ag2CrO4 under Compression: Structural, Vibrational, and Optical Properties Abs: "
2225566,Nie et al. 2013,Effect of anodizing treatment on the very high cycle fatigue behavior of 2A12-T4 aluminum alloy,,Effect of anodizing treatment on the very high cycle fatigue behavior of 2A12-T4 aluminum alloy Abs: 
2225565,Liu et al. 2013,Photoreduction of Cr(VI) from acidic aqueous solution using TiO2-impregnated glutaraldehyde-crosslinked alginate beads and the effects of Fe(III) ions,,Photoreduction of Cr(VI) from acidic aqueous solution using TiO2-impregnated glutaraldehyde-crosslinked alginate beads and the effects of Fe(III) ions Abs: 
2225564,Xu et al. 2013,Nitrate adsorption by stratified wheat straw resin in lab-scale columns,,Nitrate adsorption by stratified wheat straw resin in lab-scale columns Abs: 
2225563,Dadvar et al. 2013,A study on the kinetics of 2-chloroethyl ethyl sulfide adsorption onto nanocomposite activated carbon nanofibers containing metal oxide nanoparticles,,A study on the kinetics of 2-chloroethyl ethyl sulfide adsorption onto nanocomposite activated carbon nanofibers containing metal oxide nanoparticles Abs: 
2225562,Ge et al. 2013,Comparative evaluations on bio-treatment of hexavalent chromate by resting cells of Pseudochrobactrum sp and Proteus sp in wastewater,,Comparative evaluations on bio-treatment of hexavalent chromate by resting cells of Pseudochrobactrum sp and Proteus sp in wastewater Abs: 
2225561,Geier et al. 2013,"Occupational contact allergy in bricklayers, tile setters etc. Current spectrum of sensitization and recent time trends",,"Occupational contact allergy in bricklayers, tile setters etc. Current spectrum of sensitization and recent time trends Abs: "
2225560,Dedkova et al. 2013,Consecutive sorption of molybdenum(VI) and chromium(VI) from a single sample onto fiber materials filled with an anion exchanger and their solid-phase determination with phenylfluorone and diphenylcarbazide,,Consecutive sorption of molybdenum(VI) and chromium(VI) from a single sample onto fiber materials filled with an anion exchanger and their solid-phase determination with phenylfluorone and diphenylcarbazide Abs: 
2225559,Hassan 2013,Effect of halides addition on the ligand field of chromium in alkali borate glasses,,Effect of halides addition on the ligand field of chromium in alkali borate glasses Abs: 
2225558,Xie et al. 2013,Walnut shell-based activated carbon with excellent copper (II) adsorption and lower chromium (VI) removal prepared by acid-base modification,,Walnut shell-based activated carbon with excellent copper (II) adsorption and lower chromium (VI) removal prepared by acid-base modification Abs: 
2225557,Murugesan et al. 2013,Removal of chromium (VI) from aqueous solution using chemically modified corncorb-activated carbon: Equilibrium and kinetic studies,,Removal of chromium (VI) from aqueous solution using chemically modified corncorb-activated carbon: Equilibrium and kinetic studies Abs: 
2225556,Mishra et al. 2013,Removal of zinc ions from wastewater using industrial waste sludge: A novel approach,,Removal of zinc ions from wastewater using industrial waste sludge: A novel approach Abs: 
2225555,Zhao et al. 2013,Enhanced photo-reduction and removal of Cr(VI) on reduced graphene oxide decorated with TiO2 nanoparticles,"Reduced graphene oxide decorated with TiO2 nanoparticles (TiO2-RGO) was synthesized and characterized by scanning and transmission electron microscopy, powder X-ray diffraction, ultraviolet-visible spectroscopy, photoluminescence excitation and emission spectroscopy, and X-ray photoelectron spectroscopy. Photo-reduction and removal of Cr(VI) from an aqueous solution using the material were investigated under visible light irradiation. Compared to pure TiO2, the TiO2-RGO exhibited an improved photocatalytic performance in the reduction of Cr(VI) under visible light irradiation, with a maximum removal of 86.5% vs 54.2% due to the increased light absorption intensity and wavelength range as well as the reduction in electron-hole pair recombination in TiO2 with the addition of RGO. The adsorption and photocatalytic reduction of Cr(VI) decreased with increasing pH, due to the decrease in the electrostatic attraction between anionic Cr(VI) and TiO2-RGO and the decrease in the thermodynamic driving force of Cr(VI) reduction to Cr(III).","Enhanced photo-reduction and removal of Cr(VI) on reduced graphene oxide decorated with TiO2 nanoparticles Abs: Reduced graphene oxide decorated with TiO2 nanoparticles (TiO2-RGO) was synthesized and characterized by scanning and transmission electron microscopy, powder X-ray diffraction, ultraviolet-visible spectroscopy, photoluminescence excitation and emission spectroscopy, and X-ray photoelectron spectroscopy. Photo-reduction and removal of Cr(VI) from an aqueous solution using the material were investigated under visible light irradiation. Compared to pure TiO2, the TiO2-RGO exhibited an improved photocatalytic performance in the reduction of Cr(VI) under visible light irradiation, with a maximum removal of 86.5% vs 54.2% due to the increased light absorption intensity and wavelength range as well as the reduction in electron-hole pair recombination in TiO2 with the addition of RGO. The adsorption and photocatalytic reduction of Cr(VI) decreased with increasing pH, due to the decrease in the electrostatic attraction between anionic Cr(VI) and TiO2-RGO and the decrease in the thermodynamic driving force of Cr(VI) reduction to Cr(III)."
2225554,Takeda et al. 2013,Magnetic frustration effects in the new colossal magnetoresistance oxide NaCr2O4,,Magnetic frustration effects in the new colossal magnetoresistance oxide NaCr2O4 Abs: 
2225553,Chilomer et al. 2013,The influence of lupin seed germination on the chemical composition and standardized ileal digestibility of protein and amino acids in pigs,,The influence of lupin seed germination on the chemical composition and standardized ileal digestibility of protein and amino acids in pigs Abs: 
2225552,Langone et al. 2013,SERPENTINITE-WATER INTERACTION AND CHROMIUM(VI) RELEASE IN SPRING WATERS: EXAMPLES FROM TUSCAN OPHIOLITES,,SERPENTINITE-WATER INTERACTION AND CHROMIUM(VI) RELEASE IN SPRING WATERS: EXAMPLES FROM TUSCAN OPHIOLITES Abs: 
2225551,Silva et al. 2013,Digestibility of feed ingredients for the striped surubim Pseudoplatystoma reticulatum,,Digestibility of feed ingredients for the striped surubim Pseudoplatystoma reticulatum Abs: 
2225550,Zhang et al. 2013,Signal transduction disturbance related to hepatocarcinogenesis in mouse by prolonged exposure to Nanjing drinking water,,Signal transduction disturbance related to hepatocarcinogenesis in mouse by prolonged exposure to Nanjing drinking water Abs: 
2225549,Zhang et al. 2013,Removal of Cr(VI) with Cogeneration of Electricity by an Alkaline Fuel Cell Reactor,,Removal of Cr(VI) with Cogeneration of Electricity by an Alkaline Fuel Cell Reactor Abs: 
2225548,He et al. 2013,Photocatalytic Reduction of Cr(VI) in an Aqueous Suspension of Surface-Fluorinated Anatase TiO2 Nanosheets with Exposed {001} Facets,,Photocatalytic Reduction of Cr(VI) in an Aqueous Suspension of Surface-Fluorinated Anatase TiO2 Nanosheets with Exposed {001} Facets Abs: 
2225547,Martinez-Trujillo et al. 2013,Morphogenic responses of the roots of Arabidopsis thaliana (Magnoliophyta: Brassicales) to Cr(VI) stress,,Morphogenic responses of the roots of Arabidopsis thaliana (Magnoliophyta: Brassicales) to Cr(VI) stress Abs: 
2225546,Duputel et al. 2013,Citrate adsorption can decrease soluble phosphate concentration in soils: Results of theoretical modeling,,Citrate adsorption can decrease soluble phosphate concentration in soils: Results of theoretical modeling Abs: 
2225545,Cederkvist et al. 2013,Behaviour of chromium(VI) in stormwater soil infiltration systems,,Behaviour of chromium(VI) in stormwater soil infiltration systems Abs: 
2225544,Saha et al. 2013,Kinetics of micellar catalysis on oxidation of p-anisaldehyde to p-anisic acid in aqueous medium at room temperature,,Kinetics of micellar catalysis on oxidation of p-anisaldehyde to p-anisic acid in aqueous medium at room temperature Abs: 
2225543,Wang et al. 2013,Biotreatment of chromite ore processing residue by Pannonibacter phragmitetus BB,,Biotreatment of chromite ore processing residue by Pannonibacter phragmitetus BB Abs: 
2225542,Margon et al. 2013,Soil microbial biomass influence on strontium availability in mine soil,,Soil microbial biomass influence on strontium availability in mine soil Abs: 
2225541,Komsta et al. 2013,EXPLORING HIDDEN TRENDS IN CLASSIC AND MICELLAR THIN-LAYER CHROMATOGRAPHIC RETENTION OF MODEL COMPOUNDS BY CHEMOMETRIC METHODS,,EXPLORING HIDDEN TRENDS IN CLASSIC AND MICELLAR THIN-LAYER CHROMATOGRAPHIC RETENTION OF MODEL COMPOUNDS BY CHEMOMETRIC METHODS Abs: 
2225540,Jiahong et al. 2013,Adsorption and Desorption Behavior of Tannic Acid in Aqueous Solution on Polyaniline Adsorbent,,Adsorption and Desorption Behavior of Tannic Acid in Aqueous Solution on Polyaniline Adsorbent Abs: 
2225539,Tavallali et al. 2013,Preconcentration and speciation of Cr(III) and Cr(VI) in water and soil samples by spectrometric detection via use of nanosized alumina-coated magnetite solid phase,,Preconcentration and speciation of Cr(III) and Cr(VI) in water and soil samples by spectrometric detection via use of nanosized alumina-coated magnetite solid phase Abs: 
2225538,Diodjo et al. 2013,Silane Coupling Agent for Attaching Fusion-Bonded Epoxy to Steel,,Silane Coupling Agent for Attaching Fusion-Bonded Epoxy to Steel Abs: 
2225537,Gorzin et al. 2013,"Synthesis of a new low-cost activated carbon from activated sludge for the removal of Cr (VI) from aqueous solution: Equilibrium, kinetics, thermodynamics and desorption studies",,"Synthesis of a new low-cost activated carbon from activated sludge for the removal of Cr (VI) from aqueous solution: Equilibrium, kinetics, thermodynamics and desorption studies Abs: "
2225536,Das et al. 2013,"A study on soil physico-chemical, microbial and metal content in Sukinda chromite mine of Odisha, India",,"A study on soil physico-chemical, microbial and metal content in Sukinda chromite mine of Odisha, India Abs: "
2225535,Shcherbakova et al. 2013,Features of transition metal complexation with hydrogels,,Features of transition metal complexation with hydrogels Abs: 
2225534,Goraieb and  Collins 2013,Evaluation of a Doubly Zirconized Silica-Based Stationary Phase for HPLC,,Evaluation of a Doubly Zirconized Silica-Based Stationary Phase for HPLC Abs: 
2225533,Foeldi et al. 2013,Characterization of chromium-containing wastes and soils affected by the production of chromium tanning agents,,Characterization of chromium-containing wastes and soils affected by the production of chromium tanning agents Abs: 
2225531,Kumar and  Chithra 2013,Removal of Cr (VI) from spiked soils by electrokinetics,,Removal of Cr (VI) from spiked soils by electrokinetics Abs: 
2225530,Gao et al. 2013,A GREEN METHOD FOR THE DETERMINATION OF CHROMIUM(VI) AND IRON(III) IN WATER BY SEQUENTIAL INJECTION ANALYSIS AND SPECTROPHOTOMETRIC DETECTION,,A GREEN METHOD FOR THE DETERMINATION OF CHROMIUM(VI) AND IRON(III) IN WATER BY SEQUENTIAL INJECTION ANALYSIS AND SPECTROPHOTOMETRIC DETECTION Abs: 
2225529,Tanaka et al. 2013,Simultaneous and Stoichiometric Water Oxidation and Cr(VI) Reduction in Aqueous Suspensions of Functionalized Plasmonic Photocatalyst Au/TiO2-Pt under Irradiation of Green Light,,Simultaneous and Stoichiometric Water Oxidation and Cr(VI) Reduction in Aqueous Suspensions of Functionalized Plasmonic Photocatalyst Au/TiO2-Pt under Irradiation of Green Light Abs: 
2225528,Rawat et al. 2013,Toxic Metals Biosorption by Jatropha curcas Deoiled Cake: Equilibrium and Kinetic Studies,"The equilibrium sorption of Cr(VI) and Cu(II) from aqueous solution using Jatropha curcas deoiled cake, has been studied with respect to adsorbent dosage, contact time, pH, and initial metal concentration in batch mode experiments. Removal of Cu(II) by deoiled cake was greater than that of Cr(VI). The adsorbent chemical characteristics, studied by Fourier transform-infrared analysis, suggested that the presence of Cr(VI) and Cu(II) in the biomass influenced the bands corresponding to hydroxyl and carboxyl groups. Desorption studies revealed that maximum metals recovery was achieved by HNO3 followed by CH3COOH and HCl. The Freundlich isotherm model showed good fit to the equilibrium adsorption data. The adsorption kinetics followed the pseudo-second-order model, which provided the best correlation for the biosorption process, and suggested that J. curcas deoiled cake can be used as an efficient biosorbent over other commonly used sorbents for decontamination of Cr(VI)- and Cu(II)-containing wastewater.","Toxic Metals Biosorption by Jatropha curcas Deoiled Cake: Equilibrium and Kinetic Studies Abs: The equilibrium sorption of Cr(VI) and Cu(II) from aqueous solution using Jatropha curcas deoiled cake, has been studied with respect to adsorbent dosage, contact time, pH, and initial metal concentration in batch mode experiments. Removal of Cu(II) by deoiled cake was greater than that of Cr(VI). The adsorbent chemical characteristics, studied by Fourier transform-infrared analysis, suggested that the presence of Cr(VI) and Cu(II) in the biomass influenced the bands corresponding to hydroxyl and carboxyl groups. Desorption studies revealed that maximum metals recovery was achieved by HNO3 followed by CH3COOH and HCl. The Freundlich isotherm model showed good fit to the equilibrium adsorption data. The adsorption kinetics followed the pseudo-second-order model, which provided the best correlation for the biosorption process, and suggested that J. curcas deoiled cake can be used as an efficient biosorbent over other commonly used sorbents for decontamination of Cr(VI)- and Cu(II)-containing wastewater."
2225527,Li-ying et al. 2013,Indirect Determination of Cr(III) and Cr(VI) in Milks by Hydride Generation-Fluorescence Spectrometry,,Indirect Determination of Cr(III) and Cr(VI) in Milks by Hydride Generation-Fluorescence Spectrometry Abs: 
2225526,Pereira et al. 2013,"Protective effects of phenolic constituents from Cytisus multiflorus, Lamium album L. and Thymus citriodorus on liver cells",,"Protective effects of phenolic constituents from Cytisus multiflorus, Lamium album L. and Thymus citriodorus on liver cells Abs: "
2225525,Pacurariu et al. 2013,Removal of Cr3+ from Waste Solution by a Bulk Liquid Membrane and Ion- Exchange Membrane Nafion 117,,Removal of Cr3+ from Waste Solution by a Bulk Liquid Membrane and Ion- Exchange Membrane Nafion 117 Abs: 
2225524,Stepniowski et al. 2013,Incorporation of copper chelate ions into anodic alumina walls,,Incorporation of copper chelate ions into anodic alumina walls Abs: 
2225523,Safari et al. 2013,Speciation of chromium in environmental samples by dual electromembrane extraction system followed by high performance liquid chromatography,,Speciation of chromium in environmental samples by dual electromembrane extraction system followed by high performance liquid chromatography Abs: 
2225522,Muslu and  Ergun 2013,"EFFECTS OF COPPER AND CHROMIUM AND HIGH TEMPERATURE ON GROWTH, PROLINE AND PROTEIN CONTENT IN WHEAT SEEDLINGS",,"EFFECTS OF COPPER AND CHROMIUM AND HIGH TEMPERATURE ON GROWTH, PROLINE AND PROTEIN CONTENT IN WHEAT SEEDLINGS Abs: "
2225521,Gurler et al. 2013,Removal of Cr(III) from aqueous solutions using P-EAn and P-MAn/PVDF composite membranes,,Removal of Cr(III) from aqueous solutions using P-EAn and P-MAn/PVDF composite membranes Abs: 
2225520,Santos et al. 2013,Cr(III) biosorption by forest wastes from Araucaria angustifolia and Pinus elliottii: biosorbent surface characterization and chromium quantification by spectrofluorimetry in micellar medium,,Cr(III) biosorption by forest wastes from Araucaria angustifolia and Pinus elliottii: biosorbent surface characterization and chromium quantification by spectrofluorimetry in micellar medium Abs: 
2225519,Kumar et al. 2013,Studies on biosorption of cadmium on grape pomace using response surface methodology,,Studies on biosorption of cadmium on grape pomace using response surface methodology Abs: 
2225518,Mitra et al. 2013,Utilization of solar energy for photoreduction of industrial wastewater containing hexavalent chromium with zinc oxide semiconductor catalyst,,Utilization of solar energy for photoreduction of industrial wastewater containing hexavalent chromium with zinc oxide semiconductor catalyst Abs: 
2225517,Ma et al. 2013,Treatment mechanism of chromium-containing wastewater with carbonate minerals,,Treatment mechanism of chromium-containing wastewater with carbonate minerals Abs: 
2225516,Kiersikowska et al. 2013,Kinetic studies on H+-catalyzed aquation and hydrogen peroxide oxidation of tris-asparaginatochromium(III),,Kinetic studies on H+-catalyzed aquation and hydrogen peroxide oxidation of tris-asparaginatochromium(III) Abs: 
2225515,Miloserdov et al. 2013,High-Temperature Synthesis of Cast Cr2AlC at an Inert Gas Overpressure,,High-Temperature Synthesis of Cast Cr2AlC at an Inert Gas Overpressure Abs: 
2225514,Hadi et al. 2013,"Toxic Heavy Metal Capture Using a Novel Electronic Waste-Based Material-Mechanism, Modeling and Comparison",,"Toxic Heavy Metal Capture Using a Novel Electronic Waste-Based Material-Mechanism, Modeling and Comparison Abs: "
2225513,Noubactep 2013,Metallic iron for environmental remediation: the long walk to evidence,,Metallic iron for environmental remediation: the long walk to evidence Abs: 
2225512,Sarenqiqige et al. 2013,Speciation Analysis of Ultratrace Chromium in Water by On-line Reaction/Concentration/Separation Method Using a Cation-Exchange Column,,Speciation Analysis of Ultratrace Chromium in Water by On-line Reaction/Concentration/Separation Method Using a Cation-Exchange Column Abs: 
2225511,Iskenderian-Epps et al. 2013,Visual Isotope Effects: Demonstrating the Primary Kinetic Isotope Effect in the Chromium(VI) Oxidation of 2-Propanol-d(8) and Methanol-d(4),,Visual Isotope Effects: Demonstrating the Primary Kinetic Isotope Effect in the Chromium(VI) Oxidation of 2-Propanol-d(8) and Methanol-d(4) Abs: 
2225510,Wise et al. 2013,Hexavalent chromium impairs DNA repair resulting in mitotic disruption and chromosome instability,"Hexavalent chromium (Cr(VI)) is a human lung carcinogen of global concern. One leading hypothesis for the carcinogenicity of Cr(VI) posits that it causes a DNA double-strand break (DSB) repair deficiency which leads to mitotic disruption, chromosome instability, and neoplastic transformation. To determine if these phenotypes could be induced and remain as permanent phenotypic changes, we exposed human lung cells to lead chromate for three sequential 24 h periods, each separated by a month. After treatment, cells were seeded at colony forming density, cloned, expanded, and retreated. Each generation of clones was tested for chromosome instability, DNA repair capacity, and soft agar growth. After the first treatment, lead chromate-treated cells exhibited a normal chromosome complement, though a few clones showed a repair deficient phenotype. After the second exposure, more than half of the clones acquired an abnormal karyotype including numerical and structural alterations and many showed deficient DNA DSB repair. The third treatment resulted in more abnormal clones, previously abnormal clones acquiring additional abnormalities, and most clones were repair deficient. Further investigation revealed that some clones exhibited centrosome amplification, abnormal mitotic figures, and aberrant Mad1 kinetochore localization, indicating that they have underlying permanent phenotypic defects in mitotic regulation. Additionally, several were unable to form radiation-induced Rad51 foci, suggesting a defect in the homologous recombination repair pathway. Clones from the third generation were able to form colonies in soft agar suggesting neoplastic transformation. This work was supported by NIEHS grant ES016893 (J.P.W.) and the Maine Center for Toxicology and Environmental Health.","Hexavalent chromium impairs DNA repair resulting in mitotic disruption and chromosome instability Abs: Hexavalent chromium (Cr(VI)) is a human lung carcinogen of global concern. One leading hypothesis for the carcinogenicity of Cr(VI) posits that it causes a DNA double-strand break (DSB) repair deficiency which leads to mitotic disruption, chromosome instability, and neoplastic transformation. To determine if these phenotypes could be induced and remain as permanent phenotypic changes, we exposed human lung cells to lead chromate for three sequential 24 h periods, each separated by a month. After treatment, cells were seeded at colony forming density, cloned, expanded, and retreated. Each generation of clones was tested for chromosome instability, DNA repair capacity, and soft agar growth. After the first treatment, lead chromate-treated cells exhibited a normal chromosome complement, though a few clones showed a repair deficient phenotype. After the second exposure, more than half of the clones acquired an abnormal karyotype including numerical and structural alterations and many showed deficient DNA DSB repair. The third treatment resulted in more abnormal clones, previously abnormal clones acquiring additional abnormalities, and most clones were repair deficient. Further investigation revealed that some clones exhibited centrosome amplification, abnormal mitotic figures, and aberrant Mad1 kinetochore localization, indicating that they have underlying permanent phenotypic defects in mitotic regulation. Additionally, several were unable to form radiation-induced Rad51 foci, suggesting a defect in the homologous recombination repair pathway. Clones from the third generation were able to form colonies in soft agar suggesting neoplastic transformation. This work was supported by NIEHS grant ES016893 (J.P.W.) and the Maine Center for Toxicology and Environmental Health."
2225509,Oladoja and  Ahmad 2013,Gastropod shell as a precursor for the synthesis of binary alkali-earth and transition metal oxide for Cr(VI) Abstraction from Aqua System,,Gastropod shell as a precursor for the synthesis of binary alkali-earth and transition metal oxide for Cr(VI) Abstraction from Aqua System Abs: 
2225508,Gurung et al. 2013,Use of sulfur-oxidizing bacteria for assessment of chromium-contaminated soil,,Use of sulfur-oxidizing bacteria for assessment of chromium-contaminated soil Abs: 
2225507,Etchie et al. 2013,Prioritizing hazardous pollutants in two Nigerian water supply schemes: a risk-based approach,,Prioritizing hazardous pollutants in two Nigerian water supply schemes: a risk-based approach Abs: 
2225506,Frunza et al. 2013,Effects on body and sexual organs weight in male rats after potassium dichromate exposure in prepubertal period,,Effects on body and sexual organs weight in male rats after potassium dichromate exposure in prepubertal period Abs: 
2225505,Chen et al. 2013,Preparation of flake-like polyaniline/montmorillonite nanocomposites and their application for removal of Cr(VI) ions in aqueous solution,,Preparation of flake-like polyaniline/montmorillonite nanocomposites and their application for removal of Cr(VI) ions in aqueous solution Abs: 
2225504,Golbaz et al. 2013,"The study of Fenton oxidation process efficiency in the simultaneous removal of phenol, cyanide, and chromium (VI) from synthetic wastewater",,"The study of Fenton oxidation process efficiency in the simultaneous removal of phenol, cyanide, and chromium (VI) from synthetic wastewater Abs: "
2225503,Cuesta Zapata et al. 2013,Effect of hydrothermal treatment on Cr-SiO2 mesoporous materials,,Effect of hydrothermal treatment on Cr-SiO2 mesoporous materials Abs: 
2225502,Winsco et al. 2013,Influence of maternal plane of nutrition on mares and their foals: Determination of mare performance and voluntary dry matter intake during late pregnancy using a dual-marker system,"Thirty pregnant mares (538 to 695 kg BW; 4 to 19 yr of age) were used to evaluate the effects of plane of nutrition on DMI of hay and mare performance (BW, BCS, and rump fat) during the last third of pregnancy. Mares were divided into 4 blocks by their expected foaling date and randomly assigned within block to either a hay or concentrate plus hay diet (concentrate fed at 0.75% BW, as-fed basis) with 15 mares per treatment. Treatments began 110 d before expected foaling date (230 d of gestation) and terminated at parturition. Mares were housed by block and allowed ad libitum access to coastal Bermuda grass (C. dactylon) hay, and concentrate-supplemented mares were fed twice daily in individual stalls. Performance variables were recorded every 14 d, with the last measurements obtained before foaling being considered a prepartum measurement. To evaluate DMI of hay, a dual-marker system was used at 9, 10, and 11 mo of gestation. Titanium dioxide was dosed at 10 g for 14 d. Fecal grab samples were obtained on the last 4 d twice daily via rectal palpation at 12-h intervals with times advancing 3 h each day to account for diurnal variation and to ultimately represent a 24-h period. Fecal samples were analyzed for TiO2 using a colorimetric procedure. Fecal, concentrate, and hay samples were also analyzed for acid detergent insoluble ash. Treatment tended to influence prepartum BW (P = 0.09) and affected prepartum BCS (P &lt; 0.01) and rump fat (P = 0.01), with hay-fed mares having decreased BW and BCS from d 0 (beginning of feeding trial or d 230 of gestation) until parturition, whereas mares fed concentrate gained BW and BCS (P &lt; 0.01). Mares fed only hay consumed 2.3% BW of forage compared with 1.8% BW for concentrate-fed mares (P &lt; 0.01). Regardless of treatment, month of gestation influenced forage intake (P &lt; 0.06), with mares consuming less during the 10th month of gestation and more in the 11th month (1.9% and 2.2% BW, respectively). These data indicate that the altered plane of nutrition of mares in late gestation influenced mare performance. Furthermore, DMI of hay was influenced by both diet and month of gestation. Continued research investigating manipulation of maternal nutrition and its effects on DMI would be beneficial to completely understand the relationships of these observations.","Influence of maternal plane of nutrition on mares and their foals: Determination of mare performance and voluntary dry matter intake during late pregnancy using a dual-marker system Abs: Thirty pregnant mares (538 to 695 kg BW; 4 to 19 yr of age) were used to evaluate the effects of plane of nutrition on DMI of hay and mare performance (BW, BCS, and rump fat) during the last third of pregnancy. Mares were divided into 4 blocks by their expected foaling date and randomly assigned within block to either a hay or concentrate plus hay diet (concentrate fed at 0.75% BW, as-fed basis) with 15 mares per treatment. Treatments began 110 d before expected foaling date (230 d of gestation) and terminated at parturition. Mares were housed by block and allowed ad libitum access to coastal Bermuda grass (C. dactylon) hay, and concentrate-supplemented mares were fed twice daily in individual stalls. Performance variables were recorded every 14 d, with the last measurements obtained before foaling being considered a prepartum measurement. To evaluate DMI of hay, a dual-marker system was used at 9, 10, and 11 mo of gestation. Titanium dioxide was dosed at 10 g for 14 d. Fecal grab samples were obtained on the last 4 d twice daily via rectal palpation at 12-h intervals with times advancing 3 h each day to account for diurnal variation and to ultimately represent a 24-h period. Fecal samples were analyzed for TiO2 using a colorimetric procedure. Fecal, concentrate, and hay samples were also analyzed for acid detergent insoluble ash. Treatment tended to influence prepartum BW (P = 0.09) and affected prepartum BCS (P &lt; 0.01) and rump fat (P = 0.01), with hay-fed mares having decreased BW and BCS from d 0 (beginning of feeding trial or d 230 of gestation) until parturition, whereas mares fed concentrate gained BW and BCS (P &lt; 0.01). Mares fed only hay consumed 2.3% BW of forage compared with 1.8% BW for concentrate-fed mares (P &lt; 0.01). Regardless of treatment, month of gestation influenced forage intake (P &lt; 0.06), with mares consuming less during the 10th month of gestation and more in the 11th month (1.9% and 2.2% BW, respectively). These data indicate that the altered plane of nutrition of mares in late gestation influenced mare performance. Furthermore, DMI of hay was influenced by both diet and month of gestation. Continued research investigating manipulation of maternal nutrition and its effects on DMI would be beneficial to completely understand the relationships of these observations."
2225501,Zhou et al. 2013,A solvothermal method to produce RGO-Fe3O4 hybrid composite for fast chromium removal from aqueous solution,,A solvothermal method to produce RGO-Fe3O4 hybrid composite for fast chromium removal from aqueous solution Abs: 
2225500,Yan et al. 2013,Carbon nanotubes promote Cr(VI) reduction by alginate-immobilized Shewanella oneidensis MR-1,,Carbon nanotubes promote Cr(VI) reduction by alginate-immobilized Shewanella oneidensis MR-1 Abs: 
2225499,Okeniyi et al. 2013,Electrochemical Performance of Sodium Dichromate Partial Replacement Models by Triethanolamine Admixtures on Steel-Rebar Corrosion in Concretes,,Electrochemical Performance of Sodium Dichromate Partial Replacement Models by Triethanolamine Admixtures on Steel-Rebar Corrosion in Concretes Abs: 
2225498,Ren et al. 2013,Effectiveness of Thermal and Acid Modification on Hexavalent Chromium Removal by Electrolyte Water Treatment Residuals,,Effectiveness of Thermal and Acid Modification on Hexavalent Chromium Removal by Electrolyte Water Treatment Residuals Abs: 
2225497,Chen et al. 2013,Surface Modification of Hydrophobic Resin with Tricaprylmethylammonium Chloride for the Removal of Trace Hexavalent Chromium,,Surface Modification of Hydrophobic Resin with Tricaprylmethylammonium Chloride for the Removal of Trace Hexavalent Chromium Abs: 
2225496,Dhiwar et al. 2013,Nano-iron oxide-encapsulated chitosan microspheres as novel adsorbent for removal of Ni (II) ions from aqueous solution,,Nano-iron oxide-encapsulated chitosan microspheres as novel adsorbent for removal of Ni (II) ions from aqueous solution Abs: 
2225495,Nekram and  Urmila 2013,Removal of Chromium (VI) Ions from Wastewaters by Low Cost Adsorbent,,Removal of Chromium (VI) Ions from Wastewaters by Low Cost Adsorbent Abs: 
2225494,Xingyu et al. 2013,"Aging, Washing and Drying Processes of UO2 Gelled Spheres","The aging, washing and drying processes are in sequence accomplished in one device which is suitable for the batched preparation of UO2 gelled spheres (similar to 3 kgU/batch), and also can be used in large-scale production. The inside and outside gelation of gelled spheres are complete and uniform through pre-aging process and heating rate controlling. Temperature of deionized water and frequency of lavation are controlled in washing to avoid cracking and decrease liquid waste. The vacuum degree and temperature in drying process have been adjusted to avoid cracking and make drying uniformly. The NO3- content variation with time in aging solution and the content in washing solution have been measured by potassium dichromate titrimetric analysis, and then the processes whether finished to be determined. Batches of verification test are smooth-going using the AWD process, and the UO2 kernels satisfied design requirements have been prepared finally.","Aging, Washing and Drying Processes of UO2 Gelled Spheres Abs: The aging, washing and drying processes are in sequence accomplished in one device which is suitable for the batched preparation of UO2 gelled spheres (similar to 3 kgU/batch), and also can be used in large-scale production. The inside and outside gelation of gelled spheres are complete and uniform through pre-aging process and heating rate controlling. Temperature of deionized water and frequency of lavation are controlled in washing to avoid cracking and decrease liquid waste. The vacuum degree and temperature in drying process have been adjusted to avoid cracking and make drying uniformly. The NO3- content variation with time in aging solution and the content in washing solution have been measured by potassium dichromate titrimetric analysis, and then the processes whether finished to be determined. Batches of verification test are smooth-going using the AWD process, and the UO2 kernels satisfied design requirements have been prepared finally."
2225493,Dhal et al. 2013,Process optimization for bio-beneficiation of a chromite concentrate by a Cr(VI) reducing native microbe (Bacillus sp.),,Process optimization for bio-beneficiation of a chromite concentrate by a Cr(VI) reducing native microbe (Bacillus sp.) Abs: 
2225492,Chathuranga et al. 2013,Biosorption of Cr(III) and Cr(VI) species from aqueous solution by Cabomba caroliniana: kinetic and equilibrium study,,Biosorption of Cr(III) and Cr(VI) species from aqueous solution by Cabomba caroliniana: kinetic and equilibrium study Abs: 
2225491,Xie et al. 2013,Adsorption of organic pollutants by surfactant modified zeolite as controlled by surfactant chain length,,Adsorption of organic pollutants by surfactant modified zeolite as controlled by surfactant chain length Abs: 
2225490,Long et al. 2013,Cr(VI) Resistance and Removal by Indigenous Bacteria Isolated from Chromium-Contaminated Soil,,Cr(VI) Resistance and Removal by Indigenous Bacteria Isolated from Chromium-Contaminated Soil Abs: 
2225489,Zuliani et al. 2013,The use of stable isotopes for Cr(VI) determination in silty-clay soil solution,,The use of stable isotopes for Cr(VI) determination in silty-clay soil solution Abs: 
2225488,Wu et al. 2013,Competitive Adsorption of Cr (VI) and Ni (II) onto Coconut Shell Activated Carbon in Single and Binary Systems,,Competitive Adsorption of Cr (VI) and Ni (II) onto Coconut Shell Activated Carbon in Single and Binary Systems Abs: 
2225487,Olguin et al. 2013,Hexavalent Chromium Removal From Aqueous Solutions by Fe-Modified Peanut Husk,,Hexavalent Chromium Removal From Aqueous Solutions by Fe-Modified Peanut Husk Abs: 
2225486,Lin et al. 2013,An Improved Procedure for Oxidative Cleavage of Oximes to the Corresponding Carbonyl Compounds With Chromic Acid Supported on Kieselguhr Under Viscous Conditions,,An Improved Procedure for Oxidative Cleavage of Oximes to the Corresponding Carbonyl Compounds With Chromic Acid Supported on Kieselguhr Under Viscous Conditions Abs: 
2225485,Puszkarewicz et al. 2013,Efficiency of the chromium(VI) removal from aqueous solutions by ion exchange process,,Efficiency of the chromium(VI) removal from aqueous solutions by ion exchange process Abs: 
2225484,Naeher et al. 2013,Maleimides in recent sediments - Using chlorophyll degradation products for palaeoenvironmental reconstructions,,Maleimides in recent sediments - Using chlorophyll degradation products for palaeoenvironmental reconstructions Abs: 
2225483,Wanner et al. 2013,Unraveling the partial failure of a permeable reactive barrier using a multi-tracer experiment and Cr isotope measurements,,Unraveling the partial failure of a permeable reactive barrier using a multi-tracer experiment and Cr isotope measurements Abs: 
2225482,Ozcan et al. 2013,Synthesis of a novel calix[4]azacrown ionophore and its extraction ability toward Cr(VI),,Synthesis of a novel calix[4]azacrown ionophore and its extraction ability toward Cr(VI) Abs: 
2225481,Pokhmurskii et al. 2013,Aluminium alloy corrosion inhibition by chromate-free composition of zinc phosphate and ion-exchanged zeolite,,Aluminium alloy corrosion inhibition by chromate-free composition of zinc phosphate and ion-exchanged zeolite Abs: 
2225480,Yu et al. 2013,Magnetic Chitosan-Iron(III) Hydrogel as a Fast and Reusable Adsorbent for Chromium(VI) Removal,,Magnetic Chitosan-Iron(III) Hydrogel as a Fast and Reusable Adsorbent for Chromium(VI) Removal Abs: 
2225479,Li and  Swain 2013,Effects of Aging Temperature and Time on the Corrosion Protection Provided by Trivalent Chromium Process Coatings on AA2024-T3,,Effects of Aging Temperature and Time on the Corrosion Protection Provided by Trivalent Chromium Process Coatings on AA2024-T3 Abs: 
2225478,Meredith et al. 2013,Direct evidence from hydropyrolysis for the retention of long alkyl moieties in black carbon fractions isolated by acidified dichromate oxidation,,Direct evidence from hydropyrolysis for the retention of long alkyl moieties in black carbon fractions isolated by acidified dichromate oxidation Abs: 
2225477,Suk et al. 2013,Thermally Crosslinked Polyvinyl Alcohol (PVA) Layers for the Passivation of Pentacene Thin-Film Transistors,,Thermally Crosslinked Polyvinyl Alcohol (PVA) Layers for the Passivation of Pentacene Thin-Film Transistors Abs: 
2225476,Pandikumar and  Ramaraj 2013,Photocatalytic reduction of hexavalent chromium at gold nanoparticles modified titania nanotubes,,Photocatalytic reduction of hexavalent chromium at gold nanoparticles modified titania nanotubes Abs: 
2225475,Zhang et al. 2013,"Zirconium cross-linked chitosan composite: Preparation, characterization and application in adsorption of Cr(VI)",,"Zirconium cross-linked chitosan composite: Preparation, characterization and application in adsorption of Cr(VI) Abs: "
2225474,Epifani et al. 2013,Suppression of the NO2 interference by chromium addition in WO3-based ammonia sensors. Investigation of the structural properties and of the related sensing pathways,,Suppression of the NO2 interference by chromium addition in WO3-based ammonia sensors. Investigation of the structural properties and of the related sensing pathways Abs: 
2225473,Pradas-Del-Real et al. 2013,"Effect of genotype, Cr(III) and Cr(VI) on plant growth and micronutrient status in Silene vulgaris (Moench)",,"Effect of genotype, Cr(III) and Cr(VI) on plant growth and micronutrient status in Silene vulgaris (Moench) Abs: "
2225472,Zeeb et al. 2013,Preconcentration and Trace Determination of Chromium Using Modified Ionic Liquid Cold-Induced Aggregation Dispersive Liquid-Liquid Microextraction: Application to Different Water and Food Samples,,Preconcentration and Trace Determination of Chromium Using Modified Ionic Liquid Cold-Induced Aggregation Dispersive Liquid-Liquid Microextraction: Application to Different Water and Food Samples Abs: 
2225471,Kumar et al. 2013,Low-cost synthesis of metal oxide nanoparticles and their application in adsorption of commercial dye and heavy metal ion in aqueous solution,,Low-cost synthesis of metal oxide nanoparticles and their application in adsorption of commercial dye and heavy metal ion in aqueous solution Abs: 
2225470,Xiao et al. 2013,MnFe2O4/chitosan nanocomposites as a recyclable adsorbent for the removal of hexavalent chromium,,MnFe2O4/chitosan nanocomposites as a recyclable adsorbent for the removal of hexavalent chromium Abs: 
2225469,Zhang et al. 2013,HNO3-involved one-step low temperature solvothermal synthesis of N-doped TiO2 nanocrystals for efficient photocatalytic reduction of Cr(VI) in water,"A one-step low temperature (180 degrees C) solvothermal route, which utilized HNO3 as the nitrogen source, was proposed for the synthesis of nanocrystalline N-doped TiO2 (denoted as TiO2-HNO3). The structure, composition, BET specific surface area and optical properties of TiO2-HNO3 were characterized by X-ray diffraction, Fourier transform infrared spectroscopy, X-ray photoelectron spectroscopy, transmission electron microscopy, high resolution transmission electron microscopy, N-2 adsorption-desorption isotherms and UV-vis diffuse reflectance spectroscopy. The photocatalytic properties of TiO2-HNO3 were tested for the reduction of Cr(VI) in water under both UV and visible light (lambda > 420 nm) irradiation, and compared with those of TiO2-NH3 center dot H2O (which was solvothermally synthesized using NH3 center dot H2O as the nitrogen source) and TiO2 P25. The photocatalytic results demonstrated that TiO2-HNO3 possessed much higher photocatalytic activity than TiO2-NH3 center dot H2O and TiO2 P25 in the reduction of aqueous Cr(VI) under both UV and visible light (lambda > 420 nm) irradiation, and the dosage of TiO2-HNO3 and the initial concentration of Cr(VI) aqueous solution had significant effects on the efficiency of Cr(VI) reduction. Besides, Cr(VI) was reduced to Cr(III) after the TiO2-HNO3-mediated photocatalytic reactions. The present work suggests that HNO3 is a promising nitrogen source for low temperature solvothermal synthesis of nanocrystalline N-doped TiO2, which can be applied as a visible light-activated photocatalyst in efficient utilization of solar energy for treating Cr(VI) wastewater. (c) 2013 Elsevier B.V. All rights reserved.","HNO3-involved one-step low temperature solvothermal synthesis of N-doped TiO2 nanocrystals for efficient photocatalytic reduction of Cr(VI) in water Abs: A one-step low temperature (180 degrees C) solvothermal route, which utilized HNO3 as the nitrogen source, was proposed for the synthesis of nanocrystalline N-doped TiO2 (denoted as TiO2-HNO3). The structure, composition, BET specific surface area and optical properties of TiO2-HNO3 were characterized by X-ray diffraction, Fourier transform infrared spectroscopy, X-ray photoelectron spectroscopy, transmission electron microscopy, high resolution transmission electron microscopy, N-2 adsorption-desorption isotherms and UV-vis diffuse reflectance spectroscopy. The photocatalytic properties of TiO2-HNO3 were tested for the reduction of Cr(VI) in water under both UV and visible light (lambda > 420 nm) irradiation, and compared with those of TiO2-NH3 center dot H2O (which was solvothermally synthesized using NH3 center dot H2O as the nitrogen source) and TiO2 P25. The photocatalytic results demonstrated that TiO2-HNO3 possessed much higher photocatalytic activity than TiO2-NH3 center dot H2O and TiO2 P25 in the reduction of aqueous Cr(VI) under both UV and visible light (lambda > 420 nm) irradiation, and the dosage of TiO2-HNO3 and the initial concentration of Cr(VI) aqueous solution had significant effects on the efficiency of Cr(VI) reduction. Besides, Cr(VI) was reduced to Cr(III) after the TiO2-HNO3-mediated photocatalytic reactions. The present work suggests that HNO3 is a promising nitrogen source for low temperature solvothermal synthesis of nanocrystalline N-doped TiO2, which can be applied as a visible light-activated photocatalyst in efficient utilization of solar energy for treating Cr(VI) wastewater. (c) 2013 Elsevier B.V. All rights reserved."
2225468,Wu et al. 2013,Photocatalytic reduction of Cr(VI) with TiO2 film under visible light,"The performance of photocatalytic reduction of chromium (VI) via a new TiO(2) film and a platinum anode was systematically evaluated. The as-prepared TiO(2) film is composed of a dye-sensitized zone and a catalysis zone. Charge separation was accomplished with electron transferring to the catalysis zone and positive charge transforming to an anode. A powerful reduction ability of the reaction system was achieved in the absence of any organics under visible light irradiation. Several parameters including pH, dissolved O(2), the primary active species, the durability of the as-synthetized film and so on were investigated.","Photocatalytic reduction of Cr(VI) with TiO2 film under visible light Abs: The performance of photocatalytic reduction of chromium (VI) via a new TiO(2) film and a platinum anode was systematically evaluated. The as-prepared TiO(2) film is composed of a dye-sensitized zone and a catalysis zone. Charge separation was accomplished with electron transferring to the catalysis zone and positive charge transforming to an anode. A powerful reduction ability of the reaction system was achieved in the absence of any organics under visible light irradiation. Several parameters including pH, dissolved O(2), the primary active species, the durability of the as-synthetized film and so on were investigated."
2225467,Lamb et al. 2013,Mathematical Modelling of Toxicity Associated with Intracellular Chromium Reduction,,Mathematical Modelling of Toxicity Associated with Intracellular Chromium Reduction Abs: 
2225466,Kantar et al. 2014,Effect of exopolymeric substances on the kinetics of sorption and desorption of trivalent chromium in soil,,Effect of exopolymeric substances on the kinetics of sorption and desorption of trivalent chromium in soil Abs: 
2225465,Xu et al. 2013,The Effect of Probe Path Length Calibration on Dissolution Tests Performed with a Fiber-Optic In Situ Dissolution Test System,,The Effect of Probe Path Length Calibration on Dissolution Tests Performed with a Fiber-Optic In Situ Dissolution Test System Abs: 
2225464,Brown et al. 2013,Consequences of exposure to peri-articular injections of micro- and nano-particulate cobalt-Chromium alloy,,Consequences of exposure to peri-articular injections of micro- and nano-particulate cobalt-Chromium alloy Abs: 
2225463,Ghosh et al. 2013,Rate enhancement via micelle encapsulation for room temperature metal catalyzed Ce(IV) oxidation of formaldehyde to formic acid in aqueous medium at atmospheric pressure: A kinetic approach,,Rate enhancement via micelle encapsulation for room temperature metal catalyzed Ce(IV) oxidation of formaldehyde to formic acid in aqueous medium at atmospheric pressure: A kinetic approach Abs: 
2225462,Qian et al. 2013,Alteration of Th1/Th2/Th17 cytokine profile and humoral immune responses associated with chromate exposure,,Alteration of Th1/Th2/Th17 cytokine profile and humoral immune responses associated with chromate exposure Abs: 
2225461,Singh et al. 2014,KOCURIA FLAVA INDUCED GROWTH AND CHROMIUM ACCUMULATION IN CICER ARIETINUM L,,KOCURIA FLAVA INDUCED GROWTH AND CHROMIUM ACCUMULATION IN CICER ARIETINUM L Abs: 
2225460,Zhang et al. 2013,The dispersity-dependent interaction between montmorillonite supported nZVI and Cr(VI) in aqueous solution,,The dispersity-dependent interaction between montmorillonite supported nZVI and Cr(VI) in aqueous solution Abs: 
2225459,Zhong et al. 2013,A novel amphoteric adsorbent derived from biomass materials: Synthesis and adsorption for Cu(II)/Cr(VI) in single and binary systems,,A novel amphoteric adsorbent derived from biomass materials: Synthesis and adsorption for Cu(II)/Cr(VI) in single and binary systems Abs: 
2225458,Kim et al. 2013,Self-rotating photocatalytic system for aqueous Cr(VI) reduction on TiO2 nanotube/Ti mesh substrate,,Self-rotating photocatalytic system for aqueous Cr(VI) reduction on TiO2 nanotube/Ti mesh substrate Abs: 
2225457,Weng et al. 2013,Chitosan stabilized bimetallic Fe/Ni nanoparticles used to remove mixed contaminants-amoxicillin and Cd (II) from aqueous solutions,,Chitosan stabilized bimetallic Fe/Ni nanoparticles used to remove mixed contaminants-amoxicillin and Cd (II) from aqueous solutions Abs: 
2225456,Lodeiro and  Sillanpaa 2013,Gold reduction in batch and column experiments using silica gel derivates and seaweed biomass,,Gold reduction in batch and column experiments using silica gel derivates and seaweed biomass Abs: 
2225455,Kumar et al. 2013,A novel amine impregnated graphene oxide adsorbent for the removal of hexavalent chromium,,A novel amine impregnated graphene oxide adsorbent for the removal of hexavalent chromium Abs: 
2225454,Mahmoud et al. 2013,Removal and speciation of chromium by static step-by-step deposition and extraction technique,,Removal and speciation of chromium by static step-by-step deposition and extraction technique Abs: 
2225453,Murugavelh and  Mohanty 2013,"Isolation, identification and characterization of Cr(VI) reducing Bacillus cereus from chromium contaminated soil",,"Isolation, identification and characterization of Cr(VI) reducing Bacillus cereus from chromium contaminated soil Abs: "
2225452,Xiaoming et al. 2013,PREPARATION AND CHARACTERIZATION OF ANTI-CORROSION SELF-HEALING AND HYDROPHOBIC COATING ON ALUMINUM ALLOY,"Aluminum alloy has been widely used as the basic material in many industries because of its low density and high strength to weight ratio. Poor resistance to corrosion, however, limits the variety of practical applications of aluminum alloy. Traditionally, this problem was faced with the use of chromate conversion coatings which result in effective corrosion protection because of the self-healing property. However, the presence of toxic hexavalent chromium compounds makes those coatings very hazardous to the environment. Consequently, it is necessary to develop new environmentally compliant, chromate (VI)-free alternatives. Recently, sol-gel technology provides a new promising approach to prepare protective coatings on aluminum alloy. It has many advantages, such as the simple operation and environmental protection, etc. In this work, an Ormosil coating was developed on aluminum alloy through the sol-gel method using triethoxyoctylsilane (TEOCS) and tetraethylorthosilicate (TEOS) as the precursors. The sol-gel coatings were deposited by dip-coating method on aluminum alloy substrate. The sol gel coatings doped with different concentrations of cerium salt (Ce(NO3)(3)center dot 6H(2)O) were investigated. Surface morphology, wettability, anti-corrosion and self-healing of the sol-gel coatings non-doped and doped cerium salt were characterized by using atomic force microscopy, contact angle measurements, electrochemical impedance spectroscopy and scanning electrochemical microscopy. The hydrophobic of the coatings was evaluated by means of contact angle measurements. The corrosion resistance of the coatings was investigated by means of electrochemical impedance spectroscopy measurements, and the anti-corrosion, self-healing properties were discussed based on equivalent circuit fitting. The corrosion behavior of the damaged sol-gel coatings was studied by scanning electrochemical microscopy. The results indicated that it had a marked effect on the surface morphology, corrosion resistance and hydrophobicity when cerium salt was added to the Ormosil sol-gel coating. The contact angle of the Ormosil sol gel coating is about 92.0 degrees. Cerium salt doped coatings have a better hydrophobicity due to marked improvement of the surface morphology. This positive effect was more evident when the concentration of the doped cerium salt is 0.005 mol/L in the silane solution. It was found that cerium salt doped coatings were less resistant to corrosion than non-doped coating at initial immersion. However, the coating doped with 0.005 mol/L cerium salt rendered improved protection after longer time immersion because of the inhibitive action of Ce3+. It can be released at the defects, hindering the further corrosion reactions at defective sites and showing the self-healing ability of the doped with cerium salt Ormosil sol-gel coating.","PREPARATION AND CHARACTERIZATION OF ANTI-CORROSION SELF-HEALING AND HYDROPHOBIC COATING ON ALUMINUM ALLOY Abs: Aluminum alloy has been widely used as the basic material in many industries because of its low density and high strength to weight ratio. Poor resistance to corrosion, however, limits the variety of practical applications of aluminum alloy. Traditionally, this problem was faced with the use of chromate conversion coatings which result in effective corrosion protection because of the self-healing property. However, the presence of toxic hexavalent chromium compounds makes those coatings very hazardous to the environment. Consequently, it is necessary to develop new environmentally compliant, chromate (VI)-free alternatives. Recently, sol-gel technology provides a new promising approach to prepare protective coatings on aluminum alloy. It has many advantages, such as the simple operation and environmental protection, etc. In this work, an Ormosil coating was developed on aluminum alloy through the sol-gel method using triethoxyoctylsilane (TEOCS) and tetraethylorthosilicate (TEOS) as the precursors. The sol-gel coatings were deposited by dip-coating method on aluminum alloy substrate. The sol gel coatings doped with different concentrations of cerium salt (Ce(NO3)(3)center dot 6H(2)O) were investigated. Surface morphology, wettability, anti-corrosion and self-healing of the sol-gel coatings non-doped and doped cerium salt were characterized by using atomic force microscopy, contact angle measurements, electrochemical impedance spectroscopy and scanning electrochemical microscopy. The hydrophobic of the coatings was evaluated by means of contact angle measurements. The corrosion resistance of the coatings was investigated by means of electrochemical impedance spectroscopy measurements, and the anti-corrosion, self-healing properties were discussed based on equivalent circuit fitting. The corrosion behavior of the damaged sol-gel coatings was studied by scanning electrochemical microscopy. The results indicated that it had a marked effect on the surface morphology, corrosion resistance and hydrophobicity when cerium salt was added to the Ormosil sol-gel coating. The contact angle of the Ormosil sol gel coating is about 92.0 degrees. Cerium salt doped coatings have a better hydrophobicity due to marked improvement of the surface morphology. This positive effect was more evident when the concentration of the doped cerium salt is 0.005 mol/L in the silane solution. It was found that cerium salt doped coatings were less resistant to corrosion than non-doped coating at initial immersion. However, the coating doped with 0.005 mol/L cerium salt rendered improved protection after longer time immersion because of the inhibitive action of Ce3+. It can be released at the defects, hindering the further corrosion reactions at defective sites and showing the self-healing ability of the doped with cerium salt Ormosil sol-gel coating."
2225451,Chen et al. 2013,Reduction of Cr (VI) by organic acids in the presence of Al (III),,Reduction of Cr (VI) by organic acids in the presence of Al (III) Abs: 
2225450,Davarkhah et al. 2013,Kinetic studies on the extraction of uranium(VI) from phosphoric acid medium by bulk liquid membrane containing di-2-ethylhexyl phosphoric acid,,Kinetic studies on the extraction of uranium(VI) from phosphoric acid medium by bulk liquid membrane containing di-2-ethylhexyl phosphoric acid Abs: 
2225449,Gucic et al. 2013,"Apparent carbohydrate and lipid digestibility of feeds for whiteleg shrimp, Litopenaeus vannamei (Decapoda: Penaeidae), cultivated at different salinities",,"Apparent carbohydrate and lipid digestibility of feeds for whiteleg shrimp, Litopenaeus vannamei (Decapoda: Penaeidae), cultivated at different salinities Abs: "
2225448,Duliu et al. 2013,Synthesis of Iron Phosphate Coated Nano-Fe3O4 Particles and Its Application in the Enrichment of Chromium(III) from Aqueous Solutions,,Synthesis of Iron Phosphate Coated Nano-Fe3O4 Particles and Its Application in the Enrichment of Chromium(III) from Aqueous Solutions Abs: 
2225447,Salamanca et al. 2013,Chromate Reduction in Anaerobic Systems by Bacterial Strain Pseudomonas aeruginosa CRM100,,Chromate Reduction in Anaerobic Systems by Bacterial Strain Pseudomonas aeruginosa CRM100 Abs: 
2225446,Doke et al. 2013,Diffusion Mechanisms of Biosorption of Cr(VI) onto Powdered Cotton Stalk,,Diffusion Mechanisms of Biosorption of Cr(VI) onto Powdered Cotton Stalk Abs: 
2225445,Ng et al. 2013,Synergistic effect of Trichoderma reesei cellulases on agricultural tea waste for adsorption of heavy metal Cr(VI),,Synergistic effect of Trichoderma reesei cellulases on agricultural tea waste for adsorption of heavy metal Cr(VI) Abs: 
2225444,Pesciaroli et al. 2013,Pleurotus ostreatus biofilms exhibit higher tolerance to toxicants than free-floating counterparts,,Pleurotus ostreatus biofilms exhibit higher tolerance to toxicants than free-floating counterparts Abs: 
2225443,Crowe et al. 2013,Atmospheric oxygenation three billion years ago,,Atmospheric oxygenation three billion years ago Abs: 
2225442,Ferreira et al. 2013,Assessment of Arthrobacter viscosus as reactive medium for forming permeable reactive biobarrier applied to PAHs remediation,,Assessment of Arthrobacter viscosus as reactive medium for forming permeable reactive biobarrier applied to PAHs remediation Abs: 
2225441,Tayade and  Adivarekar 2013,Dyeing of cotton fabric with Cuminum cyminum L. as a natural dye and its comparison with synthetic dye,,Dyeing of cotton fabric with Cuminum cyminum L. as a natural dye and its comparison with synthetic dye Abs: 
2225440,Neeraj 2013,Immobilization of Hazardous Cr(VI) in blended cement: XRD and Leaching Studies,,Immobilization of Hazardous Cr(VI) in blended cement: XRD and Leaching Studies Abs: 
2225439,Mike et al. 2013,"Regulation of cytotoxic, non-estrogenic, oxidative stress-induced processes of zearalenone in the fission yeast Schizosaccharomyces pombe",,"Regulation of cytotoxic, non-estrogenic, oxidative stress-induced processes of zearalenone in the fission yeast Schizosaccharomyces pombe Abs: "
2225438,Pujol et al. 2013,"Modelling synergistic sorption of Cr(VI), Cu(II) and Ni(II) onto exhausted coffee wastes from binary mixtures Cr(VI)-Cu(II) and Cr(VI)-Ni(II)",,"Modelling synergistic sorption of Cr(VI), Cu(II) and Ni(II) onto exhausted coffee wastes from binary mixtures Cr(VI)-Cu(II) and Cr(VI)-Ni(II) Abs: "
2225437,Zaharia et al. 2013,Facilitated transport of 5-aminosalicylic acid through bulk liquid membrane,,Facilitated transport of 5-aminosalicylic acid through bulk liquid membrane Abs: 
2225436,Hill et al. 2013,Gemcitabine-mediated tumour regression and p53-dependent gene expression: implications for colon and pancreatic cancer therapy,,Gemcitabine-mediated tumour regression and p53-dependent gene expression: implications for colon and pancreatic cancer therapy Abs: 
2225435,Wanees et al. 2013,Adsorption Studies on the Removal of Hexavalent Chromium-Contaminated Wastewater Using Activated Carbon and Bentonite,,Adsorption Studies on the Removal of Hexavalent Chromium-Contaminated Wastewater Using Activated Carbon and Bentonite Abs: 
2225434,Lin et al. 2013,Novel pilot-scale washing process and equipment for removing Cr(VI) from contaminated soil,,Novel pilot-scale washing process and equipment for removing Cr(VI) from contaminated soil Abs: 
2225433,Singh et al. 2013,Assay of Some Antimalarial Drugs in Pure Form and in Their Pharmaceutical Preparations with Pyridinium Fluorochromate Reagent,,Assay of Some Antimalarial Drugs in Pure Form and in Their Pharmaceutical Preparations with Pyridinium Fluorochromate Reagent Abs: 
2225432,Lv et al. 2013,Kinetics and Thermodynamics of Cr3+ Adsorption on Modified Palm Thread,,Kinetics and Thermodynamics of Cr3+ Adsorption on Modified Palm Thread Abs: 
2225431,Dwivedi et al. 2013,Glass/epoxy composites and aluminium alloy joint using Kevlar (R) intermediate layer and nanoclay-reinforced epoxy adhesive,,Glass/epoxy composites and aluminium alloy joint using Kevlar (R) intermediate layer and nanoclay-reinforced epoxy adhesive Abs: 
2225430,Marjanovic et al. 2013,Adsorption of chromium (VI) from aqueous solutions onto amine-functionalized natural and acid-activated sepiolites,,Adsorption of chromium (VI) from aqueous solutions onto amine-functionalized natural and acid-activated sepiolites Abs: 
2225429,Rada et al. 2013,Analysis of Electro-Oxidation Suitability for Landfill Leachate Treatment through an Experimental Study,,Analysis of Electro-Oxidation Suitability for Landfill Leachate Treatment through an Experimental Study Abs: 
2225428,Roy et al. 2013,Prediction of distribution of trace elements under Oxy-fuel combustion condition using Victorian brown coals,,Prediction of distribution of trace elements under Oxy-fuel combustion condition using Victorian brown coals Abs: 
2225426,Najafabadi et al. 2013,PRESERVATION OF CAMEL MILK FOR SOMATIC CELL COUNT AND BACTERIOLOGICAL INVESTIGATION,,PRESERVATION OF CAMEL MILK FOR SOMATIC CELL COUNT AND BACTERIOLOGICAL INVESTIGATION Abs: 
2225425,Ding et al. 2013,Crystalline perfection and optical properties of rapid grown KH2PO4 crystal with chromate additive,,Crystalline perfection and optical properties of rapid grown KH2PO4 crystal with chromate additive Abs: 
2225424,Samuel et al. 2013,The differential stress response of adapted chromite mine isolates Bacillus subtilis and Escherichia coli and its impact on bioremediation potential,,The differential stress response of adapted chromite mine isolates Bacillus subtilis and Escherichia coli and its impact on bioremediation potential Abs: 
2225423,Hussain et al. 2013,Retention studies of chromium (VI) from aqueous solution on the surface of a novel carbonaceous material,,Retention studies of chromium (VI) from aqueous solution on the surface of a novel carbonaceous material Abs: 
2225422,Rattanarat et al. 2013,A microfluidic paper-based analytical device for rapid quantification of particulate chromium,,A microfluidic paper-based analytical device for rapid quantification of particulate chromium Abs: 
2225421,Lu et al. 2013,Differential responses to genotoxic agents between induced pluripotent stem cells and tumor cell lines,,Differential responses to genotoxic agents between induced pluripotent stem cells and tumor cell lines Abs: 
2225420,Hayati-Ashtiani 2013,Effects of Nanoporous Montmorillonite Types on the Separation Process of Chromium(III),,Effects of Nanoporous Montmorillonite Types on the Separation Process of Chromium(III) Abs: 
2225419,Poret et al. 2013,Versatile Boron Carbide-Based Energetic Time Delay Compositions,,Versatile Boron Carbide-Based Energetic Time Delay Compositions Abs: 
2225418,Sidiras et al. 2013,Efficient removal of hexavalent chromium from aqueous solutions using autohydrolyzed Scots Pine (Pinus Sylvestris) sawdust as adsorbent,,Efficient removal of hexavalent chromium from aqueous solutions using autohydrolyzed Scots Pine (Pinus Sylvestris) sawdust as adsorbent Abs: 
2225417,Xu et al. 2013,Reduction of Cr(VI) facilitated by biogenetic jarosite and analysis of its influencing factors with response surface methodology,,Reduction of Cr(VI) facilitated by biogenetic jarosite and analysis of its influencing factors with response surface methodology Abs: 
2225416,Mani et al. 2013,Effect of fuels on combustion synthesis of TiO2 - Towards efficient photocatalysts for methylene blue oxidation and Cr (VI) reduction under natural sunlight,,Effect of fuels on combustion synthesis of TiO2 - Towards efficient photocatalysts for methylene blue oxidation and Cr (VI) reduction under natural sunlight Abs: 
2225415,Fu et al. 2013,Chromium removal using resin supported nanoscale zero-valent iron,,Chromium removal using resin supported nanoscale zero-valent iron Abs: 
2225414,Yuan et al. 2013,Chemical Mechanical Polishing Slurries for Chemically Vapor-Deposited Diamond Films,,Chemical Mechanical Polishing Slurries for Chemically Vapor-Deposited Diamond Films Abs: 
2225413,Rhodes et al. 2013,Paramagnetic F-19 NMR and electrospray ionization mass spectrometric studies of substituted pyridine complexes of chromium(III): Models for potential use of F-19 NMR to probe Cr(III)-nucleotide interaction,,Paramagnetic F-19 NMR and electrospray ionization mass spectrometric studies of substituted pyridine complexes of chromium(III): Models for potential use of F-19 NMR to probe Cr(III)-nucleotide interaction Abs: 
2225412,Patnaik et al. 2013,Chromium (VI)-induced hormesis and genotoxicity are mediated through oxidative stress in root cells of Allium cepa L,,Chromium (VI)-induced hormesis and genotoxicity are mediated through oxidative stress in root cells of Allium cepa L Abs: 
2225411,Johnston et al. 2013,True digestive utilization of phosphorus in pea (Pisum sativum) fed to growing pigs,,True digestive utilization of phosphorus in pea (Pisum sativum) fed to growing pigs Abs: 
2225410,Koutahzadeh et al. 2013,Biosorption of hexavalent chromium from aqueous solution by six brown macroalgae,,Biosorption of hexavalent chromium from aqueous solution by six brown macroalgae Abs: 
2225409,Urbano et al. 2013,Exposure of human bronchial epithelial cells to hexavalent chromium [Cr(VI)] decreases the expression of heat shock protein 90 alpha (Hsp90 alpha) and attenuates the transient growth arrest induced by an acute cold shock,,Exposure of human bronchial epithelial cells to hexavalent chromium [Cr(VI)] decreases the expression of heat shock protein 90 alpha (Hsp90 alpha) and attenuates the transient growth arrest induced by an acute cold shock Abs: 
2225408,Jin et al. 2013,The exploration of a new adsorbent as MnO2 modified expanded graphite,,The exploration of a new adsorbent as MnO2 modified expanded graphite Abs: 
2225407,Rangabhashiyam et al. 2013,Biosorption of heavy metals using low cost agricultural by products,,Biosorption of heavy metals using low cost agricultural by products Abs: 
2225406,Sivrikaya et al. 2013,"1,3,5-triazine-triethylenetetramine polymer: an efficient adsorbent for removal of Cr(VI) ions from aqueous solution",,"1,3,5-triazine-triethylenetetramine polymer: an efficient adsorbent for removal of Cr(VI) ions from aqueous solution Abs: "
2225405,Ewais and  Ismail 2013,Mechanism of electron transfer reaction of ternary dipicolinatochromium(III) complex involving oxalate as secondary ligand,,Mechanism of electron transfer reaction of ternary dipicolinatochromium(III) complex involving oxalate as secondary ligand Abs: 
2225404,Qiu et al. 2013,Toward an Understanding of How the Optical Property of Water-Soluble Cationic Polythiophene Derivative Is Altered by the Addition of Salts: The Hofmeister Effect,,Toward an Understanding of How the Optical Property of Water-Soluble Cationic Polythiophene Derivative Is Altered by the Addition of Salts: The Hofmeister Effect Abs: 
2225403,Qin et al. 2013,Highly efficient photocatalytic reduction of Cr(VI) by bismuth hollow nanospheres,,Highly efficient photocatalytic reduction of Cr(VI) by bismuth hollow nanospheres Abs: 
2225402,Mahmood et al. 2013,Potential of newly isolated bacterial strains for simultaneous removal of hexavalent chromium and reactive black-5 azo dye from tannery effluent,,Potential of newly isolated bacterial strains for simultaneous removal of hexavalent chromium and reactive black-5 azo dye from tannery effluent Abs: 
2225401,Li et al. 2013,"Adsorption, concentration, and recovery of aqueous heavy metal ions with the root powder of Eichhornia crassipes",,"Adsorption, concentration, and recovery of aqueous heavy metal ions with the root powder of Eichhornia crassipes Abs: "
2225400,Ullah et al. 2013,Biosorption of chromium onto native and immobilized sugarcane bagasse waste biomass,,Biosorption of chromium onto native and immobilized sugarcane bagasse waste biomass Abs: 
2225399,Gu et al. 2013,Hexavalent chromium synthesized polyaniline nanostructures: Magnetoresistance and electrochemical energy storage behaviors,,Hexavalent chromium synthesized polyaniline nanostructures: Magnetoresistance and electrochemical energy storage behaviors Abs: 
2225398,Shen et al. 2013,Hexavalent chromium detoxification by nonliving Chlorella vulgaris cultivated under tuned conditions,,Hexavalent chromium detoxification by nonliving Chlorella vulgaris cultivated under tuned conditions Abs: 
2225397,Kumar et al. 2013,DBSA doped polyaniline/multi-walled carbon nanotubes composite for high efficiency removal of Cr(VI) from aqueous solution,,DBSA doped polyaniline/multi-walled carbon nanotubes composite for high efficiency removal of Cr(VI) from aqueous solution Abs: 
2225396,Suma et al. 2013,Comparison of Oxidizing Ability of Novel Surfactant-Immobilized Interlayered-Manganate and Chromate Clays over Metal Cation Exchanged Clays Impregnated with Manganate/Chromate,,Comparison of Oxidizing Ability of Novel Surfactant-Immobilized Interlayered-Manganate and Chromate Clays over Metal Cation Exchanged Clays Impregnated with Manganate/Chromate Abs: 
2225395,Srivastava et al. 2013,Ni-Mo-Co ternary alloy as a replacement for hard chrome,,Ni-Mo-Co ternary alloy as a replacement for hard chrome Abs: 
2225394,Huang et al. 2013,Bioanodes/biocathodes formed at optimal potentials enhance subsequent pentachlorophenol degradation and power generation from microbial fuel cells,,Bioanodes/biocathodes formed at optimal potentials enhance subsequent pentachlorophenol degradation and power generation from microbial fuel cells Abs: 
2225393,Sinha et al. 2013,Removal of Cr (VI) by Prosopis cineraria leaf powder-A green remediation,,Removal of Cr (VI) by Prosopis cineraria leaf powder-A green remediation Abs: 
2225392,Souza et al. 2013,Evaluation of chromium concentration in cattle feces using different acid digestion and spectrophotometric quantification techniques,,Evaluation of chromium concentration in cattle feces using different acid digestion and spectrophotometric quantification techniques Abs: 
2225391,Wang et al. 2013,Effect of pH on the removal of Cr(III) and Cr(VI) from aqueous solution by modified polyethyleneimine,,Effect of pH on the removal of Cr(III) and Cr(VI) from aqueous solution by modified polyethyleneimine Abs: 
2225390,Dutta and  Das 2013,Derivatised L-methionine: a new amino polycarboxylate functionality for trace level speciation of chromium by solid-phase extraction,,Derivatised L-methionine: a new amino polycarboxylate functionality for trace level speciation of chromium by solid-phase extraction Abs: 
2225389,Feng et al. 2014,Water and Nutrient Conservation Effects of Different Tillage Treatments in Sloping Fields,,Water and Nutrient Conservation Effects of Different Tillage Treatments in Sloping Fields Abs: 
2225388,Sorouraddin et al. 2013,A simple homemade light emitting diode based photometer for chromium speciation,,A simple homemade light emitting diode based photometer for chromium speciation Abs: 
2225387,Nezamzadeh-Ejhieh and  Shahanshahi 2013,Modification of clinoptilolite nano-particles with hexadecylpyridynium bromide surfactant as an active component of Cr(VI) selective electrode,,Modification of clinoptilolite nano-particles with hexadecylpyridynium bromide surfactant as an active component of Cr(VI) selective electrode Abs: 
2225386,Wei et al. 2013,Decolorization of organic dyes by zero-valent iron in the presence of oxalic acid and influence of photoirradiation and hexavalent chromium,,Decolorization of organic dyes by zero-valent iron in the presence of oxalic acid and influence of photoirradiation and hexavalent chromium Abs: 
2225385,Fu et al. 2013,Insights into environmental remediation of heavy metal and organic pollutants: Simultaneous removal of hexavalent chromium and dye from wastewater by zero-valent iron with ligand-enhanced reactivity,,Insights into environmental remediation of heavy metal and organic pollutants: Simultaneous removal of hexavalent chromium and dye from wastewater by zero-valent iron with ligand-enhanced reactivity Abs: 
2225384,Liu et al. 2013,Mutual promotion mechanism for adsorption of coexisting Cr(III) and Cr(VI) onto titanate nanotubes,,Mutual promotion mechanism for adsorption of coexisting Cr(III) and Cr(VI) onto titanate nanotubes Abs: 
2225383,Xue et al. 2013,Adsorption characterization of Cu(II) from aqueous solution onto basic oxygen furnace slag,,Adsorption characterization of Cu(II) from aqueous solution onto basic oxygen furnace slag Abs: 
2225382,Pagnanelli et al. 2013,Biosorption-mediated reduction of Cr(VI) using heterotrophically-grown Chlorella vulgaris: Active sites and ionic strength effect,,Biosorption-mediated reduction of Cr(VI) using heterotrophically-grown Chlorella vulgaris: Active sites and ionic strength effect Abs: 
2225381,Shaham-Waldmann and  Paz 2013,Beyond charge separation: The effect of coupling between titanium dioxide and CNTs on the adsorption and photocatalytic reduction of Cr(VI),,Beyond charge separation: The effect of coupling between titanium dioxide and CNTs on the adsorption and photocatalytic reduction of Cr(VI) Abs: 
2225380,Velazquez-Pena et al. 2013,Boron-Doped Diamond Electrode Performance in Cr(VI) Reduction Using Synthetic and Plating Wastewater,,Boron-Doped Diamond Electrode Performance in Cr(VI) Reduction Using Synthetic and Plating Wastewater Abs: 
2225379,Lin et al. 2013,"Removal of Cu(II), Cr(III), and Cr(VI) from Aqueous Solution using a Novel Agricultural Waste Adsorbent",,"Removal of Cu(II), Cr(III), and Cr(VI) from Aqueous Solution using a Novel Agricultural Waste Adsorbent Abs: "
2225378,Zhang et al. 2013,Pb(II) and Cr(VI) sorption by biochars pyrolyzed from the municipal wastewater sludge under different heating conditions,,Pb(II) and Cr(VI) sorption by biochars pyrolyzed from the municipal wastewater sludge under different heating conditions Abs: 
2225377,Granados-Correa et al. 2013,Study of Co (II) and Cr (VI) Adsorption from Aqueous Solution by CaCO3,,Study of Co (II) and Cr (VI) Adsorption from Aqueous Solution by CaCO3 Abs: 
2225376,Pan et al. 2013,Adsorption of Cr(III) from acidic solutions by crop straw derived biochars,,Adsorption of Cr(III) from acidic solutions by crop straw derived biochars Abs: 
2225375,Wang et al. 2013,Cr(VI) removal from aqueous solution with bamboo charcoal chemically modified by iron and cobalt with the assistance of microwave,"Bamboo charcoal (BC) was used as starting material to prepare Co-Fe binary oxideloaded adsorbent (Co-Fe-MBC) through its impregnation in Co(NO3)2, FeCl3 and HNO3 solutions simultaneously, followed by microwave heating. The low-cost composite was characterized and used as an adsorbent for Cr(VI) removal from water. The results showed that a cobalt and iron binary oxide (CoFe2O4) was uniformly formed on the BC through redox reactions. The composite exhibited higher surface area (331 m2/g) than that of BC or BC loaded with Fe alone (Fe-MBC). The adsorption of Cr(VI) strongly depended on solution pH, temperature and ionic strength. The adsorption isotherms followed the Langmuir isotherm model well, and the maximum adsorption capacities for Cr(VI) at 288 K and pH 5.0 were 35.7 and 51.7 mg/g for Fe-MBC and Co-Fe-MBC, respectively. The adsorption processes were well fitted by the pseudo second-order kinetic model. Thermodynamic parameters showed that the adsorption of Cr(VI) onto both adsorbents was feasible, spontaneous, and exothermic under the studied conditions. The spent Co-Fe-MBC could be readily regenerated for reuse.","Cr(VI) removal from aqueous solution with bamboo charcoal chemically modified by iron and cobalt with the assistance of microwave Abs: Bamboo charcoal (BC) was used as starting material to prepare Co-Fe binary oxideloaded adsorbent (Co-Fe-MBC) through its impregnation in Co(NO3)2, FeCl3 and HNO3 solutions simultaneously, followed by microwave heating. The low-cost composite was characterized and used as an adsorbent for Cr(VI) removal from water. The results showed that a cobalt and iron binary oxide (CoFe2O4) was uniformly formed on the BC through redox reactions. The composite exhibited higher surface area (331 m2/g) than that of BC or BC loaded with Fe alone (Fe-MBC). The adsorption of Cr(VI) strongly depended on solution pH, temperature and ionic strength. The adsorption isotherms followed the Langmuir isotherm model well, and the maximum adsorption capacities for Cr(VI) at 288 K and pH 5.0 were 35.7 and 51.7 mg/g for Fe-MBC and Co-Fe-MBC, respectively. The adsorption processes were well fitted by the pseudo second-order kinetic model. Thermodynamic parameters showed that the adsorption of Cr(VI) onto both adsorbents was feasible, spontaneous, and exothermic under the studied conditions. The spent Co-Fe-MBC could be readily regenerated for reuse."
2225374,Cao et al. 2013,Kinetics and Mechanism of Cr(VI) Sorption from Aqueous Solution on a Modified Lignocellulosic Material,,Kinetics and Mechanism of Cr(VI) Sorption from Aqueous Solution on a Modified Lignocellulosic Material Abs: 
2225373,Vankar et al. 2013,An assessment and characterization for biosorption efficiency of natural dye waste,,An assessment and characterization for biosorption efficiency of natural dye waste Abs: 
2225372,Pearson and  O'Mullane 2013,Fabrication of Metal-Nanoparticle-Modified Semiconducting Copper- and Silver-TCNQ Materials as Substrates for the Reduction of Chromium(VI) Using Thiosulfate Ions at Ambient Temperature,,Fabrication of Metal-Nanoparticle-Modified Semiconducting Copper- and Silver-TCNQ Materials as Substrates for the Reduction of Chromium(VI) Using Thiosulfate Ions at Ambient Temperature Abs: 
2225370,Farkas et al. 2013,Chromium isotope variations (delta Cr-53/52) in mantle-derived sources and their weathering products: Implications for environmental studies and the evolution of delta Cr-53/52 in the Earth's mantle over geologic time,,Chromium isotope variations (delta Cr-53/52) in mantle-derived sources and their weathering products: Implications for environmental studies and the evolution of delta Cr-53/52 in the Earth's mantle over geologic time Abs: 
2225369,Gagrai et al. 2013,Reduction of Cr(VI) into Cr(III) by Spirulina dead biomass in aqueous solution: Kinetic studies,"Microalga species are potential scavengers of heavy metals. The active functional groups of a number of biomaterials are capable to detoxify Cr(VI) to Cr(III). A 2nd order kinetic model was developed in terms of concentration of protonated acidic groups of Spirulina sp. biomass for the reduction of Cr(VI) into Cr(III). Cr(VI) reduction reaction grounded on the concentration of functional groups was validated over a broad range of pH, temperature and anionic strength. Lower pH favoured Cr(VI) reduction reaction and the experimental results well fitted to the kinetic model. The overall rate constant, kt, decreased logarithmically from 22.7 to 2.8 mM?¹ s?¹ with rise of pH from 0.5 to 6.0. Whereas, k(t) increased nearly by 23% with elevation temperature from 25 to 45 °C. Higher concentration (&gt;0.235 mM) of background anions (Cl?, SO?²? and NO??) was resulted in decreases in k(t) values. The rate constant expression developed can be employed to quantify Cr(VI) reduction into Cr(III) using Spirulina biomass.","Reduction of Cr(VI) into Cr(III) by Spirulina dead biomass in aqueous solution: Kinetic studies Abs: Microalga species are potential scavengers of heavy metals. The active functional groups of a number of biomaterials are capable to detoxify Cr(VI) to Cr(III). A 2nd order kinetic model was developed in terms of concentration of protonated acidic groups of Spirulina sp. biomass for the reduction of Cr(VI) into Cr(III). Cr(VI) reduction reaction grounded on the concentration of functional groups was validated over a broad range of pH, temperature and anionic strength. Lower pH favoured Cr(VI) reduction reaction and the experimental results well fitted to the kinetic model. The overall rate constant, kt, decreased logarithmically from 22.7 to 2.8 mM?¹ s?¹ with rise of pH from 0.5 to 6.0. Whereas, k(t) increased nearly by 23% with elevation temperature from 25 to 45 °C. Higher concentration (&gt;0.235 mM) of background anions (Cl?, SO?²? and NO??) was resulted in decreases in k(t) values. The rate constant expression developed can be employed to quantify Cr(VI) reduction into Cr(III) using Spirulina biomass."
2225368,Shabadi et al. 2014,AZ91C magnesium alloy modified by Cd,,AZ91C magnesium alloy modified by Cd Abs: 
2225367,Shishkina et al. 2013,Effect of chromium compounds on the properties of ion-exchange membranes,,Effect of chromium compounds on the properties of ion-exchange membranes Abs: 
2225366,Lovreglio et al. 2013,A pilot risk assessment study of strontium chromate among painters in the aeronautical industry,,A pilot risk assessment study of strontium chromate among painters in the aeronautical industry Abs: 
2225365,Kalhori et al. 2013,Modeling of adsorption of toxic chromium on natural and surface modified lightweight expanded clay aggregate (LECA),"Lightweight Expanded Clay Aggregate (LECA) modified with an aqueous solution of magnesium chloride MgCI2 and hydrogen peroxide H2O2 was used to remove Cr(VI) from aqueous solutions. The adsorption properties of the used adsorbents were investigated through batch studies, Scanning Electron Microscopy (SEM), X-ray Diffraction (XRD), X-ray Fluorescence Spectroscopy (XRF), and Fourier Transform Infrared (FTIR) spectroscopy. The effect created by magnesium chloride on the modification of the LECA surface was greater than that of hydrogen peroxide solution and showed a substantial increase in the specific surface area which has a value of 76.12 m(2)/g for magnesium chloride modified LECA while the values of 53.72 m(2)/g, and 11.53 m(2)/g were found for hydrogen peroxide modified LECA and natural LECA, respectively. The extent of surface modification with enhanced porosity in modified LECA was apparent from the recorded SEM patterns. XRD and FTIR studies of themodified LECA surface did not show any structural distortion. The adsorption kinetics was found to follow the modified Freundlich kinetic model and the equilibrium data fitted the Sips and Dubinin-Radushkevich equations better than other models. Maximum sorption capacities were found to be 198.39, 218.29 and 236.24 mg/g for natural LECA, surface modified LECA with H2O2 and surface modified LECA with MgCI2, respectively. Adsorbents were found to have only a weak effect on conductivity and turbidity of aqueous solutions. Spent natural and surface modified LECA with MgCI2 was best regenerated with HCI solution, while LECA surface modified with H2O2 was best regenerated with HNO3 concentrated solution. Thermal method showed a lower regeneration percentage for all spent adsorbents. (C) 2013 Elsevier B.V. All rights reserved.","Modeling of adsorption of toxic chromium on natural and surface modified lightweight expanded clay aggregate (LECA) Abs: Lightweight Expanded Clay Aggregate (LECA) modified with an aqueous solution of magnesium chloride MgCI2 and hydrogen peroxide H2O2 was used to remove Cr(VI) from aqueous solutions. The adsorption properties of the used adsorbents were investigated through batch studies, Scanning Electron Microscopy (SEM), X-ray Diffraction (XRD), X-ray Fluorescence Spectroscopy (XRF), and Fourier Transform Infrared (FTIR) spectroscopy. The effect created by magnesium chloride on the modification of the LECA surface was greater than that of hydrogen peroxide solution and showed a substantial increase in the specific surface area which has a value of 76.12 m(2)/g for magnesium chloride modified LECA while the values of 53.72 m(2)/g, and 11.53 m(2)/g were found for hydrogen peroxide modified LECA and natural LECA, respectively. The extent of surface modification with enhanced porosity in modified LECA was apparent from the recorded SEM patterns. XRD and FTIR studies of themodified LECA surface did not show any structural distortion. The adsorption kinetics was found to follow the modified Freundlich kinetic model and the equilibrium data fitted the Sips and Dubinin-Radushkevich equations better than other models. Maximum sorption capacities were found to be 198.39, 218.29 and 236.24 mg/g for natural LECA, surface modified LECA with H2O2 and surface modified LECA with MgCI2, respectively. Adsorbents were found to have only a weak effect on conductivity and turbidity of aqueous solutions. Spent natural and surface modified LECA with MgCI2 was best regenerated with HCI solution, while LECA surface modified with H2O2 was best regenerated with HNO3 concentrated solution. Thermal method showed a lower regeneration percentage for all spent adsorbents. (C) 2013 Elsevier B.V. All rights reserved."
2225364,Wang et al. 2013,Adsorption and desorption characteristics of imidazole-modified silica for chromium(VI),,Adsorption and desorption characteristics of imidazole-modified silica for chromium(VI) Abs: 
2225363,Bulut and  Aksit 2013,"A comparative study on chemical treatment of jute fiber: potassium dichromate, potassium permanganate and sodium perborate trihydrate",,"A comparative study on chemical treatment of jute fiber: potassium dichromate, potassium permanganate and sodium perborate trihydrate Abs: "
2225362,Wang et al. 2013,Solubility and Metastable Zone Width of Sodium Chromate Tetrahydrate,,Solubility and Metastable Zone Width of Sodium Chromate Tetrahydrate Abs: 
2225361,Jiang et al. 2013,"gamma-Fe2O3 Nanoparticles Encapsulated Millimeter-Sized Magnetic Chitosan Beads for Removal of Cr(VI) from Water: Thermodynamics, Kinetics, Regeneration, and Uptake Mechanisms",,"gamma-Fe2O3 Nanoparticles Encapsulated Millimeter-Sized Magnetic Chitosan Beads for Removal of Cr(VI) from Water: Thermodynamics, Kinetics, Regeneration, and Uptake Mechanisms Abs: "
2225360,Lv et al. 2013,Use of High-Pressure CO2 for Concentrating Cr-VI from Electroplating Wastewater by Mg-Al Layered Double Hydroxide,,Use of High-Pressure CO2 for Concentrating Cr-VI from Electroplating Wastewater by Mg-Al Layered Double Hydroxide Abs: 
2225358,Solangi et al. 2013,Transportation of Cr(VI) through calix[4]arene based supported liquid membrane,,Transportation of Cr(VI) through calix[4]arene based supported liquid membrane Abs: 
2225357,Duputel et al. 2013,Citrate adsorption can decrease soluble phosphate concentration in soil: Experimental and modeling evidence,,Citrate adsorption can decrease soluble phosphate concentration in soil: Experimental and modeling evidence Abs: 
2225356,Pimentel Penaloza and  Cruces Martinez 2013,SODIUM COPPER CHLOROPHYLLIN (SCC) INDUCES GENETIC DAMAGE IN POSTMEIOTIC AND SOMATIC WING CELLS OF Drosophila melanogaster,,SODIUM COPPER CHLOROPHYLLIN (SCC) INDUCES GENETIC DAMAGE IN POSTMEIOTIC AND SOMATIC WING CELLS OF Drosophila melanogaster Abs: 
2225355,Dhanalakshmi et al. 2013,Photocatalytic and antimicrobial activities of functionalized silicate sol-gel embedded ZnO-TiO2 nanocomposite materials,,Photocatalytic and antimicrobial activities of functionalized silicate sol-gel embedded ZnO-TiO2 nanocomposite materials Abs: 
2225354,Huang et al. 2013,Visible light photocatalytic reduction of Cr(VI) on Ag3PO4 nanoparticles,,Visible light photocatalytic reduction of Cr(VI) on Ag3PO4 nanoparticles Abs: 
2225353,Jose Alguacil et al. 2013,Transport of Cr(VI) using an advanced membrane technology and (PJMTH(+) NO3-) ionic liquid derived from amine Primene JMT as green chemicals,"The extraction of Cr(VI) from acidic solutions through pseudo-emulsion-based membrane strip dispersion (PEMSD) was conducted in a microporous hydrophobic polyvinylidenedifluoride (PVDF) membrane support and permeation cell. As organic extractant ionic liquids derived from the primary amine Primene JMT in cumene was used. The acidic feed solution containing Cr(VI) was placed in one side of the permeation cell, whereas the pseudo-emulsion of Primene JMT/cumene and acidic solution was placed in the other side of the cell, using a single microporous hydrophobic PVDF membrane support for extraction and stripping. In PEMSD the aqueous acidic (HNO3) solution was dispersed into the organic (Primene JMT/cumene) membrane solution with a mixing arrangement (impeller stirrer) designed to form a strip dispersion. This operation mode provides a constant supply of the ionic liquid extractant/cumene solution to the membrane pores. Various hydrodynamic and chemical parameters, either in the feed or in the pseudo-emulsion phases, were investigated. Results showed that from feed solutions in the pH 3 range, chromium removal efficiencies exceeding 90% are achieving after 3h, whereas chromium recovery in the strip solution is dependent upon the strippant concentration. Furthermore, the performance of this carrier against other extractants was evaluated.","Transport of Cr(VI) using an advanced membrane technology and (PJMTH(+) NO3-) ionic liquid derived from amine Primene JMT as green chemicals Abs: The extraction of Cr(VI) from acidic solutions through pseudo-emulsion-based membrane strip dispersion (PEMSD) was conducted in a microporous hydrophobic polyvinylidenedifluoride (PVDF) membrane support and permeation cell. As organic extractant ionic liquids derived from the primary amine Primene JMT in cumene was used. The acidic feed solution containing Cr(VI) was placed in one side of the permeation cell, whereas the pseudo-emulsion of Primene JMT/cumene and acidic solution was placed in the other side of the cell, using a single microporous hydrophobic PVDF membrane support for extraction and stripping. In PEMSD the aqueous acidic (HNO3) solution was dispersed into the organic (Primene JMT/cumene) membrane solution with a mixing arrangement (impeller stirrer) designed to form a strip dispersion. This operation mode provides a constant supply of the ionic liquid extractant/cumene solution to the membrane pores. Various hydrodynamic and chemical parameters, either in the feed or in the pseudo-emulsion phases, were investigated. Results showed that from feed solutions in the pH 3 range, chromium removal efficiencies exceeding 90% are achieving after 3h, whereas chromium recovery in the strip solution is dependent upon the strippant concentration. Furthermore, the performance of this carrier against other extractants was evaluated."
2225352,Liu et al. 2013,Enhancement of heterogeneous Cr(VI) reduction using clay minerals in the presence of organic carboxylic acids under UV irradiation,,Enhancement of heterogeneous Cr(VI) reduction using clay minerals in the presence of organic carboxylic acids under UV irradiation Abs: 
2225351,Li et al. 2013,Chromium level and intake from Chinese made tea,,Chromium level and intake from Chinese made tea Abs: 
2225350,Senol 2013,Optimal Extractive Separation of Chromium(VI) from Acidic Chloride and Nitrate Media by Commercial Amines: Equilibrium Modeling Through Linear Solvation Energy Relation,,Optimal Extractive Separation of Chromium(VI) from Acidic Chloride and Nitrate Media by Commercial Amines: Equilibrium Modeling Through Linear Solvation Energy Relation Abs: 
2225349,D'Souza et al. 2013,"Bifunctional Titania Float for Metal Ion Reduction and Organics Degradation, via Sunlight",,"Bifunctional Titania Float for Metal Ion Reduction and Organics Degradation, via Sunlight Abs: "
2225348,Kato 2013,Sample Preparation for Estimating Leachable Chromium (VI) in Coal Fly-ash,,Sample Preparation for Estimating Leachable Chromium (VI) in Coal Fly-ash Abs: 
2225347,Radevici et al. 2013,Influence of chromium interaction with native and impurity defects on optical and luminescence properties of ZnSe:Cr crystals,,Influence of chromium interaction with native and impurity defects on optical and luminescence properties of ZnSe:Cr crystals Abs: 
2225346,Ozdes et al. 2014,"ASSESSMENT OF KINETICS, THERMODYNAMICS AND EQUILIBRIUM PARAMETERS OF CR(VI) BIOSORPTION ONTO Pinus brutia TEN",,"ASSESSMENT OF KINETICS, THERMODYNAMICS AND EQUILIBRIUM PARAMETERS OF CR(VI) BIOSORPTION ONTO Pinus brutia TEN Abs: "
2225345,Sadeghi and  Garmroodi 2013,A highly sensitive and selective electrochemical sensor for determination of Cr(VI) in the presence of Cr(III) using modified multi-walled carbon nanotubes/quercetin screen-printed electrode,,A highly sensitive and selective electrochemical sensor for determination of Cr(VI) in the presence of Cr(III) using modified multi-walled carbon nanotubes/quercetin screen-printed electrode Abs: 
2225344,Zhang et al. 2014,One-step hydrothermal synthesis of high-performance visible-light-driven SnS2/SnO2 nanoheterojunction photocatalyst for the reduction of aqueous Cr(VI),"A simple and cost-effective one-step hydrothermal method, which was based on the reactions of tin(IV) chloride pentahydrate and different dosages of thioacetamide in water at 190 degrees C for 6 h, was employed for the synthesis of composition-tunable SnS2/SnO2 nanoheterojunctions (e.g., SnS2/SnO2-A, SnS2/SnO2-B and SnS2/SnO2-C). The photocatalytic properties of the as-synthesized SnS2/SnO2 nanoheterojunctions were tested by the reduction of aqueous Cr(VI) under visible-light (lambda > 420 nm) irradiation. Furthermore, the photocatalytic efficiency of SnS2/SnO2-B was compared with those of PM-SnS2/SnO2 (which denotes the physically mixed SnS2/SnO2 nanocomposite with the same composition as SnS2/SnO2-B) and SnS2 nanoflakes at different dosages of photocatalysts. It was observed that (i) the photocatalytic activities of the as-synthesized SnS2/SnO2 nanoheterojunctions depended on their compositions, and SnS2/SnO2-B with 70 mol% SnS2 displayed the highest photocatalytic activity; (ii) SnS2/SnO2-B invariably exhibited higher photocatalytic efficiencies than PM-SnS2/SnO2 and SnS2 nanoflakes at different dosages of photocatalysts; (iii) the washing with 1 mol/L HNO3 can effectively regenerate the used photocatalyst; (iv) SnS2/SnO2-B exhibited good photocatalytic stability in reuses, with regeneration by 1 mol/L HNO3-washing after each cycle of photocatalytic use; and (v) Cr(VI) was reduced to Cr(III). The possible formation mechanism of SnS2/SnO2 nanoheterojunctions and the reasons accounting for the photocatalytic results were also discussed. (C) 2013 Elsevier B.V. All rights reserved.","One-step hydrothermal synthesis of high-performance visible-light-driven SnS2/SnO2 nanoheterojunction photocatalyst for the reduction of aqueous Cr(VI) Abs: A simple and cost-effective one-step hydrothermal method, which was based on the reactions of tin(IV) chloride pentahydrate and different dosages of thioacetamide in water at 190 degrees C for 6 h, was employed for the synthesis of composition-tunable SnS2/SnO2 nanoheterojunctions (e.g., SnS2/SnO2-A, SnS2/SnO2-B and SnS2/SnO2-C). The photocatalytic properties of the as-synthesized SnS2/SnO2 nanoheterojunctions were tested by the reduction of aqueous Cr(VI) under visible-light (lambda > 420 nm) irradiation. Furthermore, the photocatalytic efficiency of SnS2/SnO2-B was compared with those of PM-SnS2/SnO2 (which denotes the physically mixed SnS2/SnO2 nanocomposite with the same composition as SnS2/SnO2-B) and SnS2 nanoflakes at different dosages of photocatalysts. It was observed that (i) the photocatalytic activities of the as-synthesized SnS2/SnO2 nanoheterojunctions depended on their compositions, and SnS2/SnO2-B with 70 mol% SnS2 displayed the highest photocatalytic activity; (ii) SnS2/SnO2-B invariably exhibited higher photocatalytic efficiencies than PM-SnS2/SnO2 and SnS2 nanoflakes at different dosages of photocatalysts; (iii) the washing with 1 mol/L HNO3 can effectively regenerate the used photocatalyst; (iv) SnS2/SnO2-B exhibited good photocatalytic stability in reuses, with regeneration by 1 mol/L HNO3-washing after each cycle of photocatalytic use; and (v) Cr(VI) was reduced to Cr(III). The possible formation mechanism of SnS2/SnO2 nanoheterojunctions and the reasons accounting for the photocatalytic results were also discussed. (C) 2013 Elsevier B.V. All rights reserved."
2225343,Meichtry et al. 2014,TiO2-photocatalytic transformation of Cr(VI) in the presence of EDTA: Comparison of different commercial photocatalysts and studies by Time Resolved Microwave Conductivity,"The photocatalytic efficiency for Cr(VI) transformation in the presence of etilendiaminetetraacetic acid (EDTA) at pH 2 over various commercial TiO2 samples (Evonik P25, Cristal Global PC50, PC100 and PC500, Hombikat UV100, Fluka and Kemira S230) was evaluated. The decay was adjusted to a pseudo-first order kinetics in all cases and the photocatalytic activity of the samples was estimated from the kinetic constants. The order of the photocatalytic activity was PC500 a UV100 > P25 a PC100 > S230 a PC50 a","TiO2-photocatalytic transformation of Cr(VI) in the presence of EDTA: Comparison of different commercial photocatalysts and studies by Time Resolved Microwave Conductivity Abs: The photocatalytic efficiency for Cr(VI) transformation in the presence of etilendiaminetetraacetic acid (EDTA) at pH 2 over various commercial TiO2 samples (Evonik P25, Cristal Global PC50, PC100 and PC500, Hombikat UV100, Fluka and Kemira S230) was evaluated. The decay was adjusted to a pseudo-first order kinetics in all cases and the photocatalytic activity of the samples was estimated from the kinetic constants. The order of the photocatalytic activity was PC500 a UV100 > P25 a PC100 > S230 a PC50 a"
2225342,Corbel et al. 2013,Study of a Classical Strobe Composition,,Study of a Classical Strobe Composition Abs: 
2225341,Taziki et al. 2013,Robust Ionic Liquid-Based Dispersive Liquid-Liquid Microextraction Method for Determination of Chromium(VI) in Saline Solutions,,Robust Ionic Liquid-Based Dispersive Liquid-Liquid Microextraction Method for Determination of Chromium(VI) in Saline Solutions Abs: 
2225340,Pang et al. 2013,Conductive polymer-mediated Cr(VI) reduction in a dual-chamber microbial fuel cell under neutral conditions,,Conductive polymer-mediated Cr(VI) reduction in a dual-chamber microbial fuel cell under neutral conditions Abs: 
2225339,Zhou et al. 2013,Production of a monoclonal antibody and development of an immunoassay for detection of Cr(III) in water samples,,Production of a monoclonal antibody and development of an immunoassay for detection of Cr(III) in water samples Abs: 
2225338,Yewalkar et al. 2013,Effect of chromate on photosynthesis in Cr(VI)-resistant Chlorella,,Effect of chromate on photosynthesis in Cr(VI)-resistant Chlorella Abs: 
2225337,Leung et al. 2013,An Amyloid-Fibril-Based Colorimetric Nanosensor for Rapid and Sensitive Chromium(VI) Detection,,An Amyloid-Fibril-Based Colorimetric Nanosensor for Rapid and Sensitive Chromium(VI) Detection Abs: 
2225336,Sugashini et al. 2013,Adsorption and desorption studies on the performance of Fe-loaded chitosan carbonized rice husk for metal ion removal,,Adsorption and desorption studies on the performance of Fe-loaded chitosan carbonized rice husk for metal ion removal Abs: 
2225335,Liu et al. 2013,Enhanced chitosan beads-supported Fe-0-nanoparticles for removal of heavy metals from electroplating wastewater in permeable reactive barriers,,Enhanced chitosan beads-supported Fe-0-nanoparticles for removal of heavy metals from electroplating wastewater in permeable reactive barriers Abs: 
2225334,Javadian et al. 2013,Removal of Cr(VI) by modified brown algae Sargassum bevanom from aqueous solution and industrial wastewater,,Removal of Cr(VI) by modified brown algae Sargassum bevanom from aqueous solution and industrial wastewater Abs: 
2225333,Sayin and  Karakas 2013,Quantum chemical studies on the some inorganic corrosion inhibitors,"Some quantum chemical parameters were calculated by using Hartree-Fock (HF) approximation, Density Functional Theory (DFT/B3LYP) and Moller Plesset perturbation theory (MP3) methods at LANL2DZ, LANL2MB and SOD levels in gas phase and water for dichromate (Cr2O72-), chromate (CrO42-), tungstate (WO42-), molybdate (MoO42-), nitrite (NO2-) and nitrate (NO3-) which are used as inorganic corrosion inhibitors. All theoretical results and experimental inhibition efficiencies of inhibitors were subjected to correlation analyses. In a summary, MP3/SDD level in water was found as the best level. In this level, the inhibition efficiency ranking was found as CrO42- > WO42- > MoO42- > Cr2O72- > NO2- approximate to NO3-. (C) 2013 Elsevier Ltd. All rights reserved.","Quantum chemical studies on the some inorganic corrosion inhibitors Abs: Some quantum chemical parameters were calculated by using Hartree-Fock (HF) approximation, Density Functional Theory (DFT/B3LYP) and Moller Plesset perturbation theory (MP3) methods at LANL2DZ, LANL2MB and SOD levels in gas phase and water for dichromate (Cr2O72-), chromate (CrO42-), tungstate (WO42-), molybdate (MoO42-), nitrite (NO2-) and nitrate (NO3-) which are used as inorganic corrosion inhibitors. All theoretical results and experimental inhibition efficiencies of inhibitors were subjected to correlation analyses. In a summary, MP3/SDD level in water was found as the best level. In this level, the inhibition efficiency ranking was found as CrO42- > WO42- > MoO42- > Cr2O72- > NO2- approximate to NO3-. (C) 2013 Elsevier Ltd. All rights reserved."
2225332,El-Sherif et al. 2013,Polymeric nanofibers for the removal of Cr(III) from tannery waste water,,Polymeric nanofibers for the removal of Cr(III) from tannery waste water Abs: 
2225331,Mahajan et al. 2013,Cr(VI) Imposed Toxicity in Maize Seedlings Assessed in Terms of Disruption in Carbohydrate Metabolism,,Cr(VI) Imposed Toxicity in Maize Seedlings Assessed in Terms of Disruption in Carbohydrate Metabolism Abs: 
2225330,Qi et al. 2014,Synthesis of Magnetic Expanded Graphite and Its Application to Remove Cr(VI) From Wastewater,,Synthesis of Magnetic Expanded Graphite and Its Application to Remove Cr(VI) From Wastewater Abs: 
2225329,Sarkar et al. 2013,Analysis of Bio-Sorption of Cr(VI) onto Raw Rice Husk by a Hybrid Theoretical Model Using Results of Batch Experiments,,Analysis of Bio-Sorption of Cr(VI) onto Raw Rice Husk by a Hybrid Theoretical Model Using Results of Batch Experiments Abs: 
2225328,Siidra et al. 2013,Cr-VI -> Cr-V Transition in Uranyl Chromium Compounds: Synthesis and High-temperature X-ray Diffraction Study of Cs-2[(UO2)(2)(CrO4)(3)],,Cr-VI -> Cr-V Transition in Uranyl Chromium Compounds: Synthesis and High-temperature X-ray Diffraction Study of Cs-2[(UO2)(2)(CrO4)(3)] Abs: 
2225327,de Souza et al. 2013,Modeling of trivalent chromium speciation in binding sites of marine macroalgae Sargassum Cymosum,,Modeling of trivalent chromium speciation in binding sites of marine macroalgae Sargassum Cymosum Abs: 
2225326,Petala et al. 2013,Nanoscale zero-valent iron supported on mesoporous silica: Characterization and reactivity for Cr(VI) removal from aqueous solution,,Nanoscale zero-valent iron supported on mesoporous silica: Characterization and reactivity for Cr(VI) removal from aqueous solution Abs: 
2225325,Chen et al. 2013,Elucidating the mechanism of Cr(VI) formation upon the interaction with metal oxides during coal oxy-fuel combustion,,Elucidating the mechanism of Cr(VI) formation upon the interaction with metal oxides during coal oxy-fuel combustion Abs: 
2225324,El-Sheikh et al. 2013,Separation and flame atomic absorption spectrometric determination of total chromium and chromium (III) in phosphate rock used for production of fertilizer,"Due to the commercial value of phosphate rock (PR) as a fertilizer precursor, it is necessary to investigate its heavy metals content. Chromium (Cr) may present as Cr(III) or Cr(VI) in PR; but quantitative differentiation between them is not an easy task. This is due to possible interconversion of Cr species during the digestion/leaching process. In this work, ultrasound digestion (USD) of PR was optimized (300 mg PR, 4.0 mL of 4.0 mol L(-1) nitric acid, 15 min sonication) for the sake of leaching Cr species prior to their determination by flame atomic absorption spectroscopy. Using multi-walled carbon nanotube (MWCNT) as adsorbent, solid phase extraction (SPE) was used to separate Cr(III) from the digestate at pH 9, while total Cr was estimated after reducing Cr(VI) into Cr(III). The optimum USD/SPE method gave LOQ and LOD of Cr(III) of 0.96 mg kg(-1) and 0.288 mg kg(-1), respectively. The method sensitivity was 1.44×10(-3) AU kg mg(-1) within the studied Cr concentration range (5-400 mg kg(-1)). The USD/SPE method was validated by analyzing lake sediments LKSD-4 certified reference material, and by comparison with classical digestion method (CD). Application of USD/SPE on Jordanian PR samples gave total Cr rang 29.1-122.0 mg kg(-1) (±1.4-6.3), while Cr(III) ranged between 23.8 and 101.7 mg kg(-1) (±1.3-5.5). AFPC Rock Check Program samples gave total Cr range 238.9-394.7 mg kg(-1) (±11.5-24.1), while Cr(III) ranged between 202.4 and 335.8 mg kg(-1) (±11.4-18.3). These results were very close to the results obtained by the CD method.","Separation and flame atomic absorption spectrometric determination of total chromium and chromium (III) in phosphate rock used for production of fertilizer Abs: Due to the commercial value of phosphate rock (PR) as a fertilizer precursor, it is necessary to investigate its heavy metals content. Chromium (Cr) may present as Cr(III) or Cr(VI) in PR; but quantitative differentiation between them is not an easy task. This is due to possible interconversion of Cr species during the digestion/leaching process. In this work, ultrasound digestion (USD) of PR was optimized (300 mg PR, 4.0 mL of 4.0 mol L(-1) nitric acid, 15 min sonication) for the sake of leaching Cr species prior to their determination by flame atomic absorption spectroscopy. Using multi-walled carbon nanotube (MWCNT) as adsorbent, solid phase extraction (SPE) was used to separate Cr(III) from the digestate at pH 9, while total Cr was estimated after reducing Cr(VI) into Cr(III). The optimum USD/SPE method gave LOQ and LOD of Cr(III) of 0.96 mg kg(-1) and 0.288 mg kg(-1), respectively. The method sensitivity was 1.44×10(-3) AU kg mg(-1) within the studied Cr concentration range (5-400 mg kg(-1)). The USD/SPE method was validated by analyzing lake sediments LKSD-4 certified reference material, and by comparison with classical digestion method (CD). Application of USD/SPE on Jordanian PR samples gave total Cr rang 29.1-122.0 mg kg(-1) (±1.4-6.3), while Cr(III) ranged between 23.8 and 101.7 mg kg(-1) (±1.3-5.5). AFPC Rock Check Program samples gave total Cr range 238.9-394.7 mg kg(-1) (±11.5-24.1), while Cr(III) ranged between 202.4 and 335.8 mg kg(-1) (±11.4-18.3). These results were very close to the results obtained by the CD method."
2225323,Jiang et al. 2013,Magnetic solid-phase extraction combined with graphite furnace atomic absorption spectrometry for speciation of Cr(III) and Cr(VI) in environmental waters,,Magnetic solid-phase extraction combined with graphite furnace atomic absorption spectrometry for speciation of Cr(III) and Cr(VI) in environmental waters Abs: 
2225322,Takagi et al. 2013,Hexavalent hydrogen complex in hypothetical Y2CrH6,,Hexavalent hydrogen complex in hypothetical Y2CrH6 Abs: 
2225321,Kang et al. 2013,"Adsorption isotherm, kinetic and thermodynamic studies of activated carbon prepared from Garcinia mangostana shell",,"Adsorption isotherm, kinetic and thermodynamic studies of activated carbon prepared from Garcinia mangostana shell Abs: "
2225320,Kallarackel et al. 2013,"Thermodynamic Properties of LaCrO4, La2CrO6, and La2Cr3O12, and Subsolidus Phase Relations in the System Lanthanum-Chromium-Oxygen",,"Thermodynamic Properties of LaCrO4, La2CrO6, and La2Cr3O12, and Subsolidus Phase Relations in the System Lanthanum-Chromium-Oxygen Abs: "
2225319,Zhang et al. 2013,Dispersive liquid liquid microextraction combined with electrothermal vaporization inductively coupled plasma mass spectrometry for the speciation of inorganic selenium in environmental water samples,,Dispersive liquid liquid microextraction combined with electrothermal vaporization inductively coupled plasma mass spectrometry for the speciation of inorganic selenium in environmental water samples Abs: 
2225318,Koc et al. 2013,Detection of the of Effects of Hexavalent Chromium by Histopathological and Electrophoretic Methods on Capoeta capoeta (Guldenstaedt 1773) and Squalius cephalus (Linnaeus 1758),,Detection of the of Effects of Hexavalent Chromium by Histopathological and Electrophoretic Methods on Capoeta capoeta (Guldenstaedt 1773) and Squalius cephalus (Linnaeus 1758) Abs: 
2225317,Sarkar et al. 2013,Simultaneous Adsorption of Tri- and Hexavalent Chromium by Organoclay Mixtures,,Simultaneous Adsorption of Tri- and Hexavalent Chromium by Organoclay Mixtures Abs: 
2225316,Choppala et al. 2013,Comparative Sorption and Mobility of Cr(III) and Cr(VI) Species in a Range of Soils: Implications to Bioavailability,,Comparative Sorption and Mobility of Cr(III) and Cr(VI) Species in a Range of Soils: Implications to Bioavailability Abs: 
2225315,Cohen and  Ozawa 2013,Microbial Sulfate Reduction and Biogeochemistry of Arsenic and Chromium Oxyanions in Anaerobic Bioreactors,"A pilot-scale anaerobic bioreactor with high levels of microbial sulfate reduction, known to be capable of removing cationic metals from a metal- and acid-contaminated waste stream, was utilized to determine if the system would be effective in removing metals in the form of oxyanions such as arsenate and chromate. The system removed 90 % to &gt;99 % of the arsenic and between 86 % and 94 % of the chromium from a waste stream containing 5 mg/L of each. Cadmium, copper, iron, lead, and zinc also were removed. An equilibrium geochemistry computer modeling code, MINTEQAK, modified from MINTEQA2, was used for the chemical modeling of processes in the bioreactor. Experimental evidence on the chemical and biological reduction of arsenic and chromium and fluorescent diffraction analysis of precipitates support the following hypotheses: the primary removal process for chromium was the reduction of Cr(VI) to Cr(III) by sulfides, followed by precipitation of chromium hydroxide [Cr(OH)(3(s))]; removal of arsenic was by direct microbial enzymatic reduction of As(V) to As(III) followed by precipitation of arsenic sulfides (As2S3 or AsS). Experimental evidence and modeling with MINTEQAK confirmed that 90 % to 95 % of the removal of arsenic and chromium occurred in the first quarter volume of the bioreactor. Additional removal of arsenic and chromium occurred in the remaining volume of the bioreactor. The use of a sulfate reduction-based anaerobic treatment system was effective for metal-laden wastewater with elevated concentrations of arsenic and chromium.","Microbial Sulfate Reduction and Biogeochemistry of Arsenic and Chromium Oxyanions in Anaerobic Bioreactors Abs: A pilot-scale anaerobic bioreactor with high levels of microbial sulfate reduction, known to be capable of removing cationic metals from a metal- and acid-contaminated waste stream, was utilized to determine if the system would be effective in removing metals in the form of oxyanions such as arsenate and chromate. The system removed 90 % to &gt;99 % of the arsenic and between 86 % and 94 % of the chromium from a waste stream containing 5 mg/L of each. Cadmium, copper, iron, lead, and zinc also were removed. An equilibrium geochemistry computer modeling code, MINTEQAK, modified from MINTEQA2, was used for the chemical modeling of processes in the bioreactor. Experimental evidence on the chemical and biological reduction of arsenic and chromium and fluorescent diffraction analysis of precipitates support the following hypotheses: the primary removal process for chromium was the reduction of Cr(VI) to Cr(III) by sulfides, followed by precipitation of chromium hydroxide [Cr(OH)(3(s))]; removal of arsenic was by direct microbial enzymatic reduction of As(V) to As(III) followed by precipitation of arsenic sulfides (As2S3 or AsS). Experimental evidence and modeling with MINTEQAK confirmed that 90 % to 95 % of the removal of arsenic and chromium occurred in the first quarter volume of the bioreactor. Additional removal of arsenic and chromium occurred in the remaining volume of the bioreactor. The use of a sulfate reduction-based anaerobic treatment system was effective for metal-laden wastewater with elevated concentrations of arsenic and chromium."
2225314,Plaza Cazon et al. 2013,Dynamic Cr(III) uptake by Macrocystis pyrifera and Undaria pinnatifida biomasses,,Dynamic Cr(III) uptake by Macrocystis pyrifera and Undaria pinnatifida biomasses Abs: 
2225313,Karimi et al. 2013,Speciation Analysis of Cr(III) and Cr(VI) after Solid Phase Extraction Using Modified Magnetite Nanoparticles,,Speciation Analysis of Cr(III) and Cr(VI) after Solid Phase Extraction Using Modified Magnetite Nanoparticles Abs: 
2225312,Sadyrbaeva 2013,Electrodialytic Recovery of Chromium(VI) from Hydrochloric Acid Solutions with Liquid Membranes Based on Tri-n-Octylamine,,Electrodialytic Recovery of Chromium(VI) from Hydrochloric Acid Solutions with Liquid Membranes Based on Tri-n-Octylamine Abs: 
2225311,Dadvand et al. 2013,Electrodeposition of cobalt-tungsten alloys from alkaline citrate containing bath as alternative for chromium hexavalent replacement,,Electrodeposition of cobalt-tungsten alloys from alkaline citrate containing bath as alternative for chromium hexavalent replacement Abs: 
2225310,Cheng et al. 2014,Effect of air-drying and oven-drying treatment on Cr(VI) content and Cr bond forms in soil,,Effect of air-drying and oven-drying treatment on Cr(VI) content and Cr bond forms in soil Abs: 
2225309,Kasian et al. 2013,Anodic oxidation of Cr3+ ions in a chromium electroplating bath on Pt and composite TiOx/PtOy,,Anodic oxidation of Cr3+ ions in a chromium electroplating bath on Pt and composite TiOx/PtOy Abs: 
2225308,Li and  Swain 2013,Formation and Structure of Trivalent Chromium Process Coatings on Aluminum Alloys 6061 and 7075,,Formation and Structure of Trivalent Chromium Process Coatings on Aluminum Alloys 6061 and 7075 Abs: 
2225306,de Godoi et al. 2013,An XPS study of chromate and vanadate sorption mechanism by chitosan membrane containing copper nanoparticles,,An XPS study of chromate and vanadate sorption mechanism by chitosan membrane containing copper nanoparticles Abs: 
2225305,Sun et al. 2013,Synthesis of polyethylenimine-functionalized poly(glycidyl methacrylate) magnetic microspheres and their excellent Cr(VI) ion removal properties,"Micron-sized polyethylenimine-functionalized poly(glycidyl methacrylate) superparamagnetic microspheres (m-PGMA-PEI) were prepared by a process involving: (1) synthesis of PGMA microspheres using the dispersion polymerization method; (2) ring-opening reaction of epoxy groups on PGMA microspheres with ethylenediamine (EDA) to yield amino groups; (3) in situ coprecipitation of Fe3O4 nanoparticles into the pores of microspheres; (4) Michael addition of amino groups with methyl acrylate (MA) to yield ester groups; and (5) amidation of the terminal ester groups with polyethylenimine (PEI). Once generated, the resulting m-PGMA-PEI microspheres were tested for their ability to remove Cr(VI) from an aqueous solution in batch experiments. The results demonstrated that Cr(VI) adsorption was significantly pH dependent. The optimized pH value was 2.0. The adsorption isotherm of the adsorbent fit the Langmuir model, with the maximum adsorption capacity of 492.61 mg/g. The Cr(VI) adsorption rate was rapid, and the adsorption reached equilibrium within 15 min. The thermodynamic parameters (Delta G(0), Delta H-0, Delta S-0) demonstrated that the adsorption process was endothermic and spontaneous in nature. The presence of the coexisting anions involving Cl-, NO3-, H2PO4- and HPO42- had no remarkable influence on Cr(VI) adsorption except SO42-. The regeneration study proved that the m-PGMA-PEI microspheres could be repeatedly utilized with no significant loss of adsorption efficiency. (C) 2013 Elsevier B.V. All rights reserved.","Synthesis of polyethylenimine-functionalized poly(glycidyl methacrylate) magnetic microspheres and their excellent Cr(VI) ion removal properties Abs: Micron-sized polyethylenimine-functionalized poly(glycidyl methacrylate) superparamagnetic microspheres (m-PGMA-PEI) were prepared by a process involving: (1) synthesis of PGMA microspheres using the dispersion polymerization method; (2) ring-opening reaction of epoxy groups on PGMA microspheres with ethylenediamine (EDA) to yield amino groups; (3) in situ coprecipitation of Fe3O4 nanoparticles into the pores of microspheres; (4) Michael addition of amino groups with methyl acrylate (MA) to yield ester groups; and (5) amidation of the terminal ester groups with polyethylenimine (PEI). Once generated, the resulting m-PGMA-PEI microspheres were tested for their ability to remove Cr(VI) from an aqueous solution in batch experiments. The results demonstrated that Cr(VI) adsorption was significantly pH dependent. The optimized pH value was 2.0. The adsorption isotherm of the adsorbent fit the Langmuir model, with the maximum adsorption capacity of 492.61 mg/g. The Cr(VI) adsorption rate was rapid, and the adsorption reached equilibrium within 15 min. The thermodynamic parameters (Delta G(0), Delta H-0, Delta S-0) demonstrated that the adsorption process was endothermic and spontaneous in nature. The presence of the coexisting anions involving Cl-, NO3-, H2PO4- and HPO42- had no remarkable influence on Cr(VI) adsorption except SO42-. The regeneration study proved that the m-PGMA-PEI microspheres could be repeatedly utilized with no significant loss of adsorption efficiency. (C) 2013 Elsevier B.V. All rights reserved."
2225304,Luo et al. 2013,Manganese dioxide/iron oxide/acid Oxidized multi-walled carbon nanotube magnetic nanocomposite for enhanced hexavalent chromium removal,,Manganese dioxide/iron oxide/acid Oxidized multi-walled carbon nanotube magnetic nanocomposite for enhanced hexavalent chromium removal Abs: 
2225303,Wang et al. 2013,Determination of trace chromium (VI) using a hollow-core metal-cladding optical waveguide sensor,,Determination of trace chromium (VI) using a hollow-core metal-cladding optical waveguide sensor Abs: 
2225302,Yu et al. 2013,Synthesis of poly (m-phenylenediamine) with improved properties and superior prospect for Cr(VI) removal,,Synthesis of poly (m-phenylenediamine) with improved properties and superior prospect for Cr(VI) removal Abs: 
2225301,Kanchinadham et al. 2013,A Preliminary Study on Leachability of Chromium from a Contaminated Site,,A Preliminary Study on Leachability of Chromium from a Contaminated Site Abs: 
2225300,Gottipati and  Mishra 2013,Simultaneous Removal of Trivalent and Hexavalent Chromium by Activated Carbon: Effect of Solution pH and Pore Size Distribution of Adsorbent,,Simultaneous Removal of Trivalent and Hexavalent Chromium by Activated Carbon: Effect of Solution pH and Pore Size Distribution of Adsorbent Abs: 
2225299,Marjanovic et al. 2013,Functionalization of thermo-acid activated sepiolite by amine-silane and mercapto-silane for chromium(VI) adsorption from aqueous solutions,,Functionalization of thermo-acid activated sepiolite by amine-silane and mercapto-silane for chromium(VI) adsorption from aqueous solutions Abs: 
2225298,Demim et al. 2013,Cadmium and nickel: Assessment of the physiological effects and heavy metal removal using a response surface approach by L. gibba,,Cadmium and nickel: Assessment of the physiological effects and heavy metal removal using a response surface approach by L. gibba Abs: 
2225297,Panneerselvam et al. 2013,Potential of Novel Bacterial Consortium for the Remediation of Chromium Contamination,"This study was aimed to examine the efficiency of a novel bacterial consortium on the reduction of toxic hexavalent chromium [Cr(VI)] to non-toxic trivalent Cr [Cr(III)]. Six Cr(VI)-resistant bacteria (IS1-IS6) were isolated from a tannery waste disposal site at Mount Barker, South Australia, of which three viz., IS1, IS2 and IS3 were selected based on Cr(VI) reduction ability in minimal salt medium. The isolates were identified as Bacillus endophyticus (IS1), Microbacterium paraoxydans (IS2) and Bacillus simplex (IS3) by 16S rRNA gene sequencing. All three isolates were able to tolerate chromium (Cr(VI), 300-400 mg L-1), arsenic (As(V), 1,000 mg L-1), copper (Cu(II), 300-400 mg L-1) and lead (Pb(II), 1,000 mg L-1). The isolates were evaluated both as an individual and as a consortia for Cr(VI) reduction inminimal salt medium and storm water, both spiked with 100 mg Cr(VI) L-1. In both cases, the rate of Cr(VI) reduction was found to be significantly higher in the bacterial consortium inoculation (t(1/2) = 8.45 for minimal salt medium; 6.02 h for storm water), compared to inoculation with individual isolates (t = 53.3-115.5 h for minimal salt medium; 8.77-9.76 h for storm water). The rate of Cr(VI) reduction in both minimal salt medium and storm water was found to be higher in bacterial consortium inoculation (IS1+IS2+IS3) than in individual isolate inoculation. This experiment demonstrated that bacterial consortium prepared by using B. endophyticus, M. paraoxydans and B. simplex was more effective in Cr(VI) detoxification than application of individual bacterium. This experiment also proved that a bacterial consortium was more effective in Cr(VI) detoxification than the application of individual bacterial strain.","Potential of Novel Bacterial Consortium for the Remediation of Chromium Contamination Abs: This study was aimed to examine the efficiency of a novel bacterial consortium on the reduction of toxic hexavalent chromium [Cr(VI)] to non-toxic trivalent Cr [Cr(III)]. Six Cr(VI)-resistant bacteria (IS1-IS6) were isolated from a tannery waste disposal site at Mount Barker, South Australia, of which three viz., IS1, IS2 and IS3 were selected based on Cr(VI) reduction ability in minimal salt medium. The isolates were identified as Bacillus endophyticus (IS1), Microbacterium paraoxydans (IS2) and Bacillus simplex (IS3) by 16S rRNA gene sequencing. All three isolates were able to tolerate chromium (Cr(VI), 300-400 mg L-1), arsenic (As(V), 1,000 mg L-1), copper (Cu(II), 300-400 mg L-1) and lead (Pb(II), 1,000 mg L-1). The isolates were evaluated both as an individual and as a consortia for Cr(VI) reduction inminimal salt medium and storm water, both spiked with 100 mg Cr(VI) L-1. In both cases, the rate of Cr(VI) reduction was found to be significantly higher in the bacterial consortium inoculation (t(1/2) = 8.45 for minimal salt medium; 6.02 h for storm water), compared to inoculation with individual isolates (t = 53.3-115.5 h for minimal salt medium; 8.77-9.76 h for storm water). The rate of Cr(VI) reduction in both minimal salt medium and storm water was found to be higher in bacterial consortium inoculation (IS1+IS2+IS3) than in individual isolate inoculation. This experiment demonstrated that bacterial consortium prepared by using B. endophyticus, M. paraoxydans and B. simplex was more effective in Cr(VI) detoxification than application of individual bacterium. This experiment also proved that a bacterial consortium was more effective in Cr(VI) detoxification than the application of individual bacterial strain."
2225296,Ye et al. 2014,A highly selective turn-on fluorescent chemodosimeter for Cr(VI) and its application in living cell imaging,,A highly selective turn-on fluorescent chemodosimeter for Cr(VI) and its application in living cell imaging Abs: 
2225295,Mukherjee et al. 2013,Selection of Promoter and Mice liar Catalyst for Chromic Acid oxidation of Tartaric Acid in Aqueous Medium at Room Temperature,,Selection of Promoter and Mice liar Catalyst for Chromic Acid oxidation of Tartaric Acid in Aqueous Medium at Room Temperature Abs: 
2225294,Ziagova et al. 2014,Optimization of cultural conditions of Arthrobacter sp Sphe3 for growth-associated chromate(VI) reduction in free and immobilized cell systems,,Optimization of cultural conditions of Arthrobacter sp Sphe3 for growth-associated chromate(VI) reduction in free and immobilized cell systems Abs: 
2225293,Ghosh et al. 2014,Suitable combination of promoter and micellar catalyst for kilo fold rate acceleration on propanol to propionaldehyde conversion in aqueous media,,Suitable combination of promoter and micellar catalyst for kilo fold rate acceleration on propanol to propionaldehyde conversion in aqueous media Abs: 
2225292,Sankararamakrishnan et al. 2014,Composite nanofloral clusters of carbon nanotubes and activated alumina: An efficient sorbent for heavy metal removal,,Composite nanofloral clusters of carbon nanotubes and activated alumina: An efficient sorbent for heavy metal removal Abs: 
2225291,Mohan et al. 2014,Cadmium and lead remediation using magnetic oak wood and oak bark fast pyrolysis bio-chars,,Cadmium and lead remediation using magnetic oak wood and oak bark fast pyrolysis bio-chars Abs: 
2225290,Sikder et al. 2014,Preparation and characterization of chitosan-caboxymethyl-beta-cyclodextrin entrapped nanozero-valent iron composite for Cu (II) and Cr (IV) removal from wastewater,,Preparation and characterization of chitosan-caboxymethyl-beta-cyclodextrin entrapped nanozero-valent iron composite for Cu (II) and Cr (IV) removal from wastewater Abs: 
2225289,Li et al. 2014,Removal of trivalent chromium in the complex state of trivalent chromium passivation wastewater,,Removal of trivalent chromium in the complex state of trivalent chromium passivation wastewater Abs: 
2225288,Zhou et al. 2013,Synthesis and adsorption behaviors of poly(2-(dimethylamino)ethyl methacrylate) brushes on silica particles by surface-initiated atom transfer radical polymerization,,Synthesis and adsorption behaviors of poly(2-(dimethylamino)ethyl methacrylate) brushes on silica particles by surface-initiated atom transfer radical polymerization Abs: 
2225287,Zhao et al. 2013,Separation of tungsten and molybdenum using macroporous resin: Equilibrium adsorption for single and binary systems,,Separation of tungsten and molybdenum using macroporous resin: Equilibrium adsorption for single and binary systems Abs: 
2225286,Dey and  Paul 2014,Reduction of Hexavalent Chromium by Immobilized Viable Cells of Arthrobacter sp SUK 1201,,Reduction of Hexavalent Chromium by Immobilized Viable Cells of Arthrobacter sp SUK 1201 Abs: 
2225284,Saputro et al. 2014,Speciation of dissolved chromium and the mechanisms controlling its concentration in natural water,,Speciation of dissolved chromium and the mechanisms controlling its concentration in natural water Abs: 
2225283,Vodyanitskii 2013,Determination of the oxidation states of metals and metalloids: An analytical review,"The hazard of many heavy metals/metalloids in the soil depends on their oxidation state. The problem of determining the oxidation state has been solved due to the use of synchrotron radiation methods with the analysis of the X-ray absorption near-edge structure (XANES). The determination of the oxidation state is of special importance for some hazardous heavy elements (arsenic, antimony, selenium, chromium, uranium, and vanadium). The mobility and hazard of each of these elements depend on its oxidation state. The mobilities are higher at lower oxidation states of As, Cr, V, and Se and at higher oxidation states of Sb and U. The determination of the oxidation state of arsenic has allowed revealing its fixation features in the rhizosphere of hydrophytes. The known oxidation states of chromium and uranium are used for the retention of these elements on geochemical barriers. Different oxidation states have been established for vanadium displacing iron in goethite. The determination of the oxidation state of manganese in the rhizosphere and the photosynthetic apparatus of plants is of special importance for agricultural chemists.","Determination of the oxidation states of metals and metalloids: An analytical review Abs: The hazard of many heavy metals/metalloids in the soil depends on their oxidation state. The problem of determining the oxidation state has been solved due to the use of synchrotron radiation methods with the analysis of the X-ray absorption near-edge structure (XANES). The determination of the oxidation state is of special importance for some hazardous heavy elements (arsenic, antimony, selenium, chromium, uranium, and vanadium). The mobility and hazard of each of these elements depend on its oxidation state. The mobilities are higher at lower oxidation states of As, Cr, V, and Se and at higher oxidation states of Sb and U. The determination of the oxidation state of arsenic has allowed revealing its fixation features in the rhizosphere of hydrophytes. The known oxidation states of chromium and uranium are used for the retention of these elements on geochemical barriers. Different oxidation states have been established for vanadium displacing iron in goethite. The determination of the oxidation state of manganese in the rhizosphere and the photosynthetic apparatus of plants is of special importance for agricultural chemists."
2225282,Wilson et al. 2014,Analysis of heat-labile sites generated by reactions of depleted uranium and ascorbate in plasmid DNA,"The goal of this study was to characterize how depleted uranium (DU) causes DNA damage. Procedures were developed to assess the ability of organic and inorganic DNA adducts to convert to single-strand breaks (SSB) in pBR322 plasmid DNA in the presence of heat or piperidine. DNA adducts formed by methyl methanesulfonate, cisplatin, and chromic chloride were compared with those formed by reaction of uranyl acetate and ascorbate. Uranyl ion in the presence of ascorbate produced U-DNA adducts that converted to SSB on heating. Piperidine, which acted on DNA methylated by methyl methanesulfonate to convert methyl-DNA adducts to SSB, served in the opposite fashion as U-DNA adducts by decreasing the level of SSB. The observation that piperidine also decreased the gel shift for metal-DNA adducts formed by monofunctional cisplatin and chromic chloride was interpreted to suggest that piperidine served to remove U-DNA adducts. Radical scavengers did not affect the formation of uranium-induced SSB, suggesting that SSB arose from the presence of U-DNA adducts and not from the presence of free radicals. A model is proposed to predict how U-DNA adducts may serve as initial lesions that convert to SSB or AP sites. The results suggest that DU can act as a chemical genotoxin that does not require radiation for its mode of action. Characterizing the DNA lesions formed by DU is necessary to assess the relative importance of different DNA lesions in the formation of DU-induced mutations. Understanding the mechanisms of formation of DU-induced mutations may contribute to identification of biomarkers of DU exposure in humans.","Analysis of heat-labile sites generated by reactions of depleted uranium and ascorbate in plasmid DNA Abs: The goal of this study was to characterize how depleted uranium (DU) causes DNA damage. Procedures were developed to assess the ability of organic and inorganic DNA adducts to convert to single-strand breaks (SSB) in pBR322 plasmid DNA in the presence of heat or piperidine. DNA adducts formed by methyl methanesulfonate, cisplatin, and chromic chloride were compared with those formed by reaction of uranyl acetate and ascorbate. Uranyl ion in the presence of ascorbate produced U-DNA adducts that converted to SSB on heating. Piperidine, which acted on DNA methylated by methyl methanesulfonate to convert methyl-DNA adducts to SSB, served in the opposite fashion as U-DNA adducts by decreasing the level of SSB. The observation that piperidine also decreased the gel shift for metal-DNA adducts formed by monofunctional cisplatin and chromic chloride was interpreted to suggest that piperidine served to remove U-DNA adducts. Radical scavengers did not affect the formation of uranium-induced SSB, suggesting that SSB arose from the presence of U-DNA adducts and not from the presence of free radicals. A model is proposed to predict how U-DNA adducts may serve as initial lesions that convert to SSB or AP sites. The results suggest that DU can act as a chemical genotoxin that does not require radiation for its mode of action. Characterizing the DNA lesions formed by DU is necessary to assess the relative importance of different DNA lesions in the formation of DU-induced mutations. Understanding the mechanisms of formation of DU-induced mutations may contribute to identification of biomarkers of DU exposure in humans."
2225281,Ibrahim et al. 2013,Detoxification of Hexavalent Chromate by Amphibacillus sp KSUCr3 Cells Immobilised in Silica-coated Magnetic Alginate Beads,,Detoxification of Hexavalent Chromate by Amphibacillus sp KSUCr3 Cells Immobilised in Silica-coated Magnetic Alginate Beads Abs: 
2225280,Song et al. 2014,Investigations on photoelectrocatalytic reduction of Cr(VI) over titanium dioxide anode and metal cathode,,Investigations on photoelectrocatalytic reduction of Cr(VI) over titanium dioxide anode and metal cathode Abs: 
2225279,Fernandes et al. 2013,Novel Composite Material Polyoxovanadate@MIL-101(Cr): A Highly Efficient Electrocatalyst for Ascorbic Acid Oxidation,,Novel Composite Material Polyoxovanadate@MIL-101(Cr): A Highly Efficient Electrocatalyst for Ascorbic Acid Oxidation Abs: 
2225278,Sfaksi et al. 2014,Removal of Cr(VI) from water by cork waste,,Removal of Cr(VI) from water by cork waste Abs: 
2225277,Mccarthy et al. 2014,Fabrication of highly transparent and conducting PEDOT:PSS films using a formic acid treatment,,Fabrication of highly transparent and conducting PEDOT:PSS films using a formic acid treatment Abs: 
2225275,Bonnand et al. 2013,The chromium isotopic composition of seawater and marine carbonates,,The chromium isotopic composition of seawater and marine carbonates Abs: 
2225274,Boldyrev et al. 2013,Thin film nonstoichiometric chromium oxide-based cathode material for rechargeable and primary lithium batteries,,Thin film nonstoichiometric chromium oxide-based cathode material for rechargeable and primary lithium batteries Abs: 
2225273,Bohrn et al. 2013,A critical comparison of cell-based sensor systems for the detection of Cr(VI) in aquatic environment,,A critical comparison of cell-based sensor systems for the detection of Cr(VI) in aquatic environment Abs: 
2225272,Bianchini et al. 2013,OPHIOLITE INHERITANCE IN THE PO PLAIN SEDIMENTS: INSIGHTS ON HEAVY METALS DISTRIBUTION AND RISK ASSESSMENT,,OPHIOLITE INHERITANCE IN THE PO PLAIN SEDIMENTS: INSIGHTS ON HEAVY METALS DISTRIBUTION AND RISK ASSESSMENT Abs: 
2225271,Bhaumik et al. 2013,Chromium(VI) removal from water using fixed bed column of polypyrrole/Fe3O4 nanocomposite,,Chromium(VI) removal from water using fixed bed column of polypyrrole/Fe3O4 nanocomposite Abs: 
2225270,Bhattacharya et al. 2014,Computational and experimental study of chromium (VI) removal in direct contact membrane distillation,,Computational and experimental study of chromium (VI) removal in direct contact membrane distillation Abs: 
2225269,Berkmanns 2013,NO-Doped Shielding Gases Benefit Stainless Steel Welding,,NO-Doped Shielding Gases Benefit Stainless Steel Welding Abs: 
2225268,Benvenho et al. 2013,Study of poly(3-hexylthiophene)/cross-linked poly(vinyl alcohol) as semiconductor/insulator for application in low voltage organic field effect transistors,,Study of poly(3-hexylthiophene)/cross-linked poly(vinyl alcohol) as semiconductor/insulator for application in low voltage organic field effect transistors Abs: 
2225267,Ben Hmamou et al. 2013,Studies on the inhibitive effect of potassium ferrocyanide on the corrosion of steel in phosphoric acid,,Studies on the inhibitive effect of potassium ferrocyanide on the corrosion of steel in phosphoric acid Abs: 
2225266,Bebga et al. 2013,"Crystal structure of potassium trans-diaquabis[oxalato-kappa O-2,O] chromate(III) urea disolvate, K[CrC2O4)(2)H2O)(2)]center dot 2CO(NH2)(2), C6H12CrKN4O12",,"Crystal structure of potassium trans-diaquabis[oxalato-kappa O-2,O] chromate(III) urea disolvate, K[CrC2O4)(2)H2O)(2)]center dot 2CO(NH2)(2), C6H12CrKN4O12 Abs: "
2225264,Bayrak et al. 2013,"Kinetics and Thermodynamics of Cr(VI), Cu(II), and Ni(II) Adsorption on Activated Carbon Prepared from Rice Hulls",,"Kinetics and Thermodynamics of Cr(VI), Cu(II), and Ni(II) Adsorption on Activated Carbon Prepared from Rice Hulls Abs: "
2225263,Basu et al. 2013,Combination of Best Promoter and Micellar Catalyst for Chromic Acid Oxidation of D-Mannitol to Mannose in Aqueous Media,,Combination of Best Promoter and Micellar Catalyst for Chromic Acid Oxidation of D-Mannitol to Mannose in Aqueous Media Abs: 
2225262,Baralkiewicz et al. 2013,Speciation analysis of chromium in drinking water samples by ion-pair reversed-phase HPLC-ICP-MS: validation of the analytical method and evaluation of the uncertainty budget,,Speciation analysis of chromium in drinking water samples by ion-pair reversed-phase HPLC-ICP-MS: validation of the analytical method and evaluation of the uncertainty budget Abs: 
2225261,Bampaiti et al. 2013,Investigation of the Cr(VI) removal from aqueous solutions by stabilized iron-nanoparticles using Cr-51-tracer,,Investigation of the Cr(VI) removal from aqueous solutions by stabilized iron-nanoparticles using Cr-51-tracer Abs: 
2225260,Ballardin and  Iannone 2013,A STUDY ON THE RELIABILITY OF UNI EN ISO 17075 METHOD FOR THE DETERMINATION OF THE CR(VI) CONTENT IN LEATHER,,A STUDY ON THE RELIABILITY OF UNI EN ISO 17075 METHOD FOR THE DETERMINATION OF THE CR(VI) CONTENT IN LEATHER Abs: 
2225259,Balan et al. 2013,CHROMIUM (VI) REMOVAL FROM AQUEOUS SOLUTIONS BY PUROLITE BASE ANION-EXCHANGE RESINS WITH GEL STRUCTURE,,CHROMIUM (VI) REMOVAL FROM AQUEOUS SOLUTIONS BY PUROLITE BASE ANION-EXCHANGE RESINS WITH GEL STRUCTURE Abs: 
2225258,Baig et al. 2013,Removal of hexavalent chromium by limonite in aqueous solutions,,Removal of hexavalent chromium by limonite in aqueous solutions Abs: 
2225257,Bahafid et al. 2013,Bioaugmentation of chromium-polluted soil microcosms with Candida tropicalis diminishes phytoavailable chromium,,Bioaugmentation of chromium-polluted soil microcosms with Candida tropicalis diminishes phytoavailable chromium Abs: 
2225256,Babu et al. 2013,Biosorption of Chromium from Synthetic Aqueous Solution using Codium Tomentosum,,Biosorption of Chromium from Synthetic Aqueous Solution using Codium Tomentosum Abs: 
2225255,Babu et al. 2013,Biosorption of Chromium(VI) and Lead(II): Role of Spirulina platensis in the Treatment of Industrial Effluent,,Biosorption of Chromium(VI) and Lead(II): Role of Spirulina platensis in the Treatment of Industrial Effluent Abs: 
2225254,Asgari et al. 2013,"Cr (VI) adsorption from aqueous solution using a surfactant-modified Iranian zeolite: characterization, optimization, and kinetic approach",,"Cr (VI) adsorption from aqueous solution using a surfactant-modified Iranian zeolite: characterization, optimization, and kinetic approach Abs: "
2225253,Araujo et al. 2013,Application of termite nest for adsorption of Cr(VI),,Application of termite nest for adsorption of Cr(VI) Abs: 
2225252,Anirudhan et al. 2013,Adsorption of chromium(VI) from aqueous solutions by glycidylmethacrylate-grafted-densified cellulose with quaternary ammonium groups,,Adsorption of chromium(VI) from aqueous solutions by glycidylmethacrylate-grafted-densified cellulose with quaternary ammonium groups Abs: 
2225251,Anicai et al. 2013,Polypyrrole Films Doped with Phosphomolybdate Anions on Al Surfaces - Formation and Corrosion Protection Characterisation,,Polypyrrole Films Doped with Phosphomolybdate Anions on Al Surfaces - Formation and Corrosion Protection Characterisation Abs: 
2225250,Amirbahman et al. 2013,Kinetics of Homogeneous and Surface-Catalyzed Mercury(II) Reduction by Iron(II),,Kinetics of Homogeneous and Surface-Catalyzed Mercury(II) Reduction by Iron(II) Abs: 
2225249,Amenu et al. 2013,Water for human and livestock consumption in rural settings of Ethiopia: assessments of quality and health aspects,,Water for human and livestock consumption in rural settings of Ethiopia: assessments of quality and health aspects Abs: 
2225248,Alyuruk et al. 2013,A video tracking based improvement of acute toxicity test on Artemia salina,,A video tracking based improvement of acute toxicity test on Artemia salina Abs: 
2225247,Altaf and  Jaganyi 2013,Oxidation of Methionine by Colloidal MnO2 in Aqueous and Micellar Media: A Kinetic Study,,Oxidation of Methionine by Colloidal MnO2 in Aqueous and Micellar Media: A Kinetic Study Abs: 
2225246,Alimohammadi et al. 2013,Removal of cadmium from drilling fluid using nano-adsorbent,,Removal of cadmium from drilling fluid using nano-adsorbent Abs: 
2225245,Alfeld and  Broekaert 2013,Mobile depth profiling and sub-surface imaging techniques for historical paintings - A review,,Mobile depth profiling and sub-surface imaging techniques for historical paintings - A review Abs: 
2225244,Alanis et al. 2013,Photocatalytically enhanced Cr(VI) removal by mixed oxides derived from MeAl (Me:Mg and/or Zn) layered double hydroxides,"This work aims to present a study of the adsorption and photocatalytic reduction of Cr(VI) by ZnAl, MgZnAl and MgAl mixed oxides derived from layered double hydroxides (LDHs). The effect of variables like Zn content and pH (3 and 6.5) on Cr(VI) removal efficiency is presented. The catalysts were characterized by X-ray diffraction (XRD) and infrared spectroscopy (FTIR). The reaction progress was verified by UV/vis spectrophotometry with a colorimetric method. A maximum of 99.5% Cr(VI) was photocatalytically removed and this process was approximately two times faster than adsorption. In addition, it was found that the use of these materials does not imply the addition of further chemicals to regulate pH since the free basic pH of the catalyst-contaminant suspension positively affects both adsorption and photo-reduction kinetics.","Photocatalytically enhanced Cr(VI) removal by mixed oxides derived from MeAl (Me:Mg and/or Zn) layered double hydroxides Abs: This work aims to present a study of the adsorption and photocatalytic reduction of Cr(VI) by ZnAl, MgZnAl and MgAl mixed oxides derived from layered double hydroxides (LDHs). The effect of variables like Zn content and pH (3 and 6.5) on Cr(VI) removal efficiency is presented. The catalysts were characterized by X-ray diffraction (XRD) and infrared spectroscopy (FTIR). The reaction progress was verified by UV/vis spectrophotometry with a colorimetric method. A maximum of 99.5% Cr(VI) was photocatalytically removed and this process was approximately two times faster than adsorption. In addition, it was found that the use of these materials does not imply the addition of further chemicals to regulate pH since the free basic pH of the catalyst-contaminant suspension positively affects both adsorption and photo-reduction kinetics."
2225243,Alam and  Ahmad 2013,Multi-metal biosorption and bioaccumulation by Exiguobacterium sp ZM-2,,Multi-metal biosorption and bioaccumulation by Exiguobacterium sp ZM-2 Abs: 
2225242,Akyuz et al. 2013,Selective Determination of Cr(VI) by FAAS After Solid Phase Extraction on Bis(3-aminopropyl)amine-Bonded Silica Gel,,Selective Determination of Cr(VI) by FAAS After Solid Phase Extraction on Bis(3-aminopropyl)amine-Bonded Silica Gel Abs: 
2225241,Akceylan et al. 2013,Synthesis and properties of calix[4]arene polymers containing amide groups: Exploration of their extraction properties towards dichromate and nitrite anions,,Synthesis and properties of calix[4]arene polymers containing amide groups: Exploration of their extraction properties towards dichromate and nitrite anions Abs: 
2225240,Ahmad et al. 2013,Cr(VI) reduction in naturally rich growth medium and sugarcane bagasse by Acinetobacter haemolyticus,,Cr(VI) reduction in naturally rich growth medium and sugarcane bagasse by Acinetobacter haemolyticus Abs: 
2225239,Ahluwalia and  Goyal 2013,Microbial Waste Biomass for Removal of Chromium(VI) from Chrome Effluent,,Microbial Waste Biomass for Removal of Chromium(VI) from Chrome Effluent Abs: 
2225238,Aghebati-Maleki et al. 2014,Designing a Hydrogen Peroxide Biosensor Using Catalase and Modified Electrode with Magnesium Oxide Nanoparticles,,Designing a Hydrogen Peroxide Biosensor Using Catalase and Modified Electrode with Magnesium Oxide Nanoparticles Abs: 
2225237,Adegoke et al. 2014,Adsorption of Cr (VI) on synthetic hematite (alpha-Fe2O3) nanoparticles of different morphologies,,Adsorption of Cr (VI) on synthetic hematite (alpha-Fe2O3) nanoparticles of different morphologies Abs: 
2225236,Achal et al. 2013,Remediation of Cr(VI) from chromium slag by biocementation,,Remediation of Cr(VI) from chromium slag by biocementation Abs: 
2225235,Abdullah et al. 2013,Dissolution equilibrium of chromium oxide in a soda lime silicate melt exposed to oxidizing and reducing atmospheres,,Dissolution equilibrium of chromium oxide in a soda lime silicate melt exposed to oxidizing and reducing atmospheres Abs: 
2225184,Paulson et al. 2014,Cost and Performance Report: Innovative Welding Technologies Using Silicon Additives to Control Hazardous Air Pollutant (HAP) Emissions,,Cost and Performance Report: Innovative Welding Technologies Using Silicon Additives to Control Hazardous Air Pollutant (HAP) Emissions Abs: 
2225183,Nickerson and  Matzdorf 2013,Non-Chromate Aluminum Pretreatments,,Non-Chromate Aluminum Pretreatments Abs: 
2225101,Zhao and  Dong 2013,A microfluidic device for continuous sensing of systemic acute toxicants in drinking water,"A bioluminescent-cell-based microfluidic device for sensing toxicants in drinking water was designed and fabricated. The system employed Vibrio fischeri cells as broad-spectrum sensors to monitor potential systemic cell toxicants in water, such as heavy metal ions and phenol. Specifically, the chip was designed for continuous detection. The chip design included two counter-flow micromixers, a T-junction droplet generator and six spiral microchannels. The cell suspension and water sample were introduced into the micromixers and dispersed into droplets in the air flow. This guaranteed sufficient oxygen supply for the cell sensors. Copper (Cu2+), zinc (Zn2+), potassium dichromate and 3,5-dichlorophenol were selected as typical toxicants to validate the sensing system. Preliminary tests verified that the system was an effective screening tool for acute toxicants although it could not recognize or quantify specific toxicants. A distinct non-linear relationship was observed between the zinc ion concentration and the Relative Luminescence Units (RLU) obtained during testing. Thus, the concentration of simple toxic chemicals in water can be roughly estimated by this system. The proposed device shows great promise for an early warning system for water safety.","A microfluidic device for continuous sensing of systemic acute toxicants in drinking water Abs: A bioluminescent-cell-based microfluidic device for sensing toxicants in drinking water was designed and fabricated. The system employed Vibrio fischeri cells as broad-spectrum sensors to monitor potential systemic cell toxicants in water, such as heavy metal ions and phenol. Specifically, the chip was designed for continuous detection. The chip design included two counter-flow micromixers, a T-junction droplet generator and six spiral microchannels. The cell suspension and water sample were introduced into the micromixers and dispersed into droplets in the air flow. This guaranteed sufficient oxygen supply for the cell sensors. Copper (Cu2+), zinc (Zn2+), potassium dichromate and 3,5-dichlorophenol were selected as typical toxicants to validate the sensing system. Preliminary tests verified that the system was an effective screening tool for acute toxicants although it could not recognize or quantify specific toxicants. A distinct non-linear relationship was observed between the zinc ion concentration and the Relative Luminescence Units (RLU) obtained during testing. Thus, the concentration of simple toxic chemicals in water can be roughly estimated by this system. The proposed device shows great promise for an early warning system for water safety."
2225100,Zhang et al. 2013,[Research on the application of in-situ biological stabilization solidification technology in chromium contaminated site management],"In-situ biological stabilization solidification (SS) technology is an effective ground water risk control method for chromium contaminated sites. Through on-site engineering test, this paper has preliminarily validated the remediation effect of in-situ SS method on a southern chromium contaminated site. The engineering test site has an area of approximately 600 m2, and is located at the upstream of the contaminated area. Due to the severe contamination of chromium, the total chromium concentration reached up to 11,850 mg x kg(-1), while the hexavalent chromium concentration reached up to 349 mg x kg(-1), and the most severely contaminated soil had a depth of -0.5 - -2 m. Variations in hexavalent chromium and total chromium concentration in groundwater were observed through the injection of reducing agents and microbial regulators into the injection wells in the test site, and through the monitoring analysis at different time and different depth under the action of the injection agents. Results of the engineering test showed that the on-site SS technology significantly changed the chromium speciation in soil and then reduced the migration of chromium, thus the groundwater risk was reduced. The injected agents had a good effect of hexavalent chromium remediation in groundwater within the effective range of the injection wells, and the SS rate of hexavalent chromium into trivalent chromium reached 94%-99.9%, the SS rate of total chromium fixation reached 83.9%-99.8%. The test results are of significant reference value for the remediation of contaminated sites with features of shallow groundwater depth and soil mainly consisting of silty clay and sandy clay.","[Research on the application of in-situ biological stabilization solidification technology in chromium contaminated site management] Abs: In-situ biological stabilization solidification (SS) technology is an effective ground water risk control method for chromium contaminated sites. Through on-site engineering test, this paper has preliminarily validated the remediation effect of in-situ SS method on a southern chromium contaminated site. The engineering test site has an area of approximately 600 m2, and is located at the upstream of the contaminated area. Due to the severe contamination of chromium, the total chromium concentration reached up to 11,850 mg x kg(-1), while the hexavalent chromium concentration reached up to 349 mg x kg(-1), and the most severely contaminated soil had a depth of -0.5 - -2 m. Variations in hexavalent chromium and total chromium concentration in groundwater were observed through the injection of reducing agents and microbial regulators into the injection wells in the test site, and through the monitoring analysis at different time and different depth under the action of the injection agents. Results of the engineering test showed that the on-site SS technology significantly changed the chromium speciation in soil and then reduced the migration of chromium, thus the groundwater risk was reduced. The injected agents had a good effect of hexavalent chromium remediation in groundwater within the effective range of the injection wells, and the SS rate of hexavalent chromium into trivalent chromium reached 94%-99.9%, the SS rate of total chromium fixation reached 83.9%-99.8%. The test results are of significant reference value for the remediation of contaminated sites with features of shallow groundwater depth and soil mainly consisting of silty clay and sandy clay."
2225096,Stanislawska et al. 2013,Application of high performance liquid chromatography with inductively coupled plasma mass spectrometry (HPLC-ICP-MS) for determination of chromium compounds in the air at the workplace,"The toxicity and bioavailability of chromium species are highly dependable on the form or species, therefore determination of total chromium is insufficient for a complete toxicological evaluation and risk assessment. An analytical method for determination of soluble and insoluble Cr (III) and Cr (VI) compounds in welding fume at workplace air has been developed. The total chromium (Cr) was determined by using quadruple inductively coupled plasma mass spectrometry (ICP-MS) equipped with a dynamic reaction cell (DRC(®)). Soluble trivalent and hexavalent chromium compounds were determined by high performance liquid chromatography with inductively coupled plasma mass spectrometry (HPLC-ICP-MS). A high-speed, reversed-phase CR C8 column (PerkinElmer, Inc., Shelton, CT, USA) was used for the speciation of soluble Cr (III) and soluble Cr (VI). The separation was accomplished by interaction of the chromium species with the different components of the mobile phase. Cr (III) formed a complex with EDTA, i.e. retained on the column, while Cr (VI) existed in the solutions as dichromate. Alkaline extraction (2% KOH and 3% Na2CO3) and anion exchange column (PRP-X100, PEEK, Hamilton) were used for the separation of the total Cr (VI). The results of the determination of Cr (VI) were confirmed by the analysis of the certified reference material BCR CRM 545 (Cr (VI) in welding dust). The results obtained for the certified material (40.2±0.6 g kg(-1)) and the values recorded in the examined samples (40.7±0.6 g kg(-1)) were highly consistent. This analytical method was applied for the determination of chromium in the samples in the workplace air collected onto glass (Whatman, Ø 37 mm) and membrane filters (Sartorius, 0.8 ?m, Ø 37 mm). High performance liquid chromatography with inductively coupled plasma mass spectrometry is a remarkably powerful and versatile technique for determination of chromium species in welding fume at workplace air.","Application of high performance liquid chromatography with inductively coupled plasma mass spectrometry (HPLC-ICP-MS) for determination of chromium compounds in the air at the workplace Abs: The toxicity and bioavailability of chromium species are highly dependable on the form or species, therefore determination of total chromium is insufficient for a complete toxicological evaluation and risk assessment. An analytical method for determination of soluble and insoluble Cr (III) and Cr (VI) compounds in welding fume at workplace air has been developed. The total chromium (Cr) was determined by using quadruple inductively coupled plasma mass spectrometry (ICP-MS) equipped with a dynamic reaction cell (DRC(®)). Soluble trivalent and hexavalent chromium compounds were determined by high performance liquid chromatography with inductively coupled plasma mass spectrometry (HPLC-ICP-MS). A high-speed, reversed-phase CR C8 column (PerkinElmer, Inc., Shelton, CT, USA) was used for the speciation of soluble Cr (III) and soluble Cr (VI). The separation was accomplished by interaction of the chromium species with the different components of the mobile phase. Cr (III) formed a complex with EDTA, i.e. retained on the column, while Cr (VI) existed in the solutions as dichromate. Alkaline extraction (2% KOH and 3% Na2CO3) and anion exchange column (PRP-X100, PEEK, Hamilton) were used for the separation of the total Cr (VI). The results of the determination of Cr (VI) were confirmed by the analysis of the certified reference material BCR CRM 545 (Cr (VI) in welding dust). The results obtained for the certified material (40.2±0.6 g kg(-1)) and the values recorded in the examined samples (40.7±0.6 g kg(-1)) were highly consistent. This analytical method was applied for the determination of chromium in the samples in the workplace air collected onto glass (Whatman, Ø 37 mm) and membrane filters (Sartorius, 0.8 ?m, Ø 37 mm). High performance liquid chromatography with inductively coupled plasma mass spectrometry is a remarkably powerful and versatile technique for determination of chromium species in welding fume at workplace air."
2225095,Knight et al. 2013,Selective chromium(VI) ligands identified using combinatorial peptoid libraries,"Hexavalent chromium [Cr(VI)] is a worldwide water contaminant that is currently without cost-effective and efficient remediation strategies. This is in part due to a lack of ligands that can bind it amid an excess of innocuous ions in aqueous solution. We present herein the design and application of a peptoid-based library of ligand candidates for toxic metal ions. A selective screening process was used to identify members of the library that can bind to Cr(VI) species at neutral pH and in the presence of a large excess of spectator ions. There were 11 sequences identified, and their affinities were compared using titrations monitored with UV-vis spectroscopy. To identify the interactions involved in coordination and specificity, we evaluated the effects of sequence substitutions and backbone variation in the highest affinity structure. Additional characterization of the complex formed between this sequence and Cr(VI) was performed using NMR spectroscopy. To evaluate the ability of the developed sequences to remediate contaminated solutions, the structures were synthesized on a solid-phase resin and incubated with environmental water samples that contained simulated levels of chromium contamination. The synthetic structures demonstrated the ability to reduce the amount of toxic chromium to levels within the range of the EPA contamination guidelines. In addition to providing some of the first selective ligands for Cr(VI), these studies highlight the promise of peptoid sequences as easily prepared components of environmental remediation materials.","Selective chromium(VI) ligands identified using combinatorial peptoid libraries Abs: Hexavalent chromium [Cr(VI)] is a worldwide water contaminant that is currently without cost-effective and efficient remediation strategies. This is in part due to a lack of ligands that can bind it amid an excess of innocuous ions in aqueous solution. We present herein the design and application of a peptoid-based library of ligand candidates for toxic metal ions. A selective screening process was used to identify members of the library that can bind to Cr(VI) species at neutral pH and in the presence of a large excess of spectator ions. There were 11 sequences identified, and their affinities were compared using titrations monitored with UV-vis spectroscopy. To identify the interactions involved in coordination and specificity, we evaluated the effects of sequence substitutions and backbone variation in the highest affinity structure. Additional characterization of the complex formed between this sequence and Cr(VI) was performed using NMR spectroscopy. To evaluate the ability of the developed sequences to remediate contaminated solutions, the structures were synthesized on a solid-phase resin and incubated with environmental water samples that contained simulated levels of chromium contamination. The synthetic structures demonstrated the ability to reduce the amount of toxic chromium to levels within the range of the EPA contamination guidelines. In addition to providing some of the first selective ligands for Cr(VI), these studies highlight the promise of peptoid sequences as easily prepared components of environmental remediation materials."
2225094,Heck et al. 2013,An exploratory study of ambient air toxics exposure in pregnancy and the risk of neuroblastoma in offspring,"Little is known about the etiology of neuroblastoma, the most common cancer in infancy. In this study, we examined maternal exposure to ambient air toxics in pregnancy in relation to neuroblastoma in the child. We ascertained all cases of neuroblastoma listed in the California Cancer Registry 1990-2007 that could be linked to a California birth certificate, and controls were selected at random from California birth records. Average air toxics exposures during pregnancy were determined based upon measures from community-based air pollution monitors. The study included 75 cases and 14,602 controls who lived with 5 km of an air pollution monitor, and we additionally examined results for those living within a smaller radius around the monitor (2.5 km). Logistic regression was used to determine the risk of neuroblastoma with one interquartile range increase in air toxic exposure. Neuroblastoma risk was increased with higher maternal exposure to carbon tetrachloride (OR=2.65, 95%CI 1.07, 6.53) and polycyclic aromatic hydrocarbons (OR=1.39, 95%CI 1.05, 1.84), particularly indeno(1,2,3-cd)pyrene and dibenz(a,h)anthracene. Hexavalent chromium was associated with neuroblastoma at the 5 km distance (OR=1.32, 95%CI 1.00, 1.74) but not at the 2.5 km distance. This is one of the first studies to report associations between neuroblastoma and these air toxics.","An exploratory study of ambient air toxics exposure in pregnancy and the risk of neuroblastoma in offspring Abs: Little is known about the etiology of neuroblastoma, the most common cancer in infancy. In this study, we examined maternal exposure to ambient air toxics in pregnancy in relation to neuroblastoma in the child. We ascertained all cases of neuroblastoma listed in the California Cancer Registry 1990-2007 that could be linked to a California birth certificate, and controls were selected at random from California birth records. Average air toxics exposures during pregnancy were determined based upon measures from community-based air pollution monitors. The study included 75 cases and 14,602 controls who lived with 5 km of an air pollution monitor, and we additionally examined results for those living within a smaller radius around the monitor (2.5 km). Logistic regression was used to determine the risk of neuroblastoma with one interquartile range increase in air toxic exposure. Neuroblastoma risk was increased with higher maternal exposure to carbon tetrachloride (OR=2.65, 95%CI 1.07, 6.53) and polycyclic aromatic hydrocarbons (OR=1.39, 95%CI 1.05, 1.84), particularly indeno(1,2,3-cd)pyrene and dibenz(a,h)anthracene. Hexavalent chromium was associated with neuroblastoma at the 5 km distance (OR=1.32, 95%CI 1.00, 1.74) but not at the 2.5 km distance. This is one of the first studies to report associations between neuroblastoma and these air toxics."
2225093,Pereira et al. 2013,Influence of pH on the survival of Dictyosphaerium chlorelloides populations living in aquatic environments highly contaminated with chromium,"The accommodation of photosynthetic organisms to adverse conditions, such as pH changes in the aquatic environment, and their response to aquatic pollutants is essential to develop future biosensors. The present study reports the ability of both Cr(VI)-sensitive and tolerant Dyctiosphaerium chlorelloides strains to live in aqueous solutions highly contaminated with hexavalent chromium under varying ranges of pH, by the determination of chromium toxic effects on these strains. Studies of cell growth, photosynthetic quantum yield and gross photosynthesis rate show that both D. chlorelloides strains are able to survive in alkaline and moderately acidified (pH 4.25) aquatic environments. Below this pH value cell populations from both strains exposed for short periods of time to Cr(VI) showed alterations in the three parameters studied. There were no significant differences comparing the response of both strains at pH change in the culture medium. However, Cr(VI)-tolerant strain exhibits a better fit to maintain cell growth than Cr(VI)-sensitive strain when both were subjected to pH 4.25 in the culture medium. The absence of significant differences in photosynthetic activity results for both strains suggests that the lower sensitivity exhibited by Cr(VI)-tolerant strain would be due to cellular morphological changes rather than changes in cellular activity.","Influence of pH on the survival of Dictyosphaerium chlorelloides populations living in aquatic environments highly contaminated with chromium Abs: The accommodation of photosynthetic organisms to adverse conditions, such as pH changes in the aquatic environment, and their response to aquatic pollutants is essential to develop future biosensors. The present study reports the ability of both Cr(VI)-sensitive and tolerant Dyctiosphaerium chlorelloides strains to live in aqueous solutions highly contaminated with hexavalent chromium under varying ranges of pH, by the determination of chromium toxic effects on these strains. Studies of cell growth, photosynthetic quantum yield and gross photosynthesis rate show that both D. chlorelloides strains are able to survive in alkaline and moderately acidified (pH 4.25) aquatic environments. Below this pH value cell populations from both strains exposed for short periods of time to Cr(VI) showed alterations in the three parameters studied. There were no significant differences comparing the response of both strains at pH change in the culture medium. However, Cr(VI)-tolerant strain exhibits a better fit to maintain cell growth than Cr(VI)-sensitive strain when both were subjected to pH 4.25 in the culture medium. The absence of significant differences in photosynthetic activity results for both strains suggests that the lower sensitivity exhibited by Cr(VI)-tolerant strain would be due to cellular morphological changes rather than changes in cellular activity."
2225092,Zeidler-Erdely et al. 2013,Lung tumor promotion by chromium-containing welding particulate matter in a mouse model,"<strong>BACKGROUND: </strong>Epidemiology suggests that occupational exposure to welding particulate matter (PM) may increase lung cancer risk. However, animal studies are lacking to conclusively link welding with an increased risk. PM derived from stainless steel (SS) welding contains carcinogenic metals such as hexavalent chromium and nickel. We hypothesized that welding PM may act as a tumor promoter and increase lung tumor multiplicity in vivo. Therefore, the capacity of chromium-containing gas metal arc (GMA)-SS welding PM to promote lung tumors was evaluated using a two-stage (initiation-promotion) model in lung tumor susceptible A/J mice.<br /><br /><strong>METHODS: </strong>Male mice (n = 28-30/group) were treated either with the initiator 3-methylcholanthrene (MCA;10 ?g/g; IP) or vehicle (corn oil) followed by 5 weekly pharyngeal aspirations of GMA-SS (340 or 680 ?g/exposure) or PBS. Lung tumors were enumerated at 30 weeks post-initiation.<br /><br /><strong>RESULTS: </strong>MCA initiation followed by GMA-SS welding PM exposure promoted tumor multiplicity in both the low (12.1 ± 1.5 tumors/mouse) and high (14.0 ± 1.8 tumors/mouse) exposure groups significantly above MCA/sham (4.77 ± 0.7 tumors/mouse; p = 0.0001). Multiplicity was also highly significant (p < 0.004) across all individual lung regions of GMA-SS-exposed mice. No exposure effects were found in the corn oil groups at 30 weeks. Histopathology confirmed the gross findings and revealed increased inflammation and a greater number of malignant lesions in the MCA/welding PM-exposed groups.<br /><br /><strong>CONCLUSIONS: </strong>GMA-SS welding PM acts as a lung tumor promoter in vivo. Thus, this study provides animal evidence to support the epidemiological data that show welders have an increased lung cancer risk.","Lung tumor promotion by chromium-containing welding particulate matter in a mouse model Abs: <strong>BACKGROUND: </strong>Epidemiology suggests that occupational exposure to welding particulate matter (PM) may increase lung cancer risk. However, animal studies are lacking to conclusively link welding with an increased risk. PM derived from stainless steel (SS) welding contains carcinogenic metals such as hexavalent chromium and nickel. We hypothesized that welding PM may act as a tumor promoter and increase lung tumor multiplicity in vivo. Therefore, the capacity of chromium-containing gas metal arc (GMA)-SS welding PM to promote lung tumors was evaluated using a two-stage (initiation-promotion) model in lung tumor susceptible A/J mice.<br /><br /><strong>METHODS: </strong>Male mice (n = 28-30/group) were treated either with the initiator 3-methylcholanthrene (MCA;10 ?g/g; IP) or vehicle (corn oil) followed by 5 weekly pharyngeal aspirations of GMA-SS (340 or 680 ?g/exposure) or PBS. Lung tumors were enumerated at 30 weeks post-initiation.<br /><br /><strong>RESULTS: </strong>MCA initiation followed by GMA-SS welding PM exposure promoted tumor multiplicity in both the low (12.1 ± 1.5 tumors/mouse) and high (14.0 ± 1.8 tumors/mouse) exposure groups significantly above MCA/sham (4.77 ± 0.7 tumors/mouse; p = 0.0001). Multiplicity was also highly significant (p < 0.004) across all individual lung regions of GMA-SS-exposed mice. No exposure effects were found in the corn oil groups at 30 weeks. Histopathology confirmed the gross findings and revealed increased inflammation and a greater number of malignant lesions in the MCA/welding PM-exposed groups.<br /><br /><strong>CONCLUSIONS: </strong>GMA-SS welding PM acts as a lung tumor promoter in vivo. Thus, this study provides animal evidence to support the epidemiological data that show welders have an increased lung cancer risk."
2225091,Manríquez et al. 2013,"Ecotoxicological studies with newly hatched larvae of Concholepas concholepas (Mollusca, Gastropoda): bioassay with secondary-treated kraft pulp mill effluents","The Chilean abalone or &quot;loco&quot; (Concholepas concholepas, Bruguière 1789) represent the most economically important marine recourse exploited from inner inshore Management and Exploitation Areas for Benthic Resources along the Chilean coast. In this study, newly-hatched larvae of C. concholepas were investigated as a potential model species for marine ecotoxicological studies. The study developed a behavioral standard protocol for assessing the impact that kraft pulp mill effluents after secondary treatment have on C. concholepas larvae. Under controlled laboratory conditions, newly-hatched larvae were exposed to a series of different concentrations of kraft pulp mill effluents with secondary treatment (Pinus spp. and Eucalyptus spp.), potassium dichromate as standard reference toxicant and effluent-free control conditions. Regardless of the type of effluent the results indicated that diluted kraft pulp effluent with secondary treatment had reduced effect on larval survival. Low larval survivals were only recorded when they were exposed to high concentrations of the reference toxicant. This suggests that C. concholepas larval bioassay is a simple method for monitoring the effects of kraft pulp mill effluents with secondary treatment discharged into the sea. The results indicated that dilution of ca. 1% of the effluent with an elemental chlorine free (ECF) secondary treatment is appropriate for achieving low larval mortalities, such as those obtained under control conditions with filtered seawater, and to minimize their impact on early ontogenetic stages of marine invertebrates such as newly-hatched larvae of C. concholepas. The methodological aspects of toxicological testing and behavioral responses described here with newly-hatched larvae of C. concholepas can be used to evaluate in the future the potential effects of other stressful conditions as other pollutants or changes in seawater pH associated with ocean acidification.","Ecotoxicological studies with newly hatched larvae of Concholepas concholepas (Mollusca, Gastropoda): bioassay with secondary-treated kraft pulp mill effluents Abs: The Chilean abalone or &quot;loco&quot; (Concholepas concholepas, Bruguière 1789) represent the most economically important marine recourse exploited from inner inshore Management and Exploitation Areas for Benthic Resources along the Chilean coast. In this study, newly-hatched larvae of C. concholepas were investigated as a potential model species for marine ecotoxicological studies. The study developed a behavioral standard protocol for assessing the impact that kraft pulp mill effluents after secondary treatment have on C. concholepas larvae. Under controlled laboratory conditions, newly-hatched larvae were exposed to a series of different concentrations of kraft pulp mill effluents with secondary treatment (Pinus spp. and Eucalyptus spp.), potassium dichromate as standard reference toxicant and effluent-free control conditions. Regardless of the type of effluent the results indicated that diluted kraft pulp effluent with secondary treatment had reduced effect on larval survival. Low larval survivals were only recorded when they were exposed to high concentrations of the reference toxicant. This suggests that C. concholepas larval bioassay is a simple method for monitoring the effects of kraft pulp mill effluents with secondary treatment discharged into the sea. The results indicated that dilution of ca. 1% of the effluent with an elemental chlorine free (ECF) secondary treatment is appropriate for achieving low larval mortalities, such as those obtained under control conditions with filtered seawater, and to minimize their impact on early ontogenetic stages of marine invertebrates such as newly-hatched larvae of C. concholepas. The methodological aspects of toxicological testing and behavioral responses described here with newly-hatched larvae of C. concholepas can be used to evaluate in the future the potential effects of other stressful conditions as other pollutants or changes in seawater pH associated with ocean acidification."
2225090,Morse et al. 2013,Chromium(VI) causes interstrand DNA cross-linking in vitro but shows no hypersensitivity in cross-link repair-deficient human cells,"Hexavalent chromium is a human carcinogen activated primarily by direct reduction with cellular ascorbate and to a lesser extent, by glutathione. Cr(III), the final product of Cr(VI) reduction, forms six bonds allowing intermolecular cross-linking. In this work, we investigated the ability of Cr(VI) to cause interstrand DNA cross-links (ICLs) whose formation mechanisms and presence in human cells are currently uncertain. We found that in vitro reduction of Cr(VI) with glutathione showed a sublinear production of ICLs, the yield of which was less than 1% of total Cr-DNA adducts at the optimal conditions. Formation of ICLs in fast ascorbate-Cr(VI) reactions occurred during a short reduction interval and displayed a linear dose dependence with the average yield of 1.3% of total adducts. In vitro production of ICLs was strongly suppressed by increasing buffer molarity, indicating inhibitory effects of ligand-Cr(III) binding on the formation of cross-linking species. The presence of ICLs in human cells was assessed from the impact of ICL repair deficiencies on Cr(VI) responses. We found that ascorbate-restored FANCD2-null and isogenic FANCD2-complemented cells showed similar cell cycle inhibition and toxicity by Cr(VI). XPA-null cells are defective in the repair of Cr-DNA monoadducts, but stable knockdowns of ERCC1 or XPF in these cells with extended time for the completion of cross-linking reactions did not produce any sensitization to Cr(VI). Our results together with chemical and steric considerations of Cr(III) reactivity suggest that ICL generation by chromate is probably an in vitro phenomenon occurring at conditions permitting the formation of Cr(III) oligomers.","Chromium(VI) causes interstrand DNA cross-linking in vitro but shows no hypersensitivity in cross-link repair-deficient human cells Abs: Hexavalent chromium is a human carcinogen activated primarily by direct reduction with cellular ascorbate and to a lesser extent, by glutathione. Cr(III), the final product of Cr(VI) reduction, forms six bonds allowing intermolecular cross-linking. In this work, we investigated the ability of Cr(VI) to cause interstrand DNA cross-links (ICLs) whose formation mechanisms and presence in human cells are currently uncertain. We found that in vitro reduction of Cr(VI) with glutathione showed a sublinear production of ICLs, the yield of which was less than 1% of total Cr-DNA adducts at the optimal conditions. Formation of ICLs in fast ascorbate-Cr(VI) reactions occurred during a short reduction interval and displayed a linear dose dependence with the average yield of 1.3% of total adducts. In vitro production of ICLs was strongly suppressed by increasing buffer molarity, indicating inhibitory effects of ligand-Cr(III) binding on the formation of cross-linking species. The presence of ICLs in human cells was assessed from the impact of ICL repair deficiencies on Cr(VI) responses. We found that ascorbate-restored FANCD2-null and isogenic FANCD2-complemented cells showed similar cell cycle inhibition and toxicity by Cr(VI). XPA-null cells are defective in the repair of Cr-DNA monoadducts, but stable knockdowns of ERCC1 or XPF in these cells with extended time for the completion of cross-linking reactions did not produce any sensitization to Cr(VI). Our results together with chemical and steric considerations of Cr(III) reactivity suggest that ICL generation by chromate is probably an in vitro phenomenon occurring at conditions permitting the formation of Cr(III) oligomers."
2225089,Mydlík et al. 2013,Renal replacement therapy in acute poisonings--one center experience,"The authors described three groups of patients after acute poisonings. In the first group were 60 patients after carbon tetrachioride poisoning, the second group consisted of 81 patients after mushroom poisoning and 20 patients after ethylene glycol poisoning were in the third group. Besides two patients with rare poisonings after potassium dichromate and after paraquat poisoning were analysed. All groups of patients with the kidney damage were presented from the diagnostic, differential diagnostic, conservative, ntra- and extracorporeal elimination treatment point of view. In the group of patients suffering from acute carbon tetrachloride poisoning and with acute renal failure following therapy was used: conservative treatment, exchange blood transfusion--in 4 patients in hepatic coma, renal replacement therapy (peritoneal dialysis, haemodialysis, plasmapheresis). From the total number of 60 patients 58 survived and 2 patients died in liver coma. Survival of patients after mushroom poisoning depended on amount of oral use of mushroom (Amanita phalloides), on early admission in dialysis centre and on early beginning of renal replacement therapy within 24 hr after acute poisoning. Twenty four patients from 81 patients of this group died. Main clinical signs of ethylene glycol poisoning were various neurological symptoms (cramps, hemiparesis, coma), severe metabolic acidosis (pH = 7.06 +/- 0.14), leucocytosis (26.4 +/- 5.5x 10(9)/L) and the signs of acute toxic hepatitis and of acute renal failure. Calcium oxalic crystals in urine were present in 17 patients and leucocytosis was observed in every patient. In the first 4 patients we administered intravenously ethylalcohol as an antidotum and later in other patients we used ethylalcohol in dialysis solution. The concentration of ethylalcohol in dialysis solution was 100 mg%. Severe metabolic acidosis improved in 17 patients using bicarbonate haemodialysis and 3 patients died before the possibility to use bicarbonate haemodialysis. Eighty-four hours after acute potassium dichromate poisoning and 24 hours after exchange blood transfusion during haemodialysis a 41-year old man died in haemorhagic shock, which developed after the extensive chemical burns of mucous membrane of gastrointestinal tract caused by this poison. Our patient after paraquat poisoning was treated by repeated charcoal haemoperfusion and haemodialysis. Despite of that therapy the patient died in severe respiratory insufficiency.","Renal replacement therapy in acute poisonings--one center experience Abs: The authors described three groups of patients after acute poisonings. In the first group were 60 patients after carbon tetrachioride poisoning, the second group consisted of 81 patients after mushroom poisoning and 20 patients after ethylene glycol poisoning were in the third group. Besides two patients with rare poisonings after potassium dichromate and after paraquat poisoning were analysed. All groups of patients with the kidney damage were presented from the diagnostic, differential diagnostic, conservative, ntra- and extracorporeal elimination treatment point of view. In the group of patients suffering from acute carbon tetrachloride poisoning and with acute renal failure following therapy was used: conservative treatment, exchange blood transfusion--in 4 patients in hepatic coma, renal replacement therapy (peritoneal dialysis, haemodialysis, plasmapheresis). From the total number of 60 patients 58 survived and 2 patients died in liver coma. Survival of patients after mushroom poisoning depended on amount of oral use of mushroom (Amanita phalloides), on early admission in dialysis centre and on early beginning of renal replacement therapy within 24 hr after acute poisoning. Twenty four patients from 81 patients of this group died. Main clinical signs of ethylene glycol poisoning were various neurological symptoms (cramps, hemiparesis, coma), severe metabolic acidosis (pH = 7.06 +/- 0.14), leucocytosis (26.4 +/- 5.5x 10(9)/L) and the signs of acute toxic hepatitis and of acute renal failure. Calcium oxalic crystals in urine were present in 17 patients and leucocytosis was observed in every patient. In the first 4 patients we administered intravenously ethylalcohol as an antidotum and later in other patients we used ethylalcohol in dialysis solution. The concentration of ethylalcohol in dialysis solution was 100 mg%. Severe metabolic acidosis improved in 17 patients using bicarbonate haemodialysis and 3 patients died before the possibility to use bicarbonate haemodialysis. Eighty-four hours after acute potassium dichromate poisoning and 24 hours after exchange blood transfusion during haemodialysis a 41-year old man died in haemorhagic shock, which developed after the extensive chemical burns of mucous membrane of gastrointestinal tract caused by this poison. Our patient after paraquat poisoning was treated by repeated charcoal haemoperfusion and haemodialysis. Despite of that therapy the patient died in severe respiratory insufficiency."
2225088,Arévalo-Rangel et al. 2013,Hexavalent Chromate Reductase Activity in Cell Free Extracts of Penicillium sp,"A chromium-resistant fungus isolated from contaminated air with industrial vapors can be used for reducing toxic Cr(VI) to Cr(III). This study analyzes in vitro reduction of hexavalent chromium using cell free extract(s) of the fungus that was characterized based on optimal temperature, pH, use of electron donors, metal ions and initial Cr(VI) concentration in the reaction mixture. This showed the highest activity at 37°C and pH 7.0; there is an increase in Cr(VI) reductase activity with addition of NADH as an electron donor, and it was highly inhibited by Hg(2+), Ca(2+) and Mg(2+), and azide, EDTA, and KCN.","Hexavalent Chromate Reductase Activity in Cell Free Extracts of Penicillium sp Abs: A chromium-resistant fungus isolated from contaminated air with industrial vapors can be used for reducing toxic Cr(VI) to Cr(III). This study analyzes in vitro reduction of hexavalent chromium using cell free extract(s) of the fungus that was characterized based on optimal temperature, pH, use of electron donors, metal ions and initial Cr(VI) concentration in the reaction mixture. This showed the highest activity at 37°C and pH 7.0; there is an increase in Cr(VI) reductase activity with addition of NADH as an electron donor, and it was highly inhibited by Hg(2+), Ca(2+) and Mg(2+), and azide, EDTA, and KCN."
2225087,Ping et al. 2013,Cytotoxicity and genotoxicity assessment of Euphorbia hirta in MCF-7 cell line model using comet assay,"<strong>OBJECTIVE: </strong>To evaluate the cytotoxicity and genotoxicity activity of Euphorbia hirta (E. hirta) in MCF-7 cell line model using comet assay.<br /><br /><strong>METHODS: </strong>The cytotoxicity of E. hirta extract was investigated by employing brine shrimp lethality assay and the genotoxicity of E. hirta was assessed by using Comet assay.<br /><br /><strong>RESULTS: </strong>Both toxicity tests exhibited significant toxicity result. In the comet assay, the E. hirta extract exhibited genotoxicity effects against MCF-7 DNA in a time-dependent manner by increasing mean percentage of DNA damage. The extract of E. hirta showed significant toxicity against brine shrimp with an LC?? value of 620.382 µg/mL (24 h). Comparison with positive control potassium dichromate signifies that cytotoxicity exhibited by the methanol extract might have moderate activity.<br /><br /><strong>CONCLUSION: </strong>The present work confirmed the cytotoxicity and genotoxicity of E. hirta. However, the observed toxicity of E. hirta extracts needs to be confirmed in additional studies.","Cytotoxicity and genotoxicity assessment of Euphorbia hirta in MCF-7 cell line model using comet assay Abs: <strong>OBJECTIVE: </strong>To evaluate the cytotoxicity and genotoxicity activity of Euphorbia hirta (E. hirta) in MCF-7 cell line model using comet assay.<br /><br /><strong>METHODS: </strong>The cytotoxicity of E. hirta extract was investigated by employing brine shrimp lethality assay and the genotoxicity of E. hirta was assessed by using Comet assay.<br /><br /><strong>RESULTS: </strong>Both toxicity tests exhibited significant toxicity result. In the comet assay, the E. hirta extract exhibited genotoxicity effects against MCF-7 DNA in a time-dependent manner by increasing mean percentage of DNA damage. The extract of E. hirta showed significant toxicity against brine shrimp with an LC?? value of 620.382 µg/mL (24 h). Comparison with positive control potassium dichromate signifies that cytotoxicity exhibited by the methanol extract might have moderate activity.<br /><br /><strong>CONCLUSION: </strong>The present work confirmed the cytotoxicity and genotoxicity of E. hirta. However, the observed toxicity of E. hirta extracts needs to be confirmed in additional studies."
2225086,Y?ld?z et al. 2013,Protective role of hydrogen peroxide pretreatment on defense systems and BnMP1 gene expression in Cr(VI)-stressed canola seedlings,"To evaluate the ameliorating effects of hydrogen peroxide (H2O2, 200 ?M) on hexavalent chromium [Cr(VI)] toxicity in canola (Brassica napus L.), we focused on the plant growth, chlorophyll content, thiol contents, lipid peroxidation, antioxidant enzymes, and the expression of metallothionein protein (BnMP1) mRNA. Cr(VI) at 50 ?M significantly decreased the plant growth (fresh and dry weights). The decrease in growth was accompanied by increased lipid peroxidation and decreased chlorophyll content in leaves. Hydrogen peroxide pretreatment, however, enhanced plant growth parameters and led to the reduced levels of lipid peroxidation and higher levels of pigment. In addition, H2O2 pretreatment increased Cr accumulation in aerial parts of seedlings. The tendency of increase in thiol content under Cr(VI) stress was further increased with H2O2 pretreatment. The activities of antioxidant enzymes such as superoxide dismutase (SOD), ascorbate peroxidase (APX), guaiacol peroxidase (POD) and catalase (CAT) were differentially altered. SOD and POD activities increased under Cr(VI) stress, whereas APX and CAT activities decreased. The SOD and CAT activities remained unaffected in both durations due to H2O2 pretreatment, but activities of APX and POD were promoted in the Cr(VI)-stressed seedlings. Metallothioneins are a family of low-molecular-weight Cys-rich proteins and are thought to play a possible role in metal metabolism or detoxification. In real-time quantitative PCR analysis, the expression level of BnMP1 mRNA was increased at 1 day after treatment (DAT), whereas it was decreased at 7 DAT in Cr(VI)-stressed seedlings. At 1 DAT, pretreatment of H2O2 before Cr(VI) stress reduced the expression of BnMP1 mRNA as compared to Cr(VI) stress alone, but this effect was not significant. At 7 DAT, H2O2 pretreatment alleviated the Cr(VI) stress-mediated decrease in the expression of BnMP1 mRNA. These results suggest that H2O2 may act as a signal that triggers defense mechanisms which in turn protects canola seedlings from Cr(VI)-induced oxidative damage.","Protective role of hydrogen peroxide pretreatment on defense systems and BnMP1 gene expression in Cr(VI)-stressed canola seedlings Abs: To evaluate the ameliorating effects of hydrogen peroxide (H2O2, 200 ?M) on hexavalent chromium [Cr(VI)] toxicity in canola (Brassica napus L.), we focused on the plant growth, chlorophyll content, thiol contents, lipid peroxidation, antioxidant enzymes, and the expression of metallothionein protein (BnMP1) mRNA. Cr(VI) at 50 ?M significantly decreased the plant growth (fresh and dry weights). The decrease in growth was accompanied by increased lipid peroxidation and decreased chlorophyll content in leaves. Hydrogen peroxide pretreatment, however, enhanced plant growth parameters and led to the reduced levels of lipid peroxidation and higher levels of pigment. In addition, H2O2 pretreatment increased Cr accumulation in aerial parts of seedlings. The tendency of increase in thiol content under Cr(VI) stress was further increased with H2O2 pretreatment. The activities of antioxidant enzymes such as superoxide dismutase (SOD), ascorbate peroxidase (APX), guaiacol peroxidase (POD) and catalase (CAT) were differentially altered. SOD and POD activities increased under Cr(VI) stress, whereas APX and CAT activities decreased. The SOD and CAT activities remained unaffected in both durations due to H2O2 pretreatment, but activities of APX and POD were promoted in the Cr(VI)-stressed seedlings. Metallothioneins are a family of low-molecular-weight Cys-rich proteins and are thought to play a possible role in metal metabolism or detoxification. In real-time quantitative PCR analysis, the expression level of BnMP1 mRNA was increased at 1 day after treatment (DAT), whereas it was decreased at 7 DAT in Cr(VI)-stressed seedlings. At 1 DAT, pretreatment of H2O2 before Cr(VI) stress reduced the expression of BnMP1 mRNA as compared to Cr(VI) stress alone, but this effect was not significant. At 7 DAT, H2O2 pretreatment alleviated the Cr(VI) stress-mediated decrease in the expression of BnMP1 mRNA. These results suggest that H2O2 may act as a signal that triggers defense mechanisms which in turn protects canola seedlings from Cr(VI)-induced oxidative damage."
2225085,García-Niño et al. 2013,"Curcumin pretreatment prevents potassium dichromate-induced hepatotoxicity, oxidative stress, decreased respiratory complex I activity, and membrane permeability transition pore opening","Curcumin is a polyphenol derived from turmeric with recognized antioxidant properties. Hexavalent chromium is an environmental toxic and carcinogen compound that induces oxidative stress. The objective of this study was to evaluate the potential protective effect of curcumin on the hepatic damage generated by potassium dichromate (K2Cr2O7) in rats. Animals were pretreated daily by 9-10 days with curcumin (400?mg/kg b.w.) before the injection of a single intraperitoneal of K2Cr2O7 (15?mg/kg b.w.). Groups of animals were sacrificed 24 and 48?h later. K2Cr2O7-induced damage to the liver was evident by histological alterations and increase in the liver weight and in the activity of alanine aminotransferase, aspartate aminotransferase, lactate dehydrogenase, and alkaline phosphatase in plasma. In addition, K2Cr2O7 induced oxidative damage in liver and isolated mitochondria, which was evident by the increase in the content of malondialdehyde and protein carbonyl and decrease in the glutathione content and in the activity of several antioxidant enzymes. Moreover, K2Cr2O7 induced decrease in mitochondrial oxygen consumption, in the activity of respiratory complex I, and permeability transition pore opening. All the above-mentioned alterations were prevented by curcumin pretreatment. The beneficial effects of curcumin against K2Cr2O7-induced liver oxidative damage were associated with prevention of mitochondrial dysfunction.","Curcumin pretreatment prevents potassium dichromate-induced hepatotoxicity, oxidative stress, decreased respiratory complex I activity, and membrane permeability transition pore opening Abs: Curcumin is a polyphenol derived from turmeric with recognized antioxidant properties. Hexavalent chromium is an environmental toxic and carcinogen compound that induces oxidative stress. The objective of this study was to evaluate the potential protective effect of curcumin on the hepatic damage generated by potassium dichromate (K2Cr2O7) in rats. Animals were pretreated daily by 9-10 days with curcumin (400?mg/kg b.w.) before the injection of a single intraperitoneal of K2Cr2O7 (15?mg/kg b.w.). Groups of animals were sacrificed 24 and 48?h later. K2Cr2O7-induced damage to the liver was evident by histological alterations and increase in the liver weight and in the activity of alanine aminotransferase, aspartate aminotransferase, lactate dehydrogenase, and alkaline phosphatase in plasma. In addition, K2Cr2O7 induced oxidative damage in liver and isolated mitochondria, which was evident by the increase in the content of malondialdehyde and protein carbonyl and decrease in the glutathione content and in the activity of several antioxidant enzymes. Moreover, K2Cr2O7 induced decrease in mitochondrial oxygen consumption, in the activity of respiratory complex I, and permeability transition pore opening. All the above-mentioned alterations were prevented by curcumin pretreatment. The beneficial effects of curcumin against K2Cr2O7-induced liver oxidative damage were associated with prevention of mitochondrial dysfunction."
2225084,Zeng et al. 2013,Reactive oxygen species play a central role in hexavalent chromium-induced apoptosis in Hep3B cells without the functional roles of p53 and caspase-3,"<strong>BACKGROUND/AIMS: </strong>Hexavalent chromium [Cr(VI)] and its compounds, which have the extensive application in diverse industries including metallurgy, textile and electroplating, are known to be genotoxic and mutagenic to humans. Although it is supported by a large body of literatures that p53 and caspase-3 played key roles in Cr(VI)-induced cytotoxicity, it is clear that Cr(VI) could induce apoptosis either without activating caspase, or in a p53- independent manner.<br /><br /><strong>METHODS: </strong>In the present study, by using Z-VAD-fmk to inhibit caspase-3 in p53-deficient Hep3B cells, we explored the effect of Cr(VI) on apoptosis induction and the related mechanisms when the functions of p53 and caspase were simultaneously blocked.<br /><br /><strong>RESULTS: </strong>We found that Cr(VI) still induced DNA damage, mitochondrial injury, oxidative stress and apoptosis in Hep3B cells without the functional roles of p53 and caspase-3, and the mechanism study revealed that this was in a ROS-dependent manner since NAC co-treatment showed the protective effect against Cr(VI)-induced apoptosis.<br /><br /><strong>CONCLUSION: </strong>Our research has disclosed the mechanism involved in Cr(VI)-induced cytotoxicity following the loss of p53 and caspase-3 functions and shed light on the importance of using antioxidants for primary and secondary prevention in Cr(VI) occupational exposure populations.","Reactive oxygen species play a central role in hexavalent chromium-induced apoptosis in Hep3B cells without the functional roles of p53 and caspase-3 Abs: <strong>BACKGROUND/AIMS: </strong>Hexavalent chromium [Cr(VI)] and its compounds, which have the extensive application in diverse industries including metallurgy, textile and electroplating, are known to be genotoxic and mutagenic to humans. Although it is supported by a large body of literatures that p53 and caspase-3 played key roles in Cr(VI)-induced cytotoxicity, it is clear that Cr(VI) could induce apoptosis either without activating caspase, or in a p53- independent manner.<br /><br /><strong>METHODS: </strong>In the present study, by using Z-VAD-fmk to inhibit caspase-3 in p53-deficient Hep3B cells, we explored the effect of Cr(VI) on apoptosis induction and the related mechanisms when the functions of p53 and caspase were simultaneously blocked.<br /><br /><strong>RESULTS: </strong>We found that Cr(VI) still induced DNA damage, mitochondrial injury, oxidative stress and apoptosis in Hep3B cells without the functional roles of p53 and caspase-3, and the mechanism study revealed that this was in a ROS-dependent manner since NAC co-treatment showed the protective effect against Cr(VI)-induced apoptosis.<br /><br /><strong>CONCLUSION: </strong>Our research has disclosed the mechanism involved in Cr(VI)-induced cytotoxicity following the loss of p53 and caspase-3 functions and shed light on the importance of using antioxidants for primary and secondary prevention in Cr(VI) occupational exposure populations."
2225083,Lou et al. 2013,Role of DNA methylation in cell cycle arrest induced by Cr (VI) in two cell lines,"Hexavalent chromium [Cr(IV)], a well-known industrial waste product and an environmental pollutant, is recognized as a human carcinogen. But its mechanisms of carcinogenicity remain unclear, and recent studies suggest that DNA methylation may play an important role in the carcinogenesis of Cr(IV). The aim of our study was to investigate the effects of Cr(IV) on cell cycle progress, global DNA methylation, and DNA methylation of p16 gene. A human B lymphoblastoid cell line and a human lung cell line A549 were exposed to 5-15 µM potassium dichromate or 1.25-5 µg/cm² lead chromate for 2-24 hours. Cell cycle was arrested at G? phase by both compounds in 24 hours exposure group, but global hypomethylation occurred earlier than cell cycle arrest, and the hypomethylation status maintained for more than 20 hours. The mRNA expression of p16 was significantly up-regulated by Cr(IV), especially by potassium dichromate, and the mRNA expression of cyclin-dependent kinases (CDK4 and CDK6) was significantly down-regulated. But protein expression analysis showed very little change of p16 gene. Both qualitative and quantitative results showed that DNA methylation status of p16 remained unchanged. Collectively, our data suggested that global hypomethylation was possibly responsible for Cr(IV)-induced G? phase arrest, but DNA methylation might not be related to up-regulation of p16 gene by Cr(IV).","Role of DNA methylation in cell cycle arrest induced by Cr (VI) in two cell lines Abs: Hexavalent chromium [Cr(IV)], a well-known industrial waste product and an environmental pollutant, is recognized as a human carcinogen. But its mechanisms of carcinogenicity remain unclear, and recent studies suggest that DNA methylation may play an important role in the carcinogenesis of Cr(IV). The aim of our study was to investigate the effects of Cr(IV) on cell cycle progress, global DNA methylation, and DNA methylation of p16 gene. A human B lymphoblastoid cell line and a human lung cell line A549 were exposed to 5-15 µM potassium dichromate or 1.25-5 µg/cm² lead chromate for 2-24 hours. Cell cycle was arrested at G? phase by both compounds in 24 hours exposure group, but global hypomethylation occurred earlier than cell cycle arrest, and the hypomethylation status maintained for more than 20 hours. The mRNA expression of p16 was significantly up-regulated by Cr(IV), especially by potassium dichromate, and the mRNA expression of cyclin-dependent kinases (CDK4 and CDK6) was significantly down-regulated. But protein expression analysis showed very little change of p16 gene. Both qualitative and quantitative results showed that DNA methylation status of p16 remained unchanged. Collectively, our data suggested that global hypomethylation was possibly responsible for Cr(IV)-induced G? phase arrest, but DNA methylation might not be related to up-regulation of p16 gene by Cr(IV)."
2225080,Long et al. 2013,Cr(VI) reduction by a potent novel alkaliphilic halotolerant strain Pseudochrobactrum saccharolyticum LY10,"A novel Cr(VI)-reducing strain, Pseudochrobactrum saccharolyticum LY10, was isolated and characterized for its high Cr(VI)-reducing ability. Strain LY10 had typical characteristics of alkali-tolerance and halotolerance. Kinetic analysis indicated that the maximum reduction rate was achieved under optimum conditions with initial pH 8.3, 20gL(-1) NaCl, 55mgL(-1) Cr(VI), and 1.47×10(9)cellsmL(-1) of cell concentration. Further mechanism studies verified that the removal of Cr(VI) was mainly achieved by a metabolism-dependent bioreduction process. Strain LY10 accumulated chromium both in and around the cells, with cell walls acting as the major binding sites for chromium. X-ray absorption near-edge structure (XANES) analysis further confirmed that the chromium immobilized by the cells was in the Cr(III) state. In the present study, Pseudochrobactrum saccharolyticum was, for the first time, reported to be a Cr(VI)-reducing bacteria. Results from this research would provide a potential candidate for bioremediation of Cr(VI)-contaminated environments, especially alkaline and saline milieus with Cr(VI) at low-to-mid concentrations.","Cr(VI) reduction by a potent novel alkaliphilic halotolerant strain Pseudochrobactrum saccharolyticum LY10 Abs: A novel Cr(VI)-reducing strain, Pseudochrobactrum saccharolyticum LY10, was isolated and characterized for its high Cr(VI)-reducing ability. Strain LY10 had typical characteristics of alkali-tolerance and halotolerance. Kinetic analysis indicated that the maximum reduction rate was achieved under optimum conditions with initial pH 8.3, 20gL(-1) NaCl, 55mgL(-1) Cr(VI), and 1.47×10(9)cellsmL(-1) of cell concentration. Further mechanism studies verified that the removal of Cr(VI) was mainly achieved by a metabolism-dependent bioreduction process. Strain LY10 accumulated chromium both in and around the cells, with cell walls acting as the major binding sites for chromium. X-ray absorption near-edge structure (XANES) analysis further confirmed that the chromium immobilized by the cells was in the Cr(III) state. In the present study, Pseudochrobactrum saccharolyticum was, for the first time, reported to be a Cr(VI)-reducing bacteria. Results from this research would provide a potential candidate for bioremediation of Cr(VI)-contaminated environments, especially alkaline and saline milieus with Cr(VI) at low-to-mid concentrations."
2225079,Bhattacharya and  Gupta 2013,Evaluation of Acinetobacter sp. B9 for Cr (VI) resistance and detoxification with potential application in bioremediation of heavy-metals-rich industrial wastewater,"Present work demonstrates Cr (VI) detoxification and resistance mechanism of a newly isolated strain (B9) of Acinetobacter sp. Bioremediation potential of the strain B9 is shown by simultaneous removal of major heavy metals including chromium from heavy-metals-rich metal finishing industrial wastewater. Strain B9 tolerate up to 350 mg L(-1) of Cr (VI) and also shows level of tolerance to Ni (II), Zn (II), Pb (II), and Cd (II). The strain was capable of reducing 67 % of initial 7.0 mg L(-1) of Cr (VI) within 24 h of incubation, while in presence of Cu ions 100 % removal of initial 7.0 and 10 mg L(-1) of Cr (VI) was observed with in 24 h. pH in the range of 6.0-8.0 and inoculum size of 2 % (v/v) were determined to be optimum for dichromate reduction. Fourier transform infrared spectroscopy and transmission electron microscopy studies suggested absorption or intracellular accumulation and that might be one of the major mechanisms behind the chromium resistance by strain B9. Scanning electron microscopy showed morphological changes in the strain due to chromium stress. Relevance of the strain for treatment of heavy-metals-rich industrial wastewater resulted in 93.7, 55.4, and 68.94 % removal of initial 30 mg L(-1) Cr (VI), 246 mg L(-1) total Cr, and 51 mg L(-1) Ni, respectively, after 144 h of treatment in a batch mode.","Evaluation of Acinetobacter sp. B9 for Cr (VI) resistance and detoxification with potential application in bioremediation of heavy-metals-rich industrial wastewater Abs: Present work demonstrates Cr (VI) detoxification and resistance mechanism of a newly isolated strain (B9) of Acinetobacter sp. Bioremediation potential of the strain B9 is shown by simultaneous removal of major heavy metals including chromium from heavy-metals-rich metal finishing industrial wastewater. Strain B9 tolerate up to 350 mg L(-1) of Cr (VI) and also shows level of tolerance to Ni (II), Zn (II), Pb (II), and Cd (II). The strain was capable of reducing 67 % of initial 7.0 mg L(-1) of Cr (VI) within 24 h of incubation, while in presence of Cu ions 100 % removal of initial 7.0 and 10 mg L(-1) of Cr (VI) was observed with in 24 h. pH in the range of 6.0-8.0 and inoculum size of 2 % (v/v) were determined to be optimum for dichromate reduction. Fourier transform infrared spectroscopy and transmission electron microscopy studies suggested absorption or intracellular accumulation and that might be one of the major mechanisms behind the chromium resistance by strain B9. Scanning electron microscopy showed morphological changes in the strain due to chromium stress. Relevance of the strain for treatment of heavy-metals-rich industrial wastewater resulted in 93.7, 55.4, and 68.94 % removal of initial 30 mg L(-1) Cr (VI), 246 mg L(-1) total Cr, and 51 mg L(-1) Ni, respectively, after 144 h of treatment in a batch mode."
2225078,Choppala et al. 2013,Chemodynamics of chromium reduction in soils: implications to bioavailability,"Chromium toxicity in soils can be mitigated by reduction of Cr(VI) to Cr(III) which is influenced by the presence of free Cr(VI) species in soil solution, and the supply of protons and electrons. In this study, the effects of Cr(VI) adsorption (i.e. availability of free Cr(VI) species in soil solution), soil pH (i.e. supply of protons) and three electron donor carbon sources [black carbon (BC), chicken manure biochar (CMB) and cow manure (CM)] on the reduction of Cr(VI) to Cr(III) in soils were investigated. The results indicated that the rate of Cr(VI) reduction decreased with an increase in Cr(VI) adsorption and soil pH, which is attributed to decreased supply of free Cr(VI) ions and protons, respectively. Among the three different amendments tested, BC showed the highest rate of Cr(VI) reduction followed by CM and CMB. Furthermore, addition of BC, CM and CMB decreased the bioavailability of Cr(VI) in contaminated soils. The high efficiency of BC on Cr(VI) reduction was due to the electron donor's functional groups such as phenolic, hydroxyl, carbonyl and amides. The study demonstrated that free form of Cr(VI) ions in soil solution and carbon amendments enriched with acidic functional groups favored the reduction of Cr(VI), thereby mitigating its bioavailability and toxicity in contaminated soils.","Chemodynamics of chromium reduction in soils: implications to bioavailability Abs: Chromium toxicity in soils can be mitigated by reduction of Cr(VI) to Cr(III) which is influenced by the presence of free Cr(VI) species in soil solution, and the supply of protons and electrons. In this study, the effects of Cr(VI) adsorption (i.e. availability of free Cr(VI) species in soil solution), soil pH (i.e. supply of protons) and three electron donor carbon sources [black carbon (BC), chicken manure biochar (CMB) and cow manure (CM)] on the reduction of Cr(VI) to Cr(III) in soils were investigated. The results indicated that the rate of Cr(VI) reduction decreased with an increase in Cr(VI) adsorption and soil pH, which is attributed to decreased supply of free Cr(VI) ions and protons, respectively. Among the three different amendments tested, BC showed the highest rate of Cr(VI) reduction followed by CM and CMB. Furthermore, addition of BC, CM and CMB decreased the bioavailability of Cr(VI) in contaminated soils. The high efficiency of BC on Cr(VI) reduction was due to the electron donor's functional groups such as phenolic, hydroxyl, carbonyl and amides. The study demonstrated that free form of Cr(VI) ions in soil solution and carbon amendments enriched with acidic functional groups favored the reduction of Cr(VI), thereby mitigating its bioavailability and toxicity in contaminated soils."
2225077,Huang et al. 2013,Selective removal of Cr(VI) from aqueous solution by adsorption on mangosteen peel,"Mangosteen peel, rich in polyphenolic compounds, was used to prepare the adsorbent exhibiting highly selective adsorption for Cr(VI) over other metal ions such as Pb(2+), Fe(3+), Zn(2+), Cd(2+), and Cr(3+) at the pH values of 1?4. The chemical modification method proposed by using calcium hydroxide is quite cost-effective and ecofriendly without using any toxic reagents or causing any secondary pollution. The adsorption isotherm results revealed that the adsorption of Cr(VI) on the gel fit well the Langmuir adsorption model, and the maximum adsorption capacity for Cr(VI) at pH levels 1, 2, 3, and 4 was evaluated to be 2.46, 2.44, 1.99, and 2.14 mol/kg, respectively. The adsorption mechanism for Cr(VI) on the saponified gel was verified to follow an esterifiaction reaction coupled with the reduction of Cr(VI) to Cr(III) in which H(+) plays a role of promoter. Thus, modified mangosteen peel gel has the prominent selectivity and low cost for Cr(VI) removal.","Selective removal of Cr(VI) from aqueous solution by adsorption on mangosteen peel Abs: Mangosteen peel, rich in polyphenolic compounds, was used to prepare the adsorbent exhibiting highly selective adsorption for Cr(VI) over other metal ions such as Pb(2+), Fe(3+), Zn(2+), Cd(2+), and Cr(3+) at the pH values of 1?4. The chemical modification method proposed by using calcium hydroxide is quite cost-effective and ecofriendly without using any toxic reagents or causing any secondary pollution. The adsorption isotherm results revealed that the adsorption of Cr(VI) on the gel fit well the Langmuir adsorption model, and the maximum adsorption capacity for Cr(VI) at pH levels 1, 2, 3, and 4 was evaluated to be 2.46, 2.44, 1.99, and 2.14 mol/kg, respectively. The adsorption mechanism for Cr(VI) on the saponified gel was verified to follow an esterifiaction reaction coupled with the reduction of Cr(VI) to Cr(III) in which H(+) plays a role of promoter. Thus, modified mangosteen peel gel has the prominent selectivity and low cost for Cr(VI) removal."
2225076,Rawat et al. 2013,Cr(VI) sorption by free and immobilised chromate-reducing bacterial cells in PVA-alginate matrix: equilibrium isotherms and kinetic studies,"Chromate-resistant bacterial strain isolated from the soil of tannery was studied for Cr(VI) bioaccumulation in free and immobilised cells to evaluate its applicability in chromium removal from aqueous solution. Based on the comparative analysis of the 16S rRNA gene, and phenotypic and biochemical characterization, this strain was identified as Paenibacillus xylanilyticus MR12. Mechanism of Cr adsorption was also ascertained by chemical modifications of the bacterial biomass followed by Fourier transform infrared spectroscopy analysis of the cell wall constituents. The equilibrium biosorption analysed using isotherms (Langmuir, Freundlich and Dubinin-Redushkevich) and kinetics models (pseudo-first-order, second-order and Weber-Morris) revealed that the Langmuir model best correlated to experimental data, and Weber-Morris equation well described Cr(VI) biosorption kinetics. Polyvinyl alcohol alginate immobilised cells had the highest Cr(VI) removal efficiency than that of free cells and could also be reused four times for Cr(VI) removal. Complete reduction of chromate in simulated effluent containing Cu(2+), Mg(2+), Mn(2+) and Zn(2+) by immobilised cells, demonstrated potential applications of a novel immobilised bacterial strain MR12, as a vital bioresource in Cr(VI) bioremediation technology.","Cr(VI) sorption by free and immobilised chromate-reducing bacterial cells in PVA-alginate matrix: equilibrium isotherms and kinetic studies Abs: Chromate-resistant bacterial strain isolated from the soil of tannery was studied for Cr(VI) bioaccumulation in free and immobilised cells to evaluate its applicability in chromium removal from aqueous solution. Based on the comparative analysis of the 16S rRNA gene, and phenotypic and biochemical characterization, this strain was identified as Paenibacillus xylanilyticus MR12. Mechanism of Cr adsorption was also ascertained by chemical modifications of the bacterial biomass followed by Fourier transform infrared spectroscopy analysis of the cell wall constituents. The equilibrium biosorption analysed using isotherms (Langmuir, Freundlich and Dubinin-Redushkevich) and kinetics models (pseudo-first-order, second-order and Weber-Morris) revealed that the Langmuir model best correlated to experimental data, and Weber-Morris equation well described Cr(VI) biosorption kinetics. Polyvinyl alcohol alginate immobilised cells had the highest Cr(VI) removal efficiency than that of free cells and could also be reused four times for Cr(VI) removal. Complete reduction of chromate in simulated effluent containing Cu(2+), Mg(2+), Mn(2+) and Zn(2+) by immobilised cells, demonstrated potential applications of a novel immobilised bacterial strain MR12, as a vital bioresource in Cr(VI) bioremediation technology."
2225075,Choi et al. 2013,Malignant fibrous histiocytoma of the maxillary sinus in a spray painter from an automobile repair shop,"<strong>BACKGROUND: </strong>We report a case of a spray painter who developed malignant fibrous histiocytoma (MFH) of the maxillary sinus following long-term exposure to chromium, nickel, and formaldehyde, implying that these agents are probable causal agents of MFH.<br /><br /><strong>CASE REPORT: </strong>The patient developed right-sided prosopalgia that began twenty months ago. The symptom persisted despite medical treatment. After two months, he was diagnosed with MFH through imaging studies, surgery, and pathological microscopic findings at a university hospital in Seoul. His social, medical, and family history was unremarkable.The patient had worked for about 18 years at an automobile repair shop as a spray painter. During this period, he had been exposed to various occupational agents, such as hexavalent chromium, nickel, and formaldehyde, without appropriate personal protective equipment. He painted 6 days a week and worked for about 8 hours a day.Investigation of the patient's work environment detected hexavalent chromium, chromate, nickel, and formaldehyde.<br /><br /><strong>CONCLUSIONS: </strong>The study revealed that the patient had been exposed to hexavalent chromium, formaldehyde, and nickel compounds through sanding and spray painting. The association between paranasal cancer and exposure to the aforementioned occupational human carcinogens has been established. We suggest, in this case, the possibility that the paint spraying acted as a causal agent for paranasal cancer.","Malignant fibrous histiocytoma of the maxillary sinus in a spray painter from an automobile repair shop Abs: <strong>BACKGROUND: </strong>We report a case of a spray painter who developed malignant fibrous histiocytoma (MFH) of the maxillary sinus following long-term exposure to chromium, nickel, and formaldehyde, implying that these agents are probable causal agents of MFH.<br /><br /><strong>CASE REPORT: </strong>The patient developed right-sided prosopalgia that began twenty months ago. The symptom persisted despite medical treatment. After two months, he was diagnosed with MFH through imaging studies, surgery, and pathological microscopic findings at a university hospital in Seoul. His social, medical, and family history was unremarkable.The patient had worked for about 18 years at an automobile repair shop as a spray painter. During this period, he had been exposed to various occupational agents, such as hexavalent chromium, nickel, and formaldehyde, without appropriate personal protective equipment. He painted 6 days a week and worked for about 8 hours a day.Investigation of the patient's work environment detected hexavalent chromium, chromate, nickel, and formaldehyde.<br /><br /><strong>CONCLUSIONS: </strong>The study revealed that the patient had been exposed to hexavalent chromium, formaldehyde, and nickel compounds through sanding and spray painting. The association between paranasal cancer and exposure to the aforementioned occupational human carcinogens has been established. We suggest, in this case, the possibility that the paint spraying acted as a causal agent for paranasal cancer."
2225074,Saha et al. ,Combination of best promoter and micellar catalyst for chromic acid oxidation of 1-butanol to 1-butanal in aqueous media at room temperature,"In aqueous acidic media, picolinic acid, 2,2'-bipyridine and 1,10-phenanthroline promoted Cr(VI) oxidation of 1-butanol produces 1-butanal. 1-butanal is separated from mixture by fractional distillation. The anionic surfactant (SDS) and neutral surfactant (TX-100) accelerate the process while the cationic surfactant (CPC) retards the reaction. Combination of bipy and SDS is the best choice for chromic acid oxidation of 1-butanol to 1-butanal in aqueous media.","Combination of best promoter and micellar catalyst for chromic acid oxidation of 1-butanol to 1-butanal in aqueous media at room temperature Abs: In aqueous acidic media, picolinic acid, 2,2'-bipyridine and 1,10-phenanthroline promoted Cr(VI) oxidation of 1-butanol produces 1-butanal. 1-butanal is separated from mixture by fractional distillation. The anionic surfactant (SDS) and neutral surfactant (TX-100) accelerate the process while the cationic surfactant (CPC) retards the reaction. Combination of bipy and SDS is the best choice for chromic acid oxidation of 1-butanol to 1-butanal in aqueous media."
2225073,Novotnik et al. ,"Inhibition of the nitrification process in activated sludge by trivalent and hexavalent chromium, and partitioning of hexavalent chromium between sludge compartments","The input of wastewater treatment plants (WWTPs) may contain high concentrations of Cr(III) and Cr(VI), which can affect nitrogen removal. In the present study the influence of different Cr(III) and Cr(VI) concentrations towards activated sludge nitrification was studied. To better understand the mechanisms of Cr(VI) toxicity, its reduction, adsorption and uptake in activated sludge was investigated in a batch growth system. Quantification of Cr(VI) was performed by speciated isotope dilution inductively coupled plasma mass spectrometry. It was found that Cr(VI) concentrations above 1.0mgL(-1) and Cr(III) concentrations higher than 50mgL(-1) negatively affected nitrification. Speciation studies indicated almost complete reduction of Cr(VI) after 24h of incubation when Cr(VI) concentrations were lower than 2.5mgL(-1), whereas for Cr(VI) added to 5mgL(-1) around 40% remained unreduced. The study of the partitioning of Cr in the activated sludge was performed by the addition of Cr(VI) in concentrations of 2.5 and 5.0mgL(-1). Results revealed that Cr was allocated mainly within the intercellular compartments, whereas intracellular and adsorbed Cr represented less than 0.1% of the Cr sludge concentrations. Cr(VI) was reduced in all compartments, the most efficiently (about 94%) within the intracellular and intercellular fractions. The extent of reduction of adsorbed Cr was 92% and 80% for 2.5 and 5.0mg of Cr(VI) L(-1), respectively. The results of present investigation provide a new insight into the toxicity of Cr species towards activated sludge nitrification, which is of significant importance for the management of WWTPs in order to prevent them from inflows containing harmful Cr(VI) concentrations.","Inhibition of the nitrification process in activated sludge by trivalent and hexavalent chromium, and partitioning of hexavalent chromium between sludge compartments Abs: The input of wastewater treatment plants (WWTPs) may contain high concentrations of Cr(III) and Cr(VI), which can affect nitrogen removal. In the present study the influence of different Cr(III) and Cr(VI) concentrations towards activated sludge nitrification was studied. To better understand the mechanisms of Cr(VI) toxicity, its reduction, adsorption and uptake in activated sludge was investigated in a batch growth system. Quantification of Cr(VI) was performed by speciated isotope dilution inductively coupled plasma mass spectrometry. It was found that Cr(VI) concentrations above 1.0mgL(-1) and Cr(III) concentrations higher than 50mgL(-1) negatively affected nitrification. Speciation studies indicated almost complete reduction of Cr(VI) after 24h of incubation when Cr(VI) concentrations were lower than 2.5mgL(-1), whereas for Cr(VI) added to 5mgL(-1) around 40% remained unreduced. The study of the partitioning of Cr in the activated sludge was performed by the addition of Cr(VI) in concentrations of 2.5 and 5.0mgL(-1). Results revealed that Cr was allocated mainly within the intercellular compartments, whereas intracellular and adsorbed Cr represented less than 0.1% of the Cr sludge concentrations. Cr(VI) was reduced in all compartments, the most efficiently (about 94%) within the intracellular and intercellular fractions. The extent of reduction of adsorbed Cr was 92% and 80% for 2.5 and 5.0mg of Cr(VI) L(-1), respectively. The results of present investigation provide a new insight into the toxicity of Cr species towards activated sludge nitrification, which is of significant importance for the management of WWTPs in order to prevent them from inflows containing harmful Cr(VI) concentrations."
2225072,Stefaniak et al. 2014,"Dissolution of the metal sensitizers Ni, Be, Cr in artificial sweat to improve estimates of dermal bioaccessibility","Dermal exposure to sensitizing metals is a serious occupational and public health problem. The usual approach to dermal exposure assessment is to process samples by chemical methods that use reactants to digest the metal particles and quantify the mass. In the case of dermal exposure assessment, these reactants are not representative of the skin surface film liquids and hence, may overestimate bioaccessibility. We hypothesize that the amount and form of sensitizer on a sample that leaches in a biological fluid, as can be estimated using artificial sweat, may be a more relevant metric for assessing health risks. Beryllium metal (Be), nickel metal (Ni), and chromium carbide (Cr3C2) particles were characterized and masses of sensitizing ions were measured using established reactant-assisted digestion procedures and extraction in artificial sweat under physiologically relevant conditions. Chromium ions released into artificial sweat were speciated to understand valence states. The ratios of the fraction of metal dissolved in artificial sweat relative to that dissolved by chemical-specific reactants were 1/2 (Be), 1/108 (Ni), and 1/2500 (Cr). The divalent Be and Ni cations were stable in artificial sweat over time (did not precipitate) whereas hexavalent chromium [Cr(vi)] ions decayed over time. Further analysis using speciated isotope dilution mass spectrometry revealed that the decay of Cr(vi) was accompanied by the formation of Cr(iii) in the sweat model. Use of reactant-assisted analytical chemistry to quantify amounts of metal sensitizers on samples could overestimate biologically relevant exposure. In addition to mass, the valence state also influences penetration through the outer stratum corneum of the skin and is an important consideration when assessing exposure to complex sensitizers such as Cr which have multiple valence states with differing penetration efficiencies.","Dissolution of the metal sensitizers Ni, Be, Cr in artificial sweat to improve estimates of dermal bioaccessibility Abs: Dermal exposure to sensitizing metals is a serious occupational and public health problem. The usual approach to dermal exposure assessment is to process samples by chemical methods that use reactants to digest the metal particles and quantify the mass. In the case of dermal exposure assessment, these reactants are not representative of the skin surface film liquids and hence, may overestimate bioaccessibility. We hypothesize that the amount and form of sensitizer on a sample that leaches in a biological fluid, as can be estimated using artificial sweat, may be a more relevant metric for assessing health risks. Beryllium metal (Be), nickel metal (Ni), and chromium carbide (Cr3C2) particles were characterized and masses of sensitizing ions were measured using established reactant-assisted digestion procedures and extraction in artificial sweat under physiologically relevant conditions. Chromium ions released into artificial sweat were speciated to understand valence states. The ratios of the fraction of metal dissolved in artificial sweat relative to that dissolved by chemical-specific reactants were 1/2 (Be), 1/108 (Ni), and 1/2500 (Cr). The divalent Be and Ni cations were stable in artificial sweat over time (did not precipitate) whereas hexavalent chromium [Cr(vi)] ions decayed over time. Further analysis using speciated isotope dilution mass spectrometry revealed that the decay of Cr(vi) was accompanied by the formation of Cr(iii) in the sweat model. Use of reactant-assisted analytical chemistry to quantify amounts of metal sensitizers on samples could overestimate biologically relevant exposure. In addition to mass, the valence state also influences penetration through the outer stratum corneum of the skin and is an important consideration when assessing exposure to complex sensitizers such as Cr which have multiple valence states with differing penetration efficiencies."
2225071,Chakraborty et al. 2014,Kinetic evaluation of chromium(VI) sorption by water lettuce (Pistia),"An investigation was performed to evaluate the uptake capacity of Pistia in living condition for adsorptive removal of chromium(VI) from spiked solution for examining a remedial measure for disposal of chrome-laden wastewater in an urban wetland system. Kinetics results show about 78% removal was achieved for 3 mg/L initial concentration of Cr(VI). Experimental data showed that the root portion absorbed more Cr(VI) (28.54 ?g/g) compared to accumulation in leaf (5.73 ?g/g). It was also noted that the plant could effectively remove Cr(VI) from the solution with minor damage up to an initial Cr(VI) concentration of 3 mg/L, for which the adsorption isotherm studies were conducted. The maximum uptake capacity of the plant was recorded as 0.05 mg/g of Cr(VI) at the equilibrium level after a contact period of 7 days for an initial concentration of 8 mg /L, although severe physiological damage occurred. The experimental results were plotted in Langmuir and Freundlich isotherm models and both were found to be well fitted (r(2) = 0.979 and r(2) = 0.974 respectively). The high value of n (2.16) reveals a strong bond between the plant root and dissolved Cr(VI), which favours the adsorption process. The order of the reaction was also examined on the basis of uptake capacity and it was found that the second order model fitted best.","Kinetic evaluation of chromium(VI) sorption by water lettuce (Pistia) Abs: An investigation was performed to evaluate the uptake capacity of Pistia in living condition for adsorptive removal of chromium(VI) from spiked solution for examining a remedial measure for disposal of chrome-laden wastewater in an urban wetland system. Kinetics results show about 78% removal was achieved for 3 mg/L initial concentration of Cr(VI). Experimental data showed that the root portion absorbed more Cr(VI) (28.54 ?g/g) compared to accumulation in leaf (5.73 ?g/g). It was also noted that the plant could effectively remove Cr(VI) from the solution with minor damage up to an initial Cr(VI) concentration of 3 mg/L, for which the adsorption isotherm studies were conducted. The maximum uptake capacity of the plant was recorded as 0.05 mg/g of Cr(VI) at the equilibrium level after a contact period of 7 days for an initial concentration of 8 mg /L, although severe physiological damage occurred. The experimental results were plotted in Langmuir and Freundlich isotherm models and both were found to be well fitted (r(2) = 0.979 and r(2) = 0.974 respectively). The high value of n (2.16) reveals a strong bond between the plant root and dissolved Cr(VI), which favours the adsorption process. The order of the reaction was also examined on the basis of uptake capacity and it was found that the second order model fitted best."
2225070,Kim et al. 2013,Exposure assessment suggests exposure to lung cancer carcinogens in a painter working in an automobile bumper shop,"A 46-year-old man who had worked as a bumper spray painter in an automobile body shop for 15 years developed lung cancer. The patient was a nonsmoker with no family history of lung cancer. To determine whether the cancer was related to his work environment, we assessed the level of exposure to carcinogens during spray painting, sanding, and heat treatment. The results showed that spray painting with yellow paint increased the concentration of hexavalent chromium in the air to as much as 118.33 ?g/m(3). Analysis of the paint bulk materials showed that hexavalent chromium was mostly found in the form of lead chromate. Interestingly, strontium chromate was also detected, and the concentration of strontium chromate increased in line with the brightness of the yellow color. Some paints contained about 1% crystalline silica in the form of quartz.","Exposure assessment suggests exposure to lung cancer carcinogens in a painter working in an automobile bumper shop Abs: A 46-year-old man who had worked as a bumper spray painter in an automobile body shop for 15 years developed lung cancer. The patient was a nonsmoker with no family history of lung cancer. To determine whether the cancer was related to his work environment, we assessed the level of exposure to carcinogens during spray painting, sanding, and heat treatment. The results showed that spray painting with yellow paint increased the concentration of hexavalent chromium in the air to as much as 118.33 ?g/m(3). Analysis of the paint bulk materials showed that hexavalent chromium was mostly found in the form of lead chromate. Interestingly, strontium chromate was also detected, and the concentration of strontium chromate increased in line with the brightness of the yellow color. Some paints contained about 1% crystalline silica in the form of quartz."
2225069,Suh et al. 2014,High concentrations of hexavalent chromium in drinking water alter iron homeostasis in F344 rats and B6C3F1 mice,"Hexavalent chromium [Cr(VI)] induces hematological signs of microcytic anemia in rodents. Considering that Cr(VI) can oxidize ferrous (Fe(2+)) to ferric (Fe(3+)) iron, and that only the former is transported across the duodenum, we hypothesize that, at high concentrations, Cr(VI) oxidizes Fe(2+) in the lumen of the small intestine and perturbs iron absorption. Herein we report that 90-day exposure to Cr(VI) in drinking water resulted in dose-dependent decreases in Fe levels in the duodenum, liver, serum, and bone marrow. Toxicogenomic analyses from the duodenum indicate responses consistent with Fe deficiency, including significant induction of divalent metal transporter 1 (DMT1, Slc11a2) and transferrin receptor 1 (TFR1, Tfr1). In addition, at ?20mg Cr(VI)/L in drinking water, Cr RBC:plasma ratios in rats were increased and exceeded unity, indicating saturation of reductive capacity and intracellular absorption of Cr(VI) into red blood cells (RBCs). These effects occurred in both species but were generally more severe in rats. These data suggest that high concentrations of Cr(VI) in drinking limit Fe absorption and alter iron homeostasis. Furthermore, some effects observed at high doses in recent Cr(VI) chronic and subchronic bioassays may be explained, at least in part, by iron deficiency and disruption of homeostasis.","High concentrations of hexavalent chromium in drinking water alter iron homeostasis in F344 rats and B6C3F1 mice Abs: Hexavalent chromium [Cr(VI)] induces hematological signs of microcytic anemia in rodents. Considering that Cr(VI) can oxidize ferrous (Fe(2+)) to ferric (Fe(3+)) iron, and that only the former is transported across the duodenum, we hypothesize that, at high concentrations, Cr(VI) oxidizes Fe(2+) in the lumen of the small intestine and perturbs iron absorption. Herein we report that 90-day exposure to Cr(VI) in drinking water resulted in dose-dependent decreases in Fe levels in the duodenum, liver, serum, and bone marrow. Toxicogenomic analyses from the duodenum indicate responses consistent with Fe deficiency, including significant induction of divalent metal transporter 1 (DMT1, Slc11a2) and transferrin receptor 1 (TFR1, Tfr1). In addition, at ?20mg Cr(VI)/L in drinking water, Cr RBC:plasma ratios in rats were increased and exceeded unity, indicating saturation of reductive capacity and intracellular absorption of Cr(VI) into red blood cells (RBCs). These effects occurred in both species but were generally more severe in rats. These data suggest that high concentrations of Cr(VI) in drinking limit Fe absorption and alter iron homeostasis. Furthermore, some effects observed at high doses in recent Cr(VI) chronic and subchronic bioassays may be explained, at least in part, by iron deficiency and disruption of homeostasis."
2225068,Yu and  Zhang ,Kinetics for adsorptive removal of chromium(VI) from aqueous solutions by ferri hydroxide/oxohydroxides,"Adsorption behaviors of chromate(VI) on two different iron oxides were investigated through batch experiments under different operational conditions. The operational variables studied included sorbent doses, sorbent species, solution pH, contact time, and initial metal ion concentrations. Both ferri hydroxide and ferri oxohydroxides were capable of removing Cr(VI) from aqueous solution effectively. The extent of metal ion removed from aqueous solution by both sorbents increased with increasing contact time and initial metal ion concentrations, while decreased with elevating solution pH initially. Sorption equilibrium time was observed in 150 min. Equilibrium isotherm data were analyzed using the Langmuir and Freundlich isotherms. The Freundlich model yields a better fit than the Langmuir model. Although kinetic measurements with both sorbents had a similar pattern, ferri hydroxide always showed higher sorptive potential for Cr(VI) than ferri oxohydroxides. Results also indicated that sorptive removal of Cr(VI) by both sorbents was observed to be negative in response to solution pH, due to changes in speciation of Cr(VI) in aqueous solution. At pH lower than 3.0, both iron oxides exhibited much greater capacities of removing Cr(VI) from aqueous solution than other treatments. Therefore, it is to conclude that adsorptive removal of Cr(VI) by both iron oxides is effective. Adsorption capacity is mainly determined by speciation of Cr(VI) in solutions, which is controlled and driven by solution pH.","Kinetics for adsorptive removal of chromium(VI) from aqueous solutions by ferri hydroxide/oxohydroxides Abs: Adsorption behaviors of chromate(VI) on two different iron oxides were investigated through batch experiments under different operational conditions. The operational variables studied included sorbent doses, sorbent species, solution pH, contact time, and initial metal ion concentrations. Both ferri hydroxide and ferri oxohydroxides were capable of removing Cr(VI) from aqueous solution effectively. The extent of metal ion removed from aqueous solution by both sorbents increased with increasing contact time and initial metal ion concentrations, while decreased with elevating solution pH initially. Sorption equilibrium time was observed in 150 min. Equilibrium isotherm data were analyzed using the Langmuir and Freundlich isotherms. The Freundlich model yields a better fit than the Langmuir model. Although kinetic measurements with both sorbents had a similar pattern, ferri hydroxide always showed higher sorptive potential for Cr(VI) than ferri oxohydroxides. Results also indicated that sorptive removal of Cr(VI) by both sorbents was observed to be negative in response to solution pH, due to changes in speciation of Cr(VI) in aqueous solution. At pH lower than 3.0, both iron oxides exhibited much greater capacities of removing Cr(VI) from aqueous solution than other treatments. Therefore, it is to conclude that adsorptive removal of Cr(VI) by both iron oxides is effective. Adsorption capacity is mainly determined by speciation of Cr(VI) in solutions, which is controlled and driven by solution pH."
2225067,Panda and  Sarkar 2014,Biosensing and bioremediation of Cr(VI) by cell free extract of Enterobacter aerogenes T2,"Hexavalent chromium or Cr(VI) enters the environment through several anthropogenic activities and it is highly toxic and carcinogenic. Hence it is required to be detected and remediated from the environment. In this study, low-cost and environment-friendly methods of biosensing and bioremediation of Cr(VI) have been proposed. Crude cell free extract (CFE) of previously isolated Enterobacter aerogenes T2 (GU265554; NII 1111) was prepared and exploited to develop a stable biosensor for direct estimation of Cr(VI) in waste water, by using three electrodes via cyclic voltammetry. For bioremediation studies, a homogeneous solution of commercially available sodium alginate and CFE was added dropwise in a continuously stirred calcium chloride solution. Biologically modified calcium alginate beads were produced and these were further utilized for bioremediation studies. The proposed sensor showed linear response in the range of 10-40 ?g L(-1) Cr(VI) and the limit of detection was found to be 6.6 ?g L(-1) Cr(VI). No interference was observed in presence of metal ions, e.g., lead, cadmium, arsenic, tin etc., except for insignificant interference with molybdenum and manganese. In bioremediation studies, modified calcium alginate beads showed encouraging removal rate 900 mg Cr(VI)/m(3) water per day with a removal efficiency of 90%, much above than reported in literature. The proposed sensing system could be a viable alternative to costly measurement procedures. Calcium alginate beads, modified with CFE of E. aerogenes, could be used in bioremediation of Cr(VI) since it could work in real conditions with extraordinarily high capacity.","Biosensing and bioremediation of Cr(VI) by cell free extract of Enterobacter aerogenes T2 Abs: Hexavalent chromium or Cr(VI) enters the environment through several anthropogenic activities and it is highly toxic and carcinogenic. Hence it is required to be detected and remediated from the environment. In this study, low-cost and environment-friendly methods of biosensing and bioremediation of Cr(VI) have been proposed. Crude cell free extract (CFE) of previously isolated Enterobacter aerogenes T2 (GU265554; NII 1111) was prepared and exploited to develop a stable biosensor for direct estimation of Cr(VI) in waste water, by using three electrodes via cyclic voltammetry. For bioremediation studies, a homogeneous solution of commercially available sodium alginate and CFE was added dropwise in a continuously stirred calcium chloride solution. Biologically modified calcium alginate beads were produced and these were further utilized for bioremediation studies. The proposed sensor showed linear response in the range of 10-40 ?g L(-1) Cr(VI) and the limit of detection was found to be 6.6 ?g L(-1) Cr(VI). No interference was observed in presence of metal ions, e.g., lead, cadmium, arsenic, tin etc., except for insignificant interference with molybdenum and manganese. In bioremediation studies, modified calcium alginate beads showed encouraging removal rate 900 mg Cr(VI)/m(3) water per day with a removal efficiency of 90%, much above than reported in literature. The proposed sensing system could be a viable alternative to costly measurement procedures. Calcium alginate beads, modified with CFE of E. aerogenes, could be used in bioremediation of Cr(VI) since it could work in real conditions with extraordinarily high capacity."
2225066,Lv et al. 2014,Nanoscale Zero-Valent Iron (nZVI) assembled on magnetic Fe3O4/graphene for Chromium (VI) removal from aqueous solution,"Nanoscale Zero-Valent Iron (nZVI) assembled on magnetic Fe3O4/graphene (nZVI@MG) nanocomposites was synthesized for Cr(VI) removal from aqueous solution. nZVI particles were perfectly dispersed either among Fe3O4 nanoparticles (Fe3O4 NPs) or above the basal plane of graphene. This material shows Cr(VI) removal efficiency of 83.8%, much higher than those of individuals (18.0% for nZVI, 21.6% for Fe3O4 NPs and 23.7% for graphene) and even their sum of 63.3%. The removal process obeys pseudo-second-order adsorption model, suggesting that adsorption is rate-controlling step. Maximum Cr(VI) adsorption capacity varies from 66.2 to 101.0mgg(-1) with decreasing pH from 8.0 to 3.0 at 30°C. Negative ?G and ?H indicate spontaneous tendency and exothermic nature. Robust performance of nZVI@MG arises from the formation of micro-nZVI-graphene/nZVI-Fe3O4 batteries and strong adsorption capability of broad graphene sheet/Fe3O4 surfaces. Electrons released by nZVI spread all over the surfaces of graphene and Fe3O4, and the adsorbed Cr(VI) ions on them capture these floating electrons and reduce to Cr(III). Fe3O4 NPs also served as protection shell to prevent nZVI from agglomeration and passivation.","Nanoscale Zero-Valent Iron (nZVI) assembled on magnetic Fe3O4/graphene for Chromium (VI) removal from aqueous solution Abs: Nanoscale Zero-Valent Iron (nZVI) assembled on magnetic Fe3O4/graphene (nZVI@MG) nanocomposites was synthesized for Cr(VI) removal from aqueous solution. nZVI particles were perfectly dispersed either among Fe3O4 nanoparticles (Fe3O4 NPs) or above the basal plane of graphene. This material shows Cr(VI) removal efficiency of 83.8%, much higher than those of individuals (18.0% for nZVI, 21.6% for Fe3O4 NPs and 23.7% for graphene) and even their sum of 63.3%. The removal process obeys pseudo-second-order adsorption model, suggesting that adsorption is rate-controlling step. Maximum Cr(VI) adsorption capacity varies from 66.2 to 101.0mgg(-1) with decreasing pH from 8.0 to 3.0 at 30°C. Negative ?G and ?H indicate spontaneous tendency and exothermic nature. Robust performance of nZVI@MG arises from the formation of micro-nZVI-graphene/nZVI-Fe3O4 batteries and strong adsorption capability of broad graphene sheet/Fe3O4 surfaces. Electrons released by nZVI spread all over the surfaces of graphene and Fe3O4, and the adsorbed Cr(VI) ions on them capture these floating electrons and reduce to Cr(III). Fe3O4 NPs also served as protection shell to prevent nZVI from agglomeration and passivation."
2225065,Najafi et al. 2013,Liver Aspartate Transaminase Isoenzymes as Biomarkers of Chronic Exposure to Chromium(VI) / JETRENI IZOENZIMI ASPARTAT TRANSAMINAZE KAO BIOPOKAZATELJI KRONI?NE IZLOŽENOSTI HEKSAVALENTNOM KROMU,"Abstract Exposure to hexavalent chromium compounds is associated with the risk of lung cancer, dermatitis, gastrointestinal ulcers, and other tissue damages. The aim of this study was to compare liver isoenzyme and total serum activities of aspartate aminotransferase (AST) as cytotoxic biomarkers of acute and chronic cytotoxicity of CrVI. We investigated the extent of cell damage caused by chromium(VI) in acute (2.5 mg kg-1) daily doses administered over five days and chronic (0.25 mg kg-1 and 0.5 mg kg-1) daily doses administered over 15 to 60 days by measuring total AST in serum and low molecular weight AST (LMW-AST) and high molecular weight AST (HMW-AST) activities in thirty liver fractions. We also evaluated the kinetic properties and electrophoretic mobility of the LMW- and HMW-AST isoenzymes in liver subcellular fractions. Liver LMW-AST and total serum AST activities significantly decreased after 15 days of exposure (P&lt;0.05). With continued treatment, AST activity increased by 15.67 % (P&lt;0.05). Interestingly, changes in serum AST activity were similar to changes in the liver LMW-AST isoenzyme. Our results confirmed that total serum AST activity may serve as a reliable tissue biomarker for long-term exposures to CrVI, but they also suggest that the LMW-AST isoenzyme could be even more sensitive.","Liver Aspartate Transaminase Isoenzymes as Biomarkers of Chronic Exposure to Chromium(VI) / JETRENI IZOENZIMI ASPARTAT TRANSAMINAZE KAO BIOPOKAZATELJI KRONI?NE IZLOŽENOSTI HEKSAVALENTNOM KROMU Abs: Abstract Exposure to hexavalent chromium compounds is associated with the risk of lung cancer, dermatitis, gastrointestinal ulcers, and other tissue damages. The aim of this study was to compare liver isoenzyme and total serum activities of aspartate aminotransferase (AST) as cytotoxic biomarkers of acute and chronic cytotoxicity of CrVI. We investigated the extent of cell damage caused by chromium(VI) in acute (2.5 mg kg-1) daily doses administered over five days and chronic (0.25 mg kg-1 and 0.5 mg kg-1) daily doses administered over 15 to 60 days by measuring total AST in serum and low molecular weight AST (LMW-AST) and high molecular weight AST (HMW-AST) activities in thirty liver fractions. We also evaluated the kinetic properties and electrophoretic mobility of the LMW- and HMW-AST isoenzymes in liver subcellular fractions. Liver LMW-AST and total serum AST activities significantly decreased after 15 days of exposure (P&lt;0.05). With continued treatment, AST activity increased by 15.67 % (P&lt;0.05). Interestingly, changes in serum AST activity were similar to changes in the liver LMW-AST isoenzyme. Our results confirmed that total serum AST activity may serve as a reliable tissue biomarker for long-term exposures to CrVI, but they also suggest that the LMW-AST isoenzyme could be even more sensitive."
2225064,Somenahally et al. 2013,Hexavalent Chromium Reduction under Fermentative Conditions with Lactate Stimulated Native Microbial Communities,"Microbial reduction of toxic hexavalent chromium (Cr(VI)) in-situ is a plausible bioremediation strategy in electron-acceptor limited environments. However, higher [Cr(VI)] may impose stress on syntrophic communities and impact community structure and function. The study objectives were to understand the impacts of Cr(VI) concentrations on community structure and on the Cr(VI)-reduction potential of groundwater communities at Hanford, WA. Steady state continuous flow bioreactors were used to grow native communities enriched with lactate (30 mM) and continuously amended with Cr(VI) at 0.0 (No-Cr), 0.1 (Low-Cr) and 3.0 (High-Cr) mg/L. Microbial growth, metabolites, Cr(VI), 16S rRNA gene sequences and GeoChip based functional gene composition were monitored for 15 weeks. Temporal trends and differences in growth, metabolite profiles, and community composition were observed, largely between Low-Cr and High-Cr bioreactors. In both High-Cr and Low-Cr bioreactors, Cr(VI) levels were below detection from week 1 until week 15. With lactate enrichment, native bacterial diversity substantially decreased as Pelosinus spp., and Sporotalea spp., became the dominant groups, but did not significantly differ between Cr concentrations. The Archaea diversity also substantially decreased after lactate enrichment from Methanosaeta (35%), Methanosarcina (17%) and others, to mostly Methanosarcina spp. (95%). Methane production was lower in High-Cr reactors suggesting some inhibition of methanogens. Several key functional genes were distinct in Low-Cr bioreactors compared to High-Cr. Among the Cr resistant microbes, Burkholderia vietnamiensis, Comamonas testosterone and Ralstonia pickettii proliferated in Cr amended bioreactors. In-situ fermentative conditions facilitated Cr(VI) reduction, and as a result 3.0 mg/L Cr(VI) did not impact the overall bacterial community structure.","Hexavalent Chromium Reduction under Fermentative Conditions with Lactate Stimulated Native Microbial Communities Abs: Microbial reduction of toxic hexavalent chromium (Cr(VI)) in-situ is a plausible bioremediation strategy in electron-acceptor limited environments. However, higher [Cr(VI)] may impose stress on syntrophic communities and impact community structure and function. The study objectives were to understand the impacts of Cr(VI) concentrations on community structure and on the Cr(VI)-reduction potential of groundwater communities at Hanford, WA. Steady state continuous flow bioreactors were used to grow native communities enriched with lactate (30 mM) and continuously amended with Cr(VI) at 0.0 (No-Cr), 0.1 (Low-Cr) and 3.0 (High-Cr) mg/L. Microbial growth, metabolites, Cr(VI), 16S rRNA gene sequences and GeoChip based functional gene composition were monitored for 15 weeks. Temporal trends and differences in growth, metabolite profiles, and community composition were observed, largely between Low-Cr and High-Cr bioreactors. In both High-Cr and Low-Cr bioreactors, Cr(VI) levels were below detection from week 1 until week 15. With lactate enrichment, native bacterial diversity substantially decreased as Pelosinus spp., and Sporotalea spp., became the dominant groups, but did not significantly differ between Cr concentrations. The Archaea diversity also substantially decreased after lactate enrichment from Methanosaeta (35%), Methanosarcina (17%) and others, to mostly Methanosarcina spp. (95%). Methane production was lower in High-Cr reactors suggesting some inhibition of methanogens. Several key functional genes were distinct in Low-Cr bioreactors compared to High-Cr. Among the Cr resistant microbes, Burkholderia vietnamiensis, Comamonas testosterone and Ralstonia pickettii proliferated in Cr amended bioreactors. In-situ fermentative conditions facilitated Cr(VI) reduction, and as a result 3.0 mg/L Cr(VI) did not impact the overall bacterial community structure."
2225063,Sun et al. 2014,"SBA-15-incorporated nanoscale zero-valent iron particles for chromium(VI) removal from groundwater: Mechanism, effect of pH, humic acid and sustained reactivity","Nanoscale zero-valent iron particles (NZVIs) were incorporated inside the channels of SBA-15 rods by a &quot;two solvents&quot; reduction technique and used to remove Cr(VI) from groundwater. The resulting NZVIs/SBA-15 composites before and after reaction were characterized by N2 adsorption/desorption, X-ray diffraction (XRD), transmission electron microscopy (TEM) and X-ray photoelectron spectroscopy (XPS). Results helped to propose the mechanism of Cr(VI) removal by NZVIs/SBA-15, where Cr(VI) in aqueous was firstly impregnated into the channels of the silica, then adsorbed on the surfaces of the incorporated NZVIs and reduced to Cr(III) directly in the inner pores of the silica. Corrosion products included Fe2O3, FeO(OH), Fe3O4 and Cr2FeO4. Batch experiments revealed that Cr(VI) removal decreased from 99.7% to 92.8% when the initial solution pH increased from 5.5 to 9.0, accompanied by the decrease of the kobs from 0.600 to 0.024min(-1). Humic acid (HA) had a little effect on the removal efficiency of Cr(VI) by NZVIs/SBA-15 but could decrease the reduction rate. The stable reduction of NZVIs/SBA-15 was observed within six cycles. NZVIs/SBA-15 composites offer a promising alternative material to remove heavy metals from groundwater.","SBA-15-incorporated nanoscale zero-valent iron particles for chromium(VI) removal from groundwater: Mechanism, effect of pH, humic acid and sustained reactivity Abs: Nanoscale zero-valent iron particles (NZVIs) were incorporated inside the channels of SBA-15 rods by a &quot;two solvents&quot; reduction technique and used to remove Cr(VI) from groundwater. The resulting NZVIs/SBA-15 composites before and after reaction were characterized by N2 adsorption/desorption, X-ray diffraction (XRD), transmission electron microscopy (TEM) and X-ray photoelectron spectroscopy (XPS). Results helped to propose the mechanism of Cr(VI) removal by NZVIs/SBA-15, where Cr(VI) in aqueous was firstly impregnated into the channels of the silica, then adsorbed on the surfaces of the incorporated NZVIs and reduced to Cr(III) directly in the inner pores of the silica. Corrosion products included Fe2O3, FeO(OH), Fe3O4 and Cr2FeO4. Batch experiments revealed that Cr(VI) removal decreased from 99.7% to 92.8% when the initial solution pH increased from 5.5 to 9.0, accompanied by the decrease of the kobs from 0.600 to 0.024min(-1). Humic acid (HA) had a little effect on the removal efficiency of Cr(VI) by NZVIs/SBA-15 but could decrease the reduction rate. The stable reduction of NZVIs/SBA-15 was observed within six cycles. NZVIs/SBA-15 composites offer a promising alternative material to remove heavy metals from groundwater."
2225062,N?me?ek et al. ,Nanoscale zero-valent iron application for in situ reduction of hexavalent chromium and its effects on indigenous microorganism populations,"Because of its high toxicity and mobility, hexavalent chromium is considered to be a high priority pollutant. This study was performed to carry out a pilot-scale in-situ remediation test in the saturated zone of a historically Cr(VI)-contaminated site using commercially available nanoscale zero-valent iron (nZVI). The site was monitored before and after the nZVI application by means of microbial cultivation tests, phospholipid fatty acid analysis (PLFA) and toxicological tests with Vibrio fischeri. Injection of nZVI resulted in a rapid decrease in the Cr(VI) and total Cr concentrations in the groundwater without any substantial effect on its chemical properties. The ecotoxicological test with V. fischeri did not indicate any negative changes in the toxicity of the groundwater following the application of nZVI and no significant changes were observed in cultivable psychrophilic bacteria densities and PLFA concentrations in the groundwater samples during the course of the remediation test. However, PLFA of soil samples revealed that the application of nZVI significantly stimulated the growth of Gram-positive bacteria. Principle component analysis (PCA) was applied to the PLFA results for the soil samples from the site in order to explain how Cr(VI) reduction and the presence of Fe influence the indigenous populations. The PCA results clearly indicated a negative correlation between the Cr concentrations and the biota before the application of nZVI and a significant positive correlation between bacteria and the concentration of Fe after the application of nZVI.","Nanoscale zero-valent iron application for in situ reduction of hexavalent chromium and its effects on indigenous microorganism populations Abs: Because of its high toxicity and mobility, hexavalent chromium is considered to be a high priority pollutant. This study was performed to carry out a pilot-scale in-situ remediation test in the saturated zone of a historically Cr(VI)-contaminated site using commercially available nanoscale zero-valent iron (nZVI). The site was monitored before and after the nZVI application by means of microbial cultivation tests, phospholipid fatty acid analysis (PLFA) and toxicological tests with Vibrio fischeri. Injection of nZVI resulted in a rapid decrease in the Cr(VI) and total Cr concentrations in the groundwater without any substantial effect on its chemical properties. The ecotoxicological test with V. fischeri did not indicate any negative changes in the toxicity of the groundwater following the application of nZVI and no significant changes were observed in cultivable psychrophilic bacteria densities and PLFA concentrations in the groundwater samples during the course of the remediation test. However, PLFA of soil samples revealed that the application of nZVI significantly stimulated the growth of Gram-positive bacteria. Principle component analysis (PCA) was applied to the PLFA results for the soil samples from the site in order to explain how Cr(VI) reduction and the presence of Fe influence the indigenous populations. The PCA results clearly indicated a negative correlation between the Cr concentrations and the biota before the application of nZVI and a significant positive correlation between bacteria and the concentration of Fe after the application of nZVI."
2225061,Tiersch et al. 2014,Artificial infection of chickens with Capillaria obsignata eggs embryonated in different media,"The present study investigated whether incubation media have an impact on infectivity of Capillaria obsignata eggs in chickens infected with gradually increasing doses. C. obsignata eggs collected from female worms were incubated either in formalin (0.5% or 2%) or in potassium dichromate 0.1% or in sulfuric acid 0.1N for three weeks (wk). One-day-old male chicks (N=92) were reared in a parasite-free environment, and infected with 0, 500, 1000 or 2000 eggs at an age of 3wk. Post-mortem parasitological examinations were performed on day 28p.i. Although all the infected birds harboured adult worms, their growth performance was not affected. Furthermore there was no significant interaction effect between incubation media and infection dose on worm establishment rates (P=0.080), while main effects of these two factors were significant (P&lt;0.05). The average number of adult worms found in birds infected with the eggs incubated in potassium dichromate were significantly lower (P&lt;0.001) than in formalin 0.5%, formalin 2% and sulfuric acid 0.1N. A higher (P&lt;0.05) percentage of larvae could establish themselves in the intestines when the birds were infected with 500 eggs (40.5%) instead of 2000 eggs (26.2%), indicating density dependent effects. It is concluded that formalin (particularly 0.5%), and sulfuric acid can successfully be used as incubation media for C. obsignata eggs, whereas potassium dichromate impairs subsequent infectivity of the eggs. Although effects of media on the infectivity of the eggs were confirmed to be fairly repeatable, no harmful effect of infection was quantified on the host animal performance with the infection doses up to 2000 eggs.","Artificial infection of chickens with Capillaria obsignata eggs embryonated in different media Abs: The present study investigated whether incubation media have an impact on infectivity of Capillaria obsignata eggs in chickens infected with gradually increasing doses. C. obsignata eggs collected from female worms were incubated either in formalin (0.5% or 2%) or in potassium dichromate 0.1% or in sulfuric acid 0.1N for three weeks (wk). One-day-old male chicks (N=92) were reared in a parasite-free environment, and infected with 0, 500, 1000 or 2000 eggs at an age of 3wk. Post-mortem parasitological examinations were performed on day 28p.i. Although all the infected birds harboured adult worms, their growth performance was not affected. Furthermore there was no significant interaction effect between incubation media and infection dose on worm establishment rates (P=0.080), while main effects of these two factors were significant (P&lt;0.05). The average number of adult worms found in birds infected with the eggs incubated in potassium dichromate were significantly lower (P&lt;0.001) than in formalin 0.5%, formalin 2% and sulfuric acid 0.1N. A higher (P&lt;0.05) percentage of larvae could establish themselves in the intestines when the birds were infected with 500 eggs (40.5%) instead of 2000 eggs (26.2%), indicating density dependent effects. It is concluded that formalin (particularly 0.5%), and sulfuric acid can successfully be used as incubation media for C. obsignata eggs, whereas potassium dichromate impairs subsequent infectivity of the eggs. Although effects of media on the infectivity of the eggs were confirmed to be fairly repeatable, no harmful effect of infection was quantified on the host animal performance with the infection doses up to 2000 eggs."
2225060,García-Rodríguez et al. 2013,Antigenotoxic and apoptotic activity of green tea polyphenol extracts on hexavalent chromium-induced DNA damage in peripheral blood of CD-1 mice: Analysis with differential acridine orange/ethidium bromide staining,"This study was conducted to investigate the modulating effects of green tea polyphenols on genotoxic damage and apoptotic activity induced by hexavalent chromium [Cr (VI)] in CD-1 mice. Animals were divided into the following groups: (i) injected with vehicle; (ii) treated with green tea polyphenols (30 mg/kg) via gavage; (iii) injected with CrO3 (20 mg/kg) intraperitoneally; (iv) treated with green tea polyphenols in addition to CrO3. Genotoxic damage was evaluated by examining micronucleated polychromatic erythrocytes (MN-PCEs) obtained from peripheral blood at 0, 24, 48, and 72 h after treatment. Induction of apoptosis and cell viability were assessed by differential acridine orange/ethidium bromide (AO/EB) staining. Treatment of green tea polyphenols led to no significant changes in the MN-PCEs. However, CrO3 treatment significantly increased MN-PCEs at 24 and 48 h after injection. Green tea polyphenols treatment prior to CrO3 injection led to a decrease in MN-PCEs compared to the group treated with CrO3 only. The average of apoptotic cells was increased at 48 h after treatment compared to control mice, suggesting that apoptosis could contribute to eliminate the DNA damaged cells induced by Cr (VI). Our findings support the proposed protective effects of green tea polyphenols against the genotoxic damage induced by Cr (VI).","Antigenotoxic and apoptotic activity of green tea polyphenol extracts on hexavalent chromium-induced DNA damage in peripheral blood of CD-1 mice: Analysis with differential acridine orange/ethidium bromide staining Abs: This study was conducted to investigate the modulating effects of green tea polyphenols on genotoxic damage and apoptotic activity induced by hexavalent chromium [Cr (VI)] in CD-1 mice. Animals were divided into the following groups: (i) injected with vehicle; (ii) treated with green tea polyphenols (30 mg/kg) via gavage; (iii) injected with CrO3 (20 mg/kg) intraperitoneally; (iv) treated with green tea polyphenols in addition to CrO3. Genotoxic damage was evaluated by examining micronucleated polychromatic erythrocytes (MN-PCEs) obtained from peripheral blood at 0, 24, 48, and 72 h after treatment. Induction of apoptosis and cell viability were assessed by differential acridine orange/ethidium bromide (AO/EB) staining. Treatment of green tea polyphenols led to no significant changes in the MN-PCEs. However, CrO3 treatment significantly increased MN-PCEs at 24 and 48 h after injection. Green tea polyphenols treatment prior to CrO3 injection led to a decrease in MN-PCEs compared to the group treated with CrO3 only. The average of apoptotic cells was increased at 48 h after treatment compared to control mice, suggesting that apoptosis could contribute to eliminate the DNA damaged cells induced by Cr (VI). Our findings support the proposed protective effects of green tea polyphenols against the genotoxic damage induced by Cr (VI)."
2225059,Haney et al. ,Development of an inhalation unit risk factor for hexavalent chromium,"A unit risk factor (URF) was developed for hexavalent chromium (CrVI). The URF is based on excess lung cancer mortality in two key epidemiological studies of chromate production workers. The Crump et al. (2003) study concerns the Painesville, OH worker cohort, while Gibb et al. (2000) regards the Baltimore, MD cohort. A supporting assessment was also performed for a cohort from four low-dose chromate plants (Leverkusen and Uerdingen, Germany, Corpus Christi, TX, Castle Hayne, NC). For the Crump et al. (2003) study, grouped observed and expected number of lung cancer mortalities along with cumulative CrVI exposures were used to obtain the maximum likelihood estimate and asymptotic variance of the slope (?) for the linear multiplicative relative risk model using Poisson regression modeling. For the Gibb et al. (2000) study, Cox proportional hazards modeling was performed with optimal exposure lag and adjusting for the effect of covariates (e.g., smoking) to estimate ? values. Life-table analyses were used to develop URFs for each of the two key studies, as well as for supporting and related studies. The two key study URFs were combined using weighting factors relevant to confidence to derive the final URF for CrVI of 2.3E-03 per ?gCrVI/m(3).","Development of an inhalation unit risk factor for hexavalent chromium Abs: A unit risk factor (URF) was developed for hexavalent chromium (CrVI). The URF is based on excess lung cancer mortality in two key epidemiological studies of chromate production workers. The Crump et al. (2003) study concerns the Painesville, OH worker cohort, while Gibb et al. (2000) regards the Baltimore, MD cohort. A supporting assessment was also performed for a cohort from four low-dose chromate plants (Leverkusen and Uerdingen, Germany, Corpus Christi, TX, Castle Hayne, NC). For the Crump et al. (2003) study, grouped observed and expected number of lung cancer mortalities along with cumulative CrVI exposures were used to obtain the maximum likelihood estimate and asymptotic variance of the slope (?) for the linear multiplicative relative risk model using Poisson regression modeling. For the Gibb et al. (2000) study, Cox proportional hazards modeling was performed with optimal exposure lag and adjusting for the effect of covariates (e.g., smoking) to estimate ? values. Life-table analyses were used to develop URFs for each of the two key studies, as well as for supporting and related studies. The two key study URFs were combined using weighting factors relevant to confidence to derive the final URF for CrVI of 2.3E-03 per ?gCrVI/m(3)."
2225058,Gu et al. 2013,[Evidence-based study of chromate exposed workers' health surveillance indexes],"<strong>OBJECTIVE: </strong>The health surveillance proposal for chromate exposed workers was provided and analyzed on the evidence-based study and then to be improved.<br /><br /><strong>METHOD: </strong>Firstly, the related literatures were searched about liver damage, micronuclei, urinary chromium and hexavalent chromium exposure in Evidence Based Medicine Reviews such as Cochran library, OVID Medline, Web of knowledge in December 2011; and then, these literatures were reviewed in according to inclusion and exclusion criterias; 22 articles totally were retrieved, evaluated and classified in according to the grading standard by Oxford Centre for Evidence-based Medicine.Finally, field epidemiological investigation was further adopted to confirm the efficiency and feasibility of this proposal, combined with cost-effectiveness analysis:the ratio of total cost divided survival years was used to express the cost-effectiveness.<br /><br /><strong>RESULT: </strong>Only the glutamic pyruvic transaminase test could not reflect liver damage caused by chromate exposure well; Unirary chromium correlated well with the index reflecting body damage caused by chromate exposure; Binucleated cells micronucleus index in peripheral blood lymphocyte could reflect the genetic damage caused by chromate exposure. As for health economic evaluation of chromate lung cancer, the value of cost/effectiveness was ¥42 321.61 per year that was far below the value of common people (¥252 868.97 per year) .<br /><br /><strong>CONCLUSION: </strong>It was suggested that serum glutamic pyruvic transaminase test should be replaced by liver function test, urinary chromium should be classified as a compulsory index and binucleated cells micronucleus index in peripheral blood lymphocyte should be supplied as a recommended index.","[Evidence-based study of chromate exposed workers' health surveillance indexes] Abs: <strong>OBJECTIVE: </strong>The health surveillance proposal for chromate exposed workers was provided and analyzed on the evidence-based study and then to be improved.<br /><br /><strong>METHOD: </strong>Firstly, the related literatures were searched about liver damage, micronuclei, urinary chromium and hexavalent chromium exposure in Evidence Based Medicine Reviews such as Cochran library, OVID Medline, Web of knowledge in December 2011; and then, these literatures were reviewed in according to inclusion and exclusion criterias; 22 articles totally were retrieved, evaluated and classified in according to the grading standard by Oxford Centre for Evidence-based Medicine.Finally, field epidemiological investigation was further adopted to confirm the efficiency and feasibility of this proposal, combined with cost-effectiveness analysis:the ratio of total cost divided survival years was used to express the cost-effectiveness.<br /><br /><strong>RESULT: </strong>Only the glutamic pyruvic transaminase test could not reflect liver damage caused by chromate exposure well; Unirary chromium correlated well with the index reflecting body damage caused by chromate exposure; Binucleated cells micronucleus index in peripheral blood lymphocyte could reflect the genetic damage caused by chromate exposure. As for health economic evaluation of chromate lung cancer, the value of cost/effectiveness was ¥42 321.61 per year that was far below the value of common people (¥252 868.97 per year) .<br /><br /><strong>CONCLUSION: </strong>It was suggested that serum glutamic pyruvic transaminase test should be replaced by liver function test, urinary chromium should be classified as a compulsory index and binucleated cells micronucleus index in peripheral blood lymphocyte should be supplied as a recommended index."
2225057,Mishra and  Mohanty ,"Effect of acute hexavalent chromium exposure on pituitary-thyroid axis of a freshwater fish, Channa punctatus (Bloch)","Acute exposure to hexavalent chromium (10 mg L(-1) , 20 mg L(-1) , and 40 mg L(-1) potassium dichromate for 96 h) dose-dependently affected the pituitary-thyroid axis of teleost, Channa punctatus. Significant hypertrophy of the thyroid follicle was observed in 20 mg L(-1) and 40 mg L(-1) groups; the follicular epithelium was however hypertrophied only in 40 mg L(-1) group. The colloid depletion in the lumen of thyroid follicle was evident in 20 mg L(-1) and 40 mg L(-1) groups. Serum thyroid hormones (thyroxine/T4 and triiodothyronine/T3) level increased significantly at both the higher doses. Increased immunointensity and significant hypertrophy of the pituitary thyrotrophs (anti TSH?-immunoreactive cells) was observed in both 20 mg L(-1) and 40 mg L(-1) chromium-exposed fish. The increased thyroid hormones secretion observed in this study might be an adaptive response of the pituitary-thyroid axis under acute chromium-induced stress condition to maintain homeostasis. The long-term Cr(VI) exposures, however, may lead to attenuation/exhaustion of the pituitary-thyroid axis and pose serious threat to fish health and affect their population. © 2013 Wiley Periodicals, Inc. Environ Toxicol, 2013.","Effect of acute hexavalent chromium exposure on pituitary-thyroid axis of a freshwater fish, Channa punctatus (Bloch) Abs: Acute exposure to hexavalent chromium (10 mg L(-1) , 20 mg L(-1) , and 40 mg L(-1) potassium dichromate for 96 h) dose-dependently affected the pituitary-thyroid axis of teleost, Channa punctatus. Significant hypertrophy of the thyroid follicle was observed in 20 mg L(-1) and 40 mg L(-1) groups; the follicular epithelium was however hypertrophied only in 40 mg L(-1) group. The colloid depletion in the lumen of thyroid follicle was evident in 20 mg L(-1) and 40 mg L(-1) groups. Serum thyroid hormones (thyroxine/T4 and triiodothyronine/T3) level increased significantly at both the higher doses. Increased immunointensity and significant hypertrophy of the pituitary thyrotrophs (anti TSH?-immunoreactive cells) was observed in both 20 mg L(-1) and 40 mg L(-1) chromium-exposed fish. The increased thyroid hormones secretion observed in this study might be an adaptive response of the pituitary-thyroid axis under acute chromium-induced stress condition to maintain homeostasis. The long-term Cr(VI) exposures, however, may lead to attenuation/exhaustion of the pituitary-thyroid axis and pose serious threat to fish health and affect their population. © 2013 Wiley Periodicals, Inc. Environ Toxicol, 2013."
2225056,Castro et al. 2014,"Acute Toxicity by Water Containing Hexavalent or Trivalent Chromium in Native Brazilian Fish, Piaractus mesopotamicus: Anatomopathological Alterations and Mortality","This study evaluated the toxicity of hexavalent and trivalent compounds of chromium to the pacu, Piaractus mesopotamicus, in acute exposures of 96 h through mortality and histopathological responses. Hexavalent potassium dichromate was more toxic than trivalent compounds of chromium chloride, chromium oxide and chromium carbochelate. Sufficient mortalities occurred only with potassium dichromate to yield an LC50 value at 124.2 mg L(-1). Hexavalent chromium caused reversible and irreversible lesions, which may affect organ functionality. Histopathological evaluation showed that trivalent chromium caused lesions of lower severity. Pacu subjected to different concentrations of chromium carbochelate showed no histopathological changes in the kidneys, liver, skin and gills, being similar to those of the control fish. Among the three sources of Cr(3+), only chromium chloride at 200 mg L(-1) resulted in mortality, which reached 100 % within the first 18 h. These findings confirm that trivalent chromium, when administered within recommended levels, may be used safely in aquaculture.","Acute Toxicity by Water Containing Hexavalent or Trivalent Chromium in Native Brazilian Fish, Piaractus mesopotamicus: Anatomopathological Alterations and Mortality Abs: This study evaluated the toxicity of hexavalent and trivalent compounds of chromium to the pacu, Piaractus mesopotamicus, in acute exposures of 96 h through mortality and histopathological responses. Hexavalent potassium dichromate was more toxic than trivalent compounds of chromium chloride, chromium oxide and chromium carbochelate. Sufficient mortalities occurred only with potassium dichromate to yield an LC50 value at 124.2 mg L(-1). Hexavalent chromium caused reversible and irreversible lesions, which may affect organ functionality. Histopathological evaluation showed that trivalent chromium caused lesions of lower severity. Pacu subjected to different concentrations of chromium carbochelate showed no histopathological changes in the kidneys, liver, skin and gills, being similar to those of the control fish. Among the three sources of Cr(3+), only chromium chloride at 200 mg L(-1) resulted in mortality, which reached 100 % within the first 18 h. These findings confirm that trivalent chromium, when administered within recommended levels, may be used safely in aquaculture."
2225055,Torkmahalleh et al. 2013,Improved atmospheric sampling of hexavalent chromium,"Hexavalent chromium (Cr(VI)) and trivalent chromium (Cr(III)) are the primary chromium oxidation states found in ambient atmospheric particulate matter. While Cr(III) is relatively nontoxic, Cr(VI) is toxic and exposure to Cr(VI) may lead to cancer, nasal damage, asthma, bronchitis, and pneumonitis. Accurate measurement of the ambient Cr(VI) concentrations is an environmental challenge since Cr(VI) can be reduced to Cr(III) and vice versa during sampling. In the present study, a new Cr(VI) sampler (Clarkson sampler) was designed, constructed, and field tested to improve the sampling of Cr(VI) in ambient air. The new Clarkson Cr(VI) sampler was based on the concept that deliquescence during sampling leads to aqueous phase reactions. Thus, the relative humidity of the sampled air was reduced below the deliquescence relative humidity (DRH) of the ambient particles. The new sampler was operated to collect total suspended particles (TSP), and compared side-by-side with the current National Air Toxics Trends Stations (NATTS) Cr(VI) sampler that is utilized in the US. Environmental Protection Agency (EPA) air toxics monitoring program. Side-by-side field testing of the samplers occurred in Elizabeth, NJ during the winter and summer of 2012. The average recovery values of Cr(VI) spikes after 24-hr sampling intervals during summer and winter sampling were 57 and 72%, respectively, for the Clarkson sampler while the corresponding average values for NATTS samplers were 46% for both summer and winter sampling, respectively. Preventing the ambient aerosol collected on the filters from deliquescing is a key to improving the sampling of Cr(VI).","Improved atmospheric sampling of hexavalent chromium Abs: Hexavalent chromium (Cr(VI)) and trivalent chromium (Cr(III)) are the primary chromium oxidation states found in ambient atmospheric particulate matter. While Cr(III) is relatively nontoxic, Cr(VI) is toxic and exposure to Cr(VI) may lead to cancer, nasal damage, asthma, bronchitis, and pneumonitis. Accurate measurement of the ambient Cr(VI) concentrations is an environmental challenge since Cr(VI) can be reduced to Cr(III) and vice versa during sampling. In the present study, a new Cr(VI) sampler (Clarkson sampler) was designed, constructed, and field tested to improve the sampling of Cr(VI) in ambient air. The new Clarkson Cr(VI) sampler was based on the concept that deliquescence during sampling leads to aqueous phase reactions. Thus, the relative humidity of the sampled air was reduced below the deliquescence relative humidity (DRH) of the ambient particles. The new sampler was operated to collect total suspended particles (TSP), and compared side-by-side with the current National Air Toxics Trends Stations (NATTS) Cr(VI) sampler that is utilized in the US. Environmental Protection Agency (EPA) air toxics monitoring program. Side-by-side field testing of the samplers occurred in Elizabeth, NJ during the winter and summer of 2012. The average recovery values of Cr(VI) spikes after 24-hr sampling intervals during summer and winter sampling were 57 and 72%, respectively, for the Clarkson sampler while the corresponding average values for NATTS samplers were 46% for both summer and winter sampling, respectively. Preventing the ambient aerosol collected on the filters from deliquescing is a key to improving the sampling of Cr(VI)."
2225054,Thyssen et al. 2014,Hexavalent chromium in leather is now regulated in European Union member states to limit chromium allergy and dermatitis,,Hexavalent chromium in leather is now regulated in European Union member states to limit chromium allergy and dermatitis Abs: 
2225053,Mukherjee et al. ,Best combination of promoter and micellar catalyst for the rapid conversion of sorbitol to glucose,"Kinetic data for oxidation of D-sorbitol to glucose by hexavalent chromium in aqueous medium and aqueous surfactant medium (SDS, TX-100) have been reported. Effect of promoter such as PA, bipy and phenanthroline on the reaction has been investigated. The reaction is performed under pseudo first order condition with an excess of substrate over the oxidant. The reaction is first order with respect to substrate and oxidant. The micelles have a catalytic effect on the reaction. Combination of phen and TX-100 produces almost twelve times increase in rate of oxidation.","Best combination of promoter and micellar catalyst for the rapid conversion of sorbitol to glucose Abs: Kinetic data for oxidation of D-sorbitol to glucose by hexavalent chromium in aqueous medium and aqueous surfactant medium (SDS, TX-100) have been reported. Effect of promoter such as PA, bipy and phenanthroline on the reaction has been investigated. The reaction is performed under pseudo first order condition with an excess of substrate over the oxidant. The reaction is first order with respect to substrate and oxidant. The micelles have a catalytic effect on the reaction. Combination of phen and TX-100 produces almost twelve times increase in rate of oxidation."
2225052,Huang et al. ,Comparative Studies of Tri- and Hexavalent Chromium Cytotoxicity and Their Effects on Oxidative State of Saccharomyces cerevisiae Cells,"Chromium is a significant mutagen and carcinogen in environment. We compared the effects of tri- and hexavalent chromium on cytotoxicity and oxidative stress in yeast. Cell growth was inhibited by Cr(3+) or Cr(6+), and Cr(6+) significantly increased the lethal rate compared with Cr(3+). Both Cr(3+) and Cr(6+) can enter into the yeast cells. The percent of propidium iodide permeable cells treated with Cr(3+) is almost five times as that treated with the same concentration of Cr(6+). Levels of TBARS, O2 (-), and carbonyl protein were significantly increased in both Cr(6+)- and Cr(3+)-treated cells in a concentration- and time-dependent manner. Moreover, the accumulation of these stress markers in Cr(6+)-treated cells was over the Cr(3+)-treated ones. The decreased GSH level and increased activity of GPx were observed after 300 ?M Cr(6+)-exposure compared with the untreated control, whereas there was no other change of GSH content in cells treated with Cr(3+) even at very high concentration. Exposure to both Cr(3+) and Cr(6+) resulted in the decrease of activities of SOD and catalase. Furthermore, the effect of Cr(6+) is stronger than that of Cr(3+). Null mutation sensitivity assay demonstrated that the gsh1 mutant was sensitive to Cr(6+) other than Cr(3+), the apn1 mutant is more sensitive to Cr(6+) than Cr(3+), and the rad1 mutant is sensitive to both Cr(6+) and Cr(3+). Therefore, Cr(3+) can be concluded to inhibit cell growth probably due to the damage of plasma membrane integrality in yeast. Although both tri- and hexavalent chromium can induce cytotoxicity and oxidative stress, the action mode of Cr(3+) is different from that of Cr(6+), and serious membrane damage caused by Cr(3+) is not the direct consequence of the increase of lipid peroxidation.","Comparative Studies of Tri- and Hexavalent Chromium Cytotoxicity and Their Effects on Oxidative State of Saccharomyces cerevisiae Cells Abs: Chromium is a significant mutagen and carcinogen in environment. We compared the effects of tri- and hexavalent chromium on cytotoxicity and oxidative stress in yeast. Cell growth was inhibited by Cr(3+) or Cr(6+), and Cr(6+) significantly increased the lethal rate compared with Cr(3+). Both Cr(3+) and Cr(6+) can enter into the yeast cells. The percent of propidium iodide permeable cells treated with Cr(3+) is almost five times as that treated with the same concentration of Cr(6+). Levels of TBARS, O2 (-), and carbonyl protein were significantly increased in both Cr(6+)- and Cr(3+)-treated cells in a concentration- and time-dependent manner. Moreover, the accumulation of these stress markers in Cr(6+)-treated cells was over the Cr(3+)-treated ones. The decreased GSH level and increased activity of GPx were observed after 300 ?M Cr(6+)-exposure compared with the untreated control, whereas there was no other change of GSH content in cells treated with Cr(3+) even at very high concentration. Exposure to both Cr(3+) and Cr(6+) resulted in the decrease of activities of SOD and catalase. Furthermore, the effect of Cr(6+) is stronger than that of Cr(3+). Null mutation sensitivity assay demonstrated that the gsh1 mutant was sensitive to Cr(6+) other than Cr(3+), the apn1 mutant is more sensitive to Cr(6+) than Cr(3+), and the rad1 mutant is sensitive to both Cr(6+) and Cr(3+). Therefore, Cr(3+) can be concluded to inhibit cell growth probably due to the damage of plasma membrane integrality in yeast. Although both tri- and hexavalent chromium can induce cytotoxicity and oxidative stress, the action mode of Cr(3+) is different from that of Cr(6+), and serious membrane damage caused by Cr(3+) is not the direct consequence of the increase of lipid peroxidation."
2225051,Zheng et al. 2013,On-Off-On Fluorescent Carbon Dot Nanosensor for Recognition of Chromium(VI) and Ascorbic Acid Based on the Inner Filter Effect,"Chromium(VI) [Cr(VI)] is considered as a severe environmental pollutant, due to its highly toxic and carcinogenic properties. Therefore, low cost, highly sensitive sensors for the determination of Cr(VI) are highly demanded. It is well-known that highly luminescent carbon dots (CDs) have been successfully applied as fluorescent nanosensors for pH, ions, and molecular substances. In the present work, we have demonstrated an on-off fluorescent CD probe for detecting Cr(VI) based on the inner filter effect (IFE) because the absorption bands of Cr(IV) fully covered the emission and excitation bands of CDs. This CD-based nanosensor provides obvious advantages of simplicity, convenience, rapid response, high selectivity, and sensitivity, which have potential application for the detection of Cr(VI) in the environmental industry. In addition, because Cr(VI) can be reduced to low valent chromium species easily by reductant, resulting in the elimination of the IFE and recovery of CD fluorescence, the CD-Cr(VI) mixture could behave as an off-on type fluorescent probe for reductant. We employed ascorbic acid (AA) as an example molecule to demonstrate this off-on type fluorescent probe.","On-Off-On Fluorescent Carbon Dot Nanosensor for Recognition of Chromium(VI) and Ascorbic Acid Based on the Inner Filter Effect Abs: Chromium(VI) [Cr(VI)] is considered as a severe environmental pollutant, due to its highly toxic and carcinogenic properties. Therefore, low cost, highly sensitive sensors for the determination of Cr(VI) are highly demanded. It is well-known that highly luminescent carbon dots (CDs) have been successfully applied as fluorescent nanosensors for pH, ions, and molecular substances. In the present work, we have demonstrated an on-off fluorescent CD probe for detecting Cr(VI) based on the inner filter effect (IFE) because the absorption bands of Cr(IV) fully covered the emission and excitation bands of CDs. This CD-based nanosensor provides obvious advantages of simplicity, convenience, rapid response, high selectivity, and sensitivity, which have potential application for the detection of Cr(VI) in the environmental industry. In addition, because Cr(VI) can be reduced to low valent chromium species easily by reductant, resulting in the elimination of the IFE and recovery of CD fluorescence, the CD-Cr(VI) mixture could behave as an off-on type fluorescent probe for reductant. We employed ascorbic acid (AA) as an example molecule to demonstrate this off-on type fluorescent probe."
2225050,Li et al. 2013,A novel Au-Ag-Pt three-electrode microchip sensing platform for chromium(VI) determination,"A simple, rapid and portable electrochemical microchip sensing platform has been successfully constructed for chromium(VI) determination. Gold-silver-platinum (Au-Ag-Pt) three-material electrodes (gold as working electrode, silver as reference electrode and platinum as counter electrode) were integrated on one poly(methyl methacrylate) (PMMA) substrate by polymer compatible photolithography process. The three-electrode microchip sensing platform was used for Cr(VI) determination for the first time, and exhibited high sensitivity and good reproducibility. A wide linear range from 2 to 200 ?M with a good linear correlation (R(2)=0.998) was obtained, and the detection limit was 0.9 ?M. In addition, the practical analytical application of the sensing micro-platform was assessed by determination of Cr(VI) in real water samples with satisfactory results. Armed with the remarkable advantages, such as ease of use, low analyte consumption, inexpensive cost and fast response time, the microchip sensing platform may hold great potential for the high-throughput and in-field environmental monitoring Cr(VI) pollutant.","A novel Au-Ag-Pt three-electrode microchip sensing platform for chromium(VI) determination Abs: A simple, rapid and portable electrochemical microchip sensing platform has been successfully constructed for chromium(VI) determination. Gold-silver-platinum (Au-Ag-Pt) three-material electrodes (gold as working electrode, silver as reference electrode and platinum as counter electrode) were integrated on one poly(methyl methacrylate) (PMMA) substrate by polymer compatible photolithography process. The three-electrode microchip sensing platform was used for Cr(VI) determination for the first time, and exhibited high sensitivity and good reproducibility. A wide linear range from 2 to 200 ?M with a good linear correlation (R(2)=0.998) was obtained, and the detection limit was 0.9 ?M. In addition, the practical analytical application of the sensing micro-platform was assessed by determination of Cr(VI) in real water samples with satisfactory results. Armed with the remarkable advantages, such as ease of use, low analyte consumption, inexpensive cost and fast response time, the microchip sensing platform may hold great potential for the high-throughput and in-field environmental monitoring Cr(VI) pollutant."
2225049,Sadek ,Chemotherapeutic efficacy of an ethanolic Moringa oleifera leaf extract against chromium-induced testicular toxicity in rats,"This study was conducted to determine the mechanism underlying the chemotherapeutic efficacy of an ethanolic Moringa oleifera leaf extract (MOLEE) against chromium-induced impairments of rat testes using biochemical methods. Twenty male Wistar rats were divided into four groups of five animals each. Group I (control), group II injected potassium dichromate (8 mg kg(-1) ) i.p., group III gastrogavaged MOLEE (500 mg kg(-1) ) p.o. and group IV received (potassium dichromate plus MOLEE) by the same doses for 60 days. After the blood samples were collected, the animals were sacrificed to determine the testicular antioxidant status and sperm parameters. The chromium-treated group exhibited a significant decrease in testicular antioxidant enzymatic activities, local immunity and sperm parameters as well as an increase in inflammatory markers when compared with the control and MOLEE-treated group. However, concurrent administration of chromium and MOLEE significantly ameliorated the chromium effects on the sperm parameters, local immunity, inflammatory markers and antioxidant enzymatic activities compared with rats exposed to chromium alone. This study concludes that chronic exposure to chromium produces clear testicular toxicity, which can either be prevented or at least decreased by concomitant administration of MOLEE. Interestingly, the metal ion chelation could attribute partly the antioxidant activities of MOLEE.","Chemotherapeutic efficacy of an ethanolic Moringa oleifera leaf extract against chromium-induced testicular toxicity in rats Abs: This study was conducted to determine the mechanism underlying the chemotherapeutic efficacy of an ethanolic Moringa oleifera leaf extract (MOLEE) against chromium-induced impairments of rat testes using biochemical methods. Twenty male Wistar rats were divided into four groups of five animals each. Group I (control), group II injected potassium dichromate (8 mg kg(-1) ) i.p., group III gastrogavaged MOLEE (500 mg kg(-1) ) p.o. and group IV received (potassium dichromate plus MOLEE) by the same doses for 60 days. After the blood samples were collected, the animals were sacrificed to determine the testicular antioxidant status and sperm parameters. The chromium-treated group exhibited a significant decrease in testicular antioxidant enzymatic activities, local immunity and sperm parameters as well as an increase in inflammatory markers when compared with the control and MOLEE-treated group. However, concurrent administration of chromium and MOLEE significantly ameliorated the chromium effects on the sperm parameters, local immunity, inflammatory markers and antioxidant enzymatic activities compared with rats exposed to chromium alone. This study concludes that chronic exposure to chromium produces clear testicular toxicity, which can either be prevented or at least decreased by concomitant administration of MOLEE. Interestingly, the metal ion chelation could attribute partly the antioxidant activities of MOLEE."
2225048,Sarkar et al. 2013,Manganese(II)-catalyzed and clay-minerals-mediated reduction of chromium(VI) by citrate,"Unlike lower valent iron (Fe), the potential role of lower valent manganese (Mn) in the reduction of hexavalent chromium (Cr(VI)) in soil is poorly documented. In this study, we report that citrate along with Mn(II) and clay minerals (montmorillonite and kaolinite) reduce Cr(VI) both in aqueous phase and in the presence of dissolved organic carbon (SDOC) extracted from a forest soil. The reduction was favorable at acidic pH (up to pH 5) and followed the pseudo-first-order kinetic model. The citrate (10 mM) + Mn(II) (182.02 ?M) + clay minerals (3% w/v) system in SDOC accounted for complete reduction of Cr(VI) (192.32 ?M) in about 72 h at pH 4.9. In this system, citrate was the reductant, Mn(II) was a catalyst, and the clay minerals acted as an accelerator for both the reductant and catalyst. The clay minerals also serve as a sink for Cr(III). This study reveals the underlying mechanism of the Mn(II)-induced reduction of Cr(VI) by organic ligand in the presence of clay minerals under certain environmental conditions.","Manganese(II)-catalyzed and clay-minerals-mediated reduction of chromium(VI) by citrate Abs: Unlike lower valent iron (Fe), the potential role of lower valent manganese (Mn) in the reduction of hexavalent chromium (Cr(VI)) in soil is poorly documented. In this study, we report that citrate along with Mn(II) and clay minerals (montmorillonite and kaolinite) reduce Cr(VI) both in aqueous phase and in the presence of dissolved organic carbon (SDOC) extracted from a forest soil. The reduction was favorable at acidic pH (up to pH 5) and followed the pseudo-first-order kinetic model. The citrate (10 mM) + Mn(II) (182.02 ?M) + clay minerals (3% w/v) system in SDOC accounted for complete reduction of Cr(VI) (192.32 ?M) in about 72 h at pH 4.9. In this system, citrate was the reductant, Mn(II) was a catalyst, and the clay minerals acted as an accelerator for both the reductant and catalyst. The clay minerals also serve as a sink for Cr(III). This study reveals the underlying mechanism of the Mn(II)-induced reduction of Cr(VI) by organic ligand in the presence of clay minerals under certain environmental conditions."
2225047,Tahri Joutey et al. ,Hexavalent chromium removal by a novel Serratia proteamaculans isolated from the bank of Sebou River (Morocco),"The novel Serratia proteamaculans isolated from a chromium-contaminated site was tolerant to a concentration of 500 mg Cr(VI)/l. The optimum pH and temperature for reduction of Cr(VI) by S. proteamaculans were found to be 7.0 and 30 °C, respectively. The Cr(VI) reduction rate decreased with the increase in Cr(VI) concentration from 100 to 400 mg/l, suggesting the enzymatic chromium reduction. Resting and permeabilised cell assays provided the better evidence that chromate reduction in S. proteamaculans is enzymatic. Reduction by cell-free filtrate shows no extracellular chromate-reducing activity, revealing that this activity may be associated to membrane fraction and/or cytosolic fraction. Assays conducted with cytosolic and particulate fraction of S. proteamaculans confirmed the role of membrane-bound proteins in Cr(VI) reduction. Furthermore, chromium reduced by heat-treated cells suggests that membrane-associated chromate reductase activity of S. proteamaculans is preceded by its adsorption on the cell surface.","Hexavalent chromium removal by a novel Serratia proteamaculans isolated from the bank of Sebou River (Morocco) Abs: The novel Serratia proteamaculans isolated from a chromium-contaminated site was tolerant to a concentration of 500 mg Cr(VI)/l. The optimum pH and temperature for reduction of Cr(VI) by S. proteamaculans were found to be 7.0 and 30 °C, respectively. The Cr(VI) reduction rate decreased with the increase in Cr(VI) concentration from 100 to 400 mg/l, suggesting the enzymatic chromium reduction. Resting and permeabilised cell assays provided the better evidence that chromate reduction in S. proteamaculans is enzymatic. Reduction by cell-free filtrate shows no extracellular chromate-reducing activity, revealing that this activity may be associated to membrane fraction and/or cytosolic fraction. Assays conducted with cytosolic and particulate fraction of S. proteamaculans confirmed the role of membrane-bound proteins in Cr(VI) reduction. Furthermore, chromium reduced by heat-treated cells suggests that membrane-associated chromate reductase activity of S. proteamaculans is preceded by its adsorption on the cell surface."
2225046,Jin et al. 2014,Sensitive and selective electrochemical detection of chromium(VI) based on gold nanoparticle-decorated titania nanotube arrays,"Owing to the severe toxicity and mobility of Cr(VI) in biological and environmental systems, it is of great importance to develop convenient and reliable methods for its detection. Here we report on a facile and effective electrochemical technique for monitoring Cr(VI) concentrations based on the utilization of Au nanoparticle-decorated titania nanotubes (TiO2NTs) grown on a titanium substrate. It was found that the electrochemical reduction of Cr(VI) at the Ti/TiO2NT/Au electrode exhibited an almost 23 fold improvement in activity as compared to a polycrystalline gold electrode, due to its nanoparticle/nanotubular heterojunction infrastructure. As a result, the Ti/TiO2NT/Au electrode demonstrated a wide linear concentration range from 0.10 ?M to 105 ?M, a low detection limit of 0.03 ?M, and a high sensitivity of 6.91 ?A ?M(-1) Cr(VI) via amperometry, satisfying the detection requirements of the World Health Organization (WHO). Moreover, the Ti/TiO2NT/Au electrode exhibited good resistance against interference from coexisting Cr(III) and other metal ions, and excellent recovery for Cr(VI) detection in both tap and lake water samples. These attributes suggest that this hybrid sensor has strong potential in applications for the selective detection of Cr(VI).","Sensitive and selective electrochemical detection of chromium(VI) based on gold nanoparticle-decorated titania nanotube arrays Abs: Owing to the severe toxicity and mobility of Cr(VI) in biological and environmental systems, it is of great importance to develop convenient and reliable methods for its detection. Here we report on a facile and effective electrochemical technique for monitoring Cr(VI) concentrations based on the utilization of Au nanoparticle-decorated titania nanotubes (TiO2NTs) grown on a titanium substrate. It was found that the electrochemical reduction of Cr(VI) at the Ti/TiO2NT/Au electrode exhibited an almost 23 fold improvement in activity as compared to a polycrystalline gold electrode, due to its nanoparticle/nanotubular heterojunction infrastructure. As a result, the Ti/TiO2NT/Au electrode demonstrated a wide linear concentration range from 0.10 ?M to 105 ?M, a low detection limit of 0.03 ?M, and a high sensitivity of 6.91 ?A ?M(-1) Cr(VI) via amperometry, satisfying the detection requirements of the World Health Organization (WHO). Moreover, the Ti/TiO2NT/Au electrode exhibited good resistance against interference from coexisting Cr(III) and other metal ions, and excellent recovery for Cr(VI) detection in both tap and lake water samples. These attributes suggest that this hybrid sensor has strong potential in applications for the selective detection of Cr(VI)."
2225045,Trujillo et al. 2013,Renoprotective effect of the antioxidant curcumin: Recent findings,"For years, there have been studies based on the use of natural compounds plant-derived as potential therapeutic agents for various diseases in humans. Curcumin is a phenolic compound extracted from Curcuma longa rhizome commonly used in Asia as a spice, pigment and additive. In traditional medicine of India and China, curcumin is considered as a therapeutic agent used in several foods. Numerous studies have shown that curcumin has broad biological functions particularly antioxidant and antiinflammatory. In fact, it has been established that curcumin is a bifunctional antioxidant; it exerts antioxidant activity in a direct and an indirect way by scavenging reactive oxygen species and inducing an antioxidant response, respectively. The renoprotective effect of curcumin has been evaluated in several experimental models including diabetic nephropathy, chronic renal failure, ischemia and reperfusion and nephrotoxicity induced by compounds such as gentamicin, adriamycin, chloroquine, iron nitrilotriacetate, sodium fluoride, hexavalent chromium and cisplatin. It has been shown recently in a model of chronic renal failure that curcumin exerts a therapeutic effect; in fact it reverts not only systemic alterations but also glomerular hemodynamic changes. Another recent finding shows that the renoprotective effect of curcumin is associated to preservation of function and redox balance of mitochondria. Taking together, these studies attribute the protective effect of curcumin in the kidney to the induction of the master regulator of antioxidant response nuclear factor erythroid-derived 2 (Nrf2), inhibition of mitochondrial dysfunction, attenuation of inflammatory response, preservation of antioxidant enzymes and prevention of oxidative stress. The information presented in this paper identifies curcumin as a promising renoprotective molecule against renal injury.","Renoprotective effect of the antioxidant curcumin: Recent findings Abs: For years, there have been studies based on the use of natural compounds plant-derived as potential therapeutic agents for various diseases in humans. Curcumin is a phenolic compound extracted from Curcuma longa rhizome commonly used in Asia as a spice, pigment and additive. In traditional medicine of India and China, curcumin is considered as a therapeutic agent used in several foods. Numerous studies have shown that curcumin has broad biological functions particularly antioxidant and antiinflammatory. In fact, it has been established that curcumin is a bifunctional antioxidant; it exerts antioxidant activity in a direct and an indirect way by scavenging reactive oxygen species and inducing an antioxidant response, respectively. The renoprotective effect of curcumin has been evaluated in several experimental models including diabetic nephropathy, chronic renal failure, ischemia and reperfusion and nephrotoxicity induced by compounds such as gentamicin, adriamycin, chloroquine, iron nitrilotriacetate, sodium fluoride, hexavalent chromium and cisplatin. It has been shown recently in a model of chronic renal failure that curcumin exerts a therapeutic effect; in fact it reverts not only systemic alterations but also glomerular hemodynamic changes. Another recent finding shows that the renoprotective effect of curcumin is associated to preservation of function and redox balance of mitochondria. Taking together, these studies attribute the protective effect of curcumin in the kidney to the induction of the master regulator of antioxidant response nuclear factor erythroid-derived 2 (Nrf2), inhibition of mitochondrial dysfunction, attenuation of inflammatory response, preservation of antioxidant enzymes and prevention of oxidative stress. The information presented in this paper identifies curcumin as a promising renoprotective molecule against renal injury."
2225044,Viti et al. ,Molecular mechanisms of Cr(VI) resistance in bacteria and fungi,"Hexavalent chromium [Cr(VI)] contamination is one of the main problems of environmental protection because the Cr(VI) is a hazard to human health. The Cr(VI) form is highly toxic, mutagenic, and carcinogenic, and it spreads widely beyond the site of initial contamination because of its mobility. Cr(VI), crossing the cellular membrane via the sulfate uptake pathway, generates active intermediates Cr(V) and/or Cr(IV), free radicals, and Cr(III) as the final product. Cr(III) affects DNA replication, causes mutagenesis, and alters the structure and activity of enzymes, reacting with their carboxyl and thiol groups. To persist in Cr(VI)-contaminated environments, microorganisms must have efficient systems to neutralize the negative effects of this form of chromium. The systems involve detoxification or repair strategies such as Cr(VI) efflux pumps, Cr(VI) reduction to Cr(III), and activation of enzymes involved in the ROS detoxifying processes, repair of DNA lesions, sulfur metabolism, and iron homeostasis. This review provides an overview of the processes involved in bacterial and fungal Cr(VI) resistance that have been identified through 'omics' studies. A comparative analysis of the described molecular mechanisms is offered and compared with the cellular evidences obtained using classical microbiological approaches.","Molecular mechanisms of Cr(VI) resistance in bacteria and fungi Abs: Hexavalent chromium [Cr(VI)] contamination is one of the main problems of environmental protection because the Cr(VI) is a hazard to human health. The Cr(VI) form is highly toxic, mutagenic, and carcinogenic, and it spreads widely beyond the site of initial contamination because of its mobility. Cr(VI), crossing the cellular membrane via the sulfate uptake pathway, generates active intermediates Cr(V) and/or Cr(IV), free radicals, and Cr(III) as the final product. Cr(III) affects DNA replication, causes mutagenesis, and alters the structure and activity of enzymes, reacting with their carboxyl and thiol groups. To persist in Cr(VI)-contaminated environments, microorganisms must have efficient systems to neutralize the negative effects of this form of chromium. The systems involve detoxification or repair strategies such as Cr(VI) efflux pumps, Cr(VI) reduction to Cr(III), and activation of enzymes involved in the ROS detoxifying processes, repair of DNA lesions, sulfur metabolism, and iron homeostasis. This review provides an overview of the processes involved in bacterial and fungal Cr(VI) resistance that have been identified through 'omics' studies. A comparative analysis of the described molecular mechanisms is offered and compared with the cellular evidences obtained using classical microbiological approaches."
2225043,Baig et al. 2013,Ultratrace Determination of Cr(VI) and Pb(II) by Microsample Injection System Flame Atomic Spectroscopy in Drinking Water and Treated and Untreated Industrial Effluents,"Simple and robust analytical procedures were developed for hexavalent chromium (Cr(VI)) and lead (Pb(II)) by dispersive liquid-liquid microextraction (DLLME) using microsample injection system coupled with flame atomic absorption spectrophotometry (MIS-FAAS). For the current study, ammonium pyrrolidine dithiocarbamate (APDC), carbon tetrachloride, and ethanol were used as chelating agent, extraction solvent, and disperser solvent, respectively. The effective variables of developed method have been optimized and studied in detail. The limit of detection of Cr(VI) and Pb(II) were 0.037 and 0.054?µg/L, respectively. The enrichment factors in both cases were 400 with 40?mL of initial volumes. The relative standard deviations (RSDs, n = 6) were &lt;4%. The applicability and the accuracy of DLLME were estimated by the analysis of Cr(VI) and Pb(II) in industrial effluent wastewater by standard addition method (recoveries &gt;96%). The proposed method was successfully applied to the determination of Cr(VI) and Pb(II) at ultratrace levels in natural drinking water and industrial effluents wastewater of Denizli. Moreover, the proposed method was compared with the literature reported method.","Ultratrace Determination of Cr(VI) and Pb(II) by Microsample Injection System Flame Atomic Spectroscopy in Drinking Water and Treated and Untreated Industrial Effluents Abs: Simple and robust analytical procedures were developed for hexavalent chromium (Cr(VI)) and lead (Pb(II)) by dispersive liquid-liquid microextraction (DLLME) using microsample injection system coupled with flame atomic absorption spectrophotometry (MIS-FAAS). For the current study, ammonium pyrrolidine dithiocarbamate (APDC), carbon tetrachloride, and ethanol were used as chelating agent, extraction solvent, and disperser solvent, respectively. The effective variables of developed method have been optimized and studied in detail. The limit of detection of Cr(VI) and Pb(II) were 0.037 and 0.054?µg/L, respectively. The enrichment factors in both cases were 400 with 40?mL of initial volumes. The relative standard deviations (RSDs, n = 6) were &lt;4%. The applicability and the accuracy of DLLME were estimated by the analysis of Cr(VI) and Pb(II) in industrial effluent wastewater by standard addition method (recoveries &gt;96%). The proposed method was successfully applied to the determination of Cr(VI) and Pb(II) at ultratrace levels in natural drinking water and industrial effluents wastewater of Denizli. Moreover, the proposed method was compared with the literature reported method."
2225042,Zheng et al. 2013,[Design and development of trace Cr(VI) sensor],"Hexavalent chromium detection in medicine capsules is generally analyzed in the laboratory, it is difficult to meet the demand for field detection, and to address this problem, a sensor which can be used for on-site detection of trace amounts of hexavalent chromium was designed. It mainly includes chemically sensitive materials, optical sensing module and signal processing module, the chemical sensitive materials is to achieve the conversion of the hexavalent chromium concentration signal, the optical sensing module is to complete a stable output of the laser light source, and the signal processing module is to complete a photoelectric conversion of the weak fluorescence signal, signal amplification, and data processing and displaying. With using the indigenously developed photoelectric acquisition, conversion and signal processing system to complete the rapid detection of trace amounts of hexavalent chromium, so the miniaturization of testing instruments and on-site detection were achieved. Experimental results show that: the sensor detection results have a good linear relationship when the hexavalent chromium concentration is 10-500 microg x L(-1), the linear equation is Y = 1.542 47 x X-2.353 47, and the linearity is 0.998 62, the detection limit reaches 10 microg x L(-1), the sensor response time is about 90 seconds, 5 capsule samples were selected to do the contrast detection, and the results show that the sensor quantitative detection data is reliable, which meets trace hexavalent low cost, fast and field detection demands.","[Design and development of trace Cr(VI) sensor] Abs: Hexavalent chromium detection in medicine capsules is generally analyzed in the laboratory, it is difficult to meet the demand for field detection, and to address this problem, a sensor which can be used for on-site detection of trace amounts of hexavalent chromium was designed. It mainly includes chemically sensitive materials, optical sensing module and signal processing module, the chemical sensitive materials is to achieve the conversion of the hexavalent chromium concentration signal, the optical sensing module is to complete a stable output of the laser light source, and the signal processing module is to complete a photoelectric conversion of the weak fluorescence signal, signal amplification, and data processing and displaying. With using the indigenously developed photoelectric acquisition, conversion and signal processing system to complete the rapid detection of trace amounts of hexavalent chromium, so the miniaturization of testing instruments and on-site detection were achieved. Experimental results show that: the sensor detection results have a good linear relationship when the hexavalent chromium concentration is 10-500 microg x L(-1), the linear equation is Y = 1.542 47 x X-2.353 47, and the linearity is 0.998 62, the detection limit reaches 10 microg x L(-1), the sensor response time is about 90 seconds, 5 capsule samples were selected to do the contrast detection, and the results show that the sensor quantitative detection data is reliable, which meets trace hexavalent low cost, fast and field detection demands."
2225041,Liu et al. 2013,"Speciation, adsorption and determination of chromium(III) and chromium(VI) on a mesoporous surface imprinted polymer adsorbent by combining inductively coupled plasma atomic emission spectrometry and UV spectrophotometry","In the present study, a Cr(III)-imprinted polymer (Cr(III)-IIP) was prepared by an easy one-step sol-gel reaction with a surface imprinting technique on the support of silica mesoporous material. A new SPE method for the speciation, separation, preconcentration, and determination of Cr(III) and Cr(VI) by inductively coupled plasma atomic emission spectrometry and UV on the mesoporous-imprinted polymer adsorbent was developed. The structure of the imprinted polymer was characterized by Fourier transform infrared spectroscopy, X-ray powder diffraction, transmission electron microscopy, and nitrogen adsorption-desorption isotherms. The adsorption kinetics, thermodynamics behavior, and recognition ability toward Cr(III) on Cr(III)-IIP and nonimprinted polymer were compared. The results showed that Cr(III)-IIP had higher selectivity and nearly a two times larger Langmuir adsorption capacity (38.50 mg/g) than that of NIP. The proposed method has been successfully applied in the determination and speciation of chromium in natural water samples with satisfactory results.","Speciation, adsorption and determination of chromium(III) and chromium(VI) on a mesoporous surface imprinted polymer adsorbent by combining inductively coupled plasma atomic emission spectrometry and UV spectrophotometry Abs: In the present study, a Cr(III)-imprinted polymer (Cr(III)-IIP) was prepared by an easy one-step sol-gel reaction with a surface imprinting technique on the support of silica mesoporous material. A new SPE method for the speciation, separation, preconcentration, and determination of Cr(III) and Cr(VI) by inductively coupled plasma atomic emission spectrometry and UV on the mesoporous-imprinted polymer adsorbent was developed. The structure of the imprinted polymer was characterized by Fourier transform infrared spectroscopy, X-ray powder diffraction, transmission electron microscopy, and nitrogen adsorption-desorption isotherms. The adsorption kinetics, thermodynamics behavior, and recognition ability toward Cr(III) on Cr(III)-IIP and nonimprinted polymer were compared. The results showed that Cr(III)-IIP had higher selectivity and nearly a two times larger Langmuir adsorption capacity (38.50 mg/g) than that of NIP. The proposed method has been successfully applied in the determination and speciation of chromium in natural water samples with satisfactory results."
2225040,Saikia et al. ,Genetic revelation of hexavalent chromium toxicity using Caenorhabditis elegans as a biosensor,"The interaction of heavy metals such as hexavalent chromium, Cr (VI) with the environment drastically influences living organisms leading to an ecological imbalance. Caenorhabditis elegans, a saprophytic nematode having 60-80% homology with human genes offers a distinct advantage to be used as a biosensor for the appraisal of heavy metal-induced environmental toxicity and risk monitoring. The present study examines the toxicity effects of K2Cr2O7 as Cr (VI) on stress-related gene expression and morphometric parameters of C. elegans under in vitro conditions to identify genetic markers for environmental pollution. Alterations in growth and modified gene expression were observed in Cr (VI)-exposed N2 worms. The 24-h median lethal concentration for Cr (VI) was observed as 158.5?mgl(-1). Use of the responses of stress-related gene expression suggests that C. elegans can be used as an efficient biosensor for figuring out the precise route of Cr (VI)-induced environmental toxicity in a quick, simple, and inexpensive manner.Journal of Exposure Science and Environmental Epidemiology advance online publication, 23 October 2013; doi:10.1038/jes.2013.66.","Genetic revelation of hexavalent chromium toxicity using Caenorhabditis elegans as a biosensor Abs: The interaction of heavy metals such as hexavalent chromium, Cr (VI) with the environment drastically influences living organisms leading to an ecological imbalance. Caenorhabditis elegans, a saprophytic nematode having 60-80% homology with human genes offers a distinct advantage to be used as a biosensor for the appraisal of heavy metal-induced environmental toxicity and risk monitoring. The present study examines the toxicity effects of K2Cr2O7 as Cr (VI) on stress-related gene expression and morphometric parameters of C. elegans under in vitro conditions to identify genetic markers for environmental pollution. Alterations in growth and modified gene expression were observed in Cr (VI)-exposed N2 worms. The 24-h median lethal concentration for Cr (VI) was observed as 158.5?mgl(-1). Use of the responses of stress-related gene expression suggests that C. elegans can be used as an efficient biosensor for figuring out the precise route of Cr (VI)-induced environmental toxicity in a quick, simple, and inexpensive manner.Journal of Exposure Science and Environmental Epidemiology advance online publication, 23 October 2013; doi:10.1038/jes.2013.66."
2225039,Tavengwa et al. 2013,"Synthesis, adsorption and selectivity studies of N-propyl quaternized magnetic poly(4-vinylpyridine) for hexavalent chromium","The ability of solid N-propyl quaternized magnetic poly(4-vinylpyridine) for the extraction of chromium(VI) in aqueous solutions was investigated. For the synthesized Cr(VI) magnetic polymers, the optimum pH obtained was 4 for both the magnetic ion imprinted polymer (IIP) and the corresponding non-ion imprinted polymer NIP. The amount of the adsorbent which gave the maximum adsorption was determined to be 20 and 65 mg for the magnetic IIP and NIP, respectively. A Cr(VI) concentration which was adsorbed maximally was 5 mg L(-1) which was therefore taken as the optimum. The maximum adsorption capacities for the magnetic polymers were 6.20 and 1.87 mg g(-1) for the magnetic IIP and NIP, respectively. The optimum time for the adsorption of the Cr(VI) analyte was determined as 40 min. The prepared magnetic ion imprinted polymer showed good selectivity towards Cr(VI). The order of selectivity of the investigated anions followed the sequence: Cr2O7(2-)&gt;SO4(2-)&gt;F(-)&gt;NO3(-).","Synthesis, adsorption and selectivity studies of N-propyl quaternized magnetic poly(4-vinylpyridine) for hexavalent chromium Abs: The ability of solid N-propyl quaternized magnetic poly(4-vinylpyridine) for the extraction of chromium(VI) in aqueous solutions was investigated. For the synthesized Cr(VI) magnetic polymers, the optimum pH obtained was 4 for both the magnetic ion imprinted polymer (IIP) and the corresponding non-ion imprinted polymer NIP. The amount of the adsorbent which gave the maximum adsorption was determined to be 20 and 65 mg for the magnetic IIP and NIP, respectively. A Cr(VI) concentration which was adsorbed maximally was 5 mg L(-1) which was therefore taken as the optimum. The maximum adsorption capacities for the magnetic polymers were 6.20 and 1.87 mg g(-1) for the magnetic IIP and NIP, respectively. The optimum time for the adsorption of the Cr(VI) analyte was determined as 40 min. The prepared magnetic ion imprinted polymer showed good selectivity towards Cr(VI). The order of selectivity of the investigated anions followed the sequence: Cr2O7(2-)&gt;SO4(2-)&gt;F(-)&gt;NO3(-)."
2225038,Gitet et al. 2013,"Speciation of chromium in soils near Sheba Leather Industry, Wukro Ethiopia","A study on speciation of chromium in soils near Sheba Leather Industry was performed by Flame Atomic Absorption (FAAS) after selective extraction of Cr(VI) using the EPA 3060A method, and oxidizing the Cr(III) residue in the soils with HNO3 and H2O2. The extraction method was evaluated using the spiking method with satisfactory results (recoveries&gt;95% and RSDs&lt;5%). The limit of detection (LOD) for Cr(VI) based on three times the standard deviations of the blank (for n=5) was 0.56 µg g(-1). Statistical evaluation indicated that the comparison of the sum of the concentrations of chromium species to that of the total concentration of chromium do not show any difference at 95% level of confidence. Besides, no statistically significant difference at 95% confidence level was observed between the UV-vis spectrophotometry and FAAS results for Cr(VI). However, it is observed that selective extraction of Cr(VI) using EPA 3060A and subsequent determination by FAAS is simple and faster compared to the other method. Furthermore, for comparison and as control two soil samples collected from a distance of about 2 km from the main Industry and effluent stream. The results indicate that higher total chromium content was observed in soils collected from the target area. Nevertheless, the maximum concentrations of Cr(VI) found in soil samples collected around Sheba Leather Industry was 9.9 µg g(-1) and are within the acceptable level of 10 µg g(-1) in accordance with the WHO.","Speciation of chromium in soils near Sheba Leather Industry, Wukro Ethiopia Abs: A study on speciation of chromium in soils near Sheba Leather Industry was performed by Flame Atomic Absorption (FAAS) after selective extraction of Cr(VI) using the EPA 3060A method, and oxidizing the Cr(III) residue in the soils with HNO3 and H2O2. The extraction method was evaluated using the spiking method with satisfactory results (recoveries&gt;95% and RSDs&lt;5%). The limit of detection (LOD) for Cr(VI) based on three times the standard deviations of the blank (for n=5) was 0.56 µg g(-1). Statistical evaluation indicated that the comparison of the sum of the concentrations of chromium species to that of the total concentration of chromium do not show any difference at 95% level of confidence. Besides, no statistically significant difference at 95% confidence level was observed between the UV-vis spectrophotometry and FAAS results for Cr(VI). However, it is observed that selective extraction of Cr(VI) using EPA 3060A and subsequent determination by FAAS is simple and faster compared to the other method. Furthermore, for comparison and as control two soil samples collected from a distance of about 2 km from the main Industry and effluent stream. The results indicate that higher total chromium content was observed in soils collected from the target area. Nevertheless, the maximum concentrations of Cr(VI) found in soil samples collected around Sheba Leather Industry was 9.9 µg g(-1) and are within the acceptable level of 10 µg g(-1) in accordance with the WHO."
2225037,Lv et al. 2013,Fe(0)-Fe3O4 nanocomposites embedded polyvinyl alcohol/sodium alginate beads for chromium (VI) removal,"In this study, Fe(0)-Fe3O4 nanocomposites embedded polyvinyl alcohol (PVA)/sodium alginate (SA) beads were synthesized, which exhibited an excellent physical properties and catalytic reactivity, and a robust performance of post-separation (complete separation using a simple grille) and reusability (efficiency of 69.8% after four runs) in Cr(VI) removal. 5.0 wt% PVA with 1.5 wt% SA was the optimal proportion for beads molding, and the followed acidification and reduction treatments were critical to ensure high mechanical strength and high Cr(VI) removal ability of beads. Effects of Fe(0) and Fe3O4 mass fraction, initial pH and Cr(VI) concentration on final removal efficiency were also evaluated. Merely 0.075 wt% Fe(0) together with 0.30 wt% Fe3O4 was sufficient to deal with 20 mg L(-1) Cr(VI) solution. The efficiency decreased from 100 to 79.5% as initial Cr(VI) increased from 5 to 40 mg L(-1), while from 99.3 to 76.3% with increasing pH from 3.0 to 11.0. This work provides a practical and high-efficient method for heavy metal removal from water body, and simultaneously solves the problems in stabilization, separation and regeneration of Fe(0) nanoparticles.","Fe(0)-Fe3O4 nanocomposites embedded polyvinyl alcohol/sodium alginate beads for chromium (VI) removal Abs: In this study, Fe(0)-Fe3O4 nanocomposites embedded polyvinyl alcohol (PVA)/sodium alginate (SA) beads were synthesized, which exhibited an excellent physical properties and catalytic reactivity, and a robust performance of post-separation (complete separation using a simple grille) and reusability (efficiency of 69.8% after four runs) in Cr(VI) removal. 5.0 wt% PVA with 1.5 wt% SA was the optimal proportion for beads molding, and the followed acidification and reduction treatments were critical to ensure high mechanical strength and high Cr(VI) removal ability of beads. Effects of Fe(0) and Fe3O4 mass fraction, initial pH and Cr(VI) concentration on final removal efficiency were also evaluated. Merely 0.075 wt% Fe(0) together with 0.30 wt% Fe3O4 was sufficient to deal with 20 mg L(-1) Cr(VI) solution. The efficiency decreased from 100 to 79.5% as initial Cr(VI) increased from 5 to 40 mg L(-1), while from 99.3 to 76.3% with increasing pH from 3.0 to 11.0. This work provides a practical and high-efficient method for heavy metal removal from water body, and simultaneously solves the problems in stabilization, separation and regeneration of Fe(0) nanoparticles."
2225036,Mosier-Boss and  Putnam 2013,Detection of hexavalent chromium using gold/4-(2-mercaptoethyl) pyridinium surface enhanced Raman scattering-active capture matrices,"In this communication, the fabrication of SERS-active capture matrices for the detection of hexavalent chromium is described. The amine groups of amine-modified magnetic microparticles were used to immobilize gold colloidal particles. Once immobilized, the gold was reacted with 4-(2-mercaptoethyl) pyridinium (MEP) hydrochloride to form a self-assembled monolayer (SAM). The MEP SAM exhibits great selectivity for hexavalent chromium. It was shown that calibration curves could be generated by ratioing MEP peaks that increased in intensity upon complexation with chromate with a peak that did not change. Flow experiments, using Au/MEP capture matrices held in place by a magnet, showed instantaneous response to changes in chromate concentration.","Detection of hexavalent chromium using gold/4-(2-mercaptoethyl) pyridinium surface enhanced Raman scattering-active capture matrices Abs: In this communication, the fabrication of SERS-active capture matrices for the detection of hexavalent chromium is described. The amine groups of amine-modified magnetic microparticles were used to immobilize gold colloidal particles. Once immobilized, the gold was reacted with 4-(2-mercaptoethyl) pyridinium (MEP) hydrochloride to form a self-assembled monolayer (SAM). The MEP SAM exhibits great selectivity for hexavalent chromium. It was shown that calibration curves could be generated by ratioing MEP peaks that increased in intensity upon complexation with chromate with a peak that did not change. Flow experiments, using Au/MEP capture matrices held in place by a magnet, showed instantaneous response to changes in chromate concentration."
2225035,Šillerová et al. 2014,Isotope fractionation and spectroscopic analysis as an evidence of Cr(VI) reduction during biosorption,"This work investigates the mechanisms behind Cr(VI) biosorption/reduction on three biomaterials (brewers draff, grape waste and synthetic humic acid). Coupled Cr isotope analysis with ICP-OES, XPS and SEM was tested as a novel approach to study the reduction of Cr(VI) by the biomaterials. The Cr(VI) biosorption process was accompanied with heavier Cr isotopes enrichment in the remaining Cr(VI) fraction. A significant fractionation of Cr stable isotopes was observed with no significant pH effect; ?(53)Cr of the remaining fraction ranged from 0.2‰ to 1.9‰ while ?(53)Cr of the product (sorbed Cr) ranged from -1.2‰ to -2.8‰. The Rayleigh fractionation model fitted well the measured data and Cr isotope analysis provides thus an efficient tool to quantify Cr(VI) reduction by different biomaterials. In general, the sorption/reduction potential of the three studied biomaterials decreased in the following order: grape waste&gt;humic acids&gt;brewers draff.","Isotope fractionation and spectroscopic analysis as an evidence of Cr(VI) reduction during biosorption Abs: This work investigates the mechanisms behind Cr(VI) biosorption/reduction on three biomaterials (brewers draff, grape waste and synthetic humic acid). Coupled Cr isotope analysis with ICP-OES, XPS and SEM was tested as a novel approach to study the reduction of Cr(VI) by the biomaterials. The Cr(VI) biosorption process was accompanied with heavier Cr isotopes enrichment in the remaining Cr(VI) fraction. A significant fractionation of Cr stable isotopes was observed with no significant pH effect; ?(53)Cr of the remaining fraction ranged from 0.2‰ to 1.9‰ while ?(53)Cr of the product (sorbed Cr) ranged from -1.2‰ to -2.8‰. The Rayleigh fractionation model fitted well the measured data and Cr isotope analysis provides thus an efficient tool to quantify Cr(VI) reduction by different biomaterials. In general, the sorption/reduction potential of the three studied biomaterials decreased in the following order: grape waste&gt;humic acids&gt;brewers draff."
2225034,Fuzinatto et al. 2013,"Induction of micronucleus of Oreochromis niloticus exposed to waters from the Cubatão do Sul River, southern Brazil","In an effort to characterize the pollution of surface waters by potentially genotoxic agents, this study aimed at assessing the frequency of micronucleated (MN) erythrocytes of the fish species, Oreochromis niloticus, from the Cubatão do Sul River. This river is the source of drinking water for the region of Florianópolis, capital of Santa Catarina State, Brazil. Negative control fish showed low frequency of MN, ranging between 0.49‰ and 0.90‰. Positive control (potassium dichromate 2.5 mg/L) organisms showed high MN frequency (16.82-17.25‰). The MN frequency increased along the river (Site 1--1.24‰ winter 2011; Site 4--9.76‰ summer 2011). Based on the observation of elevated MN erythrocytes frequency in O. niloticus exposed to water samples from along the river course, we conclude that the complex environmental mixtures of water from the Cubatão do Sul River have genotoxic potential. This genotoxicity most likely originated from agricultural runoff and domestic effluents released without treatment, based on the evidence from literature data and a survey in the region. This study provides a scientific basis for future studies regarding the genotoxicity of complex environmental mixtures in natural environments.","Induction of micronucleus of Oreochromis niloticus exposed to waters from the Cubatão do Sul River, southern Brazil Abs: In an effort to characterize the pollution of surface waters by potentially genotoxic agents, this study aimed at assessing the frequency of micronucleated (MN) erythrocytes of the fish species, Oreochromis niloticus, from the Cubatão do Sul River. This river is the source of drinking water for the region of Florianópolis, capital of Santa Catarina State, Brazil. Negative control fish showed low frequency of MN, ranging between 0.49‰ and 0.90‰. Positive control (potassium dichromate 2.5 mg/L) organisms showed high MN frequency (16.82-17.25‰). The MN frequency increased along the river (Site 1--1.24‰ winter 2011; Site 4--9.76‰ summer 2011). Based on the observation of elevated MN erythrocytes frequency in O. niloticus exposed to water samples from along the river course, we conclude that the complex environmental mixtures of water from the Cubatão do Sul River have genotoxic potential. This genotoxicity most likely originated from agricultural runoff and domestic effluents released without treatment, based on the evidence from literature data and a survey in the region. This study provides a scientific basis for future studies regarding the genotoxicity of complex environmental mixtures in natural environments."
2225033,Kumar et al. 2014,An optimised protocol for molecular identification of Eimeria from chickens,"Molecular approaches supporting identification of Eimeria parasites infecting chickens have been available for more than 20 years, although they have largely failed to replace traditional measures such as microscopy and pathology. Limitations of microscopy-led diagnostics, including a requirement for specialist parasitological expertise and low sample throughput, are yet to be outweighed by the difficulties associated with accessing genomic DNA from environmental Eimeria samples. A key step towards the use of Eimeria species-specific PCR as a sensitive and reproducible discriminatory tool for use in the field is the production of a standardised protocol that includes sample collection and DNA template preparation, as well as primer selection from the numerous PCR assays now published. Such a protocol will facilitate development of valuable epidemiological datasets which may be easily compared between studies and laboratories. The outcome of an optimisation process undertaken in laboratories in India and the UK is described here, identifying four steps. First, samples were collected into a 2% (w/v) potassium dichromate solution. Second, oocysts were enriched by flotation in saturated saline. Third, genomic DNA was extracted using a QIAamp DNA Stool mini kit protocol including a mechanical homogenisation step. Finally, nested PCR was carried out using previously published primers targeting the internal transcribed spacer region 1 (ITS-1). Alternative methods tested included sample processing in the presence of faecal material, DNA extraction using a traditional phenol/chloroform protocol, the use of SCAR multiplex PCR (one tube and two tube versions) and speciation using the morphometric tool COCCIMORPH for the first time with field samples.","An optimised protocol for molecular identification of Eimeria from chickens Abs: Molecular approaches supporting identification of Eimeria parasites infecting chickens have been available for more than 20 years, although they have largely failed to replace traditional measures such as microscopy and pathology. Limitations of microscopy-led diagnostics, including a requirement for specialist parasitological expertise and low sample throughput, are yet to be outweighed by the difficulties associated with accessing genomic DNA from environmental Eimeria samples. A key step towards the use of Eimeria species-specific PCR as a sensitive and reproducible discriminatory tool for use in the field is the production of a standardised protocol that includes sample collection and DNA template preparation, as well as primer selection from the numerous PCR assays now published. Such a protocol will facilitate development of valuable epidemiological datasets which may be easily compared between studies and laboratories. The outcome of an optimisation process undertaken in laboratories in India and the UK is described here, identifying four steps. First, samples were collected into a 2% (w/v) potassium dichromate solution. Second, oocysts were enriched by flotation in saturated saline. Third, genomic DNA was extracted using a QIAamp DNA Stool mini kit protocol including a mechanical homogenisation step. Finally, nested PCR was carried out using previously published primers targeting the internal transcribed spacer region 1 (ITS-1). Alternative methods tested included sample processing in the presence of faecal material, DNA extraction using a traditional phenol/chloroform protocol, the use of SCAR multiplex PCR (one tube and two tube versions) and speciation using the morphometric tool COCCIMORPH for the first time with field samples."
2225032,Balakrishnan et al. 2013,An evaluation of the protective role of ?-tocopherol on free radical induced hepatotoxicity and nephrotoxicity due to chromium in rats,"<strong>AIM: </strong>To avert the health problems induced by many environmental pollutants, available antioxidants have been evaluated. The present study was aimed to investigate whether ?-tocopherol could protect the hexavalent chromium (Cr VI)-induced peroxidation in the liver and kidney and to explore the underlying mechanism of the same.<br /><br /><strong>MATERIALS AND METHODS: </strong>A total of 24 Wistar adult female rats were equally divided into four groups. Group 1 served as control while Groups 2 and 3 were administered K2Cr2O7(10 mg/kg b.wt. s.c. single dose). In addition to (Cr VI), Group 3 also received ?-tocopherol (125 mg/kg, daily) by oral gavage for 14 days. Group 4 was maintained as ?-tocopherol control (dose as above). At the end of 14 days, blood samples were drawn for hematology. Subsequently, all the rats were sacrificed to collect liver and kidney samples for assay of tissue peroxidation markers, antioxidant markers and functional markers and histopathology.<br /><br /><strong>RESULTS: </strong>Administration of chromium (Cr VI) in Group 2 significantly (P &lt; 0.05) reduced the antioxidant markers such as superoxide dismutase and reduced glutathione along with significant (P &lt; 0.05) increase in peroxidation markers such as malondialdehyde and protein carbonyls in the liver and kidney as compared with other groups. The functional markers in serum such as total protein was decreased significantly (P &lt; 0.05), whereas other functional markers viz. alanine transaminase, blood urea nitrogen and creatinine were increased significantly (P &lt; 0.05) in Group 2 as compared with the other groups. Significant (P &lt; 0.05) decrease in hemoglobin, packed cell volume, total erythrocyte count, mean corpuscular volume, mean corpuscular hemoglobin and total leukocyte count were observed in Cr VI treated Group 2 rats. Prominent pathological changes were observed in the liver and kidney of Group 2. Co-treatment with ?-tocopherol in Group 3 rats significantly (P &lt; 0.05) reversed the Cr VI induced changes. The parameters in the study in Group 4 did not differ as compared with Group 1.<br /><br /><strong>CONCLUSIONS: </strong>?-tocopherol exhibited protective effect against Cr VI-induced damage to the liver and kidney by inhibition of lipid peroxidation owing its antioxidant activity.","An evaluation of the protective role of ?-tocopherol on free radical induced hepatotoxicity and nephrotoxicity due to chromium in rats Abs: <strong>AIM: </strong>To avert the health problems induced by many environmental pollutants, available antioxidants have been evaluated. The present study was aimed to investigate whether ?-tocopherol could protect the hexavalent chromium (Cr VI)-induced peroxidation in the liver and kidney and to explore the underlying mechanism of the same.<br /><br /><strong>MATERIALS AND METHODS: </strong>A total of 24 Wistar adult female rats were equally divided into four groups. Group 1 served as control while Groups 2 and 3 were administered K2Cr2O7(10 mg/kg b.wt. s.c. single dose). In addition to (Cr VI), Group 3 also received ?-tocopherol (125 mg/kg, daily) by oral gavage for 14 days. Group 4 was maintained as ?-tocopherol control (dose as above). At the end of 14 days, blood samples were drawn for hematology. Subsequently, all the rats were sacrificed to collect liver and kidney samples for assay of tissue peroxidation markers, antioxidant markers and functional markers and histopathology.<br /><br /><strong>RESULTS: </strong>Administration of chromium (Cr VI) in Group 2 significantly (P &lt; 0.05) reduced the antioxidant markers such as superoxide dismutase and reduced glutathione along with significant (P &lt; 0.05) increase in peroxidation markers such as malondialdehyde and protein carbonyls in the liver and kidney as compared with other groups. The functional markers in serum such as total protein was decreased significantly (P &lt; 0.05), whereas other functional markers viz. alanine transaminase, blood urea nitrogen and creatinine were increased significantly (P &lt; 0.05) in Group 2 as compared with the other groups. Significant (P &lt; 0.05) decrease in hemoglobin, packed cell volume, total erythrocyte count, mean corpuscular volume, mean corpuscular hemoglobin and total leukocyte count were observed in Cr VI treated Group 2 rats. Prominent pathological changes were observed in the liver and kidney of Group 2. Co-treatment with ?-tocopherol in Group 3 rats significantly (P &lt; 0.05) reversed the Cr VI induced changes. The parameters in the study in Group 4 did not differ as compared with Group 1.<br /><br /><strong>CONCLUSIONS: </strong>?-tocopherol exhibited protective effect against Cr VI-induced damage to the liver and kidney by inhibition of lipid peroxidation owing its antioxidant activity."
2225031,Liu et al. 2014,Iron species in layered clay: efficient electron shuttles for simultaneous conversion of dyes and Cr(VI),"The simultaneous reduction of Chromium(VI) (Cr(VI)) and oxidation of cationic dyes in dispersions of Montmorillonite K10 (MK10) were examined under visible irradiation (?&gt;420 nm). The iron species (i.e. iron oxides, structural iron and exchangeable interlayer iron) in layered clays are active for catalytically reducing Cr(VI) by using Malachite green (MG) and Rhodamine B (RhB) as the electron donors. Molecular oxygen does not have a significant effect on clay-catalyzed Cr(VI) reduction, but is important for oxidative degradation of dye pollutants. MK10 catalysts are stable and reusable, and are therefore considered as a promising naturally-abundant material for decontamination of dye and heavy metals.","Iron species in layered clay: efficient electron shuttles for simultaneous conversion of dyes and Cr(VI) Abs: The simultaneous reduction of Chromium(VI) (Cr(VI)) and oxidation of cationic dyes in dispersions of Montmorillonite K10 (MK10) were examined under visible irradiation (?&gt;420 nm). The iron species (i.e. iron oxides, structural iron and exchangeable interlayer iron) in layered clays are active for catalytically reducing Cr(VI) by using Malachite green (MG) and Rhodamine B (RhB) as the electron donors. Molecular oxygen does not have a significant effect on clay-catalyzed Cr(VI) reduction, but is important for oxidative degradation of dye pollutants. MK10 catalysts are stable and reusable, and are therefore considered as a promising naturally-abundant material for decontamination of dye and heavy metals."
2225030,Kaprara et al. 2013,Cu-Zn powders as potential Cr(VI) adsorbents for drinking water,"This work examines the possibility of applying CuZn alloys as a reducing medium for the efficient removal of hexavalent chromium from drinking water. In an effort to develop a route for producing powders of CuZn alloys under mild conditions and investigate the optimum composition for such application, a series of alloys in the form of powders were prepared, by a sequence of Cu and Zn ball-milling and low temperature annealing. Batch Cr(VI) removal tests, performed to evaluate and compare the efficiency of the products under typical natural water parameters (pH 7 and natural-like water), indicated that the best performing material have a composition around 50 wt% Cu. The dominant reduction mechanisms are both the corrosion of the alloy surface and the electron transfer to the solution. The behavior of granulated CuZn media was tested in rapid-scale column tests using the commercial KDF which verified the high potential of CuZn alloys in Cr(VI) removal. Nevertheless, Cu and Zn leaching problems should be also considered.","Cu-Zn powders as potential Cr(VI) adsorbents for drinking water Abs: This work examines the possibility of applying CuZn alloys as a reducing medium for the efficient removal of hexavalent chromium from drinking water. In an effort to develop a route for producing powders of CuZn alloys under mild conditions and investigate the optimum composition for such application, a series of alloys in the form of powders were prepared, by a sequence of Cu and Zn ball-milling and low temperature annealing. Batch Cr(VI) removal tests, performed to evaluate and compare the efficiency of the products under typical natural water parameters (pH 7 and natural-like water), indicated that the best performing material have a composition around 50 wt% Cu. The dominant reduction mechanisms are both the corrosion of the alloy surface and the electron transfer to the solution. The behavior of granulated CuZn media was tested in rapid-scale column tests using the commercial KDF which verified the high potential of CuZn alloys in Cr(VI) removal. Nevertheless, Cu and Zn leaching problems should be also considered."
2225029,Brose and  James 2013,"Hexavalent chromium reduction by tartaric acid and isopropyl alcohol in Mid-Atlantic soils and the role of Mn(III,IV)(hydr)oxides","Chromium is a naturally occurring transition metal and a soil contaminant in the Cr(VI) oxidation state, but reduction of Cr(VI) to Cr(III) mitigates its toxicity. Tartaric acid reduces Cr(VI) via a termolecular complex with isopropyl alcohol and Cr(VI), but its efficacy in soils has not been demonstrated. Five Mid-Atlantic soils from Maryland, U.S. were examined for their potential to enhance the reduction of Cr(VI). A control treatment (no soil +12 mM tartaric acid + 0.29 M isopropyl alcohol) reduced 0.37 mM Cr(VI) (19%) in 99 h. Reduction was enhanced to 1.97 mM (99%) with addition of a Russett Ap soil horizon (fine-loamy, mixed, semiactive, mesic Typic Hapludult). With a half-life of 18.7 h, the rate of reduction of Cr(VI) with the Russett soil sample was 20 times faster than with no soil (371 h). Soil Mn was solubilized in this reaction and plays a role in the enhanced reduction of Cr(VI). Mn(III/IV)(hydr)oxide-coated quartz sand reduced 1.24 mM (62%) Cr(VI), with all of the Mn(III,IV)(hydr)oxides solubilized. The addition of isopropyl alcohol and tartaric acid to soils enhances the reduction of Cr(VI), and this reduction is further enhanced by the catalytic behavior of Mn(II) from easily reducible Mn(III,IV)(hydr)oxides in soil.","Hexavalent chromium reduction by tartaric acid and isopropyl alcohol in Mid-Atlantic soils and the role of Mn(III,IV)(hydr)oxides Abs: Chromium is a naturally occurring transition metal and a soil contaminant in the Cr(VI) oxidation state, but reduction of Cr(VI) to Cr(III) mitigates its toxicity. Tartaric acid reduces Cr(VI) via a termolecular complex with isopropyl alcohol and Cr(VI), but its efficacy in soils has not been demonstrated. Five Mid-Atlantic soils from Maryland, U.S. were examined for their potential to enhance the reduction of Cr(VI). A control treatment (no soil +12 mM tartaric acid + 0.29 M isopropyl alcohol) reduced 0.37 mM Cr(VI) (19%) in 99 h. Reduction was enhanced to 1.97 mM (99%) with addition of a Russett Ap soil horizon (fine-loamy, mixed, semiactive, mesic Typic Hapludult). With a half-life of 18.7 h, the rate of reduction of Cr(VI) with the Russett soil sample was 20 times faster than with no soil (371 h). Soil Mn was solubilized in this reaction and plays a role in the enhanced reduction of Cr(VI). Mn(III/IV)(hydr)oxide-coated quartz sand reduced 1.24 mM (62%) Cr(VI), with all of the Mn(III,IV)(hydr)oxides solubilized. The addition of isopropyl alcohol and tartaric acid to soils enhances the reduction of Cr(VI), and this reduction is further enhanced by the catalytic behavior of Mn(II) from easily reducible Mn(III,IV)(hydr)oxides in soil."
2225028,Das et al. 2014,"Investigation on mechanism of Cr(VI) reduction and removal by Bacillus amyloliquefaciens, a novel chromate tolerant bacterium isolated from chromite mine soil","A strain CSB 9 isolated from chromite mine soil of Sukinda, India was identified as Bacillus amyloliquefaciens based on biochemical and 16S rRNA gene sequencing. The strain exhibited relatively high tolerance to Cr(VI) (?900mgL(-1)) and fast reduction rate of 2.22mg Cr(VI) L(-1)h(-1), under optimized conditions of 100mgL(-1) Cr(VI), pH 7 and temperature 35°C within 45h. Mechanism of Cr(VI) reduction as well as nature and fate of the reduced product were studied to determine the scope of removal of reduced Cr(III) end product. AAS analyses of the culture products treated with Cr(VI) for 45h showed the distribution of Cr(III) in pellet and culture supernatant to be 37.4±1.7 and 62.6±3.4mgL(-1), respectively. In SEM images, the bacterial pellets with Cr(VI) treatment appeared coagulated, rough and porous whereas the pellets without Cr(VI) treatment appeared regular, smooth and non-porous in structure. SEM-EDX of the bacterial precipitates under Cr(VI) treatment revealed immobilization of Cr(III) species on the bacterial cell surface. Further Raman spectroscopy analysis confirmed the presence of Cr(III) species, with characteristic peak at around 600cm(-1). TEM-EDX study of the bacterial precipitates under Cr(VI) treatment showed intracellular deposition of Cr(III) which are in nanometric range. Further characterization of reduced product by XRD, FT-IR and SAED analyses suggested the formation of poorly crystalline end products. A Cr(VI) removal mechanism considering both the surface immobilization and intracellular accumulation of Cr(III) along with the formation of coagulated cell precipitate by living B. amyloliquefaciens was suggested.","Investigation on mechanism of Cr(VI) reduction and removal by Bacillus amyloliquefaciens, a novel chromate tolerant bacterium isolated from chromite mine soil Abs: A strain CSB 9 isolated from chromite mine soil of Sukinda, India was identified as Bacillus amyloliquefaciens based on biochemical and 16S rRNA gene sequencing. The strain exhibited relatively high tolerance to Cr(VI) (?900mgL(-1)) and fast reduction rate of 2.22mg Cr(VI) L(-1)h(-1), under optimized conditions of 100mgL(-1) Cr(VI), pH 7 and temperature 35°C within 45h. Mechanism of Cr(VI) reduction as well as nature and fate of the reduced product were studied to determine the scope of removal of reduced Cr(III) end product. AAS analyses of the culture products treated with Cr(VI) for 45h showed the distribution of Cr(III) in pellet and culture supernatant to be 37.4±1.7 and 62.6±3.4mgL(-1), respectively. In SEM images, the bacterial pellets with Cr(VI) treatment appeared coagulated, rough and porous whereas the pellets without Cr(VI) treatment appeared regular, smooth and non-porous in structure. SEM-EDX of the bacterial precipitates under Cr(VI) treatment revealed immobilization of Cr(III) species on the bacterial cell surface. Further Raman spectroscopy analysis confirmed the presence of Cr(III) species, with characteristic peak at around 600cm(-1). TEM-EDX study of the bacterial precipitates under Cr(VI) treatment showed intracellular deposition of Cr(III) which are in nanometric range. Further characterization of reduced product by XRD, FT-IR and SAED analyses suggested the formation of poorly crystalline end products. A Cr(VI) removal mechanism considering both the surface immobilization and intracellular accumulation of Cr(III) along with the formation of coagulated cell precipitate by living B. amyloliquefaciens was suggested."
2225027,Ben Hamida et al. 2013,The protective effect of propylthiouracil against hepatotoxicity induced by chromium in adult mice,"Environmental and occupational exposure to chromium compounds, especially hexavalent chromium (Cr(VI)), is widely recognized as potentially hepatotoxic in humans and animals. Its toxicity is associated with overproduction of free radicals, which induces oxidative damage. This study focused on the possible protective effect of propylthiouracil (PTU) against potassium dichromate (K2Cr2O7). Female mice were divided into four groups (groups I-IV) with seven animals in each group. Group I served as a control, which received tap water; group II received K2Cr2O7 alone (75 mg kg(-1) body weight (b.w.)) via drinking water; group III received both K2Cr2O7 via drinking water and PTU by intramuscular injection at a dose 2.5 mg/100 g(-1) b.w. twice a week, and group IV received PTU alone twice a week for 30 days. Exposure of mice to Cr promoted oxidative stress with an increase in malondialdehyde, protein carbonyl, and advanced oxidation protein product levels. Nonenzymatic antioxidants such as glutathione, nonprotein thiol, vitamin C levels and enzymatic antioxidant activities such as glutathione peroxidase and superoxide dismutase were decreased, while catalase activity was increased. Biomarkers of liver injury such as aspartate and alanine transaminases, lactate dehydrogenase activities, bilirubin, albumin, and glucose levels were increased, while triglyceride and cholesterol levels decreased. Coadministration of PTU restored the above-mentioned parameters to near-normal values. The histological findings confirmed the biochemical results.","The protective effect of propylthiouracil against hepatotoxicity induced by chromium in adult mice Abs: Environmental and occupational exposure to chromium compounds, especially hexavalent chromium (Cr(VI)), is widely recognized as potentially hepatotoxic in humans and animals. Its toxicity is associated with overproduction of free radicals, which induces oxidative damage. This study focused on the possible protective effect of propylthiouracil (PTU) against potassium dichromate (K2Cr2O7). Female mice were divided into four groups (groups I-IV) with seven animals in each group. Group I served as a control, which received tap water; group II received K2Cr2O7 alone (75 mg kg(-1) body weight (b.w.)) via drinking water; group III received both K2Cr2O7 via drinking water and PTU by intramuscular injection at a dose 2.5 mg/100 g(-1) b.w. twice a week, and group IV received PTU alone twice a week for 30 days. Exposure of mice to Cr promoted oxidative stress with an increase in malondialdehyde, protein carbonyl, and advanced oxidation protein product levels. Nonenzymatic antioxidants such as glutathione, nonprotein thiol, vitamin C levels and enzymatic antioxidant activities such as glutathione peroxidase and superoxide dismutase were decreased, while catalase activity was increased. Biomarkers of liver injury such as aspartate and alanine transaminases, lactate dehydrogenase activities, bilirubin, albumin, and glucose levels were increased, while triglyceride and cholesterol levels decreased. Coadministration of PTU restored the above-mentioned parameters to near-normal values. The histological findings confirmed the biochemical results."
2225026,Chakraborty et al. 2013,Performance study of chromium (VI) removal in presence of phenol in a continuous packed bed reactor by Escherichia coli isolated from East Calcutta Wetlands,"Organic pollutants, like phenol, along with heavy metals, like chromium, are present in various industrial effluents that pose serious health hazard to humans. The present study looked at removal of chromium (VI) in presence of phenol in a counter-current continuous packed bed reactor packed with E. coli cells immobilized on clay chips. The cells removed 85% of 500 mg/L of chromium (VI) from MS media containing glucose. Glucose was then replaced by 500 mg/L phenol. Temperature and pH of the MS media prior to addition of phenol were 30°C and 7, respectively. Hydraulic retention times of phenol- and chromium (VI)-containing synthetic media and air flow rates were varied to study the removal efficiency of the reactor system. Then temperature conditions of the reactor system were varied from 10°C to 50°C, the optimum being 30°C. The pH of the media was varied from pH 1 to pH 12, and the optimum pH was found to be 7. The maximum removal efficiency of 77.7% was achieved for synthetic media containing phenol and chromium (VI) in the continuous reactor system at optimized conditions, namely, hydraulic retention time at 4.44 hr, air flow rate at 2.5 lpm, temperature at 30°C, and pH at 7.","Performance study of chromium (VI) removal in presence of phenol in a continuous packed bed reactor by Escherichia coli isolated from East Calcutta Wetlands Abs: Organic pollutants, like phenol, along with heavy metals, like chromium, are present in various industrial effluents that pose serious health hazard to humans. The present study looked at removal of chromium (VI) in presence of phenol in a counter-current continuous packed bed reactor packed with E. coli cells immobilized on clay chips. The cells removed 85% of 500 mg/L of chromium (VI) from MS media containing glucose. Glucose was then replaced by 500 mg/L phenol. Temperature and pH of the MS media prior to addition of phenol were 30°C and 7, respectively. Hydraulic retention times of phenol- and chromium (VI)-containing synthetic media and air flow rates were varied to study the removal efficiency of the reactor system. Then temperature conditions of the reactor system were varied from 10°C to 50°C, the optimum being 30°C. The pH of the media was varied from pH 1 to pH 12, and the optimum pH was found to be 7. The maximum removal efficiency of 77.7% was achieved for synthetic media containing phenol and chromium (VI) in the continuous reactor system at optimized conditions, namely, hydraulic retention time at 4.44 hr, air flow rate at 2.5 lpm, temperature at 30°C, and pH at 7."
2225025,Del Bubba et al. 2013,"Chromium accumulation and changes in plant growth, selected phenolics and sugars of wild type and genetically modified Nicotiana langsdorffii","Chromium accumulation, dry weight (DW) biomass yield, water content and concentrations of some selected phenolic compounds and carbohydrates were determined in root and shoot of Nicotiana langsdorffii, either wild type (WT) or genetically modified by the insertion of GR and rolC genes, in response to the presence of Cr(VI) in the growth medium. A biomass decrease was observed for WT plants, but not for GR and rolC transformations, in response to Cr(VI) in the growth medium, highlighting a stress situation only in WT line. Shoot chromium concentrations were in all cases about 300 mg kg(-1) DW. In root higher concentrations were found in rolC than in GR and WT (3843, 2600 and 2751 mg kg(-1) DW, respectively). Based on the DW biomass, GR and WT accumulated higher chromium quantities than rolC, both in root (330 and 424 versus 85 ?g Cr per plant) and shoot (282 and 275 versus 121 ?g Cr per plant). Therefore, GR should be preferred to WT as a promising candidate for chromium phytoremediation. Metabolic shifts of sugars and phenolics were generally observed in response to either gene insertions or exposure to Cr(VI), being the latter more related to the resistance to Cr(VI) than the former.","Chromium accumulation and changes in plant growth, selected phenolics and sugars of wild type and genetically modified Nicotiana langsdorffii Abs: Chromium accumulation, dry weight (DW) biomass yield, water content and concentrations of some selected phenolic compounds and carbohydrates were determined in root and shoot of Nicotiana langsdorffii, either wild type (WT) or genetically modified by the insertion of GR and rolC genes, in response to the presence of Cr(VI) in the growth medium. A biomass decrease was observed for WT plants, but not for GR and rolC transformations, in response to Cr(VI) in the growth medium, highlighting a stress situation only in WT line. Shoot chromium concentrations were in all cases about 300 mg kg(-1) DW. In root higher concentrations were found in rolC than in GR and WT (3843, 2600 and 2751 mg kg(-1) DW, respectively). Based on the DW biomass, GR and WT accumulated higher chromium quantities than rolC, both in root (330 and 424 versus 85 ?g Cr per plant) and shoot (282 and 275 versus 121 ?g Cr per plant). Therefore, GR should be preferred to WT as a promising candidate for chromium phytoremediation. Metabolic shifts of sugars and phenolics were generally observed in response to either gene insertions or exposure to Cr(VI), being the latter more related to the resistance to Cr(VI) than the former."
2225024,Martone et al. 2013,Determination of chromium species in dietary supplements using speciated isotope dilution mass spectrometry with mass balance,"In order to determine the health impact of chromium in dietary supplements, the Cr(III) and Cr(VI) must be independently measured and verified with mass balance (sum of both species equaling independent measurements of total chromium), as both may be present in finished products. Because Cr(III) is stable in acidic conditions and Cr(VI) in alkaline conditions, interconversions between species may occur in complex matrices and during analytical extraction, increasing the difficulty of quantification. A study was conducted to determine Cr(VI) and Cr(III) in dietary supplements. EPA Method 3060A extraction protocol was performed to extract Cr(VI), and EPA Method 3052 was performed on the extracted residue to digest the remaining Cr(III). Speciated isotope dilution mass spectrometry (SIDMS), as described in the EPA Method 6800 (update V), was implemented with ion-exchange chromatography inductively coupled plasma mass spectrometry (IC-ICP-MS). Method 6800 uniquely enables tracking and correcting for the bidirectional chromium interspecies conversions that occur during extraction and sample handling prior to instrumental analysis. Mass balance results indicated that the off-the-shelf dietary supplements analyzed during this study contained hexavalent chromium ranging from &lt;DL (detection limit) to 122.4 ± 13.0 ?g/g, which corresponds to concentrations from below detection levels to up to 16% of the total chromium content. This type of variation in the final products raises public health issues and points to a need to use a robust method that can accurately and reliably make species measurements including correcting for species conversions.","Determination of chromium species in dietary supplements using speciated isotope dilution mass spectrometry with mass balance Abs: In order to determine the health impact of chromium in dietary supplements, the Cr(III) and Cr(VI) must be independently measured and verified with mass balance (sum of both species equaling independent measurements of total chromium), as both may be present in finished products. Because Cr(III) is stable in acidic conditions and Cr(VI) in alkaline conditions, interconversions between species may occur in complex matrices and during analytical extraction, increasing the difficulty of quantification. A study was conducted to determine Cr(VI) and Cr(III) in dietary supplements. EPA Method 3060A extraction protocol was performed to extract Cr(VI), and EPA Method 3052 was performed on the extracted residue to digest the remaining Cr(III). Speciated isotope dilution mass spectrometry (SIDMS), as described in the EPA Method 6800 (update V), was implemented with ion-exchange chromatography inductively coupled plasma mass spectrometry (IC-ICP-MS). Method 6800 uniquely enables tracking and correcting for the bidirectional chromium interspecies conversions that occur during extraction and sample handling prior to instrumental analysis. Mass balance results indicated that the off-the-shelf dietary supplements analyzed during this study contained hexavalent chromium ranging from &lt;DL (detection limit) to 122.4 ± 13.0 ?g/g, which corresponds to concentrations from below detection levels to up to 16% of the total chromium content. This type of variation in the final products raises public health issues and points to a need to use a robust method that can accurately and reliably make species measurements including correcting for species conversions."
2225023,López-García et al. 2013,Ultrasound-assisted dispersive liquid-liquid microextraction for the speciation of traces of chromium using electrothermal atomic absorption spectrometry,"A microextraction procedure for the speciation of very low concentrations (0.005-0.2 µg L(-1)) of chromium is discussed. To the aqueous sample (10 mL), diluted hydrochloric acid, sodium chloride and a small amount of tributylphosphate (80 µL) are incorporated, and the mixture is submitted to ultrasounds for 10 min. The organic phase recovered after centrifuging is injected into the electrothermal atomizer, and the signal due to hexavalent chromium obtained. The repetition of the procedure using another aliquot in which all the chromium present is oxidized to Cr (VI) allows the Cr(III) content to be obtained by difference. The enrichment factor is 240 and the detection limit 0.002 µg L(-1) chromium. The relative standard deviation for ten consecutive microextractions of a 0.1 µg L(-1) chromium solution is close to 8%. The procedure is applied to waters and to the leachates obtained from low cost toys made of plastic materials.","Ultrasound-assisted dispersive liquid-liquid microextraction for the speciation of traces of chromium using electrothermal atomic absorption spectrometry Abs: A microextraction procedure for the speciation of very low concentrations (0.005-0.2 µg L(-1)) of chromium is discussed. To the aqueous sample (10 mL), diluted hydrochloric acid, sodium chloride and a small amount of tributylphosphate (80 µL) are incorporated, and the mixture is submitted to ultrasounds for 10 min. The organic phase recovered after centrifuging is injected into the electrothermal atomizer, and the signal due to hexavalent chromium obtained. The repetition of the procedure using another aliquot in which all the chromium present is oxidized to Cr (VI) allows the Cr(III) content to be obtained by difference. The enrichment factor is 240 and the detection limit 0.002 µg L(-1) chromium. The relative standard deviation for ten consecutive microextractions of a 0.1 µg L(-1) chromium solution is close to 8%. The procedure is applied to waters and to the leachates obtained from low cost toys made of plastic materials."
2225022,Welsh et al. 2013,"Novel spot tests for detecting the presence of zinc sulfate in urine, a newly introduced urinary adulterant to invalidate drugs of abuse testing","<strong>OBJECTIVES: </strong>To find a suitable method for detecting zinc sulfate in adulterated urine.<br /><br /><strong>METHODS: </strong>Two rapid spot tests to detect the presence of zinc sulfate in urine were developed.<br /><br /><strong>RESULTS: </strong>Addition of 3 to 4 drops of 1N sodium hydroxide solution to approximately 1 mL of urine containing zinc sulfate led to the formation of a white precipitate, which was soluble in excess sodium hydroxide. In the second spot test, addition of 3 to 4 drops of 1% sodium chromate solution to 1 mL of urine containing zinc sulfate followed by the addition of 4 to 5 drops of 1N sodium hydroxide led to formation of a yellow precipitate (zinc chromate). Detection limit of these visual spot tests was 10 mg/mL of zinc sulfate in urine. Twenty drug-free urine specimens and urine containing high amounts of sugar or reducing substances were tested with no false-positive spot test results observed. However, if lead is present in high amounts in urine, it may cause false-positive spot test results. When aliquots of urine controls for drugs of abuse testing were supplemented with different amounts of zinc sulfate, false-negative drug test results were observed except for amphetamine. Zinc sulfate also falsely reduced measured urine alcohol level in urine.<br /><br /><strong>CONCLUSIONS: </strong>Zinc sulfate can invalidate urine drug and alcohol testing but can be detected using the novel spot tests developed.","Novel spot tests for detecting the presence of zinc sulfate in urine, a newly introduced urinary adulterant to invalidate drugs of abuse testing Abs: <strong>OBJECTIVES: </strong>To find a suitable method for detecting zinc sulfate in adulterated urine.<br /><br /><strong>METHODS: </strong>Two rapid spot tests to detect the presence of zinc sulfate in urine were developed.<br /><br /><strong>RESULTS: </strong>Addition of 3 to 4 drops of 1N sodium hydroxide solution to approximately 1 mL of urine containing zinc sulfate led to the formation of a white precipitate, which was soluble in excess sodium hydroxide. In the second spot test, addition of 3 to 4 drops of 1% sodium chromate solution to 1 mL of urine containing zinc sulfate followed by the addition of 4 to 5 drops of 1N sodium hydroxide led to formation of a yellow precipitate (zinc chromate). Detection limit of these visual spot tests was 10 mg/mL of zinc sulfate in urine. Twenty drug-free urine specimens and urine containing high amounts of sugar or reducing substances were tested with no false-positive spot test results observed. However, if lead is present in high amounts in urine, it may cause false-positive spot test results. When aliquots of urine controls for drugs of abuse testing were supplemented with different amounts of zinc sulfate, false-negative drug test results were observed except for amphetamine. Zinc sulfate also falsely reduced measured urine alcohol level in urine.<br /><br /><strong>CONCLUSIONS: </strong>Zinc sulfate can invalidate urine drug and alcohol testing but can be detected using the novel spot tests developed."
2225021,Baumann et al. 2014,Adaptation of the Daphnia sp. acute toxicity test: miniaturization and prolongation for the testing of nanomaterials,"Manufacturing of nanomaterials (NMs) is often complex and expensive, and their environmental risks are poorly understood or even unknown. An economization of testing NMs is therefore desirable, which can be achieved by miniaturizing test systems. However, the downsizing of test vessels and volumes can enlarge the surface/volume ratio (SVR) which in turn can affect the bioavailable concentration of adsorbing substances like NMs. The present study focused on the miniaturization of the acute toxicity test with Daphnia magna. The adaptations were verified with three reference substances, the non-adsorbing potassium dichromate (K2Cr2O7) and as potentially highly-adsorbing substances silver nanoparticles (AgNPs) and silver nitrate (AgNO3). The miniaturized test was conducted in 24-well microtiter plates (MT) and simultaneously compared to the OECD standard test (ST). Furthermore, the test duration was prolonged from 48 to 96 h since NMs tend to show effects only after extended exposure. The toxicity of K2Cr2O7 and AgNPs continued to increase within the prolonged test span. The test comparisons with K2Cr2O7 did not reveal any significant differences between ST and MT. AgNO3 toxicity was significantly decreased in MT compared to ST due to the enlarged SVR. The toxicity of AgNPs in MT after 24 h was equal to ST. Contrary to our expectations an exposure longer than 24 h resulted in an increase of AgNP toxicity in MT, possibly due to enhanced dissolution of silver. Microtiter plates are appropriate alternative test vessels for the Daphnia sp. acute toxicity test; thus, its miniaturization is feasible. The enlarged SVR has to be taken into account since it can affect the toxicity of potentially adsorbing substances. Furthermore, the standard test duration of 48 h might underestimate the toxicity of many substances, especially of NMs.","Adaptation of the Daphnia sp. acute toxicity test: miniaturization and prolongation for the testing of nanomaterials Abs: Manufacturing of nanomaterials (NMs) is often complex and expensive, and their environmental risks are poorly understood or even unknown. An economization of testing NMs is therefore desirable, which can be achieved by miniaturizing test systems. However, the downsizing of test vessels and volumes can enlarge the surface/volume ratio (SVR) which in turn can affect the bioavailable concentration of adsorbing substances like NMs. The present study focused on the miniaturization of the acute toxicity test with Daphnia magna. The adaptations were verified with three reference substances, the non-adsorbing potassium dichromate (K2Cr2O7) and as potentially highly-adsorbing substances silver nanoparticles (AgNPs) and silver nitrate (AgNO3). The miniaturized test was conducted in 24-well microtiter plates (MT) and simultaneously compared to the OECD standard test (ST). Furthermore, the test duration was prolonged from 48 to 96 h since NMs tend to show effects only after extended exposure. The toxicity of K2Cr2O7 and AgNPs continued to increase within the prolonged test span. The test comparisons with K2Cr2O7 did not reveal any significant differences between ST and MT. AgNO3 toxicity was significantly decreased in MT compared to ST due to the enlarged SVR. The toxicity of AgNPs in MT after 24 h was equal to ST. Contrary to our expectations an exposure longer than 24 h resulted in an increase of AgNP toxicity in MT, possibly due to enhanced dissolution of silver. Microtiter plates are appropriate alternative test vessels for the Daphnia sp. acute toxicity test; thus, its miniaturization is feasible. The enlarged SVR has to be taken into account since it can affect the toxicity of potentially adsorbing substances. Furthermore, the standard test duration of 48 h might underestimate the toxicity of many substances, especially of NMs."
2225020,Trinh et al. 2014,Chromium stress response effect on signal transduction and expression of signaling genes in rice,"Hexavalent chromium [Cr(VI)] is a non-essential metal for normal plants and is toxic to plants at high concentrations. However, signaling pathways and molecular mechanisms of its action on cell function and gene expression remain elusive. In this study, we found that Cr(VI) induced endogenous reactive oxygen species (ROS) generation and Ca(2+) accumulation and activated NADPH oxidase and calcium-dependent protein kinase. We investigated global transcriptional changes in rice roots by microarray analysis. Gene expression profiling indicated activation of abscisic acid-, ethylene- and jasmonic acid-mediated signaling and inactivation of gibberellic acid-related pathways in Cr(VI) stress-treated rice roots. Genes encoding signaling components such as the protein kinases domain of unknown function 26, receptor-like cytoplasmic kinase, LRK10-like kinase type 2 and protein phosphatase 2C, as well as transcription factors WRKY and apetala2/ethylene response factor were predominant during Cr(VI) stress. Genes involved in vesicle trafficking were subjected to functional characterization. Pretreating rice roots with a vesicle trafficking inhibitor, brefeldin A, effectively reduced Cr(VI)-induced ROS production. Suppression of the vesicle trafficking gene, Exo70, by virus-induced gene silencing strategies revealed that vesicle trafficking is required for mediation of Cr(VI)-induced ROS production. Taken together, these findings shed light on the molecular mechanisms in signaling pathways and transcriptional regulation in response to Cr stress in plants.","Chromium stress response effect on signal transduction and expression of signaling genes in rice Abs: Hexavalent chromium [Cr(VI)] is a non-essential metal for normal plants and is toxic to plants at high concentrations. However, signaling pathways and molecular mechanisms of its action on cell function and gene expression remain elusive. In this study, we found that Cr(VI) induced endogenous reactive oxygen species (ROS) generation and Ca(2+) accumulation and activated NADPH oxidase and calcium-dependent protein kinase. We investigated global transcriptional changes in rice roots by microarray analysis. Gene expression profiling indicated activation of abscisic acid-, ethylene- and jasmonic acid-mediated signaling and inactivation of gibberellic acid-related pathways in Cr(VI) stress-treated rice roots. Genes encoding signaling components such as the protein kinases domain of unknown function 26, receptor-like cytoplasmic kinase, LRK10-like kinase type 2 and protein phosphatase 2C, as well as transcription factors WRKY and apetala2/ethylene response factor were predominant during Cr(VI) stress. Genes involved in vesicle trafficking were subjected to functional characterization. Pretreating rice roots with a vesicle trafficking inhibitor, brefeldin A, effectively reduced Cr(VI)-induced ROS production. Suppression of the vesicle trafficking gene, Exo70, by virus-induced gene silencing strategies revealed that vesicle trafficking is required for mediation of Cr(VI)-induced ROS production. Taken together, these findings shed light on the molecular mechanisms in signaling pathways and transcriptional regulation in response to Cr stress in plants."
2225019,Ratanawimarnwong et al. 2013,New membraneless vaporization unit coupled with flow systems for analysis of ethanol,"This work presents the development of a new design for a membraneless vaporization (MBL-VP) unit, called dual chamber MBL-VP for measurement of volatile compounds. With this unit, exact volumes of sample and reagent are introduced into their respective cone-shaped chambers from the base of the cones. Diffusion of volatile analyte then takes place. After an appropriate time interval, the acceptor solution is withdrawn from the chamber into the detector flow-cell, while the sample solution is withdrawn to waste. Unlike the previous MBL-VP design, problems with overflow of solutions are eliminated by precise control of the input volume to be less than the volume of the chamber. The developed flow system with the dual chamber MBL-VP unit was applied to the determination of the ethanol content of various liquid samples, using the oxidation reaction between potassium dichromate and the diffused ethanol. In addition, in order to accelerate the gas diffusion process, the donor chamber was aerated. As the result, relatively short analysis time of 144 s was achieved for ethanol content in the range of 5-50% (v/v). The proposed method was successfully validated against a gas chromatographic method for 17 alcoholic samples. Percentage recovery was in the range of 96-109%.","New membraneless vaporization unit coupled with flow systems for analysis of ethanol Abs: This work presents the development of a new design for a membraneless vaporization (MBL-VP) unit, called dual chamber MBL-VP for measurement of volatile compounds. With this unit, exact volumes of sample and reagent are introduced into their respective cone-shaped chambers from the base of the cones. Diffusion of volatile analyte then takes place. After an appropriate time interval, the acceptor solution is withdrawn from the chamber into the detector flow-cell, while the sample solution is withdrawn to waste. Unlike the previous MBL-VP design, problems with overflow of solutions are eliminated by precise control of the input volume to be less than the volume of the chamber. The developed flow system with the dual chamber MBL-VP unit was applied to the determination of the ethanol content of various liquid samples, using the oxidation reaction between potassium dichromate and the diffused ethanol. In addition, in order to accelerate the gas diffusion process, the donor chamber was aerated. As the result, relatively short analysis time of 144 s was achieved for ethanol content in the range of 5-50% (v/v). The proposed method was successfully validated against a gas chromatographic method for 17 alcoholic samples. Percentage recovery was in the range of 96-109%."
2225018,Zhivin et al. 2013,Impact of chemical exposure on cancer mortality in a French cohort of uranium processing workers,"<strong>BACKGROUND: </strong>Nuclear workers may be exposed to a variety of chemical hazards, in addition to radiation. We examined the effect of chemical exposures on cancer mortality among French uranium processing workers at the AREVA NC Pierrelatte facility.<br /><br /><strong>METHODS: </strong>A cohort of 2,897 uranium processing workers employed for at least 6 months was followed from 1968 through 2006. Exposure to uranium and potentially carcinogenic chemicals was assessed with a plant-specific job-exposure matrix. Mortality hazard ratios (HRs) for cancers of the lung, lymphohematopoietic system, kidney and bladder, brain and central nervous system (BCNS), and prostate were estimated for each specific chemical exposure, with Cox regression models stratified for sex and calendar period and adjusted for socioeconomic status. Additional adjustments enabled us to examine the effect of co-exposure to uranium and other chemicals.<br /><br /><strong>RESULTS: </strong>Exposure to aromatic solvents was associated with increased risk of BCNS malignancies after adjustment for other chemicals (HR=6.53, 95% CI=1.14-37.41; n=6) and for other chemicals and uranium (HR=7.26, 95% CI=0.90-58.19) in the annual exposure status model. Selected groups of lymphohematopoietic cancers were found associated with solvent exposure. Inconclusive results were found regarding chromium (VI) exposure, since only 2 workers died from lung cancer among 109 exposed.<br /><br /><strong>CONCLUSION: </strong>Based on our pilot study, it seemed important to take into account chemical exposures in the analyses of cancer mortality among French uranium processing workers.","Impact of chemical exposure on cancer mortality in a French cohort of uranium processing workers Abs: <strong>BACKGROUND: </strong>Nuclear workers may be exposed to a variety of chemical hazards, in addition to radiation. We examined the effect of chemical exposures on cancer mortality among French uranium processing workers at the AREVA NC Pierrelatte facility.<br /><br /><strong>METHODS: </strong>A cohort of 2,897 uranium processing workers employed for at least 6 months was followed from 1968 through 2006. Exposure to uranium and potentially carcinogenic chemicals was assessed with a plant-specific job-exposure matrix. Mortality hazard ratios (HRs) for cancers of the lung, lymphohematopoietic system, kidney and bladder, brain and central nervous system (BCNS), and prostate were estimated for each specific chemical exposure, with Cox regression models stratified for sex and calendar period and adjusted for socioeconomic status. Additional adjustments enabled us to examine the effect of co-exposure to uranium and other chemicals.<br /><br /><strong>RESULTS: </strong>Exposure to aromatic solvents was associated with increased risk of BCNS malignancies after adjustment for other chemicals (HR=6.53, 95% CI=1.14-37.41; n=6) and for other chemicals and uranium (HR=7.26, 95% CI=0.90-58.19) in the annual exposure status model. Selected groups of lymphohematopoietic cancers were found associated with solvent exposure. Inconclusive results were found regarding chromium (VI) exposure, since only 2 workers died from lung cancer among 109 exposed.<br /><br /><strong>CONCLUSION: </strong>Based on our pilot study, it seemed important to take into account chemical exposures in the analyses of cancer mortality among French uranium processing workers."
2225017,Colin et al. 2013,Production of bioemulsifiers by Amycolatopsis tucumanensis DSM 45259 and their potential application in remediation technologies for soils contaminated with hexavalent chromium,"In recent years, increasing interest has been shown in the use of bioemulsifiers as washing agents that can enhance desorption of soil-bound metals. However, high production costs derived from the use of expensive substrates for formulation of the fermentation media represent the main challenge for full, large-scale implementation of bioemulsifiers. This work reports on a first study of bioemulsifier production by the actinobacterium Amycolatopsis tucumanensis DSM 45259 using different carbon and nitrogen sources. Preliminary results on the potential use of these compounds as washing agents for soils contaminated with Cu(II) and Cr(VI) are also presented. The best specific production was detected using glycerol and urea as carbon and nitrogen substrates, respectively. However, with all of the substrates used during the batch assay, the bioemulsifiers showed high levels of stability at extreme conditions of pH, temperature, and salt concentration. Under the current assay conditions, the bioemulsifiers were not effective in removing Cu(II) from soil. However, they were able to mediate Cr(VI) recovery, with the removal percentage doubled compared to that seen when using deionized water. These findings appear promising for the development of remediation technologies for hexavalent chromium compounds based upon direct use of these microbial emulsifiers.","Production of bioemulsifiers by Amycolatopsis tucumanensis DSM 45259 and their potential application in remediation technologies for soils contaminated with hexavalent chromium Abs: In recent years, increasing interest has been shown in the use of bioemulsifiers as washing agents that can enhance desorption of soil-bound metals. However, high production costs derived from the use of expensive substrates for formulation of the fermentation media represent the main challenge for full, large-scale implementation of bioemulsifiers. This work reports on a first study of bioemulsifier production by the actinobacterium Amycolatopsis tucumanensis DSM 45259 using different carbon and nitrogen sources. Preliminary results on the potential use of these compounds as washing agents for soils contaminated with Cu(II) and Cr(VI) are also presented. The best specific production was detected using glycerol and urea as carbon and nitrogen substrates, respectively. However, with all of the substrates used during the batch assay, the bioemulsifiers showed high levels of stability at extreme conditions of pH, temperature, and salt concentration. Under the current assay conditions, the bioemulsifiers were not effective in removing Cu(II) from soil. However, they were able to mediate Cr(VI) recovery, with the removal percentage doubled compared to that seen when using deionized water. These findings appear promising for the development of remediation technologies for hexavalent chromium compounds based upon direct use of these microbial emulsifiers."
2225016,Chapman et al. 2013,A man with severe leg burns,"A 52-year-old Hispanic male was transported to the emergency department after sustaining severe bilateral lower extremity burns in an electroplating factory. His examination revealed circumferential burns to the lower extremities with spotting in the perineum. The epidermis was stained green and sloughed off with gentle pressure. The underlying dermis was white and non-blanching, consistent with a full thickness burn. His feet were partially protected by his work boots where he had small areas of pink, blanchable, partial thickness burns (Fig. 1). Pertinent initial studies included a lactic acid level of 3.1 mmol/L and a creatinine of 1.02 mg/dL.","A man with severe leg burns Abs: A 52-year-old Hispanic male was transported to the emergency department after sustaining severe bilateral lower extremity burns in an electroplating factory. His examination revealed circumferential burns to the lower extremities with spotting in the perineum. The epidermis was stained green and sloughed off with gentle pressure. The underlying dermis was white and non-blanching, consistent with a full thickness burn. His feet were partially protected by his work boots where he had small areas of pink, blanchable, partial thickness burns (Fig. 1). Pertinent initial studies included a lactic acid level of 3.1 mmol/L and a creatinine of 1.02 mg/dL."
2225015,Saha et al. 2013,Combination of best promoter and micellar catalyst for more than kilo-fold rate acceleration in favor of chromic acid oxidation of D-galactose to D-galactonic acid in aqueous media at room temperature,"Picolinic acid, 2,2'-bipyridine and 1,10-phenanthroline promoted Cr(VI) oxidation of D-galactose to D-galactonic acid in three representative aqueous micellar media has been studied. The anionic surfactant (SDS) accelerated the rate of reaction while the cationic surfactant (CPC) and neutral surfactant (TX-100) retarded the reaction rate. Combination of bipy and SDS is the best choice for chromic acid oxidation of D-galactose to D-galactonic acid in aqueous media although 1,10-phenanthroline is best promoter in absence of micellar catalyst.","Combination of best promoter and micellar catalyst for more than kilo-fold rate acceleration in favor of chromic acid oxidation of D-galactose to D-galactonic acid in aqueous media at room temperature Abs: Picolinic acid, 2,2'-bipyridine and 1,10-phenanthroline promoted Cr(VI) oxidation of D-galactose to D-galactonic acid in three representative aqueous micellar media has been studied. The anionic surfactant (SDS) accelerated the rate of reaction while the cationic surfactant (CPC) and neutral surfactant (TX-100) retarded the reaction rate. Combination of bipy and SDS is the best choice for chromic acid oxidation of D-galactose to D-galactonic acid in aqueous media although 1,10-phenanthroline is best promoter in absence of micellar catalyst."
2225014,Ma et al. 2014,Flow injection analysis of trace chromium (VI) in drinking water with a liquid waveguide capillary cell and spectrophotometric detection,"Hexavalent chromium (Cr(VI)) is an acknowledged hazardous material in drinking waters. As such, effective monitoring and assessment of the risks posed by Cr(VI) are important analytical objectives for both human health and environmental science. However, because of the lack of highly sensitive, rapid, and simple procedures, a relatively limited number of studies have been carried out in this field. Here we report a simple and sensitive analytical procedure of flow injection analysis (FIA) for sub-nanomolar Cr(VI) in drinking water samples with a liquid core waveguide capillary cell (LWCC). The procedure is based on a highly selective reaction between 1, 5-diphenylcarbazide and Cr(VI) under acidic conditions. The optimized experimental parameters included reagent concentrations, injection volume, length of mixing coil, and flow rate. Measurements at 540 nm, and a 650-nm reference wavelength, produced a 0.12-nM detection limit. Relative standard deviations for 1, 2, and 10 nM samples were 5.6, 3.6, and 0.72 % (n?=?9), and the analysis time was &lt;2 min sample(-1). The effects of salinity and interfering ions, especially Fe(III), were evaluated. Using the FIA-LWCC method, different sources of bottled waters and tap waters were examined. The Cr(VI) concentrations of the bottled waters ranged from the detection limit to ?20 nM, and tap waters collected from the same community supply had Cr(VI) concentration around 14 nM.","Flow injection analysis of trace chromium (VI) in drinking water with a liquid waveguide capillary cell and spectrophotometric detection Abs: Hexavalent chromium (Cr(VI)) is an acknowledged hazardous material in drinking waters. As such, effective monitoring and assessment of the risks posed by Cr(VI) are important analytical objectives for both human health and environmental science. However, because of the lack of highly sensitive, rapid, and simple procedures, a relatively limited number of studies have been carried out in this field. Here we report a simple and sensitive analytical procedure of flow injection analysis (FIA) for sub-nanomolar Cr(VI) in drinking water samples with a liquid core waveguide capillary cell (LWCC). The procedure is based on a highly selective reaction between 1, 5-diphenylcarbazide and Cr(VI) under acidic conditions. The optimized experimental parameters included reagent concentrations, injection volume, length of mixing coil, and flow rate. Measurements at 540 nm, and a 650-nm reference wavelength, produced a 0.12-nM detection limit. Relative standard deviations for 1, 2, and 10 nM samples were 5.6, 3.6, and 0.72 % (n?=?9), and the analysis time was &lt;2 min sample(-1). The effects of salinity and interfering ions, especially Fe(III), were evaluated. Using the FIA-LWCC method, different sources of bottled waters and tap waters were examined. The Cr(VI) concentrations of the bottled waters ranged from the detection limit to ?20 nM, and tap waters collected from the same community supply had Cr(VI) concentration around 14 nM."
2225013,Thompson et al. 2014,A chronic oral reference dose for hexavalent chromium-induced intestinal cancer,"High concentrations of hexavalent chromium [Cr(VI)] in drinking water induce villous cytotoxicity and compensatory crypt hyperplasia in the small intestines of mice (but not rats). Lifetime exposure to such cytotoxic concentrations increases intestinal neoplasms in mice, suggesting that the mode of action for Cr(VI)-induced intestinal tumors involves chronic wounding and compensatory cell proliferation of the intestine. Therefore, we developed a chronic oral reference dose (RfD) designed to be protective of intestinal damage and thus intestinal cancer. A physiologically based pharmacokinetic model for chromium in mice was used to estimate the amount of Cr(VI) entering each intestinal tissue section (duodenum, jejunum and ileum) from the lumen per day (normalized to intestinal tissue weight). These internal dose metrics, together with corresponding incidences for diffuse hyperplasia, were used to derive points of departure using benchmark dose modeling and constrained nonlinear regression. Both modeling techniques resulted in similar points of departure, which were subsequently converted to human equivalent doses using a human physiologically based pharmacokinetic model. Applying appropriate uncertainty factors, an RfD of 0.006?mg?kg(-1) ?day(-1) was derived for diffuse hyperplasia-an effect that precedes tumor formation. This RfD is protective of both noncancer and cancer effects in the small intestine and corresponds to a safe drinking water equivalent level of 210 µg l(-1) . This concentration is higher than the current federal maximum contaminant level for total Cr (100 µg l(-1) ) and well above levels of Cr(VI) in US drinking water supplies (typically???5 µg l(-1) ). © 2013 The Authors. Journal of Applied Toxicology published by John Wiley & Sons, Ltd.","A chronic oral reference dose for hexavalent chromium-induced intestinal cancer Abs: High concentrations of hexavalent chromium [Cr(VI)] in drinking water induce villous cytotoxicity and compensatory crypt hyperplasia in the small intestines of mice (but not rats). Lifetime exposure to such cytotoxic concentrations increases intestinal neoplasms in mice, suggesting that the mode of action for Cr(VI)-induced intestinal tumors involves chronic wounding and compensatory cell proliferation of the intestine. Therefore, we developed a chronic oral reference dose (RfD) designed to be protective of intestinal damage and thus intestinal cancer. A physiologically based pharmacokinetic model for chromium in mice was used to estimate the amount of Cr(VI) entering each intestinal tissue section (duodenum, jejunum and ileum) from the lumen per day (normalized to intestinal tissue weight). These internal dose metrics, together with corresponding incidences for diffuse hyperplasia, were used to derive points of departure using benchmark dose modeling and constrained nonlinear regression. Both modeling techniques resulted in similar points of departure, which were subsequently converted to human equivalent doses using a human physiologically based pharmacokinetic model. Applying appropriate uncertainty factors, an RfD of 0.006?mg?kg(-1) ?day(-1) was derived for diffuse hyperplasia-an effect that precedes tumor formation. This RfD is protective of both noncancer and cancer effects in the small intestine and corresponds to a safe drinking water equivalent level of 210 µg l(-1) . This concentration is higher than the current federal maximum contaminant level for total Cr (100 µg l(-1) ) and well above levels of Cr(VI) in US drinking water supplies (typically???5 µg l(-1) ). © 2013 The Authors. Journal of Applied Toxicology published by John Wiley & Sons, Ltd."
2225012,Jardine et al. 2013,Influence of soil geochemical and physical properties on chromium(VI) sorption and bioaccessibility,"The Department of Defense (DoD) is faced with the daunting task of possible remediation of numerous soil-Cr(VI) contaminated sites throughout the continental U.S. The primary risk driver at these sites is hand-to-mouth ingestion of contaminated soil by children. In the following study we investigate the impact of soil geochemical and physical properties on the sorption and bioaccessibility of Cr(VI) in a vast array of soils relevant to neighboring DoD sites. For the 35 soils used in this study, A-horizon soils typically sorbed significantly more Cr(VI) relative to B-horizon soils. Multiple linear regression analysis suggested that Cr(VI) sorption increased with increasing soil total organic C (TOC) and decreasing soil pH. The bioaccessibility of total Cr (CrT) and Cr(VI) on the soils decreased with increasing soil TOC content. As the soil TOC content approached 0.4%, the bioaccessibility of soil bound Cr systematically decreased from approximately 65 to 10%. As the soil TOC content increased from 0.4 to 4%, the bioaccessibility of Cr(VI) and CrT remained relatively constant at approximately 4% and 10%, respectively. X-ray absorption near edge structure (XANES) spectroscopy suggested that Cr(VI) reduction to Cr(III) was prevalent and that the redox transformation of Cr(VI) increased with increasing soil TOC. XANES confirmed that nearly all bioaccessible soil Cr was the Cr(VI) moiety. Multiple linear regression analysis suggested that the bioaccessibility of Cr(VI) and its reduced counterpart Cr(III), decreased with increasing soil TOC and increasing soil pH. This is consistent with the observation that the reduction reaction and formation of Cr(III) increased with increasing soil TOC and that Cr(III) was significantly less bioaccessible relative to Cr(VI). The model was found to adequately describe CrT bioaccessibility in soils from DoD facilities where Cr(VI) contaminated sites were present. The results of this study illustrate the importance of soil properties on Cr(VI) sorption and bioassessability and help define what soil types have the greatest risk associated with Cr(VI) exposure.","Influence of soil geochemical and physical properties on chromium(VI) sorption and bioaccessibility Abs: The Department of Defense (DoD) is faced with the daunting task of possible remediation of numerous soil-Cr(VI) contaminated sites throughout the continental U.S. The primary risk driver at these sites is hand-to-mouth ingestion of contaminated soil by children. In the following study we investigate the impact of soil geochemical and physical properties on the sorption and bioaccessibility of Cr(VI) in a vast array of soils relevant to neighboring DoD sites. For the 35 soils used in this study, A-horizon soils typically sorbed significantly more Cr(VI) relative to B-horizon soils. Multiple linear regression analysis suggested that Cr(VI) sorption increased with increasing soil total organic C (TOC) and decreasing soil pH. The bioaccessibility of total Cr (CrT) and Cr(VI) on the soils decreased with increasing soil TOC content. As the soil TOC content approached 0.4%, the bioaccessibility of soil bound Cr systematically decreased from approximately 65 to 10%. As the soil TOC content increased from 0.4 to 4%, the bioaccessibility of Cr(VI) and CrT remained relatively constant at approximately 4% and 10%, respectively. X-ray absorption near edge structure (XANES) spectroscopy suggested that Cr(VI) reduction to Cr(III) was prevalent and that the redox transformation of Cr(VI) increased with increasing soil TOC. XANES confirmed that nearly all bioaccessible soil Cr was the Cr(VI) moiety. Multiple linear regression analysis suggested that the bioaccessibility of Cr(VI) and its reduced counterpart Cr(III), decreased with increasing soil TOC and increasing soil pH. This is consistent with the observation that the reduction reaction and formation of Cr(III) increased with increasing soil TOC and that Cr(III) was significantly less bioaccessible relative to Cr(VI). The model was found to adequately describe CrT bioaccessibility in soils from DoD facilities where Cr(VI) contaminated sites were present. The results of this study illustrate the importance of soil properties on Cr(VI) sorption and bioassessability and help define what soil types have the greatest risk associated with Cr(VI) exposure."
2225011,Weldy et al. 2013,Selective and sensitive detection of chromium(VI) in waters using electrospray ionization mass spectrometry,"From 2000 through 2011, there were 14 criminal cases of violations of the Clean Water Act involving the discharge of chromium, a toxic heavy metal, into drinking and surface water sources. As chromium(VI), a potential carcinogen present in the environment, represents a significant safety concern, it is currently the subject of an EPA health risk assessment. Therefore, sensitive and selective detection of this species is highly desired. This study reports the analysis of chromium(VI) in water samples by electrospray ionization mass spectrometry (ESI-MS) following its reduction and complexation with ammonium pyrrolidinedithiocarbamate (APDC). The reduction and subsequent complexation produce a characteristic [Cr(III)O]-PDC complex which can be detected as a protonated ion of m/z 507 in the positive ion mode. The detection is selective to chromium(VI) under acidic pH, even in the presence of chromium(III) and other metal ions, providing high specificity. Different water samples were examined, including deionized, tap, and river waters, and sensitive detection was achieved. In the case of deionized water, quantification over the concentration range of 3.7 to 148ppb gave an excellent correlation coefficient of 0.9904 using the enhanced MS mode scan. Using the single-reaction monitoring (SRM) mode (monitoring the characteristic fragmentation of m/z 507 to m/z 360), the limit of detection (LOD) was found to be 0.25ppb. The LOD of chromium(VI) for both tap and river water samples was determined to be 2.0ppb. A preconcentration strategy using simple vacuum evaporation of the aqueous sample was shown to further improve the ESI signal by 15 fold. This method, with high sensitivity and selectivity, should provide a timely solution for the real-world analysis of toxic chromium(VI).","Selective and sensitive detection of chromium(VI) in waters using electrospray ionization mass spectrometry Abs: From 2000 through 2011, there were 14 criminal cases of violations of the Clean Water Act involving the discharge of chromium, a toxic heavy metal, into drinking and surface water sources. As chromium(VI), a potential carcinogen present in the environment, represents a significant safety concern, it is currently the subject of an EPA health risk assessment. Therefore, sensitive and selective detection of this species is highly desired. This study reports the analysis of chromium(VI) in water samples by electrospray ionization mass spectrometry (ESI-MS) following its reduction and complexation with ammonium pyrrolidinedithiocarbamate (APDC). The reduction and subsequent complexation produce a characteristic [Cr(III)O]-PDC complex which can be detected as a protonated ion of m/z 507 in the positive ion mode. The detection is selective to chromium(VI) under acidic pH, even in the presence of chromium(III) and other metal ions, providing high specificity. Different water samples were examined, including deionized, tap, and river waters, and sensitive detection was achieved. In the case of deionized water, quantification over the concentration range of 3.7 to 148ppb gave an excellent correlation coefficient of 0.9904 using the enhanced MS mode scan. Using the single-reaction monitoring (SRM) mode (monitoring the characteristic fragmentation of m/z 507 to m/z 360), the limit of detection (LOD) was found to be 0.25ppb. The LOD of chromium(VI) for both tap and river water samples was determined to be 2.0ppb. A preconcentration strategy using simple vacuum evaporation of the aqueous sample was shown to further improve the ESI signal by 15 fold. This method, with high sensitivity and selectivity, should provide a timely solution for the real-world analysis of toxic chromium(VI)."
2225010,Madhavi et al. 2013,Application of phytogenic zerovalent iron nanoparticles in the adsorption of hexavalent chromium,"Zerovalent iron nanoparticles (ZVNI) were synthesized using a rapid, single step and completely green synthetic method from the leaf extracts of Eucalyptus globules and were characterized using the techniques Scanning Electron Microscopy (SEM), UV-Vis Spectroscopy, Fourier Transform-Infrared Spectroscopy (FT-IR), X-ray Diffraction (XRD) and Zeta potential measurement. The FT-IR analysis reveals that the polyphenolic compounds present in the leaf extract may be responsible for the reduction and stabilization of the ZVNI. These nanoparticles were utilized for the adsorption of hexavalent chromium (Cr (VI)) and the concentration of Cr (VI) was determined using UV-Vis spectrometer after treating with ZVNI. Response and surface contour plots were drawn with the help of Mini-tab software to explain the adsorption of Cr (VI). The adsorption efficiency of Cr (VI) reaches to the highest value (98.1%) when the reaction time was about 30 min. and the ZVNI dosage was 0.8 g/L. The effective parameters such as adsorbent (ZVNI) dosage, initial Cr (VI) concentration and the kinetics were also examined.","Application of phytogenic zerovalent iron nanoparticles in the adsorption of hexavalent chromium Abs: Zerovalent iron nanoparticles (ZVNI) were synthesized using a rapid, single step and completely green synthetic method from the leaf extracts of Eucalyptus globules and were characterized using the techniques Scanning Electron Microscopy (SEM), UV-Vis Spectroscopy, Fourier Transform-Infrared Spectroscopy (FT-IR), X-ray Diffraction (XRD) and Zeta potential measurement. The FT-IR analysis reveals that the polyphenolic compounds present in the leaf extract may be responsible for the reduction and stabilization of the ZVNI. These nanoparticles were utilized for the adsorption of hexavalent chromium (Cr (VI)) and the concentration of Cr (VI) was determined using UV-Vis spectrometer after treating with ZVNI. Response and surface contour plots were drawn with the help of Mini-tab software to explain the adsorption of Cr (VI). The adsorption efficiency of Cr (VI) reaches to the highest value (98.1%) when the reaction time was about 30 min. and the ZVNI dosage was 0.8 g/L. The effective parameters such as adsorbent (ZVNI) dosage, initial Cr (VI) concentration and the kinetics were also examined."
2225009,Yang et al. 2013,Analysis of hexavalent chromium in Colla corii asini with on-line sample pretreatment valve-switching ion chromatography,"An ion chromatography (IC) system with on-line sample pretreatment using valve-switching technique was developed for the determination of hexavalent chromium (Cr(VI)) in Colla corii asini. Colla corii asini is a complicated sample with organics as main matrix. In this work, a polymer-based reversed-phase column was used as a pretreatment column. Via valve-switching technique, sample solution with target ions were eluted from a collection loop to analytical columns, with matrix eliminated on-line. Under the optimized separation conditions, the method showed good linearity (r=0.9998) in the range of 0.004-1.0mg/L and satisfactory repeatability (RSD&lt;3%, n=6). The limit of detection (LOD) was 1.4?g/L (S/N=3). The average spiked recoveries of Cr(VI) were 93.4-102.0%. The result showed that the on-line sample pretreatment IC system was convenient and practical for the determination of trace Cr(VI) in Colla corii asini samples.","Analysis of hexavalent chromium in Colla corii asini with on-line sample pretreatment valve-switching ion chromatography Abs: An ion chromatography (IC) system with on-line sample pretreatment using valve-switching technique was developed for the determination of hexavalent chromium (Cr(VI)) in Colla corii asini. Colla corii asini is a complicated sample with organics as main matrix. In this work, a polymer-based reversed-phase column was used as a pretreatment column. Via valve-switching technique, sample solution with target ions were eluted from a collection loop to analytical columns, with matrix eliminated on-line. Under the optimized separation conditions, the method showed good linearity (r=0.9998) in the range of 0.004-1.0mg/L and satisfactory repeatability (RSD&lt;3%, n=6). The limit of detection (LOD) was 1.4?g/L (S/N=3). The average spiked recoveries of Cr(VI) were 93.4-102.0%. The result showed that the on-line sample pretreatment IC system was convenient and practical for the determination of trace Cr(VI) in Colla corii asini samples."
2225008,Trögl et al. 2013,A single-parameter logistic equation for fitting concentration-response curves from standard acute ecotoxicity assays,A set of 69 concentration-response curves from 5 acute ecotoxicity assays was fitted with a 2-parameter logistic equation. High correlation between values of regression parameters suggested similar slopes of the curves. This enabled derivation of the empirical single-parameter logistic equation with the sole median effective concentration (EC50) parameter. Such an equation might be useful in the evaluation of lower-quality (preliminary) experimental data and for the reduction of the number of test organisms and of testing costs.,A single-parameter logistic equation for fitting concentration-response curves from standard acute ecotoxicity assays Abs: A set of 69 concentration-response curves from 5 acute ecotoxicity assays was fitted with a 2-parameter logistic equation. High correlation between values of regression parameters suggested similar slopes of the curves. This enabled derivation of the empirical single-parameter logistic equation with the sole median effective concentration (EC50) parameter. Such an equation might be useful in the evaluation of lower-quality (preliminary) experimental data and for the reduction of the number of test organisms and of testing costs.
2225007,Ali et al. 2013,Alleviation of chromium toxicity by hydrogen sulfide in barley,"A hydroponic experiment was carried out to examine the effect of hydrogen sulfide (H2 S) in alleviating chromium (Cr) stress in barley. A 2-factorial design with 6 replications was selected, including 3 levels of NaHS (0 ?M, 100 ?M, and 200 ?M) and 2 levels of Cr (0 ?M and 100 ?M) as treatments. The results showed that NaHS addition enhances plant growth and photosynthesis slightly compared with the control. Moreover, NaHS alleviated the inhibition in plant growth and photosynthesis by Cr stress. Higher levels of NaHS exhibited more pronounced effects in reducing Cr concentrations in roots, shoots, and leaves. Ultrastructural examination of plant cells supported the facts by indication of visible alleviation of cell disorders in both root and leaf with exogenous application of NaHS. An increased number of plastoglobuli, disintegration, and disappearance of thylakoid membranes and starch granules were visualized inside the chloroplast of Cr-stressed plants. Starch accumulation in the chloroplasts was also noticed in the Cr-treated cells, with the effect being much less in Cr + NaHS-treated plants. Hence, it is concluded that H2 S produced from NaHS can improve plant tolerance under Cr stress.","Alleviation of chromium toxicity by hydrogen sulfide in barley Abs: A hydroponic experiment was carried out to examine the effect of hydrogen sulfide (H2 S) in alleviating chromium (Cr) stress in barley. A 2-factorial design with 6 replications was selected, including 3 levels of NaHS (0 ?M, 100 ?M, and 200 ?M) and 2 levels of Cr (0 ?M and 100 ?M) as treatments. The results showed that NaHS addition enhances plant growth and photosynthesis slightly compared with the control. Moreover, NaHS alleviated the inhibition in plant growth and photosynthesis by Cr stress. Higher levels of NaHS exhibited more pronounced effects in reducing Cr concentrations in roots, shoots, and leaves. Ultrastructural examination of plant cells supported the facts by indication of visible alleviation of cell disorders in both root and leaf with exogenous application of NaHS. An increased number of plastoglobuli, disintegration, and disappearance of thylakoid membranes and starch granules were visualized inside the chloroplast of Cr-stressed plants. Starch accumulation in the chloroplasts was also noticed in the Cr-treated cells, with the effect being much less in Cr + NaHS-treated plants. Hence, it is concluded that H2 S produced from NaHS can improve plant tolerance under Cr stress."
2225006,López-García et al. 2013,Experimental evidences for a new model in the description of the adsorption-coupled reduction of Cr(VI) by protonated banana skin,"This work reports experimental evidences, not previously considered, to evaluate the Cr(VI) removal by protonated banana skin biomass. Variations in the number of hydroxyl groups, quantified by potentiometric titrations, and CO2 evolution during experiments, were attributed mainly to the oxidation of hydroxylic entities present in the studied material. The results indicate that these groups together with the carboxylic moieties are the main functionalities involved on the adsorption-coupled reduction process. The column experiment carried out provides a new approach to obtain the maximum reduction capacity of the material (3.72 mmol g(-1)). Moreover, we hereby propose a model that reports the first evidence for the instant bound of Cr(III) species to the material used, formed after the reduction of Cr(VI) present in solution. The removal process was quantified carrying out experiments under various pHs, biomass doses and Cr(VI) concentrations, and the mechanism underlying chromium removal was identified.","Experimental evidences for a new model in the description of the adsorption-coupled reduction of Cr(VI) by protonated banana skin Abs: This work reports experimental evidences, not previously considered, to evaluate the Cr(VI) removal by protonated banana skin biomass. Variations in the number of hydroxyl groups, quantified by potentiometric titrations, and CO2 evolution during experiments, were attributed mainly to the oxidation of hydroxylic entities present in the studied material. The results indicate that these groups together with the carboxylic moieties are the main functionalities involved on the adsorption-coupled reduction process. The column experiment carried out provides a new approach to obtain the maximum reduction capacity of the material (3.72 mmol g(-1)). Moreover, we hereby propose a model that reports the first evidence for the instant bound of Cr(III) species to the material used, formed after the reduction of Cr(VI) present in solution. The removal process was quantified carrying out experiments under various pHs, biomass doses and Cr(VI) concentrations, and the mechanism underlying chromium removal was identified."
2225005,Chen et al. 2013,Preparation and characterization of magnetic Fe3O 4/CNT nanoparticles by RPO method to enhance the efficient removal of Cr(VI),"This work described a novel method for the synthesis of high-ferromagnetism nanoparticles (Fe3O4/CNTs) to efficiently remove Cr(VI) from aqueous solution. The Fe3O4/carbon nanotubes (CNTs) were prepared by in situ reduction with post-oxidation method by using cheap and environmentally friendly precursor under mild condition. Magnetic hysteresis loops revealed that Fe3O4/CNTs had superior saturation magnetization (152 emu/g), enabling the highly efficient recovery of Fe3O4/CNTs from aqueous solution by magnetic separation at low magnetic field gradients. FTIR, Raman, XPS, and TEM observations were employed to characterize the physical-chemical properties of Fe3O4/CNTs, demonstrating that CNTs were successfully coated with iron oxide matrix. The adsorption equilibrium of Cr(VI) on Fe3O4/CNTs was reached within 30 min. Langmuir, Freundlich, and Dubinin-Radushkevich isotherm were chosen to analyze the equilibrium data. The results indicated that Langmuir model can well describe the equilibrium data with the maximum adsorption capacity of 47.98 mg/g at room temperature and 83.54 mg/g at 353 K. The adsorption capacity of Fe3O4/CNTs for Cr(VI) was greatly improved as compared to raw CNTs and other similar adsorbents reported. The pseudo-second-order kinetic model provided the best description of Cr(VI) adsorption on Fe3O4/CNTs. Most importantly, possible synthesis mechanism and Cr(VI) removal mechanism were explored. The results suggest that large amounts of Cr(VI) were adsorbed on Fe3O4/CNTs surface by substituting the surface position of -OH and then reducing it to Cr(OH)3 and Cr2O3.","Preparation and characterization of magnetic Fe3O 4/CNT nanoparticles by RPO method to enhance the efficient removal of Cr(VI) Abs: This work described a novel method for the synthesis of high-ferromagnetism nanoparticles (Fe3O4/CNTs) to efficiently remove Cr(VI) from aqueous solution. The Fe3O4/carbon nanotubes (CNTs) were prepared by in situ reduction with post-oxidation method by using cheap and environmentally friendly precursor under mild condition. Magnetic hysteresis loops revealed that Fe3O4/CNTs had superior saturation magnetization (152 emu/g), enabling the highly efficient recovery of Fe3O4/CNTs from aqueous solution by magnetic separation at low magnetic field gradients. FTIR, Raman, XPS, and TEM observations were employed to characterize the physical-chemical properties of Fe3O4/CNTs, demonstrating that CNTs were successfully coated with iron oxide matrix. The adsorption equilibrium of Cr(VI) on Fe3O4/CNTs was reached within 30 min. Langmuir, Freundlich, and Dubinin-Radushkevich isotherm were chosen to analyze the equilibrium data. The results indicated that Langmuir model can well describe the equilibrium data with the maximum adsorption capacity of 47.98 mg/g at room temperature and 83.54 mg/g at 353 K. The adsorption capacity of Fe3O4/CNTs for Cr(VI) was greatly improved as compared to raw CNTs and other similar adsorbents reported. The pseudo-second-order kinetic model provided the best description of Cr(VI) adsorption on Fe3O4/CNTs. Most importantly, possible synthesis mechanism and Cr(VI) removal mechanism were explored. The results suggest that large amounts of Cr(VI) were adsorbed on Fe3O4/CNTs surface by substituting the surface position of -OH and then reducing it to Cr(OH)3 and Cr2O3."
2225004,Wu et al. 2013,Micro-electrolysis of Cr (VI) in the nanoscale zero-valent iron loaded activated carbon,"In this paper we prepared a novel material of activated carbon/nanoscale zero-valent iron (C-Fe(0)) composite. The C-Fe(0) was proved to possess large specific surface area and outstanding reducibility that result in the rapid and stable reaction with Cr (VI). The prepared composite has been examined in detail in terms of the influence of solution pH, concentration and reaction time in the Cr (VI) removal experiments. The results showed that the C-Fe(0) formed a micro-electrolysis which dominated the reaction rate. The Micro-electrolysis reaches equilibrium is ten minutes. Its reaction rate is ten times higher than that of traditional adsorption reaction, and the removal rate of Cr reaches up to 99.5%. By analyzing the obtained profiles from the cyclic voltammetry, PXRD and XPS, we demonstrate that the Cr (VI) is reduced to insoluble Cr (III) compound in the reaction.","Micro-electrolysis of Cr (VI) in the nanoscale zero-valent iron loaded activated carbon Abs: In this paper we prepared a novel material of activated carbon/nanoscale zero-valent iron (C-Fe(0)) composite. The C-Fe(0) was proved to possess large specific surface area and outstanding reducibility that result in the rapid and stable reaction with Cr (VI). The prepared composite has been examined in detail in terms of the influence of solution pH, concentration and reaction time in the Cr (VI) removal experiments. The results showed that the C-Fe(0) formed a micro-electrolysis which dominated the reaction rate. The Micro-electrolysis reaches equilibrium is ten minutes. Its reaction rate is ten times higher than that of traditional adsorption reaction, and the removal rate of Cr reaches up to 99.5%. By analyzing the obtained profiles from the cyclic voltammetry, PXRD and XPS, we demonstrate that the Cr (VI) is reduced to insoluble Cr (III) compound in the reaction."
2225003,Zhang et al. 2013,Polyaniline nanorods dotted on graphene oxide nanosheets as a novel super adsorbent for Cr(VI),Hierarchical nanocomposites of polyaniline (PANI) nanorods array on graphene oxide (GO) nanosheets are successfully obtained by dilute polymerization under -20 °C. They exhibit excellent water treatment performance with a superb removal capacity of 1149.4 mg g(-1) for Cr(VI).,Polyaniline nanorods dotted on graphene oxide nanosheets as a novel super adsorbent for Cr(VI) Abs: Hierarchical nanocomposites of polyaniline (PANI) nanorods array on graphene oxide (GO) nanosheets are successfully obtained by dilute polymerization under -20 °C. They exhibit excellent water treatment performance with a superb removal capacity of 1149.4 mg g(-1) for Cr(VI).
2225002,Li et al. 2013,N-doped porous carbon with magnetic particles formed in situ for enhanced Cr(VI) removal,"A newly designed N-doped porous carbon with magnetic nanoparticles formed in situ (RHC-mag-CN) was fabricated through simple impregnation then polymerization and calcination. The doped nitrogen in RHC-mag-CN was in the form of graphite-type layers with the composition of CN. The resultant nanocomposite maintained a high surface area of 1136 m(2) g(-1) with 18.5 wt% magnetic nanoparticles (Fe3O4 and Fe) inside, which showed a saturation magnetization (Ms) of 22 emu/g. When used as an adsorbent, the RHC-mag-CN demonstrated a very quick adsorption property for the removal of Cr(VI), during which 92% of Cr(VI) could be removed within 10 min for dilute solutions at 2 g L(-1) adsorbent dose. The high adsorption capacity (16 mg g(-1)) is related to the synergetic effects of physical adsorption from the surface area and chemical adsorption from complexation reactions between Cr(VI) and Fe3O4. Importantly, the basic CNs in RHC-mag-CN increase its negative charge density and simultaneously increase the adsorption of metallic cations, such as Cr(3+) formed in the acid solution from the reduction of Cr(VI). The formation of magnetic nanoparticles inside not only supplies complexing sites for the adsorption of Cr(VI), but also shows perfect magnetic separation performance from aqueous solution.","N-doped porous carbon with magnetic particles formed in situ for enhanced Cr(VI) removal Abs: A newly designed N-doped porous carbon with magnetic nanoparticles formed in situ (RHC-mag-CN) was fabricated through simple impregnation then polymerization and calcination. The doped nitrogen in RHC-mag-CN was in the form of graphite-type layers with the composition of CN. The resultant nanocomposite maintained a high surface area of 1136 m(2) g(-1) with 18.5 wt% magnetic nanoparticles (Fe3O4 and Fe) inside, which showed a saturation magnetization (Ms) of 22 emu/g. When used as an adsorbent, the RHC-mag-CN demonstrated a very quick adsorption property for the removal of Cr(VI), during which 92% of Cr(VI) could be removed within 10 min for dilute solutions at 2 g L(-1) adsorbent dose. The high adsorption capacity (16 mg g(-1)) is related to the synergetic effects of physical adsorption from the surface area and chemical adsorption from complexation reactions between Cr(VI) and Fe3O4. Importantly, the basic CNs in RHC-mag-CN increase its negative charge density and simultaneously increase the adsorption of metallic cations, such as Cr(3+) formed in the acid solution from the reduction of Cr(VI). The formation of magnetic nanoparticles inside not only supplies complexing sites for the adsorption of Cr(VI), but also shows perfect magnetic separation performance from aqueous solution."
2225001,Gong et al. 2013,Study of the adsorption of Cr(VI) by tannic acid immobilised powdered activated carbon from micro-polluted water in the presence of dissolved humic acid,"The adsorption of Cr(VI) (0.500 mg/L) onto food-grade tannic-acid immobilised powdered activated carbon (TA-PAC) in the presence of dissolved humic acid (DHA) was investigated at 280 K as a function of pH, along with the adsorption capacities and the adsorption isotherms for chromium ions. The results showed that the presence of DHA improved the adsorption capacities of Cr(VI) and its reduction product (Cr(III)) over a wide pH range (4.0-8.0). The main mechanism for metal-DHA complexation in the Cr(VI) system was the reduction of Cr(VI) followed by complexation between Cr(III) and DHA. The Freundlich isotherms yielded the best fits to all data (R(2)=0.9951, qm=5.639 mg/g) in the presence of DHA. The adsorption mechanisms of Cr(VI) onto TA-PAC in the presence of DHA were summarized into three categories: (i) binding by anion adsorption, (ii) Cr(VI) reduction followed by Cr(III) adsorption, and (iii) adsorption of Cr(III)-DHA complexes.","Study of the adsorption of Cr(VI) by tannic acid immobilised powdered activated carbon from micro-polluted water in the presence of dissolved humic acid Abs: The adsorption of Cr(VI) (0.500 mg/L) onto food-grade tannic-acid immobilised powdered activated carbon (TA-PAC) in the presence of dissolved humic acid (DHA) was investigated at 280 K as a function of pH, along with the adsorption capacities and the adsorption isotherms for chromium ions. The results showed that the presence of DHA improved the adsorption capacities of Cr(VI) and its reduction product (Cr(III)) over a wide pH range (4.0-8.0). The main mechanism for metal-DHA complexation in the Cr(VI) system was the reduction of Cr(VI) followed by complexation between Cr(III) and DHA. The Freundlich isotherms yielded the best fits to all data (R(2)=0.9951, qm=5.639 mg/g) in the presence of DHA. The adsorption mechanisms of Cr(VI) onto TA-PAC in the presence of DHA were summarized into three categories: (i) binding by anion adsorption, (ii) Cr(VI) reduction followed by Cr(III) adsorption, and (iii) adsorption of Cr(III)-DHA complexes."
2225000,Zhan et al. 2013,Validation and application of a thermal-optical reflectance (TOR) method for measuring black carbon in loess sediments,"Three techniques were used to measure black carbon (BC) in samples from Chinese loess-paleosol sequences. The results obtained by (1) chemo-thermal oxidation (CTO, performed two ways), (2) acid dichromate oxidation (Cr2O7), and (3) thermal-optical reflectance (TOR) were intercompared because prior studies have shown that the methods can yield disparate results. BC concentrations did vary among the methods, most likely because they measured different components of the BC continuum, but the high-temperature BC (soot) determined by CTO was correlated with the BC and soot obtained by TOR. The CTO and TOR methods both yielded statistically significant linear relationships for loess and lake sediments that had incremental additions of a standard (SRM-1649a). The results also showed that charred material was more abundant in these test sediments than soot carbon. Data for BC in Luochuan loess generated using TOR showed a trend similar to that of magnetic susceptibility, that is, high BC and large susceptibilities during the last interglacial and low values for both variables in the last glacial. The results thus indicate that the TOR method is well suited for studies of sedimentary materials and that more biomass burned during the last interglacial than in the last glacial.","Validation and application of a thermal-optical reflectance (TOR) method for measuring black carbon in loess sediments Abs: Three techniques were used to measure black carbon (BC) in samples from Chinese loess-paleosol sequences. The results obtained by (1) chemo-thermal oxidation (CTO, performed two ways), (2) acid dichromate oxidation (Cr2O7), and (3) thermal-optical reflectance (TOR) were intercompared because prior studies have shown that the methods can yield disparate results. BC concentrations did vary among the methods, most likely because they measured different components of the BC continuum, but the high-temperature BC (soot) determined by CTO was correlated with the BC and soot obtained by TOR. The CTO and TOR methods both yielded statistically significant linear relationships for loess and lake sediments that had incremental additions of a standard (SRM-1649a). The results also showed that charred material was more abundant in these test sediments than soot carbon. Data for BC in Luochuan loess generated using TOR showed a trend similar to that of magnetic susceptibility, that is, high BC and large susceptibilities during the last interglacial and low values for both variables in the last glacial. The results thus indicate that the TOR method is well suited for studies of sedimentary materials and that more biomass burned during the last interglacial than in the last glacial."
2215695,Paul and  Shakya 2013,"Arsenic, chromium and NaCl induced artemisinin biosynthesis in Artemisia annua L.: a valuable antimalarial plant","Effect of As(III), Cr(VI) and NaCl on plant growth, antioxidant enzymes, SOD, TBRAS, protein, cDNA amplification of key genes of artemisinin pathway and artemisinin biosynthesis have been investigated to explore the actual changes in total herb and artemisinin yield in a crop cycle of Artemisia annua. Enhanced TBARS and SOD activity (4 U mg?¹), decreased catalase activity and total cholorophyll content were observed under metal(loid) and NaCl stress. Accumulation of As (III; µg mg?¹ DW) was higher in roots (10.75±0.00) than shoot (0.43±0.00) at 10 µg ml?¹. While Cr(VI; µg ml?¹ DW) accumulated more in shoots (37±9.6, 41.1±7.2 and 52.71±19.6). cDNA template of these treated plants along with control were amplified with HMGR, ADS and CYP71AV1 genes (artemisinin biosynthetic pathway genes); showed very low expression with Cr(VI) while As(III) (5 and 7.5 µg ml?¹) showed higher expression than control. The results obtained from this study suggest that A. annua can grow well with favoring artemisinin biosynthesis with treatment of As(III) 5, 7.5 µg ml?¹ and NaCl, while 10 µg ml?¹ As(III) and all doses of Cr(VI) affect artemisinin synthesis. Finally some evidence also suggests that As(III), Cr(VI) and NaCl induces stress affects on total herb yield of plant.","Arsenic, chromium and NaCl induced artemisinin biosynthesis in Artemisia annua L.: a valuable antimalarial plant Abs: Effect of As(III), Cr(VI) and NaCl on plant growth, antioxidant enzymes, SOD, TBRAS, protein, cDNA amplification of key genes of artemisinin pathway and artemisinin biosynthesis have been investigated to explore the actual changes in total herb and artemisinin yield in a crop cycle of Artemisia annua. Enhanced TBARS and SOD activity (4 U mg?¹), decreased catalase activity and total cholorophyll content were observed under metal(loid) and NaCl stress. Accumulation of As (III; µg mg?¹ DW) was higher in roots (10.75±0.00) than shoot (0.43±0.00) at 10 µg ml?¹. While Cr(VI; µg ml?¹ DW) accumulated more in shoots (37±9.6, 41.1±7.2 and 52.71±19.6). cDNA template of these treated plants along with control were amplified with HMGR, ADS and CYP71AV1 genes (artemisinin biosynthetic pathway genes); showed very low expression with Cr(VI) while As(III) (5 and 7.5 µg ml?¹) showed higher expression than control. The results obtained from this study suggest that A. annua can grow well with favoring artemisinin biosynthesis with treatment of As(III) 5, 7.5 µg ml?¹ and NaCl, while 10 µg ml?¹ As(III) and all doses of Cr(VI) affect artemisinin synthesis. Finally some evidence also suggests that As(III), Cr(VI) and NaCl induces stress affects on total herb yield of plant."
2149193,Matos et al. 2013,Mechanisms of kidney toxicity for chromium- and arsenic-based preservatives: Potential involvement of a pro-oxidative pathway,"Metals have been extensively used for the preservation of wood. Among metallic conservatives, mixtures of chromated copper arsenate (CCA) were thoroughly used. However, the release and consequent mobilization of such compounds by biota, may culminate in the exertion of toxic chemical effects. The present study intended to show the toxicological effects caused by arsenic (7.2mg/kg body weight), chromium (10.2mg/kg Cr body weight) and the commercial mixture CCA (7.2mg/kg As body weight and 10.2mg/kg Cr body weight) in mice, namely the oxidative stress response (catalase - CAT, glutathione peroxidase - GPx, and glutathione-S-transferases - GSTs), in kidney tissues. The determination of the tested parameters was performed after exposure; organisms were exposed, and then sacrificed at two distinct periods, namely 14 and 96h after the administration of toxicants. Exposure to chromium and arsenic induced significant modifications in the redox state of the test organisms, evidenced by significant alterations in GSTs and GPx activities. No alterations were found concerning the activity of catalase. These findings showed that the chemical mixture used as household product may exert significant toxicological outcomes in exposed animals, such as rodents, conditioning their redox homeostasis and antioxidant response.","Mechanisms of kidney toxicity for chromium- and arsenic-based preservatives: Potential involvement of a pro-oxidative pathway Abs: Metals have been extensively used for the preservation of wood. Among metallic conservatives, mixtures of chromated copper arsenate (CCA) were thoroughly used. However, the release and consequent mobilization of such compounds by biota, may culminate in the exertion of toxic chemical effects. The present study intended to show the toxicological effects caused by arsenic (7.2mg/kg body weight), chromium (10.2mg/kg Cr body weight) and the commercial mixture CCA (7.2mg/kg As body weight and 10.2mg/kg Cr body weight) in mice, namely the oxidative stress response (catalase - CAT, glutathione peroxidase - GPx, and glutathione-S-transferases - GSTs), in kidney tissues. The determination of the tested parameters was performed after exposure; organisms were exposed, and then sacrificed at two distinct periods, namely 14 and 96h after the administration of toxicants. Exposure to chromium and arsenic induced significant modifications in the redox state of the test organisms, evidenced by significant alterations in GSTs and GPx activities. No alterations were found concerning the activity of catalase. These findings showed that the chemical mixture used as household product may exert significant toxicological outcomes in exposed animals, such as rodents, conditioning their redox homeostasis and antioxidant response."
2128577,Wilkin et al. ,Fifteen-year assessment of a permeable reactive barrier for treatment of chromate and trichloroethylene in groundwater,"The fifteen-year performance of a granular iron, permeable reactive barrier (PRB; Elizabeth City, North Carolina) is reviewed with respect to contaminant treatment (hexavalent chromium and trichloroethylene) and hydraulic performance. Due to in-situ treatment of the chromium source zone, reactive and hydraulic longevity of the PRB has outlived the mobile chromate plume. Chromium concentrations exceeding 3?g/L have not been detected in regions located hydraulically down-gradient of the PRB. Trichloroethylene treatment has also been effective, although non-constant influent concentrations of trichloroethylene have at times resulted in incomplete dechlorination. Daughter products: cis-1,2-dichloroethylene, vinyl chloride, ethene, and ethane have been observed within and down-gradient of the PRB at levels &lt;10% of the influent trichloroethylene. Analysis of potentiometric surfaces up-gradient and across the PRB suggests that the PRB may currently represent a zone of reduced hydraulic conductivity; however, measurements of the in-situ hydraulic conductivity provide values in excess of 200m/d in some intervals and indicate no discernible loss of bulk hydraulic conductivity within the PRB. The results presented here are particularly significant because they provide the longest available record of performance of a PRB. The longevity of the Elizabeth City PRB is principally the result of favorable groundwater geochemistry and hydrologic properties of the site.","Fifteen-year assessment of a permeable reactive barrier for treatment of chromate and trichloroethylene in groundwater Abs: The fifteen-year performance of a granular iron, permeable reactive barrier (PRB; Elizabeth City, North Carolina) is reviewed with respect to contaminant treatment (hexavalent chromium and trichloroethylene) and hydraulic performance. Due to in-situ treatment of the chromium source zone, reactive and hydraulic longevity of the PRB has outlived the mobile chromate plume. Chromium concentrations exceeding 3?g/L have not been detected in regions located hydraulically down-gradient of the PRB. Trichloroethylene treatment has also been effective, although non-constant influent concentrations of trichloroethylene have at times resulted in incomplete dechlorination. Daughter products: cis-1,2-dichloroethylene, vinyl chloride, ethene, and ethane have been observed within and down-gradient of the PRB at levels &lt;10% of the influent trichloroethylene. Analysis of potentiometric surfaces up-gradient and across the PRB suggests that the PRB may currently represent a zone of reduced hydraulic conductivity; however, measurements of the in-situ hydraulic conductivity provide values in excess of 200m/d in some intervals and indicate no discernible loss of bulk hydraulic conductivity within the PRB. The results presented here are particularly significant because they provide the longest available record of performance of a PRB. The longevity of the Elizabeth City PRB is principally the result of favorable groundwater geochemistry and hydrologic properties of the site."
2064168,Rehman et al. 2013,Arsenic and chromium reduction in co-cultures of bacteria isolated from industrial sites in Pakistan,,Arsenic and chromium reduction in co-cultures of bacteria isolated from industrial sites in Pakistan Abs: 
2043567,Deliyanni et al. 2013,Impregnation of activated carbon by iron oxyhydroxide and its effect on arsenate removal,,Impregnation of activated carbon by iron oxyhydroxide and its effect on arsenate removal Abs: 
2040021,Garcia et al. 2013,Emulsion liquid membrane pertraction of Cr(III) from aqueous solutions using PC-88A as carrier,,Emulsion liquid membrane pertraction of Cr(III) from aqueous solutions using PC-88A as carrier Abs: 
2037399,Hazer and  Demir 2013,Speciation of Chromium in Water Samples by Solid-Phase Extraction on a New Synthesized Adsorbent,,Speciation of Chromium in Water Samples by Solid-Phase Extraction on a New Synthesized Adsorbent Abs: 
2033604,Katal et al. 2013,Synthesis of Fe3O4/polyaniline nanocomposite and its application for nitrate removal from aqueous solutions,"The aim of this work was to investigate the sorption characteristics of Fe3O4 coated on polyaniline (Fe3O4/PAn) for the removal of NO3 ions from aqueous solutions. The sorption of NO3 ions by the batch method was carried out. The optimum conditions of sorption were found to be a Fe3O4/PAn dose of 0.4 g in 100 mL of NO3 solution, a contact time of 10 min, pH and temperature 7 and 40 degrees C, respectively. Temperature had a negative effect on the removal efficiency. Three equations, i.e., MorrisWeber, Lagergren, and pseudo-second-order, were tested to track the kinetics of the removal process. The Langmuir, Freundlich, and DubininRadushkevich isotherm models were subjected to sorption data in order to estimate sorption capacity, intensity, and energy. The thermodynamic parameters H, S, and G were evaluated. They showed that the adsorption of NO3 onto Fe3O4/PAn was feasible, spontaneous, and exothermic under the studied conditions. It can be concluded that Fe3O4/PAn has potential to remove NO3 ions from aqueous solutions at different concentrations. The system Fe3O4/Pan was successfully tested for a high removal efficiency of NO3 from urban wastewater. J. VINYL ADDIT. TECHNOL., 19:147156, 2013. (c) 2013 Society of Plastics Engineers","Synthesis of Fe3O4/polyaniline nanocomposite and its application for nitrate removal from aqueous solutions Abs: The aim of this work was to investigate the sorption characteristics of Fe3O4 coated on polyaniline (Fe3O4/PAn) for the removal of NO3 ions from aqueous solutions. The sorption of NO3 ions by the batch method was carried out. The optimum conditions of sorption were found to be a Fe3O4/PAn dose of 0.4 g in 100 mL of NO3 solution, a contact time of 10 min, pH and temperature 7 and 40 degrees C, respectively. Temperature had a negative effect on the removal efficiency. Three equations, i.e., MorrisWeber, Lagergren, and pseudo-second-order, were tested to track the kinetics of the removal process. The Langmuir, Freundlich, and DubininRadushkevich isotherm models were subjected to sorption data in order to estimate sorption capacity, intensity, and energy. The thermodynamic parameters H, S, and G were evaluated. They showed that the adsorption of NO3 onto Fe3O4/PAn was feasible, spontaneous, and exothermic under the studied conditions. It can be concluded that Fe3O4/PAn has potential to remove NO3 ions from aqueous solutions at different concentrations. The system Fe3O4/Pan was successfully tested for a high removal efficiency of NO3 from urban wastewater. J. VINYL ADDIT. TECHNOL., 19:147156, 2013. (c) 2013 Society of Plastics Engineers"
2032016,Kowalczyk et al. 2013,Modern hybrid sorbents - New ways of heavy metal removal from waters,"The possibility of hybrid ion exchanger (HIX) application in the simultaneous removal of heavy metal ions such as Cr(VI), Cu(II) and Zn(II) as well as Cd(II) and Pb(II) was presented. The ion exchanger in question combines the unique properties of hydrated metal oxides with the mechanical and thermal stability of synthetic ion exchangers. The kinetics of the sorption process of Cr(VI), Cu(II) and Zn(II) as well as Cd(II) and Pb(II) in the presence of Cl-, NO3- and SO42- as well as EDDS (ethylenediaminedisuccinic acid) was also analyzed. Additionally, the effect of initial concentration, phase contact time and pH was also studied. Taking into account the possibility of its application on a large scale, the parameters of the adsorption process were estimated based on the linear form of the Langmuir and Freundlich isotherms. (C) 2013 Elsevier B.V. All rights reserved.","Modern hybrid sorbents - New ways of heavy metal removal from waters Abs: The possibility of hybrid ion exchanger (HIX) application in the simultaneous removal of heavy metal ions such as Cr(VI), Cu(II) and Zn(II) as well as Cd(II) and Pb(II) was presented. The ion exchanger in question combines the unique properties of hydrated metal oxides with the mechanical and thermal stability of synthetic ion exchangers. The kinetics of the sorption process of Cr(VI), Cu(II) and Zn(II) as well as Cd(II) and Pb(II) in the presence of Cl-, NO3- and SO42- as well as EDDS (ethylenediaminedisuccinic acid) was also analyzed. Additionally, the effect of initial concentration, phase contact time and pH was also studied. Taking into account the possibility of its application on a large scale, the parameters of the adsorption process were estimated based on the linear form of the Langmuir and Freundlich isotherms. (C) 2013 Elsevier B.V. All rights reserved."
2016006,Singh et al. 2013,Chromium toxicity and tolerance in plants,,Chromium toxicity and tolerance in plants Abs: 
2013430,Teng et al. 2013,"Removal of Hexavalent Chromium from Aqueous Solutions by Sodium Dodecyl Sulfate Stabilized Nano Zero-Valent Iron: A Kinetics, Equilibrium, Thermodynamics Study",,"Removal of Hexavalent Chromium from Aqueous Solutions by Sodium Dodecyl Sulfate Stabilized Nano Zero-Valent Iron: A Kinetics, Equilibrium, Thermodynamics Study Abs: "
2012301,Uygun et al. 2013,New generation ion-imprinted nanocarrier for removal of Cr(VI) from wastewater,,New generation ion-imprinted nanocarrier for removal of Cr(VI) from wastewater Abs: 
2010743,Wang et al. 2013,Highly efficient adsorption of Cr(VI) from aqueous solutions by amino-functionalized titanate nanotubes,"For highly efficient removal of Cr(VI) from aqueous solutions, amino-functionalized titanate nanotubes (NH2-TNTs) with excellent adsorption performance have been synthesized by covalently grafting [1-(2-amino-ethyl)-3-aminopropyl]trimethoxysilane (AAPTS) onto protonated titanate nanotubes (HTNTs) with great amounts of surface hydroxyl groups. TEM and XRD results confirmed that the nanotubular morphology and crystal structure of HTNTs and NH2-TNTs were preserved. FTIR spectra demonstrated that AAPTS was covalently bonded on the surface of HTNTs. Batch adsorption experiments showed that pseudo-second-order kinetics model and Langmuir isotherm model fitted the adsorption data very well for both materials, and the Cr(VI) adsorption capacity on NH2-TNTs calculated by Langmuir model was up to 153.85 mg g(-1) at initial pH 5.4 and 30 degrees C, much larger than that on HTNTs (26.60 mg g(-1)). Moreover, uptake of Cr(VI) ions onto NH2-TNTs could be completed within only 5 min for 95% adsorption of the maximum. Influence of different species of Cr(VI) under varying pH was also considered. FTIR and XPS analysis indicated that Cr(VI) ions were first exchanged with NO3- linked on the positively charged amino groups and then partially reduced to Cr(III). Afterwards, Cr(III) were then totally chelated with amino groups and no Cr(III) was detected in the solution after Cr(VI) adsorption at pH range of 1-12. (C) 2013 Elsevier B.V. All rights reserved.","Highly efficient adsorption of Cr(VI) from aqueous solutions by amino-functionalized titanate nanotubes Abs: For highly efficient removal of Cr(VI) from aqueous solutions, amino-functionalized titanate nanotubes (NH2-TNTs) with excellent adsorption performance have been synthesized by covalently grafting [1-(2-amino-ethyl)-3-aminopropyl]trimethoxysilane (AAPTS) onto protonated titanate nanotubes (HTNTs) with great amounts of surface hydroxyl groups. TEM and XRD results confirmed that the nanotubular morphology and crystal structure of HTNTs and NH2-TNTs were preserved. FTIR spectra demonstrated that AAPTS was covalently bonded on the surface of HTNTs. Batch adsorption experiments showed that pseudo-second-order kinetics model and Langmuir isotherm model fitted the adsorption data very well for both materials, and the Cr(VI) adsorption capacity on NH2-TNTs calculated by Langmuir model was up to 153.85 mg g(-1) at initial pH 5.4 and 30 degrees C, much larger than that on HTNTs (26.60 mg g(-1)). Moreover, uptake of Cr(VI) ions onto NH2-TNTs could be completed within only 5 min for 95% adsorption of the maximum. Influence of different species of Cr(VI) under varying pH was also considered. FTIR and XPS analysis indicated that Cr(VI) ions were first exchanged with NO3- linked on the positively charged amino groups and then partially reduced to Cr(III). Afterwards, Cr(III) were then totally chelated with amino groups and no Cr(III) was detected in the solution after Cr(VI) adsorption at pH range of 1-12. (C) 2013 Elsevier B.V. All rights reserved."
2010063,Weber et al. 2013,Investigating dominant processes in ZVI permeable reactive barriers using reactive transport modeling,,Investigating dominant processes in ZVI permeable reactive barriers using reactive transport modeling Abs: 
2007403,Yousefi and  Shemirani 2013,Selective and sensitive speciation analysis of Cr(VI) and Cr(III) in water samples by fiber optic-linear array detection spectrophotometry after ion pair based-surfactant assisted dispersive liquid-liquid microextraction,"A simple ion pair based-surfactant assisted dispersive liquid-liquid microextraction (IP-SA-DLLME) was evaluated for extraction and preconcentration of Cr(VI) and Cr(III) in aqueous samples. In this method, which was used for the first time for chromium speciation analysis, sodium dodecyl sulfate (SDS) was used as both ion-pairing and disperser agent. Cr(VI) ions were converted into their cationic complex with 1,5-diphenylcarbazide (DPC) and then extracted into 1-octanol dispersed in aqueous solution. Cr(III) ion also can be determined by this procedure after oxidation to Cr(VI). After extraction and phase separation, upper organic phase was transferred to a micro cell of a fiber optic-linear array detection spectrophotometry (FO-LADS). The effects of various parameters on the extraction recovery were investigated. Under the optimized conditions and preconcentration of 10 mL of sample, the enrichment factor of 159 and the detection limit of 0.05 ?gL(-1) were obtained. Validation of the method was performed by spiking-recovery method and comparison of results with those obtained by ET-AAS method.","Selective and sensitive speciation analysis of Cr(VI) and Cr(III) in water samples by fiber optic-linear array detection spectrophotometry after ion pair based-surfactant assisted dispersive liquid-liquid microextraction Abs: A simple ion pair based-surfactant assisted dispersive liquid-liquid microextraction (IP-SA-DLLME) was evaluated for extraction and preconcentration of Cr(VI) and Cr(III) in aqueous samples. In this method, which was used for the first time for chromium speciation analysis, sodium dodecyl sulfate (SDS) was used as both ion-pairing and disperser agent. Cr(VI) ions were converted into their cationic complex with 1,5-diphenylcarbazide (DPC) and then extracted into 1-octanol dispersed in aqueous solution. Cr(III) ion also can be determined by this procedure after oxidation to Cr(VI). After extraction and phase separation, upper organic phase was transferred to a micro cell of a fiber optic-linear array detection spectrophotometry (FO-LADS). The effects of various parameters on the extraction recovery were investigated. Under the optimized conditions and preconcentration of 10 mL of sample, the enrichment factor of 159 and the detection limit of 0.05 ?gL(-1) were obtained. Validation of the method was performed by spiking-recovery method and comparison of results with those obtained by ET-AAS method."
2003559,Zhu et al. 2013,The nature of Schwertmannite and Jarosite mediated by two strains of Acidithiobacillus ferrooxidans with different ferrous oxidation ability,,The nature of Schwertmannite and Jarosite mediated by two strains of Acidithiobacillus ferrooxidans with different ferrous oxidation ability Abs: 
2000747,Badruddoza et al. 2013,Ionically modified magnetic nanomaterials for arsenic and chromium removal from water,,Ionically modified magnetic nanomaterials for arsenic and chromium removal from water Abs: 
1812703,Zou et al. ,Supercritical water oxidation of tannery sludge: Stabilization of chromium and destruction of organics,"The supercritical water oxidation (SCWO) of industrial tannery sludge was investigated to understand the simultaneous destruction of organic pollutants and recovery of high content chromium. Experiments were performed in a batch reactor at temperatures of 350-500°C, reaction time of 150-300s and different oxygen ratios, to exhibit the effect of operation conditions. Results showed that removal efficiency of chemical oxygen demand (COD) increased with higher temperature, larger oxidant amount and reaction time; a maximum value of 96% was obtained. Meanwhile, destruction yield was much higher under supercritical conditions than that in subcritical water. In addition, removal efficiency of Cr from sludge reached more than 98% under all conditions; higher temperature played a positive role. Further, leaching toxicity tests of heavy metals in solid products were conducted based on toxicity characteristic leaching procedure. All heavy metals except nickel showed a greatly reduced leaching toxicity through their stabilization. The chromium oxide recovered in ash was amorphous below 550°C, so that the structure of Cr could not be identified by X-ray diffraction pattern. Special attention should be paid on nickel as its leaching toxicity increased due to the corrosion of reactor surface under severe reaction conditions.","Supercritical water oxidation of tannery sludge: Stabilization of chromium and destruction of organics Abs: The supercritical water oxidation (SCWO) of industrial tannery sludge was investigated to understand the simultaneous destruction of organic pollutants and recovery of high content chromium. Experiments were performed in a batch reactor at temperatures of 350-500°C, reaction time of 150-300s and different oxygen ratios, to exhibit the effect of operation conditions. Results showed that removal efficiency of chemical oxygen demand (COD) increased with higher temperature, larger oxidant amount and reaction time; a maximum value of 96% was obtained. Meanwhile, destruction yield was much higher under supercritical conditions than that in subcritical water. In addition, removal efficiency of Cr from sludge reached more than 98% under all conditions; higher temperature played a positive role. Further, leaching toxicity tests of heavy metals in solid products were conducted based on toxicity characteristic leaching procedure. All heavy metals except nickel showed a greatly reduced leaching toxicity through their stabilization. The chromium oxide recovered in ash was amorphous below 550°C, so that the structure of Cr could not be identified by X-ray diffraction pattern. Special attention should be paid on nickel as its leaching toxicity increased due to the corrosion of reactor surface under severe reaction conditions."
1807699,Yu et al. ,Adsorption of Cr(VI) using synthetic poly(m-phenylenediamine),"Poly(m-phenylenediamine) (PmPD) with different oxidation state was successfully synthesized by the improved chemically oxidative polymerization. The function of oxidation state on Cr(VI) adsorption was systematically examined through adsorption experiments. Results showed that the Cr(VI) adsorptivity of all PmPD increased with decreasing the initial pH. When the oxidation state of PmPD was dropped, the equilibrium time for Cr(VI) adsorption was obviously shortened and its Cr(VI) removal and adsorption selectivity were profoundly obviously increased. Typically, PmPD with the lowest oxidation state in this research possesses the highest Cr(VI) removal of 500mgg(-1). Moreover, PmPD with lower oxidation state displays a potentially superior prospect in Cr(VI) treatment through preliminary experiments on 5 cycles of adsorption, column adsorption and practical wastewater treatment. The possible adsorption mechanism was discussed mainly according to characterizations (FTIR, XPS) and experiments, which together suggests that the Cr(VI) adsorption most possibly involve redox reaction, chelation and doping adsorption.","Adsorption of Cr(VI) using synthetic poly(m-phenylenediamine) Abs: Poly(m-phenylenediamine) (PmPD) with different oxidation state was successfully synthesized by the improved chemically oxidative polymerization. The function of oxidation state on Cr(VI) adsorption was systematically examined through adsorption experiments. Results showed that the Cr(VI) adsorptivity of all PmPD increased with decreasing the initial pH. When the oxidation state of PmPD was dropped, the equilibrium time for Cr(VI) adsorption was obviously shortened and its Cr(VI) removal and adsorption selectivity were profoundly obviously increased. Typically, PmPD with the lowest oxidation state in this research possesses the highest Cr(VI) removal of 500mgg(-1). Moreover, PmPD with lower oxidation state displays a potentially superior prospect in Cr(VI) treatment through preliminary experiments on 5 cycles of adsorption, column adsorption and practical wastewater treatment. The possible adsorption mechanism was discussed mainly according to characterizations (FTIR, XPS) and experiments, which together suggests that the Cr(VI) adsorption most possibly involve redox reaction, chelation and doping adsorption."
1792806,Starek 1991,Barrier creams in the prevention of occupational contact dermatitis--an experimental study,"Experimental evaluation of two barrier creams has been carried out. One of these creams was composed of hydrocarbon components; the other had, in addition, silicone oil and cetaceum. The protective properties of these creams on rats and guinea pigs have been examined. It was found that investigated creams exerted an inhibiting effect on the absorption of chromium and nickel through the skin of rats from aqueous solutions. Moreover, the creams demonstrated a pronounced protective action on guinea pigs sensitized to chromium.","Barrier creams in the prevention of occupational contact dermatitis--an experimental study Abs: Experimental evaluation of two barrier creams has been carried out. One of these creams was composed of hydrocarbon components; the other had, in addition, silicone oil and cetaceum. The protective properties of these creams on rats and guinea pigs have been examined. It was found that investigated creams exerted an inhibiting effect on the absorption of chromium and nickel through the skin of rats from aqueous solutions. Moreover, the creams demonstrated a pronounced protective action on guinea pigs sensitized to chromium."
1790952,Kirman et al. 2013,Physiologically based pharmacokinetic model for humans orally exposed to chromium,"A multi-compartment physiologically based pharmacokinetic (PBPK) model was developed to describe the behavior of Cr(III) and Cr(VI) in humans. Compartments were included for gastrointestinal lumen, oral mucosa, stomach, small intestinal tissue, blood, liver, kidney, bone, and a combined compartment for remaining tissues. As chronic exposure to high concentrations of Cr(VI) in drinking water cause small intestinal cancer in mice, the toxicokinetics of Cr(VI) in the upper gastrointestinal tract of rodents and humans are important for assessing internal tissue dose in risk assessment. Fasted human stomach fluid was collected and ex vivo Cr(VI) reduction studies were conducted and used to characterize reduction of Cr(VI) in human stomach fluid as a mixed second-order, pH-dependent process. For model development, toxicokinetic data for total chromium in human tissues and excreta were identified from the published literature. Overall, the PBPK model provides a good description of chromium toxicokinetics and is consistent with the available total chromium data from Cr(III) and Cr(VI) exposures in typical humans (i.e., model predictions are within a factor of three for approximately 86% of available data). By accounting for key species differences, sources of saturable toxicokinetics, and sources of uncertainty and variation, the rodent and human PBPK models can provide a robust characterization of toxicokinetics in the target tissue of the small intestine allowing for improved health risk assessment of human populations exposed to environmentally-relevant concentrations.","Physiologically based pharmacokinetic model for humans orally exposed to chromium Abs: A multi-compartment physiologically based pharmacokinetic (PBPK) model was developed to describe the behavior of Cr(III) and Cr(VI) in humans. Compartments were included for gastrointestinal lumen, oral mucosa, stomach, small intestinal tissue, blood, liver, kidney, bone, and a combined compartment for remaining tissues. As chronic exposure to high concentrations of Cr(VI) in drinking water cause small intestinal cancer in mice, the toxicokinetics of Cr(VI) in the upper gastrointestinal tract of rodents and humans are important for assessing internal tissue dose in risk assessment. Fasted human stomach fluid was collected and ex vivo Cr(VI) reduction studies were conducted and used to characterize reduction of Cr(VI) in human stomach fluid as a mixed second-order, pH-dependent process. For model development, toxicokinetic data for total chromium in human tissues and excreta were identified from the published literature. Overall, the PBPK model provides a good description of chromium toxicokinetics and is consistent with the available total chromium data from Cr(III) and Cr(VI) exposures in typical humans (i.e., model predictions are within a factor of three for approximately 86% of available data). By accounting for key species differences, sources of saturable toxicokinetics, and sources of uncertainty and variation, the rodent and human PBPK models can provide a robust characterization of toxicokinetics in the target tissue of the small intestine allowing for improved health risk assessment of human populations exposed to environmentally-relevant concentrations."
1788795,Kaushal and  Nema ,Multi-stakeholder decision analysis and comparative risk assessment for reuse- recycle oriented e-waste management strategies: a game theoretic approach,"This article deals with assessment of the potential health risk posed by carcinogenic and non-carcinogenic substances, namely lead (Pb), cadmium (Cd), copper, chromium (CrVI), zinc, nickel and mercury, present in e-waste. A multi-objective, multi-stakeholder approach based on strategic game theory model has been developed considering cost, as well as human health risk. The trade-off due to cost difference between a hazardous substances-free (HSF) and a hazardous substance (HS)-containing desktop computer, and the risk posed by them at the time of disposal, has been analyzed. The cancer risk due to dust inhalation for workers at a recycling site in Bangalore for Pb, Cr(VI) and Cd was found to be 4, 33 and 101 in 1 million respectively. Pb and Cr(VI) result in a very high risk owing to dust ingestion at slums near the recycling site-175 and 81 in 1 million for children, and 24 and 11 in 1 million for adults respectively. The concentration of Pb at a battery workshop in Mayapuri, Delhi (hazard quotient = 3.178) was found to pose adverse health hazards. The government may impose an appropriate penalty on the land disposal of computer waste and/or may give an incentive to manufacturer for producing HSF computers through, for example, relaxing taxes, but there should be no such incentive for manufacturing HS-containing computers.","Multi-stakeholder decision analysis and comparative risk assessment for reuse- recycle oriented e-waste management strategies: a game theoretic approach Abs: This article deals with assessment of the potential health risk posed by carcinogenic and non-carcinogenic substances, namely lead (Pb), cadmium (Cd), copper, chromium (CrVI), zinc, nickel and mercury, present in e-waste. A multi-objective, multi-stakeholder approach based on strategic game theory model has been developed considering cost, as well as human health risk. The trade-off due to cost difference between a hazardous substances-free (HSF) and a hazardous substance (HS)-containing desktop computer, and the risk posed by them at the time of disposal, has been analyzed. The cancer risk due to dust inhalation for workers at a recycling site in Bangalore for Pb, Cr(VI) and Cd was found to be 4, 33 and 101 in 1 million respectively. Pb and Cr(VI) result in a very high risk owing to dust ingestion at slums near the recycling site-175 and 81 in 1 million for children, and 24 and 11 in 1 million for adults respectively. The concentration of Pb at a battery workshop in Mayapuri, Delhi (hazard quotient = 3.178) was found to pose adverse health hazards. The government may impose an appropriate penalty on the land disposal of computer waste and/or may give an incentive to manufacturer for producing HSF computers through, for example, relaxing taxes, but there should be no such incentive for manufacturing HS-containing computers."
1786501,Zhu et al. 2013,"Study on Adsorption Characteristics of Cr(VI) on Poly(N,N '-dimethylamino ethyl methacrylate) Hydrogels","Poly(N,N'-dimethylamino ethyl methacrylate) [poly(DMAEMA)] hydrogel was synthesized and the adsorption characteristics of Cr(VI) ions on it were evaluated. A series of static adsorption experiments with Cr(VI) were carried out at different mass of cross-linker, temperature, pH and concentration of Cr(VI). It was found that the optimum pH was 2 and the maximum adsorption amount of Cr(VI) were up to 116 mg/g. The results of the adsorption kinetics and isotherms indicated the adsorption date were well fitted with the preudo-second order model and Langmuir model, respectively. The desorption experiments showed that more than 97.4 % Cr(VI) can be desorbed by NaOH (pH = 10). The present study proved that the poly(DMAEMA) gel was an excellent potential Cr(VI) adsorbent.","Study on Adsorption Characteristics of Cr(VI) on Poly(N,N '-dimethylamino ethyl methacrylate) Hydrogels Abs: Poly(N,N'-dimethylamino ethyl methacrylate) [poly(DMAEMA)] hydrogel was synthesized and the adsorption characteristics of Cr(VI) ions on it were evaluated. A series of static adsorption experiments with Cr(VI) were carried out at different mass of cross-linker, temperature, pH and concentration of Cr(VI). It was found that the optimum pH was 2 and the maximum adsorption amount of Cr(VI) were up to 116 mg/g. The results of the adsorption kinetics and isotherms indicated the adsorption date were well fitted with the preudo-second order model and Langmuir model, respectively. The desorption experiments showed that more than 97.4 % Cr(VI) can be desorbed by NaOH (pH = 10). The present study proved that the poly(DMAEMA) gel was an excellent potential Cr(VI) adsorbent."
1786500,Zhang and  Sun 2013,Preparation of Nano-Strontium Titanate Based on Glass Fiber Filter and Its Application in Speciation Analysis for Chromium,"Nano-strontium titanate based on glass fiber filter was successfully prepared by sol-gel method and characterized using XRD and SEM. Its application in speciation of Cr(III) and Cr(VI) from water was studied. Adsorption and elution were investigated under different conditions. The results showed that the nano-strontium titanate could crystal based on glass fiber, gaining a new block adsorbent like a leaf. At normal temperature, the adsorbent had strong adsorption capacity for Cr(II) and Cr(VI) in wate rbut two forms of chromium show different adsorption capacities at different pH values, that is, Cr(III) selectively retained at pH 7-14, but Cr(VI) can be adsorbed. Whereas Cr(VI) retained at pH 1-3, but Cr(III) can't be adsorbed. Hence complete separation of the two forms of chromium is possible. Retained Cr(III) and Cr(VI) were eluted with 1 mol/L HCl and 2 mol/L NaOH, respectively. Based on these, a simple and sensitive method for the speciation, seperation and preconventration of Cr(VI) and Cr(III) in environmental water was developed. The method was applied for the speciation of chromium in environmental water samples and measured by atomic absorption spectroscopy.","Preparation of Nano-Strontium Titanate Based on Glass Fiber Filter and Its Application in Speciation Analysis for Chromium Abs: Nano-strontium titanate based on glass fiber filter was successfully prepared by sol-gel method and characterized using XRD and SEM. Its application in speciation of Cr(III) and Cr(VI) from water was studied. Adsorption and elution were investigated under different conditions. The results showed that the nano-strontium titanate could crystal based on glass fiber, gaining a new block adsorbent like a leaf. At normal temperature, the adsorbent had strong adsorption capacity for Cr(II) and Cr(VI) in wate rbut two forms of chromium show different adsorption capacities at different pH values, that is, Cr(III) selectively retained at pH 7-14, but Cr(VI) can be adsorbed. Whereas Cr(VI) retained at pH 1-3, but Cr(III) can't be adsorbed. Hence complete separation of the two forms of chromium is possible. Retained Cr(III) and Cr(VI) were eluted with 1 mol/L HCl and 2 mol/L NaOH, respectively. Based on these, a simple and sensitive method for the speciation, seperation and preconventration of Cr(VI) and Cr(III) in environmental water was developed. The method was applied for the speciation of chromium in environmental water samples and measured by atomic absorption spectroscopy."
1786499,Zhang 2013,Simultaneous Determination of Chromium(VI) and Manganese(VII) by Differential Kinetic Rate Spectrophotometry of Direct Yellow Brown D3G,"In this study, the fading reaction of Cr(VI) and Mn(VII) oxidating direct yellow brown D3G, a textile dyes, was investigated. In sulfuric acid medium, at 90 in water bath, both Cr(VI) and Mn(VII) could fade direct yellow brown D3G, but the fading rate was different. Moreover, there was no obvious synergistic effect between them. A new method to determine Cr(VI) and Mn(VII) by differential reaction rate kinetic direct yellow brown D3G fading spectrophotometry was purposed. The effect of medium acidity, the dosage of direct yellow brown D3G, reaction temperature and time on fading reaction was studied and the proportion equation was established. This method could be used to determine Cr(VI) and Mn(VI.) in industrial wastewater and the results were according to the flame atomic absorption spectrophotometry.","Simultaneous Determination of Chromium(VI) and Manganese(VII) by Differential Kinetic Rate Spectrophotometry of Direct Yellow Brown D3G Abs: In this study, the fading reaction of Cr(VI) and Mn(VII) oxidating direct yellow brown D3G, a textile dyes, was investigated. In sulfuric acid medium, at 90 in water bath, both Cr(VI) and Mn(VII) could fade direct yellow brown D3G, but the fading rate was different. Moreover, there was no obvious synergistic effect between them. A new method to determine Cr(VI) and Mn(VII) by differential reaction rate kinetic direct yellow brown D3G fading spectrophotometry was purposed. The effect of medium acidity, the dosage of direct yellow brown D3G, reaction temperature and time on fading reaction was studied and the proportion equation was established. This method could be used to determine Cr(VI) and Mn(VI.) in industrial wastewater and the results were according to the flame atomic absorption spectrophotometry."
1786498,Wyszkowski and  Radziemska 2013,INFLUENCE OF CHROMIUM (III) AND (VI) ON THE CONCENTRATION OF MINERAL ELEMENTS IN OAT (Avena sativa L.),"The research aimed to determine the influence of Cr (III) and Cr (VI) in doses of 0, 25, 50, 100 and 150 mg Cr.kg(-1) of soil as well as compost, zeolite and CaO additives on the content of mineral substances in the grain, straw and roots of oat (Avena sativa L.). The content of phosphorus, potassium, sodium, calcium and magnesium in oat depended on the dose of chromium, type of neutralizing substances, and analyzed plant part. The highest doses of Cr (III) and Cr (VI) decreased the content of the analyzed nutrients in the majority of the plant parts. Conversely to potassium, the addition of compost, zeolite, and CaO to soil containing Cr (VI), and especially Cr (III), caused a significant increase in calcium, phosphorus, and magnesium content in oat grain.","INFLUENCE OF CHROMIUM (III) AND (VI) ON THE CONCENTRATION OF MINERAL ELEMENTS IN OAT (Avena sativa L.) Abs: The research aimed to determine the influence of Cr (III) and Cr (VI) in doses of 0, 25, 50, 100 and 150 mg Cr.kg(-1) of soil as well as compost, zeolite and CaO additives on the content of mineral substances in the grain, straw and roots of oat (Avena sativa L.). The content of phosphorus, potassium, sodium, calcium and magnesium in oat depended on the dose of chromium, type of neutralizing substances, and analyzed plant part. The highest doses of Cr (III) and Cr (VI) decreased the content of the analyzed nutrients in the majority of the plant parts. Conversely to potassium, the addition of compost, zeolite, and CaO to soil containing Cr (VI), and especially Cr (III), caused a significant increase in calcium, phosphorus, and magnesium content in oat grain."
1786497,Wang et al. 2013,Determination of Trace Migratory Chromium(VI) in Toys by High Performance Liquid Chromatography-Inductively Coupled Plasma Mass Spectrometry,"A method for determinating trace migratory chromium(VI) in toys by hyphenated technique of high performance liquid chromatography-inductively coupled plasma mass spectrometry (HPLC-ICP-MS) has been developed in this article. The chromium species Cr(III) and Cr(VI) were separated on an Dionex AS19 analysis column using ammonium nitrate as the mobile phase with pH 7.4 at flow rate 1.0 mL/min. And the chromatographic separation was increased as the concentration of mobile phase was decreased. This method was easy to operate and with remarkably high sensitivity. The detection limit was found to be 0.02 mu g/L of Cr(VI) for 100 mu L injection volume in He collision cell mode of mass spectrometry. The spiked recoveries were at the range of 98.8%-104.2% and 96.3%-100.4% for the spiked levels of 0.50 mu g/L and 5.00 mu g/L respectively, and the RSDs were less than 4.2%, which met the determination requirements. This method has been used to determine migratory Cr(VI) in accessible parts of toys, including coating, plastic, wood and textile. The results were satisfactory.","Determination of Trace Migratory Chromium(VI) in Toys by High Performance Liquid Chromatography-Inductively Coupled Plasma Mass Spectrometry Abs: A method for determinating trace migratory chromium(VI) in toys by hyphenated technique of high performance liquid chromatography-inductively coupled plasma mass spectrometry (HPLC-ICP-MS) has been developed in this article. The chromium species Cr(III) and Cr(VI) were separated on an Dionex AS19 analysis column using ammonium nitrate as the mobile phase with pH 7.4 at flow rate 1.0 mL/min. And the chromatographic separation was increased as the concentration of mobile phase was decreased. This method was easy to operate and with remarkably high sensitivity. The detection limit was found to be 0.02 mu g/L of Cr(VI) for 100 mu L injection volume in He collision cell mode of mass spectrometry. The spiked recoveries were at the range of 98.8%-104.2% and 96.3%-100.4% for the spiked levels of 0.50 mu g/L and 5.00 mu g/L respectively, and the RSDs were less than 4.2%, which met the determination requirements. This method has been used to determine migratory Cr(VI) in accessible parts of toys, including coating, plastic, wood and textile. The results were satisfactory."
1786496,Wang et al. 2013,Polyacrylonitrile/polyaniline core/shell nanofiber mat for removal of hexavalent chromium from aqueous solution: mechanism and applications,"Polyacrylonitrile/polyaniline core/shell nanofibers were prepared via electrospinning followed by in situ polymerization of aniline. Nanofibers with different morphology were obtained by changing the polymerization temperature. When used as absorbent for Cr(VI) ions, the core/shell nanofiber mats exhibit excellent adsorption capability. The equilibrium capacity is 24.96, 37.24, and 52.00 mg g(-1) for 105, 156, and 207 mg L-1 initial Cr(VI) solution, respectively, and the adsorption capacity increases with temperature. The adsorption follows a pseudo second order kinetics model and is best fit using the Langmuir isotherm model. The mats show excellent selectivity towards Cr(VI) ions in the presence of competing ions albeit a small decrease in adsorption is observed. The mats can be regenerated and reused after treatment with NaOH making them promising candidates as practical adsorbents for Cr(VI) removal.","Polyacrylonitrile/polyaniline core/shell nanofiber mat for removal of hexavalent chromium from aqueous solution: mechanism and applications Abs: Polyacrylonitrile/polyaniline core/shell nanofibers were prepared via electrospinning followed by in situ polymerization of aniline. Nanofibers with different morphology were obtained by changing the polymerization temperature. When used as absorbent for Cr(VI) ions, the core/shell nanofiber mats exhibit excellent adsorption capability. The equilibrium capacity is 24.96, 37.24, and 52.00 mg g(-1) for 105, 156, and 207 mg L-1 initial Cr(VI) solution, respectively, and the adsorption capacity increases with temperature. The adsorption follows a pseudo second order kinetics model and is best fit using the Langmuir isotherm model. The mats show excellent selectivity towards Cr(VI) ions in the presence of competing ions albeit a small decrease in adsorption is observed. The mats can be regenerated and reused after treatment with NaOH making them promising candidates as practical adsorbents for Cr(VI) removal."
1786495,Villanueva Diaz et al. 2013,REUSE OF CITRULLUS LANATUS PEEL AS BIOSORBENT TO REMOVE ALUMINUM IN AQUEOUS PHASE,"This work presents experimental results for the removal of aluminium from aqueous solutions. Aluminium adsorption from solutions in the range of pH 2 to 3.5 on Citrullus lanatus was compared to biomasses that were conditioned with boiling or acidic pretreatments. The adsorption isotherms and the effects of different variables such as the treatment of the biomass, pH, metal concentration and reaction time on the aluminium removal efficiency were determined. Up to 90% removal of Al (III) was achieved. The adsorbent materials were characterised with scanning electron microscopy, energy dispersive X-ray spectroscopy and infrared spectroscopy before and after they came in contact with the aqueous aluminium solutions. Finally, the capacity of the Citrullus lanatus for adsorption of aluminium was described adequately by the Freundlich isotherm adsorption.","REUSE OF CITRULLUS LANATUS PEEL AS BIOSORBENT TO REMOVE ALUMINUM IN AQUEOUS PHASE Abs: This work presents experimental results for the removal of aluminium from aqueous solutions. Aluminium adsorption from solutions in the range of pH 2 to 3.5 on Citrullus lanatus was compared to biomasses that were conditioned with boiling or acidic pretreatments. The adsorption isotherms and the effects of different variables such as the treatment of the biomass, pH, metal concentration and reaction time on the aluminium removal efficiency were determined. Up to 90% removal of Al (III) was achieved. The adsorbent materials were characterised with scanning electron microscopy, energy dispersive X-ray spectroscopy and infrared spectroscopy before and after they came in contact with the aqueous aluminium solutions. Finally, the capacity of the Citrullus lanatus for adsorption of aluminium was described adequately by the Freundlich isotherm adsorption."
1786494,Tatsumi et al. 2013,Determination of Chromium (VI) by Two-channel Flow Injection Analysis System Using Dilute Acetone-based Diphenylcarbazide Solution,"Many spectrophotometric methods by flow-injection analysis (FIA) have been reported, which are based on the reaction of chromium (VI) with diphenylcarbazide. In those methods, organic solvents, such as acetone, ethanol, 1-propanol, are used to dissolve diphenylcarbazide, so that the reagent solution contained organic solvent in high or less concentration. However, it is preferable to reduce the amount of organic solvent flowing into the system, especially in cases using a peristaltic pump. In this study, FIA with the reagent solution containing acetone less than the conventional methods was examined using a compact manifold, which consists of an all-in-one peristaltic pump, injector, thermostat and photometric detector. The absorbance was measured at 540 nm. The reagent conditions and the FIA parameters were examined for optimization; the reagent solution (H2SO4 0.36 mol L-1-diphenylcarbazide 0:5 g L-1-5 v/v% acetone) and carrier (water) were both flowed at a flow rate of 0.425 mL min(-1), the reactor was maintained at 40 degrees C, and a 200 mu L, sample was injected. Under these conditions, the calibration curve was linear from 0.005 to 5 mg L-1 (R-2: 0.9998) of chromium(VI) and the relative standard deviation was 3 % (n = 5) at the 0.005 mg L-1 level. Good results were obtained in recovery tests using sample solutions from soil leaching and content tests according to the Japanese environmental quality standards for soil pollution.","Determination of Chromium (VI) by Two-channel Flow Injection Analysis System Using Dilute Acetone-based Diphenylcarbazide Solution Abs: Many spectrophotometric methods by flow-injection analysis (FIA) have been reported, which are based on the reaction of chromium (VI) with diphenylcarbazide. In those methods, organic solvents, such as acetone, ethanol, 1-propanol, are used to dissolve diphenylcarbazide, so that the reagent solution contained organic solvent in high or less concentration. However, it is preferable to reduce the amount of organic solvent flowing into the system, especially in cases using a peristaltic pump. In this study, FIA with the reagent solution containing acetone less than the conventional methods was examined using a compact manifold, which consists of an all-in-one peristaltic pump, injector, thermostat and photometric detector. The absorbance was measured at 540 nm. The reagent conditions and the FIA parameters were examined for optimization; the reagent solution (H2SO4 0.36 mol L-1-diphenylcarbazide 0:5 g L-1-5 v/v% acetone) and carrier (water) were both flowed at a flow rate of 0.425 mL min(-1), the reactor was maintained at 40 degrees C, and a 200 mu L, sample was injected. Under these conditions, the calibration curve was linear from 0.005 to 5 mg L-1 (R-2: 0.9998) of chromium(VI) and the relative standard deviation was 3 % (n = 5) at the 0.005 mg L-1 level. Good results were obtained in recovery tests using sample solutions from soil leaching and content tests according to the Japanese environmental quality standards for soil pollution."
1786493,Sonawane 2013,Chromium(VI) Catalyzed Oxidation of Primary Alcohol by Polymer Supported Reagent: A Kinetic and Mechanistic Approach,"The kinetic of chromium(VI) catalyzed oxidation of 1-phenyl ethanol has been studied by the rate of disappearance of [Cr(VI)]. The reaction is zero order with respect to [Cr(VI)]. The reagent supported on anion exchange resin was found to be more efficient in the oxidation reaction. The reagent is very easily separated from the reaction mixture and can be manually removed from the reaction mixture, which remains clear during and after the reaction. The kinetic of oxidation of 1-phenylethanol with chromic acid supported on anion exchange resin like Amberjet-4400 [Cl-] in 1,4-dioxane has been studied. The reaction is found to be of zero order each in concentration of alcohol and oxidant. The reaction Constants involved in the mechanism and the activation parameters have been calculated. There is a good agreement between observed and calculated rate constants under different experimental conditions. Acetophenone was detected as end product.","Chromium(VI) Catalyzed Oxidation of Primary Alcohol by Polymer Supported Reagent: A Kinetic and Mechanistic Approach Abs: The kinetic of chromium(VI) catalyzed oxidation of 1-phenyl ethanol has been studied by the rate of disappearance of [Cr(VI)]. The reaction is zero order with respect to [Cr(VI)]. The reagent supported on anion exchange resin was found to be more efficient in the oxidation reaction. The reagent is very easily separated from the reaction mixture and can be manually removed from the reaction mixture, which remains clear during and after the reaction. The kinetic of oxidation of 1-phenylethanol with chromic acid supported on anion exchange resin like Amberjet-4400 [Cl-] in 1,4-dioxane has been studied. The reaction is found to be of zero order each in concentration of alcohol and oxidant. The reaction Constants involved in the mechanism and the activation parameters have been calculated. There is a good agreement between observed and calculated rate constants under different experimental conditions. Acetophenone was detected as end product."
1786492,Shahzadi et al. 2013,EFFECT OF BACTERIA CONTAINING ACC DEAMINASE ON GROWTH OF WHEAT SEEDLINGS GROWN WITH CHROMIUM CONTAMINATED WATER,"Chromium (Cr) is considered as toxic environmental pollutant and causes harmful effects on growth and development of plants and human health. Usually, high level of ethylene (a plant hormone) is produced in plants in response to any biotic or abiotic stress. Negative effect of Cr-imposed stress on plants may be minimized by using bacteria possessing an enzyme 1-amino-cyclopropane-1-carboxylic acid (ACC)-deaminase. The aim of this study was to investigate the effect of plant growth-promoting bacteria containing ACC-deaminase on wheat under different levels of Cr applied to growth medium. Experiments were conducted under laboratory and lath house conditions. Results of this study demonstrated that inoculation of wheat seeds with two strains of bacteria Pseudomonas fluorescens (Q14) and Bacillus thuringiensis (KAP5) significantly increased the root length (up to 208%), shoot length (up to 67%), root dry weight (up to 140%) and shoot dry weight (up to 71%) respectively as compared to uninoculated control plants. Strain KAP5 possessing both ACC-deaminase as well as phosphate solubilizing activity was found to be the most effective in improving the plant growth compared to uninoculated control in both sand and soil experiments. Inoculation also significantly increased the accumulation of Cr in root and shoots compared to uninoculated control, where the Cr uptake 80.8 mu g/g dry mass and 69.9 mu g/g dry mass in root and shoot respectively, was observed. These findings indicated that ACC-deaminase producing bacterial strains could play vital role in improving the plant growth under metal-stress condition and they may enhance bioremediation process in Cr-contaminated environment. Moreover, presence of dual plant growth promoting trait such as ACC-deaminase and phosphate solubilizing activity could have more promising effect on plant growth and Cr removal than the single trait bacterium.","EFFECT OF BACTERIA CONTAINING ACC DEAMINASE ON GROWTH OF WHEAT SEEDLINGS GROWN WITH CHROMIUM CONTAMINATED WATER Abs: Chromium (Cr) is considered as toxic environmental pollutant and causes harmful effects on growth and development of plants and human health. Usually, high level of ethylene (a plant hormone) is produced in plants in response to any biotic or abiotic stress. Negative effect of Cr-imposed stress on plants may be minimized by using bacteria possessing an enzyme 1-amino-cyclopropane-1-carboxylic acid (ACC)-deaminase. The aim of this study was to investigate the effect of plant growth-promoting bacteria containing ACC-deaminase on wheat under different levels of Cr applied to growth medium. Experiments were conducted under laboratory and lath house conditions. Results of this study demonstrated that inoculation of wheat seeds with two strains of bacteria Pseudomonas fluorescens (Q14) and Bacillus thuringiensis (KAP5) significantly increased the root length (up to 208%), shoot length (up to 67%), root dry weight (up to 140%) and shoot dry weight (up to 71%) respectively as compared to uninoculated control plants. Strain KAP5 possessing both ACC-deaminase as well as phosphate solubilizing activity was found to be the most effective in improving the plant growth compared to uninoculated control in both sand and soil experiments. Inoculation also significantly increased the accumulation of Cr in root and shoots compared to uninoculated control, where the Cr uptake 80.8 mu g/g dry mass and 69.9 mu g/g dry mass in root and shoot respectively, was observed. These findings indicated that ACC-deaminase producing bacterial strains could play vital role in improving the plant growth under metal-stress condition and they may enhance bioremediation process in Cr-contaminated environment. Moreover, presence of dual plant growth promoting trait such as ACC-deaminase and phosphate solubilizing activity could have more promising effect on plant growth and Cr removal than the single trait bacterium."
1786491,Sahmurova et al. 2013,HEAVY METAL REMOVAL BY USING DRIED ENTEROMORPHA COMPRESSA MACRO ALGAE FROM AQUEOUS SOLUTION AND INDUSTRIAL WASTEWATER APPLICATION,"In this study adsorption of Zn (II) ions from aqueous solution was studied using Enteromorpha Compressa (EC) as an adsorbent. The FT-IR analysis results shows that EC biomass have several metal binding functional groups such as carboxyl and hydroxyl groups. The zero point of charge of the biomass was determined as pH 5.56 +/- 0.2. The optimum adsorption pH was determined at pH 6 and maximum adsorption capacity (Q(max)) of EC was determined as 625 mgg(-1). Adsorption capacity of biomass was increased with increase of the initial metal concentrations, however increasing the particle size range of biomass decreased the Zn (II) adsorption capacity. The pseudo second-order model well described the adsorption of Zn (II) on EC. The general using and efficiency of EC to treatment of industrial wastewater was tested. EC biomass effectively removed metal ions from industrial wastewater. contain 0.186 mgL(-1) of Cd, 0.034 mgL(-1) of Cu, 0.16 mgL(-1) of Zn ions. The the Chemical Oxygen Demand (COD) of industrial wastewater reduced after adsorption experiment from 886 to 729 mgL(-1) for sample 1 at pH 6.","HEAVY METAL REMOVAL BY USING DRIED ENTEROMORPHA COMPRESSA MACRO ALGAE FROM AQUEOUS SOLUTION AND INDUSTRIAL WASTEWATER APPLICATION Abs: In this study adsorption of Zn (II) ions from aqueous solution was studied using Enteromorpha Compressa (EC) as an adsorbent. The FT-IR analysis results shows that EC biomass have several metal binding functional groups such as carboxyl and hydroxyl groups. The zero point of charge of the biomass was determined as pH 5.56 +/- 0.2. The optimum adsorption pH was determined at pH 6 and maximum adsorption capacity (Q(max)) of EC was determined as 625 mgg(-1). Adsorption capacity of biomass was increased with increase of the initial metal concentrations, however increasing the particle size range of biomass decreased the Zn (II) adsorption capacity. The pseudo second-order model well described the adsorption of Zn (II) on EC. The general using and efficiency of EC to treatment of industrial wastewater was tested. EC biomass effectively removed metal ions from industrial wastewater. contain 0.186 mgL(-1) of Cd, 0.034 mgL(-1) of Cu, 0.16 mgL(-1) of Zn ions. The the Chemical Oxygen Demand (COD) of industrial wastewater reduced after adsorption experiment from 886 to 729 mgL(-1) for sample 1 at pH 6."
1786489,Reya et al. 2013,Equilibrium and Kinetic Studies on Biosorption of Cr (VI) using Novel Aspergillus Jegita isolated from Tannery Effluent,"The present work is concerned to remove Cr (VI) using the biosorption potential of the novel fungal biomass Aspergillus jegita isolated from tannery effluent. The dry fungal biomass was used to optimize various parameters such as contact time, initial metal ion concentration, pH, biomass loading etc. The percentage removal of chromium using various chemical pre-treatments was carried out. Maximum of 90.86% Cr (VI) removal was observed in 25 mg/L initial Cr (VI) metal ion concentration using dry Aspergillus jegita biomass. Maximum of 92.8% Cr (VI) removal was observed in 25 mg/L initial Cr (VI) metal ion concentration using dry alkali treated A. jegita biomass at 37 degrees C, pH 2.0 and 150 rpm. Further equilibrium modeling was carried out using Langmuir and Freundlich adsorption isotherm and the data were fitted. The kinetics of hexavalent chromium biosorption has been evaluated with respect to first order and second order kinetic equations. The characterization studies were carried out using SEM. The Cr (VI) metal was found to desorb effectively using 0.1M HCl and removal efficiency was found to be 96.3 % and can be recycled.","Equilibrium and Kinetic Studies on Biosorption of Cr (VI) using Novel Aspergillus Jegita isolated from Tannery Effluent Abs: The present work is concerned to remove Cr (VI) using the biosorption potential of the novel fungal biomass Aspergillus jegita isolated from tannery effluent. The dry fungal biomass was used to optimize various parameters such as contact time, initial metal ion concentration, pH, biomass loading etc. The percentage removal of chromium using various chemical pre-treatments was carried out. Maximum of 90.86% Cr (VI) removal was observed in 25 mg/L initial Cr (VI) metal ion concentration using dry Aspergillus jegita biomass. Maximum of 92.8% Cr (VI) removal was observed in 25 mg/L initial Cr (VI) metal ion concentration using dry alkali treated A. jegita biomass at 37 degrees C, pH 2.0 and 150 rpm. Further equilibrium modeling was carried out using Langmuir and Freundlich adsorption isotherm and the data were fitted. The kinetics of hexavalent chromium biosorption has been evaluated with respect to first order and second order kinetic equations. The characterization studies were carried out using SEM. The Cr (VI) metal was found to desorb effectively using 0.1M HCl and removal efficiency was found to be 96.3 % and can be recycled."
1786488,Rehman et al. 2013,Isothermal and Thermodynamical Modeling of Removing Cationic Dyes Through Biosorption Using Simple and Chemically Modified Eugenia jambolana Seeds as Biosorbent,"As biosorption is emerging as new waste water technique, the surge for new biosorbents is also increasing. Researchers are not only finding novel biosorbents, but they are also trying to modify them in order to enhance their biosorption capacity. In this study, the removal of methylene blue and brilliant green dyes from water had been studied using Eugenia jambolana seeds as biosorbent. Various factors which control the rate of biosorption process like biosorbent dose, pH of the dye solution, contact time interval, agitation rate and temperature are studied. Maximum biosorption capacity of chemically modified Eugenia jambolana seeds was 32.34 and 40.14 mg/g for methylene blue and Brilliant green dyes, respectively. Heats of biosorption were 6.5 and 9.21 kJ/mol for methylene blue and brilliant green dyes, respectively. Chemical modification of these seeds was made with tartaric acid in order to enhance their biosorption capacity. Desorption and thermodynamical parameters were also investigated. The results revealed that Eugenia jambolana seeds can be an effective biosorbent for removing dyes from waste water.","Isothermal and Thermodynamical Modeling of Removing Cationic Dyes Through Biosorption Using Simple and Chemically Modified Eugenia jambolana Seeds as Biosorbent Abs: As biosorption is emerging as new waste water technique, the surge for new biosorbents is also increasing. Researchers are not only finding novel biosorbents, but they are also trying to modify them in order to enhance their biosorption capacity. In this study, the removal of methylene blue and brilliant green dyes from water had been studied using Eugenia jambolana seeds as biosorbent. Various factors which control the rate of biosorption process like biosorbent dose, pH of the dye solution, contact time interval, agitation rate and temperature are studied. Maximum biosorption capacity of chemically modified Eugenia jambolana seeds was 32.34 and 40.14 mg/g for methylene blue and Brilliant green dyes, respectively. Heats of biosorption were 6.5 and 9.21 kJ/mol for methylene blue and brilliant green dyes, respectively. Chemical modification of these seeds was made with tartaric acid in order to enhance their biosorption capacity. Desorption and thermodynamical parameters were also investigated. The results revealed that Eugenia jambolana seeds can be an effective biosorbent for removing dyes from waste water."
1786487,Rao et al. 2013,"Hydrogeochemistry and groundwater quality assessment of Ranipet industrial area, Tamil Nadu, India","One of the highly polluted areas in India located at Ranipet occupies around 200 tanneries and other small scale chemical industries. Partially treated industrial effluents combined with sewage and other wastes discharged on the surface cause severe groundwater pollution in the industrial belt. This poses a problem of supply of safe drinking water in the rural parts of the country. A study was carried out to assess the groundwater pollution and identify major variables affecting the groundwater quality in Ranipet industrial area. Twenty five wells were monitored during pre- and post-monsoon in 2008 and analyzed for the major physico-chemical variables. The water quality variables such as total dissolved solids (TDS), Iron (Fe2+), Hexavalent Chromium (Cr6+), at most of the sampling locations exceeded the ISI and WHO guideline levels for drinking water. Multivariate statistical techniques such as factor analysis were applied to identify the major factors (variables) corresponding to the different source of variation in groundwater quality. The water quality of groundwater is influenced by both anthropogenic and chemical weathering. The most serious pollution threat to groundwater is from TDS, Cr6+ and Fe2+, which are associated with sewage and pollution of tannery waste. The study reveals that the groundwater quality changed due to anthropogenic and natural influences such as agricultural, natural weathering process.","Hydrogeochemistry and groundwater quality assessment of Ranipet industrial area, Tamil Nadu, India Abs: One of the highly polluted areas in India located at Ranipet occupies around 200 tanneries and other small scale chemical industries. Partially treated industrial effluents combined with sewage and other wastes discharged on the surface cause severe groundwater pollution in the industrial belt. This poses a problem of supply of safe drinking water in the rural parts of the country. A study was carried out to assess the groundwater pollution and identify major variables affecting the groundwater quality in Ranipet industrial area. Twenty five wells were monitored during pre- and post-monsoon in 2008 and analyzed for the major physico-chemical variables. The water quality variables such as total dissolved solids (TDS), Iron (Fe2+), Hexavalent Chromium (Cr6+), at most of the sampling locations exceeded the ISI and WHO guideline levels for drinking water. Multivariate statistical techniques such as factor analysis were applied to identify the major factors (variables) corresponding to the different source of variation in groundwater quality. The water quality of groundwater is influenced by both anthropogenic and chemical weathering. The most serious pollution threat to groundwater is from TDS, Cr6+ and Fe2+, which are associated with sewage and pollution of tannery waste. The study reveals that the groundwater quality changed due to anthropogenic and natural influences such as agricultural, natural weathering process."
1786486,Muneer et al. 2013,Tolerance and Biosorption of Mercury by Microbial Consortia: Potential Use in Bioremediation of Wastewater,"Mercury resistant microorganisms (bacteria, yeast and protozoa) were isolated from industrial effluents of tanneries and identified as Bacillus licheniformis, Candida parapsilosis and Tetrahymena rostrata on the basis of 16S rRNA and 18SrRNA gene sequence analysis. All microorganisms showed typical growth pattern except for the lag phase. The lag phase extended in the presence of mercury. Mercury processing ability of microorganisms was evaluated individually and in different combinations. B. licheniformis, C. parapsilosis and T. rostrata removed 73%, 80% and 40% of mercury, respectively, when used individually. B. licheniformis and C. parapsilosis reduced 85%, C. parapsilosis and T. rostrata removed, 77% and B. licheniformis and T. rostrata removed 73% mercury from the medium. Combination of three microorganisms viz., B. licheniformis, C. parapsilosis and T. rostrata when used simultaneously, removed 88% of Hg2+ after 96 h of incubation. It was concluded from this part of study that bacteria and yeast could make much more efficient inoculum for remediation of mercury-contaminated industrial waste water.","Tolerance and Biosorption of Mercury by Microbial Consortia: Potential Use in Bioremediation of Wastewater Abs: Mercury resistant microorganisms (bacteria, yeast and protozoa) were isolated from industrial effluents of tanneries and identified as Bacillus licheniformis, Candida parapsilosis and Tetrahymena rostrata on the basis of 16S rRNA and 18SrRNA gene sequence analysis. All microorganisms showed typical growth pattern except for the lag phase. The lag phase extended in the presence of mercury. Mercury processing ability of microorganisms was evaluated individually and in different combinations. B. licheniformis, C. parapsilosis and T. rostrata removed 73%, 80% and 40% of mercury, respectively, when used individually. B. licheniformis and C. parapsilosis reduced 85%, C. parapsilosis and T. rostrata removed, 77% and B. licheniformis and T. rostrata removed 73% mercury from the medium. Combination of three microorganisms viz., B. licheniformis, C. parapsilosis and T. rostrata when used simultaneously, removed 88% of Hg2+ after 96 h of incubation. It was concluded from this part of study that bacteria and yeast could make much more efficient inoculum for remediation of mercury-contaminated industrial waste water."
1786485,Mumtaz et al. 2013,Effect of Sechium edule on chemical induced kidney damage in experimental animals,"The aqueous extract of leaves of Sechium edule was evaluated for its protective activity against gentamicin, potassium dichromate-induced nephrotoxicity and streptozotocin-induced diabetic nephropathy in experimental animals. In these three conditions, the extract of S. edule (200 mg/kg) has significantly (p<0.001) decreased the level of blood urea, blood urea nitrogen and serum creatinine and also significantly (p<0.001) increased the serum levels of total protein. The serum uric acid level was also significantly (p<0.001) decrease in diabetic mice treated with the extract (200 mg/kg). The extract also improves the histology of the kidney. The results indicate that aqueous extract of leaves of S. edule has possessed protective effect against gentamicin- and potassium dichromate-induced nephrotoxicity and streptozotocin-induced diabetic nephropathy in experimental animals.","Effect of Sechium edule on chemical induced kidney damage in experimental animals Abs: The aqueous extract of leaves of Sechium edule was evaluated for its protective activity against gentamicin, potassium dichromate-induced nephrotoxicity and streptozotocin-induced diabetic nephropathy in experimental animals. In these three conditions, the extract of S. edule (200 mg/kg) has significantly (p<0.001) decreased the level of blood urea, blood urea nitrogen and serum creatinine and also significantly (p<0.001) increased the serum levels of total protein. The serum uric acid level was also significantly (p<0.001) decrease in diabetic mice treated with the extract (200 mg/kg). The extract also improves the histology of the kidney. The results indicate that aqueous extract of leaves of S. edule has possessed protective effect against gentamicin- and potassium dichromate-induced nephrotoxicity and streptozotocin-induced diabetic nephropathy in experimental animals."
1786484,Mohamad et al. 2013,Effect of Bifunctional Isocyanate Linker on Adsorption of Chromium(VI) Diphenylcarbazide Complex onto beta-Cyclodextrin,"Two polymers has been synthesized using bifunctional reagents of isocyanate group as crosslinking agent, which are beta-cyclodextrin polymer crosslinked hexamethylene diisocyanate (beta-CDP-HMDI) and beta-cyclodextrin polymer crosslinked toluene-2,4-diisocyanate (beta-CDP-TDI). The adsorption of Cr(VI) ions from aqueous solution by beta-cyclodextrin polymer (beta-CDP) as an adsorbent was studied in batch adsorption experiments. The method was based on the complex of Cr(VI) with 1,5-diphenylcarbazide (DPC) in acidic solution loaded on beta-CDP-HMDI and beta-CDP-TDI adsorbents. The adsorbents were characterized using Fourier transform infrared spectroscopy. The adsorption isotherm and kinetics of Cr(VI)-DPC complex onto both of beta-cyclodextrin polymer were studied. It showed that the Langmuir isotherm is better fit described the adsorption process for beta-CDP-HMDI, while Freundlich isotherm is better fit for beta-CDP-TDI. The pseudo second order kinetic model represented the adsorption process for both of beta-cyclodextrin polymer adsorbents. However, the rate constant of adsorption by beta-CDP-TDI was lower than beta-CDP-HMDI. The thermodynamic study showed that the enthalpy (Delta H degrees) value of beta-CDP-TDI was higher than beta-CDP-HMDI, indicated that beta-CDP-TDI has strong chemical bond with Cr(VI)-DPC. Furthermore, the value of free energy (Delta G degrees) and and entropy (Delta S degrees) showed that beta-CDP-TDI was more absorbable of Cr(IV)-DPC complexes than beta-CDP-HMDI. From these results, it was revealed that cross-linking agent is the main factor that contribute in the adsorption process of Cr(VI)-DPC complex onto beta-cyclodextrin polymer.","Effect of Bifunctional Isocyanate Linker on Adsorption of Chromium(VI) Diphenylcarbazide Complex onto beta-Cyclodextrin Abs: Two polymers has been synthesized using bifunctional reagents of isocyanate group as crosslinking agent, which are beta-cyclodextrin polymer crosslinked hexamethylene diisocyanate (beta-CDP-HMDI) and beta-cyclodextrin polymer crosslinked toluene-2,4-diisocyanate (beta-CDP-TDI). The adsorption of Cr(VI) ions from aqueous solution by beta-cyclodextrin polymer (beta-CDP) as an adsorbent was studied in batch adsorption experiments. The method was based on the complex of Cr(VI) with 1,5-diphenylcarbazide (DPC) in acidic solution loaded on beta-CDP-HMDI and beta-CDP-TDI adsorbents. The adsorbents were characterized using Fourier transform infrared spectroscopy. The adsorption isotherm and kinetics of Cr(VI)-DPC complex onto both of beta-cyclodextrin polymer were studied. It showed that the Langmuir isotherm is better fit described the adsorption process for beta-CDP-HMDI, while Freundlich isotherm is better fit for beta-CDP-TDI. The pseudo second order kinetic model represented the adsorption process for both of beta-cyclodextrin polymer adsorbents. However, the rate constant of adsorption by beta-CDP-TDI was lower than beta-CDP-HMDI. The thermodynamic study showed that the enthalpy (Delta H degrees) value of beta-CDP-TDI was higher than beta-CDP-HMDI, indicated that beta-CDP-TDI has strong chemical bond with Cr(VI)-DPC. Furthermore, the value of free energy (Delta G degrees) and and entropy (Delta S degrees) showed that beta-CDP-TDI was more absorbable of Cr(IV)-DPC complexes than beta-CDP-HMDI. From these results, it was revealed that cross-linking agent is the main factor that contribute in the adsorption process of Cr(VI)-DPC complex onto beta-cyclodextrin polymer."
1786483,Mishra and  Shoesmith 2013,The activation/depassivation of nickel-chromium-molybdenum alloys: An oxyanion or a pH effect-Part II,"The depletion of Cr and Mo in the passive films grown on commercial Ni-Cr-Mo(W) alloys in carbonate/bicarbonate solutions has been studied potentiodynamically and by X-ray photoelectron and Auger spectroscopy. Depletion in these two key alloying elements occurs at lower potentials than expected on all the alloys studied. It has been shown that the key feature leading to this behavior is the buffering of surface pH to >8.6, when the surface deposition (or retention) of insoluble protective Mo(VI) species does not occur as would be expected under the acidic local conditions generated by Cr(VI) and Mo(VI) dissolution. The presence of a small solution concentration of Mg2+ ions leads to the accumulation of a Mg(OH)(2) deposit when the surface pH is maintained sufficiently alkaline. (C) 2013 Elsevier Ltd. All rights reserved.","The activation/depassivation of nickel-chromium-molybdenum alloys: An oxyanion or a pH effect-Part II Abs: The depletion of Cr and Mo in the passive films grown on commercial Ni-Cr-Mo(W) alloys in carbonate/bicarbonate solutions has been studied potentiodynamically and by X-ray photoelectron and Auger spectroscopy. Depletion in these two key alloying elements occurs at lower potentials than expected on all the alloys studied. It has been shown that the key feature leading to this behavior is the buffering of surface pH to >8.6, when the surface deposition (or retention) of insoluble protective Mo(VI) species does not occur as would be expected under the acidic local conditions generated by Cr(VI) and Mo(VI) dissolution. The presence of a small solution concentration of Mg2+ ions leads to the accumulation of a Mg(OH)(2) deposit when the surface pH is maintained sufficiently alkaline. (C) 2013 Elsevier Ltd. All rights reserved."
1786482,Martinez-Delgadillo et al. 2013,Determination of the Spatial Distribution of the Turbulent Intensity and Velocity Field in an Electrochemical Reactor by CFD,"CFD simulations of a rotating reactor used to remove hexavalent chromium (Cr(VI)) from industrial wastewaters are presented in this work. The reaction time dependence on the angular speed was experimentally demonstrated and these results were examined using the flow velocity and turbulence intensity fields obtained by computational fluid dynamics (CFD) simulations. It was found out that the flow velocity field and turbulence intensity are not homogeneous inside the reactor. Moreover, the increase in the electrodes rotational speed has no important effect in the turbulence intensity and velocity field inside the ring electrodes zone, which helps explaining why the reaction time is not decreased in the same proportion of angular speed increment. The study provides reference aids for optimization of impeller design and operation parameters.","Determination of the Spatial Distribution of the Turbulent Intensity and Velocity Field in an Electrochemical Reactor by CFD Abs: CFD simulations of a rotating reactor used to remove hexavalent chromium (Cr(VI)) from industrial wastewaters are presented in this work. The reaction time dependence on the angular speed was experimentally demonstrated and these results were examined using the flow velocity and turbulence intensity fields obtained by computational fluid dynamics (CFD) simulations. It was found out that the flow velocity field and turbulence intensity are not homogeneous inside the reactor. Moreover, the increase in the electrodes rotational speed has no important effect in the turbulence intensity and velocity field inside the ring electrodes zone, which helps explaining why the reaction time is not decreased in the same proportion of angular speed increment. The study provides reference aids for optimization of impeller design and operation parameters."
1786481,Martinez-Delgadillo et al. 2013,Analysis by CFD Tool to Evaluate the Performance of a Tubular Electrochemical Flow Reactor with Rotating Anode,"In the present work, Computational Fluid Dynamics (CFD) analysis was used to evaluate the dispersion and visualize the velocity and vorticity field behavior along of a tubular electrochemical reactor in laminar flow regime, with a low speed-rotating anode operated. Five different reactor configurations to evaluate the performance of the reactor with rotating anode (cases C and D) in comparison with the reactor with static electrodes (cases A, B and E) were tested. Configurations A, E and C have three gaskets between the cathode and the anode. In the case E, the anode area was doubled to evaluate the effect on the reactor performance. At the same configuration, with and without gaskets (A versus C and B versus D) a substantial increase in the axial velocity (i.e. a reduction in the backwater), cell Reynolds number and spatial vorticity was achieved operating the reactor with the anode in rotation instead of static one. The improvement with the rotating anode could be related to the reduction of the axial flow barrier and disturbs on the fluid or chaotic flows induced by the motion of the rotating helical electrode. However, the percentage of negative velocities (backmixing) produced with the rotating anode, increased. The reactor with configuration E (static electrode and largest electrode area) showed the highest percentage of low axial velocities. On the other hand, in the flow electrochemical reactor with rotating anode, the backwater (low axial velocities +/- 0.0002 m/s), were reduced significantly. The vorticity and the cell Reynolds number were evaluated and both increased considerably when the anode was rotated during the electrochemical process, with and without gaskets. However, the percentage of negative velocities produced with the rotating electrode, increased until values higher than 55.25%.","Analysis by CFD Tool to Evaluate the Performance of a Tubular Electrochemical Flow Reactor with Rotating Anode Abs: In the present work, Computational Fluid Dynamics (CFD) analysis was used to evaluate the dispersion and visualize the velocity and vorticity field behavior along of a tubular electrochemical reactor in laminar flow regime, with a low speed-rotating anode operated. Five different reactor configurations to evaluate the performance of the reactor with rotating anode (cases C and D) in comparison with the reactor with static electrodes (cases A, B and E) were tested. Configurations A, E and C have three gaskets between the cathode and the anode. In the case E, the anode area was doubled to evaluate the effect on the reactor performance. At the same configuration, with and without gaskets (A versus C and B versus D) a substantial increase in the axial velocity (i.e. a reduction in the backwater), cell Reynolds number and spatial vorticity was achieved operating the reactor with the anode in rotation instead of static one. The improvement with the rotating anode could be related to the reduction of the axial flow barrier and disturbs on the fluid or chaotic flows induced by the motion of the rotating helical electrode. However, the percentage of negative velocities (backmixing) produced with the rotating anode, increased. The reactor with configuration E (static electrode and largest electrode area) showed the highest percentage of low axial velocities. On the other hand, in the flow electrochemical reactor with rotating anode, the backwater (low axial velocities +/- 0.0002 m/s), were reduced significantly. The vorticity and the cell Reynolds number were evaluated and both increased considerably when the anode was rotated during the electrochemical process, with and without gaskets. However, the percentage of negative velocities produced with the rotating electrode, increased until values higher than 55.25%."
1786480,Loss et al. 2013,Soil fertility and oxidizable and total carbon in Oxisol of the Cerrado under pasture irrigated and dryland,"The sprinkler irrigation on pasture can increase the forage production and improve soil chemical conditions. The aim of this study was to evaluate soil fertility and oxidizable and total carbon contents in Oxisol of the Cerrado under pasture area Tifton 85 (Cynodon spp), irrigated and dryland. The experimental design was completely randomized. Soil samples were collected in the 0-5, 5-10, 10-20 and 20-40cm depth, to evalueted the tenors of Ca, Mg, Al, P, K, Na, H + Al, total organic carbon (TOC) and determined the pH values. The samples were chemically fractionated with potassium dichromate to obtain fractions with different degrees of lability: F1>F2>F3>F4. The irrigated area had the highest Ca and Mg tenors in relation to the no-irrigated area, except for Mg, 10-20cm depth. It was observed difference for the TOC, and the highest values were verified in the irrigated area, due to higher contribution of stem and root biomass at all depths. This pattern was also observed for fractions F1 and F2. The irrigation increases the concentration of TOC, being this increase most noticeable in the more labile fractions (F1 and F2) and also provides improved soil fertility by increasing the concentration of Ca and Mg.","Soil fertility and oxidizable and total carbon in Oxisol of the Cerrado under pasture irrigated and dryland Abs: The sprinkler irrigation on pasture can increase the forage production and improve soil chemical conditions. The aim of this study was to evaluate soil fertility and oxidizable and total carbon contents in Oxisol of the Cerrado under pasture area Tifton 85 (Cynodon spp), irrigated and dryland. The experimental design was completely randomized. Soil samples were collected in the 0-5, 5-10, 10-20 and 20-40cm depth, to evalueted the tenors of Ca, Mg, Al, P, K, Na, H + Al, total organic carbon (TOC) and determined the pH values. The samples were chemically fractionated with potassium dichromate to obtain fractions with different degrees of lability: F1>F2>F3>F4. The irrigated area had the highest Ca and Mg tenors in relation to the no-irrigated area, except for Mg, 10-20cm depth. It was observed difference for the TOC, and the highest values were verified in the irrigated area, due to higher contribution of stem and root biomass at all depths. This pattern was also observed for fractions F1 and F2. The irrigation increases the concentration of TOC, being this increase most noticeable in the more labile fractions (F1 and F2) and also provides improved soil fertility by increasing the concentration of Ca and Mg."
1786479,Liu et al. 2013,"Synthesis and Crystal Structure of tris-(1,10-Phenanthroline)-Iron(II) Dichromate Tetrahydrate, Fe(C12H8N2)(3)Cr2O7 center dot 4H(2)O","In this report, Fe(C12H8N2)(3)Cr2O7 center dot 4H(2)O, was prepared by the reactor of FeCl2, 1,10-phenanthroline and potassium chromate. The asymmetric unit is composed of a [Fe(phen)(3)](2+) cation, a Cr2O72- anion and four water molecules. The metal centre is coordinated in a distorted octahedral mode by six N atoms from three 1,10-phenanthroline. The Cr2O72- anion is in a staggered conformation. The crystal packing is stabilized by intermolecular O-H center dot center dot center dot O and O-H center dot center dot center dot N hydrogen bonds and pi-pi interaction.","Synthesis and Crystal Structure of tris-(1,10-Phenanthroline)-Iron(II) Dichromate Tetrahydrate, Fe(C12H8N2)(3)Cr2O7 center dot 4H(2)O Abs: In this report, Fe(C12H8N2)(3)Cr2O7 center dot 4H(2)O, was prepared by the reactor of FeCl2, 1,10-phenanthroline and potassium chromate. The asymmetric unit is composed of a [Fe(phen)(3)](2+) cation, a Cr2O72- anion and four water molecules. The metal centre is coordinated in a distorted octahedral mode by six N atoms from three 1,10-phenanthroline. The Cr2O72- anion is in a staggered conformation. The crystal packing is stabilized by intermolecular O-H center dot center dot center dot O and O-H center dot center dot center dot N hydrogen bonds and pi-pi interaction."
1786478,Li et al. 2013,Influence of Fluoride and Chromium(VI) ions on Corrosion Mechanisms of Pb-3wt% Sn-0.5wt%Ag Anode,"A mix solution of fluorine and chromium ions (Cr-F solution) for applications in chromium plating field has a characteristic of strong corrosion and oxidation, promoting lead alloys anode degraded rapidly. The present study explores the time dependence on corrosion mechanisms of lead alloys anode oxidised in Cr-F solution under conditions of high current density. Scanning electron microscopy (SEM) with an energy dispersive X-ray spectroscopy (EDX) shows a double-layer oxide film is electrochemically developed on lead alloys anode after oxidation for above 0.5h. The outer layer is primarily PbO and PbO2, and the inner layer contains PbCrO4 and PbF2, followed by PbO. In the initial oxidation stage (oxidation time below 60s) of lead alloys anode, the Raman peaks of PbCrO4 and PbF2 are clearly shown by the Raman spectra scanning. With increasing reaction time, Raman peaks intensity for PbO is strengthened. Cyclic voltammetry reveals that effect of fluorine ions on the electrode potential for lead alloys anode change among Pb, PbO, PbCrO4, PbO1+x (0<x<1) and beta-PbO2. After oxidation treatment, electrochemical impedance spectroscopy (EIS) in 3g/L NH4F and/or 170g/L CrO3 solution indicates greater charge transfer resistance (R-t) for samples of longer oxidation time up until 2h. The corrosion mechanisms of the anode reaction at the anode/solution interface are discussed using the experimental results.","Influence of Fluoride and Chromium(VI) ions on Corrosion Mechanisms of Pb-3wt% Sn-0.5wt%Ag Anode Abs: A mix solution of fluorine and chromium ions (Cr-F solution) for applications in chromium plating field has a characteristic of strong corrosion and oxidation, promoting lead alloys anode degraded rapidly. The present study explores the time dependence on corrosion mechanisms of lead alloys anode oxidised in Cr-F solution under conditions of high current density. Scanning electron microscopy (SEM) with an energy dispersive X-ray spectroscopy (EDX) shows a double-layer oxide film is electrochemically developed on lead alloys anode after oxidation for above 0.5h. The outer layer is primarily PbO and PbO2, and the inner layer contains PbCrO4 and PbF2, followed by PbO. In the initial oxidation stage (oxidation time below 60s) of lead alloys anode, the Raman peaks of PbCrO4 and PbF2 are clearly shown by the Raman spectra scanning. With increasing reaction time, Raman peaks intensity for PbO is strengthened. Cyclic voltammetry reveals that effect of fluorine ions on the electrode potential for lead alloys anode change among Pb, PbO, PbCrO4, PbO1+x (0<x<1) and beta-PbO2. After oxidation treatment, electrochemical impedance spectroscopy (EIS) in 3g/L NH4F and/or 170g/L CrO3 solution indicates greater charge transfer resistance (R-t) for samples of longer oxidation time up until 2h. The corrosion mechanisms of the anode reaction at the anode/solution interface are discussed using the experimental results."
1786477,Kir et al. 2013,Removal of Cr(III) and Cu(II) using poly(2-chloroaniline)/polyvinylidenefluoride composite cation-exchange membranes by Donnan dialysis,"P2ClAn/PVDF composite membranes were prepared utilizing cation-exchange groups in the PVDF (polyvinylidenefluoride) membrane matrix by casting method. The poly(2-chloroaniline) (P2ClAn) was chemically synthesized with different dopant anions such as o-aminobenzene sulfonic acid (ABS) and sodium dodecyl sulfate (SDS). P2ClAn/PVDF membranes were extensively characterized for their surface morphology, thickness, ion-exchange capacity, SEM, AFM, and FTIR-ATR measurements. The SEM, AFM and FTIR-ATR pictures, comparing the original PVDF membrane support sheet to P2ClAn/PVDF composite membranes, indicate that the morphologies of the membranes are different. The membrane potential measurements were performed in various electrolyte solutions in order to observe the selectivity and stability of these membranes at different pHs. The P2ClAn/PVDF cation-exchange membranes were then used for the removal of chromium(III) and copper(II) ions from aqueous solution with Donnan dialysis. The flux values (J) of chromium(III) and copper(II) were obtained. The flux value of copper(II) ion was higher than chromium(III) for all of composite membranes because of the hydration volume.","Removal of Cr(III) and Cu(II) using poly(2-chloroaniline)/polyvinylidenefluoride composite cation-exchange membranes by Donnan dialysis Abs: P2ClAn/PVDF composite membranes were prepared utilizing cation-exchange groups in the PVDF (polyvinylidenefluoride) membrane matrix by casting method. The poly(2-chloroaniline) (P2ClAn) was chemically synthesized with different dopant anions such as o-aminobenzene sulfonic acid (ABS) and sodium dodecyl sulfate (SDS). P2ClAn/PVDF membranes were extensively characterized for their surface morphology, thickness, ion-exchange capacity, SEM, AFM, and FTIR-ATR measurements. The SEM, AFM and FTIR-ATR pictures, comparing the original PVDF membrane support sheet to P2ClAn/PVDF composite membranes, indicate that the morphologies of the membranes are different. The membrane potential measurements were performed in various electrolyte solutions in order to observe the selectivity and stability of these membranes at different pHs. The P2ClAn/PVDF cation-exchange membranes were then used for the removal of chromium(III) and copper(II) ions from aqueous solution with Donnan dialysis. The flux values (J) of chromium(III) and copper(II) were obtained. The flux value of copper(II) ion was higher than chromium(III) for all of composite membranes because of the hydration volume."
1786476,Khan et al. 2013,EFFECT OF MICROBIAL INOCULATION ON WHEAT GROWTH AND PHYTO-STABILIZATION OF CHROMIUM CONTAMINATED SOIL,"Higher concentration of Cr(VI) in the plant root zone affects many physiological processes and inhibits plant growth. Plant growth promoting rhizobacteria (PGPR) can improve plant health in contaminated soil as well as convert Cr(VI) to less toxic Cr(III). In this study, 180 Cr(VI) tolerant bacteria were isolated and after screening 10 efficient bacteria capable to work under chromium stress conditions were selected. Wheat (Triticum aestivum L.) seeds were inoculated with selected bacterial isolates and sown in Cr(VI) contaminated (20 mg kg(-1)) pots. Results showed that Cr(VI) contamination significantly suppressed the plant growth and development. However, inoculation improved plant growth parameters significantly compared to un-inoculated plants. In inoculated pots Cr(VI) contents were decreased in soil upto 62% while plant analysis for Cr(VI) revealed that inoculation decreased uptake and translocation of Cr(VI) from soil to the aerial parts of plant. Concentration of Cr(VI) was upto 36% less in roots and 60% less in shoots as compared to un-inoculated plants grown in contaminated pots.","EFFECT OF MICROBIAL INOCULATION ON WHEAT GROWTH AND PHYTO-STABILIZATION OF CHROMIUM CONTAMINATED SOIL Abs: Higher concentration of Cr(VI) in the plant root zone affects many physiological processes and inhibits plant growth. Plant growth promoting rhizobacteria (PGPR) can improve plant health in contaminated soil as well as convert Cr(VI) to less toxic Cr(III). In this study, 180 Cr(VI) tolerant bacteria were isolated and after screening 10 efficient bacteria capable to work under chromium stress conditions were selected. Wheat (Triticum aestivum L.) seeds were inoculated with selected bacterial isolates and sown in Cr(VI) contaminated (20 mg kg(-1)) pots. Results showed that Cr(VI) contamination significantly suppressed the plant growth and development. However, inoculation improved plant growth parameters significantly compared to un-inoculated plants. In inoculated pots Cr(VI) contents were decreased in soil upto 62% while plant analysis for Cr(VI) revealed that inoculation decreased uptake and translocation of Cr(VI) from soil to the aerial parts of plant. Concentration of Cr(VI) was upto 36% less in roots and 60% less in shoots as compared to un-inoculated plants grown in contaminated pots."
1786475,Kanwal et al. 2013,"Synthesis of Novel Composites of HCl-Doped Polyaniline with Maize, Rice and Wheat Flour","Polyaniline and its composites with rice, maize-and wheat flour were prepared at 0 and -5 degrees C by oxidative polymerization/of aniline in the presence of potassium dichromate as an Oxidizing agent. The prepared composites were characterized by fourier transform infrared. spectroscopy, UV-visible spectroscopy and standard four probe method. The UV-visible spectroscopy of the polyaniline composites show absorption maxima due to pi-pi* transition of the benzenoid ring and charge transfer excitations of the quinonoid structure, which are characteristics of emeraldhie base. FT-IR spectra of the polyaniline-composite is similar to that of pure polyaniline but with the shifts of bands to higher wave numbers due to strong interaction of dopants and polyaniline matrix. The conductivity measurements revealed that the conductance of polyaniline-maize composites offer-better conducting properties among all samples.","Synthesis of Novel Composites of HCl-Doped Polyaniline with Maize, Rice and Wheat Flour Abs: Polyaniline and its composites with rice, maize-and wheat flour were prepared at 0 and -5 degrees C by oxidative polymerization/of aniline in the presence of potassium dichromate as an Oxidizing agent. The prepared composites were characterized by fourier transform infrared. spectroscopy, UV-visible spectroscopy and standard four probe method. The UV-visible spectroscopy of the polyaniline composites show absorption maxima due to pi-pi* transition of the benzenoid ring and charge transfer excitations of the quinonoid structure, which are characteristics of emeraldhie base. FT-IR spectra of the polyaniline-composite is similar to that of pure polyaniline but with the shifts of bands to higher wave numbers due to strong interaction of dopants and polyaniline matrix. The conductivity measurements revealed that the conductance of polyaniline-maize composites offer-better conducting properties among all samples."
1786474,Jyothi et al. 2013,Analysis and Speciation of Chromium in Environmental Matrices by Various Analytical Techniques,"Chromium is a very important metal due to its use in various industries, such as dye', pigments and stainless steel Hexavalent chromium. is a earcinogen. Its deterinination in varionsTenvironmental Segments is -always a, Challenging issue for environmental researchers. In this concern first section of this review article :gives a brief history of chromium, such as its oxidationstates, production information, uses, biological importance, exposure pathways and regulatory concentration levels. The second section explains aboutthe sources of chromium and the next section gives the details of health effects and toxicity caused due to the presence Of chromium in various environmental segments. Finally this paper.discusses the determination, of chroiniunt in different biological and environmental samples various analytical technique, suchas-atomic absorption spectrorneter, Spectrophotometet, Voltammeter, Inductively coupled plasma techniques (ICP-AES, OS), potentiometer, spectrofluorometer, HPLC/GC-MS and cherailurninescence reported by the researchers worldwide sine 2006. All the data collected during the literature survey is tabulated; which gives important information about the.analytieal methods and techniques used for the chromium determination.","Analysis and Speciation of Chromium in Environmental Matrices by Various Analytical Techniques Abs: Chromium is a very important metal due to its use in various industries, such as dye', pigments and stainless steel Hexavalent chromium. is a earcinogen. Its deterinination in varionsTenvironmental Segments is -always a, Challenging issue for environmental researchers. In this concern first section of this review article :gives a brief history of chromium, such as its oxidationstates, production information, uses, biological importance, exposure pathways and regulatory concentration levels. The second section explains aboutthe sources of chromium and the next section gives the details of health effects and toxicity caused due to the presence Of chromium in various environmental segments. Finally this paper.discusses the determination, of chroiniunt in different biological and environmental samples various analytical technique, suchas-atomic absorption spectrorneter, Spectrophotometet, Voltammeter, Inductively coupled plasma techniques (ICP-AES, OS), potentiometer, spectrofluorometer, HPLC/GC-MS and cherailurninescence reported by the researchers worldwide sine 2006. All the data collected during the literature survey is tabulated; which gives important information about the.analytieal methods and techniques used for the chromium determination."
1786473,Iqbal et al. 2013,Kinetic Study of Cr(III) and Cr(VI) Biosorption Using Rosa damascena Phytomass: A Rose Waste Biomass,"In present study, Cr(III) and Cr(VI) sorption capacity of Rosa damascena phytomass from aqueous solution was evaluated. The R. damascena phytomass biosorption revealed that smaller biosorbent size (< 0.4 g), dose (< 0.1 g), pH (2 and 5 for Cr VI and III) and 100 mg L-1 initial metal concentration were more suitable for better biosorption from aqueous medium. The Langmuir isotherm model and pseudo second order kinetic model fitted well to the data of Cr(III) and Cr(VI) biosorption. The negative value of Gibbs free energy (Delta G degrees) indicated the spontaneous absorption process. The R. damascena biomass pre-treatment enhanced biosorption considerably and it is concluded that the R. damascena biomass (waste material) might be used for biosorption of Cr(III) and Cr(VI) from aqueous solution.","Kinetic Study of Cr(III) and Cr(VI) Biosorption Using Rosa damascena Phytomass: A Rose Waste Biomass Abs: In present study, Cr(III) and Cr(VI) sorption capacity of Rosa damascena phytomass from aqueous solution was evaluated. The R. damascena phytomass biosorption revealed that smaller biosorbent size (< 0.4 g), dose (< 0.1 g), pH (2 and 5 for Cr VI and III) and 100 mg L-1 initial metal concentration were more suitable for better biosorption from aqueous medium. The Langmuir isotherm model and pseudo second order kinetic model fitted well to the data of Cr(III) and Cr(VI) biosorption. The negative value of Gibbs free energy (Delta G degrees) indicated the spontaneous absorption process. The R. damascena biomass pre-treatment enhanced biosorption considerably and it is concluded that the R. damascena biomass (waste material) might be used for biosorption of Cr(III) and Cr(VI) from aqueous solution."
1786472,Ilyas et al. 2013,Removal of Cr (VI) from Aqueous Solutions Using Peanut shell as Adsorbent,"The biosorption of Cr (VI) ions from aqueous solution by peanut shell (PNS) biosorbent was studied in a batch mode system. Factors affecting Cr (VI) biosorption such as pH (2-7), initial chromium ion concentrations (20-60 mg/l), contact time (6 h), adsorbent dosage (0.2-1.0 g) and temperature (293-313 K) were investigated. The adsorption equilibrium was established at 360 minutes. A comparison of the kinetic models has showed that pseudo-second order equation best described adsorption kinetics. Maximum adsorption was achieved at pH 2.0 and 3.0. The adsorption equilibrium data was fitted well to the Langmuir adsorption isotherm as compared to the Freundlich adsorption isotherm. The values of separation factor, R-L, was found between 0.0235 and 0.0633 (0 < R-L< 1) which pointed out favorable adsorption of Cr (VI) on PNS adsorbent. The adsorption capacity was measured in terms of monolayer adsorption and was found to be 4.32 mg/g at 313 K. The thermodynamic parameters (Delta G, Delta H and Delta S) values indicated the endothermic, non spontaneous and entropy driven system of the adsorption process.","Removal of Cr (VI) from Aqueous Solutions Using Peanut shell as Adsorbent Abs: The biosorption of Cr (VI) ions from aqueous solution by peanut shell (PNS) biosorbent was studied in a batch mode system. Factors affecting Cr (VI) biosorption such as pH (2-7), initial chromium ion concentrations (20-60 mg/l), contact time (6 h), adsorbent dosage (0.2-1.0 g) and temperature (293-313 K) were investigated. The adsorption equilibrium was established at 360 minutes. A comparison of the kinetic models has showed that pseudo-second order equation best described adsorption kinetics. Maximum adsorption was achieved at pH 2.0 and 3.0. The adsorption equilibrium data was fitted well to the Langmuir adsorption isotherm as compared to the Freundlich adsorption isotherm. The values of separation factor, R-L, was found between 0.0235 and 0.0633 (0 < R-L< 1) which pointed out favorable adsorption of Cr (VI) on PNS adsorbent. The adsorption capacity was measured in terms of monolayer adsorption and was found to be 4.32 mg/g at 313 K. The thermodynamic parameters (Delta G, Delta H and Delta S) values indicated the endothermic, non spontaneous and entropy driven system of the adsorption process."
1786471,Holda et al. 2013,Bioaccumulation of Cr(VI) Ions from Aqueous Solutions by Penicillium citrinum,,Bioaccumulation of Cr(VI) Ions from Aqueous Solutions by Penicillium citrinum Abs: 
1786470,Holda and  Kisielowska 2013,BIOLOGICAL REMOVAL OF Cr(VI) IONS FROM AQUEOUS SOLUTIONS BY TRICHODERMA VIRIDE,"The paper presents biological removing of Cr(VI) ions from aqueous solution by applying autochtonic fungi seedling of Trichoderma viride originated from chromium mud samples. The growth of organism and removing of chromium(VI) was performed in aqueous solution of various chromium(VI) contents and at optimal value of pH. During 14 days of incubation, samples of 5 cm(3) each were collected every day for determination of chromium(VI) in solution and the efficiency of biological removal was specified. Since removal of chromium(VI) from aqueous solution may occur because of reduction, biosorption or bioaccumulation processes, to determine which one occurred, the Cr(III) contents were determined in samples of the medium as well in ooze after mycelium irrigating and in mycelium.","BIOLOGICAL REMOVAL OF Cr(VI) IONS FROM AQUEOUS SOLUTIONS BY TRICHODERMA VIRIDE Abs: The paper presents biological removing of Cr(VI) ions from aqueous solution by applying autochtonic fungi seedling of Trichoderma viride originated from chromium mud samples. The growth of organism and removing of chromium(VI) was performed in aqueous solution of various chromium(VI) contents and at optimal value of pH. During 14 days of incubation, samples of 5 cm(3) each were collected every day for determination of chromium(VI) in solution and the efficiency of biological removal was specified. Since removal of chromium(VI) from aqueous solution may occur because of reduction, biosorption or bioaccumulation processes, to determine which one occurred, the Cr(III) contents were determined in samples of the medium as well in ooze after mycelium irrigating and in mycelium."
1786469,Hlihor et al. 2013,Bioremediation of Cr(VI) Polluted Wastewaters by Sorption on Heat Inactivated Saccharomyces cerevisiae Biomass,"The potential of heat inactivated Saccharomyces cerevisiae in the bioremoval and reduction of Cr (VI) ions from wastewaters was evaluated in terms of metal uptake in time and at equilibrium, and biosorption efficiency, by varying pH, biosorbent doses, contact time and temperature, in batch mode. During the sorption process, the heat inactivated biomass of the yeast Saccharomyces cerevisiae is capable of reducing Cr(VI) to Cr(III). Different kinetic models based on adsorption and reduction are used to represent the kinetic data of Cr(VI) bioremoval by S. cerevisiae, in explaining the biosorption mechanism of heavy metals and potential rate-controlling steps, in the perspective of fill-scale process design. The results indicated some potential differences in the Cr(VI) removal mechanism at different experimental conditions. FTIR and SEM analysis were performed as well as to elucidate the mechanism of metal bioremoval by S. cerevisiae. FTIR spectra indicate that heavy metal bioremoval process doesn't imply in this case the formation of stable covalent bonds, but it is predominantly based on chemical interactions, ion-exchange type. The SEM micrographs of Cr-loaded yeast, indicates that the surface morphology doesn't change much after chromium ions were uptaken. This leads to the conclusion that Cr(VI) reduction occurs at the interface of the adsorbent.","Bioremediation of Cr(VI) Polluted Wastewaters by Sorption on Heat Inactivated Saccharomyces cerevisiae Biomass Abs: The potential of heat inactivated Saccharomyces cerevisiae in the bioremoval and reduction of Cr (VI) ions from wastewaters was evaluated in terms of metal uptake in time and at equilibrium, and biosorption efficiency, by varying pH, biosorbent doses, contact time and temperature, in batch mode. During the sorption process, the heat inactivated biomass of the yeast Saccharomyces cerevisiae is capable of reducing Cr(VI) to Cr(III). Different kinetic models based on adsorption and reduction are used to represent the kinetic data of Cr(VI) bioremoval by S. cerevisiae, in explaining the biosorption mechanism of heavy metals and potential rate-controlling steps, in the perspective of fill-scale process design. The results indicated some potential differences in the Cr(VI) removal mechanism at different experimental conditions. FTIR and SEM analysis were performed as well as to elucidate the mechanism of metal bioremoval by S. cerevisiae. FTIR spectra indicate that heavy metal bioremoval process doesn't imply in this case the formation of stable covalent bonds, but it is predominantly based on chemical interactions, ion-exchange type. The SEM micrographs of Cr-loaded yeast, indicates that the surface morphology doesn't change much after chromium ions were uptaken. This leads to the conclusion that Cr(VI) reduction occurs at the interface of the adsorbent."
1786468,Guo et al. 2013,Performance of binding interaction between Cr(VI) and serum proteome,"The binding reaction between heavy metal ions Cr(VI) and serum proteome was investigated using affinity capillary electrophoresis (ACE) method. Based on the site binding model, a model about the interaction between Cr(VI) as the ligand and FBS as the receptor, was established. The binding performance of heavy metal ions Cr(VI) and the serum proteome was studied under proteomic conditions, and the results showed that, Cr(VI)-protein complexes formed between Cr(VI) and the high abundance component albumin in FBS, such as albumin (bovine serum albumin, BSA), transferrin protein (Bovine apo transferrin, bATF), immunogolobulin (Bovine IgG, IgG) and so on, and the binding reactions of Cr(VI) -FBS are fast equilibrium reactions. The apparent binding constant was determined through non-linear fitting binding reaction and based on changes of the effective mobility, and KCr(VI)-bATF=1.27x10(4) L.mol(-1), KCr(VI)-IgG=4.91x10(4) L.mol(-1), KCr(VI)-BSA=8.98x10(4) L.mol(-1). Dosage-dependent effect exists among the concentration of Cr(VI) and the strength of the binding reactions. This work has referential meaning for understanding deeply the binding reaction mechanism of chromium(VI) with serum proteome.","Performance of binding interaction between Cr(VI) and serum proteome Abs: The binding reaction between heavy metal ions Cr(VI) and serum proteome was investigated using affinity capillary electrophoresis (ACE) method. Based on the site binding model, a model about the interaction between Cr(VI) as the ligand and FBS as the receptor, was established. The binding performance of heavy metal ions Cr(VI) and the serum proteome was studied under proteomic conditions, and the results showed that, Cr(VI)-protein complexes formed between Cr(VI) and the high abundance component albumin in FBS, such as albumin (bovine serum albumin, BSA), transferrin protein (Bovine apo transferrin, bATF), immunogolobulin (Bovine IgG, IgG) and so on, and the binding reactions of Cr(VI) -FBS are fast equilibrium reactions. The apparent binding constant was determined through non-linear fitting binding reaction and based on changes of the effective mobility, and KCr(VI)-bATF=1.27x10(4) L.mol(-1), KCr(VI)-IgG=4.91x10(4) L.mol(-1), KCr(VI)-BSA=8.98x10(4) L.mol(-1). Dosage-dependent effect exists among the concentration of Cr(VI) and the strength of the binding reactions. This work has referential meaning for understanding deeply the binding reaction mechanism of chromium(VI) with serum proteome."
1786467,Georgieva et al. 2013,PVA-BASED HYBRID MATERIALS FOR IMMOBILIZATION OF TRICHOSPORON CUTANEUM R57 EFFICIENT IN REMOVAL OF CHROMIUM IONS,"New hybrid materials based on polyvinyl alcohol (PVA) and gamma-aminopropyltriethoxyxilane (APTEOS), 3-mercaptopropyltriethoxysilane (MPTEOS) and tetraethoxysilane (TEOS) were prepared. To determine the thermal stability of the hybrid materials, thermogravimetric analysis (TGA) was performed. The new materials were tested for biofilm formation and biosorption studies. They were tested as matrices for immobilization of Trichosporon cutaneum R57 capable to remove Cr(VI) from aqueous solutions. The use of APTEOS and MPTEOS as precursors, incorporated new NH- and SH- bonds, which ensured additional binding places for cells immobilization. The presence of SH- and NH- groups in the hybrid matrices resulted in apparently higher Cr(VI) sorption capacity of the immobilized Tr. cutaneum R57 cells due to the incorporation of additional adsorption sites in the matrix through the PVA functionalities. The synthesized PVA/APTEOS materials proved efficient for use in biosorption applications.","PVA-BASED HYBRID MATERIALS FOR IMMOBILIZATION OF TRICHOSPORON CUTANEUM R57 EFFICIENT IN REMOVAL OF CHROMIUM IONS Abs: New hybrid materials based on polyvinyl alcohol (PVA) and gamma-aminopropyltriethoxyxilane (APTEOS), 3-mercaptopropyltriethoxysilane (MPTEOS) and tetraethoxysilane (TEOS) were prepared. To determine the thermal stability of the hybrid materials, thermogravimetric analysis (TGA) was performed. The new materials were tested for biofilm formation and biosorption studies. They were tested as matrices for immobilization of Trichosporon cutaneum R57 capable to remove Cr(VI) from aqueous solutions. The use of APTEOS and MPTEOS as precursors, incorporated new NH- and SH- bonds, which ensured additional binding places for cells immobilization. The presence of SH- and NH- groups in the hybrid matrices resulted in apparently higher Cr(VI) sorption capacity of the immobilized Tr. cutaneum R57 cells due to the incorporation of additional adsorption sites in the matrix through the PVA functionalities. The synthesized PVA/APTEOS materials proved efficient for use in biosorption applications."
1786466,Fan et al. 2013,Separation and recovery of chromium and vanadium from vanadium-containing chromate solution by ion exchange,"To recover vanadium from vanadium-containing chromate solution, the separation of vanadium from chromium using the weak base resin D314 both in batch and column test was studied. Experimental results showed that in the pH range of 2.5-6.5, by double-adsorption with the resin, vanadium and chromium can be completely separated and recovered from vanadium-containing chromate solution. In the adsorption of vanadium, the bed volume reached 20 using the vanadium-containing chromate solution containing 2.21 g/L V2O5 and 3.89 g/L Cr2O3 under pH 6.45 at 25 degrees C for contact time of 60 min. The loaded resin was easily stripped using 2 mol/L NaOH solution, resulting in 106.83 g/L V2O5 and only 0.11 g/L Cr2O3 in strip liquor. The chromium in the effluent was then recovered using the same resin, and the final product of Cr2O3 with purity of 99.2% was obtained from the chromium strip liquor by reduction and precipitation. (C) 2013 Elsevier B.V. All rights reserved.","Separation and recovery of chromium and vanadium from vanadium-containing chromate solution by ion exchange Abs: To recover vanadium from vanadium-containing chromate solution, the separation of vanadium from chromium using the weak base resin D314 both in batch and column test was studied. Experimental results showed that in the pH range of 2.5-6.5, by double-adsorption with the resin, vanadium and chromium can be completely separated and recovered from vanadium-containing chromate solution. In the adsorption of vanadium, the bed volume reached 20 using the vanadium-containing chromate solution containing 2.21 g/L V2O5 and 3.89 g/L Cr2O3 under pH 6.45 at 25 degrees C for contact time of 60 min. The loaded resin was easily stripped using 2 mol/L NaOH solution, resulting in 106.83 g/L V2O5 and only 0.11 g/L Cr2O3 in strip liquor. The chromium in the effluent was then recovered using the same resin, and the final product of Cr2O3 with purity of 99.2% was obtained from the chromium strip liquor by reduction and precipitation. (C) 2013 Elsevier B.V. All rights reserved."
1786465,Cheng et al. 2013,"Groundwater quality and the potentiality in health risk assessment in Zhengzhou, China","Groundwater quality and suitability for drinking purposes in Zhengzhou City were investigated. A total of 30 water samples from 15 major monitoring wells were collected in January (dry season) and July (wet season), 2009. Seven common physicochemical (pH, permanganate index, ammonia, chloride, sulfate, hardness and the total dissolved solids) and 11 toxicological parameters (fluorine, nitrate, Zn, Fe, Mn, Cu, Cd, Pb, Se, Cr (VI) and As) were analyzed. Human health risk assessment for pollutants and water quality index for drinking purposes were also evaluated. The results showed that 6.7% of groundwater samples were considered as permissible for drinking and others as desirable; concentrations of chromium (VI) at site 14 and 15 were lower than the risk-based concentration associated non-carcinogenic effects (0.11mg l(1)), while higher than the standard associated carcinogenic effects (4.5E-5mg l(1)). The carcinogenic risk was 3.75E-6 at site 14 and 4.55E-6 at site 15, which indicated that the risks at both sites were serious. The uncontrolled consumption of poor quality groundwater may be dangerous for local human health. Concentrations of other elements were not detected nor found to be exceeding the highest acceptable limit of World Health Organization. Water quality index indicated that the quality of all the groundwater samples collected was excellent during both dry and wet seasons. Lower water quality indices during the wet season indicated a better quality of the groundwater than the dry season, and the main reasons were external input following seasonal rainfall events and evaporation. Significant variation of water chemistry strongly expressed the impact of surface contamination sources, overexploitation and mineral dissolution.","Groundwater quality and the potentiality in health risk assessment in Zhengzhou, China Abs: Groundwater quality and suitability for drinking purposes in Zhengzhou City were investigated. A total of 30 water samples from 15 major monitoring wells were collected in January (dry season) and July (wet season), 2009. Seven common physicochemical (pH, permanganate index, ammonia, chloride, sulfate, hardness and the total dissolved solids) and 11 toxicological parameters (fluorine, nitrate, Zn, Fe, Mn, Cu, Cd, Pb, Se, Cr (VI) and As) were analyzed. Human health risk assessment for pollutants and water quality index for drinking purposes were also evaluated. The results showed that 6.7% of groundwater samples were considered as permissible for drinking and others as desirable; concentrations of chromium (VI) at site 14 and 15 were lower than the risk-based concentration associated non-carcinogenic effects (0.11mg l(1)), while higher than the standard associated carcinogenic effects (4.5E-5mg l(1)). The carcinogenic risk was 3.75E-6 at site 14 and 4.55E-6 at site 15, which indicated that the risks at both sites were serious. The uncontrolled consumption of poor quality groundwater may be dangerous for local human health. Concentrations of other elements were not detected nor found to be exceeding the highest acceptable limit of World Health Organization. Water quality index indicated that the quality of all the groundwater samples collected was excellent during both dry and wet seasons. Lower water quality indices during the wet season indicated a better quality of the groundwater than the dry season, and the main reasons were external input following seasonal rainfall events and evaporation. Significant variation of water chemistry strongly expressed the impact of surface contamination sources, overexploitation and mineral dissolution."
1786464,Chen et al. 2013,Online spectrophtometric determination of Cr(III) and Cr(VI) in tannery wastewater using flow injection combined with low pressure ion chromatography,"Highly selective, low-cost and easily operating method has been developed for online separation and simultaneous determination of Cr (III) and Cr (VI) by using low pressure ion chromatography combined with flow injection spectrophtometric analysis(LPIC-FIA). Based on the selective adsorption of low pressure ion chromatographic column (LPICC) on Cr(III), a new online separation system of Cr(III) and Cr(VI) was proposed. Thus, the separated Cr(VI) and Cr(III) successively reacted with salicylfluorone(SAF) to form amaranthine complex in the presence of cetyltrimethylmmonium bromide (CTMAB), respectively. The complex gave maximum absorbance at 570 nm. All the variables were studied in order to optimize the reaction conditions. The calibration graphs were linear in the range of 10-1000 mu g L-1 (Cr(III)) and 5-1000 mu g L-1 (Cr(VI)) with correlation coefficients of 0.9996 and 0.9993 respectively. The R. S. D. obtained for 200 mu g L-1 of Cr(III) and 100 g L-1 of Cr(VI) was 2.36 % (n=12) and 2.17 %, respectively. The method was applied for the simultaneous determination of Cr(III) and Cr(VI) in tannery wastewater with satisfactory results and recoveries in the range of 95.8%-104.6% and 96.5 %-104.6 % respectively.","Online spectrophtometric determination of Cr(III) and Cr(VI) in tannery wastewater using flow injection combined with low pressure ion chromatography Abs: Highly selective, low-cost and easily operating method has been developed for online separation and simultaneous determination of Cr (III) and Cr (VI) by using low pressure ion chromatography combined with flow injection spectrophtometric analysis(LPIC-FIA). Based on the selective adsorption of low pressure ion chromatographic column (LPICC) on Cr(III), a new online separation system of Cr(III) and Cr(VI) was proposed. Thus, the separated Cr(VI) and Cr(III) successively reacted with salicylfluorone(SAF) to form amaranthine complex in the presence of cetyltrimethylmmonium bromide (CTMAB), respectively. The complex gave maximum absorbance at 570 nm. All the variables were studied in order to optimize the reaction conditions. The calibration graphs were linear in the range of 10-1000 mu g L-1 (Cr(III)) and 5-1000 mu g L-1 (Cr(VI)) with correlation coefficients of 0.9996 and 0.9993 respectively. The R. S. D. obtained for 200 mu g L-1 of Cr(III) and 100 g L-1 of Cr(VI) was 2.36 % (n=12) and 2.17 %, respectively. The method was applied for the simultaneous determination of Cr(III) and Cr(VI) in tannery wastewater with satisfactory results and recoveries in the range of 95.8%-104.6% and 96.5 %-104.6 % respectively."
1786463,Cai et al. 2013,Synthesis and Characterization of Chromate Cu(II)/Ni(II) Chain Complexes,"Two new one-dimensional chain complexes, (NH4)(2) [Cu(NH3)(2)(CrO4)(2)] (1) and (NH4)(2) center dot Ni(NH3)(2)(Cr-4)(2) (2), were obtained by mixing copper nitrate or nickel nitrate with the same molar of ammonium dichromate in ammonia water at room temperature, and they were characterized by single-crystal Xray diffraction(XRD), thermogravimetric analysis (TGA) and differential thermal analysis (DTA). Furthermore, the complexes were magnetically characterized by temperature-dependent magnetic susceptibility, fielddependent magnetization, and alternate current(AC) magnetic measurements. The structure analysis results show that crystals of both complexes are triclinic, space group P1 ($) over bar with a =0. 59090(12) nm, b = 0. 6929(3) nm, c= 0. 73740(15) nm, alpha = 107. 03 (4)degrees, beta = 92. 79 (3)degrees, gamma = 112. 44 (2)degrees for Cu (II) complex and a=0.56987(7) nm, b = 0. 69972 (9) nm, c = O. 73335 (8) nm, = 104. 929 (3), p = 96. 7121 (3), y=112. 325(4) for Ni(II) complex. In the crystal structure, the [M (NH3)(2))(2+) units are linked by two chromato bridges, forming an eight-member ring. As a whole, both complexes have one-dimensional chain structures. The two complexes began to break down as the temperature gradually reached 150 C or so, leaving behind H2Cr2CuO5 and H2Cr2 NiO5, and afterwards they are dehydrated at above 410 degrees C. The temperature-dependent magnetic susceptibilities were measured in the range of 2-300 K, which implies a weak antiferromagnetic interaction between the adjacent mental ions. The field-dependent magnetization and AC magnetic measurements indicate that the two complexes are both antiferromagnets.","Synthesis and Characterization of Chromate Cu(II)/Ni(II) Chain Complexes Abs: Two new one-dimensional chain complexes, (NH4)(2) [Cu(NH3)(2)(CrO4)(2)] (1) and (NH4)(2) center dot Ni(NH3)(2)(Cr-4)(2) (2), were obtained by mixing copper nitrate or nickel nitrate with the same molar of ammonium dichromate in ammonia water at room temperature, and they were characterized by single-crystal Xray diffraction(XRD), thermogravimetric analysis (TGA) and differential thermal analysis (DTA). Furthermore, the complexes were magnetically characterized by temperature-dependent magnetic susceptibility, fielddependent magnetization, and alternate current(AC) magnetic measurements. The structure analysis results show that crystals of both complexes are triclinic, space group P1 ($) over bar with a =0. 59090(12) nm, b = 0. 6929(3) nm, c= 0. 73740(15) nm, alpha = 107. 03 (4)degrees, beta = 92. 79 (3)degrees, gamma = 112. 44 (2)degrees for Cu (II) complex and a=0.56987(7) nm, b = 0. 69972 (9) nm, c = O. 73335 (8) nm, = 104. 929 (3), p = 96. 7121 (3), y=112. 325(4) for Ni(II) complex. In the crystal structure, the [M (NH3)(2))(2+) units are linked by two chromato bridges, forming an eight-member ring. As a whole, both complexes have one-dimensional chain structures. The two complexes began to break down as the temperature gradually reached 150 C or so, leaving behind H2Cr2CuO5 and H2Cr2 NiO5, and afterwards they are dehydrated at above 410 degrees C. The temperature-dependent magnetic susceptibilities were measured in the range of 2-300 K, which implies a weak antiferromagnetic interaction between the adjacent mental ions. The field-dependent magnetization and AC magnetic measurements indicate that the two complexes are both antiferromagnets."
1786461,Basu et al. 2013,Micellar Catalysis of Chromic Acid Oxidation of Methionine to Industrially Important Methylthiol in Aqueous Media at Room Temperature,"Oxidation of organic molecule by metal is very important. Selective oxidants require non aqueous media, which is toxic and hazardous. L-methionine is oxidized to industrially important methyl thiol in micellar media by chromic acid. The overall reaction follows a first order dependency on substrate and hexavalent chromium and second order dependency on hydrogen ion. Here, reverse micelle formation is observed. TX-100 increases the rate where as SDS retards the rate of oxidation.","Micellar Catalysis of Chromic Acid Oxidation of Methionine to Industrially Important Methylthiol in Aqueous Media at Room Temperature Abs: Oxidation of organic molecule by metal is very important. Selective oxidants require non aqueous media, which is toxic and hazardous. L-methionine is oxidized to industrially important methyl thiol in micellar media by chromic acid. The overall reaction follows a first order dependency on substrate and hexavalent chromium and second order dependency on hydrogen ion. Here, reverse micelle formation is observed. TX-100 increases the rate where as SDS retards the rate of oxidation."
1786460,Baral et al. 2013,STATISTICAL DESIGN OF EXPERIMENTS FOR THE Cr(VI) ADSORPTION ON WEED Salvinia cucullata,"Experiments were designed to optimize the Cr(VI) adsorption on Salvinia cucullata. The significance of different adsorption parameters along with their combined effect on the adsorption process has been established. A regression equation was formulated by representing percentage of Cr(VI) adsorption as a function of different independent variables such as contact time, pH, adsorbate concentration and adsorbent dose. The insignificant terms were assessed through student 't' test and are removed from the regression equation. The resulting regression equation after removal of the insignificant terms was verified by using Fisher's adequacy test. The pH coefficient was the most dominant followed by adsorbate concentration and contact time. Adsorbent dose induces a small effect on adsorption process. Among the interaction term combined effect of contact time and adsorbate concentration has the most influential effect followed by combined effect of time, pH and adsorbate concentration. Combined effect of pH and adsorbate concentration has the least effect among the interaction term. From the response optimization analysis the optimum time, pH, adsorbate concentration and adsorbent dose were found to be 300 min, 1.6, 400 mg/L and 2.4 g/L respectively. Multivariate analysis technique was used to find out the correlation among different adsorption parameters. The factorial analysis showed that the response variable can be explained by five factors and they explain more than 86 % of total variance.","STATISTICAL DESIGN OF EXPERIMENTS FOR THE Cr(VI) ADSORPTION ON WEED Salvinia cucullata Abs: Experiments were designed to optimize the Cr(VI) adsorption on Salvinia cucullata. The significance of different adsorption parameters along with their combined effect on the adsorption process has been established. A regression equation was formulated by representing percentage of Cr(VI) adsorption as a function of different independent variables such as contact time, pH, adsorbate concentration and adsorbent dose. The insignificant terms were assessed through student 't' test and are removed from the regression equation. The resulting regression equation after removal of the insignificant terms was verified by using Fisher's adequacy test. The pH coefficient was the most dominant followed by adsorbate concentration and contact time. Adsorbent dose induces a small effect on adsorption process. Among the interaction term combined effect of contact time and adsorbate concentration has the most influential effect followed by combined effect of time, pH and adsorbate concentration. Combined effect of pH and adsorbate concentration has the least effect among the interaction term. From the response optimization analysis the optimum time, pH, adsorbate concentration and adsorbent dose were found to be 300 min, 1.6, 400 mg/L and 2.4 g/L respectively. Multivariate analysis technique was used to find out the correlation among different adsorption parameters. The factorial analysis showed that the response variable can be explained by five factors and they explain more than 86 % of total variance."
1786459,Amer et al. 2013,Oxidation of Benzylic Alcohols into Aldehydes Under Solvent-Free Microwave Irradiation Using New Catalyst-Support System,"This work deals with the catalytic conversion of alcohols to aldehydes using a new support-nanocatalyst system consisting of chromium trioxide supported on nanostructured hydroxyapatite (Cr-NHAP). The oxidation reaction was carried out on a series of substituted benzylic alcohols under solvent-free microwave irradiation conditions. The obtained results showed high selectivity and high yield that was found to depend on the nature, the electronegativity and the position (para or meta) of the substituent on the aromatic cycle of the reagent.","Oxidation of Benzylic Alcohols into Aldehydes Under Solvent-Free Microwave Irradiation Using New Catalyst-Support System Abs: This work deals with the catalytic conversion of alcohols to aldehydes using a new support-nanocatalyst system consisting of chromium trioxide supported on nanostructured hydroxyapatite (Cr-NHAP). The oxidation reaction was carried out on a series of substituted benzylic alcohols under solvent-free microwave irradiation conditions. The obtained results showed high selectivity and high yield that was found to depend on the nature, the electronegativity and the position (para or meta) of the substituent on the aromatic cycle of the reagent."
1786458,Al-Sou'Od 2013,Adsorption Kinetics for the Removal of Hexavalent Chromium using Low Cost Materials,"This study proposes Jordanian Pottery as a low cost adsorbent for the removal of chromium from aqueous solution. The effect of contact time, initial concentration of Cr(VI), temperature and ionic strength on the adsorption of Cr(VI) onto clay's pottery were studied and discussed. Four kinetic models, the pseudo first and second-order equations, the Elovich equation and the Ritchie's equation were selected to follow the adsorption process. The mechanism of sorption was investigated by using the intraparticle diffusion model. Kinetic parameters rate constants, equilibrium adsorption capacities and correlation coefficients, for each kinetic equation were calculated and discussed. Activation energy values were found to be between 13.85 and 33.10kJ mol(-1).","Adsorption Kinetics for the Removal of Hexavalent Chromium using Low Cost Materials Abs: This study proposes Jordanian Pottery as a low cost adsorbent for the removal of chromium from aqueous solution. The effect of contact time, initial concentration of Cr(VI), temperature and ionic strength on the adsorption of Cr(VI) onto clay's pottery were studied and discussed. Four kinetic models, the pseudo first and second-order equations, the Elovich equation and the Ritchie's equation were selected to follow the adsorption process. The mechanism of sorption was investigated by using the intraparticle diffusion model. Kinetic parameters rate constants, equilibrium adsorption capacities and correlation coefficients, for each kinetic equation were calculated and discussed. Activation energy values were found to be between 13.85 and 33.10kJ mol(-1)."
1786457,I??k et al. 2013,Development of a new chromium reducing antioxidant capacity (CHROMAC) assay for plants and fruits,"A chromium reducing antioxidant capacity (CHROMAC) assay was presented to measure antioxidant capacity of selected plants and fruits and compared its performance with other commonly used antioxidant capacity methods of 2,2'-azinobis(3-ethylbenzothiazoline-6-sulfonic acid) (ABTS) and cupric reducing antioxidant capacity (CUPRAC). The assay is based on the spectrophotometric measurement of colored a chelate complex of Cr(III) and diphenylcarbazone formed by the reaction of Cr(VI) and 1,5-diphenylcarbazid in acidic medium. Phenolic compounds react with excessive amounts of Cr(VI) at low pH values, causing reduction of Cr(VI) to Cr(III) and conversion of phenols to oxidized products. The assay comprises of the antioxidant with a chromium(VI) solution, a 1,5-diphenylcarbazid in acidic medium and subsequent measurement of the developed absorbance at 540 nm after 50 min. The color development is stable for phenolic compounds in plant and fruit. The selectivity of the assay for phenolic compounds was improved by adjusting pH to 2.8 and reduction potential between 0.2 and 0.9 V. The developed assay was successfully applied to the measurement of antioxidant capacity of three plants and one fruit (Prunus divaricata Ledeb.subsp. divaricata) samples and comparable results were obtained by ABTS and CUPRAC assays.","Development of a new chromium reducing antioxidant capacity (CHROMAC) assay for plants and fruits Abs: A chromium reducing antioxidant capacity (CHROMAC) assay was presented to measure antioxidant capacity of selected plants and fruits and compared its performance with other commonly used antioxidant capacity methods of 2,2'-azinobis(3-ethylbenzothiazoline-6-sulfonic acid) (ABTS) and cupric reducing antioxidant capacity (CUPRAC). The assay is based on the spectrophotometric measurement of colored a chelate complex of Cr(III) and diphenylcarbazone formed by the reaction of Cr(VI) and 1,5-diphenylcarbazid in acidic medium. Phenolic compounds react with excessive amounts of Cr(VI) at low pH values, causing reduction of Cr(VI) to Cr(III) and conversion of phenols to oxidized products. The assay comprises of the antioxidant with a chromium(VI) solution, a 1,5-diphenylcarbazid in acidic medium and subsequent measurement of the developed absorbance at 540 nm after 50 min. The color development is stable for phenolic compounds in plant and fruit. The selectivity of the assay for phenolic compounds was improved by adjusting pH to 2.8 and reduction potential between 0.2 and 0.9 V. The developed assay was successfully applied to the measurement of antioxidant capacity of three plants and one fruit (Prunus divaricata Ledeb.subsp. divaricata) samples and comparable results were obtained by ABTS and CUPRAC assays."
1786456,Zuo and  Balasubramanian 2013,Evaluation of a novel chitosan polymer-based adsorbent for the removal of chromium (III) in aqueous solutions,"Novel poly(vinyl alcohol)/citric acid/chitosan (PVA/CA/CHT, PCC) beads were prepared as an adsorbent for the removal of trivalent chromium (Cr(3+)) in aqueous solutions. PCC beads with different mass ratios (I, II, III, IV, V, ad VI) between PVA/CA/CHT were evaluated for the removal of Cr(3+) ions to find an optimal stoichiometry of PCC beads, which indicated that the PCC bead (II) with the PVA/CA/CHT mass ratio of 1/5/1 showed the highest adsorption for Cr(3+) ions. The surface characteristics of PCC beads (II) were determined by scanning electron microscopy using a field emission scanning electron microscope (FESEM) and Fourier transform infrared spectroscopy (FTIR). The results obtained in this study implied that PCC bead (II) had an obviously rough and folded structure, and its spectrum manifested significant changes compared to those of PVA, CA and CHT. The sorption experiments were conducted to evaluate the performance of PCC beads (II) to adsorb Cr(3+) ions in aqueous solutions. Results indicated that the Cr(3+) ion sorption onto PCC beads (II) was highly pH-dependent with the maximum uptake at pH 6.0. The sorption kinetics data were well fitted by the pseudo-second-order equation with high regression coefficients. Sorption isotherm of PCC beads (II) was well described by Langmuir equation, with a maximum sorption at 41.5mg Cr/g PCC beads (II). Desorption studies were also carried out by the repeated sorption/desorption experiments. The high efficiency and reusability of PCC beads (II) make them an attractive sorbent for the removal of Cr(3+) and possibly other metals in aqueous solutions.","Evaluation of a novel chitosan polymer-based adsorbent for the removal of chromium (III) in aqueous solutions Abs: Novel poly(vinyl alcohol)/citric acid/chitosan (PVA/CA/CHT, PCC) beads were prepared as an adsorbent for the removal of trivalent chromium (Cr(3+)) in aqueous solutions. PCC beads with different mass ratios (I, II, III, IV, V, ad VI) between PVA/CA/CHT were evaluated for the removal of Cr(3+) ions to find an optimal stoichiometry of PCC beads, which indicated that the PCC bead (II) with the PVA/CA/CHT mass ratio of 1/5/1 showed the highest adsorption for Cr(3+) ions. The surface characteristics of PCC beads (II) were determined by scanning electron microscopy using a field emission scanning electron microscope (FESEM) and Fourier transform infrared spectroscopy (FTIR). The results obtained in this study implied that PCC bead (II) had an obviously rough and folded structure, and its spectrum manifested significant changes compared to those of PVA, CA and CHT. The sorption experiments were conducted to evaluate the performance of PCC beads (II) to adsorb Cr(3+) ions in aqueous solutions. Results indicated that the Cr(3+) ion sorption onto PCC beads (II) was highly pH-dependent with the maximum uptake at pH 6.0. The sorption kinetics data were well fitted by the pseudo-second-order equation with high regression coefficients. Sorption isotherm of PCC beads (II) was well described by Langmuir equation, with a maximum sorption at 41.5mg Cr/g PCC beads (II). Desorption studies were also carried out by the repeated sorption/desorption experiments. The high efficiency and reusability of PCC beads (II) make them an attractive sorbent for the removal of Cr(3+) and possibly other metals in aqueous solutions."
1786455,Zou et al. 2013,A competitive immunoassay based on gold nanoparticles for the detection of chromium in water samples,,A competitive immunoassay based on gold nanoparticles for the detection of chromium in water samples Abs: 
1786454,Zhu et al. 2013,"Rapid removal of Cr(VI) ions from aqueous solutions by the macroporous poly( N, N ?-dimethylamino ethyl methacrylate) hydrogels",,"Rapid removal of Cr(VI) ions from aqueous solutions by the macroporous poly( N, N ?-dimethylamino ethyl methacrylate) hydrogels Abs: "
1786453,Zhou et al. 2013,Enhanced sorption of perfluorooctane sulfonate and Cr(VI) on organo montmorillonite: influence of solution pH and uptake mechanism,,Enhanced sorption of perfluorooctane sulfonate and Cr(VI) on organo montmorillonite: influence of solution pH and uptake mechanism Abs: 
1786452,Zhou et al. 2013,Enhanced bioremediation of heavy metal from effluent by sulfate-reducing bacteria with copper-iron bimetallic particles support,"The purpose of this study was to investigate the potential of copper-iron bimetallic particles supported sulfate-reducing bacteria (SRB) in enhancing the reduction of Cu(2+) and Zn(2+) in effluent. The results showed that the copper-iron bimetallic particles can enhance Cu(2+) and Zn(2+) removal and the resistance of the sulfate-reducing bacteria towards metals toxicity, the inhibiting concentration of Cu(2+) and Zn(2+) for SRB was significantly increased (from 100 to 200 mg/L for Cu(2+) and 300 to 400 mg/L for Zn(2+)). The removal efficiencies of Cu(2+) and Zn(2+) (initial concentration 100 mg/L) were 98.17% and 99.67% in SRB-Cu/Fe system after 48 h, while only 29.83% Cu(2+), 90.88% Zn(2+) and 63.81% Cu(2+), 72.63% Zn(2+) were removed in the SRB and Cu/Fe system at the same condition.","Enhanced bioremediation of heavy metal from effluent by sulfate-reducing bacteria with copper-iron bimetallic particles support Abs: The purpose of this study was to investigate the potential of copper-iron bimetallic particles supported sulfate-reducing bacteria (SRB) in enhancing the reduction of Cu(2+) and Zn(2+) in effluent. The results showed that the copper-iron bimetallic particles can enhance Cu(2+) and Zn(2+) removal and the resistance of the sulfate-reducing bacteria towards metals toxicity, the inhibiting concentration of Cu(2+) and Zn(2+) for SRB was significantly increased (from 100 to 200 mg/L for Cu(2+) and 300 to 400 mg/L for Zn(2+)). The removal efficiencies of Cu(2+) and Zn(2+) (initial concentration 100 mg/L) were 98.17% and 99.67% in SRB-Cu/Fe system after 48 h, while only 29.83% Cu(2+), 90.88% Zn(2+) and 63.81% Cu(2+), 72.63% Zn(2+) were removed in the SRB and Cu/Fe system at the same condition."
1786451,Zhao et al. 2013,Effective adsorption of Cr (VI) from aqueous solution using natural Akadama clay,"In this study, natural Akadama clay was used for Cr (VI) removal from aqueous solution. Batch experiments were carried out to investigate the effect of contact time, initial pH, and adsorbent dose on Cr (VI) adsorption. Results showed that Cr (VI) adsorption on natural Akadama clay reached equilibrium in 180 min. The Cr (VI) removal efficiency of 46.8% without pH adjustment increased to 73.8% at the optimum initial pH of 2. The maximum adsorption capacity was 4.29 mg g(-1) at an initial concentration of 50.0 mg L(-1) and adsorbent dosage of 5 g L(-1). The equilibrium data fitted Freundlich isotherm better than Langmuir isotherm, and they were well explained by pseudo-second-order kinetic model. Adsorption mechanism analysis proved that electrostatic adsorption dominated during the removal process. Results from this study demonstrate that natural Akadama clay has the potential to be an efficient adsorbent for Cr (VI) adsorption compared to other natural mineral adsorbents.","Effective adsorption of Cr (VI) from aqueous solution using natural Akadama clay Abs: In this study, natural Akadama clay was used for Cr (VI) removal from aqueous solution. Batch experiments were carried out to investigate the effect of contact time, initial pH, and adsorbent dose on Cr (VI) adsorption. Results showed that Cr (VI) adsorption on natural Akadama clay reached equilibrium in 180 min. The Cr (VI) removal efficiency of 46.8% without pH adjustment increased to 73.8% at the optimum initial pH of 2. The maximum adsorption capacity was 4.29 mg g(-1) at an initial concentration of 50.0 mg L(-1) and adsorbent dosage of 5 g L(-1). The equilibrium data fitted Freundlich isotherm better than Langmuir isotherm, and they were well explained by pseudo-second-order kinetic model. Adsorption mechanism analysis proved that electrostatic adsorption dominated during the removal process. Results from this study demonstrate that natural Akadama clay has the potential to be an efficient adsorbent for Cr (VI) adsorption compared to other natural mineral adsorbents."
1786450,Zhao and  Wang 2013,Adhesion improvement of electroless copper to ABS resin by low environmental pollution surface etching system,,Adhesion improvement of electroless copper to ABS resin by low environmental pollution surface etching system Abs: 
1786449,Zhang et al. 2013,Characterization of film properties on the NiCrMo Alloy C-2000,,Characterization of film properties on the NiCrMo Alloy C-2000 Abs: 
1786448,Zhang et al. 2013,Remediation of an electroplating contaminated soil by EDTA flushing: chromium release and soil dissolution,,Remediation of an electroplating contaminated soil by EDTA flushing: chromium release and soil dissolution Abs: 
1786447,Zhang et al. 2013,A proof-of-concept fluorescent strategy for highly selective detection of Cr(vi) based on inner filter effect using a hydrophilic ionic chemosensor,,A proof-of-concept fluorescent strategy for highly selective detection of Cr(vi) based on inner filter effect using a hydrophilic ionic chemosensor Abs: 
1786446,Zafar et al. 2013,Trichoderma harzianum : a green sorbent for Pb(II) uptake from aqueous solutions,,Trichoderma harzianum : a green sorbent for Pb(II) uptake from aqueous solutions Abs: 
1786445,Yurlova et al. 2013,The use of cationogenic SAS in pressure-driven processes of purification of water contaminated with Cr (VI) salts,,The use of cationogenic SAS in pressure-driven processes of purification of water contaminated with Cr (VI) salts Abs: 
1786444,Yu et al. 2013,Copper ion adsorption by chitosan nanoparticles and alginate microparticles for water purification applications,,Copper ion adsorption by chitosan nanoparticles and alginate microparticles for water purification applications Abs: 
1786443,Yang et al. 2013,Coupling of tartaric acid-promoted soil dissolution and Cr(VI) reduction in an Oxisol,,Coupling of tartaric acid-promoted soil dissolution and Cr(VI) reduction in an Oxisol Abs: 
1786442,Yadav et al. 2013,"Adsorption characteristics of modified sand for the removal of hexavalent chromium ions from aqueous solutions: Kinetic, thermodynamic and equilibrium studies",,"Adsorption characteristics of modified sand for the removal of hexavalent chromium ions from aqueous solutions: Kinetic, thermodynamic and equilibrium studies Abs: "
1786441,Yadav and  Xu 2013,Catalytic chromium reduction using formic acid and metal nanoparticles immobilized in a metal-organic framework,"Highly dispersed metal nanoparticles were immobilized in the pores of a metal-organic framework (MOF), MIL-101, using a double solvents method. The resulting composites were investigated in the reduction of Cr(VI) to Cr(III) using formic acid, showing that the Pt and Pd catalysts were active with the Pt nanoparticles immobilized in MOF exhibiting the best performance.","Catalytic chromium reduction using formic acid and metal nanoparticles immobilized in a metal-organic framework Abs: Highly dispersed metal nanoparticles were immobilized in the pores of a metal-organic framework (MOF), MIL-101, using a double solvents method. The resulting composites were investigated in the reduction of Cr(VI) to Cr(III) using formic acid, showing that the Pt and Pd catalysts were active with the Pt nanoparticles immobilized in MOF exhibiting the best performance."
1786440,Zengguang et al. 2013,Optimization of a PRB structure with modified chitosan restoring Cr(VI)-contaminated groundwater,,Optimization of a PRB structure with modified chitosan restoring Cr(VI)-contaminated groundwater Abs: 
1786439,Xu et al. 2013,Structure-Enhanced Photocatalytic Removal of Cr VI by a TiO 2 Superstructure with Ultrathin Rutile Nanorods and Abundant {110} Faces,,Structure-Enhanced Photocatalytic Removal of Cr VI by a TiO 2 Superstructure with Ultrathin Rutile Nanorods and Abundant {110} Faces Abs: 
1786438,Xie et al. 2013,Comparative study of chromium biosorption by Mesorhizobium amorphae strain CCNWGS0123 in single and binary mixtures,"The appearance of chromium in the aqueous effluent is a major concern for the modern industry. In this work, Mesorhizobium amorphae strain CCNWGS0123 was investigated as a biosorbent to remove chromium from aqueous solutions. The optimum pH for Cr(III) and Cr(VI) biosorption were 4 and 2, respectively. This isolate showed an experimental maximum Cr(III) adsorption capacity of 53.52 mg?L(-1), while the result was 47.67 mg?L(-1) for Cr(VI), with an initial 100 mg?L(-1) Cr ions and 1.0 g?L(-1) biomass. In terms of time equilibrium, Cr(III) ion was more readily adsorbed than Cr(VI) by this isolate. The biosorption data of both ions fit the Langmuir isotherm better than that of Freundlich model. Meanwhile, this organism exhibited a good capability to release Cr ions, with desorption efficiency of 70 % for Cr(III) and 76 % for Cr(VI). Fourier transform infrared spectroscopy analysis showed that -OH, -COO, -NH, amide I, and C=O were involved in Cr(III) and Cr(VI) binding. The biosorbent was further characterized by scanning electron microscopy and energy-dispersive X-ray spectrometry, which indicated an accumulation of chromium on the cellular level. In the binary mixtures, the removal ratio of total Cr and Cr(III) increased from pH?2 to 4. The highest removal ratio of the total Cr was observed in the 25/25 mg?L(-1) mixture at pH?4. In addition, the removal efficiency of Cr(VI) was closely influenced by Cr(III) in the mixture, decreasing to 23.57 mg?g(-1) in the 100/100 mg?L(-1) mixture system, due to the competition of Cr(III). The potential usage of the chromium-resistant rhizobium for the remediation of chromium-contaminated effluents has been demonstrated based on the above results.","Comparative study of chromium biosorption by Mesorhizobium amorphae strain CCNWGS0123 in single and binary mixtures Abs: The appearance of chromium in the aqueous effluent is a major concern for the modern industry. In this work, Mesorhizobium amorphae strain CCNWGS0123 was investigated as a biosorbent to remove chromium from aqueous solutions. The optimum pH for Cr(III) and Cr(VI) biosorption were 4 and 2, respectively. This isolate showed an experimental maximum Cr(III) adsorption capacity of 53.52 mg?L(-1), while the result was 47.67 mg?L(-1) for Cr(VI), with an initial 100 mg?L(-1) Cr ions and 1.0 g?L(-1) biomass. In terms of time equilibrium, Cr(III) ion was more readily adsorbed than Cr(VI) by this isolate. The biosorption data of both ions fit the Langmuir isotherm better than that of Freundlich model. Meanwhile, this organism exhibited a good capability to release Cr ions, with desorption efficiency of 70 % for Cr(III) and 76 % for Cr(VI). Fourier transform infrared spectroscopy analysis showed that -OH, -COO, -NH, amide I, and C=O were involved in Cr(III) and Cr(VI) binding. The biosorbent was further characterized by scanning electron microscopy and energy-dispersive X-ray spectrometry, which indicated an accumulation of chromium on the cellular level. In the binary mixtures, the removal ratio of total Cr and Cr(III) increased from pH?2 to 4. The highest removal ratio of the total Cr was observed in the 25/25 mg?L(-1) mixture at pH?4. In addition, the removal efficiency of Cr(VI) was closely influenced by Cr(III) in the mixture, decreasing to 23.57 mg?g(-1) in the 100/100 mg?L(-1) mixture system, due to the competition of Cr(III). The potential usage of the chromium-resistant rhizobium for the remediation of chromium-contaminated effluents has been demonstrated based on the above results."
1786437,Xiao et al. 2013,Accumulation of chromium in pak choi ( L.) grown on representative chinese soils,"Anthropogenic chromium (Cr) pollution in soils poses a great threat to human health through the food chain. It is imperative to understand Cr accumulation properties in common vegetables because the proportion of vegetables consumed has increased with the improvement of living standards. This study investigated Cr accumulation in pak choi ( L.) grown on six representative agricultural soils in China. Chromium concentration in the edible parts of pak choi generally increased with soil Cr concentrations following the order: Ustic Cambosols &gt; Periudic Argosols &gt; Mollisols &gt; Calcaric Regosols &gt; Stagnic Anthrosols &gt; Udic Ferrisols. Simple correlation analysis indicated that Cr concentration in pak choi was significantly correlated with the total Cr, Mehlich-3-extractable Cr, and Cr(VI). Stepwise multiple regression analysis also demonstrated that the phytoavailability of Cr was strongly correlated with the extractable fraction by Mehlich-3, total Cr concentration, soil organic matter, and Fe(II). Critical Cr concentrations in these six soils were evaluated for pak choi based on the maximum safe level for daily intake of Cr. Total soil Cr can be used as Cr thresholds for potential dietary toxicity in pak choi. Mehlich-3-extractable Cr is most suitable to be used as Cr thresholds for Periudic Argosols, Udic Ferrisols, Mollisols, and Ustic Cambosols, with values of 20.7, 15.8, 21.2, and 20.4 mg kg, respectively, whereas Cr(VI) is most suitable for Calcaric Regosols and Stagnic Anthrosols, with values of 26.5 and 28.0 mg kg, respectively.","Accumulation of chromium in pak choi ( L.) grown on representative chinese soils Abs: Anthropogenic chromium (Cr) pollution in soils poses a great threat to human health through the food chain. It is imperative to understand Cr accumulation properties in common vegetables because the proportion of vegetables consumed has increased with the improvement of living standards. This study investigated Cr accumulation in pak choi ( L.) grown on six representative agricultural soils in China. Chromium concentration in the edible parts of pak choi generally increased with soil Cr concentrations following the order: Ustic Cambosols &gt; Periudic Argosols &gt; Mollisols &gt; Calcaric Regosols &gt; Stagnic Anthrosols &gt; Udic Ferrisols. Simple correlation analysis indicated that Cr concentration in pak choi was significantly correlated with the total Cr, Mehlich-3-extractable Cr, and Cr(VI). Stepwise multiple regression analysis also demonstrated that the phytoavailability of Cr was strongly correlated with the extractable fraction by Mehlich-3, total Cr concentration, soil organic matter, and Fe(II). Critical Cr concentrations in these six soils were evaluated for pak choi based on the maximum safe level for daily intake of Cr. Total soil Cr can be used as Cr thresholds for potential dietary toxicity in pak choi. Mehlich-3-extractable Cr is most suitable to be used as Cr thresholds for Periudic Argosols, Udic Ferrisols, Mollisols, and Ustic Cambosols, with values of 20.7, 15.8, 21.2, and 20.4 mg kg, respectively, whereas Cr(VI) is most suitable for Calcaric Regosols and Stagnic Anthrosols, with values of 26.5 and 28.0 mg kg, respectively."
1786436,Xiao et al. 2013,Model for evaluation of the phytoavailability of chromium (Cr) to rice (Oryza sativa L.) in representative Chinese soils,"Anthropogenic chromium (Cr) pollution in soils poses a great threat to human health through the food chain. It is imperative to understand Cr phytoavailability to rice (Oryza sativa L.), which is a major staple food crop for the largest population of people on Earth. This study was aimed to establish a model for evaluation of the phytoavailability of Cr to rice in six representative Chinese soils based on soil properties. Simple correlation analysis indicated that Cr concentration in polished rice was significantly correlated with total Cr, Mehlich-3 extractable Cr, and Cr(VI) in soil. Stepwise multiple regression analysis also demonstrated that the Cr phytoavailability was strongly correlated with soil total Cr, Mehlich-3 extractable Cr, Cr(VI) concentration, soil organic matter, Fe(II), and particle size distribution. Critical Cr concentrations in the six soils were evaluated for rice based on the maximum safe level for daily intake of Cr. Mehlich-3 extractable Cr are the most suitable Cr thresholds for Periudic Argosols, Udic Ferrisols, Mollisols, and Ustic Cambosols with values of 1.54, 0.56, 0.42, and 2.18 mg kg(-1), respectively, while Cr(VI) are adequate thresholds for Calcaric Regosols and Stagnic Anthrosols with values of 0.68 and 0.84 mg kg(-1), respectively.","Model for evaluation of the phytoavailability of chromium (Cr) to rice (Oryza sativa L.) in representative Chinese soils Abs: Anthropogenic chromium (Cr) pollution in soils poses a great threat to human health through the food chain. It is imperative to understand Cr phytoavailability to rice (Oryza sativa L.), which is a major staple food crop for the largest population of people on Earth. This study was aimed to establish a model for evaluation of the phytoavailability of Cr to rice in six representative Chinese soils based on soil properties. Simple correlation analysis indicated that Cr concentration in polished rice was significantly correlated with total Cr, Mehlich-3 extractable Cr, and Cr(VI) in soil. Stepwise multiple regression analysis also demonstrated that the Cr phytoavailability was strongly correlated with soil total Cr, Mehlich-3 extractable Cr, Cr(VI) concentration, soil organic matter, Fe(II), and particle size distribution. Critical Cr concentrations in the six soils were evaluated for rice based on the maximum safe level for daily intake of Cr. Mehlich-3 extractable Cr are the most suitable Cr thresholds for Periudic Argosols, Udic Ferrisols, Mollisols, and Ustic Cambosols with values of 1.54, 0.56, 0.42, and 2.18 mg kg(-1), respectively, while Cr(VI) are adequate thresholds for Calcaric Regosols and Stagnic Anthrosols with values of 0.68 and 0.84 mg kg(-1), respectively."
1786435,Wu et al. 2012,Colorimetric determination of hexavalent chromium with ascorbic acid capped silver nanoparticles,,Colorimetric determination of hexavalent chromium with ascorbic acid capped silver nanoparticles Abs: 
1786434,Wen et al. 2013,Room temperature ionic liquid-based dispersive liquid–liquid microextraction combined with flame atomic absorption spectrometry for the speciation of chromium(III) and chromium(VI),,Room temperature ionic liquid-based dispersive liquid–liquid microextraction combined with flame atomic absorption spectrometry for the speciation of chromium(III) and chromium(VI) Abs: 
1786433,Weiss et al. 2013,Levels and predictors of airborne and internal exposure to chromium and nickel among welders--results of the WELDOX study,"The objective of this analysis was to investigate levels and determinants of exposure to airborne and urinary chromium (Cr, CrU) and nickel (Ni, NiU) among 241 welders. Respirable and inhalable welding fume was collected during a shift, and the metal content was determined using inductively coupled plasma mass spectrometry. In post-shift urine, CrU and NiU were measured by means of graphite furnace atom absorption spectrometry, with resulting concentrations varying across a wide range. Due to a large fraction below the limits of quantitation we applied multiple imputations to the log-transformed exposure variables for the analysis of the data. Respirable Cr and Ni were about half of the concentrations of inhalable Cr and Ni, respectively. CrU and NiU were determined with medians of 1.2 ?g/L (interquartile range &lt;1.00; 3.61) and 2.9 ?g/L (interquartile range &lt;1.50; 5.97). Furthermore, Cr and Ni correlated in respirable welding fume (r=0.79, 95% CI 0.74-0.85) and urine (r=0.55, 95% CI 0.44-0.65). Regression models identified exposure-modulating variables in form of multiplicative factors and revealed slightly better model fits for Cr (R(2) respirable Cr 48%, CrU 55%) than for Ni (R(2) respirable Ni 42%, NiU 38%). The air concentrations were mainly predicted by the metal content in electrodes or base material in addition to the welding technique. Respirable Cr and Ni were good predictors for CrU and NiU, respectively. Exposure was higher when welding was performed in confined spaces or with inefficient ventilation, and lower in urine when respirators were used. In conclusion, statistical modelling allowed the evaluation of determinants of internal and external exposure to Cr and Ni in welders. Welding parameters were stronger predictors than workplace conditions. Airborne exposure was lowest inside respirators with supply of purified air.","Levels and predictors of airborne and internal exposure to chromium and nickel among welders--results of the WELDOX study Abs: The objective of this analysis was to investigate levels and determinants of exposure to airborne and urinary chromium (Cr, CrU) and nickel (Ni, NiU) among 241 welders. Respirable and inhalable welding fume was collected during a shift, and the metal content was determined using inductively coupled plasma mass spectrometry. In post-shift urine, CrU and NiU were measured by means of graphite furnace atom absorption spectrometry, with resulting concentrations varying across a wide range. Due to a large fraction below the limits of quantitation we applied multiple imputations to the log-transformed exposure variables for the analysis of the data. Respirable Cr and Ni were about half of the concentrations of inhalable Cr and Ni, respectively. CrU and NiU were determined with medians of 1.2 ?g/L (interquartile range &lt;1.00; 3.61) and 2.9 ?g/L (interquartile range &lt;1.50; 5.97). Furthermore, Cr and Ni correlated in respirable welding fume (r=0.79, 95% CI 0.74-0.85) and urine (r=0.55, 95% CI 0.44-0.65). Regression models identified exposure-modulating variables in form of multiplicative factors and revealed slightly better model fits for Cr (R(2) respirable Cr 48%, CrU 55%) than for Ni (R(2) respirable Ni 42%, NiU 38%). The air concentrations were mainly predicted by the metal content in electrodes or base material in addition to the welding technique. Respirable Cr and Ni were good predictors for CrU and NiU, respectively. Exposure was higher when welding was performed in confined spaces or with inefficient ventilation, and lower in urine when respirators were used. In conclusion, statistical modelling allowed the evaluation of determinants of internal and external exposure to Cr and Ni in welders. Welding parameters were stronger predictors than workplace conditions. Airborne exposure was lowest inside respirators with supply of purified air."
1786432,Wei et al. 2013,High-capacity adsorption of Cr(VI) from aqueous solution using a hierarchical porous carbon obtained from pig bone,"A hierarchical porous carbon obtained from pig bone (HPC) was utilized as the adsorbent for removal of Cr(VI) from aqueous solution. The effects of solution pH value, concentration of Cr(VI), and adsorption temperature on the removal of Cr(VI) were investigated. The experimental data of the HPC fitted well with the Langmuir isotherm and its adsorption kinetic followed pseudo-second order model. Compared with a commercial activated carbon adsorbent (Norit CGP), the HPC showed an high adsorption capability for Cr(VI). The maximum Cr(VI) adsorption capacity of the HPC was 398.40 mg/g at pH 2. It is found that a part of the Cr(VI) was reduced to Cr(III) on the adsorbent surface from desorption experiment data. The regeneration showed adsorption capacity of the HPC can still achieve 92.70 mg/g even after fifth adsorption cycle.","High-capacity adsorption of Cr(VI) from aqueous solution using a hierarchical porous carbon obtained from pig bone Abs: A hierarchical porous carbon obtained from pig bone (HPC) was utilized as the adsorbent for removal of Cr(VI) from aqueous solution. The effects of solution pH value, concentration of Cr(VI), and adsorption temperature on the removal of Cr(VI) were investigated. The experimental data of the HPC fitted well with the Langmuir isotherm and its adsorption kinetic followed pseudo-second order model. Compared with a commercial activated carbon adsorbent (Norit CGP), the HPC showed an high adsorption capability for Cr(VI). The maximum Cr(VI) adsorption capacity of the HPC was 398.40 mg/g at pH 2. It is found that a part of the Cr(VI) was reduced to Cr(III) on the adsorbent surface from desorption experiment data. The regeneration showed adsorption capacity of the HPC can still achieve 92.70 mg/g even after fifth adsorption cycle."
1786431,Wanner and  Sonnenthal 2013,Assessing the control on the effective kinetic Cr isotope fractionation factor: A reactive transport modeling approach,,Assessing the control on the effective kinetic Cr isotope fractionation factor: A reactive transport modeling approach Abs: 
1786430,Wang et al. 2013,Uraninite oxidation and dissolution induced by manganese oxide: A redox reaction between two insoluble minerals,,Uraninite oxidation and dissolution induced by manganese oxide: A redox reaction between two insoluble minerals Abs: 
1786429,Wang et al. 2013,Single-cell imaging and spectroscopic analyses of Cr(VI) reduction on the surface of bacterial cells,"We investigate the single-cell reduction of toxic Cr(VI) by the dissimilatory metal-reducing bacterium Shewanella oneidensis MR-1 (MR-1), an important bioremediation process, using Raman spectroscopy and scanning electron microscopy (SEM) combined with energy-dispersive X-ray spectroscopy (EDX). Our experiments indicate that the toxic, highly soluble Cr(VI) can be efficiently reduced to less toxic, nonsoluble Cr(2)O(3) nanoparticles by MR-1. Cr(2)O(3) is observed to emerge as nanoparticles adsorbed on the cell surface and its chemical nature is identified by EDX imaging and Raman spectroscopy. Co-localization of Cr(2)O(3) and cytochromes by EDX imaging and Raman spectroscopy suggests a terminal reductase role for MR-1 surface-exposed cytochromes MtrC and OmcA. Our experiments revealed that the cooperation of surface proteins OmcA and MtrC makes the reduction reaction most efficient, and the sequence of the reducing reactivity of MR-1 is wild type &gt; single mutant ?mtrC or mutant ?omcA &gt; double mutant (?omcA-?mtrC). Moreover, our results also suggest that direct microbial Cr(VI) reduction and Fe(II) (hematite)-mediated Cr(VI) reduction mechanisms may coexist in the reduction processes.","Single-cell imaging and spectroscopic analyses of Cr(VI) reduction on the surface of bacterial cells Abs: We investigate the single-cell reduction of toxic Cr(VI) by the dissimilatory metal-reducing bacterium Shewanella oneidensis MR-1 (MR-1), an important bioremediation process, using Raman spectroscopy and scanning electron microscopy (SEM) combined with energy-dispersive X-ray spectroscopy (EDX). Our experiments indicate that the toxic, highly soluble Cr(VI) can be efficiently reduced to less toxic, nonsoluble Cr(2)O(3) nanoparticles by MR-1. Cr(2)O(3) is observed to emerge as nanoparticles adsorbed on the cell surface and its chemical nature is identified by EDX imaging and Raman spectroscopy. Co-localization of Cr(2)O(3) and cytochromes by EDX imaging and Raman spectroscopy suggests a terminal reductase role for MR-1 surface-exposed cytochromes MtrC and OmcA. Our experiments revealed that the cooperation of surface proteins OmcA and MtrC makes the reduction reaction most efficient, and the sequence of the reducing reactivity of MR-1 is wild type &gt; single mutant ?mtrC or mutant ?omcA &gt; double mutant (?omcA-?mtrC). Moreover, our results also suggest that direct microbial Cr(VI) reduction and Fe(II) (hematite)-mediated Cr(VI) reduction mechanisms may coexist in the reduction processes."
1786428,Wang et al. 2013,Individual and competitive adsorption of Cr(VI) and phosphate onto synthetic Fe–Al hydroxides,,Individual and competitive adsorption of Cr(VI) and phosphate onto synthetic Fe–Al hydroxides Abs: 
1786427,Wang et al. 2013,"Modification of Pd-Fe nanoparticles for catalytic dechlorination of 2,4-dichlorophenol","To reveal how different dispersants influence the dispersity and physicochemical properties of palladium/iron nanoparticles (Pd/Fe NPs), we modified Pd/Fe NPs with poly(methylmethacrylate) (PMMA), polyacrylic acid (PAA) and cetyltrimethylammonium bromide (CTAB) respectively and obtained three hybrid NPs denoted M-Pd/Fe NPs, A-Pd/Fe NPs and C-Pd/Fe NPs. The physical properties of the three hybrid Pd/Fe NPs were studied, together with their behaviors in the room-temperature dechlorination in aqueous solution of 2,4-dichlorophenol (2,4-DCP). Dispersant effects of the three dispersants were observed, as well as changes in the properties of resulted Pd/Fe NPs. The pristine Pd/Fe NPs experienced more severe oxidation than A-Pd/Fe NPs, while there was no evidence for the presence of oxidation phase of M-Pd/Fe NPs and C-Pd/Fe NPs. Degradation results showed that compared with pristine Pd/Fe NPs, the catalytic dechlorination efficiency of 2,4-DCP with modified Pd/Fe NPs increased by 23%-58% within a given reaction period of 20 min. The role of dispersants themselves in dechlorination properties of Pd/Fe NPs is more significant than that of volume ratio of PAA to water, weight ratio of PMMA to anisole and volume ratio of water to ethanol in determining the properties of A-Pd/Fe, M-Pd/Fe and C-Pd/Fe NPs, respectively. Studies on the kinetics of 2,4-DCP reacted with Pd/Fe NPs in our cases implied that their behaviors didn't match the first- or pseudo-first-order kinetics: because the presence of oxidation phases on the surface of pristine Pd/Fe NPs and the dispersants on the surface of NPs could influence the diffusion of 2,4-DCP onto reactive sites, thus affecting the whole degradation process. So, an innovatively revised kinetics was proposed in the study for considering the effects of oxidation phases and the dispersants.","Modification of Pd-Fe nanoparticles for catalytic dechlorination of 2,4-dichlorophenol Abs: To reveal how different dispersants influence the dispersity and physicochemical properties of palladium/iron nanoparticles (Pd/Fe NPs), we modified Pd/Fe NPs with poly(methylmethacrylate) (PMMA), polyacrylic acid (PAA) and cetyltrimethylammonium bromide (CTAB) respectively and obtained three hybrid NPs denoted M-Pd/Fe NPs, A-Pd/Fe NPs and C-Pd/Fe NPs. The physical properties of the three hybrid Pd/Fe NPs were studied, together with their behaviors in the room-temperature dechlorination in aqueous solution of 2,4-dichlorophenol (2,4-DCP). Dispersant effects of the three dispersants were observed, as well as changes in the properties of resulted Pd/Fe NPs. The pristine Pd/Fe NPs experienced more severe oxidation than A-Pd/Fe NPs, while there was no evidence for the presence of oxidation phase of M-Pd/Fe NPs and C-Pd/Fe NPs. Degradation results showed that compared with pristine Pd/Fe NPs, the catalytic dechlorination efficiency of 2,4-DCP with modified Pd/Fe NPs increased by 23%-58% within a given reaction period of 20 min. The role of dispersants themselves in dechlorination properties of Pd/Fe NPs is more significant than that of volume ratio of PAA to water, weight ratio of PMMA to anisole and volume ratio of water to ethanol in determining the properties of A-Pd/Fe, M-Pd/Fe and C-Pd/Fe NPs, respectively. Studies on the kinetics of 2,4-DCP reacted with Pd/Fe NPs in our cases implied that their behaviors didn't match the first- or pseudo-first-order kinetics: because the presence of oxidation phases on the surface of pristine Pd/Fe NPs and the dispersants on the surface of NPs could influence the diffusion of 2,4-DCP onto reactive sites, thus affecting the whole degradation process. So, an innovatively revised kinetics was proposed in the study for considering the effects of oxidation phases and the dispersants."
1786426,Wang et al. 2013,Simultaneous analysis of photosystem responses of Microcystis aeruginoga under chromium stress,"Chromium (Cr) is a toxic metal that poses a great threat to aquatic ecosystems. Information is limited on coinstantaneous responses of photosystems I (PSI) and II (PSII) to Cr(VI) stress due to lack of instruments that can simultaneously measure PSI and PSII activities. In the present study, responses of quantum yields of energy conversion and electron transport rates of PSI and PSII in Microcystis aeruginosa cells to Cr(VI) stress were simultaneously analyzed by a DUAL-PAM-100 system. Quantum yield of cyclic electron flow (CEF) under Cr(VI) stress and its physiological role in alleviating toxicity of Cr(VI) were also analyzed. At 5 mg L(-1) Cr(VI), quantum yield and electron transport rate of PSII decreased significantly, and light-induced non-photochemical fluorescence quenching lost. Cr(VI) also inhibited efficiency of PSII to use energy under high light more than of PSI. PSII showed lower maximal electron transport rate and light adaptability than PSI. Electron transport rate of PSI was higher and decreased less than that of PSII, implying less sensitivity of PSI to high light and Cr(VI). Energy dissipation through non-light-induced non-photochemical fluorescence quenching increased with increasing Cr(VI) concentration. CEF was stimulated under Cr(VI) treatment and made a significant contribution to quantum yield and electron transport of PSI, which was essential for protection of PSI from stresses of Cr(VI) and high light.","Simultaneous analysis of photosystem responses of Microcystis aeruginoga under chromium stress Abs: Chromium (Cr) is a toxic metal that poses a great threat to aquatic ecosystems. Information is limited on coinstantaneous responses of photosystems I (PSI) and II (PSII) to Cr(VI) stress due to lack of instruments that can simultaneously measure PSI and PSII activities. In the present study, responses of quantum yields of energy conversion and electron transport rates of PSI and PSII in Microcystis aeruginosa cells to Cr(VI) stress were simultaneously analyzed by a DUAL-PAM-100 system. Quantum yield of cyclic electron flow (CEF) under Cr(VI) stress and its physiological role in alleviating toxicity of Cr(VI) were also analyzed. At 5 mg L(-1) Cr(VI), quantum yield and electron transport rate of PSII decreased significantly, and light-induced non-photochemical fluorescence quenching lost. Cr(VI) also inhibited efficiency of PSII to use energy under high light more than of PSI. PSII showed lower maximal electron transport rate and light adaptability than PSI. Electron transport rate of PSI was higher and decreased less than that of PSII, implying less sensitivity of PSI to high light and Cr(VI). Energy dissipation through non-light-induced non-photochemical fluorescence quenching increased with increasing Cr(VI) concentration. CEF was stimulated under Cr(VI) treatment and made a significant contribution to quantum yield and electron transport of PSI, which was essential for protection of PSI from stresses of Cr(VI) and high light."
1786425,Wang et al. 2013,Short-term chromium-stress-induced alterations in the maize leaf proteome,"Soil contamination by chromium (Cr) has become an increasing problem worldwide as a result of extensive industrial activities. Chromium, especially hexavalent Cr, impairs the growth and productivity of plants. Although it has been proposed that plants could modify their metabolism to adapt to Cr stress by reprogramming the expression of genes, especially those related to the antioxidant system, damage response, and electron transport chain, evidence at the protein expression level is lacking. To better understand the precise mechanisms underlying Cr phytoxicity and the plant response to Cr exposure, the time-course of changes in the protein expression profile induced by short-term hexavalent Cr exposure (1, 6 and 24 h) were analyzed in maize leaves. Among the over 1200 protein spots detected reproducibly by two-dimensional electrophoresis (2-DE), 60 were found to be differentially accumulated during Cr stress treatment. Of the Cr-regulated proteins, 58 were identified using tandem mass spectrometry (MS/MS). The Cr-regulated proteins identified were mainly involved in ROS detoxification and defense responses (26%), photosynthesis and chloroplast organization (22%), post-transcriptional processing of mRNA and rRNA (12%), protein synthesis and folding (10%), the DNA damage response (5%), and the cytoskeleton (3%). The possible involvement of these Cr stress-responsive proteins in Cr phytoxicity and the plant response to Cr exposure in maize is discussed, taking into consideration the information available from other plant models. Our results provide preliminary evidence that will facilitate understanding the molecular mechanisms underlying Cr toxicity in maize.","Short-term chromium-stress-induced alterations in the maize leaf proteome Abs: Soil contamination by chromium (Cr) has become an increasing problem worldwide as a result of extensive industrial activities. Chromium, especially hexavalent Cr, impairs the growth and productivity of plants. Although it has been proposed that plants could modify their metabolism to adapt to Cr stress by reprogramming the expression of genes, especially those related to the antioxidant system, damage response, and electron transport chain, evidence at the protein expression level is lacking. To better understand the precise mechanisms underlying Cr phytoxicity and the plant response to Cr exposure, the time-course of changes in the protein expression profile induced by short-term hexavalent Cr exposure (1, 6 and 24 h) were analyzed in maize leaves. Among the over 1200 protein spots detected reproducibly by two-dimensional electrophoresis (2-DE), 60 were found to be differentially accumulated during Cr stress treatment. Of the Cr-regulated proteins, 58 were identified using tandem mass spectrometry (MS/MS). The Cr-regulated proteins identified were mainly involved in ROS detoxification and defense responses (26%), photosynthesis and chloroplast organization (22%), post-transcriptional processing of mRNA and rRNA (12%), protein synthesis and folding (10%), the DNA damage response (5%), and the cytoskeleton (3%). The possible involvement of these Cr stress-responsive proteins in Cr phytoxicity and the plant response to Cr exposure in maize is discussed, taking into consideration the information available from other plant models. Our results provide preliminary evidence that will facilitate understanding the molecular mechanisms underlying Cr toxicity in maize."
1786424,Vu?kovi? et al. 2013,Moss biomonitoring of air pollution with chromium in Croatia,"The purpose of this study was to determine the atmospheric deposition of chromium in Croatia by using moss biomonitoring technique and atomic emission spectrometry with inductively coupled plasma (ICP-AES). Moss samples (Hylocomium splendens, Hypnum cupressiforme, Brachythecium rutabulum and Homalothecium Sericeum) were collected from 121 sampling sites evenly distributed over the country, during the summer and autumn of 2010. Collected samples were air dried, then cleaned and digested by using microwave digestion system. The median value obtained in this study (1.94 mg kg?¹) compared with the median value of previous investigation performed in 2006 (2.75 mg kg?¹) shows that the content of chromium decreased. Higher contents of chromium were found in moss samples collected in the regions of Central Croatia, in/near the cities of Zagreb, Sisak and Kutina, which, in the most of the cases, are result of anthropogenic activities. In Costal Croatia, higher values have a natural origin due to the significantly higher content of Cr in soil from this region. The results were compared with those from similar studies in neighboring and other Balkan countries. It was established that the content of chromium in Croatia is lower than in the most of these countries.","Moss biomonitoring of air pollution with chromium in Croatia Abs: The purpose of this study was to determine the atmospheric deposition of chromium in Croatia by using moss biomonitoring technique and atomic emission spectrometry with inductively coupled plasma (ICP-AES). Moss samples (Hylocomium splendens, Hypnum cupressiforme, Brachythecium rutabulum and Homalothecium Sericeum) were collected from 121 sampling sites evenly distributed over the country, during the summer and autumn of 2010. Collected samples were air dried, then cleaned and digested by using microwave digestion system. The median value obtained in this study (1.94 mg kg?¹) compared with the median value of previous investigation performed in 2006 (2.75 mg kg?¹) shows that the content of chromium decreased. Higher contents of chromium were found in moss samples collected in the regions of Central Croatia, in/near the cities of Zagreb, Sisak and Kutina, which, in the most of the cases, are result of anthropogenic activities. In Costal Croatia, higher values have a natural origin due to the significantly higher content of Cr in soil from this region. The results were compared with those from similar studies in neighboring and other Balkan countries. It was established that the content of chromium in Croatia is lower than in the most of these countries."
1786423,Varga et al. 2013,Comparative study of sorption kinetics and equilibrium of chromium (VI) on charcoals prepared from different low-cost materials,,Comparative study of sorption kinetics and equilibrium of chromium (VI) on charcoals prepared from different low-cost materials Abs: 
1786422,Vaidyanathan et al. 2013,"Importance of ligand structure in DNA/protein binding, mutagenicity, excision repair and nutritional aspects of chromium(III) complexes","Chromium is extensively used in leather, chrome plating and refining industries. On one hand the occupational exposure to chromium leads to cancer, whereas on the contrary certain Cr(III) compounds have been proposed as nutritional supplements for Type II diabetes and as muscle building agents. Despite the positive outlook of chromium as a bio-essential element, there is increasing concern over the therapeutic application of Cr(III) based supplements, its bioavailability and toxicity profile. In this perspective, we discuss the role of ligand structure in mediating the interaction of chromium(III) complexes with DNA/protein, their mutagenic outcomes, adduct reparability and as nutritional supplements.","Importance of ligand structure in DNA/protein binding, mutagenicity, excision repair and nutritional aspects of chromium(III) complexes Abs: Chromium is extensively used in leather, chrome plating and refining industries. On one hand the occupational exposure to chromium leads to cancer, whereas on the contrary certain Cr(III) compounds have been proposed as nutritional supplements for Type II diabetes and as muscle building agents. Despite the positive outlook of chromium as a bio-essential element, there is increasing concern over the therapeutic application of Cr(III) based supplements, its bioavailability and toxicity profile. In this perspective, we discuss the role of ligand structure in mediating the interaction of chromium(III) complexes with DNA/protein, their mutagenic outcomes, adduct reparability and as nutritional supplements."
1786421,Troiano et al. 2013,Interaction of Cr(III) and Cr(VI) with Hematite Studied by Second Harmonic Generation,,Interaction of Cr(III) and Cr(VI) with Hematite Studied by Second Harmonic Generation Abs: 
1786420,Tripathi and  Garg 2013,"Co-remediation of pentachlorophenol and Cr6+ by free and immobilized cells of native Bacillus cereus isolate: Spectrometric characterization of PCP dechlorination products, bioreactor trial and chromate reductase activity",,"Co-remediation of pentachlorophenol and Cr6+ by free and immobilized cells of native Bacillus cereus isolate: Spectrometric characterization of PCP dechlorination products, bioreactor trial and chromate reductase activity Abs: "
1786419,Tang and  Lo 2013,Magnetic nanoparticles: essential factors for sustainable environmental applications,"In recent years, there has been an increasing use of engineered magnetic nanoparticles for remediation and water treatments, leading to elevated public concerns. To this end, it is necessary to enhance the understanding of how these magnetic nanoparticles react with contaminants and interact with the surrounding environment during applications. This review aims to provide a holistic overview of current knowledge of magnetic nanoparticles in environmental applications, emphasizing studies of zero-valent iron (nZVI), magnetite (Fe3O4) and maghemite (?-Fe2O3) nanoparticles. Contaminant removal mechanisms by magnetic nanoparticles are presented, along with factors affecting the ability of contaminant desorption. Factors influencing the recovery of magnetic nanoparticles are outlined, describing the challenges of magnetic particle collection. The aggregation of magnetic nanoparticles is described, and methods for enhancing stability are summarized. Moreover, the toxicological effects owing to magnetic nanoparticles are discussed. It is possible that magnetic nanoparticles can be applied sustainably after detailed consideration of these discussed factors.","Magnetic nanoparticles: essential factors for sustainable environmental applications Abs: In recent years, there has been an increasing use of engineered magnetic nanoparticles for remediation and water treatments, leading to elevated public concerns. To this end, it is necessary to enhance the understanding of how these magnetic nanoparticles react with contaminants and interact with the surrounding environment during applications. This review aims to provide a holistic overview of current knowledge of magnetic nanoparticles in environmental applications, emphasizing studies of zero-valent iron (nZVI), magnetite (Fe3O4) and maghemite (?-Fe2O3) nanoparticles. Contaminant removal mechanisms by magnetic nanoparticles are presented, along with factors affecting the ability of contaminant desorption. Factors influencing the recovery of magnetic nanoparticles are outlined, describing the challenges of magnetic particle collection. The aggregation of magnetic nanoparticles is described, and methods for enhancing stability are summarized. Moreover, the toxicological effects owing to magnetic nanoparticles are discussed. It is possible that magnetic nanoparticles can be applied sustainably after detailed consideration of these discussed factors."
1786417,Suzuki et al. 2013,Radiotracer estimates of benthic activity effects on trace metal diffusion into mangrove sediments,"Potential influences of the whole benthic organisms' activity (i.e., coupled faunal and microbial effects) on (58)Co, (51)Cr and (65)Zn diffusion into surface mangrove sediment layers (0-6 cm depth) were evaluated in 36 h experiments. Benthic activity indices (BAI) were proposed, calculated as the relative percent difference between untreated sediments and formaldehyde-treated sediments data in relation to untreated sediments data. Benthic activity was estimated as responsible for 32%-44% of total inventories within sediments, being the chromate anion spiked the less affected radiotracer, while (65)Zn was the most sensitive. Benthic activity was quantitatively evidenced as a control on trace metal diffusion into the sediments, contributing to determine the sediment role as a metal sink. This influence can also affect metal potential bioavailability, considering that recently diffused metals can be more readily available to biological uptake.","Radiotracer estimates of benthic activity effects on trace metal diffusion into mangrove sediments Abs: Potential influences of the whole benthic organisms' activity (i.e., coupled faunal and microbial effects) on (58)Co, (51)Cr and (65)Zn diffusion into surface mangrove sediment layers (0-6 cm depth) were evaluated in 36 h experiments. Benthic activity indices (BAI) were proposed, calculated as the relative percent difference between untreated sediments and formaldehyde-treated sediments data in relation to untreated sediments data. Benthic activity was estimated as responsible for 32%-44% of total inventories within sediments, being the chromate anion spiked the less affected radiotracer, while (65)Zn was the most sensitive. Benthic activity was quantitatively evidenced as a control on trace metal diffusion into the sediments, contributing to determine the sediment role as a metal sink. This influence can also affect metal potential bioavailability, considering that recently diffused metals can be more readily available to biological uptake."
1786416,Sungur et al. 2013,Determination of Chromium Species in Various Medicinal Plants Consumed in Hatay Region in Turkey,,Determination of Chromium Species in Various Medicinal Plants Consumed in Hatay Region in Turkey Abs: 
1786415,Sun et al. 2013,Removal of low concentration Cr(VI) from aqueous solution by modified wheat straw,,Removal of low concentration Cr(VI) from aqueous solution by modified wheat straw Abs: 
1786414,Sugashini and  Sheriffa begum 2013,Column Adsorption Studies for the Removal of Cr(VI) Ions by Ethylamine Modified Chitosan Carbonized Rice Husk Composite Beads with Modelling and Optimization,,Column Adsorption Studies for the Removal of Cr(VI) Ions by Ethylamine Modified Chitosan Carbonized Rice Husk Composite Beads with Modelling and Optimization Abs: 
1786413,Su et al. 2013,"Spatial determinants of hazardous chemicals in surface water of Qiantang River, China",,"Spatial determinants of hazardous chemicals in surface water of Qiantang River, China Abs: "
1786412,Stasinos and  Zabetakis 2013,"The uptake of nickel and chromium from irrigation water by potatoes, carrots and onions","Heavy metals, in general, can migrate from polluted soil and/or irrigation water to tuber plants, leading, after chronic consumption, to health problems. The scope of this study was to investigate the uptake of chromium and nickel by carrots (Daucus carrota), onions (Allium cepa) and potatoes (Solanum tuberosum) in a greenhouse experiment simulating the open-field irrigation conditions in the two biggest tuber producing regions of Greece (Asopos river in Viotia and Messapia in Evia). The study included cultivation of tubers for a period of approximately 4 months in six irrigation lines, each one provided by a water solution containing different levels of Cr(VI) and Ni(II) ranging from 0?g/l (control) to 250?g/l. The soil used was obtained from a certified organic greenhouse. Uptake of Cr was observed in onion leaves between 0 and 10?g/l water concentrations (+109.2 percent, p=0.006), 0?g/l and 20?g/l (+47.5 percent, p=0.006), 0?g/l and 50?g/l (+202.8 percent, p=0.006), 0?g/l and 100?g/l (+89.9 percent, p=0.028), 0?g/l and 250?g/l (+61.3 percent, p=0.009). Uptake of Ni was observed: (a) in onion leaves between 0 and 250?g/l water concentrations (+90.2 percent, p=0.076), (b) in onion shoots between 0 and 10?g/l (+39.1 percent, p=0.045), 0 and 250?g/l (+55 percent, p=0.047) and (c) in potatoes between 0 and 20?g/l (+28.1 percent, p=0.083). Our results suggest that irrigation water containing Cr and Ni can cross-contaminate onions and potatoes cultivated in a soil never previously polluted, anthropogenically, with heavy metals. No such results were found for carrots.","The uptake of nickel and chromium from irrigation water by potatoes, carrots and onions Abs: Heavy metals, in general, can migrate from polluted soil and/or irrigation water to tuber plants, leading, after chronic consumption, to health problems. The scope of this study was to investigate the uptake of chromium and nickel by carrots (Daucus carrota), onions (Allium cepa) and potatoes (Solanum tuberosum) in a greenhouse experiment simulating the open-field irrigation conditions in the two biggest tuber producing regions of Greece (Asopos river in Viotia and Messapia in Evia). The study included cultivation of tubers for a period of approximately 4 months in six irrigation lines, each one provided by a water solution containing different levels of Cr(VI) and Ni(II) ranging from 0?g/l (control) to 250?g/l. The soil used was obtained from a certified organic greenhouse. Uptake of Cr was observed in onion leaves between 0 and 10?g/l water concentrations (+109.2 percent, p=0.006), 0?g/l and 20?g/l (+47.5 percent, p=0.006), 0?g/l and 50?g/l (+202.8 percent, p=0.006), 0?g/l and 100?g/l (+89.9 percent, p=0.028), 0?g/l and 250?g/l (+61.3 percent, p=0.009). Uptake of Ni was observed: (a) in onion leaves between 0 and 250?g/l water concentrations (+90.2 percent, p=0.076), (b) in onion shoots between 0 and 10?g/l (+39.1 percent, p=0.045), 0 and 250?g/l (+55 percent, p=0.047) and (c) in potatoes between 0 and 20?g/l (+28.1 percent, p=0.083). Our results suggest that irrigation water containing Cr and Ni can cross-contaminate onions and potatoes cultivated in a soil never previously polluted, anthropogenically, with heavy metals. No such results were found for carrots."
1786411,Stalin et al. 2013,Effects of (60)Co gamma irradiation on behavior and gill histoarchitecture of giant fresh water prawn Macrobrachium rosenbergii (DE MAN),"Present study was designed to observe the effects of (60)Co gamma radiation in behavioral and histological changes in the gills of giant fresh water prawn Macrobrachium rosenbergii. The adult prawns were irradiated with four different dose levels (3mGy, 30mGy, 300mGy and 3000mGy) and the control group (without irradiation) was maintained separately. Behavioral changes like hyperactivity, loss of balance, reduced swimming rate, slower rate of food intake and convulsions were observed in higher dose levels of 300mGy and 3000mGy. The histological alterations such as accumulated haemocytes in haemocoelic spaces, abnormal gill tips, lifted lamellar epithelium, swollen and fused lamellae, hyperplasic, necrotic, clavate-globate and complete disorganization of lamellae were observed in (60)Co gamma irradiated prawns. Significantly more considerable histological alterations were observed in the highest dose level of 3000mGy, but no mortality was evidenced. This study serves as biomonitoring tool to assess the radiation pollution in the aquatic environment.","Effects of (60)Co gamma irradiation on behavior and gill histoarchitecture of giant fresh water prawn Macrobrachium rosenbergii (DE MAN) Abs: Present study was designed to observe the effects of (60)Co gamma radiation in behavioral and histological changes in the gills of giant fresh water prawn Macrobrachium rosenbergii. The adult prawns were irradiated with four different dose levels (3mGy, 30mGy, 300mGy and 3000mGy) and the control group (without irradiation) was maintained separately. Behavioral changes like hyperactivity, loss of balance, reduced swimming rate, slower rate of food intake and convulsions were observed in higher dose levels of 300mGy and 3000mGy. The histological alterations such as accumulated haemocytes in haemocoelic spaces, abnormal gill tips, lifted lamellar epithelium, swollen and fused lamellae, hyperplasic, necrotic, clavate-globate and complete disorganization of lamellae were observed in (60)Co gamma irradiated prawns. Significantly more considerable histological alterations were observed in the highest dose level of 3000mGy, but no mortality was evidenced. This study serves as biomonitoring tool to assess the radiation pollution in the aquatic environment."
1786410,Sivakami et al. 2013,Preparation and characterization of nano chitosan for treatment wastewaters,"Chitosan nanorod with minimum particle size of &lt;100 nm was prepared by crosslinking low molecular weight chitosan with polyanion sodium tripolyphosphate and physicochemically characterized (FT-IR, XRD, SEM, AFM, TGA and DSC) for waste water treatment. Its sorption capacity and sorption isotherms for chromium (Cr) were studied. The effect of initial concentration of Cr ions, sorbent amount, agitation period and pH of solution that influence sorption capacity were also investigated. It was found that nanochitosan in the solid state was rod shaped which could sorb Cr (VI) to Cr (III) ions effectively. Based on the Langmuir, the Freundlich and the Temkin sorption isotherms, the sorption capacity of chitosan nanoparticles is very high and the adsorbent favors multilayer adsorption. The kinetics studies show that the adsorption follows the pseudo-second-order kinetics, which infers the transformation of Cr (VI) to Cr (III). From the results it was concluded that nanochitosan is an excellent material as a biosorbent for Cr removal from water.","Preparation and characterization of nano chitosan for treatment wastewaters Abs: Chitosan nanorod with minimum particle size of &lt;100 nm was prepared by crosslinking low molecular weight chitosan with polyanion sodium tripolyphosphate and physicochemically characterized (FT-IR, XRD, SEM, AFM, TGA and DSC) for waste water treatment. Its sorption capacity and sorption isotherms for chromium (Cr) were studied. The effect of initial concentration of Cr ions, sorbent amount, agitation period and pH of solution that influence sorption capacity were also investigated. It was found that nanochitosan in the solid state was rod shaped which could sorb Cr (VI) to Cr (III) ions effectively. Based on the Langmuir, the Freundlich and the Temkin sorption isotherms, the sorption capacity of chitosan nanoparticles is very high and the adsorbent favors multilayer adsorption. The kinetics studies show that the adsorption follows the pseudo-second-order kinetics, which infers the transformation of Cr (VI) to Cr (III). From the results it was concluded that nanochitosan is an excellent material as a biosorbent for Cr removal from water."
1786409,Siqueira and  Aprile 2013,"Avaliação de risco ambiental por contaminação metálica e material orgânico em sedimentos da bacia do Rio Aurá, Região Metropolitana de Belém - PA",,"Avaliação de risco ambiental por contaminação metálica e material orgânico em sedimentos da bacia do Rio Aurá, Região Metropolitana de Belém - PA Abs: "
1786408,Singh et al. 2013,Evaluation of Pseudomonas aeruginosa an innovative bioremediation tool in multi metals ions from simulated system using multi response methodology,"Under certain conditions bacteria can act as a good biosorbent towards heavy metals in simultaneous removal from effluents. The present study explores overlay plots of multi response surface methodology for simulated wastewater treatment potential. Pseudomonas aeruginosa was used for bioremediation of metallic ions, where removal of Cd (80-90%), Mn (85-90%), Fe (50-55%), Cr (70-75%) can be achieved by fixing the pH, oxidation reduction potential (mV) and one of the metallic constituent in the simulated effluent. The metal ions Cd and Cr (T), Fe and ORP (mV) are relatively closely located to each other in the loading plot indicating co-variance between these components. However Cr(VI) transformation and Mn removal are distantly placed in the bi-plot indicating the existed significant difference. Elevated reductase enzyme activity (31.75 ?g/minmg) observed in the isolate showing the ability to effectively reduce metals ions.","Evaluation of Pseudomonas aeruginosa an innovative bioremediation tool in multi metals ions from simulated system using multi response methodology Abs: Under certain conditions bacteria can act as a good biosorbent towards heavy metals in simultaneous removal from effluents. The present study explores overlay plots of multi response surface methodology for simulated wastewater treatment potential. Pseudomonas aeruginosa was used for bioremediation of metallic ions, where removal of Cd (80-90%), Mn (85-90%), Fe (50-55%), Cr (70-75%) can be achieved by fixing the pH, oxidation reduction potential (mV) and one of the metallic constituent in the simulated effluent. The metal ions Cd and Cr (T), Fe and ORP (mV) are relatively closely located to each other in the loading plot indicating co-variance between these components. However Cr(VI) transformation and Mn removal are distantly placed in the bi-plot indicating the existed significant difference. Elevated reductase enzyme activity (31.75 ?g/minmg) observed in the isolate showing the ability to effectively reduce metals ions."
1786407,Singh 2013,Mechanistic aspects of oxidation of dextrose by N-bromophthalimide in acidic medium: a micellar kinetic study,,Mechanistic aspects of oxidation of dextrose by N-bromophthalimide in acidic medium: a micellar kinetic study Abs: 
1786406,Shi et al. 2013,Simultaneous adsorption and degradation of Zn(2+) and Cu (2+) from wastewaters using nanoscale zero-valent iron impregnated with clays,"Clays such as kaolin, bentonite and zeolite were evaluated as support material for nanoscale zero-valent iron (nZVI) to simultaneously remove Cu(2+) and Zn(2+) from aqueous solution. Of the three supported nZVIs, bentonite-supported nZVI (B-nZVI) was most effective in the simultaneous removal of Cu(2+) and Zn(2+) from a aqueous solution containing a 100 mg/l of Cu(2+) and Zn(2+), where 92.9 % Cu(2+) and 58.3 % Zn(2+) were removed. Scanning electronic microscope (SEM) revealed that the aggregation of nZVI decreased as the proportion of bentonite increased due to the good dispersion of nZVI, while energy dispersive spectroscopy (EDS) demonstrated the deposition of copper and zinc on B-nZVI after B-nZVI reacted with Cu(2+) and Zn(2+). A kinetics study indicated that removing Cu(2+) and Zn(2+) with B-nZVI accorded with the pseudo first-order model. These suggest that simultaneous adsorption of Cu(2+)and Zn(2+) on bentonite and the degradation of Cu(2+)and Zn(2+) by nZVI on the bentonite. However, Cu(2+) removal by B-nZVI was reduced rather than adsorption, while Zn(2+) removal was main adsorption. Finally, Cu(2+), Zn(2+), Ni(2+), Pb(2+) and total Cr from various wastewaters were removed by B-nZVI, and reusability of B-nZVI with different treatment was tested, which demonstrates that B-nZVI is a potential material for the removal of heavy metals from wastewaters.","Simultaneous adsorption and degradation of Zn(2+) and Cu (2+) from wastewaters using nanoscale zero-valent iron impregnated with clays Abs: Clays such as kaolin, bentonite and zeolite were evaluated as support material for nanoscale zero-valent iron (nZVI) to simultaneously remove Cu(2+) and Zn(2+) from aqueous solution. Of the three supported nZVIs, bentonite-supported nZVI (B-nZVI) was most effective in the simultaneous removal of Cu(2+) and Zn(2+) from a aqueous solution containing a 100 mg/l of Cu(2+) and Zn(2+), where 92.9 % Cu(2+) and 58.3 % Zn(2+) were removed. Scanning electronic microscope (SEM) revealed that the aggregation of nZVI decreased as the proportion of bentonite increased due to the good dispersion of nZVI, while energy dispersive spectroscopy (EDS) demonstrated the deposition of copper and zinc on B-nZVI after B-nZVI reacted with Cu(2+) and Zn(2+). A kinetics study indicated that removing Cu(2+) and Zn(2+) with B-nZVI accorded with the pseudo first-order model. These suggest that simultaneous adsorption of Cu(2+)and Zn(2+) on bentonite and the degradation of Cu(2+)and Zn(2+) by nZVI on the bentonite. However, Cu(2+) removal by B-nZVI was reduced rather than adsorption, while Zn(2+) removal was main adsorption. Finally, Cu(2+), Zn(2+), Ni(2+), Pb(2+) and total Cr from various wastewaters were removed by B-nZVI, and reusability of B-nZVI with different treatment was tested, which demonstrates that B-nZVI is a potential material for the removal of heavy metals from wastewaters."
1786405,Serpi et al. 2013,Adsorptive transfer voltammetry applied to the study of chromium-induced DNA damage in the presence of curcumin,,Adsorptive transfer voltammetry applied to the study of chromium-induced DNA damage in the presence of curcumin Abs: 
1786404,Sengupta 2013,Environmental and occupational exposure of metals and their role in male reproductive functions,"This review summarizes the effects of more than 20 metals that, research has indicated, may influence male reproductive health. Though males lack an apparent, easily measurable reproductive cycle, progress has been made in evaluating tests to identify chemical hazards and estimate reproductive health risks. Some agents discussed in this review are well known to have potential toxic effects on the male reproductive system, whereas some are not so well established in toxicology. This review attempts to cover most of the known toxicants and their effects on male fertility. The literature suggests a need for further research in those chemicals that are reactive and capable of covalent interactions in biological systems, as well as those defined as mutagens and/or carcinogens, to cause aneuploidy or other chromosomal aberrations, affect sperm motility in vitro, share hormonal activity or affect hormone action, and those that act directly or indirectly to affect the hypothalamo-pituitary-gonadal axis.","Environmental and occupational exposure of metals and their role in male reproductive functions Abs: This review summarizes the effects of more than 20 metals that, research has indicated, may influence male reproductive health. Though males lack an apparent, easily measurable reproductive cycle, progress has been made in evaluating tests to identify chemical hazards and estimate reproductive health risks. Some agents discussed in this review are well known to have potential toxic effects on the male reproductive system, whereas some are not so well established in toxicology. This review attempts to cover most of the known toxicants and their effects on male fertility. The literature suggests a need for further research in those chemicals that are reactive and capable of covalent interactions in biological systems, as well as those defined as mutagens and/or carcinogens, to cause aneuploidy or other chromosomal aberrations, affect sperm motility in vitro, share hormonal activity or affect hormone action, and those that act directly or indirectly to affect the hypothalamo-pituitary-gonadal axis."
1786403,Schauwecker et al. 2013,Performance of wood treated with prospective organic surface protectants upon outdoor exposure: FTIR spectroscopic analysis of weathered surfaces,,Performance of wood treated with prospective organic surface protectants upon outdoor exposure: FTIR spectroscopic analysis of weathered surfaces Abs: 
1786402,Scaglia et al. 2013,Cr(VI) reduction capability of humic acid extracted from the organic component of municipal solid waste,"The capacity of humic acid extracted from organic waste (HAw) to reduce Cr(VI) was tested at pH 2.5, 4 and 6 and compared with coal-derived humic acid (HAc). HAw was more effective than HAc in reducing Cr(VI). The kinetics of Cr(VI) reductions depended strongly on pH. The calculation of the apparent rate coefficients indicated that HAw was more efficient at reducing Cr(VI) than HAc, but was also more efficient than HAs from soil and peat. The reduction capability of HAs depends on the type of functional groups (i.e., thiols and phenols) present, rather than the free radicals. HAw was more efficient at reducing Cr(VI) than HAc because more reactive phenols were present, i.e., methoxy- and methyl-phenols.","Cr(VI) reduction capability of humic acid extracted from the organic component of municipal solid waste Abs: The capacity of humic acid extracted from organic waste (HAw) to reduce Cr(VI) was tested at pH 2.5, 4 and 6 and compared with coal-derived humic acid (HAc). HAw was more effective than HAc in reducing Cr(VI). The kinetics of Cr(VI) reductions depended strongly on pH. The calculation of the apparent rate coefficients indicated that HAw was more efficient at reducing Cr(VI) than HAc, but was also more efficient than HAs from soil and peat. The reduction capability of HAs depends on the type of functional groups (i.e., thiols and phenols) present, rather than the free radicals. HAw was more efficient at reducing Cr(VI) than HAc because more reactive phenols were present, i.e., methoxy- and methyl-phenols."
1786401,Sattari et al. 2013,Chromate removal using novel modified MCM-41 nanoporous silica: synthesis and characterization of novel terpyridine-modified MCM-41,"Novel terpyridine-functionalized MCM-41 nanoporous silica was synthesized and characterized by X-ray powder diffraction (XRD), infrared (IR) spectroscopy, transmission electron microscopy (TEM), and thermal (TGA-DSC) and elemental analyses. The application of functionalized nanoporous silica was investigated for the removal of chromate, which is one of the most harmful pollutants in the environment. The effects of several parameters including the sample pH, adsorption kinetic and maximum adsorption capacity of functionalized nanoporous silica in the removal of chromate were studied.","Chromate removal using novel modified MCM-41 nanoporous silica: synthesis and characterization of novel terpyridine-modified MCM-41 Abs: Novel terpyridine-functionalized MCM-41 nanoporous silica was synthesized and characterized by X-ray powder diffraction (XRD), infrared (IR) spectroscopy, transmission electron microscopy (TEM), and thermal (TGA-DSC) and elemental analyses. The application of functionalized nanoporous silica was investigated for the removal of chromate, which is one of the most harmful pollutants in the environment. The effects of several parameters including the sample pH, adsorption kinetic and maximum adsorption capacity of functionalized nanoporous silica in the removal of chromate were studied."
1786400,Samuel et al. 2013,Batch and continuous flow studies of adsorptive removal of Cr(VI) by adapted bacterial consortia immobilized in alginate beads,"The adsorptive removal of Cr(VI) by alginate beads containing Cr(VI)-adapted Acinetobacter junii, Escherichia coli and Bacillus subtilis in batch and continuous packed bed column reactors was investigated. Under optimized conditions (pH 3.0; contact time, 180 min; 30 °C; initial Cr(VI) concentration of 100 mg/L), 65.86 mg/g adsorption capacity was recorded in the batch study. When an adsorbent dosage of 1g/L, a flow rate of 5 mL/min, a bed height of 20 cm, an initial Cr(VI) concentration of 300 mg/L was employed, a capacity of 657 mg/g was noted for the continuous column assay. The batch sorption data followed the Langmuir isotherm and pseudo second order kinetics. Five sorption/desorption cycles yielded 100%, 99.63%, 95.31%, 80.7% and 74.22% regeneration, respectively. Cr(VI) adsorption studies using spiked ground water, freshwater and domestic wastewater in a packed bed reactor demonstrated Cr(VI) removals of 64.8%, 55.08%, 56.86% respectively. Cr(VI) sorption on immobilized bacteria was confirmed with Fourier-transform infrared and Energy dispersive X-ray spectroscopy.","Batch and continuous flow studies of adsorptive removal of Cr(VI) by adapted bacterial consortia immobilized in alginate beads Abs: The adsorptive removal of Cr(VI) by alginate beads containing Cr(VI)-adapted Acinetobacter junii, Escherichia coli and Bacillus subtilis in batch and continuous packed bed column reactors was investigated. Under optimized conditions (pH 3.0; contact time, 180 min; 30 °C; initial Cr(VI) concentration of 100 mg/L), 65.86 mg/g adsorption capacity was recorded in the batch study. When an adsorbent dosage of 1g/L, a flow rate of 5 mL/min, a bed height of 20 cm, an initial Cr(VI) concentration of 300 mg/L was employed, a capacity of 657 mg/g was noted for the continuous column assay. The batch sorption data followed the Langmuir isotherm and pseudo second order kinetics. Five sorption/desorption cycles yielded 100%, 99.63%, 95.31%, 80.7% and 74.22% regeneration, respectively. Cr(VI) adsorption studies using spiked ground water, freshwater and domestic wastewater in a packed bed reactor demonstrated Cr(VI) removals of 64.8%, 55.08%, 56.86% respectively. Cr(VI) sorption on immobilized bacteria was confirmed with Fourier-transform infrared and Energy dispersive X-ray spectroscopy."
1786399,Saha et al. 2013,Removal of hexavalent chromium from water by adsorption on mosambi (Citrus limetta) peel,,Removal of hexavalent chromium from water by adsorption on mosambi (Citrus limetta) peel Abs: 
1786398,Saha et al. 2013,Choice of a suitable hetero-aromatic nitrogen base as promoter for chromic acid oxidation of dl-mandelic acid in aqueous media at room temperature,,Choice of a suitable hetero-aromatic nitrogen base as promoter for chromic acid oxidation of dl-mandelic acid in aqueous media at room temperature Abs: 
1786397,Rudnitskaya et al. 2013,Potentiometric chemical sensors from lignin-poly(propylene oxide) copolymers doped by carbon nanotubes,"Hardwood and softwood lignins obtained from industrial sulphite and kraft and laboratory oxygen-organosolv pulping processes were employed in co-polymerization with tolylene 2,4-diisocyanate terminated poly(propylene glycol). The obtained lignin-based polyurethanes were doped with 0.72 w/w% of multiwall carbon nanotubes (MWCNTs) with the aim of increasing their electrical conductivity to the levels suitable for sensor applications. Effects of the polymer doping with MWCNTs were assessed using electrical impedance (EIS) and UV-Resonance Raman (UV-RR) spectroscopy. Potentiometric sensors were prepared by drop casting of liquid polymer on the surface of carbon glass or platinum electrodes. Lignin-based sensors displayed a very low or no sensitivity to all alkali, alkali-earth and transition metal cations ions except Cr(VI) at pH 2. Response to Cr(VI) values of 39, 50 and 53 mV pX(-1) for the sensors based on kraft, organosolv and lignosulphonate lignins, respectively, were observed. Redox sensitivity values close to the theoretical values of 20 and 21 mV pX(-1) for organosolv and lignosulphonate based sensors respectively were detected in the Cr(III)/Cr(VI) solutions while a very low response was observed in the solutions containing Fe(CN)(6)(3-/4-). Conducting composite lignin-based polyurethanes doped with MWCNTs were suggested as being promising materials for Cr(VI)-sensitive potentiometric sensors.","Potentiometric chemical sensors from lignin-poly(propylene oxide) copolymers doped by carbon nanotubes Abs: Hardwood and softwood lignins obtained from industrial sulphite and kraft and laboratory oxygen-organosolv pulping processes were employed in co-polymerization with tolylene 2,4-diisocyanate terminated poly(propylene glycol). The obtained lignin-based polyurethanes were doped with 0.72 w/w% of multiwall carbon nanotubes (MWCNTs) with the aim of increasing their electrical conductivity to the levels suitable for sensor applications. Effects of the polymer doping with MWCNTs were assessed using electrical impedance (EIS) and UV-Resonance Raman (UV-RR) spectroscopy. Potentiometric sensors were prepared by drop casting of liquid polymer on the surface of carbon glass or platinum electrodes. Lignin-based sensors displayed a very low or no sensitivity to all alkali, alkali-earth and transition metal cations ions except Cr(VI) at pH 2. Response to Cr(VI) values of 39, 50 and 53 mV pX(-1) for the sensors based on kraft, organosolv and lignosulphonate lignins, respectively, were observed. Redox sensitivity values close to the theoretical values of 20 and 21 mV pX(-1) for organosolv and lignosulphonate based sensors respectively were detected in the Cr(III)/Cr(VI) solutions while a very low response was observed in the solutions containing Fe(CN)(6)(3-/4-). Conducting composite lignin-based polyurethanes doped with MWCNTs were suggested as being promising materials for Cr(VI)-sensitive potentiometric sensors."
1786396,Rouff 2013,Temperature-dependent phosphorus precipitation and chromium removal from struvite-saturated solutions,"The effect of temperature from 25 to 300°C on the precipitation of phosphorus (P) from struvite-saturated (MgNH(4)PO(4)·6H(2)O) solutions was explored. Scanning electron microscopy (SEM) revealed reduced particle size and a change in morphology from elongated to rhombohedral crystals with temperature. X-ray diffraction (XRD) and Fourier transform infrared spectroscopy (FT-IR) indicated that at 25°C, the precipitate was struvite, while newberyite (MgHPO(4)·3H(2)O) formed at 100°C, and magnesium pyrophosphate (Mg(2)P(2)O(7)) at 300°C. Increased temperature reduced the association of ammonium and water of crystallization with the solid and increased P polymerization. The behavior of dissolved chromium (Cr) under these conditions was also assessed. Removal of Cr with the solid phase from Cr(III) solutions was observed at all temperatures, whereas removal from Cr(VI) solutions was significant only at 300°C. X-ray absorption fine structure spectroscopy (XAFS) revealed that regardless of initial oxidation state in solution, Cr(III) was associated with the solid, interacting by the adsorption of short-range Cr polymers. Therefore, for struvite-saturated solutions, increasing the temperature changed both the mineralogy of the P phase recovered and enhanced the interaction of otherwise unreactive Cr(VI) with the substrate. These results have implications for the temperature-enhanced recovery of P from wastewater.","Temperature-dependent phosphorus precipitation and chromium removal from struvite-saturated solutions Abs: The effect of temperature from 25 to 300°C on the precipitation of phosphorus (P) from struvite-saturated (MgNH(4)PO(4)·6H(2)O) solutions was explored. Scanning electron microscopy (SEM) revealed reduced particle size and a change in morphology from elongated to rhombohedral crystals with temperature. X-ray diffraction (XRD) and Fourier transform infrared spectroscopy (FT-IR) indicated that at 25°C, the precipitate was struvite, while newberyite (MgHPO(4)·3H(2)O) formed at 100°C, and magnesium pyrophosphate (Mg(2)P(2)O(7)) at 300°C. Increased temperature reduced the association of ammonium and water of crystallization with the solid and increased P polymerization. The behavior of dissolved chromium (Cr) under these conditions was also assessed. Removal of Cr with the solid phase from Cr(III) solutions was observed at all temperatures, whereas removal from Cr(VI) solutions was significant only at 300°C. X-ray absorption fine structure spectroscopy (XAFS) revealed that regardless of initial oxidation state in solution, Cr(III) was associated with the solid, interacting by the adsorption of short-range Cr polymers. Therefore, for struvite-saturated solutions, increasing the temperature changed both the mineralogy of the P phase recovered and enhanced the interaction of otherwise unreactive Cr(VI) with the substrate. These results have implications for the temperature-enhanced recovery of P from wastewater."
1786395,Rodriguez et al. 2013,Exposure to Cr(VI) induces organ dependent MSI in two loci related with photophosphorylation and with glutamine metabolism,"Chromium (Cr), as a mutagenic agent in plants, has received less attention than other metal pollutants. To understand if Cr induces microsatellite instability (MSI), Pisum sativum seedlings were exposed for 28 days to different concentrations of Cr(VI) up to 2000mgL(-1), and the genetic instability of ten microsatellites (SSRs) was analyzed. In plants exposed to Cr(VI) up to 1000mg L(-1), MSI was never observed. However, roots exposed to 2000mgL(-1) displayed MSI in two of the loci analyzed, corresponding to a mutation rate of 8.3%. SSR2 (inserted in the locus for plastid photosystem I 24kDa light harvesting protein) and SSR6 (inserted in the locus for P. sativum glutamine synthetase) from Cr(VI)-treated roots presented alleles with, respectively, less 6bp and more 3bp than the corresponding controls. This report demonstrates that: (a) SSRs technique is sensitive to detect Cr-induced mutagenicity in plants, being Cr-induced-MSI dose and organ dependent (roots are more sensitive); (b) two Cr-sensitive loci are related with thylakoid photophosphorylation and with glutamine synthetase, respectively; (c) despite MSI is induced by Cr(VI), it only occurs in plants exposed to concentrations higher than 1000mgL(-1) (values rarely found in real scenarios). Considering these data, we also discuss the known functional changes induced by Cr(VI) in photosynthesis and in glutamine synthetase activity.","Exposure to Cr(VI) induces organ dependent MSI in two loci related with photophosphorylation and with glutamine metabolism Abs: Chromium (Cr), as a mutagenic agent in plants, has received less attention than other metal pollutants. To understand if Cr induces microsatellite instability (MSI), Pisum sativum seedlings were exposed for 28 days to different concentrations of Cr(VI) up to 2000mgL(-1), and the genetic instability of ten microsatellites (SSRs) was analyzed. In plants exposed to Cr(VI) up to 1000mg L(-1), MSI was never observed. However, roots exposed to 2000mgL(-1) displayed MSI in two of the loci analyzed, corresponding to a mutation rate of 8.3%. SSR2 (inserted in the locus for plastid photosystem I 24kDa light harvesting protein) and SSR6 (inserted in the locus for P. sativum glutamine synthetase) from Cr(VI)-treated roots presented alleles with, respectively, less 6bp and more 3bp than the corresponding controls. This report demonstrates that: (a) SSRs technique is sensitive to detect Cr-induced mutagenicity in plants, being Cr-induced-MSI dose and organ dependent (roots are more sensitive); (b) two Cr-sensitive loci are related with thylakoid photophosphorylation and with glutamine synthetase, respectively; (c) despite MSI is induced by Cr(VI), it only occurs in plants exposed to concentrations higher than 1000mgL(-1) (values rarely found in real scenarios). Considering these data, we also discuss the known functional changes induced by Cr(VI) in photosynthesis and in glutamine synthetase activity."
1786394,Reyes et al. 2013,Tight junction proteins and oxidative stress in heavy metals-induced nephrotoxicity,"Kidney is a target organ for heavy metals. They accumulate in several segments of the nephron and cause profound alterations in morphology and function. Acute intoxication frequently causes acute renal failure. The effects of chronic exposure have not been fully disclosed. In recent years increasing awareness of the consequences of their presence in the kidney has evolved. In this review we focus on the alterations induced by heavy metals on the intercellular junctions of the kidney. We describe that in addition to the proximal tubule, which has been recognized as the main site of accumulation and injury, other segments of the nephron, such as glomeruli, vessels, and distal nephron, show also deleterious effects. We also emphasize the participation of oxidative stress as a relevant component of the renal damage induced by heavy metals and the beneficial effect that some antioxidant drugs, such as vitamin A (all-trans-retinoic acid) and vitamin E ( ? -tocopherol), depict on the morphological and functional alterations induced by heavy metals.","Tight junction proteins and oxidative stress in heavy metals-induced nephrotoxicity Abs: Kidney is a target organ for heavy metals. They accumulate in several segments of the nephron and cause profound alterations in morphology and function. Acute intoxication frequently causes acute renal failure. The effects of chronic exposure have not been fully disclosed. In recent years increasing awareness of the consequences of their presence in the kidney has evolved. In this review we focus on the alterations induced by heavy metals on the intercellular junctions of the kidney. We describe that in addition to the proximal tubule, which has been recognized as the main site of accumulation and injury, other segments of the nephron, such as glomeruli, vessels, and distal nephron, show also deleterious effects. We also emphasize the participation of oxidative stress as a relevant component of the renal damage induced by heavy metals and the beneficial effect that some antioxidant drugs, such as vitamin A (all-trans-retinoic acid) and vitamin E ( ? -tocopherol), depict on the morphological and functional alterations induced by heavy metals."
1786393,Reboleira et al. 2013,Acute Toxicity of Copper Sulfate and Potassium Dichromate on Stygobiont Proasellus: General Aspects of Groundwater Ecotoxicology and Future Perspectives,,Acute Toxicity of Copper Sulfate and Potassium Dichromate on Stygobiont Proasellus: General Aspects of Groundwater Ecotoxicology and Future Perspectives Abs: 
1786392,Raun et al. 2013,Unanticipated potential cancer risk near metal recycling facilities,"Metal recycling is an important growing industry. Prior to this study, area sources consisting of metal recycling facilities fell in a category of limited regulatory scrutiny because of assumed low levels of annual emissions. Initiating with community complaints of nuisance from smoke, dust and odor, the Houston Department of Health and Human Services (HDHHS) began a monitoring program outside metal recycler facilities and found metal particulates in outdoor ambient air at levels which could pose a carcinogenic human health risk. In a study of five similar metal recycler facilities which used a torch cutting process, air downwind and outside the facility was sampled for eight hours between 6 and 10 times each over 18 months using a mobile laboratory. Ten background locations were also sampled. Iron, manganese, copper, chromium, nickel, lead, cobalt, cadmium and mercury were detected downwind of the metal recyclers at frequencies ranging from 100% of the time for iron to 2% of the time for mercury. Of these metals, chromium, nickel, lead, cobalt, cadmium and mercury were not detected in any sample in the background. Two pairs of samples were analyzed for total chromium and hexavalent chromium to establish a ratio of the fraction of hexavalent chromium in total chromium. This fraction was used to estimate hexavalent chromium at all locations. The carcinogenic risk posed to a residential receptor from metal particulate matter concentrations in the ambient air attributed to the metal recyclers was estimated from each of the five facilities in an effort to rank the importance of this source and inform the need for further investigation. The total risk from these area sources ranged from an increased cancer risk of 1 in 1,000,000 to 6 in 10,000 using the 95th upper confidence limit of the mean of the carcinogenic metal particulate matter concentration, assuming the point of the exposure is the sample location for a residential receptor after accounting for wind direction and the number of shifts that could operate a year. Further study is warranted to better understand the metal air pollution levels in the community and if necessary, to evaluate the feasibility of emission controls and identify operational improvements and best management practices for this industry. This research adds two new aspects to the literature: identification of types and magnitude of metal particulate matter air pollutants associated with a previously unrecognized area source, metal recyclers and their potential risk to health. (c) 2013 Elsevier Inc. All rights reserved.","Unanticipated potential cancer risk near metal recycling facilities Abs: Metal recycling is an important growing industry. Prior to this study, area sources consisting of metal recycling facilities fell in a category of limited regulatory scrutiny because of assumed low levels of annual emissions. Initiating with community complaints of nuisance from smoke, dust and odor, the Houston Department of Health and Human Services (HDHHS) began a monitoring program outside metal recycler facilities and found metal particulates in outdoor ambient air at levels which could pose a carcinogenic human health risk. In a study of five similar metal recycler facilities which used a torch cutting process, air downwind and outside the facility was sampled for eight hours between 6 and 10 times each over 18 months using a mobile laboratory. Ten background locations were also sampled. Iron, manganese, copper, chromium, nickel, lead, cobalt, cadmium and mercury were detected downwind of the metal recyclers at frequencies ranging from 100% of the time for iron to 2% of the time for mercury. Of these metals, chromium, nickel, lead, cobalt, cadmium and mercury were not detected in any sample in the background. Two pairs of samples were analyzed for total chromium and hexavalent chromium to establish a ratio of the fraction of hexavalent chromium in total chromium. This fraction was used to estimate hexavalent chromium at all locations. The carcinogenic risk posed to a residential receptor from metal particulate matter concentrations in the ambient air attributed to the metal recyclers was estimated from each of the five facilities in an effort to rank the importance of this source and inform the need for further investigation. The total risk from these area sources ranged from an increased cancer risk of 1 in 1,000,000 to 6 in 10,000 using the 95th upper confidence limit of the mean of the carcinogenic metal particulate matter concentration, assuming the point of the exposure is the sample location for a residential receptor after accounting for wind direction and the number of shifts that could operate a year. Further study is warranted to better understand the metal air pollution levels in the community and if necessary, to evaluate the feasibility of emission controls and identify operational improvements and best management practices for this industry. This research adds two new aspects to the literature: identification of types and magnitude of metal particulate matter air pollutants associated with a previously unrecognized area source, metal recyclers and their potential risk to health. (c) 2013 Elsevier Inc. All rights reserved."
1786391,Raous et al. 2013,Potentially toxic metals in ultramafic mining materials: Identification of the main bearing and reactive phases,,Potentially toxic metals in ultramafic mining materials: Identification of the main bearing and reactive phases Abs: 
1786390,Ranieri et al. 2013,A Comparison Between Phragmites australis and Helianthus annuus in Chromium Phytoextraction,,A Comparison Between Phragmites australis and Helianthus annuus in Chromium Phytoextraction Abs: 
1786389,Rai et al. 2013,Chromate tolerance and accumulation in Chlorella vulgaris L.: role of antioxidant enzymes and biochemical changes in detoxification of metals,"A concentration-dependent increase in activity of antioxidant enzymes (catalase, ascorbate peroxidase, glutathione, superoxide dismutase) and carotenoid, MDA level have been observed in the green alga Chlorella vulgaris following chromium exposure at different concentrations (0.01-100 ?g ml(-1)). Simultaneously, decrease in growth rate, chlorophyll and protein contents was observed. In case of ascorbate peroxidase, glutathione peroxidase and superoxide dismutase a bell shaped dose response was evident, however, lipid peroxidation followed a linear relationship along with catalase activity, which could be used as biomarker of Cr toxicity and played important role in providing tolerance and subsequently, high accumulation potential of chromium in C. vulgaris. In present investigation, the green alga C. vulgaris respond better under chromium stress in terms of tolerance, growth and metal accumulating potential at higher concentration of Cr (VI) which could be employed in decontamination of chromium for environmental cleanup.","Chromate tolerance and accumulation in Chlorella vulgaris L.: role of antioxidant enzymes and biochemical changes in detoxification of metals Abs: A concentration-dependent increase in activity of antioxidant enzymes (catalase, ascorbate peroxidase, glutathione, superoxide dismutase) and carotenoid, MDA level have been observed in the green alga Chlorella vulgaris following chromium exposure at different concentrations (0.01-100 ?g ml(-1)). Simultaneously, decrease in growth rate, chlorophyll and protein contents was observed. In case of ascorbate peroxidase, glutathione peroxidase and superoxide dismutase a bell shaped dose response was evident, however, lipid peroxidation followed a linear relationship along with catalase activity, which could be used as biomarker of Cr toxicity and played important role in providing tolerance and subsequently, high accumulation potential of chromium in C. vulgaris. In present investigation, the green alga C. vulgaris respond better under chromium stress in terms of tolerance, growth and metal accumulating potential at higher concentration of Cr (VI) which could be employed in decontamination of chromium for environmental cleanup."
1786388,Quintelas et al. 2013,"Bioremoval of diethylketone by the synergistic combination of microorganisms and clays: uptake, removal and kinetic studies","The performance of two bacteria, Arthrobacter viscosus and Streptococcus equisimilis, and the effect of the interaction of these bacteria with four different clays on the retention of diethylketone were investigated in batch experiments. The uptake, the removal percentages and the kinetics of the processes were determined. S. equisimilis, by itself, had the best performance in terms of removal percentage, for all the initial diethylketone concentrations tested: 200, 350 and 700 mg/L. The uptake values are similar for both bacteria. A possible mechanism to explain the removal of diethylketone includes its degradation by bacteria, followed by the adsorption of the intermediates/sub-products by the functional groups present on the cells' surfaces. The assays performed with bacteria and clays indicated that the uptake values are similar despite of the clay used, for the same microorganism and mass of clay, but in general, higher values are reached when S. equisimilis is used, compared to A. viscosus. Kinetic data were described by pseudo-first- and pseudo-second-order models.","Bioremoval of diethylketone by the synergistic combination of microorganisms and clays: uptake, removal and kinetic studies Abs: The performance of two bacteria, Arthrobacter viscosus and Streptococcus equisimilis, and the effect of the interaction of these bacteria with four different clays on the retention of diethylketone were investigated in batch experiments. The uptake, the removal percentages and the kinetics of the processes were determined. S. equisimilis, by itself, had the best performance in terms of removal percentage, for all the initial diethylketone concentrations tested: 200, 350 and 700 mg/L. The uptake values are similar for both bacteria. A possible mechanism to explain the removal of diethylketone includes its degradation by bacteria, followed by the adsorption of the intermediates/sub-products by the functional groups present on the cells' surfaces. The assays performed with bacteria and clays indicated that the uptake values are similar despite of the clay used, for the same microorganism and mass of clay, but in general, higher values are reached when S. equisimilis is used, compared to A. viscosus. Kinetic data were described by pseudo-first- and pseudo-second-order models."
1786387,Pillai et al. 2013,Biosorption of Cr(VI) from aqueous solution by chemically modified potato starch: equilibrium and kinetic studies,"The biosorption capacity of chemically modified potato starch (CPS) for Cr(VI) from aqueous solution was investigated. The materials derived from carbohydrates are biodegradable and are generally regarded as safe and environmentally acceptable. The hydroxyl, carboxyl and carbonyl groups are responsible for the biosorption process. In the present study, the influence of various important parameters such as pH, time, biosorbent dose and initial Cr(VI) concentration on the biosorption capacity were investigated. The isotherms such as Langmuir, Freundlich and Tempkin were studied. The Freundlich and the Redlich-Peterson isotherms had been well fitted the biosorption of Cr(VI) with chemically modified potato starch. The kinetics of Cr(VI) removal using chemically modified potato starch was well explained by second-order kinetic model. The thermodynamic parameters were also evaluated from the biosorption measurements. Among the various desorbing agents tested, 98.2 percent chromium recovery was achieved with 0.1molL(-1) NaOH.","Biosorption of Cr(VI) from aqueous solution by chemically modified potato starch: equilibrium and kinetic studies Abs: The biosorption capacity of chemically modified potato starch (CPS) for Cr(VI) from aqueous solution was investigated. The materials derived from carbohydrates are biodegradable and are generally regarded as safe and environmentally acceptable. The hydroxyl, carboxyl and carbonyl groups are responsible for the biosorption process. In the present study, the influence of various important parameters such as pH, time, biosorbent dose and initial Cr(VI) concentration on the biosorption capacity were investigated. The isotherms such as Langmuir, Freundlich and Tempkin were studied. The Freundlich and the Redlich-Peterson isotherms had been well fitted the biosorption of Cr(VI) with chemically modified potato starch. The kinetics of Cr(VI) removal using chemically modified potato starch was well explained by second-order kinetic model. The thermodynamic parameters were also evaluated from the biosorption measurements. Among the various desorbing agents tested, 98.2 percent chromium recovery was achieved with 0.1molL(-1) NaOH."
1786386,Pifferi et al. 2013,Electrodeposited nano-titania films for photocatalytic Cr(VI) reduction,,Electrodeposited nano-titania films for photocatalytic Cr(VI) reduction Abs: 
1786385,Peyghan et al. 2012,"Adsorption and Electronic Structure Study of Imidazole on (6,0) Zigzag Single-Walled Boron Nitride Nanotube",,"Adsorption and Electronic Structure Study of Imidazole on (6,0) Zigzag Single-Walled Boron Nitride Nanotube Abs: "
1786384,Pan and  Xu 2013,Synthesis of Spinel-Structure CuFe2O4 Nanoparticles and Their Effective Electrocatalysis Properties,,Synthesis of Spinel-Structure CuFe2O4 Nanoparticles and Their Effective Electrocatalysis Properties Abs: 
1786383,Pakshirajan et al. 2013,Cr(III) and Cr(VI) removal from aqueous solutions by cheaply available fruit waste and algal biomass,"This study compared the effectiveness of different biosorbents, viz. materials commonly present in natural treatment systems (Scenedesmus quadricauda and reed) and commonly produced fruit wastes (orange and banana peel) to remove Cr(III) and Cr(VI) from a synthetic wastewater simulating tannery wastewater. The Cr(III) removal efficiency followed the order S. quadricauda&gt;orange peel&gt;banana peel&gt;reed, whereas the Cr(VI) removal followed the order banana peel&gt;S. quadricauda&gt;reed&gt;orange peel. The chromium biosorption kinetics were governed by the intraparticle diffusion mechanism. Isotherm data obtained using the different biosorbents were fitted to the Langmuir, Freundlich, and SIPS models, revealing that the experimental data followed most closely the monolayer sorption theory-based Langmuir model than the other models. The maximum Cr(III) sorption capacity, calculated using the Langmuir model, was found to be 12 and 9 mg/g for S. quadricauda and orange peel, respectively, and the maximum Cr(VI) sorption capacity calculated for banana peel was 3 mg/g. The influence of biosorbent size, pH, solid-liquid ratio, and competing ions were examined for Cr(III) biosorption by S. quadricauda and orange peel and for Cr(VI) sorption by banana peel. The solution pH was found to be the most influential parameter affecting the biosorption process: whereas pH 5 was found to be optimum for maximum removal of Cr(III), Cr(VI) was best removed at a pH as low as 3. Interference to chromium sorption by various ions revealed that Cr(III) binding onto orange peel occurs through electrostatic forces, whereas Cr(VI) binding onto banana peel through non-electrostatic forces.","Cr(III) and Cr(VI) removal from aqueous solutions by cheaply available fruit waste and algal biomass Abs: This study compared the effectiveness of different biosorbents, viz. materials commonly present in natural treatment systems (Scenedesmus quadricauda and reed) and commonly produced fruit wastes (orange and banana peel) to remove Cr(III) and Cr(VI) from a synthetic wastewater simulating tannery wastewater. The Cr(III) removal efficiency followed the order S. quadricauda&gt;orange peel&gt;banana peel&gt;reed, whereas the Cr(VI) removal followed the order banana peel&gt;S. quadricauda&gt;reed&gt;orange peel. The chromium biosorption kinetics were governed by the intraparticle diffusion mechanism. Isotherm data obtained using the different biosorbents were fitted to the Langmuir, Freundlich, and SIPS models, revealing that the experimental data followed most closely the monolayer sorption theory-based Langmuir model than the other models. The maximum Cr(III) sorption capacity, calculated using the Langmuir model, was found to be 12 and 9 mg/g for S. quadricauda and orange peel, respectively, and the maximum Cr(VI) sorption capacity calculated for banana peel was 3 mg/g. The influence of biosorbent size, pH, solid-liquid ratio, and competing ions were examined for Cr(III) biosorption by S. quadricauda and orange peel and for Cr(VI) sorption by banana peel. The solution pH was found to be the most influential parameter affecting the biosorption process: whereas pH 5 was found to be optimum for maximum removal of Cr(III), Cr(VI) was best removed at a pH as low as 3. Interference to chromium sorption by various ions revealed that Cr(III) binding onto orange peel occurs through electrostatic forces, whereas Cr(VI) binding onto banana peel through non-electrostatic forces."
1786382,De Sousa et al. 2013,Insights into the electrochemical behaviour of composite materials: Monovacant polyoxometalates @ porous metal-organic framework,,Insights into the electrochemical behaviour of composite materials: Monovacant polyoxometalates @ porous metal-organic framework Abs: 
1786381,Oves et al. 2013,Chromium reducing and plant growth promoting novel strain Pseudomonas aeruginosa OSG41 enhance chickpea growth in chromium amended soils,,Chromium reducing and plant growth promoting novel strain Pseudomonas aeruginosa OSG41 enhance chickpea growth in chromium amended soils Abs: 
1786380,Oliveira et al. 2013,Proposition of a simple method for chromium (VI) determination in soils from remote places applying digital images: A case study from Brazilian Antarctic Station,,Proposition of a simple method for chromium (VI) determination in soils from remote places applying digital images: A case study from Brazilian Antarctic Station Abs: 
1786379,Novotnik et al. 2013,Chromate in food samples: an artefact of wrongly applied analytical methodology?,,Chromate in food samples: an artefact of wrongly applied analytical methodology? Abs: 
1786378,Niu et al. 2013,Absorption of Cr(VI) onto amino-modified titanate nanotubes using 2-bromoethylamine hydrobromide through SN2 reaction,"Unlike the complex reaction of grafting amino groups using harmful organic solvents, we proposed an environmental friendly method for effective amino grafting on titanate nanotubes (TNTs) with 2-Bromoethylamine hydrobromide (2-Bh) through a two-step SN2 reaction in pure water solution. The amino-modified titanate nanotubes (TNTs-RNH2) were characterized by Transmission electron microscope, X-ray diffraction, X-ray photoelectron spectroscopy and Fourier transform infrared spectroscopy. Under optimal conditions, the molar ratio of NaOH/2-Bh was 1.2 for step 1 and 1.3 for step 2 with corresponding reaction time of 12h and 24h, respectively. The adsorption isotherm of Cr(VI) onto TNTs-RNH2 well fits Langmuir model with maximal adsorption capacity of 69.1 mg/g, which is almost five times larger than that of fresh TNTs. The slight decrease in adsorption capacity with NO3(-) concentration was attributed to competition from ions, suppression of electric double layer and changes of Cr(VI) speciation. The wide adsorption pH range was due to much larger point of zero charge (8.2) and electrostatic attraction between positively charged TNTs-RNH2 and Cr(VI) with different speciations. The products could be well reused due to simple desorption at pH 10 with about 20% loss of the adsorption capacity after three recycles without any regeneration treatment.","Absorption of Cr(VI) onto amino-modified titanate nanotubes using 2-bromoethylamine hydrobromide through SN2 reaction Abs: Unlike the complex reaction of grafting amino groups using harmful organic solvents, we proposed an environmental friendly method for effective amino grafting on titanate nanotubes (TNTs) with 2-Bromoethylamine hydrobromide (2-Bh) through a two-step SN2 reaction in pure water solution. The amino-modified titanate nanotubes (TNTs-RNH2) were characterized by Transmission electron microscope, X-ray diffraction, X-ray photoelectron spectroscopy and Fourier transform infrared spectroscopy. Under optimal conditions, the molar ratio of NaOH/2-Bh was 1.2 for step 1 and 1.3 for step 2 with corresponding reaction time of 12h and 24h, respectively. The adsorption isotherm of Cr(VI) onto TNTs-RNH2 well fits Langmuir model with maximal adsorption capacity of 69.1 mg/g, which is almost five times larger than that of fresh TNTs. The slight decrease in adsorption capacity with NO3(-) concentration was attributed to competition from ions, suppression of electric double layer and changes of Cr(VI) speciation. The wide adsorption pH range was due to much larger point of zero charge (8.2) and electrostatic attraction between positively charged TNTs-RNH2 and Cr(VI) with different speciations. The products could be well reused due to simple desorption at pH 10 with about 20% loss of the adsorption capacity after three recycles without any regeneration treatment."
1786377,Nikagolla et al. 2013,Adsorption kinetics of chromium(III) removal from aqueous solutions using natural red earth,,Adsorption kinetics of chromium(III) removal from aqueous solutions using natural red earth Abs: 
1786376,Narayani and  Shetty 2013,Chromium-Resistant Bacteria and Their Environmental Condition for Hexavalent Chromium Removal: A Review,,Chromium-Resistant Bacteria and Their Environmental Condition for Hexavalent Chromium Removal: A Review Abs: 
1786375,Nammalwar et al. 2013,Efficient oxidation of arylmethylene compounds using nano-MnO2,,Efficient oxidation of arylmethylene compounds using nano-MnO2 Abs: 
1786374,Myers et al. 2013,Redox activation of Fe(III)-thiosemicarbazones and Fe(III)-bleomycin by thioredoxin reductase: specificity of enzymatic redox centers and analysis of reactive species formation by ESR spin trapping,"Thiosemicarbazones such as Triapine (Tp) and Dp44mT are tridentate iron (Fe) chelators that have well-documented antineoplastic activity. Although Fe-thiosemicarbazones can undergo redox cycling to generate reactive species that may have important roles in their cytotoxicity, there is only limited insight into specific cellular agents that can rapidly reduce Fe(III)-thiosemicarbazones and thereby promote their redox activity. Here we report that thioredoxin reductase-1 (TrxR1) and glutathione reductase (GR) have this activity and that there is considerable specificity to the interactions between specific redox centers in these enzymes and various Fe(III) complexes. Site-directed variants of TrxR1 demonstrate that the selenocysteine (Sec) of the enzyme is not required, whereas the C59 residue and the flavin have important roles. Although TrxR1 and GR have analogous C59/flavin motifs, TrxR is considerably faster than GR. For both enzymes, Fe(III)(Tp)2 is reduced faster than Fe(III)(Dp44mT)2. This reduction promotes redox cycling and the generation of hydroxyl radical (HO) in a peroxide-dependent manner, even with low-micromolar levels of Fe(Tp)2. TrxR also reduces Fe(III)-bleomycin and this activity is Sec-dependent. TrxR cannot reduce Fe(III)-EDTA at significant rates. Our findings are the first to demonstrate pro-oxidant reductive activation of Fe(III)-based antitumor thiosemicarbazones by interactions with specific enzyme species. The marked elevation of TrxR1 in many tumors could contribute to the selective tumor toxicity of these drugs by enhancing the redox activation of Fe(III)-thiosemicarbazones and the generation of reactive oxygen species such as HO.","Redox activation of Fe(III)-thiosemicarbazones and Fe(III)-bleomycin by thioredoxin reductase: specificity of enzymatic redox centers and analysis of reactive species formation by ESR spin trapping Abs: Thiosemicarbazones such as Triapine (Tp) and Dp44mT are tridentate iron (Fe) chelators that have well-documented antineoplastic activity. Although Fe-thiosemicarbazones can undergo redox cycling to generate reactive species that may have important roles in their cytotoxicity, there is only limited insight into specific cellular agents that can rapidly reduce Fe(III)-thiosemicarbazones and thereby promote their redox activity. Here we report that thioredoxin reductase-1 (TrxR1) and glutathione reductase (GR) have this activity and that there is considerable specificity to the interactions between specific redox centers in these enzymes and various Fe(III) complexes. Site-directed variants of TrxR1 demonstrate that the selenocysteine (Sec) of the enzyme is not required, whereas the C59 residue and the flavin have important roles. Although TrxR1 and GR have analogous C59/flavin motifs, TrxR is considerably faster than GR. For both enzymes, Fe(III)(Tp)2 is reduced faster than Fe(III)(Dp44mT)2. This reduction promotes redox cycling and the generation of hydroxyl radical (HO) in a peroxide-dependent manner, even with low-micromolar levels of Fe(Tp)2. TrxR also reduces Fe(III)-bleomycin and this activity is Sec-dependent. TrxR cannot reduce Fe(III)-EDTA at significant rates. Our findings are the first to demonstrate pro-oxidant reductive activation of Fe(III)-based antitumor thiosemicarbazones by interactions with specific enzyme species. The marked elevation of TrxR1 in many tumors could contribute to the selective tumor toxicity of these drugs by enhancing the redox activation of Fe(III)-thiosemicarbazones and the generation of reactive oxygen species such as HO."
1786373,Mukherjee et al. 2013,Chromium removal technologies,,Chromium removal technologies Abs: 
1786372,Mukherjee et al. 2013,Combination of best promoter and catalyst for hypervalent chromium oxidation of l-sorbose to lactone of C5 aldonic acid in aqueous media at room temperature,,Combination of best promoter and catalyst for hypervalent chromium oxidation of l-sorbose to lactone of C5 aldonic acid in aqueous media at room temperature Abs: 
1786370,Mirov et al. 2013,Frontiers of mid-infrared lasers based on transition metal doped II–VI semiconductors,,Frontiers of mid-infrared lasers based on transition metal doped II–VI semiconductors Abs: 
1786369,Mateescu et al. 2013,"pH-Specific synthesis, spectroscopic, structural and magnetic, and aqueous solution studies in the binary Cr(III)–quinato system","Chromium is widespread in the environment and is used in ample industrial applications in abiotic and biological systems. Its ability to influence biological processes through interactions with biomolecules underscores its positive role as well as its toxic manifestations in higher organisms. In an attempt to understand its (bio)chemistry, research efforts were undertaken to explore the aqueous chemistry of Cr(III) with the low molecular mass physiological ligand, quinic acid, pH-Specific synthesis in the binary Cr(III)-quinato system led to the isolation of Na[Cr3O(C7H11O6)(6)(H2O)(3)]center dot(NO3)(1.5)center dot(OH)(0.5)center dot 6H(2)O (1). 1 crystallizes in the monoclinic space group C2, with a = 32.16(1) angstrom, b = 14.076(7) angstrom, c = 15.083(5) angstrom, beta = 95.53(1)degrees, V = 6796(5) angstrom(3), and Z = 4. The structure of 1 reveals a trinuclear assembly of Cr(III) with quinate. The assembly consists of a [Cr3O] core containing a triply bound oxido O2- ligand holding the three Cr(III) ions together and six coordinated quinato ligands linking contiguously the three Cr(III) centers in a peripheral cyclic fashion. Each ligand binds two abutting Cr(III) metal ions through the carboxylato oxygens. The alcoholic groups of the quinates are not deprotonated and do not coordinate to the Cr(III) ions. The collective binding of Cr(III) with quinates in a 1:2 ratio leads to a distorted octahedral geometry around each metal center, with the sixth coordination site occupied by a water ligand. 1 was characterized by elemental analysis, spectroscopic (UV-Vis, FT-IR, ESI-MS, EPR), structural, thermal, cyclic voltammetric, and magnetic susceptibility studies. The collective structural and spectroscopic techniques point out the distinct properties of 1 in the solid state and in solution, thus exemplifying the physicochemical profile of that compound in the overall structural speciation scheme of the binary Cr(III)-quinato system. Solid state-solution structural correlation suggests retention of the trinuclear core complex of I in solution, also supported by ESI-MS, thereby lending credence to the detailed aqueous speciation studies in the binary Cr(III)-quinato system investigated in the employed pH range. The unique behavior of 1 in comparison to other known trinuclear [Cr3O]-containing compounds (a) signifies the importance of binary interactions of Cr(III) with hydroxycarboxylic acids, and (b) necessitates further perusal of analogous binary systems of Cr(III), that will enable understanding of the factors influencing the role of the specific metal ion in the development of (bio)chemical reactivity in biological systems and abiotic materials applications. (C) 2012 Elsevier Ltd. All rights reserved.","pH-Specific synthesis, spectroscopic, structural and magnetic, and aqueous solution studies in the binary Cr(III)–quinato system Abs: Chromium is widespread in the environment and is used in ample industrial applications in abiotic and biological systems. Its ability to influence biological processes through interactions with biomolecules underscores its positive role as well as its toxic manifestations in higher organisms. In an attempt to understand its (bio)chemistry, research efforts were undertaken to explore the aqueous chemistry of Cr(III) with the low molecular mass physiological ligand, quinic acid, pH-Specific synthesis in the binary Cr(III)-quinato system led to the isolation of Na[Cr3O(C7H11O6)(6)(H2O)(3)]center dot(NO3)(1.5)center dot(OH)(0.5)center dot 6H(2)O (1). 1 crystallizes in the monoclinic space group C2, with a = 32.16(1) angstrom, b = 14.076(7) angstrom, c = 15.083(5) angstrom, beta = 95.53(1)degrees, V = 6796(5) angstrom(3), and Z = 4. The structure of 1 reveals a trinuclear assembly of Cr(III) with quinate. The assembly consists of a [Cr3O] core containing a triply bound oxido O2- ligand holding the three Cr(III) ions together and six coordinated quinato ligands linking contiguously the three Cr(III) centers in a peripheral cyclic fashion. Each ligand binds two abutting Cr(III) metal ions through the carboxylato oxygens. The alcoholic groups of the quinates are not deprotonated and do not coordinate to the Cr(III) ions. The collective binding of Cr(III) with quinates in a 1:2 ratio leads to a distorted octahedral geometry around each metal center, with the sixth coordination site occupied by a water ligand. 1 was characterized by elemental analysis, spectroscopic (UV-Vis, FT-IR, ESI-MS, EPR), structural, thermal, cyclic voltammetric, and magnetic susceptibility studies. The collective structural and spectroscopic techniques point out the distinct properties of 1 in the solid state and in solution, thus exemplifying the physicochemical profile of that compound in the overall structural speciation scheme of the binary Cr(III)-quinato system. Solid state-solution structural correlation suggests retention of the trinuclear core complex of I in solution, also supported by ESI-MS, thereby lending credence to the detailed aqueous speciation studies in the binary Cr(III)-quinato system investigated in the employed pH range. The unique behavior of 1 in comparison to other known trinuclear [Cr3O]-containing compounds (a) signifies the importance of binary interactions of Cr(III) with hydroxycarboxylic acids, and (b) necessitates further perusal of analogous binary systems of Cr(III), that will enable understanding of the factors influencing the role of the specific metal ion in the development of (bio)chemical reactivity in biological systems and abiotic materials applications. (C) 2012 Elsevier Ltd. All rights reserved."
1786368,Martí et al. 2013,"Ecotoxicity of Cr, Cd, and Pb on two Mediterranean soils","Three potentially toxic elements [chromium (Cr), lead (Pb), and cadmium (Cd)] were tested to assess their effects on two soils of different properties and origin. The soils were a granitic soil (Haplic Arenosol), which meets the requirements of OECD ecotoxicity testing, and a calcareous soil (Calcaric Regosol) with properties often found in the Mediterranean areas. The metal concentrations used ranged from 0.001 to 5,000 mg kg(-1) soil. The effects on soil microbial activity and community composition (respirometry and polymerase chain reaction-denaturing gradient gel electrophoresis analysis), as well as the effects on plant germination and elongation (Lactuca sativa), were assessed. The toxicity of the soil water extracts was also evaluated by the growth inhibition of algal populations (Pseudokirschneriella subcapitata). Cr showed the highest level of toxicity to soil organisms in the assays performed because this element remains in soil as anionic form and is less retained by the soil solid matrix than Cd and Pb. The lowest observed-adverse effect level for Cr ranged from approximately 0.1 mg kg(-1) [substrate induced respiration (SIR) test for the granitic soil] to 10 mg kg(-1) (basal respiration and SIR tests for the calcareous soil). For Pb (SIR) and Cd (SIR and alga tests), these levels were approximately 100 mg kg(-1). Germination and algal tests showed higher sensitivity in Regosol soil than in Arenosol soil for Cr due to differences in the bioavailability between the soils. In the cases or areas where alkaline soils are abundant, these should also be considered in laboratory ecotoxicity testing to avoid underestimation of ecotoxicological risks.","Ecotoxicity of Cr, Cd, and Pb on two Mediterranean soils Abs: Three potentially toxic elements [chromium (Cr), lead (Pb), and cadmium (Cd)] were tested to assess their effects on two soils of different properties and origin. The soils were a granitic soil (Haplic Arenosol), which meets the requirements of OECD ecotoxicity testing, and a calcareous soil (Calcaric Regosol) with properties often found in the Mediterranean areas. The metal concentrations used ranged from 0.001 to 5,000 mg kg(-1) soil. The effects on soil microbial activity and community composition (respirometry and polymerase chain reaction-denaturing gradient gel electrophoresis analysis), as well as the effects on plant germination and elongation (Lactuca sativa), were assessed. The toxicity of the soil water extracts was also evaluated by the growth inhibition of algal populations (Pseudokirschneriella subcapitata). Cr showed the highest level of toxicity to soil organisms in the assays performed because this element remains in soil as anionic form and is less retained by the soil solid matrix than Cd and Pb. The lowest observed-adverse effect level for Cr ranged from approximately 0.1 mg kg(-1) [substrate induced respiration (SIR) test for the granitic soil] to 10 mg kg(-1) (basal respiration and SIR tests for the calcareous soil). For Pb (SIR) and Cd (SIR and alga tests), these levels were approximately 100 mg kg(-1). Germination and algal tests showed higher sensitivity in Regosol soil than in Arenosol soil for Cr due to differences in the bioavailability between the soils. In the cases or areas where alkaline soils are abundant, these should also be considered in laboratory ecotoxicity testing to avoid underestimation of ecotoxicological risks."
1786367,Malherbe and  Claverie 2013,Toward chromium speciation in solids using wavelength dispersive X-ray fluorescence spectrometry Cr K? lines,"The determination of chromium speciation in solid samples is critical for environmental and industrial purposes. Several analytical methods exist to perform such a determination either directly in solid state or liquid state after an extraction step, each of them having some limitations. In this study, the use of a high-resolution wavelength-dispersive X-ray fluorescence spectrometer to determine and quantify chromium species is investigated by looking at the differences in the K? transition profiles between Cr(0), Cr(III) and Cr(VI) compounds. Three different approaches were tested and compared to determine the Cr(VI) fraction of known mixtures: relative height and peak fitting using calibration mixtures, partial least square regression (PLS) of pure compounds, and principal component regression (PCR) of pure compounds. The accuracy of these methods was found to be about the same with an average relative error in the range of 15%. However, PLS and PCR can be easily implemented in an automated way contrary to peak fitting which can be sometimes perceived as analyst-dependant. Another advantage of using PLS and PCR is that information concerning the other oxidation states present in the sample can be retrieved. Finally, PLS and the peak height approach can be used up to 0.5% total chromium which make the XRF an alternative technique to X-ray induced photoelectron spectroscopy (XPS) for chromium speciation in solid state.","Toward chromium speciation in solids using wavelength dispersive X-ray fluorescence spectrometry Cr K? lines Abs: The determination of chromium speciation in solid samples is critical for environmental and industrial purposes. Several analytical methods exist to perform such a determination either directly in solid state or liquid state after an extraction step, each of them having some limitations. In this study, the use of a high-resolution wavelength-dispersive X-ray fluorescence spectrometer to determine and quantify chromium species is investigated by looking at the differences in the K? transition profiles between Cr(0), Cr(III) and Cr(VI) compounds. Three different approaches were tested and compared to determine the Cr(VI) fraction of known mixtures: relative height and peak fitting using calibration mixtures, partial least square regression (PLS) of pure compounds, and principal component regression (PCR) of pure compounds. The accuracy of these methods was found to be about the same with an average relative error in the range of 15%. However, PLS and PCR can be easily implemented in an automated way contrary to peak fitting which can be sometimes perceived as analyst-dependant. Another advantage of using PLS and PCR is that information concerning the other oxidation states present in the sample can be retrieved. Finally, PLS and the peak height approach can be used up to 0.5% total chromium which make the XRF an alternative technique to X-ray induced photoelectron spectroscopy (XPS) for chromium speciation in solid state."
1786366,Majeed et al. 2013,Kinetic modeling: dependence of structural and sorption properties of ZnO—crucial role of synthesis,,Kinetic modeling: dependence of structural and sorption properties of ZnO—crucial role of synthesis Abs: 
1786365,Maity et al. 2013,"Evaluation of remediation process with soapberry derived saponin for removal of heavy metals from contaminated soils in Hai-Pu, Taiwan",,"Evaluation of remediation process with soapberry derived saponin for removal of heavy metals from contaminated soils in Hai-Pu, Taiwan Abs: "
1786364,Lutfullah et al. 2013,Solid phase extraction and determination of Cr(III) by spectrophotometry using cefaclor as a complexing reagent and FAAS,"The present study reports on the application of modified groundnut shell as a new, easily prepared, and stable sorbent for the extraction of trace amount of Cr(III) in aqueous solution. 2-Hydroxybenzaldiminoglycine was immobilized on groundnut shells in alkaline medium and then used as a solid phase for the column preconcentration of Cr(III). The elution was carried out with 3 mL of 2 mol?L(-1) HCl. The amount of eluted Cr(III) was determined by spectrophotometry using cefaclor as a complexing reagent and by flame atomic absorption spectrometry (FAAS). Different experimental variables such as pH, amount of solid sorbent, volume and concentration of eluent, sample and eluent flow rate, and interference of other metal ions on the retention of Cr(III) were studied. Under the optimized conditions, the calibration curves were found to be linear over the concentration range of 13-104 and 10-75 ?g?L(-1) with a detection limit of 3.64 and 1.24 ?g?L(-1) for spectrophotometric method and FAAS, respectively. An enrichment factor of 200 and RSD of ±1.19-1.49 % for five successive determinations of 25 ?g?L(-1) were achieved. The column preconcentration was successfully applied to the analysis of tap water and underground water samples.","Solid phase extraction and determination of Cr(III) by spectrophotometry using cefaclor as a complexing reagent and FAAS Abs: The present study reports on the application of modified groundnut shell as a new, easily prepared, and stable sorbent for the extraction of trace amount of Cr(III) in aqueous solution. 2-Hydroxybenzaldiminoglycine was immobilized on groundnut shells in alkaline medium and then used as a solid phase for the column preconcentration of Cr(III). The elution was carried out with 3 mL of 2 mol?L(-1) HCl. The amount of eluted Cr(III) was determined by spectrophotometry using cefaclor as a complexing reagent and by flame atomic absorption spectrometry (FAAS). Different experimental variables such as pH, amount of solid sorbent, volume and concentration of eluent, sample and eluent flow rate, and interference of other metal ions on the retention of Cr(III) were studied. Under the optimized conditions, the calibration curves were found to be linear over the concentration range of 13-104 and 10-75 ?g?L(-1) with a detection limit of 3.64 and 1.24 ?g?L(-1) for spectrophotometric method and FAAS, respectively. An enrichment factor of 200 and RSD of ±1.19-1.49 % for five successive determinations of 25 ?g?L(-1) were achieved. The column preconcentration was successfully applied to the analysis of tap water and underground water samples."
1786363,Liu and  Wang 2013,Colorimetric speciation of Cr(iii) and Cr(vi) with a gold nanoparticle probe,,Colorimetric speciation of Cr(iii) and Cr(vi) with a gold nanoparticle probe Abs: 
1786362,Li et al. 2013,Optimization of Cr(VI) bioremediation in contaminated soil using indigenous bacteria,,Optimization of Cr(VI) bioremediation in contaminated soil using indigenous bacteria Abs: 
1786361,Li et al. 2013,"The characteristics of nitrate removal by the psychrotolerant denitrifying bacterium Acinetobacter johnonii DBP-3, isolated from a low-temperature eutrophic body of water",,"The characteristics of nitrate removal by the psychrotolerant denitrifying bacterium Acinetobacter johnonii DBP-3, isolated from a low-temperature eutrophic body of water Abs: "
1786360,Li et al. 2013,Adsorbent for chromium removal based on graphene oxide functionalized with magnetic cyclodextrin-chitosan,"A simple chemical bonding method to synthesize magnetic cyclodextrin-chitosan/graphene oxide (CCGO) was reported. The adsorption behaviors of Cr(VI) in aqueous solution on CCGO were systematically investigated. As the results shown that, with the advantage of high surface area, abundant hydroxyl and amino groups of CCGO, and the magnetic property of Fe3O4, the Cr(VI) can be easily and rapidly extracted from the water by magnetic attraction under investigation. The adsorption equilibrium of CCGO for Cr(VI) corresponded with Langmuir isotherm, and the novel adsorbent exhibited better Cr(VI) removal efficiency in solutions with low pH. It was found that the Cr(VI) adsorption performance of CCGO strongly depends on their surface charge concentration and specific surface area. These results provide evidences for estimating and optimizing the removal of metal ions from the wastewater by using of CCGO composites in the future.","Adsorbent for chromium removal based on graphene oxide functionalized with magnetic cyclodextrin-chitosan Abs: A simple chemical bonding method to synthesize magnetic cyclodextrin-chitosan/graphene oxide (CCGO) was reported. The adsorption behaviors of Cr(VI) in aqueous solution on CCGO were systematically investigated. As the results shown that, with the advantage of high surface area, abundant hydroxyl and amino groups of CCGO, and the magnetic property of Fe3O4, the Cr(VI) can be easily and rapidly extracted from the water by magnetic attraction under investigation. The adsorption equilibrium of CCGO for Cr(VI) corresponded with Langmuir isotherm, and the novel adsorbent exhibited better Cr(VI) removal efficiency in solutions with low pH. It was found that the Cr(VI) adsorption performance of CCGO strongly depends on their surface charge concentration and specific surface area. These results provide evidences for estimating and optimizing the removal of metal ions from the wastewater by using of CCGO composites in the future."
1786359,Colin et al. 2013,Production and partial characterization of bioemulsifier from a chromium-resistant actinobacteria,"Surface-active compounds such as synthetic emulsifiers have been used for several decades, both for the degradation of hydrocarbons and increasing desorption of soil-bound metals. However, due to their high toxicity, low degradability, and production costs unaffordable for use in larger ecosystems, synthetic emulsifiers have been gradually replaced by those derived from natural sources such as plants or microbes. In previous studies, the bacterium Streptomyces sp. MC1 has shown the ability to reduce and/or accumulate Cr(VI), a highly promising advance in the development of methods for environmental clean-up of sites contaminated with chromium. Here, new studies on the production of emulsifier from this strain are presented. The cultivation factors that have a significant influence on emulsifier biosynthesis, as well as the interactions among them, were studied by factorial design. Based upon optimization studies, maximum bioemulsifier production was detected in the culture medium having an initial pH of 8 with phosphate 2.0 g L(-1) and Ca(+2) 1.0 g L(-1) added, with an emulsification index about 3.5 times greater compared to the basal value. Interestingly, in the presence of 5.0 g L(-1) Cr(VI), Streptomyces sp. MC1 retained about 65% of its emulsifier production ability. Partially purified emulsifier presented high thermo-stability and partial water solubility. These findings could have promising future prospects for the remediation of organic- and metal-contaminated sites.","Production and partial characterization of bioemulsifier from a chromium-resistant actinobacteria Abs: Surface-active compounds such as synthetic emulsifiers have been used for several decades, both for the degradation of hydrocarbons and increasing desorption of soil-bound metals. However, due to their high toxicity, low degradability, and production costs unaffordable for use in larger ecosystems, synthetic emulsifiers have been gradually replaced by those derived from natural sources such as plants or microbes. In previous studies, the bacterium Streptomyces sp. MC1 has shown the ability to reduce and/or accumulate Cr(VI), a highly promising advance in the development of methods for environmental clean-up of sites contaminated with chromium. Here, new studies on the production of emulsifier from this strain are presented. The cultivation factors that have a significant influence on emulsifier biosynthesis, as well as the interactions among them, were studied by factorial design. Based upon optimization studies, maximum bioemulsifier production was detected in the culture medium having an initial pH of 8 with phosphate 2.0 g L(-1) and Ca(+2) 1.0 g L(-1) added, with an emulsification index about 3.5 times greater compared to the basal value. Interestingly, in the presence of 5.0 g L(-1) Cr(VI), Streptomyces sp. MC1 retained about 65% of its emulsifier production ability. Partially purified emulsifier presented high thermo-stability and partial water solubility. These findings could have promising future prospects for the remediation of organic- and metal-contaminated sites."
1786358,La?njevac et al. 2013,Ti substrate coated with composite Cr–MoO2 coatings as highly selective cathode materials in hypochlorite production,,Ti substrate coated with composite Cr–MoO2 coatings as highly selective cathode materials in hypochlorite production Abs: 
1786357,Kumar et al. 2013,Lipoic acid prevents Cr(6+) induced cell transformation and the associated genomic dysregulation,"Investigation of the transcription profile of cells transformed by Cr(6+) in vivo was undertaken. The objective was to elucidate genomic changes underlying the mechanism of action of the carcinogenic dose of Cr(6+)and their prevention using metabolic antioxidant lipoic acid (LA). Cr(6+) was administered intraperitoneally to LPS+TPA challenged Swiss albino mice in host mediated cell transformation assay using peritoneal macrophages in vivo. The cell transforming potential of Cr(6+) test doses was validated by gain of anchorage independent growth potential in soft agar and loss of Fc receptor on target cells. LA was administered in equimolar doses. Compared to non-transformed cells, the gene expression profile of transformed cells was found to be dysregulated substantially and in dose dependent manner. Genes showing down regulation were found to be involved in tumour suppression, apoptosis, DNA repair, and cell-cycle. A similar response was noted in the genes pertaining to immune system, morphogenesis, cell-communication, energy-metabolism, and biosynthesis. The co-administration of lipoic acid prevented the transcription dysregulation and cell transformation by Cr(6+) in vivo. The influenced pathways seem to be crucial for progression as well as mitigation of Cr toxicity; and their response to LA indicated their critical role in mechanism of anti-carcinogenic action of LA. Results are of importance to mitigate Cr(6+) induced occupational cancer hazard.","Lipoic acid prevents Cr(6+) induced cell transformation and the associated genomic dysregulation Abs: Investigation of the transcription profile of cells transformed by Cr(6+) in vivo was undertaken. The objective was to elucidate genomic changes underlying the mechanism of action of the carcinogenic dose of Cr(6+)and their prevention using metabolic antioxidant lipoic acid (LA). Cr(6+) was administered intraperitoneally to LPS+TPA challenged Swiss albino mice in host mediated cell transformation assay using peritoneal macrophages in vivo. The cell transforming potential of Cr(6+) test doses was validated by gain of anchorage independent growth potential in soft agar and loss of Fc receptor on target cells. LA was administered in equimolar doses. Compared to non-transformed cells, the gene expression profile of transformed cells was found to be dysregulated substantially and in dose dependent manner. Genes showing down regulation were found to be involved in tumour suppression, apoptosis, DNA repair, and cell-cycle. A similar response was noted in the genes pertaining to immune system, morphogenesis, cell-communication, energy-metabolism, and biosynthesis. The co-administration of lipoic acid prevented the transcription dysregulation and cell transformation by Cr(6+) in vivo. The influenced pathways seem to be crucial for progression as well as mitigation of Cr toxicity; and their response to LA indicated their critical role in mechanism of anti-carcinogenic action of LA. Results are of importance to mitigate Cr(6+) induced occupational cancer hazard."
1786356,Kumar et al. 2013,Development of Chromium(III) Selective Potentiometric Sensor by Using Synthesized Triazole Derivative as an Ionophore,,Development of Chromium(III) Selective Potentiometric Sensor by Using Synthesized Triazole Derivative as an Ionophore Abs: 
1786355,Kumar and  Sharma 2013,Development of all solid state chromium(III) selective sensor by using newly synthesized triazole derivative as an ionophore in PVC matrix,,Development of all solid state chromium(III) selective sensor by using newly synthesized triazole derivative as an ionophore in PVC matrix Abs: 
1786354,Kumar et al. 2013,Biochemical Changes of Fresh Water Cyanobacteria Dolichospermum flos-aquae NTMS07 to Chromium-Induced Stress with Special Reference to Antioxidant Enzymes and Cellular Fatty Acids,"This investigation examined the efficiency of Dolichospermum flos-aquae NTMS07 in the removal of Cr(VI) from exposure water at various concentrations (2.5, 5, 7.5, 10 mg/L) over different time intervals of contact (1-5 days). Chromium removal was maximum at 2.5 mg/L, and decreased with increased concentration. The responses of the antioxidative enzymes superoxide dismutase (SOD) and catalase (CAT) were measured, and the composition of fatty acids was evaluated at a concentration of 5 mg Cr/L. Significant increases in the activity levels of SOD and CAT were obtained. The level of total unsaturated fatty acids decreased with exposure to Cr. It is proposed that the observed decrease in total unsaturated fatty acid level is a defense mechanism against Cr-induced oxidative stress and cell membrane damage.","Biochemical Changes of Fresh Water Cyanobacteria Dolichospermum flos-aquae NTMS07 to Chromium-Induced Stress with Special Reference to Antioxidant Enzymes and Cellular Fatty Acids Abs: This investigation examined the efficiency of Dolichospermum flos-aquae NTMS07 in the removal of Cr(VI) from exposure water at various concentrations (2.5, 5, 7.5, 10 mg/L) over different time intervals of contact (1-5 days). Chromium removal was maximum at 2.5 mg/L, and decreased with increased concentration. The responses of the antioxidative enzymes superoxide dismutase (SOD) and catalase (CAT) were measured, and the composition of fatty acids was evaluated at a concentration of 5 mg Cr/L. Significant increases in the activity levels of SOD and CAT were obtained. The level of total unsaturated fatty acids decreased with exposure to Cr. It is proposed that the observed decrease in total unsaturated fatty acid level is a defense mechanism against Cr-induced oxidative stress and cell membrane damage."
1786353,Kumar and  Rajesh 2013,"Exploring the interesting interaction between graphene oxide, Aliquat-336 (a room temperature ionic liquid) and chromium(vi) for wastewater treatment",,"Exploring the interesting interaction between graphene oxide, Aliquat-336 (a room temperature ionic liquid) and chromium(vi) for wastewater treatment Abs: "
1786352,Kumar et al. 2013,Effect of the Protonation and Chemical Doping of Poly(o-toludine) with Copper Sulfate on the Spectral and Electrical Properties of the Host Polymer,,Effect of the Protonation and Chemical Doping of Poly(o-toludine) with Copper Sulfate on the Spectral and Electrical Properties of the Host Polymer Abs: 
1786351,Khorsandi and  Rabbani-Chadegani 2013,Studies on the genotoxic effect of chromium oxide (Cr VI): interaction with deoxyribonucleic acid in solution,"Chromium is a toxic and carcinogenic compound widely distributed in environment. In the present study we have investigated the interaction of chromium oxide with DNA employing UV/vis and fluorescence spectroscopy as well as Circular dichroism, thermal denaturation, retardation polyacrylamide gel electrophoresis and DNA-cellulose affinity techniques. The results showed that the binding of chromium oxide to DNA is concentration dependent; at low concentration shows a little effect but ant higher concentrations (&gt;100?g/ml) reduced the absorbance at 260 and 210nm producing hypochromicity. Also ?(max) of the metal at 210, 260 and 350nm was reduced. DNA chromophores quenched with the chromium oxide and decreased fluorescence emission intensity. Upon binding of the metal to DNA the elliplicity at positive extreme was decreased (275nm) and increased the ellipticity of the DNA at negative extreme 245nm. Thermal denaturation profile of DNA shifted to higher degrees upon chromium oxide binding which accompanied by hypochromicity. Also, affinity of chromium oxide to double stranded DNA was higher than single stranded DNA. From the result it is concluded that chromium oxide interacts with DNA via two modes of interaction inducing structural changes and DNA compaction evidence providing chromium oxide genotoxicity.","Studies on the genotoxic effect of chromium oxide (Cr VI): interaction with deoxyribonucleic acid in solution Abs: Chromium is a toxic and carcinogenic compound widely distributed in environment. In the present study we have investigated the interaction of chromium oxide with DNA employing UV/vis and fluorescence spectroscopy as well as Circular dichroism, thermal denaturation, retardation polyacrylamide gel electrophoresis and DNA-cellulose affinity techniques. The results showed that the binding of chromium oxide to DNA is concentration dependent; at low concentration shows a little effect but ant higher concentrations (&gt;100?g/ml) reduced the absorbance at 260 and 210nm producing hypochromicity. Also ?(max) of the metal at 210, 260 and 350nm was reduced. DNA chromophores quenched with the chromium oxide and decreased fluorescence emission intensity. Upon binding of the metal to DNA the elliplicity at positive extreme was decreased (275nm) and increased the ellipticity of the DNA at negative extreme 245nm. Thermal denaturation profile of DNA shifted to higher degrees upon chromium oxide binding which accompanied by hypochromicity. Also, affinity of chromium oxide to double stranded DNA was higher than single stranded DNA. From the result it is concluded that chromium oxide interacts with DNA via two modes of interaction inducing structural changes and DNA compaction evidence providing chromium oxide genotoxicity."
1786350,Khan et al. 2013,Toxic effects of chromium on tannery workers at Sialkot (Pakistan),"Chromium is widely used in the leather industry, and tannery workers are under constant threat of adverse health effects due to its excessive exposure. Our objective was to find out the toxic effects of chromium on tannery workers at Sialkot, Pakistan. A total of 240 males consisting of 120 workers from tanneries at Sialkot and equal number of controls were included. Blood complete counts, high-sensitive C-reactive protein, malondialdehyde and routine biochemical tests were carried out by routine procedures. Chromium levels in blood (BCr) and urine were analyzed using graphite furnace atomic absorption spectrophotometer Perkin Elmer analyst-200. Results revealed that all the workers were male with average age of 33 years and 15 (13%) had skin rashes, 14 (12%) had chronic bronchitis, 10 (8%) had gastritis and 4 (3%) conjunctivitis. The tannery workers had significantly raised median (interquartile range) of BCr 569 (377-726) nmol/L as compared to 318 (245-397) nmol/L in the control (p < 0.001). Sixty-five (54%) workers had BCr levels above the upper limit set by Agency for Toxic Substance and Drug Registry. The urinary chromium excretion was significantly high in workers 131 (46-312) nmol/L as compared to 13 (3-26) nmol/L in controls (p < 0.01). The workers had hematological, hepatic and renal function impairment because of oxidative stress on body systems. It is concluded that about half of the workers had excessive exposure to chromium in the tanneries at Sialkot. They had significantly raised chromium levels in their biological fluids and adverse health effects due to enhanced oxidative stress and inflammatory changes.","Toxic effects of chromium on tannery workers at Sialkot (Pakistan) Abs: Chromium is widely used in the leather industry, and tannery workers are under constant threat of adverse health effects due to its excessive exposure. Our objective was to find out the toxic effects of chromium on tannery workers at Sialkot, Pakistan. A total of 240 males consisting of 120 workers from tanneries at Sialkot and equal number of controls were included. Blood complete counts, high-sensitive C-reactive protein, malondialdehyde and routine biochemical tests were carried out by routine procedures. Chromium levels in blood (BCr) and urine were analyzed using graphite furnace atomic absorption spectrophotometer Perkin Elmer analyst-200. Results revealed that all the workers were male with average age of 33 years and 15 (13%) had skin rashes, 14 (12%) had chronic bronchitis, 10 (8%) had gastritis and 4 (3%) conjunctivitis. The tannery workers had significantly raised median (interquartile range) of BCr 569 (377-726) nmol/L as compared to 318 (245-397) nmol/L in the control (p < 0.001). Sixty-five (54%) workers had BCr levels above the upper limit set by Agency for Toxic Substance and Drug Registry. The urinary chromium excretion was significantly high in workers 131 (46-312) nmol/L as compared to 13 (3-26) nmol/L in controls (p < 0.01). The workers had hematological, hepatic and renal function impairment because of oxidative stress on body systems. It is concluded that about half of the workers had excessive exposure to chromium in the tanneries at Sialkot. They had significantly raised chromium levels in their biological fluids and adverse health effects due to enhanced oxidative stress and inflammatory changes."
1786349,Kelepertzis et al. 2013,"Origin, mineral speciation and geochemical baseline mapping of Ni and Cr in agricultural topsoils of Thiva Valley (central Greece)",,"Origin, mineral speciation and geochemical baseline mapping of Ni and Cr in agricultural topsoils of Thiva Valley (central Greece) Abs: "
1786348,Kaushik and  Malik 2013,Comparative performance evaluation of Aspergillus lentulus for dye removal through bioaccumulation and biosorption,"Dyes used in various industries are discharged into the environment and pose major environmental concern. In the present study, fungal isolate Aspergillus lentulus was utilized for the treatment of various dyes, dye mixtures and dye containing effluent in dual modes, bioaccumulation (employing growing biomass) and biosorption (employing pre-cultivated biomass). The effect of dye toxicity on the growth of the fungal isolate was studied through phase contrast and scanning electron microscopy. Dye biosorption was studied using first and second-order kinetic models. Effects of factors influencing adsorption and isotherm studies were also conducted. During bioaccumulation, good removal was obtained for anionic dyes (100 mg/l), viz. Acid Navy Blue, Fast Red A and Orange-HF dye (99.4 %, 98.8 % and 98.7 %, respectively) in 48 h. Cationic dyes (10 mg/l), viz. Rhodamine B and Methylene Blue, had low removal efficiency (80.3 % [48 h] and 92.7 % [144 h], respectively) as compared to anionic dyes. In addition to this, fungal isolate showed toxicity response towards Methylene Blue by producing larger aggregates of fungal pellets. To overcome the limitations of bioaccumulation, dye removal in biosorption mode was studied. In this mode, significant removal was observed for anionic (96.7-94.3 %) and cationic (35.4-90.9 %) dyes in 24 h. The removal of three anionic dyes and Rhodamine B followed first-order kinetic model whereas removal of Methylene Blue followed second-order kinetic model. Overall, fungal isolate could remove more than 90 % dye from different dye mixtures in bioaccumulation mode and more than 70 % dye in biosorption mode. Moreover, significant color removal from handmade paper unit effluent in bioaccumulation mode (86.4 %) as well as in biosorption mode (77.1 %) was obtained within 24 h. This study validates the potential of fungal isolate, A. lentulus, to be used as the primary organism for treating dye containing wastewater.","Comparative performance evaluation of Aspergillus lentulus for dye removal through bioaccumulation and biosorption Abs: Dyes used in various industries are discharged into the environment and pose major environmental concern. In the present study, fungal isolate Aspergillus lentulus was utilized for the treatment of various dyes, dye mixtures and dye containing effluent in dual modes, bioaccumulation (employing growing biomass) and biosorption (employing pre-cultivated biomass). The effect of dye toxicity on the growth of the fungal isolate was studied through phase contrast and scanning electron microscopy. Dye biosorption was studied using first and second-order kinetic models. Effects of factors influencing adsorption and isotherm studies were also conducted. During bioaccumulation, good removal was obtained for anionic dyes (100 mg/l), viz. Acid Navy Blue, Fast Red A and Orange-HF dye (99.4 %, 98.8 % and 98.7 %, respectively) in 48 h. Cationic dyes (10 mg/l), viz. Rhodamine B and Methylene Blue, had low removal efficiency (80.3 % [48 h] and 92.7 % [144 h], respectively) as compared to anionic dyes. In addition to this, fungal isolate showed toxicity response towards Methylene Blue by producing larger aggregates of fungal pellets. To overcome the limitations of bioaccumulation, dye removal in biosorption mode was studied. In this mode, significant removal was observed for anionic (96.7-94.3 %) and cationic (35.4-90.9 %) dyes in 24 h. The removal of three anionic dyes and Rhodamine B followed first-order kinetic model whereas removal of Methylene Blue followed second-order kinetic model. Overall, fungal isolate could remove more than 90 % dye from different dye mixtures in bioaccumulation mode and more than 70 % dye in biosorption mode. Moreover, significant color removal from handmade paper unit effluent in bioaccumulation mode (86.4 %) as well as in biosorption mode (77.1 %) was obtained within 24 h. This study validates the potential of fungal isolate, A. lentulus, to be used as the primary organism for treating dye containing wastewater."
1786347,Kaneko and  Ogawa 2013,Effective concentration of dichromate anions using layered double hydroxides from acidic solutions,,Effective concentration of dichromate anions using layered double hydroxides from acidic solutions Abs: 
1786346,Huang et al. 2013,Removal of chromium(VI) Ions from aqueous solutions with protonated crosslinked chitosan,,Removal of chromium(VI) Ions from aqueous solutions with protonated crosslinked chitosan Abs: 
1786345,Hseu and  Iizuka 2013,Pedogeochemical characteristics of chromite in a paddy soil derived from serpentinites,,Pedogeochemical characteristics of chromite in a paddy soil derived from serpentinites Abs: 
1786344,Holt et al. 2013,Heat-treated polyacrylonitrile nanofibers: A new material for efficient photo-assisted reduction of Cr(VI),,Heat-treated polyacrylonitrile nanofibers: A new material for efficient photo-assisted reduction of Cr(VI) Abs: 
1786343,Handzlik and  Kurleto 2013,Assessment of density functional methods for thermochemistry of chromium oxo compounds and their application in a study of chromia–silica system,,Assessment of density functional methods for thermochemistry of chromium oxo compounds and their application in a study of chromia–silica system Abs: 
1786342,Handzlik et al. 2013,Structure of Monomeric Chromium(VI) Oxide Species Supported on Silica: Periodic and Cluster DFT Studies,,Structure of Monomeric Chromium(VI) Oxide Species Supported on Silica: Periodic and Cluster DFT Studies Abs: 
1786341,Hafuka et al. 2013,BODIPY-Based Ratiometric Fluoroionophores with Bidirectional Spectral Shifts for the Selective Recognition of Heavy Metal Ions,,BODIPY-Based Ratiometric Fluoroionophores with Bidirectional Spectral Shifts for the Selective Recognition of Heavy Metal Ions Abs: 
1786340,Gyepesová and  Langer 2013,"Ca10(Cr(V)O4)6(Cr(VI)O4), a disordered mixed-valence chromium compound exhibiting inversion twinning","The structure analysis of so-called 9CaO·4CrO(3)·Cr(2)O(3) proved it to be the title compound, decacalcium hexakis[chromate(V)] chromate(VI), with the simultaneous presence of unusual chromium oxidation states. The structure determination was carried out on a crystal that had inversion twinning. The Cr(VI)O(4) tetrahedron is situated on a threefold axis and is disordered over two possible orientations that share three O atoms, while the Cr(V)O(4) tetrahedra are in general positions and are ordered. The charge is balanced by Ca(2+) cations, one of which is located on a threefold axis. The Ca(2+) ions are coordinated by six, seven or eight O atoms. The compound is a significant phase in the CaO-CrO(x) system and its formation reduces the refractoriness of calcium-rich compositions in an oxidizing atmosphere.","Ca10(Cr(V)O4)6(Cr(VI)O4), a disordered mixed-valence chromium compound exhibiting inversion twinning Abs: The structure analysis of so-called 9CaO·4CrO(3)·Cr(2)O(3) proved it to be the title compound, decacalcium hexakis[chromate(V)] chromate(VI), with the simultaneous presence of unusual chromium oxidation states. The structure determination was carried out on a crystal that had inversion twinning. The Cr(VI)O(4) tetrahedron is situated on a threefold axis and is disordered over two possible orientations that share three O atoms, while the Cr(V)O(4) tetrahedra are in general positions and are ordered. The charge is balanced by Ca(2+) cations, one of which is located on a threefold axis. The Ca(2+) ions are coordinated by six, seven or eight O atoms. The compound is a significant phase in the CaO-CrO(x) system and its formation reduces the refractoriness of calcium-rich compositions in an oxidizing atmosphere."
1786339,Gupta et al. 2013,Preparation of bio-based porous carbon by microwave assisted phosphoric acid activation and its use for adsorption of Cr(VI),"Ficus carica fiber based activated carbon (FCAC) was used as a potential adsorbent for Cr(VI) removal from aqueous system. The adsorbent was prepared by carbonization of F. carica fiber followed by H3PO4 activation under microwave radiations. The activated carbon was characterized using scanning electron microscopy and Fourier transformer infrared spectroscopy. The adsorption data were well studied for adsorption isotherms, kinetics models, and thermodynamics. Adsorption of chromium ion followed the second-order kinetics and best fitted the Langmuir adsorption isotherms. The maximum adsorption capacity of Cr(VI) onto FCAC was 44.84 mg/g. The calculated values of thermodynamic parameters like enthalpy change (?H°), entropy change (?S°), and free energy change (?G°) were found to be 7.85 kJ/mol, 69.17 J/mol K, and -13.11 kJ/mol, respectively. Adsorption process was spontaneous and endothermic in nature.","Preparation of bio-based porous carbon by microwave assisted phosphoric acid activation and its use for adsorption of Cr(VI) Abs: Ficus carica fiber based activated carbon (FCAC) was used as a potential adsorbent for Cr(VI) removal from aqueous system. The adsorbent was prepared by carbonization of F. carica fiber followed by H3PO4 activation under microwave radiations. The activated carbon was characterized using scanning electron microscopy and Fourier transformer infrared spectroscopy. The adsorption data were well studied for adsorption isotherms, kinetics models, and thermodynamics. Adsorption of chromium ion followed the second-order kinetics and best fitted the Langmuir adsorption isotherms. The maximum adsorption capacity of Cr(VI) onto FCAC was 44.84 mg/g. The calculated values of thermodynamic parameters like enthalpy change (?H°), entropy change (?S°), and free energy change (?G°) were found to be 7.85 kJ/mol, 69.17 J/mol K, and -13.11 kJ/mol, respectively. Adsorption process was spontaneous and endothermic in nature."
1786338,Gupta et al. 2013,Remediation of noxious chromium (VI) utilizing acrylic acid grafted lignocellulosic adsorbent,,Remediation of noxious chromium (VI) utilizing acrylic acid grafted lignocellulosic adsorbent Abs: 
1786337,Guerra et al. 2013,"Adsorption of mercury from aqueous solution by nontronite, Aspergillus niger, and hybrid material",,"Adsorption of mercury from aqueous solution by nontronite, Aspergillus niger, and hybrid material Abs: "
1786336,Guerra et al. 2013,Kinetics and thermodynamics of Cr(VI) ion adsorption onto organo-bentonite from the Amazon region,,Kinetics and thermodynamics of Cr(VI) ion adsorption onto organo-bentonite from the Amazon region Abs: 
1786335,Ghosh et al. 2013,Selection of Suitable Combination of Nonfunctional Micellar Catalyst and Heteroaromatic Nitrogen Base as Promoter for Chromic Acid Oxidation of Ethanol to Acetaldehyde in Aqueous Medium at Room Temperature,,Selection of Suitable Combination of Nonfunctional Micellar Catalyst and Heteroaromatic Nitrogen Base as Promoter for Chromic Acid Oxidation of Ethanol to Acetaldehyde in Aqueous Medium at Room Temperature Abs: 
1786334,Ge et al. 2013,Effect of structure-directing agents on facile hydrothermal preparation of hierarchical ?-Al2O3 and their adsorption performance toward Cr(VI) and CO2,"Hierarchical flower-like and sphere-like mesoporous ?-Al2O3 microparticles were successfully prepared by a facile hydrothermal method followed by a calcination process using sodium aluminate as aluminum source, urea as precipitating agent, and Pluronic F127 (EO106PO70EO106), polyacrylic acid sodium (PAAS), and mixed F127-PAAS as structure-directing agents (SDAs), respectively. Effects of the SDAs on the phase structure, morphology, textural properties, surface alkaline, and the adsorption performance toward Cr(VI) and CO2 of the as-prepared samples were comparatively studied by X-ray diffraction (XRD), scanning electron microscope (SEM), transmission electron microscope (TEM), N2 adsorption-desorption, CO2 temperature programmed desorption (CO2-TPD), and UV-Vis spectrophotometric method. The results indicate that the sphere-like ?-Al2O3 obtained by using F127 as the SDA shows the best adsorption performance toward Cr(VI) with a high adsorption rate of 95% and adsorption capacity of 5.7 mg/g when the adsorption reaches equilibrium for 4h at room temperature. However, the flower-like ?-Al2O3 obtained by using PAAS as the SDA has the biggest CO2 adsorption capacity of 1.04 mmol/g at room temperature. This work provides a simple and practical way to prepare potentially bifunctional ?-Al2O3 adsorbent for the removal of pollutants in water and air treatment from cheap sodium aluminate by using different SDAs.","Effect of structure-directing agents on facile hydrothermal preparation of hierarchical ?-Al2O3 and their adsorption performance toward Cr(VI) and CO2 Abs: Hierarchical flower-like and sphere-like mesoporous ?-Al2O3 microparticles were successfully prepared by a facile hydrothermal method followed by a calcination process using sodium aluminate as aluminum source, urea as precipitating agent, and Pluronic F127 (EO106PO70EO106), polyacrylic acid sodium (PAAS), and mixed F127-PAAS as structure-directing agents (SDAs), respectively. Effects of the SDAs on the phase structure, morphology, textural properties, surface alkaline, and the adsorption performance toward Cr(VI) and CO2 of the as-prepared samples were comparatively studied by X-ray diffraction (XRD), scanning electron microscope (SEM), transmission electron microscope (TEM), N2 adsorption-desorption, CO2 temperature programmed desorption (CO2-TPD), and UV-Vis spectrophotometric method. The results indicate that the sphere-like ?-Al2O3 obtained by using F127 as the SDA shows the best adsorption performance toward Cr(VI) with a high adsorption rate of 95% and adsorption capacity of 5.7 mg/g when the adsorption reaches equilibrium for 4h at room temperature. However, the flower-like ?-Al2O3 obtained by using PAAS as the SDA has the biggest CO2 adsorption capacity of 1.04 mmol/g at room temperature. This work provides a simple and practical way to prepare potentially bifunctional ?-Al2O3 adsorbent for the removal of pollutants in water and air treatment from cheap sodium aluminate by using different SDAs."
1786333,Garnier et al. 2013,"Cr(VI) genesis and dynamics in Ferralsols developed from ultramafic rocks: The case of Niquelândia, Brazil",,"Cr(VI) genesis and dynamics in Ferralsols developed from ultramafic rocks: The case of Niquelândia, Brazil Abs: "
1786332,Gaborim et al. 2013,Confocal microscopy and femtosecond-based second-harmonic generation characterization of the interaction of chromium ions with environmental surfaces,,Confocal microscopy and femtosecond-based second-harmonic generation characterization of the interaction of chromium ions with environmental surfaces Abs: 
1786331,Frei and  Polat 2013,"Chromium isotope fractionation during oxidative weathering—Implications from the study of a Paleoproterozoic (ca. 1.9Ga) paleosol, Schreiber Beach, Ontario, Canada",,"Chromium isotope fractionation during oxidative weathering—Implications from the study of a Paleoproterozoic (ca. 1.9Ga) paleosol, Schreiber Beach, Ontario, Canada Abs: "
1786330,Frei et al. 2013,Fluctuations in late Neoproterozoic atmospheric oxidation — Cr isotope chemostratigraphy and iron speciation of the late Ediacaran lower Arroyo del Soldado Group (Uruguay),,Fluctuations in late Neoproterozoic atmospheric oxidation — Cr isotope chemostratigraphy and iron speciation of the late Ediacaran lower Arroyo del Soldado Group (Uruguay) Abs: 
1786329,NIOSH 2013,Criteria for a Recommended Standard: Occupational Exposure to Hexavalent Chromium,"In this criteria document, the National Institute for Occupational Safety and Health (NIOSH) reviews the critical health effects studies of hexavalent chromium (Cr(VI)) compounds in order to update its assessment of the potential health effects of occupational exposure to Cr(VI) compounds and its recommendations to prevent and control these workplace exposures. NIOSH reviews the following aspects of workplace exposure to Cr(VI) compounds: the potential for exposures (Chapter 2), analytical methods and considerations (Chapter 3), human health effects (Chapter 4), experimental studies (Chapter 5), and quantitative risk assessments (Chapter 6). Based on evaluation of this information, NIOSH provides recommendations for a revised recommended exposure limit (REL) for Cr(VI) compounds (Chapter 7) and other recommendations for risk management (Chapter 8).","Criteria for a Recommended Standard: Occupational Exposure to Hexavalent Chromium Abs: In this criteria document, the National Institute for Occupational Safety and Health (NIOSH) reviews the critical health effects studies of hexavalent chromium (Cr(VI)) compounds in order to update its assessment of the potential health effects of occupational exposure to Cr(VI) compounds and its recommendations to prevent and control these workplace exposures. NIOSH reviews the following aspects of workplace exposure to Cr(VI) compounds: the potential for exposures (Chapter 2), analytical methods and considerations (Chapter 3), human health effects (Chapter 4), experimental studies (Chapter 5), and quantitative risk assessments (Chapter 6). Based on evaluation of this information, NIOSH provides recommendations for a revised recommended exposure limit (REL) for Cr(VI) compounds (Chapter 7) and other recommendations for risk management (Chapter 8)."
1786328,Fonseca-Correa et al. 2013,Trivalent chromium removal from aqueous solution with physically and chemically modified corncob waste,,Trivalent chromium removal from aqueous solution with physically and chemically modified corncob waste Abs: 
1786327,Fernández-Pazos et al. 2013,Cr(VI) Adsorption and Desorption on Soils and Biosorbents,,Cr(VI) Adsorption and Desorption on Soils and Biosorbents Abs: 
1786326,Fernández et al. 2013,Textile-dye polluted waters as a source for selecting chromate-reducing yeasts through Cr(VI)-enriched microcosms,,Textile-dye polluted waters as a source for selecting chromate-reducing yeasts through Cr(VI)-enriched microcosms Abs: 
1786325,Fabbricino et al. 2013,An environmental friendly cycle for Cr(III) removal and recovery from tannery wastewater,"Results of a lab-scale experimental study are presented that aim to verify the use of ground shrimp shells, not otherwise conditioned, as an adsorbent material to remove chromium(III) from tannery wastewater. The obtained removal efficiency is found to be always over 90%, confirming the capacity of the tested materials to remove chromium(III). The adsorption process is well described by the Brauner-Emmett-Teller isotherm, indicating the existence of both weak and strong adsorption sites inside the shells. Kinetic tests allow to verify that the removal process takes place rapidly during the first 2 h and then tends to reach a plateau: the pseudo second-order model is found to be able to simulate with good approximation, the adsorption process. Analyses comparing the treatment process using shrimp shells vs. other chemical products frequently used for chromium removal, supported by microscopic observations, indicate that the efficiency obtained using shrimp shell is comparable to the efficiency obtained using sodium bicarbonate and sodium hydroxide, but the removal mechanism is different as the adsorption on the polysaccharidic matrix of the shells prevails over the precipitation of chromium salts. The skin tanned with recovered chromium is found to be of low quality; on the contrary satisfying tanning results are obtained using, as tanning agent, the sludge produced by the adsorption process without any further treatment, except for pH correction.","An environmental friendly cycle for Cr(III) removal and recovery from tannery wastewater Abs: Results of a lab-scale experimental study are presented that aim to verify the use of ground shrimp shells, not otherwise conditioned, as an adsorbent material to remove chromium(III) from tannery wastewater. The obtained removal efficiency is found to be always over 90%, confirming the capacity of the tested materials to remove chromium(III). The adsorption process is well described by the Brauner-Emmett-Teller isotherm, indicating the existence of both weak and strong adsorption sites inside the shells. Kinetic tests allow to verify that the removal process takes place rapidly during the first 2 h and then tends to reach a plateau: the pseudo second-order model is found to be able to simulate with good approximation, the adsorption process. Analyses comparing the treatment process using shrimp shells vs. other chemical products frequently used for chromium removal, supported by microscopic observations, indicate that the efficiency obtained using shrimp shell is comparable to the efficiency obtained using sodium bicarbonate and sodium hydroxide, but the removal mechanism is different as the adsorption on the polysaccharidic matrix of the shells prevails over the precipitation of chromium salts. The skin tanned with recovered chromium is found to be of low quality; on the contrary satisfying tanning results are obtained using, as tanning agent, the sludge produced by the adsorption process without any further treatment, except for pH correction."
1786324,Eybe et al. 2013,Determination of oral uptake and biodistribution of platinum and chromium by the garden snail (Helix aspersa) employing nano-secondary ion mass-spectrometry,"Environmental heavy metal contamination is a case of concern for both animal and human health. Studying the fate of metals in plant or animal tissues may provide information on pollution. In the present study, we investigated the possibility to follow the biological fate of chromium and platinum uptake in common garden snails (Helix aspersa), typically accumulating high concentrations of metals from their environment. Chromium and platinum were administered orally to snails in 5 groups (n=25/group): control, food contaminated by ca. 2.5 ?g g(-1) and 19 ?g g(-1) chromium and 2.5 ?g g(-1) and 25 ?g g(-1) platinum, for 8 weeks. Following exposure, surviving snails were sacrificed, shell and remaining tissue investigated by ICP-MS, and shell, midgut gland and mantle by nano-secondary ion mass-spectrometry (Nano-SIMS). (12)C(14)N-normalized platinum and (40)Ca-normalized chromium measurements indicated highest enrichments in cellular vesicles of the midgut gland, and lower concentrations in mantle and shell, with significantly higher platinum and chromium concentrations in the 2 exposure groups vs. control (P&lt;0.05), with somewhat differing distribution patterns for chromium and platinum. Comparable results were obtained by ICP-MS, with both chromium and platinum fed snails showing drastically elevated concentrations of metals in shell (up to 78 and 122 ?g g(-1) dw platinum and chromium, respectively) and in other tissues (up to 200 and 1125 ?g g(-1) dw platinum and chromium, respectively). Nano-SIMS allowed for semi-quantitative comparison of metal fate in snail tissues, making this an interesting technique for future studies in the area of environmental pollution.","Determination of oral uptake and biodistribution of platinum and chromium by the garden snail (Helix aspersa) employing nano-secondary ion mass-spectrometry Abs: Environmental heavy metal contamination is a case of concern for both animal and human health. Studying the fate of metals in plant or animal tissues may provide information on pollution. In the present study, we investigated the possibility to follow the biological fate of chromium and platinum uptake in common garden snails (Helix aspersa), typically accumulating high concentrations of metals from their environment. Chromium and platinum were administered orally to snails in 5 groups (n=25/group): control, food contaminated by ca. 2.5 ?g g(-1) and 19 ?g g(-1) chromium and 2.5 ?g g(-1) and 25 ?g g(-1) platinum, for 8 weeks. Following exposure, surviving snails were sacrificed, shell and remaining tissue investigated by ICP-MS, and shell, midgut gland and mantle by nano-secondary ion mass-spectrometry (Nano-SIMS). (12)C(14)N-normalized platinum and (40)Ca-normalized chromium measurements indicated highest enrichments in cellular vesicles of the midgut gland, and lower concentrations in mantle and shell, with significantly higher platinum and chromium concentrations in the 2 exposure groups vs. control (P&lt;0.05), with somewhat differing distribution patterns for chromium and platinum. Comparable results were obtained by ICP-MS, with both chromium and platinum fed snails showing drastically elevated concentrations of metals in shell (up to 78 and 122 ?g g(-1) dw platinum and chromium, respectively) and in other tissues (up to 200 and 1125 ?g g(-1) dw platinum and chromium, respectively). Nano-SIMS allowed for semi-quantitative comparison of metal fate in snail tissues, making this an interesting technique for future studies in the area of environmental pollution."
1786323,Evans et al. 2013,Photostabilization of wood using low molecular weight phenol formaldehyde resin and hindered amine light stabilizer,,Photostabilization of wood using low molecular weight phenol formaldehyde resin and hindered amine light stabilizer Abs: 
1786322,Espada-Bellido et al. 2013,Determination of chromium in estuarine waters by catalytic cathodic stripping voltammetry using a vibrating silver amalgam microwire electrode,"Chromium (Cr(VI)) in water can be determined by adsorptive catalytic cathodic stripping voltammetry in the presence of diethylenetriaminepentaacetic acid (DTPA) and nitrate on the hanging mercury drop electrode (HMDE). Predominately Cr(VI) is detected and the water is UV-digested to convert all Cr to Cr(VI) prior to analysis. We develop here an alternative to the HMDE by using a silver amalgam electrode based on a vibrating microwire. The microwire electrodes were 12.5 ?m in diameter and electrochemically coated with mercury, and were stable for a week. Conditions were re-optimised, and we used a DTPA concentration of 5mM, 30 mM acetate pH buffer (pH 5.5 in seawater and pH 5.8 in pure water), and 1.5M nitrate solution. The microwire was reactivated prior to each scan by applying a negative potential (-3V) for 2s which removed all deposited Cr. The detection limit for chromium in pH buffer was found to be 0.2 nM Cr(VI) and in seawater 0.3 nM Cr(VI) at a deposition time of 30s. The response increased linearly with the concentration of Cr(VI) up to 60 nM Cr(VI) in seawater. The limit of detection is less good than using the HMDE, but the linear range is good and the microwire electrode could form the basis of apparatus for flow-analysis. The method was successfully tested on water samples from the estuary of the river Mersey (Liverpool Bay) giving chromium concentrations between 1.48 nM and 2.29 nM.","Determination of chromium in estuarine waters by catalytic cathodic stripping voltammetry using a vibrating silver amalgam microwire electrode Abs: Chromium (Cr(VI)) in water can be determined by adsorptive catalytic cathodic stripping voltammetry in the presence of diethylenetriaminepentaacetic acid (DTPA) and nitrate on the hanging mercury drop electrode (HMDE). Predominately Cr(VI) is detected and the water is UV-digested to convert all Cr to Cr(VI) prior to analysis. We develop here an alternative to the HMDE by using a silver amalgam electrode based on a vibrating microwire. The microwire electrodes were 12.5 ?m in diameter and electrochemically coated with mercury, and were stable for a week. Conditions were re-optimised, and we used a DTPA concentration of 5mM, 30 mM acetate pH buffer (pH 5.5 in seawater and pH 5.8 in pure water), and 1.5M nitrate solution. The microwire was reactivated prior to each scan by applying a negative potential (-3V) for 2s which removed all deposited Cr. The detection limit for chromium in pH buffer was found to be 0.2 nM Cr(VI) and in seawater 0.3 nM Cr(VI) at a deposition time of 30s. The response increased linearly with the concentration of Cr(VI) up to 60 nM Cr(VI) in seawater. The limit of detection is less good than using the HMDE, but the linear range is good and the microwire electrode could form the basis of apparatus for flow-analysis. The method was successfully tested on water samples from the estuary of the river Mersey (Liverpool Bay) giving chromium concentrations between 1.48 nM and 2.29 nM."
1786321,El Bestawy et al. 2013,Optimization and/or acclimatization of activated sludge process under heavy metals stress,"The present study aimed to overcome the toxicity of the heavy metals load, discharged with the industrial effluents into Alexandria sewerage network, on the activated sludge treatment system through effective acclimation for organic matter and heavy metals removal. Optimization and/or acclimatization of the activated sludge process in the presence of Cu, Cd, Co and Cr contaminating mixed domestic-industrial wastewater was investigated. Acclimatization process was performed through abrupt and stepwise addition of tested metals using sequencing batch reactors treatment approach and evaluated as microbial oxygen uptake rate (OUR), dehydrogenase activity (DHA), organic matter (COD) and heavy metals removal. Abrupt addition of metals adversely affected sludge bioactivity leading to decline in the removal efficiency of the targeted contaminants and loss of floc structure. Metals IC50 confirmed that copper possessed the highest toxicity towards the OUR, DHA activity and COD removal with orders Cu &gt; Cd &gt; Cr &gt; Co; Cu &gt; Cd &gt; Co = Cr and Cu &gt; Cd &gt; Cr &gt; Co, respectively. The highest metal removal was recorded for Cd followed by Co, Cu and finally Cr, most of which was retained in the dissolved influent. However, controlled stepwise application of the tested metals exhibited high sensitivity of DHA and OUR activities only at the highest metal concentrations although enhanced at the lowest concentrations while COD removal was not significantly affected. In conclusion, this approach resulted in adaptation of the system where sludge microbes acquired and developed natural resistance to such metals leading to remarkable enhancement of both organic matter and heavy metals removal.","Optimization and/or acclimatization of activated sludge process under heavy metals stress Abs: The present study aimed to overcome the toxicity of the heavy metals load, discharged with the industrial effluents into Alexandria sewerage network, on the activated sludge treatment system through effective acclimation for organic matter and heavy metals removal. Optimization and/or acclimatization of the activated sludge process in the presence of Cu, Cd, Co and Cr contaminating mixed domestic-industrial wastewater was investigated. Acclimatization process was performed through abrupt and stepwise addition of tested metals using sequencing batch reactors treatment approach and evaluated as microbial oxygen uptake rate (OUR), dehydrogenase activity (DHA), organic matter (COD) and heavy metals removal. Abrupt addition of metals adversely affected sludge bioactivity leading to decline in the removal efficiency of the targeted contaminants and loss of floc structure. Metals IC50 confirmed that copper possessed the highest toxicity towards the OUR, DHA activity and COD removal with orders Cu &gt; Cd &gt; Cr &gt; Co; Cu &gt; Cd &gt; Co = Cr and Cu &gt; Cd &gt; Cr &gt; Co, respectively. The highest metal removal was recorded for Cd followed by Co, Cu and finally Cr, most of which was retained in the dissolved influent. However, controlled stepwise application of the tested metals exhibited high sensitivity of DHA and OUR activities only at the highest metal concentrations although enhanced at the lowest concentrations while COD removal was not significantly affected. In conclusion, this approach resulted in adaptation of the system where sludge microbes acquired and developed natural resistance to such metals leading to remarkable enhancement of both organic matter and heavy metals removal."
1786320,Ejaz et al. 2013,"Biotransformation potential of hexavalent chromium by Bacillus pumilus-S4, Pseudomonas doudoroffii-S5 and Exiguobacterium-S8 in association with hydrophytes",,"Biotransformation potential of hexavalent chromium by Bacillus pumilus-S4, Pseudomonas doudoroffii-S5 and Exiguobacterium-S8 in association with hydrophytes Abs: "
1786319,Duan et al. 2013,A simple and effective method for detecting toxicity of chromium trioxide on Vicia faba,,A simple and effective method for detecting toxicity of chromium trioxide on Vicia faba Abs: 
1786318,Dong et al. 2013,Effects of geochemical constituents on the zero-valent iron reductive removal of nitrobenzene in groundwater,,Effects of geochemical constituents on the zero-valent iron reductive removal of nitrobenzene in groundwater Abs: 
1786317,Dong et al. 2013,Formation of soluble Cr(III) end-products and nanoparticles during Cr(VI) reduction by Bacillus cereus strain XMCr-6,,Formation of soluble Cr(III) end-products and nanoparticles during Cr(VI) reduction by Bacillus cereus strain XMCr-6 Abs: 
1786316,Djamaà et al. 2013,Removal of Hexavalent Chromium from Aqueous Solutions using N-octyl Quaternized Poly(4-vinylpyridine): Kinetic and Equilibrium Studies,,Removal of Hexavalent Chromium from Aqueous Solutions using N-octyl Quaternized Poly(4-vinylpyridine): Kinetic and Equilibrium Studies Abs: 
1786314,Das et al. 2013,"Heavy metal contamination, physico-chemical and microbial evaluation of water samples collected from chromite mine environment of Sukinda, India",,"Heavy metal contamination, physico-chemical and microbial evaluation of water samples collected from chromite mine environment of Sukinda, India Abs: "
1786313,Copello et al. 2013,Polyphenol-SiO2 hybrid biosorbent for heavy metal removal. Yerba mate waste (Ilex paraguariensis) as polyphenol source: kinetics and isotherm studies,"A low-cost biosorbent hybrid material ready for application was obtained in this work. Yerba mate (Ilex paraguariensis) milling residual dust was used as a polyphenol source by ethanolic extraction. Polyphenols were immobilized within a SiO(2) matrix to form an interpenetrated polymer after glutaraldehyde cross-linking. Pb(II), Cr(III) and Cr(VI) were chosen as model metals for adsorption. The hybrid materials were characterized by Fourier Transform Infrared Spectroscopy (FTIR), Scanning Electron Microscopy (SEM), Energy Dispersive X-Ray Spectroscopy (EDS) and Nitrogen Adsorption Isotherms. Adsorption experimental data were analysed using Langmuir, Freundlich, Dubinin-Radushkevich, Temkin, Redlich-Peterson, Sips and Toth isotherm models along with the evaluation of adsorption energy and standard free energy (?G°). The adsorption was observed to be pH dependent. The main mechanism of metal adsorption was found to be a spontaneous charge associated interaction. Electron Spin Resonance (ESR) spectroscopy confirmed that Cr(VI) adsorption was an adsorption-coupled reaction and the adsorbed specie was Cr(V). The hybrid matrix probed its adsorption capacity of Cr(III) in a non-treated tannery wastewater.","Polyphenol-SiO2 hybrid biosorbent for heavy metal removal. Yerba mate waste (Ilex paraguariensis) as polyphenol source: kinetics and isotherm studies Abs: A low-cost biosorbent hybrid material ready for application was obtained in this work. Yerba mate (Ilex paraguariensis) milling residual dust was used as a polyphenol source by ethanolic extraction. Polyphenols were immobilized within a SiO(2) matrix to form an interpenetrated polymer after glutaraldehyde cross-linking. Pb(II), Cr(III) and Cr(VI) were chosen as model metals for adsorption. The hybrid materials were characterized by Fourier Transform Infrared Spectroscopy (FTIR), Scanning Electron Microscopy (SEM), Energy Dispersive X-Ray Spectroscopy (EDS) and Nitrogen Adsorption Isotherms. Adsorption experimental data were analysed using Langmuir, Freundlich, Dubinin-Radushkevich, Temkin, Redlich-Peterson, Sips and Toth isotherm models along with the evaluation of adsorption energy and standard free energy (?G°). The adsorption was observed to be pH dependent. The main mechanism of metal adsorption was found to be a spontaneous charge associated interaction. Electron Spin Resonance (ESR) spectroscopy confirmed that Cr(VI) adsorption was an adsorption-coupled reaction and the adsorbed specie was Cr(V). The hybrid matrix probed its adsorption capacity of Cr(III) in a non-treated tannery wastewater."
1786312,Copaciu et al. 2013,"Diffuse Water Pollution by Anthraquinone and Azo Dyes in Environment Importantly Alters Foliage Volatiles, Carotenoids and Physiology in Wheat (Triticum aestivum)",,"Diffuse Water Pollution by Anthraquinone and Azo Dyes in Environment Importantly Alters Foliage Volatiles, Carotenoids and Physiology in Wheat (Triticum aestivum) Abs: "
1786311,Cirik et al. 2013,Effect of electron donor source on the treatment of Cr(VI)-containing textile wastewater using sulfate-reducing fluidized bed reactors (FBRs),"The treatment of Cr(VI) containing textile wastewater was studied in ethanol and glucose-fed sulfate-reducing fluidized bed reactors at 35°C for around 250 days. The synthetic wastewater contained Cr(VI) (5-45 mg L(-1)), azo dye (Remazol Brilliant Violet 5R) (100-200 mg L(-1)), sulfate (2000 mg L(-1)) and ethanol or glucose (2000 mg L(-1) chemical oxygen demand (COD)). The robustness of two FBRs was assessed under varying Cr(VI) and azo dye loadings. Both reactors performed well in terms of COD, sulfate, color and Cr(VI) removals. However, ethanol-fed FBR performed better than glucose-fed one. The COD, sulfate, chromium and color removals at the highest Cr(VI) concentration (45 mg L(-1)) in ethanol-fed FBR were around 75%, 95%, 93%, and 99%, respectively. Further increase in influent Cr(VI) concentration adversely effected reactor performance. The COD, sulfate, chromium and color removals at 45 mg L(-1) Cr(VI) in glucose-fed FBR were around 60%, 50%, 93%, and 76%, respectively.","Effect of electron donor source on the treatment of Cr(VI)-containing textile wastewater using sulfate-reducing fluidized bed reactors (FBRs) Abs: The treatment of Cr(VI) containing textile wastewater was studied in ethanol and glucose-fed sulfate-reducing fluidized bed reactors at 35°C for around 250 days. The synthetic wastewater contained Cr(VI) (5-45 mg L(-1)), azo dye (Remazol Brilliant Violet 5R) (100-200 mg L(-1)), sulfate (2000 mg L(-1)) and ethanol or glucose (2000 mg L(-1) chemical oxygen demand (COD)). The robustness of two FBRs was assessed under varying Cr(VI) and azo dye loadings. Both reactors performed well in terms of COD, sulfate, color and Cr(VI) removals. However, ethanol-fed FBR performed better than glucose-fed one. The COD, sulfate, chromium and color removals at the highest Cr(VI) concentration (45 mg L(-1)) in ethanol-fed FBR were around 75%, 95%, 93%, and 99%, respectively. Further increase in influent Cr(VI) concentration adversely effected reactor performance. The COD, sulfate, chromium and color removals at 45 mg L(-1) Cr(VI) in glucose-fed FBR were around 60%, 50%, 93%, and 76%, respectively."
1786310,Çimen et al. 2013,Speciation and Preconcentration of Chromium from Water and Food Samples by Synthesized Chelating Resin,,Speciation and Preconcentration of Chromium from Water and Food Samples by Synthesized Chelating Resin Abs: 
1786309,Chrysochoou et al. 2013,Aerobic Cr(VI) Reduction by Bacteria in Culture and Soil Conditions,,Aerobic Cr(VI) Reduction by Bacteria in Culture and Soil Conditions Abs: 
1786308,Chakravarty et al. 2013,"Biosorptive removal of chromium by husk of Lathyrus sativus : Evaluation of the binding mechanism, kinetic and equilibrium study",,"Biosorptive removal of chromium by husk of Lathyrus sativus : Evaluation of the binding mechanism, kinetic and equilibrium study Abs: "
1786307,Cetin et al. 2013,Removal and Recovery of Chromium from Solutions Simulating Tannery Wastewater by Strong Acid Cation Exchanger,,Removal and Recovery of Chromium from Solutions Simulating Tannery Wastewater by Strong Acid Cation Exchanger Abs: 
1786306,Cederkvist et al. 2013,Characterization of chromium species in urban runoff,"Little is known about the presence of the element Cr in its toxic hexavalent form Cr(VI) in stormwater runoff from urban areas. Most studies report only total Cr concentration, i.e., including also the nontoxic Cr(III) molecular form. The objective of this study was to evaluate a field method based on cation-exchange for characterization of Cr species in urban stormwater runoff and soil leachate. We used a 0.05 mol L Na and Ca solution and a soil leachate as matrices and spiked these with Cr(III), Cr(VI), or both in the concentration range of 1 to 100 ?g L. We then filtered the test samples through cation-exchange cartridges. In the Na-Ca salt matrix, the Cr(III) was retained 100% and recovery values of Cr(VI) were 86 to 100%. Furthermore, in such a matrix, each cartridge could be reused at least nine times without a drop in retention of Cr(III) or recovery of Cr(VI). In a soil leachate matrix, the method appeared less applicable. Apparently Cr(III) forms complexes with dissolved organic matter, allowing it to bypass the cartridge, resulting in incomplete Cr(III) retention and thus incomplete speciation. The complexes are formed rapidly after spiking, thus changes in the Cr-species distribution are likely to occur within a few hours when fresh samples are stored. Furthermore, we concluded that Cr(III) at neutral pH in pure solution or complexed with dissolved organic C can sorb irreversibly to polyethylene and polypropylene containers. Our findings show that there is still a need for a method that can be applied to urban runoff in the field. Furthermore, cartridge speciation methods should ideally be tested before being applied on solutions containing organic matter.","Characterization of chromium species in urban runoff Abs: Little is known about the presence of the element Cr in its toxic hexavalent form Cr(VI) in stormwater runoff from urban areas. Most studies report only total Cr concentration, i.e., including also the nontoxic Cr(III) molecular form. The objective of this study was to evaluate a field method based on cation-exchange for characterization of Cr species in urban stormwater runoff and soil leachate. We used a 0.05 mol L Na and Ca solution and a soil leachate as matrices and spiked these with Cr(III), Cr(VI), or both in the concentration range of 1 to 100 ?g L. We then filtered the test samples through cation-exchange cartridges. In the Na-Ca salt matrix, the Cr(III) was retained 100% and recovery values of Cr(VI) were 86 to 100%. Furthermore, in such a matrix, each cartridge could be reused at least nine times without a drop in retention of Cr(III) or recovery of Cr(VI). In a soil leachate matrix, the method appeared less applicable. Apparently Cr(III) forms complexes with dissolved organic matter, allowing it to bypass the cartridge, resulting in incomplete Cr(III) retention and thus incomplete speciation. The complexes are formed rapidly after spiking, thus changes in the Cr-species distribution are likely to occur within a few hours when fresh samples are stored. Furthermore, we concluded that Cr(III) at neutral pH in pure solution or complexed with dissolved organic C can sorb irreversibly to polyethylene and polypropylene containers. Our findings show that there is still a need for a method that can be applied to urban runoff in the field. Furthermore, cartridge speciation methods should ideally be tested before being applied on solutions containing organic matter."
1786305,González et al. 2013,Oxidation of carbohydrates of biological importance by the aquachromium(IV) ion,,Oxidation of carbohydrates of biological importance by the aquachromium(IV) ion Abs: 
1786303,Campos et al. 2013,Foundry sands as low-cost adsorbent material for Cr (VI) removal,,Foundry sands as low-cost adsorbent material for Cr (VI) removal Abs: 
1786302,Cáliz et al. 2013,"Emerging resistant microbiota from an acidic soil exposed to toxicity of Cr, Cd and Pb is mainly influenced by the bioavailability of these metals",,"Emerging resistant microbiota from an acidic soil exposed to toxicity of Cr, Cd and Pb is mainly influenced by the bioavailability of these metals Abs: "
1786301,Butler et al. 2013,"Synthesis and spectroscopic characterization of complexes of Cr(III), Cr(VI), Cu(III), Zn(II), Mo(VI), Pd(II), Ag(III), Au(III) and W(VI) with telluric acid",,"Synthesis and spectroscopic characterization of complexes of Cr(III), Cr(VI), Cu(III), Zn(II), Mo(VI), Pd(II), Ag(III), Au(III) and W(VI) with telluric acid Abs: "
1786300,Burks et al. 2013,Removal of Chromium(VI) Using Surface Modified Superparamagnetic Iron Oxide Nanoparticles,"This study describes the removal of Chromium(VI) from aqueous solutions using surface tailored superparamagnetic iron oxide nanoparticles (SPION) coated with bis(2,4,4-trimethylpentyl)dithiophosphinic acid (Cyanex-301). The synthesized Cyanex-301 coated SPION has been characterized by Transmission Electron Microscopy (TEM), Fourier-Transfer Infrared Spectroscopy (FT-IR), X-ray Photonic Spectroscopy (XPS), and Thermogravimetric Analysis (TGA). The adsorption mechanism was proposed to be via complexation between the thiol group on Cyanex-301 and Cr(VI) ions based on the XPS and FTIR analysis. It has been found that the equilibrium can be attained in less than 2hr. The adsorption behavior of Cr(VI) on the Cyanex-301 coated SPION can be well described by the Langmuir model and the maximum adsorption capacity for Cr(VI) was estimated to be 30.8mg/g. The selectivity of the Cyanex-301 coated SPION adsorbent towards Cr(VI) ions was found to be high and the maximum loading capacity obtained is up to an order of magnitude higher than that of other adsorbents reported in the literature. The desorption studies showed that more than 70% of Cr(VI) can be recovered using HNO3 as eluting solution. Our findings suggest a high potential of the designed adsorbent material for the treatment of industrial wastewater containing Cr(VI).","Removal of Chromium(VI) Using Surface Modified Superparamagnetic Iron Oxide Nanoparticles Abs: This study describes the removal of Chromium(VI) from aqueous solutions using surface tailored superparamagnetic iron oxide nanoparticles (SPION) coated with bis(2,4,4-trimethylpentyl)dithiophosphinic acid (Cyanex-301). The synthesized Cyanex-301 coated SPION has been characterized by Transmission Electron Microscopy (TEM), Fourier-Transfer Infrared Spectroscopy (FT-IR), X-ray Photonic Spectroscopy (XPS), and Thermogravimetric Analysis (TGA). The adsorption mechanism was proposed to be via complexation between the thiol group on Cyanex-301 and Cr(VI) ions based on the XPS and FTIR analysis. It has been found that the equilibrium can be attained in less than 2hr. The adsorption behavior of Cr(VI) on the Cyanex-301 coated SPION can be well described by the Langmuir model and the maximum adsorption capacity for Cr(VI) was estimated to be 30.8mg/g. The selectivity of the Cyanex-301 coated SPION adsorbent towards Cr(VI) ions was found to be high and the maximum loading capacity obtained is up to an order of magnitude higher than that of other adsorbents reported in the literature. The desorption studies showed that more than 70% of Cr(VI) can be recovered using HNO3 as eluting solution. Our findings suggest a high potential of the designed adsorbent material for the treatment of industrial wastewater containing Cr(VI)."
1786299,Brito et al. 2013,Bacterial biodiversity from anthropogenic extreme environments: a hyper-alkaline and hyper-saline industrial residue contaminated by chromium and iron,"Anthropogenic extreme environments are among the most interesting sites for the bioprospection of extremophiles since the selection pressures may favor the presence of microorganisms of great interest for taxonomical and astrobiological research as well as for bioremediation technologies and industrial applications. In this work, T-RFLP and 16S rRNA gene library analyses were carried out to describe the autochthonous bacterial populations from an industrial waste characterized as hyper-alkaline (pH between 9 and 14), hyper-saline (around 100 PSU) and highly contaminated with metals, mainly chromium (from 5 to 18 g kg(-1)) and iron (from 2 to 108 g kg(-1)). Due to matrix interference with DNA extraction, a protocol optimization step was required in order to carry out molecular analyses. The most abundant populations, as evaluated by both T-RFLP and 16S rRNA gene library analyses, were affiliated to Bacillus and Lysobacter genera. Lysobacter related sequences were present in the three samples: solid residue and lixiviate sediments from both dry and wet seasons. Sequences related to Thiobacillus were also found; although strains affiliated to this genus are known to have tolerance to metals, they have not previously been detected in alkaline environments. Together with Bacillus (already described as a metal reducer), such organisms could be of use in bioremediation technologies for reducing chromium, as well as for the prospection of enzymes of biotechnological interest.","Bacterial biodiversity from anthropogenic extreme environments: a hyper-alkaline and hyper-saline industrial residue contaminated by chromium and iron Abs: Anthropogenic extreme environments are among the most interesting sites for the bioprospection of extremophiles since the selection pressures may favor the presence of microorganisms of great interest for taxonomical and astrobiological research as well as for bioremediation technologies and industrial applications. In this work, T-RFLP and 16S rRNA gene library analyses were carried out to describe the autochthonous bacterial populations from an industrial waste characterized as hyper-alkaline (pH between 9 and 14), hyper-saline (around 100 PSU) and highly contaminated with metals, mainly chromium (from 5 to 18 g kg(-1)) and iron (from 2 to 108 g kg(-1)). Due to matrix interference with DNA extraction, a protocol optimization step was required in order to carry out molecular analyses. The most abundant populations, as evaluated by both T-RFLP and 16S rRNA gene library analyses, were affiliated to Bacillus and Lysobacter genera. Lysobacter related sequences were present in the three samples: solid residue and lixiviate sediments from both dry and wet seasons. Sequences related to Thiobacillus were also found; although strains affiliated to this genus are known to have tolerance to metals, they have not previously been detected in alkaline environments. Together with Bacillus (already described as a metal reducer), such organisms could be of use in bioremediation technologies for reducing chromium, as well as for the prospection of enzymes of biotechnological interest."
1786298,Bolan et al. 2013,"Rhizoreduction of arsenate and chromate in Australian native grass, shrub and tree vegetation",,"Rhizoreduction of arsenate and chromate in Australian native grass, shrub and tree vegetation Abs: "
1786297,Bennett et al. 2013,Reduction of hexavalent chromium using fungi and bacteria isolated from contaminated soil and water samples,,Reduction of hexavalent chromium using fungi and bacteria isolated from contaminated soil and water samples Abs: 
1786296,Benhamou et al. 2013,Amino-functionalized MCM-41 and MCM-48 for the removal of chromate and arsenate,"The aim of the present work was to investigate the efficiency of three amino-functionalized (hexadecylamine, dodecylamine, and dimethyldodecylamine) mesoporous silicas (MCM-41 and MCM-48) toward the adsorption of arsenate and chromate. Hexadecylamine-functionalized materials were characterized; BET surface areas, pore volumes, and sizes decreased with the functionalization, whereas XRD patterns show that the hexagonal structure of MCM-41 and the cubic structure of MCM-48 were not modified. The zeta potential decreases with pH and the highest arsenate and chromate removal was observed at the lowest pHs. Adsorption of chromium and arsenate was significantly enhanced after functionalization and amino-functionalized MCM-41 adsorb larger amounts of arsenate when compared to expanded MCM-48 materials. Chromate sorption capacities increased with the chain length and the larger capacities were obtained with hexadecylamine-functionalized mesoporous silicas. Mesoporous silicas modified by dimethyldodecylamine exhibited the higher arsenate sorption capacities.","Amino-functionalized MCM-41 and MCM-48 for the removal of chromate and arsenate Abs: The aim of the present work was to investigate the efficiency of three amino-functionalized (hexadecylamine, dodecylamine, and dimethyldodecylamine) mesoporous silicas (MCM-41 and MCM-48) toward the adsorption of arsenate and chromate. Hexadecylamine-functionalized materials were characterized; BET surface areas, pore volumes, and sizes decreased with the functionalization, whereas XRD patterns show that the hexagonal structure of MCM-41 and the cubic structure of MCM-48 were not modified. The zeta potential decreases with pH and the highest arsenate and chromate removal was observed at the lowest pHs. Adsorption of chromium and arsenate was significantly enhanced after functionalization and amino-functionalized MCM-41 adsorb larger amounts of arsenate when compared to expanded MCM-48 materials. Chromate sorption capacities increased with the chain length and the larger capacities were obtained with hexadecylamine-functionalized mesoporous silicas. Mesoporous silicas modified by dimethyldodecylamine exhibited the higher arsenate sorption capacities."
1786295,Villegas et al. 2013,"The effect of sulphate and phosphate ions on Cr(VI) reduction by Streptomyces sp. MC1, including studies of growth and pleomorphism",,"The effect of sulphate and phosphate ions on Cr(VI) reduction by Streptomyces sp. MC1, including studies of growth and pleomorphism Abs: "
1786294,Bartholomäus et al. 2013,"Isolation, characterization, and nuclease activity of biologically relevant chromium(V) complexes with monosaccharides and model diols. Likely intermediates in chromium-induced cancers","The stabilization of Cr(V) by biological 1,2-diolato ligands, including carbohydrates, glycoproteins, and sialic acid derivatives, is likely to play a crucial role in the genotoxicity of Cr(VI) and has also been implicated in the antidiabetic effect of Cr(III). Previously, such complexes have been observed by electron paramagnetic resonance (EPR) spectroscopy in living cells or animals, treated with carcinogenic Cr(VI), as well as in numerous model systems, but attempts to isolate them have been elusive. Recently, the first crystal structure of a Cr(V) complex with cis-1,2-cyclohexanediol (1, a close structural analogue of carbohydrates) has been reported. In this work, Cr(V) complexes of the general formula [Cr(V)OL2](-) [where LH2 = 1, cis-1,2-cyclopentanediol (2), D-glucose (3), D-mannose (4), D-galactose (5), and D-ribose (6)] have been isolated from light-catalyzed reactions of Cr(VI) (anhydrous Na2Cr2O7) with slight molar excesses of the corresponding ligands in N,N-dimethylformamide. The complexes were characterized by elemental analyses, electrospray mass spectrometry (ESMS), and EPR spectroscopy. Studies by electronic absorption spectroscopy have shown that the solids isolated from reactions of Cr(VI) with 3-6 contained mixtures of Cr(V) complexes (40-65 mol %) and Cr(III) species (probably complexes with oxidized ligands), while those from reactions with 1 and 2 were practically pure Cr(V). The first isolation of solids containing significant proportions of chromium(V) monosaccharide complexes led to the definitive assignment of their general formula ([Cr(V)OL2](-), based on ESMS), in agreement with the earlier EPR spectroscopic data. The first direct comparison of the decomposition rates of Cr(V) complexes with 1-6, made possible by isolation of the solids, have shown that the complexes with five-membered-ring ligands (2 and 6) are more stable at pH ? 7 compared with their six-membered-ring counterparts (1 and 3-5). This finding emphasizes the likely biological roles of chromium(V) pentose complexes, e.g., those with sugar residues of RNA, ATP, or NAD(P)H. Finally, the first direct evidence for the ability of these Cr(V) complexes to cause oxidative DNA damage in the absence of added reductants or oxidants has been obtained. These data support significant roles for chromium(V) 1,2-diolato complexes in the diverse biological activities of Cr(VI) and Cr(III).","Isolation, characterization, and nuclease activity of biologically relevant chromium(V) complexes with monosaccharides and model diols. Likely intermediates in chromium-induced cancers Abs: The stabilization of Cr(V) by biological 1,2-diolato ligands, including carbohydrates, glycoproteins, and sialic acid derivatives, is likely to play a crucial role in the genotoxicity of Cr(VI) and has also been implicated in the antidiabetic effect of Cr(III). Previously, such complexes have been observed by electron paramagnetic resonance (EPR) spectroscopy in living cells or animals, treated with carcinogenic Cr(VI), as well as in numerous model systems, but attempts to isolate them have been elusive. Recently, the first crystal structure of a Cr(V) complex with cis-1,2-cyclohexanediol (1, a close structural analogue of carbohydrates) has been reported. In this work, Cr(V) complexes of the general formula [Cr(V)OL2](-) [where LH2 = 1, cis-1,2-cyclopentanediol (2), D-glucose (3), D-mannose (4), D-galactose (5), and D-ribose (6)] have been isolated from light-catalyzed reactions of Cr(VI) (anhydrous Na2Cr2O7) with slight molar excesses of the corresponding ligands in N,N-dimethylformamide. The complexes were characterized by elemental analyses, electrospray mass spectrometry (ESMS), and EPR spectroscopy. Studies by electronic absorption spectroscopy have shown that the solids isolated from reactions of Cr(VI) with 3-6 contained mixtures of Cr(V) complexes (40-65 mol %) and Cr(III) species (probably complexes with oxidized ligands), while those from reactions with 1 and 2 were practically pure Cr(V). The first isolation of solids containing significant proportions of chromium(V) monosaccharide complexes led to the definitive assignment of their general formula ([Cr(V)OL2](-), based on ESMS), in agreement with the earlier EPR spectroscopic data. The first direct comparison of the decomposition rates of Cr(V) complexes with 1-6, made possible by isolation of the solids, have shown that the complexes with five-membered-ring ligands (2 and 6) are more stable at pH ? 7 compared with their six-membered-ring counterparts (1 and 3-5). This finding emphasizes the likely biological roles of chromium(V) pentose complexes, e.g., those with sugar residues of RNA, ATP, or NAD(P)H. Finally, the first direct evidence for the ability of these Cr(V) complexes to cause oxidative DNA damage in the absence of added reductants or oxidants has been obtained. These data support significant roles for chromium(V) 1,2-diolato complexes in the diverse biological activities of Cr(VI) and Cr(III)."
1786293,Bala et al. 2013,A hexaureachromium(III) complex as a molecular receptor for oxoanions,,A hexaureachromium(III) complex as a molecular receptor for oxoanions Abs: 
1786292,Bag et al. 2013,Substoichiometric extraction of chromium(III) with 2-picolinic acid into n-butanol,,Substoichiometric extraction of chromium(III) with 2-picolinic acid into n-butanol Abs: 
1786291,Avramovic et al. 2013,"Influence of rhamnolipids, produced by Pseudomonas aeruginosa NCAIM(P), B001380 on Cr(VI) removal capacity in liquid medium",,"Influence of rhamnolipids, produced by Pseudomonas aeruginosa NCAIM(P), B001380 on Cr(VI) removal capacity in liquid medium Abs: "
1786290,Augustynowicz et al. 2013,Study on chromium-binding capacity of Callitriche cophocarpa in an aquatic environment,"The aim of the present study was to investigate the binding strength of chromium (Cr) ions to aquatic macrophyte Callitriche cophocarpa. Shoots of the plants were incubated in a natural water solution containing Cr(III) or Cr(VI) at a concentration ranging from 0.5 to 4 mM under laboratory conditions. We found that C. cophocarpa has an extremely high capacity to bind Cr. The average level of accumulation reached 28,385 or 7,315 mg kg(-1) dry weight for plants incubated with Cr(III) or Cr(VI), respectively. Shoots incubated in a 0.5 mM concentration of Cr(III) for 5 days removed almost 100 % of the metal from solution. The major pool of the bound Cr(III) ions follows the strongest mechanism of metal-binding to an organic matter. In contrast, we found that only 25 % of Cr(VI) ions are bound into the metallo-organic compounds and 57 % of Cr(VI) exists in an easily remobilizable form. Activity of a photosynthetic electron transport (as F V/F M) was evaluated with respect to the Cr-binding mechanism. Our results contribute to the development of knowledge on processes controlling bioremediation of heavy-metallic compounds in aquatic systems.","Study on chromium-binding capacity of Callitriche cophocarpa in an aquatic environment Abs: The aim of the present study was to investigate the binding strength of chromium (Cr) ions to aquatic macrophyte Callitriche cophocarpa. Shoots of the plants were incubated in a natural water solution containing Cr(III) or Cr(VI) at a concentration ranging from 0.5 to 4 mM under laboratory conditions. We found that C. cophocarpa has an extremely high capacity to bind Cr. The average level of accumulation reached 28,385 or 7,315 mg kg(-1) dry weight for plants incubated with Cr(III) or Cr(VI), respectively. Shoots incubated in a 0.5 mM concentration of Cr(III) for 5 days removed almost 100 % of the metal from solution. The major pool of the bound Cr(III) ions follows the strongest mechanism of metal-binding to an organic matter. In contrast, we found that only 25 % of Cr(VI) ions are bound into the metallo-organic compounds and 57 % of Cr(VI) exists in an easily remobilizable form. Activity of a photosynthetic electron transport (as F V/F M) was evaluated with respect to the Cr-binding mechanism. Our results contribute to the development of knowledge on processes controlling bioremediation of heavy-metallic compounds in aquatic systems."
1786289,Augustynowicz et al. 2013,Strategy of Cr detoxification by Callitriche cophocarpa,,Strategy of Cr detoxification by Callitriche cophocarpa Abs: 
1786288,Andrade et al. 2013,A digital image-based flow-batch analyzer for determining Al(III) and Cr(VI) in water,,A digital image-based flow-batch analyzer for determining Al(III) and Cr(VI) in water Abs: 
1786287,Aly and  Luca 2013,Uranium extraction from aqueous solution using dried and pyrolyzed tea and coffee wastes,,Uranium extraction from aqueous solution using dried and pyrolyzed tea and coffee wastes Abs: 
1786286,Alves and  Coelho 2013,Selective extraction and preconcentration of chromium using Moringa oleifera husks as biosorbent and flame atomic absorption spectrometry,,Selective extraction and preconcentration of chromium using Moringa oleifera husks as biosorbent and flame atomic absorption spectrometry Abs: 
1786285,Ali et al. 2013,"The influence of silicon on barley growth, photosynthesis and ultra-structure under chromium stress","Silicon (Si) is generally considered as a benefic element for higher plants, especially for those grown under abiotic stressed environments. Current study is carried out in a hydroponic experiment to analyze the effect of Si application on barley growth, photosynthesis and ultra-structure under chromium (Cr) stress. The treatments consisted of three Si (0, 1 and 2mM) and two Cr (0 and 100 ?M) levels. The results showed that Si application at both levels enhanced plant growth relative to the control, and alleviated Cr toxicity, reflected by significant increase in growth and photosynthetic parameters, such as SPAD value, net photosynthetic rate (P(n)), cellular CO(2) concentration (C(i)), stomatal conductance (G(s)) and transpiration rate (T(r)), and chlorophyll fluorescence efficiency (Fv/Fm), with 2mM Si having greater effect than 1mM Si. Cr stress caused ultra-structural disorders in leaves, such as uneven swelling of chloroplast, increased amount of plastoglobuli, disintegrated and disappeared thylakoid membranes, increased size and number of starch granules in leaves, and root ultra-structural modification, including increased vacuolar size, presence of Cr metal in cell walls and vacuoles, disruption and disappearance of nucleus. Exogenous Si alleviated these ultra-structural disorders both in roots and leaves. Apparently, Si and Cr behaved antagonistically, indicating that Si could be a candidate for Cr detoxification in crops under Cr-contaminated soil.","The influence of silicon on barley growth, photosynthesis and ultra-structure under chromium stress Abs: Silicon (Si) is generally considered as a benefic element for higher plants, especially for those grown under abiotic stressed environments. Current study is carried out in a hydroponic experiment to analyze the effect of Si application on barley growth, photosynthesis and ultra-structure under chromium (Cr) stress. The treatments consisted of three Si (0, 1 and 2mM) and two Cr (0 and 100 ?M) levels. The results showed that Si application at both levels enhanced plant growth relative to the control, and alleviated Cr toxicity, reflected by significant increase in growth and photosynthetic parameters, such as SPAD value, net photosynthetic rate (P(n)), cellular CO(2) concentration (C(i)), stomatal conductance (G(s)) and transpiration rate (T(r)), and chlorophyll fluorescence efficiency (Fv/Fm), with 2mM Si having greater effect than 1mM Si. Cr stress caused ultra-structural disorders in leaves, such as uneven swelling of chloroplast, increased amount of plastoglobuli, disintegrated and disappeared thylakoid membranes, increased size and number of starch granules in leaves, and root ultra-structural modification, including increased vacuolar size, presence of Cr metal in cell walls and vacuoles, disruption and disappearance of nucleus. Exogenous Si alleviated these ultra-structural disorders both in roots and leaves. Apparently, Si and Cr behaved antagonistically, indicating that Si could be a candidate for Cr detoxification in crops under Cr-contaminated soil."
1786284,Zafar ali et al. 2013,"A New Polymorph of Potassium Chromate(III), ?-KCrO 2, and Reinvestigation of ?-KCrO 2",,"A New Polymorph of Potassium Chromate(III), ?-KCrO 2, and Reinvestigation of ?-KCrO 2 Abs: "
1786283,Alexovi? et al. 2013,A single-valve sequential injection manifold (SV-SIA) for automation of air-assisted liquid-phase microextraction: stopped flow spectrophotometric determination of chromium(vi),,A single-valve sequential injection manifold (SV-SIA) for automation of air-assisted liquid-phase microextraction: stopped flow spectrophotometric determination of chromium(vi) Abs: 
1786282,Albadarin et al. 2013,Influence of solution chemistry on Cr(VI) reduction and complexation onto date-pits/tea-waste biomaterials,"Tea waste (TW) and Date pits (DP) were investigated for their potential to remove toxic Cr(VI) ions from aqueous solution. Investigations showed that the majority of the bound Cr(VI) ions were reduced to Cr(III) after biosorption at acidic conditions. The electrons for the reduction of Cr(VI) may have been donated from the TW and DP biomasses. The experimental data obtained for Cr(VI)-TW and Cr(VI)-DP at different solution temperatures indicate a multilayer type biosorption, which explains why the Sips isotherm accurately represents the experimental data obtained in this study. The Sips maximum biosorption capacities of Cr(VI) onto TW and DP were 5.768 and 3.199 mmol/g at 333 K, respectively, which is comparatively superior to most other low-cost biomaterials. Fourier transform infrared spectroscopic analysis of the metal loaded biosorbents confirmed the participation of -COOH, -NH(2) and O-CH(3) groups in the reduction and complexation of chromium. Thermodynamic parameters demonstrated that the biosorption of Cr(VI) onto TW and DP biomass was endothermic, spontaneous and feasible at 303-333 K. The results evidently indicated that tea waste and date pits would be suitable biosorbents for Cr(VI) in wastewater under specific conditions.","Influence of solution chemistry on Cr(VI) reduction and complexation onto date-pits/tea-waste biomaterials Abs: Tea waste (TW) and Date pits (DP) were investigated for their potential to remove toxic Cr(VI) ions from aqueous solution. Investigations showed that the majority of the bound Cr(VI) ions were reduced to Cr(III) after biosorption at acidic conditions. The electrons for the reduction of Cr(VI) may have been donated from the TW and DP biomasses. The experimental data obtained for Cr(VI)-TW and Cr(VI)-DP at different solution temperatures indicate a multilayer type biosorption, which explains why the Sips isotherm accurately represents the experimental data obtained in this study. The Sips maximum biosorption capacities of Cr(VI) onto TW and DP were 5.768 and 3.199 mmol/g at 333 K, respectively, which is comparatively superior to most other low-cost biomaterials. Fourier transform infrared spectroscopic analysis of the metal loaded biosorbents confirmed the participation of -COOH, -NH(2) and O-CH(3) groups in the reduction and complexation of chromium. Thermodynamic parameters demonstrated that the biosorption of Cr(VI) onto TW and DP biomass was endothermic, spontaneous and feasible at 303-333 K. The results evidently indicated that tea waste and date pits would be suitable biosorbents for Cr(VI) in wastewater under specific conditions."
1786281,Dehghani mohammad abadi et al. 2013,Supramolecular dispersive liquid–liquid microextraction based solidification of floating organic drops for speciation and spectrophotometric determination of chromium in real samples,,Supramolecular dispersive liquid–liquid microextraction based solidification of floating organic drops for speciation and spectrophotometric determination of chromium in real samples Abs: 
1786280,Zhang et al. 2013,Synthesis and self-assembly of squarelike PbCrO4 nanoplatelets via micelle-mediated depletion attraction,"The self-assembly of nanoparticles triggered by attractive depletion forces presents a versatile pathway for building nanostructural superlattices directly in solution. In this work, the synthesis of squarelike lead chromate (PbCrO4) nanoplatelets is described, and their assembly into well-defined stacks by introducing various types of micelles as depletion agents is studied. The kinetics of the reversible assembly process in solution is probed by light scattering, and the depletion-induced self-assembly of the nanoplatelets is investigated by transmission electron microscopy. For nonionic surfactants, rodlike micelles are found to be more efficient at producing self-assembled particles than are spherelike micelles, in accordance with an increased depletion force. Adding ionic surfactants additionally leads to a segregation of PbCrO4 rod reaction byproducts.","Synthesis and self-assembly of squarelike PbCrO4 nanoplatelets via micelle-mediated depletion attraction Abs: The self-assembly of nanoparticles triggered by attractive depletion forces presents a versatile pathway for building nanostructural superlattices directly in solution. In this work, the synthesis of squarelike lead chromate (PbCrO4) nanoplatelets is described, and their assembly into well-defined stacks by introducing various types of micelles as depletion agents is studied. The kinetics of the reversible assembly process in solution is probed by light scattering, and the depletion-induced self-assembly of the nanoplatelets is investigated by transmission electron microscopy. For nonionic surfactants, rodlike micelles are found to be more efficient at producing self-assembled particles than are spherelike micelles, in accordance with an increased depletion force. Adding ionic surfactants additionally leads to a segregation of PbCrO4 rod reaction byproducts."
1786279,Zhang et al. 2013,Facile preparation of glutathione-stabilized gold nanoclusters for selective determination of chromium (III) and chromium (VI) in environmental water samples,"A novel method for selective determination of Cr(III) and Cr(VI) in environmental water samples was developed based on target-induced fluorescence quenching of glutathione-stabilized gold nanoclusters (GSH-Au NCs). Fluorescent GSH-Au NCs were synthesized by a one-step approach employing GSH as reducing/protecting reagent. It was found that Cr(III) and Cr(VI) showed pH-dependent fluorescence quenching capabilities for GSH-Au NCs, and thus selective determination of Cr(III) and Cr(VI) could be achieved at different pHs. Addition of EDTA was able to effectively eliminate the interferences from other metal ions, leading to a good selectivity for this method. Under optimized conditions, Cr(III) showed a linear range of 25-3800 ?g L(-1) and a limit of detection (LOD) of 2.5 ?g L(-1). The Cr(VI) ion demonstrated a linear range of 5-500 ?g L(-1) and LOD of 0.5 ?g L(-1). The run-to-run relative standard deviations (n=5) for Cr(III) and Cr(VI) were 3.9% and 2.8%, respectively. The recoveries of Cr(III) and Cr(VI) in environmental water samples were also satisfactory (76.3-116%). This method, with its simplicity, low cost, high selectivity and sensitivity, could be used as a promising tool for chromium analysis in environmental water samples.","Facile preparation of glutathione-stabilized gold nanoclusters for selective determination of chromium (III) and chromium (VI) in environmental water samples Abs: A novel method for selective determination of Cr(III) and Cr(VI) in environmental water samples was developed based on target-induced fluorescence quenching of glutathione-stabilized gold nanoclusters (GSH-Au NCs). Fluorescent GSH-Au NCs were synthesized by a one-step approach employing GSH as reducing/protecting reagent. It was found that Cr(III) and Cr(VI) showed pH-dependent fluorescence quenching capabilities for GSH-Au NCs, and thus selective determination of Cr(III) and Cr(VI) could be achieved at different pHs. Addition of EDTA was able to effectively eliminate the interferences from other metal ions, leading to a good selectivity for this method. Under optimized conditions, Cr(III) showed a linear range of 25-3800 ?g L(-1) and a limit of detection (LOD) of 2.5 ?g L(-1). The Cr(VI) ion demonstrated a linear range of 5-500 ?g L(-1) and LOD of 0.5 ?g L(-1). The run-to-run relative standard deviations (n=5) for Cr(III) and Cr(VI) were 3.9% and 2.8%, respectively. The recoveries of Cr(III) and Cr(VI) in environmental water samples were also satisfactory (76.3-116%). This method, with its simplicity, low cost, high selectivity and sensitivity, could be used as a promising tool for chromium analysis in environmental water samples."
1786278,Zaitseva et al. 2013,Chromium(VI) removal via reduction-sorption on bi-functional silica adsorbents,"Organically-modified silica gels bearing mercaptopropyl and ethylenediaminetriacetate groups (SiO2-SH/ED3A) have been used for reduction and subsequent sequestration of Cr(VI) species. The uptake mechanism involves Cr(VI) reduction by thiol groups (SH) and further immobilization of the so-generated Cr(III) species via complexation to the ethylenediaminetriacetate moieties (ED3A). The most appropriate pH range (1-3) for complete Cr(VI) reduction-sorption by SiO2-SH/ED3A originates from the balance between full reduction of Cr(VI) by SH, requiring low pH values, and quantitative complexation of Cr(III) by ED3A, which is favored in less acidic media. Such bi-functional adsorbents are considerably more effective at removal of Cr(VI) than those simply modified with thiol groups alone. The whole reduction-sorption process was characterized by fast kinetics, thus permitting efficient use of the SiO2-SH/ED3A adsorbent in dynamic conditions (column experiments). Monitoring the amount of immobilized chromium species on the solid was achieved using X-ray fluorescence spectroscopy and UV-vis spectroscopy. Studying the influence of ionic strength and presence of heavy metals revealed few interference on Cr(VI) removal.","Chromium(VI) removal via reduction-sorption on bi-functional silica adsorbents Abs: Organically-modified silica gels bearing mercaptopropyl and ethylenediaminetriacetate groups (SiO2-SH/ED3A) have been used for reduction and subsequent sequestration of Cr(VI) species. The uptake mechanism involves Cr(VI) reduction by thiol groups (SH) and further immobilization of the so-generated Cr(III) species via complexation to the ethylenediaminetriacetate moieties (ED3A). The most appropriate pH range (1-3) for complete Cr(VI) reduction-sorption by SiO2-SH/ED3A originates from the balance between full reduction of Cr(VI) by SH, requiring low pH values, and quantitative complexation of Cr(III) by ED3A, which is favored in less acidic media. Such bi-functional adsorbents are considerably more effective at removal of Cr(VI) than those simply modified with thiol groups alone. The whole reduction-sorption process was characterized by fast kinetics, thus permitting efficient use of the SiO2-SH/ED3A adsorbent in dynamic conditions (column experiments). Monitoring the amount of immobilized chromium species on the solid was achieved using X-ray fluorescence spectroscopy and UV-vis spectroscopy. Studying the influence of ionic strength and presence of heavy metals revealed few interference on Cr(VI) removal."
1786277,Alothman et al. 2013,"Kinetic, equilibrium isotherm and thermodynamic studies of Cr(VI) adsorption onto low-cost adsorbent developed from peanut shell activated with phosphoric acid","A particular agricultural waste, peanut shell, has been used as precursor for activated carbon production by chemical activation with H?PO?. Unoxidized activated carbon was prepared in nitrogen atmosphere which was then heated in air at a desired temperature to get oxidized activated carbon. The prepared carbons were characterized for surface area, surface morphology, and pore volume and utilized for the removal of Cr(VI) from aqueous solution. Batch mode experiments were conducted to study the effects of pH, contact time, particle size, adsorbent dose, initial concentration of adsorbate, and temperature on the adsorption of Cr(VI). Cr(VI) adsorption was significantly dependent on solution pH, and the optimum adsorption was observed at pH 2. Pseudo-first-order, pseudo-second-order, and intraparticle diffusion models were used to analyze the kinetic data obtained at different initial Cr(VI) concentrations. The adsorption kinetic data were described very well by the pseudo-second-order model. Equilibrium isotherm data were analyzed by the Langmuir, Freundlich, and Temkin models. The results showed that the Langmuir adsorption isotherm model fitted the data better in the temperature range studied. The adsorption capacity which was found to increase with temperature showed the endothermic nature of Cr(VI) adsorption. The thermodynamic parameters, such as Gibb's Free energy change (?G°), standard enthalpy change (?H°), and standard entropy change (?S°) were evaluated.","Kinetic, equilibrium isotherm and thermodynamic studies of Cr(VI) adsorption onto low-cost adsorbent developed from peanut shell activated with phosphoric acid Abs: A particular agricultural waste, peanut shell, has been used as precursor for activated carbon production by chemical activation with H?PO?. Unoxidized activated carbon was prepared in nitrogen atmosphere which was then heated in air at a desired temperature to get oxidized activated carbon. The prepared carbons were characterized for surface area, surface morphology, and pore volume and utilized for the removal of Cr(VI) from aqueous solution. Batch mode experiments were conducted to study the effects of pH, contact time, particle size, adsorbent dose, initial concentration of adsorbate, and temperature on the adsorption of Cr(VI). Cr(VI) adsorption was significantly dependent on solution pH, and the optimum adsorption was observed at pH 2. Pseudo-first-order, pseudo-second-order, and intraparticle diffusion models were used to analyze the kinetic data obtained at different initial Cr(VI) concentrations. The adsorption kinetic data were described very well by the pseudo-second-order model. Equilibrium isotherm data were analyzed by the Langmuir, Freundlich, and Temkin models. The results showed that the Langmuir adsorption isotherm model fitted the data better in the temperature range studied. The adsorption capacity which was found to increase with temperature showed the endothermic nature of Cr(VI) adsorption. The thermodynamic parameters, such as Gibb's Free energy change (?G°), standard enthalpy change (?H°), and standard entropy change (?S°) were evaluated."
1786276,Yang et al. 2013,Outline of occupational chromium poisoning in China,"The present study analyzed the feature of occupational chromium poisoning in China since the 1980s. The collected data were acquired from 18 previous surveys of chromium poisoning in 14 cities of China. The method of risk assessment was applied to calculate the relative risk and 95 % CI, p < 0.05 was considered as a significant risk. The results showed that nasal disease was the most common sign of occupational chromium poisoning, and the prevalence rate of nasal disease was 17.83 % in total population of 6,998. Further, the risk analysis showed that occupational chromium poisoning led to an increased risk of lung or liver cancer in male workers due to the definite carcinogenicity of hexavalent chromium. Significantly, an increased risk of spontaneous or threatened abortion was also found in female workers. In conclusion, these studies suggest that early detection of impaired reproductive function or impaired lung or liver function in female or male workers is essential for controlling occupational chromium poisoning in China.","Outline of occupational chromium poisoning in China Abs: The present study analyzed the feature of occupational chromium poisoning in China since the 1980s. The collected data were acquired from 18 previous surveys of chromium poisoning in 14 cities of China. The method of risk assessment was applied to calculate the relative risk and 95 % CI, p < 0.05 was considered as a significant risk. The results showed that nasal disease was the most common sign of occupational chromium poisoning, and the prevalence rate of nasal disease was 17.83 % in total population of 6,998. Further, the risk analysis showed that occupational chromium poisoning led to an increased risk of lung or liver cancer in male workers due to the definite carcinogenicity of hexavalent chromium. Significantly, an increased risk of spontaneous or threatened abortion was also found in female workers. In conclusion, these studies suggest that early detection of impaired reproductive function or impaired lung or liver function in female or male workers is essential for controlling occupational chromium poisoning in China."
1786275,Xie et al. 2013,Effect of hexavalent chromium on electron leakage of respiratory chain in mitochondria isolated from rat liver,"<strong>BACKGROUND/AIMS: </strong>In the present study, we explored reactive axygen species (ROS) production in mitochondria, the mechanism of hexavalent chromium (Cr(VI)) hepatotoxicity, and the role of protection by GSH.<br /><br /><strong>METHODS: </strong>Intact mitochondria were isolated from rat liver tissues and mitochondrial basal respiratory rates of NADH and FADH2 respiratory chains were determined. Mitochondria were treated with Cr(VI), GSH and several complex inhibitors. Mitochondria energized by glutamate/malate were separately or jointly treated with Rotenone (Rot), diphenyleneiodonium (DPI) and antimycinA (Ant), while mitochondria energized by succinate were separately or jointly treated with Rot, DPI ' thenoyltrifluoroacetone (TTFA) and Ant.<br /><br /><strong>RESULTS: </strong>Cr(VI) concentration-dependently induced ROS production in the NADH and FADH2 respiratory chain in liver mitochondria. Basal respiratory rate of the mitochondrial FADH2 respiratory chain was significantly higher than that of NADH respiratory chain. Hepatic mitochondrial electron leakage induced by Cr(VI) from NADH respiratory chain were mainly from ubiquinone binding sites of complex I and complex III.<br /><br /><strong>CONCLUSION: </strong>Treatment with 50µM Cr(VI) enhances forward movement of electrons through FADH2 respiratory chain and leaking through the ubiquinone binding site of complex III. Moreover, the protective effect of GSH on liver mitochondria electron leakage is through removing excess H2O2 and reducing total ROS.","Effect of hexavalent chromium on electron leakage of respiratory chain in mitochondria isolated from rat liver Abs: <strong>BACKGROUND/AIMS: </strong>In the present study, we explored reactive axygen species (ROS) production in mitochondria, the mechanism of hexavalent chromium (Cr(VI)) hepatotoxicity, and the role of protection by GSH.<br /><br /><strong>METHODS: </strong>Intact mitochondria were isolated from rat liver tissues and mitochondrial basal respiratory rates of NADH and FADH2 respiratory chains were determined. Mitochondria were treated with Cr(VI), GSH and several complex inhibitors. Mitochondria energized by glutamate/malate were separately or jointly treated with Rotenone (Rot), diphenyleneiodonium (DPI) and antimycinA (Ant), while mitochondria energized by succinate were separately or jointly treated with Rot, DPI ' thenoyltrifluoroacetone (TTFA) and Ant.<br /><br /><strong>RESULTS: </strong>Cr(VI) concentration-dependently induced ROS production in the NADH and FADH2 respiratory chain in liver mitochondria. Basal respiratory rate of the mitochondrial FADH2 respiratory chain was significantly higher than that of NADH respiratory chain. Hepatic mitochondrial electron leakage induced by Cr(VI) from NADH respiratory chain were mainly from ubiquinone binding sites of complex I and complex III.<br /><br /><strong>CONCLUSION: </strong>Treatment with 50µM Cr(VI) enhances forward movement of electrons through FADH2 respiratory chain and leaking through the ubiquinone binding site of complex III. Moreover, the protective effect of GSH on liver mitochondria electron leakage is through removing excess H2O2 and reducing total ROS."
1786274,Xiao et al. 2013,Time?order effects of vitamin C on hexavalent chromium?induced mitochondrial damage and DNA?protein crosslinks in cultured rat peripheral blood lymphocytes,"Hexavalent chromium [Cr(VI)] and its compounds have extensive applications in many industries and are widely known to cause occupational diseases as well as carcinogenic effects in humans. Mitochondrial damage, which is important in Cr(VI)?induced cytotoxicity, may be characterized by the opening status of the permeability transition pore, the maintenance of the mitochondrial membrane potential and the level of malondialdehyde. The formation of DNA?protein crosslinks (DPCs) in target tissues appears to be the direct and primary genotoxic effect of Cr(VI) exposure, and the lymphocytic DPCs may be viewed as a biomarker of internal Cr(VI) accumulation. It is well known that vitamin C (vit C) is an important biological reducing agent in humans and animals, which is capable of reducing Cr(VI). Regardless of the evidence from cell culture and in vivo experiments of the protective effect of the antioxidant, vit C, following exposure to Cr(VI), no studies have been conducted to date to demonstrate the time?order effects of vit C on Cr(VI)?induced mitochondrial damage and DPC formation. In the present study, by using peripheral blood lymphocytes from Sprague?Dawley rats, we demonstrated that vit C pre? and co?treatment have a protective effect against Cr(VI)?induced loss of cell viability and mitochondrial damage, while only vit C co?treatment has a protective effect against the Cr(VI)?induced increase in DPCs. The mechanistic investigation revealed that cellular reactive oxygen species levels are correlated with Cr(VI)?induced mitochondrial damage, and that p53 expression is correlated with the Cr(VI)?induced increase in DPCs. We concluded that vit C exerts different time?order effects on Cr(VI)?induced mitochondrial damage and DPC formation, and that biomarkers, including DPC and p53, may be used in the assessment of the development of Cr(VI)?induced cancer. These findings facilitate more detailed follow?up of the Cr(VI)?exposure populations for secondary prevention.","Time?order effects of vitamin C on hexavalent chromium?induced mitochondrial damage and DNA?protein crosslinks in cultured rat peripheral blood lymphocytes Abs: Hexavalent chromium [Cr(VI)] and its compounds have extensive applications in many industries and are widely known to cause occupational diseases as well as carcinogenic effects in humans. Mitochondrial damage, which is important in Cr(VI)?induced cytotoxicity, may be characterized by the opening status of the permeability transition pore, the maintenance of the mitochondrial membrane potential and the level of malondialdehyde. The formation of DNA?protein crosslinks (DPCs) in target tissues appears to be the direct and primary genotoxic effect of Cr(VI) exposure, and the lymphocytic DPCs may be viewed as a biomarker of internal Cr(VI) accumulation. It is well known that vitamin C (vit C) is an important biological reducing agent in humans and animals, which is capable of reducing Cr(VI). Regardless of the evidence from cell culture and in vivo experiments of the protective effect of the antioxidant, vit C, following exposure to Cr(VI), no studies have been conducted to date to demonstrate the time?order effects of vit C on Cr(VI)?induced mitochondrial damage and DPC formation. In the present study, by using peripheral blood lymphocytes from Sprague?Dawley rats, we demonstrated that vit C pre? and co?treatment have a protective effect against Cr(VI)?induced loss of cell viability and mitochondrial damage, while only vit C co?treatment has a protective effect against the Cr(VI)?induced increase in DPCs. The mechanistic investigation revealed that cellular reactive oxygen species levels are correlated with Cr(VI)?induced mitochondrial damage, and that p53 expression is correlated with the Cr(VI)?induced increase in DPCs. We concluded that vit C exerts different time?order effects on Cr(VI)?induced mitochondrial damage and DPC formation, and that biomarkers, including DPC and p53, may be used in the assessment of the development of Cr(VI)?induced cancer. These findings facilitate more detailed follow?up of the Cr(VI)?exposure populations for secondary prevention."
1786273,Xafenias et al. 2013,Enhanced performance of hexavalent chromium reducing cathodes in the presence of Shewanella oneidensis MR-1 and lactate,"Biocathodes for the reduction of the highly toxic hexavalent chromium (Cr(VI)) were investigated using Shewanella oneidensis MR-1 (MR-1) as a biocatalyst and performance was assessed in terms of current production and Cr(VI) reduction. Potentiostatically controlled experiments (-500 mV vs Ag/AgCl) showed that a mediatorless MR-1 biocathode started up under aerated conditions in the presence of lactate, received 5.5 and 1.7 times more electrons for Cr(VI) reduction over a 4 h operating period than controls without lactate and with lactate but without MR-1, respectively. Cr(VI) reduction was also enhanced, with a decrease in concentration over the 4 h operating period of 9 mg/L Cr(VI), compared to only 1 and 3 mg/L, respectively, in the controls. Riboflavin, an electron shuttle mediator naturally produced by MR-1, was also found to have a positive impact in potentiostatically controlled cathodes. Additionally, a microbial fuel cell (MFC) with MR-1 and lactate present in both anode and cathode produced a maximum current density of 32.5 mA/m(2) (1000 ? external load) after receiving a 10 mg/L Cr(VI) addition in the cathode, and cathodic efficiency increased steadily over an 8 day operation period with successive Cr(VI) additions. In conclusion, effective and continuous Cr(VI) reduction with associated current production were achieved when MR-1 and lactate were both present in the biocathodes.","Enhanced performance of hexavalent chromium reducing cathodes in the presence of Shewanella oneidensis MR-1 and lactate Abs: Biocathodes for the reduction of the highly toxic hexavalent chromium (Cr(VI)) were investigated using Shewanella oneidensis MR-1 (MR-1) as a biocatalyst and performance was assessed in terms of current production and Cr(VI) reduction. Potentiostatically controlled experiments (-500 mV vs Ag/AgCl) showed that a mediatorless MR-1 biocathode started up under aerated conditions in the presence of lactate, received 5.5 and 1.7 times more electrons for Cr(VI) reduction over a 4 h operating period than controls without lactate and with lactate but without MR-1, respectively. Cr(VI) reduction was also enhanced, with a decrease in concentration over the 4 h operating period of 9 mg/L Cr(VI), compared to only 1 and 3 mg/L, respectively, in the controls. Riboflavin, an electron shuttle mediator naturally produced by MR-1, was also found to have a positive impact in potentiostatically controlled cathodes. Additionally, a microbial fuel cell (MFC) with MR-1 and lactate present in both anode and cathode produced a maximum current density of 32.5 mA/m(2) (1000 ? external load) after receiving a 10 mg/L Cr(VI) addition in the cathode, and cathodic efficiency increased steadily over an 8 day operation period with successive Cr(VI) additions. In conclusion, effective and continuous Cr(VI) reduction with associated current production were achieved when MR-1 and lactate were both present in the biocathodes."
1786272,Wyszkowski and  Radziemska 2013,Assessment of Tri- and Hexavalent Chromium Phytotoxicity on Oats (Avena sativa L.) Biomass and Content of Nitrogen Compounds,"The purpose of this study was to determine the effect of soil contamination with tri- and hexavalent chromium and soil application of compost, zeolite, and CaO on the mass of oats and content of nitrogen compounds in different organs of oats. The oats mass and content of nitrogen compounds in the crop depended on the type and dose of chromium and alleviating substances incorporated to soil. In the series without neutralizing substances, Cr(VI), unlike Cr(III), had a negative effect on the growth and development of oats. The highest doses of Cr(VI) and Cr(III) stimulated the accumulation of total nitrogen but depressed the content of N-NO3 (-) in most of organs of oats. Among the substances added to soil in order to alleviate the negative impact of Cr (VI) on the mass of plants, compost had a particularly beneficial effect on the growth and development of oats. The application of compost, zeolite, and CaO to soil had a stronger effect on the content of nitrogen compounds in grain and straw than in roots. Soil enrichment with either of the above substances usually raised the content of nitrogen compounds in oats grain and straw, but decreased it in roots.","Assessment of Tri- and Hexavalent Chromium Phytotoxicity on Oats (Avena sativa L.) Biomass and Content of Nitrogen Compounds Abs: The purpose of this study was to determine the effect of soil contamination with tri- and hexavalent chromium and soil application of compost, zeolite, and CaO on the mass of oats and content of nitrogen compounds in different organs of oats. The oats mass and content of nitrogen compounds in the crop depended on the type and dose of chromium and alleviating substances incorporated to soil. In the series without neutralizing substances, Cr(VI), unlike Cr(III), had a negative effect on the growth and development of oats. The highest doses of Cr(VI) and Cr(III) stimulated the accumulation of total nitrogen but depressed the content of N-NO3 (-) in most of organs of oats. Among the substances added to soil in order to alleviate the negative impact of Cr (VI) on the mass of plants, compost had a particularly beneficial effect on the growth and development of oats. The application of compost, zeolite, and CaO to soil had a stronger effect on the content of nitrogen compounds in grain and straw than in roots. Soil enrichment with either of the above substances usually raised the content of nitrogen compounds in oats grain and straw, but decreased it in roots."
1786271,Warshaw et al. 2013,North American Contact Dermatitis Group patch test results: 2009 to 2010,"<strong>BACKGROUND: </strong>Patch testing is an important diagnostic tool for determination of substances responsible for allergic contact dermatitis.<br /><br /><strong>OBJECTIVE: </strong>This study reports the North American Contact Dermatitis Group (NACDG) patch testing results from January 1, 2009, to December 31, 2010.<br /><br /><strong>METHODS: </strong>At 12 centers in North America, patients were tested in a standardized manner with a screening series of 70 allergens. Data were manually verified and entered into a central database. Descriptive frequencies were calculated, and trends were analyzed using ?2 statistics.<br /><br /><strong>RESULTS: </strong>A total of 4308 patients were tested. Of these, 2614 (60.7%) had at least 1 positive reaction, and 2284 (46.3%) were ultimately determined to have a primary diagnosis of allergic contact dermatitis. Four hundred twenty-seven (9.9%) patients had occupationally related skin disease. There were 6855 positive allergic reactions. As compared with the previous reporting period (2007-2008), the positive reaction rates statistically decreased for 20 allergens (nickel, neomycin, Myroxylon pereirae, cobalt, formaldehyde, quaternium 15, methydibromoglutaronitrile/phenoxyethanol, methylchlorisothiazolinone/methylisothiazolinone, potassium dichromate, diazolidinyl urea, propolis, dimethylol dimethylhydantoin, 2-bromo-2-nitro-1,3-propanediol, methyl methacrylate, ethyl acrylate, glyceryl thioglycolate, dibucaine, amidoamine, clobetasol, and dimethyloldihydroxyethyleneurea; P &lt; 0.05) and statistically increased for 4 allergens (fragrance mix II, iodopropynyl butylcarbamate, propylene glycol, and benzocaine; P &lt; 0.05). Approximately one quarter of tested patients had at least 1 relevant allergic reaction to a non-NACDG allergen. Hypothetically, approximately one quarter of reactions detected by NACDG allergens would have been missed by TRUE TEST (SmartPractice Denmark, Hillerød, Denmark).<br /><br /><strong>CONCLUSIONS: </strong>These results affirm the value of patch testing with many allergens.","North American Contact Dermatitis Group patch test results: 2009 to 2010 Abs: <strong>BACKGROUND: </strong>Patch testing is an important diagnostic tool for determination of substances responsible for allergic contact dermatitis.<br /><br /><strong>OBJECTIVE: </strong>This study reports the North American Contact Dermatitis Group (NACDG) patch testing results from January 1, 2009, to December 31, 2010.<br /><br /><strong>METHODS: </strong>At 12 centers in North America, patients were tested in a standardized manner with a screening series of 70 allergens. Data were manually verified and entered into a central database. Descriptive frequencies were calculated, and trends were analyzed using ?2 statistics.<br /><br /><strong>RESULTS: </strong>A total of 4308 patients were tested. Of these, 2614 (60.7%) had at least 1 positive reaction, and 2284 (46.3%) were ultimately determined to have a primary diagnosis of allergic contact dermatitis. Four hundred twenty-seven (9.9%) patients had occupationally related skin disease. There were 6855 positive allergic reactions. As compared with the previous reporting period (2007-2008), the positive reaction rates statistically decreased for 20 allergens (nickel, neomycin, Myroxylon pereirae, cobalt, formaldehyde, quaternium 15, methydibromoglutaronitrile/phenoxyethanol, methylchlorisothiazolinone/methylisothiazolinone, potassium dichromate, diazolidinyl urea, propolis, dimethylol dimethylhydantoin, 2-bromo-2-nitro-1,3-propanediol, methyl methacrylate, ethyl acrylate, glyceryl thioglycolate, dibucaine, amidoamine, clobetasol, and dimethyloldihydroxyethyleneurea; P &lt; 0.05) and statistically increased for 4 allergens (fragrance mix II, iodopropynyl butylcarbamate, propylene glycol, and benzocaine; P &lt; 0.05). Approximately one quarter of tested patients had at least 1 relevant allergic reaction to a non-NACDG allergen. Hypothetically, approximately one quarter of reactions detected by NACDG allergens would have been missed by TRUE TEST (SmartPractice Denmark, Hillerød, Denmark).<br /><br /><strong>CONCLUSIONS: </strong>These results affirm the value of patch testing with many allergens."
1786270,Wang et al. 2014,Association of folate deficiency and selected tumor marker concentrations in long-term hexavalent chromium exposed population,"Both hexavalent chromium [Cr (VI)] exposure and folate deficiency have been associated with increased cancer risks. Our previous studies have found folate deficiency in Cr (VI) exposed population. Here the relationship between some tumor markers and folate status in long-term Cr (VI) exposure was investigated carefully to show the multiple aspects of Cr (VI) carcinogenesis. A group of 115 workers occupationally exposed to chromate and 60 matched, unexposed controls in Shandong province of China were recruited. Environmental and biological exposure assessments including personal exposure to airborne Cr and Cr contents in erythrocytes were performed. Serum folate, plasma total homocysteine (tHcy) and plasma carcinoembryonic antigen (CEA), neuron specific enolase (NSE), squamous cell carcinoma antigen (SCC), cytokeratin fragment antigen 21-1 (CYFRA 21-1), cancer antigen 72-4 (CA72-4), as well as ?-fetoprotein (AFP) were measured. Smoking index (SI) was also calculated to discriminate possible confounding effects of smoking status. Serum folate level decreased significantly, while plasma tHcy, CEA, NSE, SCC, CYFRA21-1, CA72-4 and AFP concentrations increased significantly after Cr (VI) exposure. Meanwhile, plasma CEA, NSE and SCC were negatively correlated with serum folate. SI was negatively correlated with serum folate but positively correlated with plasma tHcy, CEA and NSE levels. Present study suggests that folate deficiency was associated with increased cancer risks and might be affected by smoking in Cr (VI) exposed population. Folate might play a key role in Cr (VI) carcinogenesis although further detailed investigations are needed to clarify the mechanism of this process.","Association of folate deficiency and selected tumor marker concentrations in long-term hexavalent chromium exposed population Abs: Both hexavalent chromium [Cr (VI)] exposure and folate deficiency have been associated with increased cancer risks. Our previous studies have found folate deficiency in Cr (VI) exposed population. Here the relationship between some tumor markers and folate status in long-term Cr (VI) exposure was investigated carefully to show the multiple aspects of Cr (VI) carcinogenesis. A group of 115 workers occupationally exposed to chromate and 60 matched, unexposed controls in Shandong province of China were recruited. Environmental and biological exposure assessments including personal exposure to airborne Cr and Cr contents in erythrocytes were performed. Serum folate, plasma total homocysteine (tHcy) and plasma carcinoembryonic antigen (CEA), neuron specific enolase (NSE), squamous cell carcinoma antigen (SCC), cytokeratin fragment antigen 21-1 (CYFRA 21-1), cancer antigen 72-4 (CA72-4), as well as ?-fetoprotein (AFP) were measured. Smoking index (SI) was also calculated to discriminate possible confounding effects of smoking status. Serum folate level decreased significantly, while plasma tHcy, CEA, NSE, SCC, CYFRA21-1, CA72-4 and AFP concentrations increased significantly after Cr (VI) exposure. Meanwhile, plasma CEA, NSE and SCC were negatively correlated with serum folate. SI was negatively correlated with serum folate but positively correlated with plasma tHcy, CEA and NSE levels. Present study suggests that folate deficiency was associated with increased cancer risks and might be affected by smoking in Cr (VI) exposed population. Folate might play a key role in Cr (VI) carcinogenesis although further detailed investigations are needed to clarify the mechanism of this process."
1786269,Wang et al. 2013,Efficient photocatalytic reduction of aqueous Cr(VI) over flower-like SnIn4S8 microspheres under visible light illumination,"Photocatalytic reduction of aqueous Cr(VI) was successfully achieved on nanostructured SnIn(4)S(8). The SnIn(4)S(8) particles with flower-like nanostructure were synthesized via a facile solvothermal method. UV-vis diffuse reflectance spectra (DRS) indicated that the SnIn(4)S(8) particles had strong absorption in visible region and the band gap was estimated to be from 2.27 to 2.35 eV. The photocatalytic reduction of aqueous Cr(VI) by flower-like SnIn(4)S(8) was evaluated under visible light (?&gt;400 nm) irradiation. The polyvinyl pyrrolidone (PVP) assisted SnIn(4)S(8) sample exhibits excellent removal efficiency of Cr(VI) (~97%) and good photocatalytic stability. The predominant photocatalytic activity is due to its large surface area, strong absorption in visible-light region and excellent charge separation characteristics.","Efficient photocatalytic reduction of aqueous Cr(VI) over flower-like SnIn4S8 microspheres under visible light illumination Abs: Photocatalytic reduction of aqueous Cr(VI) was successfully achieved on nanostructured SnIn(4)S(8). The SnIn(4)S(8) particles with flower-like nanostructure were synthesized via a facile solvothermal method. UV-vis diffuse reflectance spectra (DRS) indicated that the SnIn(4)S(8) particles had strong absorption in visible region and the band gap was estimated to be from 2.27 to 2.35 eV. The photocatalytic reduction of aqueous Cr(VI) by flower-like SnIn(4)S(8) was evaluated under visible light (?&gt;400 nm) irradiation. The polyvinyl pyrrolidone (PVP) assisted SnIn(4)S(8) sample exhibits excellent removal efficiency of Cr(VI) (~97%) and good photocatalytic stability. The predominant photocatalytic activity is due to its large surface area, strong absorption in visible-light region and excellent charge separation characteristics."
1786268,Wadhawan et al. ,Biogeochemical Controls on Hexavalent Chromium Formation in Estuarine Sediments,"Predicting the aquatic and human health impacts of chromium (Cr) necessitates one to determine its speciation as either relatively nontoxic Cr(III) or toxic Cr(VI) and elucidate the influence of biogeochemical changes on its behavior and fate. In the Baltimore Harbor, Cr predominantly exists as Cr(III) associated with sediments. While reduction of Cr(VI) to Cr(III) is dominant in these anoxic sediments, the potential of Cr(III) oxidation and Cr(VI) reoccurrence during sediment resuspension and oxygenation resulting from dredging, bioturbation, and flood events poses a serious concern. In batch experiments, aqueous Cr(VI) spiked into continuously mixed anoxic suspensions was reduced to product Cr(III) under anaerobic conditions. No Cr(VI) reoccurrence was observed when conditions remained anaerobic. Aeration caused Cr(VI) reoccurrence from the abiotic oxidation of product Cr(III). Rates of aeration-driven Cr(VI) reoccurrence increased with pH, and Cr(VI) reoccurrence positively correlated with dissolved manganese (Mn) decline at pH ? 7. Aeration-driven oxidation of Mn(II) to Mn(III,IV)(hydr)oxides was the underlying mechanism causing product Cr(III) oxidation. Cr(VI) reoccurrence decreased with sediment loading and negatively correlated with the acid volatile sulfide (AVS) concentration. Although sediment resuspension and oxygenation may create temporary conditions conducive to Cr(VI) formation, long-term Cr(VI) persistence is unlikely in the presence of sediment reductants. While such natural attenuation in reducing environments mitigates the risk associated with Cr toxicity, this risk may still persist in Mn-rich and reductant-deficient environments.","Biogeochemical Controls on Hexavalent Chromium Formation in Estuarine Sediments Abs: Predicting the aquatic and human health impacts of chromium (Cr) necessitates one to determine its speciation as either relatively nontoxic Cr(III) or toxic Cr(VI) and elucidate the influence of biogeochemical changes on its behavior and fate. In the Baltimore Harbor, Cr predominantly exists as Cr(III) associated with sediments. While reduction of Cr(VI) to Cr(III) is dominant in these anoxic sediments, the potential of Cr(III) oxidation and Cr(VI) reoccurrence during sediment resuspension and oxygenation resulting from dredging, bioturbation, and flood events poses a serious concern. In batch experiments, aqueous Cr(VI) spiked into continuously mixed anoxic suspensions was reduced to product Cr(III) under anaerobic conditions. No Cr(VI) reoccurrence was observed when conditions remained anaerobic. Aeration caused Cr(VI) reoccurrence from the abiotic oxidation of product Cr(III). Rates of aeration-driven Cr(VI) reoccurrence increased with pH, and Cr(VI) reoccurrence positively correlated with dissolved manganese (Mn) decline at pH ? 7. Aeration-driven oxidation of Mn(II) to Mn(III,IV)(hydr)oxides was the underlying mechanism causing product Cr(III) oxidation. Cr(VI) reoccurrence decreased with sediment loading and negatively correlated with the acid volatile sulfide (AVS) concentration. Although sediment resuspension and oxygenation may create temporary conditions conducive to Cr(VI) formation, long-term Cr(VI) persistence is unlikely in the presence of sediment reductants. While such natural attenuation in reducing environments mitigates the risk associated with Cr toxicity, this risk may still persist in Mn-rich and reductant-deficient environments."
1786267,Volpe et al. 2013,Simultaneous Cr(VI) reduction and non-ionic surfactant oxidation by peroxymonosulphate and iron powder,"Some industrial wastewaters contain both hexavalent chromium and surfactants. In this work, their removal from aqueous solution by zero-valent iron (ZVI) and peroxymonosulphate (PMS) was studied using Brij 35 as a representative non-ionic surfactant. The performance of the ZVI/PMS system in the simultaneous removal of both pollutants was compared to that achieved with control solutions containing either Cr(VI) or Brij 35 separately. Reactions were carried out over 24h at initial pH=2.3 with variable initial amounts of Cr(VI) and Brij 35. The results showed that surfactant removal was enhanced in the system also containing Cr(VI). Surfactant degradation followed zero-order kinetics and produced formic acid as the main by-product, together with hydroxylated aldehydes, formates and alcohols that were identified by LC/MS. The presence of surfactant similarly enhanced Cr(VI) reduction, which also followed zero-order kinetics. Chromium removal was quantitative only when the initial chromium concentration was lower than 140 mg L(-1). Reduced chromium was mainly in the solution phase together with dissolved iron. Precipitation with NaOH was therefore required to definitively remove dissolved metals from the investigated system.","Simultaneous Cr(VI) reduction and non-ionic surfactant oxidation by peroxymonosulphate and iron powder Abs: Some industrial wastewaters contain both hexavalent chromium and surfactants. In this work, their removal from aqueous solution by zero-valent iron (ZVI) and peroxymonosulphate (PMS) was studied using Brij 35 as a representative non-ionic surfactant. The performance of the ZVI/PMS system in the simultaneous removal of both pollutants was compared to that achieved with control solutions containing either Cr(VI) or Brij 35 separately. Reactions were carried out over 24h at initial pH=2.3 with variable initial amounts of Cr(VI) and Brij 35. The results showed that surfactant removal was enhanced in the system also containing Cr(VI). Surfactant degradation followed zero-order kinetics and produced formic acid as the main by-product, together with hydroxylated aldehydes, formates and alcohols that were identified by LC/MS. The presence of surfactant similarly enhanced Cr(VI) reduction, which also followed zero-order kinetics. Chromium removal was quantitative only when the initial chromium concentration was lower than 140 mg L(-1). Reduced chromium was mainly in the solution phase together with dissolved iron. Precipitation with NaOH was therefore required to definitively remove dissolved metals from the investigated system."
1786266,Viradia and  Vala ,"In silico Protein Structure Modeling and Conservation Analysis of ChrR, a Class-I Chromate Reducing Flavoenzyme from Pseudomonas putida","Hexavalent chromium [Cr(VI)] is a widespread environmental pollutant, arising as a by-product of numerous industrial processes. Bacteria can reduce toxic and carcinogenic Cr(VI) to insoluble and less toxic Cr(III), offering promise for an environmental friendly and affordable solution to chromate pollution. ChrR, a class I chromate-reducing flavoenzyme from Pseudomonas putida is an efficient chromate reducer. The crystal structure of ChrR is yet unknown to the scientific community, hence a three-dimensional (3D) structure is very essential for structural studies, protein - ligand interaction simulations and designing novel bioremediation strategies. The 3D model of the P. putida ChrR protein was predicted using in silico approach. Due to low percentage of sequence identity for homology modeling, I-TASSER was used for structure prediction which combines the methods of threading, ab initio modeling and structural refinement. The stereo chemical quality of the best model was validated with 90.6% residues under favored region from Ramachandran plot. The modeled protein was submitted to Protein Model Database and can be downloaded with the ID PM0077375. The degree of conservation was mapped onto the predicted model and ligand binding sites were found. The results of conservation analysis and binding site prediction were combined to show several highly conserved binding sites. Altogether, the structure for ChrR has been predicted. The work reveals novel universally conserved residues. These residues could be candidates for binding interactions and provide the basis for designing advanced chromium bioremediation strategies.","In silico Protein Structure Modeling and Conservation Analysis of ChrR, a Class-I Chromate Reducing Flavoenzyme from Pseudomonas putida Abs: Hexavalent chromium [Cr(VI)] is a widespread environmental pollutant, arising as a by-product of numerous industrial processes. Bacteria can reduce toxic and carcinogenic Cr(VI) to insoluble and less toxic Cr(III), offering promise for an environmental friendly and affordable solution to chromate pollution. ChrR, a class I chromate-reducing flavoenzyme from Pseudomonas putida is an efficient chromate reducer. The crystal structure of ChrR is yet unknown to the scientific community, hence a three-dimensional (3D) structure is very essential for structural studies, protein - ligand interaction simulations and designing novel bioremediation strategies. The 3D model of the P. putida ChrR protein was predicted using in silico approach. Due to low percentage of sequence identity for homology modeling, I-TASSER was used for structure prediction which combines the methods of threading, ab initio modeling and structural refinement. The stereo chemical quality of the best model was validated with 90.6% residues under favored region from Ramachandran plot. The modeled protein was submitted to Protein Model Database and can be downloaded with the ID PM0077375. The degree of conservation was mapped onto the predicted model and ligand binding sites were found. The results of conservation analysis and binding site prediction were combined to show several highly conserved binding sites. Altogether, the structure for ChrR has been predicted. The work reveals novel universally conserved residues. These residues could be candidates for binding interactions and provide the basis for designing advanced chromium bioremediation strategies."
1786265,Velma and  Tchounwou 2013,"Oxidative Stress and DNA Damage Induced by Chromium in Liver and Kidney of Goldfish, Carassius auratus","Chromium (Cr) is an abundant element in the Earth's crust. It exhibits various oxidation states, from divalent to hexavalent forms. Cr has diverse applications in various industrial processes and inadequate treatment of the industrial effluents leads to the contamination of the surrounding water resources. Hexavalent chromium (Cr (VI)) is the most toxic form, and its toxicity has been associated with oxidative stress. The present study was designed to investigate the toxic potential of Cr (VI) in fish. In this research, we investigated the role of oxidative stress in chromium-induced genotoxicity in the liver and kidney cells of goldfish, Carassius auratus. Goldfish were acclimatized to the laboratory conditions and exposed them to 5% and 10% of 96 hr-LC50 (85.7 mg/L) of aqueous Cr (VI) in a continuous flow through system. Fish were sampled every 7 days for a period of 28 days to analyze the lipid hydroperoxides (LHP) levels and genotoxic potentials in the liver and kidney. LHP levels were analyzed by spectrophotometry while genotoxicity was assessed by single cell gel electrophoresis (comet) assay. LHP levels in the liver increased significantly at week 1, followed by a decrease. LHP levels in the kidney increased significantly at weeks 1, 2, and 3, and decreased at week 4 compared to the control. The percentage of DNA damage increased in both liver and kidney at both test concentrations. The results clearly indicate that Cr (VI) induces significant levels of DNA damage in liver and kidney cells of goldfish. The induced LHP levels in both organs were concentration-dependent and were directly correlated with the levels of DNA damage. The two tested Cr (VI) concentrations induced significant levels of oxidative stress in both organs, however the kidney appears to be more vulnerable and sensitive to Cr-induced toxicity than the liver.","Oxidative Stress and DNA Damage Induced by Chromium in Liver and Kidney of Goldfish, Carassius auratus Abs: Chromium (Cr) is an abundant element in the Earth's crust. It exhibits various oxidation states, from divalent to hexavalent forms. Cr has diverse applications in various industrial processes and inadequate treatment of the industrial effluents leads to the contamination of the surrounding water resources. Hexavalent chromium (Cr (VI)) is the most toxic form, and its toxicity has been associated with oxidative stress. The present study was designed to investigate the toxic potential of Cr (VI) in fish. In this research, we investigated the role of oxidative stress in chromium-induced genotoxicity in the liver and kidney cells of goldfish, Carassius auratus. Goldfish were acclimatized to the laboratory conditions and exposed them to 5% and 10% of 96 hr-LC50 (85.7 mg/L) of aqueous Cr (VI) in a continuous flow through system. Fish were sampled every 7 days for a period of 28 days to analyze the lipid hydroperoxides (LHP) levels and genotoxic potentials in the liver and kidney. LHP levels were analyzed by spectrophotometry while genotoxicity was assessed by single cell gel electrophoresis (comet) assay. LHP levels in the liver increased significantly at week 1, followed by a decrease. LHP levels in the kidney increased significantly at weeks 1, 2, and 3, and decreased at week 4 compared to the control. The percentage of DNA damage increased in both liver and kidney at both test concentrations. The results clearly indicate that Cr (VI) induces significant levels of DNA damage in liver and kidney cells of goldfish. The induced LHP levels in both organs were concentration-dependent and were directly correlated with the levels of DNA damage. The two tested Cr (VI) concentrations induced significant levels of oxidative stress in both organs, however the kidney appears to be more vulnerable and sensitive to Cr-induced toxicity than the liver."
1786264,Vaquero et al. 2013,Activation of the nuclear receptor FXR enhances hepatocyte chemoprotection and liver tumor chemoresistance against genotoxic compounds,"The success of pharmacological treatments in primary liver cancers is limited by the marked efficacy of mechanisms of chemoresistance already present in hepatocytes. The role of the nuclear receptor FXR is unclear. Although, in non-treated liver tumors, its expression is reduced, the refractoriness to anticancer drugs is high. Moreover, the treatment with cisplatin up-regulates FXR. The aim of this study was to investigate whether FXR is involved in stimulating chemoprotection/chemoresistance in healthy and tumor liver cells. In human hepatocytes, the activation of FXR with the agonist GW4064 resulted in a significant protection against cisplatin-induced toxicity. In human hepatoma Alexander cells, with negligible endogenous expression of FXR, GW4064 also protected against cisplatin-induced toxicity, but only if they were previously transfected with FXR/RXR. Investigation of 109 genes potentially involved in chemoresistance revealed that only ABCB4, TCEA2, CCL14, CCL15 and KRT13 were up-regulated by FXR activation both in human hepatocytes and FXR/RXR-expressing hepatoma cells. In both models, cisplatin, even in the absence of FXR agonists, such as bile acids and GW4064, was able to up-regulate FXR targets genes, which was due to FXR-mediated trans-activation of response elements in the promoter region. FXR-dependent chemoprotection was also efficient against other DNA-damaging compounds, such as doxorubicin, mitomycin C and potassium dichromate, but not against non-genotoxic drugs, such as colchicine, paclitaxel, acetaminophen, artesunate and sorafenib. In conclusion, ligand-dependent and independent activation of FXR stimulates mechanisms able to enhance the chemoprotection of hepatocytes against genotoxic compounds and to reduce the response of liver tumor cells to certain pharmacological treatments.","Activation of the nuclear receptor FXR enhances hepatocyte chemoprotection and liver tumor chemoresistance against genotoxic compounds Abs: The success of pharmacological treatments in primary liver cancers is limited by the marked efficacy of mechanisms of chemoresistance already present in hepatocytes. The role of the nuclear receptor FXR is unclear. Although, in non-treated liver tumors, its expression is reduced, the refractoriness to anticancer drugs is high. Moreover, the treatment with cisplatin up-regulates FXR. The aim of this study was to investigate whether FXR is involved in stimulating chemoprotection/chemoresistance in healthy and tumor liver cells. In human hepatocytes, the activation of FXR with the agonist GW4064 resulted in a significant protection against cisplatin-induced toxicity. In human hepatoma Alexander cells, with negligible endogenous expression of FXR, GW4064 also protected against cisplatin-induced toxicity, but only if they were previously transfected with FXR/RXR. Investigation of 109 genes potentially involved in chemoresistance revealed that only ABCB4, TCEA2, CCL14, CCL15 and KRT13 were up-regulated by FXR activation both in human hepatocytes and FXR/RXR-expressing hepatoma cells. In both models, cisplatin, even in the absence of FXR agonists, such as bile acids and GW4064, was able to up-regulate FXR targets genes, which was due to FXR-mediated trans-activation of response elements in the promoter region. FXR-dependent chemoprotection was also efficient against other DNA-damaging compounds, such as doxorubicin, mitomycin C and potassium dichromate, but not against non-genotoxic drugs, such as colchicine, paclitaxel, acetaminophen, artesunate and sorafenib. In conclusion, ligand-dependent and independent activation of FXR stimulates mechanisms able to enhance the chemoprotection of hepatocytes against genotoxic compounds and to reduce the response of liver tumor cells to certain pharmacological treatments."
1786263,Tiwari et al. ,Chromium Phytotoxicity in Radish (Raphanus sativus): Effects on Metabolism and Nutrient Uptake,"In the present investigation, chromium (VI) induced toxicity on metabolic activity and translocations of nutrients in radish were evaluated under controlled glass house conditions. Chromium was found to induce toxicity and significantly affect plant growth and metabolic activity. Excess of chromium (0.4 mM) caused a decrease in the concentration of iron in leaves (from 134.3 to 71.9 ?g g(-1) dw) and significant translocation of sulphur, phosphorus and zinc. Translocation of manganese, copper and boron were less affected from root to stem. After 15 days of Cr exposure, maximum accumulation of Cr was found in roots (327.6 ?g g(-1) dw) followed by stems (186.8 ?g g(-1) dw) and leaves (116.7 ?g g(-1) dw) at 0.4 mM Cr concentration. Therefore, Cr may affect negatively not only production, but also the nutritive quality of the radish; likewise, higher Cr content may cause health hazards for humans.","Chromium Phytotoxicity in Radish (Raphanus sativus): Effects on Metabolism and Nutrient Uptake Abs: In the present investigation, chromium (VI) induced toxicity on metabolic activity and translocations of nutrients in radish were evaluated under controlled glass house conditions. Chromium was found to induce toxicity and significantly affect plant growth and metabolic activity. Excess of chromium (0.4 mM) caused a decrease in the concentration of iron in leaves (from 134.3 to 71.9 ?g g(-1) dw) and significant translocation of sulphur, phosphorus and zinc. Translocation of manganese, copper and boron were less affected from root to stem. After 15 days of Cr exposure, maximum accumulation of Cr was found in roots (327.6 ?g g(-1) dw) followed by stems (186.8 ?g g(-1) dw) and leaves (116.7 ?g g(-1) dw) at 0.4 mM Cr concentration. Therefore, Cr may affect negatively not only production, but also the nutritive quality of the radish; likewise, higher Cr content may cause health hazards for humans."
1786262,Thompson et al. 2013,Assessment of the mode of action underlying development of rodent small intestinal tumors following oral exposure to hexavalent chromium and relevance to humans,"Abstract Chronic exposure to high concentrations of hexavalent chromium (Cr(VI)) in drinking water causes intestinal adenomas and carcinomas in mice, but not in rats. Cr(VI) causes damage to intestinal villi and crypt hyperplasia in mice after only one week of exposure. After two years of exposure, intestinal damage and crypt hyperplasia are evident in mice (but not rats), as are intestinal tumors. Although Cr(VI) has genotoxic properties, these findings suggest that intestinal tumors in mice arise as a result of chronic mucosal injury. To better understand the mode of action (MOA) of Cr(VI) in the intestine, a 90-day drinking water study was conducted to collect histological, biochemical, toxicogenomic and pharmacokinetic data in intestinal tissues. Using MOA analyses and human relevance frameworks proposed by national and international regulatory agencies, the weight of evidence supports a cytotoxic MOA with the following key events: (a) absorption of Cr(VI) from the intestinal lumen, (b) toxicity to intestinal villi, (c) crypt regenerative hyperplasia and (d) clonal expansion of mutations within the crypt stem cells, resulting in late onset tumorigenesis. This article summarizes the data supporting each key event in the MOA, as well as data that argue against a mutagenic MOA for Cr(VI)-induced intestinal tumors.","Assessment of the mode of action underlying development of rodent small intestinal tumors following oral exposure to hexavalent chromium and relevance to humans Abs: Abstract Chronic exposure to high concentrations of hexavalent chromium (Cr(VI)) in drinking water causes intestinal adenomas and carcinomas in mice, but not in rats. Cr(VI) causes damage to intestinal villi and crypt hyperplasia in mice after only one week of exposure. After two years of exposure, intestinal damage and crypt hyperplasia are evident in mice (but not rats), as are intestinal tumors. Although Cr(VI) has genotoxic properties, these findings suggest that intestinal tumors in mice arise as a result of chronic mucosal injury. To better understand the mode of action (MOA) of Cr(VI) in the intestine, a 90-day drinking water study was conducted to collect histological, biochemical, toxicogenomic and pharmacokinetic data in intestinal tissues. Using MOA analyses and human relevance frameworks proposed by national and international regulatory agencies, the weight of evidence supports a cytotoxic MOA with the following key events: (a) absorption of Cr(VI) from the intestinal lumen, (b) toxicity to intestinal villi, (c) crypt regenerative hyperplasia and (d) clonal expansion of mutations within the crypt stem cells, resulting in late onset tumorigenesis. This article summarizes the data supporting each key event in the MOA, as well as data that argue against a mutagenic MOA for Cr(VI)-induced intestinal tumors."
1786261,Sun et al. 2013,Preparation and characterization of TiO2/acid leached serpentinite tailings composites and their photocatalytic reduction of Chromium(VI),"Composite TiO2/acid leached serpentine tailings (AST) were synthesized through the hydrolysis-deposition method and characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), energy-dispersive X-ray spectrometry (EDS), Fourier-transform infrared spectroscopy (FT-IR), transmission electron microscopy (TEM), X-ray photoelectron spectroscopy (XPS), and surface area measurement (BET). The XRD analysis showed that TiO2 coated on the surface of acid leached serpentine tailings was mixed crystal phases of rutile and anatase, the grain size of which is 10-30nm. SEM, TEM, and EDS analysis exhibited that nano-TiO2 particles were deposited on the surface and internal cavities of acid leaching serpentine tailings. The XPS and FT-IR analysis demonstrated that the coating process of TiO2 on AST was a physical adsorption process. The large specific surface area, porous structure, and plentiful surface hydroxyl group of TiO2/AST composite resulted in the high adsorption capacity of Cr(VI). The experimental results demonstrated that initial concentration of Cr(VI), the amount of the catalyst, and pH greatly influenced the removal efficiency of Cr(VI). The removal kinetics of Cr(VI) at a relative low initial concentration was fitted well with Langmuir-Hinshelwood kinetics model with R(2) value of about unity. The as-prepared composites exhibited strong adsorption and photocatalytic capacity for the removal of Cr(VI), and the possible photocatalytic reduction mechanism was studied. The photodecomposition of Cr(VI) was as high as 95% within 2h, and the reusability of the photocatalysis was proven.","Preparation and characterization of TiO2/acid leached serpentinite tailings composites and their photocatalytic reduction of Chromium(VI) Abs: Composite TiO2/acid leached serpentine tailings (AST) were synthesized through the hydrolysis-deposition method and characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), energy-dispersive X-ray spectrometry (EDS), Fourier-transform infrared spectroscopy (FT-IR), transmission electron microscopy (TEM), X-ray photoelectron spectroscopy (XPS), and surface area measurement (BET). The XRD analysis showed that TiO2 coated on the surface of acid leached serpentine tailings was mixed crystal phases of rutile and anatase, the grain size of which is 10-30nm. SEM, TEM, and EDS analysis exhibited that nano-TiO2 particles were deposited on the surface and internal cavities of acid leaching serpentine tailings. The XPS and FT-IR analysis demonstrated that the coating process of TiO2 on AST was a physical adsorption process. The large specific surface area, porous structure, and plentiful surface hydroxyl group of TiO2/AST composite resulted in the high adsorption capacity of Cr(VI). The experimental results demonstrated that initial concentration of Cr(VI), the amount of the catalyst, and pH greatly influenced the removal efficiency of Cr(VI). The removal kinetics of Cr(VI) at a relative low initial concentration was fitted well with Langmuir-Hinshelwood kinetics model with R(2) value of about unity. The as-prepared composites exhibited strong adsorption and photocatalytic capacity for the removal of Cr(VI), and the possible photocatalytic reduction mechanism was studied. The photodecomposition of Cr(VI) was as high as 95% within 2h, and the reusability of the photocatalysis was proven."
1786260,Street and  Cele 2013,Commonly used metal and crystalline salts in South African traditional medicine,"<strong>ETHNOPHARMACOLOGICAL RELEVANCE: </strong>Traditional medicines in the form of plants, animals and/or minerals are used by millions of South Africans. There is currently no data regarding the commonly used mineral elements thus the potential benefits or hazards of such products remain unclear.<br /><br /><strong>MATERIALS AND METHODS: </strong>Metal and crystalline salts were purchased from a rural market (Nongoma, Zululand, South Africa). Information regarding the colloquial name, price and weight was recorded. Energy dispersive X-ray spectroscopy (EDX) was used to quantatively determine the unknown salts.<br /><br /><strong>RESULTS: </strong>Six widely available salts were analyzed. Ndonya, as it is colloquially known, refers to two products which look identical to the untrained eye-one is dyed table salt and the other is hexavalent chromium. A further product used medicinally, although not widely available, was identified as iron chromite ore.<br /><br /><strong>CONCLUSIONS: </strong>The array of substances documented, ranging from benign to carcinogenic, stresses the importance of documenting components used in traditional medicine and confirms the necessity to regulate South Africa traditional medicine. Healthcare workers should be aware of the complexities of using such metal salt.","Commonly used metal and crystalline salts in South African traditional medicine Abs: <strong>ETHNOPHARMACOLOGICAL RELEVANCE: </strong>Traditional medicines in the form of plants, animals and/or minerals are used by millions of South Africans. There is currently no data regarding the commonly used mineral elements thus the potential benefits or hazards of such products remain unclear.<br /><br /><strong>MATERIALS AND METHODS: </strong>Metal and crystalline salts were purchased from a rural market (Nongoma, Zululand, South Africa). Information regarding the colloquial name, price and weight was recorded. Energy dispersive X-ray spectroscopy (EDX) was used to quantatively determine the unknown salts.<br /><br /><strong>RESULTS: </strong>Six widely available salts were analyzed. Ndonya, as it is colloquially known, refers to two products which look identical to the untrained eye-one is dyed table salt and the other is hexavalent chromium. A further product used medicinally, although not widely available, was identified as iron chromite ore.<br /><br /><strong>CONCLUSIONS: </strong>The array of substances documented, ranging from benign to carcinogenic, stresses the importance of documenting components used in traditional medicine and confirms the necessity to regulate South Africa traditional medicine. Healthcare workers should be aware of the complexities of using such metal salt."
1786259,Stanley et al. ,Postnatal exposure to chromium through mother's milk accelerates follicular atresia in F1 offspring through increased oxidative stress and depletion of antioxidant enzymes,"Hexavalent chromium, CrVI, is a heavy metal endocrine disruptor, known as a mutagen, teratogen, and a group A carcinogen. Environmental contamination with CrVI, including drinking water, has been increasing in more than 30 cities in the United States. CrVI is rapidly converted to CrIII intracellularly, and CrIII can cause DNA strand breaks and cancer or apoptosis through different mechanisms. Our previous study demonstrated that lactational exposure to chromium results in a delay or arrest in follicle development and a decrease in steroid hormone levels in F1 female rats, both of which are mitigated (partial inhibition) by vitamin C. The current study tested the hypothesis that lactational exposure to CrIII accelerates follicle atresia in F1 offspring by increasing reactive oxygen species (ROS) and decreasing cellular antioxidants. Results showed that lactational exposure to CrIII dose-dependently increased follicular atresia and decreased steroidogenesis in postnatal day 25, 45, and 65 rats. Vitamin C mitigated or inhibited the effects of CrIII at all doses. CrIII increased hydrogen peroxide and lipid hydroperoxide in plasma and ovary; decreased the antioxidant enzymes (AOXs) GPx1, GR, SOD, and catalase; and increased glutathione S-transferase in plasma and ovary. To understand the effects of CrVI on ROS and AOXs in granulosa (GC) and theca (TC) cell compartments in the ovary, ROS levels and mRNA expression of cytosolic and mitochondrial AOXs, such as SOD1, SOD2, catalase, GLRX1, GSTM1, GSTM2, GSTA4, GR, TXN1, TXN2, TXNRD2, and PRDX3, were studied in GCs and TCs and in a spontaneously immortalized granulosa cell line (SIGC). Overall, CrVI downregulated each of the AOXs; and vitamin C mitigated the effects of CrVI on these enzymes in GCs and SIGCs, but failed to mitigate CrVI effects on GSTM1, GSTM2, TXN1, and TXN2 in TCs. Thus, these data for the first time reveal that lactational exposure to CrIII accelerated follicular atresia and decreased steroidogenesis in F1 female offspring by altering the ratio of ROS and AOXs in the ovary. Vitamin C is able to protect the ovary from CrIII-induced oxidative stress and follicle atresia through protective effects on GCs rather than TCs.","Postnatal exposure to chromium through mother's milk accelerates follicular atresia in F1 offspring through increased oxidative stress and depletion of antioxidant enzymes Abs: Hexavalent chromium, CrVI, is a heavy metal endocrine disruptor, known as a mutagen, teratogen, and a group A carcinogen. Environmental contamination with CrVI, including drinking water, has been increasing in more than 30 cities in the United States. CrVI is rapidly converted to CrIII intracellularly, and CrIII can cause DNA strand breaks and cancer or apoptosis through different mechanisms. Our previous study demonstrated that lactational exposure to chromium results in a delay or arrest in follicle development and a decrease in steroid hormone levels in F1 female rats, both of which are mitigated (partial inhibition) by vitamin C. The current study tested the hypothesis that lactational exposure to CrIII accelerates follicle atresia in F1 offspring by increasing reactive oxygen species (ROS) and decreasing cellular antioxidants. Results showed that lactational exposure to CrIII dose-dependently increased follicular atresia and decreased steroidogenesis in postnatal day 25, 45, and 65 rats. Vitamin C mitigated or inhibited the effects of CrIII at all doses. CrIII increased hydrogen peroxide and lipid hydroperoxide in plasma and ovary; decreased the antioxidant enzymes (AOXs) GPx1, GR, SOD, and catalase; and increased glutathione S-transferase in plasma and ovary. To understand the effects of CrVI on ROS and AOXs in granulosa (GC) and theca (TC) cell compartments in the ovary, ROS levels and mRNA expression of cytosolic and mitochondrial AOXs, such as SOD1, SOD2, catalase, GLRX1, GSTM1, GSTM2, GSTA4, GR, TXN1, TXN2, TXNRD2, and PRDX3, were studied in GCs and TCs and in a spontaneously immortalized granulosa cell line (SIGC). Overall, CrVI downregulated each of the AOXs; and vitamin C mitigated the effects of CrVI on these enzymes in GCs and SIGCs, but failed to mitigate CrVI effects on GSTM1, GSTM2, TXN1, and TXN2 in TCs. Thus, these data for the first time reveal that lactational exposure to CrIII accelerated follicular atresia and decreased steroidogenesis in F1 female offspring by altering the ratio of ROS and AOXs in the ovary. Vitamin C is able to protect the ovary from CrIII-induced oxidative stress and follicle atresia through protective effects on GCs rather than TCs."
1786258,Soni et al. 2013,In vitro Cr(VI) reduction by cell-free extracts of chromate-reducing bacteria isolated from tannery effluent irrigated soil,"Four efficient Cr(VI)-reducing bacterial strains were isolated from rhizospheric soil of plants irrigated with tannery effluent and investigated for in vitro Cr(VI) reduction. Based on 16S rRNA gene sequencing, the isolated strains SUCR44, SUCR140, SUCR186, and SUCR188 were identified as Bacillus sp. (JN674188), Microbacterium sp. (JN674183), Bacillus thuringiensis (JN674184), and Bacillus subtilis (JN674195), respectively. All four isolates could completely reduce Cr(VI) in culture media at 0.2 mM concentration within a period of 24-120 h; SUCR140 completely reduced Cr(VI) within 24 h. Assay with the permeabilized cells (treated with Triton X-100 and Tween 80) and cell-free assay demonstrated that the Cr(VI) reduction activity was mainly associated with the soluble fraction of cells. Considering the major amount of chromium being reduced within 24-48 h, these fractions could have been released extracellularly also during their growth. At the temperature optima of 28 °C and pH 7.0, the specific activity of Cr(VI) reduction was determined to be 0.32, 0.42, 0.34, and 0.28 ?mol Cr(VI)min(-1)mg(-1) protein for isolates SUCR44, SUCR140, SUCR186, and SUCR188, respectively. Addition of 0.1 mM NADH enhanced the Cr(VI) reduction in the cell-free extracts of all four strains. The Cr(VI) reduction activity in cell-free extracts of all the isolates was stable in presence of different metal ions tested except Hg(2+). Beside this, urea and thiourea also reduced the activity of chromate reduction to significant levels.","In vitro Cr(VI) reduction by cell-free extracts of chromate-reducing bacteria isolated from tannery effluent irrigated soil Abs: Four efficient Cr(VI)-reducing bacterial strains were isolated from rhizospheric soil of plants irrigated with tannery effluent and investigated for in vitro Cr(VI) reduction. Based on 16S rRNA gene sequencing, the isolated strains SUCR44, SUCR140, SUCR186, and SUCR188 were identified as Bacillus sp. (JN674188), Microbacterium sp. (JN674183), Bacillus thuringiensis (JN674184), and Bacillus subtilis (JN674195), respectively. All four isolates could completely reduce Cr(VI) in culture media at 0.2 mM concentration within a period of 24-120 h; SUCR140 completely reduced Cr(VI) within 24 h. Assay with the permeabilized cells (treated with Triton X-100 and Tween 80) and cell-free assay demonstrated that the Cr(VI) reduction activity was mainly associated with the soluble fraction of cells. Considering the major amount of chromium being reduced within 24-48 h, these fractions could have been released extracellularly also during their growth. At the temperature optima of 28 °C and pH 7.0, the specific activity of Cr(VI) reduction was determined to be 0.32, 0.42, 0.34, and 0.28 ?mol Cr(VI)min(-1)mg(-1) protein for isolates SUCR44, SUCR140, SUCR186, and SUCR188, respectively. Addition of 0.1 mM NADH enhanced the Cr(VI) reduction in the cell-free extracts of all four strains. The Cr(VI) reduction activity in cell-free extracts of all the isolates was stable in presence of different metal ions tested except Hg(2+). Beside this, urea and thiourea also reduced the activity of chromate reduction to significant levels."
1786257,Sitko et al. 2013,Adsorption of divalent metal ions from aqueous solutions using graphene oxide,"The adsorptive properties of graphene oxide (GO) towards divalent metal ions (copper, zinc, cadmium and lead) were investigated. GO prepared through the oxidation of graphite using potassium dichromate was characterized by scanning electron microscopy (SEM), powder X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS) and infrared spectroscopy (FT-IR). The results of batch experiments and measurements by flame atomic absorption spectrometry (F-AAS) indicate that maximum adsorption can be achieved in broad pH ranges: 3-7 for Cu(II), 5-8 for Zn(II), 4-8 for Cd(II), 3-7 for Pb(II). The maximum adsorption capacities of Cu(II), Zn(II), Cd(II) and Pb(II) on GO at pH = 5 are 294, 345, 530, 1119 mg g(-1), respectively. The competitive adsorption experiments showed the affinity in the order of Pb(II) &gt; Cu(II) ? Cd(II) &gt; Zn(II). Adsorption isotherms and kinetic studies suggest that sorption of metal ions on GO nanosheets is monolayer coverage and adsorption is controlled by chemical adsorption involving the strong surface complexation of metal ions with the oxygen-containing groups on the surface of GO. Chemisorption was confirmed by XPS (binding energy and shape of O1s and C1s peaks) of GO with adsorbed metal ions. The adsorption experiments show that the dispersibility of GO in water changes remarkably after complexation of metal ions. After adsorption, the tendency to agglomerate and precipitate is observed. Excellent dispersibility of GO and strong tendency of GO-Me(II) to precipitate open the path to removal of heavy metals from water solution. Potential application of GO in analytical chemistry as a solid sorbent for preconcentration of trace elements and in heavy metal ion pollution cleanup results from its maximum adsorption capacities that are much higher than those of any of the currently reported sorbents.","Adsorption of divalent metal ions from aqueous solutions using graphene oxide Abs: The adsorptive properties of graphene oxide (GO) towards divalent metal ions (copper, zinc, cadmium and lead) were investigated. GO prepared through the oxidation of graphite using potassium dichromate was characterized by scanning electron microscopy (SEM), powder X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS) and infrared spectroscopy (FT-IR). The results of batch experiments and measurements by flame atomic absorption spectrometry (F-AAS) indicate that maximum adsorption can be achieved in broad pH ranges: 3-7 for Cu(II), 5-8 for Zn(II), 4-8 for Cd(II), 3-7 for Pb(II). The maximum adsorption capacities of Cu(II), Zn(II), Cd(II) and Pb(II) on GO at pH = 5 are 294, 345, 530, 1119 mg g(-1), respectively. The competitive adsorption experiments showed the affinity in the order of Pb(II) &gt; Cu(II) ? Cd(II) &gt; Zn(II). Adsorption isotherms and kinetic studies suggest that sorption of metal ions on GO nanosheets is monolayer coverage and adsorption is controlled by chemical adsorption involving the strong surface complexation of metal ions with the oxygen-containing groups on the surface of GO. Chemisorption was confirmed by XPS (binding energy and shape of O1s and C1s peaks) of GO with adsorbed metal ions. The adsorption experiments show that the dispersibility of GO in water changes remarkably after complexation of metal ions. After adsorption, the tendency to agglomerate and precipitate is observed. Excellent dispersibility of GO and strong tendency of GO-Me(II) to precipitate open the path to removal of heavy metals from water solution. Potential application of GO in analytical chemistry as a solid sorbent for preconcentration of trace elements and in heavy metal ion pollution cleanup results from its maximum adsorption capacities that are much higher than those of any of the currently reported sorbents."
1786256,Singh et al. 2013,Synergism of Pseudomonas aeruginosa and Fe0 for treatment of heavy metal contaminated effluents using small scale laboratory reactor,"In this study Pseudomonas aeruginosa a metal tolerant strain was not only applied for heavy metal removal but also to the solublization performance of the precipitated metal ions during effluent treatment. The synergistic effect of the isolate and Fe(0) enhanced the metal removal potential to 72.97% and 87.63% for Cr(VI) and cadmium, respectively. The decrease in cadmium ion removal to 43.65% (aeration+stirring reactors), 21.33% (aerated reactors), and 18.95% (without aerated+without stirring) with an increase in incubation period not only indicate the presence of soluble less toxic complexes, but also help in exploration of the balancing potential for valuable metal recovery. A relatively best fit and significant values of the correlation coefficient 0.912, 0.959, and 0.9314 for mixed effluent (Paint Industry effluent+CETP Wazirpur, effluent), CETP, Wazirpur, and control effluents, respectively, indicating first-order formulation and provide a reasonable description of COD kinetic data.","Synergism of Pseudomonas aeruginosa and Fe0 for treatment of heavy metal contaminated effluents using small scale laboratory reactor Abs: In this study Pseudomonas aeruginosa a metal tolerant strain was not only applied for heavy metal removal but also to the solublization performance of the precipitated metal ions during effluent treatment. The synergistic effect of the isolate and Fe(0) enhanced the metal removal potential to 72.97% and 87.63% for Cr(VI) and cadmium, respectively. The decrease in cadmium ion removal to 43.65% (aeration+stirring reactors), 21.33% (aerated reactors), and 18.95% (without aerated+without stirring) with an increase in incubation period not only indicate the presence of soluble less toxic complexes, but also help in exploration of the balancing potential for valuable metal recovery. A relatively best fit and significant values of the correlation coefficient 0.912, 0.959, and 0.9314 for mixed effluent (Paint Industry effluent+CETP Wazirpur, effluent), CETP, Wazirpur, and control effluents, respectively, indicating first-order formulation and provide a reasonable description of COD kinetic data."
1786255,Shen et al. 2013,Highly efficient detoxification of Cr(VI) by chitosan-Fe(III) complex: process and mechanism studies,"Metal-biopolymer complexes has recently gained significant attention as an effective adsorbent used for the removal of Cr(VI) from water. Unfortunately, despite increasing research efforts in the field of removal efficiency, whether this kind of complex can reduce Cr(VI) to less-toxic Cr(III) and what are the mechanisms of detoxification processes are still unknown. In this study, despite the highly adsorption efficiency (maximum adsorption capacity of 173.1 mg/g in 10 min), the significant improvement of Cr(VI) reduction by chitosan-Fe(III) complex compared with normal crosslinked chitoan has been demonstrated. In addition, the structure of chitosan-Fe(III) complex and its functional groups concerned with Cr(VI) detoxification have been characterized by the powerful spectroscopic techniques X-ray absorption fine structure (XAFS) and X-ray photoelectron spectroscopy (XPS). The XPS spectra indicated that the primary alcoholic function on C-6 served as an electron donor during Cr(VI) reduction and was oxidized to a carbonyl group. The X-ray adsorption near edge spectra (XANES) of the Cr(VI)-treated chitosan-Fe(III) complex revealed the similar geometrical arrangement of Cr species as that in Cr(III)-bound chitosan-Fe(III). Overall, a possible process and mechanism for highly efficient detoxification of Cr(VI) by chitosan-Fe(III) complex has been elucidate.","Highly efficient detoxification of Cr(VI) by chitosan-Fe(III) complex: process and mechanism studies Abs: Metal-biopolymer complexes has recently gained significant attention as an effective adsorbent used for the removal of Cr(VI) from water. Unfortunately, despite increasing research efforts in the field of removal efficiency, whether this kind of complex can reduce Cr(VI) to less-toxic Cr(III) and what are the mechanisms of detoxification processes are still unknown. In this study, despite the highly adsorption efficiency (maximum adsorption capacity of 173.1 mg/g in 10 min), the significant improvement of Cr(VI) reduction by chitosan-Fe(III) complex compared with normal crosslinked chitoan has been demonstrated. In addition, the structure of chitosan-Fe(III) complex and its functional groups concerned with Cr(VI) detoxification have been characterized by the powerful spectroscopic techniques X-ray absorption fine structure (XAFS) and X-ray photoelectron spectroscopy (XPS). The XPS spectra indicated that the primary alcoholic function on C-6 served as an electron donor during Cr(VI) reduction and was oxidized to a carbonyl group. The X-ray adsorption near edge spectra (XANES) of the Cr(VI)-treated chitosan-Fe(III) complex revealed the similar geometrical arrangement of Cr species as that in Cr(III)-bound chitosan-Fe(III). Overall, a possible process and mechanism for highly efficient detoxification of Cr(VI) by chitosan-Fe(III) complex has been elucidate."
1786254,Sharma and  Kothiyal ,"Use of activated dry flowers (ADF) of Alstonia Scholaris for chromium (Vl) removal: equilibrium, kinetics and thermodynamics studies","In this study, a natural adsorbent (activated dry flowers (ADF)) was prepared from plant-derived waste biomass by chemical activation and employed for chromium (VI) removal from aqueous medium using experimental batch technique. Experiments were carried out as function of adsorbent dosage, pH, and contact time. The maximum chromium (Vl) removal was observed at initial pH 3 (~94 % removal). The equilibrium data was fitted well to Langmuir isotherm. The adsorption capacity of ADF was found to be 4.40 (mg chromium (Vl)/g) which was comparable to the adsorption capacity of some other adsorbents documented. Among various kinetic models applied, pseudo second-order model was found to explain the kinetics of chromium (VI) adsorption most effectively (R (2) &gt;0.99). Thermodynamic parameters such as ?G, ?S, and ?H shows that adsorption process was spontaneous and endothermic at all the concentration ranges studied. Desorption of chromium (Vl) with 2 N NaOH was effective (~71 %) and, hence, there exists the possibility of recycling the ADF. The major advantages of using ADF as an adsorbent are due to its effectiveness in reducing the concentration of chromium (Vl) to very low levels. It requires little processing and is reversible as well as eco-friendly in contrast to traditional methods.","Use of activated dry flowers (ADF) of Alstonia Scholaris for chromium (Vl) removal: equilibrium, kinetics and thermodynamics studies Abs: In this study, a natural adsorbent (activated dry flowers (ADF)) was prepared from plant-derived waste biomass by chemical activation and employed for chromium (VI) removal from aqueous medium using experimental batch technique. Experiments were carried out as function of adsorbent dosage, pH, and contact time. The maximum chromium (Vl) removal was observed at initial pH 3 (~94 % removal). The equilibrium data was fitted well to Langmuir isotherm. The adsorption capacity of ADF was found to be 4.40 (mg chromium (Vl)/g) which was comparable to the adsorption capacity of some other adsorbents documented. Among various kinetic models applied, pseudo second-order model was found to explain the kinetics of chromium (VI) adsorption most effectively (R (2) &gt;0.99). Thermodynamic parameters such as ?G, ?S, and ?H shows that adsorption process was spontaneous and endothermic at all the concentration ranges studied. Desorption of chromium (Vl) with 2 N NaOH was effective (~71 %) and, hence, there exists the possibility of recycling the ADF. The major advantages of using ADF as an adsorbent are due to its effectiveness in reducing the concentration of chromium (Vl) to very low levels. It requires little processing and is reversible as well as eco-friendly in contrast to traditional methods."
1786253,Seidler et al. ,"Reply to: Pesch B, Weiss T, Pallapies D, Schlüter G, Brüning T. Letter to the editor. Re: Seidler A, Jähnichen S, Hegewald J, Fishta A, Krug O, Rüter L, Strik C, Hallier E, Straube S. Systematic review and quantification of respiratory cancer risk for occupational exposure to hexavalent chromium",,"Reply to: Pesch B, Weiss T, Pallapies D, Schlüter G, Brüning T. Letter to the editor. Re: Seidler A, Jähnichen S, Hegewald J, Fishta A, Krug O, Rüter L, Strik C, Hallier E, Straube S. Systematic review and quantification of respiratory cancer risk for occupational exposure to hexavalent chromium Abs: "
1786252,Scoccianti et al. ,Over-accumulation of putrescine induced by cyclohexylamine interferes with chromium accumulation and partially restores pollen tube growth in Actinidia deliciosa,"Both trivalent and hexavalent chromium, i.e., Cr(III) and Cr(VI), respectively, were previously demonstrated to affect in vitro germination and ultrastructure of kiwifruit (Actinidia deliciosa) pollen. In the present work, the response to chromium in germinating pollen was evaluated in terms of changes in the polyamine profile. Slight, though significant, increases in free spermidine and spermine occurred after exposure to Cr(III), while the levels remained almost unchanged after Cr(VI) treatment. The spermidine synthase inhibitor cyclohexylamine (CHA) caused a dramatic increase in free putrescine in both chromium-treated and untreated samples, while spermidine content was not affected. Interestingly, CHA positively affected the performance of chromium-treated pollen by partially, though significantly, restoring pollen tube growth. The major growth recovery was registered with 1 mM CHA in the presence of Cr(VI), concomitant with a considerable reduction in uptake of the metal. Conversely, endogenous calcium levels were more heavily affected in Cr(III)-treated pollen. The effect of CHA on production of reactive oxygen species also varied depending on the chromium species. The response of pollen to the CHA-induced putrescine excess was compared with that exerted by an exogenous supply of the same diamine. Results show that in Cr(III)-treated pollen, putrescine over-accumulation induced by CHA exerted similar effects as exogenous putrescine, while this was not true in the Cr(VI) treatment. It appears that the diamine was able to improve pollen tolerance to metal stress through different mechanisms, mostly depending upon the chromium species, namely via reduced metal uptake or by substituting for calcium.","Over-accumulation of putrescine induced by cyclohexylamine interferes with chromium accumulation and partially restores pollen tube growth in Actinidia deliciosa Abs: Both trivalent and hexavalent chromium, i.e., Cr(III) and Cr(VI), respectively, were previously demonstrated to affect in vitro germination and ultrastructure of kiwifruit (Actinidia deliciosa) pollen. In the present work, the response to chromium in germinating pollen was evaluated in terms of changes in the polyamine profile. Slight, though significant, increases in free spermidine and spermine occurred after exposure to Cr(III), while the levels remained almost unchanged after Cr(VI) treatment. The spermidine synthase inhibitor cyclohexylamine (CHA) caused a dramatic increase in free putrescine in both chromium-treated and untreated samples, while spermidine content was not affected. Interestingly, CHA positively affected the performance of chromium-treated pollen by partially, though significantly, restoring pollen tube growth. The major growth recovery was registered with 1 mM CHA in the presence of Cr(VI), concomitant with a considerable reduction in uptake of the metal. Conversely, endogenous calcium levels were more heavily affected in Cr(III)-treated pollen. The effect of CHA on production of reactive oxygen species also varied depending on the chromium species. The response of pollen to the CHA-induced putrescine excess was compared with that exerted by an exogenous supply of the same diamine. Results show that in Cr(III)-treated pollen, putrescine over-accumulation induced by CHA exerted similar effects as exogenous putrescine, while this was not true in the Cr(VI) treatment. It appears that the diamine was able to improve pollen tolerance to metal stress through different mechanisms, mostly depending upon the chromium species, namely via reduced metal uptake or by substituting for calcium."
1786251,Sarenqiqige et al. 2013,Solid-phase Spectrophotometry for On-site Analysis of Trace Elements in Natural Water,"A new, simple and sensitive solid-phase spectrometry (SPS) that is easily applicable to the on-site analysis of targeted chemical components in water at ?g dm(-3) or sub-?g dm(-3) levels is proposed in this study. The main features of the SPS are the simplicity of operation, high sensitivity and applicability to real samples without the need for any pretreatment procedures. A portable spectrophotometer, consisting of an LED light source, a grating and a CCD, was used for the solid-phase light measurements. The universal applicability of the proposed system to on-site analysis was evaluated by determining phosphate, chromium(VI) and iron(II) in natural water.","Solid-phase Spectrophotometry for On-site Analysis of Trace Elements in Natural Water Abs: A new, simple and sensitive solid-phase spectrometry (SPS) that is easily applicable to the on-site analysis of targeted chemical components in water at ?g dm(-3) or sub-?g dm(-3) levels is proposed in this study. The main features of the SPS are the simplicity of operation, high sensitivity and applicability to real samples without the need for any pretreatment procedures. A portable spectrophotometer, consisting of an LED light source, a grating and a CCD, was used for the solid-phase light measurements. The universal applicability of the proposed system to on-site analysis was evaluated by determining phosphate, chromium(VI) and iron(II) in natural water."
1786250,Saravanan et al. 2013,Sorption studies on heavy metal removal using chitin/bentonite biocomposite,"Contamination of water by toxic heavy metals due to urbanization is a world-wide environmental problem, which changes chemical and biological properties of both surface and ground water. The heavy metals render the water unsuitable for drinking and are also highly toxic to human beings. Removal of heavy metals is therefore essential. Thus, in my present work batch adsorption studies have been used to remove the Cr(VI) from aqueous solution using chitin composite. The data obtained from batch method at optimized conditions have been subjected to Freundlich and Langmuir isotherm studies. The data were suitable for both models indicating favorability.","Sorption studies on heavy metal removal using chitin/bentonite biocomposite Abs: Contamination of water by toxic heavy metals due to urbanization is a world-wide environmental problem, which changes chemical and biological properties of both surface and ground water. The heavy metals render the water unsuitable for drinking and are also highly toxic to human beings. Removal of heavy metals is therefore essential. Thus, in my present work batch adsorption studies have been used to remove the Cr(VI) from aqueous solution using chitin composite. The data obtained from batch method at optimized conditions have been subjected to Freundlich and Langmuir isotherm studies. The data were suitable for both models indicating favorability."
1786249,Konieczko et al. 2013,"[Chemical carcinogenic and mutagenic agents in the workplace, Poland, 2008-2010]","BACKGROUND: The aim of this paper is to present a concise but comprehensive information on the occurrence of carcinogenic or mutagenic agents in Polish enterprises and the number of workers exposed to those agents reported to the central register by employers. Objectives and responsibilities of the register, as well as the range and methods of data gathering are discussed. MATERIAL AND METHODS: Data concerning carcinogenic or mutagenic chemical substances and technological processes reported to central register in 2008-2010 were analyzed. RESULTS: In 2008-2010 more than 300 carcinogenic or mutagenic chemical substances were reported to the register. Approximately 2500 plants reported above 150 000 per-person-exposures annually. Among all technological processes regarded as occupational carcinogens, hardwood dusts exposure (about 660 companies; 11 000-13 000 exposed workers each year) and exposure to polycyclic aromatic hydrocarbons (PAHs) present in coal products (117-125 plantsl 3000 exposed per year) were reported. CONCLUSIONS: The most widespread carcinogenic/mutagenic substances were: benzene, chromium(VI) compounds: potassium dichromate and chromate, chromium(VI) trioxide and other chromium compounds, ethylene oxide, asbestos, benzo[a]pyrene and gasoline. The highest number of men was exposed to particular PAHs and benzene, and the majority of women was exposed to benzene, potassium dichromate and chromate, acrylamide, ethylene oxide and gasoline. The lack of clear-cut definition of occupational exposure to carcinogen creates a problem faced by employers in defining the accurate number of exposed workers.","[Chemical carcinogenic and mutagenic agents in the workplace, Poland, 2008-2010] Abs: BACKGROUND: The aim of this paper is to present a concise but comprehensive information on the occurrence of carcinogenic or mutagenic agents in Polish enterprises and the number of workers exposed to those agents reported to the central register by employers. Objectives and responsibilities of the register, as well as the range and methods of data gathering are discussed. MATERIAL AND METHODS: Data concerning carcinogenic or mutagenic chemical substances and technological processes reported to central register in 2008-2010 were analyzed. RESULTS: In 2008-2010 more than 300 carcinogenic or mutagenic chemical substances were reported to the register. Approximately 2500 plants reported above 150 000 per-person-exposures annually. Among all technological processes regarded as occupational carcinogens, hardwood dusts exposure (about 660 companies; 11 000-13 000 exposed workers each year) and exposure to polycyclic aromatic hydrocarbons (PAHs) present in coal products (117-125 plantsl 3000 exposed per year) were reported. CONCLUSIONS: The most widespread carcinogenic/mutagenic substances were: benzene, chromium(VI) compounds: potassium dichromate and chromate, chromium(VI) trioxide and other chromium compounds, ethylene oxide, asbestos, benzo[a]pyrene and gasoline. The highest number of men was exposed to particular PAHs and benzene, and the majority of women was exposed to benzene, potassium dichromate and chromate, acrylamide, ethylene oxide and gasoline. The lack of clear-cut definition of occupational exposure to carcinogen creates a problem faced by employers in defining the accurate number of exposed workers."
1786248,Jin et al. 2013,[Cytotoxicity and genome-wide microarray analysis of intestinal smooth muscle cells in response to hexavalent chromium induction],"Chronic ingestion of high concentrations of hexavalent chromium [Cr(VI)] in drinking water induces intestinal tumors in mice; however, information on its toxicity on intestinal smooth muscle cells is limited. The present study aimed to assess the in vitro and in vivo toxicological effects of Cr(VI) on intestinal smooth muscle cells. Human intestinal smooth muscle cells (HISM cells) were cultured with different concentrations of Cr(VI) to evaluate effects on cell proliferation ability, oxidative stress levels, and antioxidant system. Furthermore, tissue sections in Cr(VI) exposed rabbits were analyzed to evaluate toxicity on intestinal muscle cells in vivo. Gene chips were utilized to assess differential gene expression profiles at the genome-wide level in 1 mumol/L Cr(VI) treated cells. Intestinal tissue biopsy results showed that Cr(VI) increased the incidences of diffuse epithelial hyperplasia in intestinal jejunum but caused no obvious damage to the structure of the muscularis. Cell proliferation analysis revealed that high concentrations (>/=64 mumol/L) but not low concentrations of Cr(VI) (</=16 mumol/L) significantly inhibited the growth of HISM cells. For oxidative stress levels, the expression of reactive oxygen species (ROS) and nitric oxide (NO) was elevated at high concentrations (>/=64 mumol/L) but not at low concentrations of Cr(VI) (</=16 mumol/L). In addition, dose-dependent increases in the activity of oxidized glutathione (GSSH)/total-glutathione (T-GSH) were also observed. Gene chip screened 491 differentially expressed genes including genes associated with cell apoptosis, oxidations, and cytoskeletons. Some of these differentially expressed genes may be unique to smooth muscle cells in response to Cr(VI) induction.","[Cytotoxicity and genome-wide microarray analysis of intestinal smooth muscle cells in response to hexavalent chromium induction] Abs: Chronic ingestion of high concentrations of hexavalent chromium [Cr(VI)] in drinking water induces intestinal tumors in mice; however, information on its toxicity on intestinal smooth muscle cells is limited. The present study aimed to assess the in vitro and in vivo toxicological effects of Cr(VI) on intestinal smooth muscle cells. Human intestinal smooth muscle cells (HISM cells) were cultured with different concentrations of Cr(VI) to evaluate effects on cell proliferation ability, oxidative stress levels, and antioxidant system. Furthermore, tissue sections in Cr(VI) exposed rabbits were analyzed to evaluate toxicity on intestinal muscle cells in vivo. Gene chips were utilized to assess differential gene expression profiles at the genome-wide level in 1 mumol/L Cr(VI) treated cells. Intestinal tissue biopsy results showed that Cr(VI) increased the incidences of diffuse epithelial hyperplasia in intestinal jejunum but caused no obvious damage to the structure of the muscularis. Cell proliferation analysis revealed that high concentrations (>/=64 mumol/L) but not low concentrations of Cr(VI) (</=16 mumol/L) significantly inhibited the growth of HISM cells. For oxidative stress levels, the expression of reactive oxygen species (ROS) and nitric oxide (NO) was elevated at high concentrations (>/=64 mumol/L) but not at low concentrations of Cr(VI) (</=16 mumol/L). In addition, dose-dependent increases in the activity of oxidized glutathione (GSSH)/total-glutathione (T-GSH) were also observed. Gene chip screened 491 differentially expressed genes including genes associated with cell apoptosis, oxidations, and cytoskeletons. Some of these differentially expressed genes may be unique to smooth muscle cells in response to Cr(VI) induction."
1786247,Robins et al. 2013,Escherichia coli NemA is an efficient chromate reductase that can be biologically immobilized to provide a cell free system for remediation of hexavalent chromium,"Hexavalent chromium is a serious and widespread environmental pollutant. Although many bacteria have been identified that can transform highly water-soluble and toxic Cr(VI) to insoluble and relatively non-toxic Cr(III), bacterial bioremediation of Cr(VI) pollution is limited by a number of issues, in particular chromium toxicity to the remediating cells. To address this we sought to develop an immobilized enzymatic system for Cr(VI) remediation. To identify novel Cr(VI) reductase enzymes we first screened cell extracts from an Escherichia coli library of soluble oxidoreductases derived from a range of bacteria, but found that a number of these enzymes can reduce Cr(VI) indirectly, via redox intermediates present in the crude extracts. Instead, activity assays for 15 candidate enzymes purified as His6-tagged proteins identified E. coli NemA as a highly efficient Cr(VI) reductase (k(cat)/K(M)=?1.1×10(5) M(-1) s(-1) with NADH as cofactor). Fusion of nemA to the polyhydroxyalkanoate synthase gene phaC from Ralstonia eutropha enabled high-level biosynthesis of functionalized polyhydroxyalkanoate granules displaying stable and active NemA on their surface. When these granules were combined with either Bacillus subtilis glucose dehydrogenase or Candida boidinii formate dehydrogenase as a cofactor regenerating partner, high levels of chromate transformation were observed with only low initial concentrations of expensive NADH cofactor being required, the overall reaction being powered by consumption of the cheap sacrificial substrates glucose or formic acid, respectively. This system therefore offers promise as an economic solution for ex situ Cr(VI) remediation.","Escherichia coli NemA is an efficient chromate reductase that can be biologically immobilized to provide a cell free system for remediation of hexavalent chromium Abs: Hexavalent chromium is a serious and widespread environmental pollutant. Although many bacteria have been identified that can transform highly water-soluble and toxic Cr(VI) to insoluble and relatively non-toxic Cr(III), bacterial bioremediation of Cr(VI) pollution is limited by a number of issues, in particular chromium toxicity to the remediating cells. To address this we sought to develop an immobilized enzymatic system for Cr(VI) remediation. To identify novel Cr(VI) reductase enzymes we first screened cell extracts from an Escherichia coli library of soluble oxidoreductases derived from a range of bacteria, but found that a number of these enzymes can reduce Cr(VI) indirectly, via redox intermediates present in the crude extracts. Instead, activity assays for 15 candidate enzymes purified as His6-tagged proteins identified E. coli NemA as a highly efficient Cr(VI) reductase (k(cat)/K(M)=?1.1×10(5) M(-1) s(-1) with NADH as cofactor). Fusion of nemA to the polyhydroxyalkanoate synthase gene phaC from Ralstonia eutropha enabled high-level biosynthesis of functionalized polyhydroxyalkanoate granules displaying stable and active NemA on their surface. When these granules were combined with either Bacillus subtilis glucose dehydrogenase or Candida boidinii formate dehydrogenase as a cofactor regenerating partner, high levels of chromate transformation were observed with only low initial concentrations of expensive NADH cofactor being required, the overall reaction being powered by consumption of the cheap sacrificial substrates glucose or formic acid, respectively. This system therefore offers promise as an economic solution for ex situ Cr(VI) remediation."
1786246,Rajiv Gandhi and  Meenakshi 2013,Preparation of amino terminated polyamidoamine functionalized chitosan beads and its Cr(VI) uptake studies,"Chitosan beads, functionalized by amino terminated hyperbranched dendritic polyamidoamine (up to 3rd generation) were prepared by Michael addition of methyl acrylate to amino groups on the chitosan surface and amidation of terminal ester groups by ethylene diamine. All the three generation chitosan beads were used for chromium removal along with raw chitosan beads. However, the 3rd generation polyamidoamine chitosan beads (3ACB) have been protonated using HCl (3ACBP)/loaded with zirconium using ZrOCl(2)·8H(2)O (3ACBZr) to enhance the sorption capacity towards Cr(VI). The zirconium loaded chitosan beads showed higher Cr(VI) sorption than the other modified chitosan beads. The zirconium loaded chitosan beads were characterized using SEM, EDAX, FT-IR, XRD, DSC and TGA. The system variables studied include agitation time, initial concentration of sorbate, pH, co-ions in the medium and temperature on the sorption of chromium. The chromium uptake onto 3ACBZr obeys the Freundlich isotherm. Thermodynamic studies revealed that the nature of chromium sorption is spontaneous and endothermic. The mechanism of chromium sorption onto the sorbent was established.","Preparation of amino terminated polyamidoamine functionalized chitosan beads and its Cr(VI) uptake studies Abs: Chitosan beads, functionalized by amino terminated hyperbranched dendritic polyamidoamine (up to 3rd generation) were prepared by Michael addition of methyl acrylate to amino groups on the chitosan surface and amidation of terminal ester groups by ethylene diamine. All the three generation chitosan beads were used for chromium removal along with raw chitosan beads. However, the 3rd generation polyamidoamine chitosan beads (3ACB) have been protonated using HCl (3ACBP)/loaded with zirconium using ZrOCl(2)·8H(2)O (3ACBZr) to enhance the sorption capacity towards Cr(VI). The zirconium loaded chitosan beads showed higher Cr(VI) sorption than the other modified chitosan beads. The zirconium loaded chitosan beads were characterized using SEM, EDAX, FT-IR, XRD, DSC and TGA. The system variables studied include agitation time, initial concentration of sorbate, pH, co-ions in the medium and temperature on the sorption of chromium. The chromium uptake onto 3ACBZr obeys the Freundlich isotherm. Thermodynamic studies revealed that the nature of chromium sorption is spontaneous and endothermic. The mechanism of chromium sorption onto the sorbent was established."
1786245,Qiu et al. 2013,Alleviation of chromium toxicity in rice seedlings by applying exogenous glutathione,"The effect of exogenous reduced glutathione (GSH) on alleviation of hexavalent chromium (Cr(6+)) toxicity to rice seedlings and its physiological mechanisms were comprehensively investigated in a series of experiments. Our results showed that growth and nutrient uptake of rice seedlings were dramatically reduced under 100 ?M Cr(6+) stress, and the reduction was significantly alleviated by exogenous GSH. Cr(6+) stress also reduced cell viability in root tips and damaged ultrastructure of both chloroplasts and root cells, while the addition of GSH alleviates those negative effects. Cr-induced toxicity and GSH-caused Cr alleviation differed significantly between Cr-tolerant Line 117 (L117) and Cr-sensitive Line 41 (L41). Under Cr(6+) stress, cystine content was increased and GSH content was decreased in rice plants, exogenous GSH, however, mitigated the Cr-toxicity by reversing the Cr-induced changes of the two compounds. The types of Cr-induced secretion of organic acids varied between the genotypes, where reduction in the contents of acetic and lactic acids and tartaric and malic acids were observed in L117 and L41, respectively. The addition of GSH alleviated the reduction of secretion of these organic acids. Exogenous GSH also altered the forms of Cr ions in the rhizosphere and the fraction of distribution at subcellular level in both shoots and roots. It may be concluded that the alleviation of Cr(6+) toxicity by exogenous GSH is directly attributed to its regulation on forms of Cr ions in rhizosphere and their distribution at subcellular levels.","Alleviation of chromium toxicity in rice seedlings by applying exogenous glutathione Abs: The effect of exogenous reduced glutathione (GSH) on alleviation of hexavalent chromium (Cr(6+)) toxicity to rice seedlings and its physiological mechanisms were comprehensively investigated in a series of experiments. Our results showed that growth and nutrient uptake of rice seedlings were dramatically reduced under 100 ?M Cr(6+) stress, and the reduction was significantly alleviated by exogenous GSH. Cr(6+) stress also reduced cell viability in root tips and damaged ultrastructure of both chloroplasts and root cells, while the addition of GSH alleviates those negative effects. Cr-induced toxicity and GSH-caused Cr alleviation differed significantly between Cr-tolerant Line 117 (L117) and Cr-sensitive Line 41 (L41). Under Cr(6+) stress, cystine content was increased and GSH content was decreased in rice plants, exogenous GSH, however, mitigated the Cr-toxicity by reversing the Cr-induced changes of the two compounds. The types of Cr-induced secretion of organic acids varied between the genotypes, where reduction in the contents of acetic and lactic acids and tartaric and malic acids were observed in L117 and L41, respectively. The addition of GSH alleviated the reduction of secretion of these organic acids. Exogenous GSH also altered the forms of Cr ions in the rhizosphere and the fraction of distribution at subcellular level in both shoots and roots. It may be concluded that the alleviation of Cr(6+) toxicity by exogenous GSH is directly attributed to its regulation on forms of Cr ions in rhizosphere and their distribution at subcellular levels."
1786244,Pesch et al. ,"Re: Seidler A, Jänichen S, Hegewald J et al. Systematic review and quantification of respiratory cancer risk for occupational exposure to hexavalent chromium",,"Re: Seidler A, Jänichen S, Hegewald J et al. Systematic review and quantification of respiratory cancer risk for occupational exposure to hexavalent chromium Abs: "
1786243,Pereira et al. ,Bioadsorption and bioaccumulation of chromium trivalent in Cr(III)-tolerant microalgae: A mechanisms for chromium resistance,"Anthropogenic activity constantly releases heavy metals into the environment. The heavy metal chromium has a wide industrial use and exists in two stable oxidation states: trivalent and hexavalent. While hexavalent chromium uptake in plant cells has been reported that an active process by carrying essential anions, the cation Cr(III) appears to be taken up inactively. Dictyosphaerium chlorelloides (Dc1M), an unicellular green alga is a well-studied cell biological model organism. The present study was carried out to investigate the toxic effect of chromium exposures on wild-type Cr(III)-sensitive (Dc1M(wt)) and Cr(III)-tolerant (Dc1M(Cr(III)R30)) strains of these green algae, and to determine the potential mechanism of chromium resistance. Using cell growth as endpoint to determine Cr(III)-sensitivity, the IC50(72) values obtained show significant differences of sensitivity between wild type and Cr(III)-tolerant cells. Scanning electron microscopy (SEM) showed significant morphological differences between both strains, such as decrease in cell size or reducing the coefficient of form; and transmission electron microscopy (TEM) revealed ultrastructural changes such as increased vacuolization and cell wall thickening in the Cr(III)-tolerant strain with respect to the wild-type strain. Energy dispersive X-ray analysis (SEM/XEDS) revealed that Cr(III)-tolerant D. chlorelloides cells are able to accumulate considerable amounts of chromium distributed in cell wall (bioadsorption) as well as in cytoplasm, vacuoles, and chloroplast (bio-accumulation). Morphological changes of Cr(III)-tolerant D. chlorelloides cells and the presence of these electron-dense bodies in their cell structures can be understood as a Cr(III) detoxification mechanism.","Bioadsorption and bioaccumulation of chromium trivalent in Cr(III)-tolerant microalgae: A mechanisms for chromium resistance Abs: Anthropogenic activity constantly releases heavy metals into the environment. The heavy metal chromium has a wide industrial use and exists in two stable oxidation states: trivalent and hexavalent. While hexavalent chromium uptake in plant cells has been reported that an active process by carrying essential anions, the cation Cr(III) appears to be taken up inactively. Dictyosphaerium chlorelloides (Dc1M), an unicellular green alga is a well-studied cell biological model organism. The present study was carried out to investigate the toxic effect of chromium exposures on wild-type Cr(III)-sensitive (Dc1M(wt)) and Cr(III)-tolerant (Dc1M(Cr(III)R30)) strains of these green algae, and to determine the potential mechanism of chromium resistance. Using cell growth as endpoint to determine Cr(III)-sensitivity, the IC50(72) values obtained show significant differences of sensitivity between wild type and Cr(III)-tolerant cells. Scanning electron microscopy (SEM) showed significant morphological differences between both strains, such as decrease in cell size or reducing the coefficient of form; and transmission electron microscopy (TEM) revealed ultrastructural changes such as increased vacuolization and cell wall thickening in the Cr(III)-tolerant strain with respect to the wild-type strain. Energy dispersive X-ray analysis (SEM/XEDS) revealed that Cr(III)-tolerant D. chlorelloides cells are able to accumulate considerable amounts of chromium distributed in cell wall (bioadsorption) as well as in cytoplasm, vacuoles, and chloroplast (bio-accumulation). Morphological changes of Cr(III)-tolerant D. chlorelloides cells and the presence of these electron-dense bodies in their cell structures can be understood as a Cr(III) detoxification mechanism."
1786242,Pabuwal et al. 2013,Transcriptomic analysis of cultured whale skin cells exposed to hexavalent chromium [Cr(VI)],"Hexavalent chromium Cr(VI) is known to produce cytotoxic effects in humans and is a highly toxic environmental contaminant. Interestingly, it has been shown that free ranging sperm whales (Phyester macrocephalus) may have exceedingly high levels of Cr in their skin. Also, it has been demonstrated that skin cells from whales appear more resistant to both cytotoxicity and clastogenicity upon Cr exposure compared to human cells. However, the molecular genetic mechanisms employed in whale skin cells that might lead to Cr tolerance are unknown. In an effort to understand the underlying mechanisms of Cr(VI) tolerance and to illuminate global gene expression patterns modulated by Cr, we exposed whale skin cells in culture to varying levels of Cr(VI) (i.e., 0.0, 0.5, 1.0 and 5.0 ?g/cm²) followed by short read (100 bp) next generation RNA sequencing (RNA-seq). RNA-seq reads from all exposures (?280 million reads) were pooled to generate a de novo reference transcriptome assembly. The resulting whale reference assembly had 11K contigs and an N50 of 2954 bp. Using the reads from each dose (0.0, 0.5, 1.0 and 5.0 ?g/cm²) we performed RNA-seq based gene expression analysis that identified 35 up-regulated genes and 19 down-regulated genes. The experimental results suggest that low dose exposure to Cr (1.0 ?g/cm²) serves to induce up-regulation of oxidative stress response genes, DNA repair genes and cell cycle regulator genes. However, at higher doses (5.0 ?g/cm²) the DNA repair genes appeared down-regulated while other genes that were induced suggest the initiation of cytotoxicity. The set of genes identified that show regulatory modulation at different Cr doses provide specific candidates for further studies aimed at determination of how whales exhibit resistance to Cr toxicity and what role(s) reactive oxygen species (ROS) may play in this process.","Transcriptomic analysis of cultured whale skin cells exposed to hexavalent chromium [Cr(VI)] Abs: Hexavalent chromium Cr(VI) is known to produce cytotoxic effects in humans and is a highly toxic environmental contaminant. Interestingly, it has been shown that free ranging sperm whales (Phyester macrocephalus) may have exceedingly high levels of Cr in their skin. Also, it has been demonstrated that skin cells from whales appear more resistant to both cytotoxicity and clastogenicity upon Cr exposure compared to human cells. However, the molecular genetic mechanisms employed in whale skin cells that might lead to Cr tolerance are unknown. In an effort to understand the underlying mechanisms of Cr(VI) tolerance and to illuminate global gene expression patterns modulated by Cr, we exposed whale skin cells in culture to varying levels of Cr(VI) (i.e., 0.0, 0.5, 1.0 and 5.0 ?g/cm²) followed by short read (100 bp) next generation RNA sequencing (RNA-seq). RNA-seq reads from all exposures (?280 million reads) were pooled to generate a de novo reference transcriptome assembly. The resulting whale reference assembly had 11K contigs and an N50 of 2954 bp. Using the reads from each dose (0.0, 0.5, 1.0 and 5.0 ?g/cm²) we performed RNA-seq based gene expression analysis that identified 35 up-regulated genes and 19 down-regulated genes. The experimental results suggest that low dose exposure to Cr (1.0 ?g/cm²) serves to induce up-regulation of oxidative stress response genes, DNA repair genes and cell cycle regulator genes. However, at higher doses (5.0 ?g/cm²) the DNA repair genes appeared down-regulated while other genes that were induced suggest the initiation of cytotoxicity. The set of genes identified that show regulatory modulation at different Cr doses provide specific candidates for further studies aimed at determination of how whales exhibit resistance to Cr toxicity and what role(s) reactive oxygen species (ROS) may play in this process."
1786241,Oves et al. 2013,Antibacterial and cytotoxic efficacy of extracellular silver nanoparticles biofabricated from chromium reducing novel OS4 strain of Stenotrophomonas maltophilia,"Biofabricated metal nanoparticles are generally biocompatible, inexpensive, and ecofriendly, therefore, are used preferably in industries, medical and material science research. Considering the importance of biofabricated materials, we isolated, characterized and identified a novel bacterial strain OS4 of Stenotrophomonas maltophilia (GenBank: JN247637.1). At neutral pH, this Gram negative bacterial strain significantly reduced hexavalent chromium, an important heavy metal contaminant found in the tannery effluents and minings. Subsequently, even at room temperature the supernatant of log phase grown culture of strain OS4 also reduced silver nitrate (AgNO3) to generate nanoparticles (AgNPs). These AgNPs were further characterized by UV-visible, Nanophox particle size analyzer, XRD, SEM and FTIR. As evident from the FTIR data, plausibly the protein components of supernatant caused the reduction of AgNO3. The cuboid and homogenous AgNPs showed a characteristic UV-visible peak at 428 nm with average size of ~93 nm. The XRD spectra exhibited the characteristic Bragg peaks of 111, 200, 220 and 311 facets of the face centred cubic symmetry of nanoparticles suggesting that these nanoparticles were crystalline in nature. From the nanoparticle release kinetics data, the rapid release of AgNPs was correlated with the particle size and increasing surface area of the nanoparticles. A highly significant antimicrobial activity against medically important bacteria by the biofabricated AgNPs was also revealed as decline in growth of Staphylococcus aureus (91%), Escherichia coli (69%) and Serratia marcescens (66%) substantially. Additionally, different cytotoxic assays showed no toxicity of AgNPs to liver function, RBCs, splenocytes and HeLa cells, hence these particles were safe to use. Therefore, this novel bacterial strain OS4 is likely to provide broad spectrum benefits for curing chromium polluted sites, for biofabrication of AgNPs and ultimately in the nanoparticle based drug formulation for the treatment of infectious diseases.","Antibacterial and cytotoxic efficacy of extracellular silver nanoparticles biofabricated from chromium reducing novel OS4 strain of Stenotrophomonas maltophilia Abs: Biofabricated metal nanoparticles are generally biocompatible, inexpensive, and ecofriendly, therefore, are used preferably in industries, medical and material science research. Considering the importance of biofabricated materials, we isolated, characterized and identified a novel bacterial strain OS4 of Stenotrophomonas maltophilia (GenBank: JN247637.1). At neutral pH, this Gram negative bacterial strain significantly reduced hexavalent chromium, an important heavy metal contaminant found in the tannery effluents and minings. Subsequently, even at room temperature the supernatant of log phase grown culture of strain OS4 also reduced silver nitrate (AgNO3) to generate nanoparticles (AgNPs). These AgNPs were further characterized by UV-visible, Nanophox particle size analyzer, XRD, SEM and FTIR. As evident from the FTIR data, plausibly the protein components of supernatant caused the reduction of AgNO3. The cuboid and homogenous AgNPs showed a characteristic UV-visible peak at 428 nm with average size of ~93 nm. The XRD spectra exhibited the characteristic Bragg peaks of 111, 200, 220 and 311 facets of the face centred cubic symmetry of nanoparticles suggesting that these nanoparticles were crystalline in nature. From the nanoparticle release kinetics data, the rapid release of AgNPs was correlated with the particle size and increasing surface area of the nanoparticles. A highly significant antimicrobial activity against medically important bacteria by the biofabricated AgNPs was also revealed as decline in growth of Staphylococcus aureus (91%), Escherichia coli (69%) and Serratia marcescens (66%) substantially. Additionally, different cytotoxic assays showed no toxicity of AgNPs to liver function, RBCs, splenocytes and HeLa cells, hence these particles were safe to use. Therefore, this novel bacterial strain OS4 is likely to provide broad spectrum benefits for curing chromium polluted sites, for biofabrication of AgNPs and ultimately in the nanoparticle based drug formulation for the treatment of infectious diseases."
1786240,Ostash et al. ,"Cultivable actinomycetes from rhizosphere of birch (Betula pendula) growing on a coal mine dump in Silets, Ukraine","Five actinomycete strains were isolated from the rhizosphere of birch, one of a few native tree forms capable of thriving on the upper level of a coal mine dump near the village of Silets (Lvivska region, Ukraine). No such strains were isolated from surrounding gangue, or from nearby grass Calamagrostis epigeios. Using 16S rDNA sequencing and analysis of cell wall aminoacids, four of these strains were shown to belong to genus Streptomyces and one to be Amycolatopsis. The isolates were able to produce siderophores and antibacterial compounds. In comparison to the reference strain Streptomyces coelicolor M145, certain rhizospheric isolates displayed somewhat increased survival in the presence of copper, iron(III), or chromium(VI) salts. The Amycolatopsis isolate was also shown to accumulate significant quantities of heavy metals from waste extracts. Possible roles of the described strains in coal mine dump ecology are discussed.","Cultivable actinomycetes from rhizosphere of birch (Betula pendula) growing on a coal mine dump in Silets, Ukraine Abs: Five actinomycete strains were isolated from the rhizosphere of birch, one of a few native tree forms capable of thriving on the upper level of a coal mine dump near the village of Silets (Lvivska region, Ukraine). No such strains were isolated from surrounding gangue, or from nearby grass Calamagrostis epigeios. Using 16S rDNA sequencing and analysis of cell wall aminoacids, four of these strains were shown to belong to genus Streptomyces and one to be Amycolatopsis. The isolates were able to produce siderophores and antibacterial compounds. In comparison to the reference strain Streptomyces coelicolor M145, certain rhizospheric isolates displayed somewhat increased survival in the presence of copper, iron(III), or chromium(VI) salts. The Amycolatopsis isolate was also shown to accumulate significant quantities of heavy metals from waste extracts. Possible roles of the described strains in coal mine dump ecology are discussed."
1786239,O'Brien et al. 2013,Assessment of K-Ras mutant frequency and micronucleus incidence in the mouse duodenum following 90-days of exposure to Cr(VI) in drinking water,"Chronic exposure to high concentrations of hexavalent chromium [Cr(VI)] as sodium dichromate dihydrate (SDD) in drinking water induces duodenal tumors in mice, but the mode of action (MOA) for these tumors has been a subject of scientific debate. To evaluate the tumor-site-specific genotoxicity and cytotoxicity of SDD in the mouse small intestine, tissue pathology and cytogenetic damage were evaluated in duodenal crypt and villus enterocytes from B6C3F1 mice exposed to 0.3-520mg/L SDD in drinking water for 7 and 90 days. Allele-competitive blocker PCR (ACB-PCR) was used to investigate the induction of a sensitive, tumor-relevant mutation, specifically in vivo K-Ras codon 12 GAT mutation, in scraped duodenal epithelium following 90 days of drinking water exposure. Cytotoxicity was evident in the villus as disruption of cellular arrangement, desquamation, nuclear atypia and blunting. Following 90 days of treatment, aberrant nuclei, occurring primarily at villi tips, were significantly increased at ?60mg/L SDD. However, in the crypt compartment, there were no dose-related effects on mitotic and apoptotic indices or the formation of aberrant nuclei indicating that Cr(VI)-induced cytotoxicity was limited to the villi. Cr(VI) caused a dose-dependent proliferative response in the duodenal crypt as evidenced by an increase in crypt area and increased number of crypt enterocytes. Spontaneous K-Ras codon 12 GAT mutations in untreated mice were higher than expected, in the range of 10(-2) to 10(-3); however no treatment-related trend in the K-Ras codon 12 GAT mutation was observed. The high spontaneous background K-Ras mutant frequency and Cr(VI) dose-related increases in crypt enterocyte proliferation, without dose-related increase in K-Ras mutant frequency, micronuclei formation, or change in mitotic or apoptotic indices, are consistent with a lack of genotoxicity in the crypt compartment, and a MOA involving accumulation of mutations late in carcinogenesis as a consequence of sustained regenerative proliferation.","Assessment of K-Ras mutant frequency and micronucleus incidence in the mouse duodenum following 90-days of exposure to Cr(VI) in drinking water Abs: Chronic exposure to high concentrations of hexavalent chromium [Cr(VI)] as sodium dichromate dihydrate (SDD) in drinking water induces duodenal tumors in mice, but the mode of action (MOA) for these tumors has been a subject of scientific debate. To evaluate the tumor-site-specific genotoxicity and cytotoxicity of SDD in the mouse small intestine, tissue pathology and cytogenetic damage were evaluated in duodenal crypt and villus enterocytes from B6C3F1 mice exposed to 0.3-520mg/L SDD in drinking water for 7 and 90 days. Allele-competitive blocker PCR (ACB-PCR) was used to investigate the induction of a sensitive, tumor-relevant mutation, specifically in vivo K-Ras codon 12 GAT mutation, in scraped duodenal epithelium following 90 days of drinking water exposure. Cytotoxicity was evident in the villus as disruption of cellular arrangement, desquamation, nuclear atypia and blunting. Following 90 days of treatment, aberrant nuclei, occurring primarily at villi tips, were significantly increased at ?60mg/L SDD. However, in the crypt compartment, there were no dose-related effects on mitotic and apoptotic indices or the formation of aberrant nuclei indicating that Cr(VI)-induced cytotoxicity was limited to the villi. Cr(VI) caused a dose-dependent proliferative response in the duodenal crypt as evidenced by an increase in crypt area and increased number of crypt enterocytes. Spontaneous K-Ras codon 12 GAT mutations in untreated mice were higher than expected, in the range of 10(-2) to 10(-3); however no treatment-related trend in the K-Ras codon 12 GAT mutation was observed. The high spontaneous background K-Ras mutant frequency and Cr(VI) dose-related increases in crypt enterocyte proliferation, without dose-related increase in K-Ras mutant frequency, micronuclei formation, or change in mitotic or apoptotic indices, are consistent with a lack of genotoxicity in the crypt compartment, and a MOA involving accumulation of mutations late in carcinogenesis as a consequence of sustained regenerative proliferation."
1786238,Nethaji et al. 2013,Preparation and characterization of corn cob activated carbon coated with nano-sized magnetite particles for the removal of Cr(VI),"Activated carbon prepared from corn cob biomass, magnetized by magnetite nanoparticles (MCCAC) was used for the adsorption of hexavalent chromium from aqueous solution. The adsorbent was characterized by SEM, TEM, XRD, VSM, surface functionality and zero-point charge. The iron oxide nanoparticles were of 50 nm sizes and the saturation magnetization value for the adsorbent is 48.43 emu/g. Adsorption was maximum at pH 2. Isotherm data were modeled using Langmuir, Freundlich and Temkin isotherm. The prepared MCCAC had a heterogeneous surface. The maximum monolayer adsorption capacity was 57.37 mg/g. Kinetic studies were carried out and the data fitted the pseudo second-order equation. The mechanism of the adsorption process was studied by incorporating the kinetic data with intraparticle diffusion model, Bangham equation and Boyd plot. The adsorption was by chemisorption and the external mass transfer was the rate-determining step. A micro column was designed and the basic column parameters were estimated.","Preparation and characterization of corn cob activated carbon coated with nano-sized magnetite particles for the removal of Cr(VI) Abs: Activated carbon prepared from corn cob biomass, magnetized by magnetite nanoparticles (MCCAC) was used for the adsorption of hexavalent chromium from aqueous solution. The adsorbent was characterized by SEM, TEM, XRD, VSM, surface functionality and zero-point charge. The iron oxide nanoparticles were of 50 nm sizes and the saturation magnetization value for the adsorbent is 48.43 emu/g. Adsorption was maximum at pH 2. Isotherm data were modeled using Langmuir, Freundlich and Temkin isotherm. The prepared MCCAC had a heterogeneous surface. The maximum monolayer adsorption capacity was 57.37 mg/g. Kinetic studies were carried out and the data fitted the pseudo second-order equation. The mechanism of the adsorption process was studied by incorporating the kinetic data with intraparticle diffusion model, Bangham equation and Boyd plot. The adsorption was by chemisorption and the external mass transfer was the rate-determining step. A micro column was designed and the basic column parameters were estimated."
1786237,Narayani and  Vidya Shetty ,Reduction of hexavalent chromium by a novel Ochrobactrum sp. - microbial characteristics and reduction kinetics,"A Gram negative hexavalent chromium (Cr(VI)) reducing bacteria, Ochrobactrum sp. Cr-B4 (genbank accession number: JF824998) was isolated from the aerator water of an activated sludge process of a wastewater treatment facility of a dye and pigment based specialty chemical industry. It showed a resistance for 1000?mg?L(-1) Cr(VI). It exhibited resistance against other heavy metal ions like Ni(2+) (900?mg?L(-1) ), Cu(2+) (500?mg?L(-1) ), Pb(2+) (800?mg?L(-1) ), and Cd(2+) (250?mg?L(-1) ), Zn(2+) (700?mg?L(-1) ), Fe(3+) (800?mg?L(-1) ), and against selected antibiotics. Cr-B4 could efficiently reduce 200?mg?L(-1) Cr(VI) completely in nutrient and LB media and could convert Cr(VI) to Cr(III) efficiently. Cr(VI) reduction in nutrient media followed allosteric enzyme kinetics with Km values of 59.39?mg?L(-1) and Vmax values of 47.03?mg?L(-1) ?h(-1) . The reduction in LB media followed Michaelis-Menten kinetics with Km values of 99.52?mg?L(-1) and Vmax of 77.63?mg?L(-1) ?h(-1) . Scanning electron micrograms revealed the presence of extracellular polymeric secretions.","Reduction of hexavalent chromium by a novel Ochrobactrum sp. - microbial characteristics and reduction kinetics Abs: A Gram negative hexavalent chromium (Cr(VI)) reducing bacteria, Ochrobactrum sp. Cr-B4 (genbank accession number: JF824998) was isolated from the aerator water of an activated sludge process of a wastewater treatment facility of a dye and pigment based specialty chemical industry. It showed a resistance for 1000?mg?L(-1) Cr(VI). It exhibited resistance against other heavy metal ions like Ni(2+) (900?mg?L(-1) ), Cu(2+) (500?mg?L(-1) ), Pb(2+) (800?mg?L(-1) ), and Cd(2+) (250?mg?L(-1) ), Zn(2+) (700?mg?L(-1) ), Fe(3+) (800?mg?L(-1) ), and against selected antibiotics. Cr-B4 could efficiently reduce 200?mg?L(-1) Cr(VI) completely in nutrient and LB media and could convert Cr(VI) to Cr(III) efficiently. Cr(VI) reduction in nutrient media followed allosteric enzyme kinetics with Km values of 59.39?mg?L(-1) and Vmax values of 47.03?mg?L(-1) ?h(-1) . The reduction in LB media followed Michaelis-Menten kinetics with Km values of 99.52?mg?L(-1) and Vmax of 77.63?mg?L(-1) ?h(-1) . Scanning electron micrograms revealed the presence of extracellular polymeric secretions."
1786236,Montes et al. 2013,"Spectroscopic determination of the toxicity, absorption, reduction, and translocation of Cr(VI) in two Magnoliopsida species","Hexavalent chromium is a contaminant highly mobile in the environment that is toxic for plants at low concentrations. In this work, the physiological response of Convolvulus arvensis and Medicago truncatula plants to Cr(VI) treatments was compared. C. arvensis is a potential Cr hyperaccumulator well adapted to semiarid conditions that biotransform Cr(VI) to the less toxic Cr(III). M. truncatula is a model plant well adapted to semiarid conditions with a well studied genetic response to heavy metal stress. The results demonstrated that C. arvensis is more tolerant to Cr toxicity and has a higher Cr translocation to the leaves. The inductively coupled plasma optical emission spectroscopy results showed that C. arvensis plants treated with 10 mg Cr(VI) L(-1) accumulated 1512, 210, and 131 mg Cr kg(-1) in roots, stems, and leaves, respectively. While M. truncatula plants treated with the same Cr(VI) concentration accumulated 1081, 331, and 44 (mg Cr kg(-1)) in roots, stems, and leaves, respectively. Enzymatic assays demonstrated that Cr(VI) decreased ascorbate peroxidase activity and increased catalase activity in M. truncatula, while an opposite response was found in C. arvensis. The x-ray absorption spectroscopy studies showed that both plant species reduced Cr(VI) to the less toxic Cr(III).","Spectroscopic determination of the toxicity, absorption, reduction, and translocation of Cr(VI) in two Magnoliopsida species Abs: Hexavalent chromium is a contaminant highly mobile in the environment that is toxic for plants at low concentrations. In this work, the physiological response of Convolvulus arvensis and Medicago truncatula plants to Cr(VI) treatments was compared. C. arvensis is a potential Cr hyperaccumulator well adapted to semiarid conditions that biotransform Cr(VI) to the less toxic Cr(III). M. truncatula is a model plant well adapted to semiarid conditions with a well studied genetic response to heavy metal stress. The results demonstrated that C. arvensis is more tolerant to Cr toxicity and has a higher Cr translocation to the leaves. The inductively coupled plasma optical emission spectroscopy results showed that C. arvensis plants treated with 10 mg Cr(VI) L(-1) accumulated 1512, 210, and 131 mg Cr kg(-1) in roots, stems, and leaves, respectively. While M. truncatula plants treated with the same Cr(VI) concentration accumulated 1081, 331, and 44 (mg Cr kg(-1)) in roots, stems, and leaves, respectively. Enzymatic assays demonstrated that Cr(VI) decreased ascorbate peroxidase activity and increased catalase activity in M. truncatula, while an opposite response was found in C. arvensis. The x-ray absorption spectroscopy studies showed that both plant species reduced Cr(VI) to the less toxic Cr(III)."
1786235,Molokwane and  Chirwa 2013,Modelling biological Cr(VI) reduction in aquifer microcosm column systems,"Several chrome processing facilities in South Africa release hexavalent chromium (Cr(VI)) into groundwater resources. Pump-and-treat remediation processes have been implemented at some of the sites but have not been successful in reducing contamination levels. The current study is aimed at developing an environmentally friendly, cost-effective and self-sustained biological method to curb the spread of chromium at the contaminated sites. An indigenous Cr(VI)-reducing mixed culture of bacteria was demonstrated to reduce high levels of Cr(VI) in laboratory samples. The effect of Cr(VI) on the removal rate was evaluated at concentrations up to 400 mg/L. Following the detailed evaluation of fundamental processes for biological Cr(VI) reduction, a predictive model for Cr(VI) breakthrough through aquifer microcosm reactors was developed. The reaction rate in batch followed non-competitive rate kinetics with a Cr(VI) inhibition threshold concentration of approximately 99 mg/L. This study evaluates the application of the kinetic parameters determined in the batch reactors to the continuous flow process. The model developed from advection-reaction rate kinetics in a porous media fitted best the effluent Cr(VI) concentration. The model was also used to elucidate the logistic nature of biomass growth in the reactor systems.","Modelling biological Cr(VI) reduction in aquifer microcosm column systems Abs: Several chrome processing facilities in South Africa release hexavalent chromium (Cr(VI)) into groundwater resources. Pump-and-treat remediation processes have been implemented at some of the sites but have not been successful in reducing contamination levels. The current study is aimed at developing an environmentally friendly, cost-effective and self-sustained biological method to curb the spread of chromium at the contaminated sites. An indigenous Cr(VI)-reducing mixed culture of bacteria was demonstrated to reduce high levels of Cr(VI) in laboratory samples. The effect of Cr(VI) on the removal rate was evaluated at concentrations up to 400 mg/L. Following the detailed evaluation of fundamental processes for biological Cr(VI) reduction, a predictive model for Cr(VI) breakthrough through aquifer microcosm reactors was developed. The reaction rate in batch followed non-competitive rate kinetics with a Cr(VI) inhibition threshold concentration of approximately 99 mg/L. This study evaluates the application of the kinetic parameters determined in the batch reactors to the continuous flow process. The model developed from advection-reaction rate kinetics in a porous media fitted best the effluent Cr(VI) concentration. The model was also used to elucidate the logistic nature of biomass growth in the reactor systems."
1786234,Mizzouri et al. 2013,"Individual and combined effects of organic, toxic, and hydraulic shocks on sequencing batch reactor in treating petroleum refinery wastewater","This study analyzes the effects of toxic, hydraulic, and organic shocks on the performance of a lab-scale sequencing batch reactor (SBR) with a capacity of 5L. Petroleum refinery wastewater (PRWW) was treated with an organic loading rate (OLR) of approximately 0.3 kg chemical oxygen demand (COD)/kg MLSSd at 12.8h hydraulic retention time (HRT). A considerable variation in the COD was observed for organic, toxic, hydraulic, and combined shocks, and the worst values observed were 68.9, 77.1, 70.2, and 57.8%, respectively. Improved control of toxic shock loads of 10 and 20mg/L of chromium (VI) was identified. The system was adversely affected by the organic shock when a shock load thrice the normal value was used, and this behavior was repeated when the hydraulic shock was 4.8h HRT. The empirical recovery period was greater than the theoretical period because of the inhibitory effects of phenols, sulfides, high oil, and grease in the PRWW. The system recovery rates from the shocks were in the following order: toxic, organic, hydraulic, and combined shocks. System failure occurred when the combined shocks of organic and hydraulic were applied. The system was resumed by replacing the PRWW with glucose, and the OLR was reduced to half its initial value.","Individual and combined effects of organic, toxic, and hydraulic shocks on sequencing batch reactor in treating petroleum refinery wastewater Abs: This study analyzes the effects of toxic, hydraulic, and organic shocks on the performance of a lab-scale sequencing batch reactor (SBR) with a capacity of 5L. Petroleum refinery wastewater (PRWW) was treated with an organic loading rate (OLR) of approximately 0.3 kg chemical oxygen demand (COD)/kg MLSSd at 12.8h hydraulic retention time (HRT). A considerable variation in the COD was observed for organic, toxic, hydraulic, and combined shocks, and the worst values observed were 68.9, 77.1, 70.2, and 57.8%, respectively. Improved control of toxic shock loads of 10 and 20mg/L of chromium (VI) was identified. The system was adversely affected by the organic shock when a shock load thrice the normal value was used, and this behavior was repeated when the hydraulic shock was 4.8h HRT. The empirical recovery period was greater than the theoretical period because of the inhibitory effects of phenols, sulfides, high oil, and grease in the PRWW. The system recovery rates from the shocks were in the following order: toxic, organic, hydraulic, and combined shocks. System failure occurred when the combined shocks of organic and hydraulic were applied. The system was resumed by replacing the PRWW with glucose, and the OLR was reduced to half its initial value."
1786233,Mishra et al. 2013,Transcriptomic analysis provides insights on hexavalent chromium induced DNA double strand breaks and their possible repair in midgut cells of Drosophila melanogaster larvae,"Hexavalent chromium [Cr(VI)] is a well known mutagen and carcinogen. Since genomic instability due to generation of double strand breaks (DSBs) is causally linked to carcinogenesis, we tested a hypothesis that Cr(VI) causes in vivo generation of DSBs and elicits DNA damage response. We fed repair proficient Drosophila melanogaster (Oregon R(+)) larvae Cr(VI) (20.0?g/ml) mixed food for 24 and 48h and observed a significant (p&lt;0.05) induction of DSBs in their midgut cells after 48h using neutral Comet assay. Global gene expression profiling in Cr(VI)-exposed Oregon R(+) larvae unveiled mis-regulation of DSBs responsive repair genes both after 24 and 48h. In vivo generation of DSBs in exposed Drosophila was confirmed by an increased pH2Av immunostaining along with the activation of cell cycle regulation genes. Analysis of mis-regulated genes grouped under DSB response by GOEAST indicated the participation of non-homologous end joining (NHEJ) DSB repair pathway. We selected two strains, one mutant (ligIV) and another ku80-RNAi (knockdown of ku80), whose functions are essentially linked to NHEJ-DSB repair pathway. As a proof of principle, we compared the DSBs generation in larvae of these two strains with that of repair proficient Oregon R(+). Along with this, DSBs generation in spn-A and okr [essential genes in homologous recombination repair (HR) pathway] mutants was also tested for the possible involvement of HR-DSB repair. A significantly increased DSBs generation in the exposed ku80-RNAi and ligIV (mutant) larvae because of impaired repair, concomitant with an insignificant DSBs generation in okr and spn-A mutant larvae indicates an active participation of NHEJ repair pathway. The study, first of its kind to our knowledge, while providing evidences for in vivo generation of DSBs in Cr(VI) exposed Drosophila larvae, assumes significance for its relevance to higher organisms due to causal link between DSB generation and Cr(VI)-induced carcinogenesis.","Transcriptomic analysis provides insights on hexavalent chromium induced DNA double strand breaks and their possible repair in midgut cells of Drosophila melanogaster larvae Abs: Hexavalent chromium [Cr(VI)] is a well known mutagen and carcinogen. Since genomic instability due to generation of double strand breaks (DSBs) is causally linked to carcinogenesis, we tested a hypothesis that Cr(VI) causes in vivo generation of DSBs and elicits DNA damage response. We fed repair proficient Drosophila melanogaster (Oregon R(+)) larvae Cr(VI) (20.0?g/ml) mixed food for 24 and 48h and observed a significant (p&lt;0.05) induction of DSBs in their midgut cells after 48h using neutral Comet assay. Global gene expression profiling in Cr(VI)-exposed Oregon R(+) larvae unveiled mis-regulation of DSBs responsive repair genes both after 24 and 48h. In vivo generation of DSBs in exposed Drosophila was confirmed by an increased pH2Av immunostaining along with the activation of cell cycle regulation genes. Analysis of mis-regulated genes grouped under DSB response by GOEAST indicated the participation of non-homologous end joining (NHEJ) DSB repair pathway. We selected two strains, one mutant (ligIV) and another ku80-RNAi (knockdown of ku80), whose functions are essentially linked to NHEJ-DSB repair pathway. As a proof of principle, we compared the DSBs generation in larvae of these two strains with that of repair proficient Oregon R(+). Along with this, DSBs generation in spn-A and okr [essential genes in homologous recombination repair (HR) pathway] mutants was also tested for the possible involvement of HR-DSB repair. A significantly increased DSBs generation in the exposed ku80-RNAi and ligIV (mutant) larvae because of impaired repair, concomitant with an insignificant DSBs generation in okr and spn-A mutant larvae indicates an active participation of NHEJ repair pathway. The study, first of its kind to our knowledge, while providing evidences for in vivo generation of DSBs in Cr(VI) exposed Drosophila larvae, assumes significance for its relevance to higher organisms due to causal link between DSB generation and Cr(VI)-induced carcinogenesis."
1786232,Metters et al. 2013,Fabrication of co-planar screen printed microband electrodes,"We demonstrate the first example of the fabrication of co-planar 50 ?m (width) screen printed graphite microbands (length: 20 mm), fabricated entirely via screen printing which are characterised both microscopically and electrochemically via cyclic voltammetry and evaluated towards the sensing of NADH offering a competitive limit of detection (3?) of 0.24 ?M. The fabricated electrodes are also shown to be extended to gold screen printed microbands which are evaluated towards the sensing of chromium(VI) offering a limit of detection (3?) of 2.65 ?M. These microbands are seen to be the first produced entirely through screen printed technology potentially allowing disposable, mass produced microbands to be realised.","Fabrication of co-planar screen printed microband electrodes Abs: We demonstrate the first example of the fabrication of co-planar 50 ?m (width) screen printed graphite microbands (length: 20 mm), fabricated entirely via screen printing which are characterised both microscopically and electrochemically via cyclic voltammetry and evaluated towards the sensing of NADH offering a competitive limit of detection (3?) of 0.24 ?M. The fabricated electrodes are also shown to be extended to gold screen printed microbands which are evaluated towards the sensing of chromium(VI) offering a limit of detection (3?) of 2.65 ?M. These microbands are seen to be the first produced entirely through screen printed technology potentially allowing disposable, mass produced microbands to be realised."
1786231,Menz et al. ,Toxicity testing with luminescent bacteria - Characterization of an automated method for the combined assessment of acute and chronic effects,"The luminescent bacteria test according to EN ISO 11348 is frequently applied in (eco) toxicity testing and is applicable for a huge variety of environmental and industrial samples. A big disadvantage of this method is the very short exposure time, which is expressed in a low sensitivity in regard to substances with a delayed effect. Chronic effects, i.e. interference with cell growth, cannot be assessed with this conventional standard method. The goal of this research was to develop an automated testing system for long term toxicity towards the luminescent bacteria Vibrio fischeri by implementing microtitration-based instrumentation. The optimized method, hereinafter referred to as &quot;kinetic luminescent bacteria test&quot;, can be described as a miniaturized combination of the conventional short-term luminescence inhibition test according to EN ISO 11348 and the Photobacterium phosphoreum growth inhibition test (DIN 38412-37). The validation procedure included the evaluation of six reference compounds (3,4-Dichloroaniline, 3,5-Dichlorophenol, Chloramphenicol, Streptomycin sulfate, Potassium dichromate, Zinc sulfate heptahydrate) and three different endpoints that are acute luminescence inhibition (acute LI) after 30min, chronic luminescence inhibition (chronic LI) after 24h and growth inhibition (GI) after 14h. The optimized method allows the assessment of acute and chronic effects within one test, by what a misinterpretation of the toxicity of substances with delayed bacterial toxicity can be prevented, without abandoning most of the advantages of the conventional short-term test. Therefore, the kinetic luminescent bacteria test is exceptional as an initial screening test for environmental samples or substances with unknown (eco) toxicological characteristics.","Toxicity testing with luminescent bacteria - Characterization of an automated method for the combined assessment of acute and chronic effects Abs: The luminescent bacteria test according to EN ISO 11348 is frequently applied in (eco) toxicity testing and is applicable for a huge variety of environmental and industrial samples. A big disadvantage of this method is the very short exposure time, which is expressed in a low sensitivity in regard to substances with a delayed effect. Chronic effects, i.e. interference with cell growth, cannot be assessed with this conventional standard method. The goal of this research was to develop an automated testing system for long term toxicity towards the luminescent bacteria Vibrio fischeri by implementing microtitration-based instrumentation. The optimized method, hereinafter referred to as &quot;kinetic luminescent bacteria test&quot;, can be described as a miniaturized combination of the conventional short-term luminescence inhibition test according to EN ISO 11348 and the Photobacterium phosphoreum growth inhibition test (DIN 38412-37). The validation procedure included the evaluation of six reference compounds (3,4-Dichloroaniline, 3,5-Dichlorophenol, Chloramphenicol, Streptomycin sulfate, Potassium dichromate, Zinc sulfate heptahydrate) and three different endpoints that are acute luminescence inhibition (acute LI) after 30min, chronic luminescence inhibition (chronic LI) after 24h and growth inhibition (GI) after 14h. The optimized method allows the assessment of acute and chronic effects within one test, by what a misinterpretation of the toxicity of substances with delayed bacterial toxicity can be prevented, without abandoning most of the advantages of the conventional short-term test. Therefore, the kinetic luminescent bacteria test is exceptional as an initial screening test for environmental samples or substances with unknown (eco) toxicological characteristics."
1786230,Matusik and  Bajda 2013,Immobilization and reduction of hexavalent chromium in the interlayer space of positively charged kaolinites,This work was designed to investigate the sorption equilibrium and kinetics of modified kaolinites of different structural order toward Cr(VI). The key reaction of modification involved an iodomethane quaternization of the mineral previously interlayer grafted with triethanolamine. This induced positively charged centers (PCNs) associated with nitrogens of ammonium salt molecules formed in the interlayer space. The positive charge was compensated by mobile iodide anions which could be ion-exchanged. Results reveal a significant increase in sorption capacity as compared to raw kaolinites and show that the sorption takes place exclusively in the interlayer space which proved to be accessible for the Cr(VI). The amount of sorbed Cr(VI) depends on the PCN content resulting from the kaolinites reactivity influenced by their structural order. An ion-exchange mechanism followed by Cr(VI) to Cr(III) reduction by iodide is proposed. The amount of initially sorbed Cr(VI) and its anionic form is strongly influenced by the pH. Desorption experiments showed that only the Cr(VI) which was not reduced (~30%) was released to the solution.,Immobilization and reduction of hexavalent chromium in the interlayer space of positively charged kaolinites Abs: This work was designed to investigate the sorption equilibrium and kinetics of modified kaolinites of different structural order toward Cr(VI). The key reaction of modification involved an iodomethane quaternization of the mineral previously interlayer grafted with triethanolamine. This induced positively charged centers (PCNs) associated with nitrogens of ammonium salt molecules formed in the interlayer space. The positive charge was compensated by mobile iodide anions which could be ion-exchanged. Results reveal a significant increase in sorption capacity as compared to raw kaolinites and show that the sorption takes place exclusively in the interlayer space which proved to be accessible for the Cr(VI). The amount of sorbed Cr(VI) depends on the PCN content resulting from the kaolinites reactivity influenced by their structural order. An ion-exchange mechanism followed by Cr(VI) to Cr(III) reduction by iodide is proposed. The amount of initially sorbed Cr(VI) and its anionic form is strongly influenced by the pH. Desorption experiments showed that only the Cr(VI) which was not reduced (~30%) was released to the solution.
1786229,Marzouk et al. 2013,Adsorption of chromium onto activated alumina: kinetics and thermodynamics studies,"In this study, the removal of chromium (VI) by adsorption on activated alumina was investigated and the results were fitted to Langmuir, Freundlich, Dubinin-Redushkevich, and Temkin adsorption models at various temperatures. The constants of each model were evaluated depending on temperature. Thermodynamic parameters for the adsorption system were determined at 10, 25 and 40 degrees C. (deltaH degrees = -21.18 kJ x mol(-1); deltaG degrees = -8.75 to -7.43 kJ x mol(-1) and deltaS degrees = -0.043 kJ x K(-1) x mol(-1)). The obtained values showed that chromium (VI) adsorption is a spontaneous and exothermic process. The kinetic process was evaluated by first-order, second-order and Elovich kinetic models.","Adsorption of chromium onto activated alumina: kinetics and thermodynamics studies Abs: In this study, the removal of chromium (VI) by adsorption on activated alumina was investigated and the results were fitted to Langmuir, Freundlich, Dubinin-Redushkevich, and Temkin adsorption models at various temperatures. The constants of each model were evaluated depending on temperature. Thermodynamic parameters for the adsorption system were determined at 10, 25 and 40 degrees C. (deltaH degrees = -21.18 kJ x mol(-1); deltaG degrees = -8.75 to -7.43 kJ x mol(-1) and deltaS degrees = -0.043 kJ x K(-1) x mol(-1)). The obtained values showed that chromium (VI) adsorption is a spontaneous and exothermic process. The kinetic process was evaluated by first-order, second-order and Elovich kinetic models."
1786228,Luther et al. 2013,Study of the thermodynamics of chromium(III) and chromium(VI) binding to iron(II/III)oxide or magnetite or ferrite and magnanese(II) iron (III) oxide or jacobsite or manganese ferrite nanoparticles,"Removal of chromium(III) or (VI) from aqueous solution was achieved using Fe3O4, and MnFe2O4 nanomaterials. The nanomaterials were synthesized using a precipitation method and characterized using XRD. The size of the nanomaterials was determined to be 22.4±0.9 nm (Fe3O4) and 15.5±0.5 nm (MnFe2O4). The optimal binding pH for chromium(III) and chromium(VI) were pH 6 and pH 3. Isotherm studies were performed, under light and dark conditions, to determine the capacity of the nanomaterials. The capacities for the light studies with MnFe2O4 and Fe3O4 were determined to be 7.189 and 10.63 mg/g, respectively, for chromium(III). The capacities for the light studies with MnFe2O4 and Fe3O4 were 3.21 and 3.46 mg/g, respectively, for chromium(VI). Under dark reaction conditions the binding of chromium(III) to the MnFe2O4 and Fe3O4 nanomaterials were 5.74 and 15.9 mg/g, respectively. The binding capacity for the binding of chromium(VI) to MnFe2O4 and Fe3O4 under dark reaction conditions were 3.87 and 8.54 mg/g, respectively. The thermodynamics for the reactions showed negative ?G values, and positive ?H values. The ?S values were positive for the binding of chromium(III) and for chromium(VI) binding under dark reaction conditions. The ?S values for chromium(VI) binding under the light reaction conditions were determined to be negative.","Study of the thermodynamics of chromium(III) and chromium(VI) binding to iron(II/III)oxide or magnetite or ferrite and magnanese(II) iron (III) oxide or jacobsite or manganese ferrite nanoparticles Abs: Removal of chromium(III) or (VI) from aqueous solution was achieved using Fe3O4, and MnFe2O4 nanomaterials. The nanomaterials were synthesized using a precipitation method and characterized using XRD. The size of the nanomaterials was determined to be 22.4±0.9 nm (Fe3O4) and 15.5±0.5 nm (MnFe2O4). The optimal binding pH for chromium(III) and chromium(VI) were pH 6 and pH 3. Isotherm studies were performed, under light and dark conditions, to determine the capacity of the nanomaterials. The capacities for the light studies with MnFe2O4 and Fe3O4 were determined to be 7.189 and 10.63 mg/g, respectively, for chromium(III). The capacities for the light studies with MnFe2O4 and Fe3O4 were 3.21 and 3.46 mg/g, respectively, for chromium(VI). Under dark reaction conditions the binding of chromium(III) to the MnFe2O4 and Fe3O4 nanomaterials were 5.74 and 15.9 mg/g, respectively. The binding capacity for the binding of chromium(VI) to MnFe2O4 and Fe3O4 under dark reaction conditions were 3.87 and 8.54 mg/g, respectively. The thermodynamics for the reactions showed negative ?G values, and positive ?H values. The ?S values were positive for the binding of chromium(III) and for chromium(VI) binding under dark reaction conditions. The ?S values for chromium(VI) binding under the light reaction conditions were determined to be negative."
1786227,Luczak and  Zhitkovich ,"Role of direct reactivity with metals in chemoprotection by N-acetylcysteine against chromium(VI), cadmium(II), and cobalt(II)","The antioxidant N-acetylcysteine (NAC) is widely used for the assessment of the role of reactive oxygen species (ROS) in various biological processes and adverse drug reactions. NAC has been found to effectively inhibit the toxicity of carcinogenic metals, which was attributed to its potent ROS-suppressive properties. However, the absence of redox activity among some metals and findings from genetic models suggested a more diverse, smaller role of oxidative stress in metal toxicity. Here, we examined mechanisms of chemoprotection by NAC against Cd(II), Co(II), and Cr(VI) in human cells. We found that NAC displayed a broad-spectrum chemoprotective activity against all three metals, including suppression of cytotoxicity, apoptosis, p53 activation, and HSP72 and HIF-1? upregulation. Cytoprotection by NAC was independent of cellular glutathione. NAC strongly inhibited the uptake of all three metals in histologically different types of human cells, explaining its high chemoprotective potential. A loss of Cr(VI) accumulation by cells was caused by NAC-mediated extracellular reduction of chromate to membrane-impermeative Cr(III). Suppression of Co(II) uptake resulted from a rapid formation of Co(II)-NAC conjugates that were unable to enter cells. Our results demonstrate that NAC acts through more than one mechanism in preventing metal toxicity and its chemoprotective activity can be completely ROS-independent. Good clinical safety and effectiveness in Co(II) sequestration suggest that NAC could be useful in the prevention of tissue accumulation and toxic effects of Co ions released by cobalt-chromium hip prostheses.","Role of direct reactivity with metals in chemoprotection by N-acetylcysteine against chromium(VI), cadmium(II), and cobalt(II) Abs: The antioxidant N-acetylcysteine (NAC) is widely used for the assessment of the role of reactive oxygen species (ROS) in various biological processes and adverse drug reactions. NAC has been found to effectively inhibit the toxicity of carcinogenic metals, which was attributed to its potent ROS-suppressive properties. However, the absence of redox activity among some metals and findings from genetic models suggested a more diverse, smaller role of oxidative stress in metal toxicity. Here, we examined mechanisms of chemoprotection by NAC against Cd(II), Co(II), and Cr(VI) in human cells. We found that NAC displayed a broad-spectrum chemoprotective activity against all three metals, including suppression of cytotoxicity, apoptosis, p53 activation, and HSP72 and HIF-1? upregulation. Cytoprotection by NAC was independent of cellular glutathione. NAC strongly inhibited the uptake of all three metals in histologically different types of human cells, explaining its high chemoprotective potential. A loss of Cr(VI) accumulation by cells was caused by NAC-mediated extracellular reduction of chromate to membrane-impermeative Cr(III). Suppression of Co(II) uptake resulted from a rapid formation of Co(II)-NAC conjugates that were unable to enter cells. Our results demonstrate that NAC acts through more than one mechanism in preventing metal toxicity and its chemoprotective activity can be completely ROS-independent. Good clinical safety and effectiveness in Co(II) sequestration suggest that NAC could be useful in the prevention of tissue accumulation and toxic effects of Co ions released by cobalt-chromium hip prostheses."
1786226,López-Téllez et al. 2013,Green method to form iron oxide nanorods in orange peels for chromium(VI) reduction,"A green method for synthesizing iron oxide nanorods within orange peel pith has been developed. Orange peel pith functions as both a support and a reducing agent for iron ions. The nanorods were characterized using scanning electron microscopy, energy dispersive X-ray spectroscopy, transmission electron microscopy and X-ray photoelectron spectroscopy. Results of the characterization indicate that iron is deposited on the surface of orange peel primarily in the form of iron, iron(II) oxide and magnetite. The nanoparticles grow to form nanorods in the range of 20-40 nm of diameter. The biocomposite was then tested for Cr(VI) reduction and removal from aqueous solutions, exhibiting removals as high as 96% for concentrations of 10 mg/L and 76% for 50 mg/L, which is almost 4 times the removal capacity of orange peel alone.","Green method to form iron oxide nanorods in orange peels for chromium(VI) reduction Abs: A green method for synthesizing iron oxide nanorods within orange peel pith has been developed. Orange peel pith functions as both a support and a reducing agent for iron ions. The nanorods were characterized using scanning electron microscopy, energy dispersive X-ray spectroscopy, transmission electron microscopy and X-ray photoelectron spectroscopy. Results of the characterization indicate that iron is deposited on the surface of orange peel primarily in the form of iron, iron(II) oxide and magnetite. The nanoparticles grow to form nanorods in the range of 20-40 nm of diameter. The biocomposite was then tested for Cr(VI) reduction and removal from aqueous solutions, exhibiting removals as high as 96% for concentrations of 10 mg/L and 76% for 50 mg/L, which is almost 4 times the removal capacity of orange peel alone."
1786225,Liu et al. 2013,Polyaniline/cellulose fiber composite prepared using persulfate as oxidant for Cr(VI)-detoxification,"Cellulose fibers were engineered by in situ oxidative polymerization of aniline using ammonium persulfate as oxidant/initiator. The polyaniline/cellulose fiber composite was used for the treatment of Cr(VI)-contaminated water, and its effect was evaluated. Under the conditions studied, the composite exhibited very high water detoxification efficiency, as a result of reduction of Cr(VI) to Cr(III) in combination with adsorption of the Cr(III) onto the cellulosic substrate. Cellulose fibers used in the study served two purposes simultaneously, i.e., carrier of polyaniline and the adsorbent for Cr(III). The complexation of polyaniline with cellulose fibers provided synergistic effects on Cr(VI)-detoxification.","Polyaniline/cellulose fiber composite prepared using persulfate as oxidant for Cr(VI)-detoxification Abs: Cellulose fibers were engineered by in situ oxidative polymerization of aniline using ammonium persulfate as oxidant/initiator. The polyaniline/cellulose fiber composite was used for the treatment of Cr(VI)-contaminated water, and its effect was evaluated. Under the conditions studied, the composite exhibited very high water detoxification efficiency, as a result of reduction of Cr(VI) to Cr(III) in combination with adsorption of the Cr(III) onto the cellulosic substrate. Cellulose fibers used in the study served two purposes simultaneously, i.e., carrier of polyaniline and the adsorbent for Cr(III). The complexation of polyaniline with cellulose fibers provided synergistic effects on Cr(VI)-detoxification."
1786224,Licursi and  Gómez 2013,Short-term toxicity of hexavalent-chromium to epipsammic diatoms of a microtidal estuary (Río de la Plata): responses from the individual cell to the community structure,"Diatoms are an integral and often dominant component of the benthic microalgal assemblage in estuarine and shallow coastal environments. Different toxic substances discharged into these ecosystems persist in the water, sediments, and biota for long periods. Among these pernicious agents, the toxicity in diatoms by metal is linked to different steps in the transmembrane and internal movements of the toxicant, causing perturbations in the normal structural and functional cellular components. These changes constitute an early, nontaxonomic warning signal that could potentially serve as an indicator of this type of pollution. The aim of this work was to study the environment-reflecting short-term responses at different levels of organization of epipsammic diatoms from the Río de la Plata estuary, Argentina that had been exposed to hexavalent chromium within experimental microcosms. To this end we monitored: (i) changes in the proportion of the diatoms in relation to other algal groups at the biofilm community level; (ii) shifts in species composition at the diatom-assemblage level; (iii) projected changes in the densities of the most representative species at the population level through comparison of relative growth rates and generation times; and (iv) the cytological changes at the cellular and subcellular levels as indicated by the appearance of teratological effects on individuals and nuclear alterations. The epipsammic biofilms were exposed for 96 h to chromium at a concentration similar to that measured in highly impacted sites along the coast (80 ?g L?¹). Chromium pollution, at this concentration and short exposure time did not affect the algal biomass and density of these mature biofilms. The biofilm composition, however, did change, as reflected in a decline in cyanophytes and an increment in the proportions of diatoms and chlorophytes; with Hippodonta hungarica, Navicula novaesiberica, Nitzschia palea, and Sellaphora pupula being the most frequent and abundant species. The most notable shifts related to chromium exposure were a decrease in the relative abundance of H. hungarica and a significant increase in the proportion of N. palea. Moreover, the species analyzed in the treatment microcosms showed higher growth rates than in the controls--N. palea grew faster, while H. hungarica replicated more slowly. The total nuclear abnormalities--as recorded in Fallacia pygmaea and N. novaesiberica--were significantly higher in the treatment microcosms; whereas in N. palea, the dominant species in treatment microcosms, neither nuclear alterations nor abnormal frustules were observed.","Short-term toxicity of hexavalent-chromium to epipsammic diatoms of a microtidal estuary (Río de la Plata): responses from the individual cell to the community structure Abs: Diatoms are an integral and often dominant component of the benthic microalgal assemblage in estuarine and shallow coastal environments. Different toxic substances discharged into these ecosystems persist in the water, sediments, and biota for long periods. Among these pernicious agents, the toxicity in diatoms by metal is linked to different steps in the transmembrane and internal movements of the toxicant, causing perturbations in the normal structural and functional cellular components. These changes constitute an early, nontaxonomic warning signal that could potentially serve as an indicator of this type of pollution. The aim of this work was to study the environment-reflecting short-term responses at different levels of organization of epipsammic diatoms from the Río de la Plata estuary, Argentina that had been exposed to hexavalent chromium within experimental microcosms. To this end we monitored: (i) changes in the proportion of the diatoms in relation to other algal groups at the biofilm community level; (ii) shifts in species composition at the diatom-assemblage level; (iii) projected changes in the densities of the most representative species at the population level through comparison of relative growth rates and generation times; and (iv) the cytological changes at the cellular and subcellular levels as indicated by the appearance of teratological effects on individuals and nuclear alterations. The epipsammic biofilms were exposed for 96 h to chromium at a concentration similar to that measured in highly impacted sites along the coast (80 ?g L?¹). Chromium pollution, at this concentration and short exposure time did not affect the algal biomass and density of these mature biofilms. The biofilm composition, however, did change, as reflected in a decline in cyanophytes and an increment in the proportions of diatoms and chlorophytes; with Hippodonta hungarica, Navicula novaesiberica, Nitzschia palea, and Sellaphora pupula being the most frequent and abundant species. The most notable shifts related to chromium exposure were a decrease in the relative abundance of H. hungarica and a significant increase in the proportion of N. palea. Moreover, the species analyzed in the treatment microcosms showed higher growth rates than in the controls--N. palea grew faster, while H. hungarica replicated more slowly. The total nuclear abnormalities--as recorded in Fallacia pygmaea and N. novaesiberica--were significantly higher in the treatment microcosms; whereas in N. palea, the dominant species in treatment microcosms, neither nuclear alterations nor abnormal frustules were observed."
1786223,Liao et al. ,Physicochemical and biological quality of soil in hexavalent chromium-contaminated soils as affected by chemical and microbial remediation,"Chemical and microbial methods are the main remediation technologies for chromium-contaminated soil. These technologies have progressed rapidly in recent years; however, there is still a lack of methods for evaluating the chemical and biological quality of soil after different remediation technologies have been applied. In this paper, microbial remediation with indigenous bacteria and chemical remediation with ferrous sulphate were used for the remediation of soils contaminated with Cr(VI) at two levels (80 and 1,276 mg kg(-1)) through a column leaching experiment. After microbial remediation with indigenous bacteria, the average concentration of water-soluble Cr(VI) in the soils was reduced to less than 5.0 mg kg(-1). Soil quality was evaluated based on 11 soil properties and the fuzzy comprehensive assessment method, including fuzzy mathematics and correlative analysis. The chemical fertility quality index was improved by one grade using microbial remediation with indigenous bacteria, and the biological fertility quality index increased by at least a factor of 6. Chemical remediation with ferrous sulphate, however, resulted in lower levels of available phosphorus, dehydrogenase, catalase and polyphenol oxidase. The result showed that microbial remediation with indigenous bacteria was more effective for remedying Cr(VI)-contaminated soils with high pH value than chemical remediation with ferrous sulphate. In addition, the fuzzy comprehensive evaluation method was proven to be a useful tool for monitoring the quality change in chromium-contaminated soils.","Physicochemical and biological quality of soil in hexavalent chromium-contaminated soils as affected by chemical and microbial remediation Abs: Chemical and microbial methods are the main remediation technologies for chromium-contaminated soil. These technologies have progressed rapidly in recent years; however, there is still a lack of methods for evaluating the chemical and biological quality of soil after different remediation technologies have been applied. In this paper, microbial remediation with indigenous bacteria and chemical remediation with ferrous sulphate were used for the remediation of soils contaminated with Cr(VI) at two levels (80 and 1,276 mg kg(-1)) through a column leaching experiment. After microbial remediation with indigenous bacteria, the average concentration of water-soluble Cr(VI) in the soils was reduced to less than 5.0 mg kg(-1). Soil quality was evaluated based on 11 soil properties and the fuzzy comprehensive assessment method, including fuzzy mathematics and correlative analysis. The chemical fertility quality index was improved by one grade using microbial remediation with indigenous bacteria, and the biological fertility quality index increased by at least a factor of 6. Chemical remediation with ferrous sulphate, however, resulted in lower levels of available phosphorus, dehydrogenase, catalase and polyphenol oxidase. The result showed that microbial remediation with indigenous bacteria was more effective for remedying Cr(VI)-contaminated soils with high pH value than chemical remediation with ferrous sulphate. In addition, the fuzzy comprehensive evaluation method was proven to be a useful tool for monitoring the quality change in chromium-contaminated soils."
1786222,Li et al. 2013,"Molecular cloning and characterization of cat, gpx1 and Cu/Zn-sod genes in pengze crucian carp (Carassius auratus var. Pengze) and antioxidant enzyme modulation induced by hexavalent chromium in juveniles","Hexavalent chromium (Cr(6+)) is a common pollutant transient metal with high toxicity in the environment. The toxicological effects partly result from oxidative damage due to the production of excessive reactive oxygen species (ROS) in the reductive process of Cr(6+). To explore the influence of ROS induced directly by Cr(6+) on the oxidative stress generation and antioxidant system, the full length cDNAs of antioxidant-related genes cat, gpx1 and Cu/Zn-sod were successfully acquired from pengze crucian carp first and analyzed. Furthermore, the mRNA expression of the antioxidant genes encompassing catalase (cat), copper/zinc superoxide dismutase (Cu/Zn-sod) and glutathione peroxidase (gpx1), antioxidant enzyme activities of CAT, SOD, and GPx and total protein content were further studied in the gill, intestine and liver of pengze crucian carp (Carassius auratus var. Pengze) juveniles upon acute exposure to Cr(6+) at concentrations of 0.1, 1.0, 10 and 100 mg/L for 4 days. Differential significant changes of the antioxidant enzymes and gene expression were observed in different tissues. The findings contribute to better understanding the antioxidant mechanisms induced by Cr(6+) and selecting the organic-specific sensitive biomarkers to monitor the safety of the aquatic ecosystem.","Molecular cloning and characterization of cat, gpx1 and Cu/Zn-sod genes in pengze crucian carp (Carassius auratus var. Pengze) and antioxidant enzyme modulation induced by hexavalent chromium in juveniles Abs: Hexavalent chromium (Cr(6+)) is a common pollutant transient metal with high toxicity in the environment. The toxicological effects partly result from oxidative damage due to the production of excessive reactive oxygen species (ROS) in the reductive process of Cr(6+). To explore the influence of ROS induced directly by Cr(6+) on the oxidative stress generation and antioxidant system, the full length cDNAs of antioxidant-related genes cat, gpx1 and Cu/Zn-sod were successfully acquired from pengze crucian carp first and analyzed. Furthermore, the mRNA expression of the antioxidant genes encompassing catalase (cat), copper/zinc superoxide dismutase (Cu/Zn-sod) and glutathione peroxidase (gpx1), antioxidant enzyme activities of CAT, SOD, and GPx and total protein content were further studied in the gill, intestine and liver of pengze crucian carp (Carassius auratus var. Pengze) juveniles upon acute exposure to Cr(6+) at concentrations of 0.1, 1.0, 10 and 100 mg/L for 4 days. Differential significant changes of the antioxidant enzymes and gene expression were observed in different tissues. The findings contribute to better understanding the antioxidant mechanisms induced by Cr(6+) and selecting the organic-specific sensitive biomarkers to monitor the safety of the aquatic ecosystem."
1786221,Kyzas et al. ,On the simultaneous adsorption of a reactive dye and hexavalent chromium from aqueous solutions onto grafted chitosan,"In the present work, the simultaneous adsorption of Remazol Red 3BS (reactive dye) and Cr(VI) onto chitosan powder grafted with poly(ethylene imine) and cross-linked with epichlorohydrin is experimentally studied. Such a combination of a dye molecule and a heavy metal can be found in real/practical conditions of environmental pollutants' removal, so their mutual interaction on the adsorption efficiencies is very important. The experimental data revealed a competitive type of interaction between the dye molecule and heavy metal ion. An attempt is made to quantitatively describe the data through appropriate isotherms and kinetic equations. The data demonstrated that the common thermodynamic equilibrium is not obtained for the present problem and the final composition of the adsorbed phase depends also on the kinetics. A new scenario of irreversible kinetic-based equilibrium was introduced and examined in detail. None of the scenarios considered here is fully able to cover the whole data, so semi-empirical equations are introduced for their description. It is shown that further development of phenomenological models requires more complicated experimental protocols than simple simultaneous adsorption of the species.","On the simultaneous adsorption of a reactive dye and hexavalent chromium from aqueous solutions onto grafted chitosan Abs: In the present work, the simultaneous adsorption of Remazol Red 3BS (reactive dye) and Cr(VI) onto chitosan powder grafted with poly(ethylene imine) and cross-linked with epichlorohydrin is experimentally studied. Such a combination of a dye molecule and a heavy metal can be found in real/practical conditions of environmental pollutants' removal, so their mutual interaction on the adsorption efficiencies is very important. The experimental data revealed a competitive type of interaction between the dye molecule and heavy metal ion. An attempt is made to quantitatively describe the data through appropriate isotherms and kinetic equations. The data demonstrated that the common thermodynamic equilibrium is not obtained for the present problem and the final composition of the adsorbed phase depends also on the kinetics. A new scenario of irreversible kinetic-based equilibrium was introduced and examined in detail. None of the scenarios considered here is fully able to cover the whole data, so semi-empirical equations are introduced for their description. It is shown that further development of phenomenological models requires more complicated experimental protocols than simple simultaneous adsorption of the species."
1786220,Kumar et al. 2013,Genotoxicity and antioxidant enzyme activity induced by hexavalent chromium in Cyprinus carpio after in vivo exposure,"Abstract Fish, being an important native of the aquatic ecosystem, are exposed to multipollution states and are therefore considered as model organisms for ecotoxicological studies of aquatic pollutants, including metal toxicity. We investigated oxidative stress (OS) in liver, kidney and gill tissues through antioxidant enzyme activities and genotoxicity induced in whole blood and gill tissues through comet assay and micronucleus (MN) test in Cyprinus carpio after 96-hour in vivo static exposure to potassium dichromate at three sublethal (SL) test concentrations, including SL-I [93.95?mg/L, i.e. one quarter of half-maximal lethal concentration (LC50)], SL-II (187.9?mg/L, i.e. one half of LC50), and SL-III (281.85?mg/L, i.e. three quarters of LC50), along with a control. The 96-hour LC50 value for potassium dichromate was estimated to be 375.8?mg/L in a static system in the test species. Tissues samples were collected at 24, 48, 72 and 96 hours postexposure. Results indicated that the exposed fish experienced OS as characterized by significant (p?&lt;?0.05) variation in antioxidant enzyme activities, as compared to the control. Activities of superoxide dismutase and glutathione peroxidase increased, whereas activity of catalase decreased with the progression of the experiment. The mean percent DNA damage in comet tail and MN induction in gills and whole blood showed a concentration-dependent increase up to 96-hour exposure. The findings of this study would be helpful in organ-specific risk assessment of Cr(VI)-induced OS and genotoxicity in fishes.","Genotoxicity and antioxidant enzyme activity induced by hexavalent chromium in Cyprinus carpio after in vivo exposure Abs: Abstract Fish, being an important native of the aquatic ecosystem, are exposed to multipollution states and are therefore considered as model organisms for ecotoxicological studies of aquatic pollutants, including metal toxicity. We investigated oxidative stress (OS) in liver, kidney and gill tissues through antioxidant enzyme activities and genotoxicity induced in whole blood and gill tissues through comet assay and micronucleus (MN) test in Cyprinus carpio after 96-hour in vivo static exposure to potassium dichromate at three sublethal (SL) test concentrations, including SL-I [93.95?mg/L, i.e. one quarter of half-maximal lethal concentration (LC50)], SL-II (187.9?mg/L, i.e. one half of LC50), and SL-III (281.85?mg/L, i.e. three quarters of LC50), along with a control. The 96-hour LC50 value for potassium dichromate was estimated to be 375.8?mg/L in a static system in the test species. Tissues samples were collected at 24, 48, 72 and 96 hours postexposure. Results indicated that the exposed fish experienced OS as characterized by significant (p?&lt;?0.05) variation in antioxidant enzyme activities, as compared to the control. Activities of superoxide dismutase and glutathione peroxidase increased, whereas activity of catalase decreased with the progression of the experiment. The mean percent DNA damage in comet tail and MN induction in gills and whole blood showed a concentration-dependent increase up to 96-hour exposure. The findings of this study would be helpful in organ-specific risk assessment of Cr(VI)-induced OS and genotoxicity in fishes."
1786219,Kucza 2013,Flow injection analysis simulations and diffusion coefficient determination by stochastic and deterministic optimization methods,"Stochastic and deterministic simulations of dispersion in cylindrical channels on the Poiseuille flow have been presented. The random walk (stochastic) and the uniform dispersion (deterministic) models have been used for computations of flow injection analysis responses. These methods coupled with the genetic algorithm and the Levenberg-Marquardt optimization methods, respectively, have been applied for determination of diffusion coefficients. The diffusion coefficients of fluorescein sodium, potassium hexacyanoferrate and potassium dichromate have been determined by means of the presented methods and FIA responses that are available in literature. The best-fit results agree with each other and with experimental data thus validating both presented approaches.","Flow injection analysis simulations and diffusion coefficient determination by stochastic and deterministic optimization methods Abs: Stochastic and deterministic simulations of dispersion in cylindrical channels on the Poiseuille flow have been presented. The random walk (stochastic) and the uniform dispersion (deterministic) models have been used for computations of flow injection analysis responses. These methods coupled with the genetic algorithm and the Levenberg-Marquardt optimization methods, respectively, have been applied for determination of diffusion coefficients. The diffusion coefficients of fluorescein sodium, potassium hexacyanoferrate and potassium dichromate have been determined by means of the presented methods and FIA responses that are available in literature. The best-fit results agree with each other and with experimental data thus validating both presented approaches."
1786218,Kuai et al. 2013,Synthesis of Ce3+ doped ZnFe2O4 self-assembled clusters and adsorption of chromium(VI),"A solvothermal synthetic route was used to prepare Ce(3+) doped Zn ferrites, where sphere-like clusters aggregated by nanosized particles were fabricated. The size of the cluster and the saturation magnetization of the sample are decreasing with the increase of Ce(3+). These samples can be easily separated from aqueous solutions by applying a magnetic field and have a high loading capacity of Cr(VI). The Cr(VI) adsorption experiments indicated that the adsorption was divided into two processes, in which the first one took place about 6h, the second one took place between 6 and 96 h. The maximum adsorption capacity for Cr(VI) was determined to be 57.24 mg/g. Langmuir model was employed to fit the adsorption isotherm, which implied the single layer adsorption. The data of SBET, external area and porous area of the samples can be used to explain these adsorption processes. And the Ce(3+) ions doped in the sample induced the increasing adsorption capacity of Cr(VI). The adsorption process can be described by the pseudo-second-order kinetic model.","Synthesis of Ce3+ doped ZnFe2O4 self-assembled clusters and adsorption of chromium(VI) Abs: A solvothermal synthetic route was used to prepare Ce(3+) doped Zn ferrites, where sphere-like clusters aggregated by nanosized particles were fabricated. The size of the cluster and the saturation magnetization of the sample are decreasing with the increase of Ce(3+). These samples can be easily separated from aqueous solutions by applying a magnetic field and have a high loading capacity of Cr(VI). The Cr(VI) adsorption experiments indicated that the adsorption was divided into two processes, in which the first one took place about 6h, the second one took place between 6 and 96 h. The maximum adsorption capacity for Cr(VI) was determined to be 57.24 mg/g. Langmuir model was employed to fit the adsorption isotherm, which implied the single layer adsorption. The data of SBET, external area and porous area of the samples can be used to explain these adsorption processes. And the Ce(3+) ions doped in the sample induced the increasing adsorption capacity of Cr(VI). The adsorption process can be described by the pseudo-second-order kinetic model."
1786217,Krishnani et al. 2013,Hexavalent chromium removal mechanism using conducting polymers,"We report detoxification of Cr(VI) into Cr(III) using electrochemically synthesized polyaniline (PANI), polypyrrole (PPY), PANI nanowires (PANI-NW) and palladium-decorated PANI (PANI-Pd) thin films. Percent Cr(VI) reduction was found to be decreased with an increase in pH from 1.8 to 6.8 and with initial Cr(VI) concentration ranging from 2.5 to 10mg/L. Efficacy of PANI increased at higher temp of 37 °C as compared to 30 °C. PANI-Pd was found to be most effective for all three initial Cr(VI) concentrations at pH 1.8. However, efficacy of PANI-Pd was significantly reduced at higher pHs of 5 and 6.8. Efficacy of PANI and PANI-NW was found to nearly the same. However, there was a significant reduction in effectiveness of PANI-NW at 10mg/L of Cr(VI) at all the three pHs studied, which could be attributed to degradation of PANI-NW by higher initial Cr(VI) concentration. PPY and PANI-NW were found to be highly sensitive with respect to pH and Cr(VI) initial concentration. Chromium speciation on PANI film was carried out by total chromium analysis and XPS, which revealed Cr(III) formation and its subsequent adsorption on the polymer. PANI-Pd and PANI are recommended for future sensor applications for chromium detection at low pH.","Hexavalent chromium removal mechanism using conducting polymers Abs: We report detoxification of Cr(VI) into Cr(III) using electrochemically synthesized polyaniline (PANI), polypyrrole (PPY), PANI nanowires (PANI-NW) and palladium-decorated PANI (PANI-Pd) thin films. Percent Cr(VI) reduction was found to be decreased with an increase in pH from 1.8 to 6.8 and with initial Cr(VI) concentration ranging from 2.5 to 10mg/L. Efficacy of PANI increased at higher temp of 37 °C as compared to 30 °C. PANI-Pd was found to be most effective for all three initial Cr(VI) concentrations at pH 1.8. However, efficacy of PANI-Pd was significantly reduced at higher pHs of 5 and 6.8. Efficacy of PANI and PANI-NW was found to nearly the same. However, there was a significant reduction in effectiveness of PANI-NW at 10mg/L of Cr(VI) at all the three pHs studied, which could be attributed to degradation of PANI-NW by higher initial Cr(VI) concentration. PPY and PANI-NW were found to be highly sensitive with respect to pH and Cr(VI) initial concentration. Chromium speciation on PANI film was carried out by total chromium analysis and XPS, which revealed Cr(III) formation and its subsequent adsorption on the polymer. PANI-Pd and PANI are recommended for future sensor applications for chromium detection at low pH."
1786216,Krim et al. 2013,Protective effect of ginger against toxicity induced by chromate in rats,"The evaluation of the effect of ginger on the modulation of toxic effects induced by chromate is the objective of our study. 50 male rats Albinos Wistar were divided to five groups as follow: group I (T) is served as control, received a mineral water by gavage (per os); group II (G) received an experimental diet with 2% of ginger; group III (Cr) received an oral dose of potassium dichromate (15 mg/kg) and normal diet; group IV (CrG): received an oral dose of potassium dichromate (15 mg/kg) and an experimental diet containing 2% ginger; and group V (Cr(+)G) received an oral dose of potassium dichromate (25 mg/kg) and an experimental diet with 2% of ginger. The results of this study indicate that the chromate provoked a haematoxic effect (anemia), nephrotoxic, hepatotoxic, and also a perturbation in lipids profile. In addition, chromate has a pro-oxidant effect, which was indicated by decrease of reduced glutathione (GSH) levels in different tissues. However, the administration of ginger revealed a reduction of the intensity of oxidative stress induced by the chromate resulting in the decrease of the majority of the previous parameters concentrations. In conclusion we demonstrated that ginger has potent antioxidants activity, revealed by the amelioration of chromate's toxic effects. We can say that ginger has a protective effect towards damages induced by the chromate.","Protective effect of ginger against toxicity induced by chromate in rats Abs: The evaluation of the effect of ginger on the modulation of toxic effects induced by chromate is the objective of our study. 50 male rats Albinos Wistar were divided to five groups as follow: group I (T) is served as control, received a mineral water by gavage (per os); group II (G) received an experimental diet with 2% of ginger; group III (Cr) received an oral dose of potassium dichromate (15 mg/kg) and normal diet; group IV (CrG): received an oral dose of potassium dichromate (15 mg/kg) and an experimental diet containing 2% ginger; and group V (Cr(+)G) received an oral dose of potassium dichromate (25 mg/kg) and an experimental diet with 2% of ginger. The results of this study indicate that the chromate provoked a haematoxic effect (anemia), nephrotoxic, hepatotoxic, and also a perturbation in lipids profile. In addition, chromate has a pro-oxidant effect, which was indicated by decrease of reduced glutathione (GSH) levels in different tissues. However, the administration of ginger revealed a reduction of the intensity of oxidative stress induced by the chromate resulting in the decrease of the majority of the previous parameters concentrations. In conclusion we demonstrated that ginger has potent antioxidants activity, revealed by the amelioration of chromate's toxic effects. We can say that ginger has a protective effect towards damages induced by the chromate."
1786215,Kotyzova et al. ,Effect of chromium (VI) exposure on antioxidant defense status and trace element homeostasis in acute experiment in rat,"Occupational exposure to hexavalent chromium (Cr(VI)) compounds is of concern in many Cr-related industries and their surrounding environment. Cr(VI) is a proven toxin and carcinogen. The Cr(VI) compounds are easily absorbed, can diffuse across cell membranes, and have strong oxidative potential. Despite intensive studies of Cr(VI) pro-oxidative effects, limited data exist on the influence of Cr(VI) on selenoenzymes thioredoxin reductase (TrxR) and glutathione peroxidase (GPx)-important components of antioxidant defense system. This study investigates the effect of Cr(VI) exposure on antioxidant defense status, with focus on these selenoenzymes, and on trace element homeostasis in an acute experiment in rat. Male Wistar rats (130-140g) were assigned to two groups of 8 animals: I. control; and II. Cr(VI) treated. The animals in Cr(VI) group were administered a single dose of K2Cr2O7 (20 mg /kg, intraperitoneally (ip)). The control group received saline solution. After 24 h, the animals were sacrificed and the liver and kidneys were examined for lipid peroxidation (LP; thiobarbituric acid reactive substances (TBARS) concentration), the level of reduced glutathione (GSH) and the activities of GPx-1, TrxR-1, and glutathione reductase (GR). Samples of tissues were also used to estimate Cr accumulation and alterations in zinc, copper, and iron levels. The acute Cr(VI) exposure caused an increase in both hepatic and renal LP (by 70%, p &lt; 0.01 and by 15%, p &lt; 0.05, respectively), increased hepatic GSH level and GPx-1 activity, and decreased renal GPx-1 activity. The activity of GR was not changed. A significant inhibitory effect of Cr(VI) was found on TrxR-1 activity in both the liver and the kidneys. The ability of Cr(VI) to cause TrxR inhibition could contribute to its cytotoxic effects. Further investigation of oxidative responses in different in vivo models may enable the development of strategies to protect against Cr(VI) oxidative damage.","Effect of chromium (VI) exposure on antioxidant defense status and trace element homeostasis in acute experiment in rat Abs: Occupational exposure to hexavalent chromium (Cr(VI)) compounds is of concern in many Cr-related industries and their surrounding environment. Cr(VI) is a proven toxin and carcinogen. The Cr(VI) compounds are easily absorbed, can diffuse across cell membranes, and have strong oxidative potential. Despite intensive studies of Cr(VI) pro-oxidative effects, limited data exist on the influence of Cr(VI) on selenoenzymes thioredoxin reductase (TrxR) and glutathione peroxidase (GPx)-important components of antioxidant defense system. This study investigates the effect of Cr(VI) exposure on antioxidant defense status, with focus on these selenoenzymes, and on trace element homeostasis in an acute experiment in rat. Male Wistar rats (130-140g) were assigned to two groups of 8 animals: I. control; and II. Cr(VI) treated. The animals in Cr(VI) group were administered a single dose of K2Cr2O7 (20 mg /kg, intraperitoneally (ip)). The control group received saline solution. After 24 h, the animals were sacrificed and the liver and kidneys were examined for lipid peroxidation (LP; thiobarbituric acid reactive substances (TBARS) concentration), the level of reduced glutathione (GSH) and the activities of GPx-1, TrxR-1, and glutathione reductase (GR). Samples of tissues were also used to estimate Cr accumulation and alterations in zinc, copper, and iron levels. The acute Cr(VI) exposure caused an increase in both hepatic and renal LP (by 70%, p &lt; 0.01 and by 15%, p &lt; 0.05, respectively), increased hepatic GSH level and GPx-1 activity, and decreased renal GPx-1 activity. The activity of GR was not changed. A significant inhibitory effect of Cr(VI) was found on TrxR-1 activity in both the liver and the kidneys. The ability of Cr(VI) to cause TrxR inhibition could contribute to its cytotoxic effects. Further investigation of oxidative responses in different in vivo models may enable the development of strategies to protect against Cr(VI) oxidative damage."
1786214,Kim et al. 2013,The fine scratches of the spectacle frames and the allergic contact dermatitis,"<strong>BACKGROUND: </strong>Spectacle contact allergy is not infrequent. The fine scratches on the spectacle frames which may play a role in the sensitization to the potential allergenic components have not been studied.<br /><br /><strong>OBJECTIVE: </strong>We sought the relationship between the scratches on the spectacle frames and the allergic contact dermatitis (ACD) in the Republic of Korea.<br /><br /><strong>METHODS: </strong>A total of 42 Korean patients with ACD at the spectacle contact sites were enrolled. Their spectacle frames were examined with the dimethylglyoxime (DMG) test and analyzed by the scanning electron microscopy (SEM) and energy-dispersive X-ray spectroscopy (EDS). Patch tests (thin-layer rapid use epicutaneous test [TRUE tests]) were performed to identify the skin allergens.<br /><br /><strong>RESULTS: </strong>The DMG-positive spectacle frames were identified in 78.5% of the frames. The SEM results showed that there were more scratches on the skin-contacting parts of the spectacle frames than the non-skin-contacting parts of the same frames. In the EDS findings, the mean nickel content (weight, %) of the spectacle frames was 15.7±5.5, and the mean chromium content was 20.3±3.4 at the skin-contacting parts. In the TRUE tests, nickel sulphate was the most common allergen (31 cases, 73.8%), and potassium dichromate was the second (9 cases, 21.4%). Three patients presented simultaneous positive reactions with nickel sulphate and potassium dichromate.<br /><br /><strong>CONCLUSION: </strong>Minor visible and non-visible fine scratches on the spectacle frames may present the provocation factors of the ACD. Nickel sulphate was the most common allergen suspected of provoking the spectacle frame-induced ACD, followed by potassium dichromate.","The fine scratches of the spectacle frames and the allergic contact dermatitis Abs: <strong>BACKGROUND: </strong>Spectacle contact allergy is not infrequent. The fine scratches on the spectacle frames which may play a role in the sensitization to the potential allergenic components have not been studied.<br /><br /><strong>OBJECTIVE: </strong>We sought the relationship between the scratches on the spectacle frames and the allergic contact dermatitis (ACD) in the Republic of Korea.<br /><br /><strong>METHODS: </strong>A total of 42 Korean patients with ACD at the spectacle contact sites were enrolled. Their spectacle frames were examined with the dimethylglyoxime (DMG) test and analyzed by the scanning electron microscopy (SEM) and energy-dispersive X-ray spectroscopy (EDS). Patch tests (thin-layer rapid use epicutaneous test [TRUE tests]) were performed to identify the skin allergens.<br /><br /><strong>RESULTS: </strong>The DMG-positive spectacle frames were identified in 78.5% of the frames. The SEM results showed that there were more scratches on the skin-contacting parts of the spectacle frames than the non-skin-contacting parts of the same frames. In the EDS findings, the mean nickel content (weight, %) of the spectacle frames was 15.7±5.5, and the mean chromium content was 20.3±3.4 at the skin-contacting parts. In the TRUE tests, nickel sulphate was the most common allergen (31 cases, 73.8%), and potassium dichromate was the second (9 cases, 21.4%). Three patients presented simultaneous positive reactions with nickel sulphate and potassium dichromate.<br /><br /><strong>CONCLUSION: </strong>Minor visible and non-visible fine scratches on the spectacle frames may present the provocation factors of the ACD. Nickel sulphate was the most common allergen suspected of provoking the spectacle frame-induced ACD, followed by potassium dichromate."
1786213,Khatami et al. ,Allergic contact dermatitis to metal allergens in Iran,"Background? Metallic allergens such as nickel are among the most common causes of allergic contact dermatitis (ACD), but frequencies of contact dermatitis to these allergens may vary in different areas. Objectives? This study aimed to determine the frequencies of ACD caused by three common metallic allergens: nickel sulfate; potassium dichromate; and cobalt chloride. Methods? Data for 1137 patients with clinical diagnoses of contact dermatitis and/or atopic dermatitis evaluated by patch testing in Iran during a 5-year period were retrospectively studied to establish the frequencies of hypersensitivity to these metallic allergens. Results? A total of 313 patients (27.5%) gave positive patch test results for at least one metallic allergen. Allergy to nickel (229 cases, 20.0%) was the most commonly observed, followed by allergy to cobalt (90 cases, 8.0%) and allergy to chromium (70 cases, 6.2%). Nickel allergy was significantly more frequent in females and in subjects aged &lt;40?years, whereas chromium hypersensitivity was more common in males and in subjects aged &gt;40?years. Sensitivity to nickel or chromium was a risk factor for cobalt allergy. Conclusions? Nickel was most commonly identified as a metallic allergen in Iran and tended to affect women aged &lt;40?years. Regulations pertaining to nickel release may decrease the frequency of nickel hypersensitivity in Iran.","Allergic contact dermatitis to metal allergens in Iran Abs: Background? Metallic allergens such as nickel are among the most common causes of allergic contact dermatitis (ACD), but frequencies of contact dermatitis to these allergens may vary in different areas. Objectives? This study aimed to determine the frequencies of ACD caused by three common metallic allergens: nickel sulfate; potassium dichromate; and cobalt chloride. Methods? Data for 1137 patients with clinical diagnoses of contact dermatitis and/or atopic dermatitis evaluated by patch testing in Iran during a 5-year period were retrospectively studied to establish the frequencies of hypersensitivity to these metallic allergens. Results? A total of 313 patients (27.5%) gave positive patch test results for at least one metallic allergen. Allergy to nickel (229 cases, 20.0%) was the most commonly observed, followed by allergy to cobalt (90 cases, 8.0%) and allergy to chromium (70 cases, 6.2%). Nickel allergy was significantly more frequent in females and in subjects aged &lt;40?years, whereas chromium hypersensitivity was more common in males and in subjects aged &gt;40?years. Sensitivity to nickel or chromium was a risk factor for cobalt allergy. Conclusions? Nickel was most commonly identified as a metallic allergen in Iran and tended to affect women aged &lt;40?years. Regulations pertaining to nickel release may decrease the frequency of nickel hypersensitivity in Iran."
1786212,Kaufman and  Weber 2013,Spectroscopy and photochemistry of sodium chromate ester cluster ions,"In the present study, we investigate the spectroscopy and photochemical behavior of chromate ester cluster ions in vacuo in the visible and near-UV. Chromate ester cluster ions Na(n)[CrO3(OCH3)](n+1)(-) (n = 1, 2) are generated by electrospray ionization of sodium dichromate in water and methanol. Upon irradiation with photon energies between 2 and 5.6 eV, dissociation occurs. The photodissociation spectra of these ions are very similar to the UV/vis absorption spectra of the sample solution with solvatochromic shifts less than 0.1 eV. The electronic excitations in this photon energy range are assigned to ligand-to-metal charge transfer from the oxygen ligands to the chromium within the chromate ester. Fragment channels corresponding to intracluster reactions involving reduction of the metal centers as well as evaporative processes leading to the loss of a neutral Na[CrO3(OCH3)] salt unit are observed. The results are discussed in the framework of organometallic redox mechanisms and density functional theory.","Spectroscopy and photochemistry of sodium chromate ester cluster ions Abs: In the present study, we investigate the spectroscopy and photochemical behavior of chromate ester cluster ions in vacuo in the visible and near-UV. Chromate ester cluster ions Na(n)[CrO3(OCH3)](n+1)(-) (n = 1, 2) are generated by electrospray ionization of sodium dichromate in water and methanol. Upon irradiation with photon energies between 2 and 5.6 eV, dissociation occurs. The photodissociation spectra of these ions are very similar to the UV/vis absorption spectra of the sample solution with solvatochromic shifts less than 0.1 eV. The electronic excitations in this photon energy range are assigned to ligand-to-metal charge transfer from the oxygen ligands to the chromium within the chromate ester. Fragment channels corresponding to intracluster reactions involving reduction of the metal centers as well as evaporative processes leading to the loss of a neutral Na[CrO3(OCH3)] salt unit are observed. The results are discussed in the framework of organometallic redox mechanisms and density functional theory."
1786211,Iranmanesh et al. 2013,Chelation of chromium(VI) by combining deferasirox and deferiprone in rats,"The present research is aimed to characterize the potential efficiency of two chelators after chromium(VI) administration for 60 days following two doses of 15 and 30 mg/kg chromium(VI) per body weight daily to male rats. However, the hypothesis that the two chelators might be more efficient as combined therapy than as single therapy in removing chromium(VI) from rat organs was considered. In this way, two known chelators deferasirox and deferiprone were chosen and given orally as a single or combined therapy for a period of 1 week. Chromium(VI) and iron concentrations in tissues were determined by flame atomic absorption spectroscopy. The combined chelation therapy results show that deferasirox and deferiprone are able to remove chromium(VI) ions from various tissues while iron concentration returned to normal levels and symptoms also decreased.","Chelation of chromium(VI) by combining deferasirox and deferiprone in rats Abs: The present research is aimed to characterize the potential efficiency of two chelators after chromium(VI) administration for 60 days following two doses of 15 and 30 mg/kg chromium(VI) per body weight daily to male rats. However, the hypothesis that the two chelators might be more efficient as combined therapy than as single therapy in removing chromium(VI) from rat organs was considered. In this way, two known chelators deferasirox and deferiprone were chosen and given orally as a single or combined therapy for a period of 1 week. Chromium(VI) and iron concentrations in tissues were determined by flame atomic absorption spectroscopy. The combined chelation therapy results show that deferasirox and deferiprone are able to remove chromium(VI) ions from various tissues while iron concentration returned to normal levels and symptoms also decreased."
1786210,Hennebert et al. 2013,The evaluation of an analytical protocol for the determination of substances in waste for hazard classification,"The classification of waste as hazardous could soon be assessed in Europe using largely the hazard properties of its constituents, according to the the Classification, Labelling and Packaging (CLP) regulation. Comprehensive knowledge of the component constituents of a given waste will therefore be necessary. An analytical protocol for determining waste composition is proposed, which includes using inductively coupled plasma (ICP) screening methods to identify major elements and gas chromatography/mass spectrometry (GC-MS) screening techniques to measure organic compounds. The method includes a gross or indicator measure of 'pools' of higher molecular weight organic substances that are taken to be less bioactive and less hazardous, and of unresolved 'mass' during the chromatography of volatile and semi-volatile compounds. The concentration of some elements and specific compounds that are linked to specific hazard properties and are subject to specific regulation (examples include: heavy metals, chromium(VI), cyanides, organo-halogens, and PCBs) are determined by classical quantitative analysis. To check the consistency of the analysis, the sum of the concentrations (including unresolved 'pools') should give a mass balance between 90% and 110%. Thirty-two laboratory samples comprising different industrial wastes (liquids and solids) were tested by two routine service laboratories, to give circa 7000 parameter results. Despite discrepancies in some parameters, a satisfactory sum of estimated or measured concentrations (analytical balance) of 90% was reached for 20 samples (63% of the overall total) during this first test exercise, with identified reasons for most of the unsatisfactory results. Regular use of this protocol (which is now included in the French legislation) has enabled service laboratories to reach a 90% mass balance for nearly all the solid samples tested, and most of liquid samples (difficulties were caused in some samples from polymers in solution and vegetable oil). The protocol is submitted to French and European normalization bodies (AFNOR and CEN) and further improvements are awaited.","The evaluation of an analytical protocol for the determination of substances in waste for hazard classification Abs: The classification of waste as hazardous could soon be assessed in Europe using largely the hazard properties of its constituents, according to the the Classification, Labelling and Packaging (CLP) regulation. Comprehensive knowledge of the component constituents of a given waste will therefore be necessary. An analytical protocol for determining waste composition is proposed, which includes using inductively coupled plasma (ICP) screening methods to identify major elements and gas chromatography/mass spectrometry (GC-MS) screening techniques to measure organic compounds. The method includes a gross or indicator measure of 'pools' of higher molecular weight organic substances that are taken to be less bioactive and less hazardous, and of unresolved 'mass' during the chromatography of volatile and semi-volatile compounds. The concentration of some elements and specific compounds that are linked to specific hazard properties and are subject to specific regulation (examples include: heavy metals, chromium(VI), cyanides, organo-halogens, and PCBs) are determined by classical quantitative analysis. To check the consistency of the analysis, the sum of the concentrations (including unresolved 'pools') should give a mass balance between 90% and 110%. Thirty-two laboratory samples comprising different industrial wastes (liquids and solids) were tested by two routine service laboratories, to give circa 7000 parameter results. Despite discrepancies in some parameters, a satisfactory sum of estimated or measured concentrations (analytical balance) of 90% was reached for 20 samples (63% of the overall total) during this first test exercise, with identified reasons for most of the unsatisfactory results. Regular use of this protocol (which is now included in the French legislation) has enabled service laboratories to reach a 90% mass balance for nearly all the solid samples tested, and most of liquid samples (difficulties were caused in some samples from polymers in solution and vegetable oil). The protocol is submitted to French and European normalization bodies (AFNOR and CEN) and further improvements are awaited."
1786209,He et al. 2013,Repression of miR-143 Mediates Cr (VI)-Induced Tumor Angiogenesis via IGF-IR/IRS1/ERK/IL-8 Pathway,"Hexavalent chromium [Cr (VI)] is a well-known human carcinogen associated with the increased risk of lung cancer. However, the mechanism underlying the Cr (VI)-induced carcinogenesis remains unclear due to the lack of suitable experimental models. In this study, we developed an in vitro model by transforming nontumorigenic human lung epithelial BEAS-2B cells through long-term exposure to Cr (VI). By utilizing this model, we found that miR-143 expression levels were dramatically repressed in Cr (VI)-transformed cells. The repression of miR-143 led to Cr (VI)-induced cell malignant transformation and angiogenesis via upregulation of insulin-like growth factor-1 receptor (IGF-IR) and insulin receptor substrate-1 (IRS1) expression. Moreover, we found that interleukin-8 is the major upregulated angiogenesis factor induced by Cr (VI) through activation of IGF-IR/IRS1 axis followed by activation of downstream ERK/hypoxia-induced factor-1?/NF-?B signaling pathway. These findings establish a causal role and mechanism of miR-143 in regulating Cr (VI)-induced malignant transformation and tumor angiogenesis.","Repression of miR-143 Mediates Cr (VI)-Induced Tumor Angiogenesis via IGF-IR/IRS1/ERK/IL-8 Pathway Abs: Hexavalent chromium [Cr (VI)] is a well-known human carcinogen associated with the increased risk of lung cancer. However, the mechanism underlying the Cr (VI)-induced carcinogenesis remains unclear due to the lack of suitable experimental models. In this study, we developed an in vitro model by transforming nontumorigenic human lung epithelial BEAS-2B cells through long-term exposure to Cr (VI). By utilizing this model, we found that miR-143 expression levels were dramatically repressed in Cr (VI)-transformed cells. The repression of miR-143 led to Cr (VI)-induced cell malignant transformation and angiogenesis via upregulation of insulin-like growth factor-1 receptor (IGF-IR) and insulin receptor substrate-1 (IRS1) expression. Moreover, we found that interleukin-8 is the major upregulated angiogenesis factor induced by Cr (VI) through activation of IGF-IR/IRS1 axis followed by activation of downstream ERK/hypoxia-induced factor-1?/NF-?B signaling pathway. These findings establish a causal role and mechanism of miR-143 in regulating Cr (VI)-induced malignant transformation and tumor angiogenesis."
1786208,Hassanin et al. 2013,The prospective protective effect of selenium nanoparticles against chromium-induced oxidative and cellular damage in rat thyroid,"<strong>BACKGROUND: </strong>Nanotechnology has enabled researchers to synthesize nanosize particles that possess increased surface areas. Compared to conventional microparticles, it has resulted in increased interactions with biological targets.<br /><br /><strong>OBJECTIVE: </strong>The objective of this study was to determine the protective ability of selenium nanoparticles against hexavalent chromium-induced thyrotoxicity.<br /><br /><strong>DESIGN: </strong>Twenty male rats were used in the study, and arbitrarily assigned to four groups. Group 1 was the control group, and was given phosphate-buffered saline. Group 2 was the chromium-treated group and was given K2Cr2O7 60 ?g/kg body weight intraperitoneally as a single dose on the third day of administration. Group 3 was the nano-selenium-treated group and was given selenium nanoparticles (size 3-20 nm) 0.5 mg/kg body weight intraperitoneally daily for 5 consecutive days. Group 4 was the nano-selenium chromium-treated group, which received selenium nanoparticles for 5 days and a single dose of K2Cr2O7 on the third day of administration.<br /><br /><strong>MATERIALS AND METHODS: </strong>Blood samples were collected from rats for measuring thyroid hormones (free triiodothyronine [T3] and free thyroxine [T4]) and oxidative and antioxidant parameters (malondialdehyde [MDA], reduced glutathione [GSH], catalase, and superoxide dismutase [SOD]). Upon dissection, thyroid glands were taken for histopathological examination by using paraffin preparations stained with hematoxylin and eosin (H&amp;E) and Masson's trichrome. Immunohistochemical staining was performed for detecting cellular proliferation using Ki67 antibodies.<br /><br /><strong>RESULTS: </strong>The present study shows that K2Cr2O7 has a toxic effect on the thyroid gland as a result of inducing a marked oxidative damage and release of reactive oxygen species. This was shown by the significant decrease in free T3 and T4 and GSH levels, which was accompanied by significant increases in catalase, SOD, and MDA in the chromium-treated group compared to the control group. Se nanoparticles have a protective effect on K2Cr2O7-induced thyroid damage, as a result of correcting the free T3 and T4 levels and GSH, catalase, SOD, and MDA compared to the K2Cr2O7-treated group. Administration of nano-selenium alone in the nano-selenium-treated group had no toxic effect on rats' thyroid compared to the control group. The biochemical results were confirmed by histopathological, immunohistochemical and pathomorphological studies.","The prospective protective effect of selenium nanoparticles against chromium-induced oxidative and cellular damage in rat thyroid Abs: <strong>BACKGROUND: </strong>Nanotechnology has enabled researchers to synthesize nanosize particles that possess increased surface areas. Compared to conventional microparticles, it has resulted in increased interactions with biological targets.<br /><br /><strong>OBJECTIVE: </strong>The objective of this study was to determine the protective ability of selenium nanoparticles against hexavalent chromium-induced thyrotoxicity.<br /><br /><strong>DESIGN: </strong>Twenty male rats were used in the study, and arbitrarily assigned to four groups. Group 1 was the control group, and was given phosphate-buffered saline. Group 2 was the chromium-treated group and was given K2Cr2O7 60 ?g/kg body weight intraperitoneally as a single dose on the third day of administration. Group 3 was the nano-selenium-treated group and was given selenium nanoparticles (size 3-20 nm) 0.5 mg/kg body weight intraperitoneally daily for 5 consecutive days. Group 4 was the nano-selenium chromium-treated group, which received selenium nanoparticles for 5 days and a single dose of K2Cr2O7 on the third day of administration.<br /><br /><strong>MATERIALS AND METHODS: </strong>Blood samples were collected from rats for measuring thyroid hormones (free triiodothyronine [T3] and free thyroxine [T4]) and oxidative and antioxidant parameters (malondialdehyde [MDA], reduced glutathione [GSH], catalase, and superoxide dismutase [SOD]). Upon dissection, thyroid glands were taken for histopathological examination by using paraffin preparations stained with hematoxylin and eosin (H&amp;E) and Masson's trichrome. Immunohistochemical staining was performed for detecting cellular proliferation using Ki67 antibodies.<br /><br /><strong>RESULTS: </strong>The present study shows that K2Cr2O7 has a toxic effect on the thyroid gland as a result of inducing a marked oxidative damage and release of reactive oxygen species. This was shown by the significant decrease in free T3 and T4 and GSH levels, which was accompanied by significant increases in catalase, SOD, and MDA in the chromium-treated group compared to the control group. Se nanoparticles have a protective effect on K2Cr2O7-induced thyroid damage, as a result of correcting the free T3 and T4 levels and GSH, catalase, SOD, and MDA compared to the K2Cr2O7-treated group. Administration of nano-selenium alone in the nano-selenium-treated group had no toxic effect on rats' thyroid compared to the control group. The biochemical results were confirmed by histopathological, immunohistochemical and pathomorphological studies."
1786207,Hassan et al. 2013,Effect of organics and alkalinity on the sulfur oxidizing bacteria (SOB) biosensor,"The environmental risk assessment of toxic chemicals in stream water requires the use of a low cost standardized toxicity bioassay. Here, a biosensor for detection of toxic chemicals in stream water was studied using sulfur oxidizing bacteria (SOB) in continuous mode. The biosensor depends on the ability of SOB to oxidize sulfur particles under aerobic conditions to produce sulfuric acid. The reaction results in an increase in electrical conductivity (EC) and a decrease in pH. The biosensor is based on the inhibition of SOB in the presence of toxic chemicals by measuring changes in EC and pH. We found that the SOB biosensor can detect Cr(6+)at a low concentration (50 ppb) which is lower than many whole-cell biosensors. The effect of organic material in real stream water on SOB activity was studied. Due to the presence of mixotrophic SOB, we found that the presence of organic matter increases SOB activity which decreases the biosensor start up period. Low alkalinity (22 mg L(-1) CaCO(3)) increased effluent EC and decreased effluent pH which is optimal for biosensor operation. While at high alkalinity (820 mg L(-1) CaCO(3), the activity of SOB little decreased. We found that system can detect 50 ppb of Cr(6+) at low alkalinity (22 mg L(-1) CaCO(3)) in few hours while, complete inhibition was observed after 35 h of operation at high alkalinity (820 mg L(-1) CaCO(3)).","Effect of organics and alkalinity on the sulfur oxidizing bacteria (SOB) biosensor Abs: The environmental risk assessment of toxic chemicals in stream water requires the use of a low cost standardized toxicity bioassay. Here, a biosensor for detection of toxic chemicals in stream water was studied using sulfur oxidizing bacteria (SOB) in continuous mode. The biosensor depends on the ability of SOB to oxidize sulfur particles under aerobic conditions to produce sulfuric acid. The reaction results in an increase in electrical conductivity (EC) and a decrease in pH. The biosensor is based on the inhibition of SOB in the presence of toxic chemicals by measuring changes in EC and pH. We found that the SOB biosensor can detect Cr(6+)at a low concentration (50 ppb) which is lower than many whole-cell biosensors. The effect of organic material in real stream water on SOB activity was studied. Due to the presence of mixotrophic SOB, we found that the presence of organic matter increases SOB activity which decreases the biosensor start up period. Low alkalinity (22 mg L(-1) CaCO(3)) increased effluent EC and decreased effluent pH which is optimal for biosensor operation. While at high alkalinity (820 mg L(-1) CaCO(3), the activity of SOB little decreased. We found that system can detect 50 ppb of Cr(6+) at low alkalinity (22 mg L(-1) CaCO(3)) in few hours while, complete inhibition was observed after 35 h of operation at high alkalinity (820 mg L(-1) CaCO(3))."
1786206,Hassan et al. 2013,Kinetics and mechanism of oxidation of chondroitin-4-sulfate polysaccharide by chromic acid in aqueous perchlorate solutions,"The kinetics of chromic acid oxidation of chondroitin-4-sulfate polysaccharide as sulfated carbohydrates at a constant ionic strength of 4.0 mol dm(-3) has been investigated, spectrophotometrically. The reaction kinetics showed a first-order dependence in chromic acid and fractional-first-order kinetics with respect to the chondroitin-4-sulfate concentration. The influence of [H(+)] on the reaction rates showed that the oxidation process is acid-catalyzed. Added Mn(2+) ions indicated the formation of Cr(IV) as intermediate species. A kinetic evidence for formation of 1:1 intermediate complex was revealed. The kinetic parameters have been evaluated and a tentative reaction mechanism in good consistent with the kinetic results obtained is discussed.","Kinetics and mechanism of oxidation of chondroitin-4-sulfate polysaccharide by chromic acid in aqueous perchlorate solutions Abs: The kinetics of chromic acid oxidation of chondroitin-4-sulfate polysaccharide as sulfated carbohydrates at a constant ionic strength of 4.0 mol dm(-3) has been investigated, spectrophotometrically. The reaction kinetics showed a first-order dependence in chromic acid and fractional-first-order kinetics with respect to the chondroitin-4-sulfate concentration. The influence of [H(+)] on the reaction rates showed that the oxidation process is acid-catalyzed. Added Mn(2+) ions indicated the formation of Cr(IV) as intermediate species. A kinetic evidence for formation of 1:1 intermediate complex was revealed. The kinetic parameters have been evaluated and a tentative reaction mechanism in good consistent with the kinetic results obtained is discussed."
1786205,Gupta et al. 2013,Removal of Cr(VI) onto Ficus carica biosorbent from water,"The utilization of sustainable and biodegradable lignocellulosic fiber to detoxify the noxious Cr(VI) from wastewater is considered a versatile approach to clean up a contaminated aquatic environment. The aim of the present research is to assess the proficiency and mechanism of biosorption on Ficus carica bast fiber via isotherm models (Langmuir, Freundlich, Temkin, Harkin's-Jura, and Dubinin-Radushkevich), kinetic models, and thermodynamic parameters. The biomass extracted from fig plant was characterized by scanning electron microscopy and Fourier-transform infrared spectroscopy. To optimize the maximum removal efficiency, different parameters like effect of initial concentration, effect of temperature, pH, and contact time were studied by batch method. The equilibrium data were best represented by the Langmuir isotherm model, and the maximum adsorption capacity of Cr(VI) onto biosorbent was found to be 19.68 mg/g. The pseudo-second-order kinetic model adequately described the kinetic data. The calculated values of thermodynamic parameters such as enthalpy change (?H(0)), entropy change (?S(0)), and free energy change (?G(0)) were 21.55 kJ/mol, 76.24 J/mol K, and -1.55 kJ/mol, respectively, at 30 °C which accounted for spontaneous and endothermic processes. The study of adsorbent capacity for Cr(VI) removal in the presence of Na(+), Mg(2+), Ca(2+), SO 4 (2-) , HCO 3 (-) and Cl(-) illustrated that the removal of Cr(VI) increased in the presence of HCO(3-) ions; the presence of Na(+), SO 4 (2-) or Cl(-) showed no significant influence on Cr(VI) adsorption, while Ca(2+) and Mg(2+) ions led to an insignificant decrease in Cr(VI) adsorption. Further, the desorption studies illustrated that 31.10% of metal ions can be removed from an aqueous system, out of which 26.63% of metal ions can be recovered by desorption in first cycle and the adsorbent can be reused. The results of the scale-up study show that the ecofriendly detoxification of Cr(VI) from aqueous systems was technologically feasible.","Removal of Cr(VI) onto Ficus carica biosorbent from water Abs: The utilization of sustainable and biodegradable lignocellulosic fiber to detoxify the noxious Cr(VI) from wastewater is considered a versatile approach to clean up a contaminated aquatic environment. The aim of the present research is to assess the proficiency and mechanism of biosorption on Ficus carica bast fiber via isotherm models (Langmuir, Freundlich, Temkin, Harkin's-Jura, and Dubinin-Radushkevich), kinetic models, and thermodynamic parameters. The biomass extracted from fig plant was characterized by scanning electron microscopy and Fourier-transform infrared spectroscopy. To optimize the maximum removal efficiency, different parameters like effect of initial concentration, effect of temperature, pH, and contact time were studied by batch method. The equilibrium data were best represented by the Langmuir isotherm model, and the maximum adsorption capacity of Cr(VI) onto biosorbent was found to be 19.68 mg/g. The pseudo-second-order kinetic model adequately described the kinetic data. The calculated values of thermodynamic parameters such as enthalpy change (?H(0)), entropy change (?S(0)), and free energy change (?G(0)) were 21.55 kJ/mol, 76.24 J/mol K, and -1.55 kJ/mol, respectively, at 30 °C which accounted for spontaneous and endothermic processes. The study of adsorbent capacity for Cr(VI) removal in the presence of Na(+), Mg(2+), Ca(2+), SO 4 (2-) , HCO 3 (-) and Cl(-) illustrated that the removal of Cr(VI) increased in the presence of HCO(3-) ions; the presence of Na(+), SO 4 (2-) or Cl(-) showed no significant influence on Cr(VI) adsorption, while Ca(2+) and Mg(2+) ions led to an insignificant decrease in Cr(VI) adsorption. Further, the desorption studies illustrated that 31.10% of metal ions can be removed from an aqueous system, out of which 26.63% of metal ions can be recovered by desorption in first cycle and the adsorbent can be reused. The results of the scale-up study show that the ecofriendly detoxification of Cr(VI) from aqueous systems was technologically feasible."
1786204,Gupta et al. 2013,Synechococcus elongatus PCC 7942 is more tolerant to chromate as compared to Synechocystis sp. PCC 6803,"Two unicellular cyanobacteria Synechocystis sp. PCC 6803 and Synechococcus elongatus PCC 7942 showed contrasting responses to chromate stress with EC50 of 12 ± 2 and 150 ± 15 ?M potassium dichromate respectively. There was no depletion of chromate in growth medium in both the cases. Using labeled chromate, very low accumulation (&lt;1 nmol/10(8) cells) was observed in Synechocystis after incubation for 24 h in light. No accumulation of chromate could be observed in Synechococcus under these conditions. Chromate oxyanion is known to enter the cells using sulfate uptake channels. Therefore, inhibition of sulfate uptake caused by chromate was monitored using (35)S labeled sulfate. IC50 values of chromate for (35)sulfate uptake were higher in Synechococcus as compared to Synechocystis. The results suggested that the sulfate transporters in Synechococcus have lower affinity to chromate than those from Synechocystis possibly due to differences in affinity of sulfate receptors for chromate. Bioinformatic analyses revealed presence of sulfate and chromate transporters with considerable similarity; however, minor differences in these may play a role in their differential response to chromate. In both cases the IC50 values decreased when sulfate concentration was reduced in the medium indicating competitive inhibition of sulfate uptake by chromate. Interestingly, Synechococcus showed stimulation of growth at concentrations of chromate less than 100 ?M, which affected its cell size without disturbing the ultrastructure and thylakoid organization. In Synechocystis, growth with 12 ?M potassium dichromate damaged the ultrastructure and thylakoid organization with slight elongation of the cells. The results suggested that Synechococcus possesses efficient strategies to prevent entry and to remove chromate from the cell as compared to Synechocystis. This is the first time a differential response of Synechococcus 7942 and Synechocystis 6803 to chromate is reported. The contrasting characteristics observed in the two cyanobacteria will be useful in understanding the basis of resistance or susceptibility to chromate.","Synechococcus elongatus PCC 7942 is more tolerant to chromate as compared to Synechocystis sp. PCC 6803 Abs: Two unicellular cyanobacteria Synechocystis sp. PCC 6803 and Synechococcus elongatus PCC 7942 showed contrasting responses to chromate stress with EC50 of 12 ± 2 and 150 ± 15 ?M potassium dichromate respectively. There was no depletion of chromate in growth medium in both the cases. Using labeled chromate, very low accumulation (&lt;1 nmol/10(8) cells) was observed in Synechocystis after incubation for 24 h in light. No accumulation of chromate could be observed in Synechococcus under these conditions. Chromate oxyanion is known to enter the cells using sulfate uptake channels. Therefore, inhibition of sulfate uptake caused by chromate was monitored using (35)S labeled sulfate. IC50 values of chromate for (35)sulfate uptake were higher in Synechococcus as compared to Synechocystis. The results suggested that the sulfate transporters in Synechococcus have lower affinity to chromate than those from Synechocystis possibly due to differences in affinity of sulfate receptors for chromate. Bioinformatic analyses revealed presence of sulfate and chromate transporters with considerable similarity; however, minor differences in these may play a role in their differential response to chromate. In both cases the IC50 values decreased when sulfate concentration was reduced in the medium indicating competitive inhibition of sulfate uptake by chromate. Interestingly, Synechococcus showed stimulation of growth at concentrations of chromate less than 100 ?M, which affected its cell size without disturbing the ultrastructure and thylakoid organization. In Synechocystis, growth with 12 ?M potassium dichromate damaged the ultrastructure and thylakoid organization with slight elongation of the cells. The results suggested that Synechococcus possesses efficient strategies to prevent entry and to remove chromate from the cell as compared to Synechocystis. This is the first time a differential response of Synechococcus 7942 and Synechocystis 6803 to chromate is reported. The contrasting characteristics observed in the two cyanobacteria will be useful in understanding the basis of resistance or susceptibility to chromate."
1786203,Guo et al. 2013,Hexavalent chromium-induced alteration of proteomic landscape in human skin fibroblast cells,"Hexavalent chromium [Cr(VI)] generated during industrial processes is carcinogenic. Although much is known about the deleterious effects caused by reactive oxygen species generated during the reduction of Cr(VI) after its absorption by biological systems, the precise mechanisms underlying Cr(VI) cytotoxicity remain poorly defined. Here, we analyzed, at the global proteome scale, the perturbation of protein expression in GM00637 human skin fibroblast cells upon exposure to potassium dichromate (K2Cr2O7). We were able to quantify ?4600 unique proteins, among which ?400 exhibited significant alterations in expression levels upon a 24-h treatment with 0.5 ?M K2Cr2O7. Pathway analysis revealed the Cr(VI)-induced perturbation of cholesterol biosynthesis, G-protein signaling, inflammatory response, and selenoprotein pathways. In particular, we discovered that the K2Cr2O7 treatment led to pronouncedly elevated expression of a large number of enzymes involved in de novo cholesterol biosynthesis. Real-time PCR analysis revealed the increased mRNA expression of selected genes involved in cholesterol biosynthesis. Consistently, K2Cr2O7 treatment resulted in marked increases in cellular cholesterol level in multiple cell lines. Moreover, the Cr(VI)-induced growth inhibition of cultured human cells could be rescued by a cholesterol-lowering drug, lovastatin. Together, we demonstrated, for the first time, that Cr(VI) may exert its cytotoxic effect, at least partly, through the up-regulation of enzymes involved in de novo cholesterol biosynthesis and the resultant increase of cholesterol level in cells.","Hexavalent chromium-induced alteration of proteomic landscape in human skin fibroblast cells Abs: Hexavalent chromium [Cr(VI)] generated during industrial processes is carcinogenic. Although much is known about the deleterious effects caused by reactive oxygen species generated during the reduction of Cr(VI) after its absorption by biological systems, the precise mechanisms underlying Cr(VI) cytotoxicity remain poorly defined. Here, we analyzed, at the global proteome scale, the perturbation of protein expression in GM00637 human skin fibroblast cells upon exposure to potassium dichromate (K2Cr2O7). We were able to quantify ?4600 unique proteins, among which ?400 exhibited significant alterations in expression levels upon a 24-h treatment with 0.5 ?M K2Cr2O7. Pathway analysis revealed the Cr(VI)-induced perturbation of cholesterol biosynthesis, G-protein signaling, inflammatory response, and selenoprotein pathways. In particular, we discovered that the K2Cr2O7 treatment led to pronouncedly elevated expression of a large number of enzymes involved in de novo cholesterol biosynthesis. Real-time PCR analysis revealed the increased mRNA expression of selected genes involved in cholesterol biosynthesis. Consistently, K2Cr2O7 treatment resulted in marked increases in cellular cholesterol level in multiple cell lines. Moreover, the Cr(VI)-induced growth inhibition of cultured human cells could be rescued by a cholesterol-lowering drug, lovastatin. Together, we demonstrated, for the first time, that Cr(VI) may exert its cytotoxic effect, at least partly, through the up-regulation of enzymes involved in de novo cholesterol biosynthesis and the resultant increase of cholesterol level in cells."
1786202,Güner et al. ,The triggering role of allergic contact dermatitis in discoid lupus erythematosus,"Abstract Background: The onset and exacerbations of discoid lupus erythematosus (DLE) can be precipitated by several factors like needling, scratches, trauma, X-rays, heat, cold, pressure, tattooing, scars, allergic and irritant dermatitis and inflammatory dermatoses. Objective: To investigate the role of allergic contact dermatitis (ACD) in devolopment and triggering of the lesions of DLE. Materials and methods: This study was performed on 30 patients with DLE. European baseline series and cosmetic patch test series were used. At least 1+ reaction was accepted as meaningful. Results: Twenty-three (76.7%) of 30 DLE patients and 16 (40%) of 40 control group patients were allergic to at least one allergen on standard patch test series. The difference between the groups were found statistically significant. Seventeen (56.7%) of 30 DLE patients and 6 (15%) of 40 control group patients were allergic to at least one allergen on cosmetic patch test series. The difference between the groups were statistically significant. The most sensitized allergens in both the groups were nickel sulphate, paraphenylen diamine, potassium dichromate from standard patch test series; quaternium 15, cocamidopropyl betain from cosmetic patch test series, in order. Conclusion: This study is distinctive since it is the first study to determine the eliciting role of ACD on DLE by imposing standard and cosmetic patch test series on DLE and control group patients. Worldwide, there is no study based on this subject. In the DLE group, the results of sensitization on standard and cosmetic patch test series were higher and statistically significant. Larger studies are required to reveal the exact role.","The triggering role of allergic contact dermatitis in discoid lupus erythematosus Abs: Abstract Background: The onset and exacerbations of discoid lupus erythematosus (DLE) can be precipitated by several factors like needling, scratches, trauma, X-rays, heat, cold, pressure, tattooing, scars, allergic and irritant dermatitis and inflammatory dermatoses. Objective: To investigate the role of allergic contact dermatitis (ACD) in devolopment and triggering of the lesions of DLE. Materials and methods: This study was performed on 30 patients with DLE. European baseline series and cosmetic patch test series were used. At least 1+ reaction was accepted as meaningful. Results: Twenty-three (76.7%) of 30 DLE patients and 16 (40%) of 40 control group patients were allergic to at least one allergen on standard patch test series. The difference between the groups were found statistically significant. Seventeen (56.7%) of 30 DLE patients and 6 (15%) of 40 control group patients were allergic to at least one allergen on cosmetic patch test series. The difference between the groups were statistically significant. The most sensitized allergens in both the groups were nickel sulphate, paraphenylen diamine, potassium dichromate from standard patch test series; quaternium 15, cocamidopropyl betain from cosmetic patch test series, in order. Conclusion: This study is distinctive since it is the first study to determine the eliciting role of ACD on DLE by imposing standard and cosmetic patch test series on DLE and control group patients. Worldwide, there is no study based on this subject. In the DLE group, the results of sensitization on standard and cosmetic patch test series were higher and statistically significant. Larger studies are required to reveal the exact role."
1786201,Gunasundari and  Muthukumar 2013,Simultaneous Cr(VI) reduction and phenol degradation using Stenotrophomonas sp. isolated from tannery effluent contaminated soil,"This study presents simultaneous hexavalent chromium (Cr(VI)) reduction and phenol degradation using Stenotrophomonas sp., isolated from tannery effluent contaminated soil. Phenol was used as the sole carbon and energy source for Cr(VI) reduction. The optimization of different operating parameters was done using Placket-Burman design (PBD) and Box-Behnken design (BBD). The significant operating variables identified by PBD were initial Cr(VI) and phenol concentration, pH, temperature, and reaction time. These variables were optimized by a three-level BBD and the optimum initial Cr(VI) concentration, initial phenol concentration, pH, temperature, and reaction time obtained were 16.59 mg/l, 200.05 mg/l, 7.38, 31.96 °C and 4.07 days, respectively. Under the optimum conditions, 81.27 % Cr(VI) reduction and 100 % phenol degradation were observed experimentally. The results concluded that the Stenotrophomonas sp. could be used to decontaminate the effluents containing Cr(VI) and phenol effectively.","Simultaneous Cr(VI) reduction and phenol degradation using Stenotrophomonas sp. isolated from tannery effluent contaminated soil Abs: This study presents simultaneous hexavalent chromium (Cr(VI)) reduction and phenol degradation using Stenotrophomonas sp., isolated from tannery effluent contaminated soil. Phenol was used as the sole carbon and energy source for Cr(VI) reduction. The optimization of different operating parameters was done using Placket-Burman design (PBD) and Box-Behnken design (BBD). The significant operating variables identified by PBD were initial Cr(VI) and phenol concentration, pH, temperature, and reaction time. These variables were optimized by a three-level BBD and the optimum initial Cr(VI) concentration, initial phenol concentration, pH, temperature, and reaction time obtained were 16.59 mg/l, 200.05 mg/l, 7.38, 31.96 °C and 4.07 days, respectively. Under the optimum conditions, 81.27 % Cr(VI) reduction and 100 % phenol degradation were observed experimentally. The results concluded that the Stenotrophomonas sp. could be used to decontaminate the effluents containing Cr(VI) and phenol effectively."
1786200,Ghosh et al. 2013,Suitable combination of promoter and micellar catalyst for kilo fold rate acceleration on benzaldehyde to benzoic acid conversion in aqueous media at room temperature: a kinetic approach,"The kinetics of oxidation of benzaldehyde by chromic acid in aqueous and aqueous surfactant (sodium dodecyl sulfate, SDS, alkyl phenyl polyethylene glycol, Triton X-100 and N-cetylpyridinium chloride, CPC) media have been investigated in the presence of promoter at 303 K. The pseudo-first-order rate constants (kobs) were determined from a logarithmic plot of absorbance as a function time. The rate constants were found to increase with introduction of heteroaromatic nitrogen base promoters such as Picolinic acid (PA), 2,2'-bipyridine (bipy) and 1,10-phenanthroline (phen). The product benzoic acid has been characterized by conventional melting point experiment, NMR, HRMS and FTIR spectral analysis. The mechanism of both unpromoted and promoted reaction path has been proposed for the reaction. In presence of the anionic surfactant SDS, cationic surfactant CPC and neutral surfactant TX-100 the reaction can undergo simultaneously in both aqueous and micellar phase with an enhanced rate of oxidation in the micellar phase. Both SDS and TX-100 produce normal micellar effect whereas CPC produce reverse micellar effect in the presence of benzaldehyde. The observed net enhancement of rate effects has been explained by considering the hydrophobic and electrostatic interaction between the surfactants and reactants. SDS and bipy combination is the suitable one for benzaldehyde oxidation.","Suitable combination of promoter and micellar catalyst for kilo fold rate acceleration on benzaldehyde to benzoic acid conversion in aqueous media at room temperature: a kinetic approach Abs: The kinetics of oxidation of benzaldehyde by chromic acid in aqueous and aqueous surfactant (sodium dodecyl sulfate, SDS, alkyl phenyl polyethylene glycol, Triton X-100 and N-cetylpyridinium chloride, CPC) media have been investigated in the presence of promoter at 303 K. The pseudo-first-order rate constants (kobs) were determined from a logarithmic plot of absorbance as a function time. The rate constants were found to increase with introduction of heteroaromatic nitrogen base promoters such as Picolinic acid (PA), 2,2'-bipyridine (bipy) and 1,10-phenanthroline (phen). The product benzoic acid has been characterized by conventional melting point experiment, NMR, HRMS and FTIR spectral analysis. The mechanism of both unpromoted and promoted reaction path has been proposed for the reaction. In presence of the anionic surfactant SDS, cationic surfactant CPC and neutral surfactant TX-100 the reaction can undergo simultaneously in both aqueous and micellar phase with an enhanced rate of oxidation in the micellar phase. Both SDS and TX-100 produce normal micellar effect whereas CPC produce reverse micellar effect in the presence of benzaldehyde. The observed net enhancement of rate effects has been explained by considering the hydrophobic and electrostatic interaction between the surfactants and reactants. SDS and bipy combination is the suitable one for benzaldehyde oxidation."
1786199,Garg et al. 2013,"Pentachlorophenol dechlorination and simultaneous Cr6+ reduction by Pseudomonas putida SKG-1 MTCC (10510): characterization of PCP dechlorination products, bacterial structure, and functional groups","It is the first report in which a novel psychrotrophic Pseudomonas putida SKG-1 strain was evaluated for simultaneous bioremediation of pentachlorophenol and Cr(6+) under various cultural and nutritional conditions. Pentachlorophenol (PCP) dechlorination products, bacterial structure, and functional groups were characterized by gas chromatography and mass spectrometry (GC-MS), scanning electron microscope and energy dispersive X-ray spectroscopy (SEM-EDS), and Fourier-transform infrared (FTIR) techniques. The strain was extremely tolerant to excessively higher individual concentration of PCP (1,400 mg l(-1)) and Cr(6+) (4,300 mg l(-1)). Increasing concentration of PCP and Cr(6+) exerted inhibitory effect on bacterial growth and toxicants' removal. The strain exhibited growth, and concomitantly remediated both the pollutants simultaneously over a broad pH (7.0-9.0) and temperature (28-32 °C) range; maximum growth, PCP dechlorination (87.5%), and Cr(6+) removal (80.0%) occurred at optimum pH 8.0 and 30 °C (from initial PCP 100 mg l(-1) and Cr(6+) 500 mg l(-1)) under shaking (150 rpm) within 72 h incubation. Optimization of agitation (125 rpm) and aeration (0.4 vvm) in bioreactor further enhanced PCP dechlorination by ~10% and Cr(6+) removal by 2%. A direct correlation existed between growth and bioremediation of both the toxicants. Among other heavy metals, mercury exerted maximum and cobalt minimum inhibitory effect on PCP dechlorination and Cr(6+) removal. Chromate reductase activity was mainly associated with the supernatant and cytosolic fraction of bacterial cells. GC-MS analysis revealed the formation of tetrachloro-p-hydroquinone, 2,4,6-trichlorophenol, and 2,6-dichlorophenol as PCP dechlorination products. FTIR spectrometry indicated likely involvement of carbonyl and amide groups in Cr(3+) adsorption, and SEM-EDS showed the presence of chromium on P. putida surface. Thus, our promising isolate can be ecofriendly employed for biotreatment of various industrial wastes contaminated with high PCP and Cr(6+) concentrations.","Pentachlorophenol dechlorination and simultaneous Cr6+ reduction by Pseudomonas putida SKG-1 MTCC (10510): characterization of PCP dechlorination products, bacterial structure, and functional groups Abs: It is the first report in which a novel psychrotrophic Pseudomonas putida SKG-1 strain was evaluated for simultaneous bioremediation of pentachlorophenol and Cr(6+) under various cultural and nutritional conditions. Pentachlorophenol (PCP) dechlorination products, bacterial structure, and functional groups were characterized by gas chromatography and mass spectrometry (GC-MS), scanning electron microscope and energy dispersive X-ray spectroscopy (SEM-EDS), and Fourier-transform infrared (FTIR) techniques. The strain was extremely tolerant to excessively higher individual concentration of PCP (1,400 mg l(-1)) and Cr(6+) (4,300 mg l(-1)). Increasing concentration of PCP and Cr(6+) exerted inhibitory effect on bacterial growth and toxicants' removal. The strain exhibited growth, and concomitantly remediated both the pollutants simultaneously over a broad pH (7.0-9.0) and temperature (28-32 °C) range; maximum growth, PCP dechlorination (87.5%), and Cr(6+) removal (80.0%) occurred at optimum pH 8.0 and 30 °C (from initial PCP 100 mg l(-1) and Cr(6+) 500 mg l(-1)) under shaking (150 rpm) within 72 h incubation. Optimization of agitation (125 rpm) and aeration (0.4 vvm) in bioreactor further enhanced PCP dechlorination by ~10% and Cr(6+) removal by 2%. A direct correlation existed between growth and bioremediation of both the toxicants. Among other heavy metals, mercury exerted maximum and cobalt minimum inhibitory effect on PCP dechlorination and Cr(6+) removal. Chromate reductase activity was mainly associated with the supernatant and cytosolic fraction of bacterial cells. GC-MS analysis revealed the formation of tetrachloro-p-hydroquinone, 2,4,6-trichlorophenol, and 2,6-dichlorophenol as PCP dechlorination products. FTIR spectrometry indicated likely involvement of carbonyl and amide groups in Cr(3+) adsorption, and SEM-EDS showed the presence of chromium on P. putida surface. Thus, our promising isolate can be ecofriendly employed for biotreatment of various industrial wastes contaminated with high PCP and Cr(6+) concentrations."
1786198,Frederick et al. 2013,Chromate reduction is expedited by bacteria engineered to produce the compatible solute trehalose,"The toxicity and solubility of chromium(VI) can be decreased by certain microbes that reduce chromium(VI) to chromium(III). However, these bacteria do not escape unscathed from this process. Chromium(VI) reduction damages the essential macromolecules of living systems. Trehalose protects organisms from chemical stress but has not been tested in the context of bioremediation. We engineered bacteria to produce trehalose and found that they then reduced 1 mM chromium(VI) to chromium(III), whereas wild-type cells were only able to reduce half that amount. Thus, by providing bacteria with a biochemical defense against the side-effects of chromate reduction may be a new approach to cleaning up sites that are contaminated with high levels of chromate.","Chromate reduction is expedited by bacteria engineered to produce the compatible solute trehalose Abs: The toxicity and solubility of chromium(VI) can be decreased by certain microbes that reduce chromium(VI) to chromium(III). However, these bacteria do not escape unscathed from this process. Chromium(VI) reduction damages the essential macromolecules of living systems. Trehalose protects organisms from chemical stress but has not been tested in the context of bioremediation. We engineered bacteria to produce trehalose and found that they then reduced 1 mM chromium(VI) to chromium(III), whereas wild-type cells were only able to reduce half that amount. Thus, by providing bacteria with a biochemical defense against the side-effects of chromate reduction may be a new approach to cleaning up sites that are contaminated with high levels of chromate."
1786197,Ding et al. 2013,Epithelial-mesenchymal transition during oncogenic transformation induced by hexavalent chromium involves reactive oxygen species-dependent mechanism in lung epithelial cells,"Hexavalent chromium [Cr(VI)] is an important human carcinogen associated with pulmonary diseases and lung cancer. Exposure to Cr(VI) induces DNA damage, cell morphological change and malignant transformation in human lung epithelial cells. Despite extensive studies, the molecular mechanisms remain elusive, it is also not known if Cr(VI)-induced transformation might accompany with invasive properties to facilitate metastasis. We aimed to study Cr(VI)-induced epithelial-mesenchymal transition (EMT) and invasion during oncogenic transformation in lung epithelial cells. The results showed that Cr(VI) at low doses represses E-cadherin mRNA and protein expression, enhances mesenchymal marker vimentin expression and transforms the epithelial cell into fibroblastoid morphology. Cr(VI) also increases cell invasion and promotes colony formation. Further studies indicated that Cr(VI) uses multiple mechanisms to repress E-cadherin expression, including activation of E-cadherin repressors such as Slug, ZEB1, KLF8 and enhancement the binding of HDAC1 in E-cadherin gene promoter, but DNA methylation is not responsible for the loss of E-cadherin. Catalase reduces Cr(VI)-induced E-cadherin and vimentin protein expression, attenuates cell invasion in matrigel and colony formation on soft agar. These results demonstrate that exposure to a common human carcinogen, Cr(VI), induces EMT and invasion during oncogenic transformation in lung epithelial cells and implicate in cancer metastasis and prevention.","Epithelial-mesenchymal transition during oncogenic transformation induced by hexavalent chromium involves reactive oxygen species-dependent mechanism in lung epithelial cells Abs: Hexavalent chromium [Cr(VI)] is an important human carcinogen associated with pulmonary diseases and lung cancer. Exposure to Cr(VI) induces DNA damage, cell morphological change and malignant transformation in human lung epithelial cells. Despite extensive studies, the molecular mechanisms remain elusive, it is also not known if Cr(VI)-induced transformation might accompany with invasive properties to facilitate metastasis. We aimed to study Cr(VI)-induced epithelial-mesenchymal transition (EMT) and invasion during oncogenic transformation in lung epithelial cells. The results showed that Cr(VI) at low doses represses E-cadherin mRNA and protein expression, enhances mesenchymal marker vimentin expression and transforms the epithelial cell into fibroblastoid morphology. Cr(VI) also increases cell invasion and promotes colony formation. Further studies indicated that Cr(VI) uses multiple mechanisms to repress E-cadherin expression, including activation of E-cadherin repressors such as Slug, ZEB1, KLF8 and enhancement the binding of HDAC1 in E-cadherin gene promoter, but DNA methylation is not responsible for the loss of E-cadherin. Catalase reduces Cr(VI)-induced E-cadherin and vimentin protein expression, attenuates cell invasion in matrigel and colony formation on soft agar. These results demonstrate that exposure to a common human carcinogen, Cr(VI), induces EMT and invasion during oncogenic transformation in lung epithelial cells and implicate in cancer metastasis and prevention."
1786196,Dhal et al. 2013,Chemical and microbial remediation of hexavalent chromium from contaminated soil and mining/metallurgical solid waste: a review,"Chromium is a highly toxic non-essential metal for microorganisms and plants, and its occurrence is rare in nature. Lower to higher chromium containing effluents and solid wastes released by activities such as mining, metal plating, wood preservation, ink manufacture, dyes, pigments, glass and ceramics, tanning and textile industries, and corrosion inhibitors in cooling water, induce pollution and may cause major health hazards. Besides, natural processes (weathering and biochemical) also contribute to the mobility of chromium which enters in to the soil affecting the plant growth and metabolic functions of the living species. Generally, chemical processes are used for Cr- remediation. However, with the inference derived from the diverse Cr-resistance mechanism displayed by microorganisms and the plants including biosorption, diminished accumulation, precipitation, reduction of Cr(VI) to Cr(III), and chromate efflux, bioremediation is emerging as a potential tool to address the problem of Cr(VI) pollution. This review focuses on the chemistry of chromium, its use, and toxicity and mobility in soil, while assessing its concentration in effluents/wastes which becomes the source of pollution. In order to conserve the environment and resources, the chemical/biological remediation processes for Cr(VI) and their efficiency have been summarised in some detail. The interaction of chromium with various microbial/bacterial strains isolated and their reduction capacity towards Cr(VI) are also discussed.","Chemical and microbial remediation of hexavalent chromium from contaminated soil and mining/metallurgical solid waste: a review Abs: Chromium is a highly toxic non-essential metal for microorganisms and plants, and its occurrence is rare in nature. Lower to higher chromium containing effluents and solid wastes released by activities such as mining, metal plating, wood preservation, ink manufacture, dyes, pigments, glass and ceramics, tanning and textile industries, and corrosion inhibitors in cooling water, induce pollution and may cause major health hazards. Besides, natural processes (weathering and biochemical) also contribute to the mobility of chromium which enters in to the soil affecting the plant growth and metabolic functions of the living species. Generally, chemical processes are used for Cr- remediation. However, with the inference derived from the diverse Cr-resistance mechanism displayed by microorganisms and the plants including biosorption, diminished accumulation, precipitation, reduction of Cr(VI) to Cr(III), and chromate efflux, bioremediation is emerging as a potential tool to address the problem of Cr(VI) pollution. This review focuses on the chemistry of chromium, its use, and toxicity and mobility in soil, while assessing its concentration in effluents/wastes which becomes the source of pollution. In order to conserve the environment and resources, the chemical/biological remediation processes for Cr(VI) and their efficiency have been summarised in some detail. The interaction of chromium with various microbial/bacterial strains isolated and their reduction capacity towards Cr(VI) are also discussed."
1786195,Dhal et al. ,Characterizing toxic Cr(VI) contamination in chromite mine overburden dump and its bacterial remediation,"Cr(VI) generated due to natural oxidation of chromite mineral present in chromite mine overburden (COB) dumps of Sukinda, India, has been characterized by different physico-chemical methods. The Cr(VI) was found to be associated with goethite matrix at a contamination level of 500mgCr(VI)kg(-1) of COB. Bacillus sp. isolated from the overburden sample exhibiting high tolerance to the hexavalent chromium, was used for the remediation of Cr(VI) in the overburden. The process was optimized while varying the parameters such as pH (2-9), pulp density (10-60%) and temperature (25-40°C). Optimal reduction of more than 98% of Cr(VI) in the COB sample was achieved in 16h at pH~7.0 and 60% pulp density with the Bacillus sp. (4.05×10(7)cellsmL(-1)) in absence of media. The exponential rate equation yielded rate constant value of 2.14×10(-1)h(-1) at 60% pulp density. The mode of bio-reduction of Cr(VI) in the overburden sample was established by FT-IR, XRD, EPMA and SEM-EDS studies.","Characterizing toxic Cr(VI) contamination in chromite mine overburden dump and its bacterial remediation Abs: Cr(VI) generated due to natural oxidation of chromite mineral present in chromite mine overburden (COB) dumps of Sukinda, India, has been characterized by different physico-chemical methods. The Cr(VI) was found to be associated with goethite matrix at a contamination level of 500mgCr(VI)kg(-1) of COB. Bacillus sp. isolated from the overburden sample exhibiting high tolerance to the hexavalent chromium, was used for the remediation of Cr(VI) in the overburden. The process was optimized while varying the parameters such as pH (2-9), pulp density (10-60%) and temperature (25-40°C). Optimal reduction of more than 98% of Cr(VI) in the COB sample was achieved in 16h at pH~7.0 and 60% pulp density with the Bacillus sp. (4.05×10(7)cellsmL(-1)) in absence of media. The exponential rate equation yielded rate constant value of 2.14×10(-1)h(-1) at 60% pulp density. The mode of bio-reduction of Cr(VI) in the overburden sample was established by FT-IR, XRD, EPMA and SEM-EDS studies."
1786194,Darakas et al. 2013,Hexavalent chromium release from lignite fly ash and related ecotoxic effects,"Hexavalent chromium Cr(VI) is a pollutant of immense concern due to its high mobility to water sources and highly toxic properties. In most cases, Cr(VI) could be released from lignite fly ash in aquatic environment when fly ash comes into contact with water. In this study, the contribution of the leaching patterns and bioavailability of Cr(VI) from lignite fly ash to the overall ecotoxic properties of fly ash leachates was originally examined and leaching procedures were evaluated in this context. A series of customized leaching tests were conducted and a battery of ecotoxicity tests including the crustacean Daphnia magna and the photobacterium Vibrio fischeri was applied. The leaching of Cr(VI) was pH and liquid to solid (L/S) ratio dependent, exhibiting the highest releases at pH values between 7 and 8. At the liquid to solid ratio (L/S) equal to 100 L/kg, the (CrVI) release reached a plateau, implying the presence of diffusion constrains and/or solubility hindrances. The toxic effect of the leachates obtained under leaching at pH 7 towards D. magna was relatively high (TU = 28.6 (23.8-35.7) at L/S = 10 L/kg). Interestingly, the toxicity of the leachates towards D. magna not only was significantly correlated to Cr(VI) (r = 0.961, P &lt; 0.01), but the toxicity of the leachates (in absolute values) was matching the toxicity of the Cr(VI) revealing its remarkable contribution to the overall effect. In addition, the lower sensitivity of the bacteria V. fischeri when exposed to the leachates, along with the time dependence of the toxicity profiles supported the interpretation of the results obtained in this study.","Hexavalent chromium release from lignite fly ash and related ecotoxic effects Abs: Hexavalent chromium Cr(VI) is a pollutant of immense concern due to its high mobility to water sources and highly toxic properties. In most cases, Cr(VI) could be released from lignite fly ash in aquatic environment when fly ash comes into contact with water. In this study, the contribution of the leaching patterns and bioavailability of Cr(VI) from lignite fly ash to the overall ecotoxic properties of fly ash leachates was originally examined and leaching procedures were evaluated in this context. A series of customized leaching tests were conducted and a battery of ecotoxicity tests including the crustacean Daphnia magna and the photobacterium Vibrio fischeri was applied. The leaching of Cr(VI) was pH and liquid to solid (L/S) ratio dependent, exhibiting the highest releases at pH values between 7 and 8. At the liquid to solid ratio (L/S) equal to 100 L/kg, the (CrVI) release reached a plateau, implying the presence of diffusion constrains and/or solubility hindrances. The toxic effect of the leachates obtained under leaching at pH 7 towards D. magna was relatively high (TU = 28.6 (23.8-35.7) at L/S = 10 L/kg). Interestingly, the toxicity of the leachates towards D. magna not only was significantly correlated to Cr(VI) (r = 0.961, P &lt; 0.01), but the toxicity of the leachates (in absolute values) was matching the toxicity of the Cr(VI) revealing its remarkable contribution to the overall effect. In addition, the lower sensitivity of the bacteria V. fischeri when exposed to the leachates, along with the time dependence of the toxicity profiles supported the interpretation of the results obtained in this study."
1786193,Choppala et al. ,Concomitant reduction and immobilization of chromium in relation to its bioavailability in soils,"In this study, two carbon materials [chicken manure biochar (CMB) and black carbon (BC)] were investigated for their effects on the reduction of hexavalent chromium [Cr(VI)] in two spiked [600 mg Cr(VI) kg(-1)] and one tannery waste contaminated [454 mg Cr(VI)?kg(-1)] soils. In spiked soils, both the rate and the maximum extent of reduction of Cr(VI) to trivalent Cr [Cr(III)] were higher in the sandy loam than clay soil, which is attributed to the difference in the extent of Cr(VI) adsorption between the soils. The highest rate of Cr(VI) reduction was observed in BC-amended sandy loam soil, where it reduced 452 mg kg(-1) of Cr(VI), followed by clay soil (427 mg kg(-1)) and tannery soil (345 mg kg(-1)). X-ray photoelectron microscopy confirmed the presence of both Cr(VI) and Cr(III) species in BC within 24 h of addition of Cr(VI), which proved its high reduction capacity. The resultant Cr(III) species either adsorbs or precipitates in BC and CMB. The addition of carbon materials to the tannery soil was also effective in decreasing the phytotoxicity of Cr(VI) in mustard (Brassica juncea L.) plants. Therefore, it is concluded that the addition of carbon materials enhanced the reduction of Cr(VI) and the subsequent immobilization of Cr(III) in soils.","Concomitant reduction and immobilization of chromium in relation to its bioavailability in soils Abs: In this study, two carbon materials [chicken manure biochar (CMB) and black carbon (BC)] were investigated for their effects on the reduction of hexavalent chromium [Cr(VI)] in two spiked [600 mg Cr(VI) kg(-1)] and one tannery waste contaminated [454 mg Cr(VI)?kg(-1)] soils. In spiked soils, both the rate and the maximum extent of reduction of Cr(VI) to trivalent Cr [Cr(III)] were higher in the sandy loam than clay soil, which is attributed to the difference in the extent of Cr(VI) adsorption between the soils. The highest rate of Cr(VI) reduction was observed in BC-amended sandy loam soil, where it reduced 452 mg kg(-1) of Cr(VI), followed by clay soil (427 mg kg(-1)) and tannery soil (345 mg kg(-1)). X-ray photoelectron microscopy confirmed the presence of both Cr(VI) and Cr(III) species in BC within 24 h of addition of Cr(VI), which proved its high reduction capacity. The resultant Cr(III) species either adsorbs or precipitates in BC and CMB. The addition of carbon materials to the tannery soil was also effective in decreasing the phytotoxicity of Cr(VI) in mustard (Brassica juncea L.) plants. Therefore, it is concluded that the addition of carbon materials enhanced the reduction of Cr(VI) and the subsequent immobilization of Cr(III) in soils."
1786192,Chatham-Stephens et al. 2013,"Burden of disease from toxic waste sites in India, indonesia, and the Philippines in 2010","Background: Prior calculations of the burden of disease from toxic exposures have not included estimates of the burden from toxic waste sites due to the absence of exposure data.Objective: We developed a disability-adjusted life year (DALY)-based estimate of the disease burden attributable to toxic waste sites. We focused on three low- and middle-income countries (LMICs): India, Indonesia, and the Philippines.Methods: Sites were identified through the Blacksmith Institute's Toxic Sites Identification Program, a global effort to identify waste sites in LMICs. At least one of eight toxic chemicals was sampled in environmental media at each site, and the population at risk estimated. By combining estimates of disease incidence from these exposures with population data, we calculated the DALYs attributable to exposures at each site.Results: We estimated that in 2010, 8,629,750 persons were at risk of exposure to industrial pollutants at 373 toxic waste sites in the three countries, and that these exposures resulted in 828,722 DALYs, with a range of 814,934-1,557,121 DALYs, depending on the weighting factor used. This disease burden is comparable to estimated burdens for outdoor air pollution (1,448,612 DALYs) and malaria (725,000 DALYs) in these countries. Lead and hexavalent chromium collectively accounted for 99.2% of the total DALYs for the chemicals evaluated.Conclusions: Toxic waste sites are responsible for a significant burden of disease in LMICs. Although some factors, such as unidentified and unscreened sites, may cause our estimate to be an underestimate of the actual burden of disease, other factors, such as extrapolation of environmental sampling to the entire exposed population, may result in an overestimate of the burden of disease attributable to these sites. Toxic waste sites are a major, and heretofore underrecognized, global health problem.","Burden of disease from toxic waste sites in India, indonesia, and the Philippines in 2010 Abs: Background: Prior calculations of the burden of disease from toxic exposures have not included estimates of the burden from toxic waste sites due to the absence of exposure data.Objective: We developed a disability-adjusted life year (DALY)-based estimate of the disease burden attributable to toxic waste sites. We focused on three low- and middle-income countries (LMICs): India, Indonesia, and the Philippines.Methods: Sites were identified through the Blacksmith Institute's Toxic Sites Identification Program, a global effort to identify waste sites in LMICs. At least one of eight toxic chemicals was sampled in environmental media at each site, and the population at risk estimated. By combining estimates of disease incidence from these exposures with population data, we calculated the DALYs attributable to exposures at each site.Results: We estimated that in 2010, 8,629,750 persons were at risk of exposure to industrial pollutants at 373 toxic waste sites in the three countries, and that these exposures resulted in 828,722 DALYs, with a range of 814,934-1,557,121 DALYs, depending on the weighting factor used. This disease burden is comparable to estimated burdens for outdoor air pollution (1,448,612 DALYs) and malaria (725,000 DALYs) in these countries. Lead and hexavalent chromium collectively accounted for 99.2% of the total DALYs for the chemicals evaluated.Conclusions: Toxic waste sites are responsible for a significant burden of disease in LMICs. Although some factors, such as unidentified and unscreened sites, may cause our estimate to be an underestimate of the actual burden of disease, other factors, such as extrapolation of environmental sampling to the entire exposed population, may result in an overestimate of the burden of disease attributable to these sites. Toxic waste sites are a major, and heretofore underrecognized, global health problem."
1786191,Cao et al. 2013,Removal of chromium (VI) from electroplating wastewater using an anion exchanger derived from rice straw,"An anion exchanger from rice straw was used to remove Cr (VI) from synthetic wastewater and electroplating effluent. The exchanger was characterized using Fourier transform infrared (FTIR) spectrum and scanning electron microscopy (SEM), and it was found that the quaternary amino group and hydroxyl group are the main functional groups on the fibrous surface of the exchanger. The effect of contact time, initial concentration and pH on the removal of Cr (VI), and adsorption isotherms at different temperature, was investigated. The results showed that the removal of Cr (VI) was very rapid and was significantly affected by the initial pH of the solution. Although acidic conditions (pH = 2-6) facilitated Cr (VI) adsorption, the exchanger was effective in neutral solution and even under weak base conditions. The equilibrium data fitted well with Langmuir adsorption model, and the maximum Cr (VI) adsorption capacities at pH 6.4 were 0.35, 0.36 and 0.38 mmol/g for 15, 25 and 35 degrees C, respectively. The exchanger was finally tested with real electroplating wastewater, and at sorbent dosage of 10 g/L, the removal efficiencies for Cr (VI) and total Cr were 99.4% and 97.8%, respectively. In addition, the positive relationship between adsorbed Cr (VI) and desorbed Cl- suggested that Cr (VI) was mainly removed by ion exchange with chlorine.","Removal of chromium (VI) from electroplating wastewater using an anion exchanger derived from rice straw Abs: An anion exchanger from rice straw was used to remove Cr (VI) from synthetic wastewater and electroplating effluent. The exchanger was characterized using Fourier transform infrared (FTIR) spectrum and scanning electron microscopy (SEM), and it was found that the quaternary amino group and hydroxyl group are the main functional groups on the fibrous surface of the exchanger. The effect of contact time, initial concentration and pH on the removal of Cr (VI), and adsorption isotherms at different temperature, was investigated. The results showed that the removal of Cr (VI) was very rapid and was significantly affected by the initial pH of the solution. Although acidic conditions (pH = 2-6) facilitated Cr (VI) adsorption, the exchanger was effective in neutral solution and even under weak base conditions. The equilibrium data fitted well with Langmuir adsorption model, and the maximum Cr (VI) adsorption capacities at pH 6.4 were 0.35, 0.36 and 0.38 mmol/g for 15, 25 and 35 degrees C, respectively. The exchanger was finally tested with real electroplating wastewater, and at sorbent dosage of 10 g/L, the removal efficiencies for Cr (VI) and total Cr were 99.4% and 97.8%, respectively. In addition, the positive relationship between adsorbed Cr (VI) and desorbed Cl- suggested that Cr (VI) was mainly removed by ion exchange with chlorine."
1786190,Brocato and  Costa 2013,Basic mechanics of DNA methylation and the unique landscape of the DNA methylome in metal-induced carcinogenesis,"Abstract DNA methylation plays an intricate role in the regulation of gene expression and events that compromise the integrity of the methylome may potentially contribute to disease development. DNA methylation is a reversible and regulatory modification that elicits a cascade of events leading to chromatin condensation and gene silencing. In general, normal cells are characterized by gene-specific hypomethylation and global hypermethylation, while cancer cells portray a reverse profile to this norm. The unique methylome displayed in cancer cells is induced after exposure to carcinogenic metals such as nickel, arsenic, cadmium, and chromium (VI). These metals alter the DNA methylation profile by provoking both hyper- and hypo-methylation events. The metal-stimulated deviations to the methylome are possible mechanisms for metal-induced carcinogenesis and may provide potential biomarkers for cancer detection. Development of therapies based on the cancer methylome requires further research including human studies that supply results with larger impact and higher human relevance.","Basic mechanics of DNA methylation and the unique landscape of the DNA methylome in metal-induced carcinogenesis Abs: Abstract DNA methylation plays an intricate role in the regulation of gene expression and events that compromise the integrity of the methylome may potentially contribute to disease development. DNA methylation is a reversible and regulatory modification that elicits a cascade of events leading to chromatin condensation and gene silencing. In general, normal cells are characterized by gene-specific hypomethylation and global hypermethylation, while cancer cells portray a reverse profile to this norm. The unique methylome displayed in cancer cells is induced after exposure to carcinogenic metals such as nickel, arsenic, cadmium, and chromium (VI). These metals alter the DNA methylation profile by provoking both hyper- and hypo-methylation events. The metal-stimulated deviations to the methylome are possible mechanisms for metal-induced carcinogenesis and may provide potential biomarkers for cancer detection. Development of therapies based on the cancer methylome requires further research including human studies that supply results with larger impact and higher human relevance."
1786189,Bhattacharya et al. 2013,Potential of biosorbent developed from fruit peel of Trewia nudiflora for removal of hexavalent chromium from synthetic and industrial effluent: Analyzing phytotoxicity in germinating Vigna seeds,"Chromium (VI) removal efficiency of a biosorbent prepared from fruit peel of Trewia nudiflora plant was studied. The effect of pH, sorbent dose, initial metal concentration and temperature was studied with synthetic Cr?? solution in batch mode. About 278 mg/g of Cr?? sorption was obtained at 293 K at an optimum pH of 2.0 and biosorbent dose of 0.75 g/L. Equilibrium sorption data with varying initial concentration of Cr?? (22-248 mg/L) at three different temperatures (293-313 K) were analyzed by various isotherms. Biosorption kinetics and thermodynamics were described using standard model equations. Encouraging results were obtained by the application of the biosorptive treatment for removal of Cr?? from wastewater collected from common effluent treatment plant of tannery industry. In addition, C??r desorption behavior was studied on different systems. Biosorbent was characterized by FESEM, FT-IR and XRD, etc. Effect of the biosorptive treatement with respect to the phytotoxicity of Cr?? was analyzed by studying the seed germination behavior and enzyme activity of a pulse seed (Vigna radiata L.). Different concentrations of Cr?? solution in both synthetic medium, as well as, in tannery effluent was employed and the results were compared with that of biosorbent treated medium. The study showed that due to efficient removal of Cr?? from aqueous phase, considerable enhancement of seed germination, as well as, increase in root length was obtained for the biosorbent treated solutions which were close to that of the control values. Significant decrease (P &lt; 0.01) in POD activity was observed in seeds irrigated with biosorbent treated wastewater compared to untreated wastewater. The study showed that the novel biosorbent prepared might be utilized for abatement of heavy metal toxicity, i.e., Cr?? from industrial effluent.","Potential of biosorbent developed from fruit peel of Trewia nudiflora for removal of hexavalent chromium from synthetic and industrial effluent: Analyzing phytotoxicity in germinating Vigna seeds Abs: Chromium (VI) removal efficiency of a biosorbent prepared from fruit peel of Trewia nudiflora plant was studied. The effect of pH, sorbent dose, initial metal concentration and temperature was studied with synthetic Cr?? solution in batch mode. About 278 mg/g of Cr?? sorption was obtained at 293 K at an optimum pH of 2.0 and biosorbent dose of 0.75 g/L. Equilibrium sorption data with varying initial concentration of Cr?? (22-248 mg/L) at three different temperatures (293-313 K) were analyzed by various isotherms. Biosorption kinetics and thermodynamics were described using standard model equations. Encouraging results were obtained by the application of the biosorptive treatment for removal of Cr?? from wastewater collected from common effluent treatment plant of tannery industry. In addition, C??r desorption behavior was studied on different systems. Biosorbent was characterized by FESEM, FT-IR and XRD, etc. Effect of the biosorptive treatement with respect to the phytotoxicity of Cr?? was analyzed by studying the seed germination behavior and enzyme activity of a pulse seed (Vigna radiata L.). Different concentrations of Cr?? solution in both synthetic medium, as well as, in tannery effluent was employed and the results were compared with that of biosorbent treated medium. The study showed that due to efficient removal of Cr?? from aqueous phase, considerable enhancement of seed germination, as well as, increase in root length was obtained for the biosorbent treated solutions which were close to that of the control values. Significant decrease (P &lt; 0.01) in POD activity was observed in seeds irrigated with biosorbent treated wastewater compared to untreated wastewater. The study showed that the novel biosorbent prepared might be utilized for abatement of heavy metal toxicity, i.e., Cr?? from industrial effluent."
1786188,Arora et al. 2013,Estimation of blood alcohol concentration in deaths due to roadside accidents,"Like any other disease, accidents too are caused by interaction between agent, host, and environment. Human factors include age, (accidents most common between 10 and 24 years), sex, education, medical conditions (heart attack, impaired vision), fatigue, influence of alcohol and other drugs, lack of bodily protection (like helmets, seat belts) and psychosocial factors like lack of experience, impulsiveness, aggressiveness, defective judgment and delay in decisions. Drunken driving is an important risk factor in causing accidents. This study was focused on the status of alcohol consumption in relation with roadside accidents in northern India in the region of Amritsar. The present study was carried out in 100 cases alleged to have died of roadside accident and brought to the mortuary attached to the Department of Forensic Medicine and Toxicology, Government Medical College, Amritsar for autopsy examination. Blood samples were collected from the femoral vein and were tested for the presence of alcohol with steam distillation and titration method using potassium dichromate and sulfuric acid. In the present study, 23% of the fatal driver/pedestrian victims of roadside accidents were found to have consumed alcohol before accident. Most of the victims of road accident were from the age group 21-30 and 31-40 years. Most of the accidents occurred on straight roads instead of bends or intersections, more during daytime and weekends. 57% of the blood alcohol positives were between 100 mg% and 149 mg%. Majority of the victims of roadside accidents were motorcyclists and the striking vehicles were trucks and buses causing head &amp; neck injuries in most of the victims. Death occurred within a few minutes in most of the cases.","Estimation of blood alcohol concentration in deaths due to roadside accidents Abs: Like any other disease, accidents too are caused by interaction between agent, host, and environment. Human factors include age, (accidents most common between 10 and 24 years), sex, education, medical conditions (heart attack, impaired vision), fatigue, influence of alcohol and other drugs, lack of bodily protection (like helmets, seat belts) and psychosocial factors like lack of experience, impulsiveness, aggressiveness, defective judgment and delay in decisions. Drunken driving is an important risk factor in causing accidents. This study was focused on the status of alcohol consumption in relation with roadside accidents in northern India in the region of Amritsar. The present study was carried out in 100 cases alleged to have died of roadside accident and brought to the mortuary attached to the Department of Forensic Medicine and Toxicology, Government Medical College, Amritsar for autopsy examination. Blood samples were collected from the femoral vein and were tested for the presence of alcohol with steam distillation and titration method using potassium dichromate and sulfuric acid. In the present study, 23% of the fatal driver/pedestrian victims of roadside accidents were found to have consumed alcohol before accident. Most of the victims of road accident were from the age group 21-30 and 31-40 years. Most of the accidents occurred on straight roads instead of bends or intersections, more during daytime and weekends. 57% of the blood alcohol positives were between 100 mg% and 149 mg%. Majority of the victims of roadside accidents were motorcyclists and the striking vehicles were trucks and buses causing head &amp; neck injuries in most of the victims. Death occurred within a few minutes in most of the cases."
1786187,Ahmed et al. 2013,"Chromium (VI) induced acute toxicity and genotoxicity in freshwater stinging catfish, Heteropneustes fossilis","Acute toxicity and genotoxicity of Chromium(VI) as K2Cr2O7 were evaluated in freshwater stinging catfish, Heteropneustes fossilis. Fish showed behavioral alterations after K2Cr2O7 exposure and 96h-LC50 was 35.724mg/L in semi-static bioassay. Fish were exposed to three sub-lethal concentrations (concentration I=1/4th of 96h-LC50, concentration II=1/10th of 96h-LC50 and concentration III=environmental concentration of Cr reported in the river Buriganga). Blood, liver and gill samples were collected after 48h, 96h and 192h. Micronucleus (MN) assay was conducted in blood erythrocytes and DNA damage was evaluated by comet assay in whole blood, gill and liver tissues. Cr(VI) significantly (p&lt;0.05) induced MN frequency and tail DNA (percent) which increased in a concentration depended manner in all types of tissues. Frequency of MN and tail DNA (percent) increased after 48 and 96h of exposure which decreased after 192h of exposure. The liver was the most sensitive to chromium (VI) exposure among the tissues with highest tail DNA (33.70±0.68 percent) at 9.0mg/L after 96h. This study found MN and comet assays in combination as an adequate approach for ecotoxicological monitoring and Cr(VI) as potential genotoxic agent.","Chromium (VI) induced acute toxicity and genotoxicity in freshwater stinging catfish, Heteropneustes fossilis Abs: Acute toxicity and genotoxicity of Chromium(VI) as K2Cr2O7 were evaluated in freshwater stinging catfish, Heteropneustes fossilis. Fish showed behavioral alterations after K2Cr2O7 exposure and 96h-LC50 was 35.724mg/L in semi-static bioassay. Fish were exposed to three sub-lethal concentrations (concentration I=1/4th of 96h-LC50, concentration II=1/10th of 96h-LC50 and concentration III=environmental concentration of Cr reported in the river Buriganga). Blood, liver and gill samples were collected after 48h, 96h and 192h. Micronucleus (MN) assay was conducted in blood erythrocytes and DNA damage was evaluated by comet assay in whole blood, gill and liver tissues. Cr(VI) significantly (p&lt;0.05) induced MN frequency and tail DNA (percent) which increased in a concentration depended manner in all types of tissues. Frequency of MN and tail DNA (percent) increased after 48 and 96h of exposure which decreased after 192h of exposure. The liver was the most sensitive to chromium (VI) exposure among the tissues with highest tail DNA (33.70±0.68 percent) at 9.0mg/L after 96h. This study found MN and comet assays in combination as an adequate approach for ecotoxicological monitoring and Cr(VI) as potential genotoxic agent."
1786186,Afolaranmi and  Grant 2013,The effect of ascorbic acid on the distribution of soluble Cr and Co ions in the blood and organs of rats,"Metal ions (Cr and Co) are released from metal orthopaedic implants in situ. We investigated tissue dissemination of Cr III, Cr VI and Co II ions in the body, and determined if administration of ascorbic acid (AA) affected their in vivo distribution using rats as a model system. Organs of rats treated with both Cr (VI) and Co (II) have higher metal ion levels when compared with control levels in the organs of rats without metal treatment. The reduced form of chromium, Cr III, is reported to be relatively impermeant to cell membranes in vitro, and in line with this, Cr III did not distribute into the organs of the rats after administration in vivo. Potent in vitro reduction of Cr (VI) to Cr III by AA was observed in this study. Prior intraperitoneal injection of AA lowered tissue uptake of both Cr VI and Co II, and increased faecal excretion, but not to a significant extent. AA may only be effective in increasing elimination of Cr VI at high concentrations when plasma reduction is saturated, and may be of limited therapeutic use in patients with orthopaedic implants.","The effect of ascorbic acid on the distribution of soluble Cr and Co ions in the blood and organs of rats Abs: Metal ions (Cr and Co) are released from metal orthopaedic implants in situ. We investigated tissue dissemination of Cr III, Cr VI and Co II ions in the body, and determined if administration of ascorbic acid (AA) affected their in vivo distribution using rats as a model system. Organs of rats treated with both Cr (VI) and Co (II) have higher metal ion levels when compared with control levels in the organs of rats without metal treatment. The reduced form of chromium, Cr III, is reported to be relatively impermeant to cell membranes in vitro, and in line with this, Cr III did not distribute into the organs of the rats after administration in vivo. Potent in vitro reduction of Cr (VI) to Cr III by AA was observed in this study. Prior intraperitoneal injection of AA lowered tissue uptake of both Cr VI and Co II, and increased faecal excretion, but not to a significant extent. AA may only be effective in increasing elimination of Cr VI at high concentrations when plasma reduction is saturated, and may be of limited therapeutic use in patients with orthopaedic implants."
1776328,Brown 2010,Maintenance Center Albany Puts the Hex on Hexavalent Chromium: Safer Substitute Found for Anodizing Aluminum Parts,Journal article.,Maintenance Center Albany Puts the Hex on Hexavalent Chromium: Safer Substitute Found for Anodizing Aluminum Parts Abs: Journal article.
1760237,Wu et al. 2013,Fabrication of the micro/nano-structure superhydrophobic surface on aluminum alloy by sulfuric acid anodizing and polypropylene coating,"The preparation of the superhydrophobic surface on aluminum alloy by anodizing and polypropylene (PP) coating was reported. Both the different anodizing process and different PP coatings of aluminum alloy were investigated. The effects of different anodizing conditions, such as electrolyte concentration, anodization time and current on the superhydrophobic surface were discussed. By PP coating after anodizing, a good superhydrophobic surface was facilely fabricated. The optimum conditions for anodizing were determined by orthogonal experiments. After the aluminium-alloy was grinded with 600# sandpaper, pretreated by 73 g/L hydrochloric acid solution at 1 min, when the concentration of sulfuric acid was 180 g/L, the concentration of oxalic acid was 5 g/L, the concentration of potassium dichromate was 10 g/L, the concentration of chloride sodium was 50 g/L and 63 g/L of glycerol, anodization time was 20 min, and anodization current was 1.2 A/dm2, anodization temperature was 30-35 degrees C, the best micro-nanostructure aluminum alloy films was obtained. On the other hand, the PP with different concentrations was used to the PP with different concentrations was used to coat the aluminum alloy surface after anodizing. The results showed that the best superhydrophobicity was achieved by coating PP, and the duration of the superhydrophobic surface was improved by modifying the coat the aluminum alloy surface after anodizing. The results showed that the best superhydrophobicity was surface with high concentration PP. The morphologies of micro/nano-structure superhydrophobic surface were further confirmed by scanning electron microscope (SEM). The material of PP with the low surface free energy combined with the micro/nano-structures of the surface resulted in the superhydrophobicity of the aluminum alloy surface.","Fabrication of the micro/nano-structure superhydrophobic surface on aluminum alloy by sulfuric acid anodizing and polypropylene coating Abs: The preparation of the superhydrophobic surface on aluminum alloy by anodizing and polypropylene (PP) coating was reported. Both the different anodizing process and different PP coatings of aluminum alloy were investigated. The effects of different anodizing conditions, such as electrolyte concentration, anodization time and current on the superhydrophobic surface were discussed. By PP coating after anodizing, a good superhydrophobic surface was facilely fabricated. The optimum conditions for anodizing were determined by orthogonal experiments. After the aluminium-alloy was grinded with 600# sandpaper, pretreated by 73 g/L hydrochloric acid solution at 1 min, when the concentration of sulfuric acid was 180 g/L, the concentration of oxalic acid was 5 g/L, the concentration of potassium dichromate was 10 g/L, the concentration of chloride sodium was 50 g/L and 63 g/L of glycerol, anodization time was 20 min, and anodization current was 1.2 A/dm2, anodization temperature was 30-35 degrees C, the best micro-nanostructure aluminum alloy films was obtained. On the other hand, the PP with different concentrations was used to the PP with different concentrations was used to coat the aluminum alloy surface after anodizing. The results showed that the best superhydrophobicity was achieved by coating PP, and the duration of the superhydrophobic surface was improved by modifying the coat the aluminum alloy surface after anodizing. The results showed that the best superhydrophobicity was surface with high concentration PP. The morphologies of micro/nano-structure superhydrophobic surface were further confirmed by scanning electron microscope (SEM). The material of PP with the low surface free energy combined with the micro/nano-structures of the surface resulted in the superhydrophobicity of the aluminum alloy surface."
1755629,Ruiperez et al. 2013,"The natural orbital functional theory of the bonding in Cr-2, Mo-2 and W-2","In this paper, we present for the first time a description based on the natural orbital functional theory (NOFT) of the group VI dimers, namely, Cr(2), Mo(2) and W(2). The PNOF5, Piris Natural Orbital Functional, has been used throughout this work, and the results are compared to multireferential perturbation theory (CASPT2) results. Both methods have been combined with effective core potentials to take into account the scalar relativistic effects. In addition, for Cr(2), an all-electron TZVP quality basis set has also been used to recover the core-valence dynamical correlation. In all cases, PNOF5 shows better behavior than CASPT2, which needs a larger basis set to recover comparable amounts of dynamical correlation. PNOF5 is able to account for the non-dynamical electron correlation, which is responsible for the multireferential nature of these dimers. However, it does not fully recover the dynamical correlation, which is crucial for the accurate description of these challenging potential energy curves. Consequently, PNOF5 predicts longer equilibrium distances and lower dissociation energies than the experimental values. Unlike CASPT2, the PNOF5 results do not significantly improve by using larger basis sets. These new findings represent a major step in the NOFT development, since PNOF5 is the first functional of the natural orbitals reported to yield a chemically balanced and accurate description of these challenging transition metal dimers.","The natural orbital functional theory of the bonding in Cr-2, Mo-2 and W-2 Abs: In this paper, we present for the first time a description based on the natural orbital functional theory (NOFT) of the group VI dimers, namely, Cr(2), Mo(2) and W(2). The PNOF5, Piris Natural Orbital Functional, has been used throughout this work, and the results are compared to multireferential perturbation theory (CASPT2) results. Both methods have been combined with effective core potentials to take into account the scalar relativistic effects. In addition, for Cr(2), an all-electron TZVP quality basis set has also been used to recover the core-valence dynamical correlation. In all cases, PNOF5 shows better behavior than CASPT2, which needs a larger basis set to recover comparable amounts of dynamical correlation. PNOF5 is able to account for the non-dynamical electron correlation, which is responsible for the multireferential nature of these dimers. However, it does not fully recover the dynamical correlation, which is crucial for the accurate description of these challenging potential energy curves. Consequently, PNOF5 predicts longer equilibrium distances and lower dissociation energies than the experimental values. Unlike CASPT2, the PNOF5 results do not significantly improve by using larger basis sets. These new findings represent a major step in the NOFT development, since PNOF5 is the first functional of the natural orbitals reported to yield a chemically balanced and accurate description of these challenging transition metal dimers."
1730087,Torkmahalleh et al. 2013,Cr speciation changes in the presence of ozone and reactive oxygen species at low relative humidity,,Cr speciation changes in the presence of ozone and reactive oxygen species at low relative humidity Abs: 
1704050,Horzum et al. 2013,Chitosan fiber-supported zero-valent iron nanoparticles as a novel sorbent for sequestration of inorganic arsenic,,Chitosan fiber-supported zero-valent iron nanoparticles as a novel sorbent for sequestration of inorganic arsenic Abs: 
1668293,Alrehaily et al. 2013,Gamma-radiation induced formation of chromium oxide nanoparticles from dissolved dichromate,"The formation of chromium oxide nanoparticles by gamma radiolysis of Cr(VI) (CrO(4)(2-) or Cr(2)O(7)(2-)) solutions was investigated as a function of pH and initial Cr(VI) concentration by measuring [Cr(VI)], the particle concentration ([Cr(III)(col)]) and [H(2)], and by characterizing the particles using TEM, Raman, FTIR and XPS. The results show that Cr(VI) is easily reduced to Cr(III) by a homogeneous aqueous reaction with ?e(aq)(-), but, due to the stability of Cr(III) colloids, the growth of the Cr(OH)(3) particles is very slow. As the particles grow the interior of the particle dehydrates to form Cr(2)O(3) while the outer layer remains hydrated. When most of the Cr(VI) that is initially present in the solution is converted to Cr(OH)(3) further redox reactions of chromium species occur on the particle surfaces. The redox system reaches a pseudo-equilibrium state due to cyclic reactions of Cr(III) with ?OH and H(2)O(2), and reactions of Cr(VI) with ?e(aq)(-) and H(2)O(2). The size distribution of the particles that are formed is controlled by these solution-solid interface reactions.","Gamma-radiation induced formation of chromium oxide nanoparticles from dissolved dichromate Abs: The formation of chromium oxide nanoparticles by gamma radiolysis of Cr(VI) (CrO(4)(2-) or Cr(2)O(7)(2-)) solutions was investigated as a function of pH and initial Cr(VI) concentration by measuring [Cr(VI)], the particle concentration ([Cr(III)(col)]) and [H(2)], and by characterizing the particles using TEM, Raman, FTIR and XPS. The results show that Cr(VI) is easily reduced to Cr(III) by a homogeneous aqueous reaction with ?e(aq)(-), but, due to the stability of Cr(III) colloids, the growth of the Cr(OH)(3) particles is very slow. As the particles grow the interior of the particle dehydrates to form Cr(2)O(3) while the outer layer remains hydrated. When most of the Cr(VI) that is initially present in the solution is converted to Cr(OH)(3) further redox reactions of chromium species occur on the particle surfaces. The redox system reaches a pseudo-equilibrium state due to cyclic reactions of Cr(III) with ?OH and H(2)O(2), and reactions of Cr(VI) with ?e(aq)(-) and H(2)O(2). The size distribution of the particles that are formed is controlled by these solution-solid interface reactions."
1609662,Brose and  James 2013,Hexavalent chromium reduction in solution and in chromite ore processing residue-enriched soil by tartaric Acid with isopropyl alcohol and divalent manganese as co-reductants,"Chromite ore processing residue (COPR), the solid waste product from the high-temperature alkaline processing of ferrochromite (FeO·CrO), contains Cr(VI) in soluble and insoluble compounds formed in the roasting process. This research investigated tartaric acid in combination with Mn and isopropyl alcohol (IPOH ) as co-reductants for reagent- and COPR-derived Cr(VI). The reduction of Cr(VI) by tartaric acid alone at pH 5.0 or greater was negligible; however, in the presence of Mn or IPOH, reduction occurred in hours. Isopropyl alcohol enhanced Cr(VI) reduction, probably via formation of a termolecular complex with the alcohol, tartaric acid, and Cr(VI). In aqueous solutions of reagent-derived Cr(VI) at pH 4, 12 mmol L tartaric acid with 1.0 mmol L Mn or 1.0 mmol L Mn and 0.29 mol L (2% v/v) IPOH reduced 1.0 mmol L Cr(VI) in 48 h. The same treatments at pH 5.5 reduced 0.60 and 0.58 mmol L Cr(VI) (60%) in 96 h, respectively. A minimum half-life of 10.2 h was calculated from first-order rate constants obtained from Mn and IPOH-Mn co-reductant treatments with tartaric acid at pH 4. The most COPR-derived Cr(VI) reduced in suspension was by IPOH and Mn at high acidity (pH 5.8), which reduced 0.52 mmol L (52%) of the COPR-derived soluble Cr(VI) at 96 h. The enhanced reduction of soluble Cr(VI) by tartaric acid by the addition of Mn proceeds within a complex formed by an esterification reaction between tartaric acid and Cr(VI) with Mn bound to tartaric acid. The combined treatment of tartaric acid, IPOH, Mn, and a strong acid to lower the pH of COPR-enriched soils would be effective in field applications of this chemistry. By creating a slurry of the field soil with these amendments, mass transfer limitations would be overcome, and Cr(VI) would be reduced to Cr(III) in days.","Hexavalent chromium reduction in solution and in chromite ore processing residue-enriched soil by tartaric Acid with isopropyl alcohol and divalent manganese as co-reductants Abs: Chromite ore processing residue (COPR), the solid waste product from the high-temperature alkaline processing of ferrochromite (FeO·CrO), contains Cr(VI) in soluble and insoluble compounds formed in the roasting process. This research investigated tartaric acid in combination with Mn and isopropyl alcohol (IPOH ) as co-reductants for reagent- and COPR-derived Cr(VI). The reduction of Cr(VI) by tartaric acid alone at pH 5.0 or greater was negligible; however, in the presence of Mn or IPOH, reduction occurred in hours. Isopropyl alcohol enhanced Cr(VI) reduction, probably via formation of a termolecular complex with the alcohol, tartaric acid, and Cr(VI). In aqueous solutions of reagent-derived Cr(VI) at pH 4, 12 mmol L tartaric acid with 1.0 mmol L Mn or 1.0 mmol L Mn and 0.29 mol L (2% v/v) IPOH reduced 1.0 mmol L Cr(VI) in 48 h. The same treatments at pH 5.5 reduced 0.60 and 0.58 mmol L Cr(VI) (60%) in 96 h, respectively. A minimum half-life of 10.2 h was calculated from first-order rate constants obtained from Mn and IPOH-Mn co-reductant treatments with tartaric acid at pH 4. The most COPR-derived Cr(VI) reduced in suspension was by IPOH and Mn at high acidity (pH 5.8), which reduced 0.52 mmol L (52%) of the COPR-derived soluble Cr(VI) at 96 h. The enhanced reduction of soluble Cr(VI) by tartaric acid by the addition of Mn proceeds within a complex formed by an esterification reaction between tartaric acid and Cr(VI) with Mn bound to tartaric acid. The combined treatment of tartaric acid, IPOH, Mn, and a strong acid to lower the pH of COPR-enriched soils would be effective in field applications of this chemistry. By creating a slurry of the field soil with these amendments, mass transfer limitations would be overcome, and Cr(VI) would be reduced to Cr(III) in days."
1597384,Bazrafshan et al. 2013,Removal of Arsenic from Aqueous Environments Using Moringa peregrina Seed Extract as a Natural Coagulant,"Arsenic is considered as one of the most hazardous elements for the living Organisms and its presence in natural waters,, can result in serious environmental :problems. In this study, Moringa peregrina seed extract ability in a batch system: to remove arsenate from aqueous solutions was investigated. The effects of major operating variable such as coagulant dose (0.1-5 mL L-1) and pH (2-11) were investigated The optimum pH for removal of arsenic by coagulation using Moringa peregrina seed extract was 6 and the highest removal was found to he 98.61, 99.032 and 98.976% at initial arsenic(V) concentration 100, 200 and 500 mu g L-1 respectively, as a result of precipitation, co-precipitation and adsorption mechanisms. According to achieved results, it was defined that Moringa peregrina seed extract not only was an inexpensive coagulant but also a quite effective factor in removal of arsenic(V)from aqueous environments","Removal of Arsenic from Aqueous Environments Using Moringa peregrina Seed Extract as a Natural Coagulant Abs: Arsenic is considered as one of the most hazardous elements for the living Organisms and its presence in natural waters,, can result in serious environmental :problems. In this study, Moringa peregrina seed extract ability in a batch system: to remove arsenate from aqueous solutions was investigated. The effects of major operating variable such as coagulant dose (0.1-5 mL L-1) and pH (2-11) were investigated The optimum pH for removal of arsenic by coagulation using Moringa peregrina seed extract was 6 and the highest removal was found to he 98.61, 99.032 and 98.976% at initial arsenic(V) concentration 100, 200 and 500 mu g L-1 respectively, as a result of precipitation, co-precipitation and adsorption mechanisms. According to achieved results, it was defined that Moringa peregrina seed extract not only was an inexpensive coagulant but also a quite effective factor in removal of arsenic(V)from aqueous environments"
1597377,Wu et al. 2013,"Comparative and competitive adsorption of Cr(VI), As(III), and Ni(II) onto coconut charcoal","This study evaluates the behavior of coconut charcoal (AC) to adsorb Cr(VI), As(III), and Ni(II) in mono- and multicomponent (binary and ternary) systems. Batch experiments were carried out for mono- and multicomponent systems with varying metal ion concentrations to investigate the competitive adsorption characteristics. The adsorption kinetics followed the mechanism of the pseudo-second-order equation in both single and binary systems, indicating chemical sorption as the rate-limiting step of adsorption mechanism. Equilibrium studies showed that the adsorption of Cr(VI), As(III), and Ni(II) followed the Langmuir model and maximum adsorption capacities were found to be 5.257, 0.042, and 1.748 mg/g, respectively. In multicomponent system, As(III) and Ni(II) adsorption competed intensely, while Cr(VI) adsorption was much less affected by competition than As(III) and Ni(II). With the presence of Cr(VI), the adsorption capacities of As(III) and Ni(II) on AC were higher than those in single system and the metal sorption followed the order of Ni(II) &gt; As(III) &gt; Cr(VI). The results from the sequential adsorption-desorption cycles showed that AC adsorbent held good desorption and reusability.","Comparative and competitive adsorption of Cr(VI), As(III), and Ni(II) onto coconut charcoal Abs: This study evaluates the behavior of coconut charcoal (AC) to adsorb Cr(VI), As(III), and Ni(II) in mono- and multicomponent (binary and ternary) systems. Batch experiments were carried out for mono- and multicomponent systems with varying metal ion concentrations to investigate the competitive adsorption characteristics. The adsorption kinetics followed the mechanism of the pseudo-second-order equation in both single and binary systems, indicating chemical sorption as the rate-limiting step of adsorption mechanism. Equilibrium studies showed that the adsorption of Cr(VI), As(III), and Ni(II) followed the Langmuir model and maximum adsorption capacities were found to be 5.257, 0.042, and 1.748 mg/g, respectively. In multicomponent system, As(III) and Ni(II) adsorption competed intensely, while Cr(VI) adsorption was much less affected by competition than As(III) and Ni(II). With the presence of Cr(VI), the adsorption capacities of As(III) and Ni(II) on AC were higher than those in single system and the metal sorption followed the order of Ni(II) &gt; As(III) &gt; Cr(VI). The results from the sequential adsorption-desorption cycles showed that AC adsorbent held good desorption and reusability."
1597316,Wang et al. ,Simultaneous Redox Conversion of Chromium(VI) and Arsenic(III) under Acidic Conditions,"Arsenic and chromium are often abundant constituents of acid mine drainage (AMD) and are most harmful as arsenite (As(III)) and hexavalent (Cr(VI)). To simultaneously change their oxidation state from As(III) to As(V), and Cr(VI) to Cr(III), is a potentially effective and attractive strategy for environmental remediation. The coabundance of As(III) and Cr(VI) in natural environments indicates their negligible direct interaction. The addition of H2O2 enables and greatly accelerates the simultaneous oxidation of As(III) and reduction of Cr(VI). These reactions are further enhanced at acidic pH and higher concentrations of Cr(VI). However, the presence of ligands (i.e., oxalate, citrate, pyrophosphate) greatly retards the oxidation of As(III), even though it enhances the reduction of Cr(VI). To explain these results we propose a reaction mechanism where Cr(VI) is primarily reduced to Cr(III) by H2O2, via the intermediate tetraperoxochromate Cr(V). Cr(V) is then involved in the formation of (•)OH radicals. In the presence of ligands, the capacity of Cr(V) to form (•)OH radicals, which are primarily responsible for As(III) oxidation, is practically inhibited. Our findings demonstrate the feasibility for the coconversion of As(III) and Cr(VI) in AMD and real-world constraints to this strategy for environmental remediation.","Simultaneous Redox Conversion of Chromium(VI) and Arsenic(III) under Acidic Conditions Abs: Arsenic and chromium are often abundant constituents of acid mine drainage (AMD) and are most harmful as arsenite (As(III)) and hexavalent (Cr(VI)). To simultaneously change their oxidation state from As(III) to As(V), and Cr(VI) to Cr(III), is a potentially effective and attractive strategy for environmental remediation. The coabundance of As(III) and Cr(VI) in natural environments indicates their negligible direct interaction. The addition of H2O2 enables and greatly accelerates the simultaneous oxidation of As(III) and reduction of Cr(VI). These reactions are further enhanced at acidic pH and higher concentrations of Cr(VI). However, the presence of ligands (i.e., oxalate, citrate, pyrophosphate) greatly retards the oxidation of As(III), even though it enhances the reduction of Cr(VI). To explain these results we propose a reaction mechanism where Cr(VI) is primarily reduced to Cr(III) by H2O2, via the intermediate tetraperoxochromate Cr(V). Cr(V) is then involved in the formation of (•)OH radicals. In the presence of ligands, the capacity of Cr(V) to form (•)OH radicals, which are primarily responsible for As(III) oxidation, is practically inhibited. Our findings demonstrate the feasibility for the coconversion of As(III) and Cr(VI) in AMD and real-world constraints to this strategy for environmental remediation."
1584937,Saeedi et al. 2013,Effect of Alternative Electrolytes on Enhanced Electrokinetic Remediation of Hexavalent Chromium in Clayey Soil,"Hexavalent chromium is mobile and hazardous in the environment Electrokinetic remediation of chromium (IV)-contaminated soils is intended either to remove or to reduce Cr (VI) to Cr (III). This study examines the effectiveness of utilizing EDTA and acetic acid solutions as alternative electrolytes in the electrokinetic (EK) process, with coupled nano-scale zero-valent iron (nZVI) as a barrier for the remediation of Cr (VI)-contaminated clay. An nZVI barrier was installed adjacent to the anode, and different electrolyte solutions (0.1 M EDTA and 1 M acetic acid) were used to investigate the effect of both on the electrokinetic remediation efficiency. Soil was contaminated to 300 ppm of Cr (IV), and a constant DC voltage gradient of I V/cm was applied to the soil sample for 72 h. It was found that an nZVI permeable reactive barrier (PRJB) could improve the Cr (VI) remediation efficiency and reduce electrical energy consumption. Results also showed that acetic acid as electrolyte promoted the reduction of Cr (VI) to Cr (III), while EDTA application as electrolyte led to more chromium removal and reduction than an EK-nZVI barrier.","Effect of Alternative Electrolytes on Enhanced Electrokinetic Remediation of Hexavalent Chromium in Clayey Soil Abs: Hexavalent chromium is mobile and hazardous in the environment Electrokinetic remediation of chromium (IV)-contaminated soils is intended either to remove or to reduce Cr (VI) to Cr (III). This study examines the effectiveness of utilizing EDTA and acetic acid solutions as alternative electrolytes in the electrokinetic (EK) process, with coupled nano-scale zero-valent iron (nZVI) as a barrier for the remediation of Cr (VI)-contaminated clay. An nZVI barrier was installed adjacent to the anode, and different electrolyte solutions (0.1 M EDTA and 1 M acetic acid) were used to investigate the effect of both on the electrokinetic remediation efficiency. Soil was contaminated to 300 ppm of Cr (IV), and a constant DC voltage gradient of I V/cm was applied to the soil sample for 72 h. It was found that an nZVI permeable reactive barrier (PRJB) could improve the Cr (VI) remediation efficiency and reduce electrical energy consumption. Results also showed that acetic acid as electrolyte promoted the reduction of Cr (VI) to Cr (III), while EDTA application as electrolyte led to more chromium removal and reduction than an EK-nZVI barrier."
1583773,Yang et al. 2013,Visible-light-induced photocatalytic reduction of Cr(VI) with coupled Bi2O3/TiO2 photocatalyst and the synergistic bisphenol A oxidation,"Coupled Bi2O3/TiO2 photocatalysts were fabricated by sol-gel and hydrothermal methods and characterized using various spectroscopy techniques. Photocatalytic reduction of Cr(VI) in aqueous solution, together with the synergistic effect of photodegradation of bisphenol A (BPA), was investigated using these coupled Bi2O3/TiO2 under visible-light irradiation. Coupling of Bi2O3 inhibited the phase transformation from anatase to rutile and extended absorption region to visible light. Bi ions did not enter TiO2 lattice and were more likely to bond with oxygen atoms to form Bi2O3 on the surface of TiO2. Photovoltage signals in visible range revealed the effective interfacial charge transfer between Bi2O3 and TiO2. Two percent Bi2O3/TiO2 exhibited the highest photocatalytic activity of visible-light-induced reduction of Cr(VI). The addition of BPA effectively increased the photocatalytic reduction of Cr(VI). Simultaneously, the presence of Cr(VI) promoted the degradation of BPA, which was demonstrated by the investigation of TOC removal yield and generated intermediates. A possible mechanism of photocatalytic reduction of Cr(VI) and degradation of BPA in Bi2O3/TiO2 system was proposed. The synergistic effect, observed between reduction of Cr(VI) and degradation of BPA, provides beneficial method for environmental remediation and purification of the complex wastewater.","Visible-light-induced photocatalytic reduction of Cr(VI) with coupled Bi2O3/TiO2 photocatalyst and the synergistic bisphenol A oxidation Abs: Coupled Bi2O3/TiO2 photocatalysts were fabricated by sol-gel and hydrothermal methods and characterized using various spectroscopy techniques. Photocatalytic reduction of Cr(VI) in aqueous solution, together with the synergistic effect of photodegradation of bisphenol A (BPA), was investigated using these coupled Bi2O3/TiO2 under visible-light irradiation. Coupling of Bi2O3 inhibited the phase transformation from anatase to rutile and extended absorption region to visible light. Bi ions did not enter TiO2 lattice and were more likely to bond with oxygen atoms to form Bi2O3 on the surface of TiO2. Photovoltage signals in visible range revealed the effective interfacial charge transfer between Bi2O3 and TiO2. Two percent Bi2O3/TiO2 exhibited the highest photocatalytic activity of visible-light-induced reduction of Cr(VI). The addition of BPA effectively increased the photocatalytic reduction of Cr(VI). Simultaneously, the presence of Cr(VI) promoted the degradation of BPA, which was demonstrated by the investigation of TOC removal yield and generated intermediates. A possible mechanism of photocatalytic reduction of Cr(VI) and degradation of BPA in Bi2O3/TiO2 system was proposed. The synergistic effect, observed between reduction of Cr(VI) and degradation of BPA, provides beneficial method for environmental remediation and purification of the complex wastewater."
1579373,Majumdar et al. 2013,Metal Impregnated Silica-Carbon Materials from Rice Husk: A Versatile Sorbent for Toxic Organics and Inorganics in Water and Air,,Metal Impregnated Silica-Carbon Materials from Rice Husk: A Versatile Sorbent for Toxic Organics and Inorganics in Water and Air Abs: 
1579349,Fresquez et al. ,Establishment of Toxic Metal Reference Range in Tobacco from US Cigarettes,"Smoking remains the leading cause of preventable death in the United States. There are numerous harmful substances in tobacco and tobacco smoke. Among the more than 4,000 identified compounds in smoke, many metals contribute to the health risks associated with tobacco use. Specific metals found in tobacco and tobacco smoke have been classified as carcinogens by the International Agency for Research on Cancer. Exposure to toxic metals can cause outcomes including inflammation, sensitization and carcinogenesis. Metals in tobacco are transported in tobacco smoke proportionally with their concentrations in tobacco filler for a given cigarette design. To quantitatively examine the metal content in numerous tobacco products, high throughput methods are desired. This study developed a simple, rapid tobacco digestion method coupled with a sensitive analytical method using inductively coupled plasma-mass spectrometry. Because of known memory effects and volatility of mercury, quantitative determinations of mercury were made with a direct combustion analyzer. The methods were utilized to examine arsenic, beryllium, cadmium, chromium, cobalt, lead, manganese, mercury and nickel contents in cigarette tobacco and to establish a reference range for the metals in 50 varieties of cigarettes available in the US. These results are comparable to the limited data sets reported by others and with available standard reference material values.","Establishment of Toxic Metal Reference Range in Tobacco from US Cigarettes Abs: Smoking remains the leading cause of preventable death in the United States. There are numerous harmful substances in tobacco and tobacco smoke. Among the more than 4,000 identified compounds in smoke, many metals contribute to the health risks associated with tobacco use. Specific metals found in tobacco and tobacco smoke have been classified as carcinogens by the International Agency for Research on Cancer. Exposure to toxic metals can cause outcomes including inflammation, sensitization and carcinogenesis. Metals in tobacco are transported in tobacco smoke proportionally with their concentrations in tobacco filler for a given cigarette design. To quantitatively examine the metal content in numerous tobacco products, high throughput methods are desired. This study developed a simple, rapid tobacco digestion method coupled with a sensitive analytical method using inductively coupled plasma-mass spectrometry. Because of known memory effects and volatility of mercury, quantitative determinations of mercury were made with a direct combustion analyzer. The methods were utilized to examine arsenic, beryllium, cadmium, chromium, cobalt, lead, manganese, mercury and nickel contents in cigarette tobacco and to establish a reference range for the metals in 50 varieties of cigarettes available in the US. These results are comparable to the limited data sets reported by others and with available standard reference material values."
1578526,Brandt-Rauf 2006,Editorial retraction. Cancer mortality in a Chinese population exposed to hexavalent chromium in water,"It has been brought to our attention that an article published in JOEM in the April, 1997 issue by Zhang and Li 1 failed to meet the journal’s published editorial policy in effect at that time. Specifically, financial and intellectual input to the paper by outside parties was not disclosed. Although it is impossible to know what the impact of such disclosure would have been, it is possible that full knowledge of the circumstances may have altered the review process or the subsequent interpretation of the study by readers. Therefore, after thorough investigation, consultation with outside experts and consideration by the Editorial Board, I have decided that retraction is necessary. It should be understood that there is no evidence to suggest the existence of scientific fraud in this work and that the factual content of the article has not been re-evaluated. This decision is based solely on the violation of the journal’s policy regarding disclosure. The corresponding author of this article (Dr. Zhang) has since died. However, the co-author (Dr. Li) has been informed of this decision. We will also make appropriate notification to the National Library of Medicine regarding future citation of this paper.","Editorial retraction. Cancer mortality in a Chinese population exposed to hexavalent chromium in water Abs: It has been brought to our attention that an article published in JOEM in the April, 1997 issue by Zhang and Li 1 failed to meet the journal’s published editorial policy in effect at that time. Specifically, financial and intellectual input to the paper by outside parties was not disclosed. Although it is impossible to know what the impact of such disclosure would have been, it is possible that full knowledge of the circumstances may have altered the review process or the subsequent interpretation of the study by readers. Therefore, after thorough investigation, consultation with outside experts and consideration by the Editorial Board, I have decided that retraction is necessary. It should be understood that there is no evidence to suggest the existence of scientific fraud in this work and that the factual content of the article has not been re-evaluated. This decision is based solely on the violation of the journal’s policy regarding disclosure. The corresponding author of this article (Dr. Zhang) has since died. However, the co-author (Dr. Li) has been informed of this decision. We will also make appropriate notification to the National Library of Medicine regarding future citation of this paper."
1578294,Zhang et al. 1997,Solidification/stabilization applied to chromium species,"It is not easy to stabilize Cr(VI) in treatment systems for waste or wastewater unless it is reduced to Cr(III). Ferrous sulfate is a effective reducing reagent, and can produce stable coprecipitate products like (CrxFe1-x)(OH)(3). In a cement-based S/S system, various iron salts are effective at reducing Cr leachabilities, as shown by the TCLP leaching procedure after both short and long cure times. For appropriate contents and time, the leachate concentrations can be brought below the EPA characteristic limit of 5 mg/L. The addition of ferrous sulfate has been investigated in most detail, and Si-29 MAS NMR shows retarded hydration by Cr salts alone, or by ferrous sulfate alone or in combination with Cr salts. In addition to retarded hydration, the added ferrous sulfate results in enhanced amounts of chain-lengthening and chain-branching silicates, and several explanations are possible for these effects. Leaching behavior of cement-based S/S samples prepared with binary mixtures of Cr salts with lead and arsenic show synergistic effects that may be due to formation of insoluble salts or to redox chemistry. Cr(III) and Cr(VI) both enhance immobilization of lead, but compromise immobilization of sodium arsenite. Cr(VI) leachability is reduced in the presence of either Pb(II) or As(III).","Solidification/stabilization applied to chromium species Abs: It is not easy to stabilize Cr(VI) in treatment systems for waste or wastewater unless it is reduced to Cr(III). Ferrous sulfate is a effective reducing reagent, and can produce stable coprecipitate products like (CrxFe1-x)(OH)(3). In a cement-based S/S system, various iron salts are effective at reducing Cr leachabilities, as shown by the TCLP leaching procedure after both short and long cure times. For appropriate contents and time, the leachate concentrations can be brought below the EPA characteristic limit of 5 mg/L. The addition of ferrous sulfate has been investigated in most detail, and Si-29 MAS NMR shows retarded hydration by Cr salts alone, or by ferrous sulfate alone or in combination with Cr salts. In addition to retarded hydration, the added ferrous sulfate results in enhanced amounts of chain-lengthening and chain-branching silicates, and several explanations are possible for these effects. Leaching behavior of cement-based S/S samples prepared with binary mixtures of Cr salts with lead and arsenic show synergistic effects that may be due to formation of insoluble salts or to redox chemistry. Cr(III) and Cr(VI) both enhance immobilization of lead, but compromise immobilization of sodium arsenite. Cr(VI) leachability is reduced in the presence of either Pb(II) or As(III)."
1578293,Zamboulis et al. 2004,The application of sorptive flotation for the removal of metal ions,"There is a stringent need for the control of toxic metals produced during various production processes and released into the aqueous environment in order to avoid damage relevant to soil or groundwater contamination. Among the available treatment technologies, sorption has been considered of particular importance. In the present study, a synthetic ultrafine zeolite was initially applied as sorbent (in suspension) for the removal of copper and zinc cations, and also chromium(VI) oxyanions - the latter less effectively. The removal of cations by zeolite particles depends mainly on the respective pH value, influencing the aquatic speciation during the process, as well as the zeta-potential values (surface charge) of the system. Flotation was subsequently applied for the efficient (more than 95%) solid/liquid separation of metal-laden sorbents. A suitable surface-active agent(acting as collector) should be added such as sodium dodecyl sulfate, dodecylamine or hexadecyl-trimethyl-ammonium bromide, depending on the specific experimental conditions in order to render hydrophobic and hence, to increase the floatability of solids. As a result, a foam concentrate is produced consisting of the metal-loaded zeolite particles and of purified water as underflow, which could be more easily subjected to further treatment (for instance, by membrane filtration), if necessary. Both the aforementioned technological stages, sorption and flotation, can be operated in the same unit, and the integrated innovative process was termed ""sorptive flotation"".","The application of sorptive flotation for the removal of metal ions Abs: There is a stringent need for the control of toxic metals produced during various production processes and released into the aqueous environment in order to avoid damage relevant to soil or groundwater contamination. Among the available treatment technologies, sorption has been considered of particular importance. In the present study, a synthetic ultrafine zeolite was initially applied as sorbent (in suspension) for the removal of copper and zinc cations, and also chromium(VI) oxyanions - the latter less effectively. The removal of cations by zeolite particles depends mainly on the respective pH value, influencing the aquatic speciation during the process, as well as the zeta-potential values (surface charge) of the system. Flotation was subsequently applied for the efficient (more than 95%) solid/liquid separation of metal-laden sorbents. A suitable surface-active agent(acting as collector) should be added such as sodium dodecyl sulfate, dodecylamine or hexadecyl-trimethyl-ammonium bromide, depending on the specific experimental conditions in order to render hydrophobic and hence, to increase the floatability of solids. As a result, a foam concentrate is produced consisting of the metal-loaded zeolite particles and of purified water as underflow, which could be more easily subjected to further treatment (for instance, by membrane filtration), if necessary. Both the aforementioned technological stages, sorption and flotation, can be operated in the same unit, and the integrated innovative process was termed ""sorptive flotation""."
1578292,Wetterhahn and  Dudek 1996,Environmental metal carcinogens: Genotoxicity and altered gene expression by direct metal-mediated and indirect oxidative pathways,"Environmental exposure to metal carcinogens, such as inorganic chromium and nickel compounds, pose significant human health risks such as toxicity and cancer, Although the exact mechanism(s) of metal-mediated effects is still unknown, substantial evidence now exists that both chromium and nickel compounds can produce cellular effects through two distinct pathways that are related but independent of each other. One pathway is through direct metal binding to either DNA or chromatin-associated proteins while the other indirect oxidative pathway, is through the intracellular generation of oxidants and reactive oxygen species. Although both pathways contribute to DNA damage, the damage is of two significantly different types: chromatin damage directly involving bound metal vs. oxidative damage-induced DNA lesions. The type and amount of the specific DNA damage may vary depending on cell or tissue type. All types of DNA damage can potentially be pre-mutagenic and lead to inappropriate changes in gene expression, which may be critical in the case of oncogenes or tumor suppressor genes, Phenotypic alteration mediated by chromium or nickel compounds can occur in cells through the oxidative pathway as demonstrated by induction of oxidative damage-inducible genes and the activation of the oxidant stress-induced transcription factors, such as NF-kappa B. Future research into the cellular effects of chromium and nickel compounds should provide insight into how each pathway contributes to genotoxicity, altered gene expression and the development of metal-mediated carcinogenesis.","Environmental metal carcinogens: Genotoxicity and altered gene expression by direct metal-mediated and indirect oxidative pathways Abs: Environmental exposure to metal carcinogens, such as inorganic chromium and nickel compounds, pose significant human health risks such as toxicity and cancer, Although the exact mechanism(s) of metal-mediated effects is still unknown, substantial evidence now exists that both chromium and nickel compounds can produce cellular effects through two distinct pathways that are related but independent of each other. One pathway is through direct metal binding to either DNA or chromatin-associated proteins while the other indirect oxidative pathway, is through the intracellular generation of oxidants and reactive oxygen species. Although both pathways contribute to DNA damage, the damage is of two significantly different types: chromatin damage directly involving bound metal vs. oxidative damage-induced DNA lesions. The type and amount of the specific DNA damage may vary depending on cell or tissue type. All types of DNA damage can potentially be pre-mutagenic and lead to inappropriate changes in gene expression, which may be critical in the case of oncogenes or tumor suppressor genes, Phenotypic alteration mediated by chromium or nickel compounds can occur in cells through the oxidative pathway as demonstrated by induction of oxidative damage-inducible genes and the activation of the oxidant stress-induced transcription factors, such as NF-kappa B. Future research into the cellular effects of chromium and nickel compounds should provide insight into how each pathway contributes to genotoxicity, altered gene expression and the development of metal-mediated carcinogenesis."
1578291,Watson et al. 2003,H-1 NMR studies of Cr(III)-imidazole complexes: can H-1 NMR be used as a probe of Cr-guanine DNA adducts?,"Chromate has firmly been established as a mutagen and carcinogen. in addition to potential oxidative damage to DNA resulting from the three one-electron reductions of chromate to Cr(III), the resulting Cr(III) can form DNA adducts. These adducts may also be important in the mutagenic and carcinogenic action of chromate. Cr(III) binds preferentially to guanine-rich DNA segments, and recent studies have indicated that the ion may be complexed to guanine and PO, groups from the DNA backbone. Better spectroscopic probes are needed to examine the binding of Cr(III) to guanine in DNA. The NMR spectra of Cr(III) complexes of guanine or related ligands such as imidazoles have not been reported previously, and paramagnetic H-1 NMR spectra could potentially provide a means for examining Cr-guanine interactions selectively. Unfortunately, using Cr(III)-imidazole complexes as models demonstrates that paramagnetic H-1 NMR has limited potential to probe for these interactions. (C) 2002 Elsevier Science B.V. All rights reserved.","H-1 NMR studies of Cr(III)-imidazole complexes: can H-1 NMR be used as a probe of Cr-guanine DNA adducts? Abs: Chromate has firmly been established as a mutagen and carcinogen. in addition to potential oxidative damage to DNA resulting from the three one-electron reductions of chromate to Cr(III), the resulting Cr(III) can form DNA adducts. These adducts may also be important in the mutagenic and carcinogenic action of chromate. Cr(III) binds preferentially to guanine-rich DNA segments, and recent studies have indicated that the ion may be complexed to guanine and PO, groups from the DNA backbone. Better spectroscopic probes are needed to examine the binding of Cr(III) to guanine in DNA. The NMR spectra of Cr(III) complexes of guanine or related ligands such as imidazoles have not been reported previously, and paramagnetic H-1 NMR spectra could potentially provide a means for examining Cr-guanine interactions selectively. Unfortunately, using Cr(III)-imidazole complexes as models demonstrates that paramagnetic H-1 NMR has limited potential to probe for these interactions. (C) 2002 Elsevier Science B.V. All rights reserved."
1578290,Wang et al. 2000,Removal of Cr(VI) from aqueous solution by macroporous resin adsorption,"The removal of Cr(VI) by macroporous anion exchange resin adsorption was investigated. Batch adsorption studies demonstrate that the resin has a significant capacity for adsorption of Cr(VI) from aqueous solution. The parameters investigated in this study included pH, contact time, initial chromium concentration, resin dosage and temperature. The adsorption process of Cr(VI) can be described by Langmuir isotherm and Freundlich isotherm model. Application of the Langmuir isotherm to the systems yielded maximum adsorption capacity of 53.03 mg/g resin. The specific surface areas of the macroporous resin was calculated to be 47.35 m(2)/g. The kinetics and thermodynamic parameters were also evaluated. It was found that the separation process is partly diffusion controlled. The mass transfer coefficient was calculated to be 8.62x10(-5) cm/s. The activation energy and change of enthalpy were evaluated and found to be 4.81 kcal/mol and 8.79 kcal/mol at the temperature of 25 degrees C, respectively. The free energy of the process was small but positive, and it decreases with an increase of temperature. The change of entropy was found to be small and remains almost unchanged over the 20 to 35 degrees C temperature range. The desorption studies are also performed and the results show that the Cr(VI) adsorbed by macroporous resin can be eluted by 4 M NaOH. This suggested that the resin saturated with chromium can be regenerated by NaOH solution.","Removal of Cr(VI) from aqueous solution by macroporous resin adsorption Abs: The removal of Cr(VI) by macroporous anion exchange resin adsorption was investigated. Batch adsorption studies demonstrate that the resin has a significant capacity for adsorption of Cr(VI) from aqueous solution. The parameters investigated in this study included pH, contact time, initial chromium concentration, resin dosage and temperature. The adsorption process of Cr(VI) can be described by Langmuir isotherm and Freundlich isotherm model. Application of the Langmuir isotherm to the systems yielded maximum adsorption capacity of 53.03 mg/g resin. The specific surface areas of the macroporous resin was calculated to be 47.35 m(2)/g. The kinetics and thermodynamic parameters were also evaluated. It was found that the separation process is partly diffusion controlled. The mass transfer coefficient was calculated to be 8.62x10(-5) cm/s. The activation energy and change of enthalpy were evaluated and found to be 4.81 kcal/mol and 8.79 kcal/mol at the temperature of 25 degrees C, respectively. The free energy of the process was small but positive, and it decreases with an increase of temperature. The change of entropy was found to be small and remains almost unchanged over the 20 to 35 degrees C temperature range. The desorption studies are also performed and the results show that the Cr(VI) adsorbed by macroporous resin can be eluted by 4 M NaOH. This suggested that the resin saturated with chromium can be regenerated by NaOH solution."
1578289,Wallen 1996,Adaptation of the growth of the diatom Fragilaria crotonensis (Kitton) and the phytoplankton assemblage of Lake Erie to chromium toxicity,"BIOSIS COPYRIGHT: BIOL ABS. Growth of the natural phytoplankton assemblages and the diatom Fragilaria crotonensis Kitton within the assemblage, in the presence of Cr(VI) from the control (0 muM) to 2.5 muM were measured for 40 days. Experiments were conducted in the summer and the winter. Chromium inhibited growth and this inhibition varied. Sensitivity was greater, at higher concentrations of Cr(VI), when the algae were exposed to the lower irradiation and temperature of winter, and varied with species. The toxicity effect was greater on F. crotonensis than the phytoplankton assemblage. At the highest concentration used, there was a shift in species of the assemblage from domination of diatoms to green algae.","Adaptation of the growth of the diatom Fragilaria crotonensis (Kitton) and the phytoplankton assemblage of Lake Erie to chromium toxicity Abs: BIOSIS COPYRIGHT: BIOL ABS. Growth of the natural phytoplankton assemblages and the diatom Fragilaria crotonensis Kitton within the assemblage, in the presence of Cr(VI) from the control (0 muM) to 2.5 muM were measured for 40 days. Experiments were conducted in the summer and the winter. Chromium inhibited growth and this inhibition varied. Sensitivity was greater, at higher concentrations of Cr(VI), when the algae were exposed to the lower irradiation and temperature of winter, and varied with species. The toxicity effect was greater on F. crotonensis than the phytoplankton assemblage. At the highest concentration used, there was a shift in species of the assemblage from domination of diatoms to green algae."
1578288,Vladescu and  Pascu 2005,Ion exchange-spectrometry coupled method for the speciation and determination of the chromium content in the white wines,"In this paper there is presented a ion exchange - molecular absorption spectrometry in visible coupled method, which allows not only the determination of the concentration of chromium in wine but also the setting of the oxidation state this element in white wine samples. The method consists in separating Cr (VI) - if it is present in wine - and concentrating Cr (III) using a strongly acid cation exchange resin in the ionic form H3O+, followed by their quantitative determination by molecular absorption spectrometry in visible with diphenylcarbazide DFC in acid medium and water-acetone mixed solvent). The method was validated on only one wine variety, Riesling Italian 1999, and it was applied on wine samples of different varieties and crop years. The proposed method was applied in order to analyse some wine samples of different varieties and age, produced by the Nine - Growing and Wine - Making Research and Development Station Dragasani between 1996 - 2000. It was experimentally showed that the analysed wines contain Cr (III) and do not contain Cr (VI) which is very toxic; the chromium concentration was in all the wines under the admitted limit specified in the current legislation.","Ion exchange-spectrometry coupled method for the speciation and determination of the chromium content in the white wines Abs: In this paper there is presented a ion exchange - molecular absorption spectrometry in visible coupled method, which allows not only the determination of the concentration of chromium in wine but also the setting of the oxidation state this element in white wine samples. The method consists in separating Cr (VI) - if it is present in wine - and concentrating Cr (III) using a strongly acid cation exchange resin in the ionic form H3O+, followed by their quantitative determination by molecular absorption spectrometry in visible with diphenylcarbazide DFC in acid medium and water-acetone mixed solvent). The method was validated on only one wine variety, Riesling Italian 1999, and it was applied on wine samples of different varieties and crop years. The proposed method was applied in order to analyse some wine samples of different varieties and age, produced by the Nine - Growing and Wine - Making Research and Development Station Dragasani between 1996 - 2000. It was experimentally showed that the analysed wines contain Cr (III) and do not contain Cr (VI) which is very toxic; the chromium concentration was in all the wines under the admitted limit specified in the current legislation."
1578287,Vitale et al. 1997,Cr(VI) soil analytical method: A reliable analytical method for extracting and quantifying Cr(VI) in soils,"BIOSIS COPYRIGHT: BIOL ABS. Chromium has been used in the industrialized world in many applications for more than a century. Chromium is a trace metallic element found in the Earth's crust, and when it is found in concentrated ore deposits it is principally as FeCr2O4 (chromite ore). In the environment, chromium is typically found in the trivalent and hexavalent states. These two oxidation states have differing toxicities and mobiles. Hexavalent chromium (Cr(VI)) is classified as a known human carcinogen (via inhalation) and is rather mobile, whereas trivalent chromium (Cr(III)) is comparatively benign (it is an essential dietary element for humans) and relatively immobile. This significant toxicological and geochemical disparity between the two valence states necessitates that environmental investigators be able to quantitatively distinguish between these two forms in solid environmental media. Several regulatory-approved analytical techniques exist for the quantitative differentiation between C","Cr(VI) soil analytical method: A reliable analytical method for extracting and quantifying Cr(VI) in soils Abs: BIOSIS COPYRIGHT: BIOL ABS. Chromium has been used in the industrialized world in many applications for more than a century. Chromium is a trace metallic element found in the Earth's crust, and when it is found in concentrated ore deposits it is principally as FeCr2O4 (chromite ore). In the environment, chromium is typically found in the trivalent and hexavalent states. These two oxidation states have differing toxicities and mobiles. Hexavalent chromium (Cr(VI)) is classified as a known human carcinogen (via inhalation) and is rather mobile, whereas trivalent chromium (Cr(III)) is comparatively benign (it is an essential dietary element for humans) and relatively immobile. This significant toxicological and geochemical disparity between the two valence states necessitates that environmental investigators be able to quantitatively distinguish between these two forms in solid environmental media. Several regulatory-approved analytical techniques exist for the quantitative differentiation between C"
1578286,Vitale et al. 1994,HEXAVALENT CHROMIUM EXTRACTION FROM SOILS - EVALUATION OF AN ALKALINE DIGESTION METHOD,"The accurate quantification of total CR(VI) in soils is relevant to human health concerns because Cr(VI)) is significantly more toxic than Cr(III). Hot alkaline solution has been shown to extract soluble and insoluble forms of Cr(VI) from soils, but incomplete recovery of Cr(VI) spikes and the oxidation of soluble Cr(III) spikes in certain soils have been suggested as method deficiencies. A laboratory method study was performed to (i) test the method's accuracy, (ii) understand the soil chemical processes responsible for poor Cr(VI) spike recoveries, and (iii) develop definitive interpretations for Cr(Vn spike recovery data. Test results for >1500 field soil samples and the method study of eight diverse soil materials demonstrated dissolution of soluble and insoluble Cr(VI) spikes and the method's reliability for Cr(VI)) characterization. Complete dissolution of K2CrO4, BaCrO4, and PbCrO4 spikes confirmed the extraction of soluble and insoluble Cr(VI)) forms. Ancillary soil chemical parameters, including oxidation-reduction potential (ORP) (reported herein as E(h)), pH, S2-, and total organic C were quantified and interpreted to explain poor Cr(Vr) spike recoveries. Highly reducing samples yielded 0% Cr(VI) spike recoveries, as predicted from E(h)-pH relationships, and unspiked soil samples contained no detectable Cr(VI). In soils containing Cr(VI) and in most aerobic soils without native Cr(VI), acceptable Cr(VI) spike recoveries were obtained. Ancillary parameter characterization demonstrated that strongly reducing samples cannot maintain Cr(VI) laboratory matrix spikes. Correct interpretation of poor Cr(VI) spike recovery data should avoid labeling these data as unacceptable method results without ancillary parameter characterization of such samples.","HEXAVALENT CHROMIUM EXTRACTION FROM SOILS - EVALUATION OF AN ALKALINE DIGESTION METHOD Abs: The accurate quantification of total CR(VI) in soils is relevant to human health concerns because Cr(VI)) is significantly more toxic than Cr(III). Hot alkaline solution has been shown to extract soluble and insoluble forms of Cr(VI) from soils, but incomplete recovery of Cr(VI) spikes and the oxidation of soluble Cr(III) spikes in certain soils have been suggested as method deficiencies. A laboratory method study was performed to (i) test the method's accuracy, (ii) understand the soil chemical processes responsible for poor Cr(VI) spike recoveries, and (iii) develop definitive interpretations for Cr(Vn spike recovery data. Test results for >1500 field soil samples and the method study of eight diverse soil materials demonstrated dissolution of soluble and insoluble Cr(VI) spikes and the method's reliability for Cr(VI)) characterization. Complete dissolution of K2CrO4, BaCrO4, and PbCrO4 spikes confirmed the extraction of soluble and insoluble Cr(VI)) forms. Ancillary soil chemical parameters, including oxidation-reduction potential (ORP) (reported herein as E(h)), pH, S2-, and total organic C were quantified and interpreted to explain poor Cr(Vr) spike recoveries. Highly reducing samples yielded 0% Cr(VI) spike recoveries, as predicted from E(h)-pH relationships, and unspiked soil samples contained no detectable Cr(VI). In soils containing Cr(VI) and in most aerobic soils without native Cr(VI), acceptable Cr(VI) spike recoveries were obtained. Ancillary parameter characterization demonstrated that strongly reducing samples cannot maintain Cr(VI) laboratory matrix spikes. Correct interpretation of poor Cr(VI) spike recovery data should avoid labeling these data as unacceptable method results without ancillary parameter characterization of such samples."
1578285,Vanheerden et al. 1994,DEATH BY TANNING - A CASE OF FATAL BASIC CHROMIUM SULFATE POISONING,"A woman ingested 400 ml of leather tanning solution containing 48 g of basic chromium sulphate (CrOHSO4). This substance forms hydrogen ions and trivalent chromium when it reacts with tissue proteins. The patient died of cardiogenic shock, complicated by pancreatitis and gut mucosal necrosis and haemorrhage. There are no reported cases of toxicity due to oral ingestion of trivalent chromium. Toxicity of hexavalent and trivalent chromium is dicussed and suggestions made for management of future cases.","DEATH BY TANNING - A CASE OF FATAL BASIC CHROMIUM SULFATE POISONING Abs: A woman ingested 400 ml of leather tanning solution containing 48 g of basic chromium sulphate (CrOHSO4). This substance forms hydrogen ions and trivalent chromium when it reacts with tissue proteins. The patient died of cardiogenic shock, complicated by pancreatitis and gut mucosal necrosis and haemorrhage. There are no reported cases of toxicity due to oral ingestion of trivalent chromium. Toxicity of hexavalent and trivalent chromium is dicussed and suggestions made for management of future cases."
1578284,Utkarsh and  Suresh 2011,Kinetic and Equilibrium Studies of Cr (VI) Removal from Aqueous Solutions using Activated Neem Bark,"Hexavalent chromium [Cr(VI)] has a dominant presence in most of the effluent streams as compared to other heavy metal ions coming out from the different industries such as metal finishing, tannery, electroplating etc. Due to its carcinogenic and toxic nature, it is considered as one of the most important environmental problems. The solution for this problem is a cost effective and eco-friendly treatment technique. Various treatment techniques such as chemical precipitation, ion exchange, membrane separation, electro-coagulation and chemical reduction are available to reduce the contamination of Cr(VI) in the effluent streams. These techniques are not eco-friendly and economically viable for the large volume of wastewater ireatment. Adsorption using low cost adsorbents is found to be (me of the cost effective technique for Cr(VI) removal from the effluent streams. In the present study, a waste biodegradable material, neem bark, is used. This neem bark is activated using concenirated sulphuric acid (98 wt%) and is used as an adsorbent for Cr(VI) removal from aqueous solutions. Batch adsorption experiments were conducted for determining the performance of activated neem bark for removal of Cr(VI). The effect of various important parameters such as effect of contact time, initial Cr(VI) concentration and dosage of adsorbent for the removal of Cr(VI) using activated neem bark adsorbent are studied. The kinetic studies show 70% removal of Cr(VI) using activated neem bark as an adsorbent while keeping 100 mg/L of initial Cr(VI) concentration The equilibrium data for the adsorption of Cr(VI) on activated neem bark is being tested with Langmuir isotherm model and Freundlich isotherm model. It is observed that it is following the Langmuir isotherm model and the corresponding adsorption capacity of activated neem bark is 26.95 mg/g. Pseudo first-order and second-order rate kinetic models are used to evaluate the mechanism of adsorption of Cr(VI) on activated neem bark It is observed that the adsorption of Cr(VI) on activated neon bark follows second order kinetics.","Kinetic and Equilibrium Studies of Cr (VI) Removal from Aqueous Solutions using Activated Neem Bark Abs: Hexavalent chromium [Cr(VI)] has a dominant presence in most of the effluent streams as compared to other heavy metal ions coming out from the different industries such as metal finishing, tannery, electroplating etc. Due to its carcinogenic and toxic nature, it is considered as one of the most important environmental problems. The solution for this problem is a cost effective and eco-friendly treatment technique. Various treatment techniques such as chemical precipitation, ion exchange, membrane separation, electro-coagulation and chemical reduction are available to reduce the contamination of Cr(VI) in the effluent streams. These techniques are not eco-friendly and economically viable for the large volume of wastewater ireatment. Adsorption using low cost adsorbents is found to be (me of the cost effective technique for Cr(VI) removal from the effluent streams. In the present study, a waste biodegradable material, neem bark, is used. This neem bark is activated using concenirated sulphuric acid (98 wt%) and is used as an adsorbent for Cr(VI) removal from aqueous solutions. Batch adsorption experiments were conducted for determining the performance of activated neem bark for removal of Cr(VI). The effect of various important parameters such as effect of contact time, initial Cr(VI) concentration and dosage of adsorbent for the removal of Cr(VI) using activated neem bark adsorbent are studied. The kinetic studies show 70% removal of Cr(VI) using activated neem bark as an adsorbent while keeping 100 mg/L of initial Cr(VI) concentration The equilibrium data for the adsorption of Cr(VI) on activated neem bark is being tested with Langmuir isotherm model and Freundlich isotherm model. It is observed that it is following the Langmuir isotherm model and the corresponding adsorption capacity of activated neem bark is 26.95 mg/g. Pseudo first-order and second-order rate kinetic models are used to evaluate the mechanism of adsorption of Cr(VI) on activated neem bark It is observed that the adsorption of Cr(VI) on activated neon bark follows second order kinetics."
1578283,Tzou et al. 2002,Effect of organic complexing ligands on Cr(III) oxidation by MnOx,"Although Cr(III) is considered a Cr species with low mobility and toxicity, the potential oxidation of Cr(III) to Cr(VI) in soils containing Mn requires further scientific attention because of the acute toxicity of Cr(VI). This study evaluates the inhibition or enhancement of Cr(III) oxidation by Mn oxide in the presence of various organic ligands and concentrations. Batch experiments indicate that 200 muM of organic ligands inhibited 20 muM Cr(III) oxidation by Mn oxide at pH 4 because of the occurrence of reductive dissolution of Mn oxide. Although oxalate did not show strong inhibition of Cr(III) oxidation at pH 10, nevertheless, citrate and N-hydroxyethyl-ethylenediamine-triacetic acid (HEDTA) ligands did retard Cr(III) oxidation. It is possible that the co-precipitation of Cr(III) and organic ligand, which has a low dissociation constant, results in low release of Cr(III) and subsequent oxidation. The current results imply that the management of Cr(III)-containing waste is very important to prevent potential oxidation of Cr(III) by Mn oxides, particularly at low pH. However, the presence of organic ligands in the field may lead to low Cr(III) oxidation where Cr(III) waste is disposed.","Effect of organic complexing ligands on Cr(III) oxidation by MnOx Abs: Although Cr(III) is considered a Cr species with low mobility and toxicity, the potential oxidation of Cr(III) to Cr(VI) in soils containing Mn requires further scientific attention because of the acute toxicity of Cr(VI). This study evaluates the inhibition or enhancement of Cr(III) oxidation by Mn oxide in the presence of various organic ligands and concentrations. Batch experiments indicate that 200 muM of organic ligands inhibited 20 muM Cr(III) oxidation by Mn oxide at pH 4 because of the occurrence of reductive dissolution of Mn oxide. Although oxalate did not show strong inhibition of Cr(III) oxidation at pH 10, nevertheless, citrate and N-hydroxyethyl-ethylenediamine-triacetic acid (HEDTA) ligands did retard Cr(III) oxidation. It is possible that the co-precipitation of Cr(III) and organic ligand, which has a low dissociation constant, results in low release of Cr(III) and subsequent oxidation. The current results imply that the management of Cr(III)-containing waste is very important to prevent potential oxidation of Cr(III) by Mn oxides, particularly at low pH. However, the presence of organic ligands in the field may lead to low Cr(III) oxidation where Cr(III) waste is disposed."
1578282,Tzou et al. 1998,Chromate sorption by acidic and alkaline soils,"BIOSIS COPYRIGHT: BIOL ABS. The sorption and rate of reduction of chromium by acidic and alkaline soils was investigated. The results indicate that Cr(VI) sorbed more Cr in Ca(NO3)2, (0.01 M) electrolytes than in 0.001 M Ca(NO3)2 solution. Nonspecific anions influenced Cr(VI) sorbed by the Taoyuan acidic soils in the order: Cl- < ClO4- < SO42. On the other hand, in the alkaline Si-LO soils, these three electrolyte solutions showed slight difference in Cr(VI) sorption. In the experiment replacing phosphate by chromate in the Taoyuan acidic soils. the amount of chromate desorbed by phosphate increased with increasing Cr(VI) concentrations and decreased with increase in equilibration time. However, Cr(VI) desorption was not affected by equilibration time in the alkaline Si-Lo soils. When Cr(VI) was incubated at various soil water contents, sorption of Cr and reduction of Cr(VI) to Cr(III) was observed to increase with increasing incubation time. However, incubation in saturated water slowed dow","Chromate sorption by acidic and alkaline soils Abs: BIOSIS COPYRIGHT: BIOL ABS. The sorption and rate of reduction of chromium by acidic and alkaline soils was investigated. The results indicate that Cr(VI) sorbed more Cr in Ca(NO3)2, (0.01 M) electrolytes than in 0.001 M Ca(NO3)2 solution. Nonspecific anions influenced Cr(VI) sorbed by the Taoyuan acidic soils in the order: Cl- < ClO4- < SO42. On the other hand, in the alkaline Si-LO soils, these three electrolyte solutions showed slight difference in Cr(VI) sorption. In the experiment replacing phosphate by chromate in the Taoyuan acidic soils. the amount of chromate desorbed by phosphate increased with increasing Cr(VI) concentrations and decreased with increase in equilibration time. However, Cr(VI) desorption was not affected by equilibration time in the alkaline Si-Lo soils. When Cr(VI) was incubated at various soil water contents, sorption of Cr and reduction of Cr(VI) to Cr(III) was observed to increase with increasing incubation time. However, incubation in saturated water slowed dow"
1578281,Tirgar et al. 2011,Removal of airborne hexavalent chromium using alginate as a biosorbent,"Airborne hexavalent chromium has been classified as a human respiratory carcinogen and long term exposure has been known to cause ulceration and perforation of the nasal septum, bronchitis, asthma, and liver and kidney damage. Chromium electroplating plants are the major sources of atmospheric chromium and packed-bed scrubbers are the common control devices used to reduce emission of chromic acid mist from electroplating bathes. The feasibility of a new method to remove this pollutant using alginate beads as a biomass derivative was investigated by one factor at a time approach and Taguchi experimental design. Polluted air with different chromium mist concentrations (10-5000 mu g/m3) was contacted to alginate beads (3.3-20 g/L), floating in distilled water with adjusted pH (3-7), using an impinger at different temperatures (20 and 35oC), and various velocities (1.2 and 2.4 m/s). Although there were no statistical significant differences between factor levels, the higher ions removal efficiencies were achieved at lower levels of air velocities, pollution concentrations, higher levels of pHs, temperatures, and sorbent concentrations.","Removal of airborne hexavalent chromium using alginate as a biosorbent Abs: Airborne hexavalent chromium has been classified as a human respiratory carcinogen and long term exposure has been known to cause ulceration and perforation of the nasal septum, bronchitis, asthma, and liver and kidney damage. Chromium electroplating plants are the major sources of atmospheric chromium and packed-bed scrubbers are the common control devices used to reduce emission of chromic acid mist from electroplating bathes. The feasibility of a new method to remove this pollutant using alginate beads as a biomass derivative was investigated by one factor at a time approach and Taguchi experimental design. Polluted air with different chromium mist concentrations (10-5000 mu g/m3) was contacted to alginate beads (3.3-20 g/L), floating in distilled water with adjusted pH (3-7), using an impinger at different temperatures (20 and 35oC), and various velocities (1.2 and 2.4 m/s). Although there were no statistical significant differences between factor levels, the higher ions removal efficiencies were achieved at lower levels of air velocities, pollution concentrations, higher levels of pHs, temperatures, and sorbent concentrations."
1578280,Thomas et al. 1992,"AFTERCHROME DYEING OF WOOL .A. CHROMIUM IN THE EFFLUENT, ANALYTICAL DETERMINATION AND CHARACTERIZATION OF INFLUENCING FACTORS","As a consequence of increasing legal restrictions on the concentration of chromium in industrial discharges, afterchrome dyeing of wool has been re-evaluated. Special regard was given to the distribution of trivalent and hexavalent chromium species in the individual process stages (chroming, rinsing and ammonia aftertreatment baths) of afterchrome dyeing. Recommendations are outlined to give minimum chrome residues in the effluent and to avoid the distribution of the toxic hexavalent chromium species into the environment. The efficiency of the thiosulphate procedure is doubtful for improving the exhaustion of total chromium. Subsequent alkaline treatments of chrome-dyed wool lead to a desorption of chromium compounds that are probably fibre-bonded chromium-tetrathionate (sodium thiosulphate) complexes.","AFTERCHROME DYEING OF WOOL .A. CHROMIUM IN THE EFFLUENT, ANALYTICAL DETERMINATION AND CHARACTERIZATION OF INFLUENCING FACTORS Abs: As a consequence of increasing legal restrictions on the concentration of chromium in industrial discharges, afterchrome dyeing of wool has been re-evaluated. Special regard was given to the distribution of trivalent and hexavalent chromium species in the individual process stages (chroming, rinsing and ammonia aftertreatment baths) of afterchrome dyeing. Recommendations are outlined to give minimum chrome residues in the effluent and to avoid the distribution of the toxic hexavalent chromium species into the environment. The efficiency of the thiosulphate procedure is doubtful for improving the exhaustion of total chromium. Subsequent alkaline treatments of chrome-dyed wool lead to a desorption of chromium compounds that are probably fibre-bonded chromium-tetrathionate (sodium thiosulphate) complexes."
1578279,Thippeswamy et al. 2012,Bioaccumulation potential of Aspergillus niger and Aspergillus flavus for removal of heavy metals from paper mill effluent,"In the present study Aspergillus niger and Aspergillus flavus isolated from paper mill effluent showed tolerance and accumulation of toxic metals Ni, Zn, Cd, Pb, Cr and Cu from synthetic medium and paper mill effluent. Physico-chemical and heavy metals characterization of industrially treated paper mill effluent showed insignificant reduction in BOD, hardness, TDS and heavy metals as compared to permissible limits of BIS and WHO. A.niger and A.flavus were treated with synthetic medium containing 100-1000 mg l(-1) of six heavy metals. A.niger was able to tolerate and grow in 1000 mg l(-1) Pb, 500 mg l(-1) Cu, 250 mg l(-1) Zn and 100 mg l(-1) Cr, Ni respectively. No growth of An/get was observed in 100 mg l(-1) of Cd. A.flavus was capable to tolerate and grow in 1000 mg l(-1) Pb, Zn and Ni, 100 mg l(-1) Cu. A.flavus growth was completely inhibited in 100 mg l(-1) of Cd and Cr. The Cd, Zn, Cu and Pb reduction were found significant (p<0.05) in the paper effluent inoculated with A.niger and A.flavus biomass compared to industrial treated effluent. A.niger and A.flavus accumulated maximum of Pb (75.82%) followed by Zn(49.40%) > Cu (45.34%) > Ni (25.20%), while only 41% Cr was accumulated by A.niger from 100 mg l(-1) of Cr solution.","Bioaccumulation potential of Aspergillus niger and Aspergillus flavus for removal of heavy metals from paper mill effluent Abs: In the present study Aspergillus niger and Aspergillus flavus isolated from paper mill effluent showed tolerance and accumulation of toxic metals Ni, Zn, Cd, Pb, Cr and Cu from synthetic medium and paper mill effluent. Physico-chemical and heavy metals characterization of industrially treated paper mill effluent showed insignificant reduction in BOD, hardness, TDS and heavy metals as compared to permissible limits of BIS and WHO. A.niger and A.flavus were treated with synthetic medium containing 100-1000 mg l(-1) of six heavy metals. A.niger was able to tolerate and grow in 1000 mg l(-1) Pb, 500 mg l(-1) Cu, 250 mg l(-1) Zn and 100 mg l(-1) Cr, Ni respectively. No growth of An/get was observed in 100 mg l(-1) of Cd. A.flavus was capable to tolerate and grow in 1000 mg l(-1) Pb, Zn and Ni, 100 mg l(-1) Cu. A.flavus growth was completely inhibited in 100 mg l(-1) of Cd and Cr. The Cd, Zn, Cu and Pb reduction were found significant (p<0.05) in the paper effluent inoculated with A.niger and A.flavus biomass compared to industrial treated effluent. A.niger and A.flavus accumulated maximum of Pb (75.82%) followed by Zn(49.40%) > Cu (45.34%) > Ni (25.20%), while only 41% Cr was accumulated by A.niger from 100 mg l(-1) of Cr solution."
1578277,Tehrani et al. 2004,Chromium speciation by surfactant assisted solid-phase extraction and flame atomic absorption spectrometric detection,"A new procedure has been developed for chromium speciation in aqueous solution by the use of micellar, ion-association, solid-phase extraction techniques (SPE) followed by flame atomic absorption spectrometry. The method was based on the use of C-18 bonded phase silica SPE disks for retention of ion-associated Cr(VI) with cetyl trimethyl ammonium bromide (CTAB), elution of the retained species and subsequent detection by flame atomic absorption spectrometry (FAAS). Cr(III) was oxidized by potassium persulfate to Cr(VI), then the total chromium was retained on the disk and determined by FAAS. The amount of Cr(III) was calculated by the difference between the total and Cr(VI) values. The calculated limit of detections (LOD) (based on 3sigma) are 15 mug L(-1) and 20 mug L(-1) for Cr(VI) and Cr(III) respectively. No considerable interferences have been observed from other investigated anions and cations and the method has been successfully applied to water samples taken from the Karoon River in Khuzestan province.","Chromium speciation by surfactant assisted solid-phase extraction and flame atomic absorption spectrometric detection Abs: A new procedure has been developed for chromium speciation in aqueous solution by the use of micellar, ion-association, solid-phase extraction techniques (SPE) followed by flame atomic absorption spectrometry. The method was based on the use of C-18 bonded phase silica SPE disks for retention of ion-associated Cr(VI) with cetyl trimethyl ammonium bromide (CTAB), elution of the retained species and subsequent detection by flame atomic absorption spectrometry (FAAS). Cr(III) was oxidized by potassium persulfate to Cr(VI), then the total chromium was retained on the disk and determined by FAAS. The amount of Cr(III) was calculated by the difference between the total and Cr(VI) values. The calculated limit of detections (LOD) (based on 3sigma) are 15 mug L(-1) and 20 mug L(-1) for Cr(VI) and Cr(III) respectively. No considerable interferences have been observed from other investigated anions and cations and the method has been successfully applied to water samples taken from the Karoon River in Khuzestan province."
1578276,Tanriverdi and  Ozturk 2012,Use of Sodium Metabisulphide as An Alternative Depresant in Selective Flotation of Lead and Copper,"In this study, complex lead-zinc-copper ore located in the territory of Canakkale Province, Yenice County, Kalkim District has been worked on. Physical and mineralogical characteristics of the ore showed that the appropriate ore enrichment method is flotation. The first aim was to determine the optimum flotation conditions for the further studies. The flotation tests to determine the type of depressant were completed to use in selective flotation circuit of lead and copper. Potassium dichromate is widely used as a depressant of this type of ores. However, potassium dichromate is an undesirable chemical with carcinogen impacts and environmental drawbacks. Many alternatives of potassium dichromate is studied in recent years such as sodium metabisulphide. Sodium metabisulphide is less dangerous than potassium dichromate for environment and human health. In this study, the ore was beneficiated using sodium metabisulphide and 89.74 % cumulative recovery with 66.32 % Pb content in the final lead concentrate and 35.67 % cumulative recovery with 24.94 % Cu content in the final copper concentrate was obtained. The positive and negative aspects of sodium metabisulphide with respect to potassium dichromate are discussed regarding the experimental studies.","Use of Sodium Metabisulphide as An Alternative Depresant in Selective Flotation of Lead and Copper Abs: In this study, complex lead-zinc-copper ore located in the territory of Canakkale Province, Yenice County, Kalkim District has been worked on. Physical and mineralogical characteristics of the ore showed that the appropriate ore enrichment method is flotation. The first aim was to determine the optimum flotation conditions for the further studies. The flotation tests to determine the type of depressant were completed to use in selective flotation circuit of lead and copper. Potassium dichromate is widely used as a depressant of this type of ores. However, potassium dichromate is an undesirable chemical with carcinogen impacts and environmental drawbacks. Many alternatives of potassium dichromate is studied in recent years such as sodium metabisulphide. Sodium metabisulphide is less dangerous than potassium dichromate for environment and human health. In this study, the ore was beneficiated using sodium metabisulphide and 89.74 % cumulative recovery with 66.32 % Pb content in the final lead concentrate and 35.67 % cumulative recovery with 24.94 % Cu content in the final copper concentrate was obtained. The positive and negative aspects of sodium metabisulphide with respect to potassium dichromate are discussed regarding the experimental studies."
1578275,Tan et al. 1993,REMOVAL OF CHROMIUM(VI) FROM SOLUTION BY COCONUT HUSK AND PALM PRESSED FIBERS,"Removal of chromium(VI) from aqueous solutions by coconut husk fibres (CHF) and palm pressed fibres (PPF) was investigated using batch and column techniques. Batch tests showed that pH range for effective Cr(VI) removal was between 1.5 and 5 for CHF and between 1.5 and 3 for PPF. The adsorption capacities of CHF and PPF were estimated to be 29 and 14 mg Cr g-1 substrate at pH 2.0. In column studies, breakthrough curves of various columns containing PPF were obtained for various flow rates and bed-depths and the results were compared with Hutchin's model for adsorption column (1). The results of breakthrough curves of various columns containing mixed media of CHF or PPF in soil system demonstrated that both substrate could also be used as barriers in the landfill to maximize immobilization of toxic metal such as Cr(VI) in leachates.","REMOVAL OF CHROMIUM(VI) FROM SOLUTION BY COCONUT HUSK AND PALM PRESSED FIBERS Abs: Removal of chromium(VI) from aqueous solutions by coconut husk fibres (CHF) and palm pressed fibres (PPF) was investigated using batch and column techniques. Batch tests showed that pH range for effective Cr(VI) removal was between 1.5 and 5 for CHF and between 1.5 and 3 for PPF. The adsorption capacities of CHF and PPF were estimated to be 29 and 14 mg Cr g-1 substrate at pH 2.0. In column studies, breakthrough curves of various columns containing PPF were obtained for various flow rates and bed-depths and the results were compared with Hutchin's model for adsorption column (1). The results of breakthrough curves of various columns containing mixed media of CHF or PPF in soil system demonstrated that both substrate could also be used as barriers in the landfill to maximize immobilization of toxic metal such as Cr(VI) in leachates."
1578274,Swain and  Panigrahi 2001,Kinetics and mechanism of oxidation of hydroxylaminehydrochloride by vanadium (V) in the presence of sodium lauryl sulphate,Kinetics of oxidation of hydroxylaminehydrochloride in aqueous HClO4 medium has been studied at different temperatures both in the presence and absence of SLS. The kinetics shows first order dependence on both [NH2OH] and [V(V)] but change in ionic strength and [H+] have no effect on reaction rate. Decomposition of a precursor complex has been suggested as the slow step. The reaction is moderately catalysed by SLS and the catalysis has been rationalised by Menger and Portnoy model. Moderate binding constant value suggests that the precursor complex is bound to the micellar surface through hydrophilic binding. The kinetic data also fit into Piskziewicz model and conclusions drawn there from have limited significance.,Kinetics and mechanism of oxidation of hydroxylaminehydrochloride by vanadium (V) in the presence of sodium lauryl sulphate Abs: Kinetics of oxidation of hydroxylaminehydrochloride in aqueous HClO4 medium has been studied at different temperatures both in the presence and absence of SLS. The kinetics shows first order dependence on both [NH2OH] and [V(V)] but change in ionic strength and [H+] have no effect on reaction rate. Decomposition of a precursor complex has been suggested as the slow step. The reaction is moderately catalysed by SLS and the catalysis has been rationalised by Menger and Portnoy model. Moderate binding constant value suggests that the precursor complex is bound to the micellar surface through hydrophilic binding. The kinetic data also fit into Piskziewicz model and conclusions drawn there from have limited significance.
1578273,Subhajit et al. 2011,Biodegradation Kinetics of Cr (VI) by Acclimated Mixed Culture,"Chromium was discovered in 1797 by Vauquelin. Numerous industrial applications raised chromium to a very important economic element. At the same time, with the development of its uses, the adverse effects of chromium compounds in human health were being investigated. Both acute and chronic toxicity of chromium are mainly caused by hexavalent compounds. It is highly toxic in nature and causes adverse effects on human beings. The present study deals with the removal of hexavalent chromium compound from industrial waste water using biodegradation by an acclimated mixed culture developed from activated sludge. The biodegradation studies are conducted for an initial Cr(VI) concentration ranging from 10-50 mg/L. The enrichment of culture is carried out for a period of 7 days. In these experiments, 100 mL of minimum salt medium (MSM) is autoclaved and added with known amount of acclimated mixed culture obtained from the enrichment procedure. Known amount of Cr(VI) is added in autoclaved MSM to maintain the required concentration of Cr(VI). The flasks are kept in the rotary shaker which is maintained at 37 C and at 150 rpm throughout the biodegradation process. The samples are collected at different intervals. The obtained biomass growth is significant and indicate the considerable decrease in Cr(VI) concentration in the solution The biodegradation rate kinetic parameters are obtained for zero order and three and half order kinetic models.","Biodegradation Kinetics of Cr (VI) by Acclimated Mixed Culture Abs: Chromium was discovered in 1797 by Vauquelin. Numerous industrial applications raised chromium to a very important economic element. At the same time, with the development of its uses, the adverse effects of chromium compounds in human health were being investigated. Both acute and chronic toxicity of chromium are mainly caused by hexavalent compounds. It is highly toxic in nature and causes adverse effects on human beings. The present study deals with the removal of hexavalent chromium compound from industrial waste water using biodegradation by an acclimated mixed culture developed from activated sludge. The biodegradation studies are conducted for an initial Cr(VI) concentration ranging from 10-50 mg/L. The enrichment of culture is carried out for a period of 7 days. In these experiments, 100 mL of minimum salt medium (MSM) is autoclaved and added with known amount of acclimated mixed culture obtained from the enrichment procedure. Known amount of Cr(VI) is added in autoclaved MSM to maintain the required concentration of Cr(VI). The flasks are kept in the rotary shaker which is maintained at 37 C and at 150 rpm throughout the biodegradation process. The samples are collected at different intervals. The obtained biomass growth is significant and indicate the considerable decrease in Cr(VI) concentration in the solution The biodegradation rate kinetic parameters are obtained for zero order and three and half order kinetic models."
1578271,Sridevi and  Reddy 2000,"Effect of trivalent and hexavalent chromium on carbohydrate metabolism of a freshwater field crab, Barytelphusa guerini","The in vivo toxic impact of chromium in its two forms (trivalent and hexavalent) on glycogen metabolism in the tissues of freshwater field crab Barytelphusa guerini was studied. In a sublethal long-term exposure of 30, 60 and 90 days, the depletion of glycogen and glucose levels reflected in the activity of glycogenphosphorylases 'a' and 'ab'. A tissue specific and time-dependent variation in tissue glucose reserves parelleled the progressive accumulation of haemolymph sugars. Trivalent and hexavalent chromium induced alterations in metabolite levels and in enzyme activities in the tissues. The magnitude of responses were found more in the hexavalent form than in trivalent form.","Effect of trivalent and hexavalent chromium on carbohydrate metabolism of a freshwater field crab, Barytelphusa guerini Abs: The in vivo toxic impact of chromium in its two forms (trivalent and hexavalent) on glycogen metabolism in the tissues of freshwater field crab Barytelphusa guerini was studied. In a sublethal long-term exposure of 30, 60 and 90 days, the depletion of glycogen and glucose levels reflected in the activity of glycogenphosphorylases 'a' and 'ab'. A tissue specific and time-dependent variation in tissue glucose reserves parelleled the progressive accumulation of haemolymph sugars. Trivalent and hexavalent chromium induced alterations in metabolite levels and in enzyme activities in the tissues. The magnitude of responses were found more in the hexavalent form than in trivalent form."
1578270,Soomro et al. 2011,Simple and rapid spectrophotometric determination of trace level chromium using bis (salicylaldehyde) orthophenylenediamine in nonionic micellar media,"Bis(salicylaldehyde)orthophenylenediamine (BSOPD) has been proposed as new analytical reagent for the direct spectrophotometric determination of chromium. It reacts with chromium(VI) in slightly acidic (0.1 - 0.3 M H2SO4) micellar medium to form a yellow - orange chelate with a molar ratio 2:3. The most remarkable point of this method is that the molar absorptivities of the Cr-VI - BSOPD complex formed in the presence of nonionic TritonX - 100 surfactant are almost 10 times higher than the value observed in aqueous solution. This results in enhancing the sensitivity and selectivity of the method. The reaction is instantaneous and the maximum absorbance was obtained at 482 nm and remains constant for over 24h. The average molar absorption coefficient and Sandell's sensitivity were found 3.5 x 10(5) L mol(-1) cm(-2) and 5 ng cm(-2) of Cr(VI), respectively. Linear calibration graphs were obtained for 0.01 - 12.0 mgL(-1) of Cr(VI) with correlation coefficient value 0.9987 for Cr - BSOPD complex. Large excess of over 50 cations, anions and complexing agents do not interfere in the determination. The method was successfully used in the determination of chromium(VI) from synthetic mixture and certified reference materials to test the validity of the method and the results of analyses were found to be in excellent agreement with those of certified values. The developed method was also used for the determination of chromium in some environmental waters (potable and polluted), biological samples (blood and urine) and to determine chromium species. The results of the biological analyses by the proposed method were in good agreement with those of by AAS.","Simple and rapid spectrophotometric determination of trace level chromium using bis (salicylaldehyde) orthophenylenediamine in nonionic micellar media Abs: Bis(salicylaldehyde)orthophenylenediamine (BSOPD) has been proposed as new analytical reagent for the direct spectrophotometric determination of chromium. It reacts with chromium(VI) in slightly acidic (0.1 - 0.3 M H2SO4) micellar medium to form a yellow - orange chelate with a molar ratio 2:3. The most remarkable point of this method is that the molar absorptivities of the Cr-VI - BSOPD complex formed in the presence of nonionic TritonX - 100 surfactant are almost 10 times higher than the value observed in aqueous solution. This results in enhancing the sensitivity and selectivity of the method. The reaction is instantaneous and the maximum absorbance was obtained at 482 nm and remains constant for over 24h. The average molar absorption coefficient and Sandell's sensitivity were found 3.5 x 10(5) L mol(-1) cm(-2) and 5 ng cm(-2) of Cr(VI), respectively. Linear calibration graphs were obtained for 0.01 - 12.0 mgL(-1) of Cr(VI) with correlation coefficient value 0.9987 for Cr - BSOPD complex. Large excess of over 50 cations, anions and complexing agents do not interfere in the determination. The method was successfully used in the determination of chromium(VI) from synthetic mixture and certified reference materials to test the validity of the method and the results of analyses were found to be in excellent agreement with those of certified values. The developed method was also used for the determination of chromium in some environmental waters (potable and polluted), biological samples (blood and urine) and to determine chromium species. The results of the biological analyses by the proposed method were in good agreement with those of by AAS."
1578269,Sivaprakash et al. 2009,KINETICS AND EQUILIBRIUM STUDIES ON THE BIOSORPTION OF HEXAVALENT CHROMIUM FROM AQUEOUS SOLUTIONS USING BACILLUS SUBTILIS BIOMASS,"Heavy metal contamination of industrial effluents is one of the significant environmental problems due to their toxic nature and accumulation throughout the food chain as non-biodegradable pollutants. In this study, dead Bacillus subtilis biomass was assessed for its efficiency to remove chromium(VI) from aqueous solutions. Optimum pH and temperature for biosorption of Cr(VI) were found to be 2.0 and 30oC, respectively. The biomass has the maximum biosorption capacity of 14.54 mg/g of biomass at 100 ppm initial chromium concentration and 2 g/l biomass loading. The biosorption process followed pseudo first order kinetic model, implying that the initial rate of biosorption is totally independent of the initial concentration. The biosorption of Cr(VI) is well described by Langmuir isotherm, which express the existence of monolayer adsorption under the experimental conditions. The adsorption-desorption experiments performed inferred the reusability of the biomass. X-ray photoelectron spectroscopy studies revealed that chromium bound on to the B. subtilis biomass was in trivalent form.","KINETICS AND EQUILIBRIUM STUDIES ON THE BIOSORPTION OF HEXAVALENT CHROMIUM FROM AQUEOUS SOLUTIONS USING BACILLUS SUBTILIS BIOMASS Abs: Heavy metal contamination of industrial effluents is one of the significant environmental problems due to their toxic nature and accumulation throughout the food chain as non-biodegradable pollutants. In this study, dead Bacillus subtilis biomass was assessed for its efficiency to remove chromium(VI) from aqueous solutions. Optimum pH and temperature for biosorption of Cr(VI) were found to be 2.0 and 30oC, respectively. The biomass has the maximum biosorption capacity of 14.54 mg/g of biomass at 100 ppm initial chromium concentration and 2 g/l biomass loading. The biosorption process followed pseudo first order kinetic model, implying that the initial rate of biosorption is totally independent of the initial concentration. The biosorption of Cr(VI) is well described by Langmuir isotherm, which express the existence of monolayer adsorption under the experimental conditions. The adsorption-desorption experiments performed inferred the reusability of the biomass. X-ray photoelectron spectroscopy studies revealed that chromium bound on to the B. subtilis biomass was in trivalent form."
1578268,Singh and  Singh 2012,Treatment of Water Containg Chromium (VI) Using Rice Husk Carbon As a Newlow Cost Adsorbent,"Presence of heavy metals in the aquatic systems has become a serious problem. As a result, there has been a great deal of attention given to new technologies for removal of heavy metal ions from contaminated waters. Adsorption is one of the effective methods for removal of toxic heavy metal such as chromium (VI). In the present study, adsorbent is prepared from rice husk, a low cost by product from a rice mill. The rice husk carbon is activated using H3PO4 (40%). The stock solution of Cr (VI) is prepared by dissolving 2.828 gm of potassium dichromate (Central Drug House (CDH), India) in 1 litre of demineralized water. Batch mode experiments are done. The effect of various parameters like adsorbent dose, pH and contact time are studied. The studies demonstrate that the Rice Husk Carbon (RHC) has a significant capacity for adsorption of Cr (VI) from aqueous solution. The RHC characteristics are reported as FTIR and other physical properties are tabulated average. The break through capacity for Cr (VI) (100 mg/l, pH 2) is on average 38.1 mg/g. The adsorption of chromium (VI) was found to be maximum(93-94%) at low values of pH (around 2) for the carbon dosage of 1000mg/L, and nearly 100% for carbon dosage of 1200mg/L. RHC exhibits high degree of selectivity for Cr (VI) adsorption. The adsorbent prepared from rice husk carbon is efficient and it is proposed that it can be conveniently employed as a low cost alternative in the treatment of industrial waste water.","Treatment of Water Containg Chromium (VI) Using Rice Husk Carbon As a Newlow Cost Adsorbent Abs: Presence of heavy metals in the aquatic systems has become a serious problem. As a result, there has been a great deal of attention given to new technologies for removal of heavy metal ions from contaminated waters. Adsorption is one of the effective methods for removal of toxic heavy metal such as chromium (VI). In the present study, adsorbent is prepared from rice husk, a low cost by product from a rice mill. The rice husk carbon is activated using H3PO4 (40%). The stock solution of Cr (VI) is prepared by dissolving 2.828 gm of potassium dichromate (Central Drug House (CDH), India) in 1 litre of demineralized water. Batch mode experiments are done. The effect of various parameters like adsorbent dose, pH and contact time are studied. The studies demonstrate that the Rice Husk Carbon (RHC) has a significant capacity for adsorption of Cr (VI) from aqueous solution. The RHC characteristics are reported as FTIR and other physical properties are tabulated average. The break through capacity for Cr (VI) (100 mg/l, pH 2) is on average 38.1 mg/g. The adsorption of chromium (VI) was found to be maximum(93-94%) at low values of pH (around 2) for the carbon dosage of 1000mg/L, and nearly 100% for carbon dosage of 1200mg/L. RHC exhibits high degree of selectivity for Cr (VI) adsorption. The adsorbent prepared from rice husk carbon is efficient and it is proposed that it can be conveniently employed as a low cost alternative in the treatment of industrial waste water."
1578267,Singh and  Singh 2001,Hexavalent chromium removal using iron bearing industrial sludges,"The use of iron bearing metallic and mineral materials for the treatment of highly toxic Cr(VI) containing industrial wastewater have received increased attention for the past decade. In conventional treatment, a large amount of chromium hydroxide generates as secondary solid waste which poses a serious problem of disposal. In the presence of iron bearing materials, Cr(VI) reduces to Cr(III) and Fe(II) oxidises to Fe(III) generating mixed complexes from which separation probability of individual element reduces. Based on this chemical principle it is expected that such industrial solid wastes containing iron as a major constituent have potential to reduce highly toxic Cr(VI) to less toxic Cr(III). In view of this, present investigation was aimed to utilise iron bearing industrial wastes like sludges of steel tube making industry and aluminium industry for removal of Cr(VI). Studies include identification of suitable pH for the Cr(VI) reduction, optimisation of dosage and contact time and determination of reaction kinetics. No Cr(VI) was detected from the reacted wastes and total chromium was measured as Cr(III). Toxicity characteristics leaching procedure(TCLP) has been employed to estimate the leachability of chromium, iron etc from the reacted wastes. TCLP results indicate a negligible amount of chromium as Cr(III) and iron leachability from the reacted wastes.","Hexavalent chromium removal using iron bearing industrial sludges Abs: The use of iron bearing metallic and mineral materials for the treatment of highly toxic Cr(VI) containing industrial wastewater have received increased attention for the past decade. In conventional treatment, a large amount of chromium hydroxide generates as secondary solid waste which poses a serious problem of disposal. In the presence of iron bearing materials, Cr(VI) reduces to Cr(III) and Fe(II) oxidises to Fe(III) generating mixed complexes from which separation probability of individual element reduces. Based on this chemical principle it is expected that such industrial solid wastes containing iron as a major constituent have potential to reduce highly toxic Cr(VI) to less toxic Cr(III). In view of this, present investigation was aimed to utilise iron bearing industrial wastes like sludges of steel tube making industry and aluminium industry for removal of Cr(VI). Studies include identification of suitable pH for the Cr(VI) reduction, optimisation of dosage and contact time and determination of reaction kinetics. No Cr(VI) was detected from the reacted wastes and total chromium was measured as Cr(III). Toxicity characteristics leaching procedure(TCLP) has been employed to estimate the leachability of chromium, iron etc from the reacted wastes. TCLP results indicate a negligible amount of chromium as Cr(III) and iron leachability from the reacted wastes."
1578266,Singh et al. 1993,The use of hematite for chromium(VI) removal,"BIOSIS COPYRIGHT: BIOL ABS. The ability of hematite to remove Cr(VI) from aqueous solutions has been studied at different concentrations, temperatures and pH. The maximum removal (97%) was observed at 40êC and pH 2.7 with initial concentrations of 19.23 mumol Cr(VI) and 40 g/L hematite. The equilibrium data obey the Langmuir isotherm for the present system. The reaction dynamics have been studied and the process involves both film and pore diffusion to different extents. Mass transfer and diffusion coefficients have been determined. Thermodynamic parameters indicate the spontaneous and endothermic nature of the process. The uptake of Cr(VI) increases as pH decreases and the maximum removal has been attributed to the formation of positively charged aquacomplexes of iron at the surface and a subsequent interaction with the dominant HCrO4- species. An empirical equation has been developed to predict equilibrium adsorption capacity from knowledge of equilibrium adsorbate concentration.","The use of hematite for chromium(VI) removal Abs: BIOSIS COPYRIGHT: BIOL ABS. The ability of hematite to remove Cr(VI) from aqueous solutions has been studied at different concentrations, temperatures and pH. The maximum removal (97%) was observed at 40êC and pH 2.7 with initial concentrations of 19.23 mumol Cr(VI) and 40 g/L hematite. The equilibrium data obey the Langmuir isotherm for the present system. The reaction dynamics have been studied and the process involves both film and pore diffusion to different extents. Mass transfer and diffusion coefficients have been determined. Thermodynamic parameters indicate the spontaneous and endothermic nature of the process. The uptake of Cr(VI) increases as pH decreases and the maximum removal has been attributed to the formation of positively charged aquacomplexes of iron at the surface and a subsequent interaction with the dominant HCrO4- species. An empirical equation has been developed to predict equilibrium adsorption capacity from knowledge of equilibrium adsorbate concentration."
1578265,Sindhu et al. 2012,A comparative study of surface modification in carbonized rice husk by acid treatment,"Water pollution by heavy metals is a major environmental problem because of their toxicity and its removal is highly essential. In this present investigation, two types of adsorbents were prepared viz. activated carbon from acid treated rice husk (ACARH) and activated carbon from rice husk followed by acid treatment (ACRHA). Characterization of the adsorbents was performed by BET analyzer, Fourier transform infrared spectroscopy (FTIR), scanning electron microscopy (SEM) and EDAX analysis to determine their surface area and morphological behavior. Adsorption studies were conducted to optimize the process variables such as initial metal ion concentration, adsorbent dosage, pH of the solution and temperature on the percentage removal of hexavalent Cr ions from aqueous solution. It is found that ACARH adsorbent is highly effective for the removal of metal ions than ACRHA. Various kinetic and isotherm models were fitted with the experimental data obtained from ACARH adsorbent to evaluate the solute interaction behavior.","A comparative study of surface modification in carbonized rice husk by acid treatment Abs: Water pollution by heavy metals is a major environmental problem because of their toxicity and its removal is highly essential. In this present investigation, two types of adsorbents were prepared viz. activated carbon from acid treated rice husk (ACARH) and activated carbon from rice husk followed by acid treatment (ACRHA). Characterization of the adsorbents was performed by BET analyzer, Fourier transform infrared spectroscopy (FTIR), scanning electron microscopy (SEM) and EDAX analysis to determine their surface area and morphological behavior. Adsorption studies were conducted to optimize the process variables such as initial metal ion concentration, adsorbent dosage, pH of the solution and temperature on the percentage removal of hexavalent Cr ions from aqueous solution. It is found that ACARH adsorbent is highly effective for the removal of metal ions than ACRHA. Various kinetic and isotherm models were fitted with the experimental data obtained from ACARH adsorbent to evaluate the solute interaction behavior."
1578264,Shukla and  Upadhyay 2008,Brij-35 micellar catalysed chloramine-T oxidation of vitamins: A kinetic study,"The kinetics of oxidation of the vitamins (131 and 136) by sodium salt of p-toluene sulfonamide (Chloramine-T) have been studied in presence of a non-ionic surfactant, i.e., polyoxyethylene(23)laurylether (Brij-35) in perchloric acid medium. Catalytic effect of Brij-35 micelle has been observed on the rate of-oxidation. The reactions show first order, fractional order and zero-order dependence of rate with respect to chloramine-T,. vitamins and HClO4, respectively. The mechanism in absence as well as in presence of surfactant has been proposed. The spectrophotometric evidence supports the binding/association between chloramine-T and Brij-35 micelle. The kinetic data have also been rationalised in terms of Menger and Portnoy's kinetic model and binding parameters have been evaluated.","Brij-35 micellar catalysed chloramine-T oxidation of vitamins: A kinetic study Abs: The kinetics of oxidation of the vitamins (131 and 136) by sodium salt of p-toluene sulfonamide (Chloramine-T) have been studied in presence of a non-ionic surfactant, i.e., polyoxyethylene(23)laurylether (Brij-35) in perchloric acid medium. Catalytic effect of Brij-35 micelle has been observed on the rate of-oxidation. The reactions show first order, fractional order and zero-order dependence of rate with respect to chloramine-T,. vitamins and HClO4, respectively. The mechanism in absence as well as in presence of surfactant has been proposed. The spectrophotometric evidence supports the binding/association between chloramine-T and Brij-35 micelle. The kinetic data have also been rationalised in terms of Menger and Portnoy's kinetic model and binding parameters have been evaluated."
1578262,Shilcrat et al. 1991,"SYNTHESIS, X-RAY CRYSTAL-STRUCTURE DETERMINATION AND ANTIINFLAMMATORY ACTIVITY OF THE REGIOISOMERS - 5-PHENYL-6-(4-PYRIDYL)-2,3-DIHYDROIMIDAZO 2,1-B THIAZOLE AND 6-PHENYL-5-(4-PYRIDYL)-2,3-DIHYDROIMIDAZO 2,1-B THIAZOLE - A STRUCTURAL REASSIGNMENT","A regiospecific synthesis of 6-phenyl-5-(4-pyridyl)-2,3-dihydroimidazo[2,1-b]thiazole (2) was accomplished by treatment of 6-phenyl-2,3-dihydroimidazo[2,1-b]thiazole (10) with the reactive complex of pyridine and ethyl chloroformate followed by oxidation with chromium(VI) oxide. Reaction of 4-phenyl-5-(4-pyridyl)imidazole-2-thione (12) with 1,2-dibromoethane in the presence of base also gave 2 together with its regioisomer 3. The structures of 2 and 3 were confirmed by X-ray crystallography. Evaluation, on oral administration, in a one hour arachidonic acid-induced mouse ear inflammation assay, showed the inhibition of edema by 2 (48%) and 3 (34%) to be less than that of the 6-(4-fluorophenyl) analog 1 (SK&/F 86002) (69%), a known antiinflammatory agent.","SYNTHESIS, X-RAY CRYSTAL-STRUCTURE DETERMINATION AND ANTIINFLAMMATORY ACTIVITY OF THE REGIOISOMERS - 5-PHENYL-6-(4-PYRIDYL)-2,3-DIHYDROIMIDAZO 2,1-B THIAZOLE AND 6-PHENYL-5-(4-PYRIDYL)-2,3-DIHYDROIMIDAZO 2,1-B THIAZOLE - A STRUCTURAL REASSIGNMENT Abs: A regiospecific synthesis of 6-phenyl-5-(4-pyridyl)-2,3-dihydroimidazo[2,1-b]thiazole (2) was accomplished by treatment of 6-phenyl-2,3-dihydroimidazo[2,1-b]thiazole (10) with the reactive complex of pyridine and ethyl chloroformate followed by oxidation with chromium(VI) oxide. Reaction of 4-phenyl-5-(4-pyridyl)imidazole-2-thione (12) with 1,2-dibromoethane in the presence of base also gave 2 together with its regioisomer 3. The structures of 2 and 3 were confirmed by X-ray crystallography. Evaluation, on oral administration, in a one hour arachidonic acid-induced mouse ear inflammation assay, showed the inhibition of edema by 2 (48%) and 3 (34%) to be less than that of the 6-(4-fluorophenyl) analog 1 (SK&/F 86002) (69%), a known antiinflammatory agent."
1578261,Shemirani et al. 2004,The application of cloud point extraction for the preconcentration and speciation of chromium by Flame Atomic Absorption Spectrometry,"This paper outlines a method for the analysis of the oxidation states of Cr employing a suitable chelating agent and the cloud point phenomenon for Cr(III) and total Cr analysis. The method involves preconcentration of metal chelates followed by flame atomic absorption spectrometric analysis. We use Schiff base(N,N'-bis-(alpha-methyl salicylidene) propane-1, 3-diimine) as a chelating agent for cloud point extraction for the first time. Cr(III) reacts with chelating agent for the formation of a hydrophobic complex, which is subsequently entrapped in the surfactant micelles. The Cr(VI) assay is based on its reduction to Cr(III) by the addition of concentrated H,SO 4 and ethanol to the sample solution; Cr(III) subsequently reacts with chelating agent in a similar manner The condensed surfactant phase with the metal chelate is introduced into a flame atomic absorption spectrometer, whereby discrimination of Cr species is feasible by calculating the Cr(VI) Concentration from the difference between total Cr and Cr(III). After optimization of the complexation and extraction conditions, a good enrichment factor was obtained. The analytical curves were rectilinear up to 75 mug L(-1) and the relative standard deviations were 2.3% for both species. The limits of detection are sufficiently low and lie around 0.1 mug L(-1). The proposed method was applied successfully to the determination of Cr(III) and Cr(VI) in tap water and river water samples. The method was validated by the analysis of certified reference material BCR 544 for both species.","The application of cloud point extraction for the preconcentration and speciation of chromium by Flame Atomic Absorption Spectrometry Abs: This paper outlines a method for the analysis of the oxidation states of Cr employing a suitable chelating agent and the cloud point phenomenon for Cr(III) and total Cr analysis. The method involves preconcentration of metal chelates followed by flame atomic absorption spectrometric analysis. We use Schiff base(N,N'-bis-(alpha-methyl salicylidene) propane-1, 3-diimine) as a chelating agent for cloud point extraction for the first time. Cr(III) reacts with chelating agent for the formation of a hydrophobic complex, which is subsequently entrapped in the surfactant micelles. The Cr(VI) assay is based on its reduction to Cr(III) by the addition of concentrated H,SO 4 and ethanol to the sample solution; Cr(III) subsequently reacts with chelating agent in a similar manner The condensed surfactant phase with the metal chelate is introduced into a flame atomic absorption spectrometer, whereby discrimination of Cr species is feasible by calculating the Cr(VI) Concentration from the difference between total Cr and Cr(III). After optimization of the complexation and extraction conditions, a good enrichment factor was obtained. The analytical curves were rectilinear up to 75 mug L(-1) and the relative standard deviations were 2.3% for both species. The limits of detection are sufficiently low and lie around 0.1 mug L(-1). The proposed method was applied successfully to the determination of Cr(III) and Cr(VI) in tap water and river water samples. The method was validated by the analysis of certified reference material BCR 544 for both species."
1578260,Shah et al. 2000,"Determination of physico-chemical properties and heavy metals in the effluents of match industries of Hayat Abad Industrial Estate, NWFP","Effluent samples were collected at different intervals from match industries located at Hayat Abad Industrial Estate. These samples were analyzed for their physico-chemical properties and selected toxic metals suspected to be released by match industries. The effluents of all match industries contained high concentration than the permissible level of chromium (VI), iron and manganese ranging from 11.00 +/- 0.00- 38.91 +/- 0.05 ppm, 11.76 +/-0.10-21.70 +/- .08 and 0.06 +/-0.01-2.28 +/-0.09 respectively. Other heavy metals like copper, lead, zinc and nickel were founded to be below detection limit.","Determination of physico-chemical properties and heavy metals in the effluents of match industries of Hayat Abad Industrial Estate, NWFP Abs: Effluent samples were collected at different intervals from match industries located at Hayat Abad Industrial Estate. These samples were analyzed for their physico-chemical properties and selected toxic metals suspected to be released by match industries. The effluents of all match industries contained high concentration than the permissible level of chromium (VI), iron and manganese ranging from 11.00 +/- 0.00- 38.91 +/- 0.05 ppm, 11.76 +/-0.10-21.70 +/- .08 and 0.06 +/-0.01-2.28 +/-0.09 respectively. Other heavy metals like copper, lead, zinc and nickel were founded to be below detection limit."
1578258,Schwarzenbach et al. 1997,Reductive transformations of anthropogenic chemicals in natural and technical systems,"Reductive transformation reactions of chemical pollutants (e.g., polyhalogenated hydrocarbons, aromatic azo and nitro compounds, chromium(VI) species) in the environment are important both from an ecotoxicological and from an environmental technology point of view. Using well-defined model reactors as well as more complex 'real world' systems, several groups at EAWAG are trying to unravel compound-and system-specific factors that control the reduction of a variety of anthropogenic chemicals under different conditions in the environment. The examples presented in this article include the reduction of nitroaromatic compounds under iron- and sulfate-reducing conditions, the reductive dehalogenation of chlorinated ethenes by cob(I)alamin and by a bacterium that uses such compounds as terminal electron accepters, and the reduction of chromium(VI) by various reduced iron species. The link between microbial and abiotic (chemical) processes involved in reductive transformations of pollutants is emphasized. The major goal of this article is to illustrate the approaches taken to elucidate the mechanisms and kinetics of environmentally relevant reduction reactions of pollutants, and to discuss how the results of such studies can be used 1) to gain insight into what is actually happening in the environment, and 2) to develop methods for the treatment of chemical wastes or contaminated sites.","Reductive transformations of anthropogenic chemicals in natural and technical systems Abs: Reductive transformation reactions of chemical pollutants (e.g., polyhalogenated hydrocarbons, aromatic azo and nitro compounds, chromium(VI) species) in the environment are important both from an ecotoxicological and from an environmental technology point of view. Using well-defined model reactors as well as more complex 'real world' systems, several groups at EAWAG are trying to unravel compound-and system-specific factors that control the reduction of a variety of anthropogenic chemicals under different conditions in the environment. The examples presented in this article include the reduction of nitroaromatic compounds under iron- and sulfate-reducing conditions, the reductive dehalogenation of chlorinated ethenes by cob(I)alamin and by a bacterium that uses such compounds as terminal electron accepters, and the reduction of chromium(VI) by various reduced iron species. The link between microbial and abiotic (chemical) processes involved in reductive transformations of pollutants is emphasized. The major goal of this article is to illustrate the approaches taken to elucidate the mechanisms and kinetics of environmentally relevant reduction reactions of pollutants, and to discuss how the results of such studies can be used 1) to gain insight into what is actually happening in the environment, and 2) to develop methods for the treatment of chemical wastes or contaminated sites."
1578257,Sarkar et al. 1996,Protection afforded by crude spinach beet leaf extract and equivalent amounts of chlorophyll and chlorophyllin against clastogenic effects of potassium dichromate in mice in vivo,"The comparative efficacy of crude extract of spinach-beet leaves (Beta vulgaris vat. benghalensis Hort. Chenopodiaceae) and equivalent amounts of chlorophyll and chlorophyllin in reducing clastogenic activity of a hexavalent chromium compound, potassium dichromate (K2Cr2O7), was tested in mouse bone marrow cells in vivo. The endpoints monitored were chromosomal aberrations (CA). Mice were fed the crude leaf extract by gavage for 7 consecutive clays and then treated with the metallic salt on day 7. In separate sets, chlorophyll extracted from the spinach-beet leaves and a synthetic compound chlorophyllin were administered simultaneously with, before, or after exposure to the chromium compound. Chromosomes were studied from bone marrow cells 24 h after the treatment. Crude leaf extract and chlorophyllin did not induce chromosomal aberrations when given alone. Priming,vith the crude extract reduced the clastogenic effects of potassium dichromate to the control level. Similar protection was afforded by chlorophyllin when given simultaneously. Chlorophyll, on the other hand, induced significantly higher number of chromosomal aberrations when given alone as compared to distilled water and did not reduce the clastogenic activity of the metal when administered in combination.","Protection afforded by crude spinach beet leaf extract and equivalent amounts of chlorophyll and chlorophyllin against clastogenic effects of potassium dichromate in mice in vivo Abs: The comparative efficacy of crude extract of spinach-beet leaves (Beta vulgaris vat. benghalensis Hort. Chenopodiaceae) and equivalent amounts of chlorophyll and chlorophyllin in reducing clastogenic activity of a hexavalent chromium compound, potassium dichromate (K2Cr2O7), was tested in mouse bone marrow cells in vivo. The endpoints monitored were chromosomal aberrations (CA). Mice were fed the crude leaf extract by gavage for 7 consecutive clays and then treated with the metallic salt on day 7. In separate sets, chlorophyll extracted from the spinach-beet leaves and a synthetic compound chlorophyllin were administered simultaneously with, before, or after exposure to the chromium compound. Chromosomes were studied from bone marrow cells 24 h after the treatment. Crude leaf extract and chlorophyllin did not induce chromosomal aberrations when given alone. Priming,vith the crude extract reduced the clastogenic effects of potassium dichromate to the control level. Similar protection was afforded by chlorophyllin when given simultaneously. Chlorophyll, on the other hand, induced significantly higher number of chromosomal aberrations when given alone as compared to distilled water and did not reduce the clastogenic activity of the metal when administered in combination."
1578256,Sarada and  Reddy 1993,EFFECT OF SURFACTANTS ON OXALIC-ACID CATALYZED OXIDATION OF AROMATIC AZO-COMPOUNDS BY CHROMIUM(VI),"Effect of surfactants of different charge type on the rate of oxalic acid catalysed oxidation of p-SO3H, c-COOH, p-COOH and p-Cl benzene azodimethylaniline (BADMA) by Cr(VI) in 10% acetic acid medium has been investigated. Sodium dodecyl sulphate (SDS) and cetlytrimethylammonium bromide (CTAB) inhibited while polyoxyethylene(23) dodecanol (Brij-35) catalysed the reactions. 10(-2) M SDS and CTAB) inhibited the oxidation of p-SO3H, o-COOH, p-COOH and p-Cl BADMA Catalytic effect of 10(-2) M Brij 35 has been investigated. These effects are discussed on the basis of interactions of the above aromatic azo compounds with the micelles of different charge type. Binding parameters have been calculated by analysing the data using a model suggested by Piszkiewicz. Influence of surfactants on the activation parameters of the reactions have been discussed.","EFFECT OF SURFACTANTS ON OXALIC-ACID CATALYZED OXIDATION OF AROMATIC AZO-COMPOUNDS BY CHROMIUM(VI) Abs: Effect of surfactants of different charge type on the rate of oxalic acid catalysed oxidation of p-SO3H, c-COOH, p-COOH and p-Cl benzene azodimethylaniline (BADMA) by Cr(VI) in 10% acetic acid medium has been investigated. Sodium dodecyl sulphate (SDS) and cetlytrimethylammonium bromide (CTAB) inhibited while polyoxyethylene(23) dodecanol (Brij-35) catalysed the reactions. 10(-2) M SDS and CTAB) inhibited the oxidation of p-SO3H, o-COOH, p-COOH and p-Cl BADMA Catalytic effect of 10(-2) M Brij 35 has been investigated. These effects are discussed on the basis of interactions of the above aromatic azo compounds with the micelles of different charge type. Binding parameters have been calculated by analysing the data using a model suggested by Piszkiewicz. Influence of surfactants on the activation parameters of the reactions have been discussed."
1578255,Sankararaj et al. 1995,MICELLAR CATALYSIS ON THE REDOX REACTIONS OF DIALKYL SULFIDES WITH CHROMIUM(VI),"Chromium(VI) oxidation of diethyl sulphide (DES), diisopropylsulphide(DPS), di-n-butyl sulphide (DBS) and di-t-butyl sulphide (DTBS) in 99% acetonitrile-1% water(v/v) follows second order kinetics, first order in each reactant. A mechanism involving the rate determining nucleophilic attack of sulphide on Cr of H2CrO4 followed by fast ligand coupling between O- and S+ to form sulphoxide as the product has been formulated. The anionic surfactant, sodium dodecyl sulphate, catalyses and the cationic surfactant, cetyltrimethylammonium chloride, inhibits the rate of oxidation which is explained by the proposal that the reaction takes place both in aqueous and micellar phases. The catalytic role. of H+ and development of positive charge on sulphur due to the electron transfer from sulphide to Cr(VI) favour the reaction in the anionic micelle and disfavour in the cationic micelle.","MICELLAR CATALYSIS ON THE REDOX REACTIONS OF DIALKYL SULFIDES WITH CHROMIUM(VI) Abs: Chromium(VI) oxidation of diethyl sulphide (DES), diisopropylsulphide(DPS), di-n-butyl sulphide (DBS) and di-t-butyl sulphide (DTBS) in 99% acetonitrile-1% water(v/v) follows second order kinetics, first order in each reactant. A mechanism involving the rate determining nucleophilic attack of sulphide on Cr of H2CrO4 followed by fast ligand coupling between O- and S+ to form sulphoxide as the product has been formulated. The anionic surfactant, sodium dodecyl sulphate, catalyses and the cationic surfactant, cetyltrimethylammonium chloride, inhibits the rate of oxidation which is explained by the proposal that the reaction takes place both in aqueous and micellar phases. The catalytic role. of H+ and development of positive charge on sulphur due to the electron transfer from sulphide to Cr(VI) favour the reaction in the anionic micelle and disfavour in the cationic micelle."
1578254,Sahu and  Panigrahi 1996,Micellar catalysis - Effect of sodium lauryl sulphate in the oxidation of cyclopentanol by chromic acid,"Cyclopentanol oxidation by Cr-IV in presence and absence of sodium lauryl sulphate (NaLS) is first order in both the reactants. However, the acid dependence changes from a mixed order in absence of NaLS to pure second order in presence of NaLS. The oxidation rate decreases monotonically with [NaLS] above critical micellar concentration. The observation has been rationalised in the light of both Menger-Portnoy model as well as Berezin's model. One of the reactants, viz. Cr-VI is partitioned between the micellar and aqueous phase.","Micellar catalysis - Effect of sodium lauryl sulphate in the oxidation of cyclopentanol by chromic acid Abs: Cyclopentanol oxidation by Cr-IV in presence and absence of sodium lauryl sulphate (NaLS) is first order in both the reactants. However, the acid dependence changes from a mixed order in absence of NaLS to pure second order in presence of NaLS. The oxidation rate decreases monotonically with [NaLS] above critical micellar concentration. The observation has been rationalised in the light of both Menger-Portnoy model as well as Berezin's model. One of the reactants, viz. Cr-VI is partitioned between the micellar and aqueous phase."
1578253,Saha and  Pal 2005,"Kinetics and mechanism of 1,10-phenanthroline catalysed chromium(VI) oxidation of D-glucose in aqueous micellar media","The kinetics and mechanism of Cr(VI) oxidation of D-glucose in the presence and absence of 1,10-phenanthroline (phen) in aqueous acid media have been studied under the conditions, [sugar](T) >> [Cr(VI)](T) at different temperatures. The monomeric species of Cr(VI) has been found to be kinetically active in the absence of phen whereas in the phen-catalysed path, the Cr(VI)-phen complexes have been found to be the active oxidants. Both the paths show a first order dependence on [sugar](T) and [Cr(VI)](T). The uncatalysed path shows a second order dependence on [H(+)], while the catalysed path shows a first order dependence on [H(+)]. The phen-catalysed path is first-order in [phen](T). These observations remain unaltered in the presence of externally added surfactants. CPC inhibits both pathways while SDS catalyses the reactions.","Kinetics and mechanism of 1,10-phenanthroline catalysed chromium(VI) oxidation of D-glucose in aqueous micellar media Abs: The kinetics and mechanism of Cr(VI) oxidation of D-glucose in the presence and absence of 1,10-phenanthroline (phen) in aqueous acid media have been studied under the conditions, [sugar](T) >> [Cr(VI)](T) at different temperatures. The monomeric species of Cr(VI) has been found to be kinetically active in the absence of phen whereas in the phen-catalysed path, the Cr(VI)-phen complexes have been found to be the active oxidants. Both the paths show a first order dependence on [sugar](T) and [Cr(VI)](T). The uncatalysed path shows a second order dependence on [H(+)], while the catalysed path shows a first order dependence on [H(+)]. The phen-catalysed path is first-order in [phen](T). These observations remain unaltered in the presence of externally added surfactants. CPC inhibits both pathways while SDS catalyses the reactions."
1578252,Saha et al. 2006,Micellar effects on the reactions of chromium(VI) oxidation of lactic acid and malic acid in the presence and absence of picolinic acid in aqueous acid media,"The kinetics and mechanism of Cr(VI) oxidation of lactic acid and malic acid in the presence and absence of picolinic acid (PA) in aqueous acid media have been carried out under the conditions, [alpha-hydroxy acid](T) >> [Cr(VI)](T) at different temperatures. Under the kinetic conditions, the monomeric species of Cr(VI) has been found kinetically active in the absence of PA while in the PA-catalysed path, Cr(VI)-PA complex has been suggested as the active oxidant. Mechanisms for both PA-catalysed and uncatalysed paths, including 2e-transfers, are proposed. The uncatalysed path shows a first order dependence on [H+] while the PA catalysed path shows a zeroth order dependence on [H+]. Both the uncatalysed and PA catalysed paths show the first-order dependence on [alpha-hydroxy acid](T) and [Cr(VI)](T). The PA catalysed path is first order in [PA](T). All these observations (i.e. dependence patterns on the reactants) remain unaltered in the presence of the externally added surfactants. Effect of the cationic surfactant (i.e. cetylpyridinium chloride, CPC) and anionic surfactant (i.e. sodium dodecyl sulphate, SDS) has been studied both in the presence and absence of PA. CPC inhibits the reactions while SDS catalyses the reactions.","Micellar effects on the reactions of chromium(VI) oxidation of lactic acid and malic acid in the presence and absence of picolinic acid in aqueous acid media Abs: The kinetics and mechanism of Cr(VI) oxidation of lactic acid and malic acid in the presence and absence of picolinic acid (PA) in aqueous acid media have been carried out under the conditions, [alpha-hydroxy acid](T) >> [Cr(VI)](T) at different temperatures. Under the kinetic conditions, the monomeric species of Cr(VI) has been found kinetically active in the absence of PA while in the PA-catalysed path, Cr(VI)-PA complex has been suggested as the active oxidant. Mechanisms for both PA-catalysed and uncatalysed paths, including 2e-transfers, are proposed. The uncatalysed path shows a first order dependence on [H+] while the PA catalysed path shows a zeroth order dependence on [H+]. Both the uncatalysed and PA catalysed paths show the first-order dependence on [alpha-hydroxy acid](T) and [Cr(VI)](T). The PA catalysed path is first order in [PA](T). All these observations (i.e. dependence patterns on the reactants) remain unaltered in the presence of the externally added surfactants. Effect of the cationic surfactant (i.e. cetylpyridinium chloride, CPC) and anionic surfactant (i.e. sodium dodecyl sulphate, SDS) has been studied both in the presence and absence of PA. CPC inhibits the reactions while SDS catalyses the reactions."
1578251,Saha et al. 2005,Micellar effect on the catalytic co-oxidation of dimethyl sulfoxide and oxalic acid by chromium(VI) in aqueous acid media: A kinetic study,"The Cr-VI oxidation of a mixture of dimethyl sulfoxide (DMSO) and oxalic acid (OXH2) in aqueous acid media occurs much faster than that of either of the two substrates alone (DMSO reacts extremely slowly under the experimental conditions). In the mixture, both substrates undergo oxidation simultaneously in a ternary complex of Cr-VI through a three electron transfer step (i.e. Cr-VI -> Cr-III), two electrons from DMSO and one electron from oxalic acid. Hitherto there has been a debate regarding the existence of a 3e transfer in a single step. The micellar effect may be considered as a probe for 3e transfer in a single step.","Micellar effect on the catalytic co-oxidation of dimethyl sulfoxide and oxalic acid by chromium(VI) in aqueous acid media: A kinetic study Abs: The Cr-VI oxidation of a mixture of dimethyl sulfoxide (DMSO) and oxalic acid (OXH2) in aqueous acid media occurs much faster than that of either of the two substrates alone (DMSO reacts extremely slowly under the experimental conditions). In the mixture, both substrates undergo oxidation simultaneously in a ternary complex of Cr-VI through a three electron transfer step (i.e. Cr-VI -> Cr-III), two electrons from DMSO and one electron from oxalic acid. Hitherto there has been a debate regarding the existence of a 3e transfer in a single step. The micellar effect may be considered as a probe for 3e transfer in a single step."
1578250,Saha et al. 2004,Micellar effect on the reaction of chromium(VI) oxidation of L-sorbose in the presence and absence of picolinic acid in aqueous acid media: A kinetic study,"The kinetics and mechanism of chromic acid oxidation of L-sorbose in the presence and absence of picolinic acid (PA) have been studied under the conditions, [L-sorbose](T) much greater than [PA](T) much greater than [Cr(VI)](T), at different temperatures. In the absence of PA, the monomeric chromic acid undergoes esterification with the substrate followed by the acid catalysed redox decomposition of the Cr(VI)-substrate ester through glycol splitting to formaldehyde and the lactone Of C-5-aldonic acid and Cr(IV) which subsequently participates in the faster reactions. In the presence of PA, the Cr(VI)-PA complex produced in a pre-equilibrium step experiences a nucleophilic attack by the substrate to produce a ternary complex which decomposes through glycol splitting giving rise to the organic products and Cr(IV)-PA complex. Both the uncatalysed and PA-catalysed paths show the first-order dependence on [L-sorbose]T and [Cr(VI)](T). The PA-catalysed path is first-order in [PA](T) and it shows a fractional order in [H+]. The uncatalysed path shows a second-order dependence on [H+]. In the presence of the surfactants like N-cetylpyridinium chloride (CPC, a cationic surfactant) and sodium dodecyl sulfate (SDS, an anionic sulfate), the reaction orders remain unchanged. CPC has been found to inhibit both the uncatalysed and PA-catalysed paths while SDS shows the rate accelerating effect for both the uncatalysed and PA-catalysed paths. The observed micellar effects have been rationalised by considering the distribution of the reactants between the micellar and aqueous phases in terms of the proposed reaction mechanism.","Micellar effect on the reaction of chromium(VI) oxidation of L-sorbose in the presence and absence of picolinic acid in aqueous acid media: A kinetic study Abs: The kinetics and mechanism of chromic acid oxidation of L-sorbose in the presence and absence of picolinic acid (PA) have been studied under the conditions, [L-sorbose](T) much greater than [PA](T) much greater than [Cr(VI)](T), at different temperatures. In the absence of PA, the monomeric chromic acid undergoes esterification with the substrate followed by the acid catalysed redox decomposition of the Cr(VI)-substrate ester through glycol splitting to formaldehyde and the lactone Of C-5-aldonic acid and Cr(IV) which subsequently participates in the faster reactions. In the presence of PA, the Cr(VI)-PA complex produced in a pre-equilibrium step experiences a nucleophilic attack by the substrate to produce a ternary complex which decomposes through glycol splitting giving rise to the organic products and Cr(IV)-PA complex. Both the uncatalysed and PA-catalysed paths show the first-order dependence on [L-sorbose]T and [Cr(VI)](T). The PA-catalysed path is first-order in [PA](T) and it shows a fractional order in [H+]. The uncatalysed path shows a second-order dependence on [H+]. In the presence of the surfactants like N-cetylpyridinium chloride (CPC, a cationic surfactant) and sodium dodecyl sulfate (SDS, an anionic sulfate), the reaction orders remain unchanged. CPC has been found to inhibit both the uncatalysed and PA-catalysed paths while SDS shows the rate accelerating effect for both the uncatalysed and PA-catalysed paths. The observed micellar effects have been rationalised by considering the distribution of the reactants between the micellar and aqueous phases in terms of the proposed reaction mechanism."
1578249,Saha et al. 2003,Micellar effects on the reaction of Cr(VI) oxidation of hexitols in the presence and absence of picolinic acid in aqueous acid media,"In aqueous acidic media, picolinic acid (PA) promoted Cr-VI-oxidation of the hexitols to the respective aldohexoses goes on, along with a slower uncatalysed path; the anionic surfactant (SIDS) accelerates the process while the cationic surfactant (CPC) retards the reaction.","Micellar effects on the reaction of Cr(VI) oxidation of hexitols in the presence and absence of picolinic acid in aqueous acid media Abs: In aqueous acidic media, picolinic acid (PA) promoted Cr-VI-oxidation of the hexitols to the respective aldohexoses goes on, along with a slower uncatalysed path; the anionic surfactant (SIDS) accelerates the process while the cationic surfactant (CPC) retards the reaction."
1578248,Saha 2008,Micellar Effects on Vanadium(V) Oxidation of Lactic Acid in Aqueous Acid Media: A Kinetic Study,"Vanadium(V) oxidation of lactic acid shows first order dependency on lactic acid, vanadium(V), H(+) and HSO(4)(-). These observations remain unaltered in the presence of externally added surfactants. The effect of adding a cationic surfactant (CPC), anionic surfactant (SDS) and neutral surfactant (TX-100) has been studied. CPC inhibits the reactions while SDS and TX-100 accelerate the reaction to different extents. Observed effects have been explained by considering the hydrophobic and electrostatic interaction between the surfactants and reactants","Micellar Effects on Vanadium(V) Oxidation of Lactic Acid in Aqueous Acid Media: A Kinetic Study Abs: Vanadium(V) oxidation of lactic acid shows first order dependency on lactic acid, vanadium(V), H(+) and HSO(4)(-). These observations remain unaltered in the presence of externally added surfactants. The effect of adding a cationic surfactant (CPC), anionic surfactant (SDS) and neutral surfactant (TX-100) has been studied. CPC inhibits the reactions while SDS and TX-100 accelerate the reaction to different extents. Observed effects have been explained by considering the hydrophobic and electrostatic interaction between the surfactants and reactants"
1578247,Rutland 1991,ENVIRONMENTAL COMPATIBILITY OF CHROMIUM-CONTAINING TANNERY AND OTHER LEATHER PRODUCT WASTES AT LAND DISPOSAL SITES,"Chromium compounds exist in several different oxidation or valence states, the most important being trivalent [Cr(III)] and hexavalent [Cr(VI)]. These two valence states differ significantly in environmental compatibility, so it is important to consider this difference in regulatory and remedial action determinations. Under normal environmental conditions, Cr (VI) compounds are more soluble, more mobile and more toxic, and are the basis for nearly all chromium regulatory standards. Since chromium is the predominant leather tanning agent in use today, most tannery and other leather product wastes contain significant amounts of chromium, which is present exclusively as Cr(III). Federal rules under the Resource Conservation and Recovery Act (RCRA) and the Superfund Act (CERCLA) pertaining to these wastes are in direct conflict, since RCRA recognizes the chromium valence distinction but CERCLA does not. As a consequence, wastes which are classified non-hazardous under RCRA and legally disposed may become a Superfund concern and require costly remediation. Examination of available data indicate such concern is unfounded, as land disposal of Cr(III) waste presents little or no environmental risk. Data from existing land disposal sites show no evidence of Cr(III) migration, Cr(III) oxidation or contamination of groundwater in excess of the Drinking Water Standard. Based on these findings, remediation of Cr(III) wastes at land disposal sites appears entirely unwarranted.","ENVIRONMENTAL COMPATIBILITY OF CHROMIUM-CONTAINING TANNERY AND OTHER LEATHER PRODUCT WASTES AT LAND DISPOSAL SITES Abs: Chromium compounds exist in several different oxidation or valence states, the most important being trivalent [Cr(III)] and hexavalent [Cr(VI)]. These two valence states differ significantly in environmental compatibility, so it is important to consider this difference in regulatory and remedial action determinations. Under normal environmental conditions, Cr (VI) compounds are more soluble, more mobile and more toxic, and are the basis for nearly all chromium regulatory standards. Since chromium is the predominant leather tanning agent in use today, most tannery and other leather product wastes contain significant amounts of chromium, which is present exclusively as Cr(III). Federal rules under the Resource Conservation and Recovery Act (RCRA) and the Superfund Act (CERCLA) pertaining to these wastes are in direct conflict, since RCRA recognizes the chromium valence distinction but CERCLA does not. As a consequence, wastes which are classified non-hazardous under RCRA and legally disposed may become a Superfund concern and require costly remediation. Examination of available data indicate such concern is unfounded, as land disposal of Cr(III) waste presents little or no environmental risk. Data from existing land disposal sites show no evidence of Cr(III) migration, Cr(III) oxidation or contamination of groundwater in excess of the Drinking Water Standard. Based on these findings, remediation of Cr(III) wastes at land disposal sites appears entirely unwarranted."
1578246,Ruotolo and  Gubulin 2005,Chromium(VI) reduction using conducting polymer films,"Reduction of highly toxic hexavalent chromium (Cr(VI)) to its trivalent state (Cr(III)) is necessary to enable further treatment of wastewater by precipitation or adsorption. For this purpose, the present study proposes the use of thin polyaniline films deposited on a large surface area substrate reticulated vitreous carbon (RVC). The influence of electric potential, flow velocity and supporting electrolyte on the reaction rate, current efficiency and energy consumption was investigated for bare RVC and polyaniline-covered RVC. The film stability was also evaluated. The polyaniline thickness was not observed to influence the reaction rate. Also, the synthesis conditions must be controlled in order to guarantee that the substrate surface is completely covered by the polymer. The supporting electrolyte was observed to influence the energy consumption, but not the reaction rate. Flow velocity is very important for process optimization since it improves the mass transfer. Finally, the polyaniline-modified electrode is a promising material for use in Cr(VI) reduction as it remained stable after several cycles and no loss in the reduction rate was observed. (C) 2004 Elsevier B.V. All rights reserved.","Chromium(VI) reduction using conducting polymer films Abs: Reduction of highly toxic hexavalent chromium (Cr(VI)) to its trivalent state (Cr(III)) is necessary to enable further treatment of wastewater by precipitation or adsorption. For this purpose, the present study proposes the use of thin polyaniline films deposited on a large surface area substrate reticulated vitreous carbon (RVC). The influence of electric potential, flow velocity and supporting electrolyte on the reaction rate, current efficiency and energy consumption was investigated for bare RVC and polyaniline-covered RVC. The film stability was also evaluated. The polyaniline thickness was not observed to influence the reaction rate. Also, the synthesis conditions must be controlled in order to guarantee that the substrate surface is completely covered by the polymer. The supporting electrolyte was observed to influence the energy consumption, but not the reaction rate. Flow velocity is very important for process optimization since it improves the mass transfer. Finally, the polyaniline-modified electrode is a promising material for use in Cr(VI) reduction as it remained stable after several cycles and no loss in the reduction rate was observed. (C) 2004 Elsevier B.V. All rights reserved."
1578245,Rodriguez et al. 2011,EVALUATION OF CHROMIUM (VI) TOXICITY TO Chlorella vulgaris Beijerinck CULTURES,"In order to analyze Cr(VI) toxicity, Chlorella vulgaris Beijerinck cultures were exposed for 96h to Cr(VI) (0.000, 0.100, 0.250, 0.350, 0.500, 0.750 and 1.000 mg/l). Several endpoints were measured by conventional methods and flow cytometry (FCM): a) density (FCM, cell counting and spectrophotometry); b) volume and granularity (FCM); c) chlorophyll-a concentration (spectrophotometry) and algal autofluorescence (FL- FCM). Results demonstrate that, except for FL, all parameters were affected by Cr(VI), being cell density the most affected (lowest EC50: 0.332 mg/L- for FCM). Cell volume and granularity were similarly affected. As for FL and chl a concentration, while the first showed no significant differences among treatments, the latter decreased. Taken all together, we demonstrate that Cr(VI) severely affects the parameters tested.","EVALUATION OF CHROMIUM (VI) TOXICITY TO Chlorella vulgaris Beijerinck CULTURES Abs: In order to analyze Cr(VI) toxicity, Chlorella vulgaris Beijerinck cultures were exposed for 96h to Cr(VI) (0.000, 0.100, 0.250, 0.350, 0.500, 0.750 and 1.000 mg/l). Several endpoints were measured by conventional methods and flow cytometry (FCM): a) density (FCM, cell counting and spectrophotometry); b) volume and granularity (FCM); c) chlorophyll-a concentration (spectrophotometry) and algal autofluorescence (FL- FCM). Results demonstrate that, except for FL, all parameters were affected by Cr(VI), being cell density the most affected (lowest EC50: 0.332 mg/L- for FCM). Cell volume and granularity were similarly affected. As for FL and chl a concentration, while the first showed no significant differences among treatments, the latter decreased. Taken all together, we demonstrate that Cr(VI) severely affects the parameters tested."
1578244,Riahi Samani et al. 2011,Influence of Polyaniline Synthesis Conditions on its Capability for Removal and Recovery of Chromium from Aqueous Solution,Absorptive characteristics of polyaniline synthesized in different solvents were studied. Water and mixture of water with other solvents were implemented for polyaniline synthesis. Synthesized polyanilines in powder shape is used as an adsorbent to remove toxic hexavalent chromium from aqueous solutions. Experiments were conducted in batch mode. Removal mechanism involving polyaniline is the combination of surface adsorption and reduction. The kind of solvent used at synthesizing stage can affect the capacity of produced polyanilines for removal of heavy metals including chromium. Synthesized polyaniline in water had the maximum chromium removal efficiency. The morphology study of polyanilines show that the type of solvent used for polymer synthesis affect the morphology of polyaniline.,Influence of Polyaniline Synthesis Conditions on its Capability for Removal and Recovery of Chromium from Aqueous Solution Abs: Absorptive characteristics of polyaniline synthesized in different solvents were studied. Water and mixture of water with other solvents were implemented for polyaniline synthesis. Synthesized polyanilines in powder shape is used as an adsorbent to remove toxic hexavalent chromium from aqueous solutions. Experiments were conducted in batch mode. Removal mechanism involving polyaniline is the combination of surface adsorption and reduction. The kind of solvent used at synthesizing stage can affect the capacity of produced polyanilines for removal of heavy metals including chromium. Synthesized polyaniline in water had the maximum chromium removal efficiency. The morphology study of polyanilines show that the type of solvent used for polymer synthesis affect the morphology of polyaniline.
1578243,Rehman et al. 2011,Evaluation of Batch Biosorption of Chromium (VI) from Aqueous Solution by Chemically Modified Polyalthia longifolia Leaves,"Removal of toxic metals from surface water is a significant matter of concern. Biosorption is emerging as an economical and ecofriendly methodology for the removal of toxic chemicals from waste water. Optimization of operating conditions has a large impact on the efficiency of this process. Simple untreated and chemically modified Polyalthia longifolia leaves were used to study biosorption of Cr (VI) from aqueous media within various experimental conditions and their efficiency of biosorption were compared. The effects of different conditions, such as contact time of solution with biosorbent, temperature, pH, biosorbent dose and agitation speed for the removal of Cr (VI) were studied. It is found that acid treated Polyalthia longifolia leaves have greater biosorption capacity as compared to untreated and base treated leaves. Langmuir and Freundlich isotherms were also applied to evaluate maximum biosorption capacity of simple untreated and chemically modified Polyalthia longifolia leaves for Cr (VI). This research work is of great importance in regard of practical waste water treatment by biosorption.","Evaluation of Batch Biosorption of Chromium (VI) from Aqueous Solution by Chemically Modified Polyalthia longifolia Leaves Abs: Removal of toxic metals from surface water is a significant matter of concern. Biosorption is emerging as an economical and ecofriendly methodology for the removal of toxic chemicals from waste water. Optimization of operating conditions has a large impact on the efficiency of this process. Simple untreated and chemically modified Polyalthia longifolia leaves were used to study biosorption of Cr (VI) from aqueous media within various experimental conditions and their efficiency of biosorption were compared. The effects of different conditions, such as contact time of solution with biosorbent, temperature, pH, biosorbent dose and agitation speed for the removal of Cr (VI) were studied. It is found that acid treated Polyalthia longifolia leaves have greater biosorption capacity as compared to untreated and base treated leaves. Langmuir and Freundlich isotherms were also applied to evaluate maximum biosorption capacity of simple untreated and chemically modified Polyalthia longifolia leaves for Cr (VI). This research work is of great importance in regard of practical waste water treatment by biosorption."
1578242,Reddithota et al. 2007,Electrocoagulation: A cleaner method for treatment of Cr(VI) from electroplating industrial effluents,"Chromium contamination in waters are highly toxic even in very low concentrations and need to be completely removed from the effluents before they are discharged into a stream, sewer or on land. Electroplating industry is one of the industrial sectors producing chromium bearing wastewaters, mostly originating from chromium plating, anodizing electroplating solutions and dip solutions like passivating dips, bright dips, etc. Chromium concentration in the effluents varies from 3 to 50 mg/L depending upon the care with which the plating operations are carried out. The results of this study have shown the applicability of electrocoagulation as a clean method for treatment of Cr(VI) containing wastewaters. The optimum removal of Cr(VI) was attained between pH 4-8. Increase in current density enhances the removal rate and the quickest treatment with an effective reduction of Cr(VI) concentrations was achieved below permissible level within 20 min. Iron electrodes were found to be more efficient in removing chromium in comparison to the aluminum and hydrid Al/Fe electrodes. This may be due to the formation of stable Fe-Cr complex which is more stable than Al-Cr complexes. On the other hand, I kg of Cr(VI) removal produces only 2,8 kg of sludge against 36 kg of sludge generated from iron sulphate precipitation method. The rate of removal is faster in comparison to the adsorption on activated carbon which is one of the most important requirement for practical application of this treatment method.","Electrocoagulation: A cleaner method for treatment of Cr(VI) from electroplating industrial effluents Abs: Chromium contamination in waters are highly toxic even in very low concentrations and need to be completely removed from the effluents before they are discharged into a stream, sewer or on land. Electroplating industry is one of the industrial sectors producing chromium bearing wastewaters, mostly originating from chromium plating, anodizing electroplating solutions and dip solutions like passivating dips, bright dips, etc. Chromium concentration in the effluents varies from 3 to 50 mg/L depending upon the care with which the plating operations are carried out. The results of this study have shown the applicability of electrocoagulation as a clean method for treatment of Cr(VI) containing wastewaters. The optimum removal of Cr(VI) was attained between pH 4-8. Increase in current density enhances the removal rate and the quickest treatment with an effective reduction of Cr(VI) concentrations was achieved below permissible level within 20 min. Iron electrodes were found to be more efficient in removing chromium in comparison to the aluminum and hydrid Al/Fe electrodes. This may be due to the formation of stable Fe-Cr complex which is more stable than Al-Cr complexes. On the other hand, I kg of Cr(VI) removal produces only 2,8 kg of sludge against 36 kg of sludge generated from iron sulphate precipitation method. The rate of removal is faster in comparison to the adsorption on activated carbon which is one of the most important requirement for practical application of this treatment method."
1578241,Rao et al. 1992,KINETIC-STUDIES ON ADSORPTION OF CHROMIUM BY COCONUT SHELL CARBONS FROM SYNTHETIC EFFLUENTS,"The present work deals with the kinetics of chromium (vi) removal from prepared activated coconut shell carbons. The activated carbons were prepared by physical and chemical activation using H2SO4, H3PO4, ZnCl2 activating agents of different Imprignation Ratio (IR). The effect of adsorption of Cr (vi) on pH, particle size concentration, contact time have been studied. Removal of cromium (vi) attained an equilibrium maximum of 70 mins. and slightly decreases with increasing IR. Adsorption obeys First order rate equation and Webber and Morris equation for pore diffusion. Adsorption increases with decrease in pH, is maximum at pH l. Increase in imprignation ratio also increses surface area of coconut shell carbons.","KINETIC-STUDIES ON ADSORPTION OF CHROMIUM BY COCONUT SHELL CARBONS FROM SYNTHETIC EFFLUENTS Abs: The present work deals with the kinetics of chromium (vi) removal from prepared activated coconut shell carbons. The activated carbons were prepared by physical and chemical activation using H2SO4, H3PO4, ZnCl2 activating agents of different Imprignation Ratio (IR). The effect of adsorption of Cr (vi) on pH, particle size concentration, contact time have been studied. Removal of cromium (vi) attained an equilibrium maximum of 70 mins. and slightly decreases with increasing IR. Adsorption obeys First order rate equation and Webber and Morris equation for pore diffusion. Adsorption increases with decrease in pH, is maximum at pH l. Increase in imprignation ratio also increses surface area of coconut shell carbons."
1578240,Rao et al. 2008,Cytogenetic Alteration Induced by Nickel and Chromium in Human Blood Cultures and its Amelioration by Curcumin,"Tanners, welders and workers in various industries are exposed to acute and chronic toxicity of these heavy metals world wide. The present work is undertaken to evaluate the genotoxic effects of Ni and Cr at two different exposure intervals with a single dose and the amelioration of this toxicity using curcumin. Ni in form of nickel chloride (4.216 X 10(-5)M) and Cr as potassium dichromate (1.36 X 10(-6)M) were exposed for 24 and 69 hours to human blood lymphocyte cultures. The genotoxicity was measured by changes in acrocentric and telomeric association and C-anaphase. Results revealed a significant positive correlation between DNA damage and exposure time in Ni and Cr added cultures alone. Likewise it was also observed in cultures with combination of both pro-oxidants. Groups supplemented with curcumin (3.87 X 10(-7)M) showed insignificant cytogenetic damage indicating its protective role which was calculated as percentage amelioration. Thus these data proved curcumin as a protective agent against Ni and Cr induced genotoxicity.","Cytogenetic Alteration Induced by Nickel and Chromium in Human Blood Cultures and its Amelioration by Curcumin Abs: Tanners, welders and workers in various industries are exposed to acute and chronic toxicity of these heavy metals world wide. The present work is undertaken to evaluate the genotoxic effects of Ni and Cr at two different exposure intervals with a single dose and the amelioration of this toxicity using curcumin. Ni in form of nickel chloride (4.216 X 10(-5)M) and Cr as potassium dichromate (1.36 X 10(-6)M) were exposed for 24 and 69 hours to human blood lymphocyte cultures. The genotoxicity was measured by changes in acrocentric and telomeric association and C-anaphase. Results revealed a significant positive correlation between DNA damage and exposure time in Ni and Cr added cultures alone. Likewise it was also observed in cultures with combination of both pro-oxidants. Groups supplemented with curcumin (3.87 X 10(-7)M) showed insignificant cytogenetic damage indicating its protective role which was calculated as percentage amelioration. Thus these data proved curcumin as a protective agent against Ni and Cr induced genotoxicity."
1578239,Rafique et al. 2010,Toxic Chromium from Tanneries Pollute Water Resources and Soils of Sialkot (Pakistan),"The present investigation reports the concentrations of total chromium and its species i e chromium (Cr (III) and Cr (VI)) assessed in soil drinking water and effluents of tanneries distributed in ten clusters of Sialkot District Pakistan 120 samples consisting 40 samples each of topsoil drinking water and composite wastewater were collected from the selected tannery clusters The chelation extraction and digestion method followed by atomic absorption spectrometer were used to analyze Cr (VI) and total Cr respectively in soil, wastewater and drinking water at 427 nm and 540 nm respectively The concentration of total chromium Cr (III) and Cr (VI) in wastewater drinking water and soil was found to be in range of (Cr) 16 12-36 83 mg/L 1 0483-3 1824 mg/L and 3 45-11 43 mg/kg (Cr (III) 0 97-13 25 mg/L 0-1 05 and 1 56-9 80 mg/kg and Cr (VI)11 6928 61 ppm 083 596 ppm and 2 12-11 86 ppm respectively The concentrations of chromium contents are above the National Environmental Standard of Pakistan It was found that pH above 6 leads to higher concentration of Cr (VI) in the samples due to oxidation behavior The study recommends the treatment of wastewater before being discharged","Toxic Chromium from Tanneries Pollute Water Resources and Soils of Sialkot (Pakistan) Abs: The present investigation reports the concentrations of total chromium and its species i e chromium (Cr (III) and Cr (VI)) assessed in soil drinking water and effluents of tanneries distributed in ten clusters of Sialkot District Pakistan 120 samples consisting 40 samples each of topsoil drinking water and composite wastewater were collected from the selected tannery clusters The chelation extraction and digestion method followed by atomic absorption spectrometer were used to analyze Cr (VI) and total Cr respectively in soil, wastewater and drinking water at 427 nm and 540 nm respectively The concentration of total chromium Cr (III) and Cr (VI) in wastewater drinking water and soil was found to be in range of (Cr) 16 12-36 83 mg/L 1 0483-3 1824 mg/L and 3 45-11 43 mg/kg (Cr (III) 0 97-13 25 mg/L 0-1 05 and 1 56-9 80 mg/kg and Cr (VI)11 6928 61 ppm 083 596 ppm and 2 12-11 86 ppm respectively The concentrations of chromium contents are above the National Environmental Standard of Pakistan It was found that pH above 6 leads to higher concentration of Cr (VI) in the samples due to oxidation behavior The study recommends the treatment of wastewater before being discharged"
1578238,Prokhotskaia and  Dmitrieva 2002,Types of algal population responses to heavy metal action,"A usual behavior of biological systems is three-phase response to treatment dose (""paradoxical reaction""). It means that low and high doses of factor cause a stronger response than moderate ones. We were shown earlier that nonlinear concentration-effect curve reflects a hierarchy of cell responses to increasing concentrations of damaging factor: inhibition of cell division at low concentrations; stress and adaptive increasinig of resistance at moderate concentrations and premature cell division and death at high concentrations. In this work, we analyzed the dynamics of the population structure and cell functional characteristics (photosynthesis) of laboratory green alga Scenedesmus quadricauda (Turp.) Breb. population. Thereby, we found the main types of algal reaction to the toxicant (potassium dichromate, K(2)Cr(2)O(7)) action. At low K(2)Cr(2)O(7) concentration (0.001 mg/l) the total cell number decreasing was not related to cell death. The decrease of the growth rate in this case was due to the long-term cell division inhibition in a fraction of cell population but toxicant did not have strong effect on the photosynthetic activity as compared to control culture. At moderate, seemingly inactive concentrations (0.01-0.1 mg/l) the absence of effect is caused by renewal of cell division after temporary arrest. During the arrest of cell division, the efficiency of photosynthesis decreased only slightly but restored within two days. At these concentrations toxicant induced cell stress and adaptive elevation of cell tolerance. At medium toxic concentrations (1.0-3.0 mg/l) we can observe long-term cell division inhibition and giant cells forming but such a state of the algae was reversible: giant cells rapidly resumed their division after being transferred to a toxicant-free medium. Sublethal K(2)Cr(2)O(7) concentrations did not significantly inhibit photosynthesis. At lethal concentration (10.0 mg/l) the cell division is stimulated and the small immature cells predominated in the beginning of intoxication. The toxicant caused reducing photosynthetic efficiency to a double as compared to control level. It indicated irreversible cell damage. Thus, changes of the population structure characterize its state. We can recommend using described types of reaction to the toxic action for risk assessment and biotesting. It is known that the population number changes by complex way in increasing of damaging factors intensity. A usual behavior of biological systems is three-phase response to treatment dose (""paradoxical reaction""). It means that low and high doses of factor cause a stronger response than moderate ones [1, 2]. We have shown earlier that nonlinear concentration response curve of cell survival reflects of hierarchy of cell responses to increasing concentration of fungicide imazalil sulfate: cell division inhibition in low doses, stress and adaptive tolerance increasing in moderate doses and immature cell division and cell death in high doses [3]. The purpose of our research was to reveal the main principles of algal population response to the toxicant (potassium dichromate, K(2)Cr(2)O(7)). Moreover, we display a possibility of their using as a diagnostic tool for biotesting.","Types of algal population responses to heavy metal action Abs: A usual behavior of biological systems is three-phase response to treatment dose (""paradoxical reaction""). It means that low and high doses of factor cause a stronger response than moderate ones. We were shown earlier that nonlinear concentration-effect curve reflects a hierarchy of cell responses to increasing concentrations of damaging factor: inhibition of cell division at low concentrations; stress and adaptive increasinig of resistance at moderate concentrations and premature cell division and death at high concentrations. In this work, we analyzed the dynamics of the population structure and cell functional characteristics (photosynthesis) of laboratory green alga Scenedesmus quadricauda (Turp.) Breb. population. Thereby, we found the main types of algal reaction to the toxicant (potassium dichromate, K(2)Cr(2)O(7)) action. At low K(2)Cr(2)O(7) concentration (0.001 mg/l) the total cell number decreasing was not related to cell death. The decrease of the growth rate in this case was due to the long-term cell division inhibition in a fraction of cell population but toxicant did not have strong effect on the photosynthetic activity as compared to control culture. At moderate, seemingly inactive concentrations (0.01-0.1 mg/l) the absence of effect is caused by renewal of cell division after temporary arrest. During the arrest of cell division, the efficiency of photosynthesis decreased only slightly but restored within two days. At these concentrations toxicant induced cell stress and adaptive elevation of cell tolerance. At medium toxic concentrations (1.0-3.0 mg/l) we can observe long-term cell division inhibition and giant cells forming but such a state of the algae was reversible: giant cells rapidly resumed their division after being transferred to a toxicant-free medium. Sublethal K(2)Cr(2)O(7) concentrations did not significantly inhibit photosynthesis. At lethal concentration (10.0 mg/l) the cell division is stimulated and the small immature cells predominated in the beginning of intoxication. The toxicant caused reducing photosynthetic efficiency to a double as compared to control level. It indicated irreversible cell damage. Thus, changes of the population structure characterize its state. We can recommend using described types of reaction to the toxic action for risk assessment and biotesting. It is known that the population number changes by complex way in increasing of damaging factors intensity. A usual behavior of biological systems is three-phase response to treatment dose (""paradoxical reaction""). It means that low and high doses of factor cause a stronger response than moderate ones [1, 2]. We have shown earlier that nonlinear concentration response curve of cell survival reflects of hierarchy of cell responses to increasing concentration of fungicide imazalil sulfate: cell division inhibition in low doses, stress and adaptive tolerance increasing in moderate doses and immature cell division and cell death in high doses [3]. The purpose of our research was to reveal the main principles of algal population response to the toxicant (potassium dichromate, K(2)Cr(2)O(7)). Moreover, we display a possibility of their using as a diagnostic tool for biotesting."
1578237,Proctor et al. 1997,Health-based soil action levels for trivalent and hexavalent chromium: A comparison with state and federal standards,"BIOSIS COPYRIGHT: BIOL ABS. As part of the Brownfields initiatives being enacted at both the state and federal levels, environmental regulatory agencies are developing health-based screening or action levels to facilitate the reclamation of unused industrial properties. By the end of 1997, approximately 90% of the states will have either adopted federal values or developed their own non-site-specific action levels. These standards can be applied as default cleanup levels, or alternative remediation standards maybe developed based on a site-specific risk assessment. A state and federal survey of cleanup levels for hexavalent and trivalent chromium (Cr(VI) and Cr(III)) indicated a general concurrence of approaches (i.e., most states are using the USEPA standard risk assessment model with upper-bound estimates of exposure and USEPA toxicity criteria), although the proposed values vary by as much as 5 orders of magnitude. To understand the variability and uncertainty in these levels, the USEPA Soil S","Health-based soil action levels for trivalent and hexavalent chromium: A comparison with state and federal standards Abs: BIOSIS COPYRIGHT: BIOL ABS. As part of the Brownfields initiatives being enacted at both the state and federal levels, environmental regulatory agencies are developing health-based screening or action levels to facilitate the reclamation of unused industrial properties. By the end of 1997, approximately 90% of the states will have either adopted federal values or developed their own non-site-specific action levels. These standards can be applied as default cleanup levels, or alternative remediation standards maybe developed based on a site-specific risk assessment. A state and federal survey of cleanup levels for hexavalent and trivalent chromium (Cr(VI) and Cr(III)) indicated a general concurrence of approaches (i.e., most states are using the USEPA standard risk assessment model with upper-bound estimates of exposure and USEPA toxicity criteria), although the proposed values vary by as much as 5 orders of magnitude. To understand the variability and uncertainty in these levels, the USEPA Soil S"
1578235,Plesu et al. 2003,Reduction of Cr(VI) using polyaniline-polystyrene-divinyl benzene gels,"The toxicity of hexavalent chromium was proven in the last years, and the concentration in residual waters deriving from a variety of applications like dye production, electroplating, tannery, is necessary to be bellow 0.1 mg/L. In this paper the reduction of hexavalent chromium to trivalent chromium, a less toxic species, is possible using a composite polyaniline-polystyrene-divinylbenzene gels. The synthesis of composite polymers and hexavalent chromium reduction rate was evaluated.","Reduction of Cr(VI) using polyaniline-polystyrene-divinyl benzene gels Abs: The toxicity of hexavalent chromium was proven in the last years, and the concentration in residual waters deriving from a variety of applications like dye production, electroplating, tannery, is necessary to be bellow 0.1 mg/L. In this paper the reduction of hexavalent chromium to trivalent chromium, a less toxic species, is possible using a composite polyaniline-polystyrene-divinylbenzene gels. The synthesis of composite polymers and hexavalent chromium reduction rate was evaluated."
1578234,Perezbenito et al. 1994,CHROMIUM(II) IS AN INTERMEDIATE IN THE REDUCTION OF CARCINOGENIC CHROMATE WITH BIOLOGICAL THIOLS,"Superoxochromium(III), CrO22+, has been detected by UV spectroscopy in the aqueous reduction of Cr(VI) by biological thiols (DL-penicillamine, L-cysteine, and glutathione) in the presence of O-2 under conditions of near-physiological pH, thus evidencing that Cr2+ is an intermediate in these reactions. It is proposed that this intermediate might be an active agent in the mechanism of carcinogenesis caused by chromium(VI) compounds.","CHROMIUM(II) IS AN INTERMEDIATE IN THE REDUCTION OF CARCINOGENIC CHROMATE WITH BIOLOGICAL THIOLS Abs: Superoxochromium(III), CrO22+, has been detected by UV spectroscopy in the aqueous reduction of Cr(VI) by biological thiols (DL-penicillamine, L-cysteine, and glutathione) in the presence of O-2 under conditions of near-physiological pH, thus evidencing that Cr2+ is an intermediate in these reactions. It is proposed that this intermediate might be an active agent in the mechanism of carcinogenesis caused by chromium(VI) compounds."
1578233,Pavel et al. 2012,EVALUATION OF HEAVY METALS TOXICITY ON TWO MICROBIAL STRAINS ISOLATED FROM SOIL: Azotobacter sp. AND Pichia sp,"Chromium and cadmium are heavy metals that occur naturally in the environment and especially in soils. Their toxic effect is more pronounced at high concentrations and it depends on the oxidation states. While Cr (III) is considered an essential trace element for the metabolism of living organisms, Cr (VI) has a higher mobility and is easily soluble in soils and can be leached into surface water or groundwater, and taken up by plants. That leads to a toxic and carcinogenic effect to humans via inhalation for long exposures. The concentrations and the form of heavy metals in soils and the behavior of their free ions in soils solution are influenced by soil pH, organic matter (OM) content, cation exchange capacity (CEC), and clay mineralogy. This work presents the toxicity effect of two common heavy metals that can be found in soil (chromium and cadmium) on two microbial strains, which are also isolated from soil: Azotobacter sp. and Pichia sp. Batch tests where made using different concentrations of the selected heavy metals and culture medium: for Azotobacter sp. strain was used a Sabouraud medium and for Pichia sp. strain a YEPD medium (Yeast Extract, Pepton, Dextrose). The dry weights of the microbial culture were used to determine the microbial growing, calculated in percent inhibition of dry weight versus concentrations of metal ions.","EVALUATION OF HEAVY METALS TOXICITY ON TWO MICROBIAL STRAINS ISOLATED FROM SOIL: Azotobacter sp. AND Pichia sp Abs: Chromium and cadmium are heavy metals that occur naturally in the environment and especially in soils. Their toxic effect is more pronounced at high concentrations and it depends on the oxidation states. While Cr (III) is considered an essential trace element for the metabolism of living organisms, Cr (VI) has a higher mobility and is easily soluble in soils and can be leached into surface water or groundwater, and taken up by plants. That leads to a toxic and carcinogenic effect to humans via inhalation for long exposures. The concentrations and the form of heavy metals in soils and the behavior of their free ions in soils solution are influenced by soil pH, organic matter (OM) content, cation exchange capacity (CEC), and clay mineralogy. This work presents the toxicity effect of two common heavy metals that can be found in soil (chromium and cadmium) on two microbial strains, which are also isolated from soil: Azotobacter sp. and Pichia sp. Batch tests where made using different concentrations of the selected heavy metals and culture medium: for Azotobacter sp. strain was used a Sabouraud medium and for Pichia sp. strain a YEPD medium (Yeast Extract, Pepton, Dextrose). The dry weights of the microbial culture were used to determine the microbial growing, calculated in percent inhibition of dry weight versus concentrations of metal ions."
1578232,Pavel et al. 2010,ANALYSIS OF FACTORS DETERMINING THE BEHAVIOUR OF CHROMIUM IN SOME ROMANIAN SOILS,"Chromium (Cr) is one of the most common metal contaminants in soil because of its use in ore refining, production of steel and alloys, metal plating, tanneries, wood preservation, and pigmentation. In soil environment, the most stable oxidation states of chromium are Cr (III) and Cr (VI). While Cr (III) is considered an essential trace element for the functioning of living organisms, Cr (VI) is toxic and carcinogenic to humans via inhalation for long exposures, since it is easily soluble and mobile in soils and can be leached into surface water or groundwater, and taken up by plants. The efficacy of remediation processes are highly dependent on chromium sorption and desorption kinetics and on the influence of competing solute anions. Models to predict the transport of Cr(VI) in soils must therefore incorporate these effects. The objective of the study was to speciate and to evaluate various soil Cr species in relation to soil properties. Adsorption and reduction of added Cr(VI) were characterized in soils with contrasting pH, organic matter contents, and chemical and mineralogical properties. Batch experiments are used to determine equilibrium sorption parameters for chromium by soil and to study sorption kinetics that are relevant to soil contamination sites. The distribution of metal contaminant in soils can be strongly localized by transport limitations and redox gradients within soil aggregates. The soils adsorption and reduction capacities were eventually overwhelmed, however, and permitted the passage of Cr(VI) into the underlying ground water.","ANALYSIS OF FACTORS DETERMINING THE BEHAVIOUR OF CHROMIUM IN SOME ROMANIAN SOILS Abs: Chromium (Cr) is one of the most common metal contaminants in soil because of its use in ore refining, production of steel and alloys, metal plating, tanneries, wood preservation, and pigmentation. In soil environment, the most stable oxidation states of chromium are Cr (III) and Cr (VI). While Cr (III) is considered an essential trace element for the functioning of living organisms, Cr (VI) is toxic and carcinogenic to humans via inhalation for long exposures, since it is easily soluble and mobile in soils and can be leached into surface water or groundwater, and taken up by plants. The efficacy of remediation processes are highly dependent on chromium sorption and desorption kinetics and on the influence of competing solute anions. Models to predict the transport of Cr(VI) in soils must therefore incorporate these effects. The objective of the study was to speciate and to evaluate various soil Cr species in relation to soil properties. Adsorption and reduction of added Cr(VI) were characterized in soils with contrasting pH, organic matter contents, and chemical and mineralogical properties. Batch experiments are used to determine equilibrium sorption parameters for chromium by soil and to study sorption kinetics that are relevant to soil contamination sites. The distribution of metal contaminant in soils can be strongly localized by transport limitations and redox gradients within soil aggregates. The soils adsorption and reduction capacities were eventually overwhelmed, however, and permitted the passage of Cr(VI) into the underlying ground water."
1578231,Parma et al. 2008,"Uptake and elimination of chromium in Cnesterodon decemmaculatus; Pisces : Poeciliidae, after sub-chronic experimental exposure","The objective of this study was to evaluate the capacity of bioconcentration and elimination of chromium by Cnesterodon decemmaculatus in experimental conditions. PVC tanks (800 L), with a sandy, kaolinite and turf sediment were used. Amounts of 3 and 6 mg Cr/L of potassium dichromate in dechlorinated water were added to the sediment using two replicates per concentration and control. After 5 days of stabilization, 125 specimens (1.7-2.8 cm total length) from our own cultures were placed in each tank. Water, sediment and fish (10 specimens pooled) samples were taken at 1, 7, 14 and 28 days during the accumulation phase, and at 1, 7 and 14 days during depuration phase. Temperature, dissolved oxygen, conductivity, pH, and salinity were daily registered. The bioconcentration factors (tissue/water) were 3.51 and 4.00 for 3 and 6 mg Cr/L levels, respectively, after 7 days; 2.15 and 1.97 at 14(th) day, and 6.15 and 2.63 at 28(th) day of the accumulation phase. After 14 days, the depuration phase revealed 100% elimination at 3 mg Cr/L and approximately 61% elimination at 6 mg Cr/L.","Uptake and elimination of chromium in Cnesterodon decemmaculatus; Pisces : Poeciliidae, after sub-chronic experimental exposure Abs: The objective of this study was to evaluate the capacity of bioconcentration and elimination of chromium by Cnesterodon decemmaculatus in experimental conditions. PVC tanks (800 L), with a sandy, kaolinite and turf sediment were used. Amounts of 3 and 6 mg Cr/L of potassium dichromate in dechlorinated water were added to the sediment using two replicates per concentration and control. After 5 days of stabilization, 125 specimens (1.7-2.8 cm total length) from our own cultures were placed in each tank. Water, sediment and fish (10 specimens pooled) samples were taken at 1, 7, 14 and 28 days during the accumulation phase, and at 1, 7 and 14 days during depuration phase. Temperature, dissolved oxygen, conductivity, pH, and salinity were daily registered. The bioconcentration factors (tissue/water) were 3.51 and 4.00 for 3 and 6 mg Cr/L levels, respectively, after 7 days; 2.15 and 1.97 at 14(th) day, and 6.15 and 2.63 at 28(th) day of the accumulation phase. After 14 days, the depuration phase revealed 100% elimination at 3 mg Cr/L and approximately 61% elimination at 6 mg Cr/L."
1578230,Pantani et al. 1989,"ACTION OF TEMPERATURE AND WATER HARDNESS ON THE TOXICITY OF HEXAVALENT CHROMIUM IN GAMMARUS-ITALICUS GOEDM (CRUSTACEA, AMPHIPODA)",,"ACTION OF TEMPERATURE AND WATER HARDNESS ON THE TOXICITY OF HEXAVALENT CHROMIUM IN GAMMARUS-ITALICUS GOEDM (CRUSTACEA, AMPHIPODA) Abs: "
1578229,Panigrahi and  Sahu 1996,Effect of sodium lauryl sulphate micelle in the oxidation of dl-mandelic acid by Cr(VI),dl-Mandelic acid on oxidation by Cr(VI) in the absence and presence of sodium lauryl sulphate (NaLS) follows a route conforming to Michaelis-Menten kinetics. Rate data in the presence of [H+] show an acid dependent and acid independent path. Entropy of activation is found to be negative. Rate of oxidation is mildly enhanced in the presence of increasing concentration of NaLS upto the CMC value of NaLS beyond which rate decreases. An attempt has been made to rationalist the observations.,Effect of sodium lauryl sulphate micelle in the oxidation of dl-mandelic acid by Cr(VI) Abs: dl-Mandelic acid on oxidation by Cr(VI) in the absence and presence of sodium lauryl sulphate (NaLS) follows a route conforming to Michaelis-Menten kinetics. Rate data in the presence of [H+] show an acid dependent and acid independent path. Entropy of activation is found to be negative. Rate of oxidation is mildly enhanced in the presence of increasing concentration of NaLS upto the CMC value of NaLS beyond which rate decreases. An attempt has been made to rationalist the observations.
1578228,Panigrahi and  Misra 1990,MICELLAR CATALYSIS IN THE OXIDATION OF CYCLOHEXANOL BY CHROMIUM(VI),,MICELLAR CATALYSIS IN THE OXIDATION OF CYCLOHEXANOL BY CHROMIUM(VI) Abs: 
1578227,Panigrahi and  Mishra 1993,MICELLAR EFFECT IN THE OXIDATION OF MALIC-ACID BY CHROMIC-ACID,Oxidation of malic acid by Cr(VI) in the absence and presence of sodium lauryl sulphate (NaLS) is routed through the same mechanism as shown by the kinetic study. The oxidation rate is inhibited in the presence of sodium lauryl sulphate. The inhibition has been traced to partition of the Cr(VI) species as well as the acid concentration between the aqueous and micellar phase. The kinetic results indicate that the reaction occurs in the aqueous phase in the presence of much reduced concentration of H+ ion.,MICELLAR EFFECT IN THE OXIDATION OF MALIC-ACID BY CHROMIC-ACID Abs: Oxidation of malic acid by Cr(VI) in the absence and presence of sodium lauryl sulphate (NaLS) is routed through the same mechanism as shown by the kinetic study. The oxidation rate is inhibited in the presence of sodium lauryl sulphate. The inhibition has been traced to partition of the Cr(VI) species as well as the acid concentration between the aqueous and micellar phase. The kinetic results indicate that the reaction occurs in the aqueous phase in the presence of much reduced concentration of H+ ion.
1578226,Panigrahi and  Mishra 1992,INFLUENCE OF SODIUM LAURYL SULFATE MICELLES ON THE OXIDATION OF MALONIC-ACID BY CHROMIC-ACID,Malonic acid oxidation by Cr(VI) in the presence of sodium lauryl sulfate micelle is first order each in [Cr(VI)] and [H+] but second order in malonic acid. The oxidation is inhibited by NaLS. The observed reactions can be explained with the model proposed by Menger and Portnoy but does not fit to Berezin's model. The treatment leads to the conclusion that the reaction occurs in the aqueous phase and the active Cr(VI) species is H2CrO4.,INFLUENCE OF SODIUM LAURYL SULFATE MICELLES ON THE OXIDATION OF MALONIC-ACID BY CHROMIC-ACID Abs: Malonic acid oxidation by Cr(VI) in the presence of sodium lauryl sulfate micelle is first order each in [Cr(VI)] and [H+] but second order in malonic acid. The oxidation is inhibited by NaLS. The observed reactions can be explained with the model proposed by Menger and Portnoy but does not fit to Berezin's model. The treatment leads to the conclusion that the reaction occurs in the aqueous phase and the active Cr(VI) species is H2CrO4.
1578225,Pandey et al. 2004,Aggregation in oxidation of aspartic and glutamic acids by chloramine-T in presence of surfactants: A kinetic study,"The kinetics of oxidation of aspartic and glutamic acids by chloramine-T in HClO4 medium have been investigated in the absence and presence of anionic (sodium lauryl sulphate), cationic (cetyltrimethylammonium bromide) and non-ionic (Brij 35) surfactants. In the absence of surfactant the rate of oxidation may be represented as, d[Chloramine-T]/dt = k[Chloramine-T](2)[Amino acid]/{1+K[H+]} where k and K are constants. The presence of a small amount of surfactant (below its critical micelle concentration) strongly enhances the rate of oxidation and the observed rate constant attains constancy at higher surfactant concentration. Using Piszkiewicz's cooperativity model, the cooperative index n has been calculated for these reactions to be between 1-3, indicating the existence of catalytically productive submicellar aggregates. The values of n have been used to calculate the binding constants of reactants with the surfactant using Raghvan and Srinivasan's model proposed for biomolecular micellar catalysed reactions. The evaluated binding constants are in good agreement front those obtained by Piszkiewicz's model. The formation of aggregate is further supported by the enhancement of rate in presence of a common hydrotrope, namely, sodium benzoate.","Aggregation in oxidation of aspartic and glutamic acids by chloramine-T in presence of surfactants: A kinetic study Abs: The kinetics of oxidation of aspartic and glutamic acids by chloramine-T in HClO4 medium have been investigated in the absence and presence of anionic (sodium lauryl sulphate), cationic (cetyltrimethylammonium bromide) and non-ionic (Brij 35) surfactants. In the absence of surfactant the rate of oxidation may be represented as, d[Chloramine-T]/dt = k[Chloramine-T](2)[Amino acid]/{1+K[H+]} where k and K are constants. The presence of a small amount of surfactant (below its critical micelle concentration) strongly enhances the rate of oxidation and the observed rate constant attains constancy at higher surfactant concentration. Using Piszkiewicz's cooperativity model, the cooperative index n has been calculated for these reactions to be between 1-3, indicating the existence of catalytically productive submicellar aggregates. The values of n have been used to calculate the binding constants of reactants with the surfactant using Raghvan and Srinivasan's model proposed for biomolecular micellar catalysed reactions. The evaluated binding constants are in good agreement front those obtained by Piszkiewicz's model. The formation of aggregate is further supported by the enhancement of rate in presence of a common hydrotrope, namely, sodium benzoate."
1578224,Ozkoc and  Taylan 2010,ASSESSMENT OF VARIOUS PARAMETERS OF METAL BIOLOGY IN MARINE MICROALGAE PHAEODACTYLUM TRICORNUTUM AND DUNALIELLA TERTIOLECTA,"This work reports on the variations in copper and zinc uptake, accumulation, toxicity, and chlorophyll-a contents in two marine algae, Dunaliella tertiolecta and Phaeodactylum tricornutum, that are important in the food chain and widely used as indicators. Each of the heavy metals tested was applied to a batch system over a period of 96 h applying high metal concentration (5-50 mg L(-1)). Experimental results showed that there was an increase in bioaccumulation in both Phaeodactylum tricornutum. and Dunaliella tertiolecta. The highest decrease in chlorophyll-a concentration was in 5 mg L(-1) copper solution of Phaeodactylum tricornutum. In both organisms, copper was found to be much more toxic than zinc. As metal concentration and exposure time were increased, the metal uptake into cells decreased but the amount of adsorbed metal on cell surfaces increased.","ASSESSMENT OF VARIOUS PARAMETERS OF METAL BIOLOGY IN MARINE MICROALGAE PHAEODACTYLUM TRICORNUTUM AND DUNALIELLA TERTIOLECTA Abs: This work reports on the variations in copper and zinc uptake, accumulation, toxicity, and chlorophyll-a contents in two marine algae, Dunaliella tertiolecta and Phaeodactylum tricornutum, that are important in the food chain and widely used as indicators. Each of the heavy metals tested was applied to a batch system over a period of 96 h applying high metal concentration (5-50 mg L(-1)). Experimental results showed that there was an increase in bioaccumulation in both Phaeodactylum tricornutum. and Dunaliella tertiolecta. The highest decrease in chlorophyll-a concentration was in 5 mg L(-1) copper solution of Phaeodactylum tricornutum. In both organisms, copper was found to be much more toxic than zinc. As metal concentration and exposure time were increased, the metal uptake into cells decreased but the amount of adsorbed metal on cell surfaces increased."
1578223,Orozco et al. 2007,Hexavalent chromium removal using aerobic activated sludge batch systems added with powdered activated carbon,"The addition of powdered activated carbon (PAC) has been proposed as a suitable technique to protect activated sludge against toxic wastewaters. However, the literature data describing the combined effect of PAC addition on Cr(VI) removal using activated sludge are scarce. The objectives of this study were to investigate the effect of the initial Cr(VI) concentration, PAC and an electron donor addition on Cr(VI) removal using aerobic activated sludge batch reactors. The following Cr(VI) removal systems were tested: activated sludge alone; activated sludge with an external electron donor (5 g/l of lactose); activated sludge with PAC addition (4 g/l); activated sludge with both PAC and lactose; and PAC alone. The results reported here showed that activated sludges are capable of removing Cr(VI) via its reduction to Cr(III) only if a suitable electron donor (such as lactose) is available. For initial Cr(VI) concentration lower than 10 mg/l, biomass alone can remove 100% of the Cr(VI). However, for higher initial Cr(VI) concentrations, removal efficiencies (R-E) of the system with PAC were higher than R-E corresponding to the system without PAC. In addition, as the initial Cr(VI) concentration increased, the rate of Cr(VI) removal and R-E values decreased reflecting loss of metabolic activity of the activated sludge due to the toxicity of Cr(VI); however, this inhibition was less in systems with PAC. Whereas the removal of Cr(VI) using powdered activated carbon (PAC) alone is negligible, the addition of PAC can improve the biological reduction of Cr(VI) due to the stimulating or protective effect against the Cr(VI) toxicity. This protective effect was also observed in respiratory activity of the biomass.","Hexavalent chromium removal using aerobic activated sludge batch systems added with powdered activated carbon Abs: The addition of powdered activated carbon (PAC) has been proposed as a suitable technique to protect activated sludge against toxic wastewaters. However, the literature data describing the combined effect of PAC addition on Cr(VI) removal using activated sludge are scarce. The objectives of this study were to investigate the effect of the initial Cr(VI) concentration, PAC and an electron donor addition on Cr(VI) removal using aerobic activated sludge batch reactors. The following Cr(VI) removal systems were tested: activated sludge alone; activated sludge with an external electron donor (5 g/l of lactose); activated sludge with PAC addition (4 g/l); activated sludge with both PAC and lactose; and PAC alone. The results reported here showed that activated sludges are capable of removing Cr(VI) via its reduction to Cr(III) only if a suitable electron donor (such as lactose) is available. For initial Cr(VI) concentration lower than 10 mg/l, biomass alone can remove 100% of the Cr(VI). However, for higher initial Cr(VI) concentrations, removal efficiencies (R-E) of the system with PAC were higher than R-E corresponding to the system without PAC. In addition, as the initial Cr(VI) concentration increased, the rate of Cr(VI) removal and R-E values decreased reflecting loss of metabolic activity of the activated sludge due to the toxicity of Cr(VI); however, this inhibition was less in systems with PAC. Whereas the removal of Cr(VI) using powdered activated carbon (PAC) alone is negligible, the addition of PAC can improve the biological reduction of Cr(VI) due to the stimulating or protective effect against the Cr(VI) toxicity. This protective effect was also observed in respiratory activity of the biomass."
1578222,Opoka et al. 2011,APPLICABILITY OF THE SILVER AMALGAM ELECTRODE IN VOLTAMMETRIC DETERMINATION OF ZINC AND COPPER IN GASTRIC JUICE AND GASTRIC MUCOSA OF RATS,"The aim of the work was to compare two analytical methods of trace analysis in respect to their applicability in heavy metals determination in biological samples. Atomic absorption spectrometry (AAS) may be considered as the method of choice in such analyses due to its accuracy, precision and low detection limit. On the other hand, voltammetric methods seem to be as useful, but rarely applied. Having in mind that there is no universal analytical method, we have compared two AAS and voltammetric methods as the tools for Zn and Cu determination in the samples collected from rat gastric juice and gastric mucosa. Construction of the renewable silver amalgam film electrode (Hg(Ag)FE) for stripping voltammetry was described. Detailed optimization of measurements procedure and sample preparation for differential pulse anodic stripping voltammetry (DP ASV) and AAS were also performed and presented. The obtained results of quantitative analysis of the chosen parameters by means of both methods are discussed.","APPLICABILITY OF THE SILVER AMALGAM ELECTRODE IN VOLTAMMETRIC DETERMINATION OF ZINC AND COPPER IN GASTRIC JUICE AND GASTRIC MUCOSA OF RATS Abs: The aim of the work was to compare two analytical methods of trace analysis in respect to their applicability in heavy metals determination in biological samples. Atomic absorption spectrometry (AAS) may be considered as the method of choice in such analyses due to its accuracy, precision and low detection limit. On the other hand, voltammetric methods seem to be as useful, but rarely applied. Having in mind that there is no universal analytical method, we have compared two AAS and voltammetric methods as the tools for Zn and Cu determination in the samples collected from rat gastric juice and gastric mucosa. Construction of the renewable silver amalgam film electrode (Hg(Ag)FE) for stripping voltammetry was described. Detailed optimization of measurements procedure and sample preparation for differential pulse anodic stripping voltammetry (DP ASV) and AAS were also performed and presented. The obtained results of quantitative analysis of the chosen parameters by means of both methods are discussed."
1578219,Nozawa et al. 1998,Quantitative detection of Enterobacter cloacae strain HO-1 in bioreactor for chromate wastewater treatment using polymerase chain reaction (PCR),"BIOSIS COPYRIGHT: BIOL ABS. A novel method for the detection of specific microbes using the polymerase chain reaction (PCR) technique was developed and applied for the quantitative detection of Enterobacter cloacae strain HO-1 (HO-1, hereafter) in the experimental apparatus used for the treatment of wastewater containing hexavalent chromium (chromate). Note that HO-1 is capable of reducing toxic chromate to trivalent chromium. Based upon the preliminary experiments using pUC18 DNA, conditions giving a constant amplification rate of the targeted DNA with high reliability were determined for the quantitative detection of its initial concentration by the extrapolation. The cell density of HO-1 determined by the PCR technique was compared with the results counted on the selective medium agar plate conventionally used for the counting of HO-1. The procedure proposed here was successfully applied to estimate the cell density of Enterobacter cloacae HO-1 in the bioreactor for the treatment of chromate w","Quantitative detection of Enterobacter cloacae strain HO-1 in bioreactor for chromate wastewater treatment using polymerase chain reaction (PCR) Abs: BIOSIS COPYRIGHT: BIOL ABS. A novel method for the detection of specific microbes using the polymerase chain reaction (PCR) technique was developed and applied for the quantitative detection of Enterobacter cloacae strain HO-1 (HO-1, hereafter) in the experimental apparatus used for the treatment of wastewater containing hexavalent chromium (chromate). Note that HO-1 is capable of reducing toxic chromate to trivalent chromium. Based upon the preliminary experiments using pUC18 DNA, conditions giving a constant amplification rate of the targeted DNA with high reliability were determined for the quantitative detection of its initial concentration by the extrapolation. The cell density of HO-1 determined by the PCR technique was compared with the results counted on the selective medium agar plate conventionally used for the counting of HO-1. The procedure proposed here was successfully applied to estimate the cell density of Enterobacter cloacae HO-1 in the bioreactor for the treatment of chromate w"
1578218,Neuhauser et al. 1999,On-line monitoring of chromium aerosols in industrial exhaust streams by laser-induced plasma spectroscopy (LIPS),BIOSIS COPYRIGHT: BIOL ABS. Ultrafine heavy metal aerosols can have severe toxic and carcinogenic effects when inhaled in higher concentrations. The objective of this work was to develop a mobile continuous emission monitor (CEM) based on laser-induced plasma spectroscopy (LIPS) for an on-line analysis of chromium aerosols. The LIPS emission sensor was installed in an electroplating facility for a fast monitoring of particulate emissions to provide instantaneous feedback for process control. The prototype was tested in coo independent reference analysis.,On-line monitoring of chromium aerosols in industrial exhaust streams by laser-induced plasma spectroscopy (LIPS) Abs: BIOSIS COPYRIGHT: BIOL ABS. Ultrafine heavy metal aerosols can have severe toxic and carcinogenic effects when inhaled in higher concentrations. The objective of this work was to develop a mobile continuous emission monitor (CEM) based on laser-induced plasma spectroscopy (LIPS) for an on-line analysis of chromium aerosols. The LIPS emission sensor was installed in an electroplating facility for a fast monitoring of particulate emissions to provide instantaneous feedback for process control. The prototype was tested in coo independent reference analysis.
1578216,Nasalska and  Skompska 2003,"Removal of toxic chromate ions by the films of poly(1,8-diaminonaphthalene)","Poly(1,8-diaminonaphthalene) films, p(1,8-DAN), were electrosynthesized on a Pt electrode to study their utility in extracting Cr(VI) ( as dichromate ions) from acidic aqueous solution. The electrodeposition procedure was improved by acidification of the acetonitrile electropolymerisation bath with CCl(3)COOH. Possible molecular structures of electrosynthesized poly(1,8-diaminonaphthalene) were determined by means of IR spectroscopy. The mechanism of dichromate ion removal was studied by potentiometric measurements in the system Ag/AgCl/Cl((std))(-)/0.1 M HClO(4)/ p(1,8-DAN)/Pt, upon addition of K(2)Cr(2)O(7) solution. The presence and oxidation state of chromium in the polymer matrix was explored by means of energy dispersive X-ray (EDX) spectrometry.","Removal of toxic chromate ions by the films of poly(1,8-diaminonaphthalene) Abs: Poly(1,8-diaminonaphthalene) films, p(1,8-DAN), were electrosynthesized on a Pt electrode to study their utility in extracting Cr(VI) ( as dichromate ions) from acidic aqueous solution. The electrodeposition procedure was improved by acidification of the acetonitrile electropolymerisation bath with CCl(3)COOH. Possible molecular structures of electrosynthesized poly(1,8-diaminonaphthalene) were determined by means of IR spectroscopy. The mechanism of dichromate ion removal was studied by potentiometric measurements in the system Ag/AgCl/Cl((std))(-)/0.1 M HClO(4)/ p(1,8-DAN)/Pt, upon addition of K(2)Cr(2)O(7) solution. The presence and oxidation state of chromium in the polymer matrix was explored by means of energy dispersive X-ray (EDX) spectrometry."
1578215,Nam et al. 2001,Direct measurement of trivalent chromium and hexavalent chromium by ion chromatography coupled with end-on-view ICP-AES,"Chemical speciation of trace elements in environmental samples can be very important. Chromium (III), for example, is an essential nutrient for humans, but chromium (VI) is toxic. Accordingly any analysis of chromium must be able to distinguish and quantitate the two forms. A highly sensitive method for this analysis is described here involving a separation step using ion chromatography followed by ICP-AES for detection.","Direct measurement of trivalent chromium and hexavalent chromium by ion chromatography coupled with end-on-view ICP-AES Abs: Chemical speciation of trace elements in environmental samples can be very important. Chromium (III), for example, is an essential nutrient for humans, but chromium (VI) is toxic. Accordingly any analysis of chromium must be able to distinguish and quantitate the two forms. A highly sensitive method for this analysis is described here involving a separation step using ion chromatography followed by ICP-AES for detection."
1578206,Nam et al. 2003,Direct determination of Se(IV) and Se(VI) by ion chromatography combined with end-on view inductively coupled plasma atomic emission spectrometry,"Selenium is essential in small amounts in the human diet but is toxic in large amounts. Moreover, its toxicity depends on the chemical form of the element. Accordingly, species determination is necessary in any environmental analysis. A highly sensitive procedure is described in this article that combines separation of the oxidation states of the element by ion chromatography with detection by plasma AES.","Direct determination of Se(IV) and Se(VI) by ion chromatography combined with end-on view inductively coupled plasma atomic emission spectrometry Abs: Selenium is essential in small amounts in the human diet but is toxic in large amounts. Moreover, its toxicity depends on the chemical form of the element. Accordingly, species determination is necessary in any environmental analysis. A highly sensitive procedure is described in this article that combines separation of the oxidation states of the element by ion chromatography with detection by plasma AES."
1578205,Muneer et al. 2007,Chromium resistant yeast with multi-metal resistance isolated from industrial effluents and their possible use in microbial consortium for bioremediation of wastewater,"Chromium (Cr) resistant yeasts with minimum inhibitory concentration of Cr6+ of 2.0 mg/mL were isolated from industrial effluents of tanneries, which could also tolerate 1.0-1.3 mg/mL of Pb2+ 0.6-0.8 mg/mL of Cd2+ and Cu2+, 0.4-0.5 mg/mL of Co2+, 0.3-0.6 mg/mL of Ni2+ 0.2 mg/mL of Hg2+ and 0.3-0.5 mg/mL of Zn2+. The isolates showed optimum growth at 30 degrees C and pH 5.5-6.0. All yeast isolates showed typical growth pattern except for the lag phase which got extended in the presence of Cr. The yeast isolates could remove 65-80% of Cr6+ from the medium after 72 hours of incubation. The yeast isolates absorbed 25-35% of Cr6+ whereas 30-40% of the Cr6+ was adsorbed on the cell surface. The yeast isolates can be exploited for bioremediation of chromium containing wastes, since they seem to have the potential to accumulate the toxic metal from the environment.","Chromium resistant yeast with multi-metal resistance isolated from industrial effluents and their possible use in microbial consortium for bioremediation of wastewater Abs: Chromium (Cr) resistant yeasts with minimum inhibitory concentration of Cr6+ of 2.0 mg/mL were isolated from industrial effluents of tanneries, which could also tolerate 1.0-1.3 mg/mL of Pb2+ 0.6-0.8 mg/mL of Cd2+ and Cu2+, 0.4-0.5 mg/mL of Co2+, 0.3-0.6 mg/mL of Ni2+ 0.2 mg/mL of Hg2+ and 0.3-0.5 mg/mL of Zn2+. The isolates showed optimum growth at 30 degrees C and pH 5.5-6.0. All yeast isolates showed typical growth pattern except for the lag phase which got extended in the presence of Cr. The yeast isolates could remove 65-80% of Cr6+ from the medium after 72 hours of incubation. The yeast isolates absorbed 25-35% of Cr6+ whereas 30-40% of the Cr6+ was adsorbed on the cell surface. The yeast isolates can be exploited for bioremediation of chromium containing wastes, since they seem to have the potential to accumulate the toxic metal from the environment."
1578204,Mughal et al. 2008,Treatment of electroplating effluent,"Effluent samples were collected from electroplating industry at Kot lakhpat Lahore. The samples were physically and chemically analyzed for different parameters and metals concentrations. The concentrations of all metals including chromium, cadmium, nickel, manganese and iron were higher than threshold limit. Chromium is environmentally hazardous and carcinogenic. The electroplating effluent with high Chromium concentration has been treated through chemical precipitation (CP). The treatment of chromium is pH dependent. The experiment results showed that CP process has successfully eliminated chromium from electroplating effluent. The percentage removal is 95 % chromium leaving less than 0.10mg/L Cr(VI) in filtrate.","Treatment of electroplating effluent Abs: Effluent samples were collected from electroplating industry at Kot lakhpat Lahore. The samples were physically and chemically analyzed for different parameters and metals concentrations. The concentrations of all metals including chromium, cadmium, nickel, manganese and iron were higher than threshold limit. Chromium is environmentally hazardous and carcinogenic. The electroplating effluent with high Chromium concentration has been treated through chemical precipitation (CP). The treatment of chromium is pH dependent. The experiment results showed that CP process has successfully eliminated chromium from electroplating effluent. The percentage removal is 95 % chromium leaving less than 0.10mg/L Cr(VI) in filtrate."
1578203,Moutarlier et al. 2001,Electrochemical characterisation of anodic oxidation films formed in presence of corrosion inhibitors,"Most oxide films provide extensive corrosion inhibitors by incorporation of chromium compounds (i.e. Cr(VI)) that provide such good protection. But, replacement of hexavalent chromium is also under active consideration because of its toxicity. This paper describes research, which has been carried out to find alternatives to chromic acid anodisation (H2CrO4), for 2024-aluminium alloy. Promising inhibitors: molybdate and permanganate anions have been identified. In this work, attempts have been made to incorporate these inhibitors into the anodic film during the anodising process. Corrosion performance has been studied and compared using anodic polarisation techniques and impedance spectrometry measurements. (C) 2001 Elsevier Science B.V. All rights reserved.","Electrochemical characterisation of anodic oxidation films formed in presence of corrosion inhibitors Abs: Most oxide films provide extensive corrosion inhibitors by incorporation of chromium compounds (i.e. Cr(VI)) that provide such good protection. But, replacement of hexavalent chromium is also under active consideration because of its toxicity. This paper describes research, which has been carried out to find alternatives to chromic acid anodisation (H2CrO4), for 2024-aluminium alloy. Promising inhibitors: molybdate and permanganate anions have been identified. In this work, attempts have been made to incorporate these inhibitors into the anodic film during the anodising process. Corrosion performance has been studied and compared using anodic polarisation techniques and impedance spectrometry measurements. (C) 2001 Elsevier Science B.V. All rights reserved."
1578202,Moriki and  Karydis 1996,A laboratory phytoplankton microcosm for the assessment of metal impacts in the marine environment,"The toxicity of Chromium (VI) in marine phytoplanktonic communities has been evaluated with four microcosms of natural phytoplankton populations. Photosynthetic pigments, carbohydrates, dissolved organic matter, cell number and species composition were the main parameters recorded as a measure of community response to stress. The sensitivity of several ecological indices was evaluated for the assessment of the toxic impacts of the metal. The use of biological indices in metal toxicity testing and the advantages of laboratory community studies in the assessment of environmental impacts are discussed.","A laboratory phytoplankton microcosm for the assessment of metal impacts in the marine environment Abs: The toxicity of Chromium (VI) in marine phytoplanktonic communities has been evaluated with four microcosms of natural phytoplankton populations. Photosynthetic pigments, carbohydrates, dissolved organic matter, cell number and species composition were the main parameters recorded as a measure of community response to stress. The sensitivity of several ecological indices was evaluated for the assessment of the toxic impacts of the metal. The use of biological indices in metal toxicity testing and the advantages of laboratory community studies in the assessment of environmental impacts are discussed."
1578201,Morales-Barrera et al. 2010,"ISOLATION, IDENTIFICATION AND CHARACTERIZATION OF A Fusarium lichenicola STRAIN WITH HIGH Cr(VI) REDUCTION POTENTIAL","A fungal strain with high Cr(VI) reduction potential was isolated from a heavy metal-contaminated soil by batch enrichment culture techniques. The isolated fungus was identified as Fusarium lichenicola by the D1/D2 domain sequence of its 28S rDNA gene. The Cr(VI) reduction process catalyzed by F. lichenicola was characterized in batch cultures conducted at initial Cr(VI) concentrations ranging from 0.56 to 3.63 mM. The fungus showed remarkable capacity to reduce very high concentrations of Cr(VI) (2.89 mM) completely, under aerobic conditions. The highest volumetric rate of Cr(VI) reduction was approximately I mg L(-1) h(-1) and it was attained at initial Cr(VI) concentrations ranging from 0.56 to 2.06 mM; however, at higher Cr(VI) concentrations, the volumetric rate decreased, probably due to Cr(VI) toxicity. The characteristics exhibited by this F. lichenicola strain make it potentially useful in biotechnological processes for remediation of Cr(VI)-laden wastewaters.","ISOLATION, IDENTIFICATION AND CHARACTERIZATION OF A Fusarium lichenicola STRAIN WITH HIGH Cr(VI) REDUCTION POTENTIAL Abs: A fungal strain with high Cr(VI) reduction potential was isolated from a heavy metal-contaminated soil by batch enrichment culture techniques. The isolated fungus was identified as Fusarium lichenicola by the D1/D2 domain sequence of its 28S rDNA gene. The Cr(VI) reduction process catalyzed by F. lichenicola was characterized in batch cultures conducted at initial Cr(VI) concentrations ranging from 0.56 to 3.63 mM. The fungus showed remarkable capacity to reduce very high concentrations of Cr(VI) (2.89 mM) completely, under aerobic conditions. The highest volumetric rate of Cr(VI) reduction was approximately I mg L(-1) h(-1) and it was attained at initial Cr(VI) concentrations ranging from 0.56 to 2.06 mM; however, at higher Cr(VI) concentrations, the volumetric rate decreased, probably due to Cr(VI) toxicity. The characteristics exhibited by this F. lichenicola strain make it potentially useful in biotechnological processes for remediation of Cr(VI)-laden wastewaters."
1578200,Mondal et al. 2001,Micellar effect on the reaction of chromium(VI) oxidation of formaldehyde in the presence and absence of picolinic acid in aqueous acid media: A kinetic study,"The kinetics and mechanism of Cr(VI) oxidation of formaldehyde in the presence and absence of picolinic acid (PA) in aqueous acid media have been carried out under the conditions, [formaldehyde](r) much greater than [Cr(VI)IT at different temperatures. Under the kinetic conditions, the monomeric species of Cr(VI) has been found kinetically active in the absence of PA while in the PA catalysed path, Cr(VI)-PA complex has been suggested as the active oxidant. In the PA catalysed path, Cr(VI)-PA complex receives a nucleophilic attack by the substrate to form a ternary complex which subsequently experiences a redox decomposition (through 2e transfer) leading to formic acid and Cr(IV)-PA complex. Then Cr(IV)-PA complex participates further in the oxidation of formaldehyde and ultimately is converted into Cr(III)-PA complex. In the uncatalysed path, Cr(VI)-substrate ester experiences an acid catalysed redox decomposition (2e transfer) at the rate determining step. The uncatalysed path shows a second order dependence on [H+] while the PA catalysed path shows a zeroth order dependence on [H+]. Both the uncatalysed and PA catalysed paths show first-order dependence on [formaldehyde]T and [Cr(VI)](r). The PA catalysed path is first order in [PA]T. All these observations (i.e. dependence patterns on the reactants) remain unaltered in the presence of externally added surfactants. Effect of cationic surfactant (i.e. cetylpyridinium chloride. CPC) and anionic surfactant tie. sodium dodecyl sulphate, SDS) has been studied both in the presence and absence of PA. CPC inhibits the reactions while SDS catalyses the reactions. The observed micellar effects have been explained by considering the partitioning of the reactants between the micellar and aqueous phase. Applicability of different kinetic models, e.g. pseudo-phase ion exchange (PIE) model, Menger-Portnoy model, Piszkiewicz cooperative model, has been tested to explain the observed micellar effects.","Micellar effect on the reaction of chromium(VI) oxidation of formaldehyde in the presence and absence of picolinic acid in aqueous acid media: A kinetic study Abs: The kinetics and mechanism of Cr(VI) oxidation of formaldehyde in the presence and absence of picolinic acid (PA) in aqueous acid media have been carried out under the conditions, [formaldehyde](r) much greater than [Cr(VI)IT at different temperatures. Under the kinetic conditions, the monomeric species of Cr(VI) has been found kinetically active in the absence of PA while in the PA catalysed path, Cr(VI)-PA complex has been suggested as the active oxidant. In the PA catalysed path, Cr(VI)-PA complex receives a nucleophilic attack by the substrate to form a ternary complex which subsequently experiences a redox decomposition (through 2e transfer) leading to formic acid and Cr(IV)-PA complex. Then Cr(IV)-PA complex participates further in the oxidation of formaldehyde and ultimately is converted into Cr(III)-PA complex. In the uncatalysed path, Cr(VI)-substrate ester experiences an acid catalysed redox decomposition (2e transfer) at the rate determining step. The uncatalysed path shows a second order dependence on [H+] while the PA catalysed path shows a zeroth order dependence on [H+]. Both the uncatalysed and PA catalysed paths show first-order dependence on [formaldehyde]T and [Cr(VI)](r). The PA catalysed path is first order in [PA]T. All these observations (i.e. dependence patterns on the reactants) remain unaltered in the presence of externally added surfactants. Effect of cationic surfactant (i.e. cetylpyridinium chloride. CPC) and anionic surfactant tie. sodium dodecyl sulphate, SDS) has been studied both in the presence and absence of PA. CPC inhibits the reactions while SDS catalyses the reactions. The observed micellar effects have been explained by considering the partitioning of the reactants between the micellar and aqueous phase. Applicability of different kinetic models, e.g. pseudo-phase ion exchange (PIE) model, Menger-Portnoy model, Piszkiewicz cooperative model, has been tested to explain the observed micellar effects."
1578199,Molto et al. 1995,USE OF INTRACAVITARY INTERFERON-ALPHA-2B IN THE PROPHYLACTIC TREATMENT OF PATIENTS WITH SUPERFICIAL BLADDER-CANCER,"Background. The evolution of superficial transitional cell carcinoma (TCC) of the bladder poses a clinical management problem due to its tendency to recur after initial transurethral resection (TUR). Natural Killer (NK) cells are a distinct subset of lymphocytes that possess the ability to lyse tumor cells without prior sensitization in a nonmajor histocompatibility-restricted fashion. These cytotoxic cells constitute a relevant barrier against the local growth and systemic dissemination of neoplastic diseases. Methods. The immunomodulatory effect, after TUR of the tumor, of the prophylactic treatment with intravesical instillations of interferon-alpha-2b (IFN-alpha-2b) upon the NK activity of peripheral blood mononuclear cells (PBMNC) in 17 patients with superficial TCC of the bladder was analyzed using a 4-hour (51)sodium chromate (Cr-51)-release cytotoxicity assay against both NK-sensitive, or K562, and NK-resistant, or JY, tumor target cells. Results. There were no significant modifications of the NK activity of PBMNC during the 3 months of IFN-alpha-2b intracavitary treatment (P > 0.05). However, with respect to their levels before treatment, NK activity in PBMNC at 3 months posttreatment was enhanced significantly in the 14 patients who showed no sign of tumor recurrence in the 12 months of follow-up (P < 0.01). Six months after finishing the intracavitary IFN-alpha-2b instillations, the PBMNC NK activity in these patients had returned to the levels found before initiating the therapy (P > 0.05). This temporary enhancement of the PBMNC NK activity was not found in three patients with evidence of tumor recurrence at some time during the 12 months after treatment. In similar experimental conditions, significant enhancement of the NK activity in PBMNC was not observed in nine patients with superficial bladder TCC who were treated with intracavitary instillations of mitomycin C (MMC) after the TUR of the tumor and who were free of recurrence of the disease at 1 year of follow up. Conclusion. The prophylactic intracavitary treatment of superficial bladder TCC with IFN-alpha-2b may induce an immunomodulatory effect in the NK activity of PBMNC that appears to be associated with the clinical evolution of the disease.","USE OF INTRACAVITARY INTERFERON-ALPHA-2B IN THE PROPHYLACTIC TREATMENT OF PATIENTS WITH SUPERFICIAL BLADDER-CANCER Abs: Background. The evolution of superficial transitional cell carcinoma (TCC) of the bladder poses a clinical management problem due to its tendency to recur after initial transurethral resection (TUR). Natural Killer (NK) cells are a distinct subset of lymphocytes that possess the ability to lyse tumor cells without prior sensitization in a nonmajor histocompatibility-restricted fashion. These cytotoxic cells constitute a relevant barrier against the local growth and systemic dissemination of neoplastic diseases. Methods. The immunomodulatory effect, after TUR of the tumor, of the prophylactic treatment with intravesical instillations of interferon-alpha-2b (IFN-alpha-2b) upon the NK activity of peripheral blood mononuclear cells (PBMNC) in 17 patients with superficial TCC of the bladder was analyzed using a 4-hour (51)sodium chromate (Cr-51)-release cytotoxicity assay against both NK-sensitive, or K562, and NK-resistant, or JY, tumor target cells. Results. There were no significant modifications of the NK activity of PBMNC during the 3 months of IFN-alpha-2b intracavitary treatment (P > 0.05). However, with respect to their levels before treatment, NK activity in PBMNC at 3 months posttreatment was enhanced significantly in the 14 patients who showed no sign of tumor recurrence in the 12 months of follow-up (P < 0.01). Six months after finishing the intracavitary IFN-alpha-2b instillations, the PBMNC NK activity in these patients had returned to the levels found before initiating the therapy (P > 0.05). This temporary enhancement of the PBMNC NK activity was not found in three patients with evidence of tumor recurrence at some time during the 12 months after treatment. In similar experimental conditions, significant enhancement of the NK activity in PBMNC was not observed in nine patients with superficial bladder TCC who were treated with intracavitary instillations of mitomycin C (MMC) after the TUR of the tumor and who were free of recurrence of the disease at 1 year of follow up. Conclusion. The prophylactic intracavitary treatment of superficial bladder TCC with IFN-alpha-2b may induce an immunomodulatory effect in the NK activity of PBMNC that appears to be associated with the clinical evolution of the disease."
1578198,Mishra 2003,Removal of chromium(VI) from aqueous solution using low cost adsorbent,"Column packed with tea leaves as adsorbent have been used for the removal of some toxic heavy metal ions from aqueous solutions. Breakthrough behaviour of Cr-VI on tea leaves has been studied. The effect of pH, concentration, flow rate on breakthrough capacity and effect of other diverse metal ions have been investigated. It has been observed that removal of Cr-VI is maximum at a pH value of 3.","Removal of chromium(VI) from aqueous solution using low cost adsorbent Abs: Column packed with tea leaves as adsorbent have been used for the removal of some toxic heavy metal ions from aqueous solutions. Breakthrough behaviour of Cr-VI on tea leaves has been studied. The effect of pH, concentration, flow rate on breakthrough capacity and effect of other diverse metal ions have been investigated. It has been observed that removal of Cr-VI is maximum at a pH value of 3."
1578197,Mise and  Shantha 1993,ADSORPTION STUDIES OF CHROMIUM(VI) FROM SYNTHETIC AQUEOUS-SOLUTION BY ACTIVATED CARBON DERIVED FROM BAGASSE,"The removal of chromium (VI) from synthetic waste water by adsorption on activated carbon prepared from Bagasse (solid waste produced by sugar industries) was tried to determine the effects of different dosages and different pH. The removal of chromium (VI) from synthetic waste water by adsorption on two types of activated carbon, physical activation and chemical activation (CaCl2 & MgCl2), IRs 0.25, 0.5, 0.75, different pH and different dosages was studied. It was observed that as dosage increases the adsorption increased along with the increase in IR. It was also noted as IR increases the surface area of Bagasse carbon increased. These dosage data were considered in the construction of isotherms. And it was found adsorption follows Freundlich, Langmuir and BET isotherms. The maximum removal of chromium (VI) is obtained at pH 2.0.","ADSORPTION STUDIES OF CHROMIUM(VI) FROM SYNTHETIC AQUEOUS-SOLUTION BY ACTIVATED CARBON DERIVED FROM BAGASSE Abs: The removal of chromium (VI) from synthetic waste water by adsorption on activated carbon prepared from Bagasse (solid waste produced by sugar industries) was tried to determine the effects of different dosages and different pH. The removal of chromium (VI) from synthetic waste water by adsorption on two types of activated carbon, physical activation and chemical activation (CaCl2 & MgCl2), IRs 0.25, 0.5, 0.75, different pH and different dosages was studied. It was observed that as dosage increases the adsorption increased along with the increase in IR. It was also noted as IR increases the surface area of Bagasse carbon increased. These dosage data were considered in the construction of isotherms. And it was found adsorption follows Freundlich, Langmuir and BET isotherms. The maximum removal of chromium (VI) is obtained at pH 2.0."
1578196,Milacic et al. 1992,FRACTIONATION OF CR AND DETERMINATION OF CR(VI) IN BLUE SHAVINGS,"Blue shavings are a protein-based matrix with a high content of chromium(III) salts and organic polymers. If they contain excessive amounts of chromium(VI) they could be a potentially hazardous waste in the environment. Fractionation of chromium in blue shavings was studied by employing various sequential extraction procedures to determine the water soluble, exchangeable, organically bound, carbonate, crystalline, hydroxide and sulphide fractions. Chromium(VI) was determined in the phosphate buffer extractable (pH = 6.5 - 7.0) fraction. Results obtained by several analytical techniques indicate limitations in the determination of Cr(VI). Ion-pairing reversed phase HPLC combined with flame or electrothermal AAS was found to be affected by severe matrix effects due to organic polymers in blue shavings and high salt concentrations in the buffer and extractant solutions. Chelating ion-exchange and ion-exchange chromatography combined with flame AAS detection gave over-estimated results due to inefficient retention of inert Cr(III) complexes. Spectrophotometry (addition of diphenylcarbazide reagent to the analyte prior to acidification) and extraction of Cr(VI)-HC1 complex into MIBK (277 K) gave generally comparable and reliable results. The detection limit for the former technique was 2 ng cm-3 and 15 ng cm-3 for the latter. Our investigations indicate that over 90 percent of total chromium in blue shavings is in chemically inert forms, approximately 8 percent is extracted with Na4P2O7 while less than 0.003 percent exists in the toxic chromate form.","FRACTIONATION OF CR AND DETERMINATION OF CR(VI) IN BLUE SHAVINGS Abs: Blue shavings are a protein-based matrix with a high content of chromium(III) salts and organic polymers. If they contain excessive amounts of chromium(VI) they could be a potentially hazardous waste in the environment. Fractionation of chromium in blue shavings was studied by employing various sequential extraction procedures to determine the water soluble, exchangeable, organically bound, carbonate, crystalline, hydroxide and sulphide fractions. Chromium(VI) was determined in the phosphate buffer extractable (pH = 6.5 - 7.0) fraction. Results obtained by several analytical techniques indicate limitations in the determination of Cr(VI). Ion-pairing reversed phase HPLC combined with flame or electrothermal AAS was found to be affected by severe matrix effects due to organic polymers in blue shavings and high salt concentrations in the buffer and extractant solutions. Chelating ion-exchange and ion-exchange chromatography combined with flame AAS detection gave over-estimated results due to inefficient retention of inert Cr(III) complexes. Spectrophotometry (addition of diphenylcarbazide reagent to the analyte prior to acidification) and extraction of Cr(VI)-HC1 complex into MIBK (277 K) gave generally comparable and reliable results. The detection limit for the former technique was 2 ng cm-3 and 15 ng cm-3 for the latter. Our investigations indicate that over 90 percent of total chromium in blue shavings is in chemically inert forms, approximately 8 percent is extracted with Na4P2O7 while less than 0.003 percent exists in the toxic chromate form."
1578195,Michalski 2005,Comparison of the analytical performance of two columns used for determination of chromium(VI) in water,"In the different compartments of the environmental chromium occurs mainly in the oxidation states (III) and (VI). Although Cr(III) is an essential trace element for humans, Cr(VI) is highly cancerogenic and mutagenic. It is, therefore, necessary for risk assessment not only to determine total chromium, but also to determine chromium species, especially Cr(VI). Hexavalent chromium can be determined as chromate (CrO42-) by ion chromatography. In recent years ion chromatography has became a powerful technique for determination of ions, including inorganic and organic anions and cations. In the work discussed in this paper an ion-chromatographic method using ion-exchange columns and direct UV detection for determination of Cr(VI) in water samples has been validated. The analytical performance of Dionex IonPac AS7 and CS5A columns has been compared and method linearity and sensitivity, limit of determination, and limit of quantification calculated from peak area and peak height are given.","Comparison of the analytical performance of two columns used for determination of chromium(VI) in water Abs: In the different compartments of the environmental chromium occurs mainly in the oxidation states (III) and (VI). Although Cr(III) is an essential trace element for humans, Cr(VI) is highly cancerogenic and mutagenic. It is, therefore, necessary for risk assessment not only to determine total chromium, but also to determine chromium species, especially Cr(VI). Hexavalent chromium can be determined as chromate (CrO42-) by ion chromatography. In recent years ion chromatography has became a powerful technique for determination of ions, including inorganic and organic anions and cations. In the work discussed in this paper an ion-chromatographic method using ion-exchange columns and direct UV detection for determination of Cr(VI) in water samples has been validated. The analytical performance of Dionex IonPac AS7 and CS5A columns has been compared and method linearity and sensitivity, limit of determination, and limit of quantification calculated from peak area and peak height are given."
1578194,Michalski 2004,Ion chromatography method for the determination of trace levels of chromium(VI) in water,"Chromium exists usually in the (III) or (VI) oxidation states. In contrast to Cr(III), which is essential to mammalian systems, Cr(VI) is dangerous for humans due to its toxicity and carcinogenic properties. Cr(VI) compounds are highly soluble, mobile and bioavailable compared to Cr(III) species. Chromium is usually analyzed using instrumental methods such as AAS or ICP, which are accurate and sensitive, but allow determination of only the total content of chromium in a sample. Determination of Cr(VI) still represents a formidable challenge in analytical chemistry. This paper describes sensitive and selective determination of Cr(VI) in water samples on mug L-1 levels using an ion chromatography system with UV detector, without any sample preconcentration method. The detection limits achieved were less than 0.1 mug L-1 in deonized water and 0.2 mug L-1 in rainwater and drinking water, respectively. The method was applied to determination of Cr(VI) in rainwater and water extracts from galvanic sediments.","Ion chromatography method for the determination of trace levels of chromium(VI) in water Abs: Chromium exists usually in the (III) or (VI) oxidation states. In contrast to Cr(III), which is essential to mammalian systems, Cr(VI) is dangerous for humans due to its toxicity and carcinogenic properties. Cr(VI) compounds are highly soluble, mobile and bioavailable compared to Cr(III) species. Chromium is usually analyzed using instrumental methods such as AAS or ICP, which are accurate and sensitive, but allow determination of only the total content of chromium in a sample. Determination of Cr(VI) still represents a formidable challenge in analytical chemistry. This paper describes sensitive and selective determination of Cr(VI) in water samples on mug L-1 levels using an ion chromatography system with UV detector, without any sample preconcentration method. The detection limits achieved were less than 0.1 mug L-1 in deonized water and 0.2 mug L-1 in rainwater and drinking water, respectively. The method was applied to determination of Cr(VI) in rainwater and water extracts from galvanic sediments."
1578193,Meena and  Rajagopal 2003,Comparative studies on adsorptive removal of chromium from contaminated water using different adsorbents,"Chromium, especially the hexavalent form, is toxic to humans. Industries like chrome plating, textile, electroplating discharge Cr(VI) in their effluents. Wastes containing chromium are environmentally persistent and toxic, and cannot be degraded or detoxified biologically. Various techniques developed for the removal of heavy metals include chemical precipitation, ion exchange and adsorption. Activated carbon adsorption systems though widely used are very expensive and the regeneration cost is also very high. Therefore, their use in wastewater treatment may not be economically feasible. There is, therefore, a need to identify and study adsorptive characteristics of low cost alternatives. The present investigation was, therefore, undertaken to select suit-able locally and commercially available adsorbents such as activated alumina, ion exchange resin, with special attention to low cost adsorbents like saw dust, treated saw dust and sand, and to carry out a comparative study of their applicability to heavy metal removal. The results of these studies are presented in this paper.","Comparative studies on adsorptive removal of chromium from contaminated water using different adsorbents Abs: Chromium, especially the hexavalent form, is toxic to humans. Industries like chrome plating, textile, electroplating discharge Cr(VI) in their effluents. Wastes containing chromium are environmentally persistent and toxic, and cannot be degraded or detoxified biologically. Various techniques developed for the removal of heavy metals include chemical precipitation, ion exchange and adsorption. Activated carbon adsorption systems though widely used are very expensive and the regeneration cost is also very high. Therefore, their use in wastewater treatment may not be economically feasible. There is, therefore, a need to identify and study adsorptive characteristics of low cost alternatives. The present investigation was, therefore, undertaken to select suit-able locally and commercially available adsorbents such as activated alumina, ion exchange resin, with special attention to low cost adsorbents like saw dust, treated saw dust and sand, and to carry out a comparative study of their applicability to heavy metal removal. The results of these studies are presented in this paper."
1578192,Matsumoto et al. 2006,"Genotoxicity and mutagenicity of water contaminated with tannery effluents, as evaluated by the micronucleus test and comet assay using the fish Oreochromis niloticus and chromosome aberrations in onion root-tips","Cytotoxicity of metals is important because some metals are potential mutagens able to induce tumors in humans and experimental animals. Chromium can damage DNA in several ways, including DNA double strand breaks (DSBs) which generate chromosomal aberrations, micronucleus formation, sister chromatid exchange, formation of DNA adducts and alterations in DNA replication and transcription. In our study, water samples from three sites in the Corrego dos Bagres stream in the Franca municipality of the Brazilian state of Sao Paulo were subjected to the comet assay and micronucleus test using erythrocytes from the fish Oreochromis niloticus. Nuclear abnormalities of the erythrocytes included blebbed, notched and lobed nuclei, probably due to genotoxic chromium compounds. The greatest comet assay damage occurred with water from a chromium-containing tannery effluent discharge site, supporting the hypothesis that chromium residues can be genotoxic. The mutagenicity of the water samples was assessed using the onion root-tip cell assay, the most frequent chromosomal abnormalities observed being: c-metaphases, stick chromosome, chromosome breaks and losses, bridged anaphases, multipolar anaphases, and micronucleated and binucleated cells. Onion root-tip cell mutagenicity was highest for water samples containing the highest levels of chromium.","Genotoxicity and mutagenicity of water contaminated with tannery effluents, as evaluated by the micronucleus test and comet assay using the fish Oreochromis niloticus and chromosome aberrations in onion root-tips Abs: Cytotoxicity of metals is important because some metals are potential mutagens able to induce tumors in humans and experimental animals. Chromium can damage DNA in several ways, including DNA double strand breaks (DSBs) which generate chromosomal aberrations, micronucleus formation, sister chromatid exchange, formation of DNA adducts and alterations in DNA replication and transcription. In our study, water samples from three sites in the Corrego dos Bagres stream in the Franca municipality of the Brazilian state of Sao Paulo were subjected to the comet assay and micronucleus test using erythrocytes from the fish Oreochromis niloticus. Nuclear abnormalities of the erythrocytes included blebbed, notched and lobed nuclei, probably due to genotoxic chromium compounds. The greatest comet assay damage occurred with water from a chromium-containing tannery effluent discharge site, supporting the hypothesis that chromium residues can be genotoxic. The mutagenicity of the water samples was assessed using the onion root-tip cell assay, the most frequent chromosomal abnormalities observed being: c-metaphases, stick chromosome, chromosome breaks and losses, bridged anaphases, multipolar anaphases, and micronucleated and binucleated cells. Onion root-tip cell mutagenicity was highest for water samples containing the highest levels of chromium."
1578191,Marmer 1996,Preservation and tanning of animal hides - The making of leather and its investigation by the US department of agriculture,"Animal hides are the most valuable co-product of the packing industry. They are a renewable resource of great export value, raw or tanned. Much of the current research in hides and leather researach at the Eastern Regional Research Center (ERRC) addresses environmental issues of the packing and tanning industries. Hides are traditionally preserved in NaCl brine. Research has focused on damage from halophiles and on alternatives to NaCl brine, e.g., KCI brine or electron-beam irradiation. Pretanning steps, chemical and enzymatic, essentially leave a matrix of collagen-I. New methodology allows assay of bating enzyme activity during one such step. About 90% of all hides are tanned with Cr-III salts, and though the resulting product is not regarded as toxic, the toxicity of Cr-VI species raises public concern over all Cr-containing material. This has spurred a quest for alternatives both to chrome tanning and to disposal of huge amounts of solid, chrome-containing tannery waste. We have developed a molecular model of collagen-I to assist our understanding of the mechanism of chrome tanning and organic crosslinking, and we now can process the solid waste into chrome-free protein fractions and recyclable chromium oxide. The final steps of leather production involve physical and chemical finishing. Chemical and physical softening has been studied by acoustic emission. UV-cured finishes were demonstrated as alternatives to solvent-based spray finishes.","Preservation and tanning of animal hides - The making of leather and its investigation by the US department of agriculture Abs: Animal hides are the most valuable co-product of the packing industry. They are a renewable resource of great export value, raw or tanned. Much of the current research in hides and leather researach at the Eastern Regional Research Center (ERRC) addresses environmental issues of the packing and tanning industries. Hides are traditionally preserved in NaCl brine. Research has focused on damage from halophiles and on alternatives to NaCl brine, e.g., KCI brine or electron-beam irradiation. Pretanning steps, chemical and enzymatic, essentially leave a matrix of collagen-I. New methodology allows assay of bating enzyme activity during one such step. About 90% of all hides are tanned with Cr-III salts, and though the resulting product is not regarded as toxic, the toxicity of Cr-VI species raises public concern over all Cr-containing material. This has spurred a quest for alternatives both to chrome tanning and to disposal of huge amounts of solid, chrome-containing tannery waste. We have developed a molecular model of collagen-I to assist our understanding of the mechanism of chrome tanning and organic crosslinking, and we now can process the solid waste into chrome-free protein fractions and recyclable chromium oxide. The final steps of leather production involve physical and chemical finishing. Chemical and physical softening has been studied by acoustic emission. UV-cured finishes were demonstrated as alternatives to solvent-based spray finishes."
1578189,Madrakian et al. 2009,Application of Organized Media for Rapid Spectrofluorimetric Determination of Trace Amounts of Cr(VI) in the Presence of Cr(III),"A simple, selective and sensitive fluorescence quenching method was developed to the determination Cr(VI). The method is based on the oxidation of I(-) to I(3)(-) by Cr(VI) in sulfuric acid solution followed by immediate formation of ion association compound between I(3)(-) and rhodamine 6G in Tween-80 micellar media at room temperature. The influence of several surfactants on rhodamine 6G fluorescence signal was studied; particular attention was paid in the aggregation behavior of rhodamine 6G-Tween-80 system. The experimental parameters (e.g., type of surfactant, reagent concentration) were Studied and the optimal conditions were established. The linear calibration graph was obtained in the range 2.0 - 100.0 ng mL(-1) Cr(VI). The detection limit of the method was 0.37 ng mL(-1). The relative standard deviation (R.S.D.) is less than 5% (n = 5). The efficiency of the method for the determination of Cr(VI) in the presence of Cr(III) in the sample was investigated. The method was applied successfully to the determination of Cr(VI) and total Cr in water, and liver tissue samples.","Application of Organized Media for Rapid Spectrofluorimetric Determination of Trace Amounts of Cr(VI) in the Presence of Cr(III) Abs: A simple, selective and sensitive fluorescence quenching method was developed to the determination Cr(VI). The method is based on the oxidation of I(-) to I(3)(-) by Cr(VI) in sulfuric acid solution followed by immediate formation of ion association compound between I(3)(-) and rhodamine 6G in Tween-80 micellar media at room temperature. The influence of several surfactants on rhodamine 6G fluorescence signal was studied; particular attention was paid in the aggregation behavior of rhodamine 6G-Tween-80 system. The experimental parameters (e.g., type of surfactant, reagent concentration) were Studied and the optimal conditions were established. The linear calibration graph was obtained in the range 2.0 - 100.0 ng mL(-1) Cr(VI). The detection limit of the method was 0.37 ng mL(-1). The relative standard deviation (R.S.D.) is less than 5% (n = 5). The efficiency of the method for the determination of Cr(VI) in the presence of Cr(III) in the sample was investigated. The method was applied successfully to the determination of Cr(VI) and total Cr in water, and liver tissue samples."
1578186,Low et al. 1997,Chromium (VI) sorption on quaternized rice hulls,BIOSIS COPYRIGHT: BIOL ABS. The sorption of Cr(VI) from synthetic solution and electroplating waste by quaternized rice hulls was investigated under laboratory conditions to assess its potential in removing Cr(VI). The results show that quaternized rice hulls provided higher sorption capacity and a more workable pH range as compared to the untreated rice hulls. From the Langmuir isotherm the maximum sorption capacity of Cr(VI) was 32.3 mg/g at pH 4.82 at 250 C. Column studies showed that Cr(VI) and Cu(II) from electroplating waste could be successfully removed or reduced using a combination of untreated and quaternized rice hulls. The effect of different anions on the sorption capacity of quarternized rice hulls was discussed.,Chromium (VI) sorption on quaternized rice hulls Abs: BIOSIS COPYRIGHT: BIOL ABS. The sorption of Cr(VI) from synthetic solution and electroplating waste by quaternized rice hulls was investigated under laboratory conditions to assess its potential in removing Cr(VI). The results show that quaternized rice hulls provided higher sorption capacity and a more workable pH range as compared to the untreated rice hulls. From the Langmuir isotherm the maximum sorption capacity of Cr(VI) was 32.3 mg/g at pH 4.82 at 250 C. Column studies showed that Cr(VI) and Cu(II) from electroplating waste could be successfully removed or reduced using a combination of untreated and quaternized rice hulls. The effect of different anions on the sorption capacity of quarternized rice hulls was discussed.
1578185,Lou et al. 2010,Selective Oxidation of Benzoins with Chromic Acid Supported on Aluminum Silicate Under Viscous Conditions,"Efficient oxidation of benzoins to corresponding benzils using chromic acid supported on aluminum silicate reagent under viscous conditions at room temperature is described, and all the reactions are completed within 3 hours in yields between 82-92%. The present procedure can overcome the problems existed in the common solvent-free reactions of the difficulty for the solid molecular collision to react. In addition, owing to the reaction using a very minimum amount of solvents, combustion, toxicity, and environmental pollution of the solvents are quite reduced.","Selective Oxidation of Benzoins with Chromic Acid Supported on Aluminum Silicate Under Viscous Conditions Abs: Efficient oxidation of benzoins to corresponding benzils using chromic acid supported on aluminum silicate reagent under viscous conditions at room temperature is described, and all the reactions are completed within 3 hours in yields between 82-92%. The present procedure can overcome the problems existed in the common solvent-free reactions of the difficulty for the solid molecular collision to react. In addition, owing to the reaction using a very minimum amount of solvents, combustion, toxicity, and environmental pollution of the solvents are quite reduced."
1578184,Lou et al. 2011,SELECTIVE OXIDATION OF BENZOINS WITH CHROMIC ACID SUPPORTED ON SILICA GEL UNDER VISCOUS CONDITIONS,"An efficient route for the oxidation of benzoins to corresponding benzils using chromic acid supported on silica gel reagent under viscous conditions at room temperature is described. All the reactions are completed within 4 h in yields between 86-91%. The present procedure can overcome the problems existed in the common solvent-free reactions of the difficulty for the solid molecular collision to react. In addition, due to the reaction using a very minimum amount of solvents, combustion, toxicity, and environmental pollution of the solvents are quite reduced.","SELECTIVE OXIDATION OF BENZOINS WITH CHROMIC ACID SUPPORTED ON SILICA GEL UNDER VISCOUS CONDITIONS Abs: An efficient route for the oxidation of benzoins to corresponding benzils using chromic acid supported on silica gel reagent under viscous conditions at room temperature is described. All the reactions are completed within 4 h in yields between 86-91%. The present procedure can overcome the problems existed in the common solvent-free reactions of the difficulty for the solid molecular collision to react. In addition, due to the reaction using a very minimum amount of solvents, combustion, toxicity, and environmental pollution of the solvents are quite reduced."
1578183,Lima et al. 2001,Application of novel photoacoustic measurement designs to Chromium (VI) determination in water,"With the increasing human awareness in environmental problems, the detection of pollutant elements in water has become of increasing importance. In order to achieve higher sensitivity and selectivity than those of the traditional spectroscopic methods, the use of photothermal (PT) techniques is advantageous. These techniques enclose a group of high sensitivity methods based in a photoinduced periodical change in the thermal state of a sample. Light energy absorbed and not lost by reemission leads to sample heating, which induces changes in temperature dependent sample parameters and/or variation in temperature dependent properties of the medium in which it is enclosed. The measurement of these changes is the basis of the PT methods. The Optothermal Window (OW) technique, actually a variant of conventional Photoacoustic (PA) Spectroscopy, is especially suitable for spectroscopic studies of strongly absorbing liquids. We report about its use for the determination of Chromium (VT) in water, a field currently of considerable interest due to Cr (VI) toxicity to live organisms, including humans. Their maximum allowed value in drinking water (0.96 mu mol/l) is well resolved in our experiments as well as the detection limits of Optical Spectrophotometry. The obtained results were compared with those obtained using a special designed, microphone based open PA cell, showing a good agreement.","Application of novel photoacoustic measurement designs to Chromium (VI) determination in water Abs: With the increasing human awareness in environmental problems, the detection of pollutant elements in water has become of increasing importance. In order to achieve higher sensitivity and selectivity than those of the traditional spectroscopic methods, the use of photothermal (PT) techniques is advantageous. These techniques enclose a group of high sensitivity methods based in a photoinduced periodical change in the thermal state of a sample. Light energy absorbed and not lost by reemission leads to sample heating, which induces changes in temperature dependent sample parameters and/or variation in temperature dependent properties of the medium in which it is enclosed. The measurement of these changes is the basis of the PT methods. The Optothermal Window (OW) technique, actually a variant of conventional Photoacoustic (PA) Spectroscopy, is especially suitable for spectroscopic studies of strongly absorbing liquids. We report about its use for the determination of Chromium (VT) in water, a field currently of considerable interest due to Cr (VI) toxicity to live organisms, including humans. Their maximum allowed value in drinking water (0.96 mu mol/l) is well resolved in our experiments as well as the detection limits of Optical Spectrophotometry. The obtained results were compared with those obtained using a special designed, microphone based open PA cell, showing a good agreement."
1578182,Lewis and  Yan 1995,CHROME DYEING USING ANIONIC TRIVALENT CHROMIUM COMPLEXES AS MORDANTS,"Chrome dyeings are normally produced by first applying an acid dye containing ligand groups and then afterchroming with hexavalent chromium derivatives such as dichromate salts. The latter can damage wool fibres and also are toxic components in dyehouse effluents, so afterchroming with mixtures of CT(HI) salts and organic acids has been studied. It has been shown that the anionic complexes that form from trivalent chromium and the organic acids are fibre substantive at pH 2-4 and have the correct stability profile for exchanging ligands to bind the chromium with ligand groups in the dye. Dyeings produced generally show colour yields and fastness properties similar to the normal Cr(vl) dyeing process; the exception are these chromophores which undergo oxidative change in the dichromate process.","CHROME DYEING USING ANIONIC TRIVALENT CHROMIUM COMPLEXES AS MORDANTS Abs: Chrome dyeings are normally produced by first applying an acid dye containing ligand groups and then afterchroming with hexavalent chromium derivatives such as dichromate salts. The latter can damage wool fibres and also are toxic components in dyehouse effluents, so afterchroming with mixtures of CT(HI) salts and organic acids has been studied. It has been shown that the anionic complexes that form from trivalent chromium and the organic acids are fibre substantive at pH 2-4 and have the correct stability profile for exchanging ligands to bind the chromium with ligand groups in the dye. Dyeings produced generally show colour yields and fastness properties similar to the normal Cr(vl) dyeing process; the exception are these chromophores which undergo oxidative change in the dichromate process."
1578180,Lee et al. 1999,The relationship between adsorption of Cr(VI) and soil properties,"The adsorption of hexavalent chromium from dilute aqueous solution onto fifteen Taiwan soils has been investigated using pH as the major variable. The soil samples were thoroughly characterized for their physical chemical properties and composition of organic matter and metal oxides. The adsorption of Cr(VI) followed the Langmuir relation and decreased with increasing pH between pH 2.5 and 9.5. At constant pH and metal concentration, soils with greater organic matter content adsorbed more Cr(VI). The experimental results were tested in a partition coefficient model to relate the adsorption of the Cr(VI) by the different soils with soil components: organic matter, iron oxide, aluminum oxide and manganese oxide. This model was not successful when applied to measurements at the natural soil pH because of the competition of hydroxyl ions with hexavalent chromium for available sites. However. partition coefficients obtained from experimental data at a fixed pH were highly correlated with those calculated for a partition coefficient between hexavalent chromium and organic matter alone. Normalization of the partition coefficients, K-d, for the organic matter content of the soils, K-om, greatly improved the correlation between the partition coefficient and pH (R-2 increased from 0.602 to 0.855). This suggests that the surficial adsorption sites are principally due to organic matter.","The relationship between adsorption of Cr(VI) and soil properties Abs: The adsorption of hexavalent chromium from dilute aqueous solution onto fifteen Taiwan soils has been investigated using pH as the major variable. The soil samples were thoroughly characterized for their physical chemical properties and composition of organic matter and metal oxides. The adsorption of Cr(VI) followed the Langmuir relation and decreased with increasing pH between pH 2.5 and 9.5. At constant pH and metal concentration, soils with greater organic matter content adsorbed more Cr(VI). The experimental results were tested in a partition coefficient model to relate the adsorption of the Cr(VI) by the different soils with soil components: organic matter, iron oxide, aluminum oxide and manganese oxide. This model was not successful when applied to measurements at the natural soil pH because of the competition of hydroxyl ions with hexavalent chromium for available sites. However. partition coefficients obtained from experimental data at a fixed pH were highly correlated with those calculated for a partition coefficient between hexavalent chromium and organic matter alone. Normalization of the partition coefficients, K-d, for the organic matter content of the soils, K-om, greatly improved the correlation between the partition coefficient and pH (R-2 increased from 0.602 to 0.855). This suggests that the surficial adsorption sites are principally due to organic matter."
1578179,Lakatos et al. 2002,Coals as sorbents for the removal and reduction of hexavalent chromium from aqueous waste streams,"The aim of this study is to demonstrate the potential of coals as a low-cost reactive barrier material for environmental protection applications, with the ability to prevent leaching of toxic Cr(VI) and other transition metals. Depending upon the type of ion and the surface functionalities, the uptake can involve ion sorption, ion exchange, chelation and redox mechanisms with the surface functionalities being considered as partners in electron transfer processes. The capacity for Cr(VI) uptake of low rank coals and oxidized bituminous coals has been found to lie within the range 0.2-0.6 mM g(-1). Air oxidation of bituminous coals can increase their Cr(VI) removal capacities. The effect of air oxidation of coals on uptake capacity was more pronounced for Cr(VI) than Cr(III), but less than for Hg(II) and the other ions (Ca2+, Ba2+, Zn2+, Cd-2) investigated. As previously found for Hg(II), redox mechanisms play an important role in Cr(VI) uptake, with sorption of the resultant Cr(III) being aided by the functionalities arising from oxidation of the coal surface. In acidic media, much of the resultant Cr(III) is exchanged back into solution by hydrogen ions, but some of the sorbed chromium is irreversibly bound to the coal. The reduction of Cr(VI) alone is often considered a satisfactory solution in view of Cr(111) being essentially non-toxic. (C) 2001 Elsevier Science Ltd. All rights reserved.","Coals as sorbents for the removal and reduction of hexavalent chromium from aqueous waste streams Abs: The aim of this study is to demonstrate the potential of coals as a low-cost reactive barrier material for environmental protection applications, with the ability to prevent leaching of toxic Cr(VI) and other transition metals. Depending upon the type of ion and the surface functionalities, the uptake can involve ion sorption, ion exchange, chelation and redox mechanisms with the surface functionalities being considered as partners in electron transfer processes. The capacity for Cr(VI) uptake of low rank coals and oxidized bituminous coals has been found to lie within the range 0.2-0.6 mM g(-1). Air oxidation of bituminous coals can increase their Cr(VI) removal capacities. The effect of air oxidation of coals on uptake capacity was more pronounced for Cr(VI) than Cr(III), but less than for Hg(II) and the other ions (Ca2+, Ba2+, Zn2+, Cd-2) investigated. As previously found for Hg(II), redox mechanisms play an important role in Cr(VI) uptake, with sorption of the resultant Cr(III) being aided by the functionalities arising from oxidation of the coal surface. In acidic media, much of the resultant Cr(III) is exchanged back into solution by hydrogen ions, but some of the sorbed chromium is irreversibly bound to the coal. The reduction of Cr(VI) alone is often considered a satisfactory solution in view of Cr(111) being essentially non-toxic. (C) 2001 Elsevier Science Ltd. All rights reserved."
1578178,Labouche and  Traisnel 1994,A CONTRIBUTION TO THE STUDY OF NEW NONTOXIC INHIBITOR BEHAVIOR,"The battle against the electrochemical corrosion of steel generally involves the use of inhibitive pigments in paints. Zinc chromate is well known for its efficiency and was widely used in anti-corrosive primers in the past, but is now abandoned because of its toxicity. Electrochemical analysis techniques, including AC impedance measurements, were used in order to study and compare the performances of non-toxic inhibitive pigments in water and their behaviour in two primers. The results obtained by studying the aqueous solutions of inhibitors correlated well with outdoor exposure. The study of the faradic resistance of painted steel demonstrated the risk in using the NFX 41002 salt spray test commonly used as a selection test. All the techniques used allowed us to demonstrate that it is necessary to associate an adhesion promoter in conjunction with the new inhibitive pigment in order to prevent the sensitivity of paint films to water penetration. In particular, AC impedance measurements showed a concomitant increase of the ionic and faradic resistance of a zinc borate-containing epoxy ester based primer when this inhibitor was used in conjunction with dioctyl pyrophosphato-oxyacetate of titanium.","A CONTRIBUTION TO THE STUDY OF NEW NONTOXIC INHIBITOR BEHAVIOR Abs: The battle against the electrochemical corrosion of steel generally involves the use of inhibitive pigments in paints. Zinc chromate is well known for its efficiency and was widely used in anti-corrosive primers in the past, but is now abandoned because of its toxicity. Electrochemical analysis techniques, including AC impedance measurements, were used in order to study and compare the performances of non-toxic inhibitive pigments in water and their behaviour in two primers. The results obtained by studying the aqueous solutions of inhibitors correlated well with outdoor exposure. The study of the faradic resistance of painted steel demonstrated the risk in using the NFX 41002 salt spray test commonly used as a selection test. All the techniques used allowed us to demonstrate that it is necessary to associate an adhesion promoter in conjunction with the new inhibitive pigment in order to prevent the sensitivity of paint films to water penetration. In particular, AC impedance measurements showed a concomitant increase of the ionic and faradic resistance of a zinc borate-containing epoxy ester based primer when this inhibitor was used in conjunction with dioctyl pyrophosphato-oxyacetate of titanium."
1578177,Ksheminska et al. 2008,Yeast Tolerance to Chromium Depends on Extracellular Chromate Reduction and Cr(III) Chelation,"The sensitivity of the yeast Pichia guilliermondii ATCC 201911 (L2) to Cr(VI) and Cr(III) has been investigated. This yeast was demonstrated to have much higher resistance to Cr(III), compared to Cr(VI). At chromate level of 2.0 mM, an expanded lag phase in growth was observed, followed by the active phase of cell proliferation. During the growth arrest, a residual external chromate concentration decreased gradually to the nontoxic level, and the duration of this period was directly dependent on the initial Cr(VI) concentration in the medium, i.e. the higher the Cr(VI) level, the longer the growth delay. Thus, the tolerance of R guilliermondii to chromate depends on its capacity for extracellular reduction of Cr(VI). As a product of chromate reduction, Cr(III) forms complexes with the components of culture liquid, which are not effectively adsorbed by the cells and do not repress the growth of R guilliermondii. When urea is used as a nitrogen source, not only chromate reduction, but also Cr(III) chelation were shown to decrease, compared to the medium supplemented with ammonium sulphate. The experimental data confirm this concept of extracellular reduction of Cr(VI) as an important mechanism, which provides the resistance of yeast cells to chromate.","Yeast Tolerance to Chromium Depends on Extracellular Chromate Reduction and Cr(III) Chelation Abs: The sensitivity of the yeast Pichia guilliermondii ATCC 201911 (L2) to Cr(VI) and Cr(III) has been investigated. This yeast was demonstrated to have much higher resistance to Cr(III), compared to Cr(VI). At chromate level of 2.0 mM, an expanded lag phase in growth was observed, followed by the active phase of cell proliferation. During the growth arrest, a residual external chromate concentration decreased gradually to the nontoxic level, and the duration of this period was directly dependent on the initial Cr(VI) concentration in the medium, i.e. the higher the Cr(VI) level, the longer the growth delay. Thus, the tolerance of R guilliermondii to chromate depends on its capacity for extracellular reduction of Cr(VI). As a product of chromate reduction, Cr(III) forms complexes with the components of culture liquid, which are not effectively adsorbed by the cells and do not repress the growth of R guilliermondii. When urea is used as a nitrogen source, not only chromate reduction, but also Cr(III) chelation were shown to decrease, compared to the medium supplemented with ammonium sulphate. The experimental data confirm this concept of extracellular reduction of Cr(VI) as an important mechanism, which provides the resistance of yeast cells to chromate."
1578173,Klemm 1994,HEXAVALENT CHROMIUM IN PORTLAND-CEMENT,"Due to increasing environmental and health-related concerns, the amount of hexavalent chromium found in portland cement is coming under increasing scrutiny. Hexavalent chromium has been classified as a carcinogen, and its release into the air or groundwater is regulated and controlled under many Federal and State regulations. In addition to carcinogenic risks, soluble chromium has long been linked to chromate-sensitive contact dermatitis of workers exposed to wet cement or concrete. As a consequence, Scandinavian countries have limited the amount of hexavalent chromium allowed in portland cement. This is generally accomplished by intergrinding clinker and gypsum with the chemical reducing agent, ferrous sulfate, which maintains hexavalent chromium below 2 ppm. Developments in this area are reviewed. Studies at a California cement plant showed that more than half of the hexavalent chromium in the cement was contributed by the grinding media in the finish mill. Attempts to reduce the chromium to its benign trivalent form with ferrous sulfate failed in full-scale trial grinds, due to oxidation of the ferrous iron. This indicates that further research is needed to find better methods for introducing ferrous sulfate into the cement or to develop more stable reducing agents.","HEXAVALENT CHROMIUM IN PORTLAND-CEMENT Abs: Due to increasing environmental and health-related concerns, the amount of hexavalent chromium found in portland cement is coming under increasing scrutiny. Hexavalent chromium has been classified as a carcinogen, and its release into the air or groundwater is regulated and controlled under many Federal and State regulations. In addition to carcinogenic risks, soluble chromium has long been linked to chromate-sensitive contact dermatitis of workers exposed to wet cement or concrete. As a consequence, Scandinavian countries have limited the amount of hexavalent chromium allowed in portland cement. This is generally accomplished by intergrinding clinker and gypsum with the chemical reducing agent, ferrous sulfate, which maintains hexavalent chromium below 2 ppm. Developments in this area are reviewed. Studies at a California cement plant showed that more than half of the hexavalent chromium in the cement was contributed by the grinding media in the finish mill. Attempts to reduce the chromium to its benign trivalent form with ferrous sulfate failed in full-scale trial grinds, due to oxidation of the ferrous iron. This indicates that further research is needed to find better methods for introducing ferrous sulfate into the cement or to develop more stable reducing agents."
1578167,Kamas 1995,AMMONIA COMPLEXATION IN THE ANALYSIS OF HEXAVALENT CHROMIUM IN FLY-ASH,Municipal waste incinerator fly ash was analyzed employing ion chromatography with post column derivatization. The aim of this work was to investigate digestion media to determine appropriate sample analysis conditions for Cr(VI) analysis of fly ash. The effect of digestion media and conditions were evaluated with respect to Cr(VI) spike recovery and Cr(III) oxidation. Evidence is presented demonstrating that oxidation of Cr(III) in alkaline media is reduced by 65 to 95% upon the addition of ammonia. This is attributed to complexation of ammonia and Cr(III). It is also demonstrated that ammonia enhances spike recovery of Cr(VI) fortified fly ash by 10 to 20%. The mechanism for the improvement in Cr(VI) analysis by ammonia is a result of interfacial and associative interactions. Data is presented that specifically establishes an associative interaction between ammonia and Cr(VI). Recommendations are made for improvement of existing Cr(VI) analysis procedures and collection systems.,AMMONIA COMPLEXATION IN THE ANALYSIS OF HEXAVALENT CHROMIUM IN FLY-ASH Abs: Municipal waste incinerator fly ash was analyzed employing ion chromatography with post column derivatization. The aim of this work was to investigate digestion media to determine appropriate sample analysis conditions for Cr(VI) analysis of fly ash. The effect of digestion media and conditions were evaluated with respect to Cr(VI) spike recovery and Cr(III) oxidation. Evidence is presented demonstrating that oxidation of Cr(III) in alkaline media is reduced by 65 to 95% upon the addition of ammonia. This is attributed to complexation of ammonia and Cr(III). It is also demonstrated that ammonia enhances spike recovery of Cr(VI) fortified fly ash by 10 to 20%. The mechanism for the improvement in Cr(VI) analysis by ammonia is a result of interfacial and associative interactions. Data is presented that specifically establishes an associative interaction between ammonia and Cr(VI). Recommendations are made for improvement of existing Cr(VI) analysis procedures and collection systems.
1578165,Ipatova and  Prokhotskaia 2002,Algal resistance to heavy metals,"There are many experimental data about algal adaptation to heavy metals. The result of adaptation is increasing of resistance to toxicants during the time. In the case of chronic intoxication this process can develop by selection of already existent forms in genetically heterogeneous population (genetic adaptation) or by forming of resistant cells of algae within population (biochemical or phenotypic adaptation). It is important to know the limits of algal population resistance to long-term high intensive toxic effects for hydrosphere monitoring. In present work we estimated resistance of laboratory population of green chlorococcal, alga Scenedesmus quadricauda (Turp.) Breb. to potassium dichromate (K(2)Cr(2)O(7)) as a model toxicant. After the pre-adaptation to relatively low concentrations of toxicant the algae were re-moculated twice in medium with 10.0 mg/l K(2)Cr(2)O(7) (excluding control culture). It was revealed that the number of cells depended on initial K(2)Cr(2)O(7) concentration: the higher the toxicant concentration was, the less cell number was. So, in a 30 days maximum cell number was in pre-adapted with 0.1 mg/l K(2)Cr(2)O(7) culture. In another 30 days the cell number was the same in all samples (5-6% of initial cell number). During the experiment photosynthetic efficiency decreased accordingly to toxicant concentration: the higher concentration was, the lower photosynthetic activity was. Living cells were found out in cultures after three-time intoxication. They had size spectra and functional characteristics the same than a control ones. The resistant cells are suggested to relate to their constant presence in population or are the result of selection. It is need of special research for clarification of this phenomenon. The laboratory microalgal cultures are optimal models for investigation of toxic action on population and cell levels [1, 2]. They have short-term life cycle and, therefore, can produce many daughter cells during short period of time. The using of algal cultures in toxicological experiments gives an opportunity; first, to research effects of toxicants on functional and morphological characteristics of plant cell and,, second, to estimate their action on microalgal model population. The intensity of toxic action should be evaluated by the cell number changing during the cultivation. Variability of cell number is reported to reflect the algal population state adequately [3, 4]. There is vast experimental information about chemical waste effects on plants, including algal adaptation to heavy metal action [5-7]. The result of adaptation is increasing of resistance to toxicants during the time. In the case of chronic intoxication this process can develop by selection of already existent forms in genetically heterogeneous population (genetic adaptation) or by forming of resistant cells of algae within population (biochemical or phenotypic adaptation). The limits of algal cells resistance to long-term high intensive toxic effects determine survival of population as whole. Thus, research of algal adaptation to adverse conditions is of primary importance for hydrosphere monitoring. We were shown earlier that the algal culture previously growing in the presence of low concentrations of toxicants attained resistance to higher toxic concentrations [10]. The aim of present investigation was to estimate resistance of laboratory population of green chlorococcal alga Scenedesmus quadricauda (Turp.) Breb. to potassium dichromate (K(2)Cr(2)O(7)) as a model toxicant.","Algal resistance to heavy metals Abs: There are many experimental data about algal adaptation to heavy metals. The result of adaptation is increasing of resistance to toxicants during the time. In the case of chronic intoxication this process can develop by selection of already existent forms in genetically heterogeneous population (genetic adaptation) or by forming of resistant cells of algae within population (biochemical or phenotypic adaptation). It is important to know the limits of algal population resistance to long-term high intensive toxic effects for hydrosphere monitoring. In present work we estimated resistance of laboratory population of green chlorococcal, alga Scenedesmus quadricauda (Turp.) Breb. to potassium dichromate (K(2)Cr(2)O(7)) as a model toxicant. After the pre-adaptation to relatively low concentrations of toxicant the algae were re-moculated twice in medium with 10.0 mg/l K(2)Cr(2)O(7) (excluding control culture). It was revealed that the number of cells depended on initial K(2)Cr(2)O(7) concentration: the higher the toxicant concentration was, the less cell number was. So, in a 30 days maximum cell number was in pre-adapted with 0.1 mg/l K(2)Cr(2)O(7) culture. In another 30 days the cell number was the same in all samples (5-6% of initial cell number). During the experiment photosynthetic efficiency decreased accordingly to toxicant concentration: the higher concentration was, the lower photosynthetic activity was. Living cells were found out in cultures after three-time intoxication. They had size spectra and functional characteristics the same than a control ones. The resistant cells are suggested to relate to their constant presence in population or are the result of selection. It is need of special research for clarification of this phenomenon. The laboratory microalgal cultures are optimal models for investigation of toxic action on population and cell levels [1, 2]. They have short-term life cycle and, therefore, can produce many daughter cells during short period of time. The using of algal cultures in toxicological experiments gives an opportunity; first, to research effects of toxicants on functional and morphological characteristics of plant cell and,, second, to estimate their action on microalgal model population. The intensity of toxic action should be evaluated by the cell number changing during the cultivation. Variability of cell number is reported to reflect the algal population state adequately [3, 4]. There is vast experimental information about chemical waste effects on plants, including algal adaptation to heavy metal action [5-7]. The result of adaptation is increasing of resistance to toxicants during the time. In the case of chronic intoxication this process can develop by selection of already existent forms in genetically heterogeneous population (genetic adaptation) or by forming of resistant cells of algae within population (biochemical or phenotypic adaptation). The limits of algal cells resistance to long-term high intensive toxic effects determine survival of population as whole. Thus, research of algal adaptation to adverse conditions is of primary importance for hydrosphere monitoring. We were shown earlier that the algal culture previously growing in the presence of low concentrations of toxicants attained resistance to higher toxic concentrations [10]. The aim of present investigation was to estimate resistance of laboratory population of green chlorococcal alga Scenedesmus quadricauda (Turp.) Breb. to potassium dichromate (K(2)Cr(2)O(7)) as a model toxicant."
1578164,Iezzoni et al. 1993,RECENT ADVANCES IN AUTOMATED IMMUNOCYTOCHEMISTRY,"We describe an automated immunocytochemical assay that is performed with the Code-On Immuno/DNA Slide Stainer, in 64 min from dewaxing to counterstaining, on B5 or formalin fixed, paraffin embedded tissue sections. The instrument uses capillary action to apply sequentially, incubate, and drain all the reagents in the assay. Up to 60 slides can be processed in a single run. A new automated immunostaining program, AECSTAIN, which uses 3-amino, 9-ethylcarbazole (AEC) as the chromogen, is described in detail. Several advances in automated immunostaining that contribute to the efficiency of the program are reported, including commercially available positively charged glass slides for improved adherence of tissue sections, blot drying for rapid tissue immobilization, a mixed limolene-xylene clearing solution for efficient dewaxing, an acid-alcohol-iodine solution for rapid dezenkerization, surface cleaning of the glass slides and tissue sections with chromic acid, stabilization of the pepsin solution used for predigestion, rapid enhancement of the chromogen's colorimetric signal, and detergent stabilization of the hematoxylin counterstain. Batteries of immunostains, using 32 different primary monoclonal and polyclonal antibodies against intermediate filaments, hematolymphoid markers, infectious agents, and tumor markers, are produced simultaneously and rapidly by this single automated method.","RECENT ADVANCES IN AUTOMATED IMMUNOCYTOCHEMISTRY Abs: We describe an automated immunocytochemical assay that is performed with the Code-On Immuno/DNA Slide Stainer, in 64 min from dewaxing to counterstaining, on B5 or formalin fixed, paraffin embedded tissue sections. The instrument uses capillary action to apply sequentially, incubate, and drain all the reagents in the assay. Up to 60 slides can be processed in a single run. A new automated immunostaining program, AECSTAIN, which uses 3-amino, 9-ethylcarbazole (AEC) as the chromogen, is described in detail. Several advances in automated immunostaining that contribute to the efficiency of the program are reported, including commercially available positively charged glass slides for improved adherence of tissue sections, blot drying for rapid tissue immobilization, a mixed limolene-xylene clearing solution for efficient dewaxing, an acid-alcohol-iodine solution for rapid dezenkerization, surface cleaning of the glass slides and tissue sections with chromic acid, stabilization of the pepsin solution used for predigestion, rapid enhancement of the chromogen's colorimetric signal, and detergent stabilization of the hematoxylin counterstain. Batteries of immunostains, using 32 different primary monoclonal and polyclonal antibodies against intermediate filaments, hematolymphoid markers, infectious agents, and tumor markers, are produced simultaneously and rapidly by this single automated method."
1578163,Hachimi et al. 1993,EXTENSIVE STUDY OF OXIDATION-STATES OF CHROMIUM IN PARTICLES BY LAMMA AND RAMAN MICROPROBES - APPLICATION TO INDUSTRIAL-HYGIENE,"The iron and steel industry is a major source of dust emissions which contain metal oxides. In this chemical state, metals are sometimes toxic and their carcinogenic effects have been intensively studied and demonstrated. Here we used the method developed in our laboratory for the determination of chromium valency in particles less than 10 mum in size emitted as dust by the steel industry. The method has been improved by a precise sampling using granulometric discrimination (Impactor Andersen) and selection of dust emission sites. The systematic LAMMA analysis of the particles showed that the oxidation of the chromium depends on the particle size. We determined the site emitting the particles containing the more hexavalent chromium. The situation has been simulated by using a portable cascade impactor carried by a person working on-site. Crossed and detailed studies using three complementary in situ analysis techniques of high-sized particles sampled on the worker showed that chromium present in these dusts consisted mainly of calcium chromates.","EXTENSIVE STUDY OF OXIDATION-STATES OF CHROMIUM IN PARTICLES BY LAMMA AND RAMAN MICROPROBES - APPLICATION TO INDUSTRIAL-HYGIENE Abs: The iron and steel industry is a major source of dust emissions which contain metal oxides. In this chemical state, metals are sometimes toxic and their carcinogenic effects have been intensively studied and demonstrated. Here we used the method developed in our laboratory for the determination of chromium valency in particles less than 10 mum in size emitted as dust by the steel industry. The method has been improved by a precise sampling using granulometric discrimination (Impactor Andersen) and selection of dust emission sites. The systematic LAMMA analysis of the particles showed that the oxidation of the chromium depends on the particle size. We determined the site emitting the particles containing the more hexavalent chromium. The situation has been simulated by using a portable cascade impactor carried by a person working on-site. Crossed and detailed studies using three complementary in situ analysis techniques of high-sized particles sampled on the worker showed that chromium present in these dusts consisted mainly of calcium chromates."
1578162,Gupta et al. 1993,OXIDATIVE BEHAVIOR OF SOME AMINOSUGARS TOWARDS CHROMIC-ACID IN PERCHLORIC-ACID MEDIUM IN THE ABSENCE AND PRESENCE OF MICELLAR ENVIRONMENT,The oxidative behaviour of some aminosugars towards chromium(VI) in perchloric acid medium has been investigated. Chromium(VI) reacts with glucosamine and galactosamine by a similar mechanistic path through the intermediate formation of 1:1 complex between the reactants whereas the kinetic evidence for such 1:1 complex formation between protonated mannosamine and the reactive oxidant is insignificant. The influence of added micelle on the rate has also been studied.,OXIDATIVE BEHAVIOR OF SOME AMINOSUGARS TOWARDS CHROMIC-ACID IN PERCHLORIC-ACID MEDIUM IN THE ABSENCE AND PRESENCE OF MICELLAR ENVIRONMENT Abs: The oxidative behaviour of some aminosugars towards chromium(VI) in perchloric acid medium has been investigated. Chromium(VI) reacts with glucosamine and galactosamine by a similar mechanistic path through the intermediate formation of 1:1 complex between the reactants whereas the kinetic evidence for such 1:1 complex formation between protonated mannosamine and the reactive oxidant is insignificant. The influence of added micelle on the rate has also been studied.
1578152,Greene et al. 1992,"DETERMINATION OF HEXAVALENT CHROMIUM IN SOME CONTAMINATED SOILS FROM HUDSON-COUNTY, NEW-JERSEY","The efficiency of extracting hexavalent chromium from a silica matrix with a 3 % sodium carbonate-1 % sodium hydroxide solution was demonstrated using an ""in-house"" reference material, and this extraction procedure was successfully applied to the determination of hexavalent chromium in some contaminated soils from Hudson County, New Jersey.","DETERMINATION OF HEXAVALENT CHROMIUM IN SOME CONTAMINATED SOILS FROM HUDSON-COUNTY, NEW-JERSEY Abs: The efficiency of extracting hexavalent chromium from a silica matrix with a 3 % sodium carbonate-1 % sodium hydroxide solution was demonstrated using an ""in-house"" reference material, and this extraction procedure was successfully applied to the determination of hexavalent chromium in some contaminated soils from Hudson County, New Jersey."
1578151,Godgul and  Sahu 1995,CHROMIUM CONTAMINATION FROM CHROMITE MINE,"Among the dominant species of chromium, the trivalent form widely occurs in nature in chromite ores or in silicate minerals and is extremely immobile. The higher oxidation state Cr(VI), is, however, rarely found in nature, is more mobile, and several times more toxic than Cr(III). Cr(VI) occurs in chromates and dichromates manufactured from chromite ores. The hexavalent state is stable in an oxidizing alkaline environment, whereas the trivalent state is stable in a reducing acidic environment. Serpentinization and Mg release during deuteric alteration of ultramafic rocks create alkaline pore water and lateritization is an intensive oxidation process. Chromite ore bodies in oxidized serpentinite therefore may generate hexavalent chromium from the inert chromites and cause hazardous chromium pollution of the water. With this end in view, a combined field and laboratory study has been made on chromite-bearing oxidized serpentinite rocks of Sukinda in Orissa, India. Laboratory leaching studies on mine overburden samples, chemical analyses of streamwater, and hydrolysate incrustation on detrital grains taken from stream beds have indicated the possibility of chromium mobilization from the chromite ores into the waterbodies.","CHROMIUM CONTAMINATION FROM CHROMITE MINE Abs: Among the dominant species of chromium, the trivalent form widely occurs in nature in chromite ores or in silicate minerals and is extremely immobile. The higher oxidation state Cr(VI), is, however, rarely found in nature, is more mobile, and several times more toxic than Cr(III). Cr(VI) occurs in chromates and dichromates manufactured from chromite ores. The hexavalent state is stable in an oxidizing alkaline environment, whereas the trivalent state is stable in a reducing acidic environment. Serpentinization and Mg release during deuteric alteration of ultramafic rocks create alkaline pore water and lateritization is an intensive oxidation process. Chromite ore bodies in oxidized serpentinite therefore may generate hexavalent chromium from the inert chromites and cause hazardous chromium pollution of the water. With this end in view, a combined field and laboratory study has been made on chromite-bearing oxidized serpentinite rocks of Sukinda in Orissa, India. Laboratory leaching studies on mine overburden samples, chemical analyses of streamwater, and hydrolysate incrustation on detrital grains taken from stream beds have indicated the possibility of chromium mobilization from the chromite ores into the waterbodies."
1578150,Fu et al. 2013,Effects of Permeable Reactive Composite Electrodes on Hexavalent Chromium in the Electrokinetic Remediation of Contaminated Soil,"Electrokinetic transport processes have been shown to have potential for effective removal of heavy metals from soils. However, pH changes near the anode and cathode limit their widespread application in remediation of contaminated soils. Permeable reactive composite electrodes (PRCEs) were constructed by attaching reactive materials such as Fe(0) and zeolite to electrodes, and effects of composite electrodes on pH control, chromium (Cr) removal efficiency, and adjustment of speciation of Cr were studied in the electrokinetic remediation of Cr(VI)-spiked soil. Composite electrodes consisting of permeable reactive materials gave better pH control and Cr removal efficiency compared to application of traditional electrodes, and a reactive layer of Fe(0) and zeolite in the anode exhibited the best performance compared to zeolite or Fe(0) alone. After 5 d of electrokinetic remediation with a DC voltage of 2.0 V/cm, the Fe(0) + zeolite reactive layer buffered pH fluctuation, maintained soil pH in the range of 5.5-8.5, and increased Cr(VI) remediation efficiency up to 97% in each section of soil. Additionally, it resulted in lower Cr(III) residues, enhancement of the amount of Cr retention up to 8 x and 1.8 x, respectively, and transformation of 98% of the Cr(VI) to lower toxicity Cr(III). After remediation, heavy metal ions were removed from the remediation system simply by unplugging the composite electrodes, which theoretically needed no further treatment-a major advantage over traditional electrokinetic remediation methods. This study provides a theoretical basis for exploitation of PRCEs, which is a practical option for future applications.","Effects of Permeable Reactive Composite Electrodes on Hexavalent Chromium in the Electrokinetic Remediation of Contaminated Soil Abs: Electrokinetic transport processes have been shown to have potential for effective removal of heavy metals from soils. However, pH changes near the anode and cathode limit their widespread application in remediation of contaminated soils. Permeable reactive composite electrodes (PRCEs) were constructed by attaching reactive materials such as Fe(0) and zeolite to electrodes, and effects of composite electrodes on pH control, chromium (Cr) removal efficiency, and adjustment of speciation of Cr were studied in the electrokinetic remediation of Cr(VI)-spiked soil. Composite electrodes consisting of permeable reactive materials gave better pH control and Cr removal efficiency compared to application of traditional electrodes, and a reactive layer of Fe(0) and zeolite in the anode exhibited the best performance compared to zeolite or Fe(0) alone. After 5 d of electrokinetic remediation with a DC voltage of 2.0 V/cm, the Fe(0) + zeolite reactive layer buffered pH fluctuation, maintained soil pH in the range of 5.5-8.5, and increased Cr(VI) remediation efficiency up to 97% in each section of soil. Additionally, it resulted in lower Cr(III) residues, enhancement of the amount of Cr retention up to 8 x and 1.8 x, respectively, and transformation of 98% of the Cr(VI) to lower toxicity Cr(III). After remediation, heavy metal ions were removed from the remediation system simply by unplugging the composite electrodes, which theoretically needed no further treatment-a major advantage over traditional electrokinetic remediation methods. This study provides a theoretical basis for exploitation of PRCEs, which is a practical option for future applications."
1578149,Fang et al. 2012,Electrochemical Reduction of Hexavalent Chromium on Two-step Electrosynthesized One-dimensional Polyaniline Nanowire,"In this work, polyaniline (PANI) film was synthesized by the two-step electrochemical polymerization method from sulfonic acid solution on the spectrographic pure graphite (SPG) surface. Scanning electron microscope (SEM) characterization shows that the resulting PANI film had porous morphology and loosely textured structure, which is composed of uniform 1D nanowires with an average diameter of about 100-200 nm. The electroreduction of Cr(VI) to the much less toxic trivalent state (Cr(III)) was then studied on the PANI/SPG electrode. The effects of various parameters such as cathode potential, solution pH, PANI film thickness and electrolyte temperature on the Cr(VI) removal rate were investigated in detail. It was found that the negative cathod potential, low solution pH and appropriate PANI film thickness are benefit for the removal of Cr(VI). While the electrolyte temperature had no evident effect on the Cr(VI) electroreduction reaction. The electrochemical stability of the PANI film after use in Cr(VI) reduction process was also investigated using cyclic voltammetry and Fourier transfer infrared spectroscopy technologies.","Electrochemical Reduction of Hexavalent Chromium on Two-step Electrosynthesized One-dimensional Polyaniline Nanowire Abs: In this work, polyaniline (PANI) film was synthesized by the two-step electrochemical polymerization method from sulfonic acid solution on the spectrographic pure graphite (SPG) surface. Scanning electron microscope (SEM) characterization shows that the resulting PANI film had porous morphology and loosely textured structure, which is composed of uniform 1D nanowires with an average diameter of about 100-200 nm. The electroreduction of Cr(VI) to the much less toxic trivalent state (Cr(III)) was then studied on the PANI/SPG electrode. The effects of various parameters such as cathode potential, solution pH, PANI film thickness and electrolyte temperature on the Cr(VI) removal rate were investigated in detail. It was found that the negative cathod potential, low solution pH and appropriate PANI film thickness are benefit for the removal of Cr(VI). While the electrolyte temperature had no evident effect on the Cr(VI) electroreduction reaction. The electrochemical stability of the PANI film after use in Cr(VI) reduction process was also investigated using cyclic voltammetry and Fourier transfer infrared spectroscopy technologies."
1578143,Alpoim et al. 1998,The protective role of NADH on chromium (VI) induced human erythrocytes cytotoxicity and human erythrocyte ghosts peroxidation,,The protective role of NADH on chromium (VI) induced human erythrocytes cytotoxicity and human erythrocyte ghosts peroxidation Abs: 
1578141,Kalirajan et al. 2010,Microwave Assisted Synthesis and Biological Evaluation of Pyrazole Derivatives of Benzimidazoles,"A series of pyrazole derivatives of benzimidazole were synthesized. Condensation of substituted o-phenylene diamine with lactic acid under microwave irradiation and further oxidation of the product with potassium dichromate gave intermediate 2-acetyl benzimidazole which was then reacted with aromatic aldehydes and finally the product was cyclized with hydrazine to form pyrazole derivatives of benzimidazoles. Compounds IVa, b, c, d, e have shown significant anti bacterial and compounds IV b, g have shown significant anti cancer activity when compared with standard drugs.","Microwave Assisted Synthesis and Biological Evaluation of Pyrazole Derivatives of Benzimidazoles Abs: A series of pyrazole derivatives of benzimidazole were synthesized. Condensation of substituted o-phenylene diamine with lactic acid under microwave irradiation and further oxidation of the product with potassium dichromate gave intermediate 2-acetyl benzimidazole which was then reacted with aromatic aldehydes and finally the product was cyclized with hydrazine to form pyrazole derivatives of benzimidazoles. Compounds IVa, b, c, d, e have shown significant anti bacterial and compounds IV b, g have shown significant anti cancer activity when compared with standard drugs."
1578140,Katre et al. 2011,INFLUENCE OF CETYLTRIMETHYLAMMONIUM BROMIDE/SODIUM DODECYLSULPHATE MICELLES ON THE OXIDATION OF D-FRUCTOSE BY N-BROMOPHTHALIMIDE IN THE PRESENCE OF SULPHURIC ACID. A KINETIC STUDY,"The kinetics and mechanism of the micellar-catalysed oxidation of D-fructose by N-bromophthalimide (NBP) in sulphuric acid (H(2)SO(4)) media has been investigated at 40 degrees C. The reaction exhibits fractional order, first order and negative fractional order kinetics with respect to [fructose], [NBP] and [H(2)SO(4)], respectively. In the presence of additives, the critical micellar concentration (CMC) values of surfactants are lower than those given in literature. Cationic micelle of cetyltrimethylammonium bromide (CTAB) catalyses the reaction, i.e. with a progressive increase in [CTAB], the reaction rate increased and at higher concentration reaction rate decreased. The observed micellar effects are explained by the applicability of the Berezin model considering a distribution pattern of the reactants between the micellar and aqueous phases. Anionic micelles of sodium dodecylsulphate (SDS) slightly inhibit the reaction. Variation of [phthalimide] showed that the rate of reaction decreased with increasing [phthalimide]. It was observed that on increasing [mercuric acetate] there was no change in reaction velocity. The effects of various inorganic salts were also studied in micellar media. The effect of [surfactants] on the activation parameters was explored to rationalise the micellar effect. A detailed mechanism with the associated reaction kinetics is presented and discussed.","INFLUENCE OF CETYLTRIMETHYLAMMONIUM BROMIDE/SODIUM DODECYLSULPHATE MICELLES ON THE OXIDATION OF D-FRUCTOSE BY N-BROMOPHTHALIMIDE IN THE PRESENCE OF SULPHURIC ACID. A KINETIC STUDY Abs: The kinetics and mechanism of the micellar-catalysed oxidation of D-fructose by N-bromophthalimide (NBP) in sulphuric acid (H(2)SO(4)) media has been investigated at 40 degrees C. The reaction exhibits fractional order, first order and negative fractional order kinetics with respect to [fructose], [NBP] and [H(2)SO(4)], respectively. In the presence of additives, the critical micellar concentration (CMC) values of surfactants are lower than those given in literature. Cationic micelle of cetyltrimethylammonium bromide (CTAB) catalyses the reaction, i.e. with a progressive increase in [CTAB], the reaction rate increased and at higher concentration reaction rate decreased. The observed micellar effects are explained by the applicability of the Berezin model considering a distribution pattern of the reactants between the micellar and aqueous phases. Anionic micelles of sodium dodecylsulphate (SDS) slightly inhibit the reaction. Variation of [phthalimide] showed that the rate of reaction decreased with increasing [phthalimide]. It was observed that on increasing [mercuric acetate] there was no change in reaction velocity. The effects of various inorganic salts were also studied in micellar media. The effect of [surfactants] on the activation parameters was explored to rationalise the micellar effect. A detailed mechanism with the associated reaction kinetics is presented and discussed."
1578139,Kazmi and  Rahman 1997,Kinetics and mechanism of conversion of carcinogen hexavalent Cr(VI) to Cr(III) by reduction with ascorbate,To asses the therapeutic efficacy of ascorbic acid in preventing toxic and mutagenic effects of Cr(VI) to Cr(III) the Kinetics and mechanism of reduction of hexavalent chromium by ascorbate has been studied. The reduction was done under pseudo first order condition by taking an excess of ascorbate over hexavalent chromium species. The rise of absorbance of Cr(III) was monitored at 578 nm. The observed rate constants then determined showed a dependence on both ascorbate concentration and pH as well. The bearing of these observations on the mechanism of reduction of hexavalent chromium is discussed in order to explain this.,Kinetics and mechanism of conversion of carcinogen hexavalent Cr(VI) to Cr(III) by reduction with ascorbate Abs: To asses the therapeutic efficacy of ascorbic acid in preventing toxic and mutagenic effects of Cr(VI) to Cr(III) the Kinetics and mechanism of reduction of hexavalent chromium by ascorbate has been studied. The reduction was done under pseudo first order condition by taking an excess of ascorbate over hexavalent chromium species. The rise of absorbance of Cr(III) was monitored at 578 nm. The observed rate constants then determined showed a dependence on both ascorbate concentration and pH as well. The bearing of these observations on the mechanism of reduction of hexavalent chromium is discussed in order to explain this.
1578138,Khare et al. 1997,Responses of Pseudomonas aeruginosa to chromium stress,"Chromium toxicity in a strain of Pseudomonas aeruginosa, isolated from tannery sediment, was relieved by the addition of carbon sources such as glucose, fructose and yeast extract (a source of amino acids and vitamins). Sodium chloride also relieved chromium toxicity experienced by Pseudomonas aeruginosa. Chromate-stressed cells produced siderophores under iron sufficiency. Chromate shock resulted in transient induction/enhancement of six proteins. Cultures grown with chromate stress, however, did not show any of the transiently induced proteins but revealed notable inhibition of one protein. (C) Elsevier, Paris.","Responses of Pseudomonas aeruginosa to chromium stress Abs: Chromium toxicity in a strain of Pseudomonas aeruginosa, isolated from tannery sediment, was relieved by the addition of carbon sources such as glucose, fructose and yeast extract (a source of amino acids and vitamins). Sodium chloride also relieved chromium toxicity experienced by Pseudomonas aeruginosa. Chromate-stressed cells produced siderophores under iron sufficiency. Chromate shock resulted in transient induction/enhancement of six proteins. Cultures grown with chromate stress, however, did not show any of the transiently induced proteins but revealed notable inhibition of one protein. (C) Elsevier, Paris."
1578137,Kim et al. 2002,Oxidation of chromium(III) to (VI) by manganese oxides,"Manganese oxides in soils oxidize Cr from a stable form to a more toxic mobile form. The influence of Mu oxide diversity on Cr oxidation is the subject of this report. Oxidation of Cr(111) to Cr(VI) by coarse clay-size natural Mn oxides, birnessite, todorokite, and lithiophorite was studied at pH 4 and 7, and at 200 and 400 muM initial Cr(Ill) concentrations. The oxidation rate obeyed the first-order rate law at the 400 muM Cr(III) initial concentration; the 200 muM concentration was too low and reverse reactions may have interfered. Rate law is valid only far from equilibrium. The rate of oxidation was greater for todorokite and birnessite that contained the most quadrivalent Mn and least for lithiophorite that contained a greater proportion of trivalent Mn determined by x-ray photoelectron spectroscopy (XPS). The deviation of Mn oxidation state from the frequently assumed quadrivalent form in Mn oxides suggests the need for a thorough assessment of the ion species of Mn in Mn oxides that occur in soils. At 400 muM Cr(III), the rate of Cr oxidation by the pyrolusite sample was intermediate between birnessite and todorokite suggesting that the sample was not pure pyrolusite. Apparently, the synthesis process did not reach equilibrium with pyrolusite. The sample used as a chemical standard was apparently more soluble and more effective in oxidizing Cr(III) than would be expected for the natural mineral pyrolusite.","Oxidation of chromium(III) to (VI) by manganese oxides Abs: Manganese oxides in soils oxidize Cr from a stable form to a more toxic mobile form. The influence of Mu oxide diversity on Cr oxidation is the subject of this report. Oxidation of Cr(111) to Cr(VI) by coarse clay-size natural Mn oxides, birnessite, todorokite, and lithiophorite was studied at pH 4 and 7, and at 200 and 400 muM initial Cr(Ill) concentrations. The oxidation rate obeyed the first-order rate law at the 400 muM Cr(III) initial concentration; the 200 muM concentration was too low and reverse reactions may have interfered. Rate law is valid only far from equilibrium. The rate of oxidation was greater for todorokite and birnessite that contained the most quadrivalent Mn and least for lithiophorite that contained a greater proportion of trivalent Mn determined by x-ray photoelectron spectroscopy (XPS). The deviation of Mn oxidation state from the frequently assumed quadrivalent form in Mn oxides suggests the need for a thorough assessment of the ion species of Mn in Mn oxides that occur in soils. At 400 muM Cr(III), the rate of Cr oxidation by the pyrolusite sample was intermediate between birnessite and todorokite suggesting that the sample was not pure pyrolusite. Apparently, the synthesis process did not reach equilibrium with pyrolusite. The sample used as a chemical standard was apparently more soluble and more effective in oxidizing Cr(III) than would be expected for the natural mineral pyrolusite."
1578136,Kishore et al. 2007,Effect of sodium dodecyl sulphate micelles on the oxidation of L-methionine by chromium(VI) in perchloric acid medium,"The kinetics of oxidation of methionine by chromium(VI) in presence of an anionic surfactant, sodium dodecyl sulphate (SDS) has been studied under pseudo-first order conditions in perchloric acid medium. It was found that increase in [SDS] causes a decrease In rate indicating that the reaction is inhibited by anionic micelles. The critical micelle concentration (CMC) for SDS has been determined in 0.2 mol dm(-3) ionic strength in presence of the oxidant by surface tension measurements and found to be 4 x 10(-4) mol dm(-3). Further, the reaction is first order in [chromium(VI)], [methionine] and [H+]. Methionine sulphoxide is identified to be the main product of oxidation.","Effect of sodium dodecyl sulphate micelles on the oxidation of L-methionine by chromium(VI) in perchloric acid medium Abs: The kinetics of oxidation of methionine by chromium(VI) in presence of an anionic surfactant, sodium dodecyl sulphate (SDS) has been studied under pseudo-first order conditions in perchloric acid medium. It was found that increase in [SDS] causes a decrease In rate indicating that the reaction is inhibited by anionic micelles. The critical micelle concentration (CMC) for SDS has been determined in 0.2 mol dm(-3) ionic strength in presence of the oxidant by surface tension measurements and found to be 4 x 10(-4) mol dm(-3). Further, the reaction is first order in [chromium(VI)], [methionine] and [H+]. Methionine sulphoxide is identified to be the main product of oxidation."
1578135,Kousalya et al. 2010,Removal of Toxic Cr(VI) Ions from Aqueous Solution Using Nano-hydroxyapatite-based Chitin and Chitosan Hybrid Composites,"In the present investigation, bio-inorganic composites composed of nano-hydroxyapatite (n-HAp) with chitin and chitosan have been prepared and used for the removal of chromium(VI) ions from aqueous solution. Such composites exhibited a higher Cr(VI) ion sorption capacity than the individual components. The sorption capacities of n-HAp, n-HAp/chitin (n-HApC) composite and n-HAp/chitosan (n-HApCs) composite were found to be 2720, 2845 and 3450 mg/kg, respectively. Batch adsorption studies were conducted to optimize various equilibrating conditions such as the contact time, pH and co-ions. The sorbents were characterized by FT-IR spectroscopy, BET and EDXA analysis. The sorption process could be fitted by both the Freundlich and Langmuir isotherm models. Standard thermodynamic parameters such as the Gibbs' free energy change, Delta G(0), the standard enthalpy change, Delta H(0), and the standard entropy change, Delta S(0), were calculated in order to obtain an understanding of the nature of the sorption process. The kinetics of the reaction could be fitted by the pseudo-second-order and intra-particle diffusion models. The mechanism for Cr(VI) ion sorption onto the composites was established.","Removal of Toxic Cr(VI) Ions from Aqueous Solution Using Nano-hydroxyapatite-based Chitin and Chitosan Hybrid Composites Abs: In the present investigation, bio-inorganic composites composed of nano-hydroxyapatite (n-HAp) with chitin and chitosan have been prepared and used for the removal of chromium(VI) ions from aqueous solution. Such composites exhibited a higher Cr(VI) ion sorption capacity than the individual components. The sorption capacities of n-HAp, n-HAp/chitin (n-HApC) composite and n-HAp/chitosan (n-HApCs) composite were found to be 2720, 2845 and 3450 mg/kg, respectively. Batch adsorption studies were conducted to optimize various equilibrating conditions such as the contact time, pH and co-ions. The sorbents were characterized by FT-IR spectroscopy, BET and EDXA analysis. The sorption process could be fitted by both the Freundlich and Langmuir isotherm models. Standard thermodynamic parameters such as the Gibbs' free energy change, Delta G(0), the standard enthalpy change, Delta H(0), and the standard entropy change, Delta S(0), were calculated in order to obtain an understanding of the nature of the sorption process. The kinetics of the reaction could be fitted by the pseudo-second-order and intra-particle diffusion models. The mechanism for Cr(VI) ion sorption onto the composites was established."
1578134,Kozlowski et al. 2002,Competitive transport of toxic metal ions by polymer inclusion membranes,"The paper gives a short overview of application of polymer inclusion membranes (PIMs) for separation and removal of metal ions. Investigation of the selective removal of toxic metal ions, i.e. Cr(VI), Cd(II), Zn(II) from acidic chloride aqueous solutions, as well as trace radionuclides, i.e., Cs-137, Sr-90 and Co-60 from wastewaters using transport across polymer inclusion membranes was studied. The carriers, i.e., tri-n-octylamine for anionic metal species, as well as dibenzo-21-crown-7, tertbutyl-dibenzo-21-crown-7, and dinonylnaphtalenesulfonic acid for metal cations were incorporated into polymer inclusion membranes composed of cellulose triacetate as a support and o-nitrophenyl pentyl ether as a plasticizer. Selective transport of chromium(VI) over zinc(II) and cadmium(II) chloride complexes through PIMs was observed. Competitive transport of trace radionuclide ions, i.e., Cs-137, Sr-90, and Co-60 from NaNO3 aqueous solutions across polymer inclusion membranes containing a mixture of dinonylnaphtalenesulfonic acid, and dibenzo-21-crown-7 as the carrier provide the selectivity order Cs(I)>Sr(II)>Co(II).","Competitive transport of toxic metal ions by polymer inclusion membranes Abs: The paper gives a short overview of application of polymer inclusion membranes (PIMs) for separation and removal of metal ions. Investigation of the selective removal of toxic metal ions, i.e. Cr(VI), Cd(II), Zn(II) from acidic chloride aqueous solutions, as well as trace radionuclides, i.e., Cs-137, Sr-90 and Co-60 from wastewaters using transport across polymer inclusion membranes was studied. The carriers, i.e., tri-n-octylamine for anionic metal species, as well as dibenzo-21-crown-7, tertbutyl-dibenzo-21-crown-7, and dinonylnaphtalenesulfonic acid for metal cations were incorporated into polymer inclusion membranes composed of cellulose triacetate as a support and o-nitrophenyl pentyl ether as a plasticizer. Selective transport of chromium(VI) over zinc(II) and cadmium(II) chloride complexes through PIMs was observed. Competitive transport of trace radionuclide ions, i.e., Cs-137, Sr-90, and Co-60 from NaNO3 aqueous solutions across polymer inclusion membranes containing a mixture of dinonylnaphtalenesulfonic acid, and dibenzo-21-crown-7 as the carrier provide the selectivity order Cs(I)>Sr(II)>Co(II)."
1578133,Kraus et al. 1998,"Acute toxicity of potassium dichromate, sodium dodecyl sulfate, copper and zinc to Poecilia vivipara (Osteichthyes, Cyprinodontiformes)","The sensibility of Poecilia vivipara to four reference substances (potassium dichromate, sodium dodecyl sulfate (SDS), copper and zinc) was investigated, and the suitability of this species in toxicity tests was verified. P, vivipara was more sensitive to copper and less sensitive to zinc. Coefficients of variation obtained in tests with dichromate and SDS were lower than with copper and zinc. The coefficients between test results are similar to those found in the literature for other species. The results indicated that P. vivipara is a species which is suitable for toxicity tests.","Acute toxicity of potassium dichromate, sodium dodecyl sulfate, copper and zinc to Poecilia vivipara (Osteichthyes, Cyprinodontiformes) Abs: The sensibility of Poecilia vivipara to four reference substances (potassium dichromate, sodium dodecyl sulfate (SDS), copper and zinc) was investigated, and the suitability of this species in toxicity tests was verified. P, vivipara was more sensitive to copper and less sensitive to zinc. Coefficients of variation obtained in tests with dichromate and SDS were lower than with copper and zinc. The coefficients between test results are similar to those found in the literature for other species. The results indicated that P. vivipara is a species which is suitable for toxicity tests."
1578109,Julian et al. 2002,A study of the method of synthesis and chromatic properties of the Cr-SnO(2) pigment,,A study of the method of synthesis and chromatic properties of the Cr-SnO(2) pigment Abs: 
1578108,Kabir-ud-Din et al. 2000,Unusual rate inhibition of manganese(II) assisted oxidation of citric acid by chromium(VI) in the presence of ionic micelles,,Unusual rate inhibition of manganese(II) assisted oxidation of citric acid by chromium(VI) in the presence of ionic micelles Abs: 
1578107,Kabir-ud-Din et al. 2001,Effect of micelles on the oxidation of oxalic acid by chromium(VI) in the presence and absence of manganese(II),,Effect of micelles on the oxidation of oxalic acid by chromium(VI) in the presence and absence of manganese(II) Abs: 
1578106,Kabir-ud-Din et al. 2002,Co-oxidation of malic acid and manganese(II) by chromium(VI) in the presence and absence of ionic surfactants,,Co-oxidation of malic acid and manganese(II) by chromium(VI) in the presence and absence of ionic surfactants Abs: 
1578105,Kabir-ud-Din et al. 2001,Chromic acid oxidation of organic acids in CTAB-n-heptane-water-1-pentanol microemulsion,,Chromic acid oxidation of organic acids in CTAB-n-heptane-water-1-pentanol microemulsion Abs: 
1578104,Kabir-ud-Din et al. 2004,Redox behaviour of chromium(VI) towards D-mannose in the presence and absence of micelles and inorganic salts,,Redox behaviour of chromium(VI) towards D-mannose in the presence and absence of micelles and inorganic salts Abs: 
1578103,Kabir-Ud-Din et al. 2001,Micellar effects on the chromium(VI) oxidation of D(+)-xylose,,Micellar effects on the chromium(VI) oxidation of D(+)-xylose Abs: 
1578102,Kabir-ud-Din et al. 2003,Oxidative degradation of L(+)arabinose by chromium(VI) in absence and presence of sodium dodecyl sulphate and TX-100 micelles,,Oxidative degradation of L(+)arabinose by chromium(VI) in absence and presence of sodium dodecyl sulphate and TX-100 micelles Abs: 
1578101,Jardine et al. 1999,Fate and transport of hexavalent chromium in undisturbed heterogeneous soil,"BIOSIS COPYRIGHT: BIOL ABS. The disposal of toxic metals (e.g., Cr(VI)) generated by the Department of Energy during the cold war era has historically involved shallow land burial in unconfined pits and trenches. The objectives of this study were to investigate the impact of coupled hydrologic and geochemical processes on the fate and transport of Cr(VI) in undisturbed soil cores obtained from a fractured, acidic inceptisol that are commonly used in the disposal of waste at the Oak Ridge National Laboratory. The mobility o Cr(III) was dramatically more significant on soils with higher levels of surface-bound NOM. Thisindicated that NOM was serving as a suitable reductant during Cr(VI) transport even in the presence of potentially competing geochemical oxidation reactions involving Cr. The redox reaction was catalyzed by the presence of soil mineral surfaces, and the reduced product Cr(III) was immobilized as a tightly bound moiety. The effectiveness of surface-bound NOM to reduce toxic Cr(VI) to Cr(III) under acid","Fate and transport of hexavalent chromium in undisturbed heterogeneous soil Abs: BIOSIS COPYRIGHT: BIOL ABS. The disposal of toxic metals (e.g., Cr(VI)) generated by the Department of Energy during the cold war era has historically involved shallow land burial in unconfined pits and trenches. The objectives of this study were to investigate the impact of coupled hydrologic and geochemical processes on the fate and transport of Cr(VI) in undisturbed soil cores obtained from a fractured, acidic inceptisol that are commonly used in the disposal of waste at the Oak Ridge National Laboratory. The mobility o Cr(III) was dramatically more significant on soils with higher levels of surface-bound NOM. Thisindicated that NOM was serving as a suitable reductant during Cr(VI) transport even in the presence of potentially competing geochemical oxidation reactions involving Cr. The redox reaction was catalyzed by the presence of soil mineral surfaces, and the reduced product Cr(III) was immobilized as a tightly bound moiety. The effectiveness of surface-bound NOM to reduce toxic Cr(VI) to Cr(III) under acid"
1578100,Islam and  Bhowmik 2005,Toxicopathogenic effect of hexavalent chromium(VI) in chickens,,Toxicopathogenic effect of hexavalent chromium(VI) in chickens Abs: 
1578099,Hori et al. 2009,"SENSITIVE ACUTE TOXICITY TESTING IN TWO MARINE SHRIMP SPECIES: COLLECTION AND REARING OF LARVAE, AND CHANGES OF ACUTE TOXICITY VALUES DURING LARVAL DEVELOPMENT",,"SENSITIVE ACUTE TOXICITY TESTING IN TWO MARINE SHRIMP SPECIES: COLLECTION AND REARING OF LARVAE, AND CHANGES OF ACUTE TOXICITY VALUES DURING LARVAL DEVELOPMENT Abs: "
1578098,Hayashi and  Kashiwagi 2010,A Bayesian Method for Deriving Species-Sensitivity Distributions: Selecting the Best-Fit Tolerance Distributions of Taxonomic Groups,,A Bayesian Method for Deriving Species-Sensitivity Distributions: Selecting the Best-Fit Tolerance Distributions of Taxonomic Groups Abs: 
1578097,Hamid et al. 2009,Synthesis and Characterization of Amino-functionalized Mesoporous Silicate MCM-41 for Removal of Toxic Metal Ions,,Synthesis and Characterization of Amino-functionalized Mesoporous Silicate MCM-41 for Removal of Toxic Metal Ions Abs: 
1578096,Gutierrez et al. 2008,"Bioconcentration and trophic transfer of chromium in the Daphnia magna (Crustaceae : Cladocera)-Cnesterodon decemmaculatus (Pisces, Poeciliidae) system",,"Bioconcentration and trophic transfer of chromium in the Daphnia magna (Crustaceae : Cladocera)-Cnesterodon decemmaculatus (Pisces, Poeciliidae) system Abs: "
1578095,Gurbuz 2009,Removal of Toxic Hexavalent Chromium Ions from Aqueous Solution by a Natural Biomaterial: Batch and Column Adsorption,,Removal of Toxic Hexavalent Chromium Ions from Aqueous Solution by a Natural Biomaterial: Batch and Column Adsorption Abs: 
1578092,Hug et al. 1997,Transformations of chromium in the environment,"BIOSIS COPYRIGHT: BIOL ABS. Reduction of toxic Cr(VI) to non-toxic Cr(III) in the environment is a desirable, but potentially reversible, process. An important natural reductant is Fe(II), suggested oxidants are manganese oxides. Redox reactions with Cr are largely kinetically controlled: pH, organic ligands and surfaces strongly influence rates and reaction pathways. This paper presents laboratory studies in homogeneous and heterogeneous model systems containing Cr(VI) and Fe(II), using three in situ techniques: multicomponent UV-VIS, FTIR and AFM.","Transformations of chromium in the environment Abs: BIOSIS COPYRIGHT: BIOL ABS. Reduction of toxic Cr(VI) to non-toxic Cr(III) in the environment is a desirable, but potentially reversible, process. An important natural reductant is Fe(II), suggested oxidants are manganese oxides. Redox reactions with Cr are largely kinetically controlled: pH, organic ligands and surfaces strongly influence rates and reaction pathways. This paper presents laboratory studies in homogeneous and heterogeneous model systems containing Cr(VI) and Fe(II), using three in situ techniques: multicomponent UV-VIS, FTIR and AFM."
1578091,Wolf et al. 1998,The role of combination effects on the etiology of malignant nasal tumours in the wood-working industry - Most recent findings and analysis of 147 indemnified cases of adenocarcinomas,,The role of combination effects on the etiology of malignant nasal tumours in the wood-working industry - Most recent findings and analysis of 147 indemnified cases of adenocarcinomas Abs: 
1578090,Yuan et al. 2006,Radiation-induced reduction of chromium(VI) in aqueous solution by gamma-irradiation in a laboratory-scale,,Radiation-induced reduction of chromium(VI) in aqueous solution by gamma-irradiation in a laboratory-scale Abs: 
1578089,Zarras et al. 2011,ELECTROACTIVE MATERIALS as Smart Corrosion-Inhibiting Coatings for the Replacement of Hexavalent Chromium,,ELECTROACTIVE MATERIALS as Smart Corrosion-Inhibiting Coatings for the Replacement of Hexavalent Chromium Abs: 
1578088,Zhu et al. 2012,REMOVAL OF Cr(VI) BY MODIFIED EXPANDED GRAPHITE USING RESPONSE SURFACE METHODOLOGY,,REMOVAL OF Cr(VI) BY MODIFIED EXPANDED GRAPHITE USING RESPONSE SURFACE METHODOLOGY Abs: 
1578085,Whalley et al. 1999,"Chromium speciation in natural waters draining contaminated land, Glasgow, U.K","BIOSIS COPYRIGHT: BIOL ABS. Historically, solid waste from chromite ore processing has been disposed of at a number of sites in Glasgow, Scotland. Leachate from these sites has been implicated as a source of chromium (Cr) contamination to both groundwaters and stream waters in the south east area of the city. In this study, chromium speciation has been determined in ground-, stream-, river- and pore waters, to assess the extent of contamination and the associated risk. The speciation of chromium is important, as the trival s and streamwaters in the area immediately surrounding the contaminated sites, and high concentrations of chromium were also found in River Clyde sediments downstream of these sites. However, these concentrations rapidly decrease away from the chromium-contaminated south eastern side of the city. Data from porewaters suggest that some reduction of Cr(VI) occurs naturally in the sediments, indicating that the risk posed by high concentrations of Cr(VI) should be decreased over the","Chromium speciation in natural waters draining contaminated land, Glasgow, U.K Abs: BIOSIS COPYRIGHT: BIOL ABS. Historically, solid waste from chromite ore processing has been disposed of at a number of sites in Glasgow, Scotland. Leachate from these sites has been implicated as a source of chromium (Cr) contamination to both groundwaters and stream waters in the south east area of the city. In this study, chromium speciation has been determined in ground-, stream-, river- and pore waters, to assess the extent of contamination and the associated risk. The speciation of chromium is important, as the trival s and streamwaters in the area immediately surrounding the contaminated sites, and high concentrations of chromium were also found in River Clyde sediments downstream of these sites. However, these concentrations rapidly decrease away from the chromium-contaminated south eastern side of the city. Data from porewaters suggest that some reduction of Cr(VI) occurs naturally in the sediments, indicating that the risk posed by high concentrations of Cr(VI) should be decreased over the"
1578084,Zhang and  Bartlett 1999,Light-induced oxidation of aqueous chromium(III) in the presence of iron(III),"BIOSIS COPYRIGHT: BIOL ABS. Oxidation of Cr(III) to toxic Cr(VI) by Mn(IV) or Mn(III) species has been identified as probably the only important oxidation pathway in soils, aquatic bodies, and atmospheric environments-We observed ready oxidation of Cr(III) in Fe(111) solutions in light at pH 3.2-4.4. Further kinetic study of this oxidation was performed in sunlight as well as in black light under controlled conditions (e.g., pH 3.2, 20'C). Quantum yields of Cr(VI) formation at 356 nm were 0.020- 0.046 for initial levels of 50-800 muM Cr(III) and 200 muM Fe- (111). The Cr(VI) formation reached steady state in 0.5 h (6 muM, (Cr(III))0: 50 muM; 10 muM, (Cr(III))0: 200 muM; (Fe(III))0: 200 muM). The best linearity found only for log(Cr(III)) vs tin the first 1 or 1.5 min of the reaction suggests apparent first-order kinetics for the disappearance of Cr(III) at 356 nm over the period; afterward, it failed to comply with any regular rate law. The Cr(III) oxidation decreased at high initial levels of Cr(Zhang, H, Bartlett, RJ, 1999","Light-induced oxidation of aqueous chromium(III) in the presence of iron(III) Abs: BIOSIS COPYRIGHT: BIOL ABS. Oxidation of Cr(III) to toxic Cr(VI) by Mn(IV) or Mn(III) species has been identified as probably the only important oxidation pathway in soils, aquatic bodies, and atmospheric environments-We observed ready oxidation of Cr(III) in Fe(111) solutions in light at pH 3.2-4.4. Further kinetic study of this oxidation was performed in sunlight as well as in black light under controlled conditions (e.g., pH 3.2, 20'C). Quantum yields of Cr(VI) formation at 356 nm were 0.020- 0.046 for initial levels of 50-800 muM Cr(III) and 200 muM Fe- (111). The Cr(VI) formation reached steady state in 0.5 h (6 muM, (Cr(III))0: 50 muM; 10 muM, (Cr(III))0: 200 muM; (Fe(III))0: 200 muM). The best linearity found only for log(Cr(III)) vs tin the first 1 or 1.5 min of the reaction suggests apparent first-order kinetics for the disappearance of Cr(III) at 356 nm over the period; afterward, it failed to comply with any regular rate law. The Cr(III) oxidation decreased at high initial levels of Cr(Zhang, H, Bartlett, RJ, 1999"
1578080,Costa et al. 2004,Effects of different Cr(VI) exposures on the viability and growth rates of PC 12 cultures,"Epidemiological, animal and cellular studies have established that Cr(VI) compounds are carcinogenic and that environmental and occupational exposure to Cr(VI) constitutes a significant health risk. In an attempt to define mechanisms underlying Cr(VI)-induced carcinogenesis, we exposed cultures of PC12 cells to different Cr(VI) insults (2, 9 and 20 mM; 2, 6 and 24 h) and determined the effects of those exposures on relevant cellular parameters. For the stronger exposures, a decrease in the total number of viable cells was observed. For the 24 h exposures (9 and 20 mu M), this decrease could be partly explained by an increase in cell death. This increased cell death was likely the result of an observed decrease in ATP levels and of a perturbation on the cellular redox status, as indicated by an increase in reactive oxygen species and in peroxidation levels. Oxidative stress and mitochondria were thus implicated in the mechanisms underlying this toxic effect. Interestingly, after exposing cultures to an insult that had no effect on the total number of viable cells (2 mu M; 24 h), a decrease in cell proliferation Could be observed for some time after the removal of the insult, thus suggesting that small sub-lethal concentrations of Cr(VI), which are potentially relevant to environmental and occupational exposures, may delay DNA replication and mitosis.","Effects of different Cr(VI) exposures on the viability and growth rates of PC 12 cultures Abs: Epidemiological, animal and cellular studies have established that Cr(VI) compounds are carcinogenic and that environmental and occupational exposure to Cr(VI) constitutes a significant health risk. In an attempt to define mechanisms underlying Cr(VI)-induced carcinogenesis, we exposed cultures of PC12 cells to different Cr(VI) insults (2, 9 and 20 mM; 2, 6 and 24 h) and determined the effects of those exposures on relevant cellular parameters. For the stronger exposures, a decrease in the total number of viable cells was observed. For the 24 h exposures (9 and 20 mu M), this decrease could be partly explained by an increase in cell death. This increased cell death was likely the result of an observed decrease in ATP levels and of a perturbation on the cellular redox status, as indicated by an increase in reactive oxygen species and in peroxidation levels. Oxidative stress and mitochondria were thus implicated in the mechanisms underlying this toxic effect. Interestingly, after exposing cultures to an insult that had no effect on the total number of viable cells (2 mu M; 24 h), a decrease in cell proliferation Could be observed for some time after the removal of the insult, thus suggesting that small sub-lethal concentrations of Cr(VI), which are potentially relevant to environmental and occupational exposures, may delay DNA replication and mitosis."
1578079,Schmitt et al. 2005,Assessment of Cyto- and Genotoxic Effects of a Variety of Chemicals UsingSaccharomyces cerevisiae,,Assessment of Cyto- and Genotoxic Effects of a Variety of Chemicals UsingSaccharomyces cerevisiae Abs: 
1578078,Nath and  Kumar 1987,Toxic Impact of Hexavalent Chromium on the BLOOD Pyruvate of Colisa fasciatus,,Toxic Impact of Hexavalent Chromium on the BLOOD Pyruvate of Colisa fasciatus Abs: 
1578077,Liu et al. 2012,Synthesis and characterization of nanostructured Fe3O4 micron-spheres and their application in removing toxic Cr ions from polluted water,"We present a simple and effective method for the synthesis of nanostructured Fe(3)O(4) micron-spheres (NFMSs) by annealing hydrothermally formed FeCO(3) spheres in argon. The phase structure, particle size, and magnetic properties of the product have been characterized by X-ray diffraction (XRD), Fourier-transform infrared spectroscopy (FTIR), X-ray photoelectron spectroscopy (XPS), field-emission scanning electron microscopy (FESEM), transmission electron microscopy (TEM), and by means of a superconducting quantum interference device (SQUID). The results have shown that the as-obtained NFMSs have a diameter of about 5 ?m and are composed of nanometer-sized porous lamellae. The NFMSs have a large specific surface area (135.9 m(2) g(-1)), reductive Fe(2+) incorporated into their structure, and intense magnetic properties. These properties suggest that NFMSs have potential application in removing toxic Cr(6+) ions from polluted water. At 25°C, each gram of NFMSs product can remove 43.48 mg of Cr(6+) ions, as compared to just 10.2 mg for nanometer-sized Fe(3)O(4) and 1.89 mg for micron-sized Fe(3)O(4). The enhanced removal performance can be ascribed to the structural features. Moreover, the Cr(6+) ion removal capacity of the NFMSs can reach up to 71.2 mg g(-1) at 50°C. The influencing parameters in the removal of Cr(6+) ions, such as contact time, pH, and temperature, have been evaluated. The Cr(6+)-removal mechanism has been investigated. We have found that the NFMSs product not only serves as an effective adsorbent to remove toxic Cr(6+) ions from polluted water, but also as an effective reductant in reducing the adsorbed toxic Cr(6+) ions to much less toxic Cr(3+) through the Fe(2+) incorporated into its structure.","Synthesis and characterization of nanostructured Fe3O4 micron-spheres and their application in removing toxic Cr ions from polluted water Abs: We present a simple and effective method for the synthesis of nanostructured Fe(3)O(4) micron-spheres (NFMSs) by annealing hydrothermally formed FeCO(3) spheres in argon. The phase structure, particle size, and magnetic properties of the product have been characterized by X-ray diffraction (XRD), Fourier-transform infrared spectroscopy (FTIR), X-ray photoelectron spectroscopy (XPS), field-emission scanning electron microscopy (FESEM), transmission electron microscopy (TEM), and by means of a superconducting quantum interference device (SQUID). The results have shown that the as-obtained NFMSs have a diameter of about 5 ?m and are composed of nanometer-sized porous lamellae. The NFMSs have a large specific surface area (135.9 m(2) g(-1)), reductive Fe(2+) incorporated into their structure, and intense magnetic properties. These properties suggest that NFMSs have potential application in removing toxic Cr(6+) ions from polluted water. At 25°C, each gram of NFMSs product can remove 43.48 mg of Cr(6+) ions, as compared to just 10.2 mg for nanometer-sized Fe(3)O(4) and 1.89 mg for micron-sized Fe(3)O(4). The enhanced removal performance can be ascribed to the structural features. Moreover, the Cr(6+) ion removal capacity of the NFMSs can reach up to 71.2 mg g(-1) at 50°C. The influencing parameters in the removal of Cr(6+) ions, such as contact time, pH, and temperature, have been evaluated. The Cr(6+)-removal mechanism has been investigated. We have found that the NFMSs product not only serves as an effective adsorbent to remove toxic Cr(6+) ions from polluted water, but also as an effective reductant in reducing the adsorbed toxic Cr(6+) ions to much less toxic Cr(3+) through the Fe(2+) incorporated into its structure."
1578076,Wasewar et al. 2008,"Adsorption of Zinc using Tea Factory Waste: Kinetics, Equilibrium and Thermodynamics",,"Adsorption of Zinc using Tea Factory Waste: Kinetics, Equilibrium and Thermodynamics Abs: "
1578075,Pamplin and  Johnson 1997,The coulometric determination of chemical oxygen demand,,The coulometric determination of chemical oxygen demand Abs: 
1578074,Jacobs 1992,Treatment and stabilization of a hexavalent chromium containing waste material,,Treatment and stabilization of a hexavalent chromium containing waste material Abs: 
1578073,Nomikou et al. 2006,Use of an electric field-assisted biosorption process in the removal of hazardous or precious ionic species from wastewater streams,,Use of an electric field-assisted biosorption process in the removal of hazardous or precious ionic species from wastewater streams Abs: 
1578072,Humphries et al. 2007,Cr(VI) reduction by bio and bioinorganic catalysis via use of bio-H2: a sustainable approach for remediation of wastes,,Cr(VI) reduction by bio and bioinorganic catalysis via use of bio-H2: a sustainable approach for remediation of wastes Abs: 
1578071,Remoundaki et al. 2007,A systematic study of chromium solubility in the presence of organic matter: consequences for the treatment of chromium-containing wastewater,,A systematic study of chromium solubility in the presence of organic matter: consequences for the treatment of chromium-containing wastewater Abs: 
1578070,Kabir-ud-din et al. 2001,Micellar catalysis on the redox reaction of glycolic acid with chromium(VI),,Micellar catalysis on the redox reaction of glycolic acid with chromium(VI) Abs: 
1578068,Islam et al. 2006,"Chromic acid oxidation of hexitols in the presence of 2,2?-bipyridyl catalyst in aqueous micellar media: A kinetic study",,"Chromic acid oxidation of hexitols in the presence of 2,2?-bipyridyl catalyst in aqueous micellar media: A kinetic study Abs: "
1578067,Patel and  Mishra 2006,A novel lipopathic Cr(VI) oxidant for organic substrates: Kinetic study of oxidation of benzyl alcohol,,A novel lipopathic Cr(VI) oxidant for organic substrates: Kinetic study of oxidation of benzyl alcohol Abs: 
1578066,Saha et al. 2008,Micellar effect on quinquivalent vanadium ion oxidation ofD-glucose in aqueous acid media: A kinetic study,,Micellar effect on quinquivalent vanadium ion oxidation ofD-glucose in aqueous acid media: A kinetic study Abs: 
1578064,Sarkar et al. 1995,Comparison of the effects of crude extract of spinach-beet leaves and equivalent amounts of chlorophyll and chlorophyllin in modifying the clastogenic activity of chromium (VI) oxide in micein vivo,,Comparison of the effects of crude extract of spinach-beet leaves and equivalent amounts of chlorophyll and chlorophyllin in modifying the clastogenic activity of chromium (VI) oxide in micein vivo Abs: 
1578063,Hörnström et al. 1993,Surface study of a chromate pretreatment before coil coating of Al-43.4Zn-1.6Si coated steel,,Surface study of a chromate pretreatment before coil coating of Al-43.4Zn-1.6Si coated steel Abs: 
1578062,Kallithrakas-Kontos et al. 2009,Chromium speciation by TXRF analysis,,Chromium speciation by TXRF analysis Abs: 
1578061,Sógor et al. 1998,Flame Atomic Absorption Spectrometric Determination of Total Chromium and Cr(VI) in Cigarette Ash and Smoke using Flow Injection/Hydraulic High-Pressure Sample Introduction,,Flame Atomic Absorption Spectrometric Determination of Total Chromium and Cr(VI) in Cigarette Ash and Smoke using Flow Injection/Hydraulic High-Pressure Sample Introduction Abs: 
1578060,Lakshmi et al. 1996,Mechanism of oxidation of iron(II) chelates by hexavalent chromium and heptavalent manganese in aqueous sulfuric acid and micellar media - a kinetic approach,,Mechanism of oxidation of iron(II) chelates by hexavalent chromium and heptavalent manganese in aqueous sulfuric acid and micellar media - a kinetic approach Abs: 
1578059,Venugopal et al. 1993,In vivo effects of trivalent and hexavalent chromium on renal and hepatic atpases of a freshwater teleost Anabas scandens,"The in vivo toxic effect of trivalent and hexavalent chromium (25 mg/L) on the renal and hepatic tissue ATPases of an edible teleost Anabas scandens was studied. In an exposure span of 30 days Na(+)-K(+) ATPase activity exhibited a progressive inhibition in the kidney, but marked inhibition in Na(+)-K(+) ATPase activity was observed in the liver. Mg(2+) ATPase activity, however, exhibited an elevation on early exposures, with a later inhibition.","In vivo effects of trivalent and hexavalent chromium on renal and hepatic atpases of a freshwater teleost Anabas scandens Abs: The in vivo toxic effect of trivalent and hexavalent chromium (25 mg/L) on the renal and hepatic tissue ATPases of an edible teleost Anabas scandens was studied. In an exposure span of 30 days Na(+)-K(+) ATPase activity exhibited a progressive inhibition in the kidney, but marked inhibition in Na(+)-K(+) ATPase activity was observed in the liver. Mg(2+) ATPase activity, however, exhibited an elevation on early exposures, with a later inhibition."
1578058,Kachurina et al. 2002,Comparison of single and multilayer coatings based on ormosil and conversion layers for aluminum alloy corrosion inhibition,,Comparison of single and multilayer coatings based on ormosil and conversion layers for aluminum alloy corrosion inhibition Abs: 
1578057,Kim et al. 2002,Reduction of hexavalent chromium by pyrite-rich andesite in different anionic solutions,,Reduction of hexavalent chromium by pyrite-rich andesite in different anionic solutions Abs: 
1578056,Yang et al. 2008,Interaction between Cr(VI) and a Fe-rich soil in the presence of oxalic and tartaric acids,,Interaction between Cr(VI) and a Fe-rich soil in the presence of oxalic and tartaric acids Abs: 
1578055,Kabir-ud-din et al. 2006,Kinetics of the oxidative degradation of d-xylose in the presence and absence of cationic and anionic surfactants,,Kinetics of the oxidative degradation of d-xylose in the presence and absence of cationic and anionic surfactants Abs: 
1578054,Majidi and  Shemirani 2012,Salt-assisted liquid-liquid microextraction of Cr(VI) ion using an ionic liquid for preconcentration prior to its determination by flame atomic absorption spectrometry,,Salt-assisted liquid-liquid microextraction of Cr(VI) ion using an ionic liquid for preconcentration prior to its determination by flame atomic absorption spectrometry Abs: 
1578053,Rezi? and  Zeiner 2009,Determination of extractable chromium from leather,,Determination of extractable chromium from leather Abs: 
1578052,Rivero-Huguet and  Marshall 2008,Uncertainties when using dual-wavelength or single-wavelength spectrophotometry to monitor the course of hexavalent chromium reduction mediated by zero-valent iron,,Uncertainties when using dual-wavelength or single-wavelength spectrophotometry to monitor the course of hexavalent chromium reduction mediated by zero-valent iron Abs: 
1578051,Pilbáth et al. 2006,Application of self-assembly for replacing chromate in corrosion protection of zinc,,Application of self-assembly for replacing chromate in corrosion protection of zinc Abs: 
1578050,Mohamad et al. 2012,Biosorption and Bioaccumulation of Cu2+ from Aqueous Solution Using Living M. amorphae Isolated from Mine Tailings,,Biosorption and Bioaccumulation of Cu2+ from Aqueous Solution Using Living M. amorphae Isolated from Mine Tailings Abs: 
1578049,Ruotolo and  Liao 2004,Reaction rate and electrochemical stability of conducting polymer films used for the reduction of hexavalent chromium,,Reaction rate and electrochemical stability of conducting polymer films used for the reduction of hexavalent chromium Abs: 
1578048,Gustavsson et al. 2010,Rare earth metal salts as potential alternatives to Cr(VI) in the chlorate process,,Rare earth metal salts as potential alternatives to Cr(VI) in the chlorate process Abs: 
1578047,Survilien? et al. 2011,Chromium electrodeposition from [BMIm][BF4] ionic liquid,,Chromium electrodeposition from [BMIm][BF4] ionic liquid Abs: 
1578046,Tayeb et al. 2005,Effect of Surfactants on the Behavior of Chromium in Analytical Flame Atomic Absorption Spectrometry,,Effect of Surfactants on the Behavior of Chromium in Analytical Flame Atomic Absorption Spectrometry Abs: 
1578045,Saha et al. 2008,Micellar Catalysis on Pentavalent Vanadium Ion Oxidation of D-Sorbitol in Aqueous Acid Media: A Kinetic Study,,Micellar Catalysis on Pentavalent Vanadium Ion Oxidation of D-Sorbitol in Aqueous Acid Media: A Kinetic Study Abs: 
1578044,Yusof et al. 2007,Speciation of Cr(III) and Cr(VI) in surface waters with a Chelex-100 resin column and their quantitative determination using inductively coupled plasma mass spectrometry and instrumental neutron activation analysis,,Speciation of Cr(III) and Cr(VI) in surface waters with a Chelex-100 resin column and their quantitative determination using inductively coupled plasma mass spectrometry and instrumental neutron activation analysis Abs: 
1578043,Liu et al. 2007,Microcalorimetry as a tool for Cr(VI) toxicity evaluation of human dermal fibroblasts,,Microcalorimetry as a tool for Cr(VI) toxicity evaluation of human dermal fibroblasts Abs: 
1578042,Rouff 2012,The use of TG/DSC–FT-IR to assess the effect of Cr sorption on struvite stability and composition,,The use of TG/DSC–FT-IR to assess the effect of Cr sorption on struvite stability and composition Abs: 
1578041,Morales-Barrera and  Cristiani-Urbina 2007,Hexavalent Chromium Removal by a Trichoderma inhamatum Fungal Strain Isolated from Tannery Effluent,,Hexavalent Chromium Removal by a Trichoderma inhamatum Fungal Strain Isolated from Tannery Effluent Abs: 
1578040,Gagneten et al. 2009,"Assessment of Bioconcentration Factor of Chromium by Instrumental Neutron Activation Analysis in Argyrodiaptomus falcifer Daday, a Subtropical Freshwater Copepod",,"Assessment of Bioconcentration Factor of Chromium by Instrumental Neutron Activation Analysis in Argyrodiaptomus falcifer Daday, a Subtropical Freshwater Copepod Abs: "
1578039,Park et al. 2011,Consideration of the methods for evaluating the Cr(VI)-removing capacity of biomaterial,,Consideration of the methods for evaluating the Cr(VI)-removing capacity of biomaterial Abs: 
1578038,Tomachuk et al. 2010,Morphology and corrosion resistance of Cr(III)-based conversion treatments for electrogalvanized steel,,Morphology and corrosion resistance of Cr(III)-based conversion treatments for electrogalvanized steel Abs: 
1578037,Sankaran et al. 2010,"Geophysical and tracer studies to detect subsurface chromium contamination and suitable site for waste disposal in Ranipet, Vellore district, Tamil Nadu, India",,"Geophysical and tracer studies to detect subsurface chromium contamination and suitable site for waste disposal in Ranipet, Vellore district, Tamil Nadu, India Abs: "
1578036,Sicilia et al. 1993,Micellar effects on reaction kinetics,,Micellar effects on reaction kinetics Abs: 
1578035,Sicilia et al. 1994,Micellar effects on reaction kinetics,,Micellar effects on reaction kinetics Abs: 
1578034,Wampler et al. 1996,Composites of polypyrrole and carbon black: 4. Use in environmental pollution abatement of hexavalent chromium,,Composites of polypyrrole and carbon black: 4. Use in environmental pollution abatement of hexavalent chromium Abs: 
1578027,Frías et al. 1994,Contribution of toxic elements: Hexavalent chromium in materials used in the manufacture of cement,,Contribution of toxic elements: Hexavalent chromium in materials used in the manufacture of cement Abs: 
1578026,Gokcay and  Yetis 1991,Effect of chromium(VI) on activated sludge,,Effect of chromium(VI) on activated sludge Abs: 
1578025,Nivas et al. 1996,Surfactant enhanced remediation of subsurface chromium contamination,,Surfactant enhanced remediation of subsurface chromium contamination Abs: 
1578023,Persoone et al. 1994,Cyst-based toxicity tests X: comparison of the sensitivity of the acute Daphnia magna test and two crustacean microbiotests for chemicals and wastes,,Cyst-based toxicity tests X: comparison of the sensitivity of the acute Daphnia magna test and two crustacean microbiotests for chemicals and wastes Abs: 
1578021,Panigrahi and  Mishra 1993,Micellar-catalysis: Effect of sodium lauryl sulphate in the oxidation of lactic acid by chromic acid,,Micellar-catalysis: Effect of sodium lauryl sulphate in the oxidation of lactic acid by chromic acid Abs: 
1578019,Peterson et al. 1996,Direct XAFS evidence for heterogeneous redox reaction at the aqueous chromium/magnetite interface,,Direct XAFS evidence for heterogeneous redox reaction at the aqueous chromium/magnetite interface Abs: 
1578016,Orero iserte et al. 2004,Simultaneous determination of arsenic and selenium species in phosphoric acid extracts of sediment samples by HPLC-ICP-MS,,Simultaneous determination of arsenic and selenium species in phosphoric acid extracts of sediment samples by HPLC-ICP-MS Abs: 
1578014,Nan and  Yan 2005,On-line dynamic two-dimensional admicelles solvent extraction coupled to electrothermal atomic absorption spectrometry for determination of chromium(VI) in drinking water,,On-line dynamic two-dimensional admicelles solvent extraction coupled to electrothermal atomic absorption spectrometry for determination of chromium(VI) in drinking water Abs: 
1578011,Wu et al. 2007,The adsorption and catalytic transformations of chromium on Mn substituted goethite,,The adsorption and catalytic transformations of chromium on Mn substituted goethite Abs: 
1578010,Omole et al. 2007,Palladium nanoparticles for catalytic reduction of Cr(VI) using formic acid,,Palladium nanoparticles for catalytic reduction of Cr(VI) using formic acid Abs: 
1578009,Lin et al. 2009,Photo-enhancement of Cr(VI) reduction by fungal biomass of Neurospora crassa,,Photo-enhancement of Cr(VI) reduction by fungal biomass of Neurospora crassa Abs: 
1578008,Zhang et al. 2009,Electrocatalytic reduction of chromium by poly(aniline-co-o-aminophenol): An efficient and recyclable way to remove Cr(VI) in wastewater,,Electrocatalytic reduction of chromium by poly(aniline-co-o-aminophenol): An efficient and recyclable way to remove Cr(VI) in wastewater Abs: 
1578007,Xu et al. 2011,Characteristics of amine-crosslinked wheat straw and its adsorption mechanisms for phosphate and chromium (VI) removal from aqueous solution,,Characteristics of amine-crosslinked wheat straw and its adsorption mechanisms for phosphate and chromium (VI) removal from aqueous solution Abs: 
1578006,Yu et al. 2005,The leachability of heavy metals in hardened fly ash cement and cement-solidified fly ash,,The leachability of heavy metals in hardened fly ash cement and cement-solidified fly ash Abs: 
1578004,Wise et al. 2009,A global assessment of chromium pollution using sperm whales (Physeter macrocephalus) as an indicator species,"Chromium (Cr) is a well-known human carcinogen and a potential reproductive toxicant, but its contribution to ocean pollution is poorly understood. The aim of this study was to provide a global baseline for Cr as a marine pollutant using the sperm whale (Physeter macrocephalus) as an indicator species. Biopsies were collected from free-ranging whales around the globe during the voyage of the research vessel The Odyssey. Total Cr levels were measured in 361 sperm whales collected from 16 regions around the globe detectable levels ranged from 0.9 to 122.6 microg Cr g tissue(-1) with a global mean of 8.8+/-0.9 microg g(-1). Two whales had undetectable levels. The highest levels were found in sperm whales sampled in the waters near the Islands of Kiribati in the Pacific (mean=44.3+/-14.4) and the Seychelles in the Indian Ocean (mean=19.5+/-5.4 microg g(-1)). The lowest mean levels were found in whales near the Canary Islands (mean=3.7+/-0.8 microg g(-1)) and off of the coast of Sri Lanka (mean=3.3+/-0.4 microg g(-1)). The global mean Cr level in whale skin was 28-times higher than mean Cr skin levels in humans without occupational exposure. The whale levels were more similar to levels only observed previously in human lung tissue from workers who died of Cr-induced lung cancer. We conclude that Cr pollution in the marine environment is significant and that further study is urgently needed.","A global assessment of chromium pollution using sperm whales (Physeter macrocephalus) as an indicator species Abs: Chromium (Cr) is a well-known human carcinogen and a potential reproductive toxicant, but its contribution to ocean pollution is poorly understood. The aim of this study was to provide a global baseline for Cr as a marine pollutant using the sperm whale (Physeter macrocephalus) as an indicator species. Biopsies were collected from free-ranging whales around the globe during the voyage of the research vessel The Odyssey. Total Cr levels were measured in 361 sperm whales collected from 16 regions around the globe detectable levels ranged from 0.9 to 122.6 microg Cr g tissue(-1) with a global mean of 8.8+/-0.9 microg g(-1). Two whales had undetectable levels. The highest levels were found in sperm whales sampled in the waters near the Islands of Kiribati in the Pacific (mean=44.3+/-14.4) and the Seychelles in the Indian Ocean (mean=19.5+/-5.4 microg g(-1)). The lowest mean levels were found in whales near the Canary Islands (mean=3.7+/-0.8 microg g(-1)) and off of the coast of Sri Lanka (mean=3.3+/-0.4 microg g(-1)). The global mean Cr level in whale skin was 28-times higher than mean Cr skin levels in humans without occupational exposure. The whale levels were more similar to levels only observed previously in human lung tissue from workers who died of Cr-induced lung cancer. We conclude that Cr pollution in the marine environment is significant and that further study is urgently needed."
1578003,Jo et al. 2010,Combined effects of water quality parameters on mixture toxicity of copper and chromium toward Daphnia magna,"In this study, a central composite design (CCD) was employed to evaluate the combined effects of pH, hardness and dissolved organic carbon (DOC) on the toxicity of a mixture of Cu(II) and Cr(VI) toward Daphnia magna. Overall, the results showed that increases in pH, hardness and DOC concentration led to decreased mixture toxicity of Cu(II) and Cr(VI) by reducing the concentrations of toxic species such as Cu(2+) and HCrO(4)(-). In addition, empirical models for the prediction of 24-h and 48-h mortalities of D. magna were developed and validated by using three different sources of dissolved organic matter (DOM). Because the DOMs had different Cu(II)-binding capacities, the empirical models were revised using the ligand concentration of DOMs instead of the DOC concentration; however, the prediction capability of these models did not differ significantly. These results suggest that it is not likely that the chemical property of DOM is important for prediction of the mixture toxicity of Cu(II) and Cr(VI) toward D. magna when the ligand concentration of DOMs greatly exceed the Cu(II) concentration.","Combined effects of water quality parameters on mixture toxicity of copper and chromium toward Daphnia magna Abs: In this study, a central composite design (CCD) was employed to evaluate the combined effects of pH, hardness and dissolved organic carbon (DOC) on the toxicity of a mixture of Cu(II) and Cr(VI) toward Daphnia magna. Overall, the results showed that increases in pH, hardness and DOC concentration led to decreased mixture toxicity of Cu(II) and Cr(VI) by reducing the concentrations of toxic species such as Cu(2+) and HCrO(4)(-). In addition, empirical models for the prediction of 24-h and 48-h mortalities of D. magna were developed and validated by using three different sources of dissolved organic matter (DOM). Because the DOMs had different Cu(II)-binding capacities, the empirical models were revised using the ligand concentration of DOMs instead of the DOC concentration; however, the prediction capability of these models did not differ significantly. These results suggest that it is not likely that the chemical property of DOM is important for prediction of the mixture toxicity of Cu(II) and Cr(VI) toward D. magna when the ligand concentration of DOMs greatly exceed the Cu(II) concentration."
1578000,Jain and  Garg 2008,"Effect of Cr(VI) on the hydration behavior of marble dust blended cement: Solidification, leachability and XRD analyses",,"Effect of Cr(VI) on the hydration behavior of marble dust blended cement: Solidification, leachability and XRD analyses Abs: "
1577999,Sadaoui et al. 2009,Removal of hexavalent chromium from aqueous solutions by micellar compounds,,Removal of hexavalent chromium from aqueous solutions by micellar compounds Abs: 
1577998,Kassem 2010,Kinetics and thermodynamic treatments of the reduction of hexavalent to trivalent chromium in presence of organic sulphide compounds,,Kinetics and thermodynamic treatments of the reduction of hexavalent to trivalent chromium in presence of organic sulphide compounds Abs: 
1577997,Nosrati et al. 2011,Extraction performance of chromium (VI) with emulsion liquid membrane by Cyanex 923 as carrier using response surface methodology,,Extraction performance of chromium (VI) with emulsion liquid membrane by Cyanex 923 as carrier using response surface methodology Abs: 
1577996,Omraei et al. 2011,Study of the removal of Zn(II) from aqueous solution using polypyrrole nanocomposite,,Study of the removal of Zn(II) from aqueous solution using polypyrrole nanocomposite Abs: 
1577995,Rosales et al. 2012,Application of zeolite-Arthrobacter viscosus system for the removal of heavy metal and dye: Chromium and Azure B,,Application of zeolite-Arthrobacter viscosus system for the removal of heavy metal and dye: Chromium and Azure B Abs: 
1577994,Guo et al. 2011,"Synthesis, characterization and biological evaluation of some 16?-azolyl-3?-amino-5?-androstane derivatives as potential anticancer agents","A series of new 16?-azolyl-3?-amino-5?-androstane derivatives were synthesized and characterized. The new compounds were screened for their anticancer activity against the human cancer cell lines SW480, A549, HepG2, HeLa and SiHa in vitro using the MTT assay. The results of the in vitro study showed that a number of compounds have shown IC(50) values lower than 20 ?M against the five cancer cell lines.","Synthesis, characterization and biological evaluation of some 16?-azolyl-3?-amino-5?-androstane derivatives as potential anticancer agents Abs: A series of new 16?-azolyl-3?-amino-5?-androstane derivatives were synthesized and characterized. The new compounds were screened for their anticancer activity against the human cancer cell lines SW480, A549, HepG2, HeLa and SiHa in vitro using the MTT assay. The results of the in vitro study showed that a number of compounds have shown IC(50) values lower than 20 ?M against the five cancer cell lines."
1577993,Kovacs et al. 2007,Investigation of chromium content in foodstuffs and nutrition supplements by GFAAS and determination of changing Cr(III) to Cr(VI) during baking and toasting bread,,Investigation of chromium content in foodstuffs and nutrition supplements by GFAAS and determination of changing Cr(III) to Cr(VI) during baking and toasting bread Abs: 
1577992,Shah et al. 2008,"Speciation of As, Cr, Se and Hg under coal fired power station conditions",,"Speciation of As, Cr, Se and Hg under coal fired power station conditions Abs: "
1577991,Shah et al. 2012,Speciation of chromium in Australian coals and combustion products,,Speciation of chromium in Australian coals and combustion products Abs: 
1577990,Martorell et al. 2012,Cr(VI) reduction by cell-free extracts of Pichia jadinii and Pichia anomala isolated from textile-dye factory effluents,,Cr(VI) reduction by cell-free extracts of Pichia jadinii and Pichia anomala isolated from textile-dye factory effluents Abs: 
1577989,Pandey and  Upadhyay 2005,Effect of cationic micellar aggregates on the kinetics of oxidation of aminoalcohols by N-bromosuccinimide in alkaline medium,"The kinetics of oxidation of some aminoalcohols (AA), viz. ethanolamine, diethanolamine, and triethanolamine, by N-bromosuccinimide (NBS) in alkaline medium has been investigated in the absence as well as in the presence of cetyltrimethylammonium bromide (CTAB), a cationic surfactant. The reaction always followed a first-order dependence of rate on NBS, while the order in each AA and alkali was found to decrease from unity to zero at higher [AA] and [OH-], respectively. The reaction is strongly catalyzed by CTAB even before the critical micelle concentration (CMC) of CTAB. However, the observed rate constants attained constancy at higher [CTAB] (&gt;CMC of CTAB). The premicellar kinetics has been rationalized in the light of the Piszkiewicz positive cooperativity model [J. Am. Chem. Soc. 99 (1977) 1550]. The binding constants between the reactants and the surfactant have also been evaluated using the Raghvan and Srinivasan model [Proc. Ind. Acad. Sci. 98 (1987) 199], which is applicable to bimolecular micellar catalyzed reaction and predicts constancy in the observed rate constant at higher [surfactant]. The binding constants obtained by both the models are in good agreement.","Effect of cationic micellar aggregates on the kinetics of oxidation of aminoalcohols by N-bromosuccinimide in alkaline medium Abs: The kinetics of oxidation of some aminoalcohols (AA), viz. ethanolamine, diethanolamine, and triethanolamine, by N-bromosuccinimide (NBS) in alkaline medium has been investigated in the absence as well as in the presence of cetyltrimethylammonium bromide (CTAB), a cationic surfactant. The reaction always followed a first-order dependence of rate on NBS, while the order in each AA and alkali was found to decrease from unity to zero at higher [AA] and [OH-], respectively. The reaction is strongly catalyzed by CTAB even before the critical micelle concentration (CMC) of CTAB. However, the observed rate constants attained constancy at higher [CTAB] (&gt;CMC of CTAB). The premicellar kinetics has been rationalized in the light of the Piszkiewicz positive cooperativity model [J. Am. Chem. Soc. 99 (1977) 1550]. The binding constants between the reactants and the surfactant have also been evaluated using the Raghvan and Srinivasan model [Proc. Ind. Acad. Sci. 98 (1987) 199], which is applicable to bimolecular micellar catalyzed reaction and predicts constancy in the observed rate constant at higher [surfactant]. The binding constants obtained by both the models are in good agreement."
1577988,Park et al. 2008,XAS and XPS studies on chromium-binding groups of biomaterial during Cr(VI) biosorption,"The reduction of toxic Cr(VI) to the less or nontoxic Cr(III) may be an useful detoxification technique for the treatment of Cr(VI)-contaminated waters. Recently, the protonated biomass of brown seaweed, Ecklonia, was shown to completely reduce Cr(VI) to Cr(III) in the pH range 1-5. The reduction of Cr(VI) to Cr(III) appeared to occur at the surface of the biomass. In this study, abiotic Cr(VI) reduction by the biomass was performed with various contact times, pHs and initial Cr(VI) concentrations, and surface and bulk characteristics of the Cr-laden biomass was then investigated using X-ray photoelectron spectroscopy (XPS) and X-ray absorption spectroscopy (XAS). The XPS spectra indicated that the Cr(VI) bound to the biomass was completely reduced to Cr(III) at tested various conditions. XANES and EXAFS spectra of the Cr-laden biomass were very similar to those of Cr(III)-acetate, which means that the Cr bound to the biomass during Cr(VI) reduction had an octahedral geometrical arrangement. The bonding distance of the chromium oxygen atoms was approximately 1.97-1.99 A. In conclusion, it was obvious that oxygen containing groups, such as carboxyl and phenolic groups, play a major role in the binding of the Cr(III) resulting from the abiotic reduction of Cr(VI) by the biomass.","XAS and XPS studies on chromium-binding groups of biomaterial during Cr(VI) biosorption Abs: The reduction of toxic Cr(VI) to the less or nontoxic Cr(III) may be an useful detoxification technique for the treatment of Cr(VI)-contaminated waters. Recently, the protonated biomass of brown seaweed, Ecklonia, was shown to completely reduce Cr(VI) to Cr(III) in the pH range 1-5. The reduction of Cr(VI) to Cr(III) appeared to occur at the surface of the biomass. In this study, abiotic Cr(VI) reduction by the biomass was performed with various contact times, pHs and initial Cr(VI) concentrations, and surface and bulk characteristics of the Cr-laden biomass was then investigated using X-ray photoelectron spectroscopy (XPS) and X-ray absorption spectroscopy (XAS). The XPS spectra indicated that the Cr(VI) bound to the biomass was completely reduced to Cr(III) at tested various conditions. XANES and EXAFS spectra of the Cr-laden biomass were very similar to those of Cr(III)-acetate, which means that the Cr bound to the biomass during Cr(VI) reduction had an octahedral geometrical arrangement. The bonding distance of the chromium oxygen atoms was approximately 1.97-1.99 A. In conclusion, it was obvious that oxygen containing groups, such as carboxyl and phenolic groups, play a major role in the binding of the Cr(III) resulting from the abiotic reduction of Cr(VI) by the biomass."
1577987,Yilmaz and  Somer 2009,"Investigation of polarographic interference between Se(IV) and Cr(VI), its elimination and application to Gerede river water",,"Investigation of polarographic interference between Se(IV) and Cr(VI), its elimination and application to Gerede river water Abs: "
1577986,Wang and  Xu 2005,Reduction of Cr(VI) by hydrazine in solution saturated with KHCO3,"Cr(VI) that exists in many industrial wastes is considered highly toxic. One of the most common ways to dispose of these wastes is to reduce Cr(VI) to Cr(III), which is less toxic and can be easily removed or fixed. Reduction of Cr(VI) by hydrazine in aqueous solutions saturated with potassium bicarbonate was studied in this paper. The content of Cr(VI), molar ratio of hydrazine to Cr(VI) and reaction temperature were 200-1000 ppm, 2:1-10:1 and 25-70 degrees C, respectively. Results showed that the overall reaction was third-order, i.e. first-order with respect to hydrazine and second-order with respect to Cr(VI). The apparent empirical activation energy was 75.6 kJmol(-1). The reaction kinetics could be interpreted by a three-step mechanism. Effect of the oxygen in the solution on the reduction of Cr(VI) was negligible.","Reduction of Cr(VI) by hydrazine in solution saturated with KHCO3 Abs: Cr(VI) that exists in many industrial wastes is considered highly toxic. One of the most common ways to dispose of these wastes is to reduce Cr(VI) to Cr(III), which is less toxic and can be easily removed or fixed. Reduction of Cr(VI) by hydrazine in aqueous solutions saturated with potassium bicarbonate was studied in this paper. The content of Cr(VI), molar ratio of hydrazine to Cr(VI) and reaction temperature were 200-1000 ppm, 2:1-10:1 and 25-70 degrees C, respectively. Results showed that the overall reaction was third-order, i.e. first-order with respect to hydrazine and second-order with respect to Cr(VI). The apparent empirical activation energy was 75.6 kJmol(-1). The reaction kinetics could be interpreted by a three-step mechanism. Effect of the oxygen in the solution on the reduction of Cr(VI) was negligible."
1577985,Pamukoglu and  Kargi 2007,Mathematical modeling of copper(II) ion inhibition on COD removal in an activated sludge unit,"A mathematical model was developed to describe the Cu(II) ion inhibition on chemical oxygen demand (COD) removal from synthetic wastewater containing 15 mg l(-1) Cu(II) in an activated sludge unit. Experimental data obtained at different sludge ages (5-30 days) and hydraulic residence times (HRT) (5-25 h) were used to determine the kinetic, stoichiometric and inhibition constants for the COD removal rate in the presence and absence of Cu(II) ions. The inhibition pattern was identified as non-competitive, since Cu(II) ion inhibitions were observed both on maximum specific substrate removal rate (k) and on the saturation constant (Ks) with the inhibition constants of 97 and 18 mg l(-1), respectively, indicating more pronounced inhibition on Ks. The growth yield coefficient (Y) decreased and the death rate constant (b) increased in the presence of Cu(II) ions due to copper ion toxicity on microbial growth with inhibition constants of 29 and 200 mg l(-1), respectively indicating more effective inhibition on the growth yield coefficient or higher maintenance requirements. The mathematical model with the predetermined kinetic constants was able to predict the system performance reasonably well especially at high HRT operations.","Mathematical modeling of copper(II) ion inhibition on COD removal in an activated sludge unit Abs: A mathematical model was developed to describe the Cu(II) ion inhibition on chemical oxygen demand (COD) removal from synthetic wastewater containing 15 mg l(-1) Cu(II) in an activated sludge unit. Experimental data obtained at different sludge ages (5-30 days) and hydraulic residence times (HRT) (5-25 h) were used to determine the kinetic, stoichiometric and inhibition constants for the COD removal rate in the presence and absence of Cu(II) ions. The inhibition pattern was identified as non-competitive, since Cu(II) ion inhibitions were observed both on maximum specific substrate removal rate (k) and on the saturation constant (Ks) with the inhibition constants of 97 and 18 mg l(-1), respectively, indicating more pronounced inhibition on Ks. The growth yield coefficient (Y) decreased and the death rate constant (b) increased in the presence of Cu(II) ions due to copper ion toxicity on microbial growth with inhibition constants of 29 and 200 mg l(-1), respectively indicating more effective inhibition on the growth yield coefficient or higher maintenance requirements. The mathematical model with the predetermined kinetic constants was able to predict the system performance reasonably well especially at high HRT operations."
1577984,Wang et al. 2007,Bioleaching of chromium from tannery sludge by indigenous Acidithiobacillus thiooxidans,"Chromium in tannery sludge will cause serious environmental problems and is toxic to organisms. The acidophilic sulfur-oxidizing Acidithiobacillus thiooxidans can leach heavy metals form urban and industrial wastes. This study examined the ability of an indigenous sulfur-oxidizing A. thiooxidans to leach chromium from tannery sludge. The results showed that the pH of sludge mixture inoculated with the indigenous A. thiooxidans decreased to around 2.0 after 4 days. After 6 days incubation in shaking flasks at 30 degrees C and 160 rpm, up to 99% of chromium was solubilized from tannery sludge. When treated in a 2-l bubble column bioreactor for 5 days at 30 degrees C and aeration of 0.5 vvm, 99.7% of chromium was leached from tannery sludge. The results demonstrated that chromium in tannery sludge can be efficiently leached by the indigenous A. thiooxidans.","Bioleaching of chromium from tannery sludge by indigenous Acidithiobacillus thiooxidans Abs: Chromium in tannery sludge will cause serious environmental problems and is toxic to organisms. The acidophilic sulfur-oxidizing Acidithiobacillus thiooxidans can leach heavy metals form urban and industrial wastes. This study examined the ability of an indigenous sulfur-oxidizing A. thiooxidans to leach chromium from tannery sludge. The results showed that the pH of sludge mixture inoculated with the indigenous A. thiooxidans decreased to around 2.0 after 4 days. After 6 days incubation in shaking flasks at 30 degrees C and 160 rpm, up to 99% of chromium was solubilized from tannery sludge. When treated in a 2-l bubble column bioreactor for 5 days at 30 degrees C and aeration of 0.5 vvm, 99.7% of chromium was leached from tannery sludge. The results demonstrated that chromium in tannery sludge can be efficiently leached by the indigenous A. thiooxidans."
1577983,Pamukoglu and  Kargi 2007,Elimination of Cu(II) toxicity by powdered waste sludge (PWS) addition to an activated sludge unit treating Cu(II) containing synthetic wastewater,"Copper(II) ion toxicity onto activated sludge organisms was eliminated by addition of powdered waste sludge (PWS) to the feed wastewater for removal of Cu(II) ions by biosorption before biological treatment. The synthetic feed wastewater containing 14 or 22 mgl(-1) Cu(II) was mixed with PWS in a mixing tank where Cu(II) ions were adsorbed onto PWS and the mixture was fed to a sedimentation tank to separate Cu(II) containing PWS from the feed wastewater. The activated sludge unit fed with the effluent of the sedimentation tank was operated at a hydraulic residence time (HRT) of 10h and sludge age (SRT) of 10 days. To investigate Cu(II), COD and toxicity removal performance of the activated sludge unit at different PWS loadings, the system was operated at different PWS loading rates (0.1-1 gPWSh(-1)) while the Cu(II) loading rate was constant throughout the operation. Percent copper, COD and toxicity removals increased with increasing PWS loading rate due to increased adsorption of Cu(II) onto PWS yielding low Cu(II) contents in the feed. Biomass concentration in the aeration tank increased and the sludge volume index (SVI) decreased with increasing PWS loading rate due to elimination of Cu(II) from the feed wastewater by PWS addition. PWS addition to the Cu(II) containing wastewater was proven to be effective for removal of Cu(II) by biosorption before biological treatment. Approximately, 1 gPWSh(-1) should be added for 28 mgCuh(-1) loading rate for complete removal of Cu(II) from the feed wastewater to obtain high COD removals in the activated sludge unit.","Elimination of Cu(II) toxicity by powdered waste sludge (PWS) addition to an activated sludge unit treating Cu(II) containing synthetic wastewater Abs: Copper(II) ion toxicity onto activated sludge organisms was eliminated by addition of powdered waste sludge (PWS) to the feed wastewater for removal of Cu(II) ions by biosorption before biological treatment. The synthetic feed wastewater containing 14 or 22 mgl(-1) Cu(II) was mixed with PWS in a mixing tank where Cu(II) ions were adsorbed onto PWS and the mixture was fed to a sedimentation tank to separate Cu(II) containing PWS from the feed wastewater. The activated sludge unit fed with the effluent of the sedimentation tank was operated at a hydraulic residence time (HRT) of 10h and sludge age (SRT) of 10 days. To investigate Cu(II), COD and toxicity removal performance of the activated sludge unit at different PWS loadings, the system was operated at different PWS loading rates (0.1-1 gPWSh(-1)) while the Cu(II) loading rate was constant throughout the operation. Percent copper, COD and toxicity removals increased with increasing PWS loading rate due to increased adsorption of Cu(II) onto PWS yielding low Cu(II) contents in the feed. Biomass concentration in the aeration tank increased and the sludge volume index (SVI) decreased with increasing PWS loading rate due to elimination of Cu(II) from the feed wastewater by PWS addition. PWS addition to the Cu(II) containing wastewater was proven to be effective for removal of Cu(II) by biosorption before biological treatment. Approximately, 1 gPWSh(-1) should be added for 28 mgCuh(-1) loading rate for complete removal of Cu(II) from the feed wastewater to obtain high COD removals in the activated sludge unit."
1577982,Moon et al. 2009,Evaluation of the treatment of chromite ore processing residue by ferrous sulfate and asphalt,"The effectiveness of the treatment of chromite ore processing residue (COPR) with ferrous sulfate and encapsulation into asphalt were explored separately and in combination. The asphalt treatment was conducted by mixing COPR or ferrous sulfate pretreated COPR with varying amounts of asphalt. To assess the efficacy of the treatment, the leachability of toxicity characteristic leaching procedure (TCLP) total chromium (Cr) from all treated samples was determined for curing periods up to 16 months. X-ray absorption near edge structure (XANES) analyses were also performed to evaluate the Cr(6+) concentration in the selected samples. The combination treatment of ferrous sulfate and the encapsulation of the treated COPR into asphalt reduced the TCLP total Cr concentration to lower than the regulatory limit of 5mg/L for Cr contaminated soils, after 16 months. However, the Cr concentrations were still higher than the universal treatment standards (UTS) of 0.6 mg/L for hazardous waste. On the other hand, treatment with ferrous sulfate alone or the encapsulation of the COPR in asphalt failed to meet the TCLP total Cr concentration of 5mg/L, after 16 months. XANES analyses results showed that more than 75% Cr(6+) reduction was achieved upon pretreatment with ferrous sulfate.","Evaluation of the treatment of chromite ore processing residue by ferrous sulfate and asphalt Abs: The effectiveness of the treatment of chromite ore processing residue (COPR) with ferrous sulfate and encapsulation into asphalt were explored separately and in combination. The asphalt treatment was conducted by mixing COPR or ferrous sulfate pretreated COPR with varying amounts of asphalt. To assess the efficacy of the treatment, the leachability of toxicity characteristic leaching procedure (TCLP) total chromium (Cr) from all treated samples was determined for curing periods up to 16 months. X-ray absorption near edge structure (XANES) analyses were also performed to evaluate the Cr(6+) concentration in the selected samples. The combination treatment of ferrous sulfate and the encapsulation of the treated COPR into asphalt reduced the TCLP total Cr concentration to lower than the regulatory limit of 5mg/L for Cr contaminated soils, after 16 months. However, the Cr concentrations were still higher than the universal treatment standards (UTS) of 0.6 mg/L for hazardous waste. On the other hand, treatment with ferrous sulfate alone or the encapsulation of the COPR in asphalt failed to meet the TCLP total Cr concentration of 5mg/L, after 16 months. XANES analyses results showed that more than 75% Cr(6+) reduction was achieved upon pretreatment with ferrous sulfate."
1577981,Vinod et al. 2010,Biosorption of nickel and total chromium from aqueous solution by gum kondagogu (Cochlospermum gossypium): A carbohydrate biopolymer,"Gum kondagogu (Cochlospermum gossypium), an exudates tree gum from India was explored for its potential to decontaminate toxic metal ions in aqueous solution. The toxic metal ions nickel and total chromium biosorption capacity of the gum kondagogu were studied in the batch experimental mode. The optimum conditions of biosorption were determined by investigating pH, contact time, and initial metal ion and biosorbent concentrations. The Freundlich and Langmuir adsorption models were used for the mathematical description of biosorption equilibrium and the data were analyzed on the basis of pseudo-second-order kinetic model. The maximum biosorption capacity of gum kondagogu as calculated by Langmuir model were found to be 50.5 mg g(-1) for nickel at pH 5.0+/-0.1 and 129.8 mg g(-1) for total chromium at pH 2.0+/-0.1, respectively. FTIR, SEM-EDXA and XPS analysis were used to evaluate the binding characteristics of gum kondagogu with metals. The experimental results demonstrate that the metal-ion interaction occurs through ion-exchange, adsorption and precipitation mechanisms.","Biosorption of nickel and total chromium from aqueous solution by gum kondagogu (Cochlospermum gossypium): A carbohydrate biopolymer Abs: Gum kondagogu (Cochlospermum gossypium), an exudates tree gum from India was explored for its potential to decontaminate toxic metal ions in aqueous solution. The toxic metal ions nickel and total chromium biosorption capacity of the gum kondagogu were studied in the batch experimental mode. The optimum conditions of biosorption were determined by investigating pH, contact time, and initial metal ion and biosorbent concentrations. The Freundlich and Langmuir adsorption models were used for the mathematical description of biosorption equilibrium and the data were analyzed on the basis of pseudo-second-order kinetic model. The maximum biosorption capacity of gum kondagogu as calculated by Langmuir model were found to be 50.5 mg g(-1) for nickel at pH 5.0+/-0.1 and 129.8 mg g(-1) for total chromium at pH 2.0+/-0.1, respectively. FTIR, SEM-EDXA and XPS analysis were used to evaluate the binding characteristics of gum kondagogu with metals. The experimental results demonstrate that the metal-ion interaction occurs through ion-exchange, adsorption and precipitation mechanisms."
1577980,Wu et al. 2011,Preparation of ceramic-corrosion-cell fillers and application for cyclohexanone industry wastewater treatment in electrobath reactor,"As new media, ceramic-corrosion-cell fillers (Cathode Ceramic-corrosion-cell Fillers - CCF, and Anode Ceramic-corrosion-cell Fillers - ACF) employed in electrobath were investigated for cyclohexanone industry wastewater treatment. 60.0 wt% of dried sewage sludge and 40.0 wt% of clay, 40.0 wt% of scrap iron and 60.0 wt% of clay were utilized as raw materials for the preparation of raw CCF and ACF, respectively. The raw CCF and ACF were respectively sintered at 400°C for 20 min in anoxic conditions. The physical properties (bulk density, grain density and water absorption), structural and morphological characters and toxic metal leaching contents were tested. The influences of pH, hydraulic retention time (HRT) and the media height on removal of COD(Cr) and cyclohexanone were studied. The results showed that the bulk density and grain density of CCF and ACF were 869.0 kg m(-3) and 936.3 kg m(-3), 1245.0 kg m(-3) and 1420.0 kg m(-3), respectively. The contents of toxic metal (Cu, Zn, Cd, Pb, Cr, Ba, Ni and As) were all below the detection limit. When pH of 3-4, HRT of 6h and the media height of 60 cm were applied, about 90% of COD(cr) and cyclohexanone were removed.","Preparation of ceramic-corrosion-cell fillers and application for cyclohexanone industry wastewater treatment in electrobath reactor Abs: As new media, ceramic-corrosion-cell fillers (Cathode Ceramic-corrosion-cell Fillers - CCF, and Anode Ceramic-corrosion-cell Fillers - ACF) employed in electrobath were investigated for cyclohexanone industry wastewater treatment. 60.0 wt% of dried sewage sludge and 40.0 wt% of clay, 40.0 wt% of scrap iron and 60.0 wt% of clay were utilized as raw materials for the preparation of raw CCF and ACF, respectively. The raw CCF and ACF were respectively sintered at 400°C for 20 min in anoxic conditions. The physical properties (bulk density, grain density and water absorption), structural and morphological characters and toxic metal leaching contents were tested. The influences of pH, hydraulic retention time (HRT) and the media height on removal of COD(Cr) and cyclohexanone were studied. The results showed that the bulk density and grain density of CCF and ACF were 869.0 kg m(-3) and 936.3 kg m(-3), 1245.0 kg m(-3) and 1420.0 kg m(-3), respectively. The contents of toxic metal (Cu, Zn, Cd, Pb, Cr, Ba, Ni and As) were all below the detection limit. When pH of 3-4, HRT of 6h and the media height of 60 cm were applied, about 90% of COD(cr) and cyclohexanone were removed."
1577979,Park et al. 2009,"Combined effects of pH, hardness and dissolved organic carbon on acute metal toxicity to Daphnia magna",,"Combined effects of pH, hardness and dissolved organic carbon on acute metal toxicity to Daphnia magna Abs: "
1577978,Idris et al. 2012,Photocatalytic reduction of Cr(VI) by PVA-alginate encapsulated ?Fe2O3 magnetic beads using different types of illumination lamp and light,,Photocatalytic reduction of Cr(VI) by PVA-alginate encapsulated ?Fe2O3 magnetic beads using different types of illumination lamp and light Abs: 
1577977,Zhang et al. 2012,Simultaneous reduction of vanadium (V) and chromium (VI) with enhanced energy recovery based on microbial fuel cell technology,,Simultaneous reduction of vanadium (V) and chromium (VI) with enhanced energy recovery based on microbial fuel cell technology Abs: 
1577976,Palaniappan and  Chandra shekhar 2004,Synthesis of 7-hydroxy-4-methyl coumarin using polyaniline supported acid catalyst,,Synthesis of 7-hydroxy-4-methyl coumarin using polyaniline supported acid catalyst Abs: 
1577975,Islam et al. 2005,"Kinetics and mechanism of 2,2?-bipyridyl and 1,10-phenanthroline-catalysed chromium(VI) oxidation of d-fructose in aqueous micellar media",,"Kinetics and mechanism of 2,2?-bipyridyl and 1,10-phenanthroline-catalysed chromium(VI) oxidation of d-fructose in aqueous micellar media Abs: "
1577974,Islam et al. 2007,Kinetics and mechanism of picolinic acid promoted chromic acid oxidation of maleic acid in aqueous micellar media,,Kinetics and mechanism of picolinic acid promoted chromic acid oxidation of maleic acid in aqueous micellar media Abs: 
1577973,Shrivastava et al. 2012,Micelle catalyzed oxidative degradation of norfloxacin by chloramine-T,,Micelle catalyzed oxidative degradation of norfloxacin by chloramine-T Abs: 
1577972,Wei et al. 2010,Thermal detoxification and bloating of chromium(VI) with bentonite,,Thermal detoxification and bloating of chromium(VI) with bentonite Abs: 
1577971,Nthumbi et al. 2012,Application of chitosan/polyacrylamide nanofibres for removal of chromate and phosphate in water,,Application of chitosan/polyacrylamide nanofibres for removal of chromate and phosphate in water Abs: 
1577970,Polgári et al. 2011,Iron speciation in human cancer cells by K-edge total reflection X-ray fluorescence–X-ray absorption near edge structure analysis,,Iron speciation in human cancer cells by K-edge total reflection X-ray fluorescence–X-ray absorption near edge structure analysis Abs: 
1577969,Khan et al. 2012,Assessment of health risks with reference to oxidative stress and DNA damage in chromium exposed population,"Trivalent chromium [Cr(III)] is widely used in tanning industrial processes. The population living in tanning industrial area is continuously exposed to Cr(III) which appears to be associated with both acute and chronic health problems. Therefore, the aim of this study was to evaluate the health risk with special reference to oxidative stress parameters (malondialdehyde - MDA, glutathione - GSH, and superoxide dismutase - SOD) and DNA damage in 100 Cr-exposed and 100 unexposed populations. The total blood Cr level, SOD level, MDA level and DNA damage were significantly (p&lt;0.05) higher and GSH level was significantly (p&lt;0.05) lower in exposed group as compared to the unexposed group. The altered oxidative stress parameters and DNA damage were found to be slightly higher in female population of both groups. In simple and multiple correlation analyses (adjusted with potential confounders), blood Cr level showed negative significant correlation with GSH level and positive significant correlation with level of MDA, SOD and DNA damage in both groups. The overall prevalence of morbidity was found to be significantly (p&lt;0.05) higher in the exposed group as compared to the unexposed group. In the exposed group, the prevalence of respiratory illness is highest, followed by diabetes, gastrointestinal tract problems and dermal problems respectively. Our results concluded that the Cr(III) exposed population is at high risk for health hazards and the female population is slightly more susceptible to Cr(III) exposure.","Assessment of health risks with reference to oxidative stress and DNA damage in chromium exposed population Abs: Trivalent chromium [Cr(III)] is widely used in tanning industrial processes. The population living in tanning industrial area is continuously exposed to Cr(III) which appears to be associated with both acute and chronic health problems. Therefore, the aim of this study was to evaluate the health risk with special reference to oxidative stress parameters (malondialdehyde - MDA, glutathione - GSH, and superoxide dismutase - SOD) and DNA damage in 100 Cr-exposed and 100 unexposed populations. The total blood Cr level, SOD level, MDA level and DNA damage were significantly (p&lt;0.05) higher and GSH level was significantly (p&lt;0.05) lower in exposed group as compared to the unexposed group. The altered oxidative stress parameters and DNA damage were found to be slightly higher in female population of both groups. In simple and multiple correlation analyses (adjusted with potential confounders), blood Cr level showed negative significant correlation with GSH level and positive significant correlation with level of MDA, SOD and DNA damage in both groups. The overall prevalence of morbidity was found to be significantly (p&lt;0.05) higher in the exposed group as compared to the unexposed group. In the exposed group, the prevalence of respiratory illness is highest, followed by diabetes, gastrointestinal tract problems and dermal problems respectively. Our results concluded that the Cr(III) exposed population is at high risk for health hazards and the female population is slightly more susceptible to Cr(III) exposure."
1577968,Mohamed et al. 2006,A novel kinetic determination of dissolved chromium species in natural and industrial waste water,"A highly sensitive, selective and simple kinetic method was developed for the determination of dissolved chromium species based on the catalytic effect of Cr(III) and/or Cr(VI) on the oxidation of 2-amino-5-methylphenol (AMP) with H(2)O(2). The fixed time and initial rate variants were used for kinetic spectrophotometric measurements by tracing the oxidized product at 400nm for 10min after starting the reaction. Boric acid and Tween-40 exerted pronounced activating and micellar sensitizing effects on the studied redox reaction, respectively. The optimum reaction conditions were: 3.0mmoll(-1) AMP, 0.45moll(-1) H(2)O(2), 0.50moll(-1) boric acid, 4v/v% Tween-40, 10mmoll(-1) phosphate buffer and pH 6.45+/-0.02 at 35 degrees C. Both Cr(III) and Cr(VI) ions exerted the same catalytic effect on the studied reaction. Linear calibration graphs were obtained for the determination of up to 6.0ngml(-1) Cr with detection limits of 0.054 and 0.10ngml(-1) Cr; following the fixed time and initial rate methods, respectively. The proposed method was successfully applied to the speciation and determination of trace levels of dissolved Cr(III) and Cr(VI) in natural and effluents of industrial waste water. The total dissolved Cr(III) and Cr(VI) species was determined first. In a second run, Cr(VI) was determined alone after precipitation of Cr(III) ions in presence of Al(OH)(3) collector, where Cr(III) is then determined by difference. Moreover, published catalytic-spectrophotometric methods for chromium determination were reviewed.","A novel kinetic determination of dissolved chromium species in natural and industrial waste water Abs: A highly sensitive, selective and simple kinetic method was developed for the determination of dissolved chromium species based on the catalytic effect of Cr(III) and/or Cr(VI) on the oxidation of 2-amino-5-methylphenol (AMP) with H(2)O(2). The fixed time and initial rate variants were used for kinetic spectrophotometric measurements by tracing the oxidized product at 400nm for 10min after starting the reaction. Boric acid and Tween-40 exerted pronounced activating and micellar sensitizing effects on the studied redox reaction, respectively. The optimum reaction conditions were: 3.0mmoll(-1) AMP, 0.45moll(-1) H(2)O(2), 0.50moll(-1) boric acid, 4v/v% Tween-40, 10mmoll(-1) phosphate buffer and pH 6.45+/-0.02 at 35 degrees C. Both Cr(III) and Cr(VI) ions exerted the same catalytic effect on the studied reaction. Linear calibration graphs were obtained for the determination of up to 6.0ngml(-1) Cr with detection limits of 0.054 and 0.10ngml(-1) Cr; following the fixed time and initial rate methods, respectively. The proposed method was successfully applied to the speciation and determination of trace levels of dissolved Cr(III) and Cr(VI) in natural and effluents of industrial waste water. The total dissolved Cr(III) and Cr(VI) species was determined first. In a second run, Cr(VI) was determined alone after precipitation of Cr(III) ions in presence of Al(OH)(3) collector, where Cr(III) is then determined by difference. Moreover, published catalytic-spectrophotometric methods for chromium determination were reviewed."
1577967,Monaselidze et al. 2006,Characterization of chromium-induced apoptosis in cultured mammalian cells,,Characterization of chromium-induced apoptosis in cultured mammalian cells Abs: 
1577966,Ruotolo et al. 2006,Electrochemical treatment of effluents containing Cr(VI). Influence of pH and current on the kinetic,"Compounds of Cr(VI) are very toxic and their reduction to Cr(III) is necessary to allow their further precipitation or adsorption. Chemical methods for Cr(VI) reduction are usually used for this purpose. As an alternative, electrochemical methods using three-dimensional electrodes, such as reticulated vitreous carbon (RVC) and polyaniline-modified RVC, have been used successfully. Since the pH affects reaction of Cr(VI) reduction, in this work its effect on the reaction rate was studied using electrodes of RVC and RVC/PANI. While a maximum in reaction rate was found for a pH 1.5 using the RVC, the RVC/PANI showed no differences in reaction rates in the range of pH between 0 and 1. Practically, no reaction was observed for any pH greater than 3. The effect of different current densities using optimized pH was also evaluated and the RVC/PANI electrode showed the best reaction rates, current efficiencies and energy consumption as a result of the polyaniline electrocatalytic effect.","Electrochemical treatment of effluents containing Cr(VI). Influence of pH and current on the kinetic Abs: Compounds of Cr(VI) are very toxic and their reduction to Cr(III) is necessary to allow their further precipitation or adsorption. Chemical methods for Cr(VI) reduction are usually used for this purpose. As an alternative, electrochemical methods using three-dimensional electrodes, such as reticulated vitreous carbon (RVC) and polyaniline-modified RVC, have been used successfully. Since the pH affects reaction of Cr(VI) reduction, in this work its effect on the reaction rate was studied using electrodes of RVC and RVC/PANI. While a maximum in reaction rate was found for a pH 1.5 using the RVC, the RVC/PANI showed no differences in reaction rates in the range of pH between 0 and 1. Practically, no reaction was observed for any pH greater than 3. The effect of different current densities using optimized pH was also evaluated and the RVC/PANI electrode showed the best reaction rates, current efficiencies and energy consumption as a result of the polyaniline electrocatalytic effect."
1577965,Yalçin and  Apak 2004,"Chromium(III, VI) speciation analysis with preconcentration on a maleic acid-functionalized XAD sorbent",,"Chromium(III, VI) speciation analysis with preconcentration on a maleic acid-functionalized XAD sorbent Abs: "
1577964,Morales et al. 1997,Application of micellar effects to the simultaneous kinetic determination of pyridoxal and pyridoxal-5?-phosphate,,Application of micellar effects to the simultaneous kinetic determination of pyridoxal and pyridoxal-5?-phosphate Abs: 
1577963,Wang and  Vipulanandan 2000,Solidification/stabilization of Cr(VI) with cement,,Solidification/stabilization of Cr(VI) with cement Abs: 
1577962,Gzara and  Dhahbi 2001,Removal of chromate anions by micellar-enhanced ultrafiltration using cationic surfactants,,Removal of chromate anions by micellar-enhanced ultrafiltration using cationic surfactants Abs: 
1577961,Goodgame et al. 1984,Formation of water-soluble chromium(V) by the interaction of humic acid and the carcinogen chromium(VI),,Formation of water-soluble chromium(V) by the interaction of humic acid and the carcinogen chromium(VI) Abs: 
1577960,Sreedhara et al. 1997,"Vanadate and chromate reduction by saccharides and L-ascorbic acid: effect of the isolated V(IV) and Cr(III) products on DNA nicking, lipid peroxidation, cytotoxicity and on enzymatic and non-enzymatic antioxidants",,"Vanadate and chromate reduction by saccharides and L-ascorbic acid: effect of the isolated V(IV) and Cr(III) products on DNA nicking, lipid peroxidation, cytotoxicity and on enzymatic and non-enzymatic antioxidants Abs: "
1577959,Mount 2000,"Use of toxicity identification evaluation methods to characterize, identify, and confirm hexavalent chromium toxicity in an industrial effluent",,"Use of toxicity identification evaluation methods to characterize, identify, and confirm hexavalent chromium toxicity in an industrial effluent Abs: "
1577958,Klein 2000,Age as a factor influencing results in the acute daphnid test with Daphnia magna Straus,,Age as a factor influencing results in the acute daphnid test with Daphnia magna Straus Abs: 
1577957,Pandey et al. 2003,Removal of chromium and reduction of toxicity to Microtox system from tannery effluent by the use of calcium alginate beads containing humic acid,,Removal of chromium and reduction of toxicity to Microtox system from tannery effluent by the use of calcium alginate beads containing humic acid Abs: 
1577956,Qotaibi et al. 1998,Analysis of magnesia chrome refractories weared in a rotary cement kiln,,Analysis of magnesia chrome refractories weared in a rotary cement kiln Abs: 
1577955,Ortega et al. 2003,Combination of synchrotron radiation X-ray microprobe and nuclear microprobe for chromium and chromium oxidation states quantitative mapping in single cells,,Combination of synchrotron radiation X-ray microprobe and nuclear microprobe for chromium and chromium oxidation states quantitative mapping in single cells Abs: 
1577954,Mayes et al. 2000,Multispecies transport of metal–EDTA complexes and chromate through undisturbed columns of weathered fractured saprolite,,Multispecies transport of metal–EDTA complexes and chromate through undisturbed columns of weathered fractured saprolite Abs: 
1577952,O'brien and  Woodbridge 1997,A study of the kinetics of the reduction of chromate by ascorbate under aerobic and anaerobic conditions,,A study of the kinetics of the reduction of chromate by ascorbate under aerobic and anaerobic conditions Abs: 
1577951,Fedrizzi et al. 1996,EIS study of environmentally friendly coil coating performances,,EIS study of environmentally friendly coil coating performances Abs: 
1577949,Zhang 2000,Light and Iron(III)-induced oxidation of chromium(III) in the presence of organic acids and manganese(II) in simulated atmospheric water,,Light and Iron(III)-induced oxidation of chromium(III) in the presence of organic acids and manganese(II) in simulated atmospheric water Abs: 
1577923,Perez-Benito et al. 1998,Catalysis by zinc ion in the reactions of carcinogenic chromium(VI) with thiols,,Catalysis by zinc ion in the reactions of carcinogenic chromium(VI) with thiols Abs: 
1577922,Liu et al. 2012,Synthesis of high saturation magnetization superparamagnetic Fe3O4 hollow microspheres for swift chromium removal,"High saturation magnetization monodisperse Fe(3)O(4) hollow microspheres (109.48 emu/g) with superparamagnetic property at room temperature are promptly synthesized by a one-step solvothermal process with the presence of sodium dodecylbenzenesulfonate as an additive. The as-synthesized products possess superparamagnetism, large cavity, high water solubility, and saturation magnetization at room temperature. In particular, these hollow microspheres exhibit both of a rather short separation time from industry wastewater and a high adsorption capacity about 180 mg/g at high Cr(VI) concentrations, which is much better than those of reported magnetite solid nanoparticles. In addition, the X-ray photoelectron spectra (XPS) show that the uptake of Cr(VI) into the spheres was mainly governed by a physicochemical process. The micelle-assisted Ostwald ripening process was proposed to explain the rapid formation of hollow structures by a series of control experiments. The as-manufactured products with the two advantages mentioned above serve as ideal candidates for environmental remediation materials.","Synthesis of high saturation magnetization superparamagnetic Fe3O4 hollow microspheres for swift chromium removal Abs: High saturation magnetization monodisperse Fe(3)O(4) hollow microspheres (109.48 emu/g) with superparamagnetic property at room temperature are promptly synthesized by a one-step solvothermal process with the presence of sodium dodecylbenzenesulfonate as an additive. The as-synthesized products possess superparamagnetism, large cavity, high water solubility, and saturation magnetization at room temperature. In particular, these hollow microspheres exhibit both of a rather short separation time from industry wastewater and a high adsorption capacity about 180 mg/g at high Cr(VI) concentrations, which is much better than those of reported magnetite solid nanoparticles. In addition, the X-ray photoelectron spectra (XPS) show that the uptake of Cr(VI) into the spheres was mainly governed by a physicochemical process. The micelle-assisted Ostwald ripening process was proposed to explain the rapid formation of hollow structures by a series of control experiments. The as-manufactured products with the two advantages mentioned above serve as ideal candidates for environmental remediation materials."
1577921,Sa?nchez-pastor et al. 2011,Growth of Calcium Carbonate in the Presence of Cr(VI),,Growth of Calcium Carbonate in the Presence of Cr(VI) Abs: 
1577920,Yoshitake et al. 2002,Adsorption of Chromate and Arsenate by Amino-Functionalized MCM-41 and SBA-1,,Adsorption of Chromate and Arsenate by Amino-Functionalized MCM-41 and SBA-1 Abs: 
1577919,Palomar-Rami?rez et al. 2011,Taking Advantage of a Corrosion Problem To Solve a Pollution Problem,,Taking Advantage of a Corrosion Problem To Solve a Pollution Problem Abs: 
1577918,Lu et al. 2006,Removal of Cr(VI) and Cr(III) from Aqueous Solutions and Industrial Wastewaters by Natural Clino-pyrrhotite,,Removal of Cr(VI) and Cr(III) from Aqueous Solutions and Industrial Wastewaters by Natural Clino-pyrrhotite Abs: 
1577917,Stam et al. 2011,Chromium speciation in coal and biomass co-combustion products,"Chromium speciation is vital for the toxicity of products resulting from co-combustion of coal and biomass. Therefore, understanding of formation processes has been studied using a combination of X-ray absorption fine structure (XAFS) spectroscopy and thermodynamic equilibrium calculations. The influence of cofiring on Cr speciation is very dependent on the type of fuel. Cr(VI) contents in the investigated fly ash samples from coal and cofiring average around 7% of the total chromium. An exception is cofiring 7-28% wood for which ashes exhibited Cr(VI) concentrations of 12-16% of the total chromium. Measurements are in line with thermodynamic predictions: RE factors of Cr around 1 are in line with volatile Cr only above 1400 °C; lower Cr(VI) concentrations with lower oxygen content and Cr(III) dissolved in aluminosilicate glass. Stability of Cr(VI) below 700 °C does not correlate with Cr(VI) concentrations found in the combustion products. It is indicated that Cr(VI) formation is a high-temperature process dependent on Cr evaporation (mode of occurrence in fuel, promoted by organic association), oxidation (local oxygen content), and formation of solid chromates (promoted by presence of free lime (CaO) in the ash). CaCrO(4)(s) is a probable chemical form but, given different leachable fractions (varying from 25 to 100%), different forms of Cr(VI) must be present. Clay-bound Cr is likely to dissolve in the aluminosilicate glass phase during melting of the clay.","Chromium speciation in coal and biomass co-combustion products Abs: Chromium speciation is vital for the toxicity of products resulting from co-combustion of coal and biomass. Therefore, understanding of formation processes has been studied using a combination of X-ray absorption fine structure (XAFS) spectroscopy and thermodynamic equilibrium calculations. The influence of cofiring on Cr speciation is very dependent on the type of fuel. Cr(VI) contents in the investigated fly ash samples from coal and cofiring average around 7% of the total chromium. An exception is cofiring 7-28% wood for which ashes exhibited Cr(VI) concentrations of 12-16% of the total chromium. Measurements are in line with thermodynamic predictions: RE factors of Cr around 1 are in line with volatile Cr only above 1400 °C; lower Cr(VI) concentrations with lower oxygen content and Cr(III) dissolved in aluminosilicate glass. Stability of Cr(VI) below 700 °C does not correlate with Cr(VI) concentrations found in the combustion products. It is indicated that Cr(VI) formation is a high-temperature process dependent on Cr evaporation (mode of occurrence in fuel, promoted by organic association), oxidation (local oxygen content), and formation of solid chromates (promoted by presence of free lime (CaO) in the ash). CaCrO(4)(s) is a probable chemical form but, given different leachable fractions (varying from 25 to 100%), different forms of Cr(VI) must be present. Clay-bound Cr is likely to dissolve in the aluminosilicate glass phase during melting of the clay."
1577916,Landrot et al. 2012,Chromium(III) oxidation by three poorly-crystalline manganese(IV) oxides. 1. Chromium(III)-oxidizing capacity,"The Cr(III)-oxidizing capacity of three layered poorly crystalline Mn(IV)O(2) phases, i.e. ?-MnO(2), Random Stacked Birnessite (RSB), and Acid Birnessite (AB), was determined in real-time and in situ, using Quick X-ray Absorption Fine Structure Spectroscopy (Q-XAFS). The results obtained with this technique, which allows the measurement of the total amount of Cr(VI) produced in the system, indicated that the Cr(III) oxidation reaction had ceased between 30 min and 1 h under most experimental conditions. However, this cessation was not observed with a traditional batch technique, which only allows the measurement of Cr(VI) present in solution and thus neglects the amount of Cr(VI) that may be sorbed to Mn(IV)O(2). This study also demonstrated that the Mn(IV)O(2) phase oxidizing the highest amount of Cr(III), which is positively charged in solution, was the mineral featuring the most negatively charged surface. Also, the results indicated that the presence of Mn(II) and/or Mn(III) impurities inside the Mn(IV)O(2) structure could enhance the mineral's capacity to oxidize Cr(III). The information provided in this study will be useful in predicting the capabilities of naturally occurring Mn oxide minerals, which are similar to the three synthetic Mn(IV)O(2) investigated, to oxidize Cr(III) to toxic and mobile Cr(VI) in the soil of contaminated sites.","Chromium(III) oxidation by three poorly-crystalline manganese(IV) oxides. 1. Chromium(III)-oxidizing capacity Abs: The Cr(III)-oxidizing capacity of three layered poorly crystalline Mn(IV)O(2) phases, i.e. ?-MnO(2), Random Stacked Birnessite (RSB), and Acid Birnessite (AB), was determined in real-time and in situ, using Quick X-ray Absorption Fine Structure Spectroscopy (Q-XAFS). The results obtained with this technique, which allows the measurement of the total amount of Cr(VI) produced in the system, indicated that the Cr(III) oxidation reaction had ceased between 30 min and 1 h under most experimental conditions. However, this cessation was not observed with a traditional batch technique, which only allows the measurement of Cr(VI) present in solution and thus neglects the amount of Cr(VI) that may be sorbed to Mn(IV)O(2). This study also demonstrated that the Mn(IV)O(2) phase oxidizing the highest amount of Cr(III), which is positively charged in solution, was the mineral featuring the most negatively charged surface. Also, the results indicated that the presence of Mn(II) and/or Mn(III) impurities inside the Mn(IV)O(2) structure could enhance the mineral's capacity to oxidize Cr(III). The information provided in this study will be useful in predicting the capabilities of naturally occurring Mn oxide minerals, which are similar to the three synthetic Mn(IV)O(2) investigated, to oxidize Cr(III) to toxic and mobile Cr(VI) in the soil of contaminated sites."
1577901,Landrot et al. 2012,Chromium(III) oxidation by three poorly crystalline manganese(IV) oxides. 2. Solid phase analyses,"Layered, poorly crystalline Mn(IV)O(2) phases are abundant in the environment. These mineral phases may rapidly oxidize Cr(III) to more mobile and toxic Cr(VI) in soils. There is still, however, little knowledge of how Cr(III) oxidation by Mn(IV)O(2) proceeds at the microscopic and molecular levels. Therefore, the sorption mechanisms of Cr(III) and Cr(VI) on Random Stacked Birnessite (RSB), ?-MnO(2), and Acid Birnessite (AB) were determined by Extended X-ray Absorption Fine Structure Spectroscopy (EXAFS). These three synthetic Mn(IV)O(2), which are poorly crystalline phases and have layered structures, were reacted with 50 mM Cr(III) at pH 2.5, 3, and 3.5 before being analyzed by EXAFS. The results indicated that Cr(VI) was loosely sorbed as an outer-sphere complex on Mn(IV)O(2), while Cr(III) was tightly sorbed as an inner-sphere complex. Further research is needed to understand why Cr(III) stopped being significantly oxidized by Mn(IV)O(2) after 30 min. This study, however, demonstrated that the formation of a Cr surface precipitate is not necessarily responsible for the cessation in Cr(III) oxidation. Indeed, no Cr surface precipitate was detected at the microscopic and molecular levels on Mn(IV)O(2) surfaces reacted with Cr(III) for 1 h, although the Cr(III) oxidation ceased before 1 h of reaction at most employed experimental conditions.","Chromium(III) oxidation by three poorly crystalline manganese(IV) oxides. 2. Solid phase analyses Abs: Layered, poorly crystalline Mn(IV)O(2) phases are abundant in the environment. These mineral phases may rapidly oxidize Cr(III) to more mobile and toxic Cr(VI) in soils. There is still, however, little knowledge of how Cr(III) oxidation by Mn(IV)O(2) proceeds at the microscopic and molecular levels. Therefore, the sorption mechanisms of Cr(III) and Cr(VI) on Random Stacked Birnessite (RSB), ?-MnO(2), and Acid Birnessite (AB) were determined by Extended X-ray Absorption Fine Structure Spectroscopy (EXAFS). These three synthetic Mn(IV)O(2), which are poorly crystalline phases and have layered structures, were reacted with 50 mM Cr(III) at pH 2.5, 3, and 3.5 before being analyzed by EXAFS. The results indicated that Cr(VI) was loosely sorbed as an outer-sphere complex on Mn(IV)O(2), while Cr(III) was tightly sorbed as an inner-sphere complex. Further research is needed to understand why Cr(III) stopped being significantly oxidized by Mn(IV)O(2) after 30 min. This study, however, demonstrated that the formation of a Cr surface precipitate is not necessarily responsible for the cessation in Cr(III) oxidation. Indeed, no Cr surface precipitate was detected at the microscopic and molecular levels on Mn(IV)O(2) surfaces reacted with Cr(III) for 1 h, although the Cr(III) oxidation ceased before 1 h of reaction at most employed experimental conditions."
1577900,Hsu et al. 2009,Reduction of Cr(VI) by crop-residue-derived black carbon,"Burning crop residues is a common postharvest practice on farmland, leading to the accumulation of black carbon (BC) in the soil. To understand the potential role of BC in immobilizing toxic Cr(VI) in soil, this study evaluated the Cr(VI) sorption kinetics at pH levels ranging from 3 to 7 and examined the reaction mechanism of Cr(VI) with BC derived from burning rice straw. The BC samples, after reacting with Cr(VI), were analyzed using Cr K-edge X-ray absorption spectroscopy. The results showed that Cr(VI) was sorbed and subsequently reduced to Cr(III), which was bound to the BC surface through surface complexation and precipitation. As indicated by the diffuse reflection infrared Fourier transform spectra, the phenolic groups of BC are the dominant drivers of Cr(VI) reduction, giving rise to carbonyl/carboxyl groups on the BC surface. The reaction rate of Cr(VI) with BC increased from 10(-3.62) to 10(-1.65) h(-1) as pH was decreased from 7 to 3 because Cr(VI) sorption and reduction both occur faster at low pH. These results suggest that BC derived from burning crop residue is an effective reductant for Cr(VI) and may play an important role in determining the fate of Cr(VI) in BC-rich farmland soils.","Reduction of Cr(VI) by crop-residue-derived black carbon Abs: Burning crop residues is a common postharvest practice on farmland, leading to the accumulation of black carbon (BC) in the soil. To understand the potential role of BC in immobilizing toxic Cr(VI) in soil, this study evaluated the Cr(VI) sorption kinetics at pH levels ranging from 3 to 7 and examined the reaction mechanism of Cr(VI) with BC derived from burning rice straw. The BC samples, after reacting with Cr(VI), were analyzed using Cr K-edge X-ray absorption spectroscopy. The results showed that Cr(VI) was sorbed and subsequently reduced to Cr(III), which was bound to the BC surface through surface complexation and precipitation. As indicated by the diffuse reflection infrared Fourier transform spectra, the phenolic groups of BC are the dominant drivers of Cr(VI) reduction, giving rise to carbonyl/carboxyl groups on the BC surface. The reaction rate of Cr(VI) with BC increased from 10(-3.62) to 10(-1.65) h(-1) as pH was decreased from 7 to 3 because Cr(VI) sorption and reduction both occur faster at low pH. These results suggest that BC derived from burning crop residue is an effective reductant for Cr(VI) and may play an important role in determining the fate of Cr(VI) in BC-rich farmland soils."
1577899,Fendorf and  Li 1996,Kinetics of Chromate Reduction by Ferrous Iron,,Kinetics of Chromate Reduction by Ferrous Iron Abs: 
1577898,Wittbrodt and  Palmer 1996,"Effect of Temperature, Ionic Strength, Background Electrolytes, and Fe(III) on the Reduction of Hexavalent Chromium by Soil Humic Substances",,"Effect of Temperature, Ionic Strength, Background Electrolytes, and Fe(III) on the Reduction of Hexavalent Chromium by Soil Humic Substances Abs: "
1577897,Patterson et al. 1997,Reduction of Hexavalent Chromium by Amorphous Iron Sulfide,,Reduction of Hexavalent Chromium by Amorphous Iron Sulfide Abs: 
1577896,Rodríguez et al. 2000,The Efficiency of Toxic Chromate Reduction by a Conducting Polymer (Polypyrrole):  Influence of Electropolymerization Conditions,,The Efficiency of Toxic Chromate Reduction by a Conducting Polymer (Polypyrrole):  Influence of Electropolymerization Conditions Abs: 
1577895,Nico and  Zasoski 2000,Importance of Mn(III) Availability on the Rate of Cr(III) Oxidation on ?-MnO 2,,Importance of Mn(III) Availability on the Rate of Cr(III) Oxidation on ?-MnO 2 Abs: 
1577894,Loyaux-Lawniczak et al. 2000,Trapping of Cr by Formation of Ferrihydrite during the Reduction of Chromate Ions by Fe(II)?Fe(III) Hydroxysalt Green Rusts,,Trapping of Cr by Formation of Ferrihydrite during the Reduction of Chromate Ions by Fe(II)?Fe(III) Hydroxysalt Green Rusts Abs: 
1577893,Levina et al. 2004,X-ray absorption spectroscopic studies of chromium(V/IV/III)- 2-ethyl-2-hydroxybutanoato(2-/1-) complexes,"Structures of the complexes [Cr(V)O(ehba)(2)](-), [Cr(IV)O(ehbaH)(2)](0), and [Cr(III)(ehbaH)(2)(OH(2))(2)](+) (ehbaH(2) = 2-ethyl-2-hydroxybutanoic acid) in frozen aqueous solutions (10 K, [Cr] = 10 mM, 1.0 M ehbaH(2)/ehbaH, pH 3.5) have been determined by single- and multiple-scattering fitting of X-ray absorption fine structure (XAFS) data. An optimal set of fitting parameters has been determined from the XAFS calculations for a compound with known crystal structure, Na[Cr(V)O(ehba)(2)] (solid, 10 K). The structure of the Cr(V) complex [Cr(V)O(ehba)(2)](-) does not change in solution in the presence of excess ligand. Contrary to the earlier suggestions made from the kinetic data (Ghosh, M. C.; Gould, E. S. J. Chem. Soc., Chem. Commun. 1992, 195-196), the structure of the Cr(IV) complex (generated by the Cr(VI) + As(III) + ehbaH(2) reaction) is close to that of the Cr(V) complex (five-coordinate, distorted trigonal bipyramidal) and different from that of the Cr(III) complex (six-coordinate, octahedral). For both Cr(V) and Cr(IV) complexes, some disorder in the position of the oxo group is observed, which is consistent with but not definitive for the presence of geometric isomers. The structure of the Cr(IV) complex differs from that of Cr(V) by protonation of alcoholato groups of the ligands, which leads to significant elongation of the corresponding Cr-O bonds (2.0 vs 1.8 A). This is reflected in the different chemical properties reported previously for the Cr(IV) and Cr(V) complexes, including their reactivities toward DNA and other biomolecules in relation to Cr-induced carcinogenicity.","X-ray absorption spectroscopic studies of chromium(V/IV/III)- 2-ethyl-2-hydroxybutanoato(2-/1-) complexes Abs: Structures of the complexes [Cr(V)O(ehba)(2)](-), [Cr(IV)O(ehbaH)(2)](0), and [Cr(III)(ehbaH)(2)(OH(2))(2)](+) (ehbaH(2) = 2-ethyl-2-hydroxybutanoic acid) in frozen aqueous solutions (10 K, [Cr] = 10 mM, 1.0 M ehbaH(2)/ehbaH, pH 3.5) have been determined by single- and multiple-scattering fitting of X-ray absorption fine structure (XAFS) data. An optimal set of fitting parameters has been determined from the XAFS calculations for a compound with known crystal structure, Na[Cr(V)O(ehba)(2)] (solid, 10 K). The structure of the Cr(V) complex [Cr(V)O(ehba)(2)](-) does not change in solution in the presence of excess ligand. Contrary to the earlier suggestions made from the kinetic data (Ghosh, M. C.; Gould, E. S. J. Chem. Soc., Chem. Commun. 1992, 195-196), the structure of the Cr(IV) complex (generated by the Cr(VI) + As(III) + ehbaH(2) reaction) is close to that of the Cr(V) complex (five-coordinate, distorted trigonal bipyramidal) and different from that of the Cr(III) complex (six-coordinate, octahedral). For both Cr(V) and Cr(IV) complexes, some disorder in the position of the oxo group is observed, which is consistent with but not definitive for the presence of geometric isomers. The structure of the Cr(IV) complex differs from that of Cr(V) by protonation of alcoholato groups of the ligands, which leads to significant elongation of the corresponding Cr-O bonds (2.0 vs 1.8 A). This is reflected in the different chemical properties reported previously for the Cr(IV) and Cr(V) complexes, including their reactivities toward DNA and other biomolecules in relation to Cr-induced carcinogenicity."
1577892,Lay and  Levina 1996,Kinetics and Mechanism of Chromium(VI) Reduction to Chromium(III) by -Cysteine in Neutral Aqueous Solutions,,Kinetics and Mechanism of Chromium(VI) Reduction to Chromium(III) by -Cysteine in Neutral Aqueous Solutions Abs: 
1577891,Zhang and  Lay 1998,EPR Spectroscopic Studies on the Formation of Chromium(V) Peroxo Complexes in the Reaction of Chromium(VI) with Hydrogen Peroxide,,EPR Spectroscopic Studies on the Formation of Chromium(V) Peroxo Complexes in the Reaction of Chromium(VI) with Hydrogen Peroxide Abs: 
1577890,Sugden and  Wetterhahn 1996,"Reaction of Chromium(V) with the EPR Spin Traps 5,5-Dimethylpyrroline N -Oxide and Phenyl- N - tert -butylnitrone Resulting in Direct Oxidation",,"Reaction of Chromium(V) with the EPR Spin Traps 5,5-Dimethylpyrroline N -Oxide and Phenyl- N - tert -butylnitrone Resulting in Direct Oxidation Abs: "
1577889,Perez-Benito et al. 1994,"Three Rate Constants from a Single Kinetic Experiment: Formation, Decomposition, and Reactivity of the Chromium(VI)-Glutathione Thioester Intermediate",,"Three Rate Constants from a Single Kinetic Experiment: Formation, Decomposition, and Reactivity of the Chromium(VI)-Glutathione Thioester Intermediate Abs: "
1577888,Rodenas and  Perez-Benito 1991,Chromium(VI) oxidation of alkanol components of sodium dodecyl sulfate reverse micelles,,Chromium(VI) oxidation of alkanol components of sodium dodecyl sulfate reverse micelles Abs: 
1577887,Zhang and  Lay 1996,"EPR Spectroscopic Studies of the Reactions of Cr(VI) with -Ascorbic Acid, -Dehydroascorbic Acid, and 5,6- O -Isopropylidene- -ascorbic Acid in Water. 1 Implications for Chromium(VI) Genotoxicity",,"EPR Spectroscopic Studies of the Reactions of Cr(VI) with -Ascorbic Acid, -Dehydroascorbic Acid, and 5,6- O -Isopropylidene- -ascorbic Acid in Water. 1 Implications for Chromium(VI) Genotoxicity Abs: "
1577886,Levina et al. 2000,"Reactions of Chromium(VI/V/IV) with Bis( O -ethyl- -cysteinato- N, S )zinc(II):  A Model for the Action of Carcinogenic Chromium on Zinc-Finger Proteins 1",,"Reactions of Chromium(VI/V/IV) with Bis( O -ethyl- -cysteinato- N, S )zinc(II):  A Model for the Action of Carcinogenic Chromium on Zinc-Finger Proteins 1 Abs: "
1577885,Lee et al. 2010,Removal Behavior of Surface Modified Sand for Cd(II) and Cr(VI) from Aqueous Solutions,,Removal Behavior of Surface Modified Sand for Cd(II) and Cr(VI) from Aqueous Solutions Abs: 
1577884,Rajesh et al. 2011,Trialkylamine Impregnated Macroporous Polymeric Sorbent for the Effective Removal of Chromium from Industrial Wastewater,,Trialkylamine Impregnated Macroporous Polymeric Sorbent for the Effective Removal of Chromium from Industrial Wastewater Abs: 
1577883,Guo et al. 2011,High-Performance and Reproducible Polyaniline Nanowire/Tubes for Removal of Cr(VI) in Aqueous Solution,,High-Performance and Reproducible Polyaniline Nanowire/Tubes for Removal of Cr(VI) in Aqueous Solution Abs: 
1577882,Idrees et al. 2012,Interaction of Cr 3+ with Silica Gel at the Aqueous Interface Using Fluorescence in Sodium Dodecyl Sulfate Micelles and Confocal Fluorescence Microscopy,,Interaction of Cr 3+ with Silica Gel at the Aqueous Interface Using Fluorescence in Sodium Dodecyl Sulfate Micelles and Confocal Fluorescence Microscopy Abs: 
1577881,Perez-Benito and  Rodenas 1991,Influence of sodium dodecyl sulfate micelles on the oxidation of alcohols by chromic acid,,Influence of sodium dodecyl sulfate micelles on the oxidation of alcohols by chromic acid Abs: 
1577878,Ruotolo and  Gubulin 2003,"Reduction of hexavalent chromium using polyaniline films. Effect of film thickness, potential and flow velocity on the reaction rate and polymer stability",,"Reduction of hexavalent chromium using polyaniline films. Effect of film thickness, potential and flow velocity on the reaction rate and polymer stability Abs: "
1577876,Paleologos et al. 2000,Micelle-mediated methodology for speciation of chromium by flame atomic absorption spectrometry,,Micelle-mediated methodology for speciation of chromium by flame atomic absorption spectrometry Abs: 
1577871,Š?an?ar et al. 2005,"Determination of hexavalent chromium in cement by the use of HPLC-ICP-MS, FPLC-ETAAS, spectrophotometry and selective extraction techniques",,"Determination of hexavalent chromium in cement by the use of HPLC-ICP-MS, FPLC-ETAAS, spectrophotometry and selective extraction techniques Abs: "
1577870,Nagourney et al. 2008,Development of a standard reference material for Cr(vi) in contaminated soil,,Development of a standard reference material for Cr(vi) in contaminated soil Abs: 
1577869,Tan et al. 2011,"Selective detection of nanomolar Cr(vi) in aqueous solution based on 1,4-dithiothreitol functionalized gold nanoparticles",,"Selective detection of nanomolar Cr(vi) in aqueous solution based on 1,4-dithiothreitol functionalized gold nanoparticles Abs: "
1577868,Meeravali et al. 2010,A sensitive sequential non-chromatographic speciation analysis of chromium in natural/wastewaters by inductively coupled plasma optical emission spectrometry,,A sensitive sequential non-chromatographic speciation analysis of chromium in natural/wastewaters by inductively coupled plasma optical emission spectrometry Abs: 
1577867,Sun et al. 2011,Chitosan modified Fe0 nanowires in porous anodic alumina and their application for the removal of hexavalent chromium from water,,Chitosan modified Fe0 nanowires in porous anodic alumina and their application for the removal of hexavalent chromium from water Abs: 
1577866,Ma et al. 2012,Chemical reduction and removal of Cr(vi) from acidic aqueous solution by ethylenediamine-reduced graphene oxide,,Chemical reduction and removal of Cr(vi) from acidic aqueous solution by ethylenediamine-reduced graphene oxide Abs: 
1577865,Gu et al. 2012,Magnetic polyaniline nanocomposites toward toxic hexavalent chromium removal,,Magnetic polyaniline nanocomposites toward toxic hexavalent chromium removal Abs: 
1577851,O'brien and  Wang 1992,A potentially significant one-electron pathway in the reduction of chromate by glutathione under physiological conditions,,A potentially significant one-electron pathway in the reduction of chromate by glutathione under physiological conditions Abs: 
1577850,Tomlinson et al. 1994,Speciation of toxicologically important transition metals using ion chromatography with inductively coupled plasma mass spectrometric detection,,Speciation of toxicologically important transition metals using ion chromatography with inductively coupled plasma mass spectrometric detection Abs: 
1577849,Zoorob et al. 1995,Evaluation of the direct injection nebulizer in the coupling of high-performance liquid chromatography to inductively coupled plasma mass spectrometry,,Evaluation of the direct injection nebulizer in the coupling of high-performance liquid chromatography to inductively coupled plasma mass spectrometry Abs: 
1577848,Stewart and  Horlick 1996,Investigations into chromium speciation by electrospray mass spectrometry,,Investigations into chromium speciation by electrospray mass spectrometry Abs: 
1577847,Shen and  Wang 1994,Biological Reduction of Chromium by E. Coli,,Biological Reduction of Chromium by E. Coli Abs: 
1577846,Shen and  Wang 1995,Hexavalent Chromium Removal in Two-Stage Bioreactor System,,Hexavalent Chromium Removal in Two-Stage Bioreactor System Abs: 
1577845,Sadaoui et al. 1998,Surfactants for Separation Processes: Enhanced Ultrafiltration,,Surfactants for Separation Processes: Enhanced Ultrafiltration Abs: 
1577844,Wang et al. 2000,Cr(VI) Reduction in Continuous-Flow Coculture Bioreactor,,Cr(VI) Reduction in Continuous-Flow Coculture Bioreactor Abs: 
1577843,Tokala et al. 2008,Subsurface Mobility of Organo–Cr(III) Complexes Formed during Biological Reduction of Cr(VI),,Subsurface Mobility of Organo–Cr(III) Complexes Formed during Biological Reduction of Cr(VI) Abs: 
1577829,Zhao et al. 2009,Effect of Hexavalent Chromium on Performance of Membrane Bioreactor in Wastewater Treatment,,Effect of Hexavalent Chromium on Performance of Membrane Bioreactor in Wastewater Treatment Abs: 
1577827,Tale et al. 2012,Ceric Ammonium Nitrate as the Novel Oxidizing Agent for the Facile Synthesis of (Dichloroiodo)arenes,,Ceric Ammonium Nitrate as the Novel Oxidizing Agent for the Facile Synthesis of (Dichloroiodo)arenes Abs: 
1577826,Saha et al. 2011,"Micellar catalysis on 1,10-phenanthroline promoted hexavalent chromium oxidation of ethanol",,"Micellar catalysis on 1,10-phenanthroline promoted hexavalent chromium oxidation of ethanol Abs: "
1577825,Swarnkar et al. 2012,Sorption of Chromate and Arsenate by Surfactant Modified Erionite (E-SMZ),,Sorption of Chromate and Arsenate by Surfactant Modified Erionite (E-SMZ) Abs: 
1577823,Zachariadis and  Trikas 2012,Speciation of Cr(III) and Cr(VI) using solid phase extraction and determination of total As inductively coupled plasma atomic emission spectrometry,,Speciation of Cr(III) and Cr(VI) using solid phase extraction and determination of total As inductively coupled plasma atomic emission spectrometry Abs: 
1577822,Pyrzynska 2012,Non-chromatographic speciation analysis of chromium in natural waters,,Non-chromatographic speciation analysis of chromium in natural waters Abs: 
1577821,Kumar et al. 2012,Genotoxic and Mutagenic Assessment of Hexavalent Chromium in Fish Following In Vivo Chronic Exposure,,Genotoxic and Mutagenic Assessment of Hexavalent Chromium in Fish Following In Vivo Chronic Exposure Abs: 
1577820,Koch et al. 2012,Insolubility of Cr 2 O 3 in Bioaccessibility Tests Points to Requirement for a New Human Oral Reference Dose for Trivalent Chromium,,Insolubility of Cr 2 O 3 in Bioaccessibility Tests Points to Requirement for a New Human Oral Reference Dose for Trivalent Chromium Abs: 
1577819,Perikamana et al. 2013,Investigation onto feasibility of an adsorbent for chromium abatement with its extended application for real mine drainage water,"The feasibilities of the adsorbents ferrous modified calcined bauxite (FEMCB) and ferric modified calcined bauxite (FRMCB) in the abatement of Cr(VI) was investigated in the present study. The adsorbents were characterized by scanning electron micrographs (SEM), electro diffraction spectra (EDS), X-ray diffraction (XRD), and Fourier transform infrared (FTIR) spectra. Parameter optimization of both adsorbents was done and performance efficiencies in the removal of Cr(VI) were compared. Although pH and temperature seemed to have no significant role in the removal efficiency of FEMCB, sorption by FRMCB was found to be depending on both. The optimum pH and temperature was found to be 5 ± 0.2, and 30°C, respectively. At optimum conditions, both adsorbents demonstrated removal efficiencies of &gt;99% for a concentration of 5 mg L(-1). Sorption of Cr(VI) by FEMCB followed Freundlich isotherm model, while that of FRMCB fitted well with Langmuir isotherm model. The isotherm parameters were optimized by minimizing the error functions. The kinetics of sorption by FEMCB followed a pseudo-second-order model confirming chemisorptive mechanism, while FRMCB followed pseudo-first-order. Thermodynamic study revealed that sorption process was spontaneous and that the rate limiting step was governed by film diffusion. Both the adsorbents showed removal efficiencies of &gt;99% in removing Cr(VI) from real sample of mine drainage water of concentration 1.86 mg L(-1) at optimum conditions.","Investigation onto feasibility of an adsorbent for chromium abatement with its extended application for real mine drainage water Abs: The feasibilities of the adsorbents ferrous modified calcined bauxite (FEMCB) and ferric modified calcined bauxite (FRMCB) in the abatement of Cr(VI) was investigated in the present study. The adsorbents were characterized by scanning electron micrographs (SEM), electro diffraction spectra (EDS), X-ray diffraction (XRD), and Fourier transform infrared (FTIR) spectra. Parameter optimization of both adsorbents was done and performance efficiencies in the removal of Cr(VI) were compared. Although pH and temperature seemed to have no significant role in the removal efficiency of FEMCB, sorption by FRMCB was found to be depending on both. The optimum pH and temperature was found to be 5 ± 0.2, and 30°C, respectively. At optimum conditions, both adsorbents demonstrated removal efficiencies of &gt;99% for a concentration of 5 mg L(-1). Sorption of Cr(VI) by FEMCB followed Freundlich isotherm model, while that of FRMCB fitted well with Langmuir isotherm model. The isotherm parameters were optimized by minimizing the error functions. The kinetics of sorption by FEMCB followed a pseudo-second-order model confirming chemisorptive mechanism, while FRMCB followed pseudo-first-order. Thermodynamic study revealed that sorption process was spontaneous and that the rate limiting step was governed by film diffusion. Both the adsorbents showed removal efficiencies of &gt;99% in removing Cr(VI) from real sample of mine drainage water of concentration 1.86 mg L(-1) at optimum conditions."
1577809,Rawson et al. 2010,Voltammetric Behavior of DNA and Its Derivatives Using Screen Printed Carbon Electrodes and Its Possible Application in Genotoxicity Screening,,Voltammetric Behavior of DNA and Its Derivatives Using Screen Printed Carbon Electrodes and Its Possible Application in Genotoxicity Screening Abs: 
1577806,Wolf et al. 2008,Comparison of Shoemaker–McLean–Pratt and Modified Mehlich Buffer Tests for Lime Requirement on Pennsylvania Soils,,Comparison of Shoemaker–McLean–Pratt and Modified Mehlich Buffer Tests for Lime Requirement on Pennsylvania Soils Abs: 
1577783,Prokisch et al. 1995,A simple and inexpensive method for chromium speciation in soil extracts,,A simple and inexpensive method for chromium speciation in soil extracts Abs: 
1577782,Navarro et al. 2006,Hybrid Properties of Alginate?PEI Adsorbent for Chromium (VI) Removal from Aqueous Solutions,,Hybrid Properties of Alginate?PEI Adsorbent for Chromium (VI) Removal from Aqueous Solutions Abs: 
1577781,Werner et al. 2006,Laboratory Study of Simulated Atmospheric Transformations of Chromium in Ultrafine Combustion Aerosol Particles,,Laboratory Study of Simulated Atmospheric Transformations of Chromium in Ultrafine Combustion Aerosol Particles Abs: 
1577779,Lima et al. 2000,On the Use of the Optothermal Window Technique for the Determination of Low Concentrations of Chromium (VI) and Phosphorus in Water,,On the Use of the Optothermal Window Technique for the Determination of Low Concentrations of Chromium (VI) and Phosphorus in Water Abs: 
1577778,Lunar et al. 1994,Determination of Chromium (VI) in Natural Waters by the Interaction Between Triiodide Ion and Hexadecylpyridinium Chloride Micelles,,Determination of Chromium (VI) in Natural Waters by the Interaction Between Triiodide Ion and Hexadecylpyridinium Chloride Micelles Abs: 
1577776,Orescanin et al. 2006,"Environmental contamination assessment of the surroundings of the ex-ferrochromium smelter Dugi Rat, Croatia","The objective of this study was to chemically characterize the soil samples affected by the dust emission and slag dumping from ferrochromium smelter, as well as uptake of metals by vegetation growing on that soil. There were 38 samples collected altogether, including unpolluted background soil samples, polluted soil samples taken in the vicinity of the factory, slag material, bottom and fly ash. Grass material was also taken from both polluted and unpolluted soil. All samples were analyzed with energy dispersive X-ray fluorescence (EDXRF). The results showed (especially for chromium and manganese) metal concentrations in soil samples taken in the vicinity of the factory increased up to 56 times in relation to normal background soil concentrations. Slag material, fly and bottom ash were highly enriched with chromium, manganese and nickel. There was a significant chromium uptake by vegetation growing on the contaminated soil.","Environmental contamination assessment of the surroundings of the ex-ferrochromium smelter Dugi Rat, Croatia Abs: The objective of this study was to chemically characterize the soil samples affected by the dust emission and slag dumping from ferrochromium smelter, as well as uptake of metals by vegetation growing on that soil. There were 38 samples collected altogether, including unpolluted background soil samples, polluted soil samples taken in the vicinity of the factory, slag material, bottom and fly ash. Grass material was also taken from both polluted and unpolluted soil. All samples were analyzed with energy dispersive X-ray fluorescence (EDXRF). The results showed (especially for chromium and manganese) metal concentrations in soil samples taken in the vicinity of the factory increased up to 56 times in relation to normal background soil concentrations. Slag material, fly and bottom ash were highly enriched with chromium, manganese and nickel. There was a significant chromium uptake by vegetation growing on the contaminated soil."
1577775,Karamalidis et al. 2008,"Characterization of stabilized/solidified refinery oily sludge and incinerated refinery sludge with cement using XRD, SEM and EXAFS","Solidification/stabilization (S/S) of refinery oily sludge and incinerated oily sludge (ash) with cement type I42.5 and II42.5 was investigated using, X-Ray Diffraction (XRD), Scanning Electron Microscopy (SEM) combined with Energy Dispersive Spectroscopy (EDS) and Extended X-ray Absorption Fine Structure (EXAFS). The results showed that delayed ettringite formation (DEF) and major cement hydration reactions occurred. XRD analysis of S/S oily sludge samples revealed cement-bearing solid phases, such as portlandite, calcite, C(3)S, C(2)S and C(4)AF. SEM analysis, confirmed ettringite at solidified oily sludge samples. Solidified ash samples contained ettringite substituted by chromates. However, solid phases found in solidified ash samples with I42.5 cement showed minor variation in type and structure compared to those observed in solidified ash samples with II42.5 cement. Fe K edge EXAFS analysis revealed the presence of iron oxides in both S/S wastes. The comparison between spectra of the S/S resulting materials and the ones of their original components, showed that the first sphere Fe-O distances were longer than in the pure iron oxide thereby providing evidence that the resulting materials were not simple mixtures, but products of a reaction that modified the local environment of iron.","Characterization of stabilized/solidified refinery oily sludge and incinerated refinery sludge with cement using XRD, SEM and EXAFS Abs: Solidification/stabilization (S/S) of refinery oily sludge and incinerated oily sludge (ash) with cement type I42.5 and II42.5 was investigated using, X-Ray Diffraction (XRD), Scanning Electron Microscopy (SEM) combined with Energy Dispersive Spectroscopy (EDS) and Extended X-ray Absorption Fine Structure (EXAFS). The results showed that delayed ettringite formation (DEF) and major cement hydration reactions occurred. XRD analysis of S/S oily sludge samples revealed cement-bearing solid phases, such as portlandite, calcite, C(3)S, C(2)S and C(4)AF. SEM analysis, confirmed ettringite at solidified oily sludge samples. Solidified ash samples contained ettringite substituted by chromates. However, solid phases found in solidified ash samples with I42.5 cement showed minor variation in type and structure compared to those observed in solidified ash samples with II42.5 cement. Fe K edge EXAFS analysis revealed the presence of iron oxides in both S/S wastes. The comparison between spectra of the S/S resulting materials and the ones of their original components, showed that the first sphere Fe-O distances were longer than in the pure iron oxide thereby providing evidence that the resulting materials were not simple mixtures, but products of a reaction that modified the local environment of iron."
1577772,Rad et al. 2004,Reduction of Cr(VI) Using Polyaniline–Polystirene-Divinyl Benzene Gels,,Reduction of Cr(VI) Using Polyaniline–Polystirene-Divinyl Benzene Gels Abs: 
1577771,Kabir-ud-din et al. 2002,Catalytic Effect of Polyoxyethylene t -octylphenol (Triton X-100) Surfactant on the Oxidation of EDTA by Chromic Acid,,Catalytic Effect of Polyoxyethylene t -octylphenol (Triton X-100) Surfactant on the Oxidation of EDTA by Chromic Acid Abs: 
1577770,Lee et al. 2001,THE EFFECT OF HYDRATION ON ADSORPTION AND DESORPTION OF HEAVY METALS IN SOILS,,THE EFFECT OF HYDRATION ON ADSORPTION AND DESORPTION OF HEAVY METALS IN SOILS Abs: 
1577769,Mignani and  Romolini 2002,ABSORPTION SPECTROSCOPY IN THE VISIBLE SPECTRAL RANGE OF TRIVALENT AND HEXAVALENT CHROMIUM IN DISTILLED WATER AND IN BUFFERS AT DIFFERENT pH VALUES,,ABSORPTION SPECTROSCOPY IN THE VISIBLE SPECTRAL RANGE OF TRIVALENT AND HEXAVALENT CHROMIUM IN DISTILLED WATER AND IN BUFFERS AT DIFFERENT pH VALUES Abs: 
1577768,Wang and  Vipulanandan 2001,Solidification/Stabilization of Fe(II)-Treated Cr(VI)-Contaminated Soil,,Solidification/Stabilization of Fe(II)-Treated Cr(VI)-Contaminated Soil Abs: 
1577767,Pamukoglu and  Kargi 2008,Biological Treatment of Cu(II) Containing Synthetic Wastewater in an Activated Sludge Unit: Copper(II) Ion Toxicity,,Biological Treatment of Cu(II) Containing Synthetic Wastewater in an Activated Sludge Unit: Copper(II) Ion Toxicity Abs: 
1577766,Shankar 2009,"Chromium Pollution in the Groundwaters of an Industrial Area in Bangalore, India",,"Chromium Pollution in the Groundwaters of an Industrial Area in Bangalore, India Abs: "
1577765,Shariatmadari et al. 2009,Enhancement of Hexavalent Chromium [Cr(VI)] Remediation from Clayey Soils by Electrokinetics Coupled with a Nano-Sized Zero-Valent Iron Barrier,,Enhancement of Hexavalent Chromium [Cr(VI)] Remediation from Clayey Soils by Electrokinetics Coupled with a Nano-Sized Zero-Valent Iron Barrier Abs: 
1577764,Matey et al. 2000,Chromic Acid Burns,,Chromic Acid Burns Abs: 
1577763,Kalenda et al. 2006,Properties of anticorrosion pigments depending on their chemical composition and PVC value,,Properties of anticorrosion pigments depending on their chemical composition and PVC value Abs: 
1577762,Liu et al. 1992,Effects of trivalent and hexavalent chromium on root growth and cell division of Allium cepa,,Effects of trivalent and hexavalent chromium on root growth and cell division of Allium cepa Abs: 
1577755,Khan and  Puts 2003,In Situ Abiotic Detoxification and Immobilization of Hexavalent Chromium,,In Situ Abiotic Detoxification and Immobilization of Hexavalent Chromium Abs: 
1577754,Mu?ller et al. 2004,Cr-Free Passivation on ZnNi Alloys,,Cr-Free Passivation on ZnNi Alloys Abs: 
1577753,Kim and  Frankel 2007,Effect of Noble Element Alloying on Passivity and Passivity Breakdown of Ni,,Effect of Noble Element Alloying on Passivity and Passivity Breakdown of Ni Abs: 
1577752,Souriau et al. 2008,Characterization of Threading Dislocations in Thin Germanium Layers by Defect Etching: Toward Chromium and HF-Free Solution,,Characterization of Threading Dislocations in Thin Germanium Layers by Defect Etching: Toward Chromium and HF-Free Solution Abs: 
1577751,Ma?hliß et al. 2011,Approaches in Wet Chemical Etching for Defect Delineation in Silicon-on-Insulator Substrates,,Approaches in Wet Chemical Etching for Defect Delineation in Silicon-on-Insulator Substrates Abs: 
1577750,Sharma et al. 2003,Heterogeneous photocatalytic reduction of ferrate(VI) in UV-irradiated titania suspensions: Role in enhancing destruction of nitrogen-containing pollutants,,Heterogeneous photocatalytic reduction of ferrate(VI) in UV-irradiated titania suspensions: Role in enhancing destruction of nitrogen-containing pollutants Abs: 
1577749,Salman et al. 2007,Development of Cerium-based Conversion Coating on AZ31 Magnesium Alloy,,Development of Cerium-based Conversion Coating on AZ31 Magnesium Alloy Abs: 
1577748,Stefaniak et al. 2000,On the Adsorption of Chromium(VI) Ions on Dolomite and ‘Dolomitic Sorbents’,,On the Adsorption of Chromium(VI) Ions on Dolomite and ‘Dolomitic Sorbents’ Abs: 
1577747,Gan 1996,Morphology of Lead(II) and Chromium(III) Reaction Products on Phyllosilicate Surfaces as Determined by Atomic Force Microscopy,,Morphology of Lead(II) and Chromium(III) Reaction Products on Phyllosilicate Surfaces as Determined by Atomic Force Microscopy Abs: 
1577725,Ling et al. 2011,Treatment of municipal landfill leachate with organically modified bentonite,,Treatment of municipal landfill leachate with organically modified bentonite Abs: 
1577724,Motomizu 2012,Computer-controlled fluid-flow chemical analysis (CC-FCA) and its application to environmental analytical chemistry,,Computer-controlled fluid-flow chemical analysis (CC-FCA) and its application to environmental analytical chemistry Abs: 
1577723,Matis et al. 2008,Metal ions biosorption from dilute aqueous solution,,Metal ions biosorption from dilute aqueous solution Abs: 
1577722,Little et al. ,Environmental Toxicology and Risk Assessment: Seventh Volume,,Environmental Toxicology and Risk Assessment: Seventh Volume Abs: 
1577721,Shemirani et al. 2003,Preconcentration and Speciation of Chromium in Water Samples by Atomic Absorption Spectrometry after Cloud-Point Extraction,,Preconcentration and Speciation of Chromium in Water Samples by Atomic Absorption Spectrometry after Cloud-Point Extraction Abs: 
1577720,Mila?i? et al. 2011,Environmental impacts of asphalt mixes with electric arc furnace steel slag,"Electric arc furnace (EAF) steel slag can be used as an alternative high-quality material in road construction. Although asphalts with slag aggregates have been recognized as environmentally acceptable, there is a lack of data concerning the potential leaching of toxic Cr(VI) due to the highly alkaline media of EAF slag. Leaching of selected water extractable metals from slag indicated elevated concentrations of total chromium and Cr(VI). To estimate the environmental impacts of asphalt mixes with slag, leachability tests based on diffusion were performed using pure water and salt water as leaching agents. Compact and ground asphalt composites with natural aggregates, and asphalt composites in which the natural aggregates were completely replaced by slag were prepared. The concentrations of total chromium and Cr(VI) were determined in leachates over a time period of 6 mo. After 1 and 6 mo, the concentrations of some other metals were also determined in the leachates. The results indicated that chromium in leachates from asphalt composites with the addition of slag was present almost solely in its hexavalent form. However, the concentrations were very low (below 25 ?g L) and did not represent an environmental burden. The leaching of other metals from asphalt composites with the addition of slag was negligible. Therefore, the investigated EAF slag can be considered as environmentally safe substitute for natural aggregates in asphalt mixes.","Environmental impacts of asphalt mixes with electric arc furnace steel slag Abs: Electric arc furnace (EAF) steel slag can be used as an alternative high-quality material in road construction. Although asphalts with slag aggregates have been recognized as environmentally acceptable, there is a lack of data concerning the potential leaching of toxic Cr(VI) due to the highly alkaline media of EAF slag. Leaching of selected water extractable metals from slag indicated elevated concentrations of total chromium and Cr(VI). To estimate the environmental impacts of asphalt mixes with slag, leachability tests based on diffusion were performed using pure water and salt water as leaching agents. Compact and ground asphalt composites with natural aggregates, and asphalt composites in which the natural aggregates were completely replaced by slag were prepared. The concentrations of total chromium and Cr(VI) were determined in leachates over a time period of 6 mo. After 1 and 6 mo, the concentrations of some other metals were also determined in the leachates. The results indicated that chromium in leachates from asphalt composites with the addition of slag was present almost solely in its hexavalent form. However, the concentrations were very low (below 25 ?g L) and did not represent an environmental burden. The leaching of other metals from asphalt composites with the addition of slag was negligible. Therefore, the investigated EAF slag can be considered as environmentally safe substitute for natural aggregates in asphalt mixes."
1577719,Jardine et al. 2011,Geochemical Processes Governing the Fate and Transport of Chromium(III) and Chromium(VI) in Soils,,Geochemical Processes Governing the Fate and Transport of Chromium(III) and Chromium(VI) in Soils Abs: 
1577718,Yoon et al. 2009,Photocatalytic reduction of hexavalent chromium (Cr(VI)) using rotating TiO2 mesh,,Photocatalytic reduction of hexavalent chromium (Cr(VI)) using rotating TiO2 mesh Abs: 
1577717,Islam and  Das 2008,Picolinic Acid Assisted Three-Electron Transfer Chromic Acid Oxidation of -Mandelic Acid in Aqueous Micellar Media: A Kinetic Study,,Picolinic Acid Assisted Three-Electron Transfer Chromic Acid Oxidation of -Mandelic Acid in Aqueous Micellar Media: A Kinetic Study Abs: 
1577716,Wang et al. 2001,Effects of the type of sintering atmosphere on the chromium leachability of thermal-treated municipal solid waste incinerator fly ash,"The sintering process offers an opportunity to combine detoxification and resource recovery for the treatment of municipal solid waste (MSW) incinerator fly ash. However, the chromium (Cr) in the sintered fly ash becomes more readily leachable with increasing sintering time and temperature, thus posing severe threats to the environment and human health when the sintered ash is recycled or reused. This study investigated the enhanced leachability of fly ash containing Cr, by heating the chromium (III) oxide (Cr2O3)-spiked fly ash to 800 degrees C in atmospheres containing air, nitrogen gas (N2), and 5% H2 + 95% N2, respectively. The results indicated that trivalent chromium was converted to its soluble hexavalent form during sintering in the air atmosphere; whereas sintering in a nitrogen atmosphere significantly reduced the leachability of Cr due to lack of oxygen (O2) to oxidize. The effects of the sintering temperature on the total chromium content and the leaching concentration in the toxicity characteristic leaching procedure (TCLP) extract are also discussed.","Effects of the type of sintering atmosphere on the chromium leachability of thermal-treated municipal solid waste incinerator fly ash Abs: The sintering process offers an opportunity to combine detoxification and resource recovery for the treatment of municipal solid waste (MSW) incinerator fly ash. However, the chromium (Cr) in the sintered fly ash becomes more readily leachable with increasing sintering time and temperature, thus posing severe threats to the environment and human health when the sintered ash is recycled or reused. This study investigated the enhanced leachability of fly ash containing Cr, by heating the chromium (III) oxide (Cr2O3)-spiked fly ash to 800 degrees C in atmospheres containing air, nitrogen gas (N2), and 5% H2 + 95% N2, respectively. The results indicated that trivalent chromium was converted to its soluble hexavalent form during sintering in the air atmosphere; whereas sintering in a nitrogen atmosphere significantly reduced the leachability of Cr due to lack of oxygen (O2) to oxidize. The effects of the sintering temperature on the total chromium content and the leaching concentration in the toxicity characteristic leaching procedure (TCLP) extract are also discussed."
1577715,Levina et al. 2000,Disproportionation and nuclease activity of bis[2-ethyl-2-hydroxybutanoato(2-)]oxochromate(V) in neutral aqueous solutions,"Complex 1, [Cr(V)O(ehba)2]- (ehba = 2-ethyl-2-hydroxybutanoate(2-)) is the most studied model compound of relevance to the biological activity of Cr(V) with regard to Cr-induced cancers. The first detailed kinetic study of disproportionation of 1 under neutral pH conditions (pH 6.0-8.0, [NaClO4] = 1.0 M, 37 degrees C) is reported. Kinetic data were collected by stopped-flow and conventional UV-vis spectroscopies and processed by the global analysis method. The disproportionation, which follows the stoichiometry 3Cr(V) --&gt; 2Cr(VI) + Cr(III) (1), leads to release of 5 mol of H+/3 mol of Cr(V). Reaction 1 is accelerated by phosphate, but is not affected by acetate, HEPES, or Tris buffers. Initial rates of Cr(V) decay are directly proportional to [Cr(V)]0 (0.020-1.0 mM); they increase with an increase in the pH values and decrease in the presence of a large excess of ehba ligand. The first direct evidence for the formation of Cr(IV) intermediates in reaction 1 has been obtained; however, their UV-vis spectral properties were different from those of the well-characterized Cr(IV)-ehba complexes. The Cr(III) products of reaction I in phosphate buffers differ from those in the other buffers. A mechanism is proposed for reaction 1 on the basis of kinetic modeling. Influences of the reaction time and conditions on the extent of plasmid DNA cleavage induced by 1 have been studied under conditions corresponding to those of the kinetic studies. A comparison of the kinetic and DNA cleavage results has shown that direct interaction of 1 with the phosphate backbone of DNA is the most likely first step in the mechanism of DNA cleavage in neutral media. Small additions of Mn(II) ((0.01-0.1)[Cr(V)]0) did not affect the rate and stoichiometry of reaction 1, but suppressed the formation of Cr(IV) intermediates (presumably due to the catalysis of Cr(IV) disproportionation). However, much higher concentrations of Mn(II) ((0.1-1.0)[Cr(V)]0) were required to inhibit DNA cleavage induced by 1. Thus, contrary to previous reports (Sugden, K. D.; Wetterhahn, K. E. J. Am. Chem. Soc. 1996, 118, 10811-10818), inhibition by Mn(II) does not indicate a key role of Cr(IV) in Cr(V)-induced DNA cleavage.","Disproportionation and nuclease activity of bis[2-ethyl-2-hydroxybutanoato(2-)]oxochromate(V) in neutral aqueous solutions Abs: Complex 1, [Cr(V)O(ehba)2]- (ehba = 2-ethyl-2-hydroxybutanoate(2-)) is the most studied model compound of relevance to the biological activity of Cr(V) with regard to Cr-induced cancers. The first detailed kinetic study of disproportionation of 1 under neutral pH conditions (pH 6.0-8.0, [NaClO4] = 1.0 M, 37 degrees C) is reported. Kinetic data were collected by stopped-flow and conventional UV-vis spectroscopies and processed by the global analysis method. The disproportionation, which follows the stoichiometry 3Cr(V) --&gt; 2Cr(VI) + Cr(III) (1), leads to release of 5 mol of H+/3 mol of Cr(V). Reaction 1 is accelerated by phosphate, but is not affected by acetate, HEPES, or Tris buffers. Initial rates of Cr(V) decay are directly proportional to [Cr(V)]0 (0.020-1.0 mM); they increase with an increase in the pH values and decrease in the presence of a large excess of ehba ligand. The first direct evidence for the formation of Cr(IV) intermediates in reaction 1 has been obtained; however, their UV-vis spectral properties were different from those of the well-characterized Cr(IV)-ehba complexes. The Cr(III) products of reaction I in phosphate buffers differ from those in the other buffers. A mechanism is proposed for reaction 1 on the basis of kinetic modeling. Influences of the reaction time and conditions on the extent of plasmid DNA cleavage induced by 1 have been studied under conditions corresponding to those of the kinetic studies. A comparison of the kinetic and DNA cleavage results has shown that direct interaction of 1 with the phosphate backbone of DNA is the most likely first step in the mechanism of DNA cleavage in neutral media. Small additions of Mn(II) ((0.01-0.1)[Cr(V)]0) did not affect the rate and stoichiometry of reaction 1, but suppressed the formation of Cr(IV) intermediates (presumably due to the catalysis of Cr(IV) disproportionation). However, much higher concentrations of Mn(II) ((0.1-1.0)[Cr(V)]0) were required to inhibit DNA cleavage induced by 1. Thus, contrary to previous reports (Sugden, K. D.; Wetterhahn, K. E. J. Am. Chem. Soc. 1996, 118, 10811-10818), inhibition by Mn(II) does not indicate a key role of Cr(IV) in Cr(V)-induced DNA cleavage."
1577714,Paleologos et al. 2001,An optimised single-reagent method for the speciation of chromium by flame atomic absorption spectrometry based on surfactant micelle-mediated methodology,"The toxicity of chromium in the environment is dependent on the species in which it exists. This paper outlines a method for the analysis of the oxidation states of Cr employing a suitable chelating agent and the cloud point phenomenon for Cr(VI) and total Cr analysis. The method involves preconcentration of metal chelates followed by air-acetylene flame atomic absorption spectrometric analysis. The chelating agent chosen for this task is the ammonium pyrrolidinedithiocarbamate, which reacts with either Cr(VI) or total Cr under specific experimental conditions. The condensed surfactant phase with the metal chelate(s) is introduced into a flame atomic absorption spectrometer, whereby discrimination of Cr species is feasible by calculating the Cr(III) concentration from the difference between total Cr and Cr(VI). A multivariate design was employed to study the variables affecting the overall analytical performance for total Cr assay. The analytical curves are rectilinear up to 100 micrograms l-1 for both oxidation states of the metal. The limits of detection are 0.6 microgram l-1 and the relative standard deviation (n = 5) at a concentration of 30 micrograms l-1 for both species is around 2.0%. The method was validated by analysing BCR 544 reference material certified for both Cr species. High recoveries in the range 96-107% were attained for the environmental and biological samples tested.","An optimised single-reagent method for the speciation of chromium by flame atomic absorption spectrometry based on surfactant micelle-mediated methodology Abs: The toxicity of chromium in the environment is dependent on the species in which it exists. This paper outlines a method for the analysis of the oxidation states of Cr employing a suitable chelating agent and the cloud point phenomenon for Cr(VI) and total Cr analysis. The method involves preconcentration of metal chelates followed by air-acetylene flame atomic absorption spectrometric analysis. The chelating agent chosen for this task is the ammonium pyrrolidinedithiocarbamate, which reacts with either Cr(VI) or total Cr under specific experimental conditions. The condensed surfactant phase with the metal chelate(s) is introduced into a flame atomic absorption spectrometer, whereby discrimination of Cr species is feasible by calculating the Cr(III) concentration from the difference between total Cr and Cr(VI). A multivariate design was employed to study the variables affecting the overall analytical performance for total Cr assay. The analytical curves are rectilinear up to 100 micrograms l-1 for both oxidation states of the metal. The limits of detection are 0.6 microgram l-1 and the relative standard deviation (n = 5) at a concentration of 30 micrograms l-1 for both species is around 2.0%. The method was validated by analysing BCR 544 reference material certified for both Cr species. High recoveries in the range 96-107% were attained for the environmental and biological samples tested."
1577713,Kareus et al. 2001,Release of Cr(III) from Cr(III) picolinate upon metabolic activation,"Hexavalent and trivalent chromium are released into the environment from a number of different industrial activities. It is known that Cr(VI) can be reduced and subsequently complexed by humic acids to produce Cr(III) humic acid complexes in the soil and aquatic environments. The metabolic fate of Cr(III) humic acid complexes and other Cr(III) organic complexes in mammalian systems is unknown. Therefore, Cr(III) picolinate was chosen as a model complex for Cr(III) humic acid complexes and other environmentally relevant Cr(III) complexes. Both human hepatocyte microsomes and primary cultures of chick hepatocytes were used to generate metabolites of Cr(III) picolinate. The results from both of these treatments show that a significant amount of Cr(III) is released (66 and 100%, respectively) and that N-1-methylpicotinamide is the primary organic metabolite from this compound. These data suggest that the populations of humans who are exposed Cr(III) picolinate or other environmentally relevant organic Cr(III) complexes, such as Cr(III) humic acid complexes, are potentially accumulating high levels of Cr(III) intracellularly. This intracellular accumulation of Cr(III) can result in the formation of covalent bonds between Cr(III) and DNA and/or other macromolecules, causing genotoxic effects. These data should be considered when assessing the risk of an area contaminated with chromium.","Release of Cr(III) from Cr(III) picolinate upon metabolic activation Abs: Hexavalent and trivalent chromium are released into the environment from a number of different industrial activities. It is known that Cr(VI) can be reduced and subsequently complexed by humic acids to produce Cr(III) humic acid complexes in the soil and aquatic environments. The metabolic fate of Cr(III) humic acid complexes and other Cr(III) organic complexes in mammalian systems is unknown. Therefore, Cr(III) picolinate was chosen as a model complex for Cr(III) humic acid complexes and other environmentally relevant Cr(III) complexes. Both human hepatocyte microsomes and primary cultures of chick hepatocytes were used to generate metabolites of Cr(III) picolinate. The results from both of these treatments show that a significant amount of Cr(III) is released (66 and 100%, respectively) and that N-1-methylpicotinamide is the primary organic metabolite from this compound. These data suggest that the populations of humans who are exposed Cr(III) picolinate or other environmentally relevant organic Cr(III) complexes, such as Cr(III) humic acid complexes, are potentially accumulating high levels of Cr(III) intracellularly. This intracellular accumulation of Cr(III) can result in the formation of covalent bonds between Cr(III) and DNA and/or other macromolecules, causing genotoxic effects. These data should be considered when assessing the risk of an area contaminated with chromium."
1577712,Kieber et al. 2002,Chromium speciation in rainwater: temporal variability and atmospheric deposition,"The concentrations of the various chromium species were determined in 89 rainwater samples collected in Wilmington, NC, from October 1, 1999, to December 31, 2001. Volume-weighted annual average concentrations of Cr(total), particulate Cr, Cr(III)(aq), and Cr(VI)(aq) were 4.6, 2.2, 0.8, and 1.2 nM, respectively. There was distinct seasonal and diurnal variability in the concentrations of the various chromium species. Chromium emissions to the global atmosphere by both natural and anthropogenic sources are estimated to be 2.2 x 10(9) mol/yr. Using our rainwater concentration data along with other published rainwater Cr concentrations and an estimate for total global annual rain, the total global flux of chromium removed from the atmosphere via wet deposition is 2.1 x 10(9) mol/yr. This represents complete removal of Cr and indicates that essentially all chromium released into the global atmosphere is removed via rain. About half this chromium is dissolved with roughly equal concentrations of toxic Cr(VI) and relatively harmless Cr(III) species.","Chromium speciation in rainwater: temporal variability and atmospheric deposition Abs: The concentrations of the various chromium species were determined in 89 rainwater samples collected in Wilmington, NC, from October 1, 1999, to December 31, 2001. Volume-weighted annual average concentrations of Cr(total), particulate Cr, Cr(III)(aq), and Cr(VI)(aq) were 4.6, 2.2, 0.8, and 1.2 nM, respectively. There was distinct seasonal and diurnal variability in the concentrations of the various chromium species. Chromium emissions to the global atmosphere by both natural and anthropogenic sources are estimated to be 2.2 x 10(9) mol/yr. Using our rainwater concentration data along with other published rainwater Cr concentrations and an estimate for total global annual rain, the total global flux of chromium removed from the atmosphere via wet deposition is 2.1 x 10(9) mol/yr. This represents complete removal of Cr and indicates that essentially all chromium released into the global atmosphere is removed via rain. About half this chromium is dissolved with roughly equal concentrations of toxic Cr(VI) and relatively harmless Cr(III) species."
1577695,Tucker et al. 2003,Influence of form and quantity of chromium on the development and survival of two silkworm (Bombyx mori L.) races,"Growth inhibitory activity has proven important in Qiufeng x Baiyu and Qingsong x Haoyue silkworm larvae. The consumption of mulberry leaves was reduced in both silkworm races while Qiufeng x Baiyu larvae showed the higher reduction in leaf consumption. From the results obtained, it was revealed that even at low concentrations of 400 mg/L of either Cr(III) or Cr(VI) ions, growth of Qiufeng x Baiyu and Qingsong x Haoyue was significantly depressed. Depression in relative growth index (RGI) and high death rate in both silkworm races indicated that the different concentrations of the two ions used caused their growth inhibitions. Through linear regression analysis, the EC50 (concentration of the compound that caused 50% reduction) was interpolated for both tested compounds. EC50 (mg/L) of Cr(III) ions in Qiufeng x Baiyu and Qingsong x Haoyue were 800 and 600 respectively. EC50 (mg/L) of Cr(VI) ions in Qiufeng x Baiyu and Qingsong x Haoyue was 600 and 316 respectively. According to the analysis of relative growth index, and an analysis of linear regression technique for measuring the growth of the silkworm races, it was indicated that the form of Cr affected growth rates, growth inhibition responses of the larvae, and toxicological effects. Thus, form and quantity of Cr accumulating in silkworms reared with contaminated leaves are likely to influence their population dynamics.","Influence of form and quantity of chromium on the development and survival of two silkworm (Bombyx mori L.) races Abs: Growth inhibitory activity has proven important in Qiufeng x Baiyu and Qingsong x Haoyue silkworm larvae. The consumption of mulberry leaves was reduced in both silkworm races while Qiufeng x Baiyu larvae showed the higher reduction in leaf consumption. From the results obtained, it was revealed that even at low concentrations of 400 mg/L of either Cr(III) or Cr(VI) ions, growth of Qiufeng x Baiyu and Qingsong x Haoyue was significantly depressed. Depression in relative growth index (RGI) and high death rate in both silkworm races indicated that the different concentrations of the two ions used caused their growth inhibitions. Through linear regression analysis, the EC50 (concentration of the compound that caused 50% reduction) was interpolated for both tested compounds. EC50 (mg/L) of Cr(III) ions in Qiufeng x Baiyu and Qingsong x Haoyue were 800 and 600 respectively. EC50 (mg/L) of Cr(VI) ions in Qiufeng x Baiyu and Qingsong x Haoyue was 600 and 316 respectively. According to the analysis of relative growth index, and an analysis of linear regression technique for measuring the growth of the silkworm races, it was indicated that the form of Cr affected growth rates, growth inhibition responses of the larvae, and toxicological effects. Thus, form and quantity of Cr accumulating in silkworms reared with contaminated leaves are likely to influence their population dynamics."
1577694,Sharma et al. 2008,Removal of chromium by riverbed sand from water and wastewater: effect of important parameters,"Application of riverbed sand, a non-toxic substance for the removal of Cr(VI) for aqueous solutions has been investigated. Removal of Cr(VI) was dependent on initial concentration and removal increased from 43.2% to 74.3% by decreasing initial concentration from 7.5x10(-5) M to 1.0x10(-5) M at 25 degrees C, 1.0x10(-2) M NaClO4 ionic strength and 100 rpm. Higher removal was obtained at particles of smaller sizes of the adsorbent. Removal decreased from 74.3% to 40.7% by increasing temperature from 25 degrees C to 35 degrees C exhibiting exothermic nature of the process of removal. Thermodynamic parameters, namely change in free energy (DeltaG degrees), enthalpy (DeltaH degrees) and entropy (DeltaS degrees), were calculated and were found to be -0.81 kcal mol(-1), -17.21 kcal mol(-1) and 56.94 cal mol(-1), respectively at 25 degrees C. pH of the solution has pronounced effect on the removal and higher removal was obtained in acidic pH ranges, maximum (74.3%) being at 2.5 pH.","Removal of chromium by riverbed sand from water and wastewater: effect of important parameters Abs: Application of riverbed sand, a non-toxic substance for the removal of Cr(VI) for aqueous solutions has been investigated. Removal of Cr(VI) was dependent on initial concentration and removal increased from 43.2% to 74.3% by decreasing initial concentration from 7.5x10(-5) M to 1.0x10(-5) M at 25 degrees C, 1.0x10(-2) M NaClO4 ionic strength and 100 rpm. Higher removal was obtained at particles of smaller sizes of the adsorbent. Removal decreased from 74.3% to 40.7% by increasing temperature from 25 degrees C to 35 degrees C exhibiting exothermic nature of the process of removal. Thermodynamic parameters, namely change in free energy (DeltaG degrees), enthalpy (DeltaH degrees) and entropy (DeltaS degrees), were calculated and were found to be -0.81 kcal mol(-1), -17.21 kcal mol(-1) and 56.94 cal mol(-1), respectively at 25 degrees C. pH of the solution has pronounced effect on the removal and higher removal was obtained in acidic pH ranges, maximum (74.3%) being at 2.5 pH."
1577693,Hasan et al. 2008,Removal of Cr(VI) from aqueous solutions using agricultural waste 'maize bran',"Novel biosorbent 'maize bran' has been successfully utilized for the removal of Cr(VI) from aqueous solution. The effect of different parameters such as contact time, sorbate concentration, pH of the medium and temperature were investigated and maximum uptake of Cr(VI) was 312.52 (mgg(-1)) at pH 2.0, initial Cr(VI) concentration of 200mgL(-1) and temperature of 40 degrees C. Effect of pH showed that maize bran was not only removing Cr(VI) from aqueous solution but also reducing toxic Cr(VI) into less toxic Cr(III). The sorption kinetics was tested with first order reversible, pseudo-first order and pseudo-second order reaction and it was found that Cr(VI) uptake process followed the pseudo-second order rate expression. Mass transfer of Cr(VI) from bulk to the solid phase (maize bran) was studied at different temperatures. Different thermodynamic parameters, viz., DeltaG degrees , DeltaH degrees and DeltaS degrees have also been evaluated and it has been found that the sorption was feasible, spontaneous and endothermic in nature. The Langmuir and Freundlich equations for describing sorption equilibrium were applied and it was found that the process was well described by Langmuir isotherm. Desorption studies was also carried out and found that complete desorption of Cr(VI) took place at pH of 9.5.","Removal of Cr(VI) from aqueous solutions using agricultural waste 'maize bran' Abs: Novel biosorbent 'maize bran' has been successfully utilized for the removal of Cr(VI) from aqueous solution. The effect of different parameters such as contact time, sorbate concentration, pH of the medium and temperature were investigated and maximum uptake of Cr(VI) was 312.52 (mgg(-1)) at pH 2.0, initial Cr(VI) concentration of 200mgL(-1) and temperature of 40 degrees C. Effect of pH showed that maize bran was not only removing Cr(VI) from aqueous solution but also reducing toxic Cr(VI) into less toxic Cr(III). The sorption kinetics was tested with first order reversible, pseudo-first order and pseudo-second order reaction and it was found that Cr(VI) uptake process followed the pseudo-second order rate expression. Mass transfer of Cr(VI) from bulk to the solid phase (maize bran) was studied at different temperatures. Different thermodynamic parameters, viz., DeltaG degrees , DeltaH degrees and DeltaS degrees have also been evaluated and it has been found that the sorption was feasible, spontaneous and endothermic in nature. The Langmuir and Freundlich equations for describing sorption equilibrium were applied and it was found that the process was well described by Langmuir isotherm. Desorption studies was also carried out and found that complete desorption of Cr(VI) took place at pH of 9.5."
1577690,Kantarli and  Yanik 2010,Activated carbon from leather shaving wastes and its application in removal of toxic materials,"In this study, utilization of a solid waste as raw material for activated carbon production was investigated. For this purpose, activated carbons were produced from chromium and vegetable tanned leather shaving wastes by physical and chemical activation methods. A detailed analysis of the surface properties of the activated carbons including acidity, total surface area, extent of microporosity and mesoporosity was presented. The activated carbon produced from vegetable tanned leather shaving waste produced has a higher surface area and micropore volume than the activated carbon produced from chromium tanned leather shaving waste. The potential application of activated carbons obtained from vegetable tanned shavings as adsorbent for removal of water pollutants have been checked for phenol, methylene blue, and Cr(VI). Adsorption capacities of activated carbons were found to be comparable to that of activated carbons derived from biomass.","Activated carbon from leather shaving wastes and its application in removal of toxic materials Abs: In this study, utilization of a solid waste as raw material for activated carbon production was investigated. For this purpose, activated carbons were produced from chromium and vegetable tanned leather shaving wastes by physical and chemical activation methods. A detailed analysis of the surface properties of the activated carbons including acidity, total surface area, extent of microporosity and mesoporosity was presented. The activated carbon produced from vegetable tanned leather shaving waste produced has a higher surface area and micropore volume than the activated carbon produced from chromium tanned leather shaving waste. The potential application of activated carbons obtained from vegetable tanned shavings as adsorbent for removal of water pollutants have been checked for phenol, methylene blue, and Cr(VI). Adsorption capacities of activated carbons were found to be comparable to that of activated carbons derived from biomass."
1577689,Hsu et al. 2010,Cr(VI) removal on fungal biomass of Neurospora crassa: the importance of dissolved organic carbons derived from the biomass to Cr(VI) reduction,"Interactions of toxic Cr(VI) with renewable biomaterials are considered an important pathway for Cr(VI) removal in ecosystems. Biomaterials are susceptible to dissolution, and their dissolved derivatives may provide an alternative to surface-involved pathway for scavenging of Cr(VI). In this study, dissolved organic carbon (DOC) derived from Neurospora crassa biomass was investigated. The proportion of Cr(VI) reduction by DOC to that on biomass was determined to evaluate the importance of DOC to Cr(VI) reduction. A rapid increase in DOC concentration from 145.6 to 193.7 mg L(-1) was observed when N. crassa-biomass was immersed in 0.01 M KCl solution at pH of 1-5, and polysaccharides, peptides, and glycoproteins with carboxyl, amide, and -NH functional groups, are the major compositions of DOC. On reaction of 96.2 microM Cr(VI) with N. crassa-biomass or DOC, it was estimated that DOC contributed approximately 53.8-59.5% of the total Cr(VI) reduction on biomass in the dark. Illumination enhanced Cr(VI) reduction via photo-oxidation of biomass/DOC under aeration conditions, which formed superoxide for Cr(VI) reduction. At pH 1, photoinduced Cr(VI) reduction by DOC proceeded more rapidly than reduction on the biomass surface. However, at pH &gt;3, with a decrease in Cr(VI) reduction by DOC, photon-excited biomass may become an important electron source for Cr(VI) photoreduction.","Cr(VI) removal on fungal biomass of Neurospora crassa: the importance of dissolved organic carbons derived from the biomass to Cr(VI) reduction Abs: Interactions of toxic Cr(VI) with renewable biomaterials are considered an important pathway for Cr(VI) removal in ecosystems. Biomaterials are susceptible to dissolution, and their dissolved derivatives may provide an alternative to surface-involved pathway for scavenging of Cr(VI). In this study, dissolved organic carbon (DOC) derived from Neurospora crassa biomass was investigated. The proportion of Cr(VI) reduction by DOC to that on biomass was determined to evaluate the importance of DOC to Cr(VI) reduction. A rapid increase in DOC concentration from 145.6 to 193.7 mg L(-1) was observed when N. crassa-biomass was immersed in 0.01 M KCl solution at pH of 1-5, and polysaccharides, peptides, and glycoproteins with carboxyl, amide, and -NH functional groups, are the major compositions of DOC. On reaction of 96.2 microM Cr(VI) with N. crassa-biomass or DOC, it was estimated that DOC contributed approximately 53.8-59.5% of the total Cr(VI) reduction on biomass in the dark. Illumination enhanced Cr(VI) reduction via photo-oxidation of biomass/DOC under aeration conditions, which formed superoxide for Cr(VI) reduction. At pH 1, photoinduced Cr(VI) reduction by DOC proceeded more rapidly than reduction on the biomass surface. However, at pH &gt;3, with a decrease in Cr(VI) reduction by DOC, photon-excited biomass may become an important electron source for Cr(VI) photoreduction."
1577688,Han et al. 2010,Physiological and transcriptional studies of Cr(VI) reduction under aerobic and denitrifying conditions by an aquifer-derived pseudomonad,"Cr(VI) is a widespread groundwater contaminant that is a potent toxin, mutagen, and carcinogen. In situ reductive immobilization is a favored approach for Cr(VI) bioremediation, and Cr(VI) reduction has been reported in a variety of aerobic, facultative, and anaerobic bacteria, including a number of pseudomonads. However, studies comparing Cr(VI) reduction under aerobic and denitrifying conditions in the same organism are not available. We have conducted studies with strain RCH2, a bacterium similar to Pseudomonas stutzeri that we isolated from a Cr-contaminated aquifer. Cell suspension studies with lactate demonstrated that Cr(VI) reduction could occur under either denitrifying or aerobic conditions (at comparable specific rates) and that reduction was at least 20-fold more rapid when the terminal electron acceptor (i.e., nitrate or O(2)) was present. Our results suggest that Cr(VI) reduction by strain RCH2 under either aerobic or denitrifying conditions is primarily cometabolic in the sense that the physiological electron acceptor (oxygen or nitrate) appears to be required. Under both aerobic and denitrifying conditions, the gene(s) associated with chromate reduction are not inducible by Cr. Continuous culture (chemostat) studies showed strong correlations (r(2) values &gt;0.93) between nitrate reduction rate and the transcript copy number of either nirS (cytochrome cd(1) nitrite reductase) or narG (nitrate reductase ? subunit). As our studies indicate that anaerobic Cr(VI) reduction by this pseudomonad requires active denitrification and that denitrification and chromate reduction rates are highly correlated (r(2) &gt; 0.99), monitoring expression of such denitrification genes in biostimulated aquifers could provide valuable proxy information for in situ chromate reduction by similar bacteria even if the specific genes involved in chromate reduction have not been identified. We also report incomplete removal of reduced Cr from solution and on artifacts in the widely used diphenylcarbazide assay for Cr(VI), most notably, its complete inactivation in the presence of millimolar nitrite.","Physiological and transcriptional studies of Cr(VI) reduction under aerobic and denitrifying conditions by an aquifer-derived pseudomonad Abs: Cr(VI) is a widespread groundwater contaminant that is a potent toxin, mutagen, and carcinogen. In situ reductive immobilization is a favored approach for Cr(VI) bioremediation, and Cr(VI) reduction has been reported in a variety of aerobic, facultative, and anaerobic bacteria, including a number of pseudomonads. However, studies comparing Cr(VI) reduction under aerobic and denitrifying conditions in the same organism are not available. We have conducted studies with strain RCH2, a bacterium similar to Pseudomonas stutzeri that we isolated from a Cr-contaminated aquifer. Cell suspension studies with lactate demonstrated that Cr(VI) reduction could occur under either denitrifying or aerobic conditions (at comparable specific rates) and that reduction was at least 20-fold more rapid when the terminal electron acceptor (i.e., nitrate or O(2)) was present. Our results suggest that Cr(VI) reduction by strain RCH2 under either aerobic or denitrifying conditions is primarily cometabolic in the sense that the physiological electron acceptor (oxygen or nitrate) appears to be required. Under both aerobic and denitrifying conditions, the gene(s) associated with chromate reduction are not inducible by Cr. Continuous culture (chemostat) studies showed strong correlations (r(2) values &gt;0.93) between nitrate reduction rate and the transcript copy number of either nirS (cytochrome cd(1) nitrite reductase) or narG (nitrate reductase ? subunit). As our studies indicate that anaerobic Cr(VI) reduction by this pseudomonad requires active denitrification and that denitrification and chromate reduction rates are highly correlated (r(2) &gt; 0.99), monitoring expression of such denitrification genes in biostimulated aquifers could provide valuable proxy information for in situ chromate reduction by similar bacteria even if the specific genes involved in chromate reduction have not been identified. We also report incomplete removal of reduced Cr from solution and on artifacts in the widely used diphenylcarbazide assay for Cr(VI), most notably, its complete inactivation in the presence of millimolar nitrite."
1577687,Ramaswami et al. 2011,The polyomavirus BK large T-antigen-derived peptide elicits an HLA-DR promiscuous and polyfunctional CD4+ T-cell response,"BK virus (BKV) nephropathy and hemorrhagic cystitis are increasingly recognized causes of disease in renal and hematopoietic stem cell transplant recipients, respectively. Functional characterization of the immune response to BKV is important for clinical diagnosis, prognosis, and vaccine design. A peptide mix (PepMix) and overlapping (OPP) or random (RPP) peptide pools derived from BKV large T antigen (LTA) were used to restimulate 14-day-expanded peripheral blood mononuclear cells (PBMC) from 27 healthy control subjects in gamma interferon (IFN-?)-specific enzyme-linked immunospot (ELISPOT) assays. A T-cell response to LTA PepMix was detected in 15/27 subjects. A response was frequently observed with peptides derived from the helicase domain (9/15 subjects), while the DNA binding and host range domains were immunologically inert (0/15 subjects). For all nine subjects who responded to LTA peptide pools, the immune response could be explained largely by a 15-mer peptide designated P313. P313-specific CD4(+) T-cell clones demonstrated (i) stringent LTA peptide specificity; (ii) promiscuous recognition in the context of HLA-DR alleles; (iii) cross recognition of homologous peptides from the polyomavirus simian virus 40 (SV40); (iv) an effector memory phenotype, CD107a expression, and intracellular production of IFN-? and tumor necrosis factor alpha (TNF-?); (v) cytotoxic activity in a chromium release assay; and (vi) the ability to directly present cognate antigen to autologous T cells. In conclusion, T-cell-mediated immunity to BKV in healthy subjects is associated with a polyfunctional population of CD4(+) T cells with dual T-helper and T-cytotoxic properties. HLA class II promiscuity in antigen presentation makes the targeted LTA peptide sequence a suitable candidate for inclusion in immunotherapy protocols.","The polyomavirus BK large T-antigen-derived peptide elicits an HLA-DR promiscuous and polyfunctional CD4+ T-cell response Abs: BK virus (BKV) nephropathy and hemorrhagic cystitis are increasingly recognized causes of disease in renal and hematopoietic stem cell transplant recipients, respectively. Functional characterization of the immune response to BKV is important for clinical diagnosis, prognosis, and vaccine design. A peptide mix (PepMix) and overlapping (OPP) or random (RPP) peptide pools derived from BKV large T antigen (LTA) were used to restimulate 14-day-expanded peripheral blood mononuclear cells (PBMC) from 27 healthy control subjects in gamma interferon (IFN-?)-specific enzyme-linked immunospot (ELISPOT) assays. A T-cell response to LTA PepMix was detected in 15/27 subjects. A response was frequently observed with peptides derived from the helicase domain (9/15 subjects), while the DNA binding and host range domains were immunologically inert (0/15 subjects). For all nine subjects who responded to LTA peptide pools, the immune response could be explained largely by a 15-mer peptide designated P313. P313-specific CD4(+) T-cell clones demonstrated (i) stringent LTA peptide specificity; (ii) promiscuous recognition in the context of HLA-DR alleles; (iii) cross recognition of homologous peptides from the polyomavirus simian virus 40 (SV40); (iv) an effector memory phenotype, CD107a expression, and intracellular production of IFN-? and tumor necrosis factor alpha (TNF-?); (v) cytotoxic activity in a chromium release assay; and (vi) the ability to directly present cognate antigen to autologous T cells. In conclusion, T-cell-mediated immunity to BKV in healthy subjects is associated with a polyfunctional population of CD4(+) T cells with dual T-helper and T-cytotoxic properties. HLA class II promiscuity in antigen presentation makes the targeted LTA peptide sequence a suitable candidate for inclusion in immunotherapy protocols."
1577686,Wu et al. 2012,Chromium exhibits adverse effects at environmental relevant concentrations in chronic toxicity assay system of nematode Caenorhabditis elegans,"Here we investigated whether the assay system (10-d) in Caenorhabditis elegans can be used to evaluate chronic toxicity of chromium (Cr(VI)) at environmental relevant concentrations ranging from 5.2 ?g L(-1) to 260 ?g L(-1). The results indicated that lethality, locomotion behavior as revealed by head thrash, body bend, and forward turn, metabolism as revealed by pumping rate and mean defecation cycle length, intestinal autofluorescence, and ROS production were severely altered in Cr chronically exposed nematodes at environmental relevant concentrations. The most surprising observations were that head thrash, body bend, intestinal autofluorescence, and ROS production in 13 ?g L(-1) Cr exposed nematodes were significantly influenced. The observed adverse effects of Cr on survival, locomotion behavior, and metabolism were largely due to forming severe intestinal autofluorescence and ROS production. Therefore, our findings demonstrate the usefulness of chronic toxicity assay system in C. elegans in evaluating the chronic toxicity of toxicants at environmental relevant concentrations.","Chromium exhibits adverse effects at environmental relevant concentrations in chronic toxicity assay system of nematode Caenorhabditis elegans Abs: Here we investigated whether the assay system (10-d) in Caenorhabditis elegans can be used to evaluate chronic toxicity of chromium (Cr(VI)) at environmental relevant concentrations ranging from 5.2 ?g L(-1) to 260 ?g L(-1). The results indicated that lethality, locomotion behavior as revealed by head thrash, body bend, and forward turn, metabolism as revealed by pumping rate and mean defecation cycle length, intestinal autofluorescence, and ROS production were severely altered in Cr chronically exposed nematodes at environmental relevant concentrations. The most surprising observations were that head thrash, body bend, intestinal autofluorescence, and ROS production in 13 ?g L(-1) Cr exposed nematodes were significantly influenced. The observed adverse effects of Cr on survival, locomotion behavior, and metabolism were largely due to forming severe intestinal autofluorescence and ROS production. Therefore, our findings demonstrate the usefulness of chronic toxicity assay system in C. elegans in evaluating the chronic toxicity of toxicants at environmental relevant concentrations."
1577685,Mila?i? et al. 2012,Environmental impact of toxic elements in red mud studied by fractionation and speciation procedures,"Aluminum (Al) is mostly produced from bauxite ore, which contains up to 70% of Al(2)O(3) (alumina). Before alumina is refined to aluminum metal, it is purified by hot alkaline extraction. As a waste by-product red mud is formed. Due to its high alkalinity and large quantities, it represents a severe disposal problem. In Kidri?evo (Slovenia), red mud was washed with water before disposal, and after drying, covered with soil. In Ajka (Hungary), the red mud slurry was collected directly in a containment structure, which burst caused a major accident in October 2010. In the present work the environmental impact of toxic elements in red mud from Kidri?evo and Ajka were evaluated by applying a sequential extraction procedure and speciation analysis. The predominant red mud fraction was the insoluble residue; nevertheless, environmental concern was focused on the highly mobile water-soluble fraction of Al and Cr. Al in the water-soluble Ajka mud fraction was present exclusively in form of toxic [Al(OH)(4)](-), while Cr existed in its toxic hexavalent form. Comparative assessment to red mud from Kidri?evo (Slovenia) with a lower alkalinity (pH 9) with that from Ajka demonstrated significantly lower Al solubility and the presence of only trace amounts of Cr(VI), confirming that disposal of neutralized mud is environmentally much more acceptable and carries a smaller risk of ecological accidents. Since during the Ajka accident huge amounts of biologically available Al and moderate Cr(VI) concentrations were released into the terrestrial and aquatic environments, monitoring of Al and Cr(VI) set free during remedial actions at the contaminated site is essential. Particular care should be taken to minimize the risk of release of soluble Al species and Cr(VI) into water supplies and surface waters.","Environmental impact of toxic elements in red mud studied by fractionation and speciation procedures Abs: Aluminum (Al) is mostly produced from bauxite ore, which contains up to 70% of Al(2)O(3) (alumina). Before alumina is refined to aluminum metal, it is purified by hot alkaline extraction. As a waste by-product red mud is formed. Due to its high alkalinity and large quantities, it represents a severe disposal problem. In Kidri?evo (Slovenia), red mud was washed with water before disposal, and after drying, covered with soil. In Ajka (Hungary), the red mud slurry was collected directly in a containment structure, which burst caused a major accident in October 2010. In the present work the environmental impact of toxic elements in red mud from Kidri?evo and Ajka were evaluated by applying a sequential extraction procedure and speciation analysis. The predominant red mud fraction was the insoluble residue; nevertheless, environmental concern was focused on the highly mobile water-soluble fraction of Al and Cr. Al in the water-soluble Ajka mud fraction was present exclusively in form of toxic [Al(OH)(4)](-), while Cr existed in its toxic hexavalent form. Comparative assessment to red mud from Kidri?evo (Slovenia) with a lower alkalinity (pH 9) with that from Ajka demonstrated significantly lower Al solubility and the presence of only trace amounts of Cr(VI), confirming that disposal of neutralized mud is environmentally much more acceptable and carries a smaller risk of ecological accidents. Since during the Ajka accident huge amounts of biologically available Al and moderate Cr(VI) concentrations were released into the terrestrial and aquatic environments, monitoring of Al and Cr(VI) set free during remedial actions at the contaminated site is essential. Particular care should be taken to minimize the risk of release of soluble Al species and Cr(VI) into water supplies and surface waters."
1577648,Ghoulipour and  Husain 2002,Inorganic ion-exchangers for quantitative TLC of toxic elements. V. Separation and determination of chromium(VI),,Inorganic ion-exchangers for quantitative TLC of toxic elements. V. Separation and determination of chromium(VI) Abs: 
1577647,Gili et al. 2002,On the interaction of compounds of chromium(VI) with hydrogen peroxide. A study of chromium(VI) and (V) peroxides in the acid-basic pH range,,On the interaction of compounds of chromium(VI) with hydrogen peroxide. A study of chromium(VI) and (V) peroxides in the acid-basic pH range Abs: 
1577646,Gkika et al. 2006,Photocatalytic reduction of chromium and oxidation of organics by polyoxometalates,,Photocatalytic reduction of chromium and oxidation of organics by polyoxometalates Abs: 
1577645,Goncalves et al. 2011,"Changes in glucose uptake rate and in the energy status of PC-12 cells acutely exposed to hexavalent chromium, an established human carcinogen",,"Changes in glucose uptake rate and in the energy status of PC-12 cells acutely exposed to hexavalent chromium, an established human carcinogen Abs: "
1577644,Gondal et al. 2009,On-line monitoring of remediation process of chromium polluted soil using LIBS,"Due to large growth in leather and textile industries to cater for the needs of a growing world population, contamination of soil and water resources by chromium has become a great threat for humans and animals. In this work, Laser Induced Breakdown Spectroscopy (LIBS) was applied to monitor the remediation process of soil contaminated with Chromium metal. This study was conducted at a laboratory scale by setting up an experiment in a container holding soil contaminated with chromium. This setup represents actual field conditions where remediation process could be applied and monitored for the removal of toxic metals like Cr. For generation of LIBS spectrum, the plasma was produced by focusing a pulsed Nd: YAG laser at 1064 nm on the soil contaminated with chromium under remediation process. The evaluation of the potential and capabilities of LIBS as a rapid tool for remediation process of contaminated sites is discussed in detail. Optimal experimental conditions were evaluated for improving the sensitivity of our LIBS system for monitoring of remediation process through parametric dependence study. The minimum detection limit of our spectrometer for chromium in soil matrix was 2 mg Kg(-1).","On-line monitoring of remediation process of chromium polluted soil using LIBS Abs: Due to large growth in leather and textile industries to cater for the needs of a growing world population, contamination of soil and water resources by chromium has become a great threat for humans and animals. In this work, Laser Induced Breakdown Spectroscopy (LIBS) was applied to monitor the remediation process of soil contaminated with Chromium metal. This study was conducted at a laboratory scale by setting up an experiment in a container holding soil contaminated with chromium. This setup represents actual field conditions where remediation process could be applied and monitored for the removal of toxic metals like Cr. For generation of LIBS spectrum, the plasma was produced by focusing a pulsed Nd: YAG laser at 1064 nm on the soil contaminated with chromium under remediation process. The evaluation of the potential and capabilities of LIBS as a rapid tool for remediation process of contaminated sites is discussed in detail. Optimal experimental conditions were evaluated for improving the sensitivity of our LIBS system for monitoring of remediation process through parametric dependence study. The minimum detection limit of our spectrometer for chromium in soil matrix was 2 mg Kg(-1)."
1577643,Gorbi et al. 2004,"Bioavailability, bioaccumulation and tolerance of chromium: consequences in the food chain of freshwater ecosystems","Many abiotic and biotic factors can influence the partitioning equilibrium of heavy metals, thus influencing metal impact on aquatic environments. Unicellular algal species release soluble organic substances able to complex metals. In our laboratory a Cr-tolerant strain was selected and isolated from a wild type strain of Scenedesmus acutus. The exudates released by the two strains counteracted the growth inhibition caused by Cr(VI) and the exudates of the Cr-tolerant strain were more effective. On the contrary, the exudates did not reduce chromium toxicity to the cladoceran Daphnia magna. The reduction of chromium effect on algae seems the consequence of an algae-specific interaction among Cr(VI), exudates and algal cells. Chromium uptake resulted to be energy-dependent since bioaccumulation rate in subdued light condition was lower than at high light intensity. The effect of Cr(VI) on algae changed depending on metabolism of the cells and in particular it seemed to be related to the bioaccumulation rate. Tolerance in the selected strain could not be ascribed to a lower uptake of chromium. The difference in sensitivity to chromium between the two strains was exploited to evaluate if tolerance acquired by algae could have consequences for Daphnia. After treatment with Cr(VI), the two strains of S. acutus were used as food source for D. magna. The results indicate that chromium is accumulated by algae in a form not available for daphnids and that Cr tolerance acquired by the algae can be of some advantage to the consumer organism.","Bioavailability, bioaccumulation and tolerance of chromium: consequences in the food chain of freshwater ecosystems Abs: Many abiotic and biotic factors can influence the partitioning equilibrium of heavy metals, thus influencing metal impact on aquatic environments. Unicellular algal species release soluble organic substances able to complex metals. In our laboratory a Cr-tolerant strain was selected and isolated from a wild type strain of Scenedesmus acutus. The exudates released by the two strains counteracted the growth inhibition caused by Cr(VI) and the exudates of the Cr-tolerant strain were more effective. On the contrary, the exudates did not reduce chromium toxicity to the cladoceran Daphnia magna. The reduction of chromium effect on algae seems the consequence of an algae-specific interaction among Cr(VI), exudates and algal cells. Chromium uptake resulted to be energy-dependent since bioaccumulation rate in subdued light condition was lower than at high light intensity. The effect of Cr(VI) on algae changed depending on metabolism of the cells and in particular it seemed to be related to the bioaccumulation rate. Tolerance in the selected strain could not be ascribed to a lower uptake of chromium. The difference in sensitivity to chromium between the two strains was exploited to evaluate if tolerance acquired by algae could have consequences for Daphnia. After treatment with Cr(VI), the two strains of S. acutus were used as food source for D. magna. The results indicate that chromium is accumulated by algae in a form not available for daphnids and that Cr tolerance acquired by the algae can be of some advantage to the consumer organism."
1577642,Gikas and  Romanos 2006,Effects of tri-valent (Cr(III)) and hexa-valent (Cr(VI)) chromium on the growth of activated sludge,"The effects of Cr(VI) and Cr(III) species on the activated sludge growth rate have been assessed for a batch growth system, for a range of chromium concentration between 0 and 320 mg l(-1). Cr(VI) was found to stimulate microbial growth for concentrations up to about 25 mg l(-1), exhibiting maximum growth stimulation at 10 mg l(-1), whilst the lethal dose was found to be between 80 and 160 mg l(-1). On the other hand, Cr(III) was also found to stimulate microbial growth for concentrations up to about 15 mg l(-1), (with a maximum stimulation concentration at 10 mg l(-1)), whilst the lethal dose was found to lie between 160 and 320 mg l(-1). The results indicate that Cr(VI) is more toxic to biomass at relatively high concentrations (higher than 70 mg l(-1)) whilst it has a more pronounced growth stimulation effect at relatively smaller concentrations (less than 25 mg l(-1)), compared with Cr(III).","Effects of tri-valent (Cr(III)) and hexa-valent (Cr(VI)) chromium on the growth of activated sludge Abs: The effects of Cr(VI) and Cr(III) species on the activated sludge growth rate have been assessed for a batch growth system, for a range of chromium concentration between 0 and 320 mg l(-1). Cr(VI) was found to stimulate microbial growth for concentrations up to about 25 mg l(-1), exhibiting maximum growth stimulation at 10 mg l(-1), whilst the lethal dose was found to be between 80 and 160 mg l(-1). On the other hand, Cr(III) was also found to stimulate microbial growth for concentrations up to about 15 mg l(-1), (with a maximum stimulation concentration at 10 mg l(-1)), whilst the lethal dose was found to lie between 160 and 320 mg l(-1). The results indicate that Cr(VI) is more toxic to biomass at relatively high concentrations (higher than 70 mg l(-1)) whilst it has a more pronounced growth stimulation effect at relatively smaller concentrations (less than 25 mg l(-1)), compared with Cr(III)."
1577631,Ding et al. 1996,Elemental speciation for chromium in chromium picolinate products,,Elemental speciation for chromium in chromium picolinate products Abs: 
1577624,Ghosh et al. 2012,"Micellar Catalysis on 1,10-Phenanthroline Promoted Chromic Acid Oxidation of Glycerol in Aqueous Media",,"Micellar Catalysis on 1,10-Phenanthroline Promoted Chromic Acid Oxidation of Glycerol in Aqueous Media Abs: "
1577623,Ghosh et al. 2012,Micellar Catalysis on Pentavalent Vanadium Ion Oxidation of Ethanol in Aqueous Acid Media,,Micellar Catalysis on Pentavalent Vanadium Ion Oxidation of Ethanol in Aqueous Acid Media Abs: 
1577622,Ghosh et al. 2012,Micellar catalysis on picolinic acid promoted hexavalent chromium oxidation of glycerol,,Micellar catalysis on picolinic acid promoted hexavalent chromium oxidation of glycerol Abs: 
1577621,Ghosh et al. 2012,"Micellar catalysis of the 1,10-phenanthroline-promoted chromic acid oxidation of propan-2-ol in aqueous media",,"Micellar catalysis of the 1,10-phenanthroline-promoted chromic acid oxidation of propan-2-ol in aqueous media Abs: "
1577620,Gheju 2011,Hexavalent Chromium Reduction with Zero-Valent Iron (ZVI) in Aquatic Systems,,Hexavalent Chromium Reduction with Zero-Valent Iron (ZVI) in Aquatic Systems Abs: 
1577619,Ghazy and  Moustafa 2001,Flotation-separation of chromium(VI) and chromium(III) from water and leathers tanning waste using active charcoal and oleic acid surfactant,,Flotation-separation of chromium(VI) and chromium(III) from water and leathers tanning waste using active charcoal and oleic acid surfactant Abs: 
1577618,Ghazy et al. 2001,"Flotation-separation of the pollutant species of chromium, cadmium and lead from aqueous solutions and natural waters",,"Flotation-separation of the pollutant species of chromium, cadmium and lead from aqueous solutions and natural waters Abs: "
1577617,Gebrekidan et al. 2009,ENVIRONMENTAL IMPACTS OF SHEBA TANNERY (ETHIOPIA) EFFLUENTS ON THE SURROUNDING WATER BODIES,,ENVIRONMENTAL IMPACTS OF SHEBA TANNERY (ETHIOPIA) EFFLUENTS ON THE SURROUNDING WATER BODIES Abs: 
1577616,Gavilan Garcia et al. 2012,Policy options for the management of end of life computers in Mexico,,Policy options for the management of end of life computers in Mexico Abs: 
1577615,Ganguly et al. 2004,"Oxidative deprotection of oximes, phenylhydrazones and semicarbazones using pyridinium chlorochromate in catalytic amount with t-butyl hydroperoxide and in the solid state on montmorillonite K-10 clay support under microwave irradiation",,"Oxidative deprotection of oximes, phenylhydrazones and semicarbazones using pyridinium chlorochromate in catalytic amount with t-butyl hydroperoxide and in the solid state on montmorillonite K-10 clay support under microwave irradiation Abs: "
1577614,Frontasyeva et al. 2009,ACCUMULATION OF TRACE ELEMENTS BY BIOLOGICAL MATRICE OF Spirulina platensis,,ACCUMULATION OF TRACE ELEMENTS BY BIOLOGICAL MATRICE OF Spirulina platensis Abs: 
1577613,Fournier-Salaun and  Vauclair 2002,Recovery of chromique ions from aqueous effluents by liquid membrane in continuous mode,,Recovery of chromique ions from aqueous effluents by liquid membrane in continuous mode Abs: 
1577612,Fournier-Salauen and  Salauen 2009,Influence of operating parameters on chromic ions removal from aqueous solution by liquid membranes,,Influence of operating parameters on chromic ions removal from aqueous solution by liquid membranes Abs: 
1577611,Fandeur et al. 2009,XANES Evidence for Oxidation of Cr(III)) to Cr(VI) by Mn-Oxides in a Lateritic Regolith Developed on Serpentinized Ultramafic Rocks of New Caledonia,,XANES Evidence for Oxidation of Cr(III)) to Cr(VI) by Mn-Oxides in a Lateritic Regolith Developed on Serpentinized Ultramafic Rocks of New Caledonia Abs: 
1577610,Fytianos et al. 1997,Removal of Cr(VI) from aqueous and wastewater samples by fly ash,BIOSIS COPYRIGHT: BIOL ABS. Batch sorption experiments were conducted to investigate the removal of hexavalent chromium (Cr(VI)) from aqueous solutions and tannery wastewater samples by fly ash. The results showed that the optimum removal was accomplished at pH 2 with a contact time between fly ash and Cr(VI) solution of 2 hours. The isotherm data followed the Freundlich equation and resulted in comparable sorbed phase concentrations for both the aqueous and the tannery wastewater samples spiked with Cr(VI).,Removal of Cr(VI) from aqueous and wastewater samples by fly ash Abs: BIOSIS COPYRIGHT: BIOL ABS. Batch sorption experiments were conducted to investigate the removal of hexavalent chromium (Cr(VI)) from aqueous solutions and tannery wastewater samples by fly ash. The results showed that the optimum removal was accomplished at pH 2 with a contact time between fly ash and Cr(VI) solution of 2 hours. The isotherm data followed the Freundlich equation and resulted in comparable sorbed phase concentrations for both the aqueous and the tannery wastewater samples spiked with Cr(VI).
1577609,Fujie et al. 1996,Optimal operation of bioreactor system developed for the treatment of chromate wastewater using Enterobacter cloacae HO-1,"BIOSIS COPYRIGHT: BIOL ABS. The characteristics of a novel bioreactor system developed for the simultaneous treatment of toxic hexavalent chromium (chromate) and high-strength organic pollution by introducing a chromate-resistant and chromate-reducing bacterium Enterobacter cloacae strain HO-1 (HO-1, hereafter) were studied to optimize its operating condition. Based upon the growth and chromate-reducing kinetics of HO-1, a mathematical model to simulate the change of chromate removal rate per unit volume of bioreactor and that per unit cell mass under the fed-batch operation was proposed. The effects of repeated cultivation of HO-1 with ORP-controlled aeration and the cumulative chromate reduction per unit cell mass on the microbial activity were investigated to represent the kinetic expression of chromate reduction. By using the mathematical model developed through the present research, the relationship between the operating conditions and the chromate reduction rate in the bioreactor was simulat","Optimal operation of bioreactor system developed for the treatment of chromate wastewater using Enterobacter cloacae HO-1 Abs: BIOSIS COPYRIGHT: BIOL ABS. The characteristics of a novel bioreactor system developed for the simultaneous treatment of toxic hexavalent chromium (chromate) and high-strength organic pollution by introducing a chromate-resistant and chromate-reducing bacterium Enterobacter cloacae strain HO-1 (HO-1, hereafter) were studied to optimize its operating condition. Based upon the growth and chromate-reducing kinetics of HO-1, a mathematical model to simulate the change of chromate removal rate per unit volume of bioreactor and that per unit cell mass under the fed-batch operation was proposed. The effects of repeated cultivation of HO-1 with ORP-controlled aeration and the cumulative chromate reduction per unit cell mass on the microbial activity were investigated to represent the kinetic expression of chromate reduction. By using the mathematical model developed through the present research, the relationship between the operating conditions and the chromate reduction rate in the bioreactor was simulat"
1577608,Ezoddin et al. 2010,Application of mixed-micelle cloud point extraction for speciation analysis of chromium in water samples by electrothermal atomic absorption spectrometry,,Application of mixed-micelle cloud point extraction for speciation analysis of chromium in water samples by electrothermal atomic absorption spectrometry Abs: 
1577607,Everts 2007,Chromium cleanup,,Chromium cleanup Abs: 
1577604,Ershov et al. 1997,Evaluation of biological activity of toxic agents in a unicellular model,,Evaluation of biological activity of toxic agents in a unicellular model Abs: 
1577603,Erdem and  Tumen 2004,Chromium removal from aqueous solution by ferrite process,,Chromium removal from aqueous solution by ferrite process Abs: 
1577599,Elsayed and  Saba 2009,The Electrochemical Treatment of Toxic Hexavalent Chromium from Industrial Effluents using Rotating Cylinder Electrode Cell,,The Electrochemical Treatment of Toxic Hexavalent Chromium from Industrial Effluents using Rotating Cylinder Electrode Cell Abs: 
1577596,Eid et al. 1996,Characterization and treatment of the soil of an industrial site contaminated with chromium(VI),"The surface and soil of an industrial site, which was used for 80 years to manufacture porcelain enamel signs for California highways, was characterized to determine any contamination due to toxic metals. Although surface concrete samples showed hazardous concentrations of lead, cadmium, nickel and zinc, the soil samples were found to be free of any contamination for these metals. However, soil samples collected at certain depths from certain locations were found to contain hazardous concentrations of both total chromium and hexavalent chromium. These chromium concentrations were found to vary with depth, maximizing at 20 ft and decreasing below that. Total volume of the contaminated soil was estimated and a soil treatment process which involves reduction of Cr(VI) to Cr(III) using meta bisulfate as the treatment reagent was developed in the laboratory, and then tried on contaminated soil samples. Greater than 90% reduction of Cr(VI) to Cr(III) was observed. The treatment process developed was then used to design a remedial action plan for on-site treatment of the contaminated soil.","Characterization and treatment of the soil of an industrial site contaminated with chromium(VI) Abs: The surface and soil of an industrial site, which was used for 80 years to manufacture porcelain enamel signs for California highways, was characterized to determine any contamination due to toxic metals. Although surface concrete samples showed hazardous concentrations of lead, cadmium, nickel and zinc, the soil samples were found to be free of any contamination for these metals. However, soil samples collected at certain depths from certain locations were found to contain hazardous concentrations of both total chromium and hexavalent chromium. These chromium concentrations were found to vary with depth, maximizing at 20 ft and decreasing below that. Total volume of the contaminated soil was estimated and a soil treatment process which involves reduction of Cr(VI) to Cr(III) using meta bisulfate as the treatment reagent was developed in the laboratory, and then tried on contaminated soil samples. Greater than 90% reduction of Cr(VI) to Cr(III) was observed. The treatment process developed was then used to design a remedial action plan for on-site treatment of the contaminated soil."
1577595,Earley et al. 2009,Remediation of chromium(VI) at polypyrrole-coated titanium,,Remediation of chromium(VI) at polypyrrole-coated titanium Abs: 
1577593,Dudek and  Wetterhahn 1994,"ANALYSIS OF STEADY-STATE MESSENGER-RNA LEVELS OF CATALASE AND HEME OXYGENASE IN CULTURED RAT FAO CELLS TREATED WITH CHROMIUM(VI), USING SOLUTION HYBRIDIZATION","A sensitive solution hybridization assay was used to quantitate changes in the steady-state mRNA levels of two oxidative damage-inducible genes, catalase and heme oxygenase, in rat FAO cells treated with sodium dichromate [Cr(VI)], and two known oxidant compounds, hydrogen peroxide and heme. Both catalase and heme oxygenase mRNA levels were observed to be increased in cell cultures after a 4 h treatment with 5 muM Cr(VI). Catalase steady-state mRNA levels were induced approximately 4-fold while heme oxygenase mRNA levels were induced about 2-fold above basal expression. In comparison, treatment of FAO cell cultures with 200 muM hydrogen peroxide, a reactive intracellular oxidant, increased catalase mRNA levels 2-fold after 4 h of exposure. Induction of heme oxygenase for 8 h with 5 muM heme, an Fe(II)-containing natural inducer for this gene, was similar to Cr(VI) induction. Since the intracellular reduction of Cr(VI) to Cr(III) is believed to produce reactive intermediates, catalase and heme oxygenase induction in FAO cells by Cr(VI) may occur in response to an increase in cellular oxidative damage. The nature of Cr(VI)-mediated induction of oxidative damage-inducible gene expression and a detailed description of the solution hybridization assay is presented.","ANALYSIS OF STEADY-STATE MESSENGER-RNA LEVELS OF CATALASE AND HEME OXYGENASE IN CULTURED RAT FAO CELLS TREATED WITH CHROMIUM(VI), USING SOLUTION HYBRIDIZATION Abs: A sensitive solution hybridization assay was used to quantitate changes in the steady-state mRNA levels of two oxidative damage-inducible genes, catalase and heme oxygenase, in rat FAO cells treated with sodium dichromate [Cr(VI)], and two known oxidant compounds, hydrogen peroxide and heme. Both catalase and heme oxygenase mRNA levels were observed to be increased in cell cultures after a 4 h treatment with 5 muM Cr(VI). Catalase steady-state mRNA levels were induced approximately 4-fold while heme oxygenase mRNA levels were induced about 2-fold above basal expression. In comparison, treatment of FAO cell cultures with 200 muM hydrogen peroxide, a reactive intracellular oxidant, increased catalase mRNA levels 2-fold after 4 h of exposure. Induction of heme oxygenase for 8 h with 5 muM heme, an Fe(II)-containing natural inducer for this gene, was similar to Cr(VI) induction. Since the intracellular reduction of Cr(VI) to Cr(III) is believed to produce reactive intermediates, catalase and heme oxygenase induction in FAO cells by Cr(VI) may occur in response to an increase in cellular oxidative damage. The nature of Cr(VI)-mediated induction of oxidative damage-inducible gene expression and a detailed description of the solution hybridization assay is presented."
1577588,Dubbin and  Goh 1999,Permanganate-mediated dissolution of hydroxy-Cr interlayers from montmorillonite,,Permanganate-mediated dissolution of hydroxy-Cr interlayers from montmorillonite Abs: 
1577587,Du et al. 2012,Cr(VI) retention and transport through Fe(III)-coated natural zeolite,,Cr(VI) retention and transport through Fe(III)-coated natural zeolite Abs: 
1577586,Doyle et al. 2004,Inhibition of the reduction of Cr(VI) at the magnetite-water interface by calcium carbonate coatings,,Inhibition of the reduction of Cr(VI) at the magnetite-water interface by calcium carbonate coatings Abs: 
1577585,Dlugosz et al. 2012,Influence of Chromium on the Natural Antioxidant Barrier,,Influence of Chromium on the Natural Antioxidant Barrier Abs: 
1577584,Djurendic et al. 2012,"Synthesis, X-ray structural analysis, and cytotoxic activity of some new androstane D-homo lactone derivatives",,"Synthesis, X-ray structural analysis, and cytotoxic activity of some new androstane D-homo lactone derivatives Abs: "
1577583,Djouider and  Aljohani 2010,Application of ionizing radiation to environmental protection: removal of toxic Cr(VI) metal ion in industrial wastewater: preliminary study,,Application of ionizing radiation to environmental protection: removal of toxic Cr(VI) metal ion in industrial wastewater: preliminary study Abs: 
1577582,Dinis et al. 2012,EFFECT OF Cr(VI) IN FOUR PORTUGUESE MICROALGAE GROWTH,,EFFECT OF Cr(VI) IN FOUR PORTUGUESE MICROALGAE GROWTH Abs: 
1577581,Din et al. 2001,Effect of cationic and anionic micelles on the one-step three-electron oxidation of lactic acid by HCrO4- in the presence and absence of manganese (II),,Effect of cationic and anionic micelles on the one-step three-electron oxidation of lactic acid by HCrO4- in the presence and absence of manganese (II) Abs: 
1577580,D'ors et al. 2010,Toxic effects and specific chromium acquired resistance in selected strains of Dyctiosphaerium chlorelloides,"Due to its various uses, chromium contamination has become widespread in a diverse array of environments. The present study was carried out to investigate the toxic effect of chromium exposures on sensitive and resistant strains of the green algae Dyctiosphaerium chlorelloides, and to determine the nature and mechanism of chromium-resistant cells that arise. The toxic effect on the photosynthetic performance of chromium exposures in both cell populations, and the sensitive differences due to chromium oxidation state, were estimated, and the results indicate that although the photosynthetic performance in both strains were inhibited, there are not significant differences among IC(50(72)) values obtained in toxicity assays with both chromium oxidation states in wild-type cells, and however these differences are very significant when the assays were performed with Cr(VI) resistant cells. The 72-h 50% inhibitory concentration values obtained with Cr(III) exposures were similar for both strains. Additionally, by means of the SEM/EDX and TEM microscopic techniques, the occurrence of rapid morphological evolution in the microalgal cells and the possible detoxificant mechanisms was observed after exposure of the wild strain to chromium hexavalent. Moreover, the different response in photosynthetic activity observed between sensitive and resistant cells of D. chlorelloides in the presence of Cr(VI) and Cr(III) could be used to obtain a chromium-specific eukaryotic microalgal biosensor.","Toxic effects and specific chromium acquired resistance in selected strains of Dyctiosphaerium chlorelloides Abs: Due to its various uses, chromium contamination has become widespread in a diverse array of environments. The present study was carried out to investigate the toxic effect of chromium exposures on sensitive and resistant strains of the green algae Dyctiosphaerium chlorelloides, and to determine the nature and mechanism of chromium-resistant cells that arise. The toxic effect on the photosynthetic performance of chromium exposures in both cell populations, and the sensitive differences due to chromium oxidation state, were estimated, and the results indicate that although the photosynthetic performance in both strains were inhibited, there are not significant differences among IC(50(72)) values obtained in toxicity assays with both chromium oxidation states in wild-type cells, and however these differences are very significant when the assays were performed with Cr(VI) resistant cells. The 72-h 50% inhibitory concentration values obtained with Cr(III) exposures were similar for both strains. Additionally, by means of the SEM/EDX and TEM microscopic techniques, the occurrence of rapid morphological evolution in the microalgal cells and the possible detoxificant mechanisms was observed after exposure of the wild strain to chromium hexavalent. Moreover, the different response in photosynthetic activity observed between sensitive and resistant cells of D. chlorelloides in the presence of Cr(VI) and Cr(III) could be used to obtain a chromium-specific eukaryotic microalgal biosensor."
1577579,Donais et al. 1999,Chromium speciation using an automated liquid handling system with inductively coupled plasma - mass spectrometric detection,"The speciation of inorganic chromium in environmental samples is required for accurate assessment of pollution levels. Of the two chromium oxidation states, Cr (VI) is a known carcinogen, while Cr (III) is an essential element. Total chromium measurement cannot be used to determine actual environmental impact due to the considerable difference in toxicity of the two elemental forms. An automated liquid handling system, the PrepLabtrade mark, can be used with an inductively coupled plasma-mass spectrometer (ICP-MS) to quantify Cr (III) and Cr (VI) in liquid samples. An autosampler is used to introduce discrete sample volumes into a solid-phase chelation resin column. The Cr (III) and Cr (VI) species are separated and are introduced on-line into the VG PlasmaQuad 3 ICP-MS for detection. The chromatographic data are collected in time resolved analysis mode with the capability of simultaneous multiple-isotopic detection.","Chromium speciation using an automated liquid handling system with inductively coupled plasma - mass spectrometric detection Abs: The speciation of inorganic chromium in environmental samples is required for accurate assessment of pollution levels. Of the two chromium oxidation states, Cr (VI) is a known carcinogen, while Cr (III) is an essential element. Total chromium measurement cannot be used to determine actual environmental impact due to the considerable difference in toxicity of the two elemental forms. An automated liquid handling system, the PrepLabtrade mark, can be used with an inductively coupled plasma-mass spectrometer (ICP-MS) to quantify Cr (III) and Cr (VI) in liquid samples. An autosampler is used to introduce discrete sample volumes into a solid-phase chelation resin column. The Cr (III) and Cr (VI) species are separated and are introduced on-line into the VG PlasmaQuad 3 ICP-MS for detection. The chromatographic data are collected in time resolved analysis mode with the capability of simultaneous multiple-isotopic detection."
1577578,Dillon et al. 2000,DNA interactions and bacterial mutagenicity of some chromium(III) imine complexes and their chromium(V) analogues. Evidence for chromium(V) intermediates in the genotoxicity of chromium(III),,DNA interactions and bacterial mutagenicity of some chromium(III) imine complexes and their chromium(V) analogues. Evidence for chromium(V) intermediates in the genotoxicity of chromium(III) Abs: 
1577577,Diaconu et al. 2012,Kinetic Aspects of Transport para-aminophenol through Agitated Bulk Liquid Membrane,,Kinetic Aspects of Transport para-aminophenol through Agitated Bulk Liquid Membrane Abs: 
1577576,Dhakate et al. 2008,"Impact assessment of chromite mining on groundwater through simulation modeling study in Sukinda chromite mining area, Orissa, India",,"Impact assessment of chromite mining on groundwater through simulation modeling study in Sukinda chromite mining area, Orissa, India Abs: "
1577575,Dey et al. 2003,Alpha-tocopherol supplementation on chromium toxicity: a study on rat liver and kidney cell membrane,,Alpha-tocopherol supplementation on chromium toxicity: a study on rat liver and kidney cell membrane Abs: 
1577574,Dey et al. 2001,Chromium-induced membrane damage: protective role of ascorbic acid,,Chromium-induced membrane damage: protective role of ascorbic acid Abs: 
1577573,Dermatas and  Moon 2006,Chromium leaching and immobilization in treated soils,,Chromium leaching and immobilization in treated soils Abs: 
1577572,Deng et al. 2012,Application of Porous N-Methylimidazolium Strongly Basic Anion Exchange Resins on Cr(VI) Adsorption from Electroplating Wastewater,,Application of Porous N-Methylimidazolium Strongly Basic Anion Exchange Resins on Cr(VI) Adsorption from Electroplating Wastewater Abs: 
1577571,Deng and  Ting 2005,Polyethylenimine-modified fungal biomass as a high-capacity biosorbent for Cr(VI) anions: Sorption capacity and uptake mechisms,,Polyethylenimine-modified fungal biomass as a high-capacity biosorbent for Cr(VI) anions: Sorption capacity and uptake mechisms Abs: 
1577569,Demir et al. 2010,ANTIGENOTOXIC PROPERTIES OF CHLOROPHYLLIN AND CHLOROPHYLLS IN THE DROSOPHILA WING SPOT TEST,,ANTIGENOTOXIC PROPERTIES OF CHLOROPHYLLIN AND CHLOROPHYLLS IN THE DROSOPHILA WING SPOT TEST Abs: 
1577568,Demir 2012,INVESTIGATION OF THE EFFECTS OF COBALT CHLORIDE AND POTASSIUM DICHROMATE ON THE GENOTOXIC ACTIVITY AND THE LONGEVITY OF DROSOPHILA MELANOGASTER,,INVESTIGATION OF THE EFFECTS OF COBALT CHLORIDE AND POTASSIUM DICHROMATE ON THE GENOTOXIC ACTIVITY AND THE LONGEVITY OF DROSOPHILA MELANOGASTER Abs: 
1577567,Demidova et al. 2008,Generation of silver and lead chromate nanoparticles in Triton N-42 and AOT reversed-micellar solutions,,Generation of silver and lead chromate nanoparticles in Triton N-42 and AOT reversed-micellar solutions Abs: 
1577566,de Oliveira et al. 2010,Direct chromium speciation using X-ray spectrometry and chemometrics,,Direct chromium speciation using X-ray spectrometry and chemometrics Abs: 
1577565,Das et al. 2010,Combined effects of sugarcane bagasse extract and synthetic dyes on the growth and bioaccumulation properties of Pichia fermentans MTCC 189,,Combined effects of sugarcane bagasse extract and synthetic dyes on the growth and bioaccumulation properties of Pichia fermentans MTCC 189 Abs: 
1577563,Deepa et al. 2006,Sorption of Cr(VI) from dilute solutions and wastewater by live and pretreated biomass of Aspergillus flavus,"Sorption of Cr(VI) was carried out from dilute solutions using live and pretreated biomass in a batch mode. Effects of agitation time, adsorbent dosage and pH were examined. The autoclaved biomass that showed maximum adsorption capacity (Q(0)=0.335 mg g(-1)) was used as an adsorbent in column studies. The optimized flow rate of 2.5 ml min(-1) and bed height 10 cm were used to determine the effect of metal ion concentration on removal of Cr(VI). Applying the BDST model to calculate the adsorption capacity (N(0)) of column, which showed 4.56 x 10(-5), 7.28 x 10(-5), 6.89 x 10(-5), 3.07 x 10(-5), 2.80 x 10(-5)mg g(-1) for 4, 8, 12, 16 and 20 mg dm(-3) of Cr(VI), respectively. Batch sorption proved to be more efficient than the column sorption and hence batch sorption was used to remove Cr(VI) from a textile dyeing industry wastewater. The phytotoxic effect of treated and untreated wastewater was studied against Zea mays. Toxicity was reduced by 50% in the treated effluent.","Sorption of Cr(VI) from dilute solutions and wastewater by live and pretreated biomass of Aspergillus flavus Abs: Sorption of Cr(VI) was carried out from dilute solutions using live and pretreated biomass in a batch mode. Effects of agitation time, adsorbent dosage and pH were examined. The autoclaved biomass that showed maximum adsorption capacity (Q(0)=0.335 mg g(-1)) was used as an adsorbent in column studies. The optimized flow rate of 2.5 ml min(-1) and bed height 10 cm were used to determine the effect of metal ion concentration on removal of Cr(VI). Applying the BDST model to calculate the adsorption capacity (N(0)) of column, which showed 4.56 x 10(-5), 7.28 x 10(-5), 6.89 x 10(-5), 3.07 x 10(-5), 2.80 x 10(-5)mg g(-1) for 4, 8, 12, 16 and 20 mg dm(-3) of Cr(VI), respectively. Batch sorption proved to be more efficient than the column sorption and hence batch sorption was used to remove Cr(VI) from a textile dyeing industry wastewater. The phytotoxic effect of treated and untreated wastewater was studied against Zea mays. Toxicity was reduced by 50% in the treated effluent."
1577562,de la Rosa et al. 2003,Utilization of ICP/OES for the determination of trace metal binding to different humic fractions,"In this study, the use of inductively coupled plasma/optical emission spectrometry (ICP/OES) to determine multi-metal binding to three biomasses, Sphagnum peat moss, humin and humic acids is reported. All the investigations were performed under part per billion (ppb) concentrations. Batch pH profile experiments were performed using multi-metal solutions of Cd(II), Cu(II), Pb(II), Ni(II), Cr(III) and Cr(VI). The results showed that at pH 2 and 3, the metal affinity of the three biomasses exposed to the multi-metal solution that included Cr(III) presented the following order: Cu(II), Pb(II)&gt;Ni(II)&gt;Cr(III)&gt;Cd(II). On the other hand, when Cr(VI) was in the heavy metal mixture, Sphagnum peat moss and humin showed the following affinity: Cu(II), Pb(II)&gt;Ni(II)&gt;Cr(VI)&gt;Cd(II); however, the affinity of the humic acids was: Cu(II)&gt;Pb(II), Cr(VI)&gt;Ni(II)&gt;Cd(II). The results demonstrated that pH values of 4 and 5 were the most favorable for the heavy metal binding process. At pH 5, all the metals, except for Cr(VI), were bound between 90 and 100% to the three biomasses. However, the binding capacity of humic acids decreased at pH 6 in the presence of Cr(VI). The results showed that the ICP/OES permits the determination of heavy metal binding to organic matter at ppb concentration. These results will be very useful in understanding the role of humic substances in the fate and transport of heavy metals, and thus could provide information to develop new methodologies for the removal of low concentrations of toxic heavy metals from contaminated waters.","Utilization of ICP/OES for the determination of trace metal binding to different humic fractions Abs: In this study, the use of inductively coupled plasma/optical emission spectrometry (ICP/OES) to determine multi-metal binding to three biomasses, Sphagnum peat moss, humin and humic acids is reported. All the investigations were performed under part per billion (ppb) concentrations. Batch pH profile experiments were performed using multi-metal solutions of Cd(II), Cu(II), Pb(II), Ni(II), Cr(III) and Cr(VI). The results showed that at pH 2 and 3, the metal affinity of the three biomasses exposed to the multi-metal solution that included Cr(III) presented the following order: Cu(II), Pb(II)&gt;Ni(II)&gt;Cr(III)&gt;Cd(II). On the other hand, when Cr(VI) was in the heavy metal mixture, Sphagnum peat moss and humin showed the following affinity: Cu(II), Pb(II)&gt;Ni(II)&gt;Cr(VI)&gt;Cd(II); however, the affinity of the humic acids was: Cu(II)&gt;Pb(II), Cr(VI)&gt;Ni(II)&gt;Cd(II). The results demonstrated that pH values of 4 and 5 were the most favorable for the heavy metal binding process. At pH 5, all the metals, except for Cr(VI), were bound between 90 and 100% to the three biomasses. However, the binding capacity of humic acids decreased at pH 6 in the presence of Cr(VI). The results showed that the ICP/OES permits the determination of heavy metal binding to organic matter at ppb concentration. These results will be very useful in understanding the role of humic substances in the fate and transport of heavy metals, and thus could provide information to develop new methodologies for the removal of low concentrations of toxic heavy metals from contaminated waters."
1577561,Das et al. 2001,Micellar effect on the reaction of chromium(VI) oxidation of D-fructose in the presence and absence of picolinic acid in aqueous media: a kinetic study,,Micellar effect on the reaction of chromium(VI) oxidation of D-fructose in the presence and absence of picolinic acid in aqueous media: a kinetic study Abs: 
1577560,Das et al. 2001,"Kinetics and mechanism of the picolinic acid catalysed chromium(VI) oxidation of ethane-1,2-diol in the presence and absence of surfactants",,"Kinetics and mechanism of the picolinic acid catalysed chromium(VI) oxidation of ethane-1,2-diol in the presence and absence of surfactants Abs: "
1577559,Das et al. 2001,Micellar effect on chromium(VI) oxidation of ethanol and propan-1-ol in aqueous acid media,,Micellar effect on chromium(VI) oxidation of ethanol and propan-1-ol in aqueous acid media Abs: 
1577558,Das et al. 2001,Micellar effect: evidence in favour of different mechanistic paths of chromium(VI) oxidation of formic acid and oxalic acid in aqueous acid media,,Micellar effect: evidence in favour of different mechanistic paths of chromium(VI) oxidation of formic acid and oxalic acid in aqueous acid media Abs: 
1577557,Das et al. 2001,Micellar effect on the reaction of picolinic acid catalyzed chromium(VI) oxidation of dimethyl sulfoxide in aqueous acidic media: A kinetic study,,Micellar effect on the reaction of picolinic acid catalyzed chromium(VI) oxidation of dimethyl sulfoxide in aqueous acidic media: A kinetic study Abs: 
1577556,Das et al. 2001,Micellar effect on chromium(VI) oxidation of D-glucose in the presence and absence of picolinic acid in aqueous media: A kinetic study,,Micellar effect on chromium(VI) oxidation of D-glucose in the presence and absence of picolinic acid in aqueous media: A kinetic study Abs: 
1577555,Das et al. 2001,Micellar effects on mechanistic paths of chromium(VI) oxidation of butan-2-ol and benzyl alcohol in aqueous acid media,,Micellar effects on mechanistic paths of chromium(VI) oxidation of butan-2-ol and benzyl alcohol in aqueous acid media Abs: 
1577554,Das et al. 2010,KINETIC AND MECHANISTIC ASPECTS OF THE CHROMIC ACID OXIDATION OF D-GALACTOSE IN THE PRESENCE AND ABSENCE OF PICOLINIC ACID CATALYST IN AQUEOUS MICELLAR ACID MEDIA,,KINETIC AND MECHANISTIC ASPECTS OF THE CHROMIC ACID OXIDATION OF D-GALACTOSE IN THE PRESENCE AND ABSENCE OF PICOLINIC ACID CATALYST IN AQUEOUS MICELLAR ACID MEDIA Abs: 
1577553,Cvijovic et al. 2010,A CASE STUDY OF INDUSTRIAL WATER POLLUTED WITH CHROMIUM (VI) AND ITS IMPACT TO RIVER RECIPIENT IN WESTERN SERBIA,,A CASE STUDY OF INDUSTRIAL WATER POLLUTED WITH CHROMIUM (VI) AND ITS IMPACT TO RIVER RECIPIENT IN WESTERN SERBIA Abs: 
1577550,Creelman et al. 1994,INTERMEDIA TRANSFER-FACTORS FOR MODELING THE ENVIRONMENTAL-IMPACT OF AIR-POLLUTION FROM INDUSTRIAL SOURCES,,INTERMEDIA TRANSFER-FACTORS FOR MODELING THE ENVIRONMENTAL-IMPACT OF AIR-POLLUTION FROM INDUSTRIAL SOURCES Abs: 
1577549,Cotman et al. 2003,An interlaboratory study to improve the quality of chemical and biological measurements in waste water,,An interlaboratory study to improve the quality of chemical and biological measurements in waste water Abs: 
1577548,Corradi et al. 1998,Exudates from the wild type and a Cr-tolerant strain of Scenedesmus acutus influence differently Cr(VI) toxicity to algae,,Exudates from the wild type and a Cr-tolerant strain of Scenedesmus acutus influence differently Cr(VI) toxicity to algae Abs: 
1577547,Corradi et al. 1993,CHROMIUM TOXICITY IN SALVIA-SCLAREA .1. EFFECTS OF HEXAVALENT CHROMIUM ON SEED-GERMINATION AND SEEDLING DEVELOPMENT,,CHROMIUM TOXICITY IN SALVIA-SCLAREA .1. EFFECTS OF HEXAVALENT CHROMIUM ON SEED-GERMINATION AND SEEDLING DEVELOPMENT Abs: 
1577546,Cordoves et al. 2008,Characterization of the binding site affinity distribution of a surfactant-modified clinoptilolite,,Characterization of the binding site affinity distribution of a surfactant-modified clinoptilolite Abs: 
1577545,Codd et al. 2000,Characterization and X-ray absorption spectroscopic studies of bis[quinato(2-)]oxochromate(V),,Characterization and X-ray absorption spectroscopic studies of bis[quinato(2-)]oxochromate(V) Abs: 
1577543,Cohen and  Petrie 2005,The application of batch extraction tests for the characterisation of solidified ferro alloy waste products,"Leach testing is arguably the best indicator of the effectiveness of pre-landfill treatments, including solidification/stabilisation (S/S), in reducing mobility of waste constituents. The results of leach tests can, however, also be interpreted to provide an understanding of the mechanisms via which toxic species are retained in the S/S product. An understanding of retention mechanisms contributes to the development of improved waste treatment systems. In this paper, we explore the applicability of four extraction tests, Pore Solution Expressions, the TCLP, the Equilibrium Extraction (EE) and the Sequential Chemical Extraction (SCE) for providing a description of the mechanisms of containment within an S/S product. The waste materials explored here are ferrochrome dusts with high levels of metals including Cr and Zn. The errors in results from the pore solution expressions and sequential chemical extractions were too high to draw any quantitative conclusions, although some qualitative comments could be made. The latter observations, however, were consistent with those from the other two tests, and together these build a comprehensive picture of the S/S products. For these specific products, it is suggested that a small amount (approximately 1%) of the Cr is Cr(VI) which is readily mobile, approximately 5% is Cr(III) which is mobile under acidic conditions and the remainder is a stabile chromite which is not readily mobile. For Zn, however, roughly equal proportions are contained as a species (possibly Zn(OH)2) whose release is pH dependent, and as a stable, immobile species on the surface of the dust particles.","The application of batch extraction tests for the characterisation of solidified ferro alloy waste products Abs: Leach testing is arguably the best indicator of the effectiveness of pre-landfill treatments, including solidification/stabilisation (S/S), in reducing mobility of waste constituents. The results of leach tests can, however, also be interpreted to provide an understanding of the mechanisms via which toxic species are retained in the S/S product. An understanding of retention mechanisms contributes to the development of improved waste treatment systems. In this paper, we explore the applicability of four extraction tests, Pore Solution Expressions, the TCLP, the Equilibrium Extraction (EE) and the Sequential Chemical Extraction (SCE) for providing a description of the mechanisms of containment within an S/S product. The waste materials explored here are ferrochrome dusts with high levels of metals including Cr and Zn. The errors in results from the pore solution expressions and sequential chemical extractions were too high to draw any quantitative conclusions, although some qualitative comments could be made. The latter observations, however, were consistent with those from the other two tests, and together these build a comprehensive picture of the S/S products. For these specific products, it is suggested that a small amount (approximately 1%) of the Cr is Cr(VI) which is readily mobile, approximately 5% is Cr(III) which is mobile under acidic conditions and the remainder is a stabile chromite which is not readily mobile. For Zn, however, roughly equal proportions are contained as a species (possibly Zn(OH)2) whose release is pH dependent, and as a stable, immobile species on the surface of the dust particles."
1577542,Codd et al. 1997,Stability and ligand exchange reactions of chromium(IV) carboxylato complexes in aqueous solutions,,Stability and ligand exchange reactions of chromium(IV) carboxylato complexes in aqueous solutions Abs: 
1577541,Codd and  Lay 1999,"Competition between 1,2-diol and 2-hydroxy acid coordination in Cr(V)-quinic acid complexes: Implications for stabilization of Cr(V) intermediates of relevance to Cr(VI)-induced carcinogenesis",,"Competition between 1,2-diol and 2-hydroxy acid coordination in Cr(V)-quinic acid complexes: Implications for stabilization of Cr(V) intermediates of relevance to Cr(VI)-induced carcinogenesis Abs: "
1577540,Cimino et al. 2000,Removal of toxic cations and Cr(Vi) from aqueous solution by hazelnut shell,,Removal of toxic cations and Cr(Vi) from aqueous solution by hazelnut shell Abs: 
1577539,Cieslak-Golonka et al. 2001,Systems containing carcinogenic CrO3 and cellular reductants. Thermal and spectroscopic investigation,,Systems containing carcinogenic CrO3 and cellular reductants. Thermal and spectroscopic investigation Abs: 
1577538,Chung et al. 2010,Integration of H-2-Based Membrane Biofilm Reactor with RO and NF Membranes for Removal of Chromate and Selenate,,Integration of H-2-Based Membrane Biofilm Reactor with RO and NF Membranes for Removal of Chromate and Selenate Abs: 
1577537,Chowdhury et al. 2009,"Micellar catalysis of chromium(VI) oxidation of ethane-1,2-diol in the presence and absence of 2,2'-bipyridine in aqueous acid media",,"Micellar catalysis of chromium(VI) oxidation of ethane-1,2-diol in the presence and absence of 2,2'-bipyridine in aqueous acid media Abs: "
1577536,Chico et al. 2008,Anticorrosive behaviour of alkyd paints formulated with ion-exchange pigments,"Hexavalent chromium compounds (chromates) have been widely used as inhibitive pigments in the formulation of anticorrosive paints. However, their high toxicity and carcinogenic effects are forcing the development of effective chromate-free organic coatings. One such alternative, which is very attractive from a scientific point of view, is the use of ion-exchangeable pigments (IEPs). The few studies conducted with this type of pigment are not conclusive about their anticorrosive efficiency and controversy surrounds their functioning mechanisms, interchange capacity and anticorrosive performance. In the present research, which focuses on the anticorrosive protection of this type of pigment, alkyd paint coatings formulated with vanadate-hydrotalcite (HT/V) (anionic) and calcium/silica (Ca/Si) (cationic) IEPs have been applied on low carbon steel specimens. A tradidonal zinc chromate pigment has also been used for comparative purposes. The effect of these non-toxic pigments on the protective properties of coatings has been tested by means of natural and accelerated corrosion tests (humidity, salt spray and Kesternich, 0.21 SO2) and electrochemical impedance spectroscopy (EIS). None of the IEPs equalled the anticorrosive behaviour of the zinc chromate in the different tests. The anionic pigment (HT/V) seems to present good behaviour in chloride environments (salt spray, NaCl solutions, etc.) while the cationic pigment (Ca/Si) performs well in the humidity condensation and SO2 tests. (C) 2007 Elsevier B.V. All rights reserved.","Anticorrosive behaviour of alkyd paints formulated with ion-exchange pigments Abs: Hexavalent chromium compounds (chromates) have been widely used as inhibitive pigments in the formulation of anticorrosive paints. However, their high toxicity and carcinogenic effects are forcing the development of effective chromate-free organic coatings. One such alternative, which is very attractive from a scientific point of view, is the use of ion-exchangeable pigments (IEPs). The few studies conducted with this type of pigment are not conclusive about their anticorrosive efficiency and controversy surrounds their functioning mechanisms, interchange capacity and anticorrosive performance. In the present research, which focuses on the anticorrosive protection of this type of pigment, alkyd paint coatings formulated with vanadate-hydrotalcite (HT/V) (anionic) and calcium/silica (Ca/Si) (cationic) IEPs have been applied on low carbon steel specimens. A tradidonal zinc chromate pigment has also been used for comparative purposes. The effect of these non-toxic pigments on the protective properties of coatings has been tested by means of natural and accelerated corrosion tests (humidity, salt spray and Kesternich, 0.21 SO2) and electrochemical impedance spectroscopy (EIS). None of the IEPs equalled the anticorrosive behaviour of the zinc chromate in the different tests. The anionic pigment (HT/V) seems to present good behaviour in chloride environments (salt spray, NaCl solutions, etc.) while the cationic pigment (Ca/Si) performs well in the humidity condensation and SO2 tests. (C) 2007 Elsevier B.V. All rights reserved."
1577535,Cheung et al. 2007,Mechanism of hexavalent chromium detoxification by microorganisms and bioremediation application potential: A review,,Mechanism of hexavalent chromium detoxification by microorganisms and bioremediation application potential: A review Abs: 
1577534,Chen et al. 2011,Influence of chemical compositions and molecular weights of humic acids on Cr(VI) photo-reduction,"Humic acids (HA) strongly affect the fate of trace metals in soils and aquatic environments. One of the remarkable properties of HA is its ability to reduce Cr(VI), an extremely toxic anion. However, it is unclear which HA components are involved in Cr(VI) reduction and possess the photo-induced properties. In this study, an ultrafiltration technique was used to fractionate HAs into four fractions of different nominal molecular weights (M(w)): &gt;100, 50-100, 10-50 and &lt;10 kDa. Each HA fraction was characterized by spectroscopic analyses followed by examining Cr(VI) removal on each fraction of HA at pH 1-5. Spectroscopic results indicated that low-M(w) HA was enriched with polar and aromatic domains. These polar, including polar C in aliphatic region, and aromatic groups were the major sites for Cr(VI) reduction because they disappeared rapidly upon interaction with Cr(VI). As a result, low M(w) of HA exhibited greater efficiency of Cr(VI) reduction. Light induced the rapid transfer of electrons between chromate-phenol/carboxyl ester, or the formation of peroxide radicals or H(2)O(2) through the ready decay of peroxy radicals associated with polar substituents, explained the rapid scavenging of Cr(VI) on polar and aromatic groups of HAs under illumination.","Influence of chemical compositions and molecular weights of humic acids on Cr(VI) photo-reduction Abs: Humic acids (HA) strongly affect the fate of trace metals in soils and aquatic environments. One of the remarkable properties of HA is its ability to reduce Cr(VI), an extremely toxic anion. However, it is unclear which HA components are involved in Cr(VI) reduction and possess the photo-induced properties. In this study, an ultrafiltration technique was used to fractionate HAs into four fractions of different nominal molecular weights (M(w)): &gt;100, 50-100, 10-50 and &lt;10 kDa. Each HA fraction was characterized by spectroscopic analyses followed by examining Cr(VI) removal on each fraction of HA at pH 1-5. Spectroscopic results indicated that low-M(w) HA was enriched with polar and aromatic domains. These polar, including polar C in aliphatic region, and aromatic groups were the major sites for Cr(VI) reduction because they disappeared rapidly upon interaction with Cr(VI). As a result, low M(w) of HA exhibited greater efficiency of Cr(VI) reduction. Light induced the rapid transfer of electrons between chromate-phenol/carboxyl ester, or the formation of peroxide radicals or H(2)O(2) through the ready decay of peroxy radicals associated with polar substituents, explained the rapid scavenging of Cr(VI) on polar and aromatic groups of HAs under illumination."
1577533,Chen et al. 2011,Synthesis of an Attapulgite Clay@Carbon Nanocomposite Adsorbent by a Hydrothermal Carbonization Process and Their Application in the Removal of Toxic Metal Ions from Water,,Synthesis of an Attapulgite Clay@Carbon Nanocomposite Adsorbent by a Hydrothermal Carbonization Process and Their Application in the Removal of Toxic Metal Ions from Water Abs: 
1577532,Chatterjee and  Luo 2010,Exposure-response of Cr(III)-organic complexes to Saccharomyces cerevisiae,,Exposure-response of Cr(III)-organic complexes to Saccharomyces cerevisiae Abs: 
1577531,Chakravarti et al. 1995,LIQUID MEMBRANE MULTIPLE EMULSION PROCESS OF CHROMIUM(VI) SEPARATION FROM WASTE-WATERS,,LIQUID MEMBRANE MULTIPLE EMULSION PROCESS OF CHROMIUM(VI) SEPARATION FROM WASTE-WATERS Abs: 
1577530,Chakraborty et al. 2005,Studies on extraction of chromium(VI) from acidic solution by emulsion liquid membrane,,Studies on extraction of chromium(VI) from acidic solution by emulsion liquid membrane Abs: 
1577529,Carrington et al. 2007,Electrodeposited sol-gels for electrochemical sensing of Cr(VI),,Electrodeposited sol-gels for electrochemical sensing of Cr(VI) Abs: 
1577527,Campos et al. 2007,Removal of chromate from aqueous solution using treated natural zeolite,,Removal of chromate from aqueous solution using treated natural zeolite Abs: 
1577526,Campos and  Buchler 2005,Removal of chromate from drinking water using powder carbon steel,,Removal of chromate from drinking water using powder carbon steel Abs: 
1577520,Bulgariu et al. 2008,Distribution and migration of chrome in urban soils - Case study: Iasi city (industrial zone),,Distribution and migration of chrome in urban soils - Case study: Iasi city (industrial zone) Abs: 
1577519,Buerge and  Hug 1998,Influence of organic ligands on chromium(VI) reduction by iron(II),,Influence of organic ligands on chromium(VI) reduction by iron(II) Abs: 
1577518,Buerge and  Hug 1997,Kinetics and pH dependence of chromium(VI) reduction by iron(II),,Kinetics and pH dependence of chromium(VI) reduction by iron(II) Abs: 
1577517,Brewster and  Passmore 1994,USE OF ELECTROCHEMICAL IRON GENERATION FOR REMOVING HEAVY-METALS FROM CONTAMINATED GROUNDWATER,,USE OF ELECTROCHEMICAL IRON GENERATION FOR REMOVING HEAVY-METALS FROM CONTAMINATED GROUNDWATER Abs: 
1577516,Bose et al. 1996,"Redox potentials of chromium(V)/(IV), -(V)/(III), and -(IV)/(III) complexes with 2-ethyl-2-hydroxybutanoato(2-/1-) ligands",,"Redox potentials of chromium(V)/(IV), -(V)/(III), and -(IV)/(III) complexes with 2-ethyl-2-hydroxybutanoato(2-/1-) ligands Abs: "
1577515,Biswas et al. 2010,Effects of adjunct therapy of a proprietary herbo-chromium supplement in type 2 diabetes: A randomized clinical trial,,Effects of adjunct therapy of a proprietary herbo-chromium supplement in type 2 diabetes: A randomized clinical trial Abs: 
1577514,Buerge and  Hug 1999,Influence of mineral surfaces on chromium(VI) reduction by iron(II),"BIOSIS COPYRIGHT: BIOL ABS. Chromium(VI) is a priority pollutant of some soils and natural waters in industrial areas. Iron(II), an important natural reductant of Cr(VI), is an option in remediation of contaminated sites, transforming Cr(VI) to essentially nontoxic Cr(III). After kinetics and pathways of this redox reaction had been reported to depend strongly on pH and organic ligands, this study investigated the influence of mineral surfaces. Kinetic measurements with UV-vis in mineral and soil suspensions at pH 5 showed that all minerals tested, except Al2O3, accelerated the Cr(VI) reduction by Fe(II), in the order of alpha-FeOOHnd BFe horizons of a Podzol. The reactions appear to be driven by the high reactivity of adsorbed Fe(II). Whereas adsorbed Cr(VI) was reducible by Fe(II), the sparingly soluble BaCrO 4 was largely protected from reduction. This is of environmental relevance since in many polluted soils, Cr(VI) is partly present as Ba, Ca, Fe, or Pb salts. Kinetic data and reaction pathways are important in the optimization of Fe(II)/mineral mixtures as reductants of Cr(VI) in technical systems, in the evaluation of in-situ remediation of Cr(VI)-contaminated waters and soils by Fe(II), and in qualitative predictions and modeling of Cr(VI) in natural systems.","Influence of mineral surfaces on chromium(VI) reduction by iron(II) Abs: BIOSIS COPYRIGHT: BIOL ABS. Chromium(VI) is a priority pollutant of some soils and natural waters in industrial areas. Iron(II), an important natural reductant of Cr(VI), is an option in remediation of contaminated sites, transforming Cr(VI) to essentially nontoxic Cr(III). After kinetics and pathways of this redox reaction had been reported to depend strongly on pH and organic ligands, this study investigated the influence of mineral surfaces. Kinetic measurements with UV-vis in mineral and soil suspensions at pH 5 showed that all minerals tested, except Al2O3, accelerated the Cr(VI) reduction by Fe(II), in the order of alpha-FeOOHnd BFe horizons of a Podzol. The reactions appear to be driven by the high reactivity of adsorbed Fe(II). Whereas adsorbed Cr(VI) was reducible by Fe(II), the sparingly soluble BaCrO 4 was largely protected from reduction. This is of environmental relevance since in many polluted soils, Cr(VI) is partly present as Ba, Ca, Fe, or Pb salts. Kinetic data and reaction pathways are important in the optimization of Fe(II)/mineral mixtures as reductants of Cr(VI) in technical systems, in the evaluation of in-situ remediation of Cr(VI)-contaminated waters and soils by Fe(II), and in qualitative predictions and modeling of Cr(VI) in natural systems."
1577513,Burbridge et al. 2012,Chromium speciation in river sediment pore water contaminated by tannery effluent,"Cr(VI) is far more soluble and toxic than Cr(III). Sediment pore water was investigated in a river adjacent to the property of a large former tannery, into which Cr-contaminated effluent was discharged over a 55-year period, and where extremely high Cr concentrations have been found in the sediments. Dialysis cells, or peepers, were used to generate depth profiles of Cr concentration in sediment pore water. Samples were analyzed for total Cr using inductively coupled plasma-mass spectrometry (ICP-MS) and for Cr species using high performance liquid chromatography (HPLC)-ICP-MS. The results show an absence of Cr(VI) in all samples. Furthermore, incomplete recovery of Cr(VI) added to the samples collected at the locations with highest sediment Cr concentrations indicate strong reducing conditions at those locations, which are not conducive to the presence of Cr(VI).","Chromium speciation in river sediment pore water contaminated by tannery effluent Abs: Cr(VI) is far more soluble and toxic than Cr(III). Sediment pore water was investigated in a river adjacent to the property of a large former tannery, into which Cr-contaminated effluent was discharged over a 55-year period, and where extremely high Cr concentrations have been found in the sediments. Dialysis cells, or peepers, were used to generate depth profiles of Cr concentration in sediment pore water. Samples were analyzed for total Cr using inductively coupled plasma-mass spectrometry (ICP-MS) and for Cr species using high performance liquid chromatography (HPLC)-ICP-MS. The results show an absence of Cr(VI) in all samples. Furthermore, incomplete recovery of Cr(VI) added to the samples collected at the locations with highest sediment Cr concentrations indicate strong reducing conditions at those locations, which are not conducive to the presence of Cr(VI)."
1577512,Biswas et al. 2004,"A novel indirect spectrofluorimetric method for the ultra, trace analysis of a highly toxic metalloid - Antimony in aqueous medium and its application to metallurgical, medicinal, and biological samples",,"A novel indirect spectrofluorimetric method for the ultra, trace analysis of a highly toxic metalloid - Antimony in aqueous medium and its application to metallurgical, medicinal, and biological samples Abs: "
1577510,Benoit 1976,TOXIC EFFECTS OF HEXAVALENT CHROMIUM ON BROOK TROUT (SALVELINUS-FONTINALIS) AND RAINBOW-TROUT (SALMO-GAIRDNERI),,TOXIC EFFECTS OF HEXAVALENT CHROMIUM ON BROOK TROUT (SALVELINUS-FONTINALIS) AND RAINBOW-TROUT (SALMO-GAIRDNERI) Abs: 
1577509,Bellu et al. 2008,Removal of chromium(VI) and chromium(III) from aqueous solution by grainless stalk of corn,,Removal of chromium(VI) and chromium(III) from aqueous solution by grainless stalk of corn Abs: 
1577508,Bayen et al. 2009,"Micellar effect on the reaction of chromium(VI) oxidation of some representative alpha-hydroxy acids in the presence and absence of 2,2 '-bipyridyl in aqueous acid media: A kinetic study",,"Micellar effect on the reaction of chromium(VI) oxidation of some representative alpha-hydroxy acids in the presence and absence of 2,2 '-bipyridyl in aqueous acid media: A kinetic study Abs: "
1577507,Bayen and  Das 2009,"1,10-PHENANTHROLINE-CATALYSED Cr(VI) OXIDATION OF D-SORBITOL AND D-MANNITOL IN AQUEOUS MICELLAR MEDIA",,"1,10-PHENANTHROLINE-CATALYSED Cr(VI) OXIDATION OF D-SORBITOL AND D-MANNITOL IN AQUEOUS MICELLAR MEDIA Abs: "
1577506,Battaglia-Brunet et al. 2006,Treatment of chromate-polluted groundwater in a 200 dm(3) pilot bioreactor fed with hydrogen,,Treatment of chromate-polluted groundwater in a 200 dm(3) pilot bioreactor fed with hydrogen Abs: 
1577505,Basu et al. 2011,Effect of Some Non Functional Surfactants and Electrolytes on the Hexavalent Chromium Reduction by Glycerol: A Mechanistic Study,,Effect of Some Non Functional Surfactants and Electrolytes on the Hexavalent Chromium Reduction by Glycerol: A Mechanistic Study Abs: 
1577504,Bidwell et al. 1998,Toxicant effects on the zoospore stage of the marine macroalga Ecklonia radiata (Phaeophyta: Laminariales),"BIOSIS COPYRIGHT: BIOL ABS. Marine macroalgae provide both food and habitat for a range of other organisms in nearshore coastal areas. The effect of contaminants upon macroalgae is therefore an important aspect to consider in the regulation of marine effluent discharges. Unfortunately, a lack of standardized bioassay protocols has limited the extent to which macroalgae have been used in routine toxicity testing. In the present study, the effect of selected reference toxicants (hexavalent chromium, copper and zinc) upon germination and growth of zoospores of the marine macroalga Ecklonia radiata (C.Ag.) J.Ag. was investigated in 48 h bioassays. E. radiata is often a dominant member of near-shore subtidal communities in temperate Australia, New Zealand and South Africa, regions in which toxicological data for native species are lacking. Release of zoospores was induced in the laboratory and settled spores were exposed to the metals. Zoospores from 3 different populations in Western Australia and 1","Toxicant effects on the zoospore stage of the marine macroalga Ecklonia radiata (Phaeophyta: Laminariales) Abs: BIOSIS COPYRIGHT: BIOL ABS. Marine macroalgae provide both food and habitat for a range of other organisms in nearshore coastal areas. The effect of contaminants upon macroalgae is therefore an important aspect to consider in the regulation of marine effluent discharges. Unfortunately, a lack of standardized bioassay protocols has limited the extent to which macroalgae have been used in routine toxicity testing. In the present study, the effect of selected reference toxicants (hexavalent chromium, copper and zinc) upon germination and growth of zoospores of the marine macroalga Ecklonia radiata (C.Ag.) J.Ag. was investigated in 48 h bioassays. E. radiata is often a dominant member of near-shore subtidal communities in temperate Australia, New Zealand and South Africa, regions in which toxicological data for native species are lacking. Release of zoospores was induced in the laboratory and settled spores were exposed to the metals. Zoospores from 3 different populations in Western Australia and 1"
1577503,Barrdavid et al. 1995,EPR CHARACTERIZATION OF THE CR-V INTERMEDIATES IN THE CR-VI/V OXIDATIONS OF ORGANIC SUBSTRATES AND OF RELEVANCE TO CR-INDUCED CANCERS,,EPR CHARACTERIZATION OF THE CR-V INTERMEDIATES IN THE CR-VI/V OXIDATIONS OF ORGANIC SUBSTRATES AND OF RELEVANCE TO CR-INDUCED CANCERS Abs: 
1577502,Banerjee and  Sarkar 2011,Amperometric Detection of Hexavalent Chromium with L-DOPA Modified Screen Printed Electrode,,Amperometric Detection of Hexavalent Chromium with L-DOPA Modified Screen Printed Electrode Abs: 
1577501,Balan et al. 2010,SPHAGNUM MOSS PEAT: A GREEN AND ECONOMICAL SORBENT FOR REMOVAL OF HEAVY METALS (Cd and Cr) FROM WASTEWATERS,,SPHAGNUM MOSS PEAT: A GREEN AND ECONOMICAL SORBENT FOR REMOVAL OF HEAVY METALS (Cd and Cr) FROM WASTEWATERS Abs: 
1577500,Balakumar et al. 2006,Micellar catalysis on the electron transfer reactions of iron(III)-polypyridyl complexes with organic sulfides-importance of hydrophobic interactions,,Micellar catalysis on the electron transfer reactions of iron(III)-polypyridyl complexes with organic sulfides-importance of hydrophobic interactions Abs: 
1577499,Babu et al. 2005,Screening of leather auxiliaries for their role in toxic hexavalent chromium formation in leather - posing potential health hazards to the users,,Screening of leather auxiliaries for their role in toxic hexavalent chromium formation in leather - posing potential health hazards to the users Abs: 
1577498,Babu et al. 2004,Removal of toxic Chromium(VI) by the adsorption of activated carbons prepared from Mahua shells,,Removal of toxic Chromium(VI) by the adsorption of activated carbons prepared from Mahua shells Abs: 
1577496,Arslan et al. 2010,Physical and chemical factors affecting the adsorption of Cr(VI) via humic acids extracted from brown coals,,Physical and chemical factors affecting the adsorption of Cr(VI) via humic acids extracted from brown coals Abs: 
1577495,Arrate et al. 2002,Effects of three chemicals on the survival and reproduction of the oligochaete worm Enchytraeus coronatus in chronic toxicity tests,,Effects of three chemicals on the survival and reproduction of the oligochaete worm Enchytraeus coronatus in chronic toxicity tests Abs: 
1577494,Arakawa et al. 2001,Calf-thymus DNA interaction with Cr(III)-gallate and Cr(III)-ethyl gallate studied by FTIR spectroscopy and capillary electrophoresis,,Calf-thymus DNA interaction with Cr(III)-gallate and Cr(III)-ethyl gallate studied by FTIR spectroscopy and capillary electrophoresis Abs: 
1577493,Altas 2009,Effects of chromium (VI) on the activities of ureolytic mixed culture,,Effects of chromium (VI) on the activities of ureolytic mixed culture Abs: 
1577492,Alpaydin et al. 2011,Kinetic study on removal of toxic metal Cr(VI) through a bulk liquid membrane containing p-tert-butylcalix[4]arene derivative,,Kinetic study on removal of toxic metal Cr(VI) through a bulk liquid membrane containing p-tert-butylcalix[4]arene derivative Abs: 
1577491,Alonso et al. 1997,Separation of Cr(VI) with Aliquat 336: Chemical equilibrium modeling,,Separation of Cr(VI) with Aliquat 336: Chemical equilibrium modeling Abs: 
1577490,Anandkumar and  Mandal 2009,Removal of Cr(VI) from aqueous solution using Bael fruit (Aegle marmelos correa) shell as an adsorbent,"In this study, a new activated carbon prepared from non-usable Bael fruit shell (BS) has been used as an efficient low cost adsorbent to remove the Cr(VI) toxic metal from aqueous phase. Batch mode experiments have been performed as a function of initial pH of solution, agitation time, adsorbate concentration and adsorbent dosage. Maximum chromium removal was found at pH 2.0 in an equilibrium time of 240 min by adsorption-coupled reduction. The sorption data fitted satisfactorily with Langmuir as well as Freundlich adsorption model. Evaluation using Langmuir equation gave the monolayer sorption capacity as 17.27 mg/g. Chromium uptake (adsorption-coupled reduction) by Bael fruit shell activated carbon (BSAC) was best described by pseudo-second-order chemisorption model. The progressive changes on surface texture and the confirmation of chromium binding on adsorbent surface at different stages were obtained by the scanning electron microscopy (SEM), energy dispersive X-ray spectroscopy (EDS) and Fourier transform infrared spectrometer (FT-IR) analysis. Phosphoric acid activation played a significant role to develop the well defined pores on adsorbent surface. The results obtained in this study illustrate that the BSAC is expected to be an effective and economically viable adsorbent for Cr(VI) removal from aqueous system.","Removal of Cr(VI) from aqueous solution using Bael fruit (Aegle marmelos correa) shell as an adsorbent Abs: In this study, a new activated carbon prepared from non-usable Bael fruit shell (BS) has been used as an efficient low cost adsorbent to remove the Cr(VI) toxic metal from aqueous phase. Batch mode experiments have been performed as a function of initial pH of solution, agitation time, adsorbate concentration and adsorbent dosage. Maximum chromium removal was found at pH 2.0 in an equilibrium time of 240 min by adsorption-coupled reduction. The sorption data fitted satisfactorily with Langmuir as well as Freundlich adsorption model. Evaluation using Langmuir equation gave the monolayer sorption capacity as 17.27 mg/g. Chromium uptake (adsorption-coupled reduction) by Bael fruit shell activated carbon (BSAC) was best described by pseudo-second-order chemisorption model. The progressive changes on surface texture and the confirmation of chromium binding on adsorbent surface at different stages were obtained by the scanning electron microscopy (SEM), energy dispersive X-ray spectroscopy (EDS) and Fourier transform infrared spectrometer (FT-IR) analysis. Phosphoric acid activation played a significant role to develop the well defined pores on adsorbent surface. The results obtained in this study illustrate that the BSAC is expected to be an effective and economically viable adsorbent for Cr(VI) removal from aqueous system."
1577489,Al-Hamdan and  Reddy 2006,Geochemical reconnaissance of heavy metals in kaolin after electrokinetic remedation,,Geochemical reconnaissance of heavy metals in kaolin after electrokinetic remedation Abs: 
1577488,Alguacil et al. 2002,Recovery of chromium(VI) from hydrochloric liquors using the resin Dowex 1x8,,Recovery of chromium(VI) from hydrochloric liquors using the resin Dowex 1x8 Abs: 
1577487,Albadarin et al. 2011,Retention of toxic chromium from aqueous phase by H3PO4-activated lignin: Effect of salts and desorption studies,,Retention of toxic chromium from aqueous phase by H3PO4-activated lignin: Effect of salts and desorption studies Abs: 
1577486,Alatorre et al. 1998,Reduction of hexavalent chromium by polypyrrole deposited on different carbon substrates,,Reduction of hexavalent chromium by polypyrrole deposited on different carbon substrates Abs: 
1577485,Alam et al. 2008,Corrosion-protective performance of nano polyaniline/ferrite dispersed alkyd coatings,,Corrosion-protective performance of nano polyaniline/ferrite dispersed alkyd coatings Abs: 
1577484,Aksu et al. 1999,"A comparative study for the biosorption characteristics of chromium(VI) on Ca-alginate, agarose and immobilized C-vulgaris in a continuous packed bed column",,"A comparative study for the biosorption characteristics of chromium(VI) on Ca-alginate, agarose and immobilized C-vulgaris in a continuous packed bed column Abs: "
1577483,Aksu and  Akpinar 2000,Simultaneous adsorption of phenol and chromium(VI) from binary mixtures onto powdered activated carbon,,Simultaneous adsorption of phenol and chromium(VI) from binary mixtures onto powdered activated carbon Abs: 
1577482,Akkus et al. 2009,Synthesis of Calix(aza)crown and its Oligomeric Analogue for the Extraction of Selected Metal Cations and Dichromate Anions,,Synthesis of Calix(aza)crown and its Oligomeric Analogue for the Extraction of Selected Metal Cations and Dichromate Anions Abs: 
1577480,Ajmal et al. 1993,SURFACE ENTRAPMENT OF TOXIC METALS FROM ELECTROPLATING WASTE AND THEIR POSSIBLE RECOVERY,"BIOSIS COPYRIGHT: BIOL ABS. Heavy metal ions such as Cr, Ni, Cu, Cd and Zn have been removed from the electroplating waste using Fe(III) hydroxide as adsorbent. The maximum removal of these metal ions (> 90%) occurred at pH 8 to 9. Removal of SO42- (98%) occurred at pH 4. Anions were found to play a negative role in the adsorption phenomenon. Metal ion sorption has been found to decrease with increasing anionic concentrations. The methodology proposed might provide an inexpensive and economical procedure for removal and recovery of toxic metals from electroplating wastes.","SURFACE ENTRAPMENT OF TOXIC METALS FROM ELECTROPLATING WASTE AND THEIR POSSIBLE RECOVERY Abs: BIOSIS COPYRIGHT: BIOL ABS. Heavy metal ions such as Cr, Ni, Cu, Cd and Zn have been removed from the electroplating waste using Fe(III) hydroxide as adsorbent. The maximum removal of these metal ions (> 90%) occurred at pH 8 to 9. Removal of SO42- (98%) occurred at pH 4. Anions were found to play a negative role in the adsorption phenomenon. Metal ion sorption has been found to decrease with increasing anionic concentrations. The methodology proposed might provide an inexpensive and economical procedure for removal and recovery of toxic metals from electroplating wastes."
1577479,Ahmad and  Singh 2005,Kinetics of micelle catalysed oxidation of ortho-toluidine,,Kinetics of micelle catalysed oxidation of ortho-toluidine Abs: 
1577478,Agrawal and  Bajpai 2011,Dynamic Column Adsorption Studies of Toxic Cr(VI) Ions onto Iron Oxide Loaded Gelatin Nanoparticles,,Dynamic Column Adsorption Studies of Toxic Cr(VI) Ions onto Iron Oxide Loaded Gelatin Nanoparticles Abs: 
1577477,Afolaranmi et al. 2012,Distribution of metal released from cobalt-chromium alloy orthopaedic wear particles implanted into air pouches in mice,,Distribution of metal released from cobalt-chromium alloy orthopaedic wear particles implanted into air pouches in mice Abs: 
1577476,Adams et al. 1995,"OZONE, HYDROGEN-PEROXIDE OZONE AND UV OZONE TREATMENT OF CHROMIUM-COMPLEX AND COPPER-COMPLEX DYES - DECOLORIZATION AND METAL RELEASE",,"OZONE, HYDROGEN-PEROXIDE OZONE AND UV OZONE TREATMENT OF CHROMIUM-COMPLEX AND COPPER-COMPLEX DYES - DECOLORIZATION AND METAL RELEASE Abs: "
1577475,Adach et al. 1995,"Interaction of carcinogenic chromium(VI) oxide, CrO3, with main nonenzymatic cellular reductants at physiological conditions. Electronic spectra and magnetic studies",,"Interaction of carcinogenic chromium(VI) oxide, CrO3, with main nonenzymatic cellular reductants at physiological conditions. Electronic spectra and magnetic studies Abs: "
1577474,Abu El-Saad et al. 2010,N-acetylcysteine an Allium plant compound protects against chromium (VI) induced oxidant stress and ultrastructural changes of pancreatic beta-cells in rats,,N-acetylcysteine an Allium plant compound protects against chromium (VI) induced oxidant stress and ultrastructural changes of pancreatic beta-cells in rats Abs: 
1577473,Abdollahi 2001,Simultaneous spectrophotometric determination of chromium(VI) and iron(III) with chromogenic mixed reagents by H-point standard addition method and partial least squares regression,,Simultaneous spectrophotometric determination of chromium(VI) and iron(III) with chromogenic mixed reagents by H-point standard addition method and partial least squares regression Abs: 
1577472,Abbasi and  Soni 1984,TOXICITY OF LOWER THAN PERMISSIBLE LEVELS OF CHROMIUM (VI) TO THE FRESH-WATER TELEOST NURIA-DENRICUS,,TOXICITY OF LOWER THAN PERMISSIBLE LEVELS OF CHROMIUM (VI) TO THE FRESH-WATER TELEOST NURIA-DENRICUS Abs: 
1577286,Sillerová et al. 2013,Brewers draff as a new low-cost sorbent for chromium (VI): comparison with other biosorbents,"In this study, used brewers draff was investigated as a novel sorbent for Cr(VI) and compared with other biosorbents (grape waste, peat moss, and sawdust). FTIR-ATR, BET analysis, and pHPZC determination were used to characterize the sorbents. Kinetic and equilibrium experiments were performed, and two empirical models, Langmuir and Freundlich, were used to describe Cr adsorption. Additionally, packed bed column experiments were also performed. In order to identify possible reduction processes, ion exchange separation on the AG1-X8 resin was used to separate the anionic Cr(VI) and the reduced cationic Cr(III) from the aqueous phase after biosorption. Cr(VI) removal was pH-dependent and fitted well both the Langmuir and the Freundlich isotherm models. The ion exchange separation showed that Cr(VI) reduction had occurred in the solution during biosorption. The efficiency of draff as a biosorbent was comparable (or even higher) to highly organic materials (e.g., composted peat), showing its potential application for Cr(VI) decontamination.","Brewers draff as a new low-cost sorbent for chromium (VI): comparison with other biosorbents Abs: In this study, used brewers draff was investigated as a novel sorbent for Cr(VI) and compared with other biosorbents (grape waste, peat moss, and sawdust). FTIR-ATR, BET analysis, and pHPZC determination were used to characterize the sorbents. Kinetic and equilibrium experiments were performed, and two empirical models, Langmuir and Freundlich, were used to describe Cr adsorption. Additionally, packed bed column experiments were also performed. In order to identify possible reduction processes, ion exchange separation on the AG1-X8 resin was used to separate the anionic Cr(VI) and the reduced cationic Cr(III) from the aqueous phase after biosorption. Cr(VI) removal was pH-dependent and fitted well both the Langmuir and the Freundlich isotherm models. The ion exchange separation showed that Cr(VI) reduction had occurred in the solution during biosorption. The efficiency of draff as a biosorbent was comparable (or even higher) to highly organic materials (e.g., composted peat), showing its potential application for Cr(VI) decontamination."
1577285,Nitiyanontakit et al. 2013,Hybrid flow analyzer for automatic hollow-fiber-assisted ionic liquid-based liquid-phase microextraction with in-line membrane regeneration,"The proof-of-concept of a new methodology for in-line hollow-fiber (HF)-assisted three-phase liquid-phase microextraction (LPME) allowing for handling of the feed and acceptor aqueous solutions and of minute volumes of the organic extracting phase in a programmable flow mode is reported in this paper. The flow analyzer fosters in-line anchoring of ionic-liquid-laden extracting solution (10 % (v/v) methyltrioctyl ammonium chloride in kerosene) in the pores of a single-strand microporous polypropylene HF, and regeneration of the liquid-phase membrane itself for each individual analysis cycle in a fully automated mode. Using hexavalent chromium as a model analyte and 1,5-diphenylcarbazide as a chromogenic probe in the acceptor solution, the flow-based HF-LPME hyphenated system was harnessed to the clean-up of troublesome samples (viz., domestic wastewater and soil leachates) with concomitant enrichment of target species. Distinct extraction modes and chemistries were assessed for enhanced Cr(VI) permeability. A single sample plug was subjected to a twofold backward-forward flow extraction so as to decrease the thickness of the boundary layer at the HF shell side for improved extraction efficiency. Under the optimized physicochemical variables, a limit of detection of 4.6 ?g?L(-1) Cr(VI), a dynamic linear range of up to 500 ?g?L(-1) and intermediate precision better than 10 % were obtained for a sample volume of 2.8 mL buffered at pH 4 and a volume of organic extractant of 120 ?L, with an enrichment factor of ca. 11 for a sample residence time in the donor compartment of merely 4.5 min. Analyte recoveries in domestic wastewaters were ?83 % using external calibration with relative standard deviations better than 14 %, thereby demonstrating the expedient clean-up of samples with elevated content of dissolved organic carbon. The automatic HF-LPME method was validated in terms of bias against the SRM 2701 (NIST soil) preceded by the EPA alkaline digestion method 3060A. No significant differences between Cr(VI) concentration as obtained with the automatic HF-LPME system (546?±?57 mg?kg(-1)) and the certified value (551.2?±?17.2 mg?kg(-1), expressed as mean ± combined uncertainty) were encountered at the 0.05 significance level.","Hybrid flow analyzer for automatic hollow-fiber-assisted ionic liquid-based liquid-phase microextraction with in-line membrane regeneration Abs: The proof-of-concept of a new methodology for in-line hollow-fiber (HF)-assisted three-phase liquid-phase microextraction (LPME) allowing for handling of the feed and acceptor aqueous solutions and of minute volumes of the organic extracting phase in a programmable flow mode is reported in this paper. The flow analyzer fosters in-line anchoring of ionic-liquid-laden extracting solution (10 % (v/v) methyltrioctyl ammonium chloride in kerosene) in the pores of a single-strand microporous polypropylene HF, and regeneration of the liquid-phase membrane itself for each individual analysis cycle in a fully automated mode. Using hexavalent chromium as a model analyte and 1,5-diphenylcarbazide as a chromogenic probe in the acceptor solution, the flow-based HF-LPME hyphenated system was harnessed to the clean-up of troublesome samples (viz., domestic wastewater and soil leachates) with concomitant enrichment of target species. Distinct extraction modes and chemistries were assessed for enhanced Cr(VI) permeability. A single sample plug was subjected to a twofold backward-forward flow extraction so as to decrease the thickness of the boundary layer at the HF shell side for improved extraction efficiency. Under the optimized physicochemical variables, a limit of detection of 4.6 ?g?L(-1) Cr(VI), a dynamic linear range of up to 500 ?g?L(-1) and intermediate precision better than 10 % were obtained for a sample volume of 2.8 mL buffered at pH 4 and a volume of organic extractant of 120 ?L, with an enrichment factor of ca. 11 for a sample residence time in the donor compartment of merely 4.5 min. Analyte recoveries in domestic wastewaters were ?83 % using external calibration with relative standard deviations better than 14 %, thereby demonstrating the expedient clean-up of samples with elevated content of dissolved organic carbon. The automatic HF-LPME method was validated in terms of bias against the SRM 2701 (NIST soil) preceded by the EPA alkaline digestion method 3060A. No significant differences between Cr(VI) concentration as obtained with the automatic HF-LPME system (546?±?57 mg?kg(-1)) and the certified value (551.2?±?17.2 mg?kg(-1), expressed as mean ± combined uncertainty) were encountered at the 0.05 significance level."
1577283,Wu et al. 2013,Adsorption of hexavalent chromium from aqueous solutions by graphene modified with cetyltrimethylammonium bromide,"In this study, cetyltrimethylammonium bromide was chosen to modify graphene, which was prepared using a modified Hummers' method. The characteristics of graphene and modified graphene were characterized by X-ray diffraction, Fourier transform infrared spectrum, X-ray photoelectron spectroscopy, transmission electron microscopy, and scanning electron microscopy. The effect factors including pH, contact time, temperature, and dosage on the adsorption properties of Cr(VI) onto graphene and modified graphene were investigated. Batch experiments were conducted to evaluate the adsorbance of Cr(VI) from aqueous solution using graphene and modified graphene as the adsorbent under different conditions. The results revealed that the optimal pH for the adsorption was about 2, and the best suitable temperature was at 293 K. The adsorption processes were rapid within the first 5 min and reached equilibrium in about 40 min. The adsorption kinetics fitted well with pseudo-second-order model. The adsorption capacity of Cr(VI) on modified graphene inferred from the Langmuir model was 21.57 mg/g at 293 K. The thermodynamic parameters indicated that the adsorption of Cr(VI) onto modified graphene was an exothermic and spontaneous process.","Adsorption of hexavalent chromium from aqueous solutions by graphene modified with cetyltrimethylammonium bromide Abs: In this study, cetyltrimethylammonium bromide was chosen to modify graphene, which was prepared using a modified Hummers' method. The characteristics of graphene and modified graphene were characterized by X-ray diffraction, Fourier transform infrared spectrum, X-ray photoelectron spectroscopy, transmission electron microscopy, and scanning electron microscopy. The effect factors including pH, contact time, temperature, and dosage on the adsorption properties of Cr(VI) onto graphene and modified graphene were investigated. Batch experiments were conducted to evaluate the adsorbance of Cr(VI) from aqueous solution using graphene and modified graphene as the adsorbent under different conditions. The results revealed that the optimal pH for the adsorption was about 2, and the best suitable temperature was at 293 K. The adsorption processes were rapid within the first 5 min and reached equilibrium in about 40 min. The adsorption kinetics fitted well with pseudo-second-order model. The adsorption capacity of Cr(VI) on modified graphene inferred from the Langmuir model was 21.57 mg/g at 293 K. The thermodynamic parameters indicated that the adsorption of Cr(VI) onto modified graphene was an exothermic and spontaneous process."
1577281,Oujja et al. 2013,Wavelength and pulse duration effects on laser induced changes on raw pigments used in paintings,"In this study, the reaction of widely used artist's pigments in raw form to pulsed laser radiation of different wavelengths and pulse duration was investigated. Vermilion, lead chromate and malachite (in the form of pellets) were irradiated using laser pulses of 500 fs at 248 nm, and pulses of 150 ps and 15 ns at 1064 and 213 nm. Optical microscopy, colorimetry, spectrofluorimetry, micro-Raman spectroscopy and X-ray photoelectron spectroscopy were employed to characterize the physicochemical changes induced to the pigments. Change of crystalline phase was identified for vermilion while reduction processes take place for lead chromate and malachite. It was found that these effects were minimized by application of ultraviolet ultrashort pulses (of femtosecond and picosecond duration) as compared with changes occurring by pulsed infrared irradiation (of both picosecond and nanosecond duration). The results presented are discussed in relation to previous research on painted mock-ups in order to elucidate the role and significance of the binding media in the laser induced discoloration of painted surfaces and thus to propose optimum laser cleaning practices.","Wavelength and pulse duration effects on laser induced changes on raw pigments used in paintings Abs: In this study, the reaction of widely used artist's pigments in raw form to pulsed laser radiation of different wavelengths and pulse duration was investigated. Vermilion, lead chromate and malachite (in the form of pellets) were irradiated using laser pulses of 500 fs at 248 nm, and pulses of 150 ps and 15 ns at 1064 and 213 nm. Optical microscopy, colorimetry, spectrofluorimetry, micro-Raman spectroscopy and X-ray photoelectron spectroscopy were employed to characterize the physicochemical changes induced to the pigments. Change of crystalline phase was identified for vermilion while reduction processes take place for lead chromate and malachite. It was found that these effects were minimized by application of ultraviolet ultrashort pulses (of femtosecond and picosecond duration) as compared with changes occurring by pulsed infrared irradiation (of both picosecond and nanosecond duration). The results presented are discussed in relation to previous research on painted mock-ups in order to elucidate the role and significance of the binding media in the laser induced discoloration of painted surfaces and thus to propose optimum laser cleaning practices."
1577280,Tekerlekopoulou et al. 2013,Modelling of biological Cr(VI) removal in draw-fill reactors using microorganisms in suspended and attached growth systems,"The kinetics of hexavalent chromium bio-reduction in draw-fill suspended and attached growth reactors was examined using sugar as substrate and indigenous microorganisms from the industrial sludge of the Hellenic Aerospace Industry. Initially, experiments in suspended growth batch reactors for Cr (VI) concentrations of 1.4-110 mg/l were carried out, to extensively study the behaviour of a mixed culture. The maximum Cr(VI) reduction rate of 2 mg/l h was achieved for initial concentration 12.85 mg/l with biomass production rate 4.1 mg biomass/l h. Analysis of the microbial structure in the batch reactor culture indicated that the dominant bacterial communities were constituted by bacterial members of Raoultella sp., Citrobacter sp., Klebsiella sp., Salmonella sp., Achromobacter sp. and Kerstersia sp. while the dominant fungal strain was that of Pichia jadinii. Experiments using the same mixed culture were also carried out in packed-bed reactors with plastic support media. High removal rates were achieved (2.0 mg/l h) even in high initial concentrations (109 mg/l). A combination of the model of Tsao and Hanson for growth enhancement and that of Aiba and Shoda for growth inhibition was used in order to describe and predict the process of Cr(VI) bio-reduction in suspended growth and packed-bed reactors. Kinetic constants of the equation obtained from both batch (or draw-fill) culture experiments. In the draw-fill experiments at the packed-bed reactor, hexavalent chromium inhibitory effects were minimized increasing the inhibitory constant value K(i)' at 148.5 mg/l, compared to suspended growth experiments which was K(i) = 8.219 mg/l. The model adequately predicts hexavalent chromium reduction in both batch reactors for all initial concentrations tested.","Modelling of biological Cr(VI) removal in draw-fill reactors using microorganisms in suspended and attached growth systems Abs: The kinetics of hexavalent chromium bio-reduction in draw-fill suspended and attached growth reactors was examined using sugar as substrate and indigenous microorganisms from the industrial sludge of the Hellenic Aerospace Industry. Initially, experiments in suspended growth batch reactors for Cr (VI) concentrations of 1.4-110 mg/l were carried out, to extensively study the behaviour of a mixed culture. The maximum Cr(VI) reduction rate of 2 mg/l h was achieved for initial concentration 12.85 mg/l with biomass production rate 4.1 mg biomass/l h. Analysis of the microbial structure in the batch reactor culture indicated that the dominant bacterial communities were constituted by bacterial members of Raoultella sp., Citrobacter sp., Klebsiella sp., Salmonella sp., Achromobacter sp. and Kerstersia sp. while the dominant fungal strain was that of Pichia jadinii. Experiments using the same mixed culture were also carried out in packed-bed reactors with plastic support media. High removal rates were achieved (2.0 mg/l h) even in high initial concentrations (109 mg/l). A combination of the model of Tsao and Hanson for growth enhancement and that of Aiba and Shoda for growth inhibition was used in order to describe and predict the process of Cr(VI) bio-reduction in suspended growth and packed-bed reactors. Kinetic constants of the equation obtained from both batch (or draw-fill) culture experiments. In the draw-fill experiments at the packed-bed reactor, hexavalent chromium inhibitory effects were minimized increasing the inhibitory constant value K(i)' at 148.5 mg/l, compared to suspended growth experiments which was K(i) = 8.219 mg/l. The model adequately predicts hexavalent chromium reduction in both batch reactors for all initial concentrations tested."
1577279,Field et al. ,"Hexavalent chromium reduction by Cellulomonas sp. strain ES6: the influence of carbon source, iron minerals, and electron shuttling compounds","The reduction of hexavalent chromium, Cr(VI), to trivalent chromium, Cr(III), can be an important aspect of remediation processes at contaminated sites. Cellulomonas species are found at several Cr(VI) contaminated and uncontaminated locations at the Department of Energy site in Hanford, Washington. Members of this genus have demonstrated the ability to effectively reduce Cr(VI) to Cr(III) fermentatively and therefore play a potential role in Cr(VI) remediation at this site. Batch studies were conducted with Cellulomonas sp. strain ES6 to assess the influence of various carbon sources, iron minerals, and electron shuttling compounds on Cr(VI) reduction rates as these chemical species are likely to be present in, or added to, the environment during in situ bioremediation. Results indicated that the type of carbon source as well as the type of electron shuttle present influenced Cr(VI) reduction rates. Molasses stimulated Cr(VI) reduction more effectively than pure sucrose, presumably due to presence of more easily utilizable sugars, electron shuttling compounds or compounds with direct Cr(VI) reduction capabilities. Cr(VI) reduction rates increased with increasing concentration of anthraquinone-2,6-disulfonate (AQDS) regardless of the carbon source. The presence of iron minerals and their concentrations did not significantly influence Cr(VI) reduction rates. However, strain ES6 or AQDS could directly reduce surface-associated Fe(III) to Fe(II), which was capable of reducing Cr(VI) at a near instantaneous rate. These results suggest the rate limiting step in these systems was the transfer of electrons from strain ES6 to the intermediate or terminal electron acceptor whether that was Cr(VI), Fe(III), or AQDS.","Hexavalent chromium reduction by Cellulomonas sp. strain ES6: the influence of carbon source, iron minerals, and electron shuttling compounds Abs: The reduction of hexavalent chromium, Cr(VI), to trivalent chromium, Cr(III), can be an important aspect of remediation processes at contaminated sites. Cellulomonas species are found at several Cr(VI) contaminated and uncontaminated locations at the Department of Energy site in Hanford, Washington. Members of this genus have demonstrated the ability to effectively reduce Cr(VI) to Cr(III) fermentatively and therefore play a potential role in Cr(VI) remediation at this site. Batch studies were conducted with Cellulomonas sp. strain ES6 to assess the influence of various carbon sources, iron minerals, and electron shuttling compounds on Cr(VI) reduction rates as these chemical species are likely to be present in, or added to, the environment during in situ bioremediation. Results indicated that the type of carbon source as well as the type of electron shuttle present influenced Cr(VI) reduction rates. Molasses stimulated Cr(VI) reduction more effectively than pure sucrose, presumably due to presence of more easily utilizable sugars, electron shuttling compounds or compounds with direct Cr(VI) reduction capabilities. Cr(VI) reduction rates increased with increasing concentration of anthraquinone-2,6-disulfonate (AQDS) regardless of the carbon source. The presence of iron minerals and their concentrations did not significantly influence Cr(VI) reduction rates. However, strain ES6 or AQDS could directly reduce surface-associated Fe(III) to Fe(II), which was capable of reducing Cr(VI) at a near instantaneous rate. These results suggest the rate limiting step in these systems was the transfer of electrons from strain ES6 to the intermediate or terminal electron acceptor whether that was Cr(VI), Fe(III), or AQDS."
1577272,Verma and  Singh 2013,Isolation and process parameter optimization of Brevibacterium casei for simultaneous bioremediation of hexavalent chromium and pentachlorophenol,"Chromate and pentachlorophenol are major pollutants discharged through tanneries. Three bacteria resistant to high Cr(6+) and PCP concentrations simultaneously were isolated. The TVS-3 strain was tolerant to highest 850?mg l(-1) Cr(6+) and 1000?mg l(-1) PCP concentration and concomitantly reduced 69% Cr(6+) and degraded 72% PCP within 168?h at pH 7.5, 35?±?1°C temperature, was selected and identified as Brevibacterium casei. At 168?h of growth, bacterium showed maximum PCP utilization of 720?mg l(-1) and released 900?mg l(-1) chloride ion. The bacterium exhibited remarkable ability to significantly reduce Cr(6+) and degrade PCP in presence of other metals, between 100-120?rpm aeration and over broad pH (6.5-10.0) and temperature (30-40°C) range. Maximum 78% Cr(6+) reduction and 82% PCP degradation was observed at pH 8.0, 35?±?1°C within 168?h of incubation, 120?rpm and initial concentration of 850?mg l(-1) Cr(6+) and 1000?mg l(-1) PCP. This is the first study reporting 78% Cr(6+) reduction and 82% PCP degradation simultaneously by single native bacteria under wide growth conditions utilizing PCP as sole carbon source. This bacterium may potentially be useful for simultaneous bioremediation of Cr(6+) and PCP containing wastes in the environment.","Isolation and process parameter optimization of Brevibacterium casei for simultaneous bioremediation of hexavalent chromium and pentachlorophenol Abs: Chromate and pentachlorophenol are major pollutants discharged through tanneries. Three bacteria resistant to high Cr(6+) and PCP concentrations simultaneously were isolated. The TVS-3 strain was tolerant to highest 850?mg l(-1) Cr(6+) and 1000?mg l(-1) PCP concentration and concomitantly reduced 69% Cr(6+) and degraded 72% PCP within 168?h at pH 7.5, 35?±?1°C temperature, was selected and identified as Brevibacterium casei. At 168?h of growth, bacterium showed maximum PCP utilization of 720?mg l(-1) and released 900?mg l(-1) chloride ion. The bacterium exhibited remarkable ability to significantly reduce Cr(6+) and degrade PCP in presence of other metals, between 100-120?rpm aeration and over broad pH (6.5-10.0) and temperature (30-40°C) range. Maximum 78% Cr(6+) reduction and 82% PCP degradation was observed at pH 8.0, 35?±?1°C within 168?h of incubation, 120?rpm and initial concentration of 850?mg l(-1) Cr(6+) and 1000?mg l(-1) PCP. This is the first study reporting 78% Cr(6+) reduction and 82% PCP degradation simultaneously by single native bacteria under wide growth conditions utilizing PCP as sole carbon source. This bacterium may potentially be useful for simultaneous bioremediation of Cr(6+) and PCP containing wastes in the environment."
1577133,Kawamoto et al. 1999,"Health Hazard Evaluation Report HETA 96-0016-2777, Eagle-Picher Industries, Joplin, Missouri","See also PB-269 142 and PB-270 947. ober 20, 1995, the National Institute for Occupational Safety and Health (NIOSH) received a request for a health hazard evaluation (HHE) at Eagle-Picher Industries, Inc., in Joplin, Missouri. The request was submitted by a representative of the United Steelworkers of America Rubber/Plastic Industry Conference, in Akron, Ohio. The request concerned potential employee exposures to a number of chemical hazards, particularly lithium, mercury, and lead chromate, in various operations at the facility. Following a walkthrough survey at the plant on December 12-13, 1995, the NIOSH investigators focused on lithium exposures in the process room, pill room, and dry room 108; mercury exposures in the pit and pasting room; identifying an orange substance on the walls in the potting area; and investigating the cause of eye irritation in the solder room. NIOSH investigators returned to the plant on April 17, 1996, and conducted another walkthrough survey to plan for two full days of industrial hygiene and biological monitoring of employee exposures to lithium and mercury, which took place on April 18-19, 1996.","Health Hazard Evaluation Report HETA 96-0016-2777, Eagle-Picher Industries, Joplin, Missouri Abs: See also PB-269 142 and PB-270 947. ober 20, 1995, the National Institute for Occupational Safety and Health (NIOSH) received a request for a health hazard evaluation (HHE) at Eagle-Picher Industries, Inc., in Joplin, Missouri. The request was submitted by a representative of the United Steelworkers of America Rubber/Plastic Industry Conference, in Akron, Ohio. The request concerned potential employee exposures to a number of chemical hazards, particularly lithium, mercury, and lead chromate, in various operations at the facility. Following a walkthrough survey at the plant on December 12-13, 1995, the NIOSH investigators focused on lithium exposures in the process room, pill room, and dry room 108; mercury exposures in the pit and pasting room; identifying an orange substance on the walls in the potting area; and investigating the cause of eye irritation in the solder room. NIOSH investigators returned to the plant on April 17, 1996, and conducted another walkthrough survey to plan for two full days of industrial hygiene and biological monitoring of employee exposures to lithium and mercury, which took place on April 18-19, 1996."
1577132,Hewitt and  Cragin 1992,Potential Cause for Low Lead and Chromium Recoveries during Acid Extractions,"When high concentrations (&amp;gt; or equal to l00 mg/L) of Pb and Cr (IV) are present together in solution, PbCrO4 precipitates, resulting in losses of these two metals. Moderate acidification with 1-2% HN03 does not prevent precipitation loss. Caution is necessary when preparing standard solutions or handling acidic extracts of environmental samples containing high levels of Pb and Cr, since undetected formation of metal chromates will result in low recoveries of these metals....Acid extraction, Hazardous wastes, Lead paint, Contaminated soils, Lead chromate.","Potential Cause for Low Lead and Chromium Recoveries during Acid Extractions Abs: When high concentrations (&amp;gt; or equal to l00 mg/L) of Pb and Cr (IV) are present together in solution, PbCrO4 precipitates, resulting in losses of these two metals. Moderate acidification with 1-2% HN03 does not prevent precipitation loss. Caution is necessary when preparing standard solutions or handling acidic extracts of environmental samples containing high levels of Pb and Cr, since undetected formation of metal chromates will result in low recoveries of these metals....Acid extraction, Hazardous wastes, Lead paint, Contaminated soils, Lead chromate."
1577131,Fox 2000,Chromium Concentration Bias in the Particle Size Distribution of Primer Overspray,"Master's thesis. rce aircraft-painting operations create clouds of paint overspray that contain strontium chromate, a confirmed carcinogen, which poses an exposure hazard to painters. It is often assumed that all particles in paint overspray have the same chemical composition as the original paint mixture, however differences in composition may occur in various particle sizes. Because particle size affects where in the respiratory system a particle deposits, actual exposures to a specific chemical may vary. Paint particles greater than 2.5 um are deposited in the upper respiratory system and will be eliminated by physiological removal mechanisms. Particles less than 2.5 um will deposit in the pulmonary region of the lungs where removal processes are slower. Currently it is assumed for the purposes of industrial hygiene evaluations that there is an equal distribution of chromate across all paint particle sizes.","Chromium Concentration Bias in the Particle Size Distribution of Primer Overspray Abs: Master's thesis. rce aircraft-painting operations create clouds of paint overspray that contain strontium chromate, a confirmed carcinogen, which poses an exposure hazard to painters. It is often assumed that all particles in paint overspray have the same chemical composition as the original paint mixture, however differences in composition may occur in various particle sizes. Because particle size affects where in the respiratory system a particle deposits, actual exposures to a specific chemical may vary. Paint particles greater than 2.5 um are deposited in the upper respiratory system and will be eliminated by physiological removal mechanisms. Particles less than 2.5 um will deposit in the pulmonary region of the lungs where removal processes are slower. Currently it is assumed for the purposes of industrial hygiene evaluations that there is an equal distribution of chromate across all paint particle sizes."
1577130,DuPont 1992,Carcinogenicity,"RATS AND DOGS WERE FED AT 0, 2000, 5000, AND 20000 PPM FOR 90 DAYS. ITIES WERE OBSERVED AT TREATMENT DOSE LEVELS IN DOGS (3/8 DEATHS AT THE PM LEVELS). SIGNS OF A RESPONSE INCLUDED DISCOLORATION, MOTOR ATAXIA AND SIONS. MARKED MICROSCOPIC LESION OF TUBULAR EPITHELIUM WERE OBSERVED IN EPIDEMIOLOGICAL STUDIES SHOWED BRONCHOGENIC CARCINOMA OCCURRENCE IN EXPOSED TO THE CHEMICAL AT WORK PLACE. CARCINOGENICITY FOR LIGHT CHROME YELLOW PIGMENT, MEDIUM CHROME YELLOW T, PRIMROSE CHROME YELLOW PIGMENT, AND MOLYBDATE ORANGE PIGMENT IS OF LOW N BASED ON THE RESULTS OF A 90-DAY FEEDING STUDY IN RATS AND DOGS. MALES MALES (4/SEX/DOSE) WERE FED 2000, 5000 AND 20000 PPM, EQUIVALENT TO 50, D 500 MG/KG/DAY. NO TREATMENT-RELATED TUMORS DEVELOPED IN THE ANIMALS. UDY WAS LIMITED TO HIGH MORTALITY AT 5000 PPM (EXCEPT MEDIUM CHROME AND LIGHT CHROME YELLOW) AND 20000 PPM. OGENICITY CANNOT BE DETERMINED BASED ON SUBCUTANEOUS INJECTION OF LEAD TE. RATS EXPOSED TO LEAD CHROMATE AS CHROMIUM YELLOW OR CHROMIUM ORANGE T DEVELOPED TUMORS (UNSPECIFIED TYPE); INCIDENCE WAS 26/40 WITH BOTH TS). NO OTHER DETAILS WERE PROVIDED. CARCINOGENICITY CANNOT BE INED BASED ON INHALATION (OCCUPATIONAL) EXPOSURE TO LEAD CHROMATE TS IN HUMANS. WORKERS EXPOSED TO LEAD CHROMATE PIGMENTS HAVE SLIGHT IN INCIDENCE OF LUNG CANCER. THE STUDY IS LIMITED BECAUSE THE WORKERS VE BEEN EXPOSED ONLY TO ZINC CHROMATE OR TO DUST COMPOSED OF MIXTURES OF ND ZINC CHROMATE PIGMENTS. RPORATE TOXICOLOGISTS PRESENTED A SUMMARY OF TOXICOLOGICAL EFFECTS T TO EXIST AT THE TIME (1981) FOR LEAD CHROMATES, BASED ON ANIMAL AND OBSERVATIONAL STUDIES, THE LATTER MOSTLY MORTALITY STUDIES OF WORKER S IN SEVERAL COUNTRIES. VERY LITTLE SYSTEMATIC DATA WERE PRESENTED, AN OVERALL QUALITATIVE INTERPRETATION (E.G., MANUFACTURE OF LEAD AND HROMATE PIGMENTS WERE ASSOCIATED WITH AN APPROXIMATE 2-FOLD LUNG CANCER AND DUST CONCENTRATIONS WERE AN IMPORTANT FACTOR). THE COMPARATIVE S CITED SHOW LUNG CANCER RISKS IN CHROMATE ORE PROCESSING PLANTS WAS THAN IN THE PIGMENTS INDUSTRY.","Carcinogenicity Abs: RATS AND DOGS WERE FED AT 0, 2000, 5000, AND 20000 PPM FOR 90 DAYS. ITIES WERE OBSERVED AT TREATMENT DOSE LEVELS IN DOGS (3/8 DEATHS AT THE PM LEVELS). SIGNS OF A RESPONSE INCLUDED DISCOLORATION, MOTOR ATAXIA AND SIONS. MARKED MICROSCOPIC LESION OF TUBULAR EPITHELIUM WERE OBSERVED IN EPIDEMIOLOGICAL STUDIES SHOWED BRONCHOGENIC CARCINOMA OCCURRENCE IN EXPOSED TO THE CHEMICAL AT WORK PLACE. CARCINOGENICITY FOR LIGHT CHROME YELLOW PIGMENT, MEDIUM CHROME YELLOW T, PRIMROSE CHROME YELLOW PIGMENT, AND MOLYBDATE ORANGE PIGMENT IS OF LOW N BASED ON THE RESULTS OF A 90-DAY FEEDING STUDY IN RATS AND DOGS. MALES MALES (4/SEX/DOSE) WERE FED 2000, 5000 AND 20000 PPM, EQUIVALENT TO 50, D 500 MG/KG/DAY. NO TREATMENT-RELATED TUMORS DEVELOPED IN THE ANIMALS. UDY WAS LIMITED TO HIGH MORTALITY AT 5000 PPM (EXCEPT MEDIUM CHROME AND LIGHT CHROME YELLOW) AND 20000 PPM. OGENICITY CANNOT BE DETERMINED BASED ON SUBCUTANEOUS INJECTION OF LEAD TE. RATS EXPOSED TO LEAD CHROMATE AS CHROMIUM YELLOW OR CHROMIUM ORANGE T DEVELOPED TUMORS (UNSPECIFIED TYPE); INCIDENCE WAS 26/40 WITH BOTH TS). NO OTHER DETAILS WERE PROVIDED. CARCINOGENICITY CANNOT BE INED BASED ON INHALATION (OCCUPATIONAL) EXPOSURE TO LEAD CHROMATE TS IN HUMANS. WORKERS EXPOSED TO LEAD CHROMATE PIGMENTS HAVE SLIGHT IN INCIDENCE OF LUNG CANCER. THE STUDY IS LIMITED BECAUSE THE WORKERS VE BEEN EXPOSED ONLY TO ZINC CHROMATE OR TO DUST COMPOSED OF MIXTURES OF ND ZINC CHROMATE PIGMENTS. RPORATE TOXICOLOGISTS PRESENTED A SUMMARY OF TOXICOLOGICAL EFFECTS T TO EXIST AT THE TIME (1981) FOR LEAD CHROMATES, BASED ON ANIMAL AND OBSERVATIONAL STUDIES, THE LATTER MOSTLY MORTALITY STUDIES OF WORKER S IN SEVERAL COUNTRIES. VERY LITTLE SYSTEMATIC DATA WERE PRESENTED, AN OVERALL QUALITATIVE INTERPRETATION (E.G., MANUFACTURE OF LEAD AND HROMATE PIGMENTS WERE ASSOCIATED WITH AN APPROXIMATE 2-FOLD LUNG CANCER AND DUST CONCENTRATIONS WERE AN IMPORTANT FACTOR). THE COMPARATIVE S CITED SHOW LUNG CANCER RISKS IN CHROMATE ORE PROCESSING PLANTS WAS THAN IN THE PIGMENTS INDUSTRY."
1577129,Corporation 1992,Subchronic toxicity,"RATS (ALBINO) WERE ADMINSTERED ORALLY ENCAPSULATED MEDIUM CHROME YELLOW IN AT 2000, 5000 AND 20000 PPM FOR 90 DAYS (2 STUDIES). THE TOXICITY ED MAINLY AT THE HIGH DOSE, INCLUDED REDUCED HEMOGLOBIN CONCENTRATION AND LEUKOCYTES IN MALES AND REDUCED HEMATOCRIT IN BOTH GENDERS, RENAL LESIONS HIGH DOSE GROUP. THE LEAD AND CHROMIUM CONTENT INCREASED IN DEEP TISSUE KIDNEY AND LIVER.","Subchronic toxicity Abs: RATS (ALBINO) WERE ADMINSTERED ORALLY ENCAPSULATED MEDIUM CHROME YELLOW IN AT 2000, 5000 AND 20000 PPM FOR 90 DAYS (2 STUDIES). THE TOXICITY ED MAINLY AT THE HIGH DOSE, INCLUDED REDUCED HEMOGLOBIN CONCENTRATION AND LEUKOCYTES IN MALES AND REDUCED HEMATOCRIT IN BOTH GENDERS, RENAL LESIONS HIGH DOSE GROUP. THE LEAD AND CHROMIUM CONTENT INCREASED IN DEEP TISSUE KIDNEY AND LIVER."
1577128,Chiang and  Athanasopoulos 1994,"Nonchromate, Low Density, Waterborne Epoxy Primer, Tri-Service Committee on Corrosion Proceedings","A chrome-free, low density, waterborne epoxy primer was developed to meet MIL-P-85582B Specification. This primer does not contain toxic pigments and provides comparable corrosion protection as strontium chromate counterparts. Its dry film density was calculated at 0.0073 lbs/mil/square ft. It can be top coated with MIL-C-83286 and MIL-C-85285 urethane coatings within an hour at 77 deg F and 50% RH.","Nonchromate, Low Density, Waterborne Epoxy Primer, Tri-Service Committee on Corrosion Proceedings Abs: A chrome-free, low density, waterborne epoxy primer was developed to meet MIL-P-85582B Specification. This primer does not contain toxic pigments and provides comparable corrosion protection as strontium chromate counterparts. Its dry film density was calculated at 0.0073 lbs/mil/square ft. It can be top coated with MIL-C-83286 and MIL-C-85285 urethane coatings within an hour at 77 deg F and 50% RH."
1577127,Wander et al. 2001,Comparison of Time-Averaged Concentrations Measured at Fixed Locations and Painters' Breathing Zones During Aircraft Spray Painting in Conditions of Straight-Through and Recirculating Ventilation,"Meeting abstract rept.1 Sept 1999-31 May 2001. e Industrial Hygiene exposure sampling was conducted during application of prime and top coats to C-130 aircraft in a ventilated insert located in Building 270, Hill Air Force Base. Equivalent sets of measurements were taken by staff of the Bioenvironmental Engineering office for each of three aircraft, one of which was painted under conditions of 80% recirculation of filtered painting exhaust air. Typically large scatter was evident both within and among the data sets so generated, but the set of exposure measurements taken in the recirculated environment was not significantly elevated relative to the two sets measured in staright-through conditions. Toxicants measured were butyl acetate, diisobutyl ketone, ethylbenzene, methyl amyl ketone, methyl propyl ketone, xylene, hexamethylene diisocyanate (HDl), toluene 2,4-diisocyanate (TDl) , and strontium chromate.","Comparison of Time-Averaged Concentrations Measured at Fixed Locations and Painters' Breathing Zones During Aircraft Spray Painting in Conditions of Straight-Through and Recirculating Ventilation Abs: Meeting abstract rept.1 Sept 1999-31 May 2001. e Industrial Hygiene exposure sampling was conducted during application of prime and top coats to C-130 aircraft in a ventilated insert located in Building 270, Hill Air Force Base. Equivalent sets of measurements were taken by staff of the Bioenvironmental Engineering office for each of three aircraft, one of which was painted under conditions of 80% recirculation of filtered painting exhaust air. Typically large scatter was evident both within and among the data sets so generated, but the set of exposure measurements taken in the recirculated environment was not significantly elevated relative to the two sets measured in staright-through conditions. Toxicants measured were butyl acetate, diisobutyl ketone, ethylbenzene, methyl amyl ketone, methyl propyl ketone, xylene, hexamethylene diisocyanate (HDl), toluene 2,4-diisocyanate (TDl) , and strontium chromate."
1577126,Strum 2000,"User's Guide for the Emissions Modeling System for Hazardous Air Pollutants (EMS-HAP, Version 1.1)","The Emissions Modeling System for Hazardous Air Pollutants (EMS-HAP) is a series of computer programs that process emission inventory data for subsequent air quality modeling. EMS-HAP accomplishes two goals: (1) It processes an emission inventory, such as the 1996 National Toxics Inventory, for use in the Assessment System for Population Exposure Nationwide (ASPEN) dispersion model. (2) It allows you to estimate future-year emissions data for use in the ASPEN dispersion model. To accomplish the first goal, EMS-HAP: quality assures point source inventory location and stack parameter data and defaults missing or erroneous data where possible, groups and/or partitions individual pollutant species (e.g., groups lead oxide, lead nitrate into a lead groups; partitions lead chromate into lead and chromium groups), facilitates the selection of pollutants and pollutant groups for modeling, spatially locates county-level area and mobile source emissions to the census tract level using spatial surrogates such as population, allocates county-level aircraft emissions to airport locations, temporally allocates annual emission rates to annually averaged (i.e., same rate for every day of the year) 3-hour emission rates based on the type of source, and, produces emission files formatted for direct input into the ASPEN model.","User's Guide for the Emissions Modeling System for Hazardous Air Pollutants (EMS-HAP, Version 1.1) Abs: The Emissions Modeling System for Hazardous Air Pollutants (EMS-HAP) is a series of computer programs that process emission inventory data for subsequent air quality modeling. EMS-HAP accomplishes two goals: (1) It processes an emission inventory, such as the 1996 National Toxics Inventory, for use in the Assessment System for Population Exposure Nationwide (ASPEN) dispersion model. (2) It allows you to estimate future-year emissions data for use in the ASPEN dispersion model. To accomplish the first goal, EMS-HAP: quality assures point source inventory location and stack parameter data and defaults missing or erroneous data where possible, groups and/or partitions individual pollutant species (e.g., groups lead oxide, lead nitrate into a lead groups; partitions lead chromate into lead and chromium groups), facilitates the selection of pollutants and pollutant groups for modeling, spatially locates county-level area and mobile source emissions to the census tract level using spatial surrogates such as population, allocates county-level aircraft emissions to airport locations, temporally allocates annual emission rates to annually averaged (i.e., same rate for every day of the year) 3-hour emission rates based on the type of source, and, produces emission files formatted for direct input into the ASPEN model."
1577125,Poret et al. 2012,Environmentally Benign Pyrotechnic Delays,"Pyrotechnic delays are used in commercial and military items requiring a time delay between two energetic events. For example, US Army hand- held signals (HHS) use a delay element to properly sequence the expulsion of illuminating rounds at the rockets' apex. Many military delay formulations contain barium, lead, chromates, and perchlorates. The US Army is reformulating pyrotechnic items to remove environmentally hazardous materials. In this paper, new environmentally benign formulations are described. The delay time of the new system is easily tunable. These compositions will consistently function in aluminum housings which is generally difficult for delay compositions due to extreme thermal losses that can cause quenching.","Environmentally Benign Pyrotechnic Delays Abs: Pyrotechnic delays are used in commercial and military items requiring a time delay between two energetic events. For example, US Army hand- held signals (HHS) use a delay element to properly sequence the expulsion of illuminating rounds at the rockets' apex. Many military delay formulations contain barium, lead, chromates, and perchlorates. The US Army is reformulating pyrotechnic items to remove environmentally hazardous materials. In this paper, new environmentally benign formulations are described. The delay time of the new system is easily tunable. These compositions will consistently function in aluminum housings which is generally difficult for delay compositions due to extreme thermal losses that can cause quenching."
1577124,Morgan 2000,Chromate Dissociation from Primer Paint in Simulated Lung Fluid,"Master's Thesis. as proposed a new strontium chromate exposure standard that would potentially cause Air Force paint facilities to be in violation of the proposed standard if adopted. This proposed reduction makes the continued use of chromate containing primer paints very difficult. There is currently no acceptable replacements for chromate containing primer paints on AF aircraft. This study suggests that paint particles with chromate bound in primer paint may be unavailable for bodily absorption if inhaled and a reduced standard for painting applications may be unnecessary. Primer paint overspray was collected into simulated lung fluid (SLF) and allowed 6 hr, 24 hr, and 48 hr contact time in the SLF. At each residence time, particles were filtered Out and the dissolved chromate concentrations were quantified. The fraction of chromate dissolved was them compared to the total chromate originally collected. The results of this experiment imply that residence time in SLF does not affect dissociation. Results of the dissociation of chromate in primer paint particles implies the chromate dissociation may be hindered.","Chromate Dissociation from Primer Paint in Simulated Lung Fluid Abs: Master's Thesis. as proposed a new strontium chromate exposure standard that would potentially cause Air Force paint facilities to be in violation of the proposed standard if adopted. This proposed reduction makes the continued use of chromate containing primer paints very difficult. There is currently no acceptable replacements for chromate containing primer paints on AF aircraft. This study suggests that paint particles with chromate bound in primer paint may be unavailable for bodily absorption if inhaled and a reduced standard for painting applications may be unnecessary. Primer paint overspray was collected into simulated lung fluid (SLF) and allowed 6 hr, 24 hr, and 48 hr contact time in the SLF. At each residence time, particles were filtered Out and the dissolved chromate concentrations were quantified. The fraction of chromate dissolved was them compared to the total chromate originally collected. The results of this experiment imply that residence time in SLF does not affect dissociation. Results of the dissociation of chromate in primer paint particles implies the chromate dissociation may be hindered."
1577123,Leal et al. 1995,"Zero Discharge Organic Coatings, Powder Paint - UV Curable Paint - E-Coat. Volume 1","Final rept. Jun 93-Jun 95. 156. ischarge Organic Coatings project developed powder paint, Ultraviolet (UV) curable paint, and electro- coating (E-coat) paint for military Applications. These technologies offer potential for high performance coatings with little or no volatile organic compound (VOC) emissions or hazardous waste generation. The ZDOC project focused on formulating non-toxic corrosion inhibitors into these coating technologies, and the applications development of powder coatings. Non-toxic replacements for traditional lead and chromate inhibitors were selected based on a previous NAWCADWAR investigation. Once incorporated, the performance of the coatings with and without inhibitors was compared. Also, the protective mechanisms of these inhibitors were studied. The applications development for powder coatings analyzed technologies to allow powder coating of non-conductive substrates and evaluated the use of IR energy to cure powder coatings. Inhibitors were successfully incorporated into electrocoatings and powder coatings, however corrosion performance results varied with coating formulation. jg p. 2.","Zero Discharge Organic Coatings, Powder Paint - UV Curable Paint - E-Coat. Volume 1 Abs: Final rept. Jun 93-Jun 95. 156. ischarge Organic Coatings project developed powder paint, Ultraviolet (UV) curable paint, and electro- coating (E-coat) paint for military Applications. These technologies offer potential for high performance coatings with little or no volatile organic compound (VOC) emissions or hazardous waste generation. The ZDOC project focused on formulating non-toxic corrosion inhibitors into these coating technologies, and the applications development of powder coatings. Non-toxic replacements for traditional lead and chromate inhibitors were selected based on a previous NAWCADWAR investigation. Once incorporated, the performance of the coatings with and without inhibitors was compared. Also, the protective mechanisms of these inhibitors were studied. The applications development for powder coatings analyzed technologies to allow powder coating of non-conductive substrates and evaluated the use of IR energy to cure powder coatings. Inhibitors were successfully incorporated into electrocoatings and powder coatings, however corrosion performance results varied with coating formulation. jg p. 2."
1577122,Lapuma 1998,Recirculating Industrial Air: The Impact on Air Compliance and Workers; Safety Case Study: Hill Air Force Base C-130 Painting Operations,"Doctoral thesis. 90 Clean Air Act Amendment resulted in new environmental regulations called the National Emission Standards for Hazardous Air Pollutants (NESHAPs). Industries such as painting facilities may have to treat large volumes of air, which drives the cost of an air control system. Recirculating a portion of the air back into the facility is an option to reduce the amount of air to be treated. A guided computer model written in Microsoft Excel 97% is developed to analyze worker safety and compliance costs with a focus on recirculation. The model has a chemical database containing over 1300 chemicals and requires inputs such as tasks performed, hazardous products used, and chemical make-up of the products. The model will predict indoor air concentrations in relation to occupational exposure limits (OELs). A case study is performed on a C-1 30 aircraft painting facility at Hill AFB, UT. The Aerospace NESHAP requires air pollution reductions in aircraft painting operations. The model predicts strontium chromate concentrations found in primer paints will reach 1000 times the OEL. Strontium chromate and other solid particulates &amp;nearly unaffected by recirculation because the air is filtered prior to recirculation. The next highest chemical, hexamethylene diisocyanate (HDI), increases from 2.6 to 10.5 times the OEL at 0% and 75% recirculation, respectively. Due to the level of respiratory protection required for the strontium chromate, workers &amp;well protected from the modest increases in concentrations caused by recirculating 75%. The initial cost of a VOC control system with no recirculation is $4.5 million and $1.8 million at 75% recirculation. To decide the best operating conditions for a facility, all options such as product substitution, operational changes or recirculation should be explored. The model is an excellent tool to evaluate these options.","Recirculating Industrial Air: The Impact on Air Compliance and Workers; Safety Case Study: Hill Air Force Base C-130 Painting Operations Abs: Doctoral thesis. 90 Clean Air Act Amendment resulted in new environmental regulations called the National Emission Standards for Hazardous Air Pollutants (NESHAPs). Industries such as painting facilities may have to treat large volumes of air, which drives the cost of an air control system. Recirculating a portion of the air back into the facility is an option to reduce the amount of air to be treated. A guided computer model written in Microsoft Excel 97% is developed to analyze worker safety and compliance costs with a focus on recirculation. The model has a chemical database containing over 1300 chemicals and requires inputs such as tasks performed, hazardous products used, and chemical make-up of the products. The model will predict indoor air concentrations in relation to occupational exposure limits (OELs). A case study is performed on a C-1 30 aircraft painting facility at Hill AFB, UT. The Aerospace NESHAP requires air pollution reductions in aircraft painting operations. The model predicts strontium chromate concentrations found in primer paints will reach 1000 times the OEL. Strontium chromate and other solid particulates &amp;nearly unaffected by recirculation because the air is filtered prior to recirculation. The next highest chemical, hexamethylene diisocyanate (HDI), increases from 2.6 to 10.5 times the OEL at 0% and 75% recirculation, respectively. Due to the level of respiratory protection required for the strontium chromate, workers &amp;well protected from the modest increases in concentrations caused by recirculating 75%. The initial cost of a VOC control system with no recirculation is $4.5 million and $1.8 million at 75% recirculation. To decide the best operating conditions for a facility, all options such as product substitution, operational changes or recirculation should be explored. The model is an excellent tool to evaluate these options."
1577116,Zhitkovich 2005,Genotoxicity of Chromium Compounds,"DESCRIPTION (provided by applicant): Carcinogenic activity of hexavalent chromium (Cr) compounds is firmly established by experimental and epidemiological studies. Human exposure to Cr(VI) is found in several dozen occupations and detected in populations residing in the vicinity of Cr-emitting industrial sources and Cr disposal sites. Cr(Vl) is a major air pollutant and a Superfund contaminant. The major form of DNA damage in Cr(VI)-exposed cells is abundant Cr-DNA adducts generated in the reactions of stable Cr(III) form with DNA phosphates. We have found that several Cr-DNA adducts were mutagenic during replication in human cells. Ternary DNA adducts containing bulky ligands, such as glutathione or ascorbate, induced the strongest mutagenic responses. We also determined that Cr(III)-dependent reactions were responsible for the formation of mutagenic DNA damage during reductive activation of Cr(VI) by its major biological reducers, cysteine and ascorbate. Additional data have shown that biological consequences of the formation of Cr(III)-DNA adducts are strongly influenced by the status of DNA mismatch repair system. We propose to elucidate the mechanisms of mismatch repair-dependent induction of stress signaling and formation of genetic alterations in Cr(VI)- exposed cells. Experiments will be performed to identify specific Cr-DNA adducts that are recognized by DNA mismatch repair and activate genotoxic responses. The results of this work should provide a greater understanding of molecular basis of Cr(VI) carcinogenesis, the importance of individual Cr-DNA adducts and uncover new functions of mismatch repair in recognition of DNA backbone modifications. Identification of the most potent genotoxic Cr-DNA adducts and critical pathways controlling cellular responses to Cr(VI) can be used in the development of useful biomarkers of exposure and individual susceptibility to adverse health effects.","Genotoxicity of Chromium Compounds Abs: DESCRIPTION (provided by applicant): Carcinogenic activity of hexavalent chromium (Cr) compounds is firmly established by experimental and epidemiological studies. Human exposure to Cr(VI) is found in several dozen occupations and detected in populations residing in the vicinity of Cr-emitting industrial sources and Cr disposal sites. Cr(Vl) is a major air pollutant and a Superfund contaminant. The major form of DNA damage in Cr(VI)-exposed cells is abundant Cr-DNA adducts generated in the reactions of stable Cr(III) form with DNA phosphates. We have found that several Cr-DNA adducts were mutagenic during replication in human cells. Ternary DNA adducts containing bulky ligands, such as glutathione or ascorbate, induced the strongest mutagenic responses. We also determined that Cr(III)-dependent reactions were responsible for the formation of mutagenic DNA damage during reductive activation of Cr(VI) by its major biological reducers, cysteine and ascorbate. Additional data have shown that biological consequences of the formation of Cr(III)-DNA adducts are strongly influenced by the status of DNA mismatch repair system. We propose to elucidate the mechanisms of mismatch repair-dependent induction of stress signaling and formation of genetic alterations in Cr(VI)- exposed cells. Experiments will be performed to identify specific Cr-DNA adducts that are recognized by DNA mismatch repair and activate genotoxic responses. The results of this work should provide a greater understanding of molecular basis of Cr(VI) carcinogenesis, the importance of individual Cr-DNA adducts and uncover new functions of mismatch repair in recognition of DNA backbone modifications. Identification of the most potent genotoxic Cr-DNA adducts and critical pathways controlling cellular responses to Cr(VI) can be used in the development of useful biomarkers of exposure and individual susceptibility to adverse health effects."
1577115,Zhitkovich 2004,Genotoxicity of Chromium Compounds,"DESCRIPTION (provided by applicant): Carcinogenic activity of hexavalent chromium (Cr) compounds is firmly established by experimental and epidemiological studies. Human exposure to Cr(VI) is found in several dozen occupations and detected in populations residing in the vicinity of Cr-emitting industrial sources and Cr disposal sites. Cr(Vl) is a major air pollutant and a Superfund contaminant. The major form of DNA damage in Cr(VI)-exposed cells is abundant Cr-DNA adducts generated in the reactions of stable Cr(III) form with DNA phosphates. We have found that several Cr-DNA adducts were mutagenic during replication in human cells. Ternary DNA adducts containing bulky ligands, such as glutathione or ascorbate, induced the strongest mutagenic responses. We also determined that Cr(III)-dependent reactions were responsible for the formation of mutagenic DNA damage during reductive activation of Cr(VI) by its major biological reducers, cysteine and ascorbate. Additional data have shown that biological consequences of the formation of Cr(III)-DNA adducts are strongly influenced by the status of DNA mismatch repair system. We propose to elucidate the mechanisms of mismatch repair-dependent induction of stress signaling and formation of genetic alterations in Cr(VI)- exposed cells. Experiments will be performed to identify specific Cr-DNA adducts that are recognized by DNA mismatch repair and activate genotoxic responses. The results of this work should provide a greater understanding of molecular basis of Cr(VI) carcinogenesis, the importance of individual Cr-DNA adducts and uncover new functions of mismatch repair in recognition of DNA backbone modifications. Identification of the most potent genotoxic Cr-DNA adducts and critical pathways controlling cellular responses to Cr(VI) can be used in the development of useful biomarkers of exposure and individual susceptibility to adverse health effects.","Genotoxicity of Chromium Compounds Abs: DESCRIPTION (provided by applicant): Carcinogenic activity of hexavalent chromium (Cr) compounds is firmly established by experimental and epidemiological studies. Human exposure to Cr(VI) is found in several dozen occupations and detected in populations residing in the vicinity of Cr-emitting industrial sources and Cr disposal sites. Cr(Vl) is a major air pollutant and a Superfund contaminant. The major form of DNA damage in Cr(VI)-exposed cells is abundant Cr-DNA adducts generated in the reactions of stable Cr(III) form with DNA phosphates. We have found that several Cr-DNA adducts were mutagenic during replication in human cells. Ternary DNA adducts containing bulky ligands, such as glutathione or ascorbate, induced the strongest mutagenic responses. We also determined that Cr(III)-dependent reactions were responsible for the formation of mutagenic DNA damage during reductive activation of Cr(VI) by its major biological reducers, cysteine and ascorbate. Additional data have shown that biological consequences of the formation of Cr(III)-DNA adducts are strongly influenced by the status of DNA mismatch repair system. We propose to elucidate the mechanisms of mismatch repair-dependent induction of stress signaling and formation of genetic alterations in Cr(VI)- exposed cells. Experiments will be performed to identify specific Cr-DNA adducts that are recognized by DNA mismatch repair and activate genotoxic responses. The results of this work should provide a greater understanding of molecular basis of Cr(VI) carcinogenesis, the importance of individual Cr-DNA adducts and uncover new functions of mismatch repair in recognition of DNA backbone modifications. Identification of the most potent genotoxic Cr-DNA adducts and critical pathways controlling cellular responses to Cr(VI) can be used in the development of useful biomarkers of exposure and individual susceptibility to adverse health effects."
1577114,Zhitkovich 2004,Sensitivity Mechanisms in Chromium Toxicity,"DESCRIPTION (provided by applicant): Hexavalent chromium (CrVI) is a toxic DNA-damaging agent with a well-documented exposure in a large number of occupations, and it is a common environmental contaminant. Cr(VI) is listed by the ATSDR and EPA as one of the top 20 high priority toxic agents. The final oxidative form of Cr in biological systems is Cr(lll) that produces several stable DNA adducts. We have recently found that Cr(III)-DNA adducts are one of the major causes of mutagenicity of Cr(VI). Our new data indicate that Cr-DNA adducts also play an important role in toxicity of Cr(VI). Toxic responses to Cr-DNA adducts were strongly dependent on the presence of a small group of proteins that bind to Cr-damaged chromatin. This proposal is designed to test our working hypothesis that cytotoxic effects of Cr-DNA adducts are caused by the formation of secondary DNA lesions generated as a result of the recognition and processing of adducts by damage sensory proteins. Biochemical approaches and cellular models with downregulated levels of damage-processing proteins will be used to gain evidence supporting the proposed hypothesis. We constructed a series of the retroviral siRNA-encoding vectors, which will allow us to examine the role of various proteins in the cytotoxic responses in the target primary human bronchial epithelial cells that have not been previously amenable to the mechanistic studies. The results of this work are expected to advance molecular understanding of Cr(VI) injury in the major target cells and to identify damage processing proteins that enhance toxicity of Cr-DNA modifications.","Sensitivity Mechanisms in Chromium Toxicity Abs: DESCRIPTION (provided by applicant): Hexavalent chromium (CrVI) is a toxic DNA-damaging agent with a well-documented exposure in a large number of occupations, and it is a common environmental contaminant. Cr(VI) is listed by the ATSDR and EPA as one of the top 20 high priority toxic agents. The final oxidative form of Cr in biological systems is Cr(lll) that produces several stable DNA adducts. We have recently found that Cr(III)-DNA adducts are one of the major causes of mutagenicity of Cr(VI). Our new data indicate that Cr-DNA adducts also play an important role in toxicity of Cr(VI). Toxic responses to Cr-DNA adducts were strongly dependent on the presence of a small group of proteins that bind to Cr-damaged chromatin. This proposal is designed to test our working hypothesis that cytotoxic effects of Cr-DNA adducts are caused by the formation of secondary DNA lesions generated as a result of the recognition and processing of adducts by damage sensory proteins. Biochemical approaches and cellular models with downregulated levels of damage-processing proteins will be used to gain evidence supporting the proposed hypothesis. We constructed a series of the retroviral siRNA-encoding vectors, which will allow us to examine the role of various proteins in the cytotoxic responses in the target primary human bronchial epithelial cells that have not been previously amenable to the mechanistic studies. The results of this work are expected to advance molecular understanding of Cr(VI) injury in the major target cells and to identify damage processing proteins that enhance toxicity of Cr-DNA modifications."
1577113,Zhitkovich 2003,Genotoxicity of Chromium Compounds,"DESCRIPTION (provided by applicant): Carcinogenic activity of hexavalent chromium (Cr) compounds is firmly established by experimental and epidemiological studies. Human exposure to Cr(VI) is found in several dozen occupations and detected in populations residing in the vicinity of Cr-emitting industrial sources and Cr disposal sites. Cr(Vl) is a major air pollutant and a Superfund contaminant. The major form of DNA damage in Cr(VI)-exposed cells is abundant Cr-DNA adducts generated in the reactions of stable Cr(III) form with DNA phosphates. We have found that several Cr-DNA adducts were mutagenic during replication in human cells. Ternary DNA adducts containing bulky ligands, such as glutathione or ascorbate, induced the strongest mutagenic responses. We also determined that Cr(III)-dependent reactions were responsible for the formation of mutagenic DNA damage during reductive activation of Cr(VI) by its major biological reducers, cysteine and ascorbate. Additional data have shown that biological consequences of the formation of Cr(III)-DNA adducts are strongly influenced by the status of DNA mismatch repair system. We propose to elucidate the mechanisms of mismatch repair-dependent induction of stress signaling and formation of genetic alterations in Cr(VI)- exposed cells. Experiments will be performed to identify specific Cr-DNA adducts that are recognized by DNA mismatch repair and activate genotoxic responses. The results of this work should provide a greater understanding of molecular basis of Cr(VI) carcinogenesis, the importance of individual Cr-DNA adducts and uncover new functions of mismatch repair in recognition of DNA backbone modifications. Identification of the most potent genotoxic Cr-DNA adducts and critical pathways controlling cellular responses to Cr(VI) can be used in the development of useful biomarkers of exposure and individual susceptibility to adverse health effects.","Genotoxicity of Chromium Compounds Abs: DESCRIPTION (provided by applicant): Carcinogenic activity of hexavalent chromium (Cr) compounds is firmly established by experimental and epidemiological studies. Human exposure to Cr(VI) is found in several dozen occupations and detected in populations residing in the vicinity of Cr-emitting industrial sources and Cr disposal sites. Cr(Vl) is a major air pollutant and a Superfund contaminant. The major form of DNA damage in Cr(VI)-exposed cells is abundant Cr-DNA adducts generated in the reactions of stable Cr(III) form with DNA phosphates. We have found that several Cr-DNA adducts were mutagenic during replication in human cells. Ternary DNA adducts containing bulky ligands, such as glutathione or ascorbate, induced the strongest mutagenic responses. We also determined that Cr(III)-dependent reactions were responsible for the formation of mutagenic DNA damage during reductive activation of Cr(VI) by its major biological reducers, cysteine and ascorbate. Additional data have shown that biological consequences of the formation of Cr(III)-DNA adducts are strongly influenced by the status of DNA mismatch repair system. We propose to elucidate the mechanisms of mismatch repair-dependent induction of stress signaling and formation of genetic alterations in Cr(VI)- exposed cells. Experiments will be performed to identify specific Cr-DNA adducts that are recognized by DNA mismatch repair and activate genotoxic responses. The results of this work should provide a greater understanding of molecular basis of Cr(VI) carcinogenesis, the importance of individual Cr-DNA adducts and uncover new functions of mismatch repair in recognition of DNA backbone modifications. Identification of the most potent genotoxic Cr-DNA adducts and critical pathways controlling cellular responses to Cr(VI) can be used in the development of useful biomarkers of exposure and individual susceptibility to adverse health effects."
1577112,Zhitkovich 2001,GENOTOXICITY OF CHROMIUM COMPOUNDS,"DESCRIPTION: Exposure to hexavalent chromium compounds has been established to present a significant cancer risk to human respiratory system. Induction of DNA lesions and subsequently, mutations is generally considered to be responsible for the initiation of Cr(VI)-dependent carcinogenic process. Cr(VI) compounds have been shown to be mutagenic to bacterial and mammalian cells, however, the nature of underlying DNA modifications have not yet been characterized. Reductive conversion of Cr(VI) to Cr(III) accompanied by the formation of intermediate Cr(V/VI) forms and radical byproducts is required for the induction of genotoxic effects. Recent data showed that a major form of DNA adducts formed in Cr(VI)-exposed cells is represented by crosslinks composed of intracellular amino acids or glutathione bridged to DNA by Cr(III). Cysteine, histidine and glutamic acid were predominant amino acids found crosslinked to DNA. Subsequent in vitro studies demonstrated that these ternary adducts are formed by binding of Cr(III)-amino acid complexes to DNA. In preliminary experiments some amino acid-Cr(III) adducts exhibited mutagenic activity. On the basis of these data Dr. Zhitkovich hypothesized that a significant portion of Cr(VI) genotoxicity results from reactions of its final reductive metabolite, Cr(III). In order to obtain evidence supporting this hypothesis, a number of experiments aimed at studying formation of Cr(III) adducts and their mutagenic potential will be carried out. Mutagenicity of the in vitro formed Cr(III)- and amino acids/glutathione-Cr(III)-DNA adducts will be investigated in human cells using a shuttle vector approach. Involvement of Cr(III) in the DNA adduction in vivo will be studied in mammalian cells following their exposure to Cr(VI) or particulate Cr(III) compounds. In addition, the role of nucleotide excision repair in the removal of different Cr(III) adducts will also be analyzed. The results of the proposed work will help understand molecular mechanisms of Cr(VI) carcinogenicity by testing a Cr(III)-dependent pathway of DNA damage and mutagenicity of major adducts. Clarification of the genotoxic activity of intracellular Cr(III) may also have important public health implications considering the fact that human exposure frequently occurs to mixtures of Cr(VI) and Cr(III) forms while current risk assessment is based predominantly on the Cr(VI) levels.","GENOTOXICITY OF CHROMIUM COMPOUNDS Abs: DESCRIPTION: Exposure to hexavalent chromium compounds has been established to present a significant cancer risk to human respiratory system. Induction of DNA lesions and subsequently, mutations is generally considered to be responsible for the initiation of Cr(VI)-dependent carcinogenic process. Cr(VI) compounds have been shown to be mutagenic to bacterial and mammalian cells, however, the nature of underlying DNA modifications have not yet been characterized. Reductive conversion of Cr(VI) to Cr(III) accompanied by the formation of intermediate Cr(V/VI) forms and radical byproducts is required for the induction of genotoxic effects. Recent data showed that a major form of DNA adducts formed in Cr(VI)-exposed cells is represented by crosslinks composed of intracellular amino acids or glutathione bridged to DNA by Cr(III). Cysteine, histidine and glutamic acid were predominant amino acids found crosslinked to DNA. Subsequent in vitro studies demonstrated that these ternary adducts are formed by binding of Cr(III)-amino acid complexes to DNA. In preliminary experiments some amino acid-Cr(III) adducts exhibited mutagenic activity. On the basis of these data Dr. Zhitkovich hypothesized that a significant portion of Cr(VI) genotoxicity results from reactions of its final reductive metabolite, Cr(III). In order to obtain evidence supporting this hypothesis, a number of experiments aimed at studying formation of Cr(III) adducts and their mutagenic potential will be carried out. Mutagenicity of the in vitro formed Cr(III)- and amino acids/glutathione-Cr(III)-DNA adducts will be investigated in human cells using a shuttle vector approach. Involvement of Cr(III) in the DNA adduction in vivo will be studied in mammalian cells following their exposure to Cr(VI) or particulate Cr(III) compounds. In addition, the role of nucleotide excision repair in the removal of different Cr(III) adducts will also be analyzed. The results of the proposed work will help understand molecular mechanisms of Cr(VI) carcinogenicity by testing a Cr(III)-dependent pathway of DNA damage and mutagenicity of major adducts. Clarification of the genotoxic activity of intracellular Cr(III) may also have important public health implications considering the fact that human exposure frequently occurs to mixtures of Cr(VI) and Cr(III) forms while current risk assessment is based predominantly on the Cr(VI) levels."
1577111,Zhitkovich 2000,GENOTOXICITY OF CHROMIUM COMPOUNDS,"DESCRIPTION: Exposure to hexavalent chromium compounds has been established to present a significant cancer risk to human respiratory system. Induction of DNA lesions and subsequently, mutations is generally considered to be responsible for the initiation of Cr(VI)-dependent carcinogenic process. Cr(VI) compounds have been shown to be mutagenic to bacterial and mammalian cells, however, the nature of underlying DNA modifications have not yet been characterized. Reductive conversion of Cr(VI) to Cr(III) accompanied by the formation of intermediate Cr(V/VI) forms and radical byproducts is required for the induction of genotoxic effects. Recent data showed that a major form of DNA adducts formed in Cr(VI)-exposed cells is represented by crosslinks composed of intracellular amino acids or glutathione bridged to DNA by Cr(III). Cysteine, histidine and glutamic acid were predominant amino acids found crosslinked to DNA. Subsequent in vitro studies demonstrated that these ternary adducts are formed by binding of Cr(III)-amino acid complexes to DNA. In preliminary experiments some amino acid-Cr(III) adducts exhibited mutagenic activity. On the basis of these data Dr. Zhitkovich hypothesized that a significant portion of Cr(VI) genotoxicity results from reactions of its final reductive metabolite, Cr(III). In order to obtain evidence supporting this hypothesis, a number of experiments aimed at studying formation of Cr(III) adducts and their mutagenic potential will be carried out. Mutagenicity of the in vitro formed Cr(III)- and amino acids/glutathione-Cr(III)-DNA adducts will be investigated in human cells using a shuttle vector approach. Involvement of Cr(III) in the DNA adduction in vivo will be studied in mammalian cells following their exposure to Cr(VI) or particulate Cr(III) compounds. In addition, the role of nucleotide excision repair in the removal of different Cr(III) adducts will also be analyzed. The results of the proposed work will help understand molecular mechanisms of Cr(VI) carcinogenicity by testing a Cr(III)-dependent pathway of DNA damage and mutagenicity of major adducts. Clarification of the genotoxic activity of intracellular Cr(III) may also have important public health implications considering the fact that human exposure frequently occurs to mixtures of Cr(VI) and Cr(III) forms while current risk assessment is based predominantly on the Cr(VI) levels.","GENOTOXICITY OF CHROMIUM COMPOUNDS Abs: DESCRIPTION: Exposure to hexavalent chromium compounds has been established to present a significant cancer risk to human respiratory system. Induction of DNA lesions and subsequently, mutations is generally considered to be responsible for the initiation of Cr(VI)-dependent carcinogenic process. Cr(VI) compounds have been shown to be mutagenic to bacterial and mammalian cells, however, the nature of underlying DNA modifications have not yet been characterized. Reductive conversion of Cr(VI) to Cr(III) accompanied by the formation of intermediate Cr(V/VI) forms and radical byproducts is required for the induction of genotoxic effects. Recent data showed that a major form of DNA adducts formed in Cr(VI)-exposed cells is represented by crosslinks composed of intracellular amino acids or glutathione bridged to DNA by Cr(III). Cysteine, histidine and glutamic acid were predominant amino acids found crosslinked to DNA. Subsequent in vitro studies demonstrated that these ternary adducts are formed by binding of Cr(III)-amino acid complexes to DNA. In preliminary experiments some amino acid-Cr(III) adducts exhibited mutagenic activity. On the basis of these data Dr. Zhitkovich hypothesized that a significant portion of Cr(VI) genotoxicity results from reactions of its final reductive metabolite, Cr(III). In order to obtain evidence supporting this hypothesis, a number of experiments aimed at studying formation of Cr(III) adducts and their mutagenic potential will be carried out. Mutagenicity of the in vitro formed Cr(III)- and amino acids/glutathione-Cr(III)-DNA adducts will be investigated in human cells using a shuttle vector approach. Involvement of Cr(III) in the DNA adduction in vivo will be studied in mammalian cells following their exposure to Cr(VI) or particulate Cr(III) compounds. In addition, the role of nucleotide excision repair in the removal of different Cr(III) adducts will also be analyzed. The results of the proposed work will help understand molecular mechanisms of Cr(VI) carcinogenicity by testing a Cr(III)-dependent pathway of DNA damage and mutagenicity of major adducts. Clarification of the genotoxic activity of intracellular Cr(III) may also have important public health implications considering the fact that human exposure frequently occurs to mixtures of Cr(VI) and Cr(III) forms while current risk assessment is based predominantly on the Cr(VI) levels."
1577110,Zhitkovich 1999,GENOTOXICITY OF CHROMIUM COMPOUNDS,"DESCRIPTION: Exposure to hexavalent chromium compounds has been established to present a significant cancer risk to human respiratory system. Induction of DNA lesions and subsequently, mutations is generally considered to be responsible for the initiation of Cr(VI)-dependent carcinogenic process. Cr(VI) compounds have been shown to be mutagenic to bacterial and mammalian cells, however, the nature of underlying DNA modifications have not yet been characterized. Reductive conversion of Cr(VI) to Cr(III) accompanied by the formation of intermediate Cr(V/VI) forms and radical byproducts is required for the induction of genotoxic effects. Recent data showed that a major form of DNA adducts formed in Cr(VI)-exposed cells is represented by crosslinks composed of intracellular amino acids or glutathione bridged to DNA by Cr(III). Cysteine, histidine and glutamic acid were predominant amino acids found crosslinked to DNA. Subsequent in vitro studies demonstrated that these ternary adducts are formed by binding of Cr(III)-amino acid complexes to DNA. In preliminary experiments some amino acid-Cr(III) adducts exhibited mutagenic activity. On the basis of these data Dr. Zhitkovich hypothesized that a significant portion of Cr(VI) genotoxicity results from reactions of its final reductive metabolite, Cr(III). In order to obtain evidence supporting this hypothesis, a number of experiments aimed at studying formation of Cr(III) adducts and their mutagenic potential will be carried out. Mutagenicity of the in vitro formed Cr(III)- and amino acids/glutathione-Cr(III)-DNA adducts will be investigated in human cells using a shuttle vector approach. Involvement of Cr(III) in the DNA adduction in vivo will be studied in mammalian cells following their exposure to Cr(VI) or particulate Cr(III) compounds. In addition, the role of nucleotide excision repair in the removal of different Cr(III) adducts will also be analyzed. The results of the proposed work will help understand molecular mechanisms of Cr(VI) carcinogenicity by testing a Cr(III)-dependent pathway of DNA damage and mutagenicity of major adducts. Clarification of the genotoxic activity of intracellular Cr(III) may also have important public health implications considering the fact that human exposure frequently occurs to mixtures of Cr(VI) and Cr(III) forms while current risk assessment is based predominantly on the Cr(VI) levels.","GENOTOXICITY OF CHROMIUM COMPOUNDS Abs: DESCRIPTION: Exposure to hexavalent chromium compounds has been established to present a significant cancer risk to human respiratory system. Induction of DNA lesions and subsequently, mutations is generally considered to be responsible for the initiation of Cr(VI)-dependent carcinogenic process. Cr(VI) compounds have been shown to be mutagenic to bacterial and mammalian cells, however, the nature of underlying DNA modifications have not yet been characterized. Reductive conversion of Cr(VI) to Cr(III) accompanied by the formation of intermediate Cr(V/VI) forms and radical byproducts is required for the induction of genotoxic effects. Recent data showed that a major form of DNA adducts formed in Cr(VI)-exposed cells is represented by crosslinks composed of intracellular amino acids or glutathione bridged to DNA by Cr(III). Cysteine, histidine and glutamic acid were predominant amino acids found crosslinked to DNA. Subsequent in vitro studies demonstrated that these ternary adducts are formed by binding of Cr(III)-amino acid complexes to DNA. In preliminary experiments some amino acid-Cr(III) adducts exhibited mutagenic activity. On the basis of these data Dr. Zhitkovich hypothesized that a significant portion of Cr(VI) genotoxicity results from reactions of its final reductive metabolite, Cr(III). In order to obtain evidence supporting this hypothesis, a number of experiments aimed at studying formation of Cr(III) adducts and their mutagenic potential will be carried out. Mutagenicity of the in vitro formed Cr(III)- and amino acids/glutathione-Cr(III)-DNA adducts will be investigated in human cells using a shuttle vector approach. Involvement of Cr(III) in the DNA adduction in vivo will be studied in mammalian cells following their exposure to Cr(VI) or particulate Cr(III) compounds. In addition, the role of nucleotide excision repair in the removal of different Cr(III) adducts will also be analyzed. The results of the proposed work will help understand molecular mechanisms of Cr(VI) carcinogenicity by testing a Cr(III)-dependent pathway of DNA damage and mutagenicity of major adducts. Clarification of the genotoxic activity of intracellular Cr(III) may also have important public health implications considering the fact that human exposure frequently occurs to mixtures of Cr(VI) and Cr(III) forms while current risk assessment is based predominantly on the Cr(VI) levels."
1577109,Zhitkovich 1998,GENOTOXICITY OF CHROMIUM COMPOUNDS,"DESCRIPTION: Exposure to hexavalent chromium compounds has been established to present a significant cancer risk to human respiratory system. Induction of DNA lesions and subsequently, mutations is generally considered to be responsible for the initiation of Cr(VI)-dependent carcinogenic process. Cr(VI) compounds have been shown to be mutagenic to bacterial and mammalian cells, however, the nature of underlying DNA modifications have not yet been characterized. Reductive conversion of Cr(VI) to Cr(III) accompanied by the formation of intermediate Cr(V/VI) forms and radical byproducts is required for the induction of genotoxic effects. Recent data showed that a major form of DNA adducts formed in Cr(VI)-exposed cells is represented by crosslinks composed of intracellular amino acids or glutathione bridged to DNA by Cr(III). Cysteine, histidine and glutamic acid were predominant amino acids found crosslinked to DNA. Subsequent in vitro studies demonstrated that these ternary adducts are formed by binding of Cr(III)-amino acid complexes to DNA. In preliminary experiments some amino acid-Cr(III) adducts exhibited mutagenic activity. On the basis of these data Dr. Zhitkovich hypothesized that a significant portion of Cr(VI) genotoxicity results from reactions of its final reductive metabolite, Cr(III). In order to obtain evidence supporting this hypothesis, a number of experiments aimed at studying formation of Cr(III) adducts and their mutagenic potential will be carried out. Mutagenicity of the in vitro formed Cr(III)- and amino acids/glutathione-Cr(III)-DNA adducts will be investigated in human cells using a shuttle vector approach. Involvement of Cr(III) in the DNA adduction in vivo will be studied in mammalian cells following their exposure to Cr(VI) or particulate Cr(III) compounds. In addition, the role of nucleotide excision repair in the removal of different Cr(III) adducts will also be analyzed. The results of the proposed work will help understand molecular mechanisms of Cr(VI) carcinogenicity by testing a Cr(III)-dependent pathway of DNA damage and mutagenicity of major adducts. Clarification of the genotoxic activity of intracellular Cr(III) may also have important public health implications considering the fact that human exposure frequently occurs to mixtures of Cr(VI) and Cr(III) forms while current risk assessment is based predominantly on the Cr(VI) levels.","GENOTOXICITY OF CHROMIUM COMPOUNDS Abs: DESCRIPTION: Exposure to hexavalent chromium compounds has been established to present a significant cancer risk to human respiratory system. Induction of DNA lesions and subsequently, mutations is generally considered to be responsible for the initiation of Cr(VI)-dependent carcinogenic process. Cr(VI) compounds have been shown to be mutagenic to bacterial and mammalian cells, however, the nature of underlying DNA modifications have not yet been characterized. Reductive conversion of Cr(VI) to Cr(III) accompanied by the formation of intermediate Cr(V/VI) forms and radical byproducts is required for the induction of genotoxic effects. Recent data showed that a major form of DNA adducts formed in Cr(VI)-exposed cells is represented by crosslinks composed of intracellular amino acids or glutathione bridged to DNA by Cr(III). Cysteine, histidine and glutamic acid were predominant amino acids found crosslinked to DNA. Subsequent in vitro studies demonstrated that these ternary adducts are formed by binding of Cr(III)-amino acid complexes to DNA. In preliminary experiments some amino acid-Cr(III) adducts exhibited mutagenic activity. On the basis of these data Dr. Zhitkovich hypothesized that a significant portion of Cr(VI) genotoxicity results from reactions of its final reductive metabolite, Cr(III). In order to obtain evidence supporting this hypothesis, a number of experiments aimed at studying formation of Cr(III) adducts and their mutagenic potential will be carried out. Mutagenicity of the in vitro formed Cr(III)- and amino acids/glutathione-Cr(III)-DNA adducts will be investigated in human cells using a shuttle vector approach. Involvement of Cr(III) in the DNA adduction in vivo will be studied in mammalian cells following their exposure to Cr(VI) or particulate Cr(III) compounds. In addition, the role of nucleotide excision repair in the removal of different Cr(III) adducts will also be analyzed. The results of the proposed work will help understand molecular mechanisms of Cr(VI) carcinogenicity by testing a Cr(III)-dependent pathway of DNA damage and mutagenicity of major adducts. Clarification of the genotoxic activity of intracellular Cr(III) may also have important public health implications considering the fact that human exposure frequently occurs to mixtures of Cr(VI) and Cr(III) forms while current risk assessment is based predominantly on the Cr(VI) levels."
1577108,Xu 2004,ATM and ATR in chromium-induced S-phase arrest,"DESCRIPTION (provided by applicant): Hexavalent chromium (Cr [VI]) is a common industrial waste product and an environmental pollutant, and it is a known human carcinogen. Cr (VI) compounds are metabolized to pentavalent (Cr [V]), tetravalent (Cr [IV]), and trivalent (Cr [III]) chromium once they enter the body. Cr (V) and Cr (IV) are highly reactive intermediates and have been shown to cause several types of DNA damage. Exposure to Cr compounds triggers the S-phase cell cycle checkpoint, an active cellular response which may enhance cell survival and limit heritable genetic abnormalities in the presence of DNA damage. Characterization of biochemical steps in Cr-induced S-phase arrest will help improve our understanding of mechanisms of Cr-induced tumorigenesis. The stimulus for proposing the experiments in this application is our preliminary observations that Ataxia-Telangiectasia-Mutated protein kinase (ATM) and its related kinase ATR are required for Cr-induced intra S-phase arrest. ATM and ATR belong to a structurally unique family of protein serine-threonine kinases whose catalytic domains share a clear evolutionary relationship with those of mammalian and yeast phosphoinositide 3-kinases. Both ATM and ATR are critical for cellular response to DNA damage. Our preliminary data has revealed that exposure to Cr (VI), and its metabolic byproducts Cr (V) and Cr (IV), induces measurable DNA double strand breaks. However, only Cr (V) and Cr (VI), but not Cr (IV), can activate intra S-phase checkpoint and ATM kinase. The Cr-induced S-phase arrest is both ATM- and ATR-dependent. Furthermore, we found that the Structural Maintenance of Chromosomal protein 1 (SMC 1) is phosphorylated in an ATM-dependent manner after low dose Cr exposure. The proposed experiments will investigate how ATM and ATR regulate S-phase arrest after exposure to Cr and identify molecular determinants of the process. In specific aim 1, we will investigate whether NBS 1 and BRCA1, both of which are ATM substrates in response to DNA damage, are required for the ATM-dependent process. We will also study the functional significance of ATM phosphorylation of SMC 1 in response to Cr exposure. In specific aim 2, we will study whether ATR is activated by exposure to Cr and whether SMC 1 is a downstream target of ATR in regulating the checkpoint. Our long-term goal is to better understand the mechanisms by which mammalian cells respond to Cr exposure and the role of ATM and ATR in the pathway as a basis for providing insights into general mechanisms of carcinogenesis, cell growth and cell death.","ATM and ATR in chromium-induced S-phase arrest Abs: DESCRIPTION (provided by applicant): Hexavalent chromium (Cr [VI]) is a common industrial waste product and an environmental pollutant, and it is a known human carcinogen. Cr (VI) compounds are metabolized to pentavalent (Cr [V]), tetravalent (Cr [IV]), and trivalent (Cr [III]) chromium once they enter the body. Cr (V) and Cr (IV) are highly reactive intermediates and have been shown to cause several types of DNA damage. Exposure to Cr compounds triggers the S-phase cell cycle checkpoint, an active cellular response which may enhance cell survival and limit heritable genetic abnormalities in the presence of DNA damage. Characterization of biochemical steps in Cr-induced S-phase arrest will help improve our understanding of mechanisms of Cr-induced tumorigenesis. The stimulus for proposing the experiments in this application is our preliminary observations that Ataxia-Telangiectasia-Mutated protein kinase (ATM) and its related kinase ATR are required for Cr-induced intra S-phase arrest. ATM and ATR belong to a structurally unique family of protein serine-threonine kinases whose catalytic domains share a clear evolutionary relationship with those of mammalian and yeast phosphoinositide 3-kinases. Both ATM and ATR are critical for cellular response to DNA damage. Our preliminary data has revealed that exposure to Cr (VI), and its metabolic byproducts Cr (V) and Cr (IV), induces measurable DNA double strand breaks. However, only Cr (V) and Cr (VI), but not Cr (IV), can activate intra S-phase checkpoint and ATM kinase. The Cr-induced S-phase arrest is both ATM- and ATR-dependent. Furthermore, we found that the Structural Maintenance of Chromosomal protein 1 (SMC 1) is phosphorylated in an ATM-dependent manner after low dose Cr exposure. The proposed experiments will investigate how ATM and ATR regulate S-phase arrest after exposure to Cr and identify molecular determinants of the process. In specific aim 1, we will investigate whether NBS 1 and BRCA1, both of which are ATM substrates in response to DNA damage, are required for the ATM-dependent process. We will also study the functional significance of ATM phosphorylation of SMC 1 in response to Cr exposure. In specific aim 2, we will study whether ATR is activated by exposure to Cr and whether SMC 1 is a downstream target of ATR in regulating the checkpoint. Our long-term goal is to better understand the mechanisms by which mammalian cells respond to Cr exposure and the role of ATM and ATR in the pathway as a basis for providing insights into general mechanisms of carcinogenesis, cell growth and cell death."
1577107,Wise 2004,Toxiology of Particulate Cr(VI)in Human Lung Cells,"Cr(VI) salts, particularly the insoluble compounds, are well-established human carcinogens, affecting the bronchial cells of the lung. No investigations have studied particulate Cr(VI) and only one has studied soluble Cr(VI) in human bronchial cells. Thus the goal of this research is to understand the mechanisms of Cr(VI)-induced carcinogenesis in human bronchial cells. The general hypothesis guiding this proposal is that particulate Cr(VI) is a more potent carcinogen than soluble Cr(VI) because it can escape cell cycle arrest at genotoxic doses. The specific goal of this project is to establish a human bronchial cell model to investigate these mechanisms. Three hypotheses will be tested: 1) Cr(VI) is genotoxic in human bronchial cells. 2) Particulate Cr(VI) compounds are more potent carcinogens than soluble Cr(VI) compounds because they provide chronic extracellular Cr(VI) exposure and escape cell cycle delay. 3) Particulate Cr(VI) salts escape cell cycle delay because of their divalent counter ion. These hypotheses will be tested with the following: 1) Cr(VI)-induced genotoxicity will be measured by the amount of damage produced in the Comet assay, and in metaphase chromosome spreads. Results will provide the first data on the carcinogenic and genotoxic effects of intact Cr(VI) particles to its target cells. 2) Particle uptake will be measured with transmission electron microscopy and ion uptake will be measured with inductively coupled plasma mass spectrometry. 3). Cell cycle effects will be measured with a mitotic index, fluorescent automated cell sorting and cDNA expression arrays. Results will the first reports of Cr(VI) toxicity in its target cells, the first detailed information of the interaction of Cr(VI) with the cell cycle, and will provide important toxicological data on the differences between particulate and soluble hexavalent chromium. This research is significant because it will provide: 1) an understanding of how Cr(VI) causes genetic in its target cells; 2) essential information to better assess the relative risk of exposure to particulate or soluble Cr(VI); 3) models of human bronchial cells for further study of Cr(VI), other metals, and lung cancer in general.","Toxiology of Particulate Cr(VI)in Human Lung Cells Abs: Cr(VI) salts, particularly the insoluble compounds, are well-established human carcinogens, affecting the bronchial cells of the lung. No investigations have studied particulate Cr(VI) and only one has studied soluble Cr(VI) in human bronchial cells. Thus the goal of this research is to understand the mechanisms of Cr(VI)-induced carcinogenesis in human bronchial cells. The general hypothesis guiding this proposal is that particulate Cr(VI) is a more potent carcinogen than soluble Cr(VI) because it can escape cell cycle arrest at genotoxic doses. The specific goal of this project is to establish a human bronchial cell model to investigate these mechanisms. Three hypotheses will be tested: 1) Cr(VI) is genotoxic in human bronchial cells. 2) Particulate Cr(VI) compounds are more potent carcinogens than soluble Cr(VI) compounds because they provide chronic extracellular Cr(VI) exposure and escape cell cycle delay. 3) Particulate Cr(VI) salts escape cell cycle delay because of their divalent counter ion. These hypotheses will be tested with the following: 1) Cr(VI)-induced genotoxicity will be measured by the amount of damage produced in the Comet assay, and in metaphase chromosome spreads. Results will provide the first data on the carcinogenic and genotoxic effects of intact Cr(VI) particles to its target cells. 2) Particle uptake will be measured with transmission electron microscopy and ion uptake will be measured with inductively coupled plasma mass spectrometry. 3). Cell cycle effects will be measured with a mitotic index, fluorescent automated cell sorting and cDNA expression arrays. Results will the first reports of Cr(VI) toxicity in its target cells, the first detailed information of the interaction of Cr(VI) with the cell cycle, and will provide important toxicological data on the differences between particulate and soluble hexavalent chromium. This research is significant because it will provide: 1) an understanding of how Cr(VI) causes genetic in its target cells; 2) essential information to better assess the relative risk of exposure to particulate or soluble Cr(VI); 3) models of human bronchial cells for further study of Cr(VI), other metals, and lung cancer in general."
1577106,Wise 2003,Toxiology of Particulate Cr(VI)in Human Lung Cells,"Cr(VI) salts, particularly the insoluble compounds, are well-established human carcinogens, affecting the bronchial cells of the lung. No investigations have studied particulate Cr(VI) and only one has studied soluble Cr(VI) in human bronchial cells. Thus the goal of this research is to understand the mechanisms of Cr(VI)-induced carcinogenesis in human bronchial cells. The general hypothesis guiding this proposal is that particulate Cr(VI) is a more potent carcinogen than soluble Cr(VI) because it can escape cell cycle arrest at genotoxic doses. The specific goal of this project is to establish a human bronchial cell model to investigate these mechanisms. Three hypotheses will be tested: 1) Cr(VI) is genotoxic in human bronchial cells. 2) Particulate Cr(VI) compounds are more potent carcinogens than soluble Cr(VI) compounds because they provide chronic extracellular Cr(VI) exposure and escape cell cycle delay. 3) Particulate Cr(VI) salts escape cell cycle delay because of their divalent counter ion. These hypotheses will be tested with the following: 1) Cr(VI)-induced genotoxicity will be measured by the amount of damage produced in the Comet assay, and in metaphase chromosome spreads. Results will provide the first data on the carcinogenic and genotoxic effects of intact Cr(VI) particles to its target cells. 2) Particle uptake will be measured with transmission electron microscopy and ion uptake will be measured with inductively coupled plasma mass spectrometry. 3). Cell cycle effects will be measured with a mitotic index, fluorescent automated cell sorting and cDNA expression arrays. Results will the first reports of Cr(VI) toxicity in its target cells, the first detailed information of the interaction of Cr(VI) with the cell cycle, and will provide important toxicological data on the differences between particulate and soluble hexavalent chromium. This research is significant because it will provide: 1) an understanding of how Cr(VI) causes genetic in its target cells; 2) essential information to better assess the relative risk of exposure to particulate or soluble Cr(VI); 3) models of human bronchial cells for further study of Cr(VI), other metals, and lung cancer in general.","Toxiology of Particulate Cr(VI)in Human Lung Cells Abs: Cr(VI) salts, particularly the insoluble compounds, are well-established human carcinogens, affecting the bronchial cells of the lung. No investigations have studied particulate Cr(VI) and only one has studied soluble Cr(VI) in human bronchial cells. Thus the goal of this research is to understand the mechanisms of Cr(VI)-induced carcinogenesis in human bronchial cells. The general hypothesis guiding this proposal is that particulate Cr(VI) is a more potent carcinogen than soluble Cr(VI) because it can escape cell cycle arrest at genotoxic doses. The specific goal of this project is to establish a human bronchial cell model to investigate these mechanisms. Three hypotheses will be tested: 1) Cr(VI) is genotoxic in human bronchial cells. 2) Particulate Cr(VI) compounds are more potent carcinogens than soluble Cr(VI) compounds because they provide chronic extracellular Cr(VI) exposure and escape cell cycle delay. 3) Particulate Cr(VI) salts escape cell cycle delay because of their divalent counter ion. These hypotheses will be tested with the following: 1) Cr(VI)-induced genotoxicity will be measured by the amount of damage produced in the Comet assay, and in metaphase chromosome spreads. Results will provide the first data on the carcinogenic and genotoxic effects of intact Cr(VI) particles to its target cells. 2) Particle uptake will be measured with transmission electron microscopy and ion uptake will be measured with inductively coupled plasma mass spectrometry. 3). Cell cycle effects will be measured with a mitotic index, fluorescent automated cell sorting and cDNA expression arrays. Results will the first reports of Cr(VI) toxicity in its target cells, the first detailed information of the interaction of Cr(VI) with the cell cycle, and will provide important toxicological data on the differences between particulate and soluble hexavalent chromium. This research is significant because it will provide: 1) an understanding of how Cr(VI) causes genetic in its target cells; 2) essential information to better assess the relative risk of exposure to particulate or soluble Cr(VI); 3) models of human bronchial cells for further study of Cr(VI), other metals, and lung cancer in general."
1577105,Wise 2002,Toxiology of particulate Cr(VI) in hman lung cells,"Cr(VI) salts, particularly the insoluble compounds, are well-established human carcinogens, affecting the bronchial cells of the lung. No investigations have studied particulate Cr(VI) and only one has studied soluble Cr(VI) in human bronchial cells. Thus the goal of this research is to understand the mechanisms of Cr(VI)-induced carcinogenesis in human bronchial cells. The general hypothesis guiding this proposal is that particulate Cr(VI) is a more potent carcinogen than soluble Cr(VI) because it can escape cell cycle arrest at genotoxic doses. The specific goal of this project is to establish a human bronchial cell model to investigate these mechanisms. Three hypotheses will be tested: 1) Cr(VI) is genotoxic in human bronchial cells. 2) Particulate Cr(VI) compounds are more potent carcinogens than soluble Cr(VI) compounds because they provide chronic extracellular Cr(VI) exposure and escape cell cycle delay. 3) Particulate Cr(VI) salts escape cell cycle delay because of their divalent counter ion. These hypotheses will be tested with the following: 1) Cr(VI)-induced genotoxicity will be measured by the amount of damage produced in the Comet assay, and in metaphase chromosome spreads. Results will provide the first data on the carcinogenic and genotoxic effects of intact Cr(VI) particles to its target cells. 2) Particle uptake will be measured with transmission electron microscopy and ion uptake will be measured with inductively coupled plasma mass spectrometry. 3). Cell cycle effects will be measured with a mitotic index, fluorescent automated cell sorting and cDNA expression arrays. Results will the first reports of Cr(VI) toxicity in its target cells, the first detailed information of the interaction of Cr(VI) with the cell cycle, and will provide important toxicological data on the differences between particulate and soluble hexavalent chromium. This research is significant because it will provide: 1) an understanding of how Cr(VI) causes genetic in its target cells; 2) essential information to better assess the relative risk of exposure to particulate or soluble Cr(VI); 3) models of human bronchial cells for further study of Cr(VI), other metals, and lung cancer in general.","Toxiology of particulate Cr(VI) in hman lung cells Abs: Cr(VI) salts, particularly the insoluble compounds, are well-established human carcinogens, affecting the bronchial cells of the lung. No investigations have studied particulate Cr(VI) and only one has studied soluble Cr(VI) in human bronchial cells. Thus the goal of this research is to understand the mechanisms of Cr(VI)-induced carcinogenesis in human bronchial cells. The general hypothesis guiding this proposal is that particulate Cr(VI) is a more potent carcinogen than soluble Cr(VI) because it can escape cell cycle arrest at genotoxic doses. The specific goal of this project is to establish a human bronchial cell model to investigate these mechanisms. Three hypotheses will be tested: 1) Cr(VI) is genotoxic in human bronchial cells. 2) Particulate Cr(VI) compounds are more potent carcinogens than soluble Cr(VI) compounds because they provide chronic extracellular Cr(VI) exposure and escape cell cycle delay. 3) Particulate Cr(VI) salts escape cell cycle delay because of their divalent counter ion. These hypotheses will be tested with the following: 1) Cr(VI)-induced genotoxicity will be measured by the amount of damage produced in the Comet assay, and in metaphase chromosome spreads. Results will provide the first data on the carcinogenic and genotoxic effects of intact Cr(VI) particles to its target cells. 2) Particle uptake will be measured with transmission electron microscopy and ion uptake will be measured with inductively coupled plasma mass spectrometry. 3). Cell cycle effects will be measured with a mitotic index, fluorescent automated cell sorting and cDNA expression arrays. Results will the first reports of Cr(VI) toxicity in its target cells, the first detailed information of the interaction of Cr(VI) with the cell cycle, and will provide important toxicological data on the differences between particulate and soluble hexavalent chromium. This research is significant because it will provide: 1) an understanding of how Cr(VI) causes genetic in its target cells; 2) essential information to better assess the relative risk of exposure to particulate or soluble Cr(VI); 3) models of human bronchial cells for further study of Cr(VI), other metals, and lung cancer in general."
1577104,Wise 2001,Toxiology of Particulate Cr(VI)in Human Lung Cells,"Cr(VI) salts, particularly the insoluble compounds, are well-established human carcinogens, affecting the bronchial cells of the lung. No investigations have studied particulate Cr(VI) and only one has studied soluble Cr(VI) in human bronchial cells. Thus the goal of this research is to understand the mechanisms of Cr(VI)-induced carcinogenesis in human bronchial cells. The general hypothesis guiding this proposal is that particulate Cr(VI) is a more potent carcinogen than soluble Cr(VI) because it can escape cell cycle arrest at genotoxic doses. The specific goal of this project is to establish a human bronchial cell model to investigate these mechanisms. Three hypotheses will be tested: 1) Cr(VI) is genotoxic in human bronchial cells. 2) Particulate Cr(VI) compounds are more potent carcinogens than soluble Cr(VI) compounds because they provide chronic extracellular Cr(VI) exposure and escape cell cycle delay. 3) Particulate Cr(VI) salts escape cell cycle delay because of their divalent counter ion. These hypotheses will be tested with the following: 1) Cr(VI)-induced genotoxicity will be measured by the amount of damage produced in the Comet assay, and in metaphase chromosome spreads. Results will provide the first data on the carcinogenic and genotoxic effects of intact Cr(VI) particles to its target cells. 2) Particle uptake will be measured with transmission electron microscopy and ion uptake will be measured with inductively coupled plasma mass spectrometry. 3). Cell cycle effects will be measured with a mitotic index, fluorescent automated cell sorting and cDNA expression arrays. Results will the first reports of Cr(VI) toxicity in its target cells, the first detailed information of the interaction of Cr(VI) with the cell cycle, and will provide important toxicological data on the differences between particulate and soluble hexavalent chromium. This research is significant because it will provide: 1) an understanding of how Cr(VI) causes genetic in its target cells; 2) essential information to better assess the relative risk of exposure to particulate or soluble Cr(VI); 3) models of human bronchial cells for further study of Cr(VI), other metals, and lung cancer in general.","Toxiology of Particulate Cr(VI)in Human Lung Cells Abs: Cr(VI) salts, particularly the insoluble compounds, are well-established human carcinogens, affecting the bronchial cells of the lung. No investigations have studied particulate Cr(VI) and only one has studied soluble Cr(VI) in human bronchial cells. Thus the goal of this research is to understand the mechanisms of Cr(VI)-induced carcinogenesis in human bronchial cells. The general hypothesis guiding this proposal is that particulate Cr(VI) is a more potent carcinogen than soluble Cr(VI) because it can escape cell cycle arrest at genotoxic doses. The specific goal of this project is to establish a human bronchial cell model to investigate these mechanisms. Three hypotheses will be tested: 1) Cr(VI) is genotoxic in human bronchial cells. 2) Particulate Cr(VI) compounds are more potent carcinogens than soluble Cr(VI) compounds because they provide chronic extracellular Cr(VI) exposure and escape cell cycle delay. 3) Particulate Cr(VI) salts escape cell cycle delay because of their divalent counter ion. These hypotheses will be tested with the following: 1) Cr(VI)-induced genotoxicity will be measured by the amount of damage produced in the Comet assay, and in metaphase chromosome spreads. Results will provide the first data on the carcinogenic and genotoxic effects of intact Cr(VI) particles to its target cells. 2) Particle uptake will be measured with transmission electron microscopy and ion uptake will be measured with inductively coupled plasma mass spectrometry. 3). Cell cycle effects will be measured with a mitotic index, fluorescent automated cell sorting and cDNA expression arrays. Results will the first reports of Cr(VI) toxicity in its target cells, the first detailed information of the interaction of Cr(VI) with the cell cycle, and will provide important toxicological data on the differences between particulate and soluble hexavalent chromium. This research is significant because it will provide: 1) an understanding of how Cr(VI) causes genetic in its target cells; 2) essential information to better assess the relative risk of exposure to particulate or soluble Cr(VI); 3) models of human bronchial cells for further study of Cr(VI), other metals, and lung cancer in general."
1577103,Singh 1998,CHROMIUM INDUCED APOPTOSIS AND GENOTOXICITY,"Certain particulate hexavalent compounds cause lung cancer and respiratory lesions in an occupational setting. Hexavalent chromium enters the cells and is metabolically reduced to trivalent chromium. This process generates transient intermediate oxidation states of chromium and, possibly, reactive oxygen species (ROS). The resulting genetic and cellular damage inhibits cellular DNA replication and transcription, blocks the cell cycle, and causes apoptosis. The overall goals of this proposal are: (1) To investigate the cellular effects of soluble and particulate chromates in two normal human lung cell types that are likely to be targeted by chromium, the normal human lung fibroblasts and the small airway epithelial cells. The role of ROS and DNA-DNA interstrand crosslinks (DDC) in chromium-induced apoptosis, will be studied at the cellular level by using pharmacological antioxidants and Fanconi anemia cells that are deficient in the repair of DDC, respectively. (2) To investigate how DNA-bound chromium affects genomic replication. This will be modeled in vitro by replicating Cr-treated DNA by the human DNA replication complex, the synthesome. Thus, the proposed study will elucidate some of the cellular and molecular mechanisms of chromium-induced genotoxicity and apoptosis in the relevant, target human lung cells. From a public health perspective, this information will be important since it will contribute to our knowledge of the mechanisms of chromium toxicity and carcinogenesis in exposed humans.","CHROMIUM INDUCED APOPTOSIS AND GENOTOXICITY Abs: Certain particulate hexavalent compounds cause lung cancer and respiratory lesions in an occupational setting. Hexavalent chromium enters the cells and is metabolically reduced to trivalent chromium. This process generates transient intermediate oxidation states of chromium and, possibly, reactive oxygen species (ROS). The resulting genetic and cellular damage inhibits cellular DNA replication and transcription, blocks the cell cycle, and causes apoptosis. The overall goals of this proposal are: (1) To investigate the cellular effects of soluble and particulate chromates in two normal human lung cell types that are likely to be targeted by chromium, the normal human lung fibroblasts and the small airway epithelial cells. The role of ROS and DNA-DNA interstrand crosslinks (DDC) in chromium-induced apoptosis, will be studied at the cellular level by using pharmacological antioxidants and Fanconi anemia cells that are deficient in the repair of DDC, respectively. (2) To investigate how DNA-bound chromium affects genomic replication. This will be modeled in vitro by replicating Cr-treated DNA by the human DNA replication complex, the synthesome. Thus, the proposed study will elucidate some of the cellular and molecular mechanisms of chromium-induced genotoxicity and apoptosis in the relevant, target human lung cells. From a public health perspective, this information will be important since it will contribute to our knowledge of the mechanisms of chromium toxicity and carcinogenesis in exposed humans."
1577102,Patierno 2003,PARTICULATE CHROMIUM TOXICITY AND CARCINOGENESIS,"DESCRIPTION (Adapted from the applicant's abstract): The primary object of the proposed research is to investigate the interaction of particulate and soluble hexavalent chromium compounds with normal human small airway epithelial cells (HSAE) and fibroblasts (HLF), which are representative target cells for chromium toxicity and carcinogenesis. Some of these compounds are human respiratory tract toxins and carcinogens which directly damage DNA and alter DNA replication and transcription, may damage subcellular organelles, such as mitochondria, and cause mutations an neoplastic transformation at doses which also induce growth arrest and apoptotic cell death. Using cultured human and rat cells the investigator will test the hypotheses that: (increasing the fraction of cells escaping chromium-induced apoptotic cell death by pharmacologically interfering with apoptotic signaling, results in increased genomic instability and propensity towards mutation and neoplastic transformation, and (ii) chromium-induced apoptosis and/or terminal growth arrest results in part from direct damage to mitochondria, loss of mitochondrial integrity and release of cytochrome c. Implicit in this approach is an examination of the mechanisms of chromium-induced apoptosis and elucidation of signaling pathways which, if altered, might give rise to cells which are predisposed to accelerated multistage carcinogenesis. This research will help to elucidate molecular mechanisms of chromium toxicity and carcinogenesis and will have practival value in contributing to the evaluation of risk to humans exposed to chromates.","PARTICULATE CHROMIUM TOXICITY AND CARCINOGENESIS Abs: DESCRIPTION (Adapted from the applicant's abstract): The primary object of the proposed research is to investigate the interaction of particulate and soluble hexavalent chromium compounds with normal human small airway epithelial cells (HSAE) and fibroblasts (HLF), which are representative target cells for chromium toxicity and carcinogenesis. Some of these compounds are human respiratory tract toxins and carcinogens which directly damage DNA and alter DNA replication and transcription, may damage subcellular organelles, such as mitochondria, and cause mutations an neoplastic transformation at doses which also induce growth arrest and apoptotic cell death. Using cultured human and rat cells the investigator will test the hypotheses that: (increasing the fraction of cells escaping chromium-induced apoptotic cell death by pharmacologically interfering with apoptotic signaling, results in increased genomic instability and propensity towards mutation and neoplastic transformation, and (ii) chromium-induced apoptosis and/or terminal growth arrest results in part from direct damage to mitochondria, loss of mitochondrial integrity and release of cytochrome c. Implicit in this approach is an examination of the mechanisms of chromium-induced apoptosis and elucidation of signaling pathways which, if altered, might give rise to cells which are predisposed to accelerated multistage carcinogenesis. This research will help to elucidate molecular mechanisms of chromium toxicity and carcinogenesis and will have practival value in contributing to the evaluation of risk to humans exposed to chromates."
1577101,Patierno 2002,PARTICULATE CHROMIUM TOXICITY AND CARCINOGENESIS,"DESCRIPTION (Adapted from the applicant's abstract): The primary object of the proposed research is to investigate the interaction of particulate and soluble hexavalent chromium compounds with normal human small airway epithelial cells (HSAE) and fibroblasts (HLF), which are representative target cells for chromium toxicity and carcinogenesis. Some of these compounds are human respiratory tract toxins and carcinogens which directly damage DNA and alter DNA replication and transcription, may damage subcellular organelles, such as mitochondria, and cause mutations an neoplastic transformation at doses which also induce growth arrest and apoptotic cell death. Using cultured human and rat cells the investigator will test the hypotheses that: (increasing the fraction of cells escaping chromium-induced apoptotic cell death by pharmacologically interfering with apoptotic signaling, results in increased genomic instability and propensity towards mutation and neoplastic transformation, and (ii) chromium-induced apoptosis and/or terminal growth arrest results in part from direct damage to mitochondria, loss of mitochondrial integrity and release of cytochrome c. Implicit in this approach is an examination of the mechanisms of chromium-induced apoptosis and elucidation of signaling pathways which, if altered, might give rise to cells which are predisposed to accelerated multistage carcinogenesis. This research will help to elucidate molecular mechanisms of chromium toxicity and carcinogenesis and will have practival value in contributing to the evaluation of risk to humans exposed to chromates.","PARTICULATE CHROMIUM TOXICITY AND CARCINOGENESIS Abs: DESCRIPTION (Adapted from the applicant's abstract): The primary object of the proposed research is to investigate the interaction of particulate and soluble hexavalent chromium compounds with normal human small airway epithelial cells (HSAE) and fibroblasts (HLF), which are representative target cells for chromium toxicity and carcinogenesis. Some of these compounds are human respiratory tract toxins and carcinogens which directly damage DNA and alter DNA replication and transcription, may damage subcellular organelles, such as mitochondria, and cause mutations an neoplastic transformation at doses which also induce growth arrest and apoptotic cell death. Using cultured human and rat cells the investigator will test the hypotheses that: (increasing the fraction of cells escaping chromium-induced apoptotic cell death by pharmacologically interfering with apoptotic signaling, results in increased genomic instability and propensity towards mutation and neoplastic transformation, and (ii) chromium-induced apoptosis and/or terminal growth arrest results in part from direct damage to mitochondria, loss of mitochondrial integrity and release of cytochrome c. Implicit in this approach is an examination of the mechanisms of chromium-induced apoptosis and elucidation of signaling pathways which, if altered, might give rise to cells which are predisposed to accelerated multistage carcinogenesis. This research will help to elucidate molecular mechanisms of chromium toxicity and carcinogenesis and will have practival value in contributing to the evaluation of risk to humans exposed to chromates."
1577100,Patierno 2001,PARTICULATE CHROMIUM TOXICITY AND CARCINOGENESIS,"DESCRIPTION (Adapted from the applicant's abstract): The primary object of the proposed research is to investigate the interaction of particulate and soluble hexavalent chromium compounds with normal human small airway epithelial cells (HSAE) and fibroblasts (HLF), which are representative target cells for chromium toxicity and carcinogenesis. Some of these compounds are human respiratory tract toxins and carcinogens which directly damage DNA and alter DNA replication and transcription, may damage subcellular organelles, such as mitochondria, and cause mutations an neoplastic transformation at doses which also induce growth arrest and apoptotic cell death. Using cultured human and rat cells the investigator will test the hypotheses that: (increasing the fraction of cells escaping chromium-induced apoptotic cell death by pharmacologically interfering with apoptotic signaling, results in increased genomic instability and propensity towards mutation and neoplastic transformation, and (ii) chromium-induced apoptosis and/or terminal growth arrest results in part from direct damage to mitochondria, loss of mitochondrial integrity and release of cytochrome c. Implicit in this approach is an examination of the mechanisms of chromium-induced apoptosis and elucidation of signaling pathways which, if altered, might give rise to cells which are predisposed to accelerated multistage carcinogenesis. This research will help to elucidate molecular mechanisms of chromium toxicity and carcinogenesis and will have practival value in contributing to the evaluation of risk to humans exposed to chromates.","PARTICULATE CHROMIUM TOXICITY AND CARCINOGENESIS Abs: DESCRIPTION (Adapted from the applicant's abstract): The primary object of the proposed research is to investigate the interaction of particulate and soluble hexavalent chromium compounds with normal human small airway epithelial cells (HSAE) and fibroblasts (HLF), which are representative target cells for chromium toxicity and carcinogenesis. Some of these compounds are human respiratory tract toxins and carcinogens which directly damage DNA and alter DNA replication and transcription, may damage subcellular organelles, such as mitochondria, and cause mutations an neoplastic transformation at doses which also induce growth arrest and apoptotic cell death. Using cultured human and rat cells the investigator will test the hypotheses that: (increasing the fraction of cells escaping chromium-induced apoptotic cell death by pharmacologically interfering with apoptotic signaling, results in increased genomic instability and propensity towards mutation and neoplastic transformation, and (ii) chromium-induced apoptosis and/or terminal growth arrest results in part from direct damage to mitochondria, loss of mitochondrial integrity and release of cytochrome c. Implicit in this approach is an examination of the mechanisms of chromium-induced apoptosis and elucidation of signaling pathways which, if altered, might give rise to cells which are predisposed to accelerated multistage carcinogenesis. This research will help to elucidate molecular mechanisms of chromium toxicity and carcinogenesis and will have practival value in contributing to the evaluation of risk to humans exposed to chromates."
1577099,Patierno 2000,PARTICULATE CHROMIUM TOXICITY AND CARCINOGENESIS,"DESCRIPTION (Adapted from the applicant's abstract): The primary object of the proposed research is to investigate the interaction of particulate and soluble hexavalent chromium compounds with normal human small airway epithelial cells (HSAE) and fibroblasts (HLF), which are representative target cells for chromium toxicity and carcinogenesis. Some of these compounds are human respiratory tract toxins and carcinogens which directly damage DNA and alter DNA replication and transcription, may damage subcellular organelles, such as mitochondria, and cause mutations an neoplastic transformation at doses which also induce growth arrest and apoptotic cell death. Using cultured human and rat cells the investigator will test the hypotheses that: (increasing the fraction of cells escaping chromium-induced apoptotic cell death by pharmacologically interfering with apoptotic signaling, results in increased genomic instability and propensity towards mutation and neoplastic transformation, and (ii) chromium-induced apoptosis and/or terminal growth arrest results in part from direct damage to mitochondria, loss of mitochondrial integrity and release of cytochrome c. Implicit in this approach is an examination of the mechanisms of chromium-induced apoptosis and elucidation of signaling pathways which, if altered, might give rise to cells which are predisposed to accelerated multistage carcinogenesis. This research will help to elucidate molecular mechanisms of chromium toxicity and carcinogenesis and will have practival value in contributing to the evaluation of risk to humans exposed to chromates.","PARTICULATE CHROMIUM TOXICITY AND CARCINOGENESIS Abs: DESCRIPTION (Adapted from the applicant's abstract): The primary object of the proposed research is to investigate the interaction of particulate and soluble hexavalent chromium compounds with normal human small airway epithelial cells (HSAE) and fibroblasts (HLF), which are representative target cells for chromium toxicity and carcinogenesis. Some of these compounds are human respiratory tract toxins and carcinogens which directly damage DNA and alter DNA replication and transcription, may damage subcellular organelles, such as mitochondria, and cause mutations an neoplastic transformation at doses which also induce growth arrest and apoptotic cell death. Using cultured human and rat cells the investigator will test the hypotheses that: (increasing the fraction of cells escaping chromium-induced apoptotic cell death by pharmacologically interfering with apoptotic signaling, results in increased genomic instability and propensity towards mutation and neoplastic transformation, and (ii) chromium-induced apoptosis and/or terminal growth arrest results in part from direct damage to mitochondria, loss of mitochondrial integrity and release of cytochrome c. Implicit in this approach is an examination of the mechanisms of chromium-induced apoptosis and elucidation of signaling pathways which, if altered, might give rise to cells which are predisposed to accelerated multistage carcinogenesis. This research will help to elucidate molecular mechanisms of chromium toxicity and carcinogenesis and will have practival value in contributing to the evaluation of risk to humans exposed to chromates."
1577098,Costa 2005,Detection of Cr- DNA adducts in human,"Hexavalent chromium is a well established human carcinogen and is a contaminant at numerous Superfund toxic waste dump sites. Carcinogenesis by hexavalent chromium is thought to involve the formation of Cr-DNA adducts. About 50% of the chromium is bound to DNA as ternary complexes of Cr (III) with either amino acids or glutathione. Additionally, hexavalent chromium has been shown to interact with DNA in a non-random fashion targeting itself to promoters and coding regions of highly inducible genes. Previous studies in humans have suggested that there is a large intra-individual variability in the uptake of chromate. Using he bacterial repair enzymes UvrABC and the technique of ligation-mediated PCR, we will study whether the UvrABC bacterial enzymes can detect and differentiate Cr-DNA complexes including Cr(III)-DNA binary, as well as (Cr(III)-DNA ternary complexes involving either cysteine, histidine, or glutathione within exon 7 of the p53 gene. We will also investigate the effect of cytosine methylation on the formation of adducts in human lymphocytes following exposure to hexavalent chromium within other DNA regions that we can analyze for hotspots of Cr-DNA adducts. Bacterial repair enzymes will cut at Cr adducts, and Southern blotting will measure the hybridization signal in the cut region compared to the uncut DNA using probes, such as the ornithine decarboxylase (ODC) promoter and the p53 coding regions. We will examine hexavalent chromium uptake in 60 human volunteers and identify those with the highest uptake capacity and highest intracellular levels of chromium and high chromate uptake will be utilized to map the Cr-DNA adducts at a single nucleotide level in p53 exon 5 and 7, as well as other DNA regions. These studies attempt to develop biomarkers of exposure and effect of carcinogenic hexavalent chromium. We consider important parameters of genetic diversity including epigenetic differences in DNA methylation and the interindividual diversity of chromatic uptake into cells. These studies should lead to new methodologies for assessing the impact of environmental exposure of hexavalent chromium to the human population and identify factors of susceptibility that enhance Cr toxicity.","Detection of Cr- DNA adducts in human Abs: Hexavalent chromium is a well established human carcinogen and is a contaminant at numerous Superfund toxic waste dump sites. Carcinogenesis by hexavalent chromium is thought to involve the formation of Cr-DNA adducts. About 50% of the chromium is bound to DNA as ternary complexes of Cr (III) with either amino acids or glutathione. Additionally, hexavalent chromium has been shown to interact with DNA in a non-random fashion targeting itself to promoters and coding regions of highly inducible genes. Previous studies in humans have suggested that there is a large intra-individual variability in the uptake of chromate. Using he bacterial repair enzymes UvrABC and the technique of ligation-mediated PCR, we will study whether the UvrABC bacterial enzymes can detect and differentiate Cr-DNA complexes including Cr(III)-DNA binary, as well as (Cr(III)-DNA ternary complexes involving either cysteine, histidine, or glutathione within exon 7 of the p53 gene. We will also investigate the effect of cytosine methylation on the formation of adducts in human lymphocytes following exposure to hexavalent chromium within other DNA regions that we can analyze for hotspots of Cr-DNA adducts. Bacterial repair enzymes will cut at Cr adducts, and Southern blotting will measure the hybridization signal in the cut region compared to the uncut DNA using probes, such as the ornithine decarboxylase (ODC) promoter and the p53 coding regions. We will examine hexavalent chromium uptake in 60 human volunteers and identify those with the highest uptake capacity and highest intracellular levels of chromium and high chromate uptake will be utilized to map the Cr-DNA adducts at a single nucleotide level in p53 exon 5 and 7, as well as other DNA regions. These studies attempt to develop biomarkers of exposure and effect of carcinogenic hexavalent chromium. We consider important parameters of genetic diversity including epigenetic differences in DNA methylation and the interindividual diversity of chromatic uptake into cells. These studies should lead to new methodologies for assessing the impact of environmental exposure of hexavalent chromium to the human population and identify factors of susceptibility that enhance Cr toxicity."
1577097,Costa 2003,Detection of Cr- DNA adducts in human,"Hexavalent chromium is a well established human carcinogen and is a contaminant at numerous Superfund toxic waste dump sites. Carcinogenesis by hexavalent chromium is thought to involve the formation of Cr-DNA adducts. About 50% of the chromium is bound to DNA as ternary complexes of Cr (III) with either amino acids or glutathione. Additionally, hexavalent chromium has been shown to interact with DNA in a non-random fashion targeting itself to promoters and coding regions of highly inducible genes. Previous studies in humans have suggested that there is a large intra-individual variability in the uptake of chromate. Using he bacterial repair enzymes UvrABC and the technique of ligation-mediated PCR, we will study whether the UvrABC bacterial enzymes can detect and differentiate Cr-DNA complexes including Cr(III)-DNA binary, as well as (Cr(III)-DNA ternary complexes involving either cysteine, histidine, or glutathione within exon 7 of the p53 gene. We will also investigate the effect of cytosine methylation on the formation of adducts in human lymphocytes following exposure to hexavalent chromium within other DNA regions that we can analyze for hotspots of Cr-DNA adducts. Bacterial repair enzymes will cut at Cr adducts, and Southern blotting will measure the hybridization signal in the cut region compared to the uncut DNA using probes, such as the ornithine decarboxylase (ODC) promoter and the p53 coding regions. We will examine hexavalent chromium uptake in 60 human volunteers and identify those with the highest uptake capacity and highest intracellular levels of chromium and high chromate uptake will be utilized to map the Cr-DNA adducts at a single nucleotide level in p53 exon 5 and 7, as well as other DNA regions. These studies attempt to develop biomarkers of exposure and effect of carcinogenic hexavalent chromium. We consider important parameters of genetic diversity including epigenetic differences in DNA methylation and the interindividual diversity of chromatic uptake into cells. These studies should lead to new methodologies for assessing the impact of environmental exposure of hexavalent chromium to the human population and identify factors of susceptibility that enhance Cr toxicity.","Detection of Cr- DNA adducts in human Abs: Hexavalent chromium is a well established human carcinogen and is a contaminant at numerous Superfund toxic waste dump sites. Carcinogenesis by hexavalent chromium is thought to involve the formation of Cr-DNA adducts. About 50% of the chromium is bound to DNA as ternary complexes of Cr (III) with either amino acids or glutathione. Additionally, hexavalent chromium has been shown to interact with DNA in a non-random fashion targeting itself to promoters and coding regions of highly inducible genes. Previous studies in humans have suggested that there is a large intra-individual variability in the uptake of chromate. Using he bacterial repair enzymes UvrABC and the technique of ligation-mediated PCR, we will study whether the UvrABC bacterial enzymes can detect and differentiate Cr-DNA complexes including Cr(III)-DNA binary, as well as (Cr(III)-DNA ternary complexes involving either cysteine, histidine, or glutathione within exon 7 of the p53 gene. We will also investigate the effect of cytosine methylation on the formation of adducts in human lymphocytes following exposure to hexavalent chromium within other DNA regions that we can analyze for hotspots of Cr-DNA adducts. Bacterial repair enzymes will cut at Cr adducts, and Southern blotting will measure the hybridization signal in the cut region compared to the uncut DNA using probes, such as the ornithine decarboxylase (ODC) promoter and the p53 coding regions. We will examine hexavalent chromium uptake in 60 human volunteers and identify those with the highest uptake capacity and highest intracellular levels of chromium and high chromate uptake will be utilized to map the Cr-DNA adducts at a single nucleotide level in p53 exon 5 and 7, as well as other DNA regions. These studies attempt to develop biomarkers of exposure and effect of carcinogenic hexavalent chromium. We consider important parameters of genetic diversity including epigenetic differences in DNA methylation and the interindividual diversity of chromatic uptake into cells. These studies should lead to new methodologies for assessing the impact of environmental exposure of hexavalent chromium to the human population and identify factors of susceptibility that enhance Cr toxicity."
1577096,Costa 2002,Detection of Cr- DNA adducts in human,"Hexavalent chromium is a well established human carcinogen and is a contaminant at numerous Superfund toxic waste dump sites. Carcinogenesis by hexavalent chromium is thought to involve the formation of Cr-DNA adducts. About 50% of the chromium is bound to DNA as ternary complexes of Cr (III) with either amino acids or glutathione. Additionally, hexavalent chromium has been shown to interact with DNA in a non-random fashion targeting itself to promoters and coding regions of highly inducible genes. Previous studies in humans have suggested that there is a large intra-individual variability in the uptake of chromate. Using he bacterial repair enzymes UvrABC and the technique of ligation-mediated PCR, we will study whether the UvrABC bacterial enzymes can detect and differentiate Cr-DNA complexes including Cr(III)-DNA binary, as well as (Cr(III)-DNA ternary complexes involving either cysteine, histidine, or glutathione within exon 7 of the p53 gene. We will also investigate the effect of cytosine methylation on the formation of adducts in human lymphocytes following exposure to hexavalent chromium within other DNA regions that we can analyze for hotspots of Cr-DNA adducts. Bacterial repair enzymes will cut at Cr adducts, and Southern blotting will measure the hybridization signal in the cut region compared to the uncut DNA using probes, such as the ornithine decarboxylase (ODC) promoter and the p53 coding regions. We will examine hexavalent chromium uptake in 60 human volunteers and identify those with the highest uptake capacity and highest intracellular levels of chromium and high chromate uptake will be utilized to map the Cr-DNA adducts at a single nucleotide level in p53 exon 5 and 7, as well as other DNA regions. These studies attempt to develop biomarkers of exposure and effect of carcinogenic hexavalent chromium. We consider important parameters of genetic diversity including epigenetic differences in DNA methylation and the interindividual diversity of chromatic uptake into cells. These studies should lead to new methodologies for assessing the impact of environmental exposure of hexavalent chromium to the human population and identify factors of susceptibility that enhance Cr toxicity.","Detection of Cr- DNA adducts in human Abs: Hexavalent chromium is a well established human carcinogen and is a contaminant at numerous Superfund toxic waste dump sites. Carcinogenesis by hexavalent chromium is thought to involve the formation of Cr-DNA adducts. About 50% of the chromium is bound to DNA as ternary complexes of Cr (III) with either amino acids or glutathione. Additionally, hexavalent chromium has been shown to interact with DNA in a non-random fashion targeting itself to promoters and coding regions of highly inducible genes. Previous studies in humans have suggested that there is a large intra-individual variability in the uptake of chromate. Using he bacterial repair enzymes UvrABC and the technique of ligation-mediated PCR, we will study whether the UvrABC bacterial enzymes can detect and differentiate Cr-DNA complexes including Cr(III)-DNA binary, as well as (Cr(III)-DNA ternary complexes involving either cysteine, histidine, or glutathione within exon 7 of the p53 gene. We will also investigate the effect of cytosine methylation on the formation of adducts in human lymphocytes following exposure to hexavalent chromium within other DNA regions that we can analyze for hotspots of Cr-DNA adducts. Bacterial repair enzymes will cut at Cr adducts, and Southern blotting will measure the hybridization signal in the cut region compared to the uncut DNA using probes, such as the ornithine decarboxylase (ODC) promoter and the p53 coding regions. We will examine hexavalent chromium uptake in 60 human volunteers and identify those with the highest uptake capacity and highest intracellular levels of chromium and high chromate uptake will be utilized to map the Cr-DNA adducts at a single nucleotide level in p53 exon 5 and 7, as well as other DNA regions. These studies attempt to develop biomarkers of exposure and effect of carcinogenic hexavalent chromium. We consider important parameters of genetic diversity including epigenetic differences in DNA methylation and the interindividual diversity of chromatic uptake into cells. These studies should lead to new methodologies for assessing the impact of environmental exposure of hexavalent chromium to the human population and identify factors of susceptibility that enhance Cr toxicity."
1577095,Costa 2001,Detection of Cr- DNA adducts in human,"Hexavalent chromium is a well established human carcinogen and is a contaminant at numerous Superfund toxic waste dump sites. Carcinogenesis by hexavalent chromium is thought to involve the formation of Cr-DNA adducts. About 50% of the chromium is bound to DNA as ternary complexes of Cr (III) with either amino acids or glutathione. Additionally, hexavalent chromium has been shown to interact with DNA in a non-random fashion targeting itself to promoters and coding regions of highly inducible genes. Previous studies in humans have suggested that there is a large intra-individual variability in the uptake of chromate. Using he bacterial repair enzymes UvrABC and the technique of ligation-mediated PCR, we will study whether the UvrABC bacterial enzymes can detect and differentiate Cr-DNA complexes including Cr(III)-DNA binary, as well as (Cr(III)-DNA ternary complexes involving either cysteine, histidine, or glutathione within exon 7 of the p53 gene. We will also investigate the effect of cytosine methylation on the formation of adducts in human lymphocytes following exposure to hexavalent chromium within other DNA regions that we can analyze for hotspots of Cr-DNA adducts. Bacterial repair enzymes will cut at Cr adducts, and Southern blotting will measure the hybridization signal in the cut region compared to the uncut DNA using probes, such as the ornithine decarboxylase (ODC) promoter and the p53 coding regions. We will examine hexavalent chromium uptake in 60 human volunteers and identify those with the highest uptake capacity and highest intracellular levels of chromium and high chromate uptake will be utilized to map the Cr-DNA adducts at a single nucleotide level in p53 exon 5 and 7, as well as other DNA regions. These studies attempt to develop biomarkers of exposure and effect of carcinogenic hexavalent chromium. We consider important parameters of genetic diversity including epigenetic differences in DNA methylation and the interindividual diversity of chromatic uptake into cells. These studies should lead to new methodologies for assessing the impact of environmental exposure of hexavalent chromium to the human population and identify factors of susceptibility that enhance Cr toxicity.","Detection of Cr- DNA adducts in human Abs: Hexavalent chromium is a well established human carcinogen and is a contaminant at numerous Superfund toxic waste dump sites. Carcinogenesis by hexavalent chromium is thought to involve the formation of Cr-DNA adducts. About 50% of the chromium is bound to DNA as ternary complexes of Cr (III) with either amino acids or glutathione. Additionally, hexavalent chromium has been shown to interact with DNA in a non-random fashion targeting itself to promoters and coding regions of highly inducible genes. Previous studies in humans have suggested that there is a large intra-individual variability in the uptake of chromate. Using he bacterial repair enzymes UvrABC and the technique of ligation-mediated PCR, we will study whether the UvrABC bacterial enzymes can detect and differentiate Cr-DNA complexes including Cr(III)-DNA binary, as well as (Cr(III)-DNA ternary complexes involving either cysteine, histidine, or glutathione within exon 7 of the p53 gene. We will also investigate the effect of cytosine methylation on the formation of adducts in human lymphocytes following exposure to hexavalent chromium within other DNA regions that we can analyze for hotspots of Cr-DNA adducts. Bacterial repair enzymes will cut at Cr adducts, and Southern blotting will measure the hybridization signal in the cut region compared to the uncut DNA using probes, such as the ornithine decarboxylase (ODC) promoter and the p53 coding regions. We will examine hexavalent chromium uptake in 60 human volunteers and identify those with the highest uptake capacity and highest intracellular levels of chromium and high chromate uptake will be utilized to map the Cr-DNA adducts at a single nucleotide level in p53 exon 5 and 7, as well as other DNA regions. These studies attempt to develop biomarkers of exposure and effect of carcinogenic hexavalent chromium. We consider important parameters of genetic diversity including epigenetic differences in DNA methylation and the interindividual diversity of chromatic uptake into cells. These studies should lead to new methodologies for assessing the impact of environmental exposure of hexavalent chromium to the human population and identify factors of susceptibility that enhance Cr toxicity."
1577094,Costa 2000,Detection of Cr- DNA adducts in human,"Hexavalent chromium is a well established human carcinogen and is a contaminant at numerous Superfund toxic waste dump sites. Carcinogenesis by hexavalent chromium is thought to involve the formation of Cr-DNA adducts. About 50% of the chromium is bound to DNA as ternary complexes of Cr (III) with either amino acids or glutathione. Additionally, hexavalent chromium has been shown to interact with DNA in a non-random fashion targeting itself to promoters and coding regions of highly inducible genes. Previous studies in humans have suggested that there is a large intra-individual variability in the uptake of chromate. Using he bacterial repair enzymes UvrABC and the technique of ligation-mediated PCR, we will study whether the UvrABC bacterial enzymes can detect and differentiate Cr-DNA complexes including Cr(III)-DNA binary, as well as (Cr(III)-DNA ternary complexes involving either cysteine, histidine, or glutathione within exon 7 of the p53 gene. We will also investigate the effect of cytosine methylation on the formation of adducts in human lymphocytes following exposure to hexavalent chromium within other DNA regions that we can analyze for hotspots of Cr-DNA adducts. Bacterial repair enzymes will cut at Cr adducts, and Southern blotting will measure the hybridization signal in the cut region compared to the uncut DNA using probes, such as the ornithine decarboxylase (ODC) promoter and the p53 coding regions. We will examine hexavalent chromium uptake in 60 human volunteers and identify those with the highest uptake capacity and highest intracellular levels of chromium and high chromate uptake will be utilized to map the Cr-DNA adducts at a single nucleotide level in p53 exon 5 and 7, as well as other DNA regions. These studies attempt to develop biomarkers of exposure and effect of carcinogenic hexavalent chromium. We consider important parameters of genetic diversity including epigenetic differences in DNA methylation and the interindividual diversity of chromatic uptake into cells. These studies should lead to new methodologies for assessing the impact of environmental exposure of hexavalent chromium to the human population and identify factors of susceptibility that enhance Cr toxicity.","Detection of Cr- DNA adducts in human Abs: Hexavalent chromium is a well established human carcinogen and is a contaminant at numerous Superfund toxic waste dump sites. Carcinogenesis by hexavalent chromium is thought to involve the formation of Cr-DNA adducts. About 50% of the chromium is bound to DNA as ternary complexes of Cr (III) with either amino acids or glutathione. Additionally, hexavalent chromium has been shown to interact with DNA in a non-random fashion targeting itself to promoters and coding regions of highly inducible genes. Previous studies in humans have suggested that there is a large intra-individual variability in the uptake of chromate. Using he bacterial repair enzymes UvrABC and the technique of ligation-mediated PCR, we will study whether the UvrABC bacterial enzymes can detect and differentiate Cr-DNA complexes including Cr(III)-DNA binary, as well as (Cr(III)-DNA ternary complexes involving either cysteine, histidine, or glutathione within exon 7 of the p53 gene. We will also investigate the effect of cytosine methylation on the formation of adducts in human lymphocytes following exposure to hexavalent chromium within other DNA regions that we can analyze for hotspots of Cr-DNA adducts. Bacterial repair enzymes will cut at Cr adducts, and Southern blotting will measure the hybridization signal in the cut region compared to the uncut DNA using probes, such as the ornithine decarboxylase (ODC) promoter and the p53 coding regions. We will examine hexavalent chromium uptake in 60 human volunteers and identify those with the highest uptake capacity and highest intracellular levels of chromium and high chromate uptake will be utilized to map the Cr-DNA adducts at a single nucleotide level in p53 exon 5 and 7, as well as other DNA regions. These studies attempt to develop biomarkers of exposure and effect of carcinogenic hexavalent chromium. We consider important parameters of genetic diversity including epigenetic differences in DNA methylation and the interindividual diversity of chromatic uptake into cells. These studies should lead to new methodologies for assessing the impact of environmental exposure of hexavalent chromium to the human population and identify factors of susceptibility that enhance Cr toxicity."
1577093,Ceryak 2005,Survival Signaling After Genotoxic Insult,"DESCRIPTION (provided by applicant): Inappropriate activation/inactivation of key signals that control cell survival after genotoxic insult can contribute to autonomous growth and neoplastic transformation. An initial consequence of genotoxic injury is cell cycle checkpoint arrest but genotoxicity may also activate cell death pathways of apoptosis or terminal growth arrest. Cellular survival responses to genotoxic insult may produce intrinsic death-resistance; such a selective growth advantage may allow for emergence of a transformed phenotype. Certain forms of hexavalent chromium [(Cr(VI)] are known human respiratory carcinogens that can be employed as useful genotoxic tools with relevant toxicological importance. Our preliminary studies suggest that maintenance of protein tyrosine phosphorylation, which is coincident with AKT activation, overrides Cr-induced growth arrest and enhances clonogenic survival. Constitutive AKT activation is known to play an important role in carcinogenesis. Therefore, the overall objective of this proposal is to elucidate the coordinate signaling events that mediate cell fate determination and survival after genotoxic insult. The dual overarching hypotheses of the proposed studies are that: 1) AKT activation shifts the balance of cell fates, toward survival, after Cr(Vl) genotoxic insult; and 2) AKT activation in the face of Cr(Vl) genotoxic insult increases genomic instability. To test these hypotheses, we will employ molecular, pharmacological and genetic approaches, by using relevant model systems of human diploid lung fibroblasts (HLF), and human large airway epithelial cells (HLAE) and studying the involvement of key signaling components of the AKT pathway. The molecular circuitry of the AKT effect will be delineated in Aim 1, and the consequences of an AKT-induced ""override"" of the genotoxin-elicited program of cell death will be investigated in Aim 2. Aim 3 will identify the role of AKT in resistance to Cr(Vl)-induced clonogenic lethality in a subclonal population of cells with acquired resistance to Cr-induced clonogenic death. We will use soluble Na2CrO4 at a range of concentrations relevant to human exposure, and for which the DNA adduct frequencies and genotoxic lesions are well documented. Results of the proposed studies will identify molecular mechanism(s) that confer a growth advantage to cells after genotoxic insult, and add new insights to the understanding of Cr(Vl)-induced lung carcinogenesis, while addressing a need for sensitive and specific molecular indices that can be correlated with exposure to carcinogenic agents, as well as with their cancer incidence. Delineation of the molecular circuitry involved in AKT survival signaling may have the added benefit of identifying molecular targets for rational drug design in anti-cancer therapy.","Survival Signaling After Genotoxic Insult Abs: DESCRIPTION (provided by applicant): Inappropriate activation/inactivation of key signals that control cell survival after genotoxic insult can contribute to autonomous growth and neoplastic transformation. An initial consequence of genotoxic injury is cell cycle checkpoint arrest but genotoxicity may also activate cell death pathways of apoptosis or terminal growth arrest. Cellular survival responses to genotoxic insult may produce intrinsic death-resistance; such a selective growth advantage may allow for emergence of a transformed phenotype. Certain forms of hexavalent chromium [(Cr(VI)] are known human respiratory carcinogens that can be employed as useful genotoxic tools with relevant toxicological importance. Our preliminary studies suggest that maintenance of protein tyrosine phosphorylation, which is coincident with AKT activation, overrides Cr-induced growth arrest and enhances clonogenic survival. Constitutive AKT activation is known to play an important role in carcinogenesis. Therefore, the overall objective of this proposal is to elucidate the coordinate signaling events that mediate cell fate determination and survival after genotoxic insult. The dual overarching hypotheses of the proposed studies are that: 1) AKT activation shifts the balance of cell fates, toward survival, after Cr(Vl) genotoxic insult; and 2) AKT activation in the face of Cr(Vl) genotoxic insult increases genomic instability. To test these hypotheses, we will employ molecular, pharmacological and genetic approaches, by using relevant model systems of human diploid lung fibroblasts (HLF), and human large airway epithelial cells (HLAE) and studying the involvement of key signaling components of the AKT pathway. The molecular circuitry of the AKT effect will be delineated in Aim 1, and the consequences of an AKT-induced ""override"" of the genotoxin-elicited program of cell death will be investigated in Aim 2. Aim 3 will identify the role of AKT in resistance to Cr(Vl)-induced clonogenic lethality in a subclonal population of cells with acquired resistance to Cr-induced clonogenic death. We will use soluble Na2CrO4 at a range of concentrations relevant to human exposure, and for which the DNA adduct frequencies and genotoxic lesions are well documented. Results of the proposed studies will identify molecular mechanism(s) that confer a growth advantage to cells after genotoxic insult, and add new insights to the understanding of Cr(Vl)-induced lung carcinogenesis, while addressing a need for sensitive and specific molecular indices that can be correlated with exposure to carcinogenic agents, as well as with their cancer incidence. Delineation of the molecular circuitry involved in AKT survival signaling may have the added benefit of identifying molecular targets for rational drug design in anti-cancer therapy."
1577092,Barchowsky 2005,REGULATION OF TRANSCRIPTIONAL COMPETENCE BY CHROMIUM,"Hexavalent chromium (Cr(VI)) is in the top 20 compounds of the ATSDR/EPA priority list since it promotes interstitial lung fibrosis, induces asthma, and is recognized as a probable human lung carcinogen. Despite the epidemiological evidence for both occupationally and environmentally-derived pulmonary disease following inhalation of Cr(VI), there are few studies that define the cellular and molecular basis for pathologic changes in the Cr(VI)-exposed lung. Overall Objective: The overall objective of the proposed studies is to define the molecular signaling mechanisms through which non-cytotoxic concentrations of Cr(VI) alter inducible cytokine and profibrotic gene expression in airway and alveolar epithelial cells. We have recently defined a novel pathway through which Cr(VI) inhibits the transcriptional competence of the transcription factor NF-kappaB by promoting recruitment of the essential co-activator CREB-binding protein (CBP) to c-Jun. We hypothesize that Cr(VI)-induced alteration of co-activator recruitment changes the profile of inducible gene expression and potentiates Fas-induced apoptosis. These effects of Cr(VI) favor development of pulmonary fibrosis. Specific Objectives: Aim 1 of the grant will use human lung cells in culture to define cellular signaling pathways that regulate Cr(VI)-induced recruitment of CBP to specific transcription factors (e.g. c-Jun). Aim 2 will use these models to demonstrate that competition for CBP is the rate limiting step in Cr(VI)- induced loss of NF-kappaB transactivation. The consequence of a switch in CBP-dependent transcription factor competence on FAS- induced apoptosis and gene expression will be examined. The final Aim will use normal and unique transgenic mouse models to examine Cr(VI)-induced regulation of transcription factor activity and of inducible pro-apoptotic and pro-fibrotic phenotypic changes in vivo. Significance: The studies will define fundamental epigenetic mechanisms for altered inducible gene expression and increased susceptibility of airway and alveolar epithelial cells to apoptosis following exposure to Cr(VI). Apoptosis of the airway is now recognized as an underlying non-inflammatory mechanism for lung fibrosis. Thus, these studies will translate observations in cell culture into in vivo models of exposure to greatly improve the basic understanding of how Cr(VI) promotes pulmonary diseases.","REGULATION OF TRANSCRIPTIONAL COMPETENCE BY CHROMIUM Abs: Hexavalent chromium (Cr(VI)) is in the top 20 compounds of the ATSDR/EPA priority list since it promotes interstitial lung fibrosis, induces asthma, and is recognized as a probable human lung carcinogen. Despite the epidemiological evidence for both occupationally and environmentally-derived pulmonary disease following inhalation of Cr(VI), there are few studies that define the cellular and molecular basis for pathologic changes in the Cr(VI)-exposed lung. Overall Objective: The overall objective of the proposed studies is to define the molecular signaling mechanisms through which non-cytotoxic concentrations of Cr(VI) alter inducible cytokine and profibrotic gene expression in airway and alveolar epithelial cells. We have recently defined a novel pathway through which Cr(VI) inhibits the transcriptional competence of the transcription factor NF-kappaB by promoting recruitment of the essential co-activator CREB-binding protein (CBP) to c-Jun. We hypothesize that Cr(VI)-induced alteration of co-activator recruitment changes the profile of inducible gene expression and potentiates Fas-induced apoptosis. These effects of Cr(VI) favor development of pulmonary fibrosis. Specific Objectives: Aim 1 of the grant will use human lung cells in culture to define cellular signaling pathways that regulate Cr(VI)-induced recruitment of CBP to specific transcription factors (e.g. c-Jun). Aim 2 will use these models to demonstrate that competition for CBP is the rate limiting step in Cr(VI)- induced loss of NF-kappaB transactivation. The consequence of a switch in CBP-dependent transcription factor competence on FAS- induced apoptosis and gene expression will be examined. The final Aim will use normal and unique transgenic mouse models to examine Cr(VI)-induced regulation of transcription factor activity and of inducible pro-apoptotic and pro-fibrotic phenotypic changes in vivo. Significance: The studies will define fundamental epigenetic mechanisms for altered inducible gene expression and increased susceptibility of airway and alveolar epithelial cells to apoptosis following exposure to Cr(VI). Apoptosis of the airway is now recognized as an underlying non-inflammatory mechanism for lung fibrosis. Thus, these studies will translate observations in cell culture into in vivo models of exposure to greatly improve the basic understanding of how Cr(VI) promotes pulmonary diseases."
1577091,Barchowsky 2004,REGULATION OF TRANSCRIPTIONAL COMPETENCE BY CHROMIUM,"Hexavalent chromium (Cr(VI)) is in the top 20 compounds of the ATSDR/EPA priority list since it promotes interstitial lung fibrosis, induces asthma, and is recognized as a probable human lung carcinogen. Despite the epidemiological evidence for both occupationally and environmentally-derived pulmonary disease following inhalation of Cr(VI), there are few studies that define the cellular and molecular basis for pathologic changes in the Cr(VI)-exposed lung. Overall Objective: The overall objective of the proposed studies is to define the molecular signaling mechanisms through which non-cytotoxic concentrations of Cr(VI) alter inducible cytokine and profibrotic gene expression in airway and alveolar epithelial cells. We have recently defined a novel pathway through which Cr(VI) inhibits the transcriptional competence of the transcription factor NF-kappaB by promoting recruitment of the essential co-activator CREB-binding protein (CBP) to c-Jun. We hypothesize that Cr(VI)-induced alteration of co-activator recruitment changes the profile of inducible gene expression and potentiates Fas-induced apoptosis. These effects of Cr(VI) favor development of pulmonary fibrosis. Specific Objectives: Aim 1 of the grant will use human lung cells in culture to define cellular signaling pathways that regulate Cr(VI)-induced recruitment of CBP to specific transcription factors (e.g. c-Jun). Aim 2 will use these models to demonstrate that competition for CBP is the rate limiting step in Cr(VI)- induced loss of NF-kappaB transactivation. The consequence of a switch in CBP-dependent transcription factor competence on FAS- induced apoptosis and gene expression will be examined. The final Aim will use normal and unique transgenic mouse models to examine Cr(VI)-induced regulation of transcription factor activity and of inducible pro-apoptotic and pro-fibrotic phenotypic changes in vivo. Significance: The studies will define fundamental epigenetic mechanisms for altered inducible gene expression and increased susceptibility of airway and alveolar epithelial cells to apoptosis following exposure to Cr(VI). Apoptosis of the airway is now recognized as an underlying non-inflammatory mechanism for lung fibrosis. Thus, these studies will translate observations in cell culture into in vivo models of exposure to greatly improve the basic understanding of how Cr(VI) promotes pulmonary diseases.","REGULATION OF TRANSCRIPTIONAL COMPETENCE BY CHROMIUM Abs: Hexavalent chromium (Cr(VI)) is in the top 20 compounds of the ATSDR/EPA priority list since it promotes interstitial lung fibrosis, induces asthma, and is recognized as a probable human lung carcinogen. Despite the epidemiological evidence for both occupationally and environmentally-derived pulmonary disease following inhalation of Cr(VI), there are few studies that define the cellular and molecular basis for pathologic changes in the Cr(VI)-exposed lung. Overall Objective: The overall objective of the proposed studies is to define the molecular signaling mechanisms through which non-cytotoxic concentrations of Cr(VI) alter inducible cytokine and profibrotic gene expression in airway and alveolar epithelial cells. We have recently defined a novel pathway through which Cr(VI) inhibits the transcriptional competence of the transcription factor NF-kappaB by promoting recruitment of the essential co-activator CREB-binding protein (CBP) to c-Jun. We hypothesize that Cr(VI)-induced alteration of co-activator recruitment changes the profile of inducible gene expression and potentiates Fas-induced apoptosis. These effects of Cr(VI) favor development of pulmonary fibrosis. Specific Objectives: Aim 1 of the grant will use human lung cells in culture to define cellular signaling pathways that regulate Cr(VI)-induced recruitment of CBP to specific transcription factors (e.g. c-Jun). Aim 2 will use these models to demonstrate that competition for CBP is the rate limiting step in Cr(VI)- induced loss of NF-kappaB transactivation. The consequence of a switch in CBP-dependent transcription factor competence on FAS- induced apoptosis and gene expression will be examined. The final Aim will use normal and unique transgenic mouse models to examine Cr(VI)-induced regulation of transcription factor activity and of inducible pro-apoptotic and pro-fibrotic phenotypic changes in vivo. Significance: The studies will define fundamental epigenetic mechanisms for altered inducible gene expression and increased susceptibility of airway and alveolar epithelial cells to apoptosis following exposure to Cr(VI). Apoptosis of the airway is now recognized as an underlying non-inflammatory mechanism for lung fibrosis. Thus, these studies will translate observations in cell culture into in vivo models of exposure to greatly improve the basic understanding of how Cr(VI) promotes pulmonary diseases."
1577090,Barchowsky 2003,REGULATION OF TRANSCRIPTIONAL COMPETENCE BY CHROMIUM,"Hexavalent chromium (Cr(VI)) is in the top 20 compounds of the ATSDR/EPA priority list since it promotes interstitial lung fibrosis, induces asthma, and is recognized as a probable human lung carcinogen. Despite the epidemiological evidence for both occupationally and environmentally-derived pulmonary disease following inhalation of Cr(VI), there are few studies that define the cellular and molecular basis for pathologic changes in the Cr(VI)-exposed lung. Overall Objective: The overall objective of the proposed studies is to define the molecular signaling mechanisms through which non-cytotoxic concentrations of Cr(VI) alter inducible cytokine and profibrotic gene expression in airway and alveolar epithelial cells. We have recently defined a novel pathway through which Cr(VI) inhibits the transcriptional competence of the transcription factor NF-kappaB by promoting recruitment of the essential co-activator CREB-binding protein (CBP) to c-Jun. We hypothesize that Cr(VI)-induced alteration of co-activator recruitment changes the profile of inducible gene expression and potentiates Fas-induced apoptosis. These effects of Cr(VI) favor development of pulmonary fibrosis. Specific Objectives: Aim 1 of the grant will use human lung cells in culture to define cellular signaling pathways that regulate Cr(VI)-induced recruitment of CBP to specific transcription factors (e.g. c-Jun). Aim 2 will use these models to demonstrate that competition for CBP is the rate limiting step in Cr(VI)- induced loss of NF-kappaB transactivation. The consequence of a switch in CBP-dependent transcription factor competence on FAS- induced apoptosis and gene expression will be examined. The final Aim will use normal and unique transgenic mouse models to examine Cr(VI)-induced regulation of transcription factor activity and of inducible pro-apoptotic and pro-fibrotic phenotypic changes in vivo. Significance: The studies will define fundamental epigenetic mechanisms for altered inducible gene expression and increased susceptibility of airway and alveolar epithelial cells to apoptosis following exposure to Cr(VI). Apoptosis of the airway is now recognized as an underlying non-inflammatory mechanism for lung fibrosis. Thus, these studies will translate observations in cell culture into in vivo models of exposure to greatly improve the basic understanding of how Cr(VI) promotes pulmonary diseases.","REGULATION OF TRANSCRIPTIONAL COMPETENCE BY CHROMIUM Abs: Hexavalent chromium (Cr(VI)) is in the top 20 compounds of the ATSDR/EPA priority list since it promotes interstitial lung fibrosis, induces asthma, and is recognized as a probable human lung carcinogen. Despite the epidemiological evidence for both occupationally and environmentally-derived pulmonary disease following inhalation of Cr(VI), there are few studies that define the cellular and molecular basis for pathologic changes in the Cr(VI)-exposed lung. Overall Objective: The overall objective of the proposed studies is to define the molecular signaling mechanisms through which non-cytotoxic concentrations of Cr(VI) alter inducible cytokine and profibrotic gene expression in airway and alveolar epithelial cells. We have recently defined a novel pathway through which Cr(VI) inhibits the transcriptional competence of the transcription factor NF-kappaB by promoting recruitment of the essential co-activator CREB-binding protein (CBP) to c-Jun. We hypothesize that Cr(VI)-induced alteration of co-activator recruitment changes the profile of inducible gene expression and potentiates Fas-induced apoptosis. These effects of Cr(VI) favor development of pulmonary fibrosis. Specific Objectives: Aim 1 of the grant will use human lung cells in culture to define cellular signaling pathways that regulate Cr(VI)-induced recruitment of CBP to specific transcription factors (e.g. c-Jun). Aim 2 will use these models to demonstrate that competition for CBP is the rate limiting step in Cr(VI)- induced loss of NF-kappaB transactivation. The consequence of a switch in CBP-dependent transcription factor competence on FAS- induced apoptosis and gene expression will be examined. The final Aim will use normal and unique transgenic mouse models to examine Cr(VI)-induced regulation of transcription factor activity and of inducible pro-apoptotic and pro-fibrotic phenotypic changes in vivo. Significance: The studies will define fundamental epigenetic mechanisms for altered inducible gene expression and increased susceptibility of airway and alveolar epithelial cells to apoptosis following exposure to Cr(VI). Apoptosis of the airway is now recognized as an underlying non-inflammatory mechanism for lung fibrosis. Thus, these studies will translate observations in cell culture into in vivo models of exposure to greatly improve the basic understanding of how Cr(VI) promotes pulmonary diseases."
1577089,Barchowsky 2002,REGULATION OF TRANSCRIPTIONAL COMPETENCE BY CHROMIUM,"Hexavalent chromium (Cr(VI)) is in the top 20 compounds of the ATSDR/EPA priority list since it promotes interstitial lung fibrosis, induces asthma, and is recognized as a probable human lung carcinogen. Despite the epidemiological evidence for both occupationally and environmentally-derived pulmonary disease following inhalation of Cr(VI), there are few studies that define the cellular and molecular basis for pathologic changes in the Cr(VI)-exposed lung. Overall Objective: The overall objective of the proposed studies is to define the molecular signaling mechanisms through which non-cytotoxic concentrations of Cr(VI) alter inducible cytokine and profibrotic gene expression in airway and alveolar epithelial cells. We have recently defined a novel pathway through which Cr(VI) inhibits the transcriptional competence of the transcription factor NF-kappaB by promoting recruitment of the essential co-activator CREB-binding protein (CBP) to c-Jun. We hypothesize that Cr(VI)-induced alteration of co-activator recruitment changes the profile of inducible gene expression and potentiates Fas-induced apoptosis. These effects of Cr(VI) favor development of pulmonary fibrosis. Specific Objectives: Aim 1 of the grant will use human lung cells in culture to define cellular signaling pathways that regulate Cr(VI)-induced recruitment of CBP to specific transcription factors (e.g. c-Jun). Aim 2 will use these models to demonstrate that competition for CBP is the rate limiting step in Cr(VI)- induced loss of NF-kappaB transactivation. The consequence of a switch in CBP-dependent transcription factor competence on FAS- induced apoptosis and gene expression will be examined. The final Aim will use normal and unique transgenic mouse models to examine Cr(VI)-induced regulation of transcription factor activity and of inducible pro-apoptotic and pro-fibrotic phenotypic changes in vivo. Significance: The studies will define fundamental epigenetic mechanisms for altered inducible gene expression and increased susceptibility of airway and alveolar epithelial cells to apoptosis following exposure to Cr(VI). Apoptosis of the airway is now recognized as an underlying non-inflammatory mechanism for lung fibrosis. Thus, these studies will translate observations in cell culture into in vivo models of exposure to greatly improve the basic understanding of how Cr(VI) promotes pulmonary diseases.","REGULATION OF TRANSCRIPTIONAL COMPETENCE BY CHROMIUM Abs: Hexavalent chromium (Cr(VI)) is in the top 20 compounds of the ATSDR/EPA priority list since it promotes interstitial lung fibrosis, induces asthma, and is recognized as a probable human lung carcinogen. Despite the epidemiological evidence for both occupationally and environmentally-derived pulmonary disease following inhalation of Cr(VI), there are few studies that define the cellular and molecular basis for pathologic changes in the Cr(VI)-exposed lung. Overall Objective: The overall objective of the proposed studies is to define the molecular signaling mechanisms through which non-cytotoxic concentrations of Cr(VI) alter inducible cytokine and profibrotic gene expression in airway and alveolar epithelial cells. We have recently defined a novel pathway through which Cr(VI) inhibits the transcriptional competence of the transcription factor NF-kappaB by promoting recruitment of the essential co-activator CREB-binding protein (CBP) to c-Jun. We hypothesize that Cr(VI)-induced alteration of co-activator recruitment changes the profile of inducible gene expression and potentiates Fas-induced apoptosis. These effects of Cr(VI) favor development of pulmonary fibrosis. Specific Objectives: Aim 1 of the grant will use human lung cells in culture to define cellular signaling pathways that regulate Cr(VI)-induced recruitment of CBP to specific transcription factors (e.g. c-Jun). Aim 2 will use these models to demonstrate that competition for CBP is the rate limiting step in Cr(VI)- induced loss of NF-kappaB transactivation. The consequence of a switch in CBP-dependent transcription factor competence on FAS- induced apoptosis and gene expression will be examined. The final Aim will use normal and unique transgenic mouse models to examine Cr(VI)-induced regulation of transcription factor activity and of inducible pro-apoptotic and pro-fibrotic phenotypic changes in vivo. Significance: The studies will define fundamental epigenetic mechanisms for altered inducible gene expression and increased susceptibility of airway and alveolar epithelial cells to apoptosis following exposure to Cr(VI). Apoptosis of the airway is now recognized as an underlying non-inflammatory mechanism for lung fibrosis. Thus, these studies will translate observations in cell culture into in vivo models of exposure to greatly improve the basic understanding of how Cr(VI) promotes pulmonary diseases."
1577088,Barchowsky 2001,REGULATION OF TRANSCRIPTIONAL COMPETENCE BY CHROMIUM,"Hexavalent chromium (Cr(VI)) is in the top 20 compounds of the ATSDR/EPA priority list since it promotes interstitial lung fibrosis, induces asthma, and is recognized as a probable human lung carcinogen. Despite the epidemiological evidence for both occupationally and environmentally-derived pulmonary disease following inhalation of Cr(VI), there are few studies that define the cellular and molecular basis for pathologic changes in the Cr(VI)-exposed lung. Overall Objective: The overall objective of the proposed studies is to define the molecular signaling mechanisms through which non-cytotoxic concentrations of Cr(VI) alter inducible cytokine and profibrotic gene expression in airway and alveolar epithelial cells. We have recently defined a novel pathway through which Cr(VI) inhibits the transcriptional competence of the transcription factor NF-kappaB by promoting recruitment of the essential co-activator CREB-binding protein (CBP) to c-Jun. We hypothesize that Cr(VI)-induced alteration of co-activator recruitment changes the profile of inducible gene expression and potentiates Fas-induced apoptosis. These effects of Cr(VI) favor development of pulmonary fibrosis. Specific Objectives: Aim 1 of the grant will use human lung cells in culture to define cellular signaling pathways that regulate Cr(VI)-induced recruitment of CBP to specific transcription factors (e.g. c-Jun). Aim 2 will use these models to demonstrate that competition for CBP is the rate limiting step in Cr(VI)- induced loss of NF-kappaB transactivation. The consequence of a switch in CBP-dependent transcription factor competence on FAS- induced apoptosis and gene expression will be examined. The final Aim will use normal and unique transgenic mouse models to examine Cr(VI)-induced regulation of transcription factor activity and of inducible pro-apoptotic and pro-fibrotic phenotypic changes in vivo. Significance: The studies will define fundamental epigenetic mechanisms for altered inducible gene expression and increased susceptibility of airway and alveolar epithelial cells to apoptosis following exposure to Cr(VI). Apoptosis of the airway is now recognized as an underlying non-inflammatory mechanism for lung fibrosis. Thus, these studies will translate observations in cell culture into in vivo models of exposure to greatly improve the basic understanding of how Cr(VI) promotes pulmonary diseases.","REGULATION OF TRANSCRIPTIONAL COMPETENCE BY CHROMIUM Abs: Hexavalent chromium (Cr(VI)) is in the top 20 compounds of the ATSDR/EPA priority list since it promotes interstitial lung fibrosis, induces asthma, and is recognized as a probable human lung carcinogen. Despite the epidemiological evidence for both occupationally and environmentally-derived pulmonary disease following inhalation of Cr(VI), there are few studies that define the cellular and molecular basis for pathologic changes in the Cr(VI)-exposed lung. Overall Objective: The overall objective of the proposed studies is to define the molecular signaling mechanisms through which non-cytotoxic concentrations of Cr(VI) alter inducible cytokine and profibrotic gene expression in airway and alveolar epithelial cells. We have recently defined a novel pathway through which Cr(VI) inhibits the transcriptional competence of the transcription factor NF-kappaB by promoting recruitment of the essential co-activator CREB-binding protein (CBP) to c-Jun. We hypothesize that Cr(VI)-induced alteration of co-activator recruitment changes the profile of inducible gene expression and potentiates Fas-induced apoptosis. These effects of Cr(VI) favor development of pulmonary fibrosis. Specific Objectives: Aim 1 of the grant will use human lung cells in culture to define cellular signaling pathways that regulate Cr(VI)-induced recruitment of CBP to specific transcription factors (e.g. c-Jun). Aim 2 will use these models to demonstrate that competition for CBP is the rate limiting step in Cr(VI)- induced loss of NF-kappaB transactivation. The consequence of a switch in CBP-dependent transcription factor competence on FAS- induced apoptosis and gene expression will be examined. The final Aim will use normal and unique transgenic mouse models to examine Cr(VI)-induced regulation of transcription factor activity and of inducible pro-apoptotic and pro-fibrotic phenotypic changes in vivo. Significance: The studies will define fundamental epigenetic mechanisms for altered inducible gene expression and increased susceptibility of airway and alveolar epithelial cells to apoptosis following exposure to Cr(VI). Apoptosis of the airway is now recognized as an underlying non-inflammatory mechanism for lung fibrosis. Thus, these studies will translate observations in cell culture into in vivo models of exposure to greatly improve the basic understanding of how Cr(VI) promotes pulmonary diseases."
1577087,Wise 2005,Toxiology of Particulate Cr(VI)in Human Lung Cells,"Cr(VI) salts, particularly the insoluble compounds, are well-established human carcinogens, affecting the bronchial cells of the lung. No investigations have studied particulate Cr(VI) and only one has studied soluble Cr(VI) in human bronchial cells. Thus the goal of this research is to understand the mechanisms of Cr(VI)-induced carcinogenesis in human bronchial cells. The general hypothesis guiding this proposal is that particulate Cr(VI) is a more potent carcinogen than soluble Cr(VI) because it can escape cell cycle arrest at genotoxic doses. The specific goal of this project is to establish a human bronchial cell model to investigate these mechanisms. Three hypotheses will be tested: 1) Cr(VI) is genotoxic in human bronchial cells. 2) Particulate Cr(VI) compounds are more potent carcinogens than soluble Cr(VI) compounds because they provide chronic extracellular Cr(VI) exposure and escape cell cycle delay. 3) Particulate Cr(VI) salts escape cell cycle delay because of their divalent counter ion. These hypotheses will be tested with the following: 1) Cr(VI)-induced genotoxicity will be measured by the amount of damage produced in the Comet assay, and in metaphase chromosome spreads. Results will provide the first data on the carcinogenic and genotoxic effects of intact Cr(VI) particles to its target cells. 2) Particle uptake will be measured with transmission electron microscopy and ion uptake will be measured with inductively coupled plasma mass spectrometry. 3). Cell cycle effects will be measured with a mitotic index, fluorescent automated cell sorting and cDNA expression arrays. Results will the first reports of Cr(VI) toxicity in its target cells, the first detailed information of the interaction of Cr(VI) with the cell cycle, and will provide important toxicological data on the differences between particulate and soluble hexavalent chromium. This research is significant because it will provide: 1) an understanding of how Cr(VI) causes genetic in its target cells; 2) essential information to better assess the relative risk of exposure to particulate or soluble Cr(VI); 3) models of human bronchial cells for further study of Cr(VI), other metals, and lung cancer in general.","Toxiology of Particulate Cr(VI)in Human Lung Cells Abs: Cr(VI) salts, particularly the insoluble compounds, are well-established human carcinogens, affecting the bronchial cells of the lung. No investigations have studied particulate Cr(VI) and only one has studied soluble Cr(VI) in human bronchial cells. Thus the goal of this research is to understand the mechanisms of Cr(VI)-induced carcinogenesis in human bronchial cells. The general hypothesis guiding this proposal is that particulate Cr(VI) is a more potent carcinogen than soluble Cr(VI) because it can escape cell cycle arrest at genotoxic doses. The specific goal of this project is to establish a human bronchial cell model to investigate these mechanisms. Three hypotheses will be tested: 1) Cr(VI) is genotoxic in human bronchial cells. 2) Particulate Cr(VI) compounds are more potent carcinogens than soluble Cr(VI) compounds because they provide chronic extracellular Cr(VI) exposure and escape cell cycle delay. 3) Particulate Cr(VI) salts escape cell cycle delay because of their divalent counter ion. These hypotheses will be tested with the following: 1) Cr(VI)-induced genotoxicity will be measured by the amount of damage produced in the Comet assay, and in metaphase chromosome spreads. Results will provide the first data on the carcinogenic and genotoxic effects of intact Cr(VI) particles to its target cells. 2) Particle uptake will be measured with transmission electron microscopy and ion uptake will be measured with inductively coupled plasma mass spectrometry. 3). Cell cycle effects will be measured with a mitotic index, fluorescent automated cell sorting and cDNA expression arrays. Results will the first reports of Cr(VI) toxicity in its target cells, the first detailed information of the interaction of Cr(VI) with the cell cycle, and will provide important toxicological data on the differences between particulate and soluble hexavalent chromium. This research is significant because it will provide: 1) an understanding of how Cr(VI) causes genetic in its target cells; 2) essential information to better assess the relative risk of exposure to particulate or soluble Cr(VI); 3) models of human bronchial cells for further study of Cr(VI), other metals, and lung cancer in general."
1577086,Jolly 2005,Proactive Prevention of Exposure Respirable Chromium,"DESCRIPTION (provided by applicant): Occupational exposures to hexavalent chromium, Cr(VI), occur during the production and use of stainless steel, chromate chemicals, and chromate pigments and operations such as chrome plating and coating processes. NIOSH considers all Cr(VI) compounds to be potential occupational carcinogens, and an increased risk of lung cancer has been demonstrated in exposed workers. Compliance with occupational exposure protection requirements for toxic metals is currently very difficult for industrial and government facilities to achieve. The purpose of this program is to create an automated, low-cost method for rapidly quantifying potential exposures to chromium via respiratory pathways. This will be accomplished by developing and field-testing analytical instrumentation and methodology to assist facilities in reducing the potential for occupational exposures to airborne chromium. The ultimate goal of the program is the creation of approved NIOSH and ASTM methods for automated airborne chromium analysis using ultrasonic extraction and adsorptive stripping voltammetry. This research plan is expected to firmly establish the technical basis for the new method, and will provide a capability in this field that does not currently exist. The potential for commercial application of this technology is extremely high due to its excellent sensitivity, rapid sample turnaround time, and low cost. All instrument functions are performed automatically, which differentiates the approach from any other method, and projects to a much more user-friendly design for use by industrial and government facilities. This program will also be instrumental in supporting the broader objective of developing a series of approved methods for automated monitoring and rapid analysis of other metals that pose health risks in occupational environments. A series of analyzers and methods based on ultrasonic extraction/electrochemical detection techniques is envisioned, which broadens the impact beyond chromium and supports the goal of effective, low-cost methods for the entire range of toxic respirable metals.","Proactive Prevention of Exposure Respirable Chromium Abs: DESCRIPTION (provided by applicant): Occupational exposures to hexavalent chromium, Cr(VI), occur during the production and use of stainless steel, chromate chemicals, and chromate pigments and operations such as chrome plating and coating processes. NIOSH considers all Cr(VI) compounds to be potential occupational carcinogens, and an increased risk of lung cancer has been demonstrated in exposed workers. Compliance with occupational exposure protection requirements for toxic metals is currently very difficult for industrial and government facilities to achieve. The purpose of this program is to create an automated, low-cost method for rapidly quantifying potential exposures to chromium via respiratory pathways. This will be accomplished by developing and field-testing analytical instrumentation and methodology to assist facilities in reducing the potential for occupational exposures to airborne chromium. The ultimate goal of the program is the creation of approved NIOSH and ASTM methods for automated airborne chromium analysis using ultrasonic extraction and adsorptive stripping voltammetry. This research plan is expected to firmly establish the technical basis for the new method, and will provide a capability in this field that does not currently exist. The potential for commercial application of this technology is extremely high due to its excellent sensitivity, rapid sample turnaround time, and low cost. All instrument functions are performed automatically, which differentiates the approach from any other method, and projects to a much more user-friendly design for use by industrial and government facilities. This program will also be instrumental in supporting the broader objective of developing a series of approved methods for automated monitoring and rapid analysis of other metals that pose health risks in occupational environments. A series of analyzers and methods based on ultrasonic extraction/electrochemical detection techniques is envisioned, which broadens the impact beyond chromium and supports the goal of effective, low-cost methods for the entire range of toxic respirable metals."
1577085,Zhitkovich 2005,Sensitivity Mechanisms in Chromium Toxicity,"DESCRIPTION (provided by applicant): Hexavalent chromium (CrVI) is a toxic DNA-damaging agent with a well-documented exposure in a large number of occupations, and it is a common environmental contaminant. Cr(VI) is listed by the ATSDR and EPA as one of the top 20 high priority toxic agents. The final oxidative form of Cr in biological systems is Cr(lll) that produces several stable DNA adducts. We have recently found that Cr(III)-DNA adducts are one of the major causes of mutagenicity of Cr(VI). Our new data indicate that Cr-DNA adducts also play an important role in toxicity of Cr(VI). Toxic responses to Cr-DNA adducts were strongly dependent on the presence of a small group of proteins that bind to Cr-damaged chromatin. This proposal is designed to test our working hypothesis that cytotoxic effects of Cr-DNA adducts are caused by the formation of secondary DNA lesions generated as a result of the recognition and processing of adducts by damage sensory proteins. Biochemical approaches and cellular models with downregulated levels of damage-processing proteins will be used to gain evidence supporting the proposed hypothesis. We constructed a series of the retroviral siRNA-encoding vectors, which will allow us to examine the role of various proteins in the cytotoxic responses in the target primary human bronchial epithelial cells that have not been previously amenable to the mechanistic studies. The results of this work are expected to advance molecular understanding of Cr(VI) injury in the major target cells and to identify damage processing proteins that enhance toxicity of Cr-DNA modifications.","Sensitivity Mechanisms in Chromium Toxicity Abs: DESCRIPTION (provided by applicant): Hexavalent chromium (CrVI) is a toxic DNA-damaging agent with a well-documented exposure in a large number of occupations, and it is a common environmental contaminant. Cr(VI) is listed by the ATSDR and EPA as one of the top 20 high priority toxic agents. The final oxidative form of Cr in biological systems is Cr(lll) that produces several stable DNA adducts. We have recently found that Cr(III)-DNA adducts are one of the major causes of mutagenicity of Cr(VI). Our new data indicate that Cr-DNA adducts also play an important role in toxicity of Cr(VI). Toxic responses to Cr-DNA adducts were strongly dependent on the presence of a small group of proteins that bind to Cr-damaged chromatin. This proposal is designed to test our working hypothesis that cytotoxic effects of Cr-DNA adducts are caused by the formation of secondary DNA lesions generated as a result of the recognition and processing of adducts by damage sensory proteins. Biochemical approaches and cellular models with downregulated levels of damage-processing proteins will be used to gain evidence supporting the proposed hypothesis. We constructed a series of the retroviral siRNA-encoding vectors, which will allow us to examine the role of various proteins in the cytotoxic responses in the target primary human bronchial epithelial cells that have not been previously amenable to the mechanistic studies. The results of this work are expected to advance molecular understanding of Cr(VI) injury in the major target cells and to identify damage processing proteins that enhance toxicity of Cr-DNA modifications."
1577084,Xu 2005,ATM and ATR in chromium-induced S-phase arrest,"DESCRIPTION (provided by applicant): Hexavalent chromium (Cr [VI]) is a common industrial waste product and an environmental pollutant, and it is a known human carcinogen. Cr (VI) compounds are metabolized to pentavalent (Cr [V]), tetravalent (Cr [IV]), and trivalent (Cr [III]) chromium once they enter the body. Cr (V) and Cr (IV) are highly reactive intermediates and have been shown to cause several types of DNA damage. Exposure to Cr compounds triggers the S-phase cell cycle checkpoint, an active cellular response which may enhance cell survival and limit heritable genetic abnormalities in the presence of DNA damage. Characterization of biochemical steps in Cr-induced S-phase arrest will help improve our understanding of mechanisms of Cr-induced tumorigenesis. The stimulus for proposing the experiments in this application is our preliminary observations that Ataxia-Telangiectasia-Mutated protein kinase (ATM) and its related kinase ATR are required for Cr-induced intra S-phase arrest. ATM and ATR belong to a structurally unique family of protein serine-threonine kinases whose catalytic domains share a clear evolutionary relationship with those of mammalian and yeast phosphoinositide 3-kinases. Both ATM and ATR are critical for cellular response to DNA damage. Our preliminary data has revealed that exposure to Cr (VI), and its metabolic byproducts Cr (V) and Cr (IV), induces measurable DNA double strand breaks. However, only Cr (V) and Cr (VI), but not Cr (IV), can activate intra S-phase checkpoint and ATM kinase. The Cr-induced S-phase arrest is both ATM- and ATR-dependent. Furthermore, we found that the Structural Maintenance of Chromosomal protein 1 (SMC 1) is phosphorylated in an ATM-dependent manner after low dose Cr exposure. The proposed experiments will investigate how ATM and ATR regulate S-phase arrest after exposure to Cr and identify molecular determinants of the process. In specific aim 1, we will investigate whether NBS 1 and BRCA1, both of which are ATM substrates in response to DNA damage, are required for the ATM-dependent process. We will also study the functional significance of ATM phosphorylation of SMC 1 in response to Cr exposure. In specific aim 2, we will study whether ATR is activated by exposure to Cr and whether SMC 1 is a downstream target of ATR in regulating the checkpoint. Our long-term goal is to better understand the mechanisms by which mammalian cells respond to Cr exposure and the role of ATM and ATR in the pathway as a basis for providing insights into general mechanisms of carcinogenesis, cell growth and cell death.","ATM and ATR in chromium-induced S-phase arrest Abs: DESCRIPTION (provided by applicant): Hexavalent chromium (Cr [VI]) is a common industrial waste product and an environmental pollutant, and it is a known human carcinogen. Cr (VI) compounds are metabolized to pentavalent (Cr [V]), tetravalent (Cr [IV]), and trivalent (Cr [III]) chromium once they enter the body. Cr (V) and Cr (IV) are highly reactive intermediates and have been shown to cause several types of DNA damage. Exposure to Cr compounds triggers the S-phase cell cycle checkpoint, an active cellular response which may enhance cell survival and limit heritable genetic abnormalities in the presence of DNA damage. Characterization of biochemical steps in Cr-induced S-phase arrest will help improve our understanding of mechanisms of Cr-induced tumorigenesis. The stimulus for proposing the experiments in this application is our preliminary observations that Ataxia-Telangiectasia-Mutated protein kinase (ATM) and its related kinase ATR are required for Cr-induced intra S-phase arrest. ATM and ATR belong to a structurally unique family of protein serine-threonine kinases whose catalytic domains share a clear evolutionary relationship with those of mammalian and yeast phosphoinositide 3-kinases. Both ATM and ATR are critical for cellular response to DNA damage. Our preliminary data has revealed that exposure to Cr (VI), and its metabolic byproducts Cr (V) and Cr (IV), induces measurable DNA double strand breaks. However, only Cr (V) and Cr (VI), but not Cr (IV), can activate intra S-phase checkpoint and ATM kinase. The Cr-induced S-phase arrest is both ATM- and ATR-dependent. Furthermore, we found that the Structural Maintenance of Chromosomal protein 1 (SMC 1) is phosphorylated in an ATM-dependent manner after low dose Cr exposure. The proposed experiments will investigate how ATM and ATR regulate S-phase arrest after exposure to Cr and identify molecular determinants of the process. In specific aim 1, we will investigate whether NBS 1 and BRCA1, both of which are ATM substrates in response to DNA damage, are required for the ATM-dependent process. We will also study the functional significance of ATM phosphorylation of SMC 1 in response to Cr exposure. In specific aim 2, we will study whether ATR is activated by exposure to Cr and whether SMC 1 is a downstream target of ATR in regulating the checkpoint. Our long-term goal is to better understand the mechanisms by which mammalian cells respond to Cr exposure and the role of ATM and ATR in the pathway as a basis for providing insights into general mechanisms of carcinogenesis, cell growth and cell death."
1577083,Zhitkovich 2005,Biological Dosimetry of Hexavalent Chromium,"Chromium and its compounds are major contaminants at a large number of the Superfund sites. Chromium exists in several oxidation states, among which only hexavalent form is associated with carcinogenic and other toxic effects of this metal. Superfund sites and other sources of environmental contamination usually contain chromium in different oxidation forms, which makes it difficult to assess human exposure to toxic chromium(VI) based on total levels of chromium in biological samples. We have previously determined that the most abundant form of DMA damage in chromium(VI)-exposed cells are mutagenic ternary chromium- DNA complexes containing ascorbate and amino acid/peptide ligands. In this work we propose to characterize the use of measurements of ternary adducts as a biomarker of genetic damage by chromium(VI) in human cells. Experiments will be performed to identify slowly repairable forms of chromium-DNA adducts, the role of biological repair and ligand exchange-dependent loss, the influence of co-exposure to other metals on biological characteristics of chromium-DNA adducts and to develop a more sensitive analytical methodology for the determination of major mutagenic chromium-DNA modifications.","Biological Dosimetry of Hexavalent Chromium Abs: Chromium and its compounds are major contaminants at a large number of the Superfund sites. Chromium exists in several oxidation states, among which only hexavalent form is associated with carcinogenic and other toxic effects of this metal. Superfund sites and other sources of environmental contamination usually contain chromium in different oxidation forms, which makes it difficult to assess human exposure to toxic chromium(VI) based on total levels of chromium in biological samples. We have previously determined that the most abundant form of DMA damage in chromium(VI)-exposed cells are mutagenic ternary chromium- DNA complexes containing ascorbate and amino acid/peptide ligands. In this work we propose to characterize the use of measurements of ternary adducts as a biomarker of genetic damage by chromium(VI) in human cells. Experiments will be performed to identify slowly repairable forms of chromium-DNA adducts, the role of biological repair and ligand exchange-dependent loss, the influence of co-exposure to other metals on biological characteristics of chromium-DNA adducts and to develop a more sensitive analytical methodology for the determination of major mutagenic chromium-DNA modifications."
1577082,Ceryak 2006,Survival Signaling After Genotoxic Insult,"DESCRIPTION (provided by applicant): Inappropriate activation/inactivation of key signals that control cell survival after genotoxic insult can contribute to autonomous growth and neoplastic transformation. An initial consequence of genotoxic injury is cell cycle checkpoint arrest but genotoxicity may also activate cell death pathways of apoptosis or terminal growth arrest. Cellular survival responses to genotoxic insult may produce intrinsic death-resistance; such a selective growth advantage may allow for emergence of a transformed phenotype. Certain forms of hexavalent chromium [(Cr(VI)] are known human respiratory carcinogens that can be employed as useful genotoxic tools with relevant toxicological importance. Our preliminary studies suggest that maintenance of protein tyrosine phosphorylation, which is coincident with AKT activation, overrides Cr-induced growth arrest and enhances clonogenic survival. Constitutive AKT activation is known to play an important role in carcinogenesis. Therefore, the overall objective of this proposal is to elucidate the coordinate signaling events that mediate cell fate determination and survival after genotoxic insult. The dual overarching hypotheses of the proposed studies are that: 1) AKT activation shifts the balance of cell fates, toward survival, after Cr(Vl) genotoxic insult; and 2) AKT activation in the face of Cr(Vl) genotoxic insult increases genomic instability. To test these hypotheses, we will employ molecular, pharmacological and genetic approaches, by using relevant model systems of human diploid lung fibroblasts (HLF), and human large airway epithelial cells (HLAE) and studying the involvement of key signaling components of the AKT pathway. The molecular circuitry of the AKT effect will be delineated in Aim 1, and the consequences of an AKT-induced ""override"" of the genotoxin-elicited program of cell death will be investigated in Aim 2. Aim 3 will identify the role of AKT in resistance to Cr(Vl)-induced clonogenic lethality in a subclonal population of cells with acquired resistance to Cr-induced clonogenic death. We will use soluble Na2CrO4 at a range of concentrations relevant to human exposure, and for which the DNA adduct frequencies and genotoxic lesions are well documented. Results of the proposed studies will identify molecular mechanism(s) that confer a growth advantage to cells after genotoxic insult, and add new insights to the understanding of Cr(Vl)-induced lung carcinogenesis, while addressing a need for sensitive and specific molecular indices that can be correlated with exposure to carcinogenic agents, as well as with their cancer incidence. Delineation of the molecular circuitry involved in AKT survival signaling may have the added benefit of identifying molecular targets for rational drug design in anti-cancer therapy.","Survival Signaling After Genotoxic Insult Abs: DESCRIPTION (provided by applicant): Inappropriate activation/inactivation of key signals that control cell survival after genotoxic insult can contribute to autonomous growth and neoplastic transformation. An initial consequence of genotoxic injury is cell cycle checkpoint arrest but genotoxicity may also activate cell death pathways of apoptosis or terminal growth arrest. Cellular survival responses to genotoxic insult may produce intrinsic death-resistance; such a selective growth advantage may allow for emergence of a transformed phenotype. Certain forms of hexavalent chromium [(Cr(VI)] are known human respiratory carcinogens that can be employed as useful genotoxic tools with relevant toxicological importance. Our preliminary studies suggest that maintenance of protein tyrosine phosphorylation, which is coincident with AKT activation, overrides Cr-induced growth arrest and enhances clonogenic survival. Constitutive AKT activation is known to play an important role in carcinogenesis. Therefore, the overall objective of this proposal is to elucidate the coordinate signaling events that mediate cell fate determination and survival after genotoxic insult. The dual overarching hypotheses of the proposed studies are that: 1) AKT activation shifts the balance of cell fates, toward survival, after Cr(Vl) genotoxic insult; and 2) AKT activation in the face of Cr(Vl) genotoxic insult increases genomic instability. To test these hypotheses, we will employ molecular, pharmacological and genetic approaches, by using relevant model systems of human diploid lung fibroblasts (HLF), and human large airway epithelial cells (HLAE) and studying the involvement of key signaling components of the AKT pathway. The molecular circuitry of the AKT effect will be delineated in Aim 1, and the consequences of an AKT-induced ""override"" of the genotoxin-elicited program of cell death will be investigated in Aim 2. Aim 3 will identify the role of AKT in resistance to Cr(Vl)-induced clonogenic lethality in a subclonal population of cells with acquired resistance to Cr-induced clonogenic death. We will use soluble Na2CrO4 at a range of concentrations relevant to human exposure, and for which the DNA adduct frequencies and genotoxic lesions are well documented. Results of the proposed studies will identify molecular mechanism(s) that confer a growth advantage to cells after genotoxic insult, and add new insights to the understanding of Cr(Vl)-induced lung carcinogenesis, while addressing a need for sensitive and specific molecular indices that can be correlated with exposure to carcinogenic agents, as well as with their cancer incidence. Delineation of the molecular circuitry involved in AKT survival signaling may have the added benefit of identifying molecular targets for rational drug design in anti-cancer therapy."
1577081,Zhitkovich 2006,Genotoxicity of Chromium Compounds,"DESCRIPTION (provided by applicant): Carcinogenic activity of hexavalent chromium (Cr) compounds is firmly established by experimental and epidemiological studies. Human exposure to Cr(VI) is found in several dozen occupations and detected in populations residing in the vicinity of Cr-emitting industrial sources and Cr disposal sites. Cr(Vl) is a major air pollutant and a Superfund contaminant. The major form of DNA damage in Cr(VI)-exposed cells is abundant Cr-DNA adducts generated in the reactions of stable Cr(III) form with DNA phosphates. We have found that several Cr-DNA adducts were mutagenic during replication in human cells. Ternary DNA adducts containing bulky ligands, such as glutathione or ascorbate, induced the strongest mutagenic responses. We also determined that Cr(III)-dependent reactions were responsible for the formation of mutagenic DNA damage during reductive activation of Cr(VI) by its major biological reducers, cysteine and ascorbate. Additional data have shown that biological consequences of the formation of Cr(III)-DNA adducts are strongly influenced by the status of DNA mismatch repair system. We propose to elucidate the mechanisms of mismatch repair-dependent induction of stress signaling and formation of genetic alterations in Cr(VI)- exposed cells. Experiments will be performed to identify specific Cr-DNA adducts that are recognized by DNA mismatch repair and activate genotoxic responses. The results of this work should provide a greater understanding of molecular basis of Cr(VI) carcinogenesis, the importance of individual Cr-DNA adducts and uncover new functions of mismatch repair in recognition of DNA backbone modifications. Identification of the most potent genotoxic Cr-DNA adducts and critical pathways controlling cellular responses to Cr(VI) can be used in the development of useful biomarkers of exposure and individual susceptibility to adverse health effects.","Genotoxicity of Chromium Compounds Abs: DESCRIPTION (provided by applicant): Carcinogenic activity of hexavalent chromium (Cr) compounds is firmly established by experimental and epidemiological studies. Human exposure to Cr(VI) is found in several dozen occupations and detected in populations residing in the vicinity of Cr-emitting industrial sources and Cr disposal sites. Cr(Vl) is a major air pollutant and a Superfund contaminant. The major form of DNA damage in Cr(VI)-exposed cells is abundant Cr-DNA adducts generated in the reactions of stable Cr(III) form with DNA phosphates. We have found that several Cr-DNA adducts were mutagenic during replication in human cells. Ternary DNA adducts containing bulky ligands, such as glutathione or ascorbate, induced the strongest mutagenic responses. We also determined that Cr(III)-dependent reactions were responsible for the formation of mutagenic DNA damage during reductive activation of Cr(VI) by its major biological reducers, cysteine and ascorbate. Additional data have shown that biological consequences of the formation of Cr(III)-DNA adducts are strongly influenced by the status of DNA mismatch repair system. We propose to elucidate the mechanisms of mismatch repair-dependent induction of stress signaling and formation of genetic alterations in Cr(VI)- exposed cells. Experiments will be performed to identify specific Cr-DNA adducts that are recognized by DNA mismatch repair and activate genotoxic responses. The results of this work should provide a greater understanding of molecular basis of Cr(VI) carcinogenesis, the importance of individual Cr-DNA adducts and uncover new functions of mismatch repair in recognition of DNA backbone modifications. Identification of the most potent genotoxic Cr-DNA adducts and critical pathways controlling cellular responses to Cr(VI) can be used in the development of useful biomarkers of exposure and individual susceptibility to adverse health effects."
1577080,Costa 2006,Detection of Cr- DNA adducts in human,"Hexavalent chromium is a well established human carcinogen and is a contaminant at numerous Superfund toxic waste dump sites. Carcinogenesis by hexavalent chromium is thought to involve the formation of Cr-DNA adducts. About 50% of the chromium is bound to DNA as ternary complexes of Cr (III) with either amino acids or glutathione. Additionally, hexavalent chromium has been shown to interact with DNA in a non-random fashion targeting itself to promoters and coding regions of highly inducible genes. Previous studies in humans have suggested that there is a large intra-individual variability in the uptake of chromate. Using he bacterial repair enzymes UvrABC and the technique of ligation-mediated PCR, we will study whether the UvrABC bacterial enzymes can detect and differentiate Cr-DNA complexes including Cr(III)-DNA binary, as well as (Cr(III)-DNA ternary complexes involving either cysteine, histidine, or glutathione within exon 7 of the p53 gene. We will also investigate the effect of cytosine methylation on the formation of adducts in human lymphocytes following exposure to hexavalent chromium within other DNA regions that we can analyze for hotspots of Cr-DNA adducts. Bacterial repair enzymes will cut at Cr adducts, and Southern blotting will measure the hybridization signal in the cut region compared to the uncut DNA using probes, such as the ornithine decarboxylase (ODC) promoter and the p53 coding regions. We will examine hexavalent chromium uptake in 60 human volunteers and identify those with the highest uptake capacity and highest intracellular levels of chromium and high chromate uptake will be utilized to map the Cr-DNA adducts at a single nucleotide level in p53 exon 5 and 7, as well as other DNA regions. These studies attempt to develop biomarkers of exposure and effect of carcinogenic hexavalent chromium. We consider important parameters of genetic diversity including epigenetic differences in DNA methylation and the interindividual diversity of chromatic uptake into cells. These studies should lead to new methodologies for assessing the impact of environmental exposure of hexavalent chromium to the human population and identify factors of susceptibility that enhance Cr toxicity.","Detection of Cr- DNA adducts in human Abs: Hexavalent chromium is a well established human carcinogen and is a contaminant at numerous Superfund toxic waste dump sites. Carcinogenesis by hexavalent chromium is thought to involve the formation of Cr-DNA adducts. About 50% of the chromium is bound to DNA as ternary complexes of Cr (III) with either amino acids or glutathione. Additionally, hexavalent chromium has been shown to interact with DNA in a non-random fashion targeting itself to promoters and coding regions of highly inducible genes. Previous studies in humans have suggested that there is a large intra-individual variability in the uptake of chromate. Using he bacterial repair enzymes UvrABC and the technique of ligation-mediated PCR, we will study whether the UvrABC bacterial enzymes can detect and differentiate Cr-DNA complexes including Cr(III)-DNA binary, as well as (Cr(III)-DNA ternary complexes involving either cysteine, histidine, or glutathione within exon 7 of the p53 gene. We will also investigate the effect of cytosine methylation on the formation of adducts in human lymphocytes following exposure to hexavalent chromium within other DNA regions that we can analyze for hotspots of Cr-DNA adducts. Bacterial repair enzymes will cut at Cr adducts, and Southern blotting will measure the hybridization signal in the cut region compared to the uncut DNA using probes, such as the ornithine decarboxylase (ODC) promoter and the p53 coding regions. We will examine hexavalent chromium uptake in 60 human volunteers and identify those with the highest uptake capacity and highest intracellular levels of chromium and high chromate uptake will be utilized to map the Cr-DNA adducts at a single nucleotide level in p53 exon 5 and 7, as well as other DNA regions. These studies attempt to develop biomarkers of exposure and effect of carcinogenic hexavalent chromium. We consider important parameters of genetic diversity including epigenetic differences in DNA methylation and the interindividual diversity of chromatic uptake into cells. These studies should lead to new methodologies for assessing the impact of environmental exposure of hexavalent chromium to the human population and identify factors of susceptibility that enhance Cr toxicity."
1577079,Jolly 2006,Proactive Prevention of Exposure Respirable Chromium,"DESCRIPTION (provided by applicant): Occupational exposures to hexavalent chromium, Cr(VI), occur during the production and use of stainless steel, chromate chemicals, and chromate pigments and operations such as chrome plating and coating processes. NIOSH considers all Cr(VI) compounds to be potential occupational carcinogens, and an increased risk of lung cancer has been demonstrated in exposed workers. Compliance with occupational exposure protection requirements for toxic metals is currently very difficult for industrial and government facilities to achieve. The purpose of this program is to create an automated, low-cost method for rapidly quantifying potential exposures to chromium via respiratory pathways. This will be accomplished by developing and field-testing analytical instrumentation and methodology to assist facilities in reducing the potential for occupational exposures to airborne chromium. The ultimate goal of the program is the creation of approved NIOSH and ASTM methods for automated airborne chromium analysis using ultrasonic extraction and adsorptive stripping voltammetry. This research plan is expected to firmly establish the technical basis for the new method, and will provide a capability in this field that does not currently exist. The potential for commercial application of this technology is extremely high due to its excellent sensitivity, rapid sample turnaround time, and low cost. All instrument functions are performed automatically, which differentiates the approach from any other method, and projects to a much more user-friendly design for use by industrial and government facilities. This program will also be instrumental in supporting the broader objective of developing a series of approved methods for automated monitoring and rapid analysis of other metals that pose health risks in occupational environments. A series of analyzers and methods based on ultrasonic extraction/electrochemical detection techniques is envisioned, which broadens the impact beyond chromium and supports the goal of effective, low-cost methods for the entire range of toxic respirable metals.","Proactive Prevention of Exposure Respirable Chromium Abs: DESCRIPTION (provided by applicant): Occupational exposures to hexavalent chromium, Cr(VI), occur during the production and use of stainless steel, chromate chemicals, and chromate pigments and operations such as chrome plating and coating processes. NIOSH considers all Cr(VI) compounds to be potential occupational carcinogens, and an increased risk of lung cancer has been demonstrated in exposed workers. Compliance with occupational exposure protection requirements for toxic metals is currently very difficult for industrial and government facilities to achieve. The purpose of this program is to create an automated, low-cost method for rapidly quantifying potential exposures to chromium via respiratory pathways. This will be accomplished by developing and field-testing analytical instrumentation and methodology to assist facilities in reducing the potential for occupational exposures to airborne chromium. The ultimate goal of the program is the creation of approved NIOSH and ASTM methods for automated airborne chromium analysis using ultrasonic extraction and adsorptive stripping voltammetry. This research plan is expected to firmly establish the technical basis for the new method, and will provide a capability in this field that does not currently exist. The potential for commercial application of this technology is extremely high due to its excellent sensitivity, rapid sample turnaround time, and low cost. All instrument functions are performed automatically, which differentiates the approach from any other method, and projects to a much more user-friendly design for use by industrial and government facilities. This program will also be instrumental in supporting the broader objective of developing a series of approved methods for automated monitoring and rapid analysis of other metals that pose health risks in occupational environments. A series of analyzers and methods based on ultrasonic extraction/electrochemical detection techniques is envisioned, which broadens the impact beyond chromium and supports the goal of effective, low-cost methods for the entire range of toxic respirable metals."
1577078,Zhitkovich 2006,Sensitivity Mechanisms in Chromium Toxicity,"DESCRIPTION (provided by applicant): Hexavalent chromium (CrVI) is a toxic DNA-damaging agent with a well-documented exposure in a large number of occupations, and it is a common environmental contaminant. Cr(VI) is listed by the ATSDR and EPA as one of the top 20 high priority toxic agents. The final oxidative form of Cr in biological systems is Cr(lll) that produces several stable DNA adducts. We have recently found that Cr(III)-DNA adducts are one of the major causes of mutagenicity of Cr(VI). Our new data indicate that Cr-DNA adducts also play an important role in toxicity of Cr(VI). Toxic responses to Cr-DNA adducts were strongly dependent on the presence of a small group of proteins that bind to Cr-damaged chromatin. This proposal is designed to test our working hypothesis that cytotoxic effects of Cr-DNA adducts are caused by the formation of secondary DNA lesions generated as a result of the recognition and processing of adducts by damage sensory proteins. Biochemical approaches and cellular models with downregulated levels of damage-processing proteins will be used to gain evidence supporting the proposed hypothesis. We constructed a series of the retroviral siRNA-encoding vectors, which will allow us to examine the role of various proteins in the cytotoxic responses in the target primary human bronchial epithelial cells that have not been previously amenable to the mechanistic studies. The results of this work are expected to advance molecular understanding of Cr(VI) injury in the major target cells and to identify damage processing proteins that enhance toxicity of Cr-DNA modifications.","Sensitivity Mechanisms in Chromium Toxicity Abs: DESCRIPTION (provided by applicant): Hexavalent chromium (CrVI) is a toxic DNA-damaging agent with a well-documented exposure in a large number of occupations, and it is a common environmental contaminant. Cr(VI) is listed by the ATSDR and EPA as one of the top 20 high priority toxic agents. The final oxidative form of Cr in biological systems is Cr(lll) that produces several stable DNA adducts. We have recently found that Cr(III)-DNA adducts are one of the major causes of mutagenicity of Cr(VI). Our new data indicate that Cr-DNA adducts also play an important role in toxicity of Cr(VI). Toxic responses to Cr-DNA adducts were strongly dependent on the presence of a small group of proteins that bind to Cr-damaged chromatin. This proposal is designed to test our working hypothesis that cytotoxic effects of Cr-DNA adducts are caused by the formation of secondary DNA lesions generated as a result of the recognition and processing of adducts by damage sensory proteins. Biochemical approaches and cellular models with downregulated levels of damage-processing proteins will be used to gain evidence supporting the proposed hypothesis. We constructed a series of the retroviral siRNA-encoding vectors, which will allow us to examine the role of various proteins in the cytotoxic responses in the target primary human bronchial epithelial cells that have not been previously amenable to the mechanistic studies. The results of this work are expected to advance molecular understanding of Cr(VI) injury in the major target cells and to identify damage processing proteins that enhance toxicity of Cr-DNA modifications."
1577077,Zhitkovich 2007,Genotoxicity of Chromium Compounds,"DESCRIPTION (provided by applicant): Carcinogenic activity of hexavalent chromium (Cr) compounds is firmly established by experimental and epidemiological studies. Human exposure to Cr(VI) is found in several dozen occupations and detected in populations residing in the vicinity of Cr-emitting industrial sources and Cr disposal sites. Cr(Vl) is a major air pollutant and a Superfund contaminant. The major form of DNA damage in Cr(VI)-exposed cells is abundant Cr-DNA adducts generated in the reactions of stable Cr(III) form with DNA phosphates. We have found that several Cr-DNA adducts were mutagenic during replication in human cells. Ternary DNA adducts containing bulky ligands, such as glutathione or ascorbate, induced the strongest mutagenic responses. We also determined that Cr(III)-dependent reactions were responsible for the formation of mutagenic DNA damage during reductive activation of Cr(VI) by its major biological reducers, cysteine and ascorbate. Additional data have shown that biological consequences of the formation of Cr(III)-DNA adducts are strongly influenced by the status of DNA mismatch repair system. We propose to elucidate the mechanisms of mismatch repair-dependent induction of stress signaling and formation of genetic alterations in Cr(VI)- exposed cells. Experiments will be performed to identify specific Cr-DNA adducts that are recognized by DNA mismatch repair and activate genotoxic responses. The results of this work should provide a greater understanding of molecular basis of Cr(VI) carcinogenesis, the importance of individual Cr-DNA adducts and uncover new functions of mismatch repair in recognition of DNA backbone modifications. Identification of the most potent genotoxic Cr-DNA adducts and critical pathways controlling cellular responses to Cr(VI) can be used in the development of useful biomarkers of exposure and individual susceptibility to adverse health effects.","Genotoxicity of Chromium Compounds Abs: DESCRIPTION (provided by applicant): Carcinogenic activity of hexavalent chromium (Cr) compounds is firmly established by experimental and epidemiological studies. Human exposure to Cr(VI) is found in several dozen occupations and detected in populations residing in the vicinity of Cr-emitting industrial sources and Cr disposal sites. Cr(Vl) is a major air pollutant and a Superfund contaminant. The major form of DNA damage in Cr(VI)-exposed cells is abundant Cr-DNA adducts generated in the reactions of stable Cr(III) form with DNA phosphates. We have found that several Cr-DNA adducts were mutagenic during replication in human cells. Ternary DNA adducts containing bulky ligands, such as glutathione or ascorbate, induced the strongest mutagenic responses. We also determined that Cr(III)-dependent reactions were responsible for the formation of mutagenic DNA damage during reductive activation of Cr(VI) by its major biological reducers, cysteine and ascorbate. Additional data have shown that biological consequences of the formation of Cr(III)-DNA adducts are strongly influenced by the status of DNA mismatch repair system. We propose to elucidate the mechanisms of mismatch repair-dependent induction of stress signaling and formation of genetic alterations in Cr(VI)- exposed cells. Experiments will be performed to identify specific Cr-DNA adducts that are recognized by DNA mismatch repair and activate genotoxic responses. The results of this work should provide a greater understanding of molecular basis of Cr(VI) carcinogenesis, the importance of individual Cr-DNA adducts and uncover new functions of mismatch repair in recognition of DNA backbone modifications. Identification of the most potent genotoxic Cr-DNA adducts and critical pathways controlling cellular responses to Cr(VI) can be used in the development of useful biomarkers of exposure and individual susceptibility to adverse health effects."
1577076,Zhitkovich 2007,Sensitivity Mechanisms in Chromium Toxicity,"DESCRIPTION (provided by applicant): Hexavalent chromium (CrVI) is a toxic DNA-damaging agent with a well-documented exposure in a large number of occupations, and it is a common environmental contaminant. Cr(VI) is listed by the ATSDR and EPA as one of the top 20 high priority toxic agents. The final oxidative form of Cr in biological systems is Cr(lll) that produces several stable DNA adducts. We have recently found that Cr(III)-DNA adducts are one of the major causes of mutagenicity of Cr(VI). Our new data indicate that Cr-DNA adducts also play an important role in toxicity of Cr(VI). Toxic responses to Cr-DNA adducts were strongly dependent on the presence of a small group of proteins that bind to Cr-damaged chromatin. This proposal is designed to test our working hypothesis that cytotoxic effects of Cr-DNA adducts are caused by the formation of secondary DNA lesions generated as a result of the recognition and processing of adducts by damage sensory proteins. Biochemical approaches and cellular models with downregulated levels of damage-processing proteins will be used to gain evidence supporting the proposed hypothesis. We constructed a series of the retroviral siRNA-encoding vectors, which will allow us to examine the role of various proteins in the cytotoxic responses in the target primary human bronchial epithelial cells that have not been previously amenable to the mechanistic studies. The results of this work are expected to advance molecular understanding of Cr(VI) injury in the major target cells and to identify damage processing proteins that enhance toxicity of Cr-DNA modifications.","Sensitivity Mechanisms in Chromium Toxicity Abs: DESCRIPTION (provided by applicant): Hexavalent chromium (CrVI) is a toxic DNA-damaging agent with a well-documented exposure in a large number of occupations, and it is a common environmental contaminant. Cr(VI) is listed by the ATSDR and EPA as one of the top 20 high priority toxic agents. The final oxidative form of Cr in biological systems is Cr(lll) that produces several stable DNA adducts. We have recently found that Cr(III)-DNA adducts are one of the major causes of mutagenicity of Cr(VI). Our new data indicate that Cr-DNA adducts also play an important role in toxicity of Cr(VI). Toxic responses to Cr-DNA adducts were strongly dependent on the presence of a small group of proteins that bind to Cr-damaged chromatin. This proposal is designed to test our working hypothesis that cytotoxic effects of Cr-DNA adducts are caused by the formation of secondary DNA lesions generated as a result of the recognition and processing of adducts by damage sensory proteins. Biochemical approaches and cellular models with downregulated levels of damage-processing proteins will be used to gain evidence supporting the proposed hypothesis. We constructed a series of the retroviral siRNA-encoding vectors, which will allow us to examine the role of various proteins in the cytotoxic responses in the target primary human bronchial epithelial cells that have not been previously amenable to the mechanistic studies. The results of this work are expected to advance molecular understanding of Cr(VI) injury in the major target cells and to identify damage processing proteins that enhance toxicity of Cr-DNA modifications."
1577075,Zhitkovich 2007,Biological Dosimetry of Hexavalent Chromium,"Chromium and its compounds are major contaminants at a large number of the Superfund sites. Chromium exists in several oxidation states, among which only hexavalent form is associated with carcinogenic and other toxic effects of this metal. Superfund sites and other sources of environmental contamination usually contain chromium in different oxidation forms, which makes it difficult to assess human exposure to toxic chromium(VI) based on total levels of chromium in biological samples. We have previously determined that the most abundant form of DMA damage in chromium(VI)-exposed cells are mutagenic ternary chromium- DNA complexes containing ascorbate and amino acid/peptide ligands. In this work we propose to characterize the use of measurements of ternary adducts as a biomarker of genetic damage by chromium(VI) in human cells. Experiments will be performed to identify slowly repairable forms of chromium-DNA adducts, the role of biological repair and ligand exchange-dependent loss, the influence of co-exposure to other metals on biological characteristics of chromium-DNA adducts and to develop a more sensitive analytical methodology for the determination of major mutagenic chromium-DNA modifications.","Biological Dosimetry of Hexavalent Chromium Abs: Chromium and its compounds are major contaminants at a large number of the Superfund sites. Chromium exists in several oxidation states, among which only hexavalent form is associated with carcinogenic and other toxic effects of this metal. Superfund sites and other sources of environmental contamination usually contain chromium in different oxidation forms, which makes it difficult to assess human exposure to toxic chromium(VI) based on total levels of chromium in biological samples. We have previously determined that the most abundant form of DMA damage in chromium(VI)-exposed cells are mutagenic ternary chromium- DNA complexes containing ascorbate and amino acid/peptide ligands. In this work we propose to characterize the use of measurements of ternary adducts as a biomarker of genetic damage by chromium(VI) in human cells. Experiments will be performed to identify slowly repairable forms of chromium-DNA adducts, the role of biological repair and ligand exchange-dependent loss, the influence of co-exposure to other metals on biological characteristics of chromium-DNA adducts and to develop a more sensitive analytical methodology for the determination of major mutagenic chromium-DNA modifications."
1577074,Shi 2008,Oxidative Stress in Cr(VI)-induced Carcinogenesis,"DESCRIPTION (provided by applicant): Hexavalent chromium [Cr(VI)] is a known environmental carcinogen. Environmental exposure to Cr(VI)-containing compounds causes cancers of various organs. Its mechanism of carcinogenic actions remains to be investigated. Recent studies have demonstrated that reduction of Cr(VI) to its lower oxidation states is important for Cr(VI)-induced carcinogenesis. It has been shown that cellular reduction of Cr(VI) generates reactive oxygen species (ROS) which cause various cellular injuries. We hypothesize that Cr(VI) induces generation of ROS, which activate nuclear transcription factors, leading to cell transformation and tumorigenesis. In Specific Aim 1, we will identify ROS generated in Cr(VI) treated human lung bronchial epithelial (BEAS-2B) cells and the mechanism involved. We will emphysize the role of CDC42 signaling and the involvement of p47phox and NADPH oxidases in the molecular mechanism of Cr(VI)-induced ROS production. In Specific Aim 2, we will detect reactive Cr(V) intermediates produced in Cr(VI) reduction by living animals and identify the chemical structures of these intermediates. We will also detect and identify superoxide (O2'-) and hydroxyl ('OH) radicals produced by intact animals exposed to Cr(VI). Major methods to be used in this aim are low frequency electron spin resonance (ESR) spectroscopy and ESR spin trapping. In Specific Aim 3, we will investigate Cr(VI)-induced activation of NF-kappaB and AP-1 in BEAS-2B cells and in transgenic mice. We will use a dominant negative mutant MEK1/2, a dominant negative mutant ERK2, or a dominant negative mutant c-jun (TAM67), respectively, to investigate the role of the MEK1/2-ERKs-AP-1 pathway in Cr(VI)-induced cell transformation. We will also use a dominant negative mutant IkappaBa or a dominant negative mutant IKK?, respectively, to determine the role of the IKK?-lkappaBa-NF-kappaB pathway in Cr(VI)-induced cell transformation. The involvement of ROS in these pathways will be investigated using expressions of specific antioxidant enzymes. Tumorigenesis will be investigated by injecting the transformed cells into athymic nude mice. We anticipate that Cr(VI) causes activation of transcription factors through ROS reactions, leading to cell transformation and tumorigenesis. We attempt to link the cell transformation, and tumorigenesis with specific transcription factors and specific reactive oxygen species.","Oxidative Stress in Cr(VI)-induced Carcinogenesis Abs: DESCRIPTION (provided by applicant): Hexavalent chromium [Cr(VI)] is a known environmental carcinogen. Environmental exposure to Cr(VI)-containing compounds causes cancers of various organs. Its mechanism of carcinogenic actions remains to be investigated. Recent studies have demonstrated that reduction of Cr(VI) to its lower oxidation states is important for Cr(VI)-induced carcinogenesis. It has been shown that cellular reduction of Cr(VI) generates reactive oxygen species (ROS) which cause various cellular injuries. We hypothesize that Cr(VI) induces generation of ROS, which activate nuclear transcription factors, leading to cell transformation and tumorigenesis. In Specific Aim 1, we will identify ROS generated in Cr(VI) treated human lung bronchial epithelial (BEAS-2B) cells and the mechanism involved. We will emphysize the role of CDC42 signaling and the involvement of p47phox and NADPH oxidases in the molecular mechanism of Cr(VI)-induced ROS production. In Specific Aim 2, we will detect reactive Cr(V) intermediates produced in Cr(VI) reduction by living animals and identify the chemical structures of these intermediates. We will also detect and identify superoxide (O2'-) and hydroxyl ('OH) radicals produced by intact animals exposed to Cr(VI). Major methods to be used in this aim are low frequency electron spin resonance (ESR) spectroscopy and ESR spin trapping. In Specific Aim 3, we will investigate Cr(VI)-induced activation of NF-kappaB and AP-1 in BEAS-2B cells and in transgenic mice. We will use a dominant negative mutant MEK1/2, a dominant negative mutant ERK2, or a dominant negative mutant c-jun (TAM67), respectively, to investigate the role of the MEK1/2-ERKs-AP-1 pathway in Cr(VI)-induced cell transformation. We will also use a dominant negative mutant IkappaBa or a dominant negative mutant IKK?, respectively, to determine the role of the IKK?-lkappaBa-NF-kappaB pathway in Cr(VI)-induced cell transformation. The involvement of ROS in these pathways will be investigated using expressions of specific antioxidant enzymes. Tumorigenesis will be investigated by injecting the transformed cells into athymic nude mice. We anticipate that Cr(VI) causes activation of transcription factors through ROS reactions, leading to cell transformation and tumorigenesis. We attempt to link the cell transformation, and tumorigenesis with specific transcription factors and specific reactive oxygen species."
1577073,Zhitkovich 2008,Sensitivity Mechanisms in Chromium Toxicity,"DESCRIPTION (provided by applicant): Hexavalent chromium (CrVI) is a toxic DNA-damaging agent with a well-documented exposure in a large number of occupations, and it is a common environmental contaminant. Cr(VI) is listed by the ATSDR and EPA as one of the top 20 high priority toxic agents. The final oxidative form of Cr in biological systems is Cr(lll) that produces several stable DNA adducts. We have recently found that Cr(III)-DNA adducts are one of the major causes of mutagenicity of Cr(VI). Our new data indicate that Cr-DNA adducts also play an important role in toxicity of Cr(VI). Toxic responses to Cr-DNA adducts were strongly dependent on the presence of a small group of proteins that bind to Cr-damaged chromatin. This proposal is designed to test our working hypothesis that cytotoxic effects of Cr-DNA adducts are caused by the formation of secondary DNA lesions generated as a result of the recognition and processing of adducts by damage sensory proteins. Biochemical approaches and cellular models with downregulated levels of damage-processing proteins will be used to gain evidence supporting the proposed hypothesis. We constructed a series of the retroviral siRNA-encoding vectors, which will allow us to examine the role of various proteins in the cytotoxic responses in the target primary human bronchial epithelial cells that have not been previously amenable to the mechanistic studies. The results of this work are expected to advance molecular understanding of Cr(VI) injury in the major target cells and to identify damage processing proteins that enhance toxicity of Cr-DNA modifications.","Sensitivity Mechanisms in Chromium Toxicity Abs: DESCRIPTION (provided by applicant): Hexavalent chromium (CrVI) is a toxic DNA-damaging agent with a well-documented exposure in a large number of occupations, and it is a common environmental contaminant. Cr(VI) is listed by the ATSDR and EPA as one of the top 20 high priority toxic agents. The final oxidative form of Cr in biological systems is Cr(lll) that produces several stable DNA adducts. We have recently found that Cr(III)-DNA adducts are one of the major causes of mutagenicity of Cr(VI). Our new data indicate that Cr-DNA adducts also play an important role in toxicity of Cr(VI). Toxic responses to Cr-DNA adducts were strongly dependent on the presence of a small group of proteins that bind to Cr-damaged chromatin. This proposal is designed to test our working hypothesis that cytotoxic effects of Cr-DNA adducts are caused by the formation of secondary DNA lesions generated as a result of the recognition and processing of adducts by damage sensory proteins. Biochemical approaches and cellular models with downregulated levels of damage-processing proteins will be used to gain evidence supporting the proposed hypothesis. We constructed a series of the retroviral siRNA-encoding vectors, which will allow us to examine the role of various proteins in the cytotoxic responses in the target primary human bronchial epithelial cells that have not been previously amenable to the mechanistic studies. The results of this work are expected to advance molecular understanding of Cr(VI) injury in the major target cells and to identify damage processing proteins that enhance toxicity of Cr-DNA modifications."
1577072,Shi 2009,Oxidative Stress in Cr(VI)-induced Carcinogenesis,"DESCRIPTION (provided by applicant): Hexavalent chromium [Cr(VI)] is a known environmental carcinogen. Environmental exposure to Cr(VI)-containing compounds causes cancers of various organs. Its mechanism of carcinogenic actions remains to be investigated. Recent studies have demonstrated that reduction of Cr(VI) to its lower oxidation states is important for Cr(VI)-induced carcinogenesis. It has been shown that cellular reduction of Cr(VI) generates reactive oxygen species (ROS) which cause various cellular injuries. We hypothesize that Cr(VI) induces generation of ROS, which activate nuclear transcription factors, leading to cell transformation and tumorigenesis. In Specific Aim 1, we will identify ROS generated in Cr(VI) treated human lung bronchial epithelial (BEAS-2B) cells and the mechanism involved. We will emphysize the role of CDC42 signaling and the involvement of p47phox and NADPH oxidases in the molecular mechanism of Cr(VI)-induced ROS production. In Specific Aim 2, we will detect reactive Cr(V) intermediates produced in Cr(VI) reduction by living animals and identify the chemical structures of these intermediates. We will also detect and identify superoxide (O2'-) and hydroxyl ('OH) radicals produced by intact animals exposed to Cr(VI). Major methods to be used in this aim are low frequency electron spin resonance (ESR) spectroscopy and ESR spin trapping. In Specific Aim 3, we will investigate Cr(VI)-induced activation of NF-kappaB and AP-1 in BEAS-2B cells and in transgenic mice. We will use a dominant negative mutant MEK1/2, a dominant negative mutant ERK2, or a dominant negative mutant c-jun (TAM67), respectively, to investigate the role of the MEK1/2-ERKs-AP-1 pathway in Cr(VI)-induced cell transformation. We will also use a dominant negative mutant IkappaBa or a dominant negative mutant IKK?, respectively, to determine the role of the IKK?-lkappaBa-NF-kappaB pathway in Cr(VI)-induced cell transformation. The involvement of ROS in these pathways will be investigated using expressions of specific antioxidant enzymes. Tumorigenesis will be investigated by injecting the transformed cells into athymic nude mice. We anticipate that Cr(VI) causes activation of transcription factors through ROS reactions, leading to cell transformation and tumorigenesis. We attempt to link the cell transformation, and tumorigenesis with specific transcription factors and specific reactive oxygen species.","Oxidative Stress in Cr(VI)-induced Carcinogenesis Abs: DESCRIPTION (provided by applicant): Hexavalent chromium [Cr(VI)] is a known environmental carcinogen. Environmental exposure to Cr(VI)-containing compounds causes cancers of various organs. Its mechanism of carcinogenic actions remains to be investigated. Recent studies have demonstrated that reduction of Cr(VI) to its lower oxidation states is important for Cr(VI)-induced carcinogenesis. It has been shown that cellular reduction of Cr(VI) generates reactive oxygen species (ROS) which cause various cellular injuries. We hypothesize that Cr(VI) induces generation of ROS, which activate nuclear transcription factors, leading to cell transformation and tumorigenesis. In Specific Aim 1, we will identify ROS generated in Cr(VI) treated human lung bronchial epithelial (BEAS-2B) cells and the mechanism involved. We will emphysize the role of CDC42 signaling and the involvement of p47phox and NADPH oxidases in the molecular mechanism of Cr(VI)-induced ROS production. In Specific Aim 2, we will detect reactive Cr(V) intermediates produced in Cr(VI) reduction by living animals and identify the chemical structures of these intermediates. We will also detect and identify superoxide (O2'-) and hydroxyl ('OH) radicals produced by intact animals exposed to Cr(VI). Major methods to be used in this aim are low frequency electron spin resonance (ESR) spectroscopy and ESR spin trapping. In Specific Aim 3, we will investigate Cr(VI)-induced activation of NF-kappaB and AP-1 in BEAS-2B cells and in transgenic mice. We will use a dominant negative mutant MEK1/2, a dominant negative mutant ERK2, or a dominant negative mutant c-jun (TAM67), respectively, to investigate the role of the MEK1/2-ERKs-AP-1 pathway in Cr(VI)-induced cell transformation. We will also use a dominant negative mutant IkappaBa or a dominant negative mutant IKK?, respectively, to determine the role of the IKK?-lkappaBa-NF-kappaB pathway in Cr(VI)-induced cell transformation. The involvement of ROS in these pathways will be investigated using expressions of specific antioxidant enzymes. Tumorigenesis will be investigated by injecting the transformed cells into athymic nude mice. We anticipate that Cr(VI) causes activation of transcription factors through ROS reactions, leading to cell transformation and tumorigenesis. We attempt to link the cell transformation, and tumorigenesis with specific transcription factors and specific reactive oxygen species."
1577071,Shi 2010,Oxidative Stress in Cr(VI)-induced Carcinogenesis,"DESCRIPTION (provided by applicant): Hexavalent chromium [Cr(VI)] is a known environmental carcinogen. Environmental exposure to Cr(VI)-containing compounds causes cancers of various organs. Its mechanism of carcinogenic actions remains to be investigated. Recent studies have demonstrated that reduction of Cr(VI) to its lower oxidation states is important for Cr(VI)-induced carcinogenesis. It has been shown that cellular reduction of Cr(VI) generates reactive oxygen species (ROS) which cause various cellular injuries. We hypothesize that Cr(VI) induces generation of ROS, which activate nuclear transcription factors, leading to cell transformation and tumorigenesis. In Specific Aim 1, we will identify ROS generated in Cr(VI) treated human lung bronchial epithelial (BEAS-2B) cells and the mechanism involved. We will emphysize the role of CDC42 signaling and the involvement of p47phox and NADPH oxidases in the molecular mechanism of Cr(VI)-induced ROS production. In Specific Aim 2, we will detect reactive Cr(V) intermediates produced in Cr(VI) reduction by living animals and identify the chemical structures of these intermediates. We will also detect and identify superoxide (O2'-) and hydroxyl ('OH) radicals produced by intact animals exposed to Cr(VI). Major methods to be used in this aim are low frequency electron spin resonance (ESR) spectroscopy and ESR spin trapping. In Specific Aim 3, we will investigate Cr(VI)-induced activation of NF-kappaB and AP-1 in BEAS-2B cells and in transgenic mice. We will use a dominant negative mutant MEK1/2, a dominant negative mutant ERK2, or a dominant negative mutant c-jun (TAM67), respectively, to investigate the role of the MEK1/2-ERKs-AP-1 pathway in Cr(VI)-induced cell transformation. We will also use a dominant negative mutant IkappaBa or a dominant negative mutant IKK?, respectively, to determine the role of the IKK?-lkappaBa-NF-kappaB pathway in Cr(VI)-induced cell transformation. The involvement of ROS in these pathways will be investigated using expressions of specific antioxidant enzymes. Tumorigenesis will be investigated by injecting the transformed cells into athymic nude mice. We anticipate that Cr(VI) causes activation of transcription factors through ROS reactions, leading to cell transformation and tumorigenesis. We attempt to link the cell transformation, and tumorigenesis with specific transcription factors and specific reactive oxygen species.","Oxidative Stress in Cr(VI)-induced Carcinogenesis Abs: DESCRIPTION (provided by applicant): Hexavalent chromium [Cr(VI)] is a known environmental carcinogen. Environmental exposure to Cr(VI)-containing compounds causes cancers of various organs. Its mechanism of carcinogenic actions remains to be investigated. Recent studies have demonstrated that reduction of Cr(VI) to its lower oxidation states is important for Cr(VI)-induced carcinogenesis. It has been shown that cellular reduction of Cr(VI) generates reactive oxygen species (ROS) which cause various cellular injuries. We hypothesize that Cr(VI) induces generation of ROS, which activate nuclear transcription factors, leading to cell transformation and tumorigenesis. In Specific Aim 1, we will identify ROS generated in Cr(VI) treated human lung bronchial epithelial (BEAS-2B) cells and the mechanism involved. We will emphysize the role of CDC42 signaling and the involvement of p47phox and NADPH oxidases in the molecular mechanism of Cr(VI)-induced ROS production. In Specific Aim 2, we will detect reactive Cr(V) intermediates produced in Cr(VI) reduction by living animals and identify the chemical structures of these intermediates. We will also detect and identify superoxide (O2'-) and hydroxyl ('OH) radicals produced by intact animals exposed to Cr(VI). Major methods to be used in this aim are low frequency electron spin resonance (ESR) spectroscopy and ESR spin trapping. In Specific Aim 3, we will investigate Cr(VI)-induced activation of NF-kappaB and AP-1 in BEAS-2B cells and in transgenic mice. We will use a dominant negative mutant MEK1/2, a dominant negative mutant ERK2, or a dominant negative mutant c-jun (TAM67), respectively, to investigate the role of the MEK1/2-ERKs-AP-1 pathway in Cr(VI)-induced cell transformation. We will also use a dominant negative mutant IkappaBa or a dominant negative mutant IKK?, respectively, to determine the role of the IKK?-lkappaBa-NF-kappaB pathway in Cr(VI)-induced cell transformation. The involvement of ROS in these pathways will be investigated using expressions of specific antioxidant enzymes. Tumorigenesis will be investigated by injecting the transformed cells into athymic nude mice. We anticipate that Cr(VI) causes activation of transcription factors through ROS reactions, leading to cell transformation and tumorigenesis. We attempt to link the cell transformation, and tumorigenesis with specific transcription factors and specific reactive oxygen species."
1577070,Shi 2011,Oxidative Stress in Cr(VI)-induced Carcinogenesis,"DESCRIPTION (provided by applicant): Hexavalent chromium [Cr(VI)] is a known environmental carcinogen. Environmental exposure to Cr(VI)-containing compounds causes cancers of various organs. Its mechanism of carcinogenic actions remains to be investigated. Recent studies have demonstrated that reduction of Cr(VI) to its lower oxidation states is important for Cr(VI)-induced carcinogenesis. It has been shown that cellular reduction of Cr(VI) generates reactive oxygen species (ROS) which cause various cellular injuries. We hypothesize that Cr(VI) induces generation of ROS, which activate nuclear transcription factors, leading to cell transformation and tumorigenesis. In Specific Aim 1, we will identify ROS generated in Cr(VI) treated human lung bronchial epithelial (BEAS-2B) cells and the mechanism involved. We will emphysize the role of CDC42 signaling and the involvement of p47phox and NADPH oxidases in the molecular mechanism of Cr(VI)-induced ROS production. In Specific Aim 2, we will detect reactive Cr(V) intermediates produced in Cr(VI) reduction by living animals and identify the chemical structures of these intermediates. We will also detect and identify superoxide (O2'-) and hydroxyl ('OH) radicals produced by intact animals exposed to Cr(VI). Major methods to be used in this aim are low frequency electron spin resonance (ESR) spectroscopy and ESR spin trapping. In Specific Aim 3, we will investigate Cr(VI)-induced activation of NF-kappaB and AP-1 in BEAS-2B cells and in transgenic mice. We will use a dominant negative mutant MEK1/2, a dominant negative mutant ERK2, or a dominant negative mutant c-jun (TAM67), respectively, to investigate the role of the MEK1/2-ERKs-AP-1 pathway in Cr(VI)-induced cell transformation. We will also use a dominant negative mutant IkappaBa or a dominant negative mutant IKK?, respectively, to determine the role of the IKK?-lkappaBa-NF-kappaB pathway in Cr(VI)-induced cell transformation. The involvement of ROS in these pathways will be investigated using expressions of specific antioxidant enzymes. Tumorigenesis will be investigated by injecting the transformed cells into athymic nude mice. We anticipate that Cr(VI) causes activation of transcription factors through ROS reactions, leading to cell transformation and tumorigenesis. We attempt to link the cell transformation, and tumorigenesis with specific transcription factors and specific reactive oxygen species.","Oxidative Stress in Cr(VI)-induced Carcinogenesis Abs: DESCRIPTION (provided by applicant): Hexavalent chromium [Cr(VI)] is a known environmental carcinogen. Environmental exposure to Cr(VI)-containing compounds causes cancers of various organs. Its mechanism of carcinogenic actions remains to be investigated. Recent studies have demonstrated that reduction of Cr(VI) to its lower oxidation states is important for Cr(VI)-induced carcinogenesis. It has been shown that cellular reduction of Cr(VI) generates reactive oxygen species (ROS) which cause various cellular injuries. We hypothesize that Cr(VI) induces generation of ROS, which activate nuclear transcription factors, leading to cell transformation and tumorigenesis. In Specific Aim 1, we will identify ROS generated in Cr(VI) treated human lung bronchial epithelial (BEAS-2B) cells and the mechanism involved. We will emphysize the role of CDC42 signaling and the involvement of p47phox and NADPH oxidases in the molecular mechanism of Cr(VI)-induced ROS production. In Specific Aim 2, we will detect reactive Cr(V) intermediates produced in Cr(VI) reduction by living animals and identify the chemical structures of these intermediates. We will also detect and identify superoxide (O2'-) and hydroxyl ('OH) radicals produced by intact animals exposed to Cr(VI). Major methods to be used in this aim are low frequency electron spin resonance (ESR) spectroscopy and ESR spin trapping. In Specific Aim 3, we will investigate Cr(VI)-induced activation of NF-kappaB and AP-1 in BEAS-2B cells and in transgenic mice. We will use a dominant negative mutant MEK1/2, a dominant negative mutant ERK2, or a dominant negative mutant c-jun (TAM67), respectively, to investigate the role of the MEK1/2-ERKs-AP-1 pathway in Cr(VI)-induced cell transformation. We will also use a dominant negative mutant IkappaBa or a dominant negative mutant IKK?, respectively, to determine the role of the IKK?-lkappaBa-NF-kappaB pathway in Cr(VI)-induced cell transformation. The involvement of ROS in these pathways will be investigated using expressions of specific antioxidant enzymes. Tumorigenesis will be investigated by injecting the transformed cells into athymic nude mice. We anticipate that Cr(VI) causes activation of transcription factors through ROS reactions, leading to cell transformation and tumorigenesis. We attempt to link the cell transformation, and tumorigenesis with specific transcription factors and specific reactive oxygen species."
1577068,Xie et al. 2011,Aurora kinases play a critical role in hexavalent chromium-induced aneuploidy in immortalized human melanocytes,,Aurora kinases play a critical role in hexavalent chromium-induced aneuploidy in immortalized human melanocytes Abs: 
1577067,Xie et al. 2003,Lead chromate genotoxicity is mediated by particle dissolution and not particle internalization,,Lead chromate genotoxicity is mediated by particle dissolution and not particle internalization Abs: 
1577066,Wise et al. 2003,Chromium is the proximate genotoxic species in lead chromate-induced genotoxicity in human bronchial cells,,Chromium is the proximate genotoxic species in lead chromate-induced genotoxicity in human bronchial cells Abs: 
1577065,Wise et al. 2011,"The cytotoxicity and genotoxicity of hexavalent chromium in Steller sea lion lung fibroblasts compared to human lung fibroblasts (vol 152, pg 91, 2010)",,"The cytotoxicity and genotoxicity of hexavalent chromium in Steller sea lion lung fibroblasts compared to human lung fibroblasts (vol 152, pg 91, 2010) Abs: "
1577064,Wang et al. 2011,"Hexavalent Chromium-induced ROS Formation, Subsequent Akt, NF-kappa B, and MAPK Activation, and TNF-alpha, and IL-1 alpha Production in Keratinocytes, Which Might Facilitate the Progression of Chromium Hypersensitivity",,"Hexavalent Chromium-induced ROS Formation, Subsequent Akt, NF-kappa B, and MAPK Activation, and TNF-alpha, and IL-1 alpha Production in Keratinocytes, Which Might Facilitate the Progression of Chromium Hypersensitivity Abs: "
1577063,Val et al. 2012,Senescent bronchial fibroblasts drive bronchial epithelial cells metaplasic transformation following exposure to hexavalent chromium,,Senescent bronchial fibroblasts drive bronchial epithelial cells metaplasic transformation following exposure to hexavalent chromium Abs: 
1577062,Thompson et al. 2012,Duodenal GSH/GSSG ratios in mice following oral exposure to Cr(VI),,Duodenal GSH/GSSG ratios in mice following oral exposure to Cr(VI) Abs: 
1577061,Sultan and  Hasnain 2009,Biological chromium (VI) reduction by chromium-resistant Ochrobactrum anthropi isolated from tannery effluent,,Biological chromium (VI) reduction by chromium-resistant Ochrobactrum anthropi isolated from tannery effluent Abs: 
1577060,Stoner et al. 1988,ACUTE CHROMIUM INTOXICATION WITH RENAL-FAILURE AFTER 1-PERCENT BODY-SURFACE AREA BURNS FROM CHROMIC-ACID,,ACUTE CHROMIUM INTOXICATION WITH RENAL-FAILURE AFTER 1-PERCENT BODY-SURFACE AREA BURNS FROM CHROMIC-ACID Abs: 
1577059,Stern 2011,Reply to Proctor et al,,Reply to Proctor et al Abs: 
1577058,Stanley et al. 2011,Hexavalent Chromium Through Lactational Exposure Delayed Follicular Development in Pre-Pubertal F1 Offspring: Mechanistic Insights into Cell Cycle Regulation of Granulosa Cells,,Hexavalent Chromium Through Lactational Exposure Delayed Follicular Development in Pre-Pubertal F1 Offspring: Mechanistic Insights into Cell Cycle Regulation of Granulosa Cells Abs: 
1577057,Soares et al. 2009,Hexavalent chromium as a contaminant of food matrices: Its control in bread samples,,Hexavalent chromium as a contaminant of food matrices: Its control in bread samples Abs: 
1577056,Smith 2009,On the Chromium Reanalysis Response,,On the Chromium Reanalysis Response Abs: 
1577055,Shi and  Ye 1999,Role of reavtive oxygen species and p53 in chromium(VI)-induced apoptosis,,Role of reavtive oxygen species and p53 in chromium(VI)-induced apoptosis Abs: 
1577054,Sedman and  Howd 2003,Risk assessment for hexavalent chromium in drinking water,,Risk assessment for hexavalent chromium in drinking water Abs: 
1577053,Scout 2006,The case of chromium(VI) - Reply,,The case of chromium(VI) - Reply Abs: 
1577052,Schmitt and  Krusejarres 1988,SEPARATION OF CHROMIUM(III) FROM CHROMIUM(VI) USING GRAPHITE-FURNACE CHEMISTRY,,SEPARATION OF CHROMIUM(III) FROM CHROMIUM(VI) USING GRAPHITE-FURNACE CHEMISTRY Abs: 
1577050,Sabatino et al. 1978,ACUTE EFFECTS OF SODIUM MALEATE AND SODIUM CHROMATE ON URINARY PROTEIN EXCRETION IN THE RAT,,ACUTE EFFECTS OF SODIUM MALEATE AND SODIUM CHROMATE ON URINARY PROTEIN EXCRETION IN THE RAT Abs: 
1577049,Rudolf et al. 2008,Hexavalent chromium induces DNA damage and activates DNA-damage-response pathway in human skin cells,,Hexavalent chromium induces DNA damage and activates DNA-damage-response pathway in human skin cells Abs: 
1577048,Rodrigues et al. 2009,Hexavalent chromium and lung cancer: new perspectives,,Hexavalent chromium and lung cancer: new perspectives Abs: 
1577047,Rodrigues et al. 2008,Clastogenic effects of hexavalent chromium in a human bronchial epithelial cell line,,Clastogenic effects of hexavalent chromium in a human bronchial epithelial cell line Abs: 
1577046,Raghunathan et al. 2008,Uptake of Cr (VI) and Cr (III)-GSH complex across rat liver cell nuclei,,Uptake of Cr (VI) and Cr (III)-GSH complex across rat liver cell nuclei Abs: 
1577045,Raghunathan et al. 2007,Involvement of reduced glutathione and glutathione reductase in the chronic toxicity of hexavalent chromium to monocytes in vitro,,Involvement of reduced glutathione and glutathione reductase in the chronic toxicity of hexavalent chromium to monocytes in vitro Abs: 
1577044,Proctor and  Ohanian 2003,"Health risk assessment of hexavalent chromium in drinking water: Carcinogenicity, research, and regulation",,"Health risk assessment of hexavalent chromium in drinking water: Carcinogenicity, research, and regulation Abs: "
1577043,Proctor et al. 2002,Alternative reference population sensitivity analysis for the mortality assessment of a hexavalent chromium exposed worker cohort,,Alternative reference population sensitivity analysis for the mortality assessment of a hexavalent chromium exposed worker cohort Abs: 
1577042,Pikaev et al. 1974,DETERMINATION OF HYDROGEN-ION YIELD AT PULSE-RADIOLYSIS OF AQUEOUS-SOLUTIONS OF POTASSIUM CHROMATE,,DETERMINATION OF HYDROGEN-ION YIELD AT PULSE-RADIOLYSIS OF AQUEOUS-SOLUTIONS OF POTASSIUM CHROMATE Abs: 
1577041,Paustenbach et al. 2006,Factors affecting the bioaccessibility and bioavailability of hexavalent chromium and dioxin contaminants in soil and their relevance to risk assessment,,Factors affecting the bioaccessibility and bioavailability of hexavalent chromium and dioxin contaminants in soil and their relevance to risk assessment Abs: 
1577039,Patlolla and  Tchounwou 2006,Cytogenetic evaluation of potassium dichromate toxicity in bone-marrow cells of Sprague-Dawley rats,,Cytogenetic evaluation of potassium dichromate toxicity in bone-marrow cells of Sprague-Dawley rats Abs: 
1577037,Paschin et al. 1982,CYTOGENETIC STUDIES AND DOMINANT LETHAL TEST WITH LOW-DOSES OF POTASSIUM DICHROMATE IN MICE,,CYTOGENETIC STUDIES AND DOMINANT LETHAL TEST WITH LOW-DOSES OF POTASSIUM DICHROMATE IN MICE Abs: 
1577036,Park and  Stayner 2005,Search for thresholds and other nonlinearities in the hexavalent chromium - Lung cancer exposure response,,Search for thresholds and other nonlinearities in the hexavalent chromium - Lung cancer exposure response Abs: 
1577035,Pan et al. 2009,Effects of Exposure to Hexavalent Chromium on Male Electroplating Workers,,Effects of Exposure to Hexavalent Chromium on Male Electroplating Workers Abs: 
1577034,O'Hara et al. 2004,Chromium (VI) inhibits heme oxygenase-1 induction in both cell and in vivo models,,Chromium (VI) inhibits heme oxygenase-1 induction in both cell and in vivo models Abs: 
1577033,O'Hara et al. 2003,Mechanisms for selective activation of SRC family kinases and JNK by low levels of chromium(VI),,Mechanisms for selective activation of SRC family kinases and JNK by low levels of chromium(VI) Abs: 
1577032,O'Hara et al. 2002,Mechanisms for selective activation of SRC family kinases and JNK by low levels of chromium(VI),,Mechanisms for selective activation of SRC family kinases and JNK by low levels of chromium(VI) Abs: 
1577031,O'Hara et al. 2001,Selective JNK activation by low level chromium(VI) requires oxidants and Src family kinases,,Selective JNK activation by low level chromium(VI) requires oxidants and Src family kinases Abs: 
1577030,O'Hara et al. 2003,Chromium(VI)-induced pulmonary signaling and proliferation in vivo,,Chromium(VI)-induced pulmonary signaling and proliferation in vivo Abs: 
1577029,Ning and  Grant 2000,"Chromium (VI)-induced cytotoxicity to osteoblast-derived cells (vol 13, pg 879, 2000)",,"Chromium (VI)-induced cytotoxicity to osteoblast-derived cells (vol 13, pg 879, 2000) Abs: "
1577027,Nemery et al. 1993,"PULMONARY RESPONSE AFTER INTRATRACHEAL CHALLENGE WITH POTASSIUM DICHROMATE IN HAMSTERS, PREVIOUSLY SENSITIZED TO THIS METAL SALT BY DERMAL APPLICATION",,"PULMONARY RESPONSE AFTER INTRATRACHEAL CHALLENGE WITH POTASSIUM DICHROMATE IN HAMSTERS, PREVIOUSLY SENSITIZED TO THIS METAL SALT BY DERMAL APPLICATION Abs: "
1577026,Myers et al. 2008,The Effects of Hexavalent Chromium on Thioredoxin Reductase and Peroxiredoxins in Human Bronchial Epithelial Cells,,The Effects of Hexavalent Chromium on Thioredoxin Reductase and Peroxiredoxins in Human Bronchial Epithelial Cells Abs: 
1577025,Myers and  Myers 2007,Oxidation of thioredoxin in human bronchial epithelial cells exposed to hexavalent chromium,,Oxidation of thioredoxin in human bronchial epithelial cells exposed to hexavalent chromium Abs: 
1577024,Myers et al. 2006,BEAS-2B cells as a model for the reductive activation of hexavalent chromium in human lung epithelial cells,,BEAS-2B cells as a model for the reductive activation of hexavalent chromium in human lung epithelial cells Abs: 
1577023,Myers et al. 2010,The Pro-Oxidant Chromium(VI) Inhibits Multiple Core Mitochondrial Functions: EPR Markers for Multiple Iron-Sulfur Proteins,,The Pro-Oxidant Chromium(VI) Inhibits Multiple Core Mitochondrial Functions: EPR Markers for Multiple Iron-Sulfur Proteins Abs: 
1577022,Mundt et al. 2005,Hexavalent chromium study's conclusions unjustified - Reply,,Hexavalent chromium study's conclusions unjustified - Reply Abs: 
1577021,Mortuza et al. 2006,"Toxicity and bioaccumulation of hexavalent chromium in green paramecium, Paramecium bursaria (vol 51, pg 676, 2005)",,"Toxicity and bioaccumulation of hexavalent chromium in green paramecium, Paramecium bursaria (vol 51, pg 676, 2005) Abs: "
1577020,Moreland et al. 2003,The phase of lead chromate induced cell cycle arrest is concentration dependent,,The phase of lead chromate induced cell cycle arrest is concentration dependent Abs: 
1577019,Mattagajasingh and  Misra 1995,DETECTION OF CHROMIUM(VI)-INDUCED DNA-PROTEIN COMPLEXES IN HUMAN LEUKEMIC T-LYMPHOCYTE MOLT4 CELLS BY IMMUNOBLOTTING,,DETECTION OF CHROMIUM(VI)-INDUCED DNA-PROTEIN COMPLEXES IN HUMAN LEUKEMIC T-LYMPHOCYTE MOLT4 CELLS BY IMMUNOBLOTTING Abs: 
1576995,Mattagajasingh and  Misra 1994,INCREASED PRODUCTION OF OXIDANTS IN CULTURED HUMAN LEUKEMIC T-LYMPHOCYTE MOLT-4 CELLS TREATED WITH CHROMIUM(VI),,INCREASED PRODUCTION OF OXIDANTS IN CULTURED HUMAN LEUKEMIC T-LYMPHOCYTE MOLT-4 CELLS TREATED WITH CHROMIUM(VI) Abs: 
1576994,Mattagajasingh and  Misra 1993,VITAMIN-E SUPPRESSES THE POTASSIUM CHROMATE INDUCED CROSS-LINKING OF PROTEINS TO DNA IN MOLT-4 CELLS,,VITAMIN-E SUPPRESSES THE POTASSIUM CHROMATE INDUCED CROSS-LINKING OF PROTEINS TO DNA IN MOLT-4 CELLS Abs: 
1576993,Levina et al. 2003,Reactive intermediates formed during the reactions of chromium(VI) with glutathione: Which species are responsible for the DNA damage?,,Reactive intermediates formed during the reactions of chromium(VI) with glutathione: Which species are responsible for the DNA damage? Abs: 
1576992,Lee et al. 2004,Induction of apoptosis by chromium(VI) in lymphocytes from Sprage VDawley rats,,Induction of apoptosis by chromium(VI) in lymphocytes from Sprage VDawley rats Abs: 
1576991,Lalaouni et al. 2003,The interaction of hexavalent chromium with mouse macrophages,,The interaction of hexavalent chromium with mouse macrophages Abs: 
1576990,Krumschnabel and  Nawaz 2005,"Acute toxicity of hexavalent chromium in isolated teleost hepatocytes (vol 70, pg 159, 2004)",,"Acute toxicity of hexavalent chromium in isolated teleost hepatocytes (vol 70, pg 159, 2004) Abs: "
1576989,Komarov 2007,"Commentary on ""Reduction of hexavalent chromium by human cytochrome b(5): Generation of hydroxyl radical and superoxide,"" by G.R. Borthiry, W.E. Antholine, B. Kalyanaraman, J.M. Myers, C.R. Myers",,"Commentary on ""Reduction of hexavalent chromium by human cytochrome b(5): Generation of hydroxyl radical and superoxide,"" by G.R. Borthiry, W.E. Antholine, B. Kalyanaraman, J.M. Myers, C.R. Myers Abs: "
1576987,Kirpnick and  Schiestl 2003,Effects of extracellular and intracellular factors on chromium (III) and chromium (VI) genotoxicity,,Effects of extracellular and intracellular factors on chromium (III) and chromium (VI) genotoxicity Abs: 
1576986,Kimura et al. 2010,Chromium(VI) inhibits mouse metallothionein-I gene transcription by modifying transactivation potential of the co-activator p300,,Chromium(VI) inhibits mouse metallothionein-I gene transcription by modifying transactivation potential of the co-activator p300 Abs: 
1576985,Kim and  Kim 1998,"Effects of hexavalent chromium on 8-OH-DG, SOD and 8-hydroxyguanine endonuclease in rat lung",,"Effects of hexavalent chromium on 8-OH-DG, SOD and 8-hydroxyguanine endonuclease in rat lung Abs: "
1576984,Kennedy et al. 1976,TOXICITY OF LEAD CHROMATE PIGMENTS AND TISSUE RESIDUES FOLLOWING 90 DAYS FEEDING TO ALBINO-RATS,,TOXICITY OF LEAD CHROMATE PIGMENTS AND TISSUE RESIDUES FOLLOWING 90 DAYS FEEDING TO ALBINO-RATS Abs: 
1576983,Jamil et al. 1987,SENSITIZATION OF GUINEA-PIGS TO TRIVALENT AND HEXAVALENT CHROMIUM COMPOUNDS,,SENSITIZATION OF GUINEA-PIGS TO TRIVALENT AND HEXAVALENT CHROMIUM COMPOUNDS Abs: 
1576982,Huang et al. 2008,Optimization and Evaluation of a Sampling and Analytic Method for the Measurement of Hexavalent Chromium in Ambient Air,,Optimization and Evaluation of a Sampling and Analytic Method for the Measurement of Hexavalent Chromium in Ambient Air Abs: 
1576981,Holmes et al. 2003,Comparative genotoxicity of two particulate hexavalent chromium compounds in human bronchial cells,,Comparative genotoxicity of two particulate hexavalent chromium compounds in human bronchial cells Abs: 
1576980,Hodkova et al. 2010,The effect of chromium (VI) on the redox homeostasis and the activity of selenoenzymes thioredoxin reductase and glutathione peroxidase in rat liver and kidneys,,The effect of chromium (VI) on the redox homeostasis and the activity of selenoenzymes thioredoxin reductase and glutathione peroxidase in rat liver and kidneys Abs: 
1576979,Hodges and  Chipman 2001,Hexavalent chromium inhibits expression of the DNA-repair endonuclease 8-oxo-DNA glycosylase 1 (hOGG1) in cultured human A549 lung epithelial cells,,Hexavalent chromium inhibits expression of the DNA-repair endonuclease 8-oxo-DNA glycosylase 1 (hOGG1) in cultured human A549 lung epithelial cells Abs: 
1576978,Helsper and  Groot 1976,REACTION OF PHOSPHOTUNGSTIC ACID-CHROMIC ACID ON PLASMA-MEMBRANES AND GOLGI VESICLES IN POLLEN-TUBE TIPS OF PETUNIA HYBRIDA,,REACTION OF PHOSPHOTUNGSTIC ACID-CHROMIC ACID ON PLASMA-MEMBRANES AND GOLGI VESICLES IN POLLEN-TUBE TIPS OF PETUNIA HYBRIDA Abs: 
1576977,He et al. 2007,Protection against Chromium (VI)-induced oxidative stress and apoptosis by Nrf2. recruiting Nrf2 into the nucleus and disrupting the nuclear Nrf2/Keap1 association by toxic metal,,Protection against Chromium (VI)-induced oxidative stress and apoptosis by Nrf2. recruiting Nrf2 into the nucleus and disrupting the nuclear Nrf2/Keap1 association by toxic metal Abs: 
1576975,Hamilton 2003,Mechanism of hexavalent chromium [(CR(VI)] toxicity and carcinogenicity,,Mechanism of hexavalent chromium [(CR(VI)] toxicity and carcinogenicity Abs: 
1576974,Gorman et al. 1986,INGESTION OF AMMONIUM DICHROMATE,,INGESTION OF AMMONIUM DICHROMATE Abs: 
1576973,Goncalves et al. 2010,Changes in the energy status and glucose uptake rate of PC-12 cells induced by acute subcytotoxic or mildly cytotoxic hexavalent chromium insults,,Changes in the energy status and glucose uptake rate of PC-12 cells induced by acute subcytotoxic or mildly cytotoxic hexavalent chromium insults Abs: 
1576972,Gherardi et al. 2011,Environmental and biological monitoring for measuring the efficacy of personal protection equipments in the use of hexavalent chromium based paints,,Environmental and biological monitoring for measuring the efficacy of personal protection equipments in the use of hexavalent chromium based paints Abs: 
1576971,Gatto et al. 2007,Meta-analysis of occupational exposure to hexavalent chromium and stomach cancer,,Meta-analysis of occupational exposure to hexavalent chromium and stomach cancer Abs: 
1576970,Garcia-Rodriguez and  Altamirano-Lozano 2006,Study of effects of chlorophyllin on genotoxic and tetartogenic damage induced by chromium (VI),,Study of effects of chlorophyllin on genotoxic and tetartogenic damage induced by chromium (VI) Abs: 
1576969,Galvin et al. 1982,COMPARISON OF TOXICOLOGICAL MODELS FOR EVALUATION OF AIR-POLLUTANTS - RESPONSE OF THE PULMONARY ALVEOLAR MACROPHAGE TO HEXAVALENT CHROMIUM,,COMPARISON OF TOXICOLOGICAL MODELS FOR EVALUATION OF AIR-POLLUTANTS - RESPONSE OF THE PULMONARY ALVEOLAR MACROPHAGE TO HEXAVALENT CHROMIUM Abs: 
1576967,Frazer 2006,Hexavalent chromium exposure,,Hexavalent chromium exposure Abs: 
1576965,Fitzgerald and  Brooks 1979,NEW CELL FOR INVITRO SKIN PERMEABILITY STUDIES - CHROMIUM(III)-(VI) HUMAN-EPIDERMIS INVESTIGATIONS,,NEW CELL FOR INVITRO SKIN PERMEABILITY STUDIES - CHROMIUM(III)-(VI) HUMAN-EPIDERMIS INVESTIGATIONS Abs: 
1576963,Finley et al. 1993,COMPARATIVE EFFECTS OF TRIVALENT AND HEXAVALENT CHROMIUM ON SPERMATOGENESIS OF THE MOUSE - COMMENT,,COMPARATIVE EFFECTS OF TRIVALENT AND HEXAVALENT CHROMIUM ON SPERMATOGENESIS OF THE MOUSE - COMMENT Abs: 
1576961,Figueiredo et al. 2007,Transference of total chromium and hexavalent chromium from soils to mushrooms,,Transference of total chromium and hexavalent chromium from soils to mushrooms Abs: 
1576959,Farmer and  Jarvis 2009,"Strategies for improving human health in contaminated situations: a review of past, present and possible future approaches",,"Strategies for improving human health in contaminated situations: a review of past, present and possible future approaches Abs: "
1576957,Fan et al. 2008,"Spatial and Temporal Variation of Ambient Hexavalent Chromium in Urban Communities in Paterson, New Jersey",,"Spatial and Temporal Variation of Ambient Hexavalent Chromium in Urban Communities in Paterson, New Jersey Abs: "
1576948,Di Giacinto et al. 2010,"Early warning detection of hexavalent chromium in water by ""Daphnia Toximeter""",,"Early warning detection of hexavalent chromium in water by ""Daphnia Toximeter"" Abs: "
1576947,Das 2009,EEFFECT OF GARLIC (ALLIUM SATIVUM) ON NICKEL II AND CHROMIUM VI TOXICITIES IN NORMAL AND ALLOXAN INDUCED DIABETIC RATS,,EEFFECT OF GARLIC (ALLIUM SATIVUM) ON NICKEL II AND CHROMIUM VI TOXICITIES IN NORMAL AND ALLOXAN INDUCED DIABETIC RATS Abs: 
1576946,Cristiani-Urbina et al. 2009,Characterization of Cr(VI) reduction and chromium biosorption by Prunus domestica bark,,Characterization of Cr(VI) reduction and chromium biosorption by Prunus domestica bark Abs: 
1576945,Cooney and  Mujais 1985,RENAL NA-K-ATPASE IN POTASSIUM DICHROMATE INDUCED ACUTE RENAL-FAILURE IN THE RAT,,RENAL NA-K-ATPASE IN POTASSIUM DICHROMATE INDUCED ACUTE RENAL-FAILURE IN THE RAT Abs: 
1576944,Collins et al. 2011,"Hexavalent Chromium in Drinking Water, Reply",,"Hexavalent Chromium in Drinking Water, Reply Abs: "
1576942,Cavallo et al. 2010,EVALUATION OF DIRECT-OXIDATIVE DNA DAMAGE IN LUNG AND BRONCHIAL HUMAN CELLS EXPOSED TO LOW DOSES OF HEXAVALENT CHROMIUM,,EVALUATION OF DIRECT-OXIDATIVE DNA DAMAGE IN LUNG AND BRONCHIAL HUMAN CELLS EXPOSED TO LOW DOSES OF HEXAVALENT CHROMIUM Abs: 
1576941,Cavallo et al. 2008,Evaluation of genotoxic and oxidative effects on human bronchial cells exposed to low doses of hexavalent chromium,,Evaluation of genotoxic and oxidative effects on human bronchial cells exposed to low doses of hexavalent chromium Abs: 
1576940,Carlisle et al. 1999,Apoptosis induced by hexavalent chromium is p53 dependent,,Apoptosis induced by hexavalent chromium is p53 dependent Abs: 
1576911,Cantoni and  Costa 1983,CHARACTERIZATION AND MECHANISM OF DNA DAMAGE INDUCED BY CHROMIUM(VI) AND MERCURY(II) IN CULTURED MAMMALIAN-CELLS,,CHARACTERIZATION AND MECHANISM OF DNA DAMAGE INDUCED BY CHROMIUM(VI) AND MERCURY(II) IN CULTURED MAMMALIAN-CELLS Abs: 
1576910,Canesi et al. 2010,Effects of hexavalent chromium in Mytilus galloprovincialis,,Effects of hexavalent chromium in Mytilus galloprovincialis Abs: 
1576909,Campbell et al. 2011,The Developmental Toxicity of Hexavalent Chromium: A Review,,The Developmental Toxicity of Hexavalent Chromium: A Review Abs: 
1576908,Bucher and  Abdo 2003,National toxicology program studies of hexavalent chromium,,National toxicology program studies of hexavalent chromium Abs: 
1576907,Brambilla et al. 1980,DNA CROSSLINKING IN MAMMALIAN-CELLS TREATED WITH POTASSIUM DICHROMATE,,DNA CROSSLINKING IN MAMMALIAN-CELLS TREATED WITH POTASSIUM DICHROMATE Abs: 
1576906,Borthiry et al. 2006,Chromium(VI) reduction by human cytochrome B-5 generates hydroxyl radical and superoxide,,Chromium(VI) reduction by human cytochrome B-5 generates hydroxyl radical and superoxide Abs: 
1576905,Beveridge et al. 2008,"Risk of lung cancer after occupational exposure to cadmium, chromium VI, and nickel",,"Risk of lung cancer after occupational exposure to cadmium, chromium VI, and nickel Abs: "
1576904,Bernard and  Lauwerys 1980,THE EFFECTS OF SODIUM CHROMATE AND CARBON-TETRACHLORIDE ON THE URINARY-EXCRETION OF CADMIUM IN CADMIUM-PRETREATED RATS,,THE EFFECTS OF SODIUM CHROMATE AND CARBON-TETRACHLORIDE ON THE URINARY-EXCRETION OF CADMIUM IN CADMIUM-PRETREATED RATS Abs: 
1576903,Ben Rhouma et al. 2009,EMBRYO-TOXICITY AND FETO-TOXICITY FOLLOWING INTRAPERITONEAL ADMINISTRATIONS OF HEXAVALENT CHROMIUM TO PREGNANT RATS,,EMBRYO-TOXICITY AND FETO-TOXICITY FOLLOWING INTRAPERITONEAL ADMINISTRATIONS OF HEXAVALENT CHROMIUM TO PREGNANT RATS Abs: 
1576902,Beaumont et al. 2009,Chromium(VI) Ingestion and Cancer Response,,Chromium(VI) Ingestion and Cancer Response Abs: 
1576901,Beaumont et al. 2006,Analysis of cancer mortality data from five villages in China with hexavalent chromium-contaminated drinking water,,Analysis of cancer mortality data from five villages in China with hexavalent chromium-contaminated drinking water Abs: 
1576900,Banu et al. 2010,Gestational Exposure to Chromium (VI) Impairs Pregnancy Outcome and Fetal Development,,Gestational Exposure to Chromium (VI) Impairs Pregnancy Outcome and Fetal Development Abs: 
1576899,Banner et al. 1982,COAGULOPATHY FOLLOWING INGESTION OF POTASSIUM DICHROMATE,,COAGULOPATHY FOLLOWING INGESTION OF POTASSIUM DICHROMATE Abs: 
1576898,Bajraktari et al. 2006,Chromium(VI) oxide-CrO3 - Treatment causes eyeless (ey) and small eye (sey) individuals of D. melanogaster,,Chromium(VI) oxide-CrO3 - Treatment causes eyeless (ey) and small eye (sey) individuals of D. melanogaster Abs: 
1576897,Bajraktari et al. 2006,The effect of chromium(VI) oxide-CrO3 - On the duration of Drosophila melanogaster preadult development,,The effect of chromium(VI) oxide-CrO3 - On the duration of Drosophila melanogaster preadult development Abs: 
1576896,Altawil et al. 1982,LYMPHOCYTE STIMULATION BY TRIVALENT AND HEXAVALENT CHROMIUM COMPOUNDS IN PATIENTS WITH CHROMIUM SENSITIVITY,,LYMPHOCYTE STIMULATION BY TRIVALENT AND HEXAVALENT CHROMIUM COMPOUNDS IN PATIENTS WITH CHROMIUM SENSITIVITY Abs: 
1576895,Acosta et al. 2004,Differential histopathological response to oral administration of potassium dichromate (K2Cr2O7) between the wood mouse (Apodemus sylvaticus) and the laboratory mouse (Mus musculus),,Differential histopathological response to oral administration of potassium dichromate (K2Cr2O7) between the wood mouse (Apodemus sylvaticus) and the laboratory mouse (Mus musculus) Abs: 
1576894,Aoyama 2003,Comment on &quot;Biosorption of chromium(VI) from aqueous solution by cone biomass of Pinus sylvestris&quot,,Comment on &quot;Biosorption of chromium(VI) from aqueous solution by cone biomass of Pinus sylvestris&quot Abs: 
1576893,Yuan et al. 1999,[The utilization of mouse limb bud culture for evaluating the developmental toxicity of potassium dichromate in vitro],"Forelimb buds from 12th day mouse embryos were dissected and cultured in 0.5, 1.0, 2.0 and 4.0 mg K2Cr2O7/L MEM + 10% rat serum cultured for 6 days. The mouse forelimb development of the 0.5 and 1.0 mg/L groups were not significantly different from the controls whereas the higher concentrations resulted in a concentration related deterioration in limb development and differentiation. The results indicated that potassium dichromate can inhibit mouse limb bud development and differentiation in vitro. It is a potential developmental toxic substance in mice.","[The utilization of mouse limb bud culture for evaluating the developmental toxicity of potassium dichromate in vitro] Abs: Forelimb buds from 12th day mouse embryos were dissected and cultured in 0.5, 1.0, 2.0 and 4.0 mg K2Cr2O7/L MEM + 10% rat serum cultured for 6 days. The mouse forelimb development of the 0.5 and 1.0 mg/L groups were not significantly different from the controls whereas the higher concentrations resulted in a concentration related deterioration in limb development and differentiation. The results indicated that potassium dichromate can inhibit mouse limb bud development and differentiation in vitro. It is a potential developmental toxic substance in mice."
1576892,Lei and  Xing 1993,[The genotoxicity of air particles tested by SOS chromotest],"Samples of variously-sized total suspended particles in the air of one sampling site of TaiYuan city were collected. The samples were extracted with acid and a simulated lung fluid (SLF) respectively. Both extracts mainly consisted of metallic elements. Using SOS chromotest as a means to test the gentoxity of the extracts and five metallic compounds, namely Cr6+, Ni2+, Pb2+, Mn2+ and Cd2+ were tested first. All the compounds tested could induce the SOS response to various extent, showing that the method was sensitive to metallic compounds. For the extracts of air particles, both the extracts of acid and of SLF of the smaller-sized particles could induce SOS response. This indicated the existence of metaklic genotoxicants in the smaller-sized particles. Being convenient to use fast and precise, the SOS Chromotest has its unique advantage for detecting carcinogenic metallic compounds. TAX - ESCHERICHIA COLI,PQ37","[The genotoxicity of air particles tested by SOS chromotest] Abs: Samples of variously-sized total suspended particles in the air of one sampling site of TaiYuan city were collected. The samples were extracted with acid and a simulated lung fluid (SLF) respectively. Both extracts mainly consisted of metallic elements. Using SOS chromotest as a means to test the gentoxity of the extracts and five metallic compounds, namely Cr6+, Ni2+, Pb2+, Mn2+ and Cd2+ were tested first. All the compounds tested could induce the SOS response to various extent, showing that the method was sensitive to metallic compounds. For the extracts of air particles, both the extracts of acid and of SLF of the smaller-sized particles could induce SOS response. This indicated the existence of metaklic genotoxicants in the smaller-sized particles. Being convenient to use fast and precise, the SOS Chromotest has its unique advantage for detecting carcinogenic metallic compounds. TAX - ESCHERICHIA COLI,PQ37"
1576889,Zhang et al. 2005,[Highly sensitive spectrofluorimetric determination of trace amounts of chromium (VI) with mono[6-o-(4-aminobenzoic acid)]-beta-cyclodextrin],"A novel fluorescence probe, mono[6-o-(4-aminobenzoic acid)]-beta-cyclodextrin(ACD), was synthesized, and a new sensitive fluorescence identification reaction was studied based on the reaction of Cr2O7(2-) with compound ACD in NaAc-HAc buffer medium at pH 4.90. Under optimal conditions the determination limit was 1.26 microg x L(-1). The linear range was 5.20-1040 microg x L(-1). This method has been applied to the determination of trace amounts of chromium (VI) in electroplating liquor, electroplating waste water with satisfactory results.","[Highly sensitive spectrofluorimetric determination of trace amounts of chromium (VI) with mono[6-o-(4-aminobenzoic acid)]-beta-cyclodextrin] Abs: A novel fluorescence probe, mono[6-o-(4-aminobenzoic acid)]-beta-cyclodextrin(ACD), was synthesized, and a new sensitive fluorescence identification reaction was studied based on the reaction of Cr2O7(2-) with compound ACD in NaAc-HAc buffer medium at pH 4.90. Under optimal conditions the determination limit was 1.26 microg x L(-1). The linear range was 5.20-1040 microg x L(-1). This method has been applied to the determination of trace amounts of chromium (VI) in electroplating liquor, electroplating waste water with satisfactory results."
1576888,Yu et al. 2005,[Kinetic spectrophotometric determination of trace chromium(VI) with sensitized function of microemulsion],"A sensitive catalytic spectrophotometric method for determining microg x L(-1) of chromium(VI) has been developed. The method, based on the catalytic effect of Cr(VI)on the oxidation of aligarin red with hydrogen peroxide, was monitored spctrophotornetrically in the medium of microemulsion which consists of CTMAB, n-pentanol, n-heptane and water. The variables affecting the rate of the reaction were investigated. The linearity range of the calibration graph is dependent on the reaction temperature. The sensitivity of this method is 72.5% higher in the microemulsion medium than in CTMAB medium. The apparent active energy of the catalytic reaction is 55.7 kJ x mol(-1). The calibration graph is linear for 2.4-75 microg x L(-1) Cr(VI)at 80 degrees C, the detection limit is 4.27 x 10(-10) g x mL(-1), and the relative standard deviation of eleven determinations of 60 microg x L(-1) Cr(VI)was 1.84%. The method has been successfully applied to the determination of chromium(IV) in the electroplating waste water.","[Kinetic spectrophotometric determination of trace chromium(VI) with sensitized function of microemulsion] Abs: A sensitive catalytic spectrophotometric method for determining microg x L(-1) of chromium(VI) has been developed. The method, based on the catalytic effect of Cr(VI)on the oxidation of aligarin red with hydrogen peroxide, was monitored spctrophotornetrically in the medium of microemulsion which consists of CTMAB, n-pentanol, n-heptane and water. The variables affecting the rate of the reaction were investigated. The linearity range of the calibration graph is dependent on the reaction temperature. The sensitivity of this method is 72.5% higher in the microemulsion medium than in CTMAB medium. The apparent active energy of the catalytic reaction is 55.7 kJ x mol(-1). The calibration graph is linear for 2.4-75 microg x L(-1) Cr(VI)at 80 degrees C, the detection limit is 4.27 x 10(-10) g x mL(-1), and the relative standard deviation of eleven determinations of 60 microg x L(-1) Cr(VI)was 1.84%. The method has been successfully applied to the determination of chromium(IV) in the electroplating waste water."
1576887,Yoshikawa and  Hara 1980,[Distribution of chromium in organs of mice injected subcutaneously daily with trivalent and hexavalent chromium (author's transl)],,[Distribution of chromium in organs of mice injected subcutaneously daily with trivalent and hexavalent chromium (author's transl)] Abs: 
1576885,Yetis et al. 1998,Effect of shock chromium(VI) load on the activated sludge process,"BIOSIS COPYRIGHT: BIOL ABS. The effects of shock doses of Cr(VI) on activated sludge process operating at a fixed dilution rate (0.12 h-1) without recycle has been investigated. Different levels of Cr(VI) (1.0, 2.0, 3.0, 5.0, 10.0, 25.0 and 50.0 mg/l) were suddenly dosed to activated sludge units, operating at steady state with a synthetic wastewater devoid of chromium and continued until a new steady state has been reached. The results have shown that Cr(VI) even at very low dosages of 1.0 and 2.0 mg/l was toxic to the ac caused immediate adverse effects, and dramatic reductions in COD removal efficiency have been observed. The time elapsed to reach a new steady state after the shock, has been observed to increase with increasing Cr(VI) dosages. However, the shock injection of 50.0 mg/l Cr(VI) caused complete destruction of microbial population and lead to oscillations in in effluent COD concentration without a new steady state taking place even after 1000 h (=120*hydraulic retention time).","Effect of shock chromium(VI) load on the activated sludge process Abs: BIOSIS COPYRIGHT: BIOL ABS. The effects of shock doses of Cr(VI) on activated sludge process operating at a fixed dilution rate (0.12 h-1) without recycle has been investigated. Different levels of Cr(VI) (1.0, 2.0, 3.0, 5.0, 10.0, 25.0 and 50.0 mg/l) were suddenly dosed to activated sludge units, operating at steady state with a synthetic wastewater devoid of chromium and continued until a new steady state has been reached. The results have shown that Cr(VI) even at very low dosages of 1.0 and 2.0 mg/l was toxic to the ac caused immediate adverse effects, and dramatic reductions in COD removal efficiency have been observed. The time elapsed to reach a new steady state after the shock, has been observed to increase with increasing Cr(VI) dosages. However, the shock injection of 50.0 mg/l Cr(VI) caused complete destruction of microbial population and lead to oscillations in in effluent COD concentration without a new steady state taking place even after 1000 h (=120*hydraulic retention time)."
1576884,Ye and  Fu 1992,Inquisition of toxicity of ions in activated sludge with inhibition coefficient,"BIOSIS COPYRIGHT: BIOL ABS. In this work, a method of measurement of inhibition coefficient, Ki, of metals within activated sludge has been proposed. It can be used in laboratory and water treatment plant for the purpose of determination of heavy metal toxicity on biological water treatment efficiency. In this method, the respiration rate of activated sludge in present of heavy metal was gotten with dissolved oxygen values. The values of Ki for Copper Cu2+, Nickel Ni2+, Cadmium Cd++, Lead Pb2+, Chromium Cr6+, Cyanide CN-, and Zinc Zn2+ were determined, respectively. The toxic order of these ions were CN- Cu2+ Ni2+ Cr6+ Zn2+ C12+ Pb2+. The effects of substrate concentration and MLSS on Ki were investigated. As substrate concentration was beyond 200 mgL-1, the change of it would not affect the value of Ki, and nor do the change of MLSS.","Inquisition of toxicity of ions in activated sludge with inhibition coefficient Abs: BIOSIS COPYRIGHT: BIOL ABS. In this work, a method of measurement of inhibition coefficient, Ki, of metals within activated sludge has been proposed. It can be used in laboratory and water treatment plant for the purpose of determination of heavy metal toxicity on biological water treatment efficiency. In this method, the respiration rate of activated sludge in present of heavy metal was gotten with dissolved oxygen values. The values of Ki for Copper Cu2+, Nickel Ni2+, Cadmium Cd++, Lead Pb2+, Chromium Cr6+, Cyanide CN-, and Zinc Zn2+ were determined, respectively. The toxic order of these ions were CN- Cu2+ Ni2+ Cr6+ Zn2+ C12+ Pb2+. The effects of substrate concentration and MLSS on Ki were investigated. As substrate concentration was beyond 200 mgL-1, the change of it would not affect the value of Ki, and nor do the change of MLSS."
1576883,Yassini et al. 1997,CARCINOGENIC CONSTITUENTS IN LEATHER AND TEXTILE SAMPLES,BIOSIS COPYRIGHT: BIOL ABS. RRM MEETING ABSTRACT HUMAN POLLUTION AZO DYES CARCINOGEN LEATHER SAMPLES TEXTILE SAMPLES TUMOR BIOLOGY CHROMIUMIII CHROMIUMVI NITROSAMINES NITROSODIMETHYLAMINE NITROSOBUTYLAMINE NITROSOMORPHOLINE BENZIDINE 3 3'-DICHLOROBENZIDINE CARCINOGENIC CONSTITUENTS,CARCINOGENIC CONSTITUENTS IN LEATHER AND TEXTILE SAMPLES Abs: BIOSIS COPYRIGHT: BIOL ABS. RRM MEETING ABSTRACT HUMAN POLLUTION AZO DYES CARCINOGEN LEATHER SAMPLES TEXTILE SAMPLES TUMOR BIOLOGY CHROMIUMIII CHROMIUMVI NITROSAMINES NITROSODIMETHYLAMINE NITROSOBUTYLAMINE NITROSOMORPHOLINE BENZIDINE 3 3'-DICHLOROBENZIDINE CARCINOGENIC CONSTITUENTS
1576882,Xie et al. 1995,Study on the treatment of chromium wastewater using modified woodflour,"BIOSIS COPYRIGHT: BIOL ABS. The best technical conditions of preparation have been obtained by factorial design experiment. The modified woodflour increases reducibility and then it can reduce Cr(VI) to Cr3+. The maximum reducibility of modified woodflour comes up to 490 mg Cr(VI) per gram. Let chromium wastewater passeo through the column which is filled with modified woodflour. the reduction rate of Cr(VI) is more than 99.5 per cent when the contact time is over than 6 min. The Cr3+ can be retrieved by precipitating with Ca (OH)2. This method is simple, cheap and has no secondary pollutant.","Study on the treatment of chromium wastewater using modified woodflour Abs: BIOSIS COPYRIGHT: BIOL ABS. The best technical conditions of preparation have been obtained by factorial design experiment. The modified woodflour increases reducibility and then it can reduce Cr(VI) to Cr3+. The maximum reducibility of modified woodflour comes up to 490 mg Cr(VI) per gram. Let chromium wastewater passeo through the column which is filled with modified woodflour. the reduction rate of Cr(VI) is more than 99.5 per cent when the contact time is over than 6 min. The Cr3+ can be retrieved by precipitating with Ca (OH)2. This method is simple, cheap and has no secondary pollutant."
1576881,Wepener et al. 1992,The effect of hexavalent chromium at different pH values on the carbohydrate metabolism of Tilapia sparrmanii (Cichlidae),"BIOSIS COPYRIGHT: BIOL ABS. The effect of hexavalent chromium at different pH values on the carbohydrate metabolism of Tilapia sparrmanii was investigated. The indicator organisms were exposed to Cr(VI) for short and long-term exposures, after which the blood glucose levels and activities of pyruvate kinase, isocitrate dehydrogenase and glucose-6-phosphate dehydrogenase were determined. It was found that short-term exposures of Cr(VI) at an acidic medium caused an increase in energy production and glucose concentrations. Long-term exposures led to exhaustion of carbohydrate reserves, which necessitated the formation of additional energy compounds.","The effect of hexavalent chromium at different pH values on the carbohydrate metabolism of Tilapia sparrmanii (Cichlidae) Abs: BIOSIS COPYRIGHT: BIOL ABS. The effect of hexavalent chromium at different pH values on the carbohydrate metabolism of Tilapia sparrmanii was investigated. The indicator organisms were exposed to Cr(VI) for short and long-term exposures, after which the blood glucose levels and activities of pyruvate kinase, isocitrate dehydrogenase and glucose-6-phosphate dehydrogenase were determined. It was found that short-term exposures of Cr(VI) at an acidic medium caused an increase in energy production and glucose concentrations. Long-term exposures led to exhaustion of carbohydrate reserves, which necessitated the formation of additional energy compounds."
1576880,Wu and  Wada 1981,[Studies on a specific chromium binding substance (a low-molecular-weight chromium binding substance) in urine (author's transl)],"The aim of this study was to identify a specific substance [a Low-Molecular-Weight Chromium binding substance (LMW Cr)] in normal urine and also to clarify the various factors affecting chromium to bind this substance in urine. The results obtained were as follows: 1. Normal human and rat urines contained unsaturated LMW Cr similar to that found in the liver or other organs of rabbits and dogs. The amount of chromium bound in vitro to the unsaturated LMW Cr in normal human urine was 14.81 +/- 1.84 microgram/ml urine when urine was incubated with trivalent chromium for 30 minutes at 37 degrees C. 2. Higher amounts of chromium were bound to LMW Cr in normal urine a 37 degrees C than at 24 degrees C, in acidic state of urine than in alkaline state, and when trivalent chromium was added to the incubation mixture than when hexavalent chromium was added. Chromium contained in LMW Cr was supposed to be trivalent. Furthermore, boiling urine at 100 degrees C for 10 minutes did not reduce the chromium binding capacity of LMW Cr in urine. These results indicate that LMW Cr in urine binds chromium by a chemical reaction. 3. Amounts of chromium bound to LMW Cr in urine obtained 3 hrs after intraperitoneal injection of 200 mumole K2Cr2O7 to a rat were much higher than amounts of chromium bound in vitro to LMW Cr in normal urine during 3 hrs incubation of the urine with K2Cr2O7. This suggests that most of excessively absorbed chromium is excreted into urine after being bound to LMW Cr in organs. 4. Urine from patients with chronic nephritis excreted a part of added chromium bound to high molecular weight fractions corresponding to peaks of UV absorption.","[Studies on a specific chromium binding substance (a low-molecular-weight chromium binding substance) in urine (author's transl)] Abs: The aim of this study was to identify a specific substance [a Low-Molecular-Weight Chromium binding substance (LMW Cr)] in normal urine and also to clarify the various factors affecting chromium to bind this substance in urine. The results obtained were as follows: 1. Normal human and rat urines contained unsaturated LMW Cr similar to that found in the liver or other organs of rabbits and dogs. The amount of chromium bound in vitro to the unsaturated LMW Cr in normal human urine was 14.81 +/- 1.84 microgram/ml urine when urine was incubated with trivalent chromium for 30 minutes at 37 degrees C. 2. Higher amounts of chromium were bound to LMW Cr in normal urine a 37 degrees C than at 24 degrees C, in acidic state of urine than in alkaline state, and when trivalent chromium was added to the incubation mixture than when hexavalent chromium was added. Chromium contained in LMW Cr was supposed to be trivalent. Furthermore, boiling urine at 100 degrees C for 10 minutes did not reduce the chromium binding capacity of LMW Cr in urine. These results indicate that LMW Cr in urine binds chromium by a chemical reaction. 3. Amounts of chromium bound to LMW Cr in urine obtained 3 hrs after intraperitoneal injection of 200 mumole K2Cr2O7 to a rat were much higher than amounts of chromium bound in vitro to LMW Cr in normal urine during 3 hrs incubation of the urine with K2Cr2O7. This suggests that most of excessively absorbed chromium is excreted into urine after being bound to LMW Cr in organs. 4. Urine from patients with chronic nephritis excreted a part of added chromium bound to high molecular weight fractions corresponding to peaks of UV absorption."
1576879,Wang and  Et 1995,"Sequential determination of trace chromium(VI), nickel and zinc in electroplating waste waters by flow-injection spectrophotometry","BIOSIS COPYRIGHT: BIOL ABS. An automated flow-injection system is described for the sequential spectrophotometric determination of trace Cr (IV), Zn and Ni in waste waters. The sample analysis frequency is 60h-1 and the detection limit is 0.1 mg(Cr), 0.2mg/L(Zn), and 0.3mg/L(Ni), respectively. The relative standard deviation is around 1%. Results obtained with the proposed method are in a good agreement with the standard manual spectrophotometric methods.","Sequential determination of trace chromium(VI), nickel and zinc in electroplating waste waters by flow-injection spectrophotometry Abs: BIOSIS COPYRIGHT: BIOL ABS. An automated flow-injection system is described for the sequential spectrophotometric determination of trace Cr (IV), Zn and Ni in waste waters. The sample analysis frequency is 60h-1 and the detection limit is 0.1 mg(Cr), 0.2mg/L(Zn), and 0.3mg/L(Ni), respectively. The relative standard deviation is around 1%. Results obtained with the proposed method are in a good agreement with the standard manual spectrophotometric methods."
1576878,Wang et al. 1991,Inhibition of chromium to the anaerobic digestion,"BIOSIS COPYRIGHT: BIOL ABS. The inhibition of Chromium ion to anaerobic digestion process was studied. The major toxicity to the anaerobic system was caused by the dissolved Chromium ion in the digestion system. When the daily addition dosage of Cr+3 to the digestion system was less than 20mg, between 36-109mg/L and higher than 141mg/L. Gas production would be reduced by less than 20%, 20-40% or higher than 40%, corresponding to light, significant, and serious inhibition effects, respectively. There was no inhibition observed when the daily addition dosage of Cr+6 was less than 14mg/L, while the daily addition of Cr+6 was reached to 36mg/L and more than 70mg/L, the inhibition effects were significant and serious, respectively. When the percentages of daily addition amount of Cr+3 and Cr+6 in active sludge (dry weight) were less than 0.1% and 0.04%, it did not show any effect on the digestion process. In order to keep good running of the anaerobic digestion system, the concentration of dissolved C","Inhibition of chromium to the anaerobic digestion Abs: BIOSIS COPYRIGHT: BIOL ABS. The inhibition of Chromium ion to anaerobic digestion process was studied. The major toxicity to the anaerobic system was caused by the dissolved Chromium ion in the digestion system. When the daily addition dosage of Cr+3 to the digestion system was less than 20mg, between 36-109mg/L and higher than 141mg/L. Gas production would be reduced by less than 20%, 20-40% or higher than 40%, corresponding to light, significant, and serious inhibition effects, respectively. There was no inhibition observed when the daily addition dosage of Cr+6 was less than 14mg/L, while the daily addition of Cr+6 was reached to 36mg/L and more than 70mg/L, the inhibition effects were significant and serious, respectively. When the percentages of daily addition amount of Cr+3 and Cr+6 in active sludge (dry weight) were less than 0.1% and 0.04%, it did not show any effect on the digestion process. In order to keep good running of the anaerobic digestion system, the concentration of dissolved C"
1576877,Vandenbalck and  Patriarche 1984,Differential pulse polarographic microdetermination of chromium(VI) in industrial cements,"HEEP COPYRIGHT: BIOL ABS. Toxicological literature often mentions that Cr (VI), present and added to cements for technical reasons, induces dermatosis (in humans). Good analytical techniques are not available. The D.P.P. (differential pulse polarography) method proposed for the microdetermination of Cr (VI) in cements is fast and selective. The cation is solubilized by stirring the cement with distilled water. After filtration, the solution was submitted to D.P.P. Generally, samples analyzed contained between 1 and 12 mg of Cr (VI) per kg of cement. The potential peak was -0.19 V vs. S.C.E. for the pure Cr (VI) solution and was shifted toward between -0.25 and -0.30 V vs. S.C.E. when Cr (VI) was extracted from real cement samples. The detection limit was 0.3 ppm.","Differential pulse polarographic microdetermination of chromium(VI) in industrial cements Abs: HEEP COPYRIGHT: BIOL ABS. Toxicological literature often mentions that Cr (VI), present and added to cements for technical reasons, induces dermatosis (in humans). Good analytical techniques are not available. The D.P.P. (differential pulse polarography) method proposed for the microdetermination of Cr (VI) in cements is fast and selective. The cation is solubilized by stirring the cement with distilled water. After filtration, the solution was submitted to D.P.P. Generally, samples analyzed contained between 1 and 12 mg of Cr (VI) per kg of cement. The potential peak was -0.19 V vs. S.C.E. for the pure Cr (VI) solution and was shifted toward between -0.25 and -0.30 V vs. S.C.E. when Cr (VI) was extracted from real cement samples. The detection limit was 0.3 ppm."
1576876,Vishniakov et al. 1992,[The biological action of chromium in relation to its valency],"The biological action of chromium in the human or animal organism depends on valency: normal physiological activity is displayed at the expense of CrIII, but toxic activity is more characteristic of CrVI. In the digestive tract and pulmonary tissue CrVI may restore in CrIII.","[The biological action of chromium in relation to its valency] Abs: The biological action of chromium in the human or animal organism depends on valency: normal physiological activity is displayed at the expense of CrIII, but toxic activity is more characteristic of CrVI. In the digestive tract and pulmonary tissue CrVI may restore in CrIII."
1576875,Y-M et al. 1997,The sorption of chromate in soil (1),"BIOSIS COPYRIGHT: BIOL ABS. Cr(VI) is a toxic element for plants and animals. Chromate is an anionic species, and its behavior in soils is quite different from that of other heavy metals. The negative charge of soil particles in neutral and alkaline soils cannot sorb chromate. However, in acid soils, both the broken edge of kaolinite and Al- and Fe oxides bearing a positive charge can sorb chromate anions. The bonding strength of chromate anion is not like that of specific phosphate and sulfate anions; thus, chromate is easily desorbed by these specific anions and leached through soil column. Once Cr(VI) contaminates soils, it can become mobile in the soil profiles and cause a hazard for ground water. To understand the physic/chemical characteristics of Cr(VI) and to resolve pollution problems, it is necessary to study the adsorption behavior of Cr(VI) in soils. The Tao-Yung acid soil and Si-Lo alkaline soil were employed for the study of Cr(VI) sorption. Experimental results indicated that Cr(VI)","The sorption of chromate in soil (1) Abs: BIOSIS COPYRIGHT: BIOL ABS. Cr(VI) is a toxic element for plants and animals. Chromate is an anionic species, and its behavior in soils is quite different from that of other heavy metals. The negative charge of soil particles in neutral and alkaline soils cannot sorb chromate. However, in acid soils, both the broken edge of kaolinite and Al- and Fe oxides bearing a positive charge can sorb chromate anions. The bonding strength of chromate anion is not like that of specific phosphate and sulfate anions; thus, chromate is easily desorbed by these specific anions and leached through soil column. Once Cr(VI) contaminates soils, it can become mobile in the soil profiles and cause a hazard for ground water. To understand the physic/chemical characteristics of Cr(VI) and to resolve pollution problems, it is necessary to study the adsorption behavior of Cr(VI) in soils. The Tao-Yung acid soil and Si-Lo alkaline soil were employed for the study of Cr(VI) sorption. Experimental results indicated that Cr(VI)"
1576873,Tabata 1979,RELATIONSHIP BETWEEN ACUTE AND LONG-TERM TOXICITY OF WATER POLLUTANTS TO AQUATIC ORGANISMS,HEEP COPYRIGHT: BIOL ABS. REVIEW FISH CYANIDES CHLORINE SULFIDES AMMONIA LEAD HEXAVALENT CHROMIUM METHYL MERCURY JAPAN USA FRESH WATER MARINE LC-50,RELATIONSHIP BETWEEN ACUTE AND LONG-TERM TOXICITY OF WATER POLLUTANTS TO AQUATIC ORGANISMS Abs: HEEP COPYRIGHT: BIOL ABS. REVIEW FISH CYANIDES CHLORINE SULFIDES AMMONIA LEAD HEXAVALENT CHROMIUM METHYL MERCURY JAPAN USA FRESH WATER MARINE LC-50
1576872,Susa et al. 1977,[Comparative cytotoxic effects of hexavalent and trivalent chromium compounds on cultured cells (author's transl)],,[Comparative cytotoxic effects of hexavalent and trivalent chromium compounds on cultured cells (author's transl)] Abs: 
1576815,Suess and  Russ 1988,THE SEPARATION OF COPPER NICKEL CHROMIUM ZINC AND SILVER FROM ELECTROPLATING WASTEWATERS IN ION EXCHANGE RESIN AND ACTIVATED CARBON 1. SEPARATION OF COPPER NICKEL CHROMIUM-VI FROM ACID ELECTROLYTE WASTEWATERS,BIOSIS COPYRIGHT: BIOL ABS. RRM EAST GERMANY HYDROXIDE PRECIPITATION SLUDGE ACIDIC CATION EXCHANGE,THE SEPARATION OF COPPER NICKEL CHROMIUM ZINC AND SILVER FROM ELECTROPLATING WASTEWATERS IN ION EXCHANGE RESIN AND ACTIVATED CARBON 1. SEPARATION OF COPPER NICKEL CHROMIUM-VI FROM ACID ELECTROLYTE WASTEWATERS Abs: BIOSIS COPYRIGHT: BIOL ABS. RRM EAST GERMANY HYDROXIDE PRECIPITATION SLUDGE ACIDIC CATION EXCHANGE
1576814,Bondarenko and  Starodubova 1981,CYTO TOXIC EFFECT OF HEXAVALENT CHROMIUM IN HUMAN AND ANIMAL CELL CULTURES,HEEP COPYRIGHT: BIOL ABS. NOTE RABBIT GUINEA-PIG BONE MARROW LEUKOCYTE MACROPHAGE SPERMATOZOA,CYTO TOXIC EFFECT OF HEXAVALENT CHROMIUM IN HUMAN AND ANIMAL CELL CULTURES Abs: HEEP COPYRIGHT: BIOL ABS. NOTE RABBIT GUINEA-PIG BONE MARROW LEUKOCYTE MACROPHAGE SPERMATOZOA
1576813,Skornyakova et al. 1986,HYGIENIC STANDARDIZATION OF HEXAVALENT CHROMIUM IN WATER BODIES ON THE BASIS OF ITS SKIN-RESORPTIVE EFFECT,BIOSIS COPYRIGHT: BIOL ABS. RRM RAT EMBRYOTOXICITY MUTAGEN METAL POLLUTION ORAL DERMAL,HYGIENIC STANDARDIZATION OF HEXAVALENT CHROMIUM IN WATER BODIES ON THE BASIS OF ITS SKIN-RESORPTIVE EFFECT Abs: BIOSIS COPYRIGHT: BIOL ABS. RRM RAT EMBRYOTOXICITY MUTAGEN METAL POLLUTION ORAL DERMAL
1576812,Simonova et al. 1985,A STUDY OF THE ADAPTIVE PROPERTIES OF AN AEROMONAS-DECHROMATICA KS-11 CULTURE FOR THE REMOVAL OF HEXAVALENT CHROMIUM FROM WATER,BIOSIS COPYRIGHT: BIOL ABS. RRM CARBON NUTRITION SOURCE PH,A STUDY OF THE ADAPTIVE PROPERTIES OF AN AEROMONAS-DECHROMATICA KS-11 CULTURE FOR THE REMOVAL OF HEXAVALENT CHROMIUM FROM WATER Abs: BIOSIS COPYRIGHT: BIOL ABS. RRM CARBON NUTRITION SOURCE PH
1576811,Sun and  You 2004,[Extraction catalytic spectrophotometric determination of trace chromium by synergetic catalytic effect],"In this paper, a new synergetic extraction catalytic spectrophotometric method for the determination of trace chromium was studied. The method is based on the iron(III) and chromium(VI) synergetic catalyzed oxidation of o-aminophenol by hydrogen peroxide in weak acidic medium at pH 5.5. The reaction time, concentration of o-aminophenol in aqueous phase, and degree of reaction were controlled by extraction equilibrium. The absorbance of organic phase was measured at 424 nm. The linear range of the method is 0.0010-0.90 mg x L(-1). The detection limit for chromium(VI) is 5.0 x 10(-6) g x L(-1). The relative standard deviation (n = 11) for 0.20 microg x mL(-1) level of Cr(VI) is 2.0%. The method has been applied to the determination of chromium in tap water and waste water with satisfactory results.","[Extraction catalytic spectrophotometric determination of trace chromium by synergetic catalytic effect] Abs: In this paper, a new synergetic extraction catalytic spectrophotometric method for the determination of trace chromium was studied. The method is based on the iron(III) and chromium(VI) synergetic catalyzed oxidation of o-aminophenol by hydrogen peroxide in weak acidic medium at pH 5.5. The reaction time, concentration of o-aminophenol in aqueous phase, and degree of reaction were controlled by extraction equilibrium. The absorbance of organic phase was measured at 424 nm. The linear range of the method is 0.0010-0.90 mg x L(-1). The detection limit for chromium(VI) is 5.0 x 10(-6) g x L(-1). The relative standard deviation (n = 11) for 0.20 microg x mL(-1) level of Cr(VI) is 2.0%. The method has been applied to the determination of chromium in tap water and waste water with satisfactory results."
1576810,Shawket et al. 2005,[Speciation analysis of chromium(VI) and chromium(III) in water sample using flame atomic absorption spectrometry with TOA-benzene extraction separation system],"A rapid and sensitive method for the sequential determination of Cr(VI) and Cr(III) in water samples based on flame atomic absorption spectrometry with TOA-benzene extraction separation system has been developed. In the H2SO4 medium. Cr(VI) in sample solution was extracted into the organic phase by using the TOA-Benzene and Cr(III) remained in the water phase. Cr(VI) in the organic phase and Cr(III) in the water phase were determined separately by AAS. This method is simple, fast and of microscale. The results obtained by this method agreed well with those obtained by conventional method. The recoveries are 95.0%-102% for Cr(VI) and 94.8-103% for Cr(III). The relative standard deviations were 2.9% for Cr(VI) and 2.6% for Cr(Ill). The system has enrichment effect for Cr(VI), and the detection limits are 6.6 microg x L(-1) for Cr(VI) and 0.20 mg x L(-1) for Cr(III). The maximum extracted amount of Cr(VI) by TOA was 4.6 mg x mL(-1).","[Speciation analysis of chromium(VI) and chromium(III) in water sample using flame atomic absorption spectrometry with TOA-benzene extraction separation system] Abs: A rapid and sensitive method for the sequential determination of Cr(VI) and Cr(III) in water samples based on flame atomic absorption spectrometry with TOA-benzene extraction separation system has been developed. In the H2SO4 medium. Cr(VI) in sample solution was extracted into the organic phase by using the TOA-Benzene and Cr(III) remained in the water phase. Cr(VI) in the organic phase and Cr(III) in the water phase were determined separately by AAS. This method is simple, fast and of microscale. The results obtained by this method agreed well with those obtained by conventional method. The recoveries are 95.0%-102% for Cr(VI) and 94.8-103% for Cr(III). The relative standard deviations were 2.9% for Cr(VI) and 2.6% for Cr(Ill). The system has enrichment effect for Cr(VI), and the detection limits are 6.6 microg x L(-1) for Cr(VI) and 0.20 mg x L(-1) for Cr(III). The maximum extracted amount of Cr(VI) by TOA was 4.6 mg x mL(-1)."
1576809,Schwarz and  Spier 1960,[The percutaneous absorption of trivalent and hexavalent chromium (Cr-51). On the pathogenesis of contact eczema],,[The percutaneous absorption of trivalent and hexavalent chromium (Cr-51). On the pathogenesis of contact eczema] Abs: 
1576808,Salgado P E et al. 1986,CHANGES IN THE ENZYME ACTIVITY OF DELTA AMINOLEVULINIC ACID DEHYDRATASE IN RAT ERYTHROCYTE BY METALS,BIOSIS COPYRIGHT: BIOL ABS. RRM LEAD COPPER ZINC CHROMIUM METAL INTERACTION,CHANGES IN THE ENZYME ACTIVITY OF DELTA AMINOLEVULINIC ACID DEHYDRATASE IN RAT ERYTHROCYTE BY METALS Abs: BIOSIS COPYRIGHT: BIOL ABS. RRM LEAD COPPER ZINC CHROMIUM METAL INTERACTION
1576807,Sakka et al. 1988,ISOLATION AND CHARACTERIZATION OF BACTERIA WITH EXTRAORDINARY RESISTANCE TO HEXAVALENT CHROMIUM,BIOSIS COPYRIGHT: BIOL ABS. RRM NOTE PERMEATION MEMBRANE BARRIER,ISOLATION AND CHARACTERIZATION OF BACTERIA WITH EXTRAORDINARY RESISTANCE TO HEXAVALENT CHROMIUM Abs: BIOSIS COPYRIGHT: BIOL ABS. RRM NOTE PERMEATION MEMBRANE BARRIER
1576806,Sag et al. 1998,"Competitive biosorption of chromium(VI), iron(III) and copper(II) ions from binary metal mixtures by R. arrhizus and C. vulgaris","BIOSIS COPYRIGHT: BIOL ABS. In this study, the simultaneous adsorption process of Cr(VI), Fe(III) by R. arrhizus and C. vulgaris and Cu(II) in pairs of metal mixtures were investigated and compared to single component systems. The capabilities of the fungal and the algal biomass to bind two metals simultaneously in solution are shown as a function of pH, metal combinations and levels of metal concentration. The effects of the co-presence of Cr(VI)-Fe(III) and Cr(VI)-Cu(II) ions together in aquatic solutions on the biosorption of Cr(VI). Fe(III) and Cu(II) ions were investigated in terms of initial rates of biosorption and equilibrium metal removal. Optimum pH for the biosorption of Cr(VI) and Fe(III) was determined as 2.0 whereas higher biosorptive uptake of Cu(II) was obtained at pH 4.0. Since the initial biosorption rates and equilibrium metal removal decreased with increasing concentration of the accompanying metal ion, the interactive effects of Cr(VI)-Fe(III) and Cr(VI)-Cu(II) on both microor","Competitive biosorption of chromium(VI), iron(III) and copper(II) ions from binary metal mixtures by R. arrhizus and C. vulgaris Abs: BIOSIS COPYRIGHT: BIOL ABS. In this study, the simultaneous adsorption process of Cr(VI), Fe(III) by R. arrhizus and C. vulgaris and Cu(II) in pairs of metal mixtures were investigated and compared to single component systems. The capabilities of the fungal and the algal biomass to bind two metals simultaneously in solution are shown as a function of pH, metal combinations and levels of metal concentration. The effects of the co-presence of Cr(VI)-Fe(III) and Cr(VI)-Cu(II) ions together in aquatic solutions on the biosorption of Cr(VI). Fe(III) and Cu(II) ions were investigated in terms of initial rates of biosorption and equilibrium metal removal. Optimum pH for the biosorption of Cr(VI) and Fe(III) was determined as 2.0 whereas higher biosorptive uptake of Cu(II) was obtained at pH 4.0. Since the initial biosorption rates and equilibrium metal removal decreased with increasing concentration of the accompanying metal ion, the interactive effects of Cr(VI)-Fe(III) and Cr(VI)-Cu(II) on both microor"
1576805,Ryk and  Budanova 1983,Specific haemolysis reaction as an indicator of sensitisation to occupational allergens,"Allergens are identified by adding solutions of the presumed antigen or hapten to whole blood from the victim of a given allergy, and measuring free haemoglobin in the sample after an incubation period. In a typical experiment, hexavalent chromium caused up to 60% increases in the free haemoglobin concentration of blood from persons with bronchial asthma due to chromium compounds, but produced little haemolysis in blood samples from healthy controls or from persons suffering from bronchial asthma of different aetiology. When Candida antigen was used instead of chromium, a 50% increase in haemolysis was seen. The free haemoglobin is measured photometrically after conversion to cyanohaemoglobin; the conversion stabilises the samples so that they need not be analysed immediately after incubation.","Specific haemolysis reaction as an indicator of sensitisation to occupational allergens Abs: Allergens are identified by adding solutions of the presumed antigen or hapten to whole blood from the victim of a given allergy, and measuring free haemoglobin in the sample after an incubation period. In a typical experiment, hexavalent chromium caused up to 60% increases in the free haemoglobin concentration of blood from persons with bronchial asthma due to chromium compounds, but produced little haemolysis in blood samples from healthy controls or from persons suffering from bronchial asthma of different aetiology. When Candida antigen was used instead of chromium, a 50% increase in haemolysis was seen. The free haemoglobin is measured photometrically after conversion to cyanohaemoglobin; the conversion stabilises the samples so that they need not be analysed immediately after incubation."
1576804,Ruan and  Et 1990,Application of inductest in the research of environmental mutagens,BIOSIS COPYRIGHT: BIOL ABS. The toxicological effect of Cr(VI) on some biochemical parameters in pepper were studied both in soil culture and in nutrient cultural experiments. The treatments of the heavy metals decreased fresh weight and promoted senescence of the pepper plant by decreasing chlorophyll and activities of superoxide dismutase and catalase as well as increasing iron content and peroxidase activity over control values.,Application of inductest in the research of environmental mutagens Abs: BIOSIS COPYRIGHT: BIOL ABS. The toxicological effect of Cr(VI) on some biochemical parameters in pepper were studied both in soil culture and in nutrient cultural experiments. The treatments of the heavy metals decreased fresh weight and promoted senescence of the pepper plant by decreasing chlorophyll and activities of superoxide dismutase and catalase as well as increasing iron content and peroxidase activity over control values.
1576803,Pirog 1997,Role of Acinetobacter sp. exopolysaccharides in protection against heavy metal ions,"BIOSIS COPYRIGHT: BIOL ABS. Exopolysaccharides (EPS) produced by an Acinetobacter sp. were found to be capable of protecting its cells against heavy metal ions (Cu2+, Pb2+, and Cr3+). In the presence of EPS, exponential cells were more metal-resistant than stationary cells. EPS were not protective with respect to Cd2+ and Cr6+. In addition to EPS production, Acinetobacter sp. probably has other protective mechanisms.","Role of Acinetobacter sp. exopolysaccharides in protection against heavy metal ions Abs: BIOSIS COPYRIGHT: BIOL ABS. Exopolysaccharides (EPS) produced by an Acinetobacter sp. were found to be capable of protecting its cells against heavy metal ions (Cu2+, Pb2+, and Cr3+). In the presence of EPS, exponential cells were more metal-resistant than stationary cells. EPS were not protective with respect to Cd2+ and Cr6+. In addition to EPS production, Acinetobacter sp. probably has other protective mechanisms."
1576802,Poli and  Guyotjeannin 1960,[Nasal ulcerations caused by paints with zinc chromate base],,[Nasal ulcerations caused by paints with zinc chromate base] Abs: 
1576801,Pavlov and  Zyabkina 1981,DETERMINATION OF CHROMIUM VI IN SOIL AND OTHER ENVIRONMENTAL OBJECTS,HEEP COPYRIGHT: BIOL ABS. NOTE PLANT ORGANISM POLAROGRAPHY METAL POLLUTION,DETERMINATION OF CHROMIUM VI IN SOIL AND OTHER ENVIRONMENTAL OBJECTS Abs: HEEP COPYRIGHT: BIOL ABS. NOTE PLANT ORGANISM POLAROGRAPHY METAL POLLUTION
1576800,Pavlov and  Ziabkina 1981,[Determination of chromium (VI) in the soil and other environmental objects],,[Determination of chromium (VI) in the soil and other environmental objects] Abs: 
1576799,Panchenco and  Turkovskaya 1999,The applicability of surfactant-degrading microorganisms for treatment of multicomponent waste water,"BIOSIS COPYRIGHT: BIOL ABS. The degradation of non-ionic surfactants by free and immobilized cells of degrader strains in model and real waste waters has been studied. The effect of the most widespread acompanying pollutants and cultivation conditions on this process was investigated. The quantitative indices of the qualitative decrease of the microbial purification in the presence of mineral oils, Cu2+, Zn2+, Fe2+, Al3+ ions, metal dust and acrylates are given. The biodegradation of non-ionic surfactants using a complex t","The applicability of surfactant-degrading microorganisms for treatment of multicomponent waste water Abs: BIOSIS COPYRIGHT: BIOL ABS. The degradation of non-ionic surfactants by free and immobilized cells of degrader strains in model and real waste waters has been studied. The effect of the most widespread acompanying pollutants and cultivation conditions on this process was investigated. The quantitative indices of the qualitative decrease of the microbial purification in the presence of mineral oils, Cu2+, Zn2+, Fe2+, Al3+ ions, metal dust and acrylates are given. The biodegradation of non-ionic surfactants using a complex t"
1576798,Pacha and  Piotrowska-Seget 1988,TOXICITY OF SELECTED TRIVALENT AND HEXAVALENT CHROMIUM COMPOUNDS FOR CHLORELLA-PYRENOIDOSA,BIOSIS COPYRIGHT: BIOL ABS. RRM CHROMIUM SULFATE CHROMIUM ACETATE,TOXICITY OF SELECTED TRIVALENT AND HEXAVALENT CHROMIUM COMPOUNDS FOR CHLORELLA-PYRENOIDOSA Abs: BIOSIS COPYRIGHT: BIOL ABS. RRM CHROMIUM SULFATE CHROMIUM ACETATE
1576797,Pacha and  Piotrowska-Seget 1988,INFLUENCE OF TRIVALENT AND HEXAVALENT CHROMIUM ON SCENEDESMUS-ACUTUS,BIOSIS COPYRIGHT: BIOL ABS. RRM DOSE,INFLUENCE OF TRIVALENT AND HEXAVALENT CHROMIUM ON SCENEDESMUS-ACUTUS Abs: BIOSIS COPYRIGHT: BIOL ABS. RRM DOSE
1576796,Pacha and  Galimska-Stypa 1988,ACTION OF TRIVALENT AND HEXAVALENT CHROMIUM COMPOUNDS ON SELECTED GRAM-NEGATIVE AND GRAM-POSITIVE BACTERIA,BIOSIS COPYRIGHT: BIOL ABS. RRM PSEUDOMONAS-PUTIDA ESCHERICHIA-COLI STAPHYLOCOCCUS-AUREUS BACILLUS-SUBTILIS STRONG ACID WEAK ACID,ACTION OF TRIVALENT AND HEXAVALENT CHROMIUM COMPOUNDS ON SELECTED GRAM-NEGATIVE AND GRAM-POSITIVE BACTERIA Abs: BIOSIS COPYRIGHT: BIOL ABS. RRM PSEUDOMONAS-PUTIDA ESCHERICHIA-COLI STAPHYLOCOCCUS-AUREUS BACILLUS-SUBTILIS STRONG ACID WEAK ACID
1576795,Pacha et al. 1988,DECOMPOSITION OF PINE NEEDLES IN SOIL TREATED WITH SELECTED TRIVALENT AND HEXAVALENT CHROMIUM COMPOUNDS,BIOSIS COPYRIGHT: BIOL ABS. RRM ELECTRON MICROSCOPE,DECOMPOSITION OF PINE NEEDLES IN SOIL TREATED WITH SELECTED TRIVALENT AND HEXAVALENT CHROMIUM COMPOUNDS Abs: BIOSIS COPYRIGHT: BIOL ABS. RRM ELECTRON MICROSCOPE
1576794,Pacha and  Baron 1988,PROTEOLYSIS IN SOIL WITH THE ADDITION OF ARTIFICIAL HUMIC ACIDS TREATED WITH SELECTED TRIVALENT AND HEXAVALENT CHROMIUM COMPOUNDS,BIOSIS COPYRIGHT: BIOL ABS. RRM PROTEASE ACTIVITY,PROTEOLYSIS IN SOIL WITH THE ADDITION OF ARTIFICIAL HUMIC ACIDS TREATED WITH SELECTED TRIVALENT AND HEXAVALENT CHROMIUM COMPOUNDS Abs: BIOSIS COPYRIGHT: BIOL ABS. RRM PROTEASE ACTIVITY
1576793,Pacha and  Baron 1988,PROTEOLYTIC ACTIVITY OF SOIL WITH ADDED NATURAL HUMIC ACIDS TREATED WITH SELECTED TRIVALENT AND HEXAVALENT CHROMIUM COMPOUNDS,BIOSIS COPYRIGHT: BIOL ABS. RRM CHROMIUM CHLORIDE SODIUM DICHROMATE,PROTEOLYTIC ACTIVITY OF SOIL WITH ADDED NATURAL HUMIC ACIDS TREATED WITH SELECTED TRIVALENT AND HEXAVALENT CHROMIUM COMPOUNDS Abs: BIOSIS COPYRIGHT: BIOL ABS. RRM CHROMIUM CHLORIDE SODIUM DICHROMATE
1576792,Pacha 1988,INFLUENCE OF TRIVALENT AND HEXAVALENT CHROMIUM COMPOUNDS ON THE ACTIVITY OF SELECTED ENZYMES IN ACID AND ALKALINE SOIL,BIOSIS COPYRIGHT: BIOL ABS. RRM DEHYDROGENASE PROTEASE AMYLASE PHOSPHATASE,INFLUENCE OF TRIVALENT AND HEXAVALENT CHROMIUM COMPOUNDS ON THE ACTIVITY OF SELECTED ENZYMES IN ACID AND ALKALINE SOIL Abs: BIOSIS COPYRIGHT: BIOL ABS. RRM DEHYDROGENASE PROTEASE AMYLASE PHOSPHATASE
1576791,Oldh 1986,THE USE OF NUCLEAR ANALYTICAL METHODS FOR THE DETERMINATION OF HEAVY METALS IN WORKING ENVIRONMENT OF THE WELDING OPERATORS,BIOSIS COPYRIGHT: BIOL ABS. RRM RADIONUCLEOTIDE ROENTGENOFLUORESCENT ANALYSIS NEUTRON ACTIVATION ANALYSIS HIGH-ALLOYED STEEL WELDING,THE USE OF NUCLEAR ANALYTICAL METHODS FOR THE DETERMINATION OF HEAVY METALS IN WORKING ENVIRONMENT OF THE WELDING OPERATORS Abs: BIOSIS COPYRIGHT: BIOL ABS. RRM RADIONUCLEOTIDE ROENTGENOFLUORESCENT ANALYSIS NEUTRON ACTIVATION ANALYSIS HIGH-ALLOYED STEEL WELDING
1576790,Nishioka and  Yagi 1976,MUTAGENESIS OF METALS IN BACTERIA. MAGNESIUM(2+) EFFECT AND METAL RESISTANCE,,MUTAGENESIS OF METALS IN BACTERIA. MAGNESIUM(2+) EFFECT AND METAL RESISTANCE Abs: 
1576789,Mukhambetova L et al. 1987,A STUDY OF BIOGENIC AMINE METABOLISM AND OF THE ACTIVITY OF A NUMBER OF ENZYME-SUBSTRATE SYSTEMS IN THE LIVER TISSUE AND SKIN UNDER THE EXPERIMENTAL EFFECT OF HEXAVALENT CHROMIUM,BIOSIS COPYRIGHT: BIOL ABS. RRM ALLERGIC DERMATOSIS BETA-N ACETYLGLUCOSAMINIDASE MALATE LACTATE DEHYDROGENASE,A STUDY OF BIOGENIC AMINE METABOLISM AND OF THE ACTIVITY OF A NUMBER OF ENZYME-SUBSTRATE SYSTEMS IN THE LIVER TISSUE AND SKIN UNDER THE EXPERIMENTAL EFFECT OF HEXAVALENT CHROMIUM Abs: BIOSIS COPYRIGHT: BIOL ABS. RRM ALLERGIC DERMATOSIS BETA-N ACETYLGLUCOSAMINIDASE MALATE LACTATE DEHYDROGENASE
1576788,Mohr 1983,Toxicity of chromiumIII and chromiumVI and their uptake by grapevines (Vitis vinifera) grown in acid or alkaline soils,"HEEP COPYRIGHT: BIOL ABS. The effect of CrIII or CrVI on the growth and Cr-content of grapevine was investigated in pot trials using soil or quartz sand. The grapevines were injured more severely by CrVI than by CrIII. CrVI was more readily translocated into the leaves than CrIII. The injury caused by CrVI included wilting, chlorosis and reduced shoot growth and increased strongly with increasing soil pH. The grapevines were injured after addition of 50-100 ppm CrVI to an acid soil (pH 4.0) but only 10 ppm CrVI to an alkaline soil (pH 7.7). Grapevines, grown in an acid soil contaminated with 50 ppm CrVI and limed gradually, were also injured with increasing severity as the lime content of the soil increased. This effect was explained by the increasing solubility of CrVI. The latter was easily reduced to CrIII by the organic matter of the soil.","Toxicity of chromiumIII and chromiumVI and their uptake by grapevines (Vitis vinifera) grown in acid or alkaline soils Abs: HEEP COPYRIGHT: BIOL ABS. The effect of CrIII or CrVI on the growth and Cr-content of grapevine was investigated in pot trials using soil or quartz sand. The grapevines were injured more severely by CrVI than by CrIII. CrVI was more readily translocated into the leaves than CrIII. The injury caused by CrVI included wilting, chlorosis and reduced shoot growth and increased strongly with increasing soil pH. The grapevines were injured after addition of 50-100 ppm CrVI to an acid soil (pH 4.0) but only 10 ppm CrVI to an alkaline soil (pH 7.7). Grapevines, grown in an acid soil contaminated with 50 ppm CrVI and limed gradually, were also injured with increasing severity as the lime content of the soil increased. This effect was explained by the increasing solubility of CrVI. The latter was easily reduced to CrIII by the organic matter of the soil."
1576786,Matczak et al. 1986,DETERMINATION OF SEXAVALENT CHROMIUM,BIOSIS COPYRIGHT: BIOL ABS. RRM POLLUTANT DIPHENYLCARBAZIDE IRON,DETERMINATION OF SEXAVALENT CHROMIUM Abs: BIOSIS COPYRIGHT: BIOL ABS. RRM POLLUTANT DIPHENYLCARBAZIDE IRON
1576785,Merkur'eva et al. 1982,[Comparative study of the metabolic reactions to different routes of hexavalent chromium uptake in the body of experimental animals],,[Comparative study of the metabolic reactions to different routes of hexavalent chromium uptake in the body of experimental animals] Abs: 
1576784,Luzzati and  Siragusa 1983,PLANT GROWTH AND CONCENTRATIONS OF CHROMIUM AND NUTRITIVE ELEMENTS IN SOME PLANT SPECIES TREATED WITH HEXAVALENT AND TRIVALENT CHROMIUM,BIOSIS COPYRIGHT: BIOL ABS. RRM AVENA-SATIVA TRIFOLIUM-REPENS RAPHANUS-SATIVUS DAUCUS-CAROTA YIELD PHOSPHORUS POTASSIUM CALCIUM MAGNESIUM,PLANT GROWTH AND CONCENTRATIONS OF CHROMIUM AND NUTRITIVE ELEMENTS IN SOME PLANT SPECIES TREATED WITH HEXAVALENT AND TRIVALENT CHROMIUM Abs: BIOSIS COPYRIGHT: BIOL ABS. RRM AVENA-SATIVA TRIFOLIUM-REPENS RAPHANUS-SATIVUS DAUCUS-CAROTA YIELD PHOSPHORUS POTASSIUM CALCIUM MAGNESIUM
1576783,Liu et al. 1991,Removal of chromium from wastewater with iron-modified corn gluten,BIOSIS COPYRIGHT: BIOL ABS. This paper introduces a new method for the removal of Cr(VI) form wastewater by using Fe-modified corn gluten. The experimental results show that the rate of removal can reach 99.9% at pH 2-10 and flow rate of 5-28 ml/min. and the saturated capacity was determined to be 27 mg/g (measured by Cr(VI)). The results of enlarged test of true wastewater are satisfactory. The adsorbed Cr(VI) can be eluated by NH3H2O(0.3M) and then the material can be reused. In view of the properties of the material the method has the prospect of becoming a cheap and effective one for the treatment of Cr (VI)-containing wastewater.,Removal of chromium from wastewater with iron-modified corn gluten Abs: BIOSIS COPYRIGHT: BIOL ABS. This paper introduces a new method for the removal of Cr(VI) form wastewater by using Fe-modified corn gluten. The experimental results show that the rate of removal can reach 99.9% at pH 2-10 and flow rate of 5-28 ml/min. and the saturated capacity was determined to be 27 mg/g (measured by Cr(VI)). The results of enlarged test of true wastewater are satisfactory. The adsorbed Cr(VI) can be eluated by NH3H2O(0.3M) and then the material can be reused. In view of the properties of the material the method has the prospect of becoming a cheap and effective one for the treatment of Cr (VI)-containing wastewater.
1576782,Matczak and  Przybylska-Stanis?awska 2004,[Determination of fumes and their elements from flux cored arc welding],"<strong>BACKGROUND: </strong>The aim of this work was to assay the concentration levels and composition of welding fumes, released during flux cored arc welding, to assess exposure of welders.<br /><br /><strong>MATERIALS AND METHODS: </strong>Concentrations and welding fume components, such as iron, manganese, chromium (including the soluble and chromium VI), nickel, copper, calcium, aluminium, barium, and fluorides (including hydrogen fluoride) were determined in the air of six industrial plants (shipyards, mechanical engineering plants and a power station) at the breathing zones of the welders who used 10 types of wires during flux cored arc welding. The following determination methods were used: gravimetry (fumes), AAS (metals), and spectrophotometry (chromium VI, fluorides--including hydrogen fluoride).<br /><br /><strong>RESULTS: </strong>The results made it possible to determine the relationship between concentrations of welding fume and its elements, and to assess worker's exposure. Time weighted average concentrations of the welding fumes and its elements at the worker's breathing zone were: mg/m3: dust 0.2-24.3; Fe 0.2-6.7; Mn 0.01-1.8; Cr 0.004-0.5 (mainly Cr III); Ca 0.004-2.5; Ni &lt; or = 0.004; Cu &lt; 0.002-0.05; Al &lt; 0.14-0.4; Ba &lt; 0.14; F- 0.07-0.43.<br /><br /><strong>CONCLUSIONS: </strong>The welders using some types of flux cored welding wires worked in conditions harmful to their health owing to the considerably exceeded TLV value for fume and MAC values for manganese, and occasional slightly excessive MAC values for calcium and iron.","[Determination of fumes and their elements from flux cored arc welding] Abs: <strong>BACKGROUND: </strong>The aim of this work was to assay the concentration levels and composition of welding fumes, released during flux cored arc welding, to assess exposure of welders.<br /><br /><strong>MATERIALS AND METHODS: </strong>Concentrations and welding fume components, such as iron, manganese, chromium (including the soluble and chromium VI), nickel, copper, calcium, aluminium, barium, and fluorides (including hydrogen fluoride) were determined in the air of six industrial plants (shipyards, mechanical engineering plants and a power station) at the breathing zones of the welders who used 10 types of wires during flux cored arc welding. The following determination methods were used: gravimetry (fumes), AAS (metals), and spectrophotometry (chromium VI, fluorides--including hydrogen fluoride).<br /><br /><strong>RESULTS: </strong>The results made it possible to determine the relationship between concentrations of welding fume and its elements, and to assess worker's exposure. Time weighted average concentrations of the welding fumes and its elements at the worker's breathing zone were: mg/m3: dust 0.2-24.3; Fe 0.2-6.7; Mn 0.01-1.8; Cr 0.004-0.5 (mainly Cr III); Ca 0.004-2.5; Ni &lt; or = 0.004; Cu &lt; 0.002-0.05; Al &lt; 0.14-0.4; Ba &lt; 0.14; F- 0.07-0.43.<br /><br /><strong>CONCLUSIONS: </strong>The welders using some types of flux cored welding wires worked in conditions harmful to their health owing to the considerably exceeded TLV value for fume and MAC values for manganese, and occasional slightly excessive MAC values for calcium and iron."
1576781,Lozovaia et al. 2004,[Effect of chromium (VI) on growth physiology and sorptional capacity of yeast],"Resistance of 7 yeast species (7 strains) to various chrome concentrations in the medium and their sorptional activity have been studied. It is shown that the biomass of the yeast Williopsis californica UKM-248, Candida krusei UKM-61t under their concentration in the medium of 200 and 500 mg/l of Cr6+ is 0.74 and 0.45 g/l DWB, respectively. For the rest of strains these chrome concentrations are toxical and the concentration of 100 mg/l of Cr6+ is the bordering threshold for them. Under periodical cultivation in the medium with 30 mg/l of Cr6+ one can observe the delay of cultures growth displayed in the increase of the lag-phase and exponential growth phase as well as the decrease of medium pH (to 2). The resistance of the studied yeast to high concentrations of Cr6+ correlates with their sorptional activity.","[Effect of chromium (VI) on growth physiology and sorptional capacity of yeast] Abs: Resistance of 7 yeast species (7 strains) to various chrome concentrations in the medium and their sorptional activity have been studied. It is shown that the biomass of the yeast Williopsis californica UKM-248, Candida krusei UKM-61t under their concentration in the medium of 200 and 500 mg/l of Cr6+ is 0.74 and 0.45 g/l DWB, respectively. For the rest of strains these chrome concentrations are toxical and the concentration of 100 mg/l of Cr6+ is the bordering threshold for them. Under periodical cultivation in the medium with 30 mg/l of Cr6+ one can observe the delay of cultures growth displayed in the increase of the lag-phase and exponential growth phase as well as the decrease of medium pH (to 2). The resistance of the studied yeast to high concentrations of Cr6+ correlates with their sorptional activity."
1576780,Liu et al. 1994,Pilot study on the industrialized production of chrome pig iron smelted from a sintered chrome slag ore,"BIOSIS COPYRIGHT: BIOL ABS. A pilot study on the industrialized production of chrome pig iron was carried out in a small-sized blast furnace of 30m3 by using a sintered ore of chrome slag as flux. Cr (VI) in chrome slag was reduced at a rate of near 100% and more than 94% of total chromium were reduced metallizationally. The consumption of slag per tonne of product iron was 2.298t on average with the maximum of 2.785t. For smelting a chrome pig iron containing, more than 10% Cr, it was necessary to simultaneously add chromite in order to increase the level of chromium. By keeping the furnace temperature at over 480K, controlling the alkalinity at a lower level and adding the subsidiary burden to reduce the melting point of furnace slag, the mobility of furnace slag was significantly improved that resulted in the successful separation of iron from slag. The secondary pollution during the pilot study was monitored and it was found that it was necessary to control the dispersion of blast furnace gas","Pilot study on the industrialized production of chrome pig iron smelted from a sintered chrome slag ore Abs: BIOSIS COPYRIGHT: BIOL ABS. A pilot study on the industrialized production of chrome pig iron was carried out in a small-sized blast furnace of 30m3 by using a sintered ore of chrome slag as flux. Cr (VI) in chrome slag was reduced at a rate of near 100% and more than 94% of total chromium were reduced metallizationally. The consumption of slag per tonne of product iron was 2.298t on average with the maximum of 2.785t. For smelting a chrome pig iron containing, more than 10% Cr, it was necessary to simultaneously add chromite in order to increase the level of chromium. By keeping the furnace temperature at over 480K, controlling the alkalinity at a lower level and adding the subsidiary burden to reduce the melting point of furnace slag, the mobility of furnace slag was significantly improved that resulted in the successful separation of iron from slag. The secondary pollution during the pilot study was monitored and it was found that it was necessary to control the dispersion of blast furnace gas"
1576779,Li and  Et 1995,Spectrophotometric determination of trace chromium in water samples with sym-diphenylcarbazone,"BIOSIS COPYRIGHT: BIOL ABS. Chromium (VI) was reacted with sym-diphenyl-carbazone to form a red complex in the presence of sodium dodecylbenzenesulfonate and 0.15 mol of H2SO4. The complex had a maximum absorbance at 560 nm with a molar absorptivity of 9.74e of 0-10 mug of Cr (VI) in 25 ml solution. The common metal ions were able to be separated and concentrated by amberlite 717, giving a better selectivity. The method has been applied to determining chromium in water samples with satisfactory results.","Spectrophotometric determination of trace chromium in water samples with sym-diphenylcarbazone Abs: BIOSIS COPYRIGHT: BIOL ABS. Chromium (VI) was reacted with sym-diphenyl-carbazone to form a red complex in the presence of sodium dodecylbenzenesulfonate and 0.15 mol of H2SO4. The complex had a maximum absorbance at 560 nm with a molar absorptivity of 9.74e of 0-10 mug of Cr (VI) in 25 ml solution. The common metal ions were able to be separated and concentrated by amberlite 717, giving a better selectivity. The method has been applied to determining chromium in water samples with satisfactory results."
1576778,Lin et al. 2008,[Study on spectrum of solvent extraction of chromium( VI) by primary amine],"The Cr(VI) solvent extraction in near neutral aqueous solution by primary amine was experimentally studied by the inductively couple plasma-atomic emission spectrometry (ICP-AES), laser Raman spectroscopy, Fourier transform infrared spectroscopy (FTIR) and 1H nuclear magnetic resonance spectroscopy (1H NMR). The ICP-AES analysis of the aqueous phase before and after solvent extraction showed that primary amine could extract Cr(VI) from nearly neutral solution. Laser Raman spectroscopy of loaded organic phase showed that a new peak appeared at 890 cm(-1) after Cr(VI) was extracted by primary amine. FTIR showed the process that primary amine extracted Cr(VI) from nearly neutral aqueous solutions was different from anion exchange mechanism, and the Cr(VI) extracted into the organic phase resulted in the appearance of the peak at 885 cm(-1) of FTIR which justified that the peak at 890 cm(-1) of Raman was caused by Cr(VI). The 1H NMR spectroscopy showed that the value of chemical shift of protons of -NH2 decreased after extraction, and it is believed that primary amine was associated with Cr(VI) through hydrogen bonding. On the basis of the spectroscopic analysis results above, the mechanism of Cr(VI) extraction by primary amine from nearly neutral aqueous solutions was believed to be solvation with molecular association between primary amine and Cr(VI) through hydrogen bonding.","[Study on spectrum of solvent extraction of chromium( VI) by primary amine] Abs: The Cr(VI) solvent extraction in near neutral aqueous solution by primary amine was experimentally studied by the inductively couple plasma-atomic emission spectrometry (ICP-AES), laser Raman spectroscopy, Fourier transform infrared spectroscopy (FTIR) and 1H nuclear magnetic resonance spectroscopy (1H NMR). The ICP-AES analysis of the aqueous phase before and after solvent extraction showed that primary amine could extract Cr(VI) from nearly neutral solution. Laser Raman spectroscopy of loaded organic phase showed that a new peak appeared at 890 cm(-1) after Cr(VI) was extracted by primary amine. FTIR showed the process that primary amine extracted Cr(VI) from nearly neutral aqueous solutions was different from anion exchange mechanism, and the Cr(VI) extracted into the organic phase resulted in the appearance of the peak at 885 cm(-1) of FTIR which justified that the peak at 890 cm(-1) of Raman was caused by Cr(VI). The 1H NMR spectroscopy showed that the value of chemical shift of protons of -NH2 decreased after extraction, and it is believed that primary amine was associated with Cr(VI) through hydrogen bonding. On the basis of the spectroscopic analysis results above, the mechanism of Cr(VI) extraction by primary amine from nearly neutral aqueous solutions was believed to be solvation with molecular association between primary amine and Cr(VI) through hydrogen bonding."
1576777,Lin et al. 2007,[Determination of trace chromium(VI) by catalytic spectrofluorimetry using pyronine Y-H2O2-Cr(VI) system],"A simple and highly sensitive new kinetic catalytic fluorimetric method was proposed for the determination of trace chromium (VI), based on the catalytic effect of trace amounts of chromium (VI) on the oxidation of Pyronine Y by hydrogen peroxide in acetic acid-sodium acetate buffer medium leading to a decrease in the fluorescence intensity. The optimum conditions and kinetic properties of the catalytic reaction were also studied. The apparent activation energy and the apparent rate constant are 159. 92 k * x mol(-1) and 5. 7X10-2 s-1 respectively. The linear range of the calibration curve is 0. 02-0. 24 microg x mL(-1) and the detection limit is 0. 012 microg x mL(-1). The present method was applied to the determination of chromium(VI) in river water, and industrial and electroplating waste water with good results.","[Determination of trace chromium(VI) by catalytic spectrofluorimetry using pyronine Y-H2O2-Cr(VI) system] Abs: A simple and highly sensitive new kinetic catalytic fluorimetric method was proposed for the determination of trace chromium (VI), based on the catalytic effect of trace amounts of chromium (VI) on the oxidation of Pyronine Y by hydrogen peroxide in acetic acid-sodium acetate buffer medium leading to a decrease in the fluorescence intensity. The optimum conditions and kinetic properties of the catalytic reaction were also studied. The apparent activation energy and the apparent rate constant are 159. 92 k * x mol(-1) and 5. 7X10-2 s-1 respectively. The linear range of the calibration curve is 0. 02-0. 24 microg x mL(-1) and the detection limit is 0. 012 microg x mL(-1). The present method was applied to the determination of chromium(VI) in river water, and industrial and electroplating waste water with good results."
1576776,Li et al. 1989,[Urine-Cr assay with diphenylcarbazide],"Systemic investigations of chromium determination in urine with diphenylcarbazide were carried out and suitable analytic conditions for the determination established. Urine samples were first digested with nitric acid-hydrogen peroxide and then the chromium in the sample was oxidized to the hexavalent state by permanganate in acidic medium. After the excess oxidizing reagent was destroyed with sodium nitrite, chromium (VI) combined with diphenylcarbazide, forming a stable red color. The average recovery was 101.1%, ranging from 82.0% to 115.8%. Coefficients of variation were in the range from 2.0% to 8.4%. The method can be conveniently applied to the analysis of trace chromium in urine samples with satisfactory sensitivity and recovery. The method was applied to the measurement of 180 normal and 124 CHD (coronary heart disease) urine samples from Chengdu city. The mean of chromium level in normal urine was 6.1 micrograms/L and the range with 95% confidence of urine chromium was determined as 1.7-11 micrograms/L. The mean of chromium level in CHD urine samples was 4.2 micrograms/L. By statistical analysis, there was a significant difference between the means of the two groups (t' = 6.9, P less than 0.05).","[Urine-Cr assay with diphenylcarbazide] Abs: Systemic investigations of chromium determination in urine with diphenylcarbazide were carried out and suitable analytic conditions for the determination established. Urine samples were first digested with nitric acid-hydrogen peroxide and then the chromium in the sample was oxidized to the hexavalent state by permanganate in acidic medium. After the excess oxidizing reagent was destroyed with sodium nitrite, chromium (VI) combined with diphenylcarbazide, forming a stable red color. The average recovery was 101.1%, ranging from 82.0% to 115.8%. Coefficients of variation were in the range from 2.0% to 8.4%. The method can be conveniently applied to the analysis of trace chromium in urine samples with satisfactory sensitivity and recovery. The method was applied to the measurement of 180 normal and 124 CHD (coronary heart disease) urine samples from Chengdu city. The mean of chromium level in normal urine was 6.1 micrograms/L and the range with 95% confidence of urine chromium was determined as 1.7-11 micrograms/L. The mean of chromium level in CHD urine samples was 4.2 micrograms/L. By statistical analysis, there was a significant difference between the means of the two groups (t' = 6.9, P less than 0.05)."
1576775,Li et al. 2007,[Separation and determination methods for hexavalent chromium in working places],,[Separation and determination methods for hexavalent chromium in working places] Abs: 
1576774,Lezhnin et al. 1999,Effects of radon on the development of malignant lung neoplasms in the residents of the Sverdlovsk region,BIOSIS COPYRIGHT: BIOL ABS. RRM RESEARCH ARTICLE HUMAN RADON CARCINOGEN POLLUTANT ONCOLOGY LUNG NEOPLASM EPIDEMIOLOGY PULMONARY MEDICINE RADIATION BIOLOGY THORON TOXICITY BENZ(A)PYRENE HEXAVALENT CHROMIUM RESPIRATORY SYSTEM DISEASE MALIGNANT NEOPLASTIC DISEASE SVERDLOVSK RUSSIA,Effects of radon on the development of malignant lung neoplasms in the residents of the Sverdlovsk region Abs: BIOSIS COPYRIGHT: BIOL ABS. RRM RESEARCH ARTICLE HUMAN RADON CARCINOGEN POLLUTANT ONCOLOGY LUNG NEOPLASM EPIDEMIOLOGY PULMONARY MEDICINE RADIATION BIOLOGY THORON TOXICITY BENZ(A)PYRENE HEXAVALENT CHROMIUM RESPIRATORY SYSTEM DISEASE MALIGNANT NEOPLASTIC DISEASE SVERDLOVSK RUSSIA
1576773,Leshchinskaya and  Linnik 1990,Stability of chromium(VI) in nonmarine surface waters,BIOSIS COPYRIGHT: BIOL ABS. Possibility of Cr (VI) existence in the surface waters and sludge solutions and conditions of its reduction to Cr (III) in the presence of different organic and inogranic substances have been studied.,Stability of chromium(VI) in nonmarine surface waters Abs: BIOSIS COPYRIGHT: BIOL ABS. Possibility of Cr (VI) existence in the surface waters and sludge solutions and conditions of its reduction to Cr (III) in the presence of different organic and inogranic substances have been studied.
1576772,Lan et al. 1998,The effect of several kinds of poisonous substances on the length of oogone,"BIOSIS COPYRIGHT: BIOL ABS. In was reported the oogone length of C. braunii and C. vulgaris had changed greatly compared with the contrast group after chara braunii and chara vulgaris Vail exl were treated by trace elements: Cd2+, Hg2+, Cu6+ and pesticide: Dikushuang in the condition of simulated nature. It was fully proved that the oogone length of same species of C. would chang in the different ecological environment. Therefore, it isn't proper to differentiate the species, variety, subspecies and variant only according to the length of oogone.","The effect of several kinds of poisonous substances on the length of oogone Abs: BIOSIS COPYRIGHT: BIOL ABS. In was reported the oogone length of C. braunii and C. vulgaris had changed greatly compared with the contrast group after chara braunii and chara vulgaris Vail exl were treated by trace elements: Cd2+, Hg2+, Cu6+ and pesticide: Dikushuang in the condition of simulated nature. It was fully proved that the oogone length of same species of C. would chang in the different ecological environment. Therefore, it isn't proper to differentiate the species, variety, subspecies and variant only according to the length of oogone."
1576771,Kvasnikov et al. 1988,RESISTANCE OF PSEUDOMONAS BACTERIA TO COMPOUNDS OF HEXAVALENT CHROMIUM AND THEIR ABILITY TO REDUCE IT,BIOSIS COPYRIGHT: BIOL ABS. RRM DENITRIFICATION POLLUTION,RESISTANCE OF PSEUDOMONAS BACTERIA TO COMPOUNDS OF HEXAVALENT CHROMIUM AND THEIR ABILITY TO REDUCE IT Abs: BIOSIS COPYRIGHT: BIOL ABS. RRM DENITRIFICATION POLLUTION
1576770,Krauze and  Popov 1986,HYGIENIC ASSESSMENT OF MEASURES FOR DUST AND TOXIC SUBSTANCES CONTROL IN THE CONSTRUCTION INDUSTRY OF EAST GERMANY,BIOSIS COPYRIGHT: BIOL ABS. RRM HUMAN CHROMIUM-VI MINERAL OIL LUBRICANT DERMATITIS RESPIRATOR,HYGIENIC ASSESSMENT OF MEASURES FOR DUST AND TOXIC SUBSTANCES CONTROL IN THE CONSTRUCTION INDUSTRY OF EAST GERMANY Abs: BIOSIS COPYRIGHT: BIOL ABS. RRM HUMAN CHROMIUM-VI MINERAL OIL LUBRICANT DERMATITIS RESPIRATOR
1576769,Kogevinas et al. 2006,[Carex-Esp - Information system on occupational exposure to carcinogens in Spain in 2004],"CAREX consists of an international information system on occupational exposure to carcinogens, while Carex-Esp is a specific application of this system to Spain. This report presents the findings of the evaluation of exposures of Spanish workers recorded in 2004 using Carex-Esp. This evaluation uses international databases, and in particular data from Finland. The most frequent exposures in Spain are to solar radiation, crystalline silica, cigarette smoke, diesel engine exhaust, wood dust, radon and radon daughters, artificial mineral fibres and hexavalent chromium compounds. Estimates show that for the year 2000, a large number of workers, corresponding to approximately 25% of the Spanish workforce, were exposed to carcinogens at the place of work.","[Carex-Esp - Information system on occupational exposure to carcinogens in Spain in 2004] Abs: CAREX consists of an international information system on occupational exposure to carcinogens, while Carex-Esp is a specific application of this system to Spain. This report presents the findings of the evaluation of exposures of Spanish workers recorded in 2004 using Carex-Esp. This evaluation uses international databases, and in particular data from Finland. The most frequent exposures in Spain are to solar radiation, crystalline silica, cigarette smoke, diesel engine exhaust, wood dust, radon and radon daughters, artificial mineral fibres and hexavalent chromium compounds. Estimates show that for the year 2000, a large number of workers, corresponding to approximately 25% of the Spanish workforce, were exposed to carcinogens at the place of work."
1576768,Kito et al. 1984,HEAVY METAL ADSORPTION BY THE COMPONENTS OF RIVER SEDIMENT,HEEP COPYRIGHT: BIOL ABS. RRM CLAY HUMIC-ACID METAL POLLUTION,HEAVY METAL ADSORPTION BY THE COMPONENTS OF RIVER SEDIMENT Abs: HEEP COPYRIGHT: BIOL ABS. RRM CLAY HUMIC-ACID METAL POLLUTION
1576767,Kiesel et al. 1988,FUNDAMENTALS FOR THE ECOLOGICAL VALUATION OF DUMP COVERS,BIOSIS COPYRIGHT: BIOL ABS. RRM INDUSTRIAL WASTE LAND REUSE SOIL CHEMISTRY SOIL POLLUTION WASTE MANAGEMENT,FUNDAMENTALS FOR THE ECOLOGICAL VALUATION OF DUMP COVERS Abs: BIOSIS COPYRIGHT: BIOL ABS. RRM INDUSTRIAL WASTE LAND REUSE SOIL CHEMISTRY SOIL POLLUTION WASTE MANAGEMENT
1576766,Jolly 2007,[Cement: guidance for improved protection],"Fresh cement is an irritant that can cause rash, skin erosion, crevasses and burns. It is also an allergen, giving rise to skin diseases known as cement dermatitis, mainly due to impurities containing hexavalent chromium. Overall, cement is believed to be responsible for 10% of occupational skin diseases. This article reviews the precautions to be taken for avoiding these diseases, essentially consisting of hygiene measures and the use of suitable work clothing and personal protective equipment. A box mentions relevant French regulations.","[Cement: guidance for improved protection] Abs: Fresh cement is an irritant that can cause rash, skin erosion, crevasses and burns. It is also an allergen, giving rise to skin diseases known as cement dermatitis, mainly due to impurities containing hexavalent chromium. Overall, cement is believed to be responsible for 10% of occupational skin diseases. This article reviews the precautions to be taken for avoiding these diseases, essentially consisting of hygiene measures and the use of suitable work clothing and personal protective equipment. A box mentions relevant French regulations."
1576765,Jiang and  Yang 1981,GERMINATION OF WINTER WHEAT 6246 AND MITOSIS OF ROOT-TIP CELLS UNDER THE EFFECTOF CHROMIUM(VI),,GERMINATION OF WINTER WHEAT 6246 AND MITOSIS OF ROOT-TIP CELLS UNDER THE EFFECTOF CHROMIUM(VI) Abs: 
1576764,Hachimi et al. 1993,Study of the hydration effect and composition of the salts on chromium cluster formation by laser ablation,"BIOSIS COPYRIGHT: BIOL ABS. Over the last 10 years interest in metal compounds present in industrial environmental fumes has been increasing because of their toxicity to the human body. Hexavalent chromium belongs to the category of toxic metals which are associated with allergic reactions and cancer. Analytical techniques of chromium stoichiometry are divided in two classes: indirect and direct methods: indirect methods (luminescence spectroscopy, atomic absorption spectrometry, ion-exchange chromatography, etc) which have the drawback that there is an uncertainty about the oxidation state of chromium when compounds are diluted in solution for analysis: direct techniques (Raman, X-ray, FT-IR, XPS, SIMS,...) have the advantage of in situ determination of chromium valency. Laser microprobe is a mass spectrometric technique coupled to laser ionization which permits in situ analysis of elements. In 1989, a methodology of determination of valency in reference chromium compounds (oxides and salts) has","Study of the hydration effect and composition of the salts on chromium cluster formation by laser ablation Abs: BIOSIS COPYRIGHT: BIOL ABS. Over the last 10 years interest in metal compounds present in industrial environmental fumes has been increasing because of their toxicity to the human body. Hexavalent chromium belongs to the category of toxic metals which are associated with allergic reactions and cancer. Analytical techniques of chromium stoichiometry are divided in two classes: indirect and direct methods: indirect methods (luminescence spectroscopy, atomic absorption spectrometry, ion-exchange chromatography, etc) which have the drawback that there is an uncertainty about the oxidation state of chromium when compounds are diluted in solution for analysis: direct techniques (Raman, X-ray, FT-IR, XPS, SIMS,...) have the advantage of in situ determination of chromium valency. Laser microprobe is a mass spectrometric technique coupled to laser ionization which permits in situ analysis of elements. In 1989, a methodology of determination of valency in reference chromium compounds (oxides and salts) has"
1576763,Gutsanu et al. 1985,EVALUATION OF FACTORS AFFECTING THE EXTRACTION OF CHROMIUM-VI FROM SOLUTIONS WITH THE AID OF ANIONITES,BIOSIS COPYRIGHT: BIOL ABS. RRM WATER POLLUTION,EVALUATION OF FACTORS AFFECTING THE EXTRACTION OF CHROMIUM-VI FROM SOLUTIONS WITH THE AID OF ANIONITES Abs: BIOSIS COPYRIGHT: BIOL ABS. RRM WATER POLLUTION
1576762,Gusenleitner and  Nimmervoll 1988,THE EFFECT OF CHROMIUM ACCUMULATION ON GROWTH OF CULTIVATED PLANTS IN A POTTED TRIAL WITH TWO DIFFERENT SOILS OF UPPER AUSTRIA,BIOSIS COPYRIGHT: BIOL ABS. RRM CROPS LOAMY SILT SOIL LOAMY SAND SOIL TOXICITY SOIL PH MINERAL FERTILIZERS,THE EFFECT OF CHROMIUM ACCUMULATION ON GROWTH OF CULTIVATED PLANTS IN A POTTED TRIAL WITH TWO DIFFERENT SOILS OF UPPER AUSTRIA Abs: BIOSIS COPYRIGHT: BIOL ABS. RRM CROPS LOAMY SILT SOIL LOAMY SAND SOIL TOXICITY SOIL PH MINERAL FERTILIZERS
1576761,Giese 1997,"Investigations of the specification of chromium in sea water, sea ice and snow in selected areas of the Arctic","BIOSIS COPYRIGHT: BIOL ABS. For the first time different chromium species were studied in sea water, sea ice and snow of the Arctic, in order to get information about their distribution in this region. The samples were taken at the German Arctic Research station (Koldewey-Station) in Ny-Alesund at Spitsbergen and during the expedition ARK X/1 with the research vessel ""RV Polarstern"". Both, the Koldewey station and the research vessel ""Polarstern"" are operated by the Alfred-Wegener-Institute, Bremerhaven. The liquid-liquid extraction followed by Atomic Absorption Spectrometry (AAS), a method for matrix separation from seawater samples, was modified for the separation of Cr(VI) and Cr(III). Contrary to other methods determining the content of total chromium and only for one species, the liquid-liquid extraction allowed for the first time an experimental determination of both species in the same sample. In contrast other methods determined the content of total chromium and only for one species. In sp","Investigations of the specification of chromium in sea water, sea ice and snow in selected areas of the Arctic Abs: BIOSIS COPYRIGHT: BIOL ABS. For the first time different chromium species were studied in sea water, sea ice and snow of the Arctic, in order to get information about their distribution in this region. The samples were taken at the German Arctic Research station (Koldewey-Station) in Ny-Alesund at Spitsbergen and during the expedition ARK X/1 with the research vessel ""RV Polarstern"". Both, the Koldewey station and the research vessel ""Polarstern"" are operated by the Alfred-Wegener-Institute, Bremerhaven. The liquid-liquid extraction followed by Atomic Absorption Spectrometry (AAS), a method for matrix separation from seawater samples, was modified for the separation of Cr(VI) and Cr(III). Contrary to other methods determining the content of total chromium and only for one species, the liquid-liquid extraction allowed for the first time an experimental determination of both species in the same sample. In contrast other methods determined the content of total chromium and only for one species. In sp"
1576760,Gabisoniya et al. 1989,Metal regeneration from electroplating technology effluents containing chromium and copper ions,BIOSIS COPYRIGHT: BIOL ABS. The data revealing optimal conditions for the regeneration of Cr (VI) and Cu (II) ions and their transition to the low-valent state under radiation treatment from electroplating effluents are presented.,Metal regeneration from electroplating technology effluents containing chromium and copper ions Abs: BIOSIS COPYRIGHT: BIOL ABS. The data revealing optimal conditions for the regeneration of Cr (VI) and Cu (II) ions and their transition to the low-valent state under radiation treatment from electroplating effluents are presented.
1576759,Fukunaga et al. 1981,GENETIC EFFECTS OF ENVIRONMENTAL POLLUTANTS ON EUKARYOTIC CELLS: MUTAGENICITY ON NUCLEAR AND MITOCHONDRIAL GENES OF YEAST BY METALS,,GENETIC EFFECTS OF ENVIRONMENTAL POLLUTANTS ON EUKARYOTIC CELLS: MUTAGENICITY ON NUCLEAR AND MITOCHONDRIAL GENES OF YEAST BY METALS Abs: 
1576758,Fu and  Et 1993,Drawing water to control ground water pollution from chromium,"BIOSIS COPYRIGHT: BIOL ABS. Taking the environmental hydrological and geological conditions of an Cr6+ polluted urban industrial area into account. A countermeasure, i.e. drawing water from underground in the center of the area to cut off underground streams, was taken to reduce the level of pollution of ground water from Cr6+. After 6 years practice, the polluted area was reduced from 0.321km2 to 0.032km2 and the drinking water supply was back to normal.","Drawing water to control ground water pollution from chromium Abs: BIOSIS COPYRIGHT: BIOL ABS. Taking the environmental hydrological and geological conditions of an Cr6+ polluted urban industrial area into account. A countermeasure, i.e. drawing water from underground in the center of the area to cut off underground streams, was taken to reduce the level of pollution of ground water from Cr6+. After 6 years practice, the polluted area was reduced from 0.321km2 to 0.032km2 and the drinking water supply was back to normal."
1576757,Fu et al. 1998,Adsorption and photocatalytic detoxification of Cr(VI) ion on TiO2,"BIOSIS COPYRIGHT: BIOL ABS. Adsorption of Cr(VI) on TiO2 decreased with the increase of the suspension pH. The largest Cr(VI) adsorption appeared when its initial concentration was about 300 mumol. The existence of H2PO4- anion and acetic acid decreased the adsorption efficiency of Cr (VI) , and formic acid promoted its adsorption efficiency. Other organic molecules had noninterference with Cr (VI) adsorption, and competitive adsorption did not happen between them. System pH had remarkable effects on photocatalytic reduction of Cr (VI) on TiO2. H2PO4 - anion and Mn2+ cation both had inhibition on Cr (VI) reduction. Different organic compounds had different influences on Cr(VI) reduction because of their different electrical properties. Under the sunlight irradiation, Cr (VI) reduction was also observed on TiO2 photocatalyst. After separation of the catalyst, chromium was removed and detoxified from the waste water by adjusting the pH of the system. TiO2 photocatalyst was reactivated and reused af","Adsorption and photocatalytic detoxification of Cr(VI) ion on TiO2 Abs: BIOSIS COPYRIGHT: BIOL ABS. Adsorption of Cr(VI) on TiO2 decreased with the increase of the suspension pH. The largest Cr(VI) adsorption appeared when its initial concentration was about 300 mumol. The existence of H2PO4- anion and acetic acid decreased the adsorption efficiency of Cr (VI) , and formic acid promoted its adsorption efficiency. Other organic molecules had noninterference with Cr (VI) adsorption, and competitive adsorption did not happen between them. System pH had remarkable effects on photocatalytic reduction of Cr (VI) on TiO2. H2PO4 - anion and Mn2+ cation both had inhibition on Cr (VI) reduction. Different organic compounds had different influences on Cr(VI) reduction because of their different electrical properties. Under the sunlight irradiation, Cr (VI) reduction was also observed on TiO2 photocatalyst. After separation of the catalyst, chromium was removed and detoxified from the waste water by adjusting the pH of the system. TiO2 photocatalyst was reactivated and reused af"
1576756,Wang and  Et 1993,Study on removing hexavalent chromium by sulfate-reducing bacteria (SRIV),"BIOSIS COPYRIGHT: BIOL ABS. A strain of sulfate-reducing bacteria capable of reducing hexavalent chromium was isolated from electroplating sludge by using Hungate anaerobic technique. The strain was a motile curved rod, possessing singly polar flagella. The cell was 0.5 - 0.8 mum in length, non-sporing, non-capsules, Gram-negative. The oxidation was incomplete, leading to acetate production; and glucose, sucrose, pyruvate, H2 + CO2, alcohol, and formate were fermented in the absence of an external electron acceptor. These characteristics established the isolate as Desulfovibrio sp. Reclaiming of hexevalent chromium with the isolate has shown that it was resistant to Cr(VI) concentrations of up to 10 and at optimum pH 7.0. And under such conditions, the optimum Cr(VI) concentration for its growth was 4val of Cr(VI) was 99.8%. SRIV strain was an engineered strain in removing Cr(VI) from wastewater.","Study on removing hexavalent chromium by sulfate-reducing bacteria (SRIV) Abs: BIOSIS COPYRIGHT: BIOL ABS. A strain of sulfate-reducing bacteria capable of reducing hexavalent chromium was isolated from electroplating sludge by using Hungate anaerobic technique. The strain was a motile curved rod, possessing singly polar flagella. The cell was 0.5 - 0.8 mum in length, non-sporing, non-capsules, Gram-negative. The oxidation was incomplete, leading to acetate production; and glucose, sucrose, pyruvate, H2 + CO2, alcohol, and formate were fermented in the absence of an external electron acceptor. These characteristics established the isolate as Desulfovibrio sp. Reclaiming of hexevalent chromium with the isolate has shown that it was resistant to Cr(VI) concentrations of up to 10 and at optimum pH 7.0. And under such conditions, the optimum Cr(VI) concentration for its growth was 4val of Cr(VI) was 99.8%. SRIV strain was an engineered strain in removing Cr(VI) from wastewater."
1576755,Eliseeva et al. 1991,Effect of different cultivation conditions on chromium-reducing activity of an associative culture of microorganisms,"BIOSIS COPYRIGHT: BIOL ABS. Effect of different factors (temperature of bacteria cultivation, concentration of activated sludge and carriers) on the process of six-valent chromium reduction by associative culture consisting of cellulose-decomposing, butyric-acid and chromium-reducing bacteria. Wheat straw is an optimal carrier for the process of chromium reduction. When using it as a carrier for the process activation it is sufficient to add 20% of activated sludge when using the maize stalk-40 %. The association being commercially used, the process of chromium reduction may be carried out at 25 ?C.","Effect of different cultivation conditions on chromium-reducing activity of an associative culture of microorganisms Abs: BIOSIS COPYRIGHT: BIOL ABS. Effect of different factors (temperature of bacteria cultivation, concentration of activated sludge and carriers) on the process of six-valent chromium reduction by associative culture consisting of cellulose-decomposing, butyric-acid and chromium-reducing bacteria. Wheat straw is an optimal carrier for the process of chromium reduction. When using it as a carrier for the process activation it is sufficient to add 20% of activated sludge when using the maize stalk-40 %. The association being commercially used, the process of chromium reduction may be carried out at 25 ?C."
1576754,Stamatiou 2012,Como hexavalente y riesgo de cáncer de vejiga,,Como hexavalente y riesgo de cáncer de vejiga Abs: 
1576753,Wang et al. 2011,[Transformation of copper and chromium in co-contaminated soil and its influence on bioavailability for pakchoi (Brassica chinensis)],"Heavy metal fractions in soil play an important role in the bioavailability for plants. A pot experiment was carried out to study the transformation and bioavailability for pakchoi of exogenetic copper and hexavalent chromium in co-contaminated soil. The results showed that one month after tested heavy metals were added into soil, the chromium was present mainly in residual and organic bonded form while copper was mainly bound to hydrated oxides of iron and manganese as well as residual form. Lower concentrations copper (&lt; or = 400 mg x kg(-1)) in soil could promote chromium transform from other forms to exchangeable form while higher concentrations copper (&gt; or = 800 mg x kg(-1)) in soil would inhibit this transformation. Similarly, chromium in low concentrations (&lt; or = 5 mg x kg(-1)) could facility copper transform to residual form while chromium in high concentrations (&gt; or = 20 mg x kg(-1)) would reduce such transformation process. Both added chromium to soil polluted by high concentrations copper and added copper to high chromium content soil could promote the polluted soil reach quasi-equilibrium state. Additionally, adding copper in soil could inhibit chromium uptake of pakchoi by promoting soil OM-Cr transformed into RES-Cr. While adding chromium in soil could reduce copper uptake of pakchoi by stimulating the EXE-Cu transformed into the RES-Cu. Therefore, it is necessary to take into consideration the synthetic effects of copper and chromium when carrying on assessment and phytoremediation to co-contaminated soil.","[Transformation of copper and chromium in co-contaminated soil and its influence on bioavailability for pakchoi (Brassica chinensis)] Abs: Heavy metal fractions in soil play an important role in the bioavailability for plants. A pot experiment was carried out to study the transformation and bioavailability for pakchoi of exogenetic copper and hexavalent chromium in co-contaminated soil. The results showed that one month after tested heavy metals were added into soil, the chromium was present mainly in residual and organic bonded form while copper was mainly bound to hydrated oxides of iron and manganese as well as residual form. Lower concentrations copper (&lt; or = 400 mg x kg(-1)) in soil could promote chromium transform from other forms to exchangeable form while higher concentrations copper (&gt; or = 800 mg x kg(-1)) in soil would inhibit this transformation. Similarly, chromium in low concentrations (&lt; or = 5 mg x kg(-1)) could facility copper transform to residual form while chromium in high concentrations (&gt; or = 20 mg x kg(-1)) would reduce such transformation process. Both added chromium to soil polluted by high concentrations copper and added copper to high chromium content soil could promote the polluted soil reach quasi-equilibrium state. Additionally, adding copper in soil could inhibit chromium uptake of pakchoi by promoting soil OM-Cr transformed into RES-Cr. While adding chromium in soil could reduce copper uptake of pakchoi by stimulating the EXE-Cu transformed into the RES-Cu. Therefore, it is necessary to take into consideration the synthetic effects of copper and chromium when carrying on assessment and phytoremediation to co-contaminated soil."
1576752,Vega-Villasante et al. 2013,"[Evaluation of Psilocybe cubensis (Agaricales, Basidiomycota) toxicity over Artemia franciscana (Crustacea, Anostraca)]","<strong>BACKGROUND: </strong>Psilocybe cubensis is a species with psychodysleptic action that grows on cattle dung in pastures in the tropics and subtropics. This fungus has been widely used in Mexico since ancient times both for ceremonies and rituals, as well as for healing or medicinal purposes. Artemia franciscana is a crustacean frequently used as a model organism for toxicity testing.<br /><br /><strong>AIMS: </strong>With the objective of determining the toxicity of P. cubensis, the results of a study with the extract of P. cubensis on nauplii and adults of the brine shrimp A. franciscana are presented.<br /><br /><strong>METHODS: </strong>Specimens were collected at Bahía de Banderas, Jalisco, Mexico, and were dried and homogenized in artificial sea water. Bioassays were carried out on crystal vials filled with different concentrations of the extract of P. cubensis (EAP), and with potassium dichromate as reference toxic compound. The median lethal concentration (LC(50)) in nauplii and adults and the inhibition of cysts hatching in A. franciscana were calculated.<br /><br /><strong>RESULTS: </strong>Nauplii showed a LC(50) = 135 ?g/ml, while adults a LC(50) = 172 ?g/ml. Cysts' hatching was inhibited by the EAP at all tested concentrations.<br /><br /><strong>CONCLUSIONS: </strong>Under the conditions of this study, the extract of P. cubensis was toxic for nauplii and adults of A. franciscana.","[Evaluation of Psilocybe cubensis (Agaricales, Basidiomycota) toxicity over Artemia franciscana (Crustacea, Anostraca)] Abs: <strong>BACKGROUND: </strong>Psilocybe cubensis is a species with psychodysleptic action that grows on cattle dung in pastures in the tropics and subtropics. This fungus has been widely used in Mexico since ancient times both for ceremonies and rituals, as well as for healing or medicinal purposes. Artemia franciscana is a crustacean frequently used as a model organism for toxicity testing.<br /><br /><strong>AIMS: </strong>With the objective of determining the toxicity of P. cubensis, the results of a study with the extract of P. cubensis on nauplii and adults of the brine shrimp A. franciscana are presented.<br /><br /><strong>METHODS: </strong>Specimens were collected at Bahía de Banderas, Jalisco, Mexico, and were dried and homogenized in artificial sea water. Bioassays were carried out on crystal vials filled with different concentrations of the extract of P. cubensis (EAP), and with potassium dichromate as reference toxic compound. The median lethal concentration (LC(50)) in nauplii and adults and the inhibition of cysts hatching in A. franciscana were calculated.<br /><br /><strong>RESULTS: </strong>Nauplii showed a LC(50) = 135 ?g/ml, while adults a LC(50) = 172 ?g/ml. Cysts' hatching was inhibited by the EAP at all tested concentrations.<br /><br /><strong>CONCLUSIONS: </strong>Under the conditions of this study, the extract of P. cubensis was toxic for nauplii and adults of A. franciscana."
1576751,Yu et al. 2012,[Simultaneous determination of trivalent chromium and hexavalent chromium in plastics by accelerated solvent extraction-ion chromatography],"A method based on accelerated solvent extraction-ion chromatography (ASE-IC) was developed for the simultaneous determination of trivalent chromium (Cr(III)) and hexavalent chromium (Cr(VI)) in plastic samples. The accelerated solvent extraction was employed as the pretreatment method for the simultaneous extraction of the Cr(III) and Cr(VI) from the samples. Cr(III) and Cr(VI) were derivatized with 2,6-pyridinedicarboxylic acid (PDCA) and 1,5-diphenyl-carbazide (DPC), and detected by an ultraviolet-visible (UV-Vis) detector at UV and visible wavelengths, respectively. The results showed that the limits of detection for Cr(III) and Cr(VI) were 5.0 microg/L and 0.5 microg/L and the good linearities of the calibration curves for them were in the ranges of 50 - 1 000 microg/L (r2 = 0.9994) and 5.0 - 100 microg/L (r2 = 0.9998), respectively. The recoveries were between 90.7% and 101.1% with the relative standard deviations (RSDs) of 1.7% -4.4% for Cr(III) and Cr(VI). The method is sensitive, reproducible and adaptable to the simultaneous determination of Cr(III) and Cr(VI) in the plastic samples.","[Simultaneous determination of trivalent chromium and hexavalent chromium in plastics by accelerated solvent extraction-ion chromatography] Abs: A method based on accelerated solvent extraction-ion chromatography (ASE-IC) was developed for the simultaneous determination of trivalent chromium (Cr(III)) and hexavalent chromium (Cr(VI)) in plastic samples. The accelerated solvent extraction was employed as the pretreatment method for the simultaneous extraction of the Cr(III) and Cr(VI) from the samples. Cr(III) and Cr(VI) were derivatized with 2,6-pyridinedicarboxylic acid (PDCA) and 1,5-diphenyl-carbazide (DPC), and detected by an ultraviolet-visible (UV-Vis) detector at UV and visible wavelengths, respectively. The results showed that the limits of detection for Cr(III) and Cr(VI) were 5.0 microg/L and 0.5 microg/L and the good linearities of the calibration curves for them were in the ranges of 50 - 1 000 microg/L (r2 = 0.9994) and 5.0 - 100 microg/L (r2 = 0.9998), respectively. The recoveries were between 90.7% and 101.1% with the relative standard deviations (RSDs) of 1.7% -4.4% for Cr(III) and Cr(VI). The method is sensitive, reproducible and adaptable to the simultaneous determination of Cr(III) and Cr(VI) in the plastic samples."
1576750,Zhang et al. 2012,[Chronic exposure to trace chromium induces oxidative stress in mouse liver cells],"<strong>OBJECTIVE: </strong>To explore the effects of chronic exposure to trace chromium (VI) as a result of metal-on-metal hip arthroplasty on oxidative stress in mouse liver cells.<br /><br /><strong>METHODS: </strong>Eighty NIH mice were randomly divided into 4 groups and subject to intraperitoneal injection of CrO(3) at the dose of 0, 5, 10 or 20 mg/kg every other day for 16 weeks. Five mice from each group were selected every 4 weeks for determining the content of chromium (VI) in the whole blood and the levels of reactive oxygen species (ROS), malondialdehyde (MDA), eglutathione (GSH), glutathione reductase (GR) activity, and glutamate cysteine ligase (GCL) expression in the liver cells. The ultrastructural changes of the liver cells were also observed using transmission electron microscopy.<br /><br /><strong>RESULTS: </strong>Exposure to 5 and 10 mg/kg CrO(3) caused significantly increased blood chromium concentration and ROS level, which reached the peak level at 8 weeks and became stabilized, whereas at the dose of 20 mg/kg, CrO(3) exposure resulted in progressive, time-dependent increase of blood chromium concentration and ROS level. MDA showed no significant changes in the 4 groups. With the prolongation of the exposure time, GSH content and GR activity were decreased in these groups. In 5 and 10 mg/kg CrO(3) groups, GCL expression increased at each time point of measurement, but in 20 mg/kg group, GCL expression decreased gradually with a prolonged exposure. Transmission electron microscopy revealed apoptotic changes of the liver cells in 20 mg/kg group.<br /><br /><strong>CONCLUSION: </strong>The slow accumulation of trace chromium (VI) after metal-on-metal hip arthroplasty may cause oxidative stress and changes in the oxidative stress system in the liver cells.","[Chronic exposure to trace chromium induces oxidative stress in mouse liver cells] Abs: <strong>OBJECTIVE: </strong>To explore the effects of chronic exposure to trace chromium (VI) as a result of metal-on-metal hip arthroplasty on oxidative stress in mouse liver cells.<br /><br /><strong>METHODS: </strong>Eighty NIH mice were randomly divided into 4 groups and subject to intraperitoneal injection of CrO(3) at the dose of 0, 5, 10 or 20 mg/kg every other day for 16 weeks. Five mice from each group were selected every 4 weeks for determining the content of chromium (VI) in the whole blood and the levels of reactive oxygen species (ROS), malondialdehyde (MDA), eglutathione (GSH), glutathione reductase (GR) activity, and glutamate cysteine ligase (GCL) expression in the liver cells. The ultrastructural changes of the liver cells were also observed using transmission electron microscopy.<br /><br /><strong>RESULTS: </strong>Exposure to 5 and 10 mg/kg CrO(3) caused significantly increased blood chromium concentration and ROS level, which reached the peak level at 8 weeks and became stabilized, whereas at the dose of 20 mg/kg, CrO(3) exposure resulted in progressive, time-dependent increase of blood chromium concentration and ROS level. MDA showed no significant changes in the 4 groups. With the prolongation of the exposure time, GSH content and GR activity were decreased in these groups. In 5 and 10 mg/kg CrO(3) groups, GCL expression increased at each time point of measurement, but in 20 mg/kg group, GCL expression decreased gradually with a prolonged exposure. Transmission electron microscopy revealed apoptotic changes of the liver cells in 20 mg/kg group.<br /><br /><strong>CONCLUSION: </strong>The slow accumulation of trace chromium (VI) after metal-on-metal hip arthroplasty may cause oxidative stress and changes in the oxidative stress system in the liver cells."
1576749,Zhang et al. 2012,[Hexavalent chromium pollution and exposure level in electroplating workplace],"<strong>OBJECTIVE: </strong>To investigate the pollution of hexavalent chromium in the electroplating workplace and screen the biomarkers of chromium exposure.<br /><br /><strong>MATERIAL: </strong>Field occupational health investigation was conducted in 25 electroplating workplaces. 157 electroplating workers and 93 healthy unexposed controls were recruited. The epidemiological information was collected with face to face interview. Chromium in erythrocytes was determined by graphite furnace atomic absorption spectrophotometer.<br /><br /><strong>RESULTS: </strong>The median of short-term exposure concentration of chromium in the air at electroplating workplace was 0.06 mg/m(3) (median) and ranging from 0.01 (detect limit) to 0.53 mg/m(3)). The median concentration of Cr (VI) in erythrocytes in electroplating workers was 4.41 (2.50 ? 5.29) µg/L, which was significantly higher than that in control subjects [1.54 (0.61 ? 2.98) µg/L, P &lt; 0.01]. After stratified by potential confounding factors such as gender, age, smoking status and alcohol consumption, significant differences still existed between electroplating workers and control subjects, except for the subjects of age less than 30 years old (P = 0.11).<br /><br /><strong>CONCLUSION: </strong>There was hexavalent chromium pollution in electroplating workplace. Occupational hazards prevention measures should be taken to control the chromium pollution hazards.","[Hexavalent chromium pollution and exposure level in electroplating workplace] Abs: <strong>OBJECTIVE: </strong>To investigate the pollution of hexavalent chromium in the electroplating workplace and screen the biomarkers of chromium exposure.<br /><br /><strong>MATERIAL: </strong>Field occupational health investigation was conducted in 25 electroplating workplaces. 157 electroplating workers and 93 healthy unexposed controls were recruited. The epidemiological information was collected with face to face interview. Chromium in erythrocytes was determined by graphite furnace atomic absorption spectrophotometer.<br /><br /><strong>RESULTS: </strong>The median of short-term exposure concentration of chromium in the air at electroplating workplace was 0.06 mg/m(3) (median) and ranging from 0.01 (detect limit) to 0.53 mg/m(3)). The median concentration of Cr (VI) in erythrocytes in electroplating workers was 4.41 (2.50 ? 5.29) µg/L, which was significantly higher than that in control subjects [1.54 (0.61 ? 2.98) µg/L, P &lt; 0.01]. After stratified by potential confounding factors such as gender, age, smoking status and alcohol consumption, significant differences still existed between electroplating workers and control subjects, except for the subjects of age less than 30 years old (P = 0.11).<br /><br /><strong>CONCLUSION: </strong>There was hexavalent chromium pollution in electroplating workplace. Occupational hazards prevention measures should be taken to control the chromium pollution hazards."
1576748,Li et al. 2012,[Effect of hOGG1 gene on the oxidative damage of mitochondrial DNA induced by hexavalent chromium],"<strong>OBJECTIVE: </strong>To explore the effect of hOGG1 gene on the repair capability of oxidative damage in mitochondrial DNA induced by hexavalent chromium (Cr (VI)).<br /><br /><strong>METHODS: </strong>After incubating with Cr(VI) at the concentrations of 2, 8, 32 micromol/L for 24 hours, mitochondria from L-02 hepatocytes were collected. Cellular ROS and hOGG1 mRNA and mitochondrial 8-OHdG and hOGG1 protein in L-02 hepatocytes were examined by Fluorometric Assay Kit, RT-qPCR, 8-OHdG ELISA Kit and western blot respectively.<br /><br /><strong>RESULTS: </strong>Compared with the control group, the levels of cellular ROS and mitochondrial 8-OHdG in 8 and 32 micromol/L Cr(VI) treated groups were significantly increased (P &lt; 0.05). The levels of cellular hOGG1 mRNA and mitochondrial hOGG1 protein in 2 micromol/L Cr (VI) treated group were increased significantly (P &lt; 0.05), but decreased in 32 micromol/l. group (P &lt; 0.05).<br /><br /><strong>CONCLUSION: </strong>Overproduction of cellular ROS could be induced by Cr (VI) and could result in genomic DNA oxidative damage, and the lower expression of cellular hOGG1 gene could decrease the repair capability of mitochondrial DNA. Therefore, the cellular hOGG1 gene exerted important effect in the repair of mitochondrial DNA oxidative damage induced by Cr( VI).","[Effect of hOGG1 gene on the oxidative damage of mitochondrial DNA induced by hexavalent chromium] Abs: <strong>OBJECTIVE: </strong>To explore the effect of hOGG1 gene on the repair capability of oxidative damage in mitochondrial DNA induced by hexavalent chromium (Cr (VI)).<br /><br /><strong>METHODS: </strong>After incubating with Cr(VI) at the concentrations of 2, 8, 32 micromol/L for 24 hours, mitochondria from L-02 hepatocytes were collected. Cellular ROS and hOGG1 mRNA and mitochondrial 8-OHdG and hOGG1 protein in L-02 hepatocytes were examined by Fluorometric Assay Kit, RT-qPCR, 8-OHdG ELISA Kit and western blot respectively.<br /><br /><strong>RESULTS: </strong>Compared with the control group, the levels of cellular ROS and mitochondrial 8-OHdG in 8 and 32 micromol/L Cr(VI) treated groups were significantly increased (P &lt; 0.05). The levels of cellular hOGG1 mRNA and mitochondrial hOGG1 protein in 2 micromol/L Cr (VI) treated group were increased significantly (P &lt; 0.05), but decreased in 32 micromol/l. group (P &lt; 0.05).<br /><br /><strong>CONCLUSION: </strong>Overproduction of cellular ROS could be induced by Cr (VI) and could result in genomic DNA oxidative damage, and the lower expression of cellular hOGG1 gene could decrease the repair capability of mitochondrial DNA. Therefore, the cellular hOGG1 gene exerted important effect in the repair of mitochondrial DNA oxidative damage induced by Cr( VI)."
1576747,Yang et al. 2012,[Interference of hexavalent chromium on VDAC1 mRNA expression or ATP level and their potential association],"<strong>OBJECTIVE: </strong>To explore the interference of hexavalent chromium-Cr(VI) on voltage-dependent anion channel (VDAC1) mRNA expression and intracellular adenosine triphosphate (ATP) level in cells and their potential association.<br /><br /><strong>METHODS: </strong>Cultured L-02 hepatocytes were treated with 2, 4, 8, 16 and 32 micromol/L of Cr(VI) for 12, 24 and 36 hours (h). The expression of VDAC1 mRNA was measured by reverse transcription quantitative polymerase chain reaction (RT-qPCR), whereas the levels of intracellular ATP was determined by an ATP-specific bioluminescence assay.<br /><br /><strong>RESULTS: </strong>(1) The expression of VDAC1 mRNA in cells of treated groups was less than that of control group at 12h, and then showed slight increase at 24h, and increased significantly after 36 h of treatment. (2) After being treated by Cr(VI) for 12 h, ATP level in cells increased, especially in higher dose groups, and the ATP level then decreased significantly at 24h except in the lowest dosage (2 micromol/L) group, and increased again at 36h in 2 micromol/L and 4 micromol/L groups, but the ATP level in 8, 16 and 32 micromol/L groups remained less than that in the control group. (3) Correlation analysis showed a moderate negative relationship between VDAC1 mRNA expression and intracellular ATP level during Cr (VI) treatment (r = -0.604, P &lt; 0.05).<br /><br /><strong>CONCLUSION: </strong>The interference of Cr(VI) on ATP level was associated with abnormal expression of VDAC1 mRNA, over-expression of VDAC1 mRNA may be one of molecular mechanisms for the decrease of ATP level induced by heavy metal-Cr(VI).","[Interference of hexavalent chromium on VDAC1 mRNA expression or ATP level and their potential association] Abs: <strong>OBJECTIVE: </strong>To explore the interference of hexavalent chromium-Cr(VI) on voltage-dependent anion channel (VDAC1) mRNA expression and intracellular adenosine triphosphate (ATP) level in cells and their potential association.<br /><br /><strong>METHODS: </strong>Cultured L-02 hepatocytes were treated with 2, 4, 8, 16 and 32 micromol/L of Cr(VI) for 12, 24 and 36 hours (h). The expression of VDAC1 mRNA was measured by reverse transcription quantitative polymerase chain reaction (RT-qPCR), whereas the levels of intracellular ATP was determined by an ATP-specific bioluminescence assay.<br /><br /><strong>RESULTS: </strong>(1) The expression of VDAC1 mRNA in cells of treated groups was less than that of control group at 12h, and then showed slight increase at 24h, and increased significantly after 36 h of treatment. (2) After being treated by Cr(VI) for 12 h, ATP level in cells increased, especially in higher dose groups, and the ATP level then decreased significantly at 24h except in the lowest dosage (2 micromol/L) group, and increased again at 36h in 2 micromol/L and 4 micromol/L groups, but the ATP level in 8, 16 and 32 micromol/L groups remained less than that in the control group. (3) Correlation analysis showed a moderate negative relationship between VDAC1 mRNA expression and intracellular ATP level during Cr (VI) treatment (r = -0.604, P &lt; 0.05).<br /><br /><strong>CONCLUSION: </strong>The interference of Cr(VI) on ATP level was associated with abnormal expression of VDAC1 mRNA, over-expression of VDAC1 mRNA may be one of molecular mechanisms for the decrease of ATP level induced by heavy metal-Cr(VI)."
1576746,Zinalieva et al. 2012,[The study of corrective role of plant--based drugs with antioxidant action in experimental intoxication with potassium dichromate],"The disturbance of the structure and function of pulmonary surfactant system (pSS) is an essential component of almost all pulmonary diseases. Chromium compounds have a damaging effect on the PSS, which contributes to the formation of nonspecific pulmonary diseases and a burden of chrome disease. The results showed that the oil of licorice (Glycyrrhiza glabra L) protects PSS in chronic chrome intoxication.","[The study of corrective role of plant--based drugs with antioxidant action in experimental intoxication with potassium dichromate] Abs: The disturbance of the structure and function of pulmonary surfactant system (pSS) is an essential component of almost all pulmonary diseases. Chromium compounds have a damaging effect on the PSS, which contributes to the formation of nonspecific pulmonary diseases and a burden of chrome disease. The results showed that the oil of licorice (Glycyrrhiza glabra L) protects PSS in chronic chrome intoxication."
1576745,Mutti et al. 2012,[New perspectives in biomonitoring of metallic elements: the example of hexavalent chromium],"Plating industry is an important productive sector in all the national territory, because of its contribution to a high number of industrial products and crafts. In the chrome plating sector there is a specific chemical risk due to the exposure to compounds containing hexavalent Chromium [Cr(VI)]. Exhaled breath condensate (EBC) has been used to study both acute and long term exposure to Cr(VI) in chrome plating workers. Cr-EBC correlates with specific oxidative stress biomarkers. Moreover, both total Cr and its hexavalent fraction can be measured in EBC, which therefore is a promising biological fluid to assess the absorbed dose at the target organ level, the pulmonary reduction kinetics of Cr(VI) and in general its local pneumotoxic effects. EBC collection and analysis could give additional information to the traditional measures performed during biomonitoring.","[New perspectives in biomonitoring of metallic elements: the example of hexavalent chromium] Abs: Plating industry is an important productive sector in all the national territory, because of its contribution to a high number of industrial products and crafts. In the chrome plating sector there is a specific chemical risk due to the exposure to compounds containing hexavalent Chromium [Cr(VI)]. Exhaled breath condensate (EBC) has been used to study both acute and long term exposure to Cr(VI) in chrome plating workers. Cr-EBC correlates with specific oxidative stress biomarkers. Moreover, both total Cr and its hexavalent fraction can be measured in EBC, which therefore is a promising biological fluid to assess the absorbed dose at the target organ level, the pulmonary reduction kinetics of Cr(VI) and in general its local pneumotoxic effects. EBC collection and analysis could give additional information to the traditional measures performed during biomonitoring."
1576744,De Marco et al. 1988,Death risk due to cancer of the respiratory apparatus in chromate production workers,"This is a report on the results of a retrospective cohort study aimed at assessing the risk of death due to respiratory cancer in the workers of a chromate production plant. A total of 981 subjects had been employed for varying periods between 1948 and 1985. The study covered workers with more than 1yr of cumulative exposure, for whom the risk period starts 10yrs after beginning of exposure (latency period). Among the eligible subjects, 20 cases of respiratory tract cancer were observed: 14 located in the lung, 3 in the pleura, and 3 in the larynx. The observed deaths were compared with expected deaths on the basis of the mortality rates for Italy. The SMR was statistically significant for tumours of the pleura (SMR = 30) and the lung (SMR = 2.12). Although no dose-response relationship was observed for pleural tumours, analysis of SMRs, according to both duration and intensity of exposure, revealed a considerable excess risk of death from lung tumours (SMR = 4.20) in the factory departments where exposure to hexavalent chromium was greatest and in the group of subjects who had worked in the factory for more than 10yrs.","Death risk due to cancer of the respiratory apparatus in chromate production workers Abs: This is a report on the results of a retrospective cohort study aimed at assessing the risk of death due to respiratory cancer in the workers of a chromate production plant. A total of 981 subjects had been employed for varying periods between 1948 and 1985. The study covered workers with more than 1yr of cumulative exposure, for whom the risk period starts 10yrs after beginning of exposure (latency period). Among the eligible subjects, 20 cases of respiratory tract cancer were observed: 14 located in the lung, 3 in the pleura, and 3 in the larynx. The observed deaths were compared with expected deaths on the basis of the mortality rates for Italy. The SMR was statistically significant for tumours of the pleura (SMR = 30) and the lung (SMR = 2.12). Although no dose-response relationship was observed for pleural tumours, analysis of SMRs, according to both duration and intensity of exposure, revealed a considerable excess risk of death from lung tumours (SMR = 4.20) in the factory departments where exposure to hexavalent chromium was greatest and in the group of subjects who had worked in the factory for more than 10yrs."
1576743,Cosier and  Dita 1996,Microbial reduction of hexavalent chromium in activated sludge,"BIOSIS COPYRIGHT: BIOL ABS. Three methods for reduction of the very toxic Cr(VI) to the less toxic Cr(III) were compared. It has been found that the chemical method using ferrous sulphate for reduction of Cr(VI) is less efficient and more expensive than the microbial method in which microorganisms in the activated sludge are the Cr(VI)-reducers. The third, thermal method has - in comparison to the chemical and microbial methods - the disadvantage of being much more energy-consuming and, thus, much more expensive, and the advantage of producing the least amount of final residues. In conclusion, the microbial method is preferentially recommended for reduction of Cr(VI) to Cr(III) and, consequently, for its removal from industrial waste waters.","Microbial reduction of hexavalent chromium in activated sludge Abs: BIOSIS COPYRIGHT: BIOL ABS. Three methods for reduction of the very toxic Cr(VI) to the less toxic Cr(III) were compared. It has been found that the chemical method using ferrous sulphate for reduction of Cr(VI) is less efficient and more expensive than the microbial method in which microorganisms in the activated sludge are the Cr(VI)-reducers. The third, thermal method has - in comparison to the chemical and microbial methods - the disadvantage of being much more energy-consuming and, thus, much more expensive, and the advantage of producing the least amount of final residues. In conclusion, the microbial method is preferentially recommended for reduction of Cr(VI) to Cr(III) and, consequently, for its removal from industrial waste waters."
1576742,Cognet 1984,Bronchopulmonary cancers due to occupational exposure to chromium and its derivatives,"This medical thesis deals with the variety of chromium compounds and their uses, as well as with their carcinogenicity. The choice of criteria is discussed, the advantages and limitations of various methods are presented, and the mode of action of chromium is described (hexavalent chromium is converted at the cellular level to the trivalent species, which can bind to proteins). One chapter deals with the uptake and retention of chromium, clinical and functional data, the distribution of chromium in the body and the hazards encountered in various workplaces. Preventive measures must be appropriate to each individual workplace on account of the diversity of hazards but should in general aim at limiting the spread of chromium (especially hexavalent) aerosols and their inhalation.","Bronchopulmonary cancers due to occupational exposure to chromium and its derivatives Abs: This medical thesis deals with the variety of chromium compounds and their uses, as well as with their carcinogenicity. The choice of criteria is discussed, the advantages and limitations of various methods are presented, and the mode of action of chromium is described (hexavalent chromium is converted at the cellular level to the trivalent species, which can bind to proteins). One chapter deals with the uptake and retention of chromium, clinical and functional data, the distribution of chromium in the body and the hazards encountered in various workplaces. Preventive measures must be appropriate to each individual workplace on account of the diversity of hazards but should in general aim at limiting the spread of chromium (especially hexavalent) aerosols and their inhalation."
1576741,Chen et al. 1992,Effect of pH and temperature on Cr(VI) removal from soil solution,"BIOSIS COPYRIGHT: BIOL ABS. The process of Cr(VI) removal from soil solution could be divided into two steps. The first step is a fast reaction depending mainly on the rate of Cr(VI) absorption. The second step is a slow reaction depending mainly on the rate of Cr(VI) reduction. As the pH of soil solution increased, the rate constats, K1 and K2 of Cr(VI) removal by soils decreased obviously, The influence of temperature on the kinetices of Cr(VI) removal varied with various soils and was found to be quite complicated. The influence of temperature on the removal of Cr(VI) are mainly associated with Cr(VI) adsorption and reduction.","Effect of pH and temperature on Cr(VI) removal from soil solution Abs: BIOSIS COPYRIGHT: BIOL ABS. The process of Cr(VI) removal from soil solution could be divided into two steps. The first step is a fast reaction depending mainly on the rate of Cr(VI) absorption. The second step is a slow reaction depending mainly on the rate of Cr(VI) reduction. As the pH of soil solution increased, the rate constats, K1 and K2 of Cr(VI) removal by soils decreased obviously, The influence of temperature on the kinetices of Cr(VI) removal varied with various soils and was found to be quite complicated. The influence of temperature on the removal of Cr(VI) are mainly associated with Cr(VI) adsorption and reduction."
1576739,Cavalleri and  Minoia 1985,MONITORING EXPOSURE TO CHROMIUM-VI AND CHROMIUM-III IN WORKERS BY DETERMINATION OF CHROMIUM IN URINE SERUM AND RED BLOOD CELLS,BIOSIS COPYRIGHT: BIOL ABS. RRM CHROMIUM SULFATE OCCUPATIONAL HEALTH,MONITORING EXPOSURE TO CHROMIUM-VI AND CHROMIUM-III IN WORKERS BY DETERMINATION OF CHROMIUM IN URINE SERUM AND RED BLOOD CELLS Abs: BIOSIS COPYRIGHT: BIOL ABS. RRM CHROMIUM SULFATE OCCUPATIONAL HEALTH
1576737,Budanova and  Makarova 1998,Some aspects of occupational bronchial asthma,"BIOSIS COPYRIGHT: BIOL ABS. Examination of 400 patients with occupational bronchial asthma helped to identify various clinical and pathogenetic variants of the disease in accordance with independent and combined occupational allergens and irritants. The authors evaluated diagnostic value of endonasal tests with occupational allergen, rhinocytologic tests and some specific allergologic blood tests in vitro.","Some aspects of occupational bronchial asthma Abs: BIOSIS COPYRIGHT: BIOL ABS. Examination of 400 patients with occupational bronchial asthma helped to identify various clinical and pathogenetic variants of the disease in accordance with independent and combined occupational allergens and irritants. The authors evaluated diagnostic value of endonasal tests with occupational allergen, rhinocytologic tests and some specific allergologic blood tests in vitro."
1576736,Buchancova et al. 1994,Exposure to chromium in relation to selected immunological and cytogenetic parameters in metallurgists in the production of ferrochromium alloys,"BIOSIS COPYRIGHT: BIOL ABS. The effects of exposure to chromium were studied in 40 foundry metallurgists of the mean age 39,4 | 1,5 years after the exposure lasting 14,8 | 1,5 years in the production of ferrochromium alloys ( x | SEM). The analysis of Cr was made by atomic absorption spectrophotometry (AAS). The mean all-shift concentrations of total Cr in the air of the smelting plant were 0,03-0,19 mgwere 0.02-0,03 mg of benzo(a)pyrene were 0,4-9 muge smoking habit were standardized in the control groups of a) administration employees from the neighbourhood of the plant (n=35), b) blood donors from the Ostrava town region (n=19). The authors observed, in the group of metallurgists 0,56 | 0,09 mumol Crthan in the control groups). The levels of Cr in blood, in erythrocytes and in serum in the metallurgists were higher than in the control groups. The level of Cr in Ery in the metallurgists was 0,10 | 0,008, that in the blood donors being 0,034 | 0,007 mumolllurgists was 1,34 -49,29 mumol/100 g of","Exposure to chromium in relation to selected immunological and cytogenetic parameters in metallurgists in the production of ferrochromium alloys Abs: BIOSIS COPYRIGHT: BIOL ABS. The effects of exposure to chromium were studied in 40 foundry metallurgists of the mean age 39,4 | 1,5 years after the exposure lasting 14,8 | 1,5 years in the production of ferrochromium alloys ( x | SEM). The analysis of Cr was made by atomic absorption spectrophotometry (AAS). The mean all-shift concentrations of total Cr in the air of the smelting plant were 0,03-0,19 mgwere 0.02-0,03 mg of benzo(a)pyrene were 0,4-9 muge smoking habit were standardized in the control groups of a) administration employees from the neighbourhood of the plant (n=35), b) blood donors from the Ostrava town region (n=19). The authors observed, in the group of metallurgists 0,56 | 0,09 mumol Crthan in the control groups). The levels of Cr in blood, in erythrocytes and in serum in the metallurgists were higher than in the control groups. The level of Cr in Ery in the metallurgists was 0,10 | 0,008, that in the blood donors being 0,034 | 0,007 mumolllurgists was 1,34 -49,29 mumol/100 g of"
1576735,Bragt 1981,Evaluation of the feasibility of biological monitoring of hexavalent chromium in the urine of occupationally exposed persons,"Considerations on biological monitoring as a tool in the health protection of workers exposed to water-soluble chromium(VI) compounds. Biological limits corresponding with TLV limits of chromium have been proposed in the literature. It is questionable whether these limits can be applied in the case of exposure to water-soluble chromium(VI) compounds, in view of the possibility that their toxicokinetic properties differ from those of the soluble compounds. Current laboratory investigations should reveal whether biological monitoring of urinary chromium after exposure to water-insoluble chromates is feasible.","Evaluation of the feasibility of biological monitoring of hexavalent chromium in the urine of occupationally exposed persons Abs: Considerations on biological monitoring as a tool in the health protection of workers exposed to water-soluble chromium(VI) compounds. Biological limits corresponding with TLV limits of chromium have been proposed in the literature. It is questionable whether these limits can be applied in the case of exposure to water-soluble chromium(VI) compounds, in view of the possibility that their toxicokinetic properties differ from those of the soluble compounds. Current laboratory investigations should reveal whether biological monitoring of urinary chromium after exposure to water-insoluble chromates is feasible."
1576734,Boge et al. 1983,IN-VIVO STUDY OF THE ABSORPTION OF HEXAVALENT CHROMIUM BY THE INTESTINE OF THE RAINBOW TROUT SALMO-GAIRDNERI,BIOSIS COPYRIGHT: BIOL ABS. RRM HIND GUT MUCOSA ENVIRONMENTAL POLLUTANT,IN-VIVO STUDY OF THE ABSORPTION OF HEXAVALENT CHROMIUM BY THE INTESTINE OF THE RAINBOW TROUT SALMO-GAIRDNERI Abs: BIOSIS COPYRIGHT: BIOL ABS. RRM HIND GUT MUCOSA ENVIRONMENTAL POLLUTANT
1576733,Boge et al. 1988,EFFECTS OF HEXAVALENT CHROMIUM ON ENZYMATIC ACTIVITIES AND TRANSPORT PROCESS OF INTESTINAL BRUSH BORDER MEMBRANE OF RAINBOW TROUT SALMO-GAIRDNERI,BIOSIS COPYRIGHT: BIOL ABS. RRM WATER POLLUTION AQUACULTURE ALKALINE PHOSPHATASE MALTASE TOXICOKINETICS TOXICODYNAMICS GLYCINE,EFFECTS OF HEXAVALENT CHROMIUM ON ENZYMATIC ACTIVITIES AND TRANSPORT PROCESS OF INTESTINAL BRUSH BORDER MEMBRANE OF RAINBOW TROUT SALMO-GAIRDNERI Abs: BIOSIS COPYRIGHT: BIOL ABS. RRM WATER POLLUTION AQUACULTURE ALKALINE PHOSPHATASE MALTASE TOXICOKINETICS TOXICODYNAMICS GLYCINE
1576732,Blanco JIMENEZ et al. 1991,GENERAL INFORMATION ON METAL CONTAMINATION OF FOOD ENVIRONMENTAL CAUSES DUE TO PROCESSING AND PACKAGING,BIOSIS COPYRIGHT: BIOL ABS. RRM TRACE METAL ANALYSIS ATOMIC SPECTROMETRY POLAROGRAPHY,GENERAL INFORMATION ON METAL CONTAMINATION OF FOOD ENVIRONMENTAL CAUSES DUE TO PROCESSING AND PACKAGING Abs: BIOSIS COPYRIGHT: BIOL ABS. RRM TRACE METAL ANALYSIS ATOMIC SPECTROMETRY POLAROGRAPHY
1576731,Badura et al. 1986,THE INFLUENCE OF CHROMIUM ON THE SOIL MICROFUNGI,BIOSIS COPYRIGHT: BIOL ABS. RRM CHLORIDE VS. SULFATE SALT CHROMIUM VI VS. CHROMIUM VIII,THE INFLUENCE OF CHROMIUM ON THE SOIL MICROFUNGI Abs: BIOSIS COPYRIGHT: BIOL ABS. RRM CHLORIDE VS. SULFATE SALT CHROMIUM VI VS. CHROMIUM VIII
1576730,Bacou et al. 1997,Thermal transformation of high chromium content flocculated tannery wastes with various additions of silica: Application to the colouring of container glass,"BIOSIS COPYRIGHT: BIOL ABS. A colourant is synthesized using floculated tannery wastes with high chromium content, to which silica is added previous to calcination. Mineralogical evolution is described as a function of silica content, of given granulometry, and an optimization of mineralogical composition and operating conditions is performed in order to obtain an inert product (no hexavalent chromium) and to fullfilm requirements of end-users (glass industry) in terms of colour and fusibility.","Thermal transformation of high chromium content flocculated tannery wastes with various additions of silica: Application to the colouring of container glass Abs: BIOSIS COPYRIGHT: BIOL ABS. A colourant is synthesized using floculated tannery wastes with high chromium content, to which silica is added previous to calcination. Mineralogical evolution is described as a function of silica content, of given granulometry, and an optimization of mineralogical composition and operating conditions is performed in order to obtain an inert product (no hexavalent chromium) and to fullfilm requirements of end-users (glass industry) in terms of colour and fusibility."
1576729,Arutyunyan et al. 1994,A PARTIAL ESTIMATION OF ANTHROPOGENIC RISK IN GOMEL REGION,BIOSIS COPYRIGHT: BIOL ABS. RRM RESEARCH ARTICLE HUMAN FORMALDEHYDE HEXAVALENT CHROMIUM CARCINOGEN CARBON DIOXIDE HYDROGEN SULFIDE NITROGEN DIOXIDE SULFUR DIOXIDE ENVIRONMENTAL TOXIN EXPOSURE RELATIVE RISK BELARUS,A PARTIAL ESTIMATION OF ANTHROPOGENIC RISK IN GOMEL REGION Abs: BIOSIS COPYRIGHT: BIOL ABS. RRM RESEARCH ARTICLE HUMAN FORMALDEHYDE HEXAVALENT CHROMIUM CARCINOGEN CARBON DIOXIDE HYDROGEN SULFIDE NITROGEN DIOXIDE SULFUR DIOXIDE ENVIRONMENTAL TOXIN EXPOSURE RELATIVE RISK BELARUS
1576728,Anton'Ev and  Lok 1985,OCCUPATIONAL DERMATOSES IN WORKERS ENGAGED IN THE MANUFACTURE OF ASBESTOS CEMENT PRODUCTS,BIOSIS COPYRIGHT: BIOL ABS. RRM HUMAN CHROMIUM-VI ECZEMA,OCCUPATIONAL DERMATOSES IN WORKERS ENGAGED IN THE MANUFACTURE OF ASBESTOS CEMENT PRODUCTS Abs: BIOSIS COPYRIGHT: BIOL ABS. RRM HUMAN CHROMIUM-VI ECZEMA
1576727,Amaral and  Luca S 1985,CHROMIUM-VI REMOVAL BY ADSORPTION ON POROUS COKE,BIOSIS COPYRIGHT: BIOL ABS. RRM HEAVY METAL INDUSTRIAL WASTE,CHROMIUM-VI REMOVAL BY ADSORPTION ON POROUS COKE Abs: BIOSIS COPYRIGHT: BIOL ABS. RRM HEAVY METAL INDUSTRIAL WASTE
1576726,Aksu et al. 1995,"A comparative investigation of the adsorption of copper (II), chromium (VI) and lead (II) ions to different kinds of microorganisms","BIOSIS COPYRIGHT: BIOL ABS. In this study, the adsorption of lead (II), chromium (VI) and copper (II) ions by C. vulgaris, a green algae; Z. ramigera, a bacterium; and S. cerevisiae, a yeast, which all show good adsorption abilities for heavy metal ions, was examined. Optimum initial pH, temperature and initial metal ion concentrations for adsorption were determined for all the microorganisms and metal ions. Freundlich adsorption constants were found from the Freundlich adsorption isotherms which were constituted at 25?C. Green algae was determined to be the best adsorbent among the microorganisms tested.","A comparative investigation of the adsorption of copper (II), chromium (VI) and lead (II) ions to different kinds of microorganisms Abs: BIOSIS COPYRIGHT: BIOL ABS. In this study, the adsorption of lead (II), chromium (VI) and copper (II) ions by C. vulgaris, a green algae; Z. ramigera, a bacterium; and S. cerevisiae, a yeast, which all show good adsorption abilities for heavy metal ions, was examined. Optimum initial pH, temperature and initial metal ion concentrations for adsorption were determined for all the microorganisms and metal ions. Freundlich adsorption constants were found from the Freundlich adsorption isotherms which were constituted at 25?C. Green algae was determined to be the best adsorbent among the microorganisms tested."
1576725,Aksu and  Kutsal 1994,"The investigation of adsorption of lead (II), chromium (VI) and copper (II) ions from waste waters by C. vulgaris in stirred and fluidized bed reactors","BIOSIS COPYRIGHT: BIOL ABS. In this study, the adsorption of lead (II), chromium (VI) and copper (II) ions by C. vulgaris, which is a well-known alga for the adsorption of heavy metal ions, was investigated in a batch stirred and fluidized bed reactor at constant temperature. Freundlich adsorption isotherms were developed at 25?C for each metal ion for both reactor types at optimum initial pH values found from the stirred-reactor studies. Experimental results show that adsorption and yields obtained from the fluidized bed reactor were higher than those of the stirred-tank reactor.","The investigation of adsorption of lead (II), chromium (VI) and copper (II) ions from waste waters by C. vulgaris in stirred and fluidized bed reactors Abs: BIOSIS COPYRIGHT: BIOL ABS. In this study, the adsorption of lead (II), chromium (VI) and copper (II) ions by C. vulgaris, which is a well-known alga for the adsorption of heavy metal ions, was investigated in a batch stirred and fluidized bed reactor at constant temperature. Freundlich adsorption isotherms were developed at 25?C for each metal ion for both reactor types at optimum initial pH values found from the stirred-reactor studies. Experimental results show that adsorption and yields obtained from the fluidized bed reactor were higher than those of the stirred-tank reactor."
1576717,Huet et al. 1998,"Fecal excretion and digestive transit in the chinchilla: physiological values, effect of dietary fiber intake and changes in diet",,"Fecal excretion and digestive transit in the chinchilla: physiological values, effect of dietary fiber intake and changes in diet Abs: "
1576716,de Ramirez et al. 1998,"Prevalence of bovine coccidiosis in Los Llanos de Monay, Trujillo state, Venezuela",,"Prevalence of bovine coccidiosis in Los Llanos de Monay, Trujillo state, Venezuela Abs: "
1576715,Son et al. 1998,The synthesis of betulinic acid from betulin and its solubilization with liposomes,,The synthesis of betulinic acid from betulin and its solubilization with liposomes Abs: 
1576713,Vidal et al. 2004,Determination of the digestibility of tambaqui (Colossoma macropomum) food nutrients by the techniques with internal and external indicators,,Determination of the digestibility of tambaqui (Colossoma macropomum) food nutrients by the techniques with internal and external indicators Abs: 
1576712,Kendler and  Haas 2007,A systemic drug exanthema after sclerotherapy with the chromated glycerol Scleremo,,A systemic drug exanthema after sclerotherapy with the chromated glycerol Scleremo Abs: 
1576711,Su et al. 2008,Patch Test Results in Patients with Allergic Contact Dermatitis/Mucositis,,Patch Test Results in Patients with Allergic Contact Dermatitis/Mucositis Abs: 
1576710,Karaer et al. 2009,Vaccine Production Based on Oocyst Irradiation at Broiler Coccidiosis I-Studies on the Quantitative Determination and Sporulation of Oocysts in Faeces Present in Litter of Broilers with Coccidiosis,,Vaccine Production Based on Oocyst Irradiation at Broiler Coccidiosis I-Studies on the Quantitative Determination and Sporulation of Oocysts in Faeces Present in Litter of Broilers with Coccidiosis Abs: 
1576708,Ada et al. 2010,Patch Test Results of 775 Patients with Allergic Contact Dermatitis,,Patch Test Results of 775 Patients with Allergic Contact Dermatitis Abs: 
1576707,Lucia Rengifo-Gallego et al. 2012,The effect of chromium removal by Algae-bacteria Bostrychia calliptera (Rhodomelaceae) consortia under laboratory conditions,,The effect of chromium removal by Algae-bacteria Bostrychia calliptera (Rhodomelaceae) consortia under laboratory conditions Abs: 
1576706,France and  Mathieu 1970,ISOMERISATION OF PROPYLENE OXIDE INTO PROPIONALDEHYDE ON A MIXED CHROMIUM(III) AND TUNGSTEN(VI) OXIDE .1. RELATION BETWEEN ACIDITY OF CATALYST AND ITS CATALYTIC ACTIVITY,,ISOMERISATION OF PROPYLENE OXIDE INTO PROPIONALDEHYDE ON A MIXED CHROMIUM(III) AND TUNGSTEN(VI) OXIDE .1. RELATION BETWEEN ACIDITY OF CATALYST AND ITS CATALYTIC ACTIVITY Abs: 
1576705,Bonnin 1970,CHROMIUM AMMONIUM CHROMATE NH4CR(CRO4)2,,CHROMIUM AMMONIUM CHROMATE NH4CR(CRO4)2 Abs: 
1576704,Denielou et al. 1971,"CALORIMETRIC STUDY OF SODIUM CHROMATE, MOLYBDATE AND TUNGSTATE BETWEEN 400 AND 1550 DEGREES K",,"CALORIMETRIC STUDY OF SODIUM CHROMATE, MOLYBDATE AND TUNGSTATE BETWEEN 400 AND 1550 DEGREES K Abs: "
1576703,Salapala 1971,STEREOCHEMISTRY IN INORGANIC CHEMISTRY - ACTION OF HEXAMETHYLENETETRAMINE ON CHROMIUM(VI) TRIOXIDE,,STEREOCHEMISTRY IN INORGANIC CHEMISTRY - ACTION OF HEXAMETHYLENETETRAMINE ON CHROMIUM(VI) TRIOXIDE Abs: 
1576702,SCHWARZS.M 1972,EXPERIMENTAL SENSITIZATION OF GUINEA-PIGS WITH TRIVALENT AND HEXAVALENT CHROMIUM - IN-VIVO AND IN-VITRO REACTIONS,,EXPERIMENTAL SENSITIZATION OF GUINEA-PIGS WITH TRIVALENT AND HEXAVALENT CHROMIUM - IN-VIVO AND IN-VITRO REACTIONS Abs: 
1576701,Chaisemartin 1975,"EFFECTS OF HEXAVALENT CHROMIUM COMPOUNDS ON ECKYONURUS (EPHEMEROPTERA) AND SYMPETRUM (ODONATA) ON SURVIVAL, METABOLIC-RATE AND IONOREGULATION",,"EFFECTS OF HEXAVALENT CHROMIUM COMPOUNDS ON ECKYONURUS (EPHEMEROPTERA) AND SYMPETRUM (ODONATA) ON SURVIVAL, METABOLIC-RATE AND IONOREGULATION Abs: "
1576700,Dore et al. 1976,SYNTHESIS AND STUDY OF CHARACTERISTICS OF A RESIN SPECIFIC FOR HEXAVALENT CHROMIUM,,SYNTHESIS AND STUDY OF CHARACTERISTICS OF A RESIN SPECIFIC FOR HEXAVALENT CHROMIUM Abs: 
1576699,Chaisemartin 1979,"EFFECTS OF HEXAVALENT CHROMIUM ON PREDATORS AVOIDANCE, IONIC BALANCE AND ORGANIC RESERVES OF YOUNG ATLANTO-ASTACUS PALLIPES PALLIPES (LE)",,"EFFECTS OF HEXAVALENT CHROMIUM ON PREDATORS AVOIDANCE, IONIC BALANCE AND ORGANIC RESERVES OF YOUNG ATLANTO-ASTACUS PALLIPES PALLIPES (LE) Abs: "
1576698,Chaisemartin 1979,ALIMENTARY BEHAVIOR OF YOUNG ATLANTO-ASTACUS PALLIPES PALLIPES (LE) IN THE PRESENCE OF CHROMIUM (CR+VI),,ALIMENTARY BEHAVIOR OF YOUNG ATLANTO-ASTACUS PALLIPES PALLIPES (LE) IN THE PRESENCE OF CHROMIUM (CR+VI) Abs: 
1576697,Kirkiacharian 1980,REARRANGEMENTS DURING HYDROBORATION FOLLOWED BY CHROMIC-ACID OXIDATION - NEW UNEXPECTED SYNTHESES OF 4-CHROMANONES,,REARRANGEMENTS DURING HYDROBORATION FOLLOWED BY CHROMIC-ACID OXIDATION - NEW UNEXPECTED SYNTHESES OF 4-CHROMANONES Abs: 
1576696,Szubstarski and  Gorski 1981,THE EFFECT OF POTASSIUM DICHROMATE ON GUINEA-PIG,,THE EFFECT OF POTASSIUM DICHROMATE ON GUINEA-PIG Abs: 
1576695,Bock 1985,NASAL-SEPTUM PERFORATION AFTER EXPOSURE TO CHROMIUM-VI OVER 10 YEARS,,NASAL-SEPTUM PERFORATION AFTER EXPOSURE TO CHROMIUM-VI OVER 10 YEARS Abs: 
1576694,Robert et al. 1985,PHOTOCHEMICAL BEHAVIOR OF CHROMIUM-(VI) AND (III)-ACRYLAMIDE SYSTEMS IN AQUEOUS-SOLUTION,,PHOTOCHEMICAL BEHAVIOR OF CHROMIUM-(VI) AND (III)-ACRYLAMIDE SYSTEMS IN AQUEOUS-SOLUTION Abs: 
1576693,Laborda et al. 1987,EFFECTS OF CHROMIUM(VI) IN DRINKING-WATER ON LIVER AND KIDNEY OF ALBINO-RATS,,EFFECTS OF CHROMIUM(VI) IN DRINKING-WATER ON LIVER AND KIDNEY OF ALBINO-RATS Abs: 
1576692,Boge et al. 1988,EFFECTS OF NON LETHAL CONCENTRATIONS OF HEXAVALENT CHROMIUM ON INTESTINAL ENZYMOLOGY OF SALMO-GAIRDNERI AND DICENTRARCHUS-LABRAX (PISCES),,EFFECTS OF NON LETHAL CONCENTRATIONS OF HEXAVALENT CHROMIUM ON INTESTINAL ENZYMOLOGY OF SALMO-GAIRDNERI AND DICENTRARCHUS-LABRAX (PISCES) Abs: 
1576691,Zhuravlev 1991,POTASSIUM DICHROMATE - A MODIFIER OF CHEMICAL BLASTOMOGENESIS OF THE RAT NASAL CAVITY AND PARANASAL SINUSES,It has been established that there exists cocarcinogenic influence of potassium dichromate (KD) on the chemical blastomogenesis induced by 7.12-dimethylbenz (a) anthracene (DMBA) in nasal cavity and paranasal sinuses of rats. The experiments have been carried out in 193 while noninbred male and female rats whom paraffin embols were introduced into nasal cavity with I mg of DMBA (40 animals) either with 2-5 mg of KD (48 rats) ot with I mg of DMBA and 2-5 mg of KD (60 animals). 35 rats were observed as an intact control. 10 rats got only paraffin endonasally. The cocarcinogenic effect of KD manifested in the decrease (p < 0.05) of average latent period by 76.3-77.7 days in nasal cavity and paranasal sinuses tumours in rats with I mg of DMBA and 2-5 mg of KD exposition as compared with animals whom only I mg of DMBA was administered. The endonasal administration of KD resulted in tumours induction in 4 (12.1%) rats for 315-528 days of the experiment. The cocarcinogenic influence of KD on the chemical blastomogenesis in the animals' nasal cavity and paranasal sinuses has been demonstrated for the first time.,POTASSIUM DICHROMATE - A MODIFIER OF CHEMICAL BLASTOMOGENESIS OF THE RAT NASAL CAVITY AND PARANASAL SINUSES Abs: It has been established that there exists cocarcinogenic influence of potassium dichromate (KD) on the chemical blastomogenesis induced by 7.12-dimethylbenz (a) anthracene (DMBA) in nasal cavity and paranasal sinuses of rats. The experiments have been carried out in 193 while noninbred male and female rats whom paraffin embols were introduced into nasal cavity with I mg of DMBA (40 animals) either with 2-5 mg of KD (48 rats) ot with I mg of DMBA and 2-5 mg of KD (60 animals). 35 rats were observed as an intact control. 10 rats got only paraffin endonasally. The cocarcinogenic effect of KD manifested in the decrease (p < 0.05) of average latent period by 76.3-77.7 days in nasal cavity and paranasal sinuses tumours in rats with I mg of DMBA and 2-5 mg of KD exposition as compared with animals whom only I mg of DMBA was administered. The endonasal administration of KD resulted in tumours induction in 4 (12.1%) rats for 315-528 days of the experiment. The cocarcinogenic influence of KD on the chemical blastomogenesis in the animals' nasal cavity and paranasal sinuses has been demonstrated for the first time.
1576690,Dahlke 1991,FOLLOW-UP OBSERVATIONS IN WORKERS WITH PERFORATION OF THE NASAL-SEPTUM IN AN ELECTROPLATING PLANT,,FOLLOW-UP OBSERVATIONS IN WORKERS WITH PERFORATION OF THE NASAL-SEPTUM IN AN ELECTROPLATING PLANT Abs: 
1576689,Raithel and  Zschiesche 1991,ASPECTS OF WELDING PERTINENT TO THE FIELD OF INDUSTRIAL MEDICINE WITH EMPHASIS ON POWDER FLAME SPRAYING,,ASPECTS OF WELDING PERTINENT TO THE FIELD OF INDUSTRIAL MEDICINE WITH EMPHASIS ON POWDER FLAME SPRAYING Abs: 
1576688,Triebig 1992,LUNG-CANCER IN A GALVANIZER - AN OCCUPATIONAL-DISEASE,,LUNG-CANCER IN A GALVANIZER - AN OCCUPATIONAL-DISEASE Abs: 
1576687,Hanus et al. 1992,"TESTS OF MILKOFIX, A NEW PRESERVATIVE SUBSTANCE FOR MILK SAMPLES USED FOR THE PURPOSES OF AN INFRARED-ANALYSIS OF BASIC MILK-COMPOSITION .1. CHECKS OF BACTERIOSTATIC AND BACTERICIDAL ABILITIES AND INTERFERENTIAL EFFECT",,"TESTS OF MILKOFIX, A NEW PRESERVATIVE SUBSTANCE FOR MILK SAMPLES USED FOR THE PURPOSES OF AN INFRARED-ANALYSIS OF BASIC MILK-COMPOSITION .1. CHECKS OF BACTERIOSTATIC AND BACTERICIDAL ABILITIES AND INTERFERENTIAL EFFECT Abs: "
1576686,Peters and  Schneider 1992,COMPARISON BETWEEN HYGIA-PROGESTERONE RAPID TEST AND 3H RIA,,COMPARISON BETWEEN HYGIA-PROGESTERONE RAPID TEST AND 3H RIA Abs: 
1576685,Nozaki et al. 1993,TANNERY WASTES CLEANING WITH NATURAL POLYELECTROLYTES - CHEMICAL SPECIATION STUDIES OF CHROMIUM,,TANNERY WASTES CLEANING WITH NATURAL POLYELECTROLYTES - CHEMICAL SPECIATION STUDIES OF CHROMIUM Abs: 
1576683,Grunder et al. 1994,OCCUPATIONAL ECZEMA AT THE DEPARTMENT OF DERMATOLOGY AND ANDROLOGY AT THE UNIVERSITY-OF-GIESSEN 1980-1989 - 10-YEAR FOLLOW-UP-STUDY,,OCCUPATIONAL ECZEMA AT THE DEPARTMENT OF DERMATOLOGY AND ANDROLOGY AT THE UNIVERSITY-OF-GIESSEN 1980-1989 - 10-YEAR FOLLOW-UP-STUDY Abs: 
1576682,Hegyi et al. 1994,INCIDENCE OF CONTACT ALLERGY IN WEST SLOVAKIA,,INCIDENCE OF CONTACT ALLERGY IN WEST SLOVAKIA Abs: 
1576681,Hippke and  Barth 1994,THE PROBLEMS OF CHROMIC-ACID BURNS,,THE PROBLEMS OF CHROMIC-ACID BURNS Abs: 
1576680,Geier et al. 1995,PSORIASIS PUSTULOSA PLANTARIS PROVOCATED BY LEATHER SHOES IN A PATIENT WITH ALLERGY TO CHROMATE,,PSORIASIS PUSTULOSA PLANTARIS PROVOCATED BY LEATHER SHOES IN A PATIENT WITH ALLERGY TO CHROMATE Abs: 
1576679,Kawanishi and  Hiraku 1995,Mechanism of metal-mediated oxidative DNA damage,,Mechanism of metal-mediated oxidative DNA damage Abs: 
1576678,Artyukhova et al. 1997,Changes in culture growth dynamics and cell size in a Scenedesmus quadricauda upon action of potassium dichromate,,Changes in culture growth dynamics and cell size in a Scenedesmus quadricauda upon action of potassium dichromate Abs: 
1576677,Artyukhova et al. 1997,After-effects of potassium dichromate on a culture of Scenedesmus quadricauda at a changing toxic load,,After-effects of potassium dichromate on a culture of Scenedesmus quadricauda at a changing toxic load Abs: 
1576640,Corporation 1991,Preliminary results of health risk assessments,,Preliminary results of health risk assessments Abs: 
1576639,Corporation 1992,Submission consists of two diverse summaries of prior incidents,,Submission consists of two diverse summaries of prior incidents Abs: 
1576638,Baker 1994,"Lead- and Chromate-Free Anticorrosive Primers, High Solids, 100 Percent Solids, and Waterborne Coatings as Environmentally Sound Coatings for Reclamation Infrastructures","Final rept. illustrations reproduced in black and white. reau of Reclamation investigated VOCs (volatile organic compounds) and toxic materials in protective coatings, beginning with a study of the replacement of red lead primer by lead- and chromate-free anticorrosive primers. The investigations were conducted using testing procedures appropriate to the exposures the coatings being tested would experience under field conditions. Acceptable alternative coatings systems to those currently specified, but which faced difficulties because of tightening regulations, emerged from the investigations. Many acceptable alternative coating systems require as much or more care in surface preparation and the use of more sophisticated application techniques and equipment than the systems they will replace.","Lead- and Chromate-Free Anticorrosive Primers, High Solids, 100 Percent Solids, and Waterborne Coatings as Environmentally Sound Coatings for Reclamation Infrastructures Abs: Final rept. illustrations reproduced in black and white. reau of Reclamation investigated VOCs (volatile organic compounds) and toxic materials in protective coatings, beginning with a study of the replacement of red lead primer by lead- and chromate-free anticorrosive primers. The investigations were conducted using testing procedures appropriate to the exposures the coatings being tested would experience under field conditions. Acceptable alternative coatings systems to those currently specified, but which faced difficulties because of tightening regulations, emerged from the investigations. Many acceptable alternative coating systems require as much or more care in surface preparation and the use of more sophisticated application techniques and equipment than the systems they will replace."
1576636,Zouboulis and  Goetz 1991,ION FLOTATION AS A TOOL FOR SPECIATION STUDIES SELECTIVE SEPARATION IN THE SYSTEM CR3+/CR6+,,ION FLOTATION AS A TOOL FOR SPECIATION STUDIES SELECTIVE SEPARATION IN THE SYSTEM CR3+/CR6+ Abs: 
1576635,Winder and  Carmody 2002,The dermal toxicity of cement,,The dermal toxicity of cement Abs: 
1576634,Williams and  Paustenbach 2002,Risk characterization: Principles and practice,,Risk characterization: Principles and practice Abs: 
1576633,Wiatrowski and  Barkay 2005,Monitoring of microbial metal transformations in the environment,,Monitoring of microbial metal transformations in the environment Abs: 
1576632,Wolf et al. 1988,THE INFLUENCE OF CR(III) AND CR(VI) ON DNA MELTING TEMPERATURE AND BINDING OF RADIOACTIVE CR(III) AND CR(VI) TO NUCLEIC ACIDS,,THE INFLUENCE OF CR(III) AND CR(VI) ON DNA MELTING TEMPERATURE AND BINDING OF RADIOACTIVE CR(III) AND CR(VI) TO NUCLEIC ACIDS Abs: 
1576631,Vincze et al. 2000,Altered elemental composition of the cell wall of a pseudomonas strain having inducible tolerance mechanism to chromium(VI),,Altered elemental composition of the cell wall of a pseudomonas strain having inducible tolerance mechanism to chromium(VI) Abs: 
1576629,Stensio 1971,OXIDATIONS OF ALCOHOLS WITH DIPYRIDINE-CHROMIUM(VI) OXIDE IN ACETIC ACID,,OXIDATIONS OF ALCOHOLS WITH DIPYRIDINE-CHROMIUM(VI) OXIDE IN ACETIC ACID Abs: 
1576628,Sengupta et al. 1985,KINETICS AND MECHANISM OF OXIDATION OF D-GLUCOPYRANOSE 6-PHOSPHATE AND D-RIBOFURANOSE 5-PHOSPHATE BY CHROMIUM(VI) IN PERCHLORIC-ACID MEDIA,,KINETICS AND MECHANISM OF OXIDATION OF D-GLUCOPYRANOSE 6-PHOSPHATE AND D-RIBOFURANOSE 5-PHOSPHATE BY CHROMIUM(VI) IN PERCHLORIC-ACID MEDIA Abs: 
1576627,Turick and  Apel 1997,A bioprocessing strategy that allows for the selection of Cr(VI)-reducing bacteria from soils,"BIOSIS COPYRIGHT: BIOL ABS. Anaerobic bacteria that reduce hexavalent chromium (Cr(VI)) to trivalent (Cr(III)) are common in soils and were used to develop a bioprocess employing a selection strategy. Indigenous Cr(VI)-reducers were enriched from Cr(VI)-contaminated soil under anaerobic conditions. The mixed culture was then tested for Cr(VI)-reducing activity in a chemostat, followed by transfer to a 1-L packed-bed bioreactor operated at 30? C for additional study. The support material used in the reactor consisted of 6-mm porcelain saddles. Cr(VI) concentrations in the liquid ranged from 140-750 mg L-1. Cr(VI)-reducing bacteria were the dominant population with Cr(VI)-reduction rates of approximately 0.71 mg g-1 dry cells h-1 achieved at Cr(VI) concentrations of 750 mg L-1. These results indicate a potential for selecting and maintaining indigenous Cr(VI)-reducers in a bioreactor for Cr(VI)-remediation of groundwater or soil wash effluents.","A bioprocessing strategy that allows for the selection of Cr(VI)-reducing bacteria from soils Abs: BIOSIS COPYRIGHT: BIOL ABS. Anaerobic bacteria that reduce hexavalent chromium (Cr(VI)) to trivalent (Cr(III)) are common in soils and were used to develop a bioprocess employing a selection strategy. Indigenous Cr(VI)-reducers were enriched from Cr(VI)-contaminated soil under anaerobic conditions. The mixed culture was then tested for Cr(VI)-reducing activity in a chemostat, followed by transfer to a 1-L packed-bed bioreactor operated at 30? C for additional study. The support material used in the reactor consisted of 6-mm porcelain saddles. Cr(VI) concentrations in the liquid ranged from 140-750 mg L-1. Cr(VI)-reducing bacteria were the dominant population with Cr(VI)-reduction rates of approximately 0.71 mg g-1 dry cells h-1 achieved at Cr(VI) concentrations of 750 mg L-1. These results indicate a potential for selecting and maintaining indigenous Cr(VI)-reducers in a bioreactor for Cr(VI)-remediation of groundwater or soil wash effluents."
1576626,Sengupta et al. 1981,KINETICS AND MECHANISM OF OXIDATION OF D-FRUCTOSE AND L-SORBOSE BY CHROMIUM(VI) AND VANADIUM(V) IN PERCHLORIC-ACID MEDIUM,,KINETICS AND MECHANISM OF OXIDATION OF D-FRUCTOSE AND L-SORBOSE BY CHROMIUM(VI) AND VANADIUM(V) IN PERCHLORIC-ACID MEDIUM Abs: 
1576625,Sengupta and  Basu 1980,KINETICS AND MECHANISM OF OXIDATION OF D-GLUCOSE AND D-RIBOSE BY CHROMIUM(VI) AND VANADIUM(V) IN PERCHLORIC-ACID MEDIUM,,KINETICS AND MECHANISM OF OXIDATION OF D-GLUCOSE AND D-RIBOSE BY CHROMIUM(VI) AND VANADIUM(V) IN PERCHLORIC-ACID MEDIUM Abs: 
1576624,Sengupta and  Basu 1980,KINETICS AND MECHANISM OF OXIDATION OF D-ERYTHROSE AND DL-GLYCERALDE BY CHROMIUM(VI) AND VANADIUM(V) IN PERCHLORIC-ACID MEDIUM,,KINETICS AND MECHANISM OF OXIDATION OF D-ERYTHROSE AND DL-GLYCERALDE BY CHROMIUM(VI) AND VANADIUM(V) IN PERCHLORIC-ACID MEDIUM Abs: 
1576623,Sen and  Dastidar 2010,CHROMIUM REMOVAL USING VARIOUS BIOSORBENTS,,CHROMIUM REMOVAL USING VARIOUS BIOSORBENTS Abs: 
1576622,Rej et al. 1989,CHROMIC-ACID OXIDATION IN THE SYNTHESIS OF URONIC-ACIDS - USE OF THE ORTHO-LEVULINOYL GROUP TO MINIMIZE ACYL MIGRATION,,CHROMIC-ACID OXIDATION IN THE SYNTHESIS OF URONIC-ACIDS - USE OF THE ORTHO-LEVULINOYL GROUP TO MINIMIZE ACYL MIGRATION Abs: 
1576621,Quinlan and  Gutteridge 1987,OXYGEN RADICAL DAMAGE TO DNA BY RIFAMYCIN SV AND COPPER IONS,,OXYGEN RADICAL DAMAGE TO DNA BY RIFAMYCIN SV AND COPPER IONS Abs: 
1576620,Sawatari 1986,Sampling filters and dissolution methods for differential determination of water-soluble chromium (VI) and chromium (III) in particulate substances,,Sampling filters and dissolution methods for differential determination of water-soluble chromium (VI) and chromium (III) in particulate substances Abs: 
1576619,Sala et al. 2011,Detection and structural characterization of oxo-chromium(V)-sugar complexes by electron paramagnetic resonance,"This article describes the detection and characterization of oxo-Cr(V)-saccharide coordination compounds, produced during chromic oxidation of carbohydrates by Cr(VI) and Cr(V), using electron paramagnetic resonance (EPR) spectroscopy. After an introduction into the main importance of chromium (bio)chemistry, and more specifically the oxo-chromium(V)-sugar complexes, a general overview is given of the current state-of-the-art EPR techniques. The next step reviews which types of EPR spectroscopy are currently applied to oxo-Cr(V) complexes, and what information about these systems can be gained from such experiments. The advantages and pitfalls of the different approaches are discussed, and it is shown that the potential of high-field and pulsed EPR techniques is as yet still largely unexploited in the field of oxo-Cr(V) complexes. Subsequently, the discussion focuses on the analysis of oxo-Cr(V) complexes of different types of sugars and the implications of the results in terms of understanding chromium (bio)chemistry.","Detection and structural characterization of oxo-chromium(V)-sugar complexes by electron paramagnetic resonance Abs: This article describes the detection and characterization of oxo-Cr(V)-saccharide coordination compounds, produced during chromic oxidation of carbohydrates by Cr(VI) and Cr(V), using electron paramagnetic resonance (EPR) spectroscopy. After an introduction into the main importance of chromium (bio)chemistry, and more specifically the oxo-chromium(V)-sugar complexes, a general overview is given of the current state-of-the-art EPR techniques. The next step reviews which types of EPR spectroscopy are currently applied to oxo-Cr(V) complexes, and what information about these systems can be gained from such experiments. The advantages and pitfalls of the different approaches are discussed, and it is shown that the potential of high-field and pulsed EPR techniques is as yet still largely unexploited in the field of oxo-Cr(V) complexes. Subsequently, the discussion focuses on the analysis of oxo-Cr(V) complexes of different types of sugars and the implications of the results in terms of understanding chromium (bio)chemistry."
1576618,Petrilli and  Deflora 1978,OXIDATION OF INACTIVE TRIVALENT CHROMIUM TO MUTAGENIC HEXAVALENT FORM,,OXIDATION OF INACTIVE TRIVALENT CHROMIUM TO MUTAGENIC HEXAVALENT FORM Abs: 
1576617,Parimala et al. 2004,Phytoremediation of chromium from seawater using five different products from coconut husk,,Phytoremediation of chromium from seawater using five different products from coconut husk Abs: 
1576615,Mohanty and  Patra 2011,Attenuation of Chromium Toxicity by Bioremediation Technology,,Attenuation of Chromium Toxicity by Bioremediation Technology Abs: 
1576614,Peralta-Videa et al. 2002,"Potential of alfalfa plant to phytoremediate individually contaminated montmorillonite-soils with cadmium(II), chromium(VI), copper (II), nickel(II), and zinc(II)",,"Potential of alfalfa plant to phytoremediate individually contaminated montmorillonite-soils with cadmium(II), chromium(VI), copper (II), nickel(II), and zinc(II) Abs: "
1576613,Park et al. 2006,Mechanisms of the removal of hexavalent chromium by biomaterials or biomaterial-based activated carbons,"Three papers published during recent 2 years in Journal of Hazardous Materials made a mistake in analyzing chromium species in aqueous solution, resulting in incorrect elucidation of Cr(VI) biosorption; the Cr(VI) was removed from aqueous solution systems by 'anionic adsorption'. However, it has been proved that Cr(VI) is easily reduced to Cr(III) by contact with organic materials under acidic conditions because of its high redox potential value (above +1.3 V at standard condition). Therefore, it is strongly possible that the mechanism of Cr(VI) removal by biomaterials or biomaterial-based activated carbons is not &quot;anionic adsorption&quot; but &quot;adsorption-coupled reduction&quot;. Thus, for researches of Cr(VI) biosorption, researchers have to analyze not only Cr(VI) but also total Cr in aqueous solution and to check the oxidation state of chromium bound on the biomaterials or activated carbons.","Mechanisms of the removal of hexavalent chromium by biomaterials or biomaterial-based activated carbons Abs: Three papers published during recent 2 years in Journal of Hazardous Materials made a mistake in analyzing chromium species in aqueous solution, resulting in incorrect elucidation of Cr(VI) biosorption; the Cr(VI) was removed from aqueous solution systems by 'anionic adsorption'. However, it has been proved that Cr(VI) is easily reduced to Cr(III) by contact with organic materials under acidic conditions because of its high redox potential value (above +1.3 V at standard condition). Therefore, it is strongly possible that the mechanism of Cr(VI) removal by biomaterials or biomaterial-based activated carbons is not &quot;anionic adsorption&quot; but &quot;adsorption-coupled reduction&quot;. Thus, for researches of Cr(VI) biosorption, researchers have to analyze not only Cr(VI) but also total Cr in aqueous solution and to check the oxidation state of chromium bound on the biomaterials or activated carbons."
1576612,Minoia et al. 1983,Electrothermal atomisation atomic-absorption spectrophotometric determination of chromium(VI) in urine by solvent extraction separation with liquid anion exchangers,,Electrothermal atomisation atomic-absorption spectrophotometric determination of chromium(VI) in urine by solvent extraction separation with liquid anion exchangers Abs: 
1576611,Mason and  Coco 1955,Purification of chromium (VI) for use in the PBI determination,,Purification of chromium (VI) for use in the PBI determination Abs: 
1576610,Ladou et al. 2007,American College of Occupational and Environmental Medicine (ACOEM): A professional association in service to industry,,American College of Occupational and Environmental Medicine (ACOEM): A professional association in service to industry Abs: 
1576609,Krishnani and  Ayyappan 2006,Heavy metals remediation of water using plants and lignocellulosic agrowastes,,Heavy metals remediation of water using plants and lignocellulosic agrowastes Abs: 
1576608,Kiely et al. 1973,"OXIDATION OF CARBOHYDRATES WITH CHROMIC ACID - SYNTHESIS OF DELTA-DICARBONYL MONOSACCHARIDES 6-DEOXY-D-XYLO-HEXOS-5-ULOSE AND 6,7-DIDEOXY-D-XYLO-HEPTOS-5-ULOSE",,"OXIDATION OF CARBOHYDRATES WITH CHROMIC ACID - SYNTHESIS OF DELTA-DICARBONYL MONOSACCHARIDES 6-DEOXY-D-XYLO-HEXOS-5-ULOSE AND 6,7-DIDEOXY-D-XYLO-HEPTOS-5-ULOSE Abs: "
1576607,Kamaludeen et al. 2003,Chromium-microorganism interactions in soils: Remediation implications,,Chromium-microorganism interactions in soils: Remediation implications Abs: 
1576606,Magnus 1958,"The conjugation of nickel, cobalt, hexavalent chromium, and eosin with protein as shown by paper electrophoresis",,"The conjugation of nickel, cobalt, hexavalent chromium, and eosin with protein as shown by paper electrophoresis Abs: "
1576605,Heaton et al. 1989,STUDIES WITH NONRADIOISOTOPIC SODIUM CHROMATE .1. DEVELOPMENT OF A TECHNIQUE FOR MEASURING RED-CELL VOLUME,,STUDIES WITH NONRADIOISOTOPIC SODIUM CHROMATE .1. DEVELOPMENT OF A TECHNIQUE FOR MEASURING RED-CELL VOLUME Abs: 
1576604,Hatanaka and  Ohno 1971,LEAF ALCOHOL .19. CHROMIC ACID OXIDATION OF ISOMERIC HEXENOLS,,LEAF ALCOHOL .19. CHROMIC ACID OXIDATION OF ISOMERIC HEXENOLS Abs: 
1576603,Goswami and  Banerji 1971,KINETICS OF OXIDATION OF ALIPHATIC ALDEHYDES BY CHROMIC ACID,,KINETICS OF OXIDATION OF ALIPHATIC ALDEHYDES BY CHROMIC ACID Abs: 
1576602,Fasulo et al. 1983,CYTO-TOXIC EFFECTS OF HEXAVALENT CHROMIUM IN EUGLENA-GRACILIS .2. PHYSIOLOGICAL AND ULTRASTRUCTURAL STUDIES,,CYTO-TOXIC EFFECTS OF HEXAVALENT CHROMIUM IN EUGLENA-GRACILIS .2. PHYSIOLOGICAL AND ULTRASTRUCTURAL STUDIES Abs: 
1576601,Fasulo et al. 1982,CYTO-TOXIC EFFECTS OF HEXAVALENT CHROMIUM IN EUGLENA-GRACILIS .1. 1ST OBSERVATIONS,,CYTO-TOXIC EFFECTS OF HEXAVALENT CHROMIUM IN EUGLENA-GRACILIS .1. 1ST OBSERVATIONS Abs: 
1576600,Hamilton and  Wetterhahn 1989,DIFFERENTIAL EFFECTS OF THE GENOTOXIC CARCINOGEN CHROMIUM(VI) ON CONSTITUTIVE AND INDUCIBLE GENE EXPRESSION IN VIVO,,DIFFERENTIAL EFFECTS OF THE GENOTOXIC CARCINOGEN CHROMIUM(VI) ON CONSTITUTIVE AND INDUCIBLE GENE EXPRESSION IN VIVO Abs: 
1576599,Hamilton and  Wetterhahn 1988,DIFFERENTIAL EFFECT OF THE CARCINOGEN CHROMIUM(VI) ON GENE EXPRESSION IN VIVO,,DIFFERENTIAL EFFECT OF THE CARCINOGEN CHROMIUM(VI) ON GENE EXPRESSION IN VIVO Abs: 
1576598,Eastmond et al. 2008,Trivalent chromium: Assessing the genotoxic risk of an essential trace element and widely used human and animal nutritional supplement,,Trivalent chromium: Assessing the genotoxic risk of an essential trace element and widely used human and animal nutritional supplement Abs: 
1576597,Dorn et al. 1987,HEXAVALENT CHROMIUM AS A REFERENCE TOXICANT IN EFFLUENT TOXICITY TESTS,,HEXAVALENT CHROMIUM AS A REFERENCE TOXICANT IN EFFLUENT TOXICITY TESTS Abs: 
1576596,Corradi and  Gorbi 1993,CHROMIUM TOXICITY ON 2 LINKED TROPHIC LEVELS .2. MORPHOPHYSIOLOGICAL EFFECTS ON SCENEDESMUS-ACUTUS,,CHROMIUM TOXICITY ON 2 LINKED TROPHIC LEVELS .2. MORPHOPHYSIOLOGICAL EFFECTS ON SCENEDESMUS-ACUTUS Abs: 
1576595,Duffy 2006,CrVI: new regulations and detection methods,,CrVI: new regulations and detection methods Abs: 
1576594,Das et al. 2011,Hexavalent chromium and its effect on health: possible protective role of garlic (Allium sativum Linn),"Hexavalent chromium or chromium (VI) is a powerful epithelial irritant and a confirmed human carcinogen. This heavy metal is toxic to many plants, aquatic animals, and bacteria. Chromium (VI) which consists of 10%-15% total chromium usage, is principally used for metal plating (H2Cr2O7), as dyes, paint pigments, and leather tanning, etc. Industrial production of chromium (II) and (III) compounds are also available but in small amounts as compared to chromium (VI). Chromium (VI) can act as an oxidant directly on the skin surface or it can be absorbed through the skin, especially if the skin surface is damaged. The prooxidative effects of chromium (VI) inhibit antioxidant enzymes and deplete intracellular glutathione in living systems and act as hematotoxic, immunotoxic, hepatotoxic, pulmonary toxic, and nephrotoxic agents. In this review, we particularly address the hexavalent chromium-induced generation of reactive oxygen species and increased lipid peroxidation in humans and animals, and the possible role of garlic (Allium sativum Linn) as a protective antioxidant.","Hexavalent chromium and its effect on health: possible protective role of garlic (Allium sativum Linn) Abs: Hexavalent chromium or chromium (VI) is a powerful epithelial irritant and a confirmed human carcinogen. This heavy metal is toxic to many plants, aquatic animals, and bacteria. Chromium (VI) which consists of 10%-15% total chromium usage, is principally used for metal plating (H2Cr2O7), as dyes, paint pigments, and leather tanning, etc. Industrial production of chromium (II) and (III) compounds are also available but in small amounts as compared to chromium (VI). Chromium (VI) can act as an oxidant directly on the skin surface or it can be absorbed through the skin, especially if the skin surface is damaged. The prooxidative effects of chromium (VI) inhibit antioxidant enzymes and deplete intracellular glutathione in living systems and act as hematotoxic, immunotoxic, hepatotoxic, pulmonary toxic, and nephrotoxic agents. In this review, we particularly address the hexavalent chromium-induced generation of reactive oxygen species and increased lipid peroxidation in humans and animals, and the possible role of garlic (Allium sativum Linn) as a protective antioxidant."
1576592,Brochiero et al. 1984,TOXIC ACTION OF HEXAVALENT CHROMIUM ON EUGLENA-GRACILIS CELLS STRAIN-Z GROWN UNDER HETEROTROPHIC CONDITIONS,,TOXIC ACTION OF HEXAVALENT CHROMIUM ON EUGLENA-GRACILIS CELLS STRAIN-Z GROWN UNDER HETEROTROPHIC CONDITIONS Abs: 
1576591,Avudainayagam et al. 2003,Chemistry of chromium in soils with emphasis on tannery waste sites,,Chemistry of chromium in soils with emphasis on tannery waste sites Abs: 
1576580,Inc 1991,Human exposure,,Human exposure Abs: 
1576579,Inc 1992,Carcinogenic risk assessment for a facility in California. Human exposure (monitoring) env. occurrence/release/fate production/use,,Carcinogenic risk assessment for a facility in California. Human exposure (monitoring) env. occurrence/release/fate production/use Abs: 
1576578,Inc 1991,Preliminary data on hexavalent chromium exposure,,Preliminary data on hexavalent chromium exposure Abs: 
1576577,Corporation 1991,Human exposure,,Human exposure Abs: 
1576576,Corporation 1991,Human exposure,,Human exposure Abs: 
1576574,Vranken et al. 1989,EFFECT OF TEMPERATURE AND FOOD ON HEXAVALENT CHROMIUM TOXICITY TO THE MARINE NEMATODE MONHYSTERA-DISJUNCTA,,EFFECT OF TEMPERATURE AND FOOD ON HEXAVALENT CHROMIUM TOXICITY TO THE MARINE NEMATODE MONHYSTERA-DISJUNCTA Abs: 
1576572,Vanderputte et al. 1982,EFFECTS OF HEXAVALENT CHROMIUM IN RAINBOW-TROUT (SALMO-GAIRDNERI) AFTER PROLONGED EXPOSURE AT 2 DIFFERENT PH LEVELS,,EFFECTS OF HEXAVALENT CHROMIUM IN RAINBOW-TROUT (SALMO-GAIRDNERI) AFTER PROLONGED EXPOSURE AT 2 DIFFERENT PH LEVELS Abs: 
1576571,Vanderputte and  Part 1982,OXYGEN AND CHROMIUM TRANSFER IN PERFUSED GILLS OF RAINBOW-TROUT (SALMO-GAIRDNERI) EXPOSED TO HEXAVALENT CHROMIUM AT 2 DIFFERENT PH LEVELS,,OXYGEN AND CHROMIUM TRANSFER IN PERFUSED GILLS OF RAINBOW-TROUT (SALMO-GAIRDNERI) EXPOSED TO HEXAVALENT CHROMIUM AT 2 DIFFERENT PH LEVELS Abs: 
1576570,DuPont 1992,Ecotoxicity,,Ecotoxicity Abs: 
1576569,API 1982,Ecotoxicity,,Ecotoxicity Abs: 
1576568,API 1981,Ecotoxicity,,Ecotoxicity Abs: 
1576557,Trabalka and  Gehrs 1977,OBSERVATION ON TOXICITY OF HEXAVALENT CHROMIUM TO DAPHNIA-MAGNA,,OBSERVATION ON TOXICITY OF HEXAVALENT CHROMIUM TO DAPHNIA-MAGNA Abs: 
1576556,Sousa et al. 1998,Comparative PTA staining of molluscan spermatozoa,,Comparative PTA staining of molluscan spermatozoa Abs: 
1576555,Shanker et al. 2009,Chromium interactions in plants: current status and future strategies,,Chromium interactions in plants: current status and future strategies Abs: 
1576554,Rudel et al. 2001,Quantification of soluble chromium(VI) in soils and evaluation of ecotoxicological effects,,Quantification of soluble chromium(VI) in soils and evaluation of ecotoxicological effects Abs: 
1576553,Riedel 1985,"THE RELATIONSHIP BETWEEN CHROMIUM(VI) UPTAKE, SULFATE UPTAKE, AND CHROMIUM(VI) TOXICITY IN THE ESTUARINE DIATOM THALASSIOSIRA-PSEUDONANA",,"THE RELATIONSHIP BETWEEN CHROMIUM(VI) UPTAKE, SULFATE UPTAKE, AND CHROMIUM(VI) TOXICITY IN THE ESTUARINE DIATOM THALASSIOSIRA-PSEUDONANA Abs: "
1576552,Rayburn and  Aladdin 2003,"Developmental toxicity of copper, chromium, and aluminum using the shrimp embryo teratogenesis assay: Palaemonid with artificial seawater",,"Developmental toxicity of copper, chromium, and aluminum using the shrimp embryo teratogenesis assay: Palaemonid with artificial seawater Abs: "
1576550,Pickering 1988,EVALUATION AND COMPARISON OF TWO SHORT-TERM FATHEAD MINNOW TESTS FOR ESTIMATING CHRONIC TOXICITY,,EVALUATION AND COMPARISON OF TWO SHORT-TERM FATHEAD MINNOW TESTS FOR ESTIMATING CHRONIC TOXICITY Abs: 
1576549,Ramusino et al. 1981,Influence of chromium (VI) upon stream Ephemeroptera in the pre-Alps,,Influence of chromium (VI) upon stream Ephemeroptera in the pre-Alps Abs: 
1576548,Outridge and  Scheuhammer 1993,Bioaccumulation and toxicology of chromium: implications for wildlife,"The major source of exposure to Cr for wild birds and mammals is through ingestion with food. Chromium(VI) compounds are absorbed significantly more efficiently (2-10% of dose) from the GI tract than inorganic Cr(III) compounds (0.5-3%), due to the increased membrane permeability of the former. Transfer of Cr(VI) into mammalian fetuses has been documented at oral doses of 500 mg Cr/L in drinking water, and injected single doses of 5 mg Cr(VI)/kg BW in dams were teratogenic. Cr concentration data for mammalian and avian wildlife species and their potential food organisms are scarce. Worldwide, fewer than 50 species of free-living mammals and birds have been surveyed with regard to tissue Cr concentrations. Tissue concentrations in animals living in habitats remote from sources of Cr contamination range from approximately 0.1-15 micrograms/g DW depending on the species and tissue analyzed. In habitats experiencing Cr pollution, levels can be up to two orders of magnitude higher. Eisler (1986) suggested that tissue concentrations in wildlife &gt; 4 micrograms/g DW be considered to indicate likely contamination by Cr. Bone tissue often accumulates higher concentrations than other tissues in animals chronically exposed to Cr. Measuring concentrations only in the liver and/or kidneys has been a common practice, yet these organs failed to show evidence of extant Cr contamination in some cases. It is recommended that analysis of the bone, liver, and kidneys be a minimum requirement for future Cr biomonitoring studies. Concentrations in fur or feathers can be extremely variable even among individuals within the same habitat. At best, concentrations in fur and feathers might be used to indicate relative levels of airborne Cr contamination. The toxicological significance of &quot;elevated&quot; Cr concentrations is largely unknown because toxicological data on free-living wildlife species are virtually nonexistent. Based on controlled dosing studies in which Cr compounds were administered orally to experimental animals, dietary Cr concentrations &gt; or = 10 micrograms/g DW in food should be considered potentially harmful to the health and reproductive success of wildlife consumers. Certain species of fish and aquatic invertebrates are sensitive to Cr, showing reduced survival or growth at Cr(VI) concentrations &gt; 10 micrograms/L. The elimination of these organisms from environments contaminated with Cr may have detrimental effects on wild birds and mammals that depend on such organisms for food.(ABSTRACT TRUNCATED AT 400 WORDS)","Bioaccumulation and toxicology of chromium: implications for wildlife Abs: The major source of exposure to Cr for wild birds and mammals is through ingestion with food. Chromium(VI) compounds are absorbed significantly more efficiently (2-10% of dose) from the GI tract than inorganic Cr(III) compounds (0.5-3%), due to the increased membrane permeability of the former. Transfer of Cr(VI) into mammalian fetuses has been documented at oral doses of 500 mg Cr/L in drinking water, and injected single doses of 5 mg Cr(VI)/kg BW in dams were teratogenic. Cr concentration data for mammalian and avian wildlife species and their potential food organisms are scarce. Worldwide, fewer than 50 species of free-living mammals and birds have been surveyed with regard to tissue Cr concentrations. Tissue concentrations in animals living in habitats remote from sources of Cr contamination range from approximately 0.1-15 micrograms/g DW depending on the species and tissue analyzed. In habitats experiencing Cr pollution, levels can be up to two orders of magnitude higher. Eisler (1986) suggested that tissue concentrations in wildlife &gt; 4 micrograms/g DW be considered to indicate likely contamination by Cr. Bone tissue often accumulates higher concentrations than other tissues in animals chronically exposed to Cr. Measuring concentrations only in the liver and/or kidneys has been a common practice, yet these organs failed to show evidence of extant Cr contamination in some cases. It is recommended that analysis of the bone, liver, and kidneys be a minimum requirement for future Cr biomonitoring studies. Concentrations in fur or feathers can be extremely variable even among individuals within the same habitat. At best, concentrations in fur and feathers might be used to indicate relative levels of airborne Cr contamination. The toxicological significance of &quot;elevated&quot; Cr concentrations is largely unknown because toxicological data on free-living wildlife species are virtually nonexistent. Based on controlled dosing studies in which Cr compounds were administered orally to experimental animals, dietary Cr concentrations &gt; or = 10 micrograms/g DW in food should be considered potentially harmful to the health and reproductive success of wildlife consumers. Certain species of fish and aquatic invertebrates are sensitive to Cr, showing reduced survival or growth at Cr(VI) concentrations &gt; 10 micrograms/L. The elimination of these organisms from environments contaminated with Cr may have detrimental effects on wild birds and mammals that depend on such organisms for food.(ABSTRACT TRUNCATED AT 400 WORDS)"
1576538,Hauschild 1993,"PUTRESCINE (1,4-DIAMINOBUTANE) AS AN INDICATOR OF POLLUTION-INDUCED STRESS IN HIGHER-PLANTS - BARLEY AND RAPE STRESSED WITH CR(III) OR CR(VI)",,"PUTRESCINE (1,4-DIAMINOBUTANE) AS AN INDICATOR OF POLLUTION-INDUCED STRESS IN HIGHER-PLANTS - BARLEY AND RAPE STRESSED WITH CR(III) OR CR(VI) Abs: "
1576536,Gashi et al. 2008,Some biochemical parameters and histological findings in the kidneys of Hybro chickens treated with chromium (VI) and vitamin C,,Some biochemical parameters and histological findings in the kidneys of Hybro chickens treated with chromium (VI) and vitamin C Abs: 
1576534,Bajraktari et al. 2008,The effects of chromium (VI) and vitamin C on the frequency of micronucleated erythrocytes in Hybro chicken,,The effects of chromium (VI) and vitamin C on the frequency of micronucleated erythrocytes in Hybro chicken Abs: 
1576532,Hayat et al. 2012,Physiological changes induced by chromium stress in plants: an overview,This article presents an overview of the mechanism of chromium (Cr) stress in plants. Toxic effects of Cr on plant growth and development depend primarily on its valence state. Cr(VI) is highly toxic and mobile whereas Cr(III) is less toxic. Cr-induced oxidative stress involves induction of lipid peroxidation in plants that cause severe damage to cell membranes which includes degradation of photosynthetic pigments causing deterioration in growth. The potential of plants with the adequacy to accumulate or to stabilize Cr compounds for bioremediation of Cr contamination has gained engrossment in recent years.,Physiological changes induced by chromium stress in plants: an overview Abs: This article presents an overview of the mechanism of chromium (Cr) stress in plants. Toxic effects of Cr on plant growth and development depend primarily on its valence state. Cr(VI) is highly toxic and mobile whereas Cr(III) is less toxic. Cr-induced oxidative stress involves induction of lipid peroxidation in plants that cause severe damage to cell membranes which includes degradation of photosynthetic pigments causing deterioration in growth. The potential of plants with the adequacy to accumulate or to stabilize Cr compounds for bioremediation of Cr contamination has gained engrossment in recent years.
1576522,Mattagajasingh and  Misra 1994,PARTIAL SEQUENCING OF A PROTEIN CROSS-LINKING TO DNA UPON TREATMENT OF CULTURED INTACT HUMAN-CELLS (MOLT4) WITH THE CARCINOGEN CHROMIUM(VI),,PARTIAL SEQUENCING OF A PROTEIN CROSS-LINKING TO DNA UPON TREATMENT OF CULTURED INTACT HUMAN-CELLS (MOLT4) WITH THE CARCINOGEN CHROMIUM(VI) Abs: 
1576521,Hojo and  Okado 1996,Chromium(VI): Toxicity and reactive intermediates,,Chromium(VI): Toxicity and reactive intermediates Abs: 
1576519,Popper et al. 1990,Cytotoxicity of chromium compounds: Comparison of in vitro and in vivo tests,"Chromium (Cr) is widely used in the steel industry and also in dyes for the introduction of yellow to orange colors. In recent years chromium has been proven to be toxic and a possible carcinogen (7). The mechanism of chromium toxicity is still unknown. In inhalation studies mainly nodular accumulations of alveolar macrophages and disturbances of surfactant distribution and synthesis were found (3,4). The induction of interstitial pneumonia either as diffuse alveolar damage or desquamative interstitial pneumonia as one of the usual reactions of lung tissue to inhaled toxic foreign materials was not reported in these studies (3).","Cytotoxicity of chromium compounds: Comparison of in vitro and in vivo tests Abs: Chromium (Cr) is widely used in the steel industry and also in dyes for the introduction of yellow to orange colors. In recent years chromium has been proven to be toxic and a possible carcinogen (7). The mechanism of chromium toxicity is still unknown. In inhalation studies mainly nodular accumulations of alveolar macrophages and disturbances of surfactant distribution and synthesis were found (3,4). The induction of interstitial pneumonia either as diffuse alveolar damage or desquamative interstitial pneumonia as one of the usual reactions of lung tissue to inhaled toxic foreign materials was not reported in these studies (3)."
1576518,Loeb et al. 1984,DEPURINATED SITES ON DNA AS COMMON INTERMEDIATES IN MUTAGENESIS,,DEPURINATED SITES ON DNA AS COMMON INTERMEDIATES IN MUTAGENESIS Abs: 
1576517,Hartwig et al. 1990,"GENOTOXICITY AND INHIBITION OF DNA REPAIR BY COMPOUNDS OF CHROMIUM, NICKEL, LEAD AND CADMIUM",,"GENOTOXICITY AND INHIBITION OF DNA REPAIR BY COMPOUNDS OF CHROMIUM, NICKEL, LEAD AND CADMIUM Abs: "
1576514,Douglas et al. 1980,"EFFECT OF LEAD CHROMATE ON CHROMOSOME ABERRATION, SISTER CHROMATID EXCHANGE AND DNA DAMAGE IN MAMMALIAN CELLS IN VITRO",,"EFFECT OF LEAD CHROMATE ON CHROMOSOME ABERRATION, SISTER CHROMATID EXCHANGE AND DNA DAMAGE IN MAMMALIAN CELLS IN VITRO Abs: "
1576513,Brown 1948,"Health hazards from lead paint and zinc chromate paint; incidence in modern construction, maintenance and scrapping of ships",,"Health hazards from lead paint and zinc chromate paint; incidence in modern construction, maintenance and scrapping of ships Abs: "
1576512,Germany 1987,Acute Toxicity,,Acute Toxicity Abs: 
1576511,Inc 1978,Acute Toxicity,,Acute Toxicity Abs: 
1576510,OxyChem 1992,Acute Toxicity,ACUTE ORAL TOXICITY IN RATS IS HIGH CONCERN WITH AN LD50 OF 50 MG/KG. THE TEST AL WAS CORROSIVE TO THE GI TRACT. ACUTE DERMAL TOXICITY IN RATS IS HIGH N WITH AN LD50 OF 55 MG/KG. SEVERE SKIN IRRITATION AND KIDNEY EFFECTS OTED.,Acute Toxicity Abs: ACUTE ORAL TOXICITY IN RATS IS HIGH CONCERN WITH AN LD50 OF 50 MG/KG. THE TEST AL WAS CORROSIVE TO THE GI TRACT. ACUTE DERMAL TOXICITY IN RATS IS HIGH N WITH AN LD50 OF 55 MG/KG. SEVERE SKIN IRRITATION AND KIDNEY EFFECTS OTED.
1576509,Complany 1992,Neurotoxicity,"ACUTE ORAL TOXICITY IN RATS IS OF HIGH CONCERN. SINGLE ORAL DOSES OF 10-3200 IN 9 RATS WERE ASSOCIATED WITH SIGNS OF NEUROTOXICITY AND MORTALITY TENT WITH AN ORAL LD50 OF 25-50 MG/KG. MORTALITIES OCCURRED FROM 45 S TO 1 DAY FOLLOWING DOSING AND TREATED ANIMALS WERE NOTED TO BE WEAK, , WITH DARK EYES AND/OR WERE OBSERVED TO THROW THEMSELVES AROUND THE","Neurotoxicity Abs: ACUTE ORAL TOXICITY IN RATS IS OF HIGH CONCERN. SINGLE ORAL DOSES OF 10-3200 IN 9 RATS WERE ASSOCIATED WITH SIGNS OF NEUROTOXICITY AND MORTALITY TENT WITH AN ORAL LD50 OF 25-50 MG/KG. MORTALITIES OCCURRED FROM 45 S TO 1 DAY FOLLOWING DOSING AND TREATED ANIMALS WERE NOTED TO BE WEAK, , WITH DARK EYES AND/OR WERE OBSERVED TO THROW THEMSELVES AROUND THE"
1576508,Borzelleca et al. 1989,SHORT-TERM TOXICITY (ONE-DAY AND 10-DAY GAVAGE) OF POTASSIUM DICHROMATE IN MALE AND FEMALE RATS,,SHORT-TERM TOXICITY (ONE-DAY AND 10-DAY GAVAGE) OF POTASSIUM DICHROMATE IN MALE AND FEMALE RATS Abs: 
1576507,Jop et al. 1987,COMPARATIVE TOXICITY AND SPECIATION OF 2 HEXAVALENT CHROMIUM SALTS IN ACUTE TOXICITY TESTS,,COMPARATIVE TOXICITY AND SPECIATION OF 2 HEXAVALENT CHROMIUM SALTS IN ACUTE TOXICITY TESTS Abs: 
1576504,Vozmediano et al. 1993,COMPARISON OF TRUE TEST(TM) AND FINN CHAMBERS(R) IN CONSTRUCTION WORKERS,,COMPARISON OF TRUE TEST(TM) AND FINN CHAMBERS(R) IN CONSTRUCTION WORKERS Abs: 
1576503,Rudzki et al. 1976,APPLICATION OF EMULSIFIERS FOR PATCH TEST .1. PATCH TEST WITH POTASSIUM DICHROMATE,,APPLICATION OF EMULSIFIERS FOR PATCH TEST .1. PATCH TEST WITH POTASSIUM DICHROMATE Abs: 
1576502,Owen and  Gawkrodger 1999,Occupational dermatitis in Sheffield: a preliminary study,,Occupational dermatitis in Sheffield: a preliminary study Abs: 
1576500,Mcmahon and  Chen 2008,Perspective of the US Environmental Protection Agency's Office of Pesticide Programs on assessment of dermal sensitization risk using hexavalent chromium as a case study,,Perspective of the US Environmental Protection Agency's Office of Pesticide Programs on assessment of dermal sensitization risk using hexavalent chromium as a case study Abs: 
1576499,Wahlberg 1970,Percutaneous absorption of trivalent and hexavalent chromium (51Cr) through excised human and guinea pig skin,,Percutaneous absorption of trivalent and hexavalent chromium (51Cr) through excised human and guinea pig skin Abs: 
1576498,Van RHEE 1946,"Contact dermatitis, caused by zinc chromate paint",,"Contact dermatitis, caused by zinc chromate paint Abs: "
1576497,Shmunes and  Samitz 1973,Tolerance of hexavalent chromium induced by freund's incomplete adjuvant in guinea pigs,,Tolerance of hexavalent chromium induced by freund's incomplete adjuvant in guinea pigs Abs: 
1576495,Flint et al. 1998,Skin allergy from exposure to alloys of chromium,BIOSIS COPYRIGHT: BIOL ABS. RRM RESEARCH ARTICLE HUMAN HUMAN PATIENT CHROMIUM ALLERGEN SKIN ALLERGY ALLERGY IMMUNE SYSTEM DISEASE INTEGUMENTARY SYSTEM DISEASE,Skin allergy from exposure to alloys of chromium Abs: BIOSIS COPYRIGHT: BIOL ABS. RRM RESEARCH ARTICLE HUMAN HUMAN PATIENT CHROMIUM ALLERGEN SKIN ALLERGY ALLERGY IMMUNE SYSTEM DISEASE INTEGUMENTARY SYSTEM DISEASE
1576494,Burrows et al. 1989,TRIAL OF 0.5-PERCENT VERSUS 0.375-PERCENT POTASSIUM DICHROMATE,,TRIAL OF 0.5-PERCENT VERSUS 0.375-PERCENT POTASSIUM DICHROMATE Abs: 
1576492,Burrows 1997,Metals,"Recent developments and controversies surrounding the allergenicity of gold (7440575), nickel (7440020), chromium (7440473), and palladium (7440053) were reviewed. Recent patch test studies have found that a number of patients reacted positively to routine testing with gold-sodium-thiosulfate (10233882) (GST). This was considered an unusual finding because many of the subjects showed no irritation when wearing gold jewelry or having gold dental fillings. The clinical significance of the positive patch tests for GST is unclear. A number of studies have investigated the possibility that nickel allergy is a risk factor for hand eczema. The studies have not produced conclusive evidence that nickel allergy predisposes to hand dermatitis. A history of atopic dermatitis appears to be a stronger risk factor for hand eczema than nickel allergy. It was noted that if nickel allergy does increase the risk of hand dermatitis, new European legislation which sharply restricts the use of nickel in industrial products and processes should reduce the risk. Recent studies have been conducted to determine the true prevalence of chromate dermatitis. Current reports indicate that on a worldwide basis the prevalence of chromate dermatitis varies from 2% to 25%. This variability probably reflects differences in patient selection for patch testing, type of work occurring in the patient's work area, and interests of the tester. A number of studies have investigated the ability of ferrous-sulfate (7720787) when added to cement to prevent chromate dermatitis in masons and other people who work with cement. The rationale for doing this is that ferrous-sulfate will reduce hexavalent-chromium (18540299) to trivalent-chromium (16065831), which has less potential for dermatitis. The studies showed that in doing this, a considerable decrease in cement dermatitis occurred. A significant number of positive responses to palladium-chloride (7647101) have been observed in routine patch test studies. Since most of the palladium positive subjects also gave positive responses to nickel, this has raised questions about the clinical relevance of the positive responses. Doubts that palladium is a true allergen are reinforced by the finding that patch testing with pure palladium usually produces negative results.","Metals Abs: Recent developments and controversies surrounding the allergenicity of gold (7440575), nickel (7440020), chromium (7440473), and palladium (7440053) were reviewed. Recent patch test studies have found that a number of patients reacted positively to routine testing with gold-sodium-thiosulfate (10233882) (GST). This was considered an unusual finding because many of the subjects showed no irritation when wearing gold jewelry or having gold dental fillings. The clinical significance of the positive patch tests for GST is unclear. A number of studies have investigated the possibility that nickel allergy is a risk factor for hand eczema. The studies have not produced conclusive evidence that nickel allergy predisposes to hand dermatitis. A history of atopic dermatitis appears to be a stronger risk factor for hand eczema than nickel allergy. It was noted that if nickel allergy does increase the risk of hand dermatitis, new European legislation which sharply restricts the use of nickel in industrial products and processes should reduce the risk. Recent studies have been conducted to determine the true prevalence of chromate dermatitis. Current reports indicate that on a worldwide basis the prevalence of chromate dermatitis varies from 2% to 25%. This variability probably reflects differences in patient selection for patch testing, type of work occurring in the patient's work area, and interests of the tester. A number of studies have investigated the ability of ferrous-sulfate (7720787) when added to cement to prevent chromate dermatitis in masons and other people who work with cement. The rationale for doing this is that ferrous-sulfate will reduce hexavalent-chromium (18540299) to trivalent-chromium (16065831), which has less potential for dermatitis. The studies showed that in doing this, a considerable decrease in cement dermatitis occurred. A significant number of positive responses to palladium-chloride (7647101) have been observed in routine patch test studies. Since most of the palladium positive subjects also gave positive responses to nickel, this has raised questions about the clinical relevance of the positive responses. Doubts that palladium is a true allergen are reinforced by the finding that patch testing with pure palladium usually produces negative results."
1576489,White and  Rasmussen 1996,"SOS Chromotest results in a broader context: Empirical relationships between genotoxic potency, mutagenic potency, and carcinogenic potency",,"SOS Chromotest results in a broader context: Empirical relationships between genotoxic potency, mutagenic potency, and carcinogenic potency Abs: "
1576487,Unceta et al. 2010,Chromium speciation in solid matrices and regulation: a review,,Chromium speciation in solid matrices and regulation: a review Abs: 
1576486,Sugiyama 1992,Role of physiological antioxidants in chromium(VI)-induced cellular injury,"BIOSIS COPYRIGHT: BIOL ABS. Chromium(VI) compounds are well known to be potent toxic and carcinogenic agents. Because chromium(VI) is easily taken up by cells and is subsequently reduced to the trivalent form, the formation of chronium(III) or other intermediate oxidation states such as chromium(V) and (IV) is believed to a play a role in the adverse biological effects of chromium(VI) compounds. Recent in vitro studies have shown that this reduction process generates free radical species such as active oxygen radicals. Furthermore, physiological antioxidants are reported to modify the genotoxic and toxic effects of chromate. This article reviewed the recent in vitro and in vivo studies of the effects of antioxidants including active oxygen scavengers; glutathione; vitamins B2, E, and C, on chromate-induced injury such as DNA lesions; lipid peroxidation; enzyme inhibition; cytotoxicity; mutation; and so on. In addition, the mechanism of action of these antioxidants was discussed with respect to the","Role of physiological antioxidants in chromium(VI)-induced cellular injury Abs: BIOSIS COPYRIGHT: BIOL ABS. Chromium(VI) compounds are well known to be potent toxic and carcinogenic agents. Because chromium(VI) is easily taken up by cells and is subsequently reduced to the trivalent form, the formation of chronium(III) or other intermediate oxidation states such as chromium(V) and (IV) is believed to a play a role in the adverse biological effects of chromium(VI) compounds. Recent in vitro studies have shown that this reduction process generates free radical species such as active oxygen radicals. Furthermore, physiological antioxidants are reported to modify the genotoxic and toxic effects of chromate. This article reviewed the recent in vitro and in vivo studies of the effects of antioxidants including active oxygen scavengers; glutathione; vitamins B2, E, and C, on chromate-induced injury such as DNA lesions; lipid peroxidation; enzyme inhibition; cytotoxicity; mutation; and so on. In addition, the mechanism of action of these antioxidants was discussed with respect to the"
1576485,Wo?niak 1996,[Molecular effects of chromium compound activity],"Chromium(VI) compounds produce a variety of DNA damage such as DNA single strand breaks, alkali-labile sites and DNA-protein cross-links in vivo and in cultured cells. Chromium(III) compounds bound to isolated DNA and proteins. Cr(VI) readily entered cell through general anion channels. In contrast, Cr(III) did not readily cross cell membranes. Inside cells Cr(VI) is reduced through intermediates to Cr(III) by cellular reductants. Reactive intermediates formed during intracellular Cr(VI) reduction might be responsible for some chromate genotoxicity. Ascorbic acid decreases chromate induced alkali-labile sites and chromium inhibition of glutathione reductase, but it enhances DNA-protein cross-links and cytotoxicity caused by this metal.","[Molecular effects of chromium compound activity] Abs: Chromium(VI) compounds produce a variety of DNA damage such as DNA single strand breaks, alkali-labile sites and DNA-protein cross-links in vivo and in cultured cells. Chromium(III) compounds bound to isolated DNA and proteins. Cr(VI) readily entered cell through general anion channels. In contrast, Cr(III) did not readily cross cell membranes. Inside cells Cr(VI) is reduced through intermediates to Cr(III) by cellular reductants. Reactive intermediates formed during intracellular Cr(VI) reduction might be responsible for some chromate genotoxicity. Ascorbic acid decreases chromate induced alkali-labile sites and chromium inhibition of glutathione reductase, but it enhances DNA-protein cross-links and cytotoxicity caused by this metal."
1576484,Kortenkamp 1997,Problems in the biological monitoring of chromium(VI) exposed individuals,"The usefulness of currently available techniques for the biological monitoring of chromium(VI) exposed individuals is reviewed. Chromium levels in body fluids, such as urine and blood plasma, are reliable markers of exposure to chromium in oxidation states (VI) and (III) and provide a measure of the internalized dose of chromium. These markers are sufficiently sensitive to be useful in most occupational settings encountered today. In contrast, the majority of cytogenetic surveillance studies among chromium platers, ferrochromium workers and stainless steel welders using the manual metal arc (MMA) method have yielded negative or inconclusive results. As a marker for genotoxicity, the number of sister chromatid exchanges in blood lymphocytes proved to be relatively insensitive towards exposure to chromium(VI). There were however significant increases in rare chromosome aberrations among MMA stainless steel welders, although the reported levels of all aberrations combined were similar to those observed among control groups of many other studies. The relative lack of success of cytogenetic surveillance studies using blood lymphocytes is surprising in view of the strong genotoxicity of chromium(VI). A possible explanation comes from recent studies which showed that the differences in chromium lymphocyte levels between exposed and controls were disproportionately small. Another factor which complicates attempts to correlate genotoxic effects in lymphocytes with the processes giving rise to cancers of the respiratory system is the toxicokinetics of inhaled chromium(VI). Only small fractions of the total inhaled dose are distributed in the body while the bulk of chromium(VI) deposited in the lungs remains there for very long periods of time. The vast majority of lymphocytes will therefore come into contact with chromium(VI) not while travelling through the supporting tissues of the lungs but during their migration through the blood. There they take up chromium(VI) that has leached from the lungs. Blood lymphocytes therefore seem to be inappropriate for the monitoring of the biologically effective dose, and of early biological effects arising from exposure to chromium(VI). Thus there is an urgent need to develop techniques which would allow the non-invasive monitoring of internalized doses of chromium in the lung.","Problems in the biological monitoring of chromium(VI) exposed individuals Abs: The usefulness of currently available techniques for the biological monitoring of chromium(VI) exposed individuals is reviewed. Chromium levels in body fluids, such as urine and blood plasma, are reliable markers of exposure to chromium in oxidation states (VI) and (III) and provide a measure of the internalized dose of chromium. These markers are sufficiently sensitive to be useful in most occupational settings encountered today. In contrast, the majority of cytogenetic surveillance studies among chromium platers, ferrochromium workers and stainless steel welders using the manual metal arc (MMA) method have yielded negative or inconclusive results. As a marker for genotoxicity, the number of sister chromatid exchanges in blood lymphocytes proved to be relatively insensitive towards exposure to chromium(VI). There were however significant increases in rare chromosome aberrations among MMA stainless steel welders, although the reported levels of all aberrations combined were similar to those observed among control groups of many other studies. The relative lack of success of cytogenetic surveillance studies using blood lymphocytes is surprising in view of the strong genotoxicity of chromium(VI). A possible explanation comes from recent studies which showed that the differences in chromium lymphocyte levels between exposed and controls were disproportionately small. Another factor which complicates attempts to correlate genotoxic effects in lymphocytes with the processes giving rise to cancers of the respiratory system is the toxicokinetics of inhaled chromium(VI). Only small fractions of the total inhaled dose are distributed in the body while the bulk of chromium(VI) deposited in the lungs remains there for very long periods of time. The vast majority of lymphocytes will therefore come into contact with chromium(VI) not while travelling through the supporting tissues of the lungs but during their migration through the blood. There they take up chromium(VI) that has leached from the lungs. Blood lymphocytes therefore seem to be inappropriate for the monitoring of the biologically effective dose, and of early biological effects arising from exposure to chromium(VI). Thus there is an urgent need to develop techniques which would allow the non-invasive monitoring of internalized doses of chromium in the lung."
1576483,Kimura 2010,Molecular Mechanisms of Zinc-mediated Induction and Chromium(VI)-mediated Inhibition of Mouse Metallothionein-I Gene Transcription,,Molecular Mechanisms of Zinc-mediated Induction and Chromium(VI)-mediated Inhibition of Mouse Metallothionein-I Gene Transcription Abs: 
1576482,Pawlisz et al. 1997,Canadian water quality guidelines for chromium,"BIOSIS COPYRIGHT: BIOL ABS. Canadian Water Quality Guidelines (CWQG) are numerical or narrative limits that protect designated water uses. Development of CWQG is based on review of chromium's properties, uses, fate in the environment, ambient levels, accumulation in biota, and toxicity. Chromium's principal uses and entry into the environment include electroplating, production of paints and pigments, tanning, wood preservation, chromium chemicals production, metal smelting, and pulp and paper production. Concentrations of chromium in Canada range between 1 and 545,000 ng m-3 in air, 0.001 and 0.165 mg L-1 in water, nondetectable and 31,000 mg kg-1 in sediments, 10 and 5000 mg kg-1 in soils, 0.006 and 18 mg kg-1 in plants, and 0.03 and 1.6 mg kg-1 in animals. In nature, trivalent chromium sorbs to various ligands and forms insoluble entities becoming unavailable for uptake by biota. Hexavalent chromium forms many soluble salts that can enter body membranes and induce a toxic response. Estimates of","Canadian water quality guidelines for chromium Abs: BIOSIS COPYRIGHT: BIOL ABS. Canadian Water Quality Guidelines (CWQG) are numerical or narrative limits that protect designated water uses. Development of CWQG is based on review of chromium's properties, uses, fate in the environment, ambient levels, accumulation in biota, and toxicity. Chromium's principal uses and entry into the environment include electroplating, production of paints and pigments, tanning, wood preservation, chromium chemicals production, metal smelting, and pulp and paper production. Concentrations of chromium in Canada range between 1 and 545,000 ng m-3 in air, 0.001 and 0.165 mg L-1 in water, nondetectable and 31,000 mg kg-1 in sediments, 10 and 5000 mg kg-1 in soils, 0.006 and 18 mg kg-1 in plants, and 0.03 and 1.6 mg kg-1 in animals. In nature, trivalent chromium sorbs to various ligands and forms insoluble entities becoming unavailable for uptake by biota. Hexavalent chromium forms many soluble salts that can enter body membranes and induce a toxic response. Estimates of"
1576481,Kimura 2007,[Molecular mechanism involved in chromium(VI) toxicity],"Chromium exists in many different oxidation states in the environment, Cr(VI) and Cr(III) being the most stable forms. Chromium has been known for over 100 years to be a human carcinogen. The greatest risk of cancer from chromium exposure is associated with Cr(VI). Cr(VI) enters cells via the sulfate anion transporter system and is reduced to intermediate oxidation states, such as Cr(V) and Cr(IV), in the process of forming stable Cr(III) forms. It is known that Cr(VI) affects expression of various genes. Metal responsive element-binding transcription factor-1 (MTF-1) is involved in sensing heavy metal load and the induced transcription of several protective genes, including metallothionein (MT)-I, MT-II, zinc transporter-1, and gamma-glutamylcysteine synthetase. Cr(VI) inhibits zinc-induced MT transcription via modifying transactivation potential of MTF-1. However, the molecular mechanism for the Cr(VI)-mediated inhibition of MTF-1 has not been fully elucidated. In this review, I briefly summarize the previous studies and discuss the current status of research on Cr(VI) toxicity and Cr(VI)-mediated inhibition against transcription.","[Molecular mechanism involved in chromium(VI) toxicity] Abs: Chromium exists in many different oxidation states in the environment, Cr(VI) and Cr(III) being the most stable forms. Chromium has been known for over 100 years to be a human carcinogen. The greatest risk of cancer from chromium exposure is associated with Cr(VI). Cr(VI) enters cells via the sulfate anion transporter system and is reduced to intermediate oxidation states, such as Cr(V) and Cr(IV), in the process of forming stable Cr(III) forms. It is known that Cr(VI) affects expression of various genes. Metal responsive element-binding transcription factor-1 (MTF-1) is involved in sensing heavy metal load and the induced transcription of several protective genes, including metallothionein (MT)-I, MT-II, zinc transporter-1, and gamma-glutamylcysteine synthetase. Cr(VI) inhibits zinc-induced MT transcription via modifying transactivation potential of MTF-1. However, the molecular mechanism for the Cr(VI)-mediated inhibition of MTF-1 has not been fully elucidated. In this review, I briefly summarize the previous studies and discuss the current status of research on Cr(VI) toxicity and Cr(VI)-mediated inhibition against transcription."
1576480,Kanerva and  Aitio 1997,Dermatotoxicological aspects of metallic chromium,,Dermatotoxicological aspects of metallic chromium Abs: 
1576477,Flynn and  Susi 2012,Local exhaust ventilation for the control of welding fumes in the construction industry--a literature review,"Arc welding is a common unit operation in the construction industry, where frequent changes in location and welding position make it more difficult to control fume exposures than in industries where fixed locations are the norm. Welders may be exposed to a variety of toxic airborne contaminants including manganese (Mn) and hexavalent chromium (CrVI). Local exhaust ventilation (LEV) is a well-known engineering control for welding fumes but has not been adopted widely in the construction industry. This literature review presents data on the performance of a variety of LEV systems for welding fume control from the construction (five references), shipyard (five references), and other industries. The studies indicate that LEV can reduce fume exposures to total particulate, Mn, and CrVI to levels below currently relevant standards. Field studies suggest that 40-50% or more reduction in exposure is possible with portable or fixed LEV systems relative to natural ventilation but that correct positioning of the hood and adequate exhaust flow rates are essential. Successful implementation of extraction guns for gas metal arc welding (GMAW) and flux core arc welding has been demonstrated, indicating that a successful balance between extraction airflow and shielding gas requirements is possible. Work practices are an important part of achieving successful control of fume exposures; in particular, positioning the hood close to the arc, checking exhaust flow rates, and avoiding the plume. Further research is needed on hood size effects for controlling welding fume with portable LEV systems and identifying and overcoming barriers to LEV use in construction.","Local exhaust ventilation for the control of welding fumes in the construction industry--a literature review Abs: Arc welding is a common unit operation in the construction industry, where frequent changes in location and welding position make it more difficult to control fume exposures than in industries where fixed locations are the norm. Welders may be exposed to a variety of toxic airborne contaminants including manganese (Mn) and hexavalent chromium (CrVI). Local exhaust ventilation (LEV) is a well-known engineering control for welding fumes but has not been adopted widely in the construction industry. This literature review presents data on the performance of a variety of LEV systems for welding fume control from the construction (five references), shipyard (five references), and other industries. The studies indicate that LEV can reduce fume exposures to total particulate, Mn, and CrVI to levels below currently relevant standards. Field studies suggest that 40-50% or more reduction in exposure is possible with portable or fixed LEV systems relative to natural ventilation but that correct positioning of the hood and adequate exhaust flow rates are essential. Successful implementation of extraction guns for gas metal arc welding (GMAW) and flux core arc welding has been demonstrated, indicating that a successful balance between extraction airflow and shielding gas requirements is possible. Work practices are an important part of achieving successful control of fume exposures; in particular, positioning the hood close to the arc, checking exhaust flow rates, and avoiding the plume. Further research is needed on hood size effects for controlling welding fume with portable LEV systems and identifying and overcoming barriers to LEV use in construction."
1576476,Dubois and  Belleville 1991,[Chromium: physiologic role and implications in human pathology],"Reported values for total body stores of chromium vary between 0.4 mg and 6 mg. Chromium stores may be higher in neonates than in adults, relative to body size, whereas tissular chromium may be depleted in the elderly. The recommended daily allowance for chromium is 50 to 200 micrograms/day but actual needs are poorly known. Digestive absorption is better for organic chromium, which is part of the &quot;glucose tolerance factor&quot; (GTF), than for inorganic chromium. Furthermore, chromium (VI) is better absorbed than chromium (III). In the body, chromium (VI) is rapidly reduced to chromium (III) by a number of metabolic pathways. Absorbed chromium binds to proteins, mainly to transferrin which exhibits a high affinity for chromium (III). Most absorbed chromium is eliminated through the kidneys. Renal excretion occurs according to a two or more-compartment model. Current methods used to assay chromium, i.e., atomic absorption spectrometry using a graphite furnace or neutron activation, are sufficiently sensitive and specific to evaluate chromium levels in blood, urine or hair. However, none of these levels accurately reflects chromium body stores. Chromium is part of the GTF molecule. This factor has no effect per se but may facilitate binding of insulin to insulin receptors and amplify the effects of insulin on carbohydrate and lipid metabolism. Chromium deficiency may play a role in a development of some forms of adult diabetes mellitus and of arteriosclerosis. Partial chromium deficiencies seem to be common, especially in individuals with high intakes of refined foods. Acute chromium poisoning is usually due to an excess of chromium (VI) and is sometimes seen in the chromium industry.(ABSTRACT TRUNCATED AT 250 WORDS)","[Chromium: physiologic role and implications in human pathology] Abs: Reported values for total body stores of chromium vary between 0.4 mg and 6 mg. Chromium stores may be higher in neonates than in adults, relative to body size, whereas tissular chromium may be depleted in the elderly. The recommended daily allowance for chromium is 50 to 200 micrograms/day but actual needs are poorly known. Digestive absorption is better for organic chromium, which is part of the &quot;glucose tolerance factor&quot; (GTF), than for inorganic chromium. Furthermore, chromium (VI) is better absorbed than chromium (III). In the body, chromium (VI) is rapidly reduced to chromium (III) by a number of metabolic pathways. Absorbed chromium binds to proteins, mainly to transferrin which exhibits a high affinity for chromium (III). Most absorbed chromium is eliminated through the kidneys. Renal excretion occurs according to a two or more-compartment model. Current methods used to assay chromium, i.e., atomic absorption spectrometry using a graphite furnace or neutron activation, are sufficiently sensitive and specific to evaluate chromium levels in blood, urine or hair. However, none of these levels accurately reflects chromium body stores. Chromium is part of the GTF molecule. This factor has no effect per se but may facilitate binding of insulin to insulin receptors and amplify the effects of insulin on carbohydrate and lipid metabolism. Chromium deficiency may play a role in a development of some forms of adult diabetes mellitus and of arteriosclerosis. Partial chromium deficiencies seem to be common, especially in individuals with high intakes of refined foods. Acute chromium poisoning is usually due to an excess of chromium (VI) and is sometimes seen in the chromium industry.(ABSTRACT TRUNCATED AT 250 WORDS)"
1576475,Chiu et al. 1998,Activation of a procarcinogen by reduction: Cr6+-> Cr5+-> Cr4+-> Cr3+ a case study by electron spin resonance (ESR/PMR),,Activation of a procarcinogen by reduction: Cr6+-> Cr5+-> Cr4+-> Cr3+ a case study by electron spin resonance (ESR/PMR) Abs: 
1576474,Babu et al. 2009,Waste Minimization in Electroplating Industries: A Review,,Waste Minimization in Electroplating Industries: A Review Abs: 
1576473,Fernandes et al. 2002,Chromium interference with mitochondrial bioenergetics,"The mechanism of Cr(VI)-induced toxicity in plants and animals was studied for mitochondrial bioenergetics in turnip root and rat liver mitochondria. Chromium(VI) interference with mitochondrial bionergetics of plant and animal mitochondria was shown by decrease of the succinate-dependent respiratory indexes, (RCR and ADP/O); alterations on oxygen-supported respiration by succinate on state 4, state 3 and uncoupled respiration with parallel AT dissipation and decrease of the phosphorylation efficiency; inhibition of the NADH-ubiquinone oxidoreductase (complex I) and succinate-dehydrogenase (complex II); alterations on the mitochondrial ATPase activity (complex V); and membrane permeabilization to K(+). Although Cr(VI) interferes with mitochondrial bionergetics of both plant and animal mitochondria, differences on the sensitivity to Cr(VI), AT and phosphorylation efficiency, state 4 respiration and ATPase activities, and K(+) influx were detected between them. In conclusion, CrVI)-induced perturbations on mitochondrial bioenergetics may contribute to the basal mechanism underlying its toxic effects in plant and animal cells.","Chromium interference with mitochondrial bioenergetics Abs: The mechanism of Cr(VI)-induced toxicity in plants and animals was studied for mitochondrial bioenergetics in turnip root and rat liver mitochondria. Chromium(VI) interference with mitochondrial bionergetics of plant and animal mitochondria was shown by decrease of the succinate-dependent respiratory indexes, (RCR and ADP/O); alterations on oxygen-supported respiration by succinate on state 4, state 3 and uncoupled respiration with parallel AT dissipation and decrease of the phosphorylation efficiency; inhibition of the NADH-ubiquinone oxidoreductase (complex I) and succinate-dehydrogenase (complex II); alterations on the mitochondrial ATPase activity (complex V); and membrane permeabilization to K(+). Although Cr(VI) interferes with mitochondrial bionergetics of both plant and animal mitochondria, differences on the sensitivity to Cr(VI), AT and phosphorylation efficiency, state 4 respiration and ATPase activities, and K(+) influx were detected between them. In conclusion, CrVI)-induced perturbations on mitochondrial bioenergetics may contribute to the basal mechanism underlying its toxic effects in plant and animal cells."
1576472,DuPont 1992,2-year carcinogenicity study in rats by implanted pellet,,2-year carcinogenicity study in rats by implanted pellet Abs: 
1576469,Wolf and  Ottenwälder 1989,Detection of DNA strand breaks induced by different chromium species in PBR 322 using nick translation,,Detection of DNA strand breaks induced by different chromium species in PBR 322 using nick translation Abs: 
1576468,Yonaha et al. 1980,Effects of trivalent and hexavalent chromium on lipid peroxidation in rat liver microsomes,,Effects of trivalent and hexavalent chromium on lipid peroxidation in rat liver microsomes Abs: 
1576467,White et al. 1981,RESPONSE OF A HUMAN-TUMOR CELL-LINE TO CHRONIC POTASSIUM DICHROMATE EXPOSURE,,RESPONSE OF A HUMAN-TUMOR CELL-LINE TO CHRONIC POTASSIUM DICHROMATE EXPOSURE Abs: 
1576466,Trzeciak et al. 1999,Genotoxicity of chromium in human gastric mucosa cells and peripheral blood lymphocytes,,Genotoxicity of chromium in human gastric mucosa cells and peripheral blood lymphocytes Abs: 
1576465,Rao et al. 1999,Genotoxic effects of potassium dichromate in human blood cultures,,Genotoxic effects of potassium dichromate in human blood cultures Abs: 
1576463,Sugiyama et al. 1989,Vitamin B2-enhancement of sodium chromate (VI)--Induced DNA single strand breaks: ESR study of the action of vitamin B2,"Incubation of Chinese hamster V-79 cells with Na2CrO4 plus vitamin B2 resulted in an increase of Na2CrO4-induced DNA single strand breaks. Electron spin resonance (ESR) studies showed that vitamin B2 enhanced the formation of both hydroxyl radical and tetraperoxochromate (V) during the reaction of Na2CrO4 with hydrogen peroxide. Furthermore, ESR studies demonstrated that a chromium (V) species with a g value of 1.977 was formed by the reaction of Na2CrO4 with vitamin B2. These results indicate that chromate reacts with vitamin B2 to form chromium (V) species and also suggest that the enhancement effect of vitamin B2 on chromate-induced DNA single strand breaks may result from an increase of chromium (V)-related hydroxyl radical formation.","Vitamin B2-enhancement of sodium chromate (VI)--Induced DNA single strand breaks: ESR study of the action of vitamin B2 Abs: Incubation of Chinese hamster V-79 cells with Na2CrO4 plus vitamin B2 resulted in an increase of Na2CrO4-induced DNA single strand breaks. Electron spin resonance (ESR) studies showed that vitamin B2 enhanced the formation of both hydroxyl radical and tetraperoxochromate (V) during the reaction of Na2CrO4 with hydrogen peroxide. Furthermore, ESR studies demonstrated that a chromium (V) species with a g value of 1.977 was formed by the reaction of Na2CrO4 with vitamin B2. These results indicate that chromate reacts with vitamin B2 to form chromium (V) species and also suggest that the enhancement effect of vitamin B2 on chromate-induced DNA single strand breaks may result from an increase of chromium (V)-related hydroxyl radical formation."
1576462,Stern et al. 1982,Origin of mutagenicity of welding fumes in S. typhimurium,"The origin of mutagenicity in S. typhimurium in response to exposure to welding fumes, a complex mixture of metallic oxides and other inorganic compounds, was studied through the quantitative use of the histidine revertant Salmonella microsome test of Ames. Dose-response experiments and factorial design studies independently showed the mutagenic activity to be due to the presence of soluble Cr(VI). A rate of 65 ± 15 revertants per plate per ?g Cr(VI) was found for all fumes produced by the metal inert gas welding of stainless steel. A significantly reduced rate was found for manual metal arc welding fumes. The presence of other metals in low oxidation states (e.g. Fe(0), Fe(II), Al(0)), results in a significant reduction of the Cr(VI), accompanied by a corresponding decrease of the absolute revertant rate per unit fume mass.","Origin of mutagenicity of welding fumes in S. typhimurium Abs: The origin of mutagenicity in S. typhimurium in response to exposure to welding fumes, a complex mixture of metallic oxides and other inorganic compounds, was studied through the quantitative use of the histidine revertant Salmonella microsome test of Ames. Dose-response experiments and factorial design studies independently showed the mutagenic activity to be due to the presence of soluble Cr(VI). A rate of 65 ± 15 revertants per plate per ?g Cr(VI) was found for all fumes produced by the metal inert gas welding of stainless steel. A significantly reduced rate was found for manual metal arc welding fumes. The presence of other metals in low oxidation states (e.g. Fe(0), Fe(II), Al(0)), results in a significant reduction of the Cr(VI), accompanied by a corresponding decrease of the absolute revertant rate per unit fume mass."
1576461,Rudnykh and  Zasukhina 1985,DNA repair synthesis in lymphocytes of people contacting chromium compounds in industry,,DNA repair synthesis in lymphocytes of people contacting chromium compounds in industry Abs: 
1576460,Mclean et al. 2012,"Hexavalent chromium review, part 1: Health effects, regulations, and analysis",,"Hexavalent chromium review, part 1: Health effects, regulations, and analysis Abs: "
1576459,Mahmood et al. 2008,Hexavalent chromium toxicity in pituitary and thyroid glands,,Hexavalent chromium toxicity in pituitary and thyroid glands Abs: 
1576457,Merlini et al. 1985,THE CULTURED MOUSE EMBRYO AS A MODEL FOR THE EVALUATION OF PHYSICAL AND CHEMICAL TOXICITY,,THE CULTURED MOUSE EMBRYO AS A MODEL FOR THE EVALUATION OF PHYSICAL AND CHEMICAL TOXICITY Abs: 
1576456,Majone 1977,Mitotic alterations induced by chromium VI and chromium III on human cells in-vitro,,Mitotic alterations induced by chromium VI and chromium III on human cells in-vitro Abs: 
1576454,Laj et al. 1984,Comparative toxicity of trivalent and hexavalent chromium: 4: Biochemical-changes in blood and liver of rat,,Comparative toxicity of trivalent and hexavalent chromium: 4: Biochemical-changes in blood and liver of rat Abs: 
1576453,Klein et al. 2003,Total chromium concentration in natural oak wood used for a dust inhalation study in rats,,Total chromium concentration in natural oak wood used for a dust inhalation study in rats Abs: 
1576450,Iero et al. 2010,Interactions of Cr(VI) and Cr(III) with isolated rat liver mitochondria,,Interactions of Cr(VI) and Cr(III) with isolated rat liver mitochondria Abs: 
1576448,Hildebrand et al. 1986,Cytotoxic effects of welding fumes on human embryonic epithelial pulmonary cells in culture,"Certain welding fumes contain significant amounts of Cr, Mn, Ni and trances of other metals, which were shown to be mutagenic in one or more in vitro bioassays. Some of these metals are strongly suspected human carcinogens, and it might, therefore be expected that welders experience an excess risk of respiratory tract cancer because of their occupation. The toxic effect of two MIG/55 and one MMA/SS welding fumes were studies on human embryonic epithelial pulmonary cells in culture (Ll32). (Copyright (c) The Danish Welding Institute Copenhagen 1985).","Cytotoxic effects of welding fumes on human embryonic epithelial pulmonary cells in culture Abs: Certain welding fumes contain significant amounts of Cr, Mn, Ni and trances of other metals, which were shown to be mutagenic in one or more in vitro bioassays. Some of these metals are strongly suspected human carcinogens, and it might, therefore be expected that welders experience an excess risk of respiratory tract cancer because of their occupation. The toxic effect of two MIG/55 and one MMA/SS welding fumes were studies on human embryonic epithelial pulmonary cells in culture (Ll32). (Copyright (c) The Danish Welding Institute Copenhagen 1985)."
1576447,Hamilton and  Wetterhahn 1986,Chromium-induced DNA damage in vivo in the chick embryo,,Chromium-induced DNA damage in vivo in the chick embryo Abs: 
1576446,Gunaratnam and  Grant 2001,Glutathione reductase reduces chromium VI to cytotoxic metabolites in isolated rat hepatocytes,,Glutathione reductase reduces chromium VI to cytotoxic metabolites in isolated rat hepatocytes Abs: 
1576445,Galli et al. 1988,Nitrilotriacetic acid effect on the genetic activity induced by chromium chloride and sodium chromate in Saccharomyces cerevisiae,"The influence of nitrilotriacetic acid (NTA), a substitute of poliphosphates in laundry detergents, on mitotic gene conversion and point reverse mutation induced by sodium chromate and chromium chloride was analyzed on D7 strain of Saccharomyces cerevisiae. NTA determined a significant decrease of chromate convertogenic activity while the induced point reverse mutation was not affected. This can be due to a direct interaction between chromate and NTA or to a possible NTA effect on recombinational repair of DNA?breaks induced by the chromate oxidizing activity. Both chromium chloride and NTA dissolved into liquid growth medium inhibited cell growth but the simultaneous presence of both compounds allowed cells to grow. In this condition the cell population, growing up to the stationary phase, accumulated a significant number of convertants and revertants. Our results indicate that NTA, interacting with Cr3+ , probably forms NTA?Cr3+ complexes able to cross the membranes and to react with DNA. In addition the present work confirmed the NTA genetic inactivity on yeast system.","Nitrilotriacetic acid effect on the genetic activity induced by chromium chloride and sodium chromate in Saccharomyces cerevisiae Abs: The influence of nitrilotriacetic acid (NTA), a substitute of poliphosphates in laundry detergents, on mitotic gene conversion and point reverse mutation induced by sodium chromate and chromium chloride was analyzed on D7 strain of Saccharomyces cerevisiae. NTA determined a significant decrease of chromate convertogenic activity while the induced point reverse mutation was not affected. This can be due to a direct interaction between chromate and NTA or to a possible NTA effect on recombinational repair of DNA?breaks induced by the chromate oxidizing activity. Both chromium chloride and NTA dissolved into liquid growth medium inhibited cell growth but the simultaneous presence of both compounds allowed cells to grow. In this condition the cell population, growing up to the stationary phase, accumulated a significant number of convertants and revertants. Our results indicate that NTA, interacting with Cr3+ , probably forms NTA?Cr3+ complexes able to cross the membranes and to react with DNA. In addition the present work confirmed the NTA genetic inactivity on yeast system."
1576442,Corbett et al. 1970,Attempts to correlate carcinogenic with mutagenic activity using bacteriophage T4,,Attempts to correlate carcinogenic with mutagenic activity using bacteriophage T4 Abs: 
1576441,Grogan and  Oppenheimer 1955,Experimental studies in metal cancerigenesis. V. Interaction of CrIII and CrVI compounds with proteins,,Experimental studies in metal cancerigenesis. V. Interaction of CrIII and CrVI compounds with proteins Abs: 
1576439,Avdic et al. 1986,THE INFLUENCE OF (III AND VI) CHROMIUM AND ZINC ON LACTATE-DEHYDROGENASE ACTIVITY IN RATS,,THE INFLUENCE OF (III AND VI) CHROMIUM AND ZINC ON LACTATE-DEHYDROGENASE ACTIVITY IN RATS Abs: 
1576435,Bolt et al. 1989,Interaction of different chromium species with dna and nucleotides,,Interaction of different chromium species with dna and nucleotides Abs: 
1576408,Foster 1995,Treatment of Plastic Media Waste,"In AGARD, Environmentally Safe and Effective Processes for Paint Removal 1 p. gh plastic media itself is not generally considered a hazardous waste, the paint particles containing chromate pigments contaminating the spent media are considered a hazardous waste product. There are currently four approaches under investigation aiming to reduce the volume of hazardous waste produced during paint stripping: elimination of the chromate containing pigments or other hazardous pigments from primers and coatings; separation of the paint or hazardous materials from the plastic or other media; encapsulation or recycling of the contaminated media to make it safe for disposal or reuse; and produce a biodegradable media. Research to develop new pigments and primers that will result in the elimination of hazardous pigments such as strontium chromate and in developing alternative anti-corrosive surface treatments to replace cadmium plating is continuing. Contamination of the spent media will remain a problem because the hazardous pigments and surface treatments will still be used on aircraft and their components for the foreseeable future. Therefore, the only realistic alternatives at the moment to reduce the volume of hazardous waste produced by PMB (plastic media blasting) are to recycle or re-use the media in some form or remove the hazardous materials from the media.","Treatment of Plastic Media Waste Abs: In AGARD, Environmentally Safe and Effective Processes for Paint Removal 1 p. gh plastic media itself is not generally considered a hazardous waste, the paint particles containing chromate pigments contaminating the spent media are considered a hazardous waste product. There are currently four approaches under investigation aiming to reduce the volume of hazardous waste produced during paint stripping: elimination of the chromate containing pigments or other hazardous pigments from primers and coatings; separation of the paint or hazardous materials from the plastic or other media; encapsulation or recycling of the contaminated media to make it safe for disposal or reuse; and produce a biodegradable media. Research to develop new pigments and primers that will result in the elimination of hazardous pigments such as strontium chromate and in developing alternative anti-corrosive surface treatments to replace cadmium plating is continuing. Contamination of the spent media will remain a problem because the hazardous pigments and surface treatments will still be used on aircraft and their components for the foreseeable future. Therefore, the only realistic alternatives at the moment to reduce the volume of hazardous waste produced by PMB (plastic media blasting) are to recycle or re-use the media in some form or remove the hazardous materials from the media."
1576406,DuPont 1992,Initial Submission: Letter from Dupont Chem to USEPA Regarding a Chromium Report with Cover Letter and Attachments,,Initial Submission: Letter from Dupont Chem to USEPA Regarding a Chromium Report with Cover Letter and Attachments Abs: 
1576401,Ciba-Geigy 1983,Letter from CIBA-GEIGY corporation to USEPA submitting preliminary test results on strontium chromate with attachments,This brief interim report has been produced in an attempt to collate information regarding the significant number of lung lesions that have occurred in certain treatment groups over the past few months. The overall pattern of survival and probable causes of death or ill-health in the animals autopsied up to 28th September 1979 is shown in Table 1A. These animals (with the exception of the positive control group 23) received their pellets during the period April-August 1978 and thus the youngest of these animals has been under study for just over one year.,Letter from CIBA-GEIGY corporation to USEPA submitting preliminary test results on strontium chromate with attachments Abs: This brief interim report has been produced in an attempt to collate information regarding the significant number of lung lesions that have occurred in certain treatment groups over the past few months. The overall pattern of survival and probable causes of death or ill-health in the animals autopsied up to 28th September 1979 is shown in Table 1A. These animals (with the exception of the positive control group 23) received their pellets during the period April-August 1978 and thus the youngest of these animals has been under study for just over one year.
1576399,Ciba-Geigy 1979,Letter from CIBA-GEIGY Corporation to USEPA Submitting Preliminary Test Results on Strontium Chromate with Attachments,This brief interim report has been produced in an attempt to collate information regarding the significant number of lung lesions that have occurred in certain treatment groups over the past few months. The overall pattern of survival and probable causes of death or ill-health in the animals autopsied up to 28th September 1979 is shown in Table 1A. These animals (with the exception of the positive control group 23) received their pellets during the period April-August 1978 and thus the youngest of these animals has been under study for just over one year.,Letter from CIBA-GEIGY Corporation to USEPA Submitting Preliminary Test Results on Strontium Chromate with Attachments Abs: This brief interim report has been produced in an attempt to collate information regarding the significant number of lung lesions that have occurred in certain treatment groups over the past few months. The overall pattern of survival and probable causes of death or ill-health in the animals autopsied up to 28th September 1979 is shown in Table 1A. These animals (with the exception of the positive control group 23) received their pellets during the period April-August 1978 and thus the youngest of these animals has been under study for just over one year.
1576398,Allied Chemical Corporation 1978,Epidemiology,,Epidemiology Abs: 
1576387,Wise and  Wise 2011,Untitled,,Untitled Abs: 
1576386,Wise and  Wise 2005,"Mutation research, genetic toxicology and environmental mutagenesis",,"Mutation research, genetic toxicology and environmental mutagenesis Abs: "
1576384,Tisher et al. 1970,An ultrastructural and histochenical investigation of potassium dichromate- induced cellular injury in single microperfused renal tubes,,An ultrastructural and histochenical investigation of potassium dichromate- induced cellular injury in single microperfused renal tubes Abs: 
1576383,Shepherd and  Jones 1970,Hexavalent chromium: Toxicological effects and means for removal from aqueous solution,,Hexavalent chromium: Toxicological effects and means for removal from aqueous solution Abs: 
1576374,O'Brien and  Kortenkamp 1995,The chemistry underlying chromate toxicity,,The chemistry underlying chromate toxicity Abs: 
1576373,Mccarty 1996,Chromium(III) picolinate,,Chromium(III) picolinate Abs: 
1576372,Manning and  Patierno 1996,Apoptosis: Inhibitor or instigator of carcinogenesis?,"Carcinogenesis is considered to require an initiating event that results in an irreversible genetic change in a subpopulation of cells. Based on the available evidence, it seems likely that apoptosis may act to attenuate this process by causing the deletion of genetically damaged cells from the host organism. Nevertheless, the existence of an active pathway leading to apoptotic cell death may be a double-edged sword, simply because it can be overcome. Some cells may exhibit preexisting genetic or epigenetic insensitivity to induction of apoptosis. Surviving cells may contain sub- lethal levels of DNA damage and be induced to proliferate as an indirect result of the carcinogen-induced apoptotic cell death of surrounding tissue. This process would facilitate the acquisition mutations in the genome, possibly resulting in further insensitivity to apoptosis through activation of the bcl-2 oncogene or inactivation of the p53 tumor suppressor gene. In this context, the propensity of a cell to undergo apoptosis could be viewed as a selection pressure that a tumor cell must overcome. For neoplastic growth to occur, an imbalance between proliferation and apoptosis must be established such that cell growth predominates. Genetic mutations or epigenetic factors that diminish the propensity of a cell to undergo apoptosis may therefore confer on that cell a growth advantage.","Apoptosis: Inhibitor or instigator of carcinogenesis? Abs: Carcinogenesis is considered to require an initiating event that results in an irreversible genetic change in a subpopulation of cells. Based on the available evidence, it seems likely that apoptosis may act to attenuate this process by causing the deletion of genetically damaged cells from the host organism. Nevertheless, the existence of an active pathway leading to apoptotic cell death may be a double-edged sword, simply because it can be overcome. Some cells may exhibit preexisting genetic or epigenetic insensitivity to induction of apoptosis. Surviving cells may contain sub- lethal levels of DNA damage and be induced to proliferate as an indirect result of the carcinogen-induced apoptotic cell death of surrounding tissue. This process would facilitate the acquisition mutations in the genome, possibly resulting in further insensitivity to apoptosis through activation of the bcl-2 oncogene or inactivation of the p53 tumor suppressor gene. In this context, the propensity of a cell to undergo apoptosis could be viewed as a selection pressure that a tumor cell must overcome. For neoplastic growth to occur, an imbalance between proliferation and apoptosis must be established such that cell growth predominates. Genetic mutations or epigenetic factors that diminish the propensity of a cell to undergo apoptosis may therefore confer on that cell a growth advantage."
1576371,Laskin et al. 1970,Acute inhalation toxicity of calcium chromate,,Acute inhalation toxicity of calcium chromate Abs: 
1576364,NTP 2011,Chromium hexavalent compounds,,Chromium hexavalent compounds Abs: 
1576361,U.S. EPA 1992,Initial submission: Reports of asbestosis and lip cancer related to employee exposures to vermiculite and hexavalent chromium with cover dated 08/27/92,,Initial submission: Reports of asbestosis and lip cancer related to employee exposures to vermiculite and hexavalent chromium with cover dated 08/27/92 Abs: 
1576359,Radian Corp 1991,"Air toxic ""Hot Spots"" - AB 2588 health risk assessment Douglas Aircraft Company Torrance facility with attachments and cover letter dated 081291",,"Air toxic ""Hot Spots"" - AB 2588 health risk assessment Douglas Aircraft Company Torrance facility with attachments and cover letter dated 081291 Abs: "
1576358,U.S. EPA 1991,Health risk assessment in fulfillment of requirements under the AB2588 air toxics information and assessment act of 1987 with attachments and cover letter dated 081291,,Health risk assessment in fulfillment of requirements under the AB2588 air toxics information and assessment act of 1987 with attachments and cover letter dated 081291 Abs: 
1576354,Tabershaw Occupational Medicine Associates 1982,"Occupational health evaluation of the Newark, N.J. plant of Koppers Co., Inc.: Final report",,"Occupational health evaluation of the Newark, N.J. plant of Koppers Co., Inc.: Final report Abs: "
1576353,OTS 1982,"Occupational health evaluation of the Los Angeles, California plant of Koppers Company, INC",,"Occupational health evaluation of the Los Angeles, California plant of Koppers Company, INC Abs: "
1576352,U.S. EPA 1983,Toxicity screening using MicroTox with cover letter,,Toxicity screening using MicroTox with cover letter Abs: 
1576349,Reshetin et al. 2003,"Ambient hexavalent chromium concentrations and cancer mortality in Nihzi Novogorod, Russia","Goal, Scope and Background. This research estimates the impact of ambient concentrations of hexavalent chromium on the risk of excess lifetime cancer mortality in Nizhi Novogorod, Russia. Methods. Ambient air monitoring data for hexavalent chromium collected by the Rosgidromet (Russian Weather Service) in 1993 are used to assess the risk of cancer deaths attributable to exposure to that hazardous air pollutant. Results and Discussion. Using a unit risk factor of 1.2 x 10(-2) per mu g/m(3) indicates that aroximately 44 cancer-related deaths annually are estimated to be due to ambient exposure to hexavalent chromium. Conclusions. The results of this analysis underscore the importance of reducing exposure to hexavalent chromium to limit risk of cancer mortality.","Ambient hexavalent chromium concentrations and cancer mortality in Nihzi Novogorod, Russia Abs: Goal, Scope and Background. This research estimates the impact of ambient concentrations of hexavalent chromium on the risk of excess lifetime cancer mortality in Nizhi Novogorod, Russia. Methods. Ambient air monitoring data for hexavalent chromium collected by the Rosgidromet (Russian Weather Service) in 1993 are used to assess the risk of cancer deaths attributable to exposure to that hazardous air pollutant. Results and Discussion. Using a unit risk factor of 1.2 x 10(-2) per mu g/m(3) indicates that aroximately 44 cancer-related deaths annually are estimated to be due to ambient exposure to hexavalent chromium. Conclusions. The results of this analysis underscore the importance of reducing exposure to hexavalent chromium to limit risk of cancer mortality."
1576348,Industrial Health Foundation 2002,"Collaborative cohort mortality study of four chromate production facilities, 1958-1998",,"Collaborative cohort mortality study of four chromate production facilities, 1958-1998 Abs: "
1576347,Industrial Health Foundation 1987,Final report regarding testing sodium dichromate and soluble calcium chromate for carcinogenicity in rats with cover letter dated 042287,"Chronic toxicity and oncogenicity were evaluated in groups of male and female Sprague Dawley rats (40/sex/group) administered intratracheal doses of sodium dichromate for 30 months beginning at 10 weeks of age. Based on preliminary tests, animals were exposed to doses of 0.05, 0.25, or 1.25 mg/kg/week or 0.01, 0.05 or 0.25 mg/kg 5 times/week. Behavior, food intake, blood and urine tests, and mortality were not consistently affected by the treatment. Animals receiving 1.25 mg/kg/week had difficulty breathing for 30 minutes after treatment beginning on day 415. Reduced body weights were observed in 1.25 mg/kg/week males in comparison to controls. In high-dose animals, increased lung weights were reported. One benign lung tumor in 0.25 mg/kg/week animals and 12 benign and 8 malignant lung tumors in 1.25 mg/kg/week animals were observed. No lung tumors were found in the untreated controls or in the saline-controls. The investigators reported sodium dichromate had a weak carcinogenic effect after treatment at the highest weekly dose.","Final report regarding testing sodium dichromate and soluble calcium chromate for carcinogenicity in rats with cover letter dated 042287 Abs: Chronic toxicity and oncogenicity were evaluated in groups of male and female Sprague Dawley rats (40/sex/group) administered intratracheal doses of sodium dichromate for 30 months beginning at 10 weeks of age. Based on preliminary tests, animals were exposed to doses of 0.05, 0.25, or 1.25 mg/kg/week or 0.01, 0.05 or 0.25 mg/kg 5 times/week. Behavior, food intake, blood and urine tests, and mortality were not consistently affected by the treatment. Animals receiving 1.25 mg/kg/week had difficulty breathing for 30 minutes after treatment beginning on day 415. Reduced body weights were observed in 1.25 mg/kg/week males in comparison to controls. In high-dose animals, increased lung weights were reported. One benign lung tumor in 0.25 mg/kg/week animals and 12 benign and 8 malignant lung tumors in 1.25 mg/kg/week animals were observed. No lung tumors were found in the untreated controls or in the saline-controls. The investigators reported sodium dichromate had a weak carcinogenic effect after treatment at the highest weekly dose."
1576339,OTS 1987,FINAL REPORT REGARDING TESTING SODIUM DICHROMATE AND SOLUBLE CALCIUM CHROMATE FOR CARCINOGENICITY IN RATS WITH COVER LETTER DATED 042287,,FINAL REPORT REGARDING TESTING SODIUM DICHROMATE AND SOLUBLE CALCIUM CHROMATE FOR CARCINOGENICITY IN RATS WITH COVER LETTER DATED 042287 Abs: 
1576320,Kang et al. 2003,[Determination of chromium(III) and chromium(VI) in water using flow injection on-line preconcentration and separation with flame absorption spectrometric detection],"A rapid and sensitive method for the sequential determination of Cr(III) and Cr(VI) in water samples based on flow injection on-line preconcentration and separation with two-microcolumn system-flame atomic absorption spectrometry has been developed. The Cr(III) and Cr(VI) in water samples were respectively retained in a microcolum with cation exchange resin and in a microcolumn with anion exchange resin and were eluted directly by 15% HNO3 and 8% NH4NO3, respectively. The characteristic concentrations (pre-concentration time of 1 min) for Cr(III) and Cr(VI) were 1.50 micrograms.L-1 and 1.39 micrograms.L-1, respectively, The relative standard deviations at 10 micrograms.L-1 level were 3.41% and 1.80%, and the corresponding detection limits (3 sigma) were 1.03 micrograms.L-1 and 0.54 microgram.L-1, respectively. The satisfactory recovery of 93.48%-107.5% could be obtained from water samples.","[Determination of chromium(III) and chromium(VI) in water using flow injection on-line preconcentration and separation with flame absorption spectrometric detection] Abs: A rapid and sensitive method for the sequential determination of Cr(III) and Cr(VI) in water samples based on flow injection on-line preconcentration and separation with two-microcolumn system-flame atomic absorption spectrometry has been developed. The Cr(III) and Cr(VI) in water samples were respectively retained in a microcolum with cation exchange resin and in a microcolumn with anion exchange resin and were eluted directly by 15% HNO3 and 8% NH4NO3, respectively. The characteristic concentrations (pre-concentration time of 1 min) for Cr(III) and Cr(VI) were 1.50 micrograms.L-1 and 1.39 micrograms.L-1, respectively, The relative standard deviations at 10 micrograms.L-1 level were 3.41% and 1.80%, and the corresponding detection limits (3 sigma) were 1.03 micrograms.L-1 and 0.54 microgram.L-1, respectively. The satisfactory recovery of 93.48%-107.5% could be obtained from water samples."
1576319,Huang and  Chen 2002,"[Study on the oxidative coupling of p-amino-N,N-dimethylaniline with 1-amino-8-naphthol-3,6-disulfonic acid and its application]","A new catalytic spectrophotometic method for the determination of trace chromium (VI) is reported in this paper. The method is based on the catalytic action of chromium (VI) on the oxidative coupling of p-Amino-N,N-dimethylaniline dihydrochloride and 1-Amino-8-naphthol-3,6-disulfonic acid to form a colored dye (lambda max = 516 nm) in the presence of hydrogen peroxide. The mechanism of the reaction was discussed and its optimum conditions were established. The linear range of this method was 0.08-0.40 mg.L-1 and the relative standard deviation was found to be 1.1% for Cr(VI) (11 replicates). The detection limit for Cr(VI) is 2.0 x 10(-6) g.L-1. The method was used to determine Cr(VI) in waste water successfully.","[Study on the oxidative coupling of p-amino-N,N-dimethylaniline with 1-amino-8-naphthol-3,6-disulfonic acid and its application] Abs: A new catalytic spectrophotometic method for the determination of trace chromium (VI) is reported in this paper. The method is based on the catalytic action of chromium (VI) on the oxidative coupling of p-Amino-N,N-dimethylaniline dihydrochloride and 1-Amino-8-naphthol-3,6-disulfonic acid to form a colored dye (lambda max = 516 nm) in the presence of hydrogen peroxide. The mechanism of the reaction was discussed and its optimum conditions were established. The linear range of this method was 0.08-0.40 mg.L-1 and the relative standard deviation was found to be 1.1% for Cr(VI) (11 replicates). The detection limit for Cr(VI) is 2.0 x 10(-6) g.L-1. The method was used to determine Cr(VI) in waste water successfully."
1574558,Halioua et al. 2013,[Has application of the decree banning the use of cement with a high chromium VI content led to a reduction in occupational cement dermatitis in salaried workers in the construction industries?],"<strong>INTRODUCTION: </strong>Active employees in the construction industry are particularly exposed to occupational cement eczema (OCE) which affects the hands in 80 to 90% of cases. The importance of OCE in France and the impact of the application of decree n. 2005-577 on 26 May 2005 were estimated from data collected by the Occupational risks division of the French national health insurance fund for salaried workers (CNAMTS). This decree prohibits the placing on the market and use of cement (and preparations containing it) with a chromium VI content above 0.0002% in order to reduce its hazardousness.<br /><br /><strong>METHODS: </strong>All cases of OCE reported to and recognized by the CNAMTS between 1 January 2004 and 31 December 2008 among construction workers were selected. The following parameters were noted in each case: age, gender, industrial sector concerned, local French National health insurance agency, causal agent and the number of working days lost. The incidence per 100,000 salaried workers could be determined from the total number of salaried workers followed up by occupational medicine as well as those working in the construction industry.<br /><br /><strong>RESULTS: </strong>For the five years studied, 3698 cases of occupational eczema (OE) were reported in construction workers and this was 17.1% of the total number of cases of OE for all salaried employees (n=12.689). Cement was the causal agent most frequently involved in the construction sector (57.8%, 2139/3698). The annual incidence of OCE decreased from 37.8 to 21.1 new cases per 100,000 employees in the construction industry per year between 2004 and 2008. The total number of days lost from work due to OCE decreased by 39% during the study period.<br /><br /><strong>CONCLUSION: </strong>This descriptive study highlights the importance and socio-economic impact of OCE in the construction industry. Application of decree n. 2005-577 on 26 May 2005 may explain a reduction in OCE.","[Has application of the decree banning the use of cement with a high chromium VI content led to a reduction in occupational cement dermatitis in salaried workers in the construction industries?] Abs: <strong>INTRODUCTION: </strong>Active employees in the construction industry are particularly exposed to occupational cement eczema (OCE) which affects the hands in 80 to 90% of cases. The importance of OCE in France and the impact of the application of decree n. 2005-577 on 26 May 2005 were estimated from data collected by the Occupational risks division of the French national health insurance fund for salaried workers (CNAMTS). This decree prohibits the placing on the market and use of cement (and preparations containing it) with a chromium VI content above 0.0002% in order to reduce its hazardousness.<br /><br /><strong>METHODS: </strong>All cases of OCE reported to and recognized by the CNAMTS between 1 January 2004 and 31 December 2008 among construction workers were selected. The following parameters were noted in each case: age, gender, industrial sector concerned, local French National health insurance agency, causal agent and the number of working days lost. The incidence per 100,000 salaried workers could be determined from the total number of salaried workers followed up by occupational medicine as well as those working in the construction industry.<br /><br /><strong>RESULTS: </strong>For the five years studied, 3698 cases of occupational eczema (OE) were reported in construction workers and this was 17.1% of the total number of cases of OE for all salaried employees (n=12.689). Cement was the causal agent most frequently involved in the construction sector (57.8%, 2139/3698). The annual incidence of OCE decreased from 37.8 to 21.1 new cases per 100,000 employees in the construction industry per year between 2004 and 2008. The total number of days lost from work due to OCE decreased by 39% during the study period.<br /><br /><strong>CONCLUSION: </strong>This descriptive study highlights the importance and socio-economic impact of OCE in the construction industry. Application of decree n. 2005-577 on 26 May 2005 may explain a reduction in OCE."
1574526,Görlitzer and  Klanck 1999,"[Five-ring analogs of nifedipine. 3. Synthesis and reactions of 1,4-dihydropyridines with 4-(4-nitro-5-imidazolyl)-substituents]","In the Hantzsch pyridine synthesis the 4-nitro-5-imidazolylcarbaldehydes 4 react with methyl 3-aminocrotonate or 3-aminocrotononitrile in acetic acid to yield the 1,4-dihydropyridines (DHP) 5 and 6. The corresponding pyridines 7 and 8 are obtained by oxidation with cerium(IV) or chromium(VI), respectively. Reduction of the nitro group in 7 with iron in acetic acid leads to the lactames 9, while from 8a the imidazolylamine 10 is isolated. Compound 8a reacts with dithionite to yield the cyclic amidine 11. Irradiation of the DHP 5 and 6b with UV-A light affords the 4-nitroso-5-imidazolyl-pyridines 12 and 13. The half wave potentials E1/2 of the DHP 5 were determined by anodic oxidation using difference pulse voltammetry (DPV); nifedipine was used as reference substance. The DHP 5 inhibit the growth of Staphylococcus aureus in the platelet diffusion test.","[Five-ring analogs of nifedipine. 3. Synthesis and reactions of 1,4-dihydropyridines with 4-(4-nitro-5-imidazolyl)-substituents] Abs: In the Hantzsch pyridine synthesis the 4-nitro-5-imidazolylcarbaldehydes 4 react with methyl 3-aminocrotonate or 3-aminocrotononitrile in acetic acid to yield the 1,4-dihydropyridines (DHP) 5 and 6. The corresponding pyridines 7 and 8 are obtained by oxidation with cerium(IV) or chromium(VI), respectively. Reduction of the nitro group in 7 with iron in acetic acid leads to the lactames 9, while from 8a the imidazolylamine 10 is isolated. Compound 8a reacts with dithionite to yield the cyclic amidine 11. Irradiation of the DHP 5 and 6b with UV-A light affords the 4-nitroso-5-imidazolyl-pyridines 12 and 13. The half wave potentials E1/2 of the DHP 5 were determined by anodic oxidation using difference pulse voltammetry (DPV); nifedipine was used as reference substance. The DHP 5 inhibit the growth of Staphylococcus aureus in the platelet diffusion test."
1574522,García-Rodríguez et al. 2012,[Green tea and its role on chemoprevention in vivo of genotoxic damage induced by carcinogenic metals (chromium [VI])],"<strong>BACKGROUND: </strong>Consumption of green tea, by its antioxidant properties, has been associated with beneficial health effects, because antioxidant may play a role in the risk and pathogenesis of several chronic diseases, especially cardiovascular disease and cancer. On the other hand, it has been reported that metal compounds such as chromium [VI] are carcinogenic and can induce genotoxic damage through the Oxidative Stress. Therefore, it is possible that green tea has a protective effect against the genotoxic damage induced by this compounds.<br /><br /><strong>OBJECTIVE: </strong>To evaluate the effect of oral administration of green tea over the genotoxic damage induced by Cr [VI] by quantification of micronucleus (MN) in polychromatic erythrocytes (EPC).<br /><br /><strong>MATERIALS AND METHODS: </strong>We use mice of CD-1 strain that were randomly divided into the following groups: (i) control, (ii) treatment with green tea, (iii) treatment with chromium trioxide, (iv) treatment with green tea and chromium trioxide. The green tea was administrated via intragastric tube every 12 hours over two days (4 doses of 0.25 ml infusions 1.6 g/7.5 ml) and ad libitum (5.6 ml/day for 10 days infusions of 3.2 g/100 ml), while chromium trioxide was administrated via intraperitoneal (20 mg/kg). Blood samples were obtained from the caudal vein, the number of MN in EPC was assessed at 0, 24, 48 and 72 hours after the treatments.<br /><br /><strong>RESULTS: </strong>The group treated with green tea showed no significant statistical changes in the average of MN. On the other hand, the group that was dosed with the chromium trioxide showed an increase between 4 and 8 MN, which was statistically significant when compared with control group, which confirmed the genotoxic damage. When the green tea treatment was administered before the application of chromium trioxide, there was a decrease in MN frequencies of 31 and 62% at 72 hours, 20 and 35% at 48 hours and 18 and 31% at 24 hours with intragastric and ad libitum respectively, compared with the group treated only with chromium trioxide. Hence, green tea reduced the genotoxic damage induced by chromium trioxide, and the highest protection was presented at 72 hours.<br /><br /><strong>CONCLUSIONS: </strong>Our findings support the protective effects of green tea against the damage of genetic material, induced by metal compounds such as chromium [VI], suggesting that its antioxidant compounds are those that have a chemopreventive effect on the EOX generated by the Cr [VI] during its reduction to Cr (III). The fact that the largest decrease in the frequency of MN was observed at 72 hours and ad libitum treatment, suggests that, the protective effect depends on the bioavailability, pharmacodynamics and pharmacokinetics of the active ingredient in green tea, so the administration of green tea for a long period of time before the exposure to Cr [VI] could have a more consistent preventive effect.","[Green tea and its role on chemoprevention in vivo of genotoxic damage induced by carcinogenic metals (chromium [VI])] Abs: <strong>BACKGROUND: </strong>Consumption of green tea, by its antioxidant properties, has been associated with beneficial health effects, because antioxidant may play a role in the risk and pathogenesis of several chronic diseases, especially cardiovascular disease and cancer. On the other hand, it has been reported that metal compounds such as chromium [VI] are carcinogenic and can induce genotoxic damage through the Oxidative Stress. Therefore, it is possible that green tea has a protective effect against the genotoxic damage induced by this compounds.<br /><br /><strong>OBJECTIVE: </strong>To evaluate the effect of oral administration of green tea over the genotoxic damage induced by Cr [VI] by quantification of micronucleus (MN) in polychromatic erythrocytes (EPC).<br /><br /><strong>MATERIALS AND METHODS: </strong>We use mice of CD-1 strain that were randomly divided into the following groups: (i) control, (ii) treatment with green tea, (iii) treatment with chromium trioxide, (iv) treatment with green tea and chromium trioxide. The green tea was administrated via intragastric tube every 12 hours over two days (4 doses of 0.25 ml infusions 1.6 g/7.5 ml) and ad libitum (5.6 ml/day for 10 days infusions of 3.2 g/100 ml), while chromium trioxide was administrated via intraperitoneal (20 mg/kg). Blood samples were obtained from the caudal vein, the number of MN in EPC was assessed at 0, 24, 48 and 72 hours after the treatments.<br /><br /><strong>RESULTS: </strong>The group treated with green tea showed no significant statistical changes in the average of MN. On the other hand, the group that was dosed with the chromium trioxide showed an increase between 4 and 8 MN, which was statistically significant when compared with control group, which confirmed the genotoxic damage. When the green tea treatment was administered before the application of chromium trioxide, there was a decrease in MN frequencies of 31 and 62% at 72 hours, 20 and 35% at 48 hours and 18 and 31% at 24 hours with intragastric and ad libitum respectively, compared with the group treated only with chromium trioxide. Hence, green tea reduced the genotoxic damage induced by chromium trioxide, and the highest protection was presented at 72 hours.<br /><br /><strong>CONCLUSIONS: </strong>Our findings support the protective effects of green tea against the damage of genetic material, induced by metal compounds such as chromium [VI], suggesting that its antioxidant compounds are those that have a chemopreventive effect on the EOX generated by the Cr [VI] during its reduction to Cr (III). The fact that the largest decrease in the frequency of MN was observed at 72 hours and ad libitum treatment, suggests that, the protective effect depends on the bioavailability, pharmacodynamics and pharmacokinetics of the active ingredient in green tea, so the administration of green tea for a long period of time before the exposure to Cr [VI] could have a more consistent preventive effect."
1574517,Fu et al. 2012,[Remediation of chromium (VI) contaminated soils using permeable reactive composite electrodes technology],"Electrokinetic transport processes have been shown to have potential for the effective removal of heavy metals from soils. However, pH changes near the anode and cathode limit their widespread application in the remediation of contaminated soils. Permeable reactive composite electrodes (PRCE) were made by attaching reactive materials such as Fe(0) and zeolite to the electrodes, and the effects of the composite electrodes on pH control, chromium removal efficiency and Cr speciation changes were studied in the electrokinetic remediation process of Cr( VI) contaminated soil. Composite electrodes consisting of permeable reactive materials gave better pH control and Cr removal efficiency compared to traditional electrodes, and a Fe(0) + zeolite reactive layer in the anode exhibited the best performance compared to zeolite or Fe(0) alone. After 5 days of electrokinetic remediation with a DC voltage of 2 V x cm(-1), the Fe(0) + zeolite reactive layer lowered the pH fluctuation, maintained the soil pH in the range of 5.5 to 8.5, raised the Cr(VI) removal efficiency up to 97% in any soil section, produced lower Cr(III) residues, enhanced the amount of Cr retention up to 8 and 1.8 times respectively, and transformed 98% of the Cr(VI) into lower toxicity Cr(III). This study provides a theoretical basis for the exploitation of permeable reactive composite electrodes which are a practical option for future applications.","[Remediation of chromium (VI) contaminated soils using permeable reactive composite electrodes technology] Abs: Electrokinetic transport processes have been shown to have potential for the effective removal of heavy metals from soils. However, pH changes near the anode and cathode limit their widespread application in the remediation of contaminated soils. Permeable reactive composite electrodes (PRCE) were made by attaching reactive materials such as Fe(0) and zeolite to the electrodes, and the effects of the composite electrodes on pH control, chromium removal efficiency and Cr speciation changes were studied in the electrokinetic remediation process of Cr( VI) contaminated soil. Composite electrodes consisting of permeable reactive materials gave better pH control and Cr removal efficiency compared to traditional electrodes, and a Fe(0) + zeolite reactive layer in the anode exhibited the best performance compared to zeolite or Fe(0) alone. After 5 days of electrokinetic remediation with a DC voltage of 2 V x cm(-1), the Fe(0) + zeolite reactive layer lowered the pH fluctuation, maintained the soil pH in the range of 5.5 to 8.5, raised the Cr(VI) removal efficiency up to 97% in any soil section, produced lower Cr(III) residues, enhanced the amount of Cr retention up to 8 and 1.8 times respectively, and transformed 98% of the Cr(VI) into lower toxicity Cr(III). This study provides a theoretical basis for the exploitation of permeable reactive composite electrodes which are a practical option for future applications."
1574412,Ermolina et al. 2012,[Morphological features of the organs of the immune system in conditions of exposure to chromium and benzene],"Morphological features of the thymus, spleen and lymph nodes on the 45th--and 90th day of oral exposure to benzene, potassium dichromate and their mixtures were studied in 40 Wistar rats. A strong trend to a decrease in the activity of T lymphocytes has been established. Apoptotic thymocytes and lymphocytes in the T-dependent areas of spleen and lymph nodes have been revealed.","[Morphological features of the organs of the immune system in conditions of exposure to chromium and benzene] Abs: Morphological features of the thymus, spleen and lymph nodes on the 45th--and 90th day of oral exposure to benzene, potassium dichromate and their mixtures were studied in 40 Wistar rats. A strong trend to a decrease in the activity of T lymphocytes has been established. Apoptotic thymocytes and lymphocytes in the T-dependent areas of spleen and lymph nodes have been revealed."
1574411,Ding et al. 2012,[Mechanism of Cr( VI) removal from aqueous solution using biochar promoted by humic acid],"Biochar derived from excess sludge was used for hexavalent chromium [Cr( VI)] removal from water as a sorbent, and impacts of co-existing humic acid on performance of Cr( VI) sorption onto biochar were studied. The experimental results indicated that humic acid facilitated biochar adsorption of Cr(VI), which enhanced capacity of Cr sorption and shortened reaction time reaching equilibrium remarkably. The sorption kinetic process could be described with the pseudo second order model. On the condition of initial pH 4.0, biochar concentration 20 g x L(-1), initial concentration of Cr(VI) in the range of 50-800 mg x L(-1), the Langmuir model fitted adsorption isotherm better than the Freudlich model. The Langmuir Q0 values of biochar with and without existing humic acid were 10.10 mg x g(-1) and 5.56 mg x g(-1), respectively. In the pH range of 2.0-8.0, sorption capacity of all sorbents decreased with increasing initial pH value. Ascending concentration of humic acid in solution promoted sorption capacity of biochar. Fourier transform infrared spectroscopy (FTIR) analysis showed that hydroxyl, carboxyl, ester, aromatic C-H stretch and ring C=C on the biochar were responsible for Cr(VI) sorption. Combined with X-ray photoelectron spectroscopy (XPS) analysis, mechanism of promoting Cr( VI) sorption onto biochar was speculated that humic acid enhanced concentration of Cr( VI) ions aggregating on the surface of biochar and benefited Cr(VI) adsorption coupled with subsequent reduction by biochar functional groups. Meanwhile, humic acid also increased amount of Cr(VI) and Cr(II) removal from aqueous solution.","[Mechanism of Cr( VI) removal from aqueous solution using biochar promoted by humic acid] Abs: Biochar derived from excess sludge was used for hexavalent chromium [Cr( VI)] removal from water as a sorbent, and impacts of co-existing humic acid on performance of Cr( VI) sorption onto biochar were studied. The experimental results indicated that humic acid facilitated biochar adsorption of Cr(VI), which enhanced capacity of Cr sorption and shortened reaction time reaching equilibrium remarkably. The sorption kinetic process could be described with the pseudo second order model. On the condition of initial pH 4.0, biochar concentration 20 g x L(-1), initial concentration of Cr(VI) in the range of 50-800 mg x L(-1), the Langmuir model fitted adsorption isotherm better than the Freudlich model. The Langmuir Q0 values of biochar with and without existing humic acid were 10.10 mg x g(-1) and 5.56 mg x g(-1), respectively. In the pH range of 2.0-8.0, sorption capacity of all sorbents decreased with increasing initial pH value. Ascending concentration of humic acid in solution promoted sorption capacity of biochar. Fourier transform infrared spectroscopy (FTIR) analysis showed that hydroxyl, carboxyl, ester, aromatic C-H stretch and ring C=C on the biochar were responsible for Cr(VI) sorption. Combined with X-ray photoelectron spectroscopy (XPS) analysis, mechanism of promoting Cr( VI) sorption onto biochar was speculated that humic acid enhanced concentration of Cr( VI) ions aggregating on the surface of biochar and benefited Cr(VI) adsorption coupled with subsequent reduction by biochar functional groups. Meanwhile, humic acid also increased amount of Cr(VI) and Cr(II) removal from aqueous solution."
1574409,Cherevatyi 1963,[Effect of hexavalent chromium on the microorganism],,[Effect of hexavalent chromium on the microorganism] Abs: 
1574408,Chen et al. 2010,[Antagonistic effect of N-acetylcysteine on apoptosis of L-02 hepatocyte induced by Cr(VI) with or without caspase inhibitor],"<strong>OBJECTIVE: </strong>To explore the antagonistic effect of N-acetylcysteine (NAC) on hexevalent chromium (Cr(VI))-induced apoptosis in L-02 hepatocytes with or without caspase inhibitors.<br /><br /><strong>METHODS: </strong>L-02 hepatocytes were randomly divided into a control group, and Cr( VI), Z-VAD-fmk + Cr(VI), NAC + Cr(VI), Z-VAD-fmk + NAC + Cr (VI) four treatment groups, in which L-02 hepatocytes were cultured with Cr (VI) at the dose of 20 micromol/L for 6h. The rates of apoptosis in all groups were detected by flow cytometry (FC) after staining with propidium iodide (PI). The changes of mitochondrial membrane potential (deltapsim) and permeability transition pore (PTP) were determined by fluorescent spectrometer. The DNA damages in hepatocytes were observed by the single cell gel electrophoresis (SCGE).<br /><br /><strong>RESULTS: </strong>Cr(VI) significantly induced apoptosis of L-02 hepatocytes at the dose of 20 micromol/L for 6 hours (P &lt; 0.05). However, NAC significantly decreased the rates of apoptosis of L-02 hepatocytes and alleviated the damages to mitochondria and DNA caused by Cr(VI) in L-02 hepatocytes with or without caspase (P &lt; 0.05). However, in comparition with the non caspase-inhibited group, the protective effects of NAC decreased in the caspase-inhibited group (P &lt; 0.05).<br /><br /><strong>CONCLUSION: </strong>NAC could protect the apoptosis of L-02 hepatocyte induced with Cr(VI) with or without caspase inhibitor, and caspase could not play a decisive role in this process.","[Antagonistic effect of N-acetylcysteine on apoptosis of L-02 hepatocyte induced by Cr(VI) with or without caspase inhibitor] Abs: <strong>OBJECTIVE: </strong>To explore the antagonistic effect of N-acetylcysteine (NAC) on hexevalent chromium (Cr(VI))-induced apoptosis in L-02 hepatocytes with or without caspase inhibitors.<br /><br /><strong>METHODS: </strong>L-02 hepatocytes were randomly divided into a control group, and Cr( VI), Z-VAD-fmk + Cr(VI), NAC + Cr(VI), Z-VAD-fmk + NAC + Cr (VI) four treatment groups, in which L-02 hepatocytes were cultured with Cr (VI) at the dose of 20 micromol/L for 6h. The rates of apoptosis in all groups were detected by flow cytometry (FC) after staining with propidium iodide (PI). The changes of mitochondrial membrane potential (deltapsim) and permeability transition pore (PTP) were determined by fluorescent spectrometer. The DNA damages in hepatocytes were observed by the single cell gel electrophoresis (SCGE).<br /><br /><strong>RESULTS: </strong>Cr(VI) significantly induced apoptosis of L-02 hepatocytes at the dose of 20 micromol/L for 6 hours (P &lt; 0.05). However, NAC significantly decreased the rates of apoptosis of L-02 hepatocytes and alleviated the damages to mitochondria and DNA caused by Cr(VI) in L-02 hepatocytes with or without caspase (P &lt; 0.05). However, in comparition with the non caspase-inhibited group, the protective effects of NAC decreased in the caspase-inhibited group (P &lt; 0.05).<br /><br /><strong>CONCLUSION: </strong>NAC could protect the apoptosis of L-02 hepatocyte induced with Cr(VI) with or without caspase inhibitor, and caspase could not play a decisive role in this process."
1574075,Cao et al. 2012,[Biosorption of chromium (VI) by waste biomass of epsilon-poly-L-lysine fermentation],"The sorption of hexavalent chromium by waste biomass of epsilon-Poly-L-lysine fermentation strains (Streptomyces albulus) PD-1 was studied. Effects of pretreatment ways, pH, initial concentration of Cr(VI), contact time and temperature on biosorption were determined. It was found that homogenization in HCl was the best way to pretreat mycelia, having an increased rate of Cr(VI) biosorption at 22.7%, the optimum pH was about 2.0, while no significant impact of temperature on the biosorption was observed. The fitness of the experimental data for the Langmuir and Freundlich adsorption models was further examined and good correlations with R2 of 0.979 4 and 0.979 8 were observed, indicating the presence of both monolayer biosorption and heterogeneous surface condition. The maximum adsorption capacity of the Streptomyces albulus PD-1 for Cr(VI) was 23.92 mg x g(-1). FT-IR analysis demonstrates that the major functional groups (amide and hydroxyl) may contribute to the absorption of Cr(VI).","[Biosorption of chromium (VI) by waste biomass of epsilon-poly-L-lysine fermentation] Abs: The sorption of hexavalent chromium by waste biomass of epsilon-Poly-L-lysine fermentation strains (Streptomyces albulus) PD-1 was studied. Effects of pretreatment ways, pH, initial concentration of Cr(VI), contact time and temperature on biosorption were determined. It was found that homogenization in HCl was the best way to pretreat mycelia, having an increased rate of Cr(VI) biosorption at 22.7%, the optimum pH was about 2.0, while no significant impact of temperature on the biosorption was observed. The fitness of the experimental data for the Langmuir and Freundlich adsorption models was further examined and good correlations with R2 of 0.979 4 and 0.979 8 were observed, indicating the presence of both monolayer biosorption and heterogeneous surface condition. The maximum adsorption capacity of the Streptomyces albulus PD-1 for Cr(VI) was 23.92 mg x g(-1). FT-IR analysis demonstrates that the major functional groups (amide and hydroxyl) may contribute to the absorption of Cr(VI)."
1574074,Burenko et al. 1989,[Detection of trivalent chromium in the air],"The study was designed to develop an accelerated technique of air identification of trivalent chromium. The technique for alkali melting at 800-850 degrees, traditionally used for sample preparation, was replaced by acid treatment by a mixture of nitric, hydrochloric and chloric acids. Thus trivalent chromium was oxidized into hexavalent one, which was determined by means of the photocolorimetric technique by its reaction with diphenylcarbazite. The technique enabled one to lower the time for the analysis by 4 hours.","[Detection of trivalent chromium in the air] Abs: The study was designed to develop an accelerated technique of air identification of trivalent chromium. The technique for alkali melting at 800-850 degrees, traditionally used for sample preparation, was replaced by acid treatment by a mixture of nitric, hydrochloric and chloric acids. Thus trivalent chromium was oxidized into hexavalent one, which was determined by means of the photocolorimetric technique by its reaction with diphenylcarbazite. The technique enabled one to lower the time for the analysis by 4 hours."
1573997,Balbi et al. 1981,[Specific effects of Cr ions on DNA: a comparison between the interaction of CrIII with purified DNA and with DNA from cultured cells],Affinity between CrIII and purified calf thymus DNA were studied by equilibrium dialysis at different pHs. Chromium was dosed by atomic spectrometry. This affinity was compared with Chromium-DNA affinity after treatment of living mammalian cells with CrVI and its intracellular reduction. Preliminary results seem to suggest that affinity is similar in both cases and not especially high (K approximately 10(5) 1/mole).,[Specific effects of Cr ions on DNA: a comparison between the interaction of CrIII with purified DNA and with DNA from cultured cells] Abs: Affinity between CrIII and purified calf thymus DNA were studied by equilibrium dialysis at different pHs. Chromium was dosed by atomic spectrometry. This affinity was compared with Chromium-DNA affinity after treatment of living mammalian cells with CrVI and its intracellular reduction. Preliminary results seem to suggest that affinity is similar in both cases and not especially high (K approximately 10(5) 1/mole).
1573995,Babiak et al. 2005,[Selection and properties of mutant yeast Pichia guilliermondii strains resistant to chromium (VI)],"Yeast Pichia guilliermondii strains L3 and L2, exposed to UV mutagenesis, produced over 80 mutants capable of growing on media containing 1.5 mM bichromate (Cr(VI)). The mutations making the strains resistant to Cr(VI) were dominant or semidominant. The mutants varied in Cr(VI) resistance, the degree of chromium accumulation in the cells (from 0.1 to 11.6 mg/g dry cells), and the degree of Cr(VI) reduction (from 50% to complete disappearance of bichromate from the culture liquid). Chromium accumulation in mutant cells depended on medium composition, Cr(VI) concentration, and the time of exposure to Cr(VI). The resistance to bichromate can be caused by various reasons: decrease in chromium absorption, altered ability to reduce Nr(VI), or damage of sulfate transport mechanisms.","[Selection and properties of mutant yeast Pichia guilliermondii strains resistant to chromium (VI)] Abs: Yeast Pichia guilliermondii strains L3 and L2, exposed to UV mutagenesis, produced over 80 mutants capable of growing on media containing 1.5 mM bichromate (Cr(VI)). The mutations making the strains resistant to Cr(VI) were dominant or semidominant. The mutants varied in Cr(VI) resistance, the degree of chromium accumulation in the cells (from 0.1 to 11.6 mg/g dry cells), and the degree of Cr(VI) reduction (from 50% to complete disappearance of bichromate from the culture liquid). Chromium accumulation in mutant cells depended on medium composition, Cr(VI) concentration, and the time of exposure to Cr(VI). The resistance to bichromate can be caused by various reasons: decrease in chromium absorption, altered ability to reduce Nr(VI), or damage of sulfate transport mechanisms."
1573397,Xia et al. 2013,Simultaneous removal of selected oxidized contaminants in groundwater using a continuously stirred hydrogen-based membrane biofilm reactor,"A laboratory trial was conducted for evaluating the capability of a continuously stirred hydrogen-based membrane biofilm reactor to simultaneously reduce nitrate (NO(3-)-N), sulfate (SO4(2-)), bromate (BrO3-), hexavalent chromium (Cr(VI)) and parachloronitrobenzene (p-CNB). The reactor contained two bundles of hollow fiber membranes functioning as an autotrophic biofilm carrier and hydrogen pipe as well. On the condition that hydrogen was supplied as electron donor and diffused into water through membrane pores, autohydrogenotrophic bacteria were capable of reducing contaminants to forms with lower toxicity. Reduction occurred within 1 day and removal fluxes for NO(3-)-N, SO4(2-), BrO3-, Cr(VI), and p-CNB reached 0.641, 2.396, 0.008, 0.016 and 0.031 g/(day x m2), respectively after 112 days of continuous operation. Except for the fact that sulfate was 37% removed under high surface loading, the other four contaminants were reduced by over 95%. The removal flux comparison between phases varying in surface loading and H2 pressure showed that decreasing surface loading or increasing H2 pressure would promote removal flux. Competition for electrons occurred among the five contaminants. Electron-equivalent flux analysis showed that the amount of utilized hydrogen was mainly controlled by NO(3-)-N and SO4(2-) reduction, which accounted for over 99% of the electron flux altogether. It also indicated the electron acceptor order, showing that nitrate was the most prior electron acceptor while suIfate was the second of the five contaminants.","Simultaneous removal of selected oxidized contaminants in groundwater using a continuously stirred hydrogen-based membrane biofilm reactor Abs: A laboratory trial was conducted for evaluating the capability of a continuously stirred hydrogen-based membrane biofilm reactor to simultaneously reduce nitrate (NO(3-)-N), sulfate (SO4(2-)), bromate (BrO3-), hexavalent chromium (Cr(VI)) and parachloronitrobenzene (p-CNB). The reactor contained two bundles of hollow fiber membranes functioning as an autotrophic biofilm carrier and hydrogen pipe as well. On the condition that hydrogen was supplied as electron donor and diffused into water through membrane pores, autohydrogenotrophic bacteria were capable of reducing contaminants to forms with lower toxicity. Reduction occurred within 1 day and removal fluxes for NO(3-)-N, SO4(2-), BrO3-, Cr(VI), and p-CNB reached 0.641, 2.396, 0.008, 0.016 and 0.031 g/(day x m2), respectively after 112 days of continuous operation. Except for the fact that sulfate was 37% removed under high surface loading, the other four contaminants were reduced by over 95%. The removal flux comparison between phases varying in surface loading and H2 pressure showed that decreasing surface loading or increasing H2 pressure would promote removal flux. Competition for electrons occurred among the five contaminants. Electron-equivalent flux analysis showed that the amount of utilized hydrogen was mainly controlled by NO(3-)-N and SO4(2-) reduction, which accounted for over 99% of the electron flux altogether. It also indicated the electron acceptor order, showing that nitrate was the most prior electron acceptor while suIfate was the second of the five contaminants."
1572820,Whittleston et al. 2013,"Enhancing microbial iron reduction in hyperalkaline, chromium contaminated sediments by pH amendment",,"Enhancing microbial iron reduction in hyperalkaline, chromium contaminated sediments by pH amendment Abs: "
1535744,Dedkova et al. 2013,"Sorption-spectrophotometric determination of zirconium and chromium(VI) from a single sample on a two-layer support using Arsenazo III and 1,5-diphenylcarbazide",,"Sorption-spectrophotometric determination of zirconium and chromium(VI) from a single sample on a two-layer support using Arsenazo III and 1,5-diphenylcarbazide Abs: "
1526768,Bhuvaneshwari et al. 2011,Biosorption of Chromium from Aqueous Waste Water using Chitosan and Desorption of Chromium from Biosorbent for Effective Reuse,,Biosorption of Chromium from Aqueous Waste Water using Chitosan and Desorption of Chromium from Biosorbent for Effective Reuse Abs: 
1526311,Berraksu et al. 2013,Use of Forestry Wastes for Biosorption of Dyes and Cr (VI),,Use of Forestry Wastes for Biosorption of Dyes and Cr (VI) Abs: 
1522379,Wang et al. 2013,Polyacrylonitrile/polypyrrole core/shell nanofiber mat for the removal of hexavalent chromium from aqueous solution,"Polyacrylonitrile/polypyrrole (PAN/PPy) core-shell structure nanofibers were prepared via electrospinning followed by in situ polymerization of pyrrole monomer for the removal of hexavalent chromium (Cr(VI)) from aqueous solution. Attenuated total reflections Fourier transform infrared (ATR-FTIR) and X-ray photoelectron spectroscopy (XPS) results confirmed the presence of the polypyrrole (PPy) layer on the surface of PAN nanofibers. The morphology and structure of the core-shell PAN/PPy nanofibers were studied by scanning electron microscopy (SEM) and transmission electron microscope (TEM), and the core-shell structure can be clearly proved from the SEM and TEM images. Adsorption results indicated that the adsorption capacity increased with the initial solution pH decreased. The adsorption equilibrium reached within 30 and 90 min as the initial solution concentration increased from 100 to 200mg/L, and the process can be described using the pseudo-second-order model. Isotherm data fitted well to the Langmuir isotherm model. Thermodynamic study revealed that the adsorption process is endothermic and spontaneous in nature. Desorption results showed that the adsorption capacity can remain up to 80% after 5 times usage. The adsorption mechanism was also studied by XPS.","Polyacrylonitrile/polypyrrole core/shell nanofiber mat for the removal of hexavalent chromium from aqueous solution Abs: Polyacrylonitrile/polypyrrole (PAN/PPy) core-shell structure nanofibers were prepared via electrospinning followed by in situ polymerization of pyrrole monomer for the removal of hexavalent chromium (Cr(VI)) from aqueous solution. Attenuated total reflections Fourier transform infrared (ATR-FTIR) and X-ray photoelectron spectroscopy (XPS) results confirmed the presence of the polypyrrole (PPy) layer on the surface of PAN nanofibers. The morphology and structure of the core-shell PAN/PPy nanofibers were studied by scanning electron microscopy (SEM) and transmission electron microscope (TEM), and the core-shell structure can be clearly proved from the SEM and TEM images. Adsorption results indicated that the adsorption capacity increased with the initial solution pH decreased. The adsorption equilibrium reached within 30 and 90 min as the initial solution concentration increased from 100 to 200mg/L, and the process can be described using the pseudo-second-order model. Isotherm data fitted well to the Langmuir isotherm model. Thermodynamic study revealed that the adsorption process is endothermic and spontaneous in nature. Desorption results showed that the adsorption capacity can remain up to 80% after 5 times usage. The adsorption mechanism was also studied by XPS."
1519059,Lozano and  Dussán ,Metal tolerance and larvicidal activity of Lysinibacillus sphaericus,"Lysinibacillus sphaericus is a spore-forming bacterium used in the biological control of mosquitoes and in bioremediation. Mosquito larvae exposed to heavy metals are tolerant to concentrations above the permissible limit for industrial residual waters. In this work, we characterize 51 L. sphaericus strains for metal tolerance and larvicidal activity against Culex quinquefasciatus. Lysinibacillus sphaericus OT4b.2, OT4b.20, OT4b.25, OT4b.26 and OT4b.58 were as toxic as the spores of the reference strain 2362 against C. quinquefasciatus larvae. 19 Mosquito-pathogenic L. sphaericus strains and 6 non-pathogenic strains were able to grow in arsenate, hexavalent chromium and/or lead. 16S rRNA gene sequences and phylogenetic analyses clustered 84 % of the metal-tolerant strains in L. sphaericus group 1, which encompasses the mosquitocidal strains. The larvicidal activity of vegetative and sporulated cells and its high tolerance to arsenate, hexavalent chromium and lead indicate that L. sphaericus OT4b.26 is a strong candidate for further studies examining its potential for biological control of mosquitoes in waters contaminated with metals.","Metal tolerance and larvicidal activity of Lysinibacillus sphaericus Abs: Lysinibacillus sphaericus is a spore-forming bacterium used in the biological control of mosquitoes and in bioremediation. Mosquito larvae exposed to heavy metals are tolerant to concentrations above the permissible limit for industrial residual waters. In this work, we characterize 51 L. sphaericus strains for metal tolerance and larvicidal activity against Culex quinquefasciatus. Lysinibacillus sphaericus OT4b.2, OT4b.20, OT4b.25, OT4b.26 and OT4b.58 were as toxic as the spores of the reference strain 2362 against C. quinquefasciatus larvae. 19 Mosquito-pathogenic L. sphaericus strains and 6 non-pathogenic strains were able to grow in arsenate, hexavalent chromium and/or lead. 16S rRNA gene sequences and phylogenetic analyses clustered 84 % of the metal-tolerant strains in L. sphaericus group 1, which encompasses the mosquitocidal strains. The larvicidal activity of vegetative and sporulated cells and its high tolerance to arsenate, hexavalent chromium and lead indicate that L. sphaericus OT4b.26 is a strong candidate for further studies examining its potential for biological control of mosquitoes in waters contaminated with metals."
1518980,Beaumont et al. 2008,Cancer mortality in a Chinese population exposed to hexavalent chromium in drinking water,"<strong>BACKGROUND: </strong>In 1987, investigators in Liaoning Province, China, reported that mortality rates for all cancer, stomach cancer, and lung cancer in 1970-1978 were higher in villages with hexavalent chromium (Cr+6)-contaminated drinking water than in the general population. The investigators reported rates, but did not report statistical measures of association or precision.<br /><br /><strong>METHODS: </strong>Using reports and other communications from investigators at the local Jinzhou Health and Anti-Epidemic Station, we obtained data on Cr+6 contamination of groundwater and cancer mortality in 9 study regions near a ferrochromium factory. We estimated: (1) person-years at risk in the study regions, based on census and population growth rate data, (2) mortality counts, based on estimated person-years at risk and previously reported mortality rates, and (3) rate ratios and 95% confidence intervals.<br /><br /><strong>RESULTS: </strong>The all-cancer mortality rate in the combined 5 study regions with Cr+6-contaminated water was negligibly elevated in comparison with the rate in the 4 combined study regions without contaminated water (rate ratio = 1.13; 95% confidence interval = 0.86-1.46), but was somewhat more elevated in comparison with the whole province (1.23; 0.97-1.53). Stomach cancer mortality in the regions with contaminated water was more substantially elevated in comparison with the regions without contaminated water (1.82; 1.11-2.91) and the whole province (1.69; 1.12-2.44). Lung cancer mortality was slightly elevated in comparison with the unexposed study regions (1.15; 0.62-2.07), and more strongly elevated in comparison with the whole province (1.78; 1.03-2.87). Mortality from other cancers combined was not elevated in comparison with either the unexposed study regions (0.86; 0.53-1.36) or the whole province (0.92; 0.58-1.38).<br /><br /><strong>CONCLUSIONS: </strong>While these data are limited, they are consistent with increased stomach cancer risk in a population exposed to Crz=6 in drinking water.","Cancer mortality in a Chinese population exposed to hexavalent chromium in drinking water Abs: <strong>BACKGROUND: </strong>In 1987, investigators in Liaoning Province, China, reported that mortality rates for all cancer, stomach cancer, and lung cancer in 1970-1978 were higher in villages with hexavalent chromium (Cr+6)-contaminated drinking water than in the general population. The investigators reported rates, but did not report statistical measures of association or precision.<br /><br /><strong>METHODS: </strong>Using reports and other communications from investigators at the local Jinzhou Health and Anti-Epidemic Station, we obtained data on Cr+6 contamination of groundwater and cancer mortality in 9 study regions near a ferrochromium factory. We estimated: (1) person-years at risk in the study regions, based on census and population growth rate data, (2) mortality counts, based on estimated person-years at risk and previously reported mortality rates, and (3) rate ratios and 95% confidence intervals.<br /><br /><strong>RESULTS: </strong>The all-cancer mortality rate in the combined 5 study regions with Cr+6-contaminated water was negligibly elevated in comparison with the rate in the 4 combined study regions without contaminated water (rate ratio = 1.13; 95% confidence interval = 0.86-1.46), but was somewhat more elevated in comparison with the whole province (1.23; 0.97-1.53). Stomach cancer mortality in the regions with contaminated water was more substantially elevated in comparison with the regions without contaminated water (1.82; 1.11-2.91) and the whole province (1.69; 1.12-2.44). Lung cancer mortality was slightly elevated in comparison with the unexposed study regions (1.15; 0.62-2.07), and more strongly elevated in comparison with the whole province (1.78; 1.03-2.87). Mortality from other cancers combined was not elevated in comparison with either the unexposed study regions (0.86; 0.53-1.36) or the whole province (0.92; 0.58-1.38).<br /><br /><strong>CONCLUSIONS: </strong>While these data are limited, they are consistent with increased stomach cancer risk in a population exposed to Crz=6 in drinking water."
1516688,Pechova and  Pavlata 2007,Chromium as an essential nutrient: a review,"Chromium (Cr) has been studied since the end of the 19(th) century, when carcinogenic effects of hexavalent Cr were discovered. Essentiality of trivalent Cr was demonstrated in 1959; Cr3+ has been studied in humans and laboratory animals since the 1970s and it is only since the 1990s that Cr has been studied as an essential element in livestock animals with the same intensity. Trivalent chromium is essential to normal carbohydrate, lipid and protein metabolism. Chromium is biologically active as part of an oligopeptide - chromodulin - potentiating the effect of insulin by facilitating insulin binding to receptors at the cell surface. With chromium acting as a cofactor of insulin, Cr activity in the organism is parallel to insulin functions. Cr absorption is low, ranging between 0.4 and 2.0% for inorganic compounds while the availability of organic Cr is more than 10 times higher. Absorbed Cr circulates in blood bound to the beta-globulin plasma fraction and is transported to tissues bound to transferrin. Absorbed Cr is excreted primarily in urine, by glomerular filtration; a small amount is excreted through perspiration, bile and in milk. The demand for Cr has been growing as a result of factors commonly referred to as stressors, especially during different forms of nutritional, metabolic and physical strain. This review describes Cr metabolism, the different biological functions of Cr and symptoms of Cr deficiency.","Chromium as an essential nutrient: a review Abs: Chromium (Cr) has been studied since the end of the 19(th) century, when carcinogenic effects of hexavalent Cr were discovered. Essentiality of trivalent Cr was demonstrated in 1959; Cr3+ has been studied in humans and laboratory animals since the 1970s and it is only since the 1990s that Cr has been studied as an essential element in livestock animals with the same intensity. Trivalent chromium is essential to normal carbohydrate, lipid and protein metabolism. Chromium is biologically active as part of an oligopeptide - chromodulin - potentiating the effect of insulin by facilitating insulin binding to receptors at the cell surface. With chromium acting as a cofactor of insulin, Cr activity in the organism is parallel to insulin functions. Cr absorption is low, ranging between 0.4 and 2.0% for inorganic compounds while the availability of organic Cr is more than 10 times higher. Absorbed Cr circulates in blood bound to the beta-globulin plasma fraction and is transported to tissues bound to transferrin. Absorbed Cr is excreted primarily in urine, by glomerular filtration; a small amount is excreted through perspiration, bile and in milk. The demand for Cr has been growing as a result of factors commonly referred to as stressors, especially during different forms of nutritional, metabolic and physical strain. This review describes Cr metabolism, the different biological functions of Cr and symptoms of Cr deficiency."
1516687,YV and  Toropzev 1982,Chromosome damage induced in vivo by heavy metal ion detected by indirect testing,,Chromosome damage induced in vivo by heavy metal ion detected by indirect testing Abs: 
1516683,O'Brien et al. 1992,Studies of the kinetics of the reduction of chromate by glutathione and related thiols,"The reduction of chromate by glutathione, its mono- and diethyl esters, L-CySteine, 2-mercapto-propionic acid and mercapto-succinic acid has been studied. The empirical rate law k(obs) = ab[Thiol]2/(1 + b[Thiol]) is obeyed by all of these thiols, at neutral pH. No evidence could be obtained for a first-order pathway in glutathione under these conditions. These observations are used to comment on the stability of intermediates potentially important in explaining chromate toxicity.","Studies of the kinetics of the reduction of chromate by glutathione and related thiols Abs: The reduction of chromate by glutathione, its mono- and diethyl esters, L-CySteine, 2-mercapto-propionic acid and mercapto-succinic acid has been studied. The empirical rate law k(obs) = ab[Thiol]2/(1 + b[Thiol]) is obeyed by all of these thiols, at neutral pH. No evidence could be obtained for a first-order pathway in glutathione under these conditions. These observations are used to comment on the stability of intermediates potentially important in explaining chromate toxicity."
1516682,Matsui 1980,Evaluation of a Bacillus subtilis recombination-assay for the detection of mutagens which may occur in water environments,"HEEP COPYRIGHT: BIOL ABS. A recombination(rec)-deficient mutant of B. subtilis NIG-45 and a wild-type strain NIG-47 were used for mutagenicity testing. The NIG-45 strain is very sensitive to gamma-irradiation, UV-irradiation and chemical (drug) mutagens. The liquid-cultivation method was used rather than the plate-cultivation method; the liquid-cultivation method allows detection of very low concentrations of mutagens. Among the heavy metals tested, Cr6+ showed strong mutagenicity and Mn7+ showed weak mutagenicity. Cr6+ concentrations of 0.5 mg/l slowed the growth of NIG-45; the growth of NIG-47 was slowed by 1.0 mg/l Cr6+. When Cr6+ and mitomycin were applied together, an additive rather than a multiplicative level of mutations were induced. Hg, a non-mutagenic substance, did not enhance the mutagenicity of Cr6+ when these substances were simultaneously applied. Among test dyes, acridine orange, acridine yellow and methyl violet showed strong mutagenicity. Application of the target and hit theory to experimental results suggested that mitomycin and Cr6+ are 1-target-1-hit mutagens and that acridine orange and acridine yellow are 1-target-2-hits mutagens. A new term, the mean lethal concentration of chemical mutagens, was introduced to evaluate experimental results of 1-target-1-hit and 1-target-2-hits cases. This technique may be of value in the detection of mutagens which occur in water environments.","Evaluation of a Bacillus subtilis recombination-assay for the detection of mutagens which may occur in water environments Abs: HEEP COPYRIGHT: BIOL ABS. A recombination(rec)-deficient mutant of B. subtilis NIG-45 and a wild-type strain NIG-47 were used for mutagenicity testing. The NIG-45 strain is very sensitive to gamma-irradiation, UV-irradiation and chemical (drug) mutagens. The liquid-cultivation method was used rather than the plate-cultivation method; the liquid-cultivation method allows detection of very low concentrations of mutagens. Among the heavy metals tested, Cr6+ showed strong mutagenicity and Mn7+ showed weak mutagenicity. Cr6+ concentrations of 0.5 mg/l slowed the growth of NIG-45; the growth of NIG-47 was slowed by 1.0 mg/l Cr6+. When Cr6+ and mitomycin were applied together, an additive rather than a multiplicative level of mutations were induced. Hg, a non-mutagenic substance, did not enhance the mutagenicity of Cr6+ when these substances were simultaneously applied. Among test dyes, acridine orange, acridine yellow and methyl violet showed strong mutagenicity. Application of the target and hit theory to experimental results suggested that mitomycin and Cr6+ are 1-target-1-hit mutagens and that acridine orange and acridine yellow are 1-target-2-hits mutagens. A new term, the mean lethal concentration of chemical mutagens, was introduced to evaluate experimental results of 1-target-1-hit and 1-target-2-hits cases. This technique may be of value in the detection of mutagens which occur in water environments."
1516680,Lay and  Levina 1998,Activation of molecular oxygen during the reactions of Chromium(VI/V/IV) with biological reductants: Implications for chromium-induced genotoxicities,"The first systematic study on the roles of O-2 in the reactions of Cr(VI/V/IV) with major intracellular reductants, cysteine (1), glutathione (2), and ascorbic acid (3) as well as with vitamin E analogue Trolox (4), has been performed. The reactions of 1-3 with Cr(VI) (aqueous buffer solutions, pH = 4.5-7.5, 25 degrees C) led to a slow O-2 consumption (measured by a Clark oxygen electrode). The reactions of 1-3 with the relatively stable Cr(V) and Cr(IV) 2-ethyl-2-hydroxybutanoato complexes under the same conditions were accompanied by fast O-2 consumption. The O-2 consumption during the reactions of Cr(VI/V/IV) with 1-3 did not lead to a significant accumulation of H2O2 (determined with catalase). No significant O-2 consumption was detected for the reactions of Cr(VI/V/IV) with 4. To reveal the mechanisms of O-2 activation, the kinetics of the Cr(V/IV) reactions with 1-4 at pH 4.5 and 7.5 were studied by stopped-flow UV-visible spectrophotometry; and the kinetic data were processed by the global analysis method. The stoichiometries and products of these reactions were studied by UV-visible, CD, and EPR spectroscopies. The proposed mechanism of O-2 activation includes oxidations of 1-4 by Cr(V/IV) to produce organic radical intermediates, which then react with O-2 in chain processes. No evidence was found for the direct activation of O-2 by the Cr compounds. Implications of the proposed mechanism to the DNA damage induced by the Cr(VI) + reductant + O-2 systems have been discussed.","Activation of molecular oxygen during the reactions of Chromium(VI/V/IV) with biological reductants: Implications for chromium-induced genotoxicities Abs: The first systematic study on the roles of O-2 in the reactions of Cr(VI/V/IV) with major intracellular reductants, cysteine (1), glutathione (2), and ascorbic acid (3) as well as with vitamin E analogue Trolox (4), has been performed. The reactions of 1-3 with Cr(VI) (aqueous buffer solutions, pH = 4.5-7.5, 25 degrees C) led to a slow O-2 consumption (measured by a Clark oxygen electrode). The reactions of 1-3 with the relatively stable Cr(V) and Cr(IV) 2-ethyl-2-hydroxybutanoato complexes under the same conditions were accompanied by fast O-2 consumption. The O-2 consumption during the reactions of Cr(VI/V/IV) with 1-3 did not lead to a significant accumulation of H2O2 (determined with catalase). No significant O-2 consumption was detected for the reactions of Cr(VI/V/IV) with 4. To reveal the mechanisms of O-2 activation, the kinetics of the Cr(V/IV) reactions with 1-4 at pH 4.5 and 7.5 were studied by stopped-flow UV-visible spectrophotometry; and the kinetic data were processed by the global analysis method. The stoichiometries and products of these reactions were studied by UV-visible, CD, and EPR spectroscopies. The proposed mechanism of O-2 activation includes oxidations of 1-4 by Cr(V/IV) to produce organic radical intermediates, which then react with O-2 in chain processes. No evidence was found for the direct activation of O-2 by the Cr compounds. Implications of the proposed mechanism to the DNA damage induced by the Cr(VI) + reductant + O-2 systems have been discussed."
1516678,Fytianos 2001,Speciation analysis of heavy metals in natural waters: a review,"Metal speciation in natural waters is of increasing interest and importance because toxicity, bioavailability, environmental mobility, biogeochemical behavior, and potential risk in general are strongly dependent on the chemical species of metals. This paper provides an overview of the need for speciation of heavy metals in natural waters, the chemical and toxicological aspects of speciation, and the analytical procedures for separation and the different techniques for final determination that are used today. The trends and developments of speciation are also discussed. Finally, the case of chromium (Cr) was selected for a detailed presentation because the speciation of this metal has attracted a great deal of interest in view of the toxic properties of Cr(VI).","Speciation analysis of heavy metals in natural waters: a review Abs: Metal speciation in natural waters is of increasing interest and importance because toxicity, bioavailability, environmental mobility, biogeochemical behavior, and potential risk in general are strongly dependent on the chemical species of metals. This paper provides an overview of the need for speciation of heavy metals in natural waters, the chemical and toxicological aspects of speciation, and the analytical procedures for separation and the different techniques for final determination that are used today. The trends and developments of speciation are also discussed. Finally, the case of chromium (Cr) was selected for a detailed presentation because the speciation of this metal has attracted a great deal of interest in view of the toxic properties of Cr(VI)."
1516671,Zotter and  Licsko 1992,Removal of chromium-vi and other heavy metals from groundwaters in neutral and alkaline media,Biosis copyright: biol abs. rrm solid waste disposal groundwater pollution control nickel,Removal of chromium-vi and other heavy metals from groundwaters in neutral and alkaline media Abs: Biosis copyright: biol abs. rrm solid waste disposal groundwater pollution control nickel
1516670,Zhou et al. 1993,A process monitoring/controlling system for the treatment of wastewater containing chromium(VI),"BIOSIS COPYRIGHT: BIOL ABS. An advanced monitoring system for controlling the treatment process of wastewater containing chromium (VI) was developed using a flow method as a chemical sensing probe. In this system, the acquisition of monitoring information and the control of the treatment process is computer-controllable. By application of the system to control the end-point of redox-treatment, an accuracy and precision better than | 0.9% (n = 5) and a relative standard deviation smaller than 0.5% (n = 5) were found; furthermore, safe discharge of wastewater can be ensured without the addition of any coprecipitation reagents.","A process monitoring/controlling system for the treatment of wastewater containing chromium(VI) Abs: BIOSIS COPYRIGHT: BIOL ABS. An advanced monitoring system for controlling the treatment process of wastewater containing chromium (VI) was developed using a flow method as a chemical sensing probe. In this system, the acquisition of monitoring information and the control of the treatment process is computer-controllable. By application of the system to control the end-point of redox-treatment, an accuracy and precision better than | 0.9% (n = 5) and a relative standard deviation smaller than 0.5% (n = 5) were found; furthermore, safe discharge of wastewater can be ensured without the addition of any coprecipitation reagents."
1516669,Zavadil 1988,Evaluating the suitability of water for irrigation by acute toxicity tests with white mustard,Biosis copyright: biol abs. rrm chromium molybdenum copper manganese lead soil,Evaluating the suitability of water for irrigation by acute toxicity tests with white mustard Abs: Biosis copyright: biol abs. rrm chromium molybdenum copper manganese lead soil
1516668,Yang et al. 1994,Study on activated carbon in chromium-containing wastewater treatment by XPS,"BIOSIS COPYRIGHT: BIOL ABS. The mechanism of activated carbon treatment with chromium-containing wastewater by X-ray photoelectron spectroscopy (XPS) and that of adsorption and reduction reaction of the activated carbon with hexavalent chromium solution are presented in this paper. The XPS results show that at pH < 1, the activated carbon does not adsorb any chromium ion, and the main reaction is reduction process of Cr(VI); at 1 < pH < 6, both reduction process of Cr(VI) and adsorption process of Cr(VI) and Cr(III) occur on the carbon surface; at pH > 6, the main process is adsorption of the carbon to Cr(VI). The optimum range of treatment is at pH 3-6, in which removal efficiency of adsorption and reduction is relatively high. It demonstrates that the reduction mechanism is a heterogeneous acid catalysis process.","Study on activated carbon in chromium-containing wastewater treatment by XPS Abs: BIOSIS COPYRIGHT: BIOL ABS. The mechanism of activated carbon treatment with chromium-containing wastewater by X-ray photoelectron spectroscopy (XPS) and that of adsorption and reduction reaction of the activated carbon with hexavalent chromium solution are presented in this paper. The XPS results show that at pH < 1, the activated carbon does not adsorb any chromium ion, and the main reaction is reduction process of Cr(VI); at 1 < pH < 6, both reduction process of Cr(VI) and adsorption process of Cr(VI) and Cr(III) occur on the carbon surface; at pH > 6, the main process is adsorption of the carbon to Cr(VI). The optimum range of treatment is at pH 3-6, in which removal efficiency of adsorption and reduction is relatively high. It demonstrates that the reduction mechanism is a heterogeneous acid catalysis process."
1516667,Wong and  Chang 1992,Effects of bi- and trimetallic combinations of heavy metal ions on inorganic nitrogen and phosphorus uptake in Chlorella,"BIOSIS COPYRIGHT: BIOL ABS. Effects of bi- and trimetallic combinations of three heavy metal ions, namely, copper (Cu2+), chromium (Cr6+) and nickel (Ni2+), on the growth rate, and inorganic nitrogen and phosphorus uptake in Chlorella were determined. Results indicated that the order of toxicity of the three heavy metal ions on the growth rate, and NH4+, NO3--N and PO43--P uptake by the alga was Cu2+ > Cr6+ > Ni2+. The presence of a sublethal concentration of one heavy metal ion synergistically enhanced the toxicity of another heavy metal ion on the growth and inorganic nitrogen and phosphorus uptake.","Effects of bi- and trimetallic combinations of heavy metal ions on inorganic nitrogen and phosphorus uptake in Chlorella Abs: BIOSIS COPYRIGHT: BIOL ABS. Effects of bi- and trimetallic combinations of three heavy metal ions, namely, copper (Cu2+), chromium (Cr6+) and nickel (Ni2+), on the growth rate, and inorganic nitrogen and phosphorus uptake in Chlorella were determined. Results indicated that the order of toxicity of the three heavy metal ions on the growth rate, and NH4+, NO3--N and PO43--P uptake by the alga was Cu2+ > Cr6+ > Ni2+. The presence of a sublethal concentration of one heavy metal ion synergistically enhanced the toxicity of another heavy metal ion on the growth and inorganic nitrogen and phosphorus uptake."
1516665,Wittbrodt and  Palmer 1994,Reduction of crvi by soil fulvic acid,Biosis copyright: biol abs. rrm meeting abstract soil pollution batch reactors rate limiting step,Reduction of crvi by soil fulvic acid Abs: Biosis copyright: biol abs. rrm meeting abstract soil pollution batch reactors rate limiting step
1516664,Wisbey et al. 1987,Application of pvd titanium nitride coating to cobalt-chromium-molybdenum based surgical implants,Biosis copyright: biol abs. rrm joint arthroplasty metal ion release biocompatibility physical vapor deposition medical technology,Application of pvd titanium nitride coating to cobalt-chromium-molybdenum based surgical implants Abs: Biosis copyright: biol abs. rrm joint arthroplasty metal ion release biocompatibility physical vapor deposition medical technology
1516663,Wimberley and  Tittlebaum 1989,Chromium removal by activated sludge,Biosis copyright: biol abs. rrm human industrial wastewater treatment groundwater contamination hazardous constituents epa carcinogenicity,Chromium removal by activated sludge Abs: Biosis copyright: biol abs. rrm human industrial wastewater treatment groundwater contamination hazardous constituents epa carcinogenicity
1516662,Wiegand et al. 1986,Possible involvement of the anion transport system band-3-protein in fast chromium-vi uptake of human red blood cells,Biosis copyright: biol abs. rrm abstract chromium toxicity,Possible involvement of the anion transport system band-3-protein in fast chromium-vi uptake of human red blood cells Abs: Biosis copyright: biol abs. rrm abstract chromium toxicity
1516661,White et al. 1990,Measurement and interpretation of low levels of dissolved oxygen in ground water,"BIOSIS COPYRIGHT: BIOL ABS. A Rhodazine-D colorimetric technique was adpated to measure low-level dissolved oxygen concentrations in ground water. Prepared samples containing between 0 and 8,0 mumoles 1-1 dissolved oxygen in equilibrium with known gas mixtures produced linear spectrophotometric absorbance with a lower detection limit of 0.2 mumol l-1. Excellent reproducibility was found for solutions ranging in composition form deionized water to sea water with chemical interferences detected only for easily reduced metal species such as ferric ion, cupric ion, and hexavalent chromium. Such effects were correctable based on parallel reactions stoichiometries relative to oxygen. The technique, coupled with a downhole wire line tool, permitted low-level monitoring of dissolved oxygen in wells at the selenium-contaminated Kesterson Reservoir in California. Results indicated a close association between low but measurable dissolved oxygen concentrations and mobility of oxidized forms of selenium in the","Measurement and interpretation of low levels of dissolved oxygen in ground water Abs: BIOSIS COPYRIGHT: BIOL ABS. A Rhodazine-D colorimetric technique was adpated to measure low-level dissolved oxygen concentrations in ground water. Prepared samples containing between 0 and 8,0 mumoles 1-1 dissolved oxygen in equilibrium with known gas mixtures produced linear spectrophotometric absorbance with a lower detection limit of 0.2 mumol l-1. Excellent reproducibility was found for solutions ranging in composition form deionized water to sea water with chemical interferences detected only for easily reduced metal species such as ferric ion, cupric ion, and hexavalent chromium. Such effects were correctable based on parallel reactions stoichiometries relative to oxygen. The technique, coupled with a downhole wire line tool, permitted low-level monitoring of dissolved oxygen in wells at the selenium-contaminated Kesterson Reservoir in California. Results indicated a close association between low but measurable dissolved oxygen concentrations and mobility of oxidized forms of selenium in the"
1516660,Weigand and  Ottenwaelder 1986,The chromium content of human red blood cells a new selective parameter for the biological monitoring of hexavalent chromium compounds,Biosis copyright: biol abs. rrm abstract toxicity carcinogens respiratory cancer,The chromium content of human red blood cells a new selective parameter for the biological monitoring of hexavalent chromium compounds Abs: Biosis copyright: biol abs. rrm abstract toxicity carcinogens respiratory cancer
1516659,Wang 1994,Rice seed toxicity tests for organic and inorganic substances,"BIOSIS COPYRIGHT: BIOL ABS. Plant seed toxicity tests can be used to evaluate hazardous waste sites and to assess toxicity of complex effluents and industrial chemicals. Conventional plant seed toxicity tests are performed using culture dishes containing filter paper. Some reports indicate that filter papers might interfere with the toxicity of inorganic substances. In this study, a plastic seed tray was used. Rice was used as the test species. A comparison of results in the literature and this study revealed that variation of test species, methods, exposure duration, and other factors may affect the test results. The results of this study showed that the order of decreasing toxicity of metal ions was Cu > Ag > Ni > Cd > Cr(VI) > Pb > Zn > Mn > NaF for rice. The test results were similar to those reported in the literature for lettuce Ag > Ni > Cd,Cu > Cr(VI) > Zn > Mn, millet Cu,Ni > Cd > Cr(VI) > Zn > Mn, and ryegrass Cu > Ni > Mn Pb > Cd > Zn > Al > Hg > Cr > Fe. The or","Rice seed toxicity tests for organic and inorganic substances Abs: BIOSIS COPYRIGHT: BIOL ABS. Plant seed toxicity tests can be used to evaluate hazardous waste sites and to assess toxicity of complex effluents and industrial chemicals. Conventional plant seed toxicity tests are performed using culture dishes containing filter paper. Some reports indicate that filter papers might interfere with the toxicity of inorganic substances. In this study, a plastic seed tray was used. Rice was used as the test species. A comparison of results in the literature and this study revealed that variation of test species, methods, exposure duration, and other factors may affect the test results. The results of this study showed that the order of decreasing toxicity of metal ions was Cu > Ag > Ni > Cd > Cr(VI) > Pb > Zn > Mn > NaF for rice. The test results were similar to those reported in the literature for lettuce Ag > Ni > Cd,Cu > Cr(VI) > Zn > Mn, millet Cu,Ni > Cd > Cr(VI) > Zn > Mn, and ryegrass Cu > Ni > Mn Pb > Cd > Zn > Al > Hg > Cr > Fe. The or"
1516658,Wang 1993,"Comparative rice seed toxicity tests using filter paper, Growth Pouch, and seed tray methods","BIOSIS COPYRIGHT: BIOL ABS. Paper substrate, especially circular filter paper placed inside a Petri dish, has long been used for the plant seed toxicity test (PSTT). Although this method is simple and inexpensive, recent evidence indicates that it gives results that are significantly different from those obtained using a method that does not involve paper, especially when testing metal cations. The study compared PSTT using three methods: filter paper, Growth Pouch-TM, and seed tray. The Growth Pouch-TM is a commercially available device. The seed tray is a newly designed plastic receptable placed inside a Petri dish. The results of the Growth Pouch-TM method showed no toxic effects on rice for Ag up to 40 mg L-1 and Cd up to 20 mg L-1. Using the seed tray method, IC50 (50% inhibitory effect concentration) values were 0.55 and 1.4 mg L-1 for Ag and Cd, respectively. Although results of filter paper and seed tray methods were nearly identical for NaF, Cr(VI), and phenol, the toxicities of cations Ag MH - BIOCHEMISTRY","Comparative rice seed toxicity tests using filter paper, Growth Pouch, and seed tray methods Abs: BIOSIS COPYRIGHT: BIOL ABS. Paper substrate, especially circular filter paper placed inside a Petri dish, has long been used for the plant seed toxicity test (PSTT). Although this method is simple and inexpensive, recent evidence indicates that it gives results that are significantly different from those obtained using a method that does not involve paper, especially when testing metal cations. The study compared PSTT using three methods: filter paper, Growth Pouch-TM, and seed tray. The Growth Pouch-TM is a commercially available device. The seed tray is a newly designed plastic receptable placed inside a Petri dish. The results of the Growth Pouch-TM method showed no toxic effects on rice for Ag up to 40 mg L-1 and Cd up to 20 mg L-1. Using the seed tray method, IC50 (50% inhibitory effect concentration) values were 0.55 and 1.4 mg L-1 for Ag and Cd, respectively. Although results of filter paper and seed tray methods were nearly identical for NaF, Cr(VI), and phenol, the toxicities of cations Ag MH - BIOCHEMISTRY"
1516657,Wang 1987,Root elongation method for toxicity testing of organic and inorganic pollutants,Biosis copyright: biol abs. rrm cucumber lettuce millet phytotoxicity test heavy metal phenolic compounds,Root elongation method for toxicity testing of organic and inorganic pollutants Abs: Biosis copyright: biol abs. rrm cucumber lettuce millet phytotoxicity test heavy metal phenolic compounds
1516656,Wang 1986,"The effect of river water on phytotoxicity of barium, cadmium and chromium","BIOSIS COPYRIGHT: BIOL ABS. A 75 liter sample of Illinois River water was taken on 6 December 1982 for comparison with deionised water to test metal toxicity to duck weed. Barium, cadmium and chromium (VI) were tested. There were three different types of results. Ba is moderately toxic in deionised water and non-toxic in river water. Cd is extremely toxic in deionised water and also substantially toxic, though somewhat less so, in river water. Cr(VI) toxicity in river water is more or less identical to that in deionised water. These results point out the importance of natural water in regulating heavy metal toxicity.","The effect of river water on phytotoxicity of barium, cadmium and chromium Abs: BIOSIS COPYRIGHT: BIOL ABS. A 75 liter sample of Illinois River water was taken on 6 December 1982 for comparison with deionised water to test metal toxicity to duck weed. Barium, cadmium and chromium (VI) were tested. There were three different types of results. Ba is moderately toxic in deionised water and non-toxic in river water. Cd is extremely toxic in deionised water and also substantially toxic, though somewhat less so, in river water. Cr(VI) toxicity in river water is more or less identical to that in deionised water. These results point out the importance of natural water in regulating heavy metal toxicity."
1516655,Wood and  Mcatamney 1994,The use of macrophytes in bioremediation,Biosis copyright: biol abs. rrm literature review phragmites-australis plant biotechnology wetlands toxicity waste disposal waste water treatment methods reedbed technology,The use of macrophytes in bioremediation Abs: Biosis copyright: biol abs. rrm literature review phragmites-australis plant biotechnology wetlands toxicity waste disposal waste water treatment methods reedbed technology
1516654,Wittbrodt and  Palmer 1995,Reduction of Cr(VI) in the Presence of Excess Soil Fulvic Acid,"BIOSIS COPYRIGHT: BIOL ABS. The rate of hexavalent chromium reduction by a soil fulvic acid (SFA) was measured in aqueous solutions where concentrations of Cr(VI), H+, and SFA were independently varied. Rates of reduction increase strongly with decreasing pH. Typical Cr(VI)-SFA reactions display a nonlinear reduction of Cr(VI) with time that cannot adequately be modeled by either first-order or second-order rate equations. An empirical rate equation that treats the SFA as a continuum of reactive groups which reduce Cr(VI) at varying rates adequately describes the effects of solution parameters on the rates of Cr(VI) reduction. The rate equation is R = kr(HCrO4-)(SFA)(Cr(VI))op(H+)q where (Cr(VI))o is the initial Cr(VI) concentration. The rate coefficient (kr) varies with the fraction (Xe) of SFA reducing equivalents oxidized and can be written as kXen, where k is (4.27 | 0.68)ters p and q are 0.47 | 0.11 and 0.45 | 0.03, respectively. The rate equation is based on experiments where up to 5% of the","Reduction of Cr(VI) in the Presence of Excess Soil Fulvic Acid Abs: BIOSIS COPYRIGHT: BIOL ABS. The rate of hexavalent chromium reduction by a soil fulvic acid (SFA) was measured in aqueous solutions where concentrations of Cr(VI), H+, and SFA were independently varied. Rates of reduction increase strongly with decreasing pH. Typical Cr(VI)-SFA reactions display a nonlinear reduction of Cr(VI) with time that cannot adequately be modeled by either first-order or second-order rate equations. An empirical rate equation that treats the SFA as a continuum of reactive groups which reduce Cr(VI) at varying rates adequately describes the effects of solution parameters on the rates of Cr(VI) reduction. The rate equation is R = kr(HCrO4-)(SFA)(Cr(VI))op(H+)q where (Cr(VI))o is the initial Cr(VI) concentration. The rate coefficient (kr) varies with the fraction (Xe) of SFA reducing equivalents oxidized and can be written as kXen, where k is (4.27 | 0.68)ters p and q are 0.47 | 0.11 and 0.45 | 0.03, respectively. The rate equation is based on experiments where up to 5% of the"
1516653,Zouboulis et al. 1995,Removal of hexavalent chromium anions from solutions by pyrite fines,"BIOSIS COPYRIGHT: BIOL ABS. Bench scale experiments were conducted in the laboratory, aiming to the removal of hexavalent chromium from aqueous solutions, by dispersed pyrite fine particles. Pyrite (iron sulphide mineral), was found to act as an efficient Cr(VI) reducing agent. The resulted hydroxo-Cr(III) species were found to be precipitated (and removed) onto the pyrite particles. The process mechanism was also examined by zeta-potential measurements and speciation studies. Promising results were obtained at highly acidic pH values (around 1-2), showing an interesting aspect of fine (solid waste) mineral particles utilization, in the removal of a priority pollutant.","Removal of hexavalent chromium anions from solutions by pyrite fines Abs: BIOSIS COPYRIGHT: BIOL ABS. Bench scale experiments were conducted in the laboratory, aiming to the removal of hexavalent chromium from aqueous solutions, by dispersed pyrite fine particles. Pyrite (iron sulphide mineral), was found to act as an efficient Cr(VI) reducing agent. The resulted hydroxo-Cr(III) species were found to be precipitated (and removed) onto the pyrite particles. The process mechanism was also examined by zeta-potential measurements and speciation studies. Promising results were obtained at highly acidic pH values (around 1-2), showing an interesting aspect of fine (solid waste) mineral particles utilization, in the removal of a priority pollutant."
1516652,Weeks 1995,Controlling occupational health hazards in construction,Biosis copyright: biol abs. rrm literature review human airborne hazards dermatologic chemical hazards lung cancer gastric cancer leukemia lymphoma metals heat cold electrical shock noise radiation,Controlling occupational health hazards in construction Abs: Biosis copyright: biol abs. rrm literature review human airborne hazards dermatologic chemical hazards lung cancer gastric cancer leukemia lymphoma metals heat cold electrical shock noise radiation
1516651,Wang and  Xiao 1995,Factors affecting hexavalent chromium reduction in pure cultures of bacteria,"BIOSIS COPYRIGHT: BIOL ABS. Batch studies were conducted to evaluate the effect of environmental factors on the rate of Cr(VI) reduction by two organisms, Bacillus sp. (a new isolate), and Pseudomonas fluorescens LB 300. Both organisms utilized glucose for Cr(VI) reduction under aerobic conditions. Higher Cr(VI) reduction rates were obtained with higher initial cell concentrations, but the specific rate (normalized against initial cell concentration), was higher at lower initial cell concentrations. The rate of Cr(VI) reduction by Bacillus sp. increased with initial Cr(VI) concentrations ranging from 20 to 70mg/l and decreased at higher concentrations. The rate of Cr(VI) reduction by LB 300 steadily increased with the initial Cr(VI) concentrations over the entire test range of 20-100 mg/l Cr(VI). Further studies with the new isolate, Bacillus sp., showed that neither sulfate nor nitrate affected Cr(VI) reduction. Also no correlations were found between the rate of Cr(VI) reduction and the redox po","Factors affecting hexavalent chromium reduction in pure cultures of bacteria Abs: BIOSIS COPYRIGHT: BIOL ABS. Batch studies were conducted to evaluate the effect of environmental factors on the rate of Cr(VI) reduction by two organisms, Bacillus sp. (a new isolate), and Pseudomonas fluorescens LB 300. Both organisms utilized glucose for Cr(VI) reduction under aerobic conditions. Higher Cr(VI) reduction rates were obtained with higher initial cell concentrations, but the specific rate (normalized against initial cell concentration), was higher at lower initial cell concentrations. The rate of Cr(VI) reduction by Bacillus sp. increased with initial Cr(VI) concentrations ranging from 20 to 70mg/l and decreased at higher concentrations. The rate of Cr(VI) reduction by LB 300 steadily increased with the initial Cr(VI) concentrations over the entire test range of 20-100 mg/l Cr(VI). Further studies with the new isolate, Bacillus sp., showed that neither sulfate nor nitrate affected Cr(VI) reduction. Also no correlations were found between the rate of Cr(VI) reduction and the redox po"
1516650,Zhang et al. 1996,"Enhancement of Fe(III), Co(III), and Cr(VI) reduction at elevated temperatures and by a thermophilic bacterium","BIOSIS COPYRIGHT: BIOL ABS. An unusual thermophilic bacterium has been isolated from deep subsurface sediments and tested for its ability to enhance Fe(III), Co(III), and Cr(VI) reduction. Without the bacterium, abiotic metal reduction was insignificant at temperatures below 45êC, but became a major process at 75êC. Addition of the bacterium enhanced the reduction of these metals up to fourfold, probably by nonspecific mechanisms. This study demonstrates abiotic and biotic metal reduction under organic-rich thermic conditions, and suggests that thermally and/or biologically enhanced metal reduction may provide an alternative for remediating metal contamination.","Enhancement of Fe(III), Co(III), and Cr(VI) reduction at elevated temperatures and by a thermophilic bacterium Abs: BIOSIS COPYRIGHT: BIOL ABS. An unusual thermophilic bacterium has been isolated from deep subsurface sediments and tested for its ability to enhance Fe(III), Co(III), and Cr(VI) reduction. Without the bacterium, abiotic metal reduction was insignificant at temperatures below 45êC, but became a major process at 75êC. Addition of the bacterium enhanced the reduction of these metals up to fourfold, probably by nonspecific mechanisms. This study demonstrates abiotic and biotic metal reduction under organic-rich thermic conditions, and suggests that thermally and/or biologically enhanced metal reduction may provide an alternative for remediating metal contamination."
1516649,Wang et al. 1997,Bioavailability of Cr(III) and Cr(VI) to marine mussels from solute and particulate pathways,"BIOSIS COPYRIGHT: BIOL ABS. Mussels have been extensively used as biological monitors of coastal contamination. This study measured the assimilation efficiencies (AEs) of Cr(III) and Cr(VI) in the mussel Mytilus edulis from ingested food, uptake from the dissolved phase, and the physiological efflux rates following uptake. A bioenergetic-based kinetic model was then employed to determine the relative contributions of different Cr species and their accumulation pathways to the overall concentration of Cr in mussels. The concentration factors of Cr(III) in four diverse marine phytoplankters ranged between 104 and 105, whereas for Cr(VI) they were 2 to 5I) to Cr(III) was observed in coastal sediments. AEs of Cr(III) in mussels from ingested sediments were consistently < 1%, whereas the AEs of Cr(VI) from ingested phytoplankton were 1-10%. The uptake rate of Cr(VI) from the dissolved phase was 3 times higher than Cr(III). The efflux rate constant was 0.011 d-1 for mussels following 7 d dissolved u","Bioavailability of Cr(III) and Cr(VI) to marine mussels from solute and particulate pathways Abs: BIOSIS COPYRIGHT: BIOL ABS. Mussels have been extensively used as biological monitors of coastal contamination. This study measured the assimilation efficiencies (AEs) of Cr(III) and Cr(VI) in the mussel Mytilus edulis from ingested food, uptake from the dissolved phase, and the physiological efflux rates following uptake. A bioenergetic-based kinetic model was then employed to determine the relative contributions of different Cr species and their accumulation pathways to the overall concentration of Cr in mussels. The concentration factors of Cr(III) in four diverse marine phytoplankters ranged between 104 and 105, whereas for Cr(VI) they were 2 to 5I) to Cr(III) was observed in coastal sediments. AEs of Cr(III) in mussels from ingested sediments were consistently < 1%, whereas the AEs of Cr(VI) from ingested phytoplankton were 1-10%. The uptake rate of Cr(VI) from the dissolved phase was 3 times higher than Cr(III). The efflux rate constant was 0.011 d-1 for mussels following 7 d dissolved u"
1516648,Wang and  Shen 1997,Modelling Cr(VI) reduction by pure bacterial cultures,"BIOSIS COPYRIGHT: BIOL ABS. Cr(VI) reduction data obtained with three bacterial species (Escherichia coli ATCC 33456, Bacillus sp., Pseudomonas fluorescens LB 300) were analyzed using an enzyme-based kinetic model. The model was developed by incorporating enzyme kinetics and a finite Cr(VI) reduction capacity to illustrate toxic effects of Cr(VI). The model was also used to analyze Cr(VI) reduction data taken from the literature for two other Cr(VI)-reducing species (Desulfovibrio vulgaris ATCC 29579, and Pseudomonas ambigua G-1). Although four different genera of bacteria were involved, the model was found to be capable of describing Cr(VI) reduction. The finite capacity indicates the maximum amount of Cr(VI) that a batch culture can reduce and it was explicitly demonstrated regardless of subsequent cell growth. The lost of Cr(VI) reduction capacity in bacterial cells may be attributed to the mutagenic and toxic effects of Cr(VI). The batch cultures reduced Cr(VI) at rates which decreased progre MH - BIOCHEMISTRY","Modelling Cr(VI) reduction by pure bacterial cultures Abs: BIOSIS COPYRIGHT: BIOL ABS. Cr(VI) reduction data obtained with three bacterial species (Escherichia coli ATCC 33456, Bacillus sp., Pseudomonas fluorescens LB 300) were analyzed using an enzyme-based kinetic model. The model was developed by incorporating enzyme kinetics and a finite Cr(VI) reduction capacity to illustrate toxic effects of Cr(VI). The model was also used to analyze Cr(VI) reduction data taken from the literature for two other Cr(VI)-reducing species (Desulfovibrio vulgaris ATCC 29579, and Pseudomonas ambigua G-1). Although four different genera of bacteria were involved, the model was found to be capable of describing Cr(VI) reduction. The finite capacity indicates the maximum amount of Cr(VI) that a batch culture can reduce and it was explicitly demonstrated regardless of subsequent cell growth. The lost of Cr(VI) reduction capacity in bacterial cells may be attributed to the mutagenic and toxic effects of Cr(VI). The batch cultures reduced Cr(VI) at rates which decreased progre MH - BIOCHEMISTRY"
1516647,Zhitkovich et al. 1997,Ternary dna adducts formed by carcinogenic cr compounds in vitro formation and mutagenic potential,Biosis copyright: biol abs. rrm meeting abstract tumor biology toxicology chromium iii carcinogens chromium vi dna adducts in-vitro mutagenic potential biochemistry and biophysics,Ternary dna adducts formed by carcinogenic cr compounds in vitro formation and mutagenic potential Abs: Biosis copyright: biol abs. rrm meeting abstract tumor biology toxicology chromium iii carcinogens chromium vi dna adducts in-vitro mutagenic potential biochemistry and biophysics
1516646,Zhu et al. 1997,"Study on the contamination of fracture-karst water in Boshan District, China","BIOSIS COPYRIGHT: BIOL ABS. Boshan is an industrial city in the center of Shandong Province where ground water is the only source for the urban water supply. The major water resource is fracture-karst water in the middle Ordovician carbonate rocks. Based on the hydrogeological investigation and mapping in this area we studied the geologic and hydrogeologic settings, the major pollution sources and the pathways of contamination, the principal contaminants, and their spatial distribution in ground water. The ground-water quality has also been estimated by the fuzzy mathematic method. The geostatistical method, such as the kriging method, was taken to simulate spatial distribution of the contaminants. The grey system method was adopted to forecast future contamination. An attempt at the remediation of Cr6+ contamination in fracture-karst water was also discussed. Finally, some proposals for the protection of the ground-water environment in Boshan District are offered.","Study on the contamination of fracture-karst water in Boshan District, China Abs: BIOSIS COPYRIGHT: BIOL ABS. Boshan is an industrial city in the center of Shandong Province where ground water is the only source for the urban water supply. The major water resource is fracture-karst water in the middle Ordovician carbonate rocks. Based on the hydrogeological investigation and mapping in this area we studied the geologic and hydrogeologic settings, the major pollution sources and the pathways of contamination, the principal contaminants, and their spatial distribution in ground water. The ground-water quality has also been estimated by the fuzzy mathematic method. The geostatistical method, such as the kriging method, was taken to simulate spatial distribution of the contaminants. The grey system method was adopted to forecast future contamination. An attempt at the remediation of Cr6+ contamination in fracture-karst water was also discussed. Finally, some proposals for the protection of the ground-water environment in Boshan District are offered."
1516645,Zoorob and  Caruso 1997,Speciation of chromium dyes by high-performance liquid chromatography with inductively coupled plasma mass spectrometric detection,"BIOSIS COPYRIGHT: BIOL ABS. High-performance liquid chromatography (HPLC) coupled to inductively coupled plasma mass spectrometry (ICP-MS) was employed for the separation and detection of chromium species in azo dyes, Acid Blue 158 and Acid Blue 193; mainly Cr(III) and Cr(VI). The dyes were first analyzed for total metal content using ICP-MS and their stability in solution was studied by measuring their absorbance through a range of pH values. Then an isocratic chromatographic method employing reversed-phase liquid chromatography with mass spectrometric detection was developed. Applying this method to the separation of these dyes, the absolute detection limits of Acid Blue 158 and 193 were 1 and 5 ng respectively. Additionally, Acid Blue 158 did not contain any unbound chromium species. On the other hand, Acid Blue 193 contained uncomplexed and potentially bioavailable Cr(III). Acid Blue 193 did not have any toxic Cr(VI) present in the samples.","Speciation of chromium dyes by high-performance liquid chromatography with inductively coupled plasma mass spectrometric detection Abs: BIOSIS COPYRIGHT: BIOL ABS. High-performance liquid chromatography (HPLC) coupled to inductively coupled plasma mass spectrometry (ICP-MS) was employed for the separation and detection of chromium species in azo dyes, Acid Blue 158 and Acid Blue 193; mainly Cr(III) and Cr(VI). The dyes were first analyzed for total metal content using ICP-MS and their stability in solution was studied by measuring their absorbance through a range of pH values. Then an isocratic chromatographic method employing reversed-phase liquid chromatography with mass spectrometric detection was developed. Applying this method to the separation of these dyes, the absolute detection limits of Acid Blue 158 and 193 were 1 and 5 ng respectively. Additionally, Acid Blue 158 did not contain any unbound chromium species. On the other hand, Acid Blue 193 contained uncomplexed and potentially bioavailable Cr(III). Acid Blue 193 did not have any toxic Cr(VI) present in the samples."
1516644,Wrobel et al. 1997,Enhanced spectrophotometric determination of chromium (VI) with diphenylcarbazide using internal standard and derivative spectrophotometry,"BIOSIS COPYRIGHT: BIOL ABS. In the present work, erioglaucine A was applied as internal standard to enhanced spectrophotometric determination of chromium (VI) with diphenylcarbazide. The following procedure was used: (1) addition of internal standard and formation of ion pairs of Cr (VI) with benzyltributylammonium bromide (BTAB) (sample volume 100 ml), (2) extraction to 10 ml of methylene chloride, (3) evaporation in nitrogen stream, and (4) redissolution in a micro-volume with addition of diphenylcarbazide for color development (final volume 200 mul). The preconcentration factor achieved was about 400 and it was shown that, using internal standard, the analytical errors due to sample treatment were reduced. The analytical signals for chromium and internal standard were obtained at 591.30 and 653.50 nm from first derivative spectra, normalized against 1 D653.50nm. The analytical characteristics evaluated were: detection limit = 0.06 mug l-1, quantification limit = 0.19 mug l-1, precision for 1 m","Enhanced spectrophotometric determination of chromium (VI) with diphenylcarbazide using internal standard and derivative spectrophotometry Abs: BIOSIS COPYRIGHT: BIOL ABS. In the present work, erioglaucine A was applied as internal standard to enhanced spectrophotometric determination of chromium (VI) with diphenylcarbazide. The following procedure was used: (1) addition of internal standard and formation of ion pairs of Cr (VI) with benzyltributylammonium bromide (BTAB) (sample volume 100 ml), (2) extraction to 10 ml of methylene chloride, (3) evaporation in nitrogen stream, and (4) redissolution in a micro-volume with addition of diphenylcarbazide for color development (final volume 200 mul). The preconcentration factor achieved was about 400 and it was shown that, using internal standard, the analytical errors due to sample treatment were reduced. The analytical signals for chromium and internal standard were obtained at 591.30 and 653.50 nm from first derivative spectra, normalized against 1 D653.50nm. The analytical characteristics evaluated were: detection limit = 0.06 mug l-1, quantification limit = 0.19 mug l-1, precision for 1 m"
1516643,Whitlock and  Galitz 1997,Effects of chromite ore-processing residue on concrete structures,"BIOSIS COPYRIGHT: BIOL ABS. In the 1960s, a number of industrial and commercial buildings in the Kearny, New Jersey, area were constructed on or adjacent to locally produced chromite ore-processing residue (COPR). This residue, which has the properties of a sandy/silty soil, was used as a fill material to reclaim the indigenous swampy ground conditions, known locally as the ""Meadowlands"". Generally, the fill stratum is between 4 and 10 ft thick and contains varying amounts of hexavalent and trivalent chromium. It has been alleged that chromium causes damage to structures through various mechanisms. The authors have considered these allegations through research and review of the literature, field invesgations of over 100, structures built on or near COPR, field studies involving concrete exposed to COPR, and laboratory studies. The results of the investigations and studies are discussed in this article. It has been found that the existing distress on building and bridge structures is no different f","Effects of chromite ore-processing residue on concrete structures Abs: BIOSIS COPYRIGHT: BIOL ABS. In the 1960s, a number of industrial and commercial buildings in the Kearny, New Jersey, area were constructed on or adjacent to locally produced chromite ore-processing residue (COPR). This residue, which has the properties of a sandy/silty soil, was used as a fill material to reclaim the indigenous swampy ground conditions, known locally as the ""Meadowlands"". Generally, the fill stratum is between 4 and 10 ft thick and contains varying amounts of hexavalent and trivalent chromium. It has been alleged that chromium causes damage to structures through various mechanisms. The authors have considered these allegations through research and review of the literature, field invesgations of over 100, structures built on or near COPR, field studies involving concrete exposed to COPR, and laboratory studies. The results of the investigations and studies are discussed in this article. It has been found that the existing distress on building and bridge structures is no different f"
1516642,Zhao et al. 1998,Chromotropic acid as a reagent for ultraviolet spectrophotometric determination of hexavalent chromium in water,BIOSIS COPYRIGHT: BIOL ABS. A new ultraviolet spectrophotometric method for hexavalent chromium in water based on the oxidation of chromotropic acid by Cr(VI) in 0.12 mol/liter HCl medium is described. The molar absorptivity is 1.761 cm-1. The detection limit is 0.024 mug ml-1 Cr. This sensitive and very simple ultraviolet spectrophotometric method for microquantitative determination of Cr(VI) in water has good precision and accuracy.,Chromotropic acid as a reagent for ultraviolet spectrophotometric determination of hexavalent chromium in water Abs: BIOSIS COPYRIGHT: BIOL ABS. A new ultraviolet spectrophotometric method for hexavalent chromium in water based on the oxidation of chromotropic acid by Cr(VI) in 0.12 mol/liter HCl medium is described. The molar absorptivity is 1.761 cm-1. The detection limit is 0.024 mug ml-1 Cr. This sensitive and very simple ultraviolet spectrophotometric method for microquantitative determination of Cr(VI) in water has good precision and accuracy.
1516641,Zhao and  Duncan 1997,Column sorption and desorption of hexavalent chromium form aqueous solution and electroplating effluent using Azolla filiculoides,"BIOSIS COPYRIGHT: BIOL ABS. Dried aquatic fern, Azolla filiculoides, was used in column operations for removal of hexavalent chromium from aqueous solutions and electroplating effluent at acidic pHs. The results show that the optimum chromium uptake (41.5 mg/g) at 60% saturation of the biomass was obtained at a pH of 2.5. The saturated biomass can be regenerated in situ with 0.5M Na2S2O5/0.5M HCl, but the regeneration efficiency is only about 50%. Alternatively, removal of trivalent chromium by Azolla biomass at a pH value of 5.0 appeared promising with a chromium uptake of 25.5 mg/g. The sorbent was successfully regenerated in 0.5N H2SO4 with a recovery of 80%. The column biomass was then used repeatedly for up to five cycles with regeneration efficiencies of up to 90%.","Column sorption and desorption of hexavalent chromium form aqueous solution and electroplating effluent using Azolla filiculoides Abs: BIOSIS COPYRIGHT: BIOL ABS. Dried aquatic fern, Azolla filiculoides, was used in column operations for removal of hexavalent chromium from aqueous solutions and electroplating effluent at acidic pHs. The results show that the optimum chromium uptake (41.5 mg/g) at 60% saturation of the biomass was obtained at a pH of 2.5. The saturated biomass can be regenerated in situ with 0.5M Na2S2O5/0.5M HCl, but the regeneration efficiency is only about 50%. Alternatively, removal of trivalent chromium by Azolla biomass at a pH value of 5.0 appeared promising with a chromium uptake of 25.5 mg/g. The sorbent was successfully regenerated in 0.5N H2SO4 with a recovery of 80%. The column biomass was then used repeatedly for up to five cycles with regeneration efficiencies of up to 90%."
1516640,Wood and  Prather 1998,Time-of-flight mass spectrometry methods for real time analysis of individual aerosol particles,"BIOSIS COPYRIGHT: BIOL ABS. Recent instrumental developments allow for the analysis of single particles in real time. The techniques discussed in this review couple time-of-flight mass spectrometry for determining the chemical composition of individual aerosol particles with some form of optical particle detection. Applications to be discussed include the study of laboratory-generated particles and ambient particle sampling, including field studies aimed at measuring the temporal profiles of atmospheric particles.","Time-of-flight mass spectrometry methods for real time analysis of individual aerosol particles Abs: BIOSIS COPYRIGHT: BIOL ABS. Recent instrumental developments allow for the analysis of single particles in real time. The techniques discussed in this review couple time-of-flight mass spectrometry for determining the chemical composition of individual aerosol particles with some form of optical particle detection. Applications to be discussed include the study of laboratory-generated particles and ambient particle sampling, including field studies aimed at measuring the temporal profiles of atmospheric particles."
1516639,Zhao and  Duncan 1998,Column sorption of Cr(VI) from electroplating effluent using formaldehyde cross-linked Saccharomyces cerevisiae,"BIOSIS COPYRIGHT: BIOL ABS. Pellets of Saccharomyces cerevisiae, cross-linked by 13% (w/v) formaldehyde, were used in fixed-bed columns to remove Cr(VI) from electroplating rinse effluent at varied influent pHs (2.5-7.5). The Cr uptake at 60% saturation of the biomass was 6.3 mg/g at an optimum pH of 2.5. Desorption of the bound metal was partially achieved by washing the column biomass with a combined solution of 1% (w/v) formaldehyde and 1 M HNO3.","Column sorption of Cr(VI) from electroplating effluent using formaldehyde cross-linked Saccharomyces cerevisiae Abs: BIOSIS COPYRIGHT: BIOL ABS. Pellets of Saccharomyces cerevisiae, cross-linked by 13% (w/v) formaldehyde, were used in fixed-bed columns to remove Cr(VI) from electroplating rinse effluent at varied influent pHs (2.5-7.5). The Cr uptake at 60% saturation of the biomass was 6.3 mg/g at an optimum pH of 2.5. Desorption of the bound metal was partially achieved by washing the column biomass with a combined solution of 1% (w/v) formaldehyde and 1 M HNO3."
1516638,Wang and  Chirwa 1998,Simultaneous removal of Cr(VI) and phenol in chemostat culture of E. coli ATCC 33456 and P. putida DMP-1,"BIOSIS COPYRIGHT: BIOL ABS. A chemostat coculture consisting of a phenol-degrading organism, P. putida, and a Cr(VI)-reducing strain, E. coli ATCC 33456, was evaluated for its potential to simultaneously remove phenol and Cr(VI). Steady-state operating conditions were obtained with new complete removal of phenol and Cr(VI) under a range of influent concentration of phenol (233-2541 mg/l), influent Cr(VI) (1-10.3 mg/l), and liquid detention time (2-6.7 days).","Simultaneous removal of Cr(VI) and phenol in chemostat culture of E. coli ATCC 33456 and P. putida DMP-1 Abs: BIOSIS COPYRIGHT: BIOL ABS. A chemostat coculture consisting of a phenol-degrading organism, P. putida, and a Cr(VI)-reducing strain, E. coli ATCC 33456, was evaluated for its potential to simultaneously remove phenol and Cr(VI). Steady-state operating conditions were obtained with new complete removal of phenol and Cr(VI) under a range of influent concentration of phenol (233-2541 mg/l), influent Cr(VI) (1-10.3 mg/l), and liquid detention time (2-6.7 days)."
1516637,Zschiesche 1999,"Report on the International Symposium on Environment, Life Style, and Fertility. (Aarhus, Denmark; 7-10 December 1997) (European Union; Danish Medical Research Council; International Conference on Occupational Health Scientific Community)",Biosis copyright: biol abs. rrm meeting report human male female human occupational health lifestyle fertility male reproductivity pregnancy fecundity reproductive system male infertility female infertility menstrual cycle sperm hazards lifestyle factors occupational hazards reproductive system disease reproductive system disease/female reproductive system,"Report on the International Symposium on Environment, Life Style, and Fertility. (Aarhus, Denmark; 7-10 December 1997) (European Union; Danish Medical Research Council; International Conference on Occupational Health Scientific Community) Abs: Biosis copyright: biol abs. rrm meeting report human male female human occupational health lifestyle fertility male reproductivity pregnancy fecundity reproductive system male infertility female infertility menstrual cycle sperm hazards lifestyle factors occupational hazards reproductive system disease reproductive system disease/female reproductive system"
1516636,Yare 1975,The use of a specialized drilling and ground water sampling technique for delineation of hexavalent chromium contamination in an unconfined aquifer southern new-jersey coastal plain,Heep copyright: biol abs.,The use of a specialized drilling and ground water sampling technique for delineation of hexavalent chromium contamination in an unconfined aquifer southern new-jersey coastal plain Abs: Heep copyright: biol abs.
1516635,Yongue et al. 1979,Survival of Euglena gracilis exposed to sublethal temperature and hexavalent chromium,"HEEP COPYRIGHT: BIOL ABS. At room temperature ( 20ê C) the concentration of 1 mg/l of Cr, as CrO3, and a 3-h exposure were the conditions at which most E. gracilis survived. Euglena subjected to 31.5 0.5ê C for 1 h, then cooled to room temperature and treated with Cr, was as sensitive to 0.001 mg/l as to 10 mg/l. When simultaneously subjected to 31.5 | 0.5ê C and Cr, survival of Euglena was < 50% at concentrations down to 0.001 mg/l by the end of 3 h.","Survival of Euglena gracilis exposed to sublethal temperature and hexavalent chromium Abs: HEEP COPYRIGHT: BIOL ABS. At room temperature ( 20ê C) the concentration of 1 mg/l of Cr, as CrO3, and a 3-h exposure were the conditions at which most E. gracilis survived. Euglena subjected to 31.5 0.5ê C for 1 h, then cooled to room temperature and treated with Cr, was as sensitive to 0.001 mg/l as to 10 mg/l. When simultaneously subjected to 31.5 | 0.5ê C and Cr, survival of Euglena was < 50% at concentrations down to 0.001 mg/l by the end of 3 h."
1516634,Wei et al. 1982,Spectrophotometric determination of microgram amounts of chromium(VI) and total chromium in wastewater,HEEP COPYRIGHT: BIOL ABS. A spectrophotometric method was developed for the determination of Cr in wastewater with 5-Br-PADAP (2-(5-bromo-2-pyridylazo)-5-diethylaminophenol). Cr (III) formed a blue-purple complex at pH 4.7 upon heating. The color was stable and highly sensitive for Cr. At 600 nm it obeyed Beer's law in the concentration range 0-15 mug Cr(III)/25 ml. The sensitivity and molar absorptivity of the reaction were 0.00065 mug Cr(III)/cm2 and 7.93e continuous variation and molar ratio methods indicated that Cr formed a 1:2 complex with the ligand.,Spectrophotometric determination of microgram amounts of chromium(VI) and total chromium in wastewater Abs: HEEP COPYRIGHT: BIOL ABS. A spectrophotometric method was developed for the determination of Cr in wastewater with 5-Br-PADAP (2-(5-bromo-2-pyridylazo)-5-diethylaminophenol). Cr (III) formed a blue-purple complex at pH 4.7 upon heating. The color was stable and highly sensitive for Cr. At 600 nm it obeyed Beer's law in the concentration range 0-15 mug Cr(III)/25 ml. The sensitivity and molar absorptivity of the reaction were 0.00065 mug Cr(III)/cm2 and 7.93e continuous variation and molar ratio methods indicated that Cr formed a 1:2 complex with the ligand.
1516632,Zey and  Liss 1983,"Health hazard evaluation report no. HETA-82-173-1325, Westinghouse Electric Corporation, St. Louis, Missouri","Environmental and breathing zone samples were analyzed for xylene (1330207) hexavalent-chromium (18540299) (Cr-VI), metallic chromium (7440473) (Cr), lead (7439921) (Pb), and zinc (7440666) (Zn) at the Westinghouse Electric Corporation (SIC-3613), St. Louis, Missouri in May 1983. The evaluation was requested because of employee concern about exposure to hazardous chemicals on the paint line. Airborne xylene concentrations ranged from 0.9 to 14 milligrams per cubic meter (mg/m3). The OSHA standard is 435mg/m3. The air concentration of the metals was: Cr, 0.077 to 0.93mg/m3; and Zn, 0.333 to 0.386mg/m3; Pb was not present in detectable amounts. Airborne Cr-VI concentrations ranged up to 0.011mg/m3. The OSHA standard for Cr-VI is 0.1mg/m3 and the American Conference of Governmental Industrial Hygienists standard for Zn is 5.0mg/m3. Twelve exposed and 11 nonexposed employees were interviewed and urine and serum samples were collected. Urinary methylhippuric-acid (2198643) concentrations were low, indicating low exposure to xylene. Serum samples showed no significant difference in liver function abnormalities between the two groups. The authors conclude a health hazard did not exist on the paint line. They recommend that a program of worker education be instituted and that respirators in the paint shop be carefully maintained.","Health hazard evaluation report no. HETA-82-173-1325, Westinghouse Electric Corporation, St. Louis, Missouri Abs: Environmental and breathing zone samples were analyzed for xylene (1330207) hexavalent-chromium (18540299) (Cr-VI), metallic chromium (7440473) (Cr), lead (7439921) (Pb), and zinc (7440666) (Zn) at the Westinghouse Electric Corporation (SIC-3613), St. Louis, Missouri in May 1983. The evaluation was requested because of employee concern about exposure to hazardous chemicals on the paint line. Airborne xylene concentrations ranged from 0.9 to 14 milligrams per cubic meter (mg/m3). The OSHA standard is 435mg/m3. The air concentration of the metals was: Cr, 0.077 to 0.93mg/m3; and Zn, 0.333 to 0.386mg/m3; Pb was not present in detectable amounts. Airborne Cr-VI concentrations ranged up to 0.011mg/m3. The OSHA standard for Cr-VI is 0.1mg/m3 and the American Conference of Governmental Industrial Hygienists standard for Zn is 5.0mg/m3. Twelve exposed and 11 nonexposed employees were interviewed and urine and serum samples were collected. Urinary methylhippuric-acid (2198643) concentrations were low, indicating low exposure to xylene. Serum samples showed no significant difference in liver function abnormalities between the two groups. The authors conclude a health hazard did not exist on the paint line. They recommend that a program of worker education be instituted and that respirators in the paint shop be carefully maintained."
1516631,Xinju and  Yungai 1982,Research On The New Clean-up Process Of Chromium Plating,"A vapor spray technique for chromium (18540299) plating operations was evaluated. Water and air samples were analyzed, and chromium tank evaporation and drag out quantities were determined. Evaporation of the plating substrate was related to the solution temperature, area of evaporation, daily workload, and ventilation. Drag out quantities for holed clamp rod and sliding cubes were 0.8 and 1.3, respectively. Evaporation from plating baths averaged 11 liters per day. Spraying efficiency and spray water consumption were calculated. By using vapor spraying, the average water consumption per rack was 0.304 liter. Based on a workload of 30 racks, consumption was 18.12 liters, and total amount reclaimed was 9.12 liters. The authors conclude that the new technique combines nebulization and countercurrent rinsing while applying vapor spray on work drag out. Efficiency is about 96 percent, and the process saves on water consumption. The technique uses simple equipment, a closely knit structure, and is economical. Production flow is rapid and operation is simple. (Chinese)","Research On The New Clean-up Process Of Chromium Plating Abs: A vapor spray technique for chromium (18540299) plating operations was evaluated. Water and air samples were analyzed, and chromium tank evaporation and drag out quantities were determined. Evaporation of the plating substrate was related to the solution temperature, area of evaporation, daily workload, and ventilation. Drag out quantities for holed clamp rod and sliding cubes were 0.8 and 1.3, respectively. Evaporation from plating baths averaged 11 liters per day. Spraying efficiency and spray water consumption were calculated. By using vapor spraying, the average water consumption per rack was 0.304 liter. Based on a workload of 30 racks, consumption was 18.12 liters, and total amount reclaimed was 9.12 liters. The authors conclude that the new technique combines nebulization and countercurrent rinsing while applying vapor spray on work drag out. Efficiency is about 96 percent, and the process saves on water consumption. The technique uses simple equipment, a closely knit structure, and is economical. Production flow is rapid and operation is simple. (Chinese)"
1516630,Zey and  Aw 1984,"Health hazard evaluation report no. HETA-82-025-1413, American Transportation Corporation, Conway, Arkansas","Exposures to lead (7439910), hexavalent-chromium (18540299), total particulates, and organic solvents were investigated in February 1982 at American Transportation Corporation (SIC-3711), Conway, Arkansas. Evaluation was requested by the United Auto Workers, Local 1762, on behalf of workers complaining of dermatitis and eye, nose, throat, and respiratory irritations. Area and personal air samples were collected. Medical questionnaires, blood lead tests, and liver and kidney function tests were completed by 57 exposed workers. Four of five samples for hexavalent-chromium exceeded the OSHA limit of 0.1 milligram per cubic meter (mg/m3); four of eight lead samples exceeded the 0.05mg/m3 OSHA standard. For total particulates, two of eight samples exceeded the OSHA limit of 15mg/m3. Exposures to organic solvents were all within acceptable limits. Deficiencies were noted in the respiratory and hearing protection programs, and in the paint booth ventilation system. Numerous safety hazards were also found: smoking around solvents, open solvent containers, and poor housekeeping. Dermatitis incidence was greater among the exposed workers, and there was evidence of toluene (108883) absorption. Blood lead values were normal. The authors conclude that potential hazards exist from lead and hexavalent-chromium; general health and safety hazards are also present. They recommend improved work and hygiene practices.","Health hazard evaluation report no. HETA-82-025-1413, American Transportation Corporation, Conway, Arkansas Abs: Exposures to lead (7439910), hexavalent-chromium (18540299), total particulates, and organic solvents were investigated in February 1982 at American Transportation Corporation (SIC-3711), Conway, Arkansas. Evaluation was requested by the United Auto Workers, Local 1762, on behalf of workers complaining of dermatitis and eye, nose, throat, and respiratory irritations. Area and personal air samples were collected. Medical questionnaires, blood lead tests, and liver and kidney function tests were completed by 57 exposed workers. Four of five samples for hexavalent-chromium exceeded the OSHA limit of 0.1 milligram per cubic meter (mg/m3); four of eight lead samples exceeded the 0.05mg/m3 OSHA standard. For total particulates, two of eight samples exceeded the OSHA limit of 15mg/m3. Exposures to organic solvents were all within acceptable limits. Deficiencies were noted in the respiratory and hearing protection programs, and in the paint booth ventilation system. Numerous safety hazards were also found: smoking around solvents, open solvent containers, and poor housekeeping. Dermatitis incidence was greater among the exposed workers, and there was evidence of toluene (108883) absorption. Blood lead values were normal. The authors conclude that potential hazards exist from lead and hexavalent-chromium; general health and safety hazards are also present. They recommend improved work and hygiene practices."
1516628,Zaebst and  Herrick 1985,"Industrial Hygiene Survey Report Of Millstone Nuclear Power Station No. 3 Construction Site, Waterford, Connecticut, Report No. IWS-74-69","Personal and area air samples were analyzed for total dust, organic solvent vapors, and metals during spray, brush, and roller painting and paint removal operations (SIC-1629) at Millstone Nuclear Power Station Number 3 construction site, Waterford, Connecticut, March 1981. Solvent exposures were generally well below their relevant standards. Total dust exposures during paint removal ranged up to 1,000 milligrams per cubic meter (mg/m3) in the containment building. The OSHA standard for total dust is 15mg/m3. Exposures to lead (7439921) dusts exceeded the OSHA standard of 0.05mg/m3 in the turbine, auxiliary, and containment buildings. Chromium (7440473) exposures were generally below the OSHA standard of 1mg/m3, except for 2.4mg/m3 in a personal sample taken during paint removal in the containment building. Very few engineering controls other than 3M single use respirators were observed. The authors note that the chromium exposure data is difficult to interpret as the form of the chromium is not known. If the chromium existed as hexavalent chromium, exposure was excessive. The authors conclude that in view of the measured exposures to total dust, lead, and chromium, engineering controls and respiratory protection are inadequate. Recommendations include implementing better controls and respiratory protection.","Industrial Hygiene Survey Report Of Millstone Nuclear Power Station No. 3 Construction Site, Waterford, Connecticut, Report No. IWS-74-69 Abs: Personal and area air samples were analyzed for total dust, organic solvent vapors, and metals during spray, brush, and roller painting and paint removal operations (SIC-1629) at Millstone Nuclear Power Station Number 3 construction site, Waterford, Connecticut, March 1981. Solvent exposures were generally well below their relevant standards. Total dust exposures during paint removal ranged up to 1,000 milligrams per cubic meter (mg/m3) in the containment building. The OSHA standard for total dust is 15mg/m3. Exposures to lead (7439921) dusts exceeded the OSHA standard of 0.05mg/m3 in the turbine, auxiliary, and containment buildings. Chromium (7440473) exposures were generally below the OSHA standard of 1mg/m3, except for 2.4mg/m3 in a personal sample taken during paint removal in the containment building. Very few engineering controls other than 3M single use respirators were observed. The authors note that the chromium exposure data is difficult to interpret as the form of the chromium is not known. If the chromium existed as hexavalent chromium, exposure was excessive. The authors conclude that in view of the measured exposures to total dust, lead, and chromium, engineering controls and respiratory protection are inadequate. Recommendations include implementing better controls and respiratory protection."
1516627,Zey et al. 1827,"Health Hazard Evaluation Report No. HETA-85-159-1827, Blackman Uhler Chemical Company (Synalloy Corporation), Spartanburg, South Carolin","In response to a confidential request, evaluation was made of bladder cancer incidence among workers at Blackman Uhler Chemical Company, Spartanburg, South Carolina. Short term air samples were collected for dimethyl-formamide (68122), ortho-dianisidine (119904), and chromium(VI) (18540299). Five of six samples showed no detectable levels of these compounds; the sixth showed a level of dimethyl-formamide well below OSHA permissible exposure limits. Deficiencies were noted in chemical handling procedures, work practices, engineering controls, and employee training and education regarding safety practices. There was a medical screening program for bladder cancer at the facility, but 689 of the 919 current and former employees had not participated. One case had been identified as of April 1985. It is suggested that there may be undetected cases of bladder cancer. It is recommended that better education of employees be undertaken concerning chemicals with which they work; that work practices be modified; that respiratory protection be improved with emphasis on selection, cleaning and maintenance, fit testing, and proper storage of protective equipment; that emergency showers and eye baths be inspected regularly; that labels be properly placed on tanks; that the screening program for medical problems continue to be available to all current and former workers; and that special medical evaluation be performed for any employee with urinary tract symptoms, microhematuria, or nonnegative cytology.","Health Hazard Evaluation Report No. HETA-85-159-1827, Blackman Uhler Chemical Company (Synalloy Corporation), Spartanburg, South Carolin Abs: In response to a confidential request, evaluation was made of bladder cancer incidence among workers at Blackman Uhler Chemical Company, Spartanburg, South Carolina. Short term air samples were collected for dimethyl-formamide (68122), ortho-dianisidine (119904), and chromium(VI) (18540299). Five of six samples showed no detectable levels of these compounds; the sixth showed a level of dimethyl-formamide well below OSHA permissible exposure limits. Deficiencies were noted in chemical handling procedures, work practices, engineering controls, and employee training and education regarding safety practices. There was a medical screening program for bladder cancer at the facility, but 689 of the 919 current and former employees had not participated. One case had been identified as of April 1985. It is suggested that there may be undetected cases of bladder cancer. It is recommended that better education of employees be undertaken concerning chemicals with which they work; that work practices be modified; that respiratory protection be improved with emphasis on selection, cleaning and maintenance, fit testing, and proper storage of protective equipment; that emergency showers and eye baths be inspected regularly; that labels be properly placed on tanks; that the screening program for medical problems continue to be available to all current and former workers; and that special medical evaluation be performed for any employee with urinary tract symptoms, microhematuria, or nonnegative cytology."
1516626,Walsh and  O'Halloran 1996,Chromium speciation in tannery effluent-II. Speciation in the effluent and in a receiving estuary,"BIOSIS COPYRIGHT: BIOL ABS. The forms and transformations of chromium were characterized in the effluent of an Irish tannery before and after discharge into an estuary. The three primary effluent streams in the tannery were studied, i.e. the chrome and sulphide streams and the final composite effluent. Chromium was fully speciated in the final effluent, the discharge plume, and in the estuary outside discharge periods. The partitioning of chromium was also studied in the sediments, and transformations due to the remobilisation and oxidation of Cr(III) were followed. These data were compared to a reference site. Mixing of the chrome and sulphide streams resulted in the binding of Cr(III) to organic ligands, notably proteins. The speciation of chromium in the final effluent was dominated by Cr(III) particulates with a mean concentration of 72.4 mg Cr l-1. Some 80-90% of these particulates were inorganic while 10-20% were bound to organic ligands. Dissolved concentrations averaged 3.6 mg l-1 at pH 10","Chromium speciation in tannery effluent-II. Speciation in the effluent and in a receiving estuary Abs: BIOSIS COPYRIGHT: BIOL ABS. The forms and transformations of chromium were characterized in the effluent of an Irish tannery before and after discharge into an estuary. The three primary effluent streams in the tannery were studied, i.e. the chrome and sulphide streams and the final composite effluent. Chromium was fully speciated in the final effluent, the discharge plume, and in the estuary outside discharge periods. The partitioning of chromium was also studied in the sediments, and transformations due to the remobilisation and oxidation of Cr(III) were followed. These data were compared to a reference site. Mixing of the chrome and sulphide streams resulted in the binding of Cr(III) to organic ligands, notably proteins. The speciation of chromium in the final effluent was dominated by Cr(III) particulates with a mean concentration of 72.4 mg Cr l-1. Some 80-90% of these particulates were inorganic while 10-20% were bound to organic ligands. Dissolved concentrations averaged 3.6 mg l-1 at pH 10"
1516625,Walsh and  O'Halloran 1996,Chromium speciation in tannery effluent-I. An assessment of techniques and the role of organic Cr(III) complexes,"BIOSIS COPYRIGHT: BIOL ABS. Three methods of chromium speciation were assessed in relation to possible interferences from Cr(III)-organic complexes. They were, namely: 1,5-diphenyl-carbazide (DPC) spectrophotometry, organic extraction with methyl isobutyl ketone (MIBK) and co-precipitation with iron and bismuth salts. Initially, a number of organic ligands, i.e. proteins, amino acids and organic acids were reacted with Cr(III) and only those complexes with solubility levels above that of ionic Cr(III) were assessed further. The spectrophotometric method was found to suffer minor interferences which were attributable to a non-specific turbidity effect. In comparison, two methods of MIBK extraction were found to suffer severe interferences with Cr(III)-protein complexes. Also, co-precipitation with iron salts resulted in high levels of contamination by Cr(III)-organic complexes in the ionic chromium fractions. Due to the poor solubility of bismuth salts, this method was discarded. The results demons","Chromium speciation in tannery effluent-I. An assessment of techniques and the role of organic Cr(III) complexes Abs: BIOSIS COPYRIGHT: BIOL ABS. Three methods of chromium speciation were assessed in relation to possible interferences from Cr(III)-organic complexes. They were, namely: 1,5-diphenyl-carbazide (DPC) spectrophotometry, organic extraction with methyl isobutyl ketone (MIBK) and co-precipitation with iron and bismuth salts. Initially, a number of organic ligands, i.e. proteins, amino acids and organic acids were reacted with Cr(III) and only those complexes with solubility levels above that of ionic Cr(III) were assessed further. The spectrophotometric method was found to suffer minor interferences which were attributable to a non-specific turbidity effect. In comparison, two methods of MIBK extraction were found to suffer severe interferences with Cr(III)-protein complexes. Also, co-precipitation with iron salts resulted in high levels of contamination by Cr(III)-organic complexes in the ionic chromium fractions. Due to the poor solubility of bismuth salts, this method was discarded. The results demons"
1516624,Wallen 1990,The toxicity of chromium (VI) to photosynthesis of the phytoplankton assemblage of Lake Erie (Canada) and the diatom Fragilaria crotonensis Kitton,"BIOSIS COPYRIGHT: BIOL ABS. Photosynthesis of natural phytoplankton assemblages and the diatom Fragilaria crotonensis Kitton, from Lake Erie, was measured in the presence of chromium (VI) from 0 to 2.0 muM. All chromium concentrations tested inhibited the photosynthetic capacity (Pmax) of the photosynthesis-irradiance (P-I) relationship of F. crotonensis, with inhibition being greatest at 2.0 muM Cr(VI), the highest concentration tested. Pmax values of the phytoplankton assemblage were also reduced, but the effects were less severe in that 2.0 muM Cr(VI) reduced Pmax to 37.5% of the control compared with 5.9% for F. crotonensis. Changes in the slope (alpha) of the P-I curve of F. crotonensis indicated inhibition at all concentrations except 0.5 muM Cr(VI), inhibition being greatest at 2.0 muM Cr(VI), 12.4% of the control. However, for the phytoplankton assemblage, inhibition was observed only at a concentration of 2.0 muM, reducing alpha from 3.2-1 photons m-2 s-2, 56% of the control.","The toxicity of chromium (VI) to photosynthesis of the phytoplankton assemblage of Lake Erie (Canada) and the diatom Fragilaria crotonensis Kitton Abs: BIOSIS COPYRIGHT: BIOL ABS. Photosynthesis of natural phytoplankton assemblages and the diatom Fragilaria crotonensis Kitton, from Lake Erie, was measured in the presence of chromium (VI) from 0 to 2.0 muM. All chromium concentrations tested inhibited the photosynthetic capacity (Pmax) of the photosynthesis-irradiance (P-I) relationship of F. crotonensis, with inhibition being greatest at 2.0 muM Cr(VI), the highest concentration tested. Pmax values of the phytoplankton assemblage were also reduced, but the effects were less severe in that 2.0 muM Cr(VI) reduced Pmax to 37.5% of the control compared with 5.9% for F. crotonensis. Changes in the slope (alpha) of the P-I curve of F. crotonensis indicated inhibition at all concentrations except 0.5 muM Cr(VI), inhibition being greatest at 2.0 muM Cr(VI), 12.4% of the control. However, for the phytoplankton assemblage, inhibition was observed only at a concentration of 2.0 muM, reducing alpha from 3.2-1 photons m-2 s-2, 56% of the control."
1516623,Wall and  Stratton 1994,The effects of chromium on the growth and activity of a pentachlorophenol-degrading bacterium,"BIOSIS COPYRIGHT: BIOL ABS. The effects of chromium (or chromate, as supplied by CrO3) on a pentachlorophenol-degrading Flavobacterium sp. (ATCC 53874) were examined in a liquid bacterial growth medium. Cr6+ concentrations \ 5.0 mug mL-1 caused the complete inhibition of bacterial growth. The EC25, EC50, and EC75 calculated after 96 h of incubation were 0.44, 1.44, and 3.82 mug mL-1, respectively. Cr6+ caused an irreversible reduction in total cell yield during the 21-day incubation. Cr6+ also elicited an increase in the lag time recorded before there was measurable pentachlorophenol (PCP) degradation by this bacterium. There was also an increase in the overall time required for complete degradation of PCP to nondetectable levels. A similar response was noted with all PCP concentrations examined from 10 to 100 mug mL-1. However, a more pronounced response occurred at the lower PCP concentrations. The significance of these data relative to the in situ use of PCP-degrading bacteria for site bioreme","The effects of chromium on the growth and activity of a pentachlorophenol-degrading bacterium Abs: BIOSIS COPYRIGHT: BIOL ABS. The effects of chromium (or chromate, as supplied by CrO3) on a pentachlorophenol-degrading Flavobacterium sp. (ATCC 53874) were examined in a liquid bacterial growth medium. Cr6+ concentrations \ 5.0 mug mL-1 caused the complete inhibition of bacterial growth. The EC25, EC50, and EC75 calculated after 96 h of incubation were 0.44, 1.44, and 3.82 mug mL-1, respectively. Cr6+ caused an irreversible reduction in total cell yield during the 21-day incubation. Cr6+ also elicited an increase in the lag time recorded before there was measurable pentachlorophenol (PCP) degradation by this bacterium. There was also an increase in the overall time required for complete degradation of PCP to nondetectable levels. A similar response was noted with all PCP concentrations examined from 10 to 100 mug mL-1. However, a more pronounced response occurred at the lower PCP concentrations. The significance of these data relative to the in situ use of PCP-degrading bacteria for site bioreme"
1516622,Walker et al. 1997,In-situ reduction of hexavalent chromium in groundwater and surface soil using acidified ferrous sulfate,Biosis copyright: biol abs. rrm meeting abstract hexavalent chromium in-situ reduction pollutant acidified ferrous sulfate reducing agent contaminated groundwater contaminated surface soil pollution,In-situ reduction of hexavalent chromium in groundwater and surface soil using acidified ferrous sulfate Abs: Biosis copyright: biol abs. rrm meeting abstract hexavalent chromium in-situ reduction pollutant acidified ferrous sulfate reducing agent contaminated groundwater contaminated surface soil pollution
1516621,Wai et al. 1987,A 2-step extraction method for differentiating chromium species in water,Biosis copyright: biol abs. rrm human hexavalent chromium toxicity water pollution natural water systems,A 2-step extraction method for differentiating chromium species in water Abs: Biosis copyright: biol abs. rrm human hexavalent chromium toxicity water pollution natural water systems
1516620,Vuceta et al. 1979,Bench-scale testing for residual waste treatment,"HEEP COPYRIGHT: BIOL ABS. The most effective technologies for centralized treatment of various industrial residual wastes generated in Ventura County (California, USA) were determined by laboratory experiments. Steps required for a successful treatment of metallic wastes include cyanide and cyanate oxidation, Cr (VI) reduction, hydroxide and sulfide precipitation, coagulation and flocculation, and filtration. Ion exchange and C sorption are not usually required. Coagulation and flocculation of nonmetallic toxic wastes, followed by filtration and C sorption, is more effective in the removal of toxic nonmetallic substances from wastewaters than foam fractionation coupled with carbon sorption. A batch mode of operation is superior to continuous flow.","Bench-scale testing for residual waste treatment Abs: HEEP COPYRIGHT: BIOL ABS. The most effective technologies for centralized treatment of various industrial residual wastes generated in Ventura County (California, USA) were determined by laboratory experiments. Steps required for a successful treatment of metallic wastes include cyanide and cyanate oxidation, Cr (VI) reduction, hydroxide and sulfide precipitation, coagulation and flocculation, and filtration. Ion exchange and C sorption are not usually required. Coagulation and flocculation of nonmetallic toxic wastes, followed by filtration and C sorption, is more effective in the removal of toxic nonmetallic substances from wastewaters than foam fractionation coupled with carbon sorption. A batch mode of operation is superior to continuous flow."
1516619,Vincze et al. 1994,Investigation of chromium (VI) tolerant bacteria,"BIOSIS COPYRIGHT: BIOL ABS. Pseudomonas strains were isolated from a heavy metal contaminated sludge. Some of the strains grew on chromium (VI) containing medium, and others were inhibited in their growth. Cells were able to remove chromium from the medium. This ability was independent of the rate of their growth. The concentration of chromium (VI) of the media decreased with 15-20 ppm in presence of 109 cells. The chromium (VI) was converted into a reduced form of chromium by bacteria. The reduced form of chromium was bound in the cell well. The bound form of chromium could be recovered more or less with different chemicals. The best percentages of recovery were achieved with NaOH solution.","Investigation of chromium (VI) tolerant bacteria Abs: BIOSIS COPYRIGHT: BIOL ABS. Pseudomonas strains were isolated from a heavy metal contaminated sludge. Some of the strains grew on chromium (VI) containing medium, and others were inhibited in their growth. Cells were able to remove chromium from the medium. This ability was independent of the rate of their growth. The concentration of chromium (VI) of the media decreased with 15-20 ppm in presence of 109 cells. The chromium (VI) was converted into a reduced form of chromium by bacteria. The reduced form of chromium was bound in the cell well. The bound form of chromium could be recovered more or less with different chemicals. The best percentages of recovery were achieved with NaOH solution."
1516618,Villalobos-Penalosa et al. 1987,A study of the factors that influence the interference of iron-iii in the colorimetric analysis of chromium-vi in polluted waters,Biosis copyright: biol abs. rrm contact time ph temperature,A study of the factors that influence the interference of iron-iii in the colorimetric analysis of chromium-vi in polluted waters Abs: Biosis copyright: biol abs. rrm contact time ph temperature
1516617,Villaescusa et al. 1997,Chromium (VI) toxicity to luminescent bacteria,"BIOSIS COPYRIGHT: BIOL ABS. The toxicity of chromium(VI) to luminescent bacteria was determined using the Microtox bioassay. The aim of this study was to assess the influence of pH on the toxicity of Cr(VI) samples because its speciation depends on this parameter. A Microtox test basic protocol, modified to assure the same pH in all the cuvettes, was used to determine the toxicity of the Cr(VI) compounds. In the range studied, 4.6 to 9.3, the observed EC50 values increased with the pH (31-1,184 mg Cr(VI)). These toxicity results were related to the percentage of the different Cr(VI) species. Hydrogenchromate anion was found to be the most toxic species. In general, only slight differences in toxicity were found when the Microtox test basic protocol was used. Nevertheless, when 20.4% (w/v) sucrose was used as an alternative medium to 2% (w/v) NaCl, the results obtained could not be compared because the sensitivity of the bacteria in this medium was found to be different. The influence of an exposu","Chromium (VI) toxicity to luminescent bacteria Abs: BIOSIS COPYRIGHT: BIOL ABS. The toxicity of chromium(VI) to luminescent bacteria was determined using the Microtox bioassay. The aim of this study was to assess the influence of pH on the toxicity of Cr(VI) samples because its speciation depends on this parameter. A Microtox test basic protocol, modified to assure the same pH in all the cuvettes, was used to determine the toxicity of the Cr(VI) compounds. In the range studied, 4.6 to 9.3, the observed EC50 values increased with the pH (31-1,184 mg Cr(VI)). These toxicity results were related to the percentage of the different Cr(VI) species. Hydrogenchromate anion was found to be the most toxic species. In general, only slight differences in toxicity were found when the Microtox test basic protocol was used. Nevertheless, when 20.4% (w/v) sucrose was used as an alternative medium to 2% (w/v) NaCl, the results obtained could not be compared because the sensitivity of the bacteria in this medium was found to be different. The influence of an exposu"
1516616,Vidal et al. 1992,Speciation of chromium(VI) CHROMIUM(III)0(III) by electrothermal atomisation AAS after electrodeposition on a L'vov platform,"BIOSIS COPYRIGHT: BIOL ABS. The pyrolysed graphite L'vov platform of a tube furnace is considered as an electrode for the electrodeposition and speciation of chromium by electrothermal atomisation atomic absorption spectrometry (ETA-AAS). Firstly, a preliminary study of the Cr(VI)r(III) voltammetric behavior at pH 4.70 on a glassy-carbon electrode is carried out. Secondly, the L'vov platform is used as a cathodic macro-electrode for the selective preconcentration of Cr(VI)/Cr(III) on a mercury film. Speciation of Cr(VI)/Cr(III) is carried out on the basis of the electrolysis potential (Ee): at pH 4.70 and Ee = 0.30 V, only Cr(VI) is reduced to Cr(III) and accumulated as Cr(OH)3 by adsorption on a mercury film; at Ee = -1.80 V both Cr(VI) and Cr(III) are accumulated forming an amalgam with added mercury(II) ions. Once the film has been formed, the platform is transferred to a graphite tube to atomise the element. The reliability of the method was tested for the speciation of chromium in natural wate","Speciation of chromium(VI) CHROMIUM(III)0(III) by electrothermal atomisation AAS after electrodeposition on a L'vov platform Abs: BIOSIS COPYRIGHT: BIOL ABS. The pyrolysed graphite L'vov platform of a tube furnace is considered as an electrode for the electrodeposition and speciation of chromium by electrothermal atomisation atomic absorption spectrometry (ETA-AAS). Firstly, a preliminary study of the Cr(VI)r(III) voltammetric behavior at pH 4.70 on a glassy-carbon electrode is carried out. Secondly, the L'vov platform is used as a cathodic macro-electrode for the selective preconcentration of Cr(VI)/Cr(III) on a mercury film. Speciation of Cr(VI)/Cr(III) is carried out on the basis of the electrolysis potential (Ee): at pH 4.70 and Ee = 0.30 V, only Cr(VI) is reduced to Cr(III) and accumulated as Cr(OH)3 by adsorption on a mercury film; at Ee = -1.80 V both Cr(VI) and Cr(III) are accumulated forming an amalgam with added mercury(II) ions. Once the film has been formed, the platform is transferred to a graphite tube to atomise the element. The reliability of the method was tested for the speciation of chromium in natural wate"
1516614,Verriopoulos et al. 1989,"Studies on the impact of chromium on the marine gastropod Monodonta turbinata (toxicity, bioaccumulation, acclimation)","BIOSIS COPYRIGHT: BIOL ABS. In this study we examined some aspects (L C 50 48h, LT 50 and bioaccumulation) of the impact of chromnium (Cr+6) to the gastropod Monodonta turbinata. For the experiments we used animals whch had been exposed for different periods to 1 ppm of Cr (acclimated) and subsequently placed in clean sea water (detoxified). For non-acclimated gastropods the LC 50 is 51.9 ppm of Cr and for the acclimated ones it is 72.77 ppm of Cr. A statistically significant relationship was observed between the LT 50, acclimation and detoxification time. The observed concentrations of Cr in Monodonta tissues are related to exposure time, pollutant concentration and detoxification time. Finally, the present results strongly suggest that the acquired tolerance doesn't become a permanent characteristic of animals.","Studies on the impact of chromium on the marine gastropod Monodonta turbinata (toxicity, bioaccumulation, acclimation) Abs: BIOSIS COPYRIGHT: BIOL ABS. In this study we examined some aspects (L C 50 48h, LT 50 and bioaccumulation) of the impact of chromnium (Cr+6) to the gastropod Monodonta turbinata. For the experiments we used animals whch had been exposed for different periods to 1 ppm of Cr (acclimated) and subsequently placed in clean sea water (detoxified). For non-acclimated gastropods the LC 50 is 51.9 ppm of Cr and for the acclimated ones it is 72.77 ppm of Cr. A statistically significant relationship was observed between the LT 50, acclimation and detoxification time. The observed concentrations of Cr in Monodonta tissues are related to exposure time, pollutant concentration and detoxification time. Finally, the present results strongly suggest that the acquired tolerance doesn't become a permanent characteristic of animals."
1516613,Venugopal and  Reddy 1992,Effect of trivalent and hexavalent chromium on renal and hepatic tissue glycogen metabolism of a fresh water teleost Anabas scandens,"BIOSIS COPYRIGHT: BIOL ABS. The in vivo toxic impact of chromium in its two forms (trivalent and hexavalent) on glycogen metabolism in the liver and kidney of a fresh water teleost Anabas scandens was studied. In a sub-chronic exposure of 30 days, depletion of glycogen and glucose reserves reflected in the activity patterns of glycogen phosphorylases 'a and ab'. While both forms of chromium induced alterations in enzyme activities and metabolite levels in the two tissues, Cr+6 exerted greater effects in the kidney.","Effect of trivalent and hexavalent chromium on renal and hepatic tissue glycogen metabolism of a fresh water teleost Anabas scandens Abs: BIOSIS COPYRIGHT: BIOL ABS. The in vivo toxic impact of chromium in its two forms (trivalent and hexavalent) on glycogen metabolism in the liver and kidney of a fresh water teleost Anabas scandens was studied. In a sub-chronic exposure of 30 days, depletion of glycogen and glucose reserves reflected in the activity patterns of glycogen phosphorylases 'a and ab'. While both forms of chromium induced alterations in enzyme activities and metabolite levels in the two tissues, Cr+6 exerted greater effects in the kidney."
1516612,Velinova and  Koumanova 1995,Statistical modelling of wastewater quality: The case of micro-electronics industry,"BIOSIS COPYRIGHT: BIOL ABS. Using a passive experiment, wastewaters from a micro-electronics industry were subjected to experimental evaluation and models for effluent quality prediction were generated. The parameters total solids (TS105) and concentration of Cr(VI) were used as dependent variables. Taking into account both system and experiment particularities, a detailed statistical procedure for model formulation, calibration and verification has been applied. Although the equations thus obtained are specific for the studied system, the procedure used for their development could be considered as applicable for chemometrics purposes.","Statistical modelling of wastewater quality: The case of micro-electronics industry Abs: BIOSIS COPYRIGHT: BIOL ABS. Using a passive experiment, wastewaters from a micro-electronics industry were subjected to experimental evaluation and models for effluent quality prediction were generated. The parameters total solids (TS105) and concentration of Cr(VI) were used as dependent variables. Taking into account both system and experiment particularities, a detailed statistical procedure for model formulation, calibration and verification has been applied. Although the equations thus obtained are specific for the studied system, the procedure used for their development could be considered as applicable for chemometrics purposes."
1516610,Vankova et al. 1997,Toxicity of substances to activated sludge: Course of inhibition curves,"BIOSIS COPYRIGHT: BIOL ABS. A method is described for determining the course of inhibition curves substantiating the influence of some inorganic (Cr (VI)) and organic substances (phenol, synthetic tanning agents) on respiratory activity of heterogeneous biomass (activated sludge). Presented results prove that calculated inhibition curves have the course of a normal distribution function.","Toxicity of substances to activated sludge: Course of inhibition curves Abs: BIOSIS COPYRIGHT: BIOL ABS. A method is described for determining the course of inhibition curves substantiating the influence of some inorganic (Cr (VI)) and organic substances (phenol, synthetic tanning agents) on respiratory activity of heterogeneous biomass (activated sludge). Presented results prove that calculated inhibition curves have the course of a normal distribution function."
1516609,Vandenbalck and  Patriarche 1987,Electrochemical micro-determinations of thallium-i and chromium-vi ions using dpasv and dp polarography,Biosis copyright: biol abs. rrm human heavy metal toxicity mercury film edta differential pulse anodic stripping voltammetry urine saliva rain water,Electrochemical micro-determinations of thallium-i and chromium-vi ions using dpasv and dp polarography Abs: Biosis copyright: biol abs. rrm human heavy metal toxicity mercury film edta differential pulse anodic stripping voltammetry urine saliva rain water
1516608,Van Der Wal 1986,"Further Studies on the Exposure of Welders to Fumes, Chromium, Nickel and Gases in Dutch Industries: Plasma Welding and Cutting of Stainless Steel","Two breathing zone air samples were collected per shift from plasma welding and cutting workers in six industries. Total welding fume, chromium (7440473), and nickel (7440020) concentrations were determined. The standard for welding fumes in Holland is 5mg/m3, and was exceeded in plasma cutting of stainless steel when local exhaust ventilation was not present. Fume concentration was below standard levels when ventilation was present or when the cutting was done under water. Only two industries gave detectable amounts of hexavalent chromium (18540299) in concentrations from 20 to 40 micrograms/cubic meter (microg/m3). Total chromium concentrations were found up to 440microg/m3, which was below the Dutch standard of 500microg/m3. Concentrations of nickel were detected up to 260microg/m3, even when an alloy with 30 to 35 percent nickel was cut. Nitrogen-dioxide (10102440) levels were below the standard of 9mg/m3, with plasma welding giving readings up to 0.2mg/m3 and plasma cutting up to 1.1mg/m3. A peak concentration of 7mg/m3 was noted in one industry during plasma cutting of stainless steel. Nitrous-oxide (10024972) concentrations were well below the standards. Microplasma welding air samples did give indication of some high ozone (10028156) concentrations, and this situation was improved through the placing of a glass screen on the table between the torch and the worker's face. This also enabled the worker to be protected against ultraviolet radiation.","Further Studies on the Exposure of Welders to Fumes, Chromium, Nickel and Gases in Dutch Industries: Plasma Welding and Cutting of Stainless Steel Abs: Two breathing zone air samples were collected per shift from plasma welding and cutting workers in six industries. Total welding fume, chromium (7440473), and nickel (7440020) concentrations were determined. The standard for welding fumes in Holland is 5mg/m3, and was exceeded in plasma cutting of stainless steel when local exhaust ventilation was not present. Fume concentration was below standard levels when ventilation was present or when the cutting was done under water. Only two industries gave detectable amounts of hexavalent chromium (18540299) in concentrations from 20 to 40 micrograms/cubic meter (microg/m3). Total chromium concentrations were found up to 440microg/m3, which was below the Dutch standard of 500microg/m3. Concentrations of nickel were detected up to 260microg/m3, even when an alloy with 30 to 35 percent nickel was cut. Nitrogen-dioxide (10102440) levels were below the standard of 9mg/m3, with plasma welding giving readings up to 0.2mg/m3 and plasma cutting up to 1.1mg/m3. A peak concentration of 7mg/m3 was noted in one industry during plasma cutting of stainless steel. Nitrous-oxide (10024972) concentrations were well below the standards. Microplasma welding air samples did give indication of some high ozone (10028156) concentrations, and this situation was improved through the placing of a glass screen on the table between the torch and the worker's face. This also enabled the worker to be protected against ultraviolet radiation."
1516587,Van Der Putte et al. 1982,Respiration and osmoregulation in rainbow trout (Salmo gairdneri) exposed to hexavalent chromium at different pH values,"HEEP COPYRIGHT: BIOL ABS. Recordings were made of the ventilation frequency, coughing rate and O2 uptake rate of rainbow trout (S.gairdneri) subjected for 4 days to sublethal levels of Cr6+. Experiments were conducted at pH values of 7.8 and 6.5 and concentrations ranging between 5-50 and 1-10 mg/l Cr, respectively. During exposure no significant effect of Cr on O2 uptake rate was detected. The ventilation frequency and coughing rate increased proportionally to an increase in metal concentration, with fish being more susceptible at the lower pH. Alterations in blood and plasma variables determined after exposure included a significant dose-dependent decrease in plasma osmolality and some electrolyte concentrations and an increase in Hb, hematocrit, plasma glucose and lactate levels. The pattern of these changes was dependent on pH and exposure concentration and seemed to be related with Cr-induced histological alterations. At pH 7.8 and 6.5 an osmoregulatory and respiratory dysfunction were part of the physiological mechanism of Cr6+ toxicity.","Respiration and osmoregulation in rainbow trout (Salmo gairdneri) exposed to hexavalent chromium at different pH values Abs: HEEP COPYRIGHT: BIOL ABS. Recordings were made of the ventilation frequency, coughing rate and O2 uptake rate of rainbow trout (S.gairdneri) subjected for 4 days to sublethal levels of Cr6+. Experiments were conducted at pH values of 7.8 and 6.5 and concentrations ranging between 5-50 and 1-10 mg/l Cr, respectively. During exposure no significant effect of Cr on O2 uptake rate was detected. The ventilation frequency and coughing rate increased proportionally to an increase in metal concentration, with fish being more susceptible at the lower pH. Alterations in blood and plasma variables determined after exposure included a significant dose-dependent decrease in plasma osmolality and some electrolyte concentrations and an increase in Hb, hematocrit, plasma glucose and lactate levels. The pattern of these changes was dependent on pH and exposure concentration and seemed to be related with Cr-induced histological alterations. At pH 7.8 and 6.5 an osmoregulatory and respiratory dysfunction were part of the physiological mechanism of Cr6+ toxicity."
1516576,Van Bemst et al. 2600,Interlaboratory calibration of a standardised analytical method of hexavalent and total chromium in welding fumes,"The International Institute of Welding had 4 laboratories conduct a comparative analysis of the fumes generated from stainless-steel coated electrodes and MIG wires, to determine the reliability of the following procedures. All the fumes produced during a welding run were collected on paper filter. Hexavalent chromium was dissolved from the collected solids by heating of a sample with a mixture of aqueous sodium hydroxide and sodium carbonate. After adjustment of the volume of the extract, its Cr(VI) content was determined by atomic absorption spectrophotometry. To dissolve all the chrome in a sample, the solids were treated with a mixture of hydrochloric, nitric and hydrofluoric acids, with subsequent addition of perchloric acid. The rest of the determination was the same as for Cr(VI). Total chromium can also be determined by fusing a sample with potassium hydrogen sulfate, dissolving the cake with sulfuric acid, and determining the chromium in the resulting solution. The good repro","Interlaboratory calibration of a standardised analytical method of hexavalent and total chromium in welding fumes Abs: The International Institute of Welding had 4 laboratories conduct a comparative analysis of the fumes generated from stainless-steel coated electrodes and MIG wires, to determine the reliability of the following procedures. All the fumes produced during a welding run were collected on paper filter. Hexavalent chromium was dissolved from the collected solids by heating of a sample with a mixture of aqueous sodium hydroxide and sodium carbonate. After adjustment of the volume of the extract, its Cr(VI) content was determined by atomic absorption spectrophotometry. To dissolve all the chrome in a sample, the solids were treated with a mixture of hydrochloric, nitric and hydrofluoric acids, with subsequent addition of perchloric acid. The rest of the determination was the same as for Cr(VI). Total chromium can also be determined by fusing a sample with potassium hydrogen sulfate, dissolving the cake with sulfuric acid, and determining the chromium in the resulting solution. The good repro"
1516571,Usmani et al. 1991,"Activated carbon from indigenous inferior woods: Part IV. Adsorption of copper, zinc and hexavalent chromium: Optimum contact time and adsorption behaviour","BIOSIS COPYRIGHT: BIOL ABS. The effect of contact time, amount of carbon and general adsorption behaviour of copper, zinc and hexavalent chromium has been determined from their aqueous solutions by an activated carbon prepared from Eucalyptus (E. camaldulensis). It has been found that in each case, amount of carbon has no significant effect on the optimum contact time required for maximum metal adsorption. However, carbon dose significantly affects the amount of metal adsorbed. The adsorption of copper is found to be thrice that of zinc and chromium on the basis of initial metal ion concentration using the same amount of carbon. The results further show that when two or three metals are in the same solution, they complete for adsorption sites. However, the adsorption of zinc is hindered and reduced by 50% in the presence of Cu and Cr+6.","Activated carbon from indigenous inferior woods: Part IV. Adsorption of copper, zinc and hexavalent chromium: Optimum contact time and adsorption behaviour Abs: BIOSIS COPYRIGHT: BIOL ABS. The effect of contact time, amount of carbon and general adsorption behaviour of copper, zinc and hexavalent chromium has been determined from their aqueous solutions by an activated carbon prepared from Eucalyptus (E. camaldulensis). It has been found that in each case, amount of carbon has no significant effect on the optimum contact time required for maximum metal adsorption. However, carbon dose significantly affects the amount of metal adsorbed. The adsorption of copper is found to be thrice that of zinc and chromium on the basis of initial metal ion concentration using the same amount of carbon. The results further show that when two or three metals are in the same solution, they complete for adsorption sites. However, the adsorption of zinc is hindered and reduced by 50% in the presence of Cu and Cr+6."
1516567,Umile and  Huber 1994,Determination of hexavalent chromium and accompanying anions in one run using isocratic ion chromatography with column switching,Biosis copyright: biol abs. rrm research article heavy metal analysis toxic metal,Determination of hexavalent chromium and accompanying anions in one run using isocratic ion chromatography with column switching Abs: Biosis copyright: biol abs. rrm research article heavy metal analysis toxic metal
1516562,Ul Haq and  Shakoori 1998,"Short communication: Microbiological treatment of industrial wastes containing toxic chromium involving successive use of bacteria, yeast and algae","BIOSIS COPYRIGHT: BIOL ABS. Bacteria, yeasts, protozoa and algae, observed in industrial effluents from tanneries, were checked for their possible use in the detoxification of polluted water. Two bacterial strains were found to be highly resistant to CrVI. Several bacteria, yeasts and algae were observed to be capable of reducing CrVI to CrIII.","Short communication: Microbiological treatment of industrial wastes containing toxic chromium involving successive use of bacteria, yeast and algae Abs: BIOSIS COPYRIGHT: BIOL ABS. Bacteria, yeasts, protozoa and algae, observed in industrial effluents from tanneries, were checked for their possible use in the detoxification of polluted water. Two bacterial strains were found to be highly resistant to CrVI. Several bacteria, yeasts and algae were observed to be capable of reducing CrVI to CrIII."
1516556,Turick et al. 1996,Reduction of crvi in contaminated soil employing indigenous microflora,Biosis copyright: biol abs. rrm meeting abstract hexavalent chromium heavy metal toxicity bioremediation,Reduction of crvi in contaminated soil employing indigenous microflora Abs: Biosis copyright: biol abs. rrm meeting abstract hexavalent chromium heavy metal toxicity bioremediation
1516555,Turick and  Apel 1996,Bioprocess development for hexavalent chromium reduction,Biosis copyright: biol abs. rrm meeting abstract bacteria environmental toxin pollutant bioremediation,Bioprocess development for hexavalent chromium reduction Abs: Biosis copyright: biol abs. rrm meeting abstract bacteria environmental toxin pollutant bioremediation
1516554,Tully et al. 1999,New biomarkers of toxicity for four high priority heavy metal pollutants,Biosis copyright: biol abs. rrm new biomarkers of toxicity for four high priority heavy metal pollutantsymeeting abstract hepg2 cell line heavy metal toxicity biomarker expression in-vitro environmental toxicity model system human hepatoma cell line lead environmental pollutant toxicity cadmium chromium-(iii) chromium-(vi) pollution toxicology,New biomarkers of toxicity for four high priority heavy metal pollutants Abs: Biosis copyright: biol abs. rrm new biomarkers of toxicity for four high priority heavy metal pollutantsymeeting abstract hepg2 cell line heavy metal toxicity biomarker expression in-vitro environmental toxicity model system human hepatoma cell line lead environmental pollutant toxicity cadmium chromium-(iii) chromium-(vi) pollution toxicology
1516553,Tucker and  Carson 1985,Deactivation Of Hazardous Chemical Wastes,"Methods to deactivate hazardous chemical wastes are reviewed. Hazardous chemical wastes may be toxic, reactive, corrosive, radioactive, carcinogenic, mutagenic, or teratogenic. Deactivation by chemical conversion, removal of hazardous constituents, and stabilization are examined. Deactivation by chemical conversion is a process by which a waste or constituent of the waste is transformed to at least one substance that is less hazardous than and chemically different from the original material. Chemical conversion processes and the types of waste to which they are applicable include: wet oxidation for a variety of organic compounds; ozonation used for phenols, cyanides, and organic lead (7439921) compounds in wastewaters; molten salt combustion applicable to a variety of organic compounds; electrochemical oxidation for cyanate (661201), thiocyanate (302045), acetate (71501), phenols, and cresols; treatment with formaldehyde (50000) for chromium(VI) (18540299), cyanide ion (57125), and metal/cyanide complexes; catalytic reduction with metal powder employed with chlorinated organic compounds in wastewaters; catalytic hydrogenation for polychlorinated hydrocarbons; dechlorination for polychlorinated organic compounds; destruction by microwave plasma for pesticides and polychlorinated biphenyls; hydrolysis for organophosphorus and carbamate (302114) pesticides; and neutralization for strong acids and alkalis. Each process is described and discussed. Processes for the removal of hazardous constituents which are examined include: adsorption on carbon, ion exchange, cementation, precipitation, liquid/liquid extraction, ultrafiltration; reverse osmosis; and electrolytic reduction. Stabilization is also discussed. This is a process by which the waste is fixed in cement or other material, is treated to form a hardened material, or is encapsulated in an inert substance. Solidification with cement, thermoplastic materials, or organic polymers is described. Encapsulation, solidification by self cementation or lime based processes, and vitrification are also examined. The authors conclude that deactivation lowers worker exposure, decreases storage needs, lowers handling and transportation costs, and has a smaller impact on the environment.","Deactivation Of Hazardous Chemical Wastes Abs: Methods to deactivate hazardous chemical wastes are reviewed. Hazardous chemical wastes may be toxic, reactive, corrosive, radioactive, carcinogenic, mutagenic, or teratogenic. Deactivation by chemical conversion, removal of hazardous constituents, and stabilization are examined. Deactivation by chemical conversion is a process by which a waste or constituent of the waste is transformed to at least one substance that is less hazardous than and chemically different from the original material. Chemical conversion processes and the types of waste to which they are applicable include: wet oxidation for a variety of organic compounds; ozonation used for phenols, cyanides, and organic lead (7439921) compounds in wastewaters; molten salt combustion applicable to a variety of organic compounds; electrochemical oxidation for cyanate (661201), thiocyanate (302045), acetate (71501), phenols, and cresols; treatment with formaldehyde (50000) for chromium(VI) (18540299), cyanide ion (57125), and metal/cyanide complexes; catalytic reduction with metal powder employed with chlorinated organic compounds in wastewaters; catalytic hydrogenation for polychlorinated hydrocarbons; dechlorination for polychlorinated organic compounds; destruction by microwave plasma for pesticides and polychlorinated biphenyls; hydrolysis for organophosphorus and carbamate (302114) pesticides; and neutralization for strong acids and alkalis. Each process is described and discussed. Processes for the removal of hazardous constituents which are examined include: adsorption on carbon, ion exchange, cementation, precipitation, liquid/liquid extraction, ultrafiltration; reverse osmosis; and electrolytic reduction. Stabilization is also discussed. This is a process by which the waste is fixed in cement or other material, is treated to form a hardened material, or is encapsulated in an inert substance. Solidification with cement, thermoplastic materials, or organic polymers is described. Encapsulation, solidification by self cementation or lime based processes, and vitrification are also examined. The authors conclude that deactivation lowers worker exposure, decreases storage needs, lowers handling and transportation costs, and has a smaller impact on the environment."
1516552,Tubbs et al. 2202,"Health Hazard Evaluation Report No. HETA-89-364-2202, ARMCO Advanced Materials Corporation, Butler, Pennsylvania","In response to a management request, an evaluation was made of possible hazardous working conditions at ARMCO Advanced Materials Corporation (SIC-3312), Butler, Pennsylvania. ARMCO produced primarily specialty steel products. An indirect method of electric heating was used at the facility to make steel. Concern was expressed about employee exposures to infrasound, electromagnetic radiation, and various dusts throughout the melt shop. The investigation was then expanded to include radiofrequency exposures at the Ultra-Rapid Annealing (URA) furnace located in the Strip Coating and Silicon Anneal Building (SCSAB). Air samples analyzed indicated that the recommended levels were being exceeded for chromium (7440473), manganese (7439965) and lead (7439921). Radiofrequency radiation measurements at the URA furnace and the visible radiation levels near the electric arc furnaces in the melt shops exceeded the appropriate evaluation criteria. The authors conclude that health hazards existed during the survey from excessive airborne levels of hexavalent chromium, manganese, and lead, high levels of optical radiation near the electric arc furnaces, and radiofrequency radiation at the URA furnace. The authors recommended measures to lower these exposures and suggested the institution of medical and environmental surveillance programs.","Health Hazard Evaluation Report No. HETA-89-364-2202, ARMCO Advanced Materials Corporation, Butler, Pennsylvania Abs: In response to a management request, an evaluation was made of possible hazardous working conditions at ARMCO Advanced Materials Corporation (SIC-3312), Butler, Pennsylvania. ARMCO produced primarily specialty steel products. An indirect method of electric heating was used at the facility to make steel. Concern was expressed about employee exposures to infrasound, electromagnetic radiation, and various dusts throughout the melt shop. The investigation was then expanded to include radiofrequency exposures at the Ultra-Rapid Annealing (URA) furnace located in the Strip Coating and Silicon Anneal Building (SCSAB). Air samples analyzed indicated that the recommended levels were being exceeded for chromium (7440473), manganese (7439965) and lead (7439921). Radiofrequency radiation measurements at the URA furnace and the visible radiation levels near the electric arc furnaces in the melt shops exceeded the appropriate evaluation criteria. The authors conclude that health hazards existed during the survey from excessive airborne levels of hexavalent chromium, manganese, and lead, high levels of optical radiation near the electric arc furnaces, and radiofrequency radiation at the URA furnace. The authors recommended measures to lower these exposures and suggested the institution of medical and environmental surveillance programs."
1516550,Tsukamoto et al. 1993,Influence of Irritants on Lymph Node Cell Proliferation and the Detection of Contact Sensitivity to Metal Salts in the Murine Local Lymph Node Assay AU - Ikarashi Y,"A study was conducted to examine whether irritants, such as sodium-lauryl-sulfate (151213) (SLS) and dimethyl-sulfoxide (67685) (DMSO) would cause lymphocyte proliferation in draining lymph nodes using the local lymph node assay (LLNA). A small increase in lymph node cell proliferation compared with aqueous solution alone was noted following exposure to DMSO or SLS aqueous solution. A significant increase in lymph node cell (LNC) proliferation was noted following exposure to SLS in DMSO. The effect of addition of the irritants in a vehicle on the detection of contact sensitivity to metal allergens was also examined. Increased LNC proliferation occurred following the application of potassium-dichromate (7778509) and nickel-sulfate (7786814) in DMSO or SLS aqueous solution. A significant proliferative response of LNC was also noted following exposure to metal allergen with SLS in DMSO. This did not induce a significant increase in stimulation index. The authors suggest that irritants enhance the LNC proliferative response to metal allergens. The authors conclude that using SLS in aqueous solution to detect sensitivity to water soluble allergens is effective in the LLNA and that the use of DMSO is also effective as an application vehicle.","Influence of Irritants on Lymph Node Cell Proliferation and the Detection of Contact Sensitivity to Metal Salts in the Murine Local Lymph Node Assay AU - Ikarashi Y Abs: A study was conducted to examine whether irritants, such as sodium-lauryl-sulfate (151213) (SLS) and dimethyl-sulfoxide (67685) (DMSO) would cause lymphocyte proliferation in draining lymph nodes using the local lymph node assay (LLNA). A small increase in lymph node cell proliferation compared with aqueous solution alone was noted following exposure to DMSO or SLS aqueous solution. A significant increase in lymph node cell (LNC) proliferation was noted following exposure to SLS in DMSO. The effect of addition of the irritants in a vehicle on the detection of contact sensitivity to metal allergens was also examined. Increased LNC proliferation occurred following the application of potassium-dichromate (7778509) and nickel-sulfate (7786814) in DMSO or SLS aqueous solution. A significant proliferative response of LNC was also noted following exposure to metal allergen with SLS in DMSO. This did not induce a significant increase in stimulation index. The authors suggest that irritants enhance the LNC proliferative response to metal allergens. The authors conclude that using SLS in aqueous solution to detect sensitivity to water soluble allergens is effective in the LLNA and that the use of DMSO is also effective as an application vehicle."
1516546,Trojanowicz et al. 1992,Speciation of chromium by ion-pair chromatography with postcolumn spectrophotometric detection,High performance ion-pair chromatographic method of Cr(III) and Cr(VI) separation using phosphate buffer containing tetrabutylammonium bromide as eluent was developed. Post column derivatization based on Cr(VI) reaction with diphenylcarbazide and spectrophotometry monitoring of eluate at 560 nm was employed with Cr(III) oxidation to Cr(VI) using cerium(IV) sulphate. Detection limit was estimated as 7 ng/ml Cr(IIl) and 13 ng/ml Cr(VI).,Speciation of chromium by ion-pair chromatography with postcolumn spectrophotometric detection Abs: High performance ion-pair chromatographic method of Cr(III) and Cr(VI) separation using phosphate buffer containing tetrabutylammonium bromide as eluent was developed. Post column derivatization based on Cr(VI) reaction with diphenylcarbazide and spectrophotometry monitoring of eluate at 560 nm was employed with Cr(III) oxidation to Cr(VI) using cerium(IV) sulphate. Detection limit was estimated as 7 ng/ml Cr(IIl) and 13 ng/ml Cr(VI).
1516545,Trillas et al. 1991,Photoreduction of chromium(VI) over cadmium sulfide supported on a glass matrix,"BIOSIS COPYRIGHT: BIOL ABS. The photocatalytic elimination of Cr(VI) from aqueous solutions using CdS supported on glass pearls as catalyst is investigated. The study has been carried out by measuring the amount of Cr(VI) eliminated at different pH, initial Cr(VI) concentrations and temperatures. It has been observed that after flushing dilute Cr(VI) solutions at a wide range of pH (from 5 to 10) through the CdS-coated glass pearls, 100% of Cr(VI) elimination is achieved. By means of this experimental system the kinetics of Cr(VI) photoreduction to Cr(III) over CdS in flow conditions has been determined. Finally, the stability of CdS in long-term experiments and the application of this catalytic method in a real case has been studied.","Photoreduction of chromium(VI) over cadmium sulfide supported on a glass matrix Abs: BIOSIS COPYRIGHT: BIOL ABS. The photocatalytic elimination of Cr(VI) from aqueous solutions using CdS supported on glass pearls as catalyst is investigated. The study has been carried out by measuring the amount of Cr(VI) eliminated at different pH, initial Cr(VI) concentrations and temperatures. It has been observed that after flushing dilute Cr(VI) solutions at a wide range of pH (from 5 to 10) through the CdS-coated glass pearls, 100% of Cr(VI) elimination is achieved. By means of this experimental system the kinetics of Cr(VI) photoreduction to Cr(III) over CdS in flow conditions has been determined. Finally, the stability of CdS in long-term experiments and the application of this catalytic method in a real case has been studied."
1516540,Toniolo and  Taioli 1995,Development of Biomarkers of Human Exposure to Carcinogens: The Example of DNA-Protein Cross-Links,"The development of biomarkers of human exposure to carcinogenic substances and the example of DNA/protein cross links (DPX) as a marker were discussed. In light of the limitations of traditional epidemiologic studies, the advantages offered by biomarkers in modern molecular epidemiology included the availability of estimates of biologically effective exposure or preclinical disease response after exposure. Biomarkers were also more biologically informative and less prone to misclassification bias. Except for simple biochemical measurements, very few biological markers have been developed for use in chronic disease epidemiology. The development of a biomarker was outlined. New biomarkers are conceived in laboratories and undergo extensive experimental testing. Once a biomarker becomes available, preliminary field tests can be conducted to collect minimal background data, including how the biomarker performs in healthy, nonexposed people and its intra and intervariability. The example of DPX as a biomarker of human exposure to hexavalent-chromium (18540299) and the difficulties inherent in the process of biomarker development were presented. DPX detection involved the selective precipitation of DNA containing crosslinked protein. When initially evaluated for reproducibility in small cross sectional studies, it showed increased DPX levels in peripheral lymphocytes in subjects potentially exposed to low levels of occupational or residential chromates. When further tested in a small chromium plating factory, an unexpected dose response relationship with exposure was seen. The unexpected results were attributed to a combination of the effects of chronic toxicity of chromate and study design. Study controls had been office workers at the chromate factory who could have been chronically exposed to chromate. Blood lymphocytes undergo cell death more rapidly in subjects exposed to elevated, chronic ambient levels of chromate. The authors conclude that alternative study designs underway may produce different associations for DPX and exposure.","Development of Biomarkers of Human Exposure to Carcinogens: The Example of DNA-Protein Cross-Links Abs: The development of biomarkers of human exposure to carcinogenic substances and the example of DNA/protein cross links (DPX) as a marker were discussed. In light of the limitations of traditional epidemiologic studies, the advantages offered by biomarkers in modern molecular epidemiology included the availability of estimates of biologically effective exposure or preclinical disease response after exposure. Biomarkers were also more biologically informative and less prone to misclassification bias. Except for simple biochemical measurements, very few biological markers have been developed for use in chronic disease epidemiology. The development of a biomarker was outlined. New biomarkers are conceived in laboratories and undergo extensive experimental testing. Once a biomarker becomes available, preliminary field tests can be conducted to collect minimal background data, including how the biomarker performs in healthy, nonexposed people and its intra and intervariability. The example of DPX as a biomarker of human exposure to hexavalent-chromium (18540299) and the difficulties inherent in the process of biomarker development were presented. DPX detection involved the selective precipitation of DNA containing crosslinked protein. When initially evaluated for reproducibility in small cross sectional studies, it showed increased DPX levels in peripheral lymphocytes in subjects potentially exposed to low levels of occupational or residential chromates. When further tested in a small chromium plating factory, an unexpected dose response relationship with exposure was seen. The unexpected results were attributed to a combination of the effects of chronic toxicity of chromate and study design. Study controls had been office workers at the chromate factory who could have been chronically exposed to chromate. Blood lymphocytes undergo cell death more rapidly in subjects exposed to elevated, chronic ambient levels of chromate. The authors conclude that alternative study designs underway may produce different associations for DPX and exposure."
1516535,Todd and  Timbie ,"Preliminary Survey of Wood Preservative Production Facility at Koppers Company, Inc., Forest Products Group Specialty Wood Chemicals Division, Valparaiso, Indiana","The Koppers Company, Incorporated, a chromated copper arsenate manufacturing facility (SIC-2851) in Valparaiso, Indiana was surveyed on July 24, 1979 to evaluate work practices, exposure controls, past exposures, and medical, industrial hygiene, and safety programs. The facility employs five workers. Two NIOSH sampling methods were used to measure arsenic (7440382), chromium (7440473), and copper (7440508) at two sites for 5 hours at each site. The company provided a comprehensive medical surveillance program, periodic air sampling and exhaust system maintenance, and mandatory protective clothing and showers. Airborne levels recorded were 19.0 and 135.2 micrograms per cubic meter (m3) for copper, 4.2 and 22.2 micrograms/m3 for total chromium, 1.1 and 15.2 micrograms/m3 for hexavalent chromium, and 4.2 and 24.2 micrograms/m3 for arsenic. The authors suggest that arsenic exposure exceeded the OSHA permissible exposure limit of 10 micrograms/m3 averaged over an 8 hour period. The OSHA permissible exposure limits of 1 milligram per cubic meter (mg/m3) averaged over an 8 hour period for copper dust and mists and 0.5 mg/m3 for chromic acid were not exceeded.","Preliminary Survey of Wood Preservative Production Facility at Koppers Company, Inc., Forest Products Group Specialty Wood Chemicals Division, Valparaiso, Indiana Abs: The Koppers Company, Incorporated, a chromated copper arsenate manufacturing facility (SIC-2851) in Valparaiso, Indiana was surveyed on July 24, 1979 to evaluate work practices, exposure controls, past exposures, and medical, industrial hygiene, and safety programs. The facility employs five workers. Two NIOSH sampling methods were used to measure arsenic (7440382), chromium (7440473), and copper (7440508) at two sites for 5 hours at each site. The company provided a comprehensive medical surveillance program, periodic air sampling and exhaust system maintenance, and mandatory protective clothing and showers. Airborne levels recorded were 19.0 and 135.2 micrograms per cubic meter (m3) for copper, 4.2 and 22.2 micrograms/m3 for total chromium, 1.1 and 15.2 micrograms/m3 for hexavalent chromium, and 4.2 and 24.2 micrograms/m3 for arsenic. The authors suggest that arsenic exposure exceeded the OSHA permissible exposure limit of 10 micrograms/m3 averaged over an 8 hour period. The OSHA permissible exposure limits of 1 milligram per cubic meter (mg/m3) averaged over an 8 hour period for copper dust and mists and 0.5 mg/m3 for chromic acid were not exceeded."
1516534,Tiwari et al. 1989,Removal of toxic metals from electroplating industries (effect of pH on removal by adsorption),"BIOSIS COPYRIGHT: BIOL ABS. Attempts were made to remove chromium (VI), copper and nickel from dilute solutions (concentrations ranging from 5 to 50 mg) by an activated carbon adsorption technique. Studies were restricted to pH range from 5.5 to 8.0. Adsorption of chromium (VI) was found to exhibit a peak value at pH 5.5 and copper at 8.0. The adsorption of nickel was found to be appreciable in both the mediums but removal was faster in alkaline medium.","Removal of toxic metals from electroplating industries (effect of pH on removal by adsorption) Abs: BIOSIS COPYRIGHT: BIOL ABS. Attempts were made to remove chromium (VI), copper and nickel from dilute solutions (concentrations ranging from 5 to 50 mg) by an activated carbon adsorption technique. Studies were restricted to pH range from 5.5 to 8.0. Adsorption of chromium (VI) was found to exhibit a peak value at pH 5.5 and copper at 8.0. The adsorption of nickel was found to be appreciable in both the mediums but removal was faster in alkaline medium."
1516533,Tittlebaum 1989,Investigation of hazardous characteristics of refinery wastewater sludges. AU - WIMBERLEY WF,"BIOSIS COPYRIGHT: BIOL ABS. Much attention has been given to groundwater contamination due to the release of hazardous constituents from treatment and disposal facilities. Since some of the constituents entered groundwater aquifers in much shorter times than has been calculated, regulatory agencies have become concerned that hazardous constituents may be escaping from units not currently regulated under hazardous waste management programs. One of the major concerns of regulators is that unlined earthen surface impoundments in industrial wastewater treatment trains may be leaking heavy metals such as chromium and other hazardous constituents into the groundwater. The Environmental Protection Agency is moving toward bringing such impoundments under the Resource Conservation and Recovery Act (RCRA) regulations. In addition, EPA is now proposing to list hexavalent chromium as a hazardous air pollutant due to its possible release from the mist of cooling towers, citing hexavalent chromium's potent carc","Investigation of hazardous characteristics of refinery wastewater sludges. AU - WIMBERLEY WF Abs: BIOSIS COPYRIGHT: BIOL ABS. Much attention has been given to groundwater contamination due to the release of hazardous constituents from treatment and disposal facilities. Since some of the constituents entered groundwater aquifers in much shorter times than has been calculated, regulatory agencies have become concerned that hazardous constituents may be escaping from units not currently regulated under hazardous waste management programs. One of the major concerns of regulators is that unlined earthen surface impoundments in industrial wastewater treatment trains may be leaking heavy metals such as chromium and other hazardous constituents into the groundwater. The Environmental Protection Agency is moving toward bringing such impoundments under the Resource Conservation and Recovery Act (RCRA) regulations. In addition, EPA is now proposing to list hexavalent chromium as a hazardous air pollutant due to its possible release from the mist of cooling towers, citing hexavalent chromium's potent carc"
1516530,Thorsen and  Stensby 1982,Impact of chromium waste spills in glacial till soils,"HMTC A report of illegal dumping near a chromium plating facility was received by the Wisconsin Dept. of Natural Resources (WDNR). Response to the spill included site investigation, cleanup strategy, and negotiations for a cleanup agreement with the plating firm. Initial analyses of the ground water showed hexavalent chromium up to 1200 ppm. Chromium contamination of the soil and ground water was severe but localized. The remedial action plans negotiated by WDNR and the plating company are discussed and the steps taken for cleanup are given.","Impact of chromium waste spills in glacial till soils Abs: HMTC A report of illegal dumping near a chromium plating facility was received by the Wisconsin Dept. of Natural Resources (WDNR). Response to the spill included site investigation, cleanup strategy, and negotiations for a cleanup agreement with the plating firm. Initial analyses of the ground water showed hexavalent chromium up to 1200 ppm. Chromium contamination of the soil and ground water was severe but localized. The remedial action plans negotiated by WDNR and the plating company are discussed and the steps taken for cleanup are given."
1516525,Thornton and  Amonette 1999,Hydrogen sulfide gas treatment of Cr(VI)-contaminated sediment samples from a plating-waste disposal site: Implications for in-situ remediation,"BIOSIS COPYRIGHT: BIOL ABS. Twenty sediment samples were collected at depths ranging from 5 to 100 feet beneath a chromate-contaminated plating-waste site and analyzed for Cr(VI), total chromium, and related constituents. Three of the samples were selected for treatment with dilute hydrogen sulfide (H2S) gas to evaluate this approach as a possible in-situ remediation technique. Gas treatment was performed in soil-packed columns using 100 ppm (muL L-1) H2S mixtures, and treatment progress was assessed by monitoring the breakthrough of H2S. Evaluation of treatment efficacy included (1) water-leaching of the treated and untreated columns for 10 days, (2) repetitive extraction of treated and untreated subsamples by water, 0.01 M phosphate (pH 7) or 6 M HCl solutions, and (3) Cr K-edge X-ray absorption near-edge structure (XANES) spectroscopy of treated and untreated subsamples. Results of the water-leaching studies show ed that the H2S treatment decreased Cr(VI) levels in the column effluent by 90% to nearly 100%. Repetitive extractions by water and phosphate solutions echoed these results, and the extraction by HCl released only 35-40% as much Cr in the treated as in the untreated samples. Analysis by XANES spectroscopy showed that a substantial portion of the Cr in the samples remained as Cr(VI) after treatment, even though it was not available to the water and phosphate extracting solutions. These results indicate that the residual Cr(VI) was sequestered in unreacted grain interiors under impermeable coatings formed during H2S treatment. However, this fraction is immobile and thus unavailable to the environment.","Hydrogen sulfide gas treatment of Cr(VI)-contaminated sediment samples from a plating-waste disposal site: Implications for in-situ remediation Abs: BIOSIS COPYRIGHT: BIOL ABS. Twenty sediment samples were collected at depths ranging from 5 to 100 feet beneath a chromate-contaminated plating-waste site and analyzed for Cr(VI), total chromium, and related constituents. Three of the samples were selected for treatment with dilute hydrogen sulfide (H2S) gas to evaluate this approach as a possible in-situ remediation technique. Gas treatment was performed in soil-packed columns using 100 ppm (muL L-1) H2S mixtures, and treatment progress was assessed by monitoring the breakthrough of H2S. Evaluation of treatment efficacy included (1) water-leaching of the treated and untreated columns for 10 days, (2) repetitive extraction of treated and untreated subsamples by water, 0.01 M phosphate (pH 7) or 6 M HCl solutions, and (3) Cr K-edge X-ray absorption near-edge structure (XANES) spectroscopy of treated and untreated subsamples. Results of the water-leaching studies show ed that the H2S treatment decreased Cr(VI) levels in the column effluent by 90% to nearly 100%. Repetitive extractions by water and phosphate solutions echoed these results, and the extraction by HCl released only 35-40% as much Cr in the treated as in the untreated samples. Analysis by XANES spectroscopy showed that a substantial portion of the Cr in the samples remained as Cr(VI) after treatment, even though it was not available to the water and phosphate extracting solutions. These results indicate that the residual Cr(VI) was sequestered in unreacted grain interiors under impermeable coatings formed during H2S treatment. However, this fraction is immobile and thus unavailable to the environment."
1516522,Thomas et al. 1990,UV multiwavelength absorptiometry (UVMA) for the examination of natural waters and wastewaters: Part III. Determination of chromium(VI),"BIOSIS COPYRIGHT: BIOL ABS. Chromium(VI) is one of the major pollutants of waters and unfortunately, at the present ime, it cannot be determined with a simple and fast method. The use of the ultraviolet multiwavelength absorptiometry (UVMA) for chromium determination is very conveninet for that purpose because of the well known absorption properties of chromium. Two methods are proposed which lead to different sensitivity. The first one needs hydroxide sodium addition for the measurement of the chromate form and has detect limit of 4 mug/ml. The second does not use any reagent and determines directly both dichromate and chromate forms, whose sum gives the concentration of chromium(VI). This last procedure is faster but the characteristics are slightly less precise. These proposed methods have been compared with a reference method, for natural waters and treated wastewaters, with good agreement. Thiese procedure can be used for water quality monitoring.","UV multiwavelength absorptiometry (UVMA) for the examination of natural waters and wastewaters: Part III. Determination of chromium(VI) Abs: BIOSIS COPYRIGHT: BIOL ABS. Chromium(VI) is one of the major pollutants of waters and unfortunately, at the present ime, it cannot be determined with a simple and fast method. The use of the ultraviolet multiwavelength absorptiometry (UVMA) for chromium determination is very conveninet for that purpose because of the well known absorption properties of chromium. Two methods are proposed which lead to different sensitivity. The first one needs hydroxide sodium addition for the measurement of the chromate form and has detect limit of 4 mug/ml. The second does not use any reagent and determines directly both dichromate and chromate forms, whose sum gives the concentration of chromium(VI). This last procedure is faster but the characteristics are slightly less precise. These proposed methods have been compared with a reference method, for natural waters and treated wastewaters, with good agreement. Thiese procedure can be used for water quality monitoring."
1516521,Tharr 1991,Workplace Exposures at a Waste-to-Energy Facility,"Breathing zone and environmental samples were analyzed for total and respirable dust, crystalline silica (14808607), asbestos (1332214), hexavalent-chromium (18540299) (Cr+6), carbon-monoxide (630080), nitrogen oxides, and trace metals at a waste to energy conversion facility. The facility typically incinerated municipal trash at approximately 1400 degrees-F and produced steam in two 360 ton capacity boilers that was sold directly or converted to electricity by means of an on site turbine. The facility operated 24 hours a day and usually employed 50 persons. Workplace temperature and humidities were also measured. Total dust concentrations ranged from 1.2 to 11.5mg/m3. Breathing zone respirable dust concentrations were 0.3 to 0.7mg/m3. Significant concentrations of airborne aluminum (7429905), cadmium (7440439), chromium (7440473), copper (7440508), iron 7439896), nickel (7440020), and lead (7439921) were detected. Soluble Cr+6 was not detected. Insoluble Cr+6 was detected at concentrations on the order of 0.001mg/m3. Significant amounts of amosite (12172735) were detected in the breathing zone and environmental samples. Crystalline silica and nitrogen oxides were not detected. Except for one sample that yielded a concentration of 5 parts per million, carbon-monoxide was not detected. Workplace ambient temperatures ranged from 83 to 115 degrees and relative humidities from 18 to 50%. The author concludes that workers at the waste to energy facility are potentially exposed to high concentrations of total dust, metals, and asbestos and experience heat stress problems.","Workplace Exposures at a Waste-to-Energy Facility Abs: Breathing zone and environmental samples were analyzed for total and respirable dust, crystalline silica (14808607), asbestos (1332214), hexavalent-chromium (18540299) (Cr+6), carbon-monoxide (630080), nitrogen oxides, and trace metals at a waste to energy conversion facility. The facility typically incinerated municipal trash at approximately 1400 degrees-F and produced steam in two 360 ton capacity boilers that was sold directly or converted to electricity by means of an on site turbine. The facility operated 24 hours a day and usually employed 50 persons. Workplace temperature and humidities were also measured. Total dust concentrations ranged from 1.2 to 11.5mg/m3. Breathing zone respirable dust concentrations were 0.3 to 0.7mg/m3. Significant concentrations of airborne aluminum (7429905), cadmium (7440439), chromium (7440473), copper (7440508), iron 7439896), nickel (7440020), and lead (7439921) were detected. Soluble Cr+6 was not detected. Insoluble Cr+6 was detected at concentrations on the order of 0.001mg/m3. Significant amounts of amosite (12172735) were detected in the breathing zone and environmental samples. Crystalline silica and nitrogen oxides were not detected. Except for one sample that yielded a concentration of 5 parts per million, carbon-monoxide was not detected. Workplace ambient temperatures ranged from 83 to 115 degrees and relative humidities from 18 to 50%. The author concludes that workers at the waste to energy facility are potentially exposed to high concentrations of total dust, metals, and asbestos and experience heat stress problems."
1516520,Thaker et al. 1997,Dose and duration dependent toxicity of Cr(VI) on acid and alkaline phosphatases in six vital organs of mudskipper Periophthalmus dipes,"BIOSIS COPYRIGHT: BIOL ABS. To assess the effects of hexavalent chromium on acid and alkaline phosphatase in six vital tissues (gills, kidney, intestine, liver, brain and muscle) fishes (P. dipes) were exposed to three sublethal concentrations of Cr(VI) (5, 10 and 15 mg/l) for three different exposure durations (2, 4 and 6 days). The activity of both the enzymes showed dose and exposure duration dependent inhibition in almost all the tissues studied. However, in kidney, liver and intestine the enzyme activity was stimulated. It was evident that both dose and duration dependent alteration of enzyme activity occurred in gills and kidney. However, in other tissues predominantly exposure duration dependent alterations were observed.","Dose and duration dependent toxicity of Cr(VI) on acid and alkaline phosphatases in six vital organs of mudskipper Periophthalmus dipes Abs: BIOSIS COPYRIGHT: BIOL ABS. To assess the effects of hexavalent chromium on acid and alkaline phosphatase in six vital tissues (gills, kidney, intestine, liver, brain and muscle) fishes (P. dipes) were exposed to three sublethal concentrations of Cr(VI) (5, 10 and 15 mg/l) for three different exposure durations (2, 4 and 6 days). The activity of both the enzymes showed dose and exposure duration dependent inhibition in almost all the tissues studied. However, in kidney, liver and intestine the enzyme activity was stimulated. It was evident that both dose and duration dependent alteration of enzyme activity occurred in gills and kidney. However, in other tissues predominantly exposure duration dependent alterations were observed."
1516519,Thaker et al. 1999,Cr (VI) induced changes in the activity of few ion dependent ATPases in three vital organs of mudskipper Periophthalmus dipes (Pisces: Gobidae),"BIOSIS COPYRIGHT: BIOL ABS. Experiments were carried out to assess the dose and duration dependent influence of Cr(VI) to few ion dependent ATPases in liver, brain and muscle of a coastal euryhaline teleost Periophthalmus dipes. Fishes were exposed to three sublethal concentrations (5, 10 and 15 mg/l) of Cr(VI), prepared by using K2CrO4 with normal seawater, for three exposure duration (2, 4 and 6 days). In the present report, effects of Cr(VI) toxicity on total ATPase, (Na+,K+)-ATPase, (Ca++)-ATPase, (Mg++)-ATPase, (Ca++","Cr (VI) induced changes in the activity of few ion dependent ATPases in three vital organs of mudskipper Periophthalmus dipes (Pisces: Gobidae) Abs: BIOSIS COPYRIGHT: BIOL ABS. Experiments were carried out to assess the dose and duration dependent influence of Cr(VI) to few ion dependent ATPases in liver, brain and muscle of a coastal euryhaline teleost Periophthalmus dipes. Fishes were exposed to three sublethal concentrations (5, 10 and 15 mg/l) of Cr(VI), prepared by using K2CrO4 with normal seawater, for three exposure duration (2, 4 and 6 days). In the present report, effects of Cr(VI) toxicity on total ATPase, (Na+,K+)-ATPase, (Ca++)-ATPase, (Mg++)-ATPase, (Ca++"
1516516,Terada et al. 1989,Chemical state analysis of chromium in welding fume by high resolution x-ray fluorescence spectrometry,Biosis copyright: biol abs. rrm human occupational health,Chemical state analysis of chromium in welding fume by high resolution x-ray fluorescence spectrometry Abs: Biosis copyright: biol abs. rrm human occupational health
1516514,Temple et al. 1991,"Antimitotic agents. alterations at the 2,3-positions of ethyl (5-amino-1,2-dihydropyrido[3,4-b]pyrazin-7-yl)carbamates","The reaction of ethyl (6-amino-4-chloro-5-nitropyridin-2-yl)carbamate (2) with alpha-amino ketone oximes gave 4-[(2-oxoethyl)amino]pyridine oximes 3, which were reductively cyclized to give a series of ethyl (1,2-dihydropyrido[3,4-b]pyrazin-7-yl)carbamates (6). in another approach, alpha-nitro ketones, alpha-oximino ketones, and alpha-nitro alcohols were reduced to give alpha-amino alcohols, which were reacted with 2 to give 4-[(2-hydroxyethyl)amino]pyridines (5). oxidation of these alcohols with the chromium trioxide-pyridine reagent gave the corresponding ketones (4), which were also reductively cyclized to give 6. structure-activity relationship studies indicated that alterations at the 2- and 3-positions of the pyrazine ring of 6 had a significant effect on cytotoxicity and the inhibition of mitosis in cultured lymphoid leukemia l1210 cells. compounds that exhibited in vitro cytotoxicities at less than 1 nm showed the same level of in vivo activity, whereas the less potent compounds showed wide variations in their in vivo activity. tax - mus","Antimitotic agents. alterations at the 2,3-positions of ethyl (5-amino-1,2-dihydropyrido[3,4-b]pyrazin-7-yl)carbamates Abs: The reaction of ethyl (6-amino-4-chloro-5-nitropyridin-2-yl)carbamate (2) with alpha-amino ketone oximes gave 4-[(2-oxoethyl)amino]pyridine oximes 3, which were reductively cyclized to give a series of ethyl (1,2-dihydropyrido[3,4-b]pyrazin-7-yl)carbamates (6). in another approach, alpha-nitro ketones, alpha-oximino ketones, and alpha-nitro alcohols were reduced to give alpha-amino alcohols, which were reacted with 2 to give 4-[(2-hydroxyethyl)amino]pyridines (5). oxidation of these alcohols with the chromium trioxide-pyridine reagent gave the corresponding ketones (4), which were also reductively cyclized to give 6. structure-activity relationship studies indicated that alterations at the 2- and 3-positions of the pyrazine ring of 6 had a significant effect on cytotoxicity and the inhibition of mitosis in cultured lymphoid leukemia l1210 cells. compounds that exhibited in vitro cytotoxicities at less than 1 nm showed the same level of in vivo activity, whereas the less potent compounds showed wide variations in their in vivo activity. tax - mus"
1516513,Teasdale et al. 1989,Selective determination of chromium(VI) oxyanions using a poly-3-methylthiophene-modified electrode,BIOSIS COPYRIGHT: BIOL ABS. Poly-3-methylthiophene-modified platinum electrodes are useful for measuring trace levels of chromium(VI) oxyanions. Chromium(III) species do not interfere. The nature of the response is elucidated using scanning electron microscopy and electron microprobe analysis.,Selective determination of chromium(VI) oxyanions using a poly-3-methylthiophene-modified electrode Abs: BIOSIS COPYRIGHT: BIOL ABS. Poly-3-methylthiophene-modified platinum electrodes are useful for measuring trace levels of chromium(VI) oxyanions. Chromium(III) species do not interfere. The nature of the response is elucidated using scanning electron microscopy and electron microprobe analysis.
1516512,Taylor and  Park 1981,Cooling tower windage: A new aspect to environmental assessment,"HEEP COPYRIGHT: BIOL ABS. During the past decade the environmental impact of cooling tower drift on terrestrial environments has been a major consideration. Recent studies at the Paducah, Kentucky (USA), Gaseous Diffusion Plant suggested that there was also a significant potential for aquatic impacts. Blowdown at the Kentucky and Oak Ridge (Tennessee, USA) Gaseous Diffusion Plants (ORGDP) was engineered for zero chromate discharges to receiving streams by chromate reduction or chromate recovery procedures. Past operating experiences at the Paducah facility without chromated discharges resulted in violations (for which remedial action was taken) of USA National Pollutant Discharge Elimination Systems (NPDES) permit standards for Cr6+ and provided the impetus for this study. These episodes of noncompliance were associated with high winds, cold weather and tower operation without fan-induced draft. Under these circumstances, cooling water was lost from the sides of the tower, instead of from the top as with drift, and transported to streams as runoff. This loss of cooling water, termed windage, may impact the water quality of the regulated streams. Data were presented for several ORGDP cooling towers under varying meteorological conditions, and the potential for NPDES noncompliance discussed. In addition to demonstrating the need for uprating emissions control in a specific situation, results of the research also had generic implications for power utilities.","Cooling tower windage: A new aspect to environmental assessment Abs: HEEP COPYRIGHT: BIOL ABS. During the past decade the environmental impact of cooling tower drift on terrestrial environments has been a major consideration. Recent studies at the Paducah, Kentucky (USA), Gaseous Diffusion Plant suggested that there was also a significant potential for aquatic impacts. Blowdown at the Kentucky and Oak Ridge (Tennessee, USA) Gaseous Diffusion Plants (ORGDP) was engineered for zero chromate discharges to receiving streams by chromate reduction or chromate recovery procedures. Past operating experiences at the Paducah facility without chromated discharges resulted in violations (for which remedial action was taken) of USA National Pollutant Discharge Elimination Systems (NPDES) permit standards for Cr6+ and provided the impetus for this study. These episodes of noncompliance were associated with high winds, cold weather and tower operation without fan-induced draft. Under these circumstances, cooling water was lost from the sides of the tower, instead of from the top as with drift, and transported to streams as runoff. This loss of cooling water, termed windage, may impact the water quality of the regulated streams. Data were presented for several ORGDP cooling towers under varying meteorological conditions, and the potential for NPDES noncompliance discussed. In addition to demonstrating the need for uprating emissions control in a specific situation, results of the research also had generic implications for power utilities."
1516511,Tare and  Chaudhari 1987,Evaluation of soluble and insoluble xanthate process for the removal of heavy metals from wastewaters,Biosis copyright: biol abs. rrm water pollution hexavalent chromium removal biotechnology wastewater treatment,Evaluation of soluble and insoluble xanthate process for the removal of heavy metals from wastewaters Abs: Biosis copyright: biol abs. rrm water pollution hexavalent chromium removal biotechnology wastewater treatment
1516509,Tandon and  Aarts 1993,"Chromium, nickel and cobalt contents of some Australian cements","The total chromium, nickel and cobalt concentrations of 8 Australian Portland cements ranged from 49 to 99|g/g, 5 to 54|g/g and < =1 to 13|g/g, respectively. The water-soluble chromate concentrations of the cements ranged from 0.2 to 8.1|g/g, and the sodium sulfate-extractable chromates form 1.4 to 9.7|g/g. Results for water-soluble nickel ( < =0.2|g/g) and cobalt ( < =0.05|g/g) indicate that the metals are present only as water-insoluble compounds. The significance of the various data is considered from a dermatological point of view. Cement extracts for the analysis of water-soluble hexavalent chromium (chromates) are stable for at least 12 days. The optimum extraction time for hexavalent chromium in cement appears to be 1h. Almost 100% reduction of hexavalent chromium is possible after 1h using 100 x the stoichiometric value of iron (II) sulfate. The chromates can become gradually insolubilised when the solution from the water added is in direct contact with the cement, i.e., over a period of > 60min to 7 days, even without the addition of iron (II) sulfate.","Chromium, nickel and cobalt contents of some Australian cements Abs: The total chromium, nickel and cobalt concentrations of 8 Australian Portland cements ranged from 49 to 99|g/g, 5 to 54|g/g and < =1 to 13|g/g, respectively. The water-soluble chromate concentrations of the cements ranged from 0.2 to 8.1|g/g, and the sodium sulfate-extractable chromates form 1.4 to 9.7|g/g. Results for water-soluble nickel ( < =0.2|g/g) and cobalt ( < =0.05|g/g) indicate that the metals are present only as water-insoluble compounds. The significance of the various data is considered from a dermatological point of view. Cement extracts for the analysis of water-soluble hexavalent chromium (chromates) are stable for at least 12 days. The optimum extraction time for hexavalent chromium in cement appears to be 1h. Almost 100% reduction of hexavalent chromium is possible after 1h using 100 x the stoichiometric value of iron (II) sulfate. The chromates can become gradually insolubilised when the solution from the water added is in direct contact with the cement, i.e., over a period of > 60min to 7 days, even without the addition of iron (II) sulfate."
1516508,Tahedl and  Hader 1999,Fast examination of water quality using the automatic biotest ecotox based on the movement behavior of a freshwater flagellate,"BIOSIS COPYRIGHT: BIOL ABS. An early warning system, called ECOTOX, for monitoring the quality of water has been developed using different movement parameters of the motile unicellular flagellate Euglena gracilis as end points. The ability of orienting in the gravity field, the motility and the velocity of the cells were found to be sensitive to a number of toxic compounds. The biomonitor is controlled by a real time image analysis system which quantifies the movement parameters. Statistically significant changes in the measured parameters indicate a change in the tested water quality. The biomonitoring system works fully automatically and in a very short time. One cycle including a sample and control measurement takes between 6 to 10 min (depending on the software settings). For a number of toxins EC50 values have been calculated using the most sensitive end point, which is usually the gravitactic orientation. The toxic potential of a seepage water from an industrial waste deposit has been tested","Fast examination of water quality using the automatic biotest ecotox based on the movement behavior of a freshwater flagellate Abs: BIOSIS COPYRIGHT: BIOL ABS. An early warning system, called ECOTOX, for monitoring the quality of water has been developed using different movement parameters of the motile unicellular flagellate Euglena gracilis as end points. The ability of orienting in the gravity field, the motility and the velocity of the cells were found to be sensitive to a number of toxic compounds. The biomonitor is controlled by a real time image analysis system which quantifies the movement parameters. Statistically significant changes in the measured parameters indicate a change in the tested water quality. The biomonitoring system works fully automatically and in a very short time. One cycle including a sample and control measurement takes between 6 to 10 min (depending on the software settings). For a number of toxins EC50 values have been calculated using the most sensitive end point, which is usually the gravitactic orientation. The toxic potential of a seepage water from an industrial waste deposit has been tested"
1516507,Tabata 1969,The toxicity of heavy metals to aquatic animals and factors which decrease the toxicity. II. The antagonistic action of hardness components in water on the toxicity of heavy metal ions,"HEEP COPYRIGHT: BIOL ABS. A relationship between the Threshold Limit Maximum (TLM) of heavy metals (Cu-2+, Zn-2+, hexavalent Cr, Ni-2+, Co-2+, Cd-2+, Mn-2+ or Hg-2+) and water hardness was investigated. The heavy metal ions were kept completely dissolved. The TLM of the metal ions increased almost 2.8 plus or minus 0.6 fold when hardness increased 8 fold by addition of CaCl2 and MgSo4. There were exceptions to this relationship, but it could apply to Zn-2+, Cu-2+, Ni-2+, Co-2+ or Cd-2+. Japanese killifish, carp, Ctenopharyngodon, Pseudorasbora, rainbow trout and Daphnia were used as test animals. The toxicity of Hg-2+ or Mn-2+ was not affected by hardness. The toxicity of hexavalent Cr was affected in Daphnia but not in carp. The toxicity of concentrated heavy metals ions or heavy metal complexes might not be affected by hardness. Toxicity was affected slightly by Na+. The TIM of Zn-2+, Cu-2+, Cd-2+, Cu-2plus, Cd-2plus, Ni-2+ or Co-2+ increased 3-4 fold when hardness and Na ion in water increased 8 fold. Toxicity was not affected by K+ in natural fresh water.","The toxicity of heavy metals to aquatic animals and factors which decrease the toxicity. II. The antagonistic action of hardness components in water on the toxicity of heavy metal ions Abs: HEEP COPYRIGHT: BIOL ABS. A relationship between the Threshold Limit Maximum (TLM) of heavy metals (Cu-2+, Zn-2+, hexavalent Cr, Ni-2+, Co-2+, Cd-2+, Mn-2+ or Hg-2+) and water hardness was investigated. The heavy metal ions were kept completely dissolved. The TLM of the metal ions increased almost 2.8 plus or minus 0.6 fold when hardness increased 8 fold by addition of CaCl2 and MgSo4. There were exceptions to this relationship, but it could apply to Zn-2+, Cu-2+, Ni-2+, Co-2+ or Cd-2+. Japanese killifish, carp, Ctenopharyngodon, Pseudorasbora, rainbow trout and Daphnia were used as test animals. The toxicity of Hg-2+ or Mn-2+ was not affected by hardness. The toxicity of hexavalent Cr was affected in Daphnia but not in carp. The toxicity of concentrated heavy metals ions or heavy metal complexes might not be affected by hardness. Toxicity was affected slightly by Na+. The TIM of Zn-2+, Cu-2+, Cd-2+, Cu-2plus, Cd-2plus, Ni-2+ or Co-2+ increased 3-4 fold when hardness and Na ion in water increased 8 fold. Toxicity was not affected by K+ in natural fresh water."
1516505,Szarmach 1970,The most frequent contact allergens in the light of personal observations. AU - GOLEBIOWSKA-PODGORCZYK,"HEEP COPYRIGHT: BIOL ABS. Results of contact tests in workmen from various plants and branches of industry were analyzed closely. the investigations included 2725 men and 707 women with manifestations of contact eczema. Potassium dichromate, turpentine, paraphenylenediamine, nickel sulfate and cobalt chloride with the most frequent sensitizers. Colophony should also be classified with sensitizers inducing skin lesions. The general health of the patient plays an important role in contact eczema and contact dermatitis. The state of the epidermis alone is dependent on many internal factors. Working conditions, agents used for washing and cleaning the skin and the time of exposure to harmful agents also contribute to the occurrence of the disorders.","The most frequent contact allergens in the light of personal observations. AU - GOLEBIOWSKA-PODGORCZYK Abs: HEEP COPYRIGHT: BIOL ABS. Results of contact tests in workmen from various plants and branches of industry were analyzed closely. the investigations included 2725 men and 707 women with manifestations of contact eczema. Potassium dichromate, turpentine, paraphenylenediamine, nickel sulfate and cobalt chloride with the most frequent sensitizers. Colophony should also be classified with sensitizers inducing skin lesions. The general health of the patient plays an important role in contact eczema and contact dermatitis. The state of the epidermis alone is dependent on many internal factors. Working conditions, agents used for washing and cleaning the skin and the time of exposure to harmful agents also contribute to the occurrence of the disorders."
1516504,Szafnicki et al. 1998,Real-time supervision of industrial waste-water treatment plants applied to the surface treatment industries,"BIOSIS COPYRIGHT: BIOL ABS. The project described in this paper consists of two main stages: the development of a dedicated instrument enabling continuous simultaneous measures of industrial pollutants (e.g. metal ions: Ni2+, Cu2+, Zn2+,...) and the design of a Real-time Expert System (RTES) which would provide better information and decision support so as to improve the supervision of waste-water treatment plants in real-time, applied to the surface treatment (electroplating) industries. The sensor is based on the principle of spectral absorption analysis. The real-time expert system is being developed using a commercial, industrially validated RTES-development software G2 (by Gensym Corp.). A mixed knowledge-base is being implemented, comprising both types of knowledge: quantitative (e.g. theoretical knowledge issued from chemistry) and qualitative (i.e. operators' 'experience and know-how').","Real-time supervision of industrial waste-water treatment plants applied to the surface treatment industries Abs: BIOSIS COPYRIGHT: BIOL ABS. The project described in this paper consists of two main stages: the development of a dedicated instrument enabling continuous simultaneous measures of industrial pollutants (e.g. metal ions: Ni2+, Cu2+, Zn2+,...) and the design of a Real-time Expert System (RTES) which would provide better information and decision support so as to improve the supervision of waste-water treatment plants in real-time, applied to the surface treatment (electroplating) industries. The sensor is based on the principle of spectral absorption analysis. The real-time expert system is being developed using a commercial, industrially validated RTES-development software G2 (by Gensym Corp.). A mixed knowledge-base is being implemented, comprising both types of knowledge: quantitative (e.g. theoretical knowledge issued from chemistry) and qualitative (i.e. operators' 'experience and know-how')."
1516501,Sweet et al. 1999,Xenobiotic-induced apoptosis: Significance and potential application as a general biomarker of response,"BIOSIS COPYRIGHT: BIOL ABS. The process of apoptosis, often coined programmed cell death, involves cell injury induced by a variety of stimuli including xenobiotics and is morphologically, biochemically, and physiologically distinct from necrosis. Apoptotic death is characterized by cellular changes such as cytoplasm shrinkage, chromatin condensation, and plasma membrane asymmetry. This form of cell suicide is appealing as a general biomarker of response in that it is expressed in multiple cell systems (e.g. immune, neuron ormation on xenobiotic stress. Studies reviewed here suggest that apoptosis is a sensitive and earlyindicator of acute and chronic chemical stress, loss of cellular function and structure, and organismal health. Examples are provided of the application of this methodology in studies of health of lake trout (Salvelinus namaycush) in the Laurentian Great Lakes.","Xenobiotic-induced apoptosis: Significance and potential application as a general biomarker of response Abs: BIOSIS COPYRIGHT: BIOL ABS. The process of apoptosis, often coined programmed cell death, involves cell injury induced by a variety of stimuli including xenobiotics and is morphologically, biochemically, and physiologically distinct from necrosis. Apoptotic death is characterized by cellular changes such as cytoplasm shrinkage, chromatin condensation, and plasma membrane asymmetry. This form of cell suicide is appealing as a general biomarker of response in that it is expressed in multiple cell systems (e.g. immune, neuron ormation on xenobiotic stress. Studies reviewed here suggest that apoptosis is a sensitive and earlyindicator of acute and chronic chemical stress, loss of cellular function and structure, and organismal health. Examples are provided of the application of this methodology in studies of health of lake trout (Salvelinus namaycush) in the Laurentian Great Lakes."
1516499,Suter 1996,Toxicological benchmarks for screening contaminants of potential concern for effects on freshwater biota,"BIOSIS COPYRIGHT: BIOL ABS. An important early step in the assessment of ecological risks at contaminated sites is the screening of chemicals detected on the site to identify those that constitute a potential risk. Part of this screening process is the comparison of measured ambient concentrations to concentrations that are believed to be nonhazardous, termed ""benchmarks."" This article discusses 13 methods by which benchmarks may be derived for aquatic biota and presents benchmarks for 105 chemicals. It then compares them with respect to their sensitivity, availability, magnitude relative to background concentrations, and conceptual bases. Although some individual values can be shown to be too high to be protective and others are too low to be useful for screening, none of the approaches to benchmark derivation can be rejected without further definition of what constitutes adequate protection. The most appropriate screening strategy is to use multiple benchmark values along with background concent","Toxicological benchmarks for screening contaminants of potential concern for effects on freshwater biota Abs: BIOSIS COPYRIGHT: BIOL ABS. An important early step in the assessment of ecological risks at contaminated sites is the screening of chemicals detected on the site to identify those that constitute a potential risk. Part of this screening process is the comparison of measured ambient concentrations to concentrations that are believed to be nonhazardous, termed ""benchmarks."" This article discusses 13 methods by which benchmarks may be derived for aquatic biota and presents benchmarks for 105 chemicals. It then compares them with respect to their sensitivity, availability, magnitude relative to background concentrations, and conceptual bases. Although some individual values can be shown to be too high to be protective and others are too low to be useful for screening, none of the approaches to benchmark derivation can be rejected without further definition of what constitutes adequate protection. The most appropriate screening strategy is to use multiple benchmark values along with background concent"
1516497,Sulzbacher et al. 1997,Anaerobic reduction of hexavalent chromium in filter sludge of an electrochemical process,"BIOSIS COPYRIGHT: BIOL ABS. The potential of an anaerobic system to remediate hexavalent chromium containing waste was investigated. Experiments were performed at laboratory scale in the batch mode. The variables studied were the concentrations of waste, of inoculum, of yeast as an additional carbon source, of sulfate and the initial pH. The gas development, the final pH and the final concentrations of hexavalent and total chromium were measured. The evaluation was based on Multivariate data analysis. It could be shown that a remediation is possible. The influence of pH and sulfate were negligible in the given range. High yeast concentrations and low waste concentrations were favorable for a strong gas development and a complete elimination of chromate. Possible mechanisms are the active reduction of chromate by the microorganisms, its use as electron acceptor in bacterial respiration, and its sorption on organic material. Especially the last explanation is strongly supported by the experiments.","Anaerobic reduction of hexavalent chromium in filter sludge of an electrochemical process Abs: BIOSIS COPYRIGHT: BIOL ABS. The potential of an anaerobic system to remediate hexavalent chromium containing waste was investigated. Experiments were performed at laboratory scale in the batch mode. The variables studied were the concentrations of waste, of inoculum, of yeast as an additional carbon source, of sulfate and the initial pH. The gas development, the final pH and the final concentrations of hexavalent and total chromium were measured. The evaluation was based on Multivariate data analysis. It could be shown that a remediation is possible. The influence of pH and sulfate were negligible in the given range. High yeast concentrations and low waste concentrations were favorable for a strong gas development and a complete elimination of chromate. Possible mechanisms are the active reduction of chromate by the microorganisms, its use as electron acceptor in bacterial respiration, and its sorption on organic material. Especially the last explanation is strongly supported by the experiments."
1516495,Sudo and  Aiba 1973,Effect of copper and hexavalent chromium on the specific growth rate of Ciliata isolated from activated-sludge,"HEEP COPYRIGHT: BIOL ABS. After growing mass and monoxenic cultures of 3 species of Ciliata (Vorticella microstoma, Colpidium campylum and Opercularia sp.) with Alcaligenes faecalis as the sole protozoan food, and confirming that copper and hexavalent chromium did not affect the bacterial growth, the effect of these metals on the specific growth rate of each protozoa was examined. The term ILm (median inhibitory limit) was used to define the metal concentration required to reduce the specific growth rate of protozoa to 1/2 of that of a control. The ILm for copper was: 0.25 mg 1--1 (V. microstoma), 0.32 mg 1--1 (C. campylum), and 0.27 mg 1--1 (Opercularia sp.). Regarding hexavalent chromium, ILm for V. microstoma, C. campylum, and Opercularia sp. were 0.53, 12.9 and 20.2 mg 1--1, respectively. Acclimation of each protozoa to these metals for 96 h resulted in ILm enhanced values of 1.2-2.2 times as large as that for the control.","Effect of copper and hexavalent chromium on the specific growth rate of Ciliata isolated from activated-sludge Abs: HEEP COPYRIGHT: BIOL ABS. After growing mass and monoxenic cultures of 3 species of Ciliata (Vorticella microstoma, Colpidium campylum and Opercularia sp.) with Alcaligenes faecalis as the sole protozoan food, and confirming that copper and hexavalent chromium did not affect the bacterial growth, the effect of these metals on the specific growth rate of each protozoa was examined. The term ILm (median inhibitory limit) was used to define the metal concentration required to reduce the specific growth rate of protozoa to 1/2 of that of a control. The ILm for copper was: 0.25 mg 1--1 (V. microstoma), 0.32 mg 1--1 (C. campylum), and 0.27 mg 1--1 (Opercularia sp.). Regarding hexavalent chromium, ILm for V. microstoma, C. campylum, and Opercularia sp. were 0.53, 12.9 and 20.2 mg 1--1, respectively. Acclimation of each protozoa to these metals for 96 h resulted in ILm enhanced values of 1.2-2.2 times as large as that for the control."
1516492,Sturges et al. 1991,Performance of soil flushing and groundwater extraction at the United Chrome Superfund site,"BIOSIS COPYRIGHT: BIOL ABS. In 1987, CH2M HILL, under contract with the U.S. EPA, undertook the cleanup of the United Chrome Superfund site in Corvallis, Oregon. Waste disposal practices and leaky plating tanks at this chrome plating facility had resulted in heavy contamination of soil and groundwater by hexavalent chromium. Distinguishing elements of this site remediation project were two infiltration basins to flush contaminated soils, a 23-well groundwater extraction network in low permeability soils, and treatment of the concentrated chromium wastewaters. Remedial actions also included decontamination and demolition of structures, and offsite disposal of1,100 tons of contaminated soil and debris. The infiltration basins and groundwater extraction and treatment system have been operating since July 1988. This paper presents the data and experience gathered on the system's performance during the 2 years of operation, and points to potential application at other sites.","Performance of soil flushing and groundwater extraction at the United Chrome Superfund site Abs: BIOSIS COPYRIGHT: BIOL ABS. In 1987, CH2M HILL, under contract with the U.S. EPA, undertook the cleanup of the United Chrome Superfund site in Corvallis, Oregon. Waste disposal practices and leaky plating tanks at this chrome plating facility had resulted in heavy contamination of soil and groundwater by hexavalent chromium. Distinguishing elements of this site remediation project were two infiltration basins to flush contaminated soils, a 23-well groundwater extraction network in low permeability soils, and treatment of the concentrated chromium wastewaters. Remedial actions also included decontamination and demolition of structures, and offsite disposal of1,100 tons of contaminated soil and debris. The infiltration basins and groundwater extraction and treatment system have been operating since July 1988. This paper presents the data and experience gathered on the system's performance during the 2 years of operation, and points to potential application at other sites."
1516490,Stridsklev et al. 1994,Biologic monitoring of chromium and nickel among stainless steel welders using the Tungsten inert gas-method,"BIOSIS COPYRIGHT: BIOL ABS. Fourteen welders, welding stainless steel using the Tungsten Inert Gas method, were monitored for one work-week. During this time, measurements were taken for chromium (Cr), water soluble hexavalent Cr (CrVI), and nickel (Ni) in air, as well as Cr and Ni in the blood and urine of the welders. The welders provided a history of their previous exposure to Cr and Ni, their use of personal protective equipment, and their smoking habits. The CrVI in the air was generally below the detection level. Total Cr and Ni in air were frequently below the detection level, and generally below 10 mug/m3. The levels of Cr and Ni in blood were from below the detection levels to 1.0 mug. In the urine, levels were below 2.0 mug/g creatinine and 8.5 mug/g creatinine for Cr and Ni, respectively. Some welders had slightly elevated levels of total Cr in the urine that could result from bystander-exposure as derived from Manual Metal Arc welding performed in the same workplace.","Biologic monitoring of chromium and nickel among stainless steel welders using the Tungsten inert gas-method Abs: BIOSIS COPYRIGHT: BIOL ABS. Fourteen welders, welding stainless steel using the Tungsten Inert Gas method, were monitored for one work-week. During this time, measurements were taken for chromium (Cr), water soluble hexavalent Cr (CrVI), and nickel (Ni) in air, as well as Cr and Ni in the blood and urine of the welders. The welders provided a history of their previous exposure to Cr and Ni, their use of personal protective equipment, and their smoking habits. The CrVI in the air was generally below the detection level. Total Cr and Ni in air were frequently below the detection level, and generally below 10 mug/m3. The levels of Cr and Ni in blood were from below the detection levels to 1.0 mug. In the urine, levels were below 2.0 mug/g creatinine and 8.5 mug/g creatinine for Cr and Ni, respectively. Some welders had slightly elevated levels of total Cr in the urine that could result from bystander-exposure as derived from Manual Metal Arc welding performed in the same workplace."
1516488,Stollenwerk and  Grove 1985,"Adsorption and desorption of hexavalent chromium in an alluvial aquifer near Telluride, Colorado (USA)","HEEP COPYRIGHT: BIOL ABS. A laboratory investigation of reactions between Cr(VI) and alluvium was conducted to evaluate reactions of Cr(VI) contaminating an alluvial aquifer near Telluride, CO and to determine the mechanisms responsible for these reactions. Uncontaminated alluvium and groundwater (spiked with CrO42-) from the study site were used in batch and column experiments. Results of these experiments showed that Cr(VI) was adsorbed by the alluvium. Distribution coefficients from batch experiments ranged from 52 l/kg at an equilibrium CrO42- concentration of 0.4 mumol/l to 1.7 l/kg at an equilibrium concentration of 1400 mumol/l. The zero point of charge for the alluvium was 8.3, and the alluvium had a positive net charge at the groundwater pH of 6.8. Visual and chemical evidence indicated that Fe oxide and hydroxide coatings on the alluvial particles principally were responsible for the adsorption of Cr(VI). During column experiments, Cr(VI) initially was desorbed easily from the alluvium by Cr-fr 60 pore volumes of groundwater were required to decrease the effluent concentration of Cr(VI) to 3 mumol/l (drinking water standard for Cr(VI) = 1 mumol/l). The quantity of Cr(VI) adsorbed varied with the type and concentration of other anions in solution.","Adsorption and desorption of hexavalent chromium in an alluvial aquifer near Telluride, Colorado (USA) Abs: HEEP COPYRIGHT: BIOL ABS. A laboratory investigation of reactions between Cr(VI) and alluvium was conducted to evaluate reactions of Cr(VI) contaminating an alluvial aquifer near Telluride, CO and to determine the mechanisms responsible for these reactions. Uncontaminated alluvium and groundwater (spiked with CrO42-) from the study site were used in batch and column experiments. Results of these experiments showed that Cr(VI) was adsorbed by the alluvium. Distribution coefficients from batch experiments ranged from 52 l/kg at an equilibrium CrO42- concentration of 0.4 mumol/l to 1.7 l/kg at an equilibrium concentration of 1400 mumol/l. The zero point of charge for the alluvium was 8.3, and the alluvium had a positive net charge at the groundwater pH of 6.8. Visual and chemical evidence indicated that Fe oxide and hydroxide coatings on the alluvial particles principally were responsible for the adsorption of Cr(VI). During column experiments, Cr(VI) initially was desorbed easily from the alluvium by Cr-fr 60 pore volumes of groundwater were required to decrease the effluent concentration of Cr(VI) to 3 mumol/l (drinking water standard for Cr(VI) = 1 mumol/l). The quantity of Cr(VI) adsorbed varied with the type and concentration of other anions in solution."
1516487,Stollenwerk and  Grove 1985,Reduction of hexavalent chromium in water samples acidified for preservation,Biosis copyright: biol abs. rrm water pollution metal pollution,Reduction of hexavalent chromium in water samples acidified for preservation Abs: Biosis copyright: biol abs. rrm water pollution metal pollution
1516486,Stoll and  Duncan 1996,"Enhanced heavy metal removal from waste water by viable, glucose pretreated Saccharomyces cerevisiae cells","BIOSIS COPYRIGHT: BIOL ABS. The bioaccumulation of metals (Cu2+, Cr6+, Cd2+, Ni2+ and Zn2+) from three electroplating effluents by viable Saccharomyces cerevisiae, and the effect of glucose treatment on accumulation was determined. Pretreatment of the yeast cells with glucose increased the amount of metal removed, whilst direct addition of glucose to the yeast-effluent solution had no effect on the amount of metal accumulated.","Enhanced heavy metal removal from waste water by viable, glucose pretreated Saccharomyces cerevisiae cells Abs: BIOSIS COPYRIGHT: BIOL ABS. The bioaccumulation of metals (Cu2+, Cr6+, Cd2+, Ni2+ and Zn2+) from three electroplating effluents by viable Saccharomyces cerevisiae, and the effect of glucose treatment on accumulation was determined. Pretreatment of the yeast cells with glucose increased the amount of metal removed, whilst direct addition of glucose to the yeast-effluent solution had no effect on the amount of metal accumulated."
1516485,St-Laurent et al. 1992,Comparative assessment of herbicide phytotoxicity to Selenastrum capricornutum using microplate and flask bioassay procedures,"BIOSIS COPYRIGHT: BIOL ABS. Four reference toxicants (Cr6+, Cu2+, Zn2+, phenol) and 9 herbicides (imazamethabenz, 2,4-dichlorophenoxyacetic acid, picloram, glyphosate, bromoxynil, metolachlor, diquat dibromide, hexazinone, cyanazine) were appraised using both the microplate and flask assay. Ninety-six hour EC50s determined with Selenastrum capricornutum as the indicator species essentially demonstrated good intermethodological data concordance for all chemicals, with the exception of diquat dibromide, whose phytotoxicity in the microplate assay (EC50 = 4.9 mug2 mugerature relating to similar herbicides with the same or different green algal indicator species appeared to corroborate the overall data obtained in our study. More than 4 orders of magnitude separated the most toxic (cyanazine, flask, and microplate EC50s of 17.6 and 16.9 mugoxic (imazamethabenz, flask, and microplate EC50s of 89.1 and 91.1 mgoxicity comparison described in this work suggests that the simpler algal microplate assay can b","Comparative assessment of herbicide phytotoxicity to Selenastrum capricornutum using microplate and flask bioassay procedures Abs: BIOSIS COPYRIGHT: BIOL ABS. Four reference toxicants (Cr6+, Cu2+, Zn2+, phenol) and 9 herbicides (imazamethabenz, 2,4-dichlorophenoxyacetic acid, picloram, glyphosate, bromoxynil, metolachlor, diquat dibromide, hexazinone, cyanazine) were appraised using both the microplate and flask assay. Ninety-six hour EC50s determined with Selenastrum capricornutum as the indicator species essentially demonstrated good intermethodological data concordance for all chemicals, with the exception of diquat dibromide, whose phytotoxicity in the microplate assay (EC50 = 4.9 mug2 mugerature relating to similar herbicides with the same or different green algal indicator species appeared to corroborate the overall data obtained in our study. More than 4 orders of magnitude separated the most toxic (cyanazine, flask, and microplate EC50s of 17.6 and 16.9 mugoxic (imazamethabenz, flask, and microplate EC50s of 89.1 and 91.1 mgoxicity comparison described in this work suggests that the simpler algal microplate assay can b"
1516482,Stern et al. 1985,Cr(VI) and Other Metallic Mutagens in Fly Ash and Welding Fumes,"The occurrence of hexavalent chromium (18540299) (Cr(VI)) compounds and other metallic mutagens in fly ash and welding fumes is discussed. Studies on fly ash and welding fume samples show extreme sensitivity of the analytical methods to the details of collection, storage, and chemical and biological assays. For example, the concentrations of Cr(VI) found by random analyses of aged samples of coal fly ash, 0.5 to 2.0 parts per million water soluble Cr(VI), if present in the original sample could account for much of the mutagenic activity of the samples. The presence of divalent iron (15438310) compounds in fly ash suggests that significant reduction of Cr(VI) to trivalent chromium (16065831) may have occurred, so that the measured Cr(VI) concentrations must be regarded as lower limits only. Analyses of welding fumes have shown the presence of chromium (7440473) and nickel (7440020) which behave biologically in an identical way to chromium and nickel obtained from other sources. There is evidence that Cr(VI) in welding fumes collected on paper filters and stored at room temperature is not stable. A relatively stable Cr(VI) fraction is apparently formed when aqueous impingers are used; however, the solubility of chromium species depends to a great extent on the impinger medium chosen and the pH maintained on the impinger during collection. Fly ash and welding fumes contain a large number of trace metals in addition to chromium and nickel, such as vanadium (7440622), lead (7439921), zinc (7440666), and copper (7440508). Studies of the properties of these must be linked with studies which aim at evaluating the risk of environmental or occupational exposure. It is noted that almost all metallic elements are genotoxic in some form in some short term bioassay. The variation in characteristic and biological properties of metallic aerosols raises serious questions concerning the interpretation of bioassay results.","Cr(VI) and Other Metallic Mutagens in Fly Ash and Welding Fumes Abs: The occurrence of hexavalent chromium (18540299) (Cr(VI)) compounds and other metallic mutagens in fly ash and welding fumes is discussed. Studies on fly ash and welding fume samples show extreme sensitivity of the analytical methods to the details of collection, storage, and chemical and biological assays. For example, the concentrations of Cr(VI) found by random analyses of aged samples of coal fly ash, 0.5 to 2.0 parts per million water soluble Cr(VI), if present in the original sample could account for much of the mutagenic activity of the samples. The presence of divalent iron (15438310) compounds in fly ash suggests that significant reduction of Cr(VI) to trivalent chromium (16065831) may have occurred, so that the measured Cr(VI) concentrations must be regarded as lower limits only. Analyses of welding fumes have shown the presence of chromium (7440473) and nickel (7440020) which behave biologically in an identical way to chromium and nickel obtained from other sources. There is evidence that Cr(VI) in welding fumes collected on paper filters and stored at room temperature is not stable. A relatively stable Cr(VI) fraction is apparently formed when aqueous impingers are used; however, the solubility of chromium species depends to a great extent on the impinger medium chosen and the pH maintained on the impinger during collection. Fly ash and welding fumes contain a large number of trace metals in addition to chromium and nickel, such as vanadium (7440622), lead (7439921), zinc (7440666), and copper (7440508). Studies of the properties of these must be linked with studies which aim at evaluating the risk of environmental or occupational exposure. It is noted that almost all metallic elements are genotoxic in some form in some short term bioassay. The variation in characteristic and biological properties of metallic aerosols raises serious questions concerning the interpretation of bioassay results."
1516481,Stern et al. 1984,Chromium vi and other metallic mutagens in fly ash and welding fumes,Heep copyright: biol abs. rrm human cancer geno toxicity,Chromium vi and other metallic mutagens in fly ash and welding fumes Abs: Heep copyright: biol abs. rrm human cancer geno toxicity
1516480,Stern et al. 1984,Cr(VI) and other metallic mutagens in fly ash and welding fumes,"A review. Particulate samples taken from both the indoor (working) and outdoor (community) environments contain a wide range of metallic trade elements, most of which are mutagenic in at least one of the short-term tests for genotoxicity currently in use. Because of the demonstrated presence of hexavalent chromium (Cr(VI)), which is short-lived, and the uncertainty with which screening tests can be interpreted in terms of human risk, collection, storage and analysis of samples must be done carefully with appropriate methods. The sensitivity of results to variations in sampling and analysis protocols is demonstrated and discussed.","Cr(VI) and other metallic mutagens in fly ash and welding fumes Abs: A review. Particulate samples taken from both the indoor (working) and outdoor (community) environments contain a wide range of metallic trade elements, most of which are mutagenic in at least one of the short-term tests for genotoxicity currently in use. Because of the demonstrated presence of hexavalent chromium (Cr(VI)), which is short-lived, and the uncertainty with which screening tests can be interpreted in terms of human risk, collection, storage and analysis of samples must be done carefully with appropriate methods. The sensitivity of results to variations in sampling and analysis protocols is demonstrated and discussed."
1516473,Stephenson 1982,"Health Hazard Evaluation Report, No. HETA-81-283-1224, Southern Minnesota Beet Sugar Cooperative, Renville, Minnesota","Exposures to chemicals used during beet sugar processing and to welding fumes were investigated on August 25 to 27, 1981 and February 17 to 19, 1982 at Southern Minnesota Beet Sugar cooperative (SIC-2063), Renville, Minnesota. Evaluation was requested by a representative of the American Federation of Grain Millers, Local 369, for an unspecified number of workers. Long term personal and area air samples were analyzed; 15 workers completed medical questionnaires. Concentrations of hexavalent-chromium (18540299) and nickel (7440020) exceeded respective NIOSH limits of 1.0 micrograms per cubic meter and 0.015 milligrams per cubic meter (mg/m3). Concentrations of calcium-oxide (1306190) exceeded the OSHA standard of 5mg/m3; no NIOSH standard exists. No exposure hazards were found for bis-chloromethyl-ether (542881), formaldehyde (50000), hydrochloric-acid (7647010), sulfur-dioxide (7446095), carbon-dioxide (124389), chromium (7440473), fluoride (16984488), fumes from iron-oxide (1309371), manganese (7439965) or copper (7440508). Workers reported symptoms of skin and eye irritations and skin burns. The author concludes that exposure hazards exist for hexavalent-chromium, nickel, and calcium-oxide, and suggests that a hazard from ultraviolet radiation may exist during welding operations. He recommends engineering controls, protective clothing, exposure warning systems, education and health programs.","Health Hazard Evaluation Report, No. HETA-81-283-1224, Southern Minnesota Beet Sugar Cooperative, Renville, Minnesota Abs: Exposures to chemicals used during beet sugar processing and to welding fumes were investigated on August 25 to 27, 1981 and February 17 to 19, 1982 at Southern Minnesota Beet Sugar cooperative (SIC-2063), Renville, Minnesota. Evaluation was requested by a representative of the American Federation of Grain Millers, Local 369, for an unspecified number of workers. Long term personal and area air samples were analyzed; 15 workers completed medical questionnaires. Concentrations of hexavalent-chromium (18540299) and nickel (7440020) exceeded respective NIOSH limits of 1.0 micrograms per cubic meter and 0.015 milligrams per cubic meter (mg/m3). Concentrations of calcium-oxide (1306190) exceeded the OSHA standard of 5mg/m3; no NIOSH standard exists. No exposure hazards were found for bis-chloromethyl-ether (542881), formaldehyde (50000), hydrochloric-acid (7647010), sulfur-dioxide (7446095), carbon-dioxide (124389), chromium (7440473), fluoride (16984488), fumes from iron-oxide (1309371), manganese (7439965) or copper (7440508). Workers reported symptoms of skin and eye irritations and skin burns. The author concludes that exposure hazards exist for hexavalent-chromium, nickel, and calcium-oxide, and suggests that a hazard from ultraviolet radiation may exist during welding operations. He recommends engineering controls, protective clothing, exposure warning systems, education and health programs."
1516472,Stephen and  Macnaughton 1999,Developments in terrestrial bacterial remediation of metals,Biosis copyright: biol abs. rrm journal article bacteria bioremediating agent bioprocess engineering methodology terrestrial ecology terrestrial bacterial metal remediation toxic metal remediation radionuclide-contaminated terrestrial environment bioremediation method contaminant removal method remediation method,Developments in terrestrial bacterial remediation of metals Abs: Biosis copyright: biol abs. rrm journal article bacteria bioremediating agent bioprocess engineering methodology terrestrial ecology terrestrial bacterial metal remediation toxic metal remediation radionuclide-contaminated terrestrial environment bioremediation method contaminant removal method remediation method
1516468,Stackhouse and  Benson 1988,The influence of humic acid on the toxicity and bioavailability of selected trace metals,Biosis copyright: biol abs. rrm daphnia-pulex heavy metal toxicity chromium cadmium drilling fluid disposal,The influence of humic acid on the toxicity and bioavailability of selected trace metals Abs: Biosis copyright: biol abs. rrm daphnia-pulex heavy metal toxicity chromium cadmium drilling fluid disposal
1516467,Srivastava et al. 1989,Adsorption of heavy metal ions on carbonaceous material developed from the waste slurry generated in local fertilizer plants,Biosis copyright: biol abs. rrm activated carbon recycling waste management,Adsorption of heavy metal ions on carbonaceous material developed from the waste slurry generated in local fertilizer plants Abs: Biosis copyright: biol abs. rrm activated carbon recycling waste management
1516466,Srivastava et al. 1985,Estimation of chromium-vi in water tannery and plating wastes,Biosis copyright: biol abs. rrm,Estimation of chromium-vi in water tannery and plating wastes Abs: Biosis copyright: biol abs. rrm
1516465,Srinivasan et al. 1988,Studies on chromium removal by rice husk carbon,Biosis copyright: biol abs. rrm waste water water supply treatment pollution control,Studies on chromium removal by rice husk carbon Abs: Biosis copyright: biol abs. rrm waste water water supply treatment pollution control
1516464,Spottswood 1981,"In-Depth Survey Report of Greensboro Industrial Plating, Greensboro, North Carolina","An indepth control technology survey was conducted at Greensboro Industrial Plating (SIC-3471), Greensboro, North Carolina in January 1981 and November 1981. The survey was conducted to assess occupational health problems through the application of control technology. Air samples were collected and analyzed for hexavalent-chromium (18540299) (CrVI) and sulfuric-acid (7664939). Ventilation measurements were taken. Employee exposures to CrVI ranged from 0.001 to 0.014 milligrams per cubic meter (mg/m3) for an 8 hour time weighted average (TWA). The mean exposure for the three workers was 0.004mg/m3 compared with the OSHA permissible exposure limit (PEL) of 0.100mg/m3 for an 8 hour TWA. NIOSH recommended limit for CrVI was 0.025mg/m3 for an 8 hour TWA. For sulfuric-acid, exposures ranged between 0.107 and 0.967mg/m3 with a mean of 0.327mg/m3 for an 8 hour TWA, compared with OSHA PEL of 1.0mg/m3. Double sided draft ventilation hoods and three sided hoods were used for contaminant control, the former being more effective. Recommended exhaust rate was 250 cubic feet per minute per square foot. Only one of the tanks approached that rate. The author concludes that employee exposures are within OSHA and NIOSH recommendations. Higher exhaust rates may be required for higher production rates.","In-Depth Survey Report of Greensboro Industrial Plating, Greensboro, North Carolina Abs: An indepth control technology survey was conducted at Greensboro Industrial Plating (SIC-3471), Greensboro, North Carolina in January 1981 and November 1981. The survey was conducted to assess occupational health problems through the application of control technology. Air samples were collected and analyzed for hexavalent-chromium (18540299) (CrVI) and sulfuric-acid (7664939). Ventilation measurements were taken. Employee exposures to CrVI ranged from 0.001 to 0.014 milligrams per cubic meter (mg/m3) for an 8 hour time weighted average (TWA). The mean exposure for the three workers was 0.004mg/m3 compared with the OSHA permissible exposure limit (PEL) of 0.100mg/m3 for an 8 hour TWA. NIOSH recommended limit for CrVI was 0.025mg/m3 for an 8 hour TWA. For sulfuric-acid, exposures ranged between 0.107 and 0.967mg/m3 with a mean of 0.327mg/m3 for an 8 hour TWA, compared with OSHA PEL of 1.0mg/m3. Double sided draft ventilation hoods and three sided hoods were used for contaminant control, the former being more effective. Recommended exhaust rate was 250 cubic feet per minute per square foot. Only one of the tanks approached that rate. The author concludes that employee exposures are within OSHA and NIOSH recommendations. Higher exhaust rates may be required for higher production rates."
1516463,Spottswood 1981,"In-Depth Survey Report of Electro-Coatings, Houston, Texas","An indepth survey of control technology was conducted at Electro Coatings (SIC-3471) in Houston, Texas, on August 11 to 13, 1981. The survey was conducted as part of a NIOSH assessment of engineering control technology in electroplating operations. Personal, tank, and area samples were taken for hexavalent-chromium (18540299) (Cr-VI), and sulfuric-acid (7664939) for 3 consecutive days. Total chromium (7440473) (Cr) was collected. Area and tank sampling for Cr-VI and Cr were well within OSHA limits for an 8 hour period. Personal exposures were also below OSHA limits and were 25 percent of the NIOSH recommended standards. For sulfuric-acid, exposures were 5 percent of the OSHA limit and the NIOSH recommended concentration. Employees wore gloves during plating operations and washed their hands frequently during manual operations. The author concludes that the effective control of tank contaminants is due to good local exhaust ventilation and good work practices. The facility has demonstrated that safe and healthful working environments can be achieved within electroplating operations with the use of effective engineering control technology, good work practices, and effective management.","In-Depth Survey Report of Electro-Coatings, Houston, Texas Abs: An indepth survey of control technology was conducted at Electro Coatings (SIC-3471) in Houston, Texas, on August 11 to 13, 1981. The survey was conducted as part of a NIOSH assessment of engineering control technology in electroplating operations. Personal, tank, and area samples were taken for hexavalent-chromium (18540299) (Cr-VI), and sulfuric-acid (7664939) for 3 consecutive days. Total chromium (7440473) (Cr) was collected. Area and tank sampling for Cr-VI and Cr were well within OSHA limits for an 8 hour period. Personal exposures were also below OSHA limits and were 25 percent of the NIOSH recommended standards. For sulfuric-acid, exposures were 5 percent of the OSHA limit and the NIOSH recommended concentration. Employees wore gloves during plating operations and washed their hands frequently during manual operations. The author concludes that the effective control of tank contaminants is due to good local exhaust ventilation and good work practices. The facility has demonstrated that safe and healthful working environments can be achieved within electroplating operations with the use of effective engineering control technology, good work practices, and effective management."
1516462,Sperling et al. 1992,Determination of chromium(III) and chromium(VI) in water using flow injection on-line preconcentration with selective adsorption on activated alumina and flame atomic absorption spectrometric detection,"BIOSIS COPYRIGHT: BIOL ABS. A rapid and sensitive method for the species-selective determination of chromium(III) and chromium(VI) in water samples by flame atomic absorption spectrometry using on-line preconcentration on a microcolumn packed with activated alumina (acidic form) has been developed. Sequential species-selective sorption was possible by using the Clark-Lubs buffer systems with pH 7 for Cr(III) and pH 2 for Cr(VI). The preconcentrated species were eluted directly from the column to the nebulizer-burner system using 1.0 mol nitric acid and 0.5 mol/L ammonia for Cr(III) and Cr(VI), respectively. The retention efficiency was better than 80% for Cr(III) and better than 90% for Cr(VI), giving a sensitivity enhancement of 25 for a 3-mL sample loading. The effect of concomitant species was investigated, and satisfactory recovery of 90-106% could be obtained from natural water samples. Linear calibration for both species was established over the concentration range 10-200 mug/L with detection","Determination of chromium(III) and chromium(VI) in water using flow injection on-line preconcentration with selective adsorption on activated alumina and flame atomic absorption spectrometric detection Abs: BIOSIS COPYRIGHT: BIOL ABS. A rapid and sensitive method for the species-selective determination of chromium(III) and chromium(VI) in water samples by flame atomic absorption spectrometry using on-line preconcentration on a microcolumn packed with activated alumina (acidic form) has been developed. Sequential species-selective sorption was possible by using the Clark-Lubs buffer systems with pH 7 for Cr(III) and pH 2 for Cr(VI). The preconcentrated species were eluted directly from the column to the nebulizer-burner system using 1.0 mol nitric acid and 0.5 mol/L ammonia for Cr(III) and Cr(VI), respectively. The retention efficiency was better than 80% for Cr(III) and better than 90% for Cr(VI), giving a sensitivity enhancement of 25 for a 3-mL sample loading. The effect of concomitant species was investigated, and satisfactory recovery of 90-106% could be obtained from natural water samples. Linear calibration for both species was established over the concentration range 10-200 mug/L with detection"
1516461,Soudel et al. 1998,Bioaccumulation of heavy metals by hair-root cultures of Armoracia rusticana L. (I.),"BIOSIS COPYRIGHT: BIOL ABS. Tissue cultures of Armoracia rusticana L., both transformed with Agrobacterium rhizogenes. Bioaccumulation of heavy metals by hairy-root culture was studied. The highest accumulation rate was found for Hg2+, Fe2+, Fe3+ and Cu2+.","Bioaccumulation of heavy metals by hair-root cultures of Armoracia rusticana L. (I.) Abs: BIOSIS COPYRIGHT: BIOL ABS. Tissue cultures of Armoracia rusticana L., both transformed with Agrobacterium rhizogenes. Bioaccumulation of heavy metals by hairy-root culture was studied. The highest accumulation rate was found for Hg2+, Fe2+, Fe3+ and Cu2+."
1516460,Sorahan et al. 1998,Quantitative risk assessments derived from occupational cancer epidemiology a worked example,Biosis copyright: biol abs. rrm journal article human human worker patient occupational health pollution quantitative risk assessments hexavalent chromium exposure levels pollutant cumulative exposure carcinogen tumor biology occupational cancer epidemiology risk coefficients epidemiology,Quantitative risk assessments derived from occupational cancer epidemiology a worked example Abs: Biosis copyright: biol abs. rrm journal article human human worker patient occupational health pollution quantitative risk assessments hexavalent chromium exposure levels pollutant cumulative exposure carcinogen tumor biology occupational cancer epidemiology risk coefficients epidemiology
1516458,Soni and  Abbasi 1981,"Mortality and reproduction in earthworms, Pheretima posthuma, exposed to chromium(VI)","HEEP COPYRIGHT: BIOL ABS. Earthworms, P. posthuma, were exposed to Cr(VI) levels varying from 0-100 ppm in 3 sets of experiments. In 2 sets the time required for 100% mortality decreased with increase in Cr concentration, but no trends were observed relating intermediate ( < 100%) mortality to toxin concentration or time of exposure. The incidence of sexual reproduction and regeneration was higher in Cr-treated media compared to controls. Attempts to use tannery effluents for irrigation will be harmful to the soil environment, even if the effluents are diluted 7 times before use.","Mortality and reproduction in earthworms, Pheretima posthuma, exposed to chromium(VI) Abs: HEEP COPYRIGHT: BIOL ABS. Earthworms, P. posthuma, were exposed to Cr(VI) levels varying from 0-100 ppm in 3 sets of experiments. In 2 sets the time required for 100% mortality decreased with increase in Cr concentration, but no trends were observed relating intermediate ( < 100%) mortality to toxin concentration or time of exposure. The incidence of sexual reproduction and regeneration was higher in Cr-treated media compared to controls. Attempts to use tannery effluents for irrigation will be harmful to the soil environment, even if the effluents are diluted 7 times before use."
1516457,Song et al. 1998,Influence of electron donor and toxic materials on the activity of sulfate reducing bacteria for the treatment of electroplating wastewater,"BIOSIS COPYRIGHT: BIOL ABS. The effects of electron donor and toxic materials on the activity of SRB (sulfate reducing bacteria) were evaluated to ensure the efficient treatment of electroplating wastewater using an anaerobic batch test. The maximum utilization rate of glucose by SRB was slightly slower than that of lactate and acetate, but the affinity of glucose on the SRB was similar to that of the acetate and the lactate. The concentration of carbon source required to reduce 2,000mg of sulfate. that is the common concentration of sulfate in the raw electroplating wastewater, was estimated as about 2,200mg COD/L. The efficiency of carbon source for the reduction of sulfate was the highest at around 0.33 of the COD/SO4-2 ratio, but the rate of sulfate reduction was increased according to the increase of COD/SO4-2 ratio ranged from 0.18 to 1.21. Inhibition of copper on the activity of SRB was able to explain using non-competitive inhibition model, and IC50 for copper, that is the concentration cau","Influence of electron donor and toxic materials on the activity of sulfate reducing bacteria for the treatment of electroplating wastewater Abs: BIOSIS COPYRIGHT: BIOL ABS. The effects of electron donor and toxic materials on the activity of SRB (sulfate reducing bacteria) were evaluated to ensure the efficient treatment of electroplating wastewater using an anaerobic batch test. The maximum utilization rate of glucose by SRB was slightly slower than that of lactate and acetate, but the affinity of glucose on the SRB was similar to that of the acetate and the lactate. The concentration of carbon source required to reduce 2,000mg of sulfate. that is the common concentration of sulfate in the raw electroplating wastewater, was estimated as about 2,200mg COD/L. The efficiency of carbon source for the reduction of sulfate was the highest at around 0.33 of the COD/SO4-2 ratio, but the rate of sulfate reduction was increased according to the increase of COD/SO4-2 ratio ranged from 0.18 to 1.21. Inhibition of copper on the activity of SRB was able to explain using non-competitive inhibition model, and IC50 for copper, that is the concentration cau"
1516455,Snider ,"Installation restoration program phase i - whiteman afb, missouri","HMTC Phase I of this DOD installation restoration program (IRP) is a record search to determine the potential for off-base emigration of toxic or hazardous wastes from past operations and disposal activities at Whiteman Air Force Base. Results from field inspections, record searches, and base personnel interviews show that six sites (chlordane application areas, fire protection training area, landfill, excess pesticide disposal area, sodium chromate treatment area, and drum storage areas) have the potential to contaminate the environment. Geological maps and contamination tables are included. Recommendations for follow-up investigations are contained in Phase II of the IRP.","Installation restoration program phase i - whiteman afb, missouri Abs: HMTC Phase I of this DOD installation restoration program (IRP) is a record search to determine the potential for off-base emigration of toxic or hazardous wastes from past operations and disposal activities at Whiteman Air Force Base. Results from field inspections, record searches, and base personnel interviews show that six sites (chlordane application areas, fire protection training area, landfill, excess pesticide disposal area, sodium chromate treatment area, and drum storage areas) have the potential to contaminate the environment. Geological maps and contamination tables are included. Recommendations for follow-up investigations are contained in Phase II of the IRP."
1516453,Skripkin Yu et al. 1974,Occupational Allergic Dermatoses in Electroplaters,"Skin tests were performed in 225 workers employed at several electroplating shops, who were affected by dermatitis and eczema due to exposure to galvanic solutions of chromic-anhydride, ammonium-bichromate, nickel-sulfate (7786814) and chromium-oxide (1308389). A total of 79 percent of the workers tested showed definite sensitization reactions to chromium (7440473) and nickel (7440020) salts. Immunological tests showed the presence of autoantibodies in 21 of 67 patients with recurring allergic dermatitis and eczema. Tests were also performed in dermatitis patients employed in the gold (7440575) plating industry. Strict preventive measures and careful preemployment testing before hiring new workers are recommended. (Russian; English translation available)","Occupational Allergic Dermatoses in Electroplaters Abs: Skin tests were performed in 225 workers employed at several electroplating shops, who were affected by dermatitis and eczema due to exposure to galvanic solutions of chromic-anhydride, ammonium-bichromate, nickel-sulfate (7786814) and chromium-oxide (1308389). A total of 79 percent of the workers tested showed definite sensitization reactions to chromium (7440473) and nickel (7440020) salts. Immunological tests showed the presence of autoantibodies in 21 of 67 patients with recurring allergic dermatitis and eczema. Tests were also performed in dermatitis patients employed in the gold (7440575) plating industry. Strict preventive measures and careful preemployment testing before hiring new workers are recommended. (Russian; English translation available)"
1516451,Sisti et al. 1996,Reduction of dichromate by Thiobacillus ferrooxidans,"BIOSIS COPYRIGHT: BIOL ABS. Chromium(VI) was reduced by Thiobacillus ferrooxidans grown with elemental sulphur as the sole energy source. Chromium(VI) reduction (as high as 2000 muM), was due to the presence of sulphite and thiosulphate, among others with high reducing power which was generated during the sulphur oxidation by the bacteria. Therefore, Thiobacillus ferrooxidans could be used to treat chromium(VI)-containing industrial effluents.","Reduction of dichromate by Thiobacillus ferrooxidans Abs: BIOSIS COPYRIGHT: BIOL ABS. Chromium(VI) was reduced by Thiobacillus ferrooxidans grown with elemental sulphur as the sole energy source. Chromium(VI) reduction (as high as 2000 muM), was due to the presence of sulphite and thiosulphate, among others with high reducing power which was generated during the sulphur oxidation by the bacteria. Therefore, Thiobacillus ferrooxidans could be used to treat chromium(VI)-containing industrial effluents."
1516450,Singh and  Tiwari 1997,Removal and recovery of chromium(VI) from industrial waste water,"BIOSIS COPYRIGHT: BIOL ABS. Carbon slurry, generated as a waste material in a naphtha-based ammonia plant of the Fertilizer Corporation of India, Gorakhpur, has been used as an adsorbent for the removal of Cr(VI) from aqueous solution at different experimental conditions. The removal was favoured at low pH, with maximum removal at pH 2.5. The effects of concentration and temperature have also been reported. Batch adsorption kinetics have been described by the Lagergren equation. The applicability of the Langmuir isotherm for the present system has been tested at different temperatures. Thermodynamic parameters indicate the endothermic nature of Cr(VI) adsorption on carbon slurry. Recovery of adsorbed chromium for reuse has also been reported in the present study.","Removal and recovery of chromium(VI) from industrial waste water Abs: BIOSIS COPYRIGHT: BIOL ABS. Carbon slurry, generated as a waste material in a naphtha-based ammonia plant of the Fertilizer Corporation of India, Gorakhpur, has been used as an adsorbent for the removal of Cr(VI) from aqueous solution at different experimental conditions. The removal was favoured at low pH, with maximum removal at pH 2.5. The effects of concentration and temperature have also been reported. Batch adsorption kinetics have been described by the Lagergren equation. The applicability of the Langmuir isotherm for the present system has been tested at different temperatures. Thermodynamic parameters indicate the endothermic nature of Cr(VI) adsorption on carbon slurry. Recovery of adsorbed chromium for reuse has also been reported in the present study."
1516449,Singh and  Lal 1992,Removal of chromium(VI) from aqueous solutions using waste tea leaves carbon,BIOSIS COPYRIGHT: BIOL ABS. The waste tea leaves have been converted into cheap carbonaceous adsorbent material by sulfuric acid treatment. This product exhibits a good adsorption potential for chromium (VI) with a peak value at pHate that Cr2O72- is the major Cr(VI) species involved in surface association of tea leaves carbon (TLC). Some column studies have been performed with a view of removal/recovery of Cr(VI) and chemical regeneration of the adsorbent material. The breakthrough capacity was found to be 39.3 mg/g for Cr(VI). The column packed with developed carbon has been reported to remove Cr(VI) from the waste effluent of the chromium plating shop.,Removal of chromium(VI) from aqueous solutions using waste tea leaves carbon Abs: BIOSIS COPYRIGHT: BIOL ABS. The waste tea leaves have been converted into cheap carbonaceous adsorbent material by sulfuric acid treatment. This product exhibits a good adsorption potential for chromium (VI) with a peak value at pHate that Cr2O72- is the major Cr(VI) species involved in surface association of tea leaves carbon (TLC). Some column studies have been performed with a view of removal/recovery of Cr(VI) and chemical regeneration of the adsorbent material. The breakthrough capacity was found to be 39.3 mg/g for Cr(VI). The column packed with developed carbon has been reported to remove Cr(VI) from the waste effluent of the chromium plating shop.
1516448,Singh et al. 1992,Studies on the removal of chromium(VI) from waste-water by feldspar,"BIOSIS COPYRIGHT: BIOL ABS. The efficacy of feldspar in the removal of Cr(VI) from representative waste-water from a plating industry has been investigated in a completely mixed batch reactor at different concentrations, rate of agitation and particle size. The data obey the Langmuir isotherm for the present system and the process of uptake follows first-order kinetics. The maximum removal (91%) was observed at 40ê C and pH 2.5 with initial concentration of 19.23 mumol dm-3 C(VI) and 40 g dm-3 feldspar. The process involves both film and pore diffusion to different extents. Column studies have also been carried out using a certain concentration of waste-water. More than 92% recovery has been achieved and the column can be used for 10 cycles before regeneration. The present technique seems to be quite attractive.","Studies on the removal of chromium(VI) from waste-water by feldspar Abs: BIOSIS COPYRIGHT: BIOL ABS. The efficacy of feldspar in the removal of Cr(VI) from representative waste-water from a plating industry has been investigated in a completely mixed batch reactor at different concentrations, rate of agitation and particle size. The data obey the Langmuir isotherm for the present system and the process of uptake follows first-order kinetics. The maximum removal (91%) was observed at 40ê C and pH 2.5 with initial concentration of 19.23 mumol dm-3 C(VI) and 40 g dm-3 feldspar. The process involves both film and pore diffusion to different extents. Column studies have also been carried out using a certain concentration of waste-water. More than 92% recovery has been achieved and the column can be used for 10 cycles before regeneration. The present technique seems to be quite attractive."
1516445,Sims et al. 1984,Human Health Effects Assays,"Human health effects assays are reviewed. Current approaches to evaluating potential human health hazards of environmental chemical exposure as obtained from literature surveys are summarized. Test systems for determining genotoxic effects are noted. Several authors have pointed out that because of the hundred to thousand fold differences in interspecies responses often observed under uniform test conditions, extrapolation of xenobiotic effects from one test system to another is risky at best. The literature dealing with analysis of environmental samples is reviewed. Literature concerned with the effects of specific chemical agents is summarized. Studies of arsenic (7440382), hexavalent chromium (18540299), trivalent chromium (16065831), mercury (7439976) compounds, and polycyclic aromatic compounds are cited. The National Cancer Institute has sponsored studies of classes of compounds in order to identify specific compounds for carcinogenicity studies. Reports on studies of ethers, aryl sulfonamides, and metals have been prepared. Studies of bacterial assays obtained from the literature are summarized.","Human Health Effects Assays Abs: Human health effects assays are reviewed. Current approaches to evaluating potential human health hazards of environmental chemical exposure as obtained from literature surveys are summarized. Test systems for determining genotoxic effects are noted. Several authors have pointed out that because of the hundred to thousand fold differences in interspecies responses often observed under uniform test conditions, extrapolation of xenobiotic effects from one test system to another is risky at best. The literature dealing with analysis of environmental samples is reviewed. Literature concerned with the effects of specific chemical agents is summarized. Studies of arsenic (7440382), hexavalent chromium (18540299), trivalent chromium (16065831), mercury (7439976) compounds, and polycyclic aromatic compounds are cited. The National Cancer Institute has sponsored studies of classes of compounds in order to identify specific compounds for carcinogenicity studies. Reports on studies of ethers, aryl sulfonamides, and metals have been prepared. Studies of bacterial assays obtained from the literature are summarized."
1516444,Simonsson 1997,Electrochemistry for a cleaner environment,Biosis copyright: biol abs. rrm literature review waste treatment methods toxic species anodic oxidation contaminated groundwater contaminated soil electrochemical sensing pollution methodology electrochemistry waste treatment method detoxification method analytical method,Electrochemistry for a cleaner environment Abs: Biosis copyright: biol abs. rrm literature review waste treatment methods toxic species anodic oxidation contaminated groundwater contaminated soil electrochemical sensing pollution methodology electrochemistry waste treatment method detoxification method analytical method
1516442,Simon et al. 1987,Modifications of physical and chemical soil properties by application of treated petrochemical effluent,Biosis copyright: biol abs. rrm tree grass shrub metals cadmium root phytotoxicity soil pollution environmental surveillance waste management waste disposal industrial waste petrochemicals industry,Modifications of physical and chemical soil properties by application of treated petrochemical effluent Abs: Biosis copyright: biol abs. rrm tree grass shrub metals cadmium root phytotoxicity soil pollution environmental surveillance waste management waste disposal industrial waste petrochemicals industry
1516440,Signorile and  D'Angelo 1980,Toxic effect in vitro of hexavalent chromium on freshwater rotifera and planktonic crustacea,"HEEP COPYRIGHT: BIOL ABS. Toxic effect of hexavalent Cr on Philodina sp. (Rotifera), Cyclops sp. (Copepoda) and Cypria ophthalmica (Ostracoda) was studied. Toxic effects of hexavalent Cr were assessed on the basis of mortality rate and time of exposure of test animals to different concentrations of metal ion at 20ê C. These toxic effects were different on each species. Hexavalent Cr was least toxic to C. ophthalmica.","Toxic effect in vitro of hexavalent chromium on freshwater rotifera and planktonic crustacea Abs: HEEP COPYRIGHT: BIOL ABS. Toxic effect of hexavalent Cr on Philodina sp. (Rotifera), Cyclops sp. (Copepoda) and Cypria ophthalmica (Ostracoda) was studied. Toxic effects of hexavalent Cr were assessed on the basis of mortality rate and time of exposure of test animals to different concentrations of metal ion at 20ê C. These toxic effects were different on each species. Hexavalent Cr was least toxic to C. ophthalmica."
1516438,Shumilla and  Barchowsky 1998,Metabolism of crvi inhibits nf-kappab activity and cytokine-induced upa expression,Biosis copyright: biol abs. rrm meeting abstract a549 cell line carcinogen treatment human lung cancer cell line tumor biology chromium-vi pulmonary carcinogen metabolism nuclear factor-kappa-b chromium metabolism inhibition tumor cell expression urokinase type plasminogen activator cytokine-induced tumor cell expression,Metabolism of crvi inhibits nf-kappab activity and cytokine-induced upa expression Abs: Biosis copyright: biol abs. rrm meeting abstract a549 cell line carcinogen treatment human lung cancer cell line tumor biology chromium-vi pulmonary carcinogen metabolism nuclear factor-kappa-b chromium metabolism inhibition tumor cell expression urokinase type plasminogen activator cytokine-induced tumor cell expression
1516436,Shofstahl et al. 1989,Method for the determination of chromium(VI) as chromium(VI)-dibenzyldithiocarbamate,"BIOSIS COPYRIGHT: BIOL ABS. Dibenzyldithiocarbamic acid (DBDC) exhibits the ability to speciate between chromium (VI) and chromium (III), since only the chromium (VI) will form complexes with DBDC. The complex is then extracted into an organic solvent and assayed using an ultraviolet-visible (UV-VIS) spectrophotometer at 498.8 nm. Using 250 ml of aqueous sample detection limits less than 1 ng/ml are possible, while the linear range extends to 500 mug/ml when working at 498.8 nm. Oxidation of the chromium (III) to chromium (VI) using cerium (IV) enables the determination of total chromium and subsequently the chromium (III) in solution. Evaluation of the method with a standard reference material produced only 4.81 part per thousand error in the determination of chromium (VI).","Method for the determination of chromium(VI) as chromium(VI)-dibenzyldithiocarbamate Abs: BIOSIS COPYRIGHT: BIOL ABS. Dibenzyldithiocarbamic acid (DBDC) exhibits the ability to speciate between chromium (VI) and chromium (III), since only the chromium (VI) will form complexes with DBDC. The complex is then extracted into an organic solvent and assayed using an ultraviolet-visible (UV-VIS) spectrophotometer at 498.8 nm. Using 250 ml of aqueous sample detection limits less than 1 ng/ml are possible, while the linear range extends to 500 mug/ml when working at 498.8 nm. Oxidation of the chromium (III) to chromium (VI) using cerium (IV) enables the determination of total chromium and subsequently the chromium (III) in solution. Evaluation of the method with a standard reference material produced only 4.81 part per thousand error in the determination of chromium (VI)."
1516435,Shin et al. 1988,Design optimization for solidification of hazardous wastes,Biosis copyright: biol abs. rrm electroplating industry sand cement water leaching zinc chromium compressive strength,Design optimization for solidification of hazardous wastes Abs: Biosis copyright: biol abs. rrm electroplating industry sand cement water leaching zinc chromium compressive strength
1516434,Shimada 1979,Effects of chromium vi on growth and enzyme production of chromium resistant bacteria,Heep copyright: biol abs. abstract pseudomonas-sp toxicity secretion glucose,Effects of chromium vi on growth and enzyme production of chromium resistant bacteria Abs: Heep copyright: biol abs. abstract pseudomonas-sp toxicity secretion glucose
1516433,Sheehan et al. 1990,Development and field validation of a sampling and analytical method for airborne hexavalent chromium,Biosis copyright: biol abs. rrm human pollution workplace contaminated soil,Development and field validation of a sampling and analytical method for airborne hexavalent chromium Abs: Biosis copyright: biol abs. rrm human pollution workplace contaminated soil
1516431,Shi et al. 1990,One electron reduction of chromium-vi by microsomes and generation of hydroxyl radical,Biosis copyright: biol abs. rrm abstract free radicals nadph complex dna adduct genotoxicity esr,One electron reduction of chromium-vi by microsomes and generation of hydroxyl radical Abs: Biosis copyright: biol abs. rrm abstract free radicals nadph complex dna adduct genotoxicity esr
1516429,Shi and  Dalal 1990,Evidence for a Fenton-type mechanism for the generation of hydroxyl radicals in the reduction of chromium(VI) in cellular media,"BIOSIS COPYRIGHT: BIOL ABS. Electron spin resonance (ESR) spectroscopy has been employed to examine the role of tetraperoxochromate(V) ions (CrO83-) and other Cr(V) species in the generation of hydroxyl (.OH) radicals in the reaction of Cr(VI) with H2O2 in biological media. In contrast to earlier suggestions, the present ESR studies using crystalline K3CrO8 as a source of CrO83- show that decomposition of CrO83- in water or in H2O2 does not generate significant amounts of .OH radicals. Addition of NADH to a solution containing CrO83- yields a Cr(V)-NADH complex, which readily reacts with H2O2 to generate .OH radicals. Similar results obtained from several other biological reductants, including vitamin B2, indicate that a vacant coordination site on a Cr(V) complex facilitates its reaction with H2O2 to generate .OH radicals.","Evidence for a Fenton-type mechanism for the generation of hydroxyl radicals in the reduction of chromium(VI) in cellular media Abs: BIOSIS COPYRIGHT: BIOL ABS. Electron spin resonance (ESR) spectroscopy has been employed to examine the role of tetraperoxochromate(V) ions (CrO83-) and other Cr(V) species in the generation of hydroxyl (.OH) radicals in the reaction of Cr(VI) with H2O2 in biological media. In contrast to earlier suggestions, the present ESR studies using crystalline K3CrO8 as a source of CrO83- show that decomposition of CrO83- in water or in H2O2 does not generate significant amounts of .OH radicals. Addition of NADH to a solution containing CrO83- yields a Cr(V)-NADH complex, which readily reacts with H2O2 to generate .OH radicals. Similar results obtained from several other biological reductants, including vitamin B2, indicate that a vacant coordination site on a Cr(V) complex facilitates its reaction with H2O2 to generate .OH radicals."
1516426,Shen and  Wang 1995,Simultaneous chromium reduction and phenol degradation in a coculture of Escherichia coli ATCC 33456 and Pseudomonas putida DMP-1,"BIOSIS COPYRIGHT: BIOL ABS. In a defined coculture of a Cr(VI) reducer, Escherichia coli ATCC 33456, and a phenol degrader, Pseudomonas putida DMP-1, simultaneous reduction of Cr(VI) and degradation of phenol was observed. When Cr(VI) was present in the coculture, quantitative transformation of Cr(VI) into Cr(III) proceeded with simultaneous degradation of phenol. Cr(VI) reduction was correlated to phenol degradation in the coculture as demonstrated by a regression analysis of the cumulative Cr(VI) reduction and the cumulative phenol degradation. Both the rate and extent of Cr(VI) reduction and phenol degradation were significantly influenced by the population composition of the coculture. Although Cr(VI) reduction occurred as a result of E. coli metabolism, the rate of phenol degradation by P. putida may become a rate-limiting factor for Cr(VI) reduction at a low population ratio of P. putida to E. coli. Phenol degradation by P. putida was very susceptible to the presence of Cr(VI), whereas Cr(V","Simultaneous chromium reduction and phenol degradation in a coculture of Escherichia coli ATCC 33456 and Pseudomonas putida DMP-1 Abs: BIOSIS COPYRIGHT: BIOL ABS. In a defined coculture of a Cr(VI) reducer, Escherichia coli ATCC 33456, and a phenol degrader, Pseudomonas putida DMP-1, simultaneous reduction of Cr(VI) and degradation of phenol was observed. When Cr(VI) was present in the coculture, quantitative transformation of Cr(VI) into Cr(III) proceeded with simultaneous degradation of phenol. Cr(VI) reduction was correlated to phenol degradation in the coculture as demonstrated by a regression analysis of the cumulative Cr(VI) reduction and the cumulative phenol degradation. Both the rate and extent of Cr(VI) reduction and phenol degradation were significantly influenced by the population composition of the coculture. Although Cr(VI) reduction occurred as a result of E. coli metabolism, the rate of phenol degradation by P. putida may become a rate-limiting factor for Cr(VI) reduction at a low population ratio of P. putida to E. coli. Phenol degradation by P. putida was very susceptible to the presence of Cr(VI), whereas Cr(V"
1516425,Shen et al. 1996,Microbial reduction of Cr(VI) during anaerobic degradation of benzoate,"BIOSIS COPYRIGHT: BIOL ABS. A series of microcosms and enrichments were conducted to evaluate the potential for microbially mediated Cr(VI) reduction linked to benzoate catabolism. Bacterial degradation of benzoate with the transport of electrons to Cr(VI) was achieved using nitrate or molecular oxygen as an initial stimulator. After depletion of nitrate or oxygen, microcosms and enrichments still retained the capacity for benzoate degradation linked to Cr(VI) reduction. Experiments demonstrated that benzoate degradation occurred concurrently with the reduction of Cr(VI) and was strongly dependent on the presence of Cr(VI). Benzoate degradation proceeded as long as Cr(VI) was present, ceased when Cr(VI) was completely removed, and continued once Cr(VI) was added. Furthermore, the observed benzoate removal, linearly correlated with Cr(VI) consumed, and the stoichiometric ratio were in good agreement to the theoretical ratio for the complete oxidation of benzoate to carbon dioxide coupled to the red","Microbial reduction of Cr(VI) during anaerobic degradation of benzoate Abs: BIOSIS COPYRIGHT: BIOL ABS. A series of microcosms and enrichments were conducted to evaluate the potential for microbially mediated Cr(VI) reduction linked to benzoate catabolism. Bacterial degradation of benzoate with the transport of electrons to Cr(VI) was achieved using nitrate or molecular oxygen as an initial stimulator. After depletion of nitrate or oxygen, microcosms and enrichments still retained the capacity for benzoate degradation linked to Cr(VI) reduction. Experiments demonstrated that benzoate degradation occurred concurrently with the reduction of Cr(VI) and was strongly dependent on the presence of Cr(VI). Benzoate degradation proceeded as long as Cr(VI) was present, ceased when Cr(VI) was completely removed, and continued once Cr(VI) was added. Furthermore, the observed benzoate removal, linearly correlated with Cr(VI) consumed, and the stoichiometric ratio were in good agreement to the theoretical ratio for the complete oxidation of benzoate to carbon dioxide coupled to the red"
1516424,Sheehy 1982,"In-Depth Survey Report of U.S. Chrome, Fond du Lac, Wisconsin","An indepth survey of control technology was conducted at US Chrome (SIC-3471), Fond du Lac, Wisconsin, in September 1981. The survey was conducted to evaluate engineering control technology used in a production plating and cleaning operation. Personal air samples were collected for hexavalent-chromium (18540299) (CrVI), sulfuric-acid (7664939), and nitric-acid (7697372). Area samples were also collected for these and for chromium (7440473) (Cr) and hydrofluoric-acid (7664393). OSHA permissible exposure limits for CrVI, sulfuric-acid, and nitric-acid were 0.100, 1.0, and 5.0 milligrams per cubic meter, respectively, for an 8 hour time weighted average. Personal samples showed good control of CrVI, Cr, sulfuric-acid, and nitric-acid for most tanks. A mixed acid tank showed escape of some sulfuric-acid not captured by the one sided local exhaust ventilation. Low exposures to Cr compounds and acids were due to good local exhaust ventilation, low density of plating and cleaning tanks, high ceilings, and general exhaust ventilation. A 300 percent increase in plating production did not affect Cr concentrations in the room air or around the tanks. The author recommends the facility for a followup study to test the hypothesis that higher plating production increases emissions and worker exposure.","In-Depth Survey Report of U.S. Chrome, Fond du Lac, Wisconsin Abs: An indepth survey of control technology was conducted at US Chrome (SIC-3471), Fond du Lac, Wisconsin, in September 1981. The survey was conducted to evaluate engineering control technology used in a production plating and cleaning operation. Personal air samples were collected for hexavalent-chromium (18540299) (CrVI), sulfuric-acid (7664939), and nitric-acid (7697372). Area samples were also collected for these and for chromium (7440473) (Cr) and hydrofluoric-acid (7664393). OSHA permissible exposure limits for CrVI, sulfuric-acid, and nitric-acid were 0.100, 1.0, and 5.0 milligrams per cubic meter, respectively, for an 8 hour time weighted average. Personal samples showed good control of CrVI, Cr, sulfuric-acid, and nitric-acid for most tanks. A mixed acid tank showed escape of some sulfuric-acid not captured by the one sided local exhaust ventilation. Low exposures to Cr compounds and acids were due to good local exhaust ventilation, low density of plating and cleaning tanks, high ceilings, and general exhaust ventilation. A 300 percent increase in plating production did not affect Cr concentrations in the room air or around the tanks. The author recommends the facility for a followup study to test the hypothesis that higher plating production increases emissions and worker exposure."
1516422,Shea et al. 1947,Respiratory Excretion of Methyl Alcohol by White Rats,"The respiratory excretion of methyl-alcohol (67561) was investigated in rats. Rats were fed 1983 milligrams of methyl-alcohol. Respiratory samples were analyzed for oxidizable material. The total amount was extrapolated for a 24 hour period after determination of methyl-alcohol by reduction of potassium-dichromate. During the 24 hours following administration of methyl-alcohol, the rats lost an average of 11.7 percent by way of the respiratory tract. During the second 24 hour period, the average loss was 9.5 percent; with 5.5 and 2.1 percent lost during the next two 24 hour periods, respectively. An average of 31 percent of the total methyl-alcohol dose was excreted by the respiratory system. In rats exposed to an 8 percent carbon-dioxide (124389) (CO2) atmosphere for 90 minutes, excretion of methyl-alcohol was not different from rats given the alcohol alone, although there was a marked increase in respiratory rate and amplitude. The authors conclude that the difficulties reported by other investigators are overcome by the use of a face mask for collecting respired air, and by the use of a colorimetric method to determine methyl-alcohol in the respiratory products.","Respiratory Excretion of Methyl Alcohol by White Rats Abs: The respiratory excretion of methyl-alcohol (67561) was investigated in rats. Rats were fed 1983 milligrams of methyl-alcohol. Respiratory samples were analyzed for oxidizable material. The total amount was extrapolated for a 24 hour period after determination of methyl-alcohol by reduction of potassium-dichromate. During the 24 hours following administration of methyl-alcohol, the rats lost an average of 11.7 percent by way of the respiratory tract. During the second 24 hour period, the average loss was 9.5 percent; with 5.5 and 2.1 percent lost during the next two 24 hour periods, respectively. An average of 31 percent of the total methyl-alcohol dose was excreted by the respiratory system. In rats exposed to an 8 percent carbon-dioxide (124389) (CO2) atmosphere for 90 minutes, excretion of methyl-alcohol was not different from rats given the alcohol alone, although there was a marked increase in respiratory rate and amplitude. The authors conclude that the difficulties reported by other investigators are overcome by the use of a face mask for collecting respired air, and by the use of a colorimetric method to determine methyl-alcohol in the respiratory products."
1516421,Shashikanth and  Shantha 1993,Adsorption studies of chromium (VI) from synthetic aqueous solution by activated carbon derived from bagasse,"BIOSIS COPYRIGHT: BIOL ABS. The removal of chromium (VI) from synthetic waste water by adsorption on activated carbon prepared from Bagasse (solid waste produced by sugar industries) was tried to determine the effects of different dosages and different pH. The removal of chromium (VI) from synthetic waste water by adsorption on two types of activated carbon, physical activation and chemical activation (CaCl2 & MgCl2), IRs 0.25, 0.5, 0.75, different pH and different dosages was studied. It was observed that as dosage increases the adsorption increased along with the increase in IR. It was also noted as IR increases the surface area of Bagasse carbon increased. These dosage data were considered in the construction of isotherms. And it was found adsorption follows Freundlich, Langmuir and BET isotherms. The maximum removal of chromium (VI) is obtained at pH 2.0. MH - MINERALS","Adsorption studies of chromium (VI) from synthetic aqueous solution by activated carbon derived from bagasse Abs: BIOSIS COPYRIGHT: BIOL ABS. The removal of chromium (VI) from synthetic waste water by adsorption on activated carbon prepared from Bagasse (solid waste produced by sugar industries) was tried to determine the effects of different dosages and different pH. The removal of chromium (VI) from synthetic waste water by adsorption on two types of activated carbon, physical activation and chemical activation (CaCl2 & MgCl2), IRs 0.25, 0.5, 0.75, different pH and different dosages was studied. It was observed that as dosage increases the adsorption increased along with the increase in IR. It was also noted as IR increases the surface area of Bagasse carbon increased. These dosage data were considered in the construction of isotherms. And it was found adsorption follows Freundlich, Langmuir and BET isotherms. The maximum removal of chromium (VI) is obtained at pH 2.0. MH - MINERALS"
1516419,Sharma and  Forster 1996,Removal of hexavalent chromium from aqueous solutions by granular activated carbon,"BIOSIS COPYRIGHT: BIOL ABS. Batch absorption trials were used to assess the effectiveness of using activated carbon as a sorbent for the removal of hexavalent chromium from solution. The results show that, although the pH for maximum efficiency varied slightly with the concentration of Cr(VI) being applied, the most effective pH was in the range 2.5 to 3.0. Based on linear regression analysis, the data obtained from the batch studies showed a good compliance with both the Langmuir and the Freundlich equations. The values obtained for the isotherm constants showed that the maximum adsorption capacity, Xm, was 145 mg/g. An examination of the adsorption kinetics was also made and an analysis of the data shows that pore diffusion is not the only factor governing the sorption rate.","Removal of hexavalent chromium from aqueous solutions by granular activated carbon Abs: BIOSIS COPYRIGHT: BIOL ABS. Batch absorption trials were used to assess the effectiveness of using activated carbon as a sorbent for the removal of hexavalent chromium from solution. The results show that, although the pH for maximum efficiency varied slightly with the concentration of Cr(VI) being applied, the most effective pH was in the range 2.5 to 3.0. Based on linear regression analysis, the data obtained from the batch studies showed a good compliance with both the Langmuir and the Freundlich equations. The values obtained for the isotherm constants showed that the maximum adsorption capacity, Xm, was 145 mg/g. An examination of the adsorption kinetics was also made and an analysis of the data shows that pore diffusion is not the only factor governing the sorption rate."
1516417,Sharma and  Forster 1994,A preliminary examination into the adsorption of hexavalent chromium using low-cost adsorbents,BIOSIS COPYRIGHT: BIOL ABS. Four organic wastes were tested as potential adsorbents for hexavalent chromium. The results showed that this type of material could certainly be considered for this purpose with the best results being achieved at pH vales of 1.5-3.0. The results also showed that cellulosic materials which had been subjected to some degree of anaerobic biodegradation were better adsorbents than fresh cellulosic material.,A preliminary examination into the adsorption of hexavalent chromium using low-cost adsorbents Abs: BIOSIS COPYRIGHT: BIOL ABS. Four organic wastes were tested as potential adsorbents for hexavalent chromium. The results showed that this type of material could certainly be considered for this purpose with the best results being achieved at pH vales of 1.5-3.0. The results also showed that cellulosic materials which had been subjected to some degree of anaerobic biodegradation were better adsorbents than fresh cellulosic material.
1516416,Sharma and  Forster 1993,Removal of hexavalent chromium using sphagnum moss peat,"BIOSIS COPYRIGHT: BIOL ABS. Batch adsorption studies have shown that sphagnum moss peat, which is essentially oligotrophic, in concentrations ranging from 4 to 40 g/l can be used effectively to remove hexavalent chromium from aqueous solutions. The process is pH dependent, the optimum range being 1.5-3. Treatment of the exhausted peat with 1 M NaOH removed only 50% of the sorbed metal, suggesting that the binding to the peat involved strong chemisorption forces.","Removal of hexavalent chromium using sphagnum moss peat Abs: BIOSIS COPYRIGHT: BIOL ABS. Batch adsorption studies have shown that sphagnum moss peat, which is essentially oligotrophic, in concentrations ranging from 4 to 40 g/l can be used effectively to remove hexavalent chromium from aqueous solutions. The process is pH dependent, the optimum range being 1.5-3. Treatment of the exhausted peat with 1 M NaOH removed only 50% of the sorbed metal, suggesting that the binding to the peat involved strong chemisorption forces."
1516415,Shanker et al. 1995,Studies on se-cr interactions in mungbean using radiotracers,Biosis copyright: biol abs. rrm research article phaseolus-mungo selenium-chromium contaminant metals uptake hydroponic studies,Studies on se-cr interactions in mungbean using radiotracers Abs: Biosis copyright: biol abs. rrm research article phaseolus-mungo selenium-chromium contaminant metals uptake hydroponic studies
1516411,Sewell and  Gibson 1993,Reduction of chromium-vi to chromium-iii in anaerobic aquifer microcosms,Biosis copyright: biol abs. rrm abstract chromium pollution bioremediation ethanol benzoate sulfide ferric iron,Reduction of chromium-vi to chromium-iii in anaerobic aquifer microcosms Abs: Biosis copyright: biol abs. rrm abstract chromium pollution bioremediation ethanol benzoate sulfide ferric iron
1516410,Seshaiah et al. 1987,Potentiometric determination of chromium(VI) in water,"BIOSIS COPYRIGHT: BIOL ABS. Potentiometric method for the determination of chromium(VI) in water is described. Chromium(VI) in water is preconcentrated by co-preciptation with BaSO4, the precipitate is fused with alkali carbonate and Cr(VI) in the melt is dissolved with hot water and determined potentiometrically by titrating with a standard ascorbic acid solution in sulphuric acid medium.","Potentiometric determination of chromium(VI) in water Abs: BIOSIS COPYRIGHT: BIOL ABS. Potentiometric method for the determination of chromium(VI) in water is described. Chromium(VI) in water is preconcentrated by co-preciptation with BaSO4, the precipitate is fused with alkali carbonate and Cr(VI) in the melt is dissolved with hot water and determined potentiometrically by titrating with a standard ascorbic acid solution in sulphuric acid medium."
1516407,Sen and  Costa 1986,Incidence and localization of sister chromatid exchanges induced by nickel and chromium compounds,"Carcinogenic nickel compounds enhanced the incidence of sister chromatid exchanges (SCEs) in a concentration-dependent fashion in intact Chinese hamster ovary cells. There was a preferential induction of these exchanges in the heterochromatic regions of the chromosomes. CaCrO4 also caused a dose-dependent induction of SCEs. However, in contrast to NiCl2, the exchanges induced by CaCrO4 were not localized in any particular chromosomal region. The total incidence of exchanges was higher with CaCrO4 than with NiCl2. CaCrO4, crystalline NiS and NiCl2 enhanced the incidence of SCEs at concentrations below the threshold of DNA damage as detected by the technique of alkaline elution. Additionally, following treatment time intervals of 24-48 h, there was an increase in SCEs at concentrations of NiCl2 or CaCrO4 that produced little disruption of cell cycle progression. These results are consistent with the hypothesis that potently carcinogenic nickel compounds which are not very mutagenic exert selective effects on genetically inactive heterochromatin, while potently mutagenic and carcinogenic chromate do not appear to produce a similar predominance of SCEs in heterochromatic regions.","Incidence and localization of sister chromatid exchanges induced by nickel and chromium compounds Abs: Carcinogenic nickel compounds enhanced the incidence of sister chromatid exchanges (SCEs) in a concentration-dependent fashion in intact Chinese hamster ovary cells. There was a preferential induction of these exchanges in the heterochromatic regions of the chromosomes. CaCrO4 also caused a dose-dependent induction of SCEs. However, in contrast to NiCl2, the exchanges induced by CaCrO4 were not localized in any particular chromosomal region. The total incidence of exchanges was higher with CaCrO4 than with NiCl2. CaCrO4, crystalline NiS and NiCl2 enhanced the incidence of SCEs at concentrations below the threshold of DNA damage as detected by the technique of alkaline elution. Additionally, following treatment time intervals of 24-48 h, there was an increase in SCEs at concentrations of NiCl2 or CaCrO4 that produced little disruption of cell cycle progression. These results are consistent with the hypothesis that potently carcinogenic nickel compounds which are not very mutagenic exert selective effects on genetically inactive heterochromatin, while potently mutagenic and carcinogenic chromate do not appear to produce a similar predominance of SCEs in heterochromatic regions."
1516406,Sen et al. 1987,Studies of uptake and toxic effects of chromium vi on pistia-stratiotes,Biosis copyright: biol abs. rrm metals wastewater treatment waste management water pollution enzyme chlorophyll dna rna,Studies of uptake and toxic effects of chromium vi on pistia-stratiotes Abs: Biosis copyright: biol abs. rrm metals wastewater treatment waste management water pollution enzyme chlorophyll dna rna
1516405,Selvarani and  Subbiah 1994,Toxicity study of chromium in the fresh water fish Macrones keletius and the role of Eichhornia crassipes in its control,"BIOSIS COPYRIGHT: BIOL ABS. Experiments were carried out to study the effect of water plant, Eichhornia to control the chromium residues (trivalent + hexavalent) in a fresh water fish, Macrones keletius. Hundred percent mortality was observed at a concentration of 42 ppm chromium. The LC50 value was found to be 26.4 ppm. At a concentration of 6 ppm and below, the fishes survived without any stress. So 6 ppm and below is considered to be the sub-lethal or around sub-lethal concentration. The rate of oxygen consumption decreased by 66.67% in control fishes, raised without aquatic plant, while experimental fishes, raised with aquatic plant, showed a drop of 58.99%. The protein content in the muscle tissue of experimental fishes was minimized by 18.29%. The heavy metal chromium accumulation in the muscle tissue of the control fish was more significant (65.23%) than that of the experimental ones. The loss of energy was also found to be higher (1.35% higher) in the control fishes than that of the experi","Toxicity study of chromium in the fresh water fish Macrones keletius and the role of Eichhornia crassipes in its control Abs: BIOSIS COPYRIGHT: BIOL ABS. Experiments were carried out to study the effect of water plant, Eichhornia to control the chromium residues (trivalent + hexavalent) in a fresh water fish, Macrones keletius. Hundred percent mortality was observed at a concentration of 42 ppm chromium. The LC50 value was found to be 26.4 ppm. At a concentration of 6 ppm and below, the fishes survived without any stress. So 6 ppm and below is considered to be the sub-lethal or around sub-lethal concentration. The rate of oxygen consumption decreased by 66.67% in control fishes, raised without aquatic plant, while experimental fishes, raised with aquatic plant, showed a drop of 58.99%. The protein content in the muscle tissue of experimental fishes was minimized by 18.29%. The heavy metal chromium accumulation in the muscle tissue of the control fish was more significant (65.23%) than that of the experimental ones. The loss of energy was also found to be higher (1.35% higher) in the control fishes than that of the experi"
1516404,Selomulya et al. 1999,Mechanisms of Cr(VI) removal from water by various types of activated carbons,"BIOSIS COPYRIGHT: BIOL ABS. The removal mechanisms of Cr(VI) from water using different types of activated carbons, produced from coconut shell, wood and dust coal, were investigated in this project. Different types of activated carbons have different surface characteristics. The coconut shell and dust coal activated carbons have protonated hydroxyl groups on the surface (H-type carbons), while the surface of the wood-based activated carbon has ionised hydroxyl groups (L-type carbons). The adsorption kinetics of chromium o aracteristics and capacity of the activated carbons to reduce Cr(VI) to Cr(III).","Mechanisms of Cr(VI) removal from water by various types of activated carbons Abs: BIOSIS COPYRIGHT: BIOL ABS. The removal mechanisms of Cr(VI) from water using different types of activated carbons, produced from coconut shell, wood and dust coal, were investigated in this project. Different types of activated carbons have different surface characteristics. The coconut shell and dust coal activated carbons have protonated hydroxyl groups on the surface (H-type carbons), while the surface of the wood-based activated carbon has ionised hydroxyl groups (L-type carbons). The adsorption kinetics of chromium o aracteristics and capacity of the activated carbons to reduce Cr(VI) to Cr(III)."
1516395,Seaman et al. 1999,"In situ Cr(VI) reduction within coarse-textured, oxide-coated soil and aquifer systems using Fe(II) solutions","BIOSIS COPYRIGHT: BIOL ABS. Batch and column techniques were used to evaluate the in situ Cr(VI) reduction and immobilization using Fe(II) solutions within the sediments of the Atlantic Coastal Plain. Remediation treatments included Cr-free groundwater and buffered and unbuffered Fe(II) solutions as either FeCl2 and FeSO4. The slow release of Cr(VI) from the Fe-oxide rich subsurface sediment following exposure to Cr-free solutions indicated that simple pump-and-treat procedures would require extended operation time to meet .0) induced by oxidation and hydrolysis of Fe(II). Acetate-buffered Fe(II) solutions maintained an elevated pH in the presence of Cr-(VI) reduction, making the treatment effective at lowering CrDissolved in batch evaluations. Acetate increased Cr(VI) mobility in columns ahead of the reactive Fe(II) front, suggesting that in situ reduction using soluble chemical additives may be somewhat ineffective due to the enhanced migration of Cr, either Cr(III) or Cr(VI), induced by the trea","In situ Cr(VI) reduction within coarse-textured, oxide-coated soil and aquifer systems using Fe(II) solutions Abs: BIOSIS COPYRIGHT: BIOL ABS. Batch and column techniques were used to evaluate the in situ Cr(VI) reduction and immobilization using Fe(II) solutions within the sediments of the Atlantic Coastal Plain. Remediation treatments included Cr-free groundwater and buffered and unbuffered Fe(II) solutions as either FeCl2 and FeSO4. The slow release of Cr(VI) from the Fe-oxide rich subsurface sediment following exposure to Cr-free solutions indicated that simple pump-and-treat procedures would require extended operation time to meet .0) induced by oxidation and hydrolysis of Fe(II). Acetate-buffered Fe(II) solutions maintained an elevated pH in the presence of Cr-(VI) reduction, making the treatment effective at lowering CrDissolved in batch evaluations. Acetate increased Cr(VI) mobility in columns ahead of the reactive Fe(II) front, suggesting that in situ reduction using soluble chemical additives may be somewhat ineffective due to the enhanced migration of Cr, either Cr(III) or Cr(VI), induced by the trea"
1516394,Scott and  Proctor 1997,Evaluation of 10 percent minimum elicitation threshold for Cr(VI)-induced allergic contact dermatitis using benchmark dose methods,"BIOSIS COPYRIGHT: BIOL ABS. Historical patch test data have been used to propose health-based soil cleanup levels for Cr(VI) that are protective of eliciting allergic contact dermatitis (ACD) among previously sensitized individuals. Shortcomings regarding the use of these historical studies in the risk assessment of Cr(VI) have been identified and include the use of concentration as the dosimetric for ACD elicitation rather than the mass per surface area. Information on the surface areas of the patches used by the authors of three of the historical studies have been made available recently, and their dose levels have been converted from units of concentration to mass per surface area. For this study, benchmark dose methods were used to estimate the 10% minimum elicitation threshold (MET) based on the converted patch test data from these historical studies and from the data presented in a more recent patch test study by Nethercott et al. (1994). A truncated lognormal model was fitted to the histori","Evaluation of 10 percent minimum elicitation threshold for Cr(VI)-induced allergic contact dermatitis using benchmark dose methods Abs: BIOSIS COPYRIGHT: BIOL ABS. Historical patch test data have been used to propose health-based soil cleanup levels for Cr(VI) that are protective of eliciting allergic contact dermatitis (ACD) among previously sensitized individuals. Shortcomings regarding the use of these historical studies in the risk assessment of Cr(VI) have been identified and include the use of concentration as the dosimetric for ACD elicitation rather than the mass per surface area. Information on the surface areas of the patches used by the authors of three of the historical studies have been made available recently, and their dose levels have been converted from units of concentration to mass per surface area. For this study, benchmark dose methods were used to estimate the 10% minimum elicitation threshold (MET) based on the converted patch test data from these historical studies and from the data presented in a more recent patch test study by Nethercott et al. (1994). A truncated lognormal model was fitted to the histori"
1516392,Schroll 1978,Determination of the absorption of chromium vi and chromium iii in an algal culture of chlorella-pyrenoidosa using chromium-51,Heep copyright: biol abs. pollution,Determination of the absorption of chromium vi and chromium iii in an algal culture of chlorella-pyrenoidosa using chromium-51 Abs: Heep copyright: biol abs. pollution
1516391,Schroeder 1970,Chromium,"Though trivalent chromium is an essential trace element for glucose, lipid and amino acid metabolism, hexavalent chromium is a strong oxidizing agent irritating to living cells. After low exposures to high concentrations, it is found to cause bronchogenic carcinoma. A maximum level of 0.5 microgram per cubic meter is considered reasonable for the population at large, and 50 micrograms per cubic meter for industrial workers. Airborne chromium (7440473) in the United States cities is deemed to have declined considerably since 1954.","Chromium Abs: Though trivalent chromium is an essential trace element for glucose, lipid and amino acid metabolism, hexavalent chromium is a strong oxidizing agent irritating to living cells. After low exposures to high concentrations, it is found to cause bronchogenic carcinoma. A maximum level of 0.5 microgram per cubic meter is considered reasonable for the population at large, and 50 micrograms per cubic meter for industrial workers. Airborne chromium (7440473) in the United States cities is deemed to have declined considerably since 1954."
1516390,Schneeberger and  Forck 1974,Experimental chromium allergy of animals: The influence of valences and chemical properties of chromium ions,"HEEP COPYRIGHT: BIOL ABS. Contact sensitization and allergic reactions by haxavalent and trivalent Cr salts in aqueous solutions using the detergent Triton-X-100 (2%) were successfully achieved in guinea pigs. Chromate and dichromate ions demonstrate an excellent potency of sensitization. In trivalent Cr compounds the complexity strength of the chromic complex must be considered. The sensitization capability of these complexes is inversely proportional to the complex strength. This indicates a kinetically or thermodynamically hindered chemical reaction in which a complete antigen is developed by binding of Cr-III-ion at a functional point of human protein. The trivalency level has also a decisive function in the sensitization by the chromate (dichromate ion), the reduction of which, when penetrating the skin, seems probable. Studies on sensitization with water insoluble Cr-III-compounds show only a few seakly positive eczematous reactions.","Experimental chromium allergy of animals: The influence of valences and chemical properties of chromium ions Abs: HEEP COPYRIGHT: BIOL ABS. Contact sensitization and allergic reactions by haxavalent and trivalent Cr salts in aqueous solutions using the detergent Triton-X-100 (2%) were successfully achieved in guinea pigs. Chromate and dichromate ions demonstrate an excellent potency of sensitization. In trivalent Cr compounds the complexity strength of the chromic complex must be considered. The sensitization capability of these complexes is inversely proportional to the complex strength. This indicates a kinetically or thermodynamically hindered chemical reaction in which a complete antigen is developed by binding of Cr-III-ion at a functional point of human protein. The trivalency level has also a decisive function in the sensitization by the chromate (dichromate ion), the reduction of which, when penetrating the skin, seems probable. Studies on sensitization with water insoluble Cr-III-compounds show only a few seakly positive eczematous reactions."
1516388,Schmitz et al. 1998,"Miniaturized kinetic growth inhibition assays with Vibrio fischeri and Pseudomonas putida (application, validation and comparison)","BIOSIS COPYRIGHT: BIOL ABS. Two miniaturized growth inhibition assays with Vibrio fischeri and Pseudomonas putida, based on the German DIN Standards 38 412-37 and 38 412-8 are presented. Different calculation modes are compared on the basis of measuring toxicological effects (EC50 and EC20 values) of several heavy metals and other reference substances. They demonstrate the higher sensitivity of the Pseudomonas putida test. The results point out the insufficiency of the endpoint calculation mode. Therefore, a modified integral data analysis procedure is recommended. Possibilities and limits of the test protocols and kinetic data recordings are discussed.","Miniaturized kinetic growth inhibition assays with Vibrio fischeri and Pseudomonas putida (application, validation and comparison) Abs: BIOSIS COPYRIGHT: BIOL ABS. Two miniaturized growth inhibition assays with Vibrio fischeri and Pseudomonas putida, based on the German DIN Standards 38 412-37 and 38 412-8 are presented. Different calculation modes are compared on the basis of measuring toxicological effects (EC50 and EC20 values) of several heavy metals and other reference substances. They demonstrate the higher sensitivity of the Pseudomonas putida test. The results point out the insufficiency of the endpoint calculation mode. Therefore, a modified integral data analysis procedure is recommended. Possibilities and limits of the test protocols and kinetic data recordings are discussed."
1516384,Sawyer 1988,Chromium and Its Compounds,"The biological effects of exposure to chromium (7440473) and associated compounds were reviewed and discussed. The chemical properties of chromium, along with its production and industrial sources were described. Exposure to chromium or related compounds by skin absorption, ingestion or inhalation, and the resulting biological distribution and elimination were discussed. The need for dietary chromium as an essential trace element was examined. Dietary sources included brewer's yeast, meats, fruits, vegetables, and dark breads. Exposure to hexavalent chromium compounds has been associated with an increased risk of lung cancer. Medical monitoring of workers exposed to chromium compounds was discussed. The current permissible exposure levels determined by OSHA and the American Conference of Governmental Industrial Hygienists were discussed. The author advises workers in contact with hexavalent chromium compounds to refrain from cigarette smoking to avoid possible additive carcinogenic effects.","Chromium and Its Compounds Abs: The biological effects of exposure to chromium (7440473) and associated compounds were reviewed and discussed. The chemical properties of chromium, along with its production and industrial sources were described. Exposure to chromium or related compounds by skin absorption, ingestion or inhalation, and the resulting biological distribution and elimination were discussed. The need for dietary chromium as an essential trace element was examined. Dietary sources included brewer's yeast, meats, fruits, vegetables, and dark breads. Exposure to hexavalent chromium compounds has been associated with an increased risk of lung cancer. Medical monitoring of workers exposed to chromium compounds was discussed. The current permissible exposure levels determined by OSHA and the American Conference of Governmental Industrial Hygienists were discussed. The author advises workers in contact with hexavalent chromium compounds to refrain from cigarette smoking to avoid possible additive carcinogenic effects."
1516383,Sato et al. 1988,Solvent extraction and spectrophotometric determination of chromium vi with crystal violet,Biosis copyright: biol abs. rrm environmental pollution heavy metal degree of absorbance beer's law,Solvent extraction and spectrophotometric determination of chromium vi with crystal violet Abs: Biosis copyright: biol abs. rrm environmental pollution heavy metal degree of absorbance beer's law
1516381,Sarwar et al. 1988,Determination of sexavalent chromium from the effluents of various electroplating industries,Biosis copyright: biol abs. rrm carcinogen wastewater management occupational health and safety,Determination of sexavalent chromium from the effluents of various electroplating industries Abs: Biosis copyright: biol abs. rrm carcinogen wastewater management occupational health and safety
1516380,Sarkunan et al. 1989,Chromium(VI) toxicity in rice grown under flooded condition in an alluvial soil,"BIOSIS COPYRIGHT: BIOL ABS. The phytotoxicity due to Cr(VI) and its likely contamination of food chain resulting from its addition from low to very high levels to an alluvial soil (Haplaquept) under flooded condition in rice was studied in a pot culture experiment. Freshly added Cr (VI) was toxic to rice plants beyond 200 ppm while the residual crop did not exhibit any phytotoxicity even at the highest level of soil application of 1000 ppm. Although Cr could not be detected either in straw or grain, increasing levels of Cr addition significantly increased P, K, Mn and Zn in straw, while a reverse trend was observed for K and Mn contents in grain. It also caused a significant decrease in Ca and Fe content in straw and grain and Mg and Cu in straw. A poor extraction of added Cr by DTPA, 0.5 M and 2.5% acetic acid, 0.01M KH2PO4, 0.1N HCl and 1N NH4OAc as opposed to a high recovery of the residual form extracted by 4M HNO3 in the postharvest soil implied that the added Cr (VI) was transformed into Cr(I","Chromium(VI) toxicity in rice grown under flooded condition in an alluvial soil Abs: BIOSIS COPYRIGHT: BIOL ABS. The phytotoxicity due to Cr(VI) and its likely contamination of food chain resulting from its addition from low to very high levels to an alluvial soil (Haplaquept) under flooded condition in rice was studied in a pot culture experiment. Freshly added Cr (VI) was toxic to rice plants beyond 200 ppm while the residual crop did not exhibit any phytotoxicity even at the highest level of soil application of 1000 ppm. Although Cr could not be detected either in straw or grain, increasing levels of Cr addition significantly increased P, K, Mn and Zn in straw, while a reverse trend was observed for K and Mn contents in grain. It also caused a significant decrease in Ca and Fe content in straw and grain and Mg and Cu in straw. A poor extraction of added Cr by DTPA, 0.5 M and 2.5% acetic acid, 0.01M KH2PO4, 0.1N HCl and 1N NH4OAc as opposed to a high recovery of the residual form extracted by 4M HNO3 in the postharvest soil implied that the added Cr (VI) was transformed into Cr(I"
1516379,Sarkisyan et al. 1971,Certain biochemical and morphological changes in kidneys during chromium poisoning and therapeutic effectiveness of unithiol,"HEEP COPYRIGHT: BIOL ABS. The toxic effect of hexavalent chromium (Cr) on kidney was studied in 270 white rats. Animals of series 1 received 13 mg/kg of Cr as potassium dichromate in drinking water over a period of 90-180 days; series 2 received a single s.c. injection; series 3 received 17 mg/kg; series 4--20; series 5--25 mg/kg in a s.c. injection. 80 mg/kg of unithiol was administered s.c. to some of the rats of the last 3 series: 3 times on the 1st day, twice on the 2nd day and once on the 3rd and 4th days. In order to evaluate the biochemical mechanisms of poisoning, ATPase activity was determined by the Dubois and Potter method with subsequent determination of inorganic P. The number of sulfhydryl groups was determined by amperometric titration, and ascorbic acid dichlorophenolindophenol titration. After 3 mo., experimental animals showed signs of poisoning: lower weight, falling hair, loss of hair luster, skin desquamation, etc. 6 mo., Hb and leukocyte levels were depressed. Unithiol was most effective at Cr doses close to lethal (17 mg/kg) and absolutely lethal (20 mg/kg) in the early period of intoxication (after 0.5 hr). Therapeutic effects were lower at higher doses of Cr. ATPase activity, ascorbic acid, and SH-groups decreased to various degrees, depending on the route of administration and dose of Cr. Unithiol was effective in reducing the mortality from a lethal dose of Cr, in normalizing ATPase activity, number of SH-groups and ascorbic acid in kidney tissue.","Certain biochemical and morphological changes in kidneys during chromium poisoning and therapeutic effectiveness of unithiol Abs: HEEP COPYRIGHT: BIOL ABS. The toxic effect of hexavalent chromium (Cr) on kidney was studied in 270 white rats. Animals of series 1 received 13 mg/kg of Cr as potassium dichromate in drinking water over a period of 90-180 days; series 2 received a single s.c. injection; series 3 received 17 mg/kg; series 4--20; series 5--25 mg/kg in a s.c. injection. 80 mg/kg of unithiol was administered s.c. to some of the rats of the last 3 series: 3 times on the 1st day, twice on the 2nd day and once on the 3rd and 4th days. In order to evaluate the biochemical mechanisms of poisoning, ATPase activity was determined by the Dubois and Potter method with subsequent determination of inorganic P. The number of sulfhydryl groups was determined by amperometric titration, and ascorbic acid dichlorophenolindophenol titration. After 3 mo., experimental animals showed signs of poisoning: lower weight, falling hair, loss of hair luster, skin desquamation, etc. 6 mo., Hb and leukocyte levels were depressed. Unithiol was most effective at Cr doses close to lethal (17 mg/kg) and absolutely lethal (20 mg/kg) in the early period of intoxication (after 0.5 hr). Therapeutic effects were lower at higher doses of Cr. ATPase activity, ascorbic acid, and SH-groups decreased to various degrees, depending on the route of administration and dose of Cr. Unithiol was effective in reducing the mortality from a lethal dose of Cr, in normalizing ATPase activity, number of SH-groups and ascorbic acid in kidney tissue."
1516375,Sanders 1996,Electrochemical reduction of Cr(VI) in the decontamination process ELDECON,"BIOSIS COPYRIGHT: BIOL ABS. One of ABB Atom's methods, ELDECON, is an electrochemical process for decontamination of components used in nuclear power plants. ELDECON removes radioactive species while producing small amounts of waste. However, the waste sludge that is produced in the ELDECON process contains chromate (Cr(VI)). According to the US Cod of Feguration, 40 CFR 261, if a process in any step creates chromate, the final waste has to be tested in a toxicity characteristic leachate procedure. In order to pass the test, the chromate has to be reduced to chromium (Cr(III)). Electrochemistry has proven to be a valuable tool. When incorporating indirect electrolysis into the ELDECON concept, the chromate ions are reduced. This is done by the use of an electrochemical cell (reactor bed). The method involves ferric nitrate as a reagent which, besides converting the chromate completely, also decreases the reaction time. The reaction time and the amount of solution treated in the cell have a close t","Electrochemical reduction of Cr(VI) in the decontamination process ELDECON Abs: BIOSIS COPYRIGHT: BIOL ABS. One of ABB Atom's methods, ELDECON, is an electrochemical process for decontamination of components used in nuclear power plants. ELDECON removes radioactive species while producing small amounts of waste. However, the waste sludge that is produced in the ELDECON process contains chromate (Cr(VI)). According to the US Cod of Feguration, 40 CFR 261, if a process in any step creates chromate, the final waste has to be tested in a toxicity characteristic leachate procedure. In order to pass the test, the chromate has to be reduced to chromium (Cr(III)). Electrochemistry has proven to be a valuable tool. When incorporating indirect electrolysis into the ELDECON concept, the chromate ions are reduced. This is done by the use of an electrochemical cell (reactor bed). The method involves ferric nitrate as a reagent which, besides converting the chromate completely, also decreases the reaction time. The reaction time and the amount of solution treated in the cell have a close t"
1516373,Salunkhe et al. 1998,Bioremediation of hexavalent chromium in soil microcosms,"BIOSIS COPYRIGHT: BIOL ABS. Pseudomonas mendocina when added in soil microcosms could immobilize 100 mug (2 mM) chromate/g soil in 8 h by converting it into trivalent form. The chromate-contaminated soils, after microbiological treatment, supported growth of wheat seedlings without exerting any toxic effects. The method is potentially useful in the bioremediation of chromate-contaminated sites.","Bioremediation of hexavalent chromium in soil microcosms Abs: BIOSIS COPYRIGHT: BIOL ABS. Pseudomonas mendocina when added in soil microcosms could immobilize 100 mug (2 mM) chromate/g soil in 8 h by converting it into trivalent form. The chromate-contaminated soils, after microbiological treatment, supported growth of wheat seedlings without exerting any toxic effects. The method is potentially useful in the bioremediation of chromate-contaminated sites."
1516372,Salnikow et al. 1992,Analysis of the binding sites of chromium to DNA and protein in vitro and in intact cells,"Previous studies have examined Cr(III), or CrO4 reduced to Cr(III), binding in vitro to DNA. However, there have been few studies examining chromate binding to DNA in intact cells. Treatment of intact cells with chromate (Na2(51)CrO4) resulted in chromium (Cr) binding to DNA. The binding of Cr to DNA was much more stable when more residual peptide/amino acids were associated with DNA. A substantial portion of the Cr bound to DNA was released by treatment with EDTA, suggesting that trivalent Cr was the major oxidation state of Cr bound to DNA. Cr(III) stimulated the formation of amino acid-DNA and protein-DNA complexes in vitro. Tyrosine and cysteine exhibited the highest activity in being complexed to DNA by Cr(III) in vitro, while histidine, methionine and threonine also exhibited more activity than any other amino acid. Similar results were found in intact cells. The activity of proteins complexed to DNA by trivalent Cr depended upon the content of these reactive amino acids. Thus, bovine serum albumin was more active than actin, which in turn was more active than histones. These and other studies presented suggested that Cr(III) was involved directly in the formation of DNA-protein complexes in intact cells, unlike other metals such as Ni(II), which are thought to form DNA-protein cross-links catalytically and not participate directly in the complex. The majority of trivalent Cr associated with DNA was bound to the phosphate backbone without exhibiting any base specificity. Collectively, these results indicate that trivalent Cr creates DNA protein crosslinks by binding with reactive amino acids (i.e. cysteine, tyrosine or histidine) and linking these to the phosphate backbone of DNA.","Analysis of the binding sites of chromium to DNA and protein in vitro and in intact cells Abs: Previous studies have examined Cr(III), or CrO4 reduced to Cr(III), binding in vitro to DNA. However, there have been few studies examining chromate binding to DNA in intact cells. Treatment of intact cells with chromate (Na2(51)CrO4) resulted in chromium (Cr) binding to DNA. The binding of Cr to DNA was much more stable when more residual peptide/amino acids were associated with DNA. A substantial portion of the Cr bound to DNA was released by treatment with EDTA, suggesting that trivalent Cr was the major oxidation state of Cr bound to DNA. Cr(III) stimulated the formation of amino acid-DNA and protein-DNA complexes in vitro. Tyrosine and cysteine exhibited the highest activity in being complexed to DNA by Cr(III) in vitro, while histidine, methionine and threonine also exhibited more activity than any other amino acid. Similar results were found in intact cells. The activity of proteins complexed to DNA by trivalent Cr depended upon the content of these reactive amino acids. Thus, bovine serum albumin was more active than actin, which in turn was more active than histones. These and other studies presented suggested that Cr(III) was involved directly in the formation of DNA-protein complexes in intact cells, unlike other metals such as Ni(II), which are thought to form DNA-protein cross-links catalytically and not participate directly in the complex. The majority of trivalent Cr associated with DNA was bound to the phosphate backbone without exhibiting any base specificity. Collectively, these results indicate that trivalent Cr creates DNA protein crosslinks by binding with reactive amino acids (i.e. cysteine, tyrosine or histidine) and linking these to the phosphate backbone of DNA."
1516371,Salisbury et al. 2093,"Hazard Evaluation and Technical Assistance Report No. HETA-89-276-L2093, Lockheed Aeronautical Systems Company, Marietta, Georgia","In response to a request from the International Association of Machinists and Aerospace Workers, NIOSH conducted an evaluation at the Lockheed Aeronautical Systems Company, Marietta, Georgia due to concerns about health hazards from exposure to epoxy and polyurethane paints being sprayed in open areas on the C-130 aircraft assembly line. About 350 employees worked on the final assembly line. Air samples were collected to evaluate potential exposures to diisocyanates, organic vapors, and trace metals released during painting operations. Environmental sampling demonstrated minimal risk of exposure for nonpainters to organic vapors, isocyanate prepolymers, and toxic metals released into the open atmosphere during first shift painting of wing panels. Area monitors showed airborne concentrations of organic vapors and hazardous particulates which were below current occupational limits. Exposure risks to hexavalent chromium (7440473) compounds were shown for one of the painters spraying primer containing strontium-chromate (7789062). The large interior volume of the building and the rapid dispersion and upward drift of paint overspray may tend to reduce the chance of floor level exposures. The practice of spraying polyurethane when the building was mostly unoccupied should prevent new cases of respiratory sensitization to diisocyanates among the C-130 production workers. The authors recommend specific measures to reduce exposures to diisocyanates and hexavalent chromium compounds.","Hazard Evaluation and Technical Assistance Report No. HETA-89-276-L2093, Lockheed Aeronautical Systems Company, Marietta, Georgia Abs: In response to a request from the International Association of Machinists and Aerospace Workers, NIOSH conducted an evaluation at the Lockheed Aeronautical Systems Company, Marietta, Georgia due to concerns about health hazards from exposure to epoxy and polyurethane paints being sprayed in open areas on the C-130 aircraft assembly line. About 350 employees worked on the final assembly line. Air samples were collected to evaluate potential exposures to diisocyanates, organic vapors, and trace metals released during painting operations. Environmental sampling demonstrated minimal risk of exposure for nonpainters to organic vapors, isocyanate prepolymers, and toxic metals released into the open atmosphere during first shift painting of wing panels. Area monitors showed airborne concentrations of organic vapors and hazardous particulates which were below current occupational limits. Exposure risks to hexavalent chromium (7440473) compounds were shown for one of the painters spraying primer containing strontium-chromate (7789062). The large interior volume of the building and the rapid dispersion and upward drift of paint overspray may tend to reduce the chance of floor level exposures. The practice of spraying polyurethane when the building was mostly unoccupied should prevent new cases of respiratory sensitization to diisocyanates among the C-130 production workers. The authors recommend specific measures to reduce exposures to diisocyanates and hexavalent chromium compounds."
1516369,Salem and  Katz 1989,"Speciation, Bioavailability, and Systemic Distribution of Chromium from Whetlerite Dust","Exploratory studies were carried out to determine the speciation of chromium (7440473) in Whetlerite, a granular, activated carbon impregnated with compounds of copper, silver, and chromium; to determine the bioavailability of chromium from Whetlerite dust introduced into the respiratory tract of Sprague-Dawley-rats by intratracheal instillation; and to determine the speciation of the bioavailable chromium in the organs and tissues of exposed rats. The speciation and amounts of chromium in the Whetlerite dust prior to instillation were found to be 2.02 percent total chromium, 0.98 percent insoluble hexavalent chromium, 0.30 percent soluble hexavalent chromium, and 0.74 percent insoluble trivalent chromium. Test rats received a 140mg/kg dose of Whetlerite dust; control rats received the same dose of chromium free charcoal dust. Rats from both groups were sacrificed 4, 12, 24, and 48 hours after instillation and the trachea, lungs, liver, kidneys, spleen, and stomach were assessed for chromium content and speciation. Eighteen of the 28 test rats, but none of the control rats, died unexpectedly within 2 hours of dust instillation. Only trivalent chromium was found in the organs of the Whetlerite exposed rats, and no chromium was found in the control rats. Most of the chromium was found in the lungs and kidneys of the test rats. Twenty five percent of the administered dose of chromium was recovered in the lung, liver, kidney, spleen and blood 4 hours after instillation. On post instillation days two and three, 10 percent of the administered chromium dose was retained in the lungs. The copper concentrations in the organs of Whetlerite exposed rats appeared to be above the reported lethal doses by injection of soluble copper compounds to several species of laboratory animals, indicating that the unexpected deaths may have been due to the copper content of the Whetlerite.","Speciation, Bioavailability, and Systemic Distribution of Chromium from Whetlerite Dust Abs: Exploratory studies were carried out to determine the speciation of chromium (7440473) in Whetlerite, a granular, activated carbon impregnated with compounds of copper, silver, and chromium; to determine the bioavailability of chromium from Whetlerite dust introduced into the respiratory tract of Sprague-Dawley-rats by intratracheal instillation; and to determine the speciation of the bioavailable chromium in the organs and tissues of exposed rats. The speciation and amounts of chromium in the Whetlerite dust prior to instillation were found to be 2.02 percent total chromium, 0.98 percent insoluble hexavalent chromium, 0.30 percent soluble hexavalent chromium, and 0.74 percent insoluble trivalent chromium. Test rats received a 140mg/kg dose of Whetlerite dust; control rats received the same dose of chromium free charcoal dust. Rats from both groups were sacrificed 4, 12, 24, and 48 hours after instillation and the trachea, lungs, liver, kidneys, spleen, and stomach were assessed for chromium content and speciation. Eighteen of the 28 test rats, but none of the control rats, died unexpectedly within 2 hours of dust instillation. Only trivalent chromium was found in the organs of the Whetlerite exposed rats, and no chromium was found in the control rats. Most of the chromium was found in the lungs and kidneys of the test rats. Twenty five percent of the administered dose of chromium was recovered in the lung, liver, kidney, spleen and blood 4 hours after instillation. On post instillation days two and three, 10 percent of the administered chromium dose was retained in the lungs. The copper concentrations in the organs of Whetlerite exposed rats appeared to be above the reported lethal doses by injection of soluble copper compounds to several species of laboratory animals, indicating that the unexpected deaths may have been due to the copper content of the Whetlerite."
1516367,Sala et al. 1992,Oxidation of L-rhamnose and D-mannose by chromium(VI) in perchloric acid: A comparative study,"BIOSIS COPYRIGHT: BIOL ABS. The oxidation of L-rhamnose and D-mannose by Cr(VI) in perchloric acid follows the rate law: d(Cr(VI))/dt = (K0 + k1 (h0)2) K (aldose) Cr(VI))/1 + K (aldose) K = 5.40, k0 = 0.00138 M-1, k1 = 6.7e and K = 2.63, k0 = 2.51s-1 for L-rhamnose. This rate law corresponds to the reaction leading to the formation of L-1,4-rhamnonelactone and D-1,4-mannonelactone. No cleavage to carbon dioxide takes place when a 20-fold or higher excess of aldose over Cr(VI) is employed. Relative values of kinetic constants are interpreted in terms of primary hydroxyl group participation in the chromic ester formed in the first reaction step. The free radicals formed during the reaction react with Cr(VI) to yield (Cr(V). Two signals (giso = 1.977 and giso = 1.970) ascribed to intermediate Cr(V) complexes were observed by electron paramagnetic resonance (epr) of 0.25-1 N HClO4 solutions saturated with L-rhamnose and Cr2O72-. At higher pH (3-7), only the signal at g = 1.977 was detected. For D-mann","Oxidation of L-rhamnose and D-mannose by chromium(VI) in perchloric acid: A comparative study Abs: BIOSIS COPYRIGHT: BIOL ABS. The oxidation of L-rhamnose and D-mannose by Cr(VI) in perchloric acid follows the rate law: d(Cr(VI))/dt = (K0 + k1 (h0)2) K (aldose) Cr(VI))/1 + K (aldose) K = 5.40, k0 = 0.00138 M-1, k1 = 6.7e and K = 2.63, k0 = 2.51s-1 for L-rhamnose. This rate law corresponds to the reaction leading to the formation of L-1,4-rhamnonelactone and D-1,4-mannonelactone. No cleavage to carbon dioxide takes place when a 20-fold or higher excess of aldose over Cr(VI) is employed. Relative values of kinetic constants are interpreted in terms of primary hydroxyl group participation in the chromic ester formed in the first reaction step. The free radicals formed during the reaction react with Cr(VI) to yield (Cr(V). Two signals (giso = 1.977 and giso = 1.970) ascribed to intermediate Cr(V) complexes were observed by electron paramagnetic resonance (epr) of 0.25-1 N HClO4 solutions saturated with L-rhamnose and Cr2O72-. At higher pH (3-7), only the signal at g = 1.977 was detected. For D-mann"
1516365,Sahi et al. 1998,Cytogenetic response of hexavalent chromium-induced somatic cell abnormalities in Allium cepa,"BIOSIS COPYRIGHT: BIOL ABS. Hexavalent chromium present in water inhibited root growth due to its toxicity and its accumulation in roots. The Cr (VI) concentration in water samples ranged from 0.003 to 0.750 mg/l in and around the Sukinda valley, which was higher than the Government permissible limit. The Cr (VI)-containing water was utilized by local inhabitants for drinking and agricultural practices which produced increases in human health hazards and mutations or cell death in plants. The cytological effect of hexavale otic chromosomal abnormalities were more numerous and death to the cell occurred at higher concentrations. Local inhabitants were advised not to drink the Cr-contaminated water nor to eat below ground plant parts.","Cytogenetic response of hexavalent chromium-induced somatic cell abnormalities in Allium cepa Abs: BIOSIS COPYRIGHT: BIOL ABS. Hexavalent chromium present in water inhibited root growth due to its toxicity and its accumulation in roots. The Cr (VI) concentration in water samples ranged from 0.003 to 0.750 mg/l in and around the Sukinda valley, which was higher than the Government permissible limit. The Cr (VI)-containing water was utilized by local inhabitants for drinking and agricultural practices which produced increases in human health hazards and mutations or cell death in plants. The cytological effect of hexavale otic chromosomal abnormalities were more numerous and death to the cell occurred at higher concentrations. Local inhabitants were advised not to drink the Cr-contaminated water nor to eat below ground plant parts."
1516363,Sag and  Kutsal 1989,The use of zoogloea-ramigera in waste water treatment containing chromium-vi and cadmium-ii ions,Biosis copyright: biol abs. rrm wastewater treatment biotechnology industry,The use of zoogloea-ramigera in waste water treatment containing chromium-vi and cadmium-ii ions Abs: Biosis copyright: biol abs. rrm wastewater treatment biotechnology industry
1516360,Ruz et al. 1986,Flow-Injection Configurations for Chromium Speciation with a Single Spectrophotometric Detector,"1,5-Diphenylcarbazide (DPC) was employed for the simultaneous and sequential spectrophotometric determination of chromium(VI) (18540299) and total chromium (7440473) using different configurations, with one or two flow cells and spectrophotometric detection with a single beam or double beam spectrophotometer, in order to establish the most effective configuration. Chromium(III) (16065831) and chromium(VI) were distinguished by using two carrier streams, one of which contained cerium(IV) to oxidize the trivalent chromium or hexavalent chromium. Using a double beam spectrophotometer and flow cells in series, the signal provided by cell 1 was related to the concentration of chromium(VI) in the sample. When a single or double beam spectrophotometer was used for detection with splitting of the injected sample, two peaks per injected sample were obtained, their exact form depending on the detector arrangement used. Optimization of the flow injection variable was studied by the univariate method in all cases. The optimum sample volume was determined to be 207 microliters. Three reactors were kept at room temperature, whereas one reactor was maintained at 42 degrees-C to favor the oxidation of chromium(III). The DPC concentration ensuring complete dissolution of the reagent was 0.17 percent (weight/volume) in 40 percent (volume/volume) ethanol. For simultaneous determination of chromium(III) and chromium(VI), it was necessary to obtain three calibration graphs, two for chromium(VI) (one for each peak) and one for chromium(III). When using detection by a single beam spectrophotometer with a diverting valve, the optimum concentrations of DPC, oxidant, and sulfuric-acid were the same. Three calibration graphs were again needed. There were more interferences during determination of chromium(III) because of the inclusion of the oxidation step. In general, the most serious interferences were from sulfide and mercury(II) ion. Double beam detection gave the most reproducible results. The authors state that flow injection methodology has the advantages of simplicity, rapidity, and versatility. Systematic optimization of the variables results in improved sensitivity.","Flow-Injection Configurations for Chromium Speciation with a Single Spectrophotometric Detector Abs: 1,5-Diphenylcarbazide (DPC) was employed for the simultaneous and sequential spectrophotometric determination of chromium(VI) (18540299) and total chromium (7440473) using different configurations, with one or two flow cells and spectrophotometric detection with a single beam or double beam spectrophotometer, in order to establish the most effective configuration. Chromium(III) (16065831) and chromium(VI) were distinguished by using two carrier streams, one of which contained cerium(IV) to oxidize the trivalent chromium or hexavalent chromium. Using a double beam spectrophotometer and flow cells in series, the signal provided by cell 1 was related to the concentration of chromium(VI) in the sample. When a single or double beam spectrophotometer was used for detection with splitting of the injected sample, two peaks per injected sample were obtained, their exact form depending on the detector arrangement used. Optimization of the flow injection variable was studied by the univariate method in all cases. The optimum sample volume was determined to be 207 microliters. Three reactors were kept at room temperature, whereas one reactor was maintained at 42 degrees-C to favor the oxidation of chromium(III). The DPC concentration ensuring complete dissolution of the reagent was 0.17 percent (weight/volume) in 40 percent (volume/volume) ethanol. For simultaneous determination of chromium(III) and chromium(VI), it was necessary to obtain three calibration graphs, two for chromium(VI) (one for each peak) and one for chromium(III). When using detection by a single beam spectrophotometer with a diverting valve, the optimum concentrations of DPC, oxidant, and sulfuric-acid were the same. Three calibration graphs were again needed. There were more interferences during determination of chromium(III) because of the inclusion of the oxidation step. In general, the most serious interferences were from sulfide and mercury(II) ion. Double beam detection gave the most reproducible results. The authors state that flow injection methodology has the advantages of simplicity, rapidity, and versatility. Systematic optimization of the variables results in improved sensitivity."
1516357,Ruhe 1982,"Health Hazard Evaluation Report, No. HETA-81-426-1062, Xomox Corporation, Cincinnati, Ohio","A request from the safety coordinator of the Xomox Corporation (SIC-3494) Cincinnati, Ohio to determine lead (7439921) exposure in the paint spray booth at the facility was received. The study was conducted on October 14, 1981. The two paint spray operators were exposed to airborne lead in concentrations ranging from 10 to 80 micrograms per cubic meter (microg/m3) compared to an OSHA standard of 50microg/m3. These employees had blood lead concentrations below 30 micrograms per 100 milliliters (microg/100ml) of blood compared to a normal upper limit of 40microg/100ml. Analysis of personal air samples for hexavalent-chromium (7440473) ranged from less than detectable to 0.38microg/m3 compared to an OSHA standard of 100microg/m3. The operators wore NIOSH approved high efficiency air purifying respirators for airborne lead while performing their duties. Neither paint spray operator reported health problems. The author concludes that one operator was exposed to airborne concentrations of inorganic lead above recommended standards. However, blood lead values were within current guidelines for both workers.","Health Hazard Evaluation Report, No. HETA-81-426-1062, Xomox Corporation, Cincinnati, Ohio Abs: A request from the safety coordinator of the Xomox Corporation (SIC-3494) Cincinnati, Ohio to determine lead (7439921) exposure in the paint spray booth at the facility was received. The study was conducted on October 14, 1981. The two paint spray operators were exposed to airborne lead in concentrations ranging from 10 to 80 micrograms per cubic meter (microg/m3) compared to an OSHA standard of 50microg/m3. These employees had blood lead concentrations below 30 micrograms per 100 milliliters (microg/100ml) of blood compared to a normal upper limit of 40microg/100ml. Analysis of personal air samples for hexavalent-chromium (7440473) ranged from less than detectable to 0.38microg/m3 compared to an OSHA standard of 100microg/m3. The operators wore NIOSH approved high efficiency air purifying respirators for airborne lead while performing their duties. Neither paint spray operator reported health problems. The author concludes that one operator was exposed to airborne concentrations of inorganic lead above recommended standards. However, blood lead values were within current guidelines for both workers."
1516356,Ruhe 1982,"Health Hazard Evaluation Report, No. HETA-81-438-1090, Matryx Corporation, Sharonville, Ohio","AA survey of exposure to inorganic lead (7439921) and hexavalent chromium (7440473) at a paint spray booth at the Matryx Corporation (SIC-3494), Sharonville, Ohio, was conducted. The Corporation's Safety Coordinator requested the survey which was performed on October 1, and December 9, 1981. Personal samples for lead and chromium were collected and measured for the two spray painters. The face spray velocity of the paint spray booth was measured. Workers were interviewed and previously collected blood lead samples were reviewed. Operators were potentially exposed to airborne lead concentrations of 97 to 1356 micrograms per cubic meter (microg/m3), above the OSHA limit of 50microg/m3. Hexavalent chromium exposure was undetectable to 23microg/m3, above the NIOSH standard of 1microg/m3, but below the OSHA ceiling value of 100microg/m3. The average face velocity of the paint spray booth was 70 linear feet per minute. Blood lead concentrations of the workers were below 30 micrograms per 100 milliliters, and no health problems were reported. The author concludes that even though lead and chromium exposures were above recommended values, blood lead concentrations were within current criteria. He recommends respiratory protection and frequent filter changes in the paint spray booths.","Health Hazard Evaluation Report, No. HETA-81-438-1090, Matryx Corporation, Sharonville, Ohio Abs: AA survey of exposure to inorganic lead (7439921) and hexavalent chromium (7440473) at a paint spray booth at the Matryx Corporation (SIC-3494), Sharonville, Ohio, was conducted. The Corporation's Safety Coordinator requested the survey which was performed on October 1, and December 9, 1981. Personal samples for lead and chromium were collected and measured for the two spray painters. The face spray velocity of the paint spray booth was measured. Workers were interviewed and previously collected blood lead samples were reviewed. Operators were potentially exposed to airborne lead concentrations of 97 to 1356 micrograms per cubic meter (microg/m3), above the OSHA limit of 50microg/m3. Hexavalent chromium exposure was undetectable to 23microg/m3, above the NIOSH standard of 1microg/m3, but below the OSHA ceiling value of 100microg/m3. The average face velocity of the paint spray booth was 70 linear feet per minute. Blood lead concentrations of the workers were below 30 micrograms per 100 milliliters, and no health problems were reported. The author concludes that even though lead and chromium exposures were above recommended values, blood lead concentrations were within current criteria. He recommends respiratory protection and frequent filter changes in the paint spray booths."
1516355,Ruesink and  Smith 1975,"The relationship of the 96-hour LC50 to the lethal threshold concentration of hexavalent chromium, phenol, and sodium pentachlorophenate for fathead minnows (Pimephales promelas Rafinesque)","HEEP COPYRIGHT: BIOL ABS. Short-term bioassays were conducted with adult fathead minnows and hexavalent chromium, phenol and sodium pentachlorophenate at 2 temperatures to determine the relationship of the 96-h LC50 to the lethal threshold concentration. The lethal threshold concentration was less than the 96-h LC50 in 10 of 12 bioassays, was affected by temperature and was not a constant multiple of the 96-h LC50 for any of the toxicants tested.","The relationship of the 96-hour LC50 to the lethal threshold concentration of hexavalent chromium, phenol, and sodium pentachlorophenate for fathead minnows (Pimephales promelas Rafinesque) Abs: HEEP COPYRIGHT: BIOL ABS. Short-term bioassays were conducted with adult fathead minnows and hexavalent chromium, phenol and sodium pentachlorophenate at 2 temperatures to determine the relationship of the 96-h LC50 to the lethal threshold concentration. The lethal threshold concentration was less than the 96-h LC50 in 10 of 12 bioassays, was affected by temperature and was not a constant multiple of the 96-h LC50 for any of the toxicants tested."
1516354,Ruedel and  Terytze 1999,Determination of extractable chromium(VI) in soils using a photometric method,"BIOSIS COPYRIGHT: BIOL ABS. For determination of soluble Cr(VI) beside Cr(III) in soil a method was developed based on the photometric standard protocol used for determination of Cr(VI) in waters. For Cr(VI) extraction, the soil is shaken with a mixture of aluminium sulfate solution and phosphate buffer. To prevent interfering redox reactions, oxidizing compounds are reduced by adding sulfite, and afterwards reducing compounds are oxidized by hypochlorite. After reaction of Cr(VI) with 1,5-diphenylcarbazide, the photometri","Determination of extractable chromium(VI) in soils using a photometric method Abs: BIOSIS COPYRIGHT: BIOL ABS. For determination of soluble Cr(VI) beside Cr(III) in soil a method was developed based on the photometric standard protocol used for determination of Cr(VI) in waters. For Cr(VI) extraction, the soil is shaken with a mixture of aluminium sulfate solution and phosphate buffer. To prevent interfering redox reactions, oxidizing compounds are reduced by adding sulfite, and afterwards reducing compounds are oxidized by hypochlorite. After reaction of Cr(VI) with 1,5-diphenylcarbazide, the photometri"
1516351,Rowe and  Scott 1996,Removal of toxic metals from water streams by biofilm covered granular activated carbon,Biosis copyright: biol abs. rrm meeting paper klebsiella-pneumoniae-ssp-pneumoniae enterobacter-aerogenes zoogloea-ramigera biofilm biofilm covered granular activated carbon water streams toxic metal removal chromium toxic metal pollutant nickel cadmium bioprocess engineering pollution water treatment method contamination,Removal of toxic metals from water streams by biofilm covered granular activated carbon Abs: Biosis copyright: biol abs. rrm meeting paper klebsiella-pneumoniae-ssp-pneumoniae enterobacter-aerogenes zoogloea-ramigera biofilm biofilm covered granular activated carbon water streams toxic metal removal chromium toxic metal pollutant nickel cadmium bioprocess engineering pollution water treatment method contamination
1516350,Roush et al. 1964,Toxicology: Inorganic,"The toxicology of the following inorganic compounds were reviewed based on a literature survey: carbon-monoxide (CO) (630080), nitrogen-oxides, ozone (10028156), sulfur-dioxide (7446095) (SO2), silica (7631869), arsenic (7440382), cadmium (7440439), chromium (7440473), iron (7439896), lead (7439921), mercury (7439976), nickel (7440020), and selenium (7782492). It was estimated that 70 percent conversion of hemoglobin to carboxyhemoglobin by CO was required to produce death; in elderly persons a 40 percent level might be lethal. The combination of 5 percent carbon-dioxide and 95 percent oxygen was reported most effective in lowering the carboxyhemoglobin level in blood. A single exposure to 200 to 400 parts per million (ppm) of nitrogen-dioxide (10102440) found in silos was capable of inducing progressive fibrosing bronchiolitis. Mice exposed to low concentrations of ozone were more susceptible to infection. Ozone caused multiple chromosomal changes in cell cultures. Exposure to 1ppm of SO2 increased the resistance of air flow in the respiratory tract; no effect on ciliary action was expected at concentrations prevailing in the atmosphere of American cities. Silica produced an intense and specific fibrotic reaction. Arsenic had been implicated as a carcinogenic agent for a long time. Cadmium was observed to cause pulmonary irritation, pneumonia, proteinuria, and tumors. Hexavalent-chromium was found to be an occupational allergen. Calcium-ethylenediaminetetraacetic-acid (EDTA) therapy was effective in removing toxic levels of iron from animal tissues. Metaphyseal dysplasia occurred in 50 percent of children with lead poisoning. Animals fed a diet containing 1 percent lead-acetate (301042) developed tumors. Penicillamine was suggested as a chelating agent in lead poisoning therapy. The symptoms of lead poisoning were reported to occur when its concentration was above 300 milligrams/liter of urine. Porphyria was produced by several mercury compounds. Nickel was found to be a skin sensitizer and was implicated in respiratory tumors. Elemental selenium was considered nontoxic, but hydrogen-selenide (7783075) was highly toxic. Sodium-sulfate promoted urinary secretion of selenium.","Toxicology: Inorganic Abs: The toxicology of the following inorganic compounds were reviewed based on a literature survey: carbon-monoxide (CO) (630080), nitrogen-oxides, ozone (10028156), sulfur-dioxide (7446095) (SO2), silica (7631869), arsenic (7440382), cadmium (7440439), chromium (7440473), iron (7439896), lead (7439921), mercury (7439976), nickel (7440020), and selenium (7782492). It was estimated that 70 percent conversion of hemoglobin to carboxyhemoglobin by CO was required to produce death; in elderly persons a 40 percent level might be lethal. The combination of 5 percent carbon-dioxide and 95 percent oxygen was reported most effective in lowering the carboxyhemoglobin level in blood. A single exposure to 200 to 400 parts per million (ppm) of nitrogen-dioxide (10102440) found in silos was capable of inducing progressive fibrosing bronchiolitis. Mice exposed to low concentrations of ozone were more susceptible to infection. Ozone caused multiple chromosomal changes in cell cultures. Exposure to 1ppm of SO2 increased the resistance of air flow in the respiratory tract; no effect on ciliary action was expected at concentrations prevailing in the atmosphere of American cities. Silica produced an intense and specific fibrotic reaction. Arsenic had been implicated as a carcinogenic agent for a long time. Cadmium was observed to cause pulmonary irritation, pneumonia, proteinuria, and tumors. Hexavalent-chromium was found to be an occupational allergen. Calcium-ethylenediaminetetraacetic-acid (EDTA) therapy was effective in removing toxic levels of iron from animal tissues. Metaphyseal dysplasia occurred in 50 percent of children with lead poisoning. Animals fed a diet containing 1 percent lead-acetate (301042) developed tumors. Penicillamine was suggested as a chelating agent in lead poisoning therapy. The symptoms of lead poisoning were reported to occur when its concentration was above 300 milligrams/liter of urine. Porphyria was produced by several mercury compounds. Nickel was found to be a skin sensitizer and was implicated in respiratory tumors. Elemental selenium was considered nontoxic, but hydrogen-selenide (7783075) was highly toxic. Sodium-sulfate promoted urinary secretion of selenium."
1516349,Roubal and  Krivucova 1960,Hygienic Problems Connected with the Use of Tertiary Butyl-Chromate as a Passive Inhibitor of Metal Corrosion,"Experiments prompted by toxic symptoms manifested by a laboratory technician during work with (tert-butyl) chromate, revealed the presence of hexavalent chromium (7440473) at levels exceeding the maximum admissible concentrations in the atmosphere of a working environment during the impregnation of paper paraffin containing 5 percent of the chromate. Animals exposed to the chromate exhibited respiratory disorders, and skin injuries accompanied by liver disorders. Preventive measures are recommended for the paper impregnation operation. (German: English translation available)","Hygienic Problems Connected with the Use of Tertiary Butyl-Chromate as a Passive Inhibitor of Metal Corrosion Abs: Experiments prompted by toxic symptoms manifested by a laboratory technician during work with (tert-butyl) chromate, revealed the presence of hexavalent chromium (7440473) at levels exceeding the maximum admissible concentrations in the atmosphere of a working environment during the impregnation of paper paraffin containing 5 percent of the chromate. Animals exposed to the chromate exhibited respiratory disorders, and skin injuries accompanied by liver disorders. Preventive measures are recommended for the paper impregnation operation. (German: English translation available)"
1516348,Rosen 1993,PIMEX. Combined Use of Air Sampling Instruments and Video Filming: Experience and Results during Six Years of Use,"The first 6 years experience of the use of the Picture Mix Exposure (PIMEX) system for monitoring exposures to air contaminants in the workplace was discussed. The PIMEX system was designed to simultaneously measure chemical or physical agents in the breathing zone of a worker using real time monitoring instruments combined with video recording. The signals from the air monitor, which was carried in a backpack worn by the worker, were transmitted to a video mixer where they were superimposed on a video image showing the workplace and recorded on a video tape recorder for later analysis. Any type of real time monitoring instrument that produced a continuous signal with a lag time of less than 5 seconds could be used in the system. PIMEX has been used as a technique for evaluating efforts to control hexavalent chromium (7440473) fume exposures during welding operations and styrene (100425) exposures in the Swedish glass reinforced plastics industry. The recorded data were edited into short video films that have been used to train workers in work practices to avoid exposures. Films about occupational exposures in furniture manufacturing and screen printing shops, wood dust exposures occurring during furniture manufacturing, and gasoline vapor exposures at service stations have also been produced. The author notes that PIMEX can be used as a research tool for studying worker behaviors and developing control procedures.","PIMEX. Combined Use of Air Sampling Instruments and Video Filming: Experience and Results during Six Years of Use Abs: The first 6 years experience of the use of the Picture Mix Exposure (PIMEX) system for monitoring exposures to air contaminants in the workplace was discussed. The PIMEX system was designed to simultaneously measure chemical or physical agents in the breathing zone of a worker using real time monitoring instruments combined with video recording. The signals from the air monitor, which was carried in a backpack worn by the worker, were transmitted to a video mixer where they were superimposed on a video image showing the workplace and recorded on a video tape recorder for later analysis. Any type of real time monitoring instrument that produced a continuous signal with a lag time of less than 5 seconds could be used in the system. PIMEX has been used as a technique for evaluating efforts to control hexavalent chromium (7440473) fume exposures during welding operations and styrene (100425) exposures in the Swedish glass reinforced plastics industry. The recorded data were edited into short video films that have been used to train workers in work practices to avoid exposures. Films about occupational exposures in furniture manufacturing and screen printing shops, wood dust exposures occurring during furniture manufacturing, and gasoline vapor exposures at service stations have also been produced. The author notes that PIMEX can be used as a research tool for studying worker behaviors and developing control procedures."
1516347,Rose 1977,Why the Delay in Cancer-Protection Standards?,"The problem of the time lag between the development of recommendations for standards and completion of the standard is discussed. In five years the Department of Health, Education and Welfare has submitted more than 250 recommendations to OSHA, which has developed 17 standards. As the list of known carcinogens continues to grow, NIOSH will recommend that OSHA implement emergency temporary standards immediately for benzene (71432), 4,4'-methylenebis-o-2-chlorobenzenamine (101144), and certain hexavalent chromium (7440473) compounds. The toxicity of these substances is known, and recommendations for standards have been in OSHA's possession for periods of up to three years without any action being taken; meanwhile workers continue to be exposed.","Why the Delay in Cancer-Protection Standards? Abs: The problem of the time lag between the development of recommendations for standards and completion of the standard is discussed. In five years the Department of Health, Education and Welfare has submitted more than 250 recommendations to OSHA, which has developed 17 standards. As the list of known carcinogens continues to grow, NIOSH will recommend that OSHA implement emergency temporary standards immediately for benzene (71432), 4,4'-methylenebis-o-2-chlorobenzenamine (101144), and certain hexavalent chromium (7440473) compounds. The toxicity of these substances is known, and recommendations for standards have been in OSHA's possession for periods of up to three years without any action being taken; meanwhile workers continue to be exposed."
1516346,Romano and  Krol 1992,Regulated methods for ion analysis,Biosis copyright: biol abs. rrm nitrites nitrates drinking water contamination ion chromatography analytical method epa usa,Regulated methods for ion analysis Abs: Biosis copyright: biol abs. rrm nitrites nitrates drinking water contamination ion chromatography analytical method epa usa
1516343,Rodriguez et al. 1996,Oxidative dna damage patterns induced in vivo by h-2o-2 and in vitro by cuii feiii or crvi-ascorbate-h-2o-2 treatment,Biosis copyright: biol abs. rrm meeting abstract human tumor suppressor gene reactive oxygen species hydrogen peroxide copperii ironiii chromiumvi mutagen,Oxidative dna damage patterns induced in vivo by h-2o-2 and in vitro by cuii feiii or crvi-ascorbate-h-2o-2 treatment Abs: Biosis copyright: biol abs. rrm meeting abstract human tumor suppressor gene reactive oxygen species hydrogen peroxide copperii ironiii chromiumvi mutagen
1516342,Robinson et al. 1988,Effects of culture conditions on the sensitivity of a phoxocephalid amphipod rhepoxynius-abronius to cadmium in sediment,Biosis copyright: biol abs. rrm pollution adult juvenile seawater toxicity test organism,Effects of culture conditions on the sensitivity of a phoxocephalid amphipod rhepoxynius-abronius to cadmium in sediment Abs: Biosis copyright: biol abs. rrm pollution adult juvenile seawater toxicity test organism
1516341,Rinehart and  Gad 1986,Current Concepts in Occupational Health: Metals Chromium,"A brief overview of historical findings was presented, and toxicity, chemistry, physical properties, and biological handling of chromium (7440473) compounds were discussed in order to define the potential hazards in the workplace. Factors which may affect the toxicity of chromium includes valence state, organic complex form, ionic species of chromium(VI), solubility, and particle size. For dermal exposures, effects of chromium are related to the acidity and oxidizing potential of the compound or mixture; chromium(VI) compounds also may cause allergic dermatitis or sensitization. Inhalation exposure to chromium(VI) compounds have been found to act mainly on the respiratory tract. Chromium compounds have been found to have mutagenic and carcinogenic properties, and to be toxic after acute exposure. Studies have indicated that toxicity and carcinogenicity are dose related. Blood analysis is not very useful for biological monitoring; urinary monitoring has been more successful. The authors conclude that technology and good industrial hygiene practice have already controlled or can prevent serious problems arising due to workplace exposure, either by dermal contact or inhalation. KW - DCN-151611","Current Concepts in Occupational Health: Metals Chromium Abs: A brief overview of historical findings was presented, and toxicity, chemistry, physical properties, and biological handling of chromium (7440473) compounds were discussed in order to define the potential hazards in the workplace. Factors which may affect the toxicity of chromium includes valence state, organic complex form, ionic species of chromium(VI), solubility, and particle size. For dermal exposures, effects of chromium are related to the acidity and oxidizing potential of the compound or mixture; chromium(VI) compounds also may cause allergic dermatitis or sensitization. Inhalation exposure to chromium(VI) compounds have been found to act mainly on the respiratory tract. Chromium compounds have been found to have mutagenic and carcinogenic properties, and to be toxic after acute exposure. Studies have indicated that toxicity and carcinogenicity are dose related. Blood analysis is not very useful for biological monitoring; urinary monitoring has been more successful. The authors conclude that technology and good industrial hygiene practice have already controlled or can prevent serious problems arising due to workplace exposure, either by dermal contact or inhalation. KW - DCN-151611"
1516340,Rinehart et al. 1997,Chromium leaching vs. oxidation state for a contaminated solidified/stabilized soil,"BIOSIS COPYRIGHT: BIOL ABS. The toxicity, solubility, and mobility of chromium in soil are strongly dependent upon its oxidation state. Solidification/stabilization (S) is a potential method for preventing Cr leaching from contaminated soil. We evaluated the leaching behavior of untreated and solidified/stabilized chromium contaminated soil samples obtained from two locations at a military facility in Louisiana. The leaching of chromium, as measured by the Toxicity Characteristic Leaching Procedure (TCLP), was expected to be dependent upon the chromium oxidation state. The pH, cation exchange capacity and particle size distribution were obtained for each sample and portions of each sample were solidified with Type I Portland cement. The oxidation state of chromium was determined by X-ray absorption spectroscopy (XAS). The sample from Site 1 contained 478 mg kg-1 total chromium while the sample from Site 2 contained 1272 mg kg-1 total Cr. The TCLP chromium concentration for Site 1 untreated soil wa","Chromium leaching vs. oxidation state for a contaminated solidified/stabilized soil Abs: BIOSIS COPYRIGHT: BIOL ABS. The toxicity, solubility, and mobility of chromium in soil are strongly dependent upon its oxidation state. Solidification/stabilization (S) is a potential method for preventing Cr leaching from contaminated soil. We evaluated the leaching behavior of untreated and solidified/stabilized chromium contaminated soil samples obtained from two locations at a military facility in Louisiana. The leaching of chromium, as measured by the Toxicity Characteristic Leaching Procedure (TCLP), was expected to be dependent upon the chromium oxidation state. The pH, cation exchange capacity and particle size distribution were obtained for each sample and portions of each sample were solidified with Type I Portland cement. The oxidation state of chromium was determined by X-ray absorption spectroscopy (XAS). The sample from Site 1 contained 478 mg kg-1 total chromium while the sample from Site 2 contained 1272 mg kg-1 total Cr. The TCLP chromium concentration for Site 1 untreated soil wa"
1516338,Riedel 1984,Influence of salinity and sulfate on the toxicity of chromium(VI) to the estuarine diatom Thalassiosira pseudonana,HEEP COPYRIGHT: BIOL ABS. The acute toxicity of Cr(VI) to the diatom pseudonana (Hasle and Heimdal) clone 3H was determined in artificial media of 3.2 and 0.32 ppt salinity and with variations of sulfate concentration in the media independent of salinity. Inhibitory concentrations of Cr(VI) ranged from 6.6 muM for growth rate and 4.9 muM for cell yield at 3.2 ppt salinity and 2.8 mM sulfate to 0.04 muM for growth rate and 0.02 muM for cell yield at 0.32 ppt salinity and 0.019 mM sulfate. The inhibition by Cr(VI) was a function of the ratio of Cr(VI) to sulfate. Inhibition occurred when this ratio exceeded about 500:1. The mechanism for the toxicity of Cr(VI) to diatoms and perhaps other aquatic organisms involves a site at which sulfate and chromate compete.,Influence of salinity and sulfate on the toxicity of chromium(VI) to the estuarine diatom Thalassiosira pseudonana Abs: HEEP COPYRIGHT: BIOL ABS. The acute toxicity of Cr(VI) to the diatom pseudonana (Hasle and Heimdal) clone 3H was determined in artificial media of 3.2 and 0.32 ppt salinity and with variations of sulfate concentration in the media independent of salinity. Inhibitory concentrations of Cr(VI) ranged from 6.6 muM for growth rate and 4.9 muM for cell yield at 3.2 ppt salinity and 2.8 mM sulfate to 0.04 muM for growth rate and 0.02 muM for cell yield at 0.32 ppt salinity and 0.019 mM sulfate. The inhibition by Cr(VI) was a function of the ratio of Cr(VI) to sulfate. Inhibition occurred when this ratio exceeded about 500:1. The mechanism for the toxicity of Cr(VI) to diatoms and perhaps other aquatic organisms involves a site at which sulfate and chromate compete.
1516334,Reich and  O'Hagen 1990,Chemicals and allied products,Biosis copyright: biol abs. rrm review waste management industry chemical industry government regulations water pollution control biological treatment physical treatment chemical treatment sludge treatment sludge disposal,Chemicals and allied products Abs: Biosis copyright: biol abs. rrm review waste management industry chemical industry government regulations water pollution control biological treatment physical treatment chemical treatment sludge treatment sludge disposal
1516333,Rege et al. 1997,Bacterial reduction of hexavalent chromium by Enterobacter cloacae strain HO1 grown on sucrose,"BIOSIS COPYRIGHT: BIOL ABS. Chromium(VI) was reduced by Enterobacter cloacae strain HO1 grown with sucrose as a carbon source and nitrate as the initial terminal electron acceptor. Under excess substrate conditions, the Cr(VI) concentration, initially at 5 and 10 mg/l, was reduced to less than 100 mug/l.","Bacterial reduction of hexavalent chromium by Enterobacter cloacae strain HO1 grown on sucrose Abs: BIOSIS COPYRIGHT: BIOL ABS. Chromium(VI) was reduced by Enterobacter cloacae strain HO1 grown with sucrose as a carbon source and nitrate as the initial terminal electron acceptor. Under excess substrate conditions, the Cr(VI) concentration, initially at 5 and 10 mg/l, was reduced to less than 100 mug/l."
1516331,Reddy and  Chinthamreddy 1999,Electrokinetic remediation of heavy metal-contaminated soils under reducing environments,"BIOSIS COPYRIGHT: BIOL ABS. This paper describes the migration of hexavalent chromium, Cr(VI), nickel, Ni(II), and cadmium, Cd(II), in clayey soils that contain different reducing agents under an induced electric potential. Bench-scale electrokinetic experiments were conducted using two different clays, kaolin and glacial till, both with and without a reducing agent. The reducing agent used was either humic acid, ferrous iron, or sulfide, in a concentration of 1000 mg/kg. These soils were then spiked with Cr(VI), Ni(II), a ccurred in the presence of sulfides, while the minimum reduction occurred in the presence of humic acid. The concentration profiles in both soils following electrokinetic treatment showed that Cr(VI) migration was retarded significantly in the presence of sulfides due both to the reduction of Cr(VI) to Cr(III) as well as an increase in soil pH. This low migration of chromium is attributed to: (1) migration of Cr(VI) and the reduced Cr(III) fraction in opposite directions, (2) low","Electrokinetic remediation of heavy metal-contaminated soils under reducing environments Abs: BIOSIS COPYRIGHT: BIOL ABS. This paper describes the migration of hexavalent chromium, Cr(VI), nickel, Ni(II), and cadmium, Cd(II), in clayey soils that contain different reducing agents under an induced electric potential. Bench-scale electrokinetic experiments were conducted using two different clays, kaolin and glacial till, both with and without a reducing agent. The reducing agent used was either humic acid, ferrous iron, or sulfide, in a concentration of 1000 mg/kg. These soils were then spiked with Cr(VI), Ni(II), a ccurred in the presence of sulfides, while the minimum reduction occurred in the presence of humic acid. The concentration profiles in both soils following electrokinetic treatment showed that Cr(VI) migration was retarded significantly in the presence of sulfides due both to the reduction of Cr(VI) to Cr(III) as well as an increase in soil pH. This low migration of chromium is attributed to: (1) migration of Cr(VI) and the reduced Cr(III) fraction in opposite directions, (2) low"
1516330,Razek et al. 1999,Selective measurement of chromium(VI) by fluorescence quenching of ruthenium,"BIOSIS COPYRIGHT: BIOL ABS. A flow injection method is described for the selective measurement of chromium(VI) in aqueous solutions. This method is based on the dynamic quenching of ruthenium(II) fluorescence. The detection limit is 0.43 ppm and 40 samples can be analyzed per hour. Selectivity is demonstrated over ferrous, nickel, cupric and zinc cations and no effect is observed from sulfate, chloride, borate and phosphate. Some interference quenching was measured for cyanide and nitrate, but the method is more responsive to chromium(VI) by factors of 10.2 and 82, respectively. The effects of solution pH, carrier stream flow rate and ruthenium concentration are demonstrated. Results indicate the method is suitable for measuring chromium(VI) in effluents from electroplating baths.","Selective measurement of chromium(VI) by fluorescence quenching of ruthenium Abs: BIOSIS COPYRIGHT: BIOL ABS. A flow injection method is described for the selective measurement of chromium(VI) in aqueous solutions. This method is based on the dynamic quenching of ruthenium(II) fluorescence. The detection limit is 0.43 ppm and 40 samples can be analyzed per hour. Selectivity is demonstrated over ferrous, nickel, cupric and zinc cations and no effect is observed from sulfate, chloride, borate and phosphate. Some interference quenching was measured for cyanide and nitrate, but the method is more responsive to chromium(VI) by factors of 10.2 and 82, respectively. The effects of solution pH, carrier stream flow rate and ruthenium concentration are demonstrated. Results indicate the method is suitable for measuring chromium(VI) in effluents from electroplating baths."
1516329,Raskin et al. 1994,Bioconcentration of heavy metals by plants,Biosis copyright: biol abs. rrm literature review plant biotechnology root shoot soils water pollution metal accumulation translocation phytoremediation,Bioconcentration of heavy metals by plants Abs: Biosis copyright: biol abs. rrm literature review plant biotechnology root shoot soils water pollution metal accumulation translocation phytoremediation
1516328,Raskin 1996,Plant genetic engineering may help with environmental cleanup,Biosis copyright: biol abs. rrm journal article arabidopsis thalassiosira-weissflogii mercury breathing plant toxic metal uptake phytoremediation,Plant genetic engineering may help with environmental cleanup Abs: Biosis copyright: biol abs. rrm journal article arabidopsis thalassiosira-weissflogii mercury breathing plant toxic metal uptake phytoremediation
1516324,Raji and  Anirudhan 1998,Batch Cr(VI) removal by polyacrylamide-grafted sawdust: Kinetics and thermodynamics,"BIOSIS COPYRIGHT: BIOL ABS. Batch sorption studies have been carried out to determine the effect of adsorbent dose, initial sorbate concentration and pH on the adsorption of Cr(VI) on polymer-grafted sawdust. The process was found to be pH, temperature and concentration dependent. An empirical relationship has been obtained to predict the percentage Cr(VI) removal at any time for known values of sorbent and initial sorbate concentration under observed test conditions. The effect of diverse ions has been studied and it is found that there is very little effect on the sorption of Cr(VI). The process was found to be exothermic with a maximum adsorption of 91.0% at 30êC for an initial concentration of 100 mg l-1 at pH 3. The process follows first-order kinetics and the data fits the Freundlich adsorption isotherm. Thermodynamic parameters were also evaluated. Desorption studies confirmed that adsorbent can be effectively regenerated using 0.2 M NaOH and 0.5 M NaCl and can then be reused.","Batch Cr(VI) removal by polyacrylamide-grafted sawdust: Kinetics and thermodynamics Abs: BIOSIS COPYRIGHT: BIOL ABS. Batch sorption studies have been carried out to determine the effect of adsorbent dose, initial sorbate concentration and pH on the adsorption of Cr(VI) on polymer-grafted sawdust. The process was found to be pH, temperature and concentration dependent. An empirical relationship has been obtained to predict the percentage Cr(VI) removal at any time for known values of sorbent and initial sorbate concentration under observed test conditions. The effect of diverse ions has been studied and it is found that there is very little effect on the sorption of Cr(VI). The process was found to be exothermic with a maximum adsorption of 91.0% at 30êC for an initial concentration of 100 mg l-1 at pH 3. The process follows first-order kinetics and the data fits the Freundlich adsorption isotherm. Thermodynamic parameters were also evaluated. Desorption studies confirmed that adsorbent can be effectively regenerated using 0.2 M NaOH and 0.5 M NaCl and can then be reused."
1516321,Rai and  Kumar 1999,Treatment of chromium bearing waste water by adsorbtion on brick kiln ash and fly ash,"BIOSIS COPYRIGHT: BIOL ABS. Suitablity of brick kiln ash and fly ash for removing chromium (VI) from waste water has been investigated. Both adsorbents exhibited fairly good sorption potential for chromiun (VI) with a maximum at pH 1.3. Effects of concentration of Cr (VI) (10.0 -50 mg), particle size (124-853 mum), rpm (100- 200 s-1) and temperature (25-50êC) have been studied.","Treatment of chromium bearing waste water by adsorbtion on brick kiln ash and fly ash Abs: BIOSIS COPYRIGHT: BIOL ABS. Suitablity of brick kiln ash and fly ash for removing chromium (VI) from waste water has been investigated. Both adsorbents exhibited fairly good sorption potential for chromiun (VI) with a maximum at pH 1.3. Effects of concentration of Cr (VI) (10.0 -50 mg), particle size (124-853 mum), rpm (100- 200 s-1) and temperature (25-50êC) have been studied."
1516320,Quiros et al. 1992,Crystal structure and EPR spectrum of bispyridinium bis(citrato)chromium(III) tetrahydrate,"BIOSIS COPYRIGHT: BIOL ABS. Citric acid reacts with chromium(VI) in aqueous solution leading to the formation of chromium(V), easily detectable by EPR. However, the redox reaction goes further with the formation of a chromium(III) citrate complex. This has been crystallized as the pyridinium salt and analysed by EPR and X-ray diffraction. The structure contains discrete Cr(Cit)22- units, in which the chromium atom is octahedrally coordinated by two tridentate citrate anions. The anions and the solvate water molecules are linked by an extensive set of hydrogen bonds. The X-band and Q-band EPR spectra are well resolved, showing a large and highly anisotropic zero-field splitting.","Crystal structure and EPR spectrum of bispyridinium bis(citrato)chromium(III) tetrahydrate Abs: BIOSIS COPYRIGHT: BIOL ABS. Citric acid reacts with chromium(VI) in aqueous solution leading to the formation of chromium(V), easily detectable by EPR. However, the redox reaction goes further with the formation of a chromium(III) citrate complex. This has been crystallized as the pyridinium salt and analysed by EPR and X-ray diffraction. The structure contains discrete Cr(Cit)22- units, in which the chromium atom is octahedrally coordinated by two tridentate citrate anions. The anions and the solvate water molecules are linked by an extensive set of hydrogen bonds. The X-band and Q-band EPR spectra are well resolved, showing a large and highly anisotropic zero-field splitting."
1516318,Quevauviller 1996,CRMs for quality control of determinations of chemical forms of elements in support of EU legislation,"BIOSIS COPYRIGHT: BIOL ABS. The concern for the control of toxic chemical forms of elements in the environment is reflected by an increasing number of analyses performed by research and routine laboratories. The European Commission has recognised the need to include some of these species in the list of dangerous substances to be monitored, e.g. in the marine environment or in groundwater. However, in most cases, the specifications are far from being sufficient in respect to the chemical forms of the element to be determined. Furthermore, these determinations are in most cases based on multi-step analytical techniques which are often prone to errors (e.g. at the extraction, derivatization or separation steps). Certified reference materials (CRMs) certified for their content in chemical forms of elements are, therefore, necessary to ensure the accuracy of these measurements and hence the respect of the regulations. However, the lack of CRMs for speciation analysis hampers the quality control of det","CRMs for quality control of determinations of chemical forms of elements in support of EU legislation Abs: BIOSIS COPYRIGHT: BIOL ABS. The concern for the control of toxic chemical forms of elements in the environment is reflected by an increasing number of analyses performed by research and routine laboratories. The European Commission has recognised the need to include some of these species in the list of dangerous substances to be monitored, e.g. in the marine environment or in groundwater. However, in most cases, the specifications are far from being sufficient in respect to the chemical forms of the element to be determined. Furthermore, these determinations are in most cases based on multi-step analytical techniques which are often prone to errors (e.g. at the extraction, derivatization or separation steps). Certified reference materials (CRMs) certified for their content in chemical forms of elements are, therefore, necessary to ensure the accuracy of these measurements and hence the respect of the regulations. However, the lack of CRMs for speciation analysis hampers the quality control of det"
1516317,Qin and  Liu 1995,Chemiluminescence flow system for the monitoring of chromium(VI) in water. AU - ZHANG Z,"BIOSIS COPYRIGHT: BIOL ABS. A novel chemiluminescence(CL) system has been developed for determining chromium(VI) in water. The analytical reagents involved in the CL reaction, including luminol and hexacyanoferrate(II) were both immobilized on an anion exchange resin column. While a volume of sodium phosphate was passed through the column, these two reagents were eluted from the resins and then mixed with a chromium(VI) stream containing hydrochloric acid. By the fast oxidation reaction between chromium(VI) and hexacyanoferrate(II), hexacyanoferrate(III) was generated, which then reacted with luminol in alkaline aqueous solution to produce CL. The CL emission intensity was correlated with the chromium(VI) concentration in the range 4 1 chromium(VI). Interfering metal ions present in water were effectively separated by a pre-column cation exchanger. A complete analysis, including sampling and washing, could be performed in 1 min with a relative standard deviation of less than 5%. The system was st","Chemiluminescence flow system for the monitoring of chromium(VI) in water. AU - ZHANG Z Abs: BIOSIS COPYRIGHT: BIOL ABS. A novel chemiluminescence(CL) system has been developed for determining chromium(VI) in water. The analytical reagents involved in the CL reaction, including luminol and hexacyanoferrate(II) were both immobilized on an anion exchange resin column. While a volume of sodium phosphate was passed through the column, these two reagents were eluted from the resins and then mixed with a chromium(VI) stream containing hydrochloric acid. By the fast oxidation reaction between chromium(VI) and hexacyanoferrate(II), hexacyanoferrate(III) was generated, which then reacted with luminol in alkaline aqueous solution to produce CL. The CL emission intensity was correlated with the chromium(VI) concentration in the range 4 1 chromium(VI). Interfering metal ions present in water were effectively separated by a pre-column cation exchanger. A complete analysis, including sampling and washing, could be performed in 1 min with a relative standard deviation of less than 5%. The system was st"
1516316,Qazi et al. 1997,Cultivation of chromium-tolerant ciliate protozoans from industrial effluents of tanneries,"BIOSIS COPYRIGHT: BIOL ABS. Effluents from tanneries or Kasur area have been round to harbor protozoan, especially ciliates. They were isolated mechanically and inoculated into various media, containing antibiotic Gentamicin, to attain axenic culture. It was noted that 1% milk solution supported the optimum growth of a protozoan, whereas, yeast extract, meet extract, peptone, Chalkley's medium (rice) etc. did not give comparable results. The free living ciliate could tolerate Cr(VI) up to 7 mug/ml of the medium. These results make a foundation for further research work, intended to utilize microorganisms in the industrial-waste management strategies.","Cultivation of chromium-tolerant ciliate protozoans from industrial effluents of tanneries Abs: BIOSIS COPYRIGHT: BIOL ABS. Effluents from tanneries or Kasur area have been round to harbor protozoan, especially ciliates. They were isolated mechanically and inoculated into various media, containing antibiotic Gentamicin, to attain axenic culture. It was noted that 1% milk solution supported the optimum growth of a protozoan, whereas, yeast extract, meet extract, peptone, Chalkley's medium (rice) etc. did not give comparable results. The free living ciliate could tolerate Cr(VI) up to 7 mug/ml of the medium. These results make a foundation for further research work, intended to utilize microorganisms in the industrial-waste management strategies."
1516310,Pryor 1980,"Health Hazard Evaluation Determination Report, No. HHE-78-79-736, Cissell Manufacturing Company, Louisville, Kentucky","Environmental and personal air samples were analyzed for the presence of ozone (10028156), fluorides, nitrogen-dioxide (10102440), iron-oxide (1309371), manganese (7439965), chromium (7440473), total fume, naphtha (8030306), isobutyl-isobutyrate (97858), methyl-n-butyl ketone (591786), isobutyl-acetate (110190), isobutyl-alcohol (78831), toluene (108883), xylene (1330207), hydrochloric-acid (7647010), hexavalent-chromium (7440473), cadmium (7440439), cyanide (57125), 1,1,1-trichloroethane (71556), and asbestos (1332214) at the Cissell Manufacturing Company in Louisville, Kentucky, a manufacturer of laundry and dry cleaning space equipment and pressing machines for commercial and industrial use (SIC-3582), during July 1978 and January 1979. An evaluation request came from an authorized representative of an unspecified number of employees. Only concentrations of asbestos, ranging from 0.19 to 0.30 fibers per cubic centimeter, exceeded the recommended exposure limit of 0.1 fibers per cubic centimeter. Inadequate ventilation and work practices also were noted. The authors conclude that a potential health hazard did exist for workers exposed to asbestos. They recommend measures to reduce employee asbestos exposures, improve exhaust ventilation and institute better work practices.","Health Hazard Evaluation Determination Report, No. HHE-78-79-736, Cissell Manufacturing Company, Louisville, Kentucky Abs: Environmental and personal air samples were analyzed for the presence of ozone (10028156), fluorides, nitrogen-dioxide (10102440), iron-oxide (1309371), manganese (7439965), chromium (7440473), total fume, naphtha (8030306), isobutyl-isobutyrate (97858), methyl-n-butyl ketone (591786), isobutyl-acetate (110190), isobutyl-alcohol (78831), toluene (108883), xylene (1330207), hydrochloric-acid (7647010), hexavalent-chromium (7440473), cadmium (7440439), cyanide (57125), 1,1,1-trichloroethane (71556), and asbestos (1332214) at the Cissell Manufacturing Company in Louisville, Kentucky, a manufacturer of laundry and dry cleaning space equipment and pressing machines for commercial and industrial use (SIC-3582), during July 1978 and January 1979. An evaluation request came from an authorized representative of an unspecified number of employees. Only concentrations of asbestos, ranging from 0.19 to 0.30 fibers per cubic centimeter, exceeded the recommended exposure limit of 0.1 fibers per cubic centimeter. Inadequate ventilation and work practices also were noted. The authors conclude that a potential health hazard did exist for workers exposed to asbestos. They recommend measures to reduce employee asbestos exposures, improve exhaust ventilation and institute better work practices."
1516309,Prokisch et al. 1997,Speciation of chromium from industrial wastes and incinerated sludges,"BIOSIS COPYRIGHT: BIOL ABS. In this study, the Cr(III) and Cr(VI) contents of seven international standards, wastes, incinerated wastes and ash samples were measured with a simply hyphenated system. The Cr(III) and Cr(VI) content was measured using an on-line method, which contained an acid-activated aluminium oxide filled microcolumn that was developed especially for the study and an inductively coupled plasma atomic emission spectrometer. The sample introduction and the steps in on-line measurement were controlled by an autosampling program. For lower chromate concentrations, a similar, but off-line separation method was applied with an aluminium-oxide filled solid-phase extraction column and a graphite furnace atomic absorption spectrometer. Acid-activated aluminium oxide adsorbs the Cr(VI) in the pH 2-7 range, but does not adsorb the Cr(III). The adsorbed Cr(VI) can be eluted with strong acid. The changes in chromium forms were studied in the waste burning process as well. In our incineration","Speciation of chromium from industrial wastes and incinerated sludges Abs: BIOSIS COPYRIGHT: BIOL ABS. In this study, the Cr(III) and Cr(VI) contents of seven international standards, wastes, incinerated wastes and ash samples were measured with a simply hyphenated system. The Cr(III) and Cr(VI) content was measured using an on-line method, which contained an acid-activated aluminium oxide filled microcolumn that was developed especially for the study and an inductively coupled plasma atomic emission spectrometer. The sample introduction and the steps in on-line measurement were controlled by an autosampling program. For lower chromate concentrations, a similar, but off-line separation method was applied with an aluminium-oxide filled solid-phase extraction column and a graphite furnace atomic absorption spectrometer. Acid-activated aluminium oxide adsorbs the Cr(VI) in the pH 2-7 range, but does not adsorb the Cr(III). The adsorbed Cr(VI) can be eluted with strong acid. The changes in chromium forms were studied in the waste burning process as well. In our incineration"
1516307,Pretty et al. 1994,Determination of chromiumvi and vanadium v using an on-line anodic stripping voltammetry flow cell with detection by inductively coupled plasma mass spectrometry,Biosis copyright: biol abs. rrm research article carcinogen analytical method,Determination of chromiumvi and vanadium v using an on-line anodic stripping voltammetry flow cell with detection by inductively coupled plasma mass spectrometry Abs: Biosis copyright: biol abs. rrm research article carcinogen analytical method
1516306,Pratt et al. 1997,Products of chromate reduction on proposed subsurface remediation material,"BIOSIS COPYRIGHT: BIOL ABS. Recent studies have shown promising results for subsurface remediation of dissolved chromate using permeable-reactive redox walls. Chromate reduction in the presence of iron filings and quartz grains was studied to determine the fate of reduced chromium in proposed wall material. Using a flow-through column apparatus, iron filings mixed with quartz grains were reacted with solutions that contained about 20 mg dissolved Cr(VI). Reacted iron filings developed coatings comprised of goethite with chromium concentrated in the outermost edges. Surface analysis showed all detectable chromium occurred as Cr(III) species. In addition, in regions of increased chromium concentration, goethite acquired chemical and structural characteristics similar to Fe2O3 and Cr2O3. Results of the study show that complete reduction of Cr(VI) to Cr(III) occurred and that Cr(III) was incorporated into sparingly soluble solid species.","Products of chromate reduction on proposed subsurface remediation material Abs: BIOSIS COPYRIGHT: BIOL ABS. Recent studies have shown promising results for subsurface remediation of dissolved chromate using permeable-reactive redox walls. Chromate reduction in the presence of iron filings and quartz grains was studied to determine the fate of reduced chromium in proposed wall material. Using a flow-through column apparatus, iron filings mixed with quartz grains were reacted with solutions that contained about 20 mg dissolved Cr(VI). Reacted iron filings developed coatings comprised of goethite with chromium concentrated in the outermost edges. Surface analysis showed all detectable chromium occurred as Cr(III) species. In addition, in regions of increased chromium concentration, goethite acquired chemical and structural characteristics similar to Fe2O3 and Cr2O3. Results of the study show that complete reduction of Cr(VI) to Cr(III) occurred and that Cr(III) was incorporated into sparingly soluble solid species."
1516305,Prather 1981,"Industrial hygiene evaluation aircraft painting facility, bldg 692, mcclellan afb, california","HMTC This report presents the results of an industrial hygiene evaluation of the hexavalent chromium (CrVI) and diisocyanate levels generated during spray painting operations in the aircraft painting facility, Bldg 692, McClellan AFB, California. Building 692 is a large hangar-type facility specifically designed for spray painting aircraft. The building has vertical downdraft ventilation with air being supplied through numerous ceiling diffusers and exhausted through floor grills. Personal Time-Weighted Average (TWA) and process samples were collected for the painters and helpers involved with typical radome, aircraft, and van painting operations which are concurrently done in the facility. Area samples were also collected to determine if hazardous levels of CrVI or diisocyanates migrated throughout the facility. Approximately 500 isocyanate and 325 chromate samples were taken during the two-week survey in August 1980. The area samples clearly demonstrated that hazardous levels were not migrating throughout the building. Only minor levels of toluene diisocyanate (TDI) were observed in the radome spray painting. However, exposures frequently exceeding the standards for unprotected workers were observed in the immediate work area of the van and aircraft painting operations. The adequacy of various respirators is discussed and recommendations are made for practically eliminating the potential exposures. (Author Abstract)","Industrial hygiene evaluation aircraft painting facility, bldg 692, mcclellan afb, california Abs: HMTC This report presents the results of an industrial hygiene evaluation of the hexavalent chromium (CrVI) and diisocyanate levels generated during spray painting operations in the aircraft painting facility, Bldg 692, McClellan AFB, California. Building 692 is a large hangar-type facility specifically designed for spray painting aircraft. The building has vertical downdraft ventilation with air being supplied through numerous ceiling diffusers and exhausted through floor grills. Personal Time-Weighted Average (TWA) and process samples were collected for the painters and helpers involved with typical radome, aircraft, and van painting operations which are concurrently done in the facility. Area samples were also collected to determine if hazardous levels of CrVI or diisocyanates migrated throughout the facility. Approximately 500 isocyanate and 325 chromate samples were taken during the two-week survey in August 1980. The area samples clearly demonstrated that hazardous levels were not migrating throughout the building. Only minor levels of toluene diisocyanate (TDI) were observed in the radome spray painting. However, exposures frequently exceeding the standards for unprotected workers were observed in the immediate work area of the van and aircraft painting operations. The adequacy of various respirators is discussed and recommendations are made for practically eliminating the potential exposures. (Author Abstract)"
1516303,Prakasham et al. 1999,Biosorption of chromium VI by free and immobilized Rhizopus arrhizus,BIOSIS COPYRIGHT: BIOL ABS. Biosorption of chromium (VI) was studied by using non-living free and immobilized biomass of Rhizopus arrhizus at pH 2. A biphasic chromium adsorption pattern was observed in all experimental conditions. Chromium removal rate was slightly more in free biomass conditions over immobilized state. Stirred tank reactor studies indicated maximum chromium biosorption at 100 rpm and at 1:10 biomass-liquid ratio. Fluidized bed reactor is more efficient in chromium removal over stirred tank reactor. Immobilization of biomaterial has a little effect on chromium biosorption by this R. arrhizus biomass.,Biosorption of chromium VI by free and immobilized Rhizopus arrhizus Abs: BIOSIS COPYRIGHT: BIOL ABS. Biosorption of chromium (VI) was studied by using non-living free and immobilized biomass of Rhizopus arrhizus at pH 2. A biphasic chromium adsorption pattern was observed in all experimental conditions. Chromium removal rate was slightly more in free biomass conditions over immobilized state. Stirred tank reactor studies indicated maximum chromium biosorption at 100 rpm and at 1:10 biomass-liquid ratio. Fluidized bed reactor is more efficient in chromium removal over stirred tank reactor. Immobilization of biomaterial has a little effect on chromium biosorption by this R. arrhizus biomass.
1516302,Prakash and  Chand 1987,Chromium removal by sawdust,Biosis copyright: biol abs. rrm heavy metal pollution,Chromium removal by sawdust Abs: Biosis copyright: biol abs. rrm heavy metal pollution
1516300,Powell et al. 1995,Coupled iron corrosion and chromate reduction: Mechanisms for subsurface remediation,"BIOSIS COPYRIGHT: BIOL ABS. The reduction of chromium from the Cr(VI) to the Cr(III) state by the presence of elemental, or zero-oxidation-state, iron metal was studied to evaluate the feasibility of such a process for subsurface chromate remediation. Reactions were studied in systems of natural aquifer materials with varying geochemistry. Different forms of iron metal had significantly different abilities to reduce chromate, ranging from extremely rapid to essentially no effect. Impure, partially oxidized iron was most effective, with iron quantity being the most important rate factor, followed by aquifer material type and solid:solution ratio. Evidence for chromium-iron hydroxide solid solution (Crx,Fe1-x)(OH)3(SS) formation was obtained by electron probe microanalysis. A cyclic, multiple reaction electrochemical corrosion mechanism, enhanced by the development of an electrical double-layer analogue, is proposed to explain the differing iron reactivities and aquifer material effects","Coupled iron corrosion and chromate reduction: Mechanisms for subsurface remediation Abs: BIOSIS COPYRIGHT: BIOL ABS. The reduction of chromium from the Cr(VI) to the Cr(III) state by the presence of elemental, or zero-oxidation-state, iron metal was studied to evaluate the feasibility of such a process for subsurface chromate remediation. Reactions were studied in systems of natural aquifer materials with varying geochemistry. Different forms of iron metal had significantly different abilities to reduce chromate, ranging from extremely rapid to essentially no effect. Impure, partially oxidized iron was most effective, with iron quantity being the most important rate factor, followed by aquifer material type and solid:solution ratio. Evidence for chromium-iron hydroxide solid solution (Crx,Fe1-x)(OH)3(SS) formation was obtained by electron probe microanalysis. A cyclic, multiple reaction electrochemical corrosion mechanism, enhanced by the development of an electrical double-layer analogue, is proposed to explain the differing iron reactivities and aquifer material effects"
1516299,Poulton et al. 1989,The effect of hexavalent chromium on the critical thermal maximum and body burden of clioperla-clio plecoptera perlodidae,Biosis copyright: biol abs. rrm mature nymphs insect larvae contamination toxicity pollution exposure tolerance,The effect of hexavalent chromium on the critical thermal maximum and body burden of clioperla-clio plecoptera perlodidae Abs: Biosis copyright: biol abs. rrm mature nymphs insect larvae contamination toxicity pollution exposure tolerance
1516298,Posta et al. 1996,Cr(III) and Cr(VI) on-line preconcentration and determination with high performance flow flame emission spectrometry in natural samples,BIOSIS COPYRIGHT: BIOL ABS. Methods for the on-line chromatographic preconcentration of Cr(III) and Cr(VI) have been developed. Cr(VI) has been preconcentrated on an RP C18 silica based column with tetrabutylammonium-bromide (TBABr) as ion-pairing agent. Specially for Cr(III) a new and effective preconcentration technique based on the sorption of Cr(III)-ions in a C18 column in presence of KH-phthalate has been developed. The efficiency of sample introduction into the atomic emission spectrometer could be improved by hydraulic high pressure nebulization. For the detection of chromium the acetylene2O flame has been used as a powerful emission spectrometric source. Applying these steps the detection limit (3sigma) could be improved to 25 pg/mL for Cr(III) and to 20 pg/mL for Cr(VI). The method has been applied for the chromium speciation in natural water samples.,Cr(III) and Cr(VI) on-line preconcentration and determination with high performance flow flame emission spectrometry in natural samples Abs: BIOSIS COPYRIGHT: BIOL ABS. Methods for the on-line chromatographic preconcentration of Cr(III) and Cr(VI) have been developed. Cr(VI) has been preconcentrated on an RP C18 silica based column with tetrabutylammonium-bromide (TBABr) as ion-pairing agent. Specially for Cr(III) a new and effective preconcentration technique based on the sorption of Cr(III)-ions in a C18 column in presence of KH-phthalate has been developed. The efficiency of sample introduction into the atomic emission spectrometer could be improved by hydraulic high pressure nebulization. For the detection of chromium the acetylene2O flame has been used as a powerful emission spectrometric source. Applying these steps the detection limit (3sigma) could be improved to 25 pg/mL for Cr(III) and to 20 pg/mL for Cr(VI). The method has been applied for the chromium speciation in natural water samples.
1516297,Posta et al. 1993,High-performance flow flame atomic absorption spectrometry for automated on-line separation and determination of chromium(III)/chromium(VI) and preconcentration of chromium(VI),"BIOSIS COPYRIGHT: BIOL ABS. High-performance flow atomic spectrometry permits the fully automated separation of Cr(III)/ Cr(VI) species and subsequent flame AAS determination within only 1 min. An HPLC integrator at the output of the flame AA spectrometer renders possible the simultaneous signal processing of both oxidation states. Samples of drinking water, waste water, and extracts of soils were investigated. The relevant detection limits are 0.03 Cr(III) or 0.02 mug/mL Cr(VI) (3sigma values, N = 25). The relative standa deviation amounts to mug/ mL). With the same type of chromium speciation column (modified C18 type), Cr(VI) can be preconcentrated from drinking water and then determined online by flame AAS within 3.5 min. A detection limit of 0.5 mug (3sigma value) can be attained when a sample volume of 5 mL is used; the standard deviation is 3.1 (10 mug/L Cr(VI)) or 1.5% (100 mug/L Cr(VI)).","High-performance flow flame atomic absorption spectrometry for automated on-line separation and determination of chromium(III)/chromium(VI) and preconcentration of chromium(VI) Abs: BIOSIS COPYRIGHT: BIOL ABS. High-performance flow atomic spectrometry permits the fully automated separation of Cr(III)/ Cr(VI) species and subsequent flame AAS determination within only 1 min. An HPLC integrator at the output of the flame AA spectrometer renders possible the simultaneous signal processing of both oxidation states. Samples of drinking water, waste water, and extracts of soils were investigated. The relevant detection limits are 0.03 Cr(III) or 0.02 mug/mL Cr(VI) (3sigma values, N = 25). The relative standa deviation amounts to mug/ mL). With the same type of chromium speciation column (modified C18 type), Cr(VI) can be preconcentrated from drinking water and then determined online by flame AAS within 3.5 min. A detection limit of 0.5 mug (3sigma value) can be attained when a sample volume of 5 mL is used; the standard deviation is 3.1 (10 mug/L Cr(VI)) or 1.5% (100 mug/L Cr(VI))."
1516296,Posta et al. 1996,On-line separation and preconcentration of chromium species in seawater,"BIOSIS COPYRIGHT: BIOL ABS. A study was undertaken to ascertain the analytical capabilities of combined HPLC-ICP-AES with ultrasonic nebulization or HPLC-ICP-MS systems to perform on-line separation of CrIII-CrVI and on-line preconcentration of CrVI. Tetrabutylammonium bromide was used as the ion-pair forming agent and a reverse phase C18 column was used for separation. By optimizing the conditions of separation and preconcentration as well as plasma parameters a method could be developed for the determination of CrIII and CrVI in seawater by HPLC-ICP-AES with ultrasonic nebulization. In this matrix detection limits (3sigma criterion) turned out to be 4.6 ng/ml for CrIII and 3.7 ng/ml for CrVI, while the RSD is 2%-3% at the level of 100 ng/ml Cr. As the preconcentration of CrVI is regarded, the detection limit of ICP-AES depends, among others, on the sample volume loaded onto the column. It resulted to be 0.20 ng/ml for an initial volume of 2 ml, while the RSD at 10 ng/ml CrVI was | 3.8%. On the","On-line separation and preconcentration of chromium species in seawater Abs: BIOSIS COPYRIGHT: BIOL ABS. A study was undertaken to ascertain the analytical capabilities of combined HPLC-ICP-AES with ultrasonic nebulization or HPLC-ICP-MS systems to perform on-line separation of CrIII-CrVI and on-line preconcentration of CrVI. Tetrabutylammonium bromide was used as the ion-pair forming agent and a reverse phase C18 column was used for separation. By optimizing the conditions of separation and preconcentration as well as plasma parameters a method could be developed for the determination of CrIII and CrVI in seawater by HPLC-ICP-AES with ultrasonic nebulization. In this matrix detection limits (3sigma criterion) turned out to be 4.6 ng/ml for CrIII and 3.7 ng/ml for CrVI, while the RSD is 2%-3% at the level of 100 ng/ml Cr. As the preconcentration of CrVI is regarded, the detection limit of ICP-AES depends, among others, on the sample volume loaded onto the column. It resulted to be 0.20 ng/ml for an initial volume of 2 ml, while the RSD at 10 ng/ml CrVI was | 3.8%. On the"
1516295,Poschenrieder and  Gunse 1985,Leaf water potential in chromium-vi treated bean plants phaseolus-vulgaris au - barcelo j,Biosis copyright: biol abs. rrm abstract,Leaf water potential in chromium-vi treated bean plants phaseolus-vulgaris au - barcelo j Abs: Biosis copyright: biol abs. rrm abstract
1516293,Pomerantz and  Ross 1968,Captan and structurally related compounds: Thin-layer and gas-liquid chromatography,"HAPAB A thin-layer chromatographic method was developed which differentiates between captan, folpet, Difolatan, tetrahydrophthalimid e, phthalimide, captan epoxide, Difolatan epoxide and tetrahydrophthalimide epoxide. The method is based upon chromatography on silica gel with 1% methanol in chloroform as solvent for development, followed by sequential color development of the resulting spots. Resorcinol, N,N-dimethyl-p-phenylenediamine, potassium permanganate and chromic acid were the chromogenic sprays of choice. Tabulated data include the response of the above compounds to the chromogenic reagents, their lower limit of detection, as well as their Rf values in 1% methanol in chloroform. Gas-liquid chromotography was also employed to study the above compounds. Relative retention time and detector response data are tabulated. For this study a Barber- Coleman Model 5360 gas chromatograph was used either with a column of 10% DC-200 on 80-100 mech Gas Chrom Q or a mixed column of equal portions of 15% QF-1 and 10% DC-200, each on 100-120 mesh Gas Chrom Q. Half-scale deflection data were obtained with an electron capture detector under conditions which gave half-scale deflection ( on a 5 mv recorder ) for 1 ng heptachlor epoxide. ANALYSIS 68/11/00, 24 1968","Captan and structurally related compounds: Thin-layer and gas-liquid chromatography Abs: HAPAB A thin-layer chromatographic method was developed which differentiates between captan, folpet, Difolatan, tetrahydrophthalimid e, phthalimide, captan epoxide, Difolatan epoxide and tetrahydrophthalimide epoxide. The method is based upon chromatography on silica gel with 1% methanol in chloroform as solvent for development, followed by sequential color development of the resulting spots. Resorcinol, N,N-dimethyl-p-phenylenediamine, potassium permanganate and chromic acid were the chromogenic sprays of choice. Tabulated data include the response of the above compounds to the chromogenic reagents, their lower limit of detection, as well as their Rf values in 1% methanol in chloroform. Gas-liquid chromotography was also employed to study the above compounds. Relative retention time and detector response data are tabulated. For this study a Barber- Coleman Model 5360 gas chromatograph was used either with a column of 10% DC-200 on 80-100 mech Gas Chrom Q or a mixed column of equal portions of 15% QF-1 and 10% DC-200, each on 100-120 mesh Gas Chrom Q. Half-scale deflection data were obtained with an electron capture detector under conditions which gave half-scale deflection ( on a 5 mv recorder ) for 1 ng heptachlor epoxide. ANALYSIS 68/11/00, 24 1968"
1516290,Pollard et al. 1994,Bioremediation of petroleum-and creosote-contaminated soils a review of constraints,Biosis copyright: biol abs. rrm literature review polynuclear aromatic hydrocarbons bioavailability metals biotransformation,Bioremediation of petroleum-and creosote-contaminated soils a review of constraints Abs: Biosis copyright: biol abs. rrm literature review polynuclear aromatic hydrocarbons bioavailability metals biotransformation
1516289,Pobozy et al. 1996,Ion chromatographic speciation of chromium with diphenylcarbazide-based spectrophotometric detection,"BIOSIS COPYRIGHT: BIOL ABS. Two different ion chromatographic procedures were developed for the speciation of different oxidation states of chromium with use of anion-exchange column Hamilton PRP-X100, phthalate mobile phase and spectrophotometric detection based on post-column reaction of Cr(VI) with diphenylcarbazide. Due to element-specific detection such a determination can be carried out with retention of Cr(VI) and elution of Cr(III) in the void peak. In the second procedure developed, Cr(III) is complexed with DCTA, and the obtained complex is also retained on an anion-exchange column. For 200 mul sample volume the estimated limits of detection were for the first procedure 2.5 and 1.8 ng/ml for Cr(III) and Cr(IV), respectively, whereas for the second one 4.5 and 1.5 ng/ml for Cr(III) and Cr(VI), respectively. In the method with complexation for Cr(III) a better resolution of analytes was obtained and this m4thod was applied for chromium speciation in spiked river waters. The obtained result","Ion chromatographic speciation of chromium with diphenylcarbazide-based spectrophotometric detection Abs: BIOSIS COPYRIGHT: BIOL ABS. Two different ion chromatographic procedures were developed for the speciation of different oxidation states of chromium with use of anion-exchange column Hamilton PRP-X100, phthalate mobile phase and spectrophotometric detection based on post-column reaction of Cr(VI) with diphenylcarbazide. Due to element-specific detection such a determination can be carried out with retention of Cr(VI) and elution of Cr(III) in the void peak. In the second procedure developed, Cr(III) is complexed with DCTA, and the obtained complex is also retained on an anion-exchange column. For 200 mul sample volume the estimated limits of detection were for the first procedure 2.5 and 1.8 ng/ml for Cr(III) and Cr(IV), respectively, whereas for the second one 4.5 and 1.5 ng/ml for Cr(III) and Cr(VI), respectively. In the method with complexation for Cr(III) a better resolution of analytes was obtained and this m4thod was applied for chromium speciation in spiked river waters. The obtained result"
1516287,Phillips et al. 1999,Portland cement dust. Criteria document for an occupational exposure limit AU - Fairhurst S,"Portland cement, especially when wet, is irritant and/or corrosive to the skin and is a predicted eye irritant. Many cases have been reported of cement dermatitis appearing to arise as a result of skin sensitization to hexavalent chromium in cement. Imprecise studies have recorded that repeated inhalation produces respiratory effects. Mortality studies on cement workers have found no increased incidence of death from non-malignant respiratory disease; the position regarding the carcinogenicity remains unclear. Occupational exposure standards: 10mg/m|3| total inhalable dust (8h TWA); 5mg/m|3| respirable dust (8h TWA). List of abbreviations.","Portland cement dust. Criteria document for an occupational exposure limit AU - Fairhurst S Abs: Portland cement, especially when wet, is irritant and/or corrosive to the skin and is a predicted eye irritant. Many cases have been reported of cement dermatitis appearing to arise as a result of skin sensitization to hexavalent chromium in cement. Imprecise studies have recorded that repeated inhalation produces respiratory effects. Mortality studies on cement workers have found no increased incidence of death from non-malignant respiratory disease; the position regarding the carcinogenicity remains unclear. Occupational exposure standards: 10mg/m|3| total inhalable dust (8h TWA); 5mg/m|3| respirable dust (8h TWA). List of abbreviations."
1516286,Philipot et al. 1985,Hexavalent chromium removal from drinking water,Biosis copyright: biol abs. rrm iron sulfate ultrafiltration metal pollution air pollution industrial pollution,Hexavalent chromium removal from drinking water Abs: Biosis copyright: biol abs. rrm iron sulfate ultrafiltration metal pollution air pollution industrial pollution
1516285,Pfeiffer et al. 1980,"Fate of chromium in a tributary of the Iraja River, Rio de Janeiro, Brazil","HEEP COPYRIGHT: BIOL ABS. Total Cr concentrations were determined in water, bottom sediments and suspended particles, collected during 7 mo. at 5 stations along a tributary of the Iraja River (Brazil), where an electroplating industry discharged its untreated effluents. Confluence between the 2 rivers was 1 km above its outfall into the Guanabara Bay (Brazil). At 2 stations, a differential analytical method was employed to ascertain Cr3+ and Cr6+ concentrations in water samples. Industrial effluent samples were also analyzed showing that 537 kg of total Cr was released monthly, mainly in Cr6+ form. Adsorption experiments were carried out in the laboratory with water and suspended particles from the area studied, using 51Cr as chromate. Total Cr concentrations in water, bottom sediments and suspended particles ranged between 0.14-80 ppm, 1420-54,300 ppm and 2210-61,070 ppm, respectively. A fast removal of total Cr from water and a high uptake by suspended particles were observed. At 150 m from point of release, Cr present in water was mainly in Cr6+ form. After 300 m, Cr3+ was present in some samples as the major constituent. Some observations on fast removal of Cr from water were presented.","Fate of chromium in a tributary of the Iraja River, Rio de Janeiro, Brazil Abs: HEEP COPYRIGHT: BIOL ABS. Total Cr concentrations were determined in water, bottom sediments and suspended particles, collected during 7 mo. at 5 stations along a tributary of the Iraja River (Brazil), where an electroplating industry discharged its untreated effluents. Confluence between the 2 rivers was 1 km above its outfall into the Guanabara Bay (Brazil). At 2 stations, a differential analytical method was employed to ascertain Cr3+ and Cr6+ concentrations in water samples. Industrial effluent samples were also analyzed showing that 537 kg of total Cr was released monthly, mainly in Cr6+ form. Adsorption experiments were carried out in the laboratory with water and suspended particles from the area studied, using 51Cr as chromate. Total Cr concentrations in water, bottom sediments and suspended particles ranged between 0.14-80 ppm, 1420-54,300 ppm and 2210-61,070 ppm, respectively. A fast removal of total Cr from water and a high uptake by suspended particles were observed. At 150 m from point of release, Cr present in water was mainly in Cr6+ form. After 300 m, Cr3+ was present in some samples as the major constituent. Some observations on fast removal of Cr from water were presented."
1516281,Peternac and  Legovic 1986,Uptake distribution and loss of chromium in the crab xantho-hydrophilus,Biosis copyright: biol abs. rrm organ distribution trivalent chromium,Uptake distribution and loss of chromium in the crab xantho-hydrophilus Abs: Biosis copyright: biol abs. rrm organ distribution trivalent chromium
1516280,Periasamy et al. 1991,Studies on chromium(VI) removal by activated groundnut husk carbon,BIOSIS COPYRIGHT: BIOL ABS. The activated carbon prepared by carbonization of groundnut husk with sulfuric acid followed by thermal activation showed 80% removal of chromium (VI) at optimum pH 2.0 when a minimum chromium (VI) to carbon ratio of 0.00416 was maintained. The above ratio was valid even for higher concentrations of chromium (VI). The adsorption capacities calculated by Freundlich Adsorption Isotherm gave 5.61 mg/g and 3.54 mg/g of chromium (VI) removal at pH 2.0 for distilled and tap waters respectively. The overall rate constants obtained by kinetic experiments indicated that chromium (VI) removal was more as the concentration decreased.,Studies on chromium(VI) removal by activated groundnut husk carbon Abs: BIOSIS COPYRIGHT: BIOL ABS. The activated carbon prepared by carbonization of groundnut husk with sulfuric acid followed by thermal activation showed 80% removal of chromium (VI) at optimum pH 2.0 when a minimum chromium (VI) to carbon ratio of 0.00416 was maintained. The above ratio was valid even for higher concentrations of chromium (VI). The adsorption capacities calculated by Freundlich Adsorption Isotherm gave 5.61 mg/g and 3.54 mg/g of chromium (VI) removal at pH 2.0 for distilled and tap waters respectively. The overall rate constants obtained by kinetic experiments indicated that chromium (VI) removal was more as the concentration decreased.
1516279,Perez-Garcia et al. 1993,Rapid respirometric toxicity test sensitivity to metals,Biosis copyright: biol abs. rrm saccharomyces-cerevisiae pseudomonas-fluorescens fungus bacteria microorganism wastewater treatment toxicity water pollution effects heavy metals,Rapid respirometric toxicity test sensitivity to metals Abs: Biosis copyright: biol abs. rrm saccharomyces-cerevisiae pseudomonas-fluorescens fungus bacteria microorganism wastewater treatment toxicity water pollution effects heavy metals
1516278,Peraniemi and  Ahlgren 1995,Separation of microgram quantities of Cr(III) and Cr(VI) in aqueous solutions and determination by energy dispersive X-ray fluorescence spectrometry,"BIOSIS COPYRIGHT: BIOL ABS. A procedure was developed for the separation and independent determination of microgram quantities of Cr(VI) and Cr(III) in aqueous solution. Cr(VI) was adsorbed onto zirconium-loaded activated charcoal (ZrC*), and Cr(III) was collected by Fe(OH)3 precipitation and the precipitate bound to activated charcoal. Chromium in the activated charcoal was measured by energy dispersive X-ray fluorescence spectrometry. The detection limits for both chromium species were better than 0.05 mg/l. The procedure was tested with the Ground Water and Waste Water Pollution Control Check Standard WP-15 spiked with Cr(VI) and several samples from the plating industry.","Separation of microgram quantities of Cr(III) and Cr(VI) in aqueous solutions and determination by energy dispersive X-ray fluorescence spectrometry Abs: BIOSIS COPYRIGHT: BIOL ABS. A procedure was developed for the separation and independent determination of microgram quantities of Cr(VI) and Cr(III) in aqueous solution. Cr(VI) was adsorbed onto zirconium-loaded activated charcoal (ZrC*), and Cr(III) was collected by Fe(OH)3 precipitation and the precipitate bound to activated charcoal. Chromium in the activated charcoal was measured by energy dispersive X-ray fluorescence spectrometry. The detection limits for both chromium species were better than 0.05 mg/l. The procedure was tested with the Ground Water and Waste Water Pollution Control Check Standard WP-15 spiked with Cr(VI) and several samples from the plating industry."
1516277,Pencheva 1978,A plant of organic synthesis as a source of atmospheric contamination,"HEEP COPYRIGHT: BIOL ABS. Atmospheric contamination due to organic synthesis was examined in the town of Ruse (Bulgaria). During 1976-1977 dust, Pb aerosols, Cr6+, SO2, H2SO4, ammonium hydrocyanogen, aldehydes, formaldehyde, O3, NO2 and undefined carbohydrates were measured. Dust, Pb, H2SO4, HCl, ammonium, hydrocyanogen, aldehydes and NO2 exceeded the threshold values. The dynamics of contamination correlated with seasons, established mean and maximal concentrations of the contaminants and data from the plastic-producing chemical plant in Ruse. The production of organic synthesis was a serious contamination source in Ruse. Purification of gases by creating central air conditioning and fan systems was questioned.","A plant of organic synthesis as a source of atmospheric contamination Abs: HEEP COPYRIGHT: BIOL ABS. Atmospheric contamination due to organic synthesis was examined in the town of Ruse (Bulgaria). During 1976-1977 dust, Pb aerosols, Cr6+, SO2, H2SO4, ammonium hydrocyanogen, aldehydes, formaldehyde, O3, NO2 and undefined carbohydrates were measured. Dust, Pb, H2SO4, HCl, ammonium, hydrocyanogen, aldehydes and NO2 exceeded the threshold values. The dynamics of contamination correlated with seasons, established mean and maximal concentrations of the contaminants and data from the plastic-producing chemical plant in Ruse. The production of organic synthesis was a serious contamination source in Ruse. Purification of gases by creating central air conditioning and fan systems was questioned."
1516275,Pedersen et al. 1987,Some problems in sampling analysis and evaluation of welding fumes containing chromium-vi,Biosis copyright: biol abs. rrm workers fumigant metals metal industry stainless steel fume reduction occupational toxicology hazardous occupation hazardous materials industrial hygiene,Some problems in sampling analysis and evaluation of welding fumes containing chromium-vi Abs: Biosis copyright: biol abs. rrm workers fumigant metals metal industry stainless steel fume reduction occupational toxicology hazardous occupation hazardous materials industrial hygiene
1516274,Paustenbach et al. 1990,Potential impact on standards for toxic air contaminants,Biosis copyright: biol abs. rrm environmental surveillance risk assessment health hazard government regulation risk management,Potential impact on standards for toxic air contaminants Abs: Biosis copyright: biol abs. rrm environmental surveillance risk assessment health hazard government regulation risk management
1516271,Patterson et al. 1992,The effects of nine diet and water combinations on the culture health of Ceriodaphnia dubia,"BIOSIS COPYRIGHT: BIOL ABS. Culture health of Ceriodaphnia dubia were evaluated for organisms cultured with all combinations of three foods and three waters. The criteria used to assess health of cultures included adult and neonate weights, time required to produce first broods, neonate production, adult survival, and resistance to hexavalent chromium. Diet-water combinations that produced the most neonates were not found to produce adults that were more resistant to chromium than those that produced fewer neonates. Of those evaluated, a diet of Selenastrum capricornutum and a yeast-trout food-cereal leaf mixture was best for culturing and testing Ceriodaphnia. The best tested synthetic culture water was a mixture of nine parts reconstituted hard water and one part bottled mineral water.","The effects of nine diet and water combinations on the culture health of Ceriodaphnia dubia Abs: BIOSIS COPYRIGHT: BIOL ABS. Culture health of Ceriodaphnia dubia were evaluated for organisms cultured with all combinations of three foods and three waters. The criteria used to assess health of cultures included adult and neonate weights, time required to produce first broods, neonate production, adult survival, and resistance to hexavalent chromium. Diet-water combinations that produced the most neonates were not found to produce adults that were more resistant to chromium than those that produced fewer neonates. Of those evaluated, a diet of Selenastrum capricornutum and a yeast-trout food-cereal leaf mixture was best for culturing and testing Ceriodaphnia. The best tested synthetic culture water was a mixture of nine parts reconstituted hard water and one part bottled mineral water."
1516268,Pastides et al. 1994,Transforming industrial hygiene data for use in epidemiologic studies: A case study of hexavalent chromium,"BIOSIS COPYRIGHT: BIOL ABS. This paper presents the methods that were developed for estimating past occupational exposure to hexavalent chromium (Cr+6) as part of an epidemiologic study. Data were available from a variety of industrial records but were flawed and had to be carefully evaluated, and often transformed, before they could be used for exposure reconstruction. The study goal was to assess the health risks associated with chromate production in a cohort of 398 workers with at least one year of employment. Substantial personal and area air samples of Cr+6 were available from industrial hygiene records, but the sampling procedures were not uniform. Additionally, important decisions had to be made concerning gaps in available data for certain time periods, exposure levels recorded as ""less than the limit of detection,"" monitoring results requiring recalculation, and various observed discrepancies in reporting conventions. Usual exposure in 22 distinct plant exposure areas was characterized b","Transforming industrial hygiene data for use in epidemiologic studies: A case study of hexavalent chromium Abs: BIOSIS COPYRIGHT: BIOL ABS. This paper presents the methods that were developed for estimating past occupational exposure to hexavalent chromium (Cr+6) as part of an epidemiologic study. Data were available from a variety of industrial records but were flawed and had to be carefully evaluated, and often transformed, before they could be used for exposure reconstruction. The study goal was to assess the health risks associated with chromate production in a cohort of 398 workers with at least one year of employment. Substantial personal and area air samples of Cr+6 were available from industrial hygiene records, but the sampling procedures were not uniform. Additionally, important decisions had to be made concerning gaps in available data for certain time periods, exposure levels recorded as ""less than the limit of detection,"" monitoring results requiring recalculation, and various observed discrepancies in reporting conventions. Usual exposure in 22 distinct plant exposure areas was characterized b"
1516266,Parupudi et al. 1997,Effects of soil composition on the removal of chromium by electrokinetics. AU - REDDY KR,"BIOSIS COPYRIGHT: BIOL ABS. Electrokinetic experiments were conducted on three different types of soil: glacial till, kaolin and Na-montmorillonite, in order to investigate the effect of soil mineralogy and naturally occurring hematite (Fe2O3) on the removal of chromium from these soils. Batch tests were also performed to characterize Cr(VI) adsorption onto these soils. This study has shown that soils which contain high carbonate buffers, such as the glacial till, hinder the development of an acid front, which results in alkaline conditions throughout the soil during electrokinetic remediation. However, soils possessing low buffering capacity, such as kaolin and Na-montmorillonite, favor the development of an acid front which results in a distinct pH gradient with pH values varying from 2 near the anode to over 11 near the cathode. The results from the adsorption tests showed that Cr(VI) adsorption onto soils depends on the soil type and soil pH. The adsorption of Cr(VI) was found to be governed b","Effects of soil composition on the removal of chromium by electrokinetics. AU - REDDY KR Abs: BIOSIS COPYRIGHT: BIOL ABS. Electrokinetic experiments were conducted on three different types of soil: glacial till, kaolin and Na-montmorillonite, in order to investigate the effect of soil mineralogy and naturally occurring hematite (Fe2O3) on the removal of chromium from these soils. Batch tests were also performed to characterize Cr(VI) adsorption onto these soils. This study has shown that soils which contain high carbonate buffers, such as the glacial till, hinder the development of an acid front, which results in alkaline conditions throughout the soil during electrokinetic remediation. However, soils possessing low buffering capacity, such as kaolin and Na-montmorillonite, favor the development of an acid front which results in a distinct pH gradient with pH values varying from 2 near the anode to over 11 near the cathode. The results from the adsorption tests showed that Cr(VI) adsorption onto soils depends on the soil type and soil pH. The adsorption of Cr(VI) was found to be governed b"
1516264,Parr and  Taylor 1982,Germination and growth effects of hexavalent chromium in Orocol TL (a Corrosion inhibitor) on Phaseolus vulgaris (cultivar Bush Blue Lake),"HEEP COPYRIGHT: BIOL ABS. Research was conducted on the potential for germination and growth effects in bush beans (P. vulgaris L. cv. Bush Blue Lake) from hexavalent chromium in Orocol TL, a proprietary chromated, zinc-phosphate compound added to DOE (Department of Energy) cooling water systems (in the USA) for corrosion inhibition. Studies were conducted at low and high Orocol TL concentrations in the soil by adjusting soil pH and the percent of organic matter. Germination effects were determined for seeds germinated in soils adjusted to differing pH ranges (4-4.5, 5-5.5 and 6.5-7), levels of organic matter (1.8%, 3% and 5%), and Orocol TL amendments (control of 0, 10 and 500 mug/g Cr). Growth responses (effects) were determined from plants cultured in the same soil treatment combinations as described for the germination study. High levels (500 mug/g) of hexavalent Cr in soil (as Orocol TL) affected germination and growth, while a high level of organic matter significantly reduced Cr toxicity on germination. At lower Cr concentrations there was significant uptake by all plant parts, with a corresponding reduction in biomass of leaves. Consequently, adjustments of soil pH from 4.0 to 7.0 apparently had no significant effect on Cr uptake in plants. Increasing the organic matter level to 5%, while decreasing the toxicity of high Cr levels to germinating seed, did not affect Cr uptake.","Germination and growth effects of hexavalent chromium in Orocol TL (a Corrosion inhibitor) on Phaseolus vulgaris (cultivar Bush Blue Lake) Abs: HEEP COPYRIGHT: BIOL ABS. Research was conducted on the potential for germination and growth effects in bush beans (P. vulgaris L. cv. Bush Blue Lake) from hexavalent chromium in Orocol TL, a proprietary chromated, zinc-phosphate compound added to DOE (Department of Energy) cooling water systems (in the USA) for corrosion inhibition. Studies were conducted at low and high Orocol TL concentrations in the soil by adjusting soil pH and the percent of organic matter. Germination effects were determined for seeds germinated in soils adjusted to differing pH ranges (4-4.5, 5-5.5 and 6.5-7), levels of organic matter (1.8%, 3% and 5%), and Orocol TL amendments (control of 0, 10 and 500 mug/g Cr). Growth responses (effects) were determined from plants cultured in the same soil treatment combinations as described for the germination study. High levels (500 mug/g) of hexavalent Cr in soil (as Orocol TL) affected germination and growth, while a high level of organic matter significantly reduced Cr toxicity on germination. At lower Cr concentrations there was significant uptake by all plant parts, with a corresponding reduction in biomass of leaves. Consequently, adjustments of soil pH from 4.0 to 7.0 apparently had no significant effect on Cr uptake in plants. Increasing the organic matter level to 5%, while decreasing the toxicity of high Cr levels to germinating seed, did not affect Cr uptake."
1516263,Parlak et al. 1999,Accumulation and loss of chromium by mussels (M. galloprovincialis),Biosis copyright: biol abs. rrm research article mytilus galloprovincialis bioindicator pollution toxicology environmental contamination marine ecology chromiumiii loss pollutant heavy metal bioaccumulation chromiumvi,Accumulation and loss of chromium by mussels (M. galloprovincialis) Abs: Biosis copyright: biol abs. rrm research article mytilus galloprovincialis bioindicator pollution toxicology environmental contamination marine ecology chromiumiii loss pollutant heavy metal bioaccumulation chromiumvi
1516262,Parkash et al. 1991,Malachite green as a reagent for detection and spectrophotometric determination of chromium(VI),"BIOSIS COPYRIGHT: BIOL ABS. A sensitive and inexpensive method of spectrophotometric determination of chromium(VI), based on the absorbance of its complex with malachite green and acetic acid at pH 2.5 is reported. The complex shows a molar absorptivity of 8nd acetic acid as reference solution. The effect of time, temperature, pH and reagent concentration is studied and optimum operating conditions are established. Beer's law is applicable in the concentration range 2.0-22.8 mug/ml chromium(VI). The resin beads act as a catalyst and as little as 1.6 mug of chromium(VI) is detected in the resin phase as compared to 4.1 mug in the solution phase. The standard deviation in the determinations is |0.40 mug/ml for a 10.35 mug/ml solution.","Malachite green as a reagent for detection and spectrophotometric determination of chromium(VI) Abs: BIOSIS COPYRIGHT: BIOL ABS. A sensitive and inexpensive method of spectrophotometric determination of chromium(VI), based on the absorbance of its complex with malachite green and acetic acid at pH 2.5 is reported. The complex shows a molar absorptivity of 8nd acetic acid as reference solution. The effect of time, temperature, pH and reagent concentration is studied and optimum operating conditions are established. Beer's law is applicable in the concentration range 2.0-22.8 mug/ml chromium(VI). The resin beads act as a catalyst and as little as 1.6 mug of chromium(VI) is detected in the resin phase as compared to 4.1 mug in the solution phase. The standard deviation in the determinations is |0.40 mug/ml for a 10.35 mug/ml solution."
1516261,Parikh et al. 1997,Hexavalent and trivalent chromium affect specific phases but not rate of the electric organ discharge in a mormyrid,Biosis copyright: biol abs. rrm meeting abstract meeting poster gnathonemus-petersii electric fish mormyrid nervous system electric organ discharge hexavalent chromium heavy metals trivalent chromium discharge phases water quality electrocommunication,Hexavalent and trivalent chromium affect specific phases but not rate of the electric organ discharge in a mormyrid Abs: Biosis copyright: biol abs. rrm meeting abstract meeting poster gnathonemus-petersii electric fish mormyrid nervous system electric organ discharge hexavalent chromium heavy metals trivalent chromium discharge phases water quality electrocommunication
1516260,Paran'Ko et al. 1989,Experimental Assessment of the Combined Effect of Noise and Aerosols Existing in Steelworks,"The effects of exposure to a combined effect of noise at 85 and 95 decibels-A (dBA) and aerosols containing oxides of manganese (7439965), chromium (7440473), nickel (7440020) and silicon-dioxide (7631869) were studied in white-rats. Rats were exposed to constant white noise at 95dBA intensity and aerosols of manganese-oxide (1313139) at 7 or 21mg/m3, 85 or 95dBA noise and chromium-oxide (1308389) at 0.03mg/m3, or 85 or 95dBA noise and natural aerosols from an electric steel works containing manganese and nickel-oxide (10102439). The animals were exposed for 5 hours a day, five times a week for 4 months. Transient shifts were noted in the cardiovascular system and individual signs of depression of the function of the hypophysis and adrenal glands for combined exposures to aerosols and noise at the 85dbA level. At the higher noise level and aerosol exposure changes also occurred in the nervous system. Pronounced changes were observed of a superadditive nature. The combined action effects occurred mainly toward the end of the chronic experiment and were retained and sometimes got worse during the recovery period. The authors conclude that the basis of the harmful combined action of noise and the aerosols used here at small low intensities was the stress on the adaptive activity of the unified complex of regulatory systems, resulting in exhaustion and discoordination of the functions of these systems.","Experimental Assessment of the Combined Effect of Noise and Aerosols Existing in Steelworks Abs: The effects of exposure to a combined effect of noise at 85 and 95 decibels-A (dBA) and aerosols containing oxides of manganese (7439965), chromium (7440473), nickel (7440020) and silicon-dioxide (7631869) were studied in white-rats. Rats were exposed to constant white noise at 95dBA intensity and aerosols of manganese-oxide (1313139) at 7 or 21mg/m3, 85 or 95dBA noise and chromium-oxide (1308389) at 0.03mg/m3, or 85 or 95dBA noise and natural aerosols from an electric steel works containing manganese and nickel-oxide (10102439). The animals were exposed for 5 hours a day, five times a week for 4 months. Transient shifts were noted in the cardiovascular system and individual signs of depression of the function of the hypophysis and adrenal glands for combined exposures to aerosols and noise at the 85dbA level. At the higher noise level and aerosol exposure changes also occurred in the nervous system. Pronounced changes were observed of a superadditive nature. The combined action effects occurred mainly toward the end of the chronic experiment and were retained and sometimes got worse during the recovery period. The authors conclude that the basis of the harmful combined action of noise and the aerosols used here at small low intensities was the stress on the adaptive activity of the unified complex of regulatory systems, resulting in exhaustion and discoordination of the functions of these systems."
1516258,Pannain and  Santelli 1995,On the spectrophotometric flow injection determination of chromium(VI) in natural waters after on-line preconcentration on activated alumina,"BIOSIS COPYRIGHT: BIOL ABS. The feasibility of chromium(VI) preconcentration on to activated alumina in a continuous flow system with spectrophotometric detection was investigated. Chemical and flow variables, and the influence of concomitant species were studied both with and without preconcentration systems. The best results were obtained by using a 2.5 cm long, 1.6 mm i.d. alumina minicolumn, and selecting 1the preconcentrating medium and 0.1 M ammonium hydroxide as the eluent. The eluted chromium(VI) was mixed with diphenylcarbazide in acidic medium and the absorbance of the colored complex was measured at 540 nm. Linear calibrations for 5, 25 and 50 ml sample volumes were established over the concentration ranges 10-50 mug l-1, 2-10 mug l-1 and 1-5 mug l-1 with sensitivity enhancements of 44, 196 and 392 and detection limits (3sigma) of 3.0 mug l-1, 0.3 mug l-1 and 0.2 mug l-1, respectively. The method is relatively fast and cheap. Natural waters were analyzed with use of the developed proce","On the spectrophotometric flow injection determination of chromium(VI) in natural waters after on-line preconcentration on activated alumina Abs: BIOSIS COPYRIGHT: BIOL ABS. The feasibility of chromium(VI) preconcentration on to activated alumina in a continuous flow system with spectrophotometric detection was investigated. Chemical and flow variables, and the influence of concomitant species were studied both with and without preconcentration systems. The best results were obtained by using a 2.5 cm long, 1.6 mm i.d. alumina minicolumn, and selecting 1the preconcentrating medium and 0.1 M ammonium hydroxide as the eluent. The eluted chromium(VI) was mixed with diphenylcarbazide in acidic medium and the absorbance of the colored complex was measured at 540 nm. Linear calibrations for 5, 25 and 50 ml sample volumes were established over the concentration ranges 10-50 mug l-1, 2-10 mug l-1 and 1-5 mug l-1 with sensitivity enhancements of 44, 196 and 392 and detection limits (3sigma) of 3.0 mug l-1, 0.3 mug l-1 and 0.2 mug l-1, respectively. The method is relatively fast and cheap. Natural waters were analyzed with use of the developed proce"
1516257,Pankow et al. 1977,Analysis for chromium traces in the aquatic ecogystem: II. A study of Cr(III) and Cr(VI) in the Susquehanna River Basin of New York and Pennsylvania,"HEEP COPYRIGHT: BIOL ABS. A new procedure for the differential analysis of ppb concentrations of Cr(III) and Cr(VI) in natural waters was developed. Application of this technique to the analysis of natural water samples revealed the predominance of trivalent Cr in uncontaminated waters of the Upper Susquehanna River Basin (USA) (1-2 ppb). River water samples taken downstream of Binghamton, New York area sewage outfalls revealed an increase in the mean Cr(VI) content of the river from 1.6 ppb. The persistence of the Cr(VI) at least as far as 60 km downstream of the outfall area indicates that at these levels, little dissolved Cr(VI) is removed from the river as it flows away from a point of contamination. Concentrations of Cr in samples of river sediments also revealed Cr contamination below the outfall area, and Cr contamination extended at least as far as 60 km downstream of the outfall area.","Analysis for chromium traces in the aquatic ecogystem: II. A study of Cr(III) and Cr(VI) in the Susquehanna River Basin of New York and Pennsylvania Abs: HEEP COPYRIGHT: BIOL ABS. A new procedure for the differential analysis of ppb concentrations of Cr(III) and Cr(VI) in natural waters was developed. Application of this technique to the analysis of natural water samples revealed the predominance of trivalent Cr in uncontaminated waters of the Upper Susquehanna River Basin (USA) (1-2 ppb). River water samples taken downstream of Binghamton, New York area sewage outfalls revealed an increase in the mean Cr(VI) content of the river from 1.6 ppb. The persistence of the Cr(VI) at least as far as 60 km downstream of the outfall area indicates that at these levels, little dissolved Cr(VI) is removed from the river as it flows away from a point of contamination. Concentrations of Cr in samples of river sediments also revealed Cr contamination below the outfall area, and Cr contamination extended at least as far as 60 km downstream of the outfall area."
1516255,Pal et al. 1989,2-alpha pyridylthioquinaldinamide ptqa a novel fluorometric reagent in inorganic trace analysis i. the nonextractive nonquenching fluorescent method for the determination of chromium-vi,Biosis copyright: biol abs. rrm environmental sample chromium-iii chromium-iv chromium toxicity,2-alpha pyridylthioquinaldinamide ptqa a novel fluorometric reagent in inorganic trace analysis i. the nonextractive nonquenching fluorescent method for the determination of chromium-vi Abs: Biosis copyright: biol abs. rrm environmental sample chromium-iii chromium-iv chromium toxicity
1516252,Ouki and  Neufeld 1997,Use of activated carbon for the recovery of chromium from industrial wastewaters,"BIOSIS COPYRIGHT: BIOL ABS. A technique for the removal and recycling of hexavalent chromium from electroplating industries was developed. It involves a two-phase process which consists of (1) the use of an activated carbon bed for the accumulation of chromium onto the surface of activated carbon followed by (2) the regeneration of the carbon leading to a concentrated chromium solution with potential for reclamation or reuse within the plating operation. Results from continuous flow experiments showed that in excess of 99% chromium removal efficiency can be achieved. It was also revealed that regeneration of the exhausted carbon under acidic conditions recovered chromium in the trivalent state with concentrations as high as 3 g dm-3, more than 12 times the influent concentration. The adsorption capacity of the activated carbon was found to increase with successive cycles of adsorption/regeneration. However, when regeneration was achieved under alkaline conditions, the chromium was recovered in the","Use of activated carbon for the recovery of chromium from industrial wastewaters Abs: BIOSIS COPYRIGHT: BIOL ABS. A technique for the removal and recycling of hexavalent chromium from electroplating industries was developed. It involves a two-phase process which consists of (1) the use of an activated carbon bed for the accumulation of chromium onto the surface of activated carbon followed by (2) the regeneration of the carbon leading to a concentrated chromium solution with potential for reclamation or reuse within the plating operation. Results from continuous flow experiments showed that in excess of 99% chromium removal efficiency can be achieved. It was also revealed that regeneration of the exhausted carbon under acidic conditions recovered chromium in the trivalent state with concentrations as high as 3 g dm-3, more than 12 times the influent concentration. The adsorption capacity of the activated carbon was found to increase with successive cycles of adsorption/regeneration. However, when regeneration was achieved under alkaline conditions, the chromium was recovered in the"
1516251,Otabbong 1989,Chemistry of chromium in some swedish soils 2. fate and impact of added chromium on ph and status of soluble manganese in four soils,Biosis copyright: biol abs. rrm humus content retention recovery oxidation reduction pollutant,Chemistry of chromium in some swedish soils 2. fate and impact of added chromium on ph and status of soluble manganese in four soils Abs: Biosis copyright: biol abs. rrm humus content retention recovery oxidation reduction pollutant
1516249,Orhan and  Buyukgungor 1993,The removal of heavy metals by using agricultural wastes,Biosis copyright: biol abs. rrm research article agriculture waste management waste tea turkish coffee exhausted coffee nut shells absorption mh - minerals,The removal of heavy metals by using agricultural wastes Abs: Biosis copyright: biol abs. rrm research article agriculture waste management waste tea turkish coffee exhausted coffee nut shells absorption mh - minerals
1516247,Olah and  Pivoluska 1985,Determination of chromium-vi in welding fumes by radionuclide x-ray fluorescent analysis,Biosis copyright: biol abs. rrm worker industrial toxicology heavy metal indoor air pollution,Determination of chromium-vi in welding fumes by radionuclide x-ray fluorescent analysis Abs: Biosis copyright: biol abs. rrm worker industrial toxicology heavy metal indoor air pollution
1516245,Okada et al. 1983,Enhancement of RNA synthesis by chromium (III) in mouse liver,"HEEP COPYRIGHT: BIOL ABS. The effect of Cr(III) administration on hepatic RNA synthesis in mice was studied. Cr accumulated in mouse liver and 48 after i.p. injection of CrCl3 (0.005-5 mg Cr/kg body wt) ê 10% of the dose/g tissue remained. The accumulated Cr was still retained 64 days after administration (5 mg Cr/kg) with only a slight decrease. Approximately 20% of the hepatic Cr was detected in the nuclei. By administering CrCl3, RNA synthesis in mouse liver was markedly enhanced without altering the pool size of nucleotides. This enhancement was dose-dependent and statistically significant at 0.05 (P < 0.05), 0.5 (P < 0.01) and 5 mg Cr/kg (P < 0.01), and remained so for at least 16 days after administration of 5 mg Cr/kg. The syntheses of DNA and protein in mouse liver were not significantly changed by CrCl3 administration. Cr(VI) administration inhibited RNA synthesis in mouse liver. Cr(III) specifically enhanced RNA synthesis in mouse liver.","Enhancement of RNA synthesis by chromium (III) in mouse liver Abs: HEEP COPYRIGHT: BIOL ABS. The effect of Cr(III) administration on hepatic RNA synthesis in mice was studied. Cr accumulated in mouse liver and 48 after i.p. injection of CrCl3 (0.005-5 mg Cr/kg body wt) ê 10% of the dose/g tissue remained. The accumulated Cr was still retained 64 days after administration (5 mg Cr/kg) with only a slight decrease. Approximately 20% of the hepatic Cr was detected in the nuclei. By administering CrCl3, RNA synthesis in mouse liver was markedly enhanced without altering the pool size of nucleotides. This enhancement was dose-dependent and statistically significant at 0.05 (P < 0.05), 0.5 (P < 0.01) and 5 mg Cr/kg (P < 0.01), and remained so for at least 16 days after administration of 5 mg Cr/kg. The syntheses of DNA and protein in mouse liver were not significantly changed by CrCl3 administration. Cr(VI) administration inhibited RNA synthesis in mouse liver. Cr(III) specifically enhanced RNA synthesis in mouse liver."
1516244,Ohura et al. 1996,Potentiometric flow-injection determination of trace hydrogen peroxide based on its induced reaction in iron(III)-iron(II) potential buffer containing bromide and molybdenum(VI),"BIOSIS COPYRIGHT: BIOL ABS. A rapid and highly sensitive potentiometric flow-injection method for the determination of trace hydrogen peroxide was developed by use of an Fe(III)-Fe(II) potential buffer solution containing bromide and Mo(VI). The analytical method was based on a linear relationship between a concentration of hydrogen peroxide and a largely transient potential change of an oxidation-reduction potential electrode due to bromine generated by the reaction of hydrogen peroxide with the potential buffer solution. The oxidation of bromide to bromine by hydrogen peroxide occurred very rapidly with the assistance of Mo(VI) when Fe(II) existed in the potential buffer solution. It was estimated by batchwise experiments that hydroxyl radical, OH , was generated by the reaction of hydrogen peroxide with Fe(II) as an intermediate, and subsequently oxidized bromide to bromine. In a flow system, analytical sensitivities to hydrogen peroxide obtained by the detection of the transient change of pote","Potentiometric flow-injection determination of trace hydrogen peroxide based on its induced reaction in iron(III)-iron(II) potential buffer containing bromide and molybdenum(VI) Abs: BIOSIS COPYRIGHT: BIOL ABS. A rapid and highly sensitive potentiometric flow-injection method for the determination of trace hydrogen peroxide was developed by use of an Fe(III)-Fe(II) potential buffer solution containing bromide and Mo(VI). The analytical method was based on a linear relationship between a concentration of hydrogen peroxide and a largely transient potential change of an oxidation-reduction potential electrode due to bromine generated by the reaction of hydrogen peroxide with the potential buffer solution. The oxidation of bromide to bromine by hydrogen peroxide occurred very rapidly with the assistance of Mo(VI) when Fe(II) existed in the potential buffer solution. It was estimated by batchwise experiments that hydroxyl radical, OH , was generated by the reaction of hydrogen peroxide with Fe(II) as an intermediate, and subsequently oxidized bromide to bromine. In a flow system, analytical sensitivities to hydrogen peroxide obtained by the detection of the transient change of pote"
1516243,Ohtake 1992,New biological method for detoxification and removal of hexavalent chromium,Biosis copyright: biol abs. rrm bacteria microorganism wastewater treatment toxicity water pollution control biodegradation hazardous materials heavy metals,New biological method for detoxification and removal of hexavalent chromium Abs: Biosis copyright: biol abs. rrm bacteria microorganism wastewater treatment toxicity water pollution control biodegradation hazardous materials heavy metals
1516242,Ohtake et al. 1990,A survey of effective electron donors for reduction of toxic hexavalent chromium by enterobacter-cloacae strain ho1,Biosis copyright: biol abs. rrm detoxification technology wastewaters,A survey of effective electron donors for reduction of toxic hexavalent chromium by enterobacter-cloacae strain ho1 Abs: Biosis copyright: biol abs. rrm detoxification technology wastewaters
1516241,Ohta et al. 1987,Determination of Accumulated Heavy Metals and Other Substances in Human Lungs with Special Regard to the Toxic Effects of Hexavalent Chromium in a Factory Worker,"The accumulation of chromium (7440473) and other substances associated with inhaled hexavalent chromium were studied in a 54 year old male who was a chromate worker for 7 years and left the work circa 1965. Pathologic findings in the liver showed scattered foci of greyish yellow nodules, approximately 5 millimeters in diameter. Histologic examination revealed eosinophilic granulomas. Needle like crystalline chromium was found in the granulomas. Determinations of elements were made in the liver, lung, kidney, and hair. Chromium was 20 to 390 times higher, manganese (7439965) 2.3 to 17 times higher, and cobalt (7440484) 2.7 to 38 times higher in samples from the worker than in comparison samples. The data obtained in this study were valuable because of their implications for human exposures. The findings suggest that it may be hard to derive a risk factor for exposure to hexavalent chromium only by measuring accumulation of chromium. The finding of crystalline chromium in liver may be consistent with reports that hexavalent chromium passes easily through cell membranes.","Determination of Accumulated Heavy Metals and Other Substances in Human Lungs with Special Regard to the Toxic Effects of Hexavalent Chromium in a Factory Worker Abs: The accumulation of chromium (7440473) and other substances associated with inhaled hexavalent chromium were studied in a 54 year old male who was a chromate worker for 7 years and left the work circa 1965. Pathologic findings in the liver showed scattered foci of greyish yellow nodules, approximately 5 millimeters in diameter. Histologic examination revealed eosinophilic granulomas. Needle like crystalline chromium was found in the granulomas. Determinations of elements were made in the liver, lung, kidney, and hair. Chromium was 20 to 390 times higher, manganese (7439965) 2.3 to 17 times higher, and cobalt (7440484) 2.7 to 38 times higher in samples from the worker than in comparison samples. The data obtained in this study were valuable because of their implications for human exposures. The findings suggest that it may be hard to derive a risk factor for exposure to hexavalent chromium only by measuring accumulation of chromium. The finding of crystalline chromium in liver may be consistent with reports that hexavalent chromium passes easily through cell membranes."
1516238,Ogawa et al. 1976,Experimental study on absorption distribution and excretion of trivalent and hexavalent chromium compounds,Heep copyright: biol abs. abstract mouse toxicity metabolism,Experimental study on absorption distribution and excretion of trivalent and hexavalent chromium compounds Abs: Heep copyright: biol abs. abstract mouse toxicity metabolism
1516235,Nusko and  Heumann 1997,Cr(III)r(VI) speciation in aerosol particles by extractive separation and thermal ionization isotope dilution mass spectrometry,"BIOSIS COPYRIGHT: BIOL ABS. An isotope dilution mass spectrometric (IDMS) method, using the formation of positive thermal ions, was developed for Cr(III) and Cr(VI) speciation in aerosol particles. Cr(III) and Cr(VI) spike species, enriched in 53Cr, were applied for the isotope dilution step. After leaching of filter collected aerosol samples by an alkaline solution at pH 13, species separation was carried out by extraction with a liquid anion exchanger in methyl isobutyl ketone. Cr(VI) in the organic phase was re-extracted into an ammoniacal solution and chromium was then isolated from both fractions of species by electrodeposition. Detection limits of 30 pg/m3 for Cr(III) and of 8 pg/m3 for Cr(VI) were achieved in atmospheric aerosols for volumes of air samples of about 120 m3. These low detection limits allowed the determination of chromium species in continental aerosol particles in dependence on different seasons. The Cr(III) r(VI) ratio was always found to be about 0.3 whereas dust from soi","Cr(III)r(VI) speciation in aerosol particles by extractive separation and thermal ionization isotope dilution mass spectrometry Abs: BIOSIS COPYRIGHT: BIOL ABS. An isotope dilution mass spectrometric (IDMS) method, using the formation of positive thermal ions, was developed for Cr(III) and Cr(VI) speciation in aerosol particles. Cr(III) and Cr(VI) spike species, enriched in 53Cr, were applied for the isotope dilution step. After leaching of filter collected aerosol samples by an alkaline solution at pH 13, species separation was carried out by extraction with a liquid anion exchanger in methyl isobutyl ketone. Cr(VI) in the organic phase was re-extracted into an ammoniacal solution and chromium was then isolated from both fractions of species by electrodeposition. Detection limits of 30 pg/m3 for Cr(III) and of 8 pg/m3 for Cr(VI) were achieved in atmospheric aerosols for volumes of air samples of about 120 m3. These low detection limits allowed the determination of chromium species in continental aerosol particles in dependence on different seasons. The Cr(III) r(VI) ratio was always found to be about 0.3 whereas dust from soi"
1516234,Nusko and  Heumann 1994,Chromium speciation with isotope dilution mass spectrometry,Biosis copyright: biol abs. rrm research article chromiumiii chromiumvi waste water fresh water stability analytical method,Chromium speciation with isotope dilution mass spectrometry Abs: Biosis copyright: biol abs. rrm research article chromiumiii chromiumvi waste water fresh water stability analytical method
1516233,Nurhidayat and  Marchin 1997,Chromium vi reduction by an environmental isolate of bacillus thuringiensis,Biosis copyright: biol abs. rrm meeting abstract meeting poster bacillus-thuringiensis environmental isolate chromiumvi reduction pollutant heavy metals heavy metal polluted mining area bioprocess engineering pollution,Chromium vi reduction by an environmental isolate of bacillus thuringiensis Abs: Biosis copyright: biol abs. rrm meeting abstract meeting poster bacillus-thuringiensis environmental isolate chromiumvi reduction pollutant heavy metals heavy metal polluted mining area bioprocess engineering pollution
1516231,Norseth 1984,Biological Monitoring Of Metals And Metalloids. Chromium And Nickel,"The biological monitoring of chromium (7440473) and nickel (7440020) is reviewed. From the analytical point of view, urine is the preferable indicator for both nickel and chromium exposures, and flameless atomic absorption spectroscopy is the method of choice. The toxicokinetics of chromium are discussed. Hexavalent-chromium (18540299) (CrVI) is rapidly taken up by organs, including the erythrocytes, while trivalent-chromium (16065831) (CrIII) is bound in plasma. CrVI is rapidly reduced to CrIII in-vivo. There is only limited data for estimating risk based on biological monitoring of chromium. The risk of developing respiratory cancer depends on both the oxidation state of chromium and the solubility of chromium compounds having the same oxidation state. Available data indicates that slightly soluble chromates are the most potent carcinogens. Chromium exposures cannot be predicted from urinary excretion in one group of workers or for a single worker based on the exposure to excretion relationship in other groups. The toxicokinetics of nickel are summarized. A significant correlation between nickel in plasma and urinary nickel concentrations in exposed workers has been noted. High nickel concentrations have also been found in sweat, human parotid saliva and scalp hair, but these are not considered useful for biological monitoring. Plasma, urine or scalp hair nickel concentrations cannot be used to assess sensitivity as they do not differ between hypersensitive and non hypersensitive individuals. The author concludes that nickel exposure for a single worker cannot be estimated by biological monitoring; however, biological monitoring is useful in evaluating changes of exposure over time.","Biological Monitoring Of Metals And Metalloids. Chromium And Nickel Abs: The biological monitoring of chromium (7440473) and nickel (7440020) is reviewed. From the analytical point of view, urine is the preferable indicator for both nickel and chromium exposures, and flameless atomic absorption spectroscopy is the method of choice. The toxicokinetics of chromium are discussed. Hexavalent-chromium (18540299) (CrVI) is rapidly taken up by organs, including the erythrocytes, while trivalent-chromium (16065831) (CrIII) is bound in plasma. CrVI is rapidly reduced to CrIII in-vivo. There is only limited data for estimating risk based on biological monitoring of chromium. The risk of developing respiratory cancer depends on both the oxidation state of chromium and the solubility of chromium compounds having the same oxidation state. Available data indicates that slightly soluble chromates are the most potent carcinogens. Chromium exposures cannot be predicted from urinary excretion in one group of workers or for a single worker based on the exposure to excretion relationship in other groups. The toxicokinetics of nickel are summarized. A significant correlation between nickel in plasma and urinary nickel concentrations in exposed workers has been noted. High nickel concentrations have also been found in sweat, human parotid saliva and scalp hair, but these are not considered useful for biological monitoring. Plasma, urine or scalp hair nickel concentrations cannot be used to assess sensitivity as they do not differ between hypersensitive and non hypersensitive individuals. The author concludes that nickel exposure for a single worker cannot be estimated by biological monitoring; however, biological monitoring is useful in evaluating changes of exposure over time."
1516229,Norppa et al. 1990,Automation of mouse micronucleus test by flow cytometry and image analysis au - hayashi m,Biosis copyright: biol abs. rrm abstract bone marrow erythrocyte mitomycin c benzene 6 mercaptopurine benzo-a-pyrene n ethyl-n-nitrosourea bromodichloromethane potassium chromate chemical mutagen,Automation of mouse micronucleus test by flow cytometry and image analysis au - hayashi m Abs: Biosis copyright: biol abs. rrm abstract bone marrow erythrocyte mitomycin c benzene 6 mercaptopurine benzo-a-pyrene n ethyl-n-nitrosourea bromodichloromethane potassium chromate chemical mutagen
1516226,NIOSH 1988,"NIOSH Testimony on the Environmental Protection Agency's Proposed Rule on Proposed Prohibition of Hexavalent Chromium Chemicals in Comfort Cooling Towers by L. D. Reed, September 27, 1988","This testimony summarized the current position of NIOSH regarding the health effects from exposure to hexavalent chromium (18540299) (CrVI). The current published policy stated that only the insoluble forms of CrVI are potential human carcinogens. Since these facts were published, however, new scientific evidence has demonstrated the carcinogenic activity of soluble CrVI compounds in exposed animals and has also shown epidemiologic evidence indicating similar carcinogenicity among workers exposed to soluble CrVI compounds. NIOSH now recommends that OSHA consider all CrVI compounds as potential occupational carcinogens.","NIOSH Testimony on the Environmental Protection Agency's Proposed Rule on Proposed Prohibition of Hexavalent Chromium Chemicals in Comfort Cooling Towers by L. D. Reed, September 27, 1988 Abs: This testimony summarized the current position of NIOSH regarding the health effects from exposure to hexavalent chromium (18540299) (CrVI). The current published policy stated that only the insoluble forms of CrVI are potential human carcinogens. Since these facts were published, however, new scientific evidence has demonstrated the carcinogenic activity of soluble CrVI compounds in exposed animals and has also shown epidemiologic evidence indicating similar carcinogenicity among workers exposed to soluble CrVI compounds. NIOSH now recommends that OSHA consider all CrVI compounds as potential occupational carcinogens."
1516222,Niemela et al. 1995,Design Goals of Indoor Air Quality in Industrial Buildings,"In order to aid in the development of air quality guidelines for indoor environments, including industrial buildings, air quality measurements were taken in buildings with advanced control technology and compared with health based air quality guidelines. The register of occupational hygiene measurements from the Finnish Institute of Occupational Health was used to establish air quality guidelines, ventilation standards, measurements from occupational settings and expert evaluations of air quality control technologies. This data was combined with field measurements of air quality. Five categories of air quality based on contaminant levels such as inorganic dust, nickel (7440020) compounds, chromium (7440473) compounds, hexavalent chromium (18540299) compounds, oil mist, formaldehyde (50000) and nitrogen-dioxide (10102440) were presented, and industrial and human requirements based on these categories were tentatively set forth. Class one referred to clean air required for special processes (electronics industry, biotechnology environments), classes two, three and four represented good, standard and minimal industrial levels, respectively. Class five represented unoccupied spaces. The authors conclude that the present procedure can be used to set target levels for other contaminants.","Design Goals of Indoor Air Quality in Industrial Buildings Abs: In order to aid in the development of air quality guidelines for indoor environments, including industrial buildings, air quality measurements were taken in buildings with advanced control technology and compared with health based air quality guidelines. The register of occupational hygiene measurements from the Finnish Institute of Occupational Health was used to establish air quality guidelines, ventilation standards, measurements from occupational settings and expert evaluations of air quality control technologies. This data was combined with field measurements of air quality. Five categories of air quality based on contaminant levels such as inorganic dust, nickel (7440020) compounds, chromium (7440473) compounds, hexavalent chromium (18540299) compounds, oil mist, formaldehyde (50000) and nitrogen-dioxide (10102440) were presented, and industrial and human requirements based on these categories were tentatively set forth. Class one referred to clean air required for special processes (electronics industry, biotechnology environments), classes two, three and four represented good, standard and minimal industrial levels, respectively. Class five represented unoccupied spaces. The authors conclude that the present procedure can be used to set target levels for other contaminants."
1516220,Nicholls et al. 1998,Nmr spectroscopic based pattern recognition studies of hepato-and nephrotoxicity in the rat,Biosis copyright: biol abs. rrm meeting abstract rat strain-han wistar male strain-sprague-dawley toxicology digestive system urinary system nmr spectroscopy hepatotoxicity nephrotoxicity hydrazine thioacetamide allyl alcohol 2-bromoethanamine hydrochloride hexachlorobutadiene mercury ii chloride 1 1 2-trichloro-3 3 3-trifluoro-1-propene sodium chromate lead acetate adriamycin puromycin aminonucleoside analytical method digestive system disease toxicity urologic disease,Nmr spectroscopic based pattern recognition studies of hepato-and nephrotoxicity in the rat Abs: Biosis copyright: biol abs. rrm meeting abstract rat strain-han wistar male strain-sprague-dawley toxicology digestive system urinary system nmr spectroscopy hepatotoxicity nephrotoxicity hydrazine thioacetamide allyl alcohol 2-bromoethanamine hydrochloride hexachlorobutadiene mercury ii chloride 1 1 2-trichloro-3 3 3-trifluoro-1-propene sodium chromate lead acetate adriamycin puromycin aminonucleoside analytical method digestive system disease toxicity urologic disease
1516219,Newman and  Klein 2077,"Health Hazard Evaluation Report No. HETA-88-068-2077, Schmidt Cabinet Company, New Salisbury, Indiana","In response to a request from the Schmidt Cabinet Company (SIC-2434), New Salisbury, Indiana, an investigation was undertaken of the exhaust ventilation system and finishing room exposures. This firm manufactured kitchen cabinets and bathroom vanities. Approximately 90 workers were employed at the facility. The cabinets were made from various hard woods, and finished by spraying with a series of stains, sealers, and/or paints. Spraying was done in a spray booth. General area and personal breathing zone air samples were collected, and the ventilation system was evaluated. The authors conclude that a potential hazard existed due to airborne exposure to hexavalent chromium (7440473), formaldehyde (50000) and ethylene-glycol-monobutyl-ether (111762) in the cabinet finishing area. A lack of makeup air, ineffective use of exhaust ventilation systems, and uncontrolled contamination sources were several of the problems causing employee exposure. The authors recommend specific measures to minimize and reduce exposure to hexavalent chromium compounds and formaldehyde, and to improve the ventilation systems at this facility.","Health Hazard Evaluation Report No. HETA-88-068-2077, Schmidt Cabinet Company, New Salisbury, Indiana Abs: In response to a request from the Schmidt Cabinet Company (SIC-2434), New Salisbury, Indiana, an investigation was undertaken of the exhaust ventilation system and finishing room exposures. This firm manufactured kitchen cabinets and bathroom vanities. Approximately 90 workers were employed at the facility. The cabinets were made from various hard woods, and finished by spraying with a series of stains, sealers, and/or paints. Spraying was done in a spray booth. General area and personal breathing zone air samples were collected, and the ventilation system was evaluated. The authors conclude that a potential hazard existed due to airborne exposure to hexavalent chromium (7440473), formaldehyde (50000) and ethylene-glycol-monobutyl-ether (111762) in the cabinet finishing area. A lack of makeup air, ineffective use of exhaust ventilation systems, and uncontrolled contamination sources were several of the problems causing employee exposure. The authors recommend specific measures to minimize and reduce exposure to hexavalent chromium compounds and formaldehyde, and to improve the ventilation systems at this facility."
1516211,Navas and  Jimenez 1996,Review of chemiluminescent methods in food analysis,"BIOSIS COPYRIGHT: BIOL ABS. The purpose of the present review is to sketch out the scope of chemiluminescence in food analysis. Practical considerations are discussed. Specific applications to the determination of N-nitroso compounds, sugars, food oxidation, hormonal anabolics and metabolites, metals and other interesting compounds. There is also discussion on how alcohols, enzymes, etc. have been revised. Possibilities and limitations of the various reaction and detection systems are evaluated.","Review of chemiluminescent methods in food analysis Abs: BIOSIS COPYRIGHT: BIOL ABS. The purpose of the present review is to sketch out the scope of chemiluminescence in food analysis. Practical considerations are discussed. Specific applications to the determination of N-nitroso compounds, sugars, food oxidation, hormonal anabolics and metabolites, metals and other interesting compounds. There is also discussion on how alcohols, enzymes, etc. have been revised. Possibilities and limitations of the various reaction and detection systems are evaluated."
1516208,Nath and  Kumar 1987,Effect of hexavalent chromium on the carbohydrate metabolism of a freshwater tropical teleost colisa-fasciatus,Biosis copyright: biol abs. rrm toxicity muscle glycogen blood lactic acid,Effect of hexavalent chromium on the carbohydrate metabolism of a freshwater tropical teleost colisa-fasciatus Abs: Biosis copyright: biol abs. rrm toxicity muscle glycogen blood lactic acid
1516201,Namasivayam and  Yamuna 1995,Adsorption of chromium (VI) by a low-cost adsorbent: Biogas residual slurry,"BIOSIS COPYRIGHT: BIOL ABS. Ability of waste biogas residual slurry (BRS) to remove Cr (VI) from aqueous solutions was investigated. The influence of various parameters such as metal ion concentration, contact time, adsorbent dosage, adsorbent particle size, temperature and pH on the removal of Cr (VI) has been studied. The adsorption followed first order rate expression. The equilibrium data fit well into Langmuir and Freundlich isotherms. Adsorption was maximum at an initial pH of 1.51. Temperature studies showed that the adsorption process was endothermic in nature.","Adsorption of chromium (VI) by a low-cost adsorbent: Biogas residual slurry Abs: BIOSIS COPYRIGHT: BIOL ABS. Ability of waste biogas residual slurry (BRS) to remove Cr (VI) from aqueous solutions was investigated. The influence of various parameters such as metal ion concentration, contact time, adsorbent dosage, adsorbent particle size, temperature and pH on the removal of Cr (VI) has been studied. The adsorption followed first order rate expression. The equilibrium data fit well into Langmuir and Freundlich isotherms. Adsorption was maximum at an initial pH of 1.51. Temperature studies showed that the adsorption process was endothermic in nature."
1516200,Namasivayam and  Ranganathan 1993,Waste iron-chromium hydroxide as adsorbent for the removal of chromium(VI) from aqueous solution and chromium plating industry wastewater,"BIOSIS COPYRIGHT: BIOL ABS. Fe(III)r(III) hydroxide, a waste material from the fertilizer industry, has been used for the adsorption of Cr(VI) from aqueous solution, over a range of initial metal ion concentrations (5-30 mg litre-1), agitation time (1-180 min), adsorbent dosages (100-1200 mg per 50 ml), temperatures (24, 29 and 38êC) and pH values (4.5-10). The adsorption of Cr(VI) increased with the initial concentration of Cr(VI) and with temperature. The process of uptake follows both the Langmuir and the Freundlich isotherm models. The applicability of Lagergren and empirical kinetic models has also been investigated. Almost quantitative removal of Cr(VI) at 10 mg litre-1 in a 50-ml solution by 500 mg of adsorbent was found at an equilibrium ph of 5.6. The efficiency of chromium removal was also tested using wastewater from the chromium plating industry.","Waste iron-chromium hydroxide as adsorbent for the removal of chromium(VI) from aqueous solution and chromium plating industry wastewater Abs: BIOSIS COPYRIGHT: BIOL ABS. Fe(III)r(III) hydroxide, a waste material from the fertilizer industry, has been used for the adsorption of Cr(VI) from aqueous solution, over a range of initial metal ion concentrations (5-30 mg litre-1), agitation time (1-180 min), adsorbent dosages (100-1200 mg per 50 ml), temperatures (24, 29 and 38êC) and pH values (4.5-10). The adsorption of Cr(VI) increased with the initial concentration of Cr(VI) and with temperature. The process of uptake follows both the Langmuir and the Freundlich isotherm models. The applicability of Lagergren and empirical kinetic models has also been investigated. Almost quantitative removal of Cr(VI) at 10 mg litre-1 in a 50-ml solution by 500 mg of adsorbent was found at an equilibrium ph of 5.6. The efficiency of chromium removal was also tested using wastewater from the chromium plating industry."
1516199,Nakayasu et al. 1999,Comparative studies of the reduction behavior of chromium(VI) by humic substances and their precursors,"BIOSIS COPYRIGHT: BIOL ABS. Hexavalent chromium (Cr(VI)) is reduced by dissolved organic carbons (DOCs) such as humic substances, tannic acid (TA), and gallic acid (GA). The kinetic constants and the resulting chemical species after the reduction were compared with each other. The kinetic constants for GA and TA, which are model precursors of humic substances, were two to three orders of magnitude larger than those for the humic substances when these kinetic constants were expressed as a function of the molar concentration otometric data and gel permeation chromatography support this view.","Comparative studies of the reduction behavior of chromium(VI) by humic substances and their precursors Abs: BIOSIS COPYRIGHT: BIOL ABS. Hexavalent chromium (Cr(VI)) is reduced by dissolved organic carbons (DOCs) such as humic substances, tannic acid (TA), and gallic acid (GA). The kinetic constants and the resulting chemical species after the reduction were compared with each other. The kinetic constants for GA and TA, which are model precursors of humic substances, were two to three orders of magnitude larger than those for the humic substances when these kinetic constants were expressed as a function of the molar concentration otometric data and gel permeation chromatography support this view."
1516197,Nadzhafova 1979,"Effect of bichromate, caustic and calcined soda on the survival and respiration of Caspian Sea (USSR) shrimp (Palaemon adspersus)","HEEP COPYRIGHT: BIOL ABS. The toxicity of various concentrations (10, 20, 30, 40, 50, 75 and 100 mg/l) of chemical reagents (K2Cr2O7, caustic and calcined soda) used in oil drilling to P. adspersus was studied. Bichromate was the most toxic. Concentrations > 10 mg/l negatively affected shrimp survival. Phases of stimulation and suppression of respiration were observed with 10 mg/l bichromate concentrations. Stronger concentrations (40 mg/l) caused suppression of respiration. Sublethal concentrations of caustic and calcined soda and bichromate were 75, 100 and 40 mg/l, respectively. These doses contributed to the decrease in the active use of O2.","Effect of bichromate, caustic and calcined soda on the survival and respiration of Caspian Sea (USSR) shrimp (Palaemon adspersus) Abs: HEEP COPYRIGHT: BIOL ABS. The toxicity of various concentrations (10, 20, 30, 40, 50, 75 and 100 mg/l) of chemical reagents (K2Cr2O7, caustic and calcined soda) used in oil drilling to P. adspersus was studied. Bichromate was the most toxic. Concentrations > 10 mg/l negatively affected shrimp survival. Phases of stimulation and suppression of respiration were observed with 10 mg/l bichromate concentrations. Stronger concentrations (40 mg/l) caused suppression of respiration. Sublethal concentrations of caustic and calcined soda and bichromate were 75, 100 and 40 mg/l, respectively. These doses contributed to the decrease in the active use of O2."
1516195,Music 1986,Sorption of chromium-vi and chromium-iii on aluminum hydroxide,Biosis copyright: biol abs. rrm waste water sewage sludge pollution ph,Sorption of chromium-vi and chromium-iii on aluminum hydroxide Abs: Biosis copyright: biol abs. rrm waste water sewage sludge pollution ph
1516194,Music 1985,Sorption of chromium-iii and chromium-vi on lead sulfide,Biosis copyright: biol abs. rrm human toxicity water pollution environment,Sorption of chromium-iii and chromium-vi on lead sulfide Abs: Biosis copyright: biol abs. rrm human toxicity water pollution environment
1516189,Mueller 1980,Acute toxicity of potassium di chromate to daphnia-magna as a function of the water quality,Heep copyright: biol abs.,Acute toxicity of potassium di chromate to daphnia-magna as a function of the water quality Abs: Heep copyright: biol abs.
1516187,Mouradian and  Deitchman 2231,"Health Hazard Evaluation Report No. HETA-90-174-2231, Modern Materials Incorporated, Rochester, Indiana","In response to a request from the management of Modern Materials Incorporated (SIC-3479), Rochester, Indiana, possible chemical exposures associated with powder coating operations, specifically isocyanates used in some powder coatings, were evaluated. Air sampling indicated that the concentrations of most of the targeted chemicals were well below the Permissible Exposure Limits (PELs) and Recommended Exposure Limits (RELs). However, some exposures to epsilon-caprolactam (105602), formaldehyde (50000), and sulfur-dioxide (7446095) exceeded these limits. Conditions were observed which allowed dermal exposure to corrosives to occur, including hexavalent chromium (7440473). Inoperative eye washes, inadequate personal protective equipment, and apparent failure to meet communications requirements were also noted. The authors conclude that employees were exposed to potentially hazardous concentrations of aldehydes, epsilon-caprolactam, and sulfur-dioxide, and that there was a potential for hazardous exposures to other materials, and to unsafe conditions from inadequate use of safety devices and personal protective equipment. It was not possible to determine if workers had been exposed to unsafe levels of isocyanates or had developed isocyanate sensitization. The authors recommend specific measures to improve the conditions at this site.","Health Hazard Evaluation Report No. HETA-90-174-2231, Modern Materials Incorporated, Rochester, Indiana Abs: In response to a request from the management of Modern Materials Incorporated (SIC-3479), Rochester, Indiana, possible chemical exposures associated with powder coating operations, specifically isocyanates used in some powder coatings, were evaluated. Air sampling indicated that the concentrations of most of the targeted chemicals were well below the Permissible Exposure Limits (PELs) and Recommended Exposure Limits (RELs). However, some exposures to epsilon-caprolactam (105602), formaldehyde (50000), and sulfur-dioxide (7446095) exceeded these limits. Conditions were observed which allowed dermal exposure to corrosives to occur, including hexavalent chromium (7440473). Inoperative eye washes, inadequate personal protective equipment, and apparent failure to meet communications requirements were also noted. The authors conclude that employees were exposed to potentially hazardous concentrations of aldehydes, epsilon-caprolactam, and sulfur-dioxide, and that there was a potential for hazardous exposures to other materials, and to unsafe conditions from inadequate use of safety devices and personal protective equipment. It was not possible to determine if workers had been exposed to unsafe levels of isocyanates or had developed isocyanate sensitization. The authors recommend specific measures to improve the conditions at this site."
1516186,Móuller and  Janz 1992,Assessment of oxidative DNA damage in the oxyR-deficient SOS chromotest strain Escherichia coli PQ300,"The SOS chromotest is a simple short-term genotoxicity assay measuring the induction of gene sfiA in Escherichia coli K-12. The recent availability of SOS tester strains with additional mutations in DNA repair or protection systems allows testing of DNA damaging compounds for genotoxic specificity. E. coli PQ300 differs from the standard SOS tester strain PQ37 in that it contains an additional mutation in gene oxyR that renders it more sensitive to oxidative genotoxins. The generation of reactive oxygen intermediates (ROI) by hydroperoxides (H2O2, t-butyl hydroperoxide, cumene hydroperoxide), gamma-radiation, glucose oxidase, and xanthine oxidase resulted in a more vigorous SOS response in strain PQ300 compared to strain PQ37. PQ300 was also more sensitive than PQ37 for the detection of reducing agents such as ascorbic acid, cysteine, and glutathione, which also alter the redox status of the bacterial cells. However, intercalating agents (adriamycin, bleomycin, and mitomycin C) and the UV- and radiomimetic compound 4-nitroquinoline-1-oxide whose DNA damaging potential are known also to involve ROI did not show significant differences between strains PQ37 and PQ300. It is concluded that the oxyR-deficient strain PQ300 is useful for detecting certain classes of genotoxins that change the oxidative/antioxidative balance of tester bacteria in the SOS chromotest. TAX - ESCHERICHIA COLI,PQ300 TAX - ESCHERICHIA COLI,PQ37","Assessment of oxidative DNA damage in the oxyR-deficient SOS chromotest strain Escherichia coli PQ300 Abs: The SOS chromotest is a simple short-term genotoxicity assay measuring the induction of gene sfiA in Escherichia coli K-12. The recent availability of SOS tester strains with additional mutations in DNA repair or protection systems allows testing of DNA damaging compounds for genotoxic specificity. E. coli PQ300 differs from the standard SOS tester strain PQ37 in that it contains an additional mutation in gene oxyR that renders it more sensitive to oxidative genotoxins. The generation of reactive oxygen intermediates (ROI) by hydroperoxides (H2O2, t-butyl hydroperoxide, cumene hydroperoxide), gamma-radiation, glucose oxidase, and xanthine oxidase resulted in a more vigorous SOS response in strain PQ300 compared to strain PQ37. PQ300 was also more sensitive than PQ37 for the detection of reducing agents such as ascorbic acid, cysteine, and glutathione, which also alter the redox status of the bacterial cells. However, intercalating agents (adriamycin, bleomycin, and mitomycin C) and the UV- and radiomimetic compound 4-nitroquinoline-1-oxide whose DNA damaging potential are known also to involve ROI did not show significant differences between strains PQ37 and PQ300. It is concluded that the oxyR-deficient strain PQ300 is useful for detecting certain classes of genotoxins that change the oxidative/antioxidative balance of tester bacteria in the SOS chromotest. TAX - ESCHERICHIA COLI,PQ300 TAX - ESCHERICHIA COLI,PQ37"
1516184,Mortimer 1982,In-Depth Survey Report of American Airlines Plating Facility,"An indepth survey was conducted at the American Airlines Maintenance and Engineering Center Plating Facility (SIC-3720) on December 7 to 10, 1981. The survey was part of a NIOSH study evaluating measures to control occupational health hazards in the metal plating industry. The plating facility employed 25 workers and was primarily engaged in plating hard chromium (7440473), nickel (7440020), and cadmium (7440439) on aircraft engine and landing gear parts. Area and personal air samples were collected and analyzed for chromium, nickel, cadmium, and cyanide (74908). Ventilation air flow and tank dimensions were measured. Sulfuric-acid (7664939) (also a hazard in hard chrome plating operations) was also monitored. The OSHA standard for sulfuric-acid over an 8 hour time weighted average (TWA) was 1.0 milligram per cubic meter (mg/m3); for cadmium, the OSHA permissible exposure limit (PEL) was 0.2mg/m3; and for cyanide, 5mg/m3. OSHA PEL for nickel was 1mg/m3; and for chromic-acid and chromates, 0.5mg/m3 chromium for an 8 hours TWA. Personal exposures were all within recommended standards. Area concentrations around two tanks were relatively high. Covering the tank dramatically reduced the area concentrations. The author recommends mechanical supply of outside make up air into the shop to relieve negative pressure.","In-Depth Survey Report of American Airlines Plating Facility Abs: An indepth survey was conducted at the American Airlines Maintenance and Engineering Center Plating Facility (SIC-3720) on December 7 to 10, 1981. The survey was part of a NIOSH study evaluating measures to control occupational health hazards in the metal plating industry. The plating facility employed 25 workers and was primarily engaged in plating hard chromium (7440473), nickel (7440020), and cadmium (7440439) on aircraft engine and landing gear parts. Area and personal air samples were collected and analyzed for chromium, nickel, cadmium, and cyanide (74908). Ventilation air flow and tank dimensions were measured. Sulfuric-acid (7664939) (also a hazard in hard chrome plating operations) was also monitored. The OSHA standard for sulfuric-acid over an 8 hour time weighted average (TWA) was 1.0 milligram per cubic meter (mg/m3); for cadmium, the OSHA permissible exposure limit (PEL) was 0.2mg/m3; and for cyanide, 5mg/m3. OSHA PEL for nickel was 1mg/m3; and for chromic-acid and chromates, 0.5mg/m3 chromium for an 8 hours TWA. Personal exposures were all within recommended standards. Area concentrations around two tanks were relatively high. Covering the tank dramatically reduced the area concentrations. The author recommends mechanical supply of outside make up air into the shop to relieve negative pressure."
1516183,Mortimer 1982,"In-Depth Survey Report of Valley Chrome Platers, Bay City, Michigan","An indepth survey was conducted at Valley Chrome Platers (SIC-3471), Bay City, Michigan, in April and May 1981 to evaluate measures used to control occupational health hazards in with the metal plating industry. The two sided local exhaust ventilation systems for the hard chrome (7440473) (Cr) plating tanks were evaluated on eight tanks. Area and personal air samples were collected for Cr, hexavalent-chromium (18540299), and sulfuric-acid (7664939). Ventilation airflow and tank dimensions were measured. Workers wore hard hats, safety glasses, and steel toed shoes. Gloves were used much of the time. Work clothes were supplied and cleaned by the shop. All large pieces were lifted by powered, overhead hoists. Ambient contaminant concentrations were lowered by the make up air provided, allowing the local exhaust ventilation to work at maximum efficiency. Personal time weighted averages of Cr and sulfuric-acid concentrations were below both OSHA permissible exposure limits and NIOSH standards. Sampling did not correlate well with plating activity, indicating the effective limitation of acid mists into the air. The author recommends the use of small floating plastic spheres over tank surfaces to control plating emissions.","In-Depth Survey Report of Valley Chrome Platers, Bay City, Michigan Abs: An indepth survey was conducted at Valley Chrome Platers (SIC-3471), Bay City, Michigan, in April and May 1981 to evaluate measures used to control occupational health hazards in with the metal plating industry. The two sided local exhaust ventilation systems for the hard chrome (7440473) (Cr) plating tanks were evaluated on eight tanks. Area and personal air samples were collected for Cr, hexavalent-chromium (18540299), and sulfuric-acid (7664939). Ventilation airflow and tank dimensions were measured. Workers wore hard hats, safety glasses, and steel toed shoes. Gloves were used much of the time. Work clothes were supplied and cleaned by the shop. All large pieces were lifted by powered, overhead hoists. Ambient contaminant concentrations were lowered by the make up air provided, allowing the local exhaust ventilation to work at maximum efficiency. Personal time weighted averages of Cr and sulfuric-acid concentrations were below both OSHA permissible exposure limits and NIOSH standards. Sampling did not correlate well with plating activity, indicating the effective limitation of acid mists into the air. The author recommends the use of small floating plastic spheres over tank surfaces to control plating emissions."
1516182,Mortimer and  Miller 1994,"Susceptibility of larval and juvenile instars of the sand crab, Portunus pelagicus (L.), to sea water contaminated by chromium, nickel or copper","BIOSIS COPYRIGHT: BIOL ABS. The acute toxicities of Cu2+, Ni2+ and Cr(VI) in sea water to larval life stages of the sand crab, Portunus pelagicus, were determined in a laboratory study and compared with published data for the toxicity of heavy metal cations to this species. This showed the relative acute toxicities to be in the order Cu2+ > Cd2+ \ Zn2+ > Ni2+ > Cr(VI). Sublethal effects attributable to exposure to sea water contaminated by some of these cations were investigated for both larval and juvenile crab life stages. The effects quantified were inhibition of larval moulting, increase in the duration of development period, and reduced size achieved by successive juvenile crab instars. In each case, the chronic levels of cation contamination in seawater associated with these effects exceeded the Australian guidelines for the protection of marine aquatic ecosystems, but in some cases the safety margin was less than an order of magnitude. In addition, bioconcentration relationships f","Susceptibility of larval and juvenile instars of the sand crab, Portunus pelagicus (L.), to sea water contaminated by chromium, nickel or copper Abs: BIOSIS COPYRIGHT: BIOL ABS. The acute toxicities of Cu2+, Ni2+ and Cr(VI) in sea water to larval life stages of the sand crab, Portunus pelagicus, were determined in a laboratory study and compared with published data for the toxicity of heavy metal cations to this species. This showed the relative acute toxicities to be in the order Cu2+ > Cd2+ \ Zn2+ > Ni2+ > Cr(VI). Sublethal effects attributable to exposure to sea water contaminated by some of these cations were investigated for both larval and juvenile crab life stages. The effects quantified were inhibition of larval moulting, increase in the duration of development period, and reduced size achieved by successive juvenile crab instars. In each case, the chronic levels of cation contamination in seawater associated with these effects exceeded the Australian guidelines for the protection of marine aquatic ecosystems, but in some cases the safety margin was less than an order of magnitude. In addition, bioconcentration relationships f"
1516181,Moropoulou et al. 1998,"Atmospheric deposition as decay factor for the demeter sanctuary ruins in the industrial atmosphere of Eleusis, Greece","BIOSIS COPYRIGHT: BIOL ABS. The action of air pollution and environmental conditions on the weathering of historical monuments has been investigated for the site of the Demeter Sanctuary (1500 BC) in Eleusis, Greece. Total deposition and aerosols were analysed in relation to the concentration of elements in the various types of weathered stone crusts. The objective of the study was the evaluation of the origin of the elements and ions determined in aerosols and total deposition and to relate these to possible sources (soil, underlying rock, marine spray and anthropogenic activities) using enrichment factors.","Atmospheric deposition as decay factor for the demeter sanctuary ruins in the industrial atmosphere of Eleusis, Greece Abs: BIOSIS COPYRIGHT: BIOL ABS. The action of air pollution and environmental conditions on the weathering of historical monuments has been investigated for the site of the Demeter Sanctuary (1500 BC) in Eleusis, Greece. Total deposition and aerosols were analysed in relation to the concentration of elements in the various types of weathered stone crusts. The objective of the study was the evaluation of the origin of the elements and ions determined in aerosols and total deposition and to relate these to possible sources (soil, underlying rock, marine spray and anthropogenic activities) using enrichment factors."
1516179,Moreton 1986,The case for standardization of tests for welding fume emission rate and chemical composition determination,Biosis copyright: biol abs. rrm health and safety at work act uk environmental surveillance regulation work environment air pollution hazardous materials metal industry,The case for standardization of tests for welding fume emission rate and chemical composition determination Abs: Biosis copyright: biol abs. rrm health and safety at work act uk environmental surveillance regulation work environment air pollution hazardous materials metal industry
1516178,Morales-Rubio 1996,Modern strategies for the rapid determination of metals in sewage sludges. AU - DE LA GUARDIA M,"BIOSIS COPYRIGHT: BIOL ABS. The state-of-the-art of the analysis of metals in sewage sludges is presented, with special attention to aspects such as sample preparation and the fast analytical control of as many elements as possible in a single sample. The need for simple, accurate and precise procedures for evaluating the toxicity of sewage sludges and their suitability for agricultural use is referred also to the development of speciation strategies. For the latter purpose the combination of chromatography and atomic spectrometry will be helpful for identifying the chemical forms of metals in sewage sludges, but this strategy must be combined with the use of mild and quantitative methods for fast and selective leaching of the different chemical species without modifying the composition of samples.","Modern strategies for the rapid determination of metals in sewage sludges. AU - DE LA GUARDIA M Abs: BIOSIS COPYRIGHT: BIOL ABS. The state-of-the-art of the analysis of metals in sewage sludges is presented, with special attention to aspects such as sample preparation and the fast analytical control of as many elements as possible in a single sample. The need for simple, accurate and precise procedures for evaluating the toxicity of sewage sludges and their suitability for agricultural use is referred also to the development of speciation strategies. For the latter purpose the combination of chromatography and atomic spectrometry will be helpful for identifying the chemical forms of metals in sewage sludges, but this strategy must be combined with the use of mild and quantitative methods for fast and selective leaching of the different chemical species without modifying the composition of samples."
1516166,Montgomery and  Stiff 1971,Differentiation of chemical states of toxic species especially cyanide and copper in water,Heep copyright: biol abs. fish hydrogen cyanide chromium copper carbon di oxide hydrogen cyanide,Differentiation of chemical states of toxic species especially cyanide and copper in water Abs: Heep copyright: biol abs. fish hydrogen cyanide chromium copper carbon di oxide hydrogen cyanide
1516165,Montaldi et al. 1987,Solubilization by nitrilotriacetic acid nta of genetically active chromium-vi and lead-ii from insoluble metal compounds,Biosis copyright: biol abs. rrm environmental pollution sister chromatid exchange household detergent,Solubilization by nitrilotriacetic acid nta of genetically active chromium-vi and lead-ii from insoluble metal compounds Abs: Biosis copyright: biol abs. rrm environmental pollution sister chromatid exchange household detergent
1516164,Montaldi et al. 1988,Solubilization by nitrilotriacetic acid nta of genetically active chromium-vi and lead-ii from insoluble metal compounds,Biosis copyright: biol abs. rrm abstract cho cells toxicodynamics sister chromatid exchange genotoxicity,Solubilization by nitrilotriacetic acid nta of genetically active chromium-vi and lead-ii from insoluble metal compounds Abs: Biosis copyright: biol abs. rrm abstract cho cells toxicodynamics sister chromatid exchange genotoxicity
1516161,Mohammad et al. 1993,Planar layer chromatography in the analysis of inorganic pollutants,Biosis copyright: biol abs. rrm analytical method,Planar layer chromatography in the analysis of inorganic pollutants Abs: Biosis copyright: biol abs. rrm analytical method
1516158,Mitra et al. 1998,Evaluating composite ion exchangers (CIX) for improved stability of anaerobic biological reactors,"BIOSIS COPYRIGHT: BIOL ABS. An extensive laboratory study demonstrated that the stability of anaerobic biological processes can be improved and the process failure prevented by retaining specialty functionalized polymers inside the reactors. Such functionalized polymers, referred to as composite ion exchanger (CIX), are essentially microbeads of chelating exchanger encapsulated in fibrous, cloth-like polytetrafluoroethylene or Teflon. During the course of the investigation, severe stresses were introduced into a train of anaerobic reactors through organic and heavy-metal overloading of the feed. The reactors containing CIX successfully survived the stresses by dissipating the inhibitory hydrogen ions and dissolved heavy metals from the aqueous phase. The reactors containing no CIX always failed under stress conditions, all other conditions remaining identical. The CIXs were found to be chemically stable, durable, did not require any intermittent cleaning or regeneration, and occupied less than one","Evaluating composite ion exchangers (CIX) for improved stability of anaerobic biological reactors Abs: BIOSIS COPYRIGHT: BIOL ABS. An extensive laboratory study demonstrated that the stability of anaerobic biological processes can be improved and the process failure prevented by retaining specialty functionalized polymers inside the reactors. Such functionalized polymers, referred to as composite ion exchanger (CIX), are essentially microbeads of chelating exchanger encapsulated in fibrous, cloth-like polytetrafluoroethylene or Teflon. During the course of the investigation, severe stresses were introduced into a train of anaerobic reactors through organic and heavy-metal overloading of the feed. The reactors containing CIX successfully survived the stresses by dissipating the inhibitory hydrogen ions and dissolved heavy metals from the aqueous phase. The reactors containing no CIX always failed under stress conditions, all other conditions remaining identical. The CIXs were found to be chemically stable, durable, did not require any intermittent cleaning or regeneration, and occupied less than one"
1516156,Misra and  Wetterhahn 1994,Effect of dietary ascorbic acid and buthionine sulfoximine on chromiumvi-induced damage in a mutant rat unable to synthesize ascorbic acid,Biosis copyright: biol abs. rrm meeting abstract carcinogenesis,Effect of dietary ascorbic acid and buthionine sulfoximine on chromiumvi-induced damage in a mutant rat unable to synthesize ascorbic acid Abs: Biosis copyright: biol abs. rrm meeting abstract carcinogenesis
1516155,Misra et al. 1990,Transformation of added heavy metals in soils under flooded condition,"BIOSIS COPYRIGHT: BIOL ABS. The transformation of added Zn, Cu, Ni, Cd, Pb and Cr (VI) in Inceptisol, Vertisol and two Ultisols were studied in incubation (0-120 days) experiment under flooded condition. The extractability (DTPA) of the transformed metals depended on the metals and nature of soil; however, it declined with the period of incubation. Among the metals, the extractability of Cd was the highest and Cr (VI) the least in all the soils upon initial flooding. The reversion of Pb into non-extractable form was relatively slow in all the soils, except in the Inceptisol. The metal Cr(VI) was reverted to non-extractable form very fast in all the soils, barring the Ultisol of Bhubaneswar, where it persisted even after 120 days of flooding. The reversion of other metals was slow in the soil, thus indicating the potential toxicity of these metals.","Transformation of added heavy metals in soils under flooded condition Abs: BIOSIS COPYRIGHT: BIOL ABS. The transformation of added Zn, Cu, Ni, Cd, Pb and Cr (VI) in Inceptisol, Vertisol and two Ultisols were studied in incubation (0-120 days) experiment under flooded condition. The extractability (DTPA) of the transformed metals depended on the metals and nature of soil; however, it declined with the period of incubation. Among the metals, the extractability of Cd was the highest and Cr (VI) the least in all the soils upon initial flooding. The reversion of Pb into non-extractable form was relatively slow in all the soils, except in the Inceptisol. The metal Cr(VI) was reverted to non-extractable form very fast in all the soils, barring the Ultisol of Bhubaneswar, where it persisted even after 120 days of flooding. The reversion of other metals was slow in the soil, thus indicating the potential toxicity of these metals."
1516154,Mishra et al. 1997,A study on the uptake of trivalent and hexavalent chromium by paddy (Oryza sativa): Possible chemical modifications in rhizosphere,"BIOSIS COPYRIGHT: BIOL ABS. The uptake and translocation of chromium by paddy (Oryza sativa L. Arbario) was studied using radiotracers. Chromium was supplied as Cr III and Cr VI through irrigation water and plants were grown in sand and soil culture. The uptake of chromium for both the oxidation states and culture types was found to increase more or less linearly with the increase in chromium concentration though with different slopes. The rate of increase of the uptake when compared to the increase in feed concentration indicates that the uptake by roots is mediated possibly through a passive mechanism. For a given concentration of feed, values of chromium in mug g-1 dry matter in shoot and grain did not vary significantly either for different oxidation states of feed chromium or culture type. The order of uptake for paddy shows a considerably different pattern when compared to onion, maize and groundnut. This has been qualitatively explained on the basis of the different chemistry of chromium i","A study on the uptake of trivalent and hexavalent chromium by paddy (Oryza sativa): Possible chemical modifications in rhizosphere Abs: BIOSIS COPYRIGHT: BIOL ABS. The uptake and translocation of chromium by paddy (Oryza sativa L. Arbario) was studied using radiotracers. Chromium was supplied as Cr III and Cr VI through irrigation water and plants were grown in sand and soil culture. The uptake of chromium for both the oxidation states and culture types was found to increase more or less linearly with the increase in chromium concentration though with different slopes. The rate of increase of the uptake when compared to the increase in feed concentration indicates that the uptake by roots is mediated possibly through a passive mechanism. For a given concentration of feed, values of chromium in mug g-1 dry matter in shoot and grain did not vary significantly either for different oxidation states of feed chromium or culture type. The order of uptake for paddy shows a considerably different pattern when compared to onion, maize and groundnut. This has been qualitatively explained on the basis of the different chemistry of chromium i"
1516153,Miranda and  Castillo 1998,Resistance to antibiotic and heavy metals of motile aeromonads from Chilean freshwater,"BIOSIS COPYRIGHT: BIOL ABS. In this work the resistance of 172 motile Aeromonas isolates recovered from raw drinking water supplies (56), irrigation waters (60) and runoff waters receiving sewage (56), to some antibiotics and heavy metals was investigated by agar diffusion and agar dilution methods. A high proportion of isolates from all water sources showed resistance to carbenicillin, erythromycin, streptomycin, cephradine and cadmium, and susceptibility to chloramphenicol, kanamycin, gentamicin, tetracycline, nalidixic acid, trimethoprim-sulphametoxazole and chromium. No amikacin-resistant Aeromonas were recovered. No relationship was found between antimicrobial resistance and Aeromonas species, with the exception of cephradine, that exhibited a significantly higher activity against the A. sobria isolates than the other Aeromonas species (P < 0.05). Moderately polluted waters showed lower antibiotic multiresistance and metal susceptibility than unpolluted and highly polluted ones. Although","Resistance to antibiotic and heavy metals of motile aeromonads from Chilean freshwater Abs: BIOSIS COPYRIGHT: BIOL ABS. In this work the resistance of 172 motile Aeromonas isolates recovered from raw drinking water supplies (56), irrigation waters (60) and runoff waters receiving sewage (56), to some antibiotics and heavy metals was investigated by agar diffusion and agar dilution methods. A high proportion of isolates from all water sources showed resistance to carbenicillin, erythromycin, streptomycin, cephradine and cadmium, and susceptibility to chloramphenicol, kanamycin, gentamicin, tetracycline, nalidixic acid, trimethoprim-sulphametoxazole and chromium. No amikacin-resistant Aeromonas were recovered. No relationship was found between antimicrobial resistance and Aeromonas species, with the exception of cephradine, that exhibited a significantly higher activity against the A. sobria isolates than the other Aeromonas species (P < 0.05). Moderately polluted waters showed lower antibiotic multiresistance and metal susceptibility than unpolluted and highly polluted ones. Although"
1516151,Minoia et al. 1984,Determination of hexavalent chromium in bile by electrothermal atomization atomic-absorption spectrophotometry and liquid anion-exchange separation,HEEP COPYRIGHT: BIOL ABS. An electrothermal atomization atomic absorption spectrophotometric (ETA-AAS) method is reported for the selective determination of Cr(VI) in rat bile. The method gives reproducible results (the c.v. (coefficient of variation) ranged from 3.6% to 4.1% for low and high Cr(VI) bile samples respectively) and the recovery data are high varying from 98.6-98.7%. No detectable amounts of Cr(VI) ( < 0.2 ppb) suggests that available Cr in rat bile samples was present as Cr(III).,Determination of hexavalent chromium in bile by electrothermal atomization atomic-absorption spectrophotometry and liquid anion-exchange separation Abs: HEEP COPYRIGHT: BIOL ABS. An electrothermal atomization atomic absorption spectrophotometric (ETA-AAS) method is reported for the selective determination of Cr(VI) in rat bile. The method gives reproducible results (the c.v. (coefficient of variation) ranged from 3.6% to 4.1% for low and high Cr(VI) bile samples respectively) and the recovery data are high varying from 98.6-98.7%. No detectable amounts of Cr(VI) ( < 0.2 ppb) suggests that available Cr in rat bile samples was present as Cr(III).
1516145,Miller et al. 1988,Changes in nuclear protein-dna interaction caused by potassium chromate,Biosis copyright: biol abs. rrm abstract carcinogens,Changes in nuclear protein-dna interaction caused by potassium chromate Abs: Biosis copyright: biol abs. rrm abstract carcinogens
1516144,Milacic and  Stupar 1995,Fractionation and oxidation of chromium in tannery waste- and sewage sludge-amended soils,"BIOSIS COPYRIGHT: BIOL ABS. Clay, sand and peat soils were mixed with tannery waste so that the final concentrations of total chromium were between 1500 and 2000 mug g-1 and with sewage sludge where the final concentrations of total chromium ranged from 170 to 200 mug g-1. The experiments was carried out for 2 years under atmospheric conditions. Fractionation of chromium was studied in these soils employing a sequential extraction procedure and oxidation of chromium by measurement of chromium(VI) in the water-soluble fraction. The results of fractionation studies in tannery waste-amended soils indicated that 5 months after the start of the experiment up to 1.1% of total added chromium was oxidized in clay, 0.45% in sand, and only 0.03% in peat soil. The concentration of the water-soluble chromium and chromium(VI) decreased in further continuation of the experiment since chromium was redistributed to more sparingly soluble fractions of soils. The process of chromium oxidation was not observed in se","Fractionation and oxidation of chromium in tannery waste- and sewage sludge-amended soils Abs: BIOSIS COPYRIGHT: BIOL ABS. Clay, sand and peat soils were mixed with tannery waste so that the final concentrations of total chromium were between 1500 and 2000 mug g-1 and with sewage sludge where the final concentrations of total chromium ranged from 170 to 200 mug g-1. The experiments was carried out for 2 years under atmospheric conditions. Fractionation of chromium was studied in these soils employing a sequential extraction procedure and oxidation of chromium by measurement of chromium(VI) in the water-soluble fraction. The results of fractionation studies in tannery waste-amended soils indicated that 5 months after the start of the experiment up to 1.1% of total added chromium was oxidized in clay, 0.45% in sand, and only 0.03% in peat soil. The concentration of the water-soluble chromium and chromium(VI) decreased in further continuation of the experiment since chromium was redistributed to more sparingly soluble fractions of soils. The process of chromium oxidation was not observed in se"
1516142,Mikalsen 1990,Effects of heavy metal ions on intercellular communication in Syrian hamster embryo cells,"Several heavy metal salts [NiSO4, Cd(CH3COO)2, Pb(CH3COO)2, K2CrO4, CrCl3] were examined for their effects on intercellular communication in primary Syrian hamster embryo (SHE) cells and in the 12-O-tetradecanoyl-phorbol-13-acetate (TPA)-sensitive SHE cell line BPNi. Two exposure regimes were used: the standard regime where the exposure occurred after the cells had grown to confluence; and a non-standard regime where a high number of cells were seeded In a medium containing the metal salts. None of the chemicals were potent inhibitors of communication, i.e. effects were only found at concentrations that were non-compatible with long-term survival of the cells. NISO4 inhibited communication in both regimes and in both cell types, but the effect was more pronounced for BPNi cells in the non-standard regime. K2CrO4 inhibited communication In the non-standard regime in both cell types, but significantly increased communication in the standard regime In BPNi cells. Similar effects were not found with CrCl3 or KCl. Thus, they were due to the properties of the CrO42? ion. K2CrO4 upregulated communication in TPA-exposed BPNi cells. A high concentration of SO did not Influence the K2CrO4 inhibition in the non-standard regime, but it significantly inhibited the K2CrO4-induced increase in communication in the standard regime in BPNi cells. This 5Uggests that K2CrO4 acts through two different mechanisms in the two exposure regimes. The CrO42?-sensitive site that causes enhancement of communication in the standard regime is probably intracellular, while the site causing CrO42? inhibition in the fonnation of gapjunctional communication in the non-standard regime is most likely to be extracellular.","Effects of heavy metal ions on intercellular communication in Syrian hamster embryo cells Abs: Several heavy metal salts [NiSO4, Cd(CH3COO)2, Pb(CH3COO)2, K2CrO4, CrCl3] were examined for their effects on intercellular communication in primary Syrian hamster embryo (SHE) cells and in the 12-O-tetradecanoyl-phorbol-13-acetate (TPA)-sensitive SHE cell line BPNi. Two exposure regimes were used: the standard regime where the exposure occurred after the cells had grown to confluence; and a non-standard regime where a high number of cells were seeded In a medium containing the metal salts. None of the chemicals were potent inhibitors of communication, i.e. effects were only found at concentrations that were non-compatible with long-term survival of the cells. NISO4 inhibited communication in both regimes and in both cell types, but the effect was more pronounced for BPNi cells in the non-standard regime. K2CrO4 inhibited communication In the non-standard regime in both cell types, but significantly increased communication in the standard regime In BPNi cells. Similar effects were not found with CrCl3 or KCl. Thus, they were due to the properties of the CrO42? ion. K2CrO4 upregulated communication in TPA-exposed BPNi cells. A high concentration of SO did not Influence the K2CrO4 inhibition in the non-standard regime, but it significantly inhibited the K2CrO4-induced increase in communication in the standard regime in BPNi cells. This 5Uggests that K2CrO4 acts through two different mechanisms in the two exposure regimes. The CrO42?-sensitive site that causes enhancement of communication in the standard regime is probably intracellular, while the site causing CrO42? inhibition in the fonnation of gapjunctional communication in the non-standard regime is most likely to be extracellular."
1516138,Micera and  Dessi 1988,Chromium adsorption by plant roots and formation of long-lived chromium-v species an ecological hazard,Biosis copyright: biol abs. rrm allium-sativum mutagenesis carcinogenesis ligand binding heavy metal pollution,Chromium adsorption by plant roots and formation of long-lived chromium-v species an ecological hazard Abs: Biosis copyright: biol abs. rrm allium-sativum mutagenesis carcinogenesis ligand binding heavy metal pollution
1516137,Merrin et al. 1998,Biosorption of chromium VI using Rhizopus arrhizus,"BIOSIS COPYRIGHT: BIOL ABS. Adsorption intensity of non-living Rhizopus arrhizus biomass for chromium (VI) from aqueous solution has been investigated. Influence of pH, contact time, absorbent to liquid ratio was studied. Maximum adsorption was noticed at pH 2 with 8 hr contact time. Biomass (1%) showed 98% adsorption of chromium when contacted with chromium solution (100 mg). Freundlich adsorption isotherm was constructed and adsorption intensity (1/n) and capacity (log K) were determined.","Biosorption of chromium VI using Rhizopus arrhizus Abs: BIOSIS COPYRIGHT: BIOL ABS. Adsorption intensity of non-living Rhizopus arrhizus biomass for chromium (VI) from aqueous solution has been investigated. Influence of pH, contact time, absorbent to liquid ratio was studied. Maximum adsorption was noticed at pH 2 with 8 hr contact time. Biomass (1%) showed 98% adsorption of chromium when contacted with chromium solution (100 mg). Freundlich adsorption isotherm was constructed and adsorption intensity (1/n) and capacity (log K) were determined."
1516134,Melo Oliveira et al. 1992,Anaerobic bioreduction of toxic hexavalent chromium in enrichment cultures from soil samples,Biosis copyright: biol abs. rrm abstract bacteria pollution biodegradation analytical method,Anaerobic bioreduction of toxic hexavalent chromium in enrichment cultures from soil samples Abs: Biosis copyright: biol abs. rrm abstract bacteria pollution biodegradation analytical method
1516133,Meisch and  Schmitt-Beckmann 1979,Influence of chromium III and chromium VI on 2 Chlorella strains,"HEEP COPYRIGHT: BIOL ABS. The influence of several Cr compounds (0-2 mg Cr/l as KCr(SO4)2, Cr(III)-EDTA, CrLIII)-glycine, or K2Cr2O7) were studied with the unicellular green algae C. pyrenoidosa 211-8b and Chlorella WR 1, the latter being a wild strain isolated from a Cr-polluted surface water. The algae were cultivated either in permanent light or under a light/dark regime (16:8 h). Several distinct effects of the trace metal on algal metabolism were detected. At low Cr concentrations (0.1-0.5 mg Cr/l) stimulation of growth and photosynthetic O2 evolution, a general depression of chlorophyll synthesis and an acceleration of cell division, paralleled by a decrease in cell volume, were found. Some of these effects were not always expressed in the wild strain; this alga was less influenced by Cr(III) under light/dark changing conditions. The effect of adaptation of Chlorella WR 1 to its natural environment upon Cr toxicity is discussed.","Influence of chromium III and chromium VI on 2 Chlorella strains Abs: HEEP COPYRIGHT: BIOL ABS. The influence of several Cr compounds (0-2 mg Cr/l as KCr(SO4)2, Cr(III)-EDTA, CrLIII)-glycine, or K2Cr2O7) were studied with the unicellular green algae C. pyrenoidosa 211-8b and Chlorella WR 1, the latter being a wild strain isolated from a Cr-polluted surface water. The algae were cultivated either in permanent light or under a light/dark regime (16:8 h). Several distinct effects of the trace metal on algal metabolism were detected. At low Cr concentrations (0.1-0.5 mg Cr/l) stimulation of growth and photosynthetic O2 evolution, a general depression of chlorophyll synthesis and an acceleration of cell division, paralleled by a decrease in cell volume, were found. Some of these effects were not always expressed in the wild strain; this alga was less influenced by Cr(III) under light/dark changing conditions. The effect of adaptation of Chlorella WR 1 to its natural environment upon Cr toxicity is discussed."
1516132,Mehra and  Frankenberger 1989,Single-column ion-chromatographic determination of chromium-vi in aqueous soil and sludge extracts,Biosis copyright: biol abs. rrm,Single-column ion-chromatographic determination of chromium-vi in aqueous soil and sludge extracts Abs: Biosis copyright: biol abs. rrm
1516125,Mccaffrey and  Hamilton 1990,Differential effects of methyl methanesulfonate on constitutive and inducible gene expression in-vivo,Biosis copyright: biol abs. rrm abstract chick embryo liver carcinogen chromium-vi aminolevulinic acid synthase steady-state messenger rna levels dna damage,Differential effects of methyl methanesulfonate on constitutive and inducible gene expression in-vivo Abs: Biosis copyright: biol abs. rrm abstract chick embryo liver carcinogen chromium-vi aminolevulinic acid synthase steady-state messenger rna levels dna damage
1516124,Mazierski 1994,Effect of chromium (CrVI) on the growth rate of denitrifying bacteria,"BIOSIS COPYRIGHT: BIOL ABS. The effect of hexavalent chromium on the growth rate of denitrifying bacteria was studied under chemostatic cultivation. Chromium (CrVI) in the range to 0.6 mg/l decreases the maximum growth rate mumax and the Monod constant Ks. Its effect can be described by a generalized form of the kinetic equation in the form: The values of mumax, Ks, p,q and r were estimated as 0.3929 h-1, 20.992 mg/l, -0.7008 l/mg respectively.","Effect of chromium (CrVI) on the growth rate of denitrifying bacteria Abs: BIOSIS COPYRIGHT: BIOL ABS. The effect of hexavalent chromium on the growth rate of denitrifying bacteria was studied under chemostatic cultivation. Chromium (CrVI) in the range to 0.6 mg/l decreases the maximum growth rate mumax and the Monod constant Ks. Its effect can be described by a generalized form of the kinetic equation in the form: The values of mumax, Ks, p,q and r were estimated as 0.3929 h-1, 20.992 mg/l, -0.7008 l/mg respectively."
1516122,Mautner 1980,Arsenic and chromium(VI) content in drinking water of the country (Bulgaria) and its contamination with them,"HEEP COPYRIGHT: BIOL ABS. Ar and Cr6+ content in drinking water of 74% of the settlements with central water supply used by 89.2% of the whole population of the country was studied. As and Cr6+ were present mainly in microamounts and a high percent of the settlements used water without Cr6+, 79.2% and without As 43.3%. As was not established in overallowable concentrations of potable water (MAC (maximum allowable concentration) = 0.050 mg/dm3) but up to 0.010 mg/dm3 was found in the water of 51.3% of the settlements and > 0.010-0.050 mg/dm3 in 5.4%. Cr6+ was found in drinking water in concentrations over the allowable norm inthe limits of the allowable norm in 19.3%. Overallowable concentrations of Cr6+ were established in some local sources (wells, fountains with caught waters) in some of the investigated settlements. Some were 2- to 3-fold","Arsenic and chromium(VI) content in drinking water of the country (Bulgaria) and its contamination with them Abs: HEEP COPYRIGHT: BIOL ABS. Ar and Cr6+ content in drinking water of 74% of the settlements with central water supply used by 89.2% of the whole population of the country was studied. As and Cr6+ were present mainly in microamounts and a high percent of the settlements used water without Cr6+, 79.2% and without As 43.3%. As was not established in overallowable concentrations of potable water (MAC (maximum allowable concentration) = 0.050 mg/dm3) but up to 0.010 mg/dm3 was found in the water of 51.3% of the settlements and > 0.010-0.050 mg/dm3 in 5.4%. Cr6+ was found in drinking water in concentrations over the allowable norm inthe limits of the allowable norm in 19.3%. Overallowable concentrations of Cr6+ were established in some local sources (wells, fountains with caught waters) in some of the investigated settlements. Some were 2- to 3-fold"
1516121,Matsumoto et al. 1992,Physicochemical processes,Biosis copyright: biol abs. rrm review microorganism waste management bioreactor activated sludge wastewater treatment membrane process organics heavy metals mercury mathematical model computer simulation,Physicochemical processes Abs: Biosis copyright: biol abs. rrm review microorganism waste management bioreactor activated sludge wastewater treatment membrane process organics heavy metals mercury mathematical model computer simulation
1516117,Martinez-Pacheco and  Cervantes 1995,Hexavalent-chromium reduction by a chromate-resistant Bacillus sp. strain. AU - CAMPOS J,"BIOSIS COPYRIGHT: BIOL ABS. Bacillus strain QCl-2, isolated from a chromium-polluted zone, was selected by its high ability to both tolerate and reduce hexavalent chromium (Cr(VI)) to less-toxic trivalent chromium (Cr(III)). Cell suspensions of strain QC1-2 rapidly reduced Cr(VI), in both aerobic and anaerobic conditions, to CR(III) which remained in the supernatant. Cr(VI) reduction was dependent on the addition of glucose but sulfate, an inhibitor of chromate transport. had no effect. Studies with permeabilized cells and cell extracts showed that the Cr(VI) reductase of strain QC1-2 is a soluble NADH-dependent enzyme.","Hexavalent-chromium reduction by a chromate-resistant Bacillus sp. strain. AU - CAMPOS J Abs: BIOSIS COPYRIGHT: BIOL ABS. Bacillus strain QCl-2, isolated from a chromium-polluted zone, was selected by its high ability to both tolerate and reduce hexavalent chromium (Cr(VI)) to less-toxic trivalent chromium (Cr(III)). Cell suspensions of strain QC1-2 rapidly reduced Cr(VI), in both aerobic and anaerobic conditions, to CR(III) which remained in the supernatant. Cr(VI) reduction was dependent on the addition of glucose but sulfate, an inhibitor of chromate transport. had no effect. Studies with permeabilized cells and cell extracts showed that the Cr(VI) reductase of strain QC1-2 is a soluble NADH-dependent enzyme."
1516115,Marthinsen et al. 1983,Response Of Bovine Alveolar Macrophages In Vitro To Welding Fume Particles AU - White LR,"The effects of welding fume particles on bovine alveolar macrophage (AM) survival and enzyme production were studied. AM cultures, with or without bovine serum albumin, were incubated for 17 to 20 hours with stainless steel, basic, or rutile particles that were or were not pretreated with dipalmitoylphosphatidylcholine (2644646). Comparison cultures were treated with titanium-dioxide (13463677) (anatase), chrysotile-asbestos (12001295), trivalent-chromium (16065831) (Cr(III)), or hexavalent-chromium (18540299) (Cr(VI)). After incubation, cell survival was determined by trypan-blue exclusion, and concentrations of lactate dehydrogenase (LDH) and N-acetyl-beta-glucosaminidase were measured. In serum free cultures, Cr(III) and anatase were not toxic but all welding fume particles decreased cell viability: stainless steel particles were the most toxic and rutile particles were the least toxic. Cr(VI) alone was less toxic than the total welding particulate material. LDH was reduced 10 to 15 percent in all groups except anatase, while glucosaminidase release was stimulated only by chrysotile. Addition of serum increased cell survival in all exposure groups. Pretreatment reduced the toxicity of chrysotile asbestos and rutile particles. The authors conclude that the three welding fume particulates are cytotoxic, and that the activity of stainless steel particles is due to the presence of Cr(VI).","Response Of Bovine Alveolar Macrophages In Vitro To Welding Fume Particles AU - White LR Abs: The effects of welding fume particles on bovine alveolar macrophage (AM) survival and enzyme production were studied. AM cultures, with or without bovine serum albumin, were incubated for 17 to 20 hours with stainless steel, basic, or rutile particles that were or were not pretreated with dipalmitoylphosphatidylcholine (2644646). Comparison cultures were treated with titanium-dioxide (13463677) (anatase), chrysotile-asbestos (12001295), trivalent-chromium (16065831) (Cr(III)), or hexavalent-chromium (18540299) (Cr(VI)). After incubation, cell survival was determined by trypan-blue exclusion, and concentrations of lactate dehydrogenase (LDH) and N-acetyl-beta-glucosaminidase were measured. In serum free cultures, Cr(III) and anatase were not toxic but all welding fume particles decreased cell viability: stainless steel particles were the most toxic and rutile particles were the least toxic. Cr(VI) alone was less toxic than the total welding particulate material. LDH was reduced 10 to 15 percent in all groups except anatase, while glucosaminidase release was stimulated only by chrysotile. Addition of serum increased cell survival in all exposure groups. Pretreatment reduced the toxicity of chrysotile asbestos and rutile particles. The authors conclude that the three welding fume particulates are cytotoxic, and that the activity of stainless steel particles is due to the presence of Cr(VI)."
1516114,Marsh and  Mcinerney 1999,Hydrogen availability as an important factor for biological hexavalent chromium reductionymeeting abstract meeting poster bacteria metal bioreduction waste management pollution hydrogen hydrogen availability hexavalent chromium biological reduction sediments aquifers microcosms nutrition bacterial growth electron donors =18540299,Biosis copyright: biol abs. rrm hydrogen availability as an important factor for biological hexavalent chromium reductionymeeting abstract meeting poster bacteria metal bioreduction waste management pollution hydrogen hydrogen availability hexavalent chromium biological reduction sediments aquifers microcosms nutrition bacterial growth electron donors,Hydrogen availability as an important factor for biological hexavalent chromium reductionymeeting abstract meeting poster bacteria metal bioreduction waste management pollution hydrogen hydrogen availability hexavalent chromium biological reduction sediments aquifers microcosms nutrition bacterial growth electron donors =18540299 Abs: Biosis copyright: biol abs. rrm hydrogen availability as an important factor for biological hexavalent chromium reductionymeeting abstract meeting poster bacteria metal bioreduction waste management pollution hydrogen hydrogen availability hexavalent chromium biological reduction sediments aquifers microcosms nutrition bacterial growth electron donors
1516113,Markel et al. 1973,"Health Hazard Evaluation Report HHE-72-106-44, North American Rockwell, Automotive Division, Grenada, Mississippi","Evaluation of hazards from exposure to chromic-acid (7738945) mist in an automotive plant. Medical interviews and examinations show no evidence of permanent injury to the nasal septa or any other effects associated with chronic chromate toxicity. The acceptable ceiling concentration for chromic acid is given as 0.1 milligram per cubic meter. Toxic effects of chromate ion in the hexavalent form are given as skin lesions, called chrome hole, and bronchogenic carcinoma. Recommendations include increasing the hood efficiency over the chrome (7440473) plate tank, exclusion of individuals with skin allergies, chronic eye conditions and respiratory conditions from work in the chrome department, provision of adequate ventilation, safe working conditions, and protective equipment.","Health Hazard Evaluation Report HHE-72-106-44, North American Rockwell, Automotive Division, Grenada, Mississippi Abs: Evaluation of hazards from exposure to chromic-acid (7738945) mist in an automotive plant. Medical interviews and examinations show no evidence of permanent injury to the nasal septa or any other effects associated with chronic chromate toxicity. The acceptable ceiling concentration for chromic acid is given as 0.1 milligram per cubic meter. Toxic effects of chromate ion in the hexavalent form are given as skin lesions, called chrome hole, and bronchogenic carcinoma. Recommendations include increasing the hood efficiency over the chrome (7440473) plate tank, exclusion of individuals with skin allergies, chronic eye conditions and respiratory conditions from work in the chrome department, provision of adequate ventilation, safe working conditions, and protective equipment."
1516112,Mariscal et al. 1995,Evaluation of the Toxicity of Several Heavy Metals by a Fluorescent Bacterial Bioassay,"BIOSIS COPYRIGHT: BIOL ABS. This new bioassay determined the toxicity of chemical compounds dissolved in water by measuring the degree of inhibition of the ultraviolet light-stimulated fluorescence of Escherichia coli in a culture medium in which 4-methylumbelliferyl beta-D-glucuronide was the only carbon source. Inhibition produced by one of five heavy-metal salts (Cd2+, Cr6+, Hg2+, Pb2+ or Zn2+) was the end-point and comparison standard to determine the EC50 and minimum effective concentration (MEC) that produced a decrease of E. coli growth rate, increased doubling time and percentage inhibition and reduced numbers of generations; all these values were derived from the fluorescence signals. Only Cr6+ and Hg2+ at two concentrations (0.25 and 0.5 mg l-1) almost completely inhibited this E. coli strain. All toxicant concentrations tested produced at least partial inhibitions of growth; Cr6+, Hg2+ and Cd2+, in that order, were most toxic, and Pb2+ the least. Zn2+ gave higher EC50 values at 3 h of","Evaluation of the Toxicity of Several Heavy Metals by a Fluorescent Bacterial Bioassay Abs: BIOSIS COPYRIGHT: BIOL ABS. This new bioassay determined the toxicity of chemical compounds dissolved in water by measuring the degree of inhibition of the ultraviolet light-stimulated fluorescence of Escherichia coli in a culture medium in which 4-methylumbelliferyl beta-D-glucuronide was the only carbon source. Inhibition produced by one of five heavy-metal salts (Cd2+, Cr6+, Hg2+, Pb2+ or Zn2+) was the end-point and comparison standard to determine the EC50 and minimum effective concentration (MEC) that produced a decrease of E. coli growth rate, increased doubling time and percentage inhibition and reduced numbers of generations; all these values were derived from the fluorescence signals. Only Cr6+ and Hg2+ at two concentrations (0.25 and 0.5 mg l-1) almost completely inhibited this E. coli strain. All toxicant concentrations tested produced at least partial inhibitions of growth; Cr6+, Hg2+ and Cd2+, in that order, were most toxic, and Pb2+ the least. Zn2+ gave higher EC50 values at 3 h of"
1516111,Mariscal et al. 1994,New toxicity determination method that uses fluorescent assay of Escherichia coli,"BIOSIS COPYRIGHT: BIOL ABS. We describe a new method that uses a fluorogenic bioassay of the beta-glucuronidase conversion of 4-methylumbelliferyl beta-D-glucuronide (MUG) to 4-methylumbelliferone to evaluate the individual toxic effects on Escherichia coli of Al3+, Cr6+, Hg2+ and Li+. This work was designed to examine the effectiveness of this method to measure the effects of five ionic concentrations of either Al3+, Cr6+, Hg2+ or Li+, on the growth of E. coli in a minimal medium that had MUG as the only source of carbon. This method was simple and fast, and its toxicity detection sensitivity was equal to, or greater than, existing bacterial bioassays. The use of the MUG substrate minimized the danger of interference by bacteria other than E. coli. Evaluations of toxicity in samples of public drinking water proved equally sensitive.","New toxicity determination method that uses fluorescent assay of Escherichia coli Abs: BIOSIS COPYRIGHT: BIOL ABS. We describe a new method that uses a fluorogenic bioassay of the beta-glucuronidase conversion of 4-methylumbelliferyl beta-D-glucuronide (MUG) to 4-methylumbelliferone to evaluate the individual toxic effects on Escherichia coli of Al3+, Cr6+, Hg2+ and Li+. This work was designed to examine the effectiveness of this method to measure the effects of five ionic concentrations of either Al3+, Cr6+, Hg2+ or Li+, on the growth of E. coli in a minimal medium that had MUG as the only source of carbon. This method was simple and fast, and its toxicity detection sensitivity was equal to, or greater than, existing bacterial bioassays. The use of the MUG substrate minimized the danger of interference by bacteria other than E. coli. Evaluations of toxicity in samples of public drinking water proved equally sensitive."
1516109,Manzoori et al. 1995,Chromium speciation by a surfactant-coated alumina microcolumn using electrothermal atomic absorption spectrometry,Biosis copyright: biol abs. rrm research article environmental toxin chromiumiii chromiumvi gas furnace-atomic absorption spectrometry analytical method,Chromium speciation by a surfactant-coated alumina microcolumn using electrothermal atomic absorption spectrometry Abs: Biosis copyright: biol abs. rrm research article environmental toxin chromiumiii chromiumvi gas furnace-atomic absorption spectrometry analytical method
1516108,Manzoori and  Shemirani 1995,Determination of chromiumvi and total chromium by inductively coupled plasma atomic emission spectrometry after preconcentration using solvent extraction and back-extraction,Biosis copyright: biol abs. rrm research article environmental toxin water analytical method purification method,Determination of chromiumvi and total chromium by inductively coupled plasma atomic emission spectrometry after preconcentration using solvent extraction and back-extraction Abs: Biosis copyright: biol abs. rrm research article environmental toxin water analytical method purification method
1516106,Manju and  Anirudhan 1997,Use of coconut fibre pith-based pseudo-activated carbon for chromium (VI) removal,"BIOSIS COPYRIGHT: BIOL ABS. The ability of coconut fibre pith carbon to remove Cr(VI) from aqueous solution by adsorption was studied. The extent of removal was found to be dependent on sorbent dose, initial concentration, pH and temperature. The adsorption follows a second order kinetics. An empirical relationship has been suggested to predict the percentage Cr(VI) removal at any time for known values of sorbent dose and initial sorbate concentration under observed test conditions. Studies on the diverse ions reveal that the sorption of Cr(VI) is practically unaffected by the presence of diverse ions. The adsorption process is exothermic with a maximum adsorption of 99.2 percent at 30êC for an initial concentration of 50 mgL-1 at pH 2.0. Thermodynamic parameters were evaluated. Desorption studies revealed that the spent adsorbent can be regenerated and reused by alkali treatment.","Use of coconut fibre pith-based pseudo-activated carbon for chromium (VI) removal Abs: BIOSIS COPYRIGHT: BIOL ABS. The ability of coconut fibre pith carbon to remove Cr(VI) from aqueous solution by adsorption was studied. The extent of removal was found to be dependent on sorbent dose, initial concentration, pH and temperature. The adsorption follows a second order kinetics. An empirical relationship has been suggested to predict the percentage Cr(VI) removal at any time for known values of sorbent dose and initial sorbate concentration under observed test conditions. Studies on the diverse ions reveal that the sorption of Cr(VI) is practically unaffected by the presence of diverse ions. The adsorption process is exothermic with a maximum adsorption of 99.2 percent at 30êC for an initial concentration of 50 mgL-1 at pH 2.0. Thermodynamic parameters were evaluated. Desorption studies revealed that the spent adsorbent can be regenerated and reused by alkali treatment."
1516104,Makos et al. 1994,Removal of chromium vi from acidic wastes using constructed wetlands,Biosis copyright: biol abs. rrm meeting abstract meeting poster pollution prevention analytical method,Removal of chromium vi from acidic wastes using constructed wetlands Abs: Biosis copyright: biol abs. rrm meeting abstract meeting poster pollution prevention analytical method
1516103,Makos and  Hrncir 1995,Chemistry of Cr(VI) in a constructed wetland,BIOSIS COPYRIGHT: BIOL ABS. The feasibility of the use of constructed wetlands to treat acidic wastes containing hexavalent chromium is successfully demonstrated on a laboratory scale. The chemistry of Cr(VI) in this system has been determined. Cr(VI) removal is highly dependent upon the organic content of the wetland matrix.,Chemistry of Cr(VI) in a constructed wetland Abs: BIOSIS COPYRIGHT: BIOL ABS. The feasibility of the use of constructed wetlands to treat acidic wastes containing hexavalent chromium is successfully demonstrated on a laboratory scale. The chemistry of Cr(VI) in this system has been determined. Cr(VI) removal is highly dependent upon the organic content of the wetland matrix.
1516102,Makdisi 1991,"Tannery wastes definition, risk assessment and cleanup options, Berkeley, California","BIOSIS COPYRIGHT: BIOL ABS. United States tanneries generate up to 100,000 (wet) tons of hair-burn and chrome sludges and contaminated soils. A facility closure investigation at a tannery in Berkeley, California showed sludges containing concentrations of Cr in the range of 1,000 to 40,000 mg/kg on a dry weight basis. California Code of Regulations defines total chromium above a concentration of 2,500 mg/kg in soil or sludge as hazardous waste. Chromium desorption from the soil matrix and Cr solubility are low. Migration of chromium in the soil water occurs either as a soluble Cr (VI) species, HCrO4- and CrO42- or as Cr (III) and Cr(VI) in soluble complexes with organic or inorganic substances. Investigations at the Berkeley tannery indicate these tannery sludges exhibit low mobility and have Cr(III) to Cr(VI) ratio were 200. A risk assessment was completed to assess the possible effects on publich health, but they were determined to be insignificant. Cleanup options evaluated were offsite disposal","Tannery wastes definition, risk assessment and cleanup options, Berkeley, California Abs: BIOSIS COPYRIGHT: BIOL ABS. United States tanneries generate up to 100,000 (wet) tons of hair-burn and chrome sludges and contaminated soils. A facility closure investigation at a tannery in Berkeley, California showed sludges containing concentrations of Cr in the range of 1,000 to 40,000 mg/kg on a dry weight basis. California Code of Regulations defines total chromium above a concentration of 2,500 mg/kg in soil or sludge as hazardous waste. Chromium desorption from the soil matrix and Cr solubility are low. Migration of chromium in the soil water occurs either as a soluble Cr (VI) species, HCrO4- and CrO42- or as Cr (III) and Cr(VI) in soluble complexes with organic or inorganic substances. Investigations at the Berkeley tannery indicate these tannery sludges exhibit low mobility and have Cr(III) to Cr(VI) ratio were 200. A risk assessment was completed to assess the possible effects on publich health, but they were determined to be insignificant. Cleanup options evaluated were offsite disposal"
1516100,Mahon and  Godbey 1983,"In-Depth Survey Report, Control Technology For The Ceramics Industry, Didier Taylor Refractories Corporation, Newton, Ohio, Report No. CT-110-12b","An in depth control technology survey was conducted at the Didier Taylor Refractories Corporation (SIC-3255), Newtown, Ohio in July 1982. Area and breathing zone samples were analyzed for free silica (14808607), respirable and total dust, hexavalent-chromium (18540299) and elemental chromium (7440473). The effectiveness of the engineering controls was evaluated. Work practices were observed. The facility used local and general exhaust ventilation, local exhaust duct work, filter dust collectors and blowers, and integral exhaust hoods on the baggers to control exposures. Air concentrations of free silica, respirable and total dust, and hexavalent and elemental chromium were below the relevant federal standards; chromium concentrations were below the detection limit. Good work practices were achieved by a program that combined housekeeping, incentive awards, and a labor/management committee. NIOSH approved respirators and other personal protective equipment were available and use was mandatory. Recommendations include monitoring the airflow of recirculated air in the local ventilation system for contamination and establishing a program to ensure proper selection, fitting, and maintenance of respirators.","In-Depth Survey Report, Control Technology For The Ceramics Industry, Didier Taylor Refractories Corporation, Newton, Ohio, Report No. CT-110-12b Abs: An in depth control technology survey was conducted at the Didier Taylor Refractories Corporation (SIC-3255), Newtown, Ohio in July 1982. Area and breathing zone samples were analyzed for free silica (14808607), respirable and total dust, hexavalent-chromium (18540299) and elemental chromium (7440473). The effectiveness of the engineering controls was evaluated. Work practices were observed. The facility used local and general exhaust ventilation, local exhaust duct work, filter dust collectors and blowers, and integral exhaust hoods on the baggers to control exposures. Air concentrations of free silica, respirable and total dust, and hexavalent and elemental chromium were below the relevant federal standards; chromium concentrations were below the detection limit. Good work practices were achieved by a program that combined housekeeping, incentive awards, and a labor/management committee. NIOSH approved respirators and other personal protective equipment were available and use was mandatory. Recommendations include monitoring the airflow of recirculated air in the local ventilation system for contamination and establishing a program to ensure proper selection, fitting, and maintenance of respirators."
1516095,Macchi et al. 1991,A bench study on chromium recovery from tannery sludge,"BIOSIS COPYRIGHT: BIOL ABS. A process study on separation and recovery of Cr(III) from tannery sludge is presented. The main steps of the process include Cr(III) extraction with sulphuric acid solution at pH 1, Cr(III) oxidation to Cr(VI) with H2O2, Cr(VI) separation from other cations and its subsequent reduction to Cr(III). The experimental conditions for each of the above steps are optimized on a bench scale. The overall Cr(III) recovery yield from sludges, controlled by the extraction and oxidative phases, amounts to 80%. Cr(II) recovery from segregated exhausted tannery baths, characterized by low concentration of major cations, is quantitative. The (Fe + Mg)r molar ratio strongly influences the H2O2/Cr ratio required to obtain near quantitative Cr(III) oxidation. At present, the running costs may be estimated to be about double that of disposing of sludges in controlled landfills. The tendency to eliminate Fe(II) in tannery wastewaters treatment would significantly reduce the process cost an","A bench study on chromium recovery from tannery sludge Abs: BIOSIS COPYRIGHT: BIOL ABS. A process study on separation and recovery of Cr(III) from tannery sludge is presented. The main steps of the process include Cr(III) extraction with sulphuric acid solution at pH 1, Cr(III) oxidation to Cr(VI) with H2O2, Cr(VI) separation from other cations and its subsequent reduction to Cr(III). The experimental conditions for each of the above steps are optimized on a bench scale. The overall Cr(III) recovery yield from sludges, controlled by the extraction and oxidative phases, amounts to 80%. Cr(II) recovery from segregated exhausted tannery baths, characterized by low concentration of major cations, is quantitative. The (Fe + Mg)r molar ratio strongly influences the H2O2/Cr ratio required to obtain near quantitative Cr(III) oxidation. At present, the running costs may be estimated to be about double that of disposing of sludges in controlled landfills. The tendency to eliminate Fe(II) in tannery wastewaters treatment would significantly reduce the process cost an"
1516092,Ma and  Crawford-Brown 1997,Comparison of systems and single-medium approaches in environmental risk-based decision making: A case study of a sludge management problem,"BIOSIS COPYRIGHT: BIOL ABS. The traditional single-medium approach to environmental management mitigates problems in one environmental medium at a time without considering interactions between different media. The management strategies selected from the single-medium approach may, therefore, simply shift problems between media. Alternatively, a systems approach advocates focusing on the environmental system as a source of risk, and selecting risk management strategies based on minimization of the composite risk from all pa imedia risk analysis and an optimization framework to develop a methodology for comparing the merits of the two approaches. We then apply the methodology to a sludge management decision problem and demonstrate that there are many cases in which the systems approach leads to the selection of optimal management strategies that differ from those using a single-medium approach.","Comparison of systems and single-medium approaches in environmental risk-based decision making: A case study of a sludge management problem Abs: BIOSIS COPYRIGHT: BIOL ABS. The traditional single-medium approach to environmental management mitigates problems in one environmental medium at a time without considering interactions between different media. The management strategies selected from the single-medium approach may, therefore, simply shift problems between media. Alternatively, a systems approach advocates focusing on the environmental system as a source of risk, and selecting risk management strategies based on minimization of the composite risk from all pa imedia risk analysis and an optimization framework to develop a methodology for comparing the merits of the two approaches. We then apply the methodology to a sludge management decision problem and demonstrate that there are many cases in which the systems approach leads to the selection of optimal management strategies that differ from those using a single-medium approach."
1516091,Lytle et al. 1996,Phyto-conversion of crvi to criii by water hyacinth a case for phytoremediation,Biosis copyright: biol abs. rrm meeting abstract water hyacinth ecology pollution phytoremediation chromium pollutant chromium metabolism plant non-toxic form toxic form,Phyto-conversion of crvi to criii by water hyacinth a case for phytoremediation Abs: Biosis copyright: biol abs. rrm meeting abstract water hyacinth ecology pollution phytoremediation chromium pollutant chromium metabolism plant non-toxic form toxic form
1516090,Lytle et al. 1998,Reduction of Cr(VI) to Cr(III) by wetland plants: Potential for in situ heavy metal detoxification,"BIOSIS COPYRIGHT: BIOL ABS. Reduction of heavy metals in situ by plants may be a useful detoxification mechanism for phytoremediation. Using X-ray spectroscopy, we show that Eichhornia crassipes (water hyacinth), supplied with Cr(VI) in nutrient culture, accumulated nontoxic Cr(III) in root and shoot tissues. The reduction of Cr(VI) to Cr(III) appeared to occur in the fine lateral roots. The Cr(III) was subsequently translocated to leaf tissues. Extended X-ray absorption fine structure of Cr in leaf and petiole differed when compared to Cr in roots. In roots, Cr(III) was hydrated by water, but in petiole and more so in leaf, a portion of the Cr(III) may be bound to oxalate ligands. This suggests that E. crassipes detoxified Cr(VI) upon root uptake and transported a portion of the detoxified Cr to leaf tissues. Cr-rich crystalline structures were observed on the leaf surface. The chemical species of Cr in other plants, collected from wetlands that contained Cr(VI)-contaminated wastewater, was also","Reduction of Cr(VI) to Cr(III) by wetland plants: Potential for in situ heavy metal detoxification Abs: BIOSIS COPYRIGHT: BIOL ABS. Reduction of heavy metals in situ by plants may be a useful detoxification mechanism for phytoremediation. Using X-ray spectroscopy, we show that Eichhornia crassipes (water hyacinth), supplied with Cr(VI) in nutrient culture, accumulated nontoxic Cr(III) in root and shoot tissues. The reduction of Cr(VI) to Cr(III) appeared to occur in the fine lateral roots. The Cr(III) was subsequently translocated to leaf tissues. Extended X-ray absorption fine structure of Cr in leaf and petiole differed when compared to Cr in roots. In roots, Cr(III) was hydrated by water, but in petiole and more so in leaf, a portion of the Cr(III) may be bound to oxalate ligands. This suggests that E. crassipes detoxified Cr(VI) upon root uptake and transported a portion of the detoxified Cr to leaf tissues. Cr-rich crystalline structures were observed on the leaf surface. The chemical species of Cr in other plants, collected from wetlands that contained Cr(VI)-contaminated wastewater, was also"
1516089,Luli et al. 1982,Isolation of hexavalent chromium resistant bacteria from river sediments,Heep copyright: biol abs. abstract contamination industrial waste,Isolation of hexavalent chromium resistant bacteria from river sediments Abs: Heep copyright: biol abs. abstract contamination industrial waste
1516087,Lowry et al. 1982,Measurement of corrosion rate and ep toxicity hexavalent chromium for rcra samples by voltammetric techniques,Heep copyright: biol abs. abstract metal pollution differential pulse polarography,Measurement of corrosion rate and ep toxicity hexavalent chromium for rcra samples by voltammetric techniques Abs: Heep copyright: biol abs. abstract metal pollution differential pulse polarography
1516086,Low et al. 1997,Biosorption of hexavalent chromium from aqueous solution by Hydrilla verticillata,"BIOSIS COPYRIGHT: BIOL ABS. The ability of non-living biomass of an aquatic plant, Hydrilla verticillata, to remove Cr(VI) from aqueous solution was studied at different initial concentrations, temperatures, pH, sorbent dosages, contact time and in the presence of competing anions. The uptake was pH dependent and maximum sorption occurred at pH 2. The Langmuir isotherm model was used to describe the sorption of Cr(VI) on Hydrilla and the maximum uptake for Cr(VI)-Hydrilla system was 30 mg/gm. Thermodynamic studies showed that the sorption process was exothermic. The interference effect of other anions on the Hydrilla was also studied. Results indicate the following order of suppression of Cr(VI) by the various anions: SO42- > HPO42- > NO3- > Cl-.","Biosorption of hexavalent chromium from aqueous solution by Hydrilla verticillata Abs: BIOSIS COPYRIGHT: BIOL ABS. The ability of non-living biomass of an aquatic plant, Hydrilla verticillata, to remove Cr(VI) from aqueous solution was studied at different initial concentrations, temperatures, pH, sorbent dosages, contact time and in the presence of competing anions. The uptake was pH dependent and maximum sorption occurred at pH 2. The Langmuir isotherm model was used to describe the sorption of Cr(VI) on Hydrilla and the maximum uptake for Cr(VI)-Hydrilla system was 30 mg/gm. Thermodynamic studies showed that the sorption process was exothermic. The interference effect of other anions on the Hydrilla was also studied. Results indicate the following order of suppression of Cr(VI) by the various anions: SO42- > HPO42- > NO3- > Cl-."
1516085,Low et al. 1999,Column study on the sorption of Cr(VI) using quaternized rice hulls,"BIOSIS COPYRIGHT: BIOL ABS. The potential of quaternized rice hulls in removing Cr(VI) from synthetic solution, chrome electroplating waste and wood preservative waste was investigated in column experiments. Increase in column bed depth resulted in a longer service time at Cto = 0.5 breakthrough. The presence of SO42-, which is commonly present in the wastes, interfered with the sorption process and resulted in earlier breakthrough. The sorption process was flow-rate independent within the scope of this study. In the regeneration study, Cr(VI) could be recovered almost quantitatively by eluting with a 0.5 M NaOH solution and the column could be used repeatedly for at least five cycles.","Column study on the sorption of Cr(VI) using quaternized rice hulls Abs: BIOSIS COPYRIGHT: BIOL ABS. The potential of quaternized rice hulls in removing Cr(VI) from synthetic solution, chrome electroplating waste and wood preservative waste was investigated in column experiments. Increase in column bed depth resulted in a longer service time at Cto = 0.5 breakthrough. The presence of SO42-, which is commonly present in the wastes, interfered with the sorption process and resulted in earlier breakthrough. The sorption process was flow-rate independent within the scope of this study. In the regeneration study, Cr(VI) could be recovered almost quantitatively by eluting with a 0.5 M NaOH solution and the column could be used repeatedly for at least five cycles."
1516084,Lovley et al. 1993,Cytochrome c-3 is a heavy-metal reductase,Biosis copyright: biol abs. rrm abstract desulfovibrio-vulgaris iron-iii uranium-vi chromium-vi gold-iii contaminated water detoxification,Cytochrome c-3 is a heavy-metal reductase Abs: Biosis copyright: biol abs. rrm abstract desulfovibrio-vulgaris iron-iii uranium-vi chromium-vi gold-iii contaminated water detoxification
1516083,Lovley and  Phillips 1994,Reduction of chromate by Desulfovibrio vulgaris and its C3 cytochrome,BIOSIS COPYRIGHT: BIOL ABS. Washed cell suspensions of Desulfovibrio vulgaris rapidly reduced Cr(VI) to Cr(III) with H2 as the electron donor. The c3 cytochrome from this organism functioned as a Cr(VI) reductase. D. vulgaris may have advantages over previously described Cr(VI) reducers for the bioremediation of Cr(VI)-contaminated waters.,Reduction of chromate by Desulfovibrio vulgaris and its C3 cytochrome Abs: BIOSIS COPYRIGHT: BIOL ABS. Washed cell suspensions of Desulfovibrio vulgaris rapidly reduced Cr(VI) to Cr(III) with H2 as the electron donor. The c3 cytochrome from this organism functioned as a Cr(VI) reductase. D. vulgaris may have advantages over previously described Cr(VI) reducers for the bioremediation of Cr(VI)-contaminated waters.
1516082,Lovley 1993,Anaerobes into heavy metal dissimilatory metal reduction in anoxic environments,Biosis copyright: biol abs. rrm review bacteria microbial metabolism contaminant degradation radioactive metal model,Anaerobes into heavy metal dissimilatory metal reduction in anoxic environments Abs: Biosis copyright: biol abs. rrm review bacteria microbial metabolism contaminant degradation radioactive metal model
1516081,Losi et al. 1994,Bioremediation of chromate-contaminated groundwater by reduction and precipitation in surface soils,"BIOSIS COPYRIGHT: BIOL ABS. A cost-effective method is needed for removing chromate from cooling water blowdown, wastewater effluent, and contaminated groundwater. Experiments were conducted to determine the effectiveness of treating Cr-contaminated water by using the water for irrigation, and that reduction of Cr(VI) to Cr(III) would occur in a soil amended with organic matter and irrigated to promote low oxidation/reduction status. The Cr(III) would then precipitate as oxides and hydroxides, and be immobilized and rendered plant unavailable. Samples of a field soil (mixed, thermic Typic Torripsamments) overlying a contaminated groundwater site were placed in pots and irrigated for 20 wk with water containing 1000 mug L-1 Cr(VI). Treatments included plants (alfalfa; Medicago sativa L.) vs. no plants, each at three organic matter loadings - 0, 12, and 50 Mg ha-1 dried cattle manure (0, 5.5, and 21.8 g manure kg-1 soil). The drainage waters were collected weekly and analyzed for total Cr, Cr(VI)","Bioremediation of chromate-contaminated groundwater by reduction and precipitation in surface soils Abs: BIOSIS COPYRIGHT: BIOL ABS. A cost-effective method is needed for removing chromate from cooling water blowdown, wastewater effluent, and contaminated groundwater. Experiments were conducted to determine the effectiveness of treating Cr-contaminated water by using the water for irrigation, and that reduction of Cr(VI) to Cr(III) would occur in a soil amended with organic matter and irrigated to promote low oxidation/reduction status. The Cr(III) would then precipitate as oxides and hydroxides, and be immobilized and rendered plant unavailable. Samples of a field soil (mixed, thermic Typic Torripsamments) overlying a contaminated groundwater site were placed in pots and irrigated for 20 wk with water containing 1000 mug L-1 Cr(VI). Treatments included plants (alfalfa; Medicago sativa L.) vs. no plants, each at three organic matter loadings - 0, 12, and 50 Mg ha-1 dried cattle manure (0, 5.5, and 21.8 g manure kg-1 soil). The drainage waters were collected weekly and analyzed for total Cr, Cr(VI)"
1516079,Locatelli and  Fagioli 1986,Determination of chromium(VI) in dialysis fluids by alternating current and differential pulse voltammetry,"BIOSIS COPYRIGHT: BIOL ABS. Alternating current (ACV) and differential pulse voltammetry (DPV) are employed for the determination of Cr(VI) in dialysis fluids, using 0.1 mol/l dibasic ammonium citrate as supporting electrolyte (pH 5.9). A three-electrode cell was used: The working electrode was a long-lasting sessile-drop mercury electrode (LLSDME) with a drop time of 240 to 300 s. Precision, expressed as relative standard deviation (sr%), and accuracy, expressed as relative recovery (R%) are also reported.","Determination of chromium(VI) in dialysis fluids by alternating current and differential pulse voltammetry Abs: BIOSIS COPYRIGHT: BIOL ABS. Alternating current (ACV) and differential pulse voltammetry (DPV) are employed for the determination of Cr(VI) in dialysis fluids, using 0.1 mol/l dibasic ammonium citrate as supporting electrolyte (pH 5.9). A three-electrode cell was used: The working electrode was a long-lasting sessile-drop mercury electrode (LLSDME) with a drop time of 240 to 300 s. Precision, expressed as relative standard deviation (sr%), and accuracy, expressed as relative recovery (R%) are also reported."
1516078,Lloyd et al. 1997,Generation of putative intrastrand cross-links and strand breaks in DNA by transition metal ion-mediated oxygen radical attack,"BIOSIS COPYRIGHT: BIOL ABS. Generation of putative intrastrand cross-links and strand breaks was investigated in salmon sperm DNA exposed to Fenton-type oxygen radical-generating systems. 32P-Postlabelling analysis of DNA treated with hydrogen peroxide and either copper(II), chromium(VI), cobalt(II), iron(II), nickel(II), or vanadium(III) resulted in the detection of between four and eight radioactive TLC spots that are probably hydroxyl radical-mediated oxidative DNA lesions. The copper Fenton system generated the highest total yield of these DNA lesions (75.6 per 108 nucleotides), followed by cobalt (47.5), nickel (26.2), chromium (25.1), iron (21.7), and vanadium (17.1). Two spots, common to all these Fenton systems, were the major oxidation products in each case. Similar Fenton-type treatment of the purine dinucleotides dApdG and dApdA resulted in products that were chromatographically identical on anion-exchange TLC and on reverse-phase HPLC to the two major products generated in DNA. These r","Generation of putative intrastrand cross-links and strand breaks in DNA by transition metal ion-mediated oxygen radical attack Abs: BIOSIS COPYRIGHT: BIOL ABS. Generation of putative intrastrand cross-links and strand breaks was investigated in salmon sperm DNA exposed to Fenton-type oxygen radical-generating systems. 32P-Postlabelling analysis of DNA treated with hydrogen peroxide and either copper(II), chromium(VI), cobalt(II), iron(II), nickel(II), or vanadium(III) resulted in the detection of between four and eight radioactive TLC spots that are probably hydroxyl radical-mediated oxidative DNA lesions. The copper Fenton system generated the highest total yield of these DNA lesions (75.6 per 108 nucleotides), followed by cobalt (47.5), nickel (26.2), chromium (25.1), iron (21.7), and vanadium (17.1). Two spots, common to all these Fenton systems, were the major oxidation products in each case. Similar Fenton-type treatment of the purine dinucleotides dApdG and dApdA resulted in products that were chromatographically identical on anion-exchange TLC and on reverse-phase HPLC to the two major products generated in DNA. These r"
1516076,Liu et al. 1988,The use of isolated rat hepatocyte in prescreening of hepatotoxicants: Observation on toxic effects of 14 compounds,"BIOSIS COPYRIGHT: BIOL ABS. Fourteen compounds, differing in structure, mechanism of action, and primary target organs, were tested for cytotoxic responses in isolated hepatocyte suspensions prepared by a nonperfusion method from male Sprague-Dawley rats. The trypan blue exclusion test, measurement of enzyme activities in supernatants, and enzyme histochemistry were taken as indexes of cytotoxicity. All 14 compounds inhibited enzyme activities in hepatocytes. However, the activities of GOT and LDH in supernatants increased after exposure to the three haloalkanes, but decreased after exposure to the other chemicals (Na2CrO4, etc.). The number of dyed cells increased after exposure to six haloalkanes and the order of their relative toxicities in vitro was roughly in concordance with that of their in vivo hepatotoxicities. These results indicate that isolated hepatocytes are useful for prescreening of potential hepatotoxicants; the so-called ""enzyme leakage"" should be replaced by ""enzyme in supernatan","The use of isolated rat hepatocyte in prescreening of hepatotoxicants: Observation on toxic effects of 14 compounds Abs: BIOSIS COPYRIGHT: BIOL ABS. Fourteen compounds, differing in structure, mechanism of action, and primary target organs, were tested for cytotoxic responses in isolated hepatocyte suspensions prepared by a nonperfusion method from male Sprague-Dawley rats. The trypan blue exclusion test, measurement of enzyme activities in supernatants, and enzyme histochemistry were taken as indexes of cytotoxicity. All 14 compounds inhibited enzyme activities in hepatocytes. However, the activities of GOT and LDH in supernatants increased after exposure to the three haloalkanes, but decreased after exposure to the other chemicals (Na2CrO4, etc.). The number of dyed cells increased after exposure to six haloalkanes and the order of their relative toxicities in vitro was roughly in concordance with that of their in vivo hepatotoxicities. These results indicate that isolated hepatocytes are useful for prescreening of potential hepatotoxicants; the so-called ""enzyme leakage"" should be replaced by ""enzyme in supernatan"
1516072,Lintott et al. 1995,Comparison of selected test methods for screening soil contaminants,Biosis copyright: biol abs. rrm meeting abstract pollution soil toxicity contamination analytical method,Comparison of selected test methods for screening soil contaminants Abs: Biosis copyright: biol abs. rrm meeting abstract pollution soil toxicity contamination analytical method
1516068,Lindberg et al. 1985,Extent And Conditions Of Exposure In The Swedish Chrome Plating Industry,"The extent and conditions of exposure in the Swedish chrome plating industry were investigated. At 13 factories with 84 workers, air monitoring was done for chromium (7440473) and other metals using personal samplers and stationary sampling devices. The percentage of respirable particles was measured at one hard plating factory. During a single work day at 16 chrome plating baths, hexavalent chromium exceeded the sanitary limit of 20 micrograms/cubic meter (microg/m3). The highest value was 46microg/m3. At four baths, exposure to chromium(VI) was lower than 1microg/m3 and at the remaining baths, chromium(VI) concentrations ranged from 1.5 to 10microg/m3. Polishing resulted in the lowest exposure to hexavalent chromium, but the highest overall exposures due to metallic chromium in the air. Over 16 or 19 days examined to determine concentration fluctuations over a work week, exposure concentrations ranged well within 50 percent deviations from the week median. In one hard chrome plating factory where size and distribution of particles was monitored at 2 meters above the floor in the middle of the factory, the diameter of the particles varied between 0.1 and 3.4 micrometers. All particles contained in the dust were thus respirable. Just above the chromium bath, the respirable portion comprised 99.9 percent of the particle content and was estimated to be 40 percent of the total particle volume. Where decorative chrome plating was done, exposure was much lower, approximately 0.1 to 0.3microg/m3. But concentrations were substantially higher at one factory which lacked a local exhaust device. Median nickel (7440020) concentrations were 6microg/m3; zinc (7440666), 3.6microg/m3; copper (7440508), 12microg/m3; tin (7440315), 9.7microg/m3; and cadmium (7440439), 0.5microg/m3. The authors conclude that both effective slot exhausts and good, well balanced general ventilation are important factors in reducing chromium exposure.","Extent And Conditions Of Exposure In The Swedish Chrome Plating Industry Abs: The extent and conditions of exposure in the Swedish chrome plating industry were investigated. At 13 factories with 84 workers, air monitoring was done for chromium (7440473) and other metals using personal samplers and stationary sampling devices. The percentage of respirable particles was measured at one hard plating factory. During a single work day at 16 chrome plating baths, hexavalent chromium exceeded the sanitary limit of 20 micrograms/cubic meter (microg/m3). The highest value was 46microg/m3. At four baths, exposure to chromium(VI) was lower than 1microg/m3 and at the remaining baths, chromium(VI) concentrations ranged from 1.5 to 10microg/m3. Polishing resulted in the lowest exposure to hexavalent chromium, but the highest overall exposures due to metallic chromium in the air. Over 16 or 19 days examined to determine concentration fluctuations over a work week, exposure concentrations ranged well within 50 percent deviations from the week median. In one hard chrome plating factory where size and distribution of particles was monitored at 2 meters above the floor in the middle of the factory, the diameter of the particles varied between 0.1 and 3.4 micrometers. All particles contained in the dust were thus respirable. Just above the chromium bath, the respirable portion comprised 99.9 percent of the particle content and was estimated to be 40 percent of the total particle volume. Where decorative chrome plating was done, exposure was much lower, approximately 0.1 to 0.3microg/m3. But concentrations were substantially higher at one factory which lacked a local exhaust device. Median nickel (7440020) concentrations were 6microg/m3; zinc (7440666), 3.6microg/m3; copper (7440508), 12microg/m3; tin (7440315), 9.7microg/m3; and cadmium (7440439), 0.5microg/m3. The authors conclude that both effective slot exhausts and good, well balanced general ventilation are important factors in reducing chromium exposure."
1516067,Lin et al. 1992,Treatment strategy for chromium-vi-bearing wastes,Biosis copyright: biol abs. rrm wastewater treatment water pollution control heavy metals reducing agents alkali leachability,Treatment strategy for chromium-vi-bearing wastes Abs: Biosis copyright: biol abs. rrm wastewater treatment water pollution control heavy metals reducing agents alkali leachability
1516063,Li et al. 1998,"Changes of surface water pollution of Suzhou region: A case study in Taicang County, China","BIOSIS COPYRIGHT: BIOL ABS. Environmental pollution is a by-product of industrialization when economy of a region is developing. China also suffers from such a problem, especially in the southern part like Suzhou region in Jiangsu Province. In this paper, data covering situations of surface water pollution and social and economic development showed that the surface water pollution in Taicang County, a typical economic zone of Suzhou region, is significantly correlated to the economic growth of this region.","Changes of surface water pollution of Suzhou region: A case study in Taicang County, China Abs: BIOSIS COPYRIGHT: BIOL ABS. Environmental pollution is a by-product of industrialization when economy of a region is developing. China also suffers from such a problem, especially in the southern part like Suzhou region in Jiangsu Province. In this paper, data covering situations of surface water pollution and social and economic development showed that the surface water pollution in Taicang County, a typical economic zone of Suzhou region, is significantly correlated to the economic growth of this region."
1516061,Lewis et al. 1981,Determining the Role of Pulmonary Fibrosis in the Etiology of Lung Cancer,"The work accomplished during the first phase of a joint project between NIOSH and the National Cancer Institutes was reported; the project was to develop an experimental model to test the hypothesis that pulmonary fibrosis presents a cocarcinogenic effect in the etiology of pulmonary carcinoma. Future work will include an animal study in which simultaneous exposure was given to the fibrogenic agent and a carcinogen. During this first phase the type and extent of pulmonary fibrotic response occurring in male Syrian-golden-hamsters receiving multiple intratracheal instillations given once weekly for 15 weeks of crystalline quartz (14808607), fibrous glass, hydrated alumina (21645512), or a 1:1 mix of ferric-oxide (1309371) and crystalline quartz was determined. There were 18 treatment groups of four animals each receiving treatment at four dose levels; two groups served as controls. An overall 58 percent mortality rate was noted by the end of week 82. Amyloidosis was the cause or a contributing cause in the deaths of many of the hamsters. Increased mortality was noted for animals receiving the two higher doses of quartz and quartz plus ferric-oxide. Animals receiving all dose levels of alumina and fibrous glass had mortalities similar to control animals. Decreased body weight was noted at the highest treatment dose of each treatment group.","Determining the Role of Pulmonary Fibrosis in the Etiology of Lung Cancer Abs: The work accomplished during the first phase of a joint project between NIOSH and the National Cancer Institutes was reported; the project was to develop an experimental model to test the hypothesis that pulmonary fibrosis presents a cocarcinogenic effect in the etiology of pulmonary carcinoma. Future work will include an animal study in which simultaneous exposure was given to the fibrogenic agent and a carcinogen. During this first phase the type and extent of pulmonary fibrotic response occurring in male Syrian-golden-hamsters receiving multiple intratracheal instillations given once weekly for 15 weeks of crystalline quartz (14808607), fibrous glass, hydrated alumina (21645512), or a 1:1 mix of ferric-oxide (1309371) and crystalline quartz was determined. There were 18 treatment groups of four animals each receiving treatment at four dose levels; two groups served as controls. An overall 58 percent mortality rate was noted by the end of week 82. Amyloidosis was the cause or a contributing cause in the deaths of many of the hamsters. Increased mortality was noted for animals receiving the two higher doses of quartz and quartz plus ferric-oxide. Animals receiving all dose levels of alumina and fibrous glass had mortalities similar to control animals. Decreased body weight was noted at the highest treatment dose of each treatment group."
1516059,Lewandowski 1987,Behavior of biological reactors in the presence of toxic compounds,Biosis copyright: biol abs. rrm chromium model wastewater treatment,Behavior of biological reactors in the presence of toxic compounds Abs: Biosis copyright: biol abs. rrm chromium model wastewater treatment
1516058,Lewandowski 1986,Biological reactor resistance to inhibition,Biosis copyright: biol abs. rrm chromium denitrification wastewater treatment,Biological reactor resistance to inhibition Abs: Biosis copyright: biol abs. rrm chromium denitrification wastewater treatment
1516056,Levi et al. 1990,The effect of chromium-vi on maize roots ii. cell cycle and nuclear structure,Biosis copyright: biol abs. rrm abstract,The effect of chromium-vi on maize roots ii. cell cycle and nuclear structure Abs: Biosis copyright: biol abs. rrm abstract
1516055,Leow and  Goh 1999,Contact allergy in Singapore,"BIOSIS COPYRIGHT: BIOL ABS. Contact allergy, viz. allergic contact dermatitis, photo-allergic contact dermatitis and contact urticaria, is a well-studied sub-specialty of dermatology in Singapore. Over the years, numerous studies and anecdotal reports on the subject have been published in both international and local refereed journals. This article reviews the epidemiological data on patch testing and photo-patch testing in Singapore. It also summarizes published clinical reports on important contact allergens that are found in both non-occupational and occupational setting.","Contact allergy in Singapore Abs: BIOSIS COPYRIGHT: BIOL ABS. Contact allergy, viz. allergic contact dermatitis, photo-allergic contact dermatitis and contact urticaria, is a well-studied sub-specialty of dermatology in Singapore. Over the years, numerous studies and anecdotal reports on the subject have been published in both international and local refereed journals. This article reviews the epidemiological data on patch testing and photo-patch testing in Singapore. It also summarizes published clinical reports on important contact allergens that are found in both non-occupational and occupational setting."
1516052,Lee and  Kim 1990,A study of sedimentary environment in the estuary of Nakdong River (South Korea): Sedimentation processes and heavy metal distributions,"BIOSIS COPYRIGHT: BIOL ABS. The sedimentation processes and heavy metal distributions at the Nakdong estuary were investigated during October 1987 and September 1988. The depositional sedimentary environment of the studied area was estuarine environments and was divided into three provinces depending on its textural parameters such as barrier, tidal flat, and water passes. The relationship between the textural parameters showed that the barrier was under strong wave action, that the tidal flat was under relatively weak wind-driven currents, and that the water passes were under strong and continuous tidal currents. Each environment was resulted from different transport mechanism. The sand barrier sediments were transported by all three populations including suspension, saltation, and bed load. And water pass-deposited sediments were by the bed load with some suspension population. In water mass over the studied area, the concentrations of heavy metals including Cu, Cd, Cr+6, Pb and Zn were recorded","A study of sedimentary environment in the estuary of Nakdong River (South Korea): Sedimentation processes and heavy metal distributions Abs: BIOSIS COPYRIGHT: BIOL ABS. The sedimentation processes and heavy metal distributions at the Nakdong estuary were investigated during October 1987 and September 1988. The depositional sedimentary environment of the studied area was estuarine environments and was divided into three provinces depending on its textural parameters such as barrier, tidal flat, and water passes. The relationship between the textural parameters showed that the barrier was under strong wave action, that the tidal flat was under relatively weak wind-driven currents, and that the water passes were under strong and continuous tidal currents. Each environment was resulted from different transport mechanism. The sand barrier sediments were transported by all three populations including suspension, saltation, and bed load. And water pass-deposited sediments were by the bed load with some suspension population. In water mass over the studied area, the concentrations of heavy metals including Cu, Cd, Cr+6, Pb and Zn were recorded"
1516050,Lee and  Lustigman 1995,The effect of thallium and hexavalent chromium on the growth of anacystis nidulans,Biosis copyright: biol abs. rrm meeting abstract environmental contamination fresh water habitat,The effect of thallium and hexavalent chromium on the growth of anacystis nidulans Abs: Biosis copyright: biol abs. rrm meeting abstract environmental contamination fresh water habitat
1516049,Lee et al. 1975,The toxicity of a simulated refinery effluent to some fresh water animals,Heep copyright: biol abs. abstract daphnia-pulex daphnia-magna nitocris-sp aedes-aegypti dero-sp salmo-gairdneri stylaria-sp hyalella-azteca tubifex-sp goniobasis-sp cambarus-sp philodina-acuticornis dugesia-tigrina physa-sp aeolosoma-headleyi heliosoma-sp lepomis-macrochirus carassius-auratus kaolinite phenol ammonium chloride fuel oil potassium chromate sodium mono sulfide lethality,The toxicity of a simulated refinery effluent to some fresh water animals Abs: Heep copyright: biol abs. abstract daphnia-pulex daphnia-magna nitocris-sp aedes-aegypti dero-sp salmo-gairdneri stylaria-sp hyalella-azteca tubifex-sp goniobasis-sp cambarus-sp philodina-acuticornis dugesia-tigrina physa-sp aeolosoma-headleyi heliosoma-sp lepomis-macrochirus carassius-auratus kaolinite phenol ammonium chloride fuel oil potassium chromate sodium mono sulfide lethality
1516048,Lee et al. 1995,Removal of chromium from aqueous solution,"BIOSIS COPYRIGHT: BIOL ABS. Laboratory studies were conducted to assess the ability of natural moss and copper-coated moss to remove Cr(III) and Cr(VI) from aqueous solutions. Parameters investigated included pH, contact time, initial concentration, sorbent dosage and temperature. Application of the Langmuir isotherm to the systems yielded maximum sorption capacities of 18.9 and 7.1 mg/g for Cr(III) and Cr(VI), respectively. In addition, a series of flow studies was carried out using columns containing a mixture of natural and copper-coated moss. Results indicated that the treatment of aqueous solutions containing a mixture of Cr(III) and Cr(VI) using such a column is feasible.","Removal of chromium from aqueous solution Abs: BIOSIS COPYRIGHT: BIOL ABS. Laboratory studies were conducted to assess the ability of natural moss and copper-coated moss to remove Cr(III) and Cr(VI) from aqueous solutions. Parameters investigated included pH, contact time, initial concentration, sorbent dosage and temperature. Application of the Langmuir isotherm to the systems yielded maximum sorption capacities of 18.9 and 7.1 mg/g for Cr(III) and Cr(VI), respectively. In addition, a series of flow studies was carried out using columns containing a mixture of natural and copper-coated moss. Results indicated that the treatment of aqueous solutions containing a mixture of Cr(III) and Cr(VI) using such a column is feasible."
1516047,Lee 1971,Studies on the effects of cadmium on the rat's teeth and on the compensating effects of chromium,"HEEP COPYRIGHT: BIOL ABS. Healthy new-born rats (60) were divided into control, Cd-treated and Cd + Cr-treated groups. Cadmium chloride (0.1 mg) and chromium trioxide (0.1 mg) mixed with Cd (0.1 mg) were given orally from the 6th to 20th postnatal day daily. Rats were sacrficed every 6th, 10th or 20th day and serum, liver, kidney and anterior maxillary teeth were obtained. Serum levels of Ca, P and alkaline phosphatase activity were determined. Liver and kidney Cd contents were determined and histological changes of the liver, kidney and teeth were observed. The rate of body weight increase of Cd-treated rats was significantly less compared with that of the controls; the weight of the Cd + Cr-treated group was increased over that of the Cd-treated group. Serum Ca content of the Cd-treated group was slightly increased and P content decreased. Alkaline phosphatase activity in the serum of the Cd-treated group was elevated. Ca and P contents and alkaline phosphatase activity in Cd + Cr-treated group showed no significant change compared with those of controls. Accumulations of Cd in the liver and kidney of the Cd + Cr-treated group was significantly less than those in simple Cd treatment. Histologically, marked thickening of predentin and atrophy of odontoblasts were observed in the Cd-treated group but no significant change was observed in Cd + Cr-treated group. No histological findings were obtained in the liver and kidney of Cd-treated group in the Cd + Cr-treated group. Cd is considered to induce abnormal changes in the anterior teeth of young rats and Cr compensates for those effects.","Studies on the effects of cadmium on the rat's teeth and on the compensating effects of chromium Abs: HEEP COPYRIGHT: BIOL ABS. Healthy new-born rats (60) were divided into control, Cd-treated and Cd + Cr-treated groups. Cadmium chloride (0.1 mg) and chromium trioxide (0.1 mg) mixed with Cd (0.1 mg) were given orally from the 6th to 20th postnatal day daily. Rats were sacrficed every 6th, 10th or 20th day and serum, liver, kidney and anterior maxillary teeth were obtained. Serum levels of Ca, P and alkaline phosphatase activity were determined. Liver and kidney Cd contents were determined and histological changes of the liver, kidney and teeth were observed. The rate of body weight increase of Cd-treated rats was significantly less compared with that of the controls; the weight of the Cd + Cr-treated group was increased over that of the Cd-treated group. Serum Ca content of the Cd-treated group was slightly increased and P content decreased. Alkaline phosphatase activity in the serum of the Cd-treated group was elevated. Ca and P contents and alkaline phosphatase activity in Cd + Cr-treated group showed no significant change compared with those of controls. Accumulations of Cd in the liver and kidney of the Cd + Cr-treated group was significantly less than those in simple Cd treatment. Histologically, marked thickening of predentin and atrophy of odontoblasts were observed in the Cd-treated group but no significant change was observed in Cd + Cr-treated group. No histological findings were obtained in the liver and kidney of Cd-treated group in the Cd + Cr-treated group. Cd is considered to induce abnormal changes in the anterior teeth of young rats and Cr compensates for those effects."
1516046,Lazinsky and  Sicko-Goad 1990,Morphometric analysis of phosphate and chromium interactions in Cyclotella meneghiniana,BIOSIS COPYRIGHT: BIOL ABS. Quantitative electron microscopy was used to evaluate interactive effects of chromium additions and phosphate nutrient status on the diatom Cyclotella meneghiniana. Cells of differing phosphate status were exposed to hexavalent chromium for 7 days and morphological changes in both phosphate alone and phosphate and chromium treatments were observed. Changes in chloroplast relative volume and number/volume were observed in all treatments. Changes in mitochondrial and vacuolar volume and an increase in presumed autophagic activity were apparent in all chromium treatments. An increase in polyphosphate was also found in most chromium treated cells. These morphological modifications are discussed in relation to changes observed with exposure to other heavy metals.,Morphometric analysis of phosphate and chromium interactions in Cyclotella meneghiniana Abs: BIOSIS COPYRIGHT: BIOL ABS. Quantitative electron microscopy was used to evaluate interactive effects of chromium additions and phosphate nutrient status on the diatom Cyclotella meneghiniana. Cells of differing phosphate status were exposed to hexavalent chromium for 7 days and morphological changes in both phosphate alone and phosphate and chromium treatments were observed. Changes in chloroplast relative volume and number/volume were observed in all treatments. Changes in mitochondrial and vacuolar volume and an increase in presumed autophagic activity were apparent in all chromium treatments. An increase in polyphosphate was also found in most chromium treated cells. These morphological modifications are discussed in relation to changes observed with exposure to other heavy metals.
1516043,Lasheen et al. 1990,"Effect of cadmium, copper and chromium (VI) on the growth of Nile (Egypt) water algae","BIOSIS COPYRIGHT: BIOL ABS. The Algal Assay Procedure Bottle Test was used to investigate the effect of Cd, Cu, and Cr (VI) on the growth of Nile water algae. The results of this investigation indicated that Cd has slight inhibitory effects on algal growth at low concentration (0.05 mg L-1), while it was inhibiting algal growth at higher concentration ( > 1.0 mg L-1). In contrast, Cu and Cr did not affect algal growth in all investigated concentrations. Combinations of Cd with Cu and Cr seemed to interact synergistically. The synergism between Cd and Cu was more pronounced than between Cd and Cr. Clear changes in the diversity and redundancy of algal structure took place after metal addition. The inhibitory effect of the studied metals was in the following order: Cd-Cu > Cd-Cr > Cd > Cu > Cr.","Effect of cadmium, copper and chromium (VI) on the growth of Nile (Egypt) water algae Abs: BIOSIS COPYRIGHT: BIOL ABS. The Algal Assay Procedure Bottle Test was used to investigate the effect of Cd, Cu, and Cr (VI) on the growth of Nile water algae. The results of this investigation indicated that Cd has slight inhibitory effects on algal growth at low concentration (0.05 mg L-1), while it was inhibiting algal growth at higher concentration ( > 1.0 mg L-1). In contrast, Cu and Cr did not affect algal growth in all investigated concentrations. Combinations of Cd with Cu and Cr seemed to interact synergistically. The synergism between Cd and Cu was more pronounced than between Cd and Cr. Clear changes in the diversity and redundancy of algal structure took place after metal addition. The inhibitory effect of the studied metals was in the following order: Cd-Cu > Cd-Cr > Cd > Cu > Cr."
1516040,Langard et al. 1990,Incidence of Cancer among Ferrochromium and Ferrosilicon Workers: An Extended Observation Period,"The association between occupational exposure to fumes and lung cancer was investigated in a mortality cohort study extending by 5 years a previous study at a Norwegian factory producing ferrosilicon (8049170) and ferrochromium (11114468). All male employees who had worked at the factory since 1928 and who had died since 1953 were included in the cohort; the observation period for cancer incidence was 1953 through 1985. Work exposure was determined from job categories provided on personnel department lists, histories recorded by the company physician, and information supplied by employees who had worked at the factory since the 1930s. Fewer lung cancers occurred in ferrosilicon workers than expected, while the ferrochromium group demonstrated excess cases of lung and prostate cancer. Excess incidence of lung cancer was reduced slightly during the extended observation period. The standardized mortality ratio for all deaths was 81, and the standardized incidence ratio (SIR) for all cancers was 84. The SIRs for lung and prostate cancer in the ferrochromium group were 154 and 151, respectively. An overall excess of renal cancer was explained by an excess in the ferrochromium group (SIR of 273). An excess of malignant melanoma (two cases, SIR of 156) was revealed in power station and electrical workers.","Incidence of Cancer among Ferrochromium and Ferrosilicon Workers: An Extended Observation Period Abs: The association between occupational exposure to fumes and lung cancer was investigated in a mortality cohort study extending by 5 years a previous study at a Norwegian factory producing ferrosilicon (8049170) and ferrochromium (11114468). All male employees who had worked at the factory since 1928 and who had died since 1953 were included in the cohort; the observation period for cancer incidence was 1953 through 1985. Work exposure was determined from job categories provided on personnel department lists, histories recorded by the company physician, and information supplied by employees who had worked at the factory since the 1930s. Fewer lung cancers occurred in ferrosilicon workers than expected, while the ferrochromium group demonstrated excess cases of lung and prostate cancer. Excess incidence of lung cancer was reduced slightly during the extended observation period. The standardized mortality ratio for all deaths was 81, and the standardized incidence ratio (SIR) for all cancers was 84. The SIRs for lung and prostate cancer in the ferrochromium group were 154 and 151, respectively. An overall excess of renal cancer was explained by an excess in the ferrochromium group (SIR of 273). An excess of malignant melanoma (two cases, SIR of 156) was revealed in power station and electrical workers."
1516039,Langard 1982,"Absorption, Transport and Excretion of Chromium in Man and Animals","The most important factors and mechanisms which influence the availability of chromium (7440473) bearing compounds at their sites of action were reviewed and discussed. Emphasis was placed on toxic compounds. Specific topics reviewed include the daily requirement of chromium in man including chromium concentrations in blood and normal levels of chromium in the tissues; uptake of chromium in the airways of humans (including the significance of the particle size distribution, trivalent chromium compounds, and hexavalent chromium compounds), uptake in the airways of animals, uptake in the gastrointestinal tract and uptake through the skin; transport and distribution in the body including uptake in living cells, tissue distribution in animals, chromic compounds, chromates, tissue distribution in exposed man, and transport through the placenta; excretion including urinary excretion and excretion in the bile and gastrointestinal tract; and biological monitoring of occupationally exposed workers. According to the author, while routine monitoring of workers does not appear warranted, particular disturbances in carbohydrate metabolism or severe protein deficiency may be considered as indications that monitoring may be useful. From a practical point of view, blood and urine are the only biological materials which are available for measurement of chromium concentrations in exposed workers.","Absorption, Transport and Excretion of Chromium in Man and Animals Abs: The most important factors and mechanisms which influence the availability of chromium (7440473) bearing compounds at their sites of action were reviewed and discussed. Emphasis was placed on toxic compounds. Specific topics reviewed include the daily requirement of chromium in man including chromium concentrations in blood and normal levels of chromium in the tissues; uptake of chromium in the airways of humans (including the significance of the particle size distribution, trivalent chromium compounds, and hexavalent chromium compounds), uptake in the airways of animals, uptake in the gastrointestinal tract and uptake through the skin; transport and distribution in the body including uptake in living cells, tissue distribution in animals, chromic compounds, chromates, tissue distribution in exposed man, and transport through the placenta; excretion including urinary excretion and excretion in the bile and gastrointestinal tract; and biological monitoring of occupationally exposed workers. According to the author, while routine monitoring of workers does not appear warranted, particular disturbances in carbohydrate metabolism or severe protein deficiency may be considered as indications that monitoring may be useful. From a practical point of view, blood and urine are the only biological materials which are available for measurement of chromium concentrations in exposed workers."
1516037,Lagerspetz et al. 1993,Low sensitivity of ciliary activity in the gills of Anodonta cygnea to some ecotoxicals,"BIOSIS COPYRIGHT: BIOL ABS. 1. The effects of some ecotoxical model substances on the activity of frontal gill cilia of freshwater mussel Anodonta cygnea were studied in 1 and 24 hr experiments with the particle transport method. The effects were compared with the results of standard Daphnia magna EC50 tests with the same substances. 2. Variations of pH between 4.8 and 8.1 affected the ciliary activity by less than 30%. 3. Ciliary activity was less sensitive to heavy metal salts, sodium lauryl sulphate and to two pulp industry waste model substances than D. magna. 4. Compared to D. magna, the ciliary activity was more sensitive to formalin and 2,4-dinitrophenol, and as sensitive to ethanol. 5. Ciliary activity in bivalve gills is a well regulated and/or a relative insensitive function, but it may be used as a rapid screening test for some cell ecotoxicals.","Low sensitivity of ciliary activity in the gills of Anodonta cygnea to some ecotoxicals Abs: BIOSIS COPYRIGHT: BIOL ABS. 1. The effects of some ecotoxical model substances on the activity of frontal gill cilia of freshwater mussel Anodonta cygnea were studied in 1 and 24 hr experiments with the particle transport method. The effects were compared with the results of standard Daphnia magna EC50 tests with the same substances. 2. Variations of pH between 4.8 and 8.1 affected the ciliary activity by less than 30%. 3. Ciliary activity was less sensitive to heavy metal salts, sodium lauryl sulphate and to two pulp industry waste model substances than D. magna. 4. Compared to D. magna, the ciliary activity was more sensitive to formalin and 2,4-dinitrophenol, and as sensitive to ethanol. 5. Ciliary activity in bivalve gills is a well regulated and/or a relative insensitive function, but it may be used as a rapid screening test for some cell ecotoxicals."
1516036,Kwok 1987,Prevention of Cement Dermatitis in Construction Workers with Iron Sulphate AU - Goh CL,"A study was initiated to determine the amount of iron-sulfate needed to successfully remove hexavalent chromate (18540299) from nine different brands of Asian cement in order to reduce the risk of contact dermatitis. Worker sick days due to allergic dermatitis in the construction business in Singapore had amounted to 53 days/year. Even with avoidance of cement for a period of time, the reaction did not always clear up. Content of chromate in the nine cements ranged from 3.6 to 25.1 micrograms/gram. The amounts of ferrous-sulfate tested were 0.2, 0.3, 0.35, 0.5, and 1 percent weight/weight of cement. In all cements, only a very small amount of iron-sulfate, 0.35 percent weight/weight, was needed to remove all detectable hexavalent chromate. The use of more iron-sulfate than required is cautioned against as it may change the properties of the concrete and increase the cost. Use of 0.35 percent resulted in no changes in setting time, compressive strength, static modulus of elasticity, shrinkage, or creep of the concrete produced. The authors recommend the use of iron-sulfate for removal of hexavalent chromium and prevention of cement dermatitis.","Prevention of Cement Dermatitis in Construction Workers with Iron Sulphate AU - Goh CL Abs: A study was initiated to determine the amount of iron-sulfate needed to successfully remove hexavalent chromate (18540299) from nine different brands of Asian cement in order to reduce the risk of contact dermatitis. Worker sick days due to allergic dermatitis in the construction business in Singapore had amounted to 53 days/year. Even with avoidance of cement for a period of time, the reaction did not always clear up. Content of chromate in the nine cements ranged from 3.6 to 25.1 micrograms/gram. The amounts of ferrous-sulfate tested were 0.2, 0.3, 0.35, 0.5, and 1 percent weight/weight of cement. In all cements, only a very small amount of iron-sulfate, 0.35 percent weight/weight, was needed to remove all detectable hexavalent chromate. The use of more iron-sulfate than required is cautioned against as it may change the properties of the concrete and increase the cost. Use of 0.35 percent resulted in no changes in setting time, compressive strength, static modulus of elasticity, shrinkage, or creep of the concrete produced. The authors recommend the use of iron-sulfate for removal of hexavalent chromium and prevention of cement dermatitis."
1516035,Kusuda et al. 1986,Standardization of water quality information in a tidal river,Biosis copyright: biol abs. rrm human rokkaku river japan cadmium lead cyanide chromium phosphorus arsenic polychlorinated biphenyl mercury turbidity metal pollution water pollution,Standardization of water quality information in a tidal river Abs: Biosis copyright: biol abs. rrm human rokkaku river japan cadmium lead cyanide chromium phosphorus arsenic polychlorinated biphenyl mercury turbidity metal pollution water pollution
1516034,Kuschner 1978,Cellular Transformations,"Cellular transformations are discussed in relation to occupational carcinogenesis and experimental medicine. The use of animal models in cancer research, particularly in studies of inhalation cancer, is reviewed. The irritative effects of sulfite (14265453) in carcinoma production are noted, emphasizing the increased incidence of cancer among coke oven operators and workers exposed to roofing tar. Hexavalent-chromium (18540299) as calcium-chromate (13765190) is cited as the source of a 10 fold increase in the incidence of lung cancer in chromate workers. Ionizing radiation from radon and radon daughters is identified as the cause of lung cancer in uranium mine workers. A dose effect for ionizing radiation is shown to be experimentally validated. The effects of industrial byproducts on the general population are reconsidered. The author suggests that the microenvironment created by the individual for himself is a major characteristic in cancer induction.","Cellular Transformations Abs: Cellular transformations are discussed in relation to occupational carcinogenesis and experimental medicine. The use of animal models in cancer research, particularly in studies of inhalation cancer, is reviewed. The irritative effects of sulfite (14265453) in carcinoma production are noted, emphasizing the increased incidence of cancer among coke oven operators and workers exposed to roofing tar. Hexavalent-chromium (18540299) as calcium-chromate (13765190) is cited as the source of a 10 fold increase in the incidence of lung cancer in chromate workers. Ionizing radiation from radon and radon daughters is identified as the cause of lung cancer in uranium mine workers. A dose effect for ionizing radiation is shown to be experimentally validated. The effects of industrial byproducts on the general population are reconsidered. The author suggests that the microenvironment created by the individual for himself is a major characteristic in cancer induction."
1516033,Kuo and  Genthner 1996,Effect of added heavy metal ions on biotransformation and biodegradation of 2-chlorophenol and 3-chlorobenzoate in anaerobic bacterial consortia,"BIOSIS COPYRIGHT: BIOL ABS. The effect of added Cd(II), Cu(II), Cr(VI), or Hg(II) at 0.01 to 100 ppm on metabolism in anaerobic bacterial consortia which degrade 2-chlorophenol (2CP), 3-chlorobenzoate (3CB), phenol, and benzoate was examined. Three effects were observed, including extended acclimation periods (0.1 to 2.0 ppm), reduced dechlorination or biodegradation rates (0.1 to 2.0 ppm), and failure to dechlorinate or biodegrade the target compound (0.5 to 5.0 ppm). 3CB biodegradation was most sensitive to Cd(II) and Cr(VI). Biodegradation of benzoate and phenol was most sensitive to Cu(II) and Hg(II), respectively. Adding Cr(VI) at 0.01 ppm increased biodegradation rates of phenol (177%) and benzoate (169%), while Cd(II) and Cu(II) at 0.01 ppm enhanced biodegradation rates of benzoate (185%) and 2CP (168%), respectively. Interestingly, with Hg(II) at 1.0 to 2.0 ppm, 2CP and 3CB were biodegraded 133 to 154% faster than controls after an extended acclimation period, suggesting adaptation to Hg(I","Effect of added heavy metal ions on biotransformation and biodegradation of 2-chlorophenol and 3-chlorobenzoate in anaerobic bacterial consortia Abs: BIOSIS COPYRIGHT: BIOL ABS. The effect of added Cd(II), Cu(II), Cr(VI), or Hg(II) at 0.01 to 100 ppm on metabolism in anaerobic bacterial consortia which degrade 2-chlorophenol (2CP), 3-chlorobenzoate (3CB), phenol, and benzoate was examined. Three effects were observed, including extended acclimation periods (0.1 to 2.0 ppm), reduced dechlorination or biodegradation rates (0.1 to 2.0 ppm), and failure to dechlorinate or biodegrade the target compound (0.5 to 5.0 ppm). 3CB biodegradation was most sensitive to Cd(II) and Cr(VI). Biodegradation of benzoate and phenol was most sensitive to Cu(II) and Hg(II), respectively. Adding Cr(VI) at 0.01 ppm increased biodegradation rates of phenol (177%) and benzoate (169%), while Cd(II) and Cu(II) at 0.01 ppm enhanced biodegradation rates of benzoate (185%) and 2CP (168%), respectively. Interestingly, with Hg(II) at 1.0 to 2.0 ppm, 2CP and 3CB were biodegraded 133 to 154% faster than controls after an extended acclimation period, suggesting adaptation to Hg(I"
1516032,Kuo and  Genthner 1995,Effect of heavy metal ions on the biodegradation of halogenated and nonhalogenated aromatic compounds by anaerobic bacterial consortia,Biosis copyright: biol abs. rrm meeting abstract heavy metal pollution,Effect of heavy metal ions on the biodegradation of halogenated and nonhalogenated aromatic compounds by anaerobic bacterial consortia Abs: Biosis copyright: biol abs. rrm meeting abstract heavy metal pollution
1516029,Knoll et al. 1990,Development of a source test method for hexavalent chromium,,Development of a source test method for hexavalent chromium Abs: 
1516028,Kubinski and  Kubinski 1982,Further studies on the co-transformation of distant markers following the exposure of DNA to carcinogens including carcinogenic metals,HEEP COPYRIGHT: BIOL ABS. ABSTRACT BACILLUS-SUBTILIS CHROMIUM VI N ACETOXY-2-ACETYLAMINO FLUORENE CARCINOGEN CHROMOSOMAL MARKER MACRO MOLECULAR COMPLEX,Further studies on the co-transformation of distant markers following the exposure of DNA to carcinogens including carcinogenic metals Abs: HEEP COPYRIGHT: BIOL ABS. ABSTRACT BACILLUS-SUBTILIS CHROMIUM VI N ACETOXY-2-ACETYLAMINO FLUORENE CARCINOGEN CHROMOSOMAL MARKER MACRO MOLECULAR COMPLEX
1516027,Krull et al. 1983,Trace analysis and speciation for chromium(VI) and chromium(III) via high performance liquid chromatography-direct current plasma emission spectroscopy,"HEEP COPYRIGHT: BIOL ABS. High performance liquid chromatography (HPLC) can be rapidly, easily and inexpensively interfaced with a commercial direct current plasma (DCP) emission spectrometer in order to obtain overall instrumentation useful for the trace analysis and speciation of at least 2 Cr species via HPLC-DCP, i.e., Cr(III)and Cr(VI) ions are soluble in aqueous media compatible with HPLC injection/separation methods. The HPLC separations of the 2 Cr ions are readily accomplished using paired-ion, reversed-phase conditions, with either a tetrabutylammonium counter-ion or a camphor sulfonate counter-ion in solution. The order of elution of the 2 Cr ions is completely reversed in going from one counter-ion to the other in the mobile phase. These HPLC conditions are interfaced with a conventional DCP spectrometer utilizing nothing more than a short length of narrow-bore plastic tubing between the end of the HPLC column and the sample introduction orifice on the DCP spray chamber. It is possible using this HPLC-DCP approach to obtain detection limits for both Cr species in the range of 5-10 ppb, with at least 3-4 orders of magnitude linearity in the calibration plots. This was demonstrated with both retained and unretained HPLC conditions for both Cr species. These overall methods of analysis and speciation were applied to a number of spiked water samples, an NBS (National Burean of Standards) Cr water standard, several environmental water samples, various biological samples from the Atlantic Ocean, and 2 Maine tannery samples. These particular HPLC-DCP methods of speciation may be uniquely appropriate and applicable for most environmental, biological, toxicological and/or consumer product samples, wherein Cr contamination may be a suspected or known problem.","Trace analysis and speciation for chromium(VI) and chromium(III) via high performance liquid chromatography-direct current plasma emission spectroscopy Abs: HEEP COPYRIGHT: BIOL ABS. High performance liquid chromatography (HPLC) can be rapidly, easily and inexpensively interfaced with a commercial direct current plasma (DCP) emission spectrometer in order to obtain overall instrumentation useful for the trace analysis and speciation of at least 2 Cr species via HPLC-DCP, i.e., Cr(III)and Cr(VI) ions are soluble in aqueous media compatible with HPLC injection/separation methods. The HPLC separations of the 2 Cr ions are readily accomplished using paired-ion, reversed-phase conditions, with either a tetrabutylammonium counter-ion or a camphor sulfonate counter-ion in solution. The order of elution of the 2 Cr ions is completely reversed in going from one counter-ion to the other in the mobile phase. These HPLC conditions are interfaced with a conventional DCP spectrometer utilizing nothing more than a short length of narrow-bore plastic tubing between the end of the HPLC column and the sample introduction orifice on the DCP spray chamber. It is possible using this HPLC-DCP approach to obtain detection limits for both Cr species in the range of 5-10 ppb, with at least 3-4 orders of magnitude linearity in the calibration plots. This was demonstrated with both retained and unretained HPLC conditions for both Cr species. These overall methods of analysis and speciation were applied to a number of spiked water samples, an NBS (National Burean of Standards) Cr water standard, several environmental water samples, various biological samples from the Atlantic Ocean, and 2 Maine tannery samples. These particular HPLC-DCP methods of speciation may be uniquely appropriate and applicable for most environmental, biological, toxicological and/or consumer product samples, wherein Cr contamination may be a suspected or known problem."
1516026,Krishnan 1983,Recovery of heavy metals from steelmaking dust,"HMTC Almost two million metric tons of dusts containing iron, zinc, and lead are produced annually by the steelmaking industry. This dust originates from open hearth furnaces (OH), basic oxygen furnaces (BOF), and electric arc furnaces (EAF). EAF dust is currently listed as a hazardous waste because of its toxic constituents: lead, cadmium, and hexavalent chromium. Because it is a hazardous waste, the dust must be encapsulated or transported to a controlled landfill. Since disposal sites are becoming scarcer, the steelmaking industry is looking for variable options for handling dust. Recovery alternatives are being investigated since the dust represents a potential source of valuable elements such as iron and zinc. Three smelting technologies feasible for the recovery of heavy metals from carbon-steel EAF dusts are the caustic leach electrolytic smelting process, and two pyrometallurgical smelting techniques: the Waelz-kiln process and a process using an electrothermic shaft furnace. An assessment of these technologies reveals that the two pyrometallurgical smelting techniques appear to be the most feasible at this time; however, detailed economic analyses are required. (13 ref.)","Recovery of heavy metals from steelmaking dust Abs: HMTC Almost two million metric tons of dusts containing iron, zinc, and lead are produced annually by the steelmaking industry. This dust originates from open hearth furnaces (OH), basic oxygen furnaces (BOF), and electric arc furnaces (EAF). EAF dust is currently listed as a hazardous waste because of its toxic constituents: lead, cadmium, and hexavalent chromium. Because it is a hazardous waste, the dust must be encapsulated or transported to a controlled landfill. Since disposal sites are becoming scarcer, the steelmaking industry is looking for variable options for handling dust. Recovery alternatives are being investigated since the dust represents a potential source of valuable elements such as iron and zinc. Three smelting technologies feasible for the recovery of heavy metals from carbon-steel EAF dusts are the caustic leach electrolytic smelting process, and two pyrometallurgical smelting techniques: the Waelz-kiln process and a process using an electrothermic shaft furnace. An assessment of these technologies reveals that the two pyrometallurgical smelting techniques appear to be the most feasible at this time; however, detailed economic analyses are required. (13 ref.)"
1516025,Krishnamurthy and  Wilkens 1994,Environmental chemistry of chromium,"BIOSIS COPYRIGHT: BIOL ABS. Chromium is of great environmental concern because hexavalent chromium is a potent carcinogen. The health effects resulting from chromium exposure have received as much attention as those resulting from benzene or asbestos exposure. Although considered innocuous, Cr(III) can be mutagenic and genotoxic when inside the nuclei of cells in target organs. This paper discusses the various oxidation states of the metal in the environment, the interconversion of Cr(III) and Cr(VI), the sources of chromium in the environment, and the transport of the metal in the media. Chromium's tendency to change oxidation states, in both environmental media and living cells, is emphasized. It is possible for Cr(VI) to become immobilized in aquifers in a solid phase as barium chromate. This may present a problem in remediation by ""Pump and Treat"" technology if the solid phase cannot be easily solubilized. The microbial reduction of hexavalent chromium and bioremediation of chromium-contaminat MH - ANIMALS","Environmental chemistry of chromium Abs: BIOSIS COPYRIGHT: BIOL ABS. Chromium is of great environmental concern because hexavalent chromium is a potent carcinogen. The health effects resulting from chromium exposure have received as much attention as those resulting from benzene or asbestos exposure. Although considered innocuous, Cr(III) can be mutagenic and genotoxic when inside the nuclei of cells in target organs. This paper discusses the various oxidation states of the metal in the environment, the interconversion of Cr(III) and Cr(VI), the sources of chromium in the environment, and the transport of the metal in the media. Chromium's tendency to change oxidation states, in both environmental media and living cells, is emphasized. It is possible for Cr(VI) to become immobilized in aquifers in a solid phase as barium chromate. This may present a problem in remediation by ""Pump and Treat"" technology if the solid phase cannot be easily solubilized. The microbial reduction of hexavalent chromium and bioremediation of chromium-contaminat MH - ANIMALS"
1516023,Kratochvil et al. 1998,Removal of trivalent and hexavalent chromium by seaweed biosorbent,"BIOSIS COPYRIGHT: BIOL ABS. Protonated or Ca-form Sargassum seaweed biomass bound up to 40 mg/g of Cr(III) by ion exchange at pH 4. An ion-exchange model assuming that the only species taken up by the biomass was Cr(OH)2+ successfully fitted the experimental biosorption data for Cr(III). The maximum uptake of Cr(VI) by protonated Sargassum biomass at pH 2 was explained by simultaneous anion exchange and Cr(VI) to Cr(III) reduction. At pH < 2.0, the reduction of Cr(VI) to Cr(III) dominated the equilibrium behavior of the batch systems, which was explained by the dependence of the reduction potential of HCrO4- ions on the pH. At pH > 2.0, the removal of Cr(VI) was linked to the depletion of protons in equilibrium batch systems via an anion-exchange reaction. The optimum pH for Cr(VI) removal by sorption lies in the region where the two mechanisms overlap, which for Sargassum biomass is in the vicinity of pH 2. The existence of the optimum pH for the removal of Cr(VI) may be explained by taking i","Removal of trivalent and hexavalent chromium by seaweed biosorbent Abs: BIOSIS COPYRIGHT: BIOL ABS. Protonated or Ca-form Sargassum seaweed biomass bound up to 40 mg/g of Cr(III) by ion exchange at pH 4. An ion-exchange model assuming that the only species taken up by the biomass was Cr(OH)2+ successfully fitted the experimental biosorption data for Cr(III). The maximum uptake of Cr(VI) by protonated Sargassum biomass at pH 2 was explained by simultaneous anion exchange and Cr(VI) to Cr(III) reduction. At pH < 2.0, the reduction of Cr(VI) to Cr(III) dominated the equilibrium behavior of the batch systems, which was explained by the dependence of the reduction potential of HCrO4- ions on the pH. At pH > 2.0, the removal of Cr(VI) was linked to the depletion of protons in equilibrium batch systems via an anion-exchange reaction. The optimum pH for Cr(VI) removal by sorption lies in the region where the two mechanisms overlap, which for Sargassum biomass is in the vicinity of pH 2. The existence of the optimum pH for the removal of Cr(VI) may be explained by taking i"
1516022,Kozaric et al. 1993,Short-term effect of hexavalent chromium in water on glycogen content and activities of some enzymes involved in carbohydrate metabolism in the liver of the carp (Cyprinus carpio L.),"BIOSIS COPYRIGHT: BIOL ABS. Carp (Cyprinus carpio L.) were exposed to three test concentrations of 3.95, 5.92 and 7.90 ppm of chromium in water for 4 days. The liver glycogen content and activities of glucose-6-phosphatase, glucose-6-phosphate dehydrogenase, phosphoglucomutase and glucose-phosphate isomerase were determined by histochemical methods. The activity of glucose-6-phosphatase was inhibited at 3.95 ppm of chromium and stimulated at higher investigated chromium concentrations. Hexokinase activity was inhibited only at 7.90 ppm and phosphoglucomutase at 5.92 ppm of chromium. The activities of glucose-phosphate isomerase and glucose-6-phosphate dehydrogenase were also inhibited, and the liver glycogen content increased in correlation with the decrease of the chromium concentration in water.","Short-term effect of hexavalent chromium in water on glycogen content and activities of some enzymes involved in carbohydrate metabolism in the liver of the carp (Cyprinus carpio L.) Abs: BIOSIS COPYRIGHT: BIOL ABS. Carp (Cyprinus carpio L.) were exposed to three test concentrations of 3.95, 5.92 and 7.90 ppm of chromium in water for 4 days. The liver glycogen content and activities of glucose-6-phosphatase, glucose-6-phosphate dehydrogenase, phosphoglucomutase and glucose-phosphate isomerase were determined by histochemical methods. The activity of glucose-6-phosphatase was inhibited at 3.95 ppm of chromium and stimulated at higher investigated chromium concentrations. Hexokinase activity was inhibited only at 7.90 ppm and phosphoglucomutase at 5.92 ppm of chromium. The activities of glucose-phosphate isomerase and glucose-6-phosphate dehydrogenase were also inhibited, and the liver glycogen content increased in correlation with the decrease of the chromium concentration in water."
1516021,Kouzeli-Katsiri et al. 1988,Assessment of the toxicity of heavy metals to the anaerobic digestion of sewage sludge,Biosis copyright: biol abs. rrm waste management wastewater treatment water pollution,Assessment of the toxicity of heavy metals to the anaerobic digestion of sewage sludge Abs: Biosis copyright: biol abs. rrm waste management wastewater treatment water pollution
1516018,Koshima and  Onishi 1986,Adsorption of metal ions on activated carbon from aqueous solutions at ph 1-13,Biosis copyright: biol abs. rrm cesium-i yttrium-iii cerium-iii titanium-iv zirconium-iv chromium-iii chromium-vi manganese-ii iron-iii cobalt-ii cadmium-ii nickel-ii aluminum-iii ruthenium-iii lead-ii copper-ii antimony-iii silver-i bismuth-iii zinc-ii environment,Adsorption of metal ions on activated carbon from aqueous solutions at ph 1-13 Abs: Biosis copyright: biol abs. rrm cesium-i yttrium-iii cerium-iii titanium-iv zirconium-iv chromium-iii chromium-vi manganese-ii iron-iii cobalt-ii cadmium-ii nickel-ii aluminum-iii ruthenium-iii lead-ii copper-ii antimony-iii silver-i bismuth-iii zinc-ii environment
1516014,Koropchak and  Roychowdhury 1990,Evidence for aerosol ionic redistribution within aerosols produced by chrome electroplating,"BIOSIS COPYRIGHT: BIOL ABS. Particle size and chemical speciation are significant factors in the assessment of the environmental impact of chromium aerosols, with chromium(VI) and smaller particles being most hazardous. In this report, aerosols from a chrome-electroplating shop were collected by use of a cascade impactor to provide size-selective information. Species selectivity was provided by liquid chromatography coupled with inductively coupled plasma atomic emission spectrometry for the analysis of extracts from impaction stages. Data generated indicated that particle size distributions are affected by environmental conditions and that the ratio of chromium(VI) to chromium(III) increased as particle size decreased. The latter effect was attributed to aerosol ionic redistribution occurring during aerosol formation.","Evidence for aerosol ionic redistribution within aerosols produced by chrome electroplating Abs: BIOSIS COPYRIGHT: BIOL ABS. Particle size and chemical speciation are significant factors in the assessment of the environmental impact of chromium aerosols, with chromium(VI) and smaller particles being most hazardous. In this report, aerosols from a chrome-electroplating shop were collected by use of a cascade impactor to provide size-selective information. Species selectivity was provided by liquid chromatography coupled with inductively coupled plasma atomic emission spectrometry for the analysis of extracts from impaction stages. Data generated indicated that particle size distributions are affected by environmental conditions and that the ratio of chromium(VI) to chromium(III) increased as particle size decreased. The latter effect was attributed to aerosol ionic redistribution occurring during aerosol formation."
1516011,Kong et al. 1993,Competing ion effect on chromium adsorption with fresh and starved subsurface bacterial consortium,"BIOSIS COPYRIGHT: BIOL ABS. The sorption of chromium (Cr+6) was investigated for 50 day starved and fresh cells in the presence of sulfatelion as a competing ion at three pH values (pH 6.0, 7.5 and 9.0). The chromium distribution in the subcellular components was also determined by conducting cell fractionation. Although a previous study showed that cells which had been starved for 50 days prior to being exposed to a chromium containing solution sorbed 10-15% more chromium than did fresh cells (Kong et al., 1992a), this study demonstrated that such cells did not sorb more chromium in the presence of sulfate ion.","Competing ion effect on chromium adsorption with fresh and starved subsurface bacterial consortium Abs: BIOSIS COPYRIGHT: BIOL ABS. The sorption of chromium (Cr+6) was investigated for 50 day starved and fresh cells in the presence of sulfatelion as a competing ion at three pH values (pH 6.0, 7.5 and 9.0). The chromium distribution in the subcellular components was also determined by conducting cell fractionation. Although a previous study showed that cells which had been starved for 50 days prior to being exposed to a chromium containing solution sorbed 10-15% more chromium than did fresh cells (Kong et al., 1992a), this study demonstrated that such cells did not sorb more chromium in the presence of sulfate ion."
1516007,Komori et al. 1990,Effects of oxygen stress on chromate reduction in Enterobacter cloacae strain HO1,"BIOSIS COPYRIGHT: BIOL ABS. Enterobacter cloacae strain HO1 was able to reduce toxic hexavalent chromium (chromate) anaerobically. The reduction of chromate by E. cloacae cells was sensitive to oxygen stress. Cultures under continuous aeration showed no chromate reduction. However, when released from the oxygen stress, the cultures readily resumed chromate reduction.","Effects of oxygen stress on chromate reduction in Enterobacter cloacae strain HO1 Abs: BIOSIS COPYRIGHT: BIOL ABS. Enterobacter cloacae strain HO1 was able to reduce toxic hexavalent chromium (chromate) anaerobically. The reduction of chromate by E. cloacae cells was sensitive to oxygen stress. Cultures under continuous aeration showed no chromate reduction. However, when released from the oxygen stress, the cultures readily resumed chromate reduction."
1516003,Klein 1987,A Demonstration of NIOSH Push-Pull Ventilation Criteria,"The results of a study of a push pull (PP) ventilation system on a chrome plating tank were summarized. The design of the demonstration tank was similar to that of the laboratory tank developed by Huebener and Hughes. The initial push and pull settings were, respectively, 0.034 cubic meters per second per meter (m3/sec/m) and 0.36 cubic meters per second per square meter (m3/sec/m2). Also included in the tests was the lowest possible push setting of 0.22m3/sec/m. Industrial hygiene samples were taken for hexavalent chromium (18540299) (Cr(VI)) and total chrome (7440473). The process operating parameters were checked every hour during production and dummy runs. The PP system at the study setting controlled the total chrome emissions from the plating process to below the OSHA standards and the NIOSH and ACGIH guidelines. The overall Cr(VI) levels were below the OSHA and ACGIH limits but exceeded the NIOSH recommendations for the two lower push settings. However, the PP system was believed to have controlled Cr(VI) levels to within the NIOSH levels, because the samples were collected near the tank under heavier exposure conditions than would be experienced by workers. The Statistical analysis of the data showed the ability of the PP system to compensate for interferences in the flow of the push air. The lack of significant differences between production run and dummy loads indicated that evaporation from the plated parts and baskets, when they were out of the tank, did not affect air concentration significantly. The system worked at a push setting lower than the range found by Huebener. The author states that adjustments to Huebener's results are needed to compensate for different nozzle construction and environmental conditions.","A Demonstration of NIOSH Push-Pull Ventilation Criteria Abs: The results of a study of a push pull (PP) ventilation system on a chrome plating tank were summarized. The design of the demonstration tank was similar to that of the laboratory tank developed by Huebener and Hughes. The initial push and pull settings were, respectively, 0.034 cubic meters per second per meter (m3/sec/m) and 0.36 cubic meters per second per square meter (m3/sec/m2). Also included in the tests was the lowest possible push setting of 0.22m3/sec/m. Industrial hygiene samples were taken for hexavalent chromium (18540299) (Cr(VI)) and total chrome (7440473). The process operating parameters were checked every hour during production and dummy runs. The PP system at the study setting controlled the total chrome emissions from the plating process to below the OSHA standards and the NIOSH and ACGIH guidelines. The overall Cr(VI) levels were below the OSHA and ACGIH limits but exceeded the NIOSH recommendations for the two lower push settings. However, the PP system was believed to have controlled Cr(VI) levels to within the NIOSH levels, because the samples were collected near the tank under heavier exposure conditions than would be experienced by workers. The Statistical analysis of the data showed the ability of the PP system to compensate for interferences in the flow of the push air. The lack of significant differences between production run and dummy loads indicated that evaporation from the plated parts and baskets, when they were out of the tank, did not affect air concentration significantly. The system worked at a push setting lower than the range found by Huebener. The author states that adjustments to Huebener's results are needed to compensate for different nozzle construction and environmental conditions."
1516002,Kleiman and  Cogliatti 1998,Chromium removal from aqueous solutions by different plant species,"BIOSIS COPYRIGHT: BIOL ABS. The aim of this study was to evaluate the potential efficiency of three plant species to remove chromium from wastewaters. Wheat (Triticum aestivum), rape (Brassica napus var. Oleracea) and buckwheat (Fagopyrum esculentum) were grown hydroponically under controlled conditions. The uptake of Cr(III) and Cr(VI), and its effect on plant growth were measured in culture solution. Cr(VI) was more toxic than Cr(III). In all species, Cr(III) affected growth only at the highest concentration, while Cr(VI) was toxic at lower concentrations. Plant Cr-concentration was far higher in the root than in the shoot of the three plant species grown with both Cr(III) or Cr(VI). Plants grown in Cr(III) showed higher tissue concentration and chromium removal efficiency than those grown in Cr(VI). In Cr(III), Cr-oxide and hydroxide precipitation on root surface was observed. It can be suggested that plant roots act as a powerful agent of Cr(III) removal and that a greater amount of plant root","Chromium removal from aqueous solutions by different plant species Abs: BIOSIS COPYRIGHT: BIOL ABS. The aim of this study was to evaluate the potential efficiency of three plant species to remove chromium from wastewaters. Wheat (Triticum aestivum), rape (Brassica napus var. Oleracea) and buckwheat (Fagopyrum esculentum) were grown hydroponically under controlled conditions. The uptake of Cr(III) and Cr(VI), and its effect on plant growth were measured in culture solution. Cr(VI) was more toxic than Cr(III). In all species, Cr(III) affected growth only at the highest concentration, while Cr(VI) was toxic at lower concentrations. Plant Cr-concentration was far higher in the root than in the shoot of the three plant species grown with both Cr(III) or Cr(VI). Plants grown in Cr(III) showed higher tissue concentration and chromium removal efficiency than those grown in Cr(VI). In Cr(III), Cr-oxide and hydroxide precipitation on root surface was observed. It can be suggested that plant roots act as a powerful agent of Cr(III) removal and that a greater amount of plant root"
1516000,Kiyak et al. 1999,Cr(VI) reduction in aqueous solutions by using copper smelter slag,"BIOSIS COPYRIGHT: BIOL ABS. The ability of Copper Smelter Slag (CSS) to reduce Cr(VI) in aqueous solutions has been investigated. The extent of reduction is dependent on the amounts of acid and reductant, contact time, Cr(VI) concentration, temperature of the solution and particle size of CSS. The amount of acid is the most important variable affecting the reduction process. When twice the amount of acid required with respect to Cr(VI) was used, Cr(VI) in 100 ml solution (100 mg/l) was completely reduced in a contact perio","Cr(VI) reduction in aqueous solutions by using copper smelter slag Abs: BIOSIS COPYRIGHT: BIOL ABS. The ability of Copper Smelter Slag (CSS) to reduce Cr(VI) in aqueous solutions has been investigated. The extent of reduction is dependent on the amounts of acid and reductant, contact time, Cr(VI) concentration, temperature of the solution and particle size of CSS. The amount of acid is the most important variable affecting the reduction process. When twice the amount of acid required with respect to Cr(VI) was used, Cr(VI) in 100 ml solution (100 mg/l) was completely reduced in a contact perio"
1515999,Kitagawa et al. 1988,EPR Study on the Interaction of Hexavalent Chromium with Glutathione or Cysteine: Production of Pentavalent Chromium and its Stability,"To elucidate the characteristics of pentavalent chromium (Cr-V) production in the reaction of thiol compounds with hexavalent chromium (18540299) (Cr-VI), electron paramagnetic spin resonance (EPR) spectrometry was used to study the pH dependency of the production of Cr-V over a wide pH range (pH 3.0 to 8.0) for the reaction of Cr-VI with glutathione or cysteine. At all pH values above 5.0, two Cr-V species, characterized by g values of 1.005 to 1.996 and 1.985 to 1.986 were detected. At pH 3.0 and 4.0 a single species of Cr-V with a g-value of 1.989 to 1.990 was noted. At pH 7.0 the Cr-V species were relatively long lived and most stable. Signals of two Cr-V species were watched for more than 30 minutes. A pH dependence was noted in the intensities of the Cr-V signals which increased with increases in pH from 3.0 to 8.0. The signal corresponding to the species of the larger g-value increased markedly with an increase in glutathione concentration at neutral pH. EPR measurements at 77 degrees-K confirmed the stable production of Cr-V by glutathione. Characteristics of Cr-V generation by cysteine were quite different. The production of the Cr-V species was confirmed by a sharp single signal with a g-value of 1.984 to 1.987. The signal intensity corresponding to Cr-V generation did not change much with a change in pH from 3.0 to 6.0. Only a small signal was noted a pH 7.0. No signal was noted at pH 8.0. The lifetime of the Cr-V signal was shorter than that observed for the reduction with glutathione. The authors conclude that Cr-V may be stabilized in glutathione solution by its suitable redox potential and ligand structure.","EPR Study on the Interaction of Hexavalent Chromium with Glutathione or Cysteine: Production of Pentavalent Chromium and its Stability Abs: To elucidate the characteristics of pentavalent chromium (Cr-V) production in the reaction of thiol compounds with hexavalent chromium (18540299) (Cr-VI), electron paramagnetic spin resonance (EPR) spectrometry was used to study the pH dependency of the production of Cr-V over a wide pH range (pH 3.0 to 8.0) for the reaction of Cr-VI with glutathione or cysteine. At all pH values above 5.0, two Cr-V species, characterized by g values of 1.005 to 1.996 and 1.985 to 1.986 were detected. At pH 3.0 and 4.0 a single species of Cr-V with a g-value of 1.989 to 1.990 was noted. At pH 7.0 the Cr-V species were relatively long lived and most stable. Signals of two Cr-V species were watched for more than 30 minutes. A pH dependence was noted in the intensities of the Cr-V signals which increased with increases in pH from 3.0 to 8.0. The signal corresponding to the species of the larger g-value increased markedly with an increase in glutathione concentration at neutral pH. EPR measurements at 77 degrees-K confirmed the stable production of Cr-V by glutathione. Characteristics of Cr-V generation by cysteine were quite different. The production of the Cr-V species was confirmed by a sharp single signal with a g-value of 1.984 to 1.987. The signal intensity corresponding to Cr-V generation did not change much with a change in pH from 3.0 to 6.0. Only a small signal was noted a pH 7.0. No signal was noted at pH 8.0. The lifetime of the Cr-V signal was shorter than that observed for the reduction with glutathione. The authors conclude that Cr-V may be stabilized in glutathione solution by its suitable redox potential and ligand structure."
1515997,Kiekens et al. 1988,Uptake and translocation of different forms of chromium by plants,Biosis copyright: biol abs. rrm abstract growth yield phytotoxicity,Uptake and translocation of different forms of chromium by plants Abs: Biosis copyright: biol abs. rrm abstract growth yield phytotoxicity
1515996,Kieber and  Heiz 1992,Indirect photoreduction of aqueous chromium-(VI),"BIOSIS COPYRIGHT: BIOL ABS. Field studies in a shallow estuary have revealed daytime decreases in the dissolved Cr(VI)r(III) ratio that correlate temporally with increases in the H2O2 concentration. Photolyzing water samples from the field site in silica flasks produces Cr(VI) loss and Cr(III) gain in essentially equimolar amounts. Reduction occurs neither in dark controls nor in prefiltered samples, indicating that both light and particles are essential. Field and laboratory results are consistent with reduction initiated by Fe(II), which has been generated photolytically from particulate ferric oxyhydroxides plus organic matter. Alternative mechanisms are discussed. At neutral pH, micromolar Fe(II) reduces nanomolar Cr(VI) in air-saturated solutions, despite O2 competition for the Fe(II). Because photoreduction of Fe appears to be common in nature and because the reaction of Fe(II) with Cr(VI) is extremely rapid, this reaction should be of general importance in surface waters. This natural proces","Indirect photoreduction of aqueous chromium-(VI) Abs: BIOSIS COPYRIGHT: BIOL ABS. Field studies in a shallow estuary have revealed daytime decreases in the dissolved Cr(VI)r(III) ratio that correlate temporally with increases in the H2O2 concentration. Photolyzing water samples from the field site in silica flasks produces Cr(VI) loss and Cr(III) gain in essentially equimolar amounts. Reduction occurs neither in dark controls nor in prefiltered samples, indicating that both light and particles are essential. Field and laboratory results are consistent with reduction initiated by Fe(II), which has been generated photolytically from particulate ferric oxyhydroxides plus organic matter. Alternative mechanisms are discussed. At neutral pH, micromolar Fe(II) reduces nanomolar Cr(VI) in air-saturated solutions, despite O2 competition for the Fe(II). Because photoreduction of Fe appears to be common in nature and because the reaction of Fe(II) with Cr(VI) is extremely rapid, this reaction should be of general importance in surface waters. This natural proces"
1515994,Khan et al. 1995,"Adsorption of chromium (III), chromium (VI) and silver (I) on bentonite","BIOSIS COPYRIGHT: BIOL ABS. The sorption of Cr(III), CR(VI) and Ag(I) from aqueous solutions on bentonite has been studied by a batch technique. Distribution coefficients (Kd) were determined for sorption systems as a function of contact time, pH, sorbent and sorbate concentration and temperature. Sorption data have been interpreted in terms of Freundlich, Langmuir and Dubinin-Raduskevich (D-R) equations. Thermodynamic parameters for the sorption systems have been determined at different temperatures. The sorption of Cr(III) and Ag(I) on bentonite is exothermic in nature while that of Cr(VI) is an endothermic process. The DELTAHê values for Cr(III), Cr(VI) and Ag(l) were -51.94 kJ/mol at 298 K, 5.619 kJ/mol at 293 K and -7.64 kJ/mol at 303 K respectively. The mean free energy of sorption, E, for Cr(VI) is 10 kJ/mol which shows that chromate ions from aqueous solutions at 10-5 to 10-3 M are predominantly sorbed on bentonite by an ion-exchange process. The sorption data for Cr(III) and Ag(I) do not MH - MATHEMATICS","Adsorption of chromium (III), chromium (VI) and silver (I) on bentonite Abs: BIOSIS COPYRIGHT: BIOL ABS. The sorption of Cr(III), CR(VI) and Ag(I) from aqueous solutions on bentonite has been studied by a batch technique. Distribution coefficients (Kd) were determined for sorption systems as a function of contact time, pH, sorbent and sorbate concentration and temperature. Sorption data have been interpreted in terms of Freundlich, Langmuir and Dubinin-Raduskevich (D-R) equations. Thermodynamic parameters for the sorption systems have been determined at different temperatures. The sorption of Cr(III) and Ag(I) on bentonite is exothermic in nature while that of Cr(VI) is an endothermic process. The DELTAHê values for Cr(III), Cr(VI) and Ag(l) were -51.94 kJ/mol at 298 K, 5.619 kJ/mol at 293 K and -7.64 kJ/mol at 303 K respectively. The mean free energy of sorption, E, for Cr(VI) is 10 kJ/mol which shows that chromate ions from aqueous solutions at 10-5 to 10-3 M are predominantly sorbed on bentonite by an ion-exchange process. The sorption data for Cr(III) and Ag(I) do not MH - MATHEMATICS"
1515993,Khalil 1992,Ionic valency of vanadium or chromium and the enzymatic activity in Streptomyces caeruleus,"BIOSIS COPYRIGHT: BIOL ABS. The results of this investigation establish the fact that addition of 10-6, 10-4 M chromium to the culture media, mostly stimulated the test intra- and extra-cellular enzymes of Streptomyces caeruleus. In most cases the hexavalent ion was more effective than the trivalent. Furthermore Cr6+ was more inhibitory to dry weight gain then Cr3+. In the meantime, V2+ was mostly suppressive (except on Ac-P and GPT), whereas V5+ was mostly stimulatory (endopeptidase being the exception). The dry weight gain was slightly reduced by the former vanadium form and severely suppressed by the latter form. Accordingly, it seems that the toxicity of these transitional elements was more apparent when supplemented in their high valency state, accompanied by increased enzyme activity. The latter could be attenuated by lowering the valency of the cationic form of the ions.","Ionic valency of vanadium or chromium and the enzymatic activity in Streptomyces caeruleus Abs: BIOSIS COPYRIGHT: BIOL ABS. The results of this investigation establish the fact that addition of 10-6, 10-4 M chromium to the culture media, mostly stimulated the test intra- and extra-cellular enzymes of Streptomyces caeruleus. In most cases the hexavalent ion was more effective than the trivalent. Furthermore Cr6+ was more inhibitory to dry weight gain then Cr3+. In the meantime, V2+ was mostly suppressive (except on Ac-P and GPT), whereas V5+ was mostly stimulatory (endopeptidase being the exception). The dry weight gain was slightly reduced by the former vanadium form and severely suppressed by the latter form. Accordingly, it seems that the toxicity of these transitional elements was more apparent when supplemented in their high valency state, accompanied by increased enzyme activity. The latter could be attenuated by lowering the valency of the cationic form of the ions."
1515992,Khalil 1991,"Valency (State of Oxidation), a Modulator for the Toxicity of Vanadium or Chromium to Streptomyces caeruleus","BIOSIS COPYRIGHT: BIOL ABS. The results show that the cationic form of either vanadium or chromium was less deleterious to dry weight gain by Streptomyces caeruleus than the anionic form. Whether cationic or anionic, chromium (at 10-4 10-6 M) was more toxic than vanadium. The control samples almost completely hydrolyzed the starch content of the prevailing medium. V(V)+ or Cr (VI)+ induced the same hydrolyzing capacity when administered at their highest concentration but V (IV)+ or Cr (III)+ were less effective. Per unit biomass, 10-4 M of the four salts substantially increased the amount of hydrolyzed starch, V (V)+ and Cr (VI)+ were equally higher in efficacy than V (IV)+ and Cr (III)+. V (IV)+ at 10-6-10-5 M, remarkably increased the percentage utilization of starch in biomass yield. The same range of concentration of V (V)+ seemed without effect whereas those of Cr (III)+ or Cr (VI)+ were almost equally suppressive. The antibiotic produced by S. caeruleus was highly potent against Erwinia carot","Valency (State of Oxidation), a Modulator for the Toxicity of Vanadium or Chromium to Streptomyces caeruleus Abs: BIOSIS COPYRIGHT: BIOL ABS. The results show that the cationic form of either vanadium or chromium was less deleterious to dry weight gain by Streptomyces caeruleus than the anionic form. Whether cationic or anionic, chromium (at 10-4 10-6 M) was more toxic than vanadium. The control samples almost completely hydrolyzed the starch content of the prevailing medium. V(V)+ or Cr (VI)+ induced the same hydrolyzing capacity when administered at their highest concentration but V (IV)+ or Cr (III)+ were less effective. Per unit biomass, 10-4 M of the four salts substantially increased the amount of hydrolyzed starch, V (V)+ and Cr (VI)+ were equally higher in efficacy than V (IV)+ and Cr (III)+. V (IV)+ at 10-6-10-5 M, remarkably increased the percentage utilization of starch in biomass yield. The same range of concentration of V (V)+ seemed without effect whereas those of Cr (III)+ or Cr (VI)+ were almost equally suppressive. The antibiotic produced by S. caeruleus was highly potent against Erwinia carot"
1515991,Key and  Woolrich 1965,"Dermatoses Investigation at Deena of Arlington, Arlington, Kentucky","An investigation was conducted on plating operations at Deena of Arlington, in Arlington, Kentucky, a lamp manufacturing company. The investigation was prompted by the occurrence of about ten cases of dermatitis over the past 5 years among plating shop workers. An environmental survey of the plating section of the facility identified several risks of dermatitis resulting from exposures to alkali and detergent cleaners, acid cleaners, copper and brass plating solutions, nickel plating solutions, and/or chromate conversion coatings. Housekeeping and personal hygienic measures were found to be poor. At the time of the evaluation one plater was found to have eczematous dermatitis. One of five plating workers patch tested demonstrated a positive reaction to hexavalent chromate and another had a questionable reaction to nickel (7440020). The authors recommend that the potential for dermatitis in this facility be reduced through the use of improved housekeeping, worker education about the use of protective equipment and proper personal hygiene, and requiring workers to wash with soap at breaks and the end of their workshifts.","Dermatoses Investigation at Deena of Arlington, Arlington, Kentucky Abs: An investigation was conducted on plating operations at Deena of Arlington, in Arlington, Kentucky, a lamp manufacturing company. The investigation was prompted by the occurrence of about ten cases of dermatitis over the past 5 years among plating shop workers. An environmental survey of the plating section of the facility identified several risks of dermatitis resulting from exposures to alkali and detergent cleaners, acid cleaners, copper and brass plating solutions, nickel plating solutions, and/or chromate conversion coatings. Housekeeping and personal hygienic measures were found to be poor. At the time of the evaluation one plater was found to have eczematous dermatitis. One of five plating workers patch tested demonstrated a positive reaction to hexavalent chromate and another had a questionable reaction to nickel (7440020). The authors recommend that the potential for dermatitis in this facility be reduced through the use of improved housekeeping, worker education about the use of protective equipment and proper personal hygiene, and requiring workers to wash with soap at breaks and the end of their workshifts."
1515988,Kaur and  Kaur 1996,Relative susceptibility of different life stages of channa punctatus and cyprinus carpio to nickel-chrome electroplating effluent,Biosis copyright: biol abs. rrm research article channa-punctatus cyprinus-carpio teleost fry relative susceptibility adult fingerling nickel-chrome electroplating effluent pollution toxicology toxicity industrial pollutant,Relative susceptibility of different life stages of channa punctatus and cyprinus carpio to nickel-chrome electroplating effluent Abs: Biosis copyright: biol abs. rrm research article channa-punctatus cyprinus-carpio teleost fry relative susceptibility adult fingerling nickel-chrome electroplating effluent pollution toxicology toxicity industrial pollutant
1515986,Kashiwaya et al. 1996,Laboratory study on dispersion prevention of dissolved sexivalent chromium in groundwater by cement-bentonite cut-off barriers,"BIOSIS COPYRIGHT: BIOL ABS. Laboratory permeability tests with soft groundwater contaminated by Cr6+ were carried out to develop measures to prevent dispersion of Cr6+ concentrate into a large amount of groundwater by providing cut-off barriers made from a mixture of blast furnace slag cement and sodium type bentonite. From these tests, it was necessary to maintain the permeability coefficient of 3sible after the barrier provision. Through a test in which MgCl2 of 270 mg and some amounts of Ca(OH)2 for pH adjustment were added to the permeating Cr6+ groundwater, it was found that for the pH to be adjusted within a range of 9.0 to 9.5 was an appropriate approach. Through the other test in which MgCl2 of 270 mg/L and some amounts of either poly-aluminium chloride (PAC) or Al2(SO4)3 were added to the permeating Cr6+ groundwater, it was also found that the addition of PAC brings a good result due to the reduction of permeability and no breakthrough of Cr6+ containing leachate. It was confirmed that t","Laboratory study on dispersion prevention of dissolved sexivalent chromium in groundwater by cement-bentonite cut-off barriers Abs: BIOSIS COPYRIGHT: BIOL ABS. Laboratory permeability tests with soft groundwater contaminated by Cr6+ were carried out to develop measures to prevent dispersion of Cr6+ concentrate into a large amount of groundwater by providing cut-off barriers made from a mixture of blast furnace slag cement and sodium type bentonite. From these tests, it was necessary to maintain the permeability coefficient of 3sible after the barrier provision. Through a test in which MgCl2 of 270 mg and some amounts of Ca(OH)2 for pH adjustment were added to the permeating Cr6+ groundwater, it was found that for the pH to be adjusted within a range of 9.0 to 9.5 was an appropriate approach. Through the other test in which MgCl2 of 270 mg/L and some amounts of either poly-aluminium chloride (PAC) or Al2(SO4)3 were added to the permeating Cr6+ groundwater, it was also found that the addition of PAC brings a good result due to the reduction of permeability and no breakthrough of Cr6+ containing leachate. It was confirmed that t"
1515985,Karlsen et al. 1996,Exposure to Hazardous Aerosols during Manual Metal Arc Welding on Nickel-Rich Alloys,"A study of hazardous metal fume exposures associated with manual metal arc (MMA) welding on nickel (7440020) containing alloys was conducted. Breathing zone samples were collected from three MMA welders during 5 consecutive work days and from one welder over 3 consecutive days while they welded on Inconel base material using Inconel electrodes. The Inconel alloy contained about 60% nickel and Inconel electrodes contained about 20% chromium (7440473). The samples were analyzed for total fume, nickel, iron (7439896), total chromium, hexavalent-chromium (18540299) (Cr+6), and manganese (7439965). The metal concentrations were determined by atomic absorption spectrometry. Cr+6 was determined by absorption spectrophotometry. The total fume concentrations in the samples varied from 0.8 to 41mg/m3. The arithmetic mean (AM) concentration was 4.8mg/m3. The AM breathing zone nickel, iron, total chromium, Cr+6, and manganese concentrations were 260, 340, 120, 21, and 14 micrograms per m3 (microg/m3), respectively. The nickel, iron, total chromium, Cr+6, and manganese concentrations were lognormally distributed. The AM nickel, iron, total chromium, Cr+6, and manganese contents of the fume were 38, 96, 16, 28, and 42microg/m3, respectively. The authors conclude that the metal composition of fume produced by MMA welding on Inconel (MMAnconel) welding appears to be different from the composition of fume produced by MMA on stainless steel (MMA/SS) welding. The nickel content of fume produced by MMA/Inconel welding is higher than that generated by MMA/SS welding and the iron, total chromium, and Cr+6 content of the fume is marginally less than that produced by MMA/SS welding.","Exposure to Hazardous Aerosols during Manual Metal Arc Welding on Nickel-Rich Alloys Abs: A study of hazardous metal fume exposures associated with manual metal arc (MMA) welding on nickel (7440020) containing alloys was conducted. Breathing zone samples were collected from three MMA welders during 5 consecutive work days and from one welder over 3 consecutive days while they welded on Inconel base material using Inconel electrodes. The Inconel alloy contained about 60% nickel and Inconel electrodes contained about 20% chromium (7440473). The samples were analyzed for total fume, nickel, iron (7439896), total chromium, hexavalent-chromium (18540299) (Cr+6), and manganese (7439965). The metal concentrations were determined by atomic absorption spectrometry. Cr+6 was determined by absorption spectrophotometry. The total fume concentrations in the samples varied from 0.8 to 41mg/m3. The arithmetic mean (AM) concentration was 4.8mg/m3. The AM breathing zone nickel, iron, total chromium, Cr+6, and manganese concentrations were 260, 340, 120, 21, and 14 micrograms per m3 (microg/m3), respectively. The nickel, iron, total chromium, Cr+6, and manganese concentrations were lognormally distributed. The AM nickel, iron, total chromium, Cr+6, and manganese contents of the fume were 38, 96, 16, 28, and 42microg/m3, respectively. The authors conclude that the metal composition of fume produced by MMA welding on Inconel (MMAnconel) welding appears to be different from the composition of fume produced by MMA on stainless steel (MMA/SS) welding. The nickel content of fume produced by MMA/Inconel welding is higher than that generated by MMA/SS welding and the iron, total chromium, and Cr+6 content of the fume is marginally less than that produced by MMA/SS welding."
1515983,Kanerva et al. 1996,"Occupational allergic contact dermatitis caused by 2,4,6-tris-(dimethylaminomethyl)phenol, and review of sensitizing epoxy resin hardeners","BIOSIS COPYRIGHT: BIOL ABS. Background. Epoxy resin compounds (ERC) include a large number of sensitizing chemicals such as epoxy resins (ER), hardeners (curing agents), and reactive diluents. Allergic contact dermatitis (ACD) caused by ERCs is often occupational. Materials and Methods. We report a patient, sensitized to a hardener of a two-component epoxy paint. Three conventional patch test sessions were performed to diagnose the causative chemical. We also review the literature on sensitizing epoxy-resin hardeners. Results. A 47-year-old nonatopic woman developed dermatitis from a two-component epoxy paint. Patch testing with epoxy resin was negative, but 2,4,6-tris(dimethylaminomethyl)phenol (tris-DMP), used in the paint hardener, induced an allergic patch test reaction. We also review briefly other epoxy hardeners that have caused allergic dermatitis, including; (1) aliphatic polyamines, e.g., ethylenediamine, diethylenetriamine, triethylenetetramine, 3-dimethylaminopropylamine, and trimethy","Occupational allergic contact dermatitis caused by 2,4,6-tris-(dimethylaminomethyl)phenol, and review of sensitizing epoxy resin hardeners Abs: BIOSIS COPYRIGHT: BIOL ABS. Background. Epoxy resin compounds (ERC) include a large number of sensitizing chemicals such as epoxy resins (ER), hardeners (curing agents), and reactive diluents. Allergic contact dermatitis (ACD) caused by ERCs is often occupational. Materials and Methods. We report a patient, sensitized to a hardener of a two-component epoxy paint. Three conventional patch test sessions were performed to diagnose the causative chemical. We also review the literature on sensitizing epoxy-resin hardeners. Results. A 47-year-old nonatopic woman developed dermatitis from a two-component epoxy paint. Patch testing with epoxy resin was negative, but 2,4,6-tris(dimethylaminomethyl)phenol (tris-DMP), used in the paint hardener, induced an allergic patch test reaction. We also review briefly other epoxy hardeners that have caused allergic dermatitis, including; (1) aliphatic polyamines, e.g., ethylenediamine, diethylenetriamine, triethylenetetramine, 3-dimethylaminopropylamine, and trimethy"
1515982,Kaminski 1988,Hazardous waste minimization part viii a hazardous waste minimization within the department of defense,Biosis copyright: biol abs. rrm review waste management metal plating painting explosives environmental pollutant pollution control,Hazardous waste minimization part viii a hazardous waste minimization within the department of defense Abs: Biosis copyright: biol abs. rrm review waste management metal plating painting explosives environmental pollutant pollution control
1515980,Kamburova 1993,Spectrophotometric determination of chromium with iodonitrotetrazolium chloride and tetrazolium violet,BIOSIS COPYRIGHT: BIOL ABS. The interaction of Iodonitrotetrazolium chloride and Tetrazolium Violet with chromium(VI) has been studied and the formation of ion-associates with a 1:1 composition in hydrochloric acid medium established. Extraction photometric methods for determination of chromium in steels and soils have been developed.,Spectrophotometric determination of chromium with iodonitrotetrazolium chloride and tetrazolium violet Abs: BIOSIS COPYRIGHT: BIOL ABS. The interaction of Iodonitrotetrazolium chloride and Tetrazolium Violet with chromium(VI) has been studied and the formation of ion-associates with a 1:1 composition in hydrochloric acid medium established. Extraction photometric methods for determination of chromium in steels and soils have been developed.
1515979,Kamburova 1993,Spectrophotometric determination of chromium VI with methylene blue,"BIOSIS COPYRIGHT: BIOL ABS. The interaction of Cr(VI) and the thiazine dye Methylene Blue has been examined. The ion-associate formed is extractable into 1,2-dichlorethane. The optimum conditions have been established, and values obtained for the conditional extraction constant K'ex, distribution constant K'D and association constant beta'. A sensitive and selective method for determination of microquantities of Cr(VI) in soils and alloys is suggested.","Spectrophotometric determination of chromium VI with methylene blue Abs: BIOSIS COPYRIGHT: BIOL ABS. The interaction of Cr(VI) and the thiazine dye Methylene Blue has been examined. The ion-associate formed is extractable into 1,2-dichlorethane. The optimum conditions have been established, and values obtained for the conditional extraction constant K'ex, distribution constant K'D and association constant beta'. A sensitive and selective method for determination of microquantities of Cr(VI) in soils and alloys is suggested."
1515976,Kaczynski and  Kleber 1993,Aqueous trivalent chromium photoproduction in natural waters,"BIOSIS COPYRIGHT: BIOL ABS. Field studies indicate Cr(III) is photochemically produced at two freshwater lakes in southeastern North Carolina (USA). Results of controlled photolysis experiments with marine and estuarine samples suggest this process may be common to many natural water systems. This photogeneration mechanism sheds new insight into the existence of the thermodynamically unstable Cr(III) ion in oxygenated surface waters. Sixty-eight water samples from seven water bodies in the southeastern United States (fresh, estuarine, and marine) displayed a range of total aqueous inorganic chromium from < 0.01 nM to 1.05 nM, with variable amounts of the trivalent and hexavalent species. These are the first Cr(III) and Cr(VI) values reported for all these aqueous systems and some of the first ever for nonmarine environments.","Aqueous trivalent chromium photoproduction in natural waters Abs: BIOSIS COPYRIGHT: BIOL ABS. Field studies indicate Cr(III) is photochemically produced at two freshwater lakes in southeastern North Carolina (USA). Results of controlled photolysis experiments with marine and estuarine samples suggest this process may be common to many natural water systems. This photogeneration mechanism sheds new insight into the existence of the thermodynamically unstable Cr(III) ion in oxygenated surface waters. Sixty-eight water samples from seven water bodies in the southeastern United States (fresh, estuarine, and marine) displayed a range of total aqueous inorganic chromium from < 0.01 nM to 1.05 nM, with variable amounts of the trivalent and hexavalent species. These are the first Cr(III) and Cr(VI) values reported for all these aqueous systems and some of the first ever for nonmarine environments."
1515975,Jung et al. 1995,Assessment of urease inhibition assays for measuring toxicity of environmental samples,"BIOSIS COPYRIGHT: BIOL ABS. We evaluated the potential of free and immobilized urease for assaying toxicity of environmental samples. Free urease was sensitive to heavy metals and insensitive to organic toxicants. Toxicity of industrial wastewaters and process water, as determined via free urease assay, was correlated with the heavy metal content of these samples. High background (blank) absorbance was encountered in samples containing ammonia. The background exceeded the linear range of the assay at ammonia nitrogen concentrations exceeding 8 mg/l. Immobilizing urease on glass beads was considered as a means of overcoming the problem of ammonia interference. Immobilized enzyme was unfortunately not sensitive to heavy metals. The potential of free urease for toxicity testing cannot be fully realized until a means of overcoming ammonia interference is developed.","Assessment of urease inhibition assays for measuring toxicity of environmental samples Abs: BIOSIS COPYRIGHT: BIOL ABS. We evaluated the potential of free and immobilized urease for assaying toxicity of environmental samples. Free urease was sensitive to heavy metals and insensitive to organic toxicants. Toxicity of industrial wastewaters and process water, as determined via free urease assay, was correlated with the heavy metal content of these samples. High background (blank) absorbance was encountered in samples containing ammonia. The background exceeded the linear range of the assay at ammonia nitrogen concentrations exceeding 8 mg/l. Immobilizing urease on glass beads was considered as a means of overcoming the problem of ammonia interference. Immobilized enzyme was unfortunately not sensitive to heavy metals. The potential of free urease for toxicity testing cannot be fully realized until a means of overcoming ammonia interference is developed."
1515974,Journe et al. 1999,Sunscreen sensitization: A 5-year study,"BIOSIS COPYRIGHT: BIOL ABS. The purpose of this study was to evaluate the prevalence of sunscreen contact allergy and/or contact photoallergy in 370 patients with suspected photodermatitis. Patch and photopatch tests were performed using the French Society of Photodermatology (SFPD) standard series. A total of 57 cases of contact allergy and/or photocontact allergy to sunscreens were diagnosed (15.4%). Amongst these, 27 reactions were related to oxybenzone and 14 to isopropyl dibenzoylmethane. These results, obtained from","Sunscreen sensitization: A 5-year study Abs: BIOSIS COPYRIGHT: BIOL ABS. The purpose of this study was to evaluate the prevalence of sunscreen contact allergy and/or contact photoallergy in 370 patients with suspected photodermatitis. Patch and photopatch tests were performed using the French Society of Photodermatology (SFPD) standard series. A total of 57 cases of contact allergy and/or photocontact allergy to sunscreens were diagnosed (15.4%). Amongst these, 27 reactions were related to oxybenzone and 14 to isopropyl dibenzoylmethane. These results, obtained from"
1515973,Jouany et al. 1982,Direct and integrated ecotoxicity of hexavalent chromium on 2 associated trophic levels: Chlorella vulgaris and Daphnia magna,"HEEP COPYRIGHT: BIOL ABS. The short (24-96 h) and medium (28 days) term toxicity of Cr6+ to C. vulgaris and D. magna was studied on both species in individual and mixed cultures. The toxic effects on Chlorella were evaluated by the following: Cr accumulation, where the enrichment ratio wasATP, used as an early indication of growth inhibition (CI50-24h: 470 mug/l); and algal growth after 96 h by optical density measurements (CI50-96h: 445 mug/l). The toxic effects on Daphnia were evaluated by studying the mortality rate of organisms immobilized after 24-h exposure and their ability to reproduce. The mortality of Daphnia (CI50-24h: 435 mug/l in medium without algae) was less in the presence of Chlorella whether the latter was contaminated with Cr or not. In mixed culture no cumulative effect was shown under medium-term exposure to Cr up to 28 days.","Direct and integrated ecotoxicity of hexavalent chromium on 2 associated trophic levels: Chlorella vulgaris and Daphnia magna Abs: HEEP COPYRIGHT: BIOL ABS. The short (24-96 h) and medium (28 days) term toxicity of Cr6+ to C. vulgaris and D. magna was studied on both species in individual and mixed cultures. The toxic effects on Chlorella were evaluated by the following: Cr accumulation, where the enrichment ratio wasATP, used as an early indication of growth inhibition (CI50-24h: 470 mug/l); and algal growth after 96 h by optical density measurements (CI50-96h: 445 mug/l). The toxic effects on Daphnia were evaluated by studying the mortality rate of organisms immobilized after 24-h exposure and their ability to reproduce. The mortality of Daphnia (CI50-24h: 435 mug/l in medium without algae) was less in the presence of Chlorella whether the latter was contaminated with Cr or not. In mixed culture no cumulative effect was shown under medium-term exposure to Cr up to 28 days."
1515969,Jooste and  Van Leeuwen 1994,Oxidation of nitrites in mine waters,Biosis copyright: biol abs. rrm research article nitrobacter nitrosomonas disinfection ammonia nitrification mining effluent,Oxidation of nitrites in mine waters Abs: Biosis copyright: biol abs. rrm research article nitrobacter nitrosomonas disinfection ammonia nitrification mining effluent
1515967,Johnson 1990,Rapid ion-exchange technique for the separation and preconcentration of chromium(VI) and chromium(III) in fresh waters,"BIOSIS COPYRIGHT: BIOL ABS. A technique for the separation and preconcentration of Cr(VI) and Cr(III) in fresh waters is presented. The analytical procedure involves the use of anion- and cation-exchange columns. The columns are eluted and the eluate is analysed for chromium using a graphite furnace atomic absorption spectrometer. The recovery of Cr(VI) and Cr(III) is 97.86 | 1.31% and 102.36 | 1.25% (95% confidence), respectively. The detection limits are 0.019 and 0.200 mug l-1 for 200 ml of sample (twice the standard deviation of eleven replicate blanks). The method is rapid and the need for minimum sample handling avoids contamination problems.","Rapid ion-exchange technique for the separation and preconcentration of chromium(VI) and chromium(III) in fresh waters Abs: BIOSIS COPYRIGHT: BIOL ABS. A technique for the separation and preconcentration of Cr(VI) and Cr(III) in fresh waters is presented. The analytical procedure involves the use of anion- and cation-exchange columns. The columns are eluted and the eluate is analysed for chromium using a graphite furnace atomic absorption spectrometer. The recovery of Cr(VI) and Cr(III) is 97.86 | 1.31% and 102.36 | 1.25% (95% confidence), respectively. The detection limits are 0.019 and 0.200 mug l-1 for 200 ml of sample (twice the standard deviation of eleven replicate blanks). The method is rapid and the need for minimum sample handling avoids contamination problems."
1515966,Johansson et al. 1988,Rabbit lung after inhalation of lithium chloride,Biosis copyright: biol abs. rrm inflammation metals,Rabbit lung after inhalation of lithium chloride Abs: Biosis copyright: biol abs. rrm inflammation metals
1515965,Jimenez et al. 1996,Automatic chromium (III)/(VI) preconcentration and speciation by flow injection-flame AAS,"BIOSIS COPYRIGHT: BIOL ABS. A sensitive, rapid flow injection flame AAS method for the simultaneous determination of Cr(III) and Cr(VI) following ion-exchange preconcentration is proposed. Chromium(III) is separated and preconcentrated on a cation-exchange resin, Amberlite IR-120, and Cr(VI) on Amberlite IRA-400. Preconcentration parameters (column site, eluent, loading and elution flow rate) were optimized, and the phase transfer, retention and enrichment factor for both species determined. The linear dynamic ranges achieved were 0-1000 mug for Cr(III) and 0-900 mug/L for Cr(VI), with a relative standard deviation of 4.4% and 7%, respectively. The detection limits obtained were 14.3 and 1.4 mug/L for Cr(III) and Cr(VI), respectively. The proposed method was applied with good results to the determination of both analytes in water samples from chrome-plating baths.","Automatic chromium (III)/(VI) preconcentration and speciation by flow injection-flame AAS Abs: BIOSIS COPYRIGHT: BIOL ABS. A sensitive, rapid flow injection flame AAS method for the simultaneous determination of Cr(III) and Cr(VI) following ion-exchange preconcentration is proposed. Chromium(III) is separated and preconcentrated on a cation-exchange resin, Amberlite IR-120, and Cr(VI) on Amberlite IRA-400. Preconcentration parameters (column site, eluent, loading and elution flow rate) were optimized, and the phase transfer, retention and enrichment factor for both species determined. The linear dynamic ranges achieved were 0-1000 mug for Cr(III) and 0-900 mug/L for Cr(VI), with a relative standard deviation of 4.4% and 7%, respectively. The detection limits obtained were 14.3 and 1.4 mug/L for Cr(III) and Cr(VI), respectively. The proposed method was applied with good results to the determination of both analytes in water samples from chrome-plating baths."
1515964,Jie et al. 1998,Determination of chromium in waste-water and cast iron samples by fluorescence quenching of rhodamine 6G,"BIOSIS COPYRIGHT: BIOL ABS. A new simple, selective and sensitive fluorescence quenching method was developed to determine chromium with rhodamine 6G. The method is based on the oxidation of rhodamine 6G by chromium(VI) in sulfuric acid solution. The linear calibration graph was obtained in the range 8-80 ng ml-1 chromium(VI). The detection limit is 0.8 ng ml-1. The method was applied successfully to the determination of chromium in waste water and cast iron samples.","Determination of chromium in waste-water and cast iron samples by fluorescence quenching of rhodamine 6G Abs: BIOSIS COPYRIGHT: BIOL ABS. A new simple, selective and sensitive fluorescence quenching method was developed to determine chromium with rhodamine 6G. The method is based on the oxidation of rhodamine 6G by chromium(VI) in sulfuric acid solution. The linear calibration graph was obtained in the range 8-80 ng ml-1 chromium(VI). The detection limit is 0.8 ng ml-1. The method was applied successfully to the determination of chromium in waste water and cast iron samples."
1515963,Jie et al. 1992,A fluorescence quenching method for the determination of chromium(VI) with L-tyrosine,BIOSIS COPYRIGHT: BIOL ABS. A fluorescence quenching method for the determination of Cr(VI) in aqueous solution is described. The fluorescence intensity of the system is linear over the range 5 to the determination of Cr(VI) in cast iron and waste water.,A fluorescence quenching method for the determination of chromium(VI) with L-tyrosine Abs: BIOSIS COPYRIGHT: BIOL ABS. A fluorescence quenching method for the determination of Cr(VI) in aqueous solution is described. The fluorescence intensity of the system is linear over the range 5 to the determination of Cr(VI) in cast iron and waste water.
1515962,Jensen and  Dietrich 1994,Measurements of pollutants chemical species,Biosis copyright: biol abs. rrm literature review pollution waste water treatment analysis methods immunoassay,Measurements of pollutants chemical species Abs: Biosis copyright: biol abs. rrm literature review pollution waste water treatment analysis methods immunoassay
1515961,Jen et al. 1993,Simultaneous determination of chromium(III) and chromium (VI) with reversed-phase ion-pair high-performance liquid chromatography,"A reversed-phase ion-pair high-performance liquid chromatographic method for the simultaneous determination of CrIII and CrVI in aqueous solution was developed. Chromium(III) was chelated with ethylenedi-aminetetraacetic acid (EDTA) prior to the analysis. A C8 column was used to separate the CrIII–EDTA complex from the CrVI ions using an eluent containing acetonitrile and tetrabutylammonium ion. The separated species were monitored at 242 nm using an ultraviolet (UV) detector. The factors affecting complex formation, the chromate stability and prospective interferences were investigated. The proposed method provides a simple analytical procedure for Cr speciation. The detection limits were 0.4 ng for CrIII and 1.6 ng for CrVI with a 20 µl injection. The relative standard deviations for CrIII and CrVI were 0.24 and 1.78%, respectively.","Simultaneous determination of chromium(III) and chromium (VI) with reversed-phase ion-pair high-performance liquid chromatography Abs: A reversed-phase ion-pair high-performance liquid chromatographic method for the simultaneous determination of CrIII and CrVI in aqueous solution was developed. Chromium(III) was chelated with ethylenedi-aminetetraacetic acid (EDTA) prior to the analysis. A C8 column was used to separate the CrIII–EDTA complex from the CrVI ions using an eluent containing acetonitrile and tetrabutylammonium ion. The separated species were monitored at 242 nm using an ultraviolet (UV) detector. The factors affecting complex formation, the chromate stability and prospective interferences were investigated. The proposed method provides a simple analytical procedure for Cr speciation. The detection limits were 0.4 ng for CrIII and 1.6 ng for CrVI with a 20 µl injection. The relative standard deviations for CrIII and CrVI were 0.24 and 1.78%, respectively."
1515960,Jaworska et al. 1996,Effect of metal ions under laboratory conditions on the entomopathogenic Steinernema carpocapsae (Rhabditida: Steinernematidae),"BIOSIS COPYRIGHT: BIOL ABS. The effects of sixteen metal ions: Al, Cd, Co(II), Cr(III), Cr(VI), Cu(II), Fe(III), Li, Mg, Mn(II), Mo(VI), Ni(II), Pb(II), Se(IV), V(V), and Zn on the mortality and infectivity of Steinernema carpocapsae were observed in 96 hour laboratory tests. All ions except Cu(II), Pb(II), and Zn even at naturally unrealistic concentrations did not cause the mortality of S. carpocapsae. However, such treatment lowered infectivity of nematodes with respect to wax moth caterpillars, Galleria mellonella.","Effect of metal ions under laboratory conditions on the entomopathogenic Steinernema carpocapsae (Rhabditida: Steinernematidae) Abs: BIOSIS COPYRIGHT: BIOL ABS. The effects of sixteen metal ions: Al, Cd, Co(II), Cr(III), Cr(VI), Cu(II), Fe(III), Li, Mg, Mn(II), Mo(VI), Ni(II), Pb(II), Se(IV), V(V), and Zn on the mortality and infectivity of Steinernema carpocapsae were observed in 96 hour laboratory tests. All ions except Cu(II), Pb(II), and Zn even at naturally unrealistic concentrations did not cause the mortality of S. carpocapsae. However, such treatment lowered infectivity of nematodes with respect to wax moth caterpillars, Galleria mellonella."
1515959,Jaworska et al. 1997,Effect of metal ions on the entomopathogenic nematode Heterorhabditis bacteriophora Poinar (Nematoda: Heterorhabditidae) under laboratory conditions,"BIOSIS COPYRIGHT: BIOL ABS. The effect of sixteen metal ions: Al, Cd, Co(II), Cr(III), Cr(VI), Cu(II), Fe(III), Li, Mg, Mn(II), Mo(VI), Ni(II), Pb(II), Se(IV), V(V), and Zn on the mortality and infectivity of Heterorhabditis bacteriophora were observed over a 96 hr period. All ions except Pb(II) even at naturally unrealistic concentrations did not cause the mortality of the nematodes. A weak vitalizing effect could eventually be observed with Mn(II), Mg, Fe(III) and Ni(II) (Table 1). However, such treatment generally lowered infectivity of the nematodes with respect to wax moth caterpillars, Galleria mellonella. This effect was particularly significant with Ni(II) and Pb(II).","Effect of metal ions on the entomopathogenic nematode Heterorhabditis bacteriophora Poinar (Nematoda: Heterorhabditidae) under laboratory conditions Abs: BIOSIS COPYRIGHT: BIOL ABS. The effect of sixteen metal ions: Al, Cd, Co(II), Cr(III), Cr(VI), Cu(II), Fe(III), Li, Mg, Mn(II), Mo(VI), Ni(II), Pb(II), Se(IV), V(V), and Zn on the mortality and infectivity of Heterorhabditis bacteriophora were observed over a 96 hr period. All ions except Pb(II) even at naturally unrealistic concentrations did not cause the mortality of the nematodes. A weak vitalizing effect could eventually be observed with Mn(II), Mg, Fe(III) and Ni(II) (Table 1). However, such treatment generally lowered infectivity of the nematodes with respect to wax moth caterpillars, Galleria mellonella. This effect was particularly significant with Ni(II) and Pb(II)."
1515958,Jaworska et al. 1997,Metal-metal interactions in biological systems. Part V. Steinernema carpocapsae (Steinernematidae) and Heterorhabditis bacteriophora (Heterorhabditidae) entomopathogenic nematodes,"BIOSIS COPYRIGHT: BIOL ABS. In spite of a lack of acute toxicity of single metal ions, in 96 hour laboratory tests there was a long term toxicity against S. carpocapsae and H. bacteriophora nematodes. The 96 hour laboratory tests were carried out in order to prove possible synergistic and antagonistic interactions between pairs of metal ions. Thus, the pairs of ions were arranged from each of Al, Cd, Co(II), Cr(III), Cr(VI), Cu(II), Fe(III), Li, Mo(VI), Ni(II), Se(IV), V(V) and Zn on one side and Mn(II) and Mg on the other. Mn(II) and Mg ions considerably reduced the nematode mortality and increased their infectivity against Galleria mellonella caterpillars.","Metal-metal interactions in biological systems. Part V. Steinernema carpocapsae (Steinernematidae) and Heterorhabditis bacteriophora (Heterorhabditidae) entomopathogenic nematodes Abs: BIOSIS COPYRIGHT: BIOL ABS. In spite of a lack of acute toxicity of single metal ions, in 96 hour laboratory tests there was a long term toxicity against S. carpocapsae and H. bacteriophora nematodes. The 96 hour laboratory tests were carried out in order to prove possible synergistic and antagonistic interactions between pairs of metal ions. Thus, the pairs of ions were arranged from each of Al, Cd, Co(II), Cr(III), Cr(VI), Cu(II), Fe(III), Li, Mo(VI), Ni(II), Se(IV), V(V) and Zn on one side and Mn(II) and Mg on the other. Mn(II) and Mg ions considerably reduced the nematode mortality and increased their infectivity against Galleria mellonella caterpillars."
1515957,Jasuja et al. 1997,Removal of Cr(VI) from wastewater by Abelsmoschus esculentus,"BIOSIS COPYRIGHT: BIOL ABS. Removal of chromium(VI) from aqueous waste was investigated using adsorbent from Ablesmoschus esculentus (Lady Finger plant). The effects of pH, Cr(VI) concentration, adsorbent dose and contact time were studied in batch experiments. The removal was in general most effective at low pH values. Favourable conditions are an equilibrium time of 6 hours and an adsorbent dose of 10 gm/litre.","Removal of Cr(VI) from wastewater by Abelsmoschus esculentus Abs: BIOSIS COPYRIGHT: BIOL ABS. Removal of chromium(VI) from aqueous waste was investigated using adsorbent from Ablesmoschus esculentus (Lady Finger plant). The effects of pH, Cr(VI) concentration, adsorbent dose and contact time were studied in batch experiments. The removal was in general most effective at low pH values. Favourable conditions are an equilibrium time of 6 hours and an adsorbent dose of 10 gm/litre."
1515956,Janos 1992,Ion-chromatographic determination of chromium(VI),BIOSIS COPYRIGHT: BIOL ABS. A simple ion-chromatographic method has been developed for the selective determination of chromium (VI) using UV-photometric detection. The anion exchanger was based on a matrix of 12-hydroxyethyl-methacrylate copolymer; the mobile phase consisted of phosphate buffer and sodium perchlorate. The relative standard deviation was 2.26%. Application was made to waste waters of the metallurgical industry.,Ion-chromatographic determination of chromium(VI) Abs: BIOSIS COPYRIGHT: BIOL ABS. A simple ion-chromatographic method has been developed for the selective determination of chromium (VI) using UV-photometric detection. The anion exchanger was based on a matrix of 12-hydroxyethyl-methacrylate copolymer; the mobile phase consisted of phosphate buffer and sodium perchlorate. The relative standard deviation was 2.26%. Application was made to waste waters of the metallurgical industry.
1515954,Itoh et al. 1995,Mechanism of chromium(VI) toxicity in Escherichia coli: Is hydrogen peroxide essential in Cr(VI) toxicity?,"To investigate the role of hydrogen peroxide in Cr(VI) toxicity in vivo toward bacterial cells, we examined the effect of Cr(VI), hydrogen peroxide, sodium azide, and mannitol on the viability of Escherichia coli. Bacterial cells were incubated for 1 h with shaking in the presence of Cr(VI), hydrogen peroxide, sodium azide as catalase inhibitor, and/or mannitol as radical scavenger. The colony-forming ability and double-strand DNA degradation were examined. The viability assays revealed that Cr(VI) toxicity depended on hydroxyl radicals generated in the reaction involving hydrogen peroxide and chromium. Moreover, incubation of E. coli cells with 10 mM Cr(VI) and 3 mM hydrogen peroxide caused the degradation of double-strand DNA in vivo, which was suppressed by the addition of mannitol. These results indicated that hydroxyl radicals generated in the incubation degraded DNA of E. coli cells, resulting in cell death. In the absence of added hydrogen peroxide, the intracell","Mechanism of chromium(VI) toxicity in Escherichia coli: Is hydrogen peroxide essential in Cr(VI) toxicity? Abs: To investigate the role of hydrogen peroxide in Cr(VI) toxicity in vivo toward bacterial cells, we examined the effect of Cr(VI), hydrogen peroxide, sodium azide, and mannitol on the viability of Escherichia coli. Bacterial cells were incubated for 1 h with shaking in the presence of Cr(VI), hydrogen peroxide, sodium azide as catalase inhibitor, and/or mannitol as radical scavenger. The colony-forming ability and double-strand DNA degradation were examined. The viability assays revealed that Cr(VI) toxicity depended on hydroxyl radicals generated in the reaction involving hydrogen peroxide and chromium. Moreover, incubation of E. coli cells with 10 mM Cr(VI) and 3 mM hydrogen peroxide caused the degradation of double-strand DNA in vivo, which was suppressed by the addition of mannitol. These results indicated that hydroxyl radicals generated in the incubation degraded DNA of E. coli cells, resulting in cell death. In the absence of added hydrogen peroxide, the intracell"
1515951,Ingle and  Sule 1992,Determination of chromium-iii and chromium-vi with a two-column ion-exhange system,Biosis copyright: biol abs. rrm abstract environmental sampling environmental toxicity spectrophotometry analytical method,Determination of chromium-iii and chromium-vi with a two-column ion-exhange system Abs: Biosis copyright: biol abs. rrm abstract environmental sampling environmental toxicity spectrophotometry analytical method
1515949,Imai and  Gloyna 1990,Effects of pH and oxidation state of chromium on the behavior of chromium in the activated sludge process,"BIOSIS COPYRIGHT: BIOL ABS. The behavior of chromium (Cr) in the activated sludge process (ASP) was evaluated in laboratory-scale, fill-and-draw activated sludge experiments. Both pH and the oxidation state of chromium were confirmed as critical parameters in the ASP for evaluating the behavior of chromium. More than 55% of chromium was removed when trivalent chromium (Cr(III)) was introduced into the influent while less than 60% was removed when hexavalent chromium (Cr(VI)) was added over a pH range from 5 to 9. As pH was increased, the removal increased when Cr(III) was introduced but the reverse occurred with Cr(VI). Introduction of Cr(VI) into the influent resulted in less than 80% of chromium associated with solids; however, with Cr(III), more than 90% of chromium was bound with solids. These results suggest that the ASP is capable of controlling the transport of Cr(III) to the environment but such is not case for Cr(VI). Theoretical consideration based on thermodynamics predicted that no red","Effects of pH and oxidation state of chromium on the behavior of chromium in the activated sludge process Abs: BIOSIS COPYRIGHT: BIOL ABS. The behavior of chromium (Cr) in the activated sludge process (ASP) was evaluated in laboratory-scale, fill-and-draw activated sludge experiments. Both pH and the oxidation state of chromium were confirmed as critical parameters in the ASP for evaluating the behavior of chromium. More than 55% of chromium was removed when trivalent chromium (Cr(III)) was introduced into the influent while less than 60% was removed when hexavalent chromium (Cr(VI)) was added over a pH range from 5 to 9. As pH was increased, the removal increased when Cr(III) was introduced but the reverse occurred with Cr(VI). Introduction of Cr(VI) into the influent resulted in less than 80% of chromium associated with solids; however, with Cr(III), more than 90% of chromium was bound with solids. These results suggest that the ASP is capable of controlling the transport of Cr(III) to the environment but such is not case for Cr(VI). Theoretical consideration based on thermodynamics predicted that no red"
1515948,Huybrechts et al. 1992,Chromium iii binding and chromium vi reduction in bacteria isolated from soil,Biosis copyright: biol abs. rrm abstract pseudomonas moraxella corynebacterium competition salts cations,Chromium iii binding and chromium vi reduction in bacteria isolated from soil Abs: Biosis copyright: biol abs. rrm abstract pseudomonas moraxella corynebacterium competition salts cations
1515947,Hughes and  Hampl 1986,Developments in Push-Pull Ventilation,"Recent developments in push/pull ventilation were discussed. The nature of push/pull ventilation was described. Push/pull ventilation involved using jets or curtains of air in conjunction with local exhaust ventilation to direct the flow of ambient workplace air. The net effect was to enhance the effectiveness of normal local exhaust ventilation. Research studies in the area of push/pull ventilation conducted by NIOSH during the last 4 years were summarized. A laboratory study of the effect of push/pull ventilation on emissions from a mock plating tank utilizing a heated water alcohol bath was conducted. Push/pull ventilation achieved capture efficiencies of 90 to 95 percent and reduced the pull flow necessary to achieve this flow to less than 50 percent of that normally required for normal local exhaust ventilation. In field testing, an average air level of 0.032mg/m3 chromium(VI) (18540299) was achieved for a chrome plating ventilation system. Laboratory and field studies of foundry air carbon arc gouging and torch cutting operations showed that push/pull ventilation reduced exposures to metal fumes to less than 0.80mg/m3 for carbon arc gouging and to 1.65 to 6.11mg/m3 for torch cutting. Field studies of rubber and plastic milling operations showed that push/pull ventilation using an air curtain reduced mill emissions by over 50 percent with a concomitant 33 percent reduction in exhaust airflow. The air curtain also reduced heat stress created by the hot plastic. The authors conclude that push/pull ventilation can provide cost savings and permit emission control that could not be achieved by local exhaust ventilation alone.","Developments in Push-Pull Ventilation Abs: Recent developments in push/pull ventilation were discussed. The nature of push/pull ventilation was described. Push/pull ventilation involved using jets or curtains of air in conjunction with local exhaust ventilation to direct the flow of ambient workplace air. The net effect was to enhance the effectiveness of normal local exhaust ventilation. Research studies in the area of push/pull ventilation conducted by NIOSH during the last 4 years were summarized. A laboratory study of the effect of push/pull ventilation on emissions from a mock plating tank utilizing a heated water alcohol bath was conducted. Push/pull ventilation achieved capture efficiencies of 90 to 95 percent and reduced the pull flow necessary to achieve this flow to less than 50 percent of that normally required for normal local exhaust ventilation. In field testing, an average air level of 0.032mg/m3 chromium(VI) (18540299) was achieved for a chrome plating ventilation system. Laboratory and field studies of foundry air carbon arc gouging and torch cutting operations showed that push/pull ventilation reduced exposures to metal fumes to less than 0.80mg/m3 for carbon arc gouging and to 1.65 to 6.11mg/m3 for torch cutting. Field studies of rubber and plastic milling operations showed that push/pull ventilation using an air curtain reduced mill emissions by over 50 percent with a concomitant 33 percent reduction in exhaust airflow. The air curtain also reduced heat stress created by the hot plastic. The authors conclude that push/pull ventilation can provide cost savings and permit emission control that could not be achieved by local exhaust ventilation alone."
1515946,Hug et al. 1997,Iron(III) catalyzed photochemical reduction of chromium(VI) by oxalate and citrate in aqueous solutions,"BIOSIS COPYRIGHT: BIOL ABS. Cr(VI) reduction in soil solution, wastewater, and natural waters is poorly understood in complex systems containing Fe(II,III) and dissolved organic C, especially when influenced by sunlight. The Fe(II,III)-mediated photochemical reduction of Cr(VI) was investigated in a laboratory study with 5-200 muM Cr(VI), 25-1300 muM oxalate or citrate, 0.13-6.7 muM Fe(III), 10 mM KCl, pH 3-7, and a xenon light source (720 W/m2 between 300 and 800 nm) at 25 ê C. In situ UV-VIS multicomponent analysis avoided addition of interfering reagents. At higher (Cr(VI)), photochemical Cr(VI) reduction was zero order in (Cr), with quantum yields (relative to light absorption by Fe(III)-oxalate) of up to 0.53. Over 95% Cr(IV) reduction was observed within 20-40 min in 5-cm cells. At lower (Cr(VI)), the reaction order became complex due to slow reaction of Fe(II) with Cr(VI) compared to photochemical Fe(II) production. The thermal reaction of Cr(VI) with Fe(II) at pH 5 was measured and describe","Iron(III) catalyzed photochemical reduction of chromium(VI) by oxalate and citrate in aqueous solutions Abs: BIOSIS COPYRIGHT: BIOL ABS. Cr(VI) reduction in soil solution, wastewater, and natural waters is poorly understood in complex systems containing Fe(II,III) and dissolved organic C, especially when influenced by sunlight. The Fe(II,III)-mediated photochemical reduction of Cr(VI) was investigated in a laboratory study with 5-200 muM Cr(VI), 25-1300 muM oxalate or citrate, 0.13-6.7 muM Fe(III), 10 mM KCl, pH 3-7, and a xenon light source (720 W/m2 between 300 and 800 nm) at 25 ê C. In situ UV-VIS multicomponent analysis avoided addition of interfering reagents. At higher (Cr(VI)), photochemical Cr(VI) reduction was zero order in (Cr), with quantum yields (relative to light absorption by Fe(III)-oxalate) of up to 0.53. Over 95% Cr(IV) reduction was observed within 20-40 min in 5-cm cells. At lower (Cr(VI)), the reaction order became complex due to slow reaction of Fe(II) with Cr(VI) compared to photochemical Fe(II) production. The thermal reaction of Cr(VI) with Fe(II) at pH 5 was measured and describe"
1515945,Huang and  Koseoglu 1993,Separation of heavy metals from industrial waste streams by membrane separation technology,Biosis copyright: biol abs. rrm meeting paper toxic pollutants donnan dialysis membrane bioreactor,Separation of heavy metals from industrial waste streams by membrane separation technology Abs: Biosis copyright: biol abs. rrm meeting paper toxic pollutants donnan dialysis membrane bioreactor
1515944,Huang et al. 1998,Extraction equilibria of chromium(VI) from sulfuric acid solutions with tri-n-octylphosphine oxide,"BIOSIS COPYRIGHT: BIOL ABS. The extraction equilibria of chromium(VI) from sulfuric acid solutions with tri-n-octylphosphine oxide (TOPO) dissolved in kerosene at 25ê C have been studied. The possible complexes of chromium(VI) with TOPO in organic phase and extraction constants were determined by best fitting the distribution coefficient expression of Cr(VI) with experimental data using the Rosenbrock method. The extraction reactions, including the equilibria among seven species in aqueous phase (H2CrO4, HCrO4-, HCr2O7-, Cr2O72-, CrSO72-, HSO4- and SO42-) and five possible complexes in organic phase (H2CrO4Cr2O72cid concentration on the fraction of extracted complexes and on the distribution coefficients of Cr(VI) is discussed. This result was helpful for the clarification of the extraction reactions of Cr(VI).","Extraction equilibria of chromium(VI) from sulfuric acid solutions with tri-n-octylphosphine oxide Abs: BIOSIS COPYRIGHT: BIOL ABS. The extraction equilibria of chromium(VI) from sulfuric acid solutions with tri-n-octylphosphine oxide (TOPO) dissolved in kerosene at 25ê C have been studied. The possible complexes of chromium(VI) with TOPO in organic phase and extraction constants were determined by best fitting the distribution coefficient expression of Cr(VI) with experimental data using the Rosenbrock method. The extraction reactions, including the equilibria among seven species in aqueous phase (H2CrO4, HCrO4-, HCr2O7-, Cr2O72-, CrSO72-, HSO4- and SO42-) and five possible complexes in organic phase (H2CrO4Cr2O72cid concentration on the fraction of extracted complexes and on the distribution coefficients of Cr(VI) is discussed. This result was helpful for the clarification of the extraction reactions of Cr(VI)."
1515941,Hsia et al. 1992,Interaction of chromium-vi with amorphous iron oxide adsorption density and surface charge,Biosis copyright: biol abs. rrm hazardous waste management pollution control heavy metals temperature nitrogen atmosphere,Interaction of chromium-vi with amorphous iron oxide adsorption density and surface charge Abs: Biosis copyright: biol abs. rrm hazardous waste management pollution control heavy metals temperature nitrogen atmosphere
1515916,Horvath et al. 1994,Determination of trace metals and speciation of chromium ions atmospheric precipitation by icp-aes and gfaas,Biosis copyright: biol abs. rrm research article trivalent chromium tetravalent chromium iminodiacetic acid ethylcellulose graphite furnace atomic absorption spectrometry inductively coupled plasma atomic emission spectrometry analytical method,Determination of trace metals and speciation of chromium ions atmospheric precipitation by icp-aes and gfaas Abs: Biosis copyright: biol abs. rrm research article trivalent chromium tetravalent chromium iminodiacetic acid ethylcellulose graphite furnace atomic absorption spectrometry inductively coupled plasma atomic emission spectrometry analytical method
1515915,Horowitz and  Finley 1993,Using Human Sweat to Extract Chromium from Chromite Ore Processing Residue: Applications to Setting Health-Based Cleanup Levels,"The ability of human sweat to extract chromium (7440473) from chromite ore processing residue (COPR) was investigated to assess the risk of allergic contact dermatitis resulting from contact with COPR, which had been used to fill in low lying areas in Hudson County, New Jersey. Samples of COPR material containing 16, 136, and 1,240 parts per million (ppm) hexavalent chromium (Cr+6) and 930 and 6,660ppm total chromium (Crtot), Cr+6 plus trivalent chromium (Cr+3), were sieved to obtain a uniform particle size of 500 micrometers. They were extracted with sweat collected from seven male volunteers at sweat ratios (dilution ratios) of 20:1 or 5:1 for 12 hours at 30 degrees-C. The 20:1 and 5:1 dilution ratios were chosen to simulate perspiration conditions associated with moderate and light physical activity, respectively. No Cr+6 could be detected in extracts of the 16ppm Cr+6 containing COPR sample or following extraction of the 136ppm COPR sample with sweat with the 20:1 dilution ratio. Extraction of the 136ppm Cr+6 containing COPR sample with sweat having the 5:1 dilution ratio removed 0.09% of the Cr+6. Following treatment of the 1,240ppm Cr+6 containing COPR sample, the extracts with dilution ratios of 5:1 and 20:1 contained 0.133 and 0.040ppm Cr+6. This represented removal efficiencies of 0.05 and 0.06%, respectively. No chromium was removed by extraction of the 932ppm Crtot containing sample with the 20:1 sweat dilution. Following extraction of this sample with the 5:1 sweat dilution, the extract contained 0.15ppm chromium. This indicated that 0.06% of the Crtot content had been removed. Extraction of the 6,660ppm Crtot containing COPR sample with the 5:1 and 20:1 sweat dilutions removed 0.11 to 0.16 and 0.23 to 0.25% of the chromium, respectively. The authors conclude that environmental contact with this particular COPR is unlikely to cause allergic contact dermatitis since the concentrations of solubilized Cr+6 or Cr+3 required to cause allergic contact dermatitis have been estimated to be 10 to 54ppm or 10,000 to 54,000ppm, respectively.","Using Human Sweat to Extract Chromium from Chromite Ore Processing Residue: Applications to Setting Health-Based Cleanup Levels Abs: The ability of human sweat to extract chromium (7440473) from chromite ore processing residue (COPR) was investigated to assess the risk of allergic contact dermatitis resulting from contact with COPR, which had been used to fill in low lying areas in Hudson County, New Jersey. Samples of COPR material containing 16, 136, and 1,240 parts per million (ppm) hexavalent chromium (Cr+6) and 930 and 6,660ppm total chromium (Crtot), Cr+6 plus trivalent chromium (Cr+3), were sieved to obtain a uniform particle size of 500 micrometers. They were extracted with sweat collected from seven male volunteers at sweat ratios (dilution ratios) of 20:1 or 5:1 for 12 hours at 30 degrees-C. The 20:1 and 5:1 dilution ratios were chosen to simulate perspiration conditions associated with moderate and light physical activity, respectively. No Cr+6 could be detected in extracts of the 16ppm Cr+6 containing COPR sample or following extraction of the 136ppm COPR sample with sweat with the 20:1 dilution ratio. Extraction of the 136ppm Cr+6 containing COPR sample with sweat having the 5:1 dilution ratio removed 0.09% of the Cr+6. Following treatment of the 1,240ppm Cr+6 containing COPR sample, the extracts with dilution ratios of 5:1 and 20:1 contained 0.133 and 0.040ppm Cr+6. This represented removal efficiencies of 0.05 and 0.06%, respectively. No chromium was removed by extraction of the 932ppm Crtot containing sample with the 20:1 sweat dilution. Following extraction of this sample with the 5:1 sweat dilution, the extract contained 0.15ppm chromium. This indicated that 0.06% of the Crtot content had been removed. Extraction of the 6,660ppm Crtot containing COPR sample with the 5:1 and 20:1 sweat dilutions removed 0.11 to 0.16 and 0.23 to 0.25% of the chromium, respectively. The authors conclude that environmental contact with this particular COPR is unlikely to cause allergic contact dermatitis since the concentrations of solubilized Cr+6 or Cr+3 required to cause allergic contact dermatitis have been estimated to be 10 to 54ppm or 10,000 to 54,000ppm, respectively."
1515913,Horng et al. 1987,Evaluating Electro-Kinetics as a Remedial Action Technique,"Laboratory electrokinetic experiments were carried out on samples of contaminated soil taken from the United Chrome Products (UCP) Superfund site near Corvallis, Oregon, to assess the use of electrokinetics for contaminant removal. The most important contaminant in these samples was hexavalent chromium (18540299) in anionic form. Tests were run in a specially designed electroosmotic odometer with electrode assemblies at both ends. Test variables in runs using hydraulic leaching alone or in combination with electrokinetic treatment included hydraulic gradient, induced flow velocity, total flow velocity, total liquid flow, strength and direction of the electric field, treatment time interval, and total electric current. The combination of hydraulic leaching and electrokinetic treatment accelerated chromium removal compared to hydraulic leaching alone. Increased and decreased chromium leaching was observed when the effluent was collected at the anode and at the cathode, respectively. The optimal volume ratio of fluid collected to soil column was 0.3 to 0.5. No advantage was found in reversals of either the electrical field or hydraulic flow during the combined treatment. The authors conclude that electrokinetic treatment may have application to contaminated soils at the UCP site.","Evaluating Electro-Kinetics as a Remedial Action Technique Abs: Laboratory electrokinetic experiments were carried out on samples of contaminated soil taken from the United Chrome Products (UCP) Superfund site near Corvallis, Oregon, to assess the use of electrokinetics for contaminant removal. The most important contaminant in these samples was hexavalent chromium (18540299) in anionic form. Tests were run in a specially designed electroosmotic odometer with electrode assemblies at both ends. Test variables in runs using hydraulic leaching alone or in combination with electrokinetic treatment included hydraulic gradient, induced flow velocity, total flow velocity, total liquid flow, strength and direction of the electric field, treatment time interval, and total electric current. The combination of hydraulic leaching and electrokinetic treatment accelerated chromium removal compared to hydraulic leaching alone. Increased and decreased chromium leaching was observed when the effluent was collected at the anode and at the cathode, respectively. The optimal volume ratio of fluid collected to soil column was 0.3 to 0.5. No advantage was found in reversals of either the electrical field or hydraulic flow during the combined treatment. The authors conclude that electrokinetic treatment may have application to contaminated soils at the UCP site."
1515911,Horlick 1996,Investigations into chromium speciation by electrospray mass spectrometry. AU - STEWART II,"BIOSIS COPYRIGHT: BIOL ABS. Chromium is an element whose toxicity is oxidation state dependent. Chromium(VI) is considered toxic to humans whereas CrIII is considered to be an essential nutrient. It therefore becomes important to be able to distinguish between the two oxidation states in solution. In this study it is shown that electrospray mass spectrometry (ESMS) has the potential to provide useful information on chromium species in solution samples. The various solution forms of both oxidation states may be observed directly and are presented. In addition, other more uncommon species of both oxidation states such as polymeric CrIII and the polyanion trichromate are discussed. Finally, the ability of ESMS to monitor other aspects of the solution chemistry of both chromium oxidation states is explored.","Investigations into chromium speciation by electrospray mass spectrometry. AU - STEWART II Abs: BIOSIS COPYRIGHT: BIOL ABS. Chromium is an element whose toxicity is oxidation state dependent. Chromium(VI) is considered toxic to humans whereas CrIII is considered to be an essential nutrient. It therefore becomes important to be able to distinguish between the two oxidation states in solution. In this study it is shown that electrospray mass spectrometry (ESMS) has the potential to provide useful information on chromium species in solution samples. The various solution forms of both oxidation states may be observed directly and are presented. In addition, other more uncommon species of both oxidation states such as polymeric CrIII and the polyanion trichromate are discussed. Finally, the ability of ESMS to monitor other aspects of the solution chemistry of both chromium oxidation states is explored."
1515910,Horitsu et al. 1987,Enzymatic reduction of hexavalent chromium by hexavalent chromium tolerant pseudomonas-ambigua g-1,Biosis copyright: biol abs. rrm nutrition nadh nadph mutants enzyme activation protection,Enzymatic reduction of hexavalent chromium by hexavalent chromium tolerant pseudomonas-ambigua g-1 Abs: Biosis copyright: biol abs. rrm nutrition nadh nadph mutants enzyme activation protection
1515875,Hong and  Sewell 1998,Crv1 bioreduction in the cr-contaminated subsurface environment,Biosis copyright: biol abs. rrm meeting abstract pollution toxicology chromium vi heavy metal pollutant toxin bioreduction subsurface environmental pollution subterranean ecology,Crv1 bioreduction in the cr-contaminated subsurface environment Abs: Biosis copyright: biol abs. rrm meeting abstract pollution toxicology chromium vi heavy metal pollutant toxin bioreduction subsurface environmental pollution subterranean ecology
1515873,Hofner et al. 1987,Use of laboratory cultures of some algae to predict heavy metal toxicity i. the role of some heavy metals in the growth pigmentation carbohydrate and protein synthesis in chlorella-fusca and spirulina-maxima,Biosis copyright: biol abs. rrm industrial pollution chlorophyll content growth arrest dry weight gain inhibition hexavalent chromium zinc,Use of laboratory cultures of some algae to predict heavy metal toxicity i. the role of some heavy metals in the growth pigmentation carbohydrate and protein synthesis in chlorella-fusca and spirulina-maxima Abs: Biosis copyright: biol abs. rrm industrial pollution chlorophyll content growth arrest dry weight gain inhibition hexavalent chromium zinc
1515864,Hiraide and  Mizuike 1989,Separation and determination of chromium(VI) anions and chromium(III) associated with negatively charged colloids in river water by sorption on DEAE-Sephadex A-25,"BIOSIS COPYRIGHT: BIOL ABS. Chromium(VI) anions, along with chromium (III) associated with negatively charged colloids, are sorbed on a macroreticular weak-base anion exchanger DEAE-Sephadex A-25 and then selectively desorbed by reduction with 5% (w/v) hydroxylammonium chloride solution for the determination by graphite-furnace atomic absorption spectrometry. The chromium concentration is increased 100-fold, allowing detection of chromium(VI) down to ca. 0.01 mug/l. Chromium (III) associated with negatively charged colloid is also determined after desorption with 4 mol/l nitric acid.","Separation and determination of chromium(VI) anions and chromium(III) associated with negatively charged colloids in river water by sorption on DEAE-Sephadex A-25 Abs: BIOSIS COPYRIGHT: BIOL ABS. Chromium(VI) anions, along with chromium (III) associated with negatively charged colloids, are sorbed on a macroreticular weak-base anion exchanger DEAE-Sephadex A-25 and then selectively desorbed by reduction with 5% (w/v) hydroxylammonium chloride solution for the determination by graphite-furnace atomic absorption spectrometry. The chromium concentration is increased 100-fold, allowing detection of chromium(VI) down to ca. 0.01 mug/l. Chromium (III) associated with negatively charged colloid is also determined after desorption with 4 mol/l nitric acid."
1515829,Higgins et al. 1997,Traditional and innovative treatment methods for Cr(VI) in soil,"BIOSIS COPYRIGHT: BIOL ABS. There are several treatment technologies available for soils that have elevated levels of chromium. The technologies applicable to a particular chromium site depend on the clean-up goals, the form of the chromium present, and the volume and physical chemical properties of the chromium-containing soils. In many cases the clean-up goals are based on the Cr(VI) concentration in the soils. Therefore, most of the available treatment technologies consist of (1) removing the Cr(VI)-containing soils from the site, (2) immobilizing the chromium so that it will not leach after treatment under field conditions, or (3) reducing the Cr(VI) in the soils to the Cr(III) state. This article discusses the treatment technologies available for each of these remediation strategies, their advantages and disadvantages, and their relative treatment costs. Technologies evaluated include excavation and off-site disposal, soil washing, soil flushing, electrokinetics, solidification/stabilization","Traditional and innovative treatment methods for Cr(VI) in soil Abs: BIOSIS COPYRIGHT: BIOL ABS. There are several treatment technologies available for soils that have elevated levels of chromium. The technologies applicable to a particular chromium site depend on the clean-up goals, the form of the chromium present, and the volume and physical chemical properties of the chromium-containing soils. In many cases the clean-up goals are based on the Cr(VI) concentration in the soils. Therefore, most of the available treatment technologies consist of (1) removing the Cr(VI)-containing soils from the site, (2) immobilizing the chromium so that it will not leach after treatment under field conditions, or (3) reducing the Cr(VI) in the soils to the Cr(III) state. This article discusses the treatment technologies available for each of these remediation strategies, their advantages and disadvantages, and their relative treatment costs. Technologies evaluated include excavation and off-site disposal, soil washing, soil flushing, electrokinetics, solidification/stabilization"
1515827,Higgins et al. 1987,Metal finishing and processing,Biosis copyright: biol abs. rrm review wastewater treatment recycling metal recovery waste disposal land disposal industrial waste metal industry steel industry,Metal finishing and processing Abs: Biosis copyright: biol abs. rrm review wastewater treatment recycling metal recovery waste disposal land disposal industrial waste metal industry steel industry
1515824,Hicks and  Tondorf 1994,Electrorestoration of metal contaminated soils,"BIOSIS COPYRIGHT: BIOL ABS. The removal of metals from contaminated soils using electric fields has been successfully demonstrated in the laboratory, yet field trials have yielded anomalous results. Poor performance may be attributed to interaction of the metals with naturally occurring electrolytes, humic substances, and co-disposed wastes. Immobilization of contaminants in a narrow band in the soil, analogous to isoelectric focusing, was reproduced experimentally and simulated with a mathematical model. It was shown that the focusing effect can be eliminated by controlling the pH at the cathode using a water rinse. Immobilization resulting from precipitation with carbonates and codisposed wastes may additionally require chelating agents and control of the redox potential to effect removal. Pourbaix diagrams provide a means for rapidly identifying pH and redox conditions suitable for mobilizing metal wastes. Optimum operating conditions can then be determined using a mathematical model that incor","Electrorestoration of metal contaminated soils Abs: BIOSIS COPYRIGHT: BIOL ABS. The removal of metals from contaminated soils using electric fields has been successfully demonstrated in the laboratory, yet field trials have yielded anomalous results. Poor performance may be attributed to interaction of the metals with naturally occurring electrolytes, humic substances, and co-disposed wastes. Immobilization of contaminants in a narrow band in the soil, analogous to isoelectric focusing, was reproduced experimentally and simulated with a mathematical model. It was shown that the focusing effect can be eliminated by controlling the pH at the cathode using a water rinse. Immobilization resulting from precipitation with carbonates and codisposed wastes may additionally require chelating agents and control of the redox potential to effect removal. Pourbaix diagrams provide a means for rapidly identifying pH and redox conditions suitable for mobilizing metal wastes. Optimum operating conditions can then be determined using a mathematical model that incor"
1515820,Hickey and  Vickers 1992,Comparison of the sensitivity to heavy metals and pentachlorophenol of the mayflies Deleatidium spp. and the cladoceran Daphnia magna,"BIOSIS COPYRIGHT: BIOL ABS. A laboratory testing protocol has been established for the mayfly Deleatidium spp. This involves incubation of organisms for 96 h at 15êC with continuous aeration. Under these conditions EC50 concentrations for Deleatidium were similar to those for the cladoceran Daphnia magna (48 h test) for four heavy metal toxicants (Cd2+, Cr6+, Cu2+, and Zn2+) and one organic compound (pentachlorophenol). The EC50 concentration for Zn2+ was, however, markedly higher for Deleatidium, indicating lower sensitivity. Deleatidium showed a strong increase in sensitivity with increasing exposure time, suggesting that the organism may be relatively insensitive to short-term ( < 24 h) elevations in heavy-metal concentrations. Comparison with published data for other riverine invertebrates and fish suggests that Deleatidium is among the more sensitive species.","Comparison of the sensitivity to heavy metals and pentachlorophenol of the mayflies Deleatidium spp. and the cladoceran Daphnia magna Abs: BIOSIS COPYRIGHT: BIOL ABS. A laboratory testing protocol has been established for the mayfly Deleatidium spp. This involves incubation of organisms for 96 h at 15êC with continuous aeration. Under these conditions EC50 concentrations for Deleatidium were similar to those for the cladoceran Daphnia magna (48 h test) for four heavy metal toxicants (Cd2+, Cr6+, Cu2+, and Zn2+) and one organic compound (pentachlorophenol). The EC50 concentration for Zn2+ was, however, markedly higher for Deleatidium, indicating lower sensitivity. Deleatidium showed a strong increase in sensitivity with increasing exposure time, suggesting that the organism may be relatively insensitive to short-term ( < 24 h) elevations in heavy-metal concentrations. Comparison with published data for other riverine invertebrates and fish suggests that Deleatidium is among the more sensitive species."
1515818,Hickey et al. 1991,Microtesting appraisal of ATP and cell recovery toxicity end points after acute exposure of Selenastrum capricornutum to selected chemicals,"BIOSIS COPYRIGHT: BIOL ABS. Employing microtesting procedures, intracellular ATP and cell recovery (96-h cell count determinations) were appraised as toxicity end-point responses after acute (4-h) exposure of the green alga Selenastrum capricornutum to metals (Cu2+, Co2+, Cd2+, Cr3+, Cr6+, Ni2+, Hg2+, Zn2+, B3+), sodium azide, and 4 organic compounds (sodium dodecyl sulphate, 2,4-dichlorophenol, phenol, teburthiuron). Except for B3+, both end points were able to measure acute metal, phytotoxicity effects at concentrations of 5 mgovery test showed better metal toxicity discrimination than the ATP test on the basis of dose-response slope steepness and elevation differences. Both tests, however, supplied useful complementary information. While the ATP test reacted rapidly to chemical aggression, the recovery test offered pertinent insight into actual long-term consequences of acute exposure. With the nonmetals, both end-point responses were mitigated (sodium azide, sodium dodecyl sulphate, 2,4-dichlor","Microtesting appraisal of ATP and cell recovery toxicity end points after acute exposure of Selenastrum capricornutum to selected chemicals Abs: BIOSIS COPYRIGHT: BIOL ABS. Employing microtesting procedures, intracellular ATP and cell recovery (96-h cell count determinations) were appraised as toxicity end-point responses after acute (4-h) exposure of the green alga Selenastrum capricornutum to metals (Cu2+, Co2+, Cd2+, Cr3+, Cr6+, Ni2+, Hg2+, Zn2+, B3+), sodium azide, and 4 organic compounds (sodium dodecyl sulphate, 2,4-dichlorophenol, phenol, teburthiuron). Except for B3+, both end points were able to measure acute metal, phytotoxicity effects at concentrations of 5 mgovery test showed better metal toxicity discrimination than the ATP test on the basis of dose-response slope steepness and elevation differences. Both tests, however, supplied useful complementary information. While the ATP test reacted rapidly to chemical aggression, the recovery test offered pertinent insight into actual long-term consequences of acute exposure. With the nonmetals, both end-point responses were mitigated (sodium azide, sodium dodecyl sulphate, 2,4-dichlor"
1515816,Hickey 1989,Sensitivity of four new zealand cladoceran species and daphnia-magna to aquatic toxicants,Biosis copyright: biol abs. rrm daphnia-carinata simocephalus-vetulus ceriodaphnia-dubia ceriodaphnia-pulchella chromium pentachlorophenol boron fluoride biocide,Sensitivity of four new zealand cladoceran species and daphnia-magna to aquatic toxicants Abs: Biosis copyright: biol abs. rrm daphnia-carinata simocephalus-vetulus ceriodaphnia-dubia ceriodaphnia-pulchella chromium pentachlorophenol boron fluoride biocide
1515791,Hewitt and  Madden 1986,Welding Process Parameters and Hexavalent Chromium in MIG Fume,"Tests were carried out to determine the effect of welding parameters on the concentration of hexavalent chromium (7440473) (Cr) dynamic fume age, defined as the time between the formation of the fumes at the arc and their sampling some distance from the arc, during stainless steel metal inert gas welding. The concentration of hexavalent Cr, in terms of percent of the total Cr in the welding fumes, varied according to the parameters of the welding process. The increase of carbon-dioxide content of the shield gas resulted in a decline in the concentration of hexavalent Cr in the fumes; the lack of shielding gas resulted in the generation of a high, but transient concentration of the same product. The addition of ozone (10028156) (O3) increased the concentration of hexavalent Cr with respect to dynamic fume age. The authors conclude that the formation of hexavalent Cr in metal inert welding fumes during the welding of stainless steel is partially due to the occurrence of heterogenous reactions between trivalent Cr oxides and the 03 formed in the arc, and postulate that the creation of a concentric gas shield around the welding arc could increase shielding efficiency by preventing the production of 03 by ultraviolet radiation in the air surrounding the arc.","Welding Process Parameters and Hexavalent Chromium in MIG Fume Abs: Tests were carried out to determine the effect of welding parameters on the concentration of hexavalent chromium (7440473) (Cr) dynamic fume age, defined as the time between the formation of the fumes at the arc and their sampling some distance from the arc, during stainless steel metal inert gas welding. The concentration of hexavalent Cr, in terms of percent of the total Cr in the welding fumes, varied according to the parameters of the welding process. The increase of carbon-dioxide content of the shield gas resulted in a decline in the concentration of hexavalent Cr in the fumes; the lack of shielding gas resulted in the generation of a high, but transient concentration of the same product. The addition of ozone (10028156) (O3) increased the concentration of hexavalent Cr with respect to dynamic fume age. The authors conclude that the formation of hexavalent Cr in metal inert welding fumes during the welding of stainless steel is partially due to the occurrence of heterogenous reactions between trivalent Cr oxides and the 03 formed in the arc, and postulate that the creation of a concentric gas shield around the welding arc could increase shielding efficiency by preventing the production of 03 by ultraviolet radiation in the air surrounding the arc."
1515790,Hewett and  Patil 1982,"Health Hazard Evaluation Determination Report, No. MHETA-80-101-9001, Jones and Laughlin Steel Corporation, Vesta No. 5 General Machine Shop, Mine ID No. 3600960, Fredericksburg, PA","Worker exposure to toxic metal fumes, flux fumes, and gases generated during routine welding and cutting operations at Jones and Laughlin Steel Corporation Vesta No. 5 General Machine Shop (SIC-1211) in Fredericksburg, Pennsylvania, was studied. The investigation was requested by the United Mine Workers of America and was performed on November 14 and 15, 1979. The study was prompted by worker concern over a possible excess of mortality among welders in the shop. A total of 17 welders and 1 blacksmith worked in the welding shop. Some welders were exposed to inorganic nickel (7440020) in concentrations higher than the NIOSH recommended standard of 15 micrograms per cubic meter (mg/m3). Most of the welders were exposed to hexavalent chromium (18540299) in concentrations above the American Conference of Governmental Industrial Hygienists standard of 0.5mg/m3. Three of five 15 minute personal samples exceeded the NIOSH recommended limit of 1.8mg/m3 for nitrogen-dioxide (10102440). It was concluded that there was significant overexposure to nickel, hexavalent chromium, and nitrogen-dioxide. If the shop were to reopen, recommendations involving local exhaust ventilation, other control measures and process design changes should be implemented.","Health Hazard Evaluation Determination Report, No. MHETA-80-101-9001, Jones and Laughlin Steel Corporation, Vesta No. 5 General Machine Shop, Mine ID No. 3600960, Fredericksburg, PA Abs: Worker exposure to toxic metal fumes, flux fumes, and gases generated during routine welding and cutting operations at Jones and Laughlin Steel Corporation Vesta No. 5 General Machine Shop (SIC-1211) in Fredericksburg, Pennsylvania, was studied. The investigation was requested by the United Mine Workers of America and was performed on November 14 and 15, 1979. The study was prompted by worker concern over a possible excess of mortality among welders in the shop. A total of 17 welders and 1 blacksmith worked in the welding shop. Some welders were exposed to inorganic nickel (7440020) in concentrations higher than the NIOSH recommended standard of 15 micrograms per cubic meter (mg/m3). Most of the welders were exposed to hexavalent chromium (18540299) in concentrations above the American Conference of Governmental Industrial Hygienists standard of 0.5mg/m3. Three of five 15 minute personal samples exceeded the NIOSH recommended limit of 1.8mg/m3 for nitrogen-dioxide (10102440). It was concluded that there was significant overexposure to nickel, hexavalent chromium, and nitrogen-dioxide. If the shop were to reopen, recommendations involving local exhaust ventilation, other control measures and process design changes should be implemented."
1515788,Hetmanska et al. 1994,The metal-metal interactions in biological systems: Part II. Saccharomyces cerevisiae,"BIOSIS COPYRIGHT: BIOL ABS. The effect of eleven metal ions: Co(II), Cr(VI), Mg, Mn(II), Mo(VI), Ni(II), Pb(II), Se(IV), Ti(III), V(IV) and Zn and several combinations of them were tested for their effect on the growth of Saccharomyces cerevisiae (Mautner). The effects depended on the metal and its concentration as well as in some cases on the duration of the experiment.","The metal-metal interactions in biological systems: Part II. Saccharomyces cerevisiae Abs: BIOSIS COPYRIGHT: BIOL ABS. The effect of eleven metal ions: Co(II), Cr(VI), Mg, Mn(II), Mo(VI), Ni(II), Pb(II), Se(IV), Ti(III), V(IV) and Zn and several combinations of them were tested for their effect on the growth of Saccharomyces cerevisiae (Mautner). The effects depended on the metal and its concentration as well as in some cases on the duration of the experiment."
1515785,Hess et al. 1998,Assessment management and minimization,Biosis copyright: biol abs. rrm literature review hazardous wastes facility assessment risk assessment soil contamination waste management pollution control assessment management minimization,Assessment management and minimization Abs: Biosis copyright: biol abs. rrm literature review hazardous wastes facility assessment risk assessment soil contamination waste management pollution control assessment management minimization
1515781,Henney et al. 1980,Shock load of chromium(VI),"HEEP COPYRIGHT: BIOL ABS. A 227 kg load of Cr (VI) entered the Mankato, Minnesota (USA) 38,000 m3/day (10 mgd) activated sludge plant over an 18-h period during Oct. 23-24, 1977. The passage of the load through the plant and effects on operations of plant units were followed. About 2/3 of the load appeared in the effluent within 48 h. The remaining 1/3 was reduced to Cr(III) and adsorbed onto sludge particles, ending up in digesters or short-circuited to drying beds. The principal effect was noted in aeration tanks, where a sharp drop in respiration rate of sludge organisms signaled a decrease in assimilation of incoming load.","Shock load of chromium(VI) Abs: HEEP COPYRIGHT: BIOL ABS. A 227 kg load of Cr (VI) entered the Mankato, Minnesota (USA) 38,000 m3/day (10 mgd) activated sludge plant over an 18-h period during Oct. 23-24, 1977. The passage of the load through the plant and effects on operations of plant units were followed. About 2/3 of the load appeared in the effluent within 48 h. The remaining 1/3 was reduced to Cr(III) and adsorbed onto sludge particles, ending up in digesters or short-circuited to drying beds. The principal effect was noted in aeration tanks, where a sharp drop in respiration rate of sludge organisms signaled a decrease in assimilation of incoming load."
1515779,Henderson 1994,Geochemical reduction of hexavalent chromium in the trinity sand aquifer,Biosis copyright: biol abs. rrm research article chromiumiii hydroxide aquifer groundwater contamination plume migration transport model waste site odessa texas usa,Geochemical reduction of hexavalent chromium in the trinity sand aquifer Abs: Biosis copyright: biol abs. rrm research article chromiumiii hydroxide aquifer groundwater contamination plume migration transport model waste site odessa texas usa
1515760,Heikkila et al. 1988,Employees Exposed to Carcinogens in Finland in 1986,"The number of employees in Finland exposed to carcinogens in 1986 was examined. A total of 14,641 workers employed in 1726 work departments were recorded by the Register of Employees Occupationally Exposed to Carcinogens, Helsinki, as being exposed to at least one of 130 carcinogens in 1986. This represented an increase of 2749 over the 1985 total, 11,892. Most of the exposures were to males 25 to 39 years old. The most common carcinogens were hexavalent-chromium (18540299) (Cr+6), nickel (7440020), asbestos (1332214), polycyclic aromatic hydrocarbons, cadmium (7440439), benzene (71432), and arsenic (7440382). By industry, the largest number of carcinogen exposures were to Cr+6 compounds and nickel and its inorganic compounds occurring in manufacturing operations. By occupation, the largest number of carcinogen exposures were to: Cr+6 in welders and flame cutters, metal plate workers and constructional steel erectors; asbestos in machine and engine mechanics; and nickel and its inorganic compounds in welders and flame cutters, metal plate workers and constructional steel erectors, and metal smelting furnace operators. Ninety nine exposures to prohibited substances such as benzidine (92875), 2-naphthylamine (91598), mustard-gas (505602), and 2,3,7,8-tetrachlorodibenzo-p-dioxin (1746016) were reported.","Employees Exposed to Carcinogens in Finland in 1986 Abs: The number of employees in Finland exposed to carcinogens in 1986 was examined. A total of 14,641 workers employed in 1726 work departments were recorded by the Register of Employees Occupationally Exposed to Carcinogens, Helsinki, as being exposed to at least one of 130 carcinogens in 1986. This represented an increase of 2749 over the 1985 total, 11,892. Most of the exposures were to males 25 to 39 years old. The most common carcinogens were hexavalent-chromium (18540299) (Cr+6), nickel (7440020), asbestos (1332214), polycyclic aromatic hydrocarbons, cadmium (7440439), benzene (71432), and arsenic (7440382). By industry, the largest number of carcinogen exposures were to Cr+6 compounds and nickel and its inorganic compounds occurring in manufacturing operations. By occupation, the largest number of carcinogen exposures were to: Cr+6 in welders and flame cutters, metal plate workers and constructional steel erectors; asbestos in machine and engine mechanics; and nickel and its inorganic compounds in welders and flame cutters, metal plate workers and constructional steel erectors, and metal smelting furnace operators. Ninety nine exposures to prohibited substances such as benzidine (92875), 2-naphthylamine (91598), mustard-gas (505602), and 2,3,7,8-tetrachlorodibenzo-p-dioxin (1746016) were reported."
1515757,Hayes and  Theis 1978,The distribution of heavy metals in anaerobic digestion,"HEEP COPYRIGHT: BIOL ABS. Bench scale anaerobic digesters using municipal wastewater sludge were dosed with different levels of heavy metals to determine their distribution and note their effects under operating conditions. Metals investigated were Cr(III), Cr(VI), Cd, Cu(II), Ni, Pb, and Zn. Dosings were made in a stepwise and pulse manner. Characteristic responses were observed during periods of digester distress. These included increased volatile acids and total organic C, decreased gas production and methane composition, and depressed values of pH. The order of toxicity established in this study was Ni > Cu > Pb > Cr(VI)vy metal distribution patterns indicated that metals were rapidly removed from digester supernatant in excess of 95%. The total insoluble portion was divided between inorganic precipitates and the biomass fraction. Between 30-60% of the metals were associated with the bacterial cells. Toxic effects became apparent at or near the maximum metals taken up by this digester component.","The distribution of heavy metals in anaerobic digestion Abs: HEEP COPYRIGHT: BIOL ABS. Bench scale anaerobic digesters using municipal wastewater sludge were dosed with different levels of heavy metals to determine their distribution and note their effects under operating conditions. Metals investigated were Cr(III), Cr(VI), Cd, Cu(II), Ni, Pb, and Zn. Dosings were made in a stepwise and pulse manner. Characteristic responses were observed during periods of digester distress. These included increased volatile acids and total organic C, decreased gas production and methane composition, and depressed values of pH. The order of toxicity established in this study was Ni > Cu > Pb > Cr(VI)vy metal distribution patterns indicated that metals were rapidly removed from digester supernatant in excess of 95%. The total insoluble portion was divided between inorganic precipitates and the biomass fraction. Between 30-60% of the metals were associated with the bacterial cells. Toxic effects became apparent at or near the maximum metals taken up by this digester component."
1515755,Hax and  Buikema 1983,Effects of hexavalent chromium on growth and reproduction of chironomus-riparius diptera,Heep copyright: biol abs. rrm abstract metal toxicity,Effects of hexavalent chromium on growth and reproduction of chironomus-riparius diptera Abs: Heep copyright: biol abs. rrm abstract metal toxicity
1515753,Hawkes 1985,Genotoxicants increase the number of perichromatin granules in pachytene cells of house crickets acheta-domesticus,Biosis copyright: biol abs. rrm abstract dinitroaniline herbicides trifluralin oryzalin mitomycin c zinc beryllium lithium chromium vi cisplatin cadmium boron indium nickel,Genotoxicants increase the number of perichromatin granules in pachytene cells of house crickets acheta-domesticus Abs: Biosis copyright: biol abs. rrm abstract dinitroaniline herbicides trifluralin oryzalin mitomycin c zinc beryllium lithium chromium vi cisplatin cadmium boron indium nickel
1515750,Hatch 2994,Plant Design for Health Protection,"An example is given of the design of a new plant in which potential hazards were determined in advance and steps taken to avoid the hazards. The plant processes chrome ore, converting it to sodium-chromate and bichromate (10588019). The manufacturing process involves four basic steps: handling and processing of solid materials; roasting and delivery to leaching department; leaching; and liquor processing. Exposures of concern in the first and second steps are dusts of different composition. Potential exposures in the third and fourth steps are mists or dried residues from droplets.","Plant Design for Health Protection Abs: An example is given of the design of a new plant in which potential hazards were determined in advance and steps taken to avoid the hazards. The plant processes chrome ore, converting it to sodium-chromate and bichromate (10588019). The manufacturing process involves four basic steps: handling and processing of solid materials; roasting and delivery to leaching department; leaching; and liquor processing. Exposures of concern in the first and second steps are dusts of different composition. Potential exposures in the third and fourth steps are mists or dried residues from droplets."
1515747,Hassan et al. 1996,Hydrogen chromate PVC matrix membrane sensor for potentiometric determination of chromium(III) and chromium(VI) ions,"BIOSIS COPYRIGHT: BIOL ABS. A novel potentiometric Cr6+ PVC matrix membrane sensor incorporating nickel tris(1,10-bathophenanthroline) hydrogen chromate as an electroactive material and 2-nitrophenyl phenyl ether as solvent mediator is described. In a phosphate buffer solution of pH 5, the sensor displays a rapid and linear response for Cr6+ over the concentration range 2 10-2-81 and a detection limit of the order of 0.4 mug ml-1. The sensor is used for sequential determination of Cr6+ and Cr3+ by direct monitoring of Cr6+ followed by oxidation of Cr3+ and measurement of the total chromium. The average recoveries of Cr3+ and Cr6+ at concentration levels of 0.5-50 mug ml-1 are 98.1 | 0.4% and 99.1 | 0.4% respectively. Redox and precipitation titrations involving Cr6+ as a titrant are monitored with the sensor. Cr3+ and/or Cr6+ in wastewaters of some industries (e.g., leather tanning, electroplating, aluminum painting) and the chromium contents of some alloys and refractory bricks are assessed. T","Hydrogen chromate PVC matrix membrane sensor for potentiometric determination of chromium(III) and chromium(VI) ions Abs: BIOSIS COPYRIGHT: BIOL ABS. A novel potentiometric Cr6+ PVC matrix membrane sensor incorporating nickel tris(1,10-bathophenanthroline) hydrogen chromate as an electroactive material and 2-nitrophenyl phenyl ether as solvent mediator is described. In a phosphate buffer solution of pH 5, the sensor displays a rapid and linear response for Cr6+ over the concentration range 2 10-2-81 and a detection limit of the order of 0.4 mug ml-1. The sensor is used for sequential determination of Cr6+ and Cr3+ by direct monitoring of Cr6+ followed by oxidation of Cr3+ and measurement of the total chromium. The average recoveries of Cr3+ and Cr6+ at concentration levels of 0.5-50 mug ml-1 are 98.1 | 0.4% and 99.1 | 0.4% respectively. Redox and precipitation titrations involving Cr6+ as a titrant are monitored with the sensor. Cr3+ and/or Cr6+ in wastewaters of some industries (e.g., leather tanning, electroplating, aluminum painting) and the chromium contents of some alloys and refractory bricks are assessed. T"
1515746,Hassan and  Garrison 1996,Distribution of chromium species between soil and porewater,"BIOSIS COPYRIGHT: BIOL ABS. Batch experiments were carried out using three soils representing different geologic parts of the continental USA to identify processes influencing partitioning and interconversion of chromium species in soil porewaters. The partition coefficient (Kd) of each of the two main species, Cr(III) and Cr(VI), was calculated for each soil using adsorption isotherms measured after an equilibration time of 6 hours for the former species and 48 hours for the latter at the natural conditions of the soils. Cr(VI) in porewater was measured directly by ion chromatography, while total chromium was measured by inductively coupled plasma - atomic emission spectrophotometry (ICP-AES). Total chromium in the soil solids was measured by ICP-AES after microwave assisted digestion. The magnitude of the Kd values are much lower for Cr(VI), ranging from less than 1 to about 50 L kg-1. For Cr(III), the Kd values range from about 850 to 5,600 L kg-1. The effects of the initial porewater concentra","Distribution of chromium species between soil and porewater Abs: BIOSIS COPYRIGHT: BIOL ABS. Batch experiments were carried out using three soils representing different geologic parts of the continental USA to identify processes influencing partitioning and interconversion of chromium species in soil porewaters. The partition coefficient (Kd) of each of the two main species, Cr(III) and Cr(VI), was calculated for each soil using adsorption isotherms measured after an equilibration time of 6 hours for the former species and 48 hours for the latter at the natural conditions of the soils. Cr(VI) in porewater was measured directly by ion chromatography, while total chromium was measured by inductively coupled plasma - atomic emission spectrophotometry (ICP-AES). Total chromium in the soil solids was measured by ICP-AES after microwave assisted digestion. The magnitude of the Kd values are much lower for Cr(VI), ranging from less than 1 to about 50 L kg-1. For Cr(III), the Kd values range from about 850 to 5,600 L kg-1. The effects of the initial porewater concentra"
1515744,Hasnain 1994,Conjugal transfer of chromium resistant plasmids residing in pseudomonads. AU - SULTAN S,"BIOSIS COPYRIGHT: BIOL ABS. Four gram-negative chromium (Cr) resistant strains SPCr-1, SPCr-2, SPCr-3 and SPCr-4, which could tolerate 40 mg ml-1 of potassium chromate in the medium, were isolated from the effluents of ICI Paints, Lahore. On the basis of morphological and biochemical characterization they could be affiliated with family Pseudomonadaceae and especially to genus Pseudomonas (thereafter referred to pseudomonads). They exhibited pleiotropic resistances to various heavy metals and antibiotics. SPCr-1 showed better growth at lower concentrations of chromate (upto 2 mg ml-1) and growth of SPCr-3 was not affected upto 5 mg ml-1 of chromate, while growth of other two pseudomonads decreased in chromate supplemented media. The optimum temperature for the growth of these strains was 37ê C both in the absence and presence (excluding SPCr-3 and SPCr-4, which opted for 28ê C) of chromate. These Cr resistant pseudomonads could grow in wide pH range with pH optima 7 (SPCr-1 and SPCr-2), and 8 (SPC","Conjugal transfer of chromium resistant plasmids residing in pseudomonads. AU - SULTAN S Abs: BIOSIS COPYRIGHT: BIOL ABS. Four gram-negative chromium (Cr) resistant strains SPCr-1, SPCr-2, SPCr-3 and SPCr-4, which could tolerate 40 mg ml-1 of potassium chromate in the medium, were isolated from the effluents of ICI Paints, Lahore. On the basis of morphological and biochemical characterization they could be affiliated with family Pseudomonadaceae and especially to genus Pseudomonas (thereafter referred to pseudomonads). They exhibited pleiotropic resistances to various heavy metals and antibiotics. SPCr-1 showed better growth at lower concentrations of chromate (upto 2 mg ml-1) and growth of SPCr-3 was not affected upto 5 mg ml-1 of chromate, while growth of other two pseudomonads decreased in chromate supplemented media. The optimum temperature for the growth of these strains was 37ê C both in the absence and presence (excluding SPCr-3 and SPCr-4, which opted for 28ê C) of chromate. These Cr resistant pseudomonads could grow in wide pH range with pH optima 7 (SPCr-1 and SPCr-2), and 8 (SPC"
1515684,Hasan 1996,"Destruction of aflatoxin B1 on sorghum grain with acids, salts and ammonia derivatives","BIOSIS COPYRIGHT: BIOL ABS. A study was conducted to determine the effect of eleven different acids, nine derivatives of ammonia and seven salts upon destruction of aflatoxin B1 on sorghum grain. Grain was adjusted to a moisture content of 25% and then treated for 72 h at 25êC. Results suggest that boric, sulphamic and sulphosalicylic acids can be used to effectively destroy aflatoxin B1 in sorghum at 5.0 N concentration. Ammonium nitrate, ammonium chloride and urea were highly effective in aflatoxin degradation at 1.5% on basis of NH4OH nitrogen weight. The use of different types of salts was efficient only in water for aflatoxin B1 destruction.","Destruction of aflatoxin B1 on sorghum grain with acids, salts and ammonia derivatives Abs: BIOSIS COPYRIGHT: BIOL ABS. A study was conducted to determine the effect of eleven different acids, nine derivatives of ammonia and seven salts upon destruction of aflatoxin B1 on sorghum grain. Grain was adjusted to a moisture content of 25% and then treated for 72 h at 25êC. Results suggest that boric, sulphamic and sulphosalicylic acids can be used to effectively destroy aflatoxin B1 in sorghum at 5.0 N concentration. Ammonium nitrate, ammonium chloride and urea were highly effective in aflatoxin degradation at 1.5% on basis of NH4OH nitrogen weight. The use of different types of salts was efficient only in water for aflatoxin B1 destruction."
1515678,Haran et al. 1997,Mathematical modeling of hexavalent chromium decontamination from low surface charged soils,"BIOSIS COPYRIGHT: BIOL ABS. A new electrokinetic technology has been developed for in-situ decontamination of hexavalent chromium in sand. Imposition of a constant potential gradient across the soil matrix through a graphite cathode and iron anode resulted in successful migration of chromate towards the anode. The hexavalent chromium ions are reduced to the harmless trivalent form by chemical reaction with the anodic electrochemical dissolution product, Fe2+. The alkaline front generated at the cathode due to water reduction flushes across the cell and favors faster transport of chromate by enhancing its conductivity. The acidic front generated due to water oxidation at the anode remains adjacent at the electrode-sand interface due to its consumption by the corrosion reaction with iron. The lower production rate of H+ is also due to the competing anodic dissolution reaction. The low pH at the anodic region favors the reduction of hexavalent chromium to its trivalent state. The experimental results","Mathematical modeling of hexavalent chromium decontamination from low surface charged soils Abs: BIOSIS COPYRIGHT: BIOL ABS. A new electrokinetic technology has been developed for in-situ decontamination of hexavalent chromium in sand. Imposition of a constant potential gradient across the soil matrix through a graphite cathode and iron anode resulted in successful migration of chromate towards the anode. The hexavalent chromium ions are reduced to the harmless trivalent form by chemical reaction with the anodic electrochemical dissolution product, Fe2+. The alkaline front generated at the cathode due to water reduction flushes across the cell and favors faster transport of chromate by enhancing its conductivity. The acidic front generated due to water oxidation at the anode remains adjacent at the electrode-sand interface due to its consumption by the corrosion reaction with iron. The lower production rate of H+ is also due to the competing anodic dissolution reaction. The low pH at the anodic region favors the reduction of hexavalent chromium to its trivalent state. The experimental results"
1515677,Hara and  Sonoda 1979,Comparison of the toxicity of heavy metals to cabbage growth,"HEEP COPYRIGHT: BIOL ABS. Cabbage plants (Brassica oleracea L. var. capitata L.) were grown for 55 days with a nutrient solution containing 1 and 10 ppm of V, Cr(III), Cr(VI), Mn, Fe, Co, Ni, Cu, Zn, Cd, Hg(I) or Hg(II). A comparison of the plant growth and chemical analysis revealed that Cr(VI), Cu, Cd, and Hg(II) in the solution are most toxic to the plant growth (hence detrimental to the cabbage-head formation) and Mn, Fe and Zn are less toxic than other heavy metals, and that Mn, Zn, Co, Ni and Cd are translocated into all the plant organs while V, Cr(III), Cr(VI), Fe, Cu, Hg(I) and Hg(II) are accumulated in the roots.","Comparison of the toxicity of heavy metals to cabbage growth Abs: HEEP COPYRIGHT: BIOL ABS. Cabbage plants (Brassica oleracea L. var. capitata L.) were grown for 55 days with a nutrient solution containing 1 and 10 ppm of V, Cr(III), Cr(VI), Mn, Fe, Co, Ni, Cu, Zn, Cd, Hg(I) or Hg(II). A comparison of the plant growth and chemical analysis revealed that Cr(VI), Cu, Cd, and Hg(II) in the solution are most toxic to the plant growth (hence detrimental to the cabbage-head formation) and Mn, Fe and Zn are less toxic than other heavy metals, and that Mn, Zn, Co, Ni and Cd are translocated into all the plant organs while V, Cr(III), Cr(VI), Fe, Cu, Hg(I) and Hg(II) are accumulated in the roots."
1515675,Hara 1981,Determination of chromium compounds in a mixed state of chromium iii and chromium vi,Heep copyright: biol abs. note human chromium vi instrumentation lung cancer occupational health,Determination of chromium compounds in a mixed state of chromium iii and chromium vi Abs: Heep copyright: biol abs. note human chromium vi instrumentation lung cancer occupational health
1515673,Haq et al. 1998,Growth and survival of protozoa isolated from a Tannery effluent,BIOSIS COPYRIGHT: BIOL ABS. Industrial effluent from a tannery was used for the growth of algae in a medium containing various inorganic salts. Growth of algal cells became visible after 7 d. Two species of protozoa were observed to proliferate in the algal culture containing no organic supplement in the medium. The culture was kept bacteria-free by the use of antibiotics and was perpetuated for at least 150 d with no decline in the protozoan population. Efficient growth of protozoa in a culture of algae elucidated new modes of nutrition in protozoa. Cr(VI) was added to the medium to check the resistance of algae and protozoa against this heavy metal. Protozoa showed different degrees of resistance. The results indicate the importance of algae and protozoa in the process of bioremediation.,Growth and survival of protozoa isolated from a Tannery effluent Abs: BIOSIS COPYRIGHT: BIOL ABS. Industrial effluent from a tannery was used for the growth of algae in a medium containing various inorganic salts. Growth of algal cells became visible after 7 d. Two species of protozoa were observed to proliferate in the algal culture containing no organic supplement in the medium. The culture was kept bacteria-free by the use of antibiotics and was perpetuated for at least 150 d with no decline in the protozoan population. Efficient growth of protozoa in a culture of algae elucidated new modes of nutrition in protozoa. Cr(VI) was added to the medium to check the resistance of algae and protozoa against this heavy metal. Protozoa showed different degrees of resistance. The results indicate the importance of algae and protozoa in the process of bioremediation.
1515672,Haq et al. 1999,Cadmium resistant Enterobacter cloacae and Klebsiella sp. isolated from industrial effluents and their possible role in cadmium detoxification,"BIOSIS COPYRIGHT: BIOL ABS. Three bacterial strains, two of Klebsiella sp. and one Enterobacter cloacae were isolated from industrial effluents of chemical and textile industries. They showed high efficiency in removing cadmium (Cd2+) from the medium. When 100 mug/ml of Cd was added to the medium, the three isolates namely CMBL-Cd1, CMBL-Cd2 and CMBL-Cd3 removed or accumulated 86%, 87% and 85% of Cd, respectively, from the medium within 24 h. Plasmids were detected in all the three strains. Plasmids of E. cloacae (pCBL1) a red strains showed lowered resistance against Cr and some antibiotics. This again supported the indication of the presence of Cd, Cr and some antibiotics resistance genes on plasmids.","Cadmium resistant Enterobacter cloacae and Klebsiella sp. isolated from industrial effluents and their possible role in cadmium detoxification Abs: BIOSIS COPYRIGHT: BIOL ABS. Three bacterial strains, two of Klebsiella sp. and one Enterobacter cloacae were isolated from industrial effluents of chemical and textile industries. They showed high efficiency in removing cadmium (Cd2+) from the medium. When 100 mug/ml of Cd was added to the medium, the three isolates namely CMBL-Cd1, CMBL-Cd2 and CMBL-Cd3 removed or accumulated 86%, 87% and 85% of Cd, respectively, from the medium within 24 h. Plasmids were detected in all the three strains. Plasmids of E. cloacae (pCBL1) a red strains showed lowered resistance against Cr and some antibiotics. This again supported the indication of the presence of Cd, Cr and some antibiotics resistance genes on plasmids."
1515615,Hamza et al. 1978,Potential for water resue in an Egyptian poultry processing plant,"HEEP COPYRIGHT: BIOL ABS. The water usage and waste loads were determined for 10 unit operations in a modern poultry processing plant in Alexandria, Egypt. Concentrations of 10 wastewater parameters and 9 heavy metals, identification of 12 bacteria and enumeration of total aerobic and coliform bacteria in the wastewater from these unit operations were determined to evaluate the potential for water reuse. In the scalder, washer and chillers, bacterial counts in the water and on the carcasses were directly related and increased with the length of water usage. Based on the study, countercurrent water use through the chillers and washer was planned after applying renovation measures for grease and bacterial reductions. Compressor cooling water quality was satisfactory for reuse in the scalder.","Potential for water resue in an Egyptian poultry processing plant Abs: HEEP COPYRIGHT: BIOL ABS. The water usage and waste loads were determined for 10 unit operations in a modern poultry processing plant in Alexandria, Egypt. Concentrations of 10 wastewater parameters and 9 heavy metals, identification of 12 bacteria and enumeration of total aerobic and coliform bacteria in the wastewater from these unit operations were determined to evaluate the potential for water reuse. In the scalder, washer and chillers, bacterial counts in the water and on the carcasses were directly related and increased with the length of water usage. Based on the study, countercurrent water use through the chillers and washer was planned after applying renovation measures for grease and bacterial reductions. Compressor cooling water quality was satisfactory for reuse in the scalder."
1515613,Hamilton and  Wetterhahn 1989,Differential effects of chromium(VI) on constitutive and inducible gene expression in chick embryo liver in vivo and correlation with chromium(VI)-induced DNA damage,"The effect of DNA damage induced by the carcinogen chromium(VI) on the function of DNA as a template for transcription of constitutive and inducible genes was examined in chick embryo liver in vivo. Changes in gene expression, determined using solution hybridization and northern blot analyses to measure steady-state mRNA levels and a nuclear run-off assay to measure gene transcription rates, were compared to chromium-DNA binding and to chromium(VI)-induced DNA damage as previously measured by DNA alkaline elution. Chromium(VI) treatment had little or no effect on either the steady-state mRNA levels or the transcription rates of the constitutively expressed genes for albumin, conalbumin (avian transferrin), or B-actin. In contrast, chromium(VI) treatment had significant but opposite effects on the basal and drug-inducible expression of 5-aminolevulinate synthase and cytochrome PB1 P450. The changes in steady-state expression of these two inducible genes were similar to the changes in transcription rate, indicating that the effects of chromium were principally transcriptional. Chromium(VI) treatment increased the basal expression of both inducible genes four- to fivefold at maximum, and the time course of this effect was similar to the time course for chromium(VI)-induced DNA damage and repair. In contrast, chromium(VI) pretreatment suppressed by 60–70% at maximum the subsequent induction of these genes by glutethimide, a phenobarbital analog, and the time course of this effect also corresponded to that of chromium(VI)-induced DNA damage and repair. The time courses of the changes in expression of these genes were bimodal, with the second peak corresponding closely to that of chromium(VI)-induced DNA cross-links. However, the first peak occurred during a period when no DNA cross-links or strand breaks were detectable by alkaline elution, although significant levels of chromium were bound to DNA. This suggests that chromium(VI), like cisplatin, may initially produce a DNA monoadduct that subsequently leads to DNA cross-link formation and that both types of chromium(VI)-induced lesions have a significant effect on the expression of targeted genes.","Differential effects of chromium(VI) on constitutive and inducible gene expression in chick embryo liver in vivo and correlation with chromium(VI)-induced DNA damage Abs: The effect of DNA damage induced by the carcinogen chromium(VI) on the function of DNA as a template for transcription of constitutive and inducible genes was examined in chick embryo liver in vivo. Changes in gene expression, determined using solution hybridization and northern blot analyses to measure steady-state mRNA levels and a nuclear run-off assay to measure gene transcription rates, were compared to chromium-DNA binding and to chromium(VI)-induced DNA damage as previously measured by DNA alkaline elution. Chromium(VI) treatment had little or no effect on either the steady-state mRNA levels or the transcription rates of the constitutively expressed genes for albumin, conalbumin (avian transferrin), or B-actin. In contrast, chromium(VI) treatment had significant but opposite effects on the basal and drug-inducible expression of 5-aminolevulinate synthase and cytochrome PB1 P450. The changes in steady-state expression of these two inducible genes were similar to the changes in transcription rate, indicating that the effects of chromium were principally transcriptional. Chromium(VI) treatment increased the basal expression of both inducible genes four- to fivefold at maximum, and the time course of this effect was similar to the time course for chromium(VI)-induced DNA damage and repair. In contrast, chromium(VI) pretreatment suppressed by 60–70% at maximum the subsequent induction of these genes by glutethimide, a phenobarbital analog, and the time course of this effect also corresponded to that of chromium(VI)-induced DNA damage and repair. The time courses of the changes in expression of these genes were bimodal, with the second peak corresponding closely to that of chromium(VI)-induced DNA cross-links. However, the first peak occurred during a period when no DNA cross-links or strand breaks were detectable by alkaline elution, although significant levels of chromium were bound to DNA. This suggests that chromium(VI), like cisplatin, may initially produce a DNA monoadduct that subsequently leads to DNA cross-link formation and that both types of chromium(VI)-induced lesions have a significant effect on the expression of targeted genes."
1515607,Hall and  Pulliam 1995,An assessment of metals in an estuarine wetlands ecosystem,"BIOSIS COPYRIGHT: BIOL ABS. Biotic and abiotic samples from two physically proximate, temperate, estuarine Hackensack River wetlands (New Jersey) located in highly urbanized areas were analyzed for chromium (total and hexavalent), copper, and lead. The study was performed to determine if chromite ore processing residues (COPR) in fill material surrounding one of the two sites (i.e., the ""Study Site"") were associated with statistically significant higher total chromium concentrations in the biotic media at the Study Site relative to the other site (i.e., the ""Reference Site""). Copper and lead concentrations were evaluated to determine whether other metals may have accumulated at the Study Site due to factors other than COPR. Concentrations of the three metals were evaluated in samples of water, sediment, plant tissue (Phragmites root and shoot tissues), fish tissue (Fundulus sp. whole body tissue), and blue crab tissues (Callinectes sapidus muscle and hepatopancreas tissues). Physical and chemical","An assessment of metals in an estuarine wetlands ecosystem Abs: BIOSIS COPYRIGHT: BIOL ABS. Biotic and abiotic samples from two physically proximate, temperate, estuarine Hackensack River wetlands (New Jersey) located in highly urbanized areas were analyzed for chromium (total and hexavalent), copper, and lead. The study was performed to determine if chromite ore processing residues (COPR) in fill material surrounding one of the two sites (i.e., the ""Study Site"") were associated with statistically significant higher total chromium concentrations in the biotic media at the Study Site relative to the other site (i.e., the ""Reference Site""). Copper and lead concentrations were evaluated to determine whether other metals may have accumulated at the Study Site due to factors other than COPR. Concentrations of the three metals were evaluated in samples of water, sediment, plant tissue (Phragmites root and shoot tissues), fish tissue (Fundulus sp. whole body tissue), and blue crab tissues (Callinectes sapidus muscle and hepatopancreas tissues). Physical and chemical"
1515600,Hadi and  Tarafdar 1986,Adsorption behavior of some metal complexes with ferron on zeo-karb 226 an atomic absorption spectrophotometric study,Biosis copyright: biol abs. rrm iron cadmium lead manganese chromium cobalt nickel copper ph range water pollution,Adsorption behavior of some metal complexes with ferron on zeo-karb 226 an atomic absorption spectrophotometric study Abs: Biosis copyright: biol abs. rrm iron cadmium lead manganese chromium cobalt nickel copper ph range water pollution
1515597,Gupta et al. 1998,Design parameters for fixed bed reactors of activated carbon developed from fertilizer waste for the removal of some heavy metal ions,"BIOSIS COPYRIGHT: BIOL ABS. Activated carbon, developed from fertilizer waste, has been used for the removal of Hg2+, Cr6+, Pb2+, and Cu2+. Mass transfer kinetic approach has been successfully applied for the determination of various parameters necessary for designing a fixed-bed absorber. Parameters selected are the length of the (PAZ) primary adsorption zone (3), total time involved for the establishment of primary adsorption zone (tx), mass rate of flow to the absorber (Fm), time for primary adsorption zone to move down its length (tdelta), amount of adsorbate adsorbed in PAZ from breakpoint to exhaustion (Ms), fractional capacity (f), time of initial formation of PAZ (tf) and per cent saturation of column at break point. Chemical regeneration has been achieved with 1 M HNO3.","Design parameters for fixed bed reactors of activated carbon developed from fertilizer waste for the removal of some heavy metal ions Abs: BIOSIS COPYRIGHT: BIOL ABS. Activated carbon, developed from fertilizer waste, has been used for the removal of Hg2+, Cr6+, Pb2+, and Cu2+. Mass transfer kinetic approach has been successfully applied for the determination of various parameters necessary for designing a fixed-bed absorber. Parameters selected are the length of the (PAZ) primary adsorption zone (3), total time involved for the establishment of primary adsorption zone (tx), mass rate of flow to the absorber (Fm), time for primary adsorption zone to move down its length (tdelta), amount of adsorbate adsorbed in PAZ from breakpoint to exhaustion (Ms), fractional capacity (f), time of initial formation of PAZ (tf) and per cent saturation of column at break point. Chemical regeneration has been achieved with 1 M HNO3."
1515593,Gupta and  Tiwari 1985,Aluminum oxide as adsorbent for removal of hexavalent chromium from aqueous waste,Biosis copyright: biol abs. rrm industrial effluent exothermic ph adsorption capacity electrostatic attraction,Aluminum oxide as adsorbent for removal of hexavalent chromium from aqueous waste Abs: Biosis copyright: biol abs. rrm industrial effluent exothermic ph adsorption capacity electrostatic attraction
1515423,Guerra and  Comodo 1972,Evaluation of tolerance limits of some toxic substances in industrial waste waters by the ichthyo toxicity test,"HEEP COPYRIGHT: BIOL ABS. The ichthyotoxicity test was evaluated for its usefulness in assessing the permissible limit of single toxic substances in liquid industrial waste. Toxic substances frequently present in ground water, i.e. mercury chloride, potassium bichromate, ammonia, phenol, ABS (alkyl benzene sulfonate) and DDT, were tested on 3 species of fish (Carassius auratus, Alburnus albidus and Salmo irideus) of different sensitivity to industrial poisons. S. irideus was the most sensitive. The effect of the poisons on the fish was evaluated by mortality rates after 48 h exposure to the pollutants. This method is not suitable for the evaluation of the presence of quantities of toxic substances in liquid waste larger than the maximal permissible quantities. The method is not sensitive enough in the case of individual toxic substances, but it is of value in the case of mixtures of toxic substances present in industrial effluents.","Evaluation of tolerance limits of some toxic substances in industrial waste waters by the ichthyo toxicity test Abs: HEEP COPYRIGHT: BIOL ABS. The ichthyotoxicity test was evaluated for its usefulness in assessing the permissible limit of single toxic substances in liquid industrial waste. Toxic substances frequently present in ground water, i.e. mercury chloride, potassium bichromate, ammonia, phenol, ABS (alkyl benzene sulfonate) and DDT, were tested on 3 species of fish (Carassius auratus, Alburnus albidus and Salmo irideus) of different sensitivity to industrial poisons. S. irideus was the most sensitive. The effect of the poisons on the fish was evaluated by mortality rates after 48 h exposure to the pollutants. This method is not suitable for the evaluation of the presence of quantities of toxic substances in liquid waste larger than the maximal permissible quantities. The method is not sensitive enough in the case of individual toxic substances, but it is of value in the case of mixtures of toxic substances present in industrial effluents."
1515421,IPCS 1988,Chromium,"Sources of chromium, environmental levels and exposure: Chromium occurs ubiquitously in nature ( < 0.1 ug/m3 in air). Natural levels in uncontaminated waters range from fractions of 1 ug to a few ug/litre. The concentration of chromium in rocks varies from an average of 5 mg/kg (granitic rocks) to 1800 mg/kg (ultramafic/basic and serpentine rocks). The earth's most important deposits are either in the elemental or the trivalent oxidation state. In most soils, chromium occurs in low concentrations (2 60 mg/kg), but values of up to 4 g/kg have been reported in some uncontaminated soils. Only a fraction of this chromium is available to plants. It is not known whether chromium is an essential nutrient for plants, but all plants contain the element (up to 0.19 mg/kg on a wet weight basis). Almost all the hexavalent chromium in the environment arises from human activities. It is derived from the industrial oxidation of mined chromium deposits and possibly from the combustion of fossil fuels, wood, paper, etc. In this oxidation state, chromium is relatively stable in air and pure water, but it is reduced to the trivalent state, when it comes into contact with organic matter in biota, soil, and water. There is an environmental cycle for chromium, from rocks and soils to water, biota, air, and back to the soil. However, a substantial amount (estimated at 6.7 x 106 kg per year) is diverted from this cycle by discharge into streams, and by runoff and dumping into the sea. The ultimate repository is ocean sediment. Chromium compounds are used in ferrochrome production, electroplating, pigment production, and tanning. These industries, the burning of fossil fuels, and waste incineration are sources of chromium in air and water. Most of the liquid effluent from the chromium industries is trapped and disposed of in land fills and sewage sludges, the chromium being in the form of the insoluble trivalent hydroxide. In chromium ore mines, the concentration of chromium in dust ranges from 1.3 to 16.9 mg/m3. During the production of refined ferrochromium, the air in the work-place may contain large amounts of dust (0.03 - 3.2 mg/m3). In chromium plating factories, concentrations of 1 ug/m3 up to 1.4 mg/m3 have been measured. In Portland cement from 9 European countries, the contents of chromium (VI), extractable with sodium sulfate, varied from 1 to 83 g/kg cement. Today, it is generally accepted that only the zero-, di-, tri-, and hexavalent oxidation states have biological importance. The effects of the last 2 oxidation states are so fundamentally different that they must always be considered separately. The trivalent form is an essential nutrient for man, in amounts of 50 - 200 ug/day. Effects on animals: In general, invertebrates are more sensitive to chromium than vertebrates, (acute toxicity for scud < 60 and for fish < 250, hexavalent chromium). Reproduction of Daphnia was affected by exposure to 0.01 mg hexavalent chromium/l. Toxicity for most microorganisms occurs in the range of 0.05-5 mg chromium/kg of medium. Doses of hexavalent chromium greater than 10 mg/kg diet affect mainly the gastrointestinal tract, kidneys, and probably the haematopoetic system. When a similar dose is introduced parenterally, the principal effect is on the kidney, mainly in the proximal convoluted tubules, without evidence of glomerular damage. Toxic effects from trivalent chromium have been reported only following parenteral administration. Dietary toxicity has not been reported, even in studies on cats administered amounts of up to 1 g/day for 1 - 3 months. When intravenously injected in mice, the LD50 of chromium carbonyl was 30 mg/kg body weight; this represents a 10 000-fold excess over the therapeutic dose required to cure signs of chromium deficiency. Many studies on experimental animals have been conducted with chromium compounds in efforts to reproduce cancer similar to that found in man, when exposed to chromium. Most tests have involved subcutaneous, intramuscular, or intrapleural injection. In addition, several hexavalent chromium compou ds have been administered to rats by intrabronchial implantation or intratracheal instillation. Relatively insoluble compounds, calcium chromate, strontium chromate, and certain forms of zinc chromate produced bronchogenic carcinomas; lead chromate, and barium chromate produced weak responses. Intratracheal instillation of soluble sodium dichromate and dissolved calcium chromate produced bronchogenic tumours. Injection of lead chromate, lead chromate oxide, and cobalt-chromium alloy resulted in the production of local sarcomas. Thus, there is sufficient evidence that certain hexavalent chromium compounds are carcinogenic for experimental animals. No increased tumour incidence was observed when trivalent compounds were given orally; however, the doses administered were low. Hexavalent chromium has been reported to cause various forms of genetic damage in short-term mutagenicity tests, including damage to DNA, and misincoporation of nucleotides in DNA transcription. It was mutagenic in bacteria in the absence of an exogenous metabolic activation system, and in fungi. Hexavalent chromium was also mutagenic in mammalian cells in vitro and in vivo. Hexavalent chromium caused chromosomal aberrations and sister chromatid exchanges in mammalian cells in vitro. A few positive results in in vitro assays for mammalian cell chromosomal aberrations and sister chromatid exchanges were obtained only with very high doses and could be explained by nonspecific toxic effects. It induced formation of micronuclei in mice in vivo. Potassium dichromate induced dominant lethal mutations in mice treated in vivo. Trivalent chromium is genetically active only in in vitro tests, where it can have a direct interaction with DNA, e.g. in experiments using purified DNA or tests to measure decreased fidelity of DNA synthesis in vitro. Reduction of chromium (VI) within the cell nucleus and the formation of chromium (III) complexes suggests that chromium (III) would be the ultimate mutagenic form of chromium. Trivalent chromium was present in RNAs from all sources examined and probably contributes to the stability of the structure. Injected chromium trichloride (CrCl3) accumulated in the cell nucleus (up to 20% of cellular chromium content). It enhanced RNA synthesis in mice and in regenerating rat liver, suggesting that chromium (III) is involved directly in RNA synthesis. On the other hand, chromium (VI) inhibited RNA synthesis and DNA replication in several systems. Evaluation of risks for human health: Chromium in the form of trivalent compounds is an essential nutrient. The daily human intake of chromium varies considerably between regions. Typical values range from 50 to ug/day. Such intakes do not represent a toxicity problem, and they coincide with the calculated human requirements. Not enough data are available for a quantitative assessment of the risk of chromium deficiency in different populations. Evidence from studies on experimental animals shows that hexavalent chromium compounds, especially those of low solubility can induce lung cancer. Mutagenicity and related studies have shown convincingly that hexavalent chromium is genetically active. On the other hand, trivalent chromium compounds are inactive in most test systems, except in systems where they can directly interact with DNA. Both oxidation states, when injected at high levels parenterally in animals, are teratogenic, with the hexavalent form accumulating in the embryos to a much greater extent than the trivalent. A number of effects can result from occupational exposure to airborne chromium, including irritative lesions of the skin and upper respiratory tract, allergic reactions, and cancers of the respiratory tract. The data on other effects in, e.g., the gastrointestinal, cardiovascular, and urogenital systems are insufficient for evaluation. Epidemiological studies have shown that workers engaged in the production of chromate salts and chromate pigments are at increased risk of developing bronchial carcinoma. No detailed data on dose-response relationships are available. Although a suspicion of increased lung cancer risks in chromium-plating workers has been raised, the available data are inconclusive and so are data for other industrial processes where chromium Compounds are used rather than produced. There is insufficient evidence to implicate chromium as a causative agent of cancer in any organ other than the lung. The frequency of sister chromatid exchanges in the lymphocytes of workers in chromium-plating factories was higher than in control groups. The general population living in the vicinity of ferro-alloy plants and exposed to ambient air concentrations of up to 1 ug/m3 did not show increased lung cancer mortality. The results of many studies suggest that exposure to chromium through inhalation and skin contact can pose health problems for the general population, but no data on dose-response relationships are available. Thus, there is no reason, at present, to be concerned that chromium in the air presents a health problem, except under conditions of industrial exposure.","Chromium Abs: Sources of chromium, environmental levels and exposure: Chromium occurs ubiquitously in nature ( < 0.1 ug/m3 in air). Natural levels in uncontaminated waters range from fractions of 1 ug to a few ug/litre. The concentration of chromium in rocks varies from an average of 5 mg/kg (granitic rocks) to 1800 mg/kg (ultramafic/basic and serpentine rocks). The earth's most important deposits are either in the elemental or the trivalent oxidation state. In most soils, chromium occurs in low concentrations (2 60 mg/kg), but values of up to 4 g/kg have been reported in some uncontaminated soils. Only a fraction of this chromium is available to plants. It is not known whether chromium is an essential nutrient for plants, but all plants contain the element (up to 0.19 mg/kg on a wet weight basis). Almost all the hexavalent chromium in the environment arises from human activities. It is derived from the industrial oxidation of mined chromium deposits and possibly from the combustion of fossil fuels, wood, paper, etc. In this oxidation state, chromium is relatively stable in air and pure water, but it is reduced to the trivalent state, when it comes into contact with organic matter in biota, soil, and water. There is an environmental cycle for chromium, from rocks and soils to water, biota, air, and back to the soil. However, a substantial amount (estimated at 6.7 x 106 kg per year) is diverted from this cycle by discharge into streams, and by runoff and dumping into the sea. The ultimate repository is ocean sediment. Chromium compounds are used in ferrochrome production, electroplating, pigment production, and tanning. These industries, the burning of fossil fuels, and waste incineration are sources of chromium in air and water. Most of the liquid effluent from the chromium industries is trapped and disposed of in land fills and sewage sludges, the chromium being in the form of the insoluble trivalent hydroxide. In chromium ore mines, the concentration of chromium in dust ranges from 1.3 to 16.9 mg/m3. During the production of refined ferrochromium, the air in the work-place may contain large amounts of dust (0.03 - 3.2 mg/m3). In chromium plating factories, concentrations of 1 ug/m3 up to 1.4 mg/m3 have been measured. In Portland cement from 9 European countries, the contents of chromium (VI), extractable with sodium sulfate, varied from 1 to 83 g/kg cement. Today, it is generally accepted that only the zero-, di-, tri-, and hexavalent oxidation states have biological importance. The effects of the last 2 oxidation states are so fundamentally different that they must always be considered separately. The trivalent form is an essential nutrient for man, in amounts of 50 - 200 ug/day. Effects on animals: In general, invertebrates are more sensitive to chromium than vertebrates, (acute toxicity for scud < 60 and for fish < 250, hexavalent chromium). Reproduction of Daphnia was affected by exposure to 0.01 mg hexavalent chromium/l. Toxicity for most microorganisms occurs in the range of 0.05-5 mg chromium/kg of medium. Doses of hexavalent chromium greater than 10 mg/kg diet affect mainly the gastrointestinal tract, kidneys, and probably the haematopoetic system. When a similar dose is introduced parenterally, the principal effect is on the kidney, mainly in the proximal convoluted tubules, without evidence of glomerular damage. Toxic effects from trivalent chromium have been reported only following parenteral administration. Dietary toxicity has not been reported, even in studies on cats administered amounts of up to 1 g/day for 1 - 3 months. When intravenously injected in mice, the LD50 of chromium carbonyl was 30 mg/kg body weight; this represents a 10 000-fold excess over the therapeutic dose required to cure signs of chromium deficiency. Many studies on experimental animals have been conducted with chromium compounds in efforts to reproduce cancer similar to that found in man, when exposed to chromium. Most tests have involved subcutaneous, intramuscular, or intrapleural injection. In addition, several hexavalent chromium compou ds have been administered to rats by intrabronchial implantation or intratracheal instillation. Relatively insoluble compounds, calcium chromate, strontium chromate, and certain forms of zinc chromate produced bronchogenic carcinomas; lead chromate, and barium chromate produced weak responses. Intratracheal instillation of soluble sodium dichromate and dissolved calcium chromate produced bronchogenic tumours. Injection of lead chromate, lead chromate oxide, and cobalt-chromium alloy resulted in the production of local sarcomas. Thus, there is sufficient evidence that certain hexavalent chromium compounds are carcinogenic for experimental animals. No increased tumour incidence was observed when trivalent compounds were given orally; however, the doses administered were low. Hexavalent chromium has been reported to cause various forms of genetic damage in short-term mutagenicity tests, including damage to DNA, and misincoporation of nucleotides in DNA transcription. It was mutagenic in bacteria in the absence of an exogenous metabolic activation system, and in fungi. Hexavalent chromium was also mutagenic in mammalian cells in vitro and in vivo. Hexavalent chromium caused chromosomal aberrations and sister chromatid exchanges in mammalian cells in vitro. A few positive results in in vitro assays for mammalian cell chromosomal aberrations and sister chromatid exchanges were obtained only with very high doses and could be explained by nonspecific toxic effects. It induced formation of micronuclei in mice in vivo. Potassium dichromate induced dominant lethal mutations in mice treated in vivo. Trivalent chromium is genetically active only in in vitro tests, where it can have a direct interaction with DNA, e.g. in experiments using purified DNA or tests to measure decreased fidelity of DNA synthesis in vitro. Reduction of chromium (VI) within the cell nucleus and the formation of chromium (III) complexes suggests that chromium (III) would be the ultimate mutagenic form of chromium. Trivalent chromium was present in RNAs from all sources examined and probably contributes to the stability of the structure. Injected chromium trichloride (CrCl3) accumulated in the cell nucleus (up to 20% of cellular chromium content). It enhanced RNA synthesis in mice and in regenerating rat liver, suggesting that chromium (III) is involved directly in RNA synthesis. On the other hand, chromium (VI) inhibited RNA synthesis and DNA replication in several systems. Evaluation of risks for human health: Chromium in the form of trivalent compounds is an essential nutrient. The daily human intake of chromium varies considerably between regions. Typical values range from 50 to ug/day. Such intakes do not represent a toxicity problem, and they coincide with the calculated human requirements. Not enough data are available for a quantitative assessment of the risk of chromium deficiency in different populations. Evidence from studies on experimental animals shows that hexavalent chromium compounds, especially those of low solubility can induce lung cancer. Mutagenicity and related studies have shown convincingly that hexavalent chromium is genetically active. On the other hand, trivalent chromium compounds are inactive in most test systems, except in systems where they can directly interact with DNA. Both oxidation states, when injected at high levels parenterally in animals, are teratogenic, with the hexavalent form accumulating in the embryos to a much greater extent than the trivalent. A number of effects can result from occupational exposure to airborne chromium, including irritative lesions of the skin and upper respiratory tract, allergic reactions, and cancers of the respiratory tract. The data on other effects in, e.g., the gastrointestinal, cardiovascular, and urogenital systems are insufficient for evaluation. Epidemiological studies have shown that workers engaged in the production of chromate salts and chromate pigments are at increased risk of developing bronchial carcinoma. No detailed data on dose-response relationships are available. Although a suspicion of increased lung cancer risks in chromium-plating workers has been raised, the available data are inconclusive and so are data for other industrial processes where chromium Compounds are used rather than produced. There is insufficient evidence to implicate chromium as a causative agent of cancer in any organ other than the lung. The frequency of sister chromatid exchanges in the lymphocytes of workers in chromium-plating factories was higher than in control groups. The general population living in the vicinity of ferro-alloy plants and exposed to ambient air concentrations of up to 1 ug/m3 did not show increased lung cancer mortality. The results of many studies suggest that exposure to chromium through inhalation and skin contact can pose health problems for the general population, but no data on dose-response relationships are available. Thus, there is no reason, at present, to be concerned that chromium in the air presents a health problem, except under conditions of industrial exposure."
1515419,Grosse 1986,Review of alternative treatment processes for metal-bearing hazardous waste streams,"HMTC Alternative treatment processes for metal-bearing hazardous waste streams are reviewed. Precipitation is the preferred treatment process for removing toxic heavy metals from electroplating waters. Precipitation processes include hydroxide, lime and/or sulfide treatment. Chemical reduction is used to treat complex metals such as nickle, copper, hexavalent chromium waste, soluble lead, silver, metal containing cyanide, and mercury. Adsorption has shown potential for treating and polishing aqueous metal bearing wastes. Activated carbon, activated alumina, and iron filings are all applicable adsorbents. Alkaline chlorination and incineration are effective cyanide destruction treatments. Evaporation, ion-exchange, reverse osmosis, electrodialysis, and electrolytic recovery are waste reduction and recovery techniques applicable to metal-bearing hazardous streams. (18 ref.)","Review of alternative treatment processes for metal-bearing hazardous waste streams Abs: HMTC Alternative treatment processes for metal-bearing hazardous waste streams are reviewed. Precipitation is the preferred treatment process for removing toxic heavy metals from electroplating waters. Precipitation processes include hydroxide, lime and/or sulfide treatment. Chemical reduction is used to treat complex metals such as nickle, copper, hexavalent chromium waste, soluble lead, silver, metal containing cyanide, and mercury. Adsorption has shown potential for treating and polishing aqueous metal bearing wastes. Activated carbon, activated alumina, and iron filings are all applicable adsorbents. Alkaline chlorination and incineration are effective cyanide destruction treatments. Evaporation, ion-exchange, reverse osmosis, electrodialysis, and electrolytic recovery are waste reduction and recovery techniques applicable to metal-bearing hazardous streams. (18 ref.)"
1515417,Gromadzi?ska et al. 1996,The influence of atmospheric chromium on selenium content and glutathione peroxidase activity in blood of tannery workers,"The concentration of selenium and thiobarbituric acid reactive substances (TBARS) and activity of glutathione peroxidase (GSH-Px) were determined in blood of 34 workers of a tannery in Gniezno, Poland, who worked in an area containing chromium compounds. Fourteen workers were exposed to chromium compounds at concentrations of 0.11 +/- 0.07 mg Cr/m3 (mean +/- SD) and 20 at concentrations 5-10 times lower i.e., 0.022 +/- 0.009 mg Cr/m3. Excretion of Se in urine was measured in all of the investigated workers. Decreased Se concentration in whole blood and blood plasma and elevated TBARS concentration in blood plasma were found in the whole group of investigated tanners as compared to controls. Tanners working in areas with high chromium concentrations had a statistically significant decrease in Se concentration in blood and plasma and decreased urinary excretion of the microelement as compared with other tanners. TBARS concentration was 2.5 times lower in workers exposed to higher chromium concentrations (p < 0.005) than in other workers. Positive linear correlations were found between the concentration of Se in blood and the amount of the element excreted in urine (r = 0.48; p < 0.005), the concentration of Se in blood plasma and in urine (r = 0.46; p < 0.01), and the concentration of Se in blood and erythrocyte GSH-Px activity (r = 0.42; p < 0.02). The observed differences between Se concentration in blood and urine of tannery workers and people who are not employed in the industry may indicate a kind of specific adaptation of the body to the working environment containing chromium compounds.","The influence of atmospheric chromium on selenium content and glutathione peroxidase activity in blood of tannery workers Abs: The concentration of selenium and thiobarbituric acid reactive substances (TBARS) and activity of glutathione peroxidase (GSH-Px) were determined in blood of 34 workers of a tannery in Gniezno, Poland, who worked in an area containing chromium compounds. Fourteen workers were exposed to chromium compounds at concentrations of 0.11 +/- 0.07 mg Cr/m3 (mean +/- SD) and 20 at concentrations 5-10 times lower i.e., 0.022 +/- 0.009 mg Cr/m3. Excretion of Se in urine was measured in all of the investigated workers. Decreased Se concentration in whole blood and blood plasma and elevated TBARS concentration in blood plasma were found in the whole group of investigated tanners as compared to controls. Tanners working in areas with high chromium concentrations had a statistically significant decrease in Se concentration in blood and plasma and decreased urinary excretion of the microelement as compared with other tanners. TBARS concentration was 2.5 times lower in workers exposed to higher chromium concentrations (p < 0.005) than in other workers. Positive linear correlations were found between the concentration of Se in blood and the amount of the element excreted in urine (r = 0.48; p < 0.005), the concentration of Se in blood plasma and in urine (r = 0.46; p < 0.01), and the concentration of Se in blood and erythrocyte GSH-Px activity (r = 0.42; p < 0.02). The observed differences between Se concentration in blood and urine of tannery workers and people who are not employed in the industry may indicate a kind of specific adaptation of the body to the working environment containing chromium compounds."
1515413,Greene and  Darnall 1988,Temperature dependence of metal ion sorption by spirulina,Biosis copyright: biol abs. rrm copper cadmium lead zinc chromium gold heavy metal toxicity,Temperature dependence of metal ion sorption by spirulina Abs: Biosis copyright: biol abs. rrm copper cadmium lead zinc chromium gold heavy metal toxicity
1515411,Grazia Corradi and  Gorbi 1993,Chromium toxicity on two linked trophic levels: II. Morphophysiological effects on Scenedesmus acutus,"BIOSIS COPYRIGHT: BIOL ABS. The morphophysiological effects of Cr(VI) on Scenedesmus acutus were studied by light and fluorescence microscopy. Axenic cultures of S. acutus were grown in the presence of 1, 5, and 10 mg/liter of Cr(VI) supplied as K2Cr2O7. It was found that Cr(VI) inhibits cell proliferation and the formation of coenobia. It also induces alterations in cell morphology; depending on the dose, it induces the formation of multicellular plurinucleated aggregates or the appearance of large uninucleated cells. By using methylene blue staining, it was possible to identify the algal cells that had undergone irreversible damage.","Chromium toxicity on two linked trophic levels: II. Morphophysiological effects on Scenedesmus acutus Abs: BIOSIS COPYRIGHT: BIOL ABS. The morphophysiological effects of Cr(VI) on Scenedesmus acutus were studied by light and fluorescence microscopy. Axenic cultures of S. acutus were grown in the presence of 1, 5, and 10 mg/liter of Cr(VI) supplied as K2Cr2O7. It was found that Cr(VI) inhibits cell proliferation and the formation of coenobia. It also induces alterations in cell morphology; depending on the dose, it induces the formation of multicellular plurinucleated aggregates or the appearance of large uninucleated cells. By using methylene blue staining, it was possible to identify the algal cells that had undergone irreversible damage."
1515409,Gray and  Hewitt 1982,Control Of Particulate Emissions From Electric Arc Welding By Process Modification,"Welding modifications to control particulate emission from electric arcs are reviewed. The hazards of complex air contaminants such as welding fumes can be reduced at the source by reducing the rate of formation or changing its composition to reduce its toxicity. Metal fume formation which involves oxidation processes are suppressed by preventing contact of the hot metal with oxidizing gases. In inert shielding processes, the inert shielding gas reduces the potential for oxidation enhanced fume formation. Addition of oxygen or carbon-dioxide to this system stabilizes the arc but increases fume formation rates. In inert gas welding it is possible to suppress fumes by extending the gas shielding area. The rate of spread may be reduced by applying voltage, inert shield gases, selected shield gas mixtures which produce low current spray transfer, high surface purity welding wires, and transistorized power source. In manual metal arc welding, fume formation rates are reduced by selecting an appropriate formulation. Fume composition may be altered by changing welding parameters or filler composition and undesirable elements from filler wire can thus be eliminated. Flux formulation in manual metal arc welding may be modified by removing the binding agents such as sodium (7440235), potassium (7440097), and silicates and using appropriate substitutes. The composition of welding fumes is influenced by the various parameters of the process; during metal inert gas welding of steel, hexavalent chromium (18540299) is produced due to transfer and high spread rates. The latter may be eliminated by welding under conditions of spray transfer. Specific changes to welding equipment such as modification of torch design or using special welding wires can also produce improvements. The authors conclude that for each welding process, the selection of a combination of equipment, materials, and operating conditions which minimize the hazards of the particulate fumes should be considered.","Control Of Particulate Emissions From Electric Arc Welding By Process Modification Abs: Welding modifications to control particulate emission from electric arcs are reviewed. The hazards of complex air contaminants such as welding fumes can be reduced at the source by reducing the rate of formation or changing its composition to reduce its toxicity. Metal fume formation which involves oxidation processes are suppressed by preventing contact of the hot metal with oxidizing gases. In inert shielding processes, the inert shielding gas reduces the potential for oxidation enhanced fume formation. Addition of oxygen or carbon-dioxide to this system stabilizes the arc but increases fume formation rates. In inert gas welding it is possible to suppress fumes by extending the gas shielding area. The rate of spread may be reduced by applying voltage, inert shield gases, selected shield gas mixtures which produce low current spray transfer, high surface purity welding wires, and transistorized power source. In manual metal arc welding, fume formation rates are reduced by selecting an appropriate formulation. Fume composition may be altered by changing welding parameters or filler composition and undesirable elements from filler wire can thus be eliminated. Flux formulation in manual metal arc welding may be modified by removing the binding agents such as sodium (7440235), potassium (7440097), and silicates and using appropriate substitutes. The composition of welding fumes is influenced by the various parameters of the process; during metal inert gas welding of steel, hexavalent chromium (18540299) is produced due to transfer and high spread rates. The latter may be eliminated by welding under conditions of spray transfer. Specific changes to welding equipment such as modification of torch design or using special welding wires can also produce improvements. The authors conclude that for each welding process, the selection of a combination of equipment, materials, and operating conditions which minimize the hazards of the particulate fumes should be considered."
1515407,Gray et al. 1983,The Evolution of Hexavalent Chromium in Metallic Aerosols,"Experiments were described which investigated the kinetics of hexavalent chromium (7440473) (Cr) formation and decay in welding fumes, both airborne and collected on filters. Metal inert gas (MIG) and manual metal arc (MMA) welding operations, using stainless steel, were performed automatically to eliminate variabilities in fume formation rate and composition. Fume samples were collected on glass fiber filters or in an impinger train. In each case ten samples were collected simultaneously for analysis at various times after collection, in order to investigate the effects of aging. Atomic absorption spectrometry was used to examine the samples for iron, total Cr and chromium(VI) (Cr(VI)). No significant differences were detected in the ratios of Cr(VI) to total Cr in the glass fiber filter samples of either MIG or MMA fumes following the first 90 seconds after collection. This ratio also did not vary with age for MMA fumes collected in the impinger. However, MIG fumes collected by impinger showed significant variations in the ratio of Cr(VI) to total Cr with age. The ratio rose sharply to a maximum at 20 seconds, then fell and reached a steady value within a few minutes. Preliminary field trials were conducted using both collection methods during MIG welding of stainless steel. The amount of total Cr collected by the two methods was very similar, although the impinger method gave concentrations of airborne Cr(VI) of 2 to 5 times larger than that measured simultaneously by filter sampling. The authors conclude that serious underestimates of exposure of workers close to fume sources could result from use of the filter collection technique.","The Evolution of Hexavalent Chromium in Metallic Aerosols Abs: Experiments were described which investigated the kinetics of hexavalent chromium (7440473) (Cr) formation and decay in welding fumes, both airborne and collected on filters. Metal inert gas (MIG) and manual metal arc (MMA) welding operations, using stainless steel, were performed automatically to eliminate variabilities in fume formation rate and composition. Fume samples were collected on glass fiber filters or in an impinger train. In each case ten samples were collected simultaneously for analysis at various times after collection, in order to investigate the effects of aging. Atomic absorption spectrometry was used to examine the samples for iron, total Cr and chromium(VI) (Cr(VI)). No significant differences were detected in the ratios of Cr(VI) to total Cr in the glass fiber filter samples of either MIG or MMA fumes following the first 90 seconds after collection. This ratio also did not vary with age for MMA fumes collected in the impinger. However, MIG fumes collected by impinger showed significant variations in the ratio of Cr(VI) to total Cr with age. The ratio rose sharply to a maximum at 20 seconds, then fell and reached a steady value within a few minutes. Preliminary field trials were conducted using both collection methods during MIG welding of stainless steel. The amount of total Cr collected by the two methods was very similar, although the impinger method gave concentrations of airborne Cr(VI) of 2 to 5 times larger than that measured simultaneously by filter sampling. The authors conclude that serious underestimates of exposure of workers close to fume sources could result from use of the filter collection technique."
1515379,Grattan et al. 1989,Cutting fluid dermatitis,Biosis copyright: biol abs. rrm workers allergy irritant contact dermatitis biocides formaldehyde releasers occupational health and safety,Cutting fluid dermatitis Abs: Biosis copyright: biol abs. rrm workers allergy irritant contact dermatitis biocides formaldehyde releasers occupational health and safety
1515366,Gould 1982,The kinetics of hexavalent chromium reduction by metallic iron,"HEEP COPYRIGHT: BIOL ABS. The rate reduction of Cr(VI) by metallic Fe under a range of conditions was studied in batch systems. The chemical variables studied were the Cr(VI) concentration, H ion concentration and surface area of Fe. The influence of ionic strength and mixing rate was also examined. The reaction kinetics were dependent on H ion concentration, Cr(VI) concentration and Fe surface area and adhered to the following kinetic expression: %W%000440%% The rate constant was evaluated and had a value of 5.45itions. The rate constant increased as mixing rate increased up to a maximum value beyond which the rate was essentially independent of mixing. Increases in ionic strength resulted in a rapid decrease in the rate constant at ionic strengths < 0.1 M. Further increases in ionic strength had no detectable impact on the rate constant. All rate determination studies were run in the mixing and ionic strength independent regions of these systems. Reaction stoichiometry was, with 1 exception, independent of environmental conditions. In general, 1.33 mol Fe dissolved for each mol Cr(VI) reduced. This highly efficient utilization of Fe in the reduction suggested that H generated during Fe dissolution may have acted as a reductant for the Cr(VI). The single parameter which influenced the reaction stoichiometry was the initial Cr(VI) concentration. The ratio of Cr(VI) reduced to Fe dissolved increased rapidly as the Cr(VI) concentration increased. This observation was consistent with a surface interaction between Cr(VI) and some metastable H species at the Fe surface.","The kinetics of hexavalent chromium reduction by metallic iron Abs: HEEP COPYRIGHT: BIOL ABS. The rate reduction of Cr(VI) by metallic Fe under a range of conditions was studied in batch systems. The chemical variables studied were the Cr(VI) concentration, H ion concentration and surface area of Fe. The influence of ionic strength and mixing rate was also examined. The reaction kinetics were dependent on H ion concentration, Cr(VI) concentration and Fe surface area and adhered to the following kinetic expression: %W%000440%% The rate constant was evaluated and had a value of 5.45itions. The rate constant increased as mixing rate increased up to a maximum value beyond which the rate was essentially independent of mixing. Increases in ionic strength resulted in a rapid decrease in the rate constant at ionic strengths < 0.1 M. Further increases in ionic strength had no detectable impact on the rate constant. All rate determination studies were run in the mixing and ionic strength independent regions of these systems. Reaction stoichiometry was, with 1 exception, independent of environmental conditions. In general, 1.33 mol Fe dissolved for each mol Cr(VI) reduced. This highly efficient utilization of Fe in the reduction suggested that H generated during Fe dissolution may have acted as a reductant for the Cr(VI). The single parameter which influenced the reaction stoichiometry was the initial Cr(VI) concentration. The ratio of Cr(VI) reduced to Fe dissolved increased rapidly as the Cr(VI) concentration increased. This observation was consistent with a surface interaction between Cr(VI) and some metastable H species at the Fe surface."
1515364,Gorman 1979,"Hazard Evaluation and Technical Assistance Report No. TA-78-63 USDAorest Service, Washington, D.C","An industrial hygiene survey was conducted in three Forest Ranger Districts of the Mark Twain National Forest (SIC-0851) in Missouri from April 23 to 27, 1979. The survey was requested by the Forest Service to determine worker exposure to elements of tree marking paint. Personal air samples were analyzed for inorganic lead (7439921) and hexavalent chromium (18540299) content. Concentrations of both substances were undetectable and consequently, below the OSHA standards of 50 micrograms per cubic meter of air for lead, and 200 micrograms per cubic meter of air for hexavalent chromium. The results indicate that no exposure hazard existed, probably because these chemicals are applied in outdoor, well ventilated settings. Recommendations resulting from the survey advise the prudent use of cleaning solvents, adherence to good personal hygiene habits, and wearing of protective clothing.","Hazard Evaluation and Technical Assistance Report No. TA-78-63 USDAorest Service, Washington, D.C Abs: An industrial hygiene survey was conducted in three Forest Ranger Districts of the Mark Twain National Forest (SIC-0851) in Missouri from April 23 to 27, 1979. The survey was requested by the Forest Service to determine worker exposure to elements of tree marking paint. Personal air samples were analyzed for inorganic lead (7439921) and hexavalent chromium (18540299) content. Concentrations of both substances were undetectable and consequently, below the OSHA standards of 50 micrograms per cubic meter of air for lead, and 200 micrograms per cubic meter of air for hexavalent chromium. The results indicate that no exposure hazard existed, probably because these chemicals are applied in outdoor, well ventilated settings. Recommendations resulting from the survey advise the prudent use of cleaning solvents, adherence to good personal hygiene habits, and wearing of protective clothing."
1515340,Gorbi and  Grazia Corradi 1993,Chromium toxicity on two linked trophic levels: I. Effects of contaminated algae on Daphnia magna,"BIOSIS COPYRIGHT: BIOL ABS. The effects of feeding Daphnia magna on algae (Scenedesmus acutus) pretreated with different concentrations of Cr(VI) were studied. A positive effect on growth and newborn production rate was observed in the daphnids fed on algae exposed to 1 mg/liter Cr(VI). Fecundity and growth were drastically reduced in daphnids fed on algae exposed to 10 mg/liter Cr(VI). Since the algae, cultured in the presence of these two Cr(VI) concentrations, supplied daphnids with similar amounts of chromium, the observed effects on the population dynamics of D. magna were attributed more to alterations of the nutritional value of the algal food, due to the Cr treatment, than to a toxic effect of the metal.","Chromium toxicity on two linked trophic levels: I. Effects of contaminated algae on Daphnia magna Abs: BIOSIS COPYRIGHT: BIOL ABS. The effects of feeding Daphnia magna on algae (Scenedesmus acutus) pretreated with different concentrations of Cr(VI) were studied. A positive effect on growth and newborn production rate was observed in the daphnids fed on algae exposed to 1 mg/liter Cr(VI). Fecundity and growth were drastically reduced in daphnids fed on algae exposed to 10 mg/liter Cr(VI). Since the algae, cultured in the presence of these two Cr(VI) concentrations, supplied daphnids with similar amounts of chromium, the observed effects on the population dynamics of D. magna were attributed more to alterations of the nutritional value of the algal food, due to the Cr treatment, than to a toxic effect of the metal."
1515338,Gorbi et al. 1996,Comparison between a normal and a Cr-tolerant strain of Scenedesmus acutus as a food source to Daphnia magna,"BIOSIS COPYRIGHT: BIOL ABS. A normal (S2-N) and a Cr-tolerant (S2-T) strain of Scenedesmus acutus, grown in Cr-free medium or in the presence of 1, 5, or 10 mg/liter Cr(VI), were fed to Daphnia magna. An increase of growth and fecundity were observed in the daphnids when the algae had undergone an increase of dry mass following Cr treatment, which happened in S2-N in the presence of 1 mg/liter and in S2-T in the presence of 5 mg/liter. When the algae were pretreated with 10 mg/liter, growth and fecundity were reduced in the daphnids fed on S2-N, but remained normal in the daphnids fed on S2-T. It is concluded that the tolerant strain remains a good food source even if grown in the presence of a Cr concentration that reduces the nutritional value of the normal strain.","Comparison between a normal and a Cr-tolerant strain of Scenedesmus acutus as a food source to Daphnia magna Abs: BIOSIS COPYRIGHT: BIOL ABS. A normal (S2-N) and a Cr-tolerant (S2-T) strain of Scenedesmus acutus, grown in Cr-free medium or in the presence of 1, 5, or 10 mg/liter Cr(VI), were fed to Daphnia magna. An increase of growth and fecundity were observed in the daphnids when the algae had undergone an increase of dry mass following Cr treatment, which happened in S2-N in the presence of 1 mg/liter and in S2-T in the presence of 5 mg/liter. When the algae were pretreated with 10 mg/liter, growth and fecundity were reduced in the daphnids fed on S2-N, but remained normal in the daphnids fed on S2-T. It is concluded that the tolerant strain remains a good food source even if grown in the presence of a Cr concentration that reduces the nutritional value of the normal strain."
1515335,Gopalan and  Veeramani 1994,Studies on microbial chromate reduction by Pseudomonas sp. in aerobic continuous suspended growth cultures,"BIOSIS COPYRIGHT: BIOL ABS. Reduction of hexavalent chromium was studied in three bench-scale continuous stirred tank reactors. The inoculum was a culture of Pseudomonas sp., capable of giving 83% to 87% chromate reduction in 72-h batch assays with 60 mg Cr(VI) L-1 in synthetic medium. The continuous culture studies were conducted for about 100 days using synthetic feed containing different levels of chromate (5 to 124 mg L-1) at 28ê to 30ê C and pH 6.8. The feed rate was varied over the range 0.5 to 1 L d-1 to obtain hydraulic retention time of 36 to 72 h. Chromate reduction efficiency was 81% to 91% and 100% for influent Cr(VI) concentrations of 15 to 124 and 5 mg L-1, respectively, with a hydraulic retention time of 72 h.","Studies on microbial chromate reduction by Pseudomonas sp. in aerobic continuous suspended growth cultures Abs: BIOSIS COPYRIGHT: BIOL ABS. Reduction of hexavalent chromium was studied in three bench-scale continuous stirred tank reactors. The inoculum was a culture of Pseudomonas sp., capable of giving 83% to 87% chromate reduction in 72-h batch assays with 60 mg Cr(VI) L-1 in synthetic medium. The continuous culture studies were conducted for about 100 days using synthetic feed containing different levels of chromate (5 to 124 mg L-1) at 28ê to 30ê C and pH 6.8. The feed rate was varied over the range 0.5 to 1 L d-1 to obtain hydraulic retention time of 36 to 72 h. Chromate reduction efficiency was 81% to 91% and 100% for influent Cr(VI) concentrations of 15 to 124 and 5 mg L-1, respectively, with a hydraulic retention time of 72 h."
1515302,Goh and  Chou 1998,"Bioactivity screening of Singapore gorgonians: Antimicrobial activity, toxicity to Artemia salina and efficacy against Plasmodium berghei","BIOSIS COPYRIGHT: BIOL ABS. Nine of ten gorgonian extracts from all four families tested showed antimicrobial activity. Inhibition of Gram positive bacteria was more widespread than that of Gram negative bacteria. Inhibition of the yeast Saccharomyces cerevisiae was confined to (and widespread within) the family Ellisellidae. No antifungal activity against Aspergillus sp. was found in all the extracts tested. Acute (6 hr) and chronic (24 hr) extract toxicity towards Artemia salina varied between extracts and showed no taxonomic correlations; compared to potassium dichromate, extract toxicity was low. Chronic exposure to the extracts was more effective in killing A. salina; chronic LD50 values ranged from 3.2 to 125.9 mg/ml. All ten extracts failed to extend survival, lower percentage parasitemia or affect parasite morphology in Plasmodium berghei-infected mice.","Bioactivity screening of Singapore gorgonians: Antimicrobial activity, toxicity to Artemia salina and efficacy against Plasmodium berghei Abs: BIOSIS COPYRIGHT: BIOL ABS. Nine of ten gorgonian extracts from all four families tested showed antimicrobial activity. Inhibition of Gram positive bacteria was more widespread than that of Gram negative bacteria. Inhibition of the yeast Saccharomyces cerevisiae was confined to (and widespread within) the family Ellisellidae. No antifungal activity against Aspergillus sp. was found in all the extracts tested. Acute (6 hr) and chronic (24 hr) extract toxicity towards Artemia salina varied between extracts and showed no taxonomic correlations; compared to potassium dichromate, extract toxicity was low. Chronic exposure to the extracts was more effective in killing A. salina; chronic LD50 values ranged from 3.2 to 125.9 mg/ml. All ten extracts failed to extend survival, lower percentage parasitemia or affect parasite morphology in Plasmodium berghei-infected mice."
1515297,Goeptar et al. 1995,Oxygen and xenobiotic reductase activities of cytochrome p 450,Biosis copyright: biol abs. rrm literature review mammal superoxide anion radical ferric-dioxyanion complex,Oxygen and xenobiotic reductase activities of cytochrome p 450 Abs: Biosis copyright: biol abs. rrm literature review mammal superoxide anion radical ferric-dioxyanion complex
1515295,Gloyna and  Li 1993,Supercritical water oxidation an engineering update,Biosis copyright: biol abs. rrm meeting paper wastewater treatment toxic chemicals,Supercritical water oxidation an engineering update Abs: Biosis copyright: biol abs. rrm meeting paper wastewater treatment toxic chemicals
1515290,Gill and  Pant 1987,Hematological and pathological effects of chromium toxicosis in the freshwater fish barbus-conchonius ham,Biosis copyright: biol abs. rrm water pollution erythropenia lymphocyte polycythemia gills kidney liver,Hematological and pathological effects of chromium toxicosis in the freshwater fish barbus-conchonius ham Abs: Biosis copyright: biol abs. rrm water pollution erythropenia lymphocyte polycythemia gills kidney liver
1515288,Ghose 1978,Chemical analysis of trace metals in raw sewage and treated effluent,"HEEP COPYRIGHT: BIOL ABS. Raw sewage and treated effluent samples were collected from Gangulibagan Housing Estate, Calcutta, India, at various seasons throughout the year and heavy metals were estimated with a spectrophotometer and atomic absorption spectrophotometer. The results obtained colorimetrically were comparable with the values obtained by atomic absorption spectrophotometer. B Cr(III) and Cr(IV) were estimated colorimetrically only. The concentrations of the trace metals varied slightly at different times during the year.","Chemical analysis of trace metals in raw sewage and treated effluent Abs: HEEP COPYRIGHT: BIOL ABS. Raw sewage and treated effluent samples were collected from Gangulibagan Housing Estate, Calcutta, India, at various seasons throughout the year and heavy metals were estimated with a spectrophotometer and atomic absorption spectrophotometer. The results obtained colorimetrically were comparable with the values obtained by atomic absorption spectrophotometer. B Cr(III) and Cr(IV) were estimated colorimetrically only. The concentrations of the trace metals varied slightly at different times during the year."
1515286,Geissert and  Singal 1979,"Health Hazard Evaluation Determination, Report No. HHE-77-80-620, GAF Corporation, Whitehall, Pennsylvania","An environmental and medical survey was conducted on September 14 and 15, 1977 at the GAF Corporation (SIC-3292) in Whitehall, Pennsylvania to evaluate employee exposures to asbestos (1332214), hexavalent chromium (18540299), vinyl-chloride (75014), and a variety of hydrocarbons and alcohols. The request for evaluation was made by an authorized employee representative, and subsequently by OSHA, to investigate the possible work related deaths and illnesses of 43 workers. Air samples were collected throughout the facility and tested for airborne concentrations of chemicals used in each area. Asbestos concentrations ranged from undetectable to 1.22 fibers per cubic centimeter (f/cc), which is below the OSHA standard of 2f/cc. Air contaminants at the ink mixing operations, the 9 and 12 foot printers, the resin storage and mixing operations, and the ovens were within acceptable limits. Blood tests, chest x-rays, pulmonary function tests, and a review of death certificates revealed no occupationally related illness or death. The authors conclude that, although no hazard was identified at the time of this survey, a potential asbestos exposure hazard exists in the asbestos storage and hydropulper felt mill areas, and that there is a potential short term dust exposure hazard in the ink mixing area. They recommend that exposures in each area be reduced through the use of respirators, workplace hygiene, ventilation systems, and periodic medical monitoring.","Health Hazard Evaluation Determination, Report No. HHE-77-80-620, GAF Corporation, Whitehall, Pennsylvania Abs: An environmental and medical survey was conducted on September 14 and 15, 1977 at the GAF Corporation (SIC-3292) in Whitehall, Pennsylvania to evaluate employee exposures to asbestos (1332214), hexavalent chromium (18540299), vinyl-chloride (75014), and a variety of hydrocarbons and alcohols. The request for evaluation was made by an authorized employee representative, and subsequently by OSHA, to investigate the possible work related deaths and illnesses of 43 workers. Air samples were collected throughout the facility and tested for airborne concentrations of chemicals used in each area. Asbestos concentrations ranged from undetectable to 1.22 fibers per cubic centimeter (f/cc), which is below the OSHA standard of 2f/cc. Air contaminants at the ink mixing operations, the 9 and 12 foot printers, the resin storage and mixing operations, and the ovens were within acceptable limits. Blood tests, chest x-rays, pulmonary function tests, and a review of death certificates revealed no occupationally related illness or death. The authors conclude that, although no hazard was identified at the time of this survey, a potential asbestos exposure hazard exists in the asbestos storage and hydropulper felt mill areas, and that there is a potential short term dust exposure hazard in the ink mixing area. They recommend that exposures in each area be reduced through the use of respirators, workplace hygiene, ventilation systems, and periodic medical monitoring."
1515260,Geis and  Sonzogni 1995,"Comparative acute toxicity of a synthetic mine effluent to Ceriodaphnia dubia, larval fathead minnow and the freshwater mussel Anodonta imbecilis. AU - MASNADO RG","BIOSIS COPYRIGHT: BIOL ABS. To determine if water quality-based effluent limitations recommended for a proposed discharger would provide adequate protection of aquatic life, site-specific acute toxicity tests were performed. The proposed discharger studied was a mine to be located in northern Wisconsin. The mine's discharge would flow into the Flambeau River, a relatively pristine river that harbors endangered freshwater mussels. The toxicity effects of synthetic effluents, representing a mixture of five different metals under contrasting conditions of hardness, were tested on several different organisms. Results indicated that Ceriodaphnia dubia exhibited a much greater sensitivity to various mixtures of cadmium, hexavalent chromium, copper, nickel, and zinc than did either larval fathead minnows (Pimephales promelas) or the freshwater mussel Anodonta imbecilis. Mixtures of metals at the permitted discharge levels of individual metals were also found to be consistently toxic to C. dubia. Because","Comparative acute toxicity of a synthetic mine effluent to Ceriodaphnia dubia, larval fathead minnow and the freshwater mussel Anodonta imbecilis. AU - MASNADO RG Abs: BIOSIS COPYRIGHT: BIOL ABS. To determine if water quality-based effluent limitations recommended for a proposed discharger would provide adequate protection of aquatic life, site-specific acute toxicity tests were performed. The proposed discharger studied was a mine to be located in northern Wisconsin. The mine's discharge would flow into the Flambeau River, a relatively pristine river that harbors endangered freshwater mussels. The toxicity effects of synthetic effluents, representing a mixture of five different metals under contrasting conditions of hardness, were tested on several different organisms. Results indicated that Ceriodaphnia dubia exhibited a much greater sensitivity to various mixtures of cadmium, hexavalent chromium, copper, nickel, and zinc than did either larval fathead minnows (Pimephales promelas) or the freshwater mussel Anodonta imbecilis. Mixtures of metals at the permitted discharge levels of individual metals were also found to be consistently toxic to C. dubia. Because"
1515259,Ge et al. 1992,Use of Overoxidised Polypyrrole as a Chromium(VI) Sensor,"A new polypyrrole based hexavalent chromium (7440473) (Cr+6) sensor was developed. The sensor consisted of a layer of polypyrrole galvanostatically deposited on a gold electrode. The coating was then oxidized voltammetrically by scanning between -0.4 and 1.3 volts (V) using a silver/silver-chloride electrode as the reference electrode. When the electrode was immersed in a solution containing 100 parts per billion (ppb) Cr+6 in 0.01 molar (M) sulfuric-acid, application of an anodic potential of 0.80V preconcentrated Cr+6 on the surface. A calibration plot was linear over the range 0 to 100ppb Cr+6. A freshly prepared sensor had a detection limit of 10ppb. After use, a memory response due to preconcentrated Cr+6 that was adsorbed on the polymer membrane was observed when the electrode was immersed in a blank. The memory effect could be partially eliminated by soaking and washing the electrode in water and 0.01M sulfuric-acid. The detection limit of 10ppb could be obtained with used sensors after the rinsing and washing procedure. Because of the memory problem, a more realistic detection limit was taken to be 20ppb. The authors conclude that the sensor can detect Cr+6 with a sensitivity of 20ppb. Freshly prepared sensors can detect 10ppb Cr+6.","Use of Overoxidised Polypyrrole as a Chromium(VI) Sensor Abs: A new polypyrrole based hexavalent chromium (7440473) (Cr+6) sensor was developed. The sensor consisted of a layer of polypyrrole galvanostatically deposited on a gold electrode. The coating was then oxidized voltammetrically by scanning between -0.4 and 1.3 volts (V) using a silver/silver-chloride electrode as the reference electrode. When the electrode was immersed in a solution containing 100 parts per billion (ppb) Cr+6 in 0.01 molar (M) sulfuric-acid, application of an anodic potential of 0.80V preconcentrated Cr+6 on the surface. A calibration plot was linear over the range 0 to 100ppb Cr+6. A freshly prepared sensor had a detection limit of 10ppb. After use, a memory response due to preconcentrated Cr+6 that was adsorbed on the polymer membrane was observed when the electrode was immersed in a blank. The memory effect could be partially eliminated by soaking and washing the electrode in water and 0.01M sulfuric-acid. The detection limit of 10ppb could be obtained with used sensors after the rinsing and washing procedure. Because of the memory problem, a more realistic detection limit was taken to be 20ppb. The authors conclude that the sensor can detect Cr+6 with a sensitivity of 20ppb. Freshly prepared sensors can detect 10ppb Cr+6."
1515256,Gastaud 1978,Fixation and intra cellular activities of pollutants,Heep copyright: biol abs. pesticides heavy metals carcinogenesis,Fixation and intra cellular activities of pollutants Abs: Heep copyright: biol abs. pesticides heavy metals carcinogenesis
1515250,Garmann and  Gollnick 1995,Immunophenotyping of the cellular infiltrate in the early elicitation phase of contact dermatitis in the skin of presensitized atopic individuals,"BIOSIS COPYRIGHT: BIOL ABS. Little is known about the composition of the cellular infiltrate in the early elicitation phase of contact allergy in atopic individuals. Therefore, we rechallenged ten presensitized disease-free atopic volunteers with their known contact allergen and performed biopsies at time 0 and after 6 and 24 h. Ten patients with acute exacerbated atopic dermatitis in the early stage were chosen as a control group. Skin biopsy specimens were processed for immunohistochemistry (APAAP) and evaluated by computer-assisted morphometry. CD4+ and CD45R0+ cells were found to be significantly increased after 6 (t6) and 24 h (t24), and this was accompanied by an enhanced TCR alpha/beta receptor expression at t6-CD450+ cells showed a marked influx into the epidermis at t24. CD8+ cells infiltrated the basal layer of the epidermis, thus changing the CD48 ratio from 4.6:1 at t0 to 2.2:1 at t6. CD1a+ epidermal dendritic cells increased significantly from 811 | 240/mm2 at t0, to 1210 | 333/mm2 a","Immunophenotyping of the cellular infiltrate in the early elicitation phase of contact dermatitis in the skin of presensitized atopic individuals Abs: BIOSIS COPYRIGHT: BIOL ABS. Little is known about the composition of the cellular infiltrate in the early elicitation phase of contact allergy in atopic individuals. Therefore, we rechallenged ten presensitized disease-free atopic volunteers with their known contact allergen and performed biopsies at time 0 and after 6 and 24 h. Ten patients with acute exacerbated atopic dermatitis in the early stage were chosen as a control group. Skin biopsy specimens were processed for immunohistochemistry (APAAP) and evaluated by computer-assisted morphometry. CD4+ and CD45R0+ cells were found to be significantly increased after 6 (t6) and 24 h (t24), and this was accompanied by an enhanced TCR alpha/beta receptor expression at t6-CD450+ cells showed a marked influx into the epidermis at t24. CD8+ cells infiltrated the basal layer of the epidermis, thus changing the CD48 ratio from 4.6:1 at t0 to 2.2:1 at t6. CD1a+ epidermal dendritic cells increased significantly from 811 | 240/mm2 at t0, to 1210 | 333/mm2 a"
1515248,Garg et al. 1994,Chromium (VI) induced morphological changes in Limnanthemum cristatum Griseb.: A possible bioindicator,"BIOSIS COPYRIGHT: BIOL ABS. Effects of five heavy metals viz. Cr, Cd, Cu, Ni, Pb and Zn (1 ppm) on morphological characters of Limnanthemum cristatum have been studied. Significant morphological change was the production of stunted, brown-coloured roots by chromium-treated excised leaves in contrast the control in which thin, elongated green-coloured roots were formed. During chromium treatment, juvenile leaves produced on the excised leaves showed brown colouration in the hydathodes at 226 mug/g Cr dry wt. leaf tissue concentration. However, no colouration was found in the juvenile leaves produced in the cultures containing metals other than chromium as well as in control. Characteristic ultrastructural changes observed in the juvenile leaf at 1 ppm Cr are: (1) heavily packed starch grains, (ii) irregular nucleus in the root, (iii) disorganised plastids; (iv) retracted plasma membrane, and (v) thickening in the tracheids near hydathodes.","Chromium (VI) induced morphological changes in Limnanthemum cristatum Griseb.: A possible bioindicator Abs: BIOSIS COPYRIGHT: BIOL ABS. Effects of five heavy metals viz. Cr, Cd, Cu, Ni, Pb and Zn (1 ppm) on morphological characters of Limnanthemum cristatum have been studied. Significant morphological change was the production of stunted, brown-coloured roots by chromium-treated excised leaves in contrast the control in which thin, elongated green-coloured roots were formed. During chromium treatment, juvenile leaves produced on the excised leaves showed brown colouration in the hydathodes at 226 mug/g Cr dry wt. leaf tissue concentration. However, no colouration was found in the juvenile leaves produced in the cultures containing metals other than chromium as well as in control. Characteristic ultrastructural changes observed in the juvenile leaf at 1 ppm Cr are: (1) heavily packed starch grains, (ii) irregular nucleus in the root, (iii) disorganised plastids; (iv) retracted plasma membrane, and (v) thickening in the tracheids near hydathodes."
1515246,Gardea-Torresdey et al. 1998,"Phytofiltration of hazardous cadmium, chromium, lead and zinc ions by biomass of Medicago sativa (Alfalfa)","BIOSIS COPYRIGHT: BIOL ABS. Previous laboratory batch experiments of Medicago sativa (Alfalfa) indicated that the African shoots population had an appreciable ability to bind copper(II) and nickel(II) ions from aqueous solution. Batch laboratory pH profile, time dependency and capacity experiments were performed to determine the binding ability of the African shoots for cadmium(II), chromium(III), chromium(VI), lead(II), and zinc(II). Batch pH profile experiments for the mentioned ions indicated that the optimum pH for metal binding is approximately 5.0. Time dependency experiments for all the metals studied showed that metal binding to the African alfalfa shoots occurred within 5 min. Binding capacity experiments revealed the following amounts of metal ions bound per gram of biomass: 7.1 mg Cd(II), 7.7 mg Cr(III), 43 mg Pb(II), and 4.9 mg Zn(II). However, no binding occurred for chromium(VI). Nearly all of the metals studied were recoverable by treatment with 0.1 M HCl. Column experiments were pe","Phytofiltration of hazardous cadmium, chromium, lead and zinc ions by biomass of Medicago sativa (Alfalfa) Abs: BIOSIS COPYRIGHT: BIOL ABS. Previous laboratory batch experiments of Medicago sativa (Alfalfa) indicated that the African shoots population had an appreciable ability to bind copper(II) and nickel(II) ions from aqueous solution. Batch laboratory pH profile, time dependency and capacity experiments were performed to determine the binding ability of the African shoots for cadmium(II), chromium(III), chromium(VI), lead(II), and zinc(II). Batch pH profile experiments for the mentioned ions indicated that the optimum pH for metal binding is approximately 5.0. Time dependency experiments for all the metals studied showed that metal binding to the African alfalfa shoots occurred within 5 min. Binding capacity experiments revealed the following amounts of metal ions bound per gram of biomass: 7.1 mg Cd(II), 7.7 mg Cr(III), 43 mg Pb(II), and 4.9 mg Zn(II). However, no binding occurred for chromium(VI). Nearly all of the metals studied were recoverable by treatment with 0.1 M HCl. Column experiments were pe"
1515244,Gao et al. 1993,Simultaneous determination of hexavalent and total chromium in water and plating baths by spectrophotometry,"BIOSIS COPYRIGHT: BIOL ABS. A new spectrophotometric determination method of hexavalent chromium in waste water and plating baths is described based on the oxidation of beryllon III by chromium(VI) in 0.02M sulphuric acid medium. The decrease in the absorbance of beryllon III was measured at 482 nm with an apparent molar absorptivity of 5.15aw was obeyed for chromium(VI) over the range 0-25 mug/25 ml. After the oxidation of Cr(III) to Cr(VI) by ammonium persulphate, total chromium can be determined. Therefore, chromium(III) can be calculated by subtracting chromium(VI) from total chromium. The detection limit is 0.015 and 0.020 mug/25 ml for chromium(VI) and total chromium, respectively. A sensitive spectrophotometric method for trace Cr(III) and Cr(VI) in waste water and plating baths was developed with good precision and accuracy. The reaction is also discussed.","Simultaneous determination of hexavalent and total chromium in water and plating baths by spectrophotometry Abs: BIOSIS COPYRIGHT: BIOL ABS. A new spectrophotometric determination method of hexavalent chromium in waste water and plating baths is described based on the oxidation of beryllon III by chromium(VI) in 0.02M sulphuric acid medium. The decrease in the absorbance of beryllon III was measured at 482 nm with an apparent molar absorptivity of 5.15aw was obeyed for chromium(VI) over the range 0-25 mug/25 ml. After the oxidation of Cr(III) to Cr(VI) by ammonium persulphate, total chromium can be determined. Therefore, chromium(III) can be calculated by subtracting chromium(VI) from total chromium. The detection limit is 0.015 and 0.020 mug/25 ml for chromium(VI) and total chromium, respectively. A sensitive spectrophotometric method for trace Cr(III) and Cr(VI) in waste water and plating baths was developed with good precision and accuracy. The reaction is also discussed."
1515215,Gao et al. 1996,A new concentration and determination method of hexavalent chromium in water by an organic solvent-soluble membrane filter,Biosis copyright: biol abs. rrm research article chromiumvi detection limit environmental analysis analytical method,A new concentration and determination method of hexavalent chromium in water by an organic solvent-soluble membrane filter Abs: Biosis copyright: biol abs. rrm research article chromiumvi detection limit environmental analysis analytical method
1515213,Gammelgaard et al. 1997,Improvement of simultaneous determination of chromium species in aqueous solution by ion chromatography and chemiluminescence detection,"BIOSIS COPYRIGHT: BIOL ABS. A sensitive method for the simultaneous determination of chromium(III) and chromium(VI) was developed using ion chromatography and chemiluminescence detection. Two Dionex ion-exchange guard columns in series, CG5 and AG7. were used to separate chromium(III) from chromium(VI). Chromium(VI) was reduced by potassium sulphite. whereupon both species were detected by use of the luminol-hydrogen peroxide chemiluminescence system. Parameters affecting retention times and resolution of the separator columns, such as eluent pH, eluent composition, reductant pH and concentration, and flow rates were optimized. Furthermore, the stabilities of reductant and luminol solutions were studied. The linear range of the calibration curve for chromium(III) and chromium(VI) was 1-400 mug l-1. The detection limit was 0.12 mug l-1 for chromium(III) and 0.09 mug l-1 for chromium(VI), respectively. The precision at the 20 mug l-1 level was 1.4% for chromium(III) and 2.5% for chromium(VI), respe","Improvement of simultaneous determination of chromium species in aqueous solution by ion chromatography and chemiluminescence detection Abs: BIOSIS COPYRIGHT: BIOL ABS. A sensitive method for the simultaneous determination of chromium(III) and chromium(VI) was developed using ion chromatography and chemiluminescence detection. Two Dionex ion-exchange guard columns in series, CG5 and AG7. were used to separate chromium(III) from chromium(VI). Chromium(VI) was reduced by potassium sulphite. whereupon both species were detected by use of the luminol-hydrogen peroxide chemiluminescence system. Parameters affecting retention times and resolution of the separator columns, such as eluent pH, eluent composition, reductant pH and concentration, and flow rates were optimized. Furthermore, the stabilities of reductant and luminol solutions were studied. The linear range of the calibration curve for chromium(III) and chromium(VI) was 1-400 mug l-1. The detection limit was 0.12 mug l-1 for chromium(III) and 0.09 mug l-1 for chromium(VI), respectively. The precision at the 20 mug l-1 level was 1.4% for chromium(III) and 2.5% for chromium(VI), respe"
1515208,Gajghate et al. 1992,Removal of chromium(VI) as chromium diphenyl carbazide (CDC) complex from aqueous solution by activated carbon,"BIOSIS COPYRIGHT: BIOL ABS. Adsorption of Cr (VI) as CDC-complex from aqueous solution by activated C has been investigated. Factors like pH and presence of Cr (III) which affect the adsorption of CDC-complex were studied. The increase in particle size and surface area of activated C does not enhance the removal of CDC-complex. For different concentrations of Cr, the optimum quantity of Diphenyl Carbazide has been determined. The reduced Cr e.g. Cr (III) decreases the CDC-complex removal. The Langmuir and Freundlich isotherms constant as calculated are GAMMAm = 1.8932 and b = 0.2305 and n = 0.036, log K = 0.0266, respectively.","Removal of chromium(VI) as chromium diphenyl carbazide (CDC) complex from aqueous solution by activated carbon Abs: BIOSIS COPYRIGHT: BIOL ABS. Adsorption of Cr (VI) as CDC-complex from aqueous solution by activated C has been investigated. Factors like pH and presence of Cr (III) which affect the adsorption of CDC-complex were studied. The increase in particle size and surface area of activated C does not enhance the removal of CDC-complex. For different concentrations of Cr, the optimum quantity of Diphenyl Carbazide has been determined. The reduced Cr e.g. Cr (III) decreases the CDC-complex removal. The Langmuir and Freundlich isotherms constant as calculated are GAMMAm = 1.8932 and b = 0.2305 and n = 0.036, log K = 0.0266, respectively."
1515205,Gaballah et al. 1994,Decontamination of industrial effluents for environmental protection and recycling of metals,"BIOSIS COPYRIGHT: BIOL ABS. The electroplating industries generate large volumes of industrial effluent containing hexavalent chromium ions. The classical treatment of these effluents is via the reduction of Cr6+ to Cr3+ before precipitation. This produces a significant amount of calcium sulfate and chromium hydroxide. Due to environmental regulations, high waste disposal costs and the necessity to recycle these heavy cations, research on a new approach has been initiated. This paper describes the preliminary results of a low cost process dedicated to the decontamination of these industrial effluents by chemically treated barks. Decontamination of solutions containing hexavalent chromium by this organic support has been studied on the laboratory scale. Experiments conducted with the main European tree species have shown that the metal removal percentage, from synthetic solutions, depends upon pH, initial concentrations and the tree species. More than 95% of Cr6+, contained in a 10, 100 or 1000 ppm","Decontamination of industrial effluents for environmental protection and recycling of metals Abs: BIOSIS COPYRIGHT: BIOL ABS. The electroplating industries generate large volumes of industrial effluent containing hexavalent chromium ions. The classical treatment of these effluents is via the reduction of Cr6+ to Cr3+ before precipitation. This produces a significant amount of calcium sulfate and chromium hydroxide. Due to environmental regulations, high waste disposal costs and the necessity to recycle these heavy cations, research on a new approach has been initiated. This paper describes the preliminary results of a low cost process dedicated to the decontamination of these industrial effluents by chemically treated barks. Decontamination of solutions containing hexavalent chromium by this organic support has been studied on the laboratory scale. Experiments conducted with the main European tree species have shown that the metal removal percentage, from synthetic solutions, depends upon pH, initial concentrations and the tree species. More than 95% of Cr6+, contained in a 10, 100 or 1000 ppm"
1515204,Furtmann and  Seifert 1990,On the routine determination of chromium-vi in soils,Biosis copyright: biol abs. rrm environmental toxicology sewage spectrophotometry,On the routine determination of chromium-vi in soils Abs: Biosis copyright: biol abs. rrm environmental toxicology sewage spectrophotometry
1515202,Fuoco and  Papoff 1975,"Individual detection and determination of chromium(VI) and chromium(III) together with Cu, Pb, Cd, Ni and Zn in tap water at ppb level","HEEP COPYRIGHT: BIOL ABS. The poisoning effect of Cr depends upon its valence state in the sample. To detect Cr(VI) and CR(III) in trace quantities in tap water, the behavior of these ions was investigated by differential pulse polarography and differential anodic stripping polarography in ammonia buffer solutions at very low Cr concentration. In the concentration range used (up to 10-5 M) Cr(VI) is reduced to Cr(O) via Cr(III) and Cr(II). In 0.1 M NH4OH and 0.05 M NH4Cl, the peak potentials related to the 3 steps are -0.30, -1.40 and -1.59 V, respectively. The concentration of Cr(VI) and Cr(III) in the sample can be calculated by the height of the 1st and 3rd peaks. By considering that the electrochemical production of Cr(II) on the electrode should give rise to a precipitate of Cr(OH)2 in situ, differential anodic stripping experiments were performed. If the pre-electrolysis potential is properly chosen, then an anodic peak for Cr(II) oxidation to Cr(III) is obtained. The corresponding peak height vs. concentration plot is linear down to 6.6 The values of the minimum detectable concentration of the other metal ions which can be determined together with Cr, with or without interference, are reported.","Individual detection and determination of chromium(VI) and chromium(III) together with Cu, Pb, Cd, Ni and Zn in tap water at ppb level Abs: HEEP COPYRIGHT: BIOL ABS. The poisoning effect of Cr depends upon its valence state in the sample. To detect Cr(VI) and CR(III) in trace quantities in tap water, the behavior of these ions was investigated by differential pulse polarography and differential anodic stripping polarography in ammonia buffer solutions at very low Cr concentration. In the concentration range used (up to 10-5 M) Cr(VI) is reduced to Cr(O) via Cr(III) and Cr(II). In 0.1 M NH4OH and 0.05 M NH4Cl, the peak potentials related to the 3 steps are -0.30, -1.40 and -1.59 V, respectively. The concentration of Cr(VI) and Cr(III) in the sample can be calculated by the height of the 1st and 3rd peaks. By considering that the electrochemical production of Cr(II) on the electrode should give rise to a precipitate of Cr(OH)2 in situ, differential anodic stripping experiments were performed. If the pre-electrolysis potential is properly chosen, then an anodic peak for Cr(II) oxidation to Cr(III) is obtained. The corresponding peak height vs. concentration plot is linear down to 6.6 The values of the minimum detectable concentration of the other metal ions which can be determined together with Cr, with or without interference, are reported."
1515199,Fujii et al. 1990,Bacterial reduction of toxic hexavalent chromium using a fed-batch culture of Enterobacter cloacae strain HO1,"BIOSIS COPYRIGHT: BIOL ABS. Bacterial reduction of hexavalent chromium (chromate: CrO42-) was investigated using fed-batch cultures of Enterobacter cloacae strain HOI. In the fed-batch cultures, toxic CrO42- was continuously added in small doses to minimize the toxic effect. The fed-batch process was proved to be an effective biological method for detoxifying CrO42- in aqueous solutions.","Bacterial reduction of toxic hexavalent chromium using a fed-batch culture of Enterobacter cloacae strain HO1 Abs: BIOSIS COPYRIGHT: BIOL ABS. Bacterial reduction of hexavalent chromium (chromate: CrO42-) was investigated using fed-batch cultures of Enterobacter cloacae strain HOI. In the fed-batch cultures, toxic CrO42- was continuously added in small doses to minimize the toxic effect. The fed-batch process was proved to be an effective biological method for detoxifying CrO42- in aqueous solutions."
1515175,Fujie et al. 1994,Development of a bioreactor system for the treatment of chromate wastewater using enterobacter cloacae ho1,Biosis copyright: biol abs. rrm research article enterobacter-cloacae hexavalent chromium organic pollutant chromium hydroxide oxidation-reduction potential toxicity mutagenicity,Development of a bioreactor system for the treatment of chromate wastewater using enterobacter cloacae ho1 Abs: Biosis copyright: biol abs. rrm research article enterobacter-cloacae hexavalent chromium organic pollutant chromium hydroxide oxidation-reduction potential toxicity mutagenicity
1515173,Fude and  Liu 1993,Microbial removal and recovery of chromium(VI) from electroplating wastewater,BIOSIS COPYRIGHT: BIOL ABS. Chromate resistance of Desulfovibrio sp. SRI was isolated from chromium-contaminated sludge in electroplating plants. The bench-scale and the mediated studies on the utilization of strain SRI for removal of Cr (VI) from electroplating wastewater have been explored. Included are the studies aimed at elucidating the basic mechanism and the optimum conditions of Cr (VI) removal. Process development efforts for the use to treat the wastewater showed that about 99.7% of the total chromium could be removed and more than 80% of chromium recovered by the described method.,Microbial removal and recovery of chromium(VI) from electroplating wastewater Abs: BIOSIS COPYRIGHT: BIOL ABS. Chromate resistance of Desulfovibrio sp. SRI was isolated from chromium-contaminated sludge in electroplating plants. The bench-scale and the mediated studies on the utilization of strain SRI for removal of Cr (VI) from electroplating wastewater have been explored. Included are the studies aimed at elucidating the basic mechanism and the optimum conditions of Cr (VI) removal. Process development efforts for the use to treat the wastewater showed that about 99.7% of the total chromium could be removed and more than 80% of chromium recovered by the described method.
1515170,Fude et al. 1994,Reduction of Cr(VI) by a consortium of sulfate-reducing bacteria (SRB III),"BIOSIS COPYRIGHT: BIOL ABS. A consortium of bacteria with tolerance to high concentrations of Cr(VI) (up to 2,500 ppm) and other toxic heavy metals has been obtained from metal-refinishing wastewaters in Chengdu, People's Republic of China. This consortium consists of a range of gram-positive and gram-negative rods and has the capacity to reduce Cr(VI) to Cr(III) as amorphous precipitates which are associated with the bacterial surfaces. An endospore-producing, gram-positive rod and a gram-negative rod accumulate the most metallic precipitates, and, over time, 80 to 95% of Cr can be removed from concentrations ranging from 50 to 2,000 ppm (0.96 to 38.45 mM). Kinetic studies revealed a first-order constant for Cr removal of 0.1518 h-1 for an initial concentration of 1,000 ppm (19.3 mM), and the sorption isothermal data could be interpreted by the Freundlich relationship. The sorption was not entirely due to a passive interaction with reactive sites on the bacterial surfaces since gamma-irradiated","Reduction of Cr(VI) by a consortium of sulfate-reducing bacteria (SRB III) Abs: BIOSIS COPYRIGHT: BIOL ABS. A consortium of bacteria with tolerance to high concentrations of Cr(VI) (up to 2,500 ppm) and other toxic heavy metals has been obtained from metal-refinishing wastewaters in Chengdu, People's Republic of China. This consortium consists of a range of gram-positive and gram-negative rods and has the capacity to reduce Cr(VI) to Cr(III) as amorphous precipitates which are associated with the bacterial surfaces. An endospore-producing, gram-positive rod and a gram-negative rod accumulate the most metallic precipitates, and, over time, 80 to 95% of Cr can be removed from concentrations ranging from 50 to 2,000 ppm (0.96 to 38.45 mM). Kinetic studies revealed a first-order constant for Cr removal of 0.1518 h-1 for an initial concentration of 1,000 ppm (19.3 mM), and the sorption isothermal data could be interpreted by the Freundlich relationship. The sorption was not entirely due to a passive interaction with reactive sites on the bacterial surfaces since gamma-irradiated"
1515169,Frohberg 1971,Contribution to the Study of the Extrapolation of the Results of AnimalExperiments to Man,"The author begins by reviewing the various factors which have a bearing on the results of animal experiments (concentration of the substance investigated, method of application, type of animal, metabolic behavior of the substance, experimental conditions, etc.). Experience shows that not all substances which cause malignant tumors in animals are carcinogenic in man. Results obtained with animals and humans are compared for nine substances recognized as being carcinogenic: arsenic, asbestos, benzene, beryllium, tri and hexavalent chromium compounds, nickel and its inorganic compounds, 2-naphthylamine, 4-aminodiphenyl, and benzidine. The findings of different research workers are summarized in tables. In conclusion, the results are reported of investigations into the metabolism of 2-naphthylamine, which show that carcinogenicity tests should as far as possible be carried out on types of animal which absorb, metabolize and excrete the substances investigated in the same way as humans.","Contribution to the Study of the Extrapolation of the Results of AnimalExperiments to Man Abs: The author begins by reviewing the various factors which have a bearing on the results of animal experiments (concentration of the substance investigated, method of application, type of animal, metabolic behavior of the substance, experimental conditions, etc.). Experience shows that not all substances which cause malignant tumors in animals are carcinogenic in man. Results obtained with animals and humans are compared for nine substances recognized as being carcinogenic: arsenic, asbestos, benzene, beryllium, tri and hexavalent chromium compounds, nickel and its inorganic compounds, 2-naphthylamine, 4-aminodiphenyl, and benzidine. The findings of different research workers are summarized in tables. In conclusion, the results are reported of investigations into the metabolism of 2-naphthylamine, which show that carcinogenicity tests should as far as possible be carried out on types of animal which absorb, metabolize and excrete the substances investigated in the same way as humans."
1515168,Frey et al. 1983,Sensitivity of estuarine phytoplankton to hexavalent chromium,"HEEP COPYRIGHT: BIOL ABS. The effects of hexavalent Cr on both natural assemblages of phytoplankton and cultures of Thalassiosira pseudonana clone 3H were tested. Water was collected from various locations in Yaquina Bay, Oregon (USA), with salinities ranging from 32.5 to 0.03 . A variety of nutrient regimes were tested by adding major nutrients and micronutrients and/or stripping micronutrients with activated C. In one high salinity experiment, Cr was stimulatory, as were micronutrient additions. In other high and medium salinity experiments, Cr was neither stimulatory nor inhibitory, at levels up to 1.9 mumol l-1 Cr. There was slight inhibition of growth at 19.0 mumol l-1 Cr, due specifically to inhibition of Skeletonema costatum. In freshwater experiments, Cr was very inhibitory at 1.9 mumol l-1 Cr, and slightly inhibitory at 0.19 mumol l-1 Cr. Species inhibited by Cr were Surirella ovata, Detonula confervacea and Cyclotella sp. Experiments were conducted with T. pseudonana grown over a wide range of salinities. Cr was very inhibitory in fresh water and became progressively less toxic as the salinity increased. Most inhibition was neutralized by a salinity of 2.1 .","Sensitivity of estuarine phytoplankton to hexavalent chromium Abs: HEEP COPYRIGHT: BIOL ABS. The effects of hexavalent Cr on both natural assemblages of phytoplankton and cultures of Thalassiosira pseudonana clone 3H were tested. Water was collected from various locations in Yaquina Bay, Oregon (USA), with salinities ranging from 32.5 to 0.03 . A variety of nutrient regimes were tested by adding major nutrients and micronutrients and/or stripping micronutrients with activated C. In one high salinity experiment, Cr was stimulatory, as were micronutrient additions. In other high and medium salinity experiments, Cr was neither stimulatory nor inhibitory, at levels up to 1.9 mumol l-1 Cr. There was slight inhibition of growth at 19.0 mumol l-1 Cr, due specifically to inhibition of Skeletonema costatum. In freshwater experiments, Cr was very inhibitory at 1.9 mumol l-1 Cr, and slightly inhibitory at 0.19 mumol l-1 Cr. Species inhibited by Cr were Surirella ovata, Detonula confervacea and Cyclotella sp. Experiments were conducted with T. pseudonana grown over a wide range of salinities. Cr was very inhibitory in fresh water and became progressively less toxic as the salinity increased. Most inhibition was neutralized by a salinity of 2.1 ."
1515165,Frenzel 1998,Highly sensitive semi-quantitative field test for the determination of chromium (VI) in aqueous samples,"BIOSIS COPYRIGHT: BIOL ABS. A method for the semi-quantitative colorimetric determination of chromium(VI) at sub mug levels after sorptive preconcentration is presented. The method is based on the retention of the reaction product (preformed in liquid phase) between Cr(VI) and diphenylcarbazide on membrane embedded cation exchange material. The color intensity of the membrane can be correlated to Cr(VI) concentrations in the range 0.05-50 mug/L (i.e. almost three orders of magnitude lower than the conventional spectrophotometric procedure) with a detection limit of about 10 ng/L (using 50 mL of sample volume). Due to the visual inspection mode and comparative color detection the precision is only 30-80% rsd which, however, is regarded as sufficient for screening purposes. Analysis of real samples including different kinds of waters and extracts of soil and filter collected airborne particulate matter demonstrated the applicability of the method for fast and species selective screening. Recovery e","Highly sensitive semi-quantitative field test for the determination of chromium (VI) in aqueous samples Abs: BIOSIS COPYRIGHT: BIOL ABS. A method for the semi-quantitative colorimetric determination of chromium(VI) at sub mug levels after sorptive preconcentration is presented. The method is based on the retention of the reaction product (preformed in liquid phase) between Cr(VI) and diphenylcarbazide on membrane embedded cation exchange material. The color intensity of the membrane can be correlated to Cr(VI) concentrations in the range 0.05-50 mug/L (i.e. almost three orders of magnitude lower than the conventional spectrophotometric procedure) with a detection limit of about 10 ng/L (using 50 mL of sample volume). Due to the visual inspection mode and comparative color detection the precision is only 30-80% rsd which, however, is regarded as sufficient for screening purposes. Analysis of real samples including different kinds of waters and extracts of soil and filter collected airborne particulate matter demonstrated the applicability of the method for fast and species selective screening. Recovery e"
1515162,Freeman 1993,"Prognosis of Occupational Contact Dermatitis in New South Wales, Australia AU - Rosen RH","A study of the prognosis of occupational contact dermatitis (OCD) in Australian workers was conducted. The study group consisted of 570 patients who were diagnosed with OCD at the Skin and Cancer Foundation in Sydney between 1984 and 1990. They were contacted 1 to 5 years after the original diagnosis and asked to complete a series of questionnaires requesting information on their current condition, present occupation, and whether their condition had required them to modify their work tasks or to change jobs. Responses were received from 334 persons who had been employed as hairdressers or in food handling, construction, and medical jobs. Overall, 33.5% of the patients reported that their dermatitis had healed, 36.8% reported improvements 24.9% reported no change in their condition, 4.2% had become worse, and 0.6% reported being unable to work because of their condition. By occupation, at least 70% of the subjects employed in hairdressing, food handling, and medical jobs reported their condition had healed or improved. Only 45% of the construction workers reported any improvement. Approximately 51% of the construction workers reported their condition unchanged. The prognosis did not differ significantly between those who had been diagnosed with allergic or irritant contact dermatitis. Workers whose OCD was due to exposures commonly occurring in the construction industry, potassium-dichromate (7778509) and cobalt-chloride (7646799), had the worst prognosis. Except in the construction industry, changing jobs or leaving the industry altogether resulted in a more favorable prognosis than remaining in the original job. The greatest improvement occurred when the worker left the industry entirely. Atopic patients showed a poorer healing and improvement rate than nonatopic subjects, 62.4 versus 79%. The authors conclude that changing work duties or leaving the work environment altogether improves the prognosis for OCD.","Prognosis of Occupational Contact Dermatitis in New South Wales, Australia AU - Rosen RH Abs: A study of the prognosis of occupational contact dermatitis (OCD) in Australian workers was conducted. The study group consisted of 570 patients who were diagnosed with OCD at the Skin and Cancer Foundation in Sydney between 1984 and 1990. They were contacted 1 to 5 years after the original diagnosis and asked to complete a series of questionnaires requesting information on their current condition, present occupation, and whether their condition had required them to modify their work tasks or to change jobs. Responses were received from 334 persons who had been employed as hairdressers or in food handling, construction, and medical jobs. Overall, 33.5% of the patients reported that their dermatitis had healed, 36.8% reported improvements 24.9% reported no change in their condition, 4.2% had become worse, and 0.6% reported being unable to work because of their condition. By occupation, at least 70% of the subjects employed in hairdressing, food handling, and medical jobs reported their condition had healed or improved. Only 45% of the construction workers reported any improvement. Approximately 51% of the construction workers reported their condition unchanged. The prognosis did not differ significantly between those who had been diagnosed with allergic or irritant contact dermatitis. Workers whose OCD was due to exposures commonly occurring in the construction industry, potassium-dichromate (7778509) and cobalt-chloride (7646799), had the worst prognosis. Except in the construction industry, changing jobs or leaving the industry altogether resulted in a more favorable prognosis than remaining in the original job. The greatest improvement occurred when the worker left the industry entirely. Atopic patients showed a poorer healing and improvement rate than nonatopic subjects, 62.4 versus 79%. The authors conclude that changing work duties or leaving the work environment altogether improves the prognosis for OCD."
1514527,Freeman et al. 1996,Chemical behavior of p s cl f and cr in borosilicate nuclear waste glasses au - feng x,Biosis copyright: biol abs. rrm meeting abstract phosphorus sulfur chlorine fluorine chromium low-level nuclear waste,Chemical behavior of p s cl f and cr in borosilicate nuclear waste glasses au - feng x Abs: Biosis copyright: biol abs. rrm meeting abstract phosphorus sulfur chlorine fluorine chromium low-level nuclear waste
1514526,Francko et al. 1993,Effect of hexavalent chromium on photosynthetic rates and petiole growth in Nelumbo lutea seedlings,"BIOSIS COPYRIGHT: BIOL ABS. Petiolar photosynthetic carbon assimilation (PCA) rates, seedling petiole length, and petiolar elongation rates were measured in Nelumbo lutea (Willd.) Pers. (American lotus) grown in aseptic liquid culture at pH 5.6 and 8.2 and exposed for 4, 48 and 96 hr to hexavalent chromium in initial concentrations varying from 0.5 to 100 mg. Within several hours considerable chromium partitioned into a phase removable from solution by filtration through 0.6-mum Nuclepore filtration. Exposure for 48 hr to soluble chromium levels as low as 0.02 mg/l in pH 5.6 media significantly stimulated PCA rates, but at pH 8.2 only plants exposed to the highest chromium concentrations for 96 hr exhibited enhanced PCA rates. The solubilizer method used for routine PCA analyses produced values that markedly overestimated net carbon fixation. Soluble hexavalent chromium concentrations of as little as 0.6 mg/l in growth media reduced mean petiole lengths in 48- and 96-hr experiments. Petiolar elong","Effect of hexavalent chromium on photosynthetic rates and petiole growth in Nelumbo lutea seedlings Abs: BIOSIS COPYRIGHT: BIOL ABS. Petiolar photosynthetic carbon assimilation (PCA) rates, seedling petiole length, and petiolar elongation rates were measured in Nelumbo lutea (Willd.) Pers. (American lotus) grown in aseptic liquid culture at pH 5.6 and 8.2 and exposed for 4, 48 and 96 hr to hexavalent chromium in initial concentrations varying from 0.5 to 100 mg. Within several hours considerable chromium partitioned into a phase removable from solution by filtration through 0.6-mum Nuclepore filtration. Exposure for 48 hr to soluble chromium levels as low as 0.02 mg/l in pH 5.6 media significantly stimulated PCA rates, but at pH 8.2 only plants exposed to the highest chromium concentrations for 96 hr exhibited enhanced PCA rates. The solubilizer method used for routine PCA analyses produced values that markedly overestimated net carbon fixation. Soluble hexavalent chromium concentrations of as little as 0.6 mg/l in growth media reduced mean petiole lengths in 48- and 96-hr experiments. Petiolar elong"
1514525,Francko et al. 1993,Effect of hexavalent chromium and dissolved humic materials on photosynthetic rates and petiole elongation in nelumbo-lutea american lotus seedlings,Biosis copyright: biol abs. rrm abstract typha leachate toxicity,Effect of hexavalent chromium and dissolved humic materials on photosynthetic rates and petiole elongation in nelumbo-lutea american lotus seedlings Abs: Biosis copyright: biol abs. rrm abstract typha leachate toxicity
1514524,Franchini et al. 1979,Update On Biological Monitoring Of Workers Occupationally Exposed To Chromium,"Data concerning the biological monitoring of workers undergoing occupational exposure to chromium (7440473) was reviewed. In 1970, industrial chromium consumption was estimated at 500,000 metric tons per year with most occupational exposures involving hexavalent chromium and resulting in local caustic effects, protein denaturation, ulcerative and allergic manifestations in the skin and respiratory tract, mutagenic or carcinogenic effects, and reversible renal tubule lesions. Due to rapid elimination and significant absorption, chromium content in the urine best reflects current exposure. The interpretation of urinary data must make allowance for the analytical method employed, the most reliable of which is atomic absorption spectrometry using a graphite tube atomizing system, bearing in mind that chromium is normally eliminated with the urine in a volume of approximately 1.8 micrograms (microg) per liter. Other factors to be considered during the interpretation of urinary data include the chemical and physical state of the metal, reflected via absorption rate, and organismic accumulation. Renal clearance permits the indirect evaluation of urinary accumulation although urinary chromium elimination determined at least 1 week after the most recent exposure provides a closer approximation since elimination values remain 10 times higher than normal only in individuals experiencing excessive accumulation and exhibiting a renal clearance rate greater than 10 milliliters per minute. The authors conclude that the establishment of acceptable exposure limits is complicated by the different chemical forms of chromium, different exposure durations, and different individual work histories. When urinary chromium elimination is measured both at the start and at the end of the work day, an increase of more than 5microg per gram of creatinine indicates a need for the improvement of working conditions, temporary worker removal from exposure, and the performance of medical examinations. Critical organs and tissues for the determination of chromium exposures include the skin and mucosa (particularly in the nasal cavity), the respiratory apparatus, and the kidneys. (Italian)","Update On Biological Monitoring Of Workers Occupationally Exposed To Chromium Abs: Data concerning the biological monitoring of workers undergoing occupational exposure to chromium (7440473) was reviewed. In 1970, industrial chromium consumption was estimated at 500,000 metric tons per year with most occupational exposures involving hexavalent chromium and resulting in local caustic effects, protein denaturation, ulcerative and allergic manifestations in the skin and respiratory tract, mutagenic or carcinogenic effects, and reversible renal tubule lesions. Due to rapid elimination and significant absorption, chromium content in the urine best reflects current exposure. The interpretation of urinary data must make allowance for the analytical method employed, the most reliable of which is atomic absorption spectrometry using a graphite tube atomizing system, bearing in mind that chromium is normally eliminated with the urine in a volume of approximately 1.8 micrograms (microg) per liter. Other factors to be considered during the interpretation of urinary data include the chemical and physical state of the metal, reflected via absorption rate, and organismic accumulation. Renal clearance permits the indirect evaluation of urinary accumulation although urinary chromium elimination determined at least 1 week after the most recent exposure provides a closer approximation since elimination values remain 10 times higher than normal only in individuals experiencing excessive accumulation and exhibiting a renal clearance rate greater than 10 milliliters per minute. The authors conclude that the establishment of acceptable exposure limits is complicated by the different chemical forms of chromium, different exposure durations, and different individual work histories. When urinary chromium elimination is measured both at the start and at the end of the work day, an increase of more than 5microg per gram of creatinine indicates a need for the improvement of working conditions, temporary worker removal from exposure, and the performance of medical examinations. Critical organs and tissues for the determination of chromium exposures include the skin and mucosa (particularly in the nasal cavity), the respiratory apparatus, and the kidneys. (Italian)"
1514522,Foussereau et al. 1982,Shoe-Makers,"Contact allergies among shoe makers were reviewed with regard to the identification and nature of the allergenic substances. A number of substances have been found to be sensitizing in shoe makers including tanning products such as hexavalent-chromium (18540299), azoic leather dyes, formaldehyde (50000) impregnating materials and antifungal powders. Resins containing condensates of formaldehyde and p-t-butylphenol (98544) (PTBP) have been found to be the major cause of allergies in shoe makers, usually as a result of the presence of uncondensed PTBP. A total of 75 out of 106 PTBP allergy cases reported in the literature were found to be occupational, the most affected occupation being shoe making with 42 cases. Cases of PTBP allergies in shoe makers have been reported in the Netherlands, Britain, Germany, France and Sweden. The majority of cases have been found to result from use of the Union Carbide resins CKR-1634 and CKR-1734. One study has shown that patients allergic to CKR-1634 are often also allergic to CKR-1734. Another study has demonstrated a reduction in the number of PTBP allergies since 1958, indicating the presence of less PTBP in the resins. A list of sensitizing resins was presented.","Shoe-Makers Abs: Contact allergies among shoe makers were reviewed with regard to the identification and nature of the allergenic substances. A number of substances have been found to be sensitizing in shoe makers including tanning products such as hexavalent-chromium (18540299), azoic leather dyes, formaldehyde (50000) impregnating materials and antifungal powders. Resins containing condensates of formaldehyde and p-t-butylphenol (98544) (PTBP) have been found to be the major cause of allergies in shoe makers, usually as a result of the presence of uncondensed PTBP. A total of 75 out of 106 PTBP allergy cases reported in the literature were found to be occupational, the most affected occupation being shoe making with 42 cases. Cases of PTBP allergies in shoe makers have been reported in the Netherlands, Britain, Germany, France and Sweden. The majority of cases have been found to result from use of the Union Carbide resins CKR-1634 and CKR-1734. One study has shown that patients allergic to CKR-1634 are often also allergic to CKR-1734. Another study has demonstrated a reduction in the number of PTBP allergies since 1958, indicating the presence of less PTBP in the resins. A list of sensitizing resins was presented."
1514521,Foussereau et al. 1982,Metallurgy,"Job related contact allergies were reviewed in metallurgy workers including smelters, machine tool workers, welders, metal bonders and galvanized sheet metal warehousemen. The primary allergens affecting smelters were considered: hexavalent-chromium (18540299), phenoplastic resins and other allergens such as Sudan-IIIG (85869) and p-aminoazobenzene (62533). Contact allergies among machine tool workers have been reported for emulsifiable and nonemulsifiable oils, the latter including compound oils, inactive nonstaining oils and active staining oils. Sensitization has been attributed to the oil additives. Cutting oil dermatitis in machine tool workers, which was described as usually irritant but rarely allergic, was discussed. The existence of hexavalent-chromium in smoke from welding operations was considered as a cause of dermatitis in welders. Different plastics used in the bonding of metals such as polyurethanes, epoxy resins and phenoplast resins were considered, as well as the Aerodux, Hidux and Redux processes which utilize phenoplast resins. The involvement of chromium (7440473) in allergic eczema from galvanized sheet metal was described.","Metallurgy Abs: Job related contact allergies were reviewed in metallurgy workers including smelters, machine tool workers, welders, metal bonders and galvanized sheet metal warehousemen. The primary allergens affecting smelters were considered: hexavalent-chromium (18540299), phenoplastic resins and other allergens such as Sudan-IIIG (85869) and p-aminoazobenzene (62533). Contact allergies among machine tool workers have been reported for emulsifiable and nonemulsifiable oils, the latter including compound oils, inactive nonstaining oils and active staining oils. Sensitization has been attributed to the oil additives. Cutting oil dermatitis in machine tool workers, which was described as usually irritant but rarely allergic, was discussed. The existence of hexavalent-chromium in smoke from welding operations was considered as a cause of dermatitis in welders. Different plastics used in the bonding of metals such as polyurethanes, epoxy resins and phenoplast resins were considered, as well as the Aerodux, Hidux and Redux processes which utilize phenoplast resins. The involvement of chromium (7440473) in allergic eczema from galvanized sheet metal was described."
1514520,Forsberg et al. 1982,Development Of Protective Gloves. Work With Cutting Fluids In Metal Work. Material Study And New Test Method,"A protective glove for work with cutting fluids was developed and tested. The study included field investigations, material testing, and contact with producers. The protective effect of ten existing gloves was tested with regard to resistance against puncturing from a standardized penetration needle. Resistance to permeation by cutting fluids included measurement of both gas and fluid. Breakthrough time and rate of permeation were also determined. The penetration of chromium (18540299) and nickel (7440020) was observed by fluorescent X-ray analysis. A new test method used in the project partially measured the force necessary for the penetration needle to puncture a test material and the length of penetration. Seven cutting fluids were tested and represented emulsifiable cutting oil, straight cutting oil, and organic solvents. Resistance to permeation by emulsifiable oil and straight cutting oil was less than 3 hours for certain glove materials. Breakthrough time was less than 40 minutes for all glove materials studied. Chromium and nickel penetrated protective gloves when they were present in cutting fluids. Resistance to puncturing by the needle at a force of more than 25 newton units was demonstrated in gloves made of polyvinyl-chloride (9002862) with a textile base, both in a nitrile rubber glove and leather glove. Puncturing was not achieved for chloroprene (126998) or for natural rubber. Breakthrough limit was measured at about 6 newton units per square millimeter for nitrile rubber and about 12 newton units for chloroprene rubber. The break elongation was about 900 percent for nitrile rubber and 1200 percent for chloroprene rubber. The authors conclude that nitrile rubber appears to be the best prototype glove. (Swedish)","Development Of Protective Gloves. Work With Cutting Fluids In Metal Work. Material Study And New Test Method Abs: A protective glove for work with cutting fluids was developed and tested. The study included field investigations, material testing, and contact with producers. The protective effect of ten existing gloves was tested with regard to resistance against puncturing from a standardized penetration needle. Resistance to permeation by cutting fluids included measurement of both gas and fluid. Breakthrough time and rate of permeation were also determined. The penetration of chromium (18540299) and nickel (7440020) was observed by fluorescent X-ray analysis. A new test method used in the project partially measured the force necessary for the penetration needle to puncture a test material and the length of penetration. Seven cutting fluids were tested and represented emulsifiable cutting oil, straight cutting oil, and organic solvents. Resistance to permeation by emulsifiable oil and straight cutting oil was less than 3 hours for certain glove materials. Breakthrough time was less than 40 minutes for all glove materials studied. Chromium and nickel penetrated protective gloves when they were present in cutting fluids. Resistance to puncturing by the needle at a force of more than 25 newton units was demonstrated in gloves made of polyvinyl-chloride (9002862) with a textile base, both in a nitrile rubber glove and leather glove. Puncturing was not achieved for chloroprene (126998) or for natural rubber. Breakthrough limit was measured at about 6 newton units per square millimeter for nitrile rubber and about 12 newton units for chloroprene rubber. The break elongation was about 900 percent for nitrile rubber and 1200 percent for chloroprene rubber. The authors conclude that nitrile rubber appears to be the best prototype glove. (Swedish)"
1514519,Fornace 1981,Detection of DNA single strand breaks produced during the repair of damage by DNA-protein cross-linking agents,"HEEP COPYRIGHT: BIOL ABS. The combination of 1-beta-D-arabinofuranosylcytosine and hydroxyurea was used to inhibit the polymerase step of DNA excision repair. The DNA single-strand breaks (SSB), which accumulated in the presence of these agents, were measured by alkaline elution. DNA SSB were detected in normal human fibroblasts after exposure to trans-platinum(II)diamminedichloride, formaldehyde or potassium chromate. These agents all share the common feature that they induce DNA-protein cross-links in mammalian cells. In the case of trans-platinum(II)diamminedichloride or formaldehyde, the frequency of these SSB was markedly less in excision-deficient xeroderma pigmentosum cells. With chromate, a high level of SSB was induced in both normal (human) and xeroderma pigmentosum (human) cells; these results indicate that chromate damage to DNA is repaired by a mechanism different than the classical excision pathway since xeroderma pigmentosum cells responded normally. Several other agents were investigated with this approach and no SSB were detected with nickel sulfate, 12-O-tetradecanoylphorbol-13-acetate or asbestos fibers in the presence or absence of the polymerase inhibitor. This approach was a very sensitive method to detect DNA excision repair.","Detection of DNA single strand breaks produced during the repair of damage by DNA-protein cross-linking agents Abs: HEEP COPYRIGHT: BIOL ABS. The combination of 1-beta-D-arabinofuranosylcytosine and hydroxyurea was used to inhibit the polymerase step of DNA excision repair. The DNA single-strand breaks (SSB), which accumulated in the presence of these agents, were measured by alkaline elution. DNA SSB were detected in normal human fibroblasts after exposure to trans-platinum(II)diamminedichloride, formaldehyde or potassium chromate. These agents all share the common feature that they induce DNA-protein cross-links in mammalian cells. In the case of trans-platinum(II)diamminedichloride or formaldehyde, the frequency of these SSB was markedly less in excision-deficient xeroderma pigmentosum cells. With chromate, a high level of SSB was induced in both normal (human) and xeroderma pigmentosum (human) cells; these results indicate that chromate damage to DNA is repaired by a mechanism different than the classical excision pathway since xeroderma pigmentosum cells responded normally. Several other agents were investigated with this approach and no SSB were detected with nickel sulfate, 12-O-tetradecanoylphorbol-13-acetate or asbestos fibers in the presence or absence of the polymerase inhibitor. This approach was a very sensitive method to detect DNA excision repair."
1514513,Font et al. 1998,Physico-chemical characterzation and leaching of tannery wastes,"BIOSIS COPYRIGHT: BIOL ABS. The toxicity of tannery wastes was examined and discussed using several analytical methods and tests: X-ray fluorescence (XRF), Scanning electron microscopy X-ray spectrometer dispersive energy microanalysis (SEM-EDX); gas chromatography + mass spectrometry (GC-MS); acid nitric digestion; EP toxicity test; inductively coupled plasma atomic emission spectrometry (ICP-AES); biotoxicity tests with Photobacterium phosphoreum, Daphnia magna and Sprague-Dawley (rats); and other conventional tests. A comparison between the elements detected by X-ray fluorescence, scanning electron microscopy + X-ray spectrometer dispersive energy microanalysis and inductively coupled plasma atomic emission spectrometry after nitric acid digestion was carried out. A valoration of toxicity, considering the elements and compounds detected and the biotoxicity tests was done for each type of waste. Twenty-four samples of semi-processed leather trimmings and shavings, crust or finished chrome-tanned","Physico-chemical characterzation and leaching of tannery wastes Abs: BIOSIS COPYRIGHT: BIOL ABS. The toxicity of tannery wastes was examined and discussed using several analytical methods and tests: X-ray fluorescence (XRF), Scanning electron microscopy X-ray spectrometer dispersive energy microanalysis (SEM-EDX); gas chromatography + mass spectrometry (GC-MS); acid nitric digestion; EP toxicity test; inductively coupled plasma atomic emission spectrometry (ICP-AES); biotoxicity tests with Photobacterium phosphoreum, Daphnia magna and Sprague-Dawley (rats); and other conventional tests. A comparison between the elements detected by X-ray fluorescence, scanning electron microscopy + X-ray spectrometer dispersive energy microanalysis and inductively coupled plasma atomic emission spectrometry after nitric acid digestion was carried out. A valoration of toxicity, considering the elements and compounds detected and the biotoxicity tests was done for each type of waste. Twenty-four samples of semi-processed leather trimmings and shavings, crust or finished chrome-tanned"
1514512,Fodor and  Fischer 1995,Problems of the speciation of chromium in soil samples,Biosis copyright: biol abs. rrm research article chromiumiii chromiumvi pollution ion exchange chromatography organic extraction spectrophotometry analytical method,Problems of the speciation of chromium in soil samples Abs: Biosis copyright: biol abs. rrm research article chromiumiii chromiumvi pollution ion exchange chromatography organic extraction spectrophotometry analytical method
1514509,Fleeger and  Deng 1970,"Health Hazard Evaluation Report No. HETA-88-266-1970, Glennwood Range, Delaware, Ohio","In response to a request from at Glennwood Range (SIC-3469), Delaware, Ohio, a study was made of possible hazardous working conditions. At this facility 750 employees manufactured consumer gas and electric ranges. Several employees were suffering from skin disorders. Eighty seven of the employees worked in the Enamel Department where the primary responsibility was painting the individual range parts prior to their final construction. Porcelain enamel paints were applied to range parts by either a dipping or flow coat process. The porcelain enamels contained chromium (7440473) in the trivalent state. Oxidizers were added to the enamels, causing the potential for the trivalent chromium to change to a hexavalent state. The skin problems were found mainly among the ground coat line workers who were responsible for hanging parts on hooks to enter a curing oven. Most workers did not wear protective rubber gloves. It was determined that holes had developed in the heating coils of the curing oven, producing open flames. The open flames had caused burn off on the parts, and sharp edges developed on hooks used to hang parts. Samples taken from the hooks used to hang the range parts showed chromium(VI) concentrations of 0.09 to 2.41 micrograms per milligram of sample. Chromium(VI) concentrations in matter scraped from the hooks ranged from 0.3 to 4.4 micrograms/milligram. Sharp edges on the hooks caused abrasions on the hands of the worker, allowing the chromium a direct route of entry beneath the skin surface, causing the ulcerations. The authors conclude that a health hazard existed from exposure to chromium. The authors recommend measures for oven maintenance and worker protection.","Health Hazard Evaluation Report No. HETA-88-266-1970, Glennwood Range, Delaware, Ohio Abs: In response to a request from at Glennwood Range (SIC-3469), Delaware, Ohio, a study was made of possible hazardous working conditions. At this facility 750 employees manufactured consumer gas and electric ranges. Several employees were suffering from skin disorders. Eighty seven of the employees worked in the Enamel Department where the primary responsibility was painting the individual range parts prior to their final construction. Porcelain enamel paints were applied to range parts by either a dipping or flow coat process. The porcelain enamels contained chromium (7440473) in the trivalent state. Oxidizers were added to the enamels, causing the potential for the trivalent chromium to change to a hexavalent state. The skin problems were found mainly among the ground coat line workers who were responsible for hanging parts on hooks to enter a curing oven. Most workers did not wear protective rubber gloves. It was determined that holes had developed in the heating coils of the curing oven, producing open flames. The open flames had caused burn off on the parts, and sharp edges developed on hooks used to hang parts. Samples taken from the hooks used to hang the range parts showed chromium(VI) concentrations of 0.09 to 2.41 micrograms per milligram of sample. Chromium(VI) concentrations in matter scraped from the hooks ranged from 0.3 to 4.4 micrograms/milligram. Sharp edges on the hooks caused abrasions on the hands of the worker, allowing the chromium a direct route of entry beneath the skin surface, causing the ulcerations. The authors conclude that a health hazard existed from exposure to chromium. The authors recommend measures for oven maintenance and worker protection."
1514507,Ferri et al. 1996,Use of a modified chelating resin to study trace metals in environmental aqueous matrices,"BIOSIS COPYRIGHT: BIOL ABS. The paper describes the use of a commercially available chelating resin (Chelex-100) in Iron(III) form for the preconcentration of metals like Se, Te, Cr, and V from aqueous environmental matrices. The preconcentration procedure is very easy to perform: uptake of analytes occurs in batch (solution is treated with 0.5 g of resin under stirring for 10 min) after which the recovery (by NaOH) differs according to the analyte under test. The method is suitable for environmental concentration levels and practically free from interferences. In this paper, particularly, the preconcentration of Cr(VI) and V(IV,V) is described and compared with that of Se and Te defined previously. Finally we propose a method to study Cr speciation in aqueous systems; the method has been tested on actual samples.","Use of a modified chelating resin to study trace metals in environmental aqueous matrices Abs: BIOSIS COPYRIGHT: BIOL ABS. The paper describes the use of a commercially available chelating resin (Chelex-100) in Iron(III) form for the preconcentration of metals like Se, Te, Cr, and V from aqueous environmental matrices. The preconcentration procedure is very easy to perform: uptake of analytes occurs in batch (solution is treated with 0.5 g of resin under stirring for 10 min) after which the recovery (by NaOH) differs according to the analyte under test. The method is suitable for environmental concentration levels and practically free from interferences. In this paper, particularly, the preconcentration of Cr(VI) and V(IV,V) is described and compared with that of Se and Te defined previously. Finally we propose a method to study Cr speciation in aqueous systems; the method has been tested on actual samples."
1514506,Ferreira 1997,Use of Pimephales pomelas in toxicity evaluation of liquid effluents from the south petrochemical complex,"BIOSIS COPYRIGHT: BIOL ABS. The Integrated System for Treatment of Liquid Effluents (SITEL) is responsible for the treatment and discharge of liquid effluents produced at the South Petrochemical Complex (Brazil). Toxicity tests with Pimephales promelas were conducted along the treatment system in question to further study the toxic properties of its effluents. Lethal effects were assessed by Dunnett's test, and sublethal ones via histopathological analyses. Some toxicity was observed in the standard chronic larval test (7-day) and was found to be negligible. However, even showing no mortalities, histopathological alterations to the gills, such as epithelial separation, hyperplasia and increased mucus secretion were noticed during prolonged exposure to the final effluent on days 21 and 30. Physical and chemical analyses of effluent reveal some possible causes of that toxicity, including pH, concentrations of non-ionized ammonia and zinc and hardness. Since the maximum. values of the standard establ","Use of Pimephales pomelas in toxicity evaluation of liquid effluents from the south petrochemical complex Abs: BIOSIS COPYRIGHT: BIOL ABS. The Integrated System for Treatment of Liquid Effluents (SITEL) is responsible for the treatment and discharge of liquid effluents produced at the South Petrochemical Complex (Brazil). Toxicity tests with Pimephales promelas were conducted along the treatment system in question to further study the toxic properties of its effluents. Lethal effects were assessed by Dunnett's test, and sublethal ones via histopathological analyses. Some toxicity was observed in the standard chronic larval test (7-day) and was found to be negligible. However, even showing no mortalities, histopathological alterations to the gills, such as epithelial separation, hyperplasia and increased mucus secretion were noticed during prolonged exposure to the final effluent on days 21 and 30. Physical and chemical analyses of effluent reveal some possible causes of that toxicity, including pH, concentrations of non-ionized ammonia and zinc and hardness. Since the maximum. values of the standard establ"
1514501,Fendorf and  Zasoski 1992,Chromium(III) oxidation by delta-manganese oxide: 1. Characterization,"BIOSIS COPYRIGHT: BIOL ABS. The oxidation of Cr(III) by a common naturally occurring form of manganese oxide, delta-MnO2, was characterized over a range of Cr(III) concentrations and pH values. Cr(III) oxidation was limited as pH and Cr(III) concentrations increased. Reaction products, Mn(II) and Cr(VI), did not limit Cr(III) oxidation. Initial Cr(III) oxidation rates were very rapid at pH = 5, but were subsequently followed by a dramatic rate decline. Thermodynamic calculations using solution species indicated the reactio Cr(III) at pH > 3.5 appears to prohibit the extent of oxidation. Various mechanisms may account for the electrophoretic mobility and oxidation reactions; however, surface precipitation of chromium hydroxide seems to be the most plausible explanation based on our results. Chromium oxidation was dependent on Cr(III) concentration, pH, initial surface area, and ionic strength.","Chromium(III) oxidation by delta-manganese oxide: 1. Characterization Abs: BIOSIS COPYRIGHT: BIOL ABS. The oxidation of Cr(III) by a common naturally occurring form of manganese oxide, delta-MnO2, was characterized over a range of Cr(III) concentrations and pH values. Cr(III) oxidation was limited as pH and Cr(III) concentrations increased. Reaction products, Mn(II) and Cr(VI), did not limit Cr(III) oxidation. Initial Cr(III) oxidation rates were very rapid at pH = 5, but were subsequently followed by a dramatic rate decline. Thermodynamic calculations using solution species indicated the reactio Cr(III) at pH > 3.5 appears to prohibit the extent of oxidation. Various mechanisms may account for the electrophoretic mobility and oxidation reactions; however, surface precipitation of chromium hydroxide seems to be the most plausible explanation based on our results. Chromium oxidation was dependent on Cr(III) concentration, pH, initial surface area, and ionic strength."
1514500,Fehling et al. 1993,Field Validation for Sampling and Analysis of Airborne Hexavalent Chromium AU - Finley B,"A study of airborne hexavalent-chromium (18540299) (Cr+6) concentrations at industrial and residential sites using an impinger sampling train was conducted. A field validation of the impinger sampling method was also performed. Indoor and outdoor air particulate samples were collected at 25 industrial sites in Hudson County, New Jersey known to be contaminated with chromite ore residues using a three impinger sampling train. The soils at these sites at been previously analyzed and found to contain 13 to 210 parts per million (ppm) Cr+6 and 140 to 100,000ppm total chromium (7440473). Indoor samples were also collected at 15 residential sites in Hudson County distant from any known sources of chromite ore processing residues. Samples were analyzed for total chromium and Cr+6 by inductively coupled plasma mass spectrometry. Mean Cr+6 and total chromium concentrations in the indoor air samples obtained at the industrial sites ranged from 0.23 to 5.1 and 5.0 to 130 nanograms/cubic meter (ng/m3), respectively. Mean Cr+6 and total chromium concentrations in outdoor air samples from the industrial sites varied from 0.13 to 15.3 and 1.9 to 84.5ng/m3, respectively. Indoor air Cr+6 and total chromium concentrations measured at the residential sites ranged from 0.38 to 3.3 and 3.8 to 12ng/m3, respectively. Twenty eight of 44 Cr+6 concentrations measured in the indoor and outdoor air samples at the industrial sites fell within the range of the Cr+6 concentrations measured at the residential sites. Twenty four triple impinger sampling trains were placed at six sites at a former chromite ore processing site at Kearny, New Jersey. The data were compared with data obtained by co-located double impinger sampling trains. The authors conclude that the triple impinger sampling train technique is suitable for measuring airborne Cr+6 concentrations. Elevated Cr+6 concentrations in soils do not necessarily result in elevated Cr+6 concentrations in the ambient air.","Field Validation for Sampling and Analysis of Airborne Hexavalent Chromium AU - Finley B Abs: A study of airborne hexavalent-chromium (18540299) (Cr+6) concentrations at industrial and residential sites using an impinger sampling train was conducted. A field validation of the impinger sampling method was also performed. Indoor and outdoor air particulate samples were collected at 25 industrial sites in Hudson County, New Jersey known to be contaminated with chromite ore residues using a three impinger sampling train. The soils at these sites at been previously analyzed and found to contain 13 to 210 parts per million (ppm) Cr+6 and 140 to 100,000ppm total chromium (7440473). Indoor samples were also collected at 15 residential sites in Hudson County distant from any known sources of chromite ore processing residues. Samples were analyzed for total chromium and Cr+6 by inductively coupled plasma mass spectrometry. Mean Cr+6 and total chromium concentrations in the indoor air samples obtained at the industrial sites ranged from 0.23 to 5.1 and 5.0 to 130 nanograms/cubic meter (ng/m3), respectively. Mean Cr+6 and total chromium concentrations in outdoor air samples from the industrial sites varied from 0.13 to 15.3 and 1.9 to 84.5ng/m3, respectively. Indoor air Cr+6 and total chromium concentrations measured at the residential sites ranged from 0.38 to 3.3 and 3.8 to 12ng/m3, respectively. Twenty eight of 44 Cr+6 concentrations measured in the indoor and outdoor air samples at the industrial sites fell within the range of the Cr+6 concentrations measured at the residential sites. Twenty four triple impinger sampling trains were placed at six sites at a former chromite ore processing site at Kearny, New Jersey. The data were compared with data obtained by co-located double impinger sampling trains. The authors conclude that the triple impinger sampling train technique is suitable for measuring airborne Cr+6 concentrations. Elevated Cr+6 concentrations in soils do not necessarily result in elevated Cr+6 concentrations in the ambient air."
1514498,Favali et al. 1990,The effect of chromium-vi on maize roots i. cyto-morphological study,Biosis copyright: biol abs. rrm abstract zea-mays light microscopy electron microscopy protein depletion,The effect of chromium-vi on maize roots i. cyto-morphological study Abs: Biosis copyright: biol abs. rrm abstract zea-mays light microscopy electron microscopy protein depletion
1514494,Falerios et al. 1992,Airborne concentrations of trivalent and hexavalent chromium from contaminated soils at unpaved and partially paved commercial/industrial sites,"BIOSIS COPYRIGHT: BIOL ABS. The primary health hazard to people in areas surrounding contaminated sites is often believed to be exposure to airborne contaminants. Due to insensitive sampling or analytical methods for many chemicals, including hexavalent chromium (Cr(VI)), the only option available for quantifying the hazard posed by ambient airborne concentrations of these chemicals has been limited to predictions based on various modeling approaches. Due to the use of compounded worst-case input parameters in the models, the resulting predictions have often been of questionable accuracy and relevancy. A recent advance in the sampling and analytical method for airborne Cr(VI) has enabled direct measurement of the low concentrations typically found in ambient air. This method was used to quantify airborne Cr(VI) levels at both indoor and outdoor locations at 21 sites in Hudson County, New Jersey (USA) which have soils containing chromite ore processing residue. Of the 21 sites evaluated, nine were","Airborne concentrations of trivalent and hexavalent chromium from contaminated soils at unpaved and partially paved commercial/industrial sites Abs: BIOSIS COPYRIGHT: BIOL ABS. The primary health hazard to people in areas surrounding contaminated sites is often believed to be exposure to airborne contaminants. Due to insensitive sampling or analytical methods for many chemicals, including hexavalent chromium (Cr(VI)), the only option available for quantifying the hazard posed by ambient airborne concentrations of these chemicals has been limited to predictions based on various modeling approaches. Due to the use of compounded worst-case input parameters in the models, the resulting predictions have often been of questionable accuracy and relevancy. A recent advance in the sampling and analytical method for airborne Cr(VI) has enabled direct measurement of the low concentrations typically found in ambient air. This method was used to quantify airborne Cr(VI) levels at both indoor and outdoor locations at 21 sites in Hudson County, New Jersey (USA) which have soils containing chromite ore processing residue. Of the 21 sites evaluated, nine were"
1514491,Eur 1980,Water quality criteria for European freshwater fish: Combined effects on freshwater fish and other aquatic life of mixtures of toxicants in water,"HEEP COPYRIGHT: BIOL ABS. Examination of available data using the concentration-addition model showed that for mixtures of toxicants found in sewage and industrial effluents, the joint acutely lethal (LC50) toxicity to fish (including rainbow trout) and other aquatic organisms was close to that predicted, assuming addition of the proportional contribution from each toxicant. This model was adequate to describe the joint effect of commoly occurring constituents of sewage and industrial waste.","Water quality criteria for European freshwater fish: Combined effects on freshwater fish and other aquatic life of mixtures of toxicants in water Abs: HEEP COPYRIGHT: BIOL ABS. Examination of available data using the concentration-addition model showed that for mixtures of toxicants found in sewage and industrial effluents, the joint acutely lethal (LC50) toxicity to fish (including rainbow trout) and other aquatic organisms was close to that predicted, assuming addition of the proportional contribution from each toxicant. This model was adequate to describe the joint effect of commoly occurring constituents of sewage and industrial waste."
1514490,Eun et al. 1986,An epidemiological study of contact dermatitis,Biosis copyright: biol abs. rrm human leg ulcer housewife hand eczema ammoniated mercury nickel sulfate potassium dichromate cinnamic alcohol neomycin sulfate paraphenylenediammine thimerosal patch test korean contact dermatitis research group,An epidemiological study of contact dermatitis Abs: Biosis copyright: biol abs. rrm human leg ulcer housewife hand eczema ammoniated mercury nickel sulfate potassium dichromate cinnamic alcohol neomycin sulfate paraphenylenediammine thimerosal patch test korean contact dermatitis research group
1514486,Elwood et al. 1980,Chromium levels in fish from a lake chronically contaminated with chromates from cooling towers,"HEEP COPYRIGHT: BIOL ABS. Cr concentrations of several fish species (bluegill (Lepomis macrochirus), largemouth bass (Micropterus salmoides) goldfish (Carassius auratus), and mosquitofish (Gambusia affinis)) from White Oak Lake (WOL) (eastern Tennessee, USA), a small impoundment which formerly received cooling water blowdown containing high Cr(VI) concentrations, were measured to determine levels of tissue accumulation. Cr concentrations in the muscle and/or whole body (excluding gastrointestinal tract) of some species in some years were negatively correlated with total fish weight. Results suggest that Cr levels in muscle and whole body of most species analyzed from WOL and from Melton Hill Reservoir, an uncontaminated impoundment, may be inversely related to fish weight. Muscle and wholebody Cr concentrations were not significantly different from each other in bluegill or largemouth bass. With the exception of goldfish collected in 1969, between species comparisons of Cr levels in WOL fish within years showed no statistically significant differences, indicating that there was no trophic level effect on Cr accumulation in tissues of the species examined. There was also no significant difference in Cr concentration in muscle of bluegill and largemouth bass from WOL and Melton Hill Reservoir, indicating that these species either effectively regulate their Cr absorption or that the elevated Cr levels in WOL were in a form that is unavailable for absorption into tissues.","Chromium levels in fish from a lake chronically contaminated with chromates from cooling towers Abs: HEEP COPYRIGHT: BIOL ABS. Cr concentrations of several fish species (bluegill (Lepomis macrochirus), largemouth bass (Micropterus salmoides) goldfish (Carassius auratus), and mosquitofish (Gambusia affinis)) from White Oak Lake (WOL) (eastern Tennessee, USA), a small impoundment which formerly received cooling water blowdown containing high Cr(VI) concentrations, were measured to determine levels of tissue accumulation. Cr concentrations in the muscle and/or whole body (excluding gastrointestinal tract) of some species in some years were negatively correlated with total fish weight. Results suggest that Cr levels in muscle and whole body of most species analyzed from WOL and from Melton Hill Reservoir, an uncontaminated impoundment, may be inversely related to fish weight. Muscle and wholebody Cr concentrations were not significantly different from each other in bluegill or largemouth bass. With the exception of goldfish collected in 1969, between species comparisons of Cr levels in WOL fish within years showed no statistically significant differences, indicating that there was no trophic level effect on Cr accumulation in tissues of the species examined. There was also no significant difference in Cr concentration in muscle of bluegill and largemouth bass from WOL and Melton Hill Reservoir, indicating that these species either effectively regulate their Cr absorption or that the elevated Cr levels in WOL were in a form that is unavailable for absorption into tissues."
1514485,El-Wakil et al. 1993,Iodometric microgram determination of chromium(III) and (VI) by use of chemical amplification reactions,"BIOSIS COPYRIGHT: BIOL ABS. A simple, rapid and sensitive method is described for the iodometric determination of microgram amounts of chromium(III), based on the oxidation of chromium(III) with periodate at pH 3.2, removal of the unreacted periodate by masking with molybdate and subsequent iodometric determination of the liberated iodate. Chromium(VI) can be determined by this method after prior reduction to chromium(III) with sodium sulphite. The method can also be used for the analysis of organochromium compounds.","Iodometric microgram determination of chromium(III) and (VI) by use of chemical amplification reactions Abs: BIOSIS COPYRIGHT: BIOL ABS. A simple, rapid and sensitive method is described for the iodometric determination of microgram amounts of chromium(III), based on the oxidation of chromium(III) with periodate at pH 3.2, removal of the unreacted periodate by masking with molybdate and subsequent iodometric determination of the liberated iodate. Chromium(VI) can be determined by this method after prior reduction to chromium(III) with sodium sulphite. The method can also be used for the analysis of organochromium compounds."
1514484,El-Wakil et al. 1990,Trace analysis by direct spectrophotometric measurements on polyurethane foam: Determination of chromium(VI) as blue perchromic acid with unloaded and tri-n-butylphosphate loaded foam,"BIOSIS COPYRIGHT: BIOL ABS. The formation of blue perchromic acid represents one of the most sensitive and selective tests for the identification of chromium. The sorption of perchromic acid on TBP loaded foam has been investigated for the detection, semiquantitative and quantitative determinations of chromium (VI). In foam batch method, it was possible to detect as low as 0.6, 0.4 and 0.2 ppm of chromium (VI) with unloaded or tricaprylylamine loaded foams, TBP-amine-loaded foams and TBP loaded foams, respectively. The selectivity of the proposed TBP loaded foam test for the detection of chromium (VI) in the presence of diverse interfering ions was also investigated. In addition, it was possible to determine chromium (VI) semiquantitatively by comparing the colour of the foam cube with a prepared standard colour scale. The proposed method has been employed for the determination of chromium (VI) in tap water. A method for the direct and quantitative spectrophotometric determination of chromium (VI)","Trace analysis by direct spectrophotometric measurements on polyurethane foam: Determination of chromium(VI) as blue perchromic acid with unloaded and tri-n-butylphosphate loaded foam Abs: BIOSIS COPYRIGHT: BIOL ABS. The formation of blue perchromic acid represents one of the most sensitive and selective tests for the identification of chromium. The sorption of perchromic acid on TBP loaded foam has been investigated for the detection, semiquantitative and quantitative determinations of chromium (VI). In foam batch method, it was possible to detect as low as 0.6, 0.4 and 0.2 ppm of chromium (VI) with unloaded or tricaprylylamine loaded foams, TBP-amine-loaded foams and TBP loaded foams, respectively. The selectivity of the proposed TBP loaded foam test for the detection of chromium (VI) in the presence of diverse interfering ions was also investigated. In addition, it was possible to determine chromium (VI) semiquantitatively by comparing the colour of the foam cube with a prepared standard colour scale. The proposed method has been employed for the determination of chromium (VI) in tap water. A method for the direct and quantitative spectrophotometric determination of chromium (VI)"
1514482,Elleouet et al. 1992,Determination of trace amounts of chromium(VI) in water by electrochemical methods,"BIOSIS COPYRIGHT: BIOL ABS. A sensitive procedure for the determination of chromium(VI) is described. A chelate of chromium with an organic ligand is adsorbed on a hanging mercury drop electrode and the reduction current of the accumulated chelate is measured by differential-pulse voltammetry. The effects of various parameters (pH, ligand concentration, potential and collection time) on the response are discussed. Possible interferences by trace metals and organic matter are considered.","Determination of trace amounts of chromium(VI) in water by electrochemical methods Abs: BIOSIS COPYRIGHT: BIOL ABS. A sensitive procedure for the determination of chromium(VI) is described. A chelate of chromium with an organic ligand is adsorbed on a hanging mercury drop electrode and the reduction current of the accumulated chelate is measured by differential-pulse voltammetry. The effects of various parameters (pH, ligand concentration, potential and collection time) on the response are discussed. Possible interferences by trace metals and organic matter are considered."
1514477,Eleiwa and  Naguib 1987,Effect of chromium on the carbohydrate of datura-stramonium leaves,Biosis copyright: biol abs. rrm glycoproteins pentosan hexosans sugars sucrose,Effect of chromium on the carbohydrate of datura-stramonium leaves Abs: Biosis copyright: biol abs. rrm glycoproteins pentosan hexosans sugars sucrose
1514476,El Khorassani et al. 1999,A simple UV spectrophotometric procedure for the survey of industrial sewage system,"BIOSIS COPYRIGHT: BIOL ABS. A simple UV spectrophotometric procedure is proposed for the survey of an industrial sewage system. Simple, fast and reliable, this technique has been first designed for natural and waste water. It is based on the assumption that any UV spectrum of a sample can be decomposed by using a set of reference spectra. The main application is the determination of specific compounds such as nitrate or anionic surfactants (expressed as DBS) or the estimation of global parameters such as COD, TOC or TSS. Another interest can be found in process control or alarm detection. Based on the UV light absorption by all unsaturated compounds and particularly anthropogenic organic matter, the method is obviously limited by the nature of organics. So, its use for industrial application needs a good knowledge of wastewater composition -and variation- for the choice of the dedicated spectra library. This paper will present the industrial application of UV spectrophotometry including the methods for the definition of the spectra libraries. Its application in the wastewater survey of a large petrochemical site, located in the South of France, is also presented.","A simple UV spectrophotometric procedure for the survey of industrial sewage system Abs: BIOSIS COPYRIGHT: BIOL ABS. A simple UV spectrophotometric procedure is proposed for the survey of an industrial sewage system. Simple, fast and reliable, this technique has been first designed for natural and waste water. It is based on the assumption that any UV spectrum of a sample can be decomposed by using a set of reference spectra. The main application is the determination of specific compounds such as nitrate or anionic surfactants (expressed as DBS) or the estimation of global parameters such as COD, TOC or TSS. Another interest can be found in process control or alarm detection. Based on the UV light absorption by all unsaturated compounds and particularly anthropogenic organic matter, the method is obviously limited by the nature of organics. So, its use for industrial application needs a good knowledge of wastewater composition -and variation- for the choice of the dedicated spectra library. This paper will present the industrial application of UV spectrophotometry including the methods for the definition of the spectra libraries. Its application in the wastewater survey of a large petrochemical site, located in the South of France, is also presented."
1514474,Ehman et al. 1986,The determination of low levels of airborne total chromium and chromium-vi by atomic absorption and inductively-coupled plasma emission spectroscopy,Biosis copyright: biol abs. rrm abstract air pollution metal pollution,The determination of low levels of airborne total chromium and chromium-vi by atomic absorption and inductively-coupled plasma emission spectroscopy Abs: Biosis copyright: biol abs. rrm abstract air pollution metal pollution
1514472,Edgell et al. 1994,"Ion chromatographic method for dissolved hexavalent chromium in drinking water, groundwater, and industrial wastewater effluents: Collaborative study","BIOSIS COPYRIGHT: BIOL ABS. A collaborative study was conducted by the U.S. Environmental Protection Agency (U.S. EPA) and the American Society for Testing Materials (ASTM) on an ion chromatographic method for the determination of hexavalent chromium (U.S. EPA method 218.6, and the ASTM equivalent method). This study was designed to determine the mean recovery and precision of analyses for hexavalent chromium in reagent water, drinking water, groundwater, and industrial wastewaters. The study design was based on Youden's nonreplicate plan for collaborative studies of analytical methods. The test waters were spiked with hexavalent chromium at 8 concentration levels, prepared as 4 Youden pairs. A fifth Youden concentration pair was also included to determine method performance close to the method detection limit. Twenty-one laboratories were instructed to filter their test waters through a 0.45 mum filter and to adjust the pH of the filtrate to 9-9.5 with an ammonium sulfate/ammonium hydroxide buffe","Ion chromatographic method for dissolved hexavalent chromium in drinking water, groundwater, and industrial wastewater effluents: Collaborative study Abs: BIOSIS COPYRIGHT: BIOL ABS. A collaborative study was conducted by the U.S. Environmental Protection Agency (U.S. EPA) and the American Society for Testing Materials (ASTM) on an ion chromatographic method for the determination of hexavalent chromium (U.S. EPA method 218.6, and the ASTM equivalent method). This study was designed to determine the mean recovery and precision of analyses for hexavalent chromium in reagent water, drinking water, groundwater, and industrial wastewaters. The study design was based on Youden's nonreplicate plan for collaborative studies of analytical methods. The test waters were spiked with hexavalent chromium at 8 concentration levels, prepared as 4 Youden pairs. A fifth Youden concentration pair was also included to determine method performance close to the method detection limit. Twenty-one laboratories were instructed to filter their test waters through a 0.45 mum filter and to adjust the pH of the filtrate to 9-9.5 with an ammonium sulfate/ammonium hydroxide buffe"
1514471,Eckert et al. 1991,Response of chromium(V) to the diphenylcarbazide spectrophotometric method for the determination of chromium(VI),"BIOSIS COPYRIGHT: BIOL ABS. Two chromium(V) complexes are shown to respond to the diphenylcarbazide spectrophotometric method for the determination of chromium(VI), but with only 60% of the efficiency of Cr(VI). Acidification to pH 1-2 in the presence of dissolved organic matter results in substantial reduction of the Cr(V) within 24 h.","Response of chromium(V) to the diphenylcarbazide spectrophotometric method for the determination of chromium(VI) Abs: BIOSIS COPYRIGHT: BIOL ABS. Two chromium(V) complexes are shown to respond to the diphenylcarbazide spectrophotometric method for the determination of chromium(VI), but with only 60% of the efficiency of Cr(VI). Acidification to pH 1-2 in the presence of dissolved organic matter results in substantial reduction of the Cr(V) within 24 h."
1514469,Echt et al. ,"Health Hazard Evaluation Report No. HETA-94-0417-2505, Tennant Company, Minneapolis, Minnesota","In response to a request from employees at the Golden Valley facility of the Tennant Company (SIC-3589), Minneapolis, Minnesota, a health hazard evaluation was conducted. Concern had been expressed over indoor environmental quality in offices and exposure to welding fumes. The company manufactured floor sweepers, scrubbers, and scarifiers. Headaches, sneezing, burning eyes, fatigue, depression, and mood swings were reported among office workers. Overall, 58% of those surveyed had one or more symptoms that occurred at work one or more days a week. Exposures to welding fume and most metals were below the applicable evaluation criteria. Eight hour time weighted average welding fume concentrations ranged from 0.33 to 1.6mg/m3. Titanium-dioxide (13463677) was present in greater than trace amounts in two of five samples; NIOSH has recommended that titanium-dioxide exposures be reduced to the lowest feasible concentration. Total chromium (7440473) exposure ranged from 0.003 to 0.01mg/m3, indicating that potential exposures to hexavalent chromium among frame welders should be evaluated. Manganese exposures ranged from 0.083 to 0.27mg/m3. The authors conclude that exposures to titanium-dioxide, chromium, and manganese were a cause for concern. Although no apparent cause for symptoms in office workers was found, ventilation system deficiencies were present. The authors recommend specific measures to reduce exposures and improve working conditions.","Health Hazard Evaluation Report No. HETA-94-0417-2505, Tennant Company, Minneapolis, Minnesota Abs: In response to a request from employees at the Golden Valley facility of the Tennant Company (SIC-3589), Minneapolis, Minnesota, a health hazard evaluation was conducted. Concern had been expressed over indoor environmental quality in offices and exposure to welding fumes. The company manufactured floor sweepers, scrubbers, and scarifiers. Headaches, sneezing, burning eyes, fatigue, depression, and mood swings were reported among office workers. Overall, 58% of those surveyed had one or more symptoms that occurred at work one or more days a week. Exposures to welding fume and most metals were below the applicable evaluation criteria. Eight hour time weighted average welding fume concentrations ranged from 0.33 to 1.6mg/m3. Titanium-dioxide (13463677) was present in greater than trace amounts in two of five samples; NIOSH has recommended that titanium-dioxide exposures be reduced to the lowest feasible concentration. Total chromium (7440473) exposure ranged from 0.003 to 0.01mg/m3, indicating that potential exposures to hexavalent chromium among frame welders should be evaluated. Manganese exposures ranged from 0.083 to 0.27mg/m3. The authors conclude that exposures to titanium-dioxide, chromium, and manganese were a cause for concern. Although no apparent cause for symptoms in office workers was found, ventilation system deficiencies were present. The authors recommend specific measures to reduce exposures and improve working conditions."
1514468,Echeverria et al. 1999,Metal-induced chromium(VI) sorption by two calcareous soils,"BIOSIS COPYRIGHT: BIOL ABS. Competing anions, notably SO42- and H2PO4-, reduce Cr(VI) sorption; however, the role of cooperative cations in Cr(VI) retention has merited less attention. This research studied the effect of Cd, Cu, Ni, and Zn on sorption of Cr(VI) in 2 calcareous soils: Calcixerollic Xerochrept (CX) and Paralithic Xerorthent (PX). Sorption kinetics and isotherms were combined with sequential extractions and fractional factorial designs. Most cation sorption took place during the first hour, whereas sorption o 07 mM for the CX soil and 0.17 mM for the PX soil. For higher concentrations, sorption of Cr(VI) by both soils was described by a constant distribution isotherm. More than 80% of Cr(VI) sorbed by soils was extracted as a non-exchangeable fraction using the Tessier et al. sequential procedure. Fractional factorial designs indicated that although the 4 cations favoured sorption of Cr(VI), Cu had the greatest positive influence.","Metal-induced chromium(VI) sorption by two calcareous soils Abs: BIOSIS COPYRIGHT: BIOL ABS. Competing anions, notably SO42- and H2PO4-, reduce Cr(VI) sorption; however, the role of cooperative cations in Cr(VI) retention has merited less attention. This research studied the effect of Cd, Cu, Ni, and Zn on sorption of Cr(VI) in 2 calcareous soils: Calcixerollic Xerochrept (CX) and Paralithic Xerorthent (PX). Sorption kinetics and isotherms were combined with sequential extractions and fractional factorial designs. Most cation sorption took place during the first hour, whereas sorption o 07 mM for the CX soil and 0.17 mM for the PX soil. For higher concentrations, sorption of Cr(VI) by both soils was described by a constant distribution isotherm. More than 80% of Cr(VI) sorbed by soils was extracted as a non-exchangeable fraction using the Tessier et al. sequential procedure. Fractional factorial designs indicated that although the 4 cations favoured sorption of Cr(VI), Cu had the greatest positive influence."
1514467,Eary and  Rai 1987,Kinetics of chromium-iii oxidation to chromium-vi by reaction with manganese dioxide,Biosis copyright: biol abs. rrm pyrolusite chromium transport industrial waste material groundwater contamination water pollution,Kinetics of chromium-iii oxidation to chromium-vi by reaction with manganese dioxide Abs: Biosis copyright: biol abs. rrm pyrolusite chromium transport industrial waste material groundwater contamination water pollution
1514465,Dyg et al. 1994,Development and interlaboratory testing of aqueous and lyophilized criii and crvi reference materials,Biosis copyright: biol abs. rrm research article human chromiumiii chromiumvi stability occupational health speciation technique analytical method,Development and interlaboratory testing of aqueous and lyophilized criii and crvi reference materials Abs: Biosis copyright: biol abs. rrm research article human chromiumiii chromiumvi stability occupational health speciation technique analytical method
1514464,Dyg et al. 1994,Preparation of Filters Loaded with Welding Dust. A Homogeneity and Stability Study of Hexavalent Chromium,"A technique for producing air filters loaded with a homogenous, stable distribution of hexavalent chromium (7440473) (Cr+6) was described. The filters were to be used as control materials in an international laboratory study directed at validating state of the art technology for chromium speciation and to assess the suitability of the filters as candidate certified reference materials. Welding fume samples originating from a computerized manual metal arc welding process were collected on 100 binder free borosilicate glass fiber filters that were placed in the rings of an air sampling unit at a homogeneous flow rate of 2 liters per minute. This produced welding fume concentrations on the filters that averaged 2.565 milligrams per filter with a relative coefficient of variation (RCV) of 3.4%. Analyses of welding fumes collected on 16 filters randomly selected from the four rings of the air sampler utilizing electrothermal atomic emission spectrometry found an average Cr+6 concentration of 115.9 micrograms per filter (microg/filter) and an average total chromium concentration of 112.8microg/filter. The RCVs for these analyses were only 1.9 and 4.4%, respectively. No trivalent chromium (Cr+3) was detected. Analysis of loaded filters that had been stored at 25 and -20 degrees-C for 1, 4, and 13 weeks indicated no loss of chromium or Cr+6 and no detectable Cr+3. The authors conclude that this technique can produce a batch of filters with a homogeneous distribution of stable Cr+6.","Preparation of Filters Loaded with Welding Dust. A Homogeneity and Stability Study of Hexavalent Chromium Abs: A technique for producing air filters loaded with a homogenous, stable distribution of hexavalent chromium (7440473) (Cr+6) was described. The filters were to be used as control materials in an international laboratory study directed at validating state of the art technology for chromium speciation and to assess the suitability of the filters as candidate certified reference materials. Welding fume samples originating from a computerized manual metal arc welding process were collected on 100 binder free borosilicate glass fiber filters that were placed in the rings of an air sampling unit at a homogeneous flow rate of 2 liters per minute. This produced welding fume concentrations on the filters that averaged 2.565 milligrams per filter with a relative coefficient of variation (RCV) of 3.4%. Analyses of welding fumes collected on 16 filters randomly selected from the four rings of the air sampler utilizing electrothermal atomic emission spectrometry found an average Cr+6 concentration of 115.9 micrograms per filter (microg/filter) and an average total chromium concentration of 112.8microg/filter. The RCVs for these analyses were only 1.9 and 4.4%, respectively. No trivalent chromium (Cr+3) was detected. Analysis of loaded filters that had been stored at 25 and -20 degrees-C for 1, 4, and 13 weeks indicated no loss of chromium or Cr+6 and no detectable Cr+3. The authors conclude that this technique can produce a batch of filters with a homogeneous distribution of stable Cr+6."
1514463,Dutkiewicz et al. 1969,Assessment of the Colorimetric Methods of Determination of Chromium in Air and Urine by Means of Radioisotope Techniques,"An evaluation of the colorimetric methods of determination of chromium (7440473) in air and urine based on the reaction of hexavalent chromium with diphenylcarbazide is carried out, using radioisotope techniques as the comparative method. The recovery of chromium solid absorbers is not complete because of the reduction of hexavalent chromium to trivalent chromium. The procedure for determining chromium in urine provides for a constant recovery of 50 percent of chromium as compared with the determinations carried out in aqueous solutions. (Russian: English translation available)","Assessment of the Colorimetric Methods of Determination of Chromium in Air and Urine by Means of Radioisotope Techniques Abs: An evaluation of the colorimetric methods of determination of chromium (7440473) in air and urine based on the reaction of hexavalent chromium with diphenylcarbazide is carried out, using radioisotope techniques as the comparative method. The recovery of chromium solid absorbers is not complete because of the reduction of hexavalent chromium to trivalent chromium. The procedure for determining chromium in urine provides for a constant recovery of 50 percent of chromium as compared with the determinations carried out in aqueous solutions. (Russian: English translation available)"
1514462,Dunphy and  George 1983,Aircraft And Aerospace Industry,"Safety and health hazards and preventive measures in the aircraft and aerospace industry (SIC-3721) are reviewed. Safety hazards include tripping on irregular or littered work surfaces, falling from overhead crane catwalks, ladders, aero stands, and major assembly jigs, and touching ungrounded electrical equipment, sharp cutting tools, flying chips, and particles from drilling. Health hazards include exposure to extremes in temperature and noise, ionizing and non ionizing radiation, dust generated while machining beryllium (7440417 alloys, fumes generated by heating cadmium (7440439) and lead (7439921), exposure to hexavalent chromium (7440473) nitrogen oxides, phosgene (75445), and ozone (10028156) during welding processes, and developing contact dermatitis from cutting oils. Workers are frequently exposed to aromatic and halogenated hydrocarbons, synthetic resins, epoxy resins, diisocyanates, silicon-dioxide (7631869) in sand blasting, and fiberglass, each of which presents unique and dangerous occupational hazards. A number of safety and health measures that have been implemented by the industry are reviewed. The authors conclude that the integration of safety programs with research, design, engineering, and manufacturing activities has been effective in controlling all forms of occupational injury and illness.","Aircraft And Aerospace Industry Abs: Safety and health hazards and preventive measures in the aircraft and aerospace industry (SIC-3721) are reviewed. Safety hazards include tripping on irregular or littered work surfaces, falling from overhead crane catwalks, ladders, aero stands, and major assembly jigs, and touching ungrounded electrical equipment, sharp cutting tools, flying chips, and particles from drilling. Health hazards include exposure to extremes in temperature and noise, ionizing and non ionizing radiation, dust generated while machining beryllium (7440417 alloys, fumes generated by heating cadmium (7440439) and lead (7439921), exposure to hexavalent chromium (7440473) nitrogen oxides, phosgene (75445), and ozone (10028156) during welding processes, and developing contact dermatitis from cutting oils. Workers are frequently exposed to aromatic and halogenated hydrocarbons, synthetic resins, epoxy resins, diisocyanates, silicon-dioxide (7631869) in sand blasting, and fiberglass, each of which presents unique and dangerous occupational hazards. A number of safety and health measures that have been implemented by the industry are reviewed. The authors conclude that the integration of safety programs with research, design, engineering, and manufacturing activities has been effective in controlling all forms of occupational injury and illness."
1514458,Dua et al. 1993,"Effect of chromium on seed germination, seedling growth and yield of peas. AU - BISHNOI NR","BIOSIS COPYRIGHT: BIOL ABS. Hexavalent chromium (Cr6+) supplied as potassium dichromate did not affect percent germination of pea seeds, but at concentrations above 0.5 mM suppressed growth of radicle and plumule significantly. In contrast, Cr6+ was much more toxic when applied to 40 day old seedlings grown, either on combined nitrogen, or under nitrogen-fixing conditions. Its deleterious effect was more pronounced on the growth of roots than on shoots. Though Cr6+ hastened flowering, the total number of flowers and consequently the number of pods per plant was reduced drastically. In chromium-treated plants a larger proportion of pods failed to set seeds and the average number of seeds per pod was lower. All these factors contributed towards lowering seed yield of the plants receiving 0.2 mM Cr6+ by 75-80%. The impact of this metal on growth was more severe on plants supplied with combined nitrogen than on nitrogen-fixing plants. Concentration of the metal in various plant parts was: roots > l","Effect of chromium on seed germination, seedling growth and yield of peas. AU - BISHNOI NR Abs: BIOSIS COPYRIGHT: BIOL ABS. Hexavalent chromium (Cr6+) supplied as potassium dichromate did not affect percent germination of pea seeds, but at concentrations above 0.5 mM suppressed growth of radicle and plumule significantly. In contrast, Cr6+ was much more toxic when applied to 40 day old seedlings grown, either on combined nitrogen, or under nitrogen-fixing conditions. Its deleterious effect was more pronounced on the growth of roots than on shoots. Though Cr6+ hastened flowering, the total number of flowers and consequently the number of pods per plant was reduced drastically. In chromium-treated plants a larger proportion of pods failed to set seeds and the average number of seeds per pod was lower. All these factors contributed towards lowering seed yield of the plants receiving 0.2 mM Cr6+ by 75-80%. The impact of this metal on growth was more severe on plants supplied with combined nitrogen than on nitrogen-fixing plants. Concentration of the metal in various plant parts was: roots > l"
1514456,Driscoll and  Kaplan 1987,Assessment of alternative technologies for treating spent electroplating solutions and sludges,"HMTC Treatment of spent electroplating solutions and sludges by combined chemical/physical methods was evaluated for a facility with a total treatment capacity of 10 million gal per year. Liquids were treated by cyanide oxidation, hexavalent chromium reduction, metals precipitation with lime slurry, and vacuum filtration. Solid wastes were stabilized with calcium hypochlorite, ferric sulfate crystals, and/or lime. Metal removal efficiency was above 99.8% for chromium, copper, lead, and nickel but was 70.9% for one batch containing zinc. Hexavalent chromium and zinc levels exceeded discharge levels once during the sampling period. Overall, the system was considered successful for electroplating and metal finishing waste treatment.","Assessment of alternative technologies for treating spent electroplating solutions and sludges Abs: HMTC Treatment of spent electroplating solutions and sludges by combined chemical/physical methods was evaluated for a facility with a total treatment capacity of 10 million gal per year. Liquids were treated by cyanide oxidation, hexavalent chromium reduction, metals precipitation with lime slurry, and vacuum filtration. Solid wastes were stabilized with calcium hypochlorite, ferric sulfate crystals, and/or lime. Metal removal efficiency was above 99.8% for chromium, copper, lead, and nickel but was 70.9% for one batch containing zinc. Hexavalent chromium and zinc levels exceeded discharge levels once during the sampling period. Overall, the system was considered successful for electroplating and metal finishing waste treatment."
1514454,Doughtie and  Rao 1984,"Histopathological and ultrastructural changes in the antennal gland, midgut, hepatopancreas and gill of grass shrimp (Palaemonetes pugio) following exposure to hexavalent chromium","HEEP COPYRIGHT: BIOL ABS. Grass shrimp, P. pugio, were exposed for 1 mo. to subacute concentrations of hexavalent Cr (0.5, 1.0, 2.0, 4.0 ppm) after which the gills, midgut, hepatopancreas and antennal glands were examined for histopathological and ultrastructural changes. Pathological changes were greatest in the antennal glands, followed by hepatopancreas, gills and midgut. Severe changes occurred in some shrimp, even at 0.5 ppm Cr. Cells of all tissues frequently had swollen mitochondria and rough endoplasmic reticulum. Small, spherical or ring-like intranuclear inclusions, possibly indicative of cellular hyperactivity or manifestions of Cr and/or protein complexes, were most prevalent in the hepatopancreas and glands but also occurred in the midgut and gills. Other major degenerative changes in the antennal glands were restricted to the labyrinth and included diminution of basal plasmalemmal infoldings and cytoplasmic density, nuclear hypertrophy followed by widespread nuclear pyknosis and epithelial desquamation. In severely altered hepatopancreas hypertrophy was indicated for the basal laminae, nuclei and possibly for the nucleoli. There was an apparent reduction in mitotic events and many observed mitotic nuclei were abnormal. Abnormal midgut hypertrophy was present in only 8 of 20 examined shrimp, exposed to 0.5 and 1 ppm Cr. Further, the gills of only 10 of the 40 examined Cr-exposed shrimp possessed abnormal features detectable with light microscopy. Ultrastructural analysis of the latter indicated an increase in lysosomes and a decrease in cytoplasmic density. There was also a pronounced diminution in the degree of lamellar, subcuticular plasmalemmal infolding. This latter feature is postulated to be a mechanism for the regulation of Cr influx. Possible explanations for most observed alterations in the above tissues are proposed.","Histopathological and ultrastructural changes in the antennal gland, midgut, hepatopancreas and gill of grass shrimp (Palaemonetes pugio) following exposure to hexavalent chromium Abs: HEEP COPYRIGHT: BIOL ABS. Grass shrimp, P. pugio, were exposed for 1 mo. to subacute concentrations of hexavalent Cr (0.5, 1.0, 2.0, 4.0 ppm) after which the gills, midgut, hepatopancreas and antennal glands were examined for histopathological and ultrastructural changes. Pathological changes were greatest in the antennal glands, followed by hepatopancreas, gills and midgut. Severe changes occurred in some shrimp, even at 0.5 ppm Cr. Cells of all tissues frequently had swollen mitochondria and rough endoplasmic reticulum. Small, spherical or ring-like intranuclear inclusions, possibly indicative of cellular hyperactivity or manifestions of Cr and/or protein complexes, were most prevalent in the hepatopancreas and glands but also occurred in the midgut and gills. Other major degenerative changes in the antennal glands were restricted to the labyrinth and included diminution of basal plasmalemmal infoldings and cytoplasmic density, nuclear hypertrophy followed by widespread nuclear pyknosis and epithelial desquamation. In severely altered hepatopancreas hypertrophy was indicated for the basal laminae, nuclei and possibly for the nucleoli. There was an apparent reduction in mitotic events and many observed mitotic nuclei were abnormal. Abnormal midgut hypertrophy was present in only 8 of 20 examined shrimp, exposed to 0.5 and 1 ppm Cr. Further, the gills of only 10 of the 40 examined Cr-exposed shrimp possessed abnormal features detectable with light microscopy. Ultrastructural analysis of the latter indicated an increase in lysosomes and a decrease in cytoplasmic density. There was also a pronounced diminution in the degree of lamellar, subcuticular plasmalemmal infolding. This latter feature is postulated to be a mechanism for the regulation of Cr influx. Possible explanations for most observed alterations in the above tissues are proposed."
1514453,Doughtie et al. 1983,Cuticular lesions induced in grass shrimp (Palaemonetes pugio) exposed to hexavalent chromium,"HEEP COPYRIGHT: BIOL ABS. Adult grass shrimp were exposed to 0.5, 1.0, 2.0 and 4.0 ppm Cr6+ for 28 days. At the end of the exposure period, > 50% of the surviving shrimp possessed cuticular lesions that had many of the gross characteristics of shell disease. These lesions were usually associated with articulations of the appendages and abdomen. At increasing levels of Cr exposure, there was a proportionate increase in the loss of limbs such that ê 50% of the limbs were lost in grass shrimp exposed to the highest test concentration of Cr. Histological and ultrastructural examination of numerous lesions demonstrated a range of degenerative features within the subcuticular epithelium that included cytoplasmic vacuolization, mitochondrial swelling, chromatin emargination and the presence of unusual nuclear inclusions that appeared to indicate direct Cr toxicity. A marked retardation in new epicuticle and exocuticle formation was observed in viable tissues associated with lesions in late premolt shrimp. Cr interfered with the normal functions of subcuticular epithelium, particularly cuticle formation, and subsequently caused structural weaknesses or perforations to develop in the cuticle of newly moted shrimp. Because of these Cr-induced exoskeletal deficiencies, a viaduct for pathogenic organisms (e.g., bacteria) and direct Cr influx was formed that perpetuated lesion development.","Cuticular lesions induced in grass shrimp (Palaemonetes pugio) exposed to hexavalent chromium Abs: HEEP COPYRIGHT: BIOL ABS. Adult grass shrimp were exposed to 0.5, 1.0, 2.0 and 4.0 ppm Cr6+ for 28 days. At the end of the exposure period, > 50% of the surviving shrimp possessed cuticular lesions that had many of the gross characteristics of shell disease. These lesions were usually associated with articulations of the appendages and abdomen. At increasing levels of Cr exposure, there was a proportionate increase in the loss of limbs such that ê 50% of the limbs were lost in grass shrimp exposed to the highest test concentration of Cr. Histological and ultrastructural examination of numerous lesions demonstrated a range of degenerative features within the subcuticular epithelium that included cytoplasmic vacuolization, mitochondrial swelling, chromatin emargination and the presence of unusual nuclear inclusions that appeared to indicate direct Cr toxicity. A marked retardation in new epicuticle and exocuticle formation was observed in viable tissues associated with lesions in late premolt shrimp. Cr interfered with the normal functions of subcuticular epithelium, particularly cuticle formation, and subsequently caused structural weaknesses or perforations to develop in the cuticle of newly moted shrimp. Because of these Cr-induced exoskeletal deficiencies, a viaduct for pathogenic organisms (e.g., bacteria) and direct Cr influx was formed that perpetuated lesion development."
1514450,Dobos 2005,Lower limits coming for hexavalent chromium,"The Occupational Safety and Health Administration (OSHA) has established an 8-hour time-weighted average exposure limit of 1.0&micro;g/m3 in its proposed rule for hexavalent chromium, which is significantly lower than current levels applied in the manufacturing and construction industries. This article discusses the proposed changes and the implications of the rule for employers with respect to training, information, limitation of exposure, monitoring and medical supervision.","Lower limits coming for hexavalent chromium Abs: The Occupational Safety and Health Administration (OSHA) has established an 8-hour time-weighted average exposure limit of 1.0&micro;g/m3 in its proposed rule for hexavalent chromium, which is significantly lower than current levels applied in the manufacturing and construction industries. This article discusses the proposed changes and the implications of the rule for employers with respect to training, information, limitation of exposure, monitoring and medical supervision."
1514448,Djane et al. 1999,Chromium speciation in natural waters using serially connected supported liquid membranes,"BIOSIS COPYRIGHT: BIOL ABS. A supported liquid membrane (SLM) method for the speciation of chromium has been developed. The method is based on selective extraction and enrichment of anionic Cr(VI) and cationic Cr(III) species in two serially connected SLM units. Methyltricaprylammonium chloride (Aliquat) and di-(2-ethylhexyl) phosphoric acid (DEHPA), respectively were used as the selective extractants in the membrane liquid. Graphite furnace atomic absorption spectrometry (GFAAS) was utilised for final determination. Optim n surface water from an abandoned tannery site. Storage experiments at different pH showed that preservation at neutral pH gave almost constant values over a period of one month. At acidic pH (pH = 3.0) the concentration of Cr(VI) decreased rapidly while the concentration of Cr(III) increased. The detection limit, expressed as three times the standard deviation of enriched blank samples was 0.01 mug l-1.","Chromium speciation in natural waters using serially connected supported liquid membranes Abs: BIOSIS COPYRIGHT: BIOL ABS. A supported liquid membrane (SLM) method for the speciation of chromium has been developed. The method is based on selective extraction and enrichment of anionic Cr(VI) and cationic Cr(III) species in two serially connected SLM units. Methyltricaprylammonium chloride (Aliquat) and di-(2-ethylhexyl) phosphoric acid (DEHPA), respectively were used as the selective extractants in the membrane liquid. Graphite furnace atomic absorption spectrometry (GFAAS) was utilised for final determination. Optim n surface water from an abandoned tannery site. Storage experiments at different pH showed that preservation at neutral pH gave almost constant values over a period of one month. At acidic pH (pH = 3.0) the concentration of Cr(VI) decreased rapidly while the concentration of Cr(III) increased. The detection limit, expressed as three times the standard deviation of enriched blank samples was 0.01 mug l-1."
1514447,Dilek and  Yetis 1992,Effects of heavy metals on activated sludge process,Biosis copyright: biol abs. rrm wastewater treatment methods waste disposal growth rate microorganism toxicity performance,Effects of heavy metals on activated sludge process Abs: Biosis copyright: biol abs. rrm wastewater treatment methods waste disposal growth rate microorganism toxicity performance
1514446,Dilek et al. 1998,Combined effects of Ni(II) and Cr(VI) on activated sludge,"BIOSIS COPYRIGHT: BIOL ABS. The combined effects of Ni(II) and Cr(VI) on activated sludge kinetics were studied in this paper. The metals were added to a synthetic medium with a chemical oxygen demand (COD) of 1300 mg l-1 to give various combinations of Ni(II) and Cr(VI). Activated sludge performance, in terms of COD removal, was not adversely affected in an acclimatized culture by the metal combinations, compared with the single metals. The combination effects of Ni(II) and Cr(VI) on biokinetic constants, i.e. the maximum specific growth rate, mum, was found to be stimulatory in general. The same effect was observed on the half-saturation substrate concentration, Ks. Effects were therefore classified as synergistic with respect to these constants.","Combined effects of Ni(II) and Cr(VI) on activated sludge Abs: BIOSIS COPYRIGHT: BIOL ABS. The combined effects of Ni(II) and Cr(VI) on activated sludge kinetics were studied in this paper. The metals were added to a synthetic medium with a chemical oxygen demand (COD) of 1300 mg l-1 to give various combinations of Ni(II) and Cr(VI). Activated sludge performance, in terms of COD removal, was not adversely affected in an acclimatized culture by the metal combinations, compared with the single metals. The combination effects of Ni(II) and Cr(VI) on biokinetic constants, i.e. the maximum specific growth rate, mum, was found to be stimulatory in general. The same effect was observed on the half-saturation substrate concentration, Ks. Effects were therefore classified as synergistic with respect to these constants."
1514445,Dilek and  Gokcay 1996,Microbiology of activated sludge treating wastewater containing Ni(II) and Cr(VI),"BIOSIS COPYRIGHT: BIOL ABS. The species of microorganisms dominating a laboratory-scale once-through activated sludge unit treating simulated wastewater with different influent strengths (650 and 1300 mgl-1 COD) and containing 5 to 10 mgl-1 Ni(II) and 1 to 50 mgl-1 Cr(VI) were identified by standard biochemical tests. Within this framework, combinations of metals and influent COD concentrations were tried. Organisms, namely Proteus rettgeri, Acinetobacter sp., Flavobacterium lutescens, Bacillus cereus var. albolactis, Klebsiella sp., Arthrobacter simplex, and Pseudomonas mendocina, were identified at different stages of the experiments.","Microbiology of activated sludge treating wastewater containing Ni(II) and Cr(VI) Abs: BIOSIS COPYRIGHT: BIOL ABS. The species of microorganisms dominating a laboratory-scale once-through activated sludge unit treating simulated wastewater with different influent strengths (650 and 1300 mgl-1 COD) and containing 5 to 10 mgl-1 Ni(II) and 1 to 50 mgl-1 Cr(VI) were identified by standard biochemical tests. Within this framework, combinations of metals and influent COD concentrations were tried. Organisms, namely Proteus rettgeri, Acinetobacter sp., Flavobacterium lutescens, Bacillus cereus var. albolactis, Klebsiella sp., Arthrobacter simplex, and Pseudomonas mendocina, were identified at different stages of the experiments."
1514442,Dieter 1998,Proactive limit values for responsible management of chemicals: Part II: Defining proactive limit values,"BIOSIS COPYRIGHT: BIOL ABS. The Basic Rule of Environmental Hygiene BREH (DIETER 1996; 1998b) is a suitable starting point for proactive chemicals management. Three definitions (- IV) for corresponding proactive LVs can be derived from the BREH: (1) Functional anthropogenic exposure of the type residues = substance group B is accepted at least at a minimal technical threshold FB > 0 to maintain desired functionality distinctly below the most sensitive adverse effect threshold Ea, (0 < FB - LVB < Ea). (2) Group C exposure = non functional contaminants (FC = 0) is to be tolerated only at technically low if not ""zero"" levels TC, hence 0 = Fc < TC - LVC < | Ea. (3) Group A = natural exposure with neither a technical background nor defined functionality (NA = FA \ 0). It may be accepted or tolerated up to its upper limit NA | Ea, irrespective of how wide or narrow the margin of safety between both might be (0EH is not only a suitable starting point for finding proactive LVs, but also for","Proactive limit values for responsible management of chemicals: Part II: Defining proactive limit values Abs: BIOSIS COPYRIGHT: BIOL ABS. The Basic Rule of Environmental Hygiene BREH (DIETER 1996; 1998b) is a suitable starting point for proactive chemicals management. Three definitions (- IV) for corresponding proactive LVs can be derived from the BREH: (1) Functional anthropogenic exposure of the type residues = substance group B is accepted at least at a minimal technical threshold FB > 0 to maintain desired functionality distinctly below the most sensitive adverse effect threshold Ea, (0 < FB - LVB < Ea). (2) Group C exposure = non functional contaminants (FC = 0) is to be tolerated only at technically low if not ""zero"" levels TC, hence 0 = Fc < TC - LVC < | Ea. (3) Group A = natural exposure with neither a technical background nor defined functionality (NA = FA \ 0). It may be accepted or tolerated up to its upper limit NA | Ea, irrespective of how wide or narrow the margin of safety between both might be (0EH is not only a suitable starting point for finding proactive LVs, but also for"
1514439,Dharmawardene 1991,Finger clubbing in match factory workers in Fiji,"BIOSIS COPYRIGHT: BIOL ABS. This communication reports of two cases of digital clubbing in a factory manufacturing matches in Vitilevu, Fiji Islands. Both these cases were occupationally exposed to chemicals used in the manufacture of matches. They had physical contact with these chemicals including rhodamine B dye. Subjects who worked in the same factory area, including one worker who had FEV1.0 and FVC values below the predicted normal, but who did not handle chemicals showed no evidence of finger clubbing.","Finger clubbing in match factory workers in Fiji Abs: BIOSIS COPYRIGHT: BIOL ABS. This communication reports of two cases of digital clubbing in a factory manufacturing matches in Vitilevu, Fiji Islands. Both these cases were occupationally exposed to chemicals used in the manufacture of matches. They had physical contact with these chemicals including rhodamine B dye. Subjects who worked in the same factory area, including one worker who had FEV1.0 and FVC values below the predicted normal, but who did not handle chemicals showed no evidence of finger clubbing."
1514438,Dhakephalkar et al. 1996,Plasmid mediated chromate resistance and reduction in Pseudomonas mendocina MCM B-180,"BIOSIS COPYRIGHT: BIOL ABS. A chromate-resistant strain of Pseudomonas mendocina MCM B-180 capable of reducing hexavalent chromium was found to harbour a single plasmid. Incubation of the strain at 42ê C for 24 h caused loss of chromate resistance as well as the plasmid, pARI180. Transformation of E. coli DH5alpha with purified pARI180 plasmid DNA resulted in simultaneous acquisition of resistance to chromate and the appearance of plasmid in the transformants. Most importantly, the plasmid transfer was found to confer chromate reduction ability on to the E. coli transformants.","Plasmid mediated chromate resistance and reduction in Pseudomonas mendocina MCM B-180 Abs: BIOSIS COPYRIGHT: BIOL ABS. A chromate-resistant strain of Pseudomonas mendocina MCM B-180 capable of reducing hexavalent chromium was found to harbour a single plasmid. Incubation of the strain at 42ê C for 24 h caused loss of chromate resistance as well as the plasmid, pARI180. Transformation of E. coli DH5alpha with purified pARI180 plasmid DNA resulted in simultaneous acquisition of resistance to chromate and the appearance of plasmid in the transformants. Most importantly, the plasmid transfer was found to confer chromate reduction ability on to the E. coli transformants."
1514434,Devi et al. 1986,Photometric determination of chromium-vi,Biosis copyright: biol abs. rrm heavy metal,Photometric determination of chromium-vi Abs: Biosis copyright: biol abs. rrm heavy metal
1514432,Dennis et al. 1996,Reduction of Hexavalent Chromium Concentration in Fumes from Metal Cored Arc Welding by Addition of Reactive Metals,"Modifications have been made through the addition of active metals (aluminum, zinc, or magnesium) to metal cored arc welding wires in order to reduce the concentration of hexavalent chromium (7440473) in welding fumes. Test welding was performed for 10 to 20 seconds with the extractor fan operating a further 90 seconds in order to fully collect the generated fume. For all the experimental metal cored wires used in the study, an increase in fume formation rate with voltage was noted to be in the range of 17 to 25 volts (V). The lowest fume formation rate over the range of voltages tested was produced by the 1% aluminum wire. Aluminum also had the lowest ionization energy and therefore produced a more stable arc along with the lower fume formation rate. Wires containing 1% zinc produced the lowest chromium concentrations in the fume. When the voltage was increased above 18V, the advantages of the zinc wire were not sustained. Above the 21V level, the formation rate for the fume and the concentration of chromium was above control levels. The authors conclude that adding 1% of reactive metals to welding wires reduced the mass of fume produced and the amount of chromium contained in that fume.","Reduction of Hexavalent Chromium Concentration in Fumes from Metal Cored Arc Welding by Addition of Reactive Metals Abs: Modifications have been made through the addition of active metals (aluminum, zinc, or magnesium) to metal cored arc welding wires in order to reduce the concentration of hexavalent chromium (7440473) in welding fumes. Test welding was performed for 10 to 20 seconds with the extractor fan operating a further 90 seconds in order to fully collect the generated fume. For all the experimental metal cored wires used in the study, an increase in fume formation rate with voltage was noted to be in the range of 17 to 25 volts (V). The lowest fume formation rate over the range of voltages tested was produced by the 1% aluminum wire. Aluminum also had the lowest ionization energy and therefore produced a more stable arc along with the lower fume formation rate. Wires containing 1% zinc produced the lowest chromium concentrations in the fume. When the voltage was increased above 18V, the advantages of the zinc wire were not sustained. Above the 21V level, the formation rate for the fume and the concentration of chromium was above control levels. The authors conclude that adding 1% of reactive metals to welding wires reduced the mass of fume produced and the amount of chromium contained in that fume."
1514430,Demirata et al. 1996,Separation of Cr(III) and Cr(VI) using melamine-formaldehyde resin and determination of both species in water by FAAS,"BIOSIS COPYRIGHT: BIOL ABS. A method is described for the determination of Cr(VI) and total chromium by FAAS. Cr(VI) is separated from Cr(III) by adsorption on melamine-formaldehyde resin. After elution of Cr(VI) with 0.1 mol/l NaAc solution, it is analysed by FAAS. Total chromium is determined by FAAS after conversion of Cr(III) to Cr(VI) by oxidation with hydrogen peroxide, total Cr(VI) is concentrated as above. If the total concentration of chromium is sufficient, the determination can be directly made by FAAS. Cr(III) can then be calculated by subtracting Cr(VI) from the total Cr. This method was successfully applied to the determination of chromium in lake water.","Separation of Cr(III) and Cr(VI) using melamine-formaldehyde resin and determination of both species in water by FAAS Abs: BIOSIS COPYRIGHT: BIOL ABS. A method is described for the determination of Cr(VI) and total chromium by FAAS. Cr(VI) is separated from Cr(III) by adsorption on melamine-formaldehyde resin. After elution of Cr(VI) with 0.1 mol/l NaAc solution, it is analysed by FAAS. Total chromium is determined by FAAS after conversion of Cr(III) to Cr(VI) by oxidation with hydrogen peroxide, total Cr(VI) is concentrated as above. If the total concentration of chromium is sufficient, the determination can be directly made by FAAS. Cr(III) can then be calculated by subtracting Cr(VI) from the total Cr. This method was successfully applied to the determination of chromium in lake water."
1514429,Deleo and  Ehrlich 1994,Reduction of hexavalent chromium by Pseudomonas fluorescens LB300 in batch and continuous cultures,"BIOSIS COPYRIGHT: BIOL ABS. Batch and continuous cultures of Pseudomonas fluorescens LB300 were shown to reduce hexavalent chromium, Cr(VI), aerobically at neutral pH (pH 7.0) with citrate as carbon and energy source. The product of Cr(VI) reduction was previously shown and confirmed in this work to be trivalent chromium, Cr(III), by quantitative reoxidation to Cr(VI) with KMnO4. In separate batch cultures (100 ml) containing initial Cr(VI) concentrations of 314.0, 200.0 and 112.5 mg Cr(VI) L-1, the organism reduced 61%, 69% and 99.7% of the Cr(VI), respectively. In a comparison of stationary and shaken cultures, the organism reduced 81% of Cr(VI) in 147 h in stationary culture and 80% in 122 h in shaken culture. In continuous culture, the organism lowered the influent Cr(VI) concentration by 28% with an 11.7-h residence time, by 39% with a 20.8-h residence time and by 57% with a 38.5-h residence time. A mass balance of chromium in a continuous culture at steady state showed an insignificant uptak","Reduction of hexavalent chromium by Pseudomonas fluorescens LB300 in batch and continuous cultures Abs: BIOSIS COPYRIGHT: BIOL ABS. Batch and continuous cultures of Pseudomonas fluorescens LB300 were shown to reduce hexavalent chromium, Cr(VI), aerobically at neutral pH (pH 7.0) with citrate as carbon and energy source. The product of Cr(VI) reduction was previously shown and confirmed in this work to be trivalent chromium, Cr(III), by quantitative reoxidation to Cr(VI) with KMnO4. In separate batch cultures (100 ml) containing initial Cr(VI) concentrations of 314.0, 200.0 and 112.5 mg Cr(VI) L-1, the organism reduced 61%, 69% and 99.7% of the Cr(VI), respectively. In a comparison of stationary and shaken cultures, the organism reduced 81% of Cr(VI) in 147 h in stationary culture and 80% in 122 h in shaken culture. In continuous culture, the organism lowered the influent Cr(VI) concentration by 28% with an 11.7-h residence time, by 39% with a 20.8-h residence time and by 57% with a 38.5-h residence time. A mass balance of chromium in a continuous culture at steady state showed an insignificant uptak"
1514428,Deleo and  Ehrlich 1993,Reduction of hexavalent chromium by pseudomonas-fluorescens lb300,Biosis copyright: biol abs. rrm abstract chromate pollutant waste treatment trivalent chromium oxygen concentration,Reduction of hexavalent chromium by pseudomonas-fluorescens lb300 Abs: Biosis copyright: biol abs. rrm abstract chromate pollutant waste treatment trivalent chromium oxygen concentration
1514427,Deepak and  Gupta 1991,Hexavalent chromium removal from wastewater,"BIOSIS COPYRIGHT: BIOL ABS. Reduction, precipitation and adsorption processes have been studied for the removal of Cr+6 from synthetic wastewater. Results indicated that sulphide precipitation process using H2S gas was more efficient than other processes.","Hexavalent chromium removal from wastewater Abs: BIOSIS COPYRIGHT: BIOL ABS. Reduction, precipitation and adsorption processes have been studied for the removal of Cr+6 from synthetic wastewater. Results indicated that sulphide precipitation process using H2S gas was more efficient than other processes."
1514422,Davoli and  Guglielmi 1999,Response of sOUR and AUR to heavy metal contamination in activated sludge. AU - MADONI P,"BIOSIS COPYRIGHT: BIOL ABS. The aim of this work was to make a contribution to the knowledge of inhibition by heavy metals of both nitrifying and heterotrophic bacteria in the activated sludge, based on measurements of ammonium uptake rate (AUR) and oxygen uptake rate (sOUR) activities. For the inhibition tests, we used different concentrations of the following heavy metals: Cd2+, Cr6+, Cu2+, Pb2+ and Zn2+, and the toxic effect of each metal was measured after 1 and 24 h exposure. Tests were performed on activated sludgesheavy metals in comparison with heterotrophs.Inhibitory effects of Cr6+ and Zn2+, were quite similar on both AUR and sOUR activity. Our results suggest that in nitrifying activated sludge plants the sOUR test can be used better than AUR test to identify possible inhibitory effects of heavy metals from wastewater.","Response of sOUR and AUR to heavy metal contamination in activated sludge. AU - MADONI P Abs: BIOSIS COPYRIGHT: BIOL ABS. The aim of this work was to make a contribution to the knowledge of inhibition by heavy metals of both nitrifying and heterotrophic bacteria in the activated sludge, based on measurements of ammonium uptake rate (AUR) and oxygen uptake rate (sOUR) activities. For the inhibition tests, we used different concentrations of the following heavy metals: Cd2+, Cr6+, Cu2+, Pb2+ and Zn2+, and the toxic effect of each metal was measured after 1 and 24 h exposure. Tests were performed on activated sludgesheavy metals in comparison with heterotrophs.Inhibitory effects of Cr6+ and Zn2+, were quite similar on both AUR and sOUR activity. Our results suggest that in nitrifying activated sludge plants the sOUR test can be used better than AUR test to identify possible inhibitory effects of heavy metals from wastewater."
1514421,Davis et al. 1991,Chemical processes affecting the transport of chromium-vi in groundwater,Biosis copyright: biol abs. rrm abstract heavy metal toxicity chromium reduction field tracer test laboratory experiment aquifer,Chemical processes affecting the transport of chromium-vi in groundwater Abs: Biosis copyright: biol abs. rrm abstract heavy metal toxicity chromium reduction field tracer test laboratory experiment aquifer
1514418,Das et al. 1991,"Transformation of added chromium(III) and chromium(VI) in flooded soils amended with iron, manganese and glucose","BIOSIS COPYRIGHT: BIOL ABS. The transformation of added Cr (iii) and Cr (vi) as influenced by Fe2+, Fe3+, Mn2+ and Mn4+. with or without glucose addition under varying periods of flooding was studied in three soils viz, inceptisol, vertisol and utisol. The results showed that the concentration of Cr (vi), a form toxic to plants in soil solution decreased with flooding and the decrease was further hastened in the presence of glucose and Fe2+. The ability of these soils to revert soluble Cr to unavailable form was in the order: vertisol > inceptisol > ultisol.","Transformation of added chromium(III) and chromium(VI) in flooded soils amended with iron, manganese and glucose Abs: BIOSIS COPYRIGHT: BIOL ABS. The transformation of added Cr (iii) and Cr (vi) as influenced by Fe2+, Fe3+, Mn2+ and Mn4+. with or without glucose addition under varying periods of flooding was studied in three soils viz, inceptisol, vertisol and utisol. The results showed that the concentration of Cr (vi), a form toxic to plants in soil solution decreased with flooding and the decrease was further hastened in the presence of glucose and Fe2+. The ability of these soils to revert soluble Cr to unavailable form was in the order: vertisol > inceptisol > ultisol."
1514417,Dar and  Shakoori 1999,Chromium tolerant yeast strains isolated from industrial effluents and their possible use in environmental clean-up,Biosis copyright: biol abs. rrm chromium tolerant yeast strains isolated from industrial effluents and their possible use in environmental clean-upyresearch article yeast toxicology ecotoxicology industrial effluents environmental clean-up bioprocess engineering environmental metal toxicity industrialization chromium(vi) pollutant metal deposition carcinogen toxin bioremediation cell damage physiology pollution,Chromium tolerant yeast strains isolated from industrial effluents and their possible use in environmental clean-up Abs: Biosis copyright: biol abs. rrm chromium tolerant yeast strains isolated from industrial effluents and their possible use in environmental clean-upyresearch article yeast toxicology ecotoxicology industrial effluents environmental clean-up bioprocess engineering environmental metal toxicity industrialization chromium(vi) pollutant metal deposition carcinogen toxin bioremediation cell damage physiology pollution
1514416,Daniels and  Gunter 1843,"Health Hazard Evaluation Report No. HETA-86-063-1843, Olson Industries, Denver, Colorado","In response to a request from Olson Industries (SIC-3471), Denver, Colorado, a study was made of employee exposures to electroplating, machine, spot welding, and soldering chemicals in use at the facility. Determinations were made for chromium (7440473) and hexavalent chromium (18540299), nickel (7440020), 1,1,1-trichloroethane (71556), sulfuric-acid (7664939), hydrochloric-acid (7647010), oil mists, and trace metals in personal and area air samples. At the time of the survey, none of the detected levels exceeded the established limits from OSHA, NIOSH, or the American Conference of Governmental Industrial Hygienists. However, it was cautioned that continued examination of the ventilation system be performed to ensure its proper working, particularly in the area of the chromic-acid (1333820) tanks with their potential generation of substantial mist. It was also suggested that chromium exposures be reduced to as low a level as possible due to the suspicion of excess cancer mortality rates among chrome platers. Face shields, chemical goggles, splash aprons, arm coverings, gloves, and boots should be available for employees working in chemical mixing and addition jobs. Good work practices and personal hygiene should be stressed.","Health Hazard Evaluation Report No. HETA-86-063-1843, Olson Industries, Denver, Colorado Abs: In response to a request from Olson Industries (SIC-3471), Denver, Colorado, a study was made of employee exposures to electroplating, machine, spot welding, and soldering chemicals in use at the facility. Determinations were made for chromium (7440473) and hexavalent chromium (18540299), nickel (7440020), 1,1,1-trichloroethane (71556), sulfuric-acid (7664939), hydrochloric-acid (7647010), oil mists, and trace metals in personal and area air samples. At the time of the survey, none of the detected levels exceeded the established limits from OSHA, NIOSH, or the American Conference of Governmental Industrial Hygienists. However, it was cautioned that continued examination of the ventilation system be performed to ensure its proper working, particularly in the area of the chromic-acid (1333820) tanks with their potential generation of substantial mist. It was also suggested that chromium exposures be reduced to as low a level as possible due to the suspicion of excess cancer mortality rates among chrome platers. Face shields, chemical goggles, splash aprons, arm coverings, gloves, and boots should be available for employees working in chemical mixing and addition jobs. Good work practices and personal hygiene should be stressed."
1514415,Dahab and  Al-Madfa 1997,Chromium distribution in waters and sediments of the eastern side of the Qatari Peninsula,"BIOSIS COPYRIGHT: BIOL ABS. The coastal environment on the eastern side of the Qatari peninsula is subjected to several sources of pollution such as the leaching from a solid waste disposal site, the merchant and naval harbours of Doha and surface water discharge outlets. Chromium was measured in surface sea water and in surficial sediments by graphite furnace atomic absorption spectrophotometry (GFAAS). Average Cr concentrations in the investigated waters during the period of study were 0.08, 0.66 and 0.54 mug l-1, respectively, for Cr (III), Cr (VI), and particulate phases. The areal distribution of Cr in the studied waters reflected the impact of the leachate from the solid waste disposal site, the surface water discharge and the two harbours in the area. Cr concentrations in the investigated sediments ranged from 11.6 to 46.5 mug g-1 dry wt. with an average of 25.4 | 8.7 mug g-1 dry wt. Elevated Cr levels were identified in the sediments around the solid waste disposal site ( > 40 mug g-1 d","Chromium distribution in waters and sediments of the eastern side of the Qatari Peninsula Abs: BIOSIS COPYRIGHT: BIOL ABS. The coastal environment on the eastern side of the Qatari peninsula is subjected to several sources of pollution such as the leaching from a solid waste disposal site, the merchant and naval harbours of Doha and surface water discharge outlets. Chromium was measured in surface sea water and in surficial sediments by graphite furnace atomic absorption spectrophotometry (GFAAS). Average Cr concentrations in the investigated waters during the period of study were 0.08, 0.66 and 0.54 mug l-1, respectively, for Cr (III), Cr (VI), and particulate phases. The areal distribution of Cr in the studied waters reflected the impact of the leachate from the solid waste disposal site, the surface water discharge and the two harbours in the area. Cr concentrations in the investigated sediments ranged from 11.6 to 46.5 mug g-1 dry wt. with an average of 25.4 | 8.7 mug g-1 dry wt. Elevated Cr levels were identified in the sediments around the solid waste disposal site ( > 40 mug g-1 d"
1514413,Czako-Ver et al. 1999,Characterization of Schizosaccharomyces pombe chromium(VI)-sensitive and resistant mutants,Biosis copyright: biol abs. rrm characterization of $schizosaccharomyces $pombe chromium(vi)-sensitive and resistant mutantsymeeting abstract meeting poster schizosaccharomyces pombe strain-lys1-131h-plus strain-crw-6 strain-leu1-32h-negative strain-crw-9 strain characterization chromium vi mutant sensitivity toxin toxicology genetics,Characterization of Schizosaccharomyces pombe chromium(VI)-sensitive and resistant mutants Abs: Biosis copyright: biol abs. rrm characterization of $schizosaccharomyces $pombe chromium(vi)-sensitive and resistant mutantsymeeting abstract meeting poster schizosaccharomyces pombe strain-lys1-131h-plus strain-crw-6 strain-leu1-32h-negative strain-crw-9 strain characterization chromium vi mutant sensitivity toxin toxicology genetics
1514412,Cushnie 1984,Navy electroplating pollution control technology assessment manual,"HMTC The Navy Electroplating Pollution Control Technology Assessment Manual provides design and cost information for pollution control technologies. The pollution/water reduction section includes in-plant techniques used to reduce chemical purchases, water use, wastewater treatment needs, and disposal costs. The conventional treatment technologies discussed are hexavalent chromium reduction using sulfur dioxide, cyanide oxidation by alkali chlorination, hydroxide precipitation, flocculation/clarification, and solids separation. Substitute treatment technologies as possible alternatives to conventional treatments are summarized. Material recovery technologies have been designed as a result of pollution control legislation that penalizes facilities for insufficient raw material usage. Tables are included. (53 ref.)","Navy electroplating pollution control technology assessment manual Abs: HMTC The Navy Electroplating Pollution Control Technology Assessment Manual provides design and cost information for pollution control technologies. The pollution/water reduction section includes in-plant techniques used to reduce chemical purchases, water use, wastewater treatment needs, and disposal costs. The conventional treatment technologies discussed are hexavalent chromium reduction using sulfur dioxide, cyanide oxidation by alkali chlorination, hydroxide precipitation, flocculation/clarification, and solids separation. Substitute treatment technologies as possible alternatives to conventional treatments are summarized. Material recovery technologies have been designed as a result of pollution control legislation that penalizes facilities for insufficient raw material usage. Tables are included. (53 ref.)"
1514411,Cuesta et al. 1996,Flow injection method for the rapid determination of Chemical Oxygen Demand based on microwave digestion and chromium speciation in flame atomic absorption spectrometry,"BIOSIS COPYRIGHT: BIOL ABS. The present paper describes a new flow injection method for the determination of Chemical Oxygen Demand (COD). This method consists of a first digestion step, where the sample is heated by microwave radiation, a second one where an anionic exchange resin retains the Cr(VI) that has not been reduced by the organic matter of the sample and a third one where Cr(VI), after being eluted, is determined by flame atomic absorption spectrometry. The microwave power applied, the sulphuric acid concentration, the liquid flow in the digestion step and the sample volume were the variables studied. The recovery and precision obtained with this method are similar to those obtained using a standard semi-micro method, whereas the throughput is much higher (up to 50 determinations per hour). As regards sensitivity, by changing the sample loop volume and the concentration of dichromate, one can analyze samples with Chemical Oxygen Demand values between 25 and 5000 mg/l. The limit of detec","Flow injection method for the rapid determination of Chemical Oxygen Demand based on microwave digestion and chromium speciation in flame atomic absorption spectrometry Abs: BIOSIS COPYRIGHT: BIOL ABS. The present paper describes a new flow injection method for the determination of Chemical Oxygen Demand (COD). This method consists of a first digestion step, where the sample is heated by microwave radiation, a second one where an anionic exchange resin retains the Cr(VI) that has not been reduced by the organic matter of the sample and a third one where Cr(VI), after being eluted, is determined by flame atomic absorption spectrometry. The microwave power applied, the sulphuric acid concentration, the liquid flow in the digestion step and the sample volume were the variables studied. The recovery and precision obtained with this method are similar to those obtained using a standard semi-micro method, whereas the throughput is much higher (up to 50 determinations per hour). As regards sensitivity, by changing the sample loop volume and the concentration of dichromate, one can analyze samples with Chemical Oxygen Demand values between 25 and 5000 mg/l. The limit of detec"
1514409,Criteria Group for Occupational Standards 1993,Criteria document for Swedish occupational standards. Chromium,"The scientific literature on untoward effects of exposure to various chromium compounds is reviewed. The carcinogenic and allergic effects resulting from exposure to various chromium compounds are emphasized. Those untoward effects considered to be of greatest significance for the exposed are emphasized; e.g. cancer and allergy. Results presented in the literature indicates that only those subjects who are exposed to hexavalent chromium compounds are at excess risk of developing cancer, and that the excess cancer risk is mainly related to the respiratory organs, further that water soluble compounds are more potent human carcinogens than are those with low solubility. The versatility of biological monitoring of subjects exposed to chromium has briefly been reviewed.","Criteria document for Swedish occupational standards. Chromium Abs: The scientific literature on untoward effects of exposure to various chromium compounds is reviewed. The carcinogenic and allergic effects resulting from exposure to various chromium compounds are emphasized. Those untoward effects considered to be of greatest significance for the exposed are emphasized; e.g. cancer and allergy. Results presented in the literature indicates that only those subjects who are exposed to hexavalent chromium compounds are at excess risk of developing cancer, and that the excess cancer risk is mainly related to the respiratory organs, further that water soluble compounds are more potent human carcinogens than are those with low solubility. The versatility of biological monitoring of subjects exposed to chromium has briefly been reviewed."
1514408,Occupational 1993,Scientific basis for Swedish Occupational Standards. XIV. Consensus report for chromium,Conclusions: The critical effect of occupational exposure to hexavalent chromium compounds is cancer. These compounds are also skin-sensitizing with direct contact. There are no data that would serve to indicate a critical effect for exposure to metallic chromium or chromium compounds with valences other than six.,Scientific basis for Swedish Occupational Standards. XIV. Consensus report for chromium Abs: Conclusions: The critical effect of occupational exposure to hexavalent chromium compounds is cancer. These compounds are also skin-sensitizing with direct contact. There are no data that would serve to indicate a critical effect for exposure to metallic chromium or chromium compounds with valences other than six.
1514407,Cox and  Linton 1985,Determination of Chromium Speciation in Environmental Particles. Multitechnique Study of Ferrochrome Smelter Dust,"A novel analytical procedure for the determination of the concentration, speciation and potential bioavailability of environmental chromium (7440473) (Cr) was presented, using samples obtained from a ferrochrome smelter dust deposit. Instrumental neutron activation analysis was performed on the initial primary sample, yielding a result of 55 milligrams per gram (mg/g) of Cr. This was decreased to 27.7mg/g after acid and alkali treatment, indicating that only 50 percent of the total Cr is bioavailable. Of various wet chemical techniques for extraction, the lithium-borate fusion method gave the highest yield for total Cr of 48 milligrams per gram, but did not give chemical state information. However, information on speciation was retained by a method of alkaline extraction, and using this method, 40 percent of the bioavailable Cr was estimated to be Cr(6+). Microscopic studies using scanning electron microscopy energy dispersive X-ray microanalysis, and surface chemical analysis via X-ray photoelectron spectroscopy were also performed. These microscopic studies revealed that the Cr(6+) exists mostly as Cr2O7(2-) or CrO4(2-) and is mostly found in submicron particles, while the remaining Cr is present as insoluble Cr2O3 within large particles similar to the original chromite ore","Determination of Chromium Speciation in Environmental Particles. Multitechnique Study of Ferrochrome Smelter Dust Abs: A novel analytical procedure for the determination of the concentration, speciation and potential bioavailability of environmental chromium (7440473) (Cr) was presented, using samples obtained from a ferrochrome smelter dust deposit. Instrumental neutron activation analysis was performed on the initial primary sample, yielding a result of 55 milligrams per gram (mg/g) of Cr. This was decreased to 27.7mg/g after acid and alkali treatment, indicating that only 50 percent of the total Cr is bioavailable. Of various wet chemical techniques for extraction, the lithium-borate fusion method gave the highest yield for total Cr of 48 milligrams per gram, but did not give chemical state information. However, information on speciation was retained by a method of alkaline extraction, and using this method, 40 percent of the bioavailable Cr was estimated to be Cr(6+). Microscopic studies using scanning electron microscopy energy dispersive X-ray microanalysis, and surface chemical analysis via X-ray photoelectron spectroscopy were also performed. These microscopic studies revealed that the Cr(6+) exists mostly as Cr2O7(2-) or CrO4(2-) and is mostly found in submicron particles, while the remaining Cr is present as insoluble Cr2O3 within large particles similar to the original chromite ore"
1514406,Cox 1986,"Industrial Hygiene Survey Report of Plateau, Incorporated, Bloomfield Refinery, Bloomfield, NM, Report No. IWS-124-10","Turnaround operations at a fluid catalytic cracking unit at the Bloomfield Refinery (SIC-1799) in Bloomfield, New Mexico, were investigated for possible exposure of workers to various chemical agents, including hexavalent chromium (7440473), coal tar pitch volatiles (CTPV), nitrogen-dioxide (10102440), sulfur-dioxide (7446095), respirable dusts, and welding fumes. The average level of nitrogen-dioxide in the air was 1.5 parts per million (ppm); the value for sulfur-dioxide was 2.5ppm. NIOSH standards for hexavalent chromium (0.025mg/m3 for water soluble and 0.001mg/m3 for water insoluble) were exceeded. Respirable dust levels above 5mg/m3 were noted during cleaning operations. In many welding steps the concentration of welding fumes was in excess of 5mg/m3 as well. At the plasma arc cutting operation, concentrations of carbon-monoxide (630080), nitrogen-dioxide, and sulfur-dioxide (airborne) were 11.1, 1.5, and 2.5ppm, respectively. During the removal of coke from the reactor, CTPV levels exceeded the standard of 0.1mg/m3. A hydrocarbon concentration of 263ppm was obtained during the reconditioning of a pump. Nearly normal levels of 9.3, 45.7, and 74.1ppm were noted during more normal turnaround conditions. The author recommended that monitoring of the air be undertaken on a regular basis and that protective clothing and equipment be used by the workers. Ventilation rates and the direction of the ventilation should be checked.","Industrial Hygiene Survey Report of Plateau, Incorporated, Bloomfield Refinery, Bloomfield, NM, Report No. IWS-124-10 Abs: Turnaround operations at a fluid catalytic cracking unit at the Bloomfield Refinery (SIC-1799) in Bloomfield, New Mexico, were investigated for possible exposure of workers to various chemical agents, including hexavalent chromium (7440473), coal tar pitch volatiles (CTPV), nitrogen-dioxide (10102440), sulfur-dioxide (7446095), respirable dusts, and welding fumes. The average level of nitrogen-dioxide in the air was 1.5 parts per million (ppm); the value for sulfur-dioxide was 2.5ppm. NIOSH standards for hexavalent chromium (0.025mg/m3 for water soluble and 0.001mg/m3 for water insoluble) were exceeded. Respirable dust levels above 5mg/m3 were noted during cleaning operations. In many welding steps the concentration of welding fumes was in excess of 5mg/m3 as well. At the plasma arc cutting operation, concentrations of carbon-monoxide (630080), nitrogen-dioxide, and sulfur-dioxide (airborne) were 11.1, 1.5, and 2.5ppm, respectively. During the removal of coke from the reactor, CTPV levels exceeded the standard of 0.1mg/m3. A hydrocarbon concentration of 263ppm was obtained during the reconditioning of a pump. Nearly normal levels of 9.3, 45.7, and 74.1ppm were noted during more normal turnaround conditions. The author recommended that monitoring of the air be undertaken on a regular basis and that protective clothing and equipment be used by the workers. Ventilation rates and the direction of the ventilation should be checked."
1514405,Cox 1984,"Industrial Hygiene Survey Report of Dorchester Refining Company, Mt. Pleasant, Texas, Report No. IWS-124-11","A survey was presented which attempted to characterized the exposure of turn around workers to various chemical agents. Over 40 chemicals were identified and quantified during this evaluation. Chemicals having the most potential for exposure in excess of current standards included nitrogen-dioxide (10102440) (NO2), chromium(VI) (18540299), nickel (7440020) (Ni), and coal-tar pitch volatiles (CTPVs). NO2 concentrations ranged from 10.0 to 321.1 parts per million (ppm), with a geometric mean of 35.2ppm at various welding operations. The OSHA time weighted average exposure limit has been listed as 5ppm. Air concentrations of hexavalent chromium compounds were noted to be in excess of the NIOSH recommended standards, 0.025mg/m3 for water soluble and 0.001mg/m3 for certain water insoluble forms, at welding operations. Ni air concentrations were in excess of the NIOSH recommended limits, 0.015 mg/m3 for metal and soluble compounds, at welding operations, reactor cleaning operations, kiln cleaning operations and in catalyst cleaning operations. CTPVs in air were in excess of the 0.1mg/m3 at residual cleaning operations. This survey also provided recommendations for air monitoring, use of protective clothing and equipment, checking of ventilation rates and directions and evaluation of work practices.","Industrial Hygiene Survey Report of Dorchester Refining Company, Mt. Pleasant, Texas, Report No. IWS-124-11 Abs: A survey was presented which attempted to characterized the exposure of turn around workers to various chemical agents. Over 40 chemicals were identified and quantified during this evaluation. Chemicals having the most potential for exposure in excess of current standards included nitrogen-dioxide (10102440) (NO2), chromium(VI) (18540299), nickel (7440020) (Ni), and coal-tar pitch volatiles (CTPVs). NO2 concentrations ranged from 10.0 to 321.1 parts per million (ppm), with a geometric mean of 35.2ppm at various welding operations. The OSHA time weighted average exposure limit has been listed as 5ppm. Air concentrations of hexavalent chromium compounds were noted to be in excess of the NIOSH recommended standards, 0.025mg/m3 for water soluble and 0.001mg/m3 for certain water insoluble forms, at welding operations. Ni air concentrations were in excess of the NIOSH recommended limits, 0.015 mg/m3 for metal and soluble compounds, at welding operations, reactor cleaning operations, kiln cleaning operations and in catalyst cleaning operations. CTPVs in air were in excess of the 0.1mg/m3 at residual cleaning operations. This survey also provided recommendations for air monitoring, use of protective clothing and equipment, checking of ventilation rates and directions and evaluation of work practices."
1514402,Cotta Ramusino et al. 1981,Influence of chromium vi upon stream ephemeroptera in the prealps,Heep copyright: biol abs. epeorus-torrentium rhithrogena-semicolorata ecdyonurus-helveticus habrophlebia-umbratilis baetis-rhodani baetis-gemellus,Influence of chromium vi upon stream ephemeroptera in the prealps Abs: Heep copyright: biol abs. epeorus-torrentium rhithrogena-semicolorata ecdyonurus-helveticus habrophlebia-umbratilis baetis-rhodani baetis-gemellus
1514401,Cornwell and  Hodgson 1982,"Health Hazard Evaluation Determination Report, No. MHETA-81-108-9006, Consolidation Coal Company, Central Machine Shop 20, Cadiz, Ohio","Employee exposure to welding fumes and solvents at the Consolidation Coal Company Central Machine Shop 20 (SIC-1211), Cadiz, Ohio, was investigated. The Mine Safety and Health Administration (MSHA) requested the study following worker reports of alleged excessive morbidity and mortality. The study was performed on February 22 to 24, 1982. About 75 individuals were employed at the shop. Personal and area air samples were collected. Airborne concentrations of manganese (7439965), iron (7439896), fluorides, ozone (10028156), nitrogen-dioxide (10102440), and carbon-monoxide (630080) were below applicable NIOSH recommended limits. Twenty percent of the samples for chromium (VI) (18540299) exceeded or equaled the NIOSH standard of 0.001 milligrams per cubic meter (mg/m3), having values of 0.002 and 0.001mg/m3. Three of eight nickel (7440020) samples obtained for welders in the blacksmith shop showed time weighted averages of airborne nickel in excess of the NIOSH standard of 0.015mg/m3. The authors conclude that welders in the blacksmith shop are exposed to chromium(VI) and nickel, both of which are carcinogenic. Recommendations include improved ventilation systems, use of metal fume respirators and tinted spectacles, and worker education.","Health Hazard Evaluation Determination Report, No. MHETA-81-108-9006, Consolidation Coal Company, Central Machine Shop 20, Cadiz, Ohio Abs: Employee exposure to welding fumes and solvents at the Consolidation Coal Company Central Machine Shop 20 (SIC-1211), Cadiz, Ohio, was investigated. The Mine Safety and Health Administration (MSHA) requested the study following worker reports of alleged excessive morbidity and mortality. The study was performed on February 22 to 24, 1982. About 75 individuals were employed at the shop. Personal and area air samples were collected. Airborne concentrations of manganese (7439965), iron (7439896), fluorides, ozone (10028156), nitrogen-dioxide (10102440), and carbon-monoxide (630080) were below applicable NIOSH recommended limits. Twenty percent of the samples for chromium (VI) (18540299) exceeded or equaled the NIOSH standard of 0.001 milligrams per cubic meter (mg/m3), having values of 0.002 and 0.001mg/m3. Three of eight nickel (7440020) samples obtained for welders in the blacksmith shop showed time weighted averages of airborne nickel in excess of the NIOSH standard of 0.015mg/m3. The authors conclude that welders in the blacksmith shop are exposed to chromium(VI) and nickel, both of which are carcinogenic. Recommendations include improved ventilation systems, use of metal fume respirators and tinted spectacles, and worker education."
1514399,Cooperman 1966,Maximal Permissible Concentration of Hexavalent Chromium in Atmospheric Air,"Air pollution with hexavalent chromium is studied to determine its maximum permissible concentration in ambient air. Results indicate that inhalation of air containing 10 to 24 microns per cubic meter, even for a brief period of time, produces sharp irritation in the nostrils, and lower concentrations produce slight irritation of the upper respiratory tract. A concentration of 2.5 microns per cubic meter of hexavalent chromium in the air is determined as the threshold of reflex chromium (7440473) aerosol effect on the functional state of the cerebral cortex, for persons of the highest perception sensitivity. The existing maximum permissible concentration for hexavalent chromium, namely, 0.1 milligram per cubic meter, is considered too high and a revision to a lower level is recommended.","Maximal Permissible Concentration of Hexavalent Chromium in Atmospheric Air Abs: Air pollution with hexavalent chromium is studied to determine its maximum permissible concentration in ambient air. Results indicate that inhalation of air containing 10 to 24 microns per cubic meter, even for a brief period of time, produces sharp irritation in the nostrils, and lower concentrations produce slight irritation of the upper respiratory tract. A concentration of 2.5 microns per cubic meter of hexavalent chromium in the air is determined as the threshold of reflex chromium (7440473) aerosol effect on the functional state of the cerebral cortex, for persons of the highest perception sensitivity. The existing maximum permissible concentration for hexavalent chromium, namely, 0.1 milligram per cubic meter, is considered too high and a revision to a lower level is recommended."
1514396,Conroy et al. 1995,Workplace Emission Factors for Hexavalent Chromium Plating,"A methodology for determining workroom hexavalent-chromium (18540299) (Cr+6) emissions during chromium plating processes was described. The approach was based on collecting area particulate samples at various distances from a Cr+6 emission source along with measurements of the ventilation rate. The samples were analyzed for Cr+6 by proton induced X-ray emission spectroscopy. These data were transformed to emission rates and factors using a multipoint diffusion mass balance model in conjunction with variables that were specific to the geometry and patterns of work in the workspace. The method was applied to determining Cr+6 emission rates and factors in an electroplating shop where aluminum pistons were plated with chromium (7440473). Hourly Cr+6 emissions measured 49.6, 137, and 249 inches from the piston line varied from 1.09 to 8.59, 0.35 to 4.71, and 0.20 to 3.32 micrograms per cubic meter (microg/m3), respectively. All were below the American Conference of Governmental Industrial Hygienists Cr+6 standard of 50microg/m3. Baseline Cr+6 emissions averaged around 0.04 to 0.31microg/m3. Total chromium emissions were significantly related to the ampere hours (A-hr) of chromium plating. This yielded a Cr+6 emission factor of 0.0805 milligram per A-hr as determined from a least square fit of the data. When the emission rate and factors were compared with the ventilation measurements, this indicated that the ventilation hoods were operating at an efficiency of greater than 99%. The authors conclude that determining emission rates in this manner provides a more systematic basis for evaluating emission control in the workplace.","Workplace Emission Factors for Hexavalent Chromium Plating Abs: A methodology for determining workroom hexavalent-chromium (18540299) (Cr+6) emissions during chromium plating processes was described. The approach was based on collecting area particulate samples at various distances from a Cr+6 emission source along with measurements of the ventilation rate. The samples were analyzed for Cr+6 by proton induced X-ray emission spectroscopy. These data were transformed to emission rates and factors using a multipoint diffusion mass balance model in conjunction with variables that were specific to the geometry and patterns of work in the workspace. The method was applied to determining Cr+6 emission rates and factors in an electroplating shop where aluminum pistons were plated with chromium (7440473). Hourly Cr+6 emissions measured 49.6, 137, and 249 inches from the piston line varied from 1.09 to 8.59, 0.35 to 4.71, and 0.20 to 3.32 micrograms per cubic meter (microg/m3), respectively. All were below the American Conference of Governmental Industrial Hygienists Cr+6 standard of 50microg/m3. Baseline Cr+6 emissions averaged around 0.04 to 0.31microg/m3. Total chromium emissions were significantly related to the ampere hours (A-hr) of chromium plating. This yielded a Cr+6 emission factor of 0.0805 milligram per A-hr as determined from a least square fit of the data. When the emission rate and factors were compared with the ventilation measurements, this indicated that the ventilation hoods were operating at an efficiency of greater than 99%. The authors conclude that determining emission rates in this manner provides a more systematic basis for evaluating emission control in the workplace."
1514392,Collins et al. 1988,Column chromatographic speciation of chromium for chromium-vi and several species of chromium-iii,Biosis copyright: biol abs. rrm toxicity ion exchange chromatography,Column chromatographic speciation of chromium for chromium-vi and several species of chromium-iii Abs: Biosis copyright: biol abs. rrm toxicity ion exchange chromatography
1514391,Cohen and  Costa 1992,Chromium Compounds,"Chromium (7440473) compounds and their health effects were reviewed. Industrial applications of chromium and its compounds were described. Emissions from the metallurgical industry are the major sources of environmental contamination by chromium. Airborne chromium concentrations range from 0.2 to 1 nanogram per cubic meter (ng/m3) in remote rural areas to 13 to 30ng/m3 in urban areas. In chromium using industries, workplace chromium exposures typically range from 10 to 15 micrograms per cubic meter (microg/m3) in tanneries to 1,220microg/m3 in steel mills. The primary route of chromium absorption is by way of the respiratory tract. Health effects associated with chromium exposure were discussed. Chromium exists primarily as trivalent chromium (Cr+3) and hexavalent chromium (Cr+6). Cr+3 compounds have a relatively low order of toxicity relative to Cr+6 compounds. Acute inhalation of Cr+6 compounds can cause irritation or ulceration of the nasal mucosa and possible septal perforation. Cr+6 also causes gastrointestinal distress and olfactory sense impairment. Both Cr+6 and Cr+3 can cause contact dermatitis. The most serious health effects associated with chromium result from chronic exposure to Cr+6 compounds. These effects include gingivitis, chronic bronchitis, pneumonitis, liver and kidney damage, and lung and gastrointestinal tract cancer. Laboratory animal and epidemiological studies have confirmed direct links between Cr+6 exposure and cancer of various sites in the respiratory and gastrointestinal tracts. The review included discussions of chromium transport, distribution, and excretion, cellular uptake and metabolism, interactions with nucleic acids, induction of chromosome and chromatin damage, and induction of mutations.","Chromium Compounds Abs: Chromium (7440473) compounds and their health effects were reviewed. Industrial applications of chromium and its compounds were described. Emissions from the metallurgical industry are the major sources of environmental contamination by chromium. Airborne chromium concentrations range from 0.2 to 1 nanogram per cubic meter (ng/m3) in remote rural areas to 13 to 30ng/m3 in urban areas. In chromium using industries, workplace chromium exposures typically range from 10 to 15 micrograms per cubic meter (microg/m3) in tanneries to 1,220microg/m3 in steel mills. The primary route of chromium absorption is by way of the respiratory tract. Health effects associated with chromium exposure were discussed. Chromium exists primarily as trivalent chromium (Cr+3) and hexavalent chromium (Cr+6). Cr+3 compounds have a relatively low order of toxicity relative to Cr+6 compounds. Acute inhalation of Cr+6 compounds can cause irritation or ulceration of the nasal mucosa and possible septal perforation. Cr+6 also causes gastrointestinal distress and olfactory sense impairment. Both Cr+6 and Cr+3 can cause contact dermatitis. The most serious health effects associated with chromium result from chronic exposure to Cr+6 compounds. These effects include gingivitis, chronic bronchitis, pneumonitis, liver and kidney damage, and lung and gastrointestinal tract cancer. Laboratory animal and epidemiological studies have confirmed direct links between Cr+6 exposure and cancer of various sites in the respiratory and gastrointestinal tracts. The review included discussions of chromium transport, distribution, and excretion, cellular uptake and metabolism, interactions with nucleic acids, induction of chromosome and chromatin damage, and induction of mutations."
1514390,Clifford et al. 1986,Removing dissolved inorganic contaminants from water,Biosis copyright: biol abs. rrm coagulation flocculation ion exchange activated alumina reverse osmosis electrodialysis wastewater treatment industrial waste metals economics,Removing dissolved inorganic contaminants from water Abs: Biosis copyright: biol abs. rrm coagulation flocculation ion exchange activated alumina reverse osmosis electrodialysis wastewater treatment industrial waste metals economics
1514389,Cifuentes et al. 1996,Chromium sorption and reduction in soil with implications to bioremediation,"BIOSIS COPYRIGHT: BIOL ABS. Chromium must be removed or made immobile to reduce its toxicity in contaminated soil. The objectives of this study were (i) to compare Cr (III) and Cr (VI) sorption in three soils, (ii) to determine the potential of Cr-tolerant microorganisms to sorb Cr (III and VI) or to reduce Cr (VI) to Cr (III), and (iii) to determine the effect of organic amendment on stimulating Cr (VI) reduction by soil microorganisms. Sorption of Cr (III) was soil-dependent; the maximum sorbed was 431 mmol kg-1 in a clay loam soil. Sorption of Cr (VI) was concentration-dependent and independent of soil type. Maximum Cr (VI) sorbed was 63 mmol kg-1 soil. Aspergillus niger cells sorbed more Cr (VI) than Cr (III). Binding of Cr (III) by A. niger depended on pH and was greatest at pH 9, but binding of Cr (VI) was not pH-dependent. Soil amendment with freeze-dried A. niger increased sorption of Cr (III) significantly. Organic amendment of Cr (VI) contaminated soil resulted in both direct sorption of","Chromium sorption and reduction in soil with implications to bioremediation Abs: BIOSIS COPYRIGHT: BIOL ABS. Chromium must be removed or made immobile to reduce its toxicity in contaminated soil. The objectives of this study were (i) to compare Cr (III) and Cr (VI) sorption in three soils, (ii) to determine the potential of Cr-tolerant microorganisms to sorb Cr (III and VI) or to reduce Cr (VI) to Cr (III), and (iii) to determine the effect of organic amendment on stimulating Cr (VI) reduction by soil microorganisms. Sorption of Cr (III) was soil-dependent; the maximum sorbed was 431 mmol kg-1 in a clay loam soil. Sorption of Cr (VI) was concentration-dependent and independent of soil type. Maximum Cr (VI) sorbed was 63 mmol kg-1 soil. Aspergillus niger cells sorbed more Cr (VI) than Cr (III). Binding of Cr (III) by A. niger depended on pH and was greatest at pH 9, but binding of Cr (VI) was not pH-dependent. Soil amendment with freeze-dried A. niger increased sorption of Cr (III) significantly. Organic amendment of Cr (VI) contaminated soil resulted in both direct sorption of"
1514388,Cieslak-Golonka et al. 1999,"Electronic and infrared spectra of chromium(III) complexes isolated from the bioinorganic system: (Cr(VI)-ascorbic acid): Cr(VI) equal K2Cr2O7, KCrO3Cl, CrO2Cl2","BIOSIS COPYRIGHT: BIOL ABS. Six novel Cr(III) complexes obtained from the redox system (Cr(VI-H2asc) have been isolated and physicochemically characterized. The stoichiometries of the species were found to be dependent on both the initial Cr(VI) compound and the solvent. Spectrospcopic evidence suggested that the binding of the L-ascorbic acid to the chromium(III) ion is through oxygen C(3)-O, C(1)-O and C(2)-O, C(1)-O atoms. The coordination sphere of Cr(III) has been described assuming tetragonal deformation of the octahedral symmetry resulting from the presence of the oxygen atoms in various ligands and/or different positions of oxygen atoms in the H2asc molecule. Comparison with our results obtained earlier suggests the stronger covalency of the Cr-O bond found in the complexes studied in this work.","Electronic and infrared spectra of chromium(III) complexes isolated from the bioinorganic system: (Cr(VI)-ascorbic acid): Cr(VI) equal K2Cr2O7, KCrO3Cl, CrO2Cl2 Abs: BIOSIS COPYRIGHT: BIOL ABS. Six novel Cr(III) complexes obtained from the redox system (Cr(VI-H2asc) have been isolated and physicochemically characterized. The stoichiometries of the species were found to be dependent on both the initial Cr(VI) compound and the solvent. Spectrospcopic evidence suggested that the binding of the L-ascorbic acid to the chromium(III) ion is through oxygen C(3)-O, C(1)-O and C(2)-O, C(1)-O atoms. The coordination sphere of Cr(III) has been described assuming tetragonal deformation of the octahedral symmetry resulting from the presence of the oxygen atoms in various ligands and/or different positions of oxygen atoms in the H2asc molecule. Comparison with our results obtained earlier suggests the stronger covalency of the Cr-O bond found in the complexes studied in this work."
1514387,Chung et al. 1980,Toxicity of chromium and its interaction with copper and silver in chicks. AU - KANG MH,"HEEP COPYRIGHT: BIOL ABS. Toxicity of Cr and its interaction with other elements was studied during 3 experiments with 720 broiler chicks and 480 laying chicks for 16 wk. Chicks showed no adverse effect from 200 ppm Cr6+, but exhibited growth depression and mortality from 400 and 600 ppm. Chicks showed no adverse effect from 500 ppm Cr3+ but exhibited growth depression from 1500, 2500 and 4000 ppm. Chicks did not show any mortality from 1500, 2500 and 4000 ppm. There was no antagonistic interaction between Cr and Ag. Ag exaggerated the toxicity of Cr6+. Growth depression with Cr3+ was reduced by adding Cu. As higher levels of Cr6+ were administered, (200, 400 or 600 ppm) the accumulation of Cr in internal organs increased. Adding Ag did not influence the accumulation of Cr in internal organs increased. Adding Ag did not influence the accumulation of Cr in internal organs. As higher levels of Cr3+ were administered (500, 1500, 2500 or 4000 ppm) the accumulation of Cr in the internal organs increased. Adding Cu showed a tendency of reducing the accumulation of Cr in internal organs but was an insignificant difference. As the level of Cr3+ and Cr6+ became higher, feed efficiency increased. Adding Ag and Cu did not modify feed efficiency.","Toxicity of chromium and its interaction with copper and silver in chicks. AU - KANG MH Abs: HEEP COPYRIGHT: BIOL ABS. Toxicity of Cr and its interaction with other elements was studied during 3 experiments with 720 broiler chicks and 480 laying chicks for 16 wk. Chicks showed no adverse effect from 200 ppm Cr6+, but exhibited growth depression and mortality from 400 and 600 ppm. Chicks showed no adverse effect from 500 ppm Cr3+ but exhibited growth depression from 1500, 2500 and 4000 ppm. Chicks did not show any mortality from 1500, 2500 and 4000 ppm. There was no antagonistic interaction between Cr and Ag. Ag exaggerated the toxicity of Cr6+. Growth depression with Cr3+ was reduced by adding Cu. As higher levels of Cr6+ were administered, (200, 400 or 600 ppm) the accumulation of Cr in internal organs increased. Adding Ag did not influence the accumulation of Cr in internal organs increased. Adding Ag did not influence the accumulation of Cr in internal organs. As higher levels of Cr3+ were administered (500, 1500, 2500 or 4000 ppm) the accumulation of Cr in the internal organs increased. Adding Cu showed a tendency of reducing the accumulation of Cr in internal organs but was an insignificant difference. As the level of Cr3+ and Cr6+ became higher, feed efficiency increased. Adding Ag and Cu did not modify feed efficiency."
1514386,Chuan and  Liu 1996,Release behavior of chromium from tannery sludge,"BIOSIS COPYRIGHT: BIOL ABS. The release behavior of chromium from tannery sludge was assessed in this study. Fundamental properties of sludge were characterized. Total Cr content was 17,200 mg/kg. Trivalent chromium, Cr(III), was the predominant species in the sludge. The total Cr and Cr(VI) concentrations in the leachate of TCLP were 5.02 and 0.25 mg/dm3, respectively. Solubility of Cr from sludge was the lowest in the neutral range. Both pH and redox potential significantly affected release of Cr from the sludge. When sludge suspension was continuously aerated with oxygen for 600 hours, pH increased from 7.1 to 7.3, and redox potential increased from -300 to 295 mV, respectively. Dissolved Cr concentrations were lower than 7 mg/kg during the aeration period. The equilibrium solubility experiments were first conducted when the pH value was maintained at 4.2, and varied redox potential (0, 150, 250, 320, 470 mV), dissolved Cr concentrations decreased with increased redox potential. When the pH val","Release behavior of chromium from tannery sludge Abs: BIOSIS COPYRIGHT: BIOL ABS. The release behavior of chromium from tannery sludge was assessed in this study. Fundamental properties of sludge were characterized. Total Cr content was 17,200 mg/kg. Trivalent chromium, Cr(III), was the predominant species in the sludge. The total Cr and Cr(VI) concentrations in the leachate of TCLP were 5.02 and 0.25 mg/dm3, respectively. Solubility of Cr from sludge was the lowest in the neutral range. Both pH and redox potential significantly affected release of Cr from the sludge. When sludge suspension was continuously aerated with oxygen for 600 hours, pH increased from 7.1 to 7.3, and redox potential increased from -300 to 295 mV, respectively. Dissolved Cr concentrations were lower than 7 mg/kg during the aeration period. The equilibrium solubility experiments were first conducted when the pH value was maintained at 4.2, and varied redox potential (0, 150, 250, 320, 470 mV), dissolved Cr concentrations decreased with increased redox potential. When the pH val"
1514385,Christensen et al. 1999,Certification of Cr(VI) and total leachable Cr contents in welding dust loaded on a filter (CRM 545),"BIOSIS COPYRIGHT: BIOL ABS. In order to improve and control the quality of measurement of Cor(VI) and leachable Cr in welding dust loaded on a filter, the Standards, Measurements and Testing Programme (formerly BCR) of the European Commission has carried out a project, of which the final aim was to certify a reference material. This paper describes the preparation of a batch of 1100 filters loaded with welding dust, containing approximately 100 mug Cr(VI) per mg dust, which is as normally encountered on the personal filter monitors of stainless steel welders. The homogeneity and stability studies and the analytical work performed for the certification of the contents of Cr(VI) and the total leachable Cr content are also described, as well as the methods used to certify the mass fraction of Cr(VI) (40.16 | 0.60 g9.47 | 1.30 g kg-1 on a dry matter basis). A brief description of the preliminary feasibility study is also given.","Certification of Cr(VI) and total leachable Cr contents in welding dust loaded on a filter (CRM 545) Abs: BIOSIS COPYRIGHT: BIOL ABS. In order to improve and control the quality of measurement of Cor(VI) and leachable Cr in welding dust loaded on a filter, the Standards, Measurements and Testing Programme (formerly BCR) of the European Commission has carried out a project, of which the final aim was to certify a reference material. This paper describes the preparation of a batch of 1100 filters loaded with welding dust, containing approximately 100 mug Cr(VI) per mg dust, which is as normally encountered on the personal filter monitors of stainless steel welders. The homogeneity and stability studies and the analytical work performed for the certification of the contents of Cr(VI) and the total leachable Cr content are also described, as well as the methods used to certify the mass fraction of Cr(VI) (40.16 | 0.60 g9.47 | 1.30 g kg-1 on a dry matter basis). A brief description of the preliminary feasibility study is also given."
1514384,Choi et al. 1981,The influences of cobalt on chromium (VI) toxicity in chicks,"HEEP COPYRIGHT: BIOL ABS. An experiment was conducted with 480 chicks for 5 wk to study the toxicity of dietary Cr6+ and the influences of Co on the Cr toxicity. Levels of added Cr (0, 300, 600 and 900 ppm) were added in the absence or presence of the same level of 150 ppm Co. Three pens of 20 chicks were assigned to each dietary treatment; P < 0.05 was considered the limit of statistical significance. Chicks showed adverse effect from 300 ppm Cr6+ in growth rate but from 600 ppm in mortality. Co exaggerated Cr toxicity effects on growth rate and mortality. As higher levels of Cr6+ were administered, an increased feed requirement was shown. Adding Co increased the feed requirement at the level of 600 ppm Cr6+ but did not modify the feed requirement at the other levels of Cr6+.","The influences of cobalt on chromium (VI) toxicity in chicks Abs: HEEP COPYRIGHT: BIOL ABS. An experiment was conducted with 480 chicks for 5 wk to study the toxicity of dietary Cr6+ and the influences of Co on the Cr toxicity. Levels of added Cr (0, 300, 600 and 900 ppm) were added in the absence or presence of the same level of 150 ppm Co. Three pens of 20 chicks were assigned to each dietary treatment; P < 0.05 was considered the limit of statistical significance. Chicks showed adverse effect from 300 ppm Cr6+ in growth rate but from 600 ppm in mortality. Co exaggerated Cr toxicity effects on growth rate and mortality. As higher levels of Cr6+ were administered, an increased feed requirement was shown. Adding Co increased the feed requirement at the level of 600 ppm Cr6+ but did not modify the feed requirement at the other levels of Cr6+."
1514383,Choi and  Young 1996,Factors affecting bioremediation of chromiumvi-contaminated soils,Biosis copyright: biol abs. rrm meeting abstract heavy metal toxicity pollution biodegradation industrial waste,Factors affecting bioremediation of chromiumvi-contaminated soils Abs: Biosis copyright: biol abs. rrm meeting abstract heavy metal toxicity pollution biodegradation industrial waste
1514382,Choi and  Young 1995,A comparison between bacterial crvi resistance and crvi reduction among environmental isolates,Biosis copyright: biol abs. rrm meeting abstract chromium soil contamination glucose,A comparison between bacterial crvi resistance and crvi reduction among environmental isolates Abs: Biosis copyright: biol abs. rrm meeting abstract chromium soil contamination glucose
1514380,Barthelemy et al. 1975,A case of pancreatitis during a lead colic crisis,Heep copyright: biol abs. human factory exposure hypo chromic anemia delta amino levulinic-acid abdominal pain diagnosis amylasemia amylasuria lipasemia duodenal fluid,A case of pancreatitis during a lead colic crisis Abs: Heep copyright: biol abs. human factory exposure hypo chromic anemia delta amino levulinic-acid abdominal pain diagnosis amylasemia amylasuria lipasemia duodenal fluid
1514379,Barron and  Adelman 1984,"Nucleic acid, protein content and growth of larval fish sublethally exposed to various toxicants","HEEP COPYRIGHT: BIOL ABS. Larval fathead minnows (Pimephales pomelas) were exposed for 96 h to several concentrations of benzophenone, ethyl acetate, Cr (VI), HCN or p-cresol. The range of safe concentrations determined from 96 h macromolecular content (RNA, DNA and protein) and growth was within or near the range of safe concentrations determined by concomitant longer term exposure (28-32 day early life stage toxicity test). RNA, DNA and protein content/larva and RNA ratio were sensitive to toxicant stress and followed a log-linear dose response. Larval RNA content appeared to be the 96 h measurement most responsive to toxicant exposure. A disruption of nucleic acid and protein metabolism apparently occurred within 96 h of sublethal toxicant exposure and resulted in decreased rates of mitosis, reduced protein synthesis and reduced growth. Measurement of growth and macromolecular content after a 96 h larval exposure provided a physiologically relevant measurement of toxicity that was predictive of longer term sublethal toxicity.","Nucleic acid, protein content and growth of larval fish sublethally exposed to various toxicants Abs: HEEP COPYRIGHT: BIOL ABS. Larval fathead minnows (Pimephales pomelas) were exposed for 96 h to several concentrations of benzophenone, ethyl acetate, Cr (VI), HCN or p-cresol. The range of safe concentrations determined from 96 h macromolecular content (RNA, DNA and protein) and growth was within or near the range of safe concentrations determined by concomitant longer term exposure (28-32 day early life stage toxicity test). RNA, DNA and protein content/larva and RNA ratio were sensitive to toxicant stress and followed a log-linear dose response. Larval RNA content appeared to be the 96 h measurement most responsive to toxicant exposure. A disruption of nucleic acid and protein metabolism apparently occurred within 96 h of sublethal toxicant exposure and resulted in decreased rates of mitosis, reduced protein synthesis and reduced growth. Measurement of growth and macromolecular content after a 96 h larval exposure provided a physiologically relevant measurement of toxicity that was predictive of longer term sublethal toxicity."
1514378,Barisci and  Wallace 1995,Development of an improved on-line chromatographic monitor with new methods for environmental and process control,Biosis copyright: biol abs. rrm research article analytical method automation environmental toxicology cyanides chloramines chromium copper lead aluminum,Development of an improved on-line chromatographic monitor with new methods for environmental and process control Abs: Biosis copyright: biol abs. rrm research article analytical method automation environmental toxicology cyanides chloramines chromium copper lead aluminum
1514377,Barcelo et al. 1986,Water relations of chromium-vi treated bush bean plants phaseolus-vulgaris cultivar contender under both normal and water stress conditions,Biosis copyright: biol abs. rrm phytotoxicity leaf water potential cell wall elasticity,Water relations of chromium-vi treated bush bean plants phaseolus-vulgaris cultivar contender under both normal and water stress conditions Abs: Biosis copyright: biol abs. rrm phytotoxicity leaf water potential cell wall elasticity
1514376,Balasubramanian and  Maheswari 1996,Indirect spectrophotometric determination of chromium,"BIOSIS COPYRIGHT: BIOL ABS. A sensitive spectrophotometric method for determining trace amounts of chromium(VI) is described. In the presence of acetate buffer, chromium(VI) oxidizes hydroxylamine quantitatively to nitrite at pH 4.0 | 0.5. The nitrite diazotizes p-nitroaniline to form a diazonium salt that, in acidic medium, couples with N-(1-naphthyl)ethylenediamine dihydrochloride to form an azo dye with a molar absorptivity of 4.1 104 L/mol-cm at 545 nm. The color is stable for 5 h, and the system obeys Beer's law in the range 0-8 mug chromium(VI) in a final volume of 10 mL. The detection limit of chromium(VI) is 0.6 mug. Chromium(III) can be determined after it is oxidized with bromine water in alkaline medium to chromium(VI). Extraction of the azo dye in alkaline medium with methyl isobutyl ketone followed by addition of methanolic hydrochloric acid permitted determination of chromium(VI) down to 10 ng/mL. The method has been used to determine chromium in alloy steels, pharmaceutical prepar","Indirect spectrophotometric determination of chromium Abs: BIOSIS COPYRIGHT: BIOL ABS. A sensitive spectrophotometric method for determining trace amounts of chromium(VI) is described. In the presence of acetate buffer, chromium(VI) oxidizes hydroxylamine quantitatively to nitrite at pH 4.0 | 0.5. The nitrite diazotizes p-nitroaniline to form a diazonium salt that, in acidic medium, couples with N-(1-naphthyl)ethylenediamine dihydrochloride to form an azo dye with a molar absorptivity of 4.1 104 L/mol-cm at 545 nm. The color is stable for 5 h, and the system obeys Beer's law in the range 0-8 mug chromium(VI) in a final volume of 10 mL. The detection limit of chromium(VI) is 0.6 mug. Chromium(III) can be determined after it is oxidized with bromine water in alkaline medium to chromium(VI). Extraction of the azo dye in alkaline medium with methyl isobutyl ketone followed by addition of methanolic hydrochloric acid permitted determination of chromium(VI) down to 10 ng/mL. The method has been used to determine chromium in alloy steels, pharmaceutical prepar"
1514375,Balakin et al. 1981,Synthesis and study of the effect of oligomeric quaternary salts on the excretion and resorption of hexavalent chromium from the rat organism,,Synthesis and study of the effect of oligomeric quaternary salts on the excretion and resorption of hexavalent chromium from the rat organism Abs: 
1514373,Bailey et al. 1992,Sorption onto and recovery of chromium-vi using iron-oxide-coated sand,Biosis copyright: biol abs. rrm wastewater treatment water pollution control metals recovery kinetics efficiency,Sorption onto and recovery of chromium-vi using iron-oxide-coated sand Abs: Biosis copyright: biol abs. rrm wastewater treatment water pollution control metals recovery kinetics efficiency
1514371,Bader et al. 1998,Aerobic reduction of hexavalent chromium by indigenous soil microbial populations,Biosis copyright: biol abs. rrm meeting abstract meeting poster bacteria indigenous soil microbial population chromium vi ion soil contaminant reduction toxicity chromium iii ion chromate soil science bacteriology metabolism soil,Aerobic reduction of hexavalent chromium by indigenous soil microbial populations Abs: Biosis copyright: biol abs. rrm meeting abstract meeting poster bacteria indigenous soil microbial population chromium vi ion soil contaminant reduction toxicity chromium iii ion chromate soil science bacteriology metabolism soil
1514370,Bader et al. 1999,Chromium-resistant bacterial populations from a site heavily contaminated with hexavalent chromium,"BIOSIS COPYRIGHT: BIOL ABS. Chromium-containing industrial effluents are primarily responsible for environmental contamination by toxic and highly mobile, hexavalent chromium. The dilution plate-count method, using media amended with Cr(VI) at concentrations ranging from 0 to 1000 mg L-1, was used to compare the sizes of Cr(VI)-resistant bacterial populations from a soil contaminated with 25 100 mg kg-1 total Cr (12400 mg kg-1 Cr(VI)) to those isolated from a slightly contaminated soil (99.6 mg kg-1 total Cr) and two other soils without any history of Cr contamination. Bacterial populations resistant to 500 mg L-1 Cr(VI) were isolated from all soils except the heavily contaminated soil. To determine whether Cr-resistant bacterial populations were indigenous to both the contaminated and the uncontaminated soils, enrichment cultures containing Cr(VI) at concentrations ranging from 0 to 1000 mg L-1 were employed. Bacterial populations, as high as 105 (colony forming units) CFU g-1 soil, tolerant of","Chromium-resistant bacterial populations from a site heavily contaminated with hexavalent chromium Abs: BIOSIS COPYRIGHT: BIOL ABS. Chromium-containing industrial effluents are primarily responsible for environmental contamination by toxic and highly mobile, hexavalent chromium. The dilution plate-count method, using media amended with Cr(VI) at concentrations ranging from 0 to 1000 mg L-1, was used to compare the sizes of Cr(VI)-resistant bacterial populations from a soil contaminated with 25 100 mg kg-1 total Cr (12400 mg kg-1 Cr(VI)) to those isolated from a slightly contaminated soil (99.6 mg kg-1 total Cr) and two other soils without any history of Cr contamination. Bacterial populations resistant to 500 mg L-1 Cr(VI) were isolated from all soils except the heavily contaminated soil. To determine whether Cr-resistant bacterial populations were indigenous to both the contaminated and the uncontaminated soils, enrichment cultures containing Cr(VI) at concentrations ranging from 0 to 1000 mg L-1 were employed. Bacterial populations, as high as 105 (colony forming units) CFU g-1 soil, tolerant of"
1514369,Azizian et al. 1997,Development characterization and performance evaluation of ferrous-ferric oxide adsorbents for metal removal from contaminated groundwater,Biosis copyright: biol abs. rrm meeting abstract ferrous-ferric oxide adsorbents groundwater contamination magnetite-coated sand leadii chromiumvi ironiii hydroxoacetate chromate removal reduction capacity pollution,Development characterization and performance evaluation of ferrous-ferric oxide adsorbents for metal removal from contaminated groundwater Abs: Biosis copyright: biol abs. rrm meeting abstract ferrous-ferric oxide adsorbents groundwater contamination magnetite-coated sand leadii chromiumvi ironiii hydroxoacetate chromate removal reduction capacity pollution
1514362,Chirwa and  Wang 1997,Hexavalent chromium reduction by Bacillus sp. in a packed-bed bioreactor,"BIOSIS COPYRIGHT: BIOL ABS. The potential for fixed-film bioreactors to reduce Cr(VI) was demonstrated using a Cr(VI)-reducing species, Bacillus sp. A bench-scale, packed-bed bioreactor was operated to steady-state conditions under a range of influent Cr(VI) concentrations (10-200 mg) and hydraulic detention times (6-24 h, clean bed) with near complete removal of Cr(VI). The steady-state Cr(VI) reduction efficiency was not affected by the influent Cr(VI) concentration or hydraulic detention time. Chromium mass balance analysis revealed that nearly all the Cr(VI) fed to the bioreactor was accounted for in the effluent as Cr(VI) and Cr(III). Total cell mass in the bioreactor decreased with increasing Cr(VI) loading rate, but it stabilized after a loading limit was reached (1016 mg of Cr(VI)/L day) when operated under 24 h hydraulic detention time. The bioreactor showed strong resilience by recovering from Cr(VI) overloading through reduction in influent Cr(VI) concentration.","Hexavalent chromium reduction by Bacillus sp. in a packed-bed bioreactor Abs: BIOSIS COPYRIGHT: BIOL ABS. The potential for fixed-film bioreactors to reduce Cr(VI) was demonstrated using a Cr(VI)-reducing species, Bacillus sp. A bench-scale, packed-bed bioreactor was operated to steady-state conditions under a range of influent Cr(VI) concentrations (10-200 mg) and hydraulic detention times (6-24 h, clean bed) with near complete removal of Cr(VI). The steady-state Cr(VI) reduction efficiency was not affected by the influent Cr(VI) concentration or hydraulic detention time. Chromium mass balance analysis revealed that nearly all the Cr(VI) fed to the bioreactor was accounted for in the effluent as Cr(VI) and Cr(III). Total cell mass in the bioreactor decreased with increasing Cr(VI) loading rate, but it stabilized after a loading limit was reached (1016 mg of Cr(VI)/L day) when operated under 24 h hydraulic detention time. The bioreactor showed strong resilience by recovering from Cr(VI) overloading through reduction in influent Cr(VI) concentration."
1514351,Chinthamreddy and  Reddy 1999,Oxidation and mobility of trivalent chromium in manganese-enriched clays during electrokinetic remediation,"BIOSIS COPYRIGHT: BIOL ABS. This article presents the results of an investigation that assessed the extent and effect of oxidation of Cr(III) in manganese-enriched clays on the electrokinetic remedial efficiency. Because chromium commonly exists along with nickel and cadmium at contaminated sites, the effects of changes in chromium redox chemistry on the migration of the coexisting nickel and cadmium was also studied. Bench-scale electrokinetic experiments were conducted using two different clays: kaolin, a typical low buf II) into Cr(VI) ranged from 67% in kaolin to 28% in glacial till even before the application of induced electric potential. The low extent of oxidation of Cr(III) in glacial till may be attributed to the initial precipitation of Cr(III) as Cr(OH)3 resulting from high soil pH, reducing aqueous Cr(III) concentrations present within the soil. In kaolin, Cr(III), Ni(II), and Cd(II) under electric potential migrated toward cathode and precipitated near the cathode due to high soil pH.","Oxidation and mobility of trivalent chromium in manganese-enriched clays during electrokinetic remediation Abs: BIOSIS COPYRIGHT: BIOL ABS. This article presents the results of an investigation that assessed the extent and effect of oxidation of Cr(III) in manganese-enriched clays on the electrokinetic remedial efficiency. Because chromium commonly exists along with nickel and cadmium at contaminated sites, the effects of changes in chromium redox chemistry on the migration of the coexisting nickel and cadmium was also studied. Bench-scale electrokinetic experiments were conducted using two different clays: kaolin, a typical low buf II) into Cr(VI) ranged from 67% in kaolin to 28% in glacial till even before the application of induced electric potential. The low extent of oxidation of Cr(III) in glacial till may be attributed to the initial precipitation of Cr(III) as Cr(OH)3 resulting from high soil pH, reducing aqueous Cr(III) concentrations present within the soil. In kaolin, Cr(III), Ni(II), and Cd(II) under electric potential migrated toward cathode and precipitated near the cathode due to high soil pH."
1514350,Chiarizia 1991,"Application of supported liquid membranes for removal of nitrate, technetium (VII) and chromium (VI) from groundwater","BIOSIS COPYRIGHT: BIOL ABS. The separation of nitrate, pertechnetate and chromate ions from synthetic Hanford site groundwater was studied by liquid-liquid extraction and by supported liquid membranes, SLMs. Three different commercially available long-chain aliphatic amines. Primene JM-T (primary), Amberlite LA-2 (secondary) and trilaurylamine (TLA, tertiary), were investigated as membrane carriers. n-Dodecane was used as diluent and polypropylene membranes were used as the support. Sodium hydroxide was used as the stripping agent. The basic strength of the three amines in dodecane was studied by biphasic potentiometric titrations using a glass electrode. Flat-sheet membrane experiments, where the removal of nitric acid from the feed solution was followed by using either a glass electrode or a nitrate electrode, showed that the secondary and primary amines are more effective than the tertiary one. A detailed study of the permeation of nitric acid through SLMs as a function of the concentration of t","Application of supported liquid membranes for removal of nitrate, technetium (VII) and chromium (VI) from groundwater Abs: BIOSIS COPYRIGHT: BIOL ABS. The separation of nitrate, pertechnetate and chromate ions from synthetic Hanford site groundwater was studied by liquid-liquid extraction and by supported liquid membranes, SLMs. Three different commercially available long-chain aliphatic amines. Primene JM-T (primary), Amberlite LA-2 (secondary) and trilaurylamine (TLA, tertiary), were investigated as membrane carriers. n-Dodecane was used as diluent and polypropylene membranes were used as the support. Sodium hydroxide was used as the stripping agent. The basic strength of the three amines in dodecane was studied by biphasic potentiometric titrations using a glass electrode. Flat-sheet membrane experiments, where the removal of nitric acid from the feed solution was followed by using either a glass electrode or a nitrate electrode, showed that the secondary and primary amines are more effective than the tertiary one. A detailed study of the permeation of nitric acid through SLMs as a function of the concentration of t"
1514349,Cheng et al. 1999,Industrial applications of rumen microbes: Review,"BIOSIS COPYRIGHT: BIOL ABS. The rumen microbial ecosystem is coming to be recognized as a rich alternative source of genes for industrially useful enzymes. Recent advances in biotechnology are enabling development of novel strategies for effective delivery and enhancement of these gene products. One particularly promising avenue for industrial application of rumen enzymes is as feed supplements for nonruminant and ruminant animal diets. Increasing competition in the livestock industry has forced producers to cut costs by adopting new technologies aimed at increasing production efficiency. Cellulases, xylanases, beta-glucanases, pectinases, and phytases have been shown to increase the efficiency of feedstuff utilization (e.g., degradation of cellulose, xylan and beta-glucan) and to decrease pollutants (e.g., phytic acid). These enzymes enhance the availability of feed components to the animal and eliminate some of their naturally occurring antinutritional effects. In the past, the cost and inconven","Industrial applications of rumen microbes: Review Abs: BIOSIS COPYRIGHT: BIOL ABS. The rumen microbial ecosystem is coming to be recognized as a rich alternative source of genes for industrially useful enzymes. Recent advances in biotechnology are enabling development of novel strategies for effective delivery and enhancement of these gene products. One particularly promising avenue for industrial application of rumen enzymes is as feed supplements for nonruminant and ruminant animal diets. Increasing competition in the livestock industry has forced producers to cut costs by adopting new technologies aimed at increasing production efficiency. Cellulases, xylanases, beta-glucanases, pectinases, and phytases have been shown to increase the efficiency of feedstuff utilization (e.g., degradation of cellulose, xylan and beta-glucan) and to decrease pollutants (e.g., phytic acid). These enzymes enhance the availability of feed components to the animal and eliminate some of their naturally occurring antinutritional effects. In the past, the cost and inconven"
1514348,Chen and  Hao 1998,Microbial chromium vi reduction,Biosis copyright: biol abs. rrm literature review hexavalent chromium microbial reduction pollutant bioprocess engineering waste management waste treatment chromate,Microbial chromium vi reduction Abs: Biosis copyright: biol abs. rrm literature review hexavalent chromium microbial reduction pollutant bioprocess engineering waste management waste treatment chromate
1514347,Chen and  Hao 1997,Biological removal of aqueous hexavalent chromium,"BIOSIS COPYRIGHT: BIOL ABS. The conventional chemical reduction of Cr(VI) to Cr(III) and subsequent Cr(OH)3 precipitation are expensive due to the use of large amounts of chemicals and the generation of chemical sludges. An attempt was carried out for microbial Cr(VI) removal in an anaerobic chemostat fed with an acetate-containing synthetic medium. With 26 mg Cr(VI) dm-3 in the influent, almost complete removal of Cr(VI) was achieved at dilution rates of 0.15 and 0.32 day-1 at 20êC and at 35êC, respectively. The optimum Cr(VI) mass loading and the specific Cr(VI) applied rates were found to be 5 mg Cr(VI) dm-3 day-1 and 0.02 mg Cr(VI) mg-1 VSS day-1, respectively. Either the influent Cr(VI) concentration or the dilution rate could be adjusted to maintain an efficient removal of Cr(VI) in a continuous operation. Since the Cr(VI)-reducing activity is associated with the biomass concentration in the system, recycling the effluent solids is essential for practical application. In a batch reactor wit","Biological removal of aqueous hexavalent chromium Abs: BIOSIS COPYRIGHT: BIOL ABS. The conventional chemical reduction of Cr(VI) to Cr(III) and subsequent Cr(OH)3 precipitation are expensive due to the use of large amounts of chemicals and the generation of chemical sludges. An attempt was carried out for microbial Cr(VI) removal in an anaerobic chemostat fed with an acetate-containing synthetic medium. With 26 mg Cr(VI) dm-3 in the influent, almost complete removal of Cr(VI) was achieved at dilution rates of 0.15 and 0.32 day-1 at 20êC and at 35êC, respectively. The optimum Cr(VI) mass loading and the specific Cr(VI) applied rates were found to be 5 mg Cr(VI) dm-3 day-1 and 0.02 mg Cr(VI) mg-1 VSS day-1, respectively. Either the influent Cr(VI) concentration or the dilution rate could be adjusted to maintain an efficient removal of Cr(VI) in a continuous operation. Since the Cr(VI)-reducing activity is associated with the biomass concentration in the system, recycling the effluent solids is essential for practical application. In a batch reactor wit"
1514346,Chen and  Hao 1996,Environmental factors and modeling in microbial chromium (VI) reduction,"BIOSIS COPYRIGHT: BIOL ABS. A Cr(VI)-reducing culture was enriched from an anaerobic chemostat fed with synthetic media containing acetate and Cr(VI). The enriched culture was used for a series of batch tests to investigate several environmental factors affecting microbial Cr(VI) reduction. Under carbon-limiting conditions, the extent of Cr(VI) reduction proportionally depended on the carbon concentration and no reduction of Cr(VI) was observed in the absence of acetate. Cr(VI) reduction was also dependent upon the initial biomass level and the type of organic compounds. The developed model predicted Cr(VI) reduction well at different Cr(VI) concentrations. Sulfate at 120 mg SO42- or nitrate at 150 mg N/L slightly inhibited Cr(VI) reduction. Reduction of nitrate but not sulfate was observed along with Cr(VI) reduction. Cr(VI) was not reduced by the aerobically growing culture, and it was found that oxygen inhibitory effects on Cr(VI) reduction were reversible. The optimum pH and temperature for C","Environmental factors and modeling in microbial chromium (VI) reduction Abs: BIOSIS COPYRIGHT: BIOL ABS. A Cr(VI)-reducing culture was enriched from an anaerobic chemostat fed with synthetic media containing acetate and Cr(VI). The enriched culture was used for a series of batch tests to investigate several environmental factors affecting microbial Cr(VI) reduction. Under carbon-limiting conditions, the extent of Cr(VI) reduction proportionally depended on the carbon concentration and no reduction of Cr(VI) was observed in the absence of acetate. Cr(VI) reduction was also dependent upon the initial biomass level and the type of organic compounds. The developed model predicted Cr(VI) reduction well at different Cr(VI) concentrations. Sulfate at 120 mg SO42- or nitrate at 150 mg N/L slightly inhibited Cr(VI) reduction. Reduction of nitrate but not sulfate was observed along with Cr(VI) reduction. Cr(VI) was not reduced by the aerobically growing culture, and it was found that oxygen inhibitory effects on Cr(VI) reduction were reversible. The optimum pH and temperature for C"
1514345,Chakraborty and  Mishra 1992,Speciation and determination of chromium in waters,"BIOSIS COPYRIGHT: BIOL ABS. Chromium is a metal which has both biological and environmental interest. It occurs in nature mostly in two stable oxidation states Cr(III) and Cr(VI). Cr(III) is non-toxic and plays a significant role in carbohydrate and fat metabolism, whereas Cr(VI) is highly toxic (MAC value 50 mug L-1 only). Being a major industrial pollutant, it has a hazardous effect on man, animal and plant life. In the present investigation, an attempt has been made to develop a highly selective and sensitive method for the spectrophotometric determination of Cr(III), Cr(VI) and total Cr in various water samples. Cr(VI) is extracted with N-hydroxy-N, N'-diphenylbenzamide in chloroform over 0.2-0.8 M HCl and for total Cr the sample is oxidised before extraction. The extracts are separately reacted with 1,5-diphenylcarbazide in strong hydrochloric acid media to give a red-violet coloured compound having a molar absorptivity of (9.10)etween the two gives the value for Cr(III) present in water sam","Speciation and determination of chromium in waters Abs: BIOSIS COPYRIGHT: BIOL ABS. Chromium is a metal which has both biological and environmental interest. It occurs in nature mostly in two stable oxidation states Cr(III) and Cr(VI). Cr(III) is non-toxic and plays a significant role in carbohydrate and fat metabolism, whereas Cr(VI) is highly toxic (MAC value 50 mug L-1 only). Being a major industrial pollutant, it has a hazardous effect on man, animal and plant life. In the present investigation, an attempt has been made to develop a highly selective and sensitive method for the spectrophotometric determination of Cr(III), Cr(VI) and total Cr in various water samples. Cr(VI) is extracted with N-hydroxy-N, N'-diphenylbenzamide in chloroform over 0.2-0.8 M HCl and for total Cr the sample is oxidised before extraction. The extracts are separately reacted with 1,5-diphenylcarbazide in strong hydrochloric acid media to give a red-violet coloured compound having a molar absorptivity of (9.10)etween the two gives the value for Cr(III) present in water sam"
1514344,Cespon-Romero et al. 1996,Preconcentration and speciation of chromium by the determination of total chromium and chromium(III) in natural waters by flame atomic absorption spectrometry with a chelating ion-exchange flow infection system,"BIOSIS COPYRIGHT: BIOL ABS. A simple method for the determination of chromium(III) and total chromium in a flow injection system comprising chelating ion-exchange and flame atomic absorption spectrometry (FAAS) was described. A minicolumn (85 mm6 mm i.d.) filled with a poly(aminophosphonic acid) chelating resin (PAPhA, 20-30 mesh) was used for speciation and preconcentration of chromium because this resin is selective for Cr(III) ions. The flow injection manifold employed allows a high rate of introduction of the sample and retention of Cr(III) on the minicolumn. Total chromium was obtained by an efficient reduction of Cr(VI) to Cr(III) by ascorbic acid as reducing reagent. Elution was performed by using a small volume of 0.5 M hydrochloric acid. For 6.6 ml samples, the detection limit for the total chromium and Cr(III) was 0.2 mug l-1. The precision (coefficient of variation) obtained for different amounts of Cr(III) and total Cr were 1.2-5.9% and 1.2-5.7%, respectively. Chemicals and flow variab","Preconcentration and speciation of chromium by the determination of total chromium and chromium(III) in natural waters by flame atomic absorption spectrometry with a chelating ion-exchange flow infection system Abs: BIOSIS COPYRIGHT: BIOL ABS. A simple method for the determination of chromium(III) and total chromium in a flow injection system comprising chelating ion-exchange and flame atomic absorption spectrometry (FAAS) was described. A minicolumn (85 mm6 mm i.d.) filled with a poly(aminophosphonic acid) chelating resin (PAPhA, 20-30 mesh) was used for speciation and preconcentration of chromium because this resin is selective for Cr(III) ions. The flow injection manifold employed allows a high rate of introduction of the sample and retention of Cr(III) on the minicolumn. Total chromium was obtained by an efficient reduction of Cr(VI) to Cr(III) by ascorbic acid as reducing reagent. Elution was performed by using a small volume of 0.5 M hydrochloric acid. For 6.6 ml samples, the detection limit for the total chromium and Cr(III) was 0.2 mug l-1. The precision (coefficient of variation) obtained for different amounts of Cr(III) and total Cr were 1.2-5.9% and 1.2-5.7%, respectively. Chemicals and flow variab"
1514343,Cervantes 1994,Heptavalent-chromium reduction by a chromate-resistant bacillus sp. strain au - campos j,Biosis copyright: biol abs. rrm meeting abstract bacillus trivalent chromium chromate reductase genetics metal metabolism,Heptavalent-chromium reduction by a chromate-resistant bacillus sp. strain au - campos j Abs: Biosis copyright: biol abs. rrm meeting abstract bacillus trivalent chromium chromate reductase genetics metal metabolism
1514342,Caron et al. 1991,Targeting of inducible gene expression by carcinogens in-vivo,Biosis copyright: biol abs. rrm abstract chick embryo liver chromium-vi mitomycin c 2 acetylaminofluorene aflatoxin b1 methanesulfonate nitrosamine genotoxicity beta actin gene transferrin albumin alanine synthase cytochrome pb1 p-450 dna damage,Targeting of inducible gene expression by carcinogens in-vivo Abs: Biosis copyright: biol abs. rrm abstract chick embryo liver chromium-vi mitomycin c 2 acetylaminofluorene aflatoxin b1 methanesulfonate nitrosamine genotoxicity beta actin gene transferrin albumin alanine synthase cytochrome pb1 p-450 dna damage
1514331,Cao and  Zhang 1999,Color reaction of chromium(VI) with p-amino-N.N-diethylaniline in the presence of ethanol and cyclohexyldiamine tetraacetic acid as well as its application in the species analysis of chromium,"BIOSIS COPYRIGHT: BIOL ABS. A simple, rapid and precise spectrophotometric method has been developed for the determination of chromium(III) and (VI). The reaction of Cr(VI) with p-amino-N.N-diethylaniline is almost complete in a short time and it yields a red product with a maximum absorption at 550 nm. Beer's law is obeyed in the Cr concentration range of 0 to 2000 mug dm-3. The molar absorptivity is 5.0of detection is 2.0 mug dm-3 and the relative standard deviation is 1.13 % for 5.04 mug C","Color reaction of chromium(VI) with p-amino-N.N-diethylaniline in the presence of ethanol and cyclohexyldiamine tetraacetic acid as well as its application in the species analysis of chromium Abs: BIOSIS COPYRIGHT: BIOL ABS. A simple, rapid and precise spectrophotometric method has been developed for the determination of chromium(III) and (VI). The reaction of Cr(VI) with p-amino-N.N-diethylaniline is almost complete in a short time and it yields a red product with a maximum absorption at 550 nm. Beer's law is obeyed in the Cr concentration range of 0 to 2000 mug dm-3. The molar absorptivity is 5.0of detection is 2.0 mug dm-3 and the relative standard deviation is 1.13 % for 5.04 mug C"
1514330,Campanella et al. 1993,Analytical problems in the definition of material balances in the incineration of urban sludge,BIOSIS COPYRIGHT: BIOL ABS. Different digestion methods for the determination of heavy metals in urban sludges and its ashes are investigated utilizing two reference materials. The reference sludge and a real urban sludge are then utilized for incineration experiments to evaluate environmental impact both of residual ashes and of fumes produced during incineration. Material balances are performed to evaluate the distribution of heavy metals during the incineration experiments.,Analytical problems in the definition of material balances in the incineration of urban sludge Abs: BIOSIS COPYRIGHT: BIOL ABS. Different digestion methods for the determination of heavy metals in urban sludges and its ashes are investigated utilizing two reference materials. The reference sludge and a real urban sludge are then utilized for incineration experiments to evaluate environmental impact both of residual ashes and of fumes produced during incineration. Material balances are performed to evaluate the distribution of heavy metals during the incineration experiments.
1514329,Calevro et al. 1998,"Tests of toxicity and teratogenicity in biphasic vertebrates treated with heavy metals (Cr3+, Al3+, Cd2+)","BIOSIS COPYRIGHT: BIOL ABS. Developmental toxicity of chromium(III), aluminium(III) and cadmium(II) were evaluated by examining abnormalities and mortality in embryos belonging to different species of amphibians. Cr(III) and AI(III) are lethal at 1.5 mM concentration, and seriously affect the differentiation of central nervous system, skeleton and eye, and cause cephalic and trunk oedemas at lower concentrations, being aluminium significantly more harmful than chromium. Cd(II), tested only in P. walti, is highly toxic: embryos exposed to concentrations ranging from 0.18 to 50 muM display malformations, delay and arrest of development in a dose dependent manner.","Tests of toxicity and teratogenicity in biphasic vertebrates treated with heavy metals (Cr3+, Al3+, Cd2+) Abs: BIOSIS COPYRIGHT: BIOL ABS. Developmental toxicity of chromium(III), aluminium(III) and cadmium(II) were evaluated by examining abnormalities and mortality in embryos belonging to different species of amphibians. Cr(III) and AI(III) are lethal at 1.5 mM concentration, and seriously affect the differentiation of central nervous system, skeleton and eye, and cause cephalic and trunk oedemas at lower concentrations, being aluminium significantly more harmful than chromium. Cd(II), tested only in P. walti, is highly toxic: embryos exposed to concentrations ranging from 0.18 to 50 muM display malformations, delay and arrest of development in a dose dependent manner."
1514328,Caldas et al. 1986,Contractility of granulation tissue to oxidizing agents and ferrochromium metal-fume components,,Contractility of granulation tissue to oxidizing agents and ferrochromium metal-fume components Abs: 
1514327,Calaminus and  Stahlberg 1998,Continuous in-line gasification/vitrification process for thermal waste treatment: Process technology and current status of projects,"BIOSIS COPYRIGHT: BIOL ABS. The Thermoselect High Temperature Recycling process has been developed in order to make available a thermal waste treatment technology avoiding major problems as known from traditional techniques like landfills or ashes, filter dust and emission producing processes. It combines slow degassing with fixed bed oxygen blown gasification and mineral and metal residue melting in a closed loop system. Municipal, industrial and other kinds of waste are compacted to less than one fifth of their originalcomponents such as metals and minerals are continuously fed into a high-temperature reactor (HTR). Pure oxygen is added in controlled quantities and reacts with the material following exothermic oxidisation reactions. Due to overall under-stoichiometric conditions, gasification products form a combustible synthesis gas. The heat of reaction leading to temperatures up to about 2000êC in the core of the lower HTR section acts to also smelt the metal and mineral emonstration plant in","Continuous in-line gasification/vitrification process for thermal waste treatment: Process technology and current status of projects Abs: BIOSIS COPYRIGHT: BIOL ABS. The Thermoselect High Temperature Recycling process has been developed in order to make available a thermal waste treatment technology avoiding major problems as known from traditional techniques like landfills or ashes, filter dust and emission producing processes. It combines slow degassing with fixed bed oxygen blown gasification and mineral and metal residue melting in a closed loop system. Municipal, industrial and other kinds of waste are compacted to less than one fifth of their originalcomponents such as metals and minerals are continuously fed into a high-temperature reactor (HTR). Pure oxygen is added in controlled quantities and reacts with the material following exothermic oxidisation reactions. Due to overall under-stoichiometric conditions, gasification products form a combustible synthesis gas. The heat of reaction leading to temperatures up to about 2000êC in the core of the lower HTR section acts to also smelt the metal and mineral emonstration plant in"
1514325,Byl et al. 1994,"Evaluation of peroxidase as a biochemical indicator of toxic chemical exposure in the aquatic plant Hydrilla verticillata, Royle","BIOSIS COPYRIGHT: BIOL ABS. Laboratory bioassays were conducted to determine the utility of peroxidase (POD) activity as a biochemical indicator of contaminant exposure in the aquatic plant Hydrilla verticillata, Royle. The plants were exposed to anthracene, sulfometuron methyl (Oust), Cd2+, Cr6+, CU2+,Mn2+, and Se4+ in concentration factors of 10. POD was extracted and measured by spectrophotometric assay. There was a significant increase in POD activity after a 5-d exposure to each of the chemicals at 1 mg. The optimum pH for POD activity after exposure to the chemicals was 5.5 to 6.0. The increase in POD was found to be dose dependent for each of the chemicals. The lowest concentration of chemical to induce a significant POD increase was 0.01 mg/L for anthracene, Oust, Cd, Cr, and Cu; 0.1 mg/L for Se; and 1.0 mg/L for Mn.","Evaluation of peroxidase as a biochemical indicator of toxic chemical exposure in the aquatic plant Hydrilla verticillata, Royle Abs: BIOSIS COPYRIGHT: BIOL ABS. Laboratory bioassays were conducted to determine the utility of peroxidase (POD) activity as a biochemical indicator of contaminant exposure in the aquatic plant Hydrilla verticillata, Royle. The plants were exposed to anthracene, sulfometuron methyl (Oust), Cd2+, Cr6+, CU2+,Mn2+, and Se4+ in concentration factors of 10. POD was extracted and measured by spectrophotometric assay. There was a significant increase in POD activity after a 5-d exposure to each of the chemicals at 1 mg. The optimum pH for POD activity after exposure to the chemicals was 5.5 to 6.0. The increase in POD was found to be dose dependent for each of the chemicals. The lowest concentration of chemical to induce a significant POD increase was 0.01 mg/L for anthracene, Oust, Cd, Cr, and Cu; 0.1 mg/L for Se; and 1.0 mg/L for Mn."
1514324,Bux and  Kasan 1996,Assessment of wastewater treatment sludges as metal biosorbents,"BIOSIS COPYRIGHT: BIOL ABS. The use of waste activated sludges as an efficient adsorbent for removal of heavy metals from industrial effluents has been considered as a viable alternative to chemical treatment methods. Waste activated sludge samples of fixed concentration from ten waste-water works were exposed to varying concentrations of solutions containing Cu2+, Cd2+, Cr3+, Cr6+, Ni2+ and Zn2+ under controlled laboratory conditions. All sludges exhibited potential for metal removal from solution, some displaying comparatively superior metal biosorption than others. In addition, certain sludges portrayed a preference for specific metal ions. There as an increase in quantity of metal ions biosorbed by all sludges, with increasing solution concentrations for all the metals, except Cr6+. The results produced an overall metal-ion preference by the sludges of Cu > Cd > Zn > Ni > Cr3+ > Cr6+ This study showed that waste activated sludges demonstrate potential as metal biosorbents.","Assessment of wastewater treatment sludges as metal biosorbents Abs: BIOSIS COPYRIGHT: BIOL ABS. The use of waste activated sludges as an efficient adsorbent for removal of heavy metals from industrial effluents has been considered as a viable alternative to chemical treatment methods. Waste activated sludge samples of fixed concentration from ten waste-water works were exposed to varying concentrations of solutions containing Cu2+, Cd2+, Cr3+, Cr6+, Ni2+ and Zn2+ under controlled laboratory conditions. All sludges exhibited potential for metal removal from solution, some displaying comparatively superior metal biosorption than others. In addition, certain sludges portrayed a preference for specific metal ions. There as an increase in quantity of metal ions biosorbed by all sludges, with increasing solution concentrations for all the metals, except Cr6+. The results produced an overall metal-ion preference by the sludges of Cu > Cd > Zn > Ni > Cr3+ > Cr6+ This study showed that waste activated sludges demonstrate potential as metal biosorbents."
1514323,Brun 1975,Statistical study of positive epidermal tests of 1000 cases of contact dermatitis,Heep copyright: biol abs.,Statistical study of positive epidermal tests of 1000 cases of contact dermatitis Abs: Heep copyright: biol abs.
1514322,Brown 1980,The use of Hydrobia jenkinsi to detect intermittent toxic discharges to a river,"PESTAB. River pollution in the Holme and its tributaries was monitoring during October 1975 to October 1977 using an in situ bioassay with the operculate gastropod Hydrobia jenkinsi. River samples artificially spiked with dieldrin or heavy metals were used in laboratory tests to assess survival rates of the gastropod in known concentrations of toxins. Close correlations were found between laboratory test responses and those recorded when H. jenkinsi was exposed to polluted river water samples. When caged H. jenkinsi were exposed in situ to water from pollutant discharge sites along the waterways, gastropod responses made it possible to detect when discharges were contaminated with certain heavy metals, especially copper and hexavalent chromium. In situ death was not attributed solely to dieldrin or heavy metals. At levels in excess of 30,000 ng/l, dieldrin failed to cause death of H. jenkinsi suggesting the need for an organism susceptible to pesticides as an indicator for river pollution by this organochlorine compound.","The use of Hydrobia jenkinsi to detect intermittent toxic discharges to a river Abs: PESTAB. River pollution in the Holme and its tributaries was monitoring during October 1975 to October 1977 using an in situ bioassay with the operculate gastropod Hydrobia jenkinsi. River samples artificially spiked with dieldrin or heavy metals were used in laboratory tests to assess survival rates of the gastropod in known concentrations of toxins. Close correlations were found between laboratory test responses and those recorded when H. jenkinsi was exposed to polluted river water samples. When caged H. jenkinsi were exposed in situ to water from pollutant discharge sites along the waterways, gastropod responses made it possible to detect when discharges were contaminated with certain heavy metals, especially copper and hexavalent chromium. In situ death was not attributed solely to dieldrin or heavy metals. At levels in excess of 30,000 ng/l, dieldrin failed to cause death of H. jenkinsi suggesting the need for an organism susceptible to pesticides as an indicator for river pollution by this organochlorine compound."
1514321,Brown et al. 1998,Kinetic analysis of multivalent metal reduction by metal-reducing bacteria au - gorby ya,Biosis copyright: biol abs. rrm meeting abstract meeting poster shewanella-alga shewanella-putrefaciens strain-bry metal-reducing bacteria strain-cn-32 lactate electron donor chromium vi ion reduction environmental contaminant electron acceptor cobalt ii ion ferric ion ferrous ion cobalt iii ion chromium iii ion technetium vii ion technetium iv ion pollution,Kinetic analysis of multivalent metal reduction by metal-reducing bacteria au - gorby ya Abs: Biosis copyright: biol abs. rrm meeting abstract meeting poster shewanella-alga shewanella-putrefaciens strain-bry metal-reducing bacteria strain-cn-32 lactate electron donor chromium vi ion reduction environmental contaminant electron acceptor cobalt ii ion ferric ion ferrous ion cobalt iii ion chromium iii ion technetium vii ion technetium iv ion pollution
1514320,Bronzetti et al. 1986,Mutagenicity of Complex Mixtures Used in Tannery,"A group of twenty eight commercial compounds used in a leather and tannery factory (SIC-3111) near Florence, Italy, were tested for mutagenic response following the procedures described by Ames. The S9 fraction of livers from mice pretreated with phenobarbital and beta-naphthoflavone was used as an activating system. The chemical composition was available for about five products, others were listed by commercial names. Eight products gave positive responses in one or more strains of Salmonella-typhimurium, and five responded positively in Saccharomyces-cervisiae (D7). Tanning agents Chromitan-B (CB) and Chromitan-MS (CMS) contained chromium(III) (16065831), but no chromium(VI) (18540299) was detected. CB was toxic to Salmonella (TA-98) and (TA-1537), and CMS was toxic to (TA-1537). Bruno-Avival (BA) and Rosso-Avival (RA) dyes were mutagenic to (TA-98) and (TA-1537), and Rosso-HR (RHR) induced histidine revertants in (TA-100) and (TA-98). CB, CMS, BA, RA, and RHR induced gene conversion and point mutation in (D7) of Saccharomyces. Silican and Blancotan-PRV showed weak genetic effects, but neither contained chromium(III). Erhavit-A, a product used in the liming process, gave positive results using (TA-1535), with or without metabolic activation. None of the two disinfectants and nine oil resins induced mutagenic response in Salmonella strains or (D7). The authors conclude that these results suggest that environmental health risks should be studied with complex mixtures as they occur in the environment.","Mutagenicity of Complex Mixtures Used in Tannery Abs: A group of twenty eight commercial compounds used in a leather and tannery factory (SIC-3111) near Florence, Italy, were tested for mutagenic response following the procedures described by Ames. The S9 fraction of livers from mice pretreated with phenobarbital and beta-naphthoflavone was used as an activating system. The chemical composition was available for about five products, others were listed by commercial names. Eight products gave positive responses in one or more strains of Salmonella-typhimurium, and five responded positively in Saccharomyces-cervisiae (D7). Tanning agents Chromitan-B (CB) and Chromitan-MS (CMS) contained chromium(III) (16065831), but no chromium(VI) (18540299) was detected. CB was toxic to Salmonella (TA-98) and (TA-1537), and CMS was toxic to (TA-1537). Bruno-Avival (BA) and Rosso-Avival (RA) dyes were mutagenic to (TA-98) and (TA-1537), and Rosso-HR (RHR) induced histidine revertants in (TA-100) and (TA-98). CB, CMS, BA, RA, and RHR induced gene conversion and point mutation in (D7) of Saccharomyces. Silican and Blancotan-PRV showed weak genetic effects, but neither contained chromium(III). Erhavit-A, a product used in the liming process, gave positive results using (TA-1535), with or without metabolic activation. None of the two disinfectants and nine oil resins induced mutagenic response in Salmonella strains or (D7). The authors conclude that these results suggest that environmental health risks should be studied with complex mixtures as they occur in the environment."
1514319,Broderius and  Smith 1979,"Lethal and sublethal effects of binary mixtures of cyanide and hexavalent chromium, zinc, or ammonia to the fathead minnow (Pimephales promelas) and rainbow trout (Salmo gairdneri)","HEEP COPYRIGHT: BIOL ABS. Various models are proposed predict the combined interactive effect on fish of mixtures of poisons from separate toxicities of individual substances. The success of these models was tested, using data describing the lethal and sublethal effects of individual substances or binary mixtures of HCN and Cr(VI), Zn(II) or NH2 to the fathead minnow (P. promelas) and rainbow trout (S. gairdneri). Using the strictly additive toxic unit and additive index approach, it was determined from log-dosage mortality curves that the Zn-HCN and ammonia-HCN mixtures were more acutely toxic and Cr-HCN less toxic than predicted. The concentration and response addition models, which were proposed for toxicants whose joint action was similar or independent, respectively, could not be used to predict dosage-mortality curves for the HCN mixtures. Linear regression lines representing the growth response of fish to log concentration for toxicants alone and in binary combinations were not significantly different. For the toxic substances tested, the sublethal joint action of individual toxicants was not predictable from existing models and, in most cases, no interaction was indicated. The interactive nature of toxicants may be a function of the concentrations tested causing different biological processes to be affected (e.g., mortality vs. growth) and different responses to be measured. A need still exists for development of a valid multiple toxicity approach for evaluating and predicting the toxicity of chemical combinations.","Lethal and sublethal effects of binary mixtures of cyanide and hexavalent chromium, zinc, or ammonia to the fathead minnow (Pimephales promelas) and rainbow trout (Salmo gairdneri) Abs: HEEP COPYRIGHT: BIOL ABS. Various models are proposed predict the combined interactive effect on fish of mixtures of poisons from separate toxicities of individual substances. The success of these models was tested, using data describing the lethal and sublethal effects of individual substances or binary mixtures of HCN and Cr(VI), Zn(II) or NH2 to the fathead minnow (P. promelas) and rainbow trout (S. gairdneri). Using the strictly additive toxic unit and additive index approach, it was determined from log-dosage mortality curves that the Zn-HCN and ammonia-HCN mixtures were more acutely toxic and Cr-HCN less toxic than predicted. The concentration and response addition models, which were proposed for toxicants whose joint action was similar or independent, respectively, could not be used to predict dosage-mortality curves for the HCN mixtures. Linear regression lines representing the growth response of fish to log concentration for toxicants alone and in binary combinations were not significantly different. For the toxic substances tested, the sublethal joint action of individual toxicants was not predictable from existing models and, in most cases, no interaction was indicated. The interactive nature of toxicants may be a function of the concentrations tested causing different biological processes to be affected (e.g., mortality vs. growth) and different responses to be measured. A need still exists for development of a valid multiple toxicity approach for evaluating and predicting the toxicity of chemical combinations."
1514318,Bristol et al. 1983,Lack Of Nephrotoxicity Of Dimethyl Sulfoxide In Man And Laboratory Animals AU - Bennett WM,"Nephrotoxic effects of dimethyl-sulfoxide (67685) (DMSO) were studied in humans and laboratory animals. Twenty one patients (17 males) and chronic stable neurologic deficits related to traumatic spinal cord injury were infused intravenously (iv) with 1 gram per kilogram (g/kg) DMSO for 10 minutes to 24 hours. Some patients were infused for 3 days. Parameters of kidney function such as blood urea nitrogen (BUN), serum creatinine, creatinine clearance, hemoglobin, myoglobin, urinary protein, glucose, and specific gravity were determined. No changes from baseline in BUN, serum, creatinine, and creatinine clearance were seen. Some hemoglobinuria was observed; no myoglobin was present. No increase in qualitative urine protein or glucose, nor decrease in first morning specific gravity was observed. Male Fischer-rats were given 40 percent DMSO iv for 15 minutes for 3 days. The animals were killed 72 hours later. Serum creatinine was determined and the kidneys were examined for histopathological changes. Acute renal failure was induced in rats by injecting 5 to 20 milligrams per kilogram potassium-dichromate. The animals were given 0 or 1g/kg DMSO intraperitoneally. They were killed 1 to 5 days later and serum creatinine was determined. In rats given DMSO iv over 3 days, no renal histopathological changes were seen. No significant changes in serum creatinine concentration occurred. No evidence of added nephrotoxicity, as indicated by changes in serum creatinine, was noted in rats with dichromate induced kidney failure given DMSO, compared with those given potassium-dichromate alone. The authors conclude that DMSO causes no short term nephrotoxic effect. DMSO given iv is safe to use in patients who are prospective renal transplant donors.","Lack Of Nephrotoxicity Of Dimethyl Sulfoxide In Man And Laboratory Animals AU - Bennett WM Abs: Nephrotoxic effects of dimethyl-sulfoxide (67685) (DMSO) were studied in humans and laboratory animals. Twenty one patients (17 males) and chronic stable neurologic deficits related to traumatic spinal cord injury were infused intravenously (iv) with 1 gram per kilogram (g/kg) DMSO for 10 minutes to 24 hours. Some patients were infused for 3 days. Parameters of kidney function such as blood urea nitrogen (BUN), serum creatinine, creatinine clearance, hemoglobin, myoglobin, urinary protein, glucose, and specific gravity were determined. No changes from baseline in BUN, serum, creatinine, and creatinine clearance were seen. Some hemoglobinuria was observed; no myoglobin was present. No increase in qualitative urine protein or glucose, nor decrease in first morning specific gravity was observed. Male Fischer-rats were given 40 percent DMSO iv for 15 minutes for 3 days. The animals were killed 72 hours later. Serum creatinine was determined and the kidneys were examined for histopathological changes. Acute renal failure was induced in rats by injecting 5 to 20 milligrams per kilogram potassium-dichromate. The animals were given 0 or 1g/kg DMSO intraperitoneally. They were killed 1 to 5 days later and serum creatinine was determined. In rats given DMSO iv over 3 days, no renal histopathological changes were seen. No significant changes in serum creatinine concentration occurred. No evidence of added nephrotoxicity, as indicated by changes in serum creatinine, was noted in rats with dichromate induced kidney failure given DMSO, compared with those given potassium-dichromate alone. The authors conclude that DMSO causes no short term nephrotoxic effect. DMSO given iv is safe to use in patients who are prospective renal transplant donors."
1514316,Bozzelli 1994,Removal of crvi from chromium contaminated sites by washing with hot water au - ososkov v,Biosis copyright: biol abs. rrm research article chromiumvi environmental toxin ore processing residue soil,Removal of crvi from chromium contaminated sites by washing with hot water au - ososkov v Abs: Biosis copyright: biol abs. rrm research article chromiumvi environmental toxin ore processing residue soil
1514315,Bowers et al. 1992,Interactions of hexavalent chromium with activated carbon,Biosis copyright: biol abs. rrm abstract wastewater treatment oxyanion removal,Interactions of hexavalent chromium with activated carbon Abs: Biosis copyright: biol abs. rrm abstract wastewater treatment oxyanion removal
1514314,Bouwer et al. 1988,Coping with groundwater contamination,Biosis copyright: biol abs. rrm review water pollution management water treatment monitoring,Coping with groundwater contamination Abs: Biosis copyright: biol abs. rrm review water pollution management water treatment monitoring
1514313,Bosworth and  Venitt 1987,Ampicillin forward mutation assay using escherichia-coli db2,Biosis copyright: biol abs. rrm abstract human fecal mutagens 4 nitroquinoline 1-oxide ethyl methanesulfonate methyl methanesulfonate n methyl-n'-nitro-n-nitrosoguanidine chromium-vi carcinogens,Ampicillin forward mutation assay using escherichia-coli db2 Abs: Biosis copyright: biol abs. rrm abstract human fecal mutagens 4 nitroquinoline 1-oxide ethyl methanesulfonate methyl methanesulfonate n methyl-n'-nitro-n-nitrosoguanidine chromium-vi carcinogens
1514311,Boniardi et al. 1999,Effect of dissolved metals on the organic load removal efficiency of Lemna gibba,"BIOSIS COPYRIGHT: BIOL ABS. This work is focused on assessing the potentialities of Lemna gibba in the treatment of metal polluted wastewaters. This was done by evaluating the effects of various metals on plant growth, bioaccumulation and organic pollutant removal rate. In particular, several experiments were carried out using synthetic wastewaters contaminated with AlIII, CuII, CrVI, FeIII and ZnII at various concentrations. It was found that wastewaters containing organic load with FeIII (up to about 20 mg/l), ZnII (up to about 20 mg/l) and AlIII (less than 30 mg/l) do not affect the performance of a treatment based on Lemna gibba. On the other hand, concentrations of chromium higher than about 0.1 mg/l and copper larger than about 1 mg/l have a detrimental effect on the plant performance.","Effect of dissolved metals on the organic load removal efficiency of Lemna gibba Abs: BIOSIS COPYRIGHT: BIOL ABS. This work is focused on assessing the potentialities of Lemna gibba in the treatment of metal polluted wastewaters. This was done by evaluating the effects of various metals on plant growth, bioaccumulation and organic pollutant removal rate. In particular, several experiments were carried out using synthetic wastewaters contaminated with AlIII, CuII, CrVI, FeIII and ZnII at various concentrations. It was found that wastewaters containing organic load with FeIII (up to about 20 mg/l), ZnII (up to about 20 mg/l) and AlIII (less than 30 mg/l) do not affect the performance of a treatment based on Lemna gibba. On the other hand, concentrations of chromium higher than about 0.1 mg/l and copper larger than about 1 mg/l have a detrimental effect on the plant performance."
1514310,Boiano and  Aw 1983,"Health Hazard Evaluation Report, No. HETA-82-191-1267, Engineered Air Systems, Incorporated (Formerly American Air Filter Company) St. Louis, Missouri","The effects of exposure to sulfur-dioxide (7446095) (SO2) were investigated on April 1 and 2, 1982 at Engineering Air Systems, Incorporated (SIC-348) in St. Louis, Missouri. The evaluation was requested by the Assistant Director of Safety and Health, International Brotherhood of Boilermakers, Iron Ship Builders, Blacksmiths, Forgers, and Helpers following an industrial accident in which SO2 was released when a dip tank was cleaned. The company employed 150 production workers. Information about the accident and general work procedures was reviewed, and medical questionnaires were given to the 40 workers who were seen by physicians following the accident. SO2 was released when sodium-bisulfite (7681381) was added to a dip tank containing chromic-acid (7738945) solution to clean and desludge the tank. The 40 workers experienced cough, chest discomfort, throat irritation, and eye irritation. Review of the workers' medical records concerning the accident did not reveal any X-ray or pulmonary function abnormalities. The authors conclude that acute overexposure to SO2 did occur at the company, but no serious long term health effects are evident. They recommend work practice and engineering controls to prevent reoccurrence of accidents.","Health Hazard Evaluation Report, No. HETA-82-191-1267, Engineered Air Systems, Incorporated (Formerly American Air Filter Company) St. Louis, Missouri Abs: The effects of exposure to sulfur-dioxide (7446095) (SO2) were investigated on April 1 and 2, 1982 at Engineering Air Systems, Incorporated (SIC-348) in St. Louis, Missouri. The evaluation was requested by the Assistant Director of Safety and Health, International Brotherhood of Boilermakers, Iron Ship Builders, Blacksmiths, Forgers, and Helpers following an industrial accident in which SO2 was released when a dip tank was cleaned. The company employed 150 production workers. Information about the accident and general work procedures was reviewed, and medical questionnaires were given to the 40 workers who were seen by physicians following the accident. SO2 was released when sodium-bisulfite (7681381) was added to a dip tank containing chromic-acid (7738945) solution to clean and desludge the tank. The 40 workers experienced cough, chest discomfort, throat irritation, and eye irritation. Review of the workers' medical records concerning the accident did not reveal any X-ray or pulmonary function abnormalities. The authors conclude that acute overexposure to SO2 did occur at the company, but no serious long term health effects are evident. They recommend work practice and engineering controls to prevent reoccurrence of accidents."
1514309,Boiano and  Almaguer 1763,"Health Hazard Evaluation Report No. HETA-85-046-1763, American Crystal Sugar Company, East Grand Forks, Minnesota","Following a request from the American Federation of Grain Millers International Union and management of the American Crystal Sugar Company (ACSCO), employee exposures to airborne contaminants during beet processing and welding fumes during facility maintenance were determined at a sugar beet mill (SIC-2063) owned by ACSCO. Beet processing involved 680 workers, and welding exposed a potential ten to 15 workers to metal fumes. Personal and general air samples were analyzed for chemicals and total and respirable dusts, and total welding fumes and metals were analyzed from personal samples. Analytical methods included chromatography, spectroscopy, X-ray diffraction, and gravimetry. Exposures in excess of the most stringent criteria were found for calcium-oxide (1305788) and calcium-carbonate (471341) in lime kiln workers, sugar dust in sugar bin workers, insoluble hexavalent chromium (18540299) and nickel (7440020) during welding, total welding fumes in one case, and nickel during a metal coating spray process. Quartz (14808607) was found in several settled dust samples and high volume air samples. Nickel and chromium exposures presented potential cancer risks. The authors conclude that workers were overexposed to calcium-oxide, calcium-carbonate, sugar dust, total welding fumes, hexavalent chromium and nickel at this facility. Recommendations include particulate containment, ventilation, and respiratory protection where appropriate.","Health Hazard Evaluation Report No. HETA-85-046-1763, American Crystal Sugar Company, East Grand Forks, Minnesota Abs: Following a request from the American Federation of Grain Millers International Union and management of the American Crystal Sugar Company (ACSCO), employee exposures to airborne contaminants during beet processing and welding fumes during facility maintenance were determined at a sugar beet mill (SIC-2063) owned by ACSCO. Beet processing involved 680 workers, and welding exposed a potential ten to 15 workers to metal fumes. Personal and general air samples were analyzed for chemicals and total and respirable dusts, and total welding fumes and metals were analyzed from personal samples. Analytical methods included chromatography, spectroscopy, X-ray diffraction, and gravimetry. Exposures in excess of the most stringent criteria were found for calcium-oxide (1305788) and calcium-carbonate (471341) in lime kiln workers, sugar dust in sugar bin workers, insoluble hexavalent chromium (18540299) and nickel (7440020) during welding, total welding fumes in one case, and nickel during a metal coating spray process. Quartz (14808607) was found in several settled dust samples and high volume air samples. Nickel and chromium exposures presented potential cancer risks. The authors conclude that workers were overexposed to calcium-oxide, calcium-carbonate, sugar dust, total welding fumes, hexavalent chromium and nickel at this facility. Recommendations include particulate containment, ventilation, and respiratory protection where appropriate."
1514308,Boiano and  Almaguer 1761,"Health Hazard Evaluation Report No. HETA-85-044-1761, American Crystal Sugar Company, Drayton, North Dakota","Employee exposures to airborne contaminants during sugar beet processing and to welding fumes during facility maintenance were evaluated at a sugar beet mill (SIC-2063) owned by the American Crystal Sugar Company (ACSCO), in response to a request from the American Federation of Grain Millers International Union and ACSCO's management. Sugar processing operations involved approximately 370 workers, and welding potentially exposed ten to 15 workers. Personal and general air samples were collected and analyzed for several chemicals, total and respirable dusts, and metals and welding fumes. Methods included gravimetric analysis, chromatography, spectroscopy, and X-ray diffraction. Exposures in excess of the most stringent criteria were found for calcium-oxide (1305788), coal dust, crystalline silica (14808607), sugar dust, and formaldehyde (50000). Areas of greatest exposure included lime kiln operation, coal handling, and storage bin housekeeping. The latter was only an area of potential exposure, since workers wore dust respirators. Detectable formaldehyde levels in general air represented a possible carcinogenic risk. Presence of silica in bulk samples presented a potential risk of silicosis. Exposures to total welding fumes and metals exceeded stringent criteria in two thirds of samples. Potential cancer risks included hexavalent chromium (18540299) and nickel (7440020). Recommendations include use of respiratory protection, dust and fume containment, and formaldehyde replacement.","Health Hazard Evaluation Report No. HETA-85-044-1761, American Crystal Sugar Company, Drayton, North Dakota Abs: Employee exposures to airborne contaminants during sugar beet processing and to welding fumes during facility maintenance were evaluated at a sugar beet mill (SIC-2063) owned by the American Crystal Sugar Company (ACSCO), in response to a request from the American Federation of Grain Millers International Union and ACSCO's management. Sugar processing operations involved approximately 370 workers, and welding potentially exposed ten to 15 workers. Personal and general air samples were collected and analyzed for several chemicals, total and respirable dusts, and metals and welding fumes. Methods included gravimetric analysis, chromatography, spectroscopy, and X-ray diffraction. Exposures in excess of the most stringent criteria were found for calcium-oxide (1305788), coal dust, crystalline silica (14808607), sugar dust, and formaldehyde (50000). Areas of greatest exposure included lime kiln operation, coal handling, and storage bin housekeeping. The latter was only an area of potential exposure, since workers wore dust respirators. Detectable formaldehyde levels in general air represented a possible carcinogenic risk. Presence of silica in bulk samples presented a potential risk of silicosis. Exposures to total welding fumes and metals exceeded stringent criteria in two thirds of samples. Potential cancer risks included hexavalent chromium (18540299) and nickel (7440020). Recommendations include use of respiratory protection, dust and fume containment, and formaldehyde replacement."
1514307,Boiano and  Almaguer 1760,"Health Hazard Evaluation Report No. HETA-85-043-1760, American Crystal Sugar Company, Hillsboro, North Dakota","In response to a request from management of the American Crystal Sugar Company (ACSCO) and the American Federation of Grain Millers International Union, employee exposures to welding fumes during facility maintenance and to airborne contaminants during beet processing were determined at a sugar beet mill (SIC-2063) owned by ACSCO. Beet processing involved 230 workers, while approximately ten to 15 workers were potentially exposed to welding fumes. General air and personal samples were analyzed for total and respirable dusts and various chemicals, and personal filters were analyzed for welding fumes. Analytical methods included X-ray diffraction, spectroscopy, chromatography, and gravimetry. Quartz (14808607) was found in high volume air samples and settled dust. Exposures exceeding the most stringent environmental criteria were found for calcium-carbonate (471341) and carbon-monoxide (630080) in lime kiln workers and sugar dust in sugar bin workers. Beet pulp dust was considered a potential hazard based on its content of crystalline silica. Welding produced excessive exposures to total welding fumes, hexavalent chromium (18540299), nickel (7440020), iron-oxide (1332372), and calcium-oxide (1305788). Chromium and nickel posed potential cancer risks. The authors conclude that workers were overexposed to calcium-carbonate, carbon-monoxide, sugar dust, total welding fumes, hexavalent chromium, iron-oxide, nickel, and calcium-oxide fumes at this facility. The authors recommend dust containment, ventilation, respiratory protection, and correction of slipping hazards.","Health Hazard Evaluation Report No. HETA-85-043-1760, American Crystal Sugar Company, Hillsboro, North Dakota Abs: In response to a request from management of the American Crystal Sugar Company (ACSCO) and the American Federation of Grain Millers International Union, employee exposures to welding fumes during facility maintenance and to airborne contaminants during beet processing were determined at a sugar beet mill (SIC-2063) owned by ACSCO. Beet processing involved 230 workers, while approximately ten to 15 workers were potentially exposed to welding fumes. General air and personal samples were analyzed for total and respirable dusts and various chemicals, and personal filters were analyzed for welding fumes. Analytical methods included X-ray diffraction, spectroscopy, chromatography, and gravimetry. Quartz (14808607) was found in high volume air samples and settled dust. Exposures exceeding the most stringent environmental criteria were found for calcium-carbonate (471341) and carbon-monoxide (630080) in lime kiln workers and sugar dust in sugar bin workers. Beet pulp dust was considered a potential hazard based on its content of crystalline silica. Welding produced excessive exposures to total welding fumes, hexavalent chromium (18540299), nickel (7440020), iron-oxide (1332372), and calcium-oxide (1305788). Chromium and nickel posed potential cancer risks. The authors conclude that workers were overexposed to calcium-carbonate, carbon-monoxide, sugar dust, total welding fumes, hexavalent chromium, iron-oxide, nickel, and calcium-oxide fumes at this facility. The authors recommend dust containment, ventilation, respiratory protection, and correction of slipping hazards."
1514306,Bohgard et al. 1988,Aerosols from thermal spraying operations with materials containing chromium and nickel,"Five common methods of thermal spraying with materials containing chromium (7440473) and nickel (7440020) were characterized regarding the particle size distribution, the elemental composition, the oxidation state of chromium and a measure of the solubility of chromium. Three types of samplers were used: a multifilter sampler for total and respirable fractions, a modified Battelle impactor, and a sampler with two parallel filters prepared for transmission electron microscopy studies. The samplers were placed 50 to 150 centimeters above and 50 to 100 centimeters behind the sprayed object with the inlets facing downwards during sampling. The distance between the nozzle of the spray gun and the object were between 5 and 20 centimeters. The relative abundancies of the major metals in the aerosols agreed with the relative abundancies in the spraying materials. The lower concentrations of the metals in the fume relative to the materials can be explained by the fact that the fumes consist of metal oxides while the spraying materials consist of alloys of the metals. No significant differences were noted in metal composition between different particle size fractions. Significant differences were noted in the chromium-VI concentration in the respirable and total fractions. The concentration of chromium-VI depended on both spraying method and spraying material. The soluble part of chromium-VI was mainly in the respirable fraction for all methods used. Transmission electron microscopy detected generally two classes of particles: coarser spherical particles and finer particles being aggregates of small primary particles. KW - DCN-186552","Aerosols from thermal spraying operations with materials containing chromium and nickel Abs: Five common methods of thermal spraying with materials containing chromium (7440473) and nickel (7440020) were characterized regarding the particle size distribution, the elemental composition, the oxidation state of chromium and a measure of the solubility of chromium. Three types of samplers were used: a multifilter sampler for total and respirable fractions, a modified Battelle impactor, and a sampler with two parallel filters prepared for transmission electron microscopy studies. The samplers were placed 50 to 150 centimeters above and 50 to 100 centimeters behind the sprayed object with the inlets facing downwards during sampling. The distance between the nozzle of the spray gun and the object were between 5 and 20 centimeters. The relative abundancies of the major metals in the aerosols agreed with the relative abundancies in the spraying materials. The lower concentrations of the metals in the fume relative to the materials can be explained by the fact that the fumes consist of metal oxides while the spraying materials consist of alloys of the metals. No significant differences were noted in metal composition between different particle size fractions. Significant differences were noted in the chromium-VI concentration in the respirable and total fractions. The concentration of chromium-VI depended on both spraying method and spraying material. The soluble part of chromium-VI was mainly in the respirable fraction for all methods used. Transmission electron microscopy detected generally two classes of particles: coarser spherical particles and finer particles being aggregates of small primary particles. KW - DCN-186552"
1514305,Bohgard et al. 1979,An Analytical Procedure for Determining Chromium in Samples of Airborne Dust,"An analytical procedure was sought which would be able to give accurate information concerning oxidation states and solubility of chromium (7440473) compounds. The analysis of airborne particulates as presented was able to separate the different oxidation states of chromium and also soluble from insoluble chromium. Samples were taken of particles generated in welding operations in stainless steel. Membrane filters were used for sampling the particles, which were then analyzed by proton induced X-ray emission which measured the total chromium. Electron spectroscopy was used for chemical analysis to measure the oxidation state of chromium on particle surfaces. The portion of water soluble hexavalent chromium (18540299) was determined using sym-diphenylcarbazide. Finally, transmission electron microscopy was used to obtain information about the size and shape of the particles and as an aid in interpreting the data from the electron spectroscopy chemical analysis step. Laboratory generated welding fumes were analyzed by this procedure. Based on results obtained, the authors conclude that the method is suitable for samples consisting of very small particles, and that for larger particles, data can be obtained related to surface concentrations, which may be the most important in health considerations. They suggest that the washing procedure for analysis of water soluble chromium may require modification as more knowledge of lung absorption mechanisms is acquired.","An Analytical Procedure for Determining Chromium in Samples of Airborne Dust Abs: An analytical procedure was sought which would be able to give accurate information concerning oxidation states and solubility of chromium (7440473) compounds. The analysis of airborne particulates as presented was able to separate the different oxidation states of chromium and also soluble from insoluble chromium. Samples were taken of particles generated in welding operations in stainless steel. Membrane filters were used for sampling the particles, which were then analyzed by proton induced X-ray emission which measured the total chromium. Electron spectroscopy was used for chemical analysis to measure the oxidation state of chromium on particle surfaces. The portion of water soluble hexavalent chromium (18540299) was determined using sym-diphenylcarbazide. Finally, transmission electron microscopy was used to obtain information about the size and shape of the particles and as an aid in interpreting the data from the electron spectroscopy chemical analysis step. Laboratory generated welding fumes were analyzed by this procedure. Based on results obtained, the authors conclude that the method is suitable for samples consisting of very small particles, and that for larger particles, data can be obtained related to surface concentrations, which may be the most important in health considerations. They suggest that the washing procedure for analysis of water soluble chromium may require modification as more knowledge of lung absorption mechanisms is acquired."
1514304,Blowes et al. 1997,In-situ remediation of Cr(VI)-contaminated groundwater using permeable reactive walls: Laboratory studies,"BIOSIS COPYRIGHT: BIOL ABS. Permeable-reactive redox walls, placed below the ground surface in the path of flowing groundwater, provide an alternative remediation approach for removing electroactive chemicals from contaminated groundwater. Four types of Fe-bearing solids, siderite (FeCO3), pyrite (FeS2), coarse-grained elemental iron (Fe0), and fine-grained Fe0, were assessed for their ability to remove dissolved Cr(VI) from solution at flow rates typical of those encountered at sites of remediation. Batch studies show that the rate of Cr(VI) removal by fine-grained Fe0 is greater than that for pyrite and coarse-grained Fe0. Results from column studies suggest that partial removal of Cr(VI) by pyrite and coarse-grained Fe0 and quantitative removal of Cr(VI) by fine-grained Fe0 occur at rapid groundwater flow velocities. The removal mechanism for Cr(VI) by fine-grained Fe0 and coarse-grained Fe0 is through the reduction of Cr(VI) to Cr(III), coupled with the oxidation of Fe0 to Fe(II) and Fe(III)","In-situ remediation of Cr(VI)-contaminated groundwater using permeable reactive walls: Laboratory studies Abs: BIOSIS COPYRIGHT: BIOL ABS. Permeable-reactive redox walls, placed below the ground surface in the path of flowing groundwater, provide an alternative remediation approach for removing electroactive chemicals from contaminated groundwater. Four types of Fe-bearing solids, siderite (FeCO3), pyrite (FeS2), coarse-grained elemental iron (Fe0), and fine-grained Fe0, were assessed for their ability to remove dissolved Cr(VI) from solution at flow rates typical of those encountered at sites of remediation. Batch studies show that the rate of Cr(VI) removal by fine-grained Fe0 is greater than that for pyrite and coarse-grained Fe0. Results from column studies suggest that partial removal of Cr(VI) by pyrite and coarse-grained Fe0 and quantitative removal of Cr(VI) by fine-grained Fe0 occur at rapid groundwater flow velocities. The removal mechanism for Cr(VI) by fine-grained Fe0 and coarse-grained Fe0 is through the reduction of Cr(VI) to Cr(III), coupled with the oxidation of Fe0 to Fe(II) and Fe(III)"
1514303,Bloomfield and  Pruden 1980,The behavior of chromium(VI) in soil under aerobic and anaerobic conditions,"HEEP COPYRIGHT: BIOL ABS. (Tris (hydroxymethyl)methylamine effectively removed Cr(VI) absorbed on soil colloids and extracted too little colored organic matter to interfer in absorptiometric determination of Cr(VI) as chromate in alkaline solution. With topsoil from Sawyers filed of Rothamsted Experimental Farm (UK) (Batcombe series), the extent of reduction after 3 wk aerobic incubation increased from 5 mg Cr(VI) reduced/100 g of soil at pH 6.65 to 14 mg/100 g at pH 4.06. Organic contents of soils did not differ greatly (0.8-1.0% organic C) and their efficiency in reducing Cr(VI) increased regularly with decreasing pH. Subsoil did not fit the same sequence as topsoils. It reduced less and absorbed more Cr(VI) than topsoil of the same pH. Under anaerobic conditions Cr(VI) was extensively reduced at pH 6.65 in the presence of 0.5% dried plant matter but the soil alone was only slightly more effective than under aerobic conditions.","The behavior of chromium(VI) in soil under aerobic and anaerobic conditions Abs: HEEP COPYRIGHT: BIOL ABS. (Tris (hydroxymethyl)methylamine effectively removed Cr(VI) absorbed on soil colloids and extracted too little colored organic matter to interfer in absorptiometric determination of Cr(VI) as chromate in alkaline solution. With topsoil from Sawyers filed of Rothamsted Experimental Farm (UK) (Batcombe series), the extent of reduction after 3 wk aerobic incubation increased from 5 mg Cr(VI) reduced/100 g of soil at pH 6.65 to 14 mg/100 g at pH 4.06. Organic contents of soils did not differ greatly (0.8-1.0% organic C) and their efficiency in reducing Cr(VI) increased regularly with decreasing pH. Subsoil did not fit the same sequence as topsoils. It reduced less and absorbed more Cr(VI) than topsoil of the same pH. Under anaerobic conditions Cr(VI) was extensively reduced at pH 6.65 in the presence of 0.5% dried plant matter but the soil alone was only slightly more effective than under aerobic conditions."
1514302,Blanicky et al. 1968,"Potentiometric Titration of Bi, Cu, Cr and V with Ferrous Sulphate Solution in Alkaline Glycerol Medium","A method was developed to determine concentrations of bismuth(III) (23713464) (BiIII), copper(II) (15158119) (CuII), Vanadium(V) (22537311) (V5+) and chromium(VI) (18540299) (Cr6+) by potentiometric titrations. The titrations were carried out with an electron tube potentiometer Acidimeter with a platinum wire indicating electrode and a calomel reference electrode. The titrations were performed in a vessel suitable for titrations in an inert atmosphere. Potassium-hydroxide and glycerol were added to the solution to be analyzed. A stream of nitrogen was passed through the solution for 10 minutes. Without stopping the gas stream, the solution was titrated potentiometrically with a 0.1 to 0.5 Normal ferrous-sulfate solution. This method was able to determine 2 to 45 milligrams (mg) of BiIII, 1.5 to 15mg of CuII, 1 to 25mg of V5+, and 1 to 15mg of Cr6+. The errors of this method were not greater than 1.5 percent. The authors state that this iron and glycerol complex may also be used for the determination of silver(I) (14701214), gold(III) (16065911), mercury(II) (14302875), and palladium(II) (16065886).","Potentiometric Titration of Bi, Cu, Cr and V with Ferrous Sulphate Solution in Alkaline Glycerol Medium Abs: A method was developed to determine concentrations of bismuth(III) (23713464) (BiIII), copper(II) (15158119) (CuII), Vanadium(V) (22537311) (V5+) and chromium(VI) (18540299) (Cr6+) by potentiometric titrations. The titrations were carried out with an electron tube potentiometer Acidimeter with a platinum wire indicating electrode and a calomel reference electrode. The titrations were performed in a vessel suitable for titrations in an inert atmosphere. Potassium-hydroxide and glycerol were added to the solution to be analyzed. A stream of nitrogen was passed through the solution for 10 minutes. Without stopping the gas stream, the solution was titrated potentiometrically with a 0.1 to 0.5 Normal ferrous-sulfate solution. This method was able to determine 2 to 45 milligrams (mg) of BiIII, 1.5 to 15mg of CuII, 1 to 25mg of V5+, and 1 to 15mg of Cr6+. The errors of this method were not greater than 1.5 percent. The authors state that this iron and glycerol complex may also be used for the determination of silver(I) (14701214), gold(III) (16065911), mercury(II) (14302875), and palladium(II) (16065886)."
1514301,Blamoutier et al. 1971,Allergies to metals,Heep copyright: biol abs. human dermatitis nickel chromium platinum potassium bi chromate mercury fulmonate diagnosis,Allergies to metals Abs: Heep copyright: biol abs. human dermatitis nickel chromium platinum potassium bi chromate mercury fulmonate diagnosis
1514300,Blaise et al. 1994,"A bacterial toxicity assay performed with microplates, microluminometry and Microtox reagent","We have developed a procedure for undertaking a Microtox-based test by coupling microplate and microluminometric technologies. Sample dilutions are prepared in a 96-well polystyrene microplate kept at 15 degrees C, while the Microtox reagent and diluent are placed in an opaque, microluminometry-compatible 96-well microplate also kept at 15 degrees C. Exposure begins when sample aliquots are brought into contact with bacterial reagents in the opaque microplate. After specific exposure times (5, 15, 30 and 60 min), bacterial luminescence is rapidly measured by placing the opaque microplate in a microluminometer. Reproducibility of the procedure, as well as general agreement of EC50 end-point values with published reports, is demonstrated herein after toxicity trials with six metals (Ni2+, Cd2+, Zn2+, Pb2+, Cu2+ and Cr6+). Results suggest that a 60-min exposure time may have value in getting more ""sensitivity mileage"" out of this Microtox-based assay. This microplate procedure possesses attractive features that augment sample throughput and information output. Further refinement and validation studies are ongoing in our laboratories.","A bacterial toxicity assay performed with microplates, microluminometry and Microtox reagent Abs: We have developed a procedure for undertaking a Microtox-based test by coupling microplate and microluminometric technologies. Sample dilutions are prepared in a 96-well polystyrene microplate kept at 15 degrees C, while the Microtox reagent and diluent are placed in an opaque, microluminometry-compatible 96-well microplate also kept at 15 degrees C. Exposure begins when sample aliquots are brought into contact with bacterial reagents in the opaque microplate. After specific exposure times (5, 15, 30 and 60 min), bacterial luminescence is rapidly measured by placing the opaque microplate in a microluminometer. Reproducibility of the procedure, as well as general agreement of EC50 end-point values with published reports, is demonstrated herein after toxicity trials with six metals (Ni2+, Cd2+, Zn2+, Pb2+, Cu2+ and Cr6+). Results suggest that a 60-min exposure time may have value in getting more ""sensitivity mileage"" out of this Microtox-based assay. This microplate procedure possesses attractive features that augment sample throughput and information output. Further refinement and validation studies are ongoing in our laboratories."
1514299,Bjorklund et al. 1996,"New method for toxicity assessment in marine and brackish environments using the macroalga Gracilaria tenuistipitata (Gracilariales, Rhodophyta). AU - HAGLUND K","BIOSIS COPYRIGHT: BIOL ABS. A growth inhibition test method was developed using the macroalga Gracilaria tenuistipitata as the test organism. This alga was chosen because of its high laboratory growth rates, commonly 30-40% d-1, which are reached in salinities between 5 and 40 , and its epiphyte resistance. The toxicity of a number of substances, including heavy metals, herbicides and complex wastewaters towards the alga was assayed. Anti-fouling paints were tested with a modification of the method. EC50 values for heavy metals varied between 0.05 and 17 mg l-1 and for herbicides between 0.002 and 0.02 mg l-1. The sensitivity to the toxicant was generally higher at low salinity. Omitting nitrogen and phosphorus additions to the test medium increased the sensitivity and a semi-static performance was possible with maintained or increased sensitivity. Preliminary tests done with a computerised photosynthesis inhibition method produced promising results. In conclusion, this is a simple, sensitive and","New method for toxicity assessment in marine and brackish environments using the macroalga Gracilaria tenuistipitata (Gracilariales, Rhodophyta). AU - HAGLUND K Abs: BIOSIS COPYRIGHT: BIOL ABS. A growth inhibition test method was developed using the macroalga Gracilaria tenuistipitata as the test organism. This alga was chosen because of its high laboratory growth rates, commonly 30-40% d-1, which are reached in salinities between 5 and 40 , and its epiphyte resistance. The toxicity of a number of substances, including heavy metals, herbicides and complex wastewaters towards the alga was assayed. Anti-fouling paints were tested with a modification of the method. EC50 values for heavy metals varied between 0.05 and 17 mg l-1 and for herbicides between 0.002 and 0.02 mg l-1. The sensitivity to the toxicant was generally higher at low salinity. Omitting nitrogen and phosphorus additions to the test medium increased the sensitivity and a semi-static performance was possible with maintained or increased sensitivity. Preliminary tests done with a computerised photosynthesis inhibition method produced promising results. In conclusion, this is a simple, sensitive and"
1514298,Bitton et al. 1992,MetPAD: A bioassay for rapid assessment of heavy metal toxicity in wastewater,"BIOSIS COPYRIGHT: BIOL ABS. MetPAD, a bioassay for the specific determination of heavy metal toxicity, was evaluated for toxicity assessment of industrial effluents. It was shown that MetPAD does not respond to organic toxicants, but is sensitive to heavy metals. Six of nine industrial effluents were shown to be toxic using MetPAD. Chemical analyses of the industrial effluents confirmed the presence of heavy metals. If run concurrently with another test for general toxicity test (for example, Microtox), MetPAD can be a suitable complimentary assay for the specific determination of heavy metal toxicity.","MetPAD: A bioassay for rapid assessment of heavy metal toxicity in wastewater Abs: BIOSIS COPYRIGHT: BIOL ABS. MetPAD, a bioassay for the specific determination of heavy metal toxicity, was evaluated for toxicity assessment of industrial effluents. It was shown that MetPAD does not respond to organic toxicants, but is sensitive to heavy metals. Six of nine industrial effluents were shown to be toxic using MetPAD. Chemical analyses of the industrial effluents confirmed the presence of heavy metals. If run concurrently with another test for general toxicity test (for example, Microtox), MetPAD can be a suitable complimentary assay for the specific determination of heavy metal toxicity."
1514297,Bilello et al. 1984,"Air stripping pilot study of voccontaminated groundwater, volume i","HMTC A pilot study examined the use of air stripping as a method for removing volatile organic compounds (VOCs) from groundwater. Experimenters used a packed column air stripper to test its ability to remove trichloroethylene (TCE), dichloroethylene (DCE), and methylene chloride (MeCl). The results were then used to determine the effects of different matrices, VOC concentrations, stripper designs, and temperatures on the stripper's performance. Air stripping can efficiently remove TCE, DCE, and MeCl. Appendices provide ion exchange resin tests for hexavalent chromium, an analytical method for detecting VOCs, individual test results from the study, and the forms of Henry's Law Constant derived for the study. (10 ref.)","Air stripping pilot study of voccontaminated groundwater, volume i Abs: HMTC A pilot study examined the use of air stripping as a method for removing volatile organic compounds (VOCs) from groundwater. Experimenters used a packed column air stripper to test its ability to remove trichloroethylene (TCE), dichloroethylene (DCE), and methylene chloride (MeCl). The results were then used to determine the effects of different matrices, VOC concentrations, stripper designs, and temperatures on the stripper's performance. Air stripping can efficiently remove TCE, DCE, and MeCl. Appendices provide ion exchange resin tests for hexavalent chromium, an analytical method for detecting VOCs, individual test results from the study, and the forms of Henry's Law Constant derived for the study. (10 ref.)"
1514296,Bignoli 1993,Laboratory experiments and modelling activity to study the migration of pollutants in unsaturated vadose zone and saturated soil porous media,Biosis copyright: biol abs. rrm journal article solute concentration hydraulic property waste disposal ground water pollution management tool analytical method,Laboratory experiments and modelling activity to study the migration of pollutants in unsaturated vadose zone and saturated soil porous media Abs: Biosis copyright: biol abs. rrm journal article solute concentration hydraulic property waste disposal ground water pollution management tool analytical method
1514295,Biggart et al. 1987,Evidence for the presence of mutagenic compounds other than chromium in particles from mild steel welding,Biosis copyright: biol abs. rrm salmonella microsome liquid culture assay respiratory cancer frameshift mutation cell-particle interaction,Evidence for the presence of mutagenic compounds other than chromium in particles from mild steel welding Abs: Biosis copyright: biol abs. rrm salmonella microsome liquid culture assay respiratory cancer frameshift mutation cell-particle interaction
1514294,Bianchi and  Levis 1985,Mechanisms of Chromium Genotoxicity,"Mechanisms of chromium (7440473) genotoxicity are reviewed. The genetic effects of chromium are discussed. Hexavalent chromium (18540299) (Cr(VI)) and trivalent chromium (16065831) (Cr(III)) differ markedly in their ability to damage DNA when tested in simplified systems, such as isolated nuclei and purified DNA, or in intact cells. Cr(VI) is genetically active in intact cells but inactive in simplified systems, whereas Cr(III) is inactive in intact cells, but active in simplified systems. Cr(VI) as chromate ions is transported through cell membranes by a gene controlled mechanism. Chromate ions are reduced intracellularly to Cr(III). Cr(III) binds to free nucleotides as well as to nucleic acids. The ability of Cr(VI) to damage DNA directly while being reduced to Cr(III) is considered questionable. Only Cr(VI) has been shown to be mutagenic in bacterial, yeast, and mammalian assay systems. The chemical and biological properties of Cr(VI) and Cr(III) together with their observed genetic effects suggest several molecular mechanisms for chromium genotoxicity. Genetic effects can originate from the cytoplasmic and nuclear action of oxidizing Cr(VI) or complexing Cr(III) on enzymes or intermediates participating in the synthesis of DNA and its precursors. Genotoxic effects could also arise from oxidation of DNA by Cr(VI) which escaped cytoplasmic reduction, or from the interaction of DNA with Cr(III) produced within the nucleus or reaching it from the cytoplasm or even from outside the cell. The mutagenic activities of Cr(VI) and CR(III) compounds correlate with their carcinogenic activity in animal studies. Cr(III) compounds are not carcinogenic. Cr(VI) compounds show carcinogenic activity, soluble Cr(VI) compounds showing the greatest carcinogenicity. Possible future developments in research on chromium genotoxicity are discussed.","Mechanisms of Chromium Genotoxicity Abs: Mechanisms of chromium (7440473) genotoxicity are reviewed. The genetic effects of chromium are discussed. Hexavalent chromium (18540299) (Cr(VI)) and trivalent chromium (16065831) (Cr(III)) differ markedly in their ability to damage DNA when tested in simplified systems, such as isolated nuclei and purified DNA, or in intact cells. Cr(VI) is genetically active in intact cells but inactive in simplified systems, whereas Cr(III) is inactive in intact cells, but active in simplified systems. Cr(VI) as chromate ions is transported through cell membranes by a gene controlled mechanism. Chromate ions are reduced intracellularly to Cr(III). Cr(III) binds to free nucleotides as well as to nucleic acids. The ability of Cr(VI) to damage DNA directly while being reduced to Cr(III) is considered questionable. Only Cr(VI) has been shown to be mutagenic in bacterial, yeast, and mammalian assay systems. The chemical and biological properties of Cr(VI) and Cr(III) together with their observed genetic effects suggest several molecular mechanisms for chromium genotoxicity. Genetic effects can originate from the cytoplasmic and nuclear action of oxidizing Cr(VI) or complexing Cr(III) on enzymes or intermediates participating in the synthesis of DNA and its precursors. Genotoxic effects could also arise from oxidation of DNA by Cr(VI) which escaped cytoplasmic reduction, or from the interaction of DNA with Cr(III) produced within the nucleus or reaching it from the cytoplasm or even from outside the cell. The mutagenic activities of Cr(VI) and CR(III) compounds correlate with their carcinogenic activity in animal studies. Cr(III) compounds are not carcinogenic. Cr(VI) compounds show carcinogenic activity, soluble Cr(VI) compounds showing the greatest carcinogenicity. Possible future developments in research on chromium genotoxicity are discussed."
1514293,Bhutani et al. 1992,Use of carrier technique for preconcentration of microamounts of Cr(VI): A radioindicator study,"BIOSIS COPYRIGHT: BIOL ABS. Based on a scientific study of the deposition of radioactive 51CrO42- species on ignited microcrystalline sulfates of lead, barium, and strontium along with their subsequent elution, a new experimental procedure for the concentration of aqueous extracts for microgram quantities of chromate species is developed. The feasibility of the procedure has been studied radiometrically on the basis of a systematic examination of the working conditions, e.g., carrying efficiency as a function of pH of the aqueous medium lattice/nonlattice ionic concentration, amount of carrier, carrying capacity of the carrier, and extraction of activity adsorbed under suitable experimental conditions. In principle, the procedure consists of two stages: first, the radioactive tracer species in a dilute aqueous solution is carried out under specified experimental conditions on a small quantity of ignited selected carriers; second, the carried activity can be largely leached out in a minimal amount","Use of carrier technique for preconcentration of microamounts of Cr(VI): A radioindicator study Abs: BIOSIS COPYRIGHT: BIOL ABS. Based on a scientific study of the deposition of radioactive 51CrO42- species on ignited microcrystalline sulfates of lead, barium, and strontium along with their subsequent elution, a new experimental procedure for the concentration of aqueous extracts for microgram quantities of chromate species is developed. The feasibility of the procedure has been studied radiometrically on the basis of a systematic examination of the working conditions, e.g., carrying efficiency as a function of pH of the aqueous medium lattice/nonlattice ionic concentration, amount of carrier, carrying capacity of the carrier, and extraction of activity adsorbed under suitable experimental conditions. In principle, the procedure consists of two stages: first, the radioactive tracer species in a dilute aqueous solution is carried out under specified experimental conditions on a small quantity of ignited selected carriers; second, the carried activity can be largely leached out in a minimal amount"
1514292,Bhide et al. 1996,Microbiological process for the removal of Cr(VI) from chromate-bearing cooling tower effluent,"BIOSIS COPYRIGHT: BIOL ABS. A microbiological process using Pseudomonas mendocina was developed for the removal of Cr(VI) from cooling tower effluent. The process, when carried out in a 20 liter continuous stirred tank reactor removed 25-100 mg chromate/l in 4.5-8 h with > 99.9% efficiency in the presence of sugarcane molasses as nutrient. The process could sustain wide variations in pH (6.5-9.5), temperature (25ê C-40ê C) and was unaffected by commonly used biocides.","Microbiological process for the removal of Cr(VI) from chromate-bearing cooling tower effluent Abs: BIOSIS COPYRIGHT: BIOL ABS. A microbiological process using Pseudomonas mendocina was developed for the removal of Cr(VI) from cooling tower effluent. The process, when carried out in a 20 liter continuous stirred tank reactor removed 25-100 mg chromate/l in 4.5-8 h with > 99.9% efficiency in the presence of sugarcane molasses as nutrient. The process could sustain wide variations in pH (6.5-9.5), temperature (25ê C-40ê C) and was unaffected by commonly used biocides."
1514291,Bertoglio Riolo et al. 1972,"Oscillopolarographic determination of Cu(II), Cd(II), Pb(II), Zn(II), Ni(II), Mn(II) and Cr(VI) in waste waters","HEEP COPYRIGHT: BIOL ABS. Experimental conditions were investigated for the determination of Cu(II), Cd(II), Pb(II), Zn(II), Ni(II), Mn(II) and Cr(VI) in waste waters by oscillographic polarography. For all of these elements, analytical sensitivity and precision of this method are reported. The influence of the most common agents which cause interference is also reported. Results are in good agreement with atomic absorption spectroscopic analysis and confirm that the oscillopolarography is a suitable and reliable method for routine determinations in waste water.","Oscillopolarographic determination of Cu(II), Cd(II), Pb(II), Zn(II), Ni(II), Mn(II) and Cr(VI) in waste waters Abs: HEEP COPYRIGHT: BIOL ABS. Experimental conditions were investigated for the determination of Cu(II), Cd(II), Pb(II), Zn(II), Ni(II), Mn(II) and Cr(VI) in waste waters by oscillographic polarography. For all of these elements, analytical sensitivity and precision of this method are reported. The influence of the most common agents which cause interference is also reported. Results are in good agreement with atomic absorption spectroscopic analysis and confirm that the oscillopolarography is a suitable and reliable method for routine determinations in waste water."
1514290,Berlin et al. 2985,"The toxicology of chemicals - 1. Carcinogenicity, Volume 1 - summary reviews of the scientific evidence","36 reviews covering 64 substances are presented in this volume. In each review the data is presented under the following headings: introduction, animal data, mutagenic and genotoxic information, human data, scientific conclusions, need for further work, references.","The toxicology of chemicals - 1. Carcinogenicity, Volume 1 - summary reviews of the scientific evidence Abs: 36 reviews covering 64 substances are presented in this volume. In each review the data is presented under the following headings: introduction, animal data, mutagenic and genotoxic information, human data, scientific conclusions, need for further work, references."
1514289,Benhra et al. 1997,Cryoalgotox: Use of cryopreserved alga in a semistatic microplate test,"BIOSIS COPYRIGHT: BIOL ABS. Use of cryopreserved alga Selenastrum capricornutum has been evaluated as a simple and cost-efficient procedure in a new semistatic algal ecotoxicity test. Experiments have been conducted to compare performance criteria of this method, named Cryoalgotox, versus the classic microplate test using fresh algae. Cryoalgotox 72-h 50% effective concentrations (EC50s) determined with Cd2+, Cu2+, Cr6+, and atrazine were more sensitive, repeatable (low coefficients of variation), and reproducible (low time effect) than the results obtained with the classical microplate tests. The effect of storage time at -80êC on the sensitivity of the algae was assessed using cadmium as a toxic reference; it was shown that algae stored at -80êC over a 3-month period gave comparable toxicity results to those found with fresh algae.","Cryoalgotox: Use of cryopreserved alga in a semistatic microplate test Abs: BIOSIS COPYRIGHT: BIOL ABS. Use of cryopreserved alga Selenastrum capricornutum has been evaluated as a simple and cost-efficient procedure in a new semistatic algal ecotoxicity test. Experiments have been conducted to compare performance criteria of this method, named Cryoalgotox, versus the classic microplate test using fresh algae. Cryoalgotox 72-h 50% effective concentrations (EC50s) determined with Cd2+, Cu2+, Cr6+, and atrazine were more sensitive, repeatable (low coefficients of variation), and reproducible (low time effect) than the results obtained with the classical microplate tests. The effect of storage time at -80êC on the sensitivity of the algae was assessed using cadmium as a toxic reference; it was shown that algae stored at -80êC over a 3-month period gave comparable toxicity results to those found with fresh algae."
1514288,Bengtsson et al. 1999,Assessment of duckweed Lemna aequinoctialis as a toxicological bioassay for tropical environments in developing countries,"BIOSIS COPYRIGHT: BIOL ABS. The tropical duckweed Lemna aequinoctialis Welwitsch (Lemnaceae) was collected in Thailand and the Philippines, so that an efficient toxicological bioassay for tropical environments could be developed. Optimal conditions required for conducting ecotoxicological growth tests were investigated and the resulting test manual was used to test the effects of heavy metals (Cd2+, Cr6+, Cu2+, Hg2+, Zn2+), ClO3-, 3,5-dichlorophenol and phenol on the growth of the two strains of duckweed. The effect on gro","Assessment of duckweed Lemna aequinoctialis as a toxicological bioassay for tropical environments in developing countries Abs: BIOSIS COPYRIGHT: BIOL ABS. The tropical duckweed Lemna aequinoctialis Welwitsch (Lemnaceae) was collected in Thailand and the Philippines, so that an efficient toxicological bioassay for tropical environments could be developed. Optimal conditions required for conducting ecotoxicological growth tests were investigated and the resulting test manual was used to test the effects of heavy metals (Cd2+, Cr6+, Cu2+, Hg2+, Zn2+), ClO3-, 3,5-dichlorophenol and phenol on the growth of the two strains of duckweed. The effect on gro"
1514287,Bello et al. 1999,Retention of Cr(VI) and Hg(II) in Eucalyptus globulus- and peach stone-activated carbons,"BIOSIS COPYRIGHT: BIOL ABS. Retention rate of Cr(VI) and Hg(II), from an aqueous medium by activated carbons obtained from peach stones and Eucalyptus globulus chips, is reported. To describe the retention rate of these ions, the effects of the activated carbon preparation variables: activating agent (steam and CO2), and burn-off, are analyzed. In addition, the effect of the following adsorption process variable: initial concentration of the metallic ion, system temperature, pH of the medium and particle size of the adsorb chemical functionality of the activated carbon surface and the retention is enhanced when carbon dioxide is used as activating agent, whereas Cr(VI) retention is higher when steam activation is used.","Retention of Cr(VI) and Hg(II) in Eucalyptus globulus- and peach stone-activated carbons Abs: BIOSIS COPYRIGHT: BIOL ABS. Retention rate of Cr(VI) and Hg(II), from an aqueous medium by activated carbons obtained from peach stones and Eucalyptus globulus chips, is reported. To describe the retention rate of these ions, the effects of the activated carbon preparation variables: activating agent (steam and CO2), and burn-off, are analyzed. In addition, the effect of the following adsorption process variable: initial concentration of the metallic ion, system temperature, pH of the medium and particle size of the adsorb chemical functionality of the activated carbon surface and the retention is enhanced when carbon dioxide is used as activating agent, whereas Cr(VI) retention is higher when steam activation is used."
1514286,Beceiro-Gonzalez et al. 1992,Separation of chromium(III) and chromium(VI) using complexation of chromium(III) with 8-hydroxyquinoline and determination of both species in waters by ETA-AAS,"BIOSIS COPYRIGHT: BIOL ABS. A method for the determination of chromium(III) and (VI) species has been studied and applied to mineral water samples. The chromium(III) was chelated with 0.1 mol/l 8-hydroxyquinoline in methyl alcohol, extracted in isobutyl methyl ketone and determined by ETA-AAS. The effects of the pH, extraction and heating time and amounts of the reagents required for the extraction were studied. A method for the determination of total chromium was optimized too, and the chromium(VI) can be calculated. The precision, sensibility, accuracy, graphite furnace program and interferences for both methods were also investigated.","Separation of chromium(III) and chromium(VI) using complexation of chromium(III) with 8-hydroxyquinoline and determination of both species in waters by ETA-AAS Abs: BIOSIS COPYRIGHT: BIOL ABS. A method for the determination of chromium(III) and (VI) species has been studied and applied to mineral water samples. The chromium(III) was chelated with 0.1 mol/l 8-hydroxyquinoline in methyl alcohol, extracted in isobutyl methyl ketone and determined by ETA-AAS. The effects of the pH, extraction and heating time and amounts of the reagents required for the extraction were studied. A method for the determination of total chromium was optimized too, and the chromium(VI) can be calculated. The precision, sensibility, accuracy, graphite furnace program and interferences for both methods were also investigated."
1514285,Beaubien et al. 1994,Chromium speciation and distribution in the Great Lakes,"BIOSIS COPYRIGHT: BIOL ABS. A technique is described for selectively measuring the forms of chromium in freshwater samples, with detection limits of 21 ng L-1 for Cr(III), 4 ng L-1 for Cr(VI), and 8 ng L-1 for colloidal/organic Cr. Recovery of the Cr(VI) and Cr(III) spikes were consistently > 90%, but only about 70% for the added organic Cr. When the method was applied to samples from Lake Ontario, it was found that Cr(VI) made up 75-85% of the dissolved Cr and that Cr(III) was consistently below the analytical detection limit. About 10% of the dissolved Cr was in the colloidal/organic form. Average concentrations of total dissolved Cr in the epilimnetic waters were found to be 69 ng L-1 in Lake Superior, 136 ng L-1 in Lake Erie, and 351 ng L-1 in Lake Ontario. The increasing concentration of Cr down the Great Lakes watershed reflects the conservative geochemical behavior of Cr(VI) and the increasing input of Cr from industrial and municipal sources.","Chromium speciation and distribution in the Great Lakes Abs: BIOSIS COPYRIGHT: BIOL ABS. A technique is described for selectively measuring the forms of chromium in freshwater samples, with detection limits of 21 ng L-1 for Cr(III), 4 ng L-1 for Cr(VI), and 8 ng L-1 for colloidal/organic Cr. Recovery of the Cr(VI) and Cr(III) spikes were consistently > 90%, but only about 70% for the added organic Cr. When the method was applied to samples from Lake Ontario, it was found that Cr(VI) made up 75-85% of the dissolved Cr and that Cr(III) was consistently below the analytical detection limit. About 10% of the dissolved Cr was in the colloidal/organic form. Average concentrations of total dissolved Cr in the epilimnetic waters were found to be 69 ng L-1 in Lake Superior, 136 ng L-1 in Lake Erie, and 351 ng L-1 in Lake Ontario. The increasing concentration of Cr down the Great Lakes watershed reflects the conservative geochemical behavior of Cr(VI) and the increasing input of Cr from industrial and municipal sources."
1514284,Batley and  Matousek 1980,Determination of chromium speciation in natural waters by electrodeposition on graphite tubes for electrothermal atomization,"HEEP COPYRIGHT: BIOL ABS. An analytical technique was developed for the study of Cr speciation in natural waters based on the atomization of electrodeposited species. Matrix interferences can be overcome and preconcentration achieved by the electrodeposition of Cr with Hg, onto pyrolytic graphite-coated tubular furnaces, using a flow-through assembly. At pH 4.7, using a deposition potential of -1.8 V vs. SCE (saturated calomel electrode), both Cr(VI) and Cr(III) are reduced and accumulated as metallic Cr. At the same pH, but at -0.3 V vs. SCE, only Cr(VI) is selectively reduced to Cr(III) which accumulates by adsorption. Using the labile-bound discrimination of the electrodeposition technique combined with an UV irradiation step, Cr(VI) was dominant in the samples studied, with most Cr(VI) present as labile forms.","Determination of chromium speciation in natural waters by electrodeposition on graphite tubes for electrothermal atomization Abs: HEEP COPYRIGHT: BIOL ABS. An analytical technique was developed for the study of Cr speciation in natural waters based on the atomization of electrodeposited species. Matrix interferences can be overcome and preconcentration achieved by the electrodeposition of Cr with Hg, onto pyrolytic graphite-coated tubular furnaces, using a flow-through assembly. At pH 4.7, using a deposition potential of -1.8 V vs. SCE (saturated calomel electrode), both Cr(VI) and Cr(III) are reduced and accumulated as metallic Cr. At the same pH, but at -0.3 V vs. SCE, only Cr(VI) is selectively reduced to Cr(III) which accumulates by adsorption. Using the labile-bound discrimination of the electrodeposition technique combined with an UV irradiation step, Cr(VI) was dominant in the samples studied, with most Cr(VI) present as labile forms."
1514283,Bassi et al. 1990,"Effects of chromium (VI) on two freshwater plants, Lemna minor and Pistia stratiotes 1 morphological observations","BIOSIS COPYRIGHT: BIOL ABS. Lemna minor and Pistia stratiotes were grown in nutrient solution to which K2Cr2O7 was added to give final concentrations of Cr(VI) varying from 0.1 to 20 ppm. In both plants the main effects were retardation of growth, chlorosis and wilting. Ultrastructural alterations were brought about by even lower doses of the metal, such as 0.1 and 1 ppm, respectively, and concerned primarily the plasma membrane, and also the thylakoids. In developing cells the proplastids failed to develop into normal chloroplasts and the nuclei had aberrant shapes. It is suggested that one of the major consequences of Cr poisoning is damage to the plasma membrane.","Effects of chromium (VI) on two freshwater plants, Lemna minor and Pistia stratiotes 1 morphological observations Abs: BIOSIS COPYRIGHT: BIOL ABS. Lemna minor and Pistia stratiotes were grown in nutrient solution to which K2Cr2O7 was added to give final concentrations of Cr(VI) varying from 0.1 to 20 ppm. In both plants the main effects were retardation of growth, chlorosis and wilting. Ultrastructural alterations were brought about by even lower doses of the metal, such as 0.1 and 1 ppm, respectively, and concerned primarily the plasma membrane, and also the thylakoids. In developing cells the proplastids failed to develop into normal chloroplasts and the nuclei had aberrant shapes. It is suggested that one of the major consequences of Cr poisoning is damage to the plasma membrane."
1514282,Bartlett and  James 1979,Behavior of chromium in soils: III. Oxidation,"HEEP COPYRIGHT: BIOL ABS. Although reduced Cr is the stable form in soils, added trivalent Cr oxidizes readily to the hexavalent form, toxic to plants and animals, under conditions prevalent in many field soils. The key to the oxidation apparently is the presence in the soil of oxidized Mn, which serves as the electron acceptor in the reaction. The relative ability of a soil to oxidize Cr may be predicted by measuring Mn reducible by hydroquinone, or it may be determined directly by means of a quick test in which Cr(III) is added to a fresh moist soil sample. Oxidation of Cr by soils was not discovered earlier because the importance of studying fresh field soils, rather than crushed, dried, stored samples, was not appreciated. Plants were severely damaged by Cr(VI) formed from Cr(III) added to fresh soil samples. Hexavalent Cr still was present in a soil stored moist at 25ê C for 5 mo.","Behavior of chromium in soils: III. Oxidation Abs: HEEP COPYRIGHT: BIOL ABS. Although reduced Cr is the stable form in soils, added trivalent Cr oxidizes readily to the hexavalent form, toxic to plants and animals, under conditions prevalent in many field soils. The key to the oxidation apparently is the presence in the soil of oxidized Mn, which serves as the electron acceptor in the reaction. The relative ability of a soil to oxidize Cr may be predicted by measuring Mn reducible by hydroquinone, or it may be determined directly by means of a quick test in which Cr(III) is added to a fresh moist soil sample. Oxidation of Cr by soils was not discovered earlier because the importance of studying fresh field soils, rather than crushed, dried, stored samples, was not appreciated. Plants were severely damaged by Cr(VI) formed from Cr(III) added to fresh soil samples. Hexavalent Cr still was present in a soil stored moist at 25ê C for 5 mo."
1514280,Aw and  Stephenson 1983,"Health hazard evaluation report no. HETA-82-113-1374, Mainstreet Enterprises, Lebanon, Indiana","In response to a request from the director of Mainstreet Enterprises (SIC-3273), a nonprofit rehabilitation sheltered workshop in Lebanon, Indiana, an evaluation was made of the occurrence of benign breast tumors among female workers exposed to concrete dust during packaging of dry powdered concrete mortar mix (Fix-Crete). Bulk samples of the finished Fix-Crete were collected to be analyzed for asbestos (1332214), crystalline silica (7631869), hexavalent chromium (18540299), and total chromium (7440473) content. Hexavalent chromium was found at concentrations of 32 micrograms per gram (microg/g) of bulk material. Total chromium, asbestos and silica were not detectable. Respirable particulate concentrations ranged from 0.8 to 2.3 milligrams per cubic meter (mg/m3). Total particulates ranged from 2.9 to 34.3mg/m3. After minor modifications of the ventilation system were made, retesting indicated personal breathing zone and air samples for respirable particulates averaged 0.5 and 1.1mg/m3, respectively. Total particulates ranged from 1.7 to 13.8mg/m3. No significant differences in the prevalence of benign breast tumors was noted in supervisors working on the concrete powder process when compared to those who did not work in this area. The authors conclude that there was an exposure to dust for one task. No evidence was found to link the occurrence of benign breast tumors to chemical exposures at the facility. The authors recommend that a further reduction of the mixer operator's exposure be brought about through effective engineering controls. Respirators should be used where appropriate. Vacuum cleaning equipment should be used to collect debris from the clothing of personnel and rehabilitees instead of compressed air. Protective gloves and cleaning and washing facilities should be made available.","Health hazard evaluation report no. HETA-82-113-1374, Mainstreet Enterprises, Lebanon, Indiana Abs: In response to a request from the director of Mainstreet Enterprises (SIC-3273), a nonprofit rehabilitation sheltered workshop in Lebanon, Indiana, an evaluation was made of the occurrence of benign breast tumors among female workers exposed to concrete dust during packaging of dry powdered concrete mortar mix (Fix-Crete). Bulk samples of the finished Fix-Crete were collected to be analyzed for asbestos (1332214), crystalline silica (7631869), hexavalent chromium (18540299), and total chromium (7440473) content. Hexavalent chromium was found at concentrations of 32 micrograms per gram (microg/g) of bulk material. Total chromium, asbestos and silica were not detectable. Respirable particulate concentrations ranged from 0.8 to 2.3 milligrams per cubic meter (mg/m3). Total particulates ranged from 2.9 to 34.3mg/m3. After minor modifications of the ventilation system were made, retesting indicated personal breathing zone and air samples for respirable particulates averaged 0.5 and 1.1mg/m3, respectively. Total particulates ranged from 1.7 to 13.8mg/m3. No significant differences in the prevalence of benign breast tumors was noted in supervisors working on the concrete powder process when compared to those who did not work in this area. The authors conclude that there was an exposure to dust for one task. No evidence was found to link the occurrence of benign breast tumors to chemical exposures at the facility. The authors recommend that a further reduction of the mixer operator's exposure be brought about through effective engineering controls. Respirators should be used where appropriate. Vacuum cleaning equipment should be used to collect debris from the clothing of personnel and rehabilitees instead of compressed air. Protective gloves and cleaning and washing facilities should be made available."
1514279,Atkinson et al. 1998,Waste activated sludge remediation of metal-plating effluents,"BIOSIS COPYRIGHT: BIOL ABS. Waste activated sludge is capable of binding and removing metal ions from solution. Sludge was exposed to an industrial metalplating effluent, containing a range of heavy metals, in order to assess its bioadsorptive capacity. Experiments were conducted in fully mixed reactors on a batch basis. Greatest affinity was shown for the Zn cation which consistently proved to be present in untreated waste water samples in the highest concentration. Although Zn dominated the forward adsorption reaction, ionic competition amongst the other metals analysed showed Cr3+ and Cu to be the most weakly bound, often displaced to the soluble phase by other metal contaminants. Three agents viz., HCl, H2SO4 and NaCl, were assessed for their ability to desorb immobilised metals from the surface of the sludge biomass. Based upon performance and cost, H2SO4 showed greatest potential for further experimentation and process optimisation. This study shows that waste activated sludge, with further","Waste activated sludge remediation of metal-plating effluents Abs: BIOSIS COPYRIGHT: BIOL ABS. Waste activated sludge is capable of binding and removing metal ions from solution. Sludge was exposed to an industrial metalplating effluent, containing a range of heavy metals, in order to assess its bioadsorptive capacity. Experiments were conducted in fully mixed reactors on a batch basis. Greatest affinity was shown for the Zn cation which consistently proved to be present in untreated waste water samples in the highest concentration. Although Zn dominated the forward adsorption reaction, ionic competition amongst the other metals analysed showed Cr3+ and Cu to be the most weakly bound, often displaced to the soluble phase by other metal contaminants. Three agents viz., HCl, H2SO4 and NaCl, were assessed for their ability to desorb immobilised metals from the surface of the sludge biomass. Based upon performance and cost, H2SO4 showed greatest potential for further experimentation and process optimisation. This study shows that waste activated sludge, with further"
1514277,Asada et al. 1973,Report of analyses for industrial waste water in twenty-eight factories,"HEEP COPYRIGHT: BIOL ABS. Factories (28) were classified into 3 categories: factories of hard were (metal goods), of food goods, of cement goods and others. To determine whether industrial waste water fulfilled the water quality standards of Tsuchiura city (Japan), analytical experiments were carried out from April 1972-April 1973 for: pH, chemical oxygen demand (COD), suspended solids (SS), phenol, alkalinity, NH4 +--N, NO-+2-N, Cl--, CN--, Cu-2+, Pb-2+, Fe-3+, Mn-2+, Cd-2+, Cr-6+, ions, total Cr and number of coliform bacteria. Excessive CN--, Zn-2+, Cr-6+, OH-- ions and SS were often in the drainage from some metal product plants. Excess number of coliform bacteria, COD and SS were in the industrial waste water from food product plants. Cr-6+ ion was detected in samples from cement goods factories. River pollution was caused mainly by industrial waste waters from metal product plants and food product plants, and urban sewage drainage.","Report of analyses for industrial waste water in twenty-eight factories Abs: HEEP COPYRIGHT: BIOL ABS. Factories (28) were classified into 3 categories: factories of hard were (metal goods), of food goods, of cement goods and others. To determine whether industrial waste water fulfilled the water quality standards of Tsuchiura city (Japan), analytical experiments were carried out from April 1972-April 1973 for: pH, chemical oxygen demand (COD), suspended solids (SS), phenol, alkalinity, NH4 +--N, NO-+2-N, Cl--, CN--, Cu-2+, Pb-2+, Fe-3+, Mn-2+, Cd-2+, Cr-6+, ions, total Cr and number of coliform bacteria. Excessive CN--, Zn-2+, Cr-6+, OH-- ions and SS were often in the drainage from some metal product plants. Excess number of coliform bacteria, COD and SS were in the industrial waste water from food product plants. Cr-6+ ion was detected in samples from cement goods factories. River pollution was caused mainly by industrial waste waters from metal product plants and food product plants, and urban sewage drainage."
1514276,Arpadjan and  Krivan 2611,Preatomization Separation of Chromium(III) from Chromium(VI) in the Graphite Furnace,"The separation of chromium(III) (7440473) from chromium(VI) in different media via volatilization of chromium(III)-trifluoroacetylacetonate in the graphite furnace was investigated. Doubly distilled water, rain water, Danube River water, and urine samples were examined. Trifluoroacetylacetone, 10 milliliters (ml), 20ml 25 percent tetramethylammonium-hydroxide solution in methyl-alcohol, and 20ml of a 0.5 molar aqueous sodium-acetate solution were mixed, allowed to sit at room temperature for 1 hour, and then water samples were mixed with equal volumes of the solution; urine samples were diluted with three times their volumes. Aliquots of 5 to 20 microliters of the samples were injected into the tube which was then placed in the furnace. The temperature program consisted of an increase to 130 degrees-C over 20 seconds for drying with a hold time of 40 seconds; a 1 second increase to 400 degrees for chromium(III) volatilization (hold time 300 seconds); a 10 second increase to 1200 degrees for charring (40 second hold time); and a 1 second increase to 2700 degrees for atomization (hold time 10 seconds). Results were compared to those obtained with atomic absorption spectrometry. Yields for preatomization removal of chromium(III) were higher with tungsten coated tubes than with uncoated or pyrolytically coated tubes. In the temperature range 400 to 1000 degrees, 90 percent chromium(III) was removed for uncoated and coated tubes without the Lvov platform and 96 percent from tungsten coated tubes without the Lvov platform. Chromium(VI) was quantitatively retained in all types of tubes in the temperature range from 200 to 1200 degrees. Comparison with atomic absorption spectrometric results showed good agreement. The authors conclude that this procedure provides a simple method for the determination of chromium(VI) in the presence of chromium(III).","Preatomization Separation of Chromium(III) from Chromium(VI) in the Graphite Furnace Abs: The separation of chromium(III) (7440473) from chromium(VI) in different media via volatilization of chromium(III)-trifluoroacetylacetonate in the graphite furnace was investigated. Doubly distilled water, rain water, Danube River water, and urine samples were examined. Trifluoroacetylacetone, 10 milliliters (ml), 20ml 25 percent tetramethylammonium-hydroxide solution in methyl-alcohol, and 20ml of a 0.5 molar aqueous sodium-acetate solution were mixed, allowed to sit at room temperature for 1 hour, and then water samples were mixed with equal volumes of the solution; urine samples were diluted with three times their volumes. Aliquots of 5 to 20 microliters of the samples were injected into the tube which was then placed in the furnace. The temperature program consisted of an increase to 130 degrees-C over 20 seconds for drying with a hold time of 40 seconds; a 1 second increase to 400 degrees for chromium(III) volatilization (hold time 300 seconds); a 10 second increase to 1200 degrees for charring (40 second hold time); and a 1 second increase to 2700 degrees for atomization (hold time 10 seconds). Results were compared to those obtained with atomic absorption spectrometry. Yields for preatomization removal of chromium(III) were higher with tungsten coated tubes than with uncoated or pyrolytically coated tubes. In the temperature range 400 to 1000 degrees, 90 percent chromium(III) was removed for uncoated and coated tubes without the Lvov platform and 96 percent from tungsten coated tubes without the Lvov platform. Chromium(VI) was quantitatively retained in all types of tubes in the temperature range from 200 to 1200 degrees. Comparison with atomic absorption spectrometric results showed good agreement. The authors conclude that this procedure provides a simple method for the determination of chromium(VI) in the presence of chromium(III)."
1514275,Arpadjan and  Krivan 1986,Preatomization separation of chromium-iii from chromium-vi in the graphite furnace,Biosis copyright: biol abs. rrm environmental samples urine nutrition toxicity,Preatomization separation of chromium-iii from chromium-vi in the graphite furnace Abs: Biosis copyright: biol abs. rrm environmental samples urine nutrition toxicity
1514274,Arnfalk et al. 1996,"A comparative study of Cd, Cr(III), Cr(VI), Hg, and Pb uptake by minerals and soil materials","BIOSIS COPYRIGHT: BIOL ABS. The pH dependency of Cd, Cr(III), Cr(VI), Hg, and Ph uptake by 14 different types of minerals and soil materials has been studied. The solids were interacted with metal solutions separately in a batch procedure, and the percentage of metal uptake of different metal-solid combinations was compared and evaluated. The results were quantified by the pH values at which 10, 50 and 90% of the metal uptake took place. Physical and chemical characteristics of the solids were correlated with metal uptake. The results verify the importance of geochemical parameters of soils such as organic content, type of clay mineral, presence of complexing ions, and redox-potential for controlling metal uptake. Retention of Cd, Cr(VI), Hg, and Ph was found to be strongly dependent on organic content of the materials studied. Montmorillonite (in bentonite and smectite) showed the highest uptake of Cd, Cr(III) and Ph among all minerals and soil materials, while illite and kaolinite showed lower u","A comparative study of Cd, Cr(III), Cr(VI), Hg, and Pb uptake by minerals and soil materials Abs: BIOSIS COPYRIGHT: BIOL ABS. The pH dependency of Cd, Cr(III), Cr(VI), Hg, and Ph uptake by 14 different types of minerals and soil materials has been studied. The solids were interacted with metal solutions separately in a batch procedure, and the percentage of metal uptake of different metal-solid combinations was compared and evaluated. The results were quantified by the pH values at which 10, 50 and 90% of the metal uptake took place. Physical and chemical characteristics of the solids were correlated with metal uptake. The results verify the importance of geochemical parameters of soils such as organic content, type of clay mineral, presence of complexing ions, and redox-potential for controlling metal uptake. Retention of Cd, Cr(VI), Hg, and Ph was found to be strongly dependent on organic content of the materials studied. Montmorillonite (in bentonite and smectite) showed the highest uptake of Cd, Cr(III) and Ph among all minerals and soil materials, while illite and kaolinite showed lower u"
1514273,Armienta et al. 1996,"Distribution, origin and fate of chromium in soils in Guanajuato, Mexico","BIOSIS COPYRIGHT: BIOL ABS. Total, hexavalent and trivalent chromium were determined in surface and 30-cm depth soil samples from a highly chromium-polluted area in Guanajuato state, central Mexico. Four samples were also analyzed by a sequential extraction Procedure. Nearly 0.9 km2 out of the 8 km2 area sampled was polluted with chromium, at concentrations up to 12960 mg kg-1, mostly as Cr(III). Concentrations of Cr(VI) were lower than 0.5 mg kg-1 in most sampled points, with the exception of one, where the concentration was found to be 65.14 mg kg-1. Chromium-containing dust from a chromate factory accounted for most of the contamination. The highest concentrations of hexavalent chromium in soil, were in the bottom sediments of an abandoned water reservoir used to store polluted water from a well, before use of the water in the factory process. Tannery wastes, dust from a sanitary landfill of chromate compounds and the transport of chromium products are the sources of chromium at other sites. C","Distribution, origin and fate of chromium in soils in Guanajuato, Mexico Abs: BIOSIS COPYRIGHT: BIOL ABS. Total, hexavalent and trivalent chromium were determined in surface and 30-cm depth soil samples from a highly chromium-polluted area in Guanajuato state, central Mexico. Four samples were also analyzed by a sequential extraction Procedure. Nearly 0.9 km2 out of the 8 km2 area sampled was polluted with chromium, at concentrations up to 12960 mg kg-1, mostly as Cr(III). Concentrations of Cr(VI) were lower than 0.5 mg kg-1 in most sampled points, with the exception of one, where the concentration was found to be 65.14 mg kg-1. Chromium-containing dust from a chromate factory accounted for most of the contamination. The highest concentrations of hexavalent chromium in soil, were in the bottom sediments of an abandoned water reservoir used to store polluted water from a well, before use of the water in the factory process. Tannery wastes, dust from a sanitary landfill of chromate compounds and the transport of chromium products are the sources of chromium at other sites. C"
1514272,Armienta and  Quere 1995,"Hydrogeochemical behavior of chromium in the unsaturated zone and in the aquifer of Leon Valley, Mexico","BIOSIS COPYRIGHT: BIOL ABS. The ground water of Leon valley, Central Mexico, is contaminated with chromium. A study was carried out to determine the main physico-chemical interactions between chromium and the aquifer solid matrix in the most polluted area. Five boreholes, 30 m deep, were drilled and used as piezometers. Unaltered solid cores were analyzed for Cr(VI), total Cr, Fe and Mn. Cr(VI) was determined in the water from the piezometers. We conclude that reduction of Cr(VI) by iron is important, adsorption of Cr(VI) by sand and gravel layers is negligible, and adsorption by silt and clay layers is significant in the saturated and unsaturated zones. In the saturated zone hexavalent chromium distributes preferentially in the water phase, oxidation of chromium by manganese was not detected. A correlation between chromium, manganese and iron concentrations was observed for the aquifer solid matrix in this area, when the source of chromium was not anthropogenic.","Hydrogeochemical behavior of chromium in the unsaturated zone and in the aquifer of Leon Valley, Mexico Abs: BIOSIS COPYRIGHT: BIOL ABS. The ground water of Leon valley, Central Mexico, is contaminated with chromium. A study was carried out to determine the main physico-chemical interactions between chromium and the aquifer solid matrix in the most polluted area. Five boreholes, 30 m deep, were drilled and used as piezometers. Unaltered solid cores were analyzed for Cr(VI), total Cr, Fe and Mn. Cr(VI) was determined in the water from the piezometers. We conclude that reduction of Cr(VI) by iron is important, adsorption of Cr(VI) by sand and gravel layers is negligible, and adsorption by silt and clay layers is significant in the saturated and unsaturated zones. In the saturated zone hexavalent chromium distributes preferentially in the water phase, oxidation of chromium by manganese was not detected. A correlation between chromium, manganese and iron concentrations was observed for the aquifer solid matrix in this area, when the source of chromium was not anthropogenic."
1514271,Arillo and  Melodia 1991,Reduction of hexavalent chromium by the earthworm Eisenia foetida (Savigny),BIOSIS COPYRIGHT: BIOL ABS. Several metabolic systems in Eisenia foetida competent to achieve an intracellular Cr(VI) reduction are described. Evidence that earthworms act as effective scavengers of hexavalent chromium from the environment is also provided. Results suggest that E. foetida may play an important role during occasional Cr(VI) pollution of soils.,Reduction of hexavalent chromium by the earthworm Eisenia foetida (Savigny) Abs: BIOSIS COPYRIGHT: BIOL ABS. Several metabolic systems in Eisenia foetida competent to achieve an intracellular Cr(VI) reduction are described. Evidence that earthworms act as effective scavengers of hexavalent chromium from the environment is also provided. Results suggest that E. foetida may play an important role during occasional Cr(VI) pollution of soils.
1514270,Arillo and  Melodia 1990,Protective effect of fish mucus against chromium(VI) pollution,"BIOSIS COPYRIGHT: BIOL ABS. Skin mucus from Salmo gairdneri contains some molecules (probably protein-bound sulfhydryl groups) able to reduce hexavalent chromium (Cr-VI). Results suggest also that fish slime layer can markedly decrease the Cr(VI) penetration-rate in animal tissues. For these reasons, mucus is regarded as a protective barrier against Cr(VI) pollution, especially during occasional and short lasting exposures to metal.","Protective effect of fish mucus against chromium(VI) pollution Abs: BIOSIS COPYRIGHT: BIOL ABS. Skin mucus from Salmo gairdneri contains some molecules (probably protein-bound sulfhydryl groups) able to reduce hexavalent chromium (Cr-VI). Results suggest also that fish slime layer can markedly decrease the Cr(VI) penetration-rate in animal tissues. For these reasons, mucus is regarded as a protective barrier against Cr(VI) pollution, especially during occasional and short lasting exposures to metal."
1514269,Arcoria et al. 1976,"Research and determination of some heavy metals in waste waters in the Catania industrial zone, Italy","HEEP COPYRIGHT: BIOL ABS. Results of a series of examinations of heavy metals in waste waters of industrial zone of Catania (Italy) are quoted. Determinations were recorded by atomic absorption spectroscopy or spectrophotometry. Results are discussed in terms of typology of industries present, their location and characteristics of discharge.","Research and determination of some heavy metals in waste waters in the Catania industrial zone, Italy Abs: HEEP COPYRIGHT: BIOL ABS. Results of a series of examinations of heavy metals in waste waters of industrial zone of Catania (Italy) are quoted. Determinations were recorded by atomic absorption spectroscopy or spectrophotometry. Results are discussed in terms of typology of industries present, their location and characteristics of discharge."
1514268,Archundia et al. 1993,Reduction of low concentration chromium-vi in acid solutions,Biosis copyright: biol abs. rrm toxicity radiation effects water pollution control heavy metals transport storage ph,Reduction of low concentration chromium-vi in acid solutions Abs: Biosis copyright: biol abs. rrm toxicity radiation effects water pollution control heavy metals transport storage ph
1514267,Arar et al. 1992,Determination of hexavalent chromium in sludge incinerator emissions using ion chromatography and inductively coupled plasma mass spectrometry,"BIOSIS COPYRIGHT: BIOL ABS. A unique approach is described using ion chromatography (IC) and inductively coupled plasma mass spectrometry (ICP-MS) for the determination of hexavalent chromium (Cr(VI)) in wastewater sludge incinerator emission. Quartz fiber filters, spiked with an isotopically enriched (50Cr or 53Cr) chromate salt, were used to collect emission particulates. The enriched Cr(VI) isotope was used to monitor the reduction of Cr(VI) during sample collection using a pseudo-first-order reaction model and to calculate the rate of deposition of native (Cr(VI) on the filters. At the end of the sampling period, the Cr(VI) was extracted from the filters with 0.1 N sodium hydroxide and determined by IC using postcolumn derivatization with 1,5-diphenylcarbohydrazide. To determine the ratio of enriched Cr(VI) to the native Cr(VI) emitted from the incinerator, an additional aliquot of the sample extract was preconcentrated by IC and the isotopic composition of the Cr(VI) fraction determined by ICP","Determination of hexavalent chromium in sludge incinerator emissions using ion chromatography and inductively coupled plasma mass spectrometry Abs: BIOSIS COPYRIGHT: BIOL ABS. A unique approach is described using ion chromatography (IC) and inductively coupled plasma mass spectrometry (ICP-MS) for the determination of hexavalent chromium (Cr(VI)) in wastewater sludge incinerator emission. Quartz fiber filters, spiked with an isotopically enriched (50Cr or 53Cr) chromate salt, were used to collect emission particulates. The enriched Cr(VI) isotope was used to monitor the reduction of Cr(VI) during sample collection using a pseudo-first-order reaction model and to calculate the rate of deposition of native (Cr(VI) on the filters. At the end of the sampling period, the Cr(VI) was extracted from the filters with 0.1 N sodium hydroxide and determined by IC using postcolumn derivatization with 1,5-diphenylcarbohydrazide. To determine the ratio of enriched Cr(VI) to the native Cr(VI) emitted from the incinerator, an additional aliquot of the sample extract was preconcentrated by IC and the isotopic composition of the Cr(VI) fraction determined by ICP"
1514266,Anthony et al. 1993,Selective adsorption and ion exchange of metal cations and anions with silico-titanates and layered titanates,Biosis copyright: biol abs. rrm meeting paper cesium strontium ii aqueous wastes radioactive wastes metal removal,Selective adsorption and ion exchange of metal cations and anions with silico-titanates and layered titanates Abs: Biosis copyright: biol abs. rrm meeting paper cesium strontium ii aqueous wastes radioactive wastes metal removal
1514263,Anonymous 1999,Chromium; total Chromium 1997; hexavalent Chromium 1999,"Total Chromium In the case of total chromium, the SQGE for agricultural and residential/parkland land uses is based on the geometric mean of the preliminary soil contact value and the nutrient and energy cycling check. For commercial and industrial land uses, the SQGE is based on the soil contact guideline. Hexavalent Chromium There are insufficient data to derive any of the environmental health guidelines or check values for Cr(VI). There are, however, sufficient data to derive a provisional SQGE based on soil contact for plants. Soil Quality Guidelines for Human Health Total Chromium Human health soil quality guidelines (SQGHHS) for total chromium are derived using a TDI for the most sensitive receptor designated for a land use. For total chromium, the upper range values of the ESADDIS recommended by, the U.S. National Research Council (NAS 1989) for adults and young children (age 1 to 3 years) are adopted as TDIS for the derivation of SQGHHS. The soil ingestion guidelines for total chromium have been approved by, the Standards and Guidelines Rulings Committee of the Bureau of Chemical Hazards of Health Canada as a preliminary SQGHH. However, the CCME recommends the application of various check mechanisms, when relevant, in order to provide a broader scope of protection. The lowest of the soil ingestion guideline, the inhalation of indoor air check, the off-site migration check, and the groundwater for drinking water check is recommended as the SQGHH. Therefore, the SQGHHS for agricultural, residential/ parkland, and commercial land uses are based on the soil ingestion guidelines. For industrial land use, the SQGHH is based on the off-site migration check. Hexavalent Chromium There are no human health guidelines or check values for Cr(VI) at the present time. Soil Quality Guidelines for Total Chromium The soil quality guidelines are the lower of the SQGHH and the SQGE. For all land uses, the soil quality guideline for total chromium is the soil concentration calculated for the SQGE, which is based on the soil contact guideline. Because there are sufficient data to derive an SQGHH and an SQGE for each land use, the soil quality guidelines represent fully integrated de novo guidelines, derived according to the soil protocol (CCME 1996b). The interim soil quality criteria (CCME 1991) for total chromium are superseded by the soil quality guidelines. Soil Quality Guidelines for Hexavalent Chromium The soil quality, guidelines are the lower of the provisional SQGE and the interim soil quality criteria (CCME 1991). Agricultural and Residential/Parkland The provisional SQGES are less than the interim soil quality criteria (CCME 1991) for agricultural and residential/parkland land uses. Therefore the soil quality guidelines for Cr(V1) supersede the interim soil quality"" criteria for these land uses. Commercial and Industrial Land There are no interim soil quality criteria (CCME 1991) for Cr(VI) for commercial and industrial land uses, and only provisional SQGES can be derived at present. Therefore, the soil quality guidelines for these land uses are the provisional SQGES. CCME (1996b) provides guidance on potential modifications to the final recommended soil quality guideline when setting site-specific objectives.","Chromium; total Chromium 1997; hexavalent Chromium 1999 Abs: Total Chromium In the case of total chromium, the SQGE for agricultural and residential/parkland land uses is based on the geometric mean of the preliminary soil contact value and the nutrient and energy cycling check. For commercial and industrial land uses, the SQGE is based on the soil contact guideline. Hexavalent Chromium There are insufficient data to derive any of the environmental health guidelines or check values for Cr(VI). There are, however, sufficient data to derive a provisional SQGE based on soil contact for plants. Soil Quality Guidelines for Human Health Total Chromium Human health soil quality guidelines (SQGHHS) for total chromium are derived using a TDI for the most sensitive receptor designated for a land use. For total chromium, the upper range values of the ESADDIS recommended by, the U.S. National Research Council (NAS 1989) for adults and young children (age 1 to 3 years) are adopted as TDIS for the derivation of SQGHHS. The soil ingestion guidelines for total chromium have been approved by, the Standards and Guidelines Rulings Committee of the Bureau of Chemical Hazards of Health Canada as a preliminary SQGHH. However, the CCME recommends the application of various check mechanisms, when relevant, in order to provide a broader scope of protection. The lowest of the soil ingestion guideline, the inhalation of indoor air check, the off-site migration check, and the groundwater for drinking water check is recommended as the SQGHH. Therefore, the SQGHHS for agricultural, residential/ parkland, and commercial land uses are based on the soil ingestion guidelines. For industrial land use, the SQGHH is based on the off-site migration check. Hexavalent Chromium There are no human health guidelines or check values for Cr(VI) at the present time. Soil Quality Guidelines for Total Chromium The soil quality guidelines are the lower of the SQGHH and the SQGE. For all land uses, the soil quality guideline for total chromium is the soil concentration calculated for the SQGE, which is based on the soil contact guideline. Because there are sufficient data to derive an SQGHH and an SQGE for each land use, the soil quality guidelines represent fully integrated de novo guidelines, derived according to the soil protocol (CCME 1996b). The interim soil quality criteria (CCME 1991) for total chromium are superseded by the soil quality guidelines. Soil Quality Guidelines for Hexavalent Chromium The soil quality, guidelines are the lower of the provisional SQGE and the interim soil quality criteria (CCME 1991). Agricultural and Residential/Parkland The provisional SQGES are less than the interim soil quality criteria (CCME 1991) for agricultural and residential/parkland land uses. Therefore the soil quality guidelines for Cr(V1) supersede the interim soil quality"" criteria for these land uses. Commercial and Industrial Land There are no interim soil quality criteria (CCME 1991) for Cr(VI) for commercial and industrial land uses, and only provisional SQGES can be derived at present. Therefore, the soil quality guidelines for these land uses are the provisional SQGES. CCME (1996b) provides guidance on potential modifications to the final recommended soil quality guideline when setting site-specific objectives."
1514261,Anonymous 1973,Threshold Limit Values for Chemical Substances and Physical Agents in the Workroom Environment with Intended Changes for 1973,"The threshold limit value is listed for chromium (7440473), and soluble chromic and chromous salts as 0.5 milligram per cubic meter. Human carcinogens and certain insoluble forms of chromates are listed, with the latter assigned a threshold limit value of 100 micrograms per cubic meter. KW - DCN-179039","Threshold Limit Values for Chemical Substances and Physical Agents in the Workroom Environment with Intended Changes for 1973 Abs: The threshold limit value is listed for chromium (7440473), and soluble chromic and chromous salts as 0.5 milligram per cubic meter. Human carcinogens and certain insoluble forms of chromates are listed, with the latter assigned a threshold limit value of 100 micrograms per cubic meter. KW - DCN-179039"
1514260,Anonymous 1970,Mineral Facts and Problems,"Chromium (7440473) occurs in nature only in a combined state. It is found in a large number of minerals, the only one of commercial importance being chromite (1308312). Current mining practices involve both open pit and underground methods, with the latter supplying the major part of the world's chromite ore. Techniques used in mining vary, with the more modern equipment found to a greater extent in the more developed countries which usually have higher labor costs. Chromite of metallurgical grade is converted into ferrochromium or other chromium additives and usually finds its way into special steels or alloys. Chromium metal is made either by electrochemical or pyrochemical methods. Research currently being conducted by industry on chromium concerns application of the metal and the ore to metallurgical, chemical, and refractory uses. Apparent reserves of chromite in the world are discussed.","Mineral Facts and Problems Abs: Chromium (7440473) occurs in nature only in a combined state. It is found in a large number of minerals, the only one of commercial importance being chromite (1308312). Current mining practices involve both open pit and underground methods, with the latter supplying the major part of the world's chromite ore. Techniques used in mining vary, with the more modern equipment found to a greater extent in the more developed countries which usually have higher labor costs. Chromite of metallurgical grade is converted into ferrochromium or other chromium additives and usually finds its way into special steels or alloys. Chromium metal is made either by electrochemical or pyrochemical methods. Research currently being conducted by industry on chromium concerns application of the metal and the ore to metallurgical, chemical, and refractory uses. Apparent reserves of chromite in the world are discussed."
1514258,Anon 1998,"Joint UK-Hebrew University of Jerusalem Seminar on Agriculture and the Clean Environment (Rehovot, Israel; March 16-17, 1998)","BIOSIS COPYRIGHT: BIOL ABS. This meeting contains abstracts of 11 papers, written in English, covering methods to reduce agrochemical applications in crop protection and phytoremediation and other bioremediation procedures against metallic and other pollutants.","Joint UK-Hebrew University of Jerusalem Seminar on Agriculture and the Clean Environment (Rehovot, Israel; March 16-17, 1998) Abs: BIOSIS COPYRIGHT: BIOL ABS. This meeting contains abstracts of 11 papers, written in English, covering methods to reduce agrochemical applications in crop protection and phytoremediation and other bioremediation procedures against metallic and other pollutants."
1514257,Anon 1983,Environmental health perspectives: Proceedings of the second international workshop on in vitro effects of mineral dusts,"The 59 papers presented at this workshop (25-28 Apr. 1984, Arkadelphia, Arkansas, USA) are reproduced. Topics covered: in vitro tests and asbestos-related problems; mineral dusts and fibres; chrysotile; asbestos; amosite; fibrous ferroactinolite; silicate dusts; amphiboles; silica; mesothelioma; fibrosarcoma; experimental silicosis; quartz; non-fibrous dusts; coal and oil flyash; calcium silicates; welding fume particles; welders; nickel compounds; hexavalent chromium; kaolinite; asbestosis; slate mine dust; crocidolite; benzopyrenes.","Environmental health perspectives: Proceedings of the second international workshop on in vitro effects of mineral dusts Abs: The 59 papers presented at this workshop (25-28 Apr. 1984, Arkadelphia, Arkansas, USA) are reproduced. Topics covered: in vitro tests and asbestos-related problems; mineral dusts and fibres; chrysotile; asbestos; amosite; fibrous ferroactinolite; silicate dusts; amphiboles; silica; mesothelioma; fibrosarcoma; experimental silicosis; quartz; non-fibrous dusts; coal and oil flyash; calcium silicates; welding fume particles; welders; nickel compounds; hexavalent chromium; kaolinite; asbestosis; slate mine dust; crocidolite; benzopyrenes."
1514255,Andrle et al. 1997,Speciation of chromium using reversed phase-high performance liquid chromatography coupled to different spectrometric detection methods,"BIOSIS COPYRIGHT: BIOL ABS. Speciation of Cr(III) and Cr(VI) based on the formation of different complexes with ammonium-pyrrolidinedithioate (APDC) in a continuous flow technique and their preconcentration using solid phase extraction (SPE) have been elaborated and applied to the analysis of waste waters from the galvanic industry. The Cr complexes were separated and determined using reversed phase-high performance liquid chromatography (RP-HPLC) coupled to different detection methods, namely UV-detection, graphite furnace-atomic absorption spectrometry (GF-AAS) and inductively coupled plasma mass spectrometry with hydraulic high pressure nebulization (HHPN-MS). After optimization the detection limits for Cr(III) and Cr(VI) of all methods are at the mug l-1 level and the precision in terms of RSD is 5% (cCr = 10 mug l-1, N = 10). The procedure was applied to the determination of Cr(III) and Cr(VI) at the mug l-1 level in galvanic waste waters, and its accuracy was approved by comparing the result","Speciation of chromium using reversed phase-high performance liquid chromatography coupled to different spectrometric detection methods Abs: BIOSIS COPYRIGHT: BIOL ABS. Speciation of Cr(III) and Cr(VI) based on the formation of different complexes with ammonium-pyrrolidinedithioate (APDC) in a continuous flow technique and their preconcentration using solid phase extraction (SPE) have been elaborated and applied to the analysis of waste waters from the galvanic industry. The Cr complexes were separated and determined using reversed phase-high performance liquid chromatography (RP-HPLC) coupled to different detection methods, namely UV-detection, graphite furnace-atomic absorption spectrometry (GF-AAS) and inductively coupled plasma mass spectrometry with hydraulic high pressure nebulization (HHPN-MS). After optimization the detection limits for Cr(III) and Cr(VI) of all methods are at the mug l-1 level and the precision in terms of RSD is 5% (cCr = 10 mug l-1, N = 10). The procedure was applied to the determination of Cr(III) and Cr(VI) at the mug l-1 level in galvanic waste waters, and its accuracy was approved by comparing the result"
1514254,Andrle and  Broekaert 1993,Speciation of chromium(III) and chromium(VI) by reversed phase high-performance liquid chromatography using UV-detection,"BIOSIS COPYRIGHT: BIOL ABS. A method for the simultaneous determination of Cr(III) and Cr(VI) in water samples is described. The different reaction products of Cr(III) and Cr(VI) species with ammonium pyrrolidinedithiocarbamate (APDC) are extracted with ethyl acetate and determined by reversed phase HPLC using UV-detection. The procedure is optimized and its detection limit accordingly improved as compared to literature data. The detection limits achieved are 2.4 mug/l for Cr(III) and 2.1 mug/l for Cr(VI) and the calibration curves are linear between 5 mug/l and 5000 mug/l. For the speciation of Cr, APDC was demonstrated to be more suitable as chelating agent than sodium diethyldithiocarbamate (NaDDC). The procedure was applied to the determination or both Cr species in galvanic waste waters and its accuracy was approved by comparing the results (at the 100 mug/l level) with those of a photometric determination of Cr(VI) species.","Speciation of chromium(III) and chromium(VI) by reversed phase high-performance liquid chromatography using UV-detection Abs: BIOSIS COPYRIGHT: BIOL ABS. A method for the simultaneous determination of Cr(III) and Cr(VI) in water samples is described. The different reaction products of Cr(III) and Cr(VI) species with ammonium pyrrolidinedithiocarbamate (APDC) are extracted with ethyl acetate and determined by reversed phase HPLC using UV-detection. The procedure is optimized and its detection limit accordingly improved as compared to literature data. The detection limits achieved are 2.4 mug/l for Cr(III) and 2.1 mug/l for Cr(VI) and the calibration curves are linear between 5 mug/l and 5000 mug/l. For the speciation of Cr, APDC was demonstrated to be more suitable as chelating agent than sodium diethyldithiocarbamate (NaDDC). The procedure was applied to the determination or both Cr species in galvanic waste waters and its accuracy was approved by comparing the results (at the 100 mug/l level) with those of a photometric determination of Cr(VI) species."
1514253,Anderson et al. 1984,A method for chromate removal from cooling tower blowdown water,HEEP COPYRIGHT: BIOL ABS. Efficient removal of soluble Cr(VI) and precipitated Cr(III) was demonstrated in the laboratory. The process utilizes ferrous ions to reduce the Cr(VI) species and fine magnetite to act as a nucleation and weighting agent. By this means the hydrous metal oxides are removed effectively and rapidly from suspension. The absorbed metal flocs may be removed from the magnetite by mechanical or chemical means to allow reuse of the magnetite. This process for the removal of chromate could be competitive with the existing ferrous sulfate reduction-flocculation and ion-exchange processes.,A method for chromate removal from cooling tower blowdown water Abs: HEEP COPYRIGHT: BIOL ABS. Efficient removal of soluble Cr(VI) and precipitated Cr(III) was demonstrated in the laboratory. The process utilizes ferrous ions to reduce the Cr(VI) species and fine magnetite to act as a nucleation and weighting agent. By this means the hydrous metal oxides are removed effectively and rapidly from suspension. The absorbed metal flocs may be removed from the magnetite by mechanical or chemical means to allow reuse of the magnetite. This process for the removal of chromate could be competitive with the existing ferrous sulfate reduction-flocculation and ion-exchange processes.
1514252,Anderson et al. 1992,Batch experiments characterizing the reduction of chromium-vi using suboxic material from a mildly reducing sand and gravel aquifer,Biosis copyright: biol abs. rrm abstract water pollution control soil pollution control groundwater purification,Batch experiments characterizing the reduction of chromium-vi using suboxic material from a mildly reducing sand and gravel aquifer Abs: Biosis copyright: biol abs. rrm abstract water pollution control soil pollution control groundwater purification
1514251,Al-Shawi and  Dahl 1999,Determination of total chromium in phosphate rocks by ion chromatography,"BIOSIS COPYRIGHT: BIOL ABS. Chromium(VI) is one of seven elements which is classified in the fertilizer industry as being harmful to plants and biological systems. Phosphate rocks represent the raw material for complex fertilizer production in the world. This paper investigates for the first time the determination of total chromium in phosphate rocks by ion chromatography. The developed analytical method involves the digestion of phosphate rocks with nitric acid followed by sample treatment of the resulting solution. The d erent phosphate rocks with atomic absorption spectrometry and inductively coupled plasma atomic emission spectrometry techniques, and cross-analysis data against an internationally certified phosphate rock standard were between 0.58 and 1.45%. Calibration curve between 0.2 and 0.9 mug/ml was excellent, and the method has a detection limit for Cr(VI) of 0.05 ng. The developed method offers a fast, a reliable and an alternative procedure for the determination of total chromium in p","Determination of total chromium in phosphate rocks by ion chromatography Abs: BIOSIS COPYRIGHT: BIOL ABS. Chromium(VI) is one of seven elements which is classified in the fertilizer industry as being harmful to plants and biological systems. Phosphate rocks represent the raw material for complex fertilizer production in the world. This paper investigates for the first time the determination of total chromium in phosphate rocks by ion chromatography. The developed analytical method involves the digestion of phosphate rocks with nitric acid followed by sample treatment of the resulting solution. The d erent phosphate rocks with atomic absorption spectrometry and inductively coupled plasma atomic emission spectrometry techniques, and cross-analysis data against an internationally certified phosphate rock standard were between 0.58 and 1.45%. Calibration curve between 0.2 and 0.9 mug/ml was excellent, and the method has a detection limit for Cr(VI) of 0.05 ng. The developed method offers a fast, a reliable and an alternative procedure for the determination of total chromium in p"
1514250,Al-Sabti and  Metcalfe 1995,Fish micronuclei for assessing genotoxicity in water,"BIOSIS COPYRIGHT: BIOL ABS. Micronucleus assays with fish have been shown to be useful in vivo techniques for genotoxicity testing, and show potential for in situ monitoring of water quality. In this paper, we review the literature on the clastogenic effects of chemical and physical agents on fish cells, with emphasis on the induction of micronuclei in teleosts. Included in the review is a description of the mechanisms for formation of micronuclei in cells, and a summary of the various techniques that have been used for micronucleus analysis in fish. This review is directed to assisting laboratories in the development of fish genotoxicity assays for water quality monitoring.","Fish micronuclei for assessing genotoxicity in water Abs: BIOSIS COPYRIGHT: BIOL ABS. Micronucleus assays with fish have been shown to be useful in vivo techniques for genotoxicity testing, and show potential for in situ monitoring of water quality. In this paper, we review the literature on the clastogenic effects of chemical and physical agents on fish cells, with emphasis on the induction of micronuclei in teleosts. Included in the review is a description of the mechanisms for formation of micronuclei in cells, and a summary of the various techniques that have been used for micronucleus analysis in fish. This review is directed to assisting laboratories in the development of fish genotoxicity assays for water quality monitoring."
1514249,Alonso-Chamarro et al. 1992,Sandwich techniques in flow-injection analysis part 3. simultaneous determination of chromium-vi in two concentration ranges,Biosis copyright: biol abs. rrm flow system spectrophotometry water samples environmental monitoring analytical method,Sandwich techniques in flow-injection analysis part 3. simultaneous determination of chromium-vi in two concentration ranges Abs: Biosis copyright: biol abs. rrm flow system spectrophotometry water samples environmental monitoring analytical method
1514248,Almanza et al. 1996,Rapid toxicity assessment of water-soluble chemicals using a fed-batch reactor technique,"BIOSIS COPYRIGHT: BIOL ABS. A rapid and sensitive technique for determining chemical inhibition of water-soluble compounds by using a fed-batch reactor is presented. A synthetic activated sludge was obtained through the isolation and purification of six different colony types from a domestic effluent. Through the synthetic activate sludge technique, the effect of different concentrations of chromium and copper solutions on the respiration rate of a mixture of bacteria was established. The percent inhibition (% IC) of the microbial respiration was calculated by comparing it to the control mixture without the test substance. The results showed a %IC50 of 33 mg for Cr6+ and 6.5 mg/L for Cu2+. Inhibition kinetic parameters with the fed-batch reactor technique were evaluated. Both inhibitory and noninhibitory responses of chromium and copper were studied using a synthetic activate sludge. Substrate utilization rates and oxygen consumption rates started to be affected when the toxicant reached concentra","Rapid toxicity assessment of water-soluble chemicals using a fed-batch reactor technique Abs: BIOSIS COPYRIGHT: BIOL ABS. A rapid and sensitive technique for determining chemical inhibition of water-soluble compounds by using a fed-batch reactor is presented. A synthetic activated sludge was obtained through the isolation and purification of six different colony types from a domestic effluent. Through the synthetic activate sludge technique, the effect of different concentrations of chromium and copper solutions on the respiration rate of a mixture of bacteria was established. The percent inhibition (% IC) of the microbial respiration was calculated by comparing it to the control mixture without the test substance. The results showed a %IC50 of 33 mg for Cr6+ and 6.5 mg/L for Cu2+. Inhibition kinetic parameters with the fed-batch reactor technique were evaluated. Both inhibitory and noninhibitory responses of chromium and copper were studied using a synthetic activate sludge. Substrate utilization rates and oxygen consumption rates started to be affected when the toxicant reached concentra"
1514247,Almaguer et al. 1984,"Health hazard evaluation report no. HETA-83-296-1491, Johnson Controls, Incorporated, Watertown, Wisconsin","Environmental and breathing zone samples were analyzed for hydrogen-chloride (7647010), chromic-acid (13530682), trichloroethylene (79016), xylene (1330207), methylethylketone (78933), and 1,1,1-trichloroethane (71556) at Johnson Controls, Incorporated (SIC-3822), Watertown, Wisconsin in August, 1983. The evaluation was requested because of union concern of possible exposure to chemicals used at the facility. Medical questionnaires were administered to 13 employees in the assembly department. The ventilation systems were inspected. Two breathing zone samples obtained in the metal treating room contained 6.1 and 24.9 parts per million (ppm) trichloroethylene. Area samples contained 0.1 to 0.6ppm. The OSHA standard for trichloroethylene is 100ppm. Traces of trichloroethylene were found on the roof of the air makeup unit for the assembly department. Exposures of the other substances were well below relevant standards. Symptoms of eye, nose, throat, and sinus irritation were reported. The metal treating room was found to be under negative pressure. The authors conclude that a health hazard does not exist at the facility. Employee symptoms are due to exhaust emissions entering the facility through makeup units on the roof. Recommendations include raising the exhaust stacks to prevent emissions entering the facility and discontinuing the use of trichloroethylene, a suspected carcinogen.","Health hazard evaluation report no. HETA-83-296-1491, Johnson Controls, Incorporated, Watertown, Wisconsin Abs: Environmental and breathing zone samples were analyzed for hydrogen-chloride (7647010), chromic-acid (13530682), trichloroethylene (79016), xylene (1330207), methylethylketone (78933), and 1,1,1-trichloroethane (71556) at Johnson Controls, Incorporated (SIC-3822), Watertown, Wisconsin in August, 1983. The evaluation was requested because of union concern of possible exposure to chemicals used at the facility. Medical questionnaires were administered to 13 employees in the assembly department. The ventilation systems were inspected. Two breathing zone samples obtained in the metal treating room contained 6.1 and 24.9 parts per million (ppm) trichloroethylene. Area samples contained 0.1 to 0.6ppm. The OSHA standard for trichloroethylene is 100ppm. Traces of trichloroethylene were found on the roof of the air makeup unit for the assembly department. Exposures of the other substances were well below relevant standards. Symptoms of eye, nose, throat, and sinus irritation were reported. The metal treating room was found to be under negative pressure. The authors conclude that a health hazard does not exist at the facility. Employee symptoms are due to exhaust emissions entering the facility through makeup units on the roof. Recommendations include raising the exhaust stacks to prevent emissions entering the facility and discontinuing the use of trichloroethylene, a suspected carcinogen."
1514245,Almaguer and  Boiano 1762,"Health Hazard Evaluation Report No. HETA-85-045-1762, American Crystal Sugar Co., Crookston, Minnesota","Employee exposures to airborne contaminants during sugar beet processing and to welding fumes during facility maintenance were evaluated at a sugar beet mill (SIC-2063) owned by the American Crystal Sugar Company (ACSCO), in response to a request from ACSCO's management and the American Federation of Grain Millers International Union. Sugar processing operations involved approximately 375 workers, and maintenance included about 175 of these workers. During beet processing, personal breathing zone and general air samples were collected and analyzed for several chemicals and total and respirable particulates of various dusts. Welding fumes were analyzed by inductively coupled plasma/atomic emission spectroscopy of personal filter samples. The following exposures were considered excessive by the most stringent criteria: lime kiln helper to total particulates (9.6 and 11.2mg/m3), Weibul storage bin housekeeper to sugar dust (13.4mg/m3), diffuser operator and charger to formaldehyde (50000) (0.05 to 0.09mg/m3), and welders and cutters to total welding fumes (2.3 to 84mg/m3) and specific metals, particularly hexavalent chromium (18540299) (0.003 to 0.426mg/m3) and nickel (7440020) (0.002 to 4.17mg/m3). High volume air and settled dust samples contained crystalline silica (14808607), representing a potential hazard. Recommendations include improved particulate containment and ventilation, use of respirators where appropriate, and formaldehyde replacement.","Health Hazard Evaluation Report No. HETA-85-045-1762, American Crystal Sugar Co., Crookston, Minnesota Abs: Employee exposures to airborne contaminants during sugar beet processing and to welding fumes during facility maintenance were evaluated at a sugar beet mill (SIC-2063) owned by the American Crystal Sugar Company (ACSCO), in response to a request from ACSCO's management and the American Federation of Grain Millers International Union. Sugar processing operations involved approximately 375 workers, and maintenance included about 175 of these workers. During beet processing, personal breathing zone and general air samples were collected and analyzed for several chemicals and total and respirable particulates of various dusts. Welding fumes were analyzed by inductively coupled plasma/atomic emission spectroscopy of personal filter samples. The following exposures were considered excessive by the most stringent criteria: lime kiln helper to total particulates (9.6 and 11.2mg/m3), Weibul storage bin housekeeper to sugar dust (13.4mg/m3), diffuser operator and charger to formaldehyde (50000) (0.05 to 0.09mg/m3), and welders and cutters to total welding fumes (2.3 to 84mg/m3) and specific metals, particularly hexavalent chromium (18540299) (0.003 to 0.426mg/m3) and nickel (7440020) (0.002 to 4.17mg/m3). High volume air and settled dust samples contained crystalline silica (14808607), representing a potential hazard. Recommendations include improved particulate containment and ventilation, use of respirators where appropriate, and formaldehyde replacement."
1514244,Almaguer and  Boiano 1759,"Health Hazard Evaluation Report No. HETA-85-018-1759, American Crystal Sugar Company, Moorhead, Minnesota","A sugar beet mill (SIC-2063) owned by the American Crystal Sugar Company (ACSCO) was evaluated for worker exposure to airborne contaminants during beet processing and welding fumes during facility maintenance, following a request from ACSCO management and the American Federation of Grain Millers International Union. Beet processing involved approximately 690 workers, while maintenance involved approximately 300 of these workers. Total and respirable dusts were measured in personal and general air samples, and personal welding filter samples were analyzed. Analytical methods included spectroscopy, X-ray diffraction, gravimetry, and chromatography. Quartz (14808607) was detected in settled dust and high volume air samples; beet pulp was considered to be a potential health risk. Exposures in excess of the most stringent environmental criteria were found for calcium-oxide (1305788) in lime kiln workers, formaldehyde (50000) in diffuser area workers, and total welding fumes, nickel (7440020), and iron-oxide (1332372) during welding operations. Exposures to nickel and formaldehyde presented potential cancer risks. Interference prevented analysis of hexavalent chromium (18540299), but the authors expect that it would be elevated. The authors recommend formaldehyde replacement, particulate containment, ventilation improvement, and use of appropriate respiratory protection.","Health Hazard Evaluation Report No. HETA-85-018-1759, American Crystal Sugar Company, Moorhead, Minnesota Abs: A sugar beet mill (SIC-2063) owned by the American Crystal Sugar Company (ACSCO) was evaluated for worker exposure to airborne contaminants during beet processing and welding fumes during facility maintenance, following a request from ACSCO management and the American Federation of Grain Millers International Union. Beet processing involved approximately 690 workers, while maintenance involved approximately 300 of these workers. Total and respirable dusts were measured in personal and general air samples, and personal welding filter samples were analyzed. Analytical methods included spectroscopy, X-ray diffraction, gravimetry, and chromatography. Quartz (14808607) was detected in settled dust and high volume air samples; beet pulp was considered to be a potential health risk. Exposures in excess of the most stringent environmental criteria were found for calcium-oxide (1305788) in lime kiln workers, formaldehyde (50000) in diffuser area workers, and total welding fumes, nickel (7440020), and iron-oxide (1332372) during welding operations. Exposures to nickel and formaldehyde presented potential cancer risks. Interference prevented analysis of hexavalent chromium (18540299), but the authors expect that it would be elevated. The authors recommend formaldehyde replacement, particulate containment, ventilation improvement, and use of appropriate respiratory protection."
1514243,Allan and  Kukacka 1995,Blast furnace slag-modified grouts for in situ stabilization of chromium-contaminated soil,"BIOSIS COPYRIGHT: BIOL ABS. Blast furnace slag-modified grouts were used to stabilize soils contaminated with trivalent and hexavalent chromium. Slag content, grout/soil ratio and water/cementitious material ratio were varied to determine the effects on leachability of chromium, permeability and compressive strength. Slag-modified grouts successfully stabilized Cr(VI)-contaminated soil to give low leachability, thereby allowing omission of the pretreatment stage to reduce CR(VI) to CR(III) necessary with lime and ordinary Portland cement stabilization procedures. Leachability of both CR(III) and CR(VI) decreased with increasing slag content. The permanence of leach resistance is enhanced by higher slag levels in grout. Compressive strength of grout-treated soil ranges from 6 to 36 MPa and permeability is of the order of 10-11 to 10-7 cm/s, depending on mix proportions. Slag-modified grouts have potential for in situ stabilization of Cr(III)- or Cr(VI)-contaminated landfills.","Blast furnace slag-modified grouts for in situ stabilization of chromium-contaminated soil Abs: BIOSIS COPYRIGHT: BIOL ABS. Blast furnace slag-modified grouts were used to stabilize soils contaminated with trivalent and hexavalent chromium. Slag content, grout/soil ratio and water/cementitious material ratio were varied to determine the effects on leachability of chromium, permeability and compressive strength. Slag-modified grouts successfully stabilized Cr(VI)-contaminated soil to give low leachability, thereby allowing omission of the pretreatment stage to reduce CR(VI) to CR(III) necessary with lime and ordinary Portland cement stabilization procedures. Leachability of both CR(III) and CR(VI) decreased with increasing slag content. The permanence of leach resistance is enhanced by higher slag levels in grout. Compressive strength of grout-treated soil ranges from 6 to 36 MPa and permeability is of the order of 10-11 to 10-7 cm/s, depending on mix proportions. Slag-modified grouts have potential for in situ stabilization of Cr(III)- or Cr(VI)-contaminated landfills."
1514242,Al-Akel and  Shamsi 1996,Hexavalent chromium: Toxicity and impact on carbohydrate metabolism and haematological parameters of carp (Cyprinus carpio L.) from Saudi Arabia,"BIOSIS COPYRIGHT: BIOL ABS. The effect of hexavalent chromium on the carp Cyprinus carpio was assessed using static bioassay. The 96 h LC50 was found to be 93.6 mgto sublethal concentrations of chromium (15 and 25 mgignificant depletion of liver and muscle glycogen and decreasing leucocyte counts were recorded during prolonged exposure and with increasing concentration of chromium. The other blood parameters examined (haemoglobin, erythrocyte count, hematocrit, serum protein, serum glucose) increased similarly during exposure to two chromium concentrations.","Hexavalent chromium: Toxicity and impact on carbohydrate metabolism and haematological parameters of carp (Cyprinus carpio L.) from Saudi Arabia Abs: BIOSIS COPYRIGHT: BIOL ABS. The effect of hexavalent chromium on the carp Cyprinus carpio was assessed using static bioassay. The 96 h LC50 was found to be 93.6 mgto sublethal concentrations of chromium (15 and 25 mgignificant depletion of liver and muscle glycogen and decreasing leucocyte counts were recorded during prolonged exposure and with increasing concentration of chromium. The other blood parameters examined (haemoglobin, erythrocyte count, hematocrit, serum protein, serum glucose) increased similarly during exposure to two chromium concentrations."
1514241,Al-Akel 1996,"Chromium toxicity and its impact on behavioral responses in freshwater carp, Cyprinus carpio from Saudi Arabia","BIOSIS COPYRIGHT: BIOL ABS. The effect of hexavalent chromium on the static bioassay on the cyprinid fish, Cyprinus carpio was assessed. The fish exposed to chromium ranging (80-105 mg L-1) for 96 hrs showed LC50 of 93.6 mg L-1. On sub-lethal concentrations (15, 25 and 50 mg L-1) remarkable changes in behaviour such as coughing, yawning, erratic body movement, loss of balance, partial jerks, an increase sojourn to the surface and some aggressive behaviours (nudge and nip) were recorded. These behavioural changes were more pronounced with increasing concentration or chromium.","Chromium toxicity and its impact on behavioral responses in freshwater carp, Cyprinus carpio from Saudi Arabia Abs: BIOSIS COPYRIGHT: BIOL ABS. The effect of hexavalent chromium on the static bioassay on the cyprinid fish, Cyprinus carpio was assessed. The fish exposed to chromium ranging (80-105 mg L-1) for 96 hrs showed LC50 of 93.6 mg L-1. On sub-lethal concentrations (15, 25 and 50 mg L-1) remarkable changes in behaviour such as coughing, yawning, erratic body movement, loss of balance, partial jerks, an increase sojourn to the surface and some aggressive behaviours (nudge and nip) were recorded. These behavioural changes were more pronounced with increasing concentration or chromium."
1514240,Alaerts et al. 1989,Use of coconut shell-based activated carbon for chromium-vi removal,Biosis copyright: biol abs. rrm wastewater treatment ph pollution control,Use of coconut shell-based activated carbon for chromium-vi removal Abs: Biosis copyright: biol abs. rrm wastewater treatment ph pollution control
1514239,Aksu et al. 1996,Investigation of biosorption of chromium (VI) on Cladophora crispata in two-staged batch reactor,"BIOSIS COPYRIGHT: BIOL ABS. In this study, the adsorption of chromium(VI) to C. crispata was investigated in a two-staged batch reactor. The sorption phenomenon was expressed by the Freundlich adsorption isotherm and this expression was used for the calculation of the equilibrium value of the residual or adsorbed chromium(VI) concentration(Ceq or Cxeq) at each stage for a given ""quantity of alga/volume of waste water containing chromium(VI)"" or (Xoo) ratio in a two-staged batch reactor. Experimental Ceq values were compared to calculated ones at each stage. Applications in waste water treatment for chromium(VI) removal have been suggested.","Investigation of biosorption of chromium (VI) on Cladophora crispata in two-staged batch reactor Abs: BIOSIS COPYRIGHT: BIOL ABS. In this study, the adsorption of chromium(VI) to C. crispata was investigated in a two-staged batch reactor. The sorption phenomenon was expressed by the Freundlich adsorption isotherm and this expression was used for the calculation of the equilibrium value of the residual or adsorbed chromium(VI) concentration(Ceq or Cxeq) at each stage for a given ""quantity of alga/volume of waste water containing chromium(VI)"" or (Xoo) ratio in a two-staged batch reactor. Experimental Ceq values were compared to calculated ones at each stage. Applications in waste water treatment for chromium(VI) removal have been suggested."
1514238,Aksu et al. 1991,"Investigation of biosorption of copper(II), nickel(II) and chromium(VI) ions to activated sludge bacteria","BIOSIS COPYRIGHT: BIOL ABS. In this study, the adsorption of Cu(II), Ni(II), and Cr(VI) ions to activated sludge bacteria obtained from the waste water system of METEKSAN, Turkey was investigated. Optimum adsorption temperatures and pH values of each ion were determined as 25ê C, 35ê C, 45ê C, and as pH 5.0, 5.0, and 1.0, respectively. Initial metal ion concentrations of 150-200 ppm gave the highest initial adsorption rates for all metal ions. Corresponding Freundlich adsorption constants and adsorption degrees were found from the Freundlich adsorption isotherms which were constituted at 25ê C.","Investigation of biosorption of copper(II), nickel(II) and chromium(VI) ions to activated sludge bacteria Abs: BIOSIS COPYRIGHT: BIOL ABS. In this study, the adsorption of Cu(II), Ni(II), and Cr(VI) ions to activated sludge bacteria obtained from the waste water system of METEKSAN, Turkey was investigated. Optimum adsorption temperatures and pH values of each ion were determined as 25ê C, 35ê C, 45ê C, and as pH 5.0, 5.0, and 1.0, respectively. Initial metal ion concentrations of 150-200 ppm gave the highest initial adsorption rates for all metal ions. Corresponding Freundlich adsorption constants and adsorption degrees were found from the Freundlich adsorption isotherms which were constituted at 25ê C."
1514237,Aksu et al. 1997,Application of multicomponent adsorption isotherms to simultaneous biosorption of iron(III) and chromium(VI) on C. vulgaris,"BIOSIS COPYRIGHT: BIOL ABS. Although the biosorption of single metal ions to various microorganisms has been extensively studied and adsorption isotherms have been developed for single metal ion situations, very little attention has been given to the bioremoval and the expression of the adsorption isotherms of multi-metal ions systems. In this study, the competitive biosorption of iron(III) and chromium(VI) to Chlorella vulgaris from a binary metal mixture was studied and compared with the single metal ion situation in a batch stirred system. The effects of pH and single and dual metal ion concentrations on the biosorption rates and equilibrium uptakes were investigated. The optimum biosorption pH for both metal ions was determined as 2.0. Multi-metal ion biosorption studies were also performed at this pH value. It was observed that the biosorption rates and yields and equilibrium uptakes of iron(III) or chromium(VI) ions were reduced by the presence of increasing concentrations of the other metal","Application of multicomponent adsorption isotherms to simultaneous biosorption of iron(III) and chromium(VI) on C. vulgaris Abs: BIOSIS COPYRIGHT: BIOL ABS. Although the biosorption of single metal ions to various microorganisms has been extensively studied and adsorption isotherms have been developed for single metal ion situations, very little attention has been given to the bioremoval and the expression of the adsorption isotherms of multi-metal ions systems. In this study, the competitive biosorption of iron(III) and chromium(VI) to Chlorella vulgaris from a binary metal mixture was studied and compared with the single metal ion situation in a batch stirred system. The effects of pH and single and dual metal ion concentrations on the biosorption rates and equilibrium uptakes were investigated. The optimum biosorption pH for both metal ions was determined as 2.0. Multi-metal ion biosorption studies were also performed at this pH value. It was observed that the biosorption rates and yields and equilibrium uptakes of iron(III) or chromium(VI) ions were reduced by the presence of increasing concentrations of the other metal"
1514236,Aide and  Tibbs 1988,Chromium in a sandy soil contaminated by aluminum etching waste fluids,"BIOSIS COPYRIGHT: BIOL ABS. An aluminum window manufacturing plant in Malden, Missouri (USA) contaminated a sandy soil with blue-green Cr-Al coprecipitates from effluent suspensions. A bimodal Cr distribution with peak concentrations at the surface and at approximately 1 m demonstrates Cr mobility in this soil. Elevated Cr at 1 m is associated with increased clay content and Mn(II). Chromium's mobility is attributed to a rapid leaching of chromate at the time of deposition and the possible very slow dissolution of Cr(OH)4-. Significant amounts of chromate were likely reduced to Cr(III) oxyhydroxides because of organic matter oxidation and hydrolysis.","Chromium in a sandy soil contaminated by aluminum etching waste fluids Abs: BIOSIS COPYRIGHT: BIOL ABS. An aluminum window manufacturing plant in Malden, Missouri (USA) contaminated a sandy soil with blue-green Cr-Al coprecipitates from effluent suspensions. A bimodal Cr distribution with peak concentrations at the surface and at approximately 1 m demonstrates Cr mobility in this soil. Elevated Cr at 1 m is associated with increased clay content and Mn(II). Chromium's mobility is attributed to a rapid leaching of chromate at the time of deposition and the possible very slow dissolution of Cr(OH)4-. Significant amounts of chromate were likely reduced to Cr(III) oxyhydroxides because of organic matter oxidation and hydrolysis."
1514235,Aide and  Cummings 1997,The influence of pH and phosphorus on the adsorption of chromium (V) on boehmite,"BIOSIS COPYRIGHT: BIOL ABS. Chromium, particularly Cr(VI), is a potential threat to groundwater supplies because of industrial contamination. Recent research efforts have been focused on describing and simulating Cr(VI) adsorption on a variety of naturally occurring and synthetic substrates, including whole soil, phyllosilicate minerals, and Fe and Al oxides. This investigation describes the influence of Cr(VI) concentration, pH, and o-phosphate concentration on Cr (VI) adsorption on synthetic boehmite. Chromate adsorption isotherms were produced using a batch protocol involving sequences of increasingly concentrated Cr(VI) solutions equilibrated with boehmite. The o-phosphate concentrations (0, 0.13, and 0.25 mmole P L-1) and eight pH levels were discretely varied in the preparation of these Cr(VI) isotherms to assess the influence of these variables on the isotherm's shape. Chromate adsorption was favored in acidic media, whereas o-phosphate suppressed Cr(VI) adsorption. Additionally, the proton","The influence of pH and phosphorus on the adsorption of chromium (V) on boehmite Abs: BIOSIS COPYRIGHT: BIOL ABS. Chromium, particularly Cr(VI), is a potential threat to groundwater supplies because of industrial contamination. Recent research efforts have been focused on describing and simulating Cr(VI) adsorption on a variety of naturally occurring and synthetic substrates, including whole soil, phyllosilicate minerals, and Fe and Al oxides. This investigation describes the influence of Cr(VI) concentration, pH, and o-phosphate concentration on Cr (VI) adsorption on synthetic boehmite. Chromate adsorption isotherms were produced using a batch protocol involving sequences of increasingly concentrated Cr(VI) solutions equilibrated with boehmite. The o-phosphate concentrations (0, 0.13, and 0.25 mmole P L-1) and eight pH levels were discretely varied in the preparation of these Cr(VI) isotherms to assess the influence of these variables on the isotherm's shape. Chromate adsorption was favored in acidic media, whereas o-phosphate suppressed Cr(VI) adsorption. Additionally, the proton"
1514234,Aide 1992,Influence of organic matter and O-phosphate on chromium(VI) adsorption,"BIOSIS COPYRIGHT: BIOL ABS. Recent investigations of the soil chemistry of chromium suggest that chromium may exist in two forms: (1) the chromate anion and (2) the chronic cation. The present study used chromate absorption isotherms on selected horizons from six soils differing in texture. pH, and organic carbon. Generally, higher levels of organic carbon were associated with enhanced chromate adsorptivity, while o-phosphate, as a co-solute, inhibited chromate adsorptivity. Organic carbon was inferred to easily reduce chromate, giving appearances of a high selectivity. Chromate adsorption in organic carbon impoverished horizons is proposed to be a combination of anionic reduction by Fe(II)-Mn(II) and an anionic competitive exchange reaction.","Influence of organic matter and O-phosphate on chromium(VI) adsorption Abs: BIOSIS COPYRIGHT: BIOL ABS. Recent investigations of the soil chemistry of chromium suggest that chromium may exist in two forms: (1) the chromate anion and (2) the chronic cation. The present study used chromate absorption isotherms on selected horizons from six soils differing in texture. pH, and organic carbon. Generally, higher levels of organic carbon were associated with enhanced chromate adsorptivity, while o-phosphate, as a co-solute, inhibited chromate adsorptivity. Organic carbon was inferred to easily reduce chromate, giving appearances of a high selectivity. Chromate adsorption in organic carbon impoverished horizons is proposed to be a combination of anionic reduction by Fe(II)-Mn(II) and an anionic competitive exchange reaction."
1514233,Aide 1993,Chromiumvi adsorption on soils,Biosis copyright: biol abs. rrm research article phosphate chromate aluminum iron toxicity ph,Chromiumvi adsorption on soils Abs: Biosis copyright: biol abs. rrm research article phosphate chromate aluminum iron toxicity ph
1514232,Agrawal et al. 1985,Hematological characteristics of clarias-batrachus under the metallic stress of hexavalent chromium,Biosis copyright: biol abs. rrm toxicity acute anemia,Hematological characteristics of clarias-batrachus under the metallic stress of hexavalent chromium Abs: Biosis copyright: biol abs. rrm toxicity acute anemia
1514231,Adelman et al. 1976,"Acute toxicity of sodium chloride, pentachlorophenol, Guthion, and hexavalent chromium to fathead minnows (Pimephales promelas) and goldfish (Carassius auratus)","PESTAB. The 96-hr LC50s for sodium chloride were 7650 and 7341 mg/l, for pentachlorophenol 0.21 and 0.22 mg/l, for Guthion 1.9 and 2.4 mg/l, and for hexavalent chromium 48 and 120 mg/l, for fathead minnows (Pimephales promelas) and goldfish (Carassius auratus), respectively. Threshold LD50s were reached in 6 days for sodium chloride (7650 and 7322 mg/l for fathead minnows and goldfish, respectively), and pentachlorophenol (0.21 and 0.21 mg/l), but were not attained in 11 days (termination of testing) with Guthion (0.76 and 0.80 mg/l) and hexavalent chromium (18 and 33 mg/l). With pentachlorphenol and Guthion goldfish were initially more resistant, but by termination there was no significant difference in LD50s between the two species. With hexavalent chromium the goldfish were more resistant throughout the 11-day test, and with sodium chloride goldfish were initially more resistant but at attainment of a threshold LC50 were less resistant. Use of toxicity curves for assessment of acute mortality permits interpretation not possible in 96-hr tests where LC50s are computed at 24-hr intervals. (Author abstract by permission)","Acute toxicity of sodium chloride, pentachlorophenol, Guthion, and hexavalent chromium to fathead minnows (Pimephales promelas) and goldfish (Carassius auratus) Abs: PESTAB. The 96-hr LC50s for sodium chloride were 7650 and 7341 mg/l, for pentachlorophenol 0.21 and 0.22 mg/l, for Guthion 1.9 and 2.4 mg/l, and for hexavalent chromium 48 and 120 mg/l, for fathead minnows (Pimephales promelas) and goldfish (Carassius auratus), respectively. Threshold LD50s were reached in 6 days for sodium chloride (7650 and 7322 mg/l for fathead minnows and goldfish, respectively), and pentachlorophenol (0.21 and 0.21 mg/l), but were not attained in 11 days (termination of testing) with Guthion (0.76 and 0.80 mg/l) and hexavalent chromium (18 and 33 mg/l). With pentachlorphenol and Guthion goldfish were initially more resistant, but by termination there was no significant difference in LD50s between the two species. With hexavalent chromium the goldfish were more resistant throughout the 11-day test, and with sodium chloride goldfish were initially more resistant but at attainment of a threshold LC50 were less resistant. Use of toxicity curves for assessment of acute mortality permits interpretation not possible in 96-hr tests where LC50s are computed at 24-hr intervals. (Author abstract by permission)"
1514230,Abbasi and  Soni 1983,Stress-induced enhancement of reproduction in earthworm Octochaetus pattoni exposed to chromium (VI) and mercury (II): Implications in environmental management,"HEEP COPYRIGHT: BIOL ABS. The impact of heavy metal pollutants on earthworms was studied by observing mortality and reproduction in O. pattoni exposed to Cr (VI) and Hg (II) at levels varying from 0-25 ppm. While both metals induced significant mortality at all levels of exposure, they also caused an enhancement in reproduction, as revealed by the higher production of juveniles and bits in metal-exposed animals compared to controls. The significance of the results in environmental management was discussed.","Stress-induced enhancement of reproduction in earthworm Octochaetus pattoni exposed to chromium (VI) and mercury (II): Implications in environmental management Abs: HEEP COPYRIGHT: BIOL ABS. The impact of heavy metal pollutants on earthworms was studied by observing mortality and reproduction in O. pattoni exposed to Cr (VI) and Hg (II) at levels varying from 0-25 ppm. While both metals induced significant mortality at all levels of exposure, they also caused an enhancement in reproduction, as revealed by the higher production of juveniles and bits in metal-exposed animals compared to controls. The significance of the results in environmental management was discussed."
1510705,Walsh and  Ohalloran 1997,The toxicity of leather tannery effluent to a population of the blue mussel Mytilus edulis (L),,The toxicity of leather tannery effluent to a population of the blue mussel Mytilus edulis (L) Abs: 
1510704,Rodriguez et al. 1997,Metal ion-dependent hydrogen peroxide-induced DNA damage is more sequence specific than metal specific,,Metal ion-dependent hydrogen peroxide-induced DNA damage is more sequence specific than metal specific Abs: 
1510702,Farre et al. 1997,Application of capillary electrophoresis in the quality control of osmotically treated water,,Application of capillary electrophoresis in the quality control of osmotically treated water Abs: 
1510700,Mattagajasingh and  Misra 1997,Carcinogenic chromium(VI) induces oxidative stress in cultured human leukemic T-lymphocytes. 1. Generation of hydrogen peroxide during intracellular reduction of chromate,"Treatment of human leukemic T-lymphocyte MOLT4 cells with potassium chromate, a chromium(VI) compound, increased the formation, of the oxidized compound dichlorofluorescein (DCF), a highly fluorescent compound from the parent nonfluorescent compound, 2,7-dichlorofluorescin diacetate (DCF-DA). No such increase in DCF formation was observed when cells were treated with Cr(III) compounds. In cell-free systems, dichlorofluorescin diacetate was also oxidized to DCF by strong oxidants (such as hydrogen peroxide and hydroperoxides) in the presence of peroxidase, suggesting that Cr(VI) treatment increased the intracellular level of these peroxides in MOLT4 cells. The rate of generation of peroxides was found to be both dose and time dependent. These results suggest that accumulation of intracellular peroxides may, at least in part, be associated with chromium-induced genotoxicity and add to the emerging concept that these phenomena may, in part, be mediated via oxidative mechanisms.","Carcinogenic chromium(VI) induces oxidative stress in cultured human leukemic T-lymphocytes. 1. Generation of hydrogen peroxide during intracellular reduction of chromate Abs: Treatment of human leukemic T-lymphocyte MOLT4 cells with potassium chromate, a chromium(VI) compound, increased the formation, of the oxidized compound dichlorofluorescein (DCF), a highly fluorescent compound from the parent nonfluorescent compound, 2,7-dichlorofluorescin diacetate (DCF-DA). No such increase in DCF formation was observed when cells were treated with Cr(III) compounds. In cell-free systems, dichlorofluorescin diacetate was also oxidized to DCF by strong oxidants (such as hydrogen peroxide and hydroperoxides) in the presence of peroxidase, suggesting that Cr(VI) treatment increased the intracellular level of these peroxides in MOLT4 cells. The rate of generation of peroxides was found to be both dose and time dependent. These results suggest that accumulation of intracellular peroxides may, at least in part, be associated with chromium-induced genotoxicity and add to the emerging concept that these phenomena may, in part, be mediated via oxidative mechanisms."
1510699,Sobti et al. 1997,Studies on the rec effects of chromium(VI) compounds in Bacillus subtilis,,Studies on the rec effects of chromium(VI) compounds in Bacillus subtilis Abs: 
1510697,Tsu and  Yang 1996,Formation of reactive oxygen species and DNA strand breakage during interaction of chromium(III) and hydrogen peroxide in vitro: Evidence for a chromium(III)-mediated Fenton-like reaction,,Formation of reactive oxygen species and DNA strand breakage during interaction of chromium(III) and hydrogen peroxide in vitro: Evidence for a chromium(III)-mediated Fenton-like reaction Abs: 
1510695,Zhitkovich et al. 1996,DNA-protein crosslinks in peripheral lymphocytes of individuals exposed to hexavalent chromium compounds,"Abstract DNA-protein crosslinks were measured in peripheral blood lymphocytes of chrome-platers and controls from Bulgaria in order to evaluate a genotoxic effect of human exposure to carcinogenic Cr(VI) compounds. Chrome-platers and most of the unexposed controls were from the industrial city of Jambol; some additional controls were recruited from the seaside town of Burgas. The chrome-platers had significantly elevated levels of chromium in pre- and post-shift urine, erythrocytes and lymphocytes compared with the control subjects. The largest differences between the two groups were found in erythrocyte chromium concentrations which are considered to be indicative of Cr(VI) exposure. Despite the significant differences in internal chromium doses, levels of DNA-protein crosslinks were not significantly different between the combined controls and exposed workers. Individual DNA-protein crosslinks, however, correlated strongly with chromium in erythrocytes at low and moderate doses but at high exposures, such as among the majority of chrome-platers, these DNA adducts were saturated at maximum levels. The saturation of DNA-protein crosslinks seems to occur at 7-8 ?g I-(1) chromium in erythrocytes whereas a mean erythrocyte chromium among the chrome platers was as high as 22.8 ?g l(-1). Occupationally unexposed subjects exhibited a significant variability with respect to the erythrocyte chromium concentration, however erythrocyte chromium levels correlated closely with DNA-protein crosslinks in lymphocytes. The controls from Jambol had higher chromium concentrations in erythrocytes and elevated levels of DNA-protein crosslinks compared with Burgas controls. Occupational exposure to formaldehyde among furniture factory workers did not change levels of DNA-protein crosslinks in peripheral lymphocytes. DNA-protein crosslink measurements showed a low intraindividual variability and their levels among both controls and exposed indivduals were not affected by smoking, age or weight.","DNA-protein crosslinks in peripheral lymphocytes of individuals exposed to hexavalent chromium compounds Abs: Abstract DNA-protein crosslinks were measured in peripheral blood lymphocytes of chrome-platers and controls from Bulgaria in order to evaluate a genotoxic effect of human exposure to carcinogenic Cr(VI) compounds. Chrome-platers and most of the unexposed controls were from the industrial city of Jambol; some additional controls were recruited from the seaside town of Burgas. The chrome-platers had significantly elevated levels of chromium in pre- and post-shift urine, erythrocytes and lymphocytes compared with the control subjects. The largest differences between the two groups were found in erythrocyte chromium concentrations which are considered to be indicative of Cr(VI) exposure. Despite the significant differences in internal chromium doses, levels of DNA-protein crosslinks were not significantly different between the combined controls and exposed workers. Individual DNA-protein crosslinks, however, correlated strongly with chromium in erythrocytes at low and moderate doses but at high exposures, such as among the majority of chrome-platers, these DNA adducts were saturated at maximum levels. The saturation of DNA-protein crosslinks seems to occur at 7-8 ?g I-(1) chromium in erythrocytes whereas a mean erythrocyte chromium among the chrome platers was as high as 22.8 ?g l(-1). Occupationally unexposed subjects exhibited a significant variability with respect to the erythrocyte chromium concentration, however erythrocyte chromium levels correlated closely with DNA-protein crosslinks in lymphocytes. The controls from Jambol had higher chromium concentrations in erythrocytes and elevated levels of DNA-protein crosslinks compared with Burgas controls. Occupational exposure to formaldehyde among furniture factory workers did not change levels of DNA-protein crosslinks in peripheral lymphocytes. DNA-protein crosslink measurements showed a low intraindividual variability and their levels among both controls and exposed indivduals were not affected by smoking, age or weight."
1510694,Morris et al. 1996,"Chromium picolinate supplementation improves cardiac metabolism, but not myosin isoenzyme distribution in the diabetic heart","Because chromium (Cr) containing compounds are thought to improve glucose homeostasis, we hypothesized that chromium picolinate (CrP) could partially reverse diabetes-induced damage to cardiac tissue. Young, adult female rats were fed either a basal diet (CONT), a basal diet containing no CrP and made diabetic (DIAB-CONT) or a basal diet containing 600 ng/g of CrP (3 times the suggested daily chromium intake) and made diabetic (DIAB-CrP). Diabetes was induced by a single streptozotocin injection, 55 mg/kg i.p. After 8 weeks animals were sacrificed, hearts removed, and spectrophotometrically analyzed for citrate synthase (CS), hexokinase (HK), and beta hydroxyacyl CoA dehydrogenase activity (HOAD). Cardiac myosin isoenzymes were separated from crude myofibril extracts by PAGE electrophoresis. Diabetes did not alter CS activity relative to the CONT group, but did significantly (P < 0.05) reduce HK and HOAD activity and expression of the high ATPase myosin isoenzyme VI. In contrast, DIAB-CrP animals displayed normal HK activity and greater HOAD activity relative to CONT animals. Surprisingly, the addition of CrP to the diet further reduced expression of the VI myosin isoenzyme. These results demonstrate that dietary CrP supplementation has diverse effects on the subcellular properties of the diabetic heart. The functional impact of these CrP-induced changes remains to be defined.","Chromium picolinate supplementation improves cardiac metabolism, but not myosin isoenzyme distribution in the diabetic heart Abs: Because chromium (Cr) containing compounds are thought to improve glucose homeostasis, we hypothesized that chromium picolinate (CrP) could partially reverse diabetes-induced damage to cardiac tissue. Young, adult female rats were fed either a basal diet (CONT), a basal diet containing no CrP and made diabetic (DIAB-CONT) or a basal diet containing 600 ng/g of CrP (3 times the suggested daily chromium intake) and made diabetic (DIAB-CrP). Diabetes was induced by a single streptozotocin injection, 55 mg/kg i.p. After 8 weeks animals were sacrificed, hearts removed, and spectrophotometrically analyzed for citrate synthase (CS), hexokinase (HK), and beta hydroxyacyl CoA dehydrogenase activity (HOAD). Cardiac myosin isoenzymes were separated from crude myofibril extracts by PAGE electrophoresis. Diabetes did not alter CS activity relative to the CONT group, but did significantly (P < 0.05) reduce HK and HOAD activity and expression of the high ATPase myosin isoenzyme VI. In contrast, DIAB-CrP animals displayed normal HK activity and greater HOAD activity relative to CONT animals. Surprisingly, the addition of CrP to the diet further reduced expression of the VI myosin isoenzyme. These results demonstrate that dietary CrP supplementation has diverse effects on the subcellular properties of the diabetic heart. The functional impact of these CrP-induced changes remains to be defined."
1510693,Pantsarkallio and  Manninen 1996,Speciation of chromium in waste waters by coupled column ion chromatography inductively coupled plasma mass spectrometry,,Speciation of chromium in waste waters by coupled column ion chromatography inductively coupled plasma mass spectrometry Abs: 
1510692,Sag and  Kutsal 1996,Fully competitive biosorption of chromium(VI) and iron(III) ions from binary metal mixtures by R-arrhizus: Use of the competitive Langmuir model,,Fully competitive biosorption of chromium(VI) and iron(III) ions from binary metal mixtures by R-arrhizus: Use of the competitive Langmuir model Abs: 
1510689,Horka et al. 1996,Analyte preconcentration procedure based on parallel-current open-tubular liquid chromatography,,Analyte preconcentration procedure based on parallel-current open-tubular liquid chromatography Abs: 
1510688,Abraham and  Graf 1996,Protection by coffee against somatic genotoxicity in Drosophila: Role of bioactivation capacity,,Protection by coffee against somatic genotoxicity in Drosophila: Role of bioactivation capacity Abs: 
1510687,Mao et al. 1996,Generation of reactive oxygen species by Co(II) from H2O2 in the presence of chelators in relation to DNA damage and 2'-deoxyguanosine hydroxylation,,Generation of reactive oxygen species by Co(II) from H2O2 in the presence of chelators in relation to DNA damage and 2'-deoxyguanosine hydroxylation Abs: 
1510686,Sharma and  Forster 1996,A comparison of the sorbtive characteristics of leaf mould and activated carbon columns for the removal of hexavalent chromium,,A comparison of the sorbtive characteristics of leaf mould and activated carbon columns for the removal of hexavalent chromium Abs: 
1510685,Mao et al. 1995,Generation of free radicals by Cr(IV) from lipid hydroperoxides and its inhibition by chelators,"The generation of free radicals by Cr(IV) from lipid hydroperoxides was investigated by ESR spin trapping. The spin trap used was 5,5-dimethyl-1-pyrroline N-oxide (DMPO). Reaction of Cr(VI) with ascorbate was used as a source of Cr(IV). Incubation of Cr(VI) with ascorbate generated Cr(IV) and Cr(V). Addition of cumene hydroperoxide generated DMPO/R adduct with an enhancement of Cr(V) signal. Addition of Mn(II), whose function is to remove Cr(IV), caused dose-dependent inhibition of DMPO/R formation. Similar results were obtained using t-butyl hydroperoxide. Metal ion chelators, deferoxamine, 1,10-phenanthroline and diethylenetriaminepentaacetic acid inhibited DMPO/R formation in the order of deferoxamine > 1,10-phenanthroline > diethylenetriaminepentaacetic acid. The results suggest the possible role of Cr(IV) and its mediated free radical generation from lipid hydroperoxides in the mechanism of Cr(VI) carcinogenesis.","Generation of free radicals by Cr(IV) from lipid hydroperoxides and its inhibition by chelators Abs: The generation of free radicals by Cr(IV) from lipid hydroperoxides was investigated by ESR spin trapping. The spin trap used was 5,5-dimethyl-1-pyrroline N-oxide (DMPO). Reaction of Cr(VI) with ascorbate was used as a source of Cr(IV). Incubation of Cr(VI) with ascorbate generated Cr(IV) and Cr(V). Addition of cumene hydroperoxide generated DMPO/R adduct with an enhancement of Cr(V) signal. Addition of Mn(II), whose function is to remove Cr(IV), caused dose-dependent inhibition of DMPO/R formation. Similar results were obtained using t-butyl hydroperoxide. Metal ion chelators, deferoxamine, 1,10-phenanthroline and diethylenetriaminepentaacetic acid inhibited DMPO/R formation in the order of deferoxamine > 1,10-phenanthroline > diethylenetriaminepentaacetic acid. The results suggest the possible role of Cr(IV) and its mediated free radical generation from lipid hydroperoxides in the mechanism of Cr(VI) carcinogenesis."
1510683,Stearns et al. 1995,Chromium(III) picolinate produces chromosome damage in Chinese hamster ovary cells,"Chromium(III) complexes currently being sold as dietary supplements were tested for their ability to cause chromosomal aberrations in Chinese hamster ovary cells. Complexes were tested in soluble and particulate forms. Chromium picolinate was found to produce chromosome damage 3-fold to 18-fold above control levels for soluble doses of 0.050, 0.10, 0.50, and 1.0 mM after 24 h treatment. Particulate chromium picolinate doses of 8.0 micrograms/cm2 (corresponding to a 0.10 mM solublized dose) and 40 micrograms/cm2 (0.50 mM) produced aberrations 4-fold and 16-fold above control levels, respectively. Toxicity was measured as a decrease in plating efficiency relative to controls. The above treatments produced > or = 86% survival for all doses except 1.0 mM chromium picolinate, which produced 69 +/- 10% survival. Chromium nicotinate, nicotinic acid, and chromium(III) chloride hexahydrate did not produce chromosome damage at equivalent nontoxic doses. Damage was inferred to be caused by the picolinate ligand because picolinic acid in the absence of chromium was clastogenic. Data are evaluated in terms of their relevance to human exposure based on pharmacokinetic modeling of tissue accumulation and are discussed in terms of literature reporting toxic effects of picolinic acid.","Chromium(III) picolinate produces chromosome damage in Chinese hamster ovary cells Abs: Chromium(III) complexes currently being sold as dietary supplements were tested for their ability to cause chromosomal aberrations in Chinese hamster ovary cells. Complexes were tested in soluble and particulate forms. Chromium picolinate was found to produce chromosome damage 3-fold to 18-fold above control levels for soluble doses of 0.050, 0.10, 0.50, and 1.0 mM after 24 h treatment. Particulate chromium picolinate doses of 8.0 micrograms/cm2 (corresponding to a 0.10 mM solublized dose) and 40 micrograms/cm2 (0.50 mM) produced aberrations 4-fold and 16-fold above control levels, respectively. Toxicity was measured as a decrease in plating efficiency relative to controls. The above treatments produced > or = 86% survival for all doses except 1.0 mM chromium picolinate, which produced 69 +/- 10% survival. Chromium nicotinate, nicotinic acid, and chromium(III) chloride hexahydrate did not produce chromosome damage at equivalent nontoxic doses. Damage was inferred to be caused by the picolinate ligand because picolinic acid in the absence of chromium was clastogenic. Data are evaluated in terms of their relevance to human exposure based on pharmacokinetic modeling of tissue accumulation and are discussed in terms of literature reporting toxic effects of picolinic acid."
1510682,Sharma et al. 1995,CHROMIUM ACCUMULATION AND ITS EFFECTS ON WHEAT (TRITICUM-AESTIVUM L CV HD-2204) METABOLISM,,CHROMIUM ACCUMULATION AND ITS EFFECTS ON WHEAT (TRITICUM-AESTIVUM L CV HD-2204) METABOLISM Abs: 
1510679,Ladics et al. 1995,COMPARISON OF 125-IODODEOXYURIDINE ((125)IUDR) AND [H-3] THYMIDINE ([H-3]TDR) FOR ASSESSING CELL-PROLIFERATION IN THE MURINE LOCAL LYMPH-NODE ASSAY,,COMPARISON OF 125-IODODEOXYURIDINE ((125)IUDR) AND [H-3] THYMIDINE ([H-3]TDR) FOR ASSESSING CELL-PROLIFERATION IN THE MURINE LOCAL LYMPH-NODE ASSAY Abs: 
1510678,Nussey et al. 1995,"EFFECT OF COPPER ON THE HEMATOLOGY AND OSMOREGULATION OF THE MOZAMBIQUE TILAPIA, OREOCHROMIS-MOSSAMBICUS (CICHLIDAE)",,"EFFECT OF COPPER ON THE HEMATOLOGY AND OSMOREGULATION OF THE MOZAMBIQUE TILAPIA, OREOCHROMIS-MOSSAMBICUS (CICHLIDAE) Abs: "
1510676,Masnado et al. 1995,"COMPARATIVE ACUTE TOXICITY OF A SYNTHETIC MINE EFFLUENT TO CERIODAPHNIA-DUBIA, LARVAL FATHEAD MINNOW AND THE FRESH-WATER MUSSEL ANODONTA-IMBECILIS","BIOSIS COPYRIGHT: BIOL ABS. To determine if water quality-based effluent limitations recommended for a proposed discharger would provide adequate protection of aquatic life, site-specific acute toxicity tests were performed. The proposed discharger studied was a mine to be located in northern Wisconsin. The mine's discharge would flow into the Flambeau River, a relatively pristine river that harbors endangered freshwater mussels. The toxicity effects of synthetic effluents, representing a mixture of five different metals under contrasting conditions of hardness, were tested on several different organisms. Results indicated that Ceriodaphnia dubia exhibited a much greater sensitivity to various mixtures of cadmium, hexavalent chromium, copper, nickel, and zinc than did either larval fathead minnows (Pimephales promelas) or the freshwater mussel Anodonta imbecilis. Mixtures of metals at the permitted discharge levels of individual metals were also found to be consistently toxic to C. dubia. Because","COMPARATIVE ACUTE TOXICITY OF A SYNTHETIC MINE EFFLUENT TO CERIODAPHNIA-DUBIA, LARVAL FATHEAD MINNOW AND THE FRESH-WATER MUSSEL ANODONTA-IMBECILIS Abs: BIOSIS COPYRIGHT: BIOL ABS. To determine if water quality-based effluent limitations recommended for a proposed discharger would provide adequate protection of aquatic life, site-specific acute toxicity tests were performed. The proposed discharger studied was a mine to be located in northern Wisconsin. The mine's discharge would flow into the Flambeau River, a relatively pristine river that harbors endangered freshwater mussels. The toxicity effects of synthetic effluents, representing a mixture of five different metals under contrasting conditions of hardness, were tested on several different organisms. Results indicated that Ceriodaphnia dubia exhibited a much greater sensitivity to various mixtures of cadmium, hexavalent chromium, copper, nickel, and zinc than did either larval fathead minnows (Pimephales promelas) or the freshwater mussel Anodonta imbecilis. Mixtures of metals at the permitted discharge levels of individual metals were also found to be consistently toxic to C. dubia. Because"
1510675,Corradi et al. 1995,CHROMIUM-INDUCED SEXUAL REPRODUCTION GIVES RISE TO A CR-TOLERANT PROGENY IN SCENEDESMUS-ACUTUS,"A clonal population of Scenedesmus acutus was treated for 3 months with 1 mg/liter Cr(VI) and then returned to Cr-free medium. After several months, the cells were treated with different Cr concentrations and then subjected to a series of morphological observations and metabolic tests. The results, compared with those obtained with a normal cell population treated in the same way, demonstrate that the progeny of algae subjected to the prolonged Cr treatment has acquired tolerance to the metal, as it can survive and grow in the presence of Cr concentrations that are lethal to normal cells. An ultrastructural description of gametes and zygotes is also given.","CHROMIUM-INDUCED SEXUAL REPRODUCTION GIVES RISE TO A CR-TOLERANT PROGENY IN SCENEDESMUS-ACUTUS Abs: A clonal population of Scenedesmus acutus was treated for 3 months with 1 mg/liter Cr(VI) and then returned to Cr-free medium. After several months, the cells were treated with different Cr concentrations and then subjected to a series of morphological observations and metabolic tests. The results, compared with those obtained with a normal cell population treated in the same way, demonstrate that the progeny of algae subjected to the prolonged Cr treatment has acquired tolerance to the metal, as it can survive and grow in the presence of Cr concentrations that are lethal to normal cells. An ultrastructural description of gametes and zygotes is also given."
1510674,Byrdy et al. 1995,CHROMIUM SPECIATION BY ANION-EXCHANGE HIGH-PERFORMANCE LIQUID-CHROMATOGRAPHY WITH BOTH INDUCTIVELY-COUPLED PLASMA-ATOMIC EMISSION SPECTROSCOPIC AND INDUCTIVELY-COUPLED PLASMA-MASS SPECTROMETRIC DETECTION,,CHROMIUM SPECIATION BY ANION-EXCHANGE HIGH-PERFORMANCE LIQUID-CHROMATOGRAPHY WITH BOTH INDUCTIVELY-COUPLED PLASMA-ATOMIC EMISSION SPECTROSCOPIC AND INDUCTIVELY-COUPLED PLASMA-MASS SPECTROMETRIC DETECTION Abs: 
1510672,Eriksen et al. 1995,MECHANISM OF METAL-ION CATALYZED CARBOHYDRATE TRANSFORMATIONS - STOICHIOMETRY OF ALDOPENTOSE REARRANGEMENT PROCESSES CATALYZED BY A MACROCYCLIC CHROMIUM(III) COMPLEX,,MECHANISM OF METAL-ION CATALYZED CARBOHYDRATE TRANSFORMATIONS - STOICHIOMETRY OF ALDOPENTOSE REARRANGEMENT PROCESSES CATALYZED BY A MACROCYCLIC CHROMIUM(III) COMPLEX Abs: 
1510670,Fresco et al. 1995,THE REDUCTIVE CONVERSION OF CHROMIUM(VI) BY ASCORBATE GIVES RISE TO APURINIC APYRIMIDINIC SITES IN ISOLATED DNA,,THE REDUCTIVE CONVERSION OF CHROMIUM(VI) BY ASCORBATE GIVES RISE TO APURINIC APYRIMIDINIC SITES IN ISOLATED DNA Abs: 
1510667,Inoue et al. 1995,SIMULTANEOUS DETERMINATION OF CHROMIUM(III) AND CHROMIUM(VI) BY ION CHROMATOGRAPHY WITH INDUCTIVELY-COUPLED PLASMA-MASS SPECTROMETRY,BIOSIS COPYRIGHT: BIOL ABS. RRM RESEARCH ARTICLE ENVIRONMENTAL CONTAMINANT WATER MAGNESIUM CALCIUM MANGANESE IRON COBALT NICKEL COPPER ZINC LEAD CALCIUM CARBONATE ANION-EXCHANGE CHROMATOGRAPHY PURIFICATION METHOD ANALYTICAL METHOD,SIMULTANEOUS DETERMINATION OF CHROMIUM(III) AND CHROMIUM(VI) BY ION CHROMATOGRAPHY WITH INDUCTIVELY-COUPLED PLASMA-MASS SPECTROMETRY Abs: BIOSIS COPYRIGHT: BIOL ABS. RRM RESEARCH ARTICLE ENVIRONMENTAL CONTAMINANT WATER MAGNESIUM CALCIUM MANGANESE IRON COBALT NICKEL COPPER ZINC LEAD CALCIUM CARBONATE ANION-EXCHANGE CHROMATOGRAPHY PURIFICATION METHOD ANALYTICAL METHOD
1510665,Chassardbouchaud et al. 1995,"CELLULAR AND SUBCELLULAR-LOCALIZATION OF CHROMIUM IN THE CRAB LIOCARCINUS PUBER (BRACHYRHYNCHA) BY TRANSMISSION ELECTRON-MICROSCOPY, SECONDARY-ION MASS-SPECTROMETRY AND ELECTRON-MICROPROBE ANALYSIS",,"CELLULAR AND SUBCELLULAR-LOCALIZATION OF CHROMIUM IN THE CRAB LIOCARCINUS PUBER (BRACHYRHYNCHA) BY TRANSMISSION ELECTRON-MICROSCOPY, SECONDARY-ION MASS-SPECTROMETRY AND ELECTRON-MICROPROBE ANALYSIS Abs: "
1510662,Pillichshammer et al. 1995,BIOSORPTION OF CHROMIUM TO FUNGI,,BIOSORPTION OF CHROMIUM TO FUNGI Abs: 
1510661,Pepi and  Baldi 1995,CHROMATE TOLERANCE IN STRAINS OF RHODOSPORIDIUM TORULOIDES MODULATED BY THIOSULFATE AND SULFUR AMINO-ACIDS,,CHROMATE TOLERANCE IN STRAINS OF RHODOSPORIDIUM TORULOIDES MODULATED BY THIOSULFATE AND SULFUR AMINO-ACIDS Abs: 
1510660,Pickering and  Lazorchak 1995,"EVALUATION OF THE ROBUSTNESS OF THE FATHEAD MINNOW, PIMEPHALES-PROMELAS, LARVAL SURVIVAL AND GROWTH TEST, US EPA METHOD-1000.0",,"EVALUATION OF THE ROBUSTNESS OF THE FATHEAD MINNOW, PIMEPHALES-PROMELAS, LARVAL SURVIVAL AND GROWTH TEST, US EPA METHOD-1000.0 Abs: "
1510657,Rizzotto et al. 1995,CHROMIC OXIDATION OF 2-DEOXY-D-GLUCOSE - COMPARATIVE-STUDY WITH ALDOSES .1,,CHROMIC OXIDATION OF 2-DEOXY-D-GLUCOSE - COMPARATIVE-STUDY WITH ALDOSES .1 Abs: 
1510656,Bandwar et al. 1995,"TRANSITION-METAL SACCHARIDE CHEMISTRY - D-GLUCOSE COMPLEXES OF MN(II), CO(II), NI(II), CU(II) AND ZN(II)",,"TRANSITION-METAL SACCHARIDE CHEMISTRY - D-GLUCOSE COMPLEXES OF MN(II), CO(II), NI(II), CU(II) AND ZN(II) Abs: "
1510655,Garcia et al. 1994,THE ENVIRONMENTAL-IMPACT OF CHROMIUM SALTS - ECOTOXICITY AND INHIBITION OF SURFACTANT BIODEGRADATION,,THE ENVIRONMENTAL-IMPACT OF CHROMIUM SALTS - ECOTOXICITY AND INHIBITION OF SURFACTANT BIODEGRADATION Abs: 
1510654,Spini et al. 1994,"DETERMINATION OF HEXAVALENT, TRIVALENT AND METALLIC CHROMIUM IN WELDING FUMES",,"DETERMINATION OF HEXAVALENT, TRIVALENT AND METALLIC CHROMIUM IN WELDING FUMES Abs: "
1510653,Berg 1994,"SYMBIOTIC VESICLE ULTRASTRUCTURE IN HIGH PRESSURE-FROZEN, FREEZE-SUBSTITUTED ACTINORHIZAE",,"SYMBIOTIC VESICLE ULTRASTRUCTURE IN HIGH PRESSURE-FROZEN, FREEZE-SUBSTITUTED ACTINORHIZAE Abs: "
1510651,Karlsen et al. 1994,EXPOSURE TO SOLID AEROSOLS DURING REGULAR MMA WELDING AND GRINDING OPERATIONS ON STAINLESS-STEEL,"Air concentrations of solid aerosols were measured during manual metal arc welding (MMA) on stainless steel at three worksites. Mean fume concentrations were 5.4mg/m|3| inside a ship section, 3.0mg/m|3| in a module for water injection into offshore oil wells, and 2.0mg/m|3| in welding shops. The highest concentrations of hexavalent chromium were found inside the ship section. Although the base material contained approximately 20% chromium and 10% nickel, the contents of these metals varied greatly among the different sites. Grinding generated a mean concentration of 11mg/m|3|, of which chromium was about 10% of the total solid aerosol.","EXPOSURE TO SOLID AEROSOLS DURING REGULAR MMA WELDING AND GRINDING OPERATIONS ON STAINLESS-STEEL Abs: Air concentrations of solid aerosols were measured during manual metal arc welding (MMA) on stainless steel at three worksites. Mean fume concentrations were 5.4mg/m|3| inside a ship section, 3.0mg/m|3| in a module for water injection into offshore oil wells, and 2.0mg/m|3| in welding shops. The highest concentrations of hexavalent chromium were found inside the ship section. Although the base material contained approximately 20% chromium and 10% nickel, the contents of these metals varied greatly among the different sites. Grinding generated a mean concentration of 11mg/m|3|, of which chromium was about 10% of the total solid aerosol."
1510650,Vanvuren et al. 1994,THE EFFECT OF COPPER ON THE BLOOD-CHEMISTRY OF CLARIAS-GARIEPINUS (CLARIIDAE),,THE EFFECT OF COPPER ON THE BLOOD-CHEMISTRY OF CLARIAS-GARIEPINUS (CLARIIDAE) Abs: 
1510647,Prokisch et al. 1994,INTERFACING ION CHROMATOGRAPHY WITH INDUCTIVELY-COUPLED PLASMA-ATOMIC EMISSION-SPECTROMETRY FOR THE DETERMINATION OF CHROMIUM(III) AND CHROMIUM(VI),,INTERFACING ION CHROMATOGRAPHY WITH INDUCTIVELY-COUPLED PLASMA-ATOMIC EMISSION-SPECTROMETRY FOR THE DETERMINATION OF CHROMIUM(III) AND CHROMIUM(VI) Abs: 
1510646,Hutchinson et al. 1994,"TOXICITY OF CADMIUM, HEXAVALENT CHROMIUM AND COPPER TO MARINE FISH LARVAE (CYPRINODON-VARIEGATUS) AND COPEPODS (TISBE BATTAGLIAI)",,"TOXICITY OF CADMIUM, HEXAVALENT CHROMIUM AND COPPER TO MARINE FISH LARVAE (CYPRINODON-VARIEGATUS) AND COPEPODS (TISBE BATTAGLIAI) Abs: "
1510645,Losi et al. 1994,FACTORS AFFECTING CHEMICAL AND BIOLOGICAL REDUCTION OF HEXAVALENT CHROMIUM IN SOIL,,FACTORS AFFECTING CHEMICAL AND BIOLOGICAL REDUCTION OF HEXAVALENT CHROMIUM IN SOIL Abs: 
1510644,Sousa and  Oliveira 1994,"AN ULTRASTRUCTURAL-STUDY OF SPERMATOGENESIS IN HELCION PELLUCIDUS (GASTROPODA, PROSOBRANCHIA)",,"AN ULTRASTRUCTURAL-STUDY OF SPERMATOGENESIS IN HELCION PELLUCIDUS (GASTROPODA, PROSOBRANCHIA) Abs: "
1510636,Srivastava et al. 1994,STUDIES ON THE UPTAKE OF TRIVALENT AND HEXAVALENT CHROMIUM BY ONION (ALLIUM-CEPA),,STUDIES ON THE UPTAKE OF TRIVALENT AND HEXAVALENT CHROMIUM BY ONION (ALLIUM-CEPA) Abs: 
1510633,Gopalan and  Veeramani 1994,DEVELOPMENT OF A PSEUDOMONAS-SP FOR AEROBIC CHROMATE REDUCTION,,DEVELOPMENT OF A PSEUDOMONAS-SP FOR AEROBIC CHROMATE REDUCTION Abs: 
1510630,Narra et al. 1994,AUGER-ELECTRON EMITTERS AS TOOLS FOR ELUCIDATING THE LOCATION OF PRIMARY RADIOSENSITIVE TARGETS,,AUGER-ELECTRON EMITTERS AS TOOLS FOR ELUCIDATING THE LOCATION OF PRIMARY RADIOSENSITIVE TARGETS Abs: 
1510628,Gue et al. 1994,CENTRAL CCK-8S RECEPTORS TRIGGER THE SIGMA LIGAND-INDUCED AND 5-HT(1A) AGONISTS-INDUCED ACCELERATION OF POSTPRANDIAL COLONIC TRANSIT IN RATS,,CENTRAL CCK-8S RECEPTORS TRIGGER THE SIGMA LIGAND-INDUCED AND 5-HT(1A) AGONISTS-INDUCED ACCELERATION OF POSTPRANDIAL COLONIC TRANSIT IN RATS Abs: 
1510625,Viana et al. 1993,CLEANUP AND CONFIRMATION PROCEDURES FOR GAS-CHROMATOGRAPHIC DETERMINATION OF PESTICIDE-RESIDUES IN CONTAMINATED WATERS .1,,CLEANUP AND CONFIRMATION PROCEDURES FOR GAS-CHROMATOGRAPHIC DETERMINATION OF PESTICIDE-RESIDUES IN CONTAMINATED WATERS .1 Abs: 
1510624,Wang and  He 1993,"A STOPPED-FLOW KINETIC PROCEDURE FOR SIMULTANEOUS DETERMINATION OF IRON, ANTIMONY AND VANADIUM",,"A STOPPED-FLOW KINETIC PROCEDURE FOR SIMULTANEOUS DETERMINATION OF IRON, ANTIMONY AND VANADIUM Abs: "
1510620,Paulsen and  Andersen 1993,COMPOSITAE DERMATITIS IN A DANISH DERMATOLOGY DEPARTMENT IN 1 YEAR .2. CLINICAL-FEATURES IN PATIENTS WITH COMPOSITAE CONTACT ALLERGY,,COMPOSITAE DERMATITIS IN A DANISH DERMATOLOGY DEPARTMENT IN 1 YEAR .2. CLINICAL-FEATURES IN PATIENTS WITH COMPOSITAE CONTACT ALLERGY Abs: 
1510617,Blake et al. 1993,CHEMICAL TRANSFORMATION OF TOXIC METALS BY A PSEUDOMONAS STRAIN FROM A TOXIC-WASTE SITE,,CHEMICAL TRANSFORMATION OF TOXIC METALS BY A PSEUDOMONAS STRAIN FROM A TOXIC-WASTE SITE Abs: 
1510616,Umlas et al. 1993,SURVIVAL AND HALF-LIFE OF RED-CELLS SALVAGED AFTER HIP AND KNEE REPLACEMENT SURGERY,,SURVIVAL AND HALF-LIFE OF RED-CELLS SALVAGED AFTER HIP AND KNEE REPLACEMENT SURGERY Abs: 
1510614,Lumens et al. 1993,HYGIENIC BEHAVIOR IN CHROMIUM PLATING INDUSTRIES,,HYGIENIC BEHAVIOR IN CHROMIUM PLATING INDUSTRIES Abs: 
1510612,Matczak and  Chmielnicka 1993,RELATION BETWEEN VARIOUS CHROMIUM COMPOUNDS AND SOME OTHER ELEMENTS IN FUMES FROM MANUAL METAL ARC STAINLESS-STEEL WELDING,"For the years 1987-1990 160 individual samples of manual metal arc stainless steel (MMA/SS) welding fumes from the breathing zone of welders in four industrial plants were collected. Concentrations of soluble and insoluble chromium (Cr) III and Cr VI compounds as well as of some other welding fume elements (Fe, Mn, Ni, F) were determined. Concentration of welding fumes in the breathing zone ranged from 0.2 to 23.4 mg/m3. Total Cr amounted to 0.005-0.991 mg/m3 (including 0.005-0.842 mg/m3 Cr VI). Total Cr content of fumes varied from 0.1 to 7.4%. The distribution of particular Cr compounds was: 52.6% soluble Cr (including 50.7% Cr VI), 65.5% total Cr VI, and 11.4% insoluble Cr VI. The results obtained indicate that MMA/SS welding is a process that could be highly hazardous to human health. Evaluation of occupational exposure has shown that MMA/SS welders may exceed the admissible concentrations of soluble and insoluble Cr VI forms as well as of Mn and Ni. In the plants investigated the sum of the ratios of concentrations of particular welding fumes in the breathing zone of welders exceeded corresponding maximum allowable concentration values by 24 times (including 17 times for total Cr VI). Due to the variety and changeability of particular parameters occurring in the working environment, the composition of MMA/SS welding fumes (in the welder's breathing zone) is so variable that it is not possible to assess the exposure by means of one universal exposure indicator (maximum additive hygienic limit value). The evaluation should be based on the results of measurements of concentrations of particular elements in welding fumes.","RELATION BETWEEN VARIOUS CHROMIUM COMPOUNDS AND SOME OTHER ELEMENTS IN FUMES FROM MANUAL METAL ARC STAINLESS-STEEL WELDING Abs: For the years 1987-1990 160 individual samples of manual metal arc stainless steel (MMA/SS) welding fumes from the breathing zone of welders in four industrial plants were collected. Concentrations of soluble and insoluble chromium (Cr) III and Cr VI compounds as well as of some other welding fume elements (Fe, Mn, Ni, F) were determined. Concentration of welding fumes in the breathing zone ranged from 0.2 to 23.4 mg/m3. Total Cr amounted to 0.005-0.991 mg/m3 (including 0.005-0.842 mg/m3 Cr VI). Total Cr content of fumes varied from 0.1 to 7.4%. The distribution of particular Cr compounds was: 52.6% soluble Cr (including 50.7% Cr VI), 65.5% total Cr VI, and 11.4% insoluble Cr VI. The results obtained indicate that MMA/SS welding is a process that could be highly hazardous to human health. Evaluation of occupational exposure has shown that MMA/SS welders may exceed the admissible concentrations of soluble and insoluble Cr VI forms as well as of Mn and Ni. In the plants investigated the sum of the ratios of concentrations of particular welding fumes in the breathing zone of welders exceeded corresponding maximum allowable concentration values by 24 times (including 17 times for total Cr VI). Due to the variety and changeability of particular parameters occurring in the working environment, the composition of MMA/SS welding fumes (in the welder's breathing zone) is so variable that it is not possible to assess the exposure by means of one universal exposure indicator (maximum additive hygienic limit value). The evaluation should be based on the results of measurements of concentrations of particular elements in welding fumes."
1510610,Tubbing et al. 1993,SENSITIVITY OF PLANKTONIC PHOTOSYNTHESIS TO VARIOUS TOXICANTS IN THE RIVER RHINE,,SENSITIVITY OF PLANKTONIC PHOTOSYNTHESIS TO VARIOUS TOXICANTS IN THE RIVER RHINE Abs: 
1510609,Gulanowski et al. 1992,IMPACT OF CHROMIUM IONS ON NUCLEOSIDE TRIPHOSPHATES AND NUCLEIC-ACIDS,,IMPACT OF CHROMIUM IONS ON NUCLEOSIDE TRIPHOSPHATES AND NUCLEIC-ACIDS Abs: 
1510608,Garvey et al. 1992,ONE MINUTE OXIDATION WITH SILVER IMPREGNATION FOR FUNGI AND PNEUMOCYSTIS-CARINII,,ONE MINUTE OXIDATION WITH SILVER IMPREGNATION FOR FUNGI AND PNEUMOCYSTIS-CARINII Abs: 
1510607,Pozio et al. 1992,CRYPTOSPORIDIUM - DIFFERENT BEHAVIOR IN CALVES OF ISOLATES OF HUMAN-ORIGIN,,CRYPTOSPORIDIUM - DIFFERENT BEHAVIOR IN CALVES OF ISOLATES OF HUMAN-ORIGIN Abs: 
1510605,Boge et al. 1992,THE EFFECTS OF HEXAVALENT CHROMIUM ON THE ACTIVITY OF ALKALINE-PHOSPHATASE IN THE INTESTINE OF RAINBOW-TROUT (ONCORHYNCHUS-MYKISS),,THE EFFECTS OF HEXAVALENT CHROMIUM ON THE ACTIVITY OF ALKALINE-PHOSPHATASE IN THE INTESTINE OF RAINBOW-TROUT (ONCORHYNCHUS-MYKISS) Abs: 
1510603,Keegan et al. 1992,IMPROVED POSTTRANSFUSION QUALITY OF DENSITY SEPARATED AS-3 RED-CELLS AFTER EXTENDED STORAGE,,IMPROVED POSTTRANSFUSION QUALITY OF DENSITY SEPARATED AS-3 RED-CELLS AFTER EXTENDED STORAGE Abs: 
1510602,Kang et al. 1992,EVALUATION OF MODIFIED PASSIVE HEMAGGLUTINATION ASSAY FOR VI ANTIBODY ESTIMATION IN SALMONELLA-TYPHI INFECTIONS,,EVALUATION OF MODIFIED PASSIVE HEMAGGLUTINATION ASSAY FOR VI ANTIBODY ESTIMATION IN SALMONELLA-TYPHI INFECTIONS Abs: 
1510601,Muller and  Milin 1992,RATIONALIZATION OF STRAIN AND STERIC EFFECTS BY MOLECULAR MECHANICS CALCULATIONS,,RATIONALIZATION OF STRAIN AND STERIC EFFECTS BY MOLECULAR MECHANICS CALCULATIONS Abs: 
1510598,Jacobsen et al. 1992,INDUCTION BY CHROMIUM IONS OF CHITINASES AND POLYAMINES IN BARLEY (HORDEUM-VULGARE L) AND RAPE (BRASSICA-NAPUS L SSP OLEIFERA),,INDUCTION BY CHROMIUM IONS OF CHITINASES AND POLYAMINES IN BARLEY (HORDEUM-VULGARE L) AND RAPE (BRASSICA-NAPUS L SSP OLEIFERA) Abs: 
1510596,Patterson et al. 1992,THE EFFECTS OF 9 DIET AND WATER COMBINATIONS ON THE CULTURE HEALTH OF CERIODAPHNIA-DUBIA,,THE EFFECTS OF 9 DIET AND WATER COMBINATIONS ON THE CULTURE HEALTH OF CERIODAPHNIA-DUBIA Abs: 
1510595,Degraeve et al. 1992,VARIABILITY IN THE PERFORMANCE OF THE 7-D CERIODAPHNIA-DUBIA SURVIVAL AND REPRODUCTION TEST - AN INTRALABORATORY AND INTERLABORATORY STUDY,,VARIABILITY IN THE PERFORMANCE OF THE 7-D CERIODAPHNIA-DUBIA SURVIVAL AND REPRODUCTION TEST - AN INTRALABORATORY AND INTERLABORATORY STUDY Abs: 
1510593,Wepener et al. 1992,THE EFFECT OF HEXAVALENT CHROMIUM AT DIFFERENT PH VALUES ON THE HEMATOLOGY OF TILAPIA-SPARRMANII (CICHLIDAE),,THE EFFECT OF HEXAVALENT CHROMIUM AT DIFFERENT PH VALUES ON THE HEMATOLOGY OF TILAPIA-SPARRMANII (CICHLIDAE) Abs: 
1510592,Vanpittius et al. 1992,EFFECTS OF CHROMIUM DURING PH CHANGE ON BLOOD-COAGULATION IN TILAPIA-SPARRMANII (CICHLIDAE),,EFFECTS OF CHROMIUM DURING PH CHANGE ON BLOOD-COAGULATION IN TILAPIA-SPARRMANII (CICHLIDAE) Abs: 
1510591,Mappus et al. 1992,SYNTHESIS AND CHARACTERIZATION BY H-1 AND C-13 NUCLEAR-MAGNETIC-RESONANCE SPECTROSCOPY OF 17-ALPHA-HEXANOIC DERIVATIVES OF 5-ALPHA-DIHYDROTESTOSTERONE AND TESTOSTERONE,,SYNTHESIS AND CHARACTERIZATION BY H-1 AND C-13 NUCLEAR-MAGNETIC-RESONANCE SPECTROSCOPY OF 17-ALPHA-HEXANOIC DERIVATIVES OF 5-ALPHA-DIHYDROTESTOSTERONE AND TESTOSTERONE Abs: 
1510590,Goncalo et al. 1992,ALLERGIC CONTACT-DERMATITIS IN CHILDREN,,ALLERGIC CONTACT-DERMATITIS IN CHILDREN Abs: 
1510587,Degraeve et al. 1991,VARIABILITY IN THE PERFORMANCE OF THE 7-DAY FATHEAD MINNOW (PIMEPHALES-PROMELAS) LARVAL SURVIVAL AND GROWTH TEST - AN INTRALABORATORY AND INTERLABORATORY STUDY,,VARIABILITY IN THE PERFORMANCE OF THE 7-DAY FATHEAD MINNOW (PIMEPHALES-PROMELAS) LARVAL SURVIVAL AND GROWTH TEST - AN INTRALABORATORY AND INTERLABORATORY STUDY Abs: 
1510586,Tubbing and  Admiraal 1991,SENSITIVITY OF BACTERIOPLANKTON IN THE RHINE RIVER TO VARIOUS TOXICANTS MEASURED BY THYMIDINE INCORPORATION AND ACTIVITY OF EXOENZYMES,,SENSITIVITY OF BACTERIOPLANKTON IN THE RHINE RIVER TO VARIOUS TOXICANTS MEASURED BY THYMIDINE INCORPORATION AND ACTIVITY OF EXOENZYMES Abs: 
1510576,Rankin et al. 1991,"INTERACTIONS AMONG NEPHROTOXICANTS - N-(3,5-DICHLOROPHENYL)SUCCINIMIDE AND CEPHALORIDINE",,"INTERACTIONS AMONG NEPHROTOXICANTS - N-(3,5-DICHLOROPHENYL)SUCCINIMIDE AND CEPHALORIDINE Abs: "
1510575,Cid et al. 1991,LEATHER TANNING WORKERS - CHROMOSOMAL-ABERRATIONS IN PERIPHERAL LYMPHOCYTES AND MICRONUCLEI IN EXFOLIATED CELLS IN URINE,,LEATHER TANNING WORKERS - CHROMOSOMAL-ABERRATIONS IN PERIPHERAL LYMPHOCYTES AND MICRONUCLEI IN EXFOLIATED CELLS IN URINE Abs: 
1510574,Darweesh 2012,Reduction of Toxic Cr6+ Ions in Presence of Non Toxic Acid,,Reduction of Toxic Cr6+ Ions in Presence of Non Toxic Acid Abs: 
1510573,Kim et al. 2012,Pycnogenol (R) prevents hexavalent chromium-induced spermatotoxicity in rats,,Pycnogenol (R) prevents hexavalent chromium-induced spermatotoxicity in rats Abs: 
1510572,Rocchetta et al. 2012,Chromium induced stress conditions in heterotrophic and auxotrophic strains of Euglena gracilis,,Chromium induced stress conditions in heterotrophic and auxotrophic strains of Euglena gracilis Abs: 
1510571,Lazzarini et al. 2012,Allergic contact dermatitis among construction workers detected in a clinic that did not specialize in occupational dermatitis,,Allergic contact dermatitis among construction workers detected in a clinic that did not specialize in occupational dermatitis Abs: 
1510570,Zakaria et al. 2012,Bacterial Reduction of Cr(VI) at Technical Scale-The Malaysian Experience,,Bacterial Reduction of Cr(VI) at Technical Scale-The Malaysian Experience Abs: 
1510569,Rajkumar et al. 2012,"Isolation and Characterization of Heavy Metal Resistant Bacteria from Barak River Contaminated with Pulp Paper Mill Effluent, South Assam",,"Isolation and Characterization of Heavy Metal Resistant Bacteria from Barak River Contaminated with Pulp Paper Mill Effluent, South Assam Abs: "
1510568,Ibrahim et al. 2012,Hexavalent chromate reduction by alkaliphilic Amphibacillus sp KSUCr3 is mediated by copper-dependent membrane-associated Cr(VI) reductase,,Hexavalent chromate reduction by alkaliphilic Amphibacillus sp KSUCr3 is mediated by copper-dependent membrane-associated Cr(VI) reductase Abs: 
1510567,Jayabharathi et al. 2012,Kamlet-Taft and Catalan Studies of Some Novel Y-Shaped Imidazole Derivatives,,Kamlet-Taft and Catalan Studies of Some Novel Y-Shaped Imidazole Derivatives Abs: 
1510566,Jayabharathi et al. 2012,"Synthesis, Crystal Structure, Kamlet-Taft and Catalan Solvatochromic Analysis of Novel Imidazole Derivatives",,"Synthesis, Crystal Structure, Kamlet-Taft and Catalan Solvatochromic Analysis of Novel Imidazole Derivatives Abs: "
1510565,Wang et al. 2012,Effects of chronic chromate exposure on human serum prostate specific antigen: A cross sectional study,"The detrimental effect of chronic chromium (Cr) exposure on the prostate has never been studied. Here, we report the prostate specific antigen (PSA) changes in occupational chromate exposed workers. In this study, eighty six male occupational chromate exposed workers and forty five age-matched controls were recruited. The concentration of Cr in urine (U-Cr), serum total PSA (tPSA), free PSA (fPSA), high sensitive C reactive protein (Hs-CRP) and peripheral white blood cells count (WBC) were measured. The results show that the U-Cr, serum tPSA, Hs-CRP and WBC were significantly higher in Cr exposed workers when compared to the controls. Contrastively, the serum fPSA level in Cr exposed workers was lower than controls. A significant positive correlation between U-Cr and serum tPSA was observed. Multiple linear regression analysis revealed that serum tPSA and fPSA level was statistically associated with the serum Hs-CRP and U-Cr concentration in Cr exposed workers. These observations suggested that chronic Cr exposure could produce potential prostate injury and the nonspecific inflammation at least might be one of the reasons to explain the elevated concentration of tPSA in chronic occupational chromate exposed workers.","Effects of chronic chromate exposure on human serum prostate specific antigen: A cross sectional study Abs: The detrimental effect of chronic chromium (Cr) exposure on the prostate has never been studied. Here, we report the prostate specific antigen (PSA) changes in occupational chromate exposed workers. In this study, eighty six male occupational chromate exposed workers and forty five age-matched controls were recruited. The concentration of Cr in urine (U-Cr), serum total PSA (tPSA), free PSA (fPSA), high sensitive C reactive protein (Hs-CRP) and peripheral white blood cells count (WBC) were measured. The results show that the U-Cr, serum tPSA, Hs-CRP and WBC were significantly higher in Cr exposed workers when compared to the controls. Contrastively, the serum fPSA level in Cr exposed workers was lower than controls. A significant positive correlation between U-Cr and serum tPSA was observed. Multiple linear regression analysis revealed that serum tPSA and fPSA level was statistically associated with the serum Hs-CRP and U-Cr concentration in Cr exposed workers. These observations suggested that chronic Cr exposure could produce potential prostate injury and the nonspecific inflammation at least might be one of the reasons to explain the elevated concentration of tPSA in chronic occupational chromate exposed workers."
1510564,Volland et al. 2012,Intracellular chromium localization and cell physiological response in the unicellular alga Micrasterias,,Intracellular chromium localization and cell physiological response in the unicellular alga Micrasterias Abs: 
1510563,Caldelas et al. 2012,Ultrastructure and subcellular distribution of Cr in Iris pseudacorus L. using TEM and X-ray microanalysis,,Ultrastructure and subcellular distribution of Cr in Iris pseudacorus L. using TEM and X-ray microanalysis Abs: 
1510562,Masood et al. 2012,Prediction of Biosorption of Total Chromium by Bacillus sp. Using Artificial Neural Network,,Prediction of Biosorption of Total Chromium by Bacillus sp. Using Artificial Neural Network Abs: 
1510561,Tayybah et al. 2012,Teratological Effect of Various Sublethal Concentrations of Chromium Hexavalent [Cr(VI)] on the Gills of Cyprinus carpio,,Teratological Effect of Various Sublethal Concentrations of Chromium Hexavalent [Cr(VI)] on the Gills of Cyprinus carpio Abs: 
1510559,Agrawal and  Bajpai 2011,Biosorption of chromium(VI) ions from aqueous solutions by iron oxide-impregnated alginate nanocomposites: batch and column studies,,Biosorption of chromium(VI) ions from aqueous solutions by iron oxide-impregnated alginate nanocomposites: batch and column studies Abs: 
1510558,Zhan et al. 2012,Chromium-induced hearing loss in rats and the protective effect of copper and manganese,,Chromium-induced hearing loss in rats and the protective effect of copper and manganese Abs: 
1510557,Corazza et al. 2012,Analysis of patch test referrals: influence of appropriateness of referrals on sensitization rate,,Analysis of patch test referrals: influence of appropriateness of referrals on sensitization rate Abs: 
1510555,Flohr et al. 2012,"Effects of exposure to soluble fraction of industrial solid waste on lipid peroxidation and DNA methylation in erythrocytes of Oreochromis niloticus, as assessed by quantification of MDA and m(5)dC rates",,"Effects of exposure to soluble fraction of industrial solid waste on lipid peroxidation and DNA methylation in erythrocytes of Oreochromis niloticus, as assessed by quantification of MDA and m(5)dC rates Abs: "
1510554,Ramzan et al. 2011,Study of hematological indices in tannery workers exposed to chromium in Sheikhupura (Pakistan),,Study of hematological indices in tannery workers exposed to chromium in Sheikhupura (Pakistan) Abs: 
1510553,Andreazza et al. 2011,Bioreduction of Cu(II) by Cell-Free Copper Reductase from a Copper Resistant Pseudomonas sp NA,,Bioreduction of Cu(II) by Cell-Free Copper Reductase from a Copper Resistant Pseudomonas sp NA Abs: 
1510552,Dias da Silva et al. 2011,Evaluation of the chromium bioavailability in tanned leather shavings using the SM&T sequential extractions scheme,,Evaluation of the chromium bioavailability in tanned leather shavings using the SM&T sequential extractions scheme Abs: 
1510551,Rendina et al. 2011,"Changes in the speciation, partitioning and phytoavailability of chromium induced by organic soil amendments",,"Changes in the speciation, partitioning and phytoavailability of chromium induced by organic soil amendments Abs: "
1510550,Sen and  Dastidar 2011,BIOSORPTION OF Cr (VI) BY RESTING CELLS OF FUSARIUM SOLANI,,BIOSORPTION OF Cr (VI) BY RESTING CELLS OF FUSARIUM SOLANI Abs: 
1510549,Chiang et al. 2011,A critical exploration of blood and environmental chromium concentration among oral cancer patients in an oral cancer prevalent area of Taiwan,,A critical exploration of blood and environmental chromium concentration among oral cancer patients in an oral cancer prevalent area of Taiwan Abs: 
1510548,Klimanska et al. 2011,The importance of exposure to contact allergens in patients with allergic contact dermatitis,,The importance of exposure to contact allergens in patients with allergic contact dermatitis Abs: 
1510547,Guo et al. 2011,"Synthesis, characterization and biological evaluation of some 16E-arylidene androstane derivatives as potential anticancer agents",,"Synthesis, characterization and biological evaluation of some 16E-arylidene androstane derivatives as potential anticancer agents Abs: "
1510546,Alakoc and  Eroglu 2011,Determining mitotic index in peripheral lymphocytes of welders exposed to metal arc welding fumes,,Determining mitotic index in peripheral lymphocytes of welders exposed to metal arc welding fumes Abs: 
1510545,Jeong et al. 2011,Microarray analysis of global gene expression in Caenorhabditis elegans exposed to potassium dichromate,,Microarray analysis of global gene expression in Caenorhabditis elegans exposed to potassium dichromate Abs: 
1510544,Shaheen and  Akhtar 2011,Histological Alterations in Cyprinus carpio Kidney Due to Sublethal Concentrations of Chromium Hexavalent,,Histological Alterations in Cyprinus carpio Kidney Due to Sublethal Concentrations of Chromium Hexavalent Abs: 
1510543,Szygua et al. 2011,"The Content of Elements in Rainwater and Its Relation to the Frequency of Hospitalization for Chronic Lymphocytic Leukemia and Chronic Myeloid Leukemia in Opole Voivodship, Poland, During 2000-2002",,"The Content of Elements in Rainwater and Its Relation to the Frequency of Hospitalization for Chronic Lymphocytic Leukemia and Chronic Myeloid Leukemia in Opole Voivodship, Poland, During 2000-2002 Abs: "
1510542,Ramirez et al. 2011,"Relationships between physiological characteristics and trace metal body burdens of banded garden spiders Argiope trifasciata (Araneae, Araneidae)",,"Relationships between physiological characteristics and trace metal body burdens of banded garden spiders Argiope trifasciata (Araneae, Araneidae) Abs: "
1510541,Akbar et al. 2011,Effect of chromium and cobalt ions on primary human lymphocytes in vitro,"Cobalt-chromium (Co-Cr) alloy metal-on-metal hip resurfacing is increasingly common among younger more active patients suffering from osteoarthritis. Recent reports have increased awareness of metal ions leaching from metallic articulations; this ion exposure may have adverse effects on the immune system. As previous studies reported alterations in lymphocyte number and function in patients with Co-Cr implants, we investigated effects of clinically relevant concentrations of Cr(6+) and Co(2+) on primary human lymphocytes in vitro. Here, both resting and activated (anti-CD3 ± anti-CD28 antibodies) primary human lymphocytes were exposed to Cr(6+) or Co(2+) (0.1-100 µM). Following 24 or 48?h of exposure, cell viability, proliferation, cytokine [interferon-? (IFN? and interleukin-2 (IL-2)] release, and apoptosis (with and without pre-treatment of cells with a caspase-3 inhibitor) were assessed. Exposure to 10 and 100 µM Cr(6+) significantly decreased cell viability and increased apoptosis in both resting and activated lymphocytes. Cell proliferation and cytokine release were also significantly reduced in activated lymphocytes following exposure. The exposure of resting lymphocytes to 100 µM Co(2+) resulted in significant decreases in cell viability accompanied by a significant increase in apoptosis. Activated lymphocytes also showed this response after exposure to 100 µM Co(2+); in fact, activated cells were significantly more sensitive to Co(2+) toxicity. Exposure to 10 µM Co(2+) led to significant decreases in cell proliferation and cytokine release, but no significant increase in apoptosis, in activated cells. The results indicate that exposure to high concentrations of metal ions initiate apoptosis that results in decreased lymphocyte proliferation. IL-2 release is inhibited by both metal ions at concentrations that are not overtly toxic. However, metal ion concentrations not directly cytotoxic to lymphocytes may affect events at a molecular level, thereby impeding lymphocyte proliferation. Hence, this may contribute to altered immune system function in patients with Co-Cr implants.","Effect of chromium and cobalt ions on primary human lymphocytes in vitro Abs: Cobalt-chromium (Co-Cr) alloy metal-on-metal hip resurfacing is increasingly common among younger more active patients suffering from osteoarthritis. Recent reports have increased awareness of metal ions leaching from metallic articulations; this ion exposure may have adverse effects on the immune system. As previous studies reported alterations in lymphocyte number and function in patients with Co-Cr implants, we investigated effects of clinically relevant concentrations of Cr(6+) and Co(2+) on primary human lymphocytes in vitro. Here, both resting and activated (anti-CD3 ± anti-CD28 antibodies) primary human lymphocytes were exposed to Cr(6+) or Co(2+) (0.1-100 µM). Following 24 or 48?h of exposure, cell viability, proliferation, cytokine [interferon-? (IFN? and interleukin-2 (IL-2)] release, and apoptosis (with and without pre-treatment of cells with a caspase-3 inhibitor) were assessed. Exposure to 10 and 100 µM Cr(6+) significantly decreased cell viability and increased apoptosis in both resting and activated lymphocytes. Cell proliferation and cytokine release were also significantly reduced in activated lymphocytes following exposure. The exposure of resting lymphocytes to 100 µM Co(2+) resulted in significant decreases in cell viability accompanied by a significant increase in apoptosis. Activated lymphocytes also showed this response after exposure to 100 µM Co(2+); in fact, activated cells were significantly more sensitive to Co(2+) toxicity. Exposure to 10 µM Co(2+) led to significant decreases in cell proliferation and cytokine release, but no significant increase in apoptosis, in activated cells. The results indicate that exposure to high concentrations of metal ions initiate apoptosis that results in decreased lymphocyte proliferation. IL-2 release is inhibited by both metal ions at concentrations that are not overtly toxic. However, metal ion concentrations not directly cytotoxic to lymphocytes may affect events at a molecular level, thereby impeding lymphocyte proliferation. Hence, this may contribute to altered immune system function in patients with Co-Cr implants."
1510540,Wang et al. 2011,Renal impairment caused by chronic occupational chromate exposure,,Renal impairment caused by chronic occupational chromate exposure Abs: 
1510539,Rahmaty and  Khara 2011,"Effects of vesicular arbuscular mycorrhiza Glomus intraradices on photosynthetic pigments, antioxidant enzymes, lipid peroxidation, and chromium accumulation in maize plants treated with chromium",,"Effects of vesicular arbuscular mycorrhiza Glomus intraradices on photosynthetic pigments, antioxidant enzymes, lipid peroxidation, and chromium accumulation in maize plants treated with chromium Abs: "
1510538,Mangaiyarkarasi et al. 2011,Bioreduction of Cr(VI) by alkaliphilic Bacillus subtilis and interaction of the membrane groups,,Bioreduction of Cr(VI) by alkaliphilic Bacillus subtilis and interaction of the membrane groups Abs: 
1510537,Petruzzelli et al. 2011,Chemical and geochemical characterisation of a disused red brick factory area of central Italy,,Chemical and geochemical characterisation of a disused red brick factory area of central Italy Abs: 
1510535,Saravanan et al. 2011,Synthesis and Photophysics of Some Novel Imidazole Derivatives Used as Sensitive Fluorescent Chemisensors,,Synthesis and Photophysics of Some Novel Imidazole Derivatives Used as Sensitive Fluorescent Chemisensors Abs: 
1510534,Upadhyay and  Panda 2010,Influence of Chromium Salts on Increased Lipid Peroxidation and Differential Pattern in Antioxidant Metabolism in Pistia stratiotes L,,Influence of Chromium Salts on Increased Lipid Peroxidation and Differential Pattern in Antioxidant Metabolism in Pistia stratiotes L Abs: 
1510533,Wani and  Khan 2010,Bacillus species enhance growth parameters of chickpea (Cicer arietinum L.) in chromium stressed soils,,Bacillus species enhance growth parameters of chickpea (Cicer arietinum L.) in chromium stressed soils Abs: 
1510532,Diwan et al. 2010,Uptake-related parameters as indices of phytoremediation potential,,Uptake-related parameters as indices of phytoremediation potential Abs: 
1510531,Dvorak et al. 2010,Use of the Crustacean Artemia franciscana for Alternative Biotests,,Use of the Crustacean Artemia franciscana for Alternative Biotests Abs: 
1510530,Sharma and  Mishra 2010,Microwave induced beta-cyclodextrin modification of chitosan for lead sorption,,Microwave induced beta-cyclodextrin modification of chitosan for lead sorption Abs: 
1510529,Rodgher et al. 2010,Suitability of Daphnia similis as an alternative organism in ecotoxicological tests: implications for metal toxicity,,Suitability of Daphnia similis as an alternative organism in ecotoxicological tests: implications for metal toxicity Abs: 
1510528,Gandhi et al. 2010,Preparation and application of alumina/chitosan biocomposite,,Preparation and application of alumina/chitosan biocomposite Abs: 
1510527,Mallick et al. 2010,"Interactive effects of Cr and Fe treatments on plants growth, nutrition and oxidative status in Zea mays L",,"Interactive effects of Cr and Fe treatments on plants growth, nutrition and oxidative status in Zea mays L Abs: "
1510526,Cheng et al. 2010,The Selenium-independent Inherent Pro-oxidant NADPH Oxidase Activity of Mammalian Thioredoxin Reductase and Its Selenium-dependent Direct Peroxidase Activities,,The Selenium-independent Inherent Pro-oxidant NADPH Oxidase Activity of Mammalian Thioredoxin Reductase and Its Selenium-dependent Direct Peroxidase Activities Abs: 
1510525,Unal et al. 2010,Effects of Chromium VI stress on green alga Ulva lactuca (L.),,Effects of Chromium VI stress on green alga Ulva lactuca (L.) Abs: 
1510524,Rackham et al. 2010,Predictors of Serum Chromium Levels After Stainless Steel Posterior Spinal Instrumentation for Adolescent Idiopathic Scoliosis,,Predictors of Serum Chromium Levels After Stainless Steel Posterior Spinal Instrumentation for Adolescent Idiopathic Scoliosis Abs: 
1510523,Cundy et al. 2010,Chromium Ion Release From Stainless Steel Pediatric Scoliosis Instrumentation,,Chromium Ion Release From Stainless Steel Pediatric Scoliosis Instrumentation Abs: 
1510521,Levine et al. 2010,Validation and Application of a Method for the Determination of Total Chromium in Rat Tissues by Inductively Coupled Plasma Mass Spectrometry,,Validation and Application of a Method for the Determination of Total Chromium in Rat Tissues by Inductively Coupled Plasma Mass Spectrometry Abs: 
1510520,Chatterjee and  Luo 2010,Cr-(III)-organic compounds treatment causes genotoxicity and changes in DNA and protein level in Saccharomyces cerevisiae,,Cr-(III)-organic compounds treatment causes genotoxicity and changes in DNA and protein level in Saccharomyces cerevisiae Abs: 
1510519,Gurame et al. 2010,Kinetic and mechanistic study of oxidation of l-methionine by Waugh-type enneamolybdomanganate(IV) in perchloric acid,,Kinetic and mechanistic study of oxidation of l-methionine by Waugh-type enneamolybdomanganate(IV) in perchloric acid Abs: 
1510518,Stromajer-Racz et al. 2010,Oxidative stress induced by HIV-1 F34IVpr in Schizosaccharomyces pombe is one of its multiple functions,,Oxidative stress induced by HIV-1 F34IVpr in Schizosaccharomyces pombe is one of its multiple functions Abs: 
1510517,Zitova et al. 2009,Respirometric acute toxicity screening assay using Daphnia magna,,Respirometric acute toxicity screening assay using Daphnia magna Abs: 
1510516,Chatterjee et al. 2009,Uptake and distribution of chromium in Saccharomyces cerevisae exposed to Cr(III)-organic compounds,,Uptake and distribution of chromium in Saccharomyces cerevisae exposed to Cr(III)-organic compounds Abs: 
1510515,Thyssen et al. 2009,The prevalence of chromium allergy in Denmark is currently increasing as a result of leather exposure,,The prevalence of chromium allergy in Denmark is currently increasing as a result of leather exposure Abs: 
1510514,Moukarzel 2009,Chromium in Parenteral Nutrition: Too Little or Too Much?,,Chromium in Parenteral Nutrition: Too Little or Too Much? Abs: 
1510513,Mihalikova et al. 2009,"Tolerance of a ruminant ciliate Entodinium caudatum against mercury, copper and chromium",,"Tolerance of a ruminant ciliate Entodinium caudatum against mercury, copper and chromium Abs: "
1510512,Harrison et al. 2009,Chromosomal antioxidant genes have metal ion-specific roles as determinants of bacterial metal tolerance,,Chromosomal antioxidant genes have metal ion-specific roles as determinants of bacterial metal tolerance Abs: 
1510511,Jabari et al. 2009,The treatment of chromium tanning wastewater using natural marl,,The treatment of chromium tanning wastewater using natural marl Abs: 
1510510,Soares et al. 2009,Simultaneous speciation of chromium by spectrophotometry and multicomponent analysis,,Simultaneous speciation of chromium by spectrophotometry and multicomponent analysis Abs: 
1510509,Ranjan et al. 2009,Biosorption of Cr(VI) from Water Using Biomass of Aeromonas hydrophila: Central Composite Design for Optimization of Process Variables,,Biosorption of Cr(VI) from Water Using Biomass of Aeromonas hydrophila: Central Composite Design for Optimization of Process Variables Abs: 
1510508,Lee et al. 2009,"Multi-level ecotoxicity assay on the aquatic midge, Chironomus tentans (Diptera, Chironomidae) exposed to octachlorostyrene",,"Multi-level ecotoxicity assay on the aquatic midge, Chironomus tentans (Diptera, Chironomidae) exposed to octachlorostyrene Abs: "
1510507,Li et al. 2009,"Influence of marine phytoplankton, transition metals and sunlight on the species distribution of chromium in surface seawater",,"Influence of marine phytoplankton, transition metals and sunlight on the species distribution of chromium in surface seawater Abs: "
1510489,Illner et al. 2009,Nearly a stairway to heaven - severe dichromate intoxication in a young man,,Nearly a stairway to heaven - severe dichromate intoxication in a young man Abs: 
1510488,Zabulyte et al. 2009,Investigation of combined effect of chromium (VI) and sodium fluoride in experiments on rats,"Chromium [Cr (VI)] is an environmental pollutant and industrial contaminant. Non-occupational sources of exposure to chromium include food, air and water, but the levels are usually lower than those typically encountered in occupational situations. The widespread distribution of sodium fluoride (NaF) in the environment through drinking water and food often results in adverse health effects. Human beings are constantly exposed to mixture of these substances. Aim of the study: To investigate the combined effect of Cr (VI) and NaF on the organism of Wistar rats at the oral route of administration. Material and methods: Tests on general toxicity were conducted on the basis of methodical recommendation 408 of the Organization For Economic Co-operation and Development Guideline For Testing of Chemicals: ""Subchronic Oral Toxicity - Rodent: 90-day Study"" [OECD Guideline 1993]. The experiments have been carried out on 32 male Wistar rats. The effects of tested substances were characterized by antagonistic, synergistic, additive and unknown type of combined action of them. Results: According to the blood biochemical indices the following combined effect of tested chemicals was determined: antagonistic, additive and unknown. According to the tested parameters of the rats reproductive system the combined action type of substances was mostly antagonistic. The same effect was observed during the analysis of hematological parameters.","Investigation of combined effect of chromium (VI) and sodium fluoride in experiments on rats Abs: Chromium [Cr (VI)] is an environmental pollutant and industrial contaminant. Non-occupational sources of exposure to chromium include food, air and water, but the levels are usually lower than those typically encountered in occupational situations. The widespread distribution of sodium fluoride (NaF) in the environment through drinking water and food often results in adverse health effects. Human beings are constantly exposed to mixture of these substances. Aim of the study: To investigate the combined effect of Cr (VI) and NaF on the organism of Wistar rats at the oral route of administration. Material and methods: Tests on general toxicity were conducted on the basis of methodical recommendation 408 of the Organization For Economic Co-operation and Development Guideline For Testing of Chemicals: ""Subchronic Oral Toxicity - Rodent: 90-day Study"" [OECD Guideline 1993]. The experiments have been carried out on 32 male Wistar rats. The effects of tested substances were characterized by antagonistic, synergistic, additive and unknown type of combined action of them. Results: According to the blood biochemical indices the following combined effect of tested chemicals was determined: antagonistic, additive and unknown. According to the tested parameters of the rats reproductive system the combined action type of substances was mostly antagonistic. The same effect was observed during the analysis of hematological parameters."
1510486,Minakata et al. 2008,Determination of Urine Luck in urine using electrospray ionization tandem mass spectrometry,,Determination of Urine Luck in urine using electrospray ionization tandem mass spectrometry Abs: 
1510485,Shiyab et al. 2009,Phytotoxicity of mercury in Indian mustard (Brassica juncea L.),,Phytotoxicity of mercury in Indian mustard (Brassica juncea L.) Abs: 
1510484,Juneja et al. 2008,Electrophoretic study of chromium speciation in xylem sap of maize (Winter Crop),,Electrophoretic study of chromium speciation in xylem sap of maize (Winter Crop) Abs: 
1510483,Asgari et al. 2008,REMOVAL OF HEXAVALENT CHROMIUM FROM DRINKING WATER BY GRANULAR FERRIC HYDROXIDE,,REMOVAL OF HEXAVALENT CHROMIUM FROM DRINKING WATER BY GRANULAR FERRIC HYDROXIDE Abs: 
1510482,Mishra and  Doble 2008,"Novel chromium tolerant microorganisms: Isolation, characterization and their biosorption capacity",,"Novel chromium tolerant microorganisms: Isolation, characterization and their biosorption capacity Abs: "
1510481,Wang et al. 2008,Degradation of dimethyl carboxylic phthalate ester by Burkholderia cepacia DA2 isolated from marine sediment of South China Sea,"Burkholderia cepacia DA2, isolated from marine sediment of the South China Sea, is capable of utilizing dimethyl phthalate (DMP) as the sole source of carbon and energy. During the transformation of DMP in batch culture, its corresponding degradation intermediates were identified as monomethyl phthalate (MMP) and phthalate acid (PA) sequentially over the time of incubation. The biodegradation biochemical pathway of DMP was DMP to MMP and then to PA before mineralization. Degradation of DMP by B. cepacia DA2 was also dependent upon DMP-induction, and the initial concentrations of DMP affected the degradation rate. Degradation kinetics fit well with the modified Gompertz model. The optimum pH and salinity was 6.0 and &lt; 5 per thousand, respectively, for DMP degradation by B. cepacia DA2. This study showed that the indigenous microorganisms of the deep-ocean sediments are capable of DMP degradation completely.","Degradation of dimethyl carboxylic phthalate ester by Burkholderia cepacia DA2 isolated from marine sediment of South China Sea Abs: Burkholderia cepacia DA2, isolated from marine sediment of the South China Sea, is capable of utilizing dimethyl phthalate (DMP) as the sole source of carbon and energy. During the transformation of DMP in batch culture, its corresponding degradation intermediates were identified as monomethyl phthalate (MMP) and phthalate acid (PA) sequentially over the time of incubation. The biodegradation biochemical pathway of DMP was DMP to MMP and then to PA before mineralization. Degradation of DMP by B. cepacia DA2 was also dependent upon DMP-induction, and the initial concentrations of DMP affected the degradation rate. Degradation kinetics fit well with the modified Gompertz model. The optimum pH and salinity was 6.0 and &lt; 5 per thousand, respectively, for DMP degradation by B. cepacia DA2. This study showed that the indigenous microorganisms of the deep-ocean sediments are capable of DMP degradation completely."
1510480,Hill et al. 2008,Chromium-mediated apoptosis: Involvement of DNA-dependent protein kinase (DNA-PK) and differential induction of p53 target genes,,Chromium-mediated apoptosis: Involvement of DNA-dependent protein kinase (DNA-PK) and differential induction of p53 target genes Abs: 
1510479,Mahmoud et al. 2008,Development of a method for chromium speciation by selective solid phase extraction and preconcentration on alumina-functionalized thiosemicarbazide,,Development of a method for chromium speciation by selective solid phase extraction and preconcentration on alumina-functionalized thiosemicarbazide Abs: 
1510478,Qu et al. 2008,Cr(VI) exposure and biomarkers: Cr in erythrocytes in relation to exposure and polymorphisms of genes encoding anion transport proteins,,Cr(VI) exposure and biomarkers: Cr in erythrocytes in relation to exposure and polymorphisms of genes encoding anion transport proteins Abs: 
1510477,Rodgher and  Espindola 2008,"The influence of algal densities on the toxicity of chromium for Ceriodaphnia dubia Richard (Cladocera, Crustacea)",,"The influence of algal densities on the toxicity of chromium for Ceriodaphnia dubia Richard (Cladocera, Crustacea) Abs: "
1510476,Kiran et al. 2008,Metal-salt co-tolerance and metal removal by indigenous cyanobacterial strains,,Metal-salt co-tolerance and metal removal by indigenous cyanobacterial strains Abs: 
1510475,Torelli et al. 2008,Identification of S-2-TA63: A cDNA fragment corresponding to a gene differentially expressed in a Cr-tolerant strain of the unicellular green alga Scenedesmus acutus,,Identification of S-2-TA63: A cDNA fragment corresponding to a gene differentially expressed in a Cr-tolerant strain of the unicellular green alga Scenedesmus acutus Abs: 
1510474,Fucic et al. 2008,Spontaneous abortions in female populations occupationally exposed to ionizing radiation,,Spontaneous abortions in female populations occupationally exposed to ionizing radiation Abs: 
1510473,Ha et al. 2008,Chemical-induced alteration of hemoglobin expression in the 4th instar larvae of Chironomus tentans Mg. (Diptera : Chironomidae),,Chemical-induced alteration of hemoglobin expression in the 4th instar larvae of Chironomus tentans Mg. (Diptera : Chironomidae) Abs: 
1510472,Sharma et al. 2007,Biosorption of trivalent and hexavalent chromium from aqueous systems using shelled Moringa oleifera seeds,,Biosorption of trivalent and hexavalent chromium from aqueous systems using shelled Moringa oleifera seeds Abs: 
1510471,Levina et al. 2007,Reactivity of potential anti-diabetic molybdenum(VI) complexes in biological media: A XANES spectroscopic study,,Reactivity of potential anti-diabetic molybdenum(VI) complexes in biological media: A XANES spectroscopic study Abs: 
1510470,Sridevi and  Yusuff 2007,Rapid in vitro screening of drug-metal ion interactions,,Rapid in vitro screening of drug-metal ion interactions Abs: 
1510469,Castillo et al. 2007,"Secondary interactions, an unexpected problem emerged between hydroxyl containing analytes and fused silica capillaries in anion-exchange micro-liquid chromatography",,"Secondary interactions, an unexpected problem emerged between hydroxyl containing analytes and fused silica capillaries in anion-exchange micro-liquid chromatography Abs: "
1510468,Basha and  Murthy 2007,"Kinetic and equilibrium models for biosorption of Cr(VI) on chemically modified seaweed, Cystoseira indica",,"Kinetic and equilibrium models for biosorption of Cr(VI) on chemically modified seaweed, Cystoseira indica Abs: "
1510467,Sorensen et al. 2007,Risk of lung cancer according to mild steel and stainless steel welding,,Risk of lung cancer according to mild steel and stainless steel welding Abs: 
1510466,Amoozegar et al. 2007,"Evaluation of hexavalent chromium reduction by chromate-resistant moderately halophile, Nesterenkonia sp strain MF2",,"Evaluation of hexavalent chromium reduction by chromate-resistant moderately halophile, Nesterenkonia sp strain MF2 Abs: "
1510465,Rai et al. 2007,Disruption of elements uptake due to excess chromium in indian medicinal plants,,Disruption of elements uptake due to excess chromium in indian medicinal plants Abs: 
1510464,Hasani et al. 2007,"Spectrophotometric resolution of ternary mixtures of tryptophan, tyrosine, and histidine with the aid of principal component-artificial neural network models",,"Spectrophotometric resolution of ternary mixtures of tryptophan, tyrosine, and histidine with the aid of principal component-artificial neural network models Abs: "
1510463,Ergene et al. 2007,Evaluation of river water genotoxicity using the piscine micronucleus test,,Evaluation of river water genotoxicity using the piscine micronucleus test Abs: 
1510462,Berden-Zrimec et al. 2007,Delayed fluorescence in algal growth inhibition tests,,Delayed fluorescence in algal growth inhibition tests Abs: 
1510461,Ksheminska et al. 2006,Extra-cellular chromate-reducing activity of the yeast cultures,,Extra-cellular chromate-reducing activity of the yeast cultures Abs: 
1510460,Li et al. 2007,Short-column CE coupled with inductively coupled plasma MS for high-throughput speciation analysis of chromium,,Short-column CE coupled with inductively coupled plasma MS for high-throughput speciation analysis of chromium Abs: 
1510459,El Nemr et al. 2007,Removal of toxic chromium (VI) from aqueous solution by activated carbon using Casuarina equisetifolio,,Removal of toxic chromium (VI) from aqueous solution by activated carbon using Casuarina equisetifolio Abs: 
1510458,Baral et al. 2007,"Removal of Cr(VI) from aqueous solution using waste weed, Salvinia cucullata",,"Removal of Cr(VI) from aqueous solution using waste weed, Salvinia cucullata Abs: "
1510456,Benova et al. 2007,"Interaction of low doses of ionizing radiation, potassium dichromate and cadmium chloride in Artemia franciscana biotest",,"Interaction of low doses of ionizing radiation, potassium dichromate and cadmium chloride in Artemia franciscana biotest Abs: "
1510455,Castro et al. 2007,Effects of dichromate on growth and root system architecture of Arabidopsis thaliana seedlings,,Effects of dichromate on growth and root system architecture of Arabidopsis thaliana seedlings Abs: 
1510454,Forcella et al. 2007,Increased alanine concentration is associated with exposure to fenitrothion but not carbamates in Chironomus riparius larvae,,Increased alanine concentration is associated with exposure to fenitrothion but not carbamates in Chironomus riparius larvae Abs: 
1510453,Abdelwahab et al. 2007,Mass-transfer processes of chromium(VI) adsorption onto guava seeds,,Mass-transfer processes of chromium(VI) adsorption onto guava seeds Abs: 
1510452,Tang et al. 2007,Shewanella oneidensis MR-1 fluxome under various oxygen conditions,,Shewanella oneidensis MR-1 fluxome under various oxygen conditions Abs: 
1510451,Onyenwoke et al. 2007,Iron(III) reduction: A novel activity of the human NAD(P)H : oxidoreductase,,Iron(III) reduction: A novel activity of the human NAD(P)H : oxidoreductase Abs: 
1510449,Lee et al. 2006,"Multilevel evaluation of nonylphenol toxicity in fourth-instar larvae of Chironomus riparius (Diptera, Chironomidae)",,"Multilevel evaluation of nonylphenol toxicity in fourth-instar larvae of Chironomus riparius (Diptera, Chironomidae) Abs: "
1510448,Zabulyte et al. 2006,Investigation of combined effect of chromium (VI) and nitrate in experiments on rats,"Chromium (VI) is an ubiquitous environmental and industrial contaminant. Nitrate is one of the most frequent groundwater pollutants in rural areas. It is known that these compounds can cause adverse effects on health. The aim of the study was to investigate the combined effect of chromium (VI) (Cr (VI)) and nitrate (NO3-) on the organism of Wistar rats at the oral route of administration. Material and methods: Tests on general toxicity were conducted on the basis of methodical recommendations 407 and 408 of the organization for economic co-operation and development guideline for testing of chemicals: repeated-dose oral toxicity rodent: 28-day or 14-day study and subchronic oral toxicity rodent: 90-day study [OECD Guideline 1993]. The experiments have been carried out on 64 male Wistar rats. The effects of tested substances were characterized by four types of combined action of them: antagonistic, additive, synergistic and unknown. Results: According to the blood biochemical indices the following combined effect of tested chemicals was determined: antagonistic 50%, synergistic 33.3%, additive 16.6%. Analysis of the complex of substances under the study by the parameters of orientation reactions showed that the combined effect of substances was mostly antagonistic. According to the tested parameters of the male rats reproductive system these types of combined action of substances were identified as follows: antagonistic (20%), additive (40%) and unknown (40%). Methemoglobinemia was noted in groups given nitrate and Cr(VI) + NO3- complex.","Investigation of combined effect of chromium (VI) and nitrate in experiments on rats Abs: Chromium (VI) is an ubiquitous environmental and industrial contaminant. Nitrate is one of the most frequent groundwater pollutants in rural areas. It is known that these compounds can cause adverse effects on health. The aim of the study was to investigate the combined effect of chromium (VI) (Cr (VI)) and nitrate (NO3-) on the organism of Wistar rats at the oral route of administration. Material and methods: Tests on general toxicity were conducted on the basis of methodical recommendations 407 and 408 of the organization for economic co-operation and development guideline for testing of chemicals: repeated-dose oral toxicity rodent: 28-day or 14-day study and subchronic oral toxicity rodent: 90-day study [OECD Guideline 1993]. The experiments have been carried out on 64 male Wistar rats. The effects of tested substances were characterized by four types of combined action of them: antagonistic, additive, synergistic and unknown. Results: According to the blood biochemical indices the following combined effect of tested chemicals was determined: antagonistic 50%, synergistic 33.3%, additive 16.6%. Analysis of the complex of substances under the study by the parameters of orientation reactions showed that the combined effect of substances was mostly antagonistic. According to the tested parameters of the male rats reproductive system these types of combined action of substances were identified as follows: antagonistic (20%), additive (40%) and unknown (40%). Methemoglobinemia was noted in groups given nitrate and Cr(VI) + NO3- complex."
1510447,Ahmad et al. 2006,Oxidative stress and genotoxic effects in gill and kidney of Anguilla anguilla L. exposed to chromium with or without pre-exposure to beta-naphthoflavone,,Oxidative stress and genotoxic effects in gill and kidney of Anguilla anguilla L. exposed to chromium with or without pre-exposure to beta-naphthoflavone Abs: 
1510446,Liu et al. 2006,Cr(VI) reduction by Bacillus sp isolated from chromium landfill,,Cr(VI) reduction by Bacillus sp isolated from chromium landfill Abs: 
1510445,Gorbi et al. 2006,Differential responses to Cr(VI)-induced oxidative stress between Cr-tolerant and wild-type strains of Scenedesmus acutus (Chlorophyceae),,Differential responses to Cr(VI)-induced oxidative stress between Cr-tolerant and wild-type strains of Scenedesmus acutus (Chlorophyceae) Abs: 
1510444,Krejci and  Palikova 2006,Potassium dichromate as a reference substance for embryonic tests of toxicity in the common carp (Cyprinus carpio L.),,Potassium dichromate as a reference substance for embryonic tests of toxicity in the common carp (Cyprinus carpio L.) Abs: 
1510443,Daulton and  Little 2006,Determination of chromium valence over the range Cr(0)-Cr(VI) by electron energy loss spectroscopy,,Determination of chromium valence over the range Cr(0)-Cr(VI) by electron energy loss spectroscopy Abs: 
1510442,Chandra et al. 2006,In vivo genotoxic effects of industrial waste leachates in mice following oral exposure,,In vivo genotoxic effects of industrial waste leachates in mice following oral exposure Abs: 
1510441,Rao et al. 2006,Vitamin-E supplementation ameliorates chromium-and/or nickel induced oxidative stress in vivo,"The present study was designed to investigate the in vivo effects of nickel chloride [NiCl2,; 8, and 16 mg/kg body weight (b wt)] and/or Potassium dichromate (K2Cr2O7; 5 and 10 mg/kg b wt) in the liver of adult mice. The beneficial effects of vitamin E (2 mg/kg) along with their combination were also studied. The antioxidative indices including oxidative lipid peroxidation (LPO) and antioxidative enzymes such as glutathione (GSH), total sulfhydryl (-SH) groups, total ascorbic acid (TAA), superoxide dismutase (SOD) and catalase (CAT) were evaluated in the hepatic tissue using well established techniques. Nickel and/or chromium treatments to mice revealed a significant decline in the levels of these antioxidant parameters as compared to control. Concomitantly a significant increase in lipid peroxidation was obtained. These data indicated that the treatment induced oxidative stress in the hepatic tissue of treated mice, which was more pronounced by combination of metal salts. But Supplementation of vitamin E with NiCl2 + K2Cr2O7 to mice exerted no significant alterations in the liver antioxidant system as compared to control, thus indicating its ameliorative role. These findings suggest that vitamin E prevents LPO and protects the antioxidant system in the mouse liver.","Vitamin-E supplementation ameliorates chromium-and/or nickel induced oxidative stress in vivo Abs: The present study was designed to investigate the in vivo effects of nickel chloride [NiCl2,; 8, and 16 mg/kg body weight (b wt)] and/or Potassium dichromate (K2Cr2O7; 5 and 10 mg/kg b wt) in the liver of adult mice. The beneficial effects of vitamin E (2 mg/kg) along with their combination were also studied. The antioxidative indices including oxidative lipid peroxidation (LPO) and antioxidative enzymes such as glutathione (GSH), total sulfhydryl (-SH) groups, total ascorbic acid (TAA), superoxide dismutase (SOD) and catalase (CAT) were evaluated in the hepatic tissue using well established techniques. Nickel and/or chromium treatments to mice revealed a significant decline in the levels of these antioxidant parameters as compared to control. Concomitantly a significant increase in lipid peroxidation was obtained. These data indicated that the treatment induced oxidative stress in the hepatic tissue of treated mice, which was more pronounced by combination of metal salts. But Supplementation of vitamin E with NiCl2 + K2Cr2O7 to mice exerted no significant alterations in the liver antioxidant system as compared to control, thus indicating its ameliorative role. These findings suggest that vitamin E prevents LPO and protects the antioxidant system in the mouse liver."
1510439,Prieco-Capote and  de Castro 2006,Speciation of chromium by in-capillary derivatization and electrophoretically mediated microanalysis,,Speciation of chromium by in-capillary derivatization and electrophoretically mediated microanalysis Abs: 
1510438,Farag et al. 2006,The effect of chronic chromium exposure on the health of Chinook salmon (Oncorhynchus tshawytscha),,The effect of chronic chromium exposure on the health of Chinook salmon (Oncorhynchus tshawytscha) Abs: 
1510437,Aubriet et al. 2006,"Activation processes and polyethylene formation on a Phillips model catalyst studied by laser ablation, laser desorption, and static secondary ion mass spectrometry",,"Activation processes and polyethylene formation on a Phillips model catalyst studied by laser ablation, laser desorption, and static secondary ion mass spectrometry Abs: "
1510436,Juneja and  Prakash 2005,The chemical form of trivalent chromium in xylem sap of maize (Zea mays L.),,The chemical form of trivalent chromium in xylem sap of maize (Zea mays L.) Abs: 
1510434,Chen et al. 2005,Biosorption of copper(II) and zinc(II) from aqueous solution by Pseudomonas putida CZ1,,Biosorption of copper(II) and zinc(II) from aqueous solution by Pseudomonas putida CZ1 Abs: 
1510432,Oliveira et al. 2005,Equilibrium studies for the sorption of chromium and nickel from aqueous solutions using raw rice bran,,Equilibrium studies for the sorption of chromium and nickel from aqueous solutions using raw rice bran Abs: 
1510430,Park et al. 2005,Use of dead fungal biomass for the detoxification of hexavalent chromium: screening and kinetics,,Use of dead fungal biomass for the detoxification of hexavalent chromium: screening and kinetics Abs: 
1510429,Arica et al. 2005,"Utilisation of native, heat and acid-treated microalgae Chlamydomonas reinhardtii preparations for biosorption of Cr(VI) ions",,"Utilisation of native, heat and acid-treated microalgae Chlamydomonas reinhardtii preparations for biosorption of Cr(VI) ions Abs: "
1510428,Foronda et al. 2005,"Parasites (viruses, coccidia and helminths) of the wild rabbit (Oryctolagus cuniculus) introduced to Canary Islands from Iberian Peninsula",,"Parasites (viruses, coccidia and helminths) of the wild rabbit (Oryctolagus cuniculus) introduced to Canary Islands from Iberian Peninsula Abs: "
1510426,Ksheminska et al. 2005,Chromium(III) and (VI) tolerance and bioaccumulation in yeast: A survey of cellular chromium content in selected strains of representative genera,,Chromium(III) and (VI) tolerance and bioaccumulation in yeast: A survey of cellular chromium content in selected strains of representative genera Abs: 
1510425,Kaszycki et al. 2005,Exogenously applied sulphate as a tool to investigate transport and reduction of chromate in the duckweed Spirodela polyrhiza,,Exogenously applied sulphate as a tool to investigate transport and reduction of chromate in the duckweed Spirodela polyrhiza Abs: 
1510424,Ferroni et al. 2004,Adaptive modifications of the photosynthetic apparatus in Euglena gracilis Klebs exposed to manganese excess,,Adaptive modifications of the photosynthetic apparatus in Euglena gracilis Klebs exposed to manganese excess Abs: 
1510423,Carmona et al. 2005,Biosorption of chromium using factorial experimental design,,Biosorption of chromium using factorial experimental design Abs: 
1510422,De Mattia et al. 2004,Impairment of cell and plasma redox state in subjects professionally exposed to chromium,,Impairment of cell and plasma redox state in subjects professionally exposed to chromium Abs: 
1510421,Armas et al. 2004,Speciation in the chromium(III)-glutathione system,,Speciation in the chromium(III)-glutathione system Abs: 
1510419,Fiol et al. 2004,Chromium(VI) uptake by grape stalks wastes encapsulated in calcium alginate beads: equilibrium and kinetics studies,,Chromium(VI) uptake by grape stalks wastes encapsulated in calcium alginate beads: equilibrium and kinetics studies Abs: 
1510418,di Toppi et al. 2004,Responses of Xanthoria parietina thalli to environmentally relevant concentrations of hexavalent chromium,,Responses of Xanthoria parietina thalli to environmentally relevant concentrations of hexavalent chromium Abs: 
1510417,Zouboulis et al. 2004,Biosorption of toxic metals from aqueous solutions by bacteria strains isolated from metal-polluted soils,,Biosorption of toxic metals from aqueous solutions by bacteria strains isolated from metal-polluted soils Abs: 
1510416,Shanker et al. 2004,Differential antioxidative response of ascorbate glutathione pathway enzymes and metabolites to chromium speciation stress in green gram (Vigna radiata (L.) R.Wilczek. cv CO 4) roots,,Differential antioxidative response of ascorbate glutathione pathway enzymes and metabolites to chromium speciation stress in green gram (Vigna radiata (L.) R.Wilczek. cv CO 4) roots Abs: 
1510415,Liu and  Sunderland 2004,Determination of sulfate in aminoglycoside antibiotics by capillary electrophoresis with indirect UV detection,,Determination of sulfate in aminoglycoside antibiotics by capillary electrophoresis with indirect UV detection Abs: 
1510414,Maples and  Bain 2004,Trivalent chromium alters gene expression in the mummichog (Fundulus heteroclitus),,Trivalent chromium alters gene expression in the mummichog (Fundulus heteroclitus) Abs: 
1510412,Liu et al. 2002,Removal of Cr6+ from groundwater using zero-valence iron in the laboratory,,Removal of Cr6+ from groundwater using zero-valence iron in the laboratory Abs: 
1510411,Chang et al. 2003,The putative transcriptional activator MSN1 promotes chromium accumulation in Saccharomyces cerevisiae,,The putative transcriptional activator MSN1 promotes chromium accumulation in Saccharomyces cerevisiae Abs: 
1510410,Kabir-ud-din et al. 2003,Micellar effects on the oxidation of D-glucose by chromic acid in perchloric acidic medium,,Micellar effects on the oxidation of D-glucose by chromic acid in perchloric acidic medium Abs: 
1510409,Shkumatov et al. 2003,"Oxidation of 17 alpha,20 beta- and 17 alpha,20 alpha-dihydroxypregn-4-en-3-ones, side products of progesterone biotransformation with recombinant microorganisms expressing cytochrome P-45017 alpha",,"Oxidation of 17 alpha,20 beta- and 17 alpha,20 alpha-dihydroxypregn-4-en-3-ones, side products of progesterone biotransformation with recombinant microorganisms expressing cytochrome P-45017 alpha Abs: "
1510408,Danadevi et al. 2004,Genotoxic evaluation of welders occupationally exposed to chromium and nickel using the Comet and micronucleus assays,"Chromium (Cr) and nickel (Ni) are widely used industrial chemicals. Welders in India are inclined to possible occupational Cr and Ni exposure. The carcinogenic potential of metals is a major issue in defining human health risk from exposure. Hence, in the present investigation, 102 welders and an equal number of control subjects were monitored for DNA damage in blood leucocytes utilizing the Comet assay. The two groups had similar mean ages and smoking prevalences. A few subjects were randomly selected for estimation of Cr and Ni content in whole blood by inductively coupled plasma mass spectrometry. The Comet assay was carried out to quantify basal DNA damage. The mean comet tail length was used to measure DNA damage. Welders had higher Cr and Ni content when compared with controls (Cr, 151.65 versus 17.86 micro g/l; Ni 132.39 versus 16.91 micro g/l; P &lt; 0.001). The results indicated that the welders had a larger mean comet tail length than that of the controls (mean +/- SD, 23.05 +/- 3.86 versus 8.94 +/- 3.16; P &lt; 0.001). In addition, the micronucleus test on buccal epithelial cells was carried out in a few randomly selected subjects. Welders showed a significant increase in micronucleated cells compared with controls (1.30 versus 0.32; P &lt; 0.001). Analysis of variance revealed that occupational exposure (P &lt; 0.05) had a significant effect on DNA mean tail length, whereas smoking and age had no significant effect on DNA damage. The current study suggested that chronic occupational exposure to Cr and Ni during welding could lead to increased levels of DNA damage.","Genotoxic evaluation of welders occupationally exposed to chromium and nickel using the Comet and micronucleus assays Abs: Chromium (Cr) and nickel (Ni) are widely used industrial chemicals. Welders in India are inclined to possible occupational Cr and Ni exposure. The carcinogenic potential of metals is a major issue in defining human health risk from exposure. Hence, in the present investigation, 102 welders and an equal number of control subjects were monitored for DNA damage in blood leucocytes utilizing the Comet assay. The two groups had similar mean ages and smoking prevalences. A few subjects were randomly selected for estimation of Cr and Ni content in whole blood by inductively coupled plasma mass spectrometry. The Comet assay was carried out to quantify basal DNA damage. The mean comet tail length was used to measure DNA damage. Welders had higher Cr and Ni content when compared with controls (Cr, 151.65 versus 17.86 micro g/l; Ni 132.39 versus 16.91 micro g/l; P &lt; 0.001). The results indicated that the welders had a larger mean comet tail length than that of the controls (mean +/- SD, 23.05 +/- 3.86 versus 8.94 +/- 3.16; P &lt; 0.001). In addition, the micronucleus test on buccal epithelial cells was carried out in a few randomly selected subjects. Welders showed a significant increase in micronucleated cells compared with controls (1.30 versus 0.32; P &lt; 0.001). Analysis of variance revealed that occupational exposure (P &lt; 0.05) had a significant effect on DNA mean tail length, whereas smoking and age had no significant effect on DNA damage. The current study suggested that chronic occupational exposure to Cr and Ni during welding could lead to increased levels of DNA damage."
1510407,Chiu et al. 2004,Genetic and cellular mechanisms in chromium and nickel carcinogenesis considering epidemiologic findings,"Genetic and environmental interactions determine cancer risks but some cancer incidence is primarily a result of inherited genetic deficits alone. Most cancers have an occupational, viral, nutritional, behavioral or iatrogenic etiology. Cancer can sometimes be controlled through broad public health interventions including industrial hygiene and engineering controls. Chromium and nickel are two human carcinogens associated with industrial exposures where public health measures apparently work. Carcinogenic mechanisms of these metals are examined by electron-spin-resonance-spectroscopy and somatic-mutation-and-recombination in Drosophila melanogaster in this report. Both metals primarily affect initiation processes in cancer development suggesting important theoretical approaches to prevention and followup.","Genetic and cellular mechanisms in chromium and nickel carcinogenesis considering epidemiologic findings Abs: Genetic and environmental interactions determine cancer risks but some cancer incidence is primarily a result of inherited genetic deficits alone. Most cancers have an occupational, viral, nutritional, behavioral or iatrogenic etiology. Cancer can sometimes be controlled through broad public health interventions including industrial hygiene and engineering controls. Chromium and nickel are two human carcinogens associated with industrial exposures where public health measures apparently work. Carcinogenic mechanisms of these metals are examined by electron-spin-resonance-spectroscopy and somatic-mutation-and-recombination in Drosophila melanogaster in this report. Both metals primarily affect initiation processes in cancer development suggesting important theoretical approaches to prevention and followup."
1510406,Leonard et al. 2004,"Metal-induced toxicity, carcinogenesis, mechanisms and cellular responses",,"Metal-induced toxicity, carcinogenesis, mechanisms and cellular responses Abs: "
1510405,Miyoshi et al. 2003,Use of Paramecium species in bioassays for environmental risk management: Determination of IC50 values for water pollutants,,Use of Paramecium species in bioassays for environmental risk management: Determination of IC50 values for water pollutants Abs: 
1510404,Seco et al. 2003,A study of the leachate toxicity of metal-containing solid wastes using Daphnia magna,,A study of the leachate toxicity of metal-containing solid wastes using Daphnia magna Abs: 
1510403,Kamaludeen et al. 2003,Microbial activity and phospholipid fatty acid pattern in long-term tannery waste-contaminated soil,,Microbial activity and phospholipid fatty acid pattern in long-term tannery waste-contaminated soil Abs: 
1510402,Manning and  Zuzel 2003,Comparison of types of cell death: apoptosis and necrosis,,Comparison of types of cell death: apoptosis and necrosis Abs: 
1510401,Deger et al. 2003,The prevalence of Eimeria species in goats in Van,,The prevalence of Eimeria species in goats in Van Abs: 
1510399,Devi et al. 2003,Immunomodulatory effects of Premna tomentosa extract against Cr (VI) induced toxicity in splenic lymphocytes - an in vitro study,,Immunomodulatory effects of Premna tomentosa extract against Cr (VI) induced toxicity in splenic lymphocytes - an in vitro study Abs: 
1510398,Dey et al. 2003,Effect of chromium on certain aspects of metabolic toxicities,,Effect of chromium on certain aspects of metabolic toxicities Abs: 
1510397,Abessa et al. 2003,Sensitivity of the amphipod Tiburonella viscana (Platyischnopidae) to K2CR2O7,,Sensitivity of the amphipod Tiburonella viscana (Platyischnopidae) to K2CR2O7 Abs: 
1510395,Balamurugan et al. 2002,Chromium(III)-induced apoptosis of lymphocytes: Death decision by ROS and Src-family tyrosine kinases,,Chromium(III)-induced apoptosis of lymphocytes: Death decision by ROS and Src-family tyrosine kinases Abs: 
1510393,Choi et al. 2002,"Multilevel effects of sublethal fenitrothion exposure in Chironomus riparius mg. (Diptera, Chironomidae) larvae",,"Multilevel effects of sublethal fenitrothion exposure in Chironomus riparius mg. (Diptera, Chironomidae) larvae Abs: "
1510392,Arslan et al. 2002,The frequency of Eimeriidae species in the domestic geese in Kars province of Turkey,,The frequency of Eimeriidae species in the domestic geese in Kars province of Turkey Abs: 
1510391,Dahbi et al. 2002,Removal of trivalent chromium from tannery waste waters using bone charcoal,,Removal of trivalent chromium from tannery waste waters using bone charcoal Abs: 
1510389,Manygoats et al. 2002,Ultrastructural damage in chromium picolinate-treated cells: a TEM study,,Ultrastructural damage in chromium picolinate-treated cells: a TEM study Abs: 
1510386,Aly and  Donya 2002,In vivo antimutagenic effect of vitamins C and E against rifampicin-induced chromosome aberrations in mouse bone-marrow cells,,In vivo antimutagenic effect of vitamins C and E against rifampicin-induced chromosome aberrations in mouse bone-marrow cells Abs: 
1510385,Chardin et al. 2002,Chromium speciation in bacterial culture medium by combining strong anion exchange liquid chromatography with inductively coupled plasma mass spectrometry. Application to the reduction of CR(VI) by sulfate-reducing bacteria,,Chromium speciation in bacterial culture medium by combining strong anion exchange liquid chromatography with inductively coupled plasma mass spectrometry. Application to the reduction of CR(VI) by sulfate-reducing bacteria Abs: 
1510384,Dixit et al. 2002,Chromium ions inactivate electron transport and enhance superoxide generation in vivo in pea (Pisum sativum L. cv. Azad) root mitochondria,,Chromium ions inactivate electron transport and enhance superoxide generation in vivo in pea (Pisum sativum L. cv. Azad) root mitochondria Abs: 
1510382,Geetha et al. 2002,Anti-oxidant and immunomodulatory properties of seabuckthorn (Hippophae rhamnoides) - an in vitro study,,Anti-oxidant and immunomodulatory properties of seabuckthorn (Hippophae rhamnoides) - an in vitro study Abs: 
1510381,Chen et al. 2002,Use of inhalable Cr+6 exposures to characterize urinary chromium concentrations in plating industry workers,,Use of inhalable Cr+6 exposures to characterize urinary chromium concentrations in plating industry workers Abs: 
1510377,Carrillo-Morales et al. 2001,Removal of metal ions from aqueous solution by adsorption on the natural adsorbent CACMM2,,Removal of metal ions from aqueous solution by adsorption on the natural adsorbent CACMM2 Abs: 
1510375,Sahu et al. 2001,Pro-oxidant effects of the flavonoid myricetin on rat hepatocytes in culture,,Pro-oxidant effects of the flavonoid myricetin on rat hepatocytes in culture Abs: 
1510373,Seoane et al. 2000,Mechanisms involved in the induction of aneuploidy: The significance of chromosome loss,,Mechanisms involved in the induction of aneuploidy: The significance of chromosome loss Abs: 
1510371,Sag and  Aktay 2001,Application of equilibrium and mass transfer models to dynamic removal of Cr(VI) ions by Chitin in packed column reactor,,Application of equilibrium and mass transfer models to dynamic removal of Cr(VI) ions by Chitin in packed column reactor Abs: 
1510369,Stasinakis et al. 2001,Toxicity of organotin compounds to activated sludge,"Inhibition of respiration rate of activated sludge heterotrophic microorganisms was determined for tributyltin (TBT), dibutyltin (DBT), monobutyltin (MBT), and triphenyltin (TPhT). TBT, DBT, and TPhT exhibit similar acute toxicity to activated sludge, while MBT is less toxic. The effect of various experimental parameters, such as sludge age, concentrations of suspended solids, and exposure time, on toxicity was investigated. An increase in sludge age or in the concentration of suspended solids reduces the observed inibition. Longer exposure seems to increase the inhibition of TBT, DBT, and TPhT during the first hours of exposure, while later the inhibition remains constant. In the case of MBT, 24 h after exposure, the respiration rate was similar to that of the control biomass.","Toxicity of organotin compounds to activated sludge Abs: Inhibition of respiration rate of activated sludge heterotrophic microorganisms was determined for tributyltin (TBT), dibutyltin (DBT), monobutyltin (MBT), and triphenyltin (TPhT). TBT, DBT, and TPhT exhibit similar acute toxicity to activated sludge, while MBT is less toxic. The effect of various experimental parameters, such as sludge age, concentrations of suspended solids, and exposure time, on toxicity was investigated. An increase in sludge age or in the concentration of suspended solids reduces the observed inibition. Longer exposure seems to increase the inhibition of TBT, DBT, and TPhT during the first hours of exposure, while later the inhibition remains constant. In the case of MBT, 24 h after exposure, the respiration rate was similar to that of the control biomass."
1510367,Jie et al. 2001,Novel azido fatty acid ester derivatives from conjugated C-18 enynoate,,Novel azido fatty acid ester derivatives from conjugated C-18 enynoate Abs: 
1510366,Davies et al. 2001,Mycorrhizal fungi enhance accumulation and tolerance of chromium in sunflower (Helianthus annuus),,Mycorrhizal fungi enhance accumulation and tolerance of chromium in sunflower (Helianthus annuus) Abs: 
1510365,Michailova et al. 2001,"Genotoxic effects of chromium on polytene chromosomes of Chironomus riparius Meigen 1804 (Diptera, Chironomidae)",,"Genotoxic effects of chromium on polytene chromosomes of Chironomus riparius Meigen 1804 (Diptera, Chironomidae) Abs: "
1510363,Muter et al. 2001,Interrelations of the yeast Candida utilis and Cr(VI): metal reduction and its distribution in the cell and medium,,Interrelations of the yeast Candida utilis and Cr(VI): metal reduction and its distribution in the cell and medium Abs: 
1510359,Maitra et al. 2001,Differential effects of mitomycin D and doxorubicin on P-glycoprotein expression,,Differential effects of mitomycin D and doxorubicin on P-glycoprotein expression Abs: 
1510357,Elbetieha et al. 2001,Effects of long-term exposure to manganese chloride on fertility of male and female mice,,Effects of long-term exposure to manganese chloride on fertility of male and female mice Abs: 
1510355,Wang and  Dei 2001,Influences of phosphate and silicate on Cr(VI) and Se(IV) accumulation in marine phytoplankton,,Influences of phosphate and silicate on Cr(VI) and Se(IV) accumulation in marine phytoplankton Abs: 
1510353,Prokisch et al. 2000,Yttrium normalisation: A new tool for detection of chromium contamination in soil samples,,Yttrium normalisation: A new tool for detection of chromium contamination in soil samples Abs: 
1510352,Abessa et al. 1998,Use of the burrowing amphipod Tiburonella viscana as a tool in marine sediments contamination assessment,,Use of the burrowing amphipod Tiburonella viscana as a tool in marine sediments contamination assessment Abs: 
1510351,Tsvetnenko et al. 2000,Development of marine sediment reworker tests with Western Australian species for toxicity assessment of drilling mud,,Development of marine sediment reworker tests with Western Australian species for toxicity assessment of drilling mud Abs: 
1510350,Natale et al. 2000,"Effect of Cr(VI) on early life stages of three species of hylid frogs (Amphibia, anura) from South America",,"Effect of Cr(VI) on early life stages of three species of hylid frogs (Amphibia, anura) from South America Abs: "
1510349,Fochtman et al. 2000,"The use of conventional bioassays, microbiotests, and some ""rapid"" methods in the selection of an optimal test battery for the assessment of pesticides toxicity",,"The use of conventional bioassays, microbiotests, and some ""rapid"" methods in the selection of an optimal test battery for the assessment of pesticides toxicity Abs: "
1510347,Mukhopadhyay and  Aery 2000,Effect of Cr (III) and Cr (VI) on the growth and physiology of Triticum aestivum plants during early seedling growth,,Effect of Cr (III) and Cr (VI) on the growth and physiology of Triticum aestivum plants during early seedling growth Abs: 
1510346,Coeurdassier et al. 2000,Dose-dependent growth inhibition and bioaccumulation of hexavalent chromium in land snail Helix aspersa aspersa,,Dose-dependent growth inhibition and bioaccumulation of hexavalent chromium in land snail Helix aspersa aspersa Abs: 
1510344,Salacinski and  O'Brien 2000,Evidence that the reactions of nickel in the presence of vitamin C do not produce toxic oxygen intermediates such as hydroxyl but ascorbate and carbon radicals,,Evidence that the reactions of nickel in the presence of vitamin C do not produce toxic oxygen intermediates such as hydroxyl but ascorbate and carbon radicals Abs: 
1510343,Ram et al. 2000,Effect of Kombucha tea on chromate(VI)-induced oxidative stress in albino rats,,Effect of Kombucha tea on chromate(VI)-induced oxidative stress in albino rats Abs: 
1510339,Appenroth et al. 2000,Kinetics of chromium(V) formation and reduction in fronds of the duckweed Spirodela polyrhiza - a low frequency EPR study,,Kinetics of chromium(V) formation and reduction in fronds of the duckweed Spirodela polyrhiza - a low frequency EPR study Abs: 
1510338,Hojo et al. 2000,Enhancement of lipid peroxidation by chromium(IV) and chromium(V) is remarkable compared to that by chromium(VI) and is effectively suppressed by scavengers of reactive oxygen species,,Enhancement of lipid peroxidation by chromium(IV) and chromium(V) is remarkable compared to that by chromium(VI) and is effectively suppressed by scavengers of reactive oxygen species Abs: 
1510337,Choi et al. 2000,"Effects of physical (Hypoxia, Hyperoxia) and chemical (potassium dichromate, fenitrothion) stress on antioxidant enzyme activities in Chironomus riparius Mg. (Diptera, Chironomidae) larvae: Potential biomarkers",,"Effects of physical (Hypoxia, Hyperoxia) and chemical (potassium dichromate, fenitrothion) stress on antioxidant enzyme activities in Chironomus riparius Mg. (Diptera, Chironomidae) larvae: Potential biomarkers Abs: "
1510336,Howell et al. 2000,Comparison of murine assays for the identification of chemical sensitizers,,Comparison of murine assays for the identification of chemical sensitizers Abs: 
1510334,Sugden 1999,Formation of modified cleavage termini from the reaction of chromium(V) with DNA,,Formation of modified cleavage termini from the reaction of chromium(V) with DNA Abs: 
1510333,Hojo et al. 1999,"Comparison of susceptibility of liver and kidney to lipid peroxidation induction by Cr(IV), Cr(V) and Cr(VI) compounds","Chromium(VI) compounds, potent carcinogens, are known to induce lipid peroxidation. However, it is not clear how Cr(VI) induces lipid peroxidation. It has been proposed that Cr intermediates such as Cr(IV) and Cr(V), possibly generated during the metabolic reduction of Cr(VI) to Cr(III), may be responsible for the Cr(VI)-induced DNA damage and cancer. In this article, in order to clarify the mechanism by which Cr(VI) enhances lipid peroxidation, mouse liver or kidney homogenate was incubated with Cr(III), Cr(IV), Cr(V) and Cr(VI) compounds. Our results are as follows : (i) lipids in liver homogenate are peroxidized more remarkably than those in kidney homogenate after being treated with Cr(IV), Cr(V) and Cr(VI) compounds; (ii) lipid peroxidation induction by Cr(IV) and Cr(V) compounds is more effective in both liver and kidney homogenates than that by the Cr(VI) compound; (iii) the extent of lipid peroxidation induced by the Cr compounds is significantly correlated between liver and kidney homogenates. These results suggest the possible participation of Cr(IV) and Cr(V) in Cr(VI)-enhanced lipid peroxidation.","Comparison of susceptibility of liver and kidney to lipid peroxidation induction by Cr(IV), Cr(V) and Cr(VI) compounds Abs: Chromium(VI) compounds, potent carcinogens, are known to induce lipid peroxidation. However, it is not clear how Cr(VI) induces lipid peroxidation. It has been proposed that Cr intermediates such as Cr(IV) and Cr(V), possibly generated during the metabolic reduction of Cr(VI) to Cr(III), may be responsible for the Cr(VI)-induced DNA damage and cancer. In this article, in order to clarify the mechanism by which Cr(VI) enhances lipid peroxidation, mouse liver or kidney homogenate was incubated with Cr(III), Cr(IV), Cr(V) and Cr(VI) compounds. Our results are as follows : (i) lipids in liver homogenate are peroxidized more remarkably than those in kidney homogenate after being treated with Cr(IV), Cr(V) and Cr(VI) compounds; (ii) lipid peroxidation induction by Cr(IV) and Cr(V) compounds is more effective in both liver and kidney homogenates than that by the Cr(VI) compound; (iii) the extent of lipid peroxidation induced by the Cr compounds is significantly correlated between liver and kidney homogenates. These results suggest the possible participation of Cr(IV) and Cr(V) in Cr(VI)-enhanced lipid peroxidation."
1510330,Tokuda et al. 1999,"Pilot plant test for removal of organic matter, N and P from whisky pot ale",,"Pilot plant test for removal of organic matter, N and P from whisky pot ale Abs: "
1510328,Ozer et al. 1999,Application of Freundlich and Langmuir models to multistage purification process to remove heavy metal ions by using Schizomeris leibleinii,,Application of Freundlich and Langmuir models to multistage purification process to remove heavy metal ions by using Schizomeris leibleinii Abs: 
1510324,Srivastava et al. 1999,Studies on mobilization of chromium with reference to its plant availability - Role of organic acids,,Studies on mobilization of chromium with reference to its plant availability - Role of organic acids Abs: 
1510322,Signorella et al. 1999,The relative ability of aldoses and deoxyaldoses to reduce Cr-VI and Cr-V. A comparative kinetic and mechanistic study,,The relative ability of aldoses and deoxyaldoses to reduce Cr-VI and Cr-V. A comparative kinetic and mechanistic study Abs: 
1510321,Carson et al. 1999,Inconsistent detection of Histoplasma capsulatum with periodic acid oxidation in the Grocott methenamine-silver nitrate (CMS) fungus stain,,Inconsistent detection of Histoplasma capsulatum with periodic acid oxidation in the Grocott methenamine-silver nitrate (CMS) fungus stain Abs: 
1510319,Srivastava et al. 1998,Fate of trivalent chromium in presence of organic acids: a hydroponic study on the tomato plant,,Fate of trivalent chromium in presence of organic acids: a hydroponic study on the tomato plant Abs: 
1510317,Bose et al. 1999,Oxidative damage of DNA by chromium(V) complexes: relative importance of base versus sugar oxidation,"Chromium(V)-mediated oxidative damage of deoxyribonucleic acids was investigated at neutral pH in aqueous solution by utilizing bis(2-ethyl-2-hydroxybutanato)oxochromate(V) (I) and bis(hydroxyethyl)amino-tris(hydroxymethyl)methane)oxochromate(V) (II). Single-stranded and double-stranded (ds) calf thymus and human placenta DNA, as well as two oligomers, 5'-GATCTAGTAGGAGGACAAATAGTGTPTG-3' and 5'-GATCCAAGCAAACACTATTTGTCCTCCTACTA-3', were reacted with the chromium(V) complexes. Most products were separated and characterized by chromatographic and spectroscopic methods, Polyacrylamide gel electrophoresis experiments reveal more damage at G sites in comparison to other bases. Three primary oxidation products, 5-methylene-2-furanone (5-MF), furfural and 8-oxo-2'-deoxyguanosine, were characterized, A minor product, which appears to be thymine propenal, was also observed. The dsDNA produces more furfural than furanone, The formation of these two products resulted from hydrogen abstraction dr hydride transfer from C1' and C5' positions of the ribose to the oxo-chromium(V) center. Since no enhancements of these products (except propenal) were observed in the presence of oxygen, mechanisms pertaining to the participation of activated oxygen species may be ruled out. The oxidation of the G base is most likely associated with an oxygen atom transfer from the oxo-metallates to the double bond between C8 and N7 of the purine ring. The formation of the propenal may be associated with an oxygen-activated species, since a marginal enhancement of this product was observed in the presence of oxygen, The formation of furfural in higher abundance over 5-MF for dsDNA was attributed to the ease of hydrogen abstraction (or hydride transfer) from the C5' compared to C1' position of the ribose within a Cr(V)-DNA intermediate in which the metal center is bound to the phosphate diester moiety.","Oxidative damage of DNA by chromium(V) complexes: relative importance of base versus sugar oxidation Abs: Chromium(V)-mediated oxidative damage of deoxyribonucleic acids was investigated at neutral pH in aqueous solution by utilizing bis(2-ethyl-2-hydroxybutanato)oxochromate(V) (I) and bis(hydroxyethyl)amino-tris(hydroxymethyl)methane)oxochromate(V) (II). Single-stranded and double-stranded (ds) calf thymus and human placenta DNA, as well as two oligomers, 5'-GATCTAGTAGGAGGACAAATAGTGTPTG-3' and 5'-GATCCAAGCAAACACTATTTGTCCTCCTACTA-3', were reacted with the chromium(V) complexes. Most products were separated and characterized by chromatographic and spectroscopic methods, Polyacrylamide gel electrophoresis experiments reveal more damage at G sites in comparison to other bases. Three primary oxidation products, 5-methylene-2-furanone (5-MF), furfural and 8-oxo-2'-deoxyguanosine, were characterized, A minor product, which appears to be thymine propenal, was also observed. The dsDNA produces more furfural than furanone, The formation of these two products resulted from hydrogen abstraction dr hydride transfer from C1' and C5' positions of the ribose to the oxo-chromium(V) center. Since no enhancements of these products (except propenal) were observed in the presence of oxygen, mechanisms pertaining to the participation of activated oxygen species may be ruled out. The oxidation of the G base is most likely associated with an oxygen atom transfer from the oxo-metallates to the double bond between C8 and N7 of the purine ring. The formation of the propenal may be associated with an oxygen-activated species, since a marginal enhancement of this product was observed in the presence of oxygen, The formation of furfural in higher abundance over 5-MF for dsDNA was attributed to the ease of hydrogen abstraction (or hydride transfer) from the C5' compared to C1' position of the ribose within a Cr(V)-DNA intermediate in which the metal center is bound to the phosphate diester moiety."
1510316,Khangarot et al. 1999,"Effects of chromium on humoral and cell-mediated immune responses and host resistance to disease in a freshwater catfish, Saccobranchus fossilis (Bloch)",,"Effects of chromium on humoral and cell-mediated immune responses and host resistance to disease in a freshwater catfish, Saccobranchus fossilis (Bloch) Abs: "
1510315,Grillo et al. 1999,Protective effect of butylated hydroxytoluene (BHT) against the clastogenic activity of cadmium chloride and potassium dichromate in Chinese hamster ovary cells,"The effect of butylated hydroxytoluene (BHT), a widely used food additive, on chromosomal alterations induced by cadmium chloride (CC) and potassium dichromate (PD) in Chinese hamster ovary (CHO) cells was studied both at metaphase and anaphase-telophase. CHO cells were cultured for 15-16 h in the presence of PD (6.0, 9.0 or 12.0 mM), BHT (1.0 mg/ml), or PD plus BHT as well as CC (0.5, 1.0 and 2.0 mM), BHT or CC plus BHT for the analysis of chromosomal aberrations. To perform the anaphase-telophase test, cells were cultured in cover glasses and treated 8 h before fixation with the same chemicals. An extra dose of CC (4 mM) was used in this test. Both metal salts significantly increased chromosomal aberration frequencies in relation to untreated controls, and to DMSO- and BHT-treated cells. Post-treatment with BHT decreased the yield of chromosomal damage in relation to treatments performed with CC and PD. However, chromosomal aberration frequencies were significantly higher than those of the controls. In the anaphase-telophase test, CC significantly increased the yield of lagging chromosomes with the four doses employed and the frequency of lagging fragments with the highest dose. In combined treatments of CC and BHT, frequencies of the two types of alterations decreased significantly in relation to the cells treated with CC alone. No significant variation was found in the frequencies of chromatin bridges. Significant increases of numbers of chromatin bridges, lagging chromosomes and lagging fragments were found in cells treated with PD. The protective effect of BHT in combined treatments was evidenced by the significant decrease of chromatid bridges and lagging chromosomes in relation to PD-treated cells. Whereas BHT is able to induce chromosomal damage, it can also protect against oxidative damage induced by other genotoxicants.","Protective effect of butylated hydroxytoluene (BHT) against the clastogenic activity of cadmium chloride and potassium dichromate in Chinese hamster ovary cells Abs: The effect of butylated hydroxytoluene (BHT), a widely used food additive, on chromosomal alterations induced by cadmium chloride (CC) and potassium dichromate (PD) in Chinese hamster ovary (CHO) cells was studied both at metaphase and anaphase-telophase. CHO cells were cultured for 15-16 h in the presence of PD (6.0, 9.0 or 12.0 mM), BHT (1.0 mg/ml), or PD plus BHT as well as CC (0.5, 1.0 and 2.0 mM), BHT or CC plus BHT for the analysis of chromosomal aberrations. To perform the anaphase-telophase test, cells were cultured in cover glasses and treated 8 h before fixation with the same chemicals. An extra dose of CC (4 mM) was used in this test. Both metal salts significantly increased chromosomal aberration frequencies in relation to untreated controls, and to DMSO- and BHT-treated cells. Post-treatment with BHT decreased the yield of chromosomal damage in relation to treatments performed with CC and PD. However, chromosomal aberration frequencies were significantly higher than those of the controls. In the anaphase-telophase test, CC significantly increased the yield of lagging chromosomes with the four doses employed and the frequency of lagging fragments with the highest dose. In combined treatments of CC and BHT, frequencies of the two types of alterations decreased significantly in relation to the cells treated with CC alone. No significant variation was found in the frequencies of chromatin bridges. Significant increases of numbers of chromatin bridges, lagging chromosomes and lagging fragments were found in cells treated with PD. The protective effect of BHT in combined treatments was evidenced by the significant decrease of chromatid bridges and lagging chromosomes in relation to PD-treated cells. Whereas BHT is able to induce chromosomal damage, it can also protect against oxidative damage induced by other genotoxicants."
1510314,Stoecker 1999,"Chromium absorption, safety, and toxicity",,"Chromium absorption, safety, and toxicity Abs: "
1510311,Mock et al. 1999,Measurement of circulating red cell volume using biotin-labeled red cells: validation against Cr-51-labeled red cells,,Measurement of circulating red cell volume using biotin-labeled red cells: validation against Cr-51-labeled red cells Abs: 
1510310,Farre et al. 1998,Different factors affecting the analysis of inorganic anions at low microgram per litre levels by capillary zone electrophoresis with electrokinetic injection,,Different factors affecting the analysis of inorganic anions at low microgram per litre levels by capillary zone electrophoresis with electrokinetic injection Abs: 
1510309,Kadiiska et al. 1998,Identification of free radical formation and F-2-isoprostanes in vivo by acute Cr(VI) poisoning,,Identification of free radical formation and F-2-isoprostanes in vivo by acute Cr(VI) poisoning Abs: 
1510308,Carroll et al. 1998,"Sterol synthesis, synthesis of 3 beta-hydroxy-25,26,26,26,27,27,27-heptafluorocholest-5-en-7-one and its effects on HMG-CoA reductase activity in Chinese hamster ovary cells, on ACAT activity in rat jejunal microsomes, and serum cholesterol levels in rats",,"Sterol synthesis, synthesis of 3 beta-hydroxy-25,26,26,26,27,27,27-heptafluorocholest-5-en-7-one and its effects on HMG-CoA reductase activity in Chinese hamster ovary cells, on ACAT activity in rat jejunal microsomes, and serum cholesterol levels in rats Abs: "
1510307,Zayed et al. 1998,"Chromium accumulation, translocation and chemical speciation in vegetable crops",,"Chromium accumulation, translocation and chemical speciation in vegetable crops Abs: "
1510303,Graf et al. 1998,Antigenotoxicity studies in Drosophila melanogaster,,Antigenotoxicity studies in Drosophila melanogaster Abs: 
1510301,Bundy and  Berzins 1998,Differential pulse polarographic analysis of lead and chromium content in Louisiana waters,,Differential pulse polarographic analysis of lead and chromium content in Louisiana waters Abs: 
1510300,Shi et al. 1998,Cr(III)-mediated hydroxyl radical generation via Haber-Weiss cycle,,Cr(III)-mediated hydroxyl radical generation via Haber-Weiss cycle Abs: 
1510299,Godoy et al. 1998,An alternative method for the determination of excess Pb-210 in sediments,,An alternative method for the determination of excess Pb-210 in sediments Abs: 
1510296,Gianello et al. 1998,Occupational exposure to chromium - An assessment of environmental pollution levels and biological monitoring of exposed workers,,Occupational exposure to chromium - An assessment of environmental pollution levels and biological monitoring of exposed workers Abs: 
1510295,Collins et al. 1997,Liquid chromatographic separation of aqueous species of Cr(VI) and Cr(III),,Liquid chromatographic separation of aqueous species of Cr(VI) and Cr(III) Abs: 
1510248,Shi 2006,Metal-Induced Oxidative Stress And Cellular Responses,"Reactive oxygen species (ROS) generated by metals play an important role in the etiology of various diseases and cancers. Metals generate ROS by two general pathways. One is direct interaction of metals with cellular molecules without involvement of signaling transduction. For example, flavenzymes reduce Cr(VI) to Cr(V) in the presence of NAD(P)H; oxygen is reduced to superoxide radical that generates hydrogen peroxide by dismutation; Cr(VI) also reacts with hydrogen to generate hydroxyl radicals by a Fenton-like reaction. Alternatively, metals may generate ROS by stimulation of cells; this involves expression of NADPH oxidase by various signal molecules. Metals may induce various cellular responses by ROS mediated reactions. For example, Cr(VI) may activate MAPKs and their down stream targets, such as NF-kappaB and AP-1. NF-kappaB inhibits of Cr(VI)-induced cell death. Inhibition of NF-kappaB by IKKbeta-KM or IKKbeta deficiency results in spontaneous cleavage of Bcl-xL antiapoptotic protein due to elevated caspase-3 activity. Exogenous antiapoptotic proteins (cIAP1), a caspase inhibitor, partially inhibits Cr(VI)-induced cell death; thus caspases are involved in Cr(VI)-induced cell death. In response to Cr(VI), p53 protein is phosphorylated at Ser15 and acetylated at Lys382. ERK phosphorylates p53 at Ser15 site. Via ERK and p38, Cr(VI) also upregulates p21 and cdc2 and causes degradation of cdc25C, leading to growth arrest at G2/M. Specific ROS affect specific MAPKs and cell growth regulatory proteins with different potencies. Cr(VI) induces hypoxia-inducible factor-1 (HIF-1) activity by specific expression of HIF-1alpha but not HIF-1beta subunit and increases vascular endothelial growth factor (VEGF) expression. p38 signaling is required for Cr(VI)- induced HIF-alpha expression, but PI3-K and ERK are not required for Cr(VI)-induced HIF-1 expression. Hydrogen peroxide is responsible for HIF-1 induction and VEGF expression. By ROS-mediated mechanisms, As, Ni and V also activate MAPKs and other oxidative responsive proteins to induce cellular responses, such as activation of PI3-K/Akt pathway, NF-kappaB, AP-1, p53, nuclear factor of activated T cells (NFAT), HIF-1, cell cycle arrest, and apoptosis.","Metal-Induced Oxidative Stress And Cellular Responses Abs: Reactive oxygen species (ROS) generated by metals play an important role in the etiology of various diseases and cancers. Metals generate ROS by two general pathways. One is direct interaction of metals with cellular molecules without involvement of signaling transduction. For example, flavenzymes reduce Cr(VI) to Cr(V) in the presence of NAD(P)H; oxygen is reduced to superoxide radical that generates hydrogen peroxide by dismutation; Cr(VI) also reacts with hydrogen to generate hydroxyl radicals by a Fenton-like reaction. Alternatively, metals may generate ROS by stimulation of cells; this involves expression of NADPH oxidase by various signal molecules. Metals may induce various cellular responses by ROS mediated reactions. For example, Cr(VI) may activate MAPKs and their down stream targets, such as NF-kappaB and AP-1. NF-kappaB inhibits of Cr(VI)-induced cell death. Inhibition of NF-kappaB by IKKbeta-KM or IKKbeta deficiency results in spontaneous cleavage of Bcl-xL antiapoptotic protein due to elevated caspase-3 activity. Exogenous antiapoptotic proteins (cIAP1), a caspase inhibitor, partially inhibits Cr(VI)-induced cell death; thus caspases are involved in Cr(VI)-induced cell death. In response to Cr(VI), p53 protein is phosphorylated at Ser15 and acetylated at Lys382. ERK phosphorylates p53 at Ser15 site. Via ERK and p38, Cr(VI) also upregulates p21 and cdc2 and causes degradation of cdc25C, leading to growth arrest at G2/M. Specific ROS affect specific MAPKs and cell growth regulatory proteins with different potencies. Cr(VI) induces hypoxia-inducible factor-1 (HIF-1) activity by specific expression of HIF-1alpha but not HIF-1beta subunit and increases vascular endothelial growth factor (VEGF) expression. p38 signaling is required for Cr(VI)- induced HIF-alpha expression, but PI3-K and ERK are not required for Cr(VI)-induced HIF-1 expression. Hydrogen peroxide is responsible for HIF-1 induction and VEGF expression. By ROS-mediated mechanisms, As, Ni and V also activate MAPKs and other oxidative responsive proteins to induce cellular responses, such as activation of PI3-K/Akt pathway, NF-kappaB, AP-1, p53, nuclear factor of activated T cells (NFAT), HIF-1, cell cycle arrest, and apoptosis."
1510247,Miller et al. 2006,Dietary Hexavalent Chromium Exposure Causes DNA-Protein Crosslink Formation In Erythrocytes Of Largemouth Bass,"Hexavalent chromium (Cr6+) is known to cause DNA-protein crosslink (DPX)formation in cell lines and in liver cells of rats exposed by drinking water. This project was designed to determine if DPXs could accumulate in minnows following waterborne exposure, then accumulate in a predatory fish that fed upon them. Exposure of 2-3? fathead minnows to 2 ppm Cr6+ in tank water at 15 degrees C led to significant DPX formation in erythrocytes, with over 150 and 200% elevations above background levels at 3-4 days, respectively (p<0.05). Largemouth bass exposed similarly were found to have 62% elevation of DPX levels above controls after 4 days. However, when largemouth bass were fed a 21 day diet of only minnows which had been previously exposed to 2 ppm Cr6+ for 3-4 days, there was no significant difference in DPX levels compared to bass fed control (unexposed) minnows. In contrast, when largemouth bass were fed a diet of dead minnows injected with 20 ug Cr6+ for 5 days, a significant (p<0.01) increase of DPXs in erythrocytes was observed, with 80% elevation above bass fed minnows injected only with saline. This study provides evidence that DPX formation occurs in erythrocytes of fathead minnows exposed under controlled conditions to waterborne Cr6+ at 2 ppm concentrations, which is at or below concentrations previously assigned no observable effect levels. Furthermore, it appears that both waterborne and high dose dietary exposure to Cr6+ can lead to DPX formation in erythrocytes of predatory fish species such as bass. However, it is unlikely that a bio-concentration of chromiuminduced DPXs in the food chain is a major concern at these low ppm levels of exposure. Cr6+ accumulated by minnows is most likely reduced to Cr3+, which cannot be absorbed following ingestion of minnows by predatory fish. Further, it may be difficult to achieve dietary Cr6+ levels high enough to elicit DPXs in predatory fish under most environmental exposure scenarios.","Dietary Hexavalent Chromium Exposure Causes DNA-Protein Crosslink Formation In Erythrocytes Of Largemouth Bass Abs: Hexavalent chromium (Cr6+) is known to cause DNA-protein crosslink (DPX)formation in cell lines and in liver cells of rats exposed by drinking water. This project was designed to determine if DPXs could accumulate in minnows following waterborne exposure, then accumulate in a predatory fish that fed upon them. Exposure of 2-3? fathead minnows to 2 ppm Cr6+ in tank water at 15 degrees C led to significant DPX formation in erythrocytes, with over 150 and 200% elevations above background levels at 3-4 days, respectively (p<0.05). Largemouth bass exposed similarly were found to have 62% elevation of DPX levels above controls after 4 days. However, when largemouth bass were fed a 21 day diet of only minnows which had been previously exposed to 2 ppm Cr6+ for 3-4 days, there was no significant difference in DPX levels compared to bass fed control (unexposed) minnows. In contrast, when largemouth bass were fed a diet of dead minnows injected with 20 ug Cr6+ for 5 days, a significant (p<0.01) increase of DPXs in erythrocytes was observed, with 80% elevation above bass fed minnows injected only with saline. This study provides evidence that DPX formation occurs in erythrocytes of fathead minnows exposed under controlled conditions to waterborne Cr6+ at 2 ppm concentrations, which is at or below concentrations previously assigned no observable effect levels. Furthermore, it appears that both waterborne and high dose dietary exposure to Cr6+ can lead to DPX formation in erythrocytes of predatory fish species such as bass. However, it is unlikely that a bio-concentration of chromiuminduced DPXs in the food chain is a major concern at these low ppm levels of exposure. Cr6+ accumulated by minnows is most likely reduced to Cr3+, which cannot be absorbed following ingestion of minnows by predatory fish. Further, it may be difficult to achieve dietary Cr6+ levels high enough to elicit DPXs in predatory fish under most environmental exposure scenarios."
1510245,Perry et al. 2006,Persistence Of DNA-Protein Cross-Links In Erythrocytes Of Channel Catfish After Acute Hexavalent Chromium Exposure,"DNA-protein crosslinks (DPXs) have been used previously as a potential biomarker for occupational exposure to a hexavalent chromium (Cr6+), under a variety of exposure scenarios. Cr6+ is found ubiquitously in many industrial waterways, causing considerable concern about human health and environmental impact. The accumulation of Cr6+ in river sediments has raised issues about possible of toxicity to fish species feeding in such areas. To be useful as an environmental biomarker, adducts such as DPXs must be biologically stable for some time after chemical exposure. It has been shown recently that Cr6+ induced DPXs are repaired in mammalian cells, yet no information exists about their formation and stability in fish under controlled conditions. We have addressed this issue by exposing juvenile channel catfish (2-4?) to Cr6+ at 2 ppm in tank water for up to 15 days, and removing some fish from the tank and placing them back in purified water alone. DPXs in erythrocytes from exposed catfish were monitored over this time period to determine their biologic stability. Catfish exposed for 4, 7, 10 and 15 days accumulated significantly higher levels of DPXs above time zero and day 15 controls, with 48, 73, 119 and 801% elevations, respectively (p<0.05). When catfish were exposed to Cr6+ for 10 days, then placed in purified water (no Cr6+), DPXs continued to increase to over the next 5 days to 419% above 15 day controls. This represents a 250% increase above levels seen at day 10 (when removed from Cr6+). This suggests that DPX formation may occur for a significant period of time after initial uptake of Cr6+. It may be that Cr6+ is reduced intracellularly and sequestered as Cr3+ adducts on the DNA alone, subsequent reaction with chromatin proteins would form additional DPXs. Available data suggest that DPXs are biologically stable and detectable for several weeks.","Persistence Of DNA-Protein Cross-Links In Erythrocytes Of Channel Catfish After Acute Hexavalent Chromium Exposure Abs: DNA-protein crosslinks (DPXs) have been used previously as a potential biomarker for occupational exposure to a hexavalent chromium (Cr6+), under a variety of exposure scenarios. Cr6+ is found ubiquitously in many industrial waterways, causing considerable concern about human health and environmental impact. The accumulation of Cr6+ in river sediments has raised issues about possible of toxicity to fish species feeding in such areas. To be useful as an environmental biomarker, adducts such as DPXs must be biologically stable for some time after chemical exposure. It has been shown recently that Cr6+ induced DPXs are repaired in mammalian cells, yet no information exists about their formation and stability in fish under controlled conditions. We have addressed this issue by exposing juvenile channel catfish (2-4?) to Cr6+ at 2 ppm in tank water for up to 15 days, and removing some fish from the tank and placing them back in purified water alone. DPXs in erythrocytes from exposed catfish were monitored over this time period to determine their biologic stability. Catfish exposed for 4, 7, 10 and 15 days accumulated significantly higher levels of DPXs above time zero and day 15 controls, with 48, 73, 119 and 801% elevations, respectively (p<0.05). When catfish were exposed to Cr6+ for 10 days, then placed in purified water (no Cr6+), DPXs continued to increase to over the next 5 days to 419% above 15 day controls. This represents a 250% increase above levels seen at day 10 (when removed from Cr6+). This suggests that DPX formation may occur for a significant period of time after initial uptake of Cr6+. It may be that Cr6+ is reduced intracellularly and sequestered as Cr3+ adducts on the DNA alone, subsequent reaction with chromatin proteins would form additional DPXs. Available data suggest that DPXs are biologically stable and detectable for several weeks."
1510244,Mellinger et al. 2006,DNA-Protein Crosslinks As A Potential Biomonitor Of Hexavalent Chromium Exposure In Rainbow Trout,"Hexavalent chromium (Cr6+) is found ubiquitously in many industrial waterways, as a result of mining, leather, steel, chrome plating and dye industries. Cr6+ has been demonstrated to cause DNA-protein crosslink (DPX) formation in developing sea urchin embryos, yet little is known about vertebrate aquatic wildlife. Fish erythrocytes are nucleated and represent a convenient tissue for studying DNA damage in vivo. Using an SDS/KCl precipitation technique, we attempted to determine if Cr6+ causes DPXs in erythrocytes of live trout at exposure levels which may be environmentally relevant. Fingerling trout (2-4?) were exposed to increasing [Cr6+] for 4 days at 15 degrees C. Dose dependent increases in DPXs were found at concentrations above 1 ppm, with 44, 116 (p<0.05), and 140% (p<0.01) above control levels at 1, 2 and 4 ppm, respectively. Next, fingerlings were exposed to 2 ppm Cr6+ in tank water for up to 21 days at 15 degrees C. Significant, time-dependent elevations in DPXs were observed in Cr6+ treated trout with 44, 92 and 201% increases above control DPX levels at 4, 7 and 21 days of exposure, respectively (p<0.05). Effect of body size on Cr6+-induced DPXs studied with four size groups of juvenile trout (2- 4?, 4-6?, 6-8? and 8-10?), housed together in a 55 gallon tank. Trout were exposed with an initial 2 ppm dose at time zero, and subsequent additions of 1 ppm at 24, 48 and 72 hours (total of 5 ppm Cr6+ over 4 days). Statistically significant increases in DPXs (greater than 200% above controls) were observed in all Cr6+ treated size groups, as would be expected. However, there was no statistical difference between DPX levels of any of the size groups of fish (p>0.05, one-way ANOVA, with Bonferroni post-test). Although the significance of DPXs to fish health is not well understood, this assay may provide a useful, non-lethal tool to detect low level Cr6+ exposure of freshwater fish in their natural habitats.","DNA-Protein Crosslinks As A Potential Biomonitor Of Hexavalent Chromium Exposure In Rainbow Trout Abs: Hexavalent chromium (Cr6+) is found ubiquitously in many industrial waterways, as a result of mining, leather, steel, chrome plating and dye industries. Cr6+ has been demonstrated to cause DNA-protein crosslink (DPX) formation in developing sea urchin embryos, yet little is known about vertebrate aquatic wildlife. Fish erythrocytes are nucleated and represent a convenient tissue for studying DNA damage in vivo. Using an SDS/KCl precipitation technique, we attempted to determine if Cr6+ causes DPXs in erythrocytes of live trout at exposure levels which may be environmentally relevant. Fingerling trout (2-4?) were exposed to increasing [Cr6+] for 4 days at 15 degrees C. Dose dependent increases in DPXs were found at concentrations above 1 ppm, with 44, 116 (p<0.05), and 140% (p<0.01) above control levels at 1, 2 and 4 ppm, respectively. Next, fingerlings were exposed to 2 ppm Cr6+ in tank water for up to 21 days at 15 degrees C. Significant, time-dependent elevations in DPXs were observed in Cr6+ treated trout with 44, 92 and 201% increases above control DPX levels at 4, 7 and 21 days of exposure, respectively (p<0.05). Effect of body size on Cr6+-induced DPXs studied with four size groups of juvenile trout (2- 4?, 4-6?, 6-8? and 8-10?), housed together in a 55 gallon tank. Trout were exposed with an initial 2 ppm dose at time zero, and subsequent additions of 1 ppm at 24, 48 and 72 hours (total of 5 ppm Cr6+ over 4 days). Statistically significant increases in DPXs (greater than 200% above controls) were observed in all Cr6+ treated size groups, as would be expected. However, there was no statistical difference between DPX levels of any of the size groups of fish (p>0.05, one-way ANOVA, with Bonferroni post-test). Although the significance of DPXs to fish health is not well understood, this assay may provide a useful, non-lethal tool to detect low level Cr6+ exposure of freshwater fish in their natural habitats."
1510242,Sobol et al. 2006,Carcinogenic Cr(VI) and the nutritional supplement Cr(III) induce DNA deletions in yeast and mice,"The high levels of Cr(VI) contamination in drinking water across the country has led to concerns as to whether or not Cr(VI) ingestion from drinking water can lead to cancer. An argument against the role of Cr(VI) as an oral carcinogen is that it is reduced to Cr(III) in biological systems. Cr(III) is a popular nutritional supplement. In order to establish effective regulatory measures that protect the general public, the potential of Cr(VI) and Cr(III) to cause cancer via ingestion must be examined. There exists a large body of evidence, which confirms that chromosomal rearrangements such as DNA deletions are an important intermediate step in carcinogenesis. In this study, two systems screening for DNA deletions were used to compare the ability of Cr(VI) and Cr(III) to induce chromosomal rearrangements in the yeast S. cerevisiae and in vivo in the C57BL/6J pun/un mice. The mice were exposed to Cr(VI) and Cr(III) via drinking water during gestation and 70 kb DNA deletions at the pink-eyed unstable (pun) allele were determined in the resulting offspring.. Induction of DNA deletion in yeast was measured by growth on selective media. Both Cr(VI) and Cr(III) significantly induced DNA deletions in mice and yeast as compared to the spontaneous level of deletions. This result is particularly striking because the ability of either Cr(VI) or Cr(III) to cause DNA deletions, which are directly pertinent to cancer formation, has not been shown before in an in vivo system. Quantification of intracellular concentrations of Cr after exposure of yeast cells to either Cr(III) or Cr(VI) revealed that Cr(III) is more genotoxic than Cr(VI) once it is inside the cell. The quantification of tissue Cr concentration in mice confirms this trend. Therefore, this study concludes that both, the environmental contaminant Cr(VI) and the nutritional supplement Cr(III), when ingested via drinking water, lead to a genotoxic endpoint which is an intermediate in the process of carcinogenesis.","Carcinogenic Cr(VI) and the nutritional supplement Cr(III) induce DNA deletions in yeast and mice Abs: The high levels of Cr(VI) contamination in drinking water across the country has led to concerns as to whether or not Cr(VI) ingestion from drinking water can lead to cancer. An argument against the role of Cr(VI) as an oral carcinogen is that it is reduced to Cr(III) in biological systems. Cr(III) is a popular nutritional supplement. In order to establish effective regulatory measures that protect the general public, the potential of Cr(VI) and Cr(III) to cause cancer via ingestion must be examined. There exists a large body of evidence, which confirms that chromosomal rearrangements such as DNA deletions are an important intermediate step in carcinogenesis. In this study, two systems screening for DNA deletions were used to compare the ability of Cr(VI) and Cr(III) to induce chromosomal rearrangements in the yeast S. cerevisiae and in vivo in the C57BL/6J pun/un mice. The mice were exposed to Cr(VI) and Cr(III) via drinking water during gestation and 70 kb DNA deletions at the pink-eyed unstable (pun) allele were determined in the resulting offspring.. Induction of DNA deletion in yeast was measured by growth on selective media. Both Cr(VI) and Cr(III) significantly induced DNA deletions in mice and yeast as compared to the spontaneous level of deletions. This result is particularly striking because the ability of either Cr(VI) or Cr(III) to cause DNA deletions, which are directly pertinent to cancer formation, has not been shown before in an in vivo system. Quantification of intracellular concentrations of Cr after exposure of yeast cells to either Cr(III) or Cr(VI) revealed that Cr(III) is more genotoxic than Cr(VI) once it is inside the cell. The quantification of tissue Cr concentration in mice confirms this trend. Therefore, this study concludes that both, the environmental contaminant Cr(VI) and the nutritional supplement Cr(III), when ingested via drinking water, lead to a genotoxic endpoint which is an intermediate in the process of carcinogenesis."
1510235,Pereira et al. 1999,A study of embryotoxicity and teratogenesis of spurious lipsticks chemicals in the chick embryo,"In the present study three brands of spurious lipsticks produced in India by unknown company were tested for their teratogenic potential in chick embryos. Red coloured lipstick (R) contained erythrosine (FD and C Red No. 3), mercury (Hg 2+) - 1.256 ppm and lead (Pb 2+) - 0.845 ppm. Reddish brown lipstick (RB) contained erythrosine (FD and C Red No. 3), brilliant blue (FD and C Blue No.1), Hg 2+ - 0.182 ppm, Pb 2+ - 0.234 ppm and chromium (Cr 6+) - 0.068 ppm. Brown lipstick (B) contained fast green (FD and C Red No. 3), erythrosine (FD and C Red 3), Hg 2+ - 0.0255 ppm and Pb 2+ -0.266 ppm respectively in each lipstick. The lipsticks were dissolved in acetone and injected into developing eggs by inner shell membrane technique. Maximum number of deaths (within 5 days, of incubation) were observed for R and B lipsticks at a concentration of 25 ug level, but for RB lipstick maximum number of early deaths were observed at a concentration of 50 ug level. Thus indicating R and B lipstick are more embryotoxic than RB. The reason being, R and B lipsticks contained relatively higher concentration Hg 2+ and Pb 2+ in them. Malformed embryos were prevalently seen in all the three lipsticks and relatively few survivors were observed in B and RB lipsticks chemicals injected eggs. Most common malformations observed open coelom, edema of the lymphatics or lymph blebs, reduced number of digits, underdeveloped embryos, twisted legs, short hind limbs, stunted growth, regression of vitelline circulation, haemorrhage in the head and thorax, indicating that the multimetal constituents of lipsticks are capable of bringing about teratogenesis and embryotoxic in nature. Long term use of these lipsticks by Indian woman of lower economic background may lead to abnormal embryonic development.","A study of embryotoxicity and teratogenesis of spurious lipsticks chemicals in the chick embryo Abs: In the present study three brands of spurious lipsticks produced in India by unknown company were tested for their teratogenic potential in chick embryos. Red coloured lipstick (R) contained erythrosine (FD and C Red No. 3), mercury (Hg 2+) - 1.256 ppm and lead (Pb 2+) - 0.845 ppm. Reddish brown lipstick (RB) contained erythrosine (FD and C Red No. 3), brilliant blue (FD and C Blue No.1), Hg 2+ - 0.182 ppm, Pb 2+ - 0.234 ppm and chromium (Cr 6+) - 0.068 ppm. Brown lipstick (B) contained fast green (FD and C Red No. 3), erythrosine (FD and C Red 3), Hg 2+ - 0.0255 ppm and Pb 2+ -0.266 ppm respectively in each lipstick. The lipsticks were dissolved in acetone and injected into developing eggs by inner shell membrane technique. Maximum number of deaths (within 5 days, of incubation) were observed for R and B lipsticks at a concentration of 25 ug level, but for RB lipstick maximum number of early deaths were observed at a concentration of 50 ug level. Thus indicating R and B lipstick are more embryotoxic than RB. The reason being, R and B lipsticks contained relatively higher concentration Hg 2+ and Pb 2+ in them. Malformed embryos were prevalently seen in all the three lipsticks and relatively few survivors were observed in B and RB lipsticks chemicals injected eggs. Most common malformations observed open coelom, edema of the lymphatics or lymph blebs, reduced number of digits, underdeveloped embryos, twisted legs, short hind limbs, stunted growth, regression of vitelline circulation, haemorrhage in the head and thorax, indicating that the multimetal constituents of lipsticks are capable of bringing about teratogenesis and embryotoxic in nature. Long term use of these lipsticks by Indian woman of lower economic background may lead to abnormal embryonic development."
1510233,Beller et al. 2013,"Genomic and physiological characterization of the chromate-reducing, aquifer-derived Firmicute Pelosinus sp. strain HCF1","Pelosinus spp. are fermentative firmicutes that were recently reported to be prominent members of microbial communities at contaminated subsurface sites in multiple locations. Here we report metabolic characteristics and their putative genetic basis in Pelosinus sp. strain HCF1, an isolate that predominated anaerobic, Cr(VI)-reducing columns constructed with aquifer sediment. Strain HCF1 ferments lactate to propionate and acetate (the methylmalonyl-coenzyme A [CoA] pathway was identified in the genome), and its genome encodes two [NiFe]- and four [FeFe]-hydrogenases for H(2) cycling. The reduction of Cr(VI) and Fe(III) may be catalyzed by a flavoprotein with 42 to 51% sequence identity to both ChrR and FerB. This bacterium has unexpected capabilities and gene content associated with reduction of nitrogen oxides, including dissimilatory reduction of nitrate to ammonium (two copies of NrfH and NrfA were identified along with NarGHI) and a nitric oxide reductase (NorCB). In this strain, either H(2) or lactate can act as a sole electron donor for nitrate, Cr(VI), and Fe(III) reduction. Transcriptional studies demonstrated differential expression of hydrogenases and nitrate and nitrite reductases. Overall, the unexpected metabolic capabilities and gene content reported here broaden our perspective on what biogeochemical and ecological roles this species might play as a prominent member of microbial communities in subsurface environments.","Genomic and physiological characterization of the chromate-reducing, aquifer-derived Firmicute Pelosinus sp. strain HCF1 Abs: Pelosinus spp. are fermentative firmicutes that were recently reported to be prominent members of microbial communities at contaminated subsurface sites in multiple locations. Here we report metabolic characteristics and their putative genetic basis in Pelosinus sp. strain HCF1, an isolate that predominated anaerobic, Cr(VI)-reducing columns constructed with aquifer sediment. Strain HCF1 ferments lactate to propionate and acetate (the methylmalonyl-coenzyme A [CoA] pathway was identified in the genome), and its genome encodes two [NiFe]- and four [FeFe]-hydrogenases for H(2) cycling. The reduction of Cr(VI) and Fe(III) may be catalyzed by a flavoprotein with 42 to 51% sequence identity to both ChrR and FerB. This bacterium has unexpected capabilities and gene content associated with reduction of nitrogen oxides, including dissimilatory reduction of nitrate to ammonium (two copies of NrfH and NrfA were identified along with NarGHI) and a nitric oxide reductase (NorCB). In this strain, either H(2) or lactate can act as a sole electron donor for nitrate, Cr(VI), and Fe(III) reduction. Transcriptional studies demonstrated differential expression of hydrogenases and nitrate and nitrite reductases. Overall, the unexpected metabolic capabilities and gene content reported here broaden our perspective on what biogeochemical and ecological roles this species might play as a prominent member of microbial communities in subsurface environments."
1510231,Lison 1999,Importance of biotransformation pathways for interpreting biological monitoring of exposure,"BIOSIS COPYRIGHT: BIOL ABS. A detailed characterisation of the biotransformation pathways followed by the chemical of interest is, evidently, of primordial importance to design reliable biomonitoring programs. This short overview discusses some recent studies that are of potential interest for the development of new avenues of research. Four topics are addressed: tissue localisation of the metabolic process; importance of speciation; metabolic interactions and polymorphism and interindividual variability. While some of the","Importance of biotransformation pathways for interpreting biological monitoring of exposure Abs: BIOSIS COPYRIGHT: BIOL ABS. A detailed characterisation of the biotransformation pathways followed by the chemical of interest is, evidently, of primordial importance to design reliable biomonitoring programs. This short overview discusses some recent studies that are of potential interest for the development of new avenues of research. Four topics are addressed: tissue localisation of the metabolic process; importance of speciation; metabolic interactions and polymorphism and interindividual variability. While some of the"
1510229,Bennett et al. 2012,"In-Depth Survey Report: Experimental and Numerical Research on the Performance of Exposure Control Measures for Aircraft Painting Operations, Part II","See also PB2013-102754, Part 1. 2008, researchers from the Centers for Disease Control and Prevention/National Institute for Occupational Safety and Health (CDC/NIOSH) have been collaborating with Naval Facilities Engineering Service Center (NAVFAC ESC) engineers and Navy Medical Center San Diego (NMCSD) industrial hygienists to evaluate ventilation in a Navy aircraft painting hangar. The Navy seeks to keep worker exposures to air contaminants, including hexavalent chromium (CrVI), hexamethylene diisocyanate (HDI), methyl isobutyl ketone (MIBK), and others, at levels that meet regulatory health and safety standards, while limiting the environmental footprint, i.e. energy use, and operational costs of painting hangar ventilation. All project work, including the present study, refers to Naval Base Coronado, Building 465, Bay 6, in San Diego, California.","In-Depth Survey Report: Experimental and Numerical Research on the Performance of Exposure Control Measures for Aircraft Painting Operations, Part II Abs: See also PB2013-102754, Part 1. 2008, researchers from the Centers for Disease Control and Prevention/National Institute for Occupational Safety and Health (CDC/NIOSH) have been collaborating with Naval Facilities Engineering Service Center (NAVFAC ESC) engineers and Navy Medical Center San Diego (NMCSD) industrial hygienists to evaluate ventilation in a Navy aircraft painting hangar. The Navy seeks to keep worker exposures to air contaminants, including hexavalent chromium (CrVI), hexamethylene diisocyanate (HDI), methyl isobutyl ketone (MIBK), and others, at levels that meet regulatory health and safety standards, while limiting the environmental footprint, i.e. energy use, and operational costs of painting hangar ventilation. All project work, including the present study, refers to Naval Base Coronado, Building 465, Bay 6, in San Diego, California."
1510228,Bennett et al. 2011,"In-Depth Survey Report: Experimental and Numerical Research on the Performance of Exposure Control Measures for Aircraft Painting Operations, Part I","See also PB2013-102755, Part 2. Prepared in cooperation with Dept. of the Navy, Fleet Readiness and Center, Southwest, San Diego, CA. chers from the Centers for Disease Control and Prevention/National Institute for Occupational Safety and Health (CDC/NIOSH) investigated the performance of the ventilation system in a Navy aircraft paint finishing hangar, in terms of the efficiency and effectiveness of contaminant removal and worker exposure control. The Naval Facilities Engineering Service Center (NAVFAC ESC) and the Navy Medical Center San Diego (NMCSD), Industrial Hygienists collaborated with NIOSH in the study. The Navy seeks to keep worker exposures to air contaminants, including hexavalent chromium (CrVI), hexamethylene diisocyanate (HDI), methyl isobutyl ketone (MIBK), and others, below levels required by regulatory health and safety standards, while limiting the environmental footprint, i.e. energy use, and operational costs of paint finishing hangar ventilation. The specific operation under study was refinishing F/A-18C/D strike fighter aircraft in Bay 6 of Building 465, at Fleet Readiness Center Southwest, Naval Base Coronado, San Diego, California. Approximately twenty F-18s were processed per year in Bay 6, with each aircraft requiring 5 to 6 days.","In-Depth Survey Report: Experimental and Numerical Research on the Performance of Exposure Control Measures for Aircraft Painting Operations, Part I Abs: See also PB2013-102755, Part 2. Prepared in cooperation with Dept. of the Navy, Fleet Readiness and Center, Southwest, San Diego, CA. chers from the Centers for Disease Control and Prevention/National Institute for Occupational Safety and Health (CDC/NIOSH) investigated the performance of the ventilation system in a Navy aircraft paint finishing hangar, in terms of the efficiency and effectiveness of contaminant removal and worker exposure control. The Naval Facilities Engineering Service Center (NAVFAC ESC) and the Navy Medical Center San Diego (NMCSD), Industrial Hygienists collaborated with NIOSH in the study. The Navy seeks to keep worker exposures to air contaminants, including hexavalent chromium (CrVI), hexamethylene diisocyanate (HDI), methyl isobutyl ketone (MIBK), and others, below levels required by regulatory health and safety standards, while limiting the environmental footprint, i.e. energy use, and operational costs of paint finishing hangar ventilation. The specific operation under study was refinishing F/A-18C/D strike fighter aircraft in Bay 6 of Building 465, at Fleet Readiness Center Southwest, Naval Base Coronado, San Diego, California. Approximately twenty F-18s were processed per year in Bay 6, with each aircraft requiring 5 to 6 days."
1510226,Zaffiro et al. 2011,"Method 218.7: Determination of Hexavalent Chromium in Drinking Water by Ion Chromatography with Post-Column Derivatization and UV-Visible Spectroscopic Detection. Version 1,0",Method 218.7 provides procedures for the determination of hexavalent chromium Cr(VI) as the chromate anion CrO42- in finished drinking water using ion chromatography. Samples are analyzed by direct injection. This method is intended for use by analysts skilled in the operation of ion chromatographic instrumentation and in the interpretation of the associated data.,"Method 218.7: Determination of Hexavalent Chromium in Drinking Water by Ion Chromatography with Post-Column Derivatization and UV-Visible Spectroscopic Detection. Version 1,0 Abs: Method 218.7 provides procedures for the determination of hexavalent chromium Cr(VI) as the chromate anion CrO42- in finished drinking water using ion chromatography. Samples are analyzed by direct injection. This method is intended for use by analysts skilled in the operation of ion chromatographic instrumentation and in the interpretation of the associated data."
1510216,Wolf and  Wilson 2010,"Evaluation of Extraction Methods for Hexavalent Chromium Determination in Dusts, Ashes, and Soils","One of the difficulties in performing speciation analyses on solid samples is finding a suitable extraction method. Traditional methods for extraction of hexavalent chromium, Cr(VI), in soils, such as SW846 Method 3060A, can be tedious and are not always compatible with some determination methods. For example, the phosphate and high levels of carbonate and magnesium present in the U.S. Environmental Protection Agency (USEPA) Method 3060A digestion for Cr(VI) were found to be incompatible with the High Performance Liquid Chromatography-Inductively Coupled Plasma-Mass Spectrometry (HPLC-ICP-MS) detection method used by our laboratory. Modification of Method 3060A by eliminating the use of the phosphate buffer provided improved performance with the detection method, however dilutions are still necessary to achieve good chromatographic separation and detection of Cr(VI).","Evaluation of Extraction Methods for Hexavalent Chromium Determination in Dusts, Ashes, and Soils Abs: One of the difficulties in performing speciation analyses on solid samples is finding a suitable extraction method. Traditional methods for extraction of hexavalent chromium, Cr(VI), in soils, such as SW846 Method 3060A, can be tedious and are not always compatible with some determination methods. For example, the phosphate and high levels of carbonate and magnesium present in the U.S. Environmental Protection Agency (USEPA) Method 3060A digestion for Cr(VI) were found to be incompatible with the High Performance Liquid Chromatography-Inductively Coupled Plasma-Mass Spectrometry (HPLC-ICP-MS) detection method used by our laboratory. Modification of Method 3060A by eliminating the use of the phosphate buffer provided improved performance with the detection method, however dilutions are still necessary to achieve good chromatographic separation and detection of Cr(VI)."
1510213,Dougherty and  Jones 2008,Post-Katrina Air Quality Monitoring Report,"Final rept. red by Environmental Protection Agency, Research Triangle Park, NC. Emissions, Monitoring, and Analysis Div. S. Environmental Protection Agency evaluated the air quality in and around areas affected by Hurricane Katrina to characterize the magnitude and composition of potentially toxic air pollution. The post-Katrina Monitoring Network consisted of 30 monitoring stations that collected 24-hour air samples, typically on 1-, 3-, and/or 6-day schedules, for up to 12 months of monitoring. Five sites were designated as comprehensive sites and analyzed ambient air samples for concentrations of 60 volatile organic compounds (VOC) and 15 carbonyl compounds. Three of the comprehensive sites also analyzed for 80 speciated nonmethane organic compounds (SNMOC), 106 semivolatile compounds (SVOC), and hexavalent chromium. Four of the comprehensive sites analyzed 13 metal compounds. The remaining 25 non-comprehensive sites analyzed metal compounds only. Overall, nearly 155,000 ambient air concentrations were measured from October 2005 to September 2006. A complete description of the monitoring network, sampling schedule, test methods, and statistical analyses of the ambient air monitoring data are presented in the enclosed report. The final data are also included as appendices.","Post-Katrina Air Quality Monitoring Report Abs: Final rept. red by Environmental Protection Agency, Research Triangle Park, NC. Emissions, Monitoring, and Analysis Div. S. Environmental Protection Agency evaluated the air quality in and around areas affected by Hurricane Katrina to characterize the magnitude and composition of potentially toxic air pollution. The post-Katrina Monitoring Network consisted of 30 monitoring stations that collected 24-hour air samples, typically on 1-, 3-, and/or 6-day schedules, for up to 12 months of monitoring. Five sites were designated as comprehensive sites and analyzed ambient air samples for concentrations of 60 volatile organic compounds (VOC) and 15 carbonyl compounds. Three of the comprehensive sites also analyzed for 80 speciated nonmethane organic compounds (SNMOC), 106 semivolatile compounds (SVOC), and hexavalent chromium. Four of the comprehensive sites analyzed 13 metal compounds. The remaining 25 non-comprehensive sites analyzed metal compounds only. Overall, nearly 155,000 ambient air concentrations were measured from October 2005 to September 2006. A complete description of the monitoring network, sampling schedule, test methods, and statistical analyses of the ambient air monitoring data are presented in the enclosed report. The final data are also included as appendices."
1510209,Woldegiorgis et al. 2007,"Results from the Swedish National Screening Programme 2006. Subreport 5: Hexavalent Chromium, Cr(VI)","As an assignment from the Swedish Environmental Protection Agency, IVL has during 2006/2007 performed a 'Screening Study' of hexavalent chromium, Cr(VI). Also the concentrations of total chromium, Cr(tot) (i.e. Cr(III) + Cr(VI)) and lead, Pb(tot) were measured in the study.","Results from the Swedish National Screening Programme 2006. Subreport 5: Hexavalent Chromium, Cr(VI) Abs: As an assignment from the Swedish Environmental Protection Agency, IVL has during 2006/2007 performed a 'Screening Study' of hexavalent chromium, Cr(VI). Also the concentrations of total chromium, Cr(tot) (i.e. Cr(III) + Cr(VI)) and lead, Pb(tot) were measured in the study."
1510204,Pope and  Watt 2004,"Simulation of Ground-Water Flow in the Potomac-Raritan-Magothy Aquifer System, Pennsauken Township and Vicinity, New Jersey","Scientific investigations rept. ed in cooperation with Environmental Protection Agency, Washington, DC. tomac-Raritan-Magothy aquifer system is one of the primary sources of potable water in the Coastal Plain of New Jersey, particularly in heavily developed areas along the Delaware River. In Pennsauken Township, Camden County, local drinking-water supplies from this aquifer system have been contaminated by hexavalent chromium at concentrations that exceed the New Jersey maximum contaminant level. In particular, ground water at the Puchack well field has been adversely affected to the point where, since 1984, water is no longer withdrawn from this well field for public supply. The area that contains the Puchack well field was added to the National Priorities List in 1998 as a Superfund site. The U.S. Geological Survey (USGS) conducted a reconnaissance study from 1996 to 1998 during which hydrogeologic and water-quality data were collected and a ground-water-flow model was developed to describe the conditions in the aquifer system in the Pennsauken Township area. The current investigation by the USGS, in cooperation with the U.S. Environmental Protection Agency (USEPA), is an extension of the previous study. Results of the current study can be applied to a Remedial Investigation and Feasibility Study conducted at the Puchack well field Superfund site.","Simulation of Ground-Water Flow in the Potomac-Raritan-Magothy Aquifer System, Pennsauken Township and Vicinity, New Jersey Abs: Scientific investigations rept. ed in cooperation with Environmental Protection Agency, Washington, DC. tomac-Raritan-Magothy aquifer system is one of the primary sources of potable water in the Coastal Plain of New Jersey, particularly in heavily developed areas along the Delaware River. In Pennsauken Township, Camden County, local drinking-water supplies from this aquifer system have been contaminated by hexavalent chromium at concentrations that exceed the New Jersey maximum contaminant level. In particular, ground water at the Puchack well field has been adversely affected to the point where, since 1984, water is no longer withdrawn from this well field for public supply. The area that contains the Puchack well field was added to the National Priorities List in 1998 as a Superfund site. The U.S. Geological Survey (USGS) conducted a reconnaissance study from 1996 to 1998 during which hydrogeologic and water-quality data were collected and a ground-water-flow model was developed to describe the conditions in the aquifer system in the Pennsauken Township area. The current investigation by the USGS, in cooperation with the U.S. Environmental Protection Agency (USEPA), is an extension of the previous study. Results of the current study can be applied to a Remedial Investigation and Feasibility Study conducted at the Puchack well field Superfund site."
1510200,Paul et al. 2003,"Capstone Report on the Application, Monitoring, and Performance of Permeable Reactive Barriers for Ground-Water Remediation. Volume 2: Long-Term Monitoring of PRBs, Soils and Ground Water Sampling","This document is color dependent and/or landscape layout. It is currently available on CD-ROM and paper only. CD-ROM contains a 145 page document. See also PB2004-102949. eport discusses soil and ground-water sampling methods and procedures used to evaluate the long-term performance of permeable reactive barriers (PRBs) at two sites, Elizabeth City, NC, and the Denver Federal Center near Lakewood, CO. Both PRBs were installed in 1996 and have been monitored and studied since installation to determine their continued effectiveness for removing contaminants from ground water. An effective monitoring program requires appropriate soil and ground-water sampling techniques. For ground-water sampling, water quality indicator parameters must be monitored to determine when formation water has been accessed. Geochemical parameters include oxidation-reduction potential (ORP), pH, specific conductance, dissolved oxygen (DO), and turbidity. Field analytical methods are discussed along with interferences and issues which may arise when using certain electrodes or instruments in the field. Detailed field analytical procedures for hexavalent chromium, ferrous iron, alkalinity, hydrogen sulfide, and dissolved oxygen are described. Also included are laboratory methods for sample analyses for organics, cations, anions, and carbon. Sample collection methods, sample containers, preservation methods, and sample storage techniques are also discussed.","Capstone Report on the Application, Monitoring, and Performance of Permeable Reactive Barriers for Ground-Water Remediation. Volume 2: Long-Term Monitoring of PRBs, Soils and Ground Water Sampling Abs: This document is color dependent and/or landscape layout. It is currently available on CD-ROM and paper only. CD-ROM contains a 145 page document. See also PB2004-102949. eport discusses soil and ground-water sampling methods and procedures used to evaluate the long-term performance of permeable reactive barriers (PRBs) at two sites, Elizabeth City, NC, and the Denver Federal Center near Lakewood, CO. Both PRBs were installed in 1996 and have been monitored and studied since installation to determine their continued effectiveness for removing contaminants from ground water. An effective monitoring program requires appropriate soil and ground-water sampling techniques. For ground-water sampling, water quality indicator parameters must be monitored to determine when formation water has been accessed. Geochemical parameters include oxidation-reduction potential (ORP), pH, specific conductance, dissolved oxygen (DO), and turbidity. Field analytical methods are discussed along with interferences and issues which may arise when using certain electrodes or instruments in the field. Detailed field analytical procedures for hexavalent chromium, ferrous iron, alkalinity, hydrogen sulfide, and dissolved oxygen are described. Also included are laboratory methods for sample analyses for organics, cations, anions, and carbon. Sample collection methods, sample containers, preservation methods, and sample storage techniques are also discussed."
1510198,Mccleery et al. 2002,"Health Hazard Evaluation Report: HETA 97-0141-2819, Special Metals Corporation Princeton Powder Division, Princeton, Kentucky","The National Institute for Occupational Safety and Health (NIOSH) conducted a health hazard evaluation (HHE) at Special Metals Corporation, Princeton Powder Division, Princeton, Kentucky. NIOSH conducted this HHE at the request of employees at that facility who were concerned about the possible formation of hexavalent chromium (Cr(VI)) in the specialty alloy production operations, and of the potential health hazards from exposures to this and other materials associated with those operations. Health effects mentioned in the request included nose bleeds, sinusitis, gastric disturbance, and fatigue. In response to this request, NIOSH investigators conducted an initial environmental and medical investigation at the site on July 23 and 24, 1997. NIOSH investigators collected five personal breathing-zone (PBZ) and four area air samples for Cr(VI), seven PBZ and four area air samples for heavy metals, and six residual process bulk-material samples for Cr(VI). Two areas of the facility were also evaluated for noise levels. Based upon the initial findings, the NIOSH investigators determined that a follow-up visit was necessary to better characterize workers' exposures to several of the metals used at the facility, by conducting biological monitoring and additional environmental monitoring.","Health Hazard Evaluation Report: HETA 97-0141-2819, Special Metals Corporation Princeton Powder Division, Princeton, Kentucky Abs: The National Institute for Occupational Safety and Health (NIOSH) conducted a health hazard evaluation (HHE) at Special Metals Corporation, Princeton Powder Division, Princeton, Kentucky. NIOSH conducted this HHE at the request of employees at that facility who were concerned about the possible formation of hexavalent chromium (Cr(VI)) in the specialty alloy production operations, and of the potential health hazards from exposures to this and other materials associated with those operations. Health effects mentioned in the request included nose bleeds, sinusitis, gastric disturbance, and fatigue. In response to this request, NIOSH investigators conducted an initial environmental and medical investigation at the site on July 23 and 24, 1997. NIOSH investigators collected five personal breathing-zone (PBZ) and four area air samples for Cr(VI), seven PBZ and four area air samples for heavy metals, and six residual process bulk-material samples for Cr(VI). Two areas of the facility were also evaluated for noise levels. Based upon the initial findings, the NIOSH investigators determined that a follow-up visit was necessary to better characterize workers' exposures to several of the metals used at the facility, by conducting biological monitoring and additional environmental monitoring."
1510197,Walker 2001,"Effects of Pumping on Ground-Water Flow near Water-Supply Wells in the Lower Potomac-Raritan-Magothy Aquifer, Pennsauken Township, Camden County, New Jersey","Water resources investigation (Final). ed in cooperation with New Jersey Dept. of Environmental Protection, Trenton. the 1970's, hexavalent chromium has been detected in concentrations as great as 1.0 milligram per liter in wells at the Puckach well field operated by the Camden City Department of Utilities, Water Division (Water Department), forcing the Water Department to progressively remove five of its six wells from service between 1975 and 1988. The wells in the Puchack well field range in depth from 140 to 220 feet and are screened in the Lower Potomac-Raritan-Magothy aquifer. The Water Department has continued to pump Puchack Well 1 to maintain a hydraulic gradient toward the well field in an attempt to limit contaminant migration. In late 1997, concerns about treating the water withdrawn from Puchack Well 1 led water managers to consider temporarily discontinuing the pumping. In the spring of 1998, the U.S. Geological Survey (USGS), in cooperation with the New Jersey Department of Environmental Protection, began a preliminary assessment of the potential effects of temporarily removing Puchack Well 1 from service. Water levels in the Lower Potomac-Raritan-Magothy aquifer were measured during both pumping and non-pumping conditions to determine the direction and velocity of ground-water flow and the results were compared.","Effects of Pumping on Ground-Water Flow near Water-Supply Wells in the Lower Potomac-Raritan-Magothy Aquifer, Pennsauken Township, Camden County, New Jersey Abs: Water resources investigation (Final). ed in cooperation with New Jersey Dept. of Environmental Protection, Trenton. the 1970's, hexavalent chromium has been detected in concentrations as great as 1.0 milligram per liter in wells at the Puckach well field operated by the Camden City Department of Utilities, Water Division (Water Department), forcing the Water Department to progressively remove five of its six wells from service between 1975 and 1988. The wells in the Puchack well field range in depth from 140 to 220 feet and are screened in the Lower Potomac-Raritan-Magothy aquifer. The Water Department has continued to pump Puchack Well 1 to maintain a hydraulic gradient toward the well field in an attempt to limit contaminant migration. In late 1997, concerns about treating the water withdrawn from Puchack Well 1 led water managers to consider temporarily discontinuing the pumping. In the spring of 1998, the U.S. Geological Survey (USGS), in cooperation with the New Jersey Department of Environmental Protection, began a preliminary assessment of the potential effects of temporarily removing Puchack Well 1 from service. Water levels in the Lower Potomac-Raritan-Magothy aquifer were measured during both pumping and non-pumping conditions to determine the direction and velocity of ground-water flow and the results were compared."
1510195,Vaccarello 2001,Preliminary Hazard Classification for the In Situ Redox Manipulation Treatment for the 100-HR-3 Operable Unit (100-D Area)(Revision 2),"Prepared in cooperation with CH2M Hill, Greenwood Village, CO. Sponsored by Department of Energy, Washington, DC. u redox (reduction-oxidation) manipulation treatment for chromate contamination will be performed in the aquifer on the west side of the 100-D Area (100-HR-3 Operable Unit) of the Hanford Site. This in situ redox manipulation treatment involves the pumping of a solution, sodium dithionite, into ground wells to reduce the hexavalent chromium dissolved in groundwater to trivalent chromium, which will precipitate the chromium from the groundwater as immobile Cr(OH)(sub 3). This document serves as the preliminary hazard classification (PHC) for the 100-D Area In Situ Redox Manipulation Project. The PHC was prepared in accordance with the requirements for nuclear safety (DOE-RL 1996). Per these requirements, the PHC is based on the total hazardous substance inventories associated with the in situ redox treatability activities. Based on the estimated hazardous substance inventory contained within the evaporation pond, which will be used to evaporate the water extracted from the wells treated by the in situ redox method, the PHC for the facility was determined to be non-nuclear, low hazard.","Preliminary Hazard Classification for the In Situ Redox Manipulation Treatment for the 100-HR-3 Operable Unit (100-D Area)(Revision 2) Abs: Prepared in cooperation with CH2M Hill, Greenwood Village, CO. Sponsored by Department of Energy, Washington, DC. u redox (reduction-oxidation) manipulation treatment for chromate contamination will be performed in the aquifer on the west side of the 100-D Area (100-HR-3 Operable Unit) of the Hanford Site. This in situ redox manipulation treatment involves the pumping of a solution, sodium dithionite, into ground wells to reduce the hexavalent chromium dissolved in groundwater to trivalent chromium, which will precipitate the chromium from the groundwater as immobile Cr(OH)(sub 3). This document serves as the preliminary hazard classification (PHC) for the 100-D Area In Situ Redox Manipulation Project. The PHC was prepared in accordance with the requirements for nuclear safety (DOE-RL 1996). Per these requirements, the PHC is based on the total hazardous substance inventories associated with the in situ redox treatability activities. Based on the estimated hazardous substance inventory contained within the evaporation pond, which will be used to evaporate the water extracted from the wells treated by the in situ redox method, the PHC for the facility was determined to be non-nuclear, low hazard."
1510194,Blowes and  Ulrichmayer 1999,In-situ Permeable Reactive Barrier for the Treatment of Hexavalent Chromium and Trichloroethylene in Ground Water: Volume 3. Multicomponent Reactive Transport Modeling,"Available in paper copy and CD-ROM only. See also PB2000-105970, Volume 1, and PB2000-106693, Volume 2. Sponsored by National Risk Management Research Lab., Ada, OK. Subsurface Protection and Remediation Div. ve transport modeling has been conducted to describe the performance of the permeable reactive barrier at the Coast Guard Support Center near Elizabeth City, N.C. The reactive barrier was installed to treat groundwater contamination by hexavalent chromium and chlorinated organic solvents. The conceptual model of the Elizabeth City site described in previous reports provides the basis for the modelling study. The multicomponent reactive transport model MIN3P was used for the simulations. The essential reactions contained in the conceptual model are aqueous complexation reactions, combined reduction-corrosion reaction between the treatment material zero-valent iron and the contaminants or other electron acceptors dissolved in the ambient groundwater and the precipitation of secondary minerals within the reactive barrier. The simulations have been carried out along a cross-section through the barrier that corresponds to a transect of the monitoring network. One- and two-dimensional simulations were conducted. The one-dimensional simulations are carried out along a zone of preferential flow, which conveys the most pronounced Cr(VI)-contamination. The model has been calibrated using field data, laboratory data and reaction rates reported in the literature. The two-dimensional simulations were conducted based on hydraulic conductivities determined from slug-tests. These simulations allow an evaluation of the impact of preferential flow on the treatment of the contaminants and secondary reactions. The model results provide estimates of the potential effects of the consumption of zero-valent iron and the precipitation of secondary minerals on the long-term efficiency of the treatment system.","In-situ Permeable Reactive Barrier for the Treatment of Hexavalent Chromium and Trichloroethylene in Ground Water: Volume 3. Multicomponent Reactive Transport Modeling Abs: Available in paper copy and CD-ROM only. See also PB2000-105970, Volume 1, and PB2000-106693, Volume 2. Sponsored by National Risk Management Research Lab., Ada, OK. Subsurface Protection and Remediation Div. ve transport modeling has been conducted to describe the performance of the permeable reactive barrier at the Coast Guard Support Center near Elizabeth City, N.C. The reactive barrier was installed to treat groundwater contamination by hexavalent chromium and chlorinated organic solvents. The conceptual model of the Elizabeth City site described in previous reports provides the basis for the modelling study. The multicomponent reactive transport model MIN3P was used for the simulations. The essential reactions contained in the conceptual model are aqueous complexation reactions, combined reduction-corrosion reaction between the treatment material zero-valent iron and the contaminants or other electron acceptors dissolved in the ambient groundwater and the precipitation of secondary minerals within the reactive barrier. The simulations have been carried out along a cross-section through the barrier that corresponds to a transect of the monitoring network. One- and two-dimensional simulations were conducted. The one-dimensional simulations are carried out along a zone of preferential flow, which conveys the most pronounced Cr(VI)-contamination. The model has been calibrated using field data, laboratory data and reaction rates reported in the literature. The two-dimensional simulations were conducted based on hydraulic conductivities determined from slug-tests. These simulations allow an evaluation of the impact of preferential flow on the treatment of the contaminants and secondary reactions. The model results provide estimates of the potential effects of the consumption of zero-valent iron and the precipitation of secondary minerals on the long-term efficiency of the treatment system."
1510192,Bridges and  Patrick 2000,National Metal Finishing Environmental R and D Plan: An Update,"Sponsored by National Risk Management Research Lab., Cincinnati, OH. Office of Research and Development. ocument is an update to the National Metal Finishing Environmental R&amp;D Plan (EPA/600/R-97/095), dated September 1997. Based upon the finding of this update, it is recommended that Nickel be included as a high priority R&amp;D area. Technology Transfer and technical assistance resurfaced as an important item by representatives in the industry. Hexavalent Chromium, Cyanide, and Cadmium remained high priority R&amp;D areas, but the emphasis is shifting from emission control and other end of pipe approaches to research, development and demonstration of alternative materials and pollution prevention. Chlorinated Solvents require more emphasis on demonstration of alternative materials and information transfer. Technology Verification Protocol continues to be a high priority. Recycling and Metals Recovery should be focused more on finding technologies that will be appropriate for small platers. Emissions and Risk Characterization R&amp;D has progressed. Past R&amp;D in this area focused on the development of a metal finishing risk assessment tool that will target reduction of risks to workers. The R&amp;D need in this area is shifting to the development of a tool that not only will identify risks to workers and the environment but also will consider cost-effective pollution prevention solutions.","National Metal Finishing Environmental R and D Plan: An Update Abs: Sponsored by National Risk Management Research Lab., Cincinnati, OH. Office of Research and Development. ocument is an update to the National Metal Finishing Environmental R&amp;D Plan (EPA/600/R-97/095), dated September 1997. Based upon the finding of this update, it is recommended that Nickel be included as a high priority R&amp;D area. Technology Transfer and technical assistance resurfaced as an important item by representatives in the industry. Hexavalent Chromium, Cyanide, and Cadmium remained high priority R&amp;D areas, but the emphasis is shifting from emission control and other end of pipe approaches to research, development and demonstration of alternative materials and pollution prevention. Chlorinated Solvents require more emphasis on demonstration of alternative materials and information transfer. Technology Verification Protocol continues to be a high priority. Recycling and Metals Recovery should be focused more on finding technologies that will be appropriate for small platers. Emissions and Risk Characterization R&amp;D has progressed. Past R&amp;D in this area focused on the development of a metal finishing risk assessment tool that will target reduction of risks to workers. The R&amp;D need in this area is shifting to the development of a tool that not only will identify risks to workers and the environment but also will consider cost-effective pollution prevention solutions."
1510191,Blowes et al. 1999,In situ Permeable Reactive Barrier for the Treatment of Hexavalent Chromium and Trichloroethylene in Ground Water: Volume 1. Design and Installation,"Color illustrations reproduced in black and white. Sponsored by National Risk Management Research Lab., Ada, OK. Subsurface Protection and Remediation Div. long, 7.3 m deep, and 0.6 m wide permeable subsurface reactive wall was installed at the U.S. Coast Guard (USCG) Supports Center, near Elizabeth City, North Carolina, in June 1996. The reactive wall was designed to remediate hexavalent chromium (Cr(VI)) contaminated groundwater at the site, in addition to treating portions of a larger overlapping trichloroethylene (TCE) groundwater plume which has not yet been fully characterized. The wall was installed in approximately 6 hours using a continuous trenching technique, which simultaneously removed aquifer sediments and installed the porous reactive medium. The reactive medium was composed entirely on granular iron, with an average grain size (d(sub 50)) of 0.4mm. The reactive medium was selected from various mixtures on the basis of reaction rates with Cr(VI), TCE and degredation products, hydraulic conductivity, porosity, and cost.","In situ Permeable Reactive Barrier for the Treatment of Hexavalent Chromium and Trichloroethylene in Ground Water: Volume 1. Design and Installation Abs: Color illustrations reproduced in black and white. Sponsored by National Risk Management Research Lab., Ada, OK. Subsurface Protection and Remediation Div. long, 7.3 m deep, and 0.6 m wide permeable subsurface reactive wall was installed at the U.S. Coast Guard (USCG) Supports Center, near Elizabeth City, North Carolina, in June 1996. The reactive wall was designed to remediate hexavalent chromium (Cr(VI)) contaminated groundwater at the site, in addition to treating portions of a larger overlapping trichloroethylene (TCE) groundwater plume which has not yet been fully characterized. The wall was installed in approximately 6 hours using a continuous trenching technique, which simultaneously removed aquifer sediments and installed the porous reactive medium. The reactive medium was composed entirely on granular iron, with an average grain size (d(sub 50)) of 0.4mm. The reactive medium was selected from various mixtures on the basis of reaction rates with Cr(VI), TCE and degredation products, hydraulic conductivity, porosity, and cost."
1510190,Partymiller 1999,"Geotech, Inc. Cold Top Ex-situ Vitrification System: Innovative Technology Evaluation Report","Sponsored by National Risk Management Research Lab., Cincinnati, OH. Office of Research and Development. rfund Innovative Technology Evaluation (SITE) technology demonstration was conducted in February and March 1997 to evaluate the potential applicability and effectiveness of the Geotech Development Corporation Cold Top ex-situ vitrification technology on chromium-contaminated soils. One primary and five secondary objectives were identified for the SITE demonstration. The primary objective was to develop test data to evaluate whether waste and product streams from the Cold Top vitrification system pilot plant were capable of meeting the U.S. Environmental Protection Agency (EPA) Resource Conservation and Recovery Act (RCRA) definitions of a nonhazardous waste, based on the stream's leachable chromium content. Secondary objectives were to determine: (1) partitioning of chromium and hexavalent chromium from the contaminated soil into various waste and product streams; (2) the ability of the vitrified product to meet New Jersey Department of Environmental Protection (NJDEP) criteria for use as fill material (such as road construction aggregate); (3) the system's ability to meet applicable compliance regulations for air emissions of dioxins, furans, trace metals, particulates, and hydrogen chloride; (4) uncontrolled air emissions of the oxides of nitrogen, sulfur dioxide, carbon monoxide, and total hydrocarbons from the vitrification unit; and (5) projected operating costs of the technology per ton of soil.","Geotech, Inc. Cold Top Ex-situ Vitrification System: Innovative Technology Evaluation Report Abs: Sponsored by National Risk Management Research Lab., Cincinnati, OH. Office of Research and Development. rfund Innovative Technology Evaluation (SITE) technology demonstration was conducted in February and March 1997 to evaluate the potential applicability and effectiveness of the Geotech Development Corporation Cold Top ex-situ vitrification technology on chromium-contaminated soils. One primary and five secondary objectives were identified for the SITE demonstration. The primary objective was to develop test data to evaluate whether waste and product streams from the Cold Top vitrification system pilot plant were capable of meeting the U.S. Environmental Protection Agency (EPA) Resource Conservation and Recovery Act (RCRA) definitions of a nonhazardous waste, based on the stream's leachable chromium content. Secondary objectives were to determine: (1) partitioning of chromium and hexavalent chromium from the contaminated soil into various waste and product streams; (2) the ability of the vitrified product to meet New Jersey Department of Environmental Protection (NJDEP) criteria for use as fill material (such as road construction aggregate); (3) the system's ability to meet applicable compliance regulations for air emissions of dioxins, furans, trace metals, particulates, and hydrogen chloride; (4) uncontrolled air emissions of the oxides of nitrogen, sulfur dioxide, carbon monoxide, and total hydrocarbons from the vitrification unit; and (5) projected operating costs of the technology per ton of soil."
1510185,Blowes et al. 1997,In-situ Porous Reactive Wall for Treatment of Cr(VI) and Trichloroethylene in Groundwater,"Pub. in Proceedings of the 1997 International Containment Technology Conference and Exhibition, St. Petersburg, FL., February 9-12, 1997. Sponsored by National Risk Management Research Lab., Ada, OK. Subsurface Protection and Remediation Div. eable reactive wall for treating groundwater contaminated with hexavalent chromium (Cr(VI)) and trichloroethylene (TCE) was installed at the U.S. Coast Guard Support Center in Elizabeth City, NC in June, 1996. The porous reactive wall is 40m long, 0.6m wide, and 7m deep. The reactive wall was installed in less then six hours using a continuous trenching technique which simultaneously removed the aquifer material and replaced it with reactive materials. The wall is composed of 100% elemental iron in the form of iron filings. Preliminary laboratory experiments, with site groundwater and reactive materials similar to the full-scale wall components, were successful in decreasing 12 mg/L Cr(VI) and 1800 microg/L TCE to concentrations less than MCL levels. Detailed field monitoring will commence in August, 1996. The monitoring program will include groundwater sampling up-gradient, down-gradient and within the reactive wall, and collection of core samples for mineralogical and microbiological study.","In-situ Porous Reactive Wall for Treatment of Cr(VI) and Trichloroethylene in Groundwater Abs: Pub. in Proceedings of the 1997 International Containment Technology Conference and Exhibition, St. Petersburg, FL., February 9-12, 1997. Sponsored by National Risk Management Research Lab., Ada, OK. Subsurface Protection and Remediation Div. eable reactive wall for treating groundwater contaminated with hexavalent chromium (Cr(VI)) and trichloroethylene (TCE) was installed at the U.S. Coast Guard Support Center in Elizabeth City, NC in June, 1996. The porous reactive wall is 40m long, 0.6m wide, and 7m deep. The reactive wall was installed in less then six hours using a continuous trenching technique which simultaneously removed the aquifer material and replaced it with reactive materials. The wall is composed of 100% elemental iron in the form of iron filings. Preliminary laboratory experiments, with site groundwater and reactive materials similar to the full-scale wall components, were successful in decreasing 12 mg/L Cr(VI) and 1800 microg/L TCE to concentrations less than MCL levels. Detailed field monitoring will commence in August, 1996. The monitoring program will include groundwater sampling up-gradient, down-gradient and within the reactive wall, and collection of core samples for mineralogical and microbiological study."
1510183,Sabatini et al. 1997,"Innovative Measures for Subsurface Chromium Remediation: Source Zone, Concentrated Plume, and Dilute Plume","Environmental research brief. so PB97-192819 and PB97-122915. Sponsored by National Risk Management Research Lab., Ada, OK. Subsurface Protection and Remediation Div. nvironmental research brief reports on innovative measures for addressing subsurface chromium contamination. For the source zone, surfactant-enhanced chromium extraction is evaluated for expediting the removal of chromium from the source zone soils, thereby mitigating the continual feeding of the ground-water plume. For the concentrated plume, polyelectrolyte-enhanced ultrafiltration (PEUF) is evaluated as an innovative treatment process with desirable operating characteristics (less sludge production, higher quality final water, etc.), Relative to the dilute plume, the hydrogeological effectiveness of hydraulically passive, chemically reactive barrier systems is evaluated (i.e., in situ reduction of Cr(VI) to Cr(III)).","Innovative Measures for Subsurface Chromium Remediation: Source Zone, Concentrated Plume, and Dilute Plume Abs: Environmental research brief. so PB97-192819 and PB97-122915. Sponsored by National Risk Management Research Lab., Ada, OK. Subsurface Protection and Remediation Div. nvironmental research brief reports on innovative measures for addressing subsurface chromium contamination. For the source zone, surfactant-enhanced chromium extraction is evaluated for expediting the removal of chromium from the source zone soils, thereby mitigating the continual feeding of the ground-water plume. For the concentrated plume, polyelectrolyte-enhanced ultrafiltration (PEUF) is evaluated as an innovative treatment process with desirable operating characteristics (less sludge production, higher quality final water, etc.), Relative to the dilute plume, the hydrogeological effectiveness of hydraulically passive, chemically reactive barrier systems is evaluated (i.e., in situ reduction of Cr(VI) to Cr(III))."
1510182,Graham and  Monical 1997,"Contamination of Ground Water at the Tucson International Airport Area Superfund Site, Tucson, Arizona. Overview of Hydrogeologic Considerations, Conditions as of 1995, and Cleanup Efforts","Water resources investigations. red by Department of the Air Force, Washington, DC. rpose of this report is to provide a succinct, updated overview of the extent of ground-water contamination at the site and summarize technical information relevant to cleanup efforts. In this report, discussion is limited to a general summary and interpretation of the processes that allowed contaminants to enter the subsurface, to be transported to the underlying aquifer, and to spread in the aquifer to distant areas.","Contamination of Ground Water at the Tucson International Airport Area Superfund Site, Tucson, Arizona. Overview of Hydrogeologic Considerations, Conditions as of 1995, and Cleanup Efforts Abs: Water resources investigations. red by Department of the Air Force, Washington, DC. rpose of this report is to provide a succinct, updated overview of the extent of ground-water contamination at the site and summarize technical information relevant to cleanup efforts. In this report, discussion is limited to a general summary and interpretation of the processes that allowed contaminants to enter the subsurface, to be transported to the underlying aquifer, and to spread in the aquifer to distant areas."
1510181,Swell et al. 1997,"Chromium Biotreatment in Soil, Chapter 6","Book chapter. n the Encyclopedia of Environmental Analysis and Remediation. Prepared in cooperation with Dynamac Corp., Ada, OK. and Naval Research Lab., Washington, DC. tential for the biotreatment of CR(VI) wastes has received increased attention because the microbially mediated processes may offer cods, effective ness and sludge production. There are several biological mechanisms which may be suitable for metal treatments, including trnasofrmation, extracellular bindiing, complex formation, biosorption, and intracellular accumulation. Considering the more immobile and less toxic characteristics of Cr(III), the microbial reduction of Cr(VI) to Cr(III) appears to hold the most promise for the develoment of an innovative biotreatment technology. This reductive biotransofmration nont only leads to Cr(VI) detoxification but precipitates the metal in soils, therefore minimizing its potential risk to human helath and impacted ecosystem through decreases toxicity and exposure.","Chromium Biotreatment in Soil, Chapter 6 Abs: Book chapter. n the Encyclopedia of Environmental Analysis and Remediation. Prepared in cooperation with Dynamac Corp., Ada, OK. and Naval Research Lab., Washington, DC. tential for the biotreatment of CR(VI) wastes has received increased attention because the microbially mediated processes may offer cods, effective ness and sludge production. There are several biological mechanisms which may be suitable for metal treatments, including trnasofrmation, extracellular bindiing, complex formation, biosorption, and intracellular accumulation. Considering the more immobile and less toxic characteristics of Cr(III), the microbial reduction of Cr(VI) to Cr(III) appears to hold the most promise for the develoment of an innovative biotreatment technology. This reductive biotransofmration nont only leads to Cr(VI) detoxification but precipitates the metal in soils, therefore minimizing its potential risk to human helath and impacted ecosystem through decreases toxicity and exposure."
1510177,Puls et al. 1997,"Remediation of Chromate-Contaminated Ground Water Using an In-situ Permeable Reactive Mixture: Field Pilot Test, Elizabeth City, North Carolina","Presented at a meeting of the American Chemical Society, San Francisco, CA., April 13-17, 1997. See also PB96-169313, PB94-197597, and PB94-210457. t-scale field test was conducted near an old chrome plating facility on the U.S. Coast Guard (USCG) Support Center near Elizabeth City, North Carolina to evaluate the in-situ remediation of ground water contaminated by hexavalent chromium using permeable reactive barrier technology. The reactive media consisted of two types of zero-valent iron mixed with natural aquifer material and coarse sand. The remedial effectiveness of this innovative in situ technology was monitored over a twenty month period following emplacement in September 1994. In addition to monitoring the removal of contaminants from the aqueous phase, performance monitoring included attempts at mass balance circulations, changes in aqueous and solid phase goechemistry and changes in permeability.","Remediation of Chromate-Contaminated Ground Water Using an In-situ Permeable Reactive Mixture: Field Pilot Test, Elizabeth City, North Carolina Abs: Presented at a meeting of the American Chemical Society, San Francisco, CA., April 13-17, 1997. See also PB96-169313, PB94-197597, and PB94-210457. t-scale field test was conducted near an old chrome plating facility on the U.S. Coast Guard (USCG) Support Center near Elizabeth City, North Carolina to evaluate the in-situ remediation of ground water contaminated by hexavalent chromium using permeable reactive barrier technology. The reactive media consisted of two types of zero-valent iron mixed with natural aquifer material and coarse sand. The remedial effectiveness of this innovative in situ technology was monitored over a twenty month period following emplacement in September 1994. In addition to monitoring the removal of contaminants from the aqueous phase, performance monitoring included attempts at mass balance circulations, changes in aqueous and solid phase goechemistry and changes in permeability."
1510172,Puls et al. 1996,"Remediation of Chromate-Contaminated Groundwater Using Zero-Valent Iron: Field Test at USCG Support Center, Elizabeth City, North Carolina","Prepared in cooperation with ManTech Environmental Research Services Corp., Ada, OK. d test was conducted near an old hard-chrome plating facility on the USCG Support Center near Elizabeth City, North Carolina to evaluate the in situ remediation of ground water contaminated by hexavalent chromium using a passive permeable reactive barrier composed of a zero-valent iron-sand-aquifer material mixture. The remedial effectiveness of this innovative in situ technology was in situ technology was monitored over a one year period.","Remediation of Chromate-Contaminated Groundwater Using Zero-Valent Iron: Field Test at USCG Support Center, Elizabeth City, North Carolina Abs: Prepared in cooperation with ManTech Environmental Research Services Corp., Ada, OK. d test was conducted near an old hard-chrome plating facility on the USCG Support Center near Elizabeth City, North Carolina to evaluate the in situ remediation of ground water contaminated by hexavalent chromium using a passive permeable reactive barrier composed of a zero-valent iron-sand-aquifer material mixture. The remedial effectiveness of this innovative in situ technology was in situ technology was monitored over a one year period."
1510165,Echt et al. 1995,"Health Hazard Evaluation Report HETA 94-0417-2505, Tennant Company, Minneapolis, Minnesota","In response to a request from employees at the Golden Valley facility of the Tennant Company (SIC-3589), Minneapolis, Minnesota, a health hazard evaluation was conducted. Concern had been expressed over indoor environmental quality in offices and exposure to welding fumes. The company manufactured floor sweepers, scrubbers, and scarifiers. Headaches, sneezing, burning eyes, fatigue, depression, and mood swings were reported among office workers. Overall, 58% of those surveyed had one or more symptoms that occurred at work one or more days a week. Exposures to welding fume and most metals were below the applicable evaluation criteria. Eight hour time weighted average welding fume concentrations ranged from 0.33 to 1.6mg/m3. Titanium-dioxide (13463677) was present in greater than trace amounts in two of five samples; NIOSH has recommended that titanium-dioxide exposures be reduced to the lowest feasible concentration. Total chromium (7440473) exposure ranged from 0.003 to 0.01mg/m3, indicating that potential exposures to hexavalent chromium among frame welders should be evaluated. Manganese exposures ranged from 0.083 to 0.27mg/m3. The authors conclude that exposures to titanium-dioxide, chromium, and manganese were a cause for concern. Although no apparent cause for symptoms in office workers was found, ventilation system deficiencies were present. The authors recommend specific measures to reduce exposures and improve working conditions.","Health Hazard Evaluation Report HETA 94-0417-2505, Tennant Company, Minneapolis, Minnesota Abs: In response to a request from employees at the Golden Valley facility of the Tennant Company (SIC-3589), Minneapolis, Minnesota, a health hazard evaluation was conducted. Concern had been expressed over indoor environmental quality in offices and exposure to welding fumes. The company manufactured floor sweepers, scrubbers, and scarifiers. Headaches, sneezing, burning eyes, fatigue, depression, and mood swings were reported among office workers. Overall, 58% of those surveyed had one or more symptoms that occurred at work one or more days a week. Exposures to welding fume and most metals were below the applicable evaluation criteria. Eight hour time weighted average welding fume concentrations ranged from 0.33 to 1.6mg/m3. Titanium-dioxide (13463677) was present in greater than trace amounts in two of five samples; NIOSH has recommended that titanium-dioxide exposures be reduced to the lowest feasible concentration. Total chromium (7440473) exposure ranged from 0.003 to 0.01mg/m3, indicating that potential exposures to hexavalent chromium among frame welders should be evaluated. Manganese exposures ranged from 0.083 to 0.27mg/m3. The authors conclude that exposures to titanium-dioxide, chromium, and manganese were a cause for concern. Although no apparent cause for symptoms in office workers was found, ventilation system deficiencies were present. The authors recommend specific measures to reduce exposures and improve working conditions."
1510164,Palmer and  Puls 1994,Natural Attenuation of Hexavalent Chromium in Ground Water and Soils. Ground Water Issue,"Sponsored by Robert S. Kerr Environmental Research Lab., Ada, OK. per focuses on the natural attenuation of hexavalent chromium in soil and ground water. Much of the interest of natural attenuation of chromium stems from the great expense of remediating chromium-contaminated sites. Some of the issues discussed include the conditions that must be present for the necessary processes to occur, changes in toxicity, the time required for target concentrations to be reached, and assurances that chromium in the reduced state will remain immobile.","Natural Attenuation of Hexavalent Chromium in Ground Water and Soils. Ground Water Issue Abs: Sponsored by Robert S. Kerr Environmental Research Lab., Ada, OK. per focuses on the natural attenuation of hexavalent chromium in soil and ground water. Much of the interest of natural attenuation of chromium stems from the great expense of remediating chromium-contaminated sites. Some of the issues discussed include the conditions that must be present for the necessary processes to occur, changes in toxicity, the time required for target concentrations to be reached, and assurances that chromium in the reduced state will remain immobile."
1510160,Puls et al. 1994,Transport and Transformation of Hexavalent Chromium Through Soils and into Ground Water,"Journal article. n Jnl. of Soil Contamination, v3 n2 p203-224 Jun 94. Prepared in cooperation with ManTech Environmental Technology, Inc., Ada, OK. and Coast Guard, Elizabeth City, NC. iled characterization of the underlying and adjacent soils of a chromeplating shop was performed to provide information on the extent of soil and aquifer contamination at the site on the potential for off-site migration and environmental impact. Intact, moist cores were obtained from more than 40 different locations, resulting in more than 200 discrete samples for total metal analysis, selective extraction tests, and adsorption-reduction experiments, to assess the chemical speciation and distribution of chromium on the contaminated soils and its leaching potential. Surface analytical techniques were also used to determine chemical speciation and to further elucidate mineral fractions responsible for retention of the chromium on the soils and sediments. Adsorption and reduction capacities of the saturated aquifer sediments were variable and low, while the unsaturated soils' reduction capacities were much greater and were correlated with depth (decreasing capacity with increasing depth). The soils' adsorption and reduction capacities were eventually overwhelmed, however, and permitted the passage of Cr(VI) into the underlying ground water. (Copyright (c) 1994 AEHS).","Transport and Transformation of Hexavalent Chromium Through Soils and into Ground Water Abs: Journal article. n Jnl. of Soil Contamination, v3 n2 p203-224 Jun 94. Prepared in cooperation with ManTech Environmental Technology, Inc., Ada, OK. and Coast Guard, Elizabeth City, NC. iled characterization of the underlying and adjacent soils of a chromeplating shop was performed to provide information on the extent of soil and aquifer contamination at the site on the potential for off-site migration and environmental impact. Intact, moist cores were obtained from more than 40 different locations, resulting in more than 200 discrete samples for total metal analysis, selective extraction tests, and adsorption-reduction experiments, to assess the chemical speciation and distribution of chromium on the contaminated soils and its leaching potential. Surface analytical techniques were also used to determine chemical speciation and to further elucidate mineral fractions responsible for retention of the chromium on the soils and sediments. Adsorption and reduction capacities of the saturated aquifer sediments were variable and low, while the unsaturated soils' reduction capacities were much greater and were correlated with depth (decreasing capacity with increasing depth). The soils' adsorption and reduction capacities were eventually overwhelmed, however, and permitted the passage of Cr(VI) into the underlying ground water. (Copyright (c) 1994 AEHS)."
1510159,Munns et al. 1993,"Risk Assessment Pilot Study. Phase 3. Naval Construction Battalion Center, Davisville, Rhode Island","Final draft rept. ed in cooperation with Naval Command, Control and Ocean Surveillance Center, San Diego, CA. Sponsored by Environmental Research Lab., Narragansett, RI. ertake a marine ecological risk assessment at the Naval Construction Battalion Center (NCBC) Davisville, Rhode Island to determine the effect of hazardous waste disposal on Allen Harbor and Narragansett Bay. Allen Harbor, located in Narragansett Bay at NCBC Davisville, was closed to shellfishing by the Rhode Island Department of Environmental Management because of suspected hazardous waste contamination from a landfill and disposal area adjacent to the harbor. NCBC Davisville was added to the National Priority List in November 1989. Between 1946 and 1972, the 15-acre landfill received a wide variety of wastes, including sewage sludge, solvents, paints, chromic acid, PCB-contaminated waste oils, preservatives, blasting grit, and other municipal and industrial wastes generated at NCBC Davisville and at the Naval Air Station Quonset Point. Another site, also adjacent to Allen Harbor on Calf Pasture Point, was used for disposal of calcium hypochlorite decontaminating solution and chlorides.","Risk Assessment Pilot Study. Phase 3. Naval Construction Battalion Center, Davisville, Rhode Island Abs: Final draft rept. ed in cooperation with Naval Command, Control and Ocean Surveillance Center, San Diego, CA. Sponsored by Environmental Research Lab., Narragansett, RI. ertake a marine ecological risk assessment at the Naval Construction Battalion Center (NCBC) Davisville, Rhode Island to determine the effect of hazardous waste disposal on Allen Harbor and Narragansett Bay. Allen Harbor, located in Narragansett Bay at NCBC Davisville, was closed to shellfishing by the Rhode Island Department of Environmental Management because of suspected hazardous waste contamination from a landfill and disposal area adjacent to the harbor. NCBC Davisville was added to the National Priority List in November 1989. Between 1946 and 1972, the 15-acre landfill received a wide variety of wastes, including sewage sludge, solvents, paints, chromic acid, PCB-contaminated waste oils, preservatives, blasting grit, and other municipal and industrial wastes generated at NCBC Davisville and at the Naval Air Station Quonset Point. Another site, also adjacent to Allen Harbor on Calf Pasture Point, was used for disposal of calcium hypochlorite decontaminating solution and chlorides."
1510158,Mulrine 1993,Chromium Emissions from Industrial Process Cooling Towers: Background Information for Proposed Standards,"Final rept. al emission standards for hazardous air pollutants (NESHAP) are established under Section 112 of the Clean Air Act (CAA) (P.L. 101-459), as amended in 1990. Section 112(b) of the CAA contains a list of hazardous air pollutants (HAP's), which are the specific air toxics to be regulated by NESHAP. Chromium compounds are included on the list of HAP's established in Section 112(b) of the CAA. Section 112(c) requires the Administrator to use this pollutant list to develop and publish a list of source categories for which NESHAP are to be developed. Industrial process cooling towers (IPCT's), which emit chromium compounds, are included on the source category list. The background information document (BID) supports proposed standards for chromium emissions from IPCT's.","Chromium Emissions from Industrial Process Cooling Towers: Background Information for Proposed Standards Abs: Final rept. al emission standards for hazardous air pollutants (NESHAP) are established under Section 112 of the Clean Air Act (CAA) (P.L. 101-459), as amended in 1990. Section 112(b) of the CAA contains a list of hazardous air pollutants (HAP's), which are the specific air toxics to be regulated by NESHAP. Chromium compounds are included on the list of HAP's established in Section 112(b) of the CAA. Section 112(c) requires the Administrator to use this pollutant list to develop and publish a list of source categories for which NESHAP are to be developed. Industrial process cooling towers (IPCT's), which emit chromium compounds, are included on the source category list. The background information document (BID) supports proposed standards for chromium emissions from IPCT's."
1510150,Hall et al. 1992,Atmospheric Releases of Hexavalent Chromium from Hard Chromium Plating Operations,"Presented at American Electroplaters and Surface Finishers Society's Annual SUR/FIN Conference, Atlanta, GA., June 22-25, 1992, p767-776. Sponsored by Environmental Protection Agency, Cincinnati, OH. Risk Reduction Engineering Lab. udy represents an assessment of airborne fugitive hexavalent chromium concentrations at these facilities. In an effort to develop a model for stack emissions of Cr(VI), EPA data were reviewed and a correlation for chromium emissions was reported versus ampere-hours and plating bath volume. A modification of a stack sampling train was constructed to accommodate fugitive sampling efforts made at two hard chrome plating facilities. The levels found at both sites, for the most part, were below detection limits of 4 micrograms cu m and 6 micrograms cu m for the 1st and 2nd plant, respectively. The annual emission rates from Plants 1 and 2 are &amp;lt; 0.5 and &amp;lt; 1 lb Cr(VI) per year, respectively.","Atmospheric Releases of Hexavalent Chromium from Hard Chromium Plating Operations Abs: Presented at American Electroplaters and Surface Finishers Society's Annual SUR/FIN Conference, Atlanta, GA., June 22-25, 1992, p767-776. Sponsored by Environmental Protection Agency, Cincinnati, OH. Risk Reduction Engineering Lab. udy represents an assessment of airborne fugitive hexavalent chromium concentrations at these facilities. In an effort to develop a model for stack emissions of Cr(VI), EPA data were reviewed and a correlation for chromium emissions was reported versus ampere-hours and plating bath volume. A modification of a stack sampling train was constructed to accommodate fugitive sampling efforts made at two hard chrome plating facilities. The levels found at both sites, for the most part, were below detection limits of 4 micrograms cu m and 6 micrograms cu m for the 1st and 2nd plant, respectively. The annual emission rates from Plants 1 and 2 are &amp;lt; 0.5 and &amp;lt; 1 lb Cr(VI) per year, respectively."
1510149,Bostian et al. 1993,"Emissions from Sludge Incinerators with Venturi and Tray Scrubbers and Wet Electrostatic Precipitators: Metals, Chromium and Nickel Compounds, and Organics","See also PB91-151522 and PB92-151547. Prepared in cooperation with DEECO, Inc., Cary, NC., and Lewis (F. Michael), El Segundo, CA. rehensive test program was developed to determine the ratios of hexavalent to total chromium and nickel subsulfide to total nickel for a typical municipal wastewater sludge incinerator under normal combustion conditions and improved combustion conditions. Emissions of metals, hexavalent chromium, nickel subsulfide, polychlorinated dibenzodioxins and furans (PCDD/PCDFs), semi-volatile and volatile organic compounds, carbon monoxide (CO), and total hydrocarbons (THCs) from two multiple hearth incinerators and a fluidized bed incinerator were measured. The emissions were controlled at each unit with venturi scrubbers and, on two of the units, emissions from wet electrostatic precipitators (ESPs) were determined. Flue gas sampling was conducted at the inlet and outlet of the air pollution control devices at three separate sites. Gas concentrations, mass emission rates, metals-to-particulate ratios, and emissions factors were reported. Analytical results for the process samples were reported.","Emissions from Sludge Incinerators with Venturi and Tray Scrubbers and Wet Electrostatic Precipitators: Metals, Chromium and Nickel Compounds, and Organics Abs: See also PB91-151522 and PB92-151547. Prepared in cooperation with DEECO, Inc., Cary, NC., and Lewis (F. Michael), El Segundo, CA. rehensive test program was developed to determine the ratios of hexavalent to total chromium and nickel subsulfide to total nickel for a typical municipal wastewater sludge incinerator under normal combustion conditions and improved combustion conditions. Emissions of metals, hexavalent chromium, nickel subsulfide, polychlorinated dibenzodioxins and furans (PCDD/PCDFs), semi-volatile and volatile organic compounds, carbon monoxide (CO), and total hydrocarbons (THCs) from two multiple hearth incinerators and a fluidized bed incinerator were measured. The emissions were controlled at each unit with venturi scrubbers and, on two of the units, emissions from wet electrostatic precipitators (ESPs) were determined. Flue gas sampling was conducted at the inlet and outlet of the air pollution control devices at three separate sites. Gas concentrations, mass emission rates, metals-to-particulate ratios, and emissions factors were reported. Analytical results for the process samples were reported."
1510148,Mouradian et al. 1992,"Health Hazard Evaluation Report HETA 90-174-2231, Modern Materials Incorporated, Rochester, Indiana","In response to a request from the management of Modern Materials Incorporated (SIC-3479), Rochester, Indiana, possible chemical exposures associated with powder coating operations, specifically isocyanates used in some powder coatings, were evaluated. Air sampling indicated that the concentrations of most of the targeted chemicals were well below the Permissible Exposure Limits (PELs) and Recommended Exposure Limits (RELs). However, some exposures to epsilon-caprolactam (105602), formaldehyde (5000), and sulfur-dioxide (7446095) exceeded these limits. Conditions were observed which allowed dermal exposure to corrosives to occur, including hexavalent chromium (7440473). Inoperative eye washes, inadequate personal protective equipment, and apparent failure to meet communications requirements were also noted. The authors conclude that employees were exposed to potentially hazardous concentrations of aldehydes, epsilon-caprolactam, and sulfur-dioxide, and that there was a potential for hazardous exposures to other materials, and to unsafe conditions from inadequate use of safety devices and personal protective equipment. It was not possible to determine if workers had been exposed to unsafe levels of isocyanates or had developed isocyanate sensitization. The authors recommend specific measures to improve the conditions at this site.","Health Hazard Evaluation Report HETA 90-174-2231, Modern Materials Incorporated, Rochester, Indiana Abs: In response to a request from the management of Modern Materials Incorporated (SIC-3479), Rochester, Indiana, possible chemical exposures associated with powder coating operations, specifically isocyanates used in some powder coatings, were evaluated. Air sampling indicated that the concentrations of most of the targeted chemicals were well below the Permissible Exposure Limits (PELs) and Recommended Exposure Limits (RELs). However, some exposures to epsilon-caprolactam (105602), formaldehyde (5000), and sulfur-dioxide (7446095) exceeded these limits. Conditions were observed which allowed dermal exposure to corrosives to occur, including hexavalent chromium (7440473). Inoperative eye washes, inadequate personal protective equipment, and apparent failure to meet communications requirements were also noted. The authors conclude that employees were exposed to potentially hazardous concentrations of aldehydes, epsilon-caprolactam, and sulfur-dioxide, and that there was a potential for hazardous exposures to other materials, and to unsafe conditions from inadequate use of safety devices and personal protective equipment. It was not possible to determine if workers had been exposed to unsafe levels of isocyanates or had developed isocyanate sensitization. The authors recommend specific measures to improve the conditions at this site."
1510147,Tubbs et al. 1992,"Health Hazard Evaluation Report HETA 89-364-2202, ARMCO Advanced Materials Corporation, Butler, Pennsylvania","In response to a management request, an evaluation was made of possible hazardous working conditions at ARMCO Advanced Materials Corporation (SIC-3312), Butler, Pennsylvania. ARMCO produced primarily specialty steel products. An indirect method of electric heating was used at the facility to make steel. Concern was expressed about employee exposures to infrasound, electromagnetic radiation, and various dusts throughout the melt shop. The investigation was then expanded to include radiofrequency exposures at the Ultra-Rapid Annealing (URA) furnace located in the Strip Coating and Silicon Anneal Building (SCSAB). Air samples analyzed indicated that the recommended levels were being exceeded for chromium (7440473), manganese (7439965) and lead (7439921). Radiofrequency radiation measurements at the URA furnace and the visible radiation levels near the electric arc furnaces in the melt shops exceeded the appropriate evaluation criteria. The authors conclude that health hazards existed during the survey from excessive airborne levels of hexavalent chromium, manganese, and lead, high levels of optical radiation near the electric arc furnaces, and radiofrequency radiation at the URA furnace. The authors recommended measures to lower these exposures and suggested the institution of medical and environmental surveillance programs.","Health Hazard Evaluation Report HETA 89-364-2202, ARMCO Advanced Materials Corporation, Butler, Pennsylvania Abs: In response to a management request, an evaluation was made of possible hazardous working conditions at ARMCO Advanced Materials Corporation (SIC-3312), Butler, Pennsylvania. ARMCO produced primarily specialty steel products. An indirect method of electric heating was used at the facility to make steel. Concern was expressed about employee exposures to infrasound, electromagnetic radiation, and various dusts throughout the melt shop. The investigation was then expanded to include radiofrequency exposures at the Ultra-Rapid Annealing (URA) furnace located in the Strip Coating and Silicon Anneal Building (SCSAB). Air samples analyzed indicated that the recommended levels were being exceeded for chromium (7440473), manganese (7439965) and lead (7439921). Radiofrequency radiation measurements at the URA furnace and the visible radiation levels near the electric arc furnaces in the melt shops exceeded the appropriate evaluation criteria. The authors conclude that health hazards existed during the survey from excessive airborne levels of hexavalent chromium, manganese, and lead, high levels of optical radiation near the electric arc furnaces, and radiofrequency radiation at the URA furnace. The authors recommended measures to lower these exposures and suggested the institution of medical and environmental surveillance programs."
1510146,Dewees et al. 1992,"Emissions of Metals, Chromium and Nickel Species, and Organics from Municipal Wastewater Sludge Incinerators. Volume 8. Site 9 Emission Test Report","Final rept. 1989-91. so Volume 7, PB92-151612 and Volume 9, PB92-151638. Sponsored by Environmental Protection Agency, Cincinnati, OH. Risk Reduction Engineering Lab. is a secondary plant designed for 15 million gallons per day (MGD) of wastewater flow. The sludge incinerator at Site 9 is a seven (7) hearth, multiple hearth furnace (MHF) built by Nichols Engineering in 1974 controlled by an adjustable throat venturi, with a nominal pressure drop of 20 in. w.c.. After leaving the venturi, the gases pass upward through a three (3) plate tray scrubber with a Chevron mist eliminator. A 10 ft. x 10 ft., upflow, wet electrostatic precipitator, manufacturer by Beltran Associates, Inc., was installed during the first week of testing. The ratio of nickel subsulfide to total nickel in the emission at Site 9 is extremely low, with the sulfidic nickel species being measured at less than detection limit (about 1 to 2 percent of the total nickel). The ratio of hexavalent chromium to total chromium in the emissions at Site 9 was significantly higher that had been anticipated. Site 9 had only two semivolatile organic compounds detected under normal and improved combustion conditions benzyl alcohol and benzoic acid. Several additional compounds were found in the emissions for the normal or improved combustion conditions at Site 9; these compounds were 1,4-dichlorobenzene, 1,2-dichlorobenzene, 2-nitrophenol, 1,2,4-Trichlorobenzene, naphthalene, 2-methylnaphthalene, dibenzofuran, phenanthrene, bis(2-ethylhexyl)phthalate, phenol, 4-methylphenol, and 4-nitrophenol. The volatile organic compounds detected in the Site 9 multiple hearth incinerator emissions were similar to the compounds reported for Sites 1, 2, and 4 (other multiple hearth incinerator tested). Carbon tetrachloride and carbon tetrachloride, reported in the emissions at the other three sites, were not found in the emissions from Site 9.","Emissions of Metals, Chromium and Nickel Species, and Organics from Municipal Wastewater Sludge Incinerators. Volume 8. Site 9 Emission Test Report Abs: Final rept. 1989-91. so Volume 7, PB92-151612 and Volume 9, PB92-151638. Sponsored by Environmental Protection Agency, Cincinnati, OH. Risk Reduction Engineering Lab. is a secondary plant designed for 15 million gallons per day (MGD) of wastewater flow. The sludge incinerator at Site 9 is a seven (7) hearth, multiple hearth furnace (MHF) built by Nichols Engineering in 1974 controlled by an adjustable throat venturi, with a nominal pressure drop of 20 in. w.c.. After leaving the venturi, the gases pass upward through a three (3) plate tray scrubber with a Chevron mist eliminator. A 10 ft. x 10 ft., upflow, wet electrostatic precipitator, manufacturer by Beltran Associates, Inc., was installed during the first week of testing. The ratio of nickel subsulfide to total nickel in the emission at Site 9 is extremely low, with the sulfidic nickel species being measured at less than detection limit (about 1 to 2 percent of the total nickel). The ratio of hexavalent chromium to total chromium in the emissions at Site 9 was significantly higher that had been anticipated. Site 9 had only two semivolatile organic compounds detected under normal and improved combustion conditions benzyl alcohol and benzoic acid. Several additional compounds were found in the emissions for the normal or improved combustion conditions at Site 9; these compounds were 1,4-dichlorobenzene, 1,2-dichlorobenzene, 2-nitrophenol, 1,2,4-Trichlorobenzene, naphthalene, 2-methylnaphthalene, dibenzofuran, phenanthrene, bis(2-ethylhexyl)phthalate, phenol, 4-methylphenol, and 4-nitrophenol. The volatile organic compounds detected in the Site 9 multiple hearth incinerator emissions were similar to the compounds reported for Sites 1, 2, and 4 (other multiple hearth incinerator tested). Carbon tetrachloride and carbon tetrachloride, reported in the emissions at the other three sites, were not found in the emissions from Site 9."
1510145,Segall and  Dewees 1992,"Emissions of Metals, Chromium and Nickel Species, and Organics from Municipal Wastewater Sludge Incinerators. Volume 6. Site 8 Emission Test Report","Final rept. 1989-91. so Volume 5, PB92-151596 and Volume 7, PB92-151612. Prepared in cooperation with DEECO, Inc., Cary, NC., and Lewis (F. Michael), Mountain View, CA. Sponsored by Environmental Protection Agency, Cincinnati, OH. Risk Reduction Engineering Lab. te 8 facility is a 24.1 million gallons per day (MGD) secondary biological treatment plant with a 0.1 MGD septage handling facility. The wastewater influent comes from predominantly (90 percent) domestic sour ces. The treatment facility serves a population of approximately 175,000. All 22 tons per day of sludge solids are dewatered by two belt presses to a concentration of 22 to 25 percent solids. Approximately 15 to 17 tons of solids are dewatered by one press and fed to the fluidized bed incinerator. The air pollution control system associated with the incinerator consists of a water injection venturi, and an impingement tray scrubber. A pilot-scale wet eletrostatic precipitator had been installed and was tested. The ratio of hexavalent chromium to total chromium in the emissions was very low (despite relatively high total chromium levels), probably due to the short sludge retention time in the fluidized bed incinerator and the absence of alkaline material in the sludege. The ratio of nickel subsulfide to total nickel in the emissions was extremely low, with the nickel sulfide/subsulfide species measured at the inlet and midpoint being less than the detection limit. Compared to Site 3, a fluidized bed incinerator where the only semi-volatile organic compound detected was bis(2-ethylhexyl)phthalate, several additional semivolatiles were found in the emissions at Site 8. These were 1,2-dichlorobenzene, 1,4-dichlorobenzene, benzyl alcohol, benzoic acid, and naphthalene. The volatile organic compound emission results for Site 8 were consistent with the results for Site 3 (an other fluidized-bed incinerator). Carbon tetrachloride and chlorobenzene, reported in the emissions at Site 3, were not found in the emissions from Site 8.","Emissions of Metals, Chromium and Nickel Species, and Organics from Municipal Wastewater Sludge Incinerators. Volume 6. Site 8 Emission Test Report Abs: Final rept. 1989-91. so Volume 5, PB92-151596 and Volume 7, PB92-151612. Prepared in cooperation with DEECO, Inc., Cary, NC., and Lewis (F. Michael), Mountain View, CA. Sponsored by Environmental Protection Agency, Cincinnati, OH. Risk Reduction Engineering Lab. te 8 facility is a 24.1 million gallons per day (MGD) secondary biological treatment plant with a 0.1 MGD septage handling facility. The wastewater influent comes from predominantly (90 percent) domestic sour ces. The treatment facility serves a population of approximately 175,000. All 22 tons per day of sludge solids are dewatered by two belt presses to a concentration of 22 to 25 percent solids. Approximately 15 to 17 tons of solids are dewatered by one press and fed to the fluidized bed incinerator. The air pollution control system associated with the incinerator consists of a water injection venturi, and an impingement tray scrubber. A pilot-scale wet eletrostatic precipitator had been installed and was tested. The ratio of hexavalent chromium to total chromium in the emissions was very low (despite relatively high total chromium levels), probably due to the short sludge retention time in the fluidized bed incinerator and the absence of alkaline material in the sludege. The ratio of nickel subsulfide to total nickel in the emissions was extremely low, with the nickel sulfide/subsulfide species measured at the inlet and midpoint being less than the detection limit. Compared to Site 3, a fluidized bed incinerator where the only semi-volatile organic compound detected was bis(2-ethylhexyl)phthalate, several additional semivolatiles were found in the emissions at Site 8. These were 1,2-dichlorobenzene, 1,4-dichlorobenzene, benzyl alcohol, benzoic acid, and naphthalene. The volatile organic compound emission results for Site 8 were consistent with the results for Site 3 (an other fluidized-bed incinerator). Carbon tetrachloride and chlorobenzene, reported in the emissions at Site 3, were not found in the emissions from Site 8."
1510144,Segall and  Dewees 1992,"Emissions of Metals, Chromium and Nickel Species, and Organics from Municipal Wastewater Sludge Incinerators. Volume 4. Site 6 Emission Test Report - Appendices","Final rept. 1989-91. so Volume 3, PB92-151570 and Volume 5, PB92-151596. Prepared in cooperation with DEECO, Inc., Cary, NC., and Lewis (F. Michael), Mountain View, CA. Sponsored by Environmental Protection Agency, Cincinnati, OH. Risk Reduction Engineering Lab. , a multiple hearth furnace was tested under two operating conditions, normal combustion was compared with improved combustion conditions as indicated by reduced CO and THC emissions. The effect of lime conditioning on the conversion of total chromium in the sludge to hexavalent chromium emissions was also a primary concern at Site 6. Secondary objectives included comparing the results for chromium and nickel subspecies determined by different analytical procedures, gathering data on other metals and inorganic/organic gases in incinerator emissions, and assessing pollutant removal efficiencies by measuring emissions at both the inlet and outlet to the control system. Volume IV contains the appendices to volume III (Site 6 Emission Test Report). These are (1) Incinerator and Scrubber Operating Data; (2) Sampling and Analytical Methods; (3) Sample Calculations; (4) Analytical Data and Reports, and (5) Continuous Emissions Monitoring Data, Calibrations/One-min Average.","Emissions of Metals, Chromium and Nickel Species, and Organics from Municipal Wastewater Sludge Incinerators. Volume 4. Site 6 Emission Test Report - Appendices Abs: Final rept. 1989-91. so Volume 3, PB92-151570 and Volume 5, PB92-151596. Prepared in cooperation with DEECO, Inc., Cary, NC., and Lewis (F. Michael), Mountain View, CA. Sponsored by Environmental Protection Agency, Cincinnati, OH. Risk Reduction Engineering Lab. , a multiple hearth furnace was tested under two operating conditions, normal combustion was compared with improved combustion conditions as indicated by reduced CO and THC emissions. The effect of lime conditioning on the conversion of total chromium in the sludge to hexavalent chromium emissions was also a primary concern at Site 6. Secondary objectives included comparing the results for chromium and nickel subspecies determined by different analytical procedures, gathering data on other metals and inorganic/organic gases in incinerator emissions, and assessing pollutant removal efficiencies by measuring emissions at both the inlet and outlet to the control system. Volume IV contains the appendices to volume III (Site 6 Emission Test Report). These are (1) Incinerator and Scrubber Operating Data; (2) Sampling and Analytical Methods; (3) Sample Calculations; (4) Analytical Data and Reports, and (5) Continuous Emissions Monitoring Data, Calibrations/One-min Average."
1510143,Segall and  Dewees 1992,"Emissions of Metals, Chromium and Nickel Species, and Organics from Municipal Wastewater Sludge Incinerators. Volume 3. Site 6 Emissions Test Report","Final rept. 1989-91. so Volume 2, PB92-151562 and Volume 4, PB92-151588. Prepared in cooperation with DEECO, Inc., Cary, NC., and Lewis (F. Michael), Mountain View, CA. Sponsored by Environmental Protection Agency, Cincinnati, OH. Risk Reduction Engineering Lab. , a multiple hearth furnace was tested under two operating conditions, normal combustion was compared with improved combustion conditions as indicated by reduced CO and THC emissions. The effect of lime conditioning on the conversion of total chromium in the sludge to hexavalent chromium emissions was also a primary concern at Site 6. Secondary objectives included comparing the results for chromium and nickel subspecies determined by different analytical procedures, gathering data on other metals and inorganic/organic gases in incinerator emissions, and assessing pollutant removal efficiencies by measuring emissions at both the inlet and outlet to the control system. The Site 6 plant treats 30 million gallons a day of municipal and industrial wastewater. The blended primary/secondary sludge is dewatered to approximately 28% solids using recessed plate cloth filters. The metal mass emissions rate for the outlet runs averaged: As - not detected (&amp;lt; 508 mg/hr), Be - not detected (&amp;lt; 2.2 mg/hr), Cd - 1,450 mg/hr, Cr - 83.3 mg/hr, Pb - 21,100 mg/hr, and Ni - 73.9 mg/hr. The particulate mass emission rates averaged 42 kg/hr and 0.7 kg/hr, respectively for the inlet andoutlet. A positive correlation between the CO/CO2 ratios (an indication of combustion conditions) and the hexavalent to total chromium ratio was demonstrated for the outlet location. At low CO levels (good combustion) the ratio of hexavalent chromium to trivalent chromium was highest, with approximately 10% of the total chromium in the form of hexavalent chromium. It was anticipated that the nickel subsulfide emissions from multiple hearth incinerators would constitute less than 1% of the total nickel emissions. A wet chemical analysis indicated that within the detection limit (&amp;lt; 10%), no nickel subsulfide was present.","Emissions of Metals, Chromium and Nickel Species, and Organics from Municipal Wastewater Sludge Incinerators. Volume 3. Site 6 Emissions Test Report Abs: Final rept. 1989-91. so Volume 2, PB92-151562 and Volume 4, PB92-151588. Prepared in cooperation with DEECO, Inc., Cary, NC., and Lewis (F. Michael), Mountain View, CA. Sponsored by Environmental Protection Agency, Cincinnati, OH. Risk Reduction Engineering Lab. , a multiple hearth furnace was tested under two operating conditions, normal combustion was compared with improved combustion conditions as indicated by reduced CO and THC emissions. The effect of lime conditioning on the conversion of total chromium in the sludge to hexavalent chromium emissions was also a primary concern at Site 6. Secondary objectives included comparing the results for chromium and nickel subspecies determined by different analytical procedures, gathering data on other metals and inorganic/organic gases in incinerator emissions, and assessing pollutant removal efficiencies by measuring emissions at both the inlet and outlet to the control system. The Site 6 plant treats 30 million gallons a day of municipal and industrial wastewater. The blended primary/secondary sludge is dewatered to approximately 28% solids using recessed plate cloth filters. The metal mass emissions rate for the outlet runs averaged: As - not detected (&amp;lt; 508 mg/hr), Be - not detected (&amp;lt; 2.2 mg/hr), Cd - 1,450 mg/hr, Cr - 83.3 mg/hr, Pb - 21,100 mg/hr, and Ni - 73.9 mg/hr. The particulate mass emission rates averaged 42 kg/hr and 0.7 kg/hr, respectively for the inlet andoutlet. A positive correlation between the CO/CO2 ratios (an indication of combustion conditions) and the hexavalent to total chromium ratio was demonstrated for the outlet location. At low CO levels (good combustion) the ratio of hexavalent chromium to trivalent chromium was highest, with approximately 10% of the total chromium in the form of hexavalent chromium. It was anticipated that the nickel subsulfide emissions from multiple hearth incinerators would constitute less than 1% of the total nickel emissions. A wet chemical analysis indicated that within the detection limit (&amp;lt; 10%), no nickel subsulfide was present."
1510142,Dewees and  Segall 1992,"Emissions of Metals, Chromium and Nickel Species, and Organics from Municipal Wastewater Sludge Incinerators. Volume 2. Site 5 Emission Test Report Hexavalent Chromium Method Evaluation","Final rept. 1989-91. so Volume 1, PB92-151554 and Volume 3, PB92-151570. Prepared in cooperation with DEECO, Inc., Cary, NC., and Lewis (F. Michael), Mountain View, CA. Sponsored by Environmental Protection Agency, Cincinnati, OH. Risk Reduction Engineering Lab. e 5, three candidate sampling methods and two candidate analytical methods for hexavalent chromium were assessed. The conversion of hexavalent chromium (Cr (+6)) to other valence states of chromium during sampling and sample storage was of primary concern. Method 5-type samples and impinger train samples were collected by PEI Associates, Inc. Dilution train samples were collected bySouthern Research Institute. Method 5-type train samples were analyzed by Technology Applications, Inc.'s (TAI) staff under contract to EPA's Environmental Monitoring Systems Laboratory (EMSL) in Cincinnati, Ohio. Dilution train samples, Method 5-type samples, and impinger train samples were analyzed by Entropy Environmentalists, Inc. TAI used an ion chromatograph with post column reaction (IC/PCR) and inductively coupled argon plasmography/mass spectrometry (ICP/MS) to analyze the Method 5-type samples. A stable chromium isotope (63CR(+6)) spiked onto the Method 5 filter prior to sample collection was used to assess conversion of Cr(+6). The samples analyzed by Entropy were collected using a dilution train on an 8.5 in X 11 in glass fiber filter, a Method 5-type sampling train on an 82 mm quartz fiber filter, and an impinger sampling train with an alkaline impinger reagent, and spiked with native hexavalent chromium and a radioactively-labeled chromium isotope (51Cr(+6)). The samples were analyzed for hexavalent chromium by IC/PCR and for the radioactive isotopes by scintillation (gamma) counting. EMSL has not released the TAI data. The preliminary method evaluation testing demonstrated that all sampling methods had problems with conversion of hexavalent chromium.","Emissions of Metals, Chromium and Nickel Species, and Organics from Municipal Wastewater Sludge Incinerators. Volume 2. Site 5 Emission Test Report Hexavalent Chromium Method Evaluation Abs: Final rept. 1989-91. so Volume 1, PB92-151554 and Volume 3, PB92-151570. Prepared in cooperation with DEECO, Inc., Cary, NC., and Lewis (F. Michael), Mountain View, CA. Sponsored by Environmental Protection Agency, Cincinnati, OH. Risk Reduction Engineering Lab. e 5, three candidate sampling methods and two candidate analytical methods for hexavalent chromium were assessed. The conversion of hexavalent chromium (Cr (+6)) to other valence states of chromium during sampling and sample storage was of primary concern. Method 5-type samples and impinger train samples were collected by PEI Associates, Inc. Dilution train samples were collected bySouthern Research Institute. Method 5-type train samples were analyzed by Technology Applications, Inc.'s (TAI) staff under contract to EPA's Environmental Monitoring Systems Laboratory (EMSL) in Cincinnati, Ohio. Dilution train samples, Method 5-type samples, and impinger train samples were analyzed by Entropy Environmentalists, Inc. TAI used an ion chromatograph with post column reaction (IC/PCR) and inductively coupled argon plasmography/mass spectrometry (ICP/MS) to analyze the Method 5-type samples. A stable chromium isotope (63CR(+6)) spiked onto the Method 5 filter prior to sample collection was used to assess conversion of Cr(+6). The samples analyzed by Entropy were collected using a dilution train on an 8.5 in X 11 in glass fiber filter, a Method 5-type sampling train on an 82 mm quartz fiber filter, and an impinger sampling train with an alkaline impinger reagent, and spiked with native hexavalent chromium and a radioactively-labeled chromium isotope (51Cr(+6)). The samples were analyzed for hexavalent chromium by IC/PCR and for the radioactive isotopes by scintillation (gamma) counting. EMSL has not released the TAI data. The preliminary method evaluation testing demonstrated that all sampling methods had problems with conversion of hexavalent chromium."
1510141,Segall et al. 1992,"Emissions of Metals, Chromium and Nickel Species, and Organics from Municipal Wastewater Sludge Incinerators. Volume 1. Summary Report","Final rept. 1989-91. so Volume 2, PB92-151562. Prepared in cooperation with DEECO, Inc., Cary, NC., and Lewis (F. Michael), Mountain View, CA. Sponsored by Environmental Protection Agency, Cincinnati, OH. Risk Reduction Engineering Lab. e 5 (continuing a numbering system initiated in a previous 4-site project) tests were only conducted for methods development purposes. At Site 6, emissions were measured at the inlet and outlet of the control device. At Site 7, an evaluation of CO and THC CEMSs was performed. At Sites 8 and 9, emissions were measured at the inlet of the venturi scrubber, at the midpoint located between the venturi scrubber and the wet ESP, and at the outlet of the wet ESP. For Sites 6, 8, and 9, midpoint and outlet air emission samples were collected and analyzed for particulate matter, metals, PCDD/PCDFs, volatile and semivolatile compounds (except Site 6), and hexavalent chromium and nickel subsulfide species. Continuous emission monitoring (CEM) for O2, CO2, CO, SO2, and NOx at the control system inlet and O2 (except Site 6), CO2 (except Sites 6 and 9), CO, SO2 (except Sites 6 and 9), NOx (except Sites 6 and 9), and THC was conducted at the control system outlet stack. The metals found in the greatest concentration in the sludge were lead, chromium and nickel. The need for sampling of hexavalent chromium without artifact formation and analysis of the resulting samples specifically for hexavalent chromium at low concentrations was a major accomplishment of the test program. The results of the nickel sampling and analysis indicate that within the detection limit of the wet chemical method, no nickel subsulfide was present in the air emissions. At Site 6 and Site 9, a positive correlation between carbon monoxide emissions and total hydrocarbon (THC) emissions was observed. At Site 7, a positive correlation was demonstrated between the 'Hot' and 'Cold' THC CEMs.","Emissions of Metals, Chromium and Nickel Species, and Organics from Municipal Wastewater Sludge Incinerators. Volume 1. Summary Report Abs: Final rept. 1989-91. so Volume 2, PB92-151562. Prepared in cooperation with DEECO, Inc., Cary, NC., and Lewis (F. Michael), Mountain View, CA. Sponsored by Environmental Protection Agency, Cincinnati, OH. Risk Reduction Engineering Lab. e 5 (continuing a numbering system initiated in a previous 4-site project) tests were only conducted for methods development purposes. At Site 6, emissions were measured at the inlet and outlet of the control device. At Site 7, an evaluation of CO and THC CEMSs was performed. At Sites 8 and 9, emissions were measured at the inlet of the venturi scrubber, at the midpoint located between the venturi scrubber and the wet ESP, and at the outlet of the wet ESP. For Sites 6, 8, and 9, midpoint and outlet air emission samples were collected and analyzed for particulate matter, metals, PCDD/PCDFs, volatile and semivolatile compounds (except Site 6), and hexavalent chromium and nickel subsulfide species. Continuous emission monitoring (CEM) for O2, CO2, CO, SO2, and NOx at the control system inlet and O2 (except Site 6), CO2 (except Sites 6 and 9), CO, SO2 (except Sites 6 and 9), NOx (except Sites 6 and 9), and THC was conducted at the control system outlet stack. The metals found in the greatest concentration in the sludge were lead, chromium and nickel. The need for sampling of hexavalent chromium without artifact formation and analysis of the resulting samples specifically for hexavalent chromium at low concentrations was a major accomplishment of the test program. The results of the nickel sampling and analysis indicate that within the detection limit of the wet chemical method, no nickel subsulfide was present in the air emissions. At Site 6 and Site 9, a positive correlation between carbon monoxide emissions and total hydrocarbon (THC) emissions was observed. At Site 7, a positive correlation was demonstrated between the 'Hot' and 'Cold' THC CEMs."
1510140,Barcelona and  Holm 1991,Oxidation-Reduction Capacities of Aquifer Solids,"Journal article. n Environmental Science Technology, v25 n9 p1565-1572 1991. Prepared in cooperation with Illinois State Water Survey Div., Champaign. Sponsored by Robert S. Kerr Environmental Research Lab., Ada, OK. ion-reduction processes play a major role in the mobility, transport, and fate of inorganic and organic chemical constituents in natural waters. Therefore, the manipulation of redox conditions in natural and treated water systems is assumed to be a common option for the control of contaminant concentrations. Measurements of the oxidation (i.e., of aqueous Cr(2+)) and reduction (i.e., of aqueous Cr2O7(2-) and H2O2) capacities of aquifer solids and groundwater have been made on samples from a sand-and-gravel aquifer. The groundwater contributed less than 1% of the system oxidation or reduction poising capacity. Reduction capacities averaged 0.095, 0.111, and 0.136 mequiv/g of dry solids for oxic, transitional, and reducing Eh conditions, respectively. Measured oxidation capacities averaged 0.4 mequiv/g of dry solids over the range of redox intensity conditions. These capacities represent considerable resistance to the adjustment of redox conditions even at uncontaminated sites. Hydrogen peroxide reduction by aquifer solid samples proceeds rapidly relative to microbially mediated decomposition. The study indicates the need for closer scrutiny of the predictability and cost effectiveness of attempts to manipulate redox conditions in poorly poised aquifer systems.","Oxidation-Reduction Capacities of Aquifer Solids Abs: Journal article. n Environmental Science Technology, v25 n9 p1565-1572 1991. Prepared in cooperation with Illinois State Water Survey Div., Champaign. Sponsored by Robert S. Kerr Environmental Research Lab., Ada, OK. ion-reduction processes play a major role in the mobility, transport, and fate of inorganic and organic chemical constituents in natural waters. Therefore, the manipulation of redox conditions in natural and treated water systems is assumed to be a common option for the control of contaminant concentrations. Measurements of the oxidation (i.e., of aqueous Cr(2+)) and reduction (i.e., of aqueous Cr2O7(2-) and H2O2) capacities of aquifer solids and groundwater have been made on samples from a sand-and-gravel aquifer. The groundwater contributed less than 1% of the system oxidation or reduction poising capacity. Reduction capacities averaged 0.095, 0.111, and 0.136 mequiv/g of dry solids for oxic, transitional, and reducing Eh conditions, respectively. Measured oxidation capacities averaged 0.4 mequiv/g of dry solids over the range of redox intensity conditions. These capacities represent considerable resistance to the adjustment of redox conditions even at uncontaminated sites. Hydrogen peroxide reduction by aquifer solid samples proceeds rapidly relative to microbially mediated decomposition. The study indicates the need for closer scrutiny of the predictability and cost effectiveness of attempts to manipulate redox conditions in poorly poised aquifer systems."
1510139,Carver 1991,Laboratory and Field Evaluations of a Methodology for Determining Hexavalent Chromium Emissions from Stationary Sources,"Final rept. red by Environmental Protection Agency, Research Triangle Park, NC. Atmospheric Research and Exposure Assessment Lab. udy was initiated to determine whether chromium emissions should be regulated under Section 112 of the Clean Air Act National Emissions Standards for Hazardous Air Pollutants (NESHAP). To support stationary source regulations, it is important that (1) the sampling procedure not change the chromium valence state during sampling and (2) an analytical technique for measuring low concentration levels of chromium be available. These goals are achieved with the current EPA 'Draft Method for Sampling and Analysis of Hexavalent Chromium at Stationary Sources.' The draft method utilizes a recirculating system to flush impinger reagent into the sampling nozzle during sample collection. Immediate contact of the stack gas with impinger reagent 'fixes' the chromium valence state. Ion chromatography coupled with post column derivatization and ultraviolet visible detector is used to analyze Cr(VI) in the parts per trillion range. Field tests were conducted at metal plating facilities, industrial cooling towers, municipal waste incinerators, sewage sludge incinerators, and hazardous waste incinerators. It was at the hazardous waste facility that the new method was proven to have acceptable precision and essentially no conversion in the sample train.","Laboratory and Field Evaluations of a Methodology for Determining Hexavalent Chromium Emissions from Stationary Sources Abs: Final rept. red by Environmental Protection Agency, Research Triangle Park, NC. Atmospheric Research and Exposure Assessment Lab. udy was initiated to determine whether chromium emissions should be regulated under Section 112 of the Clean Air Act National Emissions Standards for Hazardous Air Pollutants (NESHAP). To support stationary source regulations, it is important that (1) the sampling procedure not change the chromium valence state during sampling and (2) an analytical technique for measuring low concentration levels of chromium be available. These goals are achieved with the current EPA 'Draft Method for Sampling and Analysis of Hexavalent Chromium at Stationary Sources.' The draft method utilizes a recirculating system to flush impinger reagent into the sampling nozzle during sample collection. Immediate contact of the stack gas with impinger reagent 'fixes' the chromium valence state. Ion chromatography coupled with post column derivatization and ultraviolet visible detector is used to analyze Cr(VI) in the parts per trillion range. Field tests were conducted at metal plating facilities, industrial cooling towers, municipal waste incinerators, sewage sludge incinerators, and hazardous waste incinerators. It was at the hazardous waste facility that the new method was proven to have acceptable precision and essentially no conversion in the sample train."
1510138,Dewees et al. 1991,"Sampling and Analysis of Municipal Wastewater Sludge Incinerator Emissions for Metals, Metal Species, and Organics","Presented at the Annual Meeting of the Air and Waste Management Association (83rd), Pittsburgh, PA., June 24-29, 1990. Sponsored by Environmental Protection Agency, Cincinnati, OH. Risk Reduction Engineering Lab. is concern regarding chromium and nickel species in the emissions from incineration of municipal wastewater sludge because of the associated cancer risk. The Environmental Protection Agency's (EPA) Office of Water Regulations and Standards (OWRS) is developing new regulations for sewage sludge incinerators and EPA's Risk Reduction Engineering Laboratory (RREL) has been assisting OWRS in the collection of supporting data. The paper reports new data on emissions of chromium and nickel species and associated emissions needed to respond to public comments. The primary objectives of the portion of the RREL/OWRS research program described in the paper are to determine (1) the ratio of hexavalent chromium to total chromium and (2) the ratio of nickel subsulfide to total nickel in sewage sludge incinerator emissions under several incinerator operating conditions. Secondary objectives include comparing the analytical results for emissions of chromium and nickel subspecies determined by different analytical procedures, and gathering data on other metals and inorganic and organic gaseous components in uncontrolled and controlled incinerator emissions.","Sampling and Analysis of Municipal Wastewater Sludge Incinerator Emissions for Metals, Metal Species, and Organics Abs: Presented at the Annual Meeting of the Air and Waste Management Association (83rd), Pittsburgh, PA., June 24-29, 1990. Sponsored by Environmental Protection Agency, Cincinnati, OH. Risk Reduction Engineering Lab. is concern regarding chromium and nickel species in the emissions from incineration of municipal wastewater sludge because of the associated cancer risk. The Environmental Protection Agency's (EPA) Office of Water Regulations and Standards (OWRS) is developing new regulations for sewage sludge incinerators and EPA's Risk Reduction Engineering Laboratory (RREL) has been assisting OWRS in the collection of supporting data. The paper reports new data on emissions of chromium and nickel species and associated emissions needed to respond to public comments. The primary objectives of the portion of the RREL/OWRS research program described in the paper are to determine (1) the ratio of hexavalent chromium to total chromium and (2) the ratio of nickel subsulfide to total nickel in sewage sludge incinerator emissions under several incinerator operating conditions. Secondary objectives include comparing the analytical results for emissions of chromium and nickel subspecies determined by different analytical procedures, and gathering data on other metals and inorganic and organic gaseous components in uncontrolled and controlled incinerator emissions."
1510136,Salisbury et al. 1991,"Hazard Evaluation and Technical Assistance Report HETA 89-276-L2093, Lockheed Aeronautical Systems Company, Marietta, Georgia","In response to a request from the International Association of Machinists and Aerospace Workers, NIOSH conducted an evaluation at the Lockheed Aeronautical Systems Company, Marietta, Georgia due to concerns about health hazards from exposure to epoxy and polyurethane paints being sprayed in open areas on the C-130 aircraft assembly line. About 350 employees worked on the final assembly line. Air samples were collected to evaluate potential exposures to diisocyanates, organic vapors, and trace metals released during painting operations. Environmental sampling demonstrated minimal risk of exposure for nonpainters to organic vapors, isocyanate prepolymers, and toxic metals released into the open atmosphere during first shift painting of wing panels. Area monitors showed airborne concentrations of organic vapors and hazardous particulates which were below current occupational limits. Exposure risks to hexavalent chromium (7440473) compounds were shown for one of the painters spraying primer containing strontium-chromate (7789062). The large interior volume of the building and the rapid dispersion and upward drift of paint overspray may tend to reduce the chance of floor level exposures. The practice of spraying polyurethane when the building was mostly unoccupied should prevent new cases of respiratory sensitization to diisocyanates among the C-130 production workers. The authors recommend specific measures to reduce exposures to diisocyanates and hexavalent chromium compounds.","Hazard Evaluation and Technical Assistance Report HETA 89-276-L2093, Lockheed Aeronautical Systems Company, Marietta, Georgia Abs: In response to a request from the International Association of Machinists and Aerospace Workers, NIOSH conducted an evaluation at the Lockheed Aeronautical Systems Company, Marietta, Georgia due to concerns about health hazards from exposure to epoxy and polyurethane paints being sprayed in open areas on the C-130 aircraft assembly line. About 350 employees worked on the final assembly line. Air samples were collected to evaluate potential exposures to diisocyanates, organic vapors, and trace metals released during painting operations. Environmental sampling demonstrated minimal risk of exposure for nonpainters to organic vapors, isocyanate prepolymers, and toxic metals released into the open atmosphere during first shift painting of wing panels. Area monitors showed airborne concentrations of organic vapors and hazardous particulates which were below current occupational limits. Exposure risks to hexavalent chromium (7440473) compounds were shown for one of the painters spraying primer containing strontium-chromate (7789062). The large interior volume of the building and the rapid dispersion and upward drift of paint overspray may tend to reduce the chance of floor level exposures. The practice of spraying polyurethane when the building was mostly unoccupied should prevent new cases of respiratory sensitization to diisocyanates among the C-130 production workers. The authors recommend specific measures to reduce exposures to diisocyanates and hexavalent chromium compounds."
1510135,Newman and  Klein 1990,"Health Hazard Evaluation Report HETA 88-068-2077, Schmidt Cabinet Company, New Salisbury, Indiana","In response to a request from the Schmidt Cabinet Company (SIC-2434), New Salisbury, Indiana, an investigation was undertaken of the exhaust ventilation system and finishing room exposures. The firm manufactured kitchen cabinets and bathroom vanities. Approximately 90 workers were employed at the facility. The cabinets were made from various hard woods, and finished by spraying with a series of stains, sealers, and/or paints. Spraying was done in a spray booth. General area and personal breathing zone air samples were collected, and the ventilation system was evaluated. The authors conclude that a potential hazard existed due to airborne exposure to hexavalent chromium (7440473), formaldehyde (50000) and ethylene-glycol-monobutyl-ether (111762) in the cabinet finishing area. A lack of makeup air, ineffective use of exhaust ventilation systems, and uncontrolled contamination sources were several of the problems causing employee exposure. The authors recommend specific measures to minimize and reduce exposure to hexavalent chromium compounds and formaldehyde, and to improve the ventilation systems at the facility.","Health Hazard Evaluation Report HETA 88-068-2077, Schmidt Cabinet Company, New Salisbury, Indiana Abs: In response to a request from the Schmidt Cabinet Company (SIC-2434), New Salisbury, Indiana, an investigation was undertaken of the exhaust ventilation system and finishing room exposures. The firm manufactured kitchen cabinets and bathroom vanities. Approximately 90 workers were employed at the facility. The cabinets were made from various hard woods, and finished by spraying with a series of stains, sealers, and/or paints. Spraying was done in a spray booth. General area and personal breathing zone air samples were collected, and the ventilation system was evaluated. The authors conclude that a potential hazard existed due to airborne exposure to hexavalent chromium (7440473), formaldehyde (50000) and ethylene-glycol-monobutyl-ether (111762) in the cabinet finishing area. A lack of makeup air, ineffective use of exhaust ventilation systems, and uncontrolled contamination sources were several of the problems causing employee exposure. The authors recommend specific measures to minimize and reduce exposure to hexavalent chromium compounds and formaldehyde, and to improve the ventilation systems at the facility."
1510131,Muirhead and  Carrier 2012,"Comparison of Four Strong Acids on the Precipitation Potential of Gypsum in Brines During Distillation of Pretreated, Augmented Urine","Text in English. Presented at ICES 2012, San Diego, CA, United States, 15-19 Jul. 2012. Publicly available Unlimited. CASI. s study, three different mineral acids were substituted for sulfuric acid (H2SO4) in the urine stabilizer solution to eliminate the excess of sulfate ions in pretreated urine and assess the impact on maximum water recovery to avoid precipitation of minerals during distillation. The study evaluated replacing 98% sulfuric acid with 85% phosphoric acid (H3PO4), 37% hydrochloric acid (HCl), or 70% nitric acid (HNO3). The effect of lowering the oxidizer concentration in the pretreatment formulation also was studied. This paper summarizes the test results, defines candidate formulations for further study, and specifies the injection masses required to stabilize urine and minimize the risk of mineral precipitation during distillation. In the first test with a brine ersatz acidified with different acids, the solubility of calcium in gypsum saturated solutions was measured. The solubility of gypsum was doubled in the brines acidified with the alternative acids compared to sulfuric acid. In a second series of tests, the alternative acid pretreatment concentrations were effective at preventing precipitation of gypsum and other minerals up to 85% water recovery from 95th-percentile pretreated, augmented urine. Based on test results, phosphoric acid is recommended as the safest alternative to sulfuric acid. It also is recommended that the injected mass concentration of chromium trioxide solution be reduced by 75% to minimize liquid resupply mass by about 50%, reduce toxicity of brines, and reduce the concentration of organic acids in distillate. The new stabilizer solution formulations and required doses to stabilize urine and prevent precipitation of minerals up to 85% water recovery are given. The formulations in this study were tested on a limited number of artificially augmented urine batches collected from employees at the Johnson Space Center (JSC). This study successfully demonstrated that the desired physical and chemical stability of pretreated urine and brines can be achieved using alternate pretreatment formulations under laboratory conditions. Additional testing and hazard assessments will be required to determine the feasibility of utilizing the proposed urine pretreatment formulations on ISS.","Comparison of Four Strong Acids on the Precipitation Potential of Gypsum in Brines During Distillation of Pretreated, Augmented Urine Abs: Text in English. Presented at ICES 2012, San Diego, CA, United States, 15-19 Jul. 2012. Publicly available Unlimited. CASI. s study, three different mineral acids were substituted for sulfuric acid (H2SO4) in the urine stabilizer solution to eliminate the excess of sulfate ions in pretreated urine and assess the impact on maximum water recovery to avoid precipitation of minerals during distillation. The study evaluated replacing 98% sulfuric acid with 85% phosphoric acid (H3PO4), 37% hydrochloric acid (HCl), or 70% nitric acid (HNO3). The effect of lowering the oxidizer concentration in the pretreatment formulation also was studied. This paper summarizes the test results, defines candidate formulations for further study, and specifies the injection masses required to stabilize urine and minimize the risk of mineral precipitation during distillation. In the first test with a brine ersatz acidified with different acids, the solubility of calcium in gypsum saturated solutions was measured. The solubility of gypsum was doubled in the brines acidified with the alternative acids compared to sulfuric acid. In a second series of tests, the alternative acid pretreatment concentrations were effective at preventing precipitation of gypsum and other minerals up to 85% water recovery from 95th-percentile pretreated, augmented urine. Based on test results, phosphoric acid is recommended as the safest alternative to sulfuric acid. It also is recommended that the injected mass concentration of chromium trioxide solution be reduced by 75% to minimize liquid resupply mass by about 50%, reduce toxicity of brines, and reduce the concentration of organic acids in distillate. The new stabilizer solution formulations and required doses to stabilize urine and prevent precipitation of minerals up to 85% water recovery are given. The formulations in this study were tested on a limited number of artificially augmented urine batches collected from employees at the Johnson Space Center (JSC). This study successfully demonstrated that the desired physical and chemical stability of pretreated urine and brines can be achieved using alternate pretreatment formulations under laboratory conditions. Additional testing and hazard assessments will be required to determine the feasibility of utilizing the proposed urine pretreatment formulations on ISS."
1510130,Wingard 2003,Compatibility Testing of Polymeric Materials for the Urine Processor Assembly (UPA) of International Space Station (ISS),"Presented at North American Thermal Analysis Society Conference, Albuquerque, NM, United States, 22-24 Sep. 2003. Publicly available Unlimited. CASI. International Space Station (ISS), astronauts will convert urine into potable water with the Urine Processor Assembly (UPA) by a distillation process. The urine is pre-treated, containing flush water and stabilizers. About 2.5% solids in the urine are concentrated up to 16% brine through distillation. Dynamic mechanical analysis (DMA) in the stress relaxation mode was primarily used to test 15 polymeric UPA materials for compatibility with the pre-treated and brine solutions. There were concerns that chromium trioxide (CrO3), a stabilizer not in the original pre-treat formulation for similar compatibility testing in 2000, could have an adverse effect on these polymers. DMA testing is partially complete for polymeric material samples immersed in the two solutions at room temperature for as long as 200 days. By comparing each material (conditioned and virgin), the stress relaxation modulus (E) was determined for short-term use and predicted for as long as a 10-year use in space. Such a delta E showed a decrease of as much as 79% for a Nylon material, but an increase as much as 454% for a polysulfone material, with increasing immersion time.","Compatibility Testing of Polymeric Materials for the Urine Processor Assembly (UPA) of International Space Station (ISS) Abs: Presented at North American Thermal Analysis Society Conference, Albuquerque, NM, United States, 22-24 Sep. 2003. Publicly available Unlimited. CASI. International Space Station (ISS), astronauts will convert urine into potable water with the Urine Processor Assembly (UPA) by a distillation process. The urine is pre-treated, containing flush water and stabilizers. About 2.5% solids in the urine are concentrated up to 16% brine through distillation. Dynamic mechanical analysis (DMA) in the stress relaxation mode was primarily used to test 15 polymeric UPA materials for compatibility with the pre-treated and brine solutions. There were concerns that chromium trioxide (CrO3), a stabilizer not in the original pre-treat formulation for similar compatibility testing in 2000, could have an adverse effect on these polymers. DMA testing is partially complete for polymeric material samples immersed in the two solutions at room temperature for as long as 200 days. By comparing each material (conditioned and virgin), the stress relaxation modulus (E) was determined for short-term use and predicted for as long as a 10-year use in space. Such a delta E showed a decrease of as much as 79% for a Nylon material, but an increase as much as 454% for a polysulfone material, with increasing immersion time."
1510129,Kamenetzky et al. 1995,Evaluation of Thermal Control Coatings and Polymeric Materials Exposed to Ground Simulated Atomic Oxygen and Vacuum Ultraviolet Radiation,"N96-29631 is the same number as N19960029068. us thermal control and polymeric samples with potential International Space Station applications were evaluated for atomic oxygen and vacuum ultraviolet radiation effects. Included in this study were samples of various anodized aluminum samples, ceramic paints, polymeric materials, and beta cloth, a Teflon-impregnated fiberglass cloth. Aluminum anodizations tested were black duranodic, chromic acid anodize, and sulfuric acid anodize. Paint samples consisted of an inorganic glassy black paint and Z-93 white paint made with the original PS7 binder and the new K2130 binder. Polymeric samples evaluated included bulk Halar, bulk PEEK, and silverized FEP Teflon. Aluminized and nonaluminized Chemfab 250 beta cloth were also exposed. Samples were evaluated for changes in mass, thickness, solar absorptance, and infrared emittance. In addition to material effects, an investigation was made comparing diffuse reflectance/solar absorptance measurements made using a Beckman DK2 spectroreflectometer and like measurements made using an AZ Technology-developed laboratory portable spectroreflectometer.","Evaluation of Thermal Control Coatings and Polymeric Materials Exposed to Ground Simulated Atomic Oxygen and Vacuum Ultraviolet Radiation Abs: N96-29631 is the same number as N19960029068. us thermal control and polymeric samples with potential International Space Station applications were evaluated for atomic oxygen and vacuum ultraviolet radiation effects. Included in this study were samples of various anodized aluminum samples, ceramic paints, polymeric materials, and beta cloth, a Teflon-impregnated fiberglass cloth. Aluminum anodizations tested were black duranodic, chromic acid anodize, and sulfuric acid anodize. Paint samples consisted of an inorganic glassy black paint and Z-93 white paint made with the original PS7 binder and the new K2130 binder. Polymeric samples evaluated included bulk Halar, bulk PEEK, and silverized FEP Teflon. Aluminized and nonaluminized Chemfab 250 beta cloth were also exposed. Samples were evaluated for changes in mass, thickness, solar absorptance, and infrared emittance. In addition to material effects, an investigation was made comparing diffuse reflectance/solar absorptance measurements made using a Beckman DK2 spectroreflectometer and like measurements made using an AZ Technology-developed laboratory portable spectroreflectometer."
1510128,Kallenborn and  Emmons 1995,Thin-Film Sulfuric Acid Anodizing as a Replacement for Chromic Acid Anodizing,"In NASA. Marshall Space Flight Center, Aerospace Environmental Technology Conference p 267-276. c acid has long been used to produce a thin, corrosion resistant (Type I) coating on aluminum. Following anodizing, the hardware was sealed using a sodium dichromate solution. Sealing closes up pores inherent in the anodized coating, thus improving corrosion resistance. The thinness of the brittle coating is desirable from a fatigue standpoint, and chromium was absorbed by the coating during the sealing process, further improving corrosion resistance. Unfortunately, both chromic acid and sodium dichromate contain carcinogenic hexavalent chromium. Sulfuric acid is being considered as a replacement for chromic acid. Sulfuric acid of 10-20 percent concentration has traditionally been used to produce relatively thick (Types II and III) or abrasion resistant (Type III) coatings. A more dilute, that is five weight percent, sulfuric acid anodizing process, which produces a thinner coating than Type II or III, with nickel acetate as the sealant has been developed. The process was evaluated in regard to corrosion resistance, throwing power, fatigue life, and processing variable sensitivity, and shows promise as a replacement for the chromic acid process.","Thin-Film Sulfuric Acid Anodizing as a Replacement for Chromic Acid Anodizing Abs: In NASA. Marshall Space Flight Center, Aerospace Environmental Technology Conference p 267-276. c acid has long been used to produce a thin, corrosion resistant (Type I) coating on aluminum. Following anodizing, the hardware was sealed using a sodium dichromate solution. Sealing closes up pores inherent in the anodized coating, thus improving corrosion resistance. The thinness of the brittle coating is desirable from a fatigue standpoint, and chromium was absorbed by the coating during the sealing process, further improving corrosion resistance. Unfortunately, both chromic acid and sodium dichromate contain carcinogenic hexavalent chromium. Sulfuric acid is being considered as a replacement for chromic acid. Sulfuric acid of 10-20 percent concentration has traditionally been used to produce relatively thick (Types II and III) or abrasion resistant (Type III) coatings. A more dilute, that is five weight percent, sulfuric acid anodizing process, which produces a thinner coating than Type II or III, with nickel acetate as the sealant has been developed. The process was evaluated in regard to corrosion resistance, throwing power, fatigue life, and processing variable sensitivity, and shows promise as a replacement for the chromic acid process."
1510127,Cromwell et al. 1993,Spectral Infrared Hemispherical Reflectance Measurements for LDEF Tray Clamps,"In NASA. Langley Research Center, Ldef: 69 Months in Space. Part 3: Second Post-Retrieval Symposium p 1001-1014. ed hemispherical reflectance measurements that were made on 58 chromic acid anodized tray clamps from LDEF are described. The measurements were made using a hemiellipsoidal mirror reflectometer with interferometer for wavelengths between 2-15 microns. The tray clamps investigated were from locations about the entire spacecraft and provided the opportunity for comparing the effects of atomic oxygen at each location. Results indicate there was essentially no dependence on atomic oxygen fluence for the surfaces studied, but there did appear to be a slight dependence on solar radiation exposure. The reflectances of the front sides of the tray clamps consistently were slightly higher than for the protected rear tray clamp surfaces.","Spectral Infrared Hemispherical Reflectance Measurements for LDEF Tray Clamps Abs: In NASA. Langley Research Center, Ldef: 69 Months in Space. Part 3: Second Post-Retrieval Symposium p 1001-1014. ed hemispherical reflectance measurements that were made on 58 chromic acid anodized tray clamps from LDEF are described. The measurements were made using a hemiellipsoidal mirror reflectometer with interferometer for wavelengths between 2-15 microns. The tray clamps investigated were from locations about the entire spacecraft and provided the opportunity for comparing the effects of atomic oxygen at each location. Results indicate there was essentially no dependence on atomic oxygen fluence for the surfaces studied, but there did appear to be a slight dependence on solar radiation exposure. The reflectances of the front sides of the tray clamps consistently were slightly higher than for the protected rear tray clamp surfaces."
1510126,Truex and  Vermeul 2012,Sampling Instruction: Investigation of Hexavalent Chromium Flux to Groundwater at the 100-C-7:1 Excavation Site,"Sponsored by Department of Energy, Washington, DC. l types of data are needed to assess the flux of Cr(VI) from the excavation into the groundwater. As described in this plan, these data include (1) temporal Cr(VI) data in the shallow groundwater beneath the pit; (2) hydrologic data to interpret groundwater flow and contaminant transport; (3) hydraulic gradient data; and (4) as a contingency action if necessary, vertical profiling of Cr(VI) concentrations in the shallow aquifer beyond the depth possible with aquifer tubes.","Sampling Instruction: Investigation of Hexavalent Chromium Flux to Groundwater at the 100-C-7:1 Excavation Site Abs: Sponsored by Department of Energy, Washington, DC. l types of data are needed to assess the flux of Cr(VI) from the excavation into the groundwater. As described in this plan, these data include (1) temporal Cr(VI) data in the shallow groundwater beneath the pit; (2) hydrologic data to interpret groundwater flow and contaminant transport; (3) hydraulic gradient data; and (4) as a contingency action if necessary, vertical profiling of Cr(VI) concentrations in the shallow aquifer beyond the depth possible with aquifer tubes."
1510125,Smoot 2010,Aquifer Testing and Rebound Study in Support of the 100-H Deep Chromium Investigation,"Sponsored by Department of Energy, Washington, DC. 0-HR-3 Groundwater Operable Unit (OU) second Comprehensive Environmental Response, Compensation, and Liability Act of 1980 (CERCLA) 5-year review (DOEIRL-2006-20, The Second CERCLA Five-Year Review Report for the Hanford Site) set a milestone to conduct an investigation of deep hexavalent chromium contamination in the sediments of the Ringold upper mud (RUM) unit, which underlies the unconfined aquifer in the 100-H Area. The 5-year review noted that groundwater samples from one deep well extending below the aquitard (i.e., RUM) exceeded both the groundwater standard of 48 parts per billion (ppb) (Ecology Publication 94-06, Model Toxics Control Act Cleanup Statute and Regulation) and the federal drinking water standard of 100 (mu)g/L for hexavalent chromium. The extent of hexavalent chromium contamination in this zone is not well understood. Action 12-1 from the 5-year review is to perform additional characterization of the aquifer below the initial aquitard. Field characterization and aquifer testing were performed in the Hanford Site's 100-H Area to address this milestone. The aquifer tests were conducted to gather data to answer several fundamental questions regarding the presence of the hexavalent chromium in the deep sediments of the RUM and to determine the extent and magnitude of deeper contamination. The pumping tests were performed in accordance with the Description of Work for Aquifer Testing in Support of the 100-H Deep Chromium Investigation (SGW-41302). The specific objectives for the series of tests were as follows: (1) Evaluate the sustainable production of the subject wells using step-drawdown and constant-rate pumping tests. (2) Collect water-level data to evaluate the degree of hydraulic connection between the RUM and the unconfined (upper) aquifer (natural or induced along the well casing). (3) Evaluate the hydraulic properties of a confined permeable layer within the RUM.; (4) Collect time-series groundwater samples during testing to evaluate the extent and persistence of hexavalent chromium in the deeper zones. Use data collected to refine the current conceptual model for the 100-H Area unconfined aquifer and the RUM in this area. (5) Evaluate the concentration 'rebound' in the unconfined aquifer of hexavalent chromium and the contaminants of concern during shutdown of the extraction wells.","Aquifer Testing and Rebound Study in Support of the 100-H Deep Chromium Investigation Abs: Sponsored by Department of Energy, Washington, DC. 0-HR-3 Groundwater Operable Unit (OU) second Comprehensive Environmental Response, Compensation, and Liability Act of 1980 (CERCLA) 5-year review (DOEIRL-2006-20, The Second CERCLA Five-Year Review Report for the Hanford Site) set a milestone to conduct an investigation of deep hexavalent chromium contamination in the sediments of the Ringold upper mud (RUM) unit, which underlies the unconfined aquifer in the 100-H Area. The 5-year review noted that groundwater samples from one deep well extending below the aquitard (i.e., RUM) exceeded both the groundwater standard of 48 parts per billion (ppb) (Ecology Publication 94-06, Model Toxics Control Act Cleanup Statute and Regulation) and the federal drinking water standard of 100 (mu)g/L for hexavalent chromium. The extent of hexavalent chromium contamination in this zone is not well understood. Action 12-1 from the 5-year review is to perform additional characterization of the aquifer below the initial aquitard. Field characterization and aquifer testing were performed in the Hanford Site's 100-H Area to address this milestone. The aquifer tests were conducted to gather data to answer several fundamental questions regarding the presence of the hexavalent chromium in the deep sediments of the RUM and to determine the extent and magnitude of deeper contamination. The pumping tests were performed in accordance with the Description of Work for Aquifer Testing in Support of the 100-H Deep Chromium Investigation (SGW-41302). The specific objectives for the series of tests were as follows: (1) Evaluate the sustainable production of the subject wells using step-drawdown and constant-rate pumping tests. (2) Collect water-level data to evaluate the degree of hydraulic connection between the RUM and the unconfined (upper) aquifer (natural or induced along the well casing). (3) Evaluate the hydraulic properties of a confined permeable layer within the RUM.; (4) Collect time-series groundwater samples during testing to evaluate the extent and persistence of hexavalent chromium in the deeper zones. Use data collected to refine the current conceptual model for the 100-H Area unconfined aquifer and the RUM in this area. (5) Evaluate the concentration 'rebound' in the unconfined aquifer of hexavalent chromium and the contaminants of concern during shutdown of the extraction wells."
1510124,Lindberg 2010,"Physical Property Analysis and Report for Sediments at 100-BC-5 Operable Unit, Boreholes C7505, C7506, C7507, and C7665","Sponsored by Department of Energy, Washington, DC. n October 14, 2009 and February 22, 2010 sediment samples were received from 100-BC Decision Unit for geochemical studies. This is an analytical data report for sediments received from CHPRC at the 100 BC 5 OU. The analyses for this project were performed at the 325 building located in the 300 Area of the Hanford Site. The analyses were performed according to Pacific Northwest National Laboratory (PNNL) approved procedures and/or nationally recognized test procedures. The data sets include the sample identification numbers, analytical results, estimated quantification limits (EQL), and quality control data. The preparatory and analytical quality control requirements, calibration requirements, acceptance criteria, and failure actions are defined in the on-line QA plan 'Conducting Analytical Work in Support of Regulatory Programs' (CAW). This QA plan implements the Hanford Analytical Services Quality Assurance Requirements Documents (HASQARD) for PNNL.","Physical Property Analysis and Report for Sediments at 100-BC-5 Operable Unit, Boreholes C7505, C7506, C7507, and C7665 Abs: Sponsored by Department of Energy, Washington, DC. n October 14, 2009 and February 22, 2010 sediment samples were received from 100-BC Decision Unit for geochemical studies. This is an analytical data report for sediments received from CHPRC at the 100 BC 5 OU. The analyses for this project were performed at the 325 building located in the 300 Area of the Hanford Site. The analyses were performed according to Pacific Northwest National Laboratory (PNNL) approved procedures and/or nationally recognized test procedures. The data sets include the sample identification numbers, analytical results, estimated quantification limits (EQL), and quality control data. The preparatory and analytical quality control requirements, calibration requirements, acceptance criteria, and failure actions are defined in the on-line QA plan 'Conducting Analytical Work in Support of Regulatory Programs' (CAW). This QA plan implements the Hanford Analytical Services Quality Assurance Requirements Documents (HASQARD) for PNNL."
1510123,Qafoku et al. 2011,Geochemical Characterization of Chromate Contamination in the 100 Area Vadose Zone at the Hanford Site - Part 2,"Sponsored by Department of Energy, Washington, DC. Hanford Site, chromate was used throughout the 100 Areas (100-B, 100-C, 100-D/DR, 100-F, 100-H, and 100 K) as a corrosion inhibitor in reactor cooling water. Chromate was delivered in rail cars, tanker trucks, barrels, and local pipelines as dichromate granular solid or stock solution. In many occasions, chromate was inevitably discharged to surface or near-surface ground through spills during handling, pipeline leaks, or during disposal to cribs. The composition of the liquids that were discharged is not known and it is quite possible that Cr(VI) fate and transport in the contaminated sediments would be a function of the chemical composition of the waste fluids. The major objectives of this investigation which was limited in scope by the financial resources available, were to (1) determine the leaching characteristics of hexavalent chromium (Cr(VI)) from contaminated sediments collected from 100-D Area spill sites; (2) elucidate possible Cr(VI) mineral and/or chemical associations that may be responsible for Cr(VI) retention in the Hanford Site 100 Areas through the use of macroscopic leaching studies, and microscale characterization of contaminated sediments; and (3) provide information to construct a conceptual model of Cr(VI) geochemistry in the Hanford 100 Area vadose zone that can be used for developing options for environmental remediation. The information gathered from this research effort will help to further improve our understanding of Cr(VI) behavior in the vadose zone and will also help in accelerating the 100 Area Columbia River Corridor cleanup by providing valuable information to develop remedial action based on a fundamental understanding of Cr(VI) vadose zone geochemistry. A series of column experiments were conducted with contaminated sediments to study Cr(VI) desorption patterns. Column experiments used the field size fraction of the sediment samples and a simulated Hanford Site groundwater solution. Periodic stop flow events were applied to evaluate the change in elemental concentration during time periods of no flow and greater fluid residence time. Sediments were characterized for the spatial and mineralogical associations of the contamination using some microscale techniques such as X-ray diffraction, scanning electron microscopy, energy dispersive spectroscopy, X-ray photoelectron spectroscopy, and Mossbauer spectroscopy.","Geochemical Characterization of Chromate Contamination in the 100 Area Vadose Zone at the Hanford Site - Part 2 Abs: Sponsored by Department of Energy, Washington, DC. Hanford Site, chromate was used throughout the 100 Areas (100-B, 100-C, 100-D/DR, 100-F, 100-H, and 100 K) as a corrosion inhibitor in reactor cooling water. Chromate was delivered in rail cars, tanker trucks, barrels, and local pipelines as dichromate granular solid or stock solution. In many occasions, chromate was inevitably discharged to surface or near-surface ground through spills during handling, pipeline leaks, or during disposal to cribs. The composition of the liquids that were discharged is not known and it is quite possible that Cr(VI) fate and transport in the contaminated sediments would be a function of the chemical composition of the waste fluids. The major objectives of this investigation which was limited in scope by the financial resources available, were to (1) determine the leaching characteristics of hexavalent chromium (Cr(VI)) from contaminated sediments collected from 100-D Area spill sites; (2) elucidate possible Cr(VI) mineral and/or chemical associations that may be responsible for Cr(VI) retention in the Hanford Site 100 Areas through the use of macroscopic leaching studies, and microscale characterization of contaminated sediments; and (3) provide information to construct a conceptual model of Cr(VI) geochemistry in the Hanford 100 Area vadose zone that can be used for developing options for environmental remediation. The information gathered from this research effort will help to further improve our understanding of Cr(VI) behavior in the vadose zone and will also help in accelerating the 100 Area Columbia River Corridor cleanup by providing valuable information to develop remedial action based on a fundamental understanding of Cr(VI) vadose zone geochemistry. A series of column experiments were conducted with contaminated sediments to study Cr(VI) desorption patterns. Column experiments used the field size fraction of the sediment samples and a simulated Hanford Site groundwater solution. Periodic stop flow events were applied to evaluate the change in elemental concentration during time periods of no flow and greater fluid residence time. Sediments were characterized for the spatial and mineralogical associations of the contamination using some microscale techniques such as X-ray diffraction, scanning electron microscopy, energy dispersive spectroscopy, X-ray photoelectron spectroscopy, and Mossbauer spectroscopy."
1510122,Baker 1964,Environmental Monitoring Summary for Paducah Plant for 1962 and 1963,"Sponsored by Department of Energy, Washington, DC. ducah Plant is a government-owned gaseous diffusion plant operated by Union Carbide Corporation, Nuclear Division, for the Atomic Energy Commission. In addition to the uranium hexafluoride in the isotope separation cascade, large quantities of uranium fluorides and oxides are processed in the feed manufacturing plant and in the uranium metal foundry. Significant quantities of hexavalent chromium are used each day as a corrosion inhibitor in the recirculating water of the plant cooling system. Therefore, uranium, fluorides, and hexavalent chromium are of primary interest in the environmental monitoring program of the Paducah Plant. Other factors routinely checked are pH, beta activity, and background gamma radiation. Air and water are sampled continuously in the vicinity of the plant, and grab samples of Ohio River water and vegetation samples are collected monthly.","Environmental Monitoring Summary for Paducah Plant for 1962 and 1963 Abs: Sponsored by Department of Energy, Washington, DC. ducah Plant is a government-owned gaseous diffusion plant operated by Union Carbide Corporation, Nuclear Division, for the Atomic Energy Commission. In addition to the uranium hexafluoride in the isotope separation cascade, large quantities of uranium fluorides and oxides are processed in the feed manufacturing plant and in the uranium metal foundry. Significant quantities of hexavalent chromium are used each day as a corrosion inhibitor in the recirculating water of the plant cooling system. Therefore, uranium, fluorides, and hexavalent chromium are of primary interest in the environmental monitoring program of the Paducah Plant. Other factors routinely checked are pH, beta activity, and background gamma radiation. Air and water are sampled continuously in the vicinity of the plant, and grab samples of Ohio River water and vegetation samples are collected monthly."
1510120,Chakraborty 2008,Integrated Ecogenomics Study for Bioremediation of Cr(VI) at Hanford 100H Area,"Sponsored by Department of Energy, Washington, DC. lent chromium is a widespread contaminant found in groundwater. In order to stimulate microbially mediated Cr(VI)-reduction, a poly-lactate compound was injected into Cr(VI)-contaminated aquifers at site 100H at Hanford. Investigation of bacterial community composition using high-density DNA microarray analysis of 16S rRNA gene products revealed a stimulation of Pseudomonas, Desulfovibrio and Geobacter species amongst others. Enrichment of these organisms coincided with continued Cr(VI) depletion. Functional gene-array analysis of DNA from monitoring well indicated high abundance of genes involved in nitrate-reduction, sulfate-reduction, iron-reduction, methanogenesis, chromium tolerance/reduction. Clone-library data revealed Psedomonas was the dominant genus in these samples. Based on above results, we conducted lab investigations to study the dominant anaerobic culturable microbial populations present at this site and their role in Cr(VI)-reduction. Enrichments using defined anaerobic media resulted in isolation of an iron-reducing, a sulfate-reducing and a nitrate-reducing isolate among several others. Preliminary 16S rDNA sequence analysis identified the isolates as Geobacter metallireducens, Pseudomonas stutzeri and Desulfovibrio vulgaris species respectively. The Pseudomonas isolate utilized acetate, lactate, glycerol and pyruvate as alternative carbon sources, and reduced Cr(VI). Anaerobic washed cell suspension of strain HLN reduced almost 95M Cr(VI) within 4 hr.","Integrated Ecogenomics Study for Bioremediation of Cr(VI) at Hanford 100H Area Abs: Sponsored by Department of Energy, Washington, DC. lent chromium is a widespread contaminant found in groundwater. In order to stimulate microbially mediated Cr(VI)-reduction, a poly-lactate compound was injected into Cr(VI)-contaminated aquifers at site 100H at Hanford. Investigation of bacterial community composition using high-density DNA microarray analysis of 16S rRNA gene products revealed a stimulation of Pseudomonas, Desulfovibrio and Geobacter species amongst others. Enrichment of these organisms coincided with continued Cr(VI) depletion. Functional gene-array analysis of DNA from monitoring well indicated high abundance of genes involved in nitrate-reduction, sulfate-reduction, iron-reduction, methanogenesis, chromium tolerance/reduction. Clone-library data revealed Psedomonas was the dominant genus in these samples. Based on above results, we conducted lab investigations to study the dominant anaerobic culturable microbial populations present at this site and their role in Cr(VI)-reduction. Enrichments using defined anaerobic media resulted in isolation of an iron-reducing, a sulfate-reducing and a nitrate-reducing isolate among several others. Preliminary 16S rDNA sequence analysis identified the isolates as Geobacter metallireducens, Pseudomonas stutzeri and Desulfovibrio vulgaris species respectively. The Pseudomonas isolate utilized acetate, lactate, glycerol and pyruvate as alternative carbon sources, and reduced Cr(VI). Anaerobic washed cell suspension of strain HLN reduced almost 95M Cr(VI) within 4 hr."
1510119,Bieniosek et al. 2006,Comments on Cathode Contaminants and the LBNL Test Stand,"Sponsored by Department of Energy, Washington, DC. eport collects information on cathode contaminants we have gathered in the process of operating the LBNL DARHT cathode test stand. Information on contaminants is compiled from several sources. The attachment, 'Practical Aspects of Modern Dispenser Cathodes', is from Heat Wave Corp. (TB-134) and was originally published in Microwave Journal, September 1979. Cathode contamination depends on both material choices and residual gases. Table 1 of TB-134 lists materials that can poison dispenser cathodes. These include reactive residual gases or vapors such as oxygen, water vapor, benzene, chlorine, fluorine, sulfur, silicon, and most metals other than molybdenum, rhenium, tungsten, and copper. The metals interact with the cathode surface through their vapor pressure. A paper by Nexsen and Turner, J. Appl. Phys. 68, 298-303 (1990) shows the threshold effects of some common residual gases or vapors on cathode performance. The book by Walter H. Kohl, Handbook of Materials and Techniques for Vacuum Devices, also contains useful information on cathodes and poisoning agents. A plot of the vapor pressures and poisoning effect of certain metals (from Kohl) is shown below. Note that the vapor pressure of zinc is 1.1 x 10(sup -8) Torr at 400 K = 127 C, and 2.7 x 10(sup -5) at 500 K = 227 C. By contrast iron reaches a vapor pressure 1 x 10(sup -8) between 800 and 900 C. Therefore it is important to eliminate any brass parts that could exceed a temperature of 100 C.","Comments on Cathode Contaminants and the LBNL Test Stand Abs: Sponsored by Department of Energy, Washington, DC. eport collects information on cathode contaminants we have gathered in the process of operating the LBNL DARHT cathode test stand. Information on contaminants is compiled from several sources. The attachment, 'Practical Aspects of Modern Dispenser Cathodes', is from Heat Wave Corp. (TB-134) and was originally published in Microwave Journal, September 1979. Cathode contamination depends on both material choices and residual gases. Table 1 of TB-134 lists materials that can poison dispenser cathodes. These include reactive residual gases or vapors such as oxygen, water vapor, benzene, chlorine, fluorine, sulfur, silicon, and most metals other than molybdenum, rhenium, tungsten, and copper. The metals interact with the cathode surface through their vapor pressure. A paper by Nexsen and Turner, J. Appl. Phys. 68, 298-303 (1990) shows the threshold effects of some common residual gases or vapors on cathode performance. The book by Walter H. Kohl, Handbook of Materials and Techniques for Vacuum Devices, also contains useful information on cathodes and poisoning agents. A plot of the vapor pressures and poisoning effect of certain metals (from Kohl) is shown below. Note that the vapor pressure of zinc is 1.1 x 10(sup -8) Torr at 400 K = 127 C, and 2.7 x 10(sup -5) at 500 K = 227 C. By contrast iron reaches a vapor pressure 1 x 10(sup -8) between 800 and 900 C. Therefore it is important to eliminate any brass parts that could exceed a temperature of 100 C."
1510118,Petersen et al. 2005,Mending the In Situ Redox Manipulation Barrier,"Sponsored by Department of Energy, Washington, DC. ly 2004, the U.S. Department of Energy (DOE) Richland and Fluor Hanford requested technical assistance from the DOE Headquarters EM-23 Technical Assistance Program to provide a team of technical experts to develop recommendations for mending the In Situ Redox Manipulation (ISRM) Barrier in the 100-D Area of the Hanford Site in Washington State. To accommodate this request, EM-23 provided support to convene a group of technical experts from industry, a national laboratory, and a DOE site to participate in a 2 1/2-day workshop with the objective of identifying and recommending options to enhance the performance of the 100-D Area reactive barrier and of a planned extension to the northeast. This report provides written documentation of the team's findings and recommendations. In 1995, a plume of dissolved hexavalent chromium (Cr(VI)), which resulted from operation of the D/DR Reactors at the Hanford site, was discovered along the Columbia River shoreline and in the 100-D Area. Between 1999 and 2003, a reactive barrier using the In Situ Redox Manipulation (ISRM) technology, was installed a distance of 680 meters along the river to reduce the Cr(VI) in the groundwater. The ISRM technology creates a treatment zone within the aquifer by injection of sodium dithionite, a strong reducing agent that scavenges dissolved oxygen (DO) from the aquifer and reduces ferric iron (Fe(III)), related metals, and oxy-ions. The reduction of Fe(III) to ferrous (Fe(II)) iron provides the primary reduction capacity to reduce Cr(VI) to the +3 state, which is less mobile and less toxic. Bench-scale and field-scale treatability tests were initially conducted to demonstrate proof-of principle and to provide data for estimation of barrier longevity. These calculations estimated barrier longevity in excess of twenty years. However, several years after initial and secondary treatment, groundwater in a number of wells has been found to contain elevated chromium (Cr) concentrations, indicating some loss of reductive capacity within the aquifer. The Technical Assistance Team (TAT) was requested to perform the following activities: (1) evaluate the most probable condition(s) that has led to the presence of Cr(VI) in 12 different barrier wells (i.e. premature loss of reductive capacity), (2) recommend methods for determining the cause of the problem, (3) recommend methods for evaluating the magnitude of the problem, (4) recommend practicable method(s) for mending the barrier that involves a long-term solution, and (5) recommend methods for extending the barrier to the northeast (e.g., changing injection procedure, changing or augmenting the injected material). Since the March 2004 workshop, a decision has been made to place a hold on the barrier extension until more is known about the cause of the problem. However, the report complies with the original request for information on all of the above activities, but focuses on determining the cause of the problem and mending of the existing barrier.","Mending the In Situ Redox Manipulation Barrier Abs: Sponsored by Department of Energy, Washington, DC. ly 2004, the U.S. Department of Energy (DOE) Richland and Fluor Hanford requested technical assistance from the DOE Headquarters EM-23 Technical Assistance Program to provide a team of technical experts to develop recommendations for mending the In Situ Redox Manipulation (ISRM) Barrier in the 100-D Area of the Hanford Site in Washington State. To accommodate this request, EM-23 provided support to convene a group of technical experts from industry, a national laboratory, and a DOE site to participate in a 2 1/2-day workshop with the objective of identifying and recommending options to enhance the performance of the 100-D Area reactive barrier and of a planned extension to the northeast. This report provides written documentation of the team's findings and recommendations. In 1995, a plume of dissolved hexavalent chromium (Cr(VI)), which resulted from operation of the D/DR Reactors at the Hanford site, was discovered along the Columbia River shoreline and in the 100-D Area. Between 1999 and 2003, a reactive barrier using the In Situ Redox Manipulation (ISRM) technology, was installed a distance of 680 meters along the river to reduce the Cr(VI) in the groundwater. The ISRM technology creates a treatment zone within the aquifer by injection of sodium dithionite, a strong reducing agent that scavenges dissolved oxygen (DO) from the aquifer and reduces ferric iron (Fe(III)), related metals, and oxy-ions. The reduction of Fe(III) to ferrous (Fe(II)) iron provides the primary reduction capacity to reduce Cr(VI) to the +3 state, which is less mobile and less toxic. Bench-scale and field-scale treatability tests were initially conducted to demonstrate proof-of principle and to provide data for estimation of barrier longevity. These calculations estimated barrier longevity in excess of twenty years. However, several years after initial and secondary treatment, groundwater in a number of wells has been found to contain elevated chromium (Cr) concentrations, indicating some loss of reductive capacity within the aquifer. The Technical Assistance Team (TAT) was requested to perform the following activities: (1) evaluate the most probable condition(s) that has led to the presence of Cr(VI) in 12 different barrier wells (i.e. premature loss of reductive capacity), (2) recommend methods for determining the cause of the problem, (3) recommend methods for evaluating the magnitude of the problem, (4) recommend practicable method(s) for mending the barrier that involves a long-term solution, and (5) recommend methods for extending the barrier to the northeast (e.g., changing injection procedure, changing or augmenting the injected material). Since the March 2004 workshop, a decision has been made to place a hold on the barrier extension until more is known about the cause of the problem. However, the report complies with the original request for information on all of the above activities, but focuses on determining the cause of the problem and mending of the existing barrier."
1510117,Day et al. 2003,"Iron Phosphate Glasses: An Alernative for Vitrifying Certain Nuclear Wastes. (Report for June 16, 2002 to June 15, 2003)","Annual rept. red by Department of Energy, Washington, DC. the past year, iron phosphate glasses containing the following three types of nuclear waste, as recommended by the Tank Focus Area (TFA) group, have been investigated. (1) a high sodium/sulfate Hanford Low-Activity Waste (LAW) (2) a High Chrome Waste (HCW) at Hanford, and (3) a Sodium Bearing Waste (SBW) at Idaho National Engineering and Environmental Laboratory (INEEL) Over three hundred trial melts, ranging in size from 50 g to more than 10 kg, have been evaluated. The experimental work consisted of (1) evaluating the melting behavior and characteristics, (2) measurement of the viscosity and electrical conductivity of promising melts over their melting range, (3) determining the chemical durability by the PCT and VHT methods of both glassy and partially crystallized iron phosphate wasteforms, (4) determining the solubility limit for chrome oxide in selected iron phosphate melts, (5) examining the feasibility of melting iron phosphate glasses by Cold Crucible Induction melting (CCIM), Hot Crucible Induction Melting (HCIM), and Microwave Melting, (6) and measuring the corrosion of Inconel 690 and 693, potential electrode materials, in an iron phosphate melt. In the past year, the results of the above experimental work have been described in eight technical papers and reports that have been submitted for publication.","Iron Phosphate Glasses: An Alernative for Vitrifying Certain Nuclear Wastes. (Report for June 16, 2002 to June 15, 2003) Abs: Annual rept. red by Department of Energy, Washington, DC. the past year, iron phosphate glasses containing the following three types of nuclear waste, as recommended by the Tank Focus Area (TFA) group, have been investigated. (1) a high sodium/sulfate Hanford Low-Activity Waste (LAW) (2) a High Chrome Waste (HCW) at Hanford, and (3) a Sodium Bearing Waste (SBW) at Idaho National Engineering and Environmental Laboratory (INEEL) Over three hundred trial melts, ranging in size from 50 g to more than 10 kg, have been evaluated. The experimental work consisted of (1) evaluating the melting behavior and characteristics, (2) measurement of the viscosity and electrical conductivity of promising melts over their melting range, (3) determining the chemical durability by the PCT and VHT methods of both glassy and partially crystallized iron phosphate wasteforms, (4) determining the solubility limit for chrome oxide in selected iron phosphate melts, (5) examining the feasibility of melting iron phosphate glasses by Cold Crucible Induction melting (CCIM), Hot Crucible Induction Melting (HCIM), and Microwave Melting, (6) and measuring the corrosion of Inconel 690 and 693, potential electrode materials, in an iron phosphate melt. In the past year, the results of the above experimental work have been described in eight technical papers and reports that have been submitted for publication."
1510115,Arrington 2000,Processing of High Level Waste: Spectroscopic Characterization of Redox Reactions in Supercritical Water. Final Report,"Current efforts are focused on the oxidative dissolution of chromium compounds found in Hanford tank waste sludge. Samples of chromium oxides and hydroxides with varying degrees of hydration are being characterized using Raman, FTIR, and XPS spectroscopic techniques. Kinetics of oxidation reactions at subcritical and supercritical temperatures are being followed by Raman spectroscopy using a high temperature stainless steel cell with diamond windows. In these reactions both hydrogen peroxide and nitrate anions are used as the oxidizing species with Cr(III) compounds and organic compounds as reducing agents.","Processing of High Level Waste: Spectroscopic Characterization of Redox Reactions in Supercritical Water. Final Report Abs: Current efforts are focused on the oxidative dissolution of chromium compounds found in Hanford tank waste sludge. Samples of chromium oxides and hydroxides with varying degrees of hydration are being characterized using Raman, FTIR, and XPS spectroscopic techniques. Kinetics of oxidation reactions at subcritical and supercritical temperatures are being followed by Raman spectroscopy using a high temperature stainless steel cell with diamond windows. In these reactions both hydrogen peroxide and nitrate anions are used as the oxidizing species with Cr(III) compounds and organic compounds as reducing agents."
1510114,Patton et al. 2001,Chromium Toxicity Test for Fall Chinook Salmon (Oncorhynchus tshawytscha) Using Hanford Site Groundwater: Onsite Early Life-Stage Toxicity Evaluation,"The objective of this study was to evaluate site-specific effects for early life-stage (eyed eggs to free swimming juveniles) fall chinook salmon that might be exposed to hexavalent chromium from Hanford groundwater sources. Our exposure conditions included hexavalent chromium obtained from Hanford groundwater wells near the Columbia River, Columbia River water as the diluent, and locally adapted populations of fall chinook salmon. This report describes both a 96-hr pretest using rainbow trout eggs and an early life-stage test beginning with chinook salmon eggs.","Chromium Toxicity Test for Fall Chinook Salmon (Oncorhynchus tshawytscha) Using Hanford Site Groundwater: Onsite Early Life-Stage Toxicity Evaluation Abs: The objective of this study was to evaluate site-specific effects for early life-stage (eyed eggs to free swimming juveniles) fall chinook salmon that might be exposed to hexavalent chromium from Hanford groundwater sources. Our exposure conditions included hexavalent chromium obtained from Hanford groundwater wells near the Columbia River, Columbia River water as the diluent, and locally adapted populations of fall chinook salmon. This report describes both a 96-hr pretest using rainbow trout eggs and an early life-stage test beginning with chinook salmon eggs."
1510113,Thornton et al. 2001,Characterization Activities Conducted at the 183-DR Site in Support of an In Situ Gaseous Reduction Demonstration,"In Situ Gaseous Reduction (ISGR) is a technology developed by DOE for the remediation of soil waste sites contaminated with hexavalent chromium. This document presents information associated with characterization activities conducted at the 183-DR site at Hanford, which is associated with a significant groundwater contaminant plume and was formerly a water treatment facility that utilized chromate as a corrosion inhibitor. Geotechnical and chemical data were collected during the excavation of trenches and the drilling of two vadose zone boreholes to support a possible ISGR demonstration at 183-DR. Although elevated total chromium and trace levels of hexavalent chromium were identified from one of the trenches and one of the boreholes, it appears that the boreholes missed the vadose zone contaminant source responsible for the chromium groundwater plume located downgradient of the 183-DR site. Recommendations are provided, however, for future work at 183-DR that may serve to identify the source for the groundwater plume and possibly provide an opportunity for an ISGR demonstration.","Characterization Activities Conducted at the 183-DR Site in Support of an In Situ Gaseous Reduction Demonstration Abs: In Situ Gaseous Reduction (ISGR) is a technology developed by DOE for the remediation of soil waste sites contaminated with hexavalent chromium. This document presents information associated with characterization activities conducted at the 183-DR site at Hanford, which is associated with a significant groundwater contaminant plume and was formerly a water treatment facility that utilized chromate as a corrosion inhibitor. Geotechnical and chemical data were collected during the excavation of trenches and the drilling of two vadose zone boreholes to support a possible ISGR demonstration at 183-DR. Although elevated total chromium and trace levels of hexavalent chromium were identified from one of the trenches and one of the boreholes, it appears that the boreholes missed the vadose zone contaminant source responsible for the chromium groundwater plume located downgradient of the 183-DR site. Recommendations are provided, however, for future work at 183-DR that may serve to identify the source for the groundwater plume and possibly provide an opportunity for an ISGR demonstration."
1510112,Thornton et al. 2000,Identification of a Hanford Waste Site for Initial Deployment of the In Situ Gaseous Reduction Approach,In Situ Gaseous Reduction is a technology currently being developed by DOE for the remediation of soil waste sites contaminated with hexavalent chromium. This document presents the results of recent characterization activities undertaken at several of the soil waste sites at Hanford that contain significant levels of hexavalent chromium contamination. The objective of this study is to select a site for initial deployment of the technology at the Hanford Site.,Identification of a Hanford Waste Site for Initial Deployment of the In Situ Gaseous Reduction Approach Abs: In Situ Gaseous Reduction is a technology currently being developed by DOE for the remediation of soil waste sites contaminated with hexavalent chromium. This document presents the results of recent characterization activities undertaken at several of the soil waste sites at Hanford that contain significant levels of hexavalent chromium contamination. The objective of this study is to select a site for initial deployment of the technology at the Hanford Site.
1510111,Thornton et al. 2000,Description of Work for Drilling at the 183-DR Site in Support of the In situ Gaseous Reduction Test,"This document describes field activities associated with installation of boreholes to verify the presence of hexavalent chromium in the vadose zone at the former location of the 183-DR facility, a water treatment plant, in the 100 D/DR Area of the U.S. Department of Energy (DOE) Hanford Site, Richland, Washington. If the zone of contamination is identified, treatment by injection of a reactive gas (In Situ Gaseous Reduction or ISGR) has been proposed. The ISGR approach is expected to have a significant effect on local groundwater by immobilizing chromium in the vadose zone. Thus, sampling and analysis of vadose zone samples to support data collection needs for the 183-DR ISGR demonstration will be completed as outlined in this drilling description of work. A draft treatability test plan has also been prepared that describes technical activities and requirements associated with the gas treatment demonstration.","Description of Work for Drilling at the 183-DR Site in Support of the In situ Gaseous Reduction Test Abs: This document describes field activities associated with installation of boreholes to verify the presence of hexavalent chromium in the vadose zone at the former location of the 183-DR facility, a water treatment plant, in the 100 D/DR Area of the U.S. Department of Energy (DOE) Hanford Site, Richland, Washington. If the zone of contamination is identified, treatment by injection of a reactive gas (In Situ Gaseous Reduction or ISGR) has been proposed. The ISGR approach is expected to have a significant effect on local groundwater by immobilizing chromium in the vadose zone. Thus, sampling and analysis of vadose zone samples to support data collection needs for the 183-DR ISGR demonstration will be completed as outlined in this drilling description of work. A draft treatability test plan has also been prepared that describes technical activities and requirements associated with the gas treatment demonstration."
1510110,Knepp 1997,In situ redox manipulation treatability test: waste management plan,This Waste Management Plan provides guidance for the management of waste generated from groundwater well installations in the 100-HR-3 Operable Unit. The well installations are necessary to implement the In Situ Redox Manipulation Treatability Test to determine methods for in situ remedial efforts to prevent discharge of hexavalent chromium at levels above those considered protective of aquatic life in the Columbia River and riverbed sediments,In situ redox manipulation treatability test: waste management plan Abs: This Waste Management Plan provides guidance for the management of waste generated from groundwater well installations in the 100-HR-3 Operable Unit. The well installations are necessary to implement the In Situ Redox Manipulation Treatability Test to determine methods for in situ remedial efforts to prevent discharge of hexavalent chromium at levels above those considered protective of aquatic life in the Columbia River and riverbed sediments
1510109,Chou and  Johnson 1999,Rcra assessment plan for single-shell tank waste management area s-sx at the hanford site,"A groundwater quality assessment plan was prepared for waste management area S-SX at the Hanford Site. Groundwater monitoring is conducted at this facility in accordance with Title 40, Code of Federal Regulation (CFR) Part 265, Subpart F (and by reference of Washington Administrative Code (WAC) 173-303-400(3)). The facility was placed in assessment groundwater monitoring program status after elevated waste constituents and indicator parameter measurements (i.e., chromium, technetium-99 and specific conductance) in downgradient monitoring wells were observed and confirmed. A first determination, as allowed under 40 CFR 265.93(d), provides the owner/operator of a facility an opportunity to demonstrate that the regulated unit is not the source of groundwater contamination. Based on results of the first determination it was concluded that multiple source locations in the waste management area could account for observed spatial and temporal groundwater contamination patterns. Consequently, a continued investigation is required. This plan, developed using the data quality objectives process, is intended to comply with the continued investigation requirement. Accordingly, the primary purpose of the present plan is to determine the rate and extent of dangerous waste (hexavalent chromium and nitrate) and radioactive constituents (e.g., technetium-99) in groundwater and to determine their concentrations in groundwater beneath waste management area S-SX. Comments and concerns expressed by the Washington State Department of Ecology on the initial waste management area S-SX assessment report were addressed in the descriptive narrative of this plan as well as in the planned activities. Comment disposition is documented in a separate addendum to this plan.","Rcra assessment plan for single-shell tank waste management area s-sx at the hanford site Abs: A groundwater quality assessment plan was prepared for waste management area S-SX at the Hanford Site. Groundwater monitoring is conducted at this facility in accordance with Title 40, Code of Federal Regulation (CFR) Part 265, Subpart F (and by reference of Washington Administrative Code (WAC) 173-303-400(3)). The facility was placed in assessment groundwater monitoring program status after elevated waste constituents and indicator parameter measurements (i.e., chromium, technetium-99 and specific conductance) in downgradient monitoring wells were observed and confirmed. A first determination, as allowed under 40 CFR 265.93(d), provides the owner/operator of a facility an opportunity to demonstrate that the regulated unit is not the source of groundwater contamination. Based on results of the first determination it was concluded that multiple source locations in the waste management area could account for observed spatial and temporal groundwater contamination patterns. Consequently, a continued investigation is required. This plan, developed using the data quality objectives process, is intended to comply with the continued investigation requirement. Accordingly, the primary purpose of the present plan is to determine the rate and extent of dangerous waste (hexavalent chromium and nitrate) and radioactive constituents (e.g., technetium-99) in groundwater and to determine their concentrations in groundwater beneath waste management area S-SX. Comments and concerns expressed by the Washington State Department of Ecology on the initial waste management area S-SX assessment report were addressed in the descriptive narrative of this plan as well as in the planned activities. Comment disposition is documented in a separate addendum to this plan."
1510107,Swanson et al. 1998,"Fiscal Year 1997 Annual Report for the 100-NR-2, 200-UP-1, and 200-ZP-1 Pump and Treat Operations and Operable Units","Sponsored by Department of Energy, Washington, DC. vironmental Restoration Contractor (ERC), Bechtel Hanford, Inc., conducts groundwater remediation activities across the Hanford Site for the U.S. Department of Energy. Operable units, as defined under CERCLA, have been established to address groundwater contamination issues in various areas of the Site. Groundwater within these operable units has been contaminated by a variety of chemical and radiological constituents associated with past-practices liquid effluent disposal, as well as accidental leaks and spills. The ERC is currently operating three pump-and-treat systems in the 100 Area: Strontium-90 is being addressed in the 100-NR-2 Operable Unit, while hexavalent chromium is being addressed in the 100-KR-4 and 100-HR-3 Operable Units. In the 200 Area, technetium-99, uranium, carbon tetrachloride, and nitrate are being addressed in the 200-UP-1 Operable Unit, while carbon tetrachloride, trichloroethene, and chloroform are being addressed in the 200-ZP-1 Operable Unit.","Fiscal Year 1997 Annual Report for the 100-NR-2, 200-UP-1, and 200-ZP-1 Pump and Treat Operations and Operable Units Abs: Sponsored by Department of Energy, Washington, DC. vironmental Restoration Contractor (ERC), Bechtel Hanford, Inc., conducts groundwater remediation activities across the Hanford Site for the U.S. Department of Energy. Operable units, as defined under CERCLA, have been established to address groundwater contamination issues in various areas of the Site. Groundwater within these operable units has been contaminated by a variety of chemical and radiological constituents associated with past-practices liquid effluent disposal, as well as accidental leaks and spills. The ERC is currently operating three pump-and-treat systems in the 100 Area: Strontium-90 is being addressed in the 100-NR-2 Operable Unit, while hexavalent chromium is being addressed in the 100-KR-4 and 100-HR-3 Operable Units. In the 200 Area, technetium-99, uranium, carbon tetrachloride, and nitrate are being addressed in the 200-UP-1 Operable Unit, while carbon tetrachloride, trichloroethene, and chloroform are being addressed in the 200-ZP-1 Operable Unit."
1510106,Connelly 1997,Chromium Plume West of the 100-D/DR Reactors Data Supplement,"Sponsored by Department of Energy, Washington, DC. the primary focuses of the Hanford Environmental Restoration program has been the protection of human health and the environment. One environmental threat is the chromium contamination in groundwater that is migrating to the Columbia River. In an effort to better characterize the nature and extent of groundwater impacting the Columbia River along the 100 Area shoreline, river substrate pore water samples were taken in November 1995 and analyzed for hexavalent chromium and other relevant parameters that could be screened in the field. One of the most surprising discoveries from this effort was the relatively high levels (approximately 600 Tg/L) in an unexpected location west of and upstream from the 100-D/DR Reactors. This area became known as the 'D-Area Hot Spot.'","Chromium Plume West of the 100-D/DR Reactors Data Supplement Abs: Sponsored by Department of Energy, Washington, DC. the primary focuses of the Hanford Environmental Restoration program has been the protection of human health and the environment. One environmental threat is the chromium contamination in groundwater that is migrating to the Columbia River. In an effort to better characterize the nature and extent of groundwater impacting the Columbia River along the 100 Area shoreline, river substrate pore water samples were taken in November 1995 and analyzed for hexavalent chromium and other relevant parameters that could be screened in the field. One of the most surprising discoveries from this effort was the relatively high levels (approximately 600 Tg/L) in an unexpected location west of and upstream from the 100-D/DR Reactors. This area became known as the 'D-Area Hot Spot.'"
1510105,Lindgren et al. 1998,Electrokinetic demonstration at the unlined chromic acid pit,"Sponsored by Department of Energy, Washington, DC. metal contaminated soils are a common problem at Department of Energy (DOE)-operated sites and privately owned facilities throughout the nation. One emerging technology which can remove heavy metals from soil in situ is electrokinetics. To conduct electrokinetic (EK) remediation, electrodes are implanted into the ground, and a direct current is imposed between the electrodes. Metal ions dissolved in the soil pore water migrate towards an electrode where they can be removed. The electrokinetic program at Sandia National Laboratories (SNL) has been focusing on electrokinetic remediation for unsaturated soils. A patent was awarded for an electrokinetic electrode system designed at SNL for applications to unsaturated soils. Current research described in this report details an electrokinetic remediation field demonstration of a chromium plume that resides in unsaturated soil beneath the SNL Chemical Waste Landfill (CWL). This report describes the processes, site investigation, operation and monitoring equipment, testing procedures, and extraction results of the electrokinetic demonstration. This demonstration successfully removed chromium contamination in the form of chromium(VI) from unsaturated soil at the field scale. After 2700 hours of operation, 600 grams of Cr(VI) was extracted from the soil beneath the SNL CWL in a series of thirteen tests. The contaminant was removed from soil which has moisture contents ranging from 2 to 12 weight percent. This demonstration was the first EK field trial to successfully remove contaminant ions from and soil at the field scale. Although the new patented electrode system was successful in removing an anionic contaminant (i.e., chromate) from unsaturated sandy soil, the electrode system was a prototype and has not been specifically engineered for commercialization. A redesign of the electrode system as indicated by the results of this research is suggested for future EK field trials.","Electrokinetic demonstration at the unlined chromic acid pit Abs: Sponsored by Department of Energy, Washington, DC. metal contaminated soils are a common problem at Department of Energy (DOE)-operated sites and privately owned facilities throughout the nation. One emerging technology which can remove heavy metals from soil in situ is electrokinetics. To conduct electrokinetic (EK) remediation, electrodes are implanted into the ground, and a direct current is imposed between the electrodes. Metal ions dissolved in the soil pore water migrate towards an electrode where they can be removed. The electrokinetic program at Sandia National Laboratories (SNL) has been focusing on electrokinetic remediation for unsaturated soils. A patent was awarded for an electrokinetic electrode system designed at SNL for applications to unsaturated soils. Current research described in this report details an electrokinetic remediation field demonstration of a chromium plume that resides in unsaturated soil beneath the SNL Chemical Waste Landfill (CWL). This report describes the processes, site investigation, operation and monitoring equipment, testing procedures, and extraction results of the electrokinetic demonstration. This demonstration successfully removed chromium contamination in the form of chromium(VI) from unsaturated soil at the field scale. After 2700 hours of operation, 600 grams of Cr(VI) was extracted from the soil beneath the SNL CWL in a series of thirteen tests. The contaminant was removed from soil which has moisture contents ranging from 2 to 12 weight percent. This demonstration was the first EK field trial to successfully remove contaminant ions from and soil at the field scale. Although the new patented electrode system was successful in removing an anionic contaminant (i.e., chromate) from unsaturated sandy soil, the electrode system was a prototype and has not been specifically engineered for commercialization. A redesign of the electrode system as indicated by the results of this research is suggested for future EK field trials."
1510104,Stjohn 1997,"Site specific health and safety plan, 100-HR-3 pump and treat. Revision 2","The 100-HR-3 Pump and Treat system is a groundwater remedial action to remove Hexavalent Chromium (Cr+6) from the groundwater underlying the 100-HR-3 Operable Unit. This plan covers operation, maintenance, repairs, resin exchange and equipment removal/installation. The 100-HR-3 Operable Unit addresses groundwater underlying the 100-D Area. The primary groundwater contaminant is Chromium +6. The chromium contamination resulted from the use of sodium dichromate during past reactor operations. Sodium dichromate was used to treat reactor coolant water during reactor operations. The purpose of this Pump and Treat system is to pump contaminated groundwater through above ground ion exchange resin and then return treated water to aquifer. Chromium levels extracted from the wells are anticipated to range in the low parts per billion ((approximately)50 ppb) which is the drinking water limit for Cr+6.","Site specific health and safety plan, 100-HR-3 pump and treat. Revision 2 Abs: The 100-HR-3 Pump and Treat system is a groundwater remedial action to remove Hexavalent Chromium (Cr+6) from the groundwater underlying the 100-HR-3 Operable Unit. This plan covers operation, maintenance, repairs, resin exchange and equipment removal/installation. The 100-HR-3 Operable Unit addresses groundwater underlying the 100-D Area. The primary groundwater contaminant is Chromium +6. The chromium contamination resulted from the use of sodium dichromate during past reactor operations. Sodium dichromate was used to treat reactor coolant water during reactor operations. The purpose of this Pump and Treat system is to pump contaminated groundwater through above ground ion exchange resin and then return treated water to aquifer. Chromium levels extracted from the wells are anticipated to range in the low parts per billion ((approximately)50 ppb) which is the drinking water limit for Cr+6."
1510103,Moody and  Conca 1996,Permeable barrier materials for strontium immobilization: Unsaturated flow apparatus determination of hydraulic conductivity -- Column sorption experiments,"Sponsored by Department of Energy, Washington, DC. ed materials were tested to emulate a permeable barrier and to examine the (1) capture efficiency of these materials relating to the immobilization of strontium-90 and hexavalent chromium (Cr(sup 6+)) in Hanford Site groundwater; and (2) hydraulic conductivity of the barrier material relative to the surrounding area. The emplacement method investigated was a permeable reactive barrier to treat contaminated groundwater as it passes through the barrier. The hydraulic conductivity function was measured for each material, and retardation column experiments were performed for each material. Measurements determining the hydraulic conductivity at unsaturated through saturated water content were executed using the Unsaturated Flow Apparatus.","Permeable barrier materials for strontium immobilization: Unsaturated flow apparatus determination of hydraulic conductivity -- Column sorption experiments Abs: Sponsored by Department of Energy, Washington, DC. ed materials were tested to emulate a permeable barrier and to examine the (1) capture efficiency of these materials relating to the immobilization of strontium-90 and hexavalent chromium (Cr(sup 6+)) in Hanford Site groundwater; and (2) hydraulic conductivity of the barrier material relative to the surrounding area. The emplacement method investigated was a permeable reactive barrier to treat contaminated groundwater as it passes through the barrier. The hydraulic conductivity function was measured for each material, and retardation column experiments were performed for each material. Measurements determining the hydraulic conductivity at unsaturated through saturated water content were executed using the Unsaturated Flow Apparatus."
1510102,Hope 1996,1907-DR Process Sewer Outfall site soil characterization,"Sponsored by Department of Energy, Washington, DC. jective of this characterization effort was to determine if the soil downgradient of the former outfall is contaminated with hexavalent chromium at levels above those protective of human health and the environment. This report summarizes the results of soil sampling for hexavalent chromium conducted at the former 1907-DR Process Sewer Outfall structure (located on the Hanford Site in Richland, Washington). Historical investigations of past operational practices suggest that soil at the site of the former outfall structure may be a source of chromium contamination offshore from the outfall site.","1907-DR Process Sewer Outfall site soil characterization Abs: Sponsored by Department of Energy, Washington, DC. jective of this characterization effort was to determine if the soil downgradient of the former outfall is contaminated with hexavalent chromium at levels above those protective of human health and the environment. This report summarizes the results of soil sampling for hexavalent chromium conducted at the former 1907-DR Process Sewer Outfall structure (located on the Hanford Site in Richland, Washington). Historical investigations of past operational practices suggest that soil at the site of the former outfall structure may be a source of chromium contamination offshore from the outfall site."
1510101,Hope and  Peterson 1996,"Chromium in river substrate pore water and adjacent groundwater: 100-D/DR area, Hanford site, Washington","Sponsored by Department of Energy, Washington, DC. eport describes the field investigation of groundwater discharging from the 100-D/DR Reactor Area into the Hanford Reach of the Columbia River located in Richland, Washington. This section of the Reach is used by fall chinook salmon as spawning habitat. The field investigation focused on hexavalent chromium in river substrate pore water, river water, riverbank seepage, and the Hanford Site aquifer at the shoreline. These data are used to establish a baseline for chromium concentrations in river substrate pore water and in the aquifer. This baseline will help assess the potential for exposure of ecological receptors to contaminated groundwater discharges and support groundwater remediation services. This groundwater is contaminated with hexavalent chromium at concentrations that exceed the U.S. Environmental Protection Agency's chronic ambient water quality criterion.","Chromium in river substrate pore water and adjacent groundwater: 100-D/DR area, Hanford site, Washington Abs: Sponsored by Department of Energy, Washington, DC. eport describes the field investigation of groundwater discharging from the 100-D/DR Reactor Area into the Hanford Reach of the Columbia River located in Richland, Washington. This section of the Reach is used by fall chinook salmon as spawning habitat. The field investigation focused on hexavalent chromium in river substrate pore water, river water, riverbank seepage, and the Hanford Site aquifer at the shoreline. These data are used to establish a baseline for chromium concentrations in river substrate pore water and in the aquifer. This baseline will help assess the potential for exposure of ecological receptors to contaminated groundwater discharges and support groundwater remediation services. This groundwater is contaminated with hexavalent chromium at concentrations that exceed the U.S. Environmental Protection Agency's chronic ambient water quality criterion."
1510100,Lindgren and  Mattson 1997,Electrokinetic demonstration at Sandia National Laboratories: Use of transference numbers for site characterization and process evaluation,"Waste Management '97, Tucson, AZ (United States), 2-7 Mar 1997. Sponsored by Department of Energy, Washington, DC. okinetic remediation is generally an in situ method using direct current electric potentials to move ionic contaminants and/or water to collection electrodes. The method has been extensively studied for application in saturated clayey soils. Over the past few years, an electrokinetic extraction method specific for sandy, unsaturated soils has been developed and patented by Sandia National Laboratories. A RCRA RD&amp;D permitted demonstration of this technology for the in situ removal of chromate contamination from unsaturated soils in a former chromic acid disposal pit was operated during the summer and fall of 1996. This large scale field test represents the first use of electrokinetics for the removal of heavy metal contamination from unsaturated soils in the United States and is part of the US EPA Superfund Innovative Technology Evaluation (SITE) Program. Guidelines for characterizing a site for electrokinetic remediation are lacking, especially for applications in unsaturated soil. The transference number of an ion is the fraction of the current carried by that ion in an electric field and represents the best measure of contaminant removal efficiency in most electrokinetic remediation processes. In this paper we compare the transference number of chromate initially present in the contaminated unsaturated soil, with the transference number in the electrokinetic process effluent to demonstrate the utility of evaluating this parameter.","Electrokinetic demonstration at Sandia National Laboratories: Use of transference numbers for site characterization and process evaluation Abs: Waste Management '97, Tucson, AZ (United States), 2-7 Mar 1997. Sponsored by Department of Energy, Washington, DC. okinetic remediation is generally an in situ method using direct current electric potentials to move ionic contaminants and/or water to collection electrodes. The method has been extensively studied for application in saturated clayey soils. Over the past few years, an electrokinetic extraction method specific for sandy, unsaturated soils has been developed and patented by Sandia National Laboratories. A RCRA RD&amp;D permitted demonstration of this technology for the in situ removal of chromate contamination from unsaturated soils in a former chromic acid disposal pit was operated during the summer and fall of 1996. This large scale field test represents the first use of electrokinetics for the removal of heavy metal contamination from unsaturated soils in the United States and is part of the US EPA Superfund Innovative Technology Evaluation (SITE) Program. Guidelines for characterizing a site for electrokinetic remediation are lacking, especially for applications in unsaturated soil. The transference number of an ion is the fraction of the current carried by that ion in an electric field and represents the best measure of contaminant removal efficiency in most electrokinetic remediation processes. In this paper we compare the transference number of chromate initially present in the contaminated unsaturated soil, with the transference number in the electrokinetic process effluent to demonstrate the utility of evaluating this parameter."
1510099,Hong et al. 1995,Studies on treatment and manufacturing of industrial materials,"Korean. e technical development on utilization of domestic unused resources, the study on the production and the process of industrial raw materials was carried out. This study is divided into five articles and their main results are summarized as follows. 1. The utilization of chromic oxide wastes: This study was carried out to develop the optimum process for recovering precious and valuable metals from chrome oxide wastes. The following subjects such as, feasibility on the recovery of precious and valuable metals, recovery rate of precious and valuable metals, purification of extracted precious and valuable metals, and environmental aspects of recovery process, were investigated. 2. The production of ultramarine from nonmetal minerals: The aims were the determination of the optimum conditions of calcination of raw materials and the investigation of the synthesis mechanism of ultramarine green and blue. 3. The synthesis in fine calcium carbonate powder and it's characteristics: The transformation process of amorphous CaCO(sub 3) obtained from the reaction between aqueous solution of Ca(OH)(sub 2) and CO(sub 2) at 10, 15, 20 and 25 degree was traced continuously by measuring the electrical conductivity of the reaction solution and the influences of reaction temperature, electrical conductivity value of the reaction solution on the products after transformation were examined by x-ray powder diffraction and electron microscopy. 4. Mineral processing technology for abrasive minerals: Buyeo Materials in Buyeogun, Choongnam province is a company producing feldspar concentrate, but does not yet utilize the garnet as abrasive material and other useful heavy minerals wasted out from the process of feldspar ore. This aimed to develop technology and process for the recovery of garnet concentrate. 5. Synthesis of nitride material by plasma method: DC plasma torch which is a non-transferred type was constructed and silicon nitride powders were produced. (Abstract Truncated)","Studies on treatment and manufacturing of industrial materials Abs: Korean. e technical development on utilization of domestic unused resources, the study on the production and the process of industrial raw materials was carried out. This study is divided into five articles and their main results are summarized as follows. 1. The utilization of chromic oxide wastes: This study was carried out to develop the optimum process for recovering precious and valuable metals from chrome oxide wastes. The following subjects such as, feasibility on the recovery of precious and valuable metals, recovery rate of precious and valuable metals, purification of extracted precious and valuable metals, and environmental aspects of recovery process, were investigated. 2. The production of ultramarine from nonmetal minerals: The aims were the determination of the optimum conditions of calcination of raw materials and the investigation of the synthesis mechanism of ultramarine green and blue. 3. The synthesis in fine calcium carbonate powder and it's characteristics: The transformation process of amorphous CaCO(sub 3) obtained from the reaction between aqueous solution of Ca(OH)(sub 2) and CO(sub 2) at 10, 15, 20 and 25 degree was traced continuously by measuring the electrical conductivity of the reaction solution and the influences of reaction temperature, electrical conductivity value of the reaction solution on the products after transformation were examined by x-ray powder diffraction and electron microscopy. 4. Mineral processing technology for abrasive minerals: Buyeo Materials in Buyeogun, Choongnam province is a company producing feldspar concentrate, but does not yet utilize the garnet as abrasive material and other useful heavy minerals wasted out from the process of feldspar ore. This aimed to develop technology and process for the recovery of garnet concentrate. 5. Synthesis of nitride material by plasma method: DC plasma torch which is a non-transferred type was constructed and silicon nitride powders were produced. (Abstract Truncated)"
1510098,Mathur et al. 1995,Partitioning and recovery of neptunium from high level waste streams of PUREX origin using 30% TBP,"sup 237 Np is one of the longest-lived nuclides among the actinides present in the high level waste solutions of reprocessing origin. Its separation, recovery and transmutation can reduce the problem of long term storage of the vitrified waste to a great extent. With this objective, the present work was initiated to study the extraction of neptunium into TBP under the conditions relevant to high level waste, along with uranium and plutonium by oxidising it to hexavalent state using potassium dichromate and subsequently recovering it by selective stripping. Three types of simulated HLW solutions namely sulphate bearing (SB), with an acidity of (approx) 0.3 M and non-sulphate wastes originating from the reprocessing of fuels from pressurised heavy water reactor (PHWR) and fast breeder reactor (FBR) with acidities of 3.0 M HNO(sub 3) were employed in these studies. The extraction of U(VI), Np(VI) and Pu(VI) was very high for PHWR- and FBR-HLW solutions, whereas for the SB-HLW solution, these values were less but reasonably high. Quantitative recovery of neptunium and plutonium was achieved using a stripping solution containing 0.1 M H(sub 2)O(sub 2) and 0.01 M ascorbic acid at an acidity of 2.0 M. Since, cerium present in the waste solutions is expected to undergo oxidation in presence of K(sub 2)Cr(sub 2)O(sub 7), its extraction behaviour was also studied under similar conditions. Based on the results, a scheme was formulated for the recovery of neptunium along with plutonium and was successfully applied to actual high level waste solution originating from the reprocessing of research reactor fuels. (author). 19 refs., 2 figs., 17 tabs. (Atomindex citation 27:030808)","Partitioning and recovery of neptunium from high level waste streams of PUREX origin using 30% TBP Abs: sup 237 Np is one of the longest-lived nuclides among the actinides present in the high level waste solutions of reprocessing origin. Its separation, recovery and transmutation can reduce the problem of long term storage of the vitrified waste to a great extent. With this objective, the present work was initiated to study the extraction of neptunium into TBP under the conditions relevant to high level waste, along with uranium and plutonium by oxidising it to hexavalent state using potassium dichromate and subsequently recovering it by selective stripping. Three types of simulated HLW solutions namely sulphate bearing (SB), with an acidity of (approx) 0.3 M and non-sulphate wastes originating from the reprocessing of fuels from pressurised heavy water reactor (PHWR) and fast breeder reactor (FBR) with acidities of 3.0 M HNO(sub 3) were employed in these studies. The extraction of U(VI), Np(VI) and Pu(VI) was very high for PHWR- and FBR-HLW solutions, whereas for the SB-HLW solution, these values were less but reasonably high. Quantitative recovery of neptunium and plutonium was achieved using a stripping solution containing 0.1 M H(sub 2)O(sub 2) and 0.01 M ascorbic acid at an acidity of 2.0 M. Since, cerium present in the waste solutions is expected to undergo oxidation in presence of K(sub 2)Cr(sub 2)O(sub 7), its extraction behaviour was also studied under similar conditions. Based on the results, a scheme was formulated for the recovery of neptunium along with plutonium and was successfully applied to actual high level waste solution originating from the reprocessing of research reactor fuels. (author). 19 refs., 2 figs., 17 tabs. (Atomindex citation 27:030808)"
1510096,Yang et al. 1995,"Superior catalysts for selective catalytic reduction of nitric oxide. Final technical report, October 1, 1993--September 30, 1995","Progress rept. red by Department of Energy, Washington, DC. st advanced and proven technology for NO(sub x) control for stationary sources is Selective Catalytic Reduction (SCR). In SCR, NO(sub x) is reduced by NH(sub 3) to N(sub 2) and H(sub 2)O. The commercial catalysts are based on V(sub 2)O(sub 5)/TiO(sub 2), and the vanadium-based catalysts are patented by the Japanese (Mitsubishi). However, there are three main advantages for the vanadium-based SCR catalyst: (a) a tendency to be poisoned in the flue gas; (b) oxidation of SO(sub 2) to SO(sub 3) by V(sub 2)O(sub 5), this is a particularly severe problem due to the higher sulfur content of American coals compared with coals used in Japan (from Australia) and in Europe; (c) environmental problems involved in the disposal of the spent catalyst (due to the toxicity of vanadium). In order to overcome these problems, in addition to the undesirable dominance by the Japanese patent position, the authors have studied in this project a new type of catalyst for the SCR reaction; namely, pillared clays, which have adjustable, unique structures and acidity. Three types of catalysts were developed and tested for this reaction, i.e. Fe(sub 2)O(sub 3)-pillared clays, delaminated Fe(sub 2)O(sub 3)-pillared clays, and ion-exchanged pillared clays. The project was divided into sixteen tasks, and will be reported as such.","Superior catalysts for selective catalytic reduction of nitric oxide. Final technical report, October 1, 1993--September 30, 1995 Abs: Progress rept. red by Department of Energy, Washington, DC. st advanced and proven technology for NO(sub x) control for stationary sources is Selective Catalytic Reduction (SCR). In SCR, NO(sub x) is reduced by NH(sub 3) to N(sub 2) and H(sub 2)O. The commercial catalysts are based on V(sub 2)O(sub 5)/TiO(sub 2), and the vanadium-based catalysts are patented by the Japanese (Mitsubishi). However, there are three main advantages for the vanadium-based SCR catalyst: (a) a tendency to be poisoned in the flue gas; (b) oxidation of SO(sub 2) to SO(sub 3) by V(sub 2)O(sub 5), this is a particularly severe problem due to the higher sulfur content of American coals compared with coals used in Japan (from Australia) and in Europe; (c) environmental problems involved in the disposal of the spent catalyst (due to the toxicity of vanadium). In order to overcome these problems, in addition to the undesirable dominance by the Japanese patent position, the authors have studied in this project a new type of catalyst for the SCR reaction; namely, pillared clays, which have adjustable, unique structures and acidity. Three types of catalysts were developed and tested for this reaction, i.e. Fe(sub 2)O(sub 3)-pillared clays, delaminated Fe(sub 2)O(sub 3)-pillared clays, and ion-exchanged pillared clays. The project was divided into sixteen tasks, and will be reported as such."
1510095,Vienna and  Hrma 1996,Glass formulation for phase 1 high-level waste vitrification,"Sponsored by Department of Energy, Washington, DC. rpose of this study is to provide potential glass formulations for prospective Phase 1 High-Level Waste (HLW) vitrification at Hanford. The results reported here will be used to aid in developing a Phase 1 HLW vitrification request for proposal (RFP) and facilitate the evaluation of ensuing proposals. The following factors were considered in the glass formulation effort: impact on total glass volume of requiring the vendor to process each of the tank compositions independently versus as a blend; effects of imposing typical values of B(sub 2)O(sub 3) content and waste loading in HLW borosilicate glasses as restrictions on the vendors (according to WAPS 1995, the typical values are 5--10 wt% B(sub 2)O(sub 3) and 20--40 wt% waste oxide loading); impacts of restricting the processing temperature to 1,150 C on eventual glass volume; and effects of caustic washing on any of the selected tank wastes relative to glass volume.","Glass formulation for phase 1 high-level waste vitrification Abs: Sponsored by Department of Energy, Washington, DC. rpose of this study is to provide potential glass formulations for prospective Phase 1 High-Level Waste (HLW) vitrification at Hanford. The results reported here will be used to aid in developing a Phase 1 HLW vitrification request for proposal (RFP) and facilitate the evaluation of ensuing proposals. The following factors were considered in the glass formulation effort: impact on total glass volume of requiring the vendor to process each of the tank compositions independently versus as a blend; effects of imposing typical values of B(sub 2)O(sub 3) content and waste loading in HLW borosilicate glasses as restrictions on the vendors (according to WAPS 1995, the typical values are 5--10 wt% B(sub 2)O(sub 3) and 20--40 wt% waste oxide loading); impacts of restricting the processing temperature to 1,150 C on eventual glass volume; and effects of caustic washing on any of the selected tank wastes relative to glass volume."
1510094,Vojtech et al. 1996,Effect of chromium oxide on the properties of simulated nuclear waste glasses,"Sponsored by Department of Energy, Washington, DC. y of the effect of chromium on the properties of selected glasses was performed in the frame of a Contract between Battelle, Pacific Northwest Laboratories and Nuclear Research Institute, ReZ. In the period from July 1994 to June 1995 two borosilicate glasses of special composition were prepared according to the PNL procedure and their physical and structural characteristics of glasses were studied. This Final Report contains a vast documentation on the properties of all glasses studied. For the preparation of the respective technology more detailed study of physico-chemical properties and crystallinity of investigated systems would be desirable.","Effect of chromium oxide on the properties of simulated nuclear waste glasses Abs: Sponsored by Department of Energy, Washington, DC. y of the effect of chromium on the properties of selected glasses was performed in the frame of a Contract between Battelle, Pacific Northwest Laboratories and Nuclear Research Institute, ReZ. In the period from July 1994 to June 1995 two borosilicate glasses of special composition were prepared according to the PNL procedure and their physical and structural characteristics of glasses were studied. This Final Report contains a vast documentation on the properties of all glasses studied. For the preparation of the respective technology more detailed study of physico-chemical properties and crystallinity of investigated systems would be desirable."
1510093,Hope and  Peterson 1996,"Pore water chromium concentration at 100-H Reactor Area adjacent to fall chinook salmon spawning habitat of the Hanford Reach, Columbia River. Revision 1","Sponsored by Department of Energy, Washington, DC. water underlying the 100-H Reactor Area discharges into the Columbia River in the vicinity of fall chinook salmon (Onchorynchus tshawytscha) spawning habitat within the Hanford Reach. Hexavalent chromium is a contaminant of concern that is found in the groundwater. The contaminant is considered toxic to aquatic ecological receptors, as its concentrations exceed the US Environmental Protection Agency's chronic ambient water quality criteria (AWQC) of 11 (mu)g/L. A methodology was designed and implemented to successfully obtain pore water samples from salmon spawning habitat located near the 100-H Reactor Area. Background data were obtained from three transacts, each containing two sample sites, upstream at Vemita Bar. Pore water was obtained from the substrate by divers from a depth of 46 cm (18 in.), which is deeper than the 10 to 40 cm (4 to 16 in.) substrate depth typically excavated by fall chinook salmon during spawning. Chromium was detected at levels above AWQC at three of 31 sample sites. One explanation for not detecting chromium at the remaining sites is that the interface between river water flowing within the substrate and groundwater upwelling into the substrate is below the 45 cm (18 in.) depth that was sampled. The potential impacts of contaminated groundwater discharge on the success of salmon spawning are uncertain.","Pore water chromium concentration at 100-H Reactor Area adjacent to fall chinook salmon spawning habitat of the Hanford Reach, Columbia River. Revision 1 Abs: Sponsored by Department of Energy, Washington, DC. water underlying the 100-H Reactor Area discharges into the Columbia River in the vicinity of fall chinook salmon (Onchorynchus tshawytscha) spawning habitat within the Hanford Reach. Hexavalent chromium is a contaminant of concern that is found in the groundwater. The contaminant is considered toxic to aquatic ecological receptors, as its concentrations exceed the US Environmental Protection Agency's chronic ambient water quality criteria (AWQC) of 11 (mu)g/L. A methodology was designed and implemented to successfully obtain pore water samples from salmon spawning habitat located near the 100-H Reactor Area. Background data were obtained from three transacts, each containing two sample sites, upstream at Vemita Bar. Pore water was obtained from the substrate by divers from a depth of 46 cm (18 in.), which is deeper than the 10 to 40 cm (4 to 16 in.) substrate depth typically excavated by fall chinook salmon during spawning. Chromium was detected at levels above AWQC at three of 31 sample sites. One explanation for not detecting chromium at the remaining sites is that the interface between river water flowing within the substrate and groundwater upwelling into the substrate is below the 45 cm (18 in.) depth that was sampled. The potential impacts of contaminated groundwater discharge on the success of salmon spawning are uncertain."
1510091,Thornton et al. 1995,Evaluation of chromium speciation and transport characteristics in the Hanford Site 100D and 100H areas,"Symposium on the hydrogeology of Washington state (1st), Olympia, WA (United States), 28-30 Aug 1995. Sponsored by Department of Energy, Washington, DC. and laboratory investigations have been conducted to define the fate and transport characteristics of chromium contamination present in the 100D/H Areas of the Hanford Site. This information is relevant to assessing the impact of the release of hexavalent chromium to the Columbia River. Included in this study was the determination of the concentration and aqueous speciation of chromium in the unconfined acquifer and an assessment of potential changes in speciation as groundwater passes through the river/acquifer transition zone and mixes with the Columbia River. The results of this study indicate that chromium present within the Hanford acquifer is predominantly in the oxidized hexavalent state. Chromium is apparently stable in the oxidized form owing to its lack of organic matter within the acquifer. A portion of the chromium is removed as groundwater passes through the transition zone due to reduction and precipitation associated with sediment/water interaction processes. Chemical data collected from seep water samples, however, suggests, that most of the hexavalent chromium ultimately discharges into the Columbia River. Dilution of hexavalent chromium subsequently occurs during the mixing of groundwater and river water, with relatively little change taking place in speciation.","Evaluation of chromium speciation and transport characteristics in the Hanford Site 100D and 100H areas Abs: Symposium on the hydrogeology of Washington state (1st), Olympia, WA (United States), 28-30 Aug 1995. Sponsored by Department of Energy, Washington, DC. and laboratory investigations have been conducted to define the fate and transport characteristics of chromium contamination present in the 100D/H Areas of the Hanford Site. This information is relevant to assessing the impact of the release of hexavalent chromium to the Columbia River. Included in this study was the determination of the concentration and aqueous speciation of chromium in the unconfined acquifer and an assessment of potential changes in speciation as groundwater passes through the river/acquifer transition zone and mixes with the Columbia River. The results of this study indicate that chromium present within the Hanford acquifer is predominantly in the oxidized hexavalent state. Chromium is apparently stable in the oxidized form owing to its lack of organic matter within the acquifer. A portion of the chromium is removed as groundwater passes through the transition zone due to reduction and precipitation associated with sediment/water interaction processes. Chemical data collected from seep water samples, however, suggests, that most of the hexavalent chromium ultimately discharges into the Columbia River. Dilution of hexavalent chromium subsequently occurs during the mixing of groundwater and river water, with relatively little change taking place in speciation."
1510090,Torres 1995,Removing hexavalent chromium from subsurface waters with anion-exchange resin,"Sponsored by Department of Energy, Washington, DC. ubsurface waters at Lawrence Livermore National Laboratory (LLNL) are contaminated with volatile organic compounds (VOCs). Hexavalent chromium, Cr(VI), is also present in the ground water; however, the source of the Cr(VI) may be natural. The planned treatment includes the following steps: (1) Pumping the water to the surface facility. (2) Purging the VOCs with air and absorbing them on activated carbon. (3) Filtering the water. (4) Passing the water through anion-exchange resin to remove the Cr. (5) Discharging the treated water into the local arroyos. This report describes laboratory experiments undertaken to learn how the proposed treatment facility can be expected to operate. The laboratory results are expected to supply vendors with the detailed performance specifications needed to prepare bids on the Cr removal portion of the treatment facility. The treatment facility is expected to process 60 gallons per minute (gpm) of water by stripping VOCs with 720 standard cubic feet per minute (scfm) of air and removing Cr(VI) with 60 cu ft of resin.","Removing hexavalent chromium from subsurface waters with anion-exchange resin Abs: Sponsored by Department of Energy, Washington, DC. ubsurface waters at Lawrence Livermore National Laboratory (LLNL) are contaminated with volatile organic compounds (VOCs). Hexavalent chromium, Cr(VI), is also present in the ground water; however, the source of the Cr(VI) may be natural. The planned treatment includes the following steps: (1) Pumping the water to the surface facility. (2) Purging the VOCs with air and absorbing them on activated carbon. (3) Filtering the water. (4) Passing the water through anion-exchange resin to remove the Cr. (5) Discharging the treated water into the local arroyos. This report describes laboratory experiments undertaken to learn how the proposed treatment facility can be expected to operate. The laboratory results are expected to supply vendors with the detailed performance specifications needed to prepare bids on the Cr removal portion of the treatment facility. The treatment facility is expected to process 60 gallons per minute (gpm) of water by stripping VOCs with 720 standard cubic feet per minute (scfm) of air and removing Cr(VI) with 60 cu ft of resin."
1510089,Pedersen 1995,Katalytisk rensning af gas fra halmforgasning. Parameterforsoeg. (Catalytic cleaning of gas from straw gasification. Parameter experiment),"Danish. EFP-91. s catalysts were tested in relation to different gas compositions and temperatures in order to find their modes of operation. The three types examined were a sulphidic one incorporating nickel and molybdenum on alumina, an oxidic one with chromium oxide on metal oxide and a metallic one with platinum on alumina and copper on silicate. The procedures for activation, regeneration, the operation of the catalyst systems and the process layout for the cleaning system were established. The platinum catalyst is too sensitive to the carbon monoxide in the gas for practical use. Too much carbon is produced at temperatures above 450 deg C and it is very expensive. The copper catalyst deactivates in the face of sulphur and can not be used. When temperatures are over 550 deg C the rate of sintering is too high in the case of the metal oxide and sulfidic catalyst which operates best at 400-550 deg C Those catalysts that are de-activated by carbon formation can be reactivated by burning up carbon compounds using recirculation of hot gas with an inlet temperature of 250 deg C Here the adiabatic rise in temperature must not exceed 550 deg C. One of the carbon substances identified reacts at a temperature of 100-150 deg C, the other at 250-300 deg C. An activation method was developed where watery methanol with a content of 50% is added to the hot recirculation circuit. During activation of the metal oxide catalyst the consumption of methanol is ca. 45 kg per cubic meter catalyst. For the sulphidic system consumption is ca. 10kg methanol and 60 kg carbon disulphide per cubic catalyst. (AB) (42 refs.)","Katalytisk rensning af gas fra halmforgasning. Parameterforsoeg. (Catalytic cleaning of gas from straw gasification. Parameter experiment) Abs: Danish. EFP-91. s catalysts were tested in relation to different gas compositions and temperatures in order to find their modes of operation. The three types examined were a sulphidic one incorporating nickel and molybdenum on alumina, an oxidic one with chromium oxide on metal oxide and a metallic one with platinum on alumina and copper on silicate. The procedures for activation, regeneration, the operation of the catalyst systems and the process layout for the cleaning system were established. The platinum catalyst is too sensitive to the carbon monoxide in the gas for practical use. Too much carbon is produced at temperatures above 450 deg C and it is very expensive. The copper catalyst deactivates in the face of sulphur and can not be used. When temperatures are over 550 deg C the rate of sintering is too high in the case of the metal oxide and sulfidic catalyst which operates best at 400-550 deg C Those catalysts that are de-activated by carbon formation can be reactivated by burning up carbon compounds using recirculation of hot gas with an inlet temperature of 250 deg C Here the adiabatic rise in temperature must not exceed 550 deg C. One of the carbon substances identified reacts at a temperature of 100-150 deg C, the other at 250-300 deg C. An activation method was developed where watery methanol with a content of 50% is added to the hot recirculation circuit. During activation of the metal oxide catalyst the consumption of methanol is ca. 45 kg per cubic meter catalyst. For the sulphidic system consumption is ca. 10kg methanol and 60 kg carbon disulphide per cubic catalyst. (AB) (42 refs.)"
1510088,Weisweiler et al. 1994,Dieselentstickung: NO(sub x)-Entfernung aus sauerstoffreichen Abgasen mittels NH(sub 3)-abspaltender Reduktionsmittel. (Denitrification of diesel pollutants: NO(sub x) removal from oxygen-rich exhaust by means of NH(sub 3) splitting reduction agents),"German. m of the work is found to minimize the amount of NO(sub X) in the exhaust of diesel engines by means of selective catalytic reduction. As catalysts zeolite-coated honeycombs of cordierite and as reducing agents aqueous solutions of NH(sub 3) forming substances like ammonium compounds or urea, cyanamide and guanidineacetate are used. The NO(sub X) conversion is determined as a function of temperature and reducing agent by applying a laboratory set-up. As an example, an Fe(sub 2)O(sub 3) activated zeolitic catalyst is used. Ammonium formiate as well as ammonium acetate containing solutions are found to be less effective in reducing NO(sub X) than the other ammonium compounds tested. It was verified that products formed by pyrolysis of HCOONH(sub 4) or CH(sub 3)COONH(sub 4) are adsorbed on the surface of the catalyst whereby its activity is decreased. In addition, the actual amount of NH(sub 3) generated by decomposition of the reducing agents is determined. Considering these results it is supposed that the conversion of NO(sub X) is partially decreased because HCOONH(sub 4) and CH(sub 3)COONH(sub 4) form less NH(sub 3) than theoretically expected. (orig.). 24 figs., 13 tabs., 28 refs.","Dieselentstickung: NO(sub x)-Entfernung aus sauerstoffreichen Abgasen mittels NH(sub 3)-abspaltender Reduktionsmittel. (Denitrification of diesel pollutants: NO(sub x) removal from oxygen-rich exhaust by means of NH(sub 3) splitting reduction agents) Abs: German. m of the work is found to minimize the amount of NO(sub X) in the exhaust of diesel engines by means of selective catalytic reduction. As catalysts zeolite-coated honeycombs of cordierite and as reducing agents aqueous solutions of NH(sub 3) forming substances like ammonium compounds or urea, cyanamide and guanidineacetate are used. The NO(sub X) conversion is determined as a function of temperature and reducing agent by applying a laboratory set-up. As an example, an Fe(sub 2)O(sub 3) activated zeolitic catalyst is used. Ammonium formiate as well as ammonium acetate containing solutions are found to be less effective in reducing NO(sub X) than the other ammonium compounds tested. It was verified that products formed by pyrolysis of HCOONH(sub 4) or CH(sub 3)COONH(sub 4) are adsorbed on the surface of the catalyst whereby its activity is decreased. In addition, the actual amount of NH(sub 3) generated by decomposition of the reducing agents is determined. Considering these results it is supposed that the conversion of NO(sub X) is partially decreased because HCOONH(sub 4) and CH(sub 3)COONH(sub 4) form less NH(sub 3) than theoretically expected. (orig.). 24 figs., 13 tabs., 28 refs."
1510086,Hsu 1995,Replacement inhibitors for tank farm cooling coil systems,"Sponsored by Department of Energy, Washington, DC. chromate has been an effective corrosion inhibitor for the cooling coil systems in Savannah River Site (SRS) waste tanks for over 40 years. Due to their age and operating history, cooling coils occasionally fail allowing chromate water to leak into the environment. The cost of reporting and cleaning up chromate spills prompted High Level Waste Engineering (HLWE) to initiate a study to investigate alternative tank cooling water inhibitor systems and the associated cost of replacement. Several inhibitor systems were investigated as potential alternatives to sodium chromate. However, the conversion cost is estimated to be $8.5 million over a period of 8 to 12 months to convert all 5 cooling systems. Although each of the alternative inhibitors examined is effective in preventing corrosion, there is no inhibitor identified that is as effective as chromate. Assuming 3 major leaks a year (the average over the past several years), the cost of maintaining the existing inhibitor was estimated at $0.5 million per year. Since there is no economic or regulatory incentive to replace the sodium chromate with an alternate inhibitor, HLWE recommends that sodium chromate continue to be used as the inhibitor for the waste tank cooling systems.","Replacement inhibitors for tank farm cooling coil systems Abs: Sponsored by Department of Energy, Washington, DC. chromate has been an effective corrosion inhibitor for the cooling coil systems in Savannah River Site (SRS) waste tanks for over 40 years. Due to their age and operating history, cooling coils occasionally fail allowing chromate water to leak into the environment. The cost of reporting and cleaning up chromate spills prompted High Level Waste Engineering (HLWE) to initiate a study to investigate alternative tank cooling water inhibitor systems and the associated cost of replacement. Several inhibitor systems were investigated as potential alternatives to sodium chromate. However, the conversion cost is estimated to be $8.5 million over a period of 8 to 12 months to convert all 5 cooling systems. Although each of the alternative inhibitors examined is effective in preventing corrosion, there is no inhibitor identified that is as effective as chromate. Assuming 3 major leaks a year (the average over the past several years), the cost of maintaining the existing inhibitor was estimated at $0.5 million per year. Since there is no economic or regulatory incentive to replace the sodium chromate with an alternate inhibitor, HLWE recommends that sodium chromate continue to be used as the inhibitor for the waste tank cooling systems."
1510085,Imrich 1995,Degradation of a N06690 borescope in a radioactive waste/glass melter system,"International conference on heat resistant materials (2nd), Gatlinburg, TN (United States), 11-14 Sep 1995. Sponsored by Department of Energy, Washington, DC. ctive liquid waste from nuclear materials production processes wi11 be vitrified in the Defense Waste Process Facility (DWPF) melter. The melter borescope outer housing, fabricated from N06690, was severely degraded by the combined effects of corrosion and oxidation after only five months of non radioactive operation. The melter was idled and not being fed over 85% of the time during the cold run operations. The borescope was designed to perform in an oxygen rich, chloride containing environment with temperatures approaching 900(degree)C (1650(degree)F). The housing was designed for a minimum of two years of continuous service in the DWPF melter. Air and steam were purged through the borescope and swept over the optics assembly to keep molten glass and volatile gases from depositing on the lens cover. Upon exiting the borescope the air passes through a N06690 orifice and enters the melter. Severe oxidation was observed around the orifice. Extensive material loss was also observed on the side of the outer housing which protrudes through the dome of the melter. Redesign of the borescope is currently underway and will include a new set of optics that will allow the size of the orifice to be significantly decreased, thus reducing the amount of air necessary to keep the lens cover clean. Application of a duplex diffusion coating, consisting of chromium and aluminum, on the end of the borescope outer housing and the use of an inert gas purge are also being considered.","Degradation of a N06690 borescope in a radioactive waste/glass melter system Abs: International conference on heat resistant materials (2nd), Gatlinburg, TN (United States), 11-14 Sep 1995. Sponsored by Department of Energy, Washington, DC. ctive liquid waste from nuclear materials production processes wi11 be vitrified in the Defense Waste Process Facility (DWPF) melter. The melter borescope outer housing, fabricated from N06690, was severely degraded by the combined effects of corrosion and oxidation after only five months of non radioactive operation. The melter was idled and not being fed over 85% of the time during the cold run operations. The borescope was designed to perform in an oxygen rich, chloride containing environment with temperatures approaching 900(degree)C (1650(degree)F). The housing was designed for a minimum of two years of continuous service in the DWPF melter. Air and steam were purged through the borescope and swept over the optics assembly to keep molten glass and volatile gases from depositing on the lens cover. Upon exiting the borescope the air passes through a N06690 orifice and enters the melter. Severe oxidation was observed around the orifice. Extensive material loss was also observed on the side of the outer housing which protrudes through the dome of the melter. Redesign of the borescope is currently underway and will include a new set of optics that will allow the size of the orifice to be significantly decreased, thus reducing the amount of air necessary to keep the lens cover clean. Application of a duplex diffusion coating, consisting of chromium and aluminum, on the end of the borescope outer housing and the use of an inert gas purge are also being considered."
1510084,Thompson 1995,"Case History of a Clean Water Act Compliance Agreement at the Rocky Flats Environmental Technology Site near Golden, Colorado","Environmental remediation conference: committed to results, Denver, CO (United States), 13-18 Aug 1995. Sponsored by Department of Energy, Washington, DC. r Clean Water Act (CWA) Federal Facilities Compliance Agreement was signed on March 25, 1991 by the US Department of Energy, Rocky Flats Field Office (DOE, RFFO) and the Water Enforcement Division of the Environmental Protection Agency (EPA), Region VIII. The agreement revised the Rocky Flats Plant's National Pollutant Discharge Elimination System (NPDES) permit and arose from pemittee-requested changes in effluent monitoring points and permit violations, most notably the February 22, 1989 Chromic Acid Incident. The Compliance Agreement, hereafter referred to as the NPDES FFCA, called for three separate remedial action plans and contained a schedule for their submittal to the EPA. The compliance plans focused on: (1) Waste Water Treatment Plant (WWTP) performance upgrades, (2) source control and surface water protection, and (3) characterization of the impacts from past sludge disposal practices. Projects that implemented the compliance plans were initiated soon after submittal to the EPA and are forecast to complete in 1997 at a total cost of over $35 million. This paper presents a case history of NPDES FFCA compliance projects and highlights the successes, failures, and lessons learned.","Case History of a Clean Water Act Compliance Agreement at the Rocky Flats Environmental Technology Site near Golden, Colorado Abs: Environmental remediation conference: committed to results, Denver, CO (United States), 13-18 Aug 1995. Sponsored by Department of Energy, Washington, DC. r Clean Water Act (CWA) Federal Facilities Compliance Agreement was signed on March 25, 1991 by the US Department of Energy, Rocky Flats Field Office (DOE, RFFO) and the Water Enforcement Division of the Environmental Protection Agency (EPA), Region VIII. The agreement revised the Rocky Flats Plant's National Pollutant Discharge Elimination System (NPDES) permit and arose from pemittee-requested changes in effluent monitoring points and permit violations, most notably the February 22, 1989 Chromic Acid Incident. The Compliance Agreement, hereafter referred to as the NPDES FFCA, called for three separate remedial action plans and contained a schedule for their submittal to the EPA. The compliance plans focused on: (1) Waste Water Treatment Plant (WWTP) performance upgrades, (2) source control and surface water protection, and (3) characterization of the impacts from past sludge disposal practices. Projects that implemented the compliance plans were initiated soon after submittal to the EPA and are forecast to complete in 1997 at a total cost of over $35 million. This paper presents a case history of NPDES FFCA compliance projects and highlights the successes, failures, and lessons learned."
1510083,Steffani and  Meltzer 1995,Electrodeposited tungsten-nickel-boron: A replacement for hexavalent chromium,"Sponsored by Department of Energy, Washington, DC. um, deposited from acidic solutions of its hexavalent ion, has been the rule for wear resistant, corrosion resistant coatings for many years. Although chromium coatings are durable, the plating process generates air emissions, effluent rinse waters, and process solutions that are toxic, suspected carcinogens, and a risk to human health and the environment. Tungsten-nickel-boron (W-Ni-B) alloy deposition is a potential substitute for hexavalent chrome. It has excellent wear, corrosion, and mechanical properties and also may be less of an environmental risk. This study examines the electroplating process and deposit properties of W-Ni-B and compares them with those of hexavalent chrome.","Electrodeposited tungsten-nickel-boron: A replacement for hexavalent chromium Abs: Sponsored by Department of Energy, Washington, DC. um, deposited from acidic solutions of its hexavalent ion, has been the rule for wear resistant, corrosion resistant coatings for many years. Although chromium coatings are durable, the plating process generates air emissions, effluent rinse waters, and process solutions that are toxic, suspected carcinogens, and a risk to human health and the environment. Tungsten-nickel-boron (W-Ni-B) alloy deposition is a potential substitute for hexavalent chrome. It has excellent wear, corrosion, and mechanical properties and also may be less of an environmental risk. This study examines the electroplating process and deposit properties of W-Ni-B and compares them with those of hexavalent chrome."
1510082,Hrma and  Smith 1994,Effect of vitrification technology on waste loading,"International nuclear and hazardous waste management conference, Atlanta, GA (United States), 14-18 Aug 1994. Sponsored by Department of Energy, Washington, DC. ctive wastes on the Hanford Site are going to be permanently disposed of by incorporation into a durable glass. These wastes will be separated into low and high-level portions, and then vitrified. The low-level waste (LLW) is water soluble. Its vitrifiable part (other than off-gas) contains approximately 80 wt% Na(sub 2)O, the rest being Al(sub 2)O(sub 3), P(sub 2)O(sub 5), K(sub 2)O, and minor components. The challenge is to formulate durable LLW glasses with as high Na(sub 2)O content as possible by optimizing the additions of SiO(sub 2), Al(sub 2)O(sub 3), B(sub 2)O(sub 3), CaO, and ZrO(sub 2). This task will not be simple, considering the non-linear and interactive nature of glass properties as a function of composition. Once developed, the LLW glass, being similar in composition to commercial glasses, is unlikely to cause major processing problems, such as crystallization or molten salt segregation. For example, inexpensive LLW glass can be produced in a high-capacity Joule-heated melter with a cold cap to minimize volatilization. The high-level waste (HLW) consists of water-insoluble sludge (Fe(sub 2)O(sub 3), Al(sub 2)O(sub 3), ZrO(sub 2), Cr(sub 2)O(sub 3), NiO, and others) and a substantial water-soluble residue (Na(sub 2)O). Most of the water-insoluble components are refractory; i.e., their melting points are above the glass melting temperature. With regard to product acceptability, the maximum loading of Hanford HLW in the glass is limited by product durability, not by radiolytic heat generation. However, this maximum may not be achievable because of technological constraints imposed by melter feed rheology, frit properties, and glass melter limits. These restrictions are discussed in this paper. 38 refs.","Effect of vitrification technology on waste loading Abs: International nuclear and hazardous waste management conference, Atlanta, GA (United States), 14-18 Aug 1994. Sponsored by Department of Energy, Washington, DC. ctive wastes on the Hanford Site are going to be permanently disposed of by incorporation into a durable glass. These wastes will be separated into low and high-level portions, and then vitrified. The low-level waste (LLW) is water soluble. Its vitrifiable part (other than off-gas) contains approximately 80 wt% Na(sub 2)O, the rest being Al(sub 2)O(sub 3), P(sub 2)O(sub 5), K(sub 2)O, and minor components. The challenge is to formulate durable LLW glasses with as high Na(sub 2)O content as possible by optimizing the additions of SiO(sub 2), Al(sub 2)O(sub 3), B(sub 2)O(sub 3), CaO, and ZrO(sub 2). This task will not be simple, considering the non-linear and interactive nature of glass properties as a function of composition. Once developed, the LLW glass, being similar in composition to commercial glasses, is unlikely to cause major processing problems, such as crystallization or molten salt segregation. For example, inexpensive LLW glass can be produced in a high-capacity Joule-heated melter with a cold cap to minimize volatilization. The high-level waste (HLW) consists of water-insoluble sludge (Fe(sub 2)O(sub 3), Al(sub 2)O(sub 3), ZrO(sub 2), Cr(sub 2)O(sub 3), NiO, and others) and a substantial water-soluble residue (Na(sub 2)O). Most of the water-insoluble components are refractory; i.e., their melting points are above the glass melting temperature. With regard to product acceptability, the maximum loading of Hanford HLW in the glass is limited by product durability, not by radiolytic heat generation. However, this maximum may not be achievable because of technological constraints imposed by melter feed rheology, frit properties, and glass melter limits. These restrictions are discussed in this paper. 38 refs."
1510081,Allan and  Kukacka 1994,In-situ containment and stabilization of buried waste: Annual report FY 1994,"Progress rept. red by Department of Energy, Washington, DC. o landfills of specific interest are the Chemical Waste Landfill (CWL) and the Mixed Waste Landfill (MWL), both located at Sandia National Laboratory. The work is comprised of two subtasks: (1) In-Situ Barriers and (2) In-Situ Stabilization of Contaminated Soils. The main environmental concern at the CWL is a chromium plume resulting from disposal of chromic acid and chromic sulfuric acid into unlined pits. This program has investigated means of in-situ stabilization of chromium contaminated soils and placement of containment barriers around the CWL. The MWL contains a plume of tritiated water. In-situ immobilization of tritiated water with cementitious grouts was not considered to be a method with a high probability of success and was not pursued. This is discussed further in Section 5.0. Containment barriers for the tritium plume were investigated. FY 94 work focused on stabilization of chromium contaminated soil with blast furnace slag modified grouts to bypass the stage of pre-reduction of Cr(6), barriers for tritiated water containment at the MWL, continued study of barriers for the CWL, and jet grouting field trials for CWL barriers at an uncontaminated site at SNL. Cores from the FY 93 permeation grouting field trails were also tested in FY 94.","In-situ containment and stabilization of buried waste: Annual report FY 1994 Abs: Progress rept. red by Department of Energy, Washington, DC. o landfills of specific interest are the Chemical Waste Landfill (CWL) and the Mixed Waste Landfill (MWL), both located at Sandia National Laboratory. The work is comprised of two subtasks: (1) In-Situ Barriers and (2) In-Situ Stabilization of Contaminated Soils. The main environmental concern at the CWL is a chromium plume resulting from disposal of chromic acid and chromic sulfuric acid into unlined pits. This program has investigated means of in-situ stabilization of chromium contaminated soils and placement of containment barriers around the CWL. The MWL contains a plume of tritiated water. In-situ immobilization of tritiated water with cementitious grouts was not considered to be a method with a high probability of success and was not pursued. This is discussed further in Section 5.0. Containment barriers for the tritium plume were investigated. FY 94 work focused on stabilization of chromium contaminated soil with blast furnace slag modified grouts to bypass the stage of pre-reduction of Cr(6), barriers for tritiated water containment at the MWL, continued study of barriers for the CWL, and jet grouting field trials for CWL barriers at an uncontaminated site at SNL. Cores from the FY 93 permeation grouting field trails were also tested in FY 94."
1510080,Liszewski and  Mann 1993,"Concentrations of 23 trace elements in ground water and surface water at and near the Idaho National Engineering Laboratory, Idaho, 1988--91","Sponsored by Department of Energy, Washington, DC. ical data for 23 trace elements are reported for ground- and surface-water samples collected at and near the Idaho National Engineering Laboratory during 1988--91. Water samples were collected from 148 wells completed in the Snake River Plain aquifer, 18 wells completed in discontinuous deep perched-water zones, and 1 well completed in an alluvial aquifer. Surface-water samples also were collected from three streams, two springs, two ponds, and one lake. Data are categorized by concentrations of total recoverable of dissolved trace elements. Concentrations of total recoverable trace elements are reported for unfiltered water samples and include results for one or more of the following: aluminum, arsenic, barium, beryllium, cadmium, chromium, cobalt, copper, iron, lead, manganese, mercury, nickel, selenium, silver, and zinc. Concentrations of dissolved trace elements are reported for water samples filtered through a nominal 0.45-micron filter and may also include bromide, fluoride, lithium, molybdenum, strontium, thallium, and vanadium. Concentrations of dissolved hexavalent chromium also are reported for many samples. The water samples were analyzed at the US Geological Survey's National Water Quality Laboratory in Arvada, Colorado. Methods used to collect the water samples and quality assurance instituted for the sampling program are described. Concentrations of chromium equaled or exceeded the maximum contaminant level at 12 ground-water quality monitoring wells. Other trace elements did not exceed their respective maximum contaminant levels.","Concentrations of 23 trace elements in ground water and surface water at and near the Idaho National Engineering Laboratory, Idaho, 1988--91 Abs: Sponsored by Department of Energy, Washington, DC. ical data for 23 trace elements are reported for ground- and surface-water samples collected at and near the Idaho National Engineering Laboratory during 1988--91. Water samples were collected from 148 wells completed in the Snake River Plain aquifer, 18 wells completed in discontinuous deep perched-water zones, and 1 well completed in an alluvial aquifer. Surface-water samples also were collected from three streams, two springs, two ponds, and one lake. Data are categorized by concentrations of total recoverable of dissolved trace elements. Concentrations of total recoverable trace elements are reported for unfiltered water samples and include results for one or more of the following: aluminum, arsenic, barium, beryllium, cadmium, chromium, cobalt, copper, iron, lead, manganese, mercury, nickel, selenium, silver, and zinc. Concentrations of dissolved trace elements are reported for water samples filtered through a nominal 0.45-micron filter and may also include bromide, fluoride, lithium, molybdenum, strontium, thallium, and vanadium. Concentrations of dissolved hexavalent chromium also are reported for many samples. The water samples were analyzed at the US Geological Survey's National Water Quality Laboratory in Arvada, Colorado. Methods used to collect the water samples and quality assurance instituted for the sampling program are described. Concentrations of chromium equaled or exceeded the maximum contaminant level at 12 ground-water quality monitoring wells. Other trace elements did not exceed their respective maximum contaminant levels."
1510079,Feng et al. 1994,Comparison of glassy slag waste forms produced in laboratory crucibles and in a bench-scale plasma furnace,"American Chemical Society meeting on industrial and engineering chemistry, Atlanta, GA (United States), 19-21 Sep 1994. Sponsored by Department of Energy, Washington, DC. ication is currently the best demonstrated available technology for the disposal of high-level radioactive wastes. An innovative vitrification approach known as minimum additive waste stabilization (MAWS) is being developed. Both homogeneous glass and glassy slags have been used in implementing MAWS. Glassy slags (vitro-ceramics) are glass-crystal composites, and they are composed of various metal oxide crystalline phases embedded in an aluminosilicate glass matrix. Glassy slags with compositions developed in crucible melts at Argonne National Laboratory (ANL) were successfully produced in a bench-scale Retech plasma centrifugal furnace (PCF) by MSE, Inc. Detailed examinations of these materials showed that the crucible melts and the PCF produced similar glass and crystalline phases. The two sets of glassy slags exhibited similar chemical durability in terms of normalized releases of their major components. The slags produced in the PCF furnace using metals were usually less oxidized, although this had no effect on the corrosion behavior of the major components of the slags. However, the normalized release rate of cerium was initially lower for the PCF slags. This difference diminished with time as the redox sates of the metal oxides in slags began to be controlled by exposure to air in the tests. Thus, the deference in cerium release due to the differences in slag redox state may be transitory. The cerium solubility is a complex function of redox state and solution pH and Eh.","Comparison of glassy slag waste forms produced in laboratory crucibles and in a bench-scale plasma furnace Abs: American Chemical Society meeting on industrial and engineering chemistry, Atlanta, GA (United States), 19-21 Sep 1994. Sponsored by Department of Energy, Washington, DC. ication is currently the best demonstrated available technology for the disposal of high-level radioactive wastes. An innovative vitrification approach known as minimum additive waste stabilization (MAWS) is being developed. Both homogeneous glass and glassy slags have been used in implementing MAWS. Glassy slags (vitro-ceramics) are glass-crystal composites, and they are composed of various metal oxide crystalline phases embedded in an aluminosilicate glass matrix. Glassy slags with compositions developed in crucible melts at Argonne National Laboratory (ANL) were successfully produced in a bench-scale Retech plasma centrifugal furnace (PCF) by MSE, Inc. Detailed examinations of these materials showed that the crucible melts and the PCF produced similar glass and crystalline phases. The two sets of glassy slags exhibited similar chemical durability in terms of normalized releases of their major components. The slags produced in the PCF furnace using metals were usually less oxidized, although this had no effect on the corrosion behavior of the major components of the slags. However, the normalized release rate of cerium was initially lower for the PCF slags. This difference diminished with time as the redox sates of the metal oxides in slags began to be controlled by exposure to air in the tests. Thus, the deference in cerium release due to the differences in slag redox state may be transitory. The cerium solubility is a complex function of redox state and solution pH and Eh."
1510078,Lipp 1993,Tiefenaufgeloeste Bestimmung von Schwermetallverbindungen in Schweissrauchpartikeln. (Depth-resolved determination of heavy metal components in welding fume),"Diss. . g of stainless steel causes the emission of fume particles containing large amounts of heavy metals, such as nickel and chromium. All nickel compounts and the hexavalent chromium are toxic and cancerogen, while trivalent chromium is mainly non-hazardous. The depth distribution of the constituents in the particles reflects the mechanism of formation and, moreover, determined the effect of the noxious compounds. Based on Secondary Neutral Mass Spectrometry (SNMS) and Secondary Ion Mass Spectrometry (SIMS) an analytical method was developed for quantification, identification and localisation of the heavy metal compounts on and in welding fume particles. (orig.)","Tiefenaufgeloeste Bestimmung von Schwermetallverbindungen in Schweissrauchpartikeln. (Depth-resolved determination of heavy metal components in welding fume) Abs: Diss. . g of stainless steel causes the emission of fume particles containing large amounts of heavy metals, such as nickel and chromium. All nickel compounts and the hexavalent chromium are toxic and cancerogen, while trivalent chromium is mainly non-hazardous. The depth distribution of the constituents in the particles reflects the mechanism of formation and, moreover, determined the effect of the noxious compounds. Based on Secondary Neutral Mass Spectrometry (SNMS) and Secondary Ion Mass Spectrometry (SIMS) an analytical method was developed for quantification, identification and localisation of the heavy metal compounts on and in welding fume particles. (orig.)"
1510077,Shukla and  Folsom 1994,Remediation of ground water containing volatile organic compounds and tritium,"Federal environmental restoration and waste minimization conference and exhibition, New Orleans, LA (United States), 25-29 Apr 1994. Sponsored by Department of Energy, Washington, DC. ailer 5475 (T-5475) East Taxi Strip Area at Lawrence Livermore National Laboratory (LLNL), Livermore, California was used as a taxi strip by the US Navy to taxi airplanes to the runway from 1942 to 1947. Solvents were used in some unpaved areas adjacent to the East Taxi Strip for cleaning airplanes. From 1953 through 1976, the area was used to store and treat liquid waste. From 1962 to 1976 ponds were constructed and used for evaporation of liquid waste. As a result, the ground water in this area contains volatile organic compounds (VOCs) and tritium. The ground water in this area is also known to contain hexavalent chromium that is probably naturally occurring. Therefore, LLNL has proposed ''pump-and-treat'' technology above grade in a completely closed loop system. The facility will be designed to remove the VOCs and hexavalent chromium, if any, from the ground water, and the treated ground water containing tritium will be reinjected where it will decay naturally in the subsurface. Ground water containing tritium will be reinjected into areas with equal or higher tritium concentrations to comply with California regulations.","Remediation of ground water containing volatile organic compounds and tritium Abs: Federal environmental restoration and waste minimization conference and exhibition, New Orleans, LA (United States), 25-29 Apr 1994. Sponsored by Department of Energy, Washington, DC. ailer 5475 (T-5475) East Taxi Strip Area at Lawrence Livermore National Laboratory (LLNL), Livermore, California was used as a taxi strip by the US Navy to taxi airplanes to the runway from 1942 to 1947. Solvents were used in some unpaved areas adjacent to the East Taxi Strip for cleaning airplanes. From 1953 through 1976, the area was used to store and treat liquid waste. From 1962 to 1976 ponds were constructed and used for evaporation of liquid waste. As a result, the ground water in this area contains volatile organic compounds (VOCs) and tritium. The ground water in this area is also known to contain hexavalent chromium that is probably naturally occurring. Therefore, LLNL has proposed ''pump-and-treat'' technology above grade in a completely closed loop system. The facility will be designed to remove the VOCs and hexavalent chromium, if any, from the ground water, and the treated ground water containing tritium will be reinjected where it will decay naturally in the subsurface. Ground water containing tritium will be reinjected into areas with equal or higher tritium concentrations to comply with California regulations."
1510076,Abbasian et al. 1994,"Development of novel copper-based sorbents for hot-gas cleanup. Technical report, 1 March--31 May 1994","Progress rept. red by Department of Energy, Washington, DC. jective of this investigation is to evaluate two novel copper-based sorbents, namely copper-chromium and copper-cerium, for their effectiveness in removing hydrogen sulfide from fuel gas in the temperature range of 650 to 850 C. Such high temperatures will be required for the new generation of gas turbines (inlet &amp;gt; 750 C) in Integrated Gasification Combined Cycle (IGCC) systems. Results of fixed-bed reactor tests conducted in this quarter, indicate that, at 750 C, pre-reduction with H(sub 2) in the presence of H(sub 2)O does not effect the performance of either sorbent for H(sub 2)S removal. For the pre-reduced CuCr(sub 2)O(sub 4) sorbent, copper utilization before the first H(sub 2)S breakthrough is substantially higher in synthesis feed gas mixture than in feed gas containing 30 Vol% H(sub 2), and slightly lower than in 10 vol% H(sub 2). In sulfidation-regeneration testing of copper- and additive-rich sorbents, chromium-rich CuO-3Cr(sub 2)O(sub 4) sorbent demonstrated very high H(sub 2)S removal efficiency and high copper conversion levels (comparable to that of the 1:1 molar composition sorbent). Similar results were obtained with the cerium-rich CuO-3CeO(sub 2) sorbent, but only for the first cycle. The H(sub 2)S removal performance of both copper-rich sorbents was inferior to that of the respective 1:1 molar compositions. CuO-CeO(sub 2) sorbent testing in a TGA indicates no appreciable decrease in the sulfidation rate over 5 1/2 cycles. However, weight changes during regeneration of the CuO-CeO(sub 2) suggest that some copper or cerium sulfates formed.","Development of novel copper-based sorbents for hot-gas cleanup. Technical report, 1 March--31 May 1994 Abs: Progress rept. red by Department of Energy, Washington, DC. jective of this investigation is to evaluate two novel copper-based sorbents, namely copper-chromium and copper-cerium, for their effectiveness in removing hydrogen sulfide from fuel gas in the temperature range of 650 to 850 C. Such high temperatures will be required for the new generation of gas turbines (inlet &amp;gt; 750 C) in Integrated Gasification Combined Cycle (IGCC) systems. Results of fixed-bed reactor tests conducted in this quarter, indicate that, at 750 C, pre-reduction with H(sub 2) in the presence of H(sub 2)O does not effect the performance of either sorbent for H(sub 2)S removal. For the pre-reduced CuCr(sub 2)O(sub 4) sorbent, copper utilization before the first H(sub 2)S breakthrough is substantially higher in synthesis feed gas mixture than in feed gas containing 30 Vol% H(sub 2), and slightly lower than in 10 vol% H(sub 2). In sulfidation-regeneration testing of copper- and additive-rich sorbents, chromium-rich CuO-3Cr(sub 2)O(sub 4) sorbent demonstrated very high H(sub 2)S removal efficiency and high copper conversion levels (comparable to that of the 1:1 molar composition sorbent). Similar results were obtained with the cerium-rich CuO-3CeO(sub 2) sorbent, but only for the first cycle. The H(sub 2)S removal performance of both copper-rich sorbents was inferior to that of the respective 1:1 molar compositions. CuO-CeO(sub 2) sorbent testing in a TGA indicates no appreciable decrease in the sulfidation rate over 5 1/2 cycles. However, weight changes during regeneration of the CuO-CeO(sub 2) suggest that some copper or cerium sulfates formed."
1510075,Mccain and  Baechler 1994,Field screening for hexavalent chromium in soil: A fast-turnaround field method based on water extraction,"Annual West Coast conference on contaminated soils and groundwater (5th), Long Beach, CA (United States), 28 Mar - 1 Apr 1994. Sponsored by Department of Energy, Washington, DC. dichromate has been identified as a contaminant of concern at several waste sites on the Hanford Site. Although chromium standards for soil are typically stated in terms of total chrome, much of the toxicity and carcinogenicity are attributed to the hexavalent state, which typically exists as a relatively mobile anion. Investigation and removal of crushed drums potentially containing residual sodium dichromate required a field test for hexavalent chromium to support characterization and remediation activities. Previous experience with a commercially available field test kit had been unsuccessful. This stimulated an effort to determine potential sources of error in the field test and led to a number of modifications that significantly improved the reliability of the test.","Field screening for hexavalent chromium in soil: A fast-turnaround field method based on water extraction Abs: Annual West Coast conference on contaminated soils and groundwater (5th), Long Beach, CA (United States), 28 Mar - 1 Apr 1994. Sponsored by Department of Energy, Washington, DC. dichromate has been identified as a contaminant of concern at several waste sites on the Hanford Site. Although chromium standards for soil are typically stated in terms of total chrome, much of the toxicity and carcinogenicity are attributed to the hexavalent state, which typically exists as a relatively mobile anion. Investigation and removal of crushed drums potentially containing residual sodium dichromate required a field test for hexavalent chromium to support characterization and remediation activities. Previous experience with a commercially available field test kit had been unsuccessful. This stimulated an effort to determine potential sources of error in the field test and led to a number of modifications that significantly improved the reliability of the test."
1510074,Abbasian et al. 1994,"Development of novel copper-based sorbents for hot-gas cleanup. (Quarterly) technical report, December 1, 1993--February 28, 1994","Progress rept. red by Department of Energy, Washington, DC. jective of this investigation is to evaluate two novel copper-based sorbents, namely copper-chromium and copper-cerium, for their effectiveness in removing hydrogen sulfide from fuel gas in the temperature range of 650(degree) to 850(degree). Such high temperatures will be required for the new generation of gas turbines (inlet &amp;gt;750(degree)C) in Integrated Gasification Combined Cycle (IGCC) systems. The effect of pre-reduction with H(sub 2), in the presence of H(sub 2)O on the performance of the sorbents in cyclic sulfidation/regeneration, was studied in a thermogravimetric analyzer (TGA) and in a fixed-bed reactor at 750(degree)C. The results of the TGA tests indicate that pre-reduction of the sorbents is very fast in either 10% or 30% H(sub 2). Without sorbent pre-reduction, sulfidation consists of two-stages, a reduction-dominating and a sulfidation-dominating stage. Sulfidation apparently takes place before reduction is complete. During regeneration some copper/cerium sulfates may have formed and Cu(sub 2)O may have formed in addition to CuO. The fixed-bed reactor tests show that at 750(degree)C: (1) prereducing the CuO-Cr(sub 2)O(sub 3) with H(sub 2) does not effect the reactivity of the sorbent towards H(sub 2)S at either the high or low H(sub 2) feed gas concentrations and (2) when 30% H(sub 2) was used during sulfidation of either sorbent, the first H(sub 2)S breakthrough occurs earlier than when 10% H(sub 2) was used.","Development of novel copper-based sorbents for hot-gas cleanup. (Quarterly) technical report, December 1, 1993--February 28, 1994 Abs: Progress rept. red by Department of Energy, Washington, DC. jective of this investigation is to evaluate two novel copper-based sorbents, namely copper-chromium and copper-cerium, for their effectiveness in removing hydrogen sulfide from fuel gas in the temperature range of 650(degree) to 850(degree). Such high temperatures will be required for the new generation of gas turbines (inlet &amp;gt;750(degree)C) in Integrated Gasification Combined Cycle (IGCC) systems. The effect of pre-reduction with H(sub 2), in the presence of H(sub 2)O on the performance of the sorbents in cyclic sulfidation/regeneration, was studied in a thermogravimetric analyzer (TGA) and in a fixed-bed reactor at 750(degree)C. The results of the TGA tests indicate that pre-reduction of the sorbents is very fast in either 10% or 30% H(sub 2). Without sorbent pre-reduction, sulfidation consists of two-stages, a reduction-dominating and a sulfidation-dominating stage. Sulfidation apparently takes place before reduction is complete. During regeneration some copper/cerium sulfates may have formed and Cu(sub 2)O may have formed in addition to CuO. The fixed-bed reactor tests show that at 750(degree)C: (1) prereducing the CuO-Cr(sub 2)O(sub 3) with H(sub 2) does not effect the reactivity of the sorbent towards H(sub 2)S at either the high or low H(sub 2) feed gas concentrations and (2) when 30% H(sub 2) was used during sulfidation of either sorbent, the first H(sub 2)S breakthrough occurs earlier than when 10% H(sub 2) was used."
1510073,Chen et al. 1994,"Superior catalysts for selective catalytic reduction of nitric oxide. Quarterly technical progress report, 1 January 1994--31 March 1994","Sponsored by Department of Energy, Washington, DC. the past quarter, progress has been made in four tasks as summarized below: Task 1: A delaminated Fe(sub 2)O(sub 3) pillared clay was synthesized and carefully characterized. The chemical composition was measured by ICP atomic emission spectrometry. The structural changes in the clay as well as the iron oxide particle sizes were characterized by X-ray diffraction techniques. Task 2: The Selective Catalytic Reduction (SCR, i.e., NO reduction with NH(sub 3)) activities of the delaminated pillared clay were tested and compared with four other most active SCR catalysts: a commercial V(sub 2)O(sub 5) + WO(sub 3)/TiO(sub 2) catalyst, a Fe(sub 2)O(sub 3)-pillared clay, and two supported Fe(sub 2)O(sub 3) catalysts (on Al(sub 2)O(sub 3) and TiO(sub 2)). The delaminated Fe(sub 2)O(sub 3) pillared clay exhibited the highest SCR activities. Catalyst stability test showed that the delaminated sample was also stable. Task 3: To further increase the SCR activity of the delaminated pillared clay, Cr(sub 2)O(sub 3) was doped as a promoter by incipient wetness. Task 4: Deactivation effects of SO(sub 2) and H(sub 2)O on the SCR activities of the delaminated Fe(sub 2)O(sub 3) pillared clay were studied, and compared with other SCR catalysts. The delaminated clay catalyst showed the least deactivation.","Superior catalysts for selective catalytic reduction of nitric oxide. Quarterly technical progress report, 1 January 1994--31 March 1994 Abs: Sponsored by Department of Energy, Washington, DC. the past quarter, progress has been made in four tasks as summarized below: Task 1: A delaminated Fe(sub 2)O(sub 3) pillared clay was synthesized and carefully characterized. The chemical composition was measured by ICP atomic emission spectrometry. The structural changes in the clay as well as the iron oxide particle sizes were characterized by X-ray diffraction techniques. Task 2: The Selective Catalytic Reduction (SCR, i.e., NO reduction with NH(sub 3)) activities of the delaminated pillared clay were tested and compared with four other most active SCR catalysts: a commercial V(sub 2)O(sub 5) + WO(sub 3)/TiO(sub 2) catalyst, a Fe(sub 2)O(sub 3)-pillared clay, and two supported Fe(sub 2)O(sub 3) catalysts (on Al(sub 2)O(sub 3) and TiO(sub 2)). The delaminated Fe(sub 2)O(sub 3) pillared clay exhibited the highest SCR activities. Catalyst stability test showed that the delaminated sample was also stable. Task 3: To further increase the SCR activity of the delaminated pillared clay, Cr(sub 2)O(sub 3) was doped as a promoter by incipient wetness. Task 4: Deactivation effects of SO(sub 2) and H(sub 2)O on the SCR activities of the delaminated Fe(sub 2)O(sub 3) pillared clay were studied, and compared with other SCR catalysts. The delaminated clay catalyst showed the least deactivation."
1510072,Abbasian et al. 1994,"Development of novel copper-based sorbents for hot-gas cleanup. (Quarterly) technical report, September 1--November 30, 1993","Progress rept. red by Department of Energy, Washington, DC. jective of this investigation is to evaluate two novel copper-based sorbents, namely copper-chromium and copper-cerium, for their effectiveness in removing hydrogen sulfide from fuel gas in the temperature range of 650(degree) to 850(degree)C. Such high temperatures will be required for the new generation of gas turbines (inlet &amp;gt;750(degree)C) in Integrated Gasification Combined Cycle (IGCC) systems. The effect of pre-reduction on the performance of the sorbents as well as the rate of different reactions occurring in cyclic sulfidation/regeneration, were studied in a thermogravimetric analyzer (TGA). Sulfidation was conducted with and without H(sub 2) and H(sub 2)O, and with and without pre-reduction in H(sub 2) or H(sub 2)/H(sub 2)O. The results of these tests indicate that reduction and regeneration of both sorbents occurs rapidly. Sulfidation of CuCr(sub 2)O(sub 4), in H(sub 2)O-free and H(sub 2)-/H(sub 2)O-free gas indicates the possible sulfidation of both copper and chromium. Small quantities of SO(sub 2), were released during sulfidation suggesting the possible oxidation of H(sub 2)S by the sorbent. Regeneration of the CuCr(sub 2)O(sub 4) was complete while regeneration of the CuO-CeO(sub 2) indicated possible limited sulfate formation.","Development of novel copper-based sorbents for hot-gas cleanup. (Quarterly) technical report, September 1--November 30, 1993 Abs: Progress rept. red by Department of Energy, Washington, DC. jective of this investigation is to evaluate two novel copper-based sorbents, namely copper-chromium and copper-cerium, for their effectiveness in removing hydrogen sulfide from fuel gas in the temperature range of 650(degree) to 850(degree)C. Such high temperatures will be required for the new generation of gas turbines (inlet &amp;gt;750(degree)C) in Integrated Gasification Combined Cycle (IGCC) systems. The effect of pre-reduction on the performance of the sorbents as well as the rate of different reactions occurring in cyclic sulfidation/regeneration, were studied in a thermogravimetric analyzer (TGA). Sulfidation was conducted with and without H(sub 2) and H(sub 2)O, and with and without pre-reduction in H(sub 2) or H(sub 2)/H(sub 2)O. The results of these tests indicate that reduction and regeneration of both sorbents occurs rapidly. Sulfidation of CuCr(sub 2)O(sub 4), in H(sub 2)O-free and H(sub 2)-/H(sub 2)O-free gas indicates the possible sulfidation of both copper and chromium. Small quantities of SO(sub 2), were released during sulfidation suggesting the possible oxidation of H(sub 2)S by the sorbent. Regeneration of the CuCr(sub 2)O(sub 4) was complete while regeneration of the CuO-CeO(sub 2) indicated possible limited sulfate formation."
1510071,Hill et al. 1993,"Development of novel copper-based sorbents for hot-gas cleanup. Final technical report, 1 September 1992--31 August, 1993","Progress rept. red by Department of Energy, Washington, DC. jective of this investigation is to evaluate two novel copper-based sorbents, namely Cu-Cr and Cu-Ce, for their effectiveness in removing hydrogen sulfide from fuel gas in the temperature range of 650 to 850 C. Such high temperatures will be required for the new generation of gas turbines in Integrated Gasification Combined Cycle systems. Structural and kinetic studies were conducted on various compositions of the two Cu-based sorbents to determine the optimum sorbent composition. The effect to operating conditions on the performance of the sorbents along with the stability and regenerability of the selected sorbents in successive sulfidation/regeneration operation were determined. Overall, the CuO-lean binaries (with Cr(sub 2)O(sub 3) or CeO(sub 2)) may benefit the H(sub 2)S breakthrough levels. While this is at the expense of sulfur capacity for the Cu-Cr-O sorbents, it may not affect the capacity of the Cu-Ce-O sorbents. Parametric multicycle desulfurization tests were conducted in a bench-scale quartz reactor at one atmosphere using the CuCr(sub 2)O(sub 4) and CuO-CeO(sub 2) sorbents. The parameters studied included temperature, space velocity, and feed gas composition. Both sorbents were able to reduce the H(sub 2)S concentration of the reactor feed gas from 5,000 ppmv to less than 1 ppmv to 10 ppmv at 750 to 850 C. Both sorbents were found to consume H(sub 2) and produce SO(sub 2) during the initial stages of sulfidation. Analysis of partially sulfided samples identified predominantly Cu metal, the additive oxide and small amounts of oxidic copper. For the Cu-Cr-O sorbents, the latter is apparently sufficient to keep the H(sub 2)S pre-breakthrough levels as low as has been reported in this work. For the Cu-Ce-O sorbents, in which very little or no oxidic copper remained, the low H(sub 2)S levels may be due to the participation of CeO(sub 2), whose sulfidation is promoted by Cu. (ERA citation 19:011459)","Development of novel copper-based sorbents for hot-gas cleanup. Final technical report, 1 September 1992--31 August, 1993 Abs: Progress rept. red by Department of Energy, Washington, DC. jective of this investigation is to evaluate two novel copper-based sorbents, namely Cu-Cr and Cu-Ce, for their effectiveness in removing hydrogen sulfide from fuel gas in the temperature range of 650 to 850 C. Such high temperatures will be required for the new generation of gas turbines in Integrated Gasification Combined Cycle systems. Structural and kinetic studies were conducted on various compositions of the two Cu-based sorbents to determine the optimum sorbent composition. The effect to operating conditions on the performance of the sorbents along with the stability and regenerability of the selected sorbents in successive sulfidation/regeneration operation were determined. Overall, the CuO-lean binaries (with Cr(sub 2)O(sub 3) or CeO(sub 2)) may benefit the H(sub 2)S breakthrough levels. While this is at the expense of sulfur capacity for the Cu-Cr-O sorbents, it may not affect the capacity of the Cu-Ce-O sorbents. Parametric multicycle desulfurization tests were conducted in a bench-scale quartz reactor at one atmosphere using the CuCr(sub 2)O(sub 4) and CuO-CeO(sub 2) sorbents. The parameters studied included temperature, space velocity, and feed gas composition. Both sorbents were able to reduce the H(sub 2)S concentration of the reactor feed gas from 5,000 ppmv to less than 1 ppmv to 10 ppmv at 750 to 850 C. Both sorbents were found to consume H(sub 2) and produce SO(sub 2) during the initial stages of sulfidation. Analysis of partially sulfided samples identified predominantly Cu metal, the additive oxide and small amounts of oxidic copper. For the Cu-Cr-O sorbents, the latter is apparently sufficient to keep the H(sub 2)S pre-breakthrough levels as low as has been reported in this work. For the Cu-Ce-O sorbents, in which very little or no oxidic copper remained, the low H(sub 2)S levels may be due to the participation of CeO(sub 2), whose sulfidation is promoted by Cu. (ERA citation 19:011459)"
1510070,Macleod et al. 1994,Tomographic data developed using the ABEM RAMAC borehole radar system at the Mixed Waste Landfill Integrated Demonstration,"The ABEM RAMAC borehole radar system was run as part of the Mixed Waste Landfill Integrated Demonstration for Sandia National Laboratories at Kirtland AFB. Tomograms were created between three test boreholes-UCAP No. 1, UCAP No. 2, and UCAP No. 3. These tomograms clearly delineate areas of amplitude attenuation and residual time of arrival or slowness differences. Plots for slowness were made using both the maximum and minimum of the first arrival pulse. The data demonstrates that the ABEM RAMAC 60-MHz pulse sampling radar system can be used to collect usable data in a highly conductive environment.","Tomographic data developed using the ABEM RAMAC borehole radar system at the Mixed Waste Landfill Integrated Demonstration Abs: The ABEM RAMAC borehole radar system was run as part of the Mixed Waste Landfill Integrated Demonstration for Sandia National Laboratories at Kirtland AFB. Tomograms were created between three test boreholes-UCAP No. 1, UCAP No. 2, and UCAP No. 3. These tomograms clearly delineate areas of amplitude attenuation and residual time of arrival or slowness differences. Plots for slowness were made using both the maximum and minimum of the first arrival pulse. The data demonstrates that the ABEM RAMAC 60-MHz pulse sampling radar system can be used to collect usable data in a highly conductive environment."
1510069,Hasbrouck 1993,TTP AL921102: An integrated geophysics program for non-intrusive characterization of mixed-Waste landfill sites. Final report,"Progress rept. red by Department of Energy, Washington, DC. echnical Task conducted for the US Department of Energy Office of Technology Development demonstrates the effectiveness of integrating several surface geophysical techniques to nonintrusively characterize mixed-waste landfill sites. An integrated approach enables an area to be characterized faster and cheaper because repeated access is not necessary and offers data and interpretations not attainable by a single technique. Field demonstrations using the complex galvanic resistivity, spontaneous potential (SP), ground-penetrating radar (GPR), time-domain electromagnetic (TDEM), shear-wave (S-wave) seismic and compressional-wave (P-wave) seismic geophysical techniques were conducted at the Mixed-Waste Landfill Integrated Demonstration (MWLID) test site at the Sandia National Laboratories/New Mexico in Albuquerque. Data were acquired in two areas that have both known and unknown attributes. Although data from numerous profiles were analyzed, three lines were chosen as representative of the landfill site: Line 20E that crosses both the known Chromic Acid and Organics Pits, Line 60E that transectes an essentially barren area, and Line 125E located in an area with unknown subsurface conditions.","TTP AL921102: An integrated geophysics program for non-intrusive characterization of mixed-Waste landfill sites. Final report Abs: Progress rept. red by Department of Energy, Washington, DC. echnical Task conducted for the US Department of Energy Office of Technology Development demonstrates the effectiveness of integrating several surface geophysical techniques to nonintrusively characterize mixed-waste landfill sites. An integrated approach enables an area to be characterized faster and cheaper because repeated access is not necessary and offers data and interpretations not attainable by a single technique. Field demonstrations using the complex galvanic resistivity, spontaneous potential (SP), ground-penetrating radar (GPR), time-domain electromagnetic (TDEM), shear-wave (S-wave) seismic and compressional-wave (P-wave) seismic geophysical techniques were conducted at the Mixed-Waste Landfill Integrated Demonstration (MWLID) test site at the Sandia National Laboratories/New Mexico in Albuquerque. Data were acquired in two areas that have both known and unknown attributes. Although data from numerous profiles were analyzed, three lines were chosen as representative of the landfill site: Line 20E that crosses both the known Chromic Acid and Organics Pits, Line 60E that transectes an essentially barren area, and Line 125E located in an area with unknown subsurface conditions."
1510068,Abbasian et al. 1992,"Development of novel copper-based sorbents for hot-gas cleanup. Final technical report, September 1, 1991--August 31, 1992","Progress rept. red by Department of Energy, Washington, DC. jective of this investigation was to evaluate several novel copper-based binary oxides for their suitability as regenerable sorbents for hot gas cleanup application in the temperature range of 650(degree) to 850(degree)C. To achieve this objective, several novel binary oxides of copper were systematically evaluated and ranked in terms of their high-temperature stability against reduction to metal, sulfidation reactivity, and regenerability. The sorbents studied included oxides of chromium, cerium, aluminum, magnesium, manganese, titanium, iron, and silicon. The results of initial testing indicated that mixed binary oxides of copper with chromium (CuCr(sub 2)O(sub 4)) and cerium (CuO(circle dot)CeO(sub 2)) were the most promising sorbents for such high temperature gas cleanup applications. These two sorbents were further evaluated in cyclic sulfidation/regeneration tests in 10--15 cycles to determine the effect of operating conditions on their performance. The results of this investigation indicate that the two selected sorbents, copper-chromium and copper-cerium, are capable of removing H(sub 2)S from the hot fuel gas to very low levels (&amp;lt;10 ppmv) at temperatures as high as 850(degree)C with good sorbent regenerability in cyclic process. These sorbents should be further studied to achieve optimum sorbent composition for hot gas cleanup application.","Development of novel copper-based sorbents for hot-gas cleanup. Final technical report, September 1, 1991--August 31, 1992 Abs: Progress rept. red by Department of Energy, Washington, DC. jective of this investigation was to evaluate several novel copper-based binary oxides for their suitability as regenerable sorbents for hot gas cleanup application in the temperature range of 650(degree) to 850(degree)C. To achieve this objective, several novel binary oxides of copper were systematically evaluated and ranked in terms of their high-temperature stability against reduction to metal, sulfidation reactivity, and regenerability. The sorbents studied included oxides of chromium, cerium, aluminum, magnesium, manganese, titanium, iron, and silicon. The results of initial testing indicated that mixed binary oxides of copper with chromium (CuCr(sub 2)O(sub 4)) and cerium (CuO(circle dot)CeO(sub 2)) were the most promising sorbents for such high temperature gas cleanup applications. These two sorbents were further evaluated in cyclic sulfidation/regeneration tests in 10--15 cycles to determine the effect of operating conditions on their performance. The results of this investigation indicate that the two selected sorbents, copper-chromium and copper-cerium, are capable of removing H(sub 2)S from the hot fuel gas to very low levels (&amp;lt;10 ppmv) at temperatures as high as 850(degree)C with good sorbent regenerability in cyclic process. These sorbents should be further studied to achieve optimum sorbent composition for hot gas cleanup application."
1510067,Johnson 1993,"Adaptive sampling strategy support for the unlined chromic acid pit, chemical waste landfill, Sandia National Laboratories, Albuquerque, New Mexico","Sponsored by Department of Energy, Washington, DC. ve sampling programs offer substantial savings in time and money when assessing hazardous waste sites. Key to some of these savings is the ability to adapt a sampling program to the real-time data generated by an adaptive sampling program. This paper presents a two-prong approach to supporting adaptive sampling programs: a specialized object-oriented database/geographical information system (SitePlanner(trademark) ) for data fusion, management, and display and combined Bayesian/geostatistical methods (PLUME) for contamination-extent estimation and sample location selection. This approach is applied in a retrospective study of a subsurface chromium plume at Sandia National Laboratories' chemical waste landfill. Retrospective analyses suggest the potential for characterization cost savings on the order of 60% through a reduction in the number of sampling programs, total number of soil boreholes, and number of samples analyzed from each borehole.","Adaptive sampling strategy support for the unlined chromic acid pit, chemical waste landfill, Sandia National Laboratories, Albuquerque, New Mexico Abs: Sponsored by Department of Energy, Washington, DC. ve sampling programs offer substantial savings in time and money when assessing hazardous waste sites. Key to some of these savings is the ability to adapt a sampling program to the real-time data generated by an adaptive sampling program. This paper presents a two-prong approach to supporting adaptive sampling programs: a specialized object-oriented database/geographical information system (SitePlanner(trademark) ) for data fusion, management, and display and combined Bayesian/geostatistical methods (PLUME) for contamination-extent estimation and sample location selection. This approach is applied in a retrospective study of a subsurface chromium plume at Sandia National Laboratories' chemical waste landfill. Retrospective analyses suggest the potential for characterization cost savings on the order of 60% through a reduction in the number of sampling programs, total number of soil boreholes, and number of samples analyzed from each borehole."
1510066,Thorton and  Trader 1993,Laboratory evaluation of the in situ chemical treatment approach to soil and groundwater remediation,"Department of Energy environmental remediation conference, Augusta, GA (United States), 24-28 Oct 1993. Sponsored by Department of Energy, Washington, DC. s of initial proof of principle laboratory testing activities successfully demonstrated the viability of the in situ chemical treatment approach for remediation of soil and groundwater contaminated by hexavalent chromium. Testing activities currently in progress further indicate that soils contaminated with hexavalent chromium and uranium at concentrations of several hundred parts per million can be successfully treated with 100 ppM hydrogen sulfide gas mixtures. Greater than 90% immobilization of hexavalent chromium and 50% immobilization of uranium have been achieved in these tests after a treatment period of one day. Activities associated with further development and implementation of the in situ chemical treatment approach include conducting additional bench scale tests with contaminated geomedia, and undertaking scale-up laboratory tests and a field demonstration. This report discusses the testing and further development of this process.","Laboratory evaluation of the in situ chemical treatment approach to soil and groundwater remediation Abs: Department of Energy environmental remediation conference, Augusta, GA (United States), 24-28 Oct 1993. Sponsored by Department of Energy, Washington, DC. s of initial proof of principle laboratory testing activities successfully demonstrated the viability of the in situ chemical treatment approach for remediation of soil and groundwater contaminated by hexavalent chromium. Testing activities currently in progress further indicate that soils contaminated with hexavalent chromium and uranium at concentrations of several hundred parts per million can be successfully treated with 100 ppM hydrogen sulfide gas mixtures. Greater than 90% immobilization of hexavalent chromium and 50% immobilization of uranium have been achieved in these tests after a treatment period of one day. Activities associated with further development and implementation of the in situ chemical treatment approach include conducting additional bench scale tests with contaminated geomedia, and undertaking scale-up laboratory tests and a field demonstration. This report discusses the testing and further development of this process."
1510065,Granstaff and  Chambers 1993,Application of surface complexation modeling to the understanding of transportation cask weeping,"Fall meeting of the Materials Research Society (MRS), Boston, MA (United States), 29 Nov - 3 Dec 1993. Sponsored by Department of Energy, Washington, DC. application for surface complexation modeling is described. These models, which describe chemical equilibria among aqueous and adsorbed species, have typically been used for predicting groundwater transport of contaminants by modeling the natural adsorbents as various metal oxides. We have shown that this type of modeling can also be used to explain stainless steel surface contamination and decontamination mechanisms. Stainless steel transportation casks that are submerged in a spent fuel storage pool at nuclear power stations, can become contaminated with radionuclides such as (sup 137)CS, (sup 134)Cs, and (sup 60)Co. Subsequent release or desorption of these contaminants under varying environmental conditions occasionally results in the phenomenon known as ''cask weeping.'' We have postulated that contaminants in the storage pool adsorb onto the hydrous metal oxide surface of the passivated stainless steel and are subsequently released during transportation, due to varying environmental factors, such as humidity, road salt, dirt, and acid rain. It is well known that 304 stainless steel has a chromium enriched passive surface layer; thus its adsorption behavior should be similar to that of chromium oxide. Presented here are adsorption data for Co(sup +2) on Cr(sup 2)O(sup 3) which simulate the stainless steel surface contamination. These data are interpreted using electrostatic surface complexation models. The FITEQL computer program was used to obtain the electrostatic model constants from the experimental data. Because the concentrations of contaminants in the storage pool are too low to be measured accurately by conventional chemical analysis techniques, MINTEQA2 can be used, with the fitted constants, to extrapolate the equilibria to the low concentrations representative of storage pool water.","Application of surface complexation modeling to the understanding of transportation cask weeping Abs: Fall meeting of the Materials Research Society (MRS), Boston, MA (United States), 29 Nov - 3 Dec 1993. Sponsored by Department of Energy, Washington, DC. application for surface complexation modeling is described. These models, which describe chemical equilibria among aqueous and adsorbed species, have typically been used for predicting groundwater transport of contaminants by modeling the natural adsorbents as various metal oxides. We have shown that this type of modeling can also be used to explain stainless steel surface contamination and decontamination mechanisms. Stainless steel transportation casks that are submerged in a spent fuel storage pool at nuclear power stations, can become contaminated with radionuclides such as (sup 137)CS, (sup 134)Cs, and (sup 60)Co. Subsequent release or desorption of these contaminants under varying environmental conditions occasionally results in the phenomenon known as ''cask weeping.'' We have postulated that contaminants in the storage pool adsorb onto the hydrous metal oxide surface of the passivated stainless steel and are subsequently released during transportation, due to varying environmental factors, such as humidity, road salt, dirt, and acid rain. It is well known that 304 stainless steel has a chromium enriched passive surface layer; thus its adsorption behavior should be similar to that of chromium oxide. Presented here are adsorption data for Co(sup +2) on Cr(sup 2)O(sup 3) which simulate the stainless steel surface contamination. These data are interpreted using electrostatic surface complexation models. The FITEQL computer program was used to obtain the electrostatic model constants from the experimental data. Because the concentrations of contaminants in the storage pool are too low to be measured accurately by conventional chemical analysis techniques, MINTEQA2 can be used, with the fitted constants, to extrapolate the equilibria to the low concentrations representative of storage pool water."
1510064,Krause and  Tarman 1993,Preliminary results from the investigation of thermal effects in electrokinetics soil remediation,"Annual American Chemical Society (ACS) Industrial and Engineering Chemistry (I&amp;EC) Division special symposium on emerging technologies for hazardous waste management (5th), Atlanta, GA (United States), 27-29 Sep 1993. Sponsored by Department of Energy, Washington, DC. okinetics is an emerging soil remediation technology. Contaminants are extracted from the soil as a result of a complex set of phenomena that occur when an electric gradient is imposed across a soil-water system. The primary phenomena include electroosmosis, electromigration, and electrophoresis. Secondary phenomena, such as changes in solubility or speciation of various chemical components, may occur as a result of electrically induced changes in the chemical environment of the system. Numerous factors, such as temperature, may affect each of these phenomena and, consequently, the overall process efficiency. We have begun an investigation of thermal effects in the extraction of potassium dichromate from kaolinite soils under conditions of constant saturation and dewatering. Preliminary results suggest that increasing the soil temperature from 21 to 55(degrees)C may decrease the processing time under saturated conditions. However, increasing the soil temperature under dewatering, conditions causes soil cracking, which reduces the overall process efficiency.","Preliminary results from the investigation of thermal effects in electrokinetics soil remediation Abs: Annual American Chemical Society (ACS) Industrial and Engineering Chemistry (I&amp;EC) Division special symposium on emerging technologies for hazardous waste management (5th), Atlanta, GA (United States), 27-29 Sep 1993. Sponsored by Department of Energy, Washington, DC. okinetics is an emerging soil remediation technology. Contaminants are extracted from the soil as a result of a complex set of phenomena that occur when an electric gradient is imposed across a soil-water system. The primary phenomena include electroosmosis, electromigration, and electrophoresis. Secondary phenomena, such as changes in solubility or speciation of various chemical components, may occur as a result of electrically induced changes in the chemical environment of the system. Numerous factors, such as temperature, may affect each of these phenomena and, consequently, the overall process efficiency. We have begun an investigation of thermal effects in the extraction of potassium dichromate from kaolinite soils under conditions of constant saturation and dewatering. Preliminary results suggest that increasing the soil temperature from 21 to 55(degrees)C may decrease the processing time under saturated conditions. However, increasing the soil temperature under dewatering, conditions causes soil cracking, which reduces the overall process efficiency."
1510063,Hill et al. 1993,"Development of novel copper-based sorbents for hot-gas cleanup. (Quarterly) technical report, March 1, 1993--May 31, 1993","Progress rept. red by Department of Energy, Washington, DC. jective of this investigation is to evaluate two novel copper-based sorbents (i.e. copper-chromium and copper-cerium) for their effectiveness in removing hydrogen sulfide from fuel gas in the temperature range of 650(degrees) to 850(degrees)C. In this program, structural and kinetic studies are conducted on various compositions of the two selected copper-based sorbents to determine the optimum sorbent composition. The effect of operating conditions on the performance of the sorbents alone with the stability and regenerability of the selected sorbents in successive sulfidation/regeneration operation are determined. Parametric multicycle desulfurization tests were conducted this quarter in a bench-scale (5-cm-diameter) quartz reactor at one atmosphere using the CuCr(sub 2)O(sub 4) and CuO/CeO(sub 2) sorbents. The parameters studied included temperature, space velocity, and feed gas composition. Both sorbents were able to reduce the H(sub 2)S concentration of the reactor feed gas to &amp;lt;10 ppM under all conditions tested. The apparent reactivity of the CuO/CeO(sub 2) sorbent was lower after the first cycle which may be attributed to incomplete regeneration caused by sulfate formation.","Development of novel copper-based sorbents for hot-gas cleanup. (Quarterly) technical report, March 1, 1993--May 31, 1993 Abs: Progress rept. red by Department of Energy, Washington, DC. jective of this investigation is to evaluate two novel copper-based sorbents (i.e. copper-chromium and copper-cerium) for their effectiveness in removing hydrogen sulfide from fuel gas in the temperature range of 650(degrees) to 850(degrees)C. In this program, structural and kinetic studies are conducted on various compositions of the two selected copper-based sorbents to determine the optimum sorbent composition. The effect of operating conditions on the performance of the sorbents alone with the stability and regenerability of the selected sorbents in successive sulfidation/regeneration operation are determined. Parametric multicycle desulfurization tests were conducted this quarter in a bench-scale (5-cm-diameter) quartz reactor at one atmosphere using the CuCr(sub 2)O(sub 4) and CuO/CeO(sub 2) sorbents. The parameters studied included temperature, space velocity, and feed gas composition. Both sorbents were able to reduce the H(sub 2)S concentration of the reactor feed gas to &amp;lt;10 ppM under all conditions tested. The apparent reactivity of the CuO/CeO(sub 2) sorbent was lower after the first cycle which may be attributed to incomplete regeneration caused by sulfate formation."
1510062,Hill et al. 1993,"Development of novel copper-based sorbents for hot gas cleanup. Technical report, December 1, 1992--February 28, 1993","Sponsored by Department of Energy, Washington, DC. jective of this investigation is to evaluate two novel copper-based sorbents (i.e. copper-chromium and copper-cerium) for their effectiveness in removing hydrogen sulfide from fuel gas in the temperature range of 650(degree) to 850(degree)C. New sorbent compositions from the selected Cu-Cr-O and Cu-Ce-O binary oxides were prepared and characterized by BET N(sub 2)-desorption surface area measurement following various calcination/time-temperature exposures. The general trends reported last quarter (on 11 different compositions) were validated this quarter in that both binary oxides lose surface area as the amount of CuO is increased. Time-resolved sulfidation tests were conducted at 850(degree)C using the equimolar CuO.Cr(sub 2)O(sub 3) composition. The two selected binary oxides prepared in larger qauntities (for testing in a two-inch reactor) have physical properties typical of the sorbents prepared in past programs. Two multicycle desulfurization tests, conducted this quarter on the Cu-Ce-O sorbent at 850(degree)C, using a feed gas containing 5000 ppm H(sub 2)S, 10 vol % H(sub 2) and 10 vol % H(sub 2)O at a space velocity (STP) of 2000 h(sup (minus)1), demonstrated high sulfur removal efficiency for the first one or two cycles, and a significant reduction in efficiency in the following cycles.","Development of novel copper-based sorbents for hot gas cleanup. Technical report, December 1, 1992--February 28, 1993 Abs: Sponsored by Department of Energy, Washington, DC. jective of this investigation is to evaluate two novel copper-based sorbents (i.e. copper-chromium and copper-cerium) for their effectiveness in removing hydrogen sulfide from fuel gas in the temperature range of 650(degree) to 850(degree)C. New sorbent compositions from the selected Cu-Cr-O and Cu-Ce-O binary oxides were prepared and characterized by BET N(sub 2)-desorption surface area measurement following various calcination/time-temperature exposures. The general trends reported last quarter (on 11 different compositions) were validated this quarter in that both binary oxides lose surface area as the amount of CuO is increased. Time-resolved sulfidation tests were conducted at 850(degree)C using the equimolar CuO.Cr(sub 2)O(sub 3) composition. The two selected binary oxides prepared in larger qauntities (for testing in a two-inch reactor) have physical properties typical of the sorbents prepared in past programs. Two multicycle desulfurization tests, conducted this quarter on the Cu-Ce-O sorbent at 850(degree)C, using a feed gas containing 5000 ppm H(sub 2)S, 10 vol % H(sub 2) and 10 vol % H(sub 2)O at a space velocity (STP) of 2000 h(sup (minus)1), demonstrated high sulfur removal efficiency for the first one or two cycles, and a significant reduction in efficiency in the following cycles."
1510061,Serne et al. 1993,Leach testing of in situ stabilization grouts containing additives to sequester contaminants,"Sponsored by Department of Energy, Washington, DC. ocument discusses laboratory testing performed by Pacific Northwest Laboratory (PNL) for Westinghouse Hanford Company (WHC) of special grout formulations that incorporate specific sequestering agents to help improve the ability of the cement to resist contaminant leaching. To enhance the sequestering of contaminants we chose five additives to introduce (singly) to the control cement. The additives were Florida pebble phosphate, clinoptilolite (a natural zeolite), ferrous sulfide (a reductant), a mixed bed organic ion exchange resin and a proprietary anion-adsorbing mixed metal oxide. These additives were added one per test to the standard formulation and used to encapsulate a diluted high-salt alkaline liquid waste that is produced after various processes to remove uranium and plutonium from spent nuclear fuel. This report documents the testing of these additives.","Leach testing of in situ stabilization grouts containing additives to sequester contaminants Abs: Sponsored by Department of Energy, Washington, DC. ocument discusses laboratory testing performed by Pacific Northwest Laboratory (PNL) for Westinghouse Hanford Company (WHC) of special grout formulations that incorporate specific sequestering agents to help improve the ability of the cement to resist contaminant leaching. To enhance the sequestering of contaminants we chose five additives to introduce (singly) to the control cement. The additives were Florida pebble phosphate, clinoptilolite (a natural zeolite), ferrous sulfide (a reductant), a mixed bed organic ion exchange resin and a proprietary anion-adsorbing mixed metal oxide. These additives were added one per test to the standard formulation and used to encapsulate a diluted high-salt alkaline liquid waste that is produced after various processes to remove uranium and plutonium from spent nuclear fuel. This report documents the testing of these additives."
1510060,Semones et al. 1993,Development of the fluidized bed thermal treatment process for treating mixed waste,"EG&amp;G GOCO environmental conference (2nd), Idaho Falls, ID (United States), 12-14 May 1993. Sponsored by Department of Energy, Washington, DC. dized bed system is being developed at Rocky Flats for the treatment of mixed waste (a mixture of radioactive and chemically hazardous waste). The current program builds on experience gained in the 1970's and 1980's in tests with bench-scale, pilot-scale, and demonstration-scale fluidized bed systems. The system operates at low temperatures ((approx) 525--600(degree)C) which eliminates many of the disadvantages associated with high temperature thermal treatment processes. The process has shown the ability to destroy polychlorinated biphenyls (PCB's) with 99.9999% (''six-nines'') destruction efficiency in tests monitored by the Environmental Protection Agency (EPA). The bed makes use of in situ neutralization of acidic off-gases by incorporating sodium carbonate (Na(sub 2)CO(sub 3)) in the bed media. This eliminates using wet scrubbers to treat the off-gas; these produce a high volume of secondary waste. Once in operation, it is expected that the fluidized bed process will yield up to a 40:1 reduction in the volume of the waste.","Development of the fluidized bed thermal treatment process for treating mixed waste Abs: EG&amp;G GOCO environmental conference (2nd), Idaho Falls, ID (United States), 12-14 May 1993. Sponsored by Department of Energy, Washington, DC. dized bed system is being developed at Rocky Flats for the treatment of mixed waste (a mixture of radioactive and chemically hazardous waste). The current program builds on experience gained in the 1970's and 1980's in tests with bench-scale, pilot-scale, and demonstration-scale fluidized bed systems. The system operates at low temperatures ((approx) 525--600(degree)C) which eliminates many of the disadvantages associated with high temperature thermal treatment processes. The process has shown the ability to destroy polychlorinated biphenyls (PCB's) with 99.9999% (''six-nines'') destruction efficiency in tests monitored by the Environmental Protection Agency (EPA). The bed makes use of in situ neutralization of acidic off-gases by incorporating sodium carbonate (Na(sub 2)CO(sub 3)) in the bed media. This eliminates using wet scrubbers to treat the off-gas; these produce a high volume of secondary waste. Once in operation, it is expected that the fluidized bed process will yield up to a 40:1 reduction in the volume of the waste."
1510059,Dini and  Steffani 1992,Electroplating waste minimization at Lawrence Livermore National Laboratory,"Spectrum '92: nuclear and hazardous waste management international topical meeting, Boise, ID (United States), 23-27 Aug 1992. Sponsored by Department of Energy, Washington, DC. aper describes efforts on waste minimization in the electroplating facility at Lawrence Livermore National Laboratory (LLNL). Issues that are covered include: elimination of cadmium plating, copper cyanide plating, hexavalent chromium plating and vapor degreasing, segregation of cyanide solutions, changing rinsing practices, recycling of rinse water, changing cleaning of aluminum parts and rejuvenation of gold plating solutions. Discussion is also presented on other issues currently being worked and these include: combining electroplating and physical vapor deposition, elimination of all cyanide plating processes, and recycling of electroless nickel and spent acid solutions.","Electroplating waste minimization at Lawrence Livermore National Laboratory Abs: Spectrum '92: nuclear and hazardous waste management international topical meeting, Boise, ID (United States), 23-27 Aug 1992. Sponsored by Department of Energy, Washington, DC. aper describes efforts on waste minimization in the electroplating facility at Lawrence Livermore National Laboratory (LLNL). Issues that are covered include: elimination of cadmium plating, copper cyanide plating, hexavalent chromium plating and vapor degreasing, segregation of cyanide solutions, changing rinsing practices, recycling of rinse water, changing cleaning of aluminum parts and rejuvenation of gold plating solutions. Discussion is also presented on other issues currently being worked and these include: combining electroplating and physical vapor deposition, elimination of all cyanide plating processes, and recycling of electroless nickel and spent acid solutions."
1510058,Borns et al. 1992,Cross borehole electromagnetic imaging of chemical and mixed waste landfills,"SAGEEP '93: symposium on the application of geophysics to environmental and engineering problems, San Diego, CA (United States), 18-21 Apr 1993. Sponsored by Department of Energy, Washington, DC. xed Waste Landfill Integrated Demonstration (MWLID) is testing noninvasive site characterization methods at several locations, including the Chemical Waste Landfill (CWL) at Sandia National Laboratories. The CWL comprises shallow, unlined pits that were used for the disposal of acids, oils, solvents, and inorganic compounds from 1962 until the CWL was closed in 1985. The soils of the landfills are alluvial, predominantly sand, gravels and cobbles with small quantities of silts and clays. The focus of this study is an unlined chromic acid pit (UCAP). The UCAP pit is rectangular (approximately 4 (times) 10 m), which reportedly received unknown volumes of chromium in the form of chromic acid (liquid) and other hazardous materials. At this location, we have demonstrated a continuous waveform (CW) system for site characterization. During this year, we will also utilize a crossborehole pulsed radar system. Both methods are sensitive to variations in either electrical conductivity or dielectric constant in the soils or host rock at a waste site. These earth properties are some of the most responsive geophysical indicators of metallic, acidic and water-based subsurface contaminants.","Cross borehole electromagnetic imaging of chemical and mixed waste landfills Abs: SAGEEP '93: symposium on the application of geophysics to environmental and engineering problems, San Diego, CA (United States), 18-21 Apr 1993. Sponsored by Department of Energy, Washington, DC. xed Waste Landfill Integrated Demonstration (MWLID) is testing noninvasive site characterization methods at several locations, including the Chemical Waste Landfill (CWL) at Sandia National Laboratories. The CWL comprises shallow, unlined pits that were used for the disposal of acids, oils, solvents, and inorganic compounds from 1962 until the CWL was closed in 1985. The soils of the landfills are alluvial, predominantly sand, gravels and cobbles with small quantities of silts and clays. The focus of this study is an unlined chromic acid pit (UCAP). The UCAP pit is rectangular (approximately 4 (times) 10 m), which reportedly received unknown volumes of chromium in the form of chromic acid (liquid) and other hazardous materials. At this location, we have demonstrated a continuous waveform (CW) system for site characterization. During this year, we will also utilize a crossborehole pulsed radar system. Both methods are sensitive to variations in either electrical conductivity or dielectric constant in the soils or host rock at a waste site. These earth properties are some of the most responsive geophysical indicators of metallic, acidic and water-based subsurface contaminants."
1510057,Hasbrouck 1992,TTP AL921102: An integrated geophysics program for non-intrusive characterization of mixed-waste landfill sites. FY 1992 year-end progress report: Volume 1,"Sponsored by Department of Energy, Washington, DC. uclear Geotech, Inc. (Geotech), operating contractor for the US Department of Energy Grand Junction Projects Office, is conducting the Integrated Geophysics Program for Non-Intrusive Characterization of Mixed-Waste Landfill Sites (Technical Task Plan (TTP) AL921102). The TTP is part of the Mixed-Waste Landfill Integrated Demonstration (MWLID). The objective of this task was to demonstrate that an integrated program of surface geophysics can be used to effectively and nonintrusively characterize n-mixed-waste landfill sites. To accomplish this objective, integrated field demonstrations were conducted over two previously identified areas of interest (designated Areas A and B) within the MWLID test site at the Chemical Waste Landfill (CWL), Technical Area 3, at the Sandia National Laboratories, Albuquerque, New Mexico (Figures 1 and 2). Area A was centered roughly around the Chromic Acid and Organics Pits in the southeast-central portion of the landfill and Area B was centered around the ''60's Pits'' area in the northeast-central portion of the landfill. Pit locations were known in Area A and suspected in Area B. This progress report describes the geophysical surveys conducted by Geotech and presents preliminary displays and analyses. Volume 2 of this report contains the raw data for all the surveys conducted by Geotech for this TTP.","TTP AL921102: An integrated geophysics program for non-intrusive characterization of mixed-waste landfill sites. FY 1992 year-end progress report: Volume 1 Abs: Sponsored by Department of Energy, Washington, DC. uclear Geotech, Inc. (Geotech), operating contractor for the US Department of Energy Grand Junction Projects Office, is conducting the Integrated Geophysics Program for Non-Intrusive Characterization of Mixed-Waste Landfill Sites (Technical Task Plan (TTP) AL921102). The TTP is part of the Mixed-Waste Landfill Integrated Demonstration (MWLID). The objective of this task was to demonstrate that an integrated program of surface geophysics can be used to effectively and nonintrusively characterize n-mixed-waste landfill sites. To accomplish this objective, integrated field demonstrations were conducted over two previously identified areas of interest (designated Areas A and B) within the MWLID test site at the Chemical Waste Landfill (CWL), Technical Area 3, at the Sandia National Laboratories, Albuquerque, New Mexico (Figures 1 and 2). Area A was centered roughly around the Chromic Acid and Organics Pits in the southeast-central portion of the landfill and Area B was centered around the ''60's Pits'' area in the northeast-central portion of the landfill. Pit locations were known in Area A and suspected in Area B. This progress report describes the geophysical surveys conducted by Geotech and presents preliminary displays and analyses. Volume 2 of this report contains the raw data for all the surveys conducted by Geotech for this TTP."
1510055,Evans et al. 1992,Hanford Site ground-water monitoring for 1991,"Sponsored by Department of Energy, Washington, DC. cific Northwest Laboratory (PNL) monitors the distribution of radionuclides and other hazardous materials in ground water at the Hanford Site for the US Department of Energy (DOE). This work is performed through the Ground-Water Surveillance Project and is designed to meet the requirements of DOE Order 5400.1 that apply to environmental surveillance and ground-water monitoring (DOE 1988). This annual report discusses results of ground-water monitoring at the Hanford Site during 1991. In addition to the general discussion, the following topics are discussed in detail: (1) carbon tetrachloride in the 200-West Area; (2) cyanide in and north of the 200-East and the 200-West areas; (3) hexavalent chromium contamination in the 100, 200, and 600 areas; (4) trichloroethylene in the vicinity of the Solid Waste Landfill, 100-F Area, and 300 Area; (5) nitrate across the Site; (6) tritium across the Site; and (7) other radionuclide contamination throughout the Site, including gross alpha, gross beta, cobalt-60, strontium-90, technetium-99, iodine-129, cesium-137, uranium, and plutonium.","Hanford Site ground-water monitoring for 1991 Abs: Sponsored by Department of Energy, Washington, DC. cific Northwest Laboratory (PNL) monitors the distribution of radionuclides and other hazardous materials in ground water at the Hanford Site for the US Department of Energy (DOE). This work is performed through the Ground-Water Surveillance Project and is designed to meet the requirements of DOE Order 5400.1 that apply to environmental surveillance and ground-water monitoring (DOE 1988). This annual report discusses results of ground-water monitoring at the Hanford Site during 1991. In addition to the general discussion, the following topics are discussed in detail: (1) carbon tetrachloride in the 200-West Area; (2) cyanide in and north of the 200-East and the 200-West areas; (3) hexavalent chromium contamination in the 100, 200, and 600 areas; (4) trichloroethylene in the vicinity of the Solid Waste Landfill, 100-F Area, and 300 Area; (5) nitrate across the Site; (6) tritium across the Site; and (7) other radionuclide contamination throughout the Site, including gross alpha, gross beta, cobalt-60, strontium-90, technetium-99, iodine-129, cesium-137, uranium, and plutonium."
1510053,Oh et al. 1991,Decontamination and restoration technology development,In Korean. tudy is to develop a chemical decontamination technology applicable in a high radiation field such as spent fuel decontamination. A new decontamination formulation was developed in this study by adding ascorbic acid into the existing KAERI chemicals mainly consisting of EDTA and citric acid showed remarkable improvement in dissolution rate of nickel ferrite particles which were hard to be removed by conventional chemical decontamination reagents. The decontamination process development using the reagent was also carried out in this study. The hot loop decontamination tests using the specimens of Inconel-600 and SUS-304 contacted with the pressure boundary of primary coolant in Kori Unit 1 showed high decontamination factors which is as good as or even better than those of foreign processes such as LOMI and CAN-DECON. The decontamination test using spent fuel rod in Kori Unit 1 resulted in almost complete removal of crud from the rod surface. The material damages measured by corrosion surveilance specimen were very small and no localized corrosion were detected. The catalytic wet oxidation behaviors were also studied to decompose decontamination wastes. The Fe(II) catalyst was found to be effective. (Author). (Atomindex citation 23:014176),Decontamination and restoration technology development Abs: In Korean. tudy is to develop a chemical decontamination technology applicable in a high radiation field such as spent fuel decontamination. A new decontamination formulation was developed in this study by adding ascorbic acid into the existing KAERI chemicals mainly consisting of EDTA and citric acid showed remarkable improvement in dissolution rate of nickel ferrite particles which were hard to be removed by conventional chemical decontamination reagents. The decontamination process development using the reagent was also carried out in this study. The hot loop decontamination tests using the specimens of Inconel-600 and SUS-304 contacted with the pressure boundary of primary coolant in Kori Unit 1 showed high decontamination factors which is as good as or even better than those of foreign processes such as LOMI and CAN-DECON. The decontamination test using spent fuel rod in Kori Unit 1 resulted in almost complete removal of crud from the rod surface. The material damages measured by corrosion surveilance specimen were very small and no localized corrosion were detected. The catalytic wet oxidation behaviors were also studied to decompose decontamination wastes. The Fe(II) catalyst was found to be effective. (Author). (Atomindex citation 23:014176)
1510052,Dini and  Steffani 1991,Waste Minimization Plans and activities in the MFD Plating Shop,"Sponsored by Department of Energy, Washington, DC. ating Shop (Building 322), provides processes such as electroplating, electroless plating, anodizing, cleaning, etching, electroforming and chemical milling. We in MFD are committed to an active program on waste minimization, and the purpose of this document is to outline the plan of action. Our short range minimization goals are threefold: (1) Reduce our major waste stream by 90%, (2) Minimize discharge of rinse water to sewer system, and (3) Eliminate vapor degreasing in the shop. The intermediate goals consist of characterizing the waste streams and evaluating recovery processes. To do this, we first need to have the distillation unit operational and time to determine its effectiveness. If it proves to be as effective as we anticipate, we will perhaps purchase a second unit. Regardless, the streams that we can identify include: nickel, copper, rinses, acids, alkalies, electropolish and miscellaneous. Our goal is to utilize electrolytic processes to recover metals such as nickel and copper and processes such as ion exchange for some of the other streams. We intend to evaluate the full gamut of recycling processes available for these streams. We anticipate completing this phase of the minimization program by January 1993. The long range goal is zero discharge or since this could prove extremely difficult, development of processes that will allow us to produce a sludge cake that could be handled by our Hazardous Waste Management Group.","Waste Minimization Plans and activities in the MFD Plating Shop Abs: Sponsored by Department of Energy, Washington, DC. ating Shop (Building 322), provides processes such as electroplating, electroless plating, anodizing, cleaning, etching, electroforming and chemical milling. We in MFD are committed to an active program on waste minimization, and the purpose of this document is to outline the plan of action. Our short range minimization goals are threefold: (1) Reduce our major waste stream by 90%, (2) Minimize discharge of rinse water to sewer system, and (3) Eliminate vapor degreasing in the shop. The intermediate goals consist of characterizing the waste streams and evaluating recovery processes. To do this, we first need to have the distillation unit operational and time to determine its effectiveness. If it proves to be as effective as we anticipate, we will perhaps purchase a second unit. Regardless, the streams that we can identify include: nickel, copper, rinses, acids, alkalies, electropolish and miscellaneous. Our goal is to utilize electrolytic processes to recover metals such as nickel and copper and processes such as ion exchange for some of the other streams. We intend to evaluate the full gamut of recycling processes available for these streams. We anticipate completing this phase of the minimization program by January 1993. The long range goal is zero discharge or since this could prove extremely difficult, development of processes that will allow us to produce a sludge cake that could be handled by our Hazardous Waste Management Group."
1510051,Dini and  Steffani 1991,Waste minimization in a non-production oriented metal finishing operation,"American Electroplates Societies Foundation (AESF)/EPA conference on environmental control (13th), Orlando, FL (United States), 27-31 Jan 1992. Sponsored by Department of Energy, Washington, DC. aper provides information on activities undertaken in a non- production oriented metal finishing operation to minimize waste and conserve resources. The facility is a 6000 sq foot shop that typically only deals with prototype parts. Utilizing a plan that includes employee awareness, common sense and existing technology, a noticeable reduction in waste volume has been obtained. Initiatives that are covered include: segregation of cyanide plating solutions, elimination of copper cyanide plating, elimination of hexavalent chromium plating, elimination of vapor degreasing, changing of rinsing practices, and changing a process for cleaning of aluminum parts. Some discussion is also presented on the effectiveness of combining the technologies of physical vapor deposition and electrodeposition to help minimize waste. Plans for additional initiatives including water recycling, elimination of cyanide plating and substitution of electrodeposition for electroless deposition of Ni-P alloys are also covered.","Waste minimization in a non-production oriented metal finishing operation Abs: American Electroplates Societies Foundation (AESF)/EPA conference on environmental control (13th), Orlando, FL (United States), 27-31 Jan 1992. Sponsored by Department of Energy, Washington, DC. aper provides information on activities undertaken in a non- production oriented metal finishing operation to minimize waste and conserve resources. The facility is a 6000 sq foot shop that typically only deals with prototype parts. Utilizing a plan that includes employee awareness, common sense and existing technology, a noticeable reduction in waste volume has been obtained. Initiatives that are covered include: segregation of cyanide plating solutions, elimination of copper cyanide plating, elimination of hexavalent chromium plating, elimination of vapor degreasing, changing of rinsing practices, and changing a process for cleaning of aluminum parts. Some discussion is also presented on the effectiveness of combining the technologies of physical vapor deposition and electrodeposition to help minimize waste. Plans for additional initiatives including water recycling, elimination of cyanide plating and substitution of electrodeposition for electroless deposition of Ni-P alloys are also covered."
1510050,Davenport et al. 1991,XANES studies of chromate replacements in oxide films on aluminum,"Meeting of the Electrochemical Society (180th), Phoenix, AZ (United States), 13-18 Oct 1991. Sponsored by Department of Energy, Washington, DC. emistry of conversion coatings on aluminum containing chromate and non-toxic chromate replacements has been investigated using XANES. Chromate conversion coatings contain 20% 6-valent chromium which is gradually lost on immersion in a corrosive environment. The most promising alternative coatings are those based on phosphotungstate. The chemistry of these and coatings containing Mo, V, and Mn are discussed.","XANES studies of chromate replacements in oxide films on aluminum Abs: Meeting of the Electrochemical Society (180th), Phoenix, AZ (United States), 13-18 Oct 1991. Sponsored by Department of Energy, Washington, DC. emistry of conversion coatings on aluminum containing chromate and non-toxic chromate replacements has been investigated using XANES. Chromate conversion coatings contain 20% 6-valent chromium which is gradually lost on immersion in a corrosive environment. The most promising alternative coatings are those based on phosphotungstate. The chemistry of these and coatings containing Mo, V, and Mn are discussed."
1510049,Hou et al. 1991,Distribution of ion-implanted yttrium in Cr2O3 scale and in the underlying Ni-25 wt % Cr alloy,"International conference on surface modification of metals by ion beams (SMMIB-7) (7th), Washington, DC (United States), 15-19 Jul 1991. Sponsored by Department of Energy, Washington, DC. tation of yttrium and other reactive metals has been known to show significant effects on the oxidation behavior of Cr(sub 2)O(sub 3)-forming alloys. The oxide growth rate decreases by nearly a factor of ten, and the adhesion of oxide scales to alloys is greatly improved. To better understand the mechanisms by which these elements affect oxidation, it is important to know whether or not they are present in the metal ahead of the oxide layer. In this study, the diffusivity of implanted yttrium in a Ni-25 wt %Cr alloy and its distribution in the oxide scale after different oxidation times have been evaluated using secondary ion mass spectroscopy. It was found that only 17 ppm of yttrium was left in the alloy after just 20 minutes of oxidation at 1000(degrees)C. The implanted Y remained concentrated at the oxide/gas interface as the oxide thickened with time. Within the oxide layer, the Y concentration progressively dropped to zero at the scale/alloy interface. These results are discussed in relation to several important mechanisms proposed for the beneficial effects of reactive element additions on scale adhesion. 17 refs., 5 figs.","Distribution of ion-implanted yttrium in Cr2O3 scale and in the underlying Ni-25 wt % Cr alloy Abs: International conference on surface modification of metals by ion beams (SMMIB-7) (7th), Washington, DC (United States), 15-19 Jul 1991. Sponsored by Department of Energy, Washington, DC. tation of yttrium and other reactive metals has been known to show significant effects on the oxidation behavior of Cr(sub 2)O(sub 3)-forming alloys. The oxide growth rate decreases by nearly a factor of ten, and the adhesion of oxide scales to alloys is greatly improved. To better understand the mechanisms by which these elements affect oxidation, it is important to know whether or not they are present in the metal ahead of the oxide layer. In this study, the diffusivity of implanted yttrium in a Ni-25 wt %Cr alloy and its distribution in the oxide scale after different oxidation times have been evaluated using secondary ion mass spectroscopy. It was found that only 17 ppm of yttrium was left in the alloy after just 20 minutes of oxidation at 1000(degrees)C. The implanted Y remained concentrated at the oxide/gas interface as the oxide thickened with time. Within the oxide layer, the Y concentration progressively dropped to zero at the scale/alloy interface. These results are discussed in relation to several important mechanisms proposed for the beneficial effects of reactive element additions on scale adhesion. 17 refs., 5 figs."
1510048,Anderson et al. 1990,"Mechanical property changes and microstructures of dispersion-strengthened copper alloys after neutron irradiation at 411, 414, and 529 C","International symposium on effects of radiation on materials (15th), Nashville, TN (USA), 17-22 Jun 1990. Sponsored by Department of Energy, Washington, DC. sion strengthened copper alloys have shown promise for certain high heat flux applications in both near term and long term fusion devices. This study examines mechanical properties changes and microstructural evolution in several oxide dispersion strengthened alloys which were subjected to high levels of irradiation-induced displacement damage. Irradiations were carried out in FFTF to 34 and 50 dpa at 411--414(degree)C and 32 dpa at 529(degree)C. The alloys include several oxide dispersion-strengthened alloys based on the Cu-Al system, as well as ones based on the Cu-Cr and Cu-Hf systems. Of this group, certain of the Cu-Al alloys, those produced by an internal oxidation technique to contain alumina weight fractions of 0.15 to 0.25% outperformed the other alloys in all respects. These alloys, designated CuAl15, CuAl20, and CuAl25, were found to be resistant to void swelling up to 50 dpa at 414(degree)C, and to retain their superior mechanical and physical properties after extended irradiation. The major factor which controls the stability during irradiation was found to be the dispersoid volume fraction and distribution. The other alloys examined were less resistant to radiation-induced properties changes for a variety of reasons. Some of these include dispersoid redistribution by ballistic resolution, effects of retained dissolved oxygen, and non-uniformity of dispersion distribution. The effect of laser welding was also examined. This joining technique was found to be unacceptable since it destroys the dispersoid distribution and thereby the resistance of the alloys to radiation-induced damage.","Mechanical property changes and microstructures of dispersion-strengthened copper alloys after neutron irradiation at 411, 414, and 529 C Abs: International symposium on effects of radiation on materials (15th), Nashville, TN (USA), 17-22 Jun 1990. Sponsored by Department of Energy, Washington, DC. sion strengthened copper alloys have shown promise for certain high heat flux applications in both near term and long term fusion devices. This study examines mechanical properties changes and microstructural evolution in several oxide dispersion strengthened alloys which were subjected to high levels of irradiation-induced displacement damage. Irradiations were carried out in FFTF to 34 and 50 dpa at 411--414(degree)C and 32 dpa at 529(degree)C. The alloys include several oxide dispersion-strengthened alloys based on the Cu-Al system, as well as ones based on the Cu-Cr and Cu-Hf systems. Of this group, certain of the Cu-Al alloys, those produced by an internal oxidation technique to contain alumina weight fractions of 0.15 to 0.25% outperformed the other alloys in all respects. These alloys, designated CuAl15, CuAl20, and CuAl25, were found to be resistant to void swelling up to 50 dpa at 414(degree)C, and to retain their superior mechanical and physical properties after extended irradiation. The major factor which controls the stability during irradiation was found to be the dispersoid volume fraction and distribution. The other alloys examined were less resistant to radiation-induced properties changes for a variety of reasons. Some of these include dispersoid redistribution by ballistic resolution, effects of retained dissolved oxygen, and non-uniformity of dispersion distribution. The effect of laser welding was also examined. This joining technique was found to be unacceptable since it destroys the dispersoid distribution and thereby the resistance of the alloys to radiation-induced damage."
1510047,Buckmaster 1999,"Fiscal Year 1998 Annual Summary Report for the 200-UP-1,200-ZP-1, and 100-NR-2 Pump-and-Treat Operations and Operable Units","The ERC is currently operating six groundwater pump-and-treat systems across the Hanford Site. Four systems are remediating groundwater in the 100 Area: strontium-90 in the 100-NR-2 OU, and hexavalent chromium in both the 100-KR-4 and 100-HR-3 OUs (there are two sites at this OU). The other two pump-and-treat systems address groundwater contamination in the 200 Area: technetium-99, uranium, carbon tetrachloride (CCl4), and nitrate in the 200-UP-1 OU; and carbon tetrachloride, trichloroethene (TCE), and chloroform (TCM) in the 200-ZP-1 OU. This annual progress report discusses the interim remedial actions in the 200-UP-1 and 200-ZP-1 OUs, and the expedited response action (ERA) in the 100-NR-2 OU. A performance evaluation report for the remediation activities in the 100-KR-4 and 100-HR-3 OUs is prepared under separate cover.","Fiscal Year 1998 Annual Summary Report for the 200-UP-1,200-ZP-1, and 100-NR-2 Pump-and-Treat Operations and Operable Units Abs: The ERC is currently operating six groundwater pump-and-treat systems across the Hanford Site. Four systems are remediating groundwater in the 100 Area: strontium-90 in the 100-NR-2 OU, and hexavalent chromium in both the 100-KR-4 and 100-HR-3 OUs (there are two sites at this OU). The other two pump-and-treat systems address groundwater contamination in the 200 Area: technetium-99, uranium, carbon tetrachloride (CCl4), and nitrate in the 200-UP-1 OU; and carbon tetrachloride, trichloroethene (TCE), and chloroform (TCM) in the 200-ZP-1 OU. This annual progress report discusses the interim remedial actions in the 200-UP-1 and 200-ZP-1 OUs, and the expedited response action (ERA) in the 100-NR-2 OU. A performance evaluation report for the remediation activities in the 100-KR-4 and 100-HR-3 OUs is prepared under separate cover."
1510046,Melendres and  Mini 1998,In-situ spectro-electrochemical studies of radionuclide contaminated surface films on metals and the mechanism of their formation and dissolution. 1998 annual progress report,"The objective of this research program is to gain a fundamental understanding of the structure, composition, and mechanism of formation of radionuclide-containing surface films on metals that are relevant to the problem of decontamination of piping systems and waste storage tanks at DOE nuclear processing facilities. As of May 1998, after about a year and a half of work towards implementing this project, considerable progress has been made in understanding the mechanism and structure of heavy metal ions incorporated into simulated corrosion films of nickel. The nature of iron and chromium oxide films, which are used to model the other components of steels used in piping systems and waste storage tanks in nuclear facilities, has also been elucidated. The principal techniques used in these investigations consist of coupled electrochemical and in-situ synchrotron X-ray absorption spectroscopy, as well as vibrational spectroscopy (infrared and laser Raman).'","In-situ spectro-electrochemical studies of radionuclide contaminated surface films on metals and the mechanism of their formation and dissolution. 1998 annual progress report Abs: The objective of this research program is to gain a fundamental understanding of the structure, composition, and mechanism of formation of radionuclide-containing surface films on metals that are relevant to the problem of decontamination of piping systems and waste storage tanks at DOE nuclear processing facilities. As of May 1998, after about a year and a half of work towards implementing this project, considerable progress has been made in understanding the mechanism and structure of heavy metal ions incorporated into simulated corrosion films of nickel. The nature of iron and chromium oxide films, which are used to model the other components of steels used in piping systems and waste storage tanks in nuclear facilities, has also been elucidated. The principal techniques used in these investigations consist of coupled electrochemical and in-situ synchrotron X-ray absorption spectroscopy, as well as vibrational spectroscopy (infrared and laser Raman).'"
1510045,Balasubramanian et al. 1997,In-situ spectroelectrochemical studies of radionuclide contaminated surface films on metals and the mechanism of their formation and dissolution. 1997 annual progress report,"The incorporation of radioactive contaminants into corrosion product scales on metals is being investigated using in-situ spectroscopic and electrochemical techniques. To facilitate the study, stable isotopes are used initially, while the corrosion films are simulated by electrodeposition of the appropriate oxide (hydroxide) onto a graphite substrate. Synchrotron x-ray absorption spectroscopy (XAS) is used to determine the structure and composition of the host oxide film, as well as the local structure of the impurity ion. Results on the incorporation of Sr and Ce into surface films of Ni(OH)(sub 2) and NiOOH are reported. Cathodically deposited Ni(OH)(sub 2) was found to be mainly in the (alpha) form while anodically prepared NiOOH consists of Ni(sup +2) and Ni(sup +4) phases. Sr in the films consists mainly of Sr(sup 2+) which appears to be coordinated to oxygen atoms and is likely to exist as small domains of co-precipitated material. Ce in Ni(OH)(sub 2) exists mainly as Ce(sup +3) and as a Ce(sup +4) species when co-deposited with NiOOH. The structure of the Ce(sup +4) phase appears similar to a Ce(OH)(sub 4) standard. However, x-ray diffraction and laser Raman measurements indicate that the latter chemical formulation is probably incorrect and that the material is more likely to be a disordered hydrous cerium oxide. Ce chemisorbed on Ni(OH)(sub 2) and NiOOH films is predominantly in the +3 valency state. Iron oxide films prepared by anodic deposition from borate buffer solution containing Fe(sup +2), has been found by XAS to consist mainly of (alpha) FeOOH. The latter has been found by others to be the constituent of the corrosion film on iron; this lends credence to the present simulation approach. Future work will involve studies on the incorporation of radioactive Sr, Ce, and Cs, as well as U, into nickel and iron oxide films. Investigations on the structure and composition of chromium oxide films, the effect of temperature on the energetics and mechanism of incorporation of heavy metal ions, as well as the subsequent dissolution of the films by electroreduction and anodic oxidation, will be undertaken.","In-situ spectroelectrochemical studies of radionuclide contaminated surface films on metals and the mechanism of their formation and dissolution. 1997 annual progress report Abs: The incorporation of radioactive contaminants into corrosion product scales on metals is being investigated using in-situ spectroscopic and electrochemical techniques. To facilitate the study, stable isotopes are used initially, while the corrosion films are simulated by electrodeposition of the appropriate oxide (hydroxide) onto a graphite substrate. Synchrotron x-ray absorption spectroscopy (XAS) is used to determine the structure and composition of the host oxide film, as well as the local structure of the impurity ion. Results on the incorporation of Sr and Ce into surface films of Ni(OH)(sub 2) and NiOOH are reported. Cathodically deposited Ni(OH)(sub 2) was found to be mainly in the (alpha) form while anodically prepared NiOOH consists of Ni(sup +2) and Ni(sup +4) phases. Sr in the films consists mainly of Sr(sup 2+) which appears to be coordinated to oxygen atoms and is likely to exist as small domains of co-precipitated material. Ce in Ni(OH)(sub 2) exists mainly as Ce(sup +3) and as a Ce(sup +4) species when co-deposited with NiOOH. The structure of the Ce(sup +4) phase appears similar to a Ce(OH)(sub 4) standard. However, x-ray diffraction and laser Raman measurements indicate that the latter chemical formulation is probably incorrect and that the material is more likely to be a disordered hydrous cerium oxide. Ce chemisorbed on Ni(OH)(sub 2) and NiOOH films is predominantly in the +3 valency state. Iron oxide films prepared by anodic deposition from borate buffer solution containing Fe(sup +2), has been found by XAS to consist mainly of (alpha) FeOOH. The latter has been found by others to be the constituent of the corrosion film on iron; this lends credence to the present simulation approach. Future work will involve studies on the incorporation of radioactive Sr, Ce, and Cs, as well as U, into nickel and iron oxide films. Investigations on the structure and composition of chromium oxide films, the effect of temperature on the energetics and mechanism of incorporation of heavy metal ions, as well as the subsequent dissolution of the films by electroreduction and anodic oxidation, will be undertaken."
1510044,Deitz ,Regeneration of Whetlerite for Adsorbing Toxic Pollutants from Air,"Patent Application. nvention relates to a method of regenerating adsorbents for removing toxic pollutants from air. More specifically, it relates to a method of restoring the ability of metal oxide-impregnated activated carbon referred to as whetlerite to remove cyanogen chloride from air. Whetlerites are activated carbon-based composites impregnated with ammoniacal solutions of divalent copper and monovalent silver, with or without hexavalent chromium, in various concentrations. Optionally, triethylenediamine (TEDA) is added to prolong the service life of the absorbent and resist the adverse effects of humid environments. Whetlerites adsorb a wide variety of toxic air pollutants, in particular cyanogen chloride, cyanogen, and hydrogen cyanide.","Regeneration of Whetlerite for Adsorbing Toxic Pollutants from Air Abs: Patent Application. nvention relates to a method of regenerating adsorbents for removing toxic pollutants from air. More specifically, it relates to a method of restoring the ability of metal oxide-impregnated activated carbon referred to as whetlerite to remove cyanogen chloride from air. Whetlerites are activated carbon-based composites impregnated with ammoniacal solutions of divalent copper and monovalent silver, with or without hexavalent chromium, in various concentrations. Optionally, triethylenediamine (TEDA) is added to prolong the service life of the absorbent and resist the adverse effects of humid environments. Whetlerites adsorb a wide variety of toxic air pollutants, in particular cyanogen chloride, cyanogen, and hydrogen cyanide."
1510043,Yaroschak 2010,Managing Emerging Contaminant Risks: Plans &amp; Progress,"Briefing charts. ted at the NDIA Environment, Energy Security &amp; Sustainability (E2S2) Symposium &amp; Exhibition held 14-17 June 2010 in Denver, CO. Contains briefing charts only. lent chromium compounds are wonderful corrosion inhibitors. Hexavalent chromium compounds are toxic. We ve learned how to use them safely. It can be expensive to control, store, dispose. Liability issues always loom. National &amp; international procedures and regulations are tightening. There are safer substitutes for some/many applications.","Managing Emerging Contaminant Risks: Plans &amp; Progress Abs: Briefing charts. ted at the NDIA Environment, Energy Security &amp; Sustainability (E2S2) Symposium &amp; Exhibition held 14-17 June 2010 in Denver, CO. Contains briefing charts only. lent chromium compounds are wonderful corrosion inhibitors. Hexavalent chromium compounds are toxic. We ve learned how to use them safely. It can be expensive to control, store, dispose. Liability issues always loom. National &amp; international procedures and regulations are tightening. There are safer substitutes for some/many applications."
1510042,Berman 2011,Air Force Successes and Challenges in Cr(VI) Elimination,"Briefing charts. ted at the National Defense Industrial Association (NDIA) Environment, Energy Security &amp; Sustainability (E2S2) Symposium &amp; Exhibition held 9-12 May 2011 in New Orleans, LA. lent Chromium (Cr(VI)) is an excellent corrosion inhibitor and is highly toxic. National and International regulations and procedures are tightening on Cr(VI) use. DoD is promoting the use of Cr(VI) substitutes. AFRL has a multi-faceted program to eliminate the use of Cr(VI). AFRL Successes Include: Dichromate Sealers -- ready to submit recommendations for TO modifications and transition selected alternative sealer to OC-ALC; An Mg-rich Primer Coating System that is ready for Implementation; and NonLine of Sight (NLOS) Alternatives -- Demonstration of Successful Candidates. AFRL Current Challenges: Conversion Coatings -- There is no magic solution, AF direction is to eliminate Cr completely, no Cr(III); AFRL programs with OO- and OC-ALCs just initiated. AFRL is well poised to meet the future requirements to eliminate Cr(VI).","Air Force Successes and Challenges in Cr(VI) Elimination Abs: Briefing charts. ted at the National Defense Industrial Association (NDIA) Environment, Energy Security &amp; Sustainability (E2S2) Symposium &amp; Exhibition held 9-12 May 2011 in New Orleans, LA. lent Chromium (Cr(VI)) is an excellent corrosion inhibitor and is highly toxic. National and International regulations and procedures are tightening on Cr(VI) use. DoD is promoting the use of Cr(VI) substitutes. AFRL has a multi-faceted program to eliminate the use of Cr(VI). AFRL Successes Include: Dichromate Sealers -- ready to submit recommendations for TO modifications and transition selected alternative sealer to OC-ALC; An Mg-rich Primer Coating System that is ready for Implementation; and NonLine of Sight (NLOS) Alternatives -- Demonstration of Successful Candidates. AFRL Current Challenges: Conversion Coatings -- There is no magic solution, AF direction is to eliminate Cr completely, no Cr(III); AFRL programs with OO- and OC-ALCs just initiated. AFRL is well poised to meet the future requirements to eliminate Cr(VI)."
1510041,Sheetz 2010,USMC Environmental and Corrosion Control Issues,"Briefing charts. ed in collaboration with Marine Corps Systems Command and Elzly Technology. Presented at the Annual Partners in Environmental Technology Technical Symposium &amp; Workshop (15th), Washington, DC, 30 Nov - 2 Dec 2010. Sponsored by SERDP and ESTCP. U.S. Government or Federal Rights License. ited States Marine Corps (USMC) Corrosion Prevention and Control (CPAC) Program is responsible for corrosion control issues for all ground vehicles and support equipment. In this role, the CPAC Program addresses issues through three main areas: Applied Research Development, Testing and Engineering (RDT&amp;E); Corrosion Control Guidance and Support During Acquisition; and Organizational Level Corrosion Maintenance on Fielded Systems. In each of these areas the CPAC Program is striving to reduce the cost and impact of corrosion while supporting the use of environmentally friendly and compliant materials. Currently the areas of greatest need for the USMC are for: Hydraulic Cylinder Coatings, Fasteners, Pretreatments and Primers. Each of these areas has presented a challenge to finding environmentally friendly alternatives to legacy materials or implementing those materials into vehicle production or repair processes. This presentation will discuss some of the challenges the USMC is facing in these areas, some of the internal progress towards implementing new technologies, how the CPAC Program is leveraging the successes of other services in these areas and our overall needs with respect to these issues.","USMC Environmental and Corrosion Control Issues Abs: Briefing charts. ed in collaboration with Marine Corps Systems Command and Elzly Technology. Presented at the Annual Partners in Environmental Technology Technical Symposium &amp; Workshop (15th), Washington, DC, 30 Nov - 2 Dec 2010. Sponsored by SERDP and ESTCP. U.S. Government or Federal Rights License. ited States Marine Corps (USMC) Corrosion Prevention and Control (CPAC) Program is responsible for corrosion control issues for all ground vehicles and support equipment. In this role, the CPAC Program addresses issues through three main areas: Applied Research Development, Testing and Engineering (RDT&amp;E); Corrosion Control Guidance and Support During Acquisition; and Organizational Level Corrosion Maintenance on Fielded Systems. In each of these areas the CPAC Program is striving to reduce the cost and impact of corrosion while supporting the use of environmentally friendly and compliant materials. Currently the areas of greatest need for the USMC are for: Hydraulic Cylinder Coatings, Fasteners, Pretreatments and Primers. Each of these areas has presented a challenge to finding environmentally friendly alternatives to legacy materials or implementing those materials into vehicle production or repair processes. This presentation will discuss some of the challenges the USMC is facing in these areas, some of the internal progress towards implementing new technologies, how the CPAC Program is leveraging the successes of other services in these areas and our overall needs with respect to these issues."
1510040,Perazzola 2010,AF Cr(VI) Minimize Roadmap: Phase 1 Results,"Briefing charts. ted at the Annual Partners in Environmental Technology Technical Symposium &amp; Workshop (15th), Washington, DC, 30 Nov - 2 Dec 2010. Sponsored by SERDP and ESTCP. lent chromium is widely regarded as the highest performing corrosion control treatment for aluminum components. However, due to serious environmental and health risks related to its use, regulations regarding hexavalent chrome exposure are becoming increasingly restrictive. In response, DoD acquisition chief, John J. Young, Jr., published a memo in April 2009 directing all Services to use hexavalent chrome substitutes whenever possible. Yet in many weapon systems, its use has continued due to the lack of chrome- free substitutes able to meet MIL-SPEC requirements and laboratory testing. Hexavalent chrome continues to be used in primers, coatings, and sealants across the Services and aerospace industry. This presentation will discuss efforts the Air Force has already made and its current course in finding suitable replacements for hexavalent chrome.","AF Cr(VI) Minimize Roadmap: Phase 1 Results Abs: Briefing charts. ted at the Annual Partners in Environmental Technology Technical Symposium &amp; Workshop (15th), Washington, DC, 30 Nov - 2 Dec 2010. Sponsored by SERDP and ESTCP. lent chromium is widely regarded as the highest performing corrosion control treatment for aluminum components. However, due to serious environmental and health risks related to its use, regulations regarding hexavalent chrome exposure are becoming increasingly restrictive. In response, DoD acquisition chief, John J. Young, Jr., published a memo in April 2009 directing all Services to use hexavalent chrome substitutes whenever possible. Yet in many weapon systems, its use has continued due to the lack of chrome- free substitutes able to meet MIL-SPEC requirements and laboratory testing. Hexavalent chrome continues to be used in primers, coatings, and sealants across the Services and aerospace industry. This presentation will discuss efforts the Air Force has already made and its current course in finding suitable replacements for hexavalent chrome."
1510039,Goldberg 2010,Hexavalent Chromium Reduction in the Aerospace Industry,"Briefing charts. ted at the Annual Partners in Environmental Technology Technical Symposium and Workshop (15th), held on 30 Nov-2 Dec 2010, in Washington, DC. Sponsored by SERDP and ESTCP. d its members have a long history in minimizing the use of hexavalent chromium in the manufacture of its products. Included in that history are the results of over 25 years of working with DoD engineering professionals through a variety of projects to test hexavalent chromium product replacements. Hexavalent chromium test data have been shared among companies within the industry since the early 1980s. Success in replacement use occurred for some sealant, primer, and plating applications. The industry continues to evaluate replacements for conversion coating, anodizing, descaling, passivation plating, cleaning and many other process and materials applications. Through the many individual company and joint research and testing programs, AIA members learned that the development and implementation of hexavalent chromium replacement compounds is exceptionally complex. Certification and qualification testing continues for many applications due to unique customer or weapon system requirements. Implementation of replacements are often hindered by cost and technical risks to a product's other system requirements. With increasing regulatory and public pressure to further reduce hexavalent chromium usage, the aerospace industry continues to seek alternatives.","Hexavalent Chromium Reduction in the Aerospace Industry Abs: Briefing charts. ted at the Annual Partners in Environmental Technology Technical Symposium and Workshop (15th), held on 30 Nov-2 Dec 2010, in Washington, DC. Sponsored by SERDP and ESTCP. d its members have a long history in minimizing the use of hexavalent chromium in the manufacture of its products. Included in that history are the results of over 25 years of working with DoD engineering professionals through a variety of projects to test hexavalent chromium product replacements. Hexavalent chromium test data have been shared among companies within the industry since the early 1980s. Success in replacement use occurred for some sealant, primer, and plating applications. The industry continues to evaluate replacements for conversion coating, anodizing, descaling, passivation plating, cleaning and many other process and materials applications. Through the many individual company and joint research and testing programs, AIA members learned that the development and implementation of hexavalent chromium replacement compounds is exceptionally complex. Certification and qualification testing continues for many applications due to unique customer or weapon system requirements. Implementation of replacements are often hindered by cost and technical risks to a product's other system requirements. With increasing regulatory and public pressure to further reduce hexavalent chromium usage, the aerospace industry continues to seek alternatives."
1510038,Scott 2011,Environmentally Friendly Anticorrosion Coating for High Strength Fasteners,"Final rept. 1 Oct 2008-30 Sep 2010. Project WP-1617, The original document contains color images. exists a need for environmentally benign coatings to eliminate cadmium and/or chromate containing coatings on high-strength fasteners. These alternative replacement coatings would provide high-strength, corrosion resistant fasteners for use in weapon systems. Traditionally, high-strength steels have been used with cadmium (Cd) electroplated coatings, followed by a hexavalent chromium (Cr6+) rinse. The environmental and human health hazards associated with both cadmium and chromates are well established. The elimination of hazardous materials will improve the life cycle costs and environmental / occupational health issues associated with the manufacture and maintenance of DoD weapon systems. Alternatives to both processes have been pursued with very promising results. This work describes a multi-layer approach to provide a protective coating system. These systems include a sacrificial metal base coat and may also include an organic topcoat technology that will provide the best combination of corrosion resistance and barrier properties. These approaches impart high end sacrificial corrosion resistance properties without use of hazardous Cr or Cd and without hydrogen embrittlement of fasteners.","Environmentally Friendly Anticorrosion Coating for High Strength Fasteners Abs: Final rept. 1 Oct 2008-30 Sep 2010. Project WP-1617, The original document contains color images. exists a need for environmentally benign coatings to eliminate cadmium and/or chromate containing coatings on high-strength fasteners. These alternative replacement coatings would provide high-strength, corrosion resistant fasteners for use in weapon systems. Traditionally, high-strength steels have been used with cadmium (Cd) electroplated coatings, followed by a hexavalent chromium (Cr6+) rinse. The environmental and human health hazards associated with both cadmium and chromates are well established. The elimination of hazardous materials will improve the life cycle costs and environmental / occupational health issues associated with the manufacture and maintenance of DoD weapon systems. Alternatives to both processes have been pursued with very promising results. This work describes a multi-layer approach to provide a protective coating system. These systems include a sacrificial metal base coat and may also include an organic topcoat technology that will provide the best combination of corrosion resistance and barrier properties. These approaches impart high end sacrificial corrosion resistance properties without use of hazardous Cr or Cd and without hydrogen embrittlement of fasteners."
1510037,Leblanc and  Cunniff 2011,Making Sense of the Changing Global Supply Landscape: New Rules and Reformulations,"Journal article. hed in Defense AT&amp;L, p16-20 Jul-Aug 2011. obal nature of military supply chains means that evolving chemical regulations throughout the world are triggering product reformulations and affecting the work of acquisition professionals. When defense contractors purchase from, and build for, a global market, the most stringent chemical regulations in the supply network drive the availability, use, and disposal of constituent materials in weapon systems and equipment. How can acquisition professionals successfully adapt to this changing global landscape. The Law of Unintended Consequences Currently, the most stringent chemical regulation is the European Union's (EU's) REACH (Registration, Evaluation, Authorisation, and Restriction of Chemicals) regulation. Although in its early stages of implementation, it is already driving product reformulations across the globe as industries move away from using known hazardous materials to inherently more benign ones. REACH, and other evolving international chemical regulations will increasingly affect the cost, performance, and schedule of weapons acquisition programs due to product reformulations. For example, in July 2006, the EU promulgated a new regulation entitled 'Restriction of Hazardous Substances' (RoHS), which limits the use of lead, mercury, cadmium, hexavalent chromium, and other chemicals in products. The restriction on lead prompted manufacturers to switch to lead-free solder alloys and pure tin termination finishes in a broad array of electronic equipment. Pure tin finishes develop 'whiskers' that can short-circuit crucial electronics in aircraft and other critical military applications; and the reliability of lead-free solder alloys has not been proven in military and aerospace applications.","Making Sense of the Changing Global Supply Landscape: New Rules and Reformulations Abs: Journal article. hed in Defense AT&amp;L, p16-20 Jul-Aug 2011. obal nature of military supply chains means that evolving chemical regulations throughout the world are triggering product reformulations and affecting the work of acquisition professionals. When defense contractors purchase from, and build for, a global market, the most stringent chemical regulations in the supply network drive the availability, use, and disposal of constituent materials in weapon systems and equipment. How can acquisition professionals successfully adapt to this changing global landscape. The Law of Unintended Consequences Currently, the most stringent chemical regulation is the European Union's (EU's) REACH (Registration, Evaluation, Authorisation, and Restriction of Chemicals) regulation. Although in its early stages of implementation, it is already driving product reformulations across the globe as industries move away from using known hazardous materials to inherently more benign ones. REACH, and other evolving international chemical regulations will increasingly affect the cost, performance, and schedule of weapons acquisition programs due to product reformulations. For example, in July 2006, the EU promulgated a new regulation entitled 'Restriction of Hazardous Substances' (RoHS), which limits the use of lead, mercury, cadmium, hexavalent chromium, and other chemicals in products. The restriction on lead prompted manufacturers to switch to lead-free solder alloys and pure tin termination finishes in a broad array of electronic equipment. Pure tin finishes develop 'whiskers' that can short-circuit crucial electronics in aircraft and other critical military applications; and the reliability of lead-free solder alloys has not been proven in military and aerospace applications."
1510036,Paulson et al. 2009,Field Testing Pulsed Power Inverters in Welding Operations to Control Heavy Metal Emissions,"Final rept. 2002-2006. iginal document contains color images. tudy evaluated the emission reduction of hexavalent chromium , nickel, manganese and other metals generated during welding operations while using pulsed power inverter (PPI) technology. Particle size distribution and metal sp4ecies differentiation within each particle size was examined using gravimetric and laboratory analyses. Emissions from ozone, carbon monoxide and nitrogen oxides were evaluated using real-time monitoring. Emissions for operations using PPI technology were compared with welding processes, typically mild steel, used during maintenance operations at four DOD facilities. The goal was to confirm manufacturer's claims of significant metals reduction while using PPI Technology. There may be an increase in productivity and, once acclimated, welders accepted the new technology. However, the study did not find a significant reduction in weld fume constituent (metals) emissions on the four DOD operations studied. Welding material quality using PPI was similar to the currently used or conventional gas metal and metal arc (GMAW) and flux core arc welding (FCAW) operations.","Field Testing Pulsed Power Inverters in Welding Operations to Control Heavy Metal Emissions Abs: Final rept. 2002-2006. iginal document contains color images. tudy evaluated the emission reduction of hexavalent chromium , nickel, manganese and other metals generated during welding operations while using pulsed power inverter (PPI) technology. Particle size distribution and metal sp4ecies differentiation within each particle size was examined using gravimetric and laboratory analyses. Emissions from ozone, carbon monoxide and nitrogen oxides were evaluated using real-time monitoring. Emissions for operations using PPI technology were compared with welding processes, typically mild steel, used during maintenance operations at four DOD facilities. The goal was to confirm manufacturer's claims of significant metals reduction while using PPI Technology. There may be an increase in productivity and, once acclimated, welders accepted the new technology. However, the study did not find a significant reduction in weld fume constituent (metals) emissions on the four DOD operations studied. Welding material quality using PPI was similar to the currently used or conventional gas metal and metal arc (GMAW) and flux core arc welding (FCAW) operations."
1510035,Deshusses and  Matsumoto 2010,Field Demonstration of a Novel Biotreatment Process for Perchlorate Reduction in Groundwater,"Final rept. Project ER-200636, The original document contains color images. Prepared in cooperation with the University of California. nology demonstration was conducted at the Well No. 2 in Rialto, California to treat perchlorate contaminated groundwater using a novel biological treatment system. The new treatment relies on autotrophic perchlorate reducing bacteria immobilized on zero valent iron (ZVI). As ZVI corrodes in water, hydrogen is released from the reduction of water which is then used by perchlorate reducing bacteria as a source of electrons. Prior to this technology demonstration, we conducted extensive research in the laboratory to determine the treatment performance under a range of simulated field conditions and to develop a better understanding of the treatment process. The results of the laboratory studies formed the basis of this ESTCP award, as they showed that the process was very promising with relatively high perchlorate reduction rates. Also, hydrogen has significant advantages compared to organic carbon as an electron donor. It minimizes biomass growth and has a low potential for disinfection by-products precursors compared to organic substrates such as acetate. Other potential advantages include the possible reduction (biotic or abiotic) of nitrate, TCE, hexavalent chromium, and the possible control by adsorption of chromium, uranium, and arsenic ions. The concept could also be translated into subsurface treatment, for example in a funnel and gate reactive barrier. The main objective of this project was to test and demonstrate the efficacy of the ZVI supported biological reduction of perchlorate. Additional objectives were to 1) obtain pertinent data that will guide full-scale design and operation, 2) provide relevant data for treatment cost estimation and comparison, 3) provide the necessary data leading to possible permitting of the process by California DPH, and 4) disseminate the results in various forms to promote technology transfer.","Field Demonstration of a Novel Biotreatment Process for Perchlorate Reduction in Groundwater Abs: Final rept. Project ER-200636, The original document contains color images. Prepared in cooperation with the University of California. nology demonstration was conducted at the Well No. 2 in Rialto, California to treat perchlorate contaminated groundwater using a novel biological treatment system. The new treatment relies on autotrophic perchlorate reducing bacteria immobilized on zero valent iron (ZVI). As ZVI corrodes in water, hydrogen is released from the reduction of water which is then used by perchlorate reducing bacteria as a source of electrons. Prior to this technology demonstration, we conducted extensive research in the laboratory to determine the treatment performance under a range of simulated field conditions and to develop a better understanding of the treatment process. The results of the laboratory studies formed the basis of this ESTCP award, as they showed that the process was very promising with relatively high perchlorate reduction rates. Also, hydrogen has significant advantages compared to organic carbon as an electron donor. It minimizes biomass growth and has a low potential for disinfection by-products precursors compared to organic substrates such as acetate. Other potential advantages include the possible reduction (biotic or abiotic) of nitrate, TCE, hexavalent chromium, and the possible control by adsorption of chromium, uranium, and arsenic ions. The concept could also be translated into subsurface treatment, for example in a funnel and gate reactive barrier. The main objective of this project was to test and demonstrate the efficacy of the ZVI supported biological reduction of perchlorate. Additional objectives were to 1) obtain pertinent data that will guide full-scale design and operation, 2) provide relevant data for treatment cost estimation and comparison, 3) provide the necessary data leading to possible permitting of the process by California DPH, and 4) disseminate the results in various forms to promote technology transfer."
1510034,Johnson 2007,Magnesium Rich Primer for Chrome Free Protection of Aluminum Alloys (Preprint),"Final rept. lent chromium compounds used for corrosion protection are one of the top hazardous waste materials generated by the U.S. Air Force and legislation is in effect to further restrict their use. Magnesium rich primers that utilize sacrificial magnesium metal pigment to cathodically protect aerospace aluminum alloy substrates are a potential alternative to chromated primers. This material has proven to be particularly effective as part of a completely chromate-free coating system in which a non film forming surface treatment and an Advanced Performance Coating (APC) grade topcoat are utilized. Samples using the latest advanced formulations show excellent corrosion protection of scribed AA2024-T3 panels in both ASTM B 177 and outdoor exposure at Dayton Beach, FL. Despite initial concerns regarding the reactivity of the magnesium metal pigment being used, the flammability and handling characteristics have not shown any potential problems to date. Transitioning a new class of corrosion protective primer coating such as this requires more testing than normal. The current Air Force plan involves qualification to a 'system level' coating specification, MIL-PRF-32239. In addition, simulated lap joints with various fasteners specific to the target aircraft will be evaluated, along with compatibility on alternative substrates and evaluation of coating reparability characteristics.","Magnesium Rich Primer for Chrome Free Protection of Aluminum Alloys (Preprint) Abs: Final rept. lent chromium compounds used for corrosion protection are one of the top hazardous waste materials generated by the U.S. Air Force and legislation is in effect to further restrict their use. Magnesium rich primers that utilize sacrificial magnesium metal pigment to cathodically protect aerospace aluminum alloy substrates are a potential alternative to chromated primers. This material has proven to be particularly effective as part of a completely chromate-free coating system in which a non film forming surface treatment and an Advanced Performance Coating (APC) grade topcoat are utilized. Samples using the latest advanced formulations show excellent corrosion protection of scribed AA2024-T3 panels in both ASTM B 177 and outdoor exposure at Dayton Beach, FL. Despite initial concerns regarding the reactivity of the magnesium metal pigment being used, the flammability and handling characteristics have not shown any potential problems to date. Transitioning a new class of corrosion protective primer coating such as this requires more testing than normal. The current Air Force plan involves qualification to a 'system level' coating specification, MIL-PRF-32239. In addition, simulated lap joints with various fasteners specific to the target aircraft will be evaluated, along with compatibility on alternative substrates and evaluation of coating reparability characteristics."
1510033,Lange 2006,Dissociation of Hexavalent Chromium from Sanded Paint Particles into a Simulated Lung Fluid,"Master's thesis. te-containing paint coatings are the primary means of protecting an aircraft surface from corrosion in the US military. Studies clearly link chromate exposure to human lung cancer. However, the few studies of the painting industry suggest that chromate exposure from paint particles does not increase the risk of lung cancer. Even fewer studies have evaluated sanding of chromate containing paint layers, and data suggests that sanders have an increased risk of lung cancer. A 6-stage cascade impactor was used to imitate particle deposition onto a layer of lung fluid. The lung fluid was simulated with a porcine based mucin. Sanded particles were collected based on particle size into the impactor's six petri dishes, which contained lung fluid. After 24 hours, the fraction of chromate that dissolved into the lung fluid generally ranged from 60-90% for strontium chromate based paints and 10-50% for barium chromate based paints. In water and solvent based strontium chromate paints, there was lifetime difference between sanded and freshly sprayed paint particles. But for polyurethane and barium chromate based paints, sanded particles dissociated significantly more chromate than paint particles.","Dissociation of Hexavalent Chromium from Sanded Paint Particles into a Simulated Lung Fluid Abs: Master's thesis. te-containing paint coatings are the primary means of protecting an aircraft surface from corrosion in the US military. Studies clearly link chromate exposure to human lung cancer. However, the few studies of the painting industry suggest that chromate exposure from paint particles does not increase the risk of lung cancer. Even fewer studies have evaluated sanding of chromate containing paint layers, and data suggests that sanders have an increased risk of lung cancer. A 6-stage cascade impactor was used to imitate particle deposition onto a layer of lung fluid. The lung fluid was simulated with a porcine based mucin. Sanded particles were collected based on particle size into the impactor's six petri dishes, which contained lung fluid. After 24 hours, the fraction of chromate that dissolved into the lung fluid generally ranged from 60-90% for strontium chromate based paints and 10-50% for barium chromate based paints. In water and solvent based strontium chromate paints, there was lifetime difference between sanded and freshly sprayed paint particles. But for polyurethane and barium chromate based paints, sanded particles dissociated significantly more chromate than paint particles."
1510031,Sartwell et al. 2005,Replacement of Chromium Electroplating on Gas Turbine Engine Components Using Thermal Spray Coatings,"Memorandum rept. for May 2000-May 2005. iginal document contains color images. Project no. EPP-0023. Performed in cooperation with Rowan Technology Group, Libertyville, IL, GE Aircraft Engines, Cincinnati, OH, Pratt AND Whitney, East Hartford, CT, Metcut Research Inc., Cincinnati, OH, and Concurrent Technologies Corp., Johnstown, PA. hromium electroplating is extensively used by aircraft manufacturers and military maintenance depots to provide wear and/or corrosion resistance or to restore dimensional tolerance to components. However, chrome plating utilizes hexavalent chromium, which is a highly toxic carcinogen, and increasingly, stringent environmental and worker-safety regulations are making chrome plating more expensive for the DoD. This document constitutes the final report on a project to qualify high-velocity oxygen-fuel (HVOF) and plasma thermal spray coatings as a replacement for hard chrome plating on gas turbine engine components. Extensive fatigue, fretting wear, salt-fog corrosion, and carbon-seal wear tests were performed on HVOF, WC/17Co, Tribaloy 400, Tribaloy 800, and Cr3C2/20(NiCr), and plasma-sprayed Tribaloy 400 coatings compared to hard chromium. In general, the HVOF WC/17Co coatings demonstrated superior performance. An accelerated test on a TF33 engine containing seven components coated with HVOF WC/17Co showed superior performance to what would have been expected using the standard hard chromium. A cost/benefit analysis indicates that military repair depots that overhaul gas turbine engines can realize substantial savings by converting from hard chrome to HVOF.","Replacement of Chromium Electroplating on Gas Turbine Engine Components Using Thermal Spray Coatings Abs: Memorandum rept. for May 2000-May 2005. iginal document contains color images. Project no. EPP-0023. Performed in cooperation with Rowan Technology Group, Libertyville, IL, GE Aircraft Engines, Cincinnati, OH, Pratt AND Whitney, East Hartford, CT, Metcut Research Inc., Cincinnati, OH, and Concurrent Technologies Corp., Johnstown, PA. hromium electroplating is extensively used by aircraft manufacturers and military maintenance depots to provide wear and/or corrosion resistance or to restore dimensional tolerance to components. However, chrome plating utilizes hexavalent chromium, which is a highly toxic carcinogen, and increasingly, stringent environmental and worker-safety regulations are making chrome plating more expensive for the DoD. This document constitutes the final report on a project to qualify high-velocity oxygen-fuel (HVOF) and plasma thermal spray coatings as a replacement for hard chrome plating on gas turbine engine components. Extensive fatigue, fretting wear, salt-fog corrosion, and carbon-seal wear tests were performed on HVOF, WC/17Co, Tribaloy 400, Tribaloy 800, and Cr3C2/20(NiCr), and plasma-sprayed Tribaloy 400 coatings compared to hard chromium. In general, the HVOF WC/17Co coatings demonstrated superior performance. An accelerated test on a TF33 engine containing seven components coated with HVOF WC/17Co showed superior performance to what would have been expected using the standard hard chromium. A cost/benefit analysis indicates that military repair depots that overhaul gas turbine engines can realize substantial savings by converting from hard chrome to HVOF."
1510030,Moran and  Lapuma 2005,Dissociation of Hexavalent Chromium from Primer Paint Particles into Simulated Mucus Fluid,"Master's thesis. litary relies heavily on chromate primer paints to protect equipment from corrosion. Epidemiological studies link chromate exposure to cancer however limited studies suggest exposure to chromate paint particles does not increase the risk of lung cancer. The particle size and paint type may hinder chromate released into lung fluid. To simulate particle deposition in the mucosal layer of the lungs, a viable cascade impactor collected paint particles into porcine-based simulated lung fluid (SLF). Samples were tested after 24 hours for dissolved and total chromate to determine the fraction of Cr(exp +6)(exp +6) that dissociated from the particles into the Porcine-SLF. In strontium chromate paints, 0.65-2.1 microns sized particles released significantly less chromate than 2.1-7.0 micron sizes. Barium chromate paints only released 3-7% of its chromate, while strontium based paints released from 20-90%. This method demonstrates a technique to evaluate the bioavailability of contaminants from any type of aerosols.","Dissociation of Hexavalent Chromium from Primer Paint Particles into Simulated Mucus Fluid Abs: Master's thesis. litary relies heavily on chromate primer paints to protect equipment from corrosion. Epidemiological studies link chromate exposure to cancer however limited studies suggest exposure to chromate paint particles does not increase the risk of lung cancer. The particle size and paint type may hinder chromate released into lung fluid. To simulate particle deposition in the mucosal layer of the lungs, a viable cascade impactor collected paint particles into porcine-based simulated lung fluid (SLF). Samples were tested after 24 hours for dissolved and total chromate to determine the fraction of Cr(exp +6)(exp +6) that dissociated from the particles into the Porcine-SLF. In strontium chromate paints, 0.65-2.1 microns sized particles released significantly less chromate than 2.1-7.0 micron sizes. Barium chromate paints only released 3-7% of its chromate, while strontium based paints released from 20-90%. This method demonstrates a technique to evaluate the bioavailability of contaminants from any type of aerosols."
1510029,Kelley 2004,"Assessment of Some Chromated and Non-Chromated Primers on Magnesium ZE41A, Aluminum 2024, and Steel 4340 Via Electro-Chemical Impedance Spectroscopy","Final rept. Jan-May 2004. iginal document contains color images. Project no. 622618-H80. c coating systems are one of the most efficient methods for protecting metals from corrosion, and the use of chromate primers vastly improves corrosion protection. However, environmental concerns about hexavalent chromium (Cr+6) toxicity have led to the development of many non-chromate coatings. In recent years, water-borne coatings have emerged as viable alternatives and provide the additional advantage of having low content of volatile organic compounds. Since the performance of chromated coatings tends to exceed that of their environmentally friendly counterparts, evaluations of some non-chromate alternatives need to be performed. This report compares the performance of three military primers: MIL-P-23377C (chromated), MIL-P-85582C (chromated), and MIL-P-85582N (non-chromated) on three common military alloys.","Assessment of Some Chromated and Non-Chromated Primers on Magnesium ZE41A, Aluminum 2024, and Steel 4340 Via Electro-Chemical Impedance Spectroscopy Abs: Final rept. Jan-May 2004. iginal document contains color images. Project no. 622618-H80. c coating systems are one of the most efficient methods for protecting metals from corrosion, and the use of chromate primers vastly improves corrosion protection. However, environmental concerns about hexavalent chromium (Cr+6) toxicity have led to the development of many non-chromate coatings. In recent years, water-borne coatings have emerged as viable alternatives and provide the additional advantage of having low content of volatile organic compounds. Since the performance of chromated coatings tends to exceed that of their environmentally friendly counterparts, evaluations of some non-chromate alternatives need to be performed. This report compares the performance of three military primers: MIL-P-23377C (chromated), MIL-P-85582C (chromated), and MIL-P-85582N (non-chromated) on three common military alloys."
1510028,Smith et al. 2004,Replacement Alternatives to the Chromate Wash Primer DOD-P-15328D,"Interim rept. for 1999-2003. iginal document contains color images. jor advantage of the Department of Defense (DOD)-P-15328DD1 wash primer is to enhance corrosion resistance through the passivation of the metal surface. In the U.S. Army's Chemical Agent Resistant Coating (CARC) system, the wash primer DOD-P-15328D is overcoated with an epoxy primer and followed by a camouflage urethane topcoat. Several coating procedures specify the use of the wash primer, DOD-P-15328D, as a surface treatment prior to the application of an epoxy primer/polyurethane topcoat CARC system. The current wash primer contains large amounts of volatile organic compounds (VOCs) and hazardous air pollutants (HAPs) that impact coating operations due to air pollution regulations that may require the use of control devices to reduce the total VOC/HAP emissions to the atmosphere. The U.S. Army Research Laboratory (ARL) has evaluated new water-reducible wash primers that do not contain hexavalent chromium and significantly minimize VOC and HAP. Coatings have been extensively tested for accelerated corrosion and adhesion and have completed 2 years of outdoor exposure testing. ARL will conduct tests on military equipment to validate the lab and controlled testing previously completed. Affected installations, facilities, and weapons systems are excellent candidates for this evaluation because application of DOD-P-15328D is a key step prior to applying the remaining CARC system coating.","Replacement Alternatives to the Chromate Wash Primer DOD-P-15328D Abs: Interim rept. for 1999-2003. iginal document contains color images. jor advantage of the Department of Defense (DOD)-P-15328DD1 wash primer is to enhance corrosion resistance through the passivation of the metal surface. In the U.S. Army's Chemical Agent Resistant Coating (CARC) system, the wash primer DOD-P-15328D is overcoated with an epoxy primer and followed by a camouflage urethane topcoat. Several coating procedures specify the use of the wash primer, DOD-P-15328D, as a surface treatment prior to the application of an epoxy primer/polyurethane topcoat CARC system. The current wash primer contains large amounts of volatile organic compounds (VOCs) and hazardous air pollutants (HAPs) that impact coating operations due to air pollution regulations that may require the use of control devices to reduce the total VOC/HAP emissions to the atmosphere. The U.S. Army Research Laboratory (ARL) has evaluated new water-reducible wash primers that do not contain hexavalent chromium and significantly minimize VOC and HAP. Coatings have been extensively tested for accelerated corrosion and adhesion and have completed 2 years of outdoor exposure testing. ARL will conduct tests on military equipment to validate the lab and controlled testing previously completed. Affected installations, facilities, and weapons systems are excellent candidates for this evaluation because application of DOD-P-15328D is a key step prior to applying the remaining CARC system coating."
1510027,Sartwell et al. 2004,"Replacement of Chromium Electroplating on C-2, E-2, P-3 and C-130 Propeller Hub Components Using HVOF Thermal Spray Coatings","Final rept. iginal document contains color images. All DTIC reproductions will be in black and white. hromium electroplating is extensively used by aircraft manufacturers and military maintenance depots to provide wear and/or corrosion resistance or to restore dimensional tolerance to components. However, chrome plating utilizes hexavalent chromium, winch is a highly toxic carcinogen, and increasingly stringent environmental and worker-safety regulations are making chrome plating more expensive for the DoD. This document constitutes the final report on a project to qualify high-velocity oxygen-fuel (HVOF) thermal spray coatings as a replacement for hard chrome plating on propeller hub components from various military aircraft. Extensive fatigue, wear, and corrosion test results comparing HVOF WC/l7Co, WC/lOCo4Cr, and Tribaloy 800 coatings against hard chrome are presented. In general, the performance of the HvOF coatings was superior to hard chrome. A rig test on a P-3 low-pitch-stop lever sleeve coated with WC/l7Co showed acceptable performance. A cost/benefit analysis conducted for a military repair depot that overhauls propeller hub components showed a slight cost increase associated with use of the HVOF coatings.","Replacement of Chromium Electroplating on C-2, E-2, P-3 and C-130 Propeller Hub Components Using HVOF Thermal Spray Coatings Abs: Final rept. iginal document contains color images. All DTIC reproductions will be in black and white. hromium electroplating is extensively used by aircraft manufacturers and military maintenance depots to provide wear and/or corrosion resistance or to restore dimensional tolerance to components. However, chrome plating utilizes hexavalent chromium, winch is a highly toxic carcinogen, and increasingly stringent environmental and worker-safety regulations are making chrome plating more expensive for the DoD. This document constitutes the final report on a project to qualify high-velocity oxygen-fuel (HVOF) thermal spray coatings as a replacement for hard chrome plating on propeller hub components from various military aircraft. Extensive fatigue, wear, and corrosion test results comparing HVOF WC/l7Co, WC/lOCo4Cr, and Tribaloy 800 coatings against hard chrome are presented. In general, the performance of the HvOF coatings was superior to hard chrome. A rig test on a P-3 low-pitch-stop lever sleeve coated with WC/l7Co showed acceptable performance. A cost/benefit analysis conducted for a military repair depot that overhauls propeller hub components showed a slight cost increase associated with use of the HVOF coatings."
1510026,Sartwell et al. 2004,Validation of HVOF WC/Co Thermal Spray Coatings as a Replacement for Hard Chrome Plating on Aircraft Landing Gear,"Final rept. iginal document contains color images. All DTIC reproductions will be in black and white. Prepared in collaboration with Rowan Technology Group, Libertyville, IL, GB Aircraft Engines, Cincinnati, OH, Sauer Engineering, Cincinnati, Oh, Boeing Corp., Seattle, WA, Metcut Research Inc., Cincinnati, OH, and General Atomics, Ogden, UT. hromium electroplating is extensively used by aircraft manufacturers and military maintenance depots to provide wear and/or corrosion resistance or to restore dimensional tolerance to components. However, chrome plating utilizes hexavalent chromium, which is a highly toxic carcinogen, and increasingly stringent environmental and worker-safety regulations are making chrome plating more expensive for the DoD. This document constitutes the final report on a project to quality high-velocity oxygen-fuel (HVOF) thermal spray WC/Co coatings as a replacement for hard chrome plating on landing gear components. Extensive fatigue, wear, corrosion, impact, and hydrogen embrittlement test results comparing the WC/Co coatings against hard chrome are presented. The results of rig and flight-testing of HVOF WC/Co coatings on landing gear components are also presented. in general, the performance of the WC/Co coatings was superior to hard chrome. Producibility issues such as stripping, grinding, and non-destructive inspection of the coatings were addressed. Cost/Benefit analyses indicate that military repair depots that overhaul landing gear can realize substantial savings by converting from hard chrome to HVOF. Specifications were developed for the WC/Co powder, the coatings deposition parameters, and the grinding of the WC/Co coatings.","Validation of HVOF WC/Co Thermal Spray Coatings as a Replacement for Hard Chrome Plating on Aircraft Landing Gear Abs: Final rept. iginal document contains color images. All DTIC reproductions will be in black and white. Prepared in collaboration with Rowan Technology Group, Libertyville, IL, GB Aircraft Engines, Cincinnati, OH, Sauer Engineering, Cincinnati, Oh, Boeing Corp., Seattle, WA, Metcut Research Inc., Cincinnati, OH, and General Atomics, Ogden, UT. hromium electroplating is extensively used by aircraft manufacturers and military maintenance depots to provide wear and/or corrosion resistance or to restore dimensional tolerance to components. However, chrome plating utilizes hexavalent chromium, which is a highly toxic carcinogen, and increasingly stringent environmental and worker-safety regulations are making chrome plating more expensive for the DoD. This document constitutes the final report on a project to quality high-velocity oxygen-fuel (HVOF) thermal spray WC/Co coatings as a replacement for hard chrome plating on landing gear components. Extensive fatigue, wear, corrosion, impact, and hydrogen embrittlement test results comparing the WC/Co coatings against hard chrome are presented. The results of rig and flight-testing of HVOF WC/Co coatings on landing gear components are also presented. in general, the performance of the WC/Co coatings was superior to hard chrome. Producibility issues such as stripping, grinding, and non-destructive inspection of the coatings were addressed. Cost/Benefit analyses indicate that military repair depots that overhaul landing gear can realize substantial savings by converting from hard chrome to HVOF. Specifications were developed for the WC/Co powder, the coatings deposition parameters, and the grinding of the WC/Co coatings."
1510025,Sopok 1995,Determination of Wastewater Acids from Chromium Plating and Electropolishing Solutions,"Benet Internal Technical rept. rpose of this report is to provide calibration data for the online UV-visible, conductivity, and pH detectors associated with the environmental thrust project, which is part of the Benet Laboratories vessel plating program. The chemical literature provides offline laboratory detection of chromic acid from chromium plating wastewater solutions, as well as phosphoric and sulfuric acids from electropolishing wastewater solutions. The chemical literature lacks online detection and calibration data for these wastewater acids and this is essential for the reclamation of these three acids. Not only are these chemical resources wasted if they are not reclaimed, but the U.S. Army pays increasingly more to dispose of these hazardous materials. Specific methods are illustrated here that do provide online detection and calibration of these chromium plating and electropolishing wastewater acids. These methods consist of online UV-visible, conductivity, and pH detection. These data and their associated precisions are sufficient to adequately calibrate these three detectors associated with the environmental thrust project.","Determination of Wastewater Acids from Chromium Plating and Electropolishing Solutions Abs: Benet Internal Technical rept. rpose of this report is to provide calibration data for the online UV-visible, conductivity, and pH detectors associated with the environmental thrust project, which is part of the Benet Laboratories vessel plating program. The chemical literature provides offline laboratory detection of chromic acid from chromium plating wastewater solutions, as well as phosphoric and sulfuric acids from electropolishing wastewater solutions. The chemical literature lacks online detection and calibration data for these wastewater acids and this is essential for the reclamation of these three acids. Not only are these chemical resources wasted if they are not reclaimed, but the U.S. Army pays increasingly more to dispose of these hazardous materials. Specific methods are illustrated here that do provide online detection and calibration of these chromium plating and electropolishing wastewater acids. These methods consist of online UV-visible, conductivity, and pH detection. These data and their associated precisions are sufficient to adequately calibrate these three detectors associated with the environmental thrust project."
1510023,Rhodes 2002,Chromate Content Bias Versus Overspray Particle Size in Three Aircraft Primer Paints,"Master's thesis Aug 2000-Mar 2002. iginal document contains color images. ited States Air Force relies on the corrosion inhibiting properties of chromate-containing primer paints to protect the aluminum skin of its aircraft. Hexavalent chromium (Cr6+) the ingredient responsible for the corrosion inhibiting characteristics of these primers is a known human carcinogen. The concentration of Cr6+ in different particle sizes of paint overspray is important to understand health implications to painters as well as filtration efficiency. Previous research indicates disproportionately less Cr6+ content in smaller particles collected in the overspray of solvent-based epoxy- polyamide paint primers (MIL-P-2377G). This research explores the possibility of a particle size bias in the Cr6+ content of three commonly used aircraft primers: solvent-based epoxy-polyamide, water-based epoxy-polyamide (MIL-PRF- 85582C), and solvent-based polyurethane (TT-P-2760A). The mass ratio of air flow to paint flow (A/P ratio) was varied during initial atomization. Seven-stage cascade impactors collected overspray particles into distinct bins with particle size cutoff diameters ranging from 0.7 mm to 34.1 mm. The mass of the dry paint collected in each bin was determined and analyzed for Cr6+ with an Atomic Absorption Spectrometer. In all three primers, smaller particles contained disproportionately less Cr6+ per mass of dry paint than larger particles. Particles with an aerodynamic diameter under 7 mm contained less Cr6+ per mass of dry paint as the particles became smaller. Particles less than 2.6 mm have a mean Cr6+ content of approximately one-third of the expected value. The range of A/P ratios tested in this study had no effect on the Cr6+ content in the overspray.","Chromate Content Bias Versus Overspray Particle Size in Three Aircraft Primer Paints Abs: Master's thesis Aug 2000-Mar 2002. iginal document contains color images. ited States Air Force relies on the corrosion inhibiting properties of chromate-containing primer paints to protect the aluminum skin of its aircraft. Hexavalent chromium (Cr6+) the ingredient responsible for the corrosion inhibiting characteristics of these primers is a known human carcinogen. The concentration of Cr6+ in different particle sizes of paint overspray is important to understand health implications to painters as well as filtration efficiency. Previous research indicates disproportionately less Cr6+ content in smaller particles collected in the overspray of solvent-based epoxy- polyamide paint primers (MIL-P-2377G). This research explores the possibility of a particle size bias in the Cr6+ content of three commonly used aircraft primers: solvent-based epoxy-polyamide, water-based epoxy-polyamide (MIL-PRF- 85582C), and solvent-based polyurethane (TT-P-2760A). The mass ratio of air flow to paint flow (A/P ratio) was varied during initial atomization. Seven-stage cascade impactors collected overspray particles into distinct bins with particle size cutoff diameters ranging from 0.7 mm to 34.1 mm. The mass of the dry paint collected in each bin was determined and analyzed for Cr6+ with an Atomic Absorption Spectrometer. In all three primers, smaller particles contained disproportionately less Cr6+ per mass of dry paint than larger particles. Particles with an aerodynamic diameter under 7 mm contained less Cr6+ per mass of dry paint as the particles became smaller. Particles less than 2.6 mm have a mean Cr6+ content of approximately one-third of the expected value. The range of A/P ratios tested in this study had no effect on the Cr6+ content in the overspray."
1510022,Schilke 2002,Hexavalent Chromium Dissociation from Overspray Particles into Fluid for Three Aircraft Primers,"Master's thesis. iginal document contains color images. d industry use chromate-containing primers extensively to inhibit corrosion on metal assets. Chromate contains Cr6+, a human carcinogen, but there is little epidemiological evidence of increased lung cancer among spray painters. Using bio-aerosol impingers, overspray particles from three primers (solvent-borne epoxy, water-borne epoxy, and solvent-borne polyurethane) were collected into water to test the hypothesis that the paint matrix inhibits Cr6+ release into water, under the premise that this simulates Cr6+ release from particles into lung fluid. Particles were allowed to reside in water for 1 or 24 hours, then separated from the water by centrifugation, and the water tested for Cr6+. The mean fractions of Cr6+ released into the water after 1 and 24 hours for each primer (95% confidence) were: 70 5% and 85 5% (solvent epoxy), 74 4% and 84 4% (water epoxy), and 94 3% and 95 2% (polyurethane). Solvent and water epoxy primer 24-hour Cr6+ release ranged from 100% dissociation to 33% and 48%, respectively. Correlations between Cr6+ distribution with particle size and % Cr6+ dissociated from each sample indicate that particles &amp;lt; 5 mm release a larger fraction of Cr6+ during the first 24 hours vs. particles &amp;gt; 5 micrometers.","Hexavalent Chromium Dissociation from Overspray Particles into Fluid for Three Aircraft Primers Abs: Master's thesis. iginal document contains color images. d industry use chromate-containing primers extensively to inhibit corrosion on metal assets. Chromate contains Cr6+, a human carcinogen, but there is little epidemiological evidence of increased lung cancer among spray painters. Using bio-aerosol impingers, overspray particles from three primers (solvent-borne epoxy, water-borne epoxy, and solvent-borne polyurethane) were collected into water to test the hypothesis that the paint matrix inhibits Cr6+ release into water, under the premise that this simulates Cr6+ release from particles into lung fluid. Particles were allowed to reside in water for 1 or 24 hours, then separated from the water by centrifugation, and the water tested for Cr6+. The mean fractions of Cr6+ released into the water after 1 and 24 hours for each primer (95% confidence) were: 70 5% and 85 5% (solvent epoxy), 74 4% and 84 4% (water epoxy), and 94 3% and 95 2% (polyurethane). Solvent and water epoxy primer 24-hour Cr6+ release ranged from 100% dissociation to 33% and 48%, respectively. Correlations between Cr6+ distribution with particle size and % Cr6+ dissociated from each sample indicate that particles &amp;lt; 5 mm release a larger fraction of Cr6+ during the first 24 hours vs. particles &amp;gt; 5 micrometers."
1510021,Carpenter 2001,Chromate Sampling Methods and Data Analysis,"Final rept. al contains color plates: All DTIC reproductions will be in black and white. jor health issues surrounding occupational exposure to chromates is very well summarized in the National Institute for Occupational Safety and Health (NIOSH) publications. The OSHA Ceiling Standard, 29 CFR 1910. 1000 Table Z-2, for chromic acid and chromate is 1.0 mg/cu m. The ACGIH Standard is more complex, it considers chromates 'Confirmed Human Carcinogens' based upon epidemiological studies. There are two analytical methods typically used when quantifying chromate exposures. The first method is a general metals screen, NIOSH Method 7300. The second method is a specific analysis for hexavalent chrome, NIOSH Method 7600. There are three different calculations depending upon the analytical method used. Methods for reducing chromate exposures follows classical industrial hygiene protocols: Substitution, Engineering, and Administrative controls.","Chromate Sampling Methods and Data Analysis Abs: Final rept. al contains color plates: All DTIC reproductions will be in black and white. jor health issues surrounding occupational exposure to chromates is very well summarized in the National Institute for Occupational Safety and Health (NIOSH) publications. The OSHA Ceiling Standard, 29 CFR 1910. 1000 Table Z-2, for chromic acid and chromate is 1.0 mg/cu m. The ACGIH Standard is more complex, it considers chromates 'Confirmed Human Carcinogens' based upon epidemiological studies. There are two analytical methods typically used when quantifying chromate exposures. The first method is a general metals screen, NIOSH Method 7300. The second method is a specific analysis for hexavalent chrome, NIOSH Method 7600. There are three different calculations depending upon the analytical method used. Methods for reducing chromate exposures follows classical industrial hygiene protocols: Substitution, Engineering, and Administrative controls."
1510020,Placzankis et al. 2001,Examination of Nonchromate Conversion Coatings for Aluminum Armor From Three Final Candidates Using Accelerated Corrosion and Adhesion Test Methods,"Final rept. Nov 1999-Dec 2000. al contains color plates: All DTIC reproductions will be in black and white. tudy examines the effectiveness of three final candidate nonchromate conversion coatings on aluminum alloys 5083, 7039, and 6061 coated with standard solvent-based Chemical Agent Resistant Coating (CARC) system. The nonchromate conversion coatings examined were: Cape Cod Organosilane, Brent Oxsilan AL-0500, and Henkel Alodine 5200. Evaluation methods included: American Society for Testing and Materials (ASTM) standard B117 (ASTM. 'Standard Method of Salt Spray Fog Testing'. ASTM B117, West Conshohocken, PA, 1990) salt fog, General Motors (GM) 9540P (GM. 'Accelerated Corrosion Test; GM 9540P'. GM 9540P, GM Engineering Standards, 1997) cyclic salt spray, ASTM D3359A (ASTM. 'Standard Test Methods for Measuring Adhesion by Tape Test'. ASTM D3359, West Conshohocken, PA, 1987) wet adhesion, ASTM D3359B dry adhesion, ASTM D4541 (ASTM. 'Standard Test Method for Pull-Off Strength of Coated Specimens Subjected to Corrosive Environments'. ASTM D4541, West Conshohocken PA, 1989) pull-off adhesion, and exposure at the U.S. Army Aberdeen Test Center (ATC) automotive test track. Specimens examined consisted of flat test panels as well as actual components used in M2/M3 Bradley Fighting Vehicles Systems. Additional Panels and components were exposed for 4000 mi on actual fielded Bradleys at Camp Roberts, CA, and examined after exposure for degradation and adhesion. The ultimate goal of this study is to choose the best overall substitute for hexavalent chromium based Alodine 1200 which is currently in use and is known to be harmful to the environment and a health hazard.","Examination of Nonchromate Conversion Coatings for Aluminum Armor From Three Final Candidates Using Accelerated Corrosion and Adhesion Test Methods Abs: Final rept. Nov 1999-Dec 2000. al contains color plates: All DTIC reproductions will be in black and white. tudy examines the effectiveness of three final candidate nonchromate conversion coatings on aluminum alloys 5083, 7039, and 6061 coated with standard solvent-based Chemical Agent Resistant Coating (CARC) system. The nonchromate conversion coatings examined were: Cape Cod Organosilane, Brent Oxsilan AL-0500, and Henkel Alodine 5200. Evaluation methods included: American Society for Testing and Materials (ASTM) standard B117 (ASTM. 'Standard Method of Salt Spray Fog Testing'. ASTM B117, West Conshohocken, PA, 1990) salt fog, General Motors (GM) 9540P (GM. 'Accelerated Corrosion Test; GM 9540P'. GM 9540P, GM Engineering Standards, 1997) cyclic salt spray, ASTM D3359A (ASTM. 'Standard Test Methods for Measuring Adhesion by Tape Test'. ASTM D3359, West Conshohocken, PA, 1987) wet adhesion, ASTM D3359B dry adhesion, ASTM D4541 (ASTM. 'Standard Test Method for Pull-Off Strength of Coated Specimens Subjected to Corrosive Environments'. ASTM D4541, West Conshohocken PA, 1989) pull-off adhesion, and exposure at the U.S. Army Aberdeen Test Center (ATC) automotive test track. Specimens examined consisted of flat test panels as well as actual components used in M2/M3 Bradley Fighting Vehicles Systems. Additional Panels and components were exposed for 4000 mi on actual fielded Bradleys at Camp Roberts, CA, and examined after exposure for degradation and adhesion. The ultimate goal of this study is to choose the best overall substitute for hexavalent chromium based Alodine 1200 which is currently in use and is known to be harmful to the environment and a health hazard."
1510019,Kauth 2001,Dissolution of Chromium from Inhalable Primer Paint Particles into a Simulated Lung Fluid,"Master's thesis, Aug 1999-Mar 2001. e of chromate as a corrosion inhibitor in primer paint is an essential component for the protection of aluminum-skinned aircraft and the primary source of hexavalent chromium (Cr (VI)) exposure to USAF aircraft painters. The objective of this research was to quantify the dissolution of chromate from freshly sprayed paint particles into a simulated lung fluid (SLF). Two primer paints were sprayed with a paint spray gun to generate overspray particles for collection into impingers filled with SLF. Particles were allowed to soak in SLF for 24 and 48 hours and then the particles were removed by centrifugation. The remaining Cr (VI) dissolved in the SLF was then compared to the initial Cr (VI) concentration with particles. The results indicate that the dissolution of Cr (VI) into SLF is hindered by the paint. Also, the results indicate that the amount of Cr (VI) dissolved into SLF from the paint particles is not significantly different between the two paints tested or between the 24- and 48-hour resident times. This study suggests that Cr (VI) in paint particles is less bioavailable than Cr (VI) in other articles such as dust or mist.","Dissolution of Chromium from Inhalable Primer Paint Particles into a Simulated Lung Fluid Abs: Master's thesis, Aug 1999-Mar 2001. e of chromate as a corrosion inhibitor in primer paint is an essential component for the protection of aluminum-skinned aircraft and the primary source of hexavalent chromium (Cr (VI)) exposure to USAF aircraft painters. The objective of this research was to quantify the dissolution of chromate from freshly sprayed paint particles into a simulated lung fluid (SLF). Two primer paints were sprayed with a paint spray gun to generate overspray particles for collection into impingers filled with SLF. Particles were allowed to soak in SLF for 24 and 48 hours and then the particles were removed by centrifugation. The remaining Cr (VI) dissolved in the SLF was then compared to the initial Cr (VI) concentration with particles. The results indicate that the dissolution of Cr (VI) into SLF is hindered by the paint. Also, the results indicate that the amount of Cr (VI) dissolved into SLF from the paint particles is not significantly different between the two paints tested or between the 24- and 48-hour resident times. This study suggests that Cr (VI) in paint particles is less bioavailable than Cr (VI) in other articles such as dust or mist."
1510018,Novy 2001,Chromate Content Bias as a Function of Particle Size in Aircraft Primer Paint Overspray,"Master's thesis. painting operations using chromate-containing primer paints produce particles which may expose workers to strontium chromate. Chromate contains hexavalent chromium (Cr(VI)) which is a confirmed human carcinogen. It is suspected that the smaller particles contain disproportionately less Cr(VI) than larger particles. In order to determine if a bias in chromate content exists, paint particles were collected and separated based on particle size and the Cr(VI) concentration was determined. Aviation primer paint from the DeSoto and Deft companies was sprayed in a booth and seven-stage cascade impactors were used to separate particles.","Chromate Content Bias as a Function of Particle Size in Aircraft Primer Paint Overspray Abs: Master's thesis. painting operations using chromate-containing primer paints produce particles which may expose workers to strontium chromate. Chromate contains hexavalent chromium (Cr(VI)) which is a confirmed human carcinogen. It is suspected that the smaller particles contain disproportionately less Cr(VI) than larger particles. In order to determine if a bias in chromate content exists, paint particles were collected and separated based on particle size and the Cr(VI) concentration was determined. Aviation primer paint from the DeSoto and Deft companies was sprayed in a booth and seven-stage cascade impactors were used to separate particles."
1510017,Carlton and  England 2000,Aircraft Corrosion Control: Assessment and Reduction of Chromate Exposures,"Final rept. 1997-2000. rrosion inhibitor of choice in the Air Force is hexavalent chromium (CrVI). CrVI is present in aircraft coating pretreatments as chromic acid and in primers as metallic chromates. Worker exposures to chromate compounds can occur during application of the pretreatment and primer. In addition, depainting (removal of old organic coatings) and mechanical sanding of existing coating systems can release particulates that contain chromates from previously-applied primers. These particulates can also present a CrVI exposure risk. Cr VII compounds have been linked to occupational diseases, specifically dermatitis, nasal irritation, and lung cancer. Water soluble CrVI compounds, such as chromic acid, are confirmed human carcinogens; metallic chromates are considered either confirmed or suspected human carcinogens, depending on the specific metal attached to the chromate. Over the last three years, the industrial Hygiene Branch of the Air Force institute for Environment, Safety and Occupational Health Risk Analysis (AFIERA) collaborated with the Air Force Structural Maintenance community to identify improved methods to reduce CrVIj exposures during corrosion control procedures. We completed a series of field evaluations at Shaw, Cannon, Holloman, Nellis, Hill, Robins, Tinker, and McChord AFBs, and a chromate reduction study at Shaw and Cannon. This technical report summarizes our recommended sampling methodology, data interpretation, and chromate reduction techniques to reduce chromate exposures.","Aircraft Corrosion Control: Assessment and Reduction of Chromate Exposures Abs: Final rept. 1997-2000. rrosion inhibitor of choice in the Air Force is hexavalent chromium (CrVI). CrVI is present in aircraft coating pretreatments as chromic acid and in primers as metallic chromates. Worker exposures to chromate compounds can occur during application of the pretreatment and primer. In addition, depainting (removal of old organic coatings) and mechanical sanding of existing coating systems can release particulates that contain chromates from previously-applied primers. These particulates can also present a CrVI exposure risk. Cr VII compounds have been linked to occupational diseases, specifically dermatitis, nasal irritation, and lung cancer. Water soluble CrVI compounds, such as chromic acid, are confirmed human carcinogens; metallic chromates are considered either confirmed or suspected human carcinogens, depending on the specific metal attached to the chromate. Over the last three years, the industrial Hygiene Branch of the Air Force institute for Environment, Safety and Occupational Health Risk Analysis (AFIERA) collaborated with the Air Force Structural Maintenance community to identify improved methods to reduce CrVIj exposures during corrosion control procedures. We completed a series of field evaluations at Shaw, Cannon, Holloman, Nellis, Hill, Robins, Tinker, and McChord AFBs, and a chromate reduction study at Shaw and Cannon. This technical report summarizes our recommended sampling methodology, data interpretation, and chromate reduction techniques to reduce chromate exposures."
1510016,Carlton et al. 1999,Hexavalent Chromium (CrVI) Field Analytical Method for Bioenvironmental Engineers,"Final rept. dustrial Hygiene Branch, in a collaborative effort with the National Institute for Occupational Safety and Health (NIOSH), developed a field analytical method to measure hexavalent chromium (CrVI, chromate) levels in air. The method uses ultrasonic extraction of sampling filters, solid-phase extraction of chromates from the extracted solution, and determination of chromate concentrations by spectrophotometry. It is an alternative to NIOSH methods 7300 and 7600 and overcomes some of the disadvantages of these methods. The chromate field method is relatively easy to use, specific for CrVI, has a lower detection limit than NIOSH 7600, and allow analysis before there is a chance for significant sample degradation. The method is intended for use by Bioenvironmental Engineers. Although all Bioenvironmental Engineering shops will benefit from use of the method, those shops that take a lot of chromate samples or have significant chromate exposure problems will derive the most benefit from the method.","Hexavalent Chromium (CrVI) Field Analytical Method for Bioenvironmental Engineers Abs: Final rept. dustrial Hygiene Branch, in a collaborative effort with the National Institute for Occupational Safety and Health (NIOSH), developed a field analytical method to measure hexavalent chromium (CrVI, chromate) levels in air. The method uses ultrasonic extraction of sampling filters, solid-phase extraction of chromates from the extracted solution, and determination of chromate concentrations by spectrophotometry. It is an alternative to NIOSH methods 7300 and 7600 and overcomes some of the disadvantages of these methods. The chromate field method is relatively easy to use, specific for CrVI, has a lower detection limit than NIOSH 7600, and allow analysis before there is a chance for significant sample degradation. The method is intended for use by Bioenvironmental Engineers. Although all Bioenvironmental Engineering shops will benefit from use of the method, those shops that take a lot of chromate samples or have significant chromate exposure problems will derive the most benefit from the method."
1510015,Hay et al. 1999,Venturi/Vortex Scrubber Technology for Controlling/Recycling Chromium Electroplating Emissions,"Final rept. um electroplating is an essential DOD process. Chromium has a combination of qualities that are very difficult to substitute, however, the process itself is inefficient, resulting in the production of byproduct gases that rise and create a mist of chromic acid (strongly regulated as an air pollutant) above the plating tank. Venturi/Vortex Scrubber Technology (VVST) was designed to control chromium electroplating emissions by collecting the gas bubbles before they burst at the solution's surface. This project demonstrated the Venturi/Vortex Scrubber Technology at the Marine Corps Logistics Base (MCLB) in Albany, GA. This study concluded that the PLRS was able to reduce the flow rate of the current conventional ventilation system at the one tank chromium electroplating facility at MCLB Albany by 63 percent. If new ventilation and control equipment were to be installed at MCLB Albany, this system would offer a 25 percent reduction in capital costs and a 48 percent reduction in annual costs, representing 36 percent in life-cycle cost savings. This study also presented a strong case for the use of Spark-Induced Breakdown Spectroscopy for monitoring real-time chromium emissions above a chromium electroplating tank.","Venturi/Vortex Scrubber Technology for Controlling/Recycling Chromium Electroplating Emissions Abs: Final rept. um electroplating is an essential DOD process. Chromium has a combination of qualities that are very difficult to substitute, however, the process itself is inefficient, resulting in the production of byproduct gases that rise and create a mist of chromic acid (strongly regulated as an air pollutant) above the plating tank. Venturi/Vortex Scrubber Technology (VVST) was designed to control chromium electroplating emissions by collecting the gas bubbles before they burst at the solution's surface. This project demonstrated the Venturi/Vortex Scrubber Technology at the Marine Corps Logistics Base (MCLB) in Albany, GA. This study concluded that the PLRS was able to reduce the flow rate of the current conventional ventilation system at the one tank chromium electroplating facility at MCLB Albany by 63 percent. If new ventilation and control equipment were to be installed at MCLB Albany, this system would offer a 25 percent reduction in capital costs and a 48 percent reduction in annual costs, representing 36 percent in life-cycle cost savings. This study also presented a strong case for the use of Spark-Induced Breakdown Spectroscopy for monitoring real-time chromium emissions above a chromium electroplating tank."
1510013,Hay et al. 1998,Development of Venturi/Vortex Scrubber Technology for Controlling Chromium Electroplating Hazardous Air Emissions,"Final rept. um has a combination of qualities that give chromium electroplating an important role in coating military hardware and armament. However, chromium electroplating and chromium anodizing operations create hazardous air pollutants in the form of hexavalent chromium. Conventional technologies for controlling this pollutant are expensive, noisy, and use a lot of energy and water. Consequently, an air pollution problem is turned into a water pollution problem that also requires treatment. There is a need for an economical control option that pollutes less than conventional technologies. This project developed control technologies to effectively and economically control hazardous air emissions from Army chromium electroplating and anodizing operations, primarily focusing on the development of the Venturi/Vortex Scrubber technology (VVST).","Development of Venturi/Vortex Scrubber Technology for Controlling Chromium Electroplating Hazardous Air Emissions Abs: Final rept. um has a combination of qualities that give chromium electroplating an important role in coating military hardware and armament. However, chromium electroplating and chromium anodizing operations create hazardous air pollutants in the form of hexavalent chromium. Conventional technologies for controlling this pollutant are expensive, noisy, and use a lot of energy and water. Consequently, an air pollution problem is turned into a water pollution problem that also requires treatment. There is a need for an economical control option that pollutes less than conventional technologies. This project developed control technologies to effectively and economically control hazardous air emissions from Army chromium electroplating and anodizing operations, primarily focusing on the development of the Venturi/Vortex Scrubber technology (VVST)."
1510012,Farmer et al. 1996,Electrosorption of Chromium Ions on Carbon Aerogel Electrodes as a Means of Remediating Ground Water,"An electrically-regenerated separation process has been developed for removing unwanted ions from aqueous waste streams as a minimally-polluting, energy-efficient, and potentially cost-effective alternative to ion exchange, reverse osmosis, electrodialysis, and evaporation. Ground water containing various anions and cations are passed through a stack of carbon aerogel electrodes, each having a very high specific surface area and exceptionally low electrical resistivity. After polarization of the stack, impurity ions are removed from the electrolyte by the imposed electric field and adsorbed on the electrode surfaces. Field tests have shown that hexavalent chromium in the form of HCrO4(-)/CrO42(-)/Cr2O72(-) can be selectively removed from contaminated ground water with a 530 ppm total dissolved solids (TDS) background. The concentration of Cr(VI) can be lowered from 35 to 2 ppb. The mechanism for Cr(VI) separation involves chemisorption on the carbon aerogel anode, a process that can be reversed by cathodic polarization. Cr(VI) removal is not based upon simple double-layer charging.","Electrosorption of Chromium Ions on Carbon Aerogel Electrodes as a Means of Remediating Ground Water Abs: An electrically-regenerated separation process has been developed for removing unwanted ions from aqueous waste streams as a minimally-polluting, energy-efficient, and potentially cost-effective alternative to ion exchange, reverse osmosis, electrodialysis, and evaporation. Ground water containing various anions and cations are passed through a stack of carbon aerogel electrodes, each having a very high specific surface area and exceptionally low electrical resistivity. After polarization of the stack, impurity ions are removed from the electrolyte by the imposed electric field and adsorbed on the electrode surfaces. Field tests have shown that hexavalent chromium in the form of HCrO4(-)/CrO42(-)/Cr2O72(-) can be selectively removed from contaminated ground water with a 530 ppm total dissolved solids (TDS) background. The concentration of Cr(VI) can be lowered from 35 to 2 ppb. The mechanism for Cr(VI) separation involves chemisorption on the carbon aerogel anode, a process that can be reversed by cathodic polarization. Cr(VI) removal is not based upon simple double-layer charging."
1510011,Ingle 1994,Elimination of Chromate Conversion Coatings from Army Tactical Vehicle Manufacturing Processes,"Presented at the Tri-Service Committee on Corrosion Proceedings Held in Orlando, Florida on 21-23 June 1994. nited States Army light tactical vehicles are fabricated from armor-grade aluminum. Aluminum-hulled tactical vehicles are coated with the Army's standard Chemical Agent Resistant Coating (CARC) system. The CARC system includes chemical pretreatments, epoxy primers, and polyurethane topcoats. The MIL-C-5541 chromate conversion coating pretreatment process included in the CARC specification contains hazardous chromic acid. Chromic acid is a SARA Title III extremely hazardous substance and air emissions of the material will be regulated by the 1990 Clean Air Act Amendments. In 1989, Red River Army Depot (RRAD) staff investigated replacing the hazardous chromate conversion coating with a more environmentally acceptable production process. The Army Acquisition Pollution Prevention Support Office reviewed the RRAD results and tasked Ocean City Research Corporation (OCRC) to conduct a comprehensive coating performance assessment and develop appropriate non-chromate production process control documents. The evaluation program demonstrated that chromate conversion coatings may be eliminated from aluminum-hulled tactical vehicle painting operations without degrading overall coating system performance.","Elimination of Chromate Conversion Coatings from Army Tactical Vehicle Manufacturing Processes Abs: Presented at the Tri-Service Committee on Corrosion Proceedings Held in Orlando, Florida on 21-23 June 1994. nited States Army light tactical vehicles are fabricated from armor-grade aluminum. Aluminum-hulled tactical vehicles are coated with the Army's standard Chemical Agent Resistant Coating (CARC) system. The CARC system includes chemical pretreatments, epoxy primers, and polyurethane topcoats. The MIL-C-5541 chromate conversion coating pretreatment process included in the CARC specification contains hazardous chromic acid. Chromic acid is a SARA Title III extremely hazardous substance and air emissions of the material will be regulated by the 1990 Clean Air Act Amendments. In 1989, Red River Army Depot (RRAD) staff investigated replacing the hazardous chromate conversion coating with a more environmentally acceptable production process. The Army Acquisition Pollution Prevention Support Office reviewed the RRAD results and tasked Ocean City Research Corporation (OCRC) to conduct a comprehensive coating performance assessment and develop appropriate non-chromate production process control documents. The evaluation program demonstrated that chromate conversion coatings may be eliminated from aluminum-hulled tactical vehicle painting operations without degrading overall coating system performance."
1510010,Spadafora and  Pepe 1994,"Comparison of Alternatives to Chromic Acid Anodizing, Tri-Service Committee on Corrosion Proceedings Held in Orlando, Florida on June 21-23 1994","Chromic acid anodizing (CAA) is an aluminum surface pretreatment currently used on military aircraft and equipment. Chromium VI, present in this process, is a carcinogen and federal, state and local environmental agencies have implemented legislation which restricts the use of this material. The Naval Air Warfare Center Aircraft Division Warminster investigated several alternatives to CAA including: Sulfuric-Boric Acid Anodize, Sulfuric Acid Anodizing, and Phosphoric Acid Anodizing. Physical performance properties of these processes were characterized and as a result of this program, the MIL-A-8625 anodize specification was modified to include some of these alternatives.","Comparison of Alternatives to Chromic Acid Anodizing, Tri-Service Committee on Corrosion Proceedings Held in Orlando, Florida on June 21-23 1994 Abs: Chromic acid anodizing (CAA) is an aluminum surface pretreatment currently used on military aircraft and equipment. Chromium VI, present in this process, is a carcinogen and federal, state and local environmental agencies have implemented legislation which restricts the use of this material. The Naval Air Warfare Center Aircraft Division Warminster investigated several alternatives to CAA including: Sulfuric-Boric Acid Anodize, Sulfuric Acid Anodizing, and Phosphoric Acid Anodizing. Physical performance properties of these processes were characterized and as a result of this program, the MIL-A-8625 anodize specification was modified to include some of these alternatives."
1510008,Blake 1997,Biotransformation of Toxic Metals by Bacteria,"Final rept. 6 Jan 92-16 Apr 95. ms of this research were to study each of the various molecular mechanisms whereby toxic metal cations and oxyanions are immobilized by bacteria that live in the soil. The research effort focussed on two bacteria: Xanthomonas maltophilia strain OR-02, an organism that chemically transformed individual metals to a less mobile state; and Pseudomonas mendocina strain AS302, a bacterium that formed tight complexes with a wide variety of toxic metal ions. The NADPH-dependent reduction of Hg(II) to elemental mercury by OR-02 was catalyzed by an inducible mercuric reductase. The reduction of selenite and tellurite to their insoluble elemental forms was mediated by an intracellular glutathione reductase that utilized the spontaneously-formed bis(glutathio)Se or bis(glutathio)Te, respectively, as pseudosubstrates. The 3-electron reduction of hexavalent chromium was catalyzed by a membrane-bound chromate reductase. A total of 14 different heavy metal ions were shown to bind tightly to strain AS302 with biosorption capacities that ranged from 320 (Pb) to 680 (Ag) mu-mol metal/g dry cell weight. This project could provide useful information toward the eventual exploitation of these organisms for the removal of toxic metal wastes from selected, heavily polluted sites.","Biotransformation of Toxic Metals by Bacteria Abs: Final rept. 6 Jan 92-16 Apr 95. ms of this research were to study each of the various molecular mechanisms whereby toxic metal cations and oxyanions are immobilized by bacteria that live in the soil. The research effort focussed on two bacteria: Xanthomonas maltophilia strain OR-02, an organism that chemically transformed individual metals to a less mobile state; and Pseudomonas mendocina strain AS302, a bacterium that formed tight complexes with a wide variety of toxic metal ions. The NADPH-dependent reduction of Hg(II) to elemental mercury by OR-02 was catalyzed by an inducible mercuric reductase. The reduction of selenite and tellurite to their insoluble elemental forms was mediated by an intracellular glutathione reductase that utilized the spontaneously-formed bis(glutathio)Se or bis(glutathio)Te, respectively, as pseudosubstrates. The 3-electron reduction of hexavalent chromium was catalyzed by a membrane-bound chromate reductase. A total of 14 different heavy metal ions were shown to bind tightly to strain AS302 with biosorption capacities that ranged from 320 (Pb) to 680 (Ag) mu-mol metal/g dry cell weight. This project could provide useful information toward the eventual exploitation of these organisms for the removal of toxic metal wastes from selected, heavily polluted sites."
1510007,Cohen and  Spadafora 1995,Comparison of Thin Film Sulfuric Acid Anodizing and Chromic Acid Anodizing Processes,"Final rept. Oct 93-Apr 95. c acid anodizing (CAA), a common aluminum pretreatment, forms a thick oxide film which provides protection against environmental degradation. Chromium VI, however, is a carcinogen and its widespread use as a corrosion inhibitor is being restricted. The Navy has targeted chromated maintenance operations for reduction of hazardous waste generation. Alternative anodize processes include: Phosphoric Acid Anodizing, Boeing Aerospace Corp's Boric-Sulfuric Acid Anodize and thin film sulfuric acid anodizing (TFSAA). This report describes an investigation on the performance properties of TFSAA and CAA both sealed and unsealed on various substrates with and without standard Navy coating systems. At specific coating weights, TFSAA could effectively provide equivalent corrosion resistance and paint adhesion as compared to CAA. Replacement of CAA eliminates the need for expensive control equipment required under the Clean Air Act, resulting in $M's in cost avoidance for the Navy. jg p.3.","Comparison of Thin Film Sulfuric Acid Anodizing and Chromic Acid Anodizing Processes Abs: Final rept. Oct 93-Apr 95. c acid anodizing (CAA), a common aluminum pretreatment, forms a thick oxide film which provides protection against environmental degradation. Chromium VI, however, is a carcinogen and its widespread use as a corrosion inhibitor is being restricted. The Navy has targeted chromated maintenance operations for reduction of hazardous waste generation. Alternative anodize processes include: Phosphoric Acid Anodizing, Boeing Aerospace Corp's Boric-Sulfuric Acid Anodize and thin film sulfuric acid anodizing (TFSAA). This report describes an investigation on the performance properties of TFSAA and CAA both sealed and unsealed on various substrates with and without standard Navy coating systems. At specific coating weights, TFSAA could effectively provide equivalent corrosion resistance and paint adhesion as compared to CAA. Replacement of CAA eliminates the need for expensive control equipment required under the Clean Air Act, resulting in $M's in cost avoidance for the Navy. jg p.3."
1510005,Spadafora and  Pepe 1993,Comparison of Sulfuric Acid/Boric Acid Anodize and Chromic Acid Anodize Processes,"Final rept. Mar 92-Jun 93. c acid anodizing (CAA) is an aluminum surface pretreatment currently used on Navy aircraft and weapon systems. This anodize process forms a thick oxide film which provides protection against environmental degradation. This is particularly important due to the severely corrosive naval aviation operational environment. Chromium VI, however, is a carcinogen and its wide spread use as a corrosion inhibitor in this process is being restricted. The Navy has targeted chromated maintenance operations for reduction of hazardous waste generation. Several alternative candidates have been identified: Phosphoric Acid Anodizing, Boeing Aerospace Corp.'s Boric-Sulfuric Acid Anodize (SBAA) and thin film sulfuric acid anodizing. The Boeing SBAA process was selected for optimization and service demonstration. The Naval Air Warfare Center Aircraft Division Warminster analyzed the performance properties of SBAA and CAA both sealed and unsealed on various substrates with and without standard Navy coatings. Surface pretreatments, Anodic films, Environmentally complaint materials, Organic coatings.","Comparison of Sulfuric Acid/Boric Acid Anodize and Chromic Acid Anodize Processes Abs: Final rept. Mar 92-Jun 93. c acid anodizing (CAA) is an aluminum surface pretreatment currently used on Navy aircraft and weapon systems. This anodize process forms a thick oxide film which provides protection against environmental degradation. This is particularly important due to the severely corrosive naval aviation operational environment. Chromium VI, however, is a carcinogen and its wide spread use as a corrosion inhibitor in this process is being restricted. The Navy has targeted chromated maintenance operations for reduction of hazardous waste generation. Several alternative candidates have been identified: Phosphoric Acid Anodizing, Boeing Aerospace Corp.'s Boric-Sulfuric Acid Anodize (SBAA) and thin film sulfuric acid anodizing. The Boeing SBAA process was selected for optimization and service demonstration. The Naval Air Warfare Center Aircraft Division Warminster analyzed the performance properties of SBAA and CAA both sealed and unsealed on various substrates with and without standard Navy coatings. Surface pretreatments, Anodic films, Environmentally complaint materials, Organic coatings."
1510004,Emeric and  Miller 1992,Surface Preparation of Stainless Steel Prior to Painting,"Final rept. Jan-Sep 92. ry specification MIL-T-704, Treatment and paint of materiel, requires the passivation of corrosion-resisting steel surfaces before painting. It also states surfaces to be painted shall be treated with wash primer conforming to DOD-P-15328, Primer (wash) pretreatment (Formula No. 117 for metals), metric, or MIL-C-8514, Coating compound, metal pretreatment, resin-acid. Federal, state and city environmental and/or health regulations may prohibit the use of hexavalent chromium-one of the components of the passivating formulation used for the treatment of corrosion-resisting steels. Many companies are not passivating the corrosion-resisting steels before the application of wash primer. Based on the above, we started a laboratory investigation to determine if the elimination of the passivating procedure will have an adverse effect on the camouflage paint system. From the information obtained, it is recommended that consideration be given to the elimination of the passivation requirement for stainless steel. It is also recommended that more extensive work be conducted to verify these findings.","Surface Preparation of Stainless Steel Prior to Painting Abs: Final rept. Jan-Sep 92. ry specification MIL-T-704, Treatment and paint of materiel, requires the passivation of corrosion-resisting steel surfaces before painting. It also states surfaces to be painted shall be treated with wash primer conforming to DOD-P-15328, Primer (wash) pretreatment (Formula No. 117 for metals), metric, or MIL-C-8514, Coating compound, metal pretreatment, resin-acid. Federal, state and city environmental and/or health regulations may prohibit the use of hexavalent chromium-one of the components of the passivating formulation used for the treatment of corrosion-resisting steels. Many companies are not passivating the corrosion-resisting steels before the application of wash primer. Based on the above, we started a laboratory investigation to determine if the elimination of the passivating procedure will have an adverse effect on the camouflage paint system. From the information obtained, it is recommended that consideration be given to the elimination of the passivation requirement for stainless steel. It is also recommended that more extensive work be conducted to verify these findings."
1510002,Prentice et al. 1992,Electrochemical Removal of Chromium from Wastewater,"Rept. for 20 Jul 91-19 May 92. ried out a study to determine the feasibility of electrochemically removing chromium from plating wastewater. Hexavalent chromium is a carcinogen and its discharge is required to be near 1 ppm. In our work we determined the effects of key variables including temperature, electrolyte flow rate, pH, and electrode composition. At the low chromium concentrations found in plating wastewater, we determined that the rate of chromium ion removal was mass transfer limited. Of the four electrode types tested, only gold gave significantly enhanced performance; however, graphite would probably be the most cost-effective for large-scale application. Chromium reduction rate was significantly increased at reduced pH. Because chromium ion solubility increases at lower pH, the higher removal rate would need to to be balanced against higher chromium redissolution rate in a practical system. A preliminary analysis based on our laboratory data indicates that a practical system based on electrochemical technology is feasible. WASTEWATER TREATMENT, CHROMIUM, ELECTROCHEMICAL PROCESS.","Electrochemical Removal of Chromium from Wastewater Abs: Rept. for 20 Jul 91-19 May 92. ried out a study to determine the feasibility of electrochemically removing chromium from plating wastewater. Hexavalent chromium is a carcinogen and its discharge is required to be near 1 ppm. In our work we determined the effects of key variables including temperature, electrolyte flow rate, pH, and electrode composition. At the low chromium concentrations found in plating wastewater, we determined that the rate of chromium ion removal was mass transfer limited. Of the four electrode types tested, only gold gave significantly enhanced performance; however, graphite would probably be the most cost-effective for large-scale application. Chromium reduction rate was significantly increased at reduced pH. Because chromium ion solubility increases at lower pH, the higher removal rate would need to to be balanced against higher chromium redissolution rate in a practical system. A preliminary analysis based on our laboratory data indicates that a practical system based on electrochemical technology is feasible. WASTEWATER TREATMENT, CHROMIUM, ELECTROCHEMICAL PROCESS."
1510001,Blake 1992,Transformation and Precipitation of Toxic Metals by Pseudomonas Maltophilia,"Final rept. 1 May 89-31 Apr 92. ms of this research were to study each of the various molecular mechanisms whereby toxic metal cations and oxyanions were chemically transformed by Pseudomonas maltophilia strain OR02. The research effort focused on the microbial-dependent transformations of mercury, selenium, tellurium, chromium, lead, cadmium, silver, and gold. The NADPH-dependent reduction of Hg(II) was catalyzed by an inducible mercuric reductase. The reduction of selenite and tellurite to their insoluble elemental forms was mediated by an intracellular glutathione reductase that utilized the spontaneously-formed bis(glutathio)Se or bis(glutathio)Te, respectively, as pseudosubstrates. The 3-electron reduction of hexavalent chromium was catalyzed by a membrane-bound chromate reductase. The enzymatic basis for the transformation and immobilization of soluble lead(II), cadmium(II), silver(I), and gold(III) was not immediately apparent. This project could provide useful information toward the eventual exploitation of P. maltophilia and related organisms for the removal of toxic metal wastes from selected, heavily polluted sites. Bioremediation, Mercury, Selenium, Chromate Lead.","Transformation and Precipitation of Toxic Metals by Pseudomonas Maltophilia Abs: Final rept. 1 May 89-31 Apr 92. ms of this research were to study each of the various molecular mechanisms whereby toxic metal cations and oxyanions were chemically transformed by Pseudomonas maltophilia strain OR02. The research effort focused on the microbial-dependent transformations of mercury, selenium, tellurium, chromium, lead, cadmium, silver, and gold. The NADPH-dependent reduction of Hg(II) was catalyzed by an inducible mercuric reductase. The reduction of selenite and tellurite to their insoluble elemental forms was mediated by an intracellular glutathione reductase that utilized the spontaneously-formed bis(glutathio)Se or bis(glutathio)Te, respectively, as pseudosubstrates. The 3-electron reduction of hexavalent chromium was catalyzed by a membrane-bound chromate reductase. The enzymatic basis for the transformation and immobilization of soluble lead(II), cadmium(II), silver(I), and gold(III) was not immediately apparent. This project could provide useful information toward the eventual exploitation of P. maltophilia and related organisms for the removal of toxic metal wastes from selected, heavily polluted sites. Bioremediation, Mercury, Selenium, Chromate Lead."
1510000,Munns et al. 1991,"Marine Ecological Risk Assessment at Naval Construction Battalion Center, Davisville, Rhode Island. Phase 1","Final rept. Sep 88-Jun 89. ed in collaboration with Science Applications International Corporation. val Construction Battalion Center (NCBC) in Davisville, Rhode Island, has been the subject of a joint ecological research program by the Navy and Environmental Protection Agency. Allen Harbor, a small embayment of Narragansett Bay adjacent to NCBC, was used to develop research and monitoring methods for ecological risk assessment. Two sites on the National Priorities List were of particular concern: (1) a 15-acre landfill used from 1946 to 1972 for the disposal of such wastes as solvents, PCB-contaminated oils, preservatives, sewage sludge, chromic acid, and construction rubble; and (2) a cement-lined pit that from 1960 to 1974 was the depository of calcium hypochlorite, chloride, and decontaminating solution. Phase I of the study characterizes the ecology, natural resources, sediment, and water quality. A preliminary ecological risk assessment is developed. Exposure to and the effects of contamination are measured at both subtidal and intertidal stations. A T-shaped transect of stations projecting from the mouth of the harbor into Narragansett Bay proper is established to determine if measurable levels of contaminants and effects are reaching the Bay. A series of mid-Narragansett Bay stations provide a reference for comparing effects within Allen Harbor.","Marine Ecological Risk Assessment at Naval Construction Battalion Center, Davisville, Rhode Island. Phase 1 Abs: Final rept. Sep 88-Jun 89. ed in collaboration with Science Applications International Corporation. val Construction Battalion Center (NCBC) in Davisville, Rhode Island, has been the subject of a joint ecological research program by the Navy and Environmental Protection Agency. Allen Harbor, a small embayment of Narragansett Bay adjacent to NCBC, was used to develop research and monitoring methods for ecological risk assessment. Two sites on the National Priorities List were of particular concern: (1) a 15-acre landfill used from 1946 to 1972 for the disposal of such wastes as solvents, PCB-contaminated oils, preservatives, sewage sludge, chromic acid, and construction rubble; and (2) a cement-lined pit that from 1960 to 1974 was the depository of calcium hypochlorite, chloride, and decontaminating solution. Phase I of the study characterizes the ecology, natural resources, sediment, and water quality. A preliminary ecological risk assessment is developed. Exposure to and the effects of contamination are measured at both subtidal and intertidal stations. A T-shaped transect of stations projecting from the mouth of the harbor into Narragansett Bay proper is established to determine if measurable levels of contaminants and effects are reaching the Bay. A series of mid-Narragansett Bay stations provide a reference for comparing effects within Allen Harbor."
1509999,Sommer 1991,Removal of Copper and Iron Contamination from Chromic Acid Electroplating Baths Using Electrodialysis with Caustic Catholyte,"Master's thesis. ficiency and kinetics of the removal of copper and iron contamination from a chromic acid plating bath were evaluated using a proprietary electrodialytic purification unit with caustic catholyte. The unit consisted of an anode compartment and a cathode compartment separated by a cation-specific membrane. The proprietary electrodes in each compartment were connected to a constant amperage, variable voltage power supply. By design, multivalent metal cations were electrotransported through the membrane and converted into insoluble hydroxides upon reaction with cathode formed hydroxyl ions and other insolubilizing agents present in the proprietary catholyte solution. Threshold Contaminant Levels (TCLs) were approximated using the Hull Cell test apparatus and sample metal concentrations were measured using atomic absorption spectrophotometry.","Removal of Copper and Iron Contamination from Chromic Acid Electroplating Baths Using Electrodialysis with Caustic Catholyte Abs: Master's thesis. ficiency and kinetics of the removal of copper and iron contamination from a chromic acid plating bath were evaluated using a proprietary electrodialytic purification unit with caustic catholyte. The unit consisted of an anode compartment and a cathode compartment separated by a cation-specific membrane. The proprietary electrodes in each compartment were connected to a constant amperage, variable voltage power supply. By design, multivalent metal cations were electrotransported through the membrane and converted into insoluble hydroxides upon reaction with cathode formed hydroxyl ions and other insolubilizing agents present in the proprietary catholyte solution. Threshold Contaminant Levels (TCLs) were approximated using the Hull Cell test apparatus and sample metal concentrations were measured using atomic absorption spectrophotometry."
1509998,Davis 1991,Evaluation of Electrodialysis for Chronic Acid Recovery and Purification at Corpus Christi Army Depot,"Final rept. Oct 89-Apr 91. e quantity of hazardous waste is generated during the maintenance, repair, and overhaul of a wide variety of military equipment at Army depots. Some of this waste is generated by the use of chromic acid solutions for chromium electroplating and the application and removal of chromate conversion coatings. Hazardous waste results when metal contamination builds up in the solutions to such a degree that the solutions must be disposed of as hazardous waste. Removal of this metal contamination should result in a lengthened bath life and reduced hazardous wate generation. As part of its pollution abatement and environmental control mission, the U.S. Army Toxic and Hazardous Materials Agency (USATHAMA) is pursuing R and D projects to assist depots in meeting the Army goal of a 50 percent reduction in hazardous waste by the end of 1992 compared with 1985 baseline levels. In one project, USATHAMA purchased, installed, operated, and evaluated an electrodialysis system on two chromic acid process solutions at Corpus Christi Army Depot (CCAD) in Corpus Christi, Texas. The objective of this task was to evaluate the system's ability to remove metal contamination and oxidize trivalent chromium (an impurity) to hexavalent chromium (chromic acid).","Evaluation of Electrodialysis for Chronic Acid Recovery and Purification at Corpus Christi Army Depot Abs: Final rept. Oct 89-Apr 91. e quantity of hazardous waste is generated during the maintenance, repair, and overhaul of a wide variety of military equipment at Army depots. Some of this waste is generated by the use of chromic acid solutions for chromium electroplating and the application and removal of chromate conversion coatings. Hazardous waste results when metal contamination builds up in the solutions to such a degree that the solutions must be disposed of as hazardous waste. Removal of this metal contamination should result in a lengthened bath life and reduced hazardous wate generation. As part of its pollution abatement and environmental control mission, the U.S. Army Toxic and Hazardous Materials Agency (USATHAMA) is pursuing R and D projects to assist depots in meeting the Army goal of a 50 percent reduction in hazardous waste by the end of 1992 compared with 1985 baseline levels. In one project, USATHAMA purchased, installed, operated, and evaluated an electrodialysis system on two chromic acid process solutions at Corpus Christi Army Depot (CCAD) in Corpus Christi, Texas. The objective of this task was to evaluate the system's ability to remove metal contamination and oxidize trivalent chromium (an impurity) to hexavalent chromium (chromic acid)."
1509997,Hedgecock 1990,"Hexavalent Chromium Reduction Pretreatment Process Evaluation, Randolph AFB, Texas",Final rept. for period ending 11 May 90. ope of this survey was to evaluate an experimental in-situ chromium reduction process. The objective was to determine if base personnel could safely and effectively treat chromium waste so that it would no longer be considered a hazardous waste. Recommendations include: (1) Obtain approval from TWC to perform the pretreatment process; (2) Perform cyanide removal on each drum of waste; (3) Do not mix the precipitate back into solution before discharging the wastewater to the sanitary sewer; (4) Sample and analyze the sludge for hexavalent chromium; (5) Sample an appropriate percentage of the drums to ensure the process routinely works; (6) Pretreatment personnel should always wear protective clothing. (TTL),"Hexavalent Chromium Reduction Pretreatment Process Evaluation, Randolph AFB, Texas Abs: Final rept. for period ending 11 May 90. ope of this survey was to evaluate an experimental in-situ chromium reduction process. The objective was to determine if base personnel could safely and effectively treat chromium waste so that it would no longer be considered a hazardous waste. Recommendations include: (1) Obtain approval from TWC to perform the pretreatment process; (2) Perform cyanide removal on each drum of waste; (3) Do not mix the precipitate back into solution before discharging the wastewater to the sanitary sewer; (4) Sample and analyze the sludge for hexavalent chromium; (5) Sample an appropriate percentage of the drums to ensure the process routinely works; (6) Pretreatment personnel should always wear protective clothing. (TTL)"
1509995,Rao et al. 2013,Removal of hexavalent chromium ions by Yarrowia lipolytica cells modified with phyto-inspired Fe(0)/Fe(3)O(4) nanoparticles,"The removal of hexavalent chromium [Cr (VI)], an important ground water pollutant by phyto-inspired Fe(0)/Fe(3)O(4) nanocomposite-modified cells of Yarrowia lipolytica (NCIM 3589 and NCIM 3590), was investigated. Electron microscopy and magnetometer studies indicated an effective modification of yeast cell surfaces by the nanocomposites. The effect of pH, temperature, agitation speed, contact time and initial metal ion concentration on the removal of Cr (VI) was determined. The specific uptake values at pH 2.0 were 186.32±3.17 and 137.31±4.53mgg(-1) for NCIM 3589 and NCIM 3590, respectively, when 1000mgL(-1) of metal ion concentrations were used. The equilibrium data fitted to Scatchard, Langmuir and linearized Freundlich models suggesting that adsorption played a role in the removal of Cr (VI) ions. The surface modified yeast cells displayed higher values of Langmuir and Scatchard coefficients than the unmodified cells indicating that the former were more efficient in Cr (VI) removal. The enhanced detoxification of Cr (VI) ions by this composite material could be attributed to the reductive power of the Fe(0)/Fe(3)O(4) nanocomposites as well the yeast cell surface functional groups.","Removal of hexavalent chromium ions by Yarrowia lipolytica cells modified with phyto-inspired Fe(0)/Fe(3)O(4) nanoparticles Abs: The removal of hexavalent chromium [Cr (VI)], an important ground water pollutant by phyto-inspired Fe(0)/Fe(3)O(4) nanocomposite-modified cells of Yarrowia lipolytica (NCIM 3589 and NCIM 3590), was investigated. Electron microscopy and magnetometer studies indicated an effective modification of yeast cell surfaces by the nanocomposites. The effect of pH, temperature, agitation speed, contact time and initial metal ion concentration on the removal of Cr (VI) was determined. The specific uptake values at pH 2.0 were 186.32±3.17 and 137.31±4.53mgg(-1) for NCIM 3589 and NCIM 3590, respectively, when 1000mgL(-1) of metal ion concentrations were used. The equilibrium data fitted to Scatchard, Langmuir and linearized Freundlich models suggesting that adsorption played a role in the removal of Cr (VI) ions. The surface modified yeast cells displayed higher values of Langmuir and Scatchard coefficients than the unmodified cells indicating that the former were more efficient in Cr (VI) removal. The enhanced detoxification of Cr (VI) ions by this composite material could be attributed to the reductive power of the Fe(0)/Fe(3)O(4) nanocomposites as well the yeast cell surface functional groups."
1509994,Singha et al. 2013,Functionalized granular activated carbon and surface complexation with chromates and bi-chromates in wastewater,"Cr(VI) is present in the aqueous medium as chromate (CrO) and bi-chromate (HCrO). Functionalized granular activated carbons (FACs) are used as adsorbents in the treatment of wastewaters containing hexavalent chromium. The FACs are prepared by chemical modifications of granular activated carbons (GACs) using functionalizing agents like HNO, HCl and HF. The Brunauer, Emmett and Teller surface areas of FAC-HCl (693.5m/g), FAC-HNO (648.8m/g) and FAC-HF (726.2m/g) are comparable to the GAC (777.7m/g). But, the adsorption capacity of each of the FAC-HNO, FAC-HCl and FAC-HF is found to be higher than the GAC. The functional groups play an important role in the adsorption process and pH has practically no role in this specific case. The FACs have hydrophilic protonated external surfaces in particular, along with the functional surface sites capable to make complexes with the CrO and HCrO present. Surface complex formation is maximized in the order FAC-HNO&gt;FAC-HF&gt;FAC-HCl, in proportion to the total surface acidity. This is also confirmed by the well-known pseudo second-order kinetic model. Physi-sorption equilibrium isotherms are parameterized by using standard Freundlich and Langmuir models. Langmuir fits better. The formation of surface complexes with the functional groups and hexavalent chromium is also revealed in the images of field emission scanning electron micrograph; energy dispersive X-ray spectroscopy and Fourier transform infrared spectroscopy analysis after adsorption. The intra-particle diffusion is not the only rate-controlling factor. The Boyd's film diffusion model fits very well with R as high as 98.1% for FAC-HNO. This result demonstrates that the functionalization of the GAC by acid treatments would increase the diffusion rate, predominantly with a boundary layer diffusion effect.","Functionalized granular activated carbon and surface complexation with chromates and bi-chromates in wastewater Abs: Cr(VI) is present in the aqueous medium as chromate (CrO) and bi-chromate (HCrO). Functionalized granular activated carbons (FACs) are used as adsorbents in the treatment of wastewaters containing hexavalent chromium. The FACs are prepared by chemical modifications of granular activated carbons (GACs) using functionalizing agents like HNO, HCl and HF. The Brunauer, Emmett and Teller surface areas of FAC-HCl (693.5m/g), FAC-HNO (648.8m/g) and FAC-HF (726.2m/g) are comparable to the GAC (777.7m/g). But, the adsorption capacity of each of the FAC-HNO, FAC-HCl and FAC-HF is found to be higher than the GAC. The functional groups play an important role in the adsorption process and pH has practically no role in this specific case. The FACs have hydrophilic protonated external surfaces in particular, along with the functional surface sites capable to make complexes with the CrO and HCrO present. Surface complex formation is maximized in the order FAC-HNO&gt;FAC-HF&gt;FAC-HCl, in proportion to the total surface acidity. This is also confirmed by the well-known pseudo second-order kinetic model. Physi-sorption equilibrium isotherms are parameterized by using standard Freundlich and Langmuir models. Langmuir fits better. The formation of surface complexes with the functional groups and hexavalent chromium is also revealed in the images of field emission scanning electron micrograph; energy dispersive X-ray spectroscopy and Fourier transform infrared spectroscopy analysis after adsorption. The intra-particle diffusion is not the only rate-controlling factor. The Boyd's film diffusion model fits very well with R as high as 98.1% for FAC-HNO. This result demonstrates that the functionalization of the GAC by acid treatments would increase the diffusion rate, predominantly with a boundary layer diffusion effect."
1509993,Lou et al. 2013,DNA damage and oxidative stress in human B lymphoblastoid cells after combined exposure to hexavalent chromium and nickel compounds,"In the present study, human B lymphoblastoid cells were exposed to potassium dichromate and/or nickel chloride for 24h or 48h. The cell viability and DNA damage induced by these compounds was measured with the CCK-8 assay and Comet assay, respectively. In addition, the generation of reactive oxygen species (ROS) and the levels of malondialdehyde (MDA) were measured using commercially available kits. Our results indicated that potassium dichromate could decrease cell viability and induce DNA damage in human B lymphoblastoid cells in a time - and concentration - dependent manner, but the toxicity of nickel chloride was not so obvious at concentrations used in our study. The results of ROS showed that both two compounds could only induce weak elevation of ROS level, but MDA levels were significantly enhanced. Antagonistic effects of cytotoxicity were mainly found between Cr (VI) and Ni (II), and synergistic effects of DNA damage and oxidative stress were partially found between these two compounds. Moreover, there were good correlations between the results of comet assay and the results of oxidative stress assays. It is suggested that synergistic DNA damage induced by simultaneously exposure of hexavalent chromium and nickel compounds is possibly related to oxidative stress.","DNA damage and oxidative stress in human B lymphoblastoid cells after combined exposure to hexavalent chromium and nickel compounds Abs: In the present study, human B lymphoblastoid cells were exposed to potassium dichromate and/or nickel chloride for 24h or 48h. The cell viability and DNA damage induced by these compounds was measured with the CCK-8 assay and Comet assay, respectively. In addition, the generation of reactive oxygen species (ROS) and the levels of malondialdehyde (MDA) were measured using commercially available kits. Our results indicated that potassium dichromate could decrease cell viability and induce DNA damage in human B lymphoblastoid cells in a time - and concentration - dependent manner, but the toxicity of nickel chloride was not so obvious at concentrations used in our study. The results of ROS showed that both two compounds could only induce weak elevation of ROS level, but MDA levels were significantly enhanced. Antagonistic effects of cytotoxicity were mainly found between Cr (VI) and Ni (II), and synergistic effects of DNA damage and oxidative stress were partially found between these two compounds. Moreover, there were good correlations between the results of comet assay and the results of oxidative stress assays. It is suggested that synergistic DNA damage induced by simultaneously exposure of hexavalent chromium and nickel compounds is possibly related to oxidative stress."
1509992,Fuoco et al. ,Response to metal stress of Nicotiana langsdorffii plants wild-type and transgenic for the rat glucocorticoid receptor gene,"Recently our findings have shown that the integration of the gene coding for the rat gluco-corticoid receptor (GR receptor) in Nicotiana langsdorffii plants induced morphophysiological effects in transgenic plants through the modification of their hormonal pattern. Phytohormones play a key role in plant responses to many different biotic and abiotic stresses since a modified hormonal profile up-regulates the activation of secondary metabolites involved in the response to stress. In this work transgenic GR plants and isogenic wild type genotypes were exposed to metal stress by treating them with 30ppm cadmium(II) or 50ppm chromium(VI). Hormonal patterns along with changes in key response related metabolites were then monitored and compared. Heavy metal up-take was found to be lower in the GR plants. The transgenic plants exhibited higher values of S-abscisic acid (S-ABA) and 3-indole acetic acid (IAA), salicylic acid and total polyphenols, chlorogenic acid and antiradical activity, compared to the untransformed wild type plants. Both Cd and Cr treatments led to an increase in hormone concentrations and secondary metabolites only in wild type plants. Analysis of the results suggests that the stress responses due to changes in the plant's hormonal system may derive from the interaction between the GR receptor and phytosteroids, which are known to play a key role in plant physiology and development.","Response to metal stress of Nicotiana langsdorffii plants wild-type and transgenic for the rat glucocorticoid receptor gene Abs: Recently our findings have shown that the integration of the gene coding for the rat gluco-corticoid receptor (GR receptor) in Nicotiana langsdorffii plants induced morphophysiological effects in transgenic plants through the modification of their hormonal pattern. Phytohormones play a key role in plant responses to many different biotic and abiotic stresses since a modified hormonal profile up-regulates the activation of secondary metabolites involved in the response to stress. In this work transgenic GR plants and isogenic wild type genotypes were exposed to metal stress by treating them with 30ppm cadmium(II) or 50ppm chromium(VI). Hormonal patterns along with changes in key response related metabolites were then monitored and compared. Heavy metal up-take was found to be lower in the GR plants. The transgenic plants exhibited higher values of S-abscisic acid (S-ABA) and 3-indole acetic acid (IAA), salicylic acid and total polyphenols, chlorogenic acid and antiradical activity, compared to the untransformed wild type plants. Both Cd and Cr treatments led to an increase in hormone concentrations and secondary metabolites only in wild type plants. Analysis of the results suggests that the stress responses due to changes in the plant's hormonal system may derive from the interaction between the GR receptor and phytosteroids, which are known to play a key role in plant physiology and development."
1509991,Tikare et al. 2012,Effect of garlic (Allium sativum) on hematology and erythrocyte antioxidant defense system of albino rats exposed to heavy metals (nickel II &amp; chromium VI),"Heavy metals are stable environmental contaminants, causing various alterations in target tissues. Garlic has some beneficial effect in preventing heavy metal induced various alteration. The objective was to investigate the possible protective role of fresh aqueous homogenate of garlic on hematology, erythrocyte antioxidant defense system in male albino rats treated with NiSO4 and K2Cr2O7. Rats were divided into six groups. Group I was untreated control. Group II was given aqueous homogenate of garlic (orally). Group III was administered with nickel sulfate (i.p). Group IV was given NiSO4 and garlic simultaneously. Group V was administered with K2Cr2O7 (i.p). Group VI were treated simultaneously with K2Cr2O7 and garlic. RBC, WBC, platelet count, PCV%, hemoglobin concentration decreased significantly and clotting time increased significantly after nickel treatment. After chromium treatment all the values decreased except clotting time. Increased malondialdehyde and glutathione level after nickel and chromium treatment was observed. Also erythrocyte superoxide dismutase, glutathione peroxidase and catalase activities significantly increased after nickel and chromium treatment. Simultaneous garlic supplementation exhibited protective role to combat nickel toxicity, whereas no such beneficial effects were observed for chromium (VI). Garlic may partially prevent nickel and chromium induced alteration but such ameliorated effects as an antioxidant is only restricted on nickel induced alteration.","Effect of garlic (Allium sativum) on hematology and erythrocyte antioxidant defense system of albino rats exposed to heavy metals (nickel II &amp; chromium VI) Abs: Heavy metals are stable environmental contaminants, causing various alterations in target tissues. Garlic has some beneficial effect in preventing heavy metal induced various alteration. The objective was to investigate the possible protective role of fresh aqueous homogenate of garlic on hematology, erythrocyte antioxidant defense system in male albino rats treated with NiSO4 and K2Cr2O7. Rats were divided into six groups. Group I was untreated control. Group II was given aqueous homogenate of garlic (orally). Group III was administered with nickel sulfate (i.p). Group IV was given NiSO4 and garlic simultaneously. Group V was administered with K2Cr2O7 (i.p). Group VI were treated simultaneously with K2Cr2O7 and garlic. RBC, WBC, platelet count, PCV%, hemoglobin concentration decreased significantly and clotting time increased significantly after nickel treatment. After chromium treatment all the values decreased except clotting time. Increased malondialdehyde and glutathione level after nickel and chromium treatment was observed. Also erythrocyte superoxide dismutase, glutathione peroxidase and catalase activities significantly increased after nickel and chromium treatment. Simultaneous garlic supplementation exhibited protective role to combat nickel toxicity, whereas no such beneficial effects were observed for chromium (VI). Garlic may partially prevent nickel and chromium induced alteration but such ameliorated effects as an antioxidant is only restricted on nickel induced alteration."
1509990,Hsu et al. 2013,Enhanced photocatalytic activity of chromium(VI) reduction and EDTA oxidization by photoelectrocatalysis combining cationic exchange membrane processes,"A novel technology of photoelectrocatalysis (PEC) combining with cationic exchange membrane (CEM) was proposed for simultaneous reduction of chromium(VI) and oxidization of EDTA. The application of CEM was used to enhance the efficiency for prevention of the re-oxidation of reduced chromium with the electron-hole pairs. In this study, effects of current density, pH, TiO dosage, hydraulic retention time (HRT), light intensity and EDTA/Cr(VI) molar ratio were all investigated. The results showed that the optimum conversion efficiency occurred at 4mA/cm with the presence of CEM. Higher conversion efficiencies were observed at lower pH due to the electrostatic attractions between positive charged TiOH, and negatively charged Cr(VI) and EDTA. The optimum TiO loading of 1g/L was depended mainly on the acidic pH range, especially at higher HRT and irradiation intensity. In addition, higher EDTA/Cr(VI) molar ratio enhanced the reduction efficiency of Cr(VI), indicating EDTA plays the role of hole scavenger in this system. Moreover, incomplete EDTA decomposition contributes to the occurrence of intermediates, including nitrilotriacetic acid, iminodiacetic acid, glycine, oxamic acid, lyoxylic acid, oxalic acid, acetic acid and formic acid, as identified by GC/MS. Consequently, transformation pathway was determined from these analyzed byproducts and molecular orbital package analysis.","Enhanced photocatalytic activity of chromium(VI) reduction and EDTA oxidization by photoelectrocatalysis combining cationic exchange membrane processes Abs: A novel technology of photoelectrocatalysis (PEC) combining with cationic exchange membrane (CEM) was proposed for simultaneous reduction of chromium(VI) and oxidization of EDTA. The application of CEM was used to enhance the efficiency for prevention of the re-oxidation of reduced chromium with the electron-hole pairs. In this study, effects of current density, pH, TiO dosage, hydraulic retention time (HRT), light intensity and EDTA/Cr(VI) molar ratio were all investigated. The results showed that the optimum conversion efficiency occurred at 4mA/cm with the presence of CEM. Higher conversion efficiencies were observed at lower pH due to the electrostatic attractions between positive charged TiOH, and negatively charged Cr(VI) and EDTA. The optimum TiO loading of 1g/L was depended mainly on the acidic pH range, especially at higher HRT and irradiation intensity. In addition, higher EDTA/Cr(VI) molar ratio enhanced the reduction efficiency of Cr(VI), indicating EDTA plays the role of hole scavenger in this system. Moreover, incomplete EDTA decomposition contributes to the occurrence of intermediates, including nitrilotriacetic acid, iminodiacetic acid, glycine, oxamic acid, lyoxylic acid, oxalic acid, acetic acid and formic acid, as identified by GC/MS. Consequently, transformation pathway was determined from these analyzed byproducts and molecular orbital package analysis."
1509989,Carette et al. 2013,Hexavalent chromium at low concentration alters Sertoli cell barrier and connexin 43 gap junction but not claudin-11 and N-cadherin in the rat seminiferous tubule culture model,"Exposure to toxic metals, specifically those belonging to the nonessential group leads to human health defects and among them reprotoxic effects. The mechanisms by which these metals produce their negative effects on spermatogenesis have not been fully elucidated. By using the Durand's validated seminiferous tubule culture model, which mimics the in vivo situation, we recently reported that concentrations of hexavalent chromium, reported in the literature to be closed to that found in the blood circulation of men, increase the number of germ cell cytogenetic abnormalities. Since this metal is also known to affect cellular junctions, we investigated, in the present study, its potential influence on the Sertoli cell barrier and on junctional proteins present at this level such as connexin 43, claudin-11 and N-cadherin. Cultured seminiferous tubules in bicameral chambers expressed the three junctional proteins and ZO-1 for at least 12days. Exposure to low concentrations of chromium (10?g/l) increased the trans-epithelial resistance without major changes of claudin-11 and N-cadherin expressions but strongly delocalized the gap junction protein connexin 43 from the membrane to the cytoplasm of Sertoli cells. The possibility that the hexavalent chromium-induced alteration of connexin 43 indirectly mediates the effect of the toxic metal on the blood-testis barrier dynamic is postulated.","Hexavalent chromium at low concentration alters Sertoli cell barrier and connexin 43 gap junction but not claudin-11 and N-cadherin in the rat seminiferous tubule culture model Abs: Exposure to toxic metals, specifically those belonging to the nonessential group leads to human health defects and among them reprotoxic effects. The mechanisms by which these metals produce their negative effects on spermatogenesis have not been fully elucidated. By using the Durand's validated seminiferous tubule culture model, which mimics the in vivo situation, we recently reported that concentrations of hexavalent chromium, reported in the literature to be closed to that found in the blood circulation of men, increase the number of germ cell cytogenetic abnormalities. Since this metal is also known to affect cellular junctions, we investigated, in the present study, its potential influence on the Sertoli cell barrier and on junctional proteins present at this level such as connexin 43, claudin-11 and N-cadherin. Cultured seminiferous tubules in bicameral chambers expressed the three junctional proteins and ZO-1 for at least 12days. Exposure to low concentrations of chromium (10?g/l) increased the trans-epithelial resistance without major changes of claudin-11 and N-cadherin expressions but strongly delocalized the gap junction protein connexin 43 from the membrane to the cytoplasm of Sertoli cells. The possibility that the hexavalent chromium-induced alteration of connexin 43 indirectly mediates the effect of the toxic metal on the blood-testis barrier dynamic is postulated."
1509988,Fransway et al. 2013,North American Contact Dermatitis Group patch test results for 2007-2008,"<strong>BACKGROUND: </strong>The North American Contact Dermatitis Group (NACDG) tests patients with suspected allergic contact dermatitis to a broad series of screening allergens and publishes periodic reports.<br /><br /><strong>OBJECTIVE: </strong>The aims of this study were to report the NACDG patch-testing results from January 1, 2007, to December 31, 2008, and to compare results to pooled test data from the previous 2 and 10 years to analyze trends in allergen sensitivity.<br /><br /><strong>METHODS AND MATERIALS: </strong>Standardized patch testing with 65 allergens was used at 13 centers in North America. ? analysis was used for comparisons.<br /><br /><strong>RESULTS: </strong>A total of 5085 patients were tested; 11.8% (598) had an occupationally related skin condition, and 65.3% (3319) had at least 1 allergic patch test reaction, which is identical to the NACDG data from 2005 to 2006. The top 15 most frequently positive allergens were nickel sulfate (19.5%), Myroxylon pereirae (11.0%), neomycin (10.1%), fragrance mix I (9.4%), quaternium-15 (8.6%), cobalt chloride (8.4%), bacitracin (7.9%), formaldehyde (7.7%), methyldibromoglutaronitrile/phenoxyethanol (5.5%), p-phenylenediamine (5.3%), propolis (4.9%), carba mix (4.5%), potassium dichromate (4.1%), fragrance mix II (3.6%), and methylchloroisothiazolinone/methylisothiazolinone (3.6%). There were significant increases in positivity rates to nickel, methylchloroisothiazolinone/methylisothiazolinone, and benzophenone-3. During the same period of study, there were significant decreases in positivity rates to neomycin, fragrance mix I, formaldehyde, thiuram mix, cinnamic aldehyde, propylene glycol, epoxy resin, diazolidinyl urea, amidoamine, ethylenediamine, benzocaine, p-tert-butylphenol formaldehyde resin, dimethylol dimethyl hydantoin, cocamidopropyl betaine, glutaraldehyde, mercaptobenzothiazole, tosylamide formaldehyde resin, budesonide, disperse blue 106, mercapto mix, and chloroxylenol. Twenty-four percent (1221) had a relevant positive reaction to a non-NACDG supplementary allergen; and 180 of these reactions were occupationally relevant.<br /><br /><strong>CONCLUSIONS: </strong>Periodic analysis, surveillance, and publication of multicenter study data sets document trends in allergen reactivity incidence assessed in the patch test clinic setting and provide information on new allergens of relevance.","North American Contact Dermatitis Group patch test results for 2007-2008 Abs: <strong>BACKGROUND: </strong>The North American Contact Dermatitis Group (NACDG) tests patients with suspected allergic contact dermatitis to a broad series of screening allergens and publishes periodic reports.<br /><br /><strong>OBJECTIVE: </strong>The aims of this study were to report the NACDG patch-testing results from January 1, 2007, to December 31, 2008, and to compare results to pooled test data from the previous 2 and 10 years to analyze trends in allergen sensitivity.<br /><br /><strong>METHODS AND MATERIALS: </strong>Standardized patch testing with 65 allergens was used at 13 centers in North America. ? analysis was used for comparisons.<br /><br /><strong>RESULTS: </strong>A total of 5085 patients were tested; 11.8% (598) had an occupationally related skin condition, and 65.3% (3319) had at least 1 allergic patch test reaction, which is identical to the NACDG data from 2005 to 2006. The top 15 most frequently positive allergens were nickel sulfate (19.5%), Myroxylon pereirae (11.0%), neomycin (10.1%), fragrance mix I (9.4%), quaternium-15 (8.6%), cobalt chloride (8.4%), bacitracin (7.9%), formaldehyde (7.7%), methyldibromoglutaronitrile/phenoxyethanol (5.5%), p-phenylenediamine (5.3%), propolis (4.9%), carba mix (4.5%), potassium dichromate (4.1%), fragrance mix II (3.6%), and methylchloroisothiazolinone/methylisothiazolinone (3.6%). There were significant increases in positivity rates to nickel, methylchloroisothiazolinone/methylisothiazolinone, and benzophenone-3. During the same period of study, there were significant decreases in positivity rates to neomycin, fragrance mix I, formaldehyde, thiuram mix, cinnamic aldehyde, propylene glycol, epoxy resin, diazolidinyl urea, amidoamine, ethylenediamine, benzocaine, p-tert-butylphenol formaldehyde resin, dimethylol dimethyl hydantoin, cocamidopropyl betaine, glutaraldehyde, mercaptobenzothiazole, tosylamide formaldehyde resin, budesonide, disperse blue 106, mercapto mix, and chloroxylenol. Twenty-four percent (1221) had a relevant positive reaction to a non-NACDG supplementary allergen; and 180 of these reactions were occupationally relevant.<br /><br /><strong>CONCLUSIONS: </strong>Periodic analysis, surveillance, and publication of multicenter study data sets document trends in allergen reactivity incidence assessed in the patch test clinic setting and provide information on new allergens of relevance."
1509987,Witt et al. 2013,Mechanistic Insights from the NTP Studies of Chromium,"Hexavalent chromium (Cr(VI)) is a contaminant of water and soil and is a human lung carcinogen. Trivalent chromium (Cr(III)), a proposed essential element, is ingested by humans in the diet and in dietary supplements such as chromium picolinate (CP). The National Toxicology Program (NTP) demonstrated that Cr(VI) is also carcinogenic in rodents when administered in drinking water as sodium dichromate dihydrate (SDD), inducing neoplasms of the oral cavity and small intestine in rats and mice, respectively. In contrast, there was no definitive evidence of toxicity or carcinogenicity following exposure to Cr(III) administered in feed as CP monohydrate (CPM). Cr(VI) readily enters cells via nonspecific anion channels, in contrast to Cr(III), which cannot easily pass through the cell membrane. Extracellular reduction of Cr(VI) to Cr(III), which occurs primarily in the stomach, is considered a mechanism of detoxification, while intracellular reduction is thought to be a mechanism of genotoxicity and carcinogenicity. Tissue distribution studies in additional groups of male rats and female mice demonstrated higher Cr concentrations in tissues following exposure to Cr(VI) compared to controls and Cr(III) exposure at a similar external dose, indicating that some of the Cr(VI) escaped gastric reduction and was distributed systemically. The multiple potential pathways of Cr-induced genotoxicity will be discussed.","Mechanistic Insights from the NTP Studies of Chromium Abs: Hexavalent chromium (Cr(VI)) is a contaminant of water and soil and is a human lung carcinogen. Trivalent chromium (Cr(III)), a proposed essential element, is ingested by humans in the diet and in dietary supplements such as chromium picolinate (CP). The National Toxicology Program (NTP) demonstrated that Cr(VI) is also carcinogenic in rodents when administered in drinking water as sodium dichromate dihydrate (SDD), inducing neoplasms of the oral cavity and small intestine in rats and mice, respectively. In contrast, there was no definitive evidence of toxicity or carcinogenicity following exposure to Cr(III) administered in feed as CP monohydrate (CPM). Cr(VI) readily enters cells via nonspecific anion channels, in contrast to Cr(III), which cannot easily pass through the cell membrane. Extracellular reduction of Cr(VI) to Cr(III), which occurs primarily in the stomach, is considered a mechanism of detoxification, while intracellular reduction is thought to be a mechanism of genotoxicity and carcinogenicity. Tissue distribution studies in additional groups of male rats and female mice demonstrated higher Cr concentrations in tissues following exposure to Cr(VI) compared to controls and Cr(III) exposure at a similar external dose, indicating that some of the Cr(VI) escaped gastric reduction and was distributed systemically. The multiple potential pathways of Cr-induced genotoxicity will be discussed."
1509986,Araújo and  Souza-Santos 2013,"Use of the microalgae Thalassiosira weissflogii to assess water toxicity in the Suape industrial-port complex of Pernambuco, Brazil","Microalgae are among the organisms that are most frequently recommended to assess water toxicity levels. They provide qualitative and quantitative population changes and have become important in environmental monitoring. The aim of the present study was to assess the sensitivity of the microalgae Thalassiosira weissflogii to water toxicity in the Suape industrial-port complex, and to potassium dichromate in the months of July, September and November of 2010 and January and September of 2011, as well as to compare the microalgae results to those obtained in tests with the sea urchin Lytechinus variegatus. The chronic toxicity tests with both species followed standardized methods. Once the exposure period was completed, the population increase of the algae was assessed using cell density and growth rate data and the percentage of L. variegatus pluteus larvae revealing normal and aberrant development was determined. The algal growth and percentage of pluteus results demonstrated that toxicity in the studied area varied according to the month. The present study confirmed that the best timeframe to conclude tests with the microalgae T. weissflogii was 72h. The microalgae cell density results after 72h were sufficient to assess the toxicity of surface water samples and were more sensible than the growth rates. The microalgae T. weissflogii was a sensitive test-organism for seawater toxicity.","Use of the microalgae Thalassiosira weissflogii to assess water toxicity in the Suape industrial-port complex of Pernambuco, Brazil Abs: Microalgae are among the organisms that are most frequently recommended to assess water toxicity levels. They provide qualitative and quantitative population changes and have become important in environmental monitoring. The aim of the present study was to assess the sensitivity of the microalgae Thalassiosira weissflogii to water toxicity in the Suape industrial-port complex, and to potassium dichromate in the months of July, September and November of 2010 and January and September of 2011, as well as to compare the microalgae results to those obtained in tests with the sea urchin Lytechinus variegatus. The chronic toxicity tests with both species followed standardized methods. Once the exposure period was completed, the population increase of the algae was assessed using cell density and growth rate data and the percentage of L. variegatus pluteus larvae revealing normal and aberrant development was determined. The algal growth and percentage of pluteus results demonstrated that toxicity in the studied area varied according to the month. The present study confirmed that the best timeframe to conclude tests with the microalgae T. weissflogii was 72h. The microalgae cell density results after 72h were sufficient to assess the toxicity of surface water samples and were more sensible than the growth rates. The microalgae T. weissflogii was a sensitive test-organism for seawater toxicity."
1509985,Morrone et al. ,Clinical-epidemiological features of contact dermatitis in rural and urban communities in northern Ethiopia: correlation with environmental or occupational exposure,"BACKGROUND: The widespread diffusion of low-quality products as well as the local cultural habits could be a relevant cause of allergic diseases in developing countries. In the present observational study, we explored the prevalence of allergic contact dermatitis in both rural and urban settings in northern Ethiopia, where skin diseases represent a frequent cause of morbidity. Clinical features and specific reactivities in association with environmental or occupational exposure were investigated. PATIENTS AND METHODS: We patch tested 480 consecutive patients, visited at the Mekele IDC, exhibiting symptoms of contact dermatitis. A detailed medical history of each patient was collected. RESULTS: A positive patch-test response was observed in 50% of subjects; nickel was the most frequent sensitizer (26.2%), followed by p-tert-butylphenol formaldehyde resin (10%), fragrance mix (7.1%), potassium dichromate (5.4%), cobalt chloride (4.6%), disperse blue (2.3%), and p-phenylenediamine (1.7%). Gender-related differences were analyzed for single allergen. Eczema represented the most common manifestation, affecting the head and neck as primary skin areas. While reactivity to nickel interested almost all the occupational categories, sensitization to other allergens could be ascribed to working habits or environmental exposure. CONCLUSIONS: The results gathered from this study, the first one conducted within the Tigray region in Ethiopia, confirm the need to take appropriate measures to limit the nickel rate in metal objects and may be useful to design allergenic series suitable for patch testing in those geographical settings.","Clinical-epidemiological features of contact dermatitis in rural and urban communities in northern Ethiopia: correlation with environmental or occupational exposure Abs: BACKGROUND: The widespread diffusion of low-quality products as well as the local cultural habits could be a relevant cause of allergic diseases in developing countries. In the present observational study, we explored the prevalence of allergic contact dermatitis in both rural and urban settings in northern Ethiopia, where skin diseases represent a frequent cause of morbidity. Clinical features and specific reactivities in association with environmental or occupational exposure were investigated. PATIENTS AND METHODS: We patch tested 480 consecutive patients, visited at the Mekele IDC, exhibiting symptoms of contact dermatitis. A detailed medical history of each patient was collected. RESULTS: A positive patch-test response was observed in 50% of subjects; nickel was the most frequent sensitizer (26.2%), followed by p-tert-butylphenol formaldehyde resin (10%), fragrance mix (7.1%), potassium dichromate (5.4%), cobalt chloride (4.6%), disperse blue (2.3%), and p-phenylenediamine (1.7%). Gender-related differences were analyzed for single allergen. Eczema represented the most common manifestation, affecting the head and neck as primary skin areas. While reactivity to nickel interested almost all the occupational categories, sensitization to other allergens could be ascribed to working habits or environmental exposure. CONCLUSIONS: The results gathered from this study, the first one conducted within the Tigray region in Ethiopia, confirm the need to take appropriate measures to limit the nickel rate in metal objects and may be useful to design allergenic series suitable for patch testing in those geographical settings."
1509984,Qiang et al. 2013,Optimization of fermentation conditions and properties of an exopolysaccharide from Klebsiella sp. H-207 and application in adsorption of hexavalent chromium,"The novel exopolysaccharide HZ-7 is produced by Klebsiella sp. H-207, and its fermentation conditions were optimized by response surface methodology (RSM). In this study, the optimized medium consisted of sucrose 31.93 g/L, KNO(3) 2.17 g/L and K(2)HPO(4) 5.47 g/L; while the optimized culture conditions consisted of seed age 13 h, with an inoculum size of 10.6% and incubation temperature of 28.9°C. A maximum HZ-7 yield of about 15.05 g/L was achieved under the optimized conditions using RSM and single-factor experiments. Next the exopolysaccharide HZ-7 was partially purified and characterized. The resulting product showed good properties, such as high concentration of uronic acid (41.67%), low average molecular weight (about 1.94×10(5) Da) and porous surface structure, were very advantageous to biosorption. Therefore HZ-7 was applied to absorb hexavalent chromium (Cr(VI)). The maximum adsorption efficiency (99.2%) which was obtained at an initial pH of 1.0 along with an initial Cr(VI) concentration of 20 mg/L, was not affected by ordinary metal ions and temperature. These data suggest Klebsiella sp. H-207 exopolysaccharide will be promising potential for industrial application.","Optimization of fermentation conditions and properties of an exopolysaccharide from Klebsiella sp. H-207 and application in adsorption of hexavalent chromium Abs: The novel exopolysaccharide HZ-7 is produced by Klebsiella sp. H-207, and its fermentation conditions were optimized by response surface methodology (RSM). In this study, the optimized medium consisted of sucrose 31.93 g/L, KNO(3) 2.17 g/L and K(2)HPO(4) 5.47 g/L; while the optimized culture conditions consisted of seed age 13 h, with an inoculum size of 10.6% and incubation temperature of 28.9°C. A maximum HZ-7 yield of about 15.05 g/L was achieved under the optimized conditions using RSM and single-factor experiments. Next the exopolysaccharide HZ-7 was partially purified and characterized. The resulting product showed good properties, such as high concentration of uronic acid (41.67%), low average molecular weight (about 1.94×10(5) Da) and porous surface structure, were very advantageous to biosorption. Therefore HZ-7 was applied to absorb hexavalent chromium (Cr(VI)). The maximum adsorption efficiency (99.2%) which was obtained at an initial pH of 1.0 along with an initial Cr(VI) concentration of 20 mg/L, was not affected by ordinary metal ions and temperature. These data suggest Klebsiella sp. H-207 exopolysaccharide will be promising potential for industrial application."
1509983,Oyetibo et al. ,Chromium (VI) biosorption properties of multiple resistant bacteria isolated from industrial sewerage,"Chromium (VI) [Cr (VI)] biosorption by four resistant autochthonous bacterial strains was investigated to determine their potential for use in sustainable marine water-pollution control. Maximum exchange between Cr (VI) ions and protons on the cells surfaces were at 30-35 °C, pH?2.0 and 350-450 mg/L. The bacterial strains effectively removed 79.0-90.5 % Cr (VI) ions from solution. Furthermore, 85.3-93.0 % of Cr (VI) ions were regenerated from the biomasses, and 83.4-91.7 % of the metal was adsorbed when the biomasses was reused. Langmuir isotherm performed better than Freundlich isotherm, depicting that Cr (VI) affinity was in the sequence Rhodococcus sp. AL03Ni?&gt;?Burkholderia cepacia AL96Co?&gt;?Corynebacterium kutscheri FL108Hg?&gt;?Pseudomonas aeruginosa CA207Ni. Biosorption isotherms confirmed that Rhodococcus sp. AL03Ni was a better biosorbent with a maximum uptake of 107.46 mg of Cr (VI) per g (dry weight) of biomass. The results highlight the high potential of the organisms for bacteria-based detoxification of Cr (VI) via biosorption.","Chromium (VI) biosorption properties of multiple resistant bacteria isolated from industrial sewerage Abs: Chromium (VI) [Cr (VI)] biosorption by four resistant autochthonous bacterial strains was investigated to determine their potential for use in sustainable marine water-pollution control. Maximum exchange between Cr (VI) ions and protons on the cells surfaces were at 30-35 °C, pH?2.0 and 350-450 mg/L. The bacterial strains effectively removed 79.0-90.5 % Cr (VI) ions from solution. Furthermore, 85.3-93.0 % of Cr (VI) ions were regenerated from the biomasses, and 83.4-91.7 % of the metal was adsorbed when the biomasses was reused. Langmuir isotherm performed better than Freundlich isotherm, depicting that Cr (VI) affinity was in the sequence Rhodococcus sp. AL03Ni?&gt;?Burkholderia cepacia AL96Co?&gt;?Corynebacterium kutscheri FL108Hg?&gt;?Pseudomonas aeruginosa CA207Ni. Biosorption isotherms confirmed that Rhodococcus sp. AL03Ni was a better biosorbent with a maximum uptake of 107.46 mg of Cr (VI) per g (dry weight) of biomass. The results highlight the high potential of the organisms for bacteria-based detoxification of Cr (VI) via biosorption."
1509982,Yuan et al. 2012,Effects of dentifrice containing hydroxyapatite on dentinal tubule occlusion and aqueous hexavalent chromium cations sorption: a preliminary study,"In order to endow environmental protection features to dentifrice, hydroxyapatite (HA) was added to ordinary dentifrice. The effects on dentinal tubule occlusion and surface mineralization were compared after brushing dentine discs with dentifrice with or without HA. The two types of dentifrice were then added to 100 µg/ml of hexavalent chromium cation (Cr(6+)) solution in order to evaluate their capacities of adsorbing Cr(6+) from water. Our results showed that the dentifrice containing HA was significantly better than the ordinary dentifrice in occluding the dentinal tubules with a plugging rate greater than 90%. Moreover, the effect of the HA dentifrice was persistent and energy-dispersive spectrometer (EDS) revealed that the atomic percentages of calcium and phosphorus on the surface of dentine discs increased significantly. Adding HA to ordinary dentifrice significantly enhanced the ability of dentifrice to adsorb Cr(6+) from water with the removal rate up to 52.36%. In addition, the sorption was stable. Our study suggests that HA can be added to ordinary dentifrice to obtain dentifrice that has both relieving dentin hypersensitivity benefits and also helps to control environmental pollution.","Effects of dentifrice containing hydroxyapatite on dentinal tubule occlusion and aqueous hexavalent chromium cations sorption: a preliminary study Abs: In order to endow environmental protection features to dentifrice, hydroxyapatite (HA) was added to ordinary dentifrice. The effects on dentinal tubule occlusion and surface mineralization were compared after brushing dentine discs with dentifrice with or without HA. The two types of dentifrice were then added to 100 µg/ml of hexavalent chromium cation (Cr(6+)) solution in order to evaluate their capacities of adsorbing Cr(6+) from water. Our results showed that the dentifrice containing HA was significantly better than the ordinary dentifrice in occluding the dentinal tubules with a plugging rate greater than 90%. Moreover, the effect of the HA dentifrice was persistent and energy-dispersive spectrometer (EDS) revealed that the atomic percentages of calcium and phosphorus on the surface of dentine discs increased significantly. Adding HA to ordinary dentifrice significantly enhanced the ability of dentifrice to adsorb Cr(6+) from water with the removal rate up to 52.36%. In addition, the sorption was stable. Our study suggests that HA can be added to ordinary dentifrice to obtain dentifrice that has both relieving dentin hypersensitivity benefits and also helps to control environmental pollution."
1509981,Kuk et al. 2012,Stool sample storage conditions for the preservation of Giardia intestinalis DNA,"Stool is chemically complex and the extraction of DNA from stool samples is extremely difficult. Haemoglobin breakdown products, such as bilirubin, bile acids and mineral ions, that are present in the stool samples, can inhibit DNA amplification and cause molecular assays to produce false-negative results. Therefore, stool storage conditions are highly important for the diagnosis of intestinal parasites and other microorganisms through molecular approaches. In the current study, stool samples that were positive for Giardia intestinalis were collected from five different patients. Each sample was stored using one out of six different storage conditions [room temperature (RT), +4ºC, -20ºC, 70% alcohol, 10% formaldehyde or 2.5% potassium dichromate] for DNA extraction procedures at one, two, three and four weeks. A modified QIAamp Stool Mini Kit procedure was used to isolate the DNA from stored samples. After DNA isolation, polymerase chain reaction (PCR) amplification was performed using primers that target the ?-giardin gene. A G. intestinalis-specific 384 bp band was obtained from all of the cyst-containing stool samples that were stored at RT, +4ºC and -20ºC and in 70% alcohol and 2.5% potassium dichromate; however, this band was not produced by samples that had been stored in 10% formaldehyde. Moreover, for the stool samples containing trophozoites, the same G. intestinalis-specific band was only obtained from the samples that were stored in 2.5% potassium dichromate for up to one month. As a result, it appears evident that the most suitable storage condition for stool samples to permit the isolation of G. intestinalis DNA is in 2.5% potassium dichromate; under these conditions, stool samples may be stored for one month.","Stool sample storage conditions for the preservation of Giardia intestinalis DNA Abs: Stool is chemically complex and the extraction of DNA from stool samples is extremely difficult. Haemoglobin breakdown products, such as bilirubin, bile acids and mineral ions, that are present in the stool samples, can inhibit DNA amplification and cause molecular assays to produce false-negative results. Therefore, stool storage conditions are highly important for the diagnosis of intestinal parasites and other microorganisms through molecular approaches. In the current study, stool samples that were positive for Giardia intestinalis were collected from five different patients. Each sample was stored using one out of six different storage conditions [room temperature (RT), +4ºC, -20ºC, 70% alcohol, 10% formaldehyde or 2.5% potassium dichromate] for DNA extraction procedures at one, two, three and four weeks. A modified QIAamp Stool Mini Kit procedure was used to isolate the DNA from stored samples. After DNA isolation, polymerase chain reaction (PCR) amplification was performed using primers that target the ?-giardin gene. A G. intestinalis-specific 384 bp band was obtained from all of the cyst-containing stool samples that were stored at RT, +4ºC and -20ºC and in 70% alcohol and 2.5% potassium dichromate; however, this band was not produced by samples that had been stored in 10% formaldehyde. Moreover, for the stool samples containing trophozoites, the same G. intestinalis-specific band was only obtained from the samples that were stored in 2.5% potassium dichromate for up to one month. As a result, it appears evident that the most suitable storage condition for stool samples to permit the isolation of G. intestinalis DNA is in 2.5% potassium dichromate; under these conditions, stool samples may be stored for one month."
1509980,Nowicka et al. 2013,Chromium(VI) but not chromium(III) species decrease mitoxantrone affinity to DNA,"Binding of mitoxantrone (MXT) to double-stranded DNA has been investigated as a model drug-DNA binding system to evaluate the effects of various forms of chromium on the binding properties. We have found that Cr(III), which binds strongly to DNA, does not affect the MXT affinity to DNA. In contrast, Cr(VI), in the form of chromate ions CrO(4)(2-), decreases the MXT affinity to DNA despite electrostatic repulsions with phosphate-deoxyribose chains of DNA. The MXT-DNA binding constant was found to decrease from (1.96 ± 0.005) × 10(5) to (0.77 ± 0.018) × 10(5) M(-1) for Cr(VI) concentration changing from 0 to 30 ?M. The influence of Cr(VI) on MXT-DNA binding has been attributed to the oxidation of guanine residue, thus interrupting the intercalation of MXT into the DNA double helix at the preferential CpG intercalation site. This supposition is corroborated by the observed increase in the MXT binding site size from 2 bp (base pairs) to 4-6 bp in the presence of Cr(VI). The measurements of the MXT-DNA binding constant and the MXT binding site size on a DNA molecule have been carried out using spectroscopic, voltammetric, and nanogravimetric techniques, providing useful information on the mechanism of the interactions.","Chromium(VI) but not chromium(III) species decrease mitoxantrone affinity to DNA Abs: Binding of mitoxantrone (MXT) to double-stranded DNA has been investigated as a model drug-DNA binding system to evaluate the effects of various forms of chromium on the binding properties. We have found that Cr(III), which binds strongly to DNA, does not affect the MXT affinity to DNA. In contrast, Cr(VI), in the form of chromate ions CrO(4)(2-), decreases the MXT affinity to DNA despite electrostatic repulsions with phosphate-deoxyribose chains of DNA. The MXT-DNA binding constant was found to decrease from (1.96 ± 0.005) × 10(5) to (0.77 ± 0.018) × 10(5) M(-1) for Cr(VI) concentration changing from 0 to 30 ?M. The influence of Cr(VI) on MXT-DNA binding has been attributed to the oxidation of guanine residue, thus interrupting the intercalation of MXT into the DNA double helix at the preferential CpG intercalation site. This supposition is corroborated by the observed increase in the MXT binding site size from 2 bp (base pairs) to 4-6 bp in the presence of Cr(VI). The measurements of the MXT-DNA binding constant and the MXT binding site size on a DNA molecule have been carried out using spectroscopic, voltammetric, and nanogravimetric techniques, providing useful information on the mechanism of the interactions."
1509979,Rembacz et al. 2012,Role of estradiol in chromium-induced oxidative stress,"This study investigated the role of 17beta-estradiol in chromium-generated oxidative stress in order to determine whether it has a detoxifying activity or increases the toxic effects of chromium compounds. Reduced glutathione (GSH) levels, membrane lipid peroxidation (levels of malondialdehyde -- MDA), glutathione peroxidase (GPx), and superoxide dismutase (SOD) activities were measured in blood. Isolated mitochondria were used to investigate the MDA levels and hydroxyl radical (OHradical) generation. The results showed a varying influence of estradiol on the chromium-induced oxidative stress. This paper demonstrated, that 17beta-estradiol showed a positive effect when erythrocytes were exposed to moderate concentrations of CrVI and increased the levels of erythrocytal GSH. Estradiol did not show any interactions with chromium on the antioxidative enzymes (SOD in erythrocytes and GPx in whole blood) activity measurements. Additionally, estradiol played a generally positive role in the chromium-induced lipid peroxidation in erythrocytes. Unexpectedly, the interaction of estradiol with chromium was found in human mitochondria, where estradiol increased the MDA levels induced by both forms of chromium. Estradiol also increased the OHradical generation triggered with CrVI. It appeared that estradiol acted protectively on lipid peroxidation caused by chromium in erythrocytes but gave an interaction with Cr in mitochondria, which partially correlated with hydroxyl radical formation in this organelle.","Role of estradiol in chromium-induced oxidative stress Abs: This study investigated the role of 17beta-estradiol in chromium-generated oxidative stress in order to determine whether it has a detoxifying activity or increases the toxic effects of chromium compounds. Reduced glutathione (GSH) levels, membrane lipid peroxidation (levels of malondialdehyde -- MDA), glutathione peroxidase (GPx), and superoxide dismutase (SOD) activities were measured in blood. Isolated mitochondria were used to investigate the MDA levels and hydroxyl radical (OHradical) generation. The results showed a varying influence of estradiol on the chromium-induced oxidative stress. This paper demonstrated, that 17beta-estradiol showed a positive effect when erythrocytes were exposed to moderate concentrations of CrVI and increased the levels of erythrocytal GSH. Estradiol did not show any interactions with chromium on the antioxidative enzymes (SOD in erythrocytes and GPx in whole blood) activity measurements. Additionally, estradiol played a generally positive role in the chromium-induced lipid peroxidation in erythrocytes. Unexpectedly, the interaction of estradiol with chromium was found in human mitochondria, where estradiol increased the MDA levels induced by both forms of chromium. Estradiol also increased the OHradical generation triggered with CrVI. It appeared that estradiol acted protectively on lipid peroxidation caused by chromium in erythrocytes but gave an interaction with Cr in mitochondria, which partially correlated with hydroxyl radical formation in this organelle."
1509978,Sarahney et al. 2012,Role of Iron Anode Oxidation on Transformation of Chromium by Electrolysis,"The potential for chemical reduction of hexavalent chromium Cr(VI) in contaminated water and formation of a stable precipitate by Zero Valent Iron (ZVI) anode electrolysis is evaluated in separated electrodes system. Oxidation of iron electrodes produces ferrous ions causing the development of a reducing environment in the anolyte, chemical reduction of Cr(VI) to Cr(III) and formation of stable iron-chromium precipitates. Cr(VI) transformation rates are dependent on the applied electric current density. Increasing the electric current increases the transformation rates; however, the process is more efficient under lower volumetric current density (for example 1.5 mA L(-1) in this study). The transformation follows a zero order rate that is dependent on the electric current density. Cr(VI) transformation occurs in the anolyte when the electrodes are separated as well as when the electrolytes (anolyte/catholyte) are mixed, as used in electrocoagulation. The study shows that the transformation occurs in the anolyte as a result of ferrous ion formation and the product is a stable Fe(15)Cr(5)(OH)(60) precipitate.","Role of Iron Anode Oxidation on Transformation of Chromium by Electrolysis Abs: The potential for chemical reduction of hexavalent chromium Cr(VI) in contaminated water and formation of a stable precipitate by Zero Valent Iron (ZVI) anode electrolysis is evaluated in separated electrodes system. Oxidation of iron electrodes produces ferrous ions causing the development of a reducing environment in the anolyte, chemical reduction of Cr(VI) to Cr(III) and formation of stable iron-chromium precipitates. Cr(VI) transformation rates are dependent on the applied electric current density. Increasing the electric current increases the transformation rates; however, the process is more efficient under lower volumetric current density (for example 1.5 mA L(-1) in this study). The transformation follows a zero order rate that is dependent on the electric current density. Cr(VI) transformation occurs in the anolyte when the electrodes are separated as well as when the electrolytes (anolyte/catholyte) are mixed, as used in electrocoagulation. The study shows that the transformation occurs in the anolyte as a result of ferrous ion formation and the product is a stable Fe(15)Cr(5)(OH)(60) precipitate."
1509977,Li et al. 2013,A subnanomole level photoelectrochemical sensing platform for hexavalent chromium based on its selective inhibition of quercetin oxidation,"An indirect photoelectrochemical sensing platform for toxic hexavalent chromium was for the first time constructed based on its redox reaction with quercetin as both the electron donor and photosensitizer on a TiO(2) photoanode, and thus inhibiting the photocurrent quantitatively and selectively. The presence of even 500-fold coexisting Cr(III) does not interfere in the detection of Cr(VI). Under the optimum conditions, the electrode displayed a linear decrease response as the Cr(VI) concentration increased from 1 to 10 nmol L(-1) and from 20 to 140 nmol L(-1) with a detection limit of 0.24 nmol L(-1). Many possible ions in drinking water did not interfere with the detection, and the real sample detection results agreed well with those obtained by GFAAS. This work provide a novel methodology for the simple, low-cost photoelectrochemical detection of Cr(VI) in drinking water.","A subnanomole level photoelectrochemical sensing platform for hexavalent chromium based on its selective inhibition of quercetin oxidation Abs: An indirect photoelectrochemical sensing platform for toxic hexavalent chromium was for the first time constructed based on its redox reaction with quercetin as both the electron donor and photosensitizer on a TiO(2) photoanode, and thus inhibiting the photocurrent quantitatively and selectively. The presence of even 500-fold coexisting Cr(III) does not interfere in the detection of Cr(VI). Under the optimum conditions, the electrode displayed a linear decrease response as the Cr(VI) concentration increased from 1 to 10 nmol L(-1) and from 20 to 140 nmol L(-1) with a detection limit of 0.24 nmol L(-1). Many possible ions in drinking water did not interfere with the detection, and the real sample detection results agreed well with those obtained by GFAAS. This work provide a novel methodology for the simple, low-cost photoelectrochemical detection of Cr(VI) in drinking water."
1509976,Zeng et al. 2013,The protective and toxic effects of rhubarb tannins and anthraquinones in treating hexavalent chromium-injured rats: The Yin/Yang actions of rhubarb,"Chromium nephrotoxicity (CrNT) is thought to occur through the oxidant lesion mechanism. There is still a lack of specific remedies against CrNT. We primarily screened Chinese herbal medicines with a potential protective effect against CrNT, e.g., rhubarb (Rheum palmatum L.). However, the active constituents in rhubarb and its mechanisms remain unclear. In this study, the total rhubarb extract (TR) was successively separated into three parts: total anthraquinone extract (TA), total tannin extract (TT) and remaining component extract (RC). The effects of each extract on the potassium dichromate (K(2)Cr(2)O(7))-induced nephrotoxicity in rats were comparatively assessed. The results showed that only the administration of TT protected the kidney function in K(2)Cr(2)O(7)-injured rats. Besides, TT showed significant activity to scavenge hydroxyl radicals, which is considered to be the dominant lesion product generated by hexavalent chromium. TT also showed a reduced ability to transform toxic high valence chromium ions into non-toxic low valence ions. And TT was able to further precipitate chromium ions. These results suggested that rhubarb tannins treat CrNT as a free radical scavenger, reductant, and metal precipitant. The multiple protective routes of the plant tannins reveal a superior option for development into a promising natural remedy against CrNT. In addition, the opposite effects of rhubarb anthraquinones in treating CrNT were observed compared to rhubarb tannins, which suggested the duo-directional effects (Yin and Yang) of herbal medicines should be addressed.","The protective and toxic effects of rhubarb tannins and anthraquinones in treating hexavalent chromium-injured rats: The Yin/Yang actions of rhubarb Abs: Chromium nephrotoxicity (CrNT) is thought to occur through the oxidant lesion mechanism. There is still a lack of specific remedies against CrNT. We primarily screened Chinese herbal medicines with a potential protective effect against CrNT, e.g., rhubarb (Rheum palmatum L.). However, the active constituents in rhubarb and its mechanisms remain unclear. In this study, the total rhubarb extract (TR) was successively separated into three parts: total anthraquinone extract (TA), total tannin extract (TT) and remaining component extract (RC). The effects of each extract on the potassium dichromate (K(2)Cr(2)O(7))-induced nephrotoxicity in rats were comparatively assessed. The results showed that only the administration of TT protected the kidney function in K(2)Cr(2)O(7)-injured rats. Besides, TT showed significant activity to scavenge hydroxyl radicals, which is considered to be the dominant lesion product generated by hexavalent chromium. TT also showed a reduced ability to transform toxic high valence chromium ions into non-toxic low valence ions. And TT was able to further precipitate chromium ions. These results suggested that rhubarb tannins treat CrNT as a free radical scavenger, reductant, and metal precipitant. The multiple protective routes of the plant tannins reveal a superior option for development into a promising natural remedy against CrNT. In addition, the opposite effects of rhubarb anthraquinones in treating CrNT were observed compared to rhubarb tannins, which suggested the duo-directional effects (Yin and Yang) of herbal medicines should be addressed."
1509975,Ogunbileje et al. 2013,"Lead, mercury, cadmium, chromium, nickel, copper, zinc, calcium, iron, manganese and chromium (VI) levels in Nigeria and United States of America cement dust","This study was aimed at investigating the relative abundance of heavy metals in cement dust from different cement dust factories in order to predict their possible roles in the severity of cement dust toxicity. The concentrations of total mercury (Hg), copper (Cu), chromium (Cr), cadmium (Cd), nickel (Ni), manganese (Mn), lead (Pb), iron (Fe) and chromium (VI) (Cr (VI)) levels in cement dust and clinker samples from Nigeria and cement dust sample from the United States of America (USA) were determined using graphite furnace atomic absorption (GFAAS), while Zn and Ca were measured by flame atomic absorption spectrophotometry (FAAS), and Cr (VI) by colorimetric method. Total Cu, Ni and Mn were significantly higher in cement dust sample from USA (p&lt;0.05), also, both total Cr and Cr (VI) were 5.4-26 folds higher in USA cement dust compared with Nigeria cement dust or clinker (p&lt;0.001). Total Cd was higher in both Nigeria cement dust and clinker (p&lt;0.05 and p&lt;0.001), respectively. Mercury was more in both Nigeria cement dust and clinker (p&lt;0.05), while Pb was only significantly higher in clinker from Nigeria (p&lt;0.001). These results show that cement dust contain mixture of metals that are known human carcinogens and also have been implicated in other debilitating health conditions. Additionally, it revealed that metal content concentrations are factory dependent. This study appears to indicate the need for additional human studies relating the toxicity of these metals and their health impacts on cement factory workers.","Lead, mercury, cadmium, chromium, nickel, copper, zinc, calcium, iron, manganese and chromium (VI) levels in Nigeria and United States of America cement dust Abs: This study was aimed at investigating the relative abundance of heavy metals in cement dust from different cement dust factories in order to predict their possible roles in the severity of cement dust toxicity. The concentrations of total mercury (Hg), copper (Cu), chromium (Cr), cadmium (Cd), nickel (Ni), manganese (Mn), lead (Pb), iron (Fe) and chromium (VI) (Cr (VI)) levels in cement dust and clinker samples from Nigeria and cement dust sample from the United States of America (USA) were determined using graphite furnace atomic absorption (GFAAS), while Zn and Ca were measured by flame atomic absorption spectrophotometry (FAAS), and Cr (VI) by colorimetric method. Total Cu, Ni and Mn were significantly higher in cement dust sample from USA (p&lt;0.05), also, both total Cr and Cr (VI) were 5.4-26 folds higher in USA cement dust compared with Nigeria cement dust or clinker (p&lt;0.001). Total Cd was higher in both Nigeria cement dust and clinker (p&lt;0.05 and p&lt;0.001), respectively. Mercury was more in both Nigeria cement dust and clinker (p&lt;0.05), while Pb was only significantly higher in clinker from Nigeria (p&lt;0.001). These results show that cement dust contain mixture of metals that are known human carcinogens and also have been implicated in other debilitating health conditions. Additionally, it revealed that metal content concentrations are factory dependent. This study appears to indicate the need for additional human studies relating the toxicity of these metals and their health impacts on cement factory workers."
1509974,Lee et al. 2013,Reduction of Chromium(VI) mediated by zero-valent magnesium under neutral pH conditions,"In an effort to assess the potential use of ZVMg in contaminant treatments, we examined Cr(VI) reduction mediated by ZVMg particles under neutral pH conditions. The reduction of Cr(VI) was tested with batch experiments by varying [Cr(VI)](0) (4.9, 9.6, 49.9 or 96.9 ?M) in the presence of 50 mg/L ZVMg particles ([Mg(0)](0) = 2.06 mM) at pH 7 buffered with 50 mM Na-MOPS. When [Cr(VI)](0) = 4.9 or 9.6 ?M, Cr(VI) was completely reduced within 60 min. At higher [Cr(VI)](0) (49.9 or 96.9 ?M), by contrast, the reduction became retarded at &gt;120 min likely due to rapid ZVMg dissolution in water and surface precipitation of Cr(III) on ZVMg particles. Surface precipitation was observed only when [Cr(VI)](0) = 49.9 or 96.9 ?M and increased with increasing [Cr(VI)](0). The effect of dissolved oxygen was negligible on the rate and extent of Cr(VI) reduction. Experimental results indicated that Cr(VI) was reduced not directly by ZVMg but by reactive intermediates produced from ZVMg-water reaction under the experimental conditions employed in this study. In addition, the observed rates of Cr(VI) reduction appeared to follow an order below unity (0.19) with respect to [Cr(VI)](0). These results imply that ZVMg-mediated Cr(VI) reduction likely occurred via an alternative mechanism to the direct surface-mediated reduction typically observed for other zero-valent metals. Rapid and complete Cr(VI) reduction was achieved when a mass ratio of [ZVMg](0):[Cr(VI)](0) ? 100 at neutral pH under both oxic and anoxic conditions. Our results highlights the potential for ZVMg to be used in Cr(VI) treatments especially under neutral pH conditions in the presence of dissolved oxygen.","Reduction of Chromium(VI) mediated by zero-valent magnesium under neutral pH conditions Abs: In an effort to assess the potential use of ZVMg in contaminant treatments, we examined Cr(VI) reduction mediated by ZVMg particles under neutral pH conditions. The reduction of Cr(VI) was tested with batch experiments by varying [Cr(VI)](0) (4.9, 9.6, 49.9 or 96.9 ?M) in the presence of 50 mg/L ZVMg particles ([Mg(0)](0) = 2.06 mM) at pH 7 buffered with 50 mM Na-MOPS. When [Cr(VI)](0) = 4.9 or 9.6 ?M, Cr(VI) was completely reduced within 60 min. At higher [Cr(VI)](0) (49.9 or 96.9 ?M), by contrast, the reduction became retarded at &gt;120 min likely due to rapid ZVMg dissolution in water and surface precipitation of Cr(III) on ZVMg particles. Surface precipitation was observed only when [Cr(VI)](0) = 49.9 or 96.9 ?M and increased with increasing [Cr(VI)](0). The effect of dissolved oxygen was negligible on the rate and extent of Cr(VI) reduction. Experimental results indicated that Cr(VI) was reduced not directly by ZVMg but by reactive intermediates produced from ZVMg-water reaction under the experimental conditions employed in this study. In addition, the observed rates of Cr(VI) reduction appeared to follow an order below unity (0.19) with respect to [Cr(VI)](0). These results imply that ZVMg-mediated Cr(VI) reduction likely occurred via an alternative mechanism to the direct surface-mediated reduction typically observed for other zero-valent metals. Rapid and complete Cr(VI) reduction was achieved when a mass ratio of [ZVMg](0):[Cr(VI)](0) ? 100 at neutral pH under both oxic and anoxic conditions. Our results highlights the potential for ZVMg to be used in Cr(VI) treatments especially under neutral pH conditions in the presence of dissolved oxygen."
1509973,Jeen et al. 2013,Treatment of trichloroethene and hexavalent chromium by granular iron in the presence of dissolved CaCO3,"Column experiments and numerical simulations were conducted to evaluate the effects of Cr(VI) and dissolved CaCO(3) on the iron reactivity towards trichloroethene (TCE) and Cr(VI) reduction. Column experiments included measurements of iron corrosion potential and characterization of surface film composition using Raman spectroscopy. Three columns received different combinations of TCE (5 mg L(-1)), Cr(VI) (10 mg L(-1)) and dissolved CaCO(3) (300 mg L(-1)), after short periods of conditioning with Millipore water followed by 10 mg L(-1) TCE in Millipore water, for a total of 8 months. The results showed that co-existence with TCE did not affect Cr(VI) reduction kinetics, however, the presence of Cr(VI) reduced TCE degradation rates significantly. The formation of Fe(III)/Cr(III) products caused progressive passivation of the iron and was consistent with the increase in corrosion potential. The presence of dissolved CaCO(3) resulted in a stable corrosion potential and faster degradation rates of TCE and Cr(VI). Over time, however, the accumulation of secondary carbonate minerals on the iron surface decreased the iron reactivity. Numerical simulation using a reactive transport model reproduced the observations from the column experiments reasonably well. The simulation can be valuable in the design of PRBs or in the development of effective maintenance procedures for PRBs treating groundwater co-contaminated with Cr(VI) and TCE in the presence of dissolved CaCO(3).","Treatment of trichloroethene and hexavalent chromium by granular iron in the presence of dissolved CaCO3 Abs: Column experiments and numerical simulations were conducted to evaluate the effects of Cr(VI) and dissolved CaCO(3) on the iron reactivity towards trichloroethene (TCE) and Cr(VI) reduction. Column experiments included measurements of iron corrosion potential and characterization of surface film composition using Raman spectroscopy. Three columns received different combinations of TCE (5 mg L(-1)), Cr(VI) (10 mg L(-1)) and dissolved CaCO(3) (300 mg L(-1)), after short periods of conditioning with Millipore water followed by 10 mg L(-1) TCE in Millipore water, for a total of 8 months. The results showed that co-existence with TCE did not affect Cr(VI) reduction kinetics, however, the presence of Cr(VI) reduced TCE degradation rates significantly. The formation of Fe(III)/Cr(III) products caused progressive passivation of the iron and was consistent with the increase in corrosion potential. The presence of dissolved CaCO(3) resulted in a stable corrosion potential and faster degradation rates of TCE and Cr(VI). Over time, however, the accumulation of secondary carbonate minerals on the iron surface decreased the iron reactivity. Numerical simulation using a reactive transport model reproduced the observations from the column experiments reasonably well. The simulation can be valuable in the design of PRBs or in the development of effective maintenance procedures for PRBs treating groundwater co-contaminated with Cr(VI) and TCE in the presence of dissolved CaCO(3)."
1509972,Kuzhiumparambil and  Fu 2013,Effect of oxidizing adulterants on human urinary steroid profiles,"Steroid profiling is the most versatile and informative technique adapted by doping control laboratories for detection of steroid abuse. The absolute concentrations and ratios of endogenous steroids including testosterone, epitestosterone, androsterone, etiocholanolone, 5?-androstane-3?,17?-diol and 5?-androstane-3?,17?-diol constitute the significant characteristics of a steroid profile. In the present study we report the influence of various oxidizing adulterants on the steroid profile of human urine. Gas chromatography-mass spectrometry analysis was carried out to develop the steroid profile of human male and female urine. Oxidants potassium nitrite, sodium hypochlorite, potassium permanganate, cerium ammonium nitrate, sodium metaperiodate, pyridinium chlorochromate, potassium dichromate and potassium perchlorate were reacted with urine at various concentrations and conditions and the effect of these oxidants on the steroid profile were analyzed. Most of the oxidizing chemicals led to significant changes in endogenous steroid profile parameters which were considered stable under normal conditions. These oxidizing chemicals can cause serious problems regarding the interpretation of steroid profiles and have the potential to act as masking agents that can complicate or prevent the detection of the steroid abuse.","Effect of oxidizing adulterants on human urinary steroid profiles Abs: Steroid profiling is the most versatile and informative technique adapted by doping control laboratories for detection of steroid abuse. The absolute concentrations and ratios of endogenous steroids including testosterone, epitestosterone, androsterone, etiocholanolone, 5?-androstane-3?,17?-diol and 5?-androstane-3?,17?-diol constitute the significant characteristics of a steroid profile. In the present study we report the influence of various oxidizing adulterants on the steroid profile of human urine. Gas chromatography-mass spectrometry analysis was carried out to develop the steroid profile of human male and female urine. Oxidants potassium nitrite, sodium hypochlorite, potassium permanganate, cerium ammonium nitrate, sodium metaperiodate, pyridinium chlorochromate, potassium dichromate and potassium perchlorate were reacted with urine at various concentrations and conditions and the effect of these oxidants on the steroid profile were analyzed. Most of the oxidizing chemicals led to significant changes in endogenous steroid profile parameters which were considered stable under normal conditions. These oxidizing chemicals can cause serious problems regarding the interpretation of steroid profiles and have the potential to act as masking agents that can complicate or prevent the detection of the steroid abuse."
1509971,Madureira et al. 2012,Genotoxic agents promote the nuclear accumulation of annexin A2: role of annexin A2 in mitigating DNA damage,"Annexin A2 is an abundant cellular protein that is mainly localized in the cytoplasm and plasma membrane, however a small population has been found in the nucleus, suggesting a nuclear function for the protein. Annexin A2 possesses a nuclear export sequence (NES) and inhibition of the NES is sufficient to cause nuclear accumulation. Here we show that annexin A2 accumulates in the nucleus in response to genotoxic agents including gamma-radiation, UV radiation, etoposide and chromium VI and that this event is mediated by the nuclear export sequence of annexin A2. Nuclear accumulation of annexin A2 is blocked by the antioxidant agent N-acetyl cysteine (NAC) and stimulated by hydrogen peroxide (H?O?), suggesting that this is a reactive oxygen species dependent event. In response to genotoxic agents, cells depleted of annexin A2 show enhanced phospho-histone H2AX and p53 levels, increased numbers of p53-binding protein 1 nuclear foci and increased levels of nuclear 8-oxo-2'-deoxyguanine, suggesting that annexin A2 plays a role in protecting DNA from damage. This is the first report showing the nuclear translocation of annexin A2 in response to genotoxic agents and its role in mitigating DNA damage.","Genotoxic agents promote the nuclear accumulation of annexin A2: role of annexin A2 in mitigating DNA damage Abs: Annexin A2 is an abundant cellular protein that is mainly localized in the cytoplasm and plasma membrane, however a small population has been found in the nucleus, suggesting a nuclear function for the protein. Annexin A2 possesses a nuclear export sequence (NES) and inhibition of the NES is sufficient to cause nuclear accumulation. Here we show that annexin A2 accumulates in the nucleus in response to genotoxic agents including gamma-radiation, UV radiation, etoposide and chromium VI and that this event is mediated by the nuclear export sequence of annexin A2. Nuclear accumulation of annexin A2 is blocked by the antioxidant agent N-acetyl cysteine (NAC) and stimulated by hydrogen peroxide (H?O?), suggesting that this is a reactive oxygen species dependent event. In response to genotoxic agents, cells depleted of annexin A2 show enhanced phospho-histone H2AX and p53 levels, increased numbers of p53-binding protein 1 nuclear foci and increased levels of nuclear 8-oxo-2'-deoxyguanine, suggesting that annexin A2 plays a role in protecting DNA from damage. This is the first report showing the nuclear translocation of annexin A2 in response to genotoxic agents and its role in mitigating DNA damage."
1509970,Kr?cisz et al. 2012,Allergy to orthopedic metal implants - a prospective study,"<strong>OBJECTIVES: </strong>Evaluation of the allergenic properties of the metal knee or hip joint implants 24 months post surgery and assessment of the relation between allergy to metals and metal implants failure.<br /><br /><strong>MATERIALS AND METHODS: </strong>The study was conducted in two stages. Stage I (pre-implantation) - 60 patients scheduled for arthroplasty surgery. Personal interview, dermatological examination and patch testing with 0.5% potassium dichromate, 1.0% cobalt chloride, 5.0% nickel sulfate, 2.0% copper sulfate, 2.0% palladium chloride, 100% aluminum, 1% vanadium chloride, 5% vanadium, 10% titanium oxide, 5% molybdenum and 1% ammonium molybdate tetrahydrate were performed. Stage II (post-surgery) - 48 subjects participated in the same procedures as those conducted in Stage I.<br /><br /><strong>RESULTS: </strong>Stage I - symptoms of &quot;metal dermatitis&quot; were found in 21.7% of the subjects: 27.9% of the females, 5.9% of the males. Positive patch test results were found in 21.7% of the participants, namely to: nickel (20.0%); palladium (13.3%); cobalt (10.0%); and chromium (5.9%). The allergy to metals was confirmed by patch testing in 84.6% of the subjects with a history of metal dermatitis. Stage II - 10.4% of the participants complained about implant intolerance, 4.2% of the examined persons reported skin lesions. Contact allergy to metals was found in 25.0% of the patients: nickel 20.8%, palladium 10.4%, cobalt 16.7%, chromium 8.3%, vanadium 2.1% Positive post-surgery patch tests results were observed in 10.4% of the patients. The statistical analysis of the pre- and post-surgery patch tests results showed that chromium and cobalt can be allergenic in implants.<br /><br /><strong>CONCLUSIONS: </strong>Metal orthopedic implants may be the primary cause of allergies. that may lead to implant failure. Patch tests screening should be obligatory prior to providing implants to patients reporting symptoms of metal dermatitis. People with confirmed allergies to metals should be provided with implants free from allergenic metals.","Allergy to orthopedic metal implants - a prospective study Abs: <strong>OBJECTIVES: </strong>Evaluation of the allergenic properties of the metal knee or hip joint implants 24 months post surgery and assessment of the relation between allergy to metals and metal implants failure.<br /><br /><strong>MATERIALS AND METHODS: </strong>The study was conducted in two stages. Stage I (pre-implantation) - 60 patients scheduled for arthroplasty surgery. Personal interview, dermatological examination and patch testing with 0.5% potassium dichromate, 1.0% cobalt chloride, 5.0% nickel sulfate, 2.0% copper sulfate, 2.0% palladium chloride, 100% aluminum, 1% vanadium chloride, 5% vanadium, 10% titanium oxide, 5% molybdenum and 1% ammonium molybdate tetrahydrate were performed. Stage II (post-surgery) - 48 subjects participated in the same procedures as those conducted in Stage I.<br /><br /><strong>RESULTS: </strong>Stage I - symptoms of &quot;metal dermatitis&quot; were found in 21.7% of the subjects: 27.9% of the females, 5.9% of the males. Positive patch test results were found in 21.7% of the participants, namely to: nickel (20.0%); palladium (13.3%); cobalt (10.0%); and chromium (5.9%). The allergy to metals was confirmed by patch testing in 84.6% of the subjects with a history of metal dermatitis. Stage II - 10.4% of the participants complained about implant intolerance, 4.2% of the examined persons reported skin lesions. Contact allergy to metals was found in 25.0% of the patients: nickel 20.8%, palladium 10.4%, cobalt 16.7%, chromium 8.3%, vanadium 2.1% Positive post-surgery patch tests results were observed in 10.4% of the patients. The statistical analysis of the pre- and post-surgery patch tests results showed that chromium and cobalt can be allergenic in implants.<br /><br /><strong>CONCLUSIONS: </strong>Metal orthopedic implants may be the primary cause of allergies. that may lead to implant failure. Patch tests screening should be obligatory prior to providing implants to patients reporting symptoms of metal dermatitis. People with confirmed allergies to metals should be provided with implants free from allergenic metals."
1509969,da Silva et al. 2013,Determination of mercury in rice by MSFIA and cold vapour atomic fluorescence spectrometry,"In the present paper the use of a MSFIA system for determination of mercury in rice by cold vapour atomic fluorescence spectrometry (CV AFS) is proposed. The sample digestion is performed in a microwave oven using nitric acid and hydrogen peroxide. The experimental conditions for vapour generation were determined using a full two-level factorial design involving the following factors: nitric acid and tin chloride concentrations and sample flow rate. Employing the conditions optimised, the method allows the determination of mercury using the external calibration technique with aqueous standards. The reached limits of detection and quantification were 0.48 and 1.61 ng g?¹ respectively, and the precision (as relative standard deviation) was 3.28% and 1.56% for rice samples with a mercury content of 3.63 and 5.81 ng g?¹, respectively. The method accuracy was confirmed analysing a certified reference material of rice flour furnished by National Institute of Standard and Technology. The interference of nitrous acid and nitrous oxides are removed using potassium dichromate. The method was applied to mercury determination in twelve rice samples acquired in Palma de Mallorca (Spain) between the months of January and April of 2012. The mercury content found varied from 2.15 to 7.25 ng g?¹. These results agree with those reported by others authors.","Determination of mercury in rice by MSFIA and cold vapour atomic fluorescence spectrometry Abs: In the present paper the use of a MSFIA system for determination of mercury in rice by cold vapour atomic fluorescence spectrometry (CV AFS) is proposed. The sample digestion is performed in a microwave oven using nitric acid and hydrogen peroxide. The experimental conditions for vapour generation were determined using a full two-level factorial design involving the following factors: nitric acid and tin chloride concentrations and sample flow rate. Employing the conditions optimised, the method allows the determination of mercury using the external calibration technique with aqueous standards. The reached limits of detection and quantification were 0.48 and 1.61 ng g?¹ respectively, and the precision (as relative standard deviation) was 3.28% and 1.56% for rice samples with a mercury content of 3.63 and 5.81 ng g?¹, respectively. The method accuracy was confirmed analysing a certified reference material of rice flour furnished by National Institute of Standard and Technology. The interference of nitrous acid and nitrous oxides are removed using potassium dichromate. The method was applied to mercury determination in twelve rice samples acquired in Palma de Mallorca (Spain) between the months of January and April of 2012. The mercury content found varied from 2.15 to 7.25 ng g?¹. These results agree with those reported by others authors."
1509968,Shenashen et al. 2013,Ultra-trace recognition and removal of toxic chromium (VI) ions from water using visual mesocaptor,"The key to designing optical mesocaptors is to construct a chromogenic receptor, namely, diphenylcarbazide (DPC), as a nanoscale platform scavenger with different functional characteristics, such as density, accessibility, and intrinsic mobility. Engineering of optical captors allows facile and reliable signaling in continuous monitoring modes, and enables simple and high-speed removal of toxic chromium (VI) ions. Mesoporous aluminosilica monoliths, with unique morphologies, active surface sites, and physical properties, enhance sensing/removal characteristics in terms of sensitivity, selectivity, and response time. The systematic design of optical mesocaptor is based on a densely patterned selective binding site (DPC) in engineered mesocylinder carriers that have multidirectional pores and microsized particle-like monoliths to control the adsorption/detection assays of Cr(VI) ions. Synthetic mesocaptor can be used for visual removal of Cr(VI) ions even at low concentration levels of 10(-10)M (i.e., 0.07 ppb) with rapid response time in minutes. Moreover, these new classes of design-made hybrid mesocaptor exhibit long-term signaling stability and recognition functionalities that provided extraordinary sensitivity, selectivity, reusability, and fast kinetic detection and quantification of various deleterious metal ions in the environment.","Ultra-trace recognition and removal of toxic chromium (VI) ions from water using visual mesocaptor Abs: The key to designing optical mesocaptors is to construct a chromogenic receptor, namely, diphenylcarbazide (DPC), as a nanoscale platform scavenger with different functional characteristics, such as density, accessibility, and intrinsic mobility. Engineering of optical captors allows facile and reliable signaling in continuous monitoring modes, and enables simple and high-speed removal of toxic chromium (VI) ions. Mesoporous aluminosilica monoliths, with unique morphologies, active surface sites, and physical properties, enhance sensing/removal characteristics in terms of sensitivity, selectivity, and response time. The systematic design of optical mesocaptor is based on a densely patterned selective binding site (DPC) in engineered mesocylinder carriers that have multidirectional pores and microsized particle-like monoliths to control the adsorption/detection assays of Cr(VI) ions. Synthetic mesocaptor can be used for visual removal of Cr(VI) ions even at low concentration levels of 10(-10)M (i.e., 0.07 ppb) with rapid response time in minutes. Moreover, these new classes of design-made hybrid mesocaptor exhibit long-term signaling stability and recognition functionalities that provided extraordinary sensitivity, selectivity, reusability, and fast kinetic detection and quantification of various deleterious metal ions in the environment."
1509967,Wojtoniszak and  Mijowska 2012,Controlled oxidation of graphite to graphene oxide with novel oxidants in a bulk scale,"In this study, a novel method of graphite chemical exfoliation to create graphene oxide (GO) is reported. Here, new oxidants were examined: a mixture of perchloric and nitric acids and potassium chromate. Furthermore, an effect of oxidation time, temperature of oxidation, and ultrasonication on graphite exfoliation degree was investigated. The obtained GOs were next reduced with glucose, used as a reducing agent. Detailed analysis of the materials indicated that when graphite was oxidized for 24 h at 50 °C, 5-layered graphene was prepared. An effect of sonication process was also examined, and it was found to enhance the exfoliation to bilayer graphene. Furthermore, when time and temperature were increased to 48 h and 100 °C, respectively, graphite was exfoliated to single-layer graphene. Therefore, it is believed that the proposed route can be applied for the preparation of graphene or few-layered graphene with defined number of layers upon the process parameters optimization and in a bulk scale. The materials were characterized with atomic force microscopy, Fourier-transform infrared spectroscopy, Raman spectroscopy, and X-ray diffraction.","Controlled oxidation of graphite to graphene oxide with novel oxidants in a bulk scale Abs: In this study, a novel method of graphite chemical exfoliation to create graphene oxide (GO) is reported. Here, new oxidants were examined: a mixture of perchloric and nitric acids and potassium chromate. Furthermore, an effect of oxidation time, temperature of oxidation, and ultrasonication on graphite exfoliation degree was investigated. The obtained GOs were next reduced with glucose, used as a reducing agent. Detailed analysis of the materials indicated that when graphite was oxidized for 24 h at 50 °C, 5-layered graphene was prepared. An effect of sonication process was also examined, and it was found to enhance the exfoliation to bilayer graphene. Furthermore, when time and temperature were increased to 48 h and 100 °C, respectively, graphite was exfoliated to single-layer graphene. Therefore, it is believed that the proposed route can be applied for the preparation of graphene or few-layered graphene with defined number of layers upon the process parameters optimization and in a bulk scale. The materials were characterized with atomic force microscopy, Fourier-transform infrared spectroscopy, Raman spectroscopy, and X-ray diffraction."
1509966,Schena et al. 2012,Allergic contact dermatitis in children with and without atopic dermatitis,"<strong>BACKGROUND: </strong>Prevalence and causes of allergic contact dermatitis (ACD) in children vary with time and geographical area.<br /><br /><strong>OBJECTIVE: </strong>This study aimed to determine the relevant allergens causing ACD in children and the relation between ACD and atopic dermatitis (AD).<br /><br /><strong>METHODS: </strong>A cohort study on 349 children (0-15 years old) patch tested over a 7-year period was conducted.<br /><br /><strong>RESULTS: </strong>Patch test results were positive for at least 1 allergen in 69.3% of patients and were relevant in 69.8%. The highest sensitization rate (76.7%) was observed in children who are 0 to 5 years old (n = 86, 64% females), followed by the group of 6- to 10-year olds (70%, n = 157, 47.8% females), whereas 62.3% of 11- to 15-year-old children (n = 106, 59.4%) were sensitized. The most frequent allergens were nickel (16.3%), cobalt (6.9%), Kathon CG (5.4%), potassium dichromate (5.1%), fragrance mix (4.3%), and neomycin (4.3%). Body areas mostly affected were upper limbs and hands (31%). Approximately one third of children also had AD. Allergic contact dermatitis was more widespread in children with AD. Patch tests resulted positive in 55.3% (50% relevant) of AD compared with 76.9% (77.5% relevant) of the children without AD. Sensitizers were similar to children without AD.<br /><br /><strong>CONCLUSIONS: </strong>Very young children showed a high rate of relevant positive patch test reactions to common haptens. Allergic contact dermatitis may easily coexist with AD.","Allergic contact dermatitis in children with and without atopic dermatitis Abs: <strong>BACKGROUND: </strong>Prevalence and causes of allergic contact dermatitis (ACD) in children vary with time and geographical area.<br /><br /><strong>OBJECTIVE: </strong>This study aimed to determine the relevant allergens causing ACD in children and the relation between ACD and atopic dermatitis (AD).<br /><br /><strong>METHODS: </strong>A cohort study on 349 children (0-15 years old) patch tested over a 7-year period was conducted.<br /><br /><strong>RESULTS: </strong>Patch test results were positive for at least 1 allergen in 69.3% of patients and were relevant in 69.8%. The highest sensitization rate (76.7%) was observed in children who are 0 to 5 years old (n = 86, 64% females), followed by the group of 6- to 10-year olds (70%, n = 157, 47.8% females), whereas 62.3% of 11- to 15-year-old children (n = 106, 59.4%) were sensitized. The most frequent allergens were nickel (16.3%), cobalt (6.9%), Kathon CG (5.4%), potassium dichromate (5.1%), fragrance mix (4.3%), and neomycin (4.3%). Body areas mostly affected were upper limbs and hands (31%). Approximately one third of children also had AD. Allergic contact dermatitis was more widespread in children with AD. Patch tests resulted positive in 55.3% (50% relevant) of AD compared with 76.9% (77.5% relevant) of the children without AD. Sensitizers were similar to children without AD.<br /><br /><strong>CONCLUSIONS: </strong>Very young children showed a high rate of relevant positive patch test reactions to common haptens. Allergic contact dermatitis may easily coexist with AD."
1509965,Pacheco et al. 2013,EPR detection of paramagnetic chromium in liver of fish (Anguilla anguilla) treated with dichromate(VI) and associated oxidative stress responses-contribution to elucidation of toxicity mechanisms,"The impact of chromium (Cr) on fish health has been the subject of numerous investigations, establishing a wide spectrum of toxicity, attributed particularly to the hexavalent form [Cr(VI)]. However, reports on the simultaneous assessment of Cr toxicity in fish and its toxico-kinetics, namely involving metal speciation, are scarce. Therefore, keeping in view the understanding of the mechanisms of Cr(VI) toxicity, this work intended to detect the formation of paramagnetic Cr species in liver of Anguilla anguilla following short-term dichromate(VI) intraperitoneal treatment (up to 180 min), assessing simultaneously the pro-oxidant properties. The formation of Cr(V) and Cr(III) was examined by electron paramagnetic resonance (EPR), as an innovative approach in the context of fish toxicology, and related with the levels of total Cr. Cr(V) was successfully detected and quantified by EPR spectrometry, showing a transient occurrence, mostly between 15 and 90 min post-injection, with a peak at 30 min. The limitations of EPR methodology towards the detection and quantification of Cr(III) were confirmed. Although Cr(VI) exposure induced the antioxidant system in the eel's liver, the oxidative deterioration of lipids was not prevented. Overall, the results suggested that Cr(V), as a short-lived species, did not appear to be directly and primarily responsible for the cellular damaging effects observed, since stress responses persisted up to the end of exposure regardless Cr(V) drastic decay. Though further research is needed, ROS mediated pathways (suggested by superoxide dismutase and catalase activity induction) and formation of Cr(III) complexes emerged as the most plausible mechanisms involved in Cr(VI) toxicity.","EPR detection of paramagnetic chromium in liver of fish (Anguilla anguilla) treated with dichromate(VI) and associated oxidative stress responses-contribution to elucidation of toxicity mechanisms Abs: The impact of chromium (Cr) on fish health has been the subject of numerous investigations, establishing a wide spectrum of toxicity, attributed particularly to the hexavalent form [Cr(VI)]. However, reports on the simultaneous assessment of Cr toxicity in fish and its toxico-kinetics, namely involving metal speciation, are scarce. Therefore, keeping in view the understanding of the mechanisms of Cr(VI) toxicity, this work intended to detect the formation of paramagnetic Cr species in liver of Anguilla anguilla following short-term dichromate(VI) intraperitoneal treatment (up to 180 min), assessing simultaneously the pro-oxidant properties. The formation of Cr(V) and Cr(III) was examined by electron paramagnetic resonance (EPR), as an innovative approach in the context of fish toxicology, and related with the levels of total Cr. Cr(V) was successfully detected and quantified by EPR spectrometry, showing a transient occurrence, mostly between 15 and 90 min post-injection, with a peak at 30 min. The limitations of EPR methodology towards the detection and quantification of Cr(III) were confirmed. Although Cr(VI) exposure induced the antioxidant system in the eel's liver, the oxidative deterioration of lipids was not prevented. Overall, the results suggested that Cr(V), as a short-lived species, did not appear to be directly and primarily responsible for the cellular damaging effects observed, since stress responses persisted up to the end of exposure regardless Cr(V) drastic decay. Though further research is needed, ROS mediated pathways (suggested by superoxide dismutase and catalase activity induction) and formation of Cr(III) complexes emerged as the most plausible mechanisms involved in Cr(VI) toxicity."
1509964,Stern et al. 2013,"Two decades of exposure assessment studies on chromate production waste in Jersey City, New Jersey--what we have learned about exposure characterization and its value to public health and remediation","During much of the twentieth century, Jersey City, New Jersey was the leading center of chromate production in the United States. Chromate production produced huge volumes of chromium ore-processing residue containing many parts per million of hexavalent chromium. Starting in the 1990s, we undertook a series of studies to identify exposed populations, sources and pathways of exposure and the effectiveness of remediation activities in Jersey City. These studies revealed the effectiveness and success of the remediation activities. The sequence of studies presented here, builds on the lessons learned from each preceding study and illustrates how these studies advanced the field of exposure science in important ways, including the use of household dust as a measure of exposure to contaminants originating in the outdoor environment; development of effective and reproducible dust sampling; use of household dust to track temporal changes in exposure; understanding of the spatial relationship between sources of passive outdoor particulate emissions and residential exposure; use of focused biomonitoring to assess exposure under conditions of large inter-individual variability; and utility of linking environmental monitoring and biomonitoring. For chromium, the studies have demonstrated the use of Cr(+6)-specific analytical methods for measuring low concentrations of Cr(+6) in household dust and understanding of the occurrence of Cr(+6) in the background residential environment. We strongly recommend that environmental and public health agencies evaluate sites for their potential for off-site exposure and apply these tools in cases with significant potential as appropriate. This approach is especially important when contamination is widespread and/or a large population is potentially exposed. In such cases, these tools should be used to identify, characterize and then reduce the exposure to the off-site as well as on-site population. Importantly, these tools can be used in a demonstrable and quantifiable manner to provide both clarity and closure to concerned stakeholders.","Two decades of exposure assessment studies on chromate production waste in Jersey City, New Jersey--what we have learned about exposure characterization and its value to public health and remediation Abs: During much of the twentieth century, Jersey City, New Jersey was the leading center of chromate production in the United States. Chromate production produced huge volumes of chromium ore-processing residue containing many parts per million of hexavalent chromium. Starting in the 1990s, we undertook a series of studies to identify exposed populations, sources and pathways of exposure and the effectiveness of remediation activities in Jersey City. These studies revealed the effectiveness and success of the remediation activities. The sequence of studies presented here, builds on the lessons learned from each preceding study and illustrates how these studies advanced the field of exposure science in important ways, including the use of household dust as a measure of exposure to contaminants originating in the outdoor environment; development of effective and reproducible dust sampling; use of household dust to track temporal changes in exposure; understanding of the spatial relationship between sources of passive outdoor particulate emissions and residential exposure; use of focused biomonitoring to assess exposure under conditions of large inter-individual variability; and utility of linking environmental monitoring and biomonitoring. For chromium, the studies have demonstrated the use of Cr(+6)-specific analytical methods for measuring low concentrations of Cr(+6) in household dust and understanding of the occurrence of Cr(+6) in the background residential environment. We strongly recommend that environmental and public health agencies evaluate sites for their potential for off-site exposure and apply these tools in cases with significant potential as appropriate. This approach is especially important when contamination is widespread and/or a large population is potentially exposed. In such cases, these tools should be used to identify, characterize and then reduce the exposure to the off-site as well as on-site population. Importantly, these tools can be used in a demonstrable and quantifiable manner to provide both clarity and closure to concerned stakeholders."
1509963,Mukherjee et al. 2013,Efficient combination of promoter and catalyst for chromic acid oxidation of propan-2-ol to acetone in aqueous acid media at room temperature,"Oxidation of propan-2-ol to acetone was carried out in aqueous media at room temperature. The effect of promoter (PA, bpy, phen), micellar catalyst (SDS, CPC, TX-100) and their combination has been studied. The reactions were performed under the condition [Propan-2-ol]T?[Cr(VI)]T at 30°C. Then kobs and half life of all the reaction were determined to identify which promoter and which combination are the most effective for this oxidation. Among the promoters phen accelerates the reaction most in aqueous media. In absence of promoters anionic surfactant SDS increases the rate more effectively than neutral surfactant TX-100. CPC retards the rate in comparison to aqueous media. The rate of the oxidation is highest in presence of the combination of bpy and SDS.","Efficient combination of promoter and catalyst for chromic acid oxidation of propan-2-ol to acetone in aqueous acid media at room temperature Abs: Oxidation of propan-2-ol to acetone was carried out in aqueous media at room temperature. The effect of promoter (PA, bpy, phen), micellar catalyst (SDS, CPC, TX-100) and their combination has been studied. The reactions were performed under the condition [Propan-2-ol]T?[Cr(VI)]T at 30°C. Then kobs and half life of all the reaction were determined to identify which promoter and which combination are the most effective for this oxidation. Among the promoters phen accelerates the reaction most in aqueous media. In absence of promoters anionic surfactant SDS increases the rate more effectively than neutral surfactant TX-100. CPC retards the rate in comparison to aqueous media. The rate of the oxidation is highest in presence of the combination of bpy and SDS."
1509962,Barrera-Oviedo et al. 2013,Protective effect of SnCl2 on K2Cr2O7-induced toxicity in LLC-PK1 cells,"The exposure to hexavalent chromium is often known to cause acute renal failure. It has been found that nonenzymatic antioxidants and the induction of heme oxygenase 1 have protective effects against nephrotoxicity induced by potassium dichromate in vivo. In this work, the effect of stannous chloride, an inducer of heme oxygenase 1, on potassium dichromate-induced toxicity in proximal tubular epithelial cells was studied. Hexavalent chromium levels, peroxynitrite content, reduced thiol content, heme oxygenase activity, reactive oxygen species production, and stannous chloride scavenging capacity were measured. It was found that stannous chloride protects proximal tubular epithelial cells from potassium dichromate-induced cell death. The decrease in extracellular and intracellular hexavalent chromium concentration, the induction of heme oxygenase 1, and the ability to scavenge reactive oxygen species and peroxynitrite are involved in the mechanism by which stannous chloride protects proximal tubular epithelial cells from potassium dichromate-induced toxicity.","Protective effect of SnCl2 on K2Cr2O7-induced toxicity in LLC-PK1 cells Abs: The exposure to hexavalent chromium is often known to cause acute renal failure. It has been found that nonenzymatic antioxidants and the induction of heme oxygenase 1 have protective effects against nephrotoxicity induced by potassium dichromate in vivo. In this work, the effect of stannous chloride, an inducer of heme oxygenase 1, on potassium dichromate-induced toxicity in proximal tubular epithelial cells was studied. Hexavalent chromium levels, peroxynitrite content, reduced thiol content, heme oxygenase activity, reactive oxygen species production, and stannous chloride scavenging capacity were measured. It was found that stannous chloride protects proximal tubular epithelial cells from potassium dichromate-induced cell death. The decrease in extracellular and intracellular hexavalent chromium concentration, the induction of heme oxygenase 1, and the ability to scavenge reactive oxygen species and peroxynitrite are involved in the mechanism by which stannous chloride protects proximal tubular epithelial cells from potassium dichromate-induced toxicity."
1509961,Wang et al. 2012,Double shroud delivery of silica precursor for reducing hexavalent chromium in welding fume,"The welding process yields a high concentration of nanoparticles loaded with hexavalent chromium (Cr(6+)), a known human carcinogen. Previous studies have demonstrated that using tetramethylsilane (TMS) as a shielding gas additive can significantly reduce the Cr(6+) concentration in welding fume particles. In this study, a novel insulated double shroud torch (IDST) was developed to further improve the reduction of airborne Cr(6+) concentration by separating the flows of the primary shielding gas and the TMS carrier gas. Welding fumes were collected from a welding chamber in the laboratory and from a fixed location near the welding arc in a welding facility. The Cr(6+) content was analyzed with ion chromatography and X-ray photoelectron spectroscopy (XPS). Results from the chamber sampling demonstrated that the addition of 3.2 ? 5.1% of TMS carrier gas to the primary shielding gas resulted in more than a 90% reduction of airborne Cr(6+) under all shielding gas flow rates. The XPS result confirmed complete elimination of Cr(6+) inside the amorphous silica shell. Adding 100 ? 1000 ppm of nitric oxide or carbon monoxide to the shielding gas could also reduce Cr(6+) concentrations up to 57% and 35%, respectively; however, these reducing agents created potential hazards from the release of unreacted agents. Results of the field test showed that the addition of 1.6% of TMS carrier gas to the primary shielding gas reduced Cr(6+) concentration to the limitation of detection (1.1 ?g/m(3)). In a worst-case scenario, if TMS vapor leaked into the environment without decomposition and ventilation, the estimated TMS concentration in the condition of field sampling would be a maximum 5.7 ppm, still well below its flammability limit (1%). Based on a previously developed cost model, the use of TMS increases the general cost by 3.8%. No visual deterioration of weld quality caused by TMS was found, although further mechanical testing is necessary.","Double shroud delivery of silica precursor for reducing hexavalent chromium in welding fume Abs: The welding process yields a high concentration of nanoparticles loaded with hexavalent chromium (Cr(6+)), a known human carcinogen. Previous studies have demonstrated that using tetramethylsilane (TMS) as a shielding gas additive can significantly reduce the Cr(6+) concentration in welding fume particles. In this study, a novel insulated double shroud torch (IDST) was developed to further improve the reduction of airborne Cr(6+) concentration by separating the flows of the primary shielding gas and the TMS carrier gas. Welding fumes were collected from a welding chamber in the laboratory and from a fixed location near the welding arc in a welding facility. The Cr(6+) content was analyzed with ion chromatography and X-ray photoelectron spectroscopy (XPS). Results from the chamber sampling demonstrated that the addition of 3.2 ? 5.1% of TMS carrier gas to the primary shielding gas resulted in more than a 90% reduction of airborne Cr(6+) under all shielding gas flow rates. The XPS result confirmed complete elimination of Cr(6+) inside the amorphous silica shell. Adding 100 ? 1000 ppm of nitric oxide or carbon monoxide to the shielding gas could also reduce Cr(6+) concentrations up to 57% and 35%, respectively; however, these reducing agents created potential hazards from the release of unreacted agents. Results of the field test showed that the addition of 1.6% of TMS carrier gas to the primary shielding gas reduced Cr(6+) concentration to the limitation of detection (1.1 ?g/m(3)). In a worst-case scenario, if TMS vapor leaked into the environment without decomposition and ventilation, the estimated TMS concentration in the condition of field sampling would be a maximum 5.7 ppm, still well below its flammability limit (1%). Based on a previously developed cost model, the use of TMS increases the general cost by 3.8%. No visual deterioration of weld quality caused by TMS was found, although further mechanical testing is necessary."
1509960,Sharma et al. 2012,"Groundwater contaminated with hexavalent chromium [Cr (VI)]: a health survey and clinical examination of community inhabitants (Kanpur, India)","<strong>BACKGROUND: </strong>We assessed the health effects of hexavalent chromium groundwater contamination (from tanneries and chrome sulfate manufacturing) in Kanpur, India.<br /><br /><strong>METHODS: </strong>The health status of residents living in areas with high Cr (VI) groundwater contamination (N = 186) were compared to residents with similar social and demographic features living in communities having no elevated Cr (VI) levels (N = 230). Subjects were recruited at health camps in both the areas. Health status was evaluated with health questionnaires, spirometry and blood hematology measures. Cr (VI) was measured in groundwater samples by diphenylcarbazide reagent method.<br /><br /><strong>RESULTS: </strong>Residents from communities with known Cr (VI) contamination had more self-reports of digestive and dermatological disorders and hematological abnormalities. GI distress was reported in 39.2% vs. 17.2% males (AOR = 3.1) and 39.3% vs. 21% females (AOR = 2.44); skin abnormalities in 24.5% vs. 9.2% males (AOR = 3.48) and 25% vs. 4.9% females (AOR = 6.57). Residents from affected communities had greater RBCs (among 30.7% males and 46.1% females), lower MCVs (among 62.8% males) and less platelets (among 68% males and 72% females) than matched controls. There were no differences in leucocytes count and spirometry parameters.<br /><br /><strong>CONCLUSIONS: </strong>Living in communities with Cr (VI) groundwater is associated with gastrointestinal and dermatological complaints and abnormal hematological function. Limitations of this study include small sample size and the lack of long term follow-up.","Groundwater contaminated with hexavalent chromium [Cr (VI)]: a health survey and clinical examination of community inhabitants (Kanpur, India) Abs: <strong>BACKGROUND: </strong>We assessed the health effects of hexavalent chromium groundwater contamination (from tanneries and chrome sulfate manufacturing) in Kanpur, India.<br /><br /><strong>METHODS: </strong>The health status of residents living in areas with high Cr (VI) groundwater contamination (N = 186) were compared to residents with similar social and demographic features living in communities having no elevated Cr (VI) levels (N = 230). Subjects were recruited at health camps in both the areas. Health status was evaluated with health questionnaires, spirometry and blood hematology measures. Cr (VI) was measured in groundwater samples by diphenylcarbazide reagent method.<br /><br /><strong>RESULTS: </strong>Residents from communities with known Cr (VI) contamination had more self-reports of digestive and dermatological disorders and hematological abnormalities. GI distress was reported in 39.2% vs. 17.2% males (AOR = 3.1) and 39.3% vs. 21% females (AOR = 2.44); skin abnormalities in 24.5% vs. 9.2% males (AOR = 3.48) and 25% vs. 4.9% females (AOR = 6.57). Residents from affected communities had greater RBCs (among 30.7% males and 46.1% females), lower MCVs (among 62.8% males) and less platelets (among 68% males and 72% females) than matched controls. There were no differences in leucocytes count and spirometry parameters.<br /><br /><strong>CONCLUSIONS: </strong>Living in communities with Cr (VI) groundwater is associated with gastrointestinal and dermatological complaints and abnormal hematological function. Limitations of this study include small sample size and the lack of long term follow-up."
1509959,Koh et al. 2013,Dust exposure and the risk of cancer in cement industry workers in Korea,"<strong>BACKGROUND: </strong>Cement is used widely in the construction industry, though it contains hazardous chemicals such as hexavalent chromium. Several epidemiological studies have examined the association between cement dust exposure and cancer, but these associations have proved inconclusive. In the present study, we examined the association between dust exposure and cancer in cement industry workers in Korea.<br /><br /><strong>METHODS: </strong>Our cohort consisted of 1,324 men who worked at two Portland cement manufacturing factories between 1997 and 2005. We calculated cumulative dust exposures, then categorized workers into high and low dust exposure groups. Cancer cases were identified between 1997 and 2005 by linking with the national cancer registry. Standardized incidence ratios (SIRs) were calculated for all workers and the high and low dust exposure groups, respectively.<br /><br /><strong>RESULTS: </strong>The SIR for overall cancers in all workers was increased (1.35, 95% CI: 1.01-1.78). The SIR for stomach cancer in the high dust exposure group was increased (2.18, 95% CI: 1.19-3.65), but there was no increased stomach cancer risk in the low dust exposure group. The SIR for rectal cancer in all workers was increased (3.05, 95% CI: 1.32-6.02). Rectal cancer risk was similar in the high and low exposure groups.<br /><br /><strong>CONCLUSIONS: </strong>Our findings suggest a potential association between exposure in the cement industry and an increased risk of stomach and rectal cancers. However, due to the small number of cases, this association should be further investigated in a study with a longer follow-up period and adjustment for confounders. Am. J. Ind. Med. 56:276-281, 2013. © 2012 Wiley Periodicals, Inc.","Dust exposure and the risk of cancer in cement industry workers in Korea Abs: <strong>BACKGROUND: </strong>Cement is used widely in the construction industry, though it contains hazardous chemicals such as hexavalent chromium. Several epidemiological studies have examined the association between cement dust exposure and cancer, but these associations have proved inconclusive. In the present study, we examined the association between dust exposure and cancer in cement industry workers in Korea.<br /><br /><strong>METHODS: </strong>Our cohort consisted of 1,324 men who worked at two Portland cement manufacturing factories between 1997 and 2005. We calculated cumulative dust exposures, then categorized workers into high and low dust exposure groups. Cancer cases were identified between 1997 and 2005 by linking with the national cancer registry. Standardized incidence ratios (SIRs) were calculated for all workers and the high and low dust exposure groups, respectively.<br /><br /><strong>RESULTS: </strong>The SIR for overall cancers in all workers was increased (1.35, 95% CI: 1.01-1.78). The SIR for stomach cancer in the high dust exposure group was increased (2.18, 95% CI: 1.19-3.65), but there was no increased stomach cancer risk in the low dust exposure group. The SIR for rectal cancer in all workers was increased (3.05, 95% CI: 1.32-6.02). Rectal cancer risk was similar in the high and low exposure groups.<br /><br /><strong>CONCLUSIONS: </strong>Our findings suggest a potential association between exposure in the cement industry and an increased risk of stomach and rectal cancers. However, due to the small number of cases, this association should be further investigated in a study with a longer follow-up period and adjustment for confounders. Am. J. Ind. Med. 56:276-281, 2013. © 2012 Wiley Periodicals, Inc."
1509958,Haney et al. 2012,Development of a cancer-based chronic inhalation reference value for hexavalent chromium based on a nonlinear-threshold carcinogenic assessment,"The carcinogenicity of hexavalent chromium(CrVI) is of significant interest to regulatory agencies for the protection of public health and to industry. Additionally, the mode of action (MOA) and conditions under which CrVI may induce carcinogenicity (e.g., reductive capacity considerations) have recently been the subject of significant scientific debate. Epidemiological data supported by data relevant to the carcinogenic MOA support considering nonlinear-threshold carcinogenic assessments for comparison to default linear low-dose extrapolation approaches. This study reviews epidemiological studies available in the scientific literature and conducts additional statistical dose-response analyses to identify potential carcinogenic thresholds and points of departure (PODs) in the context of supportive MOA information for a nonlinear-threshold inhalation carcinogenic assessment. Dosimetric adjustments and application of appropriate uncertainty factors (total UF of 30) to the selected cumulative exposure POD results in a cancer-based chronic inhalation reference value (ReV) of 0.24 ?gCrVI/m(3). This chronic ReV is 300 times higher than the 1 in 100,000 excess cancer risk air concentration of 8E-04 ?g/m(3) based on USEPA's unit risk factor.","Development of a cancer-based chronic inhalation reference value for hexavalent chromium based on a nonlinear-threshold carcinogenic assessment Abs: The carcinogenicity of hexavalent chromium(CrVI) is of significant interest to regulatory agencies for the protection of public health and to industry. Additionally, the mode of action (MOA) and conditions under which CrVI may induce carcinogenicity (e.g., reductive capacity considerations) have recently been the subject of significant scientific debate. Epidemiological data supported by data relevant to the carcinogenic MOA support considering nonlinear-threshold carcinogenic assessments for comparison to default linear low-dose extrapolation approaches. This study reviews epidemiological studies available in the scientific literature and conducts additional statistical dose-response analyses to identify potential carcinogenic thresholds and points of departure (PODs) in the context of supportive MOA information for a nonlinear-threshold inhalation carcinogenic assessment. Dosimetric adjustments and application of appropriate uncertainty factors (total UF of 30) to the selected cumulative exposure POD results in a cancer-based chronic inhalation reference value (ReV) of 0.24 ?gCrVI/m(3). This chronic ReV is 300 times higher than the 1 in 100,000 excess cancer risk air concentration of 8E-04 ?g/m(3) based on USEPA's unit risk factor."
1509957,Xiao et al. 2012,Reduction kinetics of hexavalent chromium in soils and its correlation with soil properties,"The toxicity of chromium (Cr) to biota is related to its chemical forms and consequently to the redox conditions of soils. Hexavalent Cr[Cr(VI)] may undergo natural attenuation through reduction processes. In this study, the reduction kinetics of Cr(VI) in seven soils and its relationships with soil properties were investigated with laboratory incubation experiments. The results indicate that the reduction of Cr(VI) can be described by a first-order reaction. The reduction rates of Cr(VI) in the seven soils decreased in the order: Udic Ferrisols &gt; Stagnic Anthrosols &gt; Calcaric Regosols &gt; Mollisol &gt; Typic Haplustalf &gt; Periudic Argosols &gt; Ustic Cambosols. Simple correlation analysis revealed that the reduction of Cr(VI) in soils was positively related to organic matter content, dissolved organic matter content, Fe(II) content, clay fraction, and to the diversity index of the bacterial community but negatively correlated with easily reducible Mn content. Using stepwise regression, the reduction of Cr(VI) in soil could be quantitatively predicted by the measurement of dissolved organic matter content, Fe(II) content, pH, and soil particle size distribution, with a fitting level of 95.5%. The results indicated that the reduction of Cr(VI) in natural soils is not controlled by a single soil property but is the result of the combined effects of dissolved organic matter, Fe(II), pH, and soil particle size distribution.","Reduction kinetics of hexavalent chromium in soils and its correlation with soil properties Abs: The toxicity of chromium (Cr) to biota is related to its chemical forms and consequently to the redox conditions of soils. Hexavalent Cr[Cr(VI)] may undergo natural attenuation through reduction processes. In this study, the reduction kinetics of Cr(VI) in seven soils and its relationships with soil properties were investigated with laboratory incubation experiments. The results indicate that the reduction of Cr(VI) can be described by a first-order reaction. The reduction rates of Cr(VI) in the seven soils decreased in the order: Udic Ferrisols &gt; Stagnic Anthrosols &gt; Calcaric Regosols &gt; Mollisol &gt; Typic Haplustalf &gt; Periudic Argosols &gt; Ustic Cambosols. Simple correlation analysis revealed that the reduction of Cr(VI) in soils was positively related to organic matter content, dissolved organic matter content, Fe(II) content, clay fraction, and to the diversity index of the bacterial community but negatively correlated with easily reducible Mn content. Using stepwise regression, the reduction of Cr(VI) in soil could be quantitatively predicted by the measurement of dissolved organic matter content, Fe(II) content, pH, and soil particle size distribution, with a fitting level of 95.5%. The results indicated that the reduction of Cr(VI) in natural soils is not controlled by a single soil property but is the result of the combined effects of dissolved organic matter, Fe(II), pH, and soil particle size distribution."
1509956,Adam et al. ,Terrestrial and aquatic ecotoxicity assessment of Cr(VI) by the ReCiPe method calculation (LCIA): application on an old industrial contaminated site,"The most stable forms of chromium in the environment are chromium (III) and chromium (VI), the former being relatively immobile and necessary for organisms, and the latter being highly soluble and toxic. It is thus important to characterise ecotoxicological impacts of Cr(VI). However, there are still some important uncertainties in the calculation of ecotoxicological impacts of heavy metals in the LCIA global approach. The aim of this paper is to understand how the spatial and dynamic characterization of life cycle inventory (LCI) data can be exploited in life cycle impact assessment and particularly for the evaluation of the aquatic and terrestrial ecotoxicity of Cr(VI). To quantify these impacts, we studied an industrial waste landfill in the North of France that was contaminated with chromium. On the polluted area, the aquatic contamination is due to the slag heap as well as to chromium spots in soil. The soil contamination is mainly due to infiltration of chromium from the infill. The concentration of Cr(VI) in soil and water varies according to seasonal climatic variations and groundwater level. These variations have an effect on the Cr(VI) fate factor, in particular on transfer and residence time of the substance. This study underlines the spatial distribution of aquatic ecotoxicity and the temporal variation of freshwater ecotoxicity. We analysed the correlation between precipitation, temperature, concentration and ecotoxicity impact. With regards to the terrestrial ecotoxicity, the study focused on the vertical variation of the ecotoxicity and the major role of the soil layer composition into terrestrial pollution.","Terrestrial and aquatic ecotoxicity assessment of Cr(VI) by the ReCiPe method calculation (LCIA): application on an old industrial contaminated site Abs: The most stable forms of chromium in the environment are chromium (III) and chromium (VI), the former being relatively immobile and necessary for organisms, and the latter being highly soluble and toxic. It is thus important to characterise ecotoxicological impacts of Cr(VI). However, there are still some important uncertainties in the calculation of ecotoxicological impacts of heavy metals in the LCIA global approach. The aim of this paper is to understand how the spatial and dynamic characterization of life cycle inventory (LCI) data can be exploited in life cycle impact assessment and particularly for the evaluation of the aquatic and terrestrial ecotoxicity of Cr(VI). To quantify these impacts, we studied an industrial waste landfill in the North of France that was contaminated with chromium. On the polluted area, the aquatic contamination is due to the slag heap as well as to chromium spots in soil. The soil contamination is mainly due to infiltration of chromium from the infill. The concentration of Cr(VI) in soil and water varies according to seasonal climatic variations and groundwater level. These variations have an effect on the Cr(VI) fate factor, in particular on transfer and residence time of the substance. This study underlines the spatial distribution of aquatic ecotoxicity and the temporal variation of freshwater ecotoxicity. We analysed the correlation between precipitation, temperature, concentration and ecotoxicity impact. With regards to the terrestrial ecotoxicity, the study focused on the vertical variation of the ecotoxicity and the major role of the soil layer composition into terrestrial pollution."
1509955,Fabregat-Cabello et al. 2012,Fast and accurate procedure for the determination of Cr(VI) in solid samples by isotope dilution mass spectrometry,"We present here a new environmental measurement method for the rapid extraction and accurate quantification of Cr(VI) in solid samples. The quantitative extraction of Cr(VI) is achieved in 10 minutes by means of focused microwave assisted extraction using 50 mmol/L Ethylendiamintetraacetic acid (EDTA) at pH 10 as extractant. In addition, it enables the separation of Cr species by anion exchange chromatography using a mobile phase which is a 1:10 dilution of the extracting solution. Thus, neutralization or acidification steps which are prone to cause interconversion of Cr species are not needed. Another benefit of using EDTA is that it allows to measure Cr(III)-EDTA complex and Cr(VI) simultaneously in an alkaline extraction solution. The application of a 10 minutes focused microwave assisted extraction (5 min at 90 °C plus 5 min at 110 °C) has been shown to quantitatively extract all forms of hexavalent chromium from the standard reference materials (SRM) candidate NIST 2700 and NIST 2701. A double spike isotope dilution mass spectrometry (IDMS) procedure was employed to study chromium interconversion reactions. It was observed that the formation of a Cr(III)-EDTA complex avoided Cr(III) oxidation for these two reference materials. Thus, the use of a double spiking strategy for quantification is not required and a single spike IDMS procedure using isotopically enriched Cr(VI) provided accurate results.","Fast and accurate procedure for the determination of Cr(VI) in solid samples by isotope dilution mass spectrometry Abs: We present here a new environmental measurement method for the rapid extraction and accurate quantification of Cr(VI) in solid samples. The quantitative extraction of Cr(VI) is achieved in 10 minutes by means of focused microwave assisted extraction using 50 mmol/L Ethylendiamintetraacetic acid (EDTA) at pH 10 as extractant. In addition, it enables the separation of Cr species by anion exchange chromatography using a mobile phase which is a 1:10 dilution of the extracting solution. Thus, neutralization or acidification steps which are prone to cause interconversion of Cr species are not needed. Another benefit of using EDTA is that it allows to measure Cr(III)-EDTA complex and Cr(VI) simultaneously in an alkaline extraction solution. The application of a 10 minutes focused microwave assisted extraction (5 min at 90 °C plus 5 min at 110 °C) has been shown to quantitatively extract all forms of hexavalent chromium from the standard reference materials (SRM) candidate NIST 2700 and NIST 2701. A double spike isotope dilution mass spectrometry (IDMS) procedure was employed to study chromium interconversion reactions. It was observed that the formation of a Cr(III)-EDTA complex avoided Cr(III) oxidation for these two reference materials. Thus, the use of a double spiking strategy for quantification is not required and a single spike IDMS procedure using isotopically enriched Cr(VI) provided accurate results."
1509954,Seidler et al. ,Systematic review and quantification of respiratory cancer risk for occupational exposure to hexavalent chromium,"AIM: To investigate the exposure-risk relationship for occupational chromium (VI) exposure and lung cancer in order to establish exposure limits. METHODS: We systematically searched for studies reporting on occupational Cr(VI) exposure and cancers of the respiratory tract. To be included, studies needed to provide data for more than one level of occupational Cr(VI) exposure, adequately consider the confounder smoking and be of adequate methodological quality. Because direct genotoxicity was considered the predominant mechanism of carcinogenesis of Cr(VI), linear models were applied in order to fit risk data. Relative risks were calculated based on these linear regression models and then used to estimate excess absolute risks. RESULTS: Five studies of two cohorts of chromium production workers in Baltimore, Maryland, and Painesville, Ohio, were included. Based on different estimates for the exposure effect, the absolute excess risk was found to be &quot;acceptable&quot; (less than 4 per 10,000 according to the German Committee on Hazardous Substances, &quot;AGS&quot;) at a Cr(VI) concentration of 0.1 ?g/m(3), and became &quot;intolerable&quot; (more than 4 per 1,000) beyond a Cr(VI) concentration of 1 ?g/m(3). CONCLUSION: Occupational exposure limits for Cr(VI) based on excess absolute risks can be derived from published data identified by a systematic literature review.","Systematic review and quantification of respiratory cancer risk for occupational exposure to hexavalent chromium Abs: AIM: To investigate the exposure-risk relationship for occupational chromium (VI) exposure and lung cancer in order to establish exposure limits. METHODS: We systematically searched for studies reporting on occupational Cr(VI) exposure and cancers of the respiratory tract. To be included, studies needed to provide data for more than one level of occupational Cr(VI) exposure, adequately consider the confounder smoking and be of adequate methodological quality. Because direct genotoxicity was considered the predominant mechanism of carcinogenesis of Cr(VI), linear models were applied in order to fit risk data. Relative risks were calculated based on these linear regression models and then used to estimate excess absolute risks. RESULTS: Five studies of two cohorts of chromium production workers in Baltimore, Maryland, and Painesville, Ohio, were included. Based on different estimates for the exposure effect, the absolute excess risk was found to be &quot;acceptable&quot; (less than 4 per 10,000 according to the German Committee on Hazardous Substances, &quot;AGS&quot;) at a Cr(VI) concentration of 0.1 ?g/m(3), and became &quot;intolerable&quot; (more than 4 per 1,000) beyond a Cr(VI) concentration of 1 ?g/m(3). CONCLUSION: Occupational exposure limits for Cr(VI) based on excess absolute risks can be derived from published data identified by a systematic literature review."
1509953,Fenner-Crisp 2012,Application of the International Life Sciences Institute Key Events Dose-Response Framework to food contaminants,"Contaminants are undesirable constituents in food. They may be formed during production of a processed food, present as a component in a source material, deliberately added to substitute for the proper substance, or the consequence of poor food-handling practices. Contaminants may be chemicals or pathogens. Chemicals generally degrade over time and become of less concern as a health threat. Pathogens have the ability to multiply, potentially resulting in an increased threat level. Formal structures have been lacking for systematically generating and evaluating hazard and exposure data for bioactive agents when problem situations arise. We need to know what the potential risk may be to determine whether intervention to reduce or eliminate contact with the contaminant is warranted. We need tools to aid us in assembling and assessing all available relevant information in an expeditious and scientifically sound manner. One such tool is the International Life Sciences Institute (ILSI) Key Events Dose-Response Framework (KEDRF). Developed as an extension of the WHO's International Program on Chemical Safety/ILSI mode of action/human relevance framework, it allows risk assessors to understand not only how a contaminant exerts its toxicity but also the dose response(s) for each key event and the ultimate outcome, including whether a threshold exists. This presentation will illustrate use of the KEDRF with case studies included in its development (chloroform and Listeriaonocytogenes) after its publication in the peer-reviewed scientific literature (chromium VI) and in a work in progress (3-monochloro-1, 2-propanediol).","Application of the International Life Sciences Institute Key Events Dose-Response Framework to food contaminants Abs: Contaminants are undesirable constituents in food. They may be formed during production of a processed food, present as a component in a source material, deliberately added to substitute for the proper substance, or the consequence of poor food-handling practices. Contaminants may be chemicals or pathogens. Chemicals generally degrade over time and become of less concern as a health threat. Pathogens have the ability to multiply, potentially resulting in an increased threat level. Formal structures have been lacking for systematically generating and evaluating hazard and exposure data for bioactive agents when problem situations arise. We need to know what the potential risk may be to determine whether intervention to reduce or eliminate contact with the contaminant is warranted. We need tools to aid us in assembling and assessing all available relevant information in an expeditious and scientifically sound manner. One such tool is the International Life Sciences Institute (ILSI) Key Events Dose-Response Framework (KEDRF). Developed as an extension of the WHO's International Program on Chemical Safety/ILSI mode of action/human relevance framework, it allows risk assessors to understand not only how a contaminant exerts its toxicity but also the dose response(s) for each key event and the ultimate outcome, including whether a threshold exists. This presentation will illustrate use of the KEDRF with case studies included in its development (chloroform and Listeriaonocytogenes) after its publication in the peer-reviewed scientific literature (chromium VI) and in a work in progress (3-monochloro-1, 2-propanediol)."
1509952,Tiersch et al. 2013,The role of culture media on embryonation and subsequent infectivity of Capillaria obsignata eggs,"This study investigated whether infectivity of Capillaria obsignata eggs depends on media culture used for embryonation. Intact female worms were kept in one of following four media: 0.5 % formalin, 2 % formalin, 0.1 % potassium dichromate and 0.1 N sulfuric acid. Embryonation rates of the eggs were quantified either daily in intact females for 16 days, or weekly in disrupted females. Infectivity of the embryonated eggs was tested through an experimental infection of chickens with a single dose of 250 eggs/ bird. The vast majority of the eggs (&gt;82 %) in the first two thirds of the uteri was able to complete embryonation, irrespective of the culture media used for incubation. However, only 32.6 % of total eggs could be harvested after disruption of the intact females. Embryonation rates of the eggs from disrupted worms were different among four culture media, with 0.1 N sulfuric acid resulting in the highest embryonation rate (44.2 %). All the experimentally infected birds harboured mature worms, with varying establishment rates depending on the culture media (P?&lt;?0.001). Incubation of the eggs in potassium dichromate 0.1 % resulted in a lower (P?&lt;?0.001) establishment rate (10.2 %) when compared with formalin (70.5 and 47.9 % for concentrations at 0.5 and 2 %, respectively) or with 0.1 N sulfuric acid (57.5 %). It can be concluded that most of the eggs in first two thirds of the uteri in the intact females have the potential to complete embryonation without being influenced by the culture media. However, disruption of the intact females results in lower number of harvestable embryonated eggs, with a considerable variation due to culture media used. With the exception of 0.1 % potassium dichromate, any of the three media, particularly 0.1 N sulfuric acid, can be suggested for embryonation of C. obsignata eggs.","The role of culture media on embryonation and subsequent infectivity of Capillaria obsignata eggs Abs: This study investigated whether infectivity of Capillaria obsignata eggs depends on media culture used for embryonation. Intact female worms were kept in one of following four media: 0.5 % formalin, 2 % formalin, 0.1 % potassium dichromate and 0.1 N sulfuric acid. Embryonation rates of the eggs were quantified either daily in intact females for 16 days, or weekly in disrupted females. Infectivity of the embryonated eggs was tested through an experimental infection of chickens with a single dose of 250 eggs/ bird. The vast majority of the eggs (&gt;82 %) in the first two thirds of the uteri was able to complete embryonation, irrespective of the culture media used for incubation. However, only 32.6 % of total eggs could be harvested after disruption of the intact females. Embryonation rates of the eggs from disrupted worms were different among four culture media, with 0.1 N sulfuric acid resulting in the highest embryonation rate (44.2 %). All the experimentally infected birds harboured mature worms, with varying establishment rates depending on the culture media (P?&lt;?0.001). Incubation of the eggs in potassium dichromate 0.1 % resulted in a lower (P?&lt;?0.001) establishment rate (10.2 %) when compared with formalin (70.5 and 47.9 % for concentrations at 0.5 and 2 %, respectively) or with 0.1 N sulfuric acid (57.5 %). It can be concluded that most of the eggs in first two thirds of the uteri in the intact females have the potential to complete embryonation without being influenced by the culture media. However, disruption of the intact females results in lower number of harvestable embryonated eggs, with a considerable variation due to culture media used. With the exception of 0.1 % potassium dichromate, any of the three media, particularly 0.1 N sulfuric acid, can be suggested for embryonation of C. obsignata eggs."
1509951,Monico et al. 2013,Degradation process of lead chromate in paintings by Vincent van Gogh studied by means of spectromicroscopic methods. 4. Artificial aging of model samples of co-precipitates of lead chromate and lead sulfate,"Previous investigations about the darkening of chrome yellow pigments revealed that this form of alteration is attributable to a reduction of the original Cr(VI) to Cr(III), and that the presence of sulfur-containing compounds, most often sulfates, plays a key role during this process. We recently demonstrated that different crystal forms of chrome yellow pigments (PbCrO(4) and PbCr(1-x)S(x)O(4)) are present in paintings by Vincent van Gogh. In the present work, we show how both the chemical composition and the crystalline structure of lead chromate-based pigments influence their stability. For this purpose, oil model samples made with in-house synthesized powders of PbCrO(4) and PbCr(1-x)S(x)O(4) were artificially aged and characterized. We observed a profound darkening only for those paint models made with PbCr(1-x)S(x)O(4), rich in SO(4)(2-) (x ? 0.4), and orthorhombic phases (&gt;30 wt %). Cr and S K-edge micro X-ray absorption near edge structure investigations revealed in an unequivocal manner the formation of up to about 60% of Cr(III)-species in the outer layer of the most altered samples; conversely, independent of the paint models' chemical composition, no change in the S-oxidation state was observed. Analyses employing UV-visible diffuse reflectance and Fourier transform infrared spectroscopy were performed on unaged and aged model samples in order to obtain additional information on the physicochemical changes induced by the aging treatment.","Degradation process of lead chromate in paintings by Vincent van Gogh studied by means of spectromicroscopic methods. 4. Artificial aging of model samples of co-precipitates of lead chromate and lead sulfate Abs: Previous investigations about the darkening of chrome yellow pigments revealed that this form of alteration is attributable to a reduction of the original Cr(VI) to Cr(III), and that the presence of sulfur-containing compounds, most often sulfates, plays a key role during this process. We recently demonstrated that different crystal forms of chrome yellow pigments (PbCrO(4) and PbCr(1-x)S(x)O(4)) are present in paintings by Vincent van Gogh. In the present work, we show how both the chemical composition and the crystalline structure of lead chromate-based pigments influence their stability. For this purpose, oil model samples made with in-house synthesized powders of PbCrO(4) and PbCr(1-x)S(x)O(4) were artificially aged and characterized. We observed a profound darkening only for those paint models made with PbCr(1-x)S(x)O(4), rich in SO(4)(2-) (x ? 0.4), and orthorhombic phases (&gt;30 wt %). Cr and S K-edge micro X-ray absorption near edge structure investigations revealed in an unequivocal manner the formation of up to about 60% of Cr(III)-species in the outer layer of the most altered samples; conversely, independent of the paint models' chemical composition, no change in the S-oxidation state was observed. Analyses employing UV-visible diffuse reflectance and Fourier transform infrared spectroscopy were performed on unaged and aged model samples in order to obtain additional information on the physicochemical changes induced by the aging treatment."
1509950,Monico et al. 2013,"Degradation process of lead chromate in paintings by Vincent van Gogh studied by means of spectromicroscopic methods. 3. Synthesis, characterization, and detection of different crystal forms of the chrome yellow pigment","The painter, Vincent van Gogh, and some of his contemporaries frequently made use of the pigment chrome yellow that is known to show a tendency toward darkening. This pigment may correspond to various chemical compounds such as PbCrO(4) and PbCr(1-x)S(x)O(4), that may each be present in various crystallographic forms with different tendencies toward degradation. Investigations by X-ray diffraction (XRD), mid-Fourier Transform infrared (FTIR), and Raman instruments (benchtop and portable) and synchrotron radiation-based micro-XRD and X-ray absorption near edge structure spectroscopy performed on oil-paint models, prepared with in-house synthesized PbCrO(4) and PbCr(1-x)S(x)O(4), permitted us to characterize the spectroscopic features of the various forms. On the basis of these results, an extended study has been carried out on historic paint tubes and on embedded paint microsamples taken from yellow-orange/pale yellow areas of 12 Van Gogh paintings, demonstrating that Van Gogh effectively made use of different chrome yellow types. This conclusion was also confirmed by in situ mid-FTIR investigations on Van Gogh's Portrait of Gauguin (Van Gogh Museum, Amsterdam).","Degradation process of lead chromate in paintings by Vincent van Gogh studied by means of spectromicroscopic methods. 3. Synthesis, characterization, and detection of different crystal forms of the chrome yellow pigment Abs: The painter, Vincent van Gogh, and some of his contemporaries frequently made use of the pigment chrome yellow that is known to show a tendency toward darkening. This pigment may correspond to various chemical compounds such as PbCrO(4) and PbCr(1-x)S(x)O(4), that may each be present in various crystallographic forms with different tendencies toward degradation. Investigations by X-ray diffraction (XRD), mid-Fourier Transform infrared (FTIR), and Raman instruments (benchtop and portable) and synchrotron radiation-based micro-XRD and X-ray absorption near edge structure spectroscopy performed on oil-paint models, prepared with in-house synthesized PbCrO(4) and PbCr(1-x)S(x)O(4), permitted us to characterize the spectroscopic features of the various forms. On the basis of these results, an extended study has been carried out on historic paint tubes and on embedded paint microsamples taken from yellow-orange/pale yellow areas of 12 Van Gogh paintings, demonstrating that Van Gogh effectively made use of different chrome yellow types. This conclusion was also confirmed by in situ mid-FTIR investigations on Van Gogh's Portrait of Gauguin (Van Gogh Museum, Amsterdam)."
1509949,Aluigi et al. 2012,Study on the adsorption of chromium (VI) by hydrolyzed keratin/polyamide 6 blend nanofibres,"In this study, nanofibre mats for chemical adsorption of heavy metals were prepared by electrospinning blends of hydrolyzed keratin (HK) and polyamide 6 (PA6) in formic acid. Viscosity measurements of the spinning solutions and morphological analyses of the fracture sections of the same polymer blends cast into films, suggested intermolecular interactions and good compatibility between HK and PA6. The mats made of continuous randomly oriented blend nanofilaments of HK/PA6 50/50 wt, with a mean diameter of about 200 nm, were tested as chromium (VI) ion adsorbents. The parameters investigated included initial chromium ion concentration, pH, contact time and adsorbent dosage. The maximum adsorption capacity occurred at acidic pH. The pseudo-first order, the pseudo-second order and the intraparticle diffusion models were used to describe the kinetics of adsorption process. It was found that kinetic data fit the pseudo-second order model and follow the intraparticle diffusion model, although diffusion is not the only rate control step. Adsorption data fit well the Freundlich isotherm model and the maximum adsorption capacity was found 55.9 mg/g. Moreover, the mean free energy (E) of adsorption ranges between 8 and 16 kJ/mol, so that the adsorption mechanism for HK-based nanofibres was explained as an ion-exchange process.","Study on the adsorption of chromium (VI) by hydrolyzed keratin/polyamide 6 blend nanofibres Abs: In this study, nanofibre mats for chemical adsorption of heavy metals were prepared by electrospinning blends of hydrolyzed keratin (HK) and polyamide 6 (PA6) in formic acid. Viscosity measurements of the spinning solutions and morphological analyses of the fracture sections of the same polymer blends cast into films, suggested intermolecular interactions and good compatibility between HK and PA6. The mats made of continuous randomly oriented blend nanofilaments of HK/PA6 50/50 wt, with a mean diameter of about 200 nm, were tested as chromium (VI) ion adsorbents. The parameters investigated included initial chromium ion concentration, pH, contact time and adsorbent dosage. The maximum adsorption capacity occurred at acidic pH. The pseudo-first order, the pseudo-second order and the intraparticle diffusion models were used to describe the kinetics of adsorption process. It was found that kinetic data fit the pseudo-second order model and follow the intraparticle diffusion model, although diffusion is not the only rate control step. Adsorption data fit well the Freundlich isotherm model and the maximum adsorption capacity was found 55.9 mg/g. Moreover, the mean free energy (E) of adsorption ranges between 8 and 16 kJ/mol, so that the adsorption mechanism for HK-based nanofibres was explained as an ion-exchange process."
1509948,Nandi et al. 2012,Ecotoxicological impact of sunlight assisted photoreduction of hexavalent chromium present in wastewater with zinc oxide nanoparticles on common Anabaena flos-aquae,"Hexavalent chromium is more toxic and carcinogenic compared to its trivalent counterpart. Hexavalent chromium can be photocatalytically reduced to trivalent one using zinc oxide semiconductor and solar or UV radiation as light source. But an important ecological aspect is whether the net toxicity decreases after the photocatalytic process. In the present work, we have selected Anabaena flos-aquae as the model organism and examined whether the net toxicity to which it has been exposed in water decreases after photocatalytic reduction of hexavalent chromium using ZnO semiconductor as photocatalyst. We have studied the cumulative toxicities of both chromium (before and after treatment) and ZnO (both nano and micro) separately and as a suspension of ZnO in chromium. Quantitative cell surface roughness analysis was conducted using AFM to confirm the changes in cell surface properties.","Ecotoxicological impact of sunlight assisted photoreduction of hexavalent chromium present in wastewater with zinc oxide nanoparticles on common Anabaena flos-aquae Abs: Hexavalent chromium is more toxic and carcinogenic compared to its trivalent counterpart. Hexavalent chromium can be photocatalytically reduced to trivalent one using zinc oxide semiconductor and solar or UV radiation as light source. But an important ecological aspect is whether the net toxicity decreases after the photocatalytic process. In the present work, we have selected Anabaena flos-aquae as the model organism and examined whether the net toxicity to which it has been exposed in water decreases after photocatalytic reduction of hexavalent chromium using ZnO semiconductor as photocatalyst. We have studied the cumulative toxicities of both chromium (before and after treatment) and ZnO (both nano and micro) separately and as a suspension of ZnO in chromium. Quantitative cell surface roughness analysis was conducted using AFM to confirm the changes in cell surface properties."
1509947,Tziritis et al. 2012,"Hexavalent chromium contamination in groundwaters of Thiva Basin, central Greece","There is an increasing concern regarding elevated levels of Cr(VI) in the environment due to its higher mobility and toxicity compared to the trivalent form. Anomalous hexavalent chromium concentrations (up to 212 ?g/L) were determined in irrigated groundwaters from the wider area of Thiva Basin (central Greece), frequently exceeding the permissible limit for human consumption (50 ?g/L for total Cr). Based on the spatial distribution of Cr(VI) values, two groups of groundwater samples were distinguished, possibly reflecting different natural and/or anthropogenic factors that govern the levels of contamination. The first group is spatially located northwards of Thiva town and is consisted of concentrations that range from 13 to 212 ?g/L (median 58 ?g/L), while the second group is located near Mouriki village and Cr(VI) values range from &lt;9 to 14 ?g/L. The Cr(VI) chemical anomalies represent an important social problem because the agricultural products of this region are a major vegetable supply for Greece, bringing up the urgent need to evaluate the health effects associated with Cr(VI) exposure by ingesting the potentially contaminated foods.","Hexavalent chromium contamination in groundwaters of Thiva Basin, central Greece Abs: There is an increasing concern regarding elevated levels of Cr(VI) in the environment due to its higher mobility and toxicity compared to the trivalent form. Anomalous hexavalent chromium concentrations (up to 212 ?g/L) were determined in irrigated groundwaters from the wider area of Thiva Basin (central Greece), frequently exceeding the permissible limit for human consumption (50 ?g/L for total Cr). Based on the spatial distribution of Cr(VI) values, two groups of groundwater samples were distinguished, possibly reflecting different natural and/or anthropogenic factors that govern the levels of contamination. The first group is spatially located northwards of Thiva town and is consisted of concentrations that range from 13 to 212 ?g/L (median 58 ?g/L), while the second group is located near Mouriki village and Cr(VI) values range from &lt;9 to 14 ?g/L. The Cr(VI) chemical anomalies represent an important social problem because the agricultural products of this region are a major vegetable supply for Greece, bringing up the urgent need to evaluate the health effects associated with Cr(VI) exposure by ingesting the potentially contaminated foods."
1509946,Kirman et al. 2012,Physiologically based pharmacokinetic model for rats and mice orally exposed to chromium,"A multi-compartment physiologically based pharmacokinetic (PBPK) model was developed to describe the behavior of Cr(III) and Cr(VI) in rats and mice following long-term oral exposure. Model compartments were included for GI lumen, oral mucosa, forestomach/stomach, small intestinal mucosa (duodenum, jejunum, ileum), blood, liver, kidney, bone, and a combined compartment for remaining tissues. Data from ex vivo Cr(VI) reduction studies were used to characterize reduction of Cr(VI) in fed rodent stomach fluid as a second-order, pH-dependent process. For model development, tissue time-course data for total chromium were collected from rats and mice exposed to Cr(VI) in drinking water for 90 days at six concentrations ranging from 0.1 to 180 mg Cr(VI)/L. These data were used to supplement the tissue time-course data collected in other studies with oral administration of Cr(III) and Cr(VI), including that from recent NTP chronic bioassays. Clear species differences were identified for chromium delivery to the target tissue (small intestines), with higher concentrations achieved in mice than in rats, consistent with small intestinal tumor formation, which was observed upon chronic exposures in mice but not in rats. Erythrocyte:plasma chromium ratios suggest that Cr(VI) entered portal circulation at drinking water concentrations equal to and greater than 60 mg/L in rodents. Species differences are described for distribution of chromium to the liver and kidney, with liver:kidney ratios higher in mice than in rats. Overall, the PBPK model provides a good description of chromium toxicokinetics, with model predictions for tissue chromium within a factor of 3 for greater than 80% of measurements evaluated. The tissue data and PBPK model predictions indicate a concentration gradient in the small intestines (duodenum &gt; jejunum &gt; ileum), which will be useful for assessing the tumor response gradient observed in mouse small intestines in terms of target tissue dose. The rodent PBPK model presented here, when used in conjunction with a human PBPK model for Cr(VI), should provide a more robust characterization of species differences in toxicokinetic factors for assessing the potential risks associated with low-dose exposures of Cr(VI) in human populations.","Physiologically based pharmacokinetic model for rats and mice orally exposed to chromium Abs: A multi-compartment physiologically based pharmacokinetic (PBPK) model was developed to describe the behavior of Cr(III) and Cr(VI) in rats and mice following long-term oral exposure. Model compartments were included for GI lumen, oral mucosa, forestomach/stomach, small intestinal mucosa (duodenum, jejunum, ileum), blood, liver, kidney, bone, and a combined compartment for remaining tissues. Data from ex vivo Cr(VI) reduction studies were used to characterize reduction of Cr(VI) in fed rodent stomach fluid as a second-order, pH-dependent process. For model development, tissue time-course data for total chromium were collected from rats and mice exposed to Cr(VI) in drinking water for 90 days at six concentrations ranging from 0.1 to 180 mg Cr(VI)/L. These data were used to supplement the tissue time-course data collected in other studies with oral administration of Cr(III) and Cr(VI), including that from recent NTP chronic bioassays. Clear species differences were identified for chromium delivery to the target tissue (small intestines), with higher concentrations achieved in mice than in rats, consistent with small intestinal tumor formation, which was observed upon chronic exposures in mice but not in rats. Erythrocyte:plasma chromium ratios suggest that Cr(VI) entered portal circulation at drinking water concentrations equal to and greater than 60 mg/L in rodents. Species differences are described for distribution of chromium to the liver and kidney, with liver:kidney ratios higher in mice than in rats. Overall, the PBPK model provides a good description of chromium toxicokinetics, with model predictions for tissue chromium within a factor of 3 for greater than 80% of measurements evaluated. The tissue data and PBPK model predictions indicate a concentration gradient in the small intestines (duodenum &gt; jejunum &gt; ileum), which will be useful for assessing the tumor response gradient observed in mouse small intestines in terms of target tissue dose. The rodent PBPK model presented here, when used in conjunction with a human PBPK model for Cr(VI), should provide a more robust characterization of species differences in toxicokinetic factors for assessing the potential risks associated with low-dose exposures of Cr(VI) in human populations."
1509945,Soudani et al. 2013,Oxidative stress-related lung dysfunction by chromium(VI): alleviation by Citrus aurantium L,"Chromium(VI), a very strong oxidant, causes high cytotoxicity through oxidative stress in tissue systems. Our study investigated the potential ability of ethanolic Citrus aurantium L., family Rutaceae extract, used as a nutritional supplement, to alleviate lung oxidative damage induced by Cr(VI). A high-performance liquid chromatography coupled with a mass spectrometer method was developed to separate and identify flavonoids in C. aurantium L. Six flavonoids were identified, as (1) poncirin, (2) naringin, (3) naringenin, (4) quercetin, (5) isosinensetin, and (6) tetramethyl-o-isoscutellarein. Adult Wistar rats, used in this study, were divided into six groups of six animals each: group I served as controls which received standard diet, group II received via drinking water K(2)Cr(2)O(7) alone (700 ppm), groups III and IV were pretreated for 10 days with ethanol extract of C. aurantium L. at doses of 100 and 300 mg/kg body weight/day, respectively, and then K(2)Cr(2)O(7) was administrated during 3 weeks, and groups V and VI received during 10 days only C. aurantium L. ethanol extract at doses of 100 and 300 mg/kg/day, respectively. Ethanol extract of C. aurantium L. was administered orally. Rats exposed to Cr(VI) showed in lung an increase in malondialdehyde and protein carbonyl levels and a decrease in sulflydryl content, glutathione, nonprotein thiol, and vitamins C and E levels. Decreases in enzyme activities such as in Na(+)K(+) ATPase, catalase, glutathione peroxidase, and superoxide dismutase were noted. Pretreatment with C. aurantium L. of chromium-treated rats ameliorated all biochemical parameters. Lung histological studies confirmed the biochemical parameters and the beneficial role of C. aurantium L.","Oxidative stress-related lung dysfunction by chromium(VI): alleviation by Citrus aurantium L Abs: Chromium(VI), a very strong oxidant, causes high cytotoxicity through oxidative stress in tissue systems. Our study investigated the potential ability of ethanolic Citrus aurantium L., family Rutaceae extract, used as a nutritional supplement, to alleviate lung oxidative damage induced by Cr(VI). A high-performance liquid chromatography coupled with a mass spectrometer method was developed to separate and identify flavonoids in C. aurantium L. Six flavonoids were identified, as (1) poncirin, (2) naringin, (3) naringenin, (4) quercetin, (5) isosinensetin, and (6) tetramethyl-o-isoscutellarein. Adult Wistar rats, used in this study, were divided into six groups of six animals each: group I served as controls which received standard diet, group II received via drinking water K(2)Cr(2)O(7) alone (700 ppm), groups III and IV were pretreated for 10 days with ethanol extract of C. aurantium L. at doses of 100 and 300 mg/kg body weight/day, respectively, and then K(2)Cr(2)O(7) was administrated during 3 weeks, and groups V and VI received during 10 days only C. aurantium L. ethanol extract at doses of 100 and 300 mg/kg/day, respectively. Ethanol extract of C. aurantium L. was administered orally. Rats exposed to Cr(VI) showed in lung an increase in malondialdehyde and protein carbonyl levels and a decrease in sulflydryl content, glutathione, nonprotein thiol, and vitamins C and E levels. Decreases in enzyme activities such as in Na(+)K(+) ATPase, catalase, glutathione peroxidase, and superoxide dismutase were noted. Pretreatment with C. aurantium L. of chromium-treated rats ameliorated all biochemical parameters. Lung histological studies confirmed the biochemical parameters and the beneficial role of C. aurantium L."
1509944,Castilleja-Rivera et al. 2012,Sensitive determination of chromium (VI) in paint samples using a membrane optode coupled to a multisyringe flow injection system,"In this work, the potential of a membrane optode coupled to a multisyringe flow injection system (MSFIA) was assessed for determining the Cr(VI) concentration in paint samples. The detection is based on the color obtained from the reaction of Cr(VI) with 1,5-diphenylcarbazide in the presence of sulfuric acid (H(2)SO(4)). The redox product was immobilized on a poly(styrene-divinylbenzene) (SDB-XC) membrane optode. The analyte in the sample was then directly quantified at the surface of the disk by measuring the intensity of reflected incident light using a bifurcated optical fiber at 540 nm. Experimental parameters (concentration of reagents, sample volume, flow rate of sample solutions, eluent concentration, and effect of diverse ions) were studied in detail. The overall time required for the complete procedure was 4 min and only required 0.2 mL of the sample volume. The dynamic working response of Cr(VI) was found within the concentration range of 2.4-1000 ?g L(-1) with a limit of detection (LOD) of 0.7 ?g L(-1), while the relative standard deviation (RSD) for 400 ?g L(-1) Cr(VI) was lower than 2% (n=6). This developed method was used to determine Cr(VI) concentrations in the paint samples, for which an alkaline extraction procedure was proposed. The extraction procedure was based on the use of a 7.5% Na(2)CO(3)/5% NaOH solution at 90 °C for 30 min. Under optimal conditions, the recoveries ranged from 99% to 101%. The complete method was validated using a certified reference material (ERA-QC540, soil sample) and by comparing the results with those obtained using atomic absorption spectrometry (AAS).","Sensitive determination of chromium (VI) in paint samples using a membrane optode coupled to a multisyringe flow injection system Abs: In this work, the potential of a membrane optode coupled to a multisyringe flow injection system (MSFIA) was assessed for determining the Cr(VI) concentration in paint samples. The detection is based on the color obtained from the reaction of Cr(VI) with 1,5-diphenylcarbazide in the presence of sulfuric acid (H(2)SO(4)). The redox product was immobilized on a poly(styrene-divinylbenzene) (SDB-XC) membrane optode. The analyte in the sample was then directly quantified at the surface of the disk by measuring the intensity of reflected incident light using a bifurcated optical fiber at 540 nm. Experimental parameters (concentration of reagents, sample volume, flow rate of sample solutions, eluent concentration, and effect of diverse ions) were studied in detail. The overall time required for the complete procedure was 4 min and only required 0.2 mL of the sample volume. The dynamic working response of Cr(VI) was found within the concentration range of 2.4-1000 ?g L(-1) with a limit of detection (LOD) of 0.7 ?g L(-1), while the relative standard deviation (RSD) for 400 ?g L(-1) Cr(VI) was lower than 2% (n=6). This developed method was used to determine Cr(VI) concentrations in the paint samples, for which an alkaline extraction procedure was proposed. The extraction procedure was based on the use of a 7.5% Na(2)CO(3)/5% NaOH solution at 90 °C for 30 min. Under optimal conditions, the recoveries ranged from 99% to 101%. The complete method was validated using a certified reference material (ERA-QC540, soil sample) and by comparing the results with those obtained using atomic absorption spectrometry (AAS)."
1509943,Chen and  Ren 2012,"Sensitive determination of chromium (VI) based on the inner filter effect of upconversion luminescent nanoparticles (NaYF4:Yb3+, Er3+)","A new method was developed for selective and sensitive determination of trace chromium (VI) based on the inner filter effect (IFE) of upconversion luminescent nanoparticles (NaYF(4):Yb(3+), Er(3+)) as fluorescence probes. In this study, water-soluble and well dispersible upconversion luminescent nanoparticles (NaYF(4):Yb(3+), Er(3+)) were firstly synthesized by hydrothermal method, and characterized by transmission electron microscopy (TEM) and luminescence spectroscopy. And then, the IFE method was established for determination of chromium (VI). The principle of this assay is based on the complementary overlap of the green emission band of nanoparticles (NaYF(4):Yb(3+), Er(3+)) with the absorption spectrum of a pink chelate complex (Cr(III)-diphenylcarbazone), which was generated by the quantitative reaction between diphenylcarbazide (DPC) and Cr(VI) in mineral acid solution. Under the optimal condition, the decrease in the upconversion luminescent nanoparticles was proportional to the concentration of chromium (VI) due to IFE. The linear range is 0.070-10.0×10(-6) mol L(-1) Cr(VI), and the limit of detection (3?) is 2.40×10(-8) mol L(-1) Cr(VI). The method described here is sensitive than the method of spectrophotometry. This assay was used in the determination of Cr(VI) in water samples.","Sensitive determination of chromium (VI) based on the inner filter effect of upconversion luminescent nanoparticles (NaYF4:Yb3+, Er3+) Abs: A new method was developed for selective and sensitive determination of trace chromium (VI) based on the inner filter effect (IFE) of upconversion luminescent nanoparticles (NaYF(4):Yb(3+), Er(3+)) as fluorescence probes. In this study, water-soluble and well dispersible upconversion luminescent nanoparticles (NaYF(4):Yb(3+), Er(3+)) were firstly synthesized by hydrothermal method, and characterized by transmission electron microscopy (TEM) and luminescence spectroscopy. And then, the IFE method was established for determination of chromium (VI). The principle of this assay is based on the complementary overlap of the green emission band of nanoparticles (NaYF(4):Yb(3+), Er(3+)) with the absorption spectrum of a pink chelate complex (Cr(III)-diphenylcarbazone), which was generated by the quantitative reaction between diphenylcarbazide (DPC) and Cr(VI) in mineral acid solution. Under the optimal condition, the decrease in the upconversion luminescent nanoparticles was proportional to the concentration of chromium (VI) due to IFE. The linear range is 0.070-10.0×10(-6) mol L(-1) Cr(VI), and the limit of detection (3?) is 2.40×10(-8) mol L(-1) Cr(VI). The method described here is sensitive than the method of spectrophotometry. This assay was used in the determination of Cr(VI) in water samples."
1509942,Koh et al. 2011,Cancer mortality and incidence in cement industry workers in Korea,"<strong>OBJECTIVES: </strong>Cement contains hexavalent chromium, which is a human carcinogen. However, its effect on cancer seems inconclusive in epidemiologic studies. The aim of this retrospective cohort study was to elucidate the association between dust exposure in the cement industry and cancer occurrence.<br /><br /><strong>METHODS: </strong>The cohorts consisted of male workers in 6 Portland cement factories in Korea. Study subjects were classified into five groups by job: quarry, production, maintenance, laboratory, and office work. Cancer mortality and incidence in workers were observed from 1992 to 2007 and 1997-2005, respectively. Standardized mortality ratios and standardized incidence ratios were calculated according to the five job classifications.<br /><br /><strong>RESULTS: </strong>There was an increased standardized incidence ratio for stomach cancer of 1.56 (27/17.36, 95% confidence interval: 1.02-2.26) in production workers. The standardized mortality ratio for lung cancer increased in production workers. However, was not statistically significant.<br /><br /><strong>CONCLUSION: </strong>Our result suggests a potential association between cement exposure and stomach cancer. Hexavalent chromium contained in cement might be a causative carcinogen.","Cancer mortality and incidence in cement industry workers in Korea Abs: <strong>OBJECTIVES: </strong>Cement contains hexavalent chromium, which is a human carcinogen. However, its effect on cancer seems inconclusive in epidemiologic studies. The aim of this retrospective cohort study was to elucidate the association between dust exposure in the cement industry and cancer occurrence.<br /><br /><strong>METHODS: </strong>The cohorts consisted of male workers in 6 Portland cement factories in Korea. Study subjects were classified into five groups by job: quarry, production, maintenance, laboratory, and office work. Cancer mortality and incidence in workers were observed from 1992 to 2007 and 1997-2005, respectively. Standardized mortality ratios and standardized incidence ratios were calculated according to the five job classifications.<br /><br /><strong>RESULTS: </strong>There was an increased standardized incidence ratio for stomach cancer of 1.56 (27/17.36, 95% confidence interval: 1.02-2.26) in production workers. The standardized mortality ratio for lung cancer increased in production workers. However, was not statistically significant.<br /><br /><strong>CONCLUSION: </strong>Our result suggests a potential association between cement exposure and stomach cancer. Hexavalent chromium contained in cement might be a causative carcinogen."
1509941,Franzellitti et al. 2012,Molecular and cellular effects induced by hexavalent chromium in Mediterranean mussels,"The present study evaluated the effects of Cr(VI) in digestive gland of the Mediterranean mussel (Mytilus galloprovincialis) exposed for 1 week to the metal at 1, 10, and 50 ng/L. Tissue accumulation of Cr and lysosomal biomarkers were measured. Moreover, a low-density DNA microarray was used to identify early molecular markers of metal exposure. A concentration-dependent increase in tissue Cr concentrations was observed in both digestive gland and remaining soft tissues. A reduction of lysosomal membrane stability was detected in digestive gland at 10 and 50 ng/L of Cr(VI), indicating a loss of cell functional integrity. The expression of mRNAs encoding 13 genes involved in metal resistance (mt10, mt20), molecular chaperoning (hsp70), immune response (mytlB, mytcA and lys), transcriptional (histones h1, h2-a and h4), and antioxidant/detoxification (cat, mrp2, mvp) processes were significantly altered already at the lowest Cr(VI) concentration, where the effects at the histological level were nonsignificant. Altogether, data point out that depending on the exposure concentration Cr(VI) may cause or not oxidative stress altering the efficiency of the antioxidant system in counteracting the effects of Cr as a redox-active metal. Moreover, changes of mRNA expression profiles induced by Cr(VI) concentrations as low as 1-50 ng/L were related to altered immunomodulation, DNA stability, and stress response pathways previously proven to be affected by the metal. The molecular targets presently identified may drive the development of new biomarkers for Cr exposure or help their interpretation.","Molecular and cellular effects induced by hexavalent chromium in Mediterranean mussels Abs: The present study evaluated the effects of Cr(VI) in digestive gland of the Mediterranean mussel (Mytilus galloprovincialis) exposed for 1 week to the metal at 1, 10, and 50 ng/L. Tissue accumulation of Cr and lysosomal biomarkers were measured. Moreover, a low-density DNA microarray was used to identify early molecular markers of metal exposure. A concentration-dependent increase in tissue Cr concentrations was observed in both digestive gland and remaining soft tissues. A reduction of lysosomal membrane stability was detected in digestive gland at 10 and 50 ng/L of Cr(VI), indicating a loss of cell functional integrity. The expression of mRNAs encoding 13 genes involved in metal resistance (mt10, mt20), molecular chaperoning (hsp70), immune response (mytlB, mytcA and lys), transcriptional (histones h1, h2-a and h4), and antioxidant/detoxification (cat, mrp2, mvp) processes were significantly altered already at the lowest Cr(VI) concentration, where the effects at the histological level were nonsignificant. Altogether, data point out that depending on the exposure concentration Cr(VI) may cause or not oxidative stress altering the efficiency of the antioxidant system in counteracting the effects of Cr as a redox-active metal. Moreover, changes of mRNA expression profiles induced by Cr(VI) concentrations as low as 1-50 ng/L were related to altered immunomodulation, DNA stability, and stress response pathways previously proven to be affected by the metal. The molecular targets presently identified may drive the development of new biomarkers for Cr exposure or help their interpretation."
1509940,Guo et al. 2012,Reduction of Cr(VI) by Escherichia coli BL21 in the presence of redox mediators,"Anthraquinone-2,7-disulfonate (2,7-AQDS), anthraquinone-1-sulfonate (?-AQS), anthraquinone-2-sulfonate (AQS), anthraquinone-2,6-disulfonate (AQDS) and anthraquinone-1,5-disulfonate (1,5-AQDS) were selected as redox mediators for Cr(VI) reduction by Escherichia coli BL21. In the presence of 0.8mmoll(-1) AQS, the Cr(VI) reduction efficiency was 98.5% in 7.5h, whereas it was only 21-34% in the absence of a mediator or in the presence of ?-AQS, 1,5-AQDS, AQDS, 2,7-AQDS. A linear correlation, k=0.768C(AQS)+1.5531 (R(2)=0.9935), was found for the reaction constant, k (mg Cr(VI) g(-1) dry cell weight h(-1)) and the AQS concentration (C(AQS)). The Arrhenius equation described the Cr(VI) reduction in the tested temperature range, and the pre-exponential factor A was 13.249mg Cr(VI) g(-1) dry cell weight h(-1),and the activation energy Ea was 28.01kJmol(-1). Glucose was the best carbon sources, and the optimum pH was 6.0. The Cr(VI) reduction rate obtained with AQS is a significant improvement over low conventional anaerobic reduction rates.","Reduction of Cr(VI) by Escherichia coli BL21 in the presence of redox mediators Abs: Anthraquinone-2,7-disulfonate (2,7-AQDS), anthraquinone-1-sulfonate (?-AQS), anthraquinone-2-sulfonate (AQS), anthraquinone-2,6-disulfonate (AQDS) and anthraquinone-1,5-disulfonate (1,5-AQDS) were selected as redox mediators for Cr(VI) reduction by Escherichia coli BL21. In the presence of 0.8mmoll(-1) AQS, the Cr(VI) reduction efficiency was 98.5% in 7.5h, whereas it was only 21-34% in the absence of a mediator or in the presence of ?-AQS, 1,5-AQDS, AQDS, 2,7-AQDS. A linear correlation, k=0.768C(AQS)+1.5531 (R(2)=0.9935), was found for the reaction constant, k (mg Cr(VI) g(-1) dry cell weight h(-1)) and the AQS concentration (C(AQS)). The Arrhenius equation described the Cr(VI) reduction in the tested temperature range, and the pre-exponential factor A was 13.249mg Cr(VI) g(-1) dry cell weight h(-1),and the activation energy Ea was 28.01kJmol(-1). Glucose was the best carbon sources, and the optimum pH was 6.0. The Cr(VI) reduction rate obtained with AQS is a significant improvement over low conventional anaerobic reduction rates."
1509939,Samuel et al. 2012,Persistent hexavalent chromium exposure impaired the pubertal development and ovarian histoarchitecture in wistar rat offspring,"Hexavalent chromium (CrVI) is a highly toxic metal and a major environmental pollutant. Several studies indicate that CrVI exposure adversely affects reproductive function. We reported that maternal Cr exposure resulted in Cr accumulation in the reproductive organs of female offsprings. CrVI can cross the placental barrier and also can be passed through breastfeeding. The present investigation aimed to determine the persistent (in utero through puberal period) CrVI exposure-induced toxic effects on the reproductive functions of mother and the offspring. Induction of oxidative stress is one of the plausible mechanisms behind Cr-induced cellular deteriorations. Mother rats exposed to CrVI showed reduced reproductive outcome, while the offsprings showed higher accumulation of Cr in ovary, altered steroid, and peptide hormones. Specific activities of antioxidant enzymes were decreased and associated with increased levels of H(2) O(2) , and lipid peroxidation. CrVI exposure also damaged the ovarian histoarchitecture in various age groups studied. CrVI exposure also delayed the sexual maturation. Results from the present investigation suggest that CrVI exposure from in utero through puberal period significantly damaged the pubertal development through altered antioxidants, anemia, and altered hormone levels. These changes were associated with damaged ovarian histoarchitecture and extended estrous cycle in developing Wistar rats. © 2012 Wiley Periodicals, Inc. Environ Toxicol, 2012.","Persistent hexavalent chromium exposure impaired the pubertal development and ovarian histoarchitecture in wistar rat offspring Abs: Hexavalent chromium (CrVI) is a highly toxic metal and a major environmental pollutant. Several studies indicate that CrVI exposure adversely affects reproductive function. We reported that maternal Cr exposure resulted in Cr accumulation in the reproductive organs of female offsprings. CrVI can cross the placental barrier and also can be passed through breastfeeding. The present investigation aimed to determine the persistent (in utero through puberal period) CrVI exposure-induced toxic effects on the reproductive functions of mother and the offspring. Induction of oxidative stress is one of the plausible mechanisms behind Cr-induced cellular deteriorations. Mother rats exposed to CrVI showed reduced reproductive outcome, while the offsprings showed higher accumulation of Cr in ovary, altered steroid, and peptide hormones. Specific activities of antioxidant enzymes were decreased and associated with increased levels of H(2) O(2) , and lipid peroxidation. CrVI exposure also damaged the ovarian histoarchitecture in various age groups studied. CrVI exposure also delayed the sexual maturation. Results from the present investigation suggest that CrVI exposure from in utero through puberal period significantly damaged the pubertal development through altered antioxidants, anemia, and altered hormone levels. These changes were associated with damaged ovarian histoarchitecture and extended estrous cycle in developing Wistar rats. © 2012 Wiley Periodicals, Inc. Environ Toxicol, 2012."
1509938,Okello et al. 2012,Reduction of hexavalent chromium using naturally-derived flavonoids,"Quercetin is a naturally occurring flavonoid that is known to form complexes with metals; a process that reduces the environmental availability of toxic metals such as chromium. We hereby report the first evidence of the removal of Cr(VI) from environmental samples using quercetin (QCR) and two synthetic derivatives: namely quercetin pentaphosphate (QPP) and quercetin sulfonic acid (QSA). We successfully synthesized both QPP and QSA using simple procedures while characterizing them with UV-vis spectroscopy, H(1)-NMR, (13)C NMR, (31)P-NMR, and LC-MS techniques. The solubility of QPP was found to be 840 mg/mL and aqueous solutions of both QPP and QSA were stable for over a period of 1 year. Quercetin and these derivatives were subsequently utilized for the reduction of Cr(VI) and QCR was found to have a higher reduction efficiency of 99.8% (30 min), followed by QPP/palladium nanoparticles mixture (PdNPs) at 96.5% (60 min), and finally QSA/PdNPs mixtures at 91.7% (60 min). PdNPs catalyst increased the efficiency by ?36.5% while a change in operating temperature from 25 to 45 °C improved the efficiency by ?46.8%. Electron paramagnetic resonance spectroscopy was used to confirm the presence of Cr (III) in the reaction products. This reduction approach was validated in environmental (Binghamton University) BU and standard reference material (BRS) soil samples. Results showed that the analysis could be completed within one hour and the efficiency was higher in BU soil than in BRS soil by 16.1%. QPP registered the highest % atom economy of 94.6%. This indicates enhanced performance compared to bioremediation approach that requires several months to achieve about 90% reduction efficiency.","Reduction of hexavalent chromium using naturally-derived flavonoids Abs: Quercetin is a naturally occurring flavonoid that is known to form complexes with metals; a process that reduces the environmental availability of toxic metals such as chromium. We hereby report the first evidence of the removal of Cr(VI) from environmental samples using quercetin (QCR) and two synthetic derivatives: namely quercetin pentaphosphate (QPP) and quercetin sulfonic acid (QSA). We successfully synthesized both QPP and QSA using simple procedures while characterizing them with UV-vis spectroscopy, H(1)-NMR, (13)C NMR, (31)P-NMR, and LC-MS techniques. The solubility of QPP was found to be 840 mg/mL and aqueous solutions of both QPP and QSA were stable for over a period of 1 year. Quercetin and these derivatives were subsequently utilized for the reduction of Cr(VI) and QCR was found to have a higher reduction efficiency of 99.8% (30 min), followed by QPP/palladium nanoparticles mixture (PdNPs) at 96.5% (60 min), and finally QSA/PdNPs mixtures at 91.7% (60 min). PdNPs catalyst increased the efficiency by ?36.5% while a change in operating temperature from 25 to 45 °C improved the efficiency by ?46.8%. Electron paramagnetic resonance spectroscopy was used to confirm the presence of Cr (III) in the reaction products. This reduction approach was validated in environmental (Binghamton University) BU and standard reference material (BRS) soil samples. Results showed that the analysis could be completed within one hour and the efficiency was higher in BU soil than in BRS soil by 16.1%. QPP registered the highest % atom economy of 94.6%. This indicates enhanced performance compared to bioremediation approach that requires several months to achieve about 90% reduction efficiency."
1509937,Li et al. 2012,Fabrication of polypyrrole/graphene oxide composite nanosheets and their applications for Cr(VI) removal in aqueous solution,"In this paper, we report on the simple, reliable synthesis of polypyrrole (PPy)/graphene oxide (GO) composite nanosheets by using sacrificial-template polymerization method. Herein, MnO(2) nanoslices were chosen as a sacrificial-template to deposit PPy, which served as the oxidant as well. During the polymerization of pyrrole on surface of GO nanosheets, MnO(2) component was consumed incessantly. As a result, the PPy growing on the surface of GO nanosheets has the morphology just like the MnO(2) nanoslices. This method can provide the fabrication of PPy nanostructures more easily than conventional route due to its independence of removing template, which usually is a complex and tedious experimental process. The as-prepared PPy/GO composite nanosheets exhibited an enhanced properties for Cr(VI) ions removal in aqueous solution based on the synergy effect. The adsorption capacity of the PPy/GO composite nanosheets is about two times as large as that of conventional PPy nanoparticles. We believe that our findings can open a new and effective avenue to improve the adsorption performance in removing heavy metal ions from waste water.","Fabrication of polypyrrole/graphene oxide composite nanosheets and their applications for Cr(VI) removal in aqueous solution Abs: In this paper, we report on the simple, reliable synthesis of polypyrrole (PPy)/graphene oxide (GO) composite nanosheets by using sacrificial-template polymerization method. Herein, MnO(2) nanoslices were chosen as a sacrificial-template to deposit PPy, which served as the oxidant as well. During the polymerization of pyrrole on surface of GO nanosheets, MnO(2) component was consumed incessantly. As a result, the PPy growing on the surface of GO nanosheets has the morphology just like the MnO(2) nanoslices. This method can provide the fabrication of PPy nanostructures more easily than conventional route due to its independence of removing template, which usually is a complex and tedious experimental process. The as-prepared PPy/GO composite nanosheets exhibited an enhanced properties for Cr(VI) ions removal in aqueous solution based on the synergy effect. The adsorption capacity of the PPy/GO composite nanosheets is about two times as large as that of conventional PPy nanoparticles. We believe that our findings can open a new and effective avenue to improve the adsorption performance in removing heavy metal ions from waste water."
1509936,Ge et al. 2013,Distinct and effective biotransformation of hexavalent chromium by a novel isolate under aerobic growth followed by facultative anaerobic incubation,"A bacterial isolate (G161) with high Cr(VI)-reducing capacity was isolated from Cr(VI)-contaminated soil and identified as Leucobacter sp. on the basis of 16S rRNA gene sequence analysis. The isolate was a Gram-positive, aerobic rod. The hexavalent chromate-reducing capability of the isolate was investigated under three conditions of oxygen stress. The isolate was found to reduce Cr(VI) under all conditions but performed most effectively during aerobic growth followed by facultative anaerobic incubation. Under these conditions, the isolate tolerated K(2)Cr(2)O(7) concentrations up to 1,000 mg/l and completely reduced 400 mg/l K(2)Cr(2)O(7) within 96 h. The strain reduced Cr(VI) over a wide range of pH (6.0-11.0) and temperatures (15-45 °C) with optimum performance at pH?8.0 and 35 °C. The presence of other metals, such as Ca(2+), Co(2+), Cu(2+), Mn(2+), Ni(2+), and Zn(2+), induced no effect or else played a stimulatory role on Cr(VI)-reduction activity of the strain. The strain was tested for Cr(VI) removal in wastewaters and proved capable of completely reducing the contained Cr(VI). This is the novel report of a bacterial growth and Cr(VI)-reduction process under sequential aerobic growth and facultative anaerobic conditions. The study suggested that the isolate possesses a distinct capability for Cr(VI) reduction which could be harnessed for the detoxification of chromate-contaminated wastewaters.","Distinct and effective biotransformation of hexavalent chromium by a novel isolate under aerobic growth followed by facultative anaerobic incubation Abs: A bacterial isolate (G161) with high Cr(VI)-reducing capacity was isolated from Cr(VI)-contaminated soil and identified as Leucobacter sp. on the basis of 16S rRNA gene sequence analysis. The isolate was a Gram-positive, aerobic rod. The hexavalent chromate-reducing capability of the isolate was investigated under three conditions of oxygen stress. The isolate was found to reduce Cr(VI) under all conditions but performed most effectively during aerobic growth followed by facultative anaerobic incubation. Under these conditions, the isolate tolerated K(2)Cr(2)O(7) concentrations up to 1,000 mg/l and completely reduced 400 mg/l K(2)Cr(2)O(7) within 96 h. The strain reduced Cr(VI) over a wide range of pH (6.0-11.0) and temperatures (15-45 °C) with optimum performance at pH?8.0 and 35 °C. The presence of other metals, such as Ca(2+), Co(2+), Cu(2+), Mn(2+), Ni(2+), and Zn(2+), induced no effect or else played a stimulatory role on Cr(VI)-reduction activity of the strain. The strain was tested for Cr(VI) removal in wastewaters and proved capable of completely reducing the contained Cr(VI). This is the novel report of a bacterial growth and Cr(VI)-reduction process under sequential aerobic growth and facultative anaerobic conditions. The study suggested that the isolate possesses a distinct capability for Cr(VI) reduction which could be harnessed for the detoxification of chromate-contaminated wastewaters."
1509935,León-Torres et al. 2012,On the use of a natural peat for the removal of Cr(VI) from aqueous solutions,"A natural peat has been used as an adsorbent for the removal of hexavalent chromium from aqueous solution. The peat was firstly characterized in terms of particle size and chemical composition (ash content, pH of the point of zero charge, FT-IR and thermal analysis). Next, the kinetic and equilibrium aspects of the adsorption of Cr(VI) by this adsorbent were studied. The kinetic data were satisfactorily fitted to a kinetic law of partial order in C equal to one. The specific adsorption rates are around 10(-4)s(-1), increasing as temperature does. A noticeable influence of diffusion on the global adsorption process has been demonstrated. Finally, the equilibrium isotherms were satisfactorily fitted to a previously proposed model. The adsorption capacity of Cr(VI) was similar to some other previously reported and the affinity of Cr(VI) towards the active sites of the adsorbent increases as temperature rises.","On the use of a natural peat for the removal of Cr(VI) from aqueous solutions Abs: A natural peat has been used as an adsorbent for the removal of hexavalent chromium from aqueous solution. The peat was firstly characterized in terms of particle size and chemical composition (ash content, pH of the point of zero charge, FT-IR and thermal analysis). Next, the kinetic and equilibrium aspects of the adsorption of Cr(VI) by this adsorbent were studied. The kinetic data were satisfactorily fitted to a kinetic law of partial order in C equal to one. The specific adsorption rates are around 10(-4)s(-1), increasing as temperature does. A noticeable influence of diffusion on the global adsorption process has been demonstrated. Finally, the equilibrium isotherms were satisfactorily fitted to a previously proposed model. The adsorption capacity of Cr(VI) was similar to some other previously reported and the affinity of Cr(VI) towards the active sites of the adsorbent increases as temperature rises."
1509934,Sharma et al. 2012,Genetic predisposition for dermal problems in hexavalent chromium exposed population,"We studied the effect of genetic susceptibility on hexavalent chromium induced dermal adversities. The health status of population was examined from the areas of Kanpur (India) having the elevated hexavalent chromium levels in groundwater. Blood samples were collected for DNA isolation to conduct polymorphic determination of genes, namely: NQO1 (C609T), hOGG1 (C1245G), GSTT1, and GSTM1 (deletion). Symptomatic exposed subjects (n = 38) were compared with asymptomatic exposed subjects (n = 108) along with asymptomatic controls (n = 148) from a non contaminated reference community. Exposed symptomatic group consisted of 36.8% subjects who were GSTM1 null genotyped as compared to asymptomatic where only 19.4% subjects were null. The exposed subjects with GSTM1 null genotype were more susceptible to dermal adversities in comparison with wild genotyped subjects (OR?=?2.42; 95% CI?=?1.071-5.451). Age, smoking, gender or duration of residence were not found to have any confounding effect towards this association. Association with other genes was not statistically significant, nonetheless, possible contribution by these genes cannot be ruled out. In conclusion, variation in the polymorphic status of GSTM1 gene may influence dermal outcomes among residents from Cr(VI) contaminated areas. Further studies are therefore, needed to examine these observations among different population groups.","Genetic predisposition for dermal problems in hexavalent chromium exposed population Abs: We studied the effect of genetic susceptibility on hexavalent chromium induced dermal adversities. The health status of population was examined from the areas of Kanpur (India) having the elevated hexavalent chromium levels in groundwater. Blood samples were collected for DNA isolation to conduct polymorphic determination of genes, namely: NQO1 (C609T), hOGG1 (C1245G), GSTT1, and GSTM1 (deletion). Symptomatic exposed subjects (n = 38) were compared with asymptomatic exposed subjects (n = 108) along with asymptomatic controls (n = 148) from a non contaminated reference community. Exposed symptomatic group consisted of 36.8% subjects who were GSTM1 null genotyped as compared to asymptomatic where only 19.4% subjects were null. The exposed subjects with GSTM1 null genotype were more susceptible to dermal adversities in comparison with wild genotyped subjects (OR?=?2.42; 95% CI?=?1.071-5.451). Age, smoking, gender or duration of residence were not found to have any confounding effect towards this association. Association with other genes was not statistically significant, nonetheless, possible contribution by these genes cannot be ruled out. In conclusion, variation in the polymorphic status of GSTM1 gene may influence dermal outcomes among residents from Cr(VI) contaminated areas. Further studies are therefore, needed to examine these observations among different population groups."
1509933,Xing-Run et al. 2012,Effect and removal mechanisms of 6 different washing agents for building wastes containing chromium,"With the building wastes contaminated by chromium in Haibei Chemical Plan in China as objects, we studied the contents of total Cr and Cr (VI) of different sizes, analyzed the effect of 6 different washing agents, discussed the removal mechanisms of 6 different washing agents for Cr in various forms, and finally selected applicable washing agent. As per the results, particle size had little impact on the contents of total Cr and Cr (VI); after one washing with water, the removal rate of total Cr and Cr (VI) was 75% and 78%, respectively, and after the second washing with 6 agents, the removal rate of citric acid was the highest, above 90% for total Cr and above 99% for hexavalent chromium; the pH of building wastes were reduced by citric acid, and under acid condition, hexavalent chromium was reduced to trivalent chromium spontaneously by organic acid, which led to better removal rate of acid soluble Cr and reducible Cr; due to the complexing action, citric acid had best removal rate for oxidizable trivalent chromium. In conclusion, citric acid is the most applicable second washing agent for building wastes.","Effect and removal mechanisms of 6 different washing agents for building wastes containing chromium Abs: With the building wastes contaminated by chromium in Haibei Chemical Plan in China as objects, we studied the contents of total Cr and Cr (VI) of different sizes, analyzed the effect of 6 different washing agents, discussed the removal mechanisms of 6 different washing agents for Cr in various forms, and finally selected applicable washing agent. As per the results, particle size had little impact on the contents of total Cr and Cr (VI); after one washing with water, the removal rate of total Cr and Cr (VI) was 75% and 78%, respectively, and after the second washing with 6 agents, the removal rate of citric acid was the highest, above 90% for total Cr and above 99% for hexavalent chromium; the pH of building wastes were reduced by citric acid, and under acid condition, hexavalent chromium was reduced to trivalent chromium spontaneously by organic acid, which led to better removal rate of acid soluble Cr and reducible Cr; due to the complexing action, citric acid had best removal rate for oxidizable trivalent chromium. In conclusion, citric acid is the most applicable second washing agent for building wastes."
1509932,Adki et al. 2013,"Nopalea cochenillifera, a potential chromium (VI) hyperaccumulator plant","Hexavalant chromium [Cr(VI)] tolerance and accumulation in in vitro grown Nopalea cochenillifera Salm. Dyck. plants was investigated. A micropropagation protocol was establish for a rapid multiplication of N. cochenillifera and [Cr(VI)] tolerance and accumulation was studied in in vitro grown cultures. Cr concentration was estimated by atomic absorption spectroscopy in roots and shoots to confirm plant's hyperaccumulation capacity. Plants showed tolerance up to 100 ?M K(2)Cr(2)O(7) without any significant changes in root growth after 16 days treatment; whereas, chlorophyll content in plants treated with 1 and 10 ?M K(2)Cr(2)O(7) were not so different than the control plant. The levels of lipid peroxidation and protein oxidation increased significantly (p &lt; 0.01) with increasing concentration of chromium. Exposures of N. cochenillifera to lower concentrations of K(2)Cr(2)O(7) (? 10 ?M) induced catalase (CAT) and superoxide dismutase (SOD) significantly (p &lt; 0.001) but higher concentrations of K(2)Cr(2)O(7) (&gt;100 ?M) inhibited the activities of CAT and SOD. Roots accumulated a maximum of 25,263.396 ± 1,722.672 mg Cr Kg(-1) dry weight (DW); while the highest concentration of Cr in N. cochenillifera shoots was 705.714 ± 32.324 mg Cr Kg(-1) DW. N. cochenillifera could be a prospective hyperaccumulator plant of Cr(VI) and a promising candidate for phytoremediation purposes.","Nopalea cochenillifera, a potential chromium (VI) hyperaccumulator plant Abs: Hexavalant chromium [Cr(VI)] tolerance and accumulation in in vitro grown Nopalea cochenillifera Salm. Dyck. plants was investigated. A micropropagation protocol was establish for a rapid multiplication of N. cochenillifera and [Cr(VI)] tolerance and accumulation was studied in in vitro grown cultures. Cr concentration was estimated by atomic absorption spectroscopy in roots and shoots to confirm plant's hyperaccumulation capacity. Plants showed tolerance up to 100 ?M K(2)Cr(2)O(7) without any significant changes in root growth after 16 days treatment; whereas, chlorophyll content in plants treated with 1 and 10 ?M K(2)Cr(2)O(7) were not so different than the control plant. The levels of lipid peroxidation and protein oxidation increased significantly (p &lt; 0.01) with increasing concentration of chromium. Exposures of N. cochenillifera to lower concentrations of K(2)Cr(2)O(7) (? 10 ?M) induced catalase (CAT) and superoxide dismutase (SOD) significantly (p &lt; 0.001) but higher concentrations of K(2)Cr(2)O(7) (&gt;100 ?M) inhibited the activities of CAT and SOD. Roots accumulated a maximum of 25,263.396 ± 1,722.672 mg Cr Kg(-1) dry weight (DW); while the highest concentration of Cr in N. cochenillifera shoots was 705.714 ± 32.324 mg Cr Kg(-1) DW. N. cochenillifera could be a prospective hyperaccumulator plant of Cr(VI) and a promising candidate for phytoremediation purposes."
1509931,Thompson et al. 2012,Assessment of Cr(VI)-induced cytotoxicity and genotoxicity using high content analysis,"Oral exposure to high concentrations of hexavalent chromium [Cr(VI)] induces intestinal redox changes, villus cytotoxicity, crypt hyperplasia, and intestinal tumors in mice. To assess the effects of Cr(VI) in a cell model relevant to the intestine, undifferentiated (proliferating) and differentiated (confluent) Caco-2 cells were treated with Cr(VI), hydrogen peroxide or rotenone for 2-24 hours. DNA damage was then assessed by nuclear staining intensity of 8-hydroxydeoxyguanosine (8-OHdG) and phosphorylated histone variant H2AX (?-H2AX) measured by high content analysis methods. In undifferentiated Caco-2, all three chemicals increased 8-OHdG and ?-H2AX staining at cytotoxic concentrations, whereas only 8-OHdG was elevated at non-cytotoxic concentrations at 24 hr. Differentiated Caco-2 were more resistant to cytotoxicity and DNA damage than undifferentiated cells, and there were no changes in apoptotic markers p53 or annexin-V. However, Cr(VI) induced a dose-dependent translocation of the unfolded protein response transcription factor ATF6 into the nucleus. Micronucleus (MN) formation was assessed in CHO-K1 and A549 cell lines. Cr(VI) increased MN frequency in CHO-K1 only at highly cytotoxic concentrations. Relative to the positive control Mitomycin-C, Cr(VI) only slightly increased MN frequency in A549 at mildly cytotoxic concentrations. The results demonstrate that Cr(VI) genotoxicity correlates with cytotoxic concentrations, and that H2AX phosphorylation occurs at higher concentrations than oxidative DNA damage in proliferating Caco-2 cells. The findings suggest that in vitro genotoxicity of Cr(VI) is primarily oxidative in nature at low concentrations. Implications for in vivo intestinal toxicity of Cr(VI) will be discussed.","Assessment of Cr(VI)-induced cytotoxicity and genotoxicity using high content analysis Abs: Oral exposure to high concentrations of hexavalent chromium [Cr(VI)] induces intestinal redox changes, villus cytotoxicity, crypt hyperplasia, and intestinal tumors in mice. To assess the effects of Cr(VI) in a cell model relevant to the intestine, undifferentiated (proliferating) and differentiated (confluent) Caco-2 cells were treated with Cr(VI), hydrogen peroxide or rotenone for 2-24 hours. DNA damage was then assessed by nuclear staining intensity of 8-hydroxydeoxyguanosine (8-OHdG) and phosphorylated histone variant H2AX (?-H2AX) measured by high content analysis methods. In undifferentiated Caco-2, all three chemicals increased 8-OHdG and ?-H2AX staining at cytotoxic concentrations, whereas only 8-OHdG was elevated at non-cytotoxic concentrations at 24 hr. Differentiated Caco-2 were more resistant to cytotoxicity and DNA damage than undifferentiated cells, and there were no changes in apoptotic markers p53 or annexin-V. However, Cr(VI) induced a dose-dependent translocation of the unfolded protein response transcription factor ATF6 into the nucleus. Micronucleus (MN) formation was assessed in CHO-K1 and A549 cell lines. Cr(VI) increased MN frequency in CHO-K1 only at highly cytotoxic concentrations. Relative to the positive control Mitomycin-C, Cr(VI) only slightly increased MN frequency in A549 at mildly cytotoxic concentrations. The results demonstrate that Cr(VI) genotoxicity correlates with cytotoxic concentrations, and that H2AX phosphorylation occurs at higher concentrations than oxidative DNA damage in proliferating Caco-2 cells. The findings suggest that in vitro genotoxicity of Cr(VI) is primarily oxidative in nature at low concentrations. Implications for in vivo intestinal toxicity of Cr(VI) will be discussed."
1509930,Chowdhury et al. 2012,Chemical states in XPS and Raman analysis during removal of Cr(VI) from contaminated water by mixed maghemite-magnetite nanoparticles,"Mixed maghemite-magnetite has been used as adsorbent for Cr(VI) removal in this study. Results show that the adsorption capacity is enhanced with an increase in reaction temperature and decrease in free energy change. Thermodynamic study shows that Cr(VI) adsorption on the mixed maghemite and magnetite is endothermic in nature and is dependent on solution pH between 3 and 6. X-ray photoelectron spectroscopy (XPS) results demonstrate the theoretical multiplet peaks for iron and chromium adsorbed iron at the surface of the ?-Fe(2)O(3) and Fe(3)O(4) mixture. Theoretical multiplet analysis shows that during Cr adsorption, the amount of maghemite increases (from 70 to 89%). In magnetite spectra, the relative content of Fe(II) decreases from 8.2 to 3.6% indicating the reduction of magnetite in the mixture particles. In Raman spectroscopy studies, clear peaks of chromium on iron oxide were generated at 826 cm(-1), which could be attributed to chemical interactions between chromium compound and iron oxide. From the results of Raman and XPS studies, electrostatic attraction and oxidation-reduction between chromium and mixed maghemite-magnetite are postulated as mechanisms for the removal of Cr(VI) from aqueous solutions.","Chemical states in XPS and Raman analysis during removal of Cr(VI) from contaminated water by mixed maghemite-magnetite nanoparticles Abs: Mixed maghemite-magnetite has been used as adsorbent for Cr(VI) removal in this study. Results show that the adsorption capacity is enhanced with an increase in reaction temperature and decrease in free energy change. Thermodynamic study shows that Cr(VI) adsorption on the mixed maghemite and magnetite is endothermic in nature and is dependent on solution pH between 3 and 6. X-ray photoelectron spectroscopy (XPS) results demonstrate the theoretical multiplet peaks for iron and chromium adsorbed iron at the surface of the ?-Fe(2)O(3) and Fe(3)O(4) mixture. Theoretical multiplet analysis shows that during Cr adsorption, the amount of maghemite increases (from 70 to 89%). In magnetite spectra, the relative content of Fe(II) decreases from 8.2 to 3.6% indicating the reduction of magnetite in the mixture particles. In Raman spectroscopy studies, clear peaks of chromium on iron oxide were generated at 826 cm(-1), which could be attributed to chemical interactions between chromium compound and iron oxide. From the results of Raman and XPS studies, electrostatic attraction and oxidation-reduction between chromium and mixed maghemite-magnetite are postulated as mechanisms for the removal of Cr(VI) from aqueous solutions."
1509929,Asgari et al. 2012,Kinetic and isotherm of hexavalent chromium adsorption onto nano hydroxyapatite,"<strong>BACKGROUND: </strong>Hexavalent chromium (Cr (VI)) is an important contaminant in surface and groundwater and its removal from contaminated water and wastewater has received interest in recent years. This study aimed to explain the removal process of Cr (VI) from aqueous solution using nano hydroxyapatite (n-HAp) as an adsorbent material.<br /><br /><strong>METHODS: </strong>Cr (VI) removal experiments with the prepared n-HAp were carried out as the batch test in 100 ml flask while agitating on the shaker. The influence of pH (3 toll), contact time (3-60 min), Cr (VI) concentration (1 to 2 mg/L) and adsorbent dosage (0.025 to 1 g/L) were explored. Three isotherms models and eight kinetics models were used to evaluate the experimental data, respectively. For validation of kinetic and isotherm data, correlation coefficient, sum of square errors (SSE) and normalized deviation were used.<br /><br /><strong>RESULTS: </strong>The removal efficiency of Cr (VI) was improved an increase in Cr (VI) and n-HAp concentration. The results best fitted with Langmuir model and the pseudo-second-order rate reaction. Analysis of data with Dubinin Radushkevich isotherm showed that the adsorption of Cr (VI) onto synthetic n-HAp is a chemisorption process.<br /><br /><strong>CONCLUSION: </strong>The n-HAp as an ecofriendly compound is effective adsorbent for the removal of Cr (VI) from aqueous solution. Accordingly, n-HAp is feasible and promise adsorbent for treating polluted Cr (VI) groundwater.","Kinetic and isotherm of hexavalent chromium adsorption onto nano hydroxyapatite Abs: <strong>BACKGROUND: </strong>Hexavalent chromium (Cr (VI)) is an important contaminant in surface and groundwater and its removal from contaminated water and wastewater has received interest in recent years. This study aimed to explain the removal process of Cr (VI) from aqueous solution using nano hydroxyapatite (n-HAp) as an adsorbent material.<br /><br /><strong>METHODS: </strong>Cr (VI) removal experiments with the prepared n-HAp were carried out as the batch test in 100 ml flask while agitating on the shaker. The influence of pH (3 toll), contact time (3-60 min), Cr (VI) concentration (1 to 2 mg/L) and adsorbent dosage (0.025 to 1 g/L) were explored. Three isotherms models and eight kinetics models were used to evaluate the experimental data, respectively. For validation of kinetic and isotherm data, correlation coefficient, sum of square errors (SSE) and normalized deviation were used.<br /><br /><strong>RESULTS: </strong>The removal efficiency of Cr (VI) was improved an increase in Cr (VI) and n-HAp concentration. The results best fitted with Langmuir model and the pseudo-second-order rate reaction. Analysis of data with Dubinin Radushkevich isotherm showed that the adsorption of Cr (VI) onto synthetic n-HAp is a chemisorption process.<br /><br /><strong>CONCLUSION: </strong>The n-HAp as an ecofriendly compound is effective adsorbent for the removal of Cr (VI) from aqueous solution. Accordingly, n-HAp is feasible and promise adsorbent for treating polluted Cr (VI) groundwater."
1509928,Xiao et al. 2012,Hexavalent chromium induces energy metabolism disturbance and p53-dependent cell cycle arrest via reactive oxygen species in L-02 hepatocytes,"Hexavalent chromium [Cr(VI)] has become a non-negligible pollutant in the world. Cr(VI) exposure leads to severe damage to the liver, but the mechanisms involved in Cr(VI)-mediated toxicity in the liver are unclear. The present study aimed to explore whether Cr(VI) induces energy metabolism disturbance and cell cycle arrest in human L-02 hepatocytes. We showed that Cr(VI) inhibited state 3 respiration, respiratory control rate (RCR), and subsequently induced energy metabolism disturbance with decreased ATP production. Interestingly, cell cycle analysis by flow cytometry and protein expression analysis by western blotting revealed that low dose of Cr(VI) (4 uM) exposure induced S phase cell cycle arrest with decreased mediator of replication checkpoint 1 (Mrc1) and cyclin-dependent kinase 2 (CDK2), while higher doses of Cr(VI) (16, 32 uM) exposure resulted in G2/M phase arrest with decreased budding uninhibited by benzimidazoles-related 1 (BubR1) and cell division cycle 25 (CDC25). Mechanism study revealed that Cr(VI) decreased the activities of mitochondrial respiratory chain complex (MRCC) I and II, thus leading to ROS accumulation. Moreover, inhibiting ROS production by antioxidant N-acetyl-L-cysteine (NAC) rescued Cr(VI)-induced ATP depletion and cell cycle arrest. ROS-mediated p53 activation was found to involve in Cr(VI)-induced cell cycle arrest, and p53 inhibitor Pifithrin-? (PFT-?) rescued Cr(VI)-induced reduction of check point proteins Mrc1 and BubR1, thus inhibiting cell cycle arrest. In summary, the present study provides experimental evidence that Cr(VI) leads to energy metabolism disturbance and p53-dependent cell cycle arrest via ROS in L-02 hepatocytes.","Hexavalent chromium induces energy metabolism disturbance and p53-dependent cell cycle arrest via reactive oxygen species in L-02 hepatocytes Abs: Hexavalent chromium [Cr(VI)] has become a non-negligible pollutant in the world. Cr(VI) exposure leads to severe damage to the liver, but the mechanisms involved in Cr(VI)-mediated toxicity in the liver are unclear. The present study aimed to explore whether Cr(VI) induces energy metabolism disturbance and cell cycle arrest in human L-02 hepatocytes. We showed that Cr(VI) inhibited state 3 respiration, respiratory control rate (RCR), and subsequently induced energy metabolism disturbance with decreased ATP production. Interestingly, cell cycle analysis by flow cytometry and protein expression analysis by western blotting revealed that low dose of Cr(VI) (4 uM) exposure induced S phase cell cycle arrest with decreased mediator of replication checkpoint 1 (Mrc1) and cyclin-dependent kinase 2 (CDK2), while higher doses of Cr(VI) (16, 32 uM) exposure resulted in G2/M phase arrest with decreased budding uninhibited by benzimidazoles-related 1 (BubR1) and cell division cycle 25 (CDC25). Mechanism study revealed that Cr(VI) decreased the activities of mitochondrial respiratory chain complex (MRCC) I and II, thus leading to ROS accumulation. Moreover, inhibiting ROS production by antioxidant N-acetyl-L-cysteine (NAC) rescued Cr(VI)-induced ATP depletion and cell cycle arrest. ROS-mediated p53 activation was found to involve in Cr(VI)-induced cell cycle arrest, and p53 inhibitor Pifithrin-? (PFT-?) rescued Cr(VI)-induced reduction of check point proteins Mrc1 and BubR1, thus inhibiting cell cycle arrest. In summary, the present study provides experimental evidence that Cr(VI) leads to energy metabolism disturbance and p53-dependent cell cycle arrest via ROS in L-02 hepatocytes."
1509927,Hou et al. 2012,Combination of electroreduction with biosorption for enhancement for removal of hexavalent chromium,"Hexavalent chromium is one of the most toxic heavy metals in aqueous solutions. It has been well documented that the brown seaweed can be used as a promising biosorbent for the sequestration of this heavy metal from wastewater. However, the uptake of Cr(VI) is reportedly a rather slower process; the sorption equilibrium can only be established after a few days, much slower than a few hours for the trivalent chromium ion. In this study, we developed a novel technology of electrochemically assisted biosorption (ECAB) system for the enhancement of the treatment efficiency. It was found through our study that the removal efficiencies of Cr(VI) and total chromium were greatly enhanced by 48.1% and 51.3%, respectively, with the application of -1.0 V in the ECAB system. The conversion of Cr(III) due to the electroreduction of Cr(VI) and the higher pH due to the cathodic H(2) evolution created a favorable condition for the uptake of chromium onto the modified seaweed (MSW). The reduction and adsorption of Cr(VI) by MSW was proved to play a minor role in the removal. Both direct electroreduction and indirect electroreduction by atomic H* contributed to the reduction of Cr(VI).","Combination of electroreduction with biosorption for enhancement for removal of hexavalent chromium Abs: Hexavalent chromium is one of the most toxic heavy metals in aqueous solutions. It has been well documented that the brown seaweed can be used as a promising biosorbent for the sequestration of this heavy metal from wastewater. However, the uptake of Cr(VI) is reportedly a rather slower process; the sorption equilibrium can only be established after a few days, much slower than a few hours for the trivalent chromium ion. In this study, we developed a novel technology of electrochemically assisted biosorption (ECAB) system for the enhancement of the treatment efficiency. It was found through our study that the removal efficiencies of Cr(VI) and total chromium were greatly enhanced by 48.1% and 51.3%, respectively, with the application of -1.0 V in the ECAB system. The conversion of Cr(III) due to the electroreduction of Cr(VI) and the higher pH due to the cathodic H(2) evolution created a favorable condition for the uptake of chromium onto the modified seaweed (MSW). The reduction and adsorption of Cr(VI) by MSW was proved to play a minor role in the removal. Both direct electroreduction and indirect electroreduction by atomic H* contributed to the reduction of Cr(VI)."
1509926,Yuan et al. 2012,Cr(VI) induces the decrease of ATP level and the increase of apoptosis rate mediated by ROS or VDAC1 in L-02 hepatocytes,"The present study explored the ability of the voltage-dependent anion channel 1 (VDAC1) mRNA and ROS levels to modulate the effects of hexavalent chromium Cr(VI) on the adenosine triphosphate (ATP) level and the rate of apoptotic cell death. Cultured L-02 cells were pretreated with 20mM N-acetyl-cysteine (NAC) for 24h or transiently transfected with small interfering RNAs targeting VDAC1 (siVDAC1) for 48h; cells that were not pretreated were used as the control. The cells were subsequently treated with 0, 2, 8, or 32?M Cr(VI) for 24h. Then, levels of VDAC1 mRNA, ROS, and ATP and the apoptosis rate were measured by reverse-transcription quantitative PCR, fluorometry, a bioluminescence assay, and flow cytometry, respectively. The results showed that Cr(VI) at 32?M led to increase in the ROS level, VDAC1 mRNA expression, and the apoptosis rate and a decrease in the ATP level; pretreatment with NAC led to the down-regulation in the levels of ROS, VDAC1 mRNA and apoptosis and the significant up-regulation in the ATP levels. Interestingly, after the pretreatment with siVDAC1 to inhibit VDAC1 mRNA expression, the increased apoptosis rates and decreased ATP levels were reversed as well. These results suggested that changes in the ROS or VDAC1 mRNA levels were associated with changes in the ATP level and apoptosis rate. Furthermore, correlation analysis confirmed the association between both the ROS and VDAC1 levels and both the ATP level and the apoptosis rate. In conclusion, Cr(VI) induced ROS- and VDAC1-mediated decreases in ATP levels and increases in the apoptosis rate.","Cr(VI) induces the decrease of ATP level and the increase of apoptosis rate mediated by ROS or VDAC1 in L-02 hepatocytes Abs: The present study explored the ability of the voltage-dependent anion channel 1 (VDAC1) mRNA and ROS levels to modulate the effects of hexavalent chromium Cr(VI) on the adenosine triphosphate (ATP) level and the rate of apoptotic cell death. Cultured L-02 cells were pretreated with 20mM N-acetyl-cysteine (NAC) for 24h or transiently transfected with small interfering RNAs targeting VDAC1 (siVDAC1) for 48h; cells that were not pretreated were used as the control. The cells were subsequently treated with 0, 2, 8, or 32?M Cr(VI) for 24h. Then, levels of VDAC1 mRNA, ROS, and ATP and the apoptosis rate were measured by reverse-transcription quantitative PCR, fluorometry, a bioluminescence assay, and flow cytometry, respectively. The results showed that Cr(VI) at 32?M led to increase in the ROS level, VDAC1 mRNA expression, and the apoptosis rate and a decrease in the ATP level; pretreatment with NAC led to the down-regulation in the levels of ROS, VDAC1 mRNA and apoptosis and the significant up-regulation in the ATP levels. Interestingly, after the pretreatment with siVDAC1 to inhibit VDAC1 mRNA expression, the increased apoptosis rates and decreased ATP levels were reversed as well. These results suggested that changes in the ROS or VDAC1 mRNA levels were associated with changes in the ATP level and apoptosis rate. Furthermore, correlation analysis confirmed the association between both the ROS and VDAC1 levels and both the ATP level and the apoptosis rate. In conclusion, Cr(VI) induced ROS- and VDAC1-mediated decreases in ATP levels and increases in the apoptosis rate."
1509925,Mishra and  Mohanty ,"Acute spill-mimicking exposure effect of hexavalent chromium on the pituitary-ovarian axis of a teleost, Channa punctatus (Bloch)","Acute exposure to hexavalent chromium (as 10, 20, and 40 mg/L potassium dichromate for 96 h) adversely affected the pituitary-ovarian axis of a teleost Channa punctatus. The toxic impact of metal exposure on fish ovary was revealed in the form of increased percentage of atretic follicles, significantly in 20 mg/L and 40 mg/L exposure groups. The follicular atresia mostly occurred in vitellogenic (stage II and stage III) oocytes. Reduction of serum level of 17?-estradiol was also significant in 20 mg/L and 40 mg/L exposure groups. The increase of LH-immunointensity of pituitary gonadotrophs (LH?-immunoreactive cells) and their hypertrophy was evident, significantly in fish of 40 mg/L exposed group. Thus, the present acute metal spill-mimicking laboratory study clearly demonstrated that short-term exposures to high doses of hexavalent chromium may disrupt reproduction of the fish and affect their population. © 2012 Wiley Periodicals, Inc. Environ Toxicol 2012.","Acute spill-mimicking exposure effect of hexavalent chromium on the pituitary-ovarian axis of a teleost, Channa punctatus (Bloch) Abs: Acute exposure to hexavalent chromium (as 10, 20, and 40 mg/L potassium dichromate for 96 h) adversely affected the pituitary-ovarian axis of a teleost Channa punctatus. The toxic impact of metal exposure on fish ovary was revealed in the form of increased percentage of atretic follicles, significantly in 20 mg/L and 40 mg/L exposure groups. The follicular atresia mostly occurred in vitellogenic (stage II and stage III) oocytes. Reduction of serum level of 17?-estradiol was also significant in 20 mg/L and 40 mg/L exposure groups. The increase of LH-immunointensity of pituitary gonadotrophs (LH?-immunoreactive cells) and their hypertrophy was evident, significantly in fish of 40 mg/L exposed group. Thus, the present acute metal spill-mimicking laboratory study clearly demonstrated that short-term exposures to high doses of hexavalent chromium may disrupt reproduction of the fish and affect their population. © 2012 Wiley Periodicals, Inc. Environ Toxicol 2012."
1509924,Larraza et al. 2012,"Hybrid materials: Magnetite-Polyethylenimine-Montmorillonite, as magnetic adsorbents for Cr(VI) water treatment","Hybrid materials formed by the combination of a sodium rich Montmorillonite (MMT), with magnetite nanoparticles (40 nm, Fe(3)O(4) NPs) coated with Polyethylenimine polymer (PEI 800 g/mol or PEI 25000 g/mol) were prepared. The intercalation of the magnetite nanoparticles coated with PEI among MMT platelets was achieved by cationic exchange. The resulting materials presented a high degree of exfoliation of the MMT sheets and a good dispersion of Fe(3)O(4) NPs on both the surface and among the layers of MMT. The presence of amine groups in the PEI structure not only aids the exfoliation of the MMT layers, but also gives to the hybrid material the necessary functionality to interact with heavy metals. These hybrid materials were used as magnetic sorbent for the removal of hexavalent chromium from water. The effect that pH, Cr(VI) concentration, and adsorbent material composition have on the Cr(VI) removal efficiency was studied. A complete characterization of the materials was performed. The hybrid materials showed a slight dependence of the removal efficiency with the pH in a wide range (1-9). A maximum amount of adsorption capacity of 8.8 mg/g was determined by the Langmuir isotherm. Results show that these hybrid materials can be considered as potential magnetic adsorbent for the Cr(VI) removal from water in a wide range of pH.","Hybrid materials: Magnetite-Polyethylenimine-Montmorillonite, as magnetic adsorbents for Cr(VI) water treatment Abs: Hybrid materials formed by the combination of a sodium rich Montmorillonite (MMT), with magnetite nanoparticles (40 nm, Fe(3)O(4) NPs) coated with Polyethylenimine polymer (PEI 800 g/mol or PEI 25000 g/mol) were prepared. The intercalation of the magnetite nanoparticles coated with PEI among MMT platelets was achieved by cationic exchange. The resulting materials presented a high degree of exfoliation of the MMT sheets and a good dispersion of Fe(3)O(4) NPs on both the surface and among the layers of MMT. The presence of amine groups in the PEI structure not only aids the exfoliation of the MMT layers, but also gives to the hybrid material the necessary functionality to interact with heavy metals. These hybrid materials were used as magnetic sorbent for the removal of hexavalent chromium from water. The effect that pH, Cr(VI) concentration, and adsorbent material composition have on the Cr(VI) removal efficiency was studied. A complete characterization of the materials was performed. The hybrid materials showed a slight dependence of the removal efficiency with the pH in a wide range (1-9). A maximum amount of adsorption capacity of 8.8 mg/g was determined by the Langmuir isotherm. Results show that these hybrid materials can be considered as potential magnetic adsorbent for the Cr(VI) removal from water in a wide range of pH."
1509923,Bonamonte et al. 2012,Nummular eczema and contact allergy: a retrospective study,"<strong>BACKGROUND: </strong>Etiopathogenesis of nummular eczema is obscure; many causative factors have been proposed. Only a few studies investigated the relevance of contact allergy.<br /><br /><strong>OBJECTIVE: </strong>This retrospective study aimed to investigate the role of contact allergy in the underlying mechanism of nummular eczema.<br /><br /><strong>METHODS: </strong>From the 29,323 consecutive patients, we patch-tested for eczematous dermatitis of various type, 1022 (3.5%) with nummular eczema were enrolled. Data were collected for each patient, including age, sex, occupation, symptoms onset and duration, onset and spread sites, and clinical evidence or history of atopy. Histological analyses of acute phase lesions were carried out in some patients.<br /><br /><strong>RESULTS: </strong>Peak incidence of age at disease onset was found in the third decade of life. Predominant sites of lesions were upper (75.8%) and lower (64.5%) limbs, followed by trunk, dorsum of the hands, and face and neck. Three hundred thirty-two (32.5%) of 1022 patients showed positive reactions to 1 or more allergens. Highest sensitization rates were found with nickel sulfate (10.2%), potassium dichromate (7.3%), and cobalt chloride (6.1%). Histopathology showed less pronounced spongiosis in atopic subjects and the elderly.<br /><br /><strong>CONCLUSIONS: </strong>Because this study demonstrates that contact allergy is common with nummular eczema, patch testing is strongly advisable in every patient with persistent nummular dermatitis.","Nummular eczema and contact allergy: a retrospective study Abs: <strong>BACKGROUND: </strong>Etiopathogenesis of nummular eczema is obscure; many causative factors have been proposed. Only a few studies investigated the relevance of contact allergy.<br /><br /><strong>OBJECTIVE: </strong>This retrospective study aimed to investigate the role of contact allergy in the underlying mechanism of nummular eczema.<br /><br /><strong>METHODS: </strong>From the 29,323 consecutive patients, we patch-tested for eczematous dermatitis of various type, 1022 (3.5%) with nummular eczema were enrolled. Data were collected for each patient, including age, sex, occupation, symptoms onset and duration, onset and spread sites, and clinical evidence or history of atopy. Histological analyses of acute phase lesions were carried out in some patients.<br /><br /><strong>RESULTS: </strong>Peak incidence of age at disease onset was found in the third decade of life. Predominant sites of lesions were upper (75.8%) and lower (64.5%) limbs, followed by trunk, dorsum of the hands, and face and neck. Three hundred thirty-two (32.5%) of 1022 patients showed positive reactions to 1 or more allergens. Highest sensitization rates were found with nickel sulfate (10.2%), potassium dichromate (7.3%), and cobalt chloride (6.1%). Histopathology showed less pronounced spongiosis in atopic subjects and the elderly.<br /><br /><strong>CONCLUSIONS: </strong>Because this study demonstrates that contact allergy is common with nummular eczema, patch testing is strongly advisable in every patient with persistent nummular dermatitis."
1509922,Liu et al. 2012,"Removal of hexavalent chromium from wastewater by Fe0-nanoparticles-chitosan composite beads: characterization, kinetics and thermodynamics","Fe0-nanoparticles-chitosan composite beads (CS-NZVI beads) were prepared and used to remove hexavalent chromium (Cr (VI)) from wastewater. Characterization with a scanning electron microscopy (SEM) demonstrated that with the increase of the concentration of CS from 5.0 to 20.0 g/L and NaOH from 0.5 to 2.0 mol/L, the average aperture size of the CS-NZVI beads decreased from 26.8 to 10.6 ?m and 42.6 to 0.8 ?m, respectively. Batch experiments revealed that the removal of Cr (VI) using CS-NZVI beads was consistent with pseudo first-order reaction kinetics. The rate constant increased with increasing NZVI dosage but decreased with the increase in pH values. The Freundlich isotherm described the adsorption process better, suggesting that the CS-NZVI beads were heterogeneous in the surface properties. At equilibrium qmax was 35.97 mg/g. The thermodynamics study suggested that Cr (VI) removal by CS-NZVI beads was an endothermic and spontaneous process, reflecting good affinity of the sorbent for Cr (VI) ions and increasing randomness at the solid-solution interface during the adsorption process. This result will be very useful to understand the effects of NZVI on heavy metal Cr (VI) removal from wastewater in the successful application.","Removal of hexavalent chromium from wastewater by Fe0-nanoparticles-chitosan composite beads: characterization, kinetics and thermodynamics Abs: Fe0-nanoparticles-chitosan composite beads (CS-NZVI beads) were prepared and used to remove hexavalent chromium (Cr (VI)) from wastewater. Characterization with a scanning electron microscopy (SEM) demonstrated that with the increase of the concentration of CS from 5.0 to 20.0 g/L and NaOH from 0.5 to 2.0 mol/L, the average aperture size of the CS-NZVI beads decreased from 26.8 to 10.6 ?m and 42.6 to 0.8 ?m, respectively. Batch experiments revealed that the removal of Cr (VI) using CS-NZVI beads was consistent with pseudo first-order reaction kinetics. The rate constant increased with increasing NZVI dosage but decreased with the increase in pH values. The Freundlich isotherm described the adsorption process better, suggesting that the CS-NZVI beads were heterogeneous in the surface properties. At equilibrium qmax was 35.97 mg/g. The thermodynamics study suggested that Cr (VI) removal by CS-NZVI beads was an endothermic and spontaneous process, reflecting good affinity of the sorbent for Cr (VI) ions and increasing randomness at the solid-solution interface during the adsorption process. This result will be very useful to understand the effects of NZVI on heavy metal Cr (VI) removal from wastewater in the successful application."
1509921,Adams and  Marshall-Battle 2012,Shoe contact dermatitis: a case report of an acute severe reaction to potassium dichromate,"<strong>BACKGROUND: </strong>Shoe contact dermatitis is common in both the pediatric and the adult populations. Severity of the reaction can vary greatly by patient.<br /><br /><strong>OBJECTIVES: </strong>Health Care Professionals of all types should be familiar with shoe related dermatitis and aware of potential antigens that can precipitate a shoe contact dermatitis.<br /><br /><strong>METHODS: </strong>This article reviews one of the most common patch test, the T.R.U.E., Thin-layer Rapid Use of Epicutaneous test, for determination of the causative agent in a case of shoe contact dermatitis.<br /><br /><strong>RESULTS: </strong>This article outlines a severe reaction to dichromate in a shoe and the clinical treatment required for a severe, limb threatening, reaction which included in-patient and out-patient management of the condition.<br /><br /><strong>CONCLUSION: </strong>The clinician will become familiar with several common antigens responsible for contact dermatitis, including rubber, dichromate, thimerosal and other medications and other non-shoe products that can contain these agents.","Shoe contact dermatitis: a case report of an acute severe reaction to potassium dichromate Abs: <strong>BACKGROUND: </strong>Shoe contact dermatitis is common in both the pediatric and the adult populations. Severity of the reaction can vary greatly by patient.<br /><br /><strong>OBJECTIVES: </strong>Health Care Professionals of all types should be familiar with shoe related dermatitis and aware of potential antigens that can precipitate a shoe contact dermatitis.<br /><br /><strong>METHODS: </strong>This article reviews one of the most common patch test, the T.R.U.E., Thin-layer Rapid Use of Epicutaneous test, for determination of the causative agent in a case of shoe contact dermatitis.<br /><br /><strong>RESULTS: </strong>This article outlines a severe reaction to dichromate in a shoe and the clinical treatment required for a severe, limb threatening, reaction which included in-patient and out-patient management of the condition.<br /><br /><strong>CONCLUSION: </strong>The clinician will become familiar with several common antigens responsible for contact dermatitis, including rubber, dichromate, thimerosal and other medications and other non-shoe products that can contain these agents."
1509920,Duarte et al. 2012,"Hexavalent chromium reduction, uptake and oxidative biomarkers in Halimione portulacoides","The in situ reduction of Cr (VI) to its less toxic form Cr (III) may be a useful detoxification mechanism for phytoremediation. Using a hydroponics mesocosmos approach, we evaluated the ability of Halimione portulacoides to reduce and uptake Cr (VI) and its anti-oxidative feedback and biomarkers. It was found that this specie can, not only reduce large amounts of Cr (VI) in the external medium, but also withdrawn and accumulate this element in its roots and aboveground organs. Both these mechanisms were found to be dose dependent. Jointly with this phytoremediative potential the oxidative feedback was also assessed. Chromium uptake had its major implications on the chlorophyll content and flavonoid content, with potential consequences in the photosynthetic and photo-protective mechanisms. Although the high Cr root accumulation in H. portulacoides, there were no inactivation of the enzymatic defenses, allowing a continuous defense against reactive oxygen species. In fact, GPX and specially SOD revealed to be an excellent dose-related biomarker of Cr induced stress. All these aspects make this specie suitable for Cr (VI) phytoremediation processes, either by phytoextraction or by reduction of Cr (VI) to Cr (III) and also for monitoring programs using SOD and GPX as biomarkers of Cr environmental contamination.","Hexavalent chromium reduction, uptake and oxidative biomarkers in Halimione portulacoides Abs: The in situ reduction of Cr (VI) to its less toxic form Cr (III) may be a useful detoxification mechanism for phytoremediation. Using a hydroponics mesocosmos approach, we evaluated the ability of Halimione portulacoides to reduce and uptake Cr (VI) and its anti-oxidative feedback and biomarkers. It was found that this specie can, not only reduce large amounts of Cr (VI) in the external medium, but also withdrawn and accumulate this element in its roots and aboveground organs. Both these mechanisms were found to be dose dependent. Jointly with this phytoremediative potential the oxidative feedback was also assessed. Chromium uptake had its major implications on the chlorophyll content and flavonoid content, with potential consequences in the photosynthetic and photo-protective mechanisms. Although the high Cr root accumulation in H. portulacoides, there were no inactivation of the enzymatic defenses, allowing a continuous defense against reactive oxygen species. In fact, GPX and specially SOD revealed to be an excellent dose-related biomarker of Cr induced stress. All these aspects make this specie suitable for Cr (VI) phytoremediation processes, either by phytoextraction or by reduction of Cr (VI) to Cr (III) and also for monitoring programs using SOD and GPX as biomarkers of Cr environmental contamination."
1509919,Magro et al. 2012,Chromium (VI) biosorption and removal of chemical oxygen demand by Spirulina platensis from wastewater-supplemented culture medium,"The inappropriate discharge of wastewater containing high concentrations of toxic metals is a serious threat to the environment. Given that the microalga Spirulina platensis has demonstrated a capacity for chromium VI (Cr (VI) biosorption, we assessed the ideal concentration of chromium-containing wastewater required for maximum removal of Cr (VI) and chemical oxygen demand (COD) from the environment by using this microalga. The Paracas and Leb-52 strains of S. platensis, with initial wastewater concentrations of 0%, 12.5%, 25%, and 50%, were cultured in Zarrouk medium diluted to 50% under controlled air, temperature, and lighting conditions. The cultures were maintained for 28 days, and pH, biomass growth, COD, and Cr (VI) were assessed. The wastewater concentration influenced microalgal growth, especially at high concentrations. Removal of 82.19% COD and 60.92% Cr (VI) was obtained, but the COD removal was greater than the Cr (VI) removal in both strains of S. platensis.","Chromium (VI) biosorption and removal of chemical oxygen demand by Spirulina platensis from wastewater-supplemented culture medium Abs: The inappropriate discharge of wastewater containing high concentrations of toxic metals is a serious threat to the environment. Given that the microalga Spirulina platensis has demonstrated a capacity for chromium VI (Cr (VI) biosorption, we assessed the ideal concentration of chromium-containing wastewater required for maximum removal of Cr (VI) and chemical oxygen demand (COD) from the environment by using this microalga. The Paracas and Leb-52 strains of S. platensis, with initial wastewater concentrations of 0%, 12.5%, 25%, and 50%, were cultured in Zarrouk medium diluted to 50% under controlled air, temperature, and lighting conditions. The cultures were maintained for 28 days, and pH, biomass growth, COD, and Cr (VI) were assessed. The wastewater concentration influenced microalgal growth, especially at high concentrations. Removal of 82.19% COD and 60.92% Cr (VI) was obtained, but the COD removal was greater than the Cr (VI) removal in both strains of S. platensis."
1509918,Dai et al. 2012,Adsorption of Cr(VI) and speciation of Cr(VI) and Cr(III) in aqueous solutions using chemically modified chitosan,"A new type of grafting chitosan (CTS) was synthesized using 2-hydroxyethyl-trimethyl ammonium chloride (HGCTS). The adsorption of Cr(VI) on HGCTS was studied. The effect factors on adsorption and the adsorption mechanism were considered. The results indicated that the HGCTS could concentrate and separate Cr(VI) at pH 4.0; the adsorption equilibrium time was 80 min; the maximum adsorption capacity was 205 mg/g. The adsorption isotherm and kinetics were investigated, equilibrium data agreed very well with the Langmuir model and the pseudo second-order model could describe the adsorption process better than the pseudo first-order model. A novel method for speciation of Cr(VI) and Cr(III) in environmental water samples has been developed using HGCTS as adsorbent and FAAS as determination means. The detection limit of this method was 20 ng/L, the relatively standard deviation was 1.2% and the recovery was 99%~105%.","Adsorption of Cr(VI) and speciation of Cr(VI) and Cr(III) in aqueous solutions using chemically modified chitosan Abs: A new type of grafting chitosan (CTS) was synthesized using 2-hydroxyethyl-trimethyl ammonium chloride (HGCTS). The adsorption of Cr(VI) on HGCTS was studied. The effect factors on adsorption and the adsorption mechanism were considered. The results indicated that the HGCTS could concentrate and separate Cr(VI) at pH 4.0; the adsorption equilibrium time was 80 min; the maximum adsorption capacity was 205 mg/g. The adsorption isotherm and kinetics were investigated, equilibrium data agreed very well with the Langmuir model and the pseudo second-order model could describe the adsorption process better than the pseudo first-order model. A novel method for speciation of Cr(VI) and Cr(III) in environmental water samples has been developed using HGCTS as adsorbent and FAAS as determination means. The detection limit of this method was 20 ng/L, the relatively standard deviation was 1.2% and the recovery was 99%~105%."
1509917,Choppala et al. 2012,The influence of biochar and black carbon on reduction and bioavailability of chromate in soils,"The widespread use of chromium (Cr) has a deleterious impact on the environment. A number of pathways, both biotic and abiotic in character, determine the fate and speciation of Cr in soils. Chromium exists in two predominant species in the environment: trivalent [(Cr(III)] and hexavalent [Cr(VI)]. Of these two forms, Cr(III) is nontoxic and is strongly bound to soil particles, whereas Cr(VI) is more toxic and soluble and readily leaches into groundwater. The toxicity of Cr(VI) can be mitigated by reducing it to Cr(III) species. The objective of this study was to examine the effect of organic carbon sources on the reduction, microbial respiration, and phytoavailability of Cr(VI) in soils. Organic carbon sources, such as black carbon (BC) and biochar, were tested for their potential in reducing Cr(VI) in acidic and alkaline contaminated soils. An alkaline soil was selected to monitor the phytotoxicity of Cr(VI) in sunflower plant. Our results showed that using BC resulted in greater reduction of Cr(VI) in soils compared with biochar. This is attributed to the differences in dissolved organic carbon and functional groups that provide electrons for the reduction of Cr(VI). When increasing levels of Cr were added to soils, both microbial respiration and plant growth decreased. The application of BC was more effective than biochar in increasing the microbial population and in mitigating the phytotoxicity of Cr(VI). The net benefit of BC emerged as an increase in plant biomass and a decrease in Cr concentration in plant tissue. Consequently, it was concluded that BC is a potential reducing amendment in mitigating Cr(VI) toxicity in soil and plants.","The influence of biochar and black carbon on reduction and bioavailability of chromate in soils Abs: The widespread use of chromium (Cr) has a deleterious impact on the environment. A number of pathways, both biotic and abiotic in character, determine the fate and speciation of Cr in soils. Chromium exists in two predominant species in the environment: trivalent [(Cr(III)] and hexavalent [Cr(VI)]. Of these two forms, Cr(III) is nontoxic and is strongly bound to soil particles, whereas Cr(VI) is more toxic and soluble and readily leaches into groundwater. The toxicity of Cr(VI) can be mitigated by reducing it to Cr(III) species. The objective of this study was to examine the effect of organic carbon sources on the reduction, microbial respiration, and phytoavailability of Cr(VI) in soils. Organic carbon sources, such as black carbon (BC) and biochar, were tested for their potential in reducing Cr(VI) in acidic and alkaline contaminated soils. An alkaline soil was selected to monitor the phytotoxicity of Cr(VI) in sunflower plant. Our results showed that using BC resulted in greater reduction of Cr(VI) in soils compared with biochar. This is attributed to the differences in dissolved organic carbon and functional groups that provide electrons for the reduction of Cr(VI). When increasing levels of Cr were added to soils, both microbial respiration and plant growth decreased. The application of BC was more effective than biochar in increasing the microbial population and in mitigating the phytotoxicity of Cr(VI). The net benefit of BC emerged as an increase in plant biomass and a decrease in Cr concentration in plant tissue. Consequently, it was concluded that BC is a potential reducing amendment in mitigating Cr(VI) toxicity in soil and plants."
1509916,Mishra et al. 2012,Reduction of Chromium-VI by Chromium Resistant Lactobacilli: A Prospective Bacterium for Bioremediation,"Chromium is a toxic heavy metal, which primarily exists in two inorganic forms, Cr (VI) and Cr (III). Highly soluble hexavalent chromium is carcinogenic due to its oxidizing nature. It is well established that the intestinal bacteria including Lactobacilli have regulatory effect on intestinal homeostasis and a breakdown in the relationship between intestinal cells and bacteria results in the manifestation of gastrointestinal (GI) disorders. In this study Cr (VI) resistance was developed in Lactobacillus strains and the reduction of Cr (VI) was evaluated. All resistant strains showed similarities with their respective normal strains and did not acquire resistance to various antibiotics. A complete bacterial reduction of 32ppm Cr (VI) was observed within 6 to 8 hours. The presence of chromate reducing enzyme have also been established following the partial purification (2 to 5 fold) and characterization of chromate reductase in Lactobacillus strains. The chromate reductase of our strains showed optimum activity at pH 6.0 and 30°C. To our knowledge; these strains are fast in Cr (VI) reduction than any other known bacteria. The results suggest that chromate- resistant Lactobacillus strains would be useful for chromium detoxification from GI-tract as well as for bioremediation of hexavalent chromium from contaminated environment.","Reduction of Chromium-VI by Chromium Resistant Lactobacilli: A Prospective Bacterium for Bioremediation Abs: Chromium is a toxic heavy metal, which primarily exists in two inorganic forms, Cr (VI) and Cr (III). Highly soluble hexavalent chromium is carcinogenic due to its oxidizing nature. It is well established that the intestinal bacteria including Lactobacilli have regulatory effect on intestinal homeostasis and a breakdown in the relationship between intestinal cells and bacteria results in the manifestation of gastrointestinal (GI) disorders. In this study Cr (VI) resistance was developed in Lactobacillus strains and the reduction of Cr (VI) was evaluated. All resistant strains showed similarities with their respective normal strains and did not acquire resistance to various antibiotics. A complete bacterial reduction of 32ppm Cr (VI) was observed within 6 to 8 hours. The presence of chromate reducing enzyme have also been established following the partial purification (2 to 5 fold) and characterization of chromate reductase in Lactobacillus strains. The chromate reductase of our strains showed optimum activity at pH 6.0 and 30°C. To our knowledge; these strains are fast in Cr (VI) reduction than any other known bacteria. The results suggest that chromate- resistant Lactobacillus strains would be useful for chromium detoxification from GI-tract as well as for bioremediation of hexavalent chromium from contaminated environment."
1509915,Javaid and  Sultan ,Plant growth promotion traits and Cr (VI) reduction potentials of Cr (VI) resistant Streptomyces strains,"The most toxic form of chromium [Cr (VI)] can be converted to less toxic Cr (III) by reduction with the help of microbes. A total of 6 Streptomyces strains (S. matansis BG5, Streptomyces sp. RSF17, S. vinaceus CRF2, Streptomyces sp. CRF14, S. pulcher CRF17, S. griseoincarnatus SCF18) which were previously isolated from saline farmlands of Punjab, Pakistan, were used in this work. These strains showed varying levels of resistance to Cr (VI) from 800 ?g ml(-1) to 1000 mg l(-1) . Their plant growth promoting and Cr (VI) reduction potentials were assessed. Two strains showed positive phosphate solubilization activity. All the strains had ability to produce indole acetic acid (IAA) except one strain (CRF17). The maximum production of IAA was observed by strain BG5 that was 16 mg l(-1) in the presence of 50 mg l(-1) of Cr (VI). All the strains were able to produce ammonia both in the absence and presence of Cr (VI). The highest Cr (VI) reduction in majority of the strains was observed at 28 °C and pH 9. The complete reduction of 150 mg l(-1) of Cr (VI) occurred after 168 hrs. The chromium (VI) concentration of 200 mg l(-1) could be reduced above 90% by most of these strains. The presence of other metals also enhanced Cr (VI) reduction by most of the strains. The results indicate the potential capacity of Streptomyces strains as tool for plant growth promotion and Cr (VI) bioremediation and also is the first report about plant growth promoting traits of Cr (VI) resistant Streptomyces strains. (© 2011 WILEY-VCH Verlag GmbH &amp; Co. KGaA, Weinheim).","Plant growth promotion traits and Cr (VI) reduction potentials of Cr (VI) resistant Streptomyces strains Abs: The most toxic form of chromium [Cr (VI)] can be converted to less toxic Cr (III) by reduction with the help of microbes. A total of 6 Streptomyces strains (S. matansis BG5, Streptomyces sp. RSF17, S. vinaceus CRF2, Streptomyces sp. CRF14, S. pulcher CRF17, S. griseoincarnatus SCF18) which were previously isolated from saline farmlands of Punjab, Pakistan, were used in this work. These strains showed varying levels of resistance to Cr (VI) from 800 ?g ml(-1) to 1000 mg l(-1) . Their plant growth promoting and Cr (VI) reduction potentials were assessed. Two strains showed positive phosphate solubilization activity. All the strains had ability to produce indole acetic acid (IAA) except one strain (CRF17). The maximum production of IAA was observed by strain BG5 that was 16 mg l(-1) in the presence of 50 mg l(-1) of Cr (VI). All the strains were able to produce ammonia both in the absence and presence of Cr (VI). The highest Cr (VI) reduction in majority of the strains was observed at 28 °C and pH 9. The complete reduction of 150 mg l(-1) of Cr (VI) occurred after 168 hrs. The chromium (VI) concentration of 200 mg l(-1) could be reduced above 90% by most of these strains. The presence of other metals also enhanced Cr (VI) reduction by most of the strains. The results indicate the potential capacity of Streptomyces strains as tool for plant growth promotion and Cr (VI) bioremediation and also is the first report about plant growth promoting traits of Cr (VI) resistant Streptomyces strains. (© 2011 WILEY-VCH Verlag GmbH &amp; Co. KGaA, Weinheim)."
1509914,Asakai and  Hioki 2012,Evaluation of the stability of iron(II) solutions by precise coulometric titration with electrogenerated cerium(IV),"An iron(II) solution is often used as a reducing agent in titrimetry and standardized with cerium(IV) or potassium dichromate. Such an iron(II) standard solution is needed for not only titrimetric analyses, but also instrumental ones. Iron(II) is unstable even in a highly acidic solution, mainly due to air-oxidation; therefore, its standardization is required before use. In the present study, the concentration of an iron(II) solution was accurately determined by coulometric titration with electrogenerated cerium(IV), and also by gravimetric titration with a standard potassium dichromate; new useful information concerning the stability of iron(II) solutions in aqueous sulfuric acid was obtained. The current efficiency of the coulometric titration with electrogenerated cerium(IV) was not very high; however, it was found that the titration efficiency was sufficient to assay an iron(II) solution.","Evaluation of the stability of iron(II) solutions by precise coulometric titration with electrogenerated cerium(IV) Abs: An iron(II) solution is often used as a reducing agent in titrimetry and standardized with cerium(IV) or potassium dichromate. Such an iron(II) standard solution is needed for not only titrimetric analyses, but also instrumental ones. Iron(II) is unstable even in a highly acidic solution, mainly due to air-oxidation; therefore, its standardization is required before use. In the present study, the concentration of an iron(II) solution was accurately determined by coulometric titration with electrogenerated cerium(IV), and also by gravimetric titration with a standard potassium dichromate; new useful information concerning the stability of iron(II) solutions in aqueous sulfuric acid was obtained. The current efficiency of the coulometric titration with electrogenerated cerium(IV) was not very high; however, it was found that the titration efficiency was sufficient to assay an iron(II) solution."
1509913,Machovcova 2012,The frequency of contact allergy in children and adolescents in the Czech Republic,"The objective of our study was to determine the prevalence of contact hypersensitivity in asymptomatic Czech schoolchildren. We recruited 236 Prague asymptomatic schoolchildren for epicutaneous tests. The children were tested with European baseline series (25 allergens). A total of 218 children (114 boys and 104 girls) completed the study. Of these, 67 (30.7%) children had one or more positive reactions to tested allergens. Nickel, neomycin and potassium dichromate were the most prevalent allergens detected in our study. Our findings may support the notion that allergic contact sensitization in children is not so rare and children, especially those with chronic dermatitis, should be patch tested regularly.","The frequency of contact allergy in children and adolescents in the Czech Republic Abs: The objective of our study was to determine the prevalence of contact hypersensitivity in asymptomatic Czech schoolchildren. We recruited 236 Prague asymptomatic schoolchildren for epicutaneous tests. The children were tested with European baseline series (25 allergens). A total of 218 children (114 boys and 104 girls) completed the study. Of these, 67 (30.7%) children had one or more positive reactions to tested allergens. Nickel, neomycin and potassium dichromate were the most prevalent allergens detected in our study. Our findings may support the notion that allergic contact sensitization in children is not so rare and children, especially those with chronic dermatitis, should be patch tested regularly."
1509912,Hassan et al. 2012,Detection of Cr6+ by the sulfur oxidizing bacteria biosensor: effect of different physical factors,"A biosensor based on sulfur-oxidizing bacteria (SOB) for detection of toxic chemicals in water was developed. SOB are acidophilic microorganisms that get their energy through the oxidation of reduced sulfur compounds in the presence of oxygen to produce sulfuric acid. The reaction results in an increase in electrical conductivity (EC) and a decrease in pH. The bioassay is based on the inhibition of SOB in the presence of toxic chemicals by measuring changes in EC and pH. The effect of different physical factors such as HRT, inorganic sulfur (S°) particle size, and temperature on detection of Cr(6+) was studied. The detection of Cr(6+) (50 ppb) was improved by decreasing the hydraulic retention time (HRT) from 30 to 10 min and increasing S° particle size from 1 to 4.75 mm. Detection time was shorter at 30 °C compared to 45 °C and the SOB were active over a wide range of temperatures with a maximum temperature for growth at 45 °C. This novel biosensor is simple, highly sensitive to low Cr(6+) concentrations (50 ppb), and also minimizes detection time. The present findings can be applied to the proper continuous screening of water ecosystem toxicity.","Detection of Cr6+ by the sulfur oxidizing bacteria biosensor: effect of different physical factors Abs: A biosensor based on sulfur-oxidizing bacteria (SOB) for detection of toxic chemicals in water was developed. SOB are acidophilic microorganisms that get their energy through the oxidation of reduced sulfur compounds in the presence of oxygen to produce sulfuric acid. The reaction results in an increase in electrical conductivity (EC) and a decrease in pH. The bioassay is based on the inhibition of SOB in the presence of toxic chemicals by measuring changes in EC and pH. The effect of different physical factors such as HRT, inorganic sulfur (S°) particle size, and temperature on detection of Cr(6+) was studied. The detection of Cr(6+) (50 ppb) was improved by decreasing the hydraulic retention time (HRT) from 30 to 10 min and increasing S° particle size from 1 to 4.75 mm. Detection time was shorter at 30 °C compared to 45 °C and the SOB were active over a wide range of temperatures with a maximum temperature for growth at 45 °C. This novel biosensor is simple, highly sensitive to low Cr(6+) concentrations (50 ppb), and also minimizes detection time. The present findings can be applied to the proper continuous screening of water ecosystem toxicity."
1509911,Bajpai et al. 2012,"Application of Central Composite Design approach for removal of chromium (VI) from aqueous solution using weakly anionic resin: modeling, optimization, and study of interactive variables","In this paper, response surface methodology (RSM) approach using Central Composite Design (CCD) is applied to develop mathematical model and optimize process parameters for Cr (VI) removal from aqueous streams using weakly anionic resin Amberlite IRA 96. The individual and combined effect of four process parameters, i.e. contact time, initial solution pH, initial Cr (VI) concentration and resin dose on Cr adsorption were studied. Analysis of variance (ANOVA) showed the relative significance of process parameters in removal process. Initial solution pH and resin dose were found to be more significant than contact time and initial Cr (VI) concentration. The second-order regression model was developed to predict the removal efficiency using Design Expert software. The optimal conditions to remove Cr from aqueous solution at constant temperature of 30°C and stirring speed of 250 rpm were found to be contact time 62.5 min, pH 1.96, initial Cr (VI) concentration 145.4 mg/L, and resin dose 8.51 g/L. At these conditions, high removal efficiency (93.26%) was achieved. FTIR and EDX analysis were conducted to interpret the functional groups involved during the Cr-resin interaction.","Application of Central Composite Design approach for removal of chromium (VI) from aqueous solution using weakly anionic resin: modeling, optimization, and study of interactive variables Abs: In this paper, response surface methodology (RSM) approach using Central Composite Design (CCD) is applied to develop mathematical model and optimize process parameters for Cr (VI) removal from aqueous streams using weakly anionic resin Amberlite IRA 96. The individual and combined effect of four process parameters, i.e. contact time, initial solution pH, initial Cr (VI) concentration and resin dose on Cr adsorption were studied. Analysis of variance (ANOVA) showed the relative significance of process parameters in removal process. Initial solution pH and resin dose were found to be more significant than contact time and initial Cr (VI) concentration. The second-order regression model was developed to predict the removal efficiency using Design Expert software. The optimal conditions to remove Cr from aqueous solution at constant temperature of 30°C and stirring speed of 250 rpm were found to be contact time 62.5 min, pH 1.96, initial Cr (VI) concentration 145.4 mg/L, and resin dose 8.51 g/L. At these conditions, high removal efficiency (93.26%) was achieved. FTIR and EDX analysis were conducted to interpret the functional groups involved during the Cr-resin interaction."
1509910,Chen et al. 2012,Effects of sintering atmosphere on cement clinkers produced from chromium-bearing sludge,"The purpose of this study was to investigate the effects of sintering atmosphere (oxidizing and reducing) on the polymorphs of dicalcium silicates (Ca2SiO4, C2S) and on the chromium leaching of the belite-rich clinkers made from a chromium-bearing sludge. This sludge was generated in an electroplating factory, and in addition to chromium, it contained nickel, copper and zinc. In the clinker production, air was used as the oxidizing atmosphere, and carbon monoxide, which was produced by burning graphite with an insufficient amount of oxygen, was employed as the reducing atmosphere. Dicalcium silicates were substantially formed under both kinds of sintering atmosphere, but there was some nonhydraulic gamma-C2S in the clinkers produced under the oxidizing atmosphere. In addition, the amount of gamma-C2S decreased with the chromium-bearing sludge addition, whereas that of beta-C2S increased. The clinkers produced under the reducing atmosphere had less residual chromium, a finding that shows that more chromium was evaporated. However, the reducing atmosphere can decrease the proportion of hexavalent chromium (Cr(VI)) in the resulting clinkers. For other heavy metals, the residual amounts of nickel and copper generally increased with the sludge addition, but zinc was absent in most of the clinkers produced under the reducing atmosphere. This implies that the evaporation of zinc is much more significant than that of the other heavy metals under a reducing atmosphere. In the leaching tests, the concentrations of nickel, copper, and zinc were below the detection limits in all the leachates. In terms of chromium, the total leaching concentration was highly related to Cr(VI). The clinkers produced under the oxidizing atmosphere had high leaching concentrations of chromium, and thus failed to meet the regulatory limit. In contrast, the reducing atmosphere was effective in decreasing the chromium leaching, and it therefore makes the resulting cement clinkers more environmentally sound.","Effects of sintering atmosphere on cement clinkers produced from chromium-bearing sludge Abs: The purpose of this study was to investigate the effects of sintering atmosphere (oxidizing and reducing) on the polymorphs of dicalcium silicates (Ca2SiO4, C2S) and on the chromium leaching of the belite-rich clinkers made from a chromium-bearing sludge. This sludge was generated in an electroplating factory, and in addition to chromium, it contained nickel, copper and zinc. In the clinker production, air was used as the oxidizing atmosphere, and carbon monoxide, which was produced by burning graphite with an insufficient amount of oxygen, was employed as the reducing atmosphere. Dicalcium silicates were substantially formed under both kinds of sintering atmosphere, but there was some nonhydraulic gamma-C2S in the clinkers produced under the oxidizing atmosphere. In addition, the amount of gamma-C2S decreased with the chromium-bearing sludge addition, whereas that of beta-C2S increased. The clinkers produced under the reducing atmosphere had less residual chromium, a finding that shows that more chromium was evaporated. However, the reducing atmosphere can decrease the proportion of hexavalent chromium (Cr(VI)) in the resulting clinkers. For other heavy metals, the residual amounts of nickel and copper generally increased with the sludge addition, but zinc was absent in most of the clinkers produced under the reducing atmosphere. This implies that the evaporation of zinc is much more significant than that of the other heavy metals under a reducing atmosphere. In the leaching tests, the concentrations of nickel, copper, and zinc were below the detection limits in all the leachates. In terms of chromium, the total leaching concentration was highly related to Cr(VI). The clinkers produced under the oxidizing atmosphere had high leaching concentrations of chromium, and thus failed to meet the regulatory limit. In contrast, the reducing atmosphere was effective in decreasing the chromium leaching, and it therefore makes the resulting cement clinkers more environmentally sound."
1509909,Idris et al. 2012,Modified PVA-alginate encapsulated photocatalyst ferro photo gels for Cr(VI) reduction,In this study magnetic separable photocatalyst beads containing maghemite nanoparticles (?-Fe(2)O(3)) in polyvinyl alcohol (PVA) polymer were prepared and used in the reduction of Cr(VI) to Cr(III) in an aqueous solution under sunlight. The unique superparamagnetic property of the photocatalyst contributed by the ?-Fe(2)O(3) and robust property of PVA polymer allow the magnetic beads to be recovered easily and reused for at least 7 times without washing. The concentration of ?-Fe(2)O(3) was varied from 8% (v/v) to 27% (v/v) and the results revealed that the beads with 8% (v/v) ?-Fe(2)O(3) exhibited the best performance where Cr(VI) was reduced to Cr(III) in only 30 min under sunlight. The use of the PVA has improved the bead properties and life cycle of beads which is in line with sustainable practices.,Modified PVA-alginate encapsulated photocatalyst ferro photo gels for Cr(VI) reduction Abs: In this study magnetic separable photocatalyst beads containing maghemite nanoparticles (?-Fe(2)O(3)) in polyvinyl alcohol (PVA) polymer were prepared and used in the reduction of Cr(VI) to Cr(III) in an aqueous solution under sunlight. The unique superparamagnetic property of the photocatalyst contributed by the ?-Fe(2)O(3) and robust property of PVA polymer allow the magnetic beads to be recovered easily and reused for at least 7 times without washing. The concentration of ?-Fe(2)O(3) was varied from 8% (v/v) to 27% (v/v) and the results revealed that the beads with 8% (v/v) ?-Fe(2)O(3) exhibited the best performance where Cr(VI) was reduced to Cr(III) in only 30 min under sunlight. The use of the PVA has improved the bead properties and life cycle of beads which is in line with sustainable practices.
1509908,Taksir et al. 2012,Optimization of a histopathological biomarker for sphingomyelin accumulation in acid sphingomyelinase deficiency,"Niemann-Pick disease (types A and B), or acid sphingomyelinase deficiency, is an inherited deficiency of acid sphingomyelinase, resulting in intralysosomal accumulation of sphingomyelin in cells throughout the body, particularly within those of the reticuloendothelial system. These cellular changes result in hepatosplenomegaly and pulmonary infiltrates in humans. A knockout mouse model mimics many elements of human ASMD and is useful for studying disease histopathology. However, traditional formalin-fixation and paraffin embedding of ASMD tissues dissolves sphingomyelin, resulting in tissues with a foamy cell appearance, making quantitative analysis of the substrate difficult. To optimize substrate fixation and staining, a modified osmium tetroxide and potassium dichromate postfixation method was developed to preserve sphingomyelin in epon-araldite embedded tissue and pulmonary cytology specimens. After processing, semi-thin sections were incubated with tannic acid solution followed by staining with toluidine blue/borax. This modified method provides excellent preservation and staining contrast of sphingomyelin with other cell structures. The resulting high-resolution light microscopy sections permit digital quantification of sphingomyelin in light microscopic fields. A lysenin affinity stain for sphingomyelin was also developed for use on these semi-thin epon sections. Finally, ultrathin serial sections can be cut from these same tissue blocks and stained for ultrastructural examination by electron microscopy.","Optimization of a histopathological biomarker for sphingomyelin accumulation in acid sphingomyelinase deficiency Abs: Niemann-Pick disease (types A and B), or acid sphingomyelinase deficiency, is an inherited deficiency of acid sphingomyelinase, resulting in intralysosomal accumulation of sphingomyelin in cells throughout the body, particularly within those of the reticuloendothelial system. These cellular changes result in hepatosplenomegaly and pulmonary infiltrates in humans. A knockout mouse model mimics many elements of human ASMD and is useful for studying disease histopathology. However, traditional formalin-fixation and paraffin embedding of ASMD tissues dissolves sphingomyelin, resulting in tissues with a foamy cell appearance, making quantitative analysis of the substrate difficult. To optimize substrate fixation and staining, a modified osmium tetroxide and potassium dichromate postfixation method was developed to preserve sphingomyelin in epon-araldite embedded tissue and pulmonary cytology specimens. After processing, semi-thin sections were incubated with tannic acid solution followed by staining with toluidine blue/borax. This modified method provides excellent preservation and staining contrast of sphingomyelin with other cell structures. The resulting high-resolution light microscopy sections permit digital quantification of sphingomyelin in light microscopic fields. A lysenin affinity stain for sphingomyelin was also developed for use on these semi-thin epon sections. Finally, ultrathin serial sections can be cut from these same tissue blocks and stained for ultrastructural examination by electron microscopy."
1509907,Kushwaha et al. 2012,A spectroscopic study for understanding the speciation of Cr on palm shell based adsorbents and their application for the remediation of chrome plating effluents,Palm shell based adsorbents prepared under five different thermochemical conditions have been shown to be quite effective for removal of chromium (III and VI) from aqueous solutions. X-ray photoelectron spectroscopy (XPS) and Fourier Transform Infrared Spectroscopy (FT-IR) have been used to determine information about the speciation and binding of chromium on the adsorbents under study. X-ray photoelectron spectroscopy (XPS) studies indicate that oxidation of lignin moieties takes place concurrently to Cr(VI) reduction and leads to the formation of hydroxyl and carboxyl functions. The maximum adsorption capacity for hexavalent chromium was found to be about 313 mg/g in an acidic medium using PAPSP. This is comparable to other natural substrates and ordinary adsorbents. The efficacy of the adsorbents under study to remove chromium from plating waste water has been demonstrated.,A spectroscopic study for understanding the speciation of Cr on palm shell based adsorbents and their application for the remediation of chrome plating effluents Abs: Palm shell based adsorbents prepared under five different thermochemical conditions have been shown to be quite effective for removal of chromium (III and VI) from aqueous solutions. X-ray photoelectron spectroscopy (XPS) and Fourier Transform Infrared Spectroscopy (FT-IR) have been used to determine information about the speciation and binding of chromium on the adsorbents under study. X-ray photoelectron spectroscopy (XPS) studies indicate that oxidation of lignin moieties takes place concurrently to Cr(VI) reduction and leads to the formation of hydroxyl and carboxyl functions. The maximum adsorption capacity for hexavalent chromium was found to be about 313 mg/g in an acidic medium using PAPSP. This is comparable to other natural substrates and ordinary adsorbents. The efficacy of the adsorbents under study to remove chromium from plating waste water has been demonstrated.
1509906,Eleftheriou et al. 2013,Hexavalent chromium disrupts mitosis by stabilizing microtubules in Lens culinaris root tip cells,"Hexavalent chromium [Cr(VI)] is an accumulating environmental pollutant due to anthropogenic activities, toxic for humans, animals and plants. Therefore, the effects of Cr(VI) on dividing root cells of lentil (Lens culinaris) were investigated by tubulin immunofluorescence and DNA staining. In Cr(VI)-treated roots, cell divisions were perturbed, the chromosomes formed irregular aggregations, multinucleate cells were produced and tubulin clusters were entrapped within the nuclei. All cell cycle-specific microtubule (MT) arrays were affected, indicating a stabilizing effect of Cr(VI) on the MTs of L. culinaris. Besides, a time- and concentration-dependent gradual increase of acetylated ?-tubulin, an indicator of MT stabilization, was observed in Cr(VI)-treated roots by both immunofluorescence and western blotting. Evidence is also provided that reactive oxygen species (ROS) caused by Cr(VI), determined with the specific marker dichlorofluorescein, may be responsible for MT stabilization. Combined treatments with Cr(VI) and oryzalin revealed that Cr(VI) overcomes the depolymerizing ability of oryzalin, as it does experimentally introduced hydrogen peroxide, further supporting its stabilizing effect. In conclusion, it is suggested that the mitotic aberrations caused by Cr(VI) in L. culinaris root cells may be the result of MT stabilization rather than depolymerization, which consequently disturbs MT dynamics and their related functions.","Hexavalent chromium disrupts mitosis by stabilizing microtubules in Lens culinaris root tip cells Abs: Hexavalent chromium [Cr(VI)] is an accumulating environmental pollutant due to anthropogenic activities, toxic for humans, animals and plants. Therefore, the effects of Cr(VI) on dividing root cells of lentil (Lens culinaris) were investigated by tubulin immunofluorescence and DNA staining. In Cr(VI)-treated roots, cell divisions were perturbed, the chromosomes formed irregular aggregations, multinucleate cells were produced and tubulin clusters were entrapped within the nuclei. All cell cycle-specific microtubule (MT) arrays were affected, indicating a stabilizing effect of Cr(VI) on the MTs of L. culinaris. Besides, a time- and concentration-dependent gradual increase of acetylated ?-tubulin, an indicator of MT stabilization, was observed in Cr(VI)-treated roots by both immunofluorescence and western blotting. Evidence is also provided that reactive oxygen species (ROS) caused by Cr(VI), determined with the specific marker dichlorofluorescein, may be responsible for MT stabilization. Combined treatments with Cr(VI) and oryzalin revealed that Cr(VI) overcomes the depolymerizing ability of oryzalin, as it does experimentally introduced hydrogen peroxide, further supporting its stabilizing effect. In conclusion, it is suggested that the mitotic aberrations caused by Cr(VI) in L. culinaris root cells may be the result of MT stabilization rather than depolymerization, which consequently disturbs MT dynamics and their related functions."
1509905,Huang et al. ,Efficient Catalytic Reduction of Hexavalent Chromium Using Palladium Nanoparticle-Immobilized Electrospun Polymer Nanofibers,"We report a facile and economic approach to fabricating catalytic active palladium (Pd) nanoparticle (NP)-immobilized electrospun polyethyleneimine (PEI)/polyvinyl alcohol (PVA) nanofibers for catalytic reduction of hexavalent chromium (Cr(VI)) to trivalent chromium (Cr(III)). In this study, PEI/PVA nanofibrous mats were first electrospun from homogeneous mixture solution of PEI and PVA, followed by cross-linking with glutaraldehyde vapor to render the fibers with good water stability. The nanofibrous mats were then alternatively soaked in potassium tetrachloropallidate (K(2)PdCl(4)) and sodium borohydride solution, and the PdCl(4)(2-) anions complexed with the free amine groups of PEI were able to be reduced to form zero-valent Pd NPs. The formed Pd NP-containing PEI/PVA nanofibers were characterized by different techniques. We show that the immobilization of Pd NPs does not significantly change the morphology of the PEI/PVA nanofibers; instead the mechanical durability of the fibers is significantly improved. The formed Pd NPs with a mean diameter of 2.6 nm are quite uniformly distributed within the fibers with a small portion of particles having a denser distribution at the outer surface of the fibers. The catalytic activity and reusability of the fabricated Pd NP-containing fibrous mats were evaluated by transformation of Cr(VI) to Cr(III) in aqueous solution in the presence of a reducing agent. Our results reveal that the Pd NP-containing nanofibrous mats display an excellent catalytic activity and reusability for the reduction of Cr(VI) to Cr(III). The facile approach to fabricating metal NP-immobilized polymer nanofibers with a high surface area to volume ratio, enhanced mechanical durability, and uniform NP distribution may be extended to prepare different NP-immobilized fibrous systems for various applications in catalysis, sensing, environmental sciences, and biomedicine.","Efficient Catalytic Reduction of Hexavalent Chromium Using Palladium Nanoparticle-Immobilized Electrospun Polymer Nanofibers Abs: We report a facile and economic approach to fabricating catalytic active palladium (Pd) nanoparticle (NP)-immobilized electrospun polyethyleneimine (PEI)/polyvinyl alcohol (PVA) nanofibers for catalytic reduction of hexavalent chromium (Cr(VI)) to trivalent chromium (Cr(III)). In this study, PEI/PVA nanofibrous mats were first electrospun from homogeneous mixture solution of PEI and PVA, followed by cross-linking with glutaraldehyde vapor to render the fibers with good water stability. The nanofibrous mats were then alternatively soaked in potassium tetrachloropallidate (K(2)PdCl(4)) and sodium borohydride solution, and the PdCl(4)(2-) anions complexed with the free amine groups of PEI were able to be reduced to form zero-valent Pd NPs. The formed Pd NP-containing PEI/PVA nanofibers were characterized by different techniques. We show that the immobilization of Pd NPs does not significantly change the morphology of the PEI/PVA nanofibers; instead the mechanical durability of the fibers is significantly improved. The formed Pd NPs with a mean diameter of 2.6 nm are quite uniformly distributed within the fibers with a small portion of particles having a denser distribution at the outer surface of the fibers. The catalytic activity and reusability of the fabricated Pd NP-containing fibrous mats were evaluated by transformation of Cr(VI) to Cr(III) in aqueous solution in the presence of a reducing agent. Our results reveal that the Pd NP-containing nanofibrous mats display an excellent catalytic activity and reusability for the reduction of Cr(VI) to Cr(III). The facile approach to fabricating metal NP-immobilized polymer nanofibers with a high surface area to volume ratio, enhanced mechanical durability, and uniform NP distribution may be extended to prepare different NP-immobilized fibrous systems for various applications in catalysis, sensing, environmental sciences, and biomedicine."
1509904,Mulange Wa Mulange and  Garbers-Craig 2012,Stabilization of Cr(VI) from fine ferrochrome dust using exfoliated vermiculite,"This study proved that vermiculite, a natural occurring mineral, can effectively remove and stabilize Cr(VI) from fine ferrochrome dust leachate. Batch adsorption studies were carried out to determine the effect of pH, contact time and adsorbent dose on the removal of Cr(VI). The process was found to be highly pH dependent. The optimum conditions for the Cr(VI) removal are at a pH of 1.5, contact time of 2h and adsorbent dose of 10gL(-1). The stability of the Cr(VI)-loaded vermiculite remained unchanged after 12 months, when the vermiculite was evaluated with the ASTM and TCLP Cr(VI) leach methods. However, Cr(VI) desorption did take place when the Acid Rain Test was used. The adsorption kinetic data fits the pseudo-second order model, while the equilibrium data of Cr(VI) adsorption onto vermiculite are best described by the Langmuir isotherm. The presence of hydrobiotite and biotite in the industrial vermiculite slightly decreased the degree of adsorption of Cr(VI).","Stabilization of Cr(VI) from fine ferrochrome dust using exfoliated vermiculite Abs: This study proved that vermiculite, a natural occurring mineral, can effectively remove and stabilize Cr(VI) from fine ferrochrome dust leachate. Batch adsorption studies were carried out to determine the effect of pH, contact time and adsorbent dose on the removal of Cr(VI). The process was found to be highly pH dependent. The optimum conditions for the Cr(VI) removal are at a pH of 1.5, contact time of 2h and adsorbent dose of 10gL(-1). The stability of the Cr(VI)-loaded vermiculite remained unchanged after 12 months, when the vermiculite was evaluated with the ASTM and TCLP Cr(VI) leach methods. However, Cr(VI) desorption did take place when the Acid Rain Test was used. The adsorption kinetic data fits the pseudo-second order model, while the equilibrium data of Cr(VI) adsorption onto vermiculite are best described by the Langmuir isotherm. The presence of hydrobiotite and biotite in the industrial vermiculite slightly decreased the degree of adsorption of Cr(VI)."
1509903,Kost et al. 2012,Protein tyrosine phosphatase (PTP) inhibition enhances chromosomal stability after genotoxic stress: decreased chromosomal instability (CIN) at the expense of enhanced genomic instability (GIN)?,"Inappropriate survival signaling after DNA damage may facilitate clonal expansion of genetically compromised cells, and it is known that protein tyrosine phosphatase (PTP) inhibitors activate key survival pathways. In this study we employed the genotoxicant, hexavalent chromium [Cr(VI)], which is a well-documented carcinogen of occupational and environmental concern. Cr(VI) induces a complex array of DNA damage, including DNA double strand breaks (DSBs). We recently reported that PTP inhibition bypassed cell cycle arrest and abrogated Cr(VI)-induced clonogenic lethality. Notably, PTP inhibition resulted in an increase in forward mutations at the HPRT locus, supporting the hypothesis that PTP inhibition in the presence of DNA damage may lead to genomic instability (GIN), via cell cycle checkpoint bypass. The aim of the present study was to determine the effect of PTP inhibition on DNA DSB formation and chromosomal integrity after Cr(VI) exposure. Diploid human lung fibroblasts were treated with Cr(VI) in the presence or absence of the PTP inhibitor, sodium orthovanadate, for up to 24h, and cells were analyzed for DNA DSBs and chromosomal damage. Cr(VI) treatment induced a rapid increase in DNA DSBs, and a significant increase in total chromosomal damage (chromatid breaks and gaps) after 24h. In sharp contrast, PTP inhibition abrogated both DNA DSBs and chromosomal damage after Cr(VI) treatment. In summary, PTP inhibition in the face of Cr(VI) genotoxic stress decreases chromosomal instability (CIN) but increases mutagenesis, which we postulate to be a result of error-prone DNA repair.","Protein tyrosine phosphatase (PTP) inhibition enhances chromosomal stability after genotoxic stress: decreased chromosomal instability (CIN) at the expense of enhanced genomic instability (GIN)? Abs: Inappropriate survival signaling after DNA damage may facilitate clonal expansion of genetically compromised cells, and it is known that protein tyrosine phosphatase (PTP) inhibitors activate key survival pathways. In this study we employed the genotoxicant, hexavalent chromium [Cr(VI)], which is a well-documented carcinogen of occupational and environmental concern. Cr(VI) induces a complex array of DNA damage, including DNA double strand breaks (DSBs). We recently reported that PTP inhibition bypassed cell cycle arrest and abrogated Cr(VI)-induced clonogenic lethality. Notably, PTP inhibition resulted in an increase in forward mutations at the HPRT locus, supporting the hypothesis that PTP inhibition in the presence of DNA damage may lead to genomic instability (GIN), via cell cycle checkpoint bypass. The aim of the present study was to determine the effect of PTP inhibition on DNA DSB formation and chromosomal integrity after Cr(VI) exposure. Diploid human lung fibroblasts were treated with Cr(VI) in the presence or absence of the PTP inhibitor, sodium orthovanadate, for up to 24h, and cells were analyzed for DNA DSBs and chromosomal damage. Cr(VI) treatment induced a rapid increase in DNA DSBs, and a significant increase in total chromosomal damage (chromatid breaks and gaps) after 24h. In sharp contrast, PTP inhibition abrogated both DNA DSBs and chromosomal damage after Cr(VI) treatment. In summary, PTP inhibition in the face of Cr(VI) genotoxic stress decreases chromosomal instability (CIN) but increases mutagenesis, which we postulate to be a result of error-prone DNA repair."
1509902,Kavita and  Keharia 2012,Reduction of hexavalent chromium by Ochrobactrum intermedium BCR400 isolated from a chromium-contaminated soil,"Hexavalent chromium-resistant Ochrobactrum intermedium BCR400 was isolated from chromium contaminated soil collected from Vadodara, Gujarat. It reduced 100 mg Cr(VI)/L completely in 52 h with initial Cr(VI) reduction rate of 1.98 mg/L/h. The Cr(VI) reduction rate decreased with increase in Cr(VI) concentration from 100 to 500 mg/L. The addition of anthraquinone-2-sulphonic acid (AQS) to culture O. intermedium BCR400 significantly enhanced its chromium reduction rate. The activation energy of AQS-mediated Cr(VI) reduction (120.69 KJ/mol) was 1.1-fold lower than non-mediated Cr(VI) reduction. An increase in the activities of quinone reductase and chromate reductase in cells grown in presence of AQS/AQS + Cr(VI) suggests their role in reduction of Cr(VI) by O. intermedium. Both chromate reductase and quinone reductase activities were FAD independent, required NADH as reductant, displayed maximum activity at pH (7.0) and temperature (30 °C). Thus Cr(VI) bioremediation potential of O. intermedium can be enhanced by augmentation of system with AQS as redox mediator.","Reduction of hexavalent chromium by Ochrobactrum intermedium BCR400 isolated from a chromium-contaminated soil Abs: Hexavalent chromium-resistant Ochrobactrum intermedium BCR400 was isolated from chromium contaminated soil collected from Vadodara, Gujarat. It reduced 100 mg Cr(VI)/L completely in 52 h with initial Cr(VI) reduction rate of 1.98 mg/L/h. The Cr(VI) reduction rate decreased with increase in Cr(VI) concentration from 100 to 500 mg/L. The addition of anthraquinone-2-sulphonic acid (AQS) to culture O. intermedium BCR400 significantly enhanced its chromium reduction rate. The activation energy of AQS-mediated Cr(VI) reduction (120.69 KJ/mol) was 1.1-fold lower than non-mediated Cr(VI) reduction. An increase in the activities of quinone reductase and chromate reductase in cells grown in presence of AQS/AQS + Cr(VI) suggests their role in reduction of Cr(VI) by O. intermedium. Both chromate reductase and quinone reductase activities were FAD independent, required NADH as reductant, displayed maximum activity at pH (7.0) and temperature (30 °C). Thus Cr(VI) bioremediation potential of O. intermedium can be enhanced by augmentation of system with AQS as redox mediator."
1509901,Banfalvi et al. 2012,Chromatin changes induced by Pb and Cd in human cells,"Our earlier data on the apoptotic effects of heavy metals (Cd, Hg, Ni, CrVI, and Ag) and irradiation (gamma and UV-B) indicated that cellular effects exerted on chromatin structure differ from one other. These observations suggested that chromatin distortions could be characteristic to the genotoxic agent. This notion raised questions whether or not (a) a specific genotoxic agent causes the same chromatin changes in different cell types, (b) closely related toxic compounds could be distinguished based on their chromatin toxicity. To answer these questions we have compared Cd induced toxicity in different cell types. The same Cd-specific chromatin changes were seen in human K562, Chinese hamster ovary and murine preB cells. K562 cells were chosen for fluorescent microscopy to compare chromatin damages caused by Cd and Pb. Characteristic distortions allowed a clear distinction between Cd and Pb toxicity at micromolar concentrations. The visualization of these changes is relatively easy and fast carrying the potential of early detection of heavy metal poisoning.","Chromatin changes induced by Pb and Cd in human cells Abs: Our earlier data on the apoptotic effects of heavy metals (Cd, Hg, Ni, CrVI, and Ag) and irradiation (gamma and UV-B) indicated that cellular effects exerted on chromatin structure differ from one other. These observations suggested that chromatin distortions could be characteristic to the genotoxic agent. This notion raised questions whether or not (a) a specific genotoxic agent causes the same chromatin changes in different cell types, (b) closely related toxic compounds could be distinguished based on their chromatin toxicity. To answer these questions we have compared Cd induced toxicity in different cell types. The same Cd-specific chromatin changes were seen in human K562, Chinese hamster ovary and murine preB cells. K562 cells were chosen for fluorescent microscopy to compare chromatin damages caused by Cd and Pb. Characteristic distortions allowed a clear distinction between Cd and Pb toxicity at micromolar concentrations. The visualization of these changes is relatively easy and fast carrying the potential of early detection of heavy metal poisoning."
1509900,Narayani and  Vidya Shetty 2012,Characteristics of a novel Acinetobacter sp. and its kinetics in hexavalent chromium bioreduction,"Cr-B2, a Gram-negative hexavalent chromium [Cr(VI)] reducing bacteria, was isolated from the aerator water of an activated sludge process in the wastewater treatment facility of a dye and pigment based chemical industry. Cr- B2 exhibited a resistance for 1,100 mg/l Cr(VI) and, similarly, resistance against other heavy metal ions such as Ni2+ (800 mg/l), Cu2+ (600 mg/l), Pb2+ (1,100 mg/l), Cd2+ (350 mg/l), Zn2+ (700 mg/l), and Fe3+ (1,000 mg/l), and against selected antibiotics. Cr-B2 was observed to efficiently reduce 200 mg/l Cr(VI) completely in both nutrient and LB media, and could convert Cr(VI) to Cr(III) aerobically. Cr(VI) reduction kinetics followed allosteric enzyme kinetics. The Km values were found to be 43.11 mg/l for nutrient media and 38.05 mg/l for LB media. Vmax values of 13.17 mg/l/h and 12.53 mg/l/h were obtained for nutrient media and LB media, respectively, and the cooperativity coefficients (n) were found to be 8.47 and 3.49, respectively, indicating positive cooperativity in both cases. SEM analysis showed the formation of wrinkles and depressions in the cells when exposed to an 800 mg/l Cr(VI) concentration. The organism was seen to exhibit pleomorphic behavior. Cr-B2 was identified on the basis of morphological, biochemical, and partial 16S rRNA gene sequencing chracterizations and found to be Acinetobacter sp.","Characteristics of a novel Acinetobacter sp. and its kinetics in hexavalent chromium bioreduction Abs: Cr-B2, a Gram-negative hexavalent chromium [Cr(VI)] reducing bacteria, was isolated from the aerator water of an activated sludge process in the wastewater treatment facility of a dye and pigment based chemical industry. Cr- B2 exhibited a resistance for 1,100 mg/l Cr(VI) and, similarly, resistance against other heavy metal ions such as Ni2+ (800 mg/l), Cu2+ (600 mg/l), Pb2+ (1,100 mg/l), Cd2+ (350 mg/l), Zn2+ (700 mg/l), and Fe3+ (1,000 mg/l), and against selected antibiotics. Cr-B2 was observed to efficiently reduce 200 mg/l Cr(VI) completely in both nutrient and LB media, and could convert Cr(VI) to Cr(III) aerobically. Cr(VI) reduction kinetics followed allosteric enzyme kinetics. The Km values were found to be 43.11 mg/l for nutrient media and 38.05 mg/l for LB media. Vmax values of 13.17 mg/l/h and 12.53 mg/l/h were obtained for nutrient media and LB media, respectively, and the cooperativity coefficients (n) were found to be 8.47 and 3.49, respectively, indicating positive cooperativity in both cases. SEM analysis showed the formation of wrinkles and depressions in the cells when exposed to an 800 mg/l Cr(VI) concentration. The organism was seen to exhibit pleomorphic behavior. Cr-B2 was identified on the basis of morphological, biochemical, and partial 16S rRNA gene sequencing chracterizations and found to be Acinetobacter sp."
1509899,Lee and  Lim 2012,Inhibitory effect of Styrax Japonica Siebold et al. Zuccarini glycoprotein (38 kDa) on interleukin-1? and induction proteins in chromium(VI)-treated BNL CL.2 cells,"Chromium(VI) [Cr(VI)] induces chronic inflammation in hepatocytes. Inflammation has been shown to play an important role in tumorigenesis, tumor progression, and metastasis. To examine the effects of the Styrax Japonica Siebold et al. Zuccarini (SJSZ) glycoprotein on inflammation in BNL CL.2 cells, we evaluated the activities of c-Jun NH(2)-terminal kinase (JNK), extracellular signal-regulated kinase (ERK), nuclear factor (NF)-?B (p50 and p65), and inflammation-related factors [cyclooxygenase (COX)-2, inducible nitric oxide syntheses (iNOS) and interleukin (IL)-1?] in Cr-induced BNL CL.2 cells using immunoblot analysis and RT-PCR. We also used two-dimensional gel electrophoresis (2-DE) to compare between treatments. To determine which proteins are induced by Cr(VI), we evaluated total protein lysates using 2-DE. After Cr(VI) treatment, total protein lysates were prepared and resolved by 2-DE. The results obtained from this study demonstrated that the SJSZ glycoprotein (50 ?g/ml) inhibits expression of JNK, ERK, NF-?B, and the expression of COX-2, iNOS, and IL-1?. Moreover, the results obtained from 2DE showed that four proteins out of nine proteins were relatively expressed strongly, while the rest of them were relatively appeared weakly on the gel. Taken together, these data indicate that the SJSZ glycoprotein prevents expression of COX-2, iNOS, and IL-1? by blocking NF-?B and MAPKs in Cr(VI)-induced BNL CL.2 cells.","Inhibitory effect of Styrax Japonica Siebold et al. Zuccarini glycoprotein (38 kDa) on interleukin-1? and induction proteins in chromium(VI)-treated BNL CL.2 cells Abs: Chromium(VI) [Cr(VI)] induces chronic inflammation in hepatocytes. Inflammation has been shown to play an important role in tumorigenesis, tumor progression, and metastasis. To examine the effects of the Styrax Japonica Siebold et al. Zuccarini (SJSZ) glycoprotein on inflammation in BNL CL.2 cells, we evaluated the activities of c-Jun NH(2)-terminal kinase (JNK), extracellular signal-regulated kinase (ERK), nuclear factor (NF)-?B (p50 and p65), and inflammation-related factors [cyclooxygenase (COX)-2, inducible nitric oxide syntheses (iNOS) and interleukin (IL)-1?] in Cr-induced BNL CL.2 cells using immunoblot analysis and RT-PCR. We also used two-dimensional gel electrophoresis (2-DE) to compare between treatments. To determine which proteins are induced by Cr(VI), we evaluated total protein lysates using 2-DE. After Cr(VI) treatment, total protein lysates were prepared and resolved by 2-DE. The results obtained from this study demonstrated that the SJSZ glycoprotein (50 ?g/ml) inhibits expression of JNK, ERK, NF-?B, and the expression of COX-2, iNOS, and IL-1?. Moreover, the results obtained from 2DE showed that four proteins out of nine proteins were relatively expressed strongly, while the rest of them were relatively appeared weakly on the gel. Taken together, these data indicate that the SJSZ glycoprotein prevents expression of COX-2, iNOS, and IL-1? by blocking NF-?B and MAPKs in Cr(VI)-induced BNL CL.2 cells."
1509898,Li et al. 2012,"The hazardous hexavalent chromium formed on trivalent chromium conversion coating: The origin, influence factors and control measures","In this paper, the effects of processing parameters and constituents of treating-agent on the presence of hazardous hexavalent chromium on trivalent chromium conversion coating were studied. Results showed that shorter immersion time, lower bath pH value as well as lower working and baking temperatures retarded the presence of hexavalent chromium. In addition, the concentration of hexavalent chromium on conversion coatings prepared by the oxalic acid treating-agent was far greater than those on conversion coatings prepared by formic acid and acetic acid treating-agents. Results also indicated that the concentration of hexavalent chromium on conversion coatings was enhanced due to the addition of bivalent cobalt and nitrate anion in treating-agent, especially for oxalic acid conversion coating. However, the addition of hydroxyl compound d-gluconic acid in treating-agent could reduce the concentration of hexavalent chromium effectively. Moreover, a possible formation mechanism of hexavalent chromium on trivalent conversion coating was proposed. Findings of this study provide a better understanding of the formation of hexavalent chromium on trivalent chromium conversion coating and can facilitate the management of trivalent chromium treating-agents and trivalent chromium fasteners.","The hazardous hexavalent chromium formed on trivalent chromium conversion coating: The origin, influence factors and control measures Abs: In this paper, the effects of processing parameters and constituents of treating-agent on the presence of hazardous hexavalent chromium on trivalent chromium conversion coating were studied. Results showed that shorter immersion time, lower bath pH value as well as lower working and baking temperatures retarded the presence of hexavalent chromium. In addition, the concentration of hexavalent chromium on conversion coatings prepared by the oxalic acid treating-agent was far greater than those on conversion coatings prepared by formic acid and acetic acid treating-agents. Results also indicated that the concentration of hexavalent chromium on conversion coatings was enhanced due to the addition of bivalent cobalt and nitrate anion in treating-agent, especially for oxalic acid conversion coating. However, the addition of hydroxyl compound d-gluconic acid in treating-agent could reduce the concentration of hexavalent chromium effectively. Moreover, a possible formation mechanism of hexavalent chromium on trivalent conversion coating was proposed. Findings of this study provide a better understanding of the formation of hexavalent chromium on trivalent chromium conversion coating and can facilitate the management of trivalent chromium treating-agents and trivalent chromium fasteners."
1509897,Fargašová 2012,Plants as models for chromium and nickel risk assessment,"The adverse effects of Cr(III), Cr(VI), and Ni(II) expressed as root and shoot growth inhibition, metal accumulation and translocation throughout plants, and genotoxicity study were examined. To examine phytoxicity and metal accumulation, Vicia sativa, Raphanus sativus, Zea mays and Sinapis alba plants were used. Except for S. alba root growth inhibition, Ni had the strongest inhibitory effect on root and shoot growth. The inhibitory rank order based on IC?? values was Ni(II) &gt; Cr(VI) &gt; Cr(III). Z. mays was the least sensitive to all metals. While the accumulation of Cr was higher in the roots than the upper plant parts, Ni transport to shoots was at least two times higher than that of Cr. The highest accumulation of Cr was found in Z. mays and that of Ni in V. sativa and Z. mays roots. For all plants, the translocation factor was higher for Cr(VI) than for Cr(III). The translocation factor for Ni was several times higher than those of Cr. For mutagenicity assay, root tips of V. sativa, R. sativus and Z. mays were used. All metals exerted a significant increase of chromosomal aberrations and the rank order of aberrations was: Cr(VI) &gt; Ni(II) &gt; Cr(III). Genotoxic effects of metals were also determined by analysis of micronuclei frequency in the pollen tetrads of Tradescantia plants. None of metals significantly stimulated micronuclei frequency and the genotoxic effect decreased in the following order: Cr(VI) ? Ni(II) &gt; Cr(III).","Plants as models for chromium and nickel risk assessment Abs: The adverse effects of Cr(III), Cr(VI), and Ni(II) expressed as root and shoot growth inhibition, metal accumulation and translocation throughout plants, and genotoxicity study were examined. To examine phytoxicity and metal accumulation, Vicia sativa, Raphanus sativus, Zea mays and Sinapis alba plants were used. Except for S. alba root growth inhibition, Ni had the strongest inhibitory effect on root and shoot growth. The inhibitory rank order based on IC?? values was Ni(II) &gt; Cr(VI) &gt; Cr(III). Z. mays was the least sensitive to all metals. While the accumulation of Cr was higher in the roots than the upper plant parts, Ni transport to shoots was at least two times higher than that of Cr. The highest accumulation of Cr was found in Z. mays and that of Ni in V. sativa and Z. mays roots. For all plants, the translocation factor was higher for Cr(VI) than for Cr(III). The translocation factor for Ni was several times higher than those of Cr. For mutagenicity assay, root tips of V. sativa, R. sativus and Z. mays were used. All metals exerted a significant increase of chromosomal aberrations and the rank order of aberrations was: Cr(VI) &gt; Ni(II) &gt; Cr(III). Genotoxic effects of metals were also determined by analysis of micronuclei frequency in the pollen tetrads of Tradescantia plants. None of metals significantly stimulated micronuclei frequency and the genotoxic effect decreased in the following order: Cr(VI) ? Ni(II) &gt; Cr(III)."
1509896,Takami et al. 2012,"The interplay between thiol-compounds against chromium (VI) in the freshwater green alga Monoraphidium convolutum: toxicology, photosynthesis, and oxidative stress at a glance","In this paper, the multifaceted Cr(VI) toxicity over the freshwater green alga Monoraphidium convolutum was assessed by concomitantly monitoring thiol-dependent redox balances, photosynthesis activity and growth-survival scores. Control group showed exponential growth rate at (5.78±0.29) division/day until 8th day with linear increasing chlorophyll a/protein ratios (CHLa/PROT) throughout the period. Cultures of M. convolutum were exposed for 5 days to Cr(VI) concentrations from 0 up to 100mg/L showing that CHLa/PROT ratios were sensibly affected, in agreement to the calculated LC(50,48 h) (5.38±0.72) mg/L from the concentration-response curve of cell mortality after 48 h. Regarding photosynthesis effects, Cr(VI) concentrations &gt;1.0 mg/L showed significant increases in short-term (after 2 h) electron transfer rates (ETR) and quantum yields of photosystem II (?(PSII)), followed by subsequent decline of both parameters after 48 and 72 h. Biochemical analyses showed that maximal GSH concentrations in algal cultures were observed upon 1mg Cr(VI)/L and higher dichromate concentrations dramatically increased the activity of antioxidant GSH-dependent enzymes ascorbate peroxidase and glutathione reductase. However, no variation was observed in the cellular GSH levels, whereas GSSG and lipid peroxidation indexes abruptly increased upon 10 mg Cr(VI)/L exposure. Altogether, plant physiology, photosynthesis and biochemical data suggest that the GSH-dependent antioxidant system is capable to sustain M. convolutum viability through efficient photosynthesis activity and adequate antioxidant responses up to Cr(VI) concentrations of 1.0mg/L, when redox unbalances were first evidenced.","The interplay between thiol-compounds against chromium (VI) in the freshwater green alga Monoraphidium convolutum: toxicology, photosynthesis, and oxidative stress at a glance Abs: In this paper, the multifaceted Cr(VI) toxicity over the freshwater green alga Monoraphidium convolutum was assessed by concomitantly monitoring thiol-dependent redox balances, photosynthesis activity and growth-survival scores. Control group showed exponential growth rate at (5.78±0.29) division/day until 8th day with linear increasing chlorophyll a/protein ratios (CHLa/PROT) throughout the period. Cultures of M. convolutum were exposed for 5 days to Cr(VI) concentrations from 0 up to 100mg/L showing that CHLa/PROT ratios were sensibly affected, in agreement to the calculated LC(50,48 h) (5.38±0.72) mg/L from the concentration-response curve of cell mortality after 48 h. Regarding photosynthesis effects, Cr(VI) concentrations &gt;1.0 mg/L showed significant increases in short-term (after 2 h) electron transfer rates (ETR) and quantum yields of photosystem II (?(PSII)), followed by subsequent decline of both parameters after 48 and 72 h. Biochemical analyses showed that maximal GSH concentrations in algal cultures were observed upon 1mg Cr(VI)/L and higher dichromate concentrations dramatically increased the activity of antioxidant GSH-dependent enzymes ascorbate peroxidase and glutathione reductase. However, no variation was observed in the cellular GSH levels, whereas GSSG and lipid peroxidation indexes abruptly increased upon 10 mg Cr(VI)/L exposure. Altogether, plant physiology, photosynthesis and biochemical data suggest that the GSH-dependent antioxidant system is capable to sustain M. convolutum viability through efficient photosynthesis activity and adequate antioxidant responses up to Cr(VI) concentrations of 1.0mg/L, when redox unbalances were first evidenced."
1509895,Xiao et al. ,WITHDRAWN: Hexavalent chromium induces premature senescence through reactive oxygen species-mediated p53 pathway in L-02 hepatocytes,This article has been withdrawn at the request of the author(s) and/or editor. The Publisher apologizes for any inconvenience this may cause. The full Elsevier Policy on Article Withdrawal can be found at http://www.elsevier.com/locate/withdrawalpolicy.,WITHDRAWN: Hexavalent chromium induces premature senescence through reactive oxygen species-mediated p53 pathway in L-02 hepatocytes Abs: This article has been withdrawn at the request of the author(s) and/or editor. The Publisher apologizes for any inconvenience this may cause. The full Elsevier Policy on Article Withdrawal can be found at http://www.elsevier.com/locate/withdrawalpolicy.
1509894,Wang et al. 2012,Modified mesoporous silica materials for on-line separation and preconcentration of hexavalent chromium using a microcolumn coupled with flame atomic absorption spectrometry,"A modified SBA-15 mesoporous silica material NH(2)-SBA-15 was synthesized successfully by grafting ?-aminopropyl-triethoxysilane. The material was characterized using transmission electron microscopy (TEM) and Fourier transform infrared/Raman (FT-IR/Raman) spectroscopy, and used for the first time in a flow injection on-line solid phase extraction (SPE) coupled with flame atomic absorption spectrometry (FAAS) to detect trace Cr (VI). Effective sorption of Cr (VI) was achieved at pH 2.0 with no interference from Cr (III) and other ions and 0.5 mol L(-1) NH(3)·H(2)O solution was found optimal for the complete elution of Cr (VI). An enrichment factor of 44 and was achieved under optimized experimental conditions at a sample loading of 2.0 mL min(-1) sample loading (300 s) and an elution flow rate of 2.0 mL min(-1) (24s). The precision of the 11 replicate Cr (VI) measurements was 2.1% at the 100 ?g L(-1) level with a detection limit of 0.2 ?g L(-1) (3s, n=10) using the FAAS. The developed method was successfully applied to trace chromium determination in waste water. The accuracy was validated using a certified reference material of riverine water (GBW08607).","Modified mesoporous silica materials for on-line separation and preconcentration of hexavalent chromium using a microcolumn coupled with flame atomic absorption spectrometry Abs: A modified SBA-15 mesoporous silica material NH(2)-SBA-15 was synthesized successfully by grafting ?-aminopropyl-triethoxysilane. The material was characterized using transmission electron microscopy (TEM) and Fourier transform infrared/Raman (FT-IR/Raman) spectroscopy, and used for the first time in a flow injection on-line solid phase extraction (SPE) coupled with flame atomic absorption spectrometry (FAAS) to detect trace Cr (VI). Effective sorption of Cr (VI) was achieved at pH 2.0 with no interference from Cr (III) and other ions and 0.5 mol L(-1) NH(3)·H(2)O solution was found optimal for the complete elution of Cr (VI). An enrichment factor of 44 and was achieved under optimized experimental conditions at a sample loading of 2.0 mL min(-1) sample loading (300 s) and an elution flow rate of 2.0 mL min(-1) (24s). The precision of the 11 replicate Cr (VI) measurements was 2.1% at the 100 ?g L(-1) level with a detection limit of 0.2 ?g L(-1) (3s, n=10) using the FAAS. The developed method was successfully applied to trace chromium determination in waste water. The accuracy was validated using a certified reference material of riverine water (GBW08607)."
1509893,Paul et al. 2012,Induction of Cr(VI) reduction activity in an Anoxybacillus strain under heat stress: a biochemical and proteomic study,"A bacterial strain, designated as TSB-6, was isolated from the sediments of a Tantloi (India) hot spring at 65 °C. The strain showed 98% 16S rRNA gene sequence similarity with Anoxybacillus kualawohkensis strain KW12 and was found to grow optimally at 37 °C. However, growing cells, cell suspensions, and cell-free extracts from 65 °C cultures showed higher Cr(VI) reduction activities when assayed at either 37 or 65 °C than those obtained from 37 °C cultures. On fractionation of extracts from cells grown at 65 °C, the chromate reductase activity assayed at 65 °C was found mostly in the soluble fraction. When log-phase cells growing at 37 °C were shifted to 65 °C, the stressed cells produced larger quantities of reactive oxygen species. Consequently, growth of the cells was retarded, but specific Cr(VI) reduction activity increased. 2D gel electrophoresis followed by MALDI-TOF MS/MS identified the proteins whose expression level changed as a result of heat stress. The upregulated set included proteins involved in cellular metabolism of sugar, nucleotide, amino acids, lipids and vitamins, oxidoreductase activity, and protein folding. The downregulated proteins are also involved in cellular metabolism, DNA binding, and environmental signal processing.","Induction of Cr(VI) reduction activity in an Anoxybacillus strain under heat stress: a biochemical and proteomic study Abs: A bacterial strain, designated as TSB-6, was isolated from the sediments of a Tantloi (India) hot spring at 65 °C. The strain showed 98% 16S rRNA gene sequence similarity with Anoxybacillus kualawohkensis strain KW12 and was found to grow optimally at 37 °C. However, growing cells, cell suspensions, and cell-free extracts from 65 °C cultures showed higher Cr(VI) reduction activities when assayed at either 37 or 65 °C than those obtained from 37 °C cultures. On fractionation of extracts from cells grown at 65 °C, the chromate reductase activity assayed at 65 °C was found mostly in the soluble fraction. When log-phase cells growing at 37 °C were shifted to 65 °C, the stressed cells produced larger quantities of reactive oxygen species. Consequently, growth of the cells was retarded, but specific Cr(VI) reduction activity increased. 2D gel electrophoresis followed by MALDI-TOF MS/MS identified the proteins whose expression level changed as a result of heat stress. The upregulated set included proteins involved in cellular metabolism of sugar, nucleotide, amino acids, lipids and vitamins, oxidoreductase activity, and protein folding. The downregulated proteins are also involved in cellular metabolism, DNA binding, and environmental signal processing."
1509892,Ouyang et al. 2012,Flower-like self-assembly of gold nanoparticles for highly sensitive electrochemical detection of chromium(VI),"We report here the fabrication of a flower-like self-assembly of gold nanoparticles (AuNPs) on a glassy carbon electrode (GCE) as a highly sensitive platform for ultratrace Cr(VI) detection. Two AuNP layers are used in the current approach, in which the first is electroplated on the GCE surface as anchors for binding to an overcoated thiol sol-gel film derived from 3-mercaptopropyltrimethoxysilane (MPTS). The second AuNP layer is then self-assembled on the surface of the sol-gel film, forming flower-like gold nanoelectrodes enlarging the electrode surface. When functionalized by a thiol pyridinium, the fabricated electrode displays a well-defined peak for selective Cr(VI) reduction with an unusually large, linear concentration range of 10-1200 ng L(-1) and a low detection limit of 2.9 ng L(-1). In comparison to previous approaches using MPTS and AuNPs on Au electrodes, the current work expands the use of AuNPs to the GCE. Subsequent functionalization of the secondary AuNPs by a thiol pyridinium and adsorption/preconcentration of Cr(VI) lead to the unusually large detection range and high sensitivity. The stepwise preparation of the electrode has been characterized by electrochemical impedance spectroscopy (EIS), scanning electronic microscopy (SEM), and IR. The newly designed electrode exhibits good stability, and has been successfully employed to measure chromium in a pre-treated blood sample. The method demonstrates acceptable fabrication reproducibility and accuracy.","Flower-like self-assembly of gold nanoparticles for highly sensitive electrochemical detection of chromium(VI) Abs: We report here the fabrication of a flower-like self-assembly of gold nanoparticles (AuNPs) on a glassy carbon electrode (GCE) as a highly sensitive platform for ultratrace Cr(VI) detection. Two AuNP layers are used in the current approach, in which the first is electroplated on the GCE surface as anchors for binding to an overcoated thiol sol-gel film derived from 3-mercaptopropyltrimethoxysilane (MPTS). The second AuNP layer is then self-assembled on the surface of the sol-gel film, forming flower-like gold nanoelectrodes enlarging the electrode surface. When functionalized by a thiol pyridinium, the fabricated electrode displays a well-defined peak for selective Cr(VI) reduction with an unusually large, linear concentration range of 10-1200 ng L(-1) and a low detection limit of 2.9 ng L(-1). In comparison to previous approaches using MPTS and AuNPs on Au electrodes, the current work expands the use of AuNPs to the GCE. Subsequent functionalization of the secondary AuNPs by a thiol pyridinium and adsorption/preconcentration of Cr(VI) lead to the unusually large detection range and high sensitivity. The stepwise preparation of the electrode has been characterized by electrochemical impedance spectroscopy (EIS), scanning electronic microscopy (SEM), and IR. The newly designed electrode exhibits good stability, and has been successfully employed to measure chromium in a pre-treated blood sample. The method demonstrates acceptable fabrication reproducibility and accuracy."
1509891,Suksabye and  Thiravetyan 2012,Cr(VI) adsorption from electroplating plating wastewater by chemically modified coir pith,"Coir pith samples were chemically modified by grafting with acrylic acid for the removal of Cr(VI) from electroplating wastewater. The presence of acrylic acid on the coir pith surface was verified by a scanning electron microscope with an electron dispersive x-ray spectrometer (SEM/EDX), Fourier transform infrared spectroscopy (FTIR) and thermogravimetry (TG). The carbonyl groups (C==O) from the carboxylic acids (COOH) increased on the coir pith surface after grafting with acrylic acid. In addition, the thermal stability of the acrylic acid-grafted coir pith also improved. The optimum conditions for grafting the acrylic acid on the coir pith consisted of 2 M acrylic acid and 0.00125 M ceric ammonium nitrate (CAN, as an initiator). The maximum Cr(VI) removal (99.99 ± 0.07%) was obtained with the following conditions: a 1.3% (w/v) dosage of acrylic acid-grafted coir pith, a system pH of 2, a contact time of 22 h, a temperature of 30 °C, a particle size of &lt;150 ?m and an initial Cr(VI) of 1,171 mg l(-1). At system pH of 2, Cr(VI) in the HCrO(4)(-) form can be adsorbed with acrylic acid-grafted coir pith via an electrostatic attraction. The adsorption isotherm of 2 M acrylic acid-grafted coir pith exhibited a good fit with the Langmuir isotherm. The maximum Cr(VI) adsorption capacity of the 2 M acrylic acid-grafted coir pith was 196.00 mg Cr(VI) g(-1) adsorbent, whereas for coir pith without grafting, the maximum Cr(VI) removal was 165.00 mg Cr(VI) g(-1) adsorbent. The adsorption capacity of the acrylic acid-grafted coir pith for Cr(VI) was higher compared to the original coir pith. This result was due to the enhancement of the carbonyl groups on the coir pith surface that may have involved the mechanism of chromium adsorption. The X-ray absorption near edged structure (XANES) and desorption studies suggested that most of the Cr(III) that presented on the acrylic acid-grafted coir pith was due to the Cr(VI) being reduced to Cr(III) on the adsorbent surface. FTIR confirmed the involvement of the carbonyl groups (C==O) and the methoxy groups (OCH3) in the mechanism of chromium adsorption. Thermodynamic study, such as enthalpy (?H), free energy (?G) and entropy change (?S) indicated that the overall adsorption process was endothermic, spontaneous and randomness. In addition, the adsorption process was favored at high temperatures.","Cr(VI) adsorption from electroplating plating wastewater by chemically modified coir pith Abs: Coir pith samples were chemically modified by grafting with acrylic acid for the removal of Cr(VI) from electroplating wastewater. The presence of acrylic acid on the coir pith surface was verified by a scanning electron microscope with an electron dispersive x-ray spectrometer (SEM/EDX), Fourier transform infrared spectroscopy (FTIR) and thermogravimetry (TG). The carbonyl groups (C==O) from the carboxylic acids (COOH) increased on the coir pith surface after grafting with acrylic acid. In addition, the thermal stability of the acrylic acid-grafted coir pith also improved. The optimum conditions for grafting the acrylic acid on the coir pith consisted of 2 M acrylic acid and 0.00125 M ceric ammonium nitrate (CAN, as an initiator). The maximum Cr(VI) removal (99.99 ± 0.07%) was obtained with the following conditions: a 1.3% (w/v) dosage of acrylic acid-grafted coir pith, a system pH of 2, a contact time of 22 h, a temperature of 30 °C, a particle size of &lt;150 ?m and an initial Cr(VI) of 1,171 mg l(-1). At system pH of 2, Cr(VI) in the HCrO(4)(-) form can be adsorbed with acrylic acid-grafted coir pith via an electrostatic attraction. The adsorption isotherm of 2 M acrylic acid-grafted coir pith exhibited a good fit with the Langmuir isotherm. The maximum Cr(VI) adsorption capacity of the 2 M acrylic acid-grafted coir pith was 196.00 mg Cr(VI) g(-1) adsorbent, whereas for coir pith without grafting, the maximum Cr(VI) removal was 165.00 mg Cr(VI) g(-1) adsorbent. The adsorption capacity of the acrylic acid-grafted coir pith for Cr(VI) was higher compared to the original coir pith. This result was due to the enhancement of the carbonyl groups on the coir pith surface that may have involved the mechanism of chromium adsorption. The X-ray absorption near edged structure (XANES) and desorption studies suggested that most of the Cr(III) that presented on the acrylic acid-grafted coir pith was due to the Cr(VI) being reduced to Cr(III) on the adsorbent surface. FTIR confirmed the involvement of the carbonyl groups (C==O) and the methoxy groups (OCH3) in the mechanism of chromium adsorption. Thermodynamic study, such as enthalpy (?H), free energy (?G) and entropy change (?S) indicated that the overall adsorption process was endothermic, spontaneous and randomness. In addition, the adsorption process was favored at high temperatures."
1509890,Du et al. 2012,Reduction and immobilization of chromate in chromite ore processing residue with nanoscale zero-valent iron,"Chromite ore processing residue (COPR) poses a great environmental and health risk with persistent Cr(VI) leaching. To reduce Cr(VI) and subsequently immobilize in the solid matrix, COPR was incubated with nanoscale zero-valent iron (nZVI) and the Cr(VI) speciation and leachability were studied. Multiple complementary analysis methods including leaching tests, X-ray powder diffraction, X-ray absorption near edge structure (XANES) spectroscopy, and X-ray photoelectron spectroscopy (XPS) were employed to investigate the immobilization mechanism. Geochemical PHREEQC model calculation agreed well with our acid neutralizing capacity experimental results and confirmed that when pH was lowered from 11.7 to 7.0, leachate Cr(VI) concentrations were in the range 358-445mgL(-1) which contributed over 90% of dissolved Cr from COPR. Results of alkaline digestion, XANES, and XPS demonstrated that incubation COPR with nZVI under water content higher than 27% could result in a nearly complete Cr(VI) reduction in solids and less than 0.1mgL(-1) Cr(VI) in the TCLP leachate. The results indicated that remediation approaches using nZVI to reduce Cr(VI) in COPR should be successful with sufficient water content to facilitate electron transfer from nZVI to COPR.","Reduction and immobilization of chromate in chromite ore processing residue with nanoscale zero-valent iron Abs: Chromite ore processing residue (COPR) poses a great environmental and health risk with persistent Cr(VI) leaching. To reduce Cr(VI) and subsequently immobilize in the solid matrix, COPR was incubated with nanoscale zero-valent iron (nZVI) and the Cr(VI) speciation and leachability were studied. Multiple complementary analysis methods including leaching tests, X-ray powder diffraction, X-ray absorption near edge structure (XANES) spectroscopy, and X-ray photoelectron spectroscopy (XPS) were employed to investigate the immobilization mechanism. Geochemical PHREEQC model calculation agreed well with our acid neutralizing capacity experimental results and confirmed that when pH was lowered from 11.7 to 7.0, leachate Cr(VI) concentrations were in the range 358-445mgL(-1) which contributed over 90% of dissolved Cr from COPR. Results of alkaline digestion, XANES, and XPS demonstrated that incubation COPR with nZVI under water content higher than 27% could result in a nearly complete Cr(VI) reduction in solids and less than 0.1mgL(-1) Cr(VI) in the TCLP leachate. The results indicated that remediation approaches using nZVI to reduce Cr(VI) in COPR should be successful with sufficient water content to facilitate electron transfer from nZVI to COPR."
1509889,Crean et al. 2012,Engineering biogenic magnetite for sustained Cr(VI) remediation in flow-through systems,"In this work, we report a route to enhance the reactivity and longevity of biogenic magnetite in Cr(VI) remediation under continuous-flow conditions by combining functionalization of the biomagnetite surface with a precious metal catalyst, nanoscale palladium, and exposure to formate. Column influent conditions were varied to simulate oxic, anoxic, and nitrate cocontaminated environments. The addition of sodium formate as an electron donor for Pd-functionalized magnetite increased capacity and longevity allowing 80% removal of Cr(VI) after 300 h in anoxic conditions, whereas complete breakthrough occurred after 60 h in anoxic nonformate and nonfunctionalized systems. Removal of Cr(VI) was optimized under anoxic conditions, and the presence of oxidizing agents results in a modest loss in reductive capacity. Examination of reacted Pd-functionalized magnetite reveals close association of Fe with Cr, suggesting that Pd-coupled oxidation of formate serves to regenerate the reactive surface. XMCD studies revealed that Cr(III) is partially substituted for Fe in the magnetite structure, which serves to immobilize Cr. No evidence for a mechanistic interference by nitrate cocontamination was observed, suggesting that this novel system could provide robust, effective and sustained reduction of contaminants, even in the presence of common oxidizing cocontaminants, outperforming the reductive capacity of nonfunctionalized biogenic magnetite.","Engineering biogenic magnetite for sustained Cr(VI) remediation in flow-through systems Abs: In this work, we report a route to enhance the reactivity and longevity of biogenic magnetite in Cr(VI) remediation under continuous-flow conditions by combining functionalization of the biomagnetite surface with a precious metal catalyst, nanoscale palladium, and exposure to formate. Column influent conditions were varied to simulate oxic, anoxic, and nitrate cocontaminated environments. The addition of sodium formate as an electron donor for Pd-functionalized magnetite increased capacity and longevity allowing 80% removal of Cr(VI) after 300 h in anoxic conditions, whereas complete breakthrough occurred after 60 h in anoxic nonformate and nonfunctionalized systems. Removal of Cr(VI) was optimized under anoxic conditions, and the presence of oxidizing agents results in a modest loss in reductive capacity. Examination of reacted Pd-functionalized magnetite reveals close association of Fe with Cr, suggesting that Pd-coupled oxidation of formate serves to regenerate the reactive surface. XMCD studies revealed that Cr(III) is partially substituted for Fe in the magnetite structure, which serves to immobilize Cr. No evidence for a mechanistic interference by nitrate cocontamination was observed, suggesting that this novel system could provide robust, effective and sustained reduction of contaminants, even in the presence of common oxidizing cocontaminants, outperforming the reductive capacity of nonfunctionalized biogenic magnetite."
1509888,Chen et al. 2012,Use of synchrotron XANES and Cr-doped coal to further confirm the vaporization of organically bound Cr and the formation of chromium(VI) during coal oxy-fuel combustion,"Through the use of synchrotron XANES and Cr-doped brown coal, extensive efforts have been made to clarify the volatility of organically bound Cr during oxy-fuel combustion and the mode of occurrence and leachability of Cr in resulting fly ashes. As the continuation of our previous study using raw coal, the Cr-doped coal has been tested in this study to improve the signal-to-noise ratio for Cr K-edge XANES spectra, and hence the accuracy for Cr(VI) quantification. As has been confirmed, the abundant CO(2) as a balance gas for oxy-firing has the potential to inhibit the decomposition of organically bound Cr, thereby favoring its retention in solid ash. It also has the potential to promote the oxidation of Cr(III) to Cr(VI) to a minor extent. Increasing the oxygen partial pressure, particularly in the coexistence of HCl in flue gas, favored the oxidation of Cr(III) into gaseous Cr(VI)-bearing species such as CrO(2)Cl(2). Regarding the solid impurities including Na(2)SO(4) and CaO, Na(2)SO(4) has proven to preferentially capture the Cr(III)-bearing species at a low furnace temperature such as 600 °C. Its promoting effect on the oxidation of Cr(III) to Cr(VI), although thermodynamically available at the temperatures examined here, is negligible in a lab-scale drop tube furnace (DTF), where the particle residence time is extremely short. In contrast, CaO has proven facilitating the capture of Cr(VI)-bearing species particularly oxychloride vapors at 1000 °C, forming Ca chromate with the formulas of CaCrO(4) and Ca(3)(CrO(4))(2) via a direction stabilization of Cr(VI) oxychloride vapor by CaO particle or an indirect oxidation of Cr(III) via the initial formation of Ca chromite. The fly ash collected from the combustion of Cr-doped coal alone has a lower water solubility (i.e., 58.7%) for its Cr(VI) species, due to the formation of Ba/Pb chromate and/or the incorporation of Cr(VI) vapor into a slagging phase which is water-insoluble. Adding CaO to coal increased the water-solubility of both Cr(VI) and Cr(III) by forming Ca chromite and chromate, respectively.","Use of synchrotron XANES and Cr-doped coal to further confirm the vaporization of organically bound Cr and the formation of chromium(VI) during coal oxy-fuel combustion Abs: Through the use of synchrotron XANES and Cr-doped brown coal, extensive efforts have been made to clarify the volatility of organically bound Cr during oxy-fuel combustion and the mode of occurrence and leachability of Cr in resulting fly ashes. As the continuation of our previous study using raw coal, the Cr-doped coal has been tested in this study to improve the signal-to-noise ratio for Cr K-edge XANES spectra, and hence the accuracy for Cr(VI) quantification. As has been confirmed, the abundant CO(2) as a balance gas for oxy-firing has the potential to inhibit the decomposition of organically bound Cr, thereby favoring its retention in solid ash. It also has the potential to promote the oxidation of Cr(III) to Cr(VI) to a minor extent. Increasing the oxygen partial pressure, particularly in the coexistence of HCl in flue gas, favored the oxidation of Cr(III) into gaseous Cr(VI)-bearing species such as CrO(2)Cl(2). Regarding the solid impurities including Na(2)SO(4) and CaO, Na(2)SO(4) has proven to preferentially capture the Cr(III)-bearing species at a low furnace temperature such as 600 °C. Its promoting effect on the oxidation of Cr(III) to Cr(VI), although thermodynamically available at the temperatures examined here, is negligible in a lab-scale drop tube furnace (DTF), where the particle residence time is extremely short. In contrast, CaO has proven facilitating the capture of Cr(VI)-bearing species particularly oxychloride vapors at 1000 °C, forming Ca chromate with the formulas of CaCrO(4) and Ca(3)(CrO(4))(2) via a direction stabilization of Cr(VI) oxychloride vapor by CaO particle or an indirect oxidation of Cr(III) via the initial formation of Ca chromite. The fly ash collected from the combustion of Cr-doped coal alone has a lower water solubility (i.e., 58.7%) for its Cr(VI) species, due to the formation of Ba/Pb chromate and/or the incorporation of Cr(VI) vapor into a slagging phase which is water-insoluble. Adding CaO to coal increased the water-solubility of both Cr(VI) and Cr(III) by forming Ca chromite and chromate, respectively."
1509887,Ren et al. 2013,Synthesis of ?-Fe2O3 nanofibers for applications in removal and recovery of Cr(VI) from wastewater,"<strong>PURPOSE: </strong>Nanomaterials such as iron oxides and ferrites have been intensively investigated for water treatment and environmental remediation applications. The purpose of this work is to synthesize ?-Fe(2)O(3) nanofibers for potential applications in removal and recovery of noxious Cr(VI) from wastewater.<br /><br /><strong>METHODS: </strong>?-Fe(2)O(3) nanofibers were synthesized via a simple hydrothermal route followed by calcination. The crystallographic structure and the morphology of the as-prepared ?-Fe(2)O(3) nanofibers were characterized by X-ray diffraction, scanning electron microscope, and transmission electron microscope. Batch adsorption experiments were conducted, and Fourier transform infrared spectra were recorded before and after adsorption to investigate the Cr(VI) removal performance and adsorption mechanism. Langmuir and Freundlich modes were employed to analyze the adsorption behavior of Cr(VI) on the ?-Fe(2)O(3) nanofibers.<br /><br /><strong>RESULTS: </strong>Very thin and porous ?-Fe(2)O(3) nanofibers have been successfully synthesized for investigation of Cr(VI) removal capability from synthetic wastewater. Batch experiments revealed that the as-prepared ?-Fe(2)O(3) nanofibers exhibited excellent Cr(VI) removal performance with a maximum adsorption capacity of 16.17 mg g(-1). Furthermore, the adsorption capacity almost kept unchanged after recycling and reusing. The Cr(VI) adsorption process was found to follow the pseudo-second-order kinetics model, and the corresponding thermodynamic parameters ?G°, ?H°, and ?S° at 298 K were calculated to be -26.60 kJ mol(-1), -3.32 kJ mol(-1), and 78.12 J mol(-1) K(-1), respectively.<br /><br /><strong>CONCLUSIONS: </strong>The as-prepared ?-Fe(2)O(3) nanofibers can be utilized as efficient low-cost nano-absorbents for removal and recovery of Cr(VI) from wastewater.","Synthesis of ?-Fe2O3 nanofibers for applications in removal and recovery of Cr(VI) from wastewater Abs: <strong>PURPOSE: </strong>Nanomaterials such as iron oxides and ferrites have been intensively investigated for water treatment and environmental remediation applications. The purpose of this work is to synthesize ?-Fe(2)O(3) nanofibers for potential applications in removal and recovery of noxious Cr(VI) from wastewater.<br /><br /><strong>METHODS: </strong>?-Fe(2)O(3) nanofibers were synthesized via a simple hydrothermal route followed by calcination. The crystallographic structure and the morphology of the as-prepared ?-Fe(2)O(3) nanofibers were characterized by X-ray diffraction, scanning electron microscope, and transmission electron microscope. Batch adsorption experiments were conducted, and Fourier transform infrared spectra were recorded before and after adsorption to investigate the Cr(VI) removal performance and adsorption mechanism. Langmuir and Freundlich modes were employed to analyze the adsorption behavior of Cr(VI) on the ?-Fe(2)O(3) nanofibers.<br /><br /><strong>RESULTS: </strong>Very thin and porous ?-Fe(2)O(3) nanofibers have been successfully synthesized for investigation of Cr(VI) removal capability from synthetic wastewater. Batch experiments revealed that the as-prepared ?-Fe(2)O(3) nanofibers exhibited excellent Cr(VI) removal performance with a maximum adsorption capacity of 16.17 mg g(-1). Furthermore, the adsorption capacity almost kept unchanged after recycling and reusing. The Cr(VI) adsorption process was found to follow the pseudo-second-order kinetics model, and the corresponding thermodynamic parameters ?G°, ?H°, and ?S° at 298 K were calculated to be -26.60 kJ mol(-1), -3.32 kJ mol(-1), and 78.12 J mol(-1) K(-1), respectively.<br /><br /><strong>CONCLUSIONS: </strong>The as-prepared ?-Fe(2)O(3) nanofibers can be utilized as efficient low-cost nano-absorbents for removal and recovery of Cr(VI) from wastewater."
1509886,Lu et al. 2012,Electrochemical depassivation for recovering Fe(0) reactivity by Cr(VI) removal with a permeable reactive barrier system,"A new electrochemical permeable reactive barrier (Electro-PRB) system for removal of hexavalent chromium [Cr(VI)] using Fe(0) meshes was developed. Electro-PRB was found to be effective for electrochemical depassivation of Fe(0) to remove Cr(VI) during treatment. During initial treatment, Cr(VI) removal rates decreased with time, due to loss of Fe(0) reactivity by mineral fouling. After Fe(0) was passivated, electrochemical depassivation was introduced for different electrolysis times to recover Fe(0) reactivity. It was found that there was approximately 100.4-131.3% initial removal rate recovery, due to the electrochemical break down of precipitates on the Fe(0) surfaces. During the treatment, the decreasing pH and increasing oxidation-reduction Potential (ORP) of the effluent implied the passivation of Fe(0) surfaces. Scanning electron microscope analysis of acid-washed, electrochemically depassivated, and passivated Fe(0) confirmed the efficiency of Elecro-PRB in the recovery Fe(0) reactivity. The results indicate that the Electro-PRB system proposed here is capable of recovering the reactivity of Fe(0), which may prolong the operation of Cr(VI) removal processes.","Electrochemical depassivation for recovering Fe(0) reactivity by Cr(VI) removal with a permeable reactive barrier system Abs: A new electrochemical permeable reactive barrier (Electro-PRB) system for removal of hexavalent chromium [Cr(VI)] using Fe(0) meshes was developed. Electro-PRB was found to be effective for electrochemical depassivation of Fe(0) to remove Cr(VI) during treatment. During initial treatment, Cr(VI) removal rates decreased with time, due to loss of Fe(0) reactivity by mineral fouling. After Fe(0) was passivated, electrochemical depassivation was introduced for different electrolysis times to recover Fe(0) reactivity. It was found that there was approximately 100.4-131.3% initial removal rate recovery, due to the electrochemical break down of precipitates on the Fe(0) surfaces. During the treatment, the decreasing pH and increasing oxidation-reduction Potential (ORP) of the effluent implied the passivation of Fe(0) surfaces. Scanning electron microscope analysis of acid-washed, electrochemically depassivated, and passivated Fe(0) confirmed the efficiency of Elecro-PRB in the recovery Fe(0) reactivity. The results indicate that the Electro-PRB system proposed here is capable of recovering the reactivity of Fe(0), which may prolong the operation of Cr(VI) removal processes."
1509885,Li et al. 2012,One-step synthesis and characterization of core-shell Fe@SiO2 nanocomposite for Cr (VI) reduction,"A facile one-step method was developed to fabricate mono-dispersed Fe nanoparticles (Fe NPs) coated with SiO(2) shell by aqueous reduction method combined with modified Stöber method. Borohydride was acted not only as a reductant for iron salt but also as a catalyst for hydrolysis and polycondensation reaction of tetraethylorthosilicate (TEOS), and more importantly, there was no need to use surface primer for the generation of Fe NPs and catalyst NH(4)OH for SiO(2). Both the Fe NPs agglomeration and SiO(2) shell thickness can be controlled through the synthetic conditions. Lower potassium borohydride (KBH(4)) injection speed was preferable to assemble Fe NPs. The SiO(2) shell thickness increased gradually with the increase of TEOS amount. Under the condition of TEOS amount of 0.1mL and KBH(4) injection speed of 5mL/min, 25nm single Fe NP was coated with SiO(2) shell with thickness of about 9nm. The resulting nanoporous SiO(2) shell was proved to allow reactant to reach the Fe NPs while at the same time protect them from aggregation. The reactivity characterization of the SiO(2)-coated Fe nanoparticles (Fe@SiO(2)) showed that both TEOS concentration and KBH(4) injection speed had effect on Cr (VI) degradation ability. The highest removal capacity of Fe@SiO(2) can reach 467mgCr/gFe at an initial Cr (VI) concentration of 70mg/L under pH 6.0±0.1. XPS and TEM results showed that Cr (VI) was converted to nontoxic Cr (III) and the reaction product was completely adsorbed to SiO(2) shell.","One-step synthesis and characterization of core-shell Fe@SiO2 nanocomposite for Cr (VI) reduction Abs: A facile one-step method was developed to fabricate mono-dispersed Fe nanoparticles (Fe NPs) coated with SiO(2) shell by aqueous reduction method combined with modified Stöber method. Borohydride was acted not only as a reductant for iron salt but also as a catalyst for hydrolysis and polycondensation reaction of tetraethylorthosilicate (TEOS), and more importantly, there was no need to use surface primer for the generation of Fe NPs and catalyst NH(4)OH for SiO(2). Both the Fe NPs agglomeration and SiO(2) shell thickness can be controlled through the synthetic conditions. Lower potassium borohydride (KBH(4)) injection speed was preferable to assemble Fe NPs. The SiO(2) shell thickness increased gradually with the increase of TEOS amount. Under the condition of TEOS amount of 0.1mL and KBH(4) injection speed of 5mL/min, 25nm single Fe NP was coated with SiO(2) shell with thickness of about 9nm. The resulting nanoporous SiO(2) shell was proved to allow reactant to reach the Fe NPs while at the same time protect them from aggregation. The reactivity characterization of the SiO(2)-coated Fe nanoparticles (Fe@SiO(2)) showed that both TEOS concentration and KBH(4) injection speed had effect on Cr (VI) degradation ability. The highest removal capacity of Fe@SiO(2) can reach 467mgCr/gFe at an initial Cr (VI) concentration of 70mg/L under pH 6.0±0.1. XPS and TEM results showed that Cr (VI) was converted to nontoxic Cr (III) and the reaction product was completely adsorbed to SiO(2) shell."
1509884,Kalidhasan et al. 2012,An efficient ultrasound assisted approach for the impregnation of room temperature ionic liquid onto Dowex 1×8 resin matrix and its application toward the enhanced adsorption of chromium (VI),"The work discussed in this paper is based on the utilization of ultrasound in conjunction with an ionic liquid (Aliquat 336) impregnated Dowex 1×8 resin for the effective adsorption of chromium. Ionic liquids are known for their selectivity toward metal extraction and ultrasonic medium offers efficient energy transfer for impregnating the ionic liquid in the resin matrix. The molecular interaction between the ionic liquid impregnated resin and chromium was studied through various physicochemical and spectroscopic techniques. The influence of various analytical parameters on the adsorption of Cr(VI) such as pH, adsorbent dosage, temperature and interference of foreign ions was studied in detail. Chromium (VI) was quantitatively adsorbed in the pH range of 3.5-4, with a high adsorption capacity of 230.9 mg g(-1) in conformity with the Langmuir isotherm model. The study of thermodynamic parameters showed that the adsorption process is exothermic and spontaneous. The adsorbent could be regenerated using 1 mol L(-1) HCl-0.28 mol L(-1) ascorbic acid mixture. Chromium could be effectively detoxified from an industrial effluent and finally the developed method was validated with the analysis of a certified reference material (BCR-715). The obtained results indicated that the ultrasonic assisted impregnation of the room temperature ionic liquid significantly enhances and improves the removal efficiency of Cr(VI).","An efficient ultrasound assisted approach for the impregnation of room temperature ionic liquid onto Dowex 1×8 resin matrix and its application toward the enhanced adsorption of chromium (VI) Abs: The work discussed in this paper is based on the utilization of ultrasound in conjunction with an ionic liquid (Aliquat 336) impregnated Dowex 1×8 resin for the effective adsorption of chromium. Ionic liquids are known for their selectivity toward metal extraction and ultrasonic medium offers efficient energy transfer for impregnating the ionic liquid in the resin matrix. The molecular interaction between the ionic liquid impregnated resin and chromium was studied through various physicochemical and spectroscopic techniques. The influence of various analytical parameters on the adsorption of Cr(VI) such as pH, adsorbent dosage, temperature and interference of foreign ions was studied in detail. Chromium (VI) was quantitatively adsorbed in the pH range of 3.5-4, with a high adsorption capacity of 230.9 mg g(-1) in conformity with the Langmuir isotherm model. The study of thermodynamic parameters showed that the adsorption process is exothermic and spontaneous. The adsorbent could be regenerated using 1 mol L(-1) HCl-0.28 mol L(-1) ascorbic acid mixture. Chromium could be effectively detoxified from an industrial effluent and finally the developed method was validated with the analysis of a certified reference material (BCR-715). The obtained results indicated that the ultrasonic assisted impregnation of the room temperature ionic liquid significantly enhances and improves the removal efficiency of Cr(VI)."
1509883,Naik et al. 2011,Isolation and characterization of Bacillus cereus IST105 from electroplating effluent for detoxification of hexavalent chromium,"<strong>PURPOSE: </strong>Electroplating industries are the main sources of heavy metals, chromium, nickel, lead, zinc, cadmium and copper. The highest concentrations of chromium (VI) in the effluent cause a direct hazards to human and animals. Therefore, there is a need of an effective and affordable biotechnological solution for removal of chromium from electroplating effluent.<br /><br /><strong>METHODS: </strong>Bacterial strains were isolated from electroplating effluent to find out higher tolerant isolate against chromate. The isolate was identified by 16S rDNA sequence analysis. Absorbed chromium level of bacterium was determined by inductively coupled plasma-atomic emission spectrometer (ICP-AES), atomic absorption spectrophotometer (AAS), scanning electron microscope (SEM), transmission electron microscope (TEM) and energy dispersive X-ray analysis (EDX). Removal of metals by bacterium from the electroplating effluent eventually led to the detoxification of effluent confirmed by MTT assay. Conformational changes of functional groups of bacterial cell surface were studied through Fourier transform infrared spectroscopy.<br /><br /><strong>RESULTS: </strong>The chromate tolerant isolate was identified as Bacillus cereus. Bacterium has potency to remove more than 75% of chromium as measured by ICP-AES and AAS. The study indicated the accumulation of chromium (VI) on bacterial cell surface which was confirmed by the SEM-EDX and TEM analysis. The biosorption of metals from the electroplating effluent eventually led to the detoxification of effluent. The increased survivability of Huh7 cells cultured with treated effluent also confirmed the detoxification as examined by MTT assay.<br /><br /><strong>CONCLUSION: </strong>Isolated strain B. cereus was able to remove and detoxify chromium (VI). It would be an efficient tool of the biotechnological approach in mitigating the heavy metal pollutants.","Isolation and characterization of Bacillus cereus IST105 from electroplating effluent for detoxification of hexavalent chromium Abs: <strong>PURPOSE: </strong>Electroplating industries are the main sources of heavy metals, chromium, nickel, lead, zinc, cadmium and copper. The highest concentrations of chromium (VI) in the effluent cause a direct hazards to human and animals. Therefore, there is a need of an effective and affordable biotechnological solution for removal of chromium from electroplating effluent.<br /><br /><strong>METHODS: </strong>Bacterial strains were isolated from electroplating effluent to find out higher tolerant isolate against chromate. The isolate was identified by 16S rDNA sequence analysis. Absorbed chromium level of bacterium was determined by inductively coupled plasma-atomic emission spectrometer (ICP-AES), atomic absorption spectrophotometer (AAS), scanning electron microscope (SEM), transmission electron microscope (TEM) and energy dispersive X-ray analysis (EDX). Removal of metals by bacterium from the electroplating effluent eventually led to the detoxification of effluent confirmed by MTT assay. Conformational changes of functional groups of bacterial cell surface were studied through Fourier transform infrared spectroscopy.<br /><br /><strong>RESULTS: </strong>The chromate tolerant isolate was identified as Bacillus cereus. Bacterium has potency to remove more than 75% of chromium as measured by ICP-AES and AAS. The study indicated the accumulation of chromium (VI) on bacterial cell surface which was confirmed by the SEM-EDX and TEM analysis. The biosorption of metals from the electroplating effluent eventually led to the detoxification of effluent. The increased survivability of Huh7 cells cultured with treated effluent also confirmed the detoxification as examined by MTT assay.<br /><br /><strong>CONCLUSION: </strong>Isolated strain B. cereus was able to remove and detoxify chromium (VI). It would be an efficient tool of the biotechnological approach in mitigating the heavy metal pollutants."
1509882,Rodriguez et al. 2012,Chromium (VI) induces toxicity at different photosynthetic levels in pea,"In order to comprehensively characterize the effects of Cr (VI) on the photosynthetic performance of Pisum sativum, plants irrigated with Cr solutions (ranging from 20 to 2000 mg l(-1)) were evaluated using the following classical endpoints: gas exchange parameters, chlorophyll a (Chl a) fluorescence, leaf pigments, Rubisco activity, soluble sugars and starch content. Flow cytometry (FCM) was applied in an innovative approach to evaluate the morphological and fluorescence emission status of chloroplasts from plants exposed to Cr (VI). The parameters related to gas exchange, net CO(2) assimilation rate (A) and Rubisco activity were severally affected by Cr exposure, in some cases even at the lowest dosage used. While all biomarkers used to measure Chl a fluorescence indicated a decrease in fluorescence at the maximum dosage, pigment contents significantly increased in response to Cr (VI). The morphology of chloroplasts also was altered by Cr (VI) exposure, as a volume decrease was observed. Soluble sugars and starch showed an overall tendency to increase in Cr (VI) exposed plants, but sucrose and glucose decreased highly when exposed to 2000 mg l(-1). In conclusion, our results indicate that Cr (VI) affects photosynthesis at several levels, but the most Cr (VI)-sensitive endpoints were chloroplast morphology and biochemical processes; only at higher dosages the photochemical efficiency is compromised.","Chromium (VI) induces toxicity at different photosynthetic levels in pea Abs: In order to comprehensively characterize the effects of Cr (VI) on the photosynthetic performance of Pisum sativum, plants irrigated with Cr solutions (ranging from 20 to 2000 mg l(-1)) were evaluated using the following classical endpoints: gas exchange parameters, chlorophyll a (Chl a) fluorescence, leaf pigments, Rubisco activity, soluble sugars and starch content. Flow cytometry (FCM) was applied in an innovative approach to evaluate the morphological and fluorescence emission status of chloroplasts from plants exposed to Cr (VI). The parameters related to gas exchange, net CO(2) assimilation rate (A) and Rubisco activity were severally affected by Cr exposure, in some cases even at the lowest dosage used. While all biomarkers used to measure Chl a fluorescence indicated a decrease in fluorescence at the maximum dosage, pigment contents significantly increased in response to Cr (VI). The morphology of chloroplasts also was altered by Cr (VI) exposure, as a volume decrease was observed. Soluble sugars and starch showed an overall tendency to increase in Cr (VI) exposed plants, but sucrose and glucose decreased highly when exposed to 2000 mg l(-1). In conclusion, our results indicate that Cr (VI) affects photosynthesis at several levels, but the most Cr (VI)-sensitive endpoints were chloroplast morphology and biochemical processes; only at higher dosages the photochemical efficiency is compromised."
1509881,Liu et al. 2012,Reutilization of immobilized fungus Rhizopus sp. LG04 to reduce toxic chromate,"<strong>AIMS: </strong>Most of the researches investigating immobilized fungi in chromate [Cr(VI)] bioremediation have used dead cells to adsorb Cr(VI). Therefore, the aim was to identify a Cr(VI)-reducing fungus with the ability of reducing the toxic Cr(VI) into the much less toxic Cr(III) and to apply the immobilized living fungus in continual reduction of Cr(VI).<br /><br /><strong>METHODS AND RESULTS: </strong>Cr(VI) reduction occurred using both free fungi and immobilized living Rhizopus sp. LG04. The Cr(VI) bioreduction by the free fungi was achieved mainly by bioreduction coupled with a small amount of biosorption on the cell surfaces. LG04 spores immobilized with 3% polyvinyl alcohol and 3% sodium alginate produced the most stable and efficient biobeads. When the LG04 biobeads were washed and transferred into fresh medium containing 42 mg l(-1) of Cr(VI), the biobeads could be reused to reduce Cr(VI) for more than 30 cycles during an 82-day operation period. Interestingly, as the cycles increased, the time required for complete reduction stabilized at approximately 2·5 days, which was faster than that obtained using the free fungi (4·5 days). The pH value of the solution decreased from 6·60 ± 0·10 to 3·85 ± 0·15 after each reduction cycle, which may be because the metabolic products of the fungus changed the environmental pH or because there was an accumulation of the organo-Cr(III) complex.<br /><br /><strong>CONCLUSIONS: </strong>The results indicate that using the immobilized living fungus for the removal of Cr(VI) has the advantages in being stable, long-term treatment, easy to re-use and less biomass leakage.<br /><br /><strong>SIGNIFICANCE AND IMPACT OF THE STUDY: </strong>To our knowledge, this study reports the first successful use of immobilized living Rhizopus for the repeated reduction of Cr(VI).","Reutilization of immobilized fungus Rhizopus sp. LG04 to reduce toxic chromate Abs: <strong>AIMS: </strong>Most of the researches investigating immobilized fungi in chromate [Cr(VI)] bioremediation have used dead cells to adsorb Cr(VI). Therefore, the aim was to identify a Cr(VI)-reducing fungus with the ability of reducing the toxic Cr(VI) into the much less toxic Cr(III) and to apply the immobilized living fungus in continual reduction of Cr(VI).<br /><br /><strong>METHODS AND RESULTS: </strong>Cr(VI) reduction occurred using both free fungi and immobilized living Rhizopus sp. LG04. The Cr(VI) bioreduction by the free fungi was achieved mainly by bioreduction coupled with a small amount of biosorption on the cell surfaces. LG04 spores immobilized with 3% polyvinyl alcohol and 3% sodium alginate produced the most stable and efficient biobeads. When the LG04 biobeads were washed and transferred into fresh medium containing 42 mg l(-1) of Cr(VI), the biobeads could be reused to reduce Cr(VI) for more than 30 cycles during an 82-day operation period. Interestingly, as the cycles increased, the time required for complete reduction stabilized at approximately 2·5 days, which was faster than that obtained using the free fungi (4·5 days). The pH value of the solution decreased from 6·60 ± 0·10 to 3·85 ± 0·15 after each reduction cycle, which may be because the metabolic products of the fungus changed the environmental pH or because there was an accumulation of the organo-Cr(III) complex.<br /><br /><strong>CONCLUSIONS: </strong>The results indicate that using the immobilized living fungus for the removal of Cr(VI) has the advantages in being stable, long-term treatment, easy to re-use and less biomass leakage.<br /><br /><strong>SIGNIFICANCE AND IMPACT OF THE STUDY: </strong>To our knowledge, this study reports the first successful use of immobilized living Rhizopus for the repeated reduction of Cr(VI)."
1509880,Quintelas et al. 2011,Optimization of production of extracellular polymeric substances by Arthrobacter viscosus and their interaction with a 13X zeolite for the biosorption of Cr(VI),"In this work we aimed to optimize the production of extracellular polymeric substances (EPS) by an Arthrobacter viscosus biofilm supported on 13X zeolite to be used in the biosorption of Cr(VI). The optimization parameters were agitation rate, work volume, pH and glucose concentration. Following the optimization of EPS production, the biofilm was used in the biosorption of hexavalent Cr from liquid solutions. Differences between the use of dead or active biomass and between the performance of zeolite in powder or in pellet form were also studied. The optimized EPS production allowed values of metal uptake between 2.72 mg/g(biosorbent) and 7.88 mg/g(biosorbent) for initial Cr(VI) concentrations of 20-60 mg/L. For an initial concentration of 20 mg/L, the optimal conditions of EPS production allowed an increase of 10% on the removal percentage of total Cr, and the use of zeolite as a powder rather than the pelleted form produced an increase of 46.5% in the removal percentage. For the initial concentration of 60 mg/L, the use of active biomass compared to dried biomass allowed a reduction of the time required for the total removal of Cr(VI) from 20 to 13 days.","Optimization of production of extracellular polymeric substances by Arthrobacter viscosus and their interaction with a 13X zeolite for the biosorption of Cr(VI) Abs: In this work we aimed to optimize the production of extracellular polymeric substances (EPS) by an Arthrobacter viscosus biofilm supported on 13X zeolite to be used in the biosorption of Cr(VI). The optimization parameters were agitation rate, work volume, pH and glucose concentration. Following the optimization of EPS production, the biofilm was used in the biosorption of hexavalent Cr from liquid solutions. Differences between the use of dead or active biomass and between the performance of zeolite in powder or in pellet form were also studied. The optimized EPS production allowed values of metal uptake between 2.72 mg/g(biosorbent) and 7.88 mg/g(biosorbent) for initial Cr(VI) concentrations of 20-60 mg/L. For an initial concentration of 20 mg/L, the optimal conditions of EPS production allowed an increase of 10% on the removal percentage of total Cr, and the use of zeolite as a powder rather than the pelleted form produced an increase of 46.5% in the removal percentage. For the initial concentration of 60 mg/L, the use of active biomass compared to dried biomass allowed a reduction of the time required for the total removal of Cr(VI) from 20 to 13 days."
1509879,Chahal et al. 2012,Preconcentration method on modified silica fiber for chromium speciation,"A new method involving pre-concentration on modified silica fiber is described for the speciation of chromium(III) [Cr(III)] and chromium(VI) [Cr(VI)] in aqueous media. This method is based on the different chelating behavior of Cr(III) and Cr(VI) with morpholine-4-carbodithioate (MDTC). Both complexes are extracted on silica fiber modified by sol-gel technology by using 3-aminopropyltriethoxysilane (APS) as a precursor. All extracted samples are directly injected into an high-performance liquid chromatography injector for the simultaneous determination of Cr(III) and Cr(VI). Cr(VI) forms two different complexes, and Cr(III) forms a single complex with MDTC. Therefore, the concentration of Cr(VI) is determined directly from the peak area obtained at 5.4 min; whereas, the assay of Cr(III) is based on subtracting the peak area of Cr(VI) from the total peak area obtained at 4.3 min. Under the optimized conditions, the limits of detection for Cr(III) and Cr(VI) are found to be 0.7 ng/mL and 0.2 ng/mL, respectively.","Preconcentration method on modified silica fiber for chromium speciation Abs: A new method involving pre-concentration on modified silica fiber is described for the speciation of chromium(III) [Cr(III)] and chromium(VI) [Cr(VI)] in aqueous media. This method is based on the different chelating behavior of Cr(III) and Cr(VI) with morpholine-4-carbodithioate (MDTC). Both complexes are extracted on silica fiber modified by sol-gel technology by using 3-aminopropyltriethoxysilane (APS) as a precursor. All extracted samples are directly injected into an high-performance liquid chromatography injector for the simultaneous determination of Cr(III) and Cr(VI). Cr(VI) forms two different complexes, and Cr(III) forms a single complex with MDTC. Therefore, the concentration of Cr(VI) is determined directly from the peak area obtained at 5.4 min; whereas, the assay of Cr(III) is based on subtracting the peak area of Cr(VI) from the total peak area obtained at 4.3 min. Under the optimized conditions, the limits of detection for Cr(III) and Cr(VI) are found to be 0.7 ng/mL and 0.2 ng/mL, respectively."
1509878,Han et al. 2012,Differential isotopic fractionation during Cr(VI) reduction by an aquifer-derived bacterium under aerobic versus denitrifying conditions,"We studied Cr isotopic fractionation during Cr(VI) reduction by Pseudomonas stutzeri strain RCH2. Despite the fact that strain RCH2 reduces Cr(VI) cometabolically under both aerobic and denitrifying conditions and at similar specific rates, fractionation was markedly different under these two conditions (? was ?2‰ aerobically and ?0.4‰ under denitrifying conditions).","Differential isotopic fractionation during Cr(VI) reduction by an aquifer-derived bacterium under aerobic versus denitrifying conditions Abs: We studied Cr isotopic fractionation during Cr(VI) reduction by Pseudomonas stutzeri strain RCH2. Despite the fact that strain RCH2 reduces Cr(VI) cometabolically under both aerobic and denitrifying conditions and at similar specific rates, fractionation was markedly different under these two conditions (? was ?2‰ aerobically and ?0.4‰ under denitrifying conditions)."
1509877,Ilias et al. 2011,Isolation and Characterization of Chromium(VI)-Reducing Bacteria from Tannery Effluents,"Two chromium-resistant bacteria (IFR-2 and IFR-3) capable of reducing/transforming Cr(VI) to Cr(III) were isolated from tannery effluents. Isolates IFR-2 and IFR-3 were identified as Staphylococcus aureus and Pediococcus pentosaceus respectively by 16S rRNA gene sequence analyses. Both isolates can grow well on 2,000 mg/l Cr(VI) (as K(2)Cr(2)O(7)) in Luria-Bertani (LB) medium. Reduction of Cr(VI) was found to be growth-associated in both isolates and IFR-2 and IFR-3 reduced 20 mg/l Cr(VI) completely in 6 and 24 h respectively. The Cr(VI) reduction due to chromate reductase activity was detected in the culture supernatant and cell lysate but not at all in the cell extract supernatant of both isolates. Whole cells of IFR-2 and IFR-3 converted 24 and 30% of the initial Cr(VI) concentration (1 mg/l) in 45 min respectively at 37°C. NiCl(2) stimulated the growth of IFR-2 whereas HgCl(2) and CdCl(2) significantly inhibited the growth of both isolates. Optimum temperature and pH for growth of and Cr(VI) reduction by both isolates were found to be between 35 and 40°C and pH 7.0 to 8.0. The two bacterial isolates can be good candidates for detoxification of Cr(VI) in industrial effluents.","Isolation and Characterization of Chromium(VI)-Reducing Bacteria from Tannery Effluents Abs: Two chromium-resistant bacteria (IFR-2 and IFR-3) capable of reducing/transforming Cr(VI) to Cr(III) were isolated from tannery effluents. Isolates IFR-2 and IFR-3 were identified as Staphylococcus aureus and Pediococcus pentosaceus respectively by 16S rRNA gene sequence analyses. Both isolates can grow well on 2,000 mg/l Cr(VI) (as K(2)Cr(2)O(7)) in Luria-Bertani (LB) medium. Reduction of Cr(VI) was found to be growth-associated in both isolates and IFR-2 and IFR-3 reduced 20 mg/l Cr(VI) completely in 6 and 24 h respectively. The Cr(VI) reduction due to chromate reductase activity was detected in the culture supernatant and cell lysate but not at all in the cell extract supernatant of both isolates. Whole cells of IFR-2 and IFR-3 converted 24 and 30% of the initial Cr(VI) concentration (1 mg/l) in 45 min respectively at 37°C. NiCl(2) stimulated the growth of IFR-2 whereas HgCl(2) and CdCl(2) significantly inhibited the growth of both isolates. Optimum temperature and pH for growth of and Cr(VI) reduction by both isolates were found to be between 35 and 40°C and pH 7.0 to 8.0. The two bacterial isolates can be good candidates for detoxification of Cr(VI) in industrial effluents."
1509876,Tripathi et al. 2011,Isolation and Growth Characteristics of Chromium(VI) and Pentachlorophenol Tolerant Bacterial Isolate from Treated Tannery Effluent for its Possible Use in Simultaneous Bioremediation,"The bacterial strains resistant to pentachlorophenol (PCP) and hexavalent chromium [Cr(VI)] were isolated from treated tannery effluent of a common effluent treatment plant. Most of the physico-chemical parameters analyzed were above permissible limits. Thirty-eight and four bacterial isolates, respectively were found resistant to &gt;50 ?g/ml concentration of [Cr(VI)] and the same level of PCP. Out of the above 42 isolates, only one was found simultaneously tolerant to higher levels of both PCP (500 ?g/ml) and Cr(VI) (200 ?g/ml), and hence was selected for further studies. To the best of our knowledge, this is the first report in which a native bacterial isolate simultaneously tolerant to such a high concentrations of Cr(VI) and PCP has been reported. The culture growth was best at 0.4% (w/v) glucose as an additional carbon source and 0.2% (w/v) ammonium chloride as a nitrogen source. The growth results with cow urine as a nitrogen source were comparable with the best nitrogen source ammonium chloride. The isolate exhibited resistance to multiple heavy metals (Pb, As, Hg, Zn, Co &amp; Ni) and to antibiotics nalidixic acid and polymixin-B. The efficacy of bacterial isolate for growth, PCP degradation (56.5%) and Cr(VI) bioremediation (74.5%) was best at 48 h incubation. The isolate was identified as Bacillus sp. by morphological and biochemical tests. The 16S rDNA sequence analysis revealed 98% homology with Bacillus cereus. However, further molecular analysis is underway to ascertain its likelyhood of a novel species.","Isolation and Growth Characteristics of Chromium(VI) and Pentachlorophenol Tolerant Bacterial Isolate from Treated Tannery Effluent for its Possible Use in Simultaneous Bioremediation Abs: The bacterial strains resistant to pentachlorophenol (PCP) and hexavalent chromium [Cr(VI)] were isolated from treated tannery effluent of a common effluent treatment plant. Most of the physico-chemical parameters analyzed were above permissible limits. Thirty-eight and four bacterial isolates, respectively were found resistant to &gt;50 ?g/ml concentration of [Cr(VI)] and the same level of PCP. Out of the above 42 isolates, only one was found simultaneously tolerant to higher levels of both PCP (500 ?g/ml) and Cr(VI) (200 ?g/ml), and hence was selected for further studies. To the best of our knowledge, this is the first report in which a native bacterial isolate simultaneously tolerant to such a high concentrations of Cr(VI) and PCP has been reported. The culture growth was best at 0.4% (w/v) glucose as an additional carbon source and 0.2% (w/v) ammonium chloride as a nitrogen source. The growth results with cow urine as a nitrogen source were comparable with the best nitrogen source ammonium chloride. The isolate exhibited resistance to multiple heavy metals (Pb, As, Hg, Zn, Co &amp; Ni) and to antibiotics nalidixic acid and polymixin-B. The efficacy of bacterial isolate for growth, PCP degradation (56.5%) and Cr(VI) bioremediation (74.5%) was best at 48 h incubation. The isolate was identified as Bacillus sp. by morphological and biochemical tests. The 16S rDNA sequence analysis revealed 98% homology with Bacillus cereus. However, further molecular analysis is underway to ascertain its likelyhood of a novel species."
1509875,Baikousi et al. 2012,Synthesis and characterization of ?-Fe2O3/carbon hybrids and their application in removal of hexavalent chromium ions from aqueous solutions,"Magnetic Fe(2)O(3)/carbon hybrids were prepared in a two-step process. First, acetic acid vapor interacted with iron cations dispersed on the surface of a nanocasted ordered mesoporous carbon (CMK-3). In the second step, the primarily created iron acetate species underwent pyrolysis and transformed to magnetic iron oxide nanoparticles. X-ray diffraction, Fourier-transform infrared, and Raman spectroscopies were used for the chemical and structural characterization of the hybrids, while surface area measurements, thermal analysis, and transmission electron microscopy were employed to determine their physical, surface, and textural properties. These results revealed the preservation of the host carbon structure, which was homogenously and controllably loaded (up to 27 wt %) with nanosized (ca. 20 nm) iron oxides inside the mesoporous system. Mössbauer spectroscopy and magnetic measurements at low temperatures confirmed the formation of ?-Fe(2)O(3) nanoparticles exhibiting superparamagnetic behavior. The kinetic studies showed a rapid removal of Cr(VI) ions from the aqueous solutions in the presence of these magnetic mesoporous hybrids and a considerably increased adsorption capacity per unit mass of sorbent in comparison to that of pristine CMK-3 carbon. The results also indicate highly pH-dependent sorption efficiency of the hybrids, whereas their kinetics was described by a pseudo-second-order kinetic model. Taking into account the simplicity of the synthetic procedure and possibility of magnetic separation of hybrids with immobilized pollutant, the developed mesoporous nanomaterials have quite real potential for applications in water treatment technologies.","Synthesis and characterization of ?-Fe2O3/carbon hybrids and their application in removal of hexavalent chromium ions from aqueous solutions Abs: Magnetic Fe(2)O(3)/carbon hybrids were prepared in a two-step process. First, acetic acid vapor interacted with iron cations dispersed on the surface of a nanocasted ordered mesoporous carbon (CMK-3). In the second step, the primarily created iron acetate species underwent pyrolysis and transformed to magnetic iron oxide nanoparticles. X-ray diffraction, Fourier-transform infrared, and Raman spectroscopies were used for the chemical and structural characterization of the hybrids, while surface area measurements, thermal analysis, and transmission electron microscopy were employed to determine their physical, surface, and textural properties. These results revealed the preservation of the host carbon structure, which was homogenously and controllably loaded (up to 27 wt %) with nanosized (ca. 20 nm) iron oxides inside the mesoporous system. Mössbauer spectroscopy and magnetic measurements at low temperatures confirmed the formation of ?-Fe(2)O(3) nanoparticles exhibiting superparamagnetic behavior. The kinetic studies showed a rapid removal of Cr(VI) ions from the aqueous solutions in the presence of these magnetic mesoporous hybrids and a considerably increased adsorption capacity per unit mass of sorbent in comparison to that of pristine CMK-3 carbon. The results also indicate highly pH-dependent sorption efficiency of the hybrids, whereas their kinetics was described by a pseudo-second-order kinetic model. Taking into account the simplicity of the synthetic procedure and possibility of magnetic separation of hybrids with immobilized pollutant, the developed mesoporous nanomaterials have quite real potential for applications in water treatment technologies."
1509874,Hotta et al. 2012,"Determination of chromium(III), chromium(VI) and total chromium in chromate and trivalent chromium conversion coatings by electrospray ionization mass spectrometry","Developed were the determination methods of Cr(VI) and Cr(III) by electrospray ionization mass spectrometry, where HCrO(4)(-) (m/z 117) and [Cr(III)(cydta)](-) (m/z 394) were measured, respectively. Moreover, total Cr was also determined by measuring [Cr(III)(cydta)](-) after reduction of Cr(VI) with ascorbic acid. Here, cydta denotes trans-1,2-diaminocyclohexane-N,N,N',N'-tetraacetic acid. The detection limits were ca. 13 nmol/dm(3) for Cr(VI) and 56 nmol/dm(3) for Cr(III) and total Cr. The proposed methods were applied to analyze chromate and trivalent chromium conversion coatings and gave consistent results with those obtained by a diphenylcarbazide spectrophotometric method for Cr(VI) and ICP-AES for total Cr.","Determination of chromium(III), chromium(VI) and total chromium in chromate and trivalent chromium conversion coatings by electrospray ionization mass spectrometry Abs: Developed were the determination methods of Cr(VI) and Cr(III) by electrospray ionization mass spectrometry, where HCrO(4)(-) (m/z 117) and [Cr(III)(cydta)](-) (m/z 394) were measured, respectively. Moreover, total Cr was also determined by measuring [Cr(III)(cydta)](-) after reduction of Cr(VI) with ascorbic acid. Here, cydta denotes trans-1,2-diaminocyclohexane-N,N,N',N'-tetraacetic acid. The detection limits were ca. 13 nmol/dm(3) for Cr(VI) and 56 nmol/dm(3) for Cr(III) and total Cr. The proposed methods were applied to analyze chromate and trivalent chromium conversion coatings and gave consistent results with those obtained by a diphenylcarbazide spectrophotometric method for Cr(VI) and ICP-AES for total Cr."
1509873,San and  Dönmez 2012,"Biosorption of chromium(VI), nickel(II) and Remazol blue by Rhodotorula muciloginosa biomass","The passive removal of commonly used reactive dye and two heavy metals, from aqueous solutions by inexpensive biomaterial, yeast Rhodotorula muciloginosa biomass, termed biosorption, was studied with respect to pH, initial dye concentration and initial metal ion concentration. The biomass exhibited maximum dye and chromium(VI) uptake at pH 5 and pH 6 for nickel(II) in media containing 50 mg/L heavy metal and 50 mg/L remazol blue. It was found that the highest chromium(VI) removal yields measured were 31.3% for 49.0 mg/l initial chromium(VI) concentrations. The nickel(II) removal yield was 32.5% for 22.3 mg/L. Higher R. Blue removal yields were obtained, such as 77.1% for 117.5 mg/L. The maximum dye biosorption yield was investigated in medium with a constant dye (approximately 50 mg/L) and increasing heavy metal concentration. In the medium with 48.8, 103.8 and 151.8 mg/L chromium(VI) and constant dye concentration, the maximum chromium(VI) biosorption was 7.4, 9.3 and 17.1%, whereas the maximum dye biosorption was 61.6, 56.6 and 55.9%. The maximum nickel(II) biosorptions in the medium with dye were 38.1, 22.1 and 8.8% at 23.7, 37.7 and 60.1 mg/L nickel(II) concentrations. In these media, dye biosorptions were 93.9, 86.4 and 93.3%, respectively.","Biosorption of chromium(VI), nickel(II) and Remazol blue by Rhodotorula muciloginosa biomass Abs: The passive removal of commonly used reactive dye and two heavy metals, from aqueous solutions by inexpensive biomaterial, yeast Rhodotorula muciloginosa biomass, termed biosorption, was studied with respect to pH, initial dye concentration and initial metal ion concentration. The biomass exhibited maximum dye and chromium(VI) uptake at pH 5 and pH 6 for nickel(II) in media containing 50 mg/L heavy metal and 50 mg/L remazol blue. It was found that the highest chromium(VI) removal yields measured were 31.3% for 49.0 mg/l initial chromium(VI) concentrations. The nickel(II) removal yield was 32.5% for 22.3 mg/L. Higher R. Blue removal yields were obtained, such as 77.1% for 117.5 mg/L. The maximum dye biosorption yield was investigated in medium with a constant dye (approximately 50 mg/L) and increasing heavy metal concentration. In the medium with 48.8, 103.8 and 151.8 mg/L chromium(VI) and constant dye concentration, the maximum chromium(VI) biosorption was 7.4, 9.3 and 17.1%, whereas the maximum dye biosorption was 61.6, 56.6 and 55.9%. The maximum nickel(II) biosorptions in the medium with dye were 38.1, 22.1 and 8.8% at 23.7, 37.7 and 60.1 mg/L nickel(II) concentrations. In these media, dye biosorptions were 93.9, 86.4 and 93.3%, respectively."
1509872,Katsaveli et al. 2012,Bacterial diversity in Cr(VI) and Cr(III)-contaminated industrial wastewaters,"The bacterial community structure of a chromium water bath, a chromium drainage waste system, a chromium pretreatment tank, and a trivalent chromium precipitation tank from the Hellenic Aerospace Industry S.A. was assessed using 16S rRNA libraries and a high-density DNA microarray (PhyloChip). 16S rRNA libraries revealed a bacterial diversity consisting of 14 distinct operational taxonomic units belonging to five bacterial phyla: Alphaproteobacteria, Betaproteobacteria, Gammaproteobacteria, Actinobacteria, and Bacteroidetes. However, employing a novel microarray-based approach (PhyloChip), a high bacterial diversity consisting of 30 different phyla was revealed, with representatives of 181 different families. This made it possible to identify a core set of genera present in all wastewater treatment stages examined, consisting of members of Alphaproteobacteria, Betaproteobacteria, Gammaproteobacteria, Deltaproteobacteria, Epsilonproteobacteria, and Bacteroidetes. In the chromium pretreatment tank, where the concentration of Cr(VI) is high (2.3 mg/l), we identified the presence of Pseudomonadales, Actinomycetales, and Enterobacteriales in abundance. In the chromium precipitation tank, where the concentration of Cr(III) is high, the dominant bacteria consortia were replaced by members of Rhodocyclales and Chloroflexi. The bacterial community structure changed significantly with changes in the chromium concentration. This in-depth analysis should prove useful for the design and development of improved bioremediation strategies.","Bacterial diversity in Cr(VI) and Cr(III)-contaminated industrial wastewaters Abs: The bacterial community structure of a chromium water bath, a chromium drainage waste system, a chromium pretreatment tank, and a trivalent chromium precipitation tank from the Hellenic Aerospace Industry S.A. was assessed using 16S rRNA libraries and a high-density DNA microarray (PhyloChip). 16S rRNA libraries revealed a bacterial diversity consisting of 14 distinct operational taxonomic units belonging to five bacterial phyla: Alphaproteobacteria, Betaproteobacteria, Gammaproteobacteria, Actinobacteria, and Bacteroidetes. However, employing a novel microarray-based approach (PhyloChip), a high bacterial diversity consisting of 30 different phyla was revealed, with representatives of 181 different families. This made it possible to identify a core set of genera present in all wastewater treatment stages examined, consisting of members of Alphaproteobacteria, Betaproteobacteria, Gammaproteobacteria, Deltaproteobacteria, Epsilonproteobacteria, and Bacteroidetes. In the chromium pretreatment tank, where the concentration of Cr(VI) is high (2.3 mg/l), we identified the presence of Pseudomonadales, Actinomycetales, and Enterobacteriales in abundance. In the chromium precipitation tank, where the concentration of Cr(III) is high, the dominant bacteria consortia were replaced by members of Rhodocyclales and Chloroflexi. The bacterial community structure changed significantly with changes in the chromium concentration. This in-depth analysis should prove useful for the design and development of improved bioremediation strategies."
1509871,Shukla and  Vankar 2012,Efficient biosorption of chromium(VI) ion by dry Araucaria leaves,"<strong>BACKGROUND: </strong>In this paper, batch removal of hexavalent chromium from aqueous solutions by Araucaria heterophylla leaves was investigated. The batch experiments were conducted to study the adsorption of metal species and effect of different pH, contact time, metal concentration, biosorbent concentration, and adsorption capacity.<br /><br /><strong>METHOD: </strong>Freundlich and Langmuir's isotherm model were used to describe the adsorption behavior, and the experimental results fitted Freundlich model well.<br /><br /><strong>RESULTS: </strong>The adsorption efficiency observed for all chromium concentrations, i.e., 1, 3, 5, and 10 mg/L was 100% and the equilibrium was achieved in 30 min for 1 and 3 mg/L, whereas for 5 and 10 mg/L, it was less than 60 min. FTIR spectra was taken to identify functional groups involved in the biosorption.<br /><br /><strong>CONCLUSION: </strong>Thus, Araucaria leaves can be considered as one of the cheap and efficient biosorbent for toxic hexavalent chromium removal from natural or wastewaters.","Efficient biosorption of chromium(VI) ion by dry Araucaria leaves Abs: <strong>BACKGROUND: </strong>In this paper, batch removal of hexavalent chromium from aqueous solutions by Araucaria heterophylla leaves was investigated. The batch experiments were conducted to study the adsorption of metal species and effect of different pH, contact time, metal concentration, biosorbent concentration, and adsorption capacity.<br /><br /><strong>METHOD: </strong>Freundlich and Langmuir's isotherm model were used to describe the adsorption behavior, and the experimental results fitted Freundlich model well.<br /><br /><strong>RESULTS: </strong>The adsorption efficiency observed for all chromium concentrations, i.e., 1, 3, 5, and 10 mg/L was 100% and the equilibrium was achieved in 30 min for 1 and 3 mg/L, whereas for 5 and 10 mg/L, it was less than 60 min. FTIR spectra was taken to identify functional groups involved in the biosorption.<br /><br /><strong>CONCLUSION: </strong>Thus, Araucaria leaves can be considered as one of the cheap and efficient biosorbent for toxic hexavalent chromium removal from natural or wastewaters."
1509870,Fonseca et al. 2012,Removal of hexavalent chromium of contaminated soil by coupling electrokinetic remediation and permeable reactive biobarriers,"<strong>PURPOSE: </strong>In this study, a novel and ecological alternative have been developed to treat soils contaminated with hexavalent chromium coupling two well-known systems: electrokinetic remediation and permeable reactive biobarriers. The electric field promotes the electromigration of the hexavalent chromium oxyanions towards the anode. The biobarriers were placed before the anode electrode, in order to promote the reduction and retention of the chromium migrating in its direction. Thus, this technology provided a global treatment to soil removal without subsequent treatments of the contaminated effluents.<br /><br /><strong>METHODS: </strong>The electrokinetic system was coupled with two different permeable reactive biobarriers composed by Arthrobacter viscosus bacteria, supported either in activated carbon or zeolite. An electric field of 10 V was applied and two different treatment times of 9 and 18 days were tested.<br /><br /><strong>RESULTS: </strong>Removal values of 60% and 79% were obtained when electrokinetic treatment was coupled with zeolite and activated carbon biobarriers, respectively, for a test period of 18 day. The reduction of hexavalent chromium to trivalent chromium was around 45% for both systems.<br /><br /><strong>CONCLUSIONS: </strong>In this work, two types of biobarriers were efficiently coupled to electrokinetic treatment to decontaminate soil with Cr(VI). Furthermore, the viability of the new coupling technology developed (electrokinetic + biobarriers) to treat low-permeability polluted soils was demonstrated.","Removal of hexavalent chromium of contaminated soil by coupling electrokinetic remediation and permeable reactive biobarriers Abs: <strong>PURPOSE: </strong>In this study, a novel and ecological alternative have been developed to treat soils contaminated with hexavalent chromium coupling two well-known systems: electrokinetic remediation and permeable reactive biobarriers. The electric field promotes the electromigration of the hexavalent chromium oxyanions towards the anode. The biobarriers were placed before the anode electrode, in order to promote the reduction and retention of the chromium migrating in its direction. Thus, this technology provided a global treatment to soil removal without subsequent treatments of the contaminated effluents.<br /><br /><strong>METHODS: </strong>The electrokinetic system was coupled with two different permeable reactive biobarriers composed by Arthrobacter viscosus bacteria, supported either in activated carbon or zeolite. An electric field of 10 V was applied and two different treatment times of 9 and 18 days were tested.<br /><br /><strong>RESULTS: </strong>Removal values of 60% and 79% were obtained when electrokinetic treatment was coupled with zeolite and activated carbon biobarriers, respectively, for a test period of 18 day. The reduction of hexavalent chromium to trivalent chromium was around 45% for both systems.<br /><br /><strong>CONCLUSIONS: </strong>In this work, two types of biobarriers were efficiently coupled to electrokinetic treatment to decontaminate soil with Cr(VI). Furthermore, the viability of the new coupling technology developed (electrokinetic + biobarriers) to treat low-permeability polluted soils was demonstrated."
1509869,Sugiyama et al. 2012,Hexavalent chromium reduction by an actinobacterium Flexivirga alba ST13T in the family Dermacoccaceae,"An isolated strain Flexivirga alba ST13(T) was examined for the reducing activity of hexavalent chromium (Cr(VI)). Strain ST13(T) grew in the liquid medium containing 0.33 mM Cr(VI) under aerobic cultivation, even though growth was inhibited on agar minimal media containing 0.31 mM Cr(VI). The growth in the liquid medium containing Cr(VI) at 3 mM was severely inhibited, and the concentration of Cr(VI) decreased below the detection limit within 13 days. Most of the Cr(VI) was eliminated from the liquid medium in the log phase and the stationary phase. XANES analysis of the precipitate shows the presence of Cr(OH)(3), indicating the bacterial reduction of Cr(VI) to trivalent chromium (Cr(III)). The bacterial Cr(VI) reduction was more efficient in minimal medium supplemented with molasses than with glucose. These results strongly suggest that the isolate F. alba ST13(T) is a novel actinobacterium with Cr(VI) reducing activity that is stimulated by molasses.","Hexavalent chromium reduction by an actinobacterium Flexivirga alba ST13T in the family Dermacoccaceae Abs: An isolated strain Flexivirga alba ST13(T) was examined for the reducing activity of hexavalent chromium (Cr(VI)). Strain ST13(T) grew in the liquid medium containing 0.33 mM Cr(VI) under aerobic cultivation, even though growth was inhibited on agar minimal media containing 0.31 mM Cr(VI). The growth in the liquid medium containing Cr(VI) at 3 mM was severely inhibited, and the concentration of Cr(VI) decreased below the detection limit within 13 days. Most of the Cr(VI) was eliminated from the liquid medium in the log phase and the stationary phase. XANES analysis of the precipitate shows the presence of Cr(OH)(3), indicating the bacterial reduction of Cr(VI) to trivalent chromium (Cr(III)). The bacterial Cr(VI) reduction was more efficient in minimal medium supplemented with molasses than with glucose. These results strongly suggest that the isolate F. alba ST13(T) is a novel actinobacterium with Cr(VI) reducing activity that is stimulated by molasses."
1509868,Parker et al. 2011,The Response of Shewanella oneidensis MR-1 to Cr(III) Toxicity Differs from that to Cr(VI),"Chromium is a contaminant of concern that is found in drinking water in its soluble, hexavalent form [Cr(VI)] and that is known to be toxic to eukaryotes and prokaryotes. Trivalent chromium [Cr(III)] is thought to be largely harmless due to its low solubility and inability to enter cells. Previous work has suggested that Cr(III) may also be toxic to microorganisms but the mechanism remained elusive. In this work, we probe the toxicity of Cr(III) to Shewanella oneidensis MR-1, a bacterium able to reduce Cr(VI) to Cr(III) and compare it to Cr(VI) toxicity. We found evidence for Cr(III) toxicity both under Cr(VI) reducing conditions, during which Cr(III) was generated by the reduction process, and under non-reducing conditions, when Cr(III) was amended exogenously. Interestingly, cells exposed to Cr(III) (200??M) experienced rapid viability loss as measured by colony forming units on Luria-Bertani (LB) agar plates. In contrast, they maintained some enzymatic activity and cellular integrity. Cr(VI)-exposed cells exhibited loss of enzymatic activity and cell lysis. The loss of viability of Cr(III)-exposed cells was not due to membrane damage or to enzymatic inhibition but rather appeared to be associated with an abnormal morphology that consisted of chains of membrane-enclosed units of irregular size. Exposure of abnormal cells to growth conditions resulted in membrane damage and cell death, which is consistent with the observed viability loss on LB plates. While Cr(VI) was taken up intracellularly and caused cell lysis, the toxic effect of Cr(III) appeared to be associated with extracellular interactions leading to an ultimately lethal cell morphology.","The Response of Shewanella oneidensis MR-1 to Cr(III) Toxicity Differs from that to Cr(VI) Abs: Chromium is a contaminant of concern that is found in drinking water in its soluble, hexavalent form [Cr(VI)] and that is known to be toxic to eukaryotes and prokaryotes. Trivalent chromium [Cr(III)] is thought to be largely harmless due to its low solubility and inability to enter cells. Previous work has suggested that Cr(III) may also be toxic to microorganisms but the mechanism remained elusive. In this work, we probe the toxicity of Cr(III) to Shewanella oneidensis MR-1, a bacterium able to reduce Cr(VI) to Cr(III) and compare it to Cr(VI) toxicity. We found evidence for Cr(III) toxicity both under Cr(VI) reducing conditions, during which Cr(III) was generated by the reduction process, and under non-reducing conditions, when Cr(III) was amended exogenously. Interestingly, cells exposed to Cr(III) (200??M) experienced rapid viability loss as measured by colony forming units on Luria-Bertani (LB) agar plates. In contrast, they maintained some enzymatic activity and cellular integrity. Cr(VI)-exposed cells exhibited loss of enzymatic activity and cell lysis. The loss of viability of Cr(III)-exposed cells was not due to membrane damage or to enzymatic inhibition but rather appeared to be associated with an abnormal morphology that consisted of chains of membrane-enclosed units of irregular size. Exposure of abnormal cells to growth conditions resulted in membrane damage and cell death, which is consistent with the observed viability loss on LB plates. While Cr(VI) was taken up intracellularly and caused cell lysis, the toxic effect of Cr(III) appeared to be associated with extracellular interactions leading to an ultimately lethal cell morphology."
1509867,Zhang et al. 2012,Ionothermal synthesis of hierarchical BiOBr microspheres for water treatment,"Bismuth oxybromide (BiOBr) micropsheres with hierarchical morphologies have been fabricated via an ionothermal synthesis route. Ionic liquid acts as a unique soft material capable of promoting nucleation and in situ growth of 3D hierarchical BiOBr mesocrystals without the help of surfactants. The as-prepared BiOBr nanomaterials can effectively remove heavy metal ions and organic dyes from wastewater. They can also kill Micrococcus lylae, a Gram positive bacterium, in water under fluorescent light irradiation. Their high adaptability in water treatment may be ascribed to their hierarchical structure, allowing them high surface to volume ratio, facile species transportation and excellent light-harvesting ability.","Ionothermal synthesis of hierarchical BiOBr microspheres for water treatment Abs: Bismuth oxybromide (BiOBr) micropsheres with hierarchical morphologies have been fabricated via an ionothermal synthesis route. Ionic liquid acts as a unique soft material capable of promoting nucleation and in situ growth of 3D hierarchical BiOBr mesocrystals without the help of surfactants. The as-prepared BiOBr nanomaterials can effectively remove heavy metal ions and organic dyes from wastewater. They can also kill Micrococcus lylae, a Gram positive bacterium, in water under fluorescent light irradiation. Their high adaptability in water treatment may be ascribed to their hierarchical structure, allowing them high surface to volume ratio, facile species transportation and excellent light-harvesting ability."
1509866,Kalidhasan et al. 2012,Ultrasound-assisted preparation and characterization of crystalline cellulose-ionic liquid blend polymeric material: a prelude to the study of its application toward the effective adsorption of chromium,"The molecular interaction of biopolymers with an array of substrates offers interesting insight into the adsorption phenomenon. The present work proposes the preparation and characterization of cellulose-methyltrioctylammonium chloride (MeTOACl)-a room temperature ionic liquid (IL) blend polymeric sorbent and its application for the adsorption of carcinogenic chromium(VI). The blend adsorbent material was synthesized in a relatively green solvent (methylisobutylketone) medium by ultrasonication. The mechanism of interaction of biopolymer with the ionic liquid could be conceptualized as electrostatic attraction, hydrogen bonding, and Van der Waals force of attraction with the hydroxyl groups of cellulose as a bilayer assembly. The composition, crystallinity, and the surface area of the prepared material were comprehensively characterized using FT-IR, solid-state (13)C NMR, TGA, XRD, SEM, EDX, XPS, and BET isotherm study. The adsorption capacity of chromium(VI) calculated from Langmuir isotherm model was found to be 38.94 mg g(-1) with adherence to the second-order kinetics. The study of thermodynamic parameters that affect the sorption process indicated the spontaneity and exothermic nature of adsorption. The green aspect in the methodology is brought out in the regeneration of the adsorbent, where Cr(VI) could be effectively reduced to the less toxic Cr(III) using ascorbic acid.","Ultrasound-assisted preparation and characterization of crystalline cellulose-ionic liquid blend polymeric material: a prelude to the study of its application toward the effective adsorption of chromium Abs: The molecular interaction of biopolymers with an array of substrates offers interesting insight into the adsorption phenomenon. The present work proposes the preparation and characterization of cellulose-methyltrioctylammonium chloride (MeTOACl)-a room temperature ionic liquid (IL) blend polymeric sorbent and its application for the adsorption of carcinogenic chromium(VI). The blend adsorbent material was synthesized in a relatively green solvent (methylisobutylketone) medium by ultrasonication. The mechanism of interaction of biopolymer with the ionic liquid could be conceptualized as electrostatic attraction, hydrogen bonding, and Van der Waals force of attraction with the hydroxyl groups of cellulose as a bilayer assembly. The composition, crystallinity, and the surface area of the prepared material were comprehensively characterized using FT-IR, solid-state (13)C NMR, TGA, XRD, SEM, EDX, XPS, and BET isotherm study. The adsorption capacity of chromium(VI) calculated from Langmuir isotherm model was found to be 38.94 mg g(-1) with adherence to the second-order kinetics. The study of thermodynamic parameters that affect the sorption process indicated the spontaneity and exothermic nature of adsorption. The green aspect in the methodology is brought out in the regeneration of the adsorbent, where Cr(VI) could be effectively reduced to the less toxic Cr(III) using ascorbic acid."
1509865,Yonar et al. ,Antioxidant effect of propolis against exposure to chromium in Cyprinus carpio,"The aim of the present study was to investigate the ameliorative properties of propolis against the toxic effects of chromium (VI) by examining oxidative damage markers such as lipid peroxidation and the antioxidant defence system components in carp (Cyprinus carpio). The fish were exposed to sublethal concentrations of chromium. Propolis was simultaneously administered to chromium-exposed fish. Treatment was continued for 28 days, and at the end of this period, blood and tissue (liver, kidney, spleen, and gill) samples were collected. Levels of malondialdehyde (MDA) and reduced glutathione (GSH) as well as superoxide dismutase (SOD), catalase (CAT), and glutathione peroxidase (GSH-Px) activities were determined in blood and tissues for measurement of oxidant-antioxidant status. The levels of MDA, as an index of lipid peroxidation, increased in blood and tissues. Antioxidant enzyme activities in blood and tissues were modified in chromium groups compared to controls. Simultaneous administration of propolis ameliorated these parameters. The present results suggest that administration of propolis might alleviate chromium-induced oxidative stress. © 2011 Wiley Periodicals, Inc. Environ Toxicol, 2011.","Antioxidant effect of propolis against exposure to chromium in Cyprinus carpio Abs: The aim of the present study was to investigate the ameliorative properties of propolis against the toxic effects of chromium (VI) by examining oxidative damage markers such as lipid peroxidation and the antioxidant defence system components in carp (Cyprinus carpio). The fish were exposed to sublethal concentrations of chromium. Propolis was simultaneously administered to chromium-exposed fish. Treatment was continued for 28 days, and at the end of this period, blood and tissue (liver, kidney, spleen, and gill) samples were collected. Levels of malondialdehyde (MDA) and reduced glutathione (GSH) as well as superoxide dismutase (SOD), catalase (CAT), and glutathione peroxidase (GSH-Px) activities were determined in blood and tissues for measurement of oxidant-antioxidant status. The levels of MDA, as an index of lipid peroxidation, increased in blood and tissues. Antioxidant enzyme activities in blood and tissues were modified in chromium groups compared to controls. Simultaneous administration of propolis ameliorated these parameters. The present results suggest that administration of propolis might alleviate chromium-induced oxidative stress. © 2011 Wiley Periodicals, Inc. Environ Toxicol, 2011."
1509864,da Rocha et al. 2012,Compact and autonomous multiwavelength microanalyzer for in-line and in situ colorimetric determinations,"Nowadays, the attainment of microsystems that integrate most of the stages involved in an analytical process has raised an enormous interest in several research fields. This approach provides experimental set-ups of increased robustness and reliability, which simplify their application to in-line and continuous biomedical and environmental monitoring. In this work, a novel, compact and autonomous microanalyzer aimed at multiwavelength colorimetric determinations is presented. It integrates the microfluidics (a three-dimensional mixer and a 25 mm length &quot;Z-shape&quot; optical flow-cell), a highly versatile multiwavelength optical detection system and the associated electronics for signal processing and drive, all in the same device. The flexibility provided by its design allows the microanalyzer to be operated either in single fixed mode to provide a dedicated photometer or in multiple wavelength mode to obtain discrete pseudospectra. To increase its reliability, automate its operation and allow it to work under unattended conditions, a multicommutation sub-system was developed and integrated with the experimental set-up. The device was initially evaluated in the absence of chemical reactions using four acidochromic dyes and later applied to determine some key environmental parameters such as phenol index, chromium(VI) and nitrite ions. Results were comparable with those obtained with commercial instrumentation and allowed to demonstrate the versatility of the proposed microanalyzer as an autonomous and portable device able to be applied to other analytical methodologies based on colorimetric determinations.","Compact and autonomous multiwavelength microanalyzer for in-line and in situ colorimetric determinations Abs: Nowadays, the attainment of microsystems that integrate most of the stages involved in an analytical process has raised an enormous interest in several research fields. This approach provides experimental set-ups of increased robustness and reliability, which simplify their application to in-line and continuous biomedical and environmental monitoring. In this work, a novel, compact and autonomous microanalyzer aimed at multiwavelength colorimetric determinations is presented. It integrates the microfluidics (a three-dimensional mixer and a 25 mm length &quot;Z-shape&quot; optical flow-cell), a highly versatile multiwavelength optical detection system and the associated electronics for signal processing and drive, all in the same device. The flexibility provided by its design allows the microanalyzer to be operated either in single fixed mode to provide a dedicated photometer or in multiple wavelength mode to obtain discrete pseudospectra. To increase its reliability, automate its operation and allow it to work under unattended conditions, a multicommutation sub-system was developed and integrated with the experimental set-up. The device was initially evaluated in the absence of chemical reactions using four acidochromic dyes and later applied to determine some key environmental parameters such as phenol index, chromium(VI) and nitrite ions. Results were comparable with those obtained with commercial instrumentation and allowed to demonstrate the versatility of the proposed microanalyzer as an autonomous and portable device able to be applied to other analytical methodologies based on colorimetric determinations."
1509863,Zhao et al. 2011,Use of plasma-based spectroscopy and infrared microspectroscopy techniques to determine the uptake and effects of chromium(III) and chromium(VI) on Parkinsonia aculeata,"Chromium uptake and tolerance by Mexican Palo Verde (Parkinsonia aculeata) (MPV) was studied in a six-month experiment with Cr(III) and Cr(VI) at 60 and 10 mg kg(-1), respectively. Chromium and nutrient uptake were determined by ICP-OES and changes in macromolecules were studied by infrared microspectroscopy (IMS). In the Cr(VI)-treated plants, chromium concentration increased in the roots only through the third month, while translocation to stems increased constantly throughout the six months. Cr(III) applications decreased the amount of Zn in leaves and stems (p &lt; or = 0.05). Cr(VI) increased P and S in all plant tissues and increased Ca in roots, but decreased Ca in stems and leaves, and Mg in roots and stems. Cr(III) decreased P in stems and leaves, while both Cr ions decreased K in all MPV tissues. Relative to untreated plant tissue, the IMS revealed significant changes at 1730 cm(-1) and 845 cm(-1). Changes at 1730 cm(-1) indicated that the cortex and xylem of Cr-treated plants were more proteinaceous. Changes at 845 cm(-1) revealed higher lignifications in cortex. However, at the stem level, Cr(VI) decreased lignin deposition in xylem. The data showed that MPV could be useful in the phytoremediation of Cr in moderately impacted soils.","Use of plasma-based spectroscopy and infrared microspectroscopy techniques to determine the uptake and effects of chromium(III) and chromium(VI) on Parkinsonia aculeata Abs: Chromium uptake and tolerance by Mexican Palo Verde (Parkinsonia aculeata) (MPV) was studied in a six-month experiment with Cr(III) and Cr(VI) at 60 and 10 mg kg(-1), respectively. Chromium and nutrient uptake were determined by ICP-OES and changes in macromolecules were studied by infrared microspectroscopy (IMS). In the Cr(VI)-treated plants, chromium concentration increased in the roots only through the third month, while translocation to stems increased constantly throughout the six months. Cr(III) applications decreased the amount of Zn in leaves and stems (p &lt; or = 0.05). Cr(VI) increased P and S in all plant tissues and increased Ca in roots, but decreased Ca in stems and leaves, and Mg in roots and stems. Cr(III) decreased P in stems and leaves, while both Cr ions decreased K in all MPV tissues. Relative to untreated plant tissue, the IMS revealed significant changes at 1730 cm(-1) and 845 cm(-1). Changes at 1730 cm(-1) indicated that the cortex and xylem of Cr-treated plants were more proteinaceous. Changes at 845 cm(-1) revealed higher lignifications in cortex. However, at the stem level, Cr(VI) decreased lignin deposition in xylem. The data showed that MPV could be useful in the phytoremediation of Cr in moderately impacted soils."
1509862,Samuel et al. 2012,Ameliorative effect of vitamin C on hexavalent chromium-induced delay in sexual maturation and oxidative stress in developing Wistar rat ovary and uterus,"Hexavalent chromium (CrVI) is a highly toxic metal and major environmental pollutant and is extensively used in more than 50 industries. The major route of CrVI exposure for the general population is oral intake. Chromium is considered an important nutrient responsible for carbohydrate metabolism. However, excess CrVI exposure is associated with various pathological conditions including reproductive dysfunction. CrVI can traverse the placental barrier and cause wide range of abnormalities in fetal development. Cr is transported to offspring through mother's milk in lactating women exposed to CrVI. Therefore, the present study was carried out to determine the toxic effects of lactational CrVI exposure on ovary and uterus and the beneficial role of vitamin C in preventing/ameliorating the toxic effects of CrVI in developing female Wistar rats. Generation of oxidative stress is considered one of the plausible mechanisms behind Cr-induced cellular deteriorations. The present study evidenced a decrease in the specific activities of antioxidants, serum testosterone and progesterone and an increase in the levels of H?O?, lipid peroxidation (LPO) and follicle stimulating hormone in rats exposed to CrVI when compared to control. CrVI exposure also delayed the sexual maturation and extended the estrous cycle. Simultaneous administration of vitamin C significantly prevented the increase in LPO and enhanced the antioxidant status. These results suggest the protective effect of vitamin C against the CrVI exposure-induced toxicity and attest the significance of antioxidants in diet.","Ameliorative effect of vitamin C on hexavalent chromium-induced delay in sexual maturation and oxidative stress in developing Wistar rat ovary and uterus Abs: Hexavalent chromium (CrVI) is a highly toxic metal and major environmental pollutant and is extensively used in more than 50 industries. The major route of CrVI exposure for the general population is oral intake. Chromium is considered an important nutrient responsible for carbohydrate metabolism. However, excess CrVI exposure is associated with various pathological conditions including reproductive dysfunction. CrVI can traverse the placental barrier and cause wide range of abnormalities in fetal development. Cr is transported to offspring through mother's milk in lactating women exposed to CrVI. Therefore, the present study was carried out to determine the toxic effects of lactational CrVI exposure on ovary and uterus and the beneficial role of vitamin C in preventing/ameliorating the toxic effects of CrVI in developing female Wistar rats. Generation of oxidative stress is considered one of the plausible mechanisms behind Cr-induced cellular deteriorations. The present study evidenced a decrease in the specific activities of antioxidants, serum testosterone and progesterone and an increase in the levels of H?O?, lipid peroxidation (LPO) and follicle stimulating hormone in rats exposed to CrVI when compared to control. CrVI exposure also delayed the sexual maturation and extended the estrous cycle. Simultaneous administration of vitamin C significantly prevented the increase in LPO and enhanced the antioxidant status. These results suggest the protective effect of vitamin C against the CrVI exposure-induced toxicity and attest the significance of antioxidants in diet."
1509861,Kumar et al. 2011,An enhanced adsorption methodology for the detoxification of chromium using n-octylamine impregnated Amberlite XAD-4 polymeric sorbent,"The remediation of heavy metals requires the development of efficient adsorbents. Macroporous polystyrene divinyl benzene based resins are known for their excellent surface characteristics for the effective adsorption of metals. In this paper, we propose an effective adsorption procedure for chromium (VI) using aliphatic primary amine as a guest in Amberlite XAD-4 polymeric sorbent as the host. The adsorption of chromium was quantitative at pH 2.5. The adsorption process was in accordance with pseudo second order kinetics and the maximum adsorption capacity was found to be 75.93 mg g(-1) with good adherence to Langmuir isotherm model. The free energy change ?G(0) increased with temperature and the negative ?H(0) and ?S(0) values indicate the exothermic nature of adsorption and decreased randomness at the adsorbent-solution interface. In aqueous medium, the water molecules surround the hydrophobic host polymeric matrix and this cage effect is responsible for the reduction in entropy of the system. The regeneration of the adsorbent was effective in alkaline medium and the efficacy of the adsorbent was tested for the removal of chromium from tannery waste water.","An enhanced adsorption methodology for the detoxification of chromium using n-octylamine impregnated Amberlite XAD-4 polymeric sorbent Abs: The remediation of heavy metals requires the development of efficient adsorbents. Macroporous polystyrene divinyl benzene based resins are known for their excellent surface characteristics for the effective adsorption of metals. In this paper, we propose an effective adsorption procedure for chromium (VI) using aliphatic primary amine as a guest in Amberlite XAD-4 polymeric sorbent as the host. The adsorption of chromium was quantitative at pH 2.5. The adsorption process was in accordance with pseudo second order kinetics and the maximum adsorption capacity was found to be 75.93 mg g(-1) with good adherence to Langmuir isotherm model. The free energy change ?G(0) increased with temperature and the negative ?H(0) and ?S(0) values indicate the exothermic nature of adsorption and decreased randomness at the adsorbent-solution interface. In aqueous medium, the water molecules surround the hydrophobic host polymeric matrix and this cage effect is responsible for the reduction in entropy of the system. The regeneration of the adsorbent was effective in alkaline medium and the efficacy of the adsorbent was tested for the removal of chromium from tannery waste water."
1509860,Werner and  Burger 2011,Fully computational lead-development of fluoro-olefin polymerization catalysts,"Coordinative polymerization of fluorinated olefins is still a challenging task. We analyzed the catalytic properties of diimido chromium VI compounds computationally by density functional methods. It was found that reactivity predictions depend strongly on the density functional chosen for the computations. Therefore, DFT calculations were calibrated to high level wave function theory calculations. Then geometrical parameters, which can be tuned by a ligand, were scanned to elucidate their influence on the catalytic activity. Having arrived at an optimal parameter set, we randomly assembled chromium complexes from a fragments database and automatically checked for their activities. This led to the proposal of three exemplary catalyst candidates.","Fully computational lead-development of fluoro-olefin polymerization catalysts Abs: Coordinative polymerization of fluorinated olefins is still a challenging task. We analyzed the catalytic properties of diimido chromium VI compounds computationally by density functional methods. It was found that reactivity predictions depend strongly on the density functional chosen for the computations. Therefore, DFT calculations were calibrated to high level wave function theory calculations. Then geometrical parameters, which can be tuned by a ligand, were scanned to elucidate their influence on the catalytic activity. Having arrived at an optimal parameter set, we randomly assembled chromium complexes from a fragments database and automatically checked for their activities. This led to the proposal of three exemplary catalyst candidates."
1509859,Wang et al. 2012,"Individual and joint toxicity effects of Cu, Cr(III), and Cr(VI) on pakchoi: a comparison between solution and soil cultures","The single and joint toxicity effects of Cu, Cr(III), and Cr(VI) on the root elongation of pakchoi in solution and soil were investigated. The median effective concentration (EC(50)) was determined to examine the toxic thresholds of the test elements. The results showed that individual contamination by Cu, Cr(III), or Cr(VI) can inhibit the root elongation of pakchoi. The EC(50) values of the test elements were 2.02 mg/L and 195.8 mg/kg, 62.2 mg/L and 1,773 mg/kg, and 6.88 mg/L and 8.08 mg/kg in solution and soil, respectively. Toxic unit (TU) was introduced to determine the outcome in combined tests, and different behaviors were observed in both solution and soil. The coexistence of Cu and Cr(III) in solution exhibited an antagonistic effect (EC(50mix)?=?1.76 TU(mix)), whereas a synergistic effect was observed in soil (EC(50mix)?=?0.76 TU(mix)). In contrast, combined Cu-Cr(VI) showed a less than additive toxicity both in solution and soil, with EC(50mix) values of 3.31 and 1.24 TU(mix). In conclusion, the coexistence of toxicity in Cu-Cr(III) and Cu-Cr(VI) differs from the toxicity exhibited individually by Cu, Cr(III), and Cr(VI). Heavy metal interaction also changes depending on the medium.","Individual and joint toxicity effects of Cu, Cr(III), and Cr(VI) on pakchoi: a comparison between solution and soil cultures Abs: The single and joint toxicity effects of Cu, Cr(III), and Cr(VI) on the root elongation of pakchoi in solution and soil were investigated. The median effective concentration (EC(50)) was determined to examine the toxic thresholds of the test elements. The results showed that individual contamination by Cu, Cr(III), or Cr(VI) can inhibit the root elongation of pakchoi. The EC(50) values of the test elements were 2.02 mg/L and 195.8 mg/kg, 62.2 mg/L and 1,773 mg/kg, and 6.88 mg/L and 8.08 mg/kg in solution and soil, respectively. Toxic unit (TU) was introduced to determine the outcome in combined tests, and different behaviors were observed in both solution and soil. The coexistence of Cu and Cr(III) in solution exhibited an antagonistic effect (EC(50mix)?=?1.76 TU(mix)), whereas a synergistic effect was observed in soil (EC(50mix)?=?0.76 TU(mix)). In contrast, combined Cu-Cr(VI) showed a less than additive toxicity both in solution and soil, with EC(50mix) values of 3.31 and 1.24 TU(mix). In conclusion, the coexistence of toxicity in Cu-Cr(III) and Cu-Cr(VI) differs from the toxicity exhibited individually by Cu, Cr(III), and Cr(VI). Heavy metal interaction also changes depending on the medium."
1509857,Yu et al. 2011,Wld(S) reduces paraquat-induced cytotoxicity via SIRT1 in non-neuronal cells by attenuating the depletion of NAD,"Wld(S) is a fusion protein with NAD synthesis activity, and has been reported to protect axonal and synaptic compartments of neurons from various mechanical, genetic and chemical insults. However, whether Wld(S) can protect non-neuronal cells against toxic chemicals is largely unknown. Here we found that Wld(S) significantly reduced the cytotoxicity of bipyridylium herbicides paraquat and diquat in mouse embryonic fibroblasts, but had no effect on the cytotoxicity induced by chromium (VI), hydrogen peroxide, etoposide, tunicamycin or brefeldin A. Wld(S) also slowed down the death of mice induced by intraperitoneal injection of paraquat. Further studies demonstrated that Wld(S) markedly attenuated mitochondrial injury including disruption of mitochondrial membrane potential, structural damage and decline of ATP induced by paraquat. Disruption of the NAD synthesis activity of Wld(S) by an H112A or F116S point mutation resulted in loss of its protective function against paraquat-induced cell death. Furthermore, Wld(S) delayed the decrease of intracellular NAD levels induced by paraquat. Similarly, treatment with NAD or its precursor nicotinamide mononucleotide attenuated paraquat-induced cytotoxicity and decline of ATP and NAD levels. In addition, we showed that SIRT1 was required for both exogenous NAD and Wld(S)-mediated cellular protection against paraquat. These findings suggest that NAD and SIRT1 mediate the protective function of Wld(S) against the cytotoxicity induced by paraquat, which provides new clues for the mechanisms underlying the protective function of Wld(S) in both neuronal and non-neuronal cells, and implies that attenuation of NAD depletion may be effective to alleviate paraquat poisoning.","Wld(S) reduces paraquat-induced cytotoxicity via SIRT1 in non-neuronal cells by attenuating the depletion of NAD Abs: Wld(S) is a fusion protein with NAD synthesis activity, and has been reported to protect axonal and synaptic compartments of neurons from various mechanical, genetic and chemical insults. However, whether Wld(S) can protect non-neuronal cells against toxic chemicals is largely unknown. Here we found that Wld(S) significantly reduced the cytotoxicity of bipyridylium herbicides paraquat and diquat in mouse embryonic fibroblasts, but had no effect on the cytotoxicity induced by chromium (VI), hydrogen peroxide, etoposide, tunicamycin or brefeldin A. Wld(S) also slowed down the death of mice induced by intraperitoneal injection of paraquat. Further studies demonstrated that Wld(S) markedly attenuated mitochondrial injury including disruption of mitochondrial membrane potential, structural damage and decline of ATP induced by paraquat. Disruption of the NAD synthesis activity of Wld(S) by an H112A or F116S point mutation resulted in loss of its protective function against paraquat-induced cell death. Furthermore, Wld(S) delayed the decrease of intracellular NAD levels induced by paraquat. Similarly, treatment with NAD or its precursor nicotinamide mononucleotide attenuated paraquat-induced cytotoxicity and decline of ATP and NAD levels. In addition, we showed that SIRT1 was required for both exogenous NAD and Wld(S)-mediated cellular protection against paraquat. These findings suggest that NAD and SIRT1 mediate the protective function of Wld(S) against the cytotoxicity induced by paraquat, which provides new clues for the mechanisms underlying the protective function of Wld(S) in both neuronal and non-neuronal cells, and implies that attenuation of NAD depletion may be effective to alleviate paraquat poisoning."
1509856,Panda et al. 2011,Application of dolochar in the removal of cadmium and hexavalent chromium ions from aqueous solutions,"Dolochar, a waste material generated in sponge iron industry, is processed and put to test as an adsorbent for removal of Cd(II) and Cr(VI) ions from aqueous solutions. The dolochar samples were characterised to determine the different phases and their distribution by reflection microscopy. The analysis indicated that the sample consists of metallic iron, fused carbon, and Ca-Mg bearing phases (Ca-Mg-silicate-oxide) along with lots of voids and pores. The fixed carbon (FC) content of the material is 13.8% with a Langmuir surface area of 81.6m(2)/g and micropore area of 34.1m(2)/g. Batch adsorption experiments have been conducted to study the sorption behaviour of Cd(II) and Cr(VI) ions on dolochar as a function of particle size, contact time, adsorbent dosages, pH and temperature. It is observed that higher pH and temperature enhances sorption of Cd(II) ions. In contrast, the adsorption for Cr(VI) is found to be better in acidic pH in comparison to alkaline media. The equilibrium adsorption isotherm data are tested by applying both Langmuir and Freundlich isotherm models. It is observed that Langmuir isotherm model fitted better compared to the Freundlich model indicating monolayer adsorption. The thermodynamic parameters such as ?G°, ?H° and ?S° indicate the effectiveness of dolochar to remove Cd(II) and Cr(VI) ions from aqueous solution. The kinetics of adsorption is found to better fit to pseudo second order reaction.","Application of dolochar in the removal of cadmium and hexavalent chromium ions from aqueous solutions Abs: Dolochar, a waste material generated in sponge iron industry, is processed and put to test as an adsorbent for removal of Cd(II) and Cr(VI) ions from aqueous solutions. The dolochar samples were characterised to determine the different phases and their distribution by reflection microscopy. The analysis indicated that the sample consists of metallic iron, fused carbon, and Ca-Mg bearing phases (Ca-Mg-silicate-oxide) along with lots of voids and pores. The fixed carbon (FC) content of the material is 13.8% with a Langmuir surface area of 81.6m(2)/g and micropore area of 34.1m(2)/g. Batch adsorption experiments have been conducted to study the sorption behaviour of Cd(II) and Cr(VI) ions on dolochar as a function of particle size, contact time, adsorbent dosages, pH and temperature. It is observed that higher pH and temperature enhances sorption of Cd(II) ions. In contrast, the adsorption for Cr(VI) is found to be better in acidic pH in comparison to alkaline media. The equilibrium adsorption isotherm data are tested by applying both Langmuir and Freundlich isotherm models. It is observed that Langmuir isotherm model fitted better compared to the Freundlich model indicating monolayer adsorption. The thermodynamic parameters such as ?G°, ?H° and ?S° indicate the effectiveness of dolochar to remove Cd(II) and Cr(VI) ions from aqueous solution. The kinetics of adsorption is found to better fit to pseudo second order reaction."
1509855,Vannini et al. 2011,Proteomic changes and molecular effects associated with Cr(III) and Cr(VI) treatments on germinating kiwifruit pollen,"The present study is aimed at identifying molecular changes elicited by Cr(III) and Cr(VI) on germinating kiwifruit pollen. To address this question, comparative proteomic and DNA laddering analyses were performed. While no genotoxic effect was detected, a number of proteins whose accumulation levels were altered by treatments were identified. In particular, the upregulation of some proteins involved in the scavenging response, cell redox homeostasis and lipid synthesis could be interpreted as an oxidative stress response induced by Cr treatment. The strong reduction of two proteins involved in mitochondrial oxidative phosphorylation and a decline in ATP levels were also observed. The decrease of pollen energy availability could be one of the causes of the severe inhibition of the pollen germination observed upon exposure to both Cr(III) and Cr(VI). Finally, proteomic and biochemical data indicate proteasome impairment: the consequential accumulation of misfolded/damaged proteins could be an important molecular mechanism of Cr(III) toxicity in pollen.","Proteomic changes and molecular effects associated with Cr(III) and Cr(VI) treatments on germinating kiwifruit pollen Abs: The present study is aimed at identifying molecular changes elicited by Cr(III) and Cr(VI) on germinating kiwifruit pollen. To address this question, comparative proteomic and DNA laddering analyses were performed. While no genotoxic effect was detected, a number of proteins whose accumulation levels were altered by treatments were identified. In particular, the upregulation of some proteins involved in the scavenging response, cell redox homeostasis and lipid synthesis could be interpreted as an oxidative stress response induced by Cr treatment. The strong reduction of two proteins involved in mitochondrial oxidative phosphorylation and a decline in ATP levels were also observed. The decrease of pollen energy availability could be one of the causes of the severe inhibition of the pollen germination observed upon exposure to both Cr(III) and Cr(VI). Finally, proteomic and biochemical data indicate proteasome impairment: the consequential accumulation of misfolded/damaged proteins could be an important molecular mechanism of Cr(III) toxicity in pollen."
1509854,Kalidhasan et al. 2011,A preliminary spectroscopic investigation on the molecular interaction of metal-diphenylthiocarbazone complex with cellulose biopolymer and its application,"Biopolymer adsorbents are versatile in their application for removal of heavy metals. The present work is focused towards the preliminary study of the interaction of diphenylthiocarbazone (DTZ) complex of chromium(VI) in acidic medium with cellulose biopolymer. Chromium-DTZ complex could be quantitatively adsorbed on a cellulose column in the pH range 1.0-2.5 and the effect of various experimental parameters such as stability of the column and the complex, column breakthrough volume, and interfering ions have been studied in detail. The probable mechanism of adsorption of complex on the cellulose biopolymer was corroborated using Fourier transform infra-red spectroscopy (FT-IR), scanning electron microscopy (SEM), energy dispersive X-ray (EDX) and solid state 13C nuclear magnetic resonance techniques (CP-MAS). The pores formed due to the hydrogen bond between the cellulose layers and then the ensuing occupation of the complex between these layers and on the surface of the biopolymer layer through electrostatic attractive force and ? interaction of aromatic ring with cellulose are expected to play a vital role in the interaction. The cellulose column could be regenerated using environmentally benign polyethylene glycol-400 (PEG-400) in acidic medium. The cellulose biosorbent has been successfully tested to study the removal of chromium as its dithizone complex from synthetic and real waste water samples.","A preliminary spectroscopic investigation on the molecular interaction of metal-diphenylthiocarbazone complex with cellulose biopolymer and its application Abs: Biopolymer adsorbents are versatile in their application for removal of heavy metals. The present work is focused towards the preliminary study of the interaction of diphenylthiocarbazone (DTZ) complex of chromium(VI) in acidic medium with cellulose biopolymer. Chromium-DTZ complex could be quantitatively adsorbed on a cellulose column in the pH range 1.0-2.5 and the effect of various experimental parameters such as stability of the column and the complex, column breakthrough volume, and interfering ions have been studied in detail. The probable mechanism of adsorption of complex on the cellulose biopolymer was corroborated using Fourier transform infra-red spectroscopy (FT-IR), scanning electron microscopy (SEM), energy dispersive X-ray (EDX) and solid state 13C nuclear magnetic resonance techniques (CP-MAS). The pores formed due to the hydrogen bond between the cellulose layers and then the ensuing occupation of the complex between these layers and on the surface of the biopolymer layer through electrostatic attractive force and ? interaction of aromatic ring with cellulose are expected to play a vital role in the interaction. The cellulose column could be regenerated using environmentally benign polyethylene glycol-400 (PEG-400) in acidic medium. The cellulose biosorbent has been successfully tested to study the removal of chromium as its dithizone complex from synthetic and real waste water samples."
1509853,Hedberg et al. 2011,Complexation- and ligand-induced metal release from 316L particles: importance of particle size and crystallographic structure,"Iron, chromium, nickel, and manganese released from gas-atomized AISI 316L stainless steel powders (sized &lt;45 and &lt;4 ?m) were investigated in artificial lysosomal fluid (ALF, pH 4.5) and in solutions of its individual inorganic and organic components to determine its most aggressive component, elucidate synergistic effects, and assess release mechanisms, in dependence of surface changes using atomic absorption spectroscopy, Raman, XPS, and voltammetry. Complexation is the main reason for metal release from 316L particles immersed in ALF. Iron was mainly released, while manganese was preferentially released as a consequence of the reduction of manganese oxide on the surface. These processes resulted in highly complexing media in a partial oxidation of trivalent chromium to hexavalent chromium on the surface. The extent of metal release was partially controlled by surface properties (e.g., availability of elements on the surface and structure of the outermost surface) and partially by the complexation capacity of the different metals with the complexing agents of the different media. In general, compared to the coarse powder (&lt;45 ?m), the fine (&lt;4 ?m) powder displayed significantly higher released amounts of metals per surface area, increased with increased solution complexation capacity, while less amounts of metals were released into non-complexing solutions. Due to the ferritic structure of lower solubility for nickel of the fine powder, more nickel was released into all solutions compared with the coarser powder.","Complexation- and ligand-induced metal release from 316L particles: importance of particle size and crystallographic structure Abs: Iron, chromium, nickel, and manganese released from gas-atomized AISI 316L stainless steel powders (sized &lt;45 and &lt;4 ?m) were investigated in artificial lysosomal fluid (ALF, pH 4.5) and in solutions of its individual inorganic and organic components to determine its most aggressive component, elucidate synergistic effects, and assess release mechanisms, in dependence of surface changes using atomic absorption spectroscopy, Raman, XPS, and voltammetry. Complexation is the main reason for metal release from 316L particles immersed in ALF. Iron was mainly released, while manganese was preferentially released as a consequence of the reduction of manganese oxide on the surface. These processes resulted in highly complexing media in a partial oxidation of trivalent chromium to hexavalent chromium on the surface. The extent of metal release was partially controlled by surface properties (e.g., availability of elements on the surface and structure of the outermost surface) and partially by the complexation capacity of the different metals with the complexing agents of the different media. In general, compared to the coarse powder (&lt;45 ?m), the fine (&lt;4 ?m) powder displayed significantly higher released amounts of metals per surface area, increased with increased solution complexation capacity, while less amounts of metals were released into non-complexing solutions. Due to the ferritic structure of lower solubility for nickel of the fine powder, more nickel was released into all solutions compared with the coarser powder."
1509852,Turyan and  Mandler 1997,Selective Determination of Cr(VI) by a Self-Assembled Monolayer-Based Electrode,"We have developed a selective electrode for chromium(VI), based on a self-assembled monolayer of 4-(mercapto-n-alkyl)pyridinium on gold surfaces, which exhibits unique speciation capabilities. Cr(VI) levels as low as 1 parts per trillion can be detected using a 4-(mercaptoethyl)pyridinium monolayer. The different parameters that govern the analytical performance of these electrodes have been studied in detail and optimized. In addition, the organization of the monolayers has been examined by a variety of surface techniques such as XPS, FT-IR, and electrochemistry. Our results show that structuring and understanding the solid-liquid interface at the molecular level are essential for designing probes with superior analytical characteristics.","Selective Determination of Cr(VI) by a Self-Assembled Monolayer-Based Electrode Abs: We have developed a selective electrode for chromium(VI), based on a self-assembled monolayer of 4-(mercapto-n-alkyl)pyridinium on gold surfaces, which exhibits unique speciation capabilities. Cr(VI) levels as low as 1 parts per trillion can be detected using a 4-(mercaptoethyl)pyridinium monolayer. The different parameters that govern the analytical performance of these electrodes have been studied in detail and optimized. In addition, the organization of the monolayers has been examined by a variety of surface techniques such as XPS, FT-IR, and electrochemistry. Our results show that structuring and understanding the solid-liquid interface at the molecular level are essential for designing probes with superior analytical characteristics."
1509851,Qayyum et al. 2012,Effect of nickel and chromium exposure on buccal cells of electroplaters,"The electroplating industry commonly involves the use of nickel and chromium. An assessment of the genotoxic effects of these metals can be carried out by micronucleus (MN) test in buccal cells. Other nuclear anomalies (NA) observed in buccal cells viz., karyorrhexis, pyknosis and karyolysis are also the indicators of genotoxicity. The current study aims at determining the extent of genotoxic damage in relation to the duration of exposure to nickel and hexavalent chromium via micronuclei induction and other nuclear anomalies. The present investigation included 150 subjects of which 50 individuals with no history of nickel/chromium exposure (Group I) were taken as control, 50 electroplaters exposed to nickel and hexavalent chromium for duration of less than 10 years (Group II) and 50 electroplaters exposed for ?10 years (Group III) were included. Slides of buccal cells were prepared and the frequency of MN (‰) and NA (‰) were calculated. ANOVA was applied to test significance. Results were considered significant at p &lt; 0.05 and p &lt; 0.001. Group III showed the highest MN frequency (1.08 ± 0.54‰, p &lt; 0.05), karyorrhexis (20.75 ± 6.29, p &lt; 0.05), karyolysis (3.50 ± 1.91, p &lt; 0.001), binucleate (4.75 ± 2.75, p &lt; 0.05) and enucleated cells (5.75 ± 1.70, p &lt; 0.05). Significant increase in frequencies between Group II and III was found as duration of exposure increased. Plasma nickel and chromium levels were also determined which showed a positive correlation with frequency MN and other nuclear abnormalities (p &lt; 0.01).","Effect of nickel and chromium exposure on buccal cells of electroplaters Abs: The electroplating industry commonly involves the use of nickel and chromium. An assessment of the genotoxic effects of these metals can be carried out by micronucleus (MN) test in buccal cells. Other nuclear anomalies (NA) observed in buccal cells viz., karyorrhexis, pyknosis and karyolysis are also the indicators of genotoxicity. The current study aims at determining the extent of genotoxic damage in relation to the duration of exposure to nickel and hexavalent chromium via micronuclei induction and other nuclear anomalies. The present investigation included 150 subjects of which 50 individuals with no history of nickel/chromium exposure (Group I) were taken as control, 50 electroplaters exposed to nickel and hexavalent chromium for duration of less than 10 years (Group II) and 50 electroplaters exposed for ?10 years (Group III) were included. Slides of buccal cells were prepared and the frequency of MN (‰) and NA (‰) were calculated. ANOVA was applied to test significance. Results were considered significant at p &lt; 0.05 and p &lt; 0.001. Group III showed the highest MN frequency (1.08 ± 0.54‰, p &lt; 0.05), karyorrhexis (20.75 ± 6.29, p &lt; 0.05), karyolysis (3.50 ± 1.91, p &lt; 0.001), binucleate (4.75 ± 2.75, p &lt; 0.05) and enucleated cells (5.75 ± 1.70, p &lt; 0.05). Significant increase in frequencies between Group II and III was found as duration of exposure increased. Plasma nickel and chromium levels were also determined which showed a positive correlation with frequency MN and other nuclear abnormalities (p &lt; 0.01)."
1509850,Chakraborty et al. 2011,Use of immunomagnetic separation for the detection of Desulfovibrio vulgaris from environmental samples,"Immunomagnetic separation (IMS) has proved highly efficient for recovering microorganisms from heterogeneous samples. Current investigation targeted the separation of viable cells of the sulfate-reducing bacterium, Desulfovibrio vulgaris. Streptavidin-coupled paramagnetic beads and biotin labeled antibodies raised against surface antigens of this microorganism were used to capture D. vulgaris cells in both bioreactor grown laboratory samples and from extremely low-biomass environmental soil and subsurface drilling samples. Initial studies on detection, recovery efficiency and viability for IMS were performed with laboratory grown D. vulgaris cells using various cell densities. Efficiency of cell isolation and recovery (i.e., release of the microbial cells from the beads following separation) was followed by microscopic imaging and acridine orange direct counts (AODC). Excellent recovery efficiency encouraged the use of IMS to capture Desulfovibrio spp. cells from low-biomass environmental samples. The environmental samples were obtained from a radionuclide-contaminated site in Germany and the chromium (VI)-contaminated Hanford site, an ongoing bioremediation project of the U.S. Department of Energy. Field deployable IMS technology may greatly facilitate environmental sampling and bioremediation process monitoring and enable transcriptomics and proteomics/metabolomics-based studies directly on cells collected from the field.","Use of immunomagnetic separation for the detection of Desulfovibrio vulgaris from environmental samples Abs: Immunomagnetic separation (IMS) has proved highly efficient for recovering microorganisms from heterogeneous samples. Current investigation targeted the separation of viable cells of the sulfate-reducing bacterium, Desulfovibrio vulgaris. Streptavidin-coupled paramagnetic beads and biotin labeled antibodies raised against surface antigens of this microorganism were used to capture D. vulgaris cells in both bioreactor grown laboratory samples and from extremely low-biomass environmental soil and subsurface drilling samples. Initial studies on detection, recovery efficiency and viability for IMS were performed with laboratory grown D. vulgaris cells using various cell densities. Efficiency of cell isolation and recovery (i.e., release of the microbial cells from the beads following separation) was followed by microscopic imaging and acridine orange direct counts (AODC). Excellent recovery efficiency encouraged the use of IMS to capture Desulfovibrio spp. cells from low-biomass environmental samples. The environmental samples were obtained from a radionuclide-contaminated site in Germany and the chromium (VI)-contaminated Hanford site, an ongoing bioremediation project of the U.S. Department of Energy. Field deployable IMS technology may greatly facilitate environmental sampling and bioremediation process monitoring and enable transcriptomics and proteomics/metabolomics-based studies directly on cells collected from the field."
1509849,Sun et al. 2011,Degradation of pyridine by one Rhodococcus strain in the presence of chromium (VI) or phenol,"A Rhodococcus strain, Chr-9, which has the ability to degrade pyridine and phenol and reduce chromium (VI) (Cr (VI)) was isolated. The strain could grow with pyridine as the sole carbon and nitrogen source, and its pyridine-degradation capability was enhanced by 100 mg l(-1) phenol; however, the degradation of pyridine was inhibited when the phenol concentration was greater than 400 mg l(-1). The hydroxylation of pyridine suggested that the stimulation and inhibition of phenol to the pyridine degradation may be attributed to competition of phenol and pyridine for the hydroxylase gene. Strain Chr-9 was also able to reduce Cr (VI) when glucose and LB was used as the carbon source; however, the Cr (VI) reduction did not occur when pyridine was the sole carbon and energy source. In addition, strain Chr-9 could reduce Cr (VI) and simultaneously degrade pyridine in the presence of glucose. To the best of our knowledge, strain Chr-9 is the first Rhodococcus strain reported to degrade pyridine in the presence of Cr (VI), and the first strain with the pyridine degradation being stimulated by low concentrations of phenol.","Degradation of pyridine by one Rhodococcus strain in the presence of chromium (VI) or phenol Abs: A Rhodococcus strain, Chr-9, which has the ability to degrade pyridine and phenol and reduce chromium (VI) (Cr (VI)) was isolated. The strain could grow with pyridine as the sole carbon and nitrogen source, and its pyridine-degradation capability was enhanced by 100 mg l(-1) phenol; however, the degradation of pyridine was inhibited when the phenol concentration was greater than 400 mg l(-1). The hydroxylation of pyridine suggested that the stimulation and inhibition of phenol to the pyridine degradation may be attributed to competition of phenol and pyridine for the hydroxylase gene. Strain Chr-9 was also able to reduce Cr (VI) when glucose and LB was used as the carbon source; however, the Cr (VI) reduction did not occur when pyridine was the sole carbon and energy source. In addition, strain Chr-9 could reduce Cr (VI) and simultaneously degrade pyridine in the presence of glucose. To the best of our knowledge, strain Chr-9 is the first Rhodococcus strain reported to degrade pyridine in the presence of Cr (VI), and the first strain with the pyridine degradation being stimulated by low concentrations of phenol."
1509848,Lai and  Tseng 2011,Role of 5-thio-(2-nitrobenzoic acid)-capped gold nanoparticles in the sensing of chromium(vi): remover and sensor,"This study describes a simple, rapid method for sensing Cr(vi) using 5-thio-(2-nitrobenzoic acid) modified gold nanoparticles (TNBA-AuNPs) as a remover for Cr(iii) and as a sensor for Cr(vi). We discovered that TNBA-AuNPs were dispersed in the presence of Cr(vi), whereas Cr(iii) induced the aggregation of TNBA-AuNPs. Due to this phenomenon, TNBA-AuNPs can be used as a sorbent material for the removal of &gt;90% Cr(iii), without removing Cr(vi). After centrifuging a solution containing Cr(iii), Cr(vi), and TNBA-AuNPs, Cr(iii) and Cr(vi) were separately present in the precipitate and supernatant. In other words, TNBA-AuNPs are capable of separating a mixture of Cr(iii) and Cr(vi). The addition of ascorbic acid to the supernatant resulted in a reduction of Cr(vi) to Cr(iii), driving the aggregation of TNBA-AuNPs. The selectivity of this approach is more than 1000-fold for Cr(vi) over other metal ions. The minimum detectable concentration of Cr(vi) was 1 ?M using this approach. Inductively coupled plasma mass spectrometry provided an alternative for the quantification of Cr(iii) and Cr(vi) after a mixture of Cr(iii) and Cr(vi) had been separated by TNBA-AuNPs. The applicability of this approach was validated through the analysis of Cr(vi) in environmental water samples.","Role of 5-thio-(2-nitrobenzoic acid)-capped gold nanoparticles in the sensing of chromium(vi): remover and sensor Abs: This study describes a simple, rapid method for sensing Cr(vi) using 5-thio-(2-nitrobenzoic acid) modified gold nanoparticles (TNBA-AuNPs) as a remover for Cr(iii) and as a sensor for Cr(vi). We discovered that TNBA-AuNPs were dispersed in the presence of Cr(vi), whereas Cr(iii) induced the aggregation of TNBA-AuNPs. Due to this phenomenon, TNBA-AuNPs can be used as a sorbent material for the removal of &gt;90% Cr(iii), without removing Cr(vi). After centrifuging a solution containing Cr(iii), Cr(vi), and TNBA-AuNPs, Cr(iii) and Cr(vi) were separately present in the precipitate and supernatant. In other words, TNBA-AuNPs are capable of separating a mixture of Cr(iii) and Cr(vi). The addition of ascorbic acid to the supernatant resulted in a reduction of Cr(vi) to Cr(iii), driving the aggregation of TNBA-AuNPs. The selectivity of this approach is more than 1000-fold for Cr(vi) over other metal ions. The minimum detectable concentration of Cr(vi) was 1 ?M using this approach. Inductively coupled plasma mass spectrometry provided an alternative for the quantification of Cr(iii) and Cr(vi) after a mixture of Cr(iii) and Cr(vi) had been separated by TNBA-AuNPs. The applicability of this approach was validated through the analysis of Cr(vi) in environmental water samples."
1509847,Duran et al. 2011,Speciation of Cr(III) and Cr(VI) in geological and water samples by ytterbium(III) hydroxide coprecipitation system and atomic absorption spectrometry,"A novel coprecipitation method with ytterbium(III) hydroxide has been established for speciation of Cr(III) and Cr(VI) in geological and water samples. At pH 10, while Cr(III) was quantitatively recovered, Cr(VI) was recovered under 10% levels. Total chromium was determined reducing of Cr(VI) to Cr(III) in acidic media with KI reagent. The concentration of Cr(VI) was calculated by the concentration difference between the total chromium and Cr(III). For the quantitative recovery of Cr(III), parameters such as pH, amount of ytterbium, centrifugation time and speed, matrix effect, KI amount, and sample volume were investigated. The preconcentration factor was 30. The limit of detection was obtained as 1.1 ?g/L for Cr(III). The accuracy was checked by analyte addition and analyses of standard reference materials (TMDA-54.4 Certified Reference Water, NIST 2710 Montana Soil). Method has been successfully applied to the chromium speciation for industrial waste water of leather factories located in Bor-Nigde, and also for mine and soil samples.","Speciation of Cr(III) and Cr(VI) in geological and water samples by ytterbium(III) hydroxide coprecipitation system and atomic absorption spectrometry Abs: A novel coprecipitation method with ytterbium(III) hydroxide has been established for speciation of Cr(III) and Cr(VI) in geological and water samples. At pH 10, while Cr(III) was quantitatively recovered, Cr(VI) was recovered under 10% levels. Total chromium was determined reducing of Cr(VI) to Cr(III) in acidic media with KI reagent. The concentration of Cr(VI) was calculated by the concentration difference between the total chromium and Cr(III). For the quantitative recovery of Cr(III), parameters such as pH, amount of ytterbium, centrifugation time and speed, matrix effect, KI amount, and sample volume were investigated. The preconcentration factor was 30. The limit of detection was obtained as 1.1 ?g/L for Cr(III). The accuracy was checked by analyte addition and analyses of standard reference materials (TMDA-54.4 Certified Reference Water, NIST 2710 Montana Soil). Method has been successfully applied to the chromium speciation for industrial waste water of leather factories located in Bor-Nigde, and also for mine and soil samples."
1509846,Okello et al. 2011,Environmental applications of poly(amic acid)-based nanomaterials,"Nanoscale materials offer new possibilities for the development of novel remediation and environmental monitoring technologies. Different nanoscale materials have been exploited for preventing environmental degradation and pollutant transformation. However, the rapid self-aggregation of nanoparticles or their association with suspended solids or sediments where they could bioaccumulate supports the need for polymeric coatings to improve mobility, allows faster site cleanups and reduces remediation cost. The ideal material must be able to coordinate different nanomaterials functionalities and exhibit the potential for reusability. We hereby describe two novel environmental applications of nanostructured poly (amic acid)-based (nPAA) materials. In the first application, nPAA was used as both reductant and stabilizer during the in situ chemical reduction of chromium(vi) to chromium(iii). Results showed that Cr(vi) species were rapidly reduced within the concentration range of 10(-1) to 10(2) mM with efficiency of 99.9% at 40 °C in water samples and 90% at 40 °C in soil samples respectively. Furthermore, the presence of PdNPs on the PAA-Au electrode was found to significantly enhance the rate of reduction. In the second application, nPAA membranes were tested as filters to capture, isolate and detect nanosilver. Preliminary results demonstrate the capability of the nPAA membranes to quantitatively capture nanoparticles from suspension and quantify their abundance on the membranes. Silver nanoparticles detection at concentrations near the toxic threshold of silver was also demonstrated.","Environmental applications of poly(amic acid)-based nanomaterials Abs: Nanoscale materials offer new possibilities for the development of novel remediation and environmental monitoring technologies. Different nanoscale materials have been exploited for preventing environmental degradation and pollutant transformation. However, the rapid self-aggregation of nanoparticles or their association with suspended solids or sediments where they could bioaccumulate supports the need for polymeric coatings to improve mobility, allows faster site cleanups and reduces remediation cost. The ideal material must be able to coordinate different nanomaterials functionalities and exhibit the potential for reusability. We hereby describe two novel environmental applications of nanostructured poly (amic acid)-based (nPAA) materials. In the first application, nPAA was used as both reductant and stabilizer during the in situ chemical reduction of chromium(vi) to chromium(iii). Results showed that Cr(vi) species were rapidly reduced within the concentration range of 10(-1) to 10(2) mM with efficiency of 99.9% at 40 °C in water samples and 90% at 40 °C in soil samples respectively. Furthermore, the presence of PdNPs on the PAA-Au electrode was found to significantly enhance the rate of reduction. In the second application, nPAA membranes were tested as filters to capture, isolate and detect nanosilver. Preliminary results demonstrate the capability of the nPAA membranes to quantitatively capture nanoparticles from suspension and quantify their abundance on the membranes. Silver nanoparticles detection at concentrations near the toxic threshold of silver was also demonstrated."
1509845,Pakzadeh and  Batista 2011,Chromium removal from ion-exchange waste brines with calcium polysulfide,"Chromium removal from ion-exchange (IX) brines presents a serious challenge to the water industry. Although chromium removal with calcium polysulfide (CaS(5)) from drinking waters has been investigated somewhat, its removal from ion-exchange brines has not been evaluated to date. In this study, a Central Composite Design as well as experimental coagulation tests were performed to investigate the influence of pH, CaS(5)/Cr(VI) molar ratio, alkalinity, and ionic strength in the removal of chromium from IX brines. The optimal pH range for the process was found to be pH 8-10.3 and brine alkalinity did not affect coagulation. The efficiency of chromium removal improved only slightly when the ionic strength increased from 0.1 M to 1.5 M; no significant difference was observed for an ionic strength change from 1.5 to 2.1 M. For chromium (VI) concentrations typically found in ion-exchange brines, a CaS(5)/Cr(VI) molar ratio varying from 0.6 to 1.4 was needed to obtain a final chromium concentration &lt;5 mg/L. Maximum efficiency for total chromium removal was obtained when oxidation reduction potentials were between -0.1 and 0 (V). Solids concentrations (0.2-1.5 g/L) were found to increase proportionally with CaS(5) dosage. The results of this research are directly applicable to the treatment of residual waste brines containing chromium.","Chromium removal from ion-exchange waste brines with calcium polysulfide Abs: Chromium removal from ion-exchange (IX) brines presents a serious challenge to the water industry. Although chromium removal with calcium polysulfide (CaS(5)) from drinking waters has been investigated somewhat, its removal from ion-exchange brines has not been evaluated to date. In this study, a Central Composite Design as well as experimental coagulation tests were performed to investigate the influence of pH, CaS(5)/Cr(VI) molar ratio, alkalinity, and ionic strength in the removal of chromium from IX brines. The optimal pH range for the process was found to be pH 8-10.3 and brine alkalinity did not affect coagulation. The efficiency of chromium removal improved only slightly when the ionic strength increased from 0.1 M to 1.5 M; no significant difference was observed for an ionic strength change from 1.5 to 2.1 M. For chromium (VI) concentrations typically found in ion-exchange brines, a CaS(5)/Cr(VI) molar ratio varying from 0.6 to 1.4 was needed to obtain a final chromium concentration &lt;5 mg/L. Maximum efficiency for total chromium removal was obtained when oxidation reduction potentials were between -0.1 and 0 (V). Solids concentrations (0.2-1.5 g/L) were found to increase proportionally with CaS(5) dosage. The results of this research are directly applicable to the treatment of residual waste brines containing chromium."
1509844,Li et al. 2010,Reduction and immobilization of chromium(VI) by nano-scale Fe0 particles supported on reproducible PAA/PVDF membrane,"A new class of nano-scale Fe0 particles (NZVI) supported on a PAA/PVDF membrane (NZVI-PAA/PVDF) were synthesized and the feasibility of using NZVI-PAA/PVDF for reductive immobilization of Cr(VI) in water was investigated through laboratory batch tests. The results showed that the Cr(VI) removal capacity of NZVI-PAA/PVDF was 181 mg Cr/g Fe at an initial Cr(VI) concentration of 20 mg L(-1) under pH 6.5 +/- 0.1. XPS results showed that Cr(VI) was converted to nontoxic Cr(III). Interfering ions exerted various degrees of impact on NZVI-PAA/PVDF's Cr(VI) removal capacity. Specifically, Ca2+ alone showed the mildest impact while the presence of ions (Mg2+ and HCO3-) exerted the greatest impact. An advantage of NZVI-PAA/PVDF is that the nano-scale Fe0 and resultant particles were combined within a PAA/PVDF membrane, which prevents secondary pollution. Moreover, a piece of PAA/PVDF membrane (4.7 cm diameter) can still support 6.51 mg of nano-scale Fe0 particles after being renewed.","Reduction and immobilization of chromium(VI) by nano-scale Fe0 particles supported on reproducible PAA/PVDF membrane Abs: A new class of nano-scale Fe0 particles (NZVI) supported on a PAA/PVDF membrane (NZVI-PAA/PVDF) were synthesized and the feasibility of using NZVI-PAA/PVDF for reductive immobilization of Cr(VI) in water was investigated through laboratory batch tests. The results showed that the Cr(VI) removal capacity of NZVI-PAA/PVDF was 181 mg Cr/g Fe at an initial Cr(VI) concentration of 20 mg L(-1) under pH 6.5 +/- 0.1. XPS results showed that Cr(VI) was converted to nontoxic Cr(III). Interfering ions exerted various degrees of impact on NZVI-PAA/PVDF's Cr(VI) removal capacity. Specifically, Ca2+ alone showed the mildest impact while the presence of ions (Mg2+ and HCO3-) exerted the greatest impact. An advantage of NZVI-PAA/PVDF is that the nano-scale Fe0 and resultant particles were combined within a PAA/PVDF membrane, which prevents secondary pollution. Moreover, a piece of PAA/PVDF membrane (4.7 cm diameter) can still support 6.51 mg of nano-scale Fe0 particles after being renewed."
1509843,Mohanty et al. 2012,"Bio-concentration of chromium--an in situ phytoremediation study at South Kaliapani chromite mining area of Orissa, India","Mine waste water at South Kaliapani usually contains toxic levels of hexavalent Cr(VI). The present in situ study was conducted at South Kaliapani chromite mine area in Orissa state, India, to assess the phytoremediation ability of three plants, namely, rice (Oryza sativa L.), paragrass (Brachiaria mutica), and an aquatic weed (Eichhornia crassipes), in attenuating Cr(VI) from mine waste water and to correlate the bio-concentration factors (BCF) of Cr. Water hyacinth (E. crassipes) showed 24% to 54% reduction whereas paragrass (B. mutica) was able to reduce 18% to 33% of Cr(VI) from mine water. This reduction was studied over a period of 100 days of plant growth. The reduction was observed through a passage of a sum total of 2,000 sq. ft. cultivated plots and ponds separately. Reduction in Cr(VI) content in mine water varies with plant age as well as with the distance of passage. Cr accumulation and BCF values increased with high soil Cr levels as well as the age of plants. High BCF and transportation index (Ti) values, i.e., 10,924 and 32.09, respectively, were noted for water hyacinth. The Ti values indicated that the root-to-shoot translocation of Cr was very high after 100 days of growth. The total accumulation rate was maximum (8.29 mg Cr kg dry biomass(-1) day (-1)) in paragrass. The BCF values for roots were noted to be higher than those of leaves, stems, and grains of the 125-day-old plants. Hence, paragrass and water hyacinth may be used as tools of phytoremediation to combat the problem of in situ Cr contamination.","Bio-concentration of chromium--an in situ phytoremediation study at South Kaliapani chromite mining area of Orissa, India Abs: Mine waste water at South Kaliapani usually contains toxic levels of hexavalent Cr(VI). The present in situ study was conducted at South Kaliapani chromite mine area in Orissa state, India, to assess the phytoremediation ability of three plants, namely, rice (Oryza sativa L.), paragrass (Brachiaria mutica), and an aquatic weed (Eichhornia crassipes), in attenuating Cr(VI) from mine waste water and to correlate the bio-concentration factors (BCF) of Cr. Water hyacinth (E. crassipes) showed 24% to 54% reduction whereas paragrass (B. mutica) was able to reduce 18% to 33% of Cr(VI) from mine water. This reduction was studied over a period of 100 days of plant growth. The reduction was observed through a passage of a sum total of 2,000 sq. ft. cultivated plots and ponds separately. Reduction in Cr(VI) content in mine water varies with plant age as well as with the distance of passage. Cr accumulation and BCF values increased with high soil Cr levels as well as the age of plants. High BCF and transportation index (Ti) values, i.e., 10,924 and 32.09, respectively, were noted for water hyacinth. The Ti values indicated that the root-to-shoot translocation of Cr was very high after 100 days of growth. The total accumulation rate was maximum (8.29 mg Cr kg dry biomass(-1) day (-1)) in paragrass. The BCF values for roots were noted to be higher than those of leaves, stems, and grains of the 125-day-old plants. Hence, paragrass and water hyacinth may be used as tools of phytoremediation to combat the problem of in situ Cr contamination."
1509842,Sharma et al. 2011,Effect of 28-homobrassinolide on antioxidant defence system in Raphanus sativus L. under chromium toxicity,"Heavy metals have emerged as major environmental contaminants due to rapid industrialization and urbanization. The genotoxic, mutagenic and carcinogenic effects of heavy metal like chromium (Cr) on man, animals and plants have been documented. In plants, accumulation of heavy metals beyond critical levels generates oxidative stress. This stress is generally overcome by antioxidant defence system and stress shielding phytohormones. Thus, the present study has been focused to analyze the effect of one of imperative group of plant hormones, i.e., brassinosteroids (BRs) which have been reported for its protective properties for wide array of environmental stresses. Raphanus sativus L. (Pusa Chetaki) seeds pre-treated with different concentrations of 28-homobrassinolide (28-HBL) were raised under various concentrations of Cr(VI). It was observed that 28-HBL treatment considerably reduced the impact of Cr-stress on seedlings which was evinced upon analysis of morphological and biochemical parameters of 7-days old radish seedlings. The toxic effects of Cr in terms of reduced growth, lowered contents of chlorophyll (Chl), protein, proline; increased malondialdehyde (MDA) content and elevated metal uptake were ameliorated by applications of 28-HBL. Also, the activities of all the antioxidant enzymes except guaiacol peroxidase (POD), increased significantly when subjected to Cr stress in combination with 28-HBL. Overall, seed pre-soaking treatment of 28-HBL at 10(-7) M was most effective in ameliorating Cr stress. The present work emphasizes the protective role of 28-HBL on regulation of antioxidant enzymes and its possible link in amelioration of stress in plants.","Effect of 28-homobrassinolide on antioxidant defence system in Raphanus sativus L. under chromium toxicity Abs: Heavy metals have emerged as major environmental contaminants due to rapid industrialization and urbanization. The genotoxic, mutagenic and carcinogenic effects of heavy metal like chromium (Cr) on man, animals and plants have been documented. In plants, accumulation of heavy metals beyond critical levels generates oxidative stress. This stress is generally overcome by antioxidant defence system and stress shielding phytohormones. Thus, the present study has been focused to analyze the effect of one of imperative group of plant hormones, i.e., brassinosteroids (BRs) which have been reported for its protective properties for wide array of environmental stresses. Raphanus sativus L. (Pusa Chetaki) seeds pre-treated with different concentrations of 28-homobrassinolide (28-HBL) were raised under various concentrations of Cr(VI). It was observed that 28-HBL treatment considerably reduced the impact of Cr-stress on seedlings which was evinced upon analysis of morphological and biochemical parameters of 7-days old radish seedlings. The toxic effects of Cr in terms of reduced growth, lowered contents of chlorophyll (Chl), protein, proline; increased malondialdehyde (MDA) content and elevated metal uptake were ameliorated by applications of 28-HBL. Also, the activities of all the antioxidant enzymes except guaiacol peroxidase (POD), increased significantly when subjected to Cr stress in combination with 28-HBL. Overall, seed pre-soaking treatment of 28-HBL at 10(-7) M was most effective in ameliorating Cr stress. The present work emphasizes the protective role of 28-HBL on regulation of antioxidant enzymes and its possible link in amelioration of stress in plants."
1509841,Kim et al. 2011,Determination of hexavalent chromium (Cr(VI)) in plastics using organic-assisted alkaline extraction,"An organic-assisted alkaline extraction method was developed for the determination of hexavalent chromium (Cr(VI)) in plastics. The solubilization of polymer as a pre-step of the alkaline extraction provided good extraction efficiency of Cr(VI) from the sample. The optimization of the experimental conditions affecting the extraction and UV-vis spectrophotometric analysis was accomplished by evaluating the recovery rate of Cr(VI) through the analysis of Cr(VI) in in-house polymer reference materials (RMs). With the proposed method, most of the Cr(VI) in polymers was released within a short extraction time of 30 min and the Cr(III)-DPCO complex can be kept stable for 24 h. The heating for the extraction of the Cr(VI) was not necessary. The optimal pH of the final solution was fixed at 2.0. The proposed extraction method was applied successfully for the determination of Cr(III) and Cr(VI) in spiked samples. The practical applicability of this new method was evaluated through the analysis of Cr(VI) in in-house polymer RMs. The good linearity was demonstrated at desired concentrations of the range 0-3.3 mg L(-1). The detection limits were quite low, varying from 0.0061 to 0.0285 mg L(-1). The recovery of Cr(VI) was between 97 and 106%, and the relative standard deviation (R.S.D.) was below 6%.","Determination of hexavalent chromium (Cr(VI)) in plastics using organic-assisted alkaline extraction Abs: An organic-assisted alkaline extraction method was developed for the determination of hexavalent chromium (Cr(VI)) in plastics. The solubilization of polymer as a pre-step of the alkaline extraction provided good extraction efficiency of Cr(VI) from the sample. The optimization of the experimental conditions affecting the extraction and UV-vis spectrophotometric analysis was accomplished by evaluating the recovery rate of Cr(VI) through the analysis of Cr(VI) in in-house polymer reference materials (RMs). With the proposed method, most of the Cr(VI) in polymers was released within a short extraction time of 30 min and the Cr(III)-DPCO complex can be kept stable for 24 h. The heating for the extraction of the Cr(VI) was not necessary. The optimal pH of the final solution was fixed at 2.0. The proposed extraction method was applied successfully for the determination of Cr(III) and Cr(VI) in spiked samples. The practical applicability of this new method was evaluated through the analysis of Cr(VI) in in-house polymer RMs. The good linearity was demonstrated at desired concentrations of the range 0-3.3 mg L(-1). The detection limits were quite low, varying from 0.0061 to 0.0285 mg L(-1). The recovery of Cr(VI) was between 97 and 106%, and the relative standard deviation (R.S.D.) was below 6%."
1509840,Chhikara et al. 2010,Chromium (VI) biosorption by immobilized Aspergillus niger in continuous flow system with special reference to FTIR analysis,"Aspergillus niger was treated with acid and immobilized in calcium alginate matrix. The dynamic removal of Cr (VI) ion was studied using continuously fed column packed with immobilized biosorbent beads. Column experiments were carried out to study the effect of various bed heights (20, 30, 40 cm) under different flow rates (5, 7.5, 10 ml min(-1)) on efficiency of biosorption. The maximum time (1020 minutes; 17 hr) before breakthrough point was observed in case of 40 cm bed height with flow rate of 5ml min(-1). FTIR analysis of acid treated immobilized A. niger was used fora qualitative and preliminary analysis of chemical functional groups present on its cell wall which provided the information on nature of cell wall and Cr (VI) interaction during the process of biosorption. The IR spectra of biosorbent recorded before and after chromium biosorption had shown some changes in the band patterns, which were finally analyzed and was found that chemical interaction such as ion-exchange between carboxyl (-COOH), hydroxyl (-OH) and amine (-NH2) group of biosorbent and Chromium ion were mainlyinvolved in biosorption of Cr (VI) onto A. niger cell wall surface. The biosorbed metal was eluted from biosorbent by using 0.1 M H2SO4 as eluant. Immobilized biosorbent could be reused for five consecutive biosorption and desorption cycles without apparent loss of efficiency after its reconditioning. Considering all above factors together this paper discusses the efficient chromium biosorption process carried out by immobilized A. niger biosorbent.","Chromium (VI) biosorption by immobilized Aspergillus niger in continuous flow system with special reference to FTIR analysis Abs: Aspergillus niger was treated with acid and immobilized in calcium alginate matrix. The dynamic removal of Cr (VI) ion was studied using continuously fed column packed with immobilized biosorbent beads. Column experiments were carried out to study the effect of various bed heights (20, 30, 40 cm) under different flow rates (5, 7.5, 10 ml min(-1)) on efficiency of biosorption. The maximum time (1020 minutes; 17 hr) before breakthrough point was observed in case of 40 cm bed height with flow rate of 5ml min(-1). FTIR analysis of acid treated immobilized A. niger was used fora qualitative and preliminary analysis of chemical functional groups present on its cell wall which provided the information on nature of cell wall and Cr (VI) interaction during the process of biosorption. The IR spectra of biosorbent recorded before and after chromium biosorption had shown some changes in the band patterns, which were finally analyzed and was found that chemical interaction such as ion-exchange between carboxyl (-COOH), hydroxyl (-OH) and amine (-NH2) group of biosorbent and Chromium ion were mainlyinvolved in biosorption of Cr (VI) onto A. niger cell wall surface. The biosorbed metal was eluted from biosorbent by using 0.1 M H2SO4 as eluant. Immobilized biosorbent could be reused for five consecutive biosorption and desorption cycles without apparent loss of efficiency after its reconditioning. Considering all above factors together this paper discusses the efficient chromium biosorption process carried out by immobilized A. niger biosorbent."
1509839,Horie et al. 2013,Chromium(III) oxide nanoparticles induced remarkable oxidative stress and apoptosis on culture cells,"Chromium(III) oxide (Cr(2)O(3)) is used for industrial applications such as catalysts and pigments. In the classical form, namely the fine particle, Cr(2)O(3) is insoluble and chemically stable. It is classified as a low-toxicity chromium compound. Recently, industrial application of nanoparticles (a new form composed of small particles with a diameter of ?100 nm, in at least one dimension) has been increasing. Cellular effects induced by Cr(2)O(3) nanoparticles are not known. To shed light upon this, the release of soluble chromium from Cr(2)O(3) nano- and fine-particles in culture medium was compared. Fine Cr(2)O(3) particles were insoluble in the culture medium; on the contrary, Cr(2)O(3) nanoparticles released soluble hexavalent chromium into the culture medium. Cr(2)O(3) nanoparticles showed severe cytotoxicity. The effect of Cr(2)O(3) nanoparticles on cell viability was higher than that of fine particles. Cr(2)O(3) nanoparticles showed cytotoxicity equal to that of hexavalent chromium (K(2)Cr(2)O(7)). Human lung carcinoma A549 cells and human keratinocyte HaCaT cells showed an increase in intracellular reactive oxygen species (ROS) level and activation of antioxidant defense systems on exposure to Cr(2)O(3) nanoparticles. Exposure of Cr(2)O(3) nanoparticles led to caspase-3 activation, showing that the decrease in cell viability by exposure to Cr(2)O(3) nanoparticles was caused by apoptosis. Cellular responses were stronger in the Cr(2)O(3) nanoparticles-exposed cells than in fine Cr(2)O(3) - and CrCl(3) -exposed cells. Cellular uptake of Cr(2)O(3) particles were observed in nano- and fine-particles. The cellular influence of the extracellular soluble trivalent chromium was lower than that of Cr(2)O(3) nanoparticles. Cr(2)O(3) nanoparticles showed cytotoxicity by hexavalent chromium released at outside and inside of cells. The cellular influences of Cr(2)O(3) nanoparticles matched those of hexavalent chromium. In conclusion, Cr(2)O(3) nanoparticles have a high cytotoxic potential.","Chromium(III) oxide nanoparticles induced remarkable oxidative stress and apoptosis on culture cells Abs: Chromium(III) oxide (Cr(2)O(3)) is used for industrial applications such as catalysts and pigments. In the classical form, namely the fine particle, Cr(2)O(3) is insoluble and chemically stable. It is classified as a low-toxicity chromium compound. Recently, industrial application of nanoparticles (a new form composed of small particles with a diameter of ?100 nm, in at least one dimension) has been increasing. Cellular effects induced by Cr(2)O(3) nanoparticles are not known. To shed light upon this, the release of soluble chromium from Cr(2)O(3) nano- and fine-particles in culture medium was compared. Fine Cr(2)O(3) particles were insoluble in the culture medium; on the contrary, Cr(2)O(3) nanoparticles released soluble hexavalent chromium into the culture medium. Cr(2)O(3) nanoparticles showed severe cytotoxicity. The effect of Cr(2)O(3) nanoparticles on cell viability was higher than that of fine particles. Cr(2)O(3) nanoparticles showed cytotoxicity equal to that of hexavalent chromium (K(2)Cr(2)O(7)). Human lung carcinoma A549 cells and human keratinocyte HaCaT cells showed an increase in intracellular reactive oxygen species (ROS) level and activation of antioxidant defense systems on exposure to Cr(2)O(3) nanoparticles. Exposure of Cr(2)O(3) nanoparticles led to caspase-3 activation, showing that the decrease in cell viability by exposure to Cr(2)O(3) nanoparticles was caused by apoptosis. Cellular responses were stronger in the Cr(2)O(3) nanoparticles-exposed cells than in fine Cr(2)O(3) - and CrCl(3) -exposed cells. Cellular uptake of Cr(2)O(3) particles were observed in nano- and fine-particles. The cellular influence of the extracellular soluble trivalent chromium was lower than that of Cr(2)O(3) nanoparticles. Cr(2)O(3) nanoparticles showed cytotoxicity by hexavalent chromium released at outside and inside of cells. The cellular influences of Cr(2)O(3) nanoparticles matched those of hexavalent chromium. In conclusion, Cr(2)O(3) nanoparticles have a high cytotoxic potential."
1509838,El-Shahawi et al. 2011,Spectrofluorometric determination and chemical speciation of trace concentrations of chromium (III &amp; VI) species in water using the ion pairing reagent tetraphenyl-phosphonium bromide,"A highly selective, and low cost extractive spectrofluorometric method has been developed for determination of trace concentrations of chromium (III &amp; VI) in water samples using the fluorescent reagent tetraphenylphosphonium bromide (TPP(+) · Br(-)). The method was based upon solvent extraction of the produced ion associate [TPP(+) · CrO(3)Cl(-)] of TPP(+) · Br(-) and halochromate in aqueous HCl and measuring the fluorescence quenching of TPP(+) · Br(-) in chloroform at ?(ex/em)=242/305 nm. The fluorescence intensity of TPP(+)Br(-) decreased linearly on increasing the chromium (VI) concentration in the range of 1-114 ?g L(-1). The limits of detection (LOD) and quantification (LOQ) of chromium (VI) were 0.43 and 1.42 ?g L(-1), respectively. Chromium (III) species after oxidation to chromium (VI) with H(2)O(2) in alkaline solution were also determined. Chemical speciation of chromium (III &amp; VI) species at trace levels was achieved. The method was applied for analysis of chromium in certified reference material (IAEA Soil-7) and in tap- and wastewater samples and compared successfully (&gt;95%) with the inductively coupled plasma-mass spectrometry (ICP-MS) results.","Spectrofluorometric determination and chemical speciation of trace concentrations of chromium (III &amp; VI) species in water using the ion pairing reagent tetraphenyl-phosphonium bromide Abs: A highly selective, and low cost extractive spectrofluorometric method has been developed for determination of trace concentrations of chromium (III &amp; VI) in water samples using the fluorescent reagent tetraphenylphosphonium bromide (TPP(+) · Br(-)). The method was based upon solvent extraction of the produced ion associate [TPP(+) · CrO(3)Cl(-)] of TPP(+) · Br(-) and halochromate in aqueous HCl and measuring the fluorescence quenching of TPP(+) · Br(-) in chloroform at ?(ex/em)=242/305 nm. The fluorescence intensity of TPP(+)Br(-) decreased linearly on increasing the chromium (VI) concentration in the range of 1-114 ?g L(-1). The limits of detection (LOD) and quantification (LOQ) of chromium (VI) were 0.43 and 1.42 ?g L(-1), respectively. Chromium (III) species after oxidation to chromium (VI) with H(2)O(2) in alkaline solution were also determined. Chemical speciation of chromium (III &amp; VI) species at trace levels was achieved. The method was applied for analysis of chromium in certified reference material (IAEA Soil-7) and in tap- and wastewater samples and compared successfully (&gt;95%) with the inductively coupled plasma-mass spectrometry (ICP-MS) results."
1509837,Zhao et al. 2009,Use of synchrotron- and plasma-based spectroscopic techniques to determine the uptake and biotransformation of chromium(III) and chromium(VI) by Parkinsonia aculeata,"In this study, a combination of inductively coupled plasma optical emission spectroscopy and X-ray absorption spectroscopy (XAS) was used to study the uptake and speciation of chromium in Parkinsonia aculeata, commonly known as Mexican Palo Verde. Plants were treated for 14 days in a modified Hoagland solution containing chromium(III) or chromium(VI) at several concentrations. The results showed that plants treated with 70 mg Cr(III) L(-1) and 30 mg Cr(VI) L(-1) had similar Cr concentrations in leaves (?200 mg kg(-1) dry weight, DW). The results also showed that neither Cr(III) nor Cr(VI) affected the uptake of phosphorus and sulfur. However, the concentration of calcium in the stems of plants treated with Cr(VI) at 40 mg L(-1) (about 6000 mg Ca kg(-1) DW) was significantly higher compared to the Ca concentration (about 3000 mg kg(-1) DW) found in the stems of plants treated with 150 mg Cr(III) L(-1). However, no differences were observed in potassium and magnesium concentrations. The iron concentration (about 1000 mg kg(-1) DW) in roots treated with 40 mg Cr(VI) L(-1) was similar to the iron concentration found in the roots of plants treated with 110 mg Cr(III) L(-1). The XAS data showed that Cr(VI) was reduced to Cr(III) in/on the plant roots and transported as Cr(III) to the stems and leaves. The XAS studies also showed that Cr(III) within plants was present as an octahedral complex.","Use of synchrotron- and plasma-based spectroscopic techniques to determine the uptake and biotransformation of chromium(III) and chromium(VI) by Parkinsonia aculeata Abs: In this study, a combination of inductively coupled plasma optical emission spectroscopy and X-ray absorption spectroscopy (XAS) was used to study the uptake and speciation of chromium in Parkinsonia aculeata, commonly known as Mexican Palo Verde. Plants were treated for 14 days in a modified Hoagland solution containing chromium(III) or chromium(VI) at several concentrations. The results showed that plants treated with 70 mg Cr(III) L(-1) and 30 mg Cr(VI) L(-1) had similar Cr concentrations in leaves (?200 mg kg(-1) dry weight, DW). The results also showed that neither Cr(III) nor Cr(VI) affected the uptake of phosphorus and sulfur. However, the concentration of calcium in the stems of plants treated with Cr(VI) at 40 mg L(-1) (about 6000 mg Ca kg(-1) DW) was significantly higher compared to the Ca concentration (about 3000 mg kg(-1) DW) found in the stems of plants treated with 150 mg Cr(III) L(-1). However, no differences were observed in potassium and magnesium concentrations. The iron concentration (about 1000 mg kg(-1) DW) in roots treated with 40 mg Cr(VI) L(-1) was similar to the iron concentration found in the roots of plants treated with 110 mg Cr(III) L(-1). The XAS data showed that Cr(VI) was reduced to Cr(III) in/on the plant roots and transported as Cr(III) to the stems and leaves. The XAS studies also showed that Cr(III) within plants was present as an octahedral complex."
1509836,Singha and  Das 2011,"Biosorption of Cr(VI) ions from aqueous solutions: kinetics, equilibrium, thermodynamics and desorption studies",Cr(VI) is a major water pollutant from industrial effluent whose concentration is to be reduced within the permissible limit. Present study reports a systematic evaluation of six different natural adsorbents for the removal of Cr(VI) from aqueous solutions in batch process. The adsorption kinetic data were best described by pseudo-second order model. The values of mass transfer coefficient for Cr(VI) adsorption indicated that the velocity of the adsorbate transport from the bulk to the solid phase was quite fast. The effective diffusivity of Cr(VI) removal for all the adsorbents were of the order of 10(-10) m(2)/s which suggested chemisorption of the process. The adsorption process was jointly controlled by film diffusion and intraparticle diffusion. Maximum monolayer adsorption capacities onto the natural adsorbents used were comparable to the other natural adsorbents used by other researchers. The thermodynamic studies and sorption energy calculation using Dubinin-Radushkevich isotherm model indicated that the adsorption processes were endothermic and chemical in nature. FT-IR studies were carried out to understand the type of functional groups responsible for Cr(VI) binding process. Desorption study was carried out with different concentration of NaOH solutions. Application study was carried out using electroplating industrial wastewater.,"Biosorption of Cr(VI) ions from aqueous solutions: kinetics, equilibrium, thermodynamics and desorption studies Abs: Cr(VI) is a major water pollutant from industrial effluent whose concentration is to be reduced within the permissible limit. Present study reports a systematic evaluation of six different natural adsorbents for the removal of Cr(VI) from aqueous solutions in batch process. The adsorption kinetic data were best described by pseudo-second order model. The values of mass transfer coefficient for Cr(VI) adsorption indicated that the velocity of the adsorbate transport from the bulk to the solid phase was quite fast. The effective diffusivity of Cr(VI) removal for all the adsorbents were of the order of 10(-10) m(2)/s which suggested chemisorption of the process. The adsorption process was jointly controlled by film diffusion and intraparticle diffusion. Maximum monolayer adsorption capacities onto the natural adsorbents used were comparable to the other natural adsorbents used by other researchers. The thermodynamic studies and sorption energy calculation using Dubinin-Radushkevich isotherm model indicated that the adsorption processes were endothermic and chemical in nature. FT-IR studies were carried out to understand the type of functional groups responsible for Cr(VI) binding process. Desorption study was carried out with different concentration of NaOH solutions. Application study was carried out using electroplating industrial wastewater."
1509835,Sharma et al. 2011,Validation and application of Drosophila melanogaster as an in vivo model for the detection of double strand breaks by neutral Comet assay,"Comet assay under neutral conditions allows detection of DNA double-strand breaks (DSBs), which has consequence to genome instability and carcinogenesis. The present study aims to validate the neutral Comet assay for genotoxicity assessment in Drosophila melanogaster (Oregon R(+)) with three well known DSBs inducers i.e. cyclophosphamide (CP), bleomycin (BLM), cisplatin (CPT) and subsequently its efficacy in detecting DSBs in the organism exposed to a well known environmental chemical, chromium [Cr(VI)]. Third instar larvae of D. melanogaster were fed different concentrations of BLM, CPT and CP (50.0-200.0?g/ml) or Cr(VI) (5.0-20.0?g/ml) mixed standard Drosophila food for 48h. Neutral Comet assay was performed in cells of mid gut and brain from control and treated larvae. Our results show a dose-dependent increase in the migration of DNA in cells of the exposed organisms. A comparison among DNA lesions per mole number of the test chemical in the exposed groups showed that both BLM and CPT induce more DSBs than CP. Interestingly, Cr(VI) at 20.0?g/ml was found to induce significantly increased (p&lt;0.001) DSBs in the exposed organism as compared to the control. The study while validating neutral Comet assay in D. melanogaster suggests its use for in vivo assessment of environmental chemical induced DSBs.","Validation and application of Drosophila melanogaster as an in vivo model for the detection of double strand breaks by neutral Comet assay Abs: Comet assay under neutral conditions allows detection of DNA double-strand breaks (DSBs), which has consequence to genome instability and carcinogenesis. The present study aims to validate the neutral Comet assay for genotoxicity assessment in Drosophila melanogaster (Oregon R(+)) with three well known DSBs inducers i.e. cyclophosphamide (CP), bleomycin (BLM), cisplatin (CPT) and subsequently its efficacy in detecting DSBs in the organism exposed to a well known environmental chemical, chromium [Cr(VI)]. Third instar larvae of D. melanogaster were fed different concentrations of BLM, CPT and CP (50.0-200.0?g/ml) or Cr(VI) (5.0-20.0?g/ml) mixed standard Drosophila food for 48h. Neutral Comet assay was performed in cells of mid gut and brain from control and treated larvae. Our results show a dose-dependent increase in the migration of DNA in cells of the exposed organisms. A comparison among DNA lesions per mole number of the test chemical in the exposed groups showed that both BLM and CPT induce more DSBs than CP. Interestingly, Cr(VI) at 20.0?g/ml was found to induce significantly increased (p&lt;0.001) DSBs in the exposed organism as compared to the control. The study while validating neutral Comet assay in D. melanogaster suggests its use for in vivo assessment of environmental chemical induced DSBs."
1509834,Mondal et al. 2011,Synthesis of polypyrrole nanoparticles and its grafting with silica gel for selective binding of chromium(VI),"Polypyrrole nanoparticles of desired structure have been synthesized through simple micelle technique. It is then grafted with functionalized silica gel to develop a novel organic-inorganic hybrid material. The role of dimethyl dichloro silane (coupling agent) in grafting is demonstrated. The nanoparticles are characterized by TEM, SEM and TGA. Grafting reactions are evaluated by spectral (FTIR) analysis and chemical test. The Cr(VI) binding behavior of the composite is studied in various pH of the medium. The selectivity in binding Cr(VI) is monitored. The metal ion adsorption capacity and surface area of the material are found to be 38 mg/g and 235 m(2)/g, respectively.","Synthesis of polypyrrole nanoparticles and its grafting with silica gel for selective binding of chromium(VI) Abs: Polypyrrole nanoparticles of desired structure have been synthesized through simple micelle technique. It is then grafted with functionalized silica gel to develop a novel organic-inorganic hybrid material. The role of dimethyl dichloro silane (coupling agent) in grafting is demonstrated. The nanoparticles are characterized by TEM, SEM and TGA. Grafting reactions are evaluated by spectral (FTIR) analysis and chemical test. The Cr(VI) binding behavior of the composite is studied in various pH of the medium. The selectivity in binding Cr(VI) is monitored. The metal ion adsorption capacity and surface area of the material are found to be 38 mg/g and 235 m(2)/g, respectively."
1509833,Idris et al. 2011,Kinetic and regeneration studies of photocatalytic magnetic separable beads for chromium (VI) reduction under sunlight,"Physical adsorption and photocatalytic reduction of Cr(VI) in magnetic separable beads were investigated. In order to elucidate the kinetics of photocatalytic process, operating parameters such as catalyst dosage and the initial concentration were examined in detail. It was observed that the reduction rate of Cr(VI) increased with an increase in the catalyst loading, as this translated into an increase in the number of available active sites. Critical scrutiny of the percentage of the initial reduction rate versus time at various initial concentration of Cr(VI) revealed that the rate of substrate conversion decreased as the initial concentration increased. The kinetic analysis of the photoreduction showed that the removal of Cr(VI) satisfactory obeyed the pseudo first-order kinetic according to the Langmuir-Hinshelwood (L-H) model and the absorption of Cr(VI) on the magnetic beads surfaces was the controlling step in the entire reduction process. Furthermore, desorption experiments by elution of the loaded gels with sodium hydroxide indicated that the magnetic photocatalyst beads could be reused without significant losses of their initial properties even after 3 adsorption-desorption cycles.","Kinetic and regeneration studies of photocatalytic magnetic separable beads for chromium (VI) reduction under sunlight Abs: Physical adsorption and photocatalytic reduction of Cr(VI) in magnetic separable beads were investigated. In order to elucidate the kinetics of photocatalytic process, operating parameters such as catalyst dosage and the initial concentration were examined in detail. It was observed that the reduction rate of Cr(VI) increased with an increase in the catalyst loading, as this translated into an increase in the number of available active sites. Critical scrutiny of the percentage of the initial reduction rate versus time at various initial concentration of Cr(VI) revealed that the rate of substrate conversion decreased as the initial concentration increased. The kinetic analysis of the photoreduction showed that the removal of Cr(VI) satisfactory obeyed the pseudo first-order kinetic according to the Langmuir-Hinshelwood (L-H) model and the absorption of Cr(VI) on the magnetic beads surfaces was the controlling step in the entire reduction process. Furthermore, desorption experiments by elution of the loaded gels with sodium hydroxide indicated that the magnetic photocatalyst beads could be reused without significant losses of their initial properties even after 3 adsorption-desorption cycles."
1509832,Anandkumar and  Mandal 2011,"Adsorption of chromium(VI) and Rhodamine B by surface modified tannery waste: kinetic, mechanistic and thermodynamic studies","In this study, various activation methods have been employed to examine the potential reuse of tannery residual biomass (TRB) obtained from vegetable tanning process for the removal of Cr(VI) and Rhodamine B (RB) from aqueous solution. The maximum BET surface area (10.42 m(2)/g), honey comb pore distribution and uptake of both Cr(VI) and RB were achieved when only 3-fold volume of HCl was used to activate the biomass. The pH and temperature experiment showed that they have considerable impact on the adsorption capacity of the used adsorbent. The presence of other ions (Na(+), Ca(2+) and NH(4)(+)) significantly reduces the metal uptake but marginal enhancement in the dye removal was observed when Na(+) and NH(4)(+) ions were present in the solution. The equilibrium data fitted satisfactorily with the Langmuir model and monolayer sorption capacity obtained as 177-217 and 213-250 mg/g for Cr(VI) and RB at 30-50°C, respectively. The sorption kinetics was found to follow the pseudo-second-order kinetic model. The increase in adsorption capacity for both metal and dye with increase in temperature indicates that the uptake was endothermic in nature. The results indicate that the HCl modified TRB (A-TRB) could be employed as a low cost adsorbent for the removal of both Cr(VI) and RB from the aqueous solution including industrial wastewater.","Adsorption of chromium(VI) and Rhodamine B by surface modified tannery waste: kinetic, mechanistic and thermodynamic studies Abs: In this study, various activation methods have been employed to examine the potential reuse of tannery residual biomass (TRB) obtained from vegetable tanning process for the removal of Cr(VI) and Rhodamine B (RB) from aqueous solution. The maximum BET surface area (10.42 m(2)/g), honey comb pore distribution and uptake of both Cr(VI) and RB were achieved when only 3-fold volume of HCl was used to activate the biomass. The pH and temperature experiment showed that they have considerable impact on the adsorption capacity of the used adsorbent. The presence of other ions (Na(+), Ca(2+) and NH(4)(+)) significantly reduces the metal uptake but marginal enhancement in the dye removal was observed when Na(+) and NH(4)(+) ions were present in the solution. The equilibrium data fitted satisfactorily with the Langmuir model and monolayer sorption capacity obtained as 177-217 and 213-250 mg/g for Cr(VI) and RB at 30-50°C, respectively. The sorption kinetics was found to follow the pseudo-second-order kinetic model. The increase in adsorption capacity for both metal and dye with increase in temperature indicates that the uptake was endothermic in nature. The results indicate that the HCl modified TRB (A-TRB) could be employed as a low cost adsorbent for the removal of both Cr(VI) and RB from the aqueous solution including industrial wastewater."
1509831,Mathur et al. 2010,Removal of chromium by some multipurpose tree seedlings of Indian thar desert,"An experiment was conducted to study the potential of chromium (Cr) phytoaccumulatory capabilities of four tree species viz., Anogeissus latifolia, Terminalia arjuna, Tecomella undulata, and Salvadora persica Possibility of enhancement of Cr uptake by citric acid and vesicular arbuscular mycorrhizal fungi (VAM) amendments were also tried. Cr is a major pollutant of the environment. Chromium can exist in oxidation states from III to VI, but the most stable and common forms of Cr are trivalent and hexavalent species. Cr(VI) was more toxic to the tree growth in terms of collar diameter (CD) increment in all the tree species than Cr(lll). Roots accumulated more Cr than shoots in all the tree species. There was more than 10 fold increase in root Cr content in comparison with shoot Cr content in all the trees at all the concentration of Cr and all sources of Cr. Citric acid significantly increased the Cr content in the tissues of roots in all the species under both speciation of Cr. The highest increase in Cr content brought by 20 mM citric acid addition was in A. latifolia Results suggest that Anogeissus latifolia is a potential Cr accumulator with citric acid as soil amendment.","Removal of chromium by some multipurpose tree seedlings of Indian thar desert Abs: An experiment was conducted to study the potential of chromium (Cr) phytoaccumulatory capabilities of four tree species viz., Anogeissus latifolia, Terminalia arjuna, Tecomella undulata, and Salvadora persica Possibility of enhancement of Cr uptake by citric acid and vesicular arbuscular mycorrhizal fungi (VAM) amendments were also tried. Cr is a major pollutant of the environment. Chromium can exist in oxidation states from III to VI, but the most stable and common forms of Cr are trivalent and hexavalent species. Cr(VI) was more toxic to the tree growth in terms of collar diameter (CD) increment in all the tree species than Cr(lll). Roots accumulated more Cr than shoots in all the tree species. There was more than 10 fold increase in root Cr content in comparison with shoot Cr content in all the trees at all the concentration of Cr and all sources of Cr. Citric acid significantly increased the Cr content in the tissues of roots in all the species under both speciation of Cr. The highest increase in Cr content brought by 20 mM citric acid addition was in A. latifolia Results suggest that Anogeissus latifolia is a potential Cr accumulator with citric acid as soil amendment."
1509830,Le et al. 2010,Synthesis of chromium-doped malayaite pigments from wastewater containing low chromium(VI),"A malayaite pigment was synthesized with wastewater containing low chromium (Cr)(VI) by a novel liquid-phase reaction method. The effects of the particle size of the precursor and calcination temperature on the final product are examined. The result of scanning electron microscopy shows that the obtained precursor is amorphous and the particle size is approximately 250 nm. The results of X-ray diffraction and differential scanning calorimetry show that the complete transformation temperature was approximately 1050 degrees C. Furthermore, the Commission International de l'Eclairage laboratory shows that the red color of as-prepared pigments is more saturated with a high a* value at 34.1. This process of malayaite pigment preparation via reuse of the Cr(VI)-containing wastewater is quite simple, economical, and energy-saving for the industry, and the products have a saturated red color. There is considerable foreground for the industrial application of this work.","Synthesis of chromium-doped malayaite pigments from wastewater containing low chromium(VI) Abs: A malayaite pigment was synthesized with wastewater containing low chromium (Cr)(VI) by a novel liquid-phase reaction method. The effects of the particle size of the precursor and calcination temperature on the final product are examined. The result of scanning electron microscopy shows that the obtained precursor is amorphous and the particle size is approximately 250 nm. The results of X-ray diffraction and differential scanning calorimetry show that the complete transformation temperature was approximately 1050 degrees C. Furthermore, the Commission International de l'Eclairage laboratory shows that the red color of as-prepared pigments is more saturated with a high a* value at 34.1. This process of malayaite pigment preparation via reuse of the Cr(VI)-containing wastewater is quite simple, economical, and energy-saving for the industry, and the products have a saturated red color. There is considerable foreground for the industrial application of this work."
1509829,Malarvizhi et al. 2010,Studies on removal of chromium (VI) from water using chitosan coated Cyperus pangorei,"Environmental contamination by toxic heavy metals is a significant universal problem. The main objective of the study is to use a biodegradable materials like Cyperus pangorei and Chitosan as a composite biosorbent for the removal of Cr(VI) from water. The newly prepared biosorbent is characterized and the capacity of Cr(VI) removal of the biosorbent is carried out systematically by batch mode operations. The adsorption capacity of the biosorbent is examined by changing the parameters like biosorbent dose, varying the initial contact time, varying initial concentration of metal ion and pH of the metal ion solution to know the actual mechanism taking place during the initial sorption process. The experimental data obtained were fitted with the Freundlich, Langmuir and Redlich-Peterson isotherm models and the pseudo first order and the pseudo second order kinetic models. Equilibrium data were fitted very well to the Langmuir Isotherm model and pseudo second order kinetic model. Desorption of the metal ion is also carried out using different concentration of NaOH.","Studies on removal of chromium (VI) from water using chitosan coated Cyperus pangorei Abs: Environmental contamination by toxic heavy metals is a significant universal problem. The main objective of the study is to use a biodegradable materials like Cyperus pangorei and Chitosan as a composite biosorbent for the removal of Cr(VI) from water. The newly prepared biosorbent is characterized and the capacity of Cr(VI) removal of the biosorbent is carried out systematically by batch mode operations. The adsorption capacity of the biosorbent is examined by changing the parameters like biosorbent dose, varying the initial contact time, varying initial concentration of metal ion and pH of the metal ion solution to know the actual mechanism taking place during the initial sorption process. The experimental data obtained were fitted with the Freundlich, Langmuir and Redlich-Peterson isotherm models and the pseudo first order and the pseudo second order kinetic models. Equilibrium data were fitted very well to the Langmuir Isotherm model and pseudo second order kinetic model. Desorption of the metal ion is also carried out using different concentration of NaOH."
1509828,Döker et al. 2010,Probing the metal-homeostatis effects of the administration of chromium(vi) to mice by ICP MS and size-exclusion chromatography-ICP MS,"Concentrations of chromium, copper, iron, manganese and zinc were determined in liver, kidney, brain, lung, heart and testis of mouse following intraperitoneal injection of hexavalent chromium [Cr(vi)] at a single dose of 8.0 mg Cr/kg. As result, chromium concentrations increased ca. 40-fold in liver and kidney and by a factor of 3-5 in all the other tissues. The homeostasis of Cu, Fe, Mn and Zn was also affected. The element molecular weight distribution was evaluated in the cytosols of the different mouse organs by size-exclusion chromatography (Superdex-75) with UV-VIS and ICP-MS detection. The administration of Cr(vi) resulted in differences in the elution profiles of Fe, Mn, Cu and Zn-protein complexes. Bioinduced Mn, Fe and Zn-binding proteins could be detected in some tissues, especially in liver and kidney. Different molecular weight fractions containing chromium were heartcut and submitted to tryptic digestion prior to MALDI MS analysis. Cr-peptide complexes could be obtained both in non-denaturing and in denaturing (in the presence of urea and DTT) conditions. They were isolated by size-exclusion chromatography with a smaller separation range (Superdex Peptide) but could not be identified by MALDI MS.","Probing the metal-homeostatis effects of the administration of chromium(vi) to mice by ICP MS and size-exclusion chromatography-ICP MS Abs: Concentrations of chromium, copper, iron, manganese and zinc were determined in liver, kidney, brain, lung, heart and testis of mouse following intraperitoneal injection of hexavalent chromium [Cr(vi)] at a single dose of 8.0 mg Cr/kg. As result, chromium concentrations increased ca. 40-fold in liver and kidney and by a factor of 3-5 in all the other tissues. The homeostasis of Cu, Fe, Mn and Zn was also affected. The element molecular weight distribution was evaluated in the cytosols of the different mouse organs by size-exclusion chromatography (Superdex-75) with UV-VIS and ICP-MS detection. The administration of Cr(vi) resulted in differences in the elution profiles of Fe, Mn, Cu and Zn-protein complexes. Bioinduced Mn, Fe and Zn-binding proteins could be detected in some tissues, especially in liver and kidney. Different molecular weight fractions containing chromium were heartcut and submitted to tryptic digestion prior to MALDI MS analysis. Cr-peptide complexes could be obtained both in non-denaturing and in denaturing (in the presence of urea and DTT) conditions. They were isolated by size-exclusion chromatography with a smaller separation range (Superdex Peptide) but could not be identified by MALDI MS."
1509827,Shi et al. 2011,Removal of chromium (VI) from wastewater using bentonite-supported nanoscale zero-valent iron,"Bentonite-supported nanoscale zero-valent iron (B-nZVI) was synthesized using liquid-phase reduction. The orthogonal method was used to evaluate the factors impacting Cr(VI) removal and this showed that the initial concentration of Cr(VI), pH, temperature, and B-nZVI loading were all importance factors. Characterization with scanning electron microscopy (SEM) validated the hypothesis that the presence of bentonite led to a decrease in aggregation of iron nanoparticles and a corresponding increase in the specific surface area (SSA) of the iron particles. B-nZVI with a 50% bentonite mass fraction had a SSA of 39.94 m(2)/g, while the SSA of nZVI and bentonite was 54.04 and 6.03 m(2)/g, respectively. X-ray diffraction (XRD) confirmed the existence of Fe(0) before the reaction and the presence of Fe(II), Fe(III) and Cr(III) after the reaction. Batch experiments revealed that the removal of Cr (VI) using B-nZVI was consistent with pseudo first-order reaction kinetics. Finally, B-nZVI was used to remediate electroplating wastewater with removal efficiencies for Cr, Pb and Cu &gt; 90%. Reuse of B-nZVI after washing with ethylenediaminetetraacetic acid (EDTA) solution was possible but the capacity of B-nZVI for Cr(VI) removal decreased by approximately 70%.","Removal of chromium (VI) from wastewater using bentonite-supported nanoscale zero-valent iron Abs: Bentonite-supported nanoscale zero-valent iron (B-nZVI) was synthesized using liquid-phase reduction. The orthogonal method was used to evaluate the factors impacting Cr(VI) removal and this showed that the initial concentration of Cr(VI), pH, temperature, and B-nZVI loading were all importance factors. Characterization with scanning electron microscopy (SEM) validated the hypothesis that the presence of bentonite led to a decrease in aggregation of iron nanoparticles and a corresponding increase in the specific surface area (SSA) of the iron particles. B-nZVI with a 50% bentonite mass fraction had a SSA of 39.94 m(2)/g, while the SSA of nZVI and bentonite was 54.04 and 6.03 m(2)/g, respectively. X-ray diffraction (XRD) confirmed the existence of Fe(0) before the reaction and the presence of Fe(II), Fe(III) and Cr(III) after the reaction. Batch experiments revealed that the removal of Cr (VI) using B-nZVI was consistent with pseudo first-order reaction kinetics. Finally, B-nZVI was used to remediate electroplating wastewater with removal efficiencies for Cr, Pb and Cu &gt; 90%. Reuse of B-nZVI after washing with ethylenediaminetetraacetic acid (EDTA) solution was possible but the capacity of B-nZVI for Cr(VI) removal decreased by approximately 70%."
1509826,Morton-Bermea et al. 2010,"Spatial distribution of heavy metals in top soils around the industrial facilities of Cromatos de México, Tultitlan Mexico","The environmental damage caused by industrial activities in Cromatos de México, (Tultitlán, México) has been evaluated in terms of heavy metal concentrations in topsoils of the surrounding area. The concentrations of lead, copper and zinc demonstrate a significant enrichment with respect to unpolluted levels. Their maximum enrichment factors are 37.7, 21.1 and 9.6 mg kg?¹, respectively; such increase is related to traffic emissions. Nickel concentrations show no significant difference in the analyzed samples. Total chromium concentrations show a significant decrease with distance from the industrial facilities, ranging from 15 to 1,837 mg kg?¹. The enrichment factors of chromium (total), with respect to the background values reach up to 40.8 mg kg?¹. In spite of this pronounced increase, only three analyzed samples show chromium (VI) concentrations over 0.5 mg kg?¹ (instrumental detection limit) and do not exceed the values recommended by the Mexican official norm. The current results show that the chromium present in the studied area does not represent serious health risks and environmental damage in the zone, nevertheless, it is necessary to consider that the oxidation of chromium (III) is determinate by changes in redox and/or pH conditions which would imply significant impacts upon its toxic risk. This study suggests that the waste material generated during the industrial activities of Cromatos de Mexico represents a relevant metal pollution source for the area even 30 years after the closure of the industrial facilities.","Spatial distribution of heavy metals in top soils around the industrial facilities of Cromatos de México, Tultitlan Mexico Abs: The environmental damage caused by industrial activities in Cromatos de México, (Tultitlán, México) has been evaluated in terms of heavy metal concentrations in topsoils of the surrounding area. The concentrations of lead, copper and zinc demonstrate a significant enrichment with respect to unpolluted levels. Their maximum enrichment factors are 37.7, 21.1 and 9.6 mg kg?¹, respectively; such increase is related to traffic emissions. Nickel concentrations show no significant difference in the analyzed samples. Total chromium concentrations show a significant decrease with distance from the industrial facilities, ranging from 15 to 1,837 mg kg?¹. The enrichment factors of chromium (total), with respect to the background values reach up to 40.8 mg kg?¹. In spite of this pronounced increase, only three analyzed samples show chromium (VI) concentrations over 0.5 mg kg?¹ (instrumental detection limit) and do not exceed the values recommended by the Mexican official norm. The current results show that the chromium present in the studied area does not represent serious health risks and environmental damage in the zone, nevertheless, it is necessary to consider that the oxidation of chromium (III) is determinate by changes in redox and/or pH conditions which would imply significant impacts upon its toxic risk. This study suggests that the waste material generated during the industrial activities of Cromatos de Mexico represents a relevant metal pollution source for the area even 30 years after the closure of the industrial facilities."
1509825,Morel et al. 2011,Delftia sp. JD2: a potential Cr(VI)-reducing agent with plant growth-promoting activity,"A chromium (Cr)-resistant bacterium isolated from soil containing 6,000 mg/kg of Cr was identified based on 16S rRNA gene sequence analysis as Delftia, and designated as JD2. Growth of JD2 was accompanied with reduction of Cr(VI) to Cr(III) in liquid medium initially containing 100 mg/L Cr(VI), the maximum concentration allowing growth. JD2 showed NADH/NADPH-dependent reductase activity associated with the soluble fraction of cells. The results suggest that JD2 might be a good candidate for the treatment of highly Cr(VI)-contaminated water and/or industrial effluents. The isolate produced indole-3-acetic acid in the presence and absence of Cr(VI) and showed free-living nitrogen-fixing activity possibly attributable to a V-nitrogenase. JD2 did not counteract the harmful effect of Cr(VI) during leguminous plant growth and nodulation by rhizobial strains but functioned as a &quot;helper&quot; bacterium to enhance the performance of rhizobial inoculant strains during inoculation of alfalfa and clover (used as model plants to study plant growth-promoting activity) in the absence of Cr(VI).","Delftia sp. JD2: a potential Cr(VI)-reducing agent with plant growth-promoting activity Abs: A chromium (Cr)-resistant bacterium isolated from soil containing 6,000 mg/kg of Cr was identified based on 16S rRNA gene sequence analysis as Delftia, and designated as JD2. Growth of JD2 was accompanied with reduction of Cr(VI) to Cr(III) in liquid medium initially containing 100 mg/L Cr(VI), the maximum concentration allowing growth. JD2 showed NADH/NADPH-dependent reductase activity associated with the soluble fraction of cells. The results suggest that JD2 might be a good candidate for the treatment of highly Cr(VI)-contaminated water and/or industrial effluents. The isolate produced indole-3-acetic acid in the presence and absence of Cr(VI) and showed free-living nitrogen-fixing activity possibly attributable to a V-nitrogenase. JD2 did not counteract the harmful effect of Cr(VI) during leguminous plant growth and nodulation by rhizobial strains but functioned as a &quot;helper&quot; bacterium to enhance the performance of rhizobial inoculant strains during inoculation of alfalfa and clover (used as model plants to study plant growth-promoting activity) in the absence of Cr(VI)."
1509824,Recillas et al. 2010,Chromium VI adsorption on cerium oxide nanoparticles and morphology changes during the process,"In this study, suspended cerium oxide nanoparticles stabilized with hexamethylenetetramine were used for the removal of dissolved chromium VI in pure water. Several concentrations of adsorbent and adsorbate were tested, trying to cover a large range of possible real conditions. Results showed that the Freundlich isotherm represented well the adsorption equilibrium reached between nanoparticles and chromium, whereas adsorption kinetics could be modeled by a pseudo-second-order expression. The separation of chromium-cerium nanoparticles from the medium and the desorption of chromium using sodium hydroxide without cerium losses was obtained. Nanoparticles agglomeration and morphological changes during the adsorption-desorption process were observed by TEM. Another remarkable result obtained in this study is the low toxicity in the water treated by nanoparticles measured by the Microtox(®) commercial method. These results can be used to propose this treatment sequence for a clean and simple removal of drinking water or wastewater re-use when a high toxicity heavy metal such as chromium VI is the responsible for water pollution.","Chromium VI adsorption on cerium oxide nanoparticles and morphology changes during the process Abs: In this study, suspended cerium oxide nanoparticles stabilized with hexamethylenetetramine were used for the removal of dissolved chromium VI in pure water. Several concentrations of adsorbent and adsorbate were tested, trying to cover a large range of possible real conditions. Results showed that the Freundlich isotherm represented well the adsorption equilibrium reached between nanoparticles and chromium, whereas adsorption kinetics could be modeled by a pseudo-second-order expression. The separation of chromium-cerium nanoparticles from the medium and the desorption of chromium using sodium hydroxide without cerium losses was obtained. Nanoparticles agglomeration and morphological changes during the adsorption-desorption process were observed by TEM. Another remarkable result obtained in this study is the low toxicity in the water treated by nanoparticles measured by the Microtox(®) commercial method. These results can be used to propose this treatment sequence for a clean and simple removal of drinking water or wastewater re-use when a high toxicity heavy metal such as chromium VI is the responsible for water pollution."
1509823,Gheju and  Balcu 2010,Hexavalent chromium reduction with scrap iron in continuous-flow system. Part 2: Effect of scrap iron shape and size,"Hexavalent chromium reduction with scrap iron has the advantage that two wastes are treated simultaneously. The reduction of hexavalent chromium by scrap iron was investigated in continuous system, using as reducing agent the following scrap iron shapes and sizes: (1) spiral fibers, (2) shavings, and (3) powder. The shape and size of scrap iron were found to have a significant influence on chromium and iron species concentration in column effluent, on column effluent pH and on Cr(VI) reduction mechanism. While for large scrap iron particles (spiral fibers) homogeneous reduction is the dominant Cr(VI) reduction process, for small scrap iron particles (powder) heterogeneous reduction appears to be the dominant reaction contributing to Cr(VI) reduction. All three shapes and sizes investigated in this work have both advantages and disadvantages. If found in sufficient quantities, scrap iron powder seem to be the optimum shape and size for the continuous reduction of Cr(VI), due to the following advantages: (1) the greatest reduction capacity, (2) the most important pH increase in column effluent (up to 6.3), (3) no chromium was detected in the column effluent during the first 60 h of the experiment, and (4) the lowest steady-state Cr(VI) concentration observed in column effluent (3.7 mg/L). But, despite of a lower reduction capacity in comparison with powder particles, spiral fibers and shavings have the advantage to result in large quantities from the mechanic processing of steel.","Hexavalent chromium reduction with scrap iron in continuous-flow system. Part 2: Effect of scrap iron shape and size Abs: Hexavalent chromium reduction with scrap iron has the advantage that two wastes are treated simultaneously. The reduction of hexavalent chromium by scrap iron was investigated in continuous system, using as reducing agent the following scrap iron shapes and sizes: (1) spiral fibers, (2) shavings, and (3) powder. The shape and size of scrap iron were found to have a significant influence on chromium and iron species concentration in column effluent, on column effluent pH and on Cr(VI) reduction mechanism. While for large scrap iron particles (spiral fibers) homogeneous reduction is the dominant Cr(VI) reduction process, for small scrap iron particles (powder) heterogeneous reduction appears to be the dominant reaction contributing to Cr(VI) reduction. All three shapes and sizes investigated in this work have both advantages and disadvantages. If found in sufficient quantities, scrap iron powder seem to be the optimum shape and size for the continuous reduction of Cr(VI), due to the following advantages: (1) the greatest reduction capacity, (2) the most important pH increase in column effluent (up to 6.3), (3) no chromium was detected in the column effluent during the first 60 h of the experiment, and (4) the lowest steady-state Cr(VI) concentration observed in column effluent (3.7 mg/L). But, despite of a lower reduction capacity in comparison with powder particles, spiral fibers and shavings have the advantage to result in large quantities from the mechanic processing of steel."
1509822,Aranda et al. 2010,Determination of trace chromium(VI) in drinking water using X-ray fluorescence spectrometry after solid-phase extraction,"A new, simple, and selective method for preconcentration and determination of Cr(VI) in aqueous samples. After adsorption in &quot;batch mode&quot; on Aliquat 336-AC, determinations were made directly on the solid by X-ray fluorescence spectrometry, which had the advantage of not requiring the step of elution of the chromium retained. The enrichment factor was calculated considering that the tablets obtained from 10 mL solution of Cr(VI) (1000 ?g?L(-1)) had a final thickness of 0.64 mm and a diameter of 16.7 mm; the volume deposited on the pellet was 0.14 cm(3). The preconcentration factor obtained was 71-fold, which was highly satisfactory for chromium trace analysis by XRF. Finally, the method was successfully applied to the determination of Cr(VI) in drinking water samples.","Determination of trace chromium(VI) in drinking water using X-ray fluorescence spectrometry after solid-phase extraction Abs: A new, simple, and selective method for preconcentration and determination of Cr(VI) in aqueous samples. After adsorption in &quot;batch mode&quot; on Aliquat 336-AC, determinations were made directly on the solid by X-ray fluorescence spectrometry, which had the advantage of not requiring the step of elution of the chromium retained. The enrichment factor was calculated considering that the tablets obtained from 10 mL solution of Cr(VI) (1000 ?g?L(-1)) had a final thickness of 0.64 mm and a diameter of 16.7 mm; the volume deposited on the pellet was 0.14 cm(3). The preconcentration factor obtained was 71-fold, which was highly satisfactory for chromium trace analysis by XRF. Finally, the method was successfully applied to the determination of Cr(VI) in drinking water samples."
1509821,Beneito-Cambra et al. 2010,Chromium(VI) oxide oxidation of non-ethoxylated and ethoxylated alcohols for determination by electrospray ionization mass spectrometry,"A new derivatization procedure to increase the sensitivity of electrospray ionization mass spectrometry (ESI-MS) to non-ethoxylated and ethoxylated alcohols was investigated. The analytes were oxidized with chromium(VI) oxide and the resulting carboxylic and ethoxy-carboxylic acids were isolated by extraction with ethyl acetate; the extracts were alkalinized and infused into the ESI-MS system working in the negative-ion mode. The yields of the combined oxidation-extraction were ca. 100% for non-ethoxylated fatty alcohols dissolved in acetone and they decreased moderately in samples containing increasing amounts of water (e.g., a 75% yield was obtained with 50% water). Ethoxylated alcohols with more than two ethylene oxide units resulted in yields of ca. 60%. Low limits of detection (LODs) were obtained when the procedure was applied to the analysis of body-care products and cosmetics containing fatty alcohols, e.g., in a varicose-vein cream, the LODs were 25 microg cetyl alcohol and 7.5 microg stearyl alcohol (detected as palmitic acid and stearic acid, respectively) per gram of sample. High molecular mass alcohols were also detected in seawater after pre-concentration by solid-phase extraction. Thus, the proposed method is particularly valuable for use in industrial samples having complex matrices and in environmental samples and it is competitive with other methods for the analysis of trace amounts of fatty alcohols.","Chromium(VI) oxide oxidation of non-ethoxylated and ethoxylated alcohols for determination by electrospray ionization mass spectrometry Abs: A new derivatization procedure to increase the sensitivity of electrospray ionization mass spectrometry (ESI-MS) to non-ethoxylated and ethoxylated alcohols was investigated. The analytes were oxidized with chromium(VI) oxide and the resulting carboxylic and ethoxy-carboxylic acids were isolated by extraction with ethyl acetate; the extracts were alkalinized and infused into the ESI-MS system working in the negative-ion mode. The yields of the combined oxidation-extraction were ca. 100% for non-ethoxylated fatty alcohols dissolved in acetone and they decreased moderately in samples containing increasing amounts of water (e.g., a 75% yield was obtained with 50% water). Ethoxylated alcohols with more than two ethylene oxide units resulted in yields of ca. 60%. Low limits of detection (LODs) were obtained when the procedure was applied to the analysis of body-care products and cosmetics containing fatty alcohols, e.g., in a varicose-vein cream, the LODs were 25 microg cetyl alcohol and 7.5 microg stearyl alcohol (detected as palmitic acid and stearic acid, respectively) per gram of sample. High molecular mass alcohols were also detected in seawater after pre-concentration by solid-phase extraction. Thus, the proposed method is particularly valuable for use in industrial samples having complex matrices and in environmental samples and it is competitive with other methods for the analysis of trace amounts of fatty alcohols."
1509820,Shukor et al. 2010,Hexavalent molybdenum reduction to Mo-blue by Acinetobacter calcoaceticus,"A local molybdenum-reducing bacterium was isolated and tentatively identified as Acinetobacter calcoaceticus strain Dr.Y12 based on carbon utilization profiles using Biolog GN plates and 16S rDNA comparative analysis. Molybdate reduction was optimized under conditions of low dissolved oxygen (37 degrees C and pH 6.5). Of the electron donors tested, glucose, fructose, maltose and sucrose supported molybdate reduction after 1 d of incubation, glucose and fructose supporting the highest Mo-blue production. Optimum Mo-blue production was reached at 20 mmol/L molybdate and 5 mmol/L phosphate; increasing the phosphate concentrations inhibited the production. An increase in an overall absorption profiles, especially at peak maximum at 865 nm and the shoulder at 700 nm, was observed in direct correlation with the increased in Mo-blue amounts. Metal ions, such as chromium, cadmium, copper, mercury and lead (2 mmol/L final concentration) caused approximately 88, 53, 80, 100, and 20 % inhibition, respectively. Respiratory inhibitors, such as antimycin A, rotenone, sodium azide and cyanide showed in this bacterium no inhibition of the Mo-blue production, suggesting that the electron transport system is not a site of molybdate reduction.","Hexavalent molybdenum reduction to Mo-blue by Acinetobacter calcoaceticus Abs: A local molybdenum-reducing bacterium was isolated and tentatively identified as Acinetobacter calcoaceticus strain Dr.Y12 based on carbon utilization profiles using Biolog GN plates and 16S rDNA comparative analysis. Molybdate reduction was optimized under conditions of low dissolved oxygen (37 degrees C and pH 6.5). Of the electron donors tested, glucose, fructose, maltose and sucrose supported molybdate reduction after 1 d of incubation, glucose and fructose supporting the highest Mo-blue production. Optimum Mo-blue production was reached at 20 mmol/L molybdate and 5 mmol/L phosphate; increasing the phosphate concentrations inhibited the production. An increase in an overall absorption profiles, especially at peak maximum at 865 nm and the shoulder at 700 nm, was observed in direct correlation with the increased in Mo-blue amounts. Metal ions, such as chromium, cadmium, copper, mercury and lead (2 mmol/L final concentration) caused approximately 88, 53, 80, 100, and 20 % inhibition, respectively. Respiratory inhibitors, such as antimycin A, rotenone, sodium azide and cyanide showed in this bacterium no inhibition of the Mo-blue production, suggesting that the electron transport system is not a site of molybdate reduction."
1509819,Abida et al. 2010,Photoinduced reduction of chromium(VI) by iron aminopolycarboxylate complex (FeNTA),"Chromium(VI) reduction photoinduced by iron(III) nitrilotriacetate (FeNTA) was investigated under monochromatic excitation. 313 nm was used as the irradiation wavelength in order to minimize the absorption of the light by chromium(VI): 91% of the photons were absorbed by FeNTA at pH = 7.0. Quantum yields of FeNTA and chromium(VI) disappearance and iron(II) formation were measured at pH 2.0, 4.0 and 7.0. In all the cases, chromium(VI) reduction follows first order kinetics with maximum efficiency at pH 2.0. The observed rate constant is proportional to FeNTA concentrations up to a maximum of 6.0 x 10(-4) mol L(-1). The effect of oxygen was also investigated. If there is no large pH effect and no effect of oxygen on the quantum yields of chromium(VI) and FeNTA disappearance, the pH strongly influences the nature of the reduced chromium species. At pH 2.0, only chromium(III) was detected, whereas at pH 4.0 and 7.0 no chromium(III) resulting from chromium(VI) reduction was observed. Chromium(V) is supposed to be formed and stabilized by the chelating groups of NTA or NTA photoproducts.","Photoinduced reduction of chromium(VI) by iron aminopolycarboxylate complex (FeNTA) Abs: Chromium(VI) reduction photoinduced by iron(III) nitrilotriacetate (FeNTA) was investigated under monochromatic excitation. 313 nm was used as the irradiation wavelength in order to minimize the absorption of the light by chromium(VI): 91% of the photons were absorbed by FeNTA at pH = 7.0. Quantum yields of FeNTA and chromium(VI) disappearance and iron(II) formation were measured at pH 2.0, 4.0 and 7.0. In all the cases, chromium(VI) reduction follows first order kinetics with maximum efficiency at pH 2.0. The observed rate constant is proportional to FeNTA concentrations up to a maximum of 6.0 x 10(-4) mol L(-1). The effect of oxygen was also investigated. If there is no large pH effect and no effect of oxygen on the quantum yields of chromium(VI) and FeNTA disappearance, the pH strongly influences the nature of the reduced chromium species. At pH 2.0, only chromium(III) was detected, whereas at pH 4.0 and 7.0 no chromium(III) resulting from chromium(VI) reduction was observed. Chromium(V) is supposed to be formed and stabilized by the chelating groups of NTA or NTA photoproducts."
1509818,Lindström et al. 2010,Chromium(III) and chromium(VI) surface treated galvanized steel for outdoor constructions: environmental aspects,"The long-term degradation of chromium(III) (Zn-Cr(III)) and chromium(VI)-based (Zn-Cr(VI)) surface treatments on galvanized steel and their capacities to hinder the release of zinc induced by atmospheric corrosion at nonsheltered urban and marine exposure conditions for 2 years are investigated. Compared to bare zinc sheet, both surface treatments revealed high corrosion protection abilities and capacities to hinder the release of zinc, still evident after 2 years of exposure. The zinc barrier properties of the thinner Zn-Cr(VI) (10 nm) treatment were during the first 100 days of urban exposure slightly improved compared with Zn-Cr(III) (35 nm). However, their long-term protection capacities were inverse. Released concentrations of total chromium correspond to annual release rates less than 0.000032 (Zn-Cr(III)) and 0.00014 g Cr m(-2) yr(-1) (Zn-Cr(VI)) after 1 year of urban exposure. Aging by indoor storage of the surface treatments prior to outdoor exposure reduced the released Cr concentrations from the surface treatments. No Cr(VI) was released from the aged surfaces but from the freshly exposed Zn-Cr(VI). Marine exposure conditions resulted in a faster reduction of chromate to chromium(III)oxide compared with urban conditions, and a significantly lower amount of both chromium(III) and chromium(VI) released from Zn-Cr(VI) at the marine site compared with the urban site.","Chromium(III) and chromium(VI) surface treated galvanized steel for outdoor constructions: environmental aspects Abs: The long-term degradation of chromium(III) (Zn-Cr(III)) and chromium(VI)-based (Zn-Cr(VI)) surface treatments on galvanized steel and their capacities to hinder the release of zinc induced by atmospheric corrosion at nonsheltered urban and marine exposure conditions for 2 years are investigated. Compared to bare zinc sheet, both surface treatments revealed high corrosion protection abilities and capacities to hinder the release of zinc, still evident after 2 years of exposure. The zinc barrier properties of the thinner Zn-Cr(VI) (10 nm) treatment were during the first 100 days of urban exposure slightly improved compared with Zn-Cr(III) (35 nm). However, their long-term protection capacities were inverse. Released concentrations of total chromium correspond to annual release rates less than 0.000032 (Zn-Cr(III)) and 0.00014 g Cr m(-2) yr(-1) (Zn-Cr(VI)) after 1 year of urban exposure. Aging by indoor storage of the surface treatments prior to outdoor exposure reduced the released Cr concentrations from the surface treatments. No Cr(VI) was released from the aged surfaces but from the freshly exposed Zn-Cr(VI). Marine exposure conditions resulted in a faster reduction of chromate to chromium(III)oxide compared with urban conditions, and a significantly lower amount of both chromium(III) and chromium(VI) released from Zn-Cr(VI) at the marine site compared with the urban site."
1509817,Miretzky and  Cirelli 2010,Cr(VI) and Cr(III) removal from aqueous solution by raw and modified lignocellulosic materials: a review,"In aqueous systems, chromium usually exists in both trivalent and hexavalent oxidation states, being Cr(VI) of particular importance and concern due to its great toxicity. Industrial sources of Cr(VI) are leather tanning, mining of chrome ore, production of steel and alloys, etc. The most common conventional method for Cr(VI) removal is reduction to Cr(III) at pH 2.0 and precipitation of Cr (OH)(3) with lime at pH 9-10. The disadvantage of precipitation is the disposal of the solid waste. Adsorption of Cr by different low cost materials seems to be a suitable choice for wastewater treatment. Many by-products of agriculture have proved to be suitable low cost adsorbents for Cr(VI) and Cr(III) removal from water. Lignocellulosic residues, which include both wood residues and agricultural residues, have adsorption capacity comparable to other natural sorbents, but they have the advantage of very low or no cost, great availability and simple operational process. This study is a review of the recent literature on the use of natural and modified lignocellulosic residues for Cr adsorption. The Cr maximum adsorption capacity and the adsorption mechanism under different experimental conditions are reported when possibly.","Cr(VI) and Cr(III) removal from aqueous solution by raw and modified lignocellulosic materials: a review Abs: In aqueous systems, chromium usually exists in both trivalent and hexavalent oxidation states, being Cr(VI) of particular importance and concern due to its great toxicity. Industrial sources of Cr(VI) are leather tanning, mining of chrome ore, production of steel and alloys, etc. The most common conventional method for Cr(VI) removal is reduction to Cr(III) at pH 2.0 and precipitation of Cr (OH)(3) with lime at pH 9-10. The disadvantage of precipitation is the disposal of the solid waste. Adsorption of Cr by different low cost materials seems to be a suitable choice for wastewater treatment. Many by-products of agriculture have proved to be suitable low cost adsorbents for Cr(VI) and Cr(III) removal from water. Lignocellulosic residues, which include both wood residues and agricultural residues, have adsorption capacity comparable to other natural sorbents, but they have the advantage of very low or no cost, great availability and simple operational process. This study is a review of the recent literature on the use of natural and modified lignocellulosic residues for Cr adsorption. The Cr maximum adsorption capacity and the adsorption mechanism under different experimental conditions are reported when possibly."
1509816,Augustynowicz et al. 2010,Chromium(VI) bioremediation by aquatic macrophyte Callitriche cophocarpa Sendtn,"Callitriche cophocarpa (water-starwort)--aquatic widespread macrophyte--was found to be an excellent chromium accumulator. The plants were exposed to various chromium(VI) concentration ranging from 50 to 700 microM in a hydroponic culture up to ca. 3 weeks. Physiological conditions of shoots were monitored via measuring potential photosynthesis quantum efficiency (F(v)/F(m)) and photosynthetic pigment contents. Additionally, the structure of leaves was analyzed using optical and atomic force microscopy (AFM). It has been shown that plants grown in 50 microM Cr(VI) solution exhibited photosynthetic activity and shoot and leaf morphology similar to control plants. Moreover, at the same time the average Cr concentration in their shoots reached about 470 mg kg(-1)d.w. after 10d and up to 1000 mg kg(-1)d.w. after 3 weeks of culture while in control plants did not exceed a few mgkg(-1)d.w. Our results point to Callitriche cophocarpa as a very promising species to be used in the investigation of chromium(VI) phytoremediation mechanisms as well as a good candidate for wastewaters remediation purpose.","Chromium(VI) bioremediation by aquatic macrophyte Callitriche cophocarpa Sendtn Abs: Callitriche cophocarpa (water-starwort)--aquatic widespread macrophyte--was found to be an excellent chromium accumulator. The plants were exposed to various chromium(VI) concentration ranging from 50 to 700 microM in a hydroponic culture up to ca. 3 weeks. Physiological conditions of shoots were monitored via measuring potential photosynthesis quantum efficiency (F(v)/F(m)) and photosynthetic pigment contents. Additionally, the structure of leaves was analyzed using optical and atomic force microscopy (AFM). It has been shown that plants grown in 50 microM Cr(VI) solution exhibited photosynthetic activity and shoot and leaf morphology similar to control plants. Moreover, at the same time the average Cr concentration in their shoots reached about 470 mg kg(-1)d.w. after 10d and up to 1000 mg kg(-1)d.w. after 3 weeks of culture while in control plants did not exceed a few mgkg(-1)d.w. Our results point to Callitriche cophocarpa as a very promising species to be used in the investigation of chromium(VI) phytoremediation mechanisms as well as a good candidate for wastewaters remediation purpose."
1509815,Giloni-Lima et al. 2010,A study of the effects of chromium exposure on the growth of Pseudokirchneriella subcapitata (Korshikov) hindak evaluated by Central Composite Design and Response Surface Methodology,"The aim of this study was to evaluate the effects of chromium exposure on the growth of P. subcapitata using the Central Composite Design (CCD) and Response Surface Methodology (RSM). The highest values for algal density and biomass were obtained in the longest exposure times and for the lowest chromium concentrations. The CCD used for the analysis of treatment combinations showed that a second order polynomial regression model was in good agreement with experimental results, with R (2) = 81.50 and 89.90; for algal density and biomass (p &lt; 0.05), respectively. Only the exposure time was significant for algal density. For chlorophyll, in contrast, the exposure time, chromium concentration and their interaction significantly affected the growth of P. subcapitata. The findings confirmed the sensitivity of P. subcapitata to chromium (VI), which makes it a suitable bioindicator of environmental contamination for this metal.","A study of the effects of chromium exposure on the growth of Pseudokirchneriella subcapitata (Korshikov) hindak evaluated by Central Composite Design and Response Surface Methodology Abs: The aim of this study was to evaluate the effects of chromium exposure on the growth of P. subcapitata using the Central Composite Design (CCD) and Response Surface Methodology (RSM). The highest values for algal density and biomass were obtained in the longest exposure times and for the lowest chromium concentrations. The CCD used for the analysis of treatment combinations showed that a second order polynomial regression model was in good agreement with experimental results, with R (2) = 81.50 and 89.90; for algal density and biomass (p &lt; 0.05), respectively. Only the exposure time was significant for algal density. For chlorophyll, in contrast, the exposure time, chromium concentration and their interaction significantly affected the growth of P. subcapitata. The findings confirmed the sensitivity of P. subcapitata to chromium (VI), which makes it a suitable bioindicator of environmental contamination for this metal."
1509814,Buendía-González et al. 2010,Prosopis laevigata a potential chromium (VI) and cadmium (II) hyperaccumulator desert plant,"The bioaccumulation of Cr(VI) and Cd(II) in Prosopis laevigata and the effect of these heavy metals on plant growth were assessed. P. laevigata seeds were cultured during 50 days on modified Murashige-Skoog medium supplemented with four different concentrations of Cr(VI) (0-3.4mM) and Cd(II) (0-2.2mM), respectively. Heavy metals did not stop germination, but smaller plants with fewer leaves and secondary roots were produced. Seedlings showed an accumulation of 8176 and 21,437 mg Cd kg(-1) and of 5461 and 8090 mg Cr kg(-1) dry weight, in shoot and root, when cultured with 0.65 mM Cd(II) and 3.4mM Cr(VI), respectively. These results indicated that significant translocation from the roots unto aerial parts took place. A bioaccumulation factor greater than 100 for Cd and 24 for Cr was exhibited by the seedlings. P. laevigata can be considered as a potential hyperaccumulator of Cd(II) and Cr(VI) species and considered as a promising candidate for phytoremediation purposes.","Prosopis laevigata a potential chromium (VI) and cadmium (II) hyperaccumulator desert plant Abs: The bioaccumulation of Cr(VI) and Cd(II) in Prosopis laevigata and the effect of these heavy metals on plant growth were assessed. P. laevigata seeds were cultured during 50 days on modified Murashige-Skoog medium supplemented with four different concentrations of Cr(VI) (0-3.4mM) and Cd(II) (0-2.2mM), respectively. Heavy metals did not stop germination, but smaller plants with fewer leaves and secondary roots were produced. Seedlings showed an accumulation of 8176 and 21,437 mg Cd kg(-1) and of 5461 and 8090 mg Cr kg(-1) dry weight, in shoot and root, when cultured with 0.65 mM Cd(II) and 3.4mM Cr(VI), respectively. These results indicated that significant translocation from the roots unto aerial parts took place. A bioaccumulation factor greater than 100 for Cd and 24 for Cr was exhibited by the seedlings. P. laevigata can be considered as a potential hyperaccumulator of Cd(II) and Cr(VI) species and considered as a promising candidate for phytoremediation purposes."
1509813,Jorge et al. 2010,Studies on the stripping voltammetric determination and speciation of chromium at a rotating-disc bismuth film electrode,"An adsorptive stripping voltammetric protocol coupled with a rotating-disc bismuth film electrode for the determination and speciation of chromium (III) and chromium (VI) in the presence of diethylenetriaminepentaacetic acid (DTPA) is presented. The developed methodology involves a mass-transport controlled preconcentration step, during which a Cr(III)-DTPA complex is adsorbed onto a pre-plated rotating-disc bismuth film electrode held at -0.4V, followed by a reductive square wave stripping scan. At -1.07 V vs. Ag/AgCl, a peak is recorded due to the catalytic reduction of Cr(III)-DTPA to Cr(II)-DTPA. As a result of different chemical behaviours of Cr(III) and Cr(VI) in the presence of DTPA, the corresponding voltammetric signals presented different stabilities in time. A univariate optimization study was performed with several experimental parameters as variables. For Cr(VI) and total chromium, Cr(III)+Cr(VI), an accumulation time of 60s at -0.4V vs. Ag/AgCl resulted in detection limits of 0.336 and 0.414 nM and quantification limits of 1.12 and 1.40 nM, respectively. The relative standard deviation for 10 measurements of 5.0 nM chromate was 2.4%. Interference of other electroactive trace metals and surfactants was considered. A simple speciation scheme was proposed and satisfactorily applied to Cr(III) and Cr(VI) determinations in river water samples.","Studies on the stripping voltammetric determination and speciation of chromium at a rotating-disc bismuth film electrode Abs: An adsorptive stripping voltammetric protocol coupled with a rotating-disc bismuth film electrode for the determination and speciation of chromium (III) and chromium (VI) in the presence of diethylenetriaminepentaacetic acid (DTPA) is presented. The developed methodology involves a mass-transport controlled preconcentration step, during which a Cr(III)-DTPA complex is adsorbed onto a pre-plated rotating-disc bismuth film electrode held at -0.4V, followed by a reductive square wave stripping scan. At -1.07 V vs. Ag/AgCl, a peak is recorded due to the catalytic reduction of Cr(III)-DTPA to Cr(II)-DTPA. As a result of different chemical behaviours of Cr(III) and Cr(VI) in the presence of DTPA, the corresponding voltammetric signals presented different stabilities in time. A univariate optimization study was performed with several experimental parameters as variables. For Cr(VI) and total chromium, Cr(III)+Cr(VI), an accumulation time of 60s at -0.4V vs. Ag/AgCl resulted in detection limits of 0.336 and 0.414 nM and quantification limits of 1.12 and 1.40 nM, respectively. The relative standard deviation for 10 measurements of 5.0 nM chromate was 2.4%. Interference of other electroactive trace metals and surfactants was considered. A simple speciation scheme was proposed and satisfactorily applied to Cr(III) and Cr(VI) determinations in river water samples."
1509812,Chen et al. 2010,Separation and preconcentration system based on ultrasonic probe-assisted ionic liquid dispersive liquid-liquid microextraction for determination trace amount of chromium(VI) by electrothermal atomic absorption spectrometry,"A novel method of ultrasonic probe-assisted ionic liquid dispersive liquid-liquid microextraction combined with electrothermal atomic absorption spectrometry (ETAAS) was developed for the determination of chromium(VI) species in water samples. In this procedure, the hydrophobic chelate of chromium(VI) with ammonium pyrrolidinedithiocarbamate (APDC) was extracted into the fine droplets of 1-hexyl-3-methylimidazolium hexafluorophosphate ([Hmim][PF(6)]), which was dispersed into the aqueous sample solution by ultrasonication using an ultrasonic probe. Several variables such as the volume of [Hmim][PF(6)], sample pH, concentration of APDC, and extraction time were investigated in detail. Under the optimum conditions, the limit of detection of the proposed method was 0.07 ng mL(-1) for Cr(VI) and the relative standard deviation for five-replicated determination of 2.0 ng mL(-1) Cr(VI) was 9.2%. The proposed method has been also successfully applied to the determination of chromium(VI) species in lake and tap water samples.","Separation and preconcentration system based on ultrasonic probe-assisted ionic liquid dispersive liquid-liquid microextraction for determination trace amount of chromium(VI) by electrothermal atomic absorption spectrometry Abs: A novel method of ultrasonic probe-assisted ionic liquid dispersive liquid-liquid microextraction combined with electrothermal atomic absorption spectrometry (ETAAS) was developed for the determination of chromium(VI) species in water samples. In this procedure, the hydrophobic chelate of chromium(VI) with ammonium pyrrolidinedithiocarbamate (APDC) was extracted into the fine droplets of 1-hexyl-3-methylimidazolium hexafluorophosphate ([Hmim][PF(6)]), which was dispersed into the aqueous sample solution by ultrasonication using an ultrasonic probe. Several variables such as the volume of [Hmim][PF(6)], sample pH, concentration of APDC, and extraction time were investigated in detail. Under the optimum conditions, the limit of detection of the proposed method was 0.07 ng mL(-1) for Cr(VI) and the relative standard deviation for five-replicated determination of 2.0 ng mL(-1) Cr(VI) was 9.2%. The proposed method has been also successfully applied to the determination of chromium(VI) species in lake and tap water samples."
1509811,Cheng et al. 2009,Identification and characterization of the chromium (VI) responding protein from a newly isolated Ochrobactrum anthropi CTS-325,"A Gram-negative, chromium(VI) tolerant and reductive strain CTS-325, isolated from a Chinese chromate plant, was identified as Ochrobactrum anthropi based on its biochemical properties and 16S rDNA sequence analysis. It was able to tolerate up to 10 mmol/L Cr(VI) and completely reduce 1 mmol/L Cr(VI) to Cr(III) within 48 h. When the strain CTS-325 was induced with Cr(VI), a protein increased significantly in the whole cell proteins. Liquid chromatography tandem mass spectrometry (LC-MS/MS) analysis revealed that this protein was a superoxide dismutase (SOD) homology. The measured superoxide dismutase activity was 2694 U/mg after three steps of purification. The SOD catalyzes the dismutation of the superoxide anion (O2*-) into hydrogen peroxide and molecular oxygen. This protein is considered to be one of the most important anti-oxidative enzymes for O. anthropi as it allows the bacterium to survive high oxygen stress environments, such as the environment produced during the reduction process of Cr(VI).","Identification and characterization of the chromium (VI) responding protein from a newly isolated Ochrobactrum anthropi CTS-325 Abs: A Gram-negative, chromium(VI) tolerant and reductive strain CTS-325, isolated from a Chinese chromate plant, was identified as Ochrobactrum anthropi based on its biochemical properties and 16S rDNA sequence analysis. It was able to tolerate up to 10 mmol/L Cr(VI) and completely reduce 1 mmol/L Cr(VI) to Cr(III) within 48 h. When the strain CTS-325 was induced with Cr(VI), a protein increased significantly in the whole cell proteins. Liquid chromatography tandem mass spectrometry (LC-MS/MS) analysis revealed that this protein was a superoxide dismutase (SOD) homology. The measured superoxide dismutase activity was 2694 U/mg after three steps of purification. The SOD catalyzes the dismutation of the superoxide anion (O2*-) into hydrogen peroxide and molecular oxygen. This protein is considered to be one of the most important anti-oxidative enzymes for O. anthropi as it allows the bacterium to survive high oxygen stress environments, such as the environment produced during the reduction process of Cr(VI)."
1509810,Al Hasin et al. 2010,Remediation of chromium(VI) by a methane-oxidizing bacterium,"Methane-oxidizing bacteria are ubiquitous in the environment and are globally important in oxidizing the potent greenhouse gas methane. It is also well recognized that they have wide potential for bioremediation of organic and chlorinated organic pollutants, thanks to the wide substrate ranges of the methane monooxygenase enzymes that they produce. Here we have demonstrated that the well characterized model methanotroph Methylococcus capsulatus (Bath) is able to bioremediate chromium(VI) pollution over a wide range of concentrations (1.4-1000 mg L(-1) of Cr(6+)), thus extending the bioremediation potential of this major group of microorganisms to include an important heavy-metal pollutant. The chromium(VI) reduction reaction was dependent on the availability of reducing equivalents from the growth substrate methane and was partially inhibited by the metabolic poison sodium azide. X-ray spectroscopy showed that the cell-associated chromium was predominantly in the +3 oxidation state and associated with cell- or medium-derived moieties that were most likely phosphate groups. The genome sequence of Mc. capsulatus (Bath) suggests at least five candidate genes for the chromium(VI) reductase activity in this organism.","Remediation of chromium(VI) by a methane-oxidizing bacterium Abs: Methane-oxidizing bacteria are ubiquitous in the environment and are globally important in oxidizing the potent greenhouse gas methane. It is also well recognized that they have wide potential for bioremediation of organic and chlorinated organic pollutants, thanks to the wide substrate ranges of the methane monooxygenase enzymes that they produce. Here we have demonstrated that the well characterized model methanotroph Methylococcus capsulatus (Bath) is able to bioremediate chromium(VI) pollution over a wide range of concentrations (1.4-1000 mg L(-1) of Cr(6+)), thus extending the bioremediation potential of this major group of microorganisms to include an important heavy-metal pollutant. The chromium(VI) reduction reaction was dependent on the availability of reducing equivalents from the growth substrate methane and was partially inhibited by the metabolic poison sodium azide. X-ray spectroscopy showed that the cell-associated chromium was predominantly in the +3 oxidation state and associated with cell- or medium-derived moieties that were most likely phosphate groups. The genome sequence of Mc. capsulatus (Bath) suggests at least five candidate genes for the chromium(VI) reductase activity in this organism."
1509809,Anbia et al. 2010,Fast and efficient mesoporous adsorbents for the separation of toxic compounds from aqueous media,"The effect of cationic template on the adsorption of chromium (VI), furfural and copperphthalocyanine-3,4',4'',4'''-tetrasulfonic acid tetrasodium salt (CuPc) in MCM-41 and MCM-48 mesoporous materials was investigated in this work. We used cetyltrimethylammonium bromide (CTAB) as the cationic template and sodiummetasilicate (for MCM-41) and tetraethyl-orthosilicon (for MCM-48) as the silica source for the synthesis of mesoporous materials. The properties of synthesized samples were characterized with XRD-low angle, SEM, N(2) adsorption-desorption and TG-DT analysis. The extent of adsorption was investigated as a function of solution pH, shaking speed, contact time, analyte concentration, reaction temperature and supporting electrolyte (sodium chloride) concentration. Langmuir and Freundlich isotherms were used to model the adsorption equilibrium data. The as-synthesized mesoporous samples showed very high adsorption capacity for the analytes and adsorption uptakes were rapid on the adsorbents reaching equilibrium in less than 2 h. The materials without surfactant did not show significant affinity for the analytes.","Fast and efficient mesoporous adsorbents for the separation of toxic compounds from aqueous media Abs: The effect of cationic template on the adsorption of chromium (VI), furfural and copperphthalocyanine-3,4',4'',4'''-tetrasulfonic acid tetrasodium salt (CuPc) in MCM-41 and MCM-48 mesoporous materials was investigated in this work. We used cetyltrimethylammonium bromide (CTAB) as the cationic template and sodiummetasilicate (for MCM-41) and tetraethyl-orthosilicon (for MCM-48) as the silica source for the synthesis of mesoporous materials. The properties of synthesized samples were characterized with XRD-low angle, SEM, N(2) adsorption-desorption and TG-DT analysis. The extent of adsorption was investigated as a function of solution pH, shaking speed, contact time, analyte concentration, reaction temperature and supporting electrolyte (sodium chloride) concentration. Langmuir and Freundlich isotherms were used to model the adsorption equilibrium data. The as-synthesized mesoporous samples showed very high adsorption capacity for the analytes and adsorption uptakes were rapid on the adsorbents reaching equilibrium in less than 2 h. The materials without surfactant did not show significant affinity for the analytes."
1509808,Idris et al. 2010,Photocatalytic magnetic separable beads for chromium (VI) reduction,"Magnetically separable photocatalyst beads containing nano-sized iron oxide in alginate polymer were prepared. This magnetic photocatalyst beads are used in slurry-type reactors. The magnetism of the catalyst arises from the nanostructured particles gamma-Fe(2)O(3), by which the catalyst can be easily recovered by the application of an external magnetic field. These synthesized beads are sunlight-driven photocatalyst. In the system without magnetic photocatalyst beads, no chromium reduction was observed under sunlight irradiation due to the stability of the chromium (VI). Upon the addition of magnetic photocatalyst beads, the photo-reduction of Cr(VI) was completed in just after only 50min under sunlight irradiation due to the photocatalytic activity of the beads. However when placed away from sunlight, the reduction rate of the chromium is just about 10%. These observations were explained in terms of absorption occurrence of chromium (VI) onto the catalyst surface which took place in this reaction. In addition, photo-reduction rate of chromium (VI) was more significant at lower pH. The results suggest that the use of magnetic separable photocatalyst beads is a feasible strategy for eliminating Cr(VI).","Photocatalytic magnetic separable beads for chromium (VI) reduction Abs: Magnetically separable photocatalyst beads containing nano-sized iron oxide in alginate polymer were prepared. This magnetic photocatalyst beads are used in slurry-type reactors. The magnetism of the catalyst arises from the nanostructured particles gamma-Fe(2)O(3), by which the catalyst can be easily recovered by the application of an external magnetic field. These synthesized beads are sunlight-driven photocatalyst. In the system without magnetic photocatalyst beads, no chromium reduction was observed under sunlight irradiation due to the stability of the chromium (VI). Upon the addition of magnetic photocatalyst beads, the photo-reduction of Cr(VI) was completed in just after only 50min under sunlight irradiation due to the photocatalytic activity of the beads. However when placed away from sunlight, the reduction rate of the chromium is just about 10%. These observations were explained in terms of absorption occurrence of chromium (VI) onto the catalyst surface which took place in this reaction. In addition, photo-reduction rate of chromium (VI) was more significant at lower pH. The results suggest that the use of magnetic separable photocatalyst beads is a feasible strategy for eliminating Cr(VI)."
1509807,Kiliç et al. 2010,Proteomic changes in response to chromium(VI) toxicity in Pseudomonas aeruginosa,"A proteomic approach was used to identify proteins involved in Cr(VI) stress response of Pseudomonas aeruginosa to toxic Cr(VI). Cytosolic and membrane fractions from bacteria exposed to 300 mg l(-1) Cr(VI) were prepared, 2D gel electrophoresis in combination with MALDI-TOF MS and LC-MS/MS was used to identify proteins whose expression level increased or decreased upon exposure to Cr(VI). Overexpressed proteins include stress proteins, proteins involved in protein biosynthesis, proteins responsible for energy production, proteins involved in free radicals detoxification by the glutathione system, outer membrane proteins, MucD, while downregulated proteins were isocitrate dehydrogenase and 30S ribosomal protein S1. Under Cr(VI) exposure, upregulation of MucD (role in exopolysaccharide production) and outer membrane proteins concluded that bacteria have access to more than one resistance mechanism against toxic metal ions. We propose that the mechanisms of Cr(VI) resistance include production of exopolysaccharide and complexing of metal ions outside the cell.","Proteomic changes in response to chromium(VI) toxicity in Pseudomonas aeruginosa Abs: A proteomic approach was used to identify proteins involved in Cr(VI) stress response of Pseudomonas aeruginosa to toxic Cr(VI). Cytosolic and membrane fractions from bacteria exposed to 300 mg l(-1) Cr(VI) were prepared, 2D gel electrophoresis in combination with MALDI-TOF MS and LC-MS/MS was used to identify proteins whose expression level increased or decreased upon exposure to Cr(VI). Overexpressed proteins include stress proteins, proteins involved in protein biosynthesis, proteins responsible for energy production, proteins involved in free radicals detoxification by the glutathione system, outer membrane proteins, MucD, while downregulated proteins were isocitrate dehydrogenase and 30S ribosomal protein S1. Under Cr(VI) exposure, upregulation of MucD (role in exopolysaccharide production) and outer membrane proteins concluded that bacteria have access to more than one resistance mechanism against toxic metal ions. We propose that the mechanisms of Cr(VI) resistance include production of exopolysaccharide and complexing of metal ions outside the cell."
1509806,Tandukar et al. 2009,Biological chromium(VI) reduction in the cathode of a microbial fuel cell,"The biocathode of a microbial fuel cell (MFC) offers a promising potential for the reductive treatment of oxidized pollutants. In this study, we demonstrated biological Cr(VI) reduction in the cathode of a MFC and identified putative Cr(VI) reducing microorganisms. The MFC was continuously monitored for Cr(VI) reduction and power generation. Acetate was provided to the anode compartment as substrate and bicarbonate was added to the cathode compartment as the sole external carbon source. The contribution of biomass decay and abiotic processes on Cr(VI) reduction was minimal, confirming that most of the Cr(VI) reduction was assisted by microbial activity in the cathode, which utilizes electrons and protons generated from the oxidation of acetate in the anode compartment. Relatively fast Cr(VI) reduction was observed at initial Cr(VI) concentrations below 80 mg/L. However, at 80 mg Cr(VI)/L, Cr(VI) reduction was extremely slow. A maximum Cr(VI) reduction rate of 0.46 mg Cr(VI)/g VSS.h was achieved, which resulted in a current and power density of 123.4 mA/m(2) and 55.5 mW/m(2), respectively. The reduced chromium was nondetectable in the supernatant of the catholyte which indicated complete removal of chromium as Cr(OH)(3) precipitate. Analysis of the 16S rRNA gene based clone library revealed that the cathode biomass was largely dominated by phylotypes closely related to Trichococcus pasteurii and Pseudomonas aeruginosa, the putative Cr(VI) reducers.","Biological chromium(VI) reduction in the cathode of a microbial fuel cell Abs: The biocathode of a microbial fuel cell (MFC) offers a promising potential for the reductive treatment of oxidized pollutants. In this study, we demonstrated biological Cr(VI) reduction in the cathode of a MFC and identified putative Cr(VI) reducing microorganisms. The MFC was continuously monitored for Cr(VI) reduction and power generation. Acetate was provided to the anode compartment as substrate and bicarbonate was added to the cathode compartment as the sole external carbon source. The contribution of biomass decay and abiotic processes on Cr(VI) reduction was minimal, confirming that most of the Cr(VI) reduction was assisted by microbial activity in the cathode, which utilizes electrons and protons generated from the oxidation of acetate in the anode compartment. Relatively fast Cr(VI) reduction was observed at initial Cr(VI) concentrations below 80 mg/L. However, at 80 mg Cr(VI)/L, Cr(VI) reduction was extremely slow. A maximum Cr(VI) reduction rate of 0.46 mg Cr(VI)/g VSS.h was achieved, which resulted in a current and power density of 123.4 mA/m(2) and 55.5 mW/m(2), respectively. The reduced chromium was nondetectable in the supernatant of the catholyte which indicated complete removal of chromium as Cr(OH)(3) precipitate. Analysis of the 16S rRNA gene based clone library revealed that the cathode biomass was largely dominated by phylotypes closely related to Trichococcus pasteurii and Pseudomonas aeruginosa, the putative Cr(VI) reducers."
1509805,Durante et al. 2010,Exhaustive depletion of recalcitrant chromium fractions in a real wastewater,"This paper reports investigations on electrochemical removal of Cr(III) from a real wastewater sample from a 4x10(4)m(3)d(-1) purification plant located in the leather district of Arzignano (Italy). A crucial point evaluated is the relation between Cr(III) abatement and the reduction of total organic carbon and chemical oxygen demand. Here we present the results of different abatement approaches including advanced oxidation processes (AOPs) and electrocoagulation applied separately or in series. Neither of these methods show satisfactory results when applied alone. In particular, AOPs are completely inefficient owing to the formation of Cr(VI), which is more soluble than Cr(III). Almost total depletion (99.7%) of the recalcitrant fraction of Cr(III) is successfully achieved by combining ozonization and electrocoagulation processes. The results are consistent with the abatement of Cr in its hexavalent form by fast precipitation as NH(4)Fe(CrO(4))(2).","Exhaustive depletion of recalcitrant chromium fractions in a real wastewater Abs: This paper reports investigations on electrochemical removal of Cr(III) from a real wastewater sample from a 4x10(4)m(3)d(-1) purification plant located in the leather district of Arzignano (Italy). A crucial point evaluated is the relation between Cr(III) abatement and the reduction of total organic carbon and chemical oxygen demand. Here we present the results of different abatement approaches including advanced oxidation processes (AOPs) and electrocoagulation applied separately or in series. Neither of these methods show satisfactory results when applied alone. In particular, AOPs are completely inefficient owing to the formation of Cr(VI), which is more soluble than Cr(III). Almost total depletion (99.7%) of the recalcitrant fraction of Cr(III) is successfully achieved by combining ozonization and electrocoagulation processes. The results are consistent with the abatement of Cr in its hexavalent form by fast precipitation as NH(4)Fe(CrO(4))(2)."
1509804,Gupta et al. 2010,Adsorption studies on the removal of hexavalent chromium from aqueous solution using a low cost fertilizer industry waste material,"Low cost fertilizer industry waste material called carbon slurry, produced in generators of fuel oil-based industrial generators, was converted into an effective and efficient adsorbent for the removal of hexavalent chromium(VI) from aqueous solutions. The waste was chemically treated, activated, characterized, and used for the adsorption of chromium. The work involves batch experiments to investigate the effect of contact time, pH, temperature, concentration, and adsorbent dose on the extent of adsorption by carbon slurry. The maximum adsorption was found at 70min, 2.0 pH, 4.0g/L dose, and 303K temperature. Maximum adsorption capacity (15.24mg/g) of Cr(VI) on carbon slurry was observed at 100mg/L initial Cr(VI) concentration. Langmuir and Freundlich adsorption isotherm models were applied to analyze adsorption data, and both were found to be applicable to this adsorption system, in terms of relatively high regression values. Thermodynamic parameters showed that the adsorption of Cr(VI) onto carbon slurry was feasible, spontaneous, and exothermic under the studied conditions. Kinetics of adsorption was found to follow the pseudo-second-order rate equation. Column studies have been carried out to compare these with the batch capacities. The recovery of Cr(VI) and chemical regeneration of the spent column have also been tried. In all, the results indicated that the adsorbent used in this work proved to be effective material for the treatment of chromium-bearing aqueous solutions.","Adsorption studies on the removal of hexavalent chromium from aqueous solution using a low cost fertilizer industry waste material Abs: Low cost fertilizer industry waste material called carbon slurry, produced in generators of fuel oil-based industrial generators, was converted into an effective and efficient adsorbent for the removal of hexavalent chromium(VI) from aqueous solutions. The waste was chemically treated, activated, characterized, and used for the adsorption of chromium. The work involves batch experiments to investigate the effect of contact time, pH, temperature, concentration, and adsorbent dose on the extent of adsorption by carbon slurry. The maximum adsorption was found at 70min, 2.0 pH, 4.0g/L dose, and 303K temperature. Maximum adsorption capacity (15.24mg/g) of Cr(VI) on carbon slurry was observed at 100mg/L initial Cr(VI) concentration. Langmuir and Freundlich adsorption isotherm models were applied to analyze adsorption data, and both were found to be applicable to this adsorption system, in terms of relatively high regression values. Thermodynamic parameters showed that the adsorption of Cr(VI) onto carbon slurry was feasible, spontaneous, and exothermic under the studied conditions. Kinetics of adsorption was found to follow the pseudo-second-order rate equation. Column studies have been carried out to compare these with the batch capacities. The recovery of Cr(VI) and chemical regeneration of the spent column have also been tried. In all, the results indicated that the adsorbent used in this work proved to be effective material for the treatment of chromium-bearing aqueous solutions."
1509803,Garavaglia et al. 2010,Chromium (VI) biotransformation by beta- and gamma-Proteobacteria from natural polluted environments: a combined biological and chemical treatment for industrial wastes,"The high solubility of Cr(VI) in aqueous systems, together with carcinogenic and mutagenic effects on living organisms, make industrial effluents receive specific treatments for Cr(VI) elimination. Biotreatments, based on biotransformation of Cr(VI) to Cr(III) which is immobilized as Cr(OH)(3), are the most effective methods for the removal of Cr(VI) concentrations below 2mM. The aim of our study is the application of pure or mixed bacterial cultures for Cr(VI) biotransformation followed by chemical flocculation of Cr(OH)(3) as a combined treatment for industrial wastes. Pseudomonas veronii 2E, Delftia acidovorans AR, Klebsiella oxytoca P2 and Klebsiella ornithinolytica 1P, isolated from polluted environments showed a decrease from 38.83 to 74.32%, in 0.05 mM of initial Cr(VI). As revealed DGGE experiments, P. veronii 2E and K. ornithinolytica 1P could develop together in cocultures and in these conditions a 72.88% of Cr(VI) present was removed. Although the pH of the cultures was 8, no Cr(OH)(3) sediment was detected. The results of total chromium quantification support this observation. The precipitation of Cr(III) was induced using different commercial flocculants. Best yields were obtained using Na(2)CO(3) 0.1M, which allowed the flocculation of almost 100% of Cr(III) present. This combined treatment would be an economical and ecological way to remove Cr(VI).","Chromium (VI) biotransformation by beta- and gamma-Proteobacteria from natural polluted environments: a combined biological and chemical treatment for industrial wastes Abs: The high solubility of Cr(VI) in aqueous systems, together with carcinogenic and mutagenic effects on living organisms, make industrial effluents receive specific treatments for Cr(VI) elimination. Biotreatments, based on biotransformation of Cr(VI) to Cr(III) which is immobilized as Cr(OH)(3), are the most effective methods for the removal of Cr(VI) concentrations below 2mM. The aim of our study is the application of pure or mixed bacterial cultures for Cr(VI) biotransformation followed by chemical flocculation of Cr(OH)(3) as a combined treatment for industrial wastes. Pseudomonas veronii 2E, Delftia acidovorans AR, Klebsiella oxytoca P2 and Klebsiella ornithinolytica 1P, isolated from polluted environments showed a decrease from 38.83 to 74.32%, in 0.05 mM of initial Cr(VI). As revealed DGGE experiments, P. veronii 2E and K. ornithinolytica 1P could develop together in cocultures and in these conditions a 72.88% of Cr(VI) present was removed. Although the pH of the cultures was 8, no Cr(OH)(3) sediment was detected. The results of total chromium quantification support this observation. The precipitation of Cr(III) was induced using different commercial flocculants. Best yields were obtained using Na(2)CO(3) 0.1M, which allowed the flocculation of almost 100% of Cr(III) present. This combined treatment would be an economical and ecological way to remove Cr(VI)."
1509802,Kiser and  Manning 2010,Reduction and immobilization of chromium(VI) by iron(II)-treated faujasite,"Removal of hexavalent chromium (Cr(VI)) from wastewater typically involves reduction of Cr(VI) to insoluble Cr(III) using zerovalent iron (Fe(0)) or ferrous iron (Fe(II)). This study investigates the effectiveness of Fe(II)-treated faujasite (zeolite Fe(II)-Y) for reduction of Cr(VI) and immobilization (adsorption/co-precipitation) of the Cr(III) reaction product. The Fe(II)-faujasite material effectively removed high concentrations of dissolved Cr(VI) from aqueous solution resulting in Cr solid loadings as high as 0.30 mmol Cr per gram Fe(II)-faujasite or approximately 1.5% Cr (w:w). Results of Cr K-edge X-ray absorption near edge spectroscopy (XANES) confirmed that the oxidation state of Cr in Cr(VI)-treated Fe(II)-faujasite was Cr(III). The local atomic structure of Cr was investigated by extended X-ray absorption fine structure (EXAFS) spectroscopy and the structure of Cr in the product was described by a Cr-O first shell of six O atoms at 1.98(+/-0.02)A plus a second atomic shell of metal (Cr, Fe) at 3.13(+/-0.02)A. The EXAFS results, combined with SEM imaging and X-ray diffraction analyses, suggested that the product of the reaction of Cr(VI) with Fe(II)-faujasite is primarily a poorly order Cr(x)Fe(1-x)(OH)(3) mixed phase similar to previous investigations of the reaction of Cr(VI) with Fe(0) and not solely Cr(III) bound directly to zeolite cation exchange sites.","Reduction and immobilization of chromium(VI) by iron(II)-treated faujasite Abs: Removal of hexavalent chromium (Cr(VI)) from wastewater typically involves reduction of Cr(VI) to insoluble Cr(III) using zerovalent iron (Fe(0)) or ferrous iron (Fe(II)). This study investigates the effectiveness of Fe(II)-treated faujasite (zeolite Fe(II)-Y) for reduction of Cr(VI) and immobilization (adsorption/co-precipitation) of the Cr(III) reaction product. The Fe(II)-faujasite material effectively removed high concentrations of dissolved Cr(VI) from aqueous solution resulting in Cr solid loadings as high as 0.30 mmol Cr per gram Fe(II)-faujasite or approximately 1.5% Cr (w:w). Results of Cr K-edge X-ray absorption near edge spectroscopy (XANES) confirmed that the oxidation state of Cr in Cr(VI)-treated Fe(II)-faujasite was Cr(III). The local atomic structure of Cr was investigated by extended X-ray absorption fine structure (EXAFS) spectroscopy and the structure of Cr in the product was described by a Cr-O first shell of six O atoms at 1.98(+/-0.02)A plus a second atomic shell of metal (Cr, Fe) at 3.13(+/-0.02)A. The EXAFS results, combined with SEM imaging and X-ray diffraction analyses, suggested that the product of the reaction of Cr(VI) with Fe(II)-faujasite is primarily a poorly order Cr(x)Fe(1-x)(OH)(3) mixed phase similar to previous investigations of the reaction of Cr(VI) with Fe(0) and not solely Cr(III) bound directly to zeolite cation exchange sites."
1509801,Karatepe et al. 2010,Development of a coprecipitation system for the speciation/preconcentration of chromium in tap waters,"A method for the speciation of chromium(III), chromium(VI) and determination of total chromium based on coprecipitation of chromium(III) with dysprosium hydroxide has been investigated and applied to tap water samples. Chromium(III) was quantitatively recovered by the presented method, while the recovery values for chromium(VI) was below 10%. The influences of analytical parameters including amount of dysprosium(III), pH, centrifugation speed and sample volume for the quantitative precipitation were examined. No interferic effects were observed from alkali, earth alkali and some transition metals for the analyte ions. The detection limits (k=3, N=15) were 0.65 microg/L for chromium(III) and 0.78 microg/L for chromium(VI). The validation of the presented method was checked by the analysis of certified reference materials.","Development of a coprecipitation system for the speciation/preconcentration of chromium in tap waters Abs: A method for the speciation of chromium(III), chromium(VI) and determination of total chromium based on coprecipitation of chromium(III) with dysprosium hydroxide has been investigated and applied to tap water samples. Chromium(III) was quantitatively recovered by the presented method, while the recovery values for chromium(VI) was below 10%. The influences of analytical parameters including amount of dysprosium(III), pH, centrifugation speed and sample volume for the quantitative precipitation were examined. No interferic effects were observed from alkali, earth alkali and some transition metals for the analyte ions. The detection limits (k=3, N=15) were 0.65 microg/L for chromium(III) and 0.78 microg/L for chromium(VI). The validation of the presented method was checked by the analysis of certified reference materials."
1509800,Kong et al. 2009,Kinetic study and mathematical modeling of chromium(VI) reduction and microorganism growth under mixed culture,"The kinetics of chromium(VI) reduction by Pseudomonas aeruginosa (P. aeruginosa) and Escherichia coli (E. coli) was studied under both pure and mixed cultures. Initially, the study of kinetics was performed in pure culture. It was observed that the growth of the two bacteria was both inhibited in the presence of chromium(VI). The maximum specific growth rate (mu( m )) of P. aeruginosa decreased from 2.3942 h(-1) (without Cr(VI)) to 1.8551 h(-1) (with Cr(VI)). Under the mixed culture, the growth of E. coli was inhibited by P. aeruginosa. The maximum specific growth rate (mu( m )) of E. coli decreased form 0.871 h(-1) (in pure culture) to 0.153 h(-1) (in mixed culture). When the concentration of each bacterium was 4.5 x 10(8) cells ml(-1), the half-velocity reduction rate constant (K (C)) and the maximum specific reduction rate constant (v (max)) of chromium(VI) were 80.05 mg chromium(VI) l(-1) and 3.674 mg chromium(VI) cells(-1) h(-1), respectively. The results showed that the simulation appeared in good agreement with the experimental data, supporting the series of mathematical models represented the bacteria growth and chromium(VI) reduction in both pure and mixed cultures usefully.","Kinetic study and mathematical modeling of chromium(VI) reduction and microorganism growth under mixed culture Abs: The kinetics of chromium(VI) reduction by Pseudomonas aeruginosa (P. aeruginosa) and Escherichia coli (E. coli) was studied under both pure and mixed cultures. Initially, the study of kinetics was performed in pure culture. It was observed that the growth of the two bacteria was both inhibited in the presence of chromium(VI). The maximum specific growth rate (mu( m )) of P. aeruginosa decreased from 2.3942 h(-1) (without Cr(VI)) to 1.8551 h(-1) (with Cr(VI)). Under the mixed culture, the growth of E. coli was inhibited by P. aeruginosa. The maximum specific growth rate (mu( m )) of E. coli decreased form 0.871 h(-1) (in pure culture) to 0.153 h(-1) (in mixed culture). When the concentration of each bacterium was 4.5 x 10(8) cells ml(-1), the half-velocity reduction rate constant (K (C)) and the maximum specific reduction rate constant (v (max)) of chromium(VI) were 80.05 mg chromium(VI) l(-1) and 3.674 mg chromium(VI) cells(-1) h(-1), respectively. The results showed that the simulation appeared in good agreement with the experimental data, supporting the series of mathematical models represented the bacteria growth and chromium(VI) reduction in both pure and mixed cultures usefully."
1509799,Uluozlu et al. 2009,"3-Ethyl-4-(p-chlorobenzylidenamino-4,5-dihydro-1H-1,2,4-triazol-5-one (EPHBAT) as precipitant for carrier element free coprecipitation and speciation of chromium(III) and chromium(VI)","A method for the separation and speciative determination of Cr(VI) and Cr(III) has been developed. The procedure is based on coprecipitation of Cr(III) on 3-ethyl-4-(p-chlorobenzylidenamino-4,5-dihydro-1H-1,2,4-triazol-5-one (EPHBAT) without carrier element. The Cr(III) can be selectively precipitated on EPHBAT in the pH range of 8.0-9.0, while Cr(VI) cannot be retained. Total chromium was determined after the reduction of Cr(VI) to Cr(III) with 0.5 mL of concentrated H2SO4 and 0.5 mL of ethanol. Cr(VI) concentrations were obtained as the respective differences between total chromium and Cr(III). Experiments were performed to optimize conditions, such as pH, amounts of EPHBAT, sample volume, etc. A preconcentration factor of 50-fold was achieved for Cr(III). The detection limit of the method for Cr(III) was 1.0 microg L(-1). To validate the developed method, the certified reference materials (NIST SRM 1573a and GBW 0703) were analyzed. The method was applied for the speciation of chromium in spiked natural water samples with satisfactory results.","3-Ethyl-4-(p-chlorobenzylidenamino-4,5-dihydro-1H-1,2,4-triazol-5-one (EPHBAT) as precipitant for carrier element free coprecipitation and speciation of chromium(III) and chromium(VI) Abs: A method for the separation and speciative determination of Cr(VI) and Cr(III) has been developed. The procedure is based on coprecipitation of Cr(III) on 3-ethyl-4-(p-chlorobenzylidenamino-4,5-dihydro-1H-1,2,4-triazol-5-one (EPHBAT) without carrier element. The Cr(III) can be selectively precipitated on EPHBAT in the pH range of 8.0-9.0, while Cr(VI) cannot be retained. Total chromium was determined after the reduction of Cr(VI) to Cr(III) with 0.5 mL of concentrated H2SO4 and 0.5 mL of ethanol. Cr(VI) concentrations were obtained as the respective differences between total chromium and Cr(III). Experiments were performed to optimize conditions, such as pH, amounts of EPHBAT, sample volume, etc. A preconcentration factor of 50-fold was achieved for Cr(III). The detection limit of the method for Cr(III) was 1.0 microg L(-1). To validate the developed method, the certified reference materials (NIST SRM 1573a and GBW 0703) were analyzed. The method was applied for the speciation of chromium in spiked natural water samples with satisfactory results."
1509798,Li et al. 2009,Different survival of chromium-exposed Oxya chinensis among allozyme genotypes,"The goal of the present study was to compare the different survival of Oxya chinensis exposed to chromium(VI) among allozyme genotypes to gain a better understanding of the relationship between the genetic variations and environmental disturbance. This study analyzed the occurrence of genotypes in O. chinensis population exposed to Cr(VI). O. chinensis samples were collected at Yuanping, Shanxi Province, China and used in acute toxicity tests. Specimens were assigned to Cr(VI) exposure (LD50: 291.0 mg/kg) for 24 h. The genetic composition of both dead and survived specimens was analyzed with horizontal starch gel electrophoresis in four enzymes (GPI, PGM, LDH, and ME). The results indicated that under Cr(VI) exposure, specimens with different genotypes had various mortalities at the four loci in laboratory conditions, and there was a genetic basis for tolerance in O. chinensis during acute exposure to Cr(VI).","Different survival of chromium-exposed Oxya chinensis among allozyme genotypes Abs: The goal of the present study was to compare the different survival of Oxya chinensis exposed to chromium(VI) among allozyme genotypes to gain a better understanding of the relationship between the genetic variations and environmental disturbance. This study analyzed the occurrence of genotypes in O. chinensis population exposed to Cr(VI). O. chinensis samples were collected at Yuanping, Shanxi Province, China and used in acute toxicity tests. Specimens were assigned to Cr(VI) exposure (LD50: 291.0 mg/kg) for 24 h. The genetic composition of both dead and survived specimens was analyzed with horizontal starch gel electrophoresis in four enzymes (GPI, PGM, LDH, and ME). The results indicated that under Cr(VI) exposure, specimens with different genotypes had various mortalities at the four loci in laboratory conditions, and there was a genetic basis for tolerance in O. chinensis during acute exposure to Cr(VI)."
1509797,Molokwane and  Nkhalambayausi-Chirwa 2009,Microbial culture dynamics and chromium (VI) removal in packed-column microcosm reactors,"Microbial Cr(VI) reduction in groundwater aquifer media was investigated in microcosm reactors extracted from Cr(VI) contaminated sites in South Africa. The reactors were operated under an influent Cr(VI) concentration of 40 mg/L to simulate the current Cr(VI) level at the contaminated site. Near complete Cr(VI) removal was observed in microcosm reactors inoculated with Cr(VI) reducing bacteria from dried activated sludge collected from a treatment plant receiving periodic loadings of Cr(VI). The best performance was observed under low hydraulic loading (flow rate, Q=0.310 cm(3)/hr). Microbial culture characterisation results showed a change in culture composition after 17 days of reactor operation, indicating Bacillus and Lysinibacillus species as the most dominant organisms in reactors that reduced Cr(VI). The predominance of Bacillus and Lysinibacillus species was either due to resilience against toxicity or adaptation to the changing conditions in the reactor. This research was the initial step towards the development of an in situ bioremediation process to contain the spread of a Cr(VI) plume in a groundwater aquifer at contaminated site in Brits, South Africa. South Africa holds about 72% percent of the world's chromium resources, the majority of which is mined in the North Eastern region of the country formally known as Transvaal.","Microbial culture dynamics and chromium (VI) removal in packed-column microcosm reactors Abs: Microbial Cr(VI) reduction in groundwater aquifer media was investigated in microcosm reactors extracted from Cr(VI) contaminated sites in South Africa. The reactors were operated under an influent Cr(VI) concentration of 40 mg/L to simulate the current Cr(VI) level at the contaminated site. Near complete Cr(VI) removal was observed in microcosm reactors inoculated with Cr(VI) reducing bacteria from dried activated sludge collected from a treatment plant receiving periodic loadings of Cr(VI). The best performance was observed under low hydraulic loading (flow rate, Q=0.310 cm(3)/hr). Microbial culture characterisation results showed a change in culture composition after 17 days of reactor operation, indicating Bacillus and Lysinibacillus species as the most dominant organisms in reactors that reduced Cr(VI). The predominance of Bacillus and Lysinibacillus species was either due to resilience against toxicity or adaptation to the changing conditions in the reactor. This research was the initial step towards the development of an in situ bioremediation process to contain the spread of a Cr(VI) plume in a groundwater aquifer at contaminated site in Brits, South Africa. South Africa holds about 72% percent of the world's chromium resources, the majority of which is mined in the North Eastern region of the country formally known as Transvaal."
1509796,Pandey et al. 2009,Chromium effect on ROS generation and detoxification in pea (Pisum sativum) leaf chloroplasts,"Pea plants were exposed to 0, 20, 50, and 100 microM chromium [Cr(VI)] to investigate oxidative stress in isolated chloroplasts. Leaf area and biomass accumulation were significantly reduced at higher Cr supply. Generation of superoxide, hydrogen peroxide, and *OH radical generation was enhanced in the chloroplasts isolated from Cr-exposed pea plants. Cr(VI) significantly reduced F(v)/F(m) ratio of chlorophyll (Chl) fluorescence, Chl content, and whole chain electron transport rate. Superoxide dismutase (SOD) activity increased at lower Cr supply while it decreased at higher Cr supply. Ascorbate peroxidase (APX) was found to be most sensitive to Cr stress. Monodehydroascorbate reductase activity remained higher at 20 and 50 microM Cr but decreased at 100 microM Cr. Increased activities of dehydroascorbate reductase (DHAR) and glutathione reductase (GR) in the isolated chloroplasts were observed during the initial 3 days of Cr exposure of pea plants. Activities of DHAR and GR were increased up to day 3 only. Ascorbate and glutathione (GSH) pools showed similar decrease that was more evident in the GSH pool as the duration of Cr treatment increased. Observed changes in reactive oxygen species concentration, photosynthetic characteristics, and antioxidant system indicate that chloroplasts in Cr-exposed pea plants are an important target of oxidative stress.","Chromium effect on ROS generation and detoxification in pea (Pisum sativum) leaf chloroplasts Abs: Pea plants were exposed to 0, 20, 50, and 100 microM chromium [Cr(VI)] to investigate oxidative stress in isolated chloroplasts. Leaf area and biomass accumulation were significantly reduced at higher Cr supply. Generation of superoxide, hydrogen peroxide, and *OH radical generation was enhanced in the chloroplasts isolated from Cr-exposed pea plants. Cr(VI) significantly reduced F(v)/F(m) ratio of chlorophyll (Chl) fluorescence, Chl content, and whole chain electron transport rate. Superoxide dismutase (SOD) activity increased at lower Cr supply while it decreased at higher Cr supply. Ascorbate peroxidase (APX) was found to be most sensitive to Cr stress. Monodehydroascorbate reductase activity remained higher at 20 and 50 microM Cr but decreased at 100 microM Cr. Increased activities of dehydroascorbate reductase (DHAR) and glutathione reductase (GR) in the isolated chloroplasts were observed during the initial 3 days of Cr exposure of pea plants. Activities of DHAR and GR were increased up to day 3 only. Ascorbate and glutathione (GSH) pools showed similar decrease that was more evident in the GSH pool as the duration of Cr treatment increased. Observed changes in reactive oxygen species concentration, photosynthetic characteristics, and antioxidant system indicate that chloroplasts in Cr-exposed pea plants are an important target of oxidative stress."
1509795,Nityanandi and  Subbhuraam 2009,Kinetics and thermodynamic of adsorption of chromium(VI) from aqueous solution using puresorbe,"This paper deals with an investigation on coir-based adsorbent, puresorbe, in the removal of chromium(VI) from the aqueous solutions. The adsorption of chromium(VI) was carried out by varying the parameters such as agitation time, metal concentration, adsorbent dose, temperature and pH. The experimental isotherm data were analyzed using Langmuir, Freundlich and Redlich and Peterson isotherms. Adsorption followed second order rate expression for the particle size 250-500 microm at pH 2. The monolayer adsorption capacity is 76.92 mg chromium(VI) per gram of puresorbe. Thermodynamic parameters show the endothermic nature of chromium(VI) adsorption. Desorption study carried out using distilled water adjusted to pH of 2-10, suggests that chemisorption might be the mode of adsorption.","Kinetics and thermodynamic of adsorption of chromium(VI) from aqueous solution using puresorbe Abs: This paper deals with an investigation on coir-based adsorbent, puresorbe, in the removal of chromium(VI) from the aqueous solutions. The adsorption of chromium(VI) was carried out by varying the parameters such as agitation time, metal concentration, adsorbent dose, temperature and pH. The experimental isotherm data were analyzed using Langmuir, Freundlich and Redlich and Peterson isotherms. Adsorption followed second order rate expression for the particle size 250-500 microm at pH 2. The monolayer adsorption capacity is 76.92 mg chromium(VI) per gram of puresorbe. Thermodynamic parameters show the endothermic nature of chromium(VI) adsorption. Desorption study carried out using distilled water adjusted to pH of 2-10, suggests that chemisorption might be the mode of adsorption."
1509794,Kalidhasan and  Rajesh 2009,Simple and selective extraction process for chromium (VI) in industrial wastewater,"A simple and relatively green method has been developed for the determination of chromium based on the extraction of chromium (VI) as its ion-association complex with tetrabutylammoniumiodide (TBAI) in acidic medium. The ion-pair is extracted using isobutylmethylketone (MIBK) as the solvent. The concentration of the extracted chromium (VI) in the organic layer was measured spectrophotometrically at a wavelength maximum of 366 nm and the organic layer was characterized using FT-IR spectroscopy. The influence of various analytical parameters such as pH, aqueous phase volume, equilibration time, interfering ions etc. has been studied in detail. The extracted chromium (VI) was back extracted into the aqueous phase to the non-toxic chromium (III) using ascorbic acid. The calibration graph was linear in the range of 0-2 microg mL(-1) chromium (VI) with a relative standard deviation of 2.4%. A detection limit of 0.25 microg in 25 mL aqueous phase volume could be achieved and the validity of the proposed method has been checked by applying it to synthetic mixtures, spiked water sample, electroplating wastewater and certified reference material BCR-715.","Simple and selective extraction process for chromium (VI) in industrial wastewater Abs: A simple and relatively green method has been developed for the determination of chromium based on the extraction of chromium (VI) as its ion-association complex with tetrabutylammoniumiodide (TBAI) in acidic medium. The ion-pair is extracted using isobutylmethylketone (MIBK) as the solvent. The concentration of the extracted chromium (VI) in the organic layer was measured spectrophotometrically at a wavelength maximum of 366 nm and the organic layer was characterized using FT-IR spectroscopy. The influence of various analytical parameters such as pH, aqueous phase volume, equilibration time, interfering ions etc. has been studied in detail. The extracted chromium (VI) was back extracted into the aqueous phase to the non-toxic chromium (III) using ascorbic acid. The calibration graph was linear in the range of 0-2 microg mL(-1) chromium (VI) with a relative standard deviation of 2.4%. A detection limit of 0.25 microg in 25 mL aqueous phase volume could be achieved and the validity of the proposed method has been checked by applying it to synthetic mixtures, spiked water sample, electroplating wastewater and certified reference material BCR-715."
1509793,Gokhale et al. 2009,Modeling of chromium (VI) biosorption by immobilized Spirulina platensis in packed column,"This study describes biosorption of chromium (VI) by immobilized Spirulina platensis, in calcium alginate beads. Three aspects viz. optimization of bead parameters, equilibrium conditions and packed column operation were studied and subsequently modeled. Under optimized bead diameter (2.6mm), calcium alginate concentration (2%, w/v) and biomass loading (2.6%, w/v) maximum biosorption was achieved. 140 g l(-1) loading of optimized beads resulted in 99% adsorption of chromium (VI) ions from an aqueous solution containing 100 mg l(-1) of chromium (VI). The quantitative chromium (VI) uptake was effectively described by Freundlich adsorption isotherm. The immobilized S. platensis beads were further used in a packed bed column wherein the effects of bed height, feed flow rate, inlet chromium (VI) ion concentration were studied by assessing breakthrough time. The performance data were tested for various models fitting in order to predict scale up-design parameters such as breakthrough time and column height. Results were encouraging.","Modeling of chromium (VI) biosorption by immobilized Spirulina platensis in packed column Abs: This study describes biosorption of chromium (VI) by immobilized Spirulina platensis, in calcium alginate beads. Three aspects viz. optimization of bead parameters, equilibrium conditions and packed column operation were studied and subsequently modeled. Under optimized bead diameter (2.6mm), calcium alginate concentration (2%, w/v) and biomass loading (2.6%, w/v) maximum biosorption was achieved. 140 g l(-1) loading of optimized beads resulted in 99% adsorption of chromium (VI) ions from an aqueous solution containing 100 mg l(-1) of chromium (VI). The quantitative chromium (VI) uptake was effectively described by Freundlich adsorption isotherm. The immobilized S. platensis beads were further used in a packed bed column wherein the effects of bed height, feed flow rate, inlet chromium (VI) ion concentration were studied by assessing breakthrough time. The performance data were tested for various models fitting in order to predict scale up-design parameters such as breakthrough time and column height. Results were encouraging."
1509792,Ouerdane et al. 2009,General equation for multiple spiking isotope dilution mass spectrometry,"Isotope dilution is a well-known primary ratio method of quantitative analysis that yields good-quality metrological results. Many equations have been proposed to calculate the amount of substance from the isotope ratio measurements, and these have been used successfully for more than a half-century. Decades ago, isotope dilution equations were extended to correct for analyte formation during analysis, which is especially apparent in the analysis of methylmercury or chromium(VI). Considering only methods for the determination of these two analytes, many variables that are involved must be considered (for example, the extent of analyte formation, the number of isotopes monitored for each analyte, the number of substances, or the nature of mass spectra (elemental versus molecular)). To date, no master equation that can adequately address all of these aspects of the problem has been proposed. In this manuscript, we propose a general equation for isotope dilution.","General equation for multiple spiking isotope dilution mass spectrometry Abs: Isotope dilution is a well-known primary ratio method of quantitative analysis that yields good-quality metrological results. Many equations have been proposed to calculate the amount of substance from the isotope ratio measurements, and these have been used successfully for more than a half-century. Decades ago, isotope dilution equations were extended to correct for analyte formation during analysis, which is especially apparent in the analysis of methylmercury or chromium(VI). Considering only methods for the determination of these two analytes, many variables that are involved must be considered (for example, the extent of analyte formation, the number of isotopes monitored for each analyte, the number of substances, or the nature of mass spectra (elemental versus molecular)). To date, no master equation that can adequately address all of these aspects of the problem has been proposed. In this manuscript, we propose a general equation for isotope dilution."
1509791,Duran et al. 2009,A novel method for speciation of chromium: coprecipitation without carrier element by using a triazole derivative,"A coprecipitation method has been established for speciation of chromium(III) and chromium(VI) in real samples. The procedure is based on the coprecipitation of Cr(III), by using a new organic coprecipitant, 3-phenyl-4-o-hydroxybenzyl-idenamino-4,5-dihydro-1,2,4-triazole-5-one, without adding any carrier element. After reduction of Cr(VI) by concentrated H2SO4 and ethanol, the method was applied to the determination of total Cr. The level of Cr(VI) was calculated by the difference of total Cr and Cr(III) levels. For optimum recovery of Cr(III), different analytical factors such as pH, amount of coprecipitant, centrifugation rate and time, and effect of sample volume, were investigated. The influences of some anions, cations, and transition metals on the recoveries were also investigated, and no significant interferences were observed. The preconcentration factor was 100. The detection limit based on 3 times standard deviation (sigma) of the blank (n = 10) for Cr(III) was 0.50 microg/L. In order to evaluate the accuracy of the method, certified reference materials (CRM-TMDW-500 Drinking Water and National Institute of Standards and Technology Standard Reference Material 1573a Tomato Leaves) were analyzed, and the results obtained were in good agreement with certified values. The presented procedure was applied for Cr speciation in various solid and liquid samples with successful results.","A novel method for speciation of chromium: coprecipitation without carrier element by using a triazole derivative Abs: A coprecipitation method has been established for speciation of chromium(III) and chromium(VI) in real samples. The procedure is based on the coprecipitation of Cr(III), by using a new organic coprecipitant, 3-phenyl-4-o-hydroxybenzyl-idenamino-4,5-dihydro-1,2,4-triazole-5-one, without adding any carrier element. After reduction of Cr(VI) by concentrated H2SO4 and ethanol, the method was applied to the determination of total Cr. The level of Cr(VI) was calculated by the difference of total Cr and Cr(III) levels. For optimum recovery of Cr(III), different analytical factors such as pH, amount of coprecipitant, centrifugation rate and time, and effect of sample volume, were investigated. The influences of some anions, cations, and transition metals on the recoveries were also investigated, and no significant interferences were observed. The preconcentration factor was 100. The detection limit based on 3 times standard deviation (sigma) of the blank (n = 10) for Cr(III) was 0.50 microg/L. In order to evaluate the accuracy of the method, certified reference materials (CRM-TMDW-500 Drinking Water and National Institute of Standards and Technology Standard Reference Material 1573a Tomato Leaves) were analyzed, and the results obtained were in good agreement with certified values. The presented procedure was applied for Cr speciation in various solid and liquid samples with successful results."
1509790,Fan et al. 2009,"An organic-reagent-free method for determination of chromium(VI) in steel alloys, sewage sludge and wastewater","One of the active areas of green chemistry research and development is in the development of new analytical methods and techniques that reduce and eliminate the use and generation of hazardous substances. In this work, a rapid and organic-reagent-free method was developed for the determination of chromium(VI) by sequential injection analysis (SIA). The method was based on the detection of a blue unstable intermediate compound resulting from the reaction of Cr(VI) with hydrogen peroxide (H(2)O(2)) in acidic medium. H(2)O(2) and its reaction products were environmentally friendly, and chromogenic reagents and organic solvents were not used in the proposed method. Different SIA parameters have been optimized and used to obtain the analytical figures of merit. Under the optimum experimental conditions, the linear range for Cr(VI) was 0.5-100.0 microg mL(-1), and the detection limit was 0.16 microg mL(-1). The sample throughput was 80 h(-1), and the total volume of only 145 microL was consumed in each determination of Cr(VI). The method was applied for the determination of Cr(VI) in seven real samples, including alloy steel, sewage sludge and wastewater samples, and the results were compared with those obtained by atomic absorption spectrometry as well as with the certified value of Cr(VI) in standard reference material. Statistical analysis revealed that there was no significant difference at 95% confidence level.","An organic-reagent-free method for determination of chromium(VI) in steel alloys, sewage sludge and wastewater Abs: One of the active areas of green chemistry research and development is in the development of new analytical methods and techniques that reduce and eliminate the use and generation of hazardous substances. In this work, a rapid and organic-reagent-free method was developed for the determination of chromium(VI) by sequential injection analysis (SIA). The method was based on the detection of a blue unstable intermediate compound resulting from the reaction of Cr(VI) with hydrogen peroxide (H(2)O(2)) in acidic medium. H(2)O(2) and its reaction products were environmentally friendly, and chromogenic reagents and organic solvents were not used in the proposed method. Different SIA parameters have been optimized and used to obtain the analytical figures of merit. Under the optimum experimental conditions, the linear range for Cr(VI) was 0.5-100.0 microg mL(-1), and the detection limit was 0.16 microg mL(-1). The sample throughput was 80 h(-1), and the total volume of only 145 microL was consumed in each determination of Cr(VI). The method was applied for the determination of Cr(VI) in seven real samples, including alloy steel, sewage sludge and wastewater samples, and the results were compared with those obtained by atomic absorption spectrometry as well as with the certified value of Cr(VI) in standard reference material. Statistical analysis revealed that there was no significant difference at 95% confidence level."
1509789,Maiti et al. 2009,Determination of kinetic parameters in the biosorption of Cr (VI) on immobilized Bacillus cereus M(1)(16) in a continuous packed bed column reactor,"Due to technological advancement, environment suffers from untreated toxic heavy metal bearing effluent coming from different industries. Chromium (VI) is one of those heavy metals having adverse impact on ecological balance, human, and plant health because of its carcinogenic properties. Biosorption is presented as an alternative to traditional technologies which are costly and inefficient for treatment of industrial wastes containing low amount of heavy metals. In this study, bioremediation of Cr (VI) ions by immobilized Bacillus cereus M(1) (16) was investigated in a laboratory scale packed bed up-flow column reactor. The effect of important parameters, such as the inlet flow rate, influent concentration, and effective bed height, has been studied. External mass transfer, surface adsorption, and intrabead mass transfer were also studied to conclude the rate limiting step for removal of Cr (VI) and to determine the process parameters which are important for biosorption optimization. The external mass transfer coefficient was calculated at different flow rates (6.51 x 10(-2) to 7.58 x 10(-2) cm/min). Using the model, the surface adsorption rate constant (k(ad)) and the intrabead mass transfer coefficient (k (i)) were predicted as 0.0267 x 10(-3) and 0.7465 x 10(-3) l/g/min, respectively. Both are much lower than the external mass transfer coefficient (k(e)). The surface adsorption phenomenon is acting as the rate-limiting step due to its high resistance for removal of Cr (VI).","Determination of kinetic parameters in the biosorption of Cr (VI) on immobilized Bacillus cereus M(1)(16) in a continuous packed bed column reactor Abs: Due to technological advancement, environment suffers from untreated toxic heavy metal bearing effluent coming from different industries. Chromium (VI) is one of those heavy metals having adverse impact on ecological balance, human, and plant health because of its carcinogenic properties. Biosorption is presented as an alternative to traditional technologies which are costly and inefficient for treatment of industrial wastes containing low amount of heavy metals. In this study, bioremediation of Cr (VI) ions by immobilized Bacillus cereus M(1) (16) was investigated in a laboratory scale packed bed up-flow column reactor. The effect of important parameters, such as the inlet flow rate, influent concentration, and effective bed height, has been studied. External mass transfer, surface adsorption, and intrabead mass transfer were also studied to conclude the rate limiting step for removal of Cr (VI) and to determine the process parameters which are important for biosorption optimization. The external mass transfer coefficient was calculated at different flow rates (6.51 x 10(-2) to 7.58 x 10(-2) cm/min). Using the model, the surface adsorption rate constant (k(ad)) and the intrabead mass transfer coefficient (k (i)) were predicted as 0.0267 x 10(-3) and 0.7465 x 10(-3) l/g/min, respectively. Both are much lower than the external mass transfer coefficient (k(e)). The surface adsorption phenomenon is acting as the rate-limiting step due to its high resistance for removal of Cr (VI)."
1509788,Mouedhen et al. 2009,Electrochemical removal of Cr(VI) from aqueous media using iron and aluminum as electrode materials: towards a better understanding of the involved phenomena,"In the present work, electrocoagulation process with iron and aluminum electrodes was investigated to deepen the understanding of the mechanism of hexavalent chromium (Cr(VI)) removal. Electrocoagulation treatment efficiency was studied with regards to the abatement of Cr(VI) and the resulting species-namely Cr(III), Fe(II) and/or Fe(III). Unlike iron, aluminum electrodes were found to be unsatisfactory for Cr(VI) removal. To elucidate the removal mechanism of hexavalent chromium, different anode/cathode materials and configurations (Fe/Fe, Pt Ti (platinized titanium)/Fe, Al/Al and Pt Ti/Al) were considered. At nearly neutral pH and considering aluminum electrodes, both electrochemical reduction (Cr(VI) to Cr(III)) at the cathode surface and adsorption on Al(OH)(3) floc mechanisms were responsible for Cr(VI) exhaustion. However, the contribution of the two mechanisms to Cr(VI) removal was not discriminated. On the other hand, in the case of iron electrodes, even though electrochemical reduction may contribute to chromium removal, its influence seemed to be minor since the effect was confined to less than 5% of the removal efficiency. Hence, there was essentially one real root for the reduction of Cr(VI) by electrocoagulation with iron electrodes, and it was proven to be the chemical reduction by Fe(II) anodically generated. Moreover, the resulting Cr(III) was quickly removed from solution, via efficient precipitation as Cr(OH)(3) hydroxides. Besides, the electrodissolved iron remained at low level owing to the precipitation of Fe(OH)(2) and/or Fe(OH)(3). Although chemical reduction by Fe(II) predominantly governed the removal of Cr(VI), acidic pH media was found to promote electrochemical reduction of hexavalent chromium at the cathode and accordingly to enhance Cr(VI) removal efficiency. In contrast, a delay of Cr(III) precipitation and a contamination of the electrolyte by electrodissolved iron were observed under acidic conditions. The effect of supporting electrolyte (Na(2)SO(4) and NaCl) on chromium removal was also studied. No conspicuous disparity in the treatment efficiency was noted under the electrocoagulation conditions used.","Electrochemical removal of Cr(VI) from aqueous media using iron and aluminum as electrode materials: towards a better understanding of the involved phenomena Abs: In the present work, electrocoagulation process with iron and aluminum electrodes was investigated to deepen the understanding of the mechanism of hexavalent chromium (Cr(VI)) removal. Electrocoagulation treatment efficiency was studied with regards to the abatement of Cr(VI) and the resulting species-namely Cr(III), Fe(II) and/or Fe(III). Unlike iron, aluminum electrodes were found to be unsatisfactory for Cr(VI) removal. To elucidate the removal mechanism of hexavalent chromium, different anode/cathode materials and configurations (Fe/Fe, Pt Ti (platinized titanium)/Fe, Al/Al and Pt Ti/Al) were considered. At nearly neutral pH and considering aluminum electrodes, both electrochemical reduction (Cr(VI) to Cr(III)) at the cathode surface and adsorption on Al(OH)(3) floc mechanisms were responsible for Cr(VI) exhaustion. However, the contribution of the two mechanisms to Cr(VI) removal was not discriminated. On the other hand, in the case of iron electrodes, even though electrochemical reduction may contribute to chromium removal, its influence seemed to be minor since the effect was confined to less than 5% of the removal efficiency. Hence, there was essentially one real root for the reduction of Cr(VI) by electrocoagulation with iron electrodes, and it was proven to be the chemical reduction by Fe(II) anodically generated. Moreover, the resulting Cr(III) was quickly removed from solution, via efficient precipitation as Cr(OH)(3) hydroxides. Besides, the electrodissolved iron remained at low level owing to the precipitation of Fe(OH)(2) and/or Fe(OH)(3). Although chemical reduction by Fe(II) predominantly governed the removal of Cr(VI), acidic pH media was found to promote electrochemical reduction of hexavalent chromium at the cathode and accordingly to enhance Cr(VI) removal efficiency. In contrast, a delay of Cr(III) precipitation and a contamination of the electrolyte by electrodissolved iron were observed under acidic conditions. The effect of supporting electrolyte (Na(2)SO(4) and NaCl) on chromium removal was also studied. No conspicuous disparity in the treatment efficiency was noted under the electrocoagulation conditions used."
1509787,Kaur and  Malik 2009,Speciation of chromium metal ions by RP-HPLC,"A high-performance liquid chromatographic method with UV detection, based on chelation with morpholine-4-carbodithioate (MDTC), has been developed for the speciation of chromium. Simultaneous preconcentration of Cr(III) and Cr(VI) in aqueous solutions was achieved by extraction of metal species in chloroform as MDTC complexes. The separation of MDTC chelates of Cr(III) and Cr(VI) was realized on a C18 column with the use of acetonitrile-water (70:30) at a flow rate of 1.0 mL/min. The Cr(III) showed a single peak in chromatogram due to Cr(MDTC)(3), and Cr(VI) showed two peaks due to the formation of Cr(MDTC)(3) and Cr(MDTC)(2)(OMDTC). These two complexes were separated with different retention times at 5.4 and 4.3 min, respectively. The developed method can be used for rapid routine determination of chromium species with high precision and reliability. The method was validated by applying to various synthetic binary mixtures prepared by spiking Cr(III) and Cr(VI) in tap water.","Speciation of chromium metal ions by RP-HPLC Abs: A high-performance liquid chromatographic method with UV detection, based on chelation with morpholine-4-carbodithioate (MDTC), has been developed for the speciation of chromium. Simultaneous preconcentration of Cr(III) and Cr(VI) in aqueous solutions was achieved by extraction of metal species in chloroform as MDTC complexes. The separation of MDTC chelates of Cr(III) and Cr(VI) was realized on a C18 column with the use of acetonitrile-water (70:30) at a flow rate of 1.0 mL/min. The Cr(III) showed a single peak in chromatogram due to Cr(MDTC)(3), and Cr(VI) showed two peaks due to the formation of Cr(MDTC)(3) and Cr(MDTC)(2)(OMDTC). These two complexes were separated with different retention times at 5.4 and 4.3 min, respectively. The developed method can be used for rapid routine determination of chromium species with high precision and reliability. The method was validated by applying to various synthetic binary mixtures prepared by spiking Cr(III) and Cr(VI) in tap water."
1509786,Bhowmick et al. 2009,A low-GC Gram-positive Thermoanaerobacter-like bacterium isolated from an Indian hot spring contains Cr(VI) reduction activity both in the membrane and cytoplasm,"<strong>AIM: </strong>Characterization of an anaerobic thermophilic bacterium and subcellular localization of its Cr(VI)-reducing activity for potential bioremediation applications.<br /><br /><strong>METHODS AND RESULTS: </strong>16S rRNA gene sequence-based analyses of bacterial strains isolated from sediment samples of a Bakreshwar (India) hot spring, enriched anaerobically in iron-reducing medium, found them to be 86-96% similar to reported Thermoanaerobacter strains. The most efficient iron reducer among these, BSB-33, could also reduce Cr(VI) at an optimum temperature of 60 degrees C and pH 6.5. Filtered culture medium could reduce Cr(VI) but not Fe(III). Cell-free extracts reduced Cr(VI) inefficiently under aerobic conditions but efficiently anaerobically. Fractionation of the cell-free extracts showed that chromium reduction activity was present in both the cytoplasm and membrane.<br /><br /><strong>CONCLUSIONS: </strong>BSB-33 reduced Fe(III) and Cr(VI) anaerobically at 60 degrees C optimally. After fractionation, the reducing activity of Cr(VI) was found in both cytoplasmic and membrane fractions.<br /><br /><strong>SIGNIFICANCE AND IMPACT OF THE STUDY: </strong>To the best of our knowledge, this is the first systematic study of anaerobic Cr(VI) reduction by a gram-positive thermophilic micro-organism and, in contrast to our results, none of the earlier reports has mentioned Cr(VI)-reducing activity to be present both in the cytoplasm and membrane of an organism. The strain may offer itself as a potential candidate for bioremediation.","A low-GC Gram-positive Thermoanaerobacter-like bacterium isolated from an Indian hot spring contains Cr(VI) reduction activity both in the membrane and cytoplasm Abs: <strong>AIM: </strong>Characterization of an anaerobic thermophilic bacterium and subcellular localization of its Cr(VI)-reducing activity for potential bioremediation applications.<br /><br /><strong>METHODS AND RESULTS: </strong>16S rRNA gene sequence-based analyses of bacterial strains isolated from sediment samples of a Bakreshwar (India) hot spring, enriched anaerobically in iron-reducing medium, found them to be 86-96% similar to reported Thermoanaerobacter strains. The most efficient iron reducer among these, BSB-33, could also reduce Cr(VI) at an optimum temperature of 60 degrees C and pH 6.5. Filtered culture medium could reduce Cr(VI) but not Fe(III). Cell-free extracts reduced Cr(VI) inefficiently under aerobic conditions but efficiently anaerobically. Fractionation of the cell-free extracts showed that chromium reduction activity was present in both the cytoplasm and membrane.<br /><br /><strong>CONCLUSIONS: </strong>BSB-33 reduced Fe(III) and Cr(VI) anaerobically at 60 degrees C optimally. After fractionation, the reducing activity of Cr(VI) was found in both cytoplasmic and membrane fractions.<br /><br /><strong>SIGNIFICANCE AND IMPACT OF THE STUDY: </strong>To the best of our knowledge, this is the first systematic study of anaerobic Cr(VI) reduction by a gram-positive thermophilic micro-organism and, in contrast to our results, none of the earlier reports has mentioned Cr(VI)-reducing activity to be present both in the cytoplasm and membrane of an organism. The strain may offer itself as a potential candidate for bioremediation."
1509785,Ewais et al. 2009,Inner-sphere oxidation of ternary iminodiacetatochromium(III) complexes involving DL-valine and L-arginine as secondary ligands. Isokinetic relationship for the oxidation of ternary iminodiacetato-chromium(III) complexes by periodate,"<strong>BACKGROUND: </strong>In this paper, the kinetics of oxidation of [CrIII(HIDA)(Val)(H2O)2]+ and [CrIII(HIDA)(Arg)(H2O)2]+ (HIDA = iminodiacetic acid, Val = DL-valine and Arg = L-arginine) were studied. The choice of ternary complexes was attributed to two considerations. Firstly, in order to study the effect of the secondary ligands DL-valine and L-arginine on the stability of binary complex [CrIII(HIDA)(IDA)(H2O)] towards oxidation. Secondly, transition metal ternary complexes have received particular focus and have been employed in mapping protein surfaces as probes for biological redox centers and in protein capture for both purification and study.<br /><br /><strong>RESULTS: </strong>The results have shown that the reaction is first order with respect to both [IO4(-)] and the complex concentration, and the rate increases over the pH range 2.62 - 3.68 in both cases. The experimental rate law is consistent with a mechanism in which both the deprotonated forms of the complexes [CrIII(IDA)(Val)(H2O)2] and [CrIII(IDA)(Arg)(H2O)2] are significantly more reactive than the conjugate acids. The value of the intramolecular electron transfer rate constant for the oxidation of [CrIII(HIDA)(Arg)(H2O)2]+, k3 (1.82 x 10(-3) s(-1)), is greater than the value of k1 (1.22 x 10(-3) s(-1)) for the oxidation of [CrIII(HIDA)(Val)(H2O)2]+ at 45.0 degrees C and I = 0.20 mol dm(-3). It is proposed that electron transfer proceeds through an inner-sphere mechanism via coordination of IO4(-) to chromium(III).<br /><br /><strong>CONCLUSION: </strong>The oxidation of [CrIII(HIDA)(Val)(H2O)2]+ and [CrIII(HIDA)(Arg)(H2O)2]+ by periodate may proceed through an inner-sphere mechanism via two electron transfer giving chromium(VI). The value of the intramolecular electron transfer rate constant for the oxidation of [CrIII(HIDA)(Arg)(H2O)2]+, k3, is greater than the value of k1 for the oxidation of [CrIII(HIDA)(Val)(H2O)2]+. A common mechanism for the oxidation of ternary iminodiacetatochromium(III) complexes by periodate is proposed, and this is supported by an excellent isokinetic relationship between DeltaH* and DeltaS* values for these reactions.","Inner-sphere oxidation of ternary iminodiacetatochromium(III) complexes involving DL-valine and L-arginine as secondary ligands. Isokinetic relationship for the oxidation of ternary iminodiacetato-chromium(III) complexes by periodate Abs: <strong>BACKGROUND: </strong>In this paper, the kinetics of oxidation of [CrIII(HIDA)(Val)(H2O)2]+ and [CrIII(HIDA)(Arg)(H2O)2]+ (HIDA = iminodiacetic acid, Val = DL-valine and Arg = L-arginine) were studied. The choice of ternary complexes was attributed to two considerations. Firstly, in order to study the effect of the secondary ligands DL-valine and L-arginine on the stability of binary complex [CrIII(HIDA)(IDA)(H2O)] towards oxidation. Secondly, transition metal ternary complexes have received particular focus and have been employed in mapping protein surfaces as probes for biological redox centers and in protein capture for both purification and study.<br /><br /><strong>RESULTS: </strong>The results have shown that the reaction is first order with respect to both [IO4(-)] and the complex concentration, and the rate increases over the pH range 2.62 - 3.68 in both cases. The experimental rate law is consistent with a mechanism in which both the deprotonated forms of the complexes [CrIII(IDA)(Val)(H2O)2] and [CrIII(IDA)(Arg)(H2O)2] are significantly more reactive than the conjugate acids. The value of the intramolecular electron transfer rate constant for the oxidation of [CrIII(HIDA)(Arg)(H2O)2]+, k3 (1.82 x 10(-3) s(-1)), is greater than the value of k1 (1.22 x 10(-3) s(-1)) for the oxidation of [CrIII(HIDA)(Val)(H2O)2]+ at 45.0 degrees C and I = 0.20 mol dm(-3). It is proposed that electron transfer proceeds through an inner-sphere mechanism via coordination of IO4(-) to chromium(III).<br /><br /><strong>CONCLUSION: </strong>The oxidation of [CrIII(HIDA)(Val)(H2O)2]+ and [CrIII(HIDA)(Arg)(H2O)2]+ by periodate may proceed through an inner-sphere mechanism via two electron transfer giving chromium(VI). The value of the intramolecular electron transfer rate constant for the oxidation of [CrIII(HIDA)(Arg)(H2O)2]+, k3, is greater than the value of k1 for the oxidation of [CrIII(HIDA)(Val)(H2O)2]+. A common mechanism for the oxidation of ternary iminodiacetatochromium(III) complexes by periodate is proposed, and this is supported by an excellent isokinetic relationship between DeltaH* and DeltaS* values for these reactions."
1509784,Silva et al. 2009,Ecotoxicity tests using the green algae Chlorella vulgaris--a useful tool in hazardous effluents management,"The treatment efficiency of laboratory wastewaters was evaluated and ecotoxicity tests with Chlorella vulgaris were performed on them to assess the safety of their environmental discharge. For chemical oxygen demand wastewaters, chromium (VI), mercury (II) and silver were efficiently removed by chemical treatments. A reduction of ecotoxicity was achieved; nevertheless, an EC50 (effective concentration that causes a 50% inhibition in the algae growth) of 1.5% (v/v) indicated still high level of ecotoxicity. For chloride determination wastewaters, an efficient reduction of chromium and silver was achieved after treatment. Regarding the reduction of ecotoxicity observed, EC50 increased from 0.059% to 0.5%, only a 0.02% concentration in the aquatic environment would guarantee no effects. Wastewaters containing phenanthroline/iron (II) complex were treated by chemical oxidation. Treatment was satisfactory concerning chemical parameters, although an increase in ecotoxicity was observed (EC50 reduced from 0.31% to 0.21%). The wastes from the kinetic study of persulphate and iodide reaction were treated with sodium bisulphite until colour was removed. Although they did not reveal significant ecotoxicity, only over 1% of the untreated waste produced observable effects over algae. Therefore, ecotoxicity tests could be considered a useful tool not only in laboratory effluents treatment, as shown, but also in hazardous wastewaters management.","Ecotoxicity tests using the green algae Chlorella vulgaris--a useful tool in hazardous effluents management Abs: The treatment efficiency of laboratory wastewaters was evaluated and ecotoxicity tests with Chlorella vulgaris were performed on them to assess the safety of their environmental discharge. For chemical oxygen demand wastewaters, chromium (VI), mercury (II) and silver were efficiently removed by chemical treatments. A reduction of ecotoxicity was achieved; nevertheless, an EC50 (effective concentration that causes a 50% inhibition in the algae growth) of 1.5% (v/v) indicated still high level of ecotoxicity. For chloride determination wastewaters, an efficient reduction of chromium and silver was achieved after treatment. Regarding the reduction of ecotoxicity observed, EC50 increased from 0.059% to 0.5%, only a 0.02% concentration in the aquatic environment would guarantee no effects. Wastewaters containing phenanthroline/iron (II) complex were treated by chemical oxidation. Treatment was satisfactory concerning chemical parameters, although an increase in ecotoxicity was observed (EC50 reduced from 0.31% to 0.21%). The wastes from the kinetic study of persulphate and iodide reaction were treated with sodium bisulphite until colour was removed. Although they did not reveal significant ecotoxicity, only over 1% of the untreated waste produced observable effects over algae. Therefore, ecotoxicity tests could be considered a useful tool not only in laboratory effluents treatment, as shown, but also in hazardous wastewaters management."
1509783,Memon et al. 2009,Banana peel: a green and economical sorbent for the selective removal of Cr(VI) from industrial wastewater,"This study describes the use of banana peel, a commonly produced fruit waste, for the removal of Cr(VI) from industrial wastewater. The parameters pH, contact time, initial metal ion concentration, and temperature were investigated and the conditions resulting in rapid and efficient adsorption (95% within 10 min) were determined. The binding of metal ions was found to be pH dependent with the optimal sorption occurring at pH 2. The retained species were eluted with 5 mL of 2M H(2)SO(4). To elucidate the mechanism of the process, total amounts of chromium and Cr(VI) were analyzed using flame atomic absorption and ultraviolet-visible (UV-vis) spectroscopic techniques, respectively. The Langmuir and Dubinin-Radushkevich (D-R) isotherms were used to describe the partitioning behavior for the system at different temperatures. Kinetics and thermodynamics of Cr(VI) removal by banana peel were also studied. The influence of diverse ions on the sorption behavior revealed that only Fe(II) ions (of those tested) suppressed the sorption of Cr(VI) ions to some extent. The method was applied for the removal of Cr(VI) from industrial wastewater.","Banana peel: a green and economical sorbent for the selective removal of Cr(VI) from industrial wastewater Abs: This study describes the use of banana peel, a commonly produced fruit waste, for the removal of Cr(VI) from industrial wastewater. The parameters pH, contact time, initial metal ion concentration, and temperature were investigated and the conditions resulting in rapid and efficient adsorption (95% within 10 min) were determined. The binding of metal ions was found to be pH dependent with the optimal sorption occurring at pH 2. The retained species were eluted with 5 mL of 2M H(2)SO(4). To elucidate the mechanism of the process, total amounts of chromium and Cr(VI) were analyzed using flame atomic absorption and ultraviolet-visible (UV-vis) spectroscopic techniques, respectively. The Langmuir and Dubinin-Radushkevich (D-R) isotherms were used to describe the partitioning behavior for the system at different temperatures. Kinetics and thermodynamics of Cr(VI) removal by banana peel were also studied. The influence of diverse ions on the sorption behavior revealed that only Fe(II) ions (of those tested) suppressed the sorption of Cr(VI) ions to some extent. The method was applied for the removal of Cr(VI) from industrial wastewater."
1509782,Gomes and  Asaeda 2009,Phycoremediation of Chromium (VI) by Nitella and impact of calcium encrustation,"This article discusses the applicability of the Charophyte, Nitella pseudoflabellata in the remediation of Cr (VI) contaminated waters at different calcifying potentials. Its growth was found to be positively correlated with Ca in water (CaW), but marginally significant in the presence of Cr (VI) in water (CrW). High CaW resulted in calcite encrustation on the plant cell wall. CaW was found to be aiding Cr (VI) fixation in the long run, as this correlated positively with both CaW and CrW. However, Ca interfered with passive Cr (VI) accumulation in live plant matter at low CrW concentrations (&lt;or=0.2mg/L). Biosorption by dead plant matter seemed to be the major mechanism as the dead plant organs contained &gt;1mg/g Cr dry weight of plant. Cr (VI) concentrations greater than 0.4 mg/L were too toxic, showing maximum quantum efficiency of PSII photochemistry (F(v)/F(m)) values&lt;0.63. The opposite was noticed (F(v)/F(m)&gt;0.76) when Cr (VI) was less than 0.2mg/L. Elongation curve patterns based on shoot lengths showed similar scenarios. In all cases high CaW units with calcite encrustation found to be least affected by Cr (VI) toxicity. Optimum remediation was obtained using a combination of high Ca and Cr (VI) in the case of passive (short-term) operation and low Ca and Cr (VI) for active (long-term) operation. Under the passive scenario, plants accumulated above 1.2mg/g Cr dry weight whereas in the active case, accumulation was 0.8 mg/g Cr dry weight. We conclude that Nitella-mediated Cr (VI) remediation is a promising technique within the range and conditions investigated.","Phycoremediation of Chromium (VI) by Nitella and impact of calcium encrustation Abs: This article discusses the applicability of the Charophyte, Nitella pseudoflabellata in the remediation of Cr (VI) contaminated waters at different calcifying potentials. Its growth was found to be positively correlated with Ca in water (CaW), but marginally significant in the presence of Cr (VI) in water (CrW). High CaW resulted in calcite encrustation on the plant cell wall. CaW was found to be aiding Cr (VI) fixation in the long run, as this correlated positively with both CaW and CrW. However, Ca interfered with passive Cr (VI) accumulation in live plant matter at low CrW concentrations (&lt;or=0.2mg/L). Biosorption by dead plant matter seemed to be the major mechanism as the dead plant organs contained &gt;1mg/g Cr dry weight of plant. Cr (VI) concentrations greater than 0.4 mg/L were too toxic, showing maximum quantum efficiency of PSII photochemistry (F(v)/F(m)) values&lt;0.63. The opposite was noticed (F(v)/F(m)&gt;0.76) when Cr (VI) was less than 0.2mg/L. Elongation curve patterns based on shoot lengths showed similar scenarios. In all cases high CaW units with calcite encrustation found to be least affected by Cr (VI) toxicity. Optimum remediation was obtained using a combination of high Ca and Cr (VI) in the case of passive (short-term) operation and low Ca and Cr (VI) for active (long-term) operation. Under the passive scenario, plants accumulated above 1.2mg/g Cr dry weight whereas in the active case, accumulation was 0.8 mg/g Cr dry weight. We conclude that Nitella-mediated Cr (VI) remediation is a promising technique within the range and conditions investigated."
1509781,Das et al. 2009,Structural and nanomechanical properties of Termitomyces clypeatus cell wall and its interaction with chromium(VI),"Alterations of cell surface properties accompanying the complex life cycle of Termitomyces clypeatus have been monitored using atomic force microscopy (AFM). A new hyphae/mycelium is developed on cell division, and the cell wall of the mycelium undergoes a process of internal reorganization (or maturation) followed by morphological and chemical alterations. The changes of the surface ultrastructures during the growth process are correlated to the corresponding changes in relative viscoelasticity and rigidity of the cell wall by employing force spectroscopy. The cell wall rigidity and elasticity are found to be 0.34+/-0.02 N/m and 27.5+/-2.1 MPa, respectively, at the early logarithmic phase, on maturation increase to reach 0.81+/-0.08 N/m and 92.5+/-12 MPa, respectively, at the stationary phase, and thereafter decrease to 0.62+/-0.06 N/m and 61.6+/-6.6 MPa at the death phase. The alterations of the ultrastructural and nanomechanical properties of the cell surface as functions of growth phases affect the interaction involving chromium and T. clypeatus.","Structural and nanomechanical properties of Termitomyces clypeatus cell wall and its interaction with chromium(VI) Abs: Alterations of cell surface properties accompanying the complex life cycle of Termitomyces clypeatus have been monitored using atomic force microscopy (AFM). A new hyphae/mycelium is developed on cell division, and the cell wall of the mycelium undergoes a process of internal reorganization (or maturation) followed by morphological and chemical alterations. The changes of the surface ultrastructures during the growth process are correlated to the corresponding changes in relative viscoelasticity and rigidity of the cell wall by employing force spectroscopy. The cell wall rigidity and elasticity are found to be 0.34+/-0.02 N/m and 27.5+/-2.1 MPa, respectively, at the early logarithmic phase, on maturation increase to reach 0.81+/-0.08 N/m and 92.5+/-12 MPa, respectively, at the stationary phase, and thereafter decrease to 0.62+/-0.06 N/m and 61.6+/-6.6 MPa at the death phase. The alterations of the ultrastructural and nanomechanical properties of the cell surface as functions of growth phases affect the interaction involving chromium and T. clypeatus."
1509780,Kalidhasan et al. 2009,Extractive separation and determination of chromium in tannery effluents and electroplating waste water using tribenzylamine as the extractant,"A simple extractive separation method has been developed for the determination of chromium based on the extraction of Cr (VI) as its ion-pair with tribenzylamine (TBA). The ion-pair is extracted at acidic pH using toluene as the diluent. The concentration of chromium in the organic phase was measured spectrophotometrically at 309 nm. The influence of experimental variables such as pH, sample volume, equilibration time, diverse ions etc. has been studied in detail. The extracted chromium (VI) could be stripped to the aqueous phase using NaOH as the stripping agent. The extracts were characterized using FT-IR spectroscopy. A detection limit of 0.08 microg mL(-1) could be achieved and the validity of the method was checked in real tannery effluent, electroplating waste water and spiked water samples.","Extractive separation and determination of chromium in tannery effluents and electroplating waste water using tribenzylamine as the extractant Abs: A simple extractive separation method has been developed for the determination of chromium based on the extraction of Cr (VI) as its ion-pair with tribenzylamine (TBA). The ion-pair is extracted at acidic pH using toluene as the diluent. The concentration of chromium in the organic phase was measured spectrophotometrically at 309 nm. The influence of experimental variables such as pH, sample volume, equilibration time, diverse ions etc. has been studied in detail. The extracted chromium (VI) could be stripped to the aqueous phase using NaOH as the stripping agent. The extracts were characterized using FT-IR spectroscopy. A detection limit of 0.08 microg mL(-1) could be achieved and the validity of the method was checked in real tannery effluent, electroplating waste water and spiked water samples."
1509779,Bulut et al. 2009,"Carrier element-free coprecipitation (CEFC) method for the separation, preconcentration and speciation of chromium using an isatin derivative","A new, simple, rapid and sensitive separation, preconcentration and speciation procedure for chromium in environmental liquid and solid samples has been established. The present speciation procedure for Cr(III) and Cr(VI) is based on combination of carrier element-free coprecipitation (CEFC) and flame atomic absorption spectrometric (FAAS) determinations. In this method a newly synthesized organic coprecipitant, 5-chloro-3-[4-(trifluoromethoxy) phenylimino]indolin-2-one (CFMEPI), was used without adding any carrier element for coprecipitation of chromium(III). After reduction of chromium(VI) by concentrated H(2)SO(4) and ethanol, the procedure was applied for the determination of total chromium. Chromium(VI) was calculated as the difference between the amount of total chromium and chromium(III). The optimum conditions for coprecipitation and speciation processes were investigated on several commonly tested experimental parameters, such as pH of the solution, amount of coprecipitant, sample volume, etc. No considerable interference was observed from the other investigated anions and cations, which may be found in natural water samples. The preconcentration factor was found to be 40. The detection limit for chromium(III) corresponding to three times the standard deviation of the blank (N=10) was found 0.7 microg L(-1). The present procedure was successfully applied for speciation of chromium in several liquid and solid environmental samples. In order to support the accuracy of the method, the certified reference materials (CRM-TMDW-500 Drinking Water and CRM-SA-C Sandy Soil C) were analyzed, and standard APDC-MIBK liquid-liquid extraction method was performed. The results obtained were in good agreement with the certified values.","Carrier element-free coprecipitation (CEFC) method for the separation, preconcentration and speciation of chromium using an isatin derivative Abs: A new, simple, rapid and sensitive separation, preconcentration and speciation procedure for chromium in environmental liquid and solid samples has been established. The present speciation procedure for Cr(III) and Cr(VI) is based on combination of carrier element-free coprecipitation (CEFC) and flame atomic absorption spectrometric (FAAS) determinations. In this method a newly synthesized organic coprecipitant, 5-chloro-3-[4-(trifluoromethoxy) phenylimino]indolin-2-one (CFMEPI), was used without adding any carrier element for coprecipitation of chromium(III). After reduction of chromium(VI) by concentrated H(2)SO(4) and ethanol, the procedure was applied for the determination of total chromium. Chromium(VI) was calculated as the difference between the amount of total chromium and chromium(III). The optimum conditions for coprecipitation and speciation processes were investigated on several commonly tested experimental parameters, such as pH of the solution, amount of coprecipitant, sample volume, etc. No considerable interference was observed from the other investigated anions and cations, which may be found in natural water samples. The preconcentration factor was found to be 40. The detection limit for chromium(III) corresponding to three times the standard deviation of the blank (N=10) was found 0.7 microg L(-1). The present procedure was successfully applied for speciation of chromium in several liquid and solid environmental samples. In order to support the accuracy of the method, the certified reference materials (CRM-TMDW-500 Drinking Water and CRM-SA-C Sandy Soil C) were analyzed, and standard APDC-MIBK liquid-liquid extraction method was performed. The results obtained were in good agreement with the certified values."
1509778,Zhou et al. 2009,Evaluation of the potential cytotoxicity of metals associated with implanted biomaterials (I),"The present assessments of potential toxicity of metal ions (Al, Ni, Cr, V, and Ag) that construct the metallic biomaterials were carried out in vitro. By measurements of cell alkaline phosphatase (ALP) activity and reduction ability of cell methyl tetrazolium (MTT), the cytotoxicity of prevalence metallic biomaterials has been investigated. Furthermore, the poison and erosion of metal ions and atoms on human tissue are discussed. Research results indicated that trace Cr(VI) showed serious cytotoxicity and Ni as well as V are cytotoxic if the ion concentration in culture medium is over 100 micromol x L(-1) and 1 micromol x L(-1), respectively. A strange phenomenon is that Ag also is cytotoxic if the ion concentration is higher than 500 micromol x L(-1). Al ion is biphasic in cytotoxicity. At low ion concentration (&lt; 10 micromol x L(-1)), Al ions can stimulate cell proliferation, whereas at concentrations over 1,000 micromol x L(-1), cytotoxicity increases.","Evaluation of the potential cytotoxicity of metals associated with implanted biomaterials (I) Abs: The present assessments of potential toxicity of metal ions (Al, Ni, Cr, V, and Ag) that construct the metallic biomaterials were carried out in vitro. By measurements of cell alkaline phosphatase (ALP) activity and reduction ability of cell methyl tetrazolium (MTT), the cytotoxicity of prevalence metallic biomaterials has been investigated. Furthermore, the poison and erosion of metal ions and atoms on human tissue are discussed. Research results indicated that trace Cr(VI) showed serious cytotoxicity and Ni as well as V are cytotoxic if the ion concentration in culture medium is over 100 micromol x L(-1) and 1 micromol x L(-1), respectively. A strange phenomenon is that Ag also is cytotoxic if the ion concentration is higher than 500 micromol x L(-1). Al ion is biphasic in cytotoxicity. At low ion concentration (&lt; 10 micromol x L(-1)), Al ions can stimulate cell proliferation, whereas at concentrations over 1,000 micromol x L(-1), cytotoxicity increases."
1509777,Li et al. 2009,Opposing effects of inhibiting cap addition and cap methylation on polyadenylation during vesicular stomatitis virus mRNA synthesis,"The multifunctional large (L) polymerase protein of vesicular stomatitis virus (VSV) contains enzymatic activities essential for RNA synthesis, including mRNA cap addition and polyadenylation. We previously mapped amino acid residues G1154, T1157, H1227, and R1228, present within conserved region V (CRV) of L, as essential for mRNA cap addition. Here we show that alanine substitutions to these residues also affect 3'-end formation. Specifically, the cap-defective polymerases produced truncated transcripts that contained A-rich sequences at their 3' termini and predominantly terminated within the first 500 nucleotides (nt) of the N gene. To examine how the cap-defective polymerases respond to an authentic VSV termination and reinitiation signal present at each gene junction, we reconstituted RNA synthesis using templates that contained genes inserted (I) at the leader-N gene junction. The I genes ranged in size from 382 to 1,098 nt and were typically transcribed into full-length uncapped transcripts. In addition to lacking a cap structure, the full-length I transcripts synthesized by the cap-defective polymerases lacked an authentic polyadenylate tail and instead contained 0 to 24 A residues. Moreover, the cap-defective polymerases were also unable to copy efficiently the downstream gene. Thus, single amino acid substitutions in CRV of L protein that inhibit cap addition also inhibit polyadenylation and sequential transcription of the genome. In contrast, an amino acid substitution, K1651A, in CRVI of L protein that completely inhibits cap methylation results in the hyperpolyadenylation of mRNA. This work reveals that inhibiting cap addition and cap methylation have opposing effects on polyadenylation during VSV mRNA synthesis and provides evidence in support of a link between correct 5' cap formation and 3' polyadenylation.","Opposing effects of inhibiting cap addition and cap methylation on polyadenylation during vesicular stomatitis virus mRNA synthesis Abs: The multifunctional large (L) polymerase protein of vesicular stomatitis virus (VSV) contains enzymatic activities essential for RNA synthesis, including mRNA cap addition and polyadenylation. We previously mapped amino acid residues G1154, T1157, H1227, and R1228, present within conserved region V (CRV) of L, as essential for mRNA cap addition. Here we show that alanine substitutions to these residues also affect 3'-end formation. Specifically, the cap-defective polymerases produced truncated transcripts that contained A-rich sequences at their 3' termini and predominantly terminated within the first 500 nucleotides (nt) of the N gene. To examine how the cap-defective polymerases respond to an authentic VSV termination and reinitiation signal present at each gene junction, we reconstituted RNA synthesis using templates that contained genes inserted (I) at the leader-N gene junction. The I genes ranged in size from 382 to 1,098 nt and were typically transcribed into full-length uncapped transcripts. In addition to lacking a cap structure, the full-length I transcripts synthesized by the cap-defective polymerases lacked an authentic polyadenylate tail and instead contained 0 to 24 A residues. Moreover, the cap-defective polymerases were also unable to copy efficiently the downstream gene. Thus, single amino acid substitutions in CRV of L protein that inhibit cap addition also inhibit polyadenylation and sequential transcription of the genome. In contrast, an amino acid substitution, K1651A, in CRVI of L protein that completely inhibits cap methylation results in the hyperpolyadenylation of mRNA. This work reveals that inhibiting cap addition and cap methylation have opposing effects on polyadenylation during VSV mRNA synthesis and provides evidence in support of a link between correct 5' cap formation and 3' polyadenylation."
1509776,Pires et al. 2007,Speciation of chromium in natural waters by micropumping multicommutated light emitting diode photometry,"A simple and sensitive multicommutated flow procedure, implemented by employing a homemade light emitting diode (LED) based photometer, has been developed for the determination of chromium (VI) and total chromium in water. The flow system comprised a set of four solenoid micro-pumps, which were assembled to work as fluid propelling and as commutating devices. The core of the detection unit comprised a green LED source, a photodiode and a homemade flow cell of 100mm length and 2mm inner diameter. The photometric procedure for the speciation of chromium in natural waters was based on the reaction of Cr (VI) with 1,5-diphenylcarbazide. Cr (III) was previously oxidized to Cr (VI) and determined as the difference between total Cr and Cr (VI). After carrying out the assays to select the best operational conditions the features of the method included: a linear response ranging from 10 to 200mugl(-1) Cr (III) and Cr (VI) (r=0.999, n=7); limits of detection of 2.05 and 1.0mugl(-1) for Cr (III) and Cr (VI), respectively; a relative standard deviation lower than 2.0% (n=20) for a typical solution containing 50mugl(-1) Cr; a sampling throughput of 67 and 105 determinations per hour for total Cr and Cr (VI), respectively, and recovery values within the range of 93-108% for spiked concentrations of the order of 50mugl(-1).","Speciation of chromium in natural waters by micropumping multicommutated light emitting diode photometry Abs: A simple and sensitive multicommutated flow procedure, implemented by employing a homemade light emitting diode (LED) based photometer, has been developed for the determination of chromium (VI) and total chromium in water. The flow system comprised a set of four solenoid micro-pumps, which were assembled to work as fluid propelling and as commutating devices. The core of the detection unit comprised a green LED source, a photodiode and a homemade flow cell of 100mm length and 2mm inner diameter. The photometric procedure for the speciation of chromium in natural waters was based on the reaction of Cr (VI) with 1,5-diphenylcarbazide. Cr (III) was previously oxidized to Cr (VI) and determined as the difference between total Cr and Cr (VI). After carrying out the assays to select the best operational conditions the features of the method included: a linear response ranging from 10 to 200mugl(-1) Cr (III) and Cr (VI) (r=0.999, n=7); limits of detection of 2.05 and 1.0mugl(-1) for Cr (III) and Cr (VI), respectively; a relative standard deviation lower than 2.0% (n=20) for a typical solution containing 50mugl(-1) Cr; a sampling throughput of 67 and 105 determinations per hour for total Cr and Cr (VI), respectively, and recovery values within the range of 93-108% for spiked concentrations of the order of 50mugl(-1)."
1509775,Som-Aum et al. 2007,Determination of chromium(III) and total chromium using dual channels on glass chip with chemiluminescence detection,"A simple, rapid and sensitive method for the determination of chromium(III) and total chromium using the simple dual T channels on glass chip with negative pressure pumping system and chemiluminescence (CL) detection is presented. The CL reaction was based on luminol oxidation by hydrogen peroxide in basic aqueous solution catalyzed by chromium(III). Total chromium in form of chromium(III) was achieved after chromium(VI) was completely reduced by acidic sodium hydrogen sulfite. Total chromium could then be determined with the same strategy as the chromium(III). The CL reagent was composed of 1.0x10(-4)mol/L luminol, 1.0x10(-2)mol/L hydrogen peroxide and 0.10mol/L sodium bromide in 0.050mol/L carbonate buffer (pH 11.00). The 1.0x10(-2)mol/L ethylenediaminetetraacetic acid was added into the sample solution in order to improve the selectivity. Chromium(III) could be detected at a notably concentration of 1.6x10(-16)mol/L and a linear calibration curve was obtained from 1.0x10(-15) to 1.0x10(-13)mol/L. The sample and CL reagent consumption were only 15 and 20microL, respectively. The analysis time was less than 1 min per sample with the precision (%R.S.D.) was 4.7%. The proposed method has been applied successfully to the analysis of river water, mineral waters, drinking waters and tap water. Its performance was verified by the analysis of certified total chromium-reference materials and by recovery measurement on spiked synthetic seawater sample.","Determination of chromium(III) and total chromium using dual channels on glass chip with chemiluminescence detection Abs: A simple, rapid and sensitive method for the determination of chromium(III) and total chromium using the simple dual T channels on glass chip with negative pressure pumping system and chemiluminescence (CL) detection is presented. The CL reaction was based on luminol oxidation by hydrogen peroxide in basic aqueous solution catalyzed by chromium(III). Total chromium in form of chromium(III) was achieved after chromium(VI) was completely reduced by acidic sodium hydrogen sulfite. Total chromium could then be determined with the same strategy as the chromium(III). The CL reagent was composed of 1.0x10(-4)mol/L luminol, 1.0x10(-2)mol/L hydrogen peroxide and 0.10mol/L sodium bromide in 0.050mol/L carbonate buffer (pH 11.00). The 1.0x10(-2)mol/L ethylenediaminetetraacetic acid was added into the sample solution in order to improve the selectivity. Chromium(III) could be detected at a notably concentration of 1.6x10(-16)mol/L and a linear calibration curve was obtained from 1.0x10(-15) to 1.0x10(-13)mol/L. The sample and CL reagent consumption were only 15 and 20microL, respectively. The analysis time was less than 1 min per sample with the precision (%R.S.D.) was 4.7%. The proposed method has been applied successfully to the analysis of river water, mineral waters, drinking waters and tap water. Its performance was verified by the analysis of certified total chromium-reference materials and by recovery measurement on spiked synthetic seawater sample."
1509774,Real et al. 2007,Analysis of interferents by means a D-optimal screening design and calibration using partial least squares regression in the spectrophotometric determination of Cr(VI),"Using a central composite design, the signal of the process for the spectrophotometric determination of hexavalent chromium (lambda=543nm) is maximised and its variability minimised using as complexing agent 1,5-diphenylcarbazide in sufficiently acid medium. To analyse the interference of various analytes (Mo(VI), V(V), Fe(III) and Mn(VII)) on the Cr(VI) as a function of concentration of interferent, a factorial design was prepared at three levels of each (zero, medium and high concentration), which implies performing 81 determinations. However, a D-optimal design with just nine experiments is sufficiently good to estimate the model proposed. The interference of these metals makes it impossible to determine Cr(VI) when they are present in the sample. To avoid prior separation steps, a multivariate regression by partial least squares, PLS, is proposed to calibrate the Cr(VI) in the presence of these analytes varying the concentration of the Cr(VI) between 0.1 and 0.9mugml(-1) and that of the interferents between 3 and 5mugml(-1). The average errors obtained were 4.5% and 3.29% fitted and in prediction, respectively, with a standard error in prediction (RMSEP) of 0.016% presenting absence of both constant and proportional bias. The detection limit with the PLS regression in the presence of interferents is 0.1mugml(-1) with a probability of false positive equal to 5% and less than 5% for false negative. The capability of detection is similar to that obtained with the univariate calibration (absorbance at 543nm) in absence of interferents. With the PLS regression it is possible to discriminate 0.085mugml(-1) of Cr(VI) in a sample with 0.5mugml(-1) of Cr(VI) with probabilities of false compliance and false non-compliance equal to 0.05. For the univariate calibration without interferents, it was established at 0.0971mugml(-1) of Cr(VI) for the same nominal concentration. In relation to interference of V(V), Fe(III) and Mn(VII), the PLS calibration could be an efficient alternative to the separation step for Cr(VI) spectrophotometric determination using 1,5-diphenylcarbazide.","Analysis of interferents by means a D-optimal screening design and calibration using partial least squares regression in the spectrophotometric determination of Cr(VI) Abs: Using a central composite design, the signal of the process for the spectrophotometric determination of hexavalent chromium (lambda=543nm) is maximised and its variability minimised using as complexing agent 1,5-diphenylcarbazide in sufficiently acid medium. To analyse the interference of various analytes (Mo(VI), V(V), Fe(III) and Mn(VII)) on the Cr(VI) as a function of concentration of interferent, a factorial design was prepared at three levels of each (zero, medium and high concentration), which implies performing 81 determinations. However, a D-optimal design with just nine experiments is sufficiently good to estimate the model proposed. The interference of these metals makes it impossible to determine Cr(VI) when they are present in the sample. To avoid prior separation steps, a multivariate regression by partial least squares, PLS, is proposed to calibrate the Cr(VI) in the presence of these analytes varying the concentration of the Cr(VI) between 0.1 and 0.9mugml(-1) and that of the interferents between 3 and 5mugml(-1). The average errors obtained were 4.5% and 3.29% fitted and in prediction, respectively, with a standard error in prediction (RMSEP) of 0.016% presenting absence of both constant and proportional bias. The detection limit with the PLS regression in the presence of interferents is 0.1mugml(-1) with a probability of false positive equal to 5% and less than 5% for false negative. The capability of detection is similar to that obtained with the univariate calibration (absorbance at 543nm) in absence of interferents. With the PLS regression it is possible to discriminate 0.085mugml(-1) of Cr(VI) in a sample with 0.5mugml(-1) of Cr(VI) with probabilities of false compliance and false non-compliance equal to 0.05. For the univariate calibration without interferents, it was established at 0.0971mugml(-1) of Cr(VI) for the same nominal concentration. In relation to interference of V(V), Fe(III) and Mn(VII), the PLS calibration could be an efficient alternative to the separation step for Cr(VI) spectrophotometric determination using 1,5-diphenylcarbazide."
1509773,Li et al. 2008,"Selective, peroxidase substrate based &quot;signal-on&quot; colorimetric assay for the detection of chromium (VI)","Due to the potentially adverse effects of the chromium (VI) on the human health and also on the environment, the quantitative determination of Cr(VI) is of particular interest. This work herein reports a facile, selective and rapid colorimetric determination of Cr(VI) based on the peroxidase substrate-2,2'-azino-bis(3-ethylbenzo-thiazoline-6-sulfonic acid) diammonium salt (ABTS) as the color developing agent. ABTS, which was usually acted as peroxidase substrate for the enzyme linked immunosorbent assay, is used here for the first time to fabricate the &quot;signal-on&quot; colorimetric Assay for Cr(VI). The ABTS was chosen instead of the commonly used 1,5-diphenylcarbazide (DPC) due to its good solubility, stability, sensitivity and low background. This method provided a convenient colorimetric detection of Cr(VI) with a wider linear range from 8.33 microg L(-1) to 1.25 mg L(-1) by recording the absorption spectra at the wavelength of 419 nm and a low detection limit of 7.87 microg L(-1). In addition, the entire detection takes less than 10 min.","Selective, peroxidase substrate based &quot;signal-on&quot; colorimetric assay for the detection of chromium (VI) Abs: Due to the potentially adverse effects of the chromium (VI) on the human health and also on the environment, the quantitative determination of Cr(VI) is of particular interest. This work herein reports a facile, selective and rapid colorimetric determination of Cr(VI) based on the peroxidase substrate-2,2'-azino-bis(3-ethylbenzo-thiazoline-6-sulfonic acid) diammonium salt (ABTS) as the color developing agent. ABTS, which was usually acted as peroxidase substrate for the enzyme linked immunosorbent assay, is used here for the first time to fabricate the &quot;signal-on&quot; colorimetric Assay for Cr(VI). The ABTS was chosen instead of the commonly used 1,5-diphenylcarbazide (DPC) due to its good solubility, stability, sensitivity and low background. This method provided a convenient colorimetric detection of Cr(VI) with a wider linear range from 8.33 microg L(-1) to 1.25 mg L(-1) by recording the absorption spectra at the wavelength of 419 nm and a low detection limit of 7.87 microg L(-1). In addition, the entire detection takes less than 10 min."
1509772,Rodman et al. 2006,Conversion of chromium(III) propionate to chromium(VI) by the Advanced Oxidation Process Pretreatment of a biomimetic complex for metal analysis,"The use of H(2)O(2) and UV irradiation to remove organic ligands in a chromium(III) complex for the subsequent chromium analysis is reported. The Advanced Oxidation Process (AOP) using a 5.5-W UV lamp, H(2)O(2) and Fe(2+)/Fe(3+) as catalyst (photo Fenton process) was found to give complete and quantitative Cr(III)--&gt;Cr(VI) conversion and removal of ligands in chromium(III) propionate [Cr(3)O(O(2)CCH(2)CH(3))(6)(H(2)O)(3)]NO(3), a biomimetic chromium species, as subsequent chromium analyses by the 1,5-diphenylcarbazide method and atomic absorption revealed. The current process eliminates the need for mineralization and/or dissolution of the matrix in order to remove the organic ligand, the traditional pretreatments of a sample for metal analysis. Studies to optimize the conditions for the oxidation processes, including the use of Fe(2+)/Fe(3+) catalyst, length of UV irradiation, H(2)O(2) concentration, pH, power of UV lamp, and reactor size, are reported.","Conversion of chromium(III) propionate to chromium(VI) by the Advanced Oxidation Process Pretreatment of a biomimetic complex for metal analysis Abs: The use of H(2)O(2) and UV irradiation to remove organic ligands in a chromium(III) complex for the subsequent chromium analysis is reported. The Advanced Oxidation Process (AOP) using a 5.5-W UV lamp, H(2)O(2) and Fe(2+)/Fe(3+) as catalyst (photo Fenton process) was found to give complete and quantitative Cr(III)--&gt;Cr(VI) conversion and removal of ligands in chromium(III) propionate [Cr(3)O(O(2)CCH(2)CH(3))(6)(H(2)O)(3)]NO(3), a biomimetic chromium species, as subsequent chromium analyses by the 1,5-diphenylcarbazide method and atomic absorption revealed. The current process eliminates the need for mineralization and/or dissolution of the matrix in order to remove the organic ligand, the traditional pretreatments of a sample for metal analysis. Studies to optimize the conditions for the oxidation processes, including the use of Fe(2+)/Fe(3+) catalyst, length of UV irradiation, H(2)O(2) concentration, pH, power of UV lamp, and reactor size, are reported."
1509771,Cui et al. 2006,A simple and sensitive chromium speciation procedure by hyphenating flow injection on-line preconcentration with catalytic spectrophotometry,"A high sensitive chromium speciation procedure based on spectrophotometric detection was developed by coupling flow injection on-line preconcentration with a catalytic indicator reaction. Chromium(VI) is retained on a mini-column packed with polystyrene anion exchange resin (strong basic 717 resin), which was afterwards eluted with a small volume of NaNO(3) solution. The eluted Cr(VI) is then directed to catalyze the decoloration of alizarin cyanine green (ACG) in the presence of bromate as oxidizing reagent, and the absorbance change is proportional to the concentration of Cr(VI). With a sampling volume of 12ml and a loading time of 120s, an enrichment factor of 26.5 was achieved for the preconcentration. The most distinct feature of this procedure is characterized by its overall detection limit, i.e., 50ngl(-1), which is much superior to those achieved by FAAS, and comparable to those obtained by inductively coupled plasma mass spectrometry (ICPMS) and electrothermal atomic absorption spectrometry (ETAAS). The procedure was validated with a certified reference material. It was also applied to the speciation of chromium in a series of surface water samples.","A simple and sensitive chromium speciation procedure by hyphenating flow injection on-line preconcentration with catalytic spectrophotometry Abs: A high sensitive chromium speciation procedure based on spectrophotometric detection was developed by coupling flow injection on-line preconcentration with a catalytic indicator reaction. Chromium(VI) is retained on a mini-column packed with polystyrene anion exchange resin (strong basic 717 resin), which was afterwards eluted with a small volume of NaNO(3) solution. The eluted Cr(VI) is then directed to catalyze the decoloration of alizarin cyanine green (ACG) in the presence of bromate as oxidizing reagent, and the absorbance change is proportional to the concentration of Cr(VI). With a sampling volume of 12ml and a loading time of 120s, an enrichment factor of 26.5 was achieved for the preconcentration. The most distinct feature of this procedure is characterized by its overall detection limit, i.e., 50ngl(-1), which is much superior to those achieved by FAAS, and comparable to those obtained by inductively coupled plasma mass spectrometry (ICPMS) and electrothermal atomic absorption spectrometry (ETAAS). The procedure was validated with a certified reference material. It was also applied to the speciation of chromium in a series of surface water samples."
1509770,Themelis et al. 2006,Flow injection direct spectrophotometric assay for the speciation of trace chromium(III) and chromium(VI) using chromotropic acid as chromogenic reagent,"A new rapid and sensitive FI assay is reported for the simultaneous direct spectrophotometric determination of trace Cr(VI) and Cr(III) in real samples. The method is based upon the reaction of Cr(VI) with chromotropic acid (CA) in highly acidic medium to form a water-soluble complex (lambda(max)=370nm). Cr(III) reacts with CA only after its on-line oxidation to Cr(VI) by alkaline KIO(4). The determination of each chromium species in the sample was achieved by absorbance differences. The calibration curves were linear over the range 3-4000mugl(-1) and 30-1200mugl(-1) for Cr(VI) and Cr(III), respectively, while the precision close to the quantitation limit was satisfactory in both cases (s(r)=3.0% for Cr(VI) and 4.0% for Cr(III) (n=10) at 10 and 50mugl(-1) level, respectively). The method developed proved to be adequately selective and sensitive (c(L)=1 and 10mugl(-1) for Cr(VI) and Cr(III), respectively). The application of the method to the analysis of water samples (tap and mineral water) gave accurate results based on recovery studies (93-106%). Analytical results of real sample analysis were in good agreement with certified values.","Flow injection direct spectrophotometric assay for the speciation of trace chromium(III) and chromium(VI) using chromotropic acid as chromogenic reagent Abs: A new rapid and sensitive FI assay is reported for the simultaneous direct spectrophotometric determination of trace Cr(VI) and Cr(III) in real samples. The method is based upon the reaction of Cr(VI) with chromotropic acid (CA) in highly acidic medium to form a water-soluble complex (lambda(max)=370nm). Cr(III) reacts with CA only after its on-line oxidation to Cr(VI) by alkaline KIO(4). The determination of each chromium species in the sample was achieved by absorbance differences. The calibration curves were linear over the range 3-4000mugl(-1) and 30-1200mugl(-1) for Cr(VI) and Cr(III), respectively, while the precision close to the quantitation limit was satisfactory in both cases (s(r)=3.0% for Cr(VI) and 4.0% for Cr(III) (n=10) at 10 and 50mugl(-1) level, respectively). The method developed proved to be adequately selective and sensitive (c(L)=1 and 10mugl(-1) for Cr(VI) and Cr(III), respectively). The application of the method to the analysis of water samples (tap and mineral water) gave accurate results based on recovery studies (93-106%). Analytical results of real sample analysis were in good agreement with certified values."
1509768,Lin et al. 2005,Catalytic adsorptive stripping determination of trace chromium (VI) at the bismuth film electrode,"A sensitive adsorptive stripping voltammetric protocol at a bismuth-coated glassy-carbon electrode for trace measurements of chromium (VI) in the presence of diethylenetriammine pentaacetic acid (DTPA) is described. The new protocol is based on accumulation of the Cr-DTPA complex at a preplated bismuth film electrode held at -0.80V, followed by a negatively-going square-wave voltammetric waveform. Factors influencing the stripping performance including the film preparation, solution pH, DTPA and nitrate concentrations, deposition potential and deposition time, have been optimized. The resulting performance compares well with that observed for analogous measurements at mercury film electrodes. A preconcentration time of 7min results in a detection limit of 0.3nM Cr(VI) and after 2min a relative standard deviation at 20nM of 5.1% (n = 25). Applicability to river water samples is demonstrated. The attractive behavior of the new &quot;mercury-free&quot; chromium sensor holds great promise for on-site environmental and industrial monitoring of chromium (VI). Preliminary data in this direction using bismuth-coated screen-printed electrodes are encouraging.","Catalytic adsorptive stripping determination of trace chromium (VI) at the bismuth film electrode Abs: A sensitive adsorptive stripping voltammetric protocol at a bismuth-coated glassy-carbon electrode for trace measurements of chromium (VI) in the presence of diethylenetriammine pentaacetic acid (DTPA) is described. The new protocol is based on accumulation of the Cr-DTPA complex at a preplated bismuth film electrode held at -0.80V, followed by a negatively-going square-wave voltammetric waveform. Factors influencing the stripping performance including the film preparation, solution pH, DTPA and nitrate concentrations, deposition potential and deposition time, have been optimized. The resulting performance compares well with that observed for analogous measurements at mercury film electrodes. A preconcentration time of 7min results in a detection limit of 0.3nM Cr(VI) and after 2min a relative standard deviation at 20nM of 5.1% (n = 25). Applicability to river water samples is demonstrated. The attractive behavior of the new &quot;mercury-free&quot; chromium sensor holds great promise for on-site environmental and industrial monitoring of chromium (VI). Preliminary data in this direction using bismuth-coated screen-printed electrodes are encouraging."
1509767,Miró and  Frenzel 2004,A critical examination of sorbent extraction pre-concentration with spectrophotometric sensing in flowing systems,"In this paper, the solid-phase spectrophotometric concept is critically examined in flow systems exploiting a dedicated microcolumn-based optical sensor packed with octadecyl chemically-modified silica gel. The flow configuration integrates matrix separation with pre-concentration and on-column sensing of non-polar complexes resulting from analyte derivatization. The design criteria for optimum performance of both the sorbent-packed microcolumn and optosensing instrumentation are for the first time discussed in detail. Practical considerations required to warrant the maximum sorption efficiency of the reversed-phase material by avoiding chain collapse, and avenues to overcome the effects derived from its transparency changes upon solvation with solutions of different polarity are also addressed. The noteworthy features of the flow-through enrichment system involve the sensitivity enhancement with respect to common spectrophotometric procedures in the liquid-phase, as well as the capture of a large amount of scattered light, which is the most severe pitfall of conventional solid-phase absorptiometric approaches using commercially available flow-through cells. Several common spectrophotometric assays for monitoring key inorganic and organic parameters (viz. oxidized nitrogen, ammonium, sulfite, phosphate, iron(II)/total iron, chromium(VI), nickel(II) and phenol index) in environmental samples are taken as practical examples. Plausible sorption mechanisms together with discussions for proper performance of the different investigated reversed-phase extraction optosensing methods are presented in the bulk of the text. Special emphasis is paid to problems arising in real sample analysis due to unspecific sorption of matrix constituents and potential means to circumvent them are thoroughly explored.","A critical examination of sorbent extraction pre-concentration with spectrophotometric sensing in flowing systems Abs: In this paper, the solid-phase spectrophotometric concept is critically examined in flow systems exploiting a dedicated microcolumn-based optical sensor packed with octadecyl chemically-modified silica gel. The flow configuration integrates matrix separation with pre-concentration and on-column sensing of non-polar complexes resulting from analyte derivatization. The design criteria for optimum performance of both the sorbent-packed microcolumn and optosensing instrumentation are for the first time discussed in detail. Practical considerations required to warrant the maximum sorption efficiency of the reversed-phase material by avoiding chain collapse, and avenues to overcome the effects derived from its transparency changes upon solvation with solutions of different polarity are also addressed. The noteworthy features of the flow-through enrichment system involve the sensitivity enhancement with respect to common spectrophotometric procedures in the liquid-phase, as well as the capture of a large amount of scattered light, which is the most severe pitfall of conventional solid-phase absorptiometric approaches using commercially available flow-through cells. Several common spectrophotometric assays for monitoring key inorganic and organic parameters (viz. oxidized nitrogen, ammonium, sulfite, phosphate, iron(II)/total iron, chromium(VI), nickel(II) and phenol index) in environmental samples are taken as practical examples. Plausible sorption mechanisms together with discussions for proper performance of the different investigated reversed-phase extraction optosensing methods are presented in the bulk of the text. Special emphasis is paid to problems arising in real sample analysis due to unspecific sorption of matrix constituents and potential means to circumvent them are thoroughly explored."
1509766,Bobrowski et al. 2004,Chromium speciation study in polluted waters using catalytic adsorptive stripping voltammetry and tangential flow filtration,"The catalytic adsorptive stripping voltammetry (CAdSV) has been applied to physico-chemical chromium speciation study in the upper Dunajec catchment, severely polluted by the tannery wastewater. The method is based on the adsorptive preconcentration of the Cr(III)-diethylenetriammine-N,N,N',N'',N''-pentaacetic acid (DTPA) complex and the utilization of the catalytic reaction in the presence of nitrate. Under optimized conditions the CAdSV enables the oxidation state speciation study of Cr content by direct determination of Cr(VI) in the presence of the predominant Cr(III) concentration with the detection limit for chromium(VI) of 0.08nM and the linearity range from 0.1 to 80nM obtained for 20s of accumulation, as well as the determination of total Cr after UV oxidation of Cr(III) to Cr(VI). Due to the difference in the chemical properties of different chromium species the CAdSV method makes possible a speciation study of Cr(III) and Cr(VI) oxidation state. The RSD of the determination of Cr(VI) and Cr(III) varies from 0.5 to 5%. It has been proved that in natural water in which strong complexants of Cr(III) such a humid acids are presented, Cr(VI) can be determined accurately in the presence of high excess of Cr(III). Fractionation of selected water samples with tangential flow filtration (TFF, cut-off 10 and/or 1kDa) provides insight into physical Cr speciation, i.e. partitioning of the Cr(VI) and Cr(III) between the colloidal and the dissolved fractions. It has been shown that the content of the Cr species in the Dunajec river depends on the season, and is significantly higher in autumn and winter during the most intensive tanneries production processes. The concentration of total Cr exceeds occasionally the legally admissible level. A large fraction of total Cr(III) concentration is associated with the colloidal material, while Cr(VI) occurs solely in the truly dissolved form.","Chromium speciation study in polluted waters using catalytic adsorptive stripping voltammetry and tangential flow filtration Abs: The catalytic adsorptive stripping voltammetry (CAdSV) has been applied to physico-chemical chromium speciation study in the upper Dunajec catchment, severely polluted by the tannery wastewater. The method is based on the adsorptive preconcentration of the Cr(III)-diethylenetriammine-N,N,N',N'',N''-pentaacetic acid (DTPA) complex and the utilization of the catalytic reaction in the presence of nitrate. Under optimized conditions the CAdSV enables the oxidation state speciation study of Cr content by direct determination of Cr(VI) in the presence of the predominant Cr(III) concentration with the detection limit for chromium(VI) of 0.08nM and the linearity range from 0.1 to 80nM obtained for 20s of accumulation, as well as the determination of total Cr after UV oxidation of Cr(III) to Cr(VI). Due to the difference in the chemical properties of different chromium species the CAdSV method makes possible a speciation study of Cr(III) and Cr(VI) oxidation state. The RSD of the determination of Cr(VI) and Cr(III) varies from 0.5 to 5%. It has been proved that in natural water in which strong complexants of Cr(III) such a humid acids are presented, Cr(VI) can be determined accurately in the presence of high excess of Cr(III). Fractionation of selected water samples with tangential flow filtration (TFF, cut-off 10 and/or 1kDa) provides insight into physical Cr speciation, i.e. partitioning of the Cr(VI) and Cr(III) between the colloidal and the dissolved fractions. It has been shown that the content of the Cr species in the Dunajec river depends on the season, and is significantly higher in autumn and winter during the most intensive tanneries production processes. The concentration of total Cr exceeds occasionally the legally admissible level. A large fraction of total Cr(III) concentration is associated with the colloidal material, while Cr(VI) occurs solely in the truly dissolved form."
1509765,Ball and  Mccleskey 2003,A new cation-exchange method for accurate field speciation of hexavalent chromium,"A new method for field speciation of Cr(VI) has been developed to meet present stringent regulatory standards and to overcome the limitations of existing methods. The method consists of passing a water sample through strong acid cation-exchange resin at the field site, where Cr(III) is retained while Cr(VI) passes into the effluent and is preserved for later determination. The method is simple, rapid, portable, and accurate, and makes use of readily available, inexpensive materials. Cr(VI) concentrations are determined later in the laboratory using any elemental analysis instrument sufficiently sensitive to measure the Cr(VI) concentrations of interest. The new method allows measurement of Cr(VI) concentrations as low as 0.05 mug l(-1), storage of samples for at least several weeks prior to analysis, and use of readily available analytical instrumentation. Cr(VI) can be separated from Cr(III) between pH 2 and 11 at Cr(III)/Cr(VI) concentration ratios as high as 1000. The new method has demonstrated excellent comparability with two commonly used methods, the Hach Company direct colorimetric method and USEPA method 218.6. The new method is superior to the Hach direct colorimetric method owing to its relative sensitivity and simplicity. The new method is superior to USEPA method 218.6 in the presence of Fe(II) concentrations up to 1 mg l(-1) and Fe(III) concentrations up to 10 mg l(-1). Time stability of preserved samples is a significant advantage over the 24-h time constraint specified for USEPA method 218.6.","A new cation-exchange method for accurate field speciation of hexavalent chromium Abs: A new method for field speciation of Cr(VI) has been developed to meet present stringent regulatory standards and to overcome the limitations of existing methods. The method consists of passing a water sample through strong acid cation-exchange resin at the field site, where Cr(III) is retained while Cr(VI) passes into the effluent and is preserved for later determination. The method is simple, rapid, portable, and accurate, and makes use of readily available, inexpensive materials. Cr(VI) concentrations are determined later in the laboratory using any elemental analysis instrument sufficiently sensitive to measure the Cr(VI) concentrations of interest. The new method allows measurement of Cr(VI) concentrations as low as 0.05 mug l(-1), storage of samples for at least several weeks prior to analysis, and use of readily available analytical instrumentation. Cr(VI) can be separated from Cr(III) between pH 2 and 11 at Cr(III)/Cr(VI) concentration ratios as high as 1000. The new method has demonstrated excellent comparability with two commonly used methods, the Hach Company direct colorimetric method and USEPA method 218.6. The new method is superior to the Hach direct colorimetric method owing to its relative sensitivity and simplicity. The new method is superior to USEPA method 218.6 in the presence of Fe(II) concentrations up to 1 mg l(-1) and Fe(III) concentrations up to 10 mg l(-1). Time stability of preserved samples is a significant advantage over the 24-h time constraint specified for USEPA method 218.6."
1509764,Revanasiddappa and  Kiran Kumar 2003,A highly sensitive spectrophotometric determination of chromium using leuco Xylene cyanol FF,"A highly sensitive and selective spectrophotometric method was developed for the determination of trace amounts of chromium with leuco Xylene cynaol FF. The method is based on the oxidation of leuco Xylene cyanol FF (LXCFF) to its blue form of Xylene cyanol FF by chromium(VI) in sulphuric acid medium (pH 1.2-2.4), the absorbance of the formed dye is measured in an acetate buffer medium (pH 3.0-4.6) at 615 nm. The method obeys Beer's law in the concentration range of 0.05-0.45 mug ml(-l) chromium, having molar absorptivity and Sandell's sensitivity of 8.23x10(4) l mol(-1) cm(-l) and 0.00063 mug cm(-2), respectively. All the variables were studied in order to optimise the reaction conditions. The developed method has been successfully applied to the determination of chromium in steels, pharmaceutical samples, industrial effluents, natural water, and soil.","A highly sensitive spectrophotometric determination of chromium using leuco Xylene cyanol FF Abs: A highly sensitive and selective spectrophotometric method was developed for the determination of trace amounts of chromium with leuco Xylene cynaol FF. The method is based on the oxidation of leuco Xylene cyanol FF (LXCFF) to its blue form of Xylene cyanol FF by chromium(VI) in sulphuric acid medium (pH 1.2-2.4), the absorbance of the formed dye is measured in an acetate buffer medium (pH 3.0-4.6) at 615 nm. The method obeys Beer's law in the concentration range of 0.05-0.45 mug ml(-l) chromium, having molar absorptivity and Sandell's sensitivity of 8.23x10(4) l mol(-1) cm(-l) and 0.00063 mug cm(-2), respectively. All the variables were studied in order to optimise the reaction conditions. The developed method has been successfully applied to the determination of chromium in steels, pharmaceutical samples, industrial effluents, natural water, and soil."
1509763,Do?utan et al. 2003,Preconcentration and speciation of chromium using a melamine based polymeric sequestering succinic acid resin: its application for Cr(VI) and Cr(III) determination in wastewater,"A new melamine based polymeric sequestering resin was prepared for preconcentration and separation of hexavalent chromium from water, and its sequestering action was investigated. The water-insoluble, cross-linked sequestering resin was formed by reaction with bromosuccinic acid and cross-linking of melamine. The active sequestering group on the resin is NH-(Succinic acid) or salt thereof. The resulting chelating resin was characterized by infrared spectra. The newly prepared resin quantitatively retained Cr(VI) at pH 2.0-4.0 when the flow rate was maintained between 1 and 5 ml min(-1). The retained Cr(VI) was instantaneously eluted with 25 ml of 0.1 M NaOH. The chromium species were determined by a flame atomic absorption spectrometer. The limits of detection for Cr(VI) and Cr(III) were found to be 5.3 and 4.2 microg l(-1), respectively. The precision and accuracy of the proposed procedure was checked by the use synthetic and reference steel samples. The established preconcentration method was successfully applied to the determination and selective separation of Cr(VI) in electroplating industry wastewater. Total concentrations determined by the spectrophotometric method (110.3+/-0.6 g l(-1) Cr(VI) and 1.2+/-0.3 g l(-1) Cr(III)) are compared with those found by FAAS and the obtained results (110.4+/-1.8 g l(-1) Cr(VI) and 1.4+/-0.5 g l(-1) Cr(III)) show good agreement.","Preconcentration and speciation of chromium using a melamine based polymeric sequestering succinic acid resin: its application for Cr(VI) and Cr(III) determination in wastewater Abs: A new melamine based polymeric sequestering resin was prepared for preconcentration and separation of hexavalent chromium from water, and its sequestering action was investigated. The water-insoluble, cross-linked sequestering resin was formed by reaction with bromosuccinic acid and cross-linking of melamine. The active sequestering group on the resin is NH-(Succinic acid) or salt thereof. The resulting chelating resin was characterized by infrared spectra. The newly prepared resin quantitatively retained Cr(VI) at pH 2.0-4.0 when the flow rate was maintained between 1 and 5 ml min(-1). The retained Cr(VI) was instantaneously eluted with 25 ml of 0.1 M NaOH. The chromium species were determined by a flame atomic absorption spectrometer. The limits of detection for Cr(VI) and Cr(III) were found to be 5.3 and 4.2 microg l(-1), respectively. The precision and accuracy of the proposed procedure was checked by the use synthetic and reference steel samples. The established preconcentration method was successfully applied to the determination and selective separation of Cr(VI) in electroplating industry wastewater. Total concentrations determined by the spectrophotometric method (110.3+/-0.6 g l(-1) Cr(VI) and 1.2+/-0.3 g l(-1) Cr(III)) are compared with those found by FAAS and the obtained results (110.4+/-1.8 g l(-1) Cr(VI) and 1.4+/-0.5 g l(-1) Cr(III)) show good agreement."
1509762,Anthemidis et al. 2002,"On-line preconcentration and determination of copper, lead and chromium(VI) using unloaded polyurethane foam packed column by flame atomic absorption spectrometry in natural waters and biological samples","A simple, sensitive and low cost, flow injection time-based method was developed for on-line preconcentration and determination of copper, lead and chromium(VI) at sub mug l(-1) levels in natural waters and biological samples. At the optimum pH, the on-line formed metal-ammonium pyrrolidine dithiocarbamate (APDC) complexes were sorbed on the unloaded commercial polyurethane foam (PUF), and subsequent eluted quantitatively by isobutylmethylketone and determined by flame atomic absorption spectrometry (FAAS). All chemical, and flow injection variables were optimized for the quantitative preconcentration of each metal and a study of interference level of various ions was also carried out. The system offered improved flexibility, low backpressure and applicability to all the studied metals. At a sample frequency of 36 h(-1) and a 60 s preconcentration time, the enhancement factor was 170, 131 and 28, the detection limit was 0.2, 1.8 and 2.0 mug l(-1), and the precision, expressed as relative standard deviation (s(r)), was 2.8 (at 10 mug l(-1)), 3.4 (at 50 mug l(-1)) and 3.6% (at 50 mug l(-1)) for Cu(II), Pb(II) and Cr(VI), respectively. The accuracy of the developed method was sufficient and evaluated by the analysis of certified reference materials and spiked water samples. Finally, the method was applied to the analysis of environmental samples.","On-line preconcentration and determination of copper, lead and chromium(VI) using unloaded polyurethane foam packed column by flame atomic absorption spectrometry in natural waters and biological samples Abs: A simple, sensitive and low cost, flow injection time-based method was developed for on-line preconcentration and determination of copper, lead and chromium(VI) at sub mug l(-1) levels in natural waters and biological samples. At the optimum pH, the on-line formed metal-ammonium pyrrolidine dithiocarbamate (APDC) complexes were sorbed on the unloaded commercial polyurethane foam (PUF), and subsequent eluted quantitatively by isobutylmethylketone and determined by flame atomic absorption spectrometry (FAAS). All chemical, and flow injection variables were optimized for the quantitative preconcentration of each metal and a study of interference level of various ions was also carried out. The system offered improved flexibility, low backpressure and applicability to all the studied metals. At a sample frequency of 36 h(-1) and a 60 s preconcentration time, the enhancement factor was 170, 131 and 28, the detection limit was 0.2, 1.8 and 2.0 mug l(-1), and the precision, expressed as relative standard deviation (s(r)), was 2.8 (at 10 mug l(-1)), 3.4 (at 50 mug l(-1)) and 3.6% (at 50 mug l(-1)) for Cu(II), Pb(II) and Cr(VI), respectively. The accuracy of the developed method was sufficient and evaluated by the analysis of certified reference materials and spiked water samples. Finally, the method was applied to the analysis of environmental samples."
1509761,Li et al. 2002,Selective determination of airborne hexavalent chromium using inductively coupled plasma mass spectrometry,"A new method for determining ultra-trace levels of hexavalent chromium in ambient air has been developed. The method involves a 24-h sampling of air into potassium hydroxide solution, followed by silica gel column separation of chromium (VI), then preconcentration by complexation and solvent extraction. The chromium (VI) complex was dissolved in nitric acid. The resultant chromium ions were determined by inductively coupled plasma mass spectrometry (ICP-MS) using a dynamic reaction cell (DRC) with ammonia as the reactive gas to reduce polyatomic interferences. The interconversion of chromium in potassium hydroxide solution and air sample matrix were investigated under ambient conditions. It was found that there was no conversion of chromium (VI) into chromium (III) species. However, it was observed that some chromium (III) species were converted into chromium (VI) species. For a KOH solution containing 100 mug l(-1) of chromium (III) species, the rate of conversion was found to be 3% after 24 h exposure, 8% after 48 h, 10% after 72 h and no further conversion was observed thereafter. However, in a solution containing air sample matrix, 9.3% of chromium (III) converted to chromium (VI) within 6 h, and during the course of a 11-day exposure period, 13% (range 8-17%) of chromium (III) converted to chromium (VI). The method detection limit (MDL) for chromium (VI) in potassium hydroxide solution (0.025 M) was found to be 2x10(-2) mug l(-1). This is equivalent to 0.2 ng m(-3) (for 23 m(3) air sampled into 200 ml of KOH solution over a 24-h period). The recovery of spiked chromium (VI) from solutions containing air sample matrix was 95+/-9% (n=8). Matrix related interferences were estimated to be less than 10% based on recovery studies. The concentration of airborne chromium (VI) in Sydney residential areas was found to be less than 0.2 ng m(-3), however, in industrial areas the concentrations ranged from 0.2 to 1.3 ng m(-3) using this analytical procedure.","Selective determination of airborne hexavalent chromium using inductively coupled plasma mass spectrometry Abs: A new method for determining ultra-trace levels of hexavalent chromium in ambient air has been developed. The method involves a 24-h sampling of air into potassium hydroxide solution, followed by silica gel column separation of chromium (VI), then preconcentration by complexation and solvent extraction. The chromium (VI) complex was dissolved in nitric acid. The resultant chromium ions were determined by inductively coupled plasma mass spectrometry (ICP-MS) using a dynamic reaction cell (DRC) with ammonia as the reactive gas to reduce polyatomic interferences. The interconversion of chromium in potassium hydroxide solution and air sample matrix were investigated under ambient conditions. It was found that there was no conversion of chromium (VI) into chromium (III) species. However, it was observed that some chromium (III) species were converted into chromium (VI) species. For a KOH solution containing 100 mug l(-1) of chromium (III) species, the rate of conversion was found to be 3% after 24 h exposure, 8% after 48 h, 10% after 72 h and no further conversion was observed thereafter. However, in a solution containing air sample matrix, 9.3% of chromium (III) converted to chromium (VI) within 6 h, and during the course of a 11-day exposure period, 13% (range 8-17%) of chromium (III) converted to chromium (VI). The method detection limit (MDL) for chromium (VI) in potassium hydroxide solution (0.025 M) was found to be 2x10(-2) mug l(-1). This is equivalent to 0.2 ng m(-3) (for 23 m(3) air sampled into 200 ml of KOH solution over a 24-h period). The recovery of spiked chromium (VI) from solutions containing air sample matrix was 95+/-9% (n=8). Matrix related interferences were estimated to be less than 10% based on recovery studies. The concentration of airborne chromium (VI) in Sydney residential areas was found to be less than 0.2 ng m(-3), however, in industrial areas the concentrations ranged from 0.2 to 1.3 ng m(-3) using this analytical procedure."
1509760,Anthemidis et al. 2002,Flame atomic absorption spectrometric determination of chromium(VI) by on-line preconcentration system using a PTFE packed column,"A new, sensitive and robust time-based flow injection (FI) method for on-line preconcentration and determination of ultra trace amounts of chromium(VI) by flame atomic absorption spectrometry (FAAS) has been elaborated. The sample is initially mixed on-line with ammonium pyrrolidine dithiocarbamate (APDC) and the Cr(VI)-PDC chelate is absorbed quantitatively on a mini-column packed with polytetrafluoroethylene (PTFE) turnings at a pH range 0.8-1.4. The complex is subsequently eluted with isobutyl methyl ketone (IBMK) and introduced directly into the nebulizer-burner system. The optimized system offered improved performance characteristics, with unlimited lifetime of the proposed column. The enhancement factor was 80, for a 3-min preconcentration time and the sample frequency was 18 h(-1). The calibration curve was linear over the concentration range 1-40 mug l(-1) with a detection limit of c(L)=0.8 mug l(-1) and a relative standard deviation of s(r)=3.2%, at the 20 mug l(-1) level. The proposed method was evaluated by analyzing samples of certified and spiked water, and it was applied to the analysis of natural water samples and sediments.","Flame atomic absorption spectrometric determination of chromium(VI) by on-line preconcentration system using a PTFE packed column Abs: A new, sensitive and robust time-based flow injection (FI) method for on-line preconcentration and determination of ultra trace amounts of chromium(VI) by flame atomic absorption spectrometry (FAAS) has been elaborated. The sample is initially mixed on-line with ammonium pyrrolidine dithiocarbamate (APDC) and the Cr(VI)-PDC chelate is absorbed quantitatively on a mini-column packed with polytetrafluoroethylene (PTFE) turnings at a pH range 0.8-1.4. The complex is subsequently eluted with isobutyl methyl ketone (IBMK) and introduced directly into the nebulizer-burner system. The optimized system offered improved performance characteristics, with unlimited lifetime of the proposed column. The enhancement factor was 80, for a 3-min preconcentration time and the sample frequency was 18 h(-1). The calibration curve was linear over the concentration range 1-40 mug l(-1) with a detection limit of c(L)=0.8 mug l(-1) and a relative standard deviation of s(r)=3.2%, at the 20 mug l(-1) level. The proposed method was evaluated by analyzing samples of certified and spiked water, and it was applied to the analysis of natural water samples and sediments."
1509759,Yang et al. 2001,Determination of chromium(VI) and lead(II) in drinking water by electrokinetic flow analysis system and graphite furnace atomic absorption spectrometry,"An electrokinetic flow analysis system (EKFA) using an electroosmotic pump (Peo) and a bi-directional electrostacking (BDES) unit is introduced in this paper. Large flow range, moderate carrier pressure, low performance voltage and stable flow rate, especially in mulmin(-1) level, are the main specialties of the Peo. Diethanolamine, 0.5 mM, is selected as its carrier to improve the pump efficiency and stability further. Moreover, BDES, a feasibility investigation for the simultaneous separation and pre-concentration of cations and anions, and graphite furnace atomic absorption spectrometry (GFAAS) determination are presented. The calibration series for both of Cr(VI) and Pb(II) are from 0.2 to 40 mugl(-1) with 10 mul pipette volume and GFAAS determination directly. The detection limit of Cr(VI) and Pb(II) with 10 min BDES is 10 and 13 ngl(-1)(3sigma of blank, n=11), respectively. The recovery of Cr(VI) and Pb(II) is (103-105)+/-1% and (95.9-96.9)+/-1.0% with three independent determinations, respectively. The investigated method is also suitable for the simultaneous separation and pre-concentration of trace cations and anions in low conductivity sample solutions with different detection instruments.","Determination of chromium(VI) and lead(II) in drinking water by electrokinetic flow analysis system and graphite furnace atomic absorption spectrometry Abs: An electrokinetic flow analysis system (EKFA) using an electroosmotic pump (Peo) and a bi-directional electrostacking (BDES) unit is introduced in this paper. Large flow range, moderate carrier pressure, low performance voltage and stable flow rate, especially in mulmin(-1) level, are the main specialties of the Peo. Diethanolamine, 0.5 mM, is selected as its carrier to improve the pump efficiency and stability further. Moreover, BDES, a feasibility investigation for the simultaneous separation and pre-concentration of cations and anions, and graphite furnace atomic absorption spectrometry (GFAAS) determination are presented. The calibration series for both of Cr(VI) and Pb(II) are from 0.2 to 40 mugl(-1) with 10 mul pipette volume and GFAAS determination directly. The detection limit of Cr(VI) and Pb(II) with 10 min BDES is 10 and 13 ngl(-1)(3sigma of blank, n=11), respectively. The recovery of Cr(VI) and Pb(II) is (103-105)+/-1% and (95.9-96.9)+/-1.0% with three independent determinations, respectively. The investigated method is also suitable for the simultaneous separation and pre-concentration of trace cations and anions in low conductivity sample solutions with different detection instruments."
1509758,Balogh et al. 2000,Spectrophotometric study of the complexation and extraction of chromium(VI) with cyanine dyes,"Solvent extraction of chromium(VI) ion associates with symmetric cyanine dyes including the heterocyclic radicals of 1,3,3-trimethyl-3N-indoline, benzooxazol, benzothiazol and quinoline has been studied by means of spectrophotometric method. In the acidic medium in the presence of chloride ions, extractable by aromatic hydrocarbons and esters of acetic acids, chromium(VI) ion associates are formed. The molar absorptivities of ion associates are 2.5-3.6x10(5) l mol(-1) cm(-1) in dependence on extractant and dye. The absorbance of the coloured extracts obeys the Beer's law in the range 0.01-2.1 mg l(-1). The extraction of chromium is the highest during extraction from the sulphuric acid medium in the range 0.05-03 M H(2)SO(4). It was found that the Cr(VI):Cl:R molar ratio is 1:1:1. A novel procedure of chromium(VI) extraction and spectrophotometric determination in various types of soils and sewage doped with chromium(VI) was examined.","Spectrophotometric study of the complexation and extraction of chromium(VI) with cyanine dyes Abs: Solvent extraction of chromium(VI) ion associates with symmetric cyanine dyes including the heterocyclic radicals of 1,3,3-trimethyl-3N-indoline, benzooxazol, benzothiazol and quinoline has been studied by means of spectrophotometric method. In the acidic medium in the presence of chloride ions, extractable by aromatic hydrocarbons and esters of acetic acids, chromium(VI) ion associates are formed. The molar absorptivities of ion associates are 2.5-3.6x10(5) l mol(-1) cm(-1) in dependence on extractant and dye. The absorbance of the coloured extracts obeys the Beer's law in the range 0.01-2.1 mg l(-1). The extraction of chromium is the highest during extraction from the sulphuric acid medium in the range 0.05-03 M H(2)SO(4). It was found that the Cr(VI):Cl:R molar ratio is 1:1:1. A novel procedure of chromium(VI) extraction and spectrophotometric determination in various types of soils and sewage doped with chromium(VI) was examined."
1509757,Gan et al. 2000,Mechanism of porous core electroosmotic pump flow injection system and its application to determination of chromium(VI) in waste-water,"An electroosmotic pump flow injection system is introduced in this paper. According to electroosmotic theory, the pump's properties were described. A large flow range (mul min(-1)-ml min(-1)), moderate carrier pressure (&gt;0.15 MPa), reduced performance voltage (&lt;500 V) and stable flow rate (RSD&lt;3.0% in 4 h) are the main properties of the pump. NH(4)OH (0.35 mM) was used as carrier for improving the pump's flow stability. The electroosmotic efficiency of the pump's medium, porous core, can be recovered and regenerated. A sandwich zone was used for sample and reagent introduction in order to adapt to the pump performance. Flow injection-spectrophotometry was employed for the determination of Cr(VI) in waste-water, based on the formation of the complex with 1,5-diphenylcarbazide and absorbance measurement at 540 nm. Within the calibration range of 0-7.0 mg l(-1) of Cr(VI), the RSD was 0.4% (n=5). The recovery of 0.70 mg l(-1) Cr(VI) added to the waste-water sample was 94.5+/-2.0% (n=5).","Mechanism of porous core electroosmotic pump flow injection system and its application to determination of chromium(VI) in waste-water Abs: An electroosmotic pump flow injection system is introduced in this paper. According to electroosmotic theory, the pump's properties were described. A large flow range (mul min(-1)-ml min(-1)), moderate carrier pressure (&gt;0.15 MPa), reduced performance voltage (&lt;500 V) and stable flow rate (RSD&lt;3.0% in 4 h) are the main properties of the pump. NH(4)OH (0.35 mM) was used as carrier for improving the pump's flow stability. The electroosmotic efficiency of the pump's medium, porous core, can be recovered and regenerated. A sandwich zone was used for sample and reagent introduction in order to adapt to the pump performance. Flow injection-spectrophotometry was employed for the determination of Cr(VI) in waste-water, based on the formation of the complex with 1,5-diphenylcarbazide and absorbance measurement at 540 nm. Within the calibration range of 0-7.0 mg l(-1) of Cr(VI), the RSD was 0.4% (n=5). The recovery of 0.70 mg l(-1) Cr(VI) added to the waste-water sample was 94.5+/-2.0% (n=5)."
1509756,Zhang et al. 1999,"Colour reaction of chromium (VI) with N,N-diethyl-1,4-phenylenediame in the presence of ethanol and cyclohexyldiamine tetraacetic acid as well as its application in the species analysis of chromium","A simple, rapid and precise spectrophotometric method for the determination of Chromium (III and IV) has been developed. The reaction of Cr(VI) with N,N-diethyl-1,4-phenylenediamine is almost complete in a twinkling, which yields a red product with a wavelength of maximum absorption at 530 nm. Beer's Law is obeyed in the Cr concentration range of 0-2.0 mug ml(-1). The molar absorptivity is 5.0x10(4) l mol(-1) cm(-1), limit of detection 0.002 mug ml(-1) and relative SD=1.13% for 5.04 mug Cr. The colouring rate and absorbance are not noticeably affected by temperature from 2 to 45 degrees C. The amounts of Cr(VI) and Cr(III) were measured by determining Cr(VI) first under the condition of masking Cr(III) by cyclohexyldiamine tetraacetic acid, and then the total amount by oxidation of Cr(III). The method was applied to the analyses of some industrial waste waters containing Cr with satisfactory results.","Colour reaction of chromium (VI) with N,N-diethyl-1,4-phenylenediame in the presence of ethanol and cyclohexyldiamine tetraacetic acid as well as its application in the species analysis of chromium Abs: A simple, rapid and precise spectrophotometric method for the determination of Chromium (III and IV) has been developed. The reaction of Cr(VI) with N,N-diethyl-1,4-phenylenediamine is almost complete in a twinkling, which yields a red product with a wavelength of maximum absorption at 530 nm. Beer's Law is obeyed in the Cr concentration range of 0-2.0 mug ml(-1). The molar absorptivity is 5.0x10(4) l mol(-1) cm(-1), limit of detection 0.002 mug ml(-1) and relative SD=1.13% for 5.04 mug Cr. The colouring rate and absorbance are not noticeably affected by temperature from 2 to 45 degrees C. The amounts of Cr(VI) and Cr(III) were measured by determining Cr(VI) first under the condition of masking Cr(III) by cyclohexyldiamine tetraacetic acid, and then the total amount by oxidation of Cr(III). The method was applied to the analyses of some industrial waste waters containing Cr with satisfactory results."
1509755,Yao and  Byrne 1999,Determination of trace chromium(VI) and molybdenum(VI) in natural and bottled mineral waters using long pathlength absorbance spectroscopy (LPAS),"A liquid core waveguide (LCW) has been used to extend the sensitivity of conventional absorbance spectroscopy for chromium(VI) and molybdenum(VI). Analysis of Cr(VI) and Mo(VI) concentrations in water samples with a 5.0 m pathlength LCW made of Teflon AF-2400 provides 0.2 and 0.6 nM detection limits, respectively. No preconcentration is required in this analysis. The proposed procedures were applied to the determination of chromium(VI) and molybdenum(VI) in natural waters and commercial drinking water. The analytical apparatus is very simple and robust and is amenable to miniaturization and autonomous operation.","Determination of trace chromium(VI) and molybdenum(VI) in natural and bottled mineral waters using long pathlength absorbance spectroscopy (LPAS) Abs: A liquid core waveguide (LCW) has been used to extend the sensitivity of conventional absorbance spectroscopy for chromium(VI) and molybdenum(VI). Analysis of Cr(VI) and Mo(VI) concentrations in water samples with a 5.0 m pathlength LCW made of Teflon AF-2400 provides 0.2 and 0.6 nM detection limits, respectively. No preconcentration is required in this analysis. The proposed procedures were applied to the determination of chromium(VI) and molybdenum(VI) in natural waters and commercial drinking water. The analytical apparatus is very simple and robust and is amenable to miniaturization and autonomous operation."
1509754,Chappell et al. 1998,Quantitative analysis of chromium(V) by EPR spectroscopy,"A procedure to accurately quantitate chromium(V) in environmental and medicinal chemistry samples was developed using electron paramagnetic resonance spectroscopy (EPRS) as the method of detection. It was found to have an error in the order of +/-10% and a detection limit of 0.010 mM (0.5 mg l(-1)) chromium(V). The method has been used to quantitate the formation of chromium(V) in the interaction of chromium(VI) with fulvic acid and a simple model of this acid, viz, 1.2-dihydroxybenzene. Analysis of solutions obtained from the reaction of 1,2-dihydroxybenzene with chromium(VI) demonstrated that even when the organic substrate was present in a 182-fold excess, the maximum chromium(V) concentration attained represented just 1.44% of the initial chromium(VI). Reactions between chromium(VI) and fulvic acid yielded similar results. It was therefore concluded that at background environmental concentrations of chromium and fulvic acid, the production of chromium(V) is insignificant, however, its possible importance in contaminated systems cannot be disregarded on this basis alone. The method for quantitative analysis reported in this paper should be an invaluable tool for investigations into the significance of chromium(V) in the toxicological mechanism of chromium(VI) and its role as a mutagenic agent.","Quantitative analysis of chromium(V) by EPR spectroscopy Abs: A procedure to accurately quantitate chromium(V) in environmental and medicinal chemistry samples was developed using electron paramagnetic resonance spectroscopy (EPRS) as the method of detection. It was found to have an error in the order of +/-10% and a detection limit of 0.010 mM (0.5 mg l(-1)) chromium(V). The method has been used to quantitate the formation of chromium(V) in the interaction of chromium(VI) with fulvic acid and a simple model of this acid, viz, 1.2-dihydroxybenzene. Analysis of solutions obtained from the reaction of 1,2-dihydroxybenzene with chromium(VI) demonstrated that even when the organic substrate was present in a 182-fold excess, the maximum chromium(V) concentration attained represented just 1.44% of the initial chromium(VI). Reactions between chromium(VI) and fulvic acid yielded similar results. It was therefore concluded that at background environmental concentrations of chromium and fulvic acid, the production of chromium(V) is insignificant, however, its possible importance in contaminated systems cannot be disregarded on this basis alone. The method for quantitative analysis reported in this paper should be an invaluable tool for investigations into the significance of chromium(V) in the toxicological mechanism of chromium(VI) and its role as a mutagenic agent."
1509753,Devaragudi and  Hussain Reddy 1997,"Analytical properties of 5,5-dimetyl 1,3-cyclohexanedione dithiosemicarbazone monohydrochloride; spectrophotometric determination of chromium(VI) in alloy steels and industrial effluents","The analytical properties of 5,5-dimethyl 1,3-cyclohexanedione dithiosemicarbazone monohydrochloride (5,5-DiMe-1,3-CHDT.HCl) are described. The reagent gives pink coloured solutions with chromium(VI) in acetic medium. The maximum colour intensity is observed in 0.5-2.5 pH range. This colour reaction (molar absorptivity, 1.63 x 10(4) 1 mol(-1) cm(-1) at 360 nm) has been used for the spectrophotometric determination of total chromium in alloy steels and industrial effluents.","Analytical properties of 5,5-dimetyl 1,3-cyclohexanedione dithiosemicarbazone monohydrochloride; spectrophotometric determination of chromium(VI) in alloy steels and industrial effluents Abs: The analytical properties of 5,5-dimethyl 1,3-cyclohexanedione dithiosemicarbazone monohydrochloride (5,5-DiMe-1,3-CHDT.HCl) are described. The reagent gives pink coloured solutions with chromium(VI) in acetic medium. The maximum colour intensity is observed in 0.5-2.5 pH range. This colour reaction (molar absorptivity, 1.63 x 10(4) 1 mol(-1) cm(-1) at 360 nm) has been used for the spectrophotometric determination of total chromium in alloy steels and industrial effluents."
1509752,Luo et al. 1997,Sequential injection wetting film extraction applied to the spectrophotometric determination of chromium(VI) and chromium(III) in water,"The spectrophotometric determination of Cr(VI) and Cr(III) via sequential injection was used to demonstrate the sensitivity enhancement provided by a newly developed wetting film extraction system. The reaction product of Cr(VI) with 1,5-diphenylcarbazide was ion-paired with perchlorate and extracted into an organic wetting film consisting of octanol and 4-methyl-2-pentanone on the inner wall of a Teflon tube. The wetting film, with the extracted analyte, was then eluted with 100 mul acetonitrile and the analyte determined spectrophotometrically at 546 nm. Important optimized parameters were the selection of wetting film and elution solvents, the flow rate, the length and diameter of the extraction coil and the conditions for the formation of the ion paired chelate. Cr(III) was previously oxidized to Cr(VI) and calculated as the difference between total Cr and Cr(VI). An enrichment factor of 25 and a detection limit of 2.0 mug l(-1) Cr(VI) were achieved with a sampling frequency of 17 h(-1). The calibration curve was linear up to 100 mug l(-1) Cr(VI) (r = 0.999). The relative standard deviations were 2.8 and 2.0% at the 25 and 100 mug l(-1) levels.","Sequential injection wetting film extraction applied to the spectrophotometric determination of chromium(VI) and chromium(III) in water Abs: The spectrophotometric determination of Cr(VI) and Cr(III) via sequential injection was used to demonstrate the sensitivity enhancement provided by a newly developed wetting film extraction system. The reaction product of Cr(VI) with 1,5-diphenylcarbazide was ion-paired with perchlorate and extracted into an organic wetting film consisting of octanol and 4-methyl-2-pentanone on the inner wall of a Teflon tube. The wetting film, with the extracted analyte, was then eluted with 100 mul acetonitrile and the analyte determined spectrophotometrically at 546 nm. Important optimized parameters were the selection of wetting film and elution solvents, the flow rate, the length and diameter of the extraction coil and the conditions for the formation of the ion paired chelate. Cr(III) was previously oxidized to Cr(VI) and calculated as the difference between total Cr and Cr(VI). An enrichment factor of 25 and a detection limit of 2.0 mug l(-1) Cr(VI) were achieved with a sampling frequency of 17 h(-1). The calibration curve was linear up to 100 mug l(-1) Cr(VI) (r = 0.999). The relative standard deviations were 2.8 and 2.0% at the 25 and 100 mug l(-1) levels."
1509751,Girard and  Hubert 1996,Speciation of chromium (VI) and total chromium determination in welding dust samples by flow-injection analysis coupled to atomic absorption spectrometry,"We have studied the speciation of chromium (VI) in stainless-steel welding dusts. The approach used for the analysis of Cr(VI) and total Cr relies on a flow-injection analyzer (FIA) equipped with two different sequential detectors. The system measures Cr(VI). by colorimetry (with 1,5-diphenyl carbohydrazide) and total chromium content by flame atomic absorption spectroscopy (AAS). The extraction of the samples of welding-fume dusts is achieved in a buffer solution (acetic acid and sodium acetate at pH 4). This extraction procedure gives a 96% recovery of chromium (VI). The FIA-AAS system that has been described is also more sensitive, has a lower detection limit (0.005 mug ml(-1)) and gives a better precision (&lt; 1%) than other equivalent systems that have been previously described.","Speciation of chromium (VI) and total chromium determination in welding dust samples by flow-injection analysis coupled to atomic absorption spectrometry Abs: We have studied the speciation of chromium (VI) in stainless-steel welding dusts. The approach used for the analysis of Cr(VI) and total Cr relies on a flow-injection analyzer (FIA) equipped with two different sequential detectors. The system measures Cr(VI). by colorimetry (with 1,5-diphenyl carbohydrazide) and total chromium content by flame atomic absorption spectroscopy (AAS). The extraction of the samples of welding-fume dusts is achieved in a buffer solution (acetic acid and sodium acetate at pH 4). This extraction procedure gives a 96% recovery of chromium (VI). The FIA-AAS system that has been described is also more sensitive, has a lower detection limit (0.005 mug ml(-1)) and gives a better precision (&lt; 1%) than other equivalent systems that have been previously described."
1509750,Kamburova 1993,Iodnitrotetrazolium chloride-A new analytical reagent for determination of chromium,"The extraction of chromium (VI) with iodnitrotetrazolium chloride (INT) was studied spectrophotometrically. The basic spectrophotometric characteristics of the ion associated formed were determined. Using different methods it was found that the ratio between chromium and INT was 1:1. The molar absorptivity of the associate is (250) = (3.70 +/- 0.08) x 10(4) 1.mole(-1).cm(-1). Performing the reaction in acid medium (0.1-1.1M hydrochloric acid) allowed the determination of chromium in the presence of large amounts of W(VI), Mo(VI), Fe(III) and V(V). Hence INT is suggested as a sensitive and selective reagent for extractive-spectrophotometric determination of microquantities of chromium(VI).","Iodnitrotetrazolium chloride-A new analytical reagent for determination of chromium Abs: The extraction of chromium (VI) with iodnitrotetrazolium chloride (INT) was studied spectrophotometrically. The basic spectrophotometric characteristics of the ion associated formed were determined. Using different methods it was found that the ratio between chromium and INT was 1:1. The molar absorptivity of the associate is (250) = (3.70 +/- 0.08) x 10(4) 1.mole(-1).cm(-1). Performing the reaction in acid medium (0.1-1.1M hydrochloric acid) allowed the determination of chromium in the presence of large amounts of W(VI), Mo(VI), Fe(III) and V(V). Hence INT is suggested as a sensitive and selective reagent for extractive-spectrophotometric determination of microquantities of chromium(VI)."
1509749,Shaopu and  Fuchang 1991,A highly sensitive colour reaction for chromium(VI) with the iodide-basic xanthene dye-pva system,"A highly sensitive spectrophotometric method has been developed for determination of chromium(VI), based on oxidation of I(-) to I(-)(3) in acid medium, then formation of a 1:1 ion-association compound of I(-)(3) with a basic xanthene dye in the presence of poly(vinyl alcohol). The molar absorptivity is 1.79 x 10(5) 1.mole(-1).cm(-1) at 600 nm for the Rhodamine B system, 1.56 x 10(5) 1.mole(-1).cm(-1) at 600 nm with Ethylrhodamine B, 1.56 x 10(5) 1.mole(-).cm(-1) at 570 nm with Rhodamine 6G and 2.01 x 10(5) 1.mole(-1).cm(-1) at 590 nm with Butylrhodamine B, respectively. Preconcentration of chromium(VI) by an improved trioctylamine extraction procedure greatly increases the selectivity of the method and can be applied in the spectrophotometric determination of trace amounts of chromium(VI) in tap water, hot-spring water and river water.","A highly sensitive colour reaction for chromium(VI) with the iodide-basic xanthene dye-pva system Abs: A highly sensitive spectrophotometric method has been developed for determination of chromium(VI), based on oxidation of I(-) to I(-)(3) in acid medium, then formation of a 1:1 ion-association compound of I(-)(3) with a basic xanthene dye in the presence of poly(vinyl alcohol). The molar absorptivity is 1.79 x 10(5) 1.mole(-1).cm(-1) at 600 nm for the Rhodamine B system, 1.56 x 10(5) 1.mole(-1).cm(-1) at 600 nm with Ethylrhodamine B, 1.56 x 10(5) 1.mole(-).cm(-1) at 570 nm with Rhodamine 6G and 2.01 x 10(5) 1.mole(-1).cm(-1) at 590 nm with Butylrhodamine B, respectively. Preconcentration of chromium(VI) by an improved trioctylamine extraction procedure greatly increases the selectivity of the method and can be applied in the spectrophotometric determination of trace amounts of chromium(VI) in tap water, hot-spring water and river water."
1509748,Donaldson 1988,"Determination of selenium in ores, concentrates and related materials by graphite-furnace atomic-absorption spectrometry after separation by extraction of the 4-nitro-o-phenylenediamine complex","A method for determining approximately 0.01 mug/g or more of selenium in ores, concentrates, rocks, soils, sediments and related materials is described. After sample decomposition selenium is reduced to selenium(IV) by heating in 4M hydrochloric acid and separated from the matrix elements by toluene extraction of its 5-nitropiazselenol complex from approximately 4.2M hydrochloric acid. After the extract has been washed with 2% nitric acid to remove residual iron, copper and chloride, the selenium in the extract is oxidized to selenium(VI) with 20% bromine solution in cyclohexane and stripped into water. This solution is evaporated to dryness in the presence of nickel, and selenium is ultimately determined in a 2% v/v nitric acid medium by graphite-furnace atomic-absorption spectrometry at 196.0 nm with the nickel functioning as matrix modifier. Common ions, including large amounts of iron, copper and lead, do not interfere. More than 1 mg of vanadium(V) and 0.25 mg each of platinum(IV), palladium(II), and gold(III) causes high results for selenium, and more than 1 mg of tungsten(VI) and 2 mg of molybdenum(VI) causes low results. Interference from chromium(VI) is eliminated by reducing it to chromium(III) with hydroxylamine hydrochloride before the formation of the selenium complex.","Determination of selenium in ores, concentrates and related materials by graphite-furnace atomic-absorption spectrometry after separation by extraction of the 4-nitro-o-phenylenediamine complex Abs: A method for determining approximately 0.01 mug/g or more of selenium in ores, concentrates, rocks, soils, sediments and related materials is described. After sample decomposition selenium is reduced to selenium(IV) by heating in 4M hydrochloric acid and separated from the matrix elements by toluene extraction of its 5-nitropiazselenol complex from approximately 4.2M hydrochloric acid. After the extract has been washed with 2% nitric acid to remove residual iron, copper and chloride, the selenium in the extract is oxidized to selenium(VI) with 20% bromine solution in cyclohexane and stripped into water. This solution is evaporated to dryness in the presence of nickel, and selenium is ultimately determined in a 2% v/v nitric acid medium by graphite-furnace atomic-absorption spectrometry at 196.0 nm with the nickel functioning as matrix modifier. Common ions, including large amounts of iron, copper and lead, do not interfere. More than 1 mg of vanadium(V) and 0.25 mg each of platinum(IV), palladium(II), and gold(III) causes high results for selenium, and more than 1 mg of tungsten(VI) and 2 mg of molybdenum(VI) causes low results. Interference from chromium(VI) is eliminated by reducing it to chromium(III) with hydroxylamine hydrochloride before the formation of the selenium complex."
1509747,Shen-Yang and  Ke-An 1986,The distribution of chromium(VI) species in solution as a function of pH and concentration,"The distribution of the chromium(VI) species CrO(2-)(4), Cr(2)O(2-)(7), HCrO(-)(4), and H(2)CrO(4) in aqueous solutions with total chromium(VI) concentrations of 10(-2)-10(-6)M at pH 1-8 have been calculated.","The distribution of chromium(VI) species in solution as a function of pH and concentration Abs: The distribution of the chromium(VI) species CrO(2-)(4), Cr(2)O(2-)(7), HCrO(-)(4), and H(2)CrO(4) in aqueous solutions with total chromium(VI) concentrations of 10(-2)-10(-6)M at pH 1-8 have been calculated."
1509746,Ohashi et al. 1984,Solvent extraction of the ion-pairs of chromium(VI) and molybdenum(VI) with trioctylmethylammonium chloride and benzyldimethylcetylammonium chloride,"The number of capriquat molecules per chromium(VI) atom in the chromate-capriquat ion-association complex has been found to be between one and two. The distribution ratio in the extraction of chromium(VI) with capriquat is dependent on the dielectric constant of the organic solvent, with a minimum at a dielectric constant of about 8. The absorption spectra of the ion-pair extracted into cyclohexane, carbon tetrachloride, benzene and n-butanol are very similar to that of chromate in aqueous solution. The absorption spectra of the chromium(VI)-capriquat extracts in these organic solvents gradually change to an absorption spectrum similar to that of HCrO(4)(-) in aqueous solution. Chromium(VI)-capriquat extracted into chloroform and 1,2-dichloroethane gives absorption spectra similar to that of HCrO(4)(-)in aqueous medium. The chromium(VI)-capriquat species extracted into 1,2-dichloroethane may be (Q(+))(2).CrO(4)(2-)(H(2)O)(n). In contrast, chromium(VI) is extracted with capriquat into the other organic solvents from ammoniacal medium as a mixture of (Q(+))(2).CrO(4)(2-)(H(2)O)(n) and Q(+).NH(4)(+).CrO(4)(2-)(H(2)O)(n). The spectral change is ascribed to the change of the extracted species from (Q(+))(2).CrO(4)(2-)(H(2)O)(n) and Q(+)NH(4)(+).CrO(4)(-)(H(2)O)(n) to Q(+).HCrO(4)(2-)(H(2)O)(n-1). The chromium(VI)-zephiramine species extracted is formulated as (Q(+), NH(4)(+))(2)CrO(4)(2-)(H(2)O)(n).(Q(+).Cl(-))(m). Molybdenum(VI) is extracted with capriquat into the same organic solvents as a mixture of (Q(+))(2).MoO(4)(2-)(H(2)O)(n) and Q(+).NH(4)(+).MoO(4)(2-).(H(2)O)(n).","Solvent extraction of the ion-pairs of chromium(VI) and molybdenum(VI) with trioctylmethylammonium chloride and benzyldimethylcetylammonium chloride Abs: The number of capriquat molecules per chromium(VI) atom in the chromate-capriquat ion-association complex has been found to be between one and two. The distribution ratio in the extraction of chromium(VI) with capriquat is dependent on the dielectric constant of the organic solvent, with a minimum at a dielectric constant of about 8. The absorption spectra of the ion-pair extracted into cyclohexane, carbon tetrachloride, benzene and n-butanol are very similar to that of chromate in aqueous solution. The absorption spectra of the chromium(VI)-capriquat extracts in these organic solvents gradually change to an absorption spectrum similar to that of HCrO(4)(-) in aqueous solution. Chromium(VI)-capriquat extracted into chloroform and 1,2-dichloroethane gives absorption spectra similar to that of HCrO(4)(-)in aqueous medium. The chromium(VI)-capriquat species extracted into 1,2-dichloroethane may be (Q(+))(2).CrO(4)(2-)(H(2)O)(n). In contrast, chromium(VI) is extracted with capriquat into the other organic solvents from ammoniacal medium as a mixture of (Q(+))(2).CrO(4)(2-)(H(2)O)(n) and Q(+).NH(4)(+).CrO(4)(2-)(H(2)O)(n). The spectral change is ascribed to the change of the extracted species from (Q(+))(2).CrO(4)(2-)(H(2)O)(n) and Q(+)NH(4)(+).CrO(4)(-)(H(2)O)(n) to Q(+).HCrO(4)(2-)(H(2)O)(n-1). The chromium(VI)-zephiramine species extracted is formulated as (Q(+), NH(4)(+))(2)CrO(4)(2-)(H(2)O)(n).(Q(+).Cl(-))(m). Molybdenum(VI) is extracted with capriquat into the same organic solvents as a mixture of (Q(+))(2).MoO(4)(2-)(H(2)O)(n) and Q(+).NH(4)(+).MoO(4)(2-).(H(2)O)(n)."
1509745,Kataoka et al. 1983,Catalytic determination of molybdenum(VI) by means of an iodide ion-selective electrode and a landolt-type hydrogen peroxide-iodide reaction,"A trace amount of molybdenum(VI) can be determined by using its catalytic effect on the oxidation of iodide to iodine by hydrogen peroxide in acidic medium. Addition of ascorbic acid added to the reaction mixture produces the Landolt effect, i.e., the iodine produced by the indicator reaction is reduced immediately by the ascorbic add. Hence the concentration of iodide begins to decrease once all the ascorbic acid has been consumed. The induction period is measured by monitoring the concentration of iodide ion with an iodide ion-selective electrode. The reciprocal of the induction period varies linearly with the concentration of molybdenum(VI). The most suitable pH and concentrations of hydrogen peroxide and potassium iodide are found to be 1.5, 5 and 10mM, respectively. An appropriate amount of ascorbic acid is added to the reaction mixture according to the concentration of molybdenum(VI) in the sample solution. A calibration graph with good proportionality is obtained for the molybdenum(VI) concentration range from 0.1 to 160 muM. Iron(III), vanadium(IV), zirconium(IV), tungsten(VI), copper(II) and chromium(VI) interfere, but iron(III) and copper(II) can be masked with EDTA.","Catalytic determination of molybdenum(VI) by means of an iodide ion-selective electrode and a landolt-type hydrogen peroxide-iodide reaction Abs: A trace amount of molybdenum(VI) can be determined by using its catalytic effect on the oxidation of iodide to iodine by hydrogen peroxide in acidic medium. Addition of ascorbic acid added to the reaction mixture produces the Landolt effect, i.e., the iodine produced by the indicator reaction is reduced immediately by the ascorbic add. Hence the concentration of iodide begins to decrease once all the ascorbic acid has been consumed. The induction period is measured by monitoring the concentration of iodide ion with an iodide ion-selective electrode. The reciprocal of the induction period varies linearly with the concentration of molybdenum(VI). The most suitable pH and concentrations of hydrogen peroxide and potassium iodide are found to be 1.5, 5 and 10mM, respectively. An appropriate amount of ascorbic acid is added to the reaction mixture according to the concentration of molybdenum(VI) in the sample solution. A calibration graph with good proportionality is obtained for the molybdenum(VI) concentration range from 0.1 to 160 muM. Iron(III), vanadium(IV), zirconium(IV), tungsten(VI), copper(II) and chromium(VI) interfere, but iron(III) and copper(II) can be masked with EDTA."
1509744,Osaki et al. 1983,Determination of chromium(vi) in natural waters by the sorption of chromium-diphenylcarbazone with xad-2 resin,"The sorption of the chromium(III)-diphenylcarbazone complex (Cr-DPC) with XAD-2 has been investigated, for use in the separation of Cr(VI) from Cr(III) species in natural waters. Cr-DPC is formed from the reaction of Cr(VI) with diphenylcarbazide, but Cr(III) species give no reaction in aqueous solution. The addition of sodium chloride or sodium beta-naphthalenesulphonate markedly enhances the sorption. The Cr-DPC sorbed on XAD-2 can be almost completely eluted with organic solvents, especially methanol, but about 5% of it is irreversibly sorbed and cannot be eluted. The excess of diphenylcarbazide and some of the organic matter in natural waters are also sorbed on XAD-2 but most of this can also be eluted with methanol. Organic matter which interferes with measurement of the absorbance of Cr-DPC can almost all be removed by extraction with chloroform. By use of these techniques, Cr(VI) in sea-water has been determined by the standard-addition method. Although about 50 litres of sea-water are necessary for the analysis, organic and colloidal Cr(III) species do not interfere.","Determination of chromium(vi) in natural waters by the sorption of chromium-diphenylcarbazone with xad-2 resin Abs: The sorption of the chromium(III)-diphenylcarbazone complex (Cr-DPC) with XAD-2 has been investigated, for use in the separation of Cr(VI) from Cr(III) species in natural waters. Cr-DPC is formed from the reaction of Cr(VI) with diphenylcarbazide, but Cr(III) species give no reaction in aqueous solution. The addition of sodium chloride or sodium beta-naphthalenesulphonate markedly enhances the sorption. The Cr-DPC sorbed on XAD-2 can be almost completely eluted with organic solvents, especially methanol, but about 5% of it is irreversibly sorbed and cannot be eluted. The excess of diphenylcarbazide and some of the organic matter in natural waters are also sorbed on XAD-2 but most of this can also be eluted with methanol. Organic matter which interferes with measurement of the absorbance of Cr-DPC can almost all be removed by extraction with chloroform. By use of these techniques, Cr(VI) in sea-water has been determined by the standard-addition method. Although about 50 litres of sea-water are necessary for the analysis, organic and colloidal Cr(III) species do not interfere."
1509743,Osaki et al. 1983,The effect of organic matter and colloidal particles on the determination of chromium(VI) in natural waters,"The chromium(VI) contents of two water samples, a river water and a sea-water, were determined by means of solvent extraction with APDC (ammonium pyrrolidinedithiocarbamate) into chloroform and by co-precipitation with iron(III) hydroxide. The analytical results depended on the separation method used, possibly because of differences in the behaviour of the chemical species of chromium in natural waters. Various chromium species, including simple inorganic ions, organic complexes, Cr(III) adsorbed on inorganic colloids and Cr(III) combined with organic polymers, were prepared, and their analytical characteristics were investigated.","The effect of organic matter and colloidal particles on the determination of chromium(VI) in natural waters Abs: The chromium(VI) contents of two water samples, a river water and a sea-water, were determined by means of solvent extraction with APDC (ammonium pyrrolidinedithiocarbamate) into chloroform and by co-precipitation with iron(III) hydroxide. The analytical results depended on the separation method used, possibly because of differences in the behaviour of the chemical species of chromium in natural waters. Various chromium species, including simple inorganic ions, organic complexes, Cr(III) adsorbed on inorganic colloids and Cr(III) combined with organic polymers, were prepared, and their analytical characteristics were investigated."
1509742,Battistoni et al. 1983,Silica gel with adsorbed Adogen 464 as an analytical sampling tool for anions,"A solid extractant made with the liquid anion-exchanger Adogen 464 supported on silica gel has been prepared and its potential as a resin-like exchange material has been evaluated. In acid media it furnishes a ready available, inexpensive tool for recovery of anionic metal complexes as well as simple anions and for elimination of complex matrices. Copper and cobalt have been recovered (with a concentration factor of 20) from sea-water, natural water, metal alloys and industrial electroplating baths and measured by atomic-absorption spectrophotometry. The detection limits for copper and cobalt are 0.2 and 0.4 ng ml respectively and interferences are minimal. Chromium(VI) has been separated from chromium(III), and a concentration factor of 40 and a detection limit of 0.2 ng ml have been achieved.","Silica gel with adsorbed Adogen 464 as an analytical sampling tool for anions Abs: A solid extractant made with the liquid anion-exchanger Adogen 464 supported on silica gel has been prepared and its potential as a resin-like exchange material has been evaluated. In acid media it furnishes a ready available, inexpensive tool for recovery of anionic metal complexes as well as simple anions and for elimination of complex matrices. Copper and cobalt have been recovered (with a concentration factor of 20) from sea-water, natural water, metal alloys and industrial electroplating baths and measured by atomic-absorption spectrophotometry. The detection limits for copper and cobalt are 0.2 and 0.4 ng ml respectively and interferences are minimal. Chromium(VI) has been separated from chromium(III), and a concentration factor of 40 and a detection limit of 0.2 ng ml have been achieved."
1509741,Donaldson 1980,"Determination of chromium in ores, rocks and related materials, iron, steel and non-ferrous alloys by atomic-absorption spectrophotometry after separation by tribenzylamine-chloroform extraction","A method for determining trace and moderate amounts of chromium in ores, concentrates, rocks, soils and clays is described. After fusion of the sample with sodium peroxide, the melt is dissolved in dilute sulphuric acid. The chromium(III) produced by the hydrogen peroxide formed is co-precipitated with hydrous ferric oxide. The precipitate is dissolved in 0.7M sulphuric acid and chromium oxidized to chromium(VI) with ceric ammonium sulphate. The chromium(VI) is extracted as an ion-association complex into chloroform containing tribenzylamine and stripped with ammoniacal hydrogen peroxide. This solution is acidified with perchloric acid and chromium determined by atomic-absorption spectrophotometry in an air-acetylene flame, at 357.9 nm. Barium and strontium do not interfere. The procedure is also applicable to iron and steel, and nickel-copper, aluminium and zirconium alloys. Up to 5 mg of manganese and 10 mg each of molybdenum and vanadium will not interfere. In the absence of vanadium, up to 10 mg of tungsten will not interfere. In the presence of 1 mg of vanadium, up to 1 mg of tungsten will not interfere.","Determination of chromium in ores, rocks and related materials, iron, steel and non-ferrous alloys by atomic-absorption spectrophotometry after separation by tribenzylamine-chloroform extraction Abs: A method for determining trace and moderate amounts of chromium in ores, concentrates, rocks, soils and clays is described. After fusion of the sample with sodium peroxide, the melt is dissolved in dilute sulphuric acid. The chromium(III) produced by the hydrogen peroxide formed is co-precipitated with hydrous ferric oxide. The precipitate is dissolved in 0.7M sulphuric acid and chromium oxidized to chromium(VI) with ceric ammonium sulphate. The chromium(VI) is extracted as an ion-association complex into chloroform containing tribenzylamine and stripped with ammoniacal hydrogen peroxide. This solution is acidified with perchloric acid and chromium determined by atomic-absorption spectrophotometry in an air-acetylene flame, at 357.9 nm. Barium and strontium do not interfere. The procedure is also applicable to iron and steel, and nickel-copper, aluminium and zirconium alloys. Up to 5 mg of manganese and 10 mg each of molybdenum and vanadium will not interfere. In the absence of vanadium, up to 10 mg of tungsten will not interfere. In the presence of 1 mg of vanadium, up to 1 mg of tungsten will not interfere."
1509740,Krishna and  Sastry 1979,A new spectrophotometric method for the determination of primary aromatic amines,"A new spectrophotometric method for the assay of primary aromatic amines with metol-chromium(VI) reagent has been developed. The method is simple, reproducible and accurate within +/- 1.0%. It has been extended to the determination of drugs (in pure samples and pharmaceutical preparations) which either contain a free primary aromatic amine or release it through hydrolysis or reduction. The method is also applicable to the assay of p-aminobenzenesulphonamides in rat urine and blood. All the sulphonamide derivatives tested, as well as other aniline derivatives with an electron-withdrawing group in the para-position, afford nearly the same molar absorptivity. Depending on the absorptivity, 0.3-2 mumole of amine will give an absorbance of approximately 0.1.","A new spectrophotometric method for the determination of primary aromatic amines Abs: A new spectrophotometric method for the assay of primary aromatic amines with metol-chromium(VI) reagent has been developed. The method is simple, reproducible and accurate within +/- 1.0%. It has been extended to the determination of drugs (in pure samples and pharmaceutical preparations) which either contain a free primary aromatic amine or release it through hydrolysis or reduction. The method is also applicable to the assay of p-aminobenzenesulphonamides in rat urine and blood. All the sulphonamide derivatives tested, as well as other aniline derivatives with an electron-withdrawing group in the para-position, afford nearly the same molar absorptivity. Depending on the absorptivity, 0.3-2 mumole of amine will give an absorbance of approximately 0.1."
1509739,Vernon and  Khorassani 1978,Solvent extraction of metals with hydroxamic acids,"Solvent extraction with hydroxamic acids has been investigated. with comparison of aliphatic and aromatic reagents for the extraction of iron, copper, cobalt and nickel. Caprylohydroxamic acid has been evaluated for use in extraction systems for titanium, vanadium, chromium, molybdenum and uranium, both in terms of acidity of aqueous phase and oxidation state of the metal. It has been established that caprylohydroxamic acid in 1-hexanol is a suitable extractant for the removal of titanium(IV), vanadium(V), chromium(VI), molybdenum(VI) and uranium(VI) from 6M hydrochloric acid.","Solvent extraction of metals with hydroxamic acids Abs: Solvent extraction with hydroxamic acids has been investigated. with comparison of aliphatic and aromatic reagents for the extraction of iron, copper, cobalt and nickel. Caprylohydroxamic acid has been evaluated for use in extraction systems for titanium, vanadium, chromium, molybdenum and uranium, both in terms of acidity of aqueous phase and oxidation state of the metal. It has been established that caprylohydroxamic acid in 1-hexanol is a suitable extractant for the removal of titanium(IV), vanadium(V), chromium(VI), molybdenum(VI) and uranium(VI) from 6M hydrochloric acid."
1509738,Yoshimura and  Ohashi 1978,Ion-exchanger colorimetry-II microdetermination of chromium in natural waters,"Ion-exchanger colorimetry for chromium(VI) with 1,5-diphenylcarbohydrazide has been developed for the determination of chromium at mug/l. concentrations in natural water samples. About 90% of the chromium(VI) in a 1-litre sample solution is concentrated in 200-400 mesh Dowex 50W-X4 resin within half an hour. It is possible to obtain higher sensitivity by employing a larger amount of sample solution. Total chromium can be determined by oxidizing chromium(III) to chromium(VI) with ceric sulphate.","Ion-exchanger colorimetry-II microdetermination of chromium in natural waters Abs: Ion-exchanger colorimetry for chromium(VI) with 1,5-diphenylcarbohydrazide has been developed for the determination of chromium at mug/l. concentrations in natural water samples. About 90% of the chromium(VI) in a 1-litre sample solution is concentrated in 200-400 mesh Dowex 50W-X4 resin within half an hour. It is possible to obtain higher sensitivity by employing a larger amount of sample solution. Total chromium can be determined by oxidizing chromium(III) to chromium(VI) with ceric sulphate."
1509737,Cresser and  Hargitt 1976,The significance of the CrO(4)2- chemical equilibrium HCr(4)- equilibrium in the determination of chromium(VI) by flame spectrometry,"Chromium atomic absorption for Cr(VI) solutions in the air-acetylene and air-hydrogen flames is pH-dependent, but not in the nitrous oxide-acetylene flame. The effect is shown to occur as a result of the HCrO(-)(4) chemical equilibrium CrO(2-)(4) equilibrium, and may cause significant errors in the determination of chromium by atomic-absorption Spectrometry unless the pH of sample and standard solutions is controlled.","The significance of the CrO(4)2- chemical equilibrium HCr(4)- equilibrium in the determination of chromium(VI) by flame spectrometry Abs: Chromium atomic absorption for Cr(VI) solutions in the air-acetylene and air-hydrogen flames is pH-dependent, but not in the nitrous oxide-acetylene flame. The effect is shown to occur as a result of the HCrO(-)(4) chemical equilibrium CrO(2-)(4) equilibrium, and may cause significant errors in the determination of chromium by atomic-absorption Spectrometry unless the pH of sample and standard solutions is controlled."
1509736,Iqbal and  Ejaz 1975,The use of 5-(4-pyridyl)nonane for the separation of chromium(vi) from fission products in hydrochloric acid media,"The distribution of chromium(VI) between 5-(4-pyridyl)nonane in benzene and hydrochloric acid media has been studied as a function of the concentration of the acid, extractant, chromium(VI), chloride and a few other ions. The extraction mechanism and the composition of the extracted complexes of Cr(VI) have been proposed. The separation of Cr(VI) from uranium, thorium and fission products in 3M hydrochloric acid has been achieved.","The use of 5-(4-pyridyl)nonane for the separation of chromium(vi) from fission products in hydrochloric acid media Abs: The distribution of chromium(VI) between 5-(4-pyridyl)nonane in benzene and hydrochloric acid media has been studied as a function of the concentration of the acid, extractant, chromium(VI), chloride and a few other ions. The extraction mechanism and the composition of the extracted complexes of Cr(VI) have been proposed. The separation of Cr(VI) from uranium, thorium and fission products in 3M hydrochloric acid has been achieved."
1509735,Adam and  Pribil 1974,Extractions with long-chain amines-VIII Colorimetric determination of chromium(VI) with diphenylcarbazide,"Traces of chromium(VI) are extracted from sulphuric acid solution into a chloroform solution of trioctylmethylammonium chloride. After the addition of solid diphenylcarbazide to the separated organic phase, a red colour is developed and is measured spectrophotometrically at 550 nm. A great number of common metals, including iron and copper, do not interfere when present in ratios up to at least 1:40,000 (chromium: metal).","Extractions with long-chain amines-VIII Colorimetric determination of chromium(VI) with diphenylcarbazide Abs: Traces of chromium(VI) are extracted from sulphuric acid solution into a chloroform solution of trioctylmethylammonium chloride. After the addition of solid diphenylcarbazide to the separated organic phase, a red colour is developed and is measured spectrophotometrically at 550 nm. A great number of common metals, including iron and copper, do not interfere when present in ratios up to at least 1:40,000 (chromium: metal)."
1509734,Rao and  Rao 1973,Hydrazine sulphate as reagent for titrimetric determination of vanadium(V) and chromium(VI),"Conditions have been developed for the direct titration of vanadium(V) and chromium(VI) with hydrazine sulphate, barium diphenylaminesulphonate being used as indicator and osmium tetroxide as catalyst.","Hydrazine sulphate as reagent for titrimetric determination of vanadium(V) and chromium(VI) Abs: Conditions have been developed for the direct titration of vanadium(V) and chromium(VI) with hydrazine sulphate, barium diphenylaminesulphonate being used as indicator and osmium tetroxide as catalyst."
1509733,Purushottam et al. 1973,Suppression of interference in the AAS determination of chromium by use of ammonium bifluoride,Addition of 1% of ammonium bifluoride successfully suppresses interference by diverse ions in the atomic-absorption determination of chromium(VI). If the sample solutions also contain chromium(III) addition of 1% of ammonium bifluoride and 0.2% of sodium sulphate is recommended for the suppression.,Suppression of interference in the AAS determination of chromium by use of ammonium bifluoride Abs: Addition of 1% of ammonium bifluoride successfully suppresses interference by diverse ions in the atomic-absorption determination of chromium(VI). If the sample solutions also contain chromium(III) addition of 1% of ammonium bifluoride and 0.2% of sodium sulphate is recommended for the suppression.
1509732,Fritz and  Sickafoose 1972,Rapid separation and determination of chromium,"Chromium(III) is oxidized to chromium(VI) at room temperature or by conventional persulphate oxidation. The chromium(VI) is separated from other metal ions by retention on a small anion-exchange column, and then eluted with a perchlorate solution and measured spectrophotometrically with a flow-through cell. The method is rapid, selective and amenable to automation.","Rapid separation and determination of chromium Abs: Chromium(III) is oxidized to chromium(VI) at room temperature or by conventional persulphate oxidation. The chromium(VI) is separated from other metal ions by retention on a small anion-exchange column, and then eluted with a perchlorate solution and measured spectrophotometrically with a flow-through cell. The method is rapid, selective and amenable to automation."
1509731,Rao et al. 1972,Ammonium hexanitratocerate(IV) as an oxidizing agent-VI Determination of chronuum(III) through oxidation to chromium(VI) at room temperature,"A new method has been developed for the determination of chromium(III), depending on its oxidation to chromium(VI) at room temperature by treatment with 50-100% excess of ammonium hexanitratocerate(IV) in 1.0M nitric acid medium. The reaction is complete within 15 min. The unreacted cerium(IV) is titrated potentiometrically with sodium oxalate.","Ammonium hexanitratocerate(IV) as an oxidizing agent-VI Determination of chronuum(III) through oxidation to chromium(VI) at room temperature Abs: A new method has been developed for the determination of chromium(III), depending on its oxidation to chromium(VI) at room temperature by treatment with 50-100% excess of ammonium hexanitratocerate(IV) in 1.0M nitric acid medium. The reaction is complete within 15 min. The unreacted cerium(IV) is titrated potentiometrically with sodium oxalate."
1509730,Donaldson 1970,"Determination of vanadium in refractory metals, steel, cast iron, alloys and silicates by extraction of an NBPHA complex from a sulphuric-hydrofluoric acid medium","A method for determining up to 0.15% of vanadium in high-purity niobium and tantalum metals, cast iron, steel, non-ferrous alloys and silicates is described. The proposed method is based on the extraction of a red vanadium(V)-N-benzoyl-N-phenylhydroxylamine complex into chloroform from a sulphuric-hydrofluoric acid medium containing excess of ammonium persulphate as oxidant. The molar absorptivity of the complex is 428 l.mole(-1).mm(-5) at 475 nm, the wavelength of maximum absorption. Interference from chromium(VI) and cerium(IV) is eliminated by reduction with iron(II). Common ions, including large amounts of titanium, zirconium, molybdenum and tungsten, do not interfere.","Determination of vanadium in refractory metals, steel, cast iron, alloys and silicates by extraction of an NBPHA complex from a sulphuric-hydrofluoric acid medium Abs: A method for determining up to 0.15% of vanadium in high-purity niobium and tantalum metals, cast iron, steel, non-ferrous alloys and silicates is described. The proposed method is based on the extraction of a red vanadium(V)-N-benzoyl-N-phenylhydroxylamine complex into chloroform from a sulphuric-hydrofluoric acid medium containing excess of ammonium persulphate as oxidant. The molar absorptivity of the complex is 428 l.mole(-1).mm(-5) at 475 nm, the wavelength of maximum absorption. Interference from chromium(VI) and cerium(IV) is eliminated by reduction with iron(II). Common ions, including large amounts of titanium, zirconium, molybdenum and tungsten, do not interfere."
1509729,Kirkbright and  Saw 1968,Spectrofluorimetric determination of microgram amounts of lead,"The violet fluorescence at 480 mmu of lead in concentrated hydrochloric acid-potassium chloride solution (excitation maximum 270 mmu) provides a method for the spectrofluorimetric determination of 10-60mug of lead. The optimum conditions for the determination have been established, and the effect of 31 foreign ions examined at the 50-fold molar excess level. The interference from iron(III) and vanadium(V) is eliminated by addition of tin(II) chloride, and that of chromium(VI) by treatment with sodium sulphite.","Spectrofluorimetric determination of microgram amounts of lead Abs: The violet fluorescence at 480 mmu of lead in concentrated hydrochloric acid-potassium chloride solution (excitation maximum 270 mmu) provides a method for the spectrofluorimetric determination of 10-60mug of lead. The optimum conditions for the determination have been established, and the effect of 31 foreign ions examined at the 50-fold molar excess level. The interference from iron(III) and vanadium(V) is eliminated by addition of tin(II) chloride, and that of chromium(VI) by treatment with sodium sulphite."
1509728,Graham et al. 2009,"Chromium occurrence and speciation in Baltimore harbor sediments and porewater, Baltimore, Maryland, USA","Industrial activities in the Baltimore Harbor, Baltimore, Maryland, USA, have resulted in widespread chromium contamination of sediments. A comprehensive analysis of Cr speciation in sediment and porewater collected from 22 locations in the Baltimore Harbor was completed to understand Cr bioavailability and probability of toxicity due to Cr in sediments. The analysis employed a reverse-phase ion-pair high-performance liquid chromatography-inductively coupled plasma-mass spectrometry (HPLC-ICP-MS) method. Sub-microgram-per-liter determination of Cr(III) and Cr(VI) in environmental samples was found, with method validation revealing broad method applicability of HPLC-ICP-MS to a wide range of sample types. The major limitation of the method was poor Cr species separation in high ionic strength solutions (greater than 0.1 M NaCl). Total Cr concentrations in Baltimore Harbor sediments ranged from 2.5 to 1,050 mg/kg with 11 of the 22 sites containing total Cr in excess of the 370 mg/ kg effects range-median (ER-M) sediment quality guideline. The Cr(VI) concentrations in sediments, however, were markedly lower, ranging from 0.10 to 0.38 mg/kg with Cr(VI) not detected in 14 of the 22 stations. Porewater concentrations, both for total Cr and Cr(VI), were quite low, with total Cr ranging from 0.20 to 2.16 microg/L and Cr(VI) ranging from 0.73 to 1.17 microg/L. The Cr(VI)-reducing capacity of the sediments, based on a sediment-spiking experiment, was found to be strongly correlated with the acid volatile sulfides content of the sediment. Overall, our results provide field validation of the hypothesis that Cr(VI) will not persist in sediments with excess acid volatile sulfides. Given the low concentrations of Cr(VI) in sediment and porewater, it appears unlikely that Cr in Baltimore Harbor sediments contributes appreciably to previously observed sediment toxicity.","Chromium occurrence and speciation in Baltimore harbor sediments and porewater, Baltimore, Maryland, USA Abs: Industrial activities in the Baltimore Harbor, Baltimore, Maryland, USA, have resulted in widespread chromium contamination of sediments. A comprehensive analysis of Cr speciation in sediment and porewater collected from 22 locations in the Baltimore Harbor was completed to understand Cr bioavailability and probability of toxicity due to Cr in sediments. The analysis employed a reverse-phase ion-pair high-performance liquid chromatography-inductively coupled plasma-mass spectrometry (HPLC-ICP-MS) method. Sub-microgram-per-liter determination of Cr(III) and Cr(VI) in environmental samples was found, with method validation revealing broad method applicability of HPLC-ICP-MS to a wide range of sample types. The major limitation of the method was poor Cr species separation in high ionic strength solutions (greater than 0.1 M NaCl). Total Cr concentrations in Baltimore Harbor sediments ranged from 2.5 to 1,050 mg/kg with 11 of the 22 sites containing total Cr in excess of the 370 mg/ kg effects range-median (ER-M) sediment quality guideline. The Cr(VI) concentrations in sediments, however, were markedly lower, ranging from 0.10 to 0.38 mg/kg with Cr(VI) not detected in 14 of the 22 stations. Porewater concentrations, both for total Cr and Cr(VI), were quite low, with total Cr ranging from 0.20 to 2.16 microg/L and Cr(VI) ranging from 0.73 to 1.17 microg/L. The Cr(VI)-reducing capacity of the sediments, based on a sediment-spiking experiment, was found to be strongly correlated with the acid volatile sulfides content of the sediment. Overall, our results provide field validation of the hypothesis that Cr(VI) will not persist in sediments with excess acid volatile sulfides. Given the low concentrations of Cr(VI) in sediment and porewater, it appears unlikely that Cr in Baltimore Harbor sediments contributes appreciably to previously observed sediment toxicity."
1509727,Kiran et al. 2008,Chromium (VI) tolerance in two halotolerant strains of Nostoc,"The present study reports on chromium (VI) tolerance of two cyanobacterial strains Nostoc linckia and Nostoc spongiaeforme isolated from salt affected soils using uni-algal and bi-algal systems. Besides distinct halophilism, the two strains exhibited remarkable tolerance to chromium (VI) and revealed 1.2 to 2.8 times more chlorophyll in the presence of the metal. While phycobilins and carotenoids also increased in Nostoc linckia with total dissolved salts (TDS) as well as metal, a decline was observed in Nostoc spongiaeforme in the presence of Cr (VI). Relative algal biomass (as % of control) showed significantly higher values (123-239) in Nostoc linckia in the presence of salt, metal and combination of the two. In Nostoc spongiaeforme it declined in the presence of metal (72-81) but increased in the presence of salts (143-249) and also in the binary systems (121-440). The bi-algal consortium showed relatively less tolerance to salt and metal stress. Nostoc linckia (20 day culture) showed upto 40% chromium removal whereas Nostoc spongiaeforme showed up to 12% removal, indicating greater suitability of the former for use in bioremediation studies.","Chromium (VI) tolerance in two halotolerant strains of Nostoc Abs: The present study reports on chromium (VI) tolerance of two cyanobacterial strains Nostoc linckia and Nostoc spongiaeforme isolated from salt affected soils using uni-algal and bi-algal systems. Besides distinct halophilism, the two strains exhibited remarkable tolerance to chromium (VI) and revealed 1.2 to 2.8 times more chlorophyll in the presence of the metal. While phycobilins and carotenoids also increased in Nostoc linckia with total dissolved salts (TDS) as well as metal, a decline was observed in Nostoc spongiaeforme in the presence of Cr (VI). Relative algal biomass (as % of control) showed significantly higher values (123-239) in Nostoc linckia in the presence of salt, metal and combination of the two. In Nostoc spongiaeforme it declined in the presence of metal (72-81) but increased in the presence of salts (143-249) and also in the binary systems (121-440). The bi-algal consortium showed relatively less tolerance to salt and metal stress. Nostoc linckia (20 day culture) showed upto 40% chromium removal whereas Nostoc spongiaeforme showed up to 12% removal, indicating greater suitability of the former for use in bioremediation studies."
1509726,Qureshi et al. 2009,Estimation of chromium(VI) sorption efficiency of novel regenerable p-tert-butylcalix[8]areneoctamide impregnated Amberlite resin,"The article describes a convenient synthesis and Cr(VI) extraction efficiency of a novel p-tert-butylcalix[8]areneoctamide impregnated Amberlite (XAD-4) resin. Using p-tert-butylcalix[8]arene macrocyclic building block, two strategies have been developed; i.e., derivatization of p-tert-butylcalix[8]arene framework with sophisticated ionophoric groups having efficiency to extract oxoanions from aqueous media and, impregnation of p-tert-butylcalix[8]arene derivative onto the polymeric support. Liquid-liquid and solid-liquid extraction experiments have been performed to evaluate the Cr(VI) extraction efficiency of both p-tert-butylcalix[8]arene derivative and the impregnated resin. From the results, it has been deduced that solid-phase extraction method is more convenient and efficient than liquid-liquid extraction process. The impregnated XAD-4 resin has been found regenerable with better extracting efficiency as compared to the simple p-tert-butylcalix[8]areneoctamide ionophore.","Estimation of chromium(VI) sorption efficiency of novel regenerable p-tert-butylcalix[8]areneoctamide impregnated Amberlite resin Abs: The article describes a convenient synthesis and Cr(VI) extraction efficiency of a novel p-tert-butylcalix[8]areneoctamide impregnated Amberlite (XAD-4) resin. Using p-tert-butylcalix[8]arene macrocyclic building block, two strategies have been developed; i.e., derivatization of p-tert-butylcalix[8]arene framework with sophisticated ionophoric groups having efficiency to extract oxoanions from aqueous media and, impregnation of p-tert-butylcalix[8]arene derivative onto the polymeric support. Liquid-liquid and solid-liquid extraction experiments have been performed to evaluate the Cr(VI) extraction efficiency of both p-tert-butylcalix[8]arene derivative and the impregnated resin. From the results, it has been deduced that solid-phase extraction method is more convenient and efficient than liquid-liquid extraction process. The impregnated XAD-4 resin has been found regenerable with better extracting efficiency as compared to the simple p-tert-butylcalix[8]areneoctamide ionophore."
1509725,Szmigielski et al. 2009,Non-carcinogenic carbon sorbents for respiratory protection,"Activated carbons impregnated with compounds of chromium, copper and silver (Cr-Cu-Ag) are widely used for removing toxic substances from air, mainly in respiratory protection for industrial and military applications. Toxicological and epidemiological studies have shown chromium (especially hexavalent Cr) to have carcinogenic properties. Hence, research has been launched to develop a new adsorption-catalytic complex without chromium, which is intended to replace the activated carbon-catalyst (Cr-Cu-Ag) system. In this work activated carbon obtained from plum stones as carrier and molybdenum, copper and silver salts as impregnates were studied. The porous structure of the carbon carrier was investigated using low temperature nitrogen adsorption. Cyanogen chloride breakthrough dynamics was analyzed in order to characterize the protection properties. Studies on the substitution of chromium by non-carcinogenic metals will be continued.","Non-carcinogenic carbon sorbents for respiratory protection Abs: Activated carbons impregnated with compounds of chromium, copper and silver (Cr-Cu-Ag) are widely used for removing toxic substances from air, mainly in respiratory protection for industrial and military applications. Toxicological and epidemiological studies have shown chromium (especially hexavalent Cr) to have carcinogenic properties. Hence, research has been launched to develop a new adsorption-catalytic complex without chromium, which is intended to replace the activated carbon-catalyst (Cr-Cu-Ag) system. In this work activated carbon obtained from plum stones as carrier and molybdenum, copper and silver salts as impregnates were studied. The porous structure of the carbon carrier was investigated using low temperature nitrogen adsorption. Cyanogen chloride breakthrough dynamics was analyzed in order to characterize the protection properties. Studies on the substitution of chromium by non-carcinogenic metals will be continued."
1509724,Han et al. 2008,Feasibility of using microalgal biomass cultured in domestic wastewater for the removal of chromium pollutants,"The feasibility of obtaining and using the biomass of a microalga, Chlorella miniata, from domestic wastewater (DW) cultures for the removal of chromium(III) [Cr(III)] and chromium(VI) [Cr(VI)] was compared with that from commercial Bristol medium (BM). Results showed that Chlorella miniata cultured in DW under 16-8 hours light-dark cycle [DW(16-8)] had similar growth to that in BM [BM(16-8)], but these two biomass had different biochemical compositions, and the former one had lower carbohydrate and higher protein content. When cultured in domestic wastewater, a higher biomass was obtained under continuous illumination [DW(24-0)], and the cells had higher carbohydrate and lower protein concentrations than that of DW(16-8). The spectra of the Fourier transform infrared spectrometer revealed that the functional groups on the surface of the three kinds of biomass--DW(16-8), DW(24-0), and BM(16-8)--were comparable, except an additional peak at 1731 cm(-1) was found in the biomass cultured in domestic wastewater, which was probably the result of bacterial contamination. Although biochemical differences were found among the three kinds of microalgal biomass, similar biosorption performances to chromium pollutants were recorded, with approximately 75% Cr(III) and 100% Cr(VI) removed at equilibrium in Cr(III) and Cr(VI) experiments, respectively, when dead biomass was used as a biosorbent. Therefore, it is possible to culture Chlorella miniata in domestic wastewater and use the biomass for the removal of chromium pollutants.","Feasibility of using microalgal biomass cultured in domestic wastewater for the removal of chromium pollutants Abs: The feasibility of obtaining and using the biomass of a microalga, Chlorella miniata, from domestic wastewater (DW) cultures for the removal of chromium(III) [Cr(III)] and chromium(VI) [Cr(VI)] was compared with that from commercial Bristol medium (BM). Results showed that Chlorella miniata cultured in DW under 16-8 hours light-dark cycle [DW(16-8)] had similar growth to that in BM [BM(16-8)], but these two biomass had different biochemical compositions, and the former one had lower carbohydrate and higher protein content. When cultured in domestic wastewater, a higher biomass was obtained under continuous illumination [DW(24-0)], and the cells had higher carbohydrate and lower protein concentrations than that of DW(16-8). The spectra of the Fourier transform infrared spectrometer revealed that the functional groups on the surface of the three kinds of biomass--DW(16-8), DW(24-0), and BM(16-8)--were comparable, except an additional peak at 1731 cm(-1) was found in the biomass cultured in domestic wastewater, which was probably the result of bacterial contamination. Although biochemical differences were found among the three kinds of microalgal biomass, similar biosorption performances to chromium pollutants were recorded, with approximately 75% Cr(III) and 100% Cr(VI) removed at equilibrium in Cr(III) and Cr(VI) experiments, respectively, when dead biomass was used as a biosorbent. Therefore, it is possible to culture Chlorella miniata in domestic wastewater and use the biomass for the removal of chromium pollutants."
1509723,Molokwane et al. 2008,Chromium (VI) reduction in activated sludge bacteria exposed to high chromium loading,"A mixed-culture of bacteria collected from a wastewater treatment plant in Brits, North-West Province (South Africa) biocatalytically reduced Cr(VI) at much higher concentrations than previously observed in cultures isolated in North America. Complete Cr(VI) reduction in aerobic cultures was achieved at a high concentration of 200 mg/L after incubation for only 65 hours. Under anaerobic conditions up to 150 mg, Cr(VI)/L was completely removed after incubating for 130 to 155 hours, still higher than the Cr(VI) reduction achieved with previous cultures where complete removal was only observed in cultures with the added Cr(VI) concentration not greater than 30 mg/L. Cr(VI) reduction capability of the cultures was verified in purified cultures. Consortium cultures were characterised using 16S rRNA partial sequence analysis. Results showed that the gram-positive Bacillus genera predominated under aerobic conditions with a small composition of the gram-negative Microbacterium sp. There was more biodiversity observed in the anaerobic cultures with the marked appearance of Enterococcus, Arthrobacter, Paenibacillus and Oceanobacillus species. The results showed that Cr(VI) reduction rate in the new culture was up to eight times higher than that previously observed in other Cr(VI) reducing cultures isolated from Cr(VI) contaminated soil environments in Newark (New Jersey) and other sites in North America.","Chromium (VI) reduction in activated sludge bacteria exposed to high chromium loading Abs: A mixed-culture of bacteria collected from a wastewater treatment plant in Brits, North-West Province (South Africa) biocatalytically reduced Cr(VI) at much higher concentrations than previously observed in cultures isolated in North America. Complete Cr(VI) reduction in aerobic cultures was achieved at a high concentration of 200 mg/L after incubation for only 65 hours. Under anaerobic conditions up to 150 mg, Cr(VI)/L was completely removed after incubating for 130 to 155 hours, still higher than the Cr(VI) reduction achieved with previous cultures where complete removal was only observed in cultures with the added Cr(VI) concentration not greater than 30 mg/L. Cr(VI) reduction capability of the cultures was verified in purified cultures. Consortium cultures were characterised using 16S rRNA partial sequence analysis. Results showed that the gram-positive Bacillus genera predominated under aerobic conditions with a small composition of the gram-negative Microbacterium sp. There was more biodiversity observed in the anaerobic cultures with the marked appearance of Enterococcus, Arthrobacter, Paenibacillus and Oceanobacillus species. The results showed that Cr(VI) reduction rate in the new culture was up to eight times higher than that previously observed in other Cr(VI) reducing cultures isolated from Cr(VI) contaminated soil environments in Newark (New Jersey) and other sites in North America."
1509722,Ozturk and  Aslim 2008,Relationship between chromium(VI) resistance and extracellular polymeric substances (EPS) concentration by some cyanobacterial isolates,"<strong>BACKGROUND, AIM, AND SCOPE: </strong>Chromium(VI) resistance and its association with extracellular polymeric substance (EPS) concentration in cyanobacteria was investigated. Increased EPS concentration was associated with Cr(VI) resistance. The most resistant isolate, Chroococcus sp. H(4), secreted the most EPS (427 mg/L).<br /><br /><strong>MATERIALS AND METHODS: </strong>EPS concentration of the two most resistant isolates (Chroococcus sp. H(4) and Synechocystis sp. S(63)) was investigated following exposure to 15 and 35 ppm Cr(VI). The composition of EPS produced by Chroococcus sp. H(4) following exposure to 10 ppm Cr(VI) was analyzed using high-performance liquid chromatography. Control EPS was composed of glucose (99%) and galactronic acid (1%); in the presence of 10 ppm Cr(VI), EPS composition changed to glucose (9%), xylose (75%), rhamnose (14%), and galacturonic acid (2%).<br /><br /><strong>RESULTS AND DISCUSSION: </strong>Results indicated that (1) exposure to elevated concentrations of Cr(VI) affected the composition of EPS produced by Chroococcus sp. H(4), and (2) there was a correlation between Cr(VI) resistance and EPS concentration in some cyanobacteria.","Relationship between chromium(VI) resistance and extracellular polymeric substances (EPS) concentration by some cyanobacterial isolates Abs: <strong>BACKGROUND, AIM, AND SCOPE: </strong>Chromium(VI) resistance and its association with extracellular polymeric substance (EPS) concentration in cyanobacteria was investigated. Increased EPS concentration was associated with Cr(VI) resistance. The most resistant isolate, Chroococcus sp. H(4), secreted the most EPS (427 mg/L).<br /><br /><strong>MATERIALS AND METHODS: </strong>EPS concentration of the two most resistant isolates (Chroococcus sp. H(4) and Synechocystis sp. S(63)) was investigated following exposure to 15 and 35 ppm Cr(VI). The composition of EPS produced by Chroococcus sp. H(4) following exposure to 10 ppm Cr(VI) was analyzed using high-performance liquid chromatography. Control EPS was composed of glucose (99%) and galactronic acid (1%); in the presence of 10 ppm Cr(VI), EPS composition changed to glucose (9%), xylose (75%), rhamnose (14%), and galacturonic acid (2%).<br /><br /><strong>RESULTS AND DISCUSSION: </strong>Results indicated that (1) exposure to elevated concentrations of Cr(VI) affected the composition of EPS produced by Chroococcus sp. H(4), and (2) there was a correlation between Cr(VI) resistance and EPS concentration in some cyanobacteria."
1509721,Domínguez-Renedo et al. 2008,Electrochemical determination of chromium(VI) using metallic nanoparticle-modified carbon screen-printed electrodes,"Carbon screen-printed electrodes (CSPEs) modified with metal nanoparticles present an interesting alternative in the determination of chromium(VI) by differential pulse voltammetry (DPV). Metallic silver and gold nanoparticle deposits have been obtained by electrochemical deposition. Scanning electron microscopy measurements show that the electrochemically synthesized silver and gold nanoparticles are deposited in aggregated form. The detection limit for the analytical procedures developed in this work were 8.5 x 10(-7) and 4.0 x 10(-7)M for silver and gold nanoparticle-modified CSPE, respectively. In terms of reproducibility, the precision of the above-mentioned method was calculated at 6.7% in %R.S.D. values for silver and 3.21% for gold nanoparticle CSPE.","Electrochemical determination of chromium(VI) using metallic nanoparticle-modified carbon screen-printed electrodes Abs: Carbon screen-printed electrodes (CSPEs) modified with metal nanoparticles present an interesting alternative in the determination of chromium(VI) by differential pulse voltammetry (DPV). Metallic silver and gold nanoparticle deposits have been obtained by electrochemical deposition. Scanning electron microscopy measurements show that the electrochemically synthesized silver and gold nanoparticles are deposited in aggregated form. The detection limit for the analytical procedures developed in this work were 8.5 x 10(-7) and 4.0 x 10(-7)M for silver and gold nanoparticle-modified CSPE, respectively. In terms of reproducibility, the precision of the above-mentioned method was calculated at 6.7% in %R.S.D. values for silver and 3.21% for gold nanoparticle CSPE."
1509720,Alta? 2009,Inhibitory effect of heavy metals on methane-producing anaerobic granular sludge,"Heavy metals could potentially have a negative impact on methane-producing anaerobic granular sludge. The objective of this study was to investigate the inhibitory effect of zinc(II), chromium(VI), nickel(II), and cadmium(II) on the methane-producing activity of granular sludge sampled from the upflow anaerobic sludge blanket reactor that treats the wastewaters of a yeast factory, for a range of concentrations between 0 and 128 mg L(-1). The modified Gompertz, Logistic, and Richards equations were applied to describe the inactivation of anaerobic culture by heavy metals. According to these models, the values of methane production potential (mL) for a heavy metal concentration of 128 mg L(-1) were in the following order: Ni (44.82+/-0.67)&gt;Cd (28.73+/-0.11)&gt;Cr (15.52+/-1.63)&gt;Zn (0.65+/-0.00). The IC(50) values, the metal concentrations that cause a 50% reduction in the cumulative methane production over a fixed period of exposure time (24h), for the individual heavy metals were found to be in the following order: Zn (most toxic; 7.5 mg L(-1))&gt;Cr (27 mg L(-1))&gt;Ni (35 mg L(-1)) approximately Cd (least toxic; 36 mg L(-1)).","Inhibitory effect of heavy metals on methane-producing anaerobic granular sludge Abs: Heavy metals could potentially have a negative impact on methane-producing anaerobic granular sludge. The objective of this study was to investigate the inhibitory effect of zinc(II), chromium(VI), nickel(II), and cadmium(II) on the methane-producing activity of granular sludge sampled from the upflow anaerobic sludge blanket reactor that treats the wastewaters of a yeast factory, for a range of concentrations between 0 and 128 mg L(-1). The modified Gompertz, Logistic, and Richards equations were applied to describe the inactivation of anaerobic culture by heavy metals. According to these models, the values of methane production potential (mL) for a heavy metal concentration of 128 mg L(-1) were in the following order: Ni (44.82+/-0.67)&gt;Cd (28.73+/-0.11)&gt;Cr (15.52+/-1.63)&gt;Zn (0.65+/-0.00). The IC(50) values, the metal concentrations that cause a 50% reduction in the cumulative methane production over a fixed period of exposure time (24h), for the individual heavy metals were found to be in the following order: Zn (most toxic; 7.5 mg L(-1))&gt;Cr (27 mg L(-1))&gt;Ni (35 mg L(-1)) approximately Cd (least toxic; 36 mg L(-1))."
1509719,Olmez 2009,The optimization of Cr(VI) reduction and removal by electrocoagulation using response surface methodology,"In this study Response Surface Methodology (RSM) was employed to investigate the effects of different operating conditions on the removal of hexavalent chromium (Cr(VI)) by the electrocoagulation with stainless steel electrodes. Central Composite Design (CCD) was used for the optimization of the electrocoagulation process and to evaluate the effects and interactions of process variables: applied electric current, electrolyte concentration and application time on the removal of Cr(VI). A sample of metal finishing industry wastewater having a high Cr(VI) concentration of 1470 mg/L was used in the experimental study. The optimum conditions for complete (100%) Cr(VI) removal were established as 7.4A applied electric current, 33.6 mM electrolyte (NaCl) concentration and 70 min application time. The amount of sludge produced under the conditions optimized based on the results from the model was lower than the amount generated by chemical treatment with FeSO(4).7H(2)O and non-hazardous in nature.","The optimization of Cr(VI) reduction and removal by electrocoagulation using response surface methodology Abs: In this study Response Surface Methodology (RSM) was employed to investigate the effects of different operating conditions on the removal of hexavalent chromium (Cr(VI)) by the electrocoagulation with stainless steel electrodes. Central Composite Design (CCD) was used for the optimization of the electrocoagulation process and to evaluate the effects and interactions of process variables: applied electric current, electrolyte concentration and application time on the removal of Cr(VI). A sample of metal finishing industry wastewater having a high Cr(VI) concentration of 1470 mg/L was used in the experimental study. The optimum conditions for complete (100%) Cr(VI) removal were established as 7.4A applied electric current, 33.6 mM electrolyte (NaCl) concentration and 70 min application time. The amount of sludge produced under the conditions optimized based on the results from the model was lower than the amount generated by chemical treatment with FeSO(4).7H(2)O and non-hazardous in nature."
1509718,Ibarrolaza et al. 2009,Dynamics of microbial community during bioremediation of phenanthrene and chromium(VI)-contaminated soil microcosms,"The combined effect of phenanthrene and Cr(VI) on soil microbial activity, community composition and on the efficiency of bioremediation processes has been studied. Biometer flask systems and soil microcosm systems contaminated with 2,000 mg of phenanthrene per kg of dry soil and different Cr(VI) concentrations were investigated. Temperature, soil moisture and oxygen availability were controlled to support bioremediation. Cr(VI) inhibited the phenanthrene mineralization (CO(2) production) and cultivable PAH degrading bacteria at levels of 500-2,600 mg kg(-1). In the bioremediation experiments in soil microcosms the degradation of phenanthrene, the dehydrogenase activity and the increase in PAH degrading bacteria counts were retarded by the presence of Cr(VI) at all studied concentrations (25, 50 and 100 mg kg(-1)). These negative effects did not show a correlation with Cr(VI) concentration. Whereas the presence of Cr(VI) had a negative effect on the phenanthrene elimination rate, co-contamination with phenanthrene reduced the residual Cr(VI) concentration in the water exchangeable Cr(VI) fraction (WEF) in comparison with the soil microcosm contaminated only with Cr(VI). Clear differences were found between the denaturing gradient gel electrophoresis (DGGE) patterns of each soil microcosm, showing that the presence of different Cr(VI) concentrations did modulate the community response to phenanthrene and caused perdurable changes in the structure of the microbial soil community.","Dynamics of microbial community during bioremediation of phenanthrene and chromium(VI)-contaminated soil microcosms Abs: The combined effect of phenanthrene and Cr(VI) on soil microbial activity, community composition and on the efficiency of bioremediation processes has been studied. Biometer flask systems and soil microcosm systems contaminated with 2,000 mg of phenanthrene per kg of dry soil and different Cr(VI) concentrations were investigated. Temperature, soil moisture and oxygen availability were controlled to support bioremediation. Cr(VI) inhibited the phenanthrene mineralization (CO(2) production) and cultivable PAH degrading bacteria at levels of 500-2,600 mg kg(-1). In the bioremediation experiments in soil microcosms the degradation of phenanthrene, the dehydrogenase activity and the increase in PAH degrading bacteria counts were retarded by the presence of Cr(VI) at all studied concentrations (25, 50 and 100 mg kg(-1)). These negative effects did not show a correlation with Cr(VI) concentration. Whereas the presence of Cr(VI) had a negative effect on the phenanthrene elimination rate, co-contamination with phenanthrene reduced the residual Cr(VI) concentration in the water exchangeable Cr(VI) fraction (WEF) in comparison with the soil microcosm contaminated only with Cr(VI). Clear differences were found between the denaturing gradient gel electrophoresis (DGGE) patterns of each soil microcosm, showing that the presence of different Cr(VI) concentrations did modulate the community response to phenanthrene and caused perdurable changes in the structure of the microbial soil community."
1509717,Shi and  Kan 2009,Study on the properties of chromium residue-cement matrices (CRCM) and the influences of superplasticizers on chromium(VI)-immobilising capability of cement matrices,"The study of cementitious activity of chromium residue (CR) was carried out to formulate the properties of chromium residue-cement matrices (CRCM) by blending CR with Ordinary Portland Cement (OPC). The particle size distribution, microstructures of CR were investigated by some apparatuses, and physical properties, leaching behavior of hexavalent chromium [Cr(VI)] of CRCM were also determined by some experiments. Three types of commonly used superplasticizers (sulphonated acetone formaldehyde superplasticizer (J1), polycarboxylate-based superplasticizer (J2) and naphthalene superplasticizer (J3)) were chosen to investigate their influences on the physical properties and the Cr(VI)-immobilisation in the leachate of the CRCM hardened pastes. The results show that the CR has a certain cementitious activity. The incorporation of CR improves the pore size distribution of CRCM. The Cr(VI) concentrations in the leachate of CRCM significantly decrease by incorporation of J2. Among three superplasticizers, J2 achieves lowest Cr(VI) leaching ratio. Based on this study, it is likely to develop CR as a potential new additive used in cement-based materials.","Study on the properties of chromium residue-cement matrices (CRCM) and the influences of superplasticizers on chromium(VI)-immobilising capability of cement matrices Abs: The study of cementitious activity of chromium residue (CR) was carried out to formulate the properties of chromium residue-cement matrices (CRCM) by blending CR with Ordinary Portland Cement (OPC). The particle size distribution, microstructures of CR were investigated by some apparatuses, and physical properties, leaching behavior of hexavalent chromium [Cr(VI)] of CRCM were also determined by some experiments. Three types of commonly used superplasticizers (sulphonated acetone formaldehyde superplasticizer (J1), polycarboxylate-based superplasticizer (J2) and naphthalene superplasticizer (J3)) were chosen to investigate their influences on the physical properties and the Cr(VI)-immobilisation in the leachate of the CRCM hardened pastes. The results show that the CR has a certain cementitious activity. The incorporation of CR improves the pore size distribution of CRCM. The Cr(VI) concentrations in the leachate of CRCM significantly decrease by incorporation of J2. Among three superplasticizers, J2 achieves lowest Cr(VI) leaching ratio. Based on this study, it is likely to develop CR as a potential new additive used in cement-based materials."
1509716,Hagendorfer and  Goessler 2008,Separation of chromium(III) and chromium(VI) by ion chromatography and an inductively coupled plasma mass spectrometer as element-selective detector,"Due to its extensive use in industrial processes, large quantities of chromium compounds are discharged into the environment. Common approaches for the speciation of Cr employ the determination of Cr(VI) and total Cr. The focus of the present work was a separation of Cr(III) and Cr(VI) species, with a minimum of sample preparation, by keeping an eye on the more relevant and toxic Cr(VI). For the successful simultaneous separation of both chromium species we implemented a RSpak NN-814 4DP (PEEK, 4 mm x 150 mm) multi-mode column using an eluent containing 90 mM ammonium sulfate and 10 mM ammonium nitrate, adjusted to pH 3.5. At a flow of 0.3 mL min(-1) the separation of both Cr species was possible within 8 min. Further the octopole reaction system of the inductively coupled plasma mass spectrometer was systematically studied and optimised to reduce the influence of polyatomic interferences. The major advantage of the developed method compared to published methods is that a derivatisation of the Cr(III) species--an invasion in the speciation--is not required. With the used multi-mode column both chromium species are retained. Furthermore the pH of the mobile phase (pH 3.5) prevents reduction of Cr(VI) as well as precipitation of Cr(III) during the analysis. A limit of determination of approximately 0.5 microg L(-1) for both chromium species with an injection volume of 25 microL was obtained. The optimised method was successfully applied to the determination of Cr(VI) in cement samples as well as chromium speciation analysis in homeopathic drugs.","Separation of chromium(III) and chromium(VI) by ion chromatography and an inductively coupled plasma mass spectrometer as element-selective detector Abs: Due to its extensive use in industrial processes, large quantities of chromium compounds are discharged into the environment. Common approaches for the speciation of Cr employ the determination of Cr(VI) and total Cr. The focus of the present work was a separation of Cr(III) and Cr(VI) species, with a minimum of sample preparation, by keeping an eye on the more relevant and toxic Cr(VI). For the successful simultaneous separation of both chromium species we implemented a RSpak NN-814 4DP (PEEK, 4 mm x 150 mm) multi-mode column using an eluent containing 90 mM ammonium sulfate and 10 mM ammonium nitrate, adjusted to pH 3.5. At a flow of 0.3 mL min(-1) the separation of both Cr species was possible within 8 min. Further the octopole reaction system of the inductively coupled plasma mass spectrometer was systematically studied and optimised to reduce the influence of polyatomic interferences. The major advantage of the developed method compared to published methods is that a derivatisation of the Cr(III) species--an invasion in the speciation--is not required. With the used multi-mode column both chromium species are retained. Furthermore the pH of the mobile phase (pH 3.5) prevents reduction of Cr(VI) as well as precipitation of Cr(III) during the analysis. A limit of determination of approximately 0.5 microg L(-1) for both chromium species with an injection volume of 25 microL was obtained. The optimised method was successfully applied to the determination of Cr(VI) in cement samples as well as chromium speciation analysis in homeopathic drugs."
1509715,Jena and  Raj 2008,Highly sensitive and selective electrochemical detection of sub-ppb level chromium(VI) using nano-sized gold particle,Gold nanoparticle based nanostructured electrode has been developed for the amperometric detection of ultratrace amount of toxic Cr(VI). The nano-sized Au particles have been grown on a conducting substrate modified with sol-gel-derived thiol functionalized silicate network and used for the electroanalysis of Cr(VI). The nanostructured interface show well-defined voltammetric peak for the reduction of Cr(VI) at approximately 0.4 V. The voltammetric behavior of Cr(VI) strongly depends on the coverage of nanoparticle on the electrode surface. Constant potential amperometry has been used for the detection of Cr(VI) at well below the guideline value set by World Health Organization (WHO). This electrode is highly sensitive (30+/-0.2 nA/ppb) and the detection limit (S/N=9) was 0.1 ppb. Cr(III) and coexisting other metal ions and surface active agent present in water do not interfere with the amperometric measurement of Cr(VI). This nanostructured electrode is highly stable and it can be used for continuous measurement of Cr(VI) without using any pretreatment or activation procedures. The accuracy of the measurement has been validated by measuring the concentration of Cr(VI) in the certified reference material (CRM).,Highly sensitive and selective electrochemical detection of sub-ppb level chromium(VI) using nano-sized gold particle Abs: Gold nanoparticle based nanostructured electrode has been developed for the amperometric detection of ultratrace amount of toxic Cr(VI). The nano-sized Au particles have been grown on a conducting substrate modified with sol-gel-derived thiol functionalized silicate network and used for the electroanalysis of Cr(VI). The nanostructured interface show well-defined voltammetric peak for the reduction of Cr(VI) at approximately 0.4 V. The voltammetric behavior of Cr(VI) strongly depends on the coverage of nanoparticle on the electrode surface. Constant potential amperometry has been used for the detection of Cr(VI) at well below the guideline value set by World Health Organization (WHO). This electrode is highly sensitive (30+/-0.2 nA/ppb) and the detection limit (S/N=9) was 0.1 ppb. Cr(III) and coexisting other metal ions and surface active agent present in water do not interfere with the amperometric measurement of Cr(VI). This nanostructured electrode is highly stable and it can be used for continuous measurement of Cr(VI) without using any pretreatment or activation procedures. The accuracy of the measurement has been validated by measuring the concentration of Cr(VI) in the certified reference material (CRM).
1509714,Jain et al. 2009,Chromium(VI) removal from aqueous system using Helianthus annuus (sunflower) stem waste,"The objective of this study was to investigate the Cr(VI) removal efficiency of sunflower waste from aqueous system under different process conditions. Two adsorbents were prepared by pre-treating the sunflower stem waste. One adsorbent was prepared by boiling it and second adsorbent was prepared by treating it with formaldehyde. Batch mode experiments were carried out as a function of solution pH, adsorbent dosage, Cr(VI) concentration and contact time. FT-IR spectra and SEMs of the adsorbents were recorded to explore the number and position of functional groups available for the binding of Cr(VI) ions and morphology of the studied adsorbents. The removal of chromium was dependent on the physico-chemical characteristics of the adsorbent, adsorbate concentration and other studied process parameters. Maximum metal removal was observed at pH 2.0. The efficiencies of boiled sunflower stem absorbent and formaldehyde-treated sunflower stem absorbent for the removal of Cr(VI) were 81.7 and 76.5%, respectively for dilute solutions at 4.0g/L adsorbent dose. The applicability of Langmuir, Freundlich and Dubinin-Radushkevich isotherms was also tested. The results revealed that the hexavalent chromium is considerably adsorbed on sunflower stem and it could be an economical method for the removal of hexavalent chromium from aqueous systems.","Chromium(VI) removal from aqueous system using Helianthus annuus (sunflower) stem waste Abs: The objective of this study was to investigate the Cr(VI) removal efficiency of sunflower waste from aqueous system under different process conditions. Two adsorbents were prepared by pre-treating the sunflower stem waste. One adsorbent was prepared by boiling it and second adsorbent was prepared by treating it with formaldehyde. Batch mode experiments were carried out as a function of solution pH, adsorbent dosage, Cr(VI) concentration and contact time. FT-IR spectra and SEMs of the adsorbents were recorded to explore the number and position of functional groups available for the binding of Cr(VI) ions and morphology of the studied adsorbents. The removal of chromium was dependent on the physico-chemical characteristics of the adsorbent, adsorbate concentration and other studied process parameters. Maximum metal removal was observed at pH 2.0. The efficiencies of boiled sunflower stem absorbent and formaldehyde-treated sunflower stem absorbent for the removal of Cr(VI) were 81.7 and 76.5%, respectively for dilute solutions at 4.0g/L adsorbent dose. The applicability of Langmuir, Freundlich and Dubinin-Radushkevich isotherms was also tested. The results revealed that the hexavalent chromium is considerably adsorbed on sunflower stem and it could be an economical method for the removal of hexavalent chromium from aqueous systems."
1509713,Quintelas et al. 2009,Treatment of chromium(VI) solutions in a pilot-scale bioreactor through a biofilm of Arthrobacter viscosus supported on GAC,"The aim of this work is to evaluate the applicability of a biofilm to the removal of chromium in solution, at a pilot scale. The effect of the initial concentration of metal on the biosorption behavior of an Arthrobacter viscosus biofilm supported on granular activated carbon, in batch and column essays was also analyzed. Six isotherm equations have been tested in the present study. The best fit was obtained with the Freundlich model. It was observed that as the initial chromium concentration increases, the uptake increases too, but the removal percentage decreases, with values between 95.20% (C(0)=5mg/l) and 38.28% (C(0)=1000 mg/l). The batch adsorption studies were used to develop a pilot bioreactor able to remove chromium from aqueous solutions. Data obtained in a pilot-scale reactor showed an average removal percentage of 99.9%, during the first 30 days, for the initial concentration of 10mg/l and an average removal percentage of 72%, for the same period and for the initial concentration of 100mg/l. Uptake values of 11.35 mg/g and 14.55 mg/g were obtained, respectively, for the initial concentration of 10 and 100mg/l. The results obtained are very promising and encourage the utilization of this biofilm in environmental applications.","Treatment of chromium(VI) solutions in a pilot-scale bioreactor through a biofilm of Arthrobacter viscosus supported on GAC Abs: The aim of this work is to evaluate the applicability of a biofilm to the removal of chromium in solution, at a pilot scale. The effect of the initial concentration of metal on the biosorption behavior of an Arthrobacter viscosus biofilm supported on granular activated carbon, in batch and column essays was also analyzed. Six isotherm equations have been tested in the present study. The best fit was obtained with the Freundlich model. It was observed that as the initial chromium concentration increases, the uptake increases too, but the removal percentage decreases, with values between 95.20% (C(0)=5mg/l) and 38.28% (C(0)=1000 mg/l). The batch adsorption studies were used to develop a pilot bioreactor able to remove chromium from aqueous solutions. Data obtained in a pilot-scale reactor showed an average removal percentage of 99.9%, during the first 30 days, for the initial concentration of 10mg/l and an average removal percentage of 72%, for the same period and for the initial concentration of 100mg/l. Uptake values of 11.35 mg/g and 14.55 mg/g were obtained, respectively, for the initial concentration of 10 and 100mg/l. The results obtained are very promising and encourage the utilization of this biofilm in environmental applications."
1509712,Clive et al. 2008,Formal radical closure onto aromatic rings--a general route to carbocycles,"A general method is described for indirectly effecting radical carbocyclization of an alkyl chain onto an aromatic ring. Birch reductive-alkylation of aromatic tert-butyl esters with alpha,omega-dibromides, chromium(vi)-mediated oxidation of the resulting 1,4-dienes and Finkelstein displacement of Br(-) with NaI gives cross-conjugated ketones that undergo radical cyclization. The products are easily aromatized to phenols by silylation, Saegusa oxidation and treatment with BiCl(3).H(2)O. A special feature of the route is that it allows attachment of a substituent to the original aromatic ring in place of the phenolic oxygen of the normal product.","Formal radical closure onto aromatic rings--a general route to carbocycles Abs: A general method is described for indirectly effecting radical carbocyclization of an alkyl chain onto an aromatic ring. Birch reductive-alkylation of aromatic tert-butyl esters with alpha,omega-dibromides, chromium(vi)-mediated oxidation of the resulting 1,4-dienes and Finkelstein displacement of Br(-) with NaI gives cross-conjugated ketones that undergo radical cyclization. The products are easily aromatized to phenols by silylation, Saegusa oxidation and treatment with BiCl(3).H(2)O. A special feature of the route is that it allows attachment of a substituent to the original aromatic ring in place of the phenolic oxygen of the normal product."
1509711,Yu et al. 2008,Fabrication of a TiO2-BDD heterojunction and its application as a photocatalyst for the simultaneous oxidation of an azo dye and reduction of Cr(VI),"A TiO2-boron doped diamond (TiO2-BDD) heterojunction was employed as a photocatalyst to simultaneously oxidize an azo dye C.I. reactive yellow 15 (RY15) and reduce hexavalent chromium (Cr(VI)). This heterojunction was fabricated first by depositing a BDD film on a Ti sheet in a hot filament chemical vapor deposition reactor, followed by covering a layer of TiO2 in a metal-organic chemical vapor deposition system. The morphology of this heterojunction was characterized by using a scanning electron microscope (SEM). X-ray diffraction (XRD), Raman spectroscopy, and current-voltage (I-V) measurement were used to characterize its structures. Additionally, the characterization of surface photovoltage showed that the TiO2-BDD heterojunction exhibited a higher photovoltage response and a better ability for charge separation than the photocatalyst of TiO2 directly deposited on a Ti sheet (TiO2-Ti). The photocatalytic experiments revealed that the kinetic constants for the oxidation of RY15 and the reduction of Cr(VI) were, respectively, increased by 85 and 71% when the photocatalyst of TiO2-Ti was replaced by the TiO2-BDD heterojunction. Meanwhile, a significant synergy was confirmed in the simultaneous oxidation of RY15 and reduction of Cr(VI). The enhanced photocatalytic ability of the TiO2-BDD composite could be attributed to the heterojunction. The possible photocatalytic mechanism was also discussed.","Fabrication of a TiO2-BDD heterojunction and its application as a photocatalyst for the simultaneous oxidation of an azo dye and reduction of Cr(VI) Abs: A TiO2-boron doped diamond (TiO2-BDD) heterojunction was employed as a photocatalyst to simultaneously oxidize an azo dye C.I. reactive yellow 15 (RY15) and reduce hexavalent chromium (Cr(VI)). This heterojunction was fabricated first by depositing a BDD film on a Ti sheet in a hot filament chemical vapor deposition reactor, followed by covering a layer of TiO2 in a metal-organic chemical vapor deposition system. The morphology of this heterojunction was characterized by using a scanning electron microscope (SEM). X-ray diffraction (XRD), Raman spectroscopy, and current-voltage (I-V) measurement were used to characterize its structures. Additionally, the characterization of surface photovoltage showed that the TiO2-BDD heterojunction exhibited a higher photovoltage response and a better ability for charge separation than the photocatalyst of TiO2 directly deposited on a Ti sheet (TiO2-Ti). The photocatalytic experiments revealed that the kinetic constants for the oxidation of RY15 and the reduction of Cr(VI) were, respectively, increased by 85 and 71% when the photocatalyst of TiO2-Ti was replaced by the TiO2-BDD heterojunction. Meanwhile, a significant synergy was confirmed in the simultaneous oxidation of RY15 and reduction of Cr(VI). The enhanced photocatalytic ability of the TiO2-BDD composite could be attributed to the heterojunction. The possible photocatalytic mechanism was also discussed."
1509710,Vernay et al. 2008,Effect of chromium species on phytochemical and physiological parameters in Datura innoxia,"In soil, chromium can be found in two main valence states: hexavalent Cr(VI) and trivalent Cr(III). In this study, we investigated the impact of Cr on photosynthetic gas exchange, photosystem II (PSII) activity, Cr translocation and accumulation, proline content and alkaloids production, i.e. scopolamine and hyoscyamine, in Datura innoxia. Cr uptake was influenced by its oxidation state and its concentration in growth medium. The plant roots were determined as being the main organ of Cr accumulation. Cr(VI) was more toxic than Cr(III) as indicated by reduction in plant biomass and net photosynthesis. The stomatal conductance showed a similar trend to that of photosynthetic capacity. Cr(III) and Cr(VI) had a different impact on substomatal CO(2) concentration then Cr toxicity was related to its oxidation states. In plants stressed with a Cr(VI) excess, a down regulation of PSII activity was observed with an impairment of photochemical activity. Indeed, the maximum quantum yield of PSII (F(v)/F(m)), the quantum yield of PSII (PhiPSII) and the efficiency of excitation capture by open centers (F'(v)/F'(m)) decreased. Cr(III) had little effects on PSII primary photochemistry, whatever its form induces an increase of scopolamine content without changes in hyoscyamine content in leaves of D. innoxia. These results provide that chromium contamination can change the secondary metabolites composition of leaves, thereby, impacting the quality, safety and efficacy of natural plant products synthesized by D. innoxia plants.","Effect of chromium species on phytochemical and physiological parameters in Datura innoxia Abs: In soil, chromium can be found in two main valence states: hexavalent Cr(VI) and trivalent Cr(III). In this study, we investigated the impact of Cr on photosynthetic gas exchange, photosystem II (PSII) activity, Cr translocation and accumulation, proline content and alkaloids production, i.e. scopolamine and hyoscyamine, in Datura innoxia. Cr uptake was influenced by its oxidation state and its concentration in growth medium. The plant roots were determined as being the main organ of Cr accumulation. Cr(VI) was more toxic than Cr(III) as indicated by reduction in plant biomass and net photosynthesis. The stomatal conductance showed a similar trend to that of photosynthetic capacity. Cr(III) and Cr(VI) had a different impact on substomatal CO(2) concentration then Cr toxicity was related to its oxidation states. In plants stressed with a Cr(VI) excess, a down regulation of PSII activity was observed with an impairment of photochemical activity. Indeed, the maximum quantum yield of PSII (F(v)/F(m)), the quantum yield of PSII (PhiPSII) and the efficiency of excitation capture by open centers (F'(v)/F'(m)) decreased. Cr(III) had little effects on PSII primary photochemistry, whatever its form induces an increase of scopolamine content without changes in hyoscyamine content in leaves of D. innoxia. These results provide that chromium contamination can change the secondary metabolites composition of leaves, thereby, impacting the quality, safety and efficacy of natural plant products synthesized by D. innoxia plants."
1509709,Arakawa and  Tang 2008,Recognition and incision of Cr(III) ligand-conjugated DNA adducts by the nucleotide excision repair proteins UvrABC: importance of the Cr(III)-purine moiety in the enzymatic reaction,"Hexavalent chromium [Cr(VI)] is an ubiquitous environmental contaminant and a well-known etiological agent of human lung cancer. Inside human cells, Cr(VI) is reduced to Cr(III), which can conjugate with amino acids, ascorbic acids, and glutathiones in the cytoplasm. Conjugated and unconjugated Cr(III) can enter the nucleus to form adducts with DNA and electrostatically interact with the phosphate group of DNA. It has been found that in both human and Escherichia coli systems, Cr(III) ligand-conjugated DNA ternary adducts are efficiently repaired by the nucleotide excision repair (NER) pathway. In contrast, DNA adducts formed by unconjugated Cr(III) with DNA are repaired significantly less efficiently by the NER system. These results raise the possibility that the NER system repairs Cr(III) ligand-conjugated DNA adducts and biadducts such as Cr(III)-guanine-phosphate adducts but not Cr(III)-phosphate adducts. To test this hypothesis, we determined the cutting efficiency and the mode of cutting of DNA modified with tannin-conjugated Cr(III) by the E. coli NER enzymes UvrABC. Tannin compounds, gallic acid (GA), and ethyl gallate (EGA) can reduce Cr(VI) to Cr(III) to form Cr(III)-GA 2 and Cr(III)-EGA 2, respectively, which can interact with a single guanine or adenine base but not with the DNA phosphate backbone. We found that UvrABC is able to incise Cr(III)-GA 2- and Cr(III)-EGA 2-modified plasmid DNA, and the amount of incision increased as a function of tannin concentration used for modifications. In contrast, UvrABC nuclease does not incise GA- and EGA-modified plasmid DNA. Mapping the sequence specificity of Cr(III)-GA 2- and Cr(III)-EGA 2-DNA formation in the human p53 gene sequence by UvrABC nuclease cutting, we found that the sequence specificity for both adducts is the same but is much more selective than Cr(III)-guanine-DNA adducts. Together, these results suggest that NER proteins from E. coli recognize the purine-Cr(III) adduct but not the Cr(III)-backbone phosphate complex.","Recognition and incision of Cr(III) ligand-conjugated DNA adducts by the nucleotide excision repair proteins UvrABC: importance of the Cr(III)-purine moiety in the enzymatic reaction Abs: Hexavalent chromium [Cr(VI)] is an ubiquitous environmental contaminant and a well-known etiological agent of human lung cancer. Inside human cells, Cr(VI) is reduced to Cr(III), which can conjugate with amino acids, ascorbic acids, and glutathiones in the cytoplasm. Conjugated and unconjugated Cr(III) can enter the nucleus to form adducts with DNA and electrostatically interact with the phosphate group of DNA. It has been found that in both human and Escherichia coli systems, Cr(III) ligand-conjugated DNA ternary adducts are efficiently repaired by the nucleotide excision repair (NER) pathway. In contrast, DNA adducts formed by unconjugated Cr(III) with DNA are repaired significantly less efficiently by the NER system. These results raise the possibility that the NER system repairs Cr(III) ligand-conjugated DNA adducts and biadducts such as Cr(III)-guanine-phosphate adducts but not Cr(III)-phosphate adducts. To test this hypothesis, we determined the cutting efficiency and the mode of cutting of DNA modified with tannin-conjugated Cr(III) by the E. coli NER enzymes UvrABC. Tannin compounds, gallic acid (GA), and ethyl gallate (EGA) can reduce Cr(VI) to Cr(III) to form Cr(III)-GA 2 and Cr(III)-EGA 2, respectively, which can interact with a single guanine or adenine base but not with the DNA phosphate backbone. We found that UvrABC is able to incise Cr(III)-GA 2- and Cr(III)-EGA 2-modified plasmid DNA, and the amount of incision increased as a function of tannin concentration used for modifications. In contrast, UvrABC nuclease does not incise GA- and EGA-modified plasmid DNA. Mapping the sequence specificity of Cr(III)-GA 2- and Cr(III)-EGA 2-DNA formation in the human p53 gene sequence by UvrABC nuclease cutting, we found that the sequence specificity for both adducts is the same but is much more selective than Cr(III)-guanine-DNA adducts. Together, these results suggest that NER proteins from E. coli recognize the purine-Cr(III) adduct but not the Cr(III)-backbone phosphate complex."
1509708,Srivastava et al. 2008,Removal of chromium (VI) through biosorption by the Pseudomonas spp. isolated from tannery effluent,"Heavy metal contamination of the rivers is a world wide environmental problem and its removal is a great challenge. Kanpur and Unnao two closely located districts of Uttar Pradesh India are known for their leather industries. The tanneries release their treated effluent in the near by water ways containing Cr metal that eventually merges with the river Ganges. Untreated tannery effluent contains 2.673 +/- 0.32 to 3.268 +/- 0.73 mg l(-1) Cr. Microbes were isolated, keeping the natural selection in the view, from the tannery effluent since microbes present in the effluent exposed to the various types of stresses and metal stress is one of them. Investigations include the exposure of higher concentrations of Cr(VI) 1.0 to 4.0 mg l(-1) to the bacteria (presumably the Pseudomonas spp.) predominant on the agar plate. The short termed study (72 h) of biosorption showed significant reduction of metal in the media especially in the higher concentrations with a value from 1.0 +/- 0.02, 2.0 +/- 0.01, 3.0 +/- 0, and 4.0 +/- 0.09 at zero h to 0.873 +/- 0.55, 1.840 +/- 1.31, 2.780 +/- 0.03 and 3.502 +/- 0.68 at 72 h respectively. The biosorption of metal show in the present study that the naturally occurring microbes have enough potential to mitigate the excessive contamination of their surroundings and can be used to reduce the metal concentrations in aqueous solutions in a specific time frame.","Removal of chromium (VI) through biosorption by the Pseudomonas spp. isolated from tannery effluent Abs: Heavy metal contamination of the rivers is a world wide environmental problem and its removal is a great challenge. Kanpur and Unnao two closely located districts of Uttar Pradesh India are known for their leather industries. The tanneries release their treated effluent in the near by water ways containing Cr metal that eventually merges with the river Ganges. Untreated tannery effluent contains 2.673 +/- 0.32 to 3.268 +/- 0.73 mg l(-1) Cr. Microbes were isolated, keeping the natural selection in the view, from the tannery effluent since microbes present in the effluent exposed to the various types of stresses and metal stress is one of them. Investigations include the exposure of higher concentrations of Cr(VI) 1.0 to 4.0 mg l(-1) to the bacteria (presumably the Pseudomonas spp.) predominant on the agar plate. The short termed study (72 h) of biosorption showed significant reduction of metal in the media especially in the higher concentrations with a value from 1.0 +/- 0.02, 2.0 +/- 0.01, 3.0 +/- 0, and 4.0 +/- 0.09 at zero h to 0.873 +/- 0.55, 1.840 +/- 1.31, 2.780 +/- 0.03 and 3.502 +/- 0.68 at 72 h respectively. The biosorption of metal show in the present study that the naturally occurring microbes have enough potential to mitigate the excessive contamination of their surroundings and can be used to reduce the metal concentrations in aqueous solutions in a specific time frame."
1509707,Mandiwana 2008,Rapid leaching of Cr(VI) in soil with Na3PO4 in the determination of hexavalent chromium by electrothermal atomic absorption spectrometry,"A method has been developed that leaches Cr(VI) selectively from soil samples. Hexavalent chromium was leached completely from soil with 0.01molL(-1) Na(3)PO(4). This was achieved by boiling the soil-reagent solution mixture for a period of 5min. The leached Cr(VI) was then quantified by electrothermal atomic absorption spectrometry (ET-AAS) after filtration of the sample solutions through Hydrophilic Millipore PVDF 0.45microm filter. Statistical evaluations indicated that the new developed method is reliable since neither its comparison with the established method nor the comparison of the sum of the concentrations of chromium species to that of the total concentration of chromium show any difference at 95% level of confidence. The spiking of soil samples with Cr(III) standards before pretreatment show that Cr(III) was not oxidized to Cr(VI) during leaching as the Cr(VI) content never increased. The detection limit established was 0.07microg g(-1), which is an improvement to that of the US EPA method 3060A by a factor of more than 500. The maximum concentrations of Cr(VI) found in soil samples collected around the new chromium mine was 8.0microg g(-1) and falls within acceptable level of 15microg g(-1) in accordance with the Italian Guidelines.","Rapid leaching of Cr(VI) in soil with Na3PO4 in the determination of hexavalent chromium by electrothermal atomic absorption spectrometry Abs: A method has been developed that leaches Cr(VI) selectively from soil samples. Hexavalent chromium was leached completely from soil with 0.01molL(-1) Na(3)PO(4). This was achieved by boiling the soil-reagent solution mixture for a period of 5min. The leached Cr(VI) was then quantified by electrothermal atomic absorption spectrometry (ET-AAS) after filtration of the sample solutions through Hydrophilic Millipore PVDF 0.45microm filter. Statistical evaluations indicated that the new developed method is reliable since neither its comparison with the established method nor the comparison of the sum of the concentrations of chromium species to that of the total concentration of chromium show any difference at 95% level of confidence. The spiking of soil samples with Cr(III) standards before pretreatment show that Cr(III) was not oxidized to Cr(VI) during leaching as the Cr(VI) content never increased. The detection limit established was 0.07microg g(-1), which is an improvement to that of the US EPA method 3060A by a factor of more than 500. The maximum concentrations of Cr(VI) found in soil samples collected around the new chromium mine was 8.0microg g(-1) and falls within acceptable level of 15microg g(-1) in accordance with the Italian Guidelines."
1509706,Wang et al. 2009,Removal of chromium (VI) from aqueous solution using walnut hull,"In this study, removal of chromium (VI) from aqueous solution by walnut hull (a local low-cost adsorbent) was studied. The extent of adsorption was investigated as a function of solution pH, contact time, adsorbent and adsorbate concentration, reaction temperature and supporting electrolyte (sodium chloride). The Cr (VI) removal was pH-dependent, reaching a maximum (97.3%) at pH 1.0. The kinetic experimental data were fitted to the first-order, modified Freundlich, intraparticle diffusion and Elovich models and the corresponding parameters were obtained. A 102.78 kJ/mol Ea (activation energy) for the reaction of chromium (VI) adsorption onto walnut indicated that the rate-limiting step in this case might be a chemically controlled process. Both the Langmuir and Freundlich isotherms were suitable for describing the biosorption of chromium (VI) onto walnut hull. The uptake of chromium (VI) per weight of adsorbent increased with increasing initial chromium (VI) concentration up to 240-480 mg/L, and decreased sharply with increasing adsorbent concentration ranging from 1.0 to 5.0 g/L. An increase in sodium chloride (as supporting electrolyte) concentration was found to induce a negative effect while an increase in temperature was found to give rise to a positive effect on the chromium (VI) adsorption process. Compared to the various other adsorbents reported in the literature, the walnut hull in this study shows very good promise for practical applicability.","Removal of chromium (VI) from aqueous solution using walnut hull Abs: In this study, removal of chromium (VI) from aqueous solution by walnut hull (a local low-cost adsorbent) was studied. The extent of adsorption was investigated as a function of solution pH, contact time, adsorbent and adsorbate concentration, reaction temperature and supporting electrolyte (sodium chloride). The Cr (VI) removal was pH-dependent, reaching a maximum (97.3%) at pH 1.0. The kinetic experimental data were fitted to the first-order, modified Freundlich, intraparticle diffusion and Elovich models and the corresponding parameters were obtained. A 102.78 kJ/mol Ea (activation energy) for the reaction of chromium (VI) adsorption onto walnut indicated that the rate-limiting step in this case might be a chemically controlled process. Both the Langmuir and Freundlich isotherms were suitable for describing the biosorption of chromium (VI) onto walnut hull. The uptake of chromium (VI) per weight of adsorbent increased with increasing initial chromium (VI) concentration up to 240-480 mg/L, and decreased sharply with increasing adsorbent concentration ranging from 1.0 to 5.0 g/L. An increase in sodium chloride (as supporting electrolyte) concentration was found to induce a negative effect while an increase in temperature was found to give rise to a positive effect on the chromium (VI) adsorption process. Compared to the various other adsorbents reported in the literature, the walnut hull in this study shows very good promise for practical applicability."
1509705,Ouejhani et al. 2008,Application of Doehlert matrix to the study of electrochemical oxidation of Cr(III) to Cr(VI) in order to recover chromium from wastewater tanning baths,"The aim of this study was to optimize simultaneously the chemical and faradic yields of electrochemical oxidation of chromium(III) to chromium(VI) over a titanium-platinum anode in order to recover trivalent chromium from aqueous and tanning baths effluent. A Doehlert design was used to optimize the significant experimental variables: concentration of chloride ions [Cl(-)] (mol L(-1)); temperature of reactional media T (degrees C); pH of reactional media; intensity of electrolysis current I (A); time of electrolysis t(h). The quadratic models of second degree relate chemical (R(C)) and faradic (R(F)) yields to the different variables affecting the electrochemical reaction were determined by the NEMROD software program. Having to study simultaneously two responses, the Pareto graphic analysis of effects was used. The results obtained in this study have shown that the current intensity and the electrolysis time were the main influent parameters on the removal ratio of chemical oxygen demand (COD), total organic carbon (TOC) and electrochemical oxidation of trivalent chromium.","Application of Doehlert matrix to the study of electrochemical oxidation of Cr(III) to Cr(VI) in order to recover chromium from wastewater tanning baths Abs: The aim of this study was to optimize simultaneously the chemical and faradic yields of electrochemical oxidation of chromium(III) to chromium(VI) over a titanium-platinum anode in order to recover trivalent chromium from aqueous and tanning baths effluent. A Doehlert design was used to optimize the significant experimental variables: concentration of chloride ions [Cl(-)] (mol L(-1)); temperature of reactional media T (degrees C); pH of reactional media; intensity of electrolysis current I (A); time of electrolysis t(h). The quadratic models of second degree relate chemical (R(C)) and faradic (R(F)) yields to the different variables affecting the electrochemical reaction were determined by the NEMROD software program. Having to study simultaneously two responses, the Pareto graphic analysis of effects was used. The results obtained in this study have shown that the current intensity and the electrolysis time were the main influent parameters on the removal ratio of chemical oxygen demand (COD), total organic carbon (TOC) and electrochemical oxidation of trivalent chromium."
1509704,Desai et al. 2008,Evaluation of in vitro Cr(VI) reduction potential in cytosolic extracts of three indigenous Bacillus sp. isolated from Cr(VI) polluted industrial landfill,"Three efficient Cr(VI) reducing bacterial strains were isolated from Cr(VI) polluted landfill and characterized for in vitro Cr(VI) reduction. Phylogenetic analysis using 16S rRNA gene sequencing revealed that the newly isolated strains G1DM20, G1DM22 and G1DM64 were closely related to Bacillus cereus, Bacillus fusiformis and Bacillus sphaericus, respectively. The suspended cultures of all Bacillus sp. exhibited more than 85% reduction of 1000 microM Cr(VI) within 30 h. The suspended culture of Bacillus sp. G1DM22 exhibited an ability for continuous reduction of 100 microM Cr(VI) up to seven consecutive inputs. Assays with the permeabilized cells and cell-free extracts from each of Bacillus sp. demonstrated that the hexavalent chromate reductase activity was mainly associated with the soluble fraction of cells and expressed constitutively. The Cr(VI) reduction by the cell-free extracts of Bacillus sp. G1DM20 and G1DM22 was maximum at 30 degrees C and pH 7 whereas, Bacillus sp. G1DM64 exhibited maximum Cr(VI) reduction at pH 6. Addition of 1mM NADH enhanced the Cr(VI) reductase activity in the cell-free extracts of all three isolates. Amongst all three isolates tested, crude cell-free extracts of Bacillus sp. G1DM22 exhibited the fastest Cr(VI) reduction rate with complete reduction of 100 microM Cr(VI) within 100 min. The apparent K(m) and V(max) of the chromate reductase activity in Bacillus sp. G1DM22 were determined to be 200 microM Cr(VI) and 5.5 micromol/min/mg protein, respectively. The Cr(VI) reductase activity in cell-free extracts of all the isolates was stable in presence of different metal ions tested except Hg(2+) and Ag(+).","Evaluation of in vitro Cr(VI) reduction potential in cytosolic extracts of three indigenous Bacillus sp. isolated from Cr(VI) polluted industrial landfill Abs: Three efficient Cr(VI) reducing bacterial strains were isolated from Cr(VI) polluted landfill and characterized for in vitro Cr(VI) reduction. Phylogenetic analysis using 16S rRNA gene sequencing revealed that the newly isolated strains G1DM20, G1DM22 and G1DM64 were closely related to Bacillus cereus, Bacillus fusiformis and Bacillus sphaericus, respectively. The suspended cultures of all Bacillus sp. exhibited more than 85% reduction of 1000 microM Cr(VI) within 30 h. The suspended culture of Bacillus sp. G1DM22 exhibited an ability for continuous reduction of 100 microM Cr(VI) up to seven consecutive inputs. Assays with the permeabilized cells and cell-free extracts from each of Bacillus sp. demonstrated that the hexavalent chromate reductase activity was mainly associated with the soluble fraction of cells and expressed constitutively. The Cr(VI) reduction by the cell-free extracts of Bacillus sp. G1DM20 and G1DM22 was maximum at 30 degrees C and pH 7 whereas, Bacillus sp. G1DM64 exhibited maximum Cr(VI) reduction at pH 6. Addition of 1mM NADH enhanced the Cr(VI) reductase activity in the cell-free extracts of all three isolates. Amongst all three isolates tested, crude cell-free extracts of Bacillus sp. G1DM22 exhibited the fastest Cr(VI) reduction rate with complete reduction of 100 microM Cr(VI) within 100 min. The apparent K(m) and V(max) of the chromate reductase activity in Bacillus sp. G1DM22 were determined to be 200 microM Cr(VI) and 5.5 micromol/min/mg protein, respectively. The Cr(VI) reductase activity in cell-free extracts of all the isolates was stable in presence of different metal ions tested except Hg(2+) and Ag(+)."
1509703,Rozhon et al. 2008,Rapid quantification of global DNA methylation by isocratic cation exchange high-performance liquid chromatography,"The DNA of many eukaryotes is methylated at specific cytosine residues in connection with gene regulation. Here we report a method for the quantification of global cytosine methylation based on enzymatic hydrolysis of DNA, dephosphorylation, and subsequent high-performance cation exchange chromatography. Nucleosides are separated in less than 3 min under isocratic conditions on a benzenesulfonic acid-modified silica phase and detected by UV absorption. As little as 1 microg of DNA is sufficient to measure 5-methyldeoxycytosine levels with a typical relative standard deviation of less than 3%. As a proof of concept, the method was applied for analysis of DNA from several Arabidopsis thaliana mutants affected in DNA methylation and from Medicago sativa seedlings treated with the environmental pollutant chromium(VI).","Rapid quantification of global DNA methylation by isocratic cation exchange high-performance liquid chromatography Abs: The DNA of many eukaryotes is methylated at specific cytosine residues in connection with gene regulation. Here we report a method for the quantification of global cytosine methylation based on enzymatic hydrolysis of DNA, dephosphorylation, and subsequent high-performance cation exchange chromatography. Nucleosides are separated in less than 3 min under isocratic conditions on a benzenesulfonic acid-modified silica phase and detected by UV absorption. As little as 1 microg of DNA is sufficient to measure 5-methyldeoxycytosine levels with a typical relative standard deviation of less than 3%. As a proof of concept, the method was applied for analysis of DNA from several Arabidopsis thaliana mutants affected in DNA methylation and from Medicago sativa seedlings treated with the environmental pollutant chromium(VI)."
1509702,Iordache et al. 2008,Electrochemically driven intramolecular ring closure of a linear hexapyrrole,"[24]hexaphyrin(1.0.1.0.0.0) was electrochemically synthesized in good yield starting from a linear hexapyrrolic precursor. This straightforward approach provides an efficient &quot;green&quot; alternative to the reported chemical synthesis, which requires the use of trifluoroacetic acid as the solvent and toxic chromium(VI) salts as the oxidant.","Electrochemically driven intramolecular ring closure of a linear hexapyrrole Abs: [24]hexaphyrin(1.0.1.0.0.0) was electrochemically synthesized in good yield starting from a linear hexapyrrolic precursor. This straightforward approach provides an efficient &quot;green&quot; alternative to the reported chemical synthesis, which requires the use of trifluoroacetic acid as the solvent and toxic chromium(VI) salts as the oxidant."
1509701,Carriquiriborde and  Ronco 2008,"Distinctive accumulation patterns of Cd(II), Cu(II), and Cr(VI) in tissue of the South American teleost, pejerrey (Odontesthes bonariensis)","The time- and concentration-dependent accumulation patterns of three environmentally relevant metals, with different chemical and biological properties, were comparatively evaluated in tissue of South American fish, pejerrey (Odontesthes bonariensis). Six-month-old juvenile pejerrey were exposed to 1, 5, or 10 microgl(-1) of Cd(2+); 10, 50, or 100 microgl(-1) of Cu(2+); or 100, 500, or 1000 microgl(-1) of Cr(6+) during 16 days. Tested concentrations ranged from those that caused no significant accumulation to those that induced growth reduction or even mortality (Cd and Cu). Concentration-dependent accumulation of Cd and Cr presented similar patterns, characterized by a linear and exponential relationship in the gill and liver, respectively, with a greater slope at longer exposure times. Differently, essential Cu showed a linear relationship in both tissues, and no slope increase was observed in the gill. The gill time-dependent accumulation pattern of Cd exhibited relatively long times to half-saturation (t(1/2(1))=36.6 days) and high-saturation values (S((1))=205.4 nmolg(-1)). The opposite pattern was observed for Cu (t(1/2(100))=0.6 days; S((100))=24.4 nmolg(-1)), while Cr showed an intermediate position (t(1/2(1000))=2.8 days; S((1000))=50.2 nmolg(-1)). In the liver, times to half saturation for the three metals were as follows: Cd=4.7 days; Cu=2.5 days; Cr=1.6 days. Conversely, different saturation concentrations were observed among metals, Cu (S((100))=102) presenting the highest values, Cd (S((10))=4.4) the lowest, and Cr presenting an intermediate position (S((1000))=24.7). Bioconcentration of non-essential Cd was high in the gill (2000-fold) and low in the liver (50-fold). On the other hand, the essential element Cu was poorly retained by the gill (15-fold) and accumulated mainly in the liver (50-fold). Differently, Cr was quickly and evenly accumulated by both organs, but barely bioconcentrating (2.5- and 1.5-fold levels as compared to the original in the gill and liver, respectively). The ratio of gill/liver concentration in exposed fish clearly differed from that of non-exposed fish, and was characteristic for each metal (Cd&gt;1; Cu&lt;1; Cr&lt;9), representing a potential tool to assess exposure. The accumulation patterns of studied metals in the tissue of pejerrey corresponded more with those reported for sensitive than for tolerant fish species. Distinctive tissue accumulation patterns in relation to growth reduction and non-acute lethality suggests different target tissues for sub-chronic effects, and would partially explain differences in the relative toxicity of these metals.","Distinctive accumulation patterns of Cd(II), Cu(II), and Cr(VI) in tissue of the South American teleost, pejerrey (Odontesthes bonariensis) Abs: The time- and concentration-dependent accumulation patterns of three environmentally relevant metals, with different chemical and biological properties, were comparatively evaluated in tissue of South American fish, pejerrey (Odontesthes bonariensis). Six-month-old juvenile pejerrey were exposed to 1, 5, or 10 microgl(-1) of Cd(2+); 10, 50, or 100 microgl(-1) of Cu(2+); or 100, 500, or 1000 microgl(-1) of Cr(6+) during 16 days. Tested concentrations ranged from those that caused no significant accumulation to those that induced growth reduction or even mortality (Cd and Cu). Concentration-dependent accumulation of Cd and Cr presented similar patterns, characterized by a linear and exponential relationship in the gill and liver, respectively, with a greater slope at longer exposure times. Differently, essential Cu showed a linear relationship in both tissues, and no slope increase was observed in the gill. The gill time-dependent accumulation pattern of Cd exhibited relatively long times to half-saturation (t(1/2(1))=36.6 days) and high-saturation values (S((1))=205.4 nmolg(-1)). The opposite pattern was observed for Cu (t(1/2(100))=0.6 days; S((100))=24.4 nmolg(-1)), while Cr showed an intermediate position (t(1/2(1000))=2.8 days; S((1000))=50.2 nmolg(-1)). In the liver, times to half saturation for the three metals were as follows: Cd=4.7 days; Cu=2.5 days; Cr=1.6 days. Conversely, different saturation concentrations were observed among metals, Cu (S((100))=102) presenting the highest values, Cd (S((10))=4.4) the lowest, and Cr presenting an intermediate position (S((1000))=24.7). Bioconcentration of non-essential Cd was high in the gill (2000-fold) and low in the liver (50-fold). On the other hand, the essential element Cu was poorly retained by the gill (15-fold) and accumulated mainly in the liver (50-fold). Differently, Cr was quickly and evenly accumulated by both organs, but barely bioconcentrating (2.5- and 1.5-fold levels as compared to the original in the gill and liver, respectively). The ratio of gill/liver concentration in exposed fish clearly differed from that of non-exposed fish, and was characteristic for each metal (Cd&gt;1; Cu&lt;1; Cr&lt;9), representing a potential tool to assess exposure. The accumulation patterns of studied metals in the tissue of pejerrey corresponded more with those reported for sensitive than for tolerant fish species. Distinctive tissue accumulation patterns in relation to growth reduction and non-acute lethality suggests different target tissues for sub-chronic effects, and would partially explain differences in the relative toxicity of these metals."
1509700,Grabarczyk 2008,A catalytic adsorptive stripping voltammetric procedure for trace determination of Cr(VI) in natural samples containing high concentrations of humic substances,"A simple and fast catalytic adsorptive stripping voltammetric procedure for trace determination of Cr(VI) in natural samples containing high concentrations of humic substances has been developed. The procedure for chromium determination in the presence of DTPA and nitrates was employed as the initial method. In order to enhance the selectivity vs. Cr(III) the measurements were performed at 40 degrees C. Interference from dissolved organic matter such as humic and fulvic acids was drastically decreased by adding Amberlite XAD-7 resin to the voltammetric cell before the deaeration step. The whole procedure was applied to a single cell, which allowed monitoring of the voltammetric scan. Optimum conditions for removing humic and fulvic acids due to their adsorption on XAD-7 resin were evaluated. The use of XAD-7 resin also minimize interferences from various cationic, anionic, and nonionic surfactants. The calibration graph for Cr(VI) for an accumulation time of 30 s was linear in the range 5 x 10(-10) to 5 x 10(-8) mol L(-1). The relative standard deviation for determination of Cr(VI) at a concentration of 1 x 10(-8) mol L(-1) was 3.5% (n = 5). The detection limit estimated from 3 times the standard deviation for low Cr(VI) concentrations and an accumulation time of 30 s was about 1.3 x 10(-10) mol L(-1). The proposed method was successfully applied to Cr(VI) determination at trace levels in soil samples.","A catalytic adsorptive stripping voltammetric procedure for trace determination of Cr(VI) in natural samples containing high concentrations of humic substances Abs: A simple and fast catalytic adsorptive stripping voltammetric procedure for trace determination of Cr(VI) in natural samples containing high concentrations of humic substances has been developed. The procedure for chromium determination in the presence of DTPA and nitrates was employed as the initial method. In order to enhance the selectivity vs. Cr(III) the measurements were performed at 40 degrees C. Interference from dissolved organic matter such as humic and fulvic acids was drastically decreased by adding Amberlite XAD-7 resin to the voltammetric cell before the deaeration step. The whole procedure was applied to a single cell, which allowed monitoring of the voltammetric scan. Optimum conditions for removing humic and fulvic acids due to their adsorption on XAD-7 resin were evaluated. The use of XAD-7 resin also minimize interferences from various cationic, anionic, and nonionic surfactants. The calibration graph for Cr(VI) for an accumulation time of 30 s was linear in the range 5 x 10(-10) to 5 x 10(-8) mol L(-1). The relative standard deviation for determination of Cr(VI) at a concentration of 1 x 10(-8) mol L(-1) was 3.5% (n = 5). The detection limit estimated from 3 times the standard deviation for low Cr(VI) concentrations and an accumulation time of 30 s was about 1.3 x 10(-10) mol L(-1). The proposed method was successfully applied to Cr(VI) determination at trace levels in soil samples."
1509699,Opperman and  van Heerden 2007,Aerobic Cr(VI) reduction by Thermus scotoductus strain SA-01,"<strong>AIM: </strong>To evaluate Thermus scotoductus SA-01's ability to reduce Cr(VI) aerobically.<br /><br /><strong>METHODS AND RESULTS: </strong>T. scotoductus SA-01 is able to reduce Cr(VI) aerobically when grown in a complex organic medium containing Cr(VI) concentrations up to 0.5 mmol l(-1). Suspension of T. scotoductus SA-01 cells also reduced Cr(VI) aerobically under nongrowth conditions using a variety of electron donors as well as in the absence of an exogenous electron donor. The optimum temperature and pH for Cr(VI) reduction under nongrowth conditions were found to be 80 degrees C and 7, respectively. It was also found that the Cr(VI) reduction was catalysed by a cytoplasmic, constitutively expressed enzyme.<br /><br /><strong>CONCLUSIONS: </strong>Apart from SA-01's ability to reduce Cr(VI) through a strictly anaerobic membrane-bound mechanism (unpublished data), it also has a second enzyme localized in the cytoplasm that can reduce Cr(VI) aerobically. As this enzyme is constitutively expressed and not induced by Cr(VI), it remains to be determined whether it has any other physiological functions.<br /><br /><strong>SIGNIFICANCE AND IMPACT OF THE STUDY: </strong>This is the first report of a Thermus species able to reduce Cr(VI) aerobically and extends the knowledge of parameters associated with Cr(VI) reduction. Employing thermophiles in bioremediation using industrial bioreactors would cancel the need for expensive cooling systems.","Aerobic Cr(VI) reduction by Thermus scotoductus strain SA-01 Abs: <strong>AIM: </strong>To evaluate Thermus scotoductus SA-01's ability to reduce Cr(VI) aerobically.<br /><br /><strong>METHODS AND RESULTS: </strong>T. scotoductus SA-01 is able to reduce Cr(VI) aerobically when grown in a complex organic medium containing Cr(VI) concentrations up to 0.5 mmol l(-1). Suspension of T. scotoductus SA-01 cells also reduced Cr(VI) aerobically under nongrowth conditions using a variety of electron donors as well as in the absence of an exogenous electron donor. The optimum temperature and pH for Cr(VI) reduction under nongrowth conditions were found to be 80 degrees C and 7, respectively. It was also found that the Cr(VI) reduction was catalysed by a cytoplasmic, constitutively expressed enzyme.<br /><br /><strong>CONCLUSIONS: </strong>Apart from SA-01's ability to reduce Cr(VI) through a strictly anaerobic membrane-bound mechanism (unpublished data), it also has a second enzyme localized in the cytoplasm that can reduce Cr(VI) aerobically. As this enzyme is constitutively expressed and not induced by Cr(VI), it remains to be determined whether it has any other physiological functions.<br /><br /><strong>SIGNIFICANCE AND IMPACT OF THE STUDY: </strong>This is the first report of a Thermus species able to reduce Cr(VI) aerobically and extends the knowledge of parameters associated with Cr(VI) reduction. Employing thermophiles in bioremediation using industrial bioreactors would cancel the need for expensive cooling systems."
1509697,Ramírez-Díaz et al. 2008,Mechanisms of bacterial resistance to chromium compounds,"Chromium is a non-essential and well-known toxic metal for microorganisms and plants. The widespread industrial use of this heavy metal has caused it to be considered as a serious environmental pollutant. Chromium exists in nature as two main species, the trivalent form, Cr(III), which is relatively innocuous, and the hexavalent form, Cr(VI), considered a more toxic species. At the intracellular level, however, Cr(III) seems to be responsible for most toxic effects of chromium. Cr(VI) is usually present as the oxyanion chromate. Inhibition of sulfate membrane transport and oxidative damage to biomolecules are associated with the toxic effects of chromate in bacteria. Several bacterial mechanisms of resistance to chromate have been reported. The best characterized mechanisms comprise efflux of chromate ions from the cell cytoplasm and reduction of Cr(VI) to Cr(III). Chromate efflux by the ChrA transporter has been established in Pseudomonas aeruginosa and Cupriavidus metallidurans (formerly Alcaligenes eutrophus) and consists of an energy-dependent process driven by the membrane potential. The CHR protein family, which includes putative ChrA orthologs, currently contains about 135 sequences from all three domains of life. Chromate reduction is carried out by chromate reductases from diverse bacterial species generating Cr(III) that may be detoxified by other mechanisms. Most characterized enzymes belong to the widespread NAD(P)H-dependent flavoprotein family of reductases. Several examples of bacterial systems protecting from the oxidative stress caused by chromate have been described. Other mechanisms of bacterial resistance to chromate involve the expression of components of the machinery for repair of DNA damage, and systems related to the homeostasis of iron and sulfur.","Mechanisms of bacterial resistance to chromium compounds Abs: Chromium is a non-essential and well-known toxic metal for microorganisms and plants. The widespread industrial use of this heavy metal has caused it to be considered as a serious environmental pollutant. Chromium exists in nature as two main species, the trivalent form, Cr(III), which is relatively innocuous, and the hexavalent form, Cr(VI), considered a more toxic species. At the intracellular level, however, Cr(III) seems to be responsible for most toxic effects of chromium. Cr(VI) is usually present as the oxyanion chromate. Inhibition of sulfate membrane transport and oxidative damage to biomolecules are associated with the toxic effects of chromate in bacteria. Several bacterial mechanisms of resistance to chromate have been reported. The best characterized mechanisms comprise efflux of chromate ions from the cell cytoplasm and reduction of Cr(VI) to Cr(III). Chromate efflux by the ChrA transporter has been established in Pseudomonas aeruginosa and Cupriavidus metallidurans (formerly Alcaligenes eutrophus) and consists of an energy-dependent process driven by the membrane potential. The CHR protein family, which includes putative ChrA orthologs, currently contains about 135 sequences from all three domains of life. Chromate reduction is carried out by chromate reductases from diverse bacterial species generating Cr(III) that may be detoxified by other mechanisms. Most characterized enzymes belong to the widespread NAD(P)H-dependent flavoprotein family of reductases. Several examples of bacterial systems protecting from the oxidative stress caused by chromate have been described. Other mechanisms of bacterial resistance to chromate involve the expression of components of the machinery for repair of DNA damage, and systems related to the homeostasis of iron and sulfur."
1509696,Gokhale et al. 2008,Kinetic and equilibrium modeling of chromium (VI) biosorption on fresh and spent Spirulina platensis/Chlorella vulgaris biomass,"Biosorption of chromium (VI) was studied using both fresh and spent algal biomass of Spirulina platensis and Chlorella vulgaris. Both showed comparable behavior suggesting that biosorption is primarily a surface phenomenon. Biosorption rate was very fast during the first five minutes, in which almost 50% of the chromium (VI) was adsorbed. Two step kinetic model was proposed for biosorption. Equilibrium data obeyed Freundlich and Langmuir adsorption isotherms. Fresh algal biomass of S. platensis gave maximum of 73.6% biosorption of chromium (VI) in 100 ppm solution at 1 g l(-1) cell loading. For improved economics, beta-carotene was extracted from S. platensis and the spent biomass was used for chromium (VI) biosorption. The maximum biosorption by spent biomass was increased to 86.2%. Thus, this two step process not only showed improved efficiency in biosorption ( approximately 17% increase) but also gave valuable byproduct, namely beta-carotene.","Kinetic and equilibrium modeling of chromium (VI) biosorption on fresh and spent Spirulina platensis/Chlorella vulgaris biomass Abs: Biosorption of chromium (VI) was studied using both fresh and spent algal biomass of Spirulina platensis and Chlorella vulgaris. Both showed comparable behavior suggesting that biosorption is primarily a surface phenomenon. Biosorption rate was very fast during the first five minutes, in which almost 50% of the chromium (VI) was adsorbed. Two step kinetic model was proposed for biosorption. Equilibrium data obeyed Freundlich and Langmuir adsorption isotherms. Fresh algal biomass of S. platensis gave maximum of 73.6% biosorption of chromium (VI) in 100 ppm solution at 1 g l(-1) cell loading. For improved economics, beta-carotene was extracted from S. platensis and the spent biomass was used for chromium (VI) biosorption. The maximum biosorption by spent biomass was increased to 86.2%. Thus, this two step process not only showed improved efficiency in biosorption ( approximately 17% increase) but also gave valuable byproduct, namely beta-carotene."
1509693,Bishnoi et al. 2007,Biosorption of Cr (VI) with Trichoderma viride immobilized fungal biomass and cell free Ca-alginate beads,"Ability of Cr (VI) biosorption with immobilized Trichoderma viride biomass and cell free Ca-alginate beads was studied in the present study. Biosorption efficiency in the powdered fungal biomass entrapped in polymeric matric of calcium alginate compared with cell free calcium alginate beads. Effect of pH, initial metal ion concentration, time and biomass dose on the Cr (VI) removal by immobilized and cell free Ca-alginate beads were also determined. Biosorption of Cr (VI) was pH dependent and the maximum adsorption was observed at pH 2.0. The adsorption equilibrium was reached in 90 min. The maximum adsorption capacity of 16.075 mgg(-1) was observed at dose 0.2 mg in 100 ml of Cr (VI) solution. The high value of kinetics rate constant Kad (3.73 x 10(-2)) with immobilized fungal biomass and (3.75 x 10(-2)) with cell free Ca- alginate beads showed that the sorption of Cr (VI) ions on immobilized biomass and cell free Ca-alginate beads followed pseudo first order kinetics. The experimental results were fitted satisfactory to the Langmuir and Freundlich isotherm models. The hydroxyl (-OH) and amino (-NH) functional groups were responsible in biosorption of Cr (VI) with fungal biomass spp. Trichoderma viride analysed using Fourier Transform Infrared (FTIR) Spectrometer.","Biosorption of Cr (VI) with Trichoderma viride immobilized fungal biomass and cell free Ca-alginate beads Abs: Ability of Cr (VI) biosorption with immobilized Trichoderma viride biomass and cell free Ca-alginate beads was studied in the present study. Biosorption efficiency in the powdered fungal biomass entrapped in polymeric matric of calcium alginate compared with cell free calcium alginate beads. Effect of pH, initial metal ion concentration, time and biomass dose on the Cr (VI) removal by immobilized and cell free Ca-alginate beads were also determined. Biosorption of Cr (VI) was pH dependent and the maximum adsorption was observed at pH 2.0. The adsorption equilibrium was reached in 90 min. The maximum adsorption capacity of 16.075 mgg(-1) was observed at dose 0.2 mg in 100 ml of Cr (VI) solution. The high value of kinetics rate constant Kad (3.73 x 10(-2)) with immobilized fungal biomass and (3.75 x 10(-2)) with cell free Ca- alginate beads showed that the sorption of Cr (VI) ions on immobilized biomass and cell free Ca-alginate beads followed pseudo first order kinetics. The experimental results were fitted satisfactory to the Langmuir and Freundlich isotherm models. The hydroxyl (-OH) and amino (-NH) functional groups were responsible in biosorption of Cr (VI) with fungal biomass spp. Trichoderma viride analysed using Fourier Transform Infrared (FTIR) Spectrometer."
1509692,Carrington et al. 2006,Electrochemical deposition of sol-gel films for enhanced chromium(VI) determination in aqueous solutions,"A pyridine-functionalized sol-gel film has been formed by electrodeposition at a glassy carbon electrode surface. When this protonated film is exposed to a Cr(VI) solution, the Cr(VI) anions are preconcentrated at the electrode surface. Using square wave voltammetry, the Cr(VI) species are reduced to Cr(III), and a peak current corresponding to this reduction is generated at 0.17V. The peak currents can be correlated with the Cr(VI) concentration. The functionalized sol-gel films demonstrated an enhanced sensitivity for Cr(VI) in aqueous solutions, providing a limit of detection at the low ppb level. Interference studies also displayed the high selectivity of the films for Cr(VI), and the system was able to tolerate a large excess of Cr(III) with no adverse affects. The reported electrodeposition method of film formation uses commercially available reagents and yields films quickly and reproducibly. The growth of these sol-gel films was monitored using an electrochemical quartz crystal microbalance (EQCM), and they were characterized by X-ray photoelectron spectroscopy (XPS) and scanning electron microscopy (SEM). The reported work shows the promise of such an electrode for use in Cr(VI) sensing applications.","Electrochemical deposition of sol-gel films for enhanced chromium(VI) determination in aqueous solutions Abs: A pyridine-functionalized sol-gel film has been formed by electrodeposition at a glassy carbon electrode surface. When this protonated film is exposed to a Cr(VI) solution, the Cr(VI) anions are preconcentrated at the electrode surface. Using square wave voltammetry, the Cr(VI) species are reduced to Cr(III), and a peak current corresponding to this reduction is generated at 0.17V. The peak currents can be correlated with the Cr(VI) concentration. The functionalized sol-gel films demonstrated an enhanced sensitivity for Cr(VI) in aqueous solutions, providing a limit of detection at the low ppb level. Interference studies also displayed the high selectivity of the films for Cr(VI), and the system was able to tolerate a large excess of Cr(III) with no adverse affects. The reported electrodeposition method of film formation uses commercially available reagents and yields films quickly and reproducibly. The growth of these sol-gel films was monitored using an electrochemical quartz crystal microbalance (EQCM), and they were characterized by X-ray photoelectron spectroscopy (XPS) and scanning electron microscopy (SEM). The reported work shows the promise of such an electrode for use in Cr(VI) sensing applications."
1509691,Rajesh et al. 2008,Solid phase extraction of chromium(VI) from aqueous solutions by adsorption of its diphenylcarbazide complex on a mixed bed adsorbent (acid activated montmorillonite-silica gel) column,"A novel approach has been developed for the solid phase extraction of chromium(VI) based on the adsorption of its diphenylcarbazide complex on a mixture of acid activated montmorillonite (AAM)-silica gel column. The effect of various parameters such as acidity, stability of the column, sample volume, interfering ions, etc., were studied in detail. The adsorbed complex could be easily eluted using polyethylene glycol-sulfuric acid mixture and the concentration of chromium has been determined using visible spectrophotometry. The calibration graph was linear in the range 0-1microgmL(-1) chromium(VI) with a detection limit of 6microgL(-1). A highest preconcentration factor of 25 could be obtained for 250mL sample volume using glass wool as support for the mixed bed adsorbent. Chromium(VI) could be effectively separated from other ions such as nickel, copper, zinc, chloride, sulfate, nitrate, etc., and the method has been successfully applied to study the recovery of chromium in electroplating waste water and spiked water samples.","Solid phase extraction of chromium(VI) from aqueous solutions by adsorption of its diphenylcarbazide complex on a mixed bed adsorbent (acid activated montmorillonite-silica gel) column Abs: A novel approach has been developed for the solid phase extraction of chromium(VI) based on the adsorption of its diphenylcarbazide complex on a mixture of acid activated montmorillonite (AAM)-silica gel column. The effect of various parameters such as acidity, stability of the column, sample volume, interfering ions, etc., were studied in detail. The adsorbed complex could be easily eluted using polyethylene glycol-sulfuric acid mixture and the concentration of chromium has been determined using visible spectrophotometry. The calibration graph was linear in the range 0-1microgmL(-1) chromium(VI) with a detection limit of 6microgL(-1). A highest preconcentration factor of 25 could be obtained for 250mL sample volume using glass wool as support for the mixed bed adsorbent. Chromium(VI) could be effectively separated from other ions such as nickel, copper, zinc, chloride, sulfate, nitrate, etc., and the method has been successfully applied to study the recovery of chromium in electroplating waste water and spiked water samples."
1509690,Han et al. 2007,Determination of chromium(VI) by surface plasmon field-enhanced resonance light scattering,"A surface plasmon-enhanced resonance light scattering method has been developed. The method features strong light scattering but very weak background, and after incorporating with selective sample extraction and ion-association complexation using rhodamine B and KI as reactants, it could selectively determine Cr(VI) in both of standard and real samples, reaching a limit of detection down to 20 nM which is about 40-fold as sensitive as flame atomic absorption spectrometry and 140-fold as sensitive as fluorescent spectroscopy. Its linear working range was found in between 40 and 320 nM, with a relative standard deviation of peak height at &lt;3% (n = 5) and recovery between 94.8-104.9%. In theory, the method is applicable to the analysis of all substances able to produce or destroy I2.","Determination of chromium(VI) by surface plasmon field-enhanced resonance light scattering Abs: A surface plasmon-enhanced resonance light scattering method has been developed. The method features strong light scattering but very weak background, and after incorporating with selective sample extraction and ion-association complexation using rhodamine B and KI as reactants, it could selectively determine Cr(VI) in both of standard and real samples, reaching a limit of detection down to 20 nM which is about 40-fold as sensitive as flame atomic absorption spectrometry and 140-fold as sensitive as fluorescent spectroscopy. Its linear working range was found in between 40 and 320 nM, with a relative standard deviation of peak height at &lt;3% (n = 5) and recovery between 94.8-104.9%. In theory, the method is applicable to the analysis of all substances able to produce or destroy I2."
1509689,Ramoliya et al. 2007,Movement and bioaccumulation of chromium in an artificial freshwater ecosystem,"In the present study, a small fresh water aquatic ecosystem was created into a small test tank to evaluate the movement and bioaccumulation of Cr (VI) through water, sediment, a macrophyte Hydrilla, small fish guppy, and few key organs of magur, Clarias batrachus. The Cr (VI) intoxication was imposed of as a single dose of 30 mg/l concentration for a wide range of exposure durations like 1, 7, 14 and 21 days. After 1 day of exposure the total Cr (VI) load was very high in the water and sediment samples (5.187 microg/ml and 23.332 microg/g respectively) which were decreased with increasing exposure durations over their respective controls. In samples of macrophyte, Cr (VI) concentration showed a gradual increasing trend from 6.1797 microg/g in control to 21.1903 microg/g in 1 day exposure and reached up to 24.635 microg/g after 21 days exposure. In guppy, the Cr (VI) bioaccumulation showed an increasing trend but the rate was not statistically significant. However, in magur, the Cr (VI) uptake showed a significant gradual and increasing trend with increasing exposure durations in liver, brain, intestine and muscular tissues than gill and kidney over their respective controls. The movement of the Cr (VI) was found to be from sediment to water during pre-treatment phase, after intoxication, from water to macrophyte and to other phytoplankton and zooplankton. It then accumulated in the primary consumer guppy and finally moved to the secondary consumer the magur following the food web. The results reveal that the rate of movement and bioaccumulation of Cr (VI) varied from organism to organism and in C. batrachus, from tissue to tissue.","Movement and bioaccumulation of chromium in an artificial freshwater ecosystem Abs: In the present study, a small fresh water aquatic ecosystem was created into a small test tank to evaluate the movement and bioaccumulation of Cr (VI) through water, sediment, a macrophyte Hydrilla, small fish guppy, and few key organs of magur, Clarias batrachus. The Cr (VI) intoxication was imposed of as a single dose of 30 mg/l concentration for a wide range of exposure durations like 1, 7, 14 and 21 days. After 1 day of exposure the total Cr (VI) load was very high in the water and sediment samples (5.187 microg/ml and 23.332 microg/g respectively) which were decreased with increasing exposure durations over their respective controls. In samples of macrophyte, Cr (VI) concentration showed a gradual increasing trend from 6.1797 microg/g in control to 21.1903 microg/g in 1 day exposure and reached up to 24.635 microg/g after 21 days exposure. In guppy, the Cr (VI) bioaccumulation showed an increasing trend but the rate was not statistically significant. However, in magur, the Cr (VI) uptake showed a significant gradual and increasing trend with increasing exposure durations in liver, brain, intestine and muscular tissues than gill and kidney over their respective controls. The movement of the Cr (VI) was found to be from sediment to water during pre-treatment phase, after intoxication, from water to macrophyte and to other phytoplankton and zooplankton. It then accumulated in the primary consumer guppy and finally moved to the secondary consumer the magur following the food web. The results reveal that the rate of movement and bioaccumulation of Cr (VI) varied from organism to organism and in C. batrachus, from tissue to tissue."
1509688,Narin et al. 2008,"A novel solid phase extraction procedure on Amberlite XAD-1180 for speciation of Cr(III), Cr(VI) and total chromium in environmental and pharmaceutical samples","Due to the toxicity of chromium, species depend on their chemical properties and bioavailabilities, speciation of chromium is very important in environmental samples. A speciation procedure for chromium(III), chromium(VI) and total chromium in environmental samples is presented in this work, prior to flame atomic absorption spectrometric determination of chromium. The procedure is based on the adsorption of Cr(III)-diphenylcarbazone complex on Amberlite XAD-1180 resin. After oxidation of Cr(III), the developed solid phase extraction system was applied to determinate the total chromium. Cr(III) was calculated as the difference between the total Cr content and the Cr(VI) content. The analytical conditions for the quantitative recoveries of Cr(VI) on Amberlite XAD-1180 resin were investigated. The effects of some alkaline, earth alkaline, metal ions and also some anions were also examined. Preconcentration factor was found to be 75. The detection limits (LOD) based on three times sigma of the blank (N: 21) for Cr(VI) and total chromium were 7.7 and 8.6 microg/L, respectively. Satisfactory results for the analysis of total chromium in the stream sediment (GBW7310) certified reference material for the validation of the presented method was obtained. The procedure was applied to food, water and pharmaceutical samples successfully.","A novel solid phase extraction procedure on Amberlite XAD-1180 for speciation of Cr(III), Cr(VI) and total chromium in environmental and pharmaceutical samples Abs: Due to the toxicity of chromium, species depend on their chemical properties and bioavailabilities, speciation of chromium is very important in environmental samples. A speciation procedure for chromium(III), chromium(VI) and total chromium in environmental samples is presented in this work, prior to flame atomic absorption spectrometric determination of chromium. The procedure is based on the adsorption of Cr(III)-diphenylcarbazone complex on Amberlite XAD-1180 resin. After oxidation of Cr(III), the developed solid phase extraction system was applied to determinate the total chromium. Cr(III) was calculated as the difference between the total Cr content and the Cr(VI) content. The analytical conditions for the quantitative recoveries of Cr(VI) on Amberlite XAD-1180 resin were investigated. The effects of some alkaline, earth alkaline, metal ions and also some anions were also examined. Preconcentration factor was found to be 75. The detection limits (LOD) based on three times sigma of the blank (N: 21) for Cr(VI) and total chromium were 7.7 and 8.6 microg/L, respectively. Satisfactory results for the analysis of total chromium in the stream sediment (GBW7310) certified reference material for the validation of the presented method was obtained. The procedure was applied to food, water and pharmaceutical samples successfully."
1509687,Lan et al. 2007,Influence of soil minerals on chromium(VI) reduction by sulfide under anoxic conditions,"The effects of soil minerals on chromate (CrVIO42-, noted as Cr(VI)) reduction by sulfide were investigated in the pH range of 7.67 to 9.07 under the anoxic condition. The examined minerals included montmorillonite (Swy-2), illite (IMt-2), kaolinite (KGa-2), aluminum oxide (gamma-Al2O3), titanium oxide (TiO2, P-25, primarily anatase), and silica (SiO2). Based on their effects on Cr(VI) reduction, these minerals were categorized into three groups: (i) minerals catalyzing Cr(VI) reduction - illite; (ii) minerals with no effect - Al2O3; and (iii) minerals inhibiting Cr(VI) reduction- kaolinite, montmorillonite, SiO2 and TiO2 . The catalysis of illite was attributed primarily to the low concentration of iron solubilized from the mineral, which could accelerate Cr(VI) reduction by shuttling electrons from sulfide to Cr(VI). Additionally, elemental sulfur produced as the primary product of sulfide oxidation could further catalyze Cr(VI) reduction in the heterogeneous system. Previous studies have shown that adsorption of sulfide onto elemental sulfur nanoparticles could greatly increase sulfide reactivity towards Cr(VI) reduction. Consequently, the observed rate constant, kobs, increased with increasing amounts of both iron solubilized from illite and elemental sulfur produced during the reaction. The catalysis of iron, however, was found to be blocked by phenanthroline, a strong complexing agent for ferrous iron. In this case, the overall reaction rate at the initial stage of reaction was pseudo first order with respect to Cr(VI), i.e., the reaction kinetics was similar to that in the homogeneous system, because elemental sulfur exerted no effect at the initial stage prior to accumulation of elemental sulfur nanoparticles. In the suspension of kaolinite, which belonged to group (iii), an inhibitive effect to Cr(VI) reduction was observed and subsequently examined in more details. The inhibition was due to the sorption of elemental sulfur onto kaolinite, which reduced or completely eliminated the catalytic effect of elemental sulfur, depending on kaolinite concentration. This was consistent with the observation that the catalysis of externally added elemental sulfur (50 muM) on Cr(VI) reduction would disappear with a kaolinite concentration of more than 5.0 g/L. In kaolinite suspension, the overall reaction rate law was:-d[Cr(VI)]/dt = kobs[H+]2[Cr(VI)][HS-]0.70.","Influence of soil minerals on chromium(VI) reduction by sulfide under anoxic conditions Abs: The effects of soil minerals on chromate (CrVIO42-, noted as Cr(VI)) reduction by sulfide were investigated in the pH range of 7.67 to 9.07 under the anoxic condition. The examined minerals included montmorillonite (Swy-2), illite (IMt-2), kaolinite (KGa-2), aluminum oxide (gamma-Al2O3), titanium oxide (TiO2, P-25, primarily anatase), and silica (SiO2). Based on their effects on Cr(VI) reduction, these minerals were categorized into three groups: (i) minerals catalyzing Cr(VI) reduction - illite; (ii) minerals with no effect - Al2O3; and (iii) minerals inhibiting Cr(VI) reduction- kaolinite, montmorillonite, SiO2 and TiO2 . The catalysis of illite was attributed primarily to the low concentration of iron solubilized from the mineral, which could accelerate Cr(VI) reduction by shuttling electrons from sulfide to Cr(VI). Additionally, elemental sulfur produced as the primary product of sulfide oxidation could further catalyze Cr(VI) reduction in the heterogeneous system. Previous studies have shown that adsorption of sulfide onto elemental sulfur nanoparticles could greatly increase sulfide reactivity towards Cr(VI) reduction. Consequently, the observed rate constant, kobs, increased with increasing amounts of both iron solubilized from illite and elemental sulfur produced during the reaction. The catalysis of iron, however, was found to be blocked by phenanthroline, a strong complexing agent for ferrous iron. In this case, the overall reaction rate at the initial stage of reaction was pseudo first order with respect to Cr(VI), i.e., the reaction kinetics was similar to that in the homogeneous system, because elemental sulfur exerted no effect at the initial stage prior to accumulation of elemental sulfur nanoparticles. In the suspension of kaolinite, which belonged to group (iii), an inhibitive effect to Cr(VI) reduction was observed and subsequently examined in more details. The inhibition was due to the sorption of elemental sulfur onto kaolinite, which reduced or completely eliminated the catalytic effect of elemental sulfur, depending on kaolinite concentration. This was consistent with the observation that the catalysis of externally added elemental sulfur (50 muM) on Cr(VI) reduction would disappear with a kaolinite concentration of more than 5.0 g/L. In kaolinite suspension, the overall reaction rate law was:-d[Cr(VI)]/dt = kobs[H+]2[Cr(VI)][HS-]0.70."
1509686,Oze et al. 2007,Genesis of hexavalent chromium from natural sources in soil and groundwater,"Naturally occurring Cr(VI) has recently been reported in ground and surface waters. Rock strata rich in Cr(III)-bearing minerals, in particular chromite, are universally found in these areas that occur near convergent plate margins. Here we report experiments demonstrating accelerated dissolution of chromite and subsequent oxidation of Cr(III) to aqueous Cr(VI) in the presence of birnessite, a common manganese mineral, explaining the generation of Cr(VI) by a Cr(III)-bearing mineral considered geochemically inert. Our results demonstrate that Cr(III) within ultramafic- and serpentinite-derived soils/sediments can be oxidized and dissolved through natural processes, leading to hazardous levels of aqueous Cr(VI) in surface and groundwater.","Genesis of hexavalent chromium from natural sources in soil and groundwater Abs: Naturally occurring Cr(VI) has recently been reported in ground and surface waters. Rock strata rich in Cr(III)-bearing minerals, in particular chromite, are universally found in these areas that occur near convergent plate margins. Here we report experiments demonstrating accelerated dissolution of chromite and subsequent oxidation of Cr(III) to aqueous Cr(VI) in the presence of birnessite, a common manganese mineral, explaining the generation of Cr(VI) by a Cr(III)-bearing mineral considered geochemically inert. Our results demonstrate that Cr(III) within ultramafic- and serpentinite-derived soils/sediments can be oxidized and dissolved through natural processes, leading to hazardous levels of aqueous Cr(VI) in surface and groundwater."
1509685,Jung et al. 2007,Spectroscopic investigation of magnetite surface for the reduction of hexavalent chromium,"The reduction of Cr(VI) to Cr(III) by magnetite in the presence of added Fe(II) was characterized through batch kinetic experiments and the effect of Fe(II) addition and pH were investigated in this study. The addition of Fe(II) into magnetite suspension improved the reductive capacity of magnetite. Eighty percent of Cr(VI) was reduced by magnetite (6.5 g l(-1)) with Fe(II) (80 mg l(-1)) within 1 h, while 60% of Cr(VI) was removed by magnetite only. However, the extent of improved reductive capacity of magnetite with Fe(II) was less than that predicted by the summation of each reduction capacity of magnetite and Fe(II). The reduction of Cr(VI) in the magnetite suspension with Fe(II) increased with the increase of molar ratio of Fe(II) to Cr(VI) (0.6, 1, 1.5, 2.3) in the range of 0-2.3 and with the decrease of pH in the range of pH 8.0-5.5. The speciation of chromium, iron, and oxygen on the surface of magnetite was investigated by X-ray photoelectron spectroscopy. Cr 2p3/2, Fe 2p3/2, and O 1s peaks were mainly observed at 576.7 and 577.8 eV, at 711.2 eV, and at 530.2 and 531.4 eV, respectively. The results indicates that Cr(III) and Fe(III) were the dominant species on the surface of magnetite after reaction and that the dominant species covered the magnetite surface and formed metal (oxy)hydroxide.","Spectroscopic investigation of magnetite surface for the reduction of hexavalent chromium Abs: The reduction of Cr(VI) to Cr(III) by magnetite in the presence of added Fe(II) was characterized through batch kinetic experiments and the effect of Fe(II) addition and pH were investigated in this study. The addition of Fe(II) into magnetite suspension improved the reductive capacity of magnetite. Eighty percent of Cr(VI) was reduced by magnetite (6.5 g l(-1)) with Fe(II) (80 mg l(-1)) within 1 h, while 60% of Cr(VI) was removed by magnetite only. However, the extent of improved reductive capacity of magnetite with Fe(II) was less than that predicted by the summation of each reduction capacity of magnetite and Fe(II). The reduction of Cr(VI) in the magnetite suspension with Fe(II) increased with the increase of molar ratio of Fe(II) to Cr(VI) (0.6, 1, 1.5, 2.3) in the range of 0-2.3 and with the decrease of pH in the range of pH 8.0-5.5. The speciation of chromium, iron, and oxygen on the surface of magnetite was investigated by X-ray photoelectron spectroscopy. Cr 2p3/2, Fe 2p3/2, and O 1s peaks were mainly observed at 576.7 and 577.8 eV, at 711.2 eV, and at 530.2 and 531.4 eV, respectively. The results indicates that Cr(III) and Fe(III) were the dominant species on the surface of magnetite after reaction and that the dominant species covered the magnetite surface and formed metal (oxy)hydroxide."
1509684,Pramanik et al. 2007,"A new chelating resin containing azophenolcarboxylate functionality: synthesis, characterization and application to chromium speciation in wastewater","The synthesis of a new stable chelating resin from the polystyrene divinylbenzene copolymer is reported. The polystyrene is first functionalized with a phenolic group and then allowed to couple with diazotized anthranilic acid through the --N==N-- bond. The resulting polymer containing azophenolcarboxylate with an ONO chelating environment has been characterized by elemental analysis, hydrogen ion capacity, and water regain value. Its stability towards thermal and different chemical environments has been evaluated. The sorption capacity of the chelating resin for Cr(III) and Cr(VI) as a function of pH has been studied. The interesting point is that chromium(III) is selectively retained at ca. pH 5.0 and chromium(VI) at ca. pH 2.0. When packed in a column, the new material is able to separate Cr(III) from Cr(VI). Five replicate determinations of 10 microg Cr(III) and 10 microg Cr(VI) present in 100 mL solution gave recoveries of 96.9+/-2.9% (for Cr(III)) and 96.2+/-2.1% (for Cr(VI)) at the 95% confidence level. Calibration graph was linear over the concentration range of 0-250 microg L(-1) of chromium species with correlation coefficient (R) of 0.99994. The detection limits based on 3sigma criterion were determined to be 0.6 microg L(-1) for Cr(III) and 0.9 microg L(-1) for Cr(VI). The developed method was successfully used for the speciation of chromium in wastewater.","A new chelating resin containing azophenolcarboxylate functionality: synthesis, characterization and application to chromium speciation in wastewater Abs: The synthesis of a new stable chelating resin from the polystyrene divinylbenzene copolymer is reported. The polystyrene is first functionalized with a phenolic group and then allowed to couple with diazotized anthranilic acid through the --N==N-- bond. The resulting polymer containing azophenolcarboxylate with an ONO chelating environment has been characterized by elemental analysis, hydrogen ion capacity, and water regain value. Its stability towards thermal and different chemical environments has been evaluated. The sorption capacity of the chelating resin for Cr(III) and Cr(VI) as a function of pH has been studied. The interesting point is that chromium(III) is selectively retained at ca. pH 5.0 and chromium(VI) at ca. pH 2.0. When packed in a column, the new material is able to separate Cr(III) from Cr(VI). Five replicate determinations of 10 microg Cr(III) and 10 microg Cr(VI) present in 100 mL solution gave recoveries of 96.9+/-2.9% (for Cr(III)) and 96.2+/-2.1% (for Cr(VI)) at the 95% confidence level. Calibration graph was linear over the concentration range of 0-250 microg L(-1) of chromium species with correlation coefficient (R) of 0.99994. The detection limits based on 3sigma criterion were determined to be 0.6 microg L(-1) for Cr(III) and 0.9 microg L(-1) for Cr(VI). The developed method was successfully used for the speciation of chromium in wastewater."
1509683,Iyer 2007,Eco-friendly rubberized cotton fabric roller for ginning machines,"This article discusses the pollution caused by chrome composite leather-clad (CCLC) rollers commonly used in cotton roller ginning mills and suggests an alternative roller material. CCLC rollers contain about 18,000 to 36,000 mg/kg (ppm) total chromium in trivalent and hexavalent forms, which are toxic to human health and carcinogenic. When seed-cotton is processed in double roller (DR) ginning machines, the lint is contaminated with chromium, and chromium particles are carried into the spun yarns and cotton by-products. Specifically, due to persistent rubbing of the leather-clad roller over the stationary knife during the ginning process, the lint is contaminated with about 140 to 1990 ppm of chromium, and the spun yarns and cotton by-products contain about 100 to 200 ppm, far in excess of the standard limit of 0.1 ppm. Gin and mill workers are directly exposed to this carcinogenic substance. To offset this problem, pollution-free rubberized cotton fabric (RCF) rollers have been fabricated and tested in roller gins. The RCF roller covering is made of multiple layers of fabric bonded together using a white rubber compound, which has a surface finish conducive to high ginning efficiency. This eliminates chromium contamination and pollution during the ginning process. On the basis of the design and development of various test rollers and subsequent evaluation studies, the performance of pollution-free RCF rollers has been demonstrated with reference to their commercial benefit and eco-friendliness in cotton ginning mills.","Eco-friendly rubberized cotton fabric roller for ginning machines Abs: This article discusses the pollution caused by chrome composite leather-clad (CCLC) rollers commonly used in cotton roller ginning mills and suggests an alternative roller material. CCLC rollers contain about 18,000 to 36,000 mg/kg (ppm) total chromium in trivalent and hexavalent forms, which are toxic to human health and carcinogenic. When seed-cotton is processed in double roller (DR) ginning machines, the lint is contaminated with chromium, and chromium particles are carried into the spun yarns and cotton by-products. Specifically, due to persistent rubbing of the leather-clad roller over the stationary knife during the ginning process, the lint is contaminated with about 140 to 1990 ppm of chromium, and the spun yarns and cotton by-products contain about 100 to 200 ppm, far in excess of the standard limit of 0.1 ppm. Gin and mill workers are directly exposed to this carcinogenic substance. To offset this problem, pollution-free rubberized cotton fabric (RCF) rollers have been fabricated and tested in roller gins. The RCF roller covering is made of multiple layers of fabric bonded together using a white rubber compound, which has a surface finish conducive to high ginning efficiency. This eliminates chromium contamination and pollution during the ginning process. On the basis of the design and development of various test rollers and subsequent evaluation studies, the performance of pollution-free RCF rollers has been demonstrated with reference to their commercial benefit and eco-friendliness in cotton ginning mills."
1509681,Horsfall et al. 2006,Sorption of chromium(VI) from aqueous solution by cassava (Manihot sculenta Cranz.) waste biomass,"The sorption of highly toxic Cr(VI) ions by cassava waste biomass was quantitatively investigated. The sorption was found to be influenced by several physico-chemical factors such as agitation speed, temperature, contact time, pH, and sorbent/sorbate ratio. The adsorption data at equilibrium were fitted to Freundlich and Langmuir isotherms. The monolayer sorption capacity was found to be 61.79 mg of Cr(VI) per gram of biomass. The kinetics of Cr(VI) adsorption to pure cassava-tuber-bark wastes were determined based on a pseudo-second-order-rate model using the batch-sorption technique at a temperature of 30 degrees. The kinetics data suggest that the adsorption process is exothermic, and that the rate-limiting step is physisorption. Negative DeltaG(ads) values indicate that the adsorption is spontaneous and exothermic in nature. Also, under optimal conditions (in agitated 1M H(2)SO(4) at 30 degrees), the cassava waste biomass appears to be recyclable.","Sorption of chromium(VI) from aqueous solution by cassava (Manihot sculenta Cranz.) waste biomass Abs: The sorption of highly toxic Cr(VI) ions by cassava waste biomass was quantitatively investigated. The sorption was found to be influenced by several physico-chemical factors such as agitation speed, temperature, contact time, pH, and sorbent/sorbate ratio. The adsorption data at equilibrium were fitted to Freundlich and Langmuir isotherms. The monolayer sorption capacity was found to be 61.79 mg of Cr(VI) per gram of biomass. The kinetics of Cr(VI) adsorption to pure cassava-tuber-bark wastes were determined based on a pseudo-second-order-rate model using the batch-sorption technique at a temperature of 30 degrees. The kinetics data suggest that the adsorption process is exothermic, and that the rate-limiting step is physisorption. Negative DeltaG(ads) values indicate that the adsorption is spontaneous and exothermic in nature. Also, under optimal conditions (in agitated 1M H(2)SO(4) at 30 degrees), the cassava waste biomass appears to be recyclable."
1509680,Natale et al. 2006,Acute and chronic effects of Cr(VI) on Hypsiboas pulchellus embryos and tadpoles,"In the last few years there has been great concern about declines in the abundance of several species of amphibians around the world. Among amphibians, anurans have a biphasic life cycle, with aquatic tadpoles and generally terrestrial adults, and they have an extremely permeable skin, making them excellent indicators of the health of the environment. A number of different causes have been suggested for the global decline of anurans, the pollution of their habitat by chemical stressors being considered one of the major factors. Among chemical stressors, heavy metals are known for their high toxicity at very low concentrations. This study assessed short- (96 h, 'acute') and long-term (1272 h, 'chronic') exposure to Cr(VI) at lethal (3 to 90 mg 1(-1)) and sublethal concentrations (0.001 to 12 mg 1(-1)) on Hypsiboaspulchellus (previously called Hyla pulchella; see Faivovich et al. 2005) tadpoles (Fam. Hylidae) from central eastern Argentina. Fertilized eggs collected from a clean pond near La Plata (Buenos Aires Province) were used for acute and chronic toxicity testing. Assays were done under controlled laboratory conditions. Results of chronic exposure were used to assess the effect of factors such as toxicant concentration and age of organisms at the beginning of exposure on the response variables (growth, development and survival until metamorphosis). Results indicated a higher sensitivity to Cr(VI) of individuals first exposed as tadpoles than those first exposed as embryos during acute and chronic exposure. Exposure to the highest sublethal concentrations (6 to 12 mg 1(-1)) of the toxicant showed early inhibitory effects on growth of all treated organisms compensated at longer exposure periods with an increase in the growth rate compared to the control groups.","Acute and chronic effects of Cr(VI) on Hypsiboas pulchellus embryos and tadpoles Abs: In the last few years there has been great concern about declines in the abundance of several species of amphibians around the world. Among amphibians, anurans have a biphasic life cycle, with aquatic tadpoles and generally terrestrial adults, and they have an extremely permeable skin, making them excellent indicators of the health of the environment. A number of different causes have been suggested for the global decline of anurans, the pollution of their habitat by chemical stressors being considered one of the major factors. Among chemical stressors, heavy metals are known for their high toxicity at very low concentrations. This study assessed short- (96 h, 'acute') and long-term (1272 h, 'chronic') exposure to Cr(VI) at lethal (3 to 90 mg 1(-1)) and sublethal concentrations (0.001 to 12 mg 1(-1)) on Hypsiboaspulchellus (previously called Hyla pulchella; see Faivovich et al. 2005) tadpoles (Fam. Hylidae) from central eastern Argentina. Fertilized eggs collected from a clean pond near La Plata (Buenos Aires Province) were used for acute and chronic toxicity testing. Assays were done under controlled laboratory conditions. Results of chronic exposure were used to assess the effect of factors such as toxicant concentration and age of organisms at the beginning of exposure on the response variables (growth, development and survival until metamorphosis). Results indicated a higher sensitivity to Cr(VI) of individuals first exposed as tadpoles than those first exposed as embryos during acute and chronic exposure. Exposure to the highest sublethal concentrations (6 to 12 mg 1(-1)) of the toxicant showed early inhibitory effects on growth of all treated organisms compensated at longer exposure periods with an increase in the growth rate compared to the control groups."
1509679,Polti et al. 2007,Chromium(VI) resistance and removal by actinomycete strains isolated from sediments,"Forty-one isolated actinomycetes were used to study qualitative and semi-quantitative screening of chromium(VI) resistance. Chromate-removing activity was estimated using the Cr(VI) specific colorimetric reagent 1,5-diphenylcarbazide. Twenty percent of the isolates from El Cadillal (EC) and 14% of isolates from a copper filter plant (CFP) were able to grow at 13 mM of Cr(VI). All isolates from sugar cane (SCP) could grow up to Cr(VI) concentration of 17 mM. EC, CFP and SCP strains were able to remove 24%, 30% and more than 40% of Cr(VI), respectively. The highest and lowest Cr(VI) specific removal values were 75.5 mg g(-1) cell by M3 (CFP), and 1.5 mg g(-1) cell by C35 (EC) strains. Eleven Cr(VI) resistant strains were characterized and identified as species of the genera Streptomyces (10) and Amycolatopsis (1). Differences on actinomycete community composition between contaminated and non-contaminated soil were found. This study showed the potential capacity of actinomycetes as tools for Cr(VI) bioremediation.","Chromium(VI) resistance and removal by actinomycete strains isolated from sediments Abs: Forty-one isolated actinomycetes were used to study qualitative and semi-quantitative screening of chromium(VI) resistance. Chromate-removing activity was estimated using the Cr(VI) specific colorimetric reagent 1,5-diphenylcarbazide. Twenty percent of the isolates from El Cadillal (EC) and 14% of isolates from a copper filter plant (CFP) were able to grow at 13 mM of Cr(VI). All isolates from sugar cane (SCP) could grow up to Cr(VI) concentration of 17 mM. EC, CFP and SCP strains were able to remove 24%, 30% and more than 40% of Cr(VI), respectively. The highest and lowest Cr(VI) specific removal values were 75.5 mg g(-1) cell by M3 (CFP), and 1.5 mg g(-1) cell by C35 (EC) strains. Eleven Cr(VI) resistant strains were characterized and identified as species of the genera Streptomyces (10) and Amycolatopsis (1). Differences on actinomycete community composition between contaminated and non-contaminated soil were found. This study showed the potential capacity of actinomycetes as tools for Cr(VI) bioremediation."
1509677,Goswami et al. 2006,Crystalline hydrous ferric oxide: an adsorbent for chromium(VI)-contaminated industrial wastewater treatment,"Synthetic crystalline hydrous ferric oxide (CHFO) (particle size 0.14 to 0.29 mm) has been used systematically for adsorptive chromium(VI) removal from contaminated water. Batch experiments were performed as a function of pH, contact time, solute concentration, and regeneration of adsorbents. Column experiments were performed for breakthrough points in the presence and absence of other ions and treatment of industrial effluent. The optimum pH range was 2.0 to 4.0. The adsorption kinetic data could be described well by both second-order and pseudo-first-order models. The isotherm adsorption data at 30 +/- 2 degrees C obeyed the Langmuir model best. The monolayer adsorption capacity was 35.7 mg/g. Chromium(VI)-rich CHFO could be regenerated up to 89 +/- 1% with 2.0 M sodium hydroxide. Regenerated column reuse showed a decrease (10 to 12%) in breakthrough capacity. Finally, the CHFO- (dried at 300 degrees C) packed column was used for the recovery (98.5 +/- 1.0%) of chromium(VI) from contaminated industrial waste effluent of Hindustan Motor Limited (Hooghly, West Bengal, India).","Crystalline hydrous ferric oxide: an adsorbent for chromium(VI)-contaminated industrial wastewater treatment Abs: Synthetic crystalline hydrous ferric oxide (CHFO) (particle size 0.14 to 0.29 mm) has been used systematically for adsorptive chromium(VI) removal from contaminated water. Batch experiments were performed as a function of pH, contact time, solute concentration, and regeneration of adsorbents. Column experiments were performed for breakthrough points in the presence and absence of other ions and treatment of industrial effluent. The optimum pH range was 2.0 to 4.0. The adsorption kinetic data could be described well by both second-order and pseudo-first-order models. The isotherm adsorption data at 30 +/- 2 degrees C obeyed the Langmuir model best. The monolayer adsorption capacity was 35.7 mg/g. Chromium(VI)-rich CHFO could be regenerated up to 89 +/- 1% with 2.0 M sodium hydroxide. Regenerated column reuse showed a decrease (10 to 12%) in breakthrough capacity. Finally, the CHFO- (dried at 300 degrees C) packed column was used for the recovery (98.5 +/- 1.0%) of chromium(VI) from contaminated industrial waste effluent of Hindustan Motor Limited (Hooghly, West Bengal, India)."
1509676,Venkataramanan et al. 2007,Oxidation of methionines by oxochromium(V) cations: a kinetic and spectral study,"The oxidation of methionine (Met) plays an important role during biological conditions of oxidative stress as well as for protein stability. By choosing [oxo(salen)chromium(V)] ions, [(salen)Cr(V)=O](+) (where salen = bis(salicylidene)ethylenediamine) as suitable biomimics for the peptide complexes that are formed during the reduction of Cr(VI) with biological reductants, the oxidation of methionine and substituted methionines with five [oxo(salen)chromium(V)] complexes in aqueous acetonitrile has been investigated by spectrophotometric, electron paramagnetic resonance (EPR) spectroscopy and electrospray ionization mass spectrometry (ESI-MS) methods. In aqueous solution [(salen)Cr(V)=O](+) ion is short lived, ligation of H(2)O to the Cr center takes place and [O=Cr(V)(salen)-H(2)O](+) adduct is the active oxidant. The reaction is found to be first order each in the oxidant and the substrate. The presence of water in the reaction system accelerates the reaction rate and an inactive, stable mu-oxo dimer is also formed during the course of the reaction. On the basis of spectral, kinetic and product analysis study a mechanism involving direct oxygen transfer from [O=Cr(V)(salen)-H(2)O](+) to methionine has been proposed as a suitable mechanism for the reaction.","Oxidation of methionines by oxochromium(V) cations: a kinetic and spectral study Abs: The oxidation of methionine (Met) plays an important role during biological conditions of oxidative stress as well as for protein stability. By choosing [oxo(salen)chromium(V)] ions, [(salen)Cr(V)=O](+) (where salen = bis(salicylidene)ethylenediamine) as suitable biomimics for the peptide complexes that are formed during the reduction of Cr(VI) with biological reductants, the oxidation of methionine and substituted methionines with five [oxo(salen)chromium(V)] complexes in aqueous acetonitrile has been investigated by spectrophotometric, electron paramagnetic resonance (EPR) spectroscopy and electrospray ionization mass spectrometry (ESI-MS) methods. In aqueous solution [(salen)Cr(V)=O](+) ion is short lived, ligation of H(2)O to the Cr center takes place and [O=Cr(V)(salen)-H(2)O](+) adduct is the active oxidant. The reaction is found to be first order each in the oxidant and the substrate. The presence of water in the reaction system accelerates the reaction rate and an inactive, stable mu-oxo dimer is also formed during the course of the reaction. On the basis of spectral, kinetic and product analysis study a mechanism involving direct oxygen transfer from [O=Cr(V)(salen)-H(2)O](+) to methionine has been proposed as a suitable mechanism for the reaction."
1509675,Cabrera et al. 2007,Bacterial removal of chromium (VI) and (III) in a continuous system,"The capacity of Acidithiobacillus ferrooxidans and Acidithiobacillus thiooxidans to reduce different concentrations of hexavalent chromium in shake flask cultures has been investigated. A. ferrooxidans reduces 100% of chromium (VI) at concentrations of 1, 2.5 and 5 ppm, but in the presence of 10 ppm only 42.9% of chromium (VI) was reduced after 11 days of incubation. A. thiooxidans showed a lower capacity to reduce this ion and total reduction of chromium (VI) was only obtained for concentrations of 1 and 2.5 ppm, whereas 64.7% and 30.5% was reached for 5 and 10 ppm, respectively, after 11 days. A continuous flow mode system was subsequently investigated, in which A. thiooxidans was immobilized on elemental sulphur and the acidic medium obtained was employed to solubilize chromium (III) and to reduce chromium (VI) present in a real electroplating waste [30% of chromium (III) and 0.1% of chromium (VI)]. The system enabled the reduction of 92.7% of hexavalent chromium and represents a promising way to treat this type of waste in the industry.","Bacterial removal of chromium (VI) and (III) in a continuous system Abs: The capacity of Acidithiobacillus ferrooxidans and Acidithiobacillus thiooxidans to reduce different concentrations of hexavalent chromium in shake flask cultures has been investigated. A. ferrooxidans reduces 100% of chromium (VI) at concentrations of 1, 2.5 and 5 ppm, but in the presence of 10 ppm only 42.9% of chromium (VI) was reduced after 11 days of incubation. A. thiooxidans showed a lower capacity to reduce this ion and total reduction of chromium (VI) was only obtained for concentrations of 1 and 2.5 ppm, whereas 64.7% and 30.5% was reached for 5 and 10 ppm, respectively, after 11 days. A continuous flow mode system was subsequently investigated, in which A. thiooxidans was immobilized on elemental sulphur and the acidic medium obtained was employed to solubilize chromium (III) and to reduce chromium (VI) present in a real electroplating waste [30% of chromium (III) and 0.1% of chromium (VI)]. The system enabled the reduction of 92.7% of hexavalent chromium and represents a promising way to treat this type of waste in the industry."
1509674,Sharma and  Weng 2007,Removal of chromium(VI) from water and wastewater by using riverbed sand: kinetic and equilibrium studies,"Cr(VI) is a priority pollutant and has been documented to be harmful to fauna, flora and human beings and chromium containing water and wastewater are hazardous. Removal of Cr(VI) by adsorption on a non-toxic natural substance, riverbed sand has been investigated. A maximum removal of 74.3% was noted at 0.50 x 10(-4)M concentration of Cr(VI) in solution. Kinetic and equilibrium studies of Cr(VI) removal have been carried out. Chemical analysis of the adsorbent revealed SiO2 to be its major component. Kinetic data of adsorption was fitted by Lagergreen's model and k(ad), the rate constant of adsorption, was found be maximum 2.69 x 10(-2)min(-1) at 25 degrees C with minimum at 35 degrees C. Values of coefficients of intra-particle diffusion and mass transfer have been determined at different values of temperature. Langmuir's model has been used for equilibrium studies and the constants have been calculated. The studies conducted show the process of Cr(VI) removal to be exothermic in nature.","Removal of chromium(VI) from water and wastewater by using riverbed sand: kinetic and equilibrium studies Abs: Cr(VI) is a priority pollutant and has been documented to be harmful to fauna, flora and human beings and chromium containing water and wastewater are hazardous. Removal of Cr(VI) by adsorption on a non-toxic natural substance, riverbed sand has been investigated. A maximum removal of 74.3% was noted at 0.50 x 10(-4)M concentration of Cr(VI) in solution. Kinetic and equilibrium studies of Cr(VI) removal have been carried out. Chemical analysis of the adsorbent revealed SiO2 to be its major component. Kinetic data of adsorption was fitted by Lagergreen's model and k(ad), the rate constant of adsorption, was found be maximum 2.69 x 10(-2)min(-1) at 25 degrees C with minimum at 35 degrees C. Values of coefficients of intra-particle diffusion and mass transfer have been determined at different values of temperature. Langmuir's model has been used for equilibrium studies and the constants have been calculated. The studies conducted show the process of Cr(VI) removal to be exothermic in nature."
1509673,Bhat et al. 2005,Removal of trace chromium (VI) from contaminated water: bio-sorption by Ipomea aquatica,"Ipomea aquatica is a wetland plant, which floats in water bodies and is being used as a vegetable. This plant has ability to remove Cr(VI) from the contaminated water by transforming Cr (VI) to Cr (III). This adsorption of Cr(VI) basically takes place in roots of this plant. The contact time required to bring down Cr(VI) concentration below the permissible level (0.05 mg/1) is 30 to 40 days for this plant, and that varies with varying initial concentration. The lower level of contamination requires greater contact time than the higher one to bring down Cr(VI) below the permissible level. Recovery (94 +/- 1%) of chromium from the treated plant has been reported in this paper, and at the same time disposal problem also dose not arise. The study revealed that the plant Ipomea aquatica adsorbs Cr(VI) from the contaminated water very slowly compared to the other reported plants.","Removal of trace chromium (VI) from contaminated water: bio-sorption by Ipomea aquatica Abs: Ipomea aquatica is a wetland plant, which floats in water bodies and is being used as a vegetable. This plant has ability to remove Cr(VI) from the contaminated water by transforming Cr (VI) to Cr (III). This adsorption of Cr(VI) basically takes place in roots of this plant. The contact time required to bring down Cr(VI) concentration below the permissible level (0.05 mg/1) is 30 to 40 days for this plant, and that varies with varying initial concentration. The lower level of contamination requires greater contact time than the higher one to bring down Cr(VI) below the permissible level. Recovery (94 +/- 1%) of chromium from the treated plant has been reported in this paper, and at the same time disposal problem also dose not arise. The study revealed that the plant Ipomea aquatica adsorbs Cr(VI) from the contaminated water very slowly compared to the other reported plants."
1509672,Stridsklev et al. 2007,Monitoring of chromium and nickel in biological fluids of grinders grinding stainless steel,"<strong>OBJECTIVE: </strong>Stainless steel (SS) welders usually spend some of their working time grinding, to finish and smoothen the welding groove. The aim of this study was to investigate possible relations between the concentrations of nickel (Ni) and chromium (Cr) in the work atmosphere generated by grinders grinding SS, and to compare the air levels to the levels of Cr and Ni in their biological fluids. Hereby, it might be possible to identify the contribution of grinding to the levels of Cr and Ni in biological fluids in SS welders. Also the airborne levels of Cr and Ni in SS grinders were compared to corresponding levels in SS welders.<br /><br /><strong>METHOD/DESIGN: </strong>The subjects examined in this study were selected among SS grinders not performing welding. Nine grinders were monitored for 1 workweek, measuring Cr and Ni in air, blood and urine. They were questioned about their exposure to Cr and Ni during their working careers.<br /><br /><strong>RESULTS: </strong>Air levels of total Cr up to 95 microg/m(3) and Ni levels up to 25 microg/m(3) were measured. Chromium(VI) (Cr(VI)) was detectable only in five air samples; the levels in the remaining samples were below the detection limit. The levels of Cr in blood and urine were also low. The levels of Ni in urine were close to those for MMA and MIG/MAG SS welders. In spite of high levels of total Cr and Ni observed in air, the levels found in biological fluids were low. The Cr levels in more than 50% of the whole blood and red cell samples and about 1/3 of the Cr-plasma levels were below the detection limits. The mean blood levels for Cr were 0.43, 0.60 and 0.35 microg/l, in whole blood, plasma and red cells, respectively. The mean levels for Cr in the urine was 1.6, 1.4 and 1.4 microg/g creatinine for the first void, just before and just after work. For Ni the mean blood levels were 0.87 microg/l in whole blood and 0.68 microg/l in plasma. The mean levels and ranges of Ni from the first void, just before and after work in urine were 3.79 microg/g creatinine, 3.39 and 4.56, respectively. The Cr concentrations found in whole blood, plasma and red cells were approximately the same as those found in the unexposed controls and among TIG SS welders, while the urinary levels were somewhat higher, but still lower than in the welders applying other welding techniques. The mean levels of Ni in the urine of grinders were higher than those of welders, except for SS welders welding the MIG/MAG-method.<br /><br /><strong>CONCLUSION: </strong>SS Grinding seems not to contribute significantly to the uptake of Cr, which may be explained by the fact that most of Cr in the air is present in the metallic (0-valent) or trivalent form, and hardly any as Cr(VI), and therefore hardly being taken up in the airways. The grinders' uptake of Ni seems to take place to the same extent as in SS welders.","Monitoring of chromium and nickel in biological fluids of grinders grinding stainless steel Abs: <strong>OBJECTIVE: </strong>Stainless steel (SS) welders usually spend some of their working time grinding, to finish and smoothen the welding groove. The aim of this study was to investigate possible relations between the concentrations of nickel (Ni) and chromium (Cr) in the work atmosphere generated by grinders grinding SS, and to compare the air levels to the levels of Cr and Ni in their biological fluids. Hereby, it might be possible to identify the contribution of grinding to the levels of Cr and Ni in biological fluids in SS welders. Also the airborne levels of Cr and Ni in SS grinders were compared to corresponding levels in SS welders.<br /><br /><strong>METHOD/DESIGN: </strong>The subjects examined in this study were selected among SS grinders not performing welding. Nine grinders were monitored for 1 workweek, measuring Cr and Ni in air, blood and urine. They were questioned about their exposure to Cr and Ni during their working careers.<br /><br /><strong>RESULTS: </strong>Air levels of total Cr up to 95 microg/m(3) and Ni levels up to 25 microg/m(3) were measured. Chromium(VI) (Cr(VI)) was detectable only in five air samples; the levels in the remaining samples were below the detection limit. The levels of Cr in blood and urine were also low. The levels of Ni in urine were close to those for MMA and MIG/MAG SS welders. In spite of high levels of total Cr and Ni observed in air, the levels found in biological fluids were low. The Cr levels in more than 50% of the whole blood and red cell samples and about 1/3 of the Cr-plasma levels were below the detection limits. The mean blood levels for Cr were 0.43, 0.60 and 0.35 microg/l, in whole blood, plasma and red cells, respectively. The mean levels for Cr in the urine was 1.6, 1.4 and 1.4 microg/g creatinine for the first void, just before and just after work. For Ni the mean blood levels were 0.87 microg/l in whole blood and 0.68 microg/l in plasma. The mean levels and ranges of Ni from the first void, just before and after work in urine were 3.79 microg/g creatinine, 3.39 and 4.56, respectively. The Cr concentrations found in whole blood, plasma and red cells were approximately the same as those found in the unexposed controls and among TIG SS welders, while the urinary levels were somewhat higher, but still lower than in the welders applying other welding techniques. The mean levels of Ni in the urine of grinders were higher than those of welders, except for SS welders welding the MIG/MAG-method.<br /><br /><strong>CONCLUSION: </strong>SS Grinding seems not to contribute significantly to the uptake of Cr, which may be explained by the fact that most of Cr in the air is present in the metallic (0-valent) or trivalent form, and hardly any as Cr(VI), and therefore hardly being taken up in the airways. The grinders' uptake of Ni seems to take place to the same extent as in SS welders."
1509671,Khateeb et al. 2006,PLA2G6 mutation underlies infantile neuroaxonal dystrophy,"Infantile neuroaxonal dystrophy (INAD) is an autosomal recessive progressive neurodegenerative disease that presents within the first 2 years of life and culminates in death by age 10 years. Affected individuals from two unrelated Bedouin Israeli kindreds were studied. Brain imaging demonstrated diffuse cerebellar atrophy and abnormal iron deposition in the medial and lateral globus pallidum. Progressive white-matter disease and reduction of the N-acetyl aspartate : chromium ratio were evident on magnetic resonance spectroscopy, suggesting loss of myelination. The clinical and radiological diagnosis of INAD was verified by sural nerve biopsy. The disease gene was mapped to a 1.17-Mb locus on chromosome 22q13.1 (LOD score 4.7 at recombination fraction 0 for SNP rs139897), and an underlying mutation common to both affected families was identified in PLA2G6, the gene encoding phospholipase A2 group VI (cytosolic, calcium-independent). These findings highlight a role of phospholipase in neurodegenerative disorders.","PLA2G6 mutation underlies infantile neuroaxonal dystrophy Abs: Infantile neuroaxonal dystrophy (INAD) is an autosomal recessive progressive neurodegenerative disease that presents within the first 2 years of life and culminates in death by age 10 years. Affected individuals from two unrelated Bedouin Israeli kindreds were studied. Brain imaging demonstrated diffuse cerebellar atrophy and abnormal iron deposition in the medial and lateral globus pallidum. Progressive white-matter disease and reduction of the N-acetyl aspartate : chromium ratio were evident on magnetic resonance spectroscopy, suggesting loss of myelination. The clinical and radiological diagnosis of INAD was verified by sural nerve biopsy. The disease gene was mapped to a 1.17-Mb locus on chromosome 22q13.1 (LOD score 4.7 at recombination fraction 0 for SNP rs139897), and an underlying mutation common to both affected families was identified in PLA2G6, the gene encoding phospholipase A2 group VI (cytosolic, calcium-independent). These findings highlight a role of phospholipase in neurodegenerative disorders."
1509670,Wang and  Xue 2006,Sequential injection analysis for Cr(VI) and Cr(III) with renewable surface reflection spectrophotometry,"On the basis of the chromogenic reaction of chromium(VI) with 1,5-diphenylcarbohydrazide (DPC) on the surface of Polysorb C-18 beads and the sequential injection renewable surface technique (SI-RST), a highly sensitive reflect spectrophotometric method for the determination of chromium(III) and chromium(VI) was proposed. Considerations of system and flow cell design, and factors that influence the determination performance were discussed. With 300 microl of sample loaded and 0.6 mg of beads trapped, the linear response range was 0.02 - 0.5 mg l(-1) Cr(VI) with a detection limit (3 sigma) of 2.4 microg l(-1) Cr(VI). The method achieves a precision of 1.3% RSD (n = 11) and a throughput of 53 samples per hour. The determination of Cr(III) was based on the same reaction for the determination of Cr(VI) after being oxidized by (NH4)2S2O8. The precision of the oxidation method was evaluated using a 0.2 mg l(-1) Cr(III) standard, yielding an RSD of 2.5% (n = 11). The average recovery of Cr(III) oxidized was tested to be 99.1%. The proposed method was used in the simultaneous determination of Cr(VI) and Cr(III) in water samples, and the error was less than 3%.","Sequential injection analysis for Cr(VI) and Cr(III) with renewable surface reflection spectrophotometry Abs: On the basis of the chromogenic reaction of chromium(VI) with 1,5-diphenylcarbohydrazide (DPC) on the surface of Polysorb C-18 beads and the sequential injection renewable surface technique (SI-RST), a highly sensitive reflect spectrophotometric method for the determination of chromium(III) and chromium(VI) was proposed. Considerations of system and flow cell design, and factors that influence the determination performance were discussed. With 300 microl of sample loaded and 0.6 mg of beads trapped, the linear response range was 0.02 - 0.5 mg l(-1) Cr(VI) with a detection limit (3 sigma) of 2.4 microg l(-1) Cr(VI). The method achieves a precision of 1.3% RSD (n = 11) and a throughput of 53 samples per hour. The determination of Cr(III) was based on the same reaction for the determination of Cr(VI) after being oxidized by (NH4)2S2O8. The precision of the oxidation method was evaluated using a 0.2 mg l(-1) Cr(III) standard, yielding an RSD of 2.5% (n = 11). The average recovery of Cr(III) oxidized was tested to be 99.1%. The proposed method was used in the simultaneous determination of Cr(VI) and Cr(III) in water samples, and the error was less than 3%."
1509669,Yang et al. 2006,"Application of double-spike isotope dilution for the accurate determination of Cr(III), Cr(VI) and total Cr in yeast","A method is presented for the simultaneous determination of Cr(III) and Cr(VI) in yeast using species-specific double-spike isotope dilution (SSDSID) with anion-exchange liquid chromatography (LC) separation and sector field inductively coupled plasma mass spectrometric (SF-ICP-MS) detection. Total Cr is quantitated using ID SF-ICP-MS. Samples were digested on a hot plate at 95+/-2 degrees C for 6 h in an alkaline solution of 0.5 M NaOH and 0.28 M Na2CO3 for the determination of Cr(III) and Cr(VI), whereas microwave-assisted decomposition with HNO3 and H2O2 was used for the determination of total Cr. Concentrations of 2,014+/-16, 1,952+/-103 and 76+/-48 mg kg-1 (one standard deviation, n=4, 3, 3), respectively were obtained for total Cr, Cr(III) and Cr(VI) in the yeast sample. Significant oxidation of Cr(III) to Cr(VI) (24.2+/-7.6% Cr(III) oxidized, n=3) and reduction of Cr(VI) to Cr(III) (37.6+/-6.5% Cr(VI) reduced, n=3) occurred during alkaline extraction and subsequent chromatographic separation at pH 7. Despite this significant bidirectional redox transformation, quantitative recoveries for both Cr(III) and Cr(VI) were achieved using the SSDSID method. In addition, mass balance between total Cr and the sum of Cr(III) and Cr(VI) concentrations was achieved. Method detection limits of 0.3, 2 and 30 mg kg-1 were obtained for total Cr, Cr(VI) and Cr(III), respectively, based on a 0.2-g sub-sample.","Application of double-spike isotope dilution for the accurate determination of Cr(III), Cr(VI) and total Cr in yeast Abs: A method is presented for the simultaneous determination of Cr(III) and Cr(VI) in yeast using species-specific double-spike isotope dilution (SSDSID) with anion-exchange liquid chromatography (LC) separation and sector field inductively coupled plasma mass spectrometric (SF-ICP-MS) detection. Total Cr is quantitated using ID SF-ICP-MS. Samples were digested on a hot plate at 95+/-2 degrees C for 6 h in an alkaline solution of 0.5 M NaOH and 0.28 M Na2CO3 for the determination of Cr(III) and Cr(VI), whereas microwave-assisted decomposition with HNO3 and H2O2 was used for the determination of total Cr. Concentrations of 2,014+/-16, 1,952+/-103 and 76+/-48 mg kg-1 (one standard deviation, n=4, 3, 3), respectively were obtained for total Cr, Cr(III) and Cr(VI) in the yeast sample. Significant oxidation of Cr(III) to Cr(VI) (24.2+/-7.6% Cr(III) oxidized, n=3) and reduction of Cr(VI) to Cr(III) (37.6+/-6.5% Cr(VI) reduced, n=3) occurred during alkaline extraction and subsequent chromatographic separation at pH 7. Despite this significant bidirectional redox transformation, quantitative recoveries for both Cr(III) and Cr(VI) were achieved using the SSDSID method. In addition, mass balance between total Cr and the sum of Cr(III) and Cr(VI) concentrations was achieved. Method detection limits of 0.3, 2 and 30 mg kg-1 were obtained for total Cr, Cr(VI) and Cr(III), respectively, based on a 0.2-g sub-sample."
1509668,Nakamura and  Frei 2006,Visible light-driven water oxidation by Ir oxide clusters coupled to single Cr centers in mesoporous silica,"Visible light-induced water oxidation has been demonstrated at an Ir oxide nanocluster coupled to a single CrVI site on the pore surface of MCM-41 mesoporous silica. The photocatalytic unit was assembled by the reaction of surface Cr=O groups with Ir(acac)3 precursor followed by calcination at 300 degrees C and bond formation monitored by FT-Raman and FT-IR spectroscopy. High-resolution Z-contrast electron micrographs of the calcined material combined with energy-dispersive X-ray spot analysis confirmed the occlusion of Ir oxide nanoparticles inside the mesopores. Oxygen evolution of an aqueous suspension of the IrxOy-CrMCM-41 upon visible light irradiation of the CrVI-O ligand-to-metal charge-transfer absorption was monitored mass-spectrometrically. Comparison of the product yields for samples with low Cr content (Cr/Si &lt;/= 0.02) and high Cr content (Cr/Si = 0.05) indicates that only isolated Cr centers are capable of extracting electrons from Ir oxide clusters, while di- or polychromate species are not. Water oxidation at a multielectron-transfer catalyst coupled to a single metal center has not been demonstrated before. The ability to drive water oxidation with a single metal center as electron pump offers opportunities for coupling the oxygen-evolving photocatalytic unit to reducing sites in the nanoporous scaffold.","Visible light-driven water oxidation by Ir oxide clusters coupled to single Cr centers in mesoporous silica Abs: Visible light-induced water oxidation has been demonstrated at an Ir oxide nanocluster coupled to a single CrVI site on the pore surface of MCM-41 mesoporous silica. The photocatalytic unit was assembled by the reaction of surface Cr=O groups with Ir(acac)3 precursor followed by calcination at 300 degrees C and bond formation monitored by FT-Raman and FT-IR spectroscopy. High-resolution Z-contrast electron micrographs of the calcined material combined with energy-dispersive X-ray spot analysis confirmed the occlusion of Ir oxide nanoparticles inside the mesopores. Oxygen evolution of an aqueous suspension of the IrxOy-CrMCM-41 upon visible light irradiation of the CrVI-O ligand-to-metal charge-transfer absorption was monitored mass-spectrometrically. Comparison of the product yields for samples with low Cr content (Cr/Si &lt;/= 0.02) and high Cr content (Cr/Si = 0.05) indicates that only isolated Cr centers are capable of extracting electrons from Ir oxide clusters, while di- or polychromate species are not. Water oxidation at a multielectron-transfer catalyst coupled to a single metal center has not been demonstrated before. The ability to drive water oxidation with a single metal center as electron pump offers opportunities for coupling the oxygen-evolving photocatalytic unit to reducing sites in the nanoporous scaffold."
1509667,Egorov et al. 2006,Equilibration-based preconcentrating minicolumn sensors for trace level monitoring of radionuclides and metal ions in water without consumable reagents,"A sensor technique is described that captures analyte species on a preconcentrating minicolumn containing a selective solid-phase sorbent. In this approach, the sample is pumped through the column until the sorbent phase is fully equilibrated with the sample concentration, and the exit concentration equals the inlet concentration. On-column detection of the captured analytes using radiometric and spectroscopic methods is demonstrated. In trace level detection applications, this sensor provides a steady-state signal that is proportional to sample analyte concentration and is reversible. The method is demonstrated for the detection of Tc-99 using anion-exchange beads mixed with scintillating beads and light detection, Sr-90 using SuperLig 620 beads mixed with scintillating beads and light detection; and hexavalent chromium detection using anion-exchange beads with spectroscopic detection. Theory has been developed to describe the signal at equilibration and to describe analyte uptake as a function of volume and concentration, using parameters and concepts from frontal chromatography. It is shown that experimental sensor behavior closely matches theoretical predictions and that effective sensors can be prepared using low plate number columns. This sensor modality has many desirable characteristics for in situ sensors for trace level contaminant long-term monitoring where the use of consumable reagents for sensor regeneration would be undesirable. Initial experiments in groundwater matrixes demonstrated the detection of Tc-99 at drinking water level standards (activity of 0.033 Bq/mL) and detection of hexavalent chromium to levels below drinking water standards of 50 ppb.","Equilibration-based preconcentrating minicolumn sensors for trace level monitoring of radionuclides and metal ions in water without consumable reagents Abs: A sensor technique is described that captures analyte species on a preconcentrating minicolumn containing a selective solid-phase sorbent. In this approach, the sample is pumped through the column until the sorbent phase is fully equilibrated with the sample concentration, and the exit concentration equals the inlet concentration. On-column detection of the captured analytes using radiometric and spectroscopic methods is demonstrated. In trace level detection applications, this sensor provides a steady-state signal that is proportional to sample analyte concentration and is reversible. The method is demonstrated for the detection of Tc-99 using anion-exchange beads mixed with scintillating beads and light detection, Sr-90 using SuperLig 620 beads mixed with scintillating beads and light detection; and hexavalent chromium detection using anion-exchange beads with spectroscopic detection. Theory has been developed to describe the signal at equilibration and to describe analyte uptake as a function of volume and concentration, using parameters and concepts from frontal chromatography. It is shown that experimental sensor behavior closely matches theoretical predictions and that effective sensors can be prepared using low plate number columns. This sensor modality has many desirable characteristics for in situ sensors for trace level contaminant long-term monitoring where the use of consumable reagents for sensor regeneration would be undesirable. Initial experiments in groundwater matrixes demonstrated the detection of Tc-99 at drinking water level standards (activity of 0.033 Bq/mL) and detection of hexavalent chromium to levels below drinking water standards of 50 ppb."
1509666,Wang et al. 2006,Selective fluorescence determination of chromium (VI) in water samples with terbium composite nanoparticles,"The strong fluorescence Tb/acetyl acetone (acac)/Poly (Acrylamide) (PAM) composite nanoparticles have been prepared under ultrasonic radiation. The nanoparticles were water-soluble, stable and have extremely narrow emission bands and high internal quantum efficiencies. Based on the fluorescence quenching of Tb/acac/PAM by Cr (VI), a method for the selective determination of Cr (VI), without separation of Cr (III) in water, was developed. The reaction condition between Cr (VI) and Tb/acac/PAM were investigated in detail. Under optimal experimental conditions, the linear calibration curve was obtained over the concentration range of 5-600 ng mL(-1) with a correlation coefficient of 0.9939. The corresponding detection limit is 0.8 ng mL(-1) and the relative standard deviation is 1.5% for 0.05 microg mL(-1) (n=7). The proposed method has been applied to the selective quantification of Cr (VI) in synthetic samples and waste-water samples with the satisfactory results. The assay is characterized by short reaction time, very few interference, stable fluorescence signals, simple instrument and simplicity.","Selective fluorescence determination of chromium (VI) in water samples with terbium composite nanoparticles Abs: The strong fluorescence Tb/acetyl acetone (acac)/Poly (Acrylamide) (PAM) composite nanoparticles have been prepared under ultrasonic radiation. The nanoparticles were water-soluble, stable and have extremely narrow emission bands and high internal quantum efficiencies. Based on the fluorescence quenching of Tb/acac/PAM by Cr (VI), a method for the selective determination of Cr (VI), without separation of Cr (III) in water, was developed. The reaction condition between Cr (VI) and Tb/acac/PAM were investigated in detail. Under optimal experimental conditions, the linear calibration curve was obtained over the concentration range of 5-600 ng mL(-1) with a correlation coefficient of 0.9939. The corresponding detection limit is 0.8 ng mL(-1) and the relative standard deviation is 1.5% for 0.05 microg mL(-1) (n=7). The proposed method has been applied to the selective quantification of Cr (VI) in synthetic samples and waste-water samples with the satisfactory results. The assay is characterized by short reaction time, very few interference, stable fluorescence signals, simple instrument and simplicity."
1509665,Srivastava and  Thakur 2006,Biosorption potency of Aspergillus niger for removal of chromium (VI),"Aspergillus niger isolated from soil and effluent of leather tanning mills had higher activity to remove chromium. The potency of Aspergillus niger was evaluated in shake flask culture by absorption of chromium at pH 6 and temperature 30 degrees C. The results of the study indicated removal of more than 75% chromium by Aspergillus niger determined by diphenylcarbazide colorimetric assay and atomic absorption spectrophotometry after 7 days. Study of microbial Cr(VI) reduction and identification of reduction intermediates has been hindered by the lack of analytical techniques that can identify the oxidation state with subcellular spatial resolution. Therefore, removal of chromium was further substantiated by transmission electron microscopy (TEM), scanning electron microscopy (SEM), and energy-dispersive X-ray spectroscopy (EDX), which indicated an accumulation of chromium in the fungal mycelium.","Biosorption potency of Aspergillus niger for removal of chromium (VI) Abs: Aspergillus niger isolated from soil and effluent of leather tanning mills had higher activity to remove chromium. The potency of Aspergillus niger was evaluated in shake flask culture by absorption of chromium at pH 6 and temperature 30 degrees C. The results of the study indicated removal of more than 75% chromium by Aspergillus niger determined by diphenylcarbazide colorimetric assay and atomic absorption spectrophotometry after 7 days. Study of microbial Cr(VI) reduction and identification of reduction intermediates has been hindered by the lack of analytical techniques that can identify the oxidation state with subcellular spatial resolution. Therefore, removal of chromium was further substantiated by transmission electron microscopy (TEM), scanning electron microscopy (SEM), and energy-dispersive X-ray spectroscopy (EDX), which indicated an accumulation of chromium in the fungal mycelium."
1509664,Li et al. 2006,Study on chromium (VI) reduction kinetics by Pseudomonas aeruginosa using a combined system of acoustic wave impedance analyzer and UV-vis spectrophotometer,"A novel system combining acoustic wave impedance (AWI) analyzer with UV-vis spectrophotometer was developed for the study of chromium (VI) reduction kinetics by Pseudomonas aeruginosa. AWI gave information about the growth of Pseudomonas aeruginosa, and UV-vis spectrophotometer gave information about the concentration of chromium (VI) simultaneously. A combined system response model, for chromium (VI) reduction kinetics at lower initial chromium (VI) concentrations, was derived and proved based on the novel system. Taking into account the effect of bacterial growth on chromium (VI) reduction, the new model successfully simulated chromium (VI) bioremediation process. By fitting chromium (VI) reduction data toward the derived model, the kinetic parameters related to the process were obtained. When the concentration of peptone was 10 g L(-1), the half-velocity reduction rate constant K (C) and the maximum specific chromium (VI) reduction rate constant nu(max) were 0.7682 mg chromium (VI) L(-1) and 2.5814 x 10(-12) mg chromium (VI) cells(-1) h(-1), respectively. It was found that the combined system can provide real-time, reliable, and two-dimensional kinetic information, and can be applied to study other biological processes.","Study on chromium (VI) reduction kinetics by Pseudomonas aeruginosa using a combined system of acoustic wave impedance analyzer and UV-vis spectrophotometer Abs: A novel system combining acoustic wave impedance (AWI) analyzer with UV-vis spectrophotometer was developed for the study of chromium (VI) reduction kinetics by Pseudomonas aeruginosa. AWI gave information about the growth of Pseudomonas aeruginosa, and UV-vis spectrophotometer gave information about the concentration of chromium (VI) simultaneously. A combined system response model, for chromium (VI) reduction kinetics at lower initial chromium (VI) concentrations, was derived and proved based on the novel system. Taking into account the effect of bacterial growth on chromium (VI) reduction, the new model successfully simulated chromium (VI) bioremediation process. By fitting chromium (VI) reduction data toward the derived model, the kinetic parameters related to the process were obtained. When the concentration of peptone was 10 g L(-1), the half-velocity reduction rate constant K (C) and the maximum specific chromium (VI) reduction rate constant nu(max) were 0.7682 mg chromium (VI) L(-1) and 2.5814 x 10(-12) mg chromium (VI) cells(-1) h(-1), respectively. It was found that the combined system can provide real-time, reliable, and two-dimensional kinetic information, and can be applied to study other biological processes."
1509663,Al-Abadleh et al. 2005,Control of carboxylic acid and ester groups on chromium (VI) binding to functionalized silica/water interfaces studied by second harmonic generation,"Resonantly enhanced surface second harmonic generation (SHG) measurements carried out at pH 7 and room temperature were performed to study how surface-bound carboxylic acid and methyl ester functional groups control the interaction of chromate ions with fused silica/water interfaces. These functional groups were chosen because of their high abundance in humic and fulvic acids and related biopolymers commonly found in soils. They were anchored to the silica surface using organosilane chemistry to avoid competing complexation processes in the aqueous solution as well as competitive adsorption of the organic compounds and chromate. The SHG experiments were carried out at room temperature and pH 7 while using environmentally representative chromate concentrations ranging from 1 x10(-6) to 2 x 10(-4) M. Chromate is found to bind to the acid- and ester-functionalized silica/water interfaces in a reversible fashion. In contrast to the plain silica/water interface, chromate binding studies performed on the functionalized silica/water interfaces show S-shaped adsorption isotherms that can be modeled using the Frumkin-Fowler-Guggenheim (FFG) model. This model predicts a coverage-dependent binding constant of K(ads) x exp(gtheta). Values for g are found to be 3.2(2), 2.1(2), and 1.3(2) for the carboxylic acid-, the ester-, and the nonfunctionalized silica/water interfaces, respectively, and are consistent with stabilizing lateral adsorbate-adsorbate interactions among the Cr(VI) species adsorbed to the functionalized surfaces. The FFG model allows for the parametrization of the solid-liquid partition coefficient and chromate retardation factors in silica-rich soil particles whose surfaces contain organic adlayers rich in carboxylic acid and methyl ester groups. The straightforward model presented here predicts that chromate retardation increases by up to 200% when carboxylic acid functional groups are present at the silica/water interface. Increases up to 50% are predicted for methyl ester-containing organic adlayers, and the retardation factor remains effectively near unity for the plain silica/water interface (no siloxanes present).","Control of carboxylic acid and ester groups on chromium (VI) binding to functionalized silica/water interfaces studied by second harmonic generation Abs: Resonantly enhanced surface second harmonic generation (SHG) measurements carried out at pH 7 and room temperature were performed to study how surface-bound carboxylic acid and methyl ester functional groups control the interaction of chromate ions with fused silica/water interfaces. These functional groups were chosen because of their high abundance in humic and fulvic acids and related biopolymers commonly found in soils. They were anchored to the silica surface using organosilane chemistry to avoid competing complexation processes in the aqueous solution as well as competitive adsorption of the organic compounds and chromate. The SHG experiments were carried out at room temperature and pH 7 while using environmentally representative chromate concentrations ranging from 1 x10(-6) to 2 x 10(-4) M. Chromate is found to bind to the acid- and ester-functionalized silica/water interfaces in a reversible fashion. In contrast to the plain silica/water interface, chromate binding studies performed on the functionalized silica/water interfaces show S-shaped adsorption isotherms that can be modeled using the Frumkin-Fowler-Guggenheim (FFG) model. This model predicts a coverage-dependent binding constant of K(ads) x exp(gtheta). Values for g are found to be 3.2(2), 2.1(2), and 1.3(2) for the carboxylic acid-, the ester-, and the nonfunctionalized silica/water interfaces, respectively, and are consistent with stabilizing lateral adsorbate-adsorbate interactions among the Cr(VI) species adsorbed to the functionalized surfaces. The FFG model allows for the parametrization of the solid-liquid partition coefficient and chromate retardation factors in silica-rich soil particles whose surfaces contain organic adlayers rich in carboxylic acid and methyl ester groups. The straightforward model presented here predicts that chromate retardation increases by up to 200% when carboxylic acid functional groups are present at the silica/water interface. Increases up to 50% are predicted for methyl ester-containing organic adlayers, and the retardation factor remains effectively near unity for the plain silica/water interface (no siloxanes present)."
1509662,Yavuz et al. 2006,Factors affecting the adsorption of chromium (VI) on activated carbon,"The aim of this investigation was to determine the adsorption behavior of chromium (VI) on two different activated carbon samples produced from Tuncbilek lignite. The effects of the initial chromium (VI) concentration (250-1000 mg/L), temperature (297-323 K) and pH (2.0-9.5) on adsorption were investigated systematically. The effectiveness of the parameters on chromium adsorption was found to be in the order of pH, the initial Cr(VI) concentration and the temperature. Increasing the pH from 2.0 to 9.5 caused a decrease in adsorption. However, the adsorption was increased by increasing the initial Cr(VI) concentration and temperature. The multilinear mathematical model was also developed to predict the Cr(VI) adsorption on activated carbon samples within the experimental conditions.","Factors affecting the adsorption of chromium (VI) on activated carbon Abs: The aim of this investigation was to determine the adsorption behavior of chromium (VI) on two different activated carbon samples produced from Tuncbilek lignite. The effects of the initial chromium (VI) concentration (250-1000 mg/L), temperature (297-323 K) and pH (2.0-9.5) on adsorption were investigated systematically. The effectiveness of the parameters on chromium adsorption was found to be in the order of pH, the initial Cr(VI) concentration and the temperature. Increasing the pH from 2.0 to 9.5 caused a decrease in adsorption. However, the adsorption was increased by increasing the initial Cr(VI) concentration and temperature. The multilinear mathematical model was also developed to predict the Cr(VI) adsorption on activated carbon samples within the experimental conditions."
1509661,Grabarczyk et al. 2006,Extraction and determination of hexavalent chromium in soil samples,A procedure for the extraction of Cr(VI) from solid soil-like samples was presented in which the complexing properties of diethylenetriaminepentaacetic acid (DTPA) were exploited to extract insoluble compounds of Cr(VI). A concentration of DTPA in an ammonium sulphate/ammonium hydroxide buffer equal to 0.02 mol l(-1) was chosen. The conditions of extraction of insoluble Cr(VI) from solid samples were optimised using soil certified reference material spiked with known concentration of insoluble Cr(VI) added as PbCrO(4). The extracts were analysed by adsorptive stripping voltammetry. Validation of the proposed procedure of extraction was carried out by analysis of certified reference material (CRM) 545 and comparison of the results obtained using the proposed and other methods of extraction in the course of analysis of natural soil samples.,Extraction and determination of hexavalent chromium in soil samples Abs: A procedure for the extraction of Cr(VI) from solid soil-like samples was presented in which the complexing properties of diethylenetriaminepentaacetic acid (DTPA) were exploited to extract insoluble compounds of Cr(VI). A concentration of DTPA in an ammonium sulphate/ammonium hydroxide buffer equal to 0.02 mol l(-1) was chosen. The conditions of extraction of insoluble Cr(VI) from solid samples were optimised using soil certified reference material spiked with known concentration of insoluble Cr(VI) added as PbCrO(4). The extracts were analysed by adsorptive stripping voltammetry. Validation of the proposed procedure of extraction was carried out by analysis of certified reference material (CRM) 545 and comparison of the results obtained using the proposed and other methods of extraction in the course of analysis of natural soil samples.
1509660,Sheth and  Soni 2005,"Comparative study of removal of Cr(VI) with PAC, GAC and adsorbent prepared from tobacco roots","Tobacco roots activated carbon (TRAC) has been prepared from tobacco roots impregnated with 20% of ZnCl2 and carbonized at 6000 degrees C. Its adsorption capacity has been tested for the treatment of wastewater containing hexavalent chromium. The experiments were carried out in a batch process to study the different system variables such as concentration, adsorbent dosage and contact time. Removal of chromium in the process has been found to increase with increase in adsorbent dosage and contact time. The adsorption isotherm data fitted the Langmuir adsorption isotherm model.","Comparative study of removal of Cr(VI) with PAC, GAC and adsorbent prepared from tobacco roots Abs: Tobacco roots activated carbon (TRAC) has been prepared from tobacco roots impregnated with 20% of ZnCl2 and carbonized at 6000 degrees C. Its adsorption capacity has been tested for the treatment of wastewater containing hexavalent chromium. The experiments were carried out in a batch process to study the different system variables such as concentration, adsorbent dosage and contact time. Removal of chromium in the process has been found to increase with increase in adsorbent dosage and contact time. The adsorption isotherm data fitted the Langmuir adsorption isotherm model."
1509659,Jugade and  Joshi 2006,Highly sensitive adsorptive stripping voltammetric method for the ultra-trace determination of chromium(VI),"A rapid differential pulse adsorptive stripping voltammetric method has been developed for the ultra-trace determination of chromium using 2,2'-bipyridine. The base electrolyte used is 0.1 M NH4Cl (pH 6.0). The peak current was found to increase substantially with the addition of nitrite ions. A well-defined peak was observed at -1.3 V. Parameters, like concentration of the ligand, concentration of nitrite ion, accumulation potential, accumulation time, rest period, drop size, scan rate, pulse amplitude etc. have been optimized. Under the optimum conditions, the 3 sigma detection limit was found to be 0.02 ppb (3.8 x 10(-10) M). The method is highly selective and sensitive, and has been applied to the determination of Cr(VI) in spiked water, effluents and ore samples.","Highly sensitive adsorptive stripping voltammetric method for the ultra-trace determination of chromium(VI) Abs: A rapid differential pulse adsorptive stripping voltammetric method has been developed for the ultra-trace determination of chromium using 2,2'-bipyridine. The base electrolyte used is 0.1 M NH4Cl (pH 6.0). The peak current was found to increase substantially with the addition of nitrite ions. A well-defined peak was observed at -1.3 V. Parameters, like concentration of the ligand, concentration of nitrite ion, accumulation potential, accumulation time, rest period, drop size, scan rate, pulse amplitude etc. have been optimized. Under the optimum conditions, the 3 sigma detection limit was found to be 0.02 ppb (3.8 x 10(-10) M). The method is highly selective and sensitive, and has been applied to the determination of Cr(VI) in spiked water, effluents and ore samples."
1509658,Jun et al. 2006,Temperature-based rapid toxicity test using Ceriodaphnia dubia,"Toxicants, which may cause the inhibition to the biological process in sewage/wastewater treatment plant, need to be monitored within short time to prevent from serious damage. A new method, Temperature-based rapid toxicity test (TempTox test) using Ceriodaphnia dubia, was developed and compared with the standard 48 hr acute bioassay (Std. 48-hr test). Inorganic toxicants of cadmium, zinc, copper, cyanide, chromium (III), chromium (VI) and organic toxicants of phenol, PCP and pesticides of BPMC, Diazinon, Fenitrothion were tested for TempTox test and Std. 48-hr test. Because the TempTox test is based on just temperature control, C. dubia neonates were exposed to toxicants under high temperature (35.5 degrees C) condition without any complicated pretreatment. After given exposure time of 1, 1.25, 1.5 hours, the number of the live (no toxic effect) or the dead (toxic effect) was counted with eye without the aid of any microscope and median effective concentrations (EC50 values) were determined. From the results for all toxicants, the TempTox test was proved to be as sensitive as the Std. 48-hr test with shorter-time of just 1.25-1.5 hours. Moreover, the TempTox test was further much more sensitive than alternative bioassays such as the 1-hour l.Q. test and 30-minute Microtox. The TempTox test showed a high applicability of toxicity bioassay for real sewage/wastewater treatment plant by its easiness, rapidity and sensitivity. Finally, the prototype for short-term TempTox test was introduced.","Temperature-based rapid toxicity test using Ceriodaphnia dubia Abs: Toxicants, which may cause the inhibition to the biological process in sewage/wastewater treatment plant, need to be monitored within short time to prevent from serious damage. A new method, Temperature-based rapid toxicity test (TempTox test) using Ceriodaphnia dubia, was developed and compared with the standard 48 hr acute bioassay (Std. 48-hr test). Inorganic toxicants of cadmium, zinc, copper, cyanide, chromium (III), chromium (VI) and organic toxicants of phenol, PCP and pesticides of BPMC, Diazinon, Fenitrothion were tested for TempTox test and Std. 48-hr test. Because the TempTox test is based on just temperature control, C. dubia neonates were exposed to toxicants under high temperature (35.5 degrees C) condition without any complicated pretreatment. After given exposure time of 1, 1.25, 1.5 hours, the number of the live (no toxic effect) or the dead (toxic effect) was counted with eye without the aid of any microscope and median effective concentrations (EC50 values) were determined. From the results for all toxicants, the TempTox test was proved to be as sensitive as the Std. 48-hr test with shorter-time of just 1.25-1.5 hours. Moreover, the TempTox test was further much more sensitive than alternative bioassays such as the 1-hour l.Q. test and 30-minute Microtox. The TempTox test showed a high applicability of toxicity bioassay for real sewage/wastewater treatment plant by its easiness, rapidity and sensitivity. Finally, the prototype for short-term TempTox test was introduced."
1509657,Bardiya et al. 2004,"Interference of thiosulfate during colorimetric analysis of hexavalent chromium using 1,5-diphenylcarbazide method","Thiosulfate (S(2)O(3)(2-)) contained in the media for autotrophic Cr (VI) reduction was found to interfere with Cr (VI) measurement following the 1,5-diphenylcarbazide (DPC) method. The interference was confirmed at several abiotic and biotic conditions, and was influenced by S(2)O(3)(2-) concentration, pH, and the media components. At neutral to alkaline pH, 500 mg/L of S(2)O(3)(2-) did not cause interference, while 4 mg/L of S(2)O(3)(2-) resulted in the interference at pH 2.0. Atomic absorption spectrophotometry could be an alternative method when the interference by S(2)O(3)(2-) is expected.","Interference of thiosulfate during colorimetric analysis of hexavalent chromium using 1,5-diphenylcarbazide method Abs: Thiosulfate (S(2)O(3)(2-)) contained in the media for autotrophic Cr (VI) reduction was found to interfere with Cr (VI) measurement following the 1,5-diphenylcarbazide (DPC) method. The interference was confirmed at several abiotic and biotic conditions, and was influenced by S(2)O(3)(2-) concentration, pH, and the media components. At neutral to alkaline pH, 500 mg/L of S(2)O(3)(2-) did not cause interference, while 4 mg/L of S(2)O(3)(2-) resulted in the interference at pH 2.0. Atomic absorption spectrophotometry could be an alternative method when the interference by S(2)O(3)(2-) is expected."
1509656,Wellman et al. 2006,Synthesis of organically templated nanoporous Tin(II/IV) phosphate for radionuclide and metal sequestration,"Nanoporous tin(II/IV) phosphate materials, with spherical morphology, have been synthesized using cetyltrimethylammonium chloride [CH3(CH2)15N(CH3)3Cl] as the surfactant. The structure of the material is stable at 500 degrees C; however, partial oxidation of the material occurs with redox conversion of Sn2+ to Sn4+, resulting in a mixed Sn(II)/Sn(IV) material. Preliminary batch contact studies were conducted to assess the effectiveness of nanoporous tin phosphate, NP-SnPO, in sequestering redox-sensitive metals and radionuclides, technetium(VII), neptunium(V), thorium(IV), and a toxic metal, chromium(VI), from aqueous matrixes. Results indicate that tin(II) phosphate removed &gt;95% of all contaminants investigated from solution.","Synthesis of organically templated nanoporous Tin(II/IV) phosphate for radionuclide and metal sequestration Abs: Nanoporous tin(II/IV) phosphate materials, with spherical morphology, have been synthesized using cetyltrimethylammonium chloride [CH3(CH2)15N(CH3)3Cl] as the surfactant. The structure of the material is stable at 500 degrees C; however, partial oxidation of the material occurs with redox conversion of Sn2+ to Sn4+, resulting in a mixed Sn(II)/Sn(IV) material. Preliminary batch contact studies were conducted to assess the effectiveness of nanoporous tin phosphate, NP-SnPO, in sequestering redox-sensitive metals and radionuclides, technetium(VII), neptunium(V), thorium(IV), and a toxic metal, chromium(VI), from aqueous matrixes. Results indicate that tin(II) phosphate removed &gt;95% of all contaminants investigated from solution."
1509653,Branco et al. 2005,Impact of chromium-contaminated wastewaters on the microbial community of a river,"The influence of chromium on the microbial community structure was analyzed in a river system subjected to long-term chromium contamination, by plating and by sequencing 16S rRNA genes cloned from DNA extracted from the river sediments. We also analyzed the influence of chromium on the ability of the microbial community to resist and reduce Cr(VI) and on its resistance to antibiotics. Shifts in the microbial community structure were analyzed by amplified ribosomal DNA restriction analysis fingerprinting. The isolates obtained were phylogenetically related to Actinobacteria, Firmicutes, Bacteroidetes and Proteobacteria, whereas Acidobacteria and Deltaproteobacteria were only revealed by clone analyses. Cr(VI)-resistant and Cr(VI)-reducing strains were isolated in all sites examined. However, each sample site had a microbial community with a different antibiotic resistance pattern. Our study seems to indicate that in this river ecosystem chromium influenced the microbial communities, altering some of their functional characteristics, such as the percentage of the microbial community able to resist or to reduce Cr(VI) and the phylogenetic groups isolated, but it did not affect the structural diversity. Furthermore, the concentration of Cr(VI) in the sediments could not be correlated with a lower number of bacteria or lower index of generic diversity, neither with the ability of the microbial community to resist or to reduce higher Cr(VI) concentrations.","Impact of chromium-contaminated wastewaters on the microbial community of a river Abs: The influence of chromium on the microbial community structure was analyzed in a river system subjected to long-term chromium contamination, by plating and by sequencing 16S rRNA genes cloned from DNA extracted from the river sediments. We also analyzed the influence of chromium on the ability of the microbial community to resist and reduce Cr(VI) and on its resistance to antibiotics. Shifts in the microbial community structure were analyzed by amplified ribosomal DNA restriction analysis fingerprinting. The isolates obtained were phylogenetically related to Actinobacteria, Firmicutes, Bacteroidetes and Proteobacteria, whereas Acidobacteria and Deltaproteobacteria were only revealed by clone analyses. Cr(VI)-resistant and Cr(VI)-reducing strains were isolated in all sites examined. However, each sample site had a microbial community with a different antibiotic resistance pattern. Our study seems to indicate that in this river ecosystem chromium influenced the microbial communities, altering some of their functional characteristics, such as the percentage of the microbial community able to resist or to reduce Cr(VI) and the phylogenetic groups isolated, but it did not affect the structural diversity. Furthermore, the concentration of Cr(VI) in the sediments could not be correlated with a lower number of bacteria or lower index of generic diversity, neither with the ability of the microbial community to resist or to reduce higher Cr(VI) concentrations."
1509652,Allegretti et al. 2006,The role of higher polythionates in the reduction of chromium(VI) by Acidithiobacillus and Thiobacillus cultures,"In this paper, we report the chromium(VI) reduction by filtrates of Acidithiobacillus and Thiobacillus cultures. Chromium(VI) reduction by filtrates of A. ferrooxidans cultures under acidic conditions was higher than that observed for A. thiooxidans. However, at pH close to 7, chromium(VI) reduction by filtrates of T. thioparus cultures was as high as that by filtrates of A. thiooxidans cultures and much higher than that observed for A. ferrooxidans cultures at the same pH. The capability of these cultures to reduce chromium(VI) was associated specifically with the fraction of cultures (cells, sulphur and associated sulphur compounds) retained by filtration through a 0.45mum filter. In the fraction that comes from A. thiooxidans culture, polythionates (S(x)O(6)(2-)) with 3-7 sulphur atoms were detected and identified (by HPLC with MS as detector). The model of vesicles containing polythionates, sulphur and water agrees with our results.","The role of higher polythionates in the reduction of chromium(VI) by Acidithiobacillus and Thiobacillus cultures Abs: In this paper, we report the chromium(VI) reduction by filtrates of Acidithiobacillus and Thiobacillus cultures. Chromium(VI) reduction by filtrates of A. ferrooxidans cultures under acidic conditions was higher than that observed for A. thiooxidans. However, at pH close to 7, chromium(VI) reduction by filtrates of T. thioparus cultures was as high as that by filtrates of A. thiooxidans cultures and much higher than that observed for A. ferrooxidans cultures at the same pH. The capability of these cultures to reduce chromium(VI) was associated specifically with the fraction of cultures (cells, sulphur and associated sulphur compounds) retained by filtration through a 0.45mum filter. In the fraction that comes from A. thiooxidans culture, polythionates (S(x)O(6)(2-)) with 3-7 sulphur atoms were detected and identified (by HPLC with MS as detector). The model of vesicles containing polythionates, sulphur and water agrees with our results."
1509651,Memon et al. 2005,Preconcentration and separation of Cr(III) and Cr(VI) using sawdust as a sorbent,"A simple, inexpensive method based on solid-phase extraction (SPE) on sawdust from Cedrus deodera has been developed for speciation of Cr(III) and Cr(VI) in environmental water samples. Because different exchange capacities were observed for the two forms of chromium at different pH-Cr(III) was selectively retained at pH 3 to 4 whereas Cr(VI) was retained at pH 1-complete separation of the two forms of chromium is possible. Retained species were eluted with 2.5 mL 0.1 mol L(-1) HCl and 0.1 mol L(-1) NaOH. Detection limits of 0.05 and 0.04 microg mL(-1) were achieved for Cr(III) and Cr(VI), respectively, with enrichment factors of 100 and 80. Recovery was quantitative using 250 mL sample volume for Cr(III) and 200 mL for Cr(VI). Different kinetic and thermodynamic properties that affect sorption of the chromium species on the sawdust were also determined. Metal ion concentration was measured as the Cr(VI)-diphenylcarbazide complex by UV-visible spectroscopy. The method was successfully applied for speciation of chromium in environmental and industrial water samples.","Preconcentration and separation of Cr(III) and Cr(VI) using sawdust as a sorbent Abs: A simple, inexpensive method based on solid-phase extraction (SPE) on sawdust from Cedrus deodera has been developed for speciation of Cr(III) and Cr(VI) in environmental water samples. Because different exchange capacities were observed for the two forms of chromium at different pH-Cr(III) was selectively retained at pH 3 to 4 whereas Cr(VI) was retained at pH 1-complete separation of the two forms of chromium is possible. Retained species were eluted with 2.5 mL 0.1 mol L(-1) HCl and 0.1 mol L(-1) NaOH. Detection limits of 0.05 and 0.04 microg mL(-1) were achieved for Cr(III) and Cr(VI), respectively, with enrichment factors of 100 and 80. Recovery was quantitative using 250 mL sample volume for Cr(III) and 200 mL for Cr(VI). Different kinetic and thermodynamic properties that affect sorption of the chromium species on the sawdust were also determined. Metal ion concentration was measured as the Cr(VI)-diphenylcarbazide complex by UV-visible spectroscopy. The method was successfully applied for speciation of chromium in environmental and industrial water samples."
1509650,Geetha et al. 2005,Immunomodulatory effects of seabuckthorn (Hippophae rhamnoides L.) against chromium (VI) induced immunosuppression,"The present study reports the immunomodulatory effects of seabuckthorn (Hippophae rhamnoides L.) leaf extract on cellular and humoral immune response by studying delayed-type hypersensitivity response, IL-2, IL-4 and gamma-IFN levels and antibody titres in chromium-induced immunosuppressed animals. Oral feeding of chromium (30 mg/kg bw) significantly inhibited antibody production and S-RBC induced delayed-type hypersensitivity response. Administration of leaf extract (100 mg/kg bw) along with chromium significantly inhibited chromium-induced immunosuppression. To understand the immunomodulatory mechanism of leaf extract, in vitro studies were carried out using rat lymphocytes. Addition of chromium resulted in a significant decrease in lymphocyte size and increased ROS generation. The leaf extract of seabuckthorn significantly inhibited chromium-induced reactive oxygen species (ROS) generation and maintained the cell size identical to that of control cells. Chromium treatment markedly inhibited the mitochondrial transmembrane potential by larger lymphocytes in particular, while the leaf extract restored the same significantly. Chromium also inhibited significantly concanavalin A (ConA) induced IL-2, IL-4 and gamma-IFN production in rat lymphocytes. The leaf extract (100 microg/ml) alone stimulated IL-2 and gamma-IFN production even in the absence of ConA and also inhibited chromium-induced decline in IL-2 and gamma-IFN production but it did not change IL-4 production. These observations suggest that the leaf extract of seabuckthorn has significant immunomodulatory activity and specifically activates the cell-mediated immune response.","Immunomodulatory effects of seabuckthorn (Hippophae rhamnoides L.) against chromium (VI) induced immunosuppression Abs: The present study reports the immunomodulatory effects of seabuckthorn (Hippophae rhamnoides L.) leaf extract on cellular and humoral immune response by studying delayed-type hypersensitivity response, IL-2, IL-4 and gamma-IFN levels and antibody titres in chromium-induced immunosuppressed animals. Oral feeding of chromium (30 mg/kg bw) significantly inhibited antibody production and S-RBC induced delayed-type hypersensitivity response. Administration of leaf extract (100 mg/kg bw) along with chromium significantly inhibited chromium-induced immunosuppression. To understand the immunomodulatory mechanism of leaf extract, in vitro studies were carried out using rat lymphocytes. Addition of chromium resulted in a significant decrease in lymphocyte size and increased ROS generation. The leaf extract of seabuckthorn significantly inhibited chromium-induced reactive oxygen species (ROS) generation and maintained the cell size identical to that of control cells. Chromium treatment markedly inhibited the mitochondrial transmembrane potential by larger lymphocytes in particular, while the leaf extract restored the same significantly. Chromium also inhibited significantly concanavalin A (ConA) induced IL-2, IL-4 and gamma-IFN production in rat lymphocytes. The leaf extract (100 microg/ml) alone stimulated IL-2 and gamma-IFN production even in the absence of ConA and also inhibited chromium-induced decline in IL-2 and gamma-IFN production but it did not change IL-4 production. These observations suggest that the leaf extract of seabuckthorn has significant immunomodulatory activity and specifically activates the cell-mediated immune response."
1509649,Bayen et al. 2005,"Oxidation of D-glucose in the presence of 2,2'-bipyridine by CrVI in aqueous micellar media: a kinetic study","The kinetics of Cr(VI) oxidation of D-glucose to the corresponding lactone in the presence and absence of 2,2'-bipyridine (bipy) has been carried out under the conditions, [D-glucose](T) &gt; [Cr(VI)](T) at different temperatures in aqueous micellar media. The monomeric Cr(VI) species has been found to be kinetically active in the absence of bipy whereas in the bipy-catalysed path, the Cr(VI)-bipy complex has been found to be the active oxidant. In the bipy-catalysed path, the Cr(VI)-bipy complex undergoes nucleophilic attack by the substrate to form a ternary complex. The ternary complex spontaneously experiences a redox decomposition (through two-electron transfer) in the rate-determining step leading to the product lactone and Cr(IV)-bipy complex. The Cr(IV)-bipy complex then takes part in faster steps in the further oxidation of D-glucose and is ultimately converted into a Cr(III)-bipy complex. In the uncatalysed path, the Cr(VI)-substrate ester experiences acid catalysed redox decomposition (two-electron transfer) in the rate-determining step. The uncatalysed path shows a second order dependence on [H(+)] and a first order dependence on each of the reactants [D-glucose](T) and [Cr(VI)](T). In contrast, the bipy-catalysed path shows a first order dependence on each of the reactants [H(+)], [D-glucose](T) and [Cr(VI)](T). The bipy-catalysed path is first order in [bipy](T). These observations remain unaltered in the presence of externally added surfactants. The effect of the cationic surfactant, N-cetylpyridinium chloride (CPC) and anionic surfactant, sodium dodecyl sulfate (SDS) on both the uncatalysed and bipy-catalysed path has been studied. CPC inhibits both the uncatalysed and bipy-catalysed path, while SDS catalyses these reactions. The observed micellar effects have been explained by considering hydrophobic and electrostatic interactions between the surfactants and reactants.","Oxidation of D-glucose in the presence of 2,2'-bipyridine by CrVI in aqueous micellar media: a kinetic study Abs: The kinetics of Cr(VI) oxidation of D-glucose to the corresponding lactone in the presence and absence of 2,2'-bipyridine (bipy) has been carried out under the conditions, [D-glucose](T) &gt; [Cr(VI)](T) at different temperatures in aqueous micellar media. The monomeric Cr(VI) species has been found to be kinetically active in the absence of bipy whereas in the bipy-catalysed path, the Cr(VI)-bipy complex has been found to be the active oxidant. In the bipy-catalysed path, the Cr(VI)-bipy complex undergoes nucleophilic attack by the substrate to form a ternary complex. The ternary complex spontaneously experiences a redox decomposition (through two-electron transfer) in the rate-determining step leading to the product lactone and Cr(IV)-bipy complex. The Cr(IV)-bipy complex then takes part in faster steps in the further oxidation of D-glucose and is ultimately converted into a Cr(III)-bipy complex. In the uncatalysed path, the Cr(VI)-substrate ester experiences acid catalysed redox decomposition (two-electron transfer) in the rate-determining step. The uncatalysed path shows a second order dependence on [H(+)] and a first order dependence on each of the reactants [D-glucose](T) and [Cr(VI)](T). In contrast, the bipy-catalysed path shows a first order dependence on each of the reactants [H(+)], [D-glucose](T) and [Cr(VI)](T). The bipy-catalysed path is first order in [bipy](T). These observations remain unaltered in the presence of externally added surfactants. The effect of the cationic surfactant, N-cetylpyridinium chloride (CPC) and anionic surfactant, sodium dodecyl sulfate (SDS) on both the uncatalysed and bipy-catalysed path has been studied. CPC inhibits both the uncatalysed and bipy-catalysed path, while SDS catalyses these reactions. The observed micellar effects have been explained by considering hydrophobic and electrostatic interactions between the surfactants and reactants."
1509648,Min et al. 2005,Black shale as a sorbent for trichloroethylene and Cr(VI),"Black shale was examined as a natural sorbent for organic and inorganic contaminants. Trichloroethylene (TCE) could be removed well from the water by sorption onto the locally available black shale because of the high organic carbon content (5.2%) of the black shale in this study. Hexavalent chromium Cr(VI) was mainly removed by ionic sorption and reduction in batch and column experiments. Amphiphilic humic acid was also sorbed onto the black shale and could facilitate the sorption of TCE at the same time. Humic acid also enhanced the removal of Cr(VI) by reduction and sorption, but the amount of Cr(VI) adsorbed (mg kg(-1)) was smaller than that of TCE. Considering that the black shale in this study was used without any modifications and has a small surface area, black shale can be a cost-effective natural geosorbent and additive to remove organic contaminants and heavy metals.","Black shale as a sorbent for trichloroethylene and Cr(VI) Abs: Black shale was examined as a natural sorbent for organic and inorganic contaminants. Trichloroethylene (TCE) could be removed well from the water by sorption onto the locally available black shale because of the high organic carbon content (5.2%) of the black shale in this study. Hexavalent chromium Cr(VI) was mainly removed by ionic sorption and reduction in batch and column experiments. Amphiphilic humic acid was also sorbed onto the black shale and could facilitate the sorption of TCE at the same time. Humic acid also enhanced the removal of Cr(VI) by reduction and sorption, but the amount of Cr(VI) adsorbed (mg kg(-1)) was smaller than that of TCE. Considering that the black shale in this study was used without any modifications and has a small surface area, black shale can be a cost-effective natural geosorbent and additive to remove organic contaminants and heavy metals."
1509647,Slade et al. 2005,Guanine-specific oxidation of double-stranded DNA by Cr(VI) and ascorbic acid forms spiroiminodihydantoin and 8-oxo-2'-deoxyguanosine,"7,8-dihydro-8-oxoguanine (8-oxoG) is thought to be a major lesion formed in DNA by oxidative attack at the nucleobase guanine. Recent studies have shown that 8-oxoG has a lower reduction potential than the parent guanine and is a hot spot for further oxidation. Spiroiminodihydantoin (Sp) has been identified as one of these further oxidation products. Chromium(VI) is a human carcinogen that, when reduced by a cellular reductant such as ascorbate, can oxidize DNA. In this study, duplex DNA was reacted with Cr(VI) and ascorbate to identify and quantify the base lesions formed. Guanine bases were observed to be preferentially oxidized with 5' guanines within purine repeats showing enhanced oxidation. Trapping of the guanine lesions by the base excision repair enzymes hOGG1 and mNEIL2 showed nearly exclusive trapping by mNEIL2, suggesting that 8-oxoG was not the major lesion but rather a lesion recognized by mNEIL2 such as Sp. Formation of the Sp lesion in the Cr(VI)/Asc oxidation reaction with DNA was confirmed by LC-ESI-MS detection. HPLC-ECD was used to identify and quantify any 8-oxoG arising from Cr(VI)/Asc oxidation of DNA. Concentrations of Cr(VI) (3.1-50 microM) with a corresponding 1:10 ratio of Asc oxidized between 0.3% and 1.5% of all guanines within the duplex DNA strand to Sp. 8-oxoG was also identified but with the highest Cr(VI) concentration converting approximately 0.1% of all guanines to 8-oxoG. These results show that Sp was present in concentrations approximately 20 times greater than that of 8-oxoG in this system. The results indicate that 8-oxoG, while present, was not the major product of Cr(VI)/Asc oxidation of DNA and that Sp predominates under these conditions. These results further imply that Sp may be the lesion that accounts for the carcinogenicity of this metal in cellular systems.","Guanine-specific oxidation of double-stranded DNA by Cr(VI) and ascorbic acid forms spiroiminodihydantoin and 8-oxo-2'-deoxyguanosine Abs: 7,8-dihydro-8-oxoguanine (8-oxoG) is thought to be a major lesion formed in DNA by oxidative attack at the nucleobase guanine. Recent studies have shown that 8-oxoG has a lower reduction potential than the parent guanine and is a hot spot for further oxidation. Spiroiminodihydantoin (Sp) has been identified as one of these further oxidation products. Chromium(VI) is a human carcinogen that, when reduced by a cellular reductant such as ascorbate, can oxidize DNA. In this study, duplex DNA was reacted with Cr(VI) and ascorbate to identify and quantify the base lesions formed. Guanine bases were observed to be preferentially oxidized with 5' guanines within purine repeats showing enhanced oxidation. Trapping of the guanine lesions by the base excision repair enzymes hOGG1 and mNEIL2 showed nearly exclusive trapping by mNEIL2, suggesting that 8-oxoG was not the major lesion but rather a lesion recognized by mNEIL2 such as Sp. Formation of the Sp lesion in the Cr(VI)/Asc oxidation reaction with DNA was confirmed by LC-ESI-MS detection. HPLC-ECD was used to identify and quantify any 8-oxoG arising from Cr(VI)/Asc oxidation of DNA. Concentrations of Cr(VI) (3.1-50 microM) with a corresponding 1:10 ratio of Asc oxidized between 0.3% and 1.5% of all guanines within the duplex DNA strand to Sp. 8-oxoG was also identified but with the highest Cr(VI) concentration converting approximately 0.1% of all guanines to 8-oxoG. These results show that Sp was present in concentrations approximately 20 times greater than that of 8-oxoG in this system. The results indicate that 8-oxoG, while present, was not the major product of Cr(VI)/Asc oxidation of DNA and that Sp predominates under these conditions. These results further imply that Sp may be the lesion that accounts for the carcinogenicity of this metal in cellular systems."
1509646,Banks et al. 2006,Leaching and reduction of chromium in soil as affected by soil organic content and plants,"The oxidation state of chromium in contaminated soils is an important indicator of toxicity and potential mobility. Chromium in the hexavalent state is highly toxic and soluble, whereas the trivalent state is much less toxic and relatively insoluble. A laboratory study investigated the impact of growing plants and supplemental organic matter on chromium transport in soil. Plants alone had no appreciable effect on the chromium oxidation state in soil. Soil columns with higher organic content were associated with lower ratios of chromate:total chromium than the columns with lower organic matter. Analyses of column leachate, plant biomass, and soil indicate that more chromium leaching occurred in the vegetated, low organic columns. Retention of Cr in the soils was correlated to the Cr(III) content. Plant uptake of chromium accounted for less than 1% of the chromium removed from the soil. Overall, the addition of organic matter had the strongest influence on chromium mobility.","Leaching and reduction of chromium in soil as affected by soil organic content and plants Abs: The oxidation state of chromium in contaminated soils is an important indicator of toxicity and potential mobility. Chromium in the hexavalent state is highly toxic and soluble, whereas the trivalent state is much less toxic and relatively insoluble. A laboratory study investigated the impact of growing plants and supplemental organic matter on chromium transport in soil. Plants alone had no appreciable effect on the chromium oxidation state in soil. Soil columns with higher organic content were associated with lower ratios of chromate:total chromium than the columns with lower organic matter. Analyses of column leachate, plant biomass, and soil indicate that more chromium leaching occurred in the vegetated, low organic columns. Retention of Cr in the soils was correlated to the Cr(III) content. Plant uptake of chromium accounted for less than 1% of the chromium removed from the soil. Overall, the addition of organic matter had the strongest influence on chromium mobility."
1509645,Hassan et al. 2005,A potentiometric rhodamine-B based membrane sensor for the selective determination of chromium ions in wastewater,"The construction and performance characteristics of a novel chromate ion-selective membrane sensor are described and used for determining chromium(III) and chromium(VI) ions. The sensor is based on the use of a rhodamine-B chromate ion-associate complex as an electroactive material in a poly(vinyl chloride) membrane plasticized with o-nitrophenyloctyl ether as a solvent mediator. In a phosphate buffer solution of pH 6 - 7, the sensor displays a stable, reproducible and linear potential response over the concentration range of 1 x 10(-1) - 5 x 10(-6) mol l(-1) with an anionic Nernstian slope of 30.8 +/- 0.5 mV decade(-1) and a detection limit of 1 x 10(-6) mol l(-1) Cr(VI). High selectivity for Cr(VI) is offered over many common anions (e.g., I-, Br-, Cl-, IO4-, CN-, acetate, oxalate, citrate, sulfate, phosphate, thiosulfate, selenite, nitrate) and cations (e.g., Ag+, Ca2+, Sr2+, Co2+, Ni2+, Cu2+, Mn2+, Fe2+, Zn2+, Cd2+, Al3+, Cr3+). The sensor is used for determining Cr(VI) and/or Cr(III) ions in separate or mixed solutions after the oxidation of Cr(III) into Cr(VI) with H2O2. As low as 0.2 microg ml(-1) of chromium is determined with a precision of +/-1.2%. The chromium contents of some wastewater samples were accurately assessed, and the results agreed fairly well with data obtained by atomic absorption spectrometry.","A potentiometric rhodamine-B based membrane sensor for the selective determination of chromium ions in wastewater Abs: The construction and performance characteristics of a novel chromate ion-selective membrane sensor are described and used for determining chromium(III) and chromium(VI) ions. The sensor is based on the use of a rhodamine-B chromate ion-associate complex as an electroactive material in a poly(vinyl chloride) membrane plasticized with o-nitrophenyloctyl ether as a solvent mediator. In a phosphate buffer solution of pH 6 - 7, the sensor displays a stable, reproducible and linear potential response over the concentration range of 1 x 10(-1) - 5 x 10(-6) mol l(-1) with an anionic Nernstian slope of 30.8 +/- 0.5 mV decade(-1) and a detection limit of 1 x 10(-6) mol l(-1) Cr(VI). High selectivity for Cr(VI) is offered over many common anions (e.g., I-, Br-, Cl-, IO4-, CN-, acetate, oxalate, citrate, sulfate, phosphate, thiosulfate, selenite, nitrate) and cations (e.g., Ag+, Ca2+, Sr2+, Co2+, Ni2+, Cu2+, Mn2+, Fe2+, Zn2+, Cd2+, Al3+, Cr3+). The sensor is used for determining Cr(VI) and/or Cr(III) ions in separate or mixed solutions after the oxidation of Cr(III) into Cr(VI) with H2O2. As low as 0.2 microg ml(-1) of chromium is determined with a precision of +/-1.2%. The chromium contents of some wastewater samples were accurately assessed, and the results agreed fairly well with data obtained by atomic absorption spectrometry."
1509644,Chaudhary et al. 2006,The regeneration and recycle of chromium etching solutions using concentrator cell membrane technology,The regeneration of chromium (VI) and the recovery of etched copper from chromium etching solutions by electrodialysis is improved by the addition of a concentrator cell in the catholyte chamber. The concentrator media used are ion-exchange resins or activated carbon cloth. The maximum percentages for the regeneration of chromium and recovery of copper in these systems is however less than 80% and 90% respectively because of the competition between the processes of oxidation of Cr(III) and electrodeposition of copper. A novel combination of electrolysis with electrodialysis and concentrator cell technology is developed that achieves 92% chromium regeneration and 90% copper recovery.,The regeneration and recycle of chromium etching solutions using concentrator cell membrane technology Abs: The regeneration of chromium (VI) and the recovery of etched copper from chromium etching solutions by electrodialysis is improved by the addition of a concentrator cell in the catholyte chamber. The concentrator media used are ion-exchange resins or activated carbon cloth. The maximum percentages for the regeneration of chromium and recovery of copper in these systems is however less than 80% and 90% respectively because of the competition between the processes of oxidation of Cr(III) and electrodeposition of copper. A novel combination of electrolysis with electrodialysis and concentrator cell technology is developed that achieves 92% chromium regeneration and 90% copper recovery.
1509643,Faisal et al. 2005,Chromium-resistant bacteria and cyanobacteria: impact on Cr(VI) reduction potential and plant growth,"Two chromium-resistant bacterial strains, Bacillus cereus S-6 and Ochrobactrum intermedium CrT-1, and two cyanobacterial strains, Oscillatoria sp. and Synechocystis sp., were used in this study. At initial chromate concentrations of 300 and 600 microg K2CrO4 mL(-1), and an inoculum size of 9.6 x 10(7) cells mL(-1), B. cereus S-6 completely reduced Cr(VI), while O. intermedium CrT-1 reduced Cr(VI) by 98% and 70%, respectively after 96 h. At 100 microg K2CrO4 mL(-1), Synechocystis sp. MK(S) and Oscillatoria sp. BJ2 reduced 62.1% and 39.9% of Cr(VI), respectively, at 30 degrees C and pH 8. Application of hexavalent chromate salts adversely affected wheat seedling growth and anatomical characters. However, bacterial inoculation alleviated the toxic effects, as reflected by significant improvements in growth as well as anatomical parameters. Cyanobacterial strains also led to some enhancement of various growth parameters in wheat seedlings.","Chromium-resistant bacteria and cyanobacteria: impact on Cr(VI) reduction potential and plant growth Abs: Two chromium-resistant bacterial strains, Bacillus cereus S-6 and Ochrobactrum intermedium CrT-1, and two cyanobacterial strains, Oscillatoria sp. and Synechocystis sp., were used in this study. At initial chromate concentrations of 300 and 600 microg K2CrO4 mL(-1), and an inoculum size of 9.6 x 10(7) cells mL(-1), B. cereus S-6 completely reduced Cr(VI), while O. intermedium CrT-1 reduced Cr(VI) by 98% and 70%, respectively after 96 h. At 100 microg K2CrO4 mL(-1), Synechocystis sp. MK(S) and Oscillatoria sp. BJ2 reduced 62.1% and 39.9% of Cr(VI), respectively, at 30 degrees C and pH 8. Application of hexavalent chromate salts adversely affected wheat seedling growth and anatomical characters. However, bacterial inoculation alleviated the toxic effects, as reflected by significant improvements in growth as well as anatomical parameters. Cyanobacterial strains also led to some enhancement of various growth parameters in wheat seedlings."
1509642,Pouzar et al. 2005,Derivatives of 16alpha-hydroxy-dehydroepiandrosterone with an additional 7-oxo or 7-hydroxy substituent: synthesis and gas chromatography/mass spectrometry analysis,"Derivatives of 16alpha-hydroxy-dehydroepiandrosterone, which have an additional oxygen substituent at position 7 (oxo or hydroxy group), were synthesized. Firstly, 17,17-dimethoxyandrost-5-ene-3beta,16alpha-diyl diacetate was prepared and then oxidized with a complex of chromium(VI) oxide and 2,5-dimethylpyrazole to the respective 7-oxo derivative. This key intermediate was both deprotected or reduced by l-Selectride or sodium borohydride in the presence of cerium(III) chloride and then deprotected to give 7-oxo, 7alpha-hydroxy and 7beta-hydroxy derivatives of 16alpha-hydroxy-dehydroepiandrosterone. The target compounds were characterized by (1)H and (13)C NMR spectra and in the form of O-methyloxime-trimethylsilyl derivatives, by gas chromatography/mass spectrometry methods.","Derivatives of 16alpha-hydroxy-dehydroepiandrosterone with an additional 7-oxo or 7-hydroxy substituent: synthesis and gas chromatography/mass spectrometry analysis Abs: Derivatives of 16alpha-hydroxy-dehydroepiandrosterone, which have an additional oxygen substituent at position 7 (oxo or hydroxy group), were synthesized. Firstly, 17,17-dimethoxyandrost-5-ene-3beta,16alpha-diyl diacetate was prepared and then oxidized with a complex of chromium(VI) oxide and 2,5-dimethylpyrazole to the respective 7-oxo derivative. This key intermediate was both deprotected or reduced by l-Selectride or sodium borohydride in the presence of cerium(III) chloride and then deprotected to give 7-oxo, 7alpha-hydroxy and 7beta-hydroxy derivatives of 16alpha-hydroxy-dehydroepiandrosterone. The target compounds were characterized by (1)H and (13)C NMR spectra and in the form of O-methyloxime-trimethylsilyl derivatives, by gas chromatography/mass spectrometry methods."
1509640,Bae et al. 2005,Purification and characterization of NADPH-dependent Cr(VI) reductase from Escherichia coli ATCC 33456,"A soluble Cr(VI) reductase was purified from the cytoplasm of Escherichia coli ATCC 33456. The molecular mass was estimated to be 84 and 42 kDa by gel filtration and SDS-polyacrylamide gel electrophoresis, respectively, indicating a dimeric structure. The pI was 4.66, and optimal enzyme activity was obtained at pH 6.5 and 37 degrees C. The most stable condition existed at pH 7.0. The purified enzyme used both NADPH and NADH as electron donors for Cr(VI) reduction, while NADPH was the better, conferring 61%; higher activity than NADH. The Km values for NADPH and NADH were determined to be 47.5 and 17.2 micromol, and the Vmax values 322.2 and 130.7 micromol Cr(VI) min(-1)mg(-1) protein, respectively. The activity was strongly inhibited by N-ethylmalemide, Ag2+, Cd2+, Hg2+, and Zn2+. The antibody against the enzyme showed no immunological cross reaction with those of other Cr(VI) reducing strains.","Purification and characterization of NADPH-dependent Cr(VI) reductase from Escherichia coli ATCC 33456 Abs: A soluble Cr(VI) reductase was purified from the cytoplasm of Escherichia coli ATCC 33456. The molecular mass was estimated to be 84 and 42 kDa by gel filtration and SDS-polyacrylamide gel electrophoresis, respectively, indicating a dimeric structure. The pI was 4.66, and optimal enzyme activity was obtained at pH 6.5 and 37 degrees C. The most stable condition existed at pH 7.0. The purified enzyme used both NADPH and NADH as electron donors for Cr(VI) reduction, while NADPH was the better, conferring 61%; higher activity than NADH. The Km values for NADPH and NADH were determined to be 47.5 and 17.2 micromol, and the Vmax values 322.2 and 130.7 micromol Cr(VI) min(-1)mg(-1) protein, respectively. The activity was strongly inhibited by N-ethylmalemide, Ag2+, Cd2+, Hg2+, and Zn2+. The antibody against the enzyme showed no immunological cross reaction with those of other Cr(VI) reducing strains."
1509639,Branco et al. 2004,Ochrobactrum tritici strain 5bvl1 - characterization of a Cr(VI)-resistant and Cr(VI)-reducing strain,"Bacterial strain 5bvl1, isolated from a chromium-contaminated wastewater treatment plant and identified as Ochrobactrum tritici, was resistant to a broad range of antibiotics, to Cr(VI), Ni(II), Co(II), Cd(II), and Zn(II), and was able to grow in the presence of 5% NaCl and within the pH range 4-10. Characterization showed that strain 5bvl1 could be considered a halotolerant and alkalitolerant microorganism resistant to high concentrations of Cr(VI). This strain was able to grow aerobically in up to 10 mmolxL(-1) Cr(VI). Cr(VI) resistance was independent of sulphate concentration. Under aerobic conditions strain 5bvl1 was also able to reduce high Cr(VI) concentrations (up to 1.7 mmolxL(-1)). Increasing concentrations of Cr(VI) in the medium lowered the growth rate of strain 5bv11 but the reduction in growth rate could not be directly correlated with the amount of Cr(VI) reduced. Unlike the type strain, which was only able to reduce Cr(VI), strain 5bvl1 was resistant to Cr(VI) and able to reduce it. Moreover, in strain 5bvl1, the rate and extent of Cr(VI)-reduction were higher than in the other strains of the genus Ochrobactrum. Ochrobactrum strain 5bvl1 resists high Cr(VI) concentrations and has a high Cr(VI)-reducing ability, making it a valuable tool in bioremediation.","Ochrobactrum tritici strain 5bvl1 - characterization of a Cr(VI)-resistant and Cr(VI)-reducing strain Abs: Bacterial strain 5bvl1, isolated from a chromium-contaminated wastewater treatment plant and identified as Ochrobactrum tritici, was resistant to a broad range of antibiotics, to Cr(VI), Ni(II), Co(II), Cd(II), and Zn(II), and was able to grow in the presence of 5% NaCl and within the pH range 4-10. Characterization showed that strain 5bvl1 could be considered a halotolerant and alkalitolerant microorganism resistant to high concentrations of Cr(VI). This strain was able to grow aerobically in up to 10 mmolxL(-1) Cr(VI). Cr(VI) resistance was independent of sulphate concentration. Under aerobic conditions strain 5bvl1 was also able to reduce high Cr(VI) concentrations (up to 1.7 mmolxL(-1)). Increasing concentrations of Cr(VI) in the medium lowered the growth rate of strain 5bv11 but the reduction in growth rate could not be directly correlated with the amount of Cr(VI) reduced. Unlike the type strain, which was only able to reduce Cr(VI), strain 5bvl1 was resistant to Cr(VI) and able to reduce it. Moreover, in strain 5bvl1, the rate and extent of Cr(VI)-reduction were higher than in the other strains of the genus Ochrobactrum. Ochrobactrum strain 5bvl1 resists high Cr(VI) concentrations and has a high Cr(VI)-reducing ability, making it a valuable tool in bioremediation."
1509638,Bajda 2005,"Chromatite Ca[CrO4] in soil polluted with electroplating effluents (Zabierzów, Poland)","Chromatite, Ca[CrO(4)] (space group I41/amd), was found as yellow precipitates between the particles of soil, heavily polluted with chromium(VI)-bearing electroplating effluents and weathered subsoil rocks (marly limestones, marls). X-ray diffraction (XRD), infrared spectroscopy (IR) and scanning electron microscopy (SEM) have showed the precipitates to be almost pure Ca[CrO(4)]. The chromatite occurs mainly as coatings 5-30 microm large and prismatic grains 20-100 microm long. It was formed and preserved due to dissolution of calcium carbonate by electroplating effluents containing Cr(VI). Although precipitation of calcium chromates in the soils polluted with chromium(VI) compounds has already been mentioned in the literature, the author gives the first mineralogical description of the chromatite formed in such an environment.","Chromatite Ca[CrO4] in soil polluted with electroplating effluents (Zabierzów, Poland) Abs: Chromatite, Ca[CrO(4)] (space group I41/amd), was found as yellow precipitates between the particles of soil, heavily polluted with chromium(VI)-bearing electroplating effluents and weathered subsoil rocks (marly limestones, marls). X-ray diffraction (XRD), infrared spectroscopy (IR) and scanning electron microscopy (SEM) have showed the precipitates to be almost pure Ca[CrO(4)]. The chromatite occurs mainly as coatings 5-30 microm large and prismatic grains 20-100 microm long. It was formed and preserved due to dissolution of calcium carbonate by electroplating effluents containing Cr(VI). Although precipitation of calcium chromates in the soils polluted with chromium(VI) compounds has already been mentioned in the literature, the author gives the first mineralogical description of the chromatite formed in such an environment."
1509637,Van Beelen et al. 2004,Location-specific ecotoxicological risk assessment of metal-polluted soils,"When chemical analysis indicates metal pollution, a second-tier method is needed to evaluate whether toxic effects occur at the polluted sites. A method based on pollution-induced community tolerance (PICT) was developed using samples taken from locations polluted with sewage more than 20 years ago. Microorganisms extracted from soil samples were exposed to a concentration range of zinc, nickel, copper, chromium (III), or chromium (VI) salts in a buffer suspension. The remaining activity of the intoxicated microorganisms was determined by color formation with 31 different organic substrates in microtiter plates. Microorganisms from moderately Zn-polluted sites (&gt;45 mg/kg) showed an increased tolerance for zinc. Nickel tolerance was observed at 51 mg Ni/kg soil, chromium (VI) tolerance at 923 mg Cr/kg. In most cases, tolerance also was observed at higher concentrations. High concentrations of 1,494 mg Cu/kg or 3,935 mg Cr/kg did not show PICT, indicating a limited bioavailability of Cu and Cr at these sites. The benefits of our method are its greater sensitivity compared to other tests used at these sites, and its specificity for those metals that exceed allowable levels.","Location-specific ecotoxicological risk assessment of metal-polluted soils Abs: When chemical analysis indicates metal pollution, a second-tier method is needed to evaluate whether toxic effects occur at the polluted sites. A method based on pollution-induced community tolerance (PICT) was developed using samples taken from locations polluted with sewage more than 20 years ago. Microorganisms extracted from soil samples were exposed to a concentration range of zinc, nickel, copper, chromium (III), or chromium (VI) salts in a buffer suspension. The remaining activity of the intoxicated microorganisms was determined by color formation with 31 different organic substrates in microtiter plates. Microorganisms from moderately Zn-polluted sites (&gt;45 mg/kg) showed an increased tolerance for zinc. Nickel tolerance was observed at 51 mg Ni/kg soil, chromium (VI) tolerance at 923 mg Cr/kg. In most cases, tolerance also was observed at higher concentrations. High concentrations of 1,494 mg Cu/kg or 3,935 mg Cr/kg did not show PICT, indicating a limited bioavailability of Cu and Cr at these sites. The benefits of our method are its greater sensitivity compared to other tests used at these sites, and its specificity for those metals that exceed allowable levels."
1509636,Stridsklev et al. 2004,Monitoring of chromium and nickel in biological fluids of stainless steel welders using the flux-cored-wire (FCW) welding method,"<strong>OBJECTIVE: </strong>This study was undertaken to investigate the exposure to chromium (Cr) and nickel (Ni) in flux-cored wire (FCW) welders welding on stainless steel (SS).<br /><br /><strong>METHOD/DESIGN: </strong>Seven FCW welders were monitored for 3 days to 1 workweek, measuring Cr and Ni in air, blood, and urine. The welders were questioned about exposure to Cr and Ni during their whole working careers, with emphasis on the week of monitoring, about the use of personal protective equipment and their smoking habits.<br /><br /><strong>RESULTS: </strong>The air concentrations were mean 200 microg/m(3) (range 2.4-2,744) for total Cr, 11.3 microg/m(3) (&lt;0.2-151.3) for Cr(VI), and 50.4 microg/m(3) (&lt;2.0-416.7) for Ni during the workdays for the five welders who were monitored with air measurements. The levels of Cr and Ni in biological fluids varied between different workplaces. For Cr in whole blood, plasma, and erythrocytes, the mean levels after work were 1.25 (&lt;0.4-8.3) and 1.68 (&lt;0.2-8.0) and 0.9 (&lt;0.4-7.2) microg/l, respectively. For Ni most of the measurements in whole blood and plasma were below the detection limits, the mean levels after work being 0.84 (&lt;0.8-3.3) and 0.57 microg/l (&lt;0.4-1.7), respectively. Mean levels for Cr and Ni in the urine after work were 3.96 (0.34-40.7) and 2.50 (0.56-5.0) microg/g creatinine, respectively.<br /><br /><strong>CONCLUSION: </strong>Correlations between the Cr(VI) levels measured in air and the levels of total Cr in the measured biological fluids were found. The results seem to support the view that monitoring of Cr in the urine may be versatile for indirect monitoring of the Cr(VI) air level in FCW welders. The results seem to suggest that external and internal exposure to Cr and Ni in FCW welders welding SS is low in general.","Monitoring of chromium and nickel in biological fluids of stainless steel welders using the flux-cored-wire (FCW) welding method Abs: <strong>OBJECTIVE: </strong>This study was undertaken to investigate the exposure to chromium (Cr) and nickel (Ni) in flux-cored wire (FCW) welders welding on stainless steel (SS).<br /><br /><strong>METHOD/DESIGN: </strong>Seven FCW welders were monitored for 3 days to 1 workweek, measuring Cr and Ni in air, blood, and urine. The welders were questioned about exposure to Cr and Ni during their whole working careers, with emphasis on the week of monitoring, about the use of personal protective equipment and their smoking habits.<br /><br /><strong>RESULTS: </strong>The air concentrations were mean 200 microg/m(3) (range 2.4-2,744) for total Cr, 11.3 microg/m(3) (&lt;0.2-151.3) for Cr(VI), and 50.4 microg/m(3) (&lt;2.0-416.7) for Ni during the workdays for the five welders who were monitored with air measurements. The levels of Cr and Ni in biological fluids varied between different workplaces. For Cr in whole blood, plasma, and erythrocytes, the mean levels after work were 1.25 (&lt;0.4-8.3) and 1.68 (&lt;0.2-8.0) and 0.9 (&lt;0.4-7.2) microg/l, respectively. For Ni most of the measurements in whole blood and plasma were below the detection limits, the mean levels after work being 0.84 (&lt;0.8-3.3) and 0.57 microg/l (&lt;0.4-1.7), respectively. Mean levels for Cr and Ni in the urine after work were 3.96 (0.34-40.7) and 2.50 (0.56-5.0) microg/g creatinine, respectively.<br /><br /><strong>CONCLUSION: </strong>Correlations between the Cr(VI) levels measured in air and the levels of total Cr in the measured biological fluids were found. The results seem to support the view that monitoring of Cr in the urine may be versatile for indirect monitoring of the Cr(VI) air level in FCW welders. The results seem to suggest that external and internal exposure to Cr and Ni in FCW welders welding SS is low in general."
1509635,Dupont et al. 2004,Use of analytical microscopy to analyze the speciation of copper and chromium ions onto a low-cost biomaterial,"In this paper, we present our study of the speciation of copper and hexavalent chromium sorbed onto a lignocellulosic substrate, using analytical microscopy. The lignocellulosic substrate constitutes a low-cost biomaterial that can be used in wastewater treatment. Transmission electron microscopy (TEM) coupled with energy-dispersive X-ray spectroscopy (EDXS) was used to determine the speciation of the two metal ions on the constitutive moieties of the lignocellulosic substrate. The use of a staining agent sensitive to carbon unsaturation allowed us to differentiate between the microstructures rich in lignin entities and those rich in cellulose entities. The EDX analysis showed that metal ions are preferentially sorbed onto microstructures rich in lignin moieties. The energy electron loss spectroscopy (EELS) was used to determine the oxidation states of chromium in association with lignocellulosic moieties. We showed that the sorption process of hexavalent chromium requires the reduction of Cr(VI) into Cr(III) and the probable oxidation of lignin moieties.","Use of analytical microscopy to analyze the speciation of copper and chromium ions onto a low-cost biomaterial Abs: In this paper, we present our study of the speciation of copper and hexavalent chromium sorbed onto a lignocellulosic substrate, using analytical microscopy. The lignocellulosic substrate constitutes a low-cost biomaterial that can be used in wastewater treatment. Transmission electron microscopy (TEM) coupled with energy-dispersive X-ray spectroscopy (EDXS) was used to determine the speciation of the two metal ions on the constitutive moieties of the lignocellulosic substrate. The use of a staining agent sensitive to carbon unsaturation allowed us to differentiate between the microstructures rich in lignin entities and those rich in cellulose entities. The EDX analysis showed that metal ions are preferentially sorbed onto microstructures rich in lignin moieties. The energy electron loss spectroscopy (EELS) was used to determine the oxidation states of chromium in association with lignocellulosic moieties. We showed that the sorption process of hexavalent chromium requires the reduction of Cr(VI) into Cr(III) and the probable oxidation of lignin moieties."
1509634,Harper-Arabie et al. 2004,"Protective effects of allozyme genotype during chemical exposure in the grass shrimp, Palaemonetes pugio","The primary objective of this research was to determine if the genotype of the enzymes glucose phosphate isomerase (Gpi), phosphoglucomutase (Pgm), or mannose phosphate isomerase (Mpi) are factors affecting survival during acute endosulfan, fluoranthene, and chromium(VI) exposures. Palaemonetes pugio were exposed in the laboratory to 6.3 microg/L endosulfan, 100 mg/L chromium(VI), or 0.6 mg/L fluoranthene. Dead shrimp were removed at approximately 15-30 min intervals and the individual's genotypes for the Gpi, Mpi, and Pgm enzymes were determined. These data were used to establish whether allozyme genotype was related to tolerance as analyzed with non-parametric methods (i.e. development of survival curves using the Kaplan-Meier method of estimation) and parametric methods (i.e. proportional hazards models). Since the sex and/or size of the organism was expected to affect tolerance, these variables were accounted for in the proportional hazards models. Results indicated individuals that were heterozygous (MF) for the Gpi allozyme survived longer and had less overall mortality than the homozygous MM genotype when exposed to chromium(VI) and to fluoranthene. No allozyme genotypes were related to tolerance during the endosulfan exposure when sex was included as a covariate in the analysis. These results support the hypothesis that there is a genetic basis for tolerance in P. pugio during acute exposures to chromium(VI) and to fluoranthene. Although a relationship between Gpi genotype and contaminant tolerance has been identified in previous studies, no such relationship has been documented in P. pugio or with chromium(VI) as the contaminant.","Protective effects of allozyme genotype during chemical exposure in the grass shrimp, Palaemonetes pugio Abs: The primary objective of this research was to determine if the genotype of the enzymes glucose phosphate isomerase (Gpi), phosphoglucomutase (Pgm), or mannose phosphate isomerase (Mpi) are factors affecting survival during acute endosulfan, fluoranthene, and chromium(VI) exposures. Palaemonetes pugio were exposed in the laboratory to 6.3 microg/L endosulfan, 100 mg/L chromium(VI), or 0.6 mg/L fluoranthene. Dead shrimp were removed at approximately 15-30 min intervals and the individual's genotypes for the Gpi, Mpi, and Pgm enzymes were determined. These data were used to establish whether allozyme genotype was related to tolerance as analyzed with non-parametric methods (i.e. development of survival curves using the Kaplan-Meier method of estimation) and parametric methods (i.e. proportional hazards models). Since the sex and/or size of the organism was expected to affect tolerance, these variables were accounted for in the proportional hazards models. Results indicated individuals that were heterozygous (MF) for the Gpi allozyme survived longer and had less overall mortality than the homozygous MM genotype when exposed to chromium(VI) and to fluoranthene. No allozyme genotypes were related to tolerance during the endosulfan exposure when sex was included as a covariate in the analysis. These results support the hypothesis that there is a genetic basis for tolerance in P. pugio during acute exposures to chromium(VI) and to fluoranthene. Although a relationship between Gpi genotype and contaminant tolerance has been identified in previous studies, no such relationship has been documented in P. pugio or with chromium(VI) as the contaminant."
1509633,Al-Abadleh et al. 2004,Chromium(VI) binding to functionalized silica/water interfaces studied by nonlinear optical spectroscopy,Organic adlayers can significantly alter the interactions of environmentally relevant surfaces with their surroundings. We present the first second harmonic and broadband sum frequency generation (SHG and BBSFG) study that illustrates how organic surface functional groups can control the mobility of the priority pollutant chromium(VI) in soil: Cr(VI) binds to ester- and acid-functionalized surfaces but not to alkane-functionalized surfaces. The implications with respect to toxic metal transport across organic adlayers at liquid-solid interfaces are that aqueous Cr(VI) can be retained by polar groups common in biopolymers but not by hydrophobic groups common in surfactants.,Chromium(VI) binding to functionalized silica/water interfaces studied by nonlinear optical spectroscopy Abs: Organic adlayers can significantly alter the interactions of environmentally relevant surfaces with their surroundings. We present the first second harmonic and broadband sum frequency generation (SHG and BBSFG) study that illustrates how organic surface functional groups can control the mobility of the priority pollutant chromium(VI) in soil: Cr(VI) binds to ester- and acid-functionalized surfaces but not to alkane-functionalized surfaces. The implications with respect to toxic metal transport across organic adlayers at liquid-solid interfaces are that aqueous Cr(VI) can be retained by polar groups common in biopolymers but not by hydrophobic groups common in surfactants.
1509632,Kartvelishvili et al. 2004,Estimation of the cellular antioxidant response to chromium action using ESR method,"In the present study, the antioxidant capacity of chromium-treated L-41 (human epithelial-like cells) was investigated by the ESR spin-trapping technique. The crude cell extracts of the cells grown in the presence of 2 microM (nontoxic) and 20 microM (toxic) chromium (VI) concentrations were tested in the model Fenton system with and without catalase-inhibitor sodium azide. The presented approach using the ESR technique along with inhibitors lets us discern cell extract defense capacity connected with the enzymatic activity in viable cells and the catabolic activity in dying cells.","Estimation of the cellular antioxidant response to chromium action using ESR method Abs: In the present study, the antioxidant capacity of chromium-treated L-41 (human epithelial-like cells) was investigated by the ESR spin-trapping technique. The crude cell extracts of the cells grown in the presence of 2 microM (nontoxic) and 20 microM (toxic) chromium (VI) concentrations were tested in the model Fenton system with and without catalase-inhibitor sodium azide. The presented approach using the ESR technique along with inhibitors lets us discern cell extract defense capacity connected with the enzymatic activity in viable cells and the catabolic activity in dying cells."
1509631,Wang et al. 2004,Selective fluorescence determination of chromium(VI) with poly-4-vinylaninline nanoparticles,"The strong fluorescence poly-4-vinylaniline nanoparticles (PVN) has been prepared under ultrasonic radiation. Based on the fluorescence quenching of PVN by Cr(VI), a method for the selective determination of Cr(VI), without separation of Cr(III) in water, was developed. The reaction conditions between Cr(VI) and PVN were investigated in detail. The assay is characterized by short reaction time (&lt;1 min even at 0 degrees C temperature), very few interference stable fluorescence signals (at least 2.5 h), simple instrument (common spectrofluorometer) and simplicity (a one-step assay). Under optimal experimental conditions, a limit of detection of 0.02 microg ml(-1) was achieved. The calibration curve was linear over the concentration range 0.1-13.0 microg ml(-1) with a correlation coefficient of 0.9984. The proposed method has been applied to the selective quantification of Cr(VI) in synthetic samples and waste-water samples with the satisfactory results.","Selective fluorescence determination of chromium(VI) with poly-4-vinylaninline nanoparticles Abs: The strong fluorescence poly-4-vinylaniline nanoparticles (PVN) has been prepared under ultrasonic radiation. Based on the fluorescence quenching of PVN by Cr(VI), a method for the selective determination of Cr(VI), without separation of Cr(III) in water, was developed. The reaction conditions between Cr(VI) and PVN were investigated in detail. The assay is characterized by short reaction time (&lt;1 min even at 0 degrees C temperature), very few interference stable fluorescence signals (at least 2.5 h), simple instrument (common spectrofluorometer) and simplicity (a one-step assay). Under optimal experimental conditions, a limit of detection of 0.02 microg ml(-1) was achieved. The calibration curve was linear over the concentration range 0.1-13.0 microg ml(-1) with a correlation coefficient of 0.9984. The proposed method has been applied to the selective quantification of Cr(VI) in synthetic samples and waste-water samples with the satisfactory results."
1509630,Xu et al. 2004,Novel chromium(VI) catalyzed oxidation of N-alkylamides to imides with periodic acid,A novel and practical procedure for preparation of imides is described using chromium(VI) oxide to catalyze the oxidation of N-alkylamides with periodic acid in the presence of acetic anhydride in acetonitrile.,Novel chromium(VI) catalyzed oxidation of N-alkylamides to imides with periodic acid Abs: A novel and practical procedure for preparation of imides is described using chromium(VI) oxide to catalyze the oxidation of N-alkylamides with periodic acid in the presence of acetic anhydride in acetonitrile.
1509629,Katsiki et al. 2004,Alterations of senescence biomarkers in human cells by exposure to CrVI in vivo and in vitro,"Heavy metals like CrVI, CdII, PbII and SnII have many applications in industry. They also represent a group of labour pollutants, as they are involved in several physiological disorders, such as carcinogenesis and various tissue dysfunctions. However, limited knowledge exists regarding their effects on ageing. In the current work we provide evidence that workers chronically exposed to CrVI have considerably reduced serum levels of the biomarker of senescence and cell survival, Apolipoprotein J/Clusterin (ApoJ/CLU). Moreover, we have found that both the degree and the time of exposure to CrVI associate negatively with ApoJ/CLU serum levels. To further examine whether CrVI directly affects cellular senescence we treated for 10 weeks two adult skin fibroblasts cultures as well as embryonic fibroblasts with a range of CrVI concentrations that approximate the values recorded in the blood circulation of exposed workers. Cellular treatment with a CrVI concentration that approximates the highest concentration in the blood was extremely toxic and nearly all cells died immediately after the first treatment. Interestingly, continuous treatment with a 10-fold lower CrVI concentration resulted in the induction of premature senescence. More specifically, treated cells were growth arrested, acquired an irregular shape, were positive to beta-galactosidase staining, accumulated oxidized proteins and over-expressed the cyclin-dependent kinase inhibitor p21 and ApoJ/CLU. Similar treatments with three additional labour pollutants resulted in the induction of premature senescence by CdII, but not by SnII or PbII. In summary, our results indicate that exposure to CrVI induces alterations of senescence biomarkers both in vivo and in vitro. They also provide new valuable tools for monitoring CrVI cytotoxic effects in vivo as well as for re-evaluating the maximum permissive values of some labour pollutants, like CrVI and CdII.","Alterations of senescence biomarkers in human cells by exposure to CrVI in vivo and in vitro Abs: Heavy metals like CrVI, CdII, PbII and SnII have many applications in industry. They also represent a group of labour pollutants, as they are involved in several physiological disorders, such as carcinogenesis and various tissue dysfunctions. However, limited knowledge exists regarding their effects on ageing. In the current work we provide evidence that workers chronically exposed to CrVI have considerably reduced serum levels of the biomarker of senescence and cell survival, Apolipoprotein J/Clusterin (ApoJ/CLU). Moreover, we have found that both the degree and the time of exposure to CrVI associate negatively with ApoJ/CLU serum levels. To further examine whether CrVI directly affects cellular senescence we treated for 10 weeks two adult skin fibroblasts cultures as well as embryonic fibroblasts with a range of CrVI concentrations that approximate the values recorded in the blood circulation of exposed workers. Cellular treatment with a CrVI concentration that approximates the highest concentration in the blood was extremely toxic and nearly all cells died immediately after the first treatment. Interestingly, continuous treatment with a 10-fold lower CrVI concentration resulted in the induction of premature senescence. More specifically, treated cells were growth arrested, acquired an irregular shape, were positive to beta-galactosidase staining, accumulated oxidized proteins and over-expressed the cyclin-dependent kinase inhibitor p21 and ApoJ/CLU. Similar treatments with three additional labour pollutants resulted in the induction of premature senescence by CdII, but not by SnII or PbII. In summary, our results indicate that exposure to CrVI induces alterations of senescence biomarkers both in vivo and in vitro. They also provide new valuable tools for monitoring CrVI cytotoxic effects in vivo as well as for re-evaluating the maximum permissive values of some labour pollutants, like CrVI and CdII."
1509628,Oliveira et al. 2004,Glutathione protects heavy metal-induced inhibition of hepatic microsomal ethoxyresorufin O-deethylase activity in Dicentrarchus labrax L,"The in vitro effects of chromium (Cr(VI)), copper (Cu2+), iron (Fe2+), mercury (Hg2+), and zinc (Zn2+) were assessed on liver microsomal ethoxyresorufin O-deethylase (EROD) activity from a sea bass (Dicentrarchus labrax L.) preexposed under laboratory conditions to 2.7 microM beta-naphthoflavone. The reduced glutathione (GSH) protection potential against heavy metal effects was also studied. The heavy metal concentration ranges used for this study were as follows: 10 pM-5 mM Cr(VI), 10 pM-100 microM Cu2+, 10 pM-1 mM Fe2+, 10 pM-10 microM Hg2+, and 10 pM-100 microM Zn2+. Liver microsomal EROD activity was significantly inhibited after in vitro exposure to Cr(VI) (500 microM), Cu2+ (1 microM), Fe2+ (100 microM), Hg2+ (100 pM), and Zn2+ (10 microM). Heavy metals inhibitory effect on liver EROD activity was ordered as follows: Hg2+ &gt; Cu2+ &gt; Zn2+ &gt; Fe2+ &gt; Cr(VI). Protective effects against Hg2+ (1 and 10 microM), Cu2+ (1, 10, and 100 microM), and Zn2+ (10, 50, and 100 microM) were observed in the presence of 0.5 mM GSH by a decrease in liver microsomal EROD activity inhibition. However, 0.5 mM GSH did not protect liver microsomal EROD activity from Cr(VI), and Fe2+-induced inhibition. The effect of metal mixtures (Cu(2+) + Zn(2+), Zn(2+) + Fe(2+), Zn(2+) + Cr(VI), and Cr(VI) + Fe(2+)) (100 microM) on liver microsomal EROD activity was also assessed, revealing a synergistic interaction.","Glutathione protects heavy metal-induced inhibition of hepatic microsomal ethoxyresorufin O-deethylase activity in Dicentrarchus labrax L Abs: The in vitro effects of chromium (Cr(VI)), copper (Cu2+), iron (Fe2+), mercury (Hg2+), and zinc (Zn2+) were assessed on liver microsomal ethoxyresorufin O-deethylase (EROD) activity from a sea bass (Dicentrarchus labrax L.) preexposed under laboratory conditions to 2.7 microM beta-naphthoflavone. The reduced glutathione (GSH) protection potential against heavy metal effects was also studied. The heavy metal concentration ranges used for this study were as follows: 10 pM-5 mM Cr(VI), 10 pM-100 microM Cu2+, 10 pM-1 mM Fe2+, 10 pM-10 microM Hg2+, and 10 pM-100 microM Zn2+. Liver microsomal EROD activity was significantly inhibited after in vitro exposure to Cr(VI) (500 microM), Cu2+ (1 microM), Fe2+ (100 microM), Hg2+ (100 pM), and Zn2+ (10 microM). Heavy metals inhibitory effect on liver EROD activity was ordered as follows: Hg2+ &gt; Cu2+ &gt; Zn2+ &gt; Fe2+ &gt; Cr(VI). Protective effects against Hg2+ (1 and 10 microM), Cu2+ (1, 10, and 100 microM), and Zn2+ (10, 50, and 100 microM) were observed in the presence of 0.5 mM GSH by a decrease in liver microsomal EROD activity inhibition. However, 0.5 mM GSH did not protect liver microsomal EROD activity from Cr(VI), and Fe2+-induced inhibition. The effect of metal mixtures (Cu(2+) + Zn(2+), Zn(2+) + Fe(2+), Zn(2+) + Cr(VI), and Cr(VI) + Fe(2+)) (100 microM) on liver microsomal EROD activity was also assessed, revealing a synergistic interaction."
1509627,Kaszycki et al. 2004,Chromium accumulation by living yeast at various environmental conditions,"Yeast tolerance to Cr (III) and Cr (VI) as well as chromium accumulation potential were shown to depend on treatment time, metal concentration, biomass density and the phase of growth. Kinetic studies as exemplified by Pichia guilliermondii ATCC 201911 revealed a biphasic mode of Cr (III) uptake: a rapid sorption phase was followed by a slow process of accumulation, in which the contribution of the cell-bound Cr fraction increased, while the total cellular Cr level remained constant. Cr (VI) uptake was characterized by a time-dependent increase of total Cr and by a constant fractional contribution of the cell-adsorbed chromium, which suggests that the amount of cell-accumulated Cr also tended to increase over time. The resistance to Cr and metal accumulation levels were substantially elevated for a given strain when cultures were treated at high initial biomass densities (1 mg dry weight/ml) of exponentially proliferating cells. Maximum accumulation capabilities ranged between 4.0 and 13 mg Cr (III)/g dry weight and 2-6.7 mg Cr (VI)/g dry weight. The total cell-accumulated Cr contained 29.3% and 52.3% of organically bound chromium for the treatment of P. guilliermondii with Cr (III) and Cr (VI), respectively. Selected yeast strains, under specified physiological conditions, can be applied for bioremediation of environmental Cr contamination, and might be useful too for attempts to obtain chromium-enriched biomass containing biostabilized and nontoxic Cr forms for nutritional applications.","Chromium accumulation by living yeast at various environmental conditions Abs: Yeast tolerance to Cr (III) and Cr (VI) as well as chromium accumulation potential were shown to depend on treatment time, metal concentration, biomass density and the phase of growth. Kinetic studies as exemplified by Pichia guilliermondii ATCC 201911 revealed a biphasic mode of Cr (III) uptake: a rapid sorption phase was followed by a slow process of accumulation, in which the contribution of the cell-bound Cr fraction increased, while the total cellular Cr level remained constant. Cr (VI) uptake was characterized by a time-dependent increase of total Cr and by a constant fractional contribution of the cell-adsorbed chromium, which suggests that the amount of cell-accumulated Cr also tended to increase over time. The resistance to Cr and metal accumulation levels were substantially elevated for a given strain when cultures were treated at high initial biomass densities (1 mg dry weight/ml) of exponentially proliferating cells. Maximum accumulation capabilities ranged between 4.0 and 13 mg Cr (III)/g dry weight and 2-6.7 mg Cr (VI)/g dry weight. The total cell-accumulated Cr contained 29.3% and 52.3% of organically bound chromium for the treatment of P. guilliermondii with Cr (III) and Cr (VI), respectively. Selected yeast strains, under specified physiological conditions, can be applied for bioremediation of environmental Cr contamination, and might be useful too for attempts to obtain chromium-enriched biomass containing biostabilized and nontoxic Cr forms for nutritional applications."
1509626,Peña-Castro et al. 2004,Heavy metals removal by the microalga Scenedesmus incrassatulus in continuous cultures,"The microalga Scenedesmus incrassatulus was grown under continuous regime in the presence of chromium(VI), cadmium(II) and copper(II), as single metal species and as mixtures of two or three metals, in a laboratory scale system. We used an artificial wastewater with low free ion activities (as determined by MINEQL+) due to the presence of EDTA (a strong chelating agent) but with total concentrations not suitable for acceptable environments. Chromium(VI) and cadmium(II) had positive interaction that increased the removal percentages of both these metals; we could not, however, detect any interaction with copper(II). S. incrassatulus was able to remove all the tested metals to some extent (25-78%), but bivalent metals were not removed as efficiently as reported in batch cultures, probably due to the high pH values there recorded. Chromium(VI) was more efficiently removed in continuous cultures than in batch culture, because the uptake of chromate could be favored by actively growing algae.","Heavy metals removal by the microalga Scenedesmus incrassatulus in continuous cultures Abs: The microalga Scenedesmus incrassatulus was grown under continuous regime in the presence of chromium(VI), cadmium(II) and copper(II), as single metal species and as mixtures of two or three metals, in a laboratory scale system. We used an artificial wastewater with low free ion activities (as determined by MINEQL+) due to the presence of EDTA (a strong chelating agent) but with total concentrations not suitable for acceptable environments. Chromium(VI) and cadmium(II) had positive interaction that increased the removal percentages of both these metals; we could not, however, detect any interaction with copper(II). S. incrassatulus was able to remove all the tested metals to some extent (25-78%), but bivalent metals were not removed as efficiently as reported in batch cultures, probably due to the high pH values there recorded. Chromium(VI) was more efficiently removed in continuous cultures than in batch culture, because the uptake of chromate could be favored by actively growing algae."
1509625,Tang et al. 2004,Cloud point extraction for high-performance liquid chromatographic speciation of Cr(III) and Cr(VI) in aqueous solutions,"Cloud point extraction (CPE) was applied as a preconcentration step for HPLC speciation of chromium in aqueous solutions. Simultaneous preconcentration of Cr(III) and Cr(VI) in aqueous solutions was achieved by CPE with diethyldithiocarbamate (DDTC) as the chelating agent and Triton X-114 as the extractant. Baseline separation of the DDTC chelates of Cr(III) and Cr(VI) was realized on a RP-C18 column with the use of a mixture of methanol-water-acetonitrile (65:21:14, v/v) buffered with 0.05 M NaAc-HAc solution (pH 3.6) as the mobile phase at a flow rate of 1.0 ml min(-1). The precision (R.S.D.) for eight replicate injections of a mixture of 100 microg l(-1) of Cr(III) and Cr(VI) were 0.6 and 0.5% for the retention time, 4.1 and 4.6% for the peak area measurement, respectively. The concentration factor, which is defined as the concentration ratio of the analyte in the final diluted surfactant-rich extract ready for HPLC separation and in the initial solution, was 65 for Cr(III) and 19 for Cr(VI). The linear concentration range was from 50 to 1000 microg l(-1) for Cr(III) and 50-2000 microg l(-1) for Cr(VI). The detection limits of Cr(III) and Cr(VI) were 3.4 and 5.2 microg l(-1), respectively. The developed method was applied to the speciation of Cr(III) and Cr(VI) in snow water, river water, seawater and wastewater samples.","Cloud point extraction for high-performance liquid chromatographic speciation of Cr(III) and Cr(VI) in aqueous solutions Abs: Cloud point extraction (CPE) was applied as a preconcentration step for HPLC speciation of chromium in aqueous solutions. Simultaneous preconcentration of Cr(III) and Cr(VI) in aqueous solutions was achieved by CPE with diethyldithiocarbamate (DDTC) as the chelating agent and Triton X-114 as the extractant. Baseline separation of the DDTC chelates of Cr(III) and Cr(VI) was realized on a RP-C18 column with the use of a mixture of methanol-water-acetonitrile (65:21:14, v/v) buffered with 0.05 M NaAc-HAc solution (pH 3.6) as the mobile phase at a flow rate of 1.0 ml min(-1). The precision (R.S.D.) for eight replicate injections of a mixture of 100 microg l(-1) of Cr(III) and Cr(VI) were 0.6 and 0.5% for the retention time, 4.1 and 4.6% for the peak area measurement, respectively. The concentration factor, which is defined as the concentration ratio of the analyte in the final diluted surfactant-rich extract ready for HPLC separation and in the initial solution, was 65 for Cr(III) and 19 for Cr(VI). The linear concentration range was from 50 to 1000 microg l(-1) for Cr(III) and 50-2000 microg l(-1) for Cr(VI). The detection limits of Cr(III) and Cr(VI) were 3.4 and 5.2 microg l(-1), respectively. The developed method was applied to the speciation of Cr(III) and Cr(VI) in snow water, river water, seawater and wastewater samples."
1509624,Gardner and  Ravenscroft 1996,Determination of chromium(III) and total chromium in marine waters,"The development of an analytical technique is described which may be used to determine chromium, chromium(III) and chromium(VI) in estuarine and coastal waters. The method is based on selective micro-solvent extraction with subsequent GFAAS. The technique has been applied in a major North Sea estuary. The results obtained confirm that thermodynamic factors alone cannot be relied upon to describe the form of chromium in estuaries. Kinetic factors appear to have a strong influence over speciation and lead to the persistence of Cr(III) species in environments where Cr(VI) would be expected to be present.","Determination of chromium(III) and total chromium in marine waters Abs: The development of an analytical technique is described which may be used to determine chromium, chromium(III) and chromium(VI) in estuarine and coastal waters. The method is based on selective micro-solvent extraction with subsequent GFAAS. The technique has been applied in a major North Sea estuary. The results obtained confirm that thermodynamic factors alone cannot be relied upon to describe the form of chromium in estuaries. Kinetic factors appear to have a strong influence over speciation and lead to the persistence of Cr(III) species in environments where Cr(VI) would be expected to be present."
1509623,Timerbaev et al. 1996,Speciation studies by capillary electrophoresis- Simultaneous determination of chromium(III) and chromium(VI),"A method for the simultaneous determination of chromium(III) and chromium(VI) by capillary electrophoresis (CE) has been developed. The chromium(III) has been chelated with 1,2-cyclohexanediaminetetraacetic acid (CDTA) in order to impart a negative charge and similar mobility to both the chromium(III) and the chromium(VI) species. The effects of the amount of the reagent, pH and heating time required to complete the complexation have been studied. Factors affecting the CE behaviour such as the polarity of electrodes and the pH of electrophoretic buffer have been investigated. The separated species have been monitored by direct UV measurements at 214 nm. The detection limits achieved are 10 microg/l for Cr(VI) and 5 microg/l for Cr(III) and linear detector response is observed up to 100 mg/l. The procedure has been applied to the determination of both chromium species in industrial electroplating samples and its accuracy was checked by comparing the results (as total chromium) with those of atomic absorption spectrometry. No interference occurred from transition metal impurities under optimized separation conditions. The method is also shown to be feasible for determining Cr(III) as well as other metal ions capable to form complexes with CDTA (like iron(III), copper(II), zinc(II) and manganese(II)) in pharmaceutical preparations of essential trace elements.","Speciation studies by capillary electrophoresis- Simultaneous determination of chromium(III) and chromium(VI) Abs: A method for the simultaneous determination of chromium(III) and chromium(VI) by capillary electrophoresis (CE) has been developed. The chromium(III) has been chelated with 1,2-cyclohexanediaminetetraacetic acid (CDTA) in order to impart a negative charge and similar mobility to both the chromium(III) and the chromium(VI) species. The effects of the amount of the reagent, pH and heating time required to complete the complexation have been studied. Factors affecting the CE behaviour such as the polarity of electrodes and the pH of electrophoretic buffer have been investigated. The separated species have been monitored by direct UV measurements at 214 nm. The detection limits achieved are 10 microg/l for Cr(VI) and 5 microg/l for Cr(III) and linear detector response is observed up to 100 mg/l. The procedure has been applied to the determination of both chromium species in industrial electroplating samples and its accuracy was checked by comparing the results (as total chromium) with those of atomic absorption spectrometry. No interference occurred from transition metal impurities under optimized separation conditions. The method is also shown to be feasible for determining Cr(III) as well as other metal ions capable to form complexes with CDTA (like iron(III), copper(II), zinc(II) and manganese(II)) in pharmaceutical preparations of essential trace elements."
1509622,Yeh and  Jiang 2004,"Speciation of V, Cr and Fe by capillary electrophoresis-bandpass reaction cell inductively coupled plasma mass spectrometry","Capillary electrophoresis-dynamic reaction cell inductively coupled plasma mass spectrometry (CE-DRC-ICP-MS) for the speciation of iron(III/II), vanadium(V/IV) and chromium(VI/III) is described. Two different CE migration modes were employed for separating the six metal ions using pre-capillary complexation. One is counter-electroosmotic mode in which iron(III/II) and vanadium(V/IV) ions were well separated using a 60 cm x 75 microm i.d. fused silica capillary. The voltage was set at +22 kV and a 15 mmol l(-1) tris(hydroxymethyl)aminomethane (Tris) buffer (pH 8.75) containing 0.5 mmol l(-1) ethylenediaminetetraacetic acid (EDTA) and 0.5 mmol l(-1) ortho-phenanthroline (phen) was used as the electrophoretic buffer. The other is co-electroosmotic mode in which chromium(VI/III) ions were well separated while the applied voltage was set at -22 kV and a 10 mmol l(-1) ammonium citrate buffer (pH 7.7) containing 0.5 mmol l(-1) diethylenetriaminepentaacetic acid (DTPA) and 0.01% polybrene was used as the electrophoretic buffer. The mass spectra were measured at m/z 51, 52 and 56 for V. Cr and Fe, respectively. The interfering polyatomic ions of 35Cl16O+, 40Ar12C+ and 40Ar16O+ on 51V+, 52Cr+ and 56Fe+ determination were reduced in intensity significantly by using NH3 as the reaction cell gas in the DRC. The detection limits were in the range of 0.1-0.5, 0.4-1.3 and 1.2-1.7 ng ml(-1) for V, Cr and Fe, respectively. Applications of the method for the speciation of V, Cr and Fe in wastewater were demonstrated. The recoveries were in the range of 92-120% for various species.","Speciation of V, Cr and Fe by capillary electrophoresis-bandpass reaction cell inductively coupled plasma mass spectrometry Abs: Capillary electrophoresis-dynamic reaction cell inductively coupled plasma mass spectrometry (CE-DRC-ICP-MS) for the speciation of iron(III/II), vanadium(V/IV) and chromium(VI/III) is described. Two different CE migration modes were employed for separating the six metal ions using pre-capillary complexation. One is counter-electroosmotic mode in which iron(III/II) and vanadium(V/IV) ions were well separated using a 60 cm x 75 microm i.d. fused silica capillary. The voltage was set at +22 kV and a 15 mmol l(-1) tris(hydroxymethyl)aminomethane (Tris) buffer (pH 8.75) containing 0.5 mmol l(-1) ethylenediaminetetraacetic acid (EDTA) and 0.5 mmol l(-1) ortho-phenanthroline (phen) was used as the electrophoretic buffer. The other is co-electroosmotic mode in which chromium(VI/III) ions were well separated while the applied voltage was set at -22 kV and a 10 mmol l(-1) ammonium citrate buffer (pH 7.7) containing 0.5 mmol l(-1) diethylenetriaminepentaacetic acid (DTPA) and 0.01% polybrene was used as the electrophoretic buffer. The mass spectra were measured at m/z 51, 52 and 56 for V. Cr and Fe, respectively. The interfering polyatomic ions of 35Cl16O+, 40Ar12C+ and 40Ar16O+ on 51V+, 52Cr+ and 56Fe+ determination were reduced in intensity significantly by using NH3 as the reaction cell gas in the DRC. The detection limits were in the range of 0.1-0.5, 0.4-1.3 and 1.2-1.7 ng ml(-1) for V, Cr and Fe, respectively. Applications of the method for the speciation of V, Cr and Fe in wastewater were demonstrated. The recoveries were in the range of 92-120% for various species."
1509620,Pas et al. 2004,Uptake of chromium(III) and chromium(VI) compounds in the yeast cell structure,"The study presented in this article investigated the influence of different Cr(III) and Cr(VI) compounds in the cultivation medium on the uptake and localization of chromium in the cell structure of the yeast Candida intermedia. The morphology of the yeast cell surface was observed by the scanning electron microscopy. Results demonstrated that the growth inhibitory concentration of Cr(III) in the cultivation medium induced changes in the yeast cell shape and affected the budding pattern, while inhibitory concentration of Cr(VI) did not cause any visible effects on morphological properties of the yeast cells. The amount of total accumulated chromium in yeast cells and the distribution of chromium between the yeast cell walls and spheroplasts were determined by atomic absorption spectroscopy. No significant differences were found neither in total chromium accumulation nor in the distribution of chromium in yeast cell walls and spheroplasts between the two of Cr(VI) compounds. Conversely, substantial differences between Cr(III) compounds were demonstrated in the total uptake as well as the localization of chromium in yeast cells.","Uptake of chromium(III) and chromium(VI) compounds in the yeast cell structure Abs: The study presented in this article investigated the influence of different Cr(III) and Cr(VI) compounds in the cultivation medium on the uptake and localization of chromium in the cell structure of the yeast Candida intermedia. The morphology of the yeast cell surface was observed by the scanning electron microscopy. Results demonstrated that the growth inhibitory concentration of Cr(III) in the cultivation medium induced changes in the yeast cell shape and affected the budding pattern, while inhibitory concentration of Cr(VI) did not cause any visible effects on morphological properties of the yeast cells. The amount of total accumulated chromium in yeast cells and the distribution of chromium between the yeast cell walls and spheroplasts were determined by atomic absorption spectroscopy. No significant differences were found neither in total chromium accumulation nor in the distribution of chromium in yeast cell walls and spheroplasts between the two of Cr(VI) compounds. Conversely, substantial differences between Cr(III) compounds were demonstrated in the total uptake as well as the localization of chromium in yeast cells."
1509619,Viamajala et al. 2004,Toxic effects of chromium(VI) on anaerobic and aerobic growth of Shewanella oneidensis MR-1,"Cr(VI) was added to early- and mid-log-phase Shewanella oneidensis (S. oneidensis) MR-1 cultures to study the physiological state-dependent toxicity of Cr(VI). Cr(VI) reduction and culture growth were measured during and after Cr(VI) reduction. Inhibition of growth was observed when Cr(VI) was added to cultures of MR-1 growing aerobically or anaerobically with fumarate as the terminal electron acceptor. Under anaerobic conditions, there was immediate cessation of growth upon addition of Cr(VI) in early- and mid-log-phase cultures. However, once Cr(VI) was reduced below detection limits (0.002 mM), the cultures resumed growth with normal cell yield values observed. In contrast to anaerobic MR-1 cultures, addition of Cr(VI) to aerobically growing cultures resulted in a gradual decrease of the growth rate. In addition, under aerobic conditions, lower cell yields were also observed with Cr(VI)-treated cultures when compared to cultures that were not exposed to Cr(VI). Differences in response to Cr(VI) between aerobically and anaerobically growing cultures indicate that Cr(VI) toxicity in MR-1 is dependent on the physiological growth condition of the culture. Cr(VI) reduction has been previously studied in Shewanella spp., and it has been proposed that Shewanella spp. may be used in Cr(VI) bioremediation systems. Studies of Shewanella spp. provide valuable information on the microbial physiology of dissimilatory metal reducing bacteria; however, our study indicates that S. oneidensis MR-1 is highly susceptible to growth inhibition by Cr(VI) toxicity, even at low concentrations [0.015 mM Cr(VI)].","Toxic effects of chromium(VI) on anaerobic and aerobic growth of Shewanella oneidensis MR-1 Abs: Cr(VI) was added to early- and mid-log-phase Shewanella oneidensis (S. oneidensis) MR-1 cultures to study the physiological state-dependent toxicity of Cr(VI). Cr(VI) reduction and culture growth were measured during and after Cr(VI) reduction. Inhibition of growth was observed when Cr(VI) was added to cultures of MR-1 growing aerobically or anaerobically with fumarate as the terminal electron acceptor. Under anaerobic conditions, there was immediate cessation of growth upon addition of Cr(VI) in early- and mid-log-phase cultures. However, once Cr(VI) was reduced below detection limits (0.002 mM), the cultures resumed growth with normal cell yield values observed. In contrast to anaerobic MR-1 cultures, addition of Cr(VI) to aerobically growing cultures resulted in a gradual decrease of the growth rate. In addition, under aerobic conditions, lower cell yields were also observed with Cr(VI)-treated cultures when compared to cultures that were not exposed to Cr(VI). Differences in response to Cr(VI) between aerobically and anaerobically growing cultures indicate that Cr(VI) toxicity in MR-1 is dependent on the physiological growth condition of the culture. Cr(VI) reduction has been previously studied in Shewanella spp., and it has been proposed that Shewanella spp. may be used in Cr(VI) bioremediation systems. Studies of Shewanella spp. provide valuable information on the microbial physiology of dissimilatory metal reducing bacteria; however, our study indicates that S. oneidensis MR-1 is highly susceptible to growth inhibition by Cr(VI) toxicity, even at low concentrations [0.015 mM Cr(VI)]."
1509618,Vonderheide et al. 2004,Retention of Cr(III) by high-performance chelation ion chromatography interfaced to inductively-coupled plasma mass spectrometric detection with collision cell,"High-performance chelation ion chromatography (HPCIC) was employed to retain cationic Cr(III) on an anion-exchange column and hence allow the separation of the two most prevalent forms of chromium, Cr(II) and Cr(VI). A mobile phase of nitric acid was utilized at pH = 1.5; additionally, 2,6-pyridinedicarboxylic acid was used at a concentration of 6 mM. Additives with different structural characteristics were used in an effort to elucidate retention mechanisms. Inductively-coupled plasma mass spectrometry was used for chromium detection. A collision cell was utilized to reduce chloride-based polyatomic ions that may interfere with the detection of Cr(III), and a detection limit study yielded levels in the low part-per-billion range. The newly developed method was applied to the chromatographic analysis of samples of an incubation medium containing Cr(VI) incubated with cell nuclei.","Retention of Cr(III) by high-performance chelation ion chromatography interfaced to inductively-coupled plasma mass spectrometric detection with collision cell Abs: High-performance chelation ion chromatography (HPCIC) was employed to retain cationic Cr(III) on an anion-exchange column and hence allow the separation of the two most prevalent forms of chromium, Cr(II) and Cr(VI). A mobile phase of nitric acid was utilized at pH = 1.5; additionally, 2,6-pyridinedicarboxylic acid was used at a concentration of 6 mM. Additives with different structural characteristics were used in an effort to elucidate retention mechanisms. Inductively-coupled plasma mass spectrometry was used for chromium detection. A collision cell was utilized to reduce chloride-based polyatomic ions that may interfere with the detection of Cr(III), and a detection limit study yielded levels in the low part-per-billion range. The newly developed method was applied to the chromatographic analysis of samples of an incubation medium containing Cr(VI) incubated with cell nuclei."
1509617,Jamnik and  Raspor 2003,Stress response of yeast candida intermedia to Cr(VI),"Stress response of yeast Candida intermedia ZIM 156 exposed to chromium(VI) was investigated. Yeast cells were treated with Cr(VI) in concentrations of 50, 100, 300 and 500 microM in the mid-exponential growth phase. Monitoring of some bioprocess parameters during growth, specifically pO(2), showed that Cr(VI) addition, specifically in concentration of 100 and partially 50 micromol/L, increased metabolism intensity, which is connected to induced stress responses. Furthermore, oxidation of 2',7'-dichlorofluorescin indicated increased intracellular oxidant level, specifically at 100 microM Cr(VI) concentration. Antioxidant defense systems were further investigated. Catalase and superoxide dismutase activity was not increased in the cells exposed to the both Cr(VI) concentrations, which indicate that catalase and superoxide dismutase do not participate in cell defense systems. In contrast intracellular glutathione content in reduced form increased significantly in the cells exposed to 100 micromol Cr(VI)/L. Therefore, we demonstrated that glutathione plays an important role in the stress response of C. intermedia to Cr(VI).","Stress response of yeast candida intermedia to Cr(VI) Abs: Stress response of yeast Candida intermedia ZIM 156 exposed to chromium(VI) was investigated. Yeast cells were treated with Cr(VI) in concentrations of 50, 100, 300 and 500 microM in the mid-exponential growth phase. Monitoring of some bioprocess parameters during growth, specifically pO(2), showed that Cr(VI) addition, specifically in concentration of 100 and partially 50 micromol/L, increased metabolism intensity, which is connected to induced stress responses. Furthermore, oxidation of 2',7'-dichlorofluorescin indicated increased intracellular oxidant level, specifically at 100 microM Cr(VI) concentration. Antioxidant defense systems were further investigated. Catalase and superoxide dismutase activity was not increased in the cells exposed to the both Cr(VI) concentrations, which indicate that catalase and superoxide dismutase do not participate in cell defense systems. In contrast intracellular glutathione content in reduced form increased significantly in the cells exposed to 100 micromol Cr(VI)/L. Therefore, we demonstrated that glutathione plays an important role in the stress response of C. intermedia to Cr(VI)."
1509616,Ouejhani et al. 2003,Hexavalent chromium recovery by liquid-liquid extraction with tributylphosphate from acidic chloride media,"A method is introduced for recuperation of chromium(VI) in water samples by liquid-liquid extraction with tributylphosphate PO(C4H9O)3 (TBP) from acidic chloride media. The optimum conditions for quantitative extraction of Cr(VI) were evaluated by varying the experimental parameters, such as the shaking period, the pH of the aqueous phase, the hydrochloric acid concentration, the hydrogen and chloride ion concentrations, the extractant concentration and the ratio of aqueous-to-organic phase. The probable extracted species of hexavalent chromium in organic phase, deduced from log-log plots, were H2CrO4 in acid media in absence of chloride and HCrO3Cl in acidic chloride media. Chromium(VI) was found to be extracted with tributylphosphate from acidic chloride media according to the following reaction: HCrO4-(aq), + 2H+(aq) + Cl-(aq) + 2TBP(org) &lt;==&gt; [HCrO3Cl, 2TBP](org) + H2O(aq). Since the tributylphosphate (TBP) exhibited a high selectivity for chromium(VI), this method can be applicable to the extraction and the determination of chromium in both oxidation states [Cr(VI) and Cr(III)] in water samples.","Hexavalent chromium recovery by liquid-liquid extraction with tributylphosphate from acidic chloride media Abs: A method is introduced for recuperation of chromium(VI) in water samples by liquid-liquid extraction with tributylphosphate PO(C4H9O)3 (TBP) from acidic chloride media. The optimum conditions for quantitative extraction of Cr(VI) were evaluated by varying the experimental parameters, such as the shaking period, the pH of the aqueous phase, the hydrochloric acid concentration, the hydrogen and chloride ion concentrations, the extractant concentration and the ratio of aqueous-to-organic phase. The probable extracted species of hexavalent chromium in organic phase, deduced from log-log plots, were H2CrO4 in acid media in absence of chloride and HCrO3Cl in acidic chloride media. Chromium(VI) was found to be extracted with tributylphosphate from acidic chloride media according to the following reaction: HCrO4-(aq), + 2H+(aq) + Cl-(aq) + 2TBP(org) &lt;==&gt; [HCrO3Cl, 2TBP](org) + H2O(aq). Since the tributylphosphate (TBP) exhibited a high selectivity for chromium(VI), this method can be applicable to the extraction and the determination of chromium in both oxidation states [Cr(VI) and Cr(III)] in water samples."
1509615,Yang et al. 2003,Speciation of chromium by in-capillary reaction and capillary electrophoresis with chemiluminescence detection,"A sensitive method for the simultaneous determination of chromium(III) (Cr3+) and chromium(VI) (CrO4(2-)) using in-capillary reaction, capillary electrophoresis (CE) separation and chemiluminescence (CL) detection was developed. The chemiluminescence reaction was based on luminol oxidation by hydrogen peroxide in basic aqueous solution catalyzed by Cr3+ ion followed by capillary electrophoresis separation. Based on in-capillary reduction, chromium(VI) can be reduced by acidic sodium hydrogensulfite to form chromium(III) while the sample is running through the capillary. Before the electrophoresis procedure, the sample (Cr3+ and CrO4(2-)), buffer and acidic sodium hydrogensulfite solution segments were injected in that order into the capillary, followed by application of an appropriate running voltage between both ends. As both chromium species have opposite charges, Cr3+ ions migrate to the cathode, while CrO4(2-) ions, moving in the opposite direction toward the anode, react with acidic sodium hydrogensulfite which results in the formation of Cr3+ ions. Because of the migration time difference of both Cr3+ ions, Cr(III) and Cr(VI) could be separated. The running buffer was composed of 0.02 mol l(-1) acetate buffer (pH 4.7) with 1 x 10(-3) mol l(-1) EDTA. Parameters affecting CE-CL separation and detection, such as reductant (sodium hydrogensulfite) concentration, mixing mode of the analytes with CL reagent, CL reaction reagent pH and concentration, were optimized. The limits of detection (LODs) of Cr(III) and Cr(VI) were 6 x 10(-13) and 8 x 10(-12) mol l(-1) (S/N=3), respectively. The mass LODs for Cr(III) and Cr(VI) were 1.2 x 10(-20) mol (12 zmol) and 3.8 x 10(-19) mol (380 zmol), respectively.","Speciation of chromium by in-capillary reaction and capillary electrophoresis with chemiluminescence detection Abs: A sensitive method for the simultaneous determination of chromium(III) (Cr3+) and chromium(VI) (CrO4(2-)) using in-capillary reaction, capillary electrophoresis (CE) separation and chemiluminescence (CL) detection was developed. The chemiluminescence reaction was based on luminol oxidation by hydrogen peroxide in basic aqueous solution catalyzed by Cr3+ ion followed by capillary electrophoresis separation. Based on in-capillary reduction, chromium(VI) can be reduced by acidic sodium hydrogensulfite to form chromium(III) while the sample is running through the capillary. Before the electrophoresis procedure, the sample (Cr3+ and CrO4(2-)), buffer and acidic sodium hydrogensulfite solution segments were injected in that order into the capillary, followed by application of an appropriate running voltage between both ends. As both chromium species have opposite charges, Cr3+ ions migrate to the cathode, while CrO4(2-) ions, moving in the opposite direction toward the anode, react with acidic sodium hydrogensulfite which results in the formation of Cr3+ ions. Because of the migration time difference of both Cr3+ ions, Cr(III) and Cr(VI) could be separated. The running buffer was composed of 0.02 mol l(-1) acetate buffer (pH 4.7) with 1 x 10(-3) mol l(-1) EDTA. Parameters affecting CE-CL separation and detection, such as reductant (sodium hydrogensulfite) concentration, mixing mode of the analytes with CL reagent, CL reaction reagent pH and concentration, were optimized. The limits of detection (LODs) of Cr(III) and Cr(VI) were 6 x 10(-13) and 8 x 10(-12) mol l(-1) (S/N=3), respectively. The mass LODs for Cr(III) and Cr(VI) were 1.2 x 10(-20) mol (12 zmol) and 3.8 x 10(-19) mol (380 zmol), respectively."
1509614,Kwak et al. 2003,Vibrio harveyi nitroreductase is also a chromate reductase,"The chromate reductase purified from Pseudomonas ambigua was found to be homologous with several nitroreductases. Escherichia coli DH5alpha and Vibrio harveyi KCTC 2720 nitroreductases were chosen for the present study, and their chromate-reducing activities were determined. A fusion between glutathione S-transferase (GST) and E. coli DH5alpha NfsA (GST-EcNfsA), a fusion between GST and E. coli DH5alpha NfsB (GST-EcNfsB), and a fusion between GST and V. harveyi KCTC 2720 NfsA (GST-VhNfsA) were prepared for their overproduction and easy purification. GST-EcNfsA, GST-EcNFsB, and GST-VhNFsA efficiently reduced nitrofurazone and 2,4,6-trinitrotoluene (TNT) as their nitro substrates. The K(m) values for GST-EcNfsA, GST-EcNfsB, and GST-VhNfsA for chromate reduction were 11.8, 23.5, and 5.4 micro M, respectively. The V(max) values for GST-EcNfsA, GST-EcNfsB, and GST-VhNfsA were 3.8, 3.9, and 10.7 nmol/min/mg of protein, respectively. GST-VhNfsA was the most effective of the three chromate reductases, as determined by each V(max)/K(m) value. The optimal temperatures of GST-EcNfsA, GST-EcNfsB, and GST-VhNfsA for chromate reduction were 55, 30, and 30 degrees C, respectively. Thus, it is confirmed that nitroreductase can also act as a chromate reductase. Nitroreductases may be used in chromate remediation. GST-EcNfsA, GST-EcNfsB, and GST-VhNfsA have a molecular mass of 50 kDa and exist as a monomer in solution. Thin-layer chromatography showed that GST-EcNfsA, GST-EcNfsB, and GST-VhNfsA contain FMN as a cofactor. GST-VhNfsA reduced Cr(VI) to Cr(III). Cr(III) was much less toxic to E. coli than Cr(VI).","Vibrio harveyi nitroreductase is also a chromate reductase Abs: The chromate reductase purified from Pseudomonas ambigua was found to be homologous with several nitroreductases. Escherichia coli DH5alpha and Vibrio harveyi KCTC 2720 nitroreductases were chosen for the present study, and their chromate-reducing activities were determined. A fusion between glutathione S-transferase (GST) and E. coli DH5alpha NfsA (GST-EcNfsA), a fusion between GST and E. coli DH5alpha NfsB (GST-EcNfsB), and a fusion between GST and V. harveyi KCTC 2720 NfsA (GST-VhNfsA) were prepared for their overproduction and easy purification. GST-EcNfsA, GST-EcNFsB, and GST-VhNFsA efficiently reduced nitrofurazone and 2,4,6-trinitrotoluene (TNT) as their nitro substrates. The K(m) values for GST-EcNfsA, GST-EcNfsB, and GST-VhNfsA for chromate reduction were 11.8, 23.5, and 5.4 micro M, respectively. The V(max) values for GST-EcNfsA, GST-EcNfsB, and GST-VhNfsA were 3.8, 3.9, and 10.7 nmol/min/mg of protein, respectively. GST-VhNfsA was the most effective of the three chromate reductases, as determined by each V(max)/K(m) value. The optimal temperatures of GST-EcNfsA, GST-EcNfsB, and GST-VhNfsA for chromate reduction were 55, 30, and 30 degrees C, respectively. Thus, it is confirmed that nitroreductase can also act as a chromate reductase. Nitroreductases may be used in chromate remediation. GST-EcNfsA, GST-EcNfsB, and GST-VhNfsA have a molecular mass of 50 kDa and exist as a monomer in solution. Thin-layer chromatography showed that GST-EcNfsA, GST-EcNfsB, and GST-VhNfsA contain FMN as a cofactor. GST-VhNfsA reduced Cr(VI) to Cr(III). Cr(III) was much less toxic to E. coli than Cr(VI)."
1509613,Hursthouse et al. 2003,"Chromium in intertidal sediments of the Clyde, UK: potential for remobilisation and bioaccumulation","Detailed surveys of intertidal sediments have been performed along the north and south shores of the Inner Clyde estuary, UK. Surface sediment data reveal significant spatial variation in Cr content and an association with major sediment characteristics and location within the estuary. Depth variation for Cr and other heavy metals cannot be explained by variation in major geochemical controls such as grain size and organic matter and highlights the impact of historical contamination on sediment quality. These elevated levels at depth may still have environmental impact through redox-reactivity, in association with iron and manganese. Sequential extraction of sediments and pore water analysis of Cr(VI) and Cr(III) provide detailed information on release potential from the sediments. The implication of Cr mobility for biota in the estuary has been assessed by the analysis of a common marine bivalve, Mytilus edulis (Blue Mussel) and a burrowing polychaete, Nereis diversicolor (rag worm) from a number of survey sites. Bioconcentration factors for Mytilus indicate that the weakly held portion of sediment Cr is available for uptake and in the case of Nereis, bioaccumulation appears to be inhibited by sediment organic matter.","Chromium in intertidal sediments of the Clyde, UK: potential for remobilisation and bioaccumulation Abs: Detailed surveys of intertidal sediments have been performed along the north and south shores of the Inner Clyde estuary, UK. Surface sediment data reveal significant spatial variation in Cr content and an association with major sediment characteristics and location within the estuary. Depth variation for Cr and other heavy metals cannot be explained by variation in major geochemical controls such as grain size and organic matter and highlights the impact of historical contamination on sediment quality. These elevated levels at depth may still have environmental impact through redox-reactivity, in association with iron and manganese. Sequential extraction of sediments and pore water analysis of Cr(VI) and Cr(III) provide detailed information on release potential from the sediments. The implication of Cr mobility for biota in the estuary has been assessed by the analysis of a common marine bivalve, Mytilus edulis (Blue Mussel) and a burrowing polychaete, Nereis diversicolor (rag worm) from a number of survey sites. Bioconcentration factors for Mytilus indicate that the weakly held portion of sediment Cr is available for uptake and in the case of Nereis, bioaccumulation appears to be inhibited by sediment organic matter."
1509612,Ozdemir et al. 2003,Heavy metal biosorption by biomass of Ochrobactrum anthropi producing exopolysaccharide in activated sludge,"The removal of chromium, cadmium and copper, toxic metals of high environmental priority due to their toxicity, from dilute aqueous solutions has been studied in the present work, applying a dead exopolysaccharide producing bacterium, Ochrobactrum anthropi, isolated from activated sludge. Particularly, the effect of pH, metal concentration and the effects of contact time were considered. Optimum adsorption pH values of chromium(VI), cadmium(II) and copper(II) were 2.0, 8.0 and 3.0 respectively. Experimental results also showed the influence of initial metal concentration on the metal uptake for dried biomass. Both the Freundlich and Langmuir adsorption models were suitable for describing the short-term biosorption of chromium(VI), cadmium(II) and copper(II) by O. anthropi.","Heavy metal biosorption by biomass of Ochrobactrum anthropi producing exopolysaccharide in activated sludge Abs: The removal of chromium, cadmium and copper, toxic metals of high environmental priority due to their toxicity, from dilute aqueous solutions has been studied in the present work, applying a dead exopolysaccharide producing bacterium, Ochrobactrum anthropi, isolated from activated sludge. Particularly, the effect of pH, metal concentration and the effects of contact time were considered. Optimum adsorption pH values of chromium(VI), cadmium(II) and copper(II) were 2.0, 8.0 and 3.0 respectively. Experimental results also showed the influence of initial metal concentration on the metal uptake for dried biomass. Both the Freundlich and Langmuir adsorption models were suitable for describing the short-term biosorption of chromium(VI), cadmium(II) and copper(II) by O. anthropi."
1509611,Fritz et al. 2003,Rapid determination of ions by combined solid-phase extraction--diffuse reflectance spectroscopy,"We introduce colorimetric solid-phase extraction (C-SPE) for the rapid determination of selected ions. This new technique links the exhaustive concentration of an analyte by SPE onto a membrane disk surface for quantitative measurement with a hand-held diffuse reflectance spectrometer. The concentration/measurement procedure is complete in approximately 1 min and can be performed almost anywhere. This method has been used to monitor iodine and iodide in spacecraft water in the 0.1-5.0 ppm range and silver(I) in the range of 5.0-1000 microg/l. Applications to the trace analysis of copper(II), nickel(II), iron(III) and chromium(VI) are described. Studies on the mechanism of extraction showed that impregnation of the disk with a surfactant as well as a complexing reagent results in uptake of additional water, which markedly improves the extraction efficiency.","Rapid determination of ions by combined solid-phase extraction--diffuse reflectance spectroscopy Abs: We introduce colorimetric solid-phase extraction (C-SPE) for the rapid determination of selected ions. This new technique links the exhaustive concentration of an analyte by SPE onto a membrane disk surface for quantitative measurement with a hand-held diffuse reflectance spectrometer. The concentration/measurement procedure is complete in approximately 1 min and can be performed almost anywhere. This method has been used to monitor iodine and iodide in spacecraft water in the 0.1-5.0 ppm range and silver(I) in the range of 5.0-1000 microg/l. Applications to the trace analysis of copper(II), nickel(II), iron(III) and chromium(VI) are described. Studies on the mechanism of extraction showed that impregnation of the disk with a surfactant as well as a complexing reagent results in uptake of additional water, which markedly improves the extraction efficiency."
1509610,Filik et al. 2003,Speciation analysis of chromium by separation on a 5-palmitoyl oxine-functionalized XAD-2 resin and spectrophotometric determination with diphenylcarbazide,"The method developed in this work for the separation and preconcentration of Cr(III) is based on its retention by an Amberlite XAD-2 copolymer resin functionalized with 5-palmitoyl-8-hydroxyquinoline (oxine), abbreviated XAD-POx, with the ligand covalently bound to the copolymer. Cr(III) sorption was quantitative within the pH range 4.5-7.0 and Cr(VI) was not retained. The Cr(III) held by the resin column was eluted with a hot solution of H(2)O(2) in pH&gt;or=9.0 aqueous NH(3)-NH(4)Cl buffer, and Cr oxidized to CrO(4)(2-) was rejected by the chelating cation-exchanger column. Any Cr(VI) originally present with Cr(III) could be reduced with an acidic solution of H(2)O(2), and retained by the column yielding total Cr results, Cr(VI) being determined from the difference. The resin showed a maximal preconcentration factor of 60 for Cr(III), the LOD and LOQ being 9.3 and 30.1 nmol L(-1), respectively. The developed preconcentration-speciation analysis was finished with a diphenylcarbazide (DPC) spectrophotometric procedure suitable for conventional laboratories. The resin showed excellent salt tolerance, enabling Cr analysis in seawater, and was stable over extended use. All the interferents of this procedure that normally occur in an electroplating effluent, a blended coal CRM, and a standard steel sample could be removed by the recommended procedure, by use of partial and total selectivity at the adsorption and desorption stages, respectively, enabling preconcentration and colorimetric determination of chromium in various complex matrices.","Speciation analysis of chromium by separation on a 5-palmitoyl oxine-functionalized XAD-2 resin and spectrophotometric determination with diphenylcarbazide Abs: The method developed in this work for the separation and preconcentration of Cr(III) is based on its retention by an Amberlite XAD-2 copolymer resin functionalized with 5-palmitoyl-8-hydroxyquinoline (oxine), abbreviated XAD-POx, with the ligand covalently bound to the copolymer. Cr(III) sorption was quantitative within the pH range 4.5-7.0 and Cr(VI) was not retained. The Cr(III) held by the resin column was eluted with a hot solution of H(2)O(2) in pH&gt;or=9.0 aqueous NH(3)-NH(4)Cl buffer, and Cr oxidized to CrO(4)(2-) was rejected by the chelating cation-exchanger column. Any Cr(VI) originally present with Cr(III) could be reduced with an acidic solution of H(2)O(2), and retained by the column yielding total Cr results, Cr(VI) being determined from the difference. The resin showed a maximal preconcentration factor of 60 for Cr(III), the LOD and LOQ being 9.3 and 30.1 nmol L(-1), respectively. The developed preconcentration-speciation analysis was finished with a diphenylcarbazide (DPC) spectrophotometric procedure suitable for conventional laboratories. The resin showed excellent salt tolerance, enabling Cr analysis in seawater, and was stable over extended use. All the interferents of this procedure that normally occur in an electroplating effluent, a blended coal CRM, and a standard steel sample could be removed by the recommended procedure, by use of partial and total selectivity at the adsorption and desorption stages, respectively, enabling preconcentration and colorimetric determination of chromium in various complex matrices."
1509609,Xu et al. 2003,Chromium(VI) oxide catalyzed oxidation of sulfides to sulfones with periodic acid,A highly efficient and selective oxidation of sulfides to sulfones with periodic acid catalyzed by CrO(3) is described. A variety of electron-rich and electron-deficient sulfides were oxidized to sulfones with 2 mol % CrO(3) in acetonitrile at room temperature in excellent yields. Sulfides with other readily oxidized functional groups were selectively oxidized to sulfones in high yields with 10 mol % CrO(3) in ethyl acetate/acetonitrile at -35 degrees C.,Chromium(VI) oxide catalyzed oxidation of sulfides to sulfones with periodic acid Abs: A highly efficient and selective oxidation of sulfides to sulfones with periodic acid catalyzed by CrO(3) is described. A variety of electron-rich and electron-deficient sulfides were oxidized to sulfones with 2 mol % CrO(3) in acetonitrile at room temperature in excellent yields. Sulfides with other readily oxidized functional groups were selectively oxidized to sulfones in high yields with 10 mol % CrO(3) in ethyl acetate/acetonitrile at -35 degrees C.
1509608,Noroozifar and  Khorasani-Motlagh 2003,Specific extraction of chromium as tetrabutylammonium-chromate and spectrophotometric determination by diphenylcarbazide: speciation of chromium in effluent streams,"A very specific, selective, simple, and inexpensive procedure was developed for the speciation of CrVI and CrIII. This method is based on the quantitative extraction of chromate and CrIII (previously oxidized to CrVI) as a tetrabutylammonium-chromate ion-pair in methyl isobutyl ketone (MIBK), and then back extraction and preconcentration with an acidic diphenylcarbazide (DPC) solution. Back extraction was applied to achieve further preconcentration by a final factor of 20. The CrVI-DPC complex was determined in back-extract by a spectrophotometer at 548 nm. Under these extraction conditions, most of the probable concomitant cations and anions remained in the first inorganic phase. The calibration curve was linear up to 0.14 microg L(-1) of CrVI with a detection limit of 2.22 ng L(-1). The developed procedure was found to be suitable for the determination of the CrVI and CrIII species in various natural water samples with a relative standard deviation of better than 1.6%. The method was successfully applied to the speciation of chromium in spiked natural water samples, and also samples of effluent from a leather treatment plant.","Specific extraction of chromium as tetrabutylammonium-chromate and spectrophotometric determination by diphenylcarbazide: speciation of chromium in effluent streams Abs: A very specific, selective, simple, and inexpensive procedure was developed for the speciation of CrVI and CrIII. This method is based on the quantitative extraction of chromate and CrIII (previously oxidized to CrVI) as a tetrabutylammonium-chromate ion-pair in methyl isobutyl ketone (MIBK), and then back extraction and preconcentration with an acidic diphenylcarbazide (DPC) solution. Back extraction was applied to achieve further preconcentration by a final factor of 20. The CrVI-DPC complex was determined in back-extract by a spectrophotometer at 548 nm. Under these extraction conditions, most of the probable concomitant cations and anions remained in the first inorganic phase. The calibration curve was linear up to 0.14 microg L(-1) of CrVI with a detection limit of 2.22 ng L(-1). The developed procedure was found to be suitable for the determination of the CrVI and CrIII species in various natural water samples with a relative standard deviation of better than 1.6%. The method was successfully applied to the speciation of chromium in spiked natural water samples, and also samples of effluent from a leather treatment plant."
1509607,Locatelli 2003,Analytical procedure for the simultaneous voltammetric determination of toxic metals in dialysis fluids,"A new analytical voltammetric procedure for the simultaneous determination of copper(II), lead(II), cadmium(II), zinc(II), chromium(VI), and manganese(II) in two kinds of dialysis fluid (peritoneal and haemodialysis fluids) is described. The voltammetric measurements were performed using, as working electrode, a stationary mercury electrode, and a platinum electrode and a Agmid R:AgClmid R:KCl ((sat.)) electrode as auxiliary and reference electrodes, respectively, employing 0.1 mol L(-1) dibasic ammonium citrate solution pH 6.9 as supporting electrolyte. For all the elements, the accuracy, expressed as relative recovery R%, was very satisfactory being in the range 94-105%, the precision, expressed as relative standard deviation s(r)%, was lower than 6%, while the limits of detection were of the order of a few units of microg L(-1). The analytical voltammetric procedure has been validated by comparison with spectroscopic (graphite furnace atomic absorption spectroscopy, GFAAS) measurements.","Analytical procedure for the simultaneous voltammetric determination of toxic metals in dialysis fluids Abs: A new analytical voltammetric procedure for the simultaneous determination of copper(II), lead(II), cadmium(II), zinc(II), chromium(VI), and manganese(II) in two kinds of dialysis fluid (peritoneal and haemodialysis fluids) is described. The voltammetric measurements were performed using, as working electrode, a stationary mercury electrode, and a platinum electrode and a Agmid R:AgClmid R:KCl ((sat.)) electrode as auxiliary and reference electrodes, respectively, employing 0.1 mol L(-1) dibasic ammonium citrate solution pH 6.9 as supporting electrolyte. For all the elements, the accuracy, expressed as relative recovery R%, was very satisfactory being in the range 94-105%, the precision, expressed as relative standard deviation s(r)%, was lower than 6%, while the limits of detection were of the order of a few units of microg L(-1). The analytical voltammetric procedure has been validated by comparison with spectroscopic (graphite furnace atomic absorption spectroscopy, GFAAS) measurements."
1509606,Hillier et al. 2003,Role of quantitative mineralogical analysis in the investigation of sites contaminated by chromite ore processing residue,"A range of techniques, normally associated with mineralogical studies of soils and sediments, has been used to characterise the solid materials found on sites contaminated with chromite ore processing residue (COPR). The results show that a wide range of minerals are present, many of which are found extensively in high-temperature synthetic systems such as cements and clinkers and their low temperature hydration products. Thus, the minerals in COPR can be divided into three main categories: unreacted feedstock ore (chromite); high temperature phases produced during chromium extraction (brownmillerite, periclase and larnite); and finally, minerals formed under ambient weathering conditions on the disposal sites (brucite, calcite, aragonite, ettringite, hydrocalumite, hydrogarnet). Apart from chromite, chromium occurs in brownmillerite, ettringite, hydrocalumite and hydrogarnet. Detailed study of the chemistry and stoichiometry of chromium-bearing phases in conjunction with phase abundance provides a quantitative description of the solid state speciation of Cr(III) and Cr(VI) in and amongst these minerals and in the COPR as a whole. Of the total chromium present in the samples most, approximately 60-70% is present as Cr(III) in chromite, whilst brownmillerite also represents a significant reservoir of Cr(III) which is approximately 15% of the total. The remaining chromium, between 20 and 25%, is present as Cr(VI) and resides mainly in hydrogarnet, and to a slightly lesser extent in hydrocalumite. In the latter, it is present principally in an exchangeable anionic form. Chromium (VI) is also present in ettringite, but quantitatively ettringite is a much less important reservoir of Cr(VI), accounting for approximately 3% of total chromium in one sample, but less than 1% in the other two. This description provides insight into the processes likely to control the retention and release of Cr(VI) from COPR-contaminated sites. Such information is of particular value in chemical modelling of the system, in risk assessment and in the development of methods of informed remediation.","Role of quantitative mineralogical analysis in the investigation of sites contaminated by chromite ore processing residue Abs: A range of techniques, normally associated with mineralogical studies of soils and sediments, has been used to characterise the solid materials found on sites contaminated with chromite ore processing residue (COPR). The results show that a wide range of minerals are present, many of which are found extensively in high-temperature synthetic systems such as cements and clinkers and their low temperature hydration products. Thus, the minerals in COPR can be divided into three main categories: unreacted feedstock ore (chromite); high temperature phases produced during chromium extraction (brownmillerite, periclase and larnite); and finally, minerals formed under ambient weathering conditions on the disposal sites (brucite, calcite, aragonite, ettringite, hydrocalumite, hydrogarnet). Apart from chromite, chromium occurs in brownmillerite, ettringite, hydrocalumite and hydrogarnet. Detailed study of the chemistry and stoichiometry of chromium-bearing phases in conjunction with phase abundance provides a quantitative description of the solid state speciation of Cr(III) and Cr(VI) in and amongst these minerals and in the COPR as a whole. Of the total chromium present in the samples most, approximately 60-70% is present as Cr(III) in chromite, whilst brownmillerite also represents a significant reservoir of Cr(III) which is approximately 15% of the total. The remaining chromium, between 20 and 25%, is present as Cr(VI) and resides mainly in hydrogarnet, and to a slightly lesser extent in hydrocalumite. In the latter, it is present principally in an exchangeable anionic form. Chromium (VI) is also present in ettringite, but quantitatively ettringite is a much less important reservoir of Cr(VI), accounting for approximately 3% of total chromium in one sample, but less than 1% in the other two. This description provides insight into the processes likely to control the retention and release of Cr(VI) from COPR-contaminated sites. Such information is of particular value in chemical modelling of the system, in risk assessment and in the development of methods of informed remediation."
1509605,Kubán et al. 2003,Speciation of chromium (III) and chromium (VI) by capillary electrophoresis with contactless conductometric detection and dual opposite end injection,"A sensitive, rapid and inexpensive capillary electrophoretic method for the determination of Cr(III) and Cr(VI) species is presented. The method is based on the dual opposite end injection principle and contactless conductometric detection. The sample containing cationic and anionic species is injected into the opposite ends of the separation capillary and after the high voltage is applied, the analytes migrate towards the capillary center, where the cell of a contactless conductivity detector is placed. The method does not require any sample pretreatment, except dilution with deionized water. The separation of Cr(III), Cr(VI) and other common inorganic anions and cations is achieved in less than 4 min. The parameters of the separation electrolyte solution, such as pH and concentration of L-histidine, were optimized. Best results were achieved with electrolyte solution consisting of 4.5 mM L-histidine, adjusted to pH 3.40 with acetic acid. The detection limits achieved for Cr(III) and Cr(VI) were 10 and 39 microg.L(-1), respectively. The repeatability of migration times and peak areas was better than 0.3% and 2.8%, respectively. The developed method was applied to the analyses of rinse water samples from the galvanic industry. The results for the determination of Cr(III) and Cr(VI) were in good agreement with the results obtained by certified differential spectrophotometric method using diphenylcarbazide (CN 83 0520-40) and with the results for the total chromium concentrations determined by electrothermal atomic absorbance spectrometry (ET-AAS) and inductively coupled plasma-mass spectrometry (ICP-MS).","Speciation of chromium (III) and chromium (VI) by capillary electrophoresis with contactless conductometric detection and dual opposite end injection Abs: A sensitive, rapid and inexpensive capillary electrophoretic method for the determination of Cr(III) and Cr(VI) species is presented. The method is based on the dual opposite end injection principle and contactless conductometric detection. The sample containing cationic and anionic species is injected into the opposite ends of the separation capillary and after the high voltage is applied, the analytes migrate towards the capillary center, where the cell of a contactless conductivity detector is placed. The method does not require any sample pretreatment, except dilution with deionized water. The separation of Cr(III), Cr(VI) and other common inorganic anions and cations is achieved in less than 4 min. The parameters of the separation electrolyte solution, such as pH and concentration of L-histidine, were optimized. Best results were achieved with electrolyte solution consisting of 4.5 mM L-histidine, adjusted to pH 3.40 with acetic acid. The detection limits achieved for Cr(III) and Cr(VI) were 10 and 39 microg.L(-1), respectively. The repeatability of migration times and peak areas was better than 0.3% and 2.8%, respectively. The developed method was applied to the analyses of rinse water samples from the galvanic industry. The results for the determination of Cr(III) and Cr(VI) were in good agreement with the results obtained by certified differential spectrophotometric method using diphenylcarbazide (CN 83 0520-40) and with the results for the total chromium concentrations determined by electrothermal atomic absorbance spectrometry (ET-AAS) and inductively coupled plasma-mass spectrometry (ICP-MS)."
1509604,Benyehuda et al. 2003,Metal resistance among aerobic chemoheterotrophic bacteria from the deep terrestrial subsurface,"The metal resistance of 350 subsurface bacterial strains from two U.S. Department of Energy facilities, the Savannah River Site (SRS), South Carolina, and the Hanford site, Washington, was determined to assess the effect of metal toxicity on microorganisms in the deep terrestrial subsurface. Resistance was measured by growth inhibition around discs containing optimized amounts of Hg(II), Pb(II), and Cr(VI). A broad range of resistance levels was observed, with some strains of Arthrobacter spp. demonstrating exceptional tolerance. A higher level of resistance to Hg(II) and Pb(II) (P &lt; 0.05) and a higher occurrence of multiple resistances suggested that metals more effectively influenced microbial evolution in subsurface sediments of the SRS than in those of the Hanford site. Common resistance to heavy metals suggests that toxic metals are unlikely to inhibit bioremediation in deep subsurface environments that are contaminated with mixed wastes.","Metal resistance among aerobic chemoheterotrophic bacteria from the deep terrestrial subsurface Abs: The metal resistance of 350 subsurface bacterial strains from two U.S. Department of Energy facilities, the Savannah River Site (SRS), South Carolina, and the Hanford site, Washington, was determined to assess the effect of metal toxicity on microorganisms in the deep terrestrial subsurface. Resistance was measured by growth inhibition around discs containing optimized amounts of Hg(II), Pb(II), and Cr(VI). A broad range of resistance levels was observed, with some strains of Arthrobacter spp. demonstrating exceptional tolerance. A higher level of resistance to Hg(II) and Pb(II) (P &lt; 0.05) and a higher occurrence of multiple resistances suggested that metals more effectively influenced microbial evolution in subsurface sediments of the SRS than in those of the Hanford site. Common resistance to heavy metals suggests that toxic metals are unlikely to inhibit bioremediation in deep subsurface environments that are contaminated with mixed wastes."
1509603,Zahn et al. 2003,EC STM investigations of corrosion due to chloride solutions on thin CrN coatings,"The focus of the investigations presented is to evaluate local alterations caused by chloride ions affecting thin, magnetron-sputtered CrN layers. Scanning-probe microscopy and analysis techniques are used for this estimation. Thin CrN layers were deposited by reactive magnetron sputtering. They were investigated in electrochemical scanning tunnelling microscopy (EC STM) by cyclic voltammetry in 1 mol L(-1) NaCl. Simultaneously, the surface topography changes were recorded with STM. Above 100 mV the anodic oxidation leads to formation of chromium(III) hydroxide and at sample potentials above 350 mV oxidation of Cr(OH)(2) and Cr(OH)(3) towards chromium(VI) as a soluble chromate starts. Transpassive dissolution of the coating takes place above 900 mV. Yellow colour of the electrolyte is a visible sign for the formation of chromium(VI). Changes of the surface topography indicate the formation of surface layers at anodic potentials. At cathodic potentials increase in current is measured due to the reduction of chromium(III) hydroxide to divalent chromium and metallic chromium. Roughness of surface topography increases.Follow-up explorations with scanning electron microscopy (SEM), energy-dispersive X-ray spectroscopy (EDX), atomic-force microscopy (AFM), scanning tunnelling microscopy/scanning tunnelling spectroscopy (STM/STS) and X-ray photoelectron spectroscopy (XPS) not only evidence the formation of various chromium oxides, but also indicate the existence of chromium hydroxide.","EC STM investigations of corrosion due to chloride solutions on thin CrN coatings Abs: The focus of the investigations presented is to evaluate local alterations caused by chloride ions affecting thin, magnetron-sputtered CrN layers. Scanning-probe microscopy and analysis techniques are used for this estimation. Thin CrN layers were deposited by reactive magnetron sputtering. They were investigated in electrochemical scanning tunnelling microscopy (EC STM) by cyclic voltammetry in 1 mol L(-1) NaCl. Simultaneously, the surface topography changes were recorded with STM. Above 100 mV the anodic oxidation leads to formation of chromium(III) hydroxide and at sample potentials above 350 mV oxidation of Cr(OH)(2) and Cr(OH)(3) towards chromium(VI) as a soluble chromate starts. Transpassive dissolution of the coating takes place above 900 mV. Yellow colour of the electrolyte is a visible sign for the formation of chromium(VI). Changes of the surface topography indicate the formation of surface layers at anodic potentials. At cathodic potentials increase in current is measured due to the reduction of chromium(III) hydroxide to divalent chromium and metallic chromium. Roughness of surface topography increases.Follow-up explorations with scanning electron microscopy (SEM), energy-dispersive X-ray spectroscopy (EDX), atomic-force microscopy (AFM), scanning tunnelling microscopy/scanning tunnelling spectroscopy (STM/STS) and X-ray photoelectron spectroscopy (XPS) not only evidence the formation of various chromium oxides, but also indicate the existence of chromium hydroxide."
1509602,Farkas et al. 2003,Effects of hexavalent chromium on the plasma membranes of sensitive and tolerant mutants of Schizosaccharomyces pombe. An EPR study,"The interactions of chromium(VI) with the plasma membranes of chromium-sensitive (chr-51S) and chromium-tolerant (chr1-66T) mutants and their parental strain (6chr(+)) of a Schizosaccharomyces pombe strain were studied by electron paramagnetic resonance (EPR) spectroscopy. 5-doxylstearic acid (5-SASL) and 3-doxylbutyric acid (HO-185) spin probes were used to label the membranes. The order parameter S from the EPR spectra was calculated at different temperatures (0-25 degrees C) in order to characterize the internal dynamics of the membranes. In control experiments, both mutants exhibited differences in structural transitions in the both 5-SASL- and the HO-185-labeled membranes in comparison with their parental strain, suggesting differences in the membrane composition and/or rotational dynamics of these mutants. Addition of K(2)Cr(2)O(7) (225 microM) induced small decreases in the phase transition temperatures of the 5-SASL-labeled membranes of the parental and chromium-sensitive strains. More pronounced effects of the chromium compound on the HO-185-labeled membranes were detected as evidence that the membrane perturbations are mostly localized in the environment of the lipid-water interface.","Effects of hexavalent chromium on the plasma membranes of sensitive and tolerant mutants of Schizosaccharomyces pombe. An EPR study Abs: The interactions of chromium(VI) with the plasma membranes of chromium-sensitive (chr-51S) and chromium-tolerant (chr1-66T) mutants and their parental strain (6chr(+)) of a Schizosaccharomyces pombe strain were studied by electron paramagnetic resonance (EPR) spectroscopy. 5-doxylstearic acid (5-SASL) and 3-doxylbutyric acid (HO-185) spin probes were used to label the membranes. The order parameter S from the EPR spectra was calculated at different temperatures (0-25 degrees C) in order to characterize the internal dynamics of the membranes. In control experiments, both mutants exhibited differences in structural transitions in the both 5-SASL- and the HO-185-labeled membranes in comparison with their parental strain, suggesting differences in the membrane composition and/or rotational dynamics of these mutants. Addition of K(2)Cr(2)O(7) (225 microM) induced small decreases in the phase transition temperatures of the 5-SASL-labeled membranes of the parental and chromium-sensitive strains. More pronounced effects of the chromium compound on the HO-185-labeled membranes were detected as evidence that the membrane perturbations are mostly localized in the environment of the lipid-water interface."
1509601,Ksheminska et al. 2003,Bioremediation of chromium by the yeast Pichia guilliermondii: toxicity and accumulation of Cr (III) and Cr (VI) and the influence of riboflavin on Cr tolerance,"A comparative study has been made on the sensitivity of the yeast Pichia guilliermondii to Cr (III) and Cr (VI) as well as on the Cr uptake potential at growth-inhibitory concentrations of chromium. The strains used in the study were either isolated from natural sources or obtained from a laboratory strain collection. The results show that most of the natural strains were more tolerant to chromium and were able to grow in the presence of 5 mM Cr (III) or 0.5 mM Cr (VI), that is at concentrations which substantially inhibited the growth of laboratory strains. The cellular Cr content after treatment was similar for both strain types and ranged from 1.2-4.0 mg/g d.w. and 0.4-0.9 mg/g d.w., for Cr (III) and Cr (VI) forms, respectively, however, in one case of a natural strain it reached the value of 10 mg Cr (III)/g dry mass. Natural-source strains were grouped into four groups based on the yeasts' differential response to Cr (III) and Cr (VI). Hexavalent Cr-resistant mutants of a P. giuilliermondii laboratory strain, which revealed markedly changed capabilities of chromium accumulation, were obtained by means of UV-induced mutagenesis. Cr (VI) treatment triggered oversynthesis of riboflavin and the addition of exogenous riboflavin increased P. guilliermondii resistance to both Cr (III) and Cr (VI). Electrophoretic protein profiles revealed the induction and/or suppression of several proteins in response to toxic Cr (VI) levels.","Bioremediation of chromium by the yeast Pichia guilliermondii: toxicity and accumulation of Cr (III) and Cr (VI) and the influence of riboflavin on Cr tolerance Abs: A comparative study has been made on the sensitivity of the yeast Pichia guilliermondii to Cr (III) and Cr (VI) as well as on the Cr uptake potential at growth-inhibitory concentrations of chromium. The strains used in the study were either isolated from natural sources or obtained from a laboratory strain collection. The results show that most of the natural strains were more tolerant to chromium and were able to grow in the presence of 5 mM Cr (III) or 0.5 mM Cr (VI), that is at concentrations which substantially inhibited the growth of laboratory strains. The cellular Cr content after treatment was similar for both strain types and ranged from 1.2-4.0 mg/g d.w. and 0.4-0.9 mg/g d.w., for Cr (III) and Cr (VI) forms, respectively, however, in one case of a natural strain it reached the value of 10 mg Cr (III)/g dry mass. Natural-source strains were grouped into four groups based on the yeasts' differential response to Cr (III) and Cr (VI). Hexavalent Cr-resistant mutants of a P. giuilliermondii laboratory strain, which revealed markedly changed capabilities of chromium accumulation, were obtained by means of UV-induced mutagenesis. Cr (VI) treatment triggered oversynthesis of riboflavin and the addition of exogenous riboflavin increased P. guilliermondii resistance to both Cr (III) and Cr (VI). Electrophoretic protein profiles revealed the induction and/or suppression of several proteins in response to toxic Cr (VI) levels."
1509600,Daulton et al. 2001,In Situ Environmental Cell-Transmission Electron Microscopy Study of Microbial Reduction of Chromium(VI) Using Electron Energy Loss Spectroscopy,"Reduction of Cr(VI) by the bacterium, Shewanella oneidensis (previously classified Shewanella putrefaciens strain MR-1), was studied by absorption spectrophotometry and in situ, environmental cell-transmission electron microscopy (EC-TEM) coupled with electron energy loss spectroscopy (EELS). Bacteria from rinsed cultures were placed directly in the environmental cell of the transmission electron microscope and examined under 100 Torr pressure. Bright field EC-TEM images show two distinct populations of S. oneidensis in incubated cultures containing Cr(VI)O2- 4: those that exhibit low image contrast and heavily precipitate-encrusted cells exhibiting high image contrast. Several EELS techniques were applied to determine the oxidation state of Cr associated with encrusted cells. The encrusted cells are shown to contain a reduced form of Cr in oxidation state +3 or lower. These results demonstrate the capability to determine the chemistry and valence state of reduction products associated with unfixed, hydrated bacteria in an environmental cell transmission electron microscope.","In Situ Environmental Cell-Transmission Electron Microscopy Study of Microbial Reduction of Chromium(VI) Using Electron Energy Loss Spectroscopy Abs: Reduction of Cr(VI) by the bacterium, Shewanella oneidensis (previously classified Shewanella putrefaciens strain MR-1), was studied by absorption spectrophotometry and in situ, environmental cell-transmission electron microscopy (EC-TEM) coupled with electron energy loss spectroscopy (EELS). Bacteria from rinsed cultures were placed directly in the environmental cell of the transmission electron microscope and examined under 100 Torr pressure. Bright field EC-TEM images show two distinct populations of S. oneidensis in incubated cultures containing Cr(VI)O2- 4: those that exhibit low image contrast and heavily precipitate-encrusted cells exhibiting high image contrast. Several EELS techniques were applied to determine the oxidation state of Cr associated with encrusted cells. The encrusted cells are shown to contain a reduced form of Cr in oxidation state +3 or lower. These results demonstrate the capability to determine the chemistry and valence state of reduction products associated with unfixed, hydrated bacteria in an environmental cell transmission electron microscope."
1509599,Srinath et al. 2001,Isolation of hexavalent chromium-reducing Cr-tolerant facultative anaerobes from tannery effluent,"Several facultative anaerobes tolerant to high levels of chromate (&gt;400 mg/ml) were isolated from tannery effluents. These isolates displayed varying degrees of Cr(VI) reduction under aerobic and anaerobic conditions at room temperature (24+/-2 degrees C). Interestingly, eight isolates were efficient in reducing 70% Cr(VI) anaerobically. This includes 5 isolates of genus Aerococcus, two isolates of Micrococcus and single isolate of genus Aeromonas. These isolates were subjected to further characterization for possible use in Cr(VI) detoxification of industrial wastes. This is the first report of Aerococcus sp. capable of Cr(VI) reduction &gt;70% anaerobically. These bacteria were further checked for tolerance to a variety of other heavy metals. Our study indicates the possible use of these bacteria in environmental clean up.","Isolation of hexavalent chromium-reducing Cr-tolerant facultative anaerobes from tannery effluent Abs: Several facultative anaerobes tolerant to high levels of chromate (&gt;400 mg/ml) were isolated from tannery effluents. These isolates displayed varying degrees of Cr(VI) reduction under aerobic and anaerobic conditions at room temperature (24+/-2 degrees C). Interestingly, eight isolates were efficient in reducing 70% Cr(VI) anaerobically. This includes 5 isolates of genus Aerococcus, two isolates of Micrococcus and single isolate of genus Aeromonas. These isolates were subjected to further characterization for possible use in Cr(VI) detoxification of industrial wastes. This is the first report of Aerococcus sp. capable of Cr(VI) reduction &gt;70% anaerobically. These bacteria were further checked for tolerance to a variety of other heavy metals. Our study indicates the possible use of these bacteria in environmental clean up."
1509598,Ko and  Baek 2002,The oxidation of fullerene [C70] with various oxidants by ultrasonication,"The reaction of C70 by ultrasonication with various oxidants such as 3-chloroperoxy benzoic acid (Fluka 99%), 4-methyl morpholine N-oxide (Aldrich 97%), chromium (VI) oxide (Aldrich 99.9%), and oxone monopersulfate compound, at room temperature causes the oxidation of fullerene [C70(O)n] (n = 1-2 or n = 1). The FAB-MS, UV-visible, FT-IR spectra, and HPLC analysis confirmed that products of fullerene oxidation are [C70(O)n] (n = 1-2 or n = 1).","The oxidation of fullerene [C70] with various oxidants by ultrasonication Abs: The reaction of C70 by ultrasonication with various oxidants such as 3-chloroperoxy benzoic acid (Fluka 99%), 4-methyl morpholine N-oxide (Aldrich 97%), chromium (VI) oxide (Aldrich 99.9%), and oxone monopersulfate compound, at room temperature causes the oxidation of fullerene [C70(O)n] (n = 1-2 or n = 1). The FAB-MS, UV-visible, FT-IR spectra, and HPLC analysis confirmed that products of fullerene oxidation are [C70(O)n] (n = 1-2 or n = 1)."
1509597,Roh et al. 2002,"Isolation and characterization of metal-reducing thermoanaerobacter strains from deep subsurface environments of the Piceance Basin, Colorado","Five bacterial strains were isolated from anaerobic enrichment cultures that had originated from inoculations with samples collected from the deep subsurface environments of the millions-of-years-old, geologically and hydrologically isolated Piceance Basin in Colorado. Small-subunit rRNA gene-based analyses indicated that all of these bacteria were closely related to Thermoanaerobacter ethanolicus, with similarities of 99.4 to 99.5%. Three isolates (X513, X514, and X561) from the five bacterial strains were used to examine physiological characteristics. These thermophilic bacteria were able to use acetate, glucose, hydrogen, lactate, pyruvate, succinate, and xylose as electron donors while reducing Fe(III), cobalt(III), chromium(VI), manganese(IV), and uranium(VI) at 60 degrees C. One of the isolates (X514) was also able to utilize hydrogen as an electron donor for Fe(III) reduction. These bacteria exhibited diverse mineral precipitation capabilities, including the formation of magnetite (Fe(3)O(4)), siderite (FeCO(3)), rhodochrosite (MnCO(3)), and uraninite (UO(2)). The gas composition of the incubation headspace and the ionic composition of the incubation medium exerted profound influences on the types of minerals formed. The susceptibility of the thermophilic Fe(III)-reducing cultures to metabolic inhibitors specific for ferric reductase, hydrogenase, and electron transport indicated that iron reduction by these bacteria is an enzymatic process.","Isolation and characterization of metal-reducing thermoanaerobacter strains from deep subsurface environments of the Piceance Basin, Colorado Abs: Five bacterial strains were isolated from anaerobic enrichment cultures that had originated from inoculations with samples collected from the deep subsurface environments of the millions-of-years-old, geologically and hydrologically isolated Piceance Basin in Colorado. Small-subunit rRNA gene-based analyses indicated that all of these bacteria were closely related to Thermoanaerobacter ethanolicus, with similarities of 99.4 to 99.5%. Three isolates (X513, X514, and X561) from the five bacterial strains were used to examine physiological characteristics. These thermophilic bacteria were able to use acetate, glucose, hydrogen, lactate, pyruvate, succinate, and xylose as electron donors while reducing Fe(III), cobalt(III), chromium(VI), manganese(IV), and uranium(VI) at 60 degrees C. One of the isolates (X514) was also able to utilize hydrogen as an electron donor for Fe(III) reduction. These bacteria exhibited diverse mineral precipitation capabilities, including the formation of magnetite (Fe(3)O(4)), siderite (FeCO(3)), rhodochrosite (MnCO(3)), and uraninite (UO(2)). The gas composition of the incubation headspace and the ionic composition of the incubation medium exerted profound influences on the types of minerals formed. The susceptibility of the thermophilic Fe(III)-reducing cultures to metabolic inhibitors specific for ferric reductase, hydrogenase, and electron transport indicated that iron reduction by these bacteria is an enzymatic process."
1509596,Lee and  Fuchs 2002,Chemospecific chromium[VI] catalyzed oxidation of C-H bonds at -40 degrees C1,H5IO6 in the presence of catalytic chromoyl diacetate is a powerful method for oxidation of C-H bonds. Tertiary and oxygen activated C-H bonds are oxidized to tertiary alcohols or ketones at temperatures as low as -40 degrees C. The putative reagent is neutral dioxoperoxy chromium[VI] which undergoes C-H oxidation with retention of stereochemistry. This reagent appears to be the first reagent capable of oxidation of a C-H bond in the presence of an olefin without concomitant epoxidation.,Chemospecific chromium[VI] catalyzed oxidation of C-H bonds at -40 degrees C1 Abs: H5IO6 in the presence of catalytic chromoyl diacetate is a powerful method for oxidation of C-H bonds. Tertiary and oxygen activated C-H bonds are oxidized to tertiary alcohols or ketones at temperatures as low as -40 degrees C. The putative reagent is neutral dioxoperoxy chromium[VI] which undergoes C-H oxidation with retention of stereochemistry. This reagent appears to be the first reagent capable of oxidation of a C-H bond in the presence of an olefin without concomitant epoxidation.
1509595,Bayat 2002,Comparative study of adsorption properties of Turkish fly ashes. II. The case of chromium (VI) and cadmium (II),"The purpose of the study described in this paper was to compare the removal of Cr(VI) and Cd(II) from an aqueous solution using two different Turkish fly ashes; Afsin-Elbistan and Seyitomer as adsorbents. The influence of four parameters (contact time, solution pH, initial metal concentration in solution and ash quality) on the removal at 20+/-2 degrees C was studied. Fly ashes were found to have a higher adsorption capacity for the adsorption of Cd(II) as compared to Cr(VI) and both Cr(VI) and Cd(II) required an equilibrium time of 2h. The adsorption of Cr(VI) was higher at pH 4.0 for Afsin-Elbistan fly ash (25.46%) and pH 3.0 for Seyitomer fly ash (30.91%) while Cd(II) was adsorbed to a greater extent (98.43% for Afsin-Elbistan fly ash and 65.24% for Seyitomer fly ash) at pH 7.0. The adsorption of Cd(II) increased with an increase in the concentrations of these metals in solution while Cr(VI) adsorption decreased by both fly ashes. The lime (crystalline CaO) content in fly ash seemed to be a significant factor in influencing Cr(VI) and Cd(II) ions removal. The linear forms of the Langmuir and Freundlich equations were utilised for experiments with metal concentrations of 55+/-2mg/l for Cr(VI) and 6+/-0.2mg/l for Cd(II) as functions of solution pH (3.0-8.0). The adsorption of Cr(VI) on both fly ashes was not described by both the Langmuir and Freundlich isotherms while Cd(II) adsorption on both fly ashes satisfied only the Langmuir isotherm model. The adsorption capacities of both fly ashes were nearly three times less than that of activated carbon for the removal of Cr(VI) while Afsin-Elbistan fly ash with high-calcium content was as effective as activated carbon for the removal of Cd(II). Therefore, there are possibilities for use the adsorption of Cd(II) ions onto fly ash with high-calcium content in practical applications in Turkey.","Comparative study of adsorption properties of Turkish fly ashes. II. The case of chromium (VI) and cadmium (II) Abs: The purpose of the study described in this paper was to compare the removal of Cr(VI) and Cd(II) from an aqueous solution using two different Turkish fly ashes; Afsin-Elbistan and Seyitomer as adsorbents. The influence of four parameters (contact time, solution pH, initial metal concentration in solution and ash quality) on the removal at 20+/-2 degrees C was studied. Fly ashes were found to have a higher adsorption capacity for the adsorption of Cd(II) as compared to Cr(VI) and both Cr(VI) and Cd(II) required an equilibrium time of 2h. The adsorption of Cr(VI) was higher at pH 4.0 for Afsin-Elbistan fly ash (25.46%) and pH 3.0 for Seyitomer fly ash (30.91%) while Cd(II) was adsorbed to a greater extent (98.43% for Afsin-Elbistan fly ash and 65.24% for Seyitomer fly ash) at pH 7.0. The adsorption of Cd(II) increased with an increase in the concentrations of these metals in solution while Cr(VI) adsorption decreased by both fly ashes. The lime (crystalline CaO) content in fly ash seemed to be a significant factor in influencing Cr(VI) and Cd(II) ions removal. The linear forms of the Langmuir and Freundlich equations were utilised for experiments with metal concentrations of 55+/-2mg/l for Cr(VI) and 6+/-0.2mg/l for Cd(II) as functions of solution pH (3.0-8.0). The adsorption of Cr(VI) on both fly ashes was not described by both the Langmuir and Freundlich isotherms while Cd(II) adsorption on both fly ashes satisfied only the Langmuir isotherm model. The adsorption capacities of both fly ashes were nearly three times less than that of activated carbon for the removal of Cr(VI) while Afsin-Elbistan fly ash with high-calcium content was as effective as activated carbon for the removal of Cd(II). Therefore, there are possibilities for use the adsorption of Cd(II) ions onto fly ash with high-calcium content in practical applications in Turkey."
1509594,Scindia et al. 2002,Selective preconcentration and determination of chromium(VI) using a flat sheet polymer inclusion sorbent: potential application for Cr(VI) determination in real samples,"A method for sorption preconcentration of Cr(VI) from aqueous samples was developed using a polymer inclusion sorbent (PIS). The PIS used in this method was prepared by physical inclusion of Aliquat-336 in the matrix formed by cellulose triacetate and 2-nitrophenyl octyl ether. This sorbent was found to be stable, cost-effective, efficient for preconcentration of Cr(VI) present in the aqueous samples, and amenable to direct quantitative analysis of Cr(VI) held in it by neutron activation analysis and spectrophotometry. The quantifying of Cr(VI) in PIS by spectrophotometry was carried out by developing color directly on the PIS after reacting it with 1,5-diphenylcarbazide. The distinct color developed on the PIS even at very low concentrations of Cr(VI) suggests its possible use for field determination of Cr(VI). The composition of PIS was optimized to obtain maximum uptake of Cr(VI) without sacrificing uniformity in terms of thickness and distribution of ion-exchange sites, stability, and time required for quantitative sorption of Cr(VI) from aqueous samples. The Cr(VI) species held in the PIS, mainly HCrO4- and CrO4(2-), were found to vary as a function of pH of the aqueous samples from which Cr(VI) was preconcentrated. A close agreement was found in the abundances of Cr(VI) species held in the PIS with those reported in the literature for aqueous solutions at different pH. The variation of Cr(VI) species as a function of pH was found to have a significant impact on the tolerance to anions on the uptake of Cr(VI) in the PIS. The high selectivity of PIS toward Cr(VI) from aqueous solution at pH = 2 was explained on the basis of hydration of anions. The uptake of Cr(VI) was found to be fairly constant (88 +/- 3%) up to nearly complete exchange of counterions present in the PIS. The method developed in the present work was successfully used for the preconcentration of Cr(VI) from tap water and seawater samples containing low levels of Cr(VI).","Selective preconcentration and determination of chromium(VI) using a flat sheet polymer inclusion sorbent: potential application for Cr(VI) determination in real samples Abs: A method for sorption preconcentration of Cr(VI) from aqueous samples was developed using a polymer inclusion sorbent (PIS). The PIS used in this method was prepared by physical inclusion of Aliquat-336 in the matrix formed by cellulose triacetate and 2-nitrophenyl octyl ether. This sorbent was found to be stable, cost-effective, efficient for preconcentration of Cr(VI) present in the aqueous samples, and amenable to direct quantitative analysis of Cr(VI) held in it by neutron activation analysis and spectrophotometry. The quantifying of Cr(VI) in PIS by spectrophotometry was carried out by developing color directly on the PIS after reacting it with 1,5-diphenylcarbazide. The distinct color developed on the PIS even at very low concentrations of Cr(VI) suggests its possible use for field determination of Cr(VI). The composition of PIS was optimized to obtain maximum uptake of Cr(VI) without sacrificing uniformity in terms of thickness and distribution of ion-exchange sites, stability, and time required for quantitative sorption of Cr(VI) from aqueous samples. The Cr(VI) species held in the PIS, mainly HCrO4- and CrO4(2-), were found to vary as a function of pH of the aqueous samples from which Cr(VI) was preconcentrated. A close agreement was found in the abundances of Cr(VI) species held in the PIS with those reported in the literature for aqueous solutions at different pH. The variation of Cr(VI) species as a function of pH was found to have a significant impact on the tolerance to anions on the uptake of Cr(VI) in the PIS. The high selectivity of PIS toward Cr(VI) from aqueous solution at pH = 2 was explained on the basis of hydration of anions. The uptake of Cr(VI) was found to be fairly constant (88 +/- 3%) up to nearly complete exchange of counterions present in the PIS. The method developed in the present work was successfully used for the preconcentration of Cr(VI) from tap water and seawater samples containing low levels of Cr(VI)."
1509593,Ernstberger et al. 2002,Determination of chromium speciation in natural systems using DGT,"The techniques of diffusive gradients (DGT) and equilibration (DET) in thin-films have been combined in a single probe that can determine Cr(III) and Cr(VI) simultaneously in solution. The assembly has a layer of polyacrylamide hydrogel overlying a separate layer of resin embedded in gel. Cr(III) species accumulate exclusively and quantitatively in the resin layer, while Cr(VI) species equilibrate with both hydrogel and resin layers. The species are separated by peeling the two layers apart. Chromium is then eluted from each of the two layers. Cr(III) and Cr(VI) were determined quantitatively in standard, mixed solutions by in situ separation with DGT and detection by GF-AAS. With this method, Cr(III) is typically preconcentrated by a factor of 10 over a 24 h deployment, and limits of detection of 8 ng/L Cr(III) and 0.3 micro g/L Cr(VI) were achieved. Due to the inbuilt preconcentration of Cr(III), the technique is particularly good at measuring low concentrations of Cr(III) in the presence of an excess of Cr(VI). Measurements were performed in three soils with various levels of chromium contamination. A concentration of 3 micro g/L of labile Cr(III) was measured reproducibly in the presence of 290 micro g/L of unreactive Cr species and 0.2 micro g/L of labile Cr(III) was measured in the presence of 24 micro g/L of unreactive Cr. The unique feature of the method is that the separation of Cr(III) from Cr(VI) occurs in situ. The Cr species are then stable in the resin and gel prior to analysis, eliminating the artefacts associated with sampling and storage, which are particularly prevalent for redox-sensitive elements. Therefore, it has great potential for assessing Cr(III) and Cr(VI) concentrations in situ in environments near redox boundaries where possible dynamic changes in Cr(III) and Cr(VI) concentrations are occurring.","Determination of chromium speciation in natural systems using DGT Abs: The techniques of diffusive gradients (DGT) and equilibration (DET) in thin-films have been combined in a single probe that can determine Cr(III) and Cr(VI) simultaneously in solution. The assembly has a layer of polyacrylamide hydrogel overlying a separate layer of resin embedded in gel. Cr(III) species accumulate exclusively and quantitatively in the resin layer, while Cr(VI) species equilibrate with both hydrogel and resin layers. The species are separated by peeling the two layers apart. Chromium is then eluted from each of the two layers. Cr(III) and Cr(VI) were determined quantitatively in standard, mixed solutions by in situ separation with DGT and detection by GF-AAS. With this method, Cr(III) is typically preconcentrated by a factor of 10 over a 24 h deployment, and limits of detection of 8 ng/L Cr(III) and 0.3 micro g/L Cr(VI) were achieved. Due to the inbuilt preconcentration of Cr(III), the technique is particularly good at measuring low concentrations of Cr(III) in the presence of an excess of Cr(VI). Measurements were performed in three soils with various levels of chromium contamination. A concentration of 3 micro g/L of labile Cr(III) was measured reproducibly in the presence of 290 micro g/L of unreactive Cr species and 0.2 micro g/L of labile Cr(III) was measured in the presence of 24 micro g/L of unreactive Cr. The unique feature of the method is that the separation of Cr(III) from Cr(VI) occurs in situ. The Cr species are then stable in the resin and gel prior to analysis, eliminating the artefacts associated with sampling and storage, which are particularly prevalent for redox-sensitive elements. Therefore, it has great potential for assessing Cr(III) and Cr(VI) concentrations in situ in environments near redox boundaries where possible dynamic changes in Cr(III) and Cr(VI) concentrations are occurring."
1509592,Jensen and  Børve 2002,Reduction of chromium in ethylene polymerisation using bis(imido)chromium(VI) catalyst precursors,"Hybrid density functional calculations on [Cr(NR)2C3H7(C2H4)]+ (R = H, tBu) have revealed a facile reductive elimination reaction involving beta-hydrogen transfer from the alkyl chain, suggesting that the active species in ethylene polymerisation with bis(imido)chromium(VI) precursors contains a reduced chromium atom.","Reduction of chromium in ethylene polymerisation using bis(imido)chromium(VI) catalyst precursors Abs: Hybrid density functional calculations on [Cr(NR)2C3H7(C2H4)]+ (R = H, tBu) have revealed a facile reductive elimination reaction involving beta-hydrogen transfer from the alkyl chain, suggesting that the active species in ethylene polymerisation with bis(imido)chromium(VI) precursors contains a reduced chromium atom."
1509591,Roundhill and  Koch 2002,Methods and techniques for the selective extraction and recovery of oxoanions,"An important goal in environmental chemistry is the extraction of metals that are toxic or radioactive from soils and waters. For many such metals, the problem is solved by designing compounds with coordination sites that are specific for that particular metal. For cases such as oxoanions, however, where the inorganic center is already fully coordinated by oxygens, different strategies need to be used. Chromate, phosphate, selenate, pertechnetate, and aluminate are such anions. These species are problematic contaminants in soils and waters because they are either toxic, environmentally undesirable, or radioactive. Furthermore, under both acidic and basic conditions, the coordination positions of these oxoanions are occupied by oxygens. Chromium(VI) as either chromate or dichromate presents a particular problem because it is a strong oxidizing agent. In this review the different methods of extracting this group of pseudotetrahedral oxoanions are discussed, along with the individual advantages and limitations of each strategy.","Methods and techniques for the selective extraction and recovery of oxoanions Abs: An important goal in environmental chemistry is the extraction of metals that are toxic or radioactive from soils and waters. For many such metals, the problem is solved by designing compounds with coordination sites that are specific for that particular metal. For cases such as oxoanions, however, where the inorganic center is already fully coordinated by oxygens, different strategies need to be used. Chromate, phosphate, selenate, pertechnetate, and aluminate are such anions. These species are problematic contaminants in soils and waters because they are either toxic, environmentally undesirable, or radioactive. Furthermore, under both acidic and basic conditions, the coordination positions of these oxoanions are occupied by oxygens. Chromium(VI) as either chromate or dichromate presents a particular problem because it is a strong oxidizing agent. In this review the different methods of extracting this group of pseudotetrahedral oxoanions are discussed, along with the individual advantages and limitations of each strategy."
1509590,Morais et al. 2002,A flow system with in-line blank correction applied to the spectrophotometric determination of total iron and chromium (VI) in wastewaters,"A flow system using the sample as the carrier with a propulsion device located after the detector is presented. This approach allows the correction of the intrinsic color of the sample, as it provides baseline adjustment for each sample. A confluence situated just after the selection valve allows the sample composition to be adjusted for the colorimetric measurement. The developed methodology was applied to the colorimetric determination of total Fe and Cr (VI) in wastewaters at 0.1-6.0 mg L-1 and 0.03-1.0 mg L-1, respectively. RSDs lower than 3% and a sampling rate of approximately 40 h-1 were obtained.","A flow system with in-line blank correction applied to the spectrophotometric determination of total iron and chromium (VI) in wastewaters Abs: A flow system using the sample as the carrier with a propulsion device located after the detector is presented. This approach allows the correction of the intrinsic color of the sample, as it provides baseline adjustment for each sample. A confluence situated just after the selection valve allows the sample composition to be adjusted for the colorimetric measurement. The developed methodology was applied to the colorimetric determination of total Fe and Cr (VI) in wastewaters at 0.1-6.0 mg L-1 and 0.03-1.0 mg L-1, respectively. RSDs lower than 3% and a sampling rate of approximately 40 h-1 were obtained."
1509589,Shakoori and  Muneer 2002,Copper-resistant bacteria from industrial effluents and their role in remediation of heavy metals in wastewater,"Six copper-resistant bacterial strains were isolated from wastewater of tanneries of Kasur and Rohi Nala. Two strains tolerated copper at 380 mg/L, four up to 400 mg/L. Three strains were identified as members of the genus Salmonella; one strain was identified as Streptococcus pyrogenes, one as Vagococcus fluvialis and the last was identified as Escherichia coli. The pH and temperature optimum for two of them were 7.0 and 30 degrees C, respectively; four strains had corresponding optima at 7.5 and 37 degrees C, respectively. All bacterial isola-tes showed resistance against Ag+ (280-350 mg/L), Co2+ (200-420), CrVI (280-400), Cd2+ (250-350), Hg2+ (110-200), Mn2+ (300-380), Pb2+ (300-400), Sn2+ (480-520) and Zn2+ (300-450). Large-sized plasmids (&gt; 20 kb), were detected in all of the strains. After the isolates were cured of plasmids with ethidium bromide, the efficiency of curing was estimated in the range of 60-90%. Reference strain of E. coli was transformed with the plasmids of the bacterial isolates which grew in Luria-Bertani medium containing 100 mg/L Cu2+. The capability to adsorb and afterwards accumulate Cu2+ inside their cells was assayed by atomic absorption spectrophotometer; all bacterial cells had the ability to adsorb 50-80% of the Cu2+ and accumulate 30-45% Cu2+ inside them after 1 d of incubation.","Copper-resistant bacteria from industrial effluents and their role in remediation of heavy metals in wastewater Abs: Six copper-resistant bacterial strains were isolated from wastewater of tanneries of Kasur and Rohi Nala. Two strains tolerated copper at 380 mg/L, four up to 400 mg/L. Three strains were identified as members of the genus Salmonella; one strain was identified as Streptococcus pyrogenes, one as Vagococcus fluvialis and the last was identified as Escherichia coli. The pH and temperature optimum for two of them were 7.0 and 30 degrees C, respectively; four strains had corresponding optima at 7.5 and 37 degrees C, respectively. All bacterial isola-tes showed resistance against Ag+ (280-350 mg/L), Co2+ (200-420), CrVI (280-400), Cd2+ (250-350), Hg2+ (110-200), Mn2+ (300-380), Pb2+ (300-400), Sn2+ (480-520) and Zn2+ (300-450). Large-sized plasmids (&gt; 20 kb), were detected in all of the strains. After the isolates were cured of plasmids with ethidium bromide, the efficiency of curing was estimated in the range of 60-90%. Reference strain of E. coli was transformed with the plasmids of the bacterial isolates which grew in Luria-Bertani medium containing 100 mg/L Cu2+. The capability to adsorb and afterwards accumulate Cu2+ inside their cells was assayed by atomic absorption spectrophotometer; all bacterial cells had the ability to adsorb 50-80% of the Cu2+ and accumulate 30-45% Cu2+ inside them after 1 d of incubation."
1509588,Francisco et al. 2002,Diversity of chromium-resistant and -reducing bacteria in a chromium-contaminated activated sludge,"<strong>AIMS: </strong>This study attempts to establish a relationship between the Cr(VI) resistance of the culturable microbial community and the Cr(VI) resistance and Cr(VI)-reducing ability of representative strains of each population, in order to assess whether these are exclusive characteristics of one microbial group or abilities shared among many groups.<br /><br /><strong>METHODS AND RESULTS: </strong>A group of 48 Cr(VI)-resistant isolates, with different colony types, was isolated from chromium-contaminated activated sludge. Sodium dodecyl sulphate-polyacrylamide gel electrophoresis protein patterns and fatty acid methyl ester analysis identified six populations, representing 54% of the isolated bacteria, as belonging to the genera Acinetobacter and Ochrobactrum. The remaining populations included strains identified as species of the beta-Proteobacteria and high G + C Gram-positive bacteria. The Cr(VI) resistance and reduction ability of the strains were tested. All but two isolates grew in the presence of 1 mmol l(-1) Cr(VI). During enrichment, all isolates were able to survive to 2 mmol l(-1) Cr(VI) and complete Cr(VI) reduction was achieved. Representative strains of each population were able to partially reduce (5.4-39.1%) the Cr(VI) present in the growth medium.<br /><br /><strong>CONCLUSIONS: </strong>Most of the identified isolates have never been reported to be Cr(VI)-resistant and/or Cr(VI)-reducing strains. The mechanisms of Cr(VI) resistance and reduction may differ from group to group; therefore, it is evident that both Cr(VI) resistance and reduction are shared abilities and not an exclusive characteristic of a single group, possibly reflecting horizontal genetic transfer resulting from selective pressure in this contaminated environment.<br /><br /><strong>SIGNIFICANCE AND IMPACT OF THE STUDY: </strong>To our knowledge, this is the first study of a microbial community under chronic chromate stress and, as the success of microbial-based metal remediation technologies requires a better understanding of the microbial community and the population response to metal stress, it may contribute to the implementation of a strategy of bioremediation of chromate-contaminated environments.","Diversity of chromium-resistant and -reducing bacteria in a chromium-contaminated activated sludge Abs: <strong>AIMS: </strong>This study attempts to establish a relationship between the Cr(VI) resistance of the culturable microbial community and the Cr(VI) resistance and Cr(VI)-reducing ability of representative strains of each population, in order to assess whether these are exclusive characteristics of one microbial group or abilities shared among many groups.<br /><br /><strong>METHODS AND RESULTS: </strong>A group of 48 Cr(VI)-resistant isolates, with different colony types, was isolated from chromium-contaminated activated sludge. Sodium dodecyl sulphate-polyacrylamide gel electrophoresis protein patterns and fatty acid methyl ester analysis identified six populations, representing 54% of the isolated bacteria, as belonging to the genera Acinetobacter and Ochrobactrum. The remaining populations included strains identified as species of the beta-Proteobacteria and high G + C Gram-positive bacteria. The Cr(VI) resistance and reduction ability of the strains were tested. All but two isolates grew in the presence of 1 mmol l(-1) Cr(VI). During enrichment, all isolates were able to survive to 2 mmol l(-1) Cr(VI) and complete Cr(VI) reduction was achieved. Representative strains of each population were able to partially reduce (5.4-39.1%) the Cr(VI) present in the growth medium.<br /><br /><strong>CONCLUSIONS: </strong>Most of the identified isolates have never been reported to be Cr(VI)-resistant and/or Cr(VI)-reducing strains. The mechanisms of Cr(VI) resistance and reduction may differ from group to group; therefore, it is evident that both Cr(VI) resistance and reduction are shared abilities and not an exclusive characteristic of a single group, possibly reflecting horizontal genetic transfer resulting from selective pressure in this contaminated environment.<br /><br /><strong>SIGNIFICANCE AND IMPACT OF THE STUDY: </strong>To our knowledge, this is the first study of a microbial community under chronic chromate stress and, as the success of microbial-based metal remediation technologies requires a better understanding of the microbial community and the population response to metal stress, it may contribute to the implementation of a strategy of bioremediation of chromate-contaminated environments."
1509587,Milacic et al. 2002,Determination of Cr(VI) in welding fumes by anion-exchange fast protein liquid chromatography with electrothermal atomic absorption spectrometric detection,"The applicability of an anion-exchange fast protein liquid chromatographic-electrothermal atomic absorption spectrometric procedure (FPLC-ETAAS) was investigated for the determination of Cr(VI) in welding fumes after alkaline extraction of aerosols loaded on filters. Gas tungsten arc welding (GTAW) of stainless steel was applied. Samples of welding fumes were collected during regular welding on polycarbonate membrane filters of 8 microm and 0.4 microm pore size (inhalable and respirable aerosols). Alkaline extraction (2% NaOH-3% Na2CO3) of filters in a heated ultrasonic bath was applied to leach Cr from the airborne particulate matter. 0.5 cm3 of sample extract was then injected onto an anion-exchange FPLC column. Tris-HCl buffer (0.005 mol dm(-3), pH 8.0) and the same buffer with NaCl (0.5 mol dm(-3)) were employed in gradient elution (15 min, flow rate 1 cm3 min(-1)). The separated Cr species were determined &quot;off line&quot; by ETAAS in 0.5 cm3 fractions. Cr(VI) was reproducibly and quantitatively eluted from 12.0 to 13.0 min with a maximum peak at 12.5 min. Good repeatability of measurement (+/-3.0%) of alkaline extracts was obtained for Cr(VI). The LOD (3s) was found to be 0.035 microg m(-3) Cr(VI), when 2 m3 of aerosols were collected on the filter. Validation of the procedure was performed by spiking alkaline extracts and by the analysis of standard reference material CRM 545, Cr(VI) in welding dust loaded on a filter. The technique was successfully applied for the determination of Cr(VI) in welding fumes.","Determination of Cr(VI) in welding fumes by anion-exchange fast protein liquid chromatography with electrothermal atomic absorption spectrometric detection Abs: The applicability of an anion-exchange fast protein liquid chromatographic-electrothermal atomic absorption spectrometric procedure (FPLC-ETAAS) was investigated for the determination of Cr(VI) in welding fumes after alkaline extraction of aerosols loaded on filters. Gas tungsten arc welding (GTAW) of stainless steel was applied. Samples of welding fumes were collected during regular welding on polycarbonate membrane filters of 8 microm and 0.4 microm pore size (inhalable and respirable aerosols). Alkaline extraction (2% NaOH-3% Na2CO3) of filters in a heated ultrasonic bath was applied to leach Cr from the airborne particulate matter. 0.5 cm3 of sample extract was then injected onto an anion-exchange FPLC column. Tris-HCl buffer (0.005 mol dm(-3), pH 8.0) and the same buffer with NaCl (0.5 mol dm(-3)) were employed in gradient elution (15 min, flow rate 1 cm3 min(-1)). The separated Cr species were determined &quot;off line&quot; by ETAAS in 0.5 cm3 fractions. Cr(VI) was reproducibly and quantitatively eluted from 12.0 to 13.0 min with a maximum peak at 12.5 min. Good repeatability of measurement (+/-3.0%) of alkaline extracts was obtained for Cr(VI). The LOD (3s) was found to be 0.035 microg m(-3) Cr(VI), when 2 m3 of aerosols were collected on the filter. Validation of the procedure was performed by spiking alkaline extracts and by the analysis of standard reference material CRM 545, Cr(VI) in welding dust loaded on a filter. The technique was successfully applied for the determination of Cr(VI) in welding fumes."
1509586,Stepniewska and  Bucior 2001,The conditions favourable to oxidation of Cr (III) to Cr (VI) and the presence of chromium forms on the area contaminated by tannery wastes,"The aim of this paper was to study the conditions favourable to Cr (III) oxidation such as: type of soil, soil water content, presence of organic matter and three oxidisers (MnO2, NaNO3 and Fe2O3). Also concentrations of different species of chromium in water and soils were examined in the area contaminated with tannery wastes containing 5-10% of Cr2O3. The action of oxidisers was studied in batch experiment for 2 h at room temperature at pH=5.35+/-0.2. The highest level of oxidised trivalent chromium was registered for soil with the lowest content of organic matter (0.72% C(org)), when Cr (III) was oxidised by MnO2, Fe2O3 and NaNO3 did not show properties towards Cr (III) oxidation under the conditions described.","The conditions favourable to oxidation of Cr (III) to Cr (VI) and the presence of chromium forms on the area contaminated by tannery wastes Abs: The aim of this paper was to study the conditions favourable to Cr (III) oxidation such as: type of soil, soil water content, presence of organic matter and three oxidisers (MnO2, NaNO3 and Fe2O3). Also concentrations of different species of chromium in water and soils were examined in the area contaminated with tannery wastes containing 5-10% of Cr2O3. The action of oxidisers was studied in batch experiment for 2 h at room temperature at pH=5.35+/-0.2. The highest level of oxidised trivalent chromium was registered for soil with the lowest content of organic matter (0.72% C(org)), when Cr (III) was oxidised by MnO2, Fe2O3 and NaNO3 did not show properties towards Cr (III) oxidation under the conditions described."
1509585,Divakaran et al. 2002,Note on the methods for determination of chromic oxide in shrimp feeds,"Chromic oxide is used as an inert marker to measure apparent digestibility of feeds in insects, terrestrial, and aquatic animals. Quantitative determination of chromic oxide content in the sample requires the oxidation of water insoluble trivalent chromic oxide to its water-soluble hexavalent form. The two commonly used oxidizing agents are 70% perchloric acid or a mixture of sodium molybdate, sulfuric, and perchloric acid. Chromic oxide content of the oxidized solution is then measured against known standards either directly by spectrophotometry in the visible range at 350, 370, or 440 nm or after forming a colored complex with diphenylcarbazide (DPC) by colorimetry at 540 nm. This study compared the two methods of oxidation followed by spectrophotometry at the three wavelengths and by DPC colorimetry. DPC colorimetry gave precise results than the direct measurement of dichromate ion, irrespective of the method of oxidation used. Ash from samples oxidized by perchloric acid and quantified by DPC colorimetry gave a better measure of actual chromic oxide content as compared to the other methods tested.","Note on the methods for determination of chromic oxide in shrimp feeds Abs: Chromic oxide is used as an inert marker to measure apparent digestibility of feeds in insects, terrestrial, and aquatic animals. Quantitative determination of chromic oxide content in the sample requires the oxidation of water insoluble trivalent chromic oxide to its water-soluble hexavalent form. The two commonly used oxidizing agents are 70% perchloric acid or a mixture of sodium molybdate, sulfuric, and perchloric acid. Chromic oxide content of the oxidized solution is then measured against known standards either directly by spectrophotometry in the visible range at 350, 370, or 440 nm or after forming a colored complex with diphenylcarbazide (DPC) by colorimetry at 540 nm. This study compared the two methods of oxidation followed by spectrophotometry at the three wavelengths and by DPC colorimetry. DPC colorimetry gave precise results than the direct measurement of dichromate ion, irrespective of the method of oxidation used. Ash from samples oxidized by perchloric acid and quantified by DPC colorimetry gave a better measure of actual chromic oxide content as compared to the other methods tested."
1509584,Shemirani and  Rajabi 2001,Preconcentration of chromium (III) and speciation of chromium by electrothermal atomic absorption spectrometry using cellulose adsorbent,"A simple and sensitive method has been developed for species selective determination of chromium(III) and chromium(VI) in water by electrothermal atomic absorption spectrometry. The procedure is based on selective absorption of Cr(III) on a cellulose micro column (pH 11, 0.5 mol L(-1) NaCl). Total chromium was subsequently determined after appropriate reduction of Cr(VI) to Cr(III). Recoveries of more than 97% were found. A concentration factor of 100 was achieved. The relative standard deviations (n=10) at the 40 ng L(-1) level for chromium(III) and chromium(VI) were 2.3% and 1.8% and corresponding limits of detection (based on 36) were 1.8 ng L(-1) and 5.1 ng L(-1), respectively. No interference effects have been observed from other investigated species and the method has been successfully applied to natural water samples.","Preconcentration of chromium (III) and speciation of chromium by electrothermal atomic absorption spectrometry using cellulose adsorbent Abs: A simple and sensitive method has been developed for species selective determination of chromium(III) and chromium(VI) in water by electrothermal atomic absorption spectrometry. The procedure is based on selective absorption of Cr(III) on a cellulose micro column (pH 11, 0.5 mol L(-1) NaCl). Total chromium was subsequently determined after appropriate reduction of Cr(VI) to Cr(III). Recoveries of more than 97% were found. A concentration factor of 100 was achieved. The relative standard deviations (n=10) at the 40 ng L(-1) level for chromium(III) and chromium(VI) were 2.3% and 1.8% and corresponding limits of detection (based on 36) were 1.8 ng L(-1) and 5.1 ng L(-1), respectively. No interference effects have been observed from other investigated species and the method has been successfully applied to natural water samples."
1509583,Guha et al. 2001,Kinetics of chromium (VI) reduction by a type strain Shewanella alga under different growth conditions,"We conducted kinetic batch experiments to determine the reduction of Chromium(VI) by a type strain of Shewanella alga (BrY-MT) ATCC 55627. Chromium(VI) was reduced to Chromium(III) by BrY-MT grown in three different substrates: BHIB (brain heart infusion broth), TSB (tryptic soy broth), and M9 (minimum broth). Four different Cr(VI) concentrations 4.836, 10.00, 37.125, and 260.00 mg l-1 were reduced at different rates by BrY-MT in both aerobic and anaerobic conditions. BrY-MT grown in BHIB reduced the maximum amount of Cr(VI) followed by TSB and M9. Carbondioxide produced from bacterial respiration varied with and without Cr(VI) under both aerobic and anaerobic conditions. The Cr(VI) reduction data under anaerobic condition was fitted by a monod model to determine the bacterial kinetic parameters. The kinetic parameters determined by fitting the anaerobic experimental data were used to run a forward simulation for experiments conducted under aerobic conditions. The monod model was modified to account for an inhibition parameter for the Cr(VI) experiment at 260 mg l-1. All the parameters varied within a narrow range, and were distinct for different substrates. Our studies show that, successful in situ bioremediation of Cr(VI) is depended on the type of substrates (electron donors) and the concentration of Cr(VI) in geologic medium.","Kinetics of chromium (VI) reduction by a type strain Shewanella alga under different growth conditions Abs: We conducted kinetic batch experiments to determine the reduction of Chromium(VI) by a type strain of Shewanella alga (BrY-MT) ATCC 55627. Chromium(VI) was reduced to Chromium(III) by BrY-MT grown in three different substrates: BHIB (brain heart infusion broth), TSB (tryptic soy broth), and M9 (minimum broth). Four different Cr(VI) concentrations 4.836, 10.00, 37.125, and 260.00 mg l-1 were reduced at different rates by BrY-MT in both aerobic and anaerobic conditions. BrY-MT grown in BHIB reduced the maximum amount of Cr(VI) followed by TSB and M9. Carbondioxide produced from bacterial respiration varied with and without Cr(VI) under both aerobic and anaerobic conditions. The Cr(VI) reduction data under anaerobic condition was fitted by a monod model to determine the bacterial kinetic parameters. The kinetic parameters determined by fitting the anaerobic experimental data were used to run a forward simulation for experiments conducted under aerobic conditions. The monod model was modified to account for an inhibition parameter for the Cr(VI) experiment at 260 mg l-1. All the parameters varied within a narrow range, and were distinct for different substrates. Our studies show that, successful in situ bioremediation of Cr(VI) is depended on the type of substrates (electron donors) and the concentration of Cr(VI) in geologic medium."
1509582,Chen et al. 2001,"Separation of chromium (III) and chromium (VI) by capillary electrophoresis using 2,6-pyridinedicarboxylic acid as a pre-column complexation agent","A simple method was developed for the simultaneous determination of Cr(III) and Cr(VI) by capillary zone electrophoresis (CZE), where Cr(III) was chelated with ligands to form anionic complexes. Nitrilotriacetic acid, N-2-hydroxyethylenediaminetriacetic acid, ethylenediaminetetraacetic acid, diethylenetriaminepentaacetic acid, and 2,6-pyridinedicarboxylic acid (PDCA) were investigated as Cr(III) complexing ligands. Of all the ligands studied, 2,6-PDCA with Cr(III) gave the largest UV response and high selectivity for Cr(III). In addition, the condition for pre-column derivatization, including pH, concentration ratio [Cr(III)/2,6-PDCA] and the stability of Cr(III) complexes were also examined. The separation of anionic forms of Cr(III) and Cr(VI) was achieved using co-CZE with UV detection at 185 nm. The electrolyte contained 30 mM phosphate, 0.5 mM tetradecyltrimethylammonium bromide, 0.1 mM 2,6-PDCA and 15% (v/v) acetonitrile at pH 6.4. The detection limits were 2 microM for Cr(III) and 3 microM for Cr(VI) and linear plots were obtained in a concentration range of 5-200 microM. The utility of the method was demonstrated for the determination of Cr(III) and Cr(VI) in contaminated soils.","Separation of chromium (III) and chromium (VI) by capillary electrophoresis using 2,6-pyridinedicarboxylic acid as a pre-column complexation agent Abs: A simple method was developed for the simultaneous determination of Cr(III) and Cr(VI) by capillary zone electrophoresis (CZE), where Cr(III) was chelated with ligands to form anionic complexes. Nitrilotriacetic acid, N-2-hydroxyethylenediaminetriacetic acid, ethylenediaminetetraacetic acid, diethylenetriaminepentaacetic acid, and 2,6-pyridinedicarboxylic acid (PDCA) were investigated as Cr(III) complexing ligands. Of all the ligands studied, 2,6-PDCA with Cr(III) gave the largest UV response and high selectivity for Cr(III). In addition, the condition for pre-column derivatization, including pH, concentration ratio [Cr(III)/2,6-PDCA] and the stability of Cr(III) complexes were also examined. The separation of anionic forms of Cr(III) and Cr(VI) was achieved using co-CZE with UV detection at 185 nm. The electrolyte contained 30 mM phosphate, 0.5 mM tetradecyltrimethylammonium bromide, 0.1 mM 2,6-PDCA and 15% (v/v) acetonitrile at pH 6.4. The detection limits were 2 microM for Cr(III) and 3 microM for Cr(VI) and linear plots were obtained in a concentration range of 5-200 microM. The utility of the method was demonstrated for the determination of Cr(III) and Cr(VI) in contaminated soils."
1509580,Xiao et al. 2001,Synchronous fluorescence and absorbance dynamic liquid drop sensor for cr(VI) determination at the femtomole level,"A novel synchronous fluorimetric and absorptiometric technique based on dynamic liquid drops coupled with flow injection is described for the determination of chromium(VI) in aqueous solutions. Drops formed continuously at the end of a quartz capillary tube serve as reactor and optical cell. The reaction between chromium(VI) and 3,3',5,5'-tetramethylbenzidine dichloride (TMB-d) results in a significant decrease in fluorescence and transmitted light intensity, proportional to the logarithm of the concentration of chromium(VI). The transmitted light and fluorescence emission are detected in counter and perpendicular positions of the excitation light by a photomultipler tube and photodiode, respectively. In HCl-NaOAc buffer solution (pH 3.29), the sensor has a wide linear calibration range of 2 x 10(-8)-1 x 10(-4) mol l(-1) chromium(VI) with an absolute mass detection limit of 12.88 fmol.","Synchronous fluorescence and absorbance dynamic liquid drop sensor for cr(VI) determination at the femtomole level Abs: A novel synchronous fluorimetric and absorptiometric technique based on dynamic liquid drops coupled with flow injection is described for the determination of chromium(VI) in aqueous solutions. Drops formed continuously at the end of a quartz capillary tube serve as reactor and optical cell. The reaction between chromium(VI) and 3,3',5,5'-tetramethylbenzidine dichloride (TMB-d) results in a significant decrease in fluorescence and transmitted light intensity, proportional to the logarithm of the concentration of chromium(VI). The transmitted light and fluorescence emission are detected in counter and perpendicular positions of the excitation light by a photomultipler tube and photodiode, respectively. In HCl-NaOAc buffer solution (pH 3.29), the sensor has a wide linear calibration range of 2 x 10(-8)-1 x 10(-4) mol l(-1) chromium(VI) with an absolute mass detection limit of 12.88 fmol."
1509579,Izumi et al. 2001,Site-selective XAFS spectroscopy tuned to surface active sites of Cu/ZnO and Cr/SiO2 catalysts,"XAFS (X-ray absorption fine structure) spectra were measured by using the fluorescence spectrometer for the emitted X-ray from sample. The chemical shifts between Cu0 and Cu1 and between CrIII and CrVI were evaluated. Tuning the fluorescence spectrometer to each energy, the Cu0 and CuI site-selective XANES for Cu/ZnO catalyst were measured. The first one was similar to the XANES of Cu metal and the second one was the 5 : 5 average of XANES for CuI sites + Cu metal. The population ratio of copper site of the Cu/ZnO catalyst was found to be Cu metal: Cu2O : CuI atomically dispersed on surface = 70(+/-23) : 22(+/-14) : 8(+/-5). Site-selective XANES for CrIII site of Cr/SiO2 catalyst was also studied.","Site-selective XAFS spectroscopy tuned to surface active sites of Cu/ZnO and Cr/SiO2 catalysts Abs: XAFS (X-ray absorption fine structure) spectra were measured by using the fluorescence spectrometer for the emitted X-ray from sample. The chemical shifts between Cu0 and Cu1 and between CrIII and CrVI were evaluated. Tuning the fluorescence spectrometer to each energy, the Cu0 and CuI site-selective XANES for Cu/ZnO catalyst were measured. The first one was similar to the XANES of Cu metal and the second one was the 5 : 5 average of XANES for CuI sites + Cu metal. The population ratio of copper site of the Cu/ZnO catalyst was found to be Cu metal: Cu2O : CuI atomically dispersed on surface = 70(+/-23) : 22(+/-14) : 8(+/-5). Site-selective XANES for CrIII site of Cr/SiO2 catalyst was also studied."
1509578,Reiter 1999,Oxidative damage to nuclear DNA: amelioration by melatonin. NEL Review,"The indoleamine melatonin, a product of tryptophan metabolism in the pineal gland, is a free radical scavenger and antioxidant. This brief review summarizes melatonin's ability to protect nuclear DNA from oxidative damage. Using a variety of different cytogenetic, biochemical and molecular biological methods, a number of investigators have demonstrated melatonin's ability to protect DNA from the physical agent ionizing radiation, the herbicide paraquat, the carcinogen safrole, the excitotoxin kainic acid, the heavy metal chromium (VI), and a wide number of mutagens. Since these agents damage DNA because they generate free radicals, the observations are consistent with melatonin being a radical scavenger and antioxidant.","Oxidative damage to nuclear DNA: amelioration by melatonin. NEL Review Abs: The indoleamine melatonin, a product of tryptophan metabolism in the pineal gland, is a free radical scavenger and antioxidant. This brief review summarizes melatonin's ability to protect nuclear DNA from oxidative damage. Using a variety of different cytogenetic, biochemical and molecular biological methods, a number of investigators have demonstrated melatonin's ability to protect DNA from the physical agent ionizing radiation, the herbicide paraquat, the carcinogen safrole, the excitotoxin kainic acid, the heavy metal chromium (VI), and a wide number of mutagens. Since these agents damage DNA because they generate free radicals, the observations are consistent with melatonin being a radical scavenger and antioxidant."
1509577,Kim et al. 2001,Chromium(VI) reduction by hydrogen sulfide in aqueous media: stoichiometry and kinetics,"The objective of this work was to investigate the reaction stoichiometry, kinetics, and mechanism for Cr(VI) reduction by hydrogen sulfide in the aqueous phase. Batch experiments with excess [Cr(VI)] over [H2S]T indicated that the molar amount of sulfide required for the reduction of 1 M Cr(VI) was 1.5, suggesting the following stoichiometry: 2CrO4(2-) + 3H2S + 4H+--&gt;2Cr(OH)3(s) + 3S(s) + 2H2O. Further study with transmission electron microscopy (TEM) and energy-dispersive X-ray spectroscopy (EDS) confirmed that chromium hydroxide and elemental sulfur were the stable products. The kinetics of Cr(VI) reduction by hydrogen sulfide was measured under various initial concentrations of Cr(VI) and sulfide as well as pH values controlled by HEPES, phosphate, and borate buffers. Results showed that the overall reaction was second-order, i.e., first-order with respect to Cr(VI) and first-order to sulfide. The reaction rate increased as pH was decreased, and the pH dependence correlated well with the fraction of fully protonated sulfide (H2S) in the pH range of 6.5-10. The nature of buffers did not influence the reaction rate significantly in the homogeneous system. The reaction kinetics could be interpreted by a three-step mechanism: formation of an inner-sphere chromate-sulfide intermediate complex ((H2O4CrVIS)2-), intramolecular electron transfer to form Cr(IV) species, and subsequent fast reactions leading to Cr(III).","Chromium(VI) reduction by hydrogen sulfide in aqueous media: stoichiometry and kinetics Abs: The objective of this work was to investigate the reaction stoichiometry, kinetics, and mechanism for Cr(VI) reduction by hydrogen sulfide in the aqueous phase. Batch experiments with excess [Cr(VI)] over [H2S]T indicated that the molar amount of sulfide required for the reduction of 1 M Cr(VI) was 1.5, suggesting the following stoichiometry: 2CrO4(2-) + 3H2S + 4H+--&gt;2Cr(OH)3(s) + 3S(s) + 2H2O. Further study with transmission electron microscopy (TEM) and energy-dispersive X-ray spectroscopy (EDS) confirmed that chromium hydroxide and elemental sulfur were the stable products. The kinetics of Cr(VI) reduction by hydrogen sulfide was measured under various initial concentrations of Cr(VI) and sulfide as well as pH values controlled by HEPES, phosphate, and borate buffers. Results showed that the overall reaction was second-order, i.e., first-order with respect to Cr(VI) and first-order to sulfide. The reaction rate increased as pH was decreased, and the pH dependence correlated well with the fraction of fully protonated sulfide (H2S) in the pH range of 6.5-10. The nature of buffers did not influence the reaction rate significantly in the homogeneous system. The reaction kinetics could be interpreted by a three-step mechanism: formation of an inner-sphere chromate-sulfide intermediate complex ((H2O4CrVIS)2-), intramolecular electron transfer to form Cr(IV) species, and subsequent fast reactions leading to Cr(III)."
1509576,Cervantes et al. 2001,Interactions of chromium with microorganisms and plants,"Chromium is a highly toxic non-essential metal for microorganisms and plants. Due to its widespread industrial use, chromium (Cr) has become a serious pollutant in diverse environmental settings. The hexavalent form of the metal, Cr(VI), is considered a more toxic species than the relatively innocuous and less mobile Cr(III) form. The presence of Cr in the environment has selected microbial and plant variants able to tolerate high levels of Cr compounds. The diverse Cr-resistance mechanisms displayed by microorganisms, and probably by plants, include biosorption, diminished accumulation, precipitation, reduction of Cr(VI) to Cr(III), and chromate efflux. Some of these systems have been proposed as potential biotechnological tools for the bioremediation of Cr pollution. In this review we summarize the interactions of bacteria, algae, fungi and plants with Cr and its compounds.","Interactions of chromium with microorganisms and plants Abs: Chromium is a highly toxic non-essential metal for microorganisms and plants. Due to its widespread industrial use, chromium (Cr) has become a serious pollutant in diverse environmental settings. The hexavalent form of the metal, Cr(VI), is considered a more toxic species than the relatively innocuous and less mobile Cr(III) form. The presence of Cr in the environment has selected microbial and plant variants able to tolerate high levels of Cr compounds. The diverse Cr-resistance mechanisms displayed by microorganisms, and probably by plants, include biosorption, diminished accumulation, precipitation, reduction of Cr(VI) to Cr(III), and chromate efflux. Some of these systems have been proposed as potential biotechnological tools for the bioremediation of Cr pollution. In this review we summarize the interactions of bacteria, algae, fungi and plants with Cr and its compounds."
1509575,Nkhalambayausi-Chirwa and  Wang 2001,Simultaneous chromium(VI) reduction and phenol degradation in a fixed-film coculture bioreactor: reactor performance,"Simultaneous Cr(VI) reduction and phenol degradation was observed in a fixed-film bioreactor consisting of a coculture of phenol-degrading bacteria, Pseudomonas putida DMP-1, and Cr(VI)-reducing bacteria, Escherichia coli ATCC 33456. Near complete Cr(VI) reduction and phenol degradation was observed during steady-state operation of the reactor under loadings of 5-21 mg Cr(VI) l-1 d-1 and 840-3350 mg phenol l-1 d-1. 2-hydroxymuconic semialdehyde (2HMSA), succinate, and acetate were the detected steady-state organic acid metabolites which accounted for 13-23% of TOC in the effluent. Optimum Cr(VI) reduction rate was observed under a Cr(VI) loading of approximately 26.5 mg Cr(VI) l-1 d-1 just before system overload. System overload was characterized by the increase in effluent Cr(VI) and phenol concentrations. System resilience to Cr(VI) toxicity was demonstrated by rapid recovery of biological activity and reduced effluent Cr(VI) and phenol concentrations after off-loading the system from overloaded conditions.","Simultaneous chromium(VI) reduction and phenol degradation in a fixed-film coculture bioreactor: reactor performance Abs: Simultaneous Cr(VI) reduction and phenol degradation was observed in a fixed-film bioreactor consisting of a coculture of phenol-degrading bacteria, Pseudomonas putida DMP-1, and Cr(VI)-reducing bacteria, Escherichia coli ATCC 33456. Near complete Cr(VI) reduction and phenol degradation was observed during steady-state operation of the reactor under loadings of 5-21 mg Cr(VI) l-1 d-1 and 840-3350 mg phenol l-1 d-1. 2-hydroxymuconic semialdehyde (2HMSA), succinate, and acetate were the detected steady-state organic acid metabolites which accounted for 13-23% of TOC in the effluent. Optimum Cr(VI) reduction rate was observed under a Cr(VI) loading of approximately 26.5 mg Cr(VI) l-1 d-1 just before system overload. System overload was characterized by the increase in effluent Cr(VI) and phenol concentrations. System resilience to Cr(VI) toxicity was demonstrated by rapid recovery of biological activity and reduced effluent Cr(VI) and phenol concentrations after off-loading the system from overloaded conditions."
1509574,Schlautman and  Han 2001,Effects of pH and dissolved oxygen on the reduction of hexavalent chromium by dissolved ferrous iron in poorly buffered aqueous systems,"The effects of pH and dissolved oxygen (DO) on the reduction of Cr(VI) by dissolved Fe(II) were investigated for aqueous solutions having relatively low buffering capacities. All solutions were maintained at a constant ionic strength (generally 0.05 M) and temperature (23 +/- 2 degrees C). For the majority of the experiments conducted, initial concentrations of Fe(II) and Cr(VI) were 50 and 20 microM, respectively, representing a deficient amount of Fe(II) (i.e. nonstoichiometric conditions). Experiments conducted in the absence and presence of DO were performed in an anaerobic chamber and in vessels open to the atmosphere, respectively. Specific initial pH values were obtained by adjusting the pH of Cr(VI) and Fe(II) stock solutions prior to their mixing or by spiking Cr(VI)-Fe(II) systems with strong base to rapidly increase the pH in situ. Consistent with previous reports, Cr(VI) reduction rates for our systems increased with increasing pH (pH ranges of 3.5-6 and 3.5-7.2 for oxic and anoxic experiments, respectively). Because of our poorly buffered experimental systems, pH values decreased over the course of the reactions which, in turn, caused decreases in the reduction rates with time. Spiking some experimental systems with NaOH to rapidly raise the pH resulted in faster rates of Cr(VI) reduction than when the pH was adjusted prior to mixing the stock solutions together; this observation is likely due to the presence of microenvironments in the reactors for which local, short-term pH values greatly exceed the equilibrium value (i.e. mixing is slower than the reduction reaction in these high pH microenvironments). The molar ratios of Fe(II) oxidized to Cr(VI) reduced were close to the expected stoichiometric value of 3 for the majority of our experimental systems, which shows that DO will not cause a serious interference in most applications using Fe(II) to reduce Cr(VI).","Effects of pH and dissolved oxygen on the reduction of hexavalent chromium by dissolved ferrous iron in poorly buffered aqueous systems Abs: The effects of pH and dissolved oxygen (DO) on the reduction of Cr(VI) by dissolved Fe(II) were investigated for aqueous solutions having relatively low buffering capacities. All solutions were maintained at a constant ionic strength (generally 0.05 M) and temperature (23 +/- 2 degrees C). For the majority of the experiments conducted, initial concentrations of Fe(II) and Cr(VI) were 50 and 20 microM, respectively, representing a deficient amount of Fe(II) (i.e. nonstoichiometric conditions). Experiments conducted in the absence and presence of DO were performed in an anaerobic chamber and in vessels open to the atmosphere, respectively. Specific initial pH values were obtained by adjusting the pH of Cr(VI) and Fe(II) stock solutions prior to their mixing or by spiking Cr(VI)-Fe(II) systems with strong base to rapidly increase the pH in situ. Consistent with previous reports, Cr(VI) reduction rates for our systems increased with increasing pH (pH ranges of 3.5-6 and 3.5-7.2 for oxic and anoxic experiments, respectively). Because of our poorly buffered experimental systems, pH values decreased over the course of the reactions which, in turn, caused decreases in the reduction rates with time. Spiking some experimental systems with NaOH to rapidly raise the pH resulted in faster rates of Cr(VI) reduction than when the pH was adjusted prior to mixing the stock solutions together; this observation is likely due to the presence of microenvironments in the reactors for which local, short-term pH values greatly exceed the equilibrium value (i.e. mixing is slower than the reduction reaction in these high pH microenvironments). The molar ratios of Fe(II) oxidized to Cr(VI) reduced were close to the expected stoichiometric value of 3 for the majority of our experimental systems, which shows that DO will not cause a serious interference in most applications using Fe(II) to reduce Cr(VI)."
1509573,Yebra and  Cespón 2000,Flow injection atomic absorption spectrometric determination of iodide using an on-line preconcentration technique,"A continuous flow atomic absorption spectrometric system was used to develop an efficient on-line preconcentration-elution procedure for the determination of iodide traces. Chromium (VI) is introduced into the flow system and is reduced to chromium (III) in acid medium proportionally to the iodide present in the sample. The Cr(III) reduced by iodide is retained on a minicolumn packed with a poly(aminophosphonic acid) chelating resin, while unreduced Cr(VI) is not retained. Reduced Cr(III) is preconcentrated by passing the sample containing iodide through the system during 3 min, and is then eluted with 0.5 mol L(-1) hydrochloric acid and determined by flame atomic absorption spectrometry (FAAS). The detection limit (3sigma) obtained is 2.5 microg L(-1). Other ions typically present in waters do not interfere. The proposed method allows the determination of iodide in the range 6-220 microg L(-1) with a relative standard deviation of 2.7% at a rate of 17 samples h(-1). The method has been applied to the determination of iodide in tap and sea waters.","Flow injection atomic absorption spectrometric determination of iodide using an on-line preconcentration technique Abs: A continuous flow atomic absorption spectrometric system was used to develop an efficient on-line preconcentration-elution procedure for the determination of iodide traces. Chromium (VI) is introduced into the flow system and is reduced to chromium (III) in acid medium proportionally to the iodide present in the sample. The Cr(III) reduced by iodide is retained on a minicolumn packed with a poly(aminophosphonic acid) chelating resin, while unreduced Cr(VI) is not retained. Reduced Cr(III) is preconcentrated by passing the sample containing iodide through the system during 3 min, and is then eluted with 0.5 mol L(-1) hydrochloric acid and determined by flame atomic absorption spectrometry (FAAS). The detection limit (3sigma) obtained is 2.5 microg L(-1). Other ions typically present in waters do not interfere. The proposed method allows the determination of iodide in the range 6-220 microg L(-1) with a relative standard deviation of 2.7% at a rate of 17 samples h(-1). The method has been applied to the determination of iodide in tap and sea waters."
1509571,Sourkouni-Argirusi 2000,A new polymer-attached reagent for the oxidation of primary and secondary alcohols,"A new, polymer-bound reagent system for the efficient oxidation of primary alcohols to aldehydes and secondary alcohols to ketones in the presence of a catalytic amount of 2,2,6, 6-tetramethyl-1-piperidinyloxyl (TEMPO) is described. In most cases, workup of this heavy metal-free oxidation is achieved by simple filtration followed by removal of the solvent. In selected examples this reagent was compared with the known polymer-bound permanganate and chromium(VI) reagents.","A new polymer-attached reagent for the oxidation of primary and secondary alcohols Abs: A new, polymer-bound reagent system for the efficient oxidation of primary alcohols to aldehydes and secondary alcohols to ketones in the presence of a catalytic amount of 2,2,6, 6-tetramethyl-1-piperidinyloxyl (TEMPO) is described. In most cases, workup of this heavy metal-free oxidation is achieved by simple filtration followed by removal of the solvent. In selected examples this reagent was compared with the known polymer-bound permanganate and chromium(VI) reagents."
1509570,Hojo et al. 2000,Direct evidence for in vivo hydroxyl radical generation in blood of mice after acute chromium(VI) intake: electron spin resonance spin-trapping investigation,"Although it is assumed from in vitro experiments that the hydroxyl radical (*OH) may be responsible for chromium(VI) toxicity/carcinogenicity, no electron spin resonance (ESR) evidence for the generation of *OH in vivo has been reported. In this study, we have employed an ESR spin-trapping technique with 5,5-dimethylpyrroline-N-oxide (DMPO), a selective *OH trap, to detect *OH in blood. The ESR spectrum of spin adduct observed in the blood of mice given 4.8 mmol Cr(VI)/kg body weight exhibited the 1:2:2:1 intensity pattern of a quartet with a hyperfine coupling constant A(N) = A(H) = 14.81 G and g-value = 2.0067. The concentration of the spin adduct detected in the blood was 7.37 microM. The adduct production was inhibited by the addition of specific *OH scavengers such as sodium benzoate and methional to the blood. The results indicate that the spin adduct is nitroxide produced by the reaction of *OH with DMPO. This is the first report of ESR evidence for the in vivo generation of *OH in mammals by Cr(VI).","Direct evidence for in vivo hydroxyl radical generation in blood of mice after acute chromium(VI) intake: electron spin resonance spin-trapping investigation Abs: Although it is assumed from in vitro experiments that the hydroxyl radical (*OH) may be responsible for chromium(VI) toxicity/carcinogenicity, no electron spin resonance (ESR) evidence for the generation of *OH in vivo has been reported. In this study, we have employed an ESR spin-trapping technique with 5,5-dimethylpyrroline-N-oxide (DMPO), a selective *OH trap, to detect *OH in blood. The ESR spectrum of spin adduct observed in the blood of mice given 4.8 mmol Cr(VI)/kg body weight exhibited the 1:2:2:1 intensity pattern of a quartet with a hyperfine coupling constant A(N) = A(H) = 14.81 G and g-value = 2.0067. The concentration of the spin adduct detected in the blood was 7.37 microM. The adduct production was inhibited by the addition of specific *OH scavengers such as sodium benzoate and methional to the blood. The results indicate that the spin adduct is nitroxide produced by the reaction of *OH with DMPO. This is the first report of ESR evidence for the in vivo generation of *OH in mammals by Cr(VI)."
1509569,Mariño-Balsa et al. 2000,"Comparative toxicity of dissolved metals to early larval stages of Palaemon serratus, Maja squinado, and Homarus gammarus (Crustacea:Decapoda)","The acute lethal toxicities of mercury, copper, and cadmium to the first larval stage of the prawn (Palaemon serratus), spider crab (Maja squinado), and lobster (Homarus gammarus) were tested. Chromium was also tested with the prawn. Mortality was recorded after 48 h (for lobster) or 72 h (for other species) incubation at 18 degrees C, and the median lethal concentrations (LC(50) +/- 95% confidence intervals) per individual and per mass unit were calculated. The LC(50) values were, 74 microg Hg/L, 3,304 microg Cu/L, 1,686 microg Cd/L, 12,486 microg Cr/L for prawn; 72 microg Hg/L, 50 microg Cu/L, 158 microg Cd/L for spider crab; and 48 microg Hg/L, 46 microg Cu/L, 34 microg Cd/L for lobster. Therefore, larvae of spider crab and lobster were markedly more sensitive than prawn to heavy metals and thus more suitable to use in seawater quality bioassays. Of these two species, spider crab is recommended due to its abundance, easier maintenance, and higher fecundity. The mercury LC(50) values for different larval stages of P. serratus (zoea I, II, V, and VI) were obtained, and no ontogenetic change in sensitivity to the metal could be detected.","Comparative toxicity of dissolved metals to early larval stages of Palaemon serratus, Maja squinado, and Homarus gammarus (Crustacea:Decapoda) Abs: The acute lethal toxicities of mercury, copper, and cadmium to the first larval stage of the prawn (Palaemon serratus), spider crab (Maja squinado), and lobster (Homarus gammarus) were tested. Chromium was also tested with the prawn. Mortality was recorded after 48 h (for lobster) or 72 h (for other species) incubation at 18 degrees C, and the median lethal concentrations (LC(50) +/- 95% confidence intervals) per individual and per mass unit were calculated. The LC(50) values were, 74 microg Hg/L, 3,304 microg Cu/L, 1,686 microg Cd/L, 12,486 microg Cr/L for prawn; 72 microg Hg/L, 50 microg Cu/L, 158 microg Cd/L for spider crab; and 48 microg Hg/L, 46 microg Cu/L, 34 microg Cd/L for lobster. Therefore, larvae of spider crab and lobster were markedly more sensitive than prawn to heavy metals and thus more suitable to use in seawater quality bioassays. Of these two species, spider crab is recommended due to its abundance, easier maintenance, and higher fecundity. The mercury LC(50) values for different larval stages of P. serratus (zoea I, II, V, and VI) were obtained, and no ontogenetic change in sensitivity to the metal could be detected."
1509568,Krishna and  BS 2000,Thermodynamics of Chromium(VI) Anionic Species Sorption onto Surfactant-Modified Montmorillonite Clay,"Batch sorption experiments performed on Cr(VI) species sorption showed a significantly enhanced removal of inorganic hexavalent chromium anionic species from aqueous solution by montmorillonite clays modified with quaternary amine, hexadecyltrimethylammonium (HDTMA) bromide. Unmodified clay had no affinity for chromium(VI) species. The sorption of Cr(VI) species has been carried out as a function of pH, contact time, adsorbate concentration (4.14x10(-5) to 8.62x10(-3) M), and temperature (5-45 degrees C). The surfactant-modified clay surface was stable when exposed to extremes in pH. The optimum pH for maximum sorption of Cr(VI) species was found to be at pH 1 and was constant between pH 2 and pH 6. The sorption data obtained was well described by DKR and Langmuir sorption isotherms. Sorption energy (E) for (i) surfactant sorption by montmorillonite clay and (ii) sorption of chromium(VI) species by surfactant modified clay have been computed from the DKR equation. Sorption energy evaluated for the sorption of both surfactant and Cr(VI) species showed that an ion-exchange mechanism was operative. The mechanism of retention appears to be replacement of counterion of the surfactant by Cr(VI) anionic species. Adsorbent capacity for the sorption of Cr(VI) species has been evaluated from the Langmuir sorption isotherm data. Thermodynamic parameters (Delta H degrees, Delta S degrees and Delta G degrees ) for surfactant sorption on montmorillonite clay and Cr(VI) sorption by modified clay have been evaluated. The specific rate constant for sorption of Cr(VI) species on modified montmorillonite was rapid during the first 10 min and equilibrium was found to be attained within 30 min. The sorption of Cr(VI) species onto modified montmorillonite clay followed first-order rate kinetics. Copyright 2000 Academic Press.","Thermodynamics of Chromium(VI) Anionic Species Sorption onto Surfactant-Modified Montmorillonite Clay Abs: Batch sorption experiments performed on Cr(VI) species sorption showed a significantly enhanced removal of inorganic hexavalent chromium anionic species from aqueous solution by montmorillonite clays modified with quaternary amine, hexadecyltrimethylammonium (HDTMA) bromide. Unmodified clay had no affinity for chromium(VI) species. The sorption of Cr(VI) species has been carried out as a function of pH, contact time, adsorbate concentration (4.14x10(-5) to 8.62x10(-3) M), and temperature (5-45 degrees C). The surfactant-modified clay surface was stable when exposed to extremes in pH. The optimum pH for maximum sorption of Cr(VI) species was found to be at pH 1 and was constant between pH 2 and pH 6. The sorption data obtained was well described by DKR and Langmuir sorption isotherms. Sorption energy (E) for (i) surfactant sorption by montmorillonite clay and (ii) sorption of chromium(VI) species by surfactant modified clay have been computed from the DKR equation. Sorption energy evaluated for the sorption of both surfactant and Cr(VI) species showed that an ion-exchange mechanism was operative. The mechanism of retention appears to be replacement of counterion of the surfactant by Cr(VI) anionic species. Adsorbent capacity for the sorption of Cr(VI) species has been evaluated from the Langmuir sorption isotherm data. Thermodynamic parameters (Delta H degrees, Delta S degrees and Delta G degrees ) for surfactant sorption on montmorillonite clay and Cr(VI) sorption by modified clay have been evaluated. The specific rate constant for sorption of Cr(VI) species on modified montmorillonite was rapid during the first 10 min and equilibrium was found to be attained within 30 min. The sorption of Cr(VI) species onto modified montmorillonite clay followed first-order rate kinetics. Copyright 2000 Academic Press."
1509567,Vanatta and  Coleman 2000,Ion-chromatographic assay of chromium(VI)-containing semiconductor etchants statistical comparison of two columns,"Semiconductor etchants are concentrated-acid mixtures that are prepared under tight specifications. Assay procedures are needed to ensure that the proportion of each component is within a small percentage (usually 10 relative percent or less) of the target concentration. One such etchant class contains chromium trioxide, usually in combination with HF and HNO3, While several ion-chromatographic columns can be used to analyze most mineral acids, chromium(VI) presents a problem. This latter species is highly retained by many separators and may also degrade the resins. This paper compares two columns that showed potential for success with these assays: the AS 11 and the AS16 separators (both from Dionex). These columns permit elution of chromium(VI) as chromate in 25 min or less. A representative mixture of HF, HNO3 and CrO3 was used in the research. Simultaneous calibration studies were conducted and the data sets analyzed statistically. Also investigated was the effect on the columns of repeated exposure to chromate.","Ion-chromatographic assay of chromium(VI)-containing semiconductor etchants statistical comparison of two columns Abs: Semiconductor etchants are concentrated-acid mixtures that are prepared under tight specifications. Assay procedures are needed to ensure that the proportion of each component is within a small percentage (usually 10 relative percent or less) of the target concentration. One such etchant class contains chromium trioxide, usually in combination with HF and HNO3, While several ion-chromatographic columns can be used to analyze most mineral acids, chromium(VI) presents a problem. This latter species is highly retained by many separators and may also degrade the resins. This paper compares two columns that showed potential for success with these assays: the AS 11 and the AS16 separators (both from Dionex). These columns permit elution of chromium(VI) as chromate in 25 min or less. A representative mixture of HF, HNO3 and CrO3 was used in the research. Simultaneous calibration studies were conducted and the data sets analyzed statistically. Also investigated was the effect on the columns of repeated exposure to chromate."
1509566,Vajpayee et al. 2000,"Chromium (VI) accumulation reduces chlorophyll biosynthesis, nitrate reductase activity and protein content in Nymphaea alba L","Plants of Nymphaea alba L. grown at various levels of chromium (VI) ranging from 1 to 200 microM accumulated chromium in concentration and duration-dependent manner. At all Cr levels, chromium accumulation by various plant tissues followed the order roots &gt; leaves &gt; rhizomes. Approximately 93% of total chromium present in the medium was accumulated by plants at lowest conentration (1 microM) used in the experiment. Chromium-induced toxicity appears at 1 microM chromium resulting in the build-up of delta-aminolevulinic acid (ALA) and reduced activities of delta-aminolevulinic acid dehydratase (ALAD) and nitrate reductase (NR), total chlorophyll (Chl) and protein contents. Ch1a was more sensitive than Ch1b to chromium toxicity. It could be inferred that chromium toxicity is not located at the level of ALA synthesis, but, probably at the ALAD activity which was more severely affected during chlorophyll biosynthesis. Finally, impaired chlorophyll biosynthesis resulted in reduced total chlorophyll content.","Chromium (VI) accumulation reduces chlorophyll biosynthesis, nitrate reductase activity and protein content in Nymphaea alba L Abs: Plants of Nymphaea alba L. grown at various levels of chromium (VI) ranging from 1 to 200 microM accumulated chromium in concentration and duration-dependent manner. At all Cr levels, chromium accumulation by various plant tissues followed the order roots &gt; leaves &gt; rhizomes. Approximately 93% of total chromium present in the medium was accumulated by plants at lowest conentration (1 microM) used in the experiment. Chromium-induced toxicity appears at 1 microM chromium resulting in the build-up of delta-aminolevulinic acid (ALA) and reduced activities of delta-aminolevulinic acid dehydratase (ALAD) and nitrate reductase (NR), total chlorophyll (Chl) and protein contents. Ch1a was more sensitive than Ch1b to chromium toxicity. It could be inferred that chromium toxicity is not located at the level of ALA synthesis, but, probably at the ALAD activity which was more severely affected during chlorophyll biosynthesis. Finally, impaired chlorophyll biosynthesis resulted in reduced total chlorophyll content."
1509565,Paul et al. 2000,Effects of pyridinium chlorochromate adulterant (urine luck) on testing for drugs of abuse and a method for quantitative detection of chromium (VI) in urine,"Pyridinium chlorochromate (PCC) as an adulterant is popular for concealing drug-positive results. When 11-nor-delta9-THC-9-carboxylic acid (THC-acid) in urine was treated with 2 mmol/L of PCC (Cr6+ 104 microg/mL), 58-100% of the THC-acid was lost. The loss increased with decreasing pH and increasing reaction time (0-3 days). Free codeine and free morphine remained unaffected by PCC at pH within the physiological range of the urine (pH 5-7). At lower pH, the loss of free morphine varied from 0 to 100%. Amphetamine, methamphetamine, benzoylecgonine, and PCP remained unaffected by PCC when exposed to the oxidant for three days in urine pH of 3-7. Chromium (VI) from PCC in a urine solution was detected by a color reaction with 1,5-diphenylcarbazide (DPC). When the reagent was added to the urine, an immediate red-violet color appeared. The chromium-DPC complex showed a characteristic absorption peak at wavelength 544 nm with a shoulder at wavelength 575 nm. The ratio of absorption was used to identify the chromium compound. The concentration of chromium (VI) was determined by measuring absorption at wavelength 544 nm and was linear over 0.5-20 microg/mL. The limit of detection of the procedure was 0.37 microg/mL.","Effects of pyridinium chlorochromate adulterant (urine luck) on testing for drugs of abuse and a method for quantitative detection of chromium (VI) in urine Abs: Pyridinium chlorochromate (PCC) as an adulterant is popular for concealing drug-positive results. When 11-nor-delta9-THC-9-carboxylic acid (THC-acid) in urine was treated with 2 mmol/L of PCC (Cr6+ 104 microg/mL), 58-100% of the THC-acid was lost. The loss increased with decreasing pH and increasing reaction time (0-3 days). Free codeine and free morphine remained unaffected by PCC at pH within the physiological range of the urine (pH 5-7). At lower pH, the loss of free morphine varied from 0 to 100%. Amphetamine, methamphetamine, benzoylecgonine, and PCP remained unaffected by PCC when exposed to the oxidant for three days in urine pH of 3-7. Chromium (VI) from PCC in a urine solution was detected by a color reaction with 1,5-diphenylcarbazide (DPC). When the reagent was added to the urine, an immediate red-violet color appeared. The chromium-DPC complex showed a characteristic absorption peak at wavelength 544 nm with a shoulder at wavelength 575 nm. The ratio of absorption was used to identify the chromium compound. The concentration of chromium (VI) was determined by measuring absorption at wavelength 544 nm and was linear over 0.5-20 microg/mL. The limit of detection of the procedure was 0.37 microg/mL."
1509563,Basavaiah et al. 2000,Quantitation of pharmaceutically important phenothiazines by oxidimetry,"A new spectrophotometric method for the assay of phenothiazines in pure form as well as in pharmaceutical formulations with the chromium(VI)-metol-sulfanilic acid system has been developed. The method is based on the oxidation of the drugs by a known excess of chromium(VI) and subsequent determination of the unreacted oxidant by interacting with metol and sulfanilic acid. The reacted oxidant corresponds to the drug content. The coloured species exhibits maximum absorbance at 530 nm. Beer's law is obeyed over the concentration range 5-60 micrograms ml-1 and the relative standard deviation is found to be less than 2%. The apparent molar absorptivities are in the range 3.77 x 10(3)-3.98 x 10(3) l mol-1 cm-1, the detection limits being in the range 0.6133-1.1349 micrograms ml-1. The method was successfully applied to the determination of the studied drugs in their formulations and the mean percentage recoveries were found to be 97.32-102.80%.","Quantitation of pharmaceutically important phenothiazines by oxidimetry Abs: A new spectrophotometric method for the assay of phenothiazines in pure form as well as in pharmaceutical formulations with the chromium(VI)-metol-sulfanilic acid system has been developed. The method is based on the oxidation of the drugs by a known excess of chromium(VI) and subsequent determination of the unreacted oxidant by interacting with metol and sulfanilic acid. The reacted oxidant corresponds to the drug content. The coloured species exhibits maximum absorbance at 530 nm. Beer's law is obeyed over the concentration range 5-60 micrograms ml-1 and the relative standard deviation is found to be less than 2%. The apparent molar absorptivities are in the range 3.77 x 10(3)-3.98 x 10(3) l mol-1 cm-1, the detection limits being in the range 0.6133-1.1349 micrograms ml-1. The method was successfully applied to the determination of the studied drugs in their formulations and the mean percentage recoveries were found to be 97.32-102.80%."
1509562,Myers et al. 2000,Chromium(VI) reductase activity is associated with the cytoplasmic membrane of anaerobically grown Shewanella putrefaciens MR-1,"Shewanella putrefaciens MR-1 can reduce a diverse array of compounds under anaerobic conditions, including manganese and iron oxides, fumarate, nitrate, and many other compounds. These reductive processes are apparently linked to a complex electron transport system. Chromium (Cr) is a toxic and mutagenic metal and bacteria could potentially be utilized to immobilize Cr by reducing the soluble and bioavailable state, Cr(VI), to the insoluble and less bioavailable state, Cr(III). Formate-dependent Cr(VI) reductase activity was detected in anaerobically grown cells of S. putrefaciens MR-1, with highest specific activity in the cytoplasmic membrane. Both formate and NADH served as electron donors for Cr(VI) reductase, whereas L-lactate or NADPH did not support any activity. The addition of 10 micromol l(-1) FMN markedly stimulated formate-dependent Cr(VI) reductase, and the activity was almost completely inhibited by diphenyliodonium chloride, an inhibitor of flavoproteins. Cr(VI) reductase activity was also inhibited by p-chloromercuriphenylsulphonate, azide, 2-heptyl-4-hydroxyquinolone-N-oxide, and antimycin A, suggesting involvement of a multi-component electron transport chain which could include cytochromes and quinones. Cr(V) was detected by electron paramagnetic resonance (EPR) spectroscopy, suggesting a one-electron reduction as the first step.","Chromium(VI) reductase activity is associated with the cytoplasmic membrane of anaerobically grown Shewanella putrefaciens MR-1 Abs: Shewanella putrefaciens MR-1 can reduce a diverse array of compounds under anaerobic conditions, including manganese and iron oxides, fumarate, nitrate, and many other compounds. These reductive processes are apparently linked to a complex electron transport system. Chromium (Cr) is a toxic and mutagenic metal and bacteria could potentially be utilized to immobilize Cr by reducing the soluble and bioavailable state, Cr(VI), to the insoluble and less bioavailable state, Cr(III). Formate-dependent Cr(VI) reductase activity was detected in anaerobically grown cells of S. putrefaciens MR-1, with highest specific activity in the cytoplasmic membrane. Both formate and NADH served as electron donors for Cr(VI) reductase, whereas L-lactate or NADPH did not support any activity. The addition of 10 micromol l(-1) FMN markedly stimulated formate-dependent Cr(VI) reductase, and the activity was almost completely inhibited by diphenyliodonium chloride, an inhibitor of flavoproteins. Cr(VI) reductase activity was also inhibited by p-chloromercuriphenylsulphonate, azide, 2-heptyl-4-hydroxyquinolone-N-oxide, and antimycin A, suggesting involvement of a multi-component electron transport chain which could include cytochromes and quinones. Cr(V) was detected by electron paramagnetic resonance (EPR) spectroscopy, suggesting a one-electron reduction as the first step."
1509561,Signorella et al. 2000,The reduction of CrVI to CrIII by the alpha and beta anomers of D-glucose in dimethyl sulfoxide. A comparative kinetic and mechanistic study,"The reduction of CrVI by alpha-D-glucose and beta-D-glucose was studied in dimethyl sulfoxide in the presence of pyridinium p-toluensulfonate, a medium where mutarotation is slower than the redox reaction. The two anomers reduce CrVI by formation of an intermediate CrVI ester precursor of the slow redox step. The equilibrium constant for the formation of the intermediate chromic ester and the rate of the redox steps are different for each anomer. alpha-D-Glucose forms the CrVI-Glc ester with a higher equilibrium constant than beta-D-glucose, but the electron transfer within this complex is slower than for the beta anomer. The difference is attributed to the better chelating ability of the 1,2-cis-diolate moiety of the alpha anomer. The CrV species, generated in the reaction mixture, reacts with the two anomers at a rate comparable with that of CrVI. The EPR spectra show that the alpha anomer forms several linkage isomers of the five-coordinate CrV bis-chelate, while beta-D-glucose affords a mixture of six-coordinate CrV monochelate and five-coordinate CrV bis-chelate. The conversion of the CrV mono- to bis-chelate is discussed in terms of the ability of the 1,2-cis- versus 1,2-trans-diolate moieties of the glucose anomers to bind CrV.","The reduction of CrVI to CrIII by the alpha and beta anomers of D-glucose in dimethyl sulfoxide. A comparative kinetic and mechanistic study Abs: The reduction of CrVI by alpha-D-glucose and beta-D-glucose was studied in dimethyl sulfoxide in the presence of pyridinium p-toluensulfonate, a medium where mutarotation is slower than the redox reaction. The two anomers reduce CrVI by formation of an intermediate CrVI ester precursor of the slow redox step. The equilibrium constant for the formation of the intermediate chromic ester and the rate of the redox steps are different for each anomer. alpha-D-Glucose forms the CrVI-Glc ester with a higher equilibrium constant than beta-D-glucose, but the electron transfer within this complex is slower than for the beta anomer. The difference is attributed to the better chelating ability of the 1,2-cis-diolate moiety of the alpha anomer. The CrV species, generated in the reaction mixture, reacts with the two anomers at a rate comparable with that of CrVI. The EPR spectra show that the alpha anomer forms several linkage isomers of the five-coordinate CrV bis-chelate, while beta-D-glucose affords a mixture of six-coordinate CrV monochelate and five-coordinate CrV bis-chelate. The conversion of the CrV mono- to bis-chelate is discussed in terms of the ability of the 1,2-cis- versus 1,2-trans-diolate moieties of the glucose anomers to bind CrV."
1509560,Soares et al. 2000,Selective determination of chromium (VI) in powdered milk infant formulas by electrothermal atomization atomic absorption spectrometry after ion exchange,"A previously developed method was adapted to the selective determination of hexavalent chromium in powdered milk infant formulas. The species in reconstituted milk was separated on an ion-exchange column, Chromabond NH2, and measured by electrothermal atomization atomic absorption spectrometry. The detection limit was 1.8 micrograms/L, and the linearity range under optimized conditions was 1.8-50.0 micrograms/L. The precision values were 4.1 and 6.5% for the analytical and overall procedures, respectively. The procedure was validated by the method of standard additions (5.0, 10.0, and 25.0 micrograms/L), and the recoveries were all &gt; 93%. The developed method is sensitive, accurate, and precise for determination of Cr(VI) in powdered milks. It was applied to the determination of Cr(VI) in 20 commercial brands, i.e., 7 infant formulas, 5 follow-up milks, and 8 dietetic milks. The values found ranged from &lt; 10 to 75 ng/g.","Selective determination of chromium (VI) in powdered milk infant formulas by electrothermal atomization atomic absorption spectrometry after ion exchange Abs: A previously developed method was adapted to the selective determination of hexavalent chromium in powdered milk infant formulas. The species in reconstituted milk was separated on an ion-exchange column, Chromabond NH2, and measured by electrothermal atomization atomic absorption spectrometry. The detection limit was 1.8 micrograms/L, and the linearity range under optimized conditions was 1.8-50.0 micrograms/L. The precision values were 4.1 and 6.5% for the analytical and overall procedures, respectively. The procedure was validated by the method of standard additions (5.0, 10.0, and 25.0 micrograms/L), and the recoveries were all &gt; 93%. The developed method is sensitive, accurate, and precise for determination of Cr(VI) in powdered milks. It was applied to the determination of Cr(VI) in 20 commercial brands, i.e., 7 infant formulas, 5 follow-up milks, and 8 dietetic milks. The values found ranged from &lt; 10 to 75 ng/g."
1509559,Susi et al. 2000,The use of a task-based exposure assessment model (T-BEAM) for assessment of metal fume exposures during welding and thermal cutting,"Elevated disease rates have been documented among construction workers for cancer, pneumonoconiosis, asbestosis, and silicosis. However, methodologies for exposure assessment in construction are not well described in the U.S. literature. Working through a cooperative agreement with the National Institute for Occupational Safety and Health (NIOSH), the Center to Protect Workers' Rights--a research arm of the Building and Construction Trades Department, AFL-CIO--has developed and used a &quot;Task-Based Exposure Assessment Model (T-BEAM)&quot; for construction. The characteristic elements of T-BEAM are: (1) an emphasis on the identification, implementation, and evaluation of engineering and work practice controls; and (2) use of experienced, specially trained construction workers (construction safety and health specialists) in the exposure assessment process. A task-based approach was used because tasks, or specialized skills, form the single greatest thread of continuity in the dynamic environment of construction. Workers in the construction industry come from several crafts and are typically employed by a large number of contractors throughout their career. Project types (e.g., residential or industrial rehabilitation) are also highly variable and present unique health risks. Finally, because construction involves building, renovating, or dismantling physical surroundings, the work site is constantly changing. Between 1995 and 1996, T-BEAM was applied to the collection of approximately 200 personal exposure measurements associated with &quot;hot work tasks&quot;--welding and thermal cutting. Data were collected with the assistance of specially trained, journeyman ironworkers, pipe fitters, and boilermakers on nine construction sites located throughout the United States. Portable local exhaust ventilation was provided to participating contractors with the intent of measuring its impact on exposure. Results indicate that data collected in a standardized, systematic fashion from multiple work sites can be used to characterize exposures among sampled trades. Comparison of results to American Conference of Governmental Industrial Hygienists (ACGIH) threshold limit values (TLVs) demonstrate a significant health hazard among sampled trades posed by welding and thermal cutting fume, manganese, nickel, and chromium VI. Direct estimates of the probability of exceeding the ACGIH TLV for respirable particulate suggests that boilermakers (100%) and ironworkers (71%) are at greatest risk. Other task variables evaluated with respect to exposure include task, whether work was performed indoors or outdoors, intermittency of work, and use of ventilation. Use of local or mechanical ventilation reduced mean exposures to fumes significantly.","The use of a task-based exposure assessment model (T-BEAM) for assessment of metal fume exposures during welding and thermal cutting Abs: Elevated disease rates have been documented among construction workers for cancer, pneumonoconiosis, asbestosis, and silicosis. However, methodologies for exposure assessment in construction are not well described in the U.S. literature. Working through a cooperative agreement with the National Institute for Occupational Safety and Health (NIOSH), the Center to Protect Workers' Rights--a research arm of the Building and Construction Trades Department, AFL-CIO--has developed and used a &quot;Task-Based Exposure Assessment Model (T-BEAM)&quot; for construction. The characteristic elements of T-BEAM are: (1) an emphasis on the identification, implementation, and evaluation of engineering and work practice controls; and (2) use of experienced, specially trained construction workers (construction safety and health specialists) in the exposure assessment process. A task-based approach was used because tasks, or specialized skills, form the single greatest thread of continuity in the dynamic environment of construction. Workers in the construction industry come from several crafts and are typically employed by a large number of contractors throughout their career. Project types (e.g., residential or industrial rehabilitation) are also highly variable and present unique health risks. Finally, because construction involves building, renovating, or dismantling physical surroundings, the work site is constantly changing. Between 1995 and 1996, T-BEAM was applied to the collection of approximately 200 personal exposure measurements associated with &quot;hot work tasks&quot;--welding and thermal cutting. Data were collected with the assistance of specially trained, journeyman ironworkers, pipe fitters, and boilermakers on nine construction sites located throughout the United States. Portable local exhaust ventilation was provided to participating contractors with the intent of measuring its impact on exposure. Results indicate that data collected in a standardized, systematic fashion from multiple work sites can be used to characterize exposures among sampled trades. Comparison of results to American Conference of Governmental Industrial Hygienists (ACGIH) threshold limit values (TLVs) demonstrate a significant health hazard among sampled trades posed by welding and thermal cutting fume, manganese, nickel, and chromium VI. Direct estimates of the probability of exceeding the ACGIH TLV for respirable particulate suggests that boilermakers (100%) and ironworkers (71%) are at greatest risk. Other task variables evaluated with respect to exposure include task, whether work was performed indoors or outdoors, intermittency of work, and use of ventilation. Use of local or mechanical ventilation reduced mean exposures to fumes significantly."
1509558,Shettlemore and  Bundy 1999,Toxicity measurement of orthopedic implant alloy degradation products using a bioluminescent bacterial assay,"The toxicity of aqueous metal solutions representative of ionic degradation products from orthopedic implant alloys was determined using a bacterial bioluminescence assay, Microtox. The toxicity of forms of the individual elements released from ASTM F75 Co-Cr-Mo (Co-Cr-Mo), F138 316L stainless steel (316L), and F136 Ti-6Al-4V (Ti-6Al-4V) was first determined, and a mathematical model was developed to predict the toxicity of mixtures of these ions. Aqueous metal solutions were then mixed according to the proportions of the ions found in these alloys, and their toxicity was measured with Microtox. Mixture behavior was classified as synergistic, antagonistic, or additive by comparing measured toxicity to predicted toxicity. Since relating these tests to actual implant corrosion processes can be confounded by selective leaching, the predicted and measured toxicity of aqueous metal solutions mixed according to proportions representative of selective leaching were next determined, and the mixture behaviors were classified as before. The most toxic individual alloying elements were found to be hexavalent Cr, Ni, and Co, in that order: a finding in accord with prior biocompatibility research. Co-Cr-Mo was found to be the most toxic alloy mixture of both those combined according to alloy composition and those combined to reflect selective leaching. The Ti-6Al-4V mixtures were found to behave synergistically, while the Co-Cr-Mo and 316L mixtures behaved antagonistically. By providing insight into degradation product toxicity and elemental interaction, these experiments demonstrate the utility of employing bioluminescent bacterial assays to investigate biocompatibility of implant materials. Further studies to more closely simulate in vivo conditions, though, are required to fully gauge their potential in this regard.","Toxicity measurement of orthopedic implant alloy degradation products using a bioluminescent bacterial assay Abs: The toxicity of aqueous metal solutions representative of ionic degradation products from orthopedic implant alloys was determined using a bacterial bioluminescence assay, Microtox. The toxicity of forms of the individual elements released from ASTM F75 Co-Cr-Mo (Co-Cr-Mo), F138 316L stainless steel (316L), and F136 Ti-6Al-4V (Ti-6Al-4V) was first determined, and a mathematical model was developed to predict the toxicity of mixtures of these ions. Aqueous metal solutions were then mixed according to the proportions of the ions found in these alloys, and their toxicity was measured with Microtox. Mixture behavior was classified as synergistic, antagonistic, or additive by comparing measured toxicity to predicted toxicity. Since relating these tests to actual implant corrosion processes can be confounded by selective leaching, the predicted and measured toxicity of aqueous metal solutions mixed according to proportions representative of selective leaching were next determined, and the mixture behaviors were classified as before. The most toxic individual alloying elements were found to be hexavalent Cr, Ni, and Co, in that order: a finding in accord with prior biocompatibility research. Co-Cr-Mo was found to be the most toxic alloy mixture of both those combined according to alloy composition and those combined to reflect selective leaching. The Ti-6Al-4V mixtures were found to behave synergistically, while the Co-Cr-Mo and 316L mixtures behaved antagonistically. By providing insight into degradation product toxicity and elemental interaction, these experiments demonstrate the utility of employing bioluminescent bacterial assays to investigate biocompatibility of implant materials. Further studies to more closely simulate in vivo conditions, though, are required to fully gauge their potential in this regard."
1509557,Go?ebiewski et al. 1999,Synthesis and biological activity of new diarylalkenes,"Condensation of 5-nitro, 3-chloro-, and 5-chlorosalicylic acid with formaldehyde afforded dimeric disalicylmethanes which were O-methylated with dimethyl sulfate and oxidized with chromium(VI) oxide to give the diarylketones 10, 11, 12. Wittig reaction with ylides obtained by deprotonation of alkyltriphenylphosphonium salts with sodium bis (trimethylsilyl)amide yielded a series of diarylalkenes. Some of the obtained compounds showed high antimicrobial activity in vitro against Bacillus subtilis and Mycobacterium smegmatis.","Synthesis and biological activity of new diarylalkenes Abs: Condensation of 5-nitro, 3-chloro-, and 5-chlorosalicylic acid with formaldehyde afforded dimeric disalicylmethanes which were O-methylated with dimethyl sulfate and oxidized with chromium(VI) oxide to give the diarylketones 10, 11, 12. Wittig reaction with ylides obtained by deprotonation of alkyltriphenylphosphonium salts with sodium bis (trimethylsilyl)amide yielded a series of diarylalkenes. Some of the obtained compounds showed high antimicrobial activity in vitro against Bacillus subtilis and Mycobacterium smegmatis."
1509556,Alfaya 1999,The Preparation and Application of Silica-Zirconia Xerogel as Potentiometric Sensor for Chromium(VI),"Xerogel of SiO2/ZrO2 with Zr in amounts of 17.4, 25.4, and 32.8 wt% were prepared by the sol-gel processing method. The oxide particles were homogeneously distributed in the xerogel and the Cr(VI) adsorption capacities were 5.2, 7.0, and 7.8 wt%, following the increasing order of the ZrO2 loading. The potentiometric response was better for samples with higher ZrO2 loading, and the plot of E vs -log aCr(VI), where a is the activity, showed a linear correlation with an angular coefficent of 57.2 mV, very close to the 59 mV required for nernstian behavior. For the other two samples with lower metal oxide loadings, the angular coefficients were lower, showing a larger deviation from ideal behavior. The potentiometric selectivity constants, Kpotx,y, where x is the primary ion (Cr(VI) in the present case) and y is the interferent ion, were calculated. The following values of Kpotx,y were found for the different interferent ions: Cl-, 0.24; NO-3, 2 x 10(-3); HPO2-4, 2 x 10(-4); SO2-4, 3 x 10(-5); Cr3+, 6 x 10(-9). Copyright 1999 Academic Press.","The Preparation and Application of Silica-Zirconia Xerogel as Potentiometric Sensor for Chromium(VI) Abs: Xerogel of SiO2/ZrO2 with Zr in amounts of 17.4, 25.4, and 32.8 wt% were prepared by the sol-gel processing method. The oxide particles were homogeneously distributed in the xerogel and the Cr(VI) adsorption capacities were 5.2, 7.0, and 7.8 wt%, following the increasing order of the ZrO2 loading. The potentiometric response was better for samples with higher ZrO2 loading, and the plot of E vs -log aCr(VI), where a is the activity, showed a linear correlation with an angular coefficent of 57.2 mV, very close to the 59 mV required for nernstian behavior. For the other two samples with lower metal oxide loadings, the angular coefficients were lower, showing a larger deviation from ideal behavior. The potentiometric selectivity constants, Kpotx,y, where x is the primary ion (Cr(VI) in the present case) and y is the interferent ion, were calculated. The following values of Kpotx,y were found for the different interferent ions: Cl-, 0.24; NO-3, 2 x 10(-3); HPO2-4, 2 x 10(-4); SO2-4, 3 x 10(-5); Cr3+, 6 x 10(-9). Copyright 1999 Academic Press."
1509555,Higgins and  Dobbins 1998,In situ reduction of hexavalent chromium in alkaline soils enriched with chromite ore processing residue,"In investigating chromium sites in New Jersey, it has been observed that an organic-rich 0.5- to 4-foot-thick layer of decayed vegetation (locally known as &quot;meadowmat&quot;) underlying the chromium-containing material acts as a natural barrier to the migration of Cr(VI). The groundwater in a sand layer directly beneath the meadowmat has been shown to contain low or nondetectable levels of chromium. The meadowmat is under highly reduced conditions due to bacterial activity associated with the organic material. Based on the observed ability of the meadowmat to reduce Cr(VI) to Cr(III), the feasibility of in situ reduction of Cr(VI) to Cr(III) at chromite ore processing residue (COPR) sites was investigated in biologically-active, laboratory-scale test columns. COPR typically has a high pH (in excess of 12) and may contain total chromium concentrations as high as 70,000 mg/kg. Experimental results demonstrated that the addition of a mineral acid (to lower the pH to between 7.0 and 9.5) and a bacteria-rich organic substrate (fresh manure) resulted in the reduction of Cr(VI) to the less toxic and less mobile trivalent form. Pore water Cr(VI) was reduced from approximately 800 mg/L to less than 0.05 mg/L over a period of eight months. This is less than the U.S. Environmental Protection Agency's (EPA) Maximum Contaminant Level (MCL) for chromium in drinking water of 0.1 mg/L. Solid phase Cr(VI) concentrations decreased from approximately 2,000 mg/kg to less than 10 mg/kg in the columns over a period of 11 months while the total chromium concentrations remained unchanged. Toxicity Characteristic Leaching Procedure (TCLP) extract from the treated columns met the regulatory limit of 5 mg/L of Cr, whereas the untreated samples had TCLP extract concentrations greater than 40 mg/L. This study demonstrated the potential applicability of in situ reduction to soils contaminated with Cr(VI) by adjusting the pH to between 7.0 and 9.5 and mixing in a bacteria-rich organic substrate.","In situ reduction of hexavalent chromium in alkaline soils enriched with chromite ore processing residue Abs: In investigating chromium sites in New Jersey, it has been observed that an organic-rich 0.5- to 4-foot-thick layer of decayed vegetation (locally known as &quot;meadowmat&quot;) underlying the chromium-containing material acts as a natural barrier to the migration of Cr(VI). The groundwater in a sand layer directly beneath the meadowmat has been shown to contain low or nondetectable levels of chromium. The meadowmat is under highly reduced conditions due to bacterial activity associated with the organic material. Based on the observed ability of the meadowmat to reduce Cr(VI) to Cr(III), the feasibility of in situ reduction of Cr(VI) to Cr(III) at chromite ore processing residue (COPR) sites was investigated in biologically-active, laboratory-scale test columns. COPR typically has a high pH (in excess of 12) and may contain total chromium concentrations as high as 70,000 mg/kg. Experimental results demonstrated that the addition of a mineral acid (to lower the pH to between 7.0 and 9.5) and a bacteria-rich organic substrate (fresh manure) resulted in the reduction of Cr(VI) to the less toxic and less mobile trivalent form. Pore water Cr(VI) was reduced from approximately 800 mg/L to less than 0.05 mg/L over a period of eight months. This is less than the U.S. Environmental Protection Agency's (EPA) Maximum Contaminant Level (MCL) for chromium in drinking water of 0.1 mg/L. Solid phase Cr(VI) concentrations decreased from approximately 2,000 mg/kg to less than 10 mg/kg in the columns over a period of 11 months while the total chromium concentrations remained unchanged. Toxicity Characteristic Leaching Procedure (TCLP) extract from the treated columns met the regulatory limit of 5 mg/L of Cr, whereas the untreated samples had TCLP extract concentrations greater than 40 mg/L. This study demonstrated the potential applicability of in situ reduction to soils contaminated with Cr(VI) by adjusting the pH to between 7.0 and 9.5 and mixing in a bacteria-rich organic substrate."
1509554,Rodriguez-Pinero et al. 1998,Stabilization of a chromium-containing solid waste: immobilization of hexavalent chromium,"This article describes the stabilization/solidification (S/S) of a steel industry waste, using a common type-F fly ash from a coal power station as the main binder. The waste, which contains hazardous levels of metals, may be stabilized by a conventional S/S to achieve permissible Pb, Cd, and Zn concentrations in the Toxicity Characteristic Leaching Procedure (TCLP) leachates of S/S solids. On the other hand, the stabilization of Cr(VI), also present in the waste, requires a reducing pretreatment stage with ferrous sulfate to attain TCLP leachates within limits. A bibliographic study on the stabilization of Cr(VI)-containing wastes is included in the paper, along with a discussion on the lowest Cr concentration in TCLP and aqueous (DIN) leachates.","Stabilization of a chromium-containing solid waste: immobilization of hexavalent chromium Abs: This article describes the stabilization/solidification (S/S) of a steel industry waste, using a common type-F fly ash from a coal power station as the main binder. The waste, which contains hazardous levels of metals, may be stabilized by a conventional S/S to achieve permissible Pb, Cd, and Zn concentrations in the Toxicity Characteristic Leaching Procedure (TCLP) leachates of S/S solids. On the other hand, the stabilization of Cr(VI), also present in the waste, requires a reducing pretreatment stage with ferrous sulfate to attain TCLP leachates within limits. A bibliographic study on the stabilization of Cr(VI)-containing wastes is included in the paper, along with a discussion on the lowest Cr concentration in TCLP and aqueous (DIN) leachates."
1509553,Ihnat et al. 1997,Suppression of P-glycoprotein expression and multidrug resistance by DNA cross-linking agents,"Overexpression of the trans-membrane drug efflux pump P-glycoprotein is one of the major mechanisms by which cancer cells develop multidrug resistance. We demonstrated previously that noncytotoxic doses of various genotoxic chemicals, particularly DNA cross-linking agents, preferentially altered expression of inducible genes. These effects occurred principally at the transcriptional level and were closely correlated temporally with DNA damage. Because the mdr1 gene coding for P-glycoprotein has been reported to be highly inducible, we were interested in the effects of genotoxic cancer chemotherapy agents on its expression. We report that the DNA cross-linking agent mitomycin C significantly suppressed mRNA and protein expression of P-glycoprotein and decreased the rate of drug efflux. Mitomycin C pretreatment also significantly increased the sensitivity of cancer cells to subsequent killing by the P-glycoprotein substrate doxorubicin, decreasing the ED50 by 5- to 10-fold. Suppression of P-glycoprotein expression was also observed with subtoxic doses of the DNA cross-linking agents cisplatin, BMS181174, and chromium(VI). These effects occurred in both human and rodent cell lines; in cell lines derived from colon, breast, leukemia, neuroblastoma, and hepatoma tumors; and under both monolayer and &quot;spheroid&quot; culture conditions. These results suggest the basis for novel clinical cancer chemotherapy regimens aimed at drug-resistant tumors, in which a sub-chemotherapeutic dose of a DNA cross-linking agent is used to modulate the multidrug resistance phenotype prior to treatment with a second cytotoxic agent.","Suppression of P-glycoprotein expression and multidrug resistance by DNA cross-linking agents Abs: Overexpression of the trans-membrane drug efflux pump P-glycoprotein is one of the major mechanisms by which cancer cells develop multidrug resistance. We demonstrated previously that noncytotoxic doses of various genotoxic chemicals, particularly DNA cross-linking agents, preferentially altered expression of inducible genes. These effects occurred principally at the transcriptional level and were closely correlated temporally with DNA damage. Because the mdr1 gene coding for P-glycoprotein has been reported to be highly inducible, we were interested in the effects of genotoxic cancer chemotherapy agents on its expression. We report that the DNA cross-linking agent mitomycin C significantly suppressed mRNA and protein expression of P-glycoprotein and decreased the rate of drug efflux. Mitomycin C pretreatment also significantly increased the sensitivity of cancer cells to subsequent killing by the P-glycoprotein substrate doxorubicin, decreasing the ED50 by 5- to 10-fold. Suppression of P-glycoprotein expression was also observed with subtoxic doses of the DNA cross-linking agents cisplatin, BMS181174, and chromium(VI). These effects occurred in both human and rodent cell lines; in cell lines derived from colon, breast, leukemia, neuroblastoma, and hepatoma tumors; and under both monolayer and &quot;spheroid&quot; culture conditions. These results suggest the basis for novel clinical cancer chemotherapy regimens aimed at drug-resistant tumors, in which a sub-chemotherapeutic dose of a DNA cross-linking agent is used to modulate the multidrug resistance phenotype prior to treatment with a second cytotoxic agent."
1509552,Nygren and  Wahlberg 1998,Speciation of chromium in tanned leather gloves and relapse of chromium allergy from tanned leather samples,"There are concerns that wearing chromium tanned leather gloves can provoke a lapse of hand dermatitis in chromium sensitive patients. Various forms of chromium have different biological effects and the determination of total chromium (both soluble and insoluble), which often is used in clinical studies, may therefore not be an adequate measure of the adverse exposure. However, investigations, where dissolution of hexavalent chromium from leather gloves has been experimentally studied, could not been found in the literature. The aim of this pilot study was therefore to determine the total amount of chromium and the amount of sweat leachable chromium in different leather glove materials and also to apply samples of these materials in a patch test to chromium sensitive patients to see if they could provoke a reaction. The results showed tha chromium tanned leather contained about 3% (m/m) chromium. Chromium can also be found in dyed vegetable tanned leather, probably emanating from the leather dye. Small amounts (average 0.08% m/m) of leachable hexavalent chromium were found in both chromium and vegetable tanned leathers. Thus, the risk of relapse of chromium dermatitis cannot be disregarded and further studies on the causes of relapse of chromium dermatitis are necessary.","Speciation of chromium in tanned leather gloves and relapse of chromium allergy from tanned leather samples Abs: There are concerns that wearing chromium tanned leather gloves can provoke a lapse of hand dermatitis in chromium sensitive patients. Various forms of chromium have different biological effects and the determination of total chromium (both soluble and insoluble), which often is used in clinical studies, may therefore not be an adequate measure of the adverse exposure. However, investigations, where dissolution of hexavalent chromium from leather gloves has been experimentally studied, could not been found in the literature. The aim of this pilot study was therefore to determine the total amount of chromium and the amount of sweat leachable chromium in different leather glove materials and also to apply samples of these materials in a patch test to chromium sensitive patients to see if they could provoke a reaction. The results showed tha chromium tanned leather contained about 3% (m/m) chromium. Chromium can also be found in dyed vegetable tanned leather, probably emanating from the leather dye. Small amounts (average 0.08% m/m) of leachable hexavalent chromium were found in both chromium and vegetable tanned leathers. Thus, the risk of relapse of chromium dermatitis cannot be disregarded and further studies on the causes of relapse of chromium dermatitis are necessary."
1509551,Accominotti et al. 1998,Contribution to chromium and nickel enrichment during cooking of foods in stainless steel utensils,"Nickel ingestion can cause exacerbation of dermatitis in patients who are already nickel-sensitive; Chromium (Cr VI) is the 2nd allergen, after nickel. However, stainless steel is widely used in home cookware. In this study, we determined nickel and chromium levels by atomic absorption spectrometry in 11 habitual menus cooked in different grades of stainless steel utensils. We noted a great difference in nickel and chromium intake depending on the menu, and a significant difference between the glass and stainless steel saucepans, but this was very low compared with the levels of nickel and chromium contained in the menus; mean intakes of these elements were under the tolerable daily intake (TDI) recommended by the World Health Organization. Hence, there is no advantage for nickel-sensitive patients in switching to materials other than stainless steel, provided that this is of good quality.","Contribution to chromium and nickel enrichment during cooking of foods in stainless steel utensils Abs: Nickel ingestion can cause exacerbation of dermatitis in patients who are already nickel-sensitive; Chromium (Cr VI) is the 2nd allergen, after nickel. However, stainless steel is widely used in home cookware. In this study, we determined nickel and chromium levels by atomic absorption spectrometry in 11 habitual menus cooked in different grades of stainless steel utensils. We noted a great difference in nickel and chromium intake depending on the menu, and a significant difference between the glass and stainless steel saucepans, but this was very low compared with the levels of nickel and chromium contained in the menus; mean intakes of these elements were under the tolerable daily intake (TDI) recommended by the World Health Organization. Hence, there is no advantage for nickel-sensitive patients in switching to materials other than stainless steel, provided that this is of good quality."
1509550,Padarauskas et al. 1998,"On-line preconcentration and determination of chromium(VI) in waters by high-performance liquid chromatography using precolumn complexation with 1,5-diphenylcarbazide","A method for on-line chromatographic preconcentration and determination of chromium(VI) traces has been developed. Chromate was preconcentrated on a C18 column (50 x 6 mm I.D.) after complexation with diphenylcarbazide (DPC). Following the preconcentration step, analysis of the sample was performed using a C18 column (100 x 6 mm I.D.) with an eluent containing 6.10(-3) mol/l sulphuric acid and 20% (v/v) acetonitrile. Direct spectrophotometric detection at 546 nm was used. Experimental parameters such as mobile phase pH, DPC concentration, preconcentration flow-rate, sample volume were optimized for preconcentration and detection of Cr(VI)-DPC complex. Under the optimum conditions, most metal ions [Cr(III), Fe(III), Cu(II), Hg(II), Mo(VI), V(V)] and inorganic anions did not interfere. A detection limit of 0.02 ng/ml Cr(VI) can be attained when a sample volume of 100 ml is used. The technique has been applied successfully to the determination of Cr(VI) traces in drinking, surface and groundwater samples and the recoveries of added chromium were in the range 94-104%.","On-line preconcentration and determination of chromium(VI) in waters by high-performance liquid chromatography using precolumn complexation with 1,5-diphenylcarbazide Abs: A method for on-line chromatographic preconcentration and determination of chromium(VI) traces has been developed. Chromate was preconcentrated on a C18 column (50 x 6 mm I.D.) after complexation with diphenylcarbazide (DPC). Following the preconcentration step, analysis of the sample was performed using a C18 column (100 x 6 mm I.D.) with an eluent containing 6.10(-3) mol/l sulphuric acid and 20% (v/v) acetonitrile. Direct spectrophotometric detection at 546 nm was used. Experimental parameters such as mobile phase pH, DPC concentration, preconcentration flow-rate, sample volume were optimized for preconcentration and detection of Cr(VI)-DPC complex. Under the optimum conditions, most metal ions [Cr(III), Fe(III), Cu(II), Hg(II), Mo(VI), V(V)] and inorganic anions did not interfere. A detection limit of 0.02 ng/ml Cr(VI) can be attained when a sample volume of 100 ml is used. The technique has been applied successfully to the determination of Cr(VI) traces in drinking, surface and groundwater samples and the recoveries of added chromium were in the range 94-104%."
1509549,Sugden and  Wetterhahn 1997,Direct and hydrogen peroxide-induced chromium(V) oxidation of deoxyribose in single-stranded and double-stranded calf thymus DNA,"Oxidative DNA damage by a model Cr(V) complex, [CrO(ehba)2]-, with and without added H2O2, was investigated for the formation of base and sugar products derived from C1', C4', and C5' hydrogen atom abstraction mechanisms. EPR studies with 5,5-dimethylpyrroline N-oxide (DMPO) have shown that Cr(V)-ehba alone can oxidize the spin trap via a direct chromium pathway, whereas reactions of Cr(V)-ehba in the presence of H2O2 generated the hydroxyl radical. Direct (or metal-centered) Cr(V)-ehba oxidation of single-stranded (ss) and double-stranded (ds) calf thymus DNA demonstrated the formation of thiobarbituric acid-reactive species (TBARS) and glycolic acid in an O2-dependent manner, consistent with abstraction of the C4' H atom. A minor C1' H atom abstraction mechanism was also observed for direct Cr(V) oxidation of DNA, but no C5' H atom abstraction product was observed. Direct Cr(V) oxidation of ss- and ds-DNA also caused the release of all four nucleic acid bases with a preference for the pyrimidines cytosine and thymine in ds-DNA, but no base release preference was observed in ss-DNA. This base release was O2-independent and could not be accounted for by the H atom abstraction mechanisms in this study. Reaction of Cr(V)-ehba with H2O2 and DNA yielded products consistent with all three DNA oxidation pathways measured, namely, C1', C4', and C5' H atom abstractions. Cr(V)-ehba and H2O2 also mediated a nonpreferential release of DNA bases with the exception of the oxidatively sensitive purine, guanine. Direct and H2O2-induced Cr(V) DNA oxidation had opposing substrate preferences, with direct Cr(V) oxidation favoring ss-DNA while H2O2-induced Cr(V) oxidative damage favored ds-DNA. These results may help explain the carcinogenic mechanism of chromium(VI) and serve to highlight the differences and similarities in DNA oxidation between high-valent chromium and oxygen-based radicals.","Direct and hydrogen peroxide-induced chromium(V) oxidation of deoxyribose in single-stranded and double-stranded calf thymus DNA Abs: Oxidative DNA damage by a model Cr(V) complex, [CrO(ehba)2]-, with and without added H2O2, was investigated for the formation of base and sugar products derived from C1', C4', and C5' hydrogen atom abstraction mechanisms. EPR studies with 5,5-dimethylpyrroline N-oxide (DMPO) have shown that Cr(V)-ehba alone can oxidize the spin trap via a direct chromium pathway, whereas reactions of Cr(V)-ehba in the presence of H2O2 generated the hydroxyl radical. Direct (or metal-centered) Cr(V)-ehba oxidation of single-stranded (ss) and double-stranded (ds) calf thymus DNA demonstrated the formation of thiobarbituric acid-reactive species (TBARS) and glycolic acid in an O2-dependent manner, consistent with abstraction of the C4' H atom. A minor C1' H atom abstraction mechanism was also observed for direct Cr(V) oxidation of DNA, but no C5' H atom abstraction product was observed. Direct Cr(V) oxidation of ss- and ds-DNA also caused the release of all four nucleic acid bases with a preference for the pyrimidines cytosine and thymine in ds-DNA, but no base release preference was observed in ss-DNA. This base release was O2-independent and could not be accounted for by the H atom abstraction mechanisms in this study. Reaction of Cr(V)-ehba with H2O2 and DNA yielded products consistent with all three DNA oxidation pathways measured, namely, C1', C4', and C5' H atom abstractions. Cr(V)-ehba and H2O2 also mediated a nonpreferential release of DNA bases with the exception of the oxidatively sensitive purine, guanine. Direct and H2O2-induced Cr(V) DNA oxidation had opposing substrate preferences, with direct Cr(V) oxidation favoring ss-DNA while H2O2-induced Cr(V) oxidative damage favored ds-DNA. These results may help explain the carcinogenic mechanism of chromium(VI) and serve to highlight the differences and similarities in DNA oxidation between high-valent chromium and oxygen-based radicals."
1509548,van Heerden et al. 1994,Death by tanning--a case of fatal basic chromium sulphate poisoning,"A woman ingested 400 ml of leather tanning solution containing 48 g of basic chromium sulphate (CrOHSO4). This substance forms hydrogen ions and trivalent chromium when it reacts with tissue proteins. The patient died of cardiogenic shock, complicated by pancreatitis and gut mucosal necrosis and haemorrhage. There are no reported cases of toxicity due to oral ingestion of trivalent chromium. Toxicity of hexavalent and trivalent chromium is discussed and suggestions made for management of future cases.","Death by tanning--a case of fatal basic chromium sulphate poisoning Abs: A woman ingested 400 ml of leather tanning solution containing 48 g of basic chromium sulphate (CrOHSO4). This substance forms hydrogen ions and trivalent chromium when it reacts with tissue proteins. The patient died of cardiogenic shock, complicated by pancreatitis and gut mucosal necrosis and haemorrhage. There are no reported cases of toxicity due to oral ingestion of trivalent chromium. Toxicity of hexavalent and trivalent chromium is discussed and suggestions made for management of future cases."
1509547,Stridsklev et al. 1993,Biologic monitoring of chromium and nickel among stainless steel welders using the manual mental arc method,"Forty manual metal arc welders welding stainless steel (SS) were monitored for 1-7 workdays measuring total chromium (Cr), water-soluble hexavalent CrVI, and nickel (Ni) in the working atmosphere, and Cr and Ni in blood and urine. The mean daily increase was 1.0 microgram Cr/l in plasma and 5.6 micrograms Cr/g creatinine in urine. There were significant correlations between total Cr and CrVI in air and the total Cr in biologic fluids. This was not the case for the corresponding correlations for Ni. The observed correlations between urinary and plasma Cr levels may permit interchange of these body fluids for biologic monitoring at high exposures. The results indicate that urine sampled after work is a body fluid versatile for routine monitoring of Cr in SS welders. Smokers had higher levels of Cr in biologic fluids than did nonsmokers at equivalent levels of air CrVI. The results also indicate that filter masks provide better protection against uptake of Cr in the airways than air-stream helmets.","Biologic monitoring of chromium and nickel among stainless steel welders using the manual mental arc method Abs: Forty manual metal arc welders welding stainless steel (SS) were monitored for 1-7 workdays measuring total chromium (Cr), water-soluble hexavalent CrVI, and nickel (Ni) in the working atmosphere, and Cr and Ni in blood and urine. The mean daily increase was 1.0 microgram Cr/l in plasma and 5.6 micrograms Cr/g creatinine in urine. There were significant correlations between total Cr and CrVI in air and the total Cr in biologic fluids. This was not the case for the corresponding correlations for Ni. The observed correlations between urinary and plasma Cr levels may permit interchange of these body fluids for biologic monitoring at high exposures. The results indicate that urine sampled after work is a body fluid versatile for routine monitoring of Cr in SS welders. Smokers had higher levels of Cr in biologic fluids than did nonsmokers at equivalent levels of air CrVI. The results also indicate that filter masks provide better protection against uptake of Cr in the airways than air-stream helmets."
1509546,Mccaffrey et al. 1994,Effects of the genotoxic carcinogen chromium(VI) on basal and hormone-inducible phosphoenolpyruvate carboxykinase gene expression in vivo: correlation with glucocorticoid- and developmentally regulated expression,"Previous studies have shown that a number of different genotoxic carcinogens that induce different types of DNA damage preferentially alter the expression of inducible genes in vivo. To investigate further the mechanistic basis for these effects, we examined the effects of the human lung carcinogen chromium(VI) on expression of the hormone-inducible cytosolic phosphoenolpyruvate carboxykinase (PEPCK) gene in chick embryo liver. Chromium(VI) pretreatment had significant effects on both basal and glucocorticoid-inducible PEPCK expression in 14-d-old embryo liver. These effects were principally a result of changes in PEPCK transcription. In contrast, treatment with chromium(VI) 1 h after treatment with glucocorticoid had no effect on PEPCK induction, suggesting that an early event in the induction process is the target for carcinogen effects. In 16-d-old liver, in which PEPCK expression is no longer responsive to glucocorticoid induction, both basal and inducible PEPCK expression were also refractory to chromium(VI) effects, indicating that carcinogen responsiveness is a phenotypic rather than an inherent property of inducible genes and is related to their competence for induction. Chromium(VI) had no effect on cAMP induction of PEPCK expression, demonstrating that carcinogens target their effects to specific regulatory pathways. Comparison of the effects of chromium(VI) with those of cycloheximide suggests that chromium(VI) targets its effects to a labile, constitutively expressed repressor involved in PEPCK gene regulation.","Effects of the genotoxic carcinogen chromium(VI) on basal and hormone-inducible phosphoenolpyruvate carboxykinase gene expression in vivo: correlation with glucocorticoid- and developmentally regulated expression Abs: Previous studies have shown that a number of different genotoxic carcinogens that induce different types of DNA damage preferentially alter the expression of inducible genes in vivo. To investigate further the mechanistic basis for these effects, we examined the effects of the human lung carcinogen chromium(VI) on expression of the hormone-inducible cytosolic phosphoenolpyruvate carboxykinase (PEPCK) gene in chick embryo liver. Chromium(VI) pretreatment had significant effects on both basal and glucocorticoid-inducible PEPCK expression in 14-d-old embryo liver. These effects were principally a result of changes in PEPCK transcription. In contrast, treatment with chromium(VI) 1 h after treatment with glucocorticoid had no effect on PEPCK induction, suggesting that an early event in the induction process is the target for carcinogen effects. In 16-d-old liver, in which PEPCK expression is no longer responsive to glucocorticoid induction, both basal and inducible PEPCK expression were also refractory to chromium(VI) effects, indicating that carcinogen responsiveness is a phenotypic rather than an inherent property of inducible genes and is related to their competence for induction. Chromium(VI) had no effect on cAMP induction of PEPCK expression, demonstrating that carcinogens target their effects to specific regulatory pathways. Comparison of the effects of chromium(VI) with those of cycloheximide suggests that chromium(VI) targets its effects to a labile, constitutively expressed repressor involved in PEPCK gene regulation."
1509545,Florence et al. 1994,Toxicity of nickel ores to marine organisms,"Queensland Nickel proposes to import New Caledonian (Ballande) and Indonesian (Gebe) nickel ores, one option being ship-to-barge transfer in Halifax Bay, North Queensland. Because small amounts of ore may be split during the unloading and transfer operations, it was important to investigate the potential impact of the spilt ore on the ecological health of the Bay. Long-term leaching of the ores with seawater showed that only nickel and chromium (VI) were released from the ores in sufficient concentrations to cause toxicity to a range of marine organisms. The soluble fractions of nickel and chromium (VI) were released from the ores within a few days. Nickel, chromium (VI) and the ore leachates showed similar toxicity to the juvenile banana prawn Penaeus merguiensis, the amphipod Allorchestes compressa and both temperature (22 degrees C) and tropical (27 degrees C) strains of the unicellular marine alga Nitzschia closterium. In a series of 30-day sub-chronic microcosm experiments, juvenile leader prawns Penaeus monodon, polychaete worms Galeolaria caespitosa and the tropical gastropod Nerita chamaeleon were all very resistant to the nickel ores, with mortality unaffected by 700 g ore per 50 l seawater. The growth rate of the leader prawns was, however, lower than that of the controls. From these data, a conservative maximum safe concentration of the nickel ores in seawater is 0.1 g l-1. The nickel ore was not highly toxic and if spilt in the quantities predicted, would not have a significant impact on the ecological health of the Bay.","Toxicity of nickel ores to marine organisms Abs: Queensland Nickel proposes to import New Caledonian (Ballande) and Indonesian (Gebe) nickel ores, one option being ship-to-barge transfer in Halifax Bay, North Queensland. Because small amounts of ore may be split during the unloading and transfer operations, it was important to investigate the potential impact of the spilt ore on the ecological health of the Bay. Long-term leaching of the ores with seawater showed that only nickel and chromium (VI) were released from the ores in sufficient concentrations to cause toxicity to a range of marine organisms. The soluble fractions of nickel and chromium (VI) were released from the ores within a few days. Nickel, chromium (VI) and the ore leachates showed similar toxicity to the juvenile banana prawn Penaeus merguiensis, the amphipod Allorchestes compressa and both temperature (22 degrees C) and tropical (27 degrees C) strains of the unicellular marine alga Nitzschia closterium. In a series of 30-day sub-chronic microcosm experiments, juvenile leader prawns Penaeus monodon, polychaete worms Galeolaria caespitosa and the tropical gastropod Nerita chamaeleon were all very resistant to the nickel ores, with mortality unaffected by 700 g ore per 50 l seawater. The growth rate of the leader prawns was, however, lower than that of the controls. From these data, a conservative maximum safe concentration of the nickel ores in seawater is 0.1 g l-1. The nickel ore was not highly toxic and if spilt in the quantities predicted, would not have a significant impact on the ecological health of the Bay."
1509544,Corradi et al. 1995,Hexavalent chromium induces gametogenesis in the freshwater alga Scenedesmus acutus,The aggregates formed by Scenedesmus acutus cultivated in the presence of 1 mg/liter Cr(VI) persist even after 7 days of treatment. They were examined by fluorescence and electron microscopy and were found to be an early stage of sexual reproduction. They consist of four small cells deprived of a true cell wall and enclosed in a common envelope. When the envelope breaks up they are released in the culture medium as biflagellated mobile cells. These cells have been identified as gametes.,Hexavalent chromium induces gametogenesis in the freshwater alga Scenedesmus acutus Abs: The aggregates formed by Scenedesmus acutus cultivated in the presence of 1 mg/liter Cr(VI) persist even after 7 days of treatment. They were examined by fluorescence and electron microscopy and were found to be an early stage of sexual reproduction. They consist of four small cells deprived of a true cell wall and enclosed in a common envelope. When the envelope breaks up they are released in the culture medium as biflagellated mobile cells. These cells have been identified as gametes.
1509543,Wilson et al. 1981,Monitoring personnel exposure to stainless steel welding fumes in confined spaces at a petrochemical plant,"This paper documents exposure to stainless steel welding fumes at a petrochemical plant. The situation evaluated may be separated into three categories: 1) evaluation of background concentration levels in a maintenance shop (area monitoring), 2) evaluation of personnel exposures during open air welding in a maintenance shop (personal monitoring), 3) evaluation of personnel exposures in confined space welding (personal monitoring). Thirty-five area samples and seventy-six personal samples were collected and analyzed for chromium (VI), total chromium, nickel, iron, copper, and total particulates. The background concentrations in the maintenance shop were found to be far below those felt to be harmful. Personnel exposures found in the maintenance shop during open air welding were also low, especially when compared to current OSHA permissible exposure levels. Contaminant levels found during confined space welding, as in distillation towers, were considered excessive. After several possible solutions to the problem were considered, it was decided to implement a mandatory air-line respirator program for all employees entering confined spaces during stainless steel welding operations.","Monitoring personnel exposure to stainless steel welding fumes in confined spaces at a petrochemical plant Abs: This paper documents exposure to stainless steel welding fumes at a petrochemical plant. The situation evaluated may be separated into three categories: 1) evaluation of background concentration levels in a maintenance shop (area monitoring), 2) evaluation of personnel exposures during open air welding in a maintenance shop (personal monitoring), 3) evaluation of personnel exposures in confined space welding (personal monitoring). Thirty-five area samples and seventy-six personal samples were collected and analyzed for chromium (VI), total chromium, nickel, iron, copper, and total particulates. The background concentrations in the maintenance shop were found to be far below those felt to be harmful. Personnel exposures found in the maintenance shop during open air welding were also low, especially when compared to current OSHA permissible exposure levels. Contaminant levels found during confined space welding, as in distillation towers, were considered excessive. After several possible solutions to the problem were considered, it was decided to implement a mandatory air-line respirator program for all employees entering confined spaces during stainless steel welding operations."
1509542,Goshgarian and  Rafols 1981,The phrenic nucleus of th albino rat: a correlative HRP and Golgi study,"The phrenic nucleus of the adult albino rat was studied by utilizing the O-dianisidine method for the retrograde transport of horseradish peroxidase in conjunction with the zinc chromate modification of the Golgi technique. Application of HRP to the transected phrenic nerve in the neck labeled a column of phrenic motor neurons from C3 to C5 in the ipsilateral spinal cord. However, when HRP was applied to the phrenic nerve intrathoracically, labeled neurons were found from C3 to C6. The long axis of the column of phrenic neurons was oriented tangentially from rostral to caudal poles. There was a gradual shift of the column from posterior to anterior and from lateral to medial positions in the ventral horn. The peroxidase material was also used to localize impregnated phrenic motor neurons in the Golgi sections and to provide quantitative data on phrenic motor neurons. In Golgi-impregnated material two types of phrenic neurons were distinguished on the basis of dendritic morphology and orientation. These neurons were designated (1) large neurons with smooth, radially oriented dendrites, and (2) smaller neurons with varicose, tangentially oriented dendrites. Both types of neurons had a small number of spines and bulbous appendages issuing from the dendritic trunks and branches. The dendritic fields of adjacent phrenic neurons overlapped extensively with one another and with dendrites of more distally placed ventral horn motor neurons. In peroxidase-labeled sagittal sections the dendrites of phrenic neurons were primarily oriented in the rostrocaudal plane. The mean total number of peroxidase-labeled neurons in the phrenic nucleus was 415.75 +/- 18.36 cells. In sagittal sections the mean long axis diameter of phrenic cell bodies was 34.5 micrometers. In frontal sections the mean long axis diameter of phrenic cell bodies was 22.5 micrometers. Thus, from direct measurement, the phrenic neurons were 34% longer in the sagittal plane than in the frontal plane. In the present study each phrenic nucleus contributed fibers only to the ipsilateral phrenic nerve, and no evidence for peripheral crossing of fibers was found.","The phrenic nucleus of th albino rat: a correlative HRP and Golgi study Abs: The phrenic nucleus of the adult albino rat was studied by utilizing the O-dianisidine method for the retrograde transport of horseradish peroxidase in conjunction with the zinc chromate modification of the Golgi technique. Application of HRP to the transected phrenic nerve in the neck labeled a column of phrenic motor neurons from C3 to C5 in the ipsilateral spinal cord. However, when HRP was applied to the phrenic nerve intrathoracically, labeled neurons were found from C3 to C6. The long axis of the column of phrenic neurons was oriented tangentially from rostral to caudal poles. There was a gradual shift of the column from posterior to anterior and from lateral to medial positions in the ventral horn. The peroxidase material was also used to localize impregnated phrenic motor neurons in the Golgi sections and to provide quantitative data on phrenic motor neurons. In Golgi-impregnated material two types of phrenic neurons were distinguished on the basis of dendritic morphology and orientation. These neurons were designated (1) large neurons with smooth, radially oriented dendrites, and (2) smaller neurons with varicose, tangentially oriented dendrites. Both types of neurons had a small number of spines and bulbous appendages issuing from the dendritic trunks and branches. The dendritic fields of adjacent phrenic neurons overlapped extensively with one another and with dendrites of more distally placed ventral horn motor neurons. In peroxidase-labeled sagittal sections the dendrites of phrenic neurons were primarily oriented in the rostrocaudal plane. The mean total number of peroxidase-labeled neurons in the phrenic nucleus was 415.75 +/- 18.36 cells. In sagittal sections the mean long axis diameter of phrenic cell bodies was 34.5 micrometers. In frontal sections the mean long axis diameter of phrenic cell bodies was 22.5 micrometers. Thus, from direct measurement, the phrenic neurons were 34% longer in the sagittal plane than in the frontal plane. In the present study each phrenic nucleus contributed fibers only to the ipsilateral phrenic nerve, and no evidence for peripheral crossing of fibers was found."
1509540,Kalliomäki et al. 1983,Stainless steel manual metal arc welding fumes in rats,"Forty two male Wistar rats were exposed to manual metal arc (MMA) stainless steel (SS) welding fumes generated by an automatic welding device for &quot;nose-only&quot; exposure. The exposure simulated an actual MMA/SS welding environment as closely as possible. For the retention study, the duration of exposure was one hour per workday for one, two, three, of four weeks and for the clearance study four weeks. The retention and clearance of the chromium, nickel, and iron found in MMA/SS welding fumes in the rats' lungs were studied as was the distribution of the metals to other organs. Instrumental neutron activation analysis (INAA) was used for the multi-element chemical activation analyses. The concentrations of chromium and nickel in the blood and the urine were determined by atomic absorption method (AAS). The retention of exogenous iron was determined by a magnetic measuring method. The results indicated that the lungs were the target organs of soluble hexavalent chromates. The half times of lung clearance for Cr, Ni, and Fe were 40 +/- 4 d, 20 +/- d, and 50 +/- 10 d. When the lung clearance curves are compared, the half times of Cr and Fe lung clearance are similar but nickel disappears faster. The distribution and clearance patterns of chromium to other organs differ from those obtained after single intravenous or intratracheal injections of alkaline chromates.","Stainless steel manual metal arc welding fumes in rats Abs: Forty two male Wistar rats were exposed to manual metal arc (MMA) stainless steel (SS) welding fumes generated by an automatic welding device for &quot;nose-only&quot; exposure. The exposure simulated an actual MMA/SS welding environment as closely as possible. For the retention study, the duration of exposure was one hour per workday for one, two, three, of four weeks and for the clearance study four weeks. The retention and clearance of the chromium, nickel, and iron found in MMA/SS welding fumes in the rats' lungs were studied as was the distribution of the metals to other organs. Instrumental neutron activation analysis (INAA) was used for the multi-element chemical activation analyses. The concentrations of chromium and nickel in the blood and the urine were determined by atomic absorption method (AAS). The retention of exogenous iron was determined by a magnetic measuring method. The results indicated that the lungs were the target organs of soluble hexavalent chromates. The half times of lung clearance for Cr, Ni, and Fe were 40 +/- 4 d, 20 +/- d, and 50 +/- 10 d. When the lung clearance curves are compared, the half times of Cr and Fe lung clearance are similar but nickel disappears faster. The distribution and clearance patterns of chromium to other organs differ from those obtained after single intravenous or intratracheal injections of alkaline chromates."
1509539,Mclean et al. 1983,The effect of tin chloride on the structure and function of DNA in human white blood cells,"Tin compounds are being used increasingly in the home, in industry and in medicine. There have been relatively few studies on the long term biological effects of this metal, although acute effects have been documented. In this report we describe experiments which show that tin(II), as stannous chloride, is readily taken up by human white blood cells (WBC) and can cause damage to DNA. Damage was detected in WBC after exposure to 10-50 microM tin(II) for 30 min at either 0 degree or 37 degrees C. The amount of damage observed was more extensive than that produced by exposure of cells to equimolar amounts of chromium(VI), a known carcinogen and DNA damaging agent. Additional indication of cellular damage is that exposure of human lymphocytes or mouse splenocytes to tin(II) interfered with their ability to be stimulated by the polyvalent mitogen concanavalin A (Con A). By contrast, tin(IV) was not taken up by cells, did not cause DNA damage nor did it inhibit stimulation of DNA synthesis in cells that were exposed to Con A.","The effect of tin chloride on the structure and function of DNA in human white blood cells Abs: Tin compounds are being used increasingly in the home, in industry and in medicine. There have been relatively few studies on the long term biological effects of this metal, although acute effects have been documented. In this report we describe experiments which show that tin(II), as stannous chloride, is readily taken up by human white blood cells (WBC) and can cause damage to DNA. Damage was detected in WBC after exposure to 10-50 microM tin(II) for 30 min at either 0 degree or 37 degrees C. The amount of damage observed was more extensive than that produced by exposure of cells to equimolar amounts of chromium(VI), a known carcinogen and DNA damaging agent. Additional indication of cellular damage is that exposure of human lymphocytes or mouse splenocytes to tin(II) interfered with their ability to be stimulated by the polyvalent mitogen concanavalin A (Con A). By contrast, tin(IV) was not taken up by cells, did not cause DNA damage nor did it inhibit stimulation of DNA synthesis in cells that were exposed to Con A."
1509538,Smith et al. 1984,The determination of leachable chromium from chromicized catgut sutures,Application of the British Pharmacopoeia (BP) Analytical procedure for the determination of leachable chromium to samples of catgut sutures yielded fading coloured solutions and was considered to constitute a poor basis for an analytical method. The United States Pharmacopeia (USP) method and an adaptation of the American Public Health Association (APHA) method were explored and found to give linear responses over the concentration range of interest. Both these methods were applied to a series of samples and the results obtained were different as the APHA method measures total chromium while the USP procedure determines only chromium (VI).,The determination of leachable chromium from chromicized catgut sutures Abs: Application of the British Pharmacopoeia (BP) Analytical procedure for the determination of leachable chromium to samples of catgut sutures yielded fading coloured solutions and was considered to constitute a poor basis for an analytical method. The United States Pharmacopeia (USP) method and an adaptation of the American Public Health Association (APHA) method were explored and found to give linear responses over the concentration range of interest. Both these methods were applied to a series of samples and the results obtained were different as the APHA method measures total chromium while the USP procedure determines only chromium (VI).
1509536,Wapner et al. 1986,Release of corrosion products by F-75 cobalt base alloy in the rat. II: Morbidity apparently associated with chromium release in vivo: a 120-day rat study,"There is concern whether in vivo corrosion of chromium-cobalt alloys releases ions containing trivalent [Cr(III)] or hexavalent [Cr(VI)] chromium. The question arises from indications that Cr(VI) is far more biologically active than Cr(III). Using a previously developed microsphere implant model, specimens of F-75 chromium-cobalt-molybdenum alloy were implanted in rats for periods up to 120 days. Blood and urine were collected at intervals during the study. Significant postoperative serum and urine chromium concentration elevations were observed. In addition, weight gain inhibition, lung morbidity, and animal mortality, related to the implant surface area to animal body weight ratio (SA/BW), were observed. Comparison of measured chromium serum concentrations with those concentrations found by others to be biologically active in tissue culture studies strongly suggests the release of Cr(VI) in this study.","Release of corrosion products by F-75 cobalt base alloy in the rat. II: Morbidity apparently associated with chromium release in vivo: a 120-day rat study Abs: There is concern whether in vivo corrosion of chromium-cobalt alloys releases ions containing trivalent [Cr(III)] or hexavalent [Cr(VI)] chromium. The question arises from indications that Cr(VI) is far more biologically active than Cr(III). Using a previously developed microsphere implant model, specimens of F-75 chromium-cobalt-molybdenum alloy were implanted in rats for periods up to 120 days. Blood and urine were collected at intervals during the study. Significant postoperative serum and urine chromium concentration elevations were observed. In addition, weight gain inhibition, lung morbidity, and animal mortality, related to the implant surface area to animal body weight ratio (SA/BW), were observed. Comparison of measured chromium serum concentrations with those concentrations found by others to be biologically active in tissue culture studies strongly suggests the release of Cr(VI) in this study."
1509535,Zelenský et al. 1987,Isotachophoretic determination of chromium(VI) at low parts per billion concentrations,"Factors important in the isotachophoretic determination of CrVI at low ppb concentrations were studied. To increase the selectivity of the analysis, the use of photometric detection at a 405 wavelength was preferred. Losses of CrVI due to adsorption were found to be the main potential source of analytical errors at the concentration levels of interest. The presence of sulphate in the sample solution at ca. 10(-4) M concentration eliminated the losses due to adsorption on the walls of the sample handling glassware. In analysis with a low pH of the leading electrolyte, adsorption of CrVI on the walls of the separation compartment also played a role; addition of naphthalene-1,3,6-trisulphonate to the sample solution considerably reduced this disturbance. When the precautions concerning adsorption were taken, the detection limits for CrVI were in the range 4-5 ppb (depending on the pH of the leading electrolyte) for a 30-microliters sample volume. The calibration graphs were linear over the concentration range 10(-7)-5 X 10(-6) M with good correlation coefficients. The reproducibilities of the determinations within this concentration range were 2-3% or better. The practical utility of capillary isotachophoresis in the trace determination of CrVI in drinking water and wastewater samples seems promising.","Isotachophoretic determination of chromium(VI) at low parts per billion concentrations Abs: Factors important in the isotachophoretic determination of CrVI at low ppb concentrations were studied. To increase the selectivity of the analysis, the use of photometric detection at a 405 wavelength was preferred. Losses of CrVI due to adsorption were found to be the main potential source of analytical errors at the concentration levels of interest. The presence of sulphate in the sample solution at ca. 10(-4) M concentration eliminated the losses due to adsorption on the walls of the sample handling glassware. In analysis with a low pH of the leading electrolyte, adsorption of CrVI on the walls of the separation compartment also played a role; addition of naphthalene-1,3,6-trisulphonate to the sample solution considerably reduced this disturbance. When the precautions concerning adsorption were taken, the detection limits for CrVI were in the range 4-5 ppb (depending on the pH of the leading electrolyte) for a 30-microliters sample volume. The calibration graphs were linear over the concentration range 10(-7)-5 X 10(-6) M with good correlation coefficients. The reproducibilities of the determinations within this concentration range were 2-3% or better. The practical utility of capillary isotachophoresis in the trace determination of CrVI in drinking water and wastewater samples seems promising."
1509534,Burrows 1986,"Hypersensitivity to mercury, nickel and chromium in relation to dental materials","Three metals which are used in dental materials are recognized as causing sensitization sufficiently frequently to consider whether problems might arise from their use in dentistry. These metals are, mercury, nickel and chromium. Nickel is by far the commonest sensitizer, 10 per cent of women are allergic to nickel; sensitization usually occurs through jewellery or fasteners on articles of clothing. Chromium (as chromate) is a much less common sensitizer for several reasons. Sensitization only occurs through hexavalent salts of chromate and the degree of exposure of humans to these salts is much less than to either nickel or mercury. The true incidence of mercury sensitization is difficult to ascertain because many of the materials which were used for patch testing previously and on which statistics were based, contained unnecessarily high concentrations of mercury, and the pattern of mercury allergy is changing because many substances which contain mercury and were used frequently are not now employed. Although metallic mercury can sensitize the evidence would suggest that if dental amalgams ever cause people to become allergic to mercury, it is an extremely rare occurrence. Problems with mercury-containing amalgams in those sensitized are also rare, only 28 cases have been recorded in the literature. Thus, it is likely that at the present time sensitization to mercury is uncommon and decreasing. There is even less evidence that nickel or chromate in dental materials actively sensitize and it is exceptionally rare to have problems with these metals in a prosthesis in someone who is already sensitized.(ABSTRACT TRUNCATED AT 250 WORDS)","Hypersensitivity to mercury, nickel and chromium in relation to dental materials Abs: Three metals which are used in dental materials are recognized as causing sensitization sufficiently frequently to consider whether problems might arise from their use in dentistry. These metals are, mercury, nickel and chromium. Nickel is by far the commonest sensitizer, 10 per cent of women are allergic to nickel; sensitization usually occurs through jewellery or fasteners on articles of clothing. Chromium (as chromate) is a much less common sensitizer for several reasons. Sensitization only occurs through hexavalent salts of chromate and the degree of exposure of humans to these salts is much less than to either nickel or mercury. The true incidence of mercury sensitization is difficult to ascertain because many of the materials which were used for patch testing previously and on which statistics were based, contained unnecessarily high concentrations of mercury, and the pattern of mercury allergy is changing because many substances which contain mercury and were used frequently are not now employed. Although metallic mercury can sensitize the evidence would suggest that if dental amalgams ever cause people to become allergic to mercury, it is an extremely rare occurrence. Problems with mercury-containing amalgams in those sensitized are also rare, only 28 cases have been recorded in the literature. Thus, it is likely that at the present time sensitization to mercury is uncommon and decreasing. There is even less evidence that nickel or chromate in dental materials actively sensitize and it is exceptionally rare to have problems with these metals in a prosthesis in someone who is already sensitized.(ABSTRACT TRUNCATED AT 250 WORDS)"
1509531,Wolf et al. 1989,Molecular interaction of different chromium species with nucleotides and nucleic acids,"The interaction of chromium(III) and chromium(VI) with the phosphate groups of di- and triphosphate nucleotides were examined by 31P-NMR spectroscopy. Chemical shifts of the phosphate groups, indicating the formation of Cr-nucleotide complexes, could only be detected with Cr(III). When Cr(III) was generated from Cr(VI) by reduction with an excess of glutathione, nearly the same chemical shifts could be observed. This indicates that glutathione is not capable of trapping Cr(VI) by reduction with subsequent formation of stable Cr-GSH complexes, thus preventing the binding of chromium to important target molecules as DNA or nucleotides. Using radioactively-labelled chromium no 51Cr(VI) bound to any nucleic acid, whereas 51Cr(III) bound in increasing order to poly(A).poly(U), calf thymus DNA and poly(G).poly(C). Furthermore, the melting temperature of nucleic acids increased in the same order only in the presence of Cr(III). Possible genotoxic consequences in vivo of the presented data in vitro concerning the binding of Cr(III) to sensitive molecular targets are discussed in detail.","Molecular interaction of different chromium species with nucleotides and nucleic acids Abs: The interaction of chromium(III) and chromium(VI) with the phosphate groups of di- and triphosphate nucleotides were examined by 31P-NMR spectroscopy. Chemical shifts of the phosphate groups, indicating the formation of Cr-nucleotide complexes, could only be detected with Cr(III). When Cr(III) was generated from Cr(VI) by reduction with an excess of glutathione, nearly the same chemical shifts could be observed. This indicates that glutathione is not capable of trapping Cr(VI) by reduction with subsequent formation of stable Cr-GSH complexes, thus preventing the binding of chromium to important target molecules as DNA or nucleotides. Using radioactively-labelled chromium no 51Cr(VI) bound to any nucleic acid, whereas 51Cr(III) bound in increasing order to poly(A).poly(U), calf thymus DNA and poly(G).poly(C). Furthermore, the melting temperature of nucleic acids increased in the same order only in the presence of Cr(III). Possible genotoxic consequences in vivo of the presented data in vitro concerning the binding of Cr(III) to sensitive molecular targets are discussed in detail."
1509530,Baldi et al. 1990,Chromium(VI)-resistant yeast isolated from a sewage treatment plant receiving tannery wastes,"A Cr(VI)-resistant yeast, designated strain DBVPG 6502, was isolated from a sewage treatment plant receiving wastes from tannery industries in Italy. The strain was tentatively identified as a species of Candida based on morphological and physiological analyses. This strain was highly resistant to Cr(VI) when compared with eight other yeast species, growing at Cr(VI) concentrations of up to 500 micrograms/ml (10 mM). This resistance was constitutive. The Cr(VI)-resistant yeast did not reduce Cr(VI) to Cr(III) species under aerobic conditions. The yeast showed very little accumulation of Cr(VI). Consequently, the mechanism of resistance of the yeast to Cr(VI) appears to involve reduced accumulation of Cr, as has been shown in Cr(VI)-resistant bacteria.","Chromium(VI)-resistant yeast isolated from a sewage treatment plant receiving tannery wastes Abs: A Cr(VI)-resistant yeast, designated strain DBVPG 6502, was isolated from a sewage treatment plant receiving wastes from tannery industries in Italy. The strain was tentatively identified as a species of Candida based on morphological and physiological analyses. This strain was highly resistant to Cr(VI) when compared with eight other yeast species, growing at Cr(VI) concentrations of up to 500 micrograms/ml (10 mM). This resistance was constitutive. The Cr(VI)-resistant yeast did not reduce Cr(VI) to Cr(III) species under aerobic conditions. The yeast showed very little accumulation of Cr(VI). Consequently, the mechanism of resistance of the yeast to Cr(VI) appears to involve reduced accumulation of Cr, as has been shown in Cr(VI)-resistant bacteria."
1509529,Bartlett 1991,"Chromium cycling in soils and water: links, gaps, and methods","The major links in the cycling of chromium in soils and in natural waters are between chromium(III) and chromium (VI). Between the larger links are lesser links involving processes of mobilization and oxidation of CrIII and reduction of CrVI. The gaps are mainly in our understanding of the factors that control these processes. If soluble CrIII is added to an &quot;average&quot; soil, a portion of it will become immediately oxidized by manganese oxides to CrVI. The rest of the CrIII may remain reduced for long periods of time, even in the presence of electron-accepting manganese oxides. However, this less available CrIII can be mobilized by low molecular weight organic complexers and then oxidized where redox conditions are optimal. Usually part of any CrVI added to a soil or sediment will be reduced instantly, especially under acid conditions. On the other hand, high concentrations of polluting CrVI may quickly exhaust the readily available reducing power of the matrix material and excess CrVI, the thermodynamically stable form in air, may persist for years in soils or lagoons without reduction. Cleanup of chromium pollution must involve the surrounding of both CrIII and CrVI with excesses of slowly available reducing substances and sealing them permanently from inputs of atmospheric oxygen. Monitoring the effectiveness of the measures is mandatory, but fortunately the chemical testing for CrVI in soil and water is simple and problem free compared with most colorimetric determinations.","Chromium cycling in soils and water: links, gaps, and methods Abs: The major links in the cycling of chromium in soils and in natural waters are between chromium(III) and chromium (VI). Between the larger links are lesser links involving processes of mobilization and oxidation of CrIII and reduction of CrVI. The gaps are mainly in our understanding of the factors that control these processes. If soluble CrIII is added to an &quot;average&quot; soil, a portion of it will become immediately oxidized by manganese oxides to CrVI. The rest of the CrIII may remain reduced for long periods of time, even in the presence of electron-accepting manganese oxides. However, this less available CrIII can be mobilized by low molecular weight organic complexers and then oxidized where redox conditions are optimal. Usually part of any CrVI added to a soil or sediment will be reduced instantly, especially under acid conditions. On the other hand, high concentrations of polluting CrVI may quickly exhaust the readily available reducing power of the matrix material and excess CrVI, the thermodynamically stable form in air, may persist for years in soils or lagoons without reduction. Cleanup of chromium pollution must involve the surrounding of both CrIII and CrVI with excesses of slowly available reducing substances and sealing them permanently from inputs of atmospheric oxygen. Monitoring the effectiveness of the measures is mandatory, but fortunately the chemical testing for CrVI in soil and water is simple and problem free compared with most colorimetric determinations."
1509528,Burke et al. 1991,"Chromite ore processing residue in Hudson County, New Jersey","Chromite ore processing residue occurs at over 130 sites in Hudson County, New Jersey. Many of these sites are in urban residential areas. This waste is a result of 70 years of chromate and bichromate chemical manufacturing. At least 15% of the sites contain total chromium concentrations greater than 10,000 mg/kg, with hexavalent content ranging from about 1 to 50%. Continuing leaching of this waste results in yellow-colored surface water runoff and yellow deposits on the soil surface and inside basement walls. The chemistry, environmental fate, health effects, and human exposure potentials for this waste are described.","Chromite ore processing residue in Hudson County, New Jersey Abs: Chromite ore processing residue occurs at over 130 sites in Hudson County, New Jersey. Many of these sites are in urban residential areas. This waste is a result of 70 years of chromate and bichromate chemical manufacturing. At least 15% of the sites contain total chromium concentrations greater than 10,000 mg/kg, with hexavalent content ranging from about 1 to 50%. Continuing leaching of this waste results in yellow-colored surface water runoff and yellow deposits on the soil surface and inside basement walls. The chemistry, environmental fate, health effects, and human exposure potentials for this waste are described."
1509526,Lee et al. 1992,A novel microbial sensor using luminous bacteria,"A novel microbial sensor system that uses luminous bacteria was developed for the determination of both glucose and toxic compounds. The sensor system consisted of a membrane with luminous bacteria immobilized upon it and a photomultiplier. Measurements were based on the in vivo intensity of the light emitted by the bacteria, as this is affected by their environment. A linear relationship was observed between increased luminescence and concentrations of glucose between 0.05 mM and 0.55 mM. The relative standard deviation was 10% for 0.55 mM glucose (n = 10). Toxic compounds such as benzalkonium chloride, sodium dodecyl sulphate and chromium(VI) were also detected by measuring the decrease in luminescence in their presence.","A novel microbial sensor using luminous bacteria Abs: A novel microbial sensor system that uses luminous bacteria was developed for the determination of both glucose and toxic compounds. The sensor system consisted of a membrane with luminous bacteria immobilized upon it and a photomultiplier. Measurements were based on the in vivo intensity of the light emitted by the bacteria, as this is affected by their environment. A linear relationship was observed between increased luminescence and concentrations of glucose between 0.05 mM and 0.55 mM. The relative standard deviation was 10% for 0.55 mM glucose (n = 10). Toxic compounds such as benzalkonium chloride, sodium dodecyl sulphate and chromium(VI) were also detected by measuring the decrease in luminescence in their presence."
1509525,Sperling et al. 1992,Differential determination of chromium(VI) and total chromium in natural waters using flow injection on-line separation and preconcentration electrothermal atomic absorption spectrometry,"A rapid, sensitive and selective method for the differential determination of CrIII and CrVI in natural waters is described. Chromium(vi) can be determined directly by flow injection on-line sorbent extraction preconcentration coupled with electrothermal atomic absorption spectrometry using sodium diethyldithiocarbamate as the complexing agent and C18 bonded silica reversed-phase sorbent as the column material. Total Cr can be determined after oxidation of CrIII to CrVI by potassium peroxydisulfate. Chromium(III) can be calculated by difference. The optimum conditions for sorbent extraction of CrVI and oxidation of CrIII to CrVI are evaluated. A 12-fold enhancement in sensitivity compared with direct introduction of 40 microliters samples was achieved after preconcentration for 60 s, giving detection limits of 16 ng l-1 for CrVI and 18 ng l-1 for total Cr (based on 3 sigma). Results obtained for sea-water and river water reference materials were all within the certified range for total Cr with a precision of better than 10% relative standard deviation in the range 100-200 ng l-1. The selectivity of the determination of CrVI was evaluated by analysing spiked reference materials in the presence of CrIII, resulting in quantitative recovery of CrVI.","Differential determination of chromium(VI) and total chromium in natural waters using flow injection on-line separation and preconcentration electrothermal atomic absorption spectrometry Abs: A rapid, sensitive and selective method for the differential determination of CrIII and CrVI in natural waters is described. Chromium(vi) can be determined directly by flow injection on-line sorbent extraction preconcentration coupled with electrothermal atomic absorption spectrometry using sodium diethyldithiocarbamate as the complexing agent and C18 bonded silica reversed-phase sorbent as the column material. Total Cr can be determined after oxidation of CrIII to CrVI by potassium peroxydisulfate. Chromium(III) can be calculated by difference. The optimum conditions for sorbent extraction of CrVI and oxidation of CrIII to CrVI are evaluated. A 12-fold enhancement in sensitivity compared with direct introduction of 40 microliters samples was achieved after preconcentration for 60 s, giving detection limits of 16 ng l-1 for CrVI and 18 ng l-1 for total Cr (based on 3 sigma). Results obtained for sea-water and river water reference materials were all within the certified range for total Cr with a precision of better than 10% relative standard deviation in the range 100-200 ng l-1. The selectivity of the determination of CrVI was evaluated by analysing spiked reference materials in the presence of CrIII, resulting in quantitative recovery of CrVI."
1509523,Suzuki et al. 1992,NAD(P)H-dependent chromium (VI) reductase of Pseudomonas ambigua G-1: a Cr(V) intermediate is formed during the reduction of Cr(VI) to Cr(III),"An NAD(P)H-dependent Cr(VI) reductase (molecular weight = 65,000) was purified from a Cr(VI)-resistant bacterium, Pseudomonas ambigua G-1. Stoichiometric analysis of the enzymatic reaction showed that the enzyme catalyzed the reduction of 1 mol of Cr(VI) to Cr(III) while consuming 3 mol of NADH as an electron donor. Chromium(VI) was reduced to Cr(V) by one equivalent NADH molecule in the absence of the enzyme. Electron spin resonance analysis showed that Cr(V) species (g = 1.979) was formed during the enzymatic reduction. The amount of Cr(V) species formed was about 10 times larger than that of the nonezymatic reduction. These findings show that the Cr(VI) reductase reduced Cr(VI) to Cr(III) with at least two reaction steps via Cr(V) as an intermediate.","NAD(P)H-dependent chromium (VI) reductase of Pseudomonas ambigua G-1: a Cr(V) intermediate is formed during the reduction of Cr(VI) to Cr(III) Abs: An NAD(P)H-dependent Cr(VI) reductase (molecular weight = 65,000) was purified from a Cr(VI)-resistant bacterium, Pseudomonas ambigua G-1. Stoichiometric analysis of the enzymatic reaction showed that the enzyme catalyzed the reduction of 1 mol of Cr(VI) to Cr(III) while consuming 3 mol of NADH as an electron donor. Chromium(VI) was reduced to Cr(V) by one equivalent NADH molecule in the absence of the enzyme. Electron spin resonance analysis showed that Cr(V) species (g = 1.979) was formed during the enzymatic reduction. The amount of Cr(V) species formed was about 10 times larger than that of the nonezymatic reduction. These findings show that the Cr(VI) reductase reduced Cr(VI) to Cr(III) with at least two reaction steps via Cr(V) as an intermediate."
1509521,Barr et al. 1976,A reappraisal of cellular labeling with radiochromium salts,"The present studies demonstrate that, while erythrocytes preferentially bind hexavalent 51Cr, leukocytes bind the trivalent form with equal avidity. Red cells may be saturated with label in contrast to the binding of 51Cr to leukocytes, which may be described by first-order kinetics. Hexavalent label is rapidly reduced in leukocytes in contradistinction to the finding in red cells. The nonreutilization of label by erythrocytes and leukocytes is not due to inappropriate valency but to protein binding of the label. Unlike nonleukemic cells, leukemic leukocytes elute a large fraction of their label. These factors have been largely overlooked in many previous clinical studies using labeled cells, and they are of sufficient quantitative importance to compromise seriously the validity of numerous earlier reports.","A reappraisal of cellular labeling with radiochromium salts Abs: The present studies demonstrate that, while erythrocytes preferentially bind hexavalent 51Cr, leukocytes bind the trivalent form with equal avidity. Red cells may be saturated with label in contrast to the binding of 51Cr to leukocytes, which may be described by first-order kinetics. Hexavalent label is rapidly reduced in leukocytes in contradistinction to the finding in red cells. The nonreutilization of label by erythrocytes and leukocytes is not due to inappropriate valency but to protein binding of the label. Unlike nonleukemic cells, leukemic leukocytes elute a large fraction of their label. These factors have been largely overlooked in many previous clinical studies using labeled cells, and they are of sufficient quantitative importance to compromise seriously the validity of numerous earlier reports."
1509520,Lautner et al. 1978,Measurement of chromium VI and chromium III in stainless steel welding fumes with electrom spectroscopy for chemical analysis and neutron activation analysis,Electron Spectroscopy for Chemical Analysis (ESCA) was explored as a means of studying the oxidation state of chromium in SMAC (coated electrode) stainless steel welding fume collected on Nucleopore filters in the laboratory. Chromuim VI and III (as a percent of the total chromium) obtained from ESCA analysis was applied to results from Neutron Activation Analysis (NAA) to yield an average of 69 microgram chromium VI per sample. Diphenylcarbazide/atomic absorption (DPC/AA) results are reported for samples submitted to an industrial laboratory. Possible chemical species and solubility of chromium VI in stainless steel fumes is discussed in light of analogy between the SMAC process and the manufacturing process for chromates.,Measurement of chromium VI and chromium III in stainless steel welding fumes with electrom spectroscopy for chemical analysis and neutron activation analysis Abs: Electron Spectroscopy for Chemical Analysis (ESCA) was explored as a means of studying the oxidation state of chromium in SMAC (coated electrode) stainless steel welding fume collected on Nucleopore filters in the laboratory. Chromuim VI and III (as a percent of the total chromium) obtained from ESCA analysis was applied to results from Neutron Activation Analysis (NAA) to yield an average of 69 microgram chromium VI per sample. Diphenylcarbazide/atomic absorption (DPC/AA) results are reported for samples submitted to an industrial laboratory. Possible chemical species and solubility of chromium VI in stainless steel fumes is discussed in light of analogy between the SMAC process and the manufacturing process for chromates.
1509519,Kuhnert et al. 1976,The effect of in vivo chromium exposure on Na/K-and Mg-ATPase activity in several tissues of the rainbow trout (Salmo gairdneri),"The effect of in vivo chromium exposure on Na/K-and Mg-ATPase activity was studied in several tissues of the rainbow trout, Salmo gairdneri. Those tissues studied were: intestine, gill, liver, and kidney. Tissue chromium levels were determined for control rainbow trout and trout exposed to 2.5 mg Cr/1 (as chromate) for 48 hours. After exposure to chromium, inhibition of Na/K-ATPase activity, but not Mg ATPase activity, was observed. These results may partially explain the detrimental effects of hexavalent chromium on fish.","The effect of in vivo chromium exposure on Na/K-and Mg-ATPase activity in several tissues of the rainbow trout (Salmo gairdneri) Abs: The effect of in vivo chromium exposure on Na/K-and Mg-ATPase activity was studied in several tissues of the rainbow trout, Salmo gairdneri. Those tissues studied were: intestine, gill, liver, and kidney. Tissue chromium levels were determined for control rainbow trout and trout exposed to 2.5 mg Cr/1 (as chromate) for 48 hours. After exposure to chromium, inhibition of Na/K-ATPase activity, but not Mg ATPase activity, was observed. These results may partially explain the detrimental effects of hexavalent chromium on fish."
1509518,Forslind and  Wahlberg 1977,Assessment of chromium allergy: features of patch test reactions at electron microscopic resolution,"The possible correlation of clinically recorded test reactions and morphological changes at electron microscopic resolution in human subjects allergic to chromate (CrVI) was investigated. The effect of simple occlusion and of vehicles, e.g. distilled water, an alkaline buffer, and petrolatum was also studied 72 hours after application. The results indicate that even simple occlusion causes reactive changes in living epidermal cells. These changes become conspicuous in occlusion with distilled water, more pronounced with petrolatum, and were destructive in the case of the alkaline buffer. Chromate solutions produced varying degress of morphological change but were less pronounced in a vehicle of distilled water, compared with the changes seen when the chromate was combined with the alkaline buffer. Destructive cellular changes were observed in the electron microscope even in sections from test ares where no macroscopical reactions were recorded. When the clinical evaluation of hypersensitivity was done 72 hours after the application of the patch test the morphological changes were too advanced to provide specific pathognomonic information.","Assessment of chromium allergy: features of patch test reactions at electron microscopic resolution Abs: The possible correlation of clinically recorded test reactions and morphological changes at electron microscopic resolution in human subjects allergic to chromate (CrVI) was investigated. The effect of simple occlusion and of vehicles, e.g. distilled water, an alkaline buffer, and petrolatum was also studied 72 hours after application. The results indicate that even simple occlusion causes reactive changes in living epidermal cells. These changes become conspicuous in occlusion with distilled water, more pronounced with petrolatum, and were destructive in the case of the alkaline buffer. Chromate solutions produced varying degress of morphological change but were less pronounced in a vehicle of distilled water, compared with the changes seen when the chromate was combined with the alkaline buffer. Destructive cellular changes were observed in the electron microscope even in sections from test ares where no macroscopical reactions were recorded. When the clinical evaluation of hypersensitivity was done 72 hours after the application of the patch test the morphological changes were too advanced to provide specific pathognomonic information."
1508590,Orescanin et al. 2013,Preparation of drinking water used in water supply systems of the towns Zrenjanin and Temerin by electrochemical methods,"The aim of this work was the development and application of the pilot plant with the capacity of 1000 L/day for the purification of groundwater used for human consumption characterized with high concentration of arsenic and increased values of organic pollutants, ammonia, nitrites, color and turbidity. For that purpose, groundwater from the production wells supplying the towns Zrenjanin and Temerin (Vojvodina, Serbia) was used. Due to its complex composition, the purification system required the combination of the electroreduction/electrocoagulation, using iron and aluminum electrode plates with/without ozonation, followed by the electromagnetic treatment and the finally by the simultaneous ozonation/UV treatment. The electroreduction was used for the removal of nitrates, nitrites, and Cr(VI), while the removal of arsenic, heavy metals, suspended solids, color and turbidity required the application of the electrocoagulation with simultaneous ozonation. Organic contaminants and ammonia were removed completely in the last treatment step by applying the simultaneous ozonation/UV treatment. All measured parameters in the purified water were significantly lower compared to the regulated values. Under the optimum treatment conditions, the removal efficiencies for color, turbidity, suspended solids, total arsenic, total chromium, Ni(II), total copper, sulfates, fluorides, chemical oxygen demand, ammonia, nitrates, and nitrites were 100%. The removal efficiencies of the total manganese and iron were 85.19% and 97.44%, respectively, whilst the final concentrations were 4 and 7 ?g/L, respectively.","Preparation of drinking water used in water supply systems of the towns Zrenjanin and Temerin by electrochemical methods Abs: The aim of this work was the development and application of the pilot plant with the capacity of 1000 L/day for the purification of groundwater used for human consumption characterized with high concentration of arsenic and increased values of organic pollutants, ammonia, nitrites, color and turbidity. For that purpose, groundwater from the production wells supplying the towns Zrenjanin and Temerin (Vojvodina, Serbia) was used. Due to its complex composition, the purification system required the combination of the electroreduction/electrocoagulation, using iron and aluminum electrode plates with/without ozonation, followed by the electromagnetic treatment and the finally by the simultaneous ozonation/UV treatment. The electroreduction was used for the removal of nitrates, nitrites, and Cr(VI), while the removal of arsenic, heavy metals, suspended solids, color and turbidity required the application of the electrocoagulation with simultaneous ozonation. Organic contaminants and ammonia were removed completely in the last treatment step by applying the simultaneous ozonation/UV treatment. All measured parameters in the purified water were significantly lower compared to the regulated values. Under the optimum treatment conditions, the removal efficiencies for color, turbidity, suspended solids, total arsenic, total chromium, Ni(II), total copper, sulfates, fluorides, chemical oxygen demand, ammonia, nitrates, and nitrites were 100%. The removal efficiencies of the total manganese and iron were 85.19% and 97.44%, respectively, whilst the final concentrations were 4 and 7 ?g/L, respectively."
1508573,Setton et al. 2013,Risk-based indicators of Canadians' exposures to environmental carcinogens,"ABSTRACT: BACKGROUND: Tools for estimating population exposures to environmental carcinogens are required to support evidence-based policies to reduce chronic exposures and associated cancers. Our objective was to develop indicators of population exposure to selected environmental carcinogens that can be easily updated over time, and allow comparisons and prioritization between different carcinogens and exposure pathways. METHODS: We employed a risk assessment-based approach to produce screening-level estimates of lifetime excess cancer risk for selected substances listed as known carcinogens by the International Agency for Research on Cancer. Estimates of lifetime average daily intake were calculated using population characteristics combined with concentrations (circa 2006) in outdoor air, indoor air, dust, drinking water, and food and beverages from existing monitoring databases or comprehensive literature reviews. Intake estimates were then multiplied by cancer potency factors from Health Canada, the United States Environmental Protection Agency, and the California Office of Environmental Health Hazard Assessment to estimate lifetime excess cancer risks associated with each substance and exposure pathway. Lifetime excess cancer risks in excess of 1 per million people are identified as potential priorities for further attention. RESULTS: Based on data representing average conditions circa 2006, a total of 18 carcinogen-exposure pathways had potential lifetime excess cancer risks greater than 1 per million, based on varying data quality. Carcinogens with moderate to high data quality and lifetime excess cancer risk greater than 1 per million included benzene, 1,3-butadiene and radon in outdoor air; benzene and radon in indoor air; and arsenic and hexavalent chromium in drinking water. Important data gaps were identified for asbestos, hexavalent chromium and diesel exhaust in outdoor and indoor air, while little data were available to assess risk for substances in dust, food and beverages. CONCLUSIONS: The ability to track changes in potential population exposures to environmental carcinogens over time, as well as to compare between different substances and exposure pathways, is necessary to support comprehensive, evidence-based prevention policy. We used estimates of lifetime excess cancer risk as indicators that, although based on a number of simplifying assumptions, help to identify important data gaps and prioritize more detailed data collection and exposure assessment needs.","Risk-based indicators of Canadians' exposures to environmental carcinogens Abs: ABSTRACT: BACKGROUND: Tools for estimating population exposures to environmental carcinogens are required to support evidence-based policies to reduce chronic exposures and associated cancers. Our objective was to develop indicators of population exposure to selected environmental carcinogens that can be easily updated over time, and allow comparisons and prioritization between different carcinogens and exposure pathways. METHODS: We employed a risk assessment-based approach to produce screening-level estimates of lifetime excess cancer risk for selected substances listed as known carcinogens by the International Agency for Research on Cancer. Estimates of lifetime average daily intake were calculated using population characteristics combined with concentrations (circa 2006) in outdoor air, indoor air, dust, drinking water, and food and beverages from existing monitoring databases or comprehensive literature reviews. Intake estimates were then multiplied by cancer potency factors from Health Canada, the United States Environmental Protection Agency, and the California Office of Environmental Health Hazard Assessment to estimate lifetime excess cancer risks associated with each substance and exposure pathway. Lifetime excess cancer risks in excess of 1 per million people are identified as potential priorities for further attention. RESULTS: Based on data representing average conditions circa 2006, a total of 18 carcinogen-exposure pathways had potential lifetime excess cancer risks greater than 1 per million, based on varying data quality. Carcinogens with moderate to high data quality and lifetime excess cancer risk greater than 1 per million included benzene, 1,3-butadiene and radon in outdoor air; benzene and radon in indoor air; and arsenic and hexavalent chromium in drinking water. Important data gaps were identified for asbestos, hexavalent chromium and diesel exhaust in outdoor and indoor air, while little data were available to assess risk for substances in dust, food and beverages. CONCLUSIONS: The ability to track changes in potential population exposures to environmental carcinogens over time, as well as to compare between different substances and exposure pathways, is necessary to support comprehensive, evidence-based prevention policy. We used estimates of lifetime excess cancer risk as indicators that, although based on a number of simplifying assumptions, help to identify important data gaps and prioritize more detailed data collection and exposure assessment needs."
1508572,Jennings 2013,Analysis of worldwide regulatory guidance values for the most commonly regulated elemental surface soil contamination,"Guidance values are used worldwide to regulate exposure to surface soil contamination. This analysis examines values applied to element contamination. In the United States, element guidance values have been promulgated by at least 6 federal agencies, 46 states and several regional, city, county, territorial, and autonomous Native American jurisdictions. Guidance values have also been promulgated in at least 71 other United Nations member states. A total of 5949 guidance values for 57 elements have been identified. These values are characterized, and detailed analyses are provided for the eight most frequently regulated elements (Pb, Cd, As, Ni, Cr, Hg, Cu, and Zn). More than 300 guidance values available for each of these are tabulated. These values span from 3.6 orders of magnitude for lead to 6.9 orders of magnitude for arsenic and are distributed in patterns that resemble those of lognormal random variables. However, nonrandom value clusters are also identified in each distribution. On average, the values used in the U.S. are higher than those used elsewhere around the world for noncarcinogenic contaminants, but are lower for carcinogenic contaminants. Approximately 31.4% of all values fall within uncertainty bounds computed from the U.S. Environmental Protection Agency cancer or noncancer risk model, but only 12.9% of carcinogenic arsenic and 7.5% of carcinogenic chromium (Cr-VI) guidance values fall within cancer risk model uncertainty bounds.","Analysis of worldwide regulatory guidance values for the most commonly regulated elemental surface soil contamination Abs: Guidance values are used worldwide to regulate exposure to surface soil contamination. This analysis examines values applied to element contamination. In the United States, element guidance values have been promulgated by at least 6 federal agencies, 46 states and several regional, city, county, territorial, and autonomous Native American jurisdictions. Guidance values have also been promulgated in at least 71 other United Nations member states. A total of 5949 guidance values for 57 elements have been identified. These values are characterized, and detailed analyses are provided for the eight most frequently regulated elements (Pb, Cd, As, Ni, Cr, Hg, Cu, and Zn). More than 300 guidance values available for each of these are tabulated. These values span from 3.6 orders of magnitude for lead to 6.9 orders of magnitude for arsenic and are distributed in patterns that resemble those of lognormal random variables. However, nonrandom value clusters are also identified in each distribution. On average, the values used in the U.S. are higher than those used elsewhere around the world for noncarcinogenic contaminants, but are lower for carcinogenic contaminants. Approximately 31.4% of all values fall within uncertainty bounds computed from the U.S. Environmental Protection Agency cancer or noncancer risk model, but only 12.9% of carcinogenic arsenic and 7.5% of carcinogenic chromium (Cr-VI) guidance values fall within cancer risk model uncertainty bounds."
1501174,Liverseed et al. 2013,Comparative Emissions of Random Orbital Sanding between Conventional and Self-Generated Vacuum Systems,"Conventional abrasive sanding generates high concentrations of particles. Depending on the substrate being abraded and exposure duration, overexposure to the particles can cause negative health effects ranging from respiratory irritation to cancer. The goal of this study was to understand the differences in particle emissions between a conventional random orbital sanding system and a self-generated vacuum random orbital sanding system with attached particle filtration bag. Particle concentrations were sampled for each system in a controlled test chamber for oak wood, chromate painted (hexavalent chromium) steel panels, and gel-coated (titanium dioxide) fiberglass panels using a Gesamtstaub-Probenahmesystem (GSP) sampler at three different locations adjacent to the sanding. Elevated concentrations were reported for all particles in the samples collected during conventional sanding. The geometric mean concentration ratios for the three substrates ranged from 320 to 4640 times greater for the conventional sanding system than the self-generated vacuum sanding system. The differences in the particle concentration generated by the two sanding systems were statistically significant with the two sample t-test (P &lt; 0.0001) for all three substances. The data suggest that workers using conventional sanding systems could utilize the self-generated vacuum sanding system technology to potentially reduce exposure to particles and mitigate negative health effects.","Comparative Emissions of Random Orbital Sanding between Conventional and Self-Generated Vacuum Systems Abs: Conventional abrasive sanding generates high concentrations of particles. Depending on the substrate being abraded and exposure duration, overexposure to the particles can cause negative health effects ranging from respiratory irritation to cancer. The goal of this study was to understand the differences in particle emissions between a conventional random orbital sanding system and a self-generated vacuum random orbital sanding system with attached particle filtration bag. Particle concentrations were sampled for each system in a controlled test chamber for oak wood, chromate painted (hexavalent chromium) steel panels, and gel-coated (titanium dioxide) fiberglass panels using a Gesamtstaub-Probenahmesystem (GSP) sampler at three different locations adjacent to the sanding. Elevated concentrations were reported for all particles in the samples collected during conventional sanding. The geometric mean concentration ratios for the three substrates ranged from 320 to 4640 times greater for the conventional sanding system than the self-generated vacuum sanding system. The differences in the particle concentration generated by the two sanding systems were statistically significant with the two sample t-test (P &lt; 0.0001) for all three substances. The data suggest that workers using conventional sanding systems could utilize the self-generated vacuum sanding system technology to potentially reduce exposure to particles and mitigate negative health effects."
1501099,Dozzi et al. 2012,Cr(VI) photocatalytic reduction: effects of simultaneous organics oxidation and of gold nanoparticles photodeposition on TiO2,"Commercial TiO(2) samples with different phase composition and surface area were tested as photocatalysts in the photoinduced reduction of Cr(VI) in aqueous suspensions at pH 3.7 under UV-visible light irradiation. This reaction was also coupled with the simultaneous photocatalytic oxidation of the pollutant azo dye Acid Orange 8 (AO8) and of formic acid, acting as hole scavengers. The co-presence of oxidizable and reducible species ensured better separation of photogenerated charge carriers, resulting in a higher rate of both organics' oxidation and Cr(VI) reduction, especially in the case of high surface area anatase TiO(2), having the strongest affinity for Cr(VI) and AO8, as demonstrated by competitive adsorption tests. The effects on Cr(VI) photocatalytic reduction of gold nanoparticles photodeposited on TiO(2) and of the Au loading were also investigated, aiming at ascertaining if this noble metal plays a role in the electron transfer processes involved in Cr(VI) reduction.","Cr(VI) photocatalytic reduction: effects of simultaneous organics oxidation and of gold nanoparticles photodeposition on TiO2 Abs: Commercial TiO(2) samples with different phase composition and surface area were tested as photocatalysts in the photoinduced reduction of Cr(VI) in aqueous suspensions at pH 3.7 under UV-visible light irradiation. This reaction was also coupled with the simultaneous photocatalytic oxidation of the pollutant azo dye Acid Orange 8 (AO8) and of formic acid, acting as hole scavengers. The co-presence of oxidizable and reducible species ensured better separation of photogenerated charge carriers, resulting in a higher rate of both organics' oxidation and Cr(VI) reduction, especially in the case of high surface area anatase TiO(2), having the strongest affinity for Cr(VI) and AO8, as demonstrated by competitive adsorption tests. The effects on Cr(VI) photocatalytic reduction of gold nanoparticles photodeposited on TiO(2) and of the Au loading were also investigated, aiming at ascertaining if this noble metal plays a role in the electron transfer processes involved in Cr(VI) reduction."
1499916,Prairie et al. 1993,An investigation of titanium dioxide photocatalysis for the treatment of water contaminated with metals and organic chemicals,"BIOSIS COPYRIGHT: BIOL ABS. Laboratory experiments were performed to investigate TiO2 photocatalysis for treating water contaminated with dissolved metals (Ag, Au, Cd, Cr, Cu, Hg, Ni, and Pt) and a variety of organics (e.g., methanol, formic acid, salicyclic acid, EDTA, phenol, and nitrobenzene). It was found that only those metals with half-reaction standard reduction potentials more positive than 0.3 V (vs normal hydrogen electrode) can be treated using TiO2 as the photocatalyst. Kinetic data illustrating the synergism between oxidation and reduction are presented. Experiments using singly substituted benzenes as electron donors show that the rate of reduction of Cr(VI) is correlated with Hammett sigma constants. Photoefficiencies approaching 85% were measured for the conversion of Cr(VI) to Cr(III) using citric acid as the reductant. In contrast, photoefficiency was only 4% when oxidizing salicyclic acid using O2 as the oxidant. It is concluded that efficient designs of photocatalytic systems f","An investigation of titanium dioxide photocatalysis for the treatment of water contaminated with metals and organic chemicals Abs: BIOSIS COPYRIGHT: BIOL ABS. Laboratory experiments were performed to investigate TiO2 photocatalysis for treating water contaminated with dissolved metals (Ag, Au, Cd, Cr, Cu, Hg, Ni, and Pt) and a variety of organics (e.g., methanol, formic acid, salicyclic acid, EDTA, phenol, and nitrobenzene). It was found that only those metals with half-reaction standard reduction potentials more positive than 0.3 V (vs normal hydrogen electrode) can be treated using TiO2 as the photocatalyst. Kinetic data illustrating the synergism between oxidation and reduction are presented. Experiments using singly substituted benzenes as electron donors show that the rate of reduction of Cr(VI) is correlated with Hammett sigma constants. Photoefficiencies approaching 85% were measured for the conversion of Cr(VI) to Cr(III) using citric acid as the reductant. In contrast, photoefficiency was only 4% when oxidizing salicyclic acid using O2 as the oxidant. It is concluded that efficient designs of photocatalytic systems f"
1499386,Wang et al. 2010,Visible light photocatalytic reduction of Cr(VI) on TiO2 in situ modified with small molecular weight organic acids,,Visible light photocatalytic reduction of Cr(VI) on TiO2 in situ modified with small molecular weight organic acids Abs: 
1499223,Tzou et al. 2004,Organic ligand-enhanced photochemical reduction and immobilization of chromium(VI) on TlO2 particles in acidic aqueous media,,Organic ligand-enhanced photochemical reduction and immobilization of chromium(VI) on TlO2 particles in acidic aqueous media Abs: 
1499193,Polprasert and  Liyanage L 1996,Hazardous waste generation and processing,"BIOSIS COPYRIGHT: BIOL ABS. A waste is considered hazardous if it exhibits one or more of the following characteristics: ignitability, corrosivity, reactivity and toxicity. This paper reviews the sources of hazardous waste generation which come mainly from industries. The major types of hazardous wastes are toxic organic compounds and heavy metals. Up to the present, the developed countries such as USA, Japan and many European countries are the major hazardous wastes generators, while increasing quantity of hazardous wastes is being generated by the newly industrialized countries (NICs). To minimize hazardous waste disposal problems, certain technologies to reduce waste quantity are recommended. These technologies include; in-plant minimization, raw material alteration, equipment redesign, improved housekeeping and product substitution. Some proven hazardous waste processing and treatment technologies are described in the paper.","Hazardous waste generation and processing Abs: BIOSIS COPYRIGHT: BIOL ABS. A waste is considered hazardous if it exhibits one or more of the following characteristics: ignitability, corrosivity, reactivity and toxicity. This paper reviews the sources of hazardous waste generation which come mainly from industries. The major types of hazardous wastes are toxic organic compounds and heavy metals. Up to the present, the developed countries such as USA, Japan and many European countries are the major hazardous wastes generators, while increasing quantity of hazardous wastes is being generated by the newly industrialized countries (NICs). To minimize hazardous waste disposal problems, certain technologies to reduce waste quantity are recommended. These technologies include; in-plant minimization, raw material alteration, equipment redesign, improved housekeeping and product substitution. Some proven hazardous waste processing and treatment technologies are described in the paper."
1499077,VO 1985,PROBLEMS OF HYGIENIC REGULATION OF THE USE OF POLYMER MATERIALS OUTSIDE THE USSR,BIOSIS COPYRIGHT: BIOL ABS. RRM REVIEW USA FOOD TOXICITY WATER POLLUTION,PROBLEMS OF HYGIENIC REGULATION OF THE USE OF POLYMER MATERIALS OUTSIDE THE USSR Abs: BIOSIS COPYRIGHT: BIOL ABS. RRM REVIEW USA FOOD TOXICITY WATER POLLUTION
1498860,Shim et al. 2008,Photocurrent by anodized TiO2 photoelectrode for enzymatic hydrogen production and chromium(VI) reduction,,Photocurrent by anodized TiO2 photoelectrode for enzymatic hydrogen production and chromium(VI) reduction Abs: 
1498513,Qamar et al. 2011,Synthesis of nanostructured NiO and its application in laser-induced photocatalytic reduction of Cr(VI) from water,,Synthesis of nanostructured NiO and its application in laser-induced photocatalytic reduction of Cr(VI) from water Abs: 
1497769,Lehmann et al. 1999,Removal of metal ions from dilute aqueous solutions: a comparative study of inorganic sorbent materials,"The removal of chromate anions and zinc cations, typical examples of toxic metals, from dilute aqueous solutions by sorption is described. Seven inorganic materials were tested for sorption properties powdered forms of magnesite mineral, consisting principally of magnesium carbonate; titanium dioxide; hydrotalcite; and geothite; and granulated forms of activated carbon; ferric hydroxide; and geothite. The removal of zinc in batch experiments increased as pH values increased and were quantitative at pH 8, 10, 4, 8 and 10 for ferric hydroxide, titanium dioxide, hydrotalcite, powdered geothite and crystallized geothite, respectively. The removal of chromium was below 50 per cent except for hydrotalcite, and powdered and crystallized geothite, where removal was 60-70 per cent at acidic pH values. Crystallized geothite was best suited for the removal of both cationic and anionic forms of metals when used in a fixed-bed operation.","Removal of metal ions from dilute aqueous solutions: a comparative study of inorganic sorbent materials Abs: The removal of chromate anions and zinc cations, typical examples of toxic metals, from dilute aqueous solutions by sorption is described. Seven inorganic materials were tested for sorption properties powdered forms of magnesite mineral, consisting principally of magnesium carbonate; titanium dioxide; hydrotalcite; and geothite; and granulated forms of activated carbon; ferric hydroxide; and geothite. The removal of zinc in batch experiments increased as pH values increased and were quantitative at pH 8, 10, 4, 8 and 10 for ferric hydroxide, titanium dioxide, hydrotalcite, powdered geothite and crystallized geothite, respectively. The removal of chromium was below 50 per cent except for hydrotalcite, and powdered and crystallized geothite, where removal was 60-70 per cent at acidic pH values. Crystallized geothite was best suited for the removal of both cationic and anionic forms of metals when used in a fixed-bed operation."
1495259,LA et al. 2000,Effect of Light on the Electrokinetic Behavior of TiO(2) Particles in Contact with Cr(VI) Aqueous Solutions,"The electrokinetic behavior of titanium dioxide particles (Degussa P25, mainly composed of anatase) put in contact with chromium(VI) aqueous solutions is highly sensitive to light exposure under normal laboratory conditions. In the dark, adsorption of Cr(VI) gives rise to substantial decrements in the mobilities, especially in the acidic branch, and, at higher concentrations, to shifts in the isoelectric point (pH(piep)) to lower values, as expected for anionic chemisorption. A two-mode adsorption model accounts qualitatively for the results. Under light, pH(piep) shifts in the opposite direction as the Cr(VI) concentration increases. A maximum value is attained at [Cr(VI)] approximately 10(-3) mol dm(-3), pH(piep) 8.2, which coincides with values reported for hydrous chromium(III) oxides. At higher concentrations, Cr(VI) adsorption defines a shift of pH(piep) to lower values. It is concluded that light absorption by titanium dioxide promotes the reduction of Cr(VI) and the surface precipitation of the hydrous Cr(III) oxide. The values of pH(piep) for partially covered surfaces are well described by a simple model of surface ionization derived earlier. FTIR/ATR analysis of the surfaces supports this interpretation, and further suggests that one of the modes of Cr(VI) adsorption implies surface dimerization to yield adsorbed dichromate. Copyright 2000 Academic Press.","Effect of Light on the Electrokinetic Behavior of TiO(2) Particles in Contact with Cr(VI) Aqueous Solutions Abs: The electrokinetic behavior of titanium dioxide particles (Degussa P25, mainly composed of anatase) put in contact with chromium(VI) aqueous solutions is highly sensitive to light exposure under normal laboratory conditions. In the dark, adsorption of Cr(VI) gives rise to substantial decrements in the mobilities, especially in the acidic branch, and, at higher concentrations, to shifts in the isoelectric point (pH(piep)) to lower values, as expected for anionic chemisorption. A two-mode adsorption model accounts qualitatively for the results. Under light, pH(piep) shifts in the opposite direction as the Cr(VI) concentration increases. A maximum value is attained at [Cr(VI)] approximately 10(-3) mol dm(-3), pH(piep) 8.2, which coincides with values reported for hydrous chromium(III) oxides. At higher concentrations, Cr(VI) adsorption defines a shift of pH(piep) to lower values. It is concluded that light absorption by titanium dioxide promotes the reduction of Cr(VI) and the surface precipitation of the hydrous Cr(III) oxide. The values of pH(piep) for partially covered surfaces are well described by a simple model of surface ionization derived earlier. FTIR/ATR analysis of the surfaces supports this interpretation, and further suggests that one of the modes of Cr(VI) adsorption implies surface dimerization to yield adsorbed dichromate. Copyright 2000 Academic Press."
1493720,Wang et al. 2008,Photocatalytic reduction of Cr(VI) over different TiO2 photocatalysts and the effects of dissolved organic species,"The toxic Cr(VI) in industrial wastewaters can be removed by a reduction from Cr(VI) to Cr(III) and a followed precipitation treatment. The reduction of Cr(VI) to Cr(III) is able to be achieved by a photocatalytic process. Thus, photocatalytic reduction of Cr(VI) over TiO2 catalysts was investigated in both the absence and presence of organic compounds. The TiO(2) catalyst was pre-calcined at different temperatures to tune the photocatalytic activity and surface area of the photocatalyst. Under the tested conditions, the photocatalytic reduction of Cr(VI) behaved as a pseudo-first-order reaction in kinetics. In the absence of any organic species, the rate constant (kCr) for the photocatalytic reduction of Cr(VI) was found to be increased initially, passing a maximum, and then decreased, as calcination temperature was increased. In the presence of organic compounds, however, kCr was decreased with the increase of calcination temperature. A marked synergistic effect between the photocatalytic reduction of Cr(VI) and organic compounds was observed over the photocatalyst with the largest specific surface area. These results demonstrated that the photocatalytic reduction of Cr(VI) alone was dependent on both of specific surface area and crystalline structure of the photocatalyst in the absence of any organic compounds, but was dominated by the specific surface area of the photocatalyst in the presence of organic compounds because of the synergistic effect between the photocatalytic reduction of Cr(IV) and the photocatalytic oxidation of organic compounds.","Photocatalytic reduction of Cr(VI) over different TiO2 photocatalysts and the effects of dissolved organic species Abs: The toxic Cr(VI) in industrial wastewaters can be removed by a reduction from Cr(VI) to Cr(III) and a followed precipitation treatment. The reduction of Cr(VI) to Cr(III) is able to be achieved by a photocatalytic process. Thus, photocatalytic reduction of Cr(VI) over TiO2 catalysts was investigated in both the absence and presence of organic compounds. The TiO(2) catalyst was pre-calcined at different temperatures to tune the photocatalytic activity and surface area of the photocatalyst. Under the tested conditions, the photocatalytic reduction of Cr(VI) behaved as a pseudo-first-order reaction in kinetics. In the absence of any organic species, the rate constant (kCr) for the photocatalytic reduction of Cr(VI) was found to be increased initially, passing a maximum, and then decreased, as calcination temperature was increased. In the presence of organic compounds, however, kCr was decreased with the increase of calcination temperature. A marked synergistic effect between the photocatalytic reduction of Cr(VI) and organic compounds was observed over the photocatalyst with the largest specific surface area. These results demonstrated that the photocatalytic reduction of Cr(VI) alone was dependent on both of specific surface area and crystalline structure of the photocatalyst in the absence of any organic compounds, but was dominated by the specific surface area of the photocatalyst in the presence of organic compounds because of the synergistic effect between the photocatalytic reduction of Cr(IV) and the photocatalytic oxidation of organic compounds."
1490462,Lin et al. 2009,Structure and thermal stability of toxic chromium(VI) species doped onto TiO(2) powders through heat treatment,"Chromium(VI)-containing sorbents in the form of sludge or solid residue from treatment processes are often landfilled or used as fill materials, therefore the long-term stability of metal binding is important. The reduction of Cr(VI)-Cr(III) through heat treatment may be a useful detoxification method. After heating at 500, 900, 1000, and 1100 degrees C for 4h, the transformation of chemical states of chromium on 105 degrees C-dried, 7.9% Cr(VI)-doped TiO(2) powders was studied on the basis of surface area measurements, scanning electron microscopy (SEM) images, X-ray diffraction (XRD), and extended X-ray absorption fine structure (EXAFS) spectra. It was shown that Cr(VI) was reduced to Cr(III) in the Cr(VI)-doped samples after heating within 500-900 degrees C. The present results also suggested that the chromium octahedral was bridged to the titanium tetrahedral and was incorporated in TiO(2) minerals formed after 1000 degrees C treatment.","Structure and thermal stability of toxic chromium(VI) species doped onto TiO(2) powders through heat treatment Abs: Chromium(VI)-containing sorbents in the form of sludge or solid residue from treatment processes are often landfilled or used as fill materials, therefore the long-term stability of metal binding is important. The reduction of Cr(VI)-Cr(III) through heat treatment may be a useful detoxification method. After heating at 500, 900, 1000, and 1100 degrees C for 4h, the transformation of chemical states of chromium on 105 degrees C-dried, 7.9% Cr(VI)-doped TiO(2) powders was studied on the basis of surface area measurements, scanning electron microscopy (SEM) images, X-ray diffraction (XRD), and extended X-ray absorption fine structure (EXAFS) spectra. It was shown that Cr(VI) was reduced to Cr(III) in the Cr(VI)-doped samples after heating within 500-900 degrees C. The present results also suggested that the chromium octahedral was bridged to the titanium tetrahedral and was incorporated in TiO(2) minerals formed after 1000 degrees C treatment."
1490456,Paschoal et al. 2009,Simultaneous removal of chromium and leather dye from simulated tannery effluent by photoelectrochemistry,"The feasibility of the photobleaching of a leather acid dye, acid red 151, simultaneously to degradation of anionic surfactant, Tamol, and reduction of Cr(VI) to the less toxic Cr(III) was investigated by photoelectrocatalytic oxidation. The best experimental conditions were found to be pH 2.0 and 0.1 mol L(-1) sodium sulfate when the nanoporous Ti/TiO2 photo anode was biased at +1.0 V and submitted to UV-irradiation. The photoelectrocatalytic oxidation promotes 100% discoloration, reducing around 98-100% of Cr(VI) and achieving an abatement of 95% of the original total organic carbon. The effect of pH, the applied potential, the Cr(VI) concentration and the complexation reaction between Cr(VI) and acid red dye were evaluated as to their effect on the kinetics of the reaction.","Simultaneous removal of chromium and leather dye from simulated tannery effluent by photoelectrochemistry Abs: The feasibility of the photobleaching of a leather acid dye, acid red 151, simultaneously to degradation of anionic surfactant, Tamol, and reduction of Cr(VI) to the less toxic Cr(III) was investigated by photoelectrocatalytic oxidation. The best experimental conditions were found to be pH 2.0 and 0.1 mol L(-1) sodium sulfate when the nanoporous Ti/TiO2 photo anode was biased at +1.0 V and submitted to UV-irradiation. The photoelectrocatalytic oxidation promotes 100% discoloration, reducing around 98-100% of Cr(VI) and achieving an abatement of 95% of the original total organic carbon. The effect of pH, the applied potential, the Cr(VI) concentration and the complexation reaction between Cr(VI) and acid red dye were evaluated as to their effect on the kinetics of the reaction."
1487233,Varshney 1998,FATE AND EXPOSURE MODELS SELECTING THE APPROPRIATE MODEL FOR YOUR APPLICATION A COMMENTARY ON API'S DSS,BIOSIS COPYRIGHT: BIOL ABS. RRM RESEARCH ARTICLE POLLUTION SOIL SCIENCE MODELS AND SIMULATIONS DSS MODEL API AMERICAN PETROLEUM INSTITUTE PETROLEUM HYDROCARBONS POLLUTANT FATE AND EXPOSURE MODEL,FATE AND EXPOSURE MODELS SELECTING THE APPROPRIATE MODEL FOR YOUR APPLICATION A COMMENTARY ON API'S DSS Abs: BIOSIS COPYRIGHT: BIOL ABS. RRM RESEARCH ARTICLE POLLUTION SOIL SCIENCE MODELS AND SIMULATIONS DSS MODEL API AMERICAN PETROLEUM INSTITUTE PETROLEUM HYDROCARBONS POLLUTANT FATE AND EXPOSURE MODEL
1487175,Brandelli et al. 1992,TOXICITY IDENTIFICATION AND REDUCTION EVALUATION IN PETROCHEMICAL EFFLUENTS SITEL CASE,BIOSIS COPYRIGHT: BIOL ABS. RRM PIMEPHALES-PROMELAS FISH DAPHNIA-SIMILIS INVERTEBRATE PETROLEUM INDUSTRY WATER POLLUTION CONTROL WASTEWATER TREATMENT SOURCE IDENTIFICATION INTEGRATED WASTEWATER SYSTEM OF SOUTH PETROCHEMICAL COMPLEX EPA USA,TOXICITY IDENTIFICATION AND REDUCTION EVALUATION IN PETROCHEMICAL EFFLUENTS SITEL CASE Abs: BIOSIS COPYRIGHT: BIOL ABS. RRM PIMEPHALES-PROMELAS FISH DAPHNIA-SIMILIS INVERTEBRATE PETROLEUM INDUSTRY WATER POLLUTION CONTROL WASTEWATER TREATMENT SOURCE IDENTIFICATION INTEGRATED WASTEWATER SYSTEM OF SOUTH PETROCHEMICAL COMPLEX EPA USA
1486648,Subramanian and  Uma 1996,CYANOBACTERIA IN POLLUTION CONTROL,BIOSIS COPYRIGHT: BIOL ABS. RRM LITERATURE REVIEW CYANOBACTERIA POLLUTION METABOLISM MICROBIOLOGY POLLUTION CONTROL BIOREMEDIATION TOXIC COMPOUND DEGRADATION TEMPERATURE-PH EFFECTS,CYANOBACTERIA IN POLLUTION CONTROL Abs: BIOSIS COPYRIGHT: BIOL ABS. RRM LITERATURE REVIEW CYANOBACTERIA POLLUTION METABOLISM MICROBIOLOGY POLLUTION CONTROL BIOREMEDIATION TOXIC COMPOUND DEGRADATION TEMPERATURE-PH EFFECTS
1483177,Kim 1993,INDUSTRIAL WASTES AUTOMOTIVE WASTES,BIOSIS COPYRIGHT: BIOL ABS. RRM REVIEW WASTE MANAGEMENT AUTOMOBILE INDUSTRY POLLUTION CONTROL LIFE-CYCLE COST METALS PAINT VOLATILE ORGANIC COMPOUNDS,INDUSTRIAL WASTES AUTOMOTIVE WASTES Abs: BIOSIS COPYRIGHT: BIOL ABS. RRM REVIEW WASTE MANAGEMENT AUTOMOBILE INDUSTRY POLLUTION CONTROL LIFE-CYCLE COST METALS PAINT VOLATILE ORGANIC COMPOUNDS
1482893,Wiles et al. 1988,STATUS OF SOLIDIFICATION-STABILIZATION IN THE USA AND FACTORS AFFECTING ITS USE,BIOSIS COPYRIGHT: BIOL ABS. RRM WASTE MANAGEMENT ENVIRONMENTAL POLLUTANT EPA,STATUS OF SOLIDIFICATION-STABILIZATION IN THE USA AND FACTORS AFFECTING ITS USE Abs: BIOSIS COPYRIGHT: BIOL ABS. RRM WASTE MANAGEMENT ENVIRONMENTAL POLLUTANT EPA
1482423,Ward 1988,WORKSHOP ON TECHNIQUES FOR CULTURING MARINE ALGAE AND INVERTEBRATES FOR USE IN TOXICITY TESTS HELD AT THE SEVENTH ANNUAL MEETING OF THE SOCIETY OF ENVIRONMENTAL TOXICOLOGY AND CHEMISTRY ALEXANDRIA VIRGINIA USA NOVEMBER 2-5 1986,BIOSIS COPYRIGHT: BIOL ABS. RRM ANIMALS PLANTS TOXICITY TEST ORGANISM ESTUARY SOIL POLLUTION WATER POLLUTION CONTAMINATION,WORKSHOP ON TECHNIQUES FOR CULTURING MARINE ALGAE AND INVERTEBRATES FOR USE IN TOXICITY TESTS HELD AT THE SEVENTH ANNUAL MEETING OF THE SOCIETY OF ENVIRONMENTAL TOXICOLOGY AND CHEMISTRY ALEXANDRIA VIRGINIA USA NOVEMBER 2-5 1986 Abs: BIOSIS COPYRIGHT: BIOL ABS. RRM ANIMALS PLANTS TOXICITY TEST ORGANISM ESTUARY SOIL POLLUTION WATER POLLUTION CONTAMINATION
1481747,Radian Corp 1991,"AIR TOXIC ""HOT SPOTS"" - AB 2588 HEALTH RISK ASSESSMENT DOUGLAS AIRCRAFT COMPANY LONG BEACH FACILITY VOLUME I WITH COVER LETTER DATED 081291",,"AIR TOXIC ""HOT SPOTS"" - AB 2588 HEALTH RISK ASSESSMENT DOUGLAS AIRCRAFT COMPANY LONG BEACH FACILITY VOLUME I WITH COVER LETTER DATED 081291 Abs: "
1468132,Nagaraj et al. 2009,Spectrophotometric method for the determination of chromium (VI) in water samples,"A simple and sensitive spectrophotometric method for the determination of chromium has been developed. The method is based on the diazotization of Dapsone in hydroxylamine hydrochloride medium and coupling with N-(1-Napthyl) Ethylene Diamine Dihydrochloride by electrophilic substitution to produce an intense pink azo-dye, which has absorption maximum at 540 nm. The Beer's law is obeyed from 0.02-1.0 microg mL(-1) and the molar absorptivity is 3.4854 L mol(-1) cm(-1). The Limits of quantification and Limit of detection of the proposed method are 0.0012 microg mL(-1) and 0.0039 microg mL(-1) respectively. The method has been successfully applied for the determination of chromium in water samples and the results were statistically evaluated with that of the reference method.","Spectrophotometric method for the determination of chromium (VI) in water samples Abs: A simple and sensitive spectrophotometric method for the determination of chromium has been developed. The method is based on the diazotization of Dapsone in hydroxylamine hydrochloride medium and coupling with N-(1-Napthyl) Ethylene Diamine Dihydrochloride by electrophilic substitution to produce an intense pink azo-dye, which has absorption maximum at 540 nm. The Beer's law is obeyed from 0.02-1.0 microg mL(-1) and the molar absorptivity is 3.4854 L mol(-1) cm(-1). The Limits of quantification and Limit of detection of the proposed method are 0.0012 microg mL(-1) and 0.0039 microg mL(-1) respectively. The method has been successfully applied for the determination of chromium in water samples and the results were statistically evaluated with that of the reference method."
1468093,Gopi Krishna et al. 2004,Preconcentrative separation of chromium(VI) species from chromium(III) by coprecipitation of its ethyl xanthate complex onto naphthalene,"A rapid, sensitive and selective method is described for the determination of chromium(VI) in presence of 100-fold amounts of chromium(III) by flame atomic absorption spectrometry (FAAS) in conjunction with coprecipitative preconcentration of its ethyl xanthate complex onto naphthalene. The solid mixture consisting of the chromium(VI) complex together with naphthalene is dissolved in 8.0ml of dimethyl formamide (DMF) and chromium(VI) content was established by FAAS. Calibration graphs were rectilinear over the chromium(VI) concentration in the range 0-200mugl(-1). Five replicate determinations of 20mug of chromium(VI) present in 1.0l of sample solution gave a relative standard deviation of 3.1%. The detection limit corresponding to three times the standard deviation of the blank was found to be 0.5mugl(-1). The developed procedure has been successfully utilized for the estimation of chromium(VI), chromium(total) (after oxidation with bromate) and chromium(III) (by subtracting chromium(VI) content from chromium(total) value contents of several tannery industries.","Preconcentrative separation of chromium(VI) species from chromium(III) by coprecipitation of its ethyl xanthate complex onto naphthalene Abs: A rapid, sensitive and selective method is described for the determination of chromium(VI) in presence of 100-fold amounts of chromium(III) by flame atomic absorption spectrometry (FAAS) in conjunction with coprecipitative preconcentration of its ethyl xanthate complex onto naphthalene. The solid mixture consisting of the chromium(VI) complex together with naphthalene is dissolved in 8.0ml of dimethyl formamide (DMF) and chromium(VI) content was established by FAAS. Calibration graphs were rectilinear over the chromium(VI) concentration in the range 0-200mugl(-1). Five replicate determinations of 20mug of chromium(VI) present in 1.0l of sample solution gave a relative standard deviation of 3.1%. The detection limit corresponding to three times the standard deviation of the blank was found to be 0.5mugl(-1). The developed procedure has been successfully utilized for the estimation of chromium(VI), chromium(total) (after oxidation with bromate) and chromium(III) (by subtracting chromium(VI) content from chromium(total) value contents of several tannery industries."
1466105,Elfant and  Keen 1987,Sodium vanadate toxicity in adult and developing rats,"The toxic effect of vanadium (sodium metavanadate) during pregnancy and lactation was studied by feeding vanadium to pregnant, Sprague-Dawley rats at levels of 1 (control) or 75 ?g V/g diet through d 21 postpartum, at which time they were killed. Vanadium-fed dams had lower food intakes and weight gains than controls during pregnancy. Survival until d 21 postpartum was significantly lower in the vanadium pups compared to controls. In addition, the surviving pups gained less weight than control pups, despite similar birth weights. On a relative body weight basis, vanadium pups had larger livers, brains, and testes than controls, suggesting that these animals were developmentally delayed. Vanadium dams and pups had higher concentrations of hepatic vanadium than controls. Vanadium pups also had higher concentrations of hepatic zinc than control pups. Maternal hepatic zinc concentrations were not affected by diet. Also, no significant differences in hepatic iron, copper, or manganese concentrations were observed for either dams or pups. Hepatic thiobarbituric acid reactivity was higher in whole cell and isolated mitochondria for vanadium dams and pups than for control dams and pups, indicating that these animals may have had higher levels of lipid peroxidation. This idea was supported by the observation of lower concentrations of reduced glutathione in the livers of vanadium pups compared to controls. In contrast, kidney and brain glutathione levels were not affected by diet. In conclusion, animals during periods of rapid growth are susceptible to vanadium toxicity, and increased lipid peroxidation may be one factor underlying this toxicity.","Sodium vanadate toxicity in adult and developing rats Abs: The toxic effect of vanadium (sodium metavanadate) during pregnancy and lactation was studied by feeding vanadium to pregnant, Sprague-Dawley rats at levels of 1 (control) or 75 ?g V/g diet through d 21 postpartum, at which time they were killed. Vanadium-fed dams had lower food intakes and weight gains than controls during pregnancy. Survival until d 21 postpartum was significantly lower in the vanadium pups compared to controls. In addition, the surviving pups gained less weight than control pups, despite similar birth weights. On a relative body weight basis, vanadium pups had larger livers, brains, and testes than controls, suggesting that these animals were developmentally delayed. Vanadium dams and pups had higher concentrations of hepatic vanadium than controls. Vanadium pups also had higher concentrations of hepatic zinc than control pups. Maternal hepatic zinc concentrations were not affected by diet. Also, no significant differences in hepatic iron, copper, or manganese concentrations were observed for either dams or pups. Hepatic thiobarbituric acid reactivity was higher in whole cell and isolated mitochondria for vanadium dams and pups than for control dams and pups, indicating that these animals may have had higher levels of lipid peroxidation. This idea was supported by the observation of lower concentrations of reduced glutathione in the livers of vanadium pups compared to controls. In contrast, kidney and brain glutathione levels were not affected by diet. In conclusion, animals during periods of rapid growth are susceptible to vanadium toxicity, and increased lipid peroxidation may be one factor underlying this toxicity."
1449511,Halasova et al. 2012,Evaluating chromosomal damage in workers exposed to hexavalent chromium and the modulating role of polymorphisms of DNA repair genes,"Welders have been chronically exposed to hexavalent chromium with potential consequences on chromosomal integrity. Our study is focused on the extent of any such chromosomal aberrations with respect to chromium levels in the blood of welders as well as on the tentative modulating role of polymorphisms in DNA repair genes XPD Lys751Gln, XPG Asn114His, XPC Lys939Gln, hOGG1 Ser326Cys and XRCC1 Arg399Gln on chromosomal damage. The study was conducted on 144 individuals consisting of 73 welders exposed to chromium for 10.2 ± 1.67 years and 71 control individuals without known exposures. Chromosomal aberrations, their chromatid-type and chromosome-type aberrations were detected by conventional cytogenetic analysis. XPD, XPG, XPC, hOGG1 and XRCC1 gene polymorphisms were assayed for by Taqman SNP genotyping assay (""Assay-by-Demand"") using Real-Time allelic discrimination on AB 7500 equipment. Chromium concentration in the blood was determined by atomic absorption spectrophotometry. The level of chromium in the blood of welders ranged between 0.032 and 0.182 ?mol l^sup -1^ and was significantly higher than that in controls (0.07 ± 0.04 ?mol l^sup -1^ vs. 0.03 ± 0.007 ?mol l^sup -1^). Parameters of chromosomal damage were similar in both the exposed and the control individuals (1.89% vs. 1.70% for total chromosomal aberrations, 0.97% vs. 0.88% for chromosome-type and 0.92% vs. 0.80% for chromatid-type, respectively). Chromatid-type of aberrations positively correlated with the level of chromium in the blood (r = 0.28; P = 0.02). Significantly higher total chromosomal aberrations were detected in individuals with homozygous variant polymorphism in XRCC1 Arg399Gln gene as compared to those with heterozygous and homozygous wild-type genotypes (2.20, 1.89 and 1.48%, respectively; P = 0.01). A similar tendency was found for chromatid-type aberrations (1.30% for homozygous variant genotype bearers, 0.94% for those with heterozygous genotype and 0.75% for carriers of homozygous wild-type genotype, respectively; P = 0.04). Although no apparent increase in chromosomal damage was recorded in chromium-exposed welders in comparison with controls, genetic make-up in DNA repair genes may increase susceptibility toward adverse effect of chromium.[PUBLICATION ABSTRACT] Welders have been chronically exposed to hexavalent chromium with potential consequences on chromosomal integrity. Our study is focused on the extent of any such chromosomal aberrations with respect to chromium levels in the blood of welders as well as on the tentative modulating role of polymorphisms in DNA repair genes XPD Lys751Gln, XPG Asn114His, XPC Lys939Gln, hOGG1 Ser326Cys and XRCC1 Arg399Gln on chromosomal damage. The study was conducted on 144 individuals consisting of 73 welders exposed to chromium for 10.2 ± 1.67 years and 71 control individuals without known exposures. Chromosomal aberrations, their chromatid-type and chromosome-type aberrations were detected by conventional cytogenetic analysis. XPD, XPG, XPC, hOGG1 and XRCC1 gene polymorphisms were assayed for by Taqman SNP genotyping assay (""Assay-by-Demand"") using Real-Time allelic discrimination on AB 7500 equipment. Chromium concentration in the blood was determined by atomic absorption spectrophotometry. The level of chromium in the blood of welders ranged between 0.032 and 0.182 ?mol l(-1) and was significantly higher than that in controls (0.07 ± 0.04 ?mol l(-1) vs. 0.03 ± 0.007 ?mol l(-1)). Parameters of chromosomal damage were similar in both the exposed and the control individuals (1.89% vs. 1.70% for total chromosomal aberrations, 0.97% vs. 0.88% for chromosome-type and 0.92% vs. 0.80% for chromatid-type, respectively). Chromatid-type of aberrations positively correlated with the level of chromium in the blood (r = 0.28; P = 0.02). Significantly higher total chromosomal aberrations were d tected in individuals with homozygous variant polymorphism in XRCC1 Arg399Gln gene as compared to those with heterozygous and homozygous wild-type genotypes (2.20, 1.89 and 1.48%, respectively; P = 0.01). A similar tendency was found for chromatid-type aberrations (1.30% for homozygous variant genotype bearers, 0.94% for those with heterozygous genotype and 0.75% for carriers of homozygous wild-type genotype, respectively; P = 0.04). Although no apparent increase in chromosomal damage was recorded in chromium-exposed welders in comparison with controls, genetic make-up in DNA repair genes may increase susceptibility toward adverse effect of chromium.","Evaluating chromosomal damage in workers exposed to hexavalent chromium and the modulating role of polymorphisms of DNA repair genes Abs: Welders have been chronically exposed to hexavalent chromium with potential consequences on chromosomal integrity. Our study is focused on the extent of any such chromosomal aberrations with respect to chromium levels in the blood of welders as well as on the tentative modulating role of polymorphisms in DNA repair genes XPD Lys751Gln, XPG Asn114His, XPC Lys939Gln, hOGG1 Ser326Cys and XRCC1 Arg399Gln on chromosomal damage. The study was conducted on 144 individuals consisting of 73 welders exposed to chromium for 10.2 ± 1.67 years and 71 control individuals without known exposures. Chromosomal aberrations, their chromatid-type and chromosome-type aberrations were detected by conventional cytogenetic analysis. XPD, XPG, XPC, hOGG1 and XRCC1 gene polymorphisms were assayed for by Taqman SNP genotyping assay (""Assay-by-Demand"") using Real-Time allelic discrimination on AB 7500 equipment. Chromium concentration in the blood was determined by atomic absorption spectrophotometry. The level of chromium in the blood of welders ranged between 0.032 and 0.182 ?mol l^sup -1^ and was significantly higher than that in controls (0.07 ± 0.04 ?mol l^sup -1^ vs. 0.03 ± 0.007 ?mol l^sup -1^). Parameters of chromosomal damage were similar in both the exposed and the control individuals (1.89% vs. 1.70% for total chromosomal aberrations, 0.97% vs. 0.88% for chromosome-type and 0.92% vs. 0.80% for chromatid-type, respectively). Chromatid-type of aberrations positively correlated with the level of chromium in the blood (r = 0.28; P = 0.02). Significantly higher total chromosomal aberrations were detected in individuals with homozygous variant polymorphism in XRCC1 Arg399Gln gene as compared to those with heterozygous and homozygous wild-type genotypes (2.20, 1.89 and 1.48%, respectively; P = 0.01). A similar tendency was found for chromatid-type aberrations (1.30% for homozygous variant genotype bearers, 0.94% for those with heterozygous genotype and 0.75% for carriers of homozygous wild-type genotype, respectively; P = 0.04). Although no apparent increase in chromosomal damage was recorded in chromium-exposed welders in comparison with controls, genetic make-up in DNA repair genes may increase susceptibility toward adverse effect of chromium.[PUBLICATION ABSTRACT] Welders have been chronically exposed to hexavalent chromium with potential consequences on chromosomal integrity. Our study is focused on the extent of any such chromosomal aberrations with respect to chromium levels in the blood of welders as well as on the tentative modulating role of polymorphisms in DNA repair genes XPD Lys751Gln, XPG Asn114His, XPC Lys939Gln, hOGG1 Ser326Cys and XRCC1 Arg399Gln on chromosomal damage. The study was conducted on 144 individuals consisting of 73 welders exposed to chromium for 10.2 ± 1.67 years and 71 control individuals without known exposures. Chromosomal aberrations, their chromatid-type and chromosome-type aberrations were detected by conventional cytogenetic analysis. XPD, XPG, XPC, hOGG1 and XRCC1 gene polymorphisms were assayed for by Taqman SNP genotyping assay (""Assay-by-Demand"") using Real-Time allelic discrimination on AB 7500 equipment. Chromium concentration in the blood was determined by atomic absorption spectrophotometry. The level of chromium in the blood of welders ranged between 0.032 and 0.182 ?mol l(-1) and was significantly higher than that in controls (0.07 ± 0.04 ?mol l(-1) vs. 0.03 ± 0.007 ?mol l(-1)). Parameters of chromosomal damage were similar in both the exposed and the control individuals (1.89% vs. 1.70% for total chromosomal aberrations, 0.97% vs. 0.88% for chromosome-type and 0.92% vs. 0.80% for chromatid-type, respectively). Chromatid-type of aberrations positively correlated with the level of chromium in the blood (r = 0.28; P = 0.02). Significantly higher total chromosomal aberrations were d tected in individuals with homozygous variant polymorphism in XRCC1 Arg399Gln gene as compared to those with heterozygous and homozygous wild-type genotypes (2.20, 1.89 and 1.48%, respectively; P = 0.01). A similar tendency was found for chromatid-type aberrations (1.30% for homozygous variant genotype bearers, 0.94% for those with heterozygous genotype and 0.75% for carriers of homozygous wild-type genotype, respectively; P = 0.04). Although no apparent increase in chromosomal damage was recorded in chromium-exposed welders in comparison with controls, genetic make-up in DNA repair genes may increase susceptibility toward adverse effect of chromium."
1448986,Potgieter-Vermaak et al. 2012,Component-specific toxic concerns of the inhalable fraction of urban road dust,"Continuous global urbanisation causes an ever-growing ecological footprint of pollution. Road dust (RD), one of these pollutants, poses a health concern due to carcinogenic and toxic components potentially present in the micron-sized fractions. The literature reports on the concentrations of trace, toxic metals and metalloids present in RD (Hooker and Nathanail in Chem Geol 226:340-351, 2006), but the literature on its molecular composition is limited. Recent reports on the bioaccessibility of platinum group metals are also reported (Colombo et al. in Chem Geol 226:340-351, 2008). In vitro and animal toxicological studies confirmed that the chemical composition of inhaled particles plays a major role in its toxic, genotoxic and carcinogenic mechanisms, but the component-specific toxic effects are still not understood. Particle-bound airborne transition metals can also lead to the production of reactive oxygen species in lung tissue; a special concern amongst particularly susceptible cohorts (children and elderly). The characterisation of the molecular composition of the fine fraction is evidently of importance for public health. During a pilot study, partially characterised size-fractioned RD samples (Barrett et al. in Eviron Sci Technol 44:2940-2946, 2010) were analysed for their elemental concentration using X-ray fluorescence spectrometry and inductively coupled plasma mass spectrometry. In addition, separately dispersed particles (200 particles per size fraction) were analysed individually by means of computer-controlled electron probe X-ray micro-analysis (CC-EPXMA) and their molecular structure probed by studying elemental associations. These were correlated with micro-Raman spectroscopy (MRS) results. It was found that the fine fraction (&lt;38 ?m) had the highest Pb (238 ppm) and Cr (171 ppm) concentrations. The CC-EPXMA data showed &gt;50 % association of Cr-rich particles with Pb, and the MRS data showed that the Cr was mostly present as lead chromate and therefore in the Cr(VI) oxidation state. Concentrations of both Pb and Cr decreased substantially (279 (&lt;38 ?m)-13 ppm (&lt;1 mm); 171 (&lt;38 ?m)-91 ppm (&lt; 1 mm), respectively) in the larger fractions. Apart from rather alarmingly high concentrations of oxidative stressors (Cu, Fe, Mn), the carcinogenic and toxic potential of the inhalable fraction is evident. Preliminary bioaccessibility data indicated that both Cr and Pb are readily mobilised in artificial lysosomal liquid and up to 19 % of Cr and 47 % of Pb were released.","Component-specific toxic concerns of the inhalable fraction of urban road dust Abs: Continuous global urbanisation causes an ever-growing ecological footprint of pollution. Road dust (RD), one of these pollutants, poses a health concern due to carcinogenic and toxic components potentially present in the micron-sized fractions. The literature reports on the concentrations of trace, toxic metals and metalloids present in RD (Hooker and Nathanail in Chem Geol 226:340-351, 2006), but the literature on its molecular composition is limited. Recent reports on the bioaccessibility of platinum group metals are also reported (Colombo et al. in Chem Geol 226:340-351, 2008). In vitro and animal toxicological studies confirmed that the chemical composition of inhaled particles plays a major role in its toxic, genotoxic and carcinogenic mechanisms, but the component-specific toxic effects are still not understood. Particle-bound airborne transition metals can also lead to the production of reactive oxygen species in lung tissue; a special concern amongst particularly susceptible cohorts (children and elderly). The characterisation of the molecular composition of the fine fraction is evidently of importance for public health. During a pilot study, partially characterised size-fractioned RD samples (Barrett et al. in Eviron Sci Technol 44:2940-2946, 2010) were analysed for their elemental concentration using X-ray fluorescence spectrometry and inductively coupled plasma mass spectrometry. In addition, separately dispersed particles (200 particles per size fraction) were analysed individually by means of computer-controlled electron probe X-ray micro-analysis (CC-EPXMA) and their molecular structure probed by studying elemental associations. These were correlated with micro-Raman spectroscopy (MRS) results. It was found that the fine fraction (&lt;38 ?m) had the highest Pb (238 ppm) and Cr (171 ppm) concentrations. The CC-EPXMA data showed &gt;50 % association of Cr-rich particles with Pb, and the MRS data showed that the Cr was mostly present as lead chromate and therefore in the Cr(VI) oxidation state. Concentrations of both Pb and Cr decreased substantially (279 (&lt;38 ?m)-13 ppm (&lt;1 mm); 171 (&lt;38 ?m)-91 ppm (&lt; 1 mm), respectively) in the larger fractions. Apart from rather alarmingly high concentrations of oxidative stressors (Cu, Fe, Mn), the carcinogenic and toxic potential of the inhalable fraction is evident. Preliminary bioaccessibility data indicated that both Cr and Pb are readily mobilised in artificial lysosomal liquid and up to 19 % of Cr and 47 % of Pb were released."
1448529,Italiano et al. 2012,"Changes in morphology, cell wall composition and soluble proteome in Rhodobacter sphaeroides cells exposed to chromate","The response of the carotenoidless Rhodobacter sphaeroides mutant R26 to chromate stress under photosynthetic conditions is investigated by biochemical and spectroscopic measurements, proteomic analysis and cell imaging. Cell cultures were found able to reduce chromate within 3-4 days. Chromate induces marked changes in the cellular dimension and morphology, as revealed by atomic force microscopy, along with compositional changes in the cell wall revealed by infrared spectroscopy. These effects are accompanied by significant changes in the level of several proteins: 15 proteins were found up-regulated and 15 down-regulated. The protein content found in chromate exposed cells is in good agreement with the biochemical, spectroscopic and microscopic results. Moreover at the present stage no specific chromate-reductase could be found in the soluble proteome, indicating that detoxification of the pollutant proceeds via aspecific reductants.","Changes in morphology, cell wall composition and soluble proteome in Rhodobacter sphaeroides cells exposed to chromate Abs: The response of the carotenoidless Rhodobacter sphaeroides mutant R26 to chromate stress under photosynthetic conditions is investigated by biochemical and spectroscopic measurements, proteomic analysis and cell imaging. Cell cultures were found able to reduce chromate within 3-4 days. Chromate induces marked changes in the cellular dimension and morphology, as revealed by atomic force microscopy, along with compositional changes in the cell wall revealed by infrared spectroscopy. These effects are accompanied by significant changes in the level of several proteins: 15 proteins were found up-regulated and 15 down-regulated. The protein content found in chromate exposed cells is in good agreement with the biochemical, spectroscopic and microscopic results. Moreover at the present stage no specific chromate-reductase could be found in the soluble proteome, indicating that detoxification of the pollutant proceeds via aspecific reductants."
1445637,Ku et al. 2012,Photocatalytic reduction of Cr(VI) in aqueous solution using TiO? nanoparticles prepared with various alcohols as solvent,"TiO? nanoparticles were prepared with various linear alkyl chains of alcohols under a sol-gel process. The structure characterization and the photocatalytic reduction of hexavalent chromium of the TiO? nanoparticles were investigated. The phase transformation temperature, crystal aggregation and surface area of prepared TiO? samples were found to be strongly influenced by alcohol used. The phase transformation from anatase to rutile was retarded and the surface area was reduced for TiO? prepared with alcohols of longer alkyl chain. TiO? nanoparticles prepared with methanol or ethanol exhibited higher photocatalytic reduction activity of hexavalent chromium possibly due to greater and more positively charged surface area.","Photocatalytic reduction of Cr(VI) in aqueous solution using TiO? nanoparticles prepared with various alcohols as solvent Abs: TiO? nanoparticles were prepared with various linear alkyl chains of alcohols under a sol-gel process. The structure characterization and the photocatalytic reduction of hexavalent chromium of the TiO? nanoparticles were investigated. The phase transformation temperature, crystal aggregation and surface area of prepared TiO? samples were found to be strongly influenced by alcohol used. The phase transformation from anatase to rutile was retarded and the surface area was reduced for TiO? prepared with alcohols of longer alkyl chain. TiO? nanoparticles prepared with methanol or ethanol exhibited higher photocatalytic reduction activity of hexavalent chromium possibly due to greater and more positively charged surface area."
1444932,Rajeh et al. 2012,"Acute toxicity impacts of Euphorbia hirta L extract on behavior, organs body weight index and histopathology of organs of the mice and Artemia salina","<strong>BACKGROUND: </strong>The methanol extract of Euphorbia hirta L (Euphorbiaceae), which is used in traditional medicines, was tested for in vivo toxicity.<br /><br /><strong>MATERIALS AND METHODS: </strong>In vivo brine shrimp lethality assay and oral acute toxicity study at single high dose of 5000 mg/kg and observation for 14 days in mice were used to study the toxic effect of E. hirta.<br /><br /><strong>RESULTS: </strong>Brine shrimp lethality assay was used to calculate the median lethal concentration (LC(50)) of E. hirta (for leaves, stems, flowers and roots) methanolic extracts at concentrations from 100 to 0.07 mg/ml. The LC(50) values of 1.589, 1.420, 0.206 and 0.0827 mg/ml were obtained for stems, leaves, flowers and roots, respectively. Potassium dichromate (the positive control) had LC(50) value of 0.00758 mg/ml. The acute oral toxicity study of the leaf extract resulted in one third mortality and mild behavioral changes among the treated mice. No significant statistical differences found between body weight, relative (%) and absolute (g) organ weights of treated and untreated groups (P&gt; 0.05). Gross and microscopic examination of the vital organ tissues revealed no differences between control and treated mice. All the tissues appeared normal.<br /><br /><strong>CONCLUSIONS: </strong>E. hirta leaves methanol extract has exhibited mild toxic effects in mice.","Acute toxicity impacts of Euphorbia hirta L extract on behavior, organs body weight index and histopathology of organs of the mice and Artemia salina Abs: <strong>BACKGROUND: </strong>The methanol extract of Euphorbia hirta L (Euphorbiaceae), which is used in traditional medicines, was tested for in vivo toxicity.<br /><br /><strong>MATERIALS AND METHODS: </strong>In vivo brine shrimp lethality assay and oral acute toxicity study at single high dose of 5000 mg/kg and observation for 14 days in mice were used to study the toxic effect of E. hirta.<br /><br /><strong>RESULTS: </strong>Brine shrimp lethality assay was used to calculate the median lethal concentration (LC(50)) of E. hirta (for leaves, stems, flowers and roots) methanolic extracts at concentrations from 100 to 0.07 mg/ml. The LC(50) values of 1.589, 1.420, 0.206 and 0.0827 mg/ml were obtained for stems, leaves, flowers and roots, respectively. Potassium dichromate (the positive control) had LC(50) value of 0.00758 mg/ml. The acute oral toxicity study of the leaf extract resulted in one third mortality and mild behavioral changes among the treated mice. No significant statistical differences found between body weight, relative (%) and absolute (g) organ weights of treated and untreated groups (P&gt; 0.05). Gross and microscopic examination of the vital organ tissues revealed no differences between control and treated mice. All the tissues appeared normal.<br /><br /><strong>CONCLUSIONS: </strong>E. hirta leaves methanol extract has exhibited mild toxic effects in mice."
1444430,Weeks et al. 2004,"Synthesis and characterization of a chromium(V) cis-dioxo bis(1,10-phenanthroline) complex and crystal and molecular structures of its chromium(III) precursor","The first structurally characterized Cr(V) dioxo complex, cis-[CrV(O)2(phen)2](BF4) (2, phen=1,10-phenanthroline) has been synthesized by the oxidation of a related Cr(III) complex, cis-[Cr(III)(phen)2(OH2)2](NO3)3.2.5H2O (1, characterized by X-ray crystallography), with NaOCl in aqueous solutions in the presence of excess NaBF4, and its purity has been confirmed by electrospray mass spectrometry (ESMS), EPR spectroscopy, and analytical techniques. Previously reported methods for the generation of Cr(V)-phen complexes, such as the oxidation of 1 with PbO2 or PhIO, have been shown by ESMS to lead to mixtures of Cr(III), Cr(V), Cr(VI), and in some cases Cr(IV) species, 3. Species 3 was assigned as [CrIV(O)(OH)(phen)2]+, based on ESMS and X-ray absorption spectroscopy measurements. A distorted octahedral structure for 2 (CrO, 1.63 A; Cr-N, 2.04 and 2.16 A) was established by multiple-scattering (MS) modeling of XAFS spectra (solid, 10 K). The validity of the model was verified by a good agreement between the results of MS XAFS fitting and X-ray crystallography for 1 (distorted octahedron; Cr-O, 1.95 A; Cr-N, 2.06 A). Unlike for the well-studied Cr(V) 2-hydroxycarboxylato complexes, 2 was equally or more stable in aqueous media (hours at pH=1-13 and 25 degrees C) compared with polar aprotic solvents. A stable Cr(III)-Cr(VI) dimer, [Cr(III)(Cr(VI)O4)(phen)2]+ (detected by ESMS), is formed during the decomposition of 2 in nonaqueous media. Comparative studies of the oxidation of 1 by NaOCl or PbO2 have shown that [Cr(V)(O)2(phen)2]+ was the active species responsible for the previously reported oxidative DNA damage, bacterial mutagenicity, and increased incidence of micronuclei in mammalian cells, caused by the oxidation products of 1 with PbO2. Efficient oxidation of 1 to a genotoxic species, [Cr(V)(O)2(phen)2]+, in neutral aqueous media by a biological oxidant, hypochlorite, supports the hypothesis on a significant role of reoxidation of Cr(III) complexes, formed during the intracellular reduction of Cr(VI), in Cr(VI)-induced carcinogenicity. Similar oxidation reactions may contribute to the reported adverse effects of a popular nutritional supplement, Cr(III) picolinate.","Synthesis and characterization of a chromium(V) cis-dioxo bis(1,10-phenanthroline) complex and crystal and molecular structures of its chromium(III) precursor Abs: The first structurally characterized Cr(V) dioxo complex, cis-[CrV(O)2(phen)2](BF4) (2, phen=1,10-phenanthroline) has been synthesized by the oxidation of a related Cr(III) complex, cis-[Cr(III)(phen)2(OH2)2](NO3)3.2.5H2O (1, characterized by X-ray crystallography), with NaOCl in aqueous solutions in the presence of excess NaBF4, and its purity has been confirmed by electrospray mass spectrometry (ESMS), EPR spectroscopy, and analytical techniques. Previously reported methods for the generation of Cr(V)-phen complexes, such as the oxidation of 1 with PbO2 or PhIO, have been shown by ESMS to lead to mixtures of Cr(III), Cr(V), Cr(VI), and in some cases Cr(IV) species, 3. Species 3 was assigned as [CrIV(O)(OH)(phen)2]+, based on ESMS and X-ray absorption spectroscopy measurements. A distorted octahedral structure for 2 (CrO, 1.63 A; Cr-N, 2.04 and 2.16 A) was established by multiple-scattering (MS) modeling of XAFS spectra (solid, 10 K). The validity of the model was verified by a good agreement between the results of MS XAFS fitting and X-ray crystallography for 1 (distorted octahedron; Cr-O, 1.95 A; Cr-N, 2.06 A). Unlike for the well-studied Cr(V) 2-hydroxycarboxylato complexes, 2 was equally or more stable in aqueous media (hours at pH=1-13 and 25 degrees C) compared with polar aprotic solvents. A stable Cr(III)-Cr(VI) dimer, [Cr(III)(Cr(VI)O4)(phen)2]+ (detected by ESMS), is formed during the decomposition of 2 in nonaqueous media. Comparative studies of the oxidation of 1 by NaOCl or PbO2 have shown that [Cr(V)(O)2(phen)2]+ was the active species responsible for the previously reported oxidative DNA damage, bacterial mutagenicity, and increased incidence of micronuclei in mammalian cells, caused by the oxidation products of 1 with PbO2. Efficient oxidation of 1 to a genotoxic species, [Cr(V)(O)2(phen)2]+, in neutral aqueous media by a biological oxidant, hypochlorite, supports the hypothesis on a significant role of reoxidation of Cr(III) complexes, formed during the intracellular reduction of Cr(VI), in Cr(VI)-induced carcinogenicity. Similar oxidation reactions may contribute to the reported adverse effects of a popular nutritional supplement, Cr(III) picolinate."
1444429,Gez et al. 2005,"Chromium(V) complexes of hydroxamic acids: formation, structures, and reactivities","A new family of relatively stable Cr(V) complexes, [Cr(V)O(L)(2)](-) (LH(2) = RC(O)NHOH, R = Me, Ph, 2-HO-Ph, or HONHC(O)(CH(2))(6)), has been obtained by the reactions of hydroxamic acids with Cr(VI) in polar aprotic solvents. Similar reactions in aqueous solutions led to the formation of transient Cr(V) species. All complexes have been characterized by electron paramagnetic resonance spectroscopy and electrospray mass spectrometry. A Cr(V) complex of benzohydroxamic acid (1, R = Ph) was isolated in a pure form (as a K(+) salt) and was characterized by X-ray absorption spectroscopy and analytical techniques. Multiple-scattering analysis of X-ray absorption fine structure spectroscopic data for 1 (solid, 10 K) point to a distorted trigonal-bipyramidal structure with trans-oriented Ph groups and Cr-ligand bond lengths of 1.58 A (Cr-O), 1.88 A (Cr-O(C)), and 1.98 A (Cr-O(N)). Under ambient conditions, 1 is stable for days in aprotic solvents but decomposes within minutes in aqueous solutions (maximal stability at pH approximately 7), which leads predominantly to the formation of Cr(III) complexes. Complex 1 readily undergoes ligand-exchange reactions with biological 1,2-diols, including D-glucose and mucin, in neutral aqueous solutions. It differs from most other types of Cr(V) complexes in its biological activity, since no oxidative cleavage of plasmid DNA in vitro and no significant bacterial mutagenicity (in the TA 102 strain of Salmonella typhimurium) was observed for 1. In natural systems, stabilization of Cr(V) by hydroxamato ligands from bacterial-derived siderophores (followed by ligand-exchange reactions with more abundant carbohydrate ligands) may occur during the biological reduction of Cr(VI) in contaminated soils.","Chromium(V) complexes of hydroxamic acids: formation, structures, and reactivities Abs: A new family of relatively stable Cr(V) complexes, [Cr(V)O(L)(2)](-) (LH(2) = RC(O)NHOH, R = Me, Ph, 2-HO-Ph, or HONHC(O)(CH(2))(6)), has been obtained by the reactions of hydroxamic acids with Cr(VI) in polar aprotic solvents. Similar reactions in aqueous solutions led to the formation of transient Cr(V) species. All complexes have been characterized by electron paramagnetic resonance spectroscopy and electrospray mass spectrometry. A Cr(V) complex of benzohydroxamic acid (1, R = Ph) was isolated in a pure form (as a K(+) salt) and was characterized by X-ray absorption spectroscopy and analytical techniques. Multiple-scattering analysis of X-ray absorption fine structure spectroscopic data for 1 (solid, 10 K) point to a distorted trigonal-bipyramidal structure with trans-oriented Ph groups and Cr-ligand bond lengths of 1.58 A (Cr-O), 1.88 A (Cr-O(C)), and 1.98 A (Cr-O(N)). Under ambient conditions, 1 is stable for days in aprotic solvents but decomposes within minutes in aqueous solutions (maximal stability at pH approximately 7), which leads predominantly to the formation of Cr(III) complexes. Complex 1 readily undergoes ligand-exchange reactions with biological 1,2-diols, including D-glucose and mucin, in neutral aqueous solutions. It differs from most other types of Cr(V) complexes in its biological activity, since no oxidative cleavage of plasmid DNA in vitro and no significant bacterial mutagenicity (in the TA 102 strain of Salmonella typhimurium) was observed for 1. In natural systems, stabilization of Cr(V) by hydroxamato ligands from bacterial-derived siderophores (followed by ligand-exchange reactions with more abundant carbohydrate ligands) may occur during the biological reduction of Cr(VI) in contaminated soils."
1444426,Nguyen et al. 2008,Reactivity of chromium(III) nutritional supplements in biological media: an X-ray absorption spectroscopic study,"Chromium(III) nutritional supplements are widely used due to their purported ability to enhance glucose metabolism, despite growing evidence on low activity and the potential genotoxicity of these compounds. Reactivities of Cr(III) complexes used in nutritional formulations, including [Cr3O(OCOEt)6(OH2)3](+) (A), [Cr(pic)3] (pic=2-pyridinecarboxylato(-) (B), and trans-[CrCl2(OH2)4](+) (CrCl3.6H2O; C), in a range of natural and simulated biological media (artificial digestion systems, blood and its components, cell culture media, and intact L6 rat skeletal muscle cells) were studied by X-ray absorption near-edge structure (XANES) spectroscopy. The XANES spectroscopic data were processed by multiple linear-regression analyses with the use of a library of model Cr(III) compounds, and the results were corroborated by the results of X-ray absorption fine structure spectroscopy and electrospray mass spectrometry. Complexes A and B underwent extensive ligand-exchange reactions under conditions of combined gastric and intestinal digestion (in the presence of a semisynthetic meal, 3 h at 310 K), as well as in blood serum and in a cell culture medium (1-24 h at 310 K), with the formation of Cr(III) complexes with hydroxo and amino acid/protein ligands. Reactions of compounds A-C with cultured muscle cells led to similar ligand-exchange products, with at least part of Cr(III) bound to the surface of the cells. The reactions of B with serum greatly enhanced its propensity to be converted to Cr(VI) by biological oxidants (H2O2 or glucose oxidase system), which is proposed to be a major cause of both the insulin-enhancing activity and toxicity of Cr(III) compounds (Mulyani, I.; Levina, A.; Lay, P. A. Angew. Chem. Int. Ed. 2004, 43, 4504-4507). This finding enhances the current concern over the safety of consumption of large doses of Cr(III) supplements, particularly [Cr(pic)3].","Reactivity of chromium(III) nutritional supplements in biological media: an X-ray absorption spectroscopic study Abs: Chromium(III) nutritional supplements are widely used due to their purported ability to enhance glucose metabolism, despite growing evidence on low activity and the potential genotoxicity of these compounds. Reactivities of Cr(III) complexes used in nutritional formulations, including [Cr3O(OCOEt)6(OH2)3](+) (A), [Cr(pic)3] (pic=2-pyridinecarboxylato(-) (B), and trans-[CrCl2(OH2)4](+) (CrCl3.6H2O; C), in a range of natural and simulated biological media (artificial digestion systems, blood and its components, cell culture media, and intact L6 rat skeletal muscle cells) were studied by X-ray absorption near-edge structure (XANES) spectroscopy. The XANES spectroscopic data were processed by multiple linear-regression analyses with the use of a library of model Cr(III) compounds, and the results were corroborated by the results of X-ray absorption fine structure spectroscopy and electrospray mass spectrometry. Complexes A and B underwent extensive ligand-exchange reactions under conditions of combined gastric and intestinal digestion (in the presence of a semisynthetic meal, 3 h at 310 K), as well as in blood serum and in a cell culture medium (1-24 h at 310 K), with the formation of Cr(III) complexes with hydroxo and amino acid/protein ligands. Reactions of compounds A-C with cultured muscle cells led to similar ligand-exchange products, with at least part of Cr(III) bound to the surface of the cells. The reactions of B with serum greatly enhanced its propensity to be converted to Cr(VI) by biological oxidants (H2O2 or glucose oxidase system), which is proposed to be a major cause of both the insulin-enhancing activity and toxicity of Cr(III) compounds (Mulyani, I.; Levina, A.; Lay, P. A. Angew. Chem. Int. Ed. 2004, 43, 4504-4507). This finding enhances the current concern over the safety of consumption of large doses of Cr(III) supplements, particularly [Cr(pic)3]."
1444425,Bartholomäus et al. 2012,"Synthesis and characterization of a chromium(V) cis-1,2-cyclohexanediolato complex: a model of reactive intermediates in chromium-induced cancers","Stabilization of chromium(V) by biological 1,2-diolato ligands, e.g., carbohydrates and glycoproteins, is postulated to be crucial for both the chromium(VI)-induced carcinogenicity and chromium(III) antidiabetic activities. Close structural mimics of biologically relevant chromium(V) 1,2-diolato complexes, M[Cr(V)O(chd)(2)] [chd = cis-1,2-cyclohexanediolato(2-)], were synthesized and characterized by X-ray crystallography (M = Na) or by spectroscopic techniques, including X-ray absorption spectroscopy (M = K). This is the first structurally characterized chromium(V) complex with a cyclic diolato ligand.","Synthesis and characterization of a chromium(V) cis-1,2-cyclohexanediolato complex: a model of reactive intermediates in chromium-induced cancers Abs: Stabilization of chromium(V) by biological 1,2-diolato ligands, e.g., carbohydrates and glycoproteins, is postulated to be crucial for both the chromium(VI)-induced carcinogenicity and chromium(III) antidiabetic activities. Close structural mimics of biologically relevant chromium(V) 1,2-diolato complexes, M[Cr(V)O(chd)(2)] [chd = cis-1,2-cyclohexanediolato(2-)], were synthesized and characterized by X-ray crystallography (M = Na) or by spectroscopic techniques, including X-ray absorption spectroscopy (M = K). This is the first structurally characterized chromium(V) complex with a cyclic diolato ligand."
1444364,Schnackenberg et al. 2007,Evaluation of NMR spectral data of urine in conjunction with measured clinical chemistry and histopathology parameters to assess the effects of liver and kidney toxicants,,Evaluation of NMR spectral data of urine in conjunction with measured clinical chemistry and histopathology parameters to assess the effects of liver and kidney toxicants Abs: 
1443719,Franco 2009,The measurement and importance of red cell survival,"The measurement of red blood cell survival in the circulation has progressed from the original differential agglutination technique of Ashby to current isotopic and flow cytometric methods. While occasionally useful in the clinic, these methods find widespread use in a number of important research areas, including the evaluation of new red cell storage media in transfusion medicine and studies of the pathophysiology of sickle cell disease and diabetes. In this review, measurement techniques are placed in historical perspective and examined for relative merits and suitable application.","The measurement and importance of red cell survival Abs: The measurement of red blood cell survival in the circulation has progressed from the original differential agglutination technique of Ashby to current isotopic and flow cytometric methods. While occasionally useful in the clinic, these methods find widespread use in a number of important research areas, including the evaluation of new red cell storage media in transfusion medicine and studies of the pathophysiology of sickle cell disease and diabetes. In this review, measurement techniques are placed in historical perspective and examined for relative merits and suitable application."
1441555,Bach and  Et 1989,INTERNATIONAL MEETING ON THE HEALTH SIGNIFICANCE AND EARLY DETECTION OF NEPHROTOXICITY HELD AT THE JOINT COMMISSION OF THE EUROPEAN COMMUNITIES-INTERNATIONAL PROGRAM ON CHEMICAL SAFETY WORKSHOP LUXEMBOURG APRIL 26-29 1988,BIOSIS COPYRIGHT: BIOL ABS. RRM HUMAN MAMMAL,INTERNATIONAL MEETING ON THE HEALTH SIGNIFICANCE AND EARLY DETECTION OF NEPHROTOXICITY HELD AT THE JOINT COMMISSION OF THE EUROPEAN COMMUNITIES-INTERNATIONAL PROGRAM ON CHEMICAL SAFETY WORKSHOP LUXEMBOURG APRIL 26-29 1988 Abs: BIOSIS COPYRIGHT: BIOL ABS. RRM HUMAN MAMMAL
1438632,Kourtev et al. 2006,Responses of the anaerobic bacterial community to addition of organic C in chromium(VI)- and iron(III)-amended microcosms,"Chromium (VI) is toxic to microorganisms and can inhibit the biodegradation of organic pollutants in contaminated soils. We used microcosms amended with either glucose or protein (to drive bacterial community change) and Fe(III) (to stimulate iron-reducing bacteria) to study the effect of various concentrations of Cr(VI) on anaerobic bacterial communities. Microcosms were destructively sampled based on microbial activity (measured as evolution of CO2) and analyzed for the following: (i) dominant bacterial community by PCR-denaturing gradient gel electrophoresis (DGGE) of the 16S rRNA gene; (ii) culturable Cr-resistant bacteria; and (iii) enrichment of iron-reducing bacteria of the Geobacteraceae family by real-time PCR. The addition of organic C stimulated the activities of anaerobic communities. Cr(VI) amendment resulted in lower rates of CO2 production in glucose microcosms and a slow mineralization phase in protein-amended microcosms. Glucose and protein amendments selected for different bacterial communities. This selection was modified by the addition of Cr(VI), since some DGGE bands were intensified and new bands appeared in Cr(VI)-amended microcosms. A second dose of Cr(VI), added after the onset of activity, had a strong inhibitory effect when higher levels of Cr were added, indicating that the developing Cr-resistant communities had a relatively low tolerance threshold. Most of the isolated Cr-resistant bacteria were closely related to previously studied Cr-resistant anaerobes, such as Pantoea, Pseudomonas, and Enterobacter species. Geobacteraceae were not enriched during the incubation. The studied Cr(VI)-contaminated soil contained a viable anaerobic bacterial community; however, Cr(VI) altered its composition, which could affect the soil biodegradation potential.","Responses of the anaerobic bacterial community to addition of organic C in chromium(VI)- and iron(III)-amended microcosms Abs: Chromium (VI) is toxic to microorganisms and can inhibit the biodegradation of organic pollutants in contaminated soils. We used microcosms amended with either glucose or protein (to drive bacterial community change) and Fe(III) (to stimulate iron-reducing bacteria) to study the effect of various concentrations of Cr(VI) on anaerobic bacterial communities. Microcosms were destructively sampled based on microbial activity (measured as evolution of CO2) and analyzed for the following: (i) dominant bacterial community by PCR-denaturing gradient gel electrophoresis (DGGE) of the 16S rRNA gene; (ii) culturable Cr-resistant bacteria; and (iii) enrichment of iron-reducing bacteria of the Geobacteraceae family by real-time PCR. The addition of organic C stimulated the activities of anaerobic communities. Cr(VI) amendment resulted in lower rates of CO2 production in glucose microcosms and a slow mineralization phase in protein-amended microcosms. Glucose and protein amendments selected for different bacterial communities. This selection was modified by the addition of Cr(VI), since some DGGE bands were intensified and new bands appeared in Cr(VI)-amended microcosms. A second dose of Cr(VI), added after the onset of activity, had a strong inhibitory effect when higher levels of Cr were added, indicating that the developing Cr-resistant communities had a relatively low tolerance threshold. Most of the isolated Cr-resistant bacteria were closely related to previously studied Cr-resistant anaerobes, such as Pantoea, Pseudomonas, and Enterobacter species. Geobacteraceae were not enriched during the incubation. The studied Cr(VI)-contaminated soil contained a viable anaerobic bacterial community; however, Cr(VI) altered its composition, which could affect the soil biodegradation potential."
1432836,CORP 1973,"Environmental levels of radioactivity at Atomic Energy Commission installations: Paducah Plant, January-December 1971","HEEP COPYRIGHT: BIOL ABS. Air, water, soil, and grass in the vicinity of the Paducah Gaseous Diffusion Plant (PGDP), USA, were continuously or periodically sampled during 1971. Analyses for materials known to be in plant effluents were made to provide effluent control information and to determine compliance with applicable air and water quality standards. The air analyses for radioactivity indicate concentrations at all offsite sampling stations averaged less than 1% of the applicable AEC standards. Air and grass offsite analyses for F-- met the Kentucky air quality requirements. A set of soil samples collected to provide historical background data was analyzed for U. There was no detectable change in chemical, and physical, or radioactive characteristics of either the Ohio River or ground water attributable to PGPP operations. The results of water sample analyses of the Ohio River show the Cr and F concentrations were in compliance with the requirements of the applicable Kentucky regulations. The concentration of hexavalent chromium at the mouth of the combined Big and Little Bayous is slightly in excess of the sanitation commission discharge standard of 0.05 ppm.","Environmental levels of radioactivity at Atomic Energy Commission installations: Paducah Plant, January-December 1971 Abs: HEEP COPYRIGHT: BIOL ABS. Air, water, soil, and grass in the vicinity of the Paducah Gaseous Diffusion Plant (PGDP), USA, were continuously or periodically sampled during 1971. Analyses for materials known to be in plant effluents were made to provide effluent control information and to determine compliance with applicable air and water quality standards. The air analyses for radioactivity indicate concentrations at all offsite sampling stations averaged less than 1% of the applicable AEC standards. Air and grass offsite analyses for F-- met the Kentucky air quality requirements. A set of soil samples collected to provide historical background data was analyzed for U. There was no detectable change in chemical, and physical, or radioactive characteristics of either the Ohio River or ground water attributable to PGPP operations. The results of water sample analyses of the Ohio River show the Cr and F concentrations were in compliance with the requirements of the applicable Kentucky regulations. The concentration of hexavalent chromium at the mouth of the combined Big and Little Bayous is slightly in excess of the sanitation commission discharge standard of 0.05 ppm."
1431010,Mayer et al. 1995,GROUNDWATER QUALITY,BIOSIS COPYRIGHT: BIOL ABS. RRM LITERATURE REVIEW GROUNDWATER ENVIRONMENTAL QUALITY NONAQUEOUS PHASE LIQUIDS VADOSE ZONE SYSTEMS POLLUTANT FATE POLLUTANT TRANSPORT POLLUTION WATER CONTAMINATION,GROUNDWATER QUALITY Abs: BIOSIS COPYRIGHT: BIOL ABS. RRM LITERATURE REVIEW GROUNDWATER ENVIRONMENTAL QUALITY NONAQUEOUS PHASE LIQUIDS VADOSE ZONE SYSTEMS POLLUTANT FATE POLLUTANT TRANSPORT POLLUTION WATER CONTAMINATION
1431008,Cowan et al. 1995,ACTIVATED SLUDGE AND OTHER AEROBIC SUSPENDED CULTURE PROCESSES,BIOSIS COPYRIGHT: BIOL ABS. RRM LITERATURE REVIEW ACTIVATED SLUDGE PROCESS MODELING AEROBIC SUSPENDED CULTURES BIOPROCESS ENGINEERING BIOREMEDIATION WASTEWATER TREATMENT NITROGEN CONTROL PHOSPHORUS CONTROL XENOBIOTICS INDUSTRIAL WASTE PROCESS DESIGN SOLIDS SEPARATION OXYGEN TRANSFER WASTE MANAGEMENT BIOREMEDIATION METHOD,ACTIVATED SLUDGE AND OTHER AEROBIC SUSPENDED CULTURE PROCESSES Abs: BIOSIS COPYRIGHT: BIOL ABS. RRM LITERATURE REVIEW ACTIVATED SLUDGE PROCESS MODELING AEROBIC SUSPENDED CULTURES BIOPROCESS ENGINEERING BIOREMEDIATION WASTEWATER TREATMENT NITROGEN CONTROL PHOSPHORUS CONTROL XENOBIOTICS INDUSTRIAL WASTE PROCESS DESIGN SOLIDS SEPARATION OXYGEN TRANSFER WASTE MANAGEMENT BIOREMEDIATION METHOD
1430864,Cowan et al. 1997,ACTIVATED SLUDGE AND OTHER AEROBIC SUSPENDED CULTURE PROCESSES,BIOSIS COPYRIGHT: BIOL ABS. RRM LITERATURE REVIEW ACTIVATED SLUDGE AEROBIC SUSPENDED CULTURE WATER QUALITY WASTEWATER TREATMENT PROCESS MICROBIOLOGY NITROGEN PHOSPHORUS XENOBIOTICS INDUSTRIAL WASTE OXYGEN TRANSFER SOLIDS SEPARATION WASTE MANAGEMENT BIOPROCESS ENGINEERING,ACTIVATED SLUDGE AND OTHER AEROBIC SUSPENDED CULTURE PROCESSES Abs: BIOSIS COPYRIGHT: BIOL ABS. RRM LITERATURE REVIEW ACTIVATED SLUDGE AEROBIC SUSPENDED CULTURE WATER QUALITY WASTEWATER TREATMENT PROCESS MICROBIOLOGY NITROGEN PHOSPHORUS XENOBIOTICS INDUSTRIAL WASTE OXYGEN TRANSFER SOLIDS SEPARATION WASTE MANAGEMENT BIOPROCESS ENGINEERING
1430799,Lovley and  Coates 1997,BIOREMEDIATION OF METAL CONTAMINATION,BIOSIS COPYRIGHT: BIOL ABS. RRM LITERATURE REVIEW BACTERIA FUNGI BIOPROCESS ENGINEERING BIOREMEDIATION METAL CONTAMINATION POLLUTION BIOSORPTION,BIOREMEDIATION OF METAL CONTAMINATION Abs: BIOSIS COPYRIGHT: BIOL ABS. RRM LITERATURE REVIEW BACTERIA FUNGI BIOPROCESS ENGINEERING BIOREMEDIATION METAL CONTAMINATION POLLUTION BIOSORPTION
1420922,Volesky 1994,Advances in biosorption of metals: selection of biomass types,"Within the past decade, the potential of metal biosorption has been well established. For economic reasons, of particular interest are abundant biomass types either generated as a waste by-product of large-scale industrial fermentations or certain metal-binding algae found in large quantities in the sea. Some of these high metal-sorbing biomass types serve as a basis for newly developed metal biosorption processes foreseen particularly as a very competitive means for detoxification of metal-bearing industrial effluents. Ions of lead and cadmium, for instance, have been found to be bound very efficiently from very dilute solutions by the dried biomass of some ubiquitous brown marine algae such as Ascophyllum and Sargassum which accumulate more than 30% of biomass dry weight in the metal. Mycelia of industrially steroid-transforming fungi Rhizopus and Absidia are excellent biosorbents for lead, cadmium, copper, zinc, and uranium, binding also other heavy metals up to 25% of the biomass dry weight. The common yeast Saccharomyces cerevisiae is a 'mediocre' metal biosorbent. Construction of biosorption isotherm curves serves as a basic technique assisting in evaluation of the metal uptake by different biosorbents. The methodology is based on batch equilibrium sorption experiments extensively used for screening and quantitative comparison of new biosorbent materials. Experimental methodologies used in the study of biosorption and selected recent research results demonstrate the route to novel biosorbent materials some of which can even be repeatedly regenerated for re-use.","Advances in biosorption of metals: selection of biomass types Abs: Within the past decade, the potential of metal biosorption has been well established. For economic reasons, of particular interest are abundant biomass types either generated as a waste by-product of large-scale industrial fermentations or certain metal-binding algae found in large quantities in the sea. Some of these high metal-sorbing biomass types serve as a basis for newly developed metal biosorption processes foreseen particularly as a very competitive means for detoxification of metal-bearing industrial effluents. Ions of lead and cadmium, for instance, have been found to be bound very efficiently from very dilute solutions by the dried biomass of some ubiquitous brown marine algae such as Ascophyllum and Sargassum which accumulate more than 30% of biomass dry weight in the metal. Mycelia of industrially steroid-transforming fungi Rhizopus and Absidia are excellent biosorbents for lead, cadmium, copper, zinc, and uranium, binding also other heavy metals up to 25% of the biomass dry weight. The common yeast Saccharomyces cerevisiae is a 'mediocre' metal biosorbent. Construction of biosorption isotherm curves serves as a basic technique assisting in evaluation of the metal uptake by different biosorbents. The methodology is based on batch equilibrium sorption experiments extensively used for screening and quantitative comparison of new biosorbent materials. Experimental methodologies used in the study of biosorption and selected recent research results demonstrate the route to novel biosorbent materials some of which can even be repeatedly regenerated for re-use."
1420679,Sánchez et al. 2001,Nephrotoxicity of simultaneous exposure to mercury and uranium in comparison to individual effects of these metals in rats,"Both inorganic mercury and uranium are known nephrotoxicants in mammals. In this study, the renal toxicity of a concurrent exposure to inorganic mercury and uranium was compared with the nephrotoxic effects of the individual metals in a rat model. Eight groups of rats, 10 animals per group, were subcutaneously given a single administration of mercuric chloride (HgCl2, 0.34 mg/kg and 0.68 mg/kg), uranyl acetate dihydrate (UAD, 2.5 mg/kg and 5 mg/kg), or combinations of both compounds at the same doses. A ninth group of rats received sc injections of 0.9% saline and was designated as the control group. Necrosis of proximal tubules, which was observed in all experimental groups, was the most relevant morphologic abnormality. Marked changes, which were remarkably greater than those induced by the individual elements, were noted in some urinary parameters in the groups concurrently exposed to HgCl2 and UAD. It could be an indicator of a synergistic interaction between mercury and uranium. In contrast, compared with the urinary levels found after individual administration of the highest doses of mercury and uranium, significant reductions in the urinary concentrations of these elements were noted following simultaneous exposure to both metals. At these doses, the reduction in the urinary metal excretion was also accompanied by significant decreases in the renal content of mercury and uranium. Whereas the results of some parameters pointed out a possible synergistic interaction between mercury and uranium, other measures hinted that an antagonistic interaction between these elements is also present.","Nephrotoxicity of simultaneous exposure to mercury and uranium in comparison to individual effects of these metals in rats Abs: Both inorganic mercury and uranium are known nephrotoxicants in mammals. In this study, the renal toxicity of a concurrent exposure to inorganic mercury and uranium was compared with the nephrotoxic effects of the individual metals in a rat model. Eight groups of rats, 10 animals per group, were subcutaneously given a single administration of mercuric chloride (HgCl2, 0.34 mg/kg and 0.68 mg/kg), uranyl acetate dihydrate (UAD, 2.5 mg/kg and 5 mg/kg), or combinations of both compounds at the same doses. A ninth group of rats received sc injections of 0.9% saline and was designated as the control group. Necrosis of proximal tubules, which was observed in all experimental groups, was the most relevant morphologic abnormality. Marked changes, which were remarkably greater than those induced by the individual elements, were noted in some urinary parameters in the groups concurrently exposed to HgCl2 and UAD. It could be an indicator of a synergistic interaction between mercury and uranium. In contrast, compared with the urinary levels found after individual administration of the highest doses of mercury and uranium, significant reductions in the urinary concentrations of these elements were noted following simultaneous exposure to both metals. At these doses, the reduction in the urinary metal excretion was also accompanied by significant decreases in the renal content of mercury and uranium. Whereas the results of some parameters pointed out a possible synergistic interaction between mercury and uranium, other measures hinted that an antagonistic interaction between these elements is also present."
1419766,Brown et al. 2012,Draft genome sequences for two metal-reducing Pelosinus fermentans strains isolated from a Cr(VI)-contaminated site and for type strain R7,"Pelosinus fermentans 16S rRNA gene sequences have been reported from diverse geographical sites since the recent isolation of the type strain. We present the genome sequence of the P. fermentans type strain R7 (DSM 17108) and genome sequences for two new strains with different abilities to reduce iron, chromate, and uranium.","Draft genome sequences for two metal-reducing Pelosinus fermentans strains isolated from a Cr(VI)-contaminated site and for type strain R7 Abs: Pelosinus fermentans 16S rRNA gene sequences have been reported from diverse geographical sites since the recent isolation of the type strain. We present the genome sequence of the P. fermentans type strain R7 (DSM 17108) and genome sequences for two new strains with different abilities to reduce iron, chromate, and uranium."
1418134,Teles et al. 2005,Physiological and genetic responses of European eel (Anguilla anguilla L.) to short-term chromium or copper exposure-Influence of preexposure to a PAH-like compound,"Anguilla anguilla L. (European eel) was exposed for 24 h to chromium (Cr-100 microM and 1 mM) or copper (Cu-1 and 2.5 microM), with or without a 24-h preexposure to beta-naphthoflavone (BNF-2.7 microM), a polycyclic aromatic hydrocarbon (PAH)-like compound, simulating sequential exposure to PAHs and heavy metals. Plasma cortisol, thyroid-stimulating hormone (TSH), free triiodothyronine (T3), and free thyroxine (T4) were determined in order to assess the effects on endocrine function. Plasma glucose and lactate also were measured. The frequency of erythrocytic nuclear abnormalities (ENA) was scored as a genotoxicity indicator. Plasma T4 decreased in eels when exposed to Cr only. The interference of BNF preexposure on Cr effects was observed as a significant plasma glucose increase. Single exposures to Cu elevated plasma cortisol and glucose (2.5 microM), as well as plasma lactate (1 microM), whereas a T4 decrease was found for both concentrations. BNF preexposure prevented plasma cortisol and lactate increases; however, a greater T4 decrease was observed in eels exposed to 2.5 microM Cu. Moreover, this pretreatment was crucial for genotoxicity expression because only BNF+2.5 microM Cu-exposed fish exhibited significant ENA induction. In general, plasma T4 was the most affected hormone, as it responded to all Cr and Cu exposure conditions.","Physiological and genetic responses of European eel (Anguilla anguilla L.) to short-term chromium or copper exposure-Influence of preexposure to a PAH-like compound Abs: Anguilla anguilla L. (European eel) was exposed for 24 h to chromium (Cr-100 microM and 1 mM) or copper (Cu-1 and 2.5 microM), with or without a 24-h preexposure to beta-naphthoflavone (BNF-2.7 microM), a polycyclic aromatic hydrocarbon (PAH)-like compound, simulating sequential exposure to PAHs and heavy metals. Plasma cortisol, thyroid-stimulating hormone (TSH), free triiodothyronine (T3), and free thyroxine (T4) were determined in order to assess the effects on endocrine function. Plasma glucose and lactate also were measured. The frequency of erythrocytic nuclear abnormalities (ENA) was scored as a genotoxicity indicator. Plasma T4 decreased in eels when exposed to Cr only. The interference of BNF preexposure on Cr effects was observed as a significant plasma glucose increase. Single exposures to Cu elevated plasma cortisol and glucose (2.5 microM), as well as plasma lactate (1 microM), whereas a T4 decrease was found for both concentrations. BNF preexposure prevented plasma cortisol and lactate increases; however, a greater T4 decrease was observed in eels exposed to 2.5 microM Cu. Moreover, this pretreatment was crucial for genotoxicity expression because only BNF+2.5 microM Cu-exposed fish exhibited significant ENA induction. In general, plasma T4 was the most affected hormone, as it responded to all Cr and Cu exposure conditions."
1417507,Corrêa et al. 2005,"Tissue distribution, subcellular localization and endocrine disruption patterns induced by Cr and Mn in the crab Ucides cordatus","The essential trace elements Cr and Mn are toxic at high concentrations and information about low concentration is insufficient in the literature. In polluted mangroves, the crab Ucides cordatus can represent a useful tool to assess information on the potential impact of trace elements like Cr and Mn on the environment, since this species is comestible and thus, commercially negotiated. Therefore, U. cordatus crabs were exposed in vivo to different concentrations of Cr and Mn solved in seawater and had their tissue distribution and subcellular deposits evaluated. The gill, hepatopancreas and muscle concentrations were determined by atomic absorption spectroscopy and the results showed that Cr and Mn presented the highest values in the gills rather than in the hepatopancreas and muscular tissue. Electron microscopy and analytical X-ray microanalysis revealed Cr precipitates on the gill surface, co-localized with epiphyte bacteria. In addition, since Cr and Mn did not equally accumulate in most of the tissues studied, glycemic rate of animals, which received injections of extracts of eyestalks of the contaminated crabs, were measured in order to evaluate whether the studied concentrations of Cr and Mn could produce any metabolic alteration. The results indicated that extracts of the eyestalks of crabs submitted to Cr and Mn salts and injected into normal crabs markedly influenced crustacean hyperglycemic hormone synthesis and/or release. The results are discussed with respect to sensitivity of the employed methods and the possible significance of the concentrations of Cr and Mn in the organisms.","Tissue distribution, subcellular localization and endocrine disruption patterns induced by Cr and Mn in the crab Ucides cordatus Abs: The essential trace elements Cr and Mn are toxic at high concentrations and information about low concentration is insufficient in the literature. In polluted mangroves, the crab Ucides cordatus can represent a useful tool to assess information on the potential impact of trace elements like Cr and Mn on the environment, since this species is comestible and thus, commercially negotiated. Therefore, U. cordatus crabs were exposed in vivo to different concentrations of Cr and Mn solved in seawater and had their tissue distribution and subcellular deposits evaluated. The gill, hepatopancreas and muscle concentrations were determined by atomic absorption spectroscopy and the results showed that Cr and Mn presented the highest values in the gills rather than in the hepatopancreas and muscular tissue. Electron microscopy and analytical X-ray microanalysis revealed Cr precipitates on the gill surface, co-localized with epiphyte bacteria. In addition, since Cr and Mn did not equally accumulate in most of the tissues studied, glycemic rate of animals, which received injections of extracts of eyestalks of the contaminated crabs, were measured in order to evaluate whether the studied concentrations of Cr and Mn could produce any metabolic alteration. The results indicated that extracts of the eyestalks of crabs submitted to Cr and Mn salts and injected into normal crabs markedly influenced crustacean hyperglycemic hormone synthesis and/or release. The results are discussed with respect to sensitivity of the employed methods and the possible significance of the concentrations of Cr and Mn in the organisms."
1400890,Marouani et al. 2012,Effects of hexavalent chromium on reproductive functions of male adult rats,"Hexavalent chromium is an environmental contaminant which may be associated with reproductive abnormalities in male rats. In the present study, we examined the effect of hexavalent chromium on male reproductive function of rats. Male Wistar rats received a daily intraperitoneal injection of potassium dichromate (1 or 2 mg/kg body weight) for fifteen consecutive days. A decrease in testis weight and an increase in seminal vesicles and prostate weights were demonstrated after chromium treatment. Moreover, a dose-dependent increase in blood and testis chromium levels as well as an increase in FSH and a decrease in LH and testosterone serum levels were detected in treated rats. Histological analysis revealed pronounced morphological alterations with enlarged intracellular spaces, tissue loosening and dramatic loss of gametes in the lumen of the seminiferous tubules of treated rats. In addition, a decreased sperm motility and number of epididymal spermatozoa together with an increased sperm abnormality rate was found in chromium-treated rats in comparison to controls. In rats receiving the higher chromium dose, histological images presented considerably increased areas filled with seminal vesicle and prostate secretions. The mucosal crypts of seminal vesicles and the typical invaginations of prostate were altered. The results suggest that subacute treatment of potassium dichromate promotes reproductive system toxicity and affects testicular function of adult male rats.","Effects of hexavalent chromium on reproductive functions of male adult rats Abs: Hexavalent chromium is an environmental contaminant which may be associated with reproductive abnormalities in male rats. In the present study, we examined the effect of hexavalent chromium on male reproductive function of rats. Male Wistar rats received a daily intraperitoneal injection of potassium dichromate (1 or 2 mg/kg body weight) for fifteen consecutive days. A decrease in testis weight and an increase in seminal vesicles and prostate weights were demonstrated after chromium treatment. Moreover, a dose-dependent increase in blood and testis chromium levels as well as an increase in FSH and a decrease in LH and testosterone serum levels were detected in treated rats. Histological analysis revealed pronounced morphological alterations with enlarged intracellular spaces, tissue loosening and dramatic loss of gametes in the lumen of the seminiferous tubules of treated rats. In addition, a decreased sperm motility and number of epididymal spermatozoa together with an increased sperm abnormality rate was found in chromium-treated rats in comparison to controls. In rats receiving the higher chromium dose, histological images presented considerably increased areas filled with seminal vesicle and prostate secretions. The mucosal crypts of seminal vesicles and the typical invaginations of prostate were altered. The results suggest that subacute treatment of potassium dichromate promotes reproductive system toxicity and affects testicular function of adult male rats."
1393477,Chiba 1987,Determination of Tin in Biological Materials by Atomic-Absorption Spectrometry with a Graphite Furnace,"The analysis of tin (7440315) in blood, liver, kidney, and spleen using atomic absorption spectrometry was reported. Four methods were compared: standard addition, low temperature ashing, wet ashing, and direct determination. Rabbits were injected intravenously with 0.5mg/kg and mice were administered intraperitoneally 1mg/kg of stannous-chloride (7772998) (SnCl2). Plasma was removed from blood samples and erythrocytes were washed with 5 percent glucose. Blood was dried and digested in a plasma reactor. The white ash was dissolved in 6 normal hydrochloric-acid (HCl) and extracted with methylisobutylketone (MIBK). Standard addition involved diluting whole blood with an equal volume of 0.5 percent Triton in HCl. A 20 microliter sample was injected into a graphite tube and phosphoric-acid containing 0.6 percent nickel-nitrate and tin standard was added. Wet ashing involved ashing in nitric-acid and perchloric-acid followed by MIBK extraction. The strongest absorption line was 224.6 nanometers (nm) with the strongest emission line at 284.0nm. The detection limit was 0.2 without the expansion mode and 2.0 nanograms/milliliter with the expansion mode. Charring temperatures were maintained in the 500 to 1100 degrees-C range. Optimal atomizing temperature was chosen at 2700 degrees-C. Addition of ascorbic-acid removed ferric ion interference. The direct method for determination of tin produced scattered results and therefore the procedure was not suitable. Hexavalent chromium and molybdenum, pentavalent vanadium, and trivalent and pentavalent arsenic and antimony did not interfere with MIBK extraction. Ascorbic-acid was effective in removing iron interference in liver, kidney, and spleen specimens. Wet ashing and MIBK extraction was found suitable for the determination of tin in mouse blood. The author recommends wet ashing because of time savings and suitability for large samples.","Determination of Tin in Biological Materials by Atomic-Absorption Spectrometry with a Graphite Furnace Abs: The analysis of tin (7440315) in blood, liver, kidney, and spleen using atomic absorption spectrometry was reported. Four methods were compared: standard addition, low temperature ashing, wet ashing, and direct determination. Rabbits were injected intravenously with 0.5mg/kg and mice were administered intraperitoneally 1mg/kg of stannous-chloride (7772998) (SnCl2). Plasma was removed from blood samples and erythrocytes were washed with 5 percent glucose. Blood was dried and digested in a plasma reactor. The white ash was dissolved in 6 normal hydrochloric-acid (HCl) and extracted with methylisobutylketone (MIBK). Standard addition involved diluting whole blood with an equal volume of 0.5 percent Triton in HCl. A 20 microliter sample was injected into a graphite tube and phosphoric-acid containing 0.6 percent nickel-nitrate and tin standard was added. Wet ashing involved ashing in nitric-acid and perchloric-acid followed by MIBK extraction. The strongest absorption line was 224.6 nanometers (nm) with the strongest emission line at 284.0nm. The detection limit was 0.2 without the expansion mode and 2.0 nanograms/milliliter with the expansion mode. Charring temperatures were maintained in the 500 to 1100 degrees-C range. Optimal atomizing temperature was chosen at 2700 degrees-C. Addition of ascorbic-acid removed ferric ion interference. The direct method for determination of tin produced scattered results and therefore the procedure was not suitable. Hexavalent chromium and molybdenum, pentavalent vanadium, and trivalent and pentavalent arsenic and antimony did not interfere with MIBK extraction. Ascorbic-acid was effective in removing iron interference in liver, kidney, and spleen specimens. Wet ashing and MIBK extraction was found suitable for the determination of tin in mouse blood. The author recommends wet ashing because of time savings and suitability for large samples."
1391940,Kuhlman and  Greenfield 1999,Simplified soil washing processes for a variety of soils,"BIOSIS COPYRIGHT: BIOL ABS. A soil washing process is described in which high shear mixing, sprays, hydrosizing, flotation, and screening are integrated to countercurrently clean sand, silt and clay. Chemical techniques are summarized that can be used to remove selected contaminants from the soil and then clean the wash water for reuse. Descriptions of simple and complex processes, and a recent project are used to illustrate the points: (1) Soil washing is not a single process, but a collection of unit operations assembled","Simplified soil washing processes for a variety of soils Abs: BIOSIS COPYRIGHT: BIOL ABS. A soil washing process is described in which high shear mixing, sprays, hydrosizing, flotation, and screening are integrated to countercurrently clean sand, silt and clay. Chemical techniques are summarized that can be used to remove selected contaminants from the soil and then clean the wash water for reuse. Descriptions of simple and complex processes, and a recent project are used to illustrate the points: (1) Soil washing is not a single process, but a collection of unit operations assembled"
1391790,Calhoun et al. 1995,Sulfur polymer cement encapsulation of RCRA toxic metals and metal oxides,"A study was conducted to determine the suitability of Sulfur Polymer Cement (SPC) encapsulation technology for the stabilization of RCRA toxic metal and metal oxide wastes. In a series of bench-scale experiments, the effects of sodium sulfide additions to the waste mixture, residence time, and temperature profile were evaluated. In addition, an effort was made to ascertain the degree to which SPC affords chemical stabilization as opposed to physical encapsulation. Experimental results have demonstrated that at the 25 wt % loading level, SPC can effectively immobilize Cr, Cr2O3, Hg, Pb, and Se to levels below regulatory limits. SPC encapsulation also has been shown to significantly reduce the leachability of other toxic compounds including PbO, PbO2, As2O3, BaO, and CdO. In addition, data has confirmed sulfide conversion of Hg, Pb, PbO, PbO2, and BaO as the product of their reaction with SPC.","Sulfur polymer cement encapsulation of RCRA toxic metals and metal oxides Abs: A study was conducted to determine the suitability of Sulfur Polymer Cement (SPC) encapsulation technology for the stabilization of RCRA toxic metal and metal oxide wastes. In a series of bench-scale experiments, the effects of sodium sulfide additions to the waste mixture, residence time, and temperature profile were evaluated. In addition, an effort was made to ascertain the degree to which SPC affords chemical stabilization as opposed to physical encapsulation. Experimental results have demonstrated that at the 25 wt % loading level, SPC can effectively immobilize Cr, Cr2O3, Hg, Pb, and Se to levels below regulatory limits. SPC encapsulation also has been shown to significantly reduce the leachability of other toxic compounds including PbO, PbO2, As2O3, BaO, and CdO. In addition, data has confirmed sulfide conversion of Hg, Pb, PbO, PbO2, and BaO as the product of their reaction with SPC."
1390979,Office 1978,Water pollution by organophosphorus compounds,"PESTAB. Among the pollutants in water ways of Japan, organophosphorus compounds are rigorously controlled, and it has been established that these compounds must not be detected in the water system. According to the results of water quality examinations on 107 samples from rivers of Fukushima Prefecture, organophosphorus compounds were not detected from April 1976 to March 1977. Other pollutants such as cyanide, alkyl mercury, cadmium, lead, hexavalent chromium, arsenic, total mercury, and PCB, were also determined.","Water pollution by organophosphorus compounds Abs: PESTAB. Among the pollutants in water ways of Japan, organophosphorus compounds are rigorously controlled, and it has been established that these compounds must not be detected in the water system. According to the results of water quality examinations on 107 samples from rivers of Fukushima Prefecture, organophosphorus compounds were not detected from April 1976 to March 1977. Other pollutants such as cyanide, alkyl mercury, cadmium, lead, hexavalent chromium, arsenic, total mercury, and PCB, were also determined."
1388700,Lau 1969,A review of the literature of 1968 on wastewater and water pollution control: Effects on groundwater,"HAPAB The various factors which affect groundwater pollution are reviewed. Pollutants include nitrates, organics, detergents, viruses and bacteria, mineral oil, radionuclides, other toxic materials and possibly pesticides. A case of arsenic pollution of groundwater in Germany which threatened to contaminate the public water wells is reported. The presence of a high concentration of hexavalent chromium and cyanide in groundwater from wells near a small planting plant in Hungary was discovered. The pollution was very marked in wells up to 120 ft away in the direction of the natural goundwater flow. Theoretical, managerial and special control and management studies are also included in the review. MONITORING AND RESIDUES 70/01/00, 11 1969","A review of the literature of 1968 on wastewater and water pollution control: Effects on groundwater Abs: HAPAB The various factors which affect groundwater pollution are reviewed. Pollutants include nitrates, organics, detergents, viruses and bacteria, mineral oil, radionuclides, other toxic materials and possibly pesticides. A case of arsenic pollution of groundwater in Germany which threatened to contaminate the public water wells is reported. The presence of a high concentration of hexavalent chromium and cyanide in groundwater from wells near a small planting plant in Hungary was discovered. The pollution was very marked in wells up to 120 ft away in the direction of the natural goundwater flow. Theoretical, managerial and special control and management studies are also included in the review. MONITORING AND RESIDUES 70/01/00, 11 1969"
1387299,Quevauviller 1998,Requirements for production and use of certified reference materials for speciation analysis: A European Commission Perspective,"BIOSIS COPYRIGHT: BIOL ABS. This paper describes requirements for the preparation of Certified Reference Materials (CRMs) for speciation analysis, arising from experience gained within a series of interlaboratory studies organized by the European Commission. A range of chemical compounds in various environmental matrices were targeted, e.g. organotins in sediment and mussel, methylmercury in fish and sediment, As-species in fish, trimethyllead in artificial rainwater and urban dust, Cr(III) and Cr(VI) in lyophilized solution and welding dust, and Se(IV) and Se(VI) in artificial freshwater.","Requirements for production and use of certified reference materials for speciation analysis: A European Commission Perspective Abs: BIOSIS COPYRIGHT: BIOL ABS. This paper describes requirements for the preparation of Certified Reference Materials (CRMs) for speciation analysis, arising from experience gained within a series of interlaboratory studies organized by the European Commission. A range of chemical compounds in various environmental matrices were targeted, e.g. organotins in sediment and mussel, methylmercury in fish and sediment, As-species in fish, trimethyllead in artificial rainwater and urban dust, Cr(III) and Cr(VI) in lyophilized solution and welding dust, and Se(IV) and Se(VI) in artificial freshwater."
1387272,Hasselriis and  Wood 1998,Evaluation of the potential for health effects due to short-term emissions of metals from incinerators,"BIOSIS COPYRIGHT: BIOL ABS. Half-hour ground level concentrations (GLCs) resulting from worst case emissions of five metals from three types of incinerators were determined assuming that worst case dispersion occurred. For a hazardous waste incinerator (HWI), the metals' GLCs were determined for two situations with extreme assumptions: (1) all of the particulate emissions were composed of a single metal and (2) 5% of the total feed to the incinerator was a single metal. Metal GLCs were also calculated for the HWI, a municipal waste combustor (MWC), and a medical waste incinerator (MWI) under two scenarios: (1) assuming an emergency bypass of the air pollution control equipment (APCE) and (2) using the maximum metals emissions in a comprehensive U.S. database. These GLCs were compared with Immediately Dangerous to Life and Health (IDLH) standards that protect workers from potentially dangerous short-term exposures. The IDLH levels were greater than the maximum one-half hour GLCs by at least a facto","Evaluation of the potential for health effects due to short-term emissions of metals from incinerators Abs: BIOSIS COPYRIGHT: BIOL ABS. Half-hour ground level concentrations (GLCs) resulting from worst case emissions of five metals from three types of incinerators were determined assuming that worst case dispersion occurred. For a hazardous waste incinerator (HWI), the metals' GLCs were determined for two situations with extreme assumptions: (1) all of the particulate emissions were composed of a single metal and (2) 5% of the total feed to the incinerator was a single metal. Metal GLCs were also calculated for the HWI, a municipal waste combustor (MWC), and a medical waste incinerator (MWI) under two scenarios: (1) assuming an emergency bypass of the air pollution control equipment (APCE) and (2) using the maximum metals emissions in a comprehensive U.S. database. These GLCs were compared with Immediately Dangerous to Life and Health (IDLH) standards that protect workers from potentially dangerous short-term exposures. The IDLH levels were greater than the maximum one-half hour GLCs by at least a facto"
1387223,Dietrich and  Jensen 1995,CHEMICAL SPECIES,BIOSIS COPYRIGHT: BIOL ABS. RRM LITERATURE REVIEW CHEMICAL SPECIES SOLID PHASE MICROEXTRACTION SPME METHODOLOGY ENVIRONMENTAL SURVEILLANCE POLLUTION CHEMICAL ANALYSIS METHODS ANALYTICAL METHOD,CHEMICAL SPECIES Abs: BIOSIS COPYRIGHT: BIOL ABS. RRM LITERATURE REVIEW CHEMICAL SPECIES SOLID PHASE MICROEXTRACTION SPME METHODOLOGY ENVIRONMENTAL SURVEILLANCE POLLUTION CHEMICAL ANALYSIS METHODS ANALYTICAL METHOD
1387113,Dabek-Zlotorzynska et al. 1998,Capillary electrophoresis: The state-of-the-art in metal speciation studies,"BIOSIS COPYRIGHT: BIOL ABS. An overview of the state-of-the-art of capillary electrophoresis (CE) for metal speciation analysis is presented. Various CE separation approaches and detection modes applied are discussed. A comprehensive description of reported methods to date in CE speciation studies of individual metals in different oxidation states. metal complexes with inorganic and organic ligands, oxoanions and organometallic compounds is demonstrated. The potential of CE for characterisation of metal interactions with large molecules like humic substances and proteins is also described. Several examples are presented to demonstrate CE's ability to solve real-world speciation problems. Further, the current strengths and limitations of CE with regard to speciation studies are discussed. The performance of CE is also critically evaluated in relationship to conventional chromatographic techniques used in metal speciation determination.","Capillary electrophoresis: The state-of-the-art in metal speciation studies Abs: BIOSIS COPYRIGHT: BIOL ABS. An overview of the state-of-the-art of capillary electrophoresis (CE) for metal speciation analysis is presented. Various CE separation approaches and detection modes applied are discussed. A comprehensive description of reported methods to date in CE speciation studies of individual metals in different oxidation states. metal complexes with inorganic and organic ligands, oxoanions and organometallic compounds is demonstrated. The potential of CE for characterisation of metal interactions with large molecules like humic substances and proteins is also described. Several examples are presented to demonstrate CE's ability to solve real-world speciation problems. Further, the current strengths and limitations of CE with regard to speciation studies are discussed. The performance of CE is also critically evaluated in relationship to conventional chromatographic techniques used in metal speciation determination."
1387082,Ehrlich 1997,Microbes and metals,BIOSIS COPYRIGHT: BIOL ABS. Many base metals and a few precious metals as well as some metalloids can be enzymatically or nonenzymatically concentrated and dispersed by microbes in their environment. Some of these activities are commercially exploited or have a potential for it. This article summarizes these activities and the commercial or potentially commercial use of some of them.,Microbes and metals Abs: BIOSIS COPYRIGHT: BIOL ABS. Many base metals and a few precious metals as well as some metalloids can be enzymatically or nonenzymatically concentrated and dispersed by microbes in their environment. Some of these activities are commercially exploited or have a potential for it. This article summarizes these activities and the commercial or potentially commercial use of some of them.
1386991,Zouboulis and  Matis 1997,REMOVAL OF MEAL IONS FROM DILUTE SOLUTIONS BY SORPTIVE FLOTATION,BIOSIS COPYRIGHT: BIOL ABS. RRM LITERATURE REVIEW INORGANIC SORBENTS MINERAL PARTICLES BIOSORPTION SORPTIVE FLOTATION TOXICOLOGY METAL CATIONS OXYANIONS WASTE MANAGEMENT,REMOVAL OF MEAL IONS FROM DILUTE SOLUTIONS BY SORPTIVE FLOTATION Abs: BIOSIS COPYRIGHT: BIOL ABS. RRM LITERATURE REVIEW INORGANIC SORBENTS MINERAL PARTICLES BIOSORPTION SORPTIVE FLOTATION TOXICOLOGY METAL CATIONS OXYANIONS WASTE MANAGEMENT
1386951,Ellis and  Roberts 1997,Chromatographic and hyphenated methods for elemental speciation analysis in environmental media,"BIOSIS COPYRIGHT: BIOL ABS. This review discusses chromatographic techniques that permit the analysis of speciated metals in the environment using conventional detectors, such as UV, and element-specific detectors, such as flame atomic absorption spectrometry, electrothermal atomic absorption spectrometry and inductively coupled plasma mass spectrometry. The importance of determining precise elemental forms in hazardous waste-contaminated soil, water and biota in terms of toxicity is outlined. Previous reviews on this subject are described and recent research on this subject is discussed. Most of the work cited has been performed in the 1990s and a table summarizing the chromatographic method and the detector system used, including brief comments on the work, is included to enable quick reference.","Chromatographic and hyphenated methods for elemental speciation analysis in environmental media Abs: BIOSIS COPYRIGHT: BIOL ABS. This review discusses chromatographic techniques that permit the analysis of speciated metals in the environment using conventional detectors, such as UV, and element-specific detectors, such as flame atomic absorption spectrometry, electrothermal atomic absorption spectrometry and inductively coupled plasma mass spectrometry. The importance of determining precise elemental forms in hazardous waste-contaminated soil, water and biota in terms of toxicity is outlined. Previous reviews on this subject are described and recent research on this subject is discussed. Most of the work cited has been performed in the 1990s and a table summarizing the chromatographic method and the detector system used, including brief comments on the work, is included to enable quick reference."
1386938,Chaney et al. 1997,PHYTOREMEDIATION OF SOIL METALS,BIOSIS COPYRIGHT: BIOL ABS. RRM LITERATURE REVIEW PLANTS BIOPROCESS ENGINEERING PHYTOREMEDIATION METAL-CONTAMINATED SOILS SELENIUM POLLUTANT MERCURY LEAD CHROMIUM IRON ZINC POLLUTION,PHYTOREMEDIATION OF SOIL METALS Abs: BIOSIS COPYRIGHT: BIOL ABS. RRM LITERATURE REVIEW PLANTS BIOPROCESS ENGINEERING PHYTOREMEDIATION METAL-CONTAMINATED SOILS SELENIUM POLLUTANT MERCURY LEAD CHROMIUM IRON ZINC POLLUTION
1386937,Apostoli 1997,ELEMENT SPECIATION IN BIOLOGICAL MONITORING,BIOSIS COPYRIGHT: BIOL ABS. RRM EDITORIAL HUMAN HUMAN BIOCHEMISTRY AND BIOPHYSICS ELEMENT DETERMINATION ENVIRONMENT BIOLOGICAL SYSTEMS TOXICOLOGY,ELEMENT SPECIATION IN BIOLOGICAL MONITORING Abs: BIOSIS COPYRIGHT: BIOL ABS. RRM EDITORIAL HUMAN HUMAN BIOCHEMISTRY AND BIOPHYSICS ELEMENT DETERMINATION ENVIRONMENT BIOLOGICAL SYSTEMS TOXICOLOGY
1386806,Davies 1997,Deficiencies and toxicities of trace elements and micronutrients in tropical soils: Limitations of knowledge and future research needs,"BIOSIS COPYRIGHT: BIOL ABS. This article reviews present knowledge concerning deficiencies and toxicities of trace elements and micronutrients in tropical soils. The myth that all tropical soils are highly leached and nutrient-poor is challenged. Continuing use of the term ""laterite"" by ecologists and geologists is criticized and adoption of ""plinthite"" is urged. The trace element content of plinthite and its possible influence on micronutrient availability are described. Micronutrient limitations of tropical agriculture are related to soil type and formation, and the special problem of aluminum toxicity in acid soils is discussed in both agricultural and ecological contexts. Studies of micronutrient cycling in tropical forests or savannas are needed to supplement the emerging picture of the complexities of major element cycles in these ecosystems. Interest in gold mining has stimulated studies of the element in tropical soils, and mining of the metal is leading to mercury pollution in Amazonia.","Deficiencies and toxicities of trace elements and micronutrients in tropical soils: Limitations of knowledge and future research needs Abs: BIOSIS COPYRIGHT: BIOL ABS. This article reviews present knowledge concerning deficiencies and toxicities of trace elements and micronutrients in tropical soils. The myth that all tropical soils are highly leached and nutrient-poor is challenged. Continuing use of the term ""laterite"" by ecologists and geologists is criticized and adoption of ""plinthite"" is urged. The trace element content of plinthite and its possible influence on micronutrient availability are described. Micronutrient limitations of tropical agriculture are related to soil type and formation, and the special problem of aluminum toxicity in acid soils is discussed in both agricultural and ecological contexts. Studies of micronutrient cycling in tropical forests or savannas are needed to supplement the emerging picture of the complexities of major element cycles in these ecosystems. Interest in gold mining has stimulated studies of the element in tropical soils, and mining of the metal is leading to mercury pollution in Amazonia."
1386771,Dollerer and  Wilderer 1996,Biological treatment of leachates from hazardous waste landfills using SBBr technology,"BIOSIS COPYRIGHT: BIOL ABS. Bench-scale experiments with two different types of fixed bed reactor have been conducted in order to investigate the potential of SBBr technology (Sequencing Batch Biofilm Reactor) for treatment of leachates from different hazardous waste landfills. Reactor A was equipped with a membrane oxygenation system for bubble free transfer of oxygen into the bulk liquid. In contrast, reactor B was bubble aerated. The process was found to be remarkably stable. An average DOC removal rate of 68% was achieved with a 12-hour cycle. The emission of biodegradable volatile organic substances was observed to be significantly reduced by using bubble free aeration system.","Biological treatment of leachates from hazardous waste landfills using SBBr technology Abs: BIOSIS COPYRIGHT: BIOL ABS. Bench-scale experiments with two different types of fixed bed reactor have been conducted in order to investigate the potential of SBBr technology (Sequencing Batch Biofilm Reactor) for treatment of leachates from different hazardous waste landfills. Reactor A was equipped with a membrane oxygenation system for bubble free transfer of oxygen into the bulk liquid. In contrast, reactor B was bubble aerated. The process was found to be remarkably stable. An average DOC removal rate of 68% was achieved with a 12-hour cycle. The emission of biodegradable volatile organic substances was observed to be significantly reduced by using bubble free aeration system."
1386712,Lange et al. 1996,BIOMONITORING,BIOSIS COPYRIGHT: BIOL ABS. RRM LITERATURE REVIEW HUMAN HEALTH METALS ORGANIC COMPOUNDS ENVIRONMENTAL POLLUTION IMPACTS POLLUTION CONTROL BIOMONITORING PETROLEUM WASTEWATER OUTFALLS AIR POLLUTION ACIDIFICATION FLOW VARIATIONS,BIOMONITORING Abs: BIOSIS COPYRIGHT: BIOL ABS. RRM LITERATURE REVIEW HUMAN HEALTH METALS ORGANIC COMPOUNDS ENVIRONMENTAL POLLUTION IMPACTS POLLUTION CONTROL BIOMONITORING PETROLEUM WASTEWATER OUTFALLS AIR POLLUTION ACIDIFICATION FLOW VARIATIONS
1386658,Mach et al. 1996,Metal speciation: Survey of environmental methods of analysis,"BIOSIS COPYRIGHT: BIOL ABS. As part of a recent task under the EPRI Analytical Methods Qualification Program (RP 1851), TRW has surveyed the methods available for monitoring metal species in typical utility aqueous discharge streams. Methods for determining the individual species of these metals can become important in a regulatory sense as the EPA transitions to assessment of environmental risk based on bioavailability. For example, EPA considers methyl mercury and Cr(VI) much more toxic to the aquatic environment than inorganic mercury or Cr(III). The species of a given element can also differ in their transport and bioaccumulation. Methods for speciation generally include a selective separation step followed by standard metals analysis. Speciation, therefore, is mainly derived from the separation step and not from the method of final quantitation. Examples of separation/analysis include: selective extraction followed by graphite furnace atomic absorption or ICP-MS; separation by GC followed by","Metal speciation: Survey of environmental methods of analysis Abs: BIOSIS COPYRIGHT: BIOL ABS. As part of a recent task under the EPRI Analytical Methods Qualification Program (RP 1851), TRW has surveyed the methods available for monitoring metal species in typical utility aqueous discharge streams. Methods for determining the individual species of these metals can become important in a regulatory sense as the EPA transitions to assessment of environmental risk based on bioavailability. For example, EPA considers methyl mercury and Cr(VI) much more toxic to the aquatic environment than inorganic mercury or Cr(III). The species of a given element can also differ in their transport and bioaccumulation. Methods for speciation generally include a selective separation step followed by standard metals analysis. Speciation, therefore, is mainly derived from the separation step and not from the method of final quantitation. Examples of separation/analysis include: selective extraction followed by graphite furnace atomic absorption or ICP-MS; separation by GC followed by"
1386558,White et al. 1995,The role of microorganisms in biosorption of toxic metals and radionuclides,"BIOSIS COPYRIGHT: BIOL ABS. A multiplicity of physico-chemical and biological mechanisms determine the removal of toxic metals, metalloids and radionuclides from contaminated wastes. Physico-chemical mechanisms of removal, which may be encompassed by the general term ""biosorption"", include adsorption, ion exchange and entrapment which are features of living and dead biomass as well as derived products. In living cells, biosorption can be directly and indirectly influenced by metabolism. Metabolism-dependent mechanisms of metal removal which occur in living microorganisms include metal precipitation as sulphides, complexation by siderophores and other metabolites, sequestration by metal-binding proteins and peptides, transport and intracellular compartmentation. In addition, transformations of metal species can occur resulting in oxidation, reduction or methylation. For metalloids such as selenium, two main transformation mechanisms are the reduction of oxyanions to elemental forms, and methylation","The role of microorganisms in biosorption of toxic metals and radionuclides Abs: BIOSIS COPYRIGHT: BIOL ABS. A multiplicity of physico-chemical and biological mechanisms determine the removal of toxic metals, metalloids and radionuclides from contaminated wastes. Physico-chemical mechanisms of removal, which may be encompassed by the general term ""biosorption"", include adsorption, ion exchange and entrapment which are features of living and dead biomass as well as derived products. In living cells, biosorption can be directly and indirectly influenced by metabolism. Metabolism-dependent mechanisms of metal removal which occur in living microorganisms include metal precipitation as sulphides, complexation by siderophores and other metabolites, sequestration by metal-binding proteins and peptides, transport and intracellular compartmentation. In addition, transformations of metal species can occur resulting in oxidation, reduction or methylation. For metalloids such as selenium, two main transformation mechanisms are the reduction of oxyanions to elemental forms, and methylation"
1386542,Giuliano 1995,GROUND WATER IN THE PO BASIN SOME PROBLEMS RELATING TO ITS USE AND PROTECTION,BIOSIS COPYRIGHT: BIOL ABS. RRM JOURNAL ARTICLE AQUIFER POLLUTION NITRATES HERBICIDES ITALY,GROUND WATER IN THE PO BASIN SOME PROBLEMS RELATING TO ITS USE AND PROTECTION Abs: BIOSIS COPYRIGHT: BIOL ABS. RRM JOURNAL ARTICLE AQUIFER POLLUTION NITRATES HERBICIDES ITALY
1386451,Liu et al. 1995,Environmental Chemical behaviour of Metal Contaminants in Aquatic Environments in China,BIOSIS COPYRIGHT: BIOL ABS. The chemical species of metal contaminants and their transformation in aquatic systems are largely dependent on environmental conditions. This paper reports on some work on metal contamination in a number of rivers in China. Speciation by sequential extraction and some physicochemical processes involving the transformation and transport of metals in the aquatic systems are also reported.,Environmental Chemical behaviour of Metal Contaminants in Aquatic Environments in China Abs: BIOSIS COPYRIGHT: BIOL ABS. The chemical species of metal contaminants and their transformation in aquatic systems are largely dependent on environmental conditions. This paper reports on some work on metal contamination in a number of rivers in China. Speciation by sequential extraction and some physicochemical processes involving the transformation and transport of metals in the aquatic systems are also reported.
1386416,Cruz et al. 1995,Determination of hexavalent chromium in CCA-treated building timbers,"BIOSIS COPYRIGHT: BIOL ABS. Alkaline extraction followed by atomic absorption spectrometry was applied to the speciation and quantification of chromium in CCA-treated building timbers. Total chromium was determined by atomic absorption spectrometry of specimens prepared by acid digestion. The specimens examined were found to contain 0.3-0.4% total chromium, and 100 mg/kg of hexavalent chromium.","Determination of hexavalent chromium in CCA-treated building timbers Abs: BIOSIS COPYRIGHT: BIOL ABS. Alkaline extraction followed by atomic absorption spectrometry was applied to the speciation and quantification of chromium in CCA-treated building timbers. Total chromium was determined by atomic absorption spectrometry of specimens prepared by acid digestion. The specimens examined were found to contain 0.3-0.4% total chromium, and 100 mg/kg of hexavalent chromium."
1386394,Van Loon and  Barefoot 1995,TRENDS AND DEVELOPMENTS,BIOSIS COPYRIGHT: BIOL ABS. RRM BOOK CHAPTER METALS ENVIRONMENTAL POLLUTION SPECIATION ANALYTICAL METHOD,TRENDS AND DEVELOPMENTS Abs: BIOSIS COPYRIGHT: BIOL ABS. RRM BOOK CHAPTER METALS ENVIRONMENTAL POLLUTION SPECIATION ANALYTICAL METHOD
1386358,Nohava et al. 1995,Evaluation of the luminescent bacteria bioassay for the estimation of the toxicological potential of effluent water samples-comparison with data from chemical analysis,"BIOSIS COPYRIGHT: BIOL ABS. Investigations of toxic effects of water samples from industrial plants and landfill effluents on bioluminescent bacteria were carried out. The results of a standardised bioassay (LUMIStox) were compared to chemical analytic data (heavy metal concentrations, COD, and BOD). A reduction of bioluminescent activity was observed in most of the samples. The degree of reduction showed good correlation with the concentrations of anorganic and organic pollutant indicators. The applicability of the luminescent bacteria bioassay for the evaluation of the ecotoxicological potential of these kinds of polluted effluents was demonstrated.","Evaluation of the luminescent bacteria bioassay for the estimation of the toxicological potential of effluent water samples-comparison with data from chemical analysis Abs: BIOSIS COPYRIGHT: BIOL ABS. Investigations of toxic effects of water samples from industrial plants and landfill effluents on bioluminescent bacteria were carried out. The results of a standardised bioassay (LUMIStox) were compared to chemical analytic data (heavy metal concentrations, COD, and BOD). A reduction of bioluminescent activity was observed in most of the samples. The degree of reduction showed good correlation with the concentrations of anorganic and organic pollutant indicators. The applicability of the luminescent bacteria bioassay for the evaluation of the ecotoxicological potential of these kinds of polluted effluents was demonstrated."
1386273,Cambier 1994,CONTAMINATION OF SOILS BY HEAVY METALS AND OTHER TRACE ELEMENTS A CHEMICAL PERSPECTIVE,BIOSIS COPYRIGHT: BIOL ABS. RRM JOURNAL ARTICLE SOIL POLLUTION SOIL QUALITY SOIL CHEMISTRY AGRICULTURE ENVIRONMENT,CONTAMINATION OF SOILS BY HEAVY METALS AND OTHER TRACE ELEMENTS A CHEMICAL PERSPECTIVE Abs: BIOSIS COPYRIGHT: BIOL ABS. RRM JOURNAL ARTICLE SOIL POLLUTION SOIL QUALITY SOIL CHEMISTRY AGRICULTURE ENVIRONMENT
1386178,Wilde and  Benemann 1993,BIOREMOVAL OF HEAVY METALS BY THE USE OF MICROALGAE,BIOSIS COPYRIGHT: BIOL ABS. RRM REVIEW ALGAE POLLUTION CONTROL WASTEWATER TREATMENT METHODS WASTE DISPOSAL WATER POLLUTION BIOTECHNOLOGY INDUSTRY BIOMASS,BIOREMOVAL OF HEAVY METALS BY THE USE OF MICROALGAE Abs: BIOSIS COPYRIGHT: BIOL ABS. RRM REVIEW ALGAE POLLUTION CONTROL WASTEWATER TREATMENT METHODS WASTE DISPOSAL WATER POLLUTION BIOTECHNOLOGY INDUSTRY BIOMASS
1386144,Goo 1993,MEASUREMENT OF POLLUTANTS MONITORING SAMPLING AND AUTOMATED ANALYSIS,BIOSIS COPYRIGHT: BIOL ABS. RRM REVIEW WASTEWATER TREATMENT ENVIRONMENTAL MONITORING EFFLUENT WATER POLLUTION CONTROL AUTOMATION PESTICIDE SCREENING ANALYTICAL METHODS,MEASUREMENT OF POLLUTANTS MONITORING SAMPLING AND AUTOMATED ANALYSIS Abs: BIOSIS COPYRIGHT: BIOL ABS. RRM REVIEW WASTEWATER TREATMENT ENVIRONMENTAL MONITORING EFFLUENT WATER POLLUTION CONTROL AUTOMATION PESTICIDE SCREENING ANALYTICAL METHODS
1386142,Enzminger 1993,INDUSTRIAL WASTES METAL FINISHING AND PROCESSING,BIOSIS COPYRIGHT: BIOL ABS. RRM REVIEW WASTE MANAGEMENT POLLUTION CONTROL HEAVY METALS REGULATION WASTE MINIMIZATION RECYCLING,INDUSTRIAL WASTES METAL FINISHING AND PROCESSING Abs: BIOSIS COPYRIGHT: BIOL ABS. RRM REVIEW WASTE MANAGEMENT POLLUTION CONTROL HEAVY METALS REGULATION WASTE MINIMIZATION RECYCLING
1386108,Lewtas 1993,AIRBORNE CARCINOGENS,BIOSIS COPYRIGHT: BIOL ABS. RRM HUMAN POLLUTION INORGANICS HYDROCARBONS ETHERS ALCOHOLS KETONES ALDEHYDES CARBOXYLIC ACIDS HETEROCYCLIC OXYGEN COMPOUNDS NITROGEN SULFUR HALOGEN-CONTAINING ORGANICS ORGANOMETALLIC COMPOUNDS,AIRBORNE CARCINOGENS Abs: BIOSIS COPYRIGHT: BIOL ABS. RRM HUMAN POLLUTION INORGANICS HYDROCARBONS ETHERS ALCOHOLS KETONES ALDEHYDES CARBOXYLIC ACIDS HETEROCYCLIC OXYGEN COMPOUNDS NITROGEN SULFUR HALOGEN-CONTAINING ORGANICS ORGANOMETALLIC COMPOUNDS
1386034,Vineis and  Blair 1992,Problems and perspectives in the identification of new occupational carcinogens,"BIOSIS COPYRIGHT: BIOL ABS. Occupational studies have played a major role in the identification of chemical carcinogens. There still remain, however, substances and occupations that deserve further evaluation. The more careful control of potentially hazardous exposures in most developed countries has necessitated a change in the conduct of epidemiologic investigations. The lowering of exposures and the lack of a simple correspondence between specific exposures and one or a few jobs underscores the need for careful reconstruction of historical exposures. The most successful reconstructions will include the integration of monitoring data, historical information on work histories and work practices, and use of biochemical markers.","Problems and perspectives in the identification of new occupational carcinogens Abs: BIOSIS COPYRIGHT: BIOL ABS. Occupational studies have played a major role in the identification of chemical carcinogens. There still remain, however, substances and occupations that deserve further evaluation. The more careful control of potentially hazardous exposures in most developed countries has necessitated a change in the conduct of epidemiologic investigations. The lowering of exposures and the lack of a simple correspondence between specific exposures and one or a few jobs underscores the need for careful reconstruction of historical exposures. The most successful reconstructions will include the integration of monitoring data, historical information on work histories and work practices, and use of biochemical markers."
1385990,Liu et al. 1992,Study of prediction for groundwater contamination in wastewater land treatment system,"BIOSIS COPYRIGHT: BIOL ABS. This paper uses a prediction model of groundwater pollution based on the experiments in the laboratory and in field. The model, which was tested and calibrated by the field observated data, satisfactorily simulated the field conditions in land treatment system of wastewater. Particularly, the model can provide the reliable pollution prediction of heavy metals, organisms and nitrogen. The model was used to predict the groundwater pollution caused by the land treatment system in the region of North China. The calibration of the model showed that correlation coefficients between the tested and predictive data of Cr6+. As 3+, organisms and NH+, could reach 0.990, which proved that the model possessed the realistic instructive significance for design and use of wastewater land treatment systems.","Study of prediction for groundwater contamination in wastewater land treatment system Abs: BIOSIS COPYRIGHT: BIOL ABS. This paper uses a prediction model of groundwater pollution based on the experiments in the laboratory and in field. The model, which was tested and calibrated by the field observated data, satisfactorily simulated the field conditions in land treatment system of wastewater. Particularly, the model can provide the reliable pollution prediction of heavy metals, organisms and nitrogen. The model was used to predict the groundwater pollution caused by the land treatment system in the region of North China. The calibration of the model showed that correlation coefficients between the tested and predictive data of Cr6+. As 3+, organisms and NH+, could reach 0.990, which proved that the model possessed the realistic instructive significance for design and use of wastewater land treatment systems."
1384996,Caldwell et al. 1999,Effect of curing on field-solidified waste properties. Part 2: Chemical properties,"BIOSIS COPYRIGHT: BIOL ABS. Differences that develop over time as a result of laboratory and field curing conditions in the chemical nature of monolithic waste samples are assessed in this paper. During field placement of waste treated using stabilization/solidification, a number of sub-samples were taken and cured under laboratory conditions. These samples were evaluated periodically using a battery of laboratory test methods in parallel with samples removed from the landfill by diamond core. The results indicate that, al","Effect of curing on field-solidified waste properties. Part 2: Chemical properties Abs: BIOSIS COPYRIGHT: BIOL ABS. Differences that develop over time as a result of laboratory and field curing conditions in the chemical nature of monolithic waste samples are assessed in this paper. During field placement of waste treated using stabilization/solidification, a number of sub-samples were taken and cured under laboratory conditions. These samples were evaluated periodically using a battery of laboratory test methods in parallel with samples removed from the landfill by diamond core. The results indicate that, al"
1384194,Kjaerheim 1999,Occupational cancer research in the Nordic countries,"BIOSIS COPYRIGHT: BIOL ABS. Occupational cancer research in the Nordic countries benefits from certain structural advantages, including the existence of computerized population registries, national cancer registries with high-quality data on cancer incidence, and a personal identification number for each inhabitant. This article outlines the utilization of this research infrastructure in Denmark, Finland, Iceland, Norway, and Sweden, together with research examples from the different countries. Future research on occupatio nt data sources together. Although previous occupational research has focused on male workers, a broader approach is needed in the future, including a study of how cancer risk in women may be affected by occupational activity and the question of possible cancer risk in offspring of men and women exposed to workplace carcinogens.","Occupational cancer research in the Nordic countries Abs: BIOSIS COPYRIGHT: BIOL ABS. Occupational cancer research in the Nordic countries benefits from certain structural advantages, including the existence of computerized population registries, national cancer registries with high-quality data on cancer incidence, and a personal identification number for each inhabitant. This article outlines the utilization of this research infrastructure in Denmark, Finland, Iceland, Norway, and Sweden, together with research examples from the different countries. Future research on occupatio nt data sources together. Although previous occupational research has focused on male workers, a broader approach is needed in the future, including a study of how cancer risk in women may be affected by occupational activity and the question of possible cancer risk in offspring of men and women exposed to workplace carcinogens."
1384173,Coggon 1999,Occupational cancer in the United Kingdom,"BIOSIS COPYRIGHT: BIOL ABS. Most of the known occupational hazards of cancer have occurred in the United Kingdom. Over recent decades a contraction of manufacturing industry and legal controls on carcinogens have led to reductions in exposure, but cases continue to occur, often as a consequence of exposures 20 or more years ago. By far the most important occupational cause of cancer in the United Kingdom is asbestos, which currently accounts for some 600 cases of mesothelioma and perhaps 100 cases of bronchial carcinoma pe zards of cancer are unlikely to account for more than 100 cases per year in total.","Occupational cancer in the United Kingdom Abs: BIOSIS COPYRIGHT: BIOL ABS. Most of the known occupational hazards of cancer have occurred in the United Kingdom. Over recent decades a contraction of manufacturing industry and legal controls on carcinogens have led to reductions in exposure, but cases continue to occur, often as a consequence of exposures 20 or more years ago. By far the most important occupational cause of cancer in the United Kingdom is asbestos, which currently accounts for some 600 cases of mesothelioma and perhaps 100 cases of bronchial carcinoma pe zards of cancer are unlikely to account for more than 100 cases per year in total."
1383534,Sikovec et al. 1996,Thermal Lens Spectrometric Determination of Hexavalent Chromium,"The objective of this work was to validate the thermal lens spectrometry (TLS) technique for the determination of hexavalent chromium (7440473) (Cr(VI)) by comparison of TLS results on realistic samples with results obtained by atomic absorption spectrometry (AAS) and by determination of Cr(VI) in standard reference water samples. TLS analysis was carried out of water samples and chromium/copper/arsenic (CCA) treated construction timbers, and by comparison of results to reported values or results obtained by atomic absorption spectrometry that thermal lens spectrometry is a reliable and accurate analytical technique for determining Cr(VI) in environmental samples such as wood and water. The limit of detection of 0.1 microgram/liter for water samples confirmed TLS as a highly sensitive technique providing by over an order of magnitude lower limits of detection compared to spectrophotometry and limits of detection comparable to non species specific techniques. The measurement of the chromium 1,5-diphenylcarbazide (DPC) chromophore provides sufficient selectivity for the described method. Ions generally known to interfere with the chromium reaction when present at higher concentrations were not important in the case of these samples.","Thermal Lens Spectrometric Determination of Hexavalent Chromium Abs: The objective of this work was to validate the thermal lens spectrometry (TLS) technique for the determination of hexavalent chromium (7440473) (Cr(VI)) by comparison of TLS results on realistic samples with results obtained by atomic absorption spectrometry (AAS) and by determination of Cr(VI) in standard reference water samples. TLS analysis was carried out of water samples and chromium/copper/arsenic (CCA) treated construction timbers, and by comparison of results to reported values or results obtained by atomic absorption spectrometry that thermal lens spectrometry is a reliable and accurate analytical technique for determining Cr(VI) in environmental samples such as wood and water. The limit of detection of 0.1 microgram/liter for water samples confirmed TLS as a highly sensitive technique providing by over an order of magnitude lower limits of detection compared to spectrophotometry and limits of detection comparable to non species specific techniques. The measurement of the chromium 1,5-diphenylcarbazide (DPC) chromophore provides sufficient selectivity for the described method. Ions generally known to interfere with the chromium reaction when present at higher concentrations were not important in the case of these samples."
1380332,Hartwell et al. 1989,TOXICITY VERSUS AVOIDANCE RESPONSE OF GOLDEN SHINER NOTEMIGONUS-CRYSOLEUCAS TO FIVE METALS,BIOSIS COPYRIGHT: BIOL ABS. RRM WATER POLLUTION CHROMIUM COPPER CADMIUM ARSENIC SELENIUM,TOXICITY VERSUS AVOIDANCE RESPONSE OF GOLDEN SHINER NOTEMIGONUS-CRYSOLEUCAS TO FIVE METALS Abs: BIOSIS COPYRIGHT: BIOL ABS. RRM WATER POLLUTION CHROMIUM COPPER CADMIUM ARSENIC SELENIUM
1379467,Eum et al. 1997,Development of analytical techniques for water and environmental samples (1),"The purpose of this study is to develop new analytical methods and to improve detection limit for inorganic elements and organic compounds in environmental samples. The results obtained in the first year of this project for As, Cr, VOCs, particulate materials in environmental samples using several methods such as ICP-MS, FI-AAS, Ion Chromatography, Flow FFF (Flow Field-Flow Fractionation) are as follows. Detection limit of Arsenic by ICP-MS is 0.017 ng/ml chloride-free samples. If chloride ion exist in samples (sup 35)Cl ion combines with (sup 40)Ar ion and conform (sup 40)Ar-(sup 35)Cl ion. (sup 40)Ar- (sup 35)Cl ion effects directly to (sup 75)As concentration in ICP-MS analysis because (sup 40)Ar-(sup 35)Cl is same mass with (sup 75)As. Removal of chloride ion is required to analyze ultratrace level of As by ICP-MS. In this experiment, chloride ion is removed with using Ag-cartridge. On the other hand, as time was passed from the date of preparing arsenic standard solutions, the measurement was detected at lower values by FI-AAS. Different separation- detection methods, viz., KSE widely performed in domestic method and EPA 218.6 method using ion chromatography were compared for the analysis of Cr(sup 6+) in reagent water, ground water, and real wastewater. The study found that EPA method 218.6 was shown to be accurate and precise for hexavalent chromium in waters of various matrices. The stability of Cr(sup 6+) was studied in waters with respect to pH and matrix. The evaluation of the results obtained was that long time. The TCLP(Toxicity Characteristic Leaching Procedure) designed by US EPA applied to determine especially volatile organic analytes in liquid and multiphasic wastes. Results represented showed that TCLP using zero-headspace extraction vessel could be recommended to analysis of volatile organic analytes in point of accuracy, lower detection limit, and reproducibility. A channel and main system of Flow FFF was set up for the purpose of the analysis of particulate materials in water and environmental samples. (author). 49 refs., 24 tabs., 15 figs.","Development of analytical techniques for water and environmental samples (1) Abs: The purpose of this study is to develop new analytical methods and to improve detection limit for inorganic elements and organic compounds in environmental samples. The results obtained in the first year of this project for As, Cr, VOCs, particulate materials in environmental samples using several methods such as ICP-MS, FI-AAS, Ion Chromatography, Flow FFF (Flow Field-Flow Fractionation) are as follows. Detection limit of Arsenic by ICP-MS is 0.017 ng/ml chloride-free samples. If chloride ion exist in samples (sup 35)Cl ion combines with (sup 40)Ar ion and conform (sup 40)Ar-(sup 35)Cl ion. (sup 40)Ar- (sup 35)Cl ion effects directly to (sup 75)As concentration in ICP-MS analysis because (sup 40)Ar-(sup 35)Cl is same mass with (sup 75)As. Removal of chloride ion is required to analyze ultratrace level of As by ICP-MS. In this experiment, chloride ion is removed with using Ag-cartridge. On the other hand, as time was passed from the date of preparing arsenic standard solutions, the measurement was detected at lower values by FI-AAS. Different separation- detection methods, viz., KSE widely performed in domestic method and EPA 218.6 method using ion chromatography were compared for the analysis of Cr(sup 6+) in reagent water, ground water, and real wastewater. The study found that EPA method 218.6 was shown to be accurate and precise for hexavalent chromium in waters of various matrices. The stability of Cr(sup 6+) was studied in waters with respect to pH and matrix. The evaluation of the results obtained was that long time. The TCLP(Toxicity Characteristic Leaching Procedure) designed by US EPA applied to determine especially volatile organic analytes in liquid and multiphasic wastes. Results represented showed that TCLP using zero-headspace extraction vessel could be recommended to analysis of volatile organic analytes in point of accuracy, lower detection limit, and reproducibility. A channel and main system of Flow FFF was set up for the purpose of the analysis of particulate materials in water and environmental samples. (author). 49 refs., 24 tabs., 15 figs."
1378905,Pantsar-Kallio and  Manninen P 1997,Simultaneous determination of toxic arsenic and chromium species in water samples by ion chromatography-inductively coupled plasma mass spectrometry,"BIOSIS COPYRIGHT: BIOL ABS. A method based on ion chromatography in conjunction with inductively coupled plasma mass spectrometry is presented for simultaneous determination of toxic chromium and arsenic species: Cr(VI), As(III) and As(V) using KNO3 at pH 9.8 as eluent. Cr(III), dimethylarsinate, monomethylarsonate, arsenobetaine and arsenocholine did not interfere with the analysis, since Cr(III) was eliminated before analysis and As species were separated from the analytes. The advantages and disadvantages of gradient and isocratic elution in trace speciation analysis by ion chromatography are discussed. With the method described, Cr(VI), As(III) and As(V) could be analyzed at a concentration level of 0.5 mug/l. An application of the proposed method is presented for waste water and drinking water analysis.","Simultaneous determination of toxic arsenic and chromium species in water samples by ion chromatography-inductively coupled plasma mass spectrometry Abs: BIOSIS COPYRIGHT: BIOL ABS. A method based on ion chromatography in conjunction with inductively coupled plasma mass spectrometry is presented for simultaneous determination of toxic chromium and arsenic species: Cr(VI), As(III) and As(V) using KNO3 at pH 9.8 as eluent. Cr(III), dimethylarsinate, monomethylarsonate, arsenobetaine and arsenocholine did not interfere with the analysis, since Cr(III) was eliminated before analysis and As species were separated from the analytes. The advantages and disadvantages of gradient and isocratic elution in trace speciation analysis by ion chromatography are discussed. With the method described, Cr(VI), As(III) and As(V) could be analyzed at a concentration level of 0.5 mug/l. An application of the proposed method is presented for waste water and drinking water analysis."
1376156,Vainio and  Hemminki 1991,Use of exposure information and animal cancer data in the prevention of environmental and occupational cancer,"In order to prevent cancer, a hazard should optimally be identified before humans are exposed to it. Therefore, valid procedures should be available for predicting human risks on the basis of experimental results. The adequacy of experimental data for identifying potential human health risks have been the subject of scientific question and debate. Use of such results and of data on exposure in setting priorities for cancer prevention should, in principle, be feasible in view of the relatively good correlation between animal and human data. Studies have also revealed a reasonable quantitative relationship between carcinogenic potencies of several chemicals in laboratory rodents and humans. The ranking of cancer hazards on the basis of experimental data requires estimates of both the extent of human exposure and of the size of the exposed population. Occupational exposures can result in high individual exposures, whereas the general population is usually exposed to lower levels. Action for cancer prevention can be taken at both levels.","Use of exposure information and animal cancer data in the prevention of environmental and occupational cancer Abs: In order to prevent cancer, a hazard should optimally be identified before humans are exposed to it. Therefore, valid procedures should be available for predicting human risks on the basis of experimental results. The adequacy of experimental data for identifying potential human health risks have been the subject of scientific question and debate. Use of such results and of data on exposure in setting priorities for cancer prevention should, in principle, be feasible in view of the relatively good correlation between animal and human data. Studies have also revealed a reasonable quantitative relationship between carcinogenic potencies of several chemicals in laboratory rodents and humans. The ranking of cancer hazards on the basis of experimental data requires estimates of both the extent of human exposure and of the size of the exposed population. Occupational exposures can result in high individual exposures, whereas the general population is usually exposed to lower levels. Action for cancer prevention can be taken at both levels."
1376155,Kroes and  Kramers P 1991,ENVIRONMENT CHEMICALS AND PUBLIC HEALTH,BIOSIS COPYRIGHT: BIOL ABS. RRM HUMAN POLLUTION CANCER,ENVIRONMENT CHEMICALS AND PUBLIC HEALTH Abs: BIOSIS COPYRIGHT: BIOL ABS. RRM HUMAN POLLUTION CANCER
1375988,Wasay 1992,"Leaching behaviour of trace toxic metals from flyash, their seepage control to groundwater and utilisation of flyash","BIOSIS COPYRIGHT: BIOL ABS. The flyash of coal based thermal power plants is being dumped openly from the last several years in the form of wet slurry in a pond where leaching of trace toxic metals contaminate both surface and groundwater. The leaching characteristics of chromium (III), chromium (VI), mercury (II) and arsenic from flyash were investigated at various pH levels. It was estimated at pH 7.0 that about 40% of these toxic elements present in flyash was leachatable and many leach out to groundwater. Twelve monitoring wells were selected surrounding the dumping site for studying these metals in groundwater. The ash transport water samples of the pond were also examined for these toxic metals. PH of both surface and groundwater were measured measured and found in the range of 6.5 to 7.8. The concentration of these toxic metals in groundwater around the dumping site as well as in ash transport water samples were determined by grafite AAS and Sp-500 spectrophotometric methods and the results","Leaching behaviour of trace toxic metals from flyash, their seepage control to groundwater and utilisation of flyash Abs: BIOSIS COPYRIGHT: BIOL ABS. The flyash of coal based thermal power plants is being dumped openly from the last several years in the form of wet slurry in a pond where leaching of trace toxic metals contaminate both surface and groundwater. The leaching characteristics of chromium (III), chromium (VI), mercury (II) and arsenic from flyash were investigated at various pH levels. It was estimated at pH 7.0 that about 40% of these toxic elements present in flyash was leachatable and many leach out to groundwater. Twelve monitoring wells were selected surrounding the dumping site for studying these metals in groundwater. The ash transport water samples of the pond were also examined for these toxic metals. PH of both surface and groundwater were measured measured and found in the range of 6.5 to 7.8. The concentration of these toxic metals in groundwater around the dumping site as well as in ash transport water samples were determined by grafite AAS and Sp-500 spectrophotometric methods and the results"
1372966,Nygren and  Nilsson 1993,"Determination and speciation of chromium, copper and arsenic in wood and dust from CCA-impregnated timber","BIOSIS COPYRIGHT: BIOL ABS. Copper, chromium and arsenic are frequently used in preservatives for impregnantion of timber (CCA preservatives). These contain the more toxic forms, hexavalent chromium and trivalent arsenic. Speciation of these elemental forms is therefore essential for quality control of impregnation and for the safety of the work environment during impregnation of timber and in places where such timber is used. Methods for determination of copper, chromium and arsenic and for speciation of hexalvent chromium, tri- and pentavalent arsenic are presented and examples given of the determination of these compounds in wood and dust from impregnated timber. The level of preservative in wood purchased from ten retailers was 1.5-3%. No trivalent arsenic was found, but up to 20% of the chromium present was hexalvalent. This shows that impregnated timber with improperly fixed preservative is present on the market. Such timber can cause hazardous occupational exposure and may also confer reduce","Determination and speciation of chromium, copper and arsenic in wood and dust from CCA-impregnated timber Abs: BIOSIS COPYRIGHT: BIOL ABS. Copper, chromium and arsenic are frequently used in preservatives for impregnantion of timber (CCA preservatives). These contain the more toxic forms, hexavalent chromium and trivalent arsenic. Speciation of these elemental forms is therefore essential for quality control of impregnation and for the safety of the work environment during impregnation of timber and in places where such timber is used. Methods for determination of copper, chromium and arsenic and for speciation of hexalvent chromium, tri- and pentavalent arsenic are presented and examples given of the determination of these compounds in wood and dust from impregnated timber. The level of preservative in wood purchased from ten retailers was 1.5-3%. No trivalent arsenic was found, but up to 20% of the chromium present was hexalvalent. This shows that impregnated timber with improperly fixed preservative is present on the market. Such timber can cause hazardous occupational exposure and may also confer reduce"
1371581,Wolf et al. 2008,Speciation Methods Used to Assess Potential Health Effects of Toxic Metals in Environmental Materials,"Assessing potential exposures to toxic metals or metalloids such as arsenic and chromium in environmental materials is important in protecting public health. The chemical form of an element in, or released from, a material is also important, since some forms, such as Cr(VI), are more toxic than others, for example, Cr(III). We have used a variety of procedures to assess potential exposures to hexavalent chromium in ash and burned soils from October 2007 southern California wildfires. Synthetic lung-fluid and de-ionized water extractions simulate release in the lungs and potential environmental releases due to rainfall. Extracts were analyzed for specific chromium and arsenic species using HPLC-ICP-MS methodology. Results indicate that the highly oxidizing environment in wildfires promotes some chromium conversion to Cr(VI), and that the caustic alkalinity of ash enhances Cr(VI) release and stability in lung fluids and rainfall.","Speciation Methods Used to Assess Potential Health Effects of Toxic Metals in Environmental Materials Abs: Assessing potential exposures to toxic metals or metalloids such as arsenic and chromium in environmental materials is important in protecting public health. The chemical form of an element in, or released from, a material is also important, since some forms, such as Cr(VI), are more toxic than others, for example, Cr(III). We have used a variety of procedures to assess potential exposures to hexavalent chromium in ash and burned soils from October 2007 southern California wildfires. Synthetic lung-fluid and de-ionized water extractions simulate release in the lungs and potential environmental releases due to rainfall. Extracts were analyzed for specific chromium and arsenic species using HPLC-ICP-MS methodology. Results indicate that the highly oxidizing environment in wildfires promotes some chromium conversion to Cr(VI), and that the caustic alkalinity of ash enhances Cr(VI) release and stability in lung fluids and rainfall."
1366466,Beg and  Hassan 1987,EFFECTS OF INHIBITORS ON NITRIFICATION IN A PACKED-BED BIOLOGICAL FLOW REACTOR,BIOSIS COPYRIGHT: BIOL ABS. RRM ARSENIC-III CHROMIUM-VI FLUORIDE MODEL WASTEWATER TREATMENT,EFFECTS OF INHIBITORS ON NITRIFICATION IN A PACKED-BED BIOLOGICAL FLOW REACTOR Abs: BIOSIS COPYRIGHT: BIOL ABS. RRM ARSENIC-III CHROMIUM-VI FLUORIDE MODEL WASTEWATER TREATMENT
1366314,Welp 1999,Inhibitory effects of the total and water-soluble concentrations of nine different metals on the dehydrogenase activity of a loess soil,"BIOSIS COPYRIGHT: BIOL ABS. This study focuses on a comparison of the microbial toxicity of nine metals, including As as a metalloid and two species of Cr. A loess soil (Ap horizon, clay 15.2%, organic C 1.12%, pH(CaCl2) 7.02) was spiked with 8-12 geometrically increasing doses of the metals. The dehydrogenase assay (2-p-iodophenyl-3-p-nitrophenyl-5-phenyltetrazoliumchloride method) was combined with sorption and solubility experiments. The resulting dose-response curves and sorption isotherms were used to derive total doses that caused definite percentage inhibitions (i.e. effective doses (ED) causing a 10-90% reduction in dehydrogenase activity (dha)) as well as the corresponding toxic solution concentrations causing the same reductions in dha (i.e. effective concentrations; EC10-EC90). Based on total doses, the toxicity decreased in the following order with ED50 values (mg kg-1) given in brackets: Hg (2.0) Cu (35) Cr(VI) (71) Cr(III) (75) Cd (90) Ni (100) Zn (115) As (168) Co (582) Pb (652). With regard to solution concentrations, toxicity decreased in the order (EC50 in mg l-1): Hg (0.003) Pb (0.04) Cu (0.05) Cd (0.14) Zn (0.19) Cr(III) (0.62) Ni (0.69) Co (30.6) As (55.5) Cr(VI) (78.1). The retention of the metals by the soil differed strongly. Pb, Cu, and Hg exhibited the highest and Ni, As, and Cr(VI) the lowest sorption constants (Freundlich K values: 2455, 724, 348, 93, 13, and 0.06 mg kg-1, respectively). The sorptivity of the metals and their microbial toxicity in the aqueous phase were characteristically related: metals with a strong toxic action in the soil solution were adsorbed by the soil to a high degree and vice versa. Therefore, especially for metals with a high inherent toxicity, sorption is an effective way of immobilizing them and temporari ly detoxifying soil.","Inhibitory effects of the total and water-soluble concentrations of nine different metals on the dehydrogenase activity of a loess soil Abs: BIOSIS COPYRIGHT: BIOL ABS. This study focuses on a comparison of the microbial toxicity of nine metals, including As as a metalloid and two species of Cr. A loess soil (Ap horizon, clay 15.2%, organic C 1.12%, pH(CaCl2) 7.02) was spiked with 8-12 geometrically increasing doses of the metals. The dehydrogenase assay (2-p-iodophenyl-3-p-nitrophenyl-5-phenyltetrazoliumchloride method) was combined with sorption and solubility experiments. The resulting dose-response curves and sorption isotherms were used to derive total doses that caused definite percentage inhibitions (i.e. effective doses (ED) causing a 10-90% reduction in dehydrogenase activity (dha)) as well as the corresponding toxic solution concentrations causing the same reductions in dha (i.e. effective concentrations; EC10-EC90). Based on total doses, the toxicity decreased in the following order with ED50 values (mg kg-1) given in brackets: Hg (2.0) Cu (35) Cr(VI) (71) Cr(III) (75) Cd (90) Ni (100) Zn (115) As (168) Co (582) Pb (652). With regard to solution concentrations, toxicity decreased in the order (EC50 in mg l-1): Hg (0.003) Pb (0.04) Cu (0.05) Cd (0.14) Zn (0.19) Cr(III) (0.62) Ni (0.69) Co (30.6) As (55.5) Cr(VI) (78.1). The retention of the metals by the soil differed strongly. Pb, Cu, and Hg exhibited the highest and Ni, As, and Cr(VI) the lowest sorption constants (Freundlich K values: 2455, 724, 348, 93, 13, and 0.06 mg kg-1, respectively). The sorptivity of the metals and their microbial toxicity in the aqueous phase were characteristically related: metals with a strong toxic action in the soil solution were adsorbed by the soil to a high degree and vice versa. Therefore, especially for metals with a high inherent toxicity, sorption is an effective way of immobilizing them and temporari ly detoxifying soil."
1366127,Bode 1998,Control of heavy metal emission from metal plating industry in a German river basin,BIOSIS COPYRIGHT: BIOL ABS. The introduction of clear limits for the indirect discharge of heavy metals in Germany has greatly reduced the emissions from metal plating industry. Despite the more than 500 metal plating workshops within the Ruhr catchment area the current requirements for water quality of riverwater am met in the Ruhr (even the German limit values for drinking water are met). Nevertheless the industrial emissions into the sewers are still above the permitted level and above what routine checks of the industrial effluents lead to believe. Thus with respect to the German wastewater sludge regulation half of the dry sludge solids must be excluded from agricultural use. The complete implementation of legal requirements by all workshops will further diminish the heavy metal emissions into wastewater sludge and receiving waters.,Control of heavy metal emission from metal plating industry in a German river basin Abs: BIOSIS COPYRIGHT: BIOL ABS. The introduction of clear limits for the indirect discharge of heavy metals in Germany has greatly reduced the emissions from metal plating industry. Despite the more than 500 metal plating workshops within the Ruhr catchment area the current requirements for water quality of riverwater am met in the Ruhr (even the German limit values for drinking water are met). Nevertheless the industrial emissions into the sewers are still above the permitted level and above what routine checks of the industrial effluents lead to believe. Thus with respect to the German wastewater sludge regulation half of the dry sludge solids must be excluded from agricultural use. The complete implementation of legal requirements by all workshops will further diminish the heavy metal emissions into wastewater sludge and receiving waters.
1366115,Terzaghi et al. 1998,Physical-chemical and ecotoxicological evaluation of water based drilling fluids used in Italian off-shore activities,"BIOSIS COPYRIGHT: BIOL ABS. In order to evaluate the effects on the marine ecosystem caused by an eventual discharge into sea of water based drilling fluids, as current legislation allows, chemical and ecotoxicological analyses were performed on the most common drilling muds and products used in Italian off-shore activities. The chemical analysis on drilling fluids involved the leaching test and the measurement of total content of heavy metals, whereas biodegradation tests were performed on the products used in mud's formulations. As for ecotoxicological evaluation, two marine organisms, the crustacean Artemia salina and the diatom Phaeodactylum tricornutum, were selected to determine the LC50 and the EC50 respectively.","Physical-chemical and ecotoxicological evaluation of water based drilling fluids used in Italian off-shore activities Abs: BIOSIS COPYRIGHT: BIOL ABS. In order to evaluate the effects on the marine ecosystem caused by an eventual discharge into sea of water based drilling fluids, as current legislation allows, chemical and ecotoxicological analyses were performed on the most common drilling muds and products used in Italian off-shore activities. The chemical analysis on drilling fluids involved the leaching test and the measurement of total content of heavy metals, whereas biodegradation tests were performed on the products used in mud's formulations. As for ecotoxicological evaluation, two marine organisms, the crustacean Artemia salina and the diatom Phaeodactylum tricornutum, were selected to determine the LC50 and the EC50 respectively."
1358896,Martin et al. 1981,Toxicities of 10 metals to Crassostrea gigas and Mytilus edulis embryos and Cancer magister larvae,"HEEP COPYRIGHT: BIOL ABS. Pacific oyster (C. gigas) embryos, bay mussel (M. edulis) embryos and Dungeness crab (C. magister) zoea I stage larvae were exposed to As, Cd, Cr, Cu, Pb, Hg, Ni, Se, Ag and Zn salts. The 2 bivalve species were exposed through the completion of embryogenesis (48 h) and the effects of the metals on abnormal development were monitored. The crab larval stages were exposed to the metal solutions for 96 h. Concentrations (mug/l) which caused 50% abnormal development in the 2 spp. of bivalve larvae and LC50 of the crab larvae ranged from 5.3 (oyster) to 49 (crab) for Cu; 5.8 (mussel) to 8.2 (crab) for Hg; 14 (mussel) to 55 (crab) for Ag; 119 (oyster) to 456 (crab) for Zn; 232 (crab) to 3000 (mussel) for As; 247 (crab) to 1200 (mussel) for Cd; 349 (oyster) to 4360 (crab) for Ni; 476 (mussel) to 758 (oyster) for Pb; 3440 (crab) to 4538 (oyster) for Cr6+; and Se 10,000 for the 3 spp. The acute toxicity testing of C. gigas embryo with 2 California (USA) native species confirmed its usefulness for predicting toxicity to the latter species.","Toxicities of 10 metals to Crassostrea gigas and Mytilus edulis embryos and Cancer magister larvae Abs: HEEP COPYRIGHT: BIOL ABS. Pacific oyster (C. gigas) embryos, bay mussel (M. edulis) embryos and Dungeness crab (C. magister) zoea I stage larvae were exposed to As, Cd, Cr, Cu, Pb, Hg, Ni, Se, Ag and Zn salts. The 2 bivalve species were exposed through the completion of embryogenesis (48 h) and the effects of the metals on abnormal development were monitored. The crab larval stages were exposed to the metal solutions for 96 h. Concentrations (mug/l) which caused 50% abnormal development in the 2 spp. of bivalve larvae and LC50 of the crab larvae ranged from 5.3 (oyster) to 49 (crab) for Cu; 5.8 (mussel) to 8.2 (crab) for Hg; 14 (mussel) to 55 (crab) for Ag; 119 (oyster) to 456 (crab) for Zn; 232 (crab) to 3000 (mussel) for As; 247 (crab) to 1200 (mussel) for Cd; 349 (oyster) to 4360 (crab) for Ni; 476 (mussel) to 758 (oyster) for Pb; 3440 (crab) to 4538 (oyster) for Cr6+; and Se 10,000 for the 3 spp. The acute toxicity testing of C. gigas embryo with 2 California (USA) native species confirmed its usefulness for predicting toxicity to the latter species."
1358163,Fischmann et al. 1979,"Exposure To Chemicals, Physical Agents, And Biologic Agents In Mycosis Fungoides And The Sezary Syndrome","Environmental and host factors among patients with mycosis fungoides or cutaneous T-cell lymphoma were investigated. The study involved 44 patients treated at the National Cancer Institute, Veterans' Administration Medical Oncology Branch. Patients underwent routine pretreatment staging procedures including a complete physical examination and biopsies of the skin, lymph nodes, bone marrow, and liver. Forty of the patients were exposed to at least one chemical and the mean duration of exposure was 13 years. Thirty eight stated they had some drug exposure. Exposure ranged from 2 to 48 years. The four most common drugs were tobacco, analgesics, tranquilizers, and thiazide (58946) diuretics. Exposure to chemicals included benzopyrene (73467762), polycyclic aromatic hydrocarbons, carbon-tetrachloride (56235), DDT (50293), chromium (18540299), lead (7439921), arsenic (7440382), asbestos (1332214), and creosote (8001589). In three of the cases, the disease began with a drug reaction after which the skin never cleared. Twenty four of the 28 patients questioned smoked. The mean duration of smoking was 24 years with a mean of 25 cigarettes per day. Recurrent herpes simplex occurred in 14 of 22 patients questioned. Eleven of the patients had a family history of carcinoma. The authors conclude that patients with chronic skin disease are candidates for developing mycosis fungoides, especially if they show long term chemical or drug exposure, heavy smoking, or recurrent herpes simplex.","Exposure To Chemicals, Physical Agents, And Biologic Agents In Mycosis Fungoides And The Sezary Syndrome Abs: Environmental and host factors among patients with mycosis fungoides or cutaneous T-cell lymphoma were investigated. The study involved 44 patients treated at the National Cancer Institute, Veterans' Administration Medical Oncology Branch. Patients underwent routine pretreatment staging procedures including a complete physical examination and biopsies of the skin, lymph nodes, bone marrow, and liver. Forty of the patients were exposed to at least one chemical and the mean duration of exposure was 13 years. Thirty eight stated they had some drug exposure. Exposure ranged from 2 to 48 years. The four most common drugs were tobacco, analgesics, tranquilizers, and thiazide (58946) diuretics. Exposure to chemicals included benzopyrene (73467762), polycyclic aromatic hydrocarbons, carbon-tetrachloride (56235), DDT (50293), chromium (18540299), lead (7439921), arsenic (7440382), asbestos (1332214), and creosote (8001589). In three of the cases, the disease began with a drug reaction after which the skin never cleared. Twenty four of the 28 patients questioned smoked. The mean duration of smoking was 24 years with a mean of 25 cigarettes per day. Recurrent herpes simplex occurred in 14 of 22 patients questioned. Eleven of the patients had a family history of carcinoma. The authors conclude that patients with chronic skin disease are candidates for developing mycosis fungoides, especially if they show long term chemical or drug exposure, heavy smoking, or recurrent herpes simplex."
1357076,Dencker and  Danielsson 1987,Transfer of drugs to the embryo and fetus after placentation,BIOSIS COPYRIGHT: BIOL ABS. RRM HUMAN TOXICITY METALS ANESTHETIC GASES OCCUPATIONAL EXPOSURE,Transfer of drugs to the embryo and fetus after placentation Abs: BIOSIS COPYRIGHT: BIOL ABS. RRM HUMAN TOXICITY METALS ANESTHETIC GASES OCCUPATIONAL EXPOSURE
1356163,Versar 1987,1978 Cross sectional health study of workers at a wood preserving plant with attachments,,1978 Cross sectional health study of workers at a wood preserving plant with attachments Abs: 
1354301,Tomatis et al. 1997,Avoided and avoidable risks of cancer,"BIOSIS COPYRIGHT: BIOL ABS. Despite the considerable efforts and funds devoted to cancer research over several decades, cancer still remains a mainly lethal disease. Cancer incidence and mortality have not declined at the same rate as other major causes of death, indicating that primary prevention remains a most valuable approach to decrease mortality. There is general agreement that environmental exposures are variously involved in the causation of the majority of cancer cases and that at least half of all cancers could be avoided by applying existing etiologic knowledge. There is disagreement, however, regarding the proportion of cancer risks attributable to specific etiological factors, including diet, occupation and pollution. Estimates of attributable risks are largely based today on unverified assumptions and the calculation of attributable risks involves taking very unequal evidence of various types of factors and treating them equally. Effective primary prevention resulting in a reduction","Avoided and avoidable risks of cancer Abs: BIOSIS COPYRIGHT: BIOL ABS. Despite the considerable efforts and funds devoted to cancer research over several decades, cancer still remains a mainly lethal disease. Cancer incidence and mortality have not declined at the same rate as other major causes of death, indicating that primary prevention remains a most valuable approach to decrease mortality. There is general agreement that environmental exposures are variously involved in the causation of the majority of cancer cases and that at least half of all cancers could be avoided by applying existing etiologic knowledge. There is disagreement, however, regarding the proportion of cancer risks attributable to specific etiological factors, including diet, occupation and pollution. Estimates of attributable risks are largely based today on unverified assumptions and the calculation of attributable risks involves taking very unequal evidence of various types of factors and treating them equally. Effective primary prevention resulting in a reduction"
1353614,Song et al. 2006,Hexavalent chromium reduction in soils contaminated with chromated copper arsenate preservative,,Hexavalent chromium reduction in soils contaminated with chromated copper arsenate preservative Abs: 
1353189,Upreti et al. 2006,A comparative study on rat intestinal epithelial cells and resident gut bacteria (ii) effect of arsenite,"<strong>OBJECTIVE: </strong>In order to use facultative gut bacteria as an alternate to animals for the initial gastrointestinal toxicity screening of heavy metals, a comparative study on rat intestinal epithelial cells and resident gut bacteria was undertaken.<br /><br /><strong>METHODS: </strong>in vitro growth rate of four gut bacteria, dehydrogenase (DHA) and esterase (EA) activity test, intestinal epithelial and bacterial cell membrane enzymes and in situ effect of arsenite were analysed.<br /><br /><strong>RESULTS: </strong>Growth profile of mixed resident population of gut bacteria and pure isolates of Escherichia coli, Pseudomonas sp., Lactobacillus sp., and Staphylococcus sp. revealed an arsenite (2-20 ppm) concentration-dependent inhibition. The viability pattern of epithelial cells also showed similar changes. DHA and EA tests revealed significant inhibition (40%-72%) with arsenite exposure of 5 and 10 ppm in isolated gut bacteria and epithelial cells. Decrease in membrane alkaline phosphatase and Ca2+ -Mg2+ -ATPase activities was in the range of 33%-55% in four bacteria at the arsenite exposure of 10 ppm, whereas it was 60%-65% in intestinal epithelial villus cells. in situ incubation of arsenite using intestinal loops also showed more or less similar changes in membrane enzymes of resident gut bacterial population and epithelial cells.<br /><br /><strong>CONCLUSION: </strong>The results indicate that facultative gut bacteria can be used as suitable in vitro model for the preliminary screening of arsenical gastrointestinal cytotoxic effects.","A comparative study on rat intestinal epithelial cells and resident gut bacteria (ii) effect of arsenite Abs: <strong>OBJECTIVE: </strong>In order to use facultative gut bacteria as an alternate to animals for the initial gastrointestinal toxicity screening of heavy metals, a comparative study on rat intestinal epithelial cells and resident gut bacteria was undertaken.<br /><br /><strong>METHODS: </strong>in vitro growth rate of four gut bacteria, dehydrogenase (DHA) and esterase (EA) activity test, intestinal epithelial and bacterial cell membrane enzymes and in situ effect of arsenite were analysed.<br /><br /><strong>RESULTS: </strong>Growth profile of mixed resident population of gut bacteria and pure isolates of Escherichia coli, Pseudomonas sp., Lactobacillus sp., and Staphylococcus sp. revealed an arsenite (2-20 ppm) concentration-dependent inhibition. The viability pattern of epithelial cells also showed similar changes. DHA and EA tests revealed significant inhibition (40%-72%) with arsenite exposure of 5 and 10 ppm in isolated gut bacteria and epithelial cells. Decrease in membrane alkaline phosphatase and Ca2+ -Mg2+ -ATPase activities was in the range of 33%-55% in four bacteria at the arsenite exposure of 10 ppm, whereas it was 60%-65% in intestinal epithelial villus cells. in situ incubation of arsenite using intestinal loops also showed more or less similar changes in membrane enzymes of resident gut bacterial population and epithelial cells.<br /><br /><strong>CONCLUSION: </strong>The results indicate that facultative gut bacteria can be used as suitable in vitro model for the preliminary screening of arsenical gastrointestinal cytotoxic effects."
1352257,Riedel and  Sanders 1998,Trace element speciation and behavior in the tidal Delaware River,"BIOSIS COPYRIGHT: BIOL ABS. Measurements of dissolved As, Cr, Cu, and Se using species-selective techniques were made in the tidal freshwater Delaware River at four sites in July 199 1, January 1992, and March 1992. Concentrations of dissolved As, Cr, and Se were generally higher in July than in March or January. Copper concentrations were relatively constant. Both As and Co increased in concentration in the region of Philadelphia. Measurements of As, Cd, Cr, Cu, Pb, Ni, Se, and Zn in seston were made during the July 1991 and March 1992 sampling using both a total digest and a series of sequential leaches. A large fraction of most of the elements, in the order Cd Zn Pb \ Cu Ni \ As Cr Se, was solubilized by weak acid. The remaining fraction, for elements where the acid leach was not complete, was released by a rigorous digestion with concentrated acids. Based on estimates of similar rivers, Pb and Zn appear to be substantially enriched in Delaware River seston compared to","Trace element speciation and behavior in the tidal Delaware River Abs: BIOSIS COPYRIGHT: BIOL ABS. Measurements of dissolved As, Cr, Cu, and Se using species-selective techniques were made in the tidal freshwater Delaware River at four sites in July 199 1, January 1992, and March 1992. Concentrations of dissolved As, Cr, and Se were generally higher in July than in March or January. Copper concentrations were relatively constant. Both As and Co increased in concentration in the region of Philadelphia. Measurements of As, Cd, Cr, Cu, Pb, Ni, Se, and Zn in seston were made during the July 1991 and March 1992 sampling using both a total digest and a series of sequential leaches. A large fraction of most of the elements, in the order Cd Zn Pb \ Cu Ni \ As Cr Se, was solubilized by weak acid. The remaining fraction, for elements where the acid leach was not complete, was released by a rigorous digestion with concentrated acids. Based on estimates of similar rivers, Pb and Zn appear to be substantially enriched in Delaware River seston compared to"
1352059,Ramanathan et al. 1997,Bacterial biosensors for monitoring toxic metals,"BIOSIS COPYRIGHT: BIOL ABS. Biosensors utilize biological components to provide selectivity for monitoring compounds of environmental, clinical and industrial importance. A number of biosenors based on bacteria have recently been developed for monitoring toxic metals in the environment. The advantages and disadvantages of these types of biosensors are discussed.","Bacterial biosensors for monitoring toxic metals Abs: BIOSIS COPYRIGHT: BIOL ABS. Biosensors utilize biological components to provide selectivity for monitoring compounds of environmental, clinical and industrial importance. A number of biosenors based on bacteria have recently been developed for monitoring toxic metals in the environment. The advantages and disadvantages of these types of biosensors are discussed."
1351846,Prasad et al. 1996,Environmental assessment of coal ash disposal: A review,BIOSIS COPYRIGHT: BIOL ABS. RRM LITERATURE REVIEW COAL ASH DISPOSAL ENVIRONMENTAL ASSESSMENT GROUNDWATER CONTAMINATION SURFACE WATER CONTAMINATION HEAVY METAL IONS CONTAMINANT LEACHING WASTE MANAGEMENT,Environmental assessment of coal ash disposal: A review Abs: BIOSIS COPYRIGHT: BIOL ABS. RRM LITERATURE REVIEW COAL ASH DISPOSAL ENVIRONMENTAL ASSESSMENT GROUNDWATER CONTAMINATION SURFACE WATER CONTAMINATION HEAVY METAL IONS CONTAMINANT LEACHING WASTE MANAGEMENT
1351494,Pastorok et al. 1994,ECOLOGICAL RISK ASSESSMENT FOR RIVER SEDIMENTS CONTAMINATED BY CREOSOTE,"BIOSIS COPYRIGHT: BIOL ABS. An ecological risk assessment was conducted for sediments of the lower Willamette River near a wood-treatment (creosote) facility. Both surface and subsurface sediments near the facility are contaminated by polycyclic aromatic hydrocarbons (PAHs). Limited contamination of sediments by dioxins/furans, chlorinated phenols, and arsenic was also observed. Sediment bioassays based on amphipod (Hyalella azteca) mortality and Microtox (Photobacterium phosphoreum) bioluminescence showed toxicity within approximately 300 ft of the shoreline, with a highly toxic area (i.e., possible acute lethal effects in sedentary benthic species) near a dock used for creosote off-loading. The relatively low concentrations of contaminants measured in crayfish muscle tissue and the absence of serious lesions in livers of large-scale sucker collected near the site suggest that excess risk to mobile species from chronic contamination is low. Cursory observations indicate that acute toxic effects o","ECOLOGICAL RISK ASSESSMENT FOR RIVER SEDIMENTS CONTAMINATED BY CREOSOTE Abs: BIOSIS COPYRIGHT: BIOL ABS. An ecological risk assessment was conducted for sediments of the lower Willamette River near a wood-treatment (creosote) facility. Both surface and subsurface sediments near the facility are contaminated by polycyclic aromatic hydrocarbons (PAHs). Limited contamination of sediments by dioxins/furans, chlorinated phenols, and arsenic was also observed. Sediment bioassays based on amphipod (Hyalella azteca) mortality and Microtox (Photobacterium phosphoreum) bioluminescence showed toxicity within approximately 300 ft of the shoreline, with a highly toxic area (i.e., possible acute lethal effects in sedentary benthic species) near a dock used for creosote off-loading. The relatively low concentrations of contaminants measured in crayfish muscle tissue and the absence of serious lesions in livers of large-scale sucker collected near the site suggest that excess risk to mobile species from chronic contamination is low. Cursory observations indicate that acute toxic effects o"
1350633,Mukherjee et al. 1999,Protection by black tea extract against chromosome damage induced by two heavy metals in mice,,Protection by black tea extract against chromosome damage induced by two heavy metals in mice Abs: 
1349846,Majumdar et al. 2007,"Industrial processing of rice husk for environment, energy and economy","An approach for comprehensive and efficient utilization of Rice Husk (RH) integrating the three E's - Environment, Energy and Economy has been outlined based on experimental information. RH can be thermally processed for co-production of metal-impregnated or chemically modified active solid silica-carbon composites with simultaneous recovery of liquid and gaseous by-products accounting for about 80-90% of the biomass with minimum addition to environmental pollution. The active and amorphous silica-carbon composite solid can be used in systems for removing waterborne and airborne toxic substances like phenol, hexavalent chromium, fluoride and arsenic in water and vapours of acetone, chloroform, benzene and pyridine. Liquid condensate collected during processing is a rich source of various useful organic chemicals. The third bulk co-product, a combustible gas of low calorific value, can supplement the energy requirements of the process. The spent silicarbons, after use in pollution abatement systems may be suitably formulated and melted into stable glass thus solving one of the major problems of ultimate disposal of toxic-loaded solid wastes generated. Small industries handling similar to 60 MT RH annually appear to be just viable. AS ancillaries to rice mills they are likely to prove handsomely rewarding. Projected estimates further Indicate that industrial processing in the suggested mode, of only 10% of India's annual RH biomass (4 Million Metric Tons), has the potential of generating similar to 200000 employments in similar to 66000 small decentralised units. The estimated capital investment is in the order of Rs. 6600 crores.","Industrial processing of rice husk for environment, energy and economy Abs: An approach for comprehensive and efficient utilization of Rice Husk (RH) integrating the three E's - Environment, Energy and Economy has been outlined based on experimental information. RH can be thermally processed for co-production of metal-impregnated or chemically modified active solid silica-carbon composites with simultaneous recovery of liquid and gaseous by-products accounting for about 80-90% of the biomass with minimum addition to environmental pollution. The active and amorphous silica-carbon composite solid can be used in systems for removing waterborne and airborne toxic substances like phenol, hexavalent chromium, fluoride and arsenic in water and vapours of acetone, chloroform, benzene and pyridine. Liquid condensate collected during processing is a rich source of various useful organic chemicals. The third bulk co-product, a combustible gas of low calorific value, can supplement the energy requirements of the process. The spent silicarbons, after use in pollution abatement systems may be suitably formulated and melted into stable glass thus solving one of the major problems of ultimate disposal of toxic-loaded solid wastes generated. Small industries handling similar to 60 MT RH annually appear to be just viable. AS ancillaries to rice mills they are likely to prove handsomely rewarding. Projected estimates further Indicate that industrial processing in the suggested mode, of only 10% of India's annual RH biomass (4 Million Metric Tons), has the potential of generating similar to 200000 employments in similar to 66000 small decentralised units. The estimated capital investment is in the order of Rs. 6600 crores."
1349692,Lussier et al. 1999,Comparison of dissolved and total metals concentrations from acute tests with saltwater organisms,,Comparison of dissolved and total metals concentrations from acute tests with saltwater organisms Abs: 
1347165,Harden and  Johnson 2009,The Application of Soil Amendments to the Retardance of Rainwater-Leached Metals from CCA-Treated Wood Ash in Soil,,The Application of Soil Amendments to the Retardance of Rainwater-Leached Metals from CCA-Treated Wood Ash in Soil Abs: 
1346298,Fulladosa et al. 2006,Cr(VI) reduction into Cr(III) as a mechanism to explain the low sensitivity of Vibrio fischeri bioassay to detect chromium pollution,,Cr(VI) reduction into Cr(III) as a mechanism to explain the low sensitivity of Vibrio fischeri bioassay to detect chromium pollution Abs: 
1345242,Deliyanni et al. 2004,Metals removal from aqueous solution by iron-based bonding agents,"<strong>UNLABELLED: </strong>GOAL AND SCOPE AND BACKGROUND: The application of a promising method, termed sorptive flotation, for the removal of chromium(VI) and zinc ions was the aim of the present paper. A special case of sorptive flotation is adsorbing colloid flotation. Suitable sorbent preparation techniques have been developed in the laboratory.<br /><br /><strong>METHODS: </strong>Sorptive flotation, consisting of the sorption and flotation processes combined in series, has proved to give fast and satisfactory treatment of the industrial streams and effluents bearing dilute aqueous solutions of zinc and chromium(VI).<br /><br /><strong>RESULTS AND DISCUSSION: </strong>Goethite has proved to be effective for the removal of chromium(VI) and zinc ions. Also, adsorbing colloid flotation with ferric hydroxide (as the co-precipitant) could be an alternative method to the above-mentioned separation of metal ions. In both cases, chromium(VI) (pH=4) and zinc (pH=7) removal was about 100%.<br /><br /><strong>CONCLUSION: </strong>The reasons for selecting the iron-based bonding materials, like goethite and/or in-situ produced ferric hydroxide, are that they are cheap, easily synthesized, suitable both for cation and anion sorption, and, furthermore, that they present low risks for adding a further pollutant to the system. Promising results were obtained.<br /><br /><strong>RECOMMENDATION AND OUTLOOK: </strong>The application of goethite and in-situ produced ferric hydroxide has demonstrated their effectiveness in the removal of heavy metal ions, such as chromium anions and zinc cations. A proposed continuation of current work is the utilization of similar iron oxides, for instance synthesized akaganeite. The comparison between the results reported in this paper with the results reported in the literature, also deserves attention.","Metals removal from aqueous solution by iron-based bonding agents Abs: <strong>UNLABELLED: </strong>GOAL AND SCOPE AND BACKGROUND: The application of a promising method, termed sorptive flotation, for the removal of chromium(VI) and zinc ions was the aim of the present paper. A special case of sorptive flotation is adsorbing colloid flotation. Suitable sorbent preparation techniques have been developed in the laboratory.<br /><br /><strong>METHODS: </strong>Sorptive flotation, consisting of the sorption and flotation processes combined in series, has proved to give fast and satisfactory treatment of the industrial streams and effluents bearing dilute aqueous solutions of zinc and chromium(VI).<br /><br /><strong>RESULTS AND DISCUSSION: </strong>Goethite has proved to be effective for the removal of chromium(VI) and zinc ions. Also, adsorbing colloid flotation with ferric hydroxide (as the co-precipitant) could be an alternative method to the above-mentioned separation of metal ions. In both cases, chromium(VI) (pH=4) and zinc (pH=7) removal was about 100%.<br /><br /><strong>CONCLUSION: </strong>The reasons for selecting the iron-based bonding materials, like goethite and/or in-situ produced ferric hydroxide, are that they are cheap, easily synthesized, suitable both for cation and anion sorption, and, furthermore, that they present low risks for adding a further pollutant to the system. Promising results were obtained.<br /><br /><strong>RECOMMENDATION AND OUTLOOK: </strong>The application of goethite and in-situ produced ferric hydroxide has demonstrated their effectiveness in the removal of heavy metal ions, such as chromium anions and zinc cations. A proposed continuation of current work is the utilization of similar iron oxides, for instance synthesized akaganeite. The comparison between the results reported in this paper with the results reported in the literature, also deserves attention."
1343111,Baldwin and  Marshall 1999,Heavy metal poisoning and its laboratory investigation,BIOSIS COPYRIGHT: BIOL ABS. RRM LITERATURE REVIEW MERCURY THALLIUM LEAD BISMUTH THORIUM SERIES HEAVY METAL POISONING TOXICOLOGY TOXICITY MECHANISMS TOXICITY,Heavy metal poisoning and its laboratory investigation Abs: BIOSIS COPYRIGHT: BIOL ABS. RRM LITERATURE REVIEW MERCURY THALLIUM LEAD BISMUTH THORIUM SERIES HEAVY METAL POISONING TOXICOLOGY TOXICITY MECHANISMS TOXICITY
1342971,Ashraf et al. 2000,Heavy trace metal and macronutrient levels in various soft drinks and juices,,Heavy trace metal and macronutrient levels in various soft drinks and juices Abs: 
1339967,Kiani and  Mousavi 2013,Ultrasound assisted preparation of water in oil emulsions and their application in arsenic (V) removal from water in an emulsion liquid membrane process,"Water in oil emulsions are prepared by using an ultra-sonication device and used in an emulsion liquid membrane process in order to recover arsenic (V) ions from an aqueous medium. The aim of this work is the investigation of the effect of emulsifier concentration and composition, and also sonication time on the emulsion droplet size and the extraction efficiency in order to obtain stable emulsions with small droplets that favor the extraction. Results show that ultrasonic waves reduce internal droplet size which enhances the extraction of arsenic. In addition, internal droplet size is decreased initially and then increased by increasing Span 80 concentration. On the other hand, by increasing Span 80 concentration, extraction amount is increased and then decreased. Furthermore, emulsifier blends provide more stability for the emulsion. Increasing concentration of Tween 20 as a hydrophilic emulsifier up to an optimum concentration decreases internal droplet size and increases extraction amount. By increasing sonication time up to 4 min, the internal droplet size is decreased and the extraction amount is increased. If sonication time is increased further, the internal droplet size is increased and the extraction amount is decreased.","Ultrasound assisted preparation of water in oil emulsions and their application in arsenic (V) removal from water in an emulsion liquid membrane process Abs: Water in oil emulsions are prepared by using an ultra-sonication device and used in an emulsion liquid membrane process in order to recover arsenic (V) ions from an aqueous medium. The aim of this work is the investigation of the effect of emulsifier concentration and composition, and also sonication time on the emulsion droplet size and the extraction efficiency in order to obtain stable emulsions with small droplets that favor the extraction. Results show that ultrasonic waves reduce internal droplet size which enhances the extraction of arsenic. In addition, internal droplet size is decreased initially and then increased by increasing Span 80 concentration. On the other hand, by increasing Span 80 concentration, extraction amount is increased and then decreased. Furthermore, emulsifier blends provide more stability for the emulsion. Increasing concentration of Tween 20 as a hydrophilic emulsifier up to an optimum concentration decreases internal droplet size and increases extraction amount. By increasing sonication time up to 4 min, the internal droplet size is decreased and the extraction amount is increased. If sonication time is increased further, the internal droplet size is increased and the extraction amount is decreased."
1339829,Sheik et al. 2012,Exposure of soil microbial communities to chromium and arsenic alters their diversity and structure,"Extensive use of chromium (Cr) and arsenic (As) based preservatives from the leather tanning industry in Pakistan has had a deleterious effect on the soils surrounding production facilities. Bacteria have been shown to be an active component in the geochemical cycling of both Cr and As, but it is unknown how these compounds affect microbial community composition or the prevalence and form of metal resistance. Therefore, we sought to understand the effects that long-term exposure to As and Cr had on the diversity and structure of soil microbial communities. Soils from three spatially isolated tanning facilities in the Punjab province of Pakistan were analyzed. The structure, diversity and abundance of microbial 16S rRNA genes were highly influenced by the concentration and presence of hexavalent chromium (Cr (VI)) and arsenic. When compared to control soils, contaminated soils were dominated by Proteobacteria while Actinobacteria and Acidobacteria (which are generally abundant in pristine soils) were minor components of the bacterial community. Shifts in community composition were significant and revealed that Cr (VI)-containing soils were more similar to each other than to As contaminated soils lacking Cr (VI). Diversity of the arsenic resistance genes, arsB and ACR3 were also determined. Results showed that ACR3 becomes less diverse as arsenic concentrations increase with a single OTU dominating at the highest concentration. Chronic exposure to either Cr or As not only alters the composition of the soil bacterial community in general, but affects the arsenic resistant individuals in different ways.","Exposure of soil microbial communities to chromium and arsenic alters their diversity and structure Abs: Extensive use of chromium (Cr) and arsenic (As) based preservatives from the leather tanning industry in Pakistan has had a deleterious effect on the soils surrounding production facilities. Bacteria have been shown to be an active component in the geochemical cycling of both Cr and As, but it is unknown how these compounds affect microbial community composition or the prevalence and form of metal resistance. Therefore, we sought to understand the effects that long-term exposure to As and Cr had on the diversity and structure of soil microbial communities. Soils from three spatially isolated tanning facilities in the Punjab province of Pakistan were analyzed. The structure, diversity and abundance of microbial 16S rRNA genes were highly influenced by the concentration and presence of hexavalent chromium (Cr (VI)) and arsenic. When compared to control soils, contaminated soils were dominated by Proteobacteria while Actinobacteria and Acidobacteria (which are generally abundant in pristine soils) were minor components of the bacterial community. Shifts in community composition were significant and revealed that Cr (VI)-containing soils were more similar to each other than to As contaminated soils lacking Cr (VI). Diversity of the arsenic resistance genes, arsB and ACR3 were also determined. Results showed that ACR3 becomes less diverse as arsenic concentrations increase with a single OTU dominating at the highest concentration. Chronic exposure to either Cr or As not only alters the composition of the soil bacterial community in general, but affects the arsenic resistant individuals in different ways."
1338680,Seco-Reigosa et al. ,"Arsenic, chromium and mercury removal using mussel shell ash or a sludge/ashes waste mixture","Different batches of valued mussel shell and waste mussel shell ash are characterised. Shell ash has pH?&gt;?12 and high electrical conductivities (between 16.01 and 27.27 dS?m(-1)), while calcined shell shows pH values up to 10.7 and electrical conductivities between 1.19 and 3.55 dS?m(-1). X-ray fluorescence, nitric acid digestion and water extractions show higher concentrations in shell ash for most parameters. Calcite is the dominant crystalline compound in this ash (95.6 %), followed by aragonite. Adsorption/desorption trials were performed for mussel shell ash and for a waste mixture including shell ash, sewage sludge and wood ash, showing the following percentage adsorptions: Hg(II) &gt;94 %, As(V) &gt;96 % and Cr(VI) between 11 and 30 % for shell ash; Hg(II) &gt;98 %, As(V) &gt;88 % and Cr(VI) between 30 and 88 % for the waste mixture. Hg and As desorption was &lt;5 % for both shell ash and the waste mixture, while Cr desorption was between 92 and 45 % for shell ash, and between 19 and 0 % for the mixture. In view of that, mussel shell ash and the mixture including shell ash, sewage sludge and wood ash could be useful for Hg(II) and As(V) removal.","Arsenic, chromium and mercury removal using mussel shell ash or a sludge/ashes waste mixture Abs: Different batches of valued mussel shell and waste mussel shell ash are characterised. Shell ash has pH?&gt;?12 and high electrical conductivities (between 16.01 and 27.27 dS?m(-1)), while calcined shell shows pH values up to 10.7 and electrical conductivities between 1.19 and 3.55 dS?m(-1). X-ray fluorescence, nitric acid digestion and water extractions show higher concentrations in shell ash for most parameters. Calcite is the dominant crystalline compound in this ash (95.6 %), followed by aragonite. Adsorption/desorption trials were performed for mussel shell ash and for a waste mixture including shell ash, sewage sludge and wood ash, showing the following percentage adsorptions: Hg(II) &gt;94 %, As(V) &gt;96 % and Cr(VI) between 11 and 30 % for shell ash; Hg(II) &gt;98 %, As(V) &gt;88 % and Cr(VI) between 30 and 88 % for the waste mixture. Hg and As desorption was &lt;5 % for both shell ash and the waste mixture, while Cr desorption was between 92 and 45 % for shell ash, and between 19 and 0 % for the mixture. In view of that, mussel shell ash and the mixture including shell ash, sewage sludge and wood ash could be useful for Hg(II) and As(V) removal."
1338328,Nezamzadeh-Ejhieh and  Raja 2013,Modification of Nanoclinoptilolite Zeolite with Hexadecyltrimethylammonium Surfactant as an Active Ingredient of Chromate-Selective Membrane Electrode,,Modification of Nanoclinoptilolite Zeolite with Hexadecyltrimethylammonium Surfactant as an Active Ingredient of Chromate-Selective Membrane Electrode Abs: 
1337638,Giri et al. 2013,Biosorption of arsenic (III) from aqueous solution by living cells of Bacillus cereus,"In this work, removal of arsenic (III) from aqueous solution by living cells (Bacillus cereus), biosorption mechanism, and characterization studies have been reported. B. cereus cell surface was characterized using SEM-EDX and FTIR. Dependence of biosorption on pH of the solution, biosorbent dose, initial arsenic (III) concentration, contact time, and temperature had been studied to achieve optimum condition. The maximum biosorption capacity of living cells of B. cereus for arsenic (III) was found to be 32.42 mg/g at pH 7.5, at optimum conditions of contact time of 30 min, biomass dosage of 6 g/L, and temperature of 30?±?2 °C. Biosorption data of arsenic (III) are fitted to linearly transformed Langmuir isotherm with R (2) (correlation coefficient)?&gt;?0.99. The pseudo-second-order model description of the kinetics of arsenic (III) is successfully applied to predict the rate constant of biosorption. Thermodynamic parameters reveal the endothermic, spontaneous, and feasible nature of sorption process of arsenic (III) onto B. cereus biomass. The arsenic (III) ions are desorbed from B. cereus using both 1 M HCl and 1 M HNO(3).","Biosorption of arsenic (III) from aqueous solution by living cells of Bacillus cereus Abs: In this work, removal of arsenic (III) from aqueous solution by living cells (Bacillus cereus), biosorption mechanism, and characterization studies have been reported. B. cereus cell surface was characterized using SEM-EDX and FTIR. Dependence of biosorption on pH of the solution, biosorbent dose, initial arsenic (III) concentration, contact time, and temperature had been studied to achieve optimum condition. The maximum biosorption capacity of living cells of B. cereus for arsenic (III) was found to be 32.42 mg/g at pH 7.5, at optimum conditions of contact time of 30 min, biomass dosage of 6 g/L, and temperature of 30?±?2 °C. Biosorption data of arsenic (III) are fitted to linearly transformed Langmuir isotherm with R (2) (correlation coefficient)?&gt;?0.99. The pseudo-second-order model description of the kinetics of arsenic (III) is successfully applied to predict the rate constant of biosorption. Thermodynamic parameters reveal the endothermic, spontaneous, and feasible nature of sorption process of arsenic (III) onto B. cereus biomass. The arsenic (III) ions are desorbed from B. cereus using both 1 M HCl and 1 M HNO(3)."
1337354,Bachate et al. 2013,Simultaneous reduction of Cr(VI) and oxidation of As(III) by Bacillus firmus TE7 isolated from tannery effluent,"Hexavalent chromium [Cr(VI)] and arsenite [As(III)] are the most toxic forms of chromium and arsenic respectively, and reduction of Cr(VI) to Cr(III) and oxidation of As(III) to As(V) has great environmental implications as they affect toxicity and mobility of these toxic species. Bacillus firmus strain TE7, resistant to chromium and arsenic was isolated from tannery effluent. The strain exhibited ability to reduce Cr(VI) and oxidize As(III). It reduced 100mgL(-1) Cr(VI) within 60h in nutrient broth and oxidized 150mgL(-1) As(III) within 10h in minimal medium. It also completely reduced 15mgL(-1) Cr(VI) and oxidized 50mgL(-1) of As(III) simultaneously in minimal medium. To the best of our knowledge, this is the first bacterial strain showing simultaneous reduction of Cr(VI) and oxidation of As(III) and is a potential candidate for bioremediation of environments contaminated with these toxic metal species.","Simultaneous reduction of Cr(VI) and oxidation of As(III) by Bacillus firmus TE7 isolated from tannery effluent Abs: Hexavalent chromium [Cr(VI)] and arsenite [As(III)] are the most toxic forms of chromium and arsenic respectively, and reduction of Cr(VI) to Cr(III) and oxidation of As(III) to As(V) has great environmental implications as they affect toxicity and mobility of these toxic species. Bacillus firmus strain TE7, resistant to chromium and arsenic was isolated from tannery effluent. The strain exhibited ability to reduce Cr(VI) and oxidize As(III). It reduced 100mgL(-1) Cr(VI) within 60h in nutrient broth and oxidized 150mgL(-1) As(III) within 10h in minimal medium. It also completely reduced 15mgL(-1) Cr(VI) and oxidized 50mgL(-1) of As(III) simultaneously in minimal medium. To the best of our knowledge, this is the first bacterial strain showing simultaneous reduction of Cr(VI) and oxidation of As(III) and is a potential candidate for bioremediation of environments contaminated with these toxic metal species."
1337345,Hartwig 2013,Metal interaction with redox regulation: an integrating concept in metal carcinogenesis?,"The carcinogenicity of cadmium, arsenic, and chromium(VI) compounds has been recognized for some decades. However, the underlying molecular mechanisms seem to be complex and are not completely understood at present. Although, with the exception of chromium(VI), direct DNA damage seems to be of minor importance, interactions with DNA repair processes, tumor suppressor functions, and signal transduction pathways have been described in diverse biological systems. In addition to the induction of damage to cellular macromolecules by reactive oxygen species, the interference with cellular redox regulation by reaction with redox-sensitive protein domains or amino acids may provide one plausible mechanism involved in metal carcinogenicity. Consequences are the distortion of zinc-binding structures and the activation or inactivation of redox-regulated signal transduction pathways, provoking metal-induced genomic instability. Nevertheless, the relevance of the respective mechanisms depends on the actual metal or metal species under consideration and more research is needed to further strengthen this hypothesis.","Metal interaction with redox regulation: an integrating concept in metal carcinogenesis? Abs: The carcinogenicity of cadmium, arsenic, and chromium(VI) compounds has been recognized for some decades. However, the underlying molecular mechanisms seem to be complex and are not completely understood at present. Although, with the exception of chromium(VI), direct DNA damage seems to be of minor importance, interactions with DNA repair processes, tumor suppressor functions, and signal transduction pathways have been described in diverse biological systems. In addition to the induction of damage to cellular macromolecules by reactive oxygen species, the interference with cellular redox regulation by reaction with redox-sensitive protein domains or amino acids may provide one plausible mechanism involved in metal carcinogenicity. Consequences are the distortion of zinc-binding structures and the activation or inactivation of redox-regulated signal transduction pathways, provoking metal-induced genomic instability. Nevertheless, the relevance of the respective mechanisms depends on the actual metal or metal species under consideration and more research is needed to further strengthen this hypothesis."
1336167,Spaan et al. 2010,Variability of biomarkers in volunteer studies: The biological component,,Variability of biomarkers in volunteer studies: The biological component Abs: 
1335391,Tabershaw Occupational Medicine Associates 1982,"Occupational health evaluations of the Irving, Texas plant of Koppers Co., INC",,"Occupational health evaluations of the Irving, Texas plant of Koppers Co., INC Abs: "
1335087,Sedman and  Esparza 1991,EVALUATION OF THE PUBLIC HEALTH RISKS ASSOCIATED WITH SEMIVOLATILE METAL AND DIOXIN EMISSIONS FROM HAZARDOUS WASTE INCINERATORS,BIOSIS COPYRIGHT: BIOL ABS. RRM HUMAN CADMIUM CHROMIUM POLYCHLORINATED DIBENZODIOXIN POLYCHLORINATED DIBENZOFURAN,EVALUATION OF THE PUBLIC HEALTH RISKS ASSOCIATED WITH SEMIVOLATILE METAL AND DIOXIN EMISSIONS FROM HAZARDOUS WASTE INCINERATORS Abs: BIOSIS COPYRIGHT: BIOL ABS. RRM HUMAN CADMIUM CHROMIUM POLYCHLORINATED DIBENZODIOXIN POLYCHLORINATED DIBENZOFURAN
1334882,Wang 1990,LITERATURE REVIEW ON DUCKWEED TOXICITY TESTING,BIOSIS COPYRIGHT: BIOL ABS. RRM REVIEW LEMNA-MINOR LEMNA-GIBBA EFFLUENT BIOASSAY HERBICIDE POLLUTION TESTING LAKE RIVER WATER POLLUTION,LITERATURE REVIEW ON DUCKWEED TOXICITY TESTING Abs: BIOSIS COPYRIGHT: BIOL ABS. RRM REVIEW LEMNA-MINOR LEMNA-GIBBA EFFLUENT BIOASSAY HERBICIDE POLLUTION TESTING LAKE RIVER WATER POLLUTION
1332341,Walsh and  O'halloran 1997,"The Accumulation of chromium by mussels Mytilus edulis (L.) as a function of valency, solubility and ligation",,"The Accumulation of chromium by mussels Mytilus edulis (L.) as a function of valency, solubility and ligation Abs: "
1332196,Clarkson 1993,Molecular and Ionic Mimicry of Toxic Metals,"A review on oxyanion and divalent metal competition resulting in what has recently been termed molecular mimicry was presented. Molecular mimicry was defined as the binding of a metal cation and a cellular ligand, resulting in a structure so closely mirroring an endogenous substrate that it is then incorporated and used by the cellular metabolic machinery. Such occurrences have been reported for substances such as methylmercury-cysteine which has been found to mimic methionine and to be transported through the blood/brain barrier by an amino acid carrier and taken up by astrocytes, kidney cells, and other tissues, and methyl and inorganic mercury-glutathione complexes which have been reported to mimic conjugates of glutathione and oxidized glutathione resulting in the transport of such complexes out of liver cells and into the bile as well as out of other cells such as kidney and PC-12 cells in-vitro. Another example of molecular mimicry was discussed, involving methylmercury-cysteinylglycine mimicking acylglycines. The possibility of oxyanions of several toxic metals mimicking endogenous anions due to similarities in structure to phosphate, sulfate, and bicarbonate and chloride was discussed. In addition, the importance of ionic mimicry, whereby toxic metals mimic or take the place of essential metals, in the transport and toxicity of such metals at the cellular level was discussed.","Molecular and Ionic Mimicry of Toxic Metals Abs: A review on oxyanion and divalent metal competition resulting in what has recently been termed molecular mimicry was presented. Molecular mimicry was defined as the binding of a metal cation and a cellular ligand, resulting in a structure so closely mirroring an endogenous substrate that it is then incorporated and used by the cellular metabolic machinery. Such occurrences have been reported for substances such as methylmercury-cysteine which has been found to mimic methionine and to be transported through the blood/brain barrier by an amino acid carrier and taken up by astrocytes, kidney cells, and other tissues, and methyl and inorganic mercury-glutathione complexes which have been reported to mimic conjugates of glutathione and oxidized glutathione resulting in the transport of such complexes out of liver cells and into the bile as well as out of other cells such as kidney and PC-12 cells in-vitro. Another example of molecular mimicry was discussed, involving methylmercury-cysteinylglycine mimicking acylglycines. The possibility of oxyanions of several toxic metals mimicking endogenous anions due to similarities in structure to phosphate, sulfate, and bicarbonate and chloride was discussed. In addition, the importance of ionic mimicry, whereby toxic metals mimic or take the place of essential metals, in the transport and toxicity of such metals at the cellular level was discussed."
1332129,Bianchi and  Levis 1988,Review of genetic effects and mechanisms of action of chromium compounds,,Review of genetic effects and mechanisms of action of chromium compounds Abs: 
1332117,Bianchi and  Levis 1987,Recent advances in chromium genotoxicity,"More than 350 short?term genotoxicity tests have been performed up to date with Cr compounds, the more recent of which deal with the following aspects: (1) New tests have been developed to evaluate the mutagenicity of Cr, by the introduction of cell strains particularly sensitive to Cr(VI) mutagenicity, and the determination of particular conditions allowing to detect the genetic activity also of Cr(III). (2) Interactions of Cr(VI) and Cr(III) with purified nitrogen bases, polynucleotides, DNA, chromatin, nuclei and whole cells, have led to the identification of specific Cr(III)?DNA adducts, structural alterations of the genetic material, and effects on the DNA?repair functions, which can vary in different cell types and tissues. (3) The metabolism of Cr(VI) in mitochondrial, microsomal and soluble cell fractions has been related to inactivation mechanisms, some of which are inducible by Cr(VI) itself. Specific cell components able to reduce Cr(VI) to Cr(III), possibly via genetically active intermediate oxidation forms, have been identified. (4) Cytotoxic effects of Cr(VI) and Cr(III) have been detected in different cell systems, and some of them, such as the interferences with cell proliferation kinetics and DNA replication cycle, the effects on nucleic acid synthesis, and the embryotoxic effects, may be related to genotoxic mechanisms. (5) Interactions of Cr(VI) with other genotoxic agents have been pointed out, those with some environmentally relevant contaminants (such as nitrilotriacetic acid) being of particular interest. The already proposed mechanisms of Cr genotoxicity and the correlations between the mutagenic and carcinogenic activity of Cr are reviewed on the basis of the present data.","Recent advances in chromium genotoxicity Abs: More than 350 short?term genotoxicity tests have been performed up to date with Cr compounds, the more recent of which deal with the following aspects: (1) New tests have been developed to evaluate the mutagenicity of Cr, by the introduction of cell strains particularly sensitive to Cr(VI) mutagenicity, and the determination of particular conditions allowing to detect the genetic activity also of Cr(III). (2) Interactions of Cr(VI) and Cr(III) with purified nitrogen bases, polynucleotides, DNA, chromatin, nuclei and whole cells, have led to the identification of specific Cr(III)?DNA adducts, structural alterations of the genetic material, and effects on the DNA?repair functions, which can vary in different cell types and tissues. (3) The metabolism of Cr(VI) in mitochondrial, microsomal and soluble cell fractions has been related to inactivation mechanisms, some of which are inducible by Cr(VI) itself. Specific cell components able to reduce Cr(VI) to Cr(III), possibly via genetically active intermediate oxidation forms, have been identified. (4) Cytotoxic effects of Cr(VI) and Cr(III) have been detected in different cell systems, and some of them, such as the interferences with cell proliferation kinetics and DNA replication cycle, the effects on nucleic acid synthesis, and the embryotoxic effects, may be related to genotoxic mechanisms. (5) Interactions of Cr(VI) with other genotoxic agents have been pointed out, those with some environmentally relevant contaminants (such as nitrilotriacetic acid) being of particular interest. The already proposed mechanisms of Cr genotoxicity and the correlations between the mutagenic and carcinogenic activity of Cr are reviewed on the basis of the present data."
1328771,Wei et al. 2004,Chromium inhibits transcription from polycyclic aromatic hydrocarbon-inducible promoters by blocking the release of histone deacetylase and preventing the binding of p300 to chromatin,"Co-contamination with complex mixtures of carcinogenic metals, such as chromium, and polycyclic aromatic hydrocarbons is a common environmental problem with multiple biological consequences. Chromium exposure alters inducible gene expression, forms chromium-DNA adducts and chromium-DNA cross-links, and disrupts transcriptional activator-co-activator complexes. We have shown previously that exposure of mouse hepatoma Hepa-1 cells to chromate inhibits the induction of the Cyp1a1 and Nqo1 genes by dioxin. Here we have tested the hypothesis that chromium blocks gene expression by interfering with the assembly of productive transcriptional complexes at the promoter of inducible genes. To this end, we have studied the effects of chromium on the expression of genes induced by benzo[a]pyrene (B[a]P), another aryl hydrocarbon receptor agonist, and characterized the disruption of Cyp1a1 transcriptional induction by chromium. Gene expression profiling by using high density microarray analysis revealed that the inhibitory effect of chromium on B[a]P-dependent gene induction was generalized, affecting the induction of over 50 different genes involved in a variety of signaling transduction pathways. The inhibitory effect of chromium on Cyp1a1 transcription was found to depend on the presence of promoter-proximal sequences and not on the cis-acting enhancer sequences that bind the aryl hydrocarbon receptor-aryl hydrocarbon receptor nuclear translocator complex. By using transient reporter assays and chromatin immunoprecipitation analyses, we found that chromium prevented the B[a]P-dependent release of HDAC-1 from Cyp1a1 chromatin and blocked p300 recruitment. These results provide a mechanistic explanation for the observation that chromium inhibits inducible but not constitutive gene expression.","Chromium inhibits transcription from polycyclic aromatic hydrocarbon-inducible promoters by blocking the release of histone deacetylase and preventing the binding of p300 to chromatin Abs: Co-contamination with complex mixtures of carcinogenic metals, such as chromium, and polycyclic aromatic hydrocarbons is a common environmental problem with multiple biological consequences. Chromium exposure alters inducible gene expression, forms chromium-DNA adducts and chromium-DNA cross-links, and disrupts transcriptional activator-co-activator complexes. We have shown previously that exposure of mouse hepatoma Hepa-1 cells to chromate inhibits the induction of the Cyp1a1 and Nqo1 genes by dioxin. Here we have tested the hypothesis that chromium blocks gene expression by interfering with the assembly of productive transcriptional complexes at the promoter of inducible genes. To this end, we have studied the effects of chromium on the expression of genes induced by benzo[a]pyrene (B[a]P), another aryl hydrocarbon receptor agonist, and characterized the disruption of Cyp1a1 transcriptional induction by chromium. Gene expression profiling by using high density microarray analysis revealed that the inhibitory effect of chromium on B[a]P-dependent gene induction was generalized, affecting the induction of over 50 different genes involved in a variety of signaling transduction pathways. The inhibitory effect of chromium on Cyp1a1 transcription was found to depend on the presence of promoter-proximal sequences and not on the cis-acting enhancer sequences that bind the aryl hydrocarbon receptor-aryl hydrocarbon receptor nuclear translocator complex. By using transient reporter assays and chromatin immunoprecipitation analyses, we found that chromium prevented the B[a]P-dependent release of HDAC-1 from Cyp1a1 chromatin and blocked p300 recruitment. These results provide a mechanistic explanation for the observation that chromium inhibits inducible but not constitutive gene expression."
1327325,Schnekenburger et al. 2007,"Chromium cross-links histone deacetylase 1-DNA methyltransferase 1 complexes to chromatin, inhibiting histone-remodeling marks critical for transcriptional activation","Transcriptional regulation of gene expression requires posttranslational modification of histone proteins, which, in concert with chromatin-remodeling factors, modulate chromatin structure. Exposure to environmental agents may interfere with specific histone modifications and derail normal patterns of gene expression. To test this hypothesis, we coexposed cells to binary mixtures of benzo[a]pyrene (B[a]P), an environmental procarcinogen that activates Cyp1a1 transcriptional responses mediated by the aryl hydrocarbon receptor (AHR), and chromium, a carcinogenic heavy metal that represses B[a]P-inducible AHR-mediated gene expression. We show that chromium cross-links histone deacetylase 1-DNA methyltransferase 1 (HDAC1-DNMT1) complexes to Cyp1a1 promoter chromatin and inhibits histone marks induced by AHR-mediated gene transactivation, including phosphorylation of histone H3 Ser-10, trimethylation of H3 Lys-4, and various acetylation marks in histones H3 and H4. These changes inhibit RNA polymerase II recruitment without affecting the kinetics of AHR DNA binding. HDAC1 and DNMT1 inhibitors or depletion of HDAC1 or DNMT1 with siRNAs blocks chromium-induced transcriptional repression by decreasing the interaction of these proteins with the Cyp1a1 promoter and allowing histone acetylation to proceed. By inhibiting Cyp1a1 expression, chromium stimulates the formation of B[a]P DNA adducts. Epigenetic modification of gene expression patterns may be a key element of the developmental and carcinogenic outcomes of exposure to chromium and to other environmental agents.","Chromium cross-links histone deacetylase 1-DNA methyltransferase 1 complexes to chromatin, inhibiting histone-remodeling marks critical for transcriptional activation Abs: Transcriptional regulation of gene expression requires posttranslational modification of histone proteins, which, in concert with chromatin-remodeling factors, modulate chromatin structure. Exposure to environmental agents may interfere with specific histone modifications and derail normal patterns of gene expression. To test this hypothesis, we coexposed cells to binary mixtures of benzo[a]pyrene (B[a]P), an environmental procarcinogen that activates Cyp1a1 transcriptional responses mediated by the aryl hydrocarbon receptor (AHR), and chromium, a carcinogenic heavy metal that represses B[a]P-inducible AHR-mediated gene expression. We show that chromium cross-links histone deacetylase 1-DNA methyltransferase 1 (HDAC1-DNMT1) complexes to Cyp1a1 promoter chromatin and inhibits histone marks induced by AHR-mediated gene transactivation, including phosphorylation of histone H3 Ser-10, trimethylation of H3 Lys-4, and various acetylation marks in histones H3 and H4. These changes inhibit RNA polymerase II recruitment without affecting the kinetics of AHR DNA binding. HDAC1 and DNMT1 inhibitors or depletion of HDAC1 or DNMT1 with siRNAs blocks chromium-induced transcriptional repression by decreasing the interaction of these proteins with the Cyp1a1 promoter and allowing histone acetylation to proceed. By inhibiting Cyp1a1 expression, chromium stimulates the formation of B[a]P DNA adducts. Epigenetic modification of gene expression patterns may be a key element of the developmental and carcinogenic outcomes of exposure to chromium and to other environmental agents."
1327275,Glaviano et al. 2006,Effects of hTERT on metal ion-induced genomic instability,"There is currently a great interest in delayed chromosomal and other damaging effects of low-dose exposure to a variety of pollutants which appear collectively to act through induction of stress-response pathways related to oxidative stress and ageing. These have been studied mostly in the radiation field but evidence is accumulating that the mechanisms can also be triggered by chemicals, especially heavy metals. Humans are exposed to metals, including chromium (Cr) (VI) and vanadium (V) (V), from the environment, industry and surgical implants. Thus, the impact of low-dose stress responses may be larger than expected from individual toxicity projections. In this study, a short (24 h) exposure of human fibroblasts to low doses of Cr (VI) and V (V) caused both acute chromosome damage and genomic instability in the progeny of exposed cells for at least 30 days after exposure. Acutely, Cr (VI) caused chromatid breaks without aneuploidy while V (V) caused aneuploidy without chromatid breaks. The longer-term genomic instability was similar but depended on hTERT positivity. In telomerase-negative hTERT- cells, Cr (VI) and V (V) caused a long lasting and transmissible induction of dicentric chromosomes, nucleoplasmic bridges, micronuclei and aneuploidy. There was also a long term and transmissible reduction of clonogenic survival, with an increased beta-galactosidase staining and apoptosis. This instability was not present in telomerase-positive hTERT+ cells. In contrast, in hTERT+ cells the metals caused a persistent induction of tetraploidy, which was not noted in hTERT- cells. The growth and survival of both metal-exposed hTERT+ and hTERT- cells differed if they were cultured at subconfluent levels or plated out as colonies. Genomic instability is considered to be a driving force towards cancer. This study suggests that the type of genomic instability in human cells may depend critically on whether they are telomerase-positive or -negative and that their sensitivities to metals could depend on whether they are clustered or diffuse.","Effects of hTERT on metal ion-induced genomic instability Abs: There is currently a great interest in delayed chromosomal and other damaging effects of low-dose exposure to a variety of pollutants which appear collectively to act through induction of stress-response pathways related to oxidative stress and ageing. These have been studied mostly in the radiation field but evidence is accumulating that the mechanisms can also be triggered by chemicals, especially heavy metals. Humans are exposed to metals, including chromium (Cr) (VI) and vanadium (V) (V), from the environment, industry and surgical implants. Thus, the impact of low-dose stress responses may be larger than expected from individual toxicity projections. In this study, a short (24 h) exposure of human fibroblasts to low doses of Cr (VI) and V (V) caused both acute chromosome damage and genomic instability in the progeny of exposed cells for at least 30 days after exposure. Acutely, Cr (VI) caused chromatid breaks without aneuploidy while V (V) caused aneuploidy without chromatid breaks. The longer-term genomic instability was similar but depended on hTERT positivity. In telomerase-negative hTERT- cells, Cr (VI) and V (V) caused a long lasting and transmissible induction of dicentric chromosomes, nucleoplasmic bridges, micronuclei and aneuploidy. There was also a long term and transmissible reduction of clonogenic survival, with an increased beta-galactosidase staining and apoptosis. This instability was not present in telomerase-positive hTERT+ cells. In contrast, in hTERT+ cells the metals caused a persistent induction of tetraploidy, which was not noted in hTERT- cells. The growth and survival of both metal-exposed hTERT+ and hTERT- cells differed if they were cultured at subconfluent levels or plated out as colonies. Genomic instability is considered to be a driving force towards cancer. This study suggests that the type of genomic instability in human cells may depend critically on whether they are telomerase-positive or -negative and that their sensitivities to metals could depend on whether they are clustered or diffuse."
1321966,Koca et al. 2011,Patch Test Results in Patients with Allergic Contact Dermatitis in the Western Black Sea Region: A Five-Year Retrospective Study,,Patch Test Results in Patients with Allergic Contact Dermatitis in the Western Black Sea Region: A Five-Year Retrospective Study Abs: 
1321939,Kiec-Swierczynska et al. 2012,"Trends in allergy to the 10 most frequent contact allergens in patients examined at the Nofer Institute, Lodz, Poland in 1996-2009",,"Trends in allergy to the 10 most frequent contact allergens in patients examined at the Nofer Institute, Lodz, Poland in 1996-2009 Abs: "
1321833,Helmbold et al. 1994,INDUCTION OF TYPE-IV HYPERSENSITIVITY IN ANIMAL BY IN-VITRO HAPTENIZED PERITONEAL-EXUDATE CELLS,,INDUCTION OF TYPE-IV HYPERSENSITIVITY IN ANIMAL BY IN-VITRO HAPTENIZED PERITONEAL-EXUDATE CELLS Abs: 
1320866,Elrab and  Alsheikh 1995,"IS THE EUROPEAN STANDARD SERIES SUITABLE FOR PATCH TESTING IN RIYADB, SAUDI-ARABIA",,"IS THE EUROPEAN STANDARD SERIES SUITABLE FOR PATCH TESTING IN RIYADB, SAUDI-ARABIA Abs: "
1320295,Calka et al. 2011,The Results of Patch Testing in Patients with Contact Dermatitis in Eastern Turkey,,The Results of Patch Testing in Patients with Contact Dermatitis in Eastern Turkey Abs: 
1319804,Sancak et al. 2009,Application of patch test in allergic (atopic) dogs and investigation of dog allergy incidence in people,,Application of patch test in allergic (atopic) dogs and investigation of dog allergy incidence in people Abs: 
1319638,Uter et al. 2002,Reproducibility of patch testing - an analysis of concordance with synchronous application,,Reproducibility of patch testing - an analysis of concordance with synchronous application Abs: 
1317093,standards 1981,Scientific basis for Swedish Occupational Standards. Consensus report for formaldehyde,,Scientific basis for Swedish Occupational Standards. Consensus report for formaldehyde Abs: 
1316620,Mclaughlin 1994,Formaldehyde and cancer: A critical review,"BIOSIS COPYRIGHT: BIOL ABS. Formaldehyde is a naturally occurring chemical found in every human cell. It has been in widespread use for over a century as a disinfectant and preservative agent, and more recently in a number of industrial products. Animal studies indicate that formaldehyde is a rat carcinogen at high levels (| 10 ppm) of exposure. Results for lower levels of exposure show less clear-cut carcinogenic effects, and some species, such as mice and hamsters, appear much less sensitive to any carcinogenic potential of formaldehyde. Epidemiologic studies of the effects of formaldehyde exposure among humans provide inconsistent results. In general, these nonexperimental studies suffer from a number of biases and flaws. The epidemiologic studies fall into three categories formaldehyde industry workers, case-control studies, and studies of professionals who use formaldehyde. Studies of industry workers with known exposure to formaldehyde report little evidence of an excess cancer risk. Nasoph","Formaldehyde and cancer: A critical review Abs: BIOSIS COPYRIGHT: BIOL ABS. Formaldehyde is a naturally occurring chemical found in every human cell. It has been in widespread use for over a century as a disinfectant and preservative agent, and more recently in a number of industrial products. Animal studies indicate that formaldehyde is a rat carcinogen at high levels (| 10 ppm) of exposure. Results for lower levels of exposure show less clear-cut carcinogenic effects, and some species, such as mice and hamsters, appear much less sensitive to any carcinogenic potential of formaldehyde. Epidemiologic studies of the effects of formaldehyde exposure among humans provide inconsistent results. In general, these nonexperimental studies suffer from a number of biases and flaws. The epidemiologic studies fall into three categories formaldehyde industry workers, case-control studies, and studies of professionals who use formaldehyde. Studies of industry workers with known exposure to formaldehyde report little evidence of an excess cancer risk. Nasoph"
1315945,Osbild et al. 1995,Review - State of the Art: Biosensors for environmental monitoring and water control,"BIOSIS COPYRIGHT: BIOL ABS. This paper reviews the use of biosensors for environmental biomonitoring and especially for the detection of water pollutants. These systems are developed in view of on-line applications, continuous and real time analysis. The principle and the design of the different systems proposed for this purpose are described with their performances deduced from pilot or in situ studies carried out up to now. Automation and autonomy, sensitivity and specificity are critical points that will determine the success of their applications in biomonitoring and the kind of application that can be envisaged. It is necessary they require minimal human intervention for maintenance and working. The more sensitive systems can be used for the monitoring of drinking and ground waters, the less sensitive ones for the monitoring of complex effluents, more heavily contaminated. Biosensors can be distinguished on the basis of the type of biocatalyst associated with the transducer: the biological si","Review - State of the Art: Biosensors for environmental monitoring and water control Abs: BIOSIS COPYRIGHT: BIOL ABS. This paper reviews the use of biosensors for environmental biomonitoring and especially for the detection of water pollutants. These systems are developed in view of on-line applications, continuous and real time analysis. The principle and the design of the different systems proposed for this purpose are described with their performances deduced from pilot or in situ studies carried out up to now. Automation and autonomy, sensitivity and specificity are critical points that will determine the success of their applications in biomonitoring and the kind of application that can be envisaged. It is necessary they require minimal human intervention for maintenance and working. The more sensitive systems can be used for the monitoring of drinking and ground waters, the less sensitive ones for the monitoring of complex effluents, more heavily contaminated. Biosensors can be distinguished on the basis of the type of biocatalyst associated with the transducer: the biological si"
1314917,Hegyi 1979,[Development tendencies of the contact allergy],"The development tendencies of the contact allergy in the given catch-area in the years 1948-1977 are studied here by the help of a systematic examination of the dynamics concerning the hypersensitivity of the population. By means of patch tests applied to 15685 patients/6864 men and 8821 women/reactors are checked up towards 15 contact allergens/hexavalent and trivalent chromium, nickel, cobalt, procaine, paraphenylenediamine, neomycine, mercury bichloride, resorcinol, camomile, paraben mixture, formaldehyde, balsam of Peru, turpentine oil, rubber chemicals, and the connections between the percentage of the reactors and the alterations in the technology of the production as well as of the degree and effektiveness of the preventive measures and of the introduction of new remedies, cosmetics and necessaries for daily use are being determined. At the same time this study and the results achieved by analysis are the basis for preventive measures to be taken according to the characteristics of the contact allergens and in proportion to the possibility of taking such measures.","[Development tendencies of the contact allergy] Abs: The development tendencies of the contact allergy in the given catch-area in the years 1948-1977 are studied here by the help of a systematic examination of the dynamics concerning the hypersensitivity of the population. By means of patch tests applied to 15685 patients/6864 men and 8821 women/reactors are checked up towards 15 contact allergens/hexavalent and trivalent chromium, nickel, cobalt, procaine, paraphenylenediamine, neomycine, mercury bichloride, resorcinol, camomile, paraben mixture, formaldehyde, balsam of Peru, turpentine oil, rubber chemicals, and the connections between the percentage of the reactors and the alterations in the technology of the production as well as of the degree and effektiveness of the preventive measures and of the introduction of new remedies, cosmetics and necessaries for daily use are being determined. At the same time this study and the results achieved by analysis are the basis for preventive measures to be taken according to the characteristics of the contact allergens and in proportion to the possibility of taking such measures."
1312878,Roller 2011,In vitro genotoxicity data of nanomaterials compared to carcinogenic potency of inorganic substances after inhalational exposure,"Literature data of epidemiological studies, carcinogenicity studies and in vitro studies on inorganic substances were surveyed with the aim to determine sensitivity and specificity of in vitro tests of nanomaterials. Asbestos, quartz and chromium and cadmium compounds were assigned to classes of highest carcinogenic potency. After 20 years of occupational exposure to long-term average concentrations of 0.5mg/m(3) of these dusts - or to even lower concentrations - an epidemiologically detectable increased lung cancer risk has to be expected. In contrast, diesel engine emissions, some nickel species and &quot;ultrafine&quot; versions (nanomaterials) of titanium dioxide and carbon black were also carcinogenic in inhalation studies, but show varied epidemiological results. The high frequency of lung cancer in the male general population due to cigarette smoking hampers unequivocal detection of occupationally caused lung cancer risks. Based on the experience from the inhalation studies, workers had to be exposed to long-term concentrations of 1mg/m(3) or more to identify epidemiologically a clear cause-and-effect relationship for a specific substance of intermediate potency. Respirable granular biodurable particles without known significant specific toxicity with primary particle sizes of more than 1?m have also shown carcinogenicity in rats. Their potency was even lower; and partially results after instillation rather than inhalation are available. Nearly all types of nanomaterials and control dusts used in the in vitro assays showed genotoxic effects in cell cultures (e.g., CoCr particles, diesel soot, SiO(2) crystalline and amorphous, TiO(2), carbon black), but not consistently in all studies; overall, the proportion of positive results was about 50%. No clear correlation of the probability of a positive in vitro test with particle properties was seen. I recommend trying and calibrating a sensitive in vitro model (e.g., micronucleus assay) against the described rank order of carcinogenic potency by testing a series of inorganic substances.","In vitro genotoxicity data of nanomaterials compared to carcinogenic potency of inorganic substances after inhalational exposure Abs: Literature data of epidemiological studies, carcinogenicity studies and in vitro studies on inorganic substances were surveyed with the aim to determine sensitivity and specificity of in vitro tests of nanomaterials. Asbestos, quartz and chromium and cadmium compounds were assigned to classes of highest carcinogenic potency. After 20 years of occupational exposure to long-term average concentrations of 0.5mg/m(3) of these dusts - or to even lower concentrations - an epidemiologically detectable increased lung cancer risk has to be expected. In contrast, diesel engine emissions, some nickel species and &quot;ultrafine&quot; versions (nanomaterials) of titanium dioxide and carbon black were also carcinogenic in inhalation studies, but show varied epidemiological results. The high frequency of lung cancer in the male general population due to cigarette smoking hampers unequivocal detection of occupationally caused lung cancer risks. Based on the experience from the inhalation studies, workers had to be exposed to long-term concentrations of 1mg/m(3) or more to identify epidemiologically a clear cause-and-effect relationship for a specific substance of intermediate potency. Respirable granular biodurable particles without known significant specific toxicity with primary particle sizes of more than 1?m have also shown carcinogenicity in rats. Their potency was even lower; and partially results after instillation rather than inhalation are available. Nearly all types of nanomaterials and control dusts used in the in vitro assays showed genotoxic effects in cell cultures (e.g., CoCr particles, diesel soot, SiO(2) crystalline and amorphous, TiO(2), carbon black), but not consistently in all studies; overall, the proportion of positive results was about 50%. No clear correlation of the probability of a positive in vitro test with particle properties was seen. I recommend trying and calibrating a sensitive in vitro model (e.g., micronucleus assay) against the described rank order of carcinogenic potency by testing a series of inorganic substances."
1297915,Perez-Benito 2006,Effects of chromium(VI) and vanadium(V) on the lifespan of fish,"The effect of chromium(VI) on the lifespan of laboratory-reared guppies (Poecilia reticulata) has been studied both in the absence and in the presence of the antioxidant D-mannitol, and it has been compared with that produced by vanadium(V). The three substances used as additives exhibited either a weak (D-mannitol), a moderate (chromate) or an acute (vanadate) toxicity to fish. Vanadate, with LC50 (7 days) = 3.84 x 10(-5) mol/L, was about ten times more toxic than chromate, with LC50 (7 days) = 3.42 x 10(-4) mol/L as a single additive and 4.27 x 10(-4) mol/L in the presence of d-mannitol. An increasing effect on the maximum lifespan of males was observed when the additives studied were used at low concentrations, either alone or in a binary combination, following the sequence: vanadate (14%) &lt; D-mannitol (41%) &lt; chromate + D-mannitol (57%) &lt; chromate (69%). Of these substances, only chromate increased also the maximum lifespan of females (72%). The maximum lifespan showed a strong, positive correlation with the concentration of chromate for males (P = 0.00008) and a weaker, positive correlation (P = 0.116) for females. These results suggest the existence of a chemical-hormesis phenomenon that might be subjected to sexual-genre variability. Both the toxicity and the chemical-hormetic effect provoked by chromate were substantially decreased when it was used in combination with d-mannitol, and the possible causes for this double inhibition are briefly discussed.","Effects of chromium(VI) and vanadium(V) on the lifespan of fish Abs: The effect of chromium(VI) on the lifespan of laboratory-reared guppies (Poecilia reticulata) has been studied both in the absence and in the presence of the antioxidant D-mannitol, and it has been compared with that produced by vanadium(V). The three substances used as additives exhibited either a weak (D-mannitol), a moderate (chromate) or an acute (vanadate) toxicity to fish. Vanadate, with LC50 (7 days) = 3.84 x 10(-5) mol/L, was about ten times more toxic than chromate, with LC50 (7 days) = 3.42 x 10(-4) mol/L as a single additive and 4.27 x 10(-4) mol/L in the presence of d-mannitol. An increasing effect on the maximum lifespan of males was observed when the additives studied were used at low concentrations, either alone or in a binary combination, following the sequence: vanadate (14%) &lt; D-mannitol (41%) &lt; chromate + D-mannitol (57%) &lt; chromate (69%). Of these substances, only chromate increased also the maximum lifespan of females (72%). The maximum lifespan showed a strong, positive correlation with the concentration of chromate for males (P = 0.00008) and a weaker, positive correlation (P = 0.116) for females. These results suggest the existence of a chemical-hormesis phenomenon that might be subjected to sexual-genre variability. Both the toxicity and the chemical-hormetic effect provoked by chromate were substantially decreased when it was used in combination with d-mannitol, and the possible causes for this double inhibition are briefly discussed."
1297806,Lee and  Choi 2007,"Effects of bisphenol A and ethynyl estradiol exposure on enzyme activities, growth and development in the fourth instar larvae of Chironomus riparius (Diptera, Chironomidae)","This study was conducted to determine the toxic effects of bisphenol A (BPA) and ethynyl estradiol (EE), well-known endocrine disruptors, on Chironomus riparius under controlled laboratory conditions. Mortality, enzyme activities, and growth/development parameters were studied as acute, biochemical, and physiological toxicities, respectively. The results of the present study showed activation of catalase and glutathione-S-transferase after BPA and EE exposure, as well as increased emergence failure after EE exposure. This study on the effects of BPA and EE on C. riparius can be an important addition to the knowledge that has been obtained regarding the toxicology of BPA and EE in aquatic organism, on which limited data are available. The data obtained from this study, however, are not sufficient to establish any correlation or casual relationship between these two compounds and the response of C. riparius. Thus, further research is required to come up with direct experimental demonstrations of the wider relationship between the biochemical effects of BPA and EE on C. riparius and their consequences at higher levels of biological organization.","Effects of bisphenol A and ethynyl estradiol exposure on enzyme activities, growth and development in the fourth instar larvae of Chironomus riparius (Diptera, Chironomidae) Abs: This study was conducted to determine the toxic effects of bisphenol A (BPA) and ethynyl estradiol (EE), well-known endocrine disruptors, on Chironomus riparius under controlled laboratory conditions. Mortality, enzyme activities, and growth/development parameters were studied as acute, biochemical, and physiological toxicities, respectively. The results of the present study showed activation of catalase and glutathione-S-transferase after BPA and EE exposure, as well as increased emergence failure after EE exposure. This study on the effects of BPA and EE on C. riparius can be an important addition to the knowledge that has been obtained regarding the toxicology of BPA and EE in aquatic organism, on which limited data are available. The data obtained from this study, however, are not sufficient to establish any correlation or casual relationship between these two compounds and the response of C. riparius. Thus, further research is required to come up with direct experimental demonstrations of the wider relationship between the biochemical effects of BPA and EE on C. riparius and their consequences at higher levels of biological organization."
1291273,Maksin et al. 2012,Equilibrium and kinetics study on hexavalent chromium adsorption onto diethylene triamine grafted glycidyl methacrylate based copolymers,"Two porous and one non-porous crosslinked poly(glycidyl methacrylate-co-ethylene glycol dimethacrylate) [abbreviated PGME] were prepared by suspension copolymerization and functionalized with diethylene triamine [abbreviated PGME-deta]. Samples were characterized by elemental analysis, mercury porosimetry, scanning electron microscopy with energy-dispersive X-ray spectroscopy, and transmission electron microscopy. Kinetics of Cr(VI) sorption by PGME-deta were investigated in batch static experiments, in the temperature range 25-70°C. Sorption was rapid, with the uptake capacity higher than 80% after 30 min. Sorption behavior and rate-controlling mechanisms were analyzed using five kinetic models (pseudo-first order, pseudo-second order, Elovich, intraparticle diffusion and Bangham model). Kinetic studies showed that Cr(VI) adsorption adhered to the pseudo-second-order model, with definite influence of pore diffusion. Equilibrium data was tested with Langmuir, Freundlich and Tempkin adsorption isotherm models. Langmuir model was the most suitable indicating homogeneous distribution of active sites on PGME-deta and monolayer sorption. The maximum adsorption capacity from the Langmuir model, Q(max), at pH 1.8 and 25°C was 143 mg g(-1) for PGME2-deta (sample with the highest amino group concentration) while at 70°C Q(max) reached the high value of 198 mg g(-1). Thermodynamic parameters revealed spontaneous and endothermic nature of Cr(VI) adsorption onto PGME-deta.","Equilibrium and kinetics study on hexavalent chromium adsorption onto diethylene triamine grafted glycidyl methacrylate based copolymers Abs: Two porous and one non-porous crosslinked poly(glycidyl methacrylate-co-ethylene glycol dimethacrylate) [abbreviated PGME] were prepared by suspension copolymerization and functionalized with diethylene triamine [abbreviated PGME-deta]. Samples were characterized by elemental analysis, mercury porosimetry, scanning electron microscopy with energy-dispersive X-ray spectroscopy, and transmission electron microscopy. Kinetics of Cr(VI) sorption by PGME-deta were investigated in batch static experiments, in the temperature range 25-70°C. Sorption was rapid, with the uptake capacity higher than 80% after 30 min. Sorption behavior and rate-controlling mechanisms were analyzed using five kinetic models (pseudo-first order, pseudo-second order, Elovich, intraparticle diffusion and Bangham model). Kinetic studies showed that Cr(VI) adsorption adhered to the pseudo-second-order model, with definite influence of pore diffusion. Equilibrium data was tested with Langmuir, Freundlich and Tempkin adsorption isotherm models. Langmuir model was the most suitable indicating homogeneous distribution of active sites on PGME-deta and monolayer sorption. The maximum adsorption capacity from the Langmuir model, Q(max), at pH 1.8 and 25°C was 143 mg g(-1) for PGME2-deta (sample with the highest amino group concentration) while at 70°C Q(max) reached the high value of 198 mg g(-1). Thermodynamic parameters revealed spontaneous and endothermic nature of Cr(VI) adsorption onto PGME-deta."
1290456,Barchowsky 2006,JNK activation by chromium in the lung,"Inhaled hexavalent chromium (Cr(VI)) promotes pulmonary diseases through poorly defined mechanisms that may involve both direct metal interactions with proteins and indirect signaling through generation of reactive oxygen species (ROS). Human lung epithelial cells were exposed to non-cytotoxic concentrations of Cr(VI) to investigate the hypothesis that Cr(VI) selectively activates cell signaling to both induce and silence genes. These studies demonstrated that non-toxic doses of Cr(VI) stimulated the Src family kinases (SFK) Lck and Fyn, but not Src or Yes. Stimulation of SFKs led to selective activation of JNK, relative to ERK or p38 MAP kinase. While Cr(VI) slightly elevated ROS levels, much higher non-selective and toxic levels of exogenous ROS were needed to stimulate SFKs and JNK. Thiol oxidation and the adaptor protein p130cas (Cas) were common requirements for Cr(VI) and H2O2 to activate JNK. However, Cr(VI) and H2O2 had differential effects on the SFKs that may account for divergence of the metal and ROS signaling pathways. Finally, Cr(VI), but not H2O2, directly activated purified Fyn in vitro, which confirmed the selective action of the metal. These data indicate that Cr(VI), at levels which are relevant to human exposures, selectively stimulates cell signaling to regulate gene induction and silencing. This selective action of Cr(VI) does not always require ROS signaling in airway epithelial cells, which suggests a possible mechanism that distinguishes Cr(VI)-induced diseases from general inflammatory diseases.","JNK activation by chromium in the lung Abs: Inhaled hexavalent chromium (Cr(VI)) promotes pulmonary diseases through poorly defined mechanisms that may involve both direct metal interactions with proteins and indirect signaling through generation of reactive oxygen species (ROS). Human lung epithelial cells were exposed to non-cytotoxic concentrations of Cr(VI) to investigate the hypothesis that Cr(VI) selectively activates cell signaling to both induce and silence genes. These studies demonstrated that non-toxic doses of Cr(VI) stimulated the Src family kinases (SFK) Lck and Fyn, but not Src or Yes. Stimulation of SFKs led to selective activation of JNK, relative to ERK or p38 MAP kinase. While Cr(VI) slightly elevated ROS levels, much higher non-selective and toxic levels of exogenous ROS were needed to stimulate SFKs and JNK. Thiol oxidation and the adaptor protein p130cas (Cas) were common requirements for Cr(VI) and H2O2 to activate JNK. However, Cr(VI) and H2O2 had differential effects on the SFKs that may account for divergence of the metal and ROS signaling pathways. Finally, Cr(VI), but not H2O2, directly activated purified Fyn in vitro, which confirmed the selective action of the metal. These data indicate that Cr(VI), at levels which are relevant to human exposures, selectively stimulates cell signaling to regulate gene induction and silencing. This selective action of Cr(VI) does not always require ROS signaling in airway epithelial cells, which suggests a possible mechanism that distinguishes Cr(VI)-induced diseases from general inflammatory diseases."
1290455,Zhitkovich et al. 2006,Abnormal processing of chromium-DNA adducts by mismatch repair proteins activates genotoxicity of chromium(VI),"Hexavalent chromium (CrVI) is toxic and carcinogenic metal with widespread human exposure. Intracellular reduction of Cr(VI) leads to the formation of numerous Cr-DNA adducts that are genotoxic during replication in human cells but not in vitro. We have found that several human and mouse cell lines lacking different mismatch repair (MMR) proteins had much higher clonogenic survival compared to MMR-proficient cells. Normal cells underwent massive apoptosis following Cr(VI) treatment, whereas Cr-treated MMR-deficient cells induced minimal apoptosis. MMR-activated apoptosis in Cr-treated cells did not involve p53 transcriptional factor because stable knockdown of p53 with short hairpin (sh)RNA had no significant effect on clonogenic survival or apoptosis following Cr(VI) exposure. Additionally, we found only minimal changes in p53 protein levels, serine- 15 phosphorylation and no p53 reporter activation. Several hours prior to the appearance of the earliest markers of apoptosis, Cr(VI)-treated MMR-proficient cells accumulated high levels of DNA double-strand breaks that were detected by the presence of gamma-H2AX foci and by pulse-field gel electrophoresis. The majority of the gamma-H2AX foci ( > =80%) localized to G2 phase of the cell cycle in the absence of any G2 arrest. Pull-down experiments with Cr-modified DNA templates identified MSH2-MSH6 heterodimer as the key MMR complex responsible for the recognition of Cr-DNA adducts. Overall, our data indicate that MMR proteins act as sensors of Cr-DNA damage and activate cell death though the induction of double- strand breaks as secondary toxic lesions.","Abnormal processing of chromium-DNA adducts by mismatch repair proteins activates genotoxicity of chromium(VI) Abs: Hexavalent chromium (CrVI) is toxic and carcinogenic metal with widespread human exposure. Intracellular reduction of Cr(VI) leads to the formation of numerous Cr-DNA adducts that are genotoxic during replication in human cells but not in vitro. We have found that several human and mouse cell lines lacking different mismatch repair (MMR) proteins had much higher clonogenic survival compared to MMR-proficient cells. Normal cells underwent massive apoptosis following Cr(VI) treatment, whereas Cr-treated MMR-deficient cells induced minimal apoptosis. MMR-activated apoptosis in Cr-treated cells did not involve p53 transcriptional factor because stable knockdown of p53 with short hairpin (sh)RNA had no significant effect on clonogenic survival or apoptosis following Cr(VI) exposure. Additionally, we found only minimal changes in p53 protein levels, serine- 15 phosphorylation and no p53 reporter activation. Several hours prior to the appearance of the earliest markers of apoptosis, Cr(VI)-treated MMR-proficient cells accumulated high levels of DNA double-strand breaks that were detected by the presence of gamma-H2AX foci and by pulse-field gel electrophoresis. The majority of the gamma-H2AX foci ( > =80%) localized to G2 phase of the cell cycle in the absence of any G2 arrest. Pull-down experiments with Cr-modified DNA templates identified MSH2-MSH6 heterodimer as the key MMR complex responsible for the recognition of Cr-DNA adducts. Overall, our data indicate that MMR proteins act as sensors of Cr-DNA damage and activate cell death though the induction of double- strand breaks as secondary toxic lesions."
1290454,O’Brien et al. 2005,Impairment of chromium-DNA adduct formation by hypoxia,"The reduction of hexavalent chromium [Cr(VI)] generates several genetic lesions. While mechanisms include both direct metal-DNA interactions and the generation of radical intermediates, the precise role of oxygen in this process is unclear. We studied the formation of Cr-induced lesions in DNA in vitro reacted with either Cr(VI) and ascorbic acid (Asc), or Cr(III), under both ambient and hypoxic conditions. Hypoxia had no effect on the kinetics of Cr(VI) reduction by Asc, but decreased, by ~50%, the levels of Cr(VI)/Asc-induced Cr-DNA adducts and DNA polymerase-arresting lesions (PALs) following a 2 hour treatment. In addition, hypoxia impaired the formation of Cr-induced DNA interstrand crosslinks by ~2-fold in plasmid DNA treated with Cr(VI)/Asc. Although the effects of oxygen deprivation were pronounced after 2 hours; following a 20 hour incubation of DNA with Cr(VI)/Asc, Cr-DNA adduct levels were again similar under both ambient and hypoxic conditions indicating that hypoxia reduced the rate at which Cr interacted with DNA, but not the ultimate steady state level of Cr-DNA binding. The inhibitory effect of hypoxia on Cr(VI)/Asc genotoxicity could not be explained by alterations in the reactivity of intermediate Cr species [i.e. Cr(V)] because Cr(III)-induced DNA damage (adducts, PALs, ICLs) was also impaired by hypoxia. Moreover, the production of Cr(V), as detected by electron spin resonance (ESR), was similar in ambient and hypoxic reactions. These effects were specific for Cr(III) because hypoxia did not affect the generation of ICLs by cisplatin, another inorganic DNA crosslinking agent. Taken together, the results from this study reveal a novel oxygen-dependent step in Cr genotoxicity wherein molecular oxygen facilitates the formation of coordinate Cr(III)-DNA complexes.","Impairment of chromium-DNA adduct formation by hypoxia Abs: The reduction of hexavalent chromium [Cr(VI)] generates several genetic lesions. While mechanisms include both direct metal-DNA interactions and the generation of radical intermediates, the precise role of oxygen in this process is unclear. We studied the formation of Cr-induced lesions in DNA in vitro reacted with either Cr(VI) and ascorbic acid (Asc), or Cr(III), under both ambient and hypoxic conditions. Hypoxia had no effect on the kinetics of Cr(VI) reduction by Asc, but decreased, by ~50%, the levels of Cr(VI)/Asc-induced Cr-DNA adducts and DNA polymerase-arresting lesions (PALs) following a 2 hour treatment. In addition, hypoxia impaired the formation of Cr-induced DNA interstrand crosslinks by ~2-fold in plasmid DNA treated with Cr(VI)/Asc. Although the effects of oxygen deprivation were pronounced after 2 hours; following a 20 hour incubation of DNA with Cr(VI)/Asc, Cr-DNA adduct levels were again similar under both ambient and hypoxic conditions indicating that hypoxia reduced the rate at which Cr interacted with DNA, but not the ultimate steady state level of Cr-DNA binding. The inhibitory effect of hypoxia on Cr(VI)/Asc genotoxicity could not be explained by alterations in the reactivity of intermediate Cr species [i.e. Cr(V)] because Cr(III)-induced DNA damage (adducts, PALs, ICLs) was also impaired by hypoxia. Moreover, the production of Cr(V), as detected by electron spin resonance (ESR), was similar in ambient and hypoxic reactions. These effects were specific for Cr(III) because hypoxia did not affect the generation of ICLs by cisplatin, another inorganic DNA crosslinking agent. Taken together, the results from this study reveal a novel oxygen-dependent step in Cr genotoxicity wherein molecular oxygen facilitates the formation of coordinate Cr(III)-DNA complexes."
1290453,O’Hara and  Klei 2005,Chromium(VI) Activates Stat3 In Bronchial Epithelial Cells,"Inhaled hexavalent chromium (Cr(VI)) promotes pulmonary diseases through poorly defined mechanisms, and modification of signaling proteins may play a significant role in this etiology. Although several transcription factors have been demonstrated to respond to Cr(VI) exposures, most studies have focused solely on acute changes in NF-kappaB or NF-kappaB in combination with activator protein-1 (AP-1). Thus, we hypothesized that non-cytotoxic levels of Cr(VI) may promote pulmonary disease by increasing Stat activity in bronchial epithelial cells (BEAS-2B). A 24 h Cr(VI) (5 µM) exposure caused an 8.5-fold increase in nuclear protein binding to the Stat5 cis-response element. To validate this finding, BEAS-2B cells were exposed to Cr(VI) for 1, 4 and 24 h. Cr(VI) caused a transient activation of Stat1 at 1 h that was diminished by 4 h. Stat3 remained phosphorylated after 4 h while Stat5 was not activated at any of the time-points. Sub-chronic investigations were initiated to mimic realistic exposure times. After 24, 48, and 72 h, Cr(VI) increased nuclear levels of phosphorylated Stat3, minimally activated Stat1, and had no effect on Stat5. Immunofluorescence microscopy confirmed that Cr(VI) increased nuclear levels of phosphorylated Stat3. Inhibition of Lck, a Src family kinase, with specific siRNA sequences caused a 2-fold reduction in Cr(VI)-induced Stat3 phosphorylation. These data suggest that Cr(VI) activates tyrosine kinases to effect longterm shifts in transcription factor signaling and gene expression, which may underlie disease prone phenotypes in lung epithelium.","Chromium(VI) Activates Stat3 In Bronchial Epithelial Cells Abs: Inhaled hexavalent chromium (Cr(VI)) promotes pulmonary diseases through poorly defined mechanisms, and modification of signaling proteins may play a significant role in this etiology. Although several transcription factors have been demonstrated to respond to Cr(VI) exposures, most studies have focused solely on acute changes in NF-kappaB or NF-kappaB in combination with activator protein-1 (AP-1). Thus, we hypothesized that non-cytotoxic levels of Cr(VI) may promote pulmonary disease by increasing Stat activity in bronchial epithelial cells (BEAS-2B). A 24 h Cr(VI) (5 µM) exposure caused an 8.5-fold increase in nuclear protein binding to the Stat5 cis-response element. To validate this finding, BEAS-2B cells were exposed to Cr(VI) for 1, 4 and 24 h. Cr(VI) caused a transient activation of Stat1 at 1 h that was diminished by 4 h. Stat3 remained phosphorylated after 4 h while Stat5 was not activated at any of the time-points. Sub-chronic investigations were initiated to mimic realistic exposure times. After 24, 48, and 72 h, Cr(VI) increased nuclear levels of phosphorylated Stat3, minimally activated Stat1, and had no effect on Stat5. Immunofluorescence microscopy confirmed that Cr(VI) increased nuclear levels of phosphorylated Stat3. Inhibition of Lck, a Src family kinase, with specific siRNA sequences caused a 2-fold reduction in Cr(VI)-induced Stat3 phosphorylation. These data suggest that Cr(VI) activates tyrosine kinases to effect longterm shifts in transcription factor signaling and gene expression, which may underlie disease prone phenotypes in lung epithelium."
1290452,O’Hara et al. 2004,Selective signaling pathways for chromium(VI) induced patterns of transcription factor binding in exposed airway epithelial cells,"Inhaled hexavalent chromium (Cr(VI)) promotes pulmonary disease and lung cancer through poorly defined mechanisms. To explore these potential mechanisms, Beas-2B airway epithelial cells were used to investigate the hypothesis that nontoxic Cr(VI) exposures selectively activate cell signaling pathways which lead to changes in the profile of transcription factor binding to specific cis-elements in DNA. These studies demonstrated that non-toxic doses (1-5 µM) of Cr(VI) increased the abundance of tyrosine kinases. Two of these kinases, bone marrow X kinase (Bmx) and focal adhesion kinase (Fak), were detected by western blot analysis, and protein tyrosine kinase 2 (Pyk2) was detected by a Kinetworks™ protein kinase screen. As the levels of Pyk2 increased, so did its association with Fyn, a Src family kinase member. Futher, the kinase activities of both Fyn and Lck increased in response to Cr(VI). The DNA binding of various transcription factors (TF) are responsive to upstream signaling cascades that are altered in response to Cr(VI). Two protein/DNA array systems were used to demonstrate that protein binding to 9 out of a total of 150 targeted cis-elements changed over a 24 h exposure period. Significant increases were seen in both Stat 5 and AP-1 binding, which may be related to activation of tyrosine kinase activity by Cr(VI). The most significant decrease was seen in the level of nuclear protein that binds to the antioxidant/electrophile response element (ARE). These findings suggest that airway cell phenotype may be changed as low concentrations of Cr(VI) selectively activate signaling pathways that lead to prolonged changes in transcription factor binding.","Selective signaling pathways for chromium(VI) induced patterns of transcription factor binding in exposed airway epithelial cells Abs: Inhaled hexavalent chromium (Cr(VI)) promotes pulmonary disease and lung cancer through poorly defined mechanisms. To explore these potential mechanisms, Beas-2B airway epithelial cells were used to investigate the hypothesis that nontoxic Cr(VI) exposures selectively activate cell signaling pathways which lead to changes in the profile of transcription factor binding to specific cis-elements in DNA. These studies demonstrated that non-toxic doses (1-5 µM) of Cr(VI) increased the abundance of tyrosine kinases. Two of these kinases, bone marrow X kinase (Bmx) and focal adhesion kinase (Fak), were detected by western blot analysis, and protein tyrosine kinase 2 (Pyk2) was detected by a Kinetworks™ protein kinase screen. As the levels of Pyk2 increased, so did its association with Fyn, a Src family kinase member. Futher, the kinase activities of both Fyn and Lck increased in response to Cr(VI). The DNA binding of various transcription factors (TF) are responsive to upstream signaling cascades that are altered in response to Cr(VI). Two protein/DNA array systems were used to demonstrate that protein binding to 9 out of a total of 150 targeted cis-elements changed over a 24 h exposure period. Significant increases were seen in both Stat 5 and AP-1 binding, which may be related to activation of tyrosine kinase activity by Cr(VI). The most significant decrease was seen in the level of nuclear protein that binds to the antioxidant/electrophile response element (ARE). These findings suggest that airway cell phenotype may be changed as low concentrations of Cr(VI) selectively activate signaling pathways that lead to prolonged changes in transcription factor binding."
1290451,Anonymous 1999,Chromium,"Canadian ISQGs and PELs for Cr were developed using a modification of the National Status and Trends Program approach as described in CCME (1995) (Table 1). The ISQGs and PELs refer to total concentrations of Cr in surficial sediments (i.e., top 5 cm), as quantified by digestion with a strong acid (e.g., aqua regia, nitric acid, and hydrochloric acid) followed with determination by a standard analytical protocol. Table 1. Interim sediment quality guidelines (ISQGs) and probable effect levels (PELs) for chromium (mg x kg-1 dw). Freshwater, Marine/estuarine ISQG 37.3, 52.3 PEL 90.0, 160 Currently, the degree to which Cr will be bioavailable at particular sites cannot be predicted conclusively from the physicochemical characteristics of the sediments or the attributes of endemic organisms (Environment Canada 1998). Nonetheless, the incidence of adverse biological effects associated with exposure to Cr increases as concentrations of Cr increase in a range of sediment types (Figures 1 and 2). Therefore, the recommended Canadian ISQGs and PELs for Cr will be useful in assessing the ecotoxicological significance of Cr in sediments.","Chromium Abs: Canadian ISQGs and PELs for Cr were developed using a modification of the National Status and Trends Program approach as described in CCME (1995) (Table 1). The ISQGs and PELs refer to total concentrations of Cr in surficial sediments (i.e., top 5 cm), as quantified by digestion with a strong acid (e.g., aqua regia, nitric acid, and hydrochloric acid) followed with determination by a standard analytical protocol. Table 1. Interim sediment quality guidelines (ISQGs) and probable effect levels (PELs) for chromium (mg x kg-1 dw). Freshwater, Marine/estuarine ISQG 37.3, 52.3 PEL 90.0, 160 Currently, the degree to which Cr will be bioavailable at particular sites cannot be predicted conclusively from the physicochemical characteristics of the sediments or the attributes of endemic organisms (Environment Canada 1998). Nonetheless, the incidence of adverse biological effects associated with exposure to Cr increases as concentrations of Cr increase in a range of sediment types (Figures 1 and 2). Therefore, the recommended Canadian ISQGs and PELs for Cr will be useful in assessing the ecotoxicological significance of Cr in sediments."
1290450,Anonymous 1999,"Chromium; Hexavalent Chromium, Trivalent Chromium","Freshwater Life. Hexavalent Chromium. The water quality guideline for hexavalent chromium [Cr(VI)] for the protection of freshwater life is 1.0 ug x L-1 (ix., 0.001 mg x L-1). It was derived by multiplying the 14-d LOEC of 0.01 mg x L-1 for C. dubia (Hickey 1989) by a safety factor of 0.1 (CCME 1991). Trivalent Chromium. The interim water quality guideline for trivalent chromium [Cr(III)] for the protection of freshwater life is 8.9 ug x L-1. It was derived by multiplying the 102-d LOEC (mortality) of 0.089 mg x L-1 for O. mykiss (Stevens and Chapman 1984) by a safety factor of 0.1 (CCME 1991). Marine Life. Hexavalent Chromium. The water quality guideline for hexavalent chromium [Cr(VI)] for the protection of marine life is 1.5 ug x L-1. It was derived by multiplying the 15-d IC50 reduced growth of 0.015 mg x L-1, (Reidel, 1989) for Prorocentrum mariae L. by a safety factor of 0.1 (CCME 1991). Trivalent Chromium. The interim water quality guideline for trivalent chromium [Cr(111)] for the protection of marine life is 56 ug x L-1 (i.e., 0.056 mg x L-1). It was derived by multiplying the 8-d LOEC (survival and reproduction) of 0.56 mg x L-1 for the invertebrate Tisbe battagliai (Hutchinson et al. 1994) by a safety factor of 0.1 (CCME 1991).","Chromium; Hexavalent Chromium, Trivalent Chromium Abs: Freshwater Life. Hexavalent Chromium. The water quality guideline for hexavalent chromium [Cr(VI)] for the protection of freshwater life is 1.0 ug x L-1 (ix., 0.001 mg x L-1). It was derived by multiplying the 14-d LOEC of 0.01 mg x L-1 for C. dubia (Hickey 1989) by a safety factor of 0.1 (CCME 1991). Trivalent Chromium. The interim water quality guideline for trivalent chromium [Cr(III)] for the protection of freshwater life is 8.9 ug x L-1. It was derived by multiplying the 102-d LOEC (mortality) of 0.089 mg x L-1 for O. mykiss (Stevens and Chapman 1984) by a safety factor of 0.1 (CCME 1991). Marine Life. Hexavalent Chromium. The water quality guideline for hexavalent chromium [Cr(VI)] for the protection of marine life is 1.5 ug x L-1. It was derived by multiplying the 15-d IC50 reduced growth of 0.015 mg x L-1, (Reidel, 1989) for Prorocentrum mariae L. by a safety factor of 0.1 (CCME 1991). Trivalent Chromium. The interim water quality guideline for trivalent chromium [Cr(111)] for the protection of marine life is 56 ug x L-1 (i.e., 0.056 mg x L-1). It was derived by multiplying the 8-d LOEC (survival and reproduction) of 0.56 mg x L-1 for the invertebrate Tisbe battagliai (Hutchinson et al. 1994) by a safety factor of 0.1 (CCME 1991)."
1290447,Anonymous 1991,Chromium,"The Guidelines for Canadian Drinking Water Quality 1978 recommend that the maximum acceptable chromium concentration should not exceed 0.05 mg/L (Health and Welfare Canada 1979a). Of the chromium species normally present in surface water, Cr(III) is essential to humans and animals, whereas CR(VI) has adverse physiological effects (NAS 1977). Because trivalent chromium is unlikely to occur in waters above pH 5, hexavelant chromium in the form of either chromates or dichromates is of greater concern in water supplies because these compounds are quite soluble and mobile in the environment (U.S. EPA 1979). Cr(VI) is not considered to be an essential nutrient, and known harmful effects of chromium in humans are attributed to this form. At 0.05 mg/L, hexavelant chromium has not caused any known harmful effects on the health of humans or other animals (Health and Welfare Canada 1980). To protect fish, the concentration of total chromium should not exceed 0.02 mg/L. To protect the aquatic community, including zooplankton and phytoplankton, the concentration of total chromium should not exceed 2.0 ug/L.","Chromium Abs: The Guidelines for Canadian Drinking Water Quality 1978 recommend that the maximum acceptable chromium concentration should not exceed 0.05 mg/L (Health and Welfare Canada 1979a). Of the chromium species normally present in surface water, Cr(III) is essential to humans and animals, whereas CR(VI) has adverse physiological effects (NAS 1977). Because trivalent chromium is unlikely to occur in waters above pH 5, hexavelant chromium in the form of either chromates or dichromates is of greater concern in water supplies because these compounds are quite soluble and mobile in the environment (U.S. EPA 1979). Cr(VI) is not considered to be an essential nutrient, and known harmful effects of chromium in humans are attributed to this form. At 0.05 mg/L, hexavelant chromium has not caused any known harmful effects on the health of humans or other animals (Health and Welfare Canada 1980). To protect fish, the concentration of total chromium should not exceed 0.02 mg/L. To protect the aquatic community, including zooplankton and phytoplankton, the concentration of total chromium should not exceed 2.0 ug/L."
1290441,Sawyer 1994,Chromium and Its Compounds,"The production, use, and health effects of chromium (7440473) and its compounds were described in this chapter. Chromium and its compounds have extensive applications in almost every industry. The toxic effects of chromium are found to be dependent on its valence. Human disease is associated primarilywith exposure to trivalent and/or hexavalent chromium compounds. The primary routes of human exposures are through the skin and respiratory systems for hexavalent chromium and via ingestion for trivalent chromium. Trivalent chromium is found to accumulate in the liver, spleen, muscle, fat, and bone. An increased risk of lung cancer has been associated with exposure to hexavalentchromium and has been reported to be related to its solubility in tissue fluids. Other health effects attributed to chromium exposure include skin diseases and nephrotoxicity. Specific health hazards of chromite ore and smelter workers, chromium metal and alloy workers, chromyl-chloride (14977618) exposed workers, pigment workers, chromium plating workers, chromium alloy welders, ferrochromium workers, and spray painters were described and discussed.Protective and accident control measures, industrial hygiene considerations, and the effects of environmental exposures were reviewed.","Chromium and Its Compounds Abs: The production, use, and health effects of chromium (7440473) and its compounds were described in this chapter. Chromium and its compounds have extensive applications in almost every industry. The toxic effects of chromium are found to be dependent on its valence. Human disease is associated primarilywith exposure to trivalent and/or hexavalent chromium compounds. The primary routes of human exposures are through the skin and respiratory systems for hexavalent chromium and via ingestion for trivalent chromium. Trivalent chromium is found to accumulate in the liver, spleen, muscle, fat, and bone. An increased risk of lung cancer has been associated with exposure to hexavalentchromium and has been reported to be related to its solubility in tissue fluids. Other health effects attributed to chromium exposure include skin diseases and nephrotoxicity. Specific health hazards of chromite ore and smelter workers, chromium metal and alloy workers, chromyl-chloride (14977618) exposed workers, pigment workers, chromium plating workers, chromium alloy welders, ferrochromium workers, and spray painters were described and discussed.Protective and accident control measures, industrial hygiene considerations, and the effects of environmental exposures were reviewed."
1290438,Ohta and  Inui 1992,Concentration of Accumulated Substances in the Human Lung with Special Regard to the Toxic Effects of Hexavalent Chromium in a Factory Worker,"The levels of accumulated substances in the human lung were examined with special regard to the toxic effects of hexavalent chromium (7440473) (Cr) in a factory worker. An autopsy case of a 54 year (yr) old male employed for 7yr at a chromate manufacturing factory in Tokyo, Japan, was discussed. The cause of death was ischemic heart disease, and there was no history of lung disease. Lesions caused by hexavalent Cr were the perforation of the nasal septum, and grayish yellow liver nodules which were histologically shown to be eosinophilic granulomas containing hexavalent Cr. Cr levels in lungs were determined to be 2.7 milligrams/gram wet tissue, as against control levels of 1.6 milligrams/gram wet tissue in autopsied lungs of unexposed subjects. X-Ray microanalysis and neutron activation analysis showed that Cr, manganese (7439965) and vanadium (7440622) levels in lungs of the chromate factory worker were higher than those in controls. Electron spin resonance showed that free radical levels were higher in the lungs indicating an exposure to airborne free radicals. A mutagenicity test (Ames test) proved negative. Black particulates in the lungs were identified as alpha-quartz (14808607). The authors conclude that Cr and various other inhaled metals accumulate in the lungs.","Concentration of Accumulated Substances in the Human Lung with Special Regard to the Toxic Effects of Hexavalent Chromium in a Factory Worker Abs: The levels of accumulated substances in the human lung were examined with special regard to the toxic effects of hexavalent chromium (7440473) (Cr) in a factory worker. An autopsy case of a 54 year (yr) old male employed for 7yr at a chromate manufacturing factory in Tokyo, Japan, was discussed. The cause of death was ischemic heart disease, and there was no history of lung disease. Lesions caused by hexavalent Cr were the perforation of the nasal septum, and grayish yellow liver nodules which were histologically shown to be eosinophilic granulomas containing hexavalent Cr. Cr levels in lungs were determined to be 2.7 milligrams/gram wet tissue, as against control levels of 1.6 milligrams/gram wet tissue in autopsied lungs of unexposed subjects. X-Ray microanalysis and neutron activation analysis showed that Cr, manganese (7439965) and vanadium (7440622) levels in lungs of the chromate factory worker were higher than those in controls. Electron spin resonance showed that free radical levels were higher in the lungs indicating an exposure to airborne free radicals. A mutagenicity test (Ames test) proved negative. Black particulates in the lungs were identified as alpha-quartz (14808607). The authors conclude that Cr and various other inhaled metals accumulate in the lungs."
1290437,Costa 1993,Molecular targets of nickel and chromium in human and experimental systems,"Water-insoluble nickel compounds tend to be carcinogenic because they enter cells through phagocytosis. Highly water-soluble nickel salts, such as nickel chloride, do not enter cells well and thus are not carcinogenic in vivo. Carcinogenic nickel compounds produce selective damage to heterochromatic regions in Chinese hamster chromosomes, probably because of the high concentration of proteins and amino acids in this highly condensed genetically inactive chromatin region. Bivalent nickel ions are highly affinitive to amino acids as compared with deoxyribonucleic acid (DNA). The interaction with proteins is believed to cause this effect. In addition, when nickel binds to proteins, it can be oxidized, and DNA protein damage ensues. A new method detects DNA-protein cross-links induced by various agents, such as nickel, chromium and cis-platinum. It has demonstrated an increase in DNA-protein cross-links in cultured cells from animals treated with chromate and welders exposed to welding fumes.","Molecular targets of nickel and chromium in human and experimental systems Abs: Water-insoluble nickel compounds tend to be carcinogenic because they enter cells through phagocytosis. Highly water-soluble nickel salts, such as nickel chloride, do not enter cells well and thus are not carcinogenic in vivo. Carcinogenic nickel compounds produce selective damage to heterochromatic regions in Chinese hamster chromosomes, probably because of the high concentration of proteins and amino acids in this highly condensed genetically inactive chromatin region. Bivalent nickel ions are highly affinitive to amino acids as compared with deoxyribonucleic acid (DNA). The interaction with proteins is believed to cause this effect. In addition, when nickel binds to proteins, it can be oxidized, and DNA protein damage ensues. A new method detects DNA-protein cross-links induced by various agents, such as nickel, chromium and cis-platinum. It has demonstrated an increase in DNA-protein cross-links in cultured cells from animals treated with chromate and welders exposed to welding fumes."
1290434,Ohta 1988,Accumulation and Composition of Inhaled Particulates in Human Lungs,"An analysis was made of particulate matter isolated from autopsied human lungs of deceased residents of the Tokyo metropolitan area, to establish a data base of elemental and toxic materials accumulated in lungs. Upper left lung lobes from 108 persons with no history of lung disease were studied. Black powder residues separated from lung tissue were analyzed by scanning and transmission electron microscopy with energy dispersive x-ray analysis, neutron activation, elemental analysis, electron spin resonance and x-ray diffraction. Mutagenicity of black deposits was assessed by the Ames test. Primary pathological results were chronic bronchiolitis, emphysema and pavement epithelium metaplasia and were related to heavy cigarette smoking. There was a significant positive correlation of particulate deposition rate with age. Various elements of natural and artificial environmental origin were detected. A high level of chromium (7440473) was noted in tissue from a chromium worker exposed to hexavalent chromium. Average total carbon (7440440) content was 55 weight percent and did not differ between smokers and nonsmokers. Average elemental carbon content was 39 weight percent. Carbon free radicals were detected and attributed to smoking and soot. Mutagenicity tests revealed one sample positive for both Salmonella-typhimurium (TA-98) and (TA-100), while three samples were positive for (TA-98) only. Alpha-quartz (14808607) was observed in 55 samples, and asbestos (1332214) fibers were observed in three of ten samples analyzed. The latter were identified as chrysotile (12001295) in one sample and tremolite (77536686) and crocidolite (12001284) in another. The author concludes that multiple factors, including cigarette smoking, contribute to pulmonary disease due to environmental substances. These results may be useful in determining factors involved in lung disease caused by deposited particles.","Accumulation and Composition of Inhaled Particulates in Human Lungs Abs: An analysis was made of particulate matter isolated from autopsied human lungs of deceased residents of the Tokyo metropolitan area, to establish a data base of elemental and toxic materials accumulated in lungs. Upper left lung lobes from 108 persons with no history of lung disease were studied. Black powder residues separated from lung tissue were analyzed by scanning and transmission electron microscopy with energy dispersive x-ray analysis, neutron activation, elemental analysis, electron spin resonance and x-ray diffraction. Mutagenicity of black deposits was assessed by the Ames test. Primary pathological results were chronic bronchiolitis, emphysema and pavement epithelium metaplasia and were related to heavy cigarette smoking. There was a significant positive correlation of particulate deposition rate with age. Various elements of natural and artificial environmental origin were detected. A high level of chromium (7440473) was noted in tissue from a chromium worker exposed to hexavalent chromium. Average total carbon (7440440) content was 55 weight percent and did not differ between smokers and nonsmokers. Average elemental carbon content was 39 weight percent. Carbon free radicals were detected and attributed to smoking and soot. Mutagenicity tests revealed one sample positive for both Salmonella-typhimurium (TA-98) and (TA-100), while three samples were positive for (TA-98) only. Alpha-quartz (14808607) was observed in 55 samples, and asbestos (1332214) fibers were observed in three of ten samples analyzed. The latter were identified as chrysotile (12001295) in one sample and tremolite (77536686) and crocidolite (12001284) in another. The author concludes that multiple factors, including cigarette smoking, contribute to pulmonary disease due to environmental substances. These results may be useful in determining factors involved in lung disease caused by deposited particles."
1290433,Xianglin and  Dalal 1988,Evidence for Free Radical Involvement in the Toxicity and Carcinogenicity of Chromate Dusts,"Electron spin resonance (ESR) and spin trap methodology were used to investigate the reduction of chromate (13907454) by glutathione (GSH) and find evidence for the involvement of the glutathionyl (GS) radical as well as chromate-V (Cr(V)) intermediates. While an aqueous solution of 0.1 molar spin trap alpha-(4-pyridyl-1-oxide)-N-tert-butylnitrone (4-POBN) containing either chromate or GSH alone did not give any ESR signal, mixtures of chromate, GSH, and 4-POBN together gave a spectrum which was a composite of the spin adduct signal and those of Cr(V). About 10 minutes later, when the signal from Cr(V) had decayed, a clear spectrum (at g of 2.0061) consisting of only doublets of triplets was obtained and was assigned to the 4-POBN-GS adduct. The GS radical had been produced via reaction of GSH with alpha-chromanoxyl radical. Spin trap studies with 5,5-dimethyl-1-pyrroline-1-oxide (DMPO) provided additional support for the identification. The spin trap studies indicated that an increase in the amount of GSH caused an increase in the spin adduct ESR signals until the intensity leveled off at a molar ratio of about 15 to 1 of GSH to potassium-chromate (7789006). The authors conclude that the results of the GS radical and Cr(V) at high GSH levels suggests that the synergistic reaction of the Cr(V) intermediate and the GS radical are perhaps responsible for the increased chromate-IV induced DNA strand breaks at high GSH levels.","Evidence for Free Radical Involvement in the Toxicity and Carcinogenicity of Chromate Dusts Abs: Electron spin resonance (ESR) and spin trap methodology were used to investigate the reduction of chromate (13907454) by glutathione (GSH) and find evidence for the involvement of the glutathionyl (GS) radical as well as chromate-V (Cr(V)) intermediates. While an aqueous solution of 0.1 molar spin trap alpha-(4-pyridyl-1-oxide)-N-tert-butylnitrone (4-POBN) containing either chromate or GSH alone did not give any ESR signal, mixtures of chromate, GSH, and 4-POBN together gave a spectrum which was a composite of the spin adduct signal and those of Cr(V). About 10 minutes later, when the signal from Cr(V) had decayed, a clear spectrum (at g of 2.0061) consisting of only doublets of triplets was obtained and was assigned to the 4-POBN-GS adduct. The GS radical had been produced via reaction of GSH with alpha-chromanoxyl radical. Spin trap studies with 5,5-dimethyl-1-pyrroline-1-oxide (DMPO) provided additional support for the identification. The spin trap studies indicated that an increase in the amount of GSH caused an increase in the spin adduct ESR signals until the intensity leveled off at a molar ratio of about 15 to 1 of GSH to potassium-chromate (7789006). The authors conclude that the results of the GS radical and Cr(V) at high GSH levels suggests that the synergistic reaction of the Cr(V) intermediate and the GS radical are perhaps responsible for the increased chromate-IV induced DNA strand breaks at high GSH levels."
1290427,Beyersmann 1989,Biochemical Speciation in Chromium Genotoxicity,"The biochemical speciation of compounds of chromium (7440473) in mammalian cells was reviewed with respect to uptake, metabolism, DNA binding, and DNA damage. Studies have indicated that hexavalent chromium (Cr(VI)) is taken up rapidly, accumulating intracellularly after its reduction. Trivalent chromium (Cr(III)) is taken up about three orders of magnitude more slowly than the hexavalent compounds. Metabolism of Cr(VI) to Cr(III) compounds passes through the Cr(V) compounds by electron donation. Chromatin in isolated cell nuclei is bound by chromium from various Cr(III) sources, but not chromate. Rat liver and kidney demonstrate DNA/protein crosslinks and DNA strand breaks after chromate administration. These are also found in-vitro when Cr(III) compounds interact with isolated nuclei. Three out of four tested Cr(III) complexes were mutagenic in the Chinese-hamster cell HGPRT mutation assay. Neither chromate nor the four Cr(III) compounds tested caused nicks in a direct DNA strand break assay with supercoiled bacteriophage PM2 DNA. The combined action of chromate plus glutathione as well as the isolated complex of pentavalent chromium did cause DNA breaks. The ultimate DNA nicking agents in the assay were reactive oxygen species. The author concludes that there appeared to be two mechanisms of chromate genotoxicity. One of these involved direct damage to the DNA caused by Cr(V) species. The other mechanism involved DNA/protein crosslinks formed with Cr(III) which is the final reduction state of chromate.","Biochemical Speciation in Chromium Genotoxicity Abs: The biochemical speciation of compounds of chromium (7440473) in mammalian cells was reviewed with respect to uptake, metabolism, DNA binding, and DNA damage. Studies have indicated that hexavalent chromium (Cr(VI)) is taken up rapidly, accumulating intracellularly after its reduction. Trivalent chromium (Cr(III)) is taken up about three orders of magnitude more slowly than the hexavalent compounds. Metabolism of Cr(VI) to Cr(III) compounds passes through the Cr(V) compounds by electron donation. Chromatin in isolated cell nuclei is bound by chromium from various Cr(III) sources, but not chromate. Rat liver and kidney demonstrate DNA/protein crosslinks and DNA strand breaks after chromate administration. These are also found in-vitro when Cr(III) compounds interact with isolated nuclei. Three out of four tested Cr(III) complexes were mutagenic in the Chinese-hamster cell HGPRT mutation assay. Neither chromate nor the four Cr(III) compounds tested caused nicks in a direct DNA strand break assay with supercoiled bacteriophage PM2 DNA. The combined action of chromate plus glutathione as well as the isolated complex of pentavalent chromium did cause DNA breaks. The ultimate DNA nicking agents in the assay were reactive oxygen species. The author concludes that there appeared to be two mechanisms of chromate genotoxicity. One of these involved direct damage to the DNA caused by Cr(V) species. The other mechanism involved DNA/protein crosslinks formed with Cr(III) which is the final reduction state of chromate."
1290423,Stern 1986,"Occupational Exposures, Delivered Doses and Exposure Limits for Chromium and Nickel","The absolute toxicity and transformation potency of a series of chromium (7440473) and nickel (7440020) compounds, as well as industrial metallic aerosols including welding fumes both containing and not containing these metals were reviewed. The BHK-21 mammalian cell in-vitro transformation assay, with modifications to allow analysis of particulates, was used. All nickel compounds tested, including metal particulates, were both toxic and capable of induction of transformation in the bioassay. No increases in toxicity or transformation were observed beyond 6 hours exposure for particulates, indicating that the uptake pathway was phagocytosis. Response to nickel-acetate (373024) increased with time suggesting uptake by membrane permeability. Hexavalent chromium compounds exhibited similar behavior to the tested nickel compounds. Neither chromium metal nor trivalent chromium was toxic or capable of inducing transformation. All 23 welding fumes tested were found to be toxic in the BHK-21 assay, although only fumes containing nickel or hexavalent chromium were transforming.","Occupational Exposures, Delivered Doses and Exposure Limits for Chromium and Nickel Abs: The absolute toxicity and transformation potency of a series of chromium (7440473) and nickel (7440020) compounds, as well as industrial metallic aerosols including welding fumes both containing and not containing these metals were reviewed. The BHK-21 mammalian cell in-vitro transformation assay, with modifications to allow analysis of particulates, was used. All nickel compounds tested, including metal particulates, were both toxic and capable of induction of transformation in the bioassay. No increases in toxicity or transformation were observed beyond 6 hours exposure for particulates, indicating that the uptake pathway was phagocytosis. Response to nickel-acetate (373024) increased with time suggesting uptake by membrane permeability. Hexavalent chromium compounds exhibited similar behavior to the tested nickel compounds. Neither chromium metal nor trivalent chromium was toxic or capable of inducing transformation. All 23 welding fumes tested were found to be toxic in the BHK-21 assay, although only fumes containing nickel or hexavalent chromium were transforming."
1290422,Anonymous 1986,Diseases Caused by Chromium and Its Toxic Compounds,"Diseases caused by exposure to chromium (7440473) or chromium compounds were reviewed. According to the authors, exposure to chromium and its compounds may occur in the metallurgical and chemical industries during the production and use of chromium pigments, in leather tanning and chromium plating, as well as during the production of chromium alloys and stainless steel. Cement also contains small amounts of chromium. Welders, furniture polishers, printers, and photographic technicians may also be exposed. The most important route of occupational exposure entry is through the lungs. Particles smaller than 1 micron have maximum alveolar penetration. Acute effects resulting from ingestion of hexavalent chromium include bleeding in the gastrointestinal tract, necrosis of the liver, or tubular necrosis of the kidneys. Chronic effects include ulcerations in the nasal septum leading to perforation, ulcers in the throat and upper airways, skin allergies, and asthmatic reactions. One delayed effect may be the occurrence of bronchogenic cancer following exposure to dichromate and chromium pigments. Complete recovery from skin and mucous membrane ulcerations and even allergic dermatitis may occur if exposure is discontinued. Skin allergy may persist, and perforation of nasal septum and atrophic rhinitis are irreversible. Persons having a history of asthmatic reaction to airborne chromates or of skin reaction are more susceptible than others. Control measures, including the use of personal protective equipment, should be considered.","Diseases Caused by Chromium and Its Toxic Compounds Abs: Diseases caused by exposure to chromium (7440473) or chromium compounds were reviewed. According to the authors, exposure to chromium and its compounds may occur in the metallurgical and chemical industries during the production and use of chromium pigments, in leather tanning and chromium plating, as well as during the production of chromium alloys and stainless steel. Cement also contains small amounts of chromium. Welders, furniture polishers, printers, and photographic technicians may also be exposed. The most important route of occupational exposure entry is through the lungs. Particles smaller than 1 micron have maximum alveolar penetration. Acute effects resulting from ingestion of hexavalent chromium include bleeding in the gastrointestinal tract, necrosis of the liver, or tubular necrosis of the kidneys. Chronic effects include ulcerations in the nasal septum leading to perforation, ulcers in the throat and upper airways, skin allergies, and asthmatic reactions. One delayed effect may be the occurrence of bronchogenic cancer following exposure to dichromate and chromium pigments. Complete recovery from skin and mucous membrane ulcerations and even allergic dermatitis may occur if exposure is discontinued. Skin allergy may persist, and perforation of nasal septum and atrophic rhinitis are irreversible. Persons having a history of asthmatic reaction to airborne chromates or of skin reaction are more susceptible than others. Control measures, including the use of personal protective equipment, should be considered."
1290421,Beyersmann and  Koster 1987,On the role of trivalent chromium in chromium genotoxicity,"The role of trivalent-chromium (16065831) (Cr+3) in chromium (7440473) genotoxicity is discussed. Chromate ions are taken up efficiently through cell membranes where they are reduced intracellularly to Cr+3 compounds. The reducing agents may be thiol compounds, reducing sugars, or reducing enzymes with their respective coenzymes. The chromate to Cr+3 reduction proceeds through a series of one electron transfer steps, from hexavalent-chromium (18540299) (Cr+6) to Cr+3. After Cr+6 uptake, Cr+3 may accumulate within the cell as much as several hundred fold due to its low membrane permeability. This creates a high chemical potential for intracellular reactions involving Cr+3. Reactions may also occur with DNA. Studies with isolated mammalian cell nuclei have shown cross linking of DNA and protein and DNA strand breakage by Cr+3 compounds. Uptake studies of Cr+3 complexes in mammalian cells indicate that complexes containing hydrophobic ligands such as phenanthroline and pyridine are taken up the most rapidly. Cr+3 compounds do not generally cause DNA lesions within intact cells because of their lack of penetration. The membrane penetrating dichlorophenanthrolinor+3 complex has been shown to cause DNA damage in cultured hamster V79 cells. Cr+3 species that penetrate the cellular membrane induce gene mutations in bacterial, yeast, and mammalian cells. The authors conclude that Cr+3 is probably the ultimate genotoxic form of chromium, although DNA damage by other oxidation states, such as pentavalent-chromium, tetravalent-chromium, or reactive oxidized metabolites cannot be ruled out.","On the role of trivalent chromium in chromium genotoxicity Abs: The role of trivalent-chromium (16065831) (Cr+3) in chromium (7440473) genotoxicity is discussed. Chromate ions are taken up efficiently through cell membranes where they are reduced intracellularly to Cr+3 compounds. The reducing agents may be thiol compounds, reducing sugars, or reducing enzymes with their respective coenzymes. The chromate to Cr+3 reduction proceeds through a series of one electron transfer steps, from hexavalent-chromium (18540299) (Cr+6) to Cr+3. After Cr+6 uptake, Cr+3 may accumulate within the cell as much as several hundred fold due to its low membrane permeability. This creates a high chemical potential for intracellular reactions involving Cr+3. Reactions may also occur with DNA. Studies with isolated mammalian cell nuclei have shown cross linking of DNA and protein and DNA strand breakage by Cr+3 compounds. Uptake studies of Cr+3 complexes in mammalian cells indicate that complexes containing hydrophobic ligands such as phenanthroline and pyridine are taken up the most rapidly. Cr+3 compounds do not generally cause DNA lesions within intact cells because of their lack of penetration. The membrane penetrating dichlorophenanthrolinor+3 complex has been shown to cause DNA damage in cultured hamster V79 cells. Cr+3 species that penetrate the cellular membrane induce gene mutations in bacterial, yeast, and mammalian cells. The authors conclude that Cr+3 is probably the ultimate genotoxic form of chromium, although DNA damage by other oxidation states, such as pentavalent-chromium, tetravalent-chromium, or reactive oxidized metabolites cannot be ruled out."
1290420,Leonard 1986,Chromosome Damage in Individuals Exposed to Heavy Metals,"Chromosome damage in individuals exposed to heavy metals was reviewed. Production of cytogenetic changes in the peripheral blood lymphocytes was discussed in terms of the general characteristics of the peripheral blood lymphocyte system, structural chromosome anomalies produced by clastogens, sister chromatid exchanges, and drawbacks of the cytogenetic analysis in cultured lymphocytes. Results were presented of the cytogenetic monitoring performed on persons exposed to the following: arsenic (7440382), lead (7439921), cadmium (7440439), chromium (7440473), mercury (7439976), nickel (7440020), and various other metals. In addition to their general cytotoxic action causing denaturation of macromolecules, some metals may enter into competition with an essential metal needed to stabilize the structure of a biomolecule. Toxic studies on cultured cells have shown that only arsenic and hexavalent chromium display obvious clastogenic properties in-vitro, whereas no conclusive results have been obtained with the salts of cadmium, lead, mercury and nickel. Results have been confirmed in-vivo in experimental animals. In the sister chromatid exchange test in-vitro, a positive response was obtained with arsenic, chromium, nickel and lead salts, whereas mercury gave negative results. The authors conclude that the observations performed on peripheral blood lymphocytes of people professionally or accidentally exposed to heavy metals very often appear contradictory. Most people are exposed to a mixture of environmental mutagenic agents, not to a single metal, making it difficult to establish cause and effect relationships.","Chromosome Damage in Individuals Exposed to Heavy Metals Abs: Chromosome damage in individuals exposed to heavy metals was reviewed. Production of cytogenetic changes in the peripheral blood lymphocytes was discussed in terms of the general characteristics of the peripheral blood lymphocyte system, structural chromosome anomalies produced by clastogens, sister chromatid exchanges, and drawbacks of the cytogenetic analysis in cultured lymphocytes. Results were presented of the cytogenetic monitoring performed on persons exposed to the following: arsenic (7440382), lead (7439921), cadmium (7440439), chromium (7440473), mercury (7439976), nickel (7440020), and various other metals. In addition to their general cytotoxic action causing denaturation of macromolecules, some metals may enter into competition with an essential metal needed to stabilize the structure of a biomolecule. Toxic studies on cultured cells have shown that only arsenic and hexavalent chromium display obvious clastogenic properties in-vitro, whereas no conclusive results have been obtained with the salts of cadmium, lead, mercury and nickel. Results have been confirmed in-vivo in experimental animals. In the sister chromatid exchange test in-vitro, a positive response was obtained with arsenic, chromium, nickel and lead salts, whereas mercury gave negative results. The authors conclude that the observations performed on peripheral blood lymphocytes of people professionally or accidentally exposed to heavy metals very often appear contradictory. Most people are exposed to a mixture of environmental mutagenic agents, not to a single metal, making it difficult to establish cause and effect relationships."
1290419,Beyersmann et al. 1984,Model reactions of chromium compounds with mammalian and bacterial cells,"Chromate uptake, reduction, cytotoxicity and mutagenicity were studied with human red blood cells, Chinese hamster ovary (CHO) cells and/or Salmonella typhimurium mutant cells. All cell types rapidly took up chromates whereas chromium(III) salts were excluded under the experimental conditions. Red blood cells reduced and accumulated chromium from chromate. At concentrations above 0.1 mM, chromate inactivated the red cell chromate carrier. Chromate above 0.01 mM inhibited CHO cell proliferation irrespective of the cations present. Chromate and two chromium(III) complexes were mutagenic with Salmonella mutants in the Ames’ assay. A model for chromate metabolism and genotoxicity is proposed.","Model reactions of chromium compounds with mammalian and bacterial cells Abs: Chromate uptake, reduction, cytotoxicity and mutagenicity were studied with human red blood cells, Chinese hamster ovary (CHO) cells and/or Salmonella typhimurium mutant cells. All cell types rapidly took up chromates whereas chromium(III) salts were excluded under the experimental conditions. Red blood cells reduced and accumulated chromium from chromate. At concentrations above 0.1 mM, chromate inactivated the red cell chromate carrier. Chromate above 0.01 mM inhibited CHO cell proliferation irrespective of the cations present. Chromate and two chromium(III) complexes were mutagenic with Salmonella mutants in the Ames’ assay. A model for chromate metabolism and genotoxicity is proposed."
1290417,Skaug et al. 1985,In Vitro Cytotoxicity of Fibrous and Non-Fibrous Lead Chromate Particles in Human Bronchial Epithelial Cells and Rat Alveolar Macrophages,"The cytotoxic effects of fibrous (FLC) and nonfibrous (NFLC) lead-chromate (7758976) particles were investigated in two different in-vitro assays: human bronchial epithelial cells (HBE) from normal adult autopsy tissue, and Wistar-rat alveolar macrophages (AM). Particle solubility was dependent on medium composition and time. As measured by the depression of clonal growth rate as a function of dose, the 50 percent cytotoxic dose for HBE cells was 100 and 250 micrograms/milliliter for FLC and NFLC, respectively. Sodium-chromate (7775113) produced dose dependent cytotoxicity on AM and caused a much greater release of lactate-dehydrogenase from these cells. The cytotoxic effects of FLC and NFLC on rat AM did not differ significantly from each other. Scanning transmission electron microscopy revealed that FLC were ingested by HBE cells, being located primarily within the cytoplasm. The authors conclude that lead-chromate fibers less than 5 microns in length and 0.1 to 0.2 microns in width and nonfibrous lead-chromate do not seem to induce any profound acute effect on AM membranes.","In Vitro Cytotoxicity of Fibrous and Non-Fibrous Lead Chromate Particles in Human Bronchial Epithelial Cells and Rat Alveolar Macrophages Abs: The cytotoxic effects of fibrous (FLC) and nonfibrous (NFLC) lead-chromate (7758976) particles were investigated in two different in-vitro assays: human bronchial epithelial cells (HBE) from normal adult autopsy tissue, and Wistar-rat alveolar macrophages (AM). Particle solubility was dependent on medium composition and time. As measured by the depression of clonal growth rate as a function of dose, the 50 percent cytotoxic dose for HBE cells was 100 and 250 micrograms/milliliter for FLC and NFLC, respectively. Sodium-chromate (7775113) produced dose dependent cytotoxicity on AM and caused a much greater release of lactate-dehydrogenase from these cells. The cytotoxic effects of FLC and NFLC on rat AM did not differ significantly from each other. Scanning transmission electron microscopy revealed that FLC were ingested by HBE cells, being located primarily within the cytoplasm. The authors conclude that lead-chromate fibers less than 5 microns in length and 0.1 to 0.2 microns in width and nonfibrous lead-chromate do not seem to induce any profound acute effect on AM membranes."
1290415,Shifrine et al. 1984,"Effect Of Trace Elements Found In Coal Fly Ash, On Lymphocyte Blastogenesis","The effects of trace elements found in coal fly ash on peripheral blood lymphocyte functions were investigated. The lectin induced whole blood lymphocyte stimulation test was employed. Trace element concentrations approximating concentrations found in a macrophage that had phagocytized 1 or 10 fly ash particles with an average diameter of the finest fly ash fraction were used. Of the 16 trace elements tested only arsenic(III) (22541544), selenium (7782492), vanadium (7440622), copper (7440508), and manganese (7439965) exhibited 50 percent inhibition of lymphocyte division at concentrations equivalent to or less than 10 fly ash particles per macrophage. Additions of lower concentrations of arsenic, 0.05 microgram/milliliter (microg/ml), or selenium, 0.03microg/ml, resulted in an apparent stimulation of the mitogen induced blastogenesis, but greater concentrations produced a dramatic decrease in lymphocyte blastogenesis. For vanadium the concentrations which produced 50 percent inhibition of blastogenesis were approximately 10 percent of the calculated exposure that would result from a single fly ash particle per cell. Toxicity from cadmium (7440439) and beryllium (7440417) exposures was apparent only at concentrations somewhat higher than the 10 particle equivalent dose. The other trace elements, chromium(III) (16065831), chromium(IV) (18540299), barium (7440393), molybdenum (7439987), nickel (7440020), lead (7439921), tin (7440315), uranium (7440611), and zinc (7440666) were not toxic in the concentration ranges examined. The authors conclude that the ranking of toxicity of these trace elements by this method in decreasing order is manganese, vanadium, arsenic(III), copper, cadmium, selenium, and beryllium. The whole blood lymphocyte stimulation test is a sensitive and reproducible test for in-vitro screening of trace elements for possible effects on the immune system. Further studies of the chemical form and bioavailability of the elements found toxic in this study in coal fly ash will aid in evaluation of potential health impacts of coal combustion effluents.","Effect Of Trace Elements Found In Coal Fly Ash, On Lymphocyte Blastogenesis Abs: The effects of trace elements found in coal fly ash on peripheral blood lymphocyte functions were investigated. The lectin induced whole blood lymphocyte stimulation test was employed. Trace element concentrations approximating concentrations found in a macrophage that had phagocytized 1 or 10 fly ash particles with an average diameter of the finest fly ash fraction were used. Of the 16 trace elements tested only arsenic(III) (22541544), selenium (7782492), vanadium (7440622), copper (7440508), and manganese (7439965) exhibited 50 percent inhibition of lymphocyte division at concentrations equivalent to or less than 10 fly ash particles per macrophage. Additions of lower concentrations of arsenic, 0.05 microgram/milliliter (microg/ml), or selenium, 0.03microg/ml, resulted in an apparent stimulation of the mitogen induced blastogenesis, but greater concentrations produced a dramatic decrease in lymphocyte blastogenesis. For vanadium the concentrations which produced 50 percent inhibition of blastogenesis were approximately 10 percent of the calculated exposure that would result from a single fly ash particle per cell. Toxicity from cadmium (7440439) and beryllium (7440417) exposures was apparent only at concentrations somewhat higher than the 10 particle equivalent dose. The other trace elements, chromium(III) (16065831), chromium(IV) (18540299), barium (7440393), molybdenum (7439987), nickel (7440020), lead (7439921), tin (7440315), uranium (7440611), and zinc (7440666) were not toxic in the concentration ranges examined. The authors conclude that the ranking of toxicity of these trace elements by this method in decreasing order is manganese, vanadium, arsenic(III), copper, cadmium, selenium, and beryllium. The whole blood lymphocyte stimulation test is a sensitive and reproducible test for in-vitro screening of trace elements for possible effects on the immune system. Further studies of the chemical form and bioavailability of the elements found toxic in this study in coal fly ash will aid in evaluation of potential health impacts of coal combustion effluents."
1290414,Stern 1971,"A Chemical, Physical And Biological Assay Of Welding Fume, Part II: Implications Of Positive Mutagenic Tests","The consequences of positive mutagenic test results in stainless steel welding fumes are reviewed. Biological assays show that stainless steel welding fumes give positive results in the Ames mutagenicity test. Detailed quantitative Ames test results confirm that hexavalent chromium (18540299) (Cr) is an active mutagen in stainless steel welding fumes. There is also evidence that stainless steel welding fumes contain another mutagen, possibly nickel (7440020) (Ni). There is insufficient information about the mutagenic activity of Ni to draw a conclusion. The human carcinogenicity of Cr compounds and the relationship to stainless steel welding are discussed. Manual metal arc stainless steel welding fumes contain 2.2 to 4.3 percent water soluble and 0.03 to 0.42 percent water insoluble Cr. Metal inert gas stainless steel welding fumes contain 0.005 to 0.18 percent water soluble and 0.001 to 0.18 percent water insoluble Cr. Exposure to water insoluble Cr causes an incidence of respiratory cancer 10 to 30 times greater than found in the general population; there is no evidence of an increased cancer risk due to exposure to water soluble Cr. The author recommends that exposure to manual metal arc stainless steel welding fumes be reduced. Mutagenic tests should be considered as alternatives to epidemiological surveys or long term bioassays for carcinogenicity.","A Chemical, Physical And Biological Assay Of Welding Fume, Part II: Implications Of Positive Mutagenic Tests Abs: The consequences of positive mutagenic test results in stainless steel welding fumes are reviewed. Biological assays show that stainless steel welding fumes give positive results in the Ames mutagenicity test. Detailed quantitative Ames test results confirm that hexavalent chromium (18540299) (Cr) is an active mutagen in stainless steel welding fumes. There is also evidence that stainless steel welding fumes contain another mutagen, possibly nickel (7440020) (Ni). There is insufficient information about the mutagenic activity of Ni to draw a conclusion. The human carcinogenicity of Cr compounds and the relationship to stainless steel welding are discussed. Manual metal arc stainless steel welding fumes contain 2.2 to 4.3 percent water soluble and 0.03 to 0.42 percent water insoluble Cr. Metal inert gas stainless steel welding fumes contain 0.005 to 0.18 percent water soluble and 0.001 to 0.18 percent water insoluble Cr. Exposure to water insoluble Cr causes an incidence of respiratory cancer 10 to 30 times greater than found in the general population; there is no evidence of an increased cancer risk due to exposure to water soluble Cr. The author recommends that exposure to manual metal arc stainless steel welding fumes be reduced. Mutagenic tests should be considered as alternatives to epidemiological surveys or long term bioassays for carcinogenicity."
1290412,Anonymous ,IPCS Environmental Health Criteria Chromium,"Environmental occurrence of chromium (7440473) and its health effects is reviewed. Many analytical methods are available for determination of chromium in concentrations of about 0.1 milligrams per kilogram (mg/kg) or greater, and these are briefly described. No satisfactory method for chromium determination at lower concentrations exists. The physical properties of chromium and current approaches to developing more sensitive analytical techniques are outlined. Chromium occurs ubiquitously in nature in concentrations ranging from less than 0.1 micrograms per cubic meter in air to 0.4 percent in some soils. Natural concentrations in uncontaminated waters range from fractions of microgram to a few micrograms per liter. The environmental sources and pathways of chromium are described. Only trivalent-chromium (16065831) and hexavalent-chromium (18540299) are important for health. The trivalent form is an essential nutrient for humans and is relatively nontoxic in humans and other mammals. The hexavalent form may be toxic in concentrations in diet or water exceeding 10mg/kg. It is mutagenic and, with long term exposure in air, carcinogenic. Almost all hexavalent-chromium in the environment is artificially produced. Studies concerning the metabolism of chromium in experimental animals and humans are discussed. Experimental studies describing the toxic effects of hexavalent-chromium and the effects of trivalent-chromium deficiency are presented. Clinical and epidemiological studies in humans are reviewed. The most important clinical features following oral exposure to soluble chromates are liver and kidney necrosis and poisoning of the blood forming organs. Hexavalent-chromium causes marked respiratory tract irritation. Some chromate compounds produce skin irritation and damage. Chronic effects of chromium exposure occur in the lung, liver, kidney, gastrointestinal tract, and circulatory system. The authors conclude that exposure to chromium is only a potential health problem in occupational exposures to hexavalent forms.","IPCS Environmental Health Criteria Chromium Abs: Environmental occurrence of chromium (7440473) and its health effects is reviewed. Many analytical methods are available for determination of chromium in concentrations of about 0.1 milligrams per kilogram (mg/kg) or greater, and these are briefly described. No satisfactory method for chromium determination at lower concentrations exists. The physical properties of chromium and current approaches to developing more sensitive analytical techniques are outlined. Chromium occurs ubiquitously in nature in concentrations ranging from less than 0.1 micrograms per cubic meter in air to 0.4 percent in some soils. Natural concentrations in uncontaminated waters range from fractions of microgram to a few micrograms per liter. The environmental sources and pathways of chromium are described. Only trivalent-chromium (16065831) and hexavalent-chromium (18540299) are important for health. The trivalent form is an essential nutrient for humans and is relatively nontoxic in humans and other mammals. The hexavalent form may be toxic in concentrations in diet or water exceeding 10mg/kg. It is mutagenic and, with long term exposure in air, carcinogenic. Almost all hexavalent-chromium in the environment is artificially produced. Studies concerning the metabolism of chromium in experimental animals and humans are discussed. Experimental studies describing the toxic effects of hexavalent-chromium and the effects of trivalent-chromium deficiency are presented. Clinical and epidemiological studies in humans are reviewed. The most important clinical features following oral exposure to soluble chromates are liver and kidney necrosis and poisoning of the blood forming organs. Hexavalent-chromium causes marked respiratory tract irritation. Some chromate compounds produce skin irritation and damage. Chronic effects of chromium exposure occur in the lung, liver, kidney, gastrointestinal tract, and circulatory system. The authors conclude that exposure to chromium is only a potential health problem in occupational exposures to hexavalent forms."
1290411,Langard and  Hensten-Pettersen 1981,Chromium Toxicology,"The toxicology of chromium (7440473) is reviewed. A survey of food shows that human dietary chromium exposure comes primarily from meat, vegetables, and refined sugar. Environmentally, annual mean values of chromium in urban air for most cases is lower than 10 nanograms per cubic meter. Occupationally, exposure may occur in 81 different occupations. Prime occupational routes are inhalation and skin contact. The metabolism and storage of chromium is examined with respect to uptake and excretion, storage and distribution, transplacental transfer, and intracellular distribution. Chromium concentrations in tissues show considerable geographic and occupational variations. No attempts have been made to establish human tissue concentrations that might be considered normal. Acute toxic effects of chromium, primarily nephrotoxic and hepatotoxic, are rarely seen and the few cases reported have been caused by accidental hexavalent-chromium (18540299) ingestion. Classic subacute effects are skin ulcerations and nasal septum perforation. A carcinogenic effect of dust containing hexavalent-chromium compounds is an increased incidence of bronchial cancer in exposed workers. There seems to be evidence that all hexavalent-chromium compounds should be considered carcinogens, but associations between cancer and chromate exposure can only be determined by epidemiological studies or accurate documentation of working history. Effects of chromium on lung and skin are described. The biochemical aspects of acute toxicity and carcinogenicity are presented. Uses of chromium as alloys in biometals include reactions with cobalt/chromium stainless steel and titanium. Studies show adverse effects such as corrosive chromium release from stainless steel and chromium/cobalt alloys, allergic reactions to prosthesis, and bone sarcoma from chromium containing implants.","Chromium Toxicology Abs: The toxicology of chromium (7440473) is reviewed. A survey of food shows that human dietary chromium exposure comes primarily from meat, vegetables, and refined sugar. Environmentally, annual mean values of chromium in urban air for most cases is lower than 10 nanograms per cubic meter. Occupationally, exposure may occur in 81 different occupations. Prime occupational routes are inhalation and skin contact. The metabolism and storage of chromium is examined with respect to uptake and excretion, storage and distribution, transplacental transfer, and intracellular distribution. Chromium concentrations in tissues show considerable geographic and occupational variations. No attempts have been made to establish human tissue concentrations that might be considered normal. Acute toxic effects of chromium, primarily nephrotoxic and hepatotoxic, are rarely seen and the few cases reported have been caused by accidental hexavalent-chromium (18540299) ingestion. Classic subacute effects are skin ulcerations and nasal septum perforation. A carcinogenic effect of dust containing hexavalent-chromium compounds is an increased incidence of bronchial cancer in exposed workers. There seems to be evidence that all hexavalent-chromium compounds should be considered carcinogens, but associations between cancer and chromate exposure can only be determined by epidemiological studies or accurate documentation of working history. Effects of chromium on lung and skin are described. The biochemical aspects of acute toxicity and carcinogenicity are presented. Uses of chromium as alloys in biometals include reactions with cobalt/chromium stainless steel and titanium. Studies show adverse effects such as corrosive chromium release from stainless steel and chromium/cobalt alloys, allergic reactions to prosthesis, and bone sarcoma from chromium containing implants."
1290408,Merkur'Eva et al. 1982,Comparative study of metabolic reactions in laboratory animals exposed to hexavalent chromium via different routes of administration,Heep copyright: biol abs. note rat dermatitis metal pollution,Comparative study of metabolic reactions in laboratory animals exposed to hexavalent chromium via different routes of administration Abs: Heep copyright: biol abs. note rat dermatitis metal pollution
1290407,Goodgame et al. 1982,Carcinogenic chromium vi forms chromium v with ribo nucleotides but not with deoxy ribo nucleotides,Heep copyright: biol abs. rat liver kidney dna cross linking dna synthesis infidelity,Carcinogenic chromium vi forms chromium v with ribo nucleotides but not with deoxy ribo nucleotides Abs: Heep copyright: biol abs. rat liver kidney dna cross linking dna synthesis infidelity
1290405,Ohta et al. 1980,Distribution of chromium and induction of metallothionein-like protein in rat livers injected with trivalent and hexavalent chromium,"HEEP COPYRIGHT: BIOL ABS. To investigate the movement of trivalent and hexavalent Cr, the distribution of Cr and Zn content in the metallothionein-like protein supernatented fraction of rat liver injected s.c. daily for 4 days with trivalent and hexavalent Cr were examined. The Cr content in liver and in each subcellular fraction (crude nuclei, mitochondria, microsome and supernatent) obtained by centrifugation from the liver homogenate of rat injected with hexavalent Cr (Group-Cr (VI)) were remarkably higher than those of rat liver injected with trivalent Cr (Group-Cr (III)). The Cr distribution in subcellular fractions showed a difference between Group-Cr (III) and Group-Cr (VI). In Group Cr (III)fraction and only 5% in supernatent, while in Group-Cr (VI)2% in nuclear fraction anddria and microsome fractions was the same in both groups. Zn content in metallothionein-like protein of rat liver was higher in Group-Cr (III) than in Group-Cr (VI), though Cr content in liver of Group-Cr (VI) was higher than that of Group-Cr (III). The induction of metallothionein-like protein (Zn-thionein) in liver by trivalent or hexavalent Cr may be different qualitatively and quantitatively.","Distribution of chromium and induction of metallothionein-like protein in rat livers injected with trivalent and hexavalent chromium Abs: HEEP COPYRIGHT: BIOL ABS. To investigate the movement of trivalent and hexavalent Cr, the distribution of Cr and Zn content in the metallothionein-like protein supernatented fraction of rat liver injected s.c. daily for 4 days with trivalent and hexavalent Cr were examined. The Cr content in liver and in each subcellular fraction (crude nuclei, mitochondria, microsome and supernatent) obtained by centrifugation from the liver homogenate of rat injected with hexavalent Cr (Group-Cr (VI)) were remarkably higher than those of rat liver injected with trivalent Cr (Group-Cr (III)). The Cr distribution in subcellular fractions showed a difference between Group-Cr (III) and Group-Cr (VI). In Group Cr (III)fraction and only 5% in supernatent, while in Group-Cr (VI)2% in nuclear fraction anddria and microsome fractions was the same in both groups. Zn content in metallothionein-like protein of rat liver was higher in Group-Cr (III) than in Group-Cr (VI), though Cr content in liver of Group-Cr (VI) was higher than that of Group-Cr (III). The induction of metallothionein-like protein (Zn-thionein) in liver by trivalent or hexavalent Cr may be different qualitatively and quantitatively."
1290404,Koshi 1979,Effects of fume particles from stainless steel welding on sister chromatid exchanges and chromosome aberrations in cultured Chinese hamster cells,"The frequencies of sister chromatid exchanges (SCE) and chromosome aberrations were examined in cultured Chinese hamster (lung) cells (Don) exposed to 2 (mutagenic) fume particles collected from different procedures of stainless steel welding. It was confirmed that the frequencies of SCE and chromosome aberrations in the cells treated with these fume particles increased with increasing fume doses within the range of the fume concentration tested. The fume particles collected from manual metal arc (MMA) welding were more powerful than those from metal inert gas (MIG) welding. To cause the same increase in SCE frequency the fume particles from MIG welding needed to be about 100me particles from MMA welding showed a higher solubility of Cr than those from MIG welding. The amount of dissolved Cr from the former was about 60m was used as a solvent. Small amounts of Mn, Ni, Fe and Mg were also detected in the supernatants of both fume suspensions. There were no significant differences in the amounts of these metals as was found with Cr when comparing MMA welding with MIG welding. The frequencies of SCE and chromosome aberrations were also increased by the addition of the supernatants of these suspensions. Dissolved hexavalent Cr may be involved in the cytogenetic effect of the fume particles from stainless steel welding.","Effects of fume particles from stainless steel welding on sister chromatid exchanges and chromosome aberrations in cultured Chinese hamster cells Abs: The frequencies of sister chromatid exchanges (SCE) and chromosome aberrations were examined in cultured Chinese hamster (lung) cells (Don) exposed to 2 (mutagenic) fume particles collected from different procedures of stainless steel welding. It was confirmed that the frequencies of SCE and chromosome aberrations in the cells treated with these fume particles increased with increasing fume doses within the range of the fume concentration tested. The fume particles collected from manual metal arc (MMA) welding were more powerful than those from metal inert gas (MIG) welding. To cause the same increase in SCE frequency the fume particles from MIG welding needed to be about 100me particles from MMA welding showed a higher solubility of Cr than those from MIG welding. The amount of dissolved Cr from the former was about 60m was used as a solvent. Small amounts of Mn, Ni, Fe and Mg were also detected in the supernatants of both fume suspensions. There were no significant differences in the amounts of these metals as was found with Cr when comparing MMA welding with MIG welding. The frequencies of SCE and chromosome aberrations were also increased by the addition of the supernatants of these suspensions. Dissolved hexavalent Cr may be involved in the cytogenetic effect of the fume particles from stainless steel welding."
1290402,Balakin et al. 1975,The synthesis of ion-exchange polymers and the study of their effect on the absorption of hexavalent chromium from the gastrointestinal tract,"HEEP COPYRIGHT: BIOL ABS. Thirteen ion-exchange polymers were obtained using pyridine, quinoline and pyrocatechin derivatives. In tests on rats given Na251CrO7 (5 muCi) and 0.3 g of an ion-exchange polymer, a number of polymers not only reduced Cr resorption from the gastrointestinal tract, but also reduced its deposition in the liver, skeleton and spleen. These results may be of significance for the treatment of Cr poisoning.","The synthesis of ion-exchange polymers and the study of their effect on the absorption of hexavalent chromium from the gastrointestinal tract Abs: HEEP COPYRIGHT: BIOL ABS. Thirteen ion-exchange polymers were obtained using pyridine, quinoline and pyrocatechin derivatives. In tests on rats given Na251CrO7 (5 muCi) and 0.3 g of an ion-exchange polymer, a number of polymers not only reduced Cr resorption from the gastrointestinal tract, but also reduced its deposition in the liver, skeleton and spleen. These results may be of significance for the treatment of Cr poisoning."
1290399,Hartwig et al. 1990,Use of mammalian short-term tests to study mechanisms of metal genotoxicity,BIOSIS COPYRIGHT: BIOL ABS. RRM ABSTRACT HUMAN HELA CELLS HAMSTER V79 CELLS CADMIUM MANGANESE NICKEL CHROMIUM COBALT DNA MUTAGEN,Use of mammalian short-term tests to study mechanisms of metal genotoxicity Abs: BIOSIS COPYRIGHT: BIOL ABS. RRM ABSTRACT HUMAN HELA CELLS HAMSTER V79 CELLS CADMIUM MANGANESE NICKEL CHROMIUM COBALT DNA MUTAGEN
1290392,Farrell et al. 1988,Genotoxicity of chromium(V) complexes: Possible carcinogenic intermediates of chromium(VI),,Genotoxicity of chromium(V) complexes: Possible carcinogenic intermediates of chromium(VI) Abs: 
1290386,Dudek and  Wetterhahn 1994,Chromium(VI)-induced cytotoxicity and DNA damage occur via two distinct pathways: An oxidative pathway and direct chromium-DNA interaction,,Chromium(VI)-induced cytotoxicity and DNA damage occur via two distinct pathways: An oxidative pathway and direct chromium-DNA interaction Abs: 
1290382,Anon ,Chromic acid,"Data sheet. May enter the body when breathed in and through the skin. It is a carcinogen and a teratogen should be handled with extreme caution. Corrosive effects on the eyes, skin and respiratory tract. May cause a sore or a hole in the wall that separates the two air passages in the nose. May cause skin allergy and damage the liver.","Chromic acid Abs: Data sheet. May enter the body when breathed in and through the skin. It is a carcinogen and a teratogen should be handled with extreme caution. Corrosive effects on the eyes, skin and respiratory tract. May cause a sore or a hole in the wall that separates the two air passages in the nose. May cause skin allergy and damage the liver."
1290379,IARC 1990,"Chromium, nickel and welding","Monographs providing chemical and physical data for chromium and nickel and their compounds, details of production, use, occurrence and analysis, and a review of biological data relevant to the evaluation of carcinogenic risk to humans. It is concluded that chromium (VI) compounds are carcinogenic to humans, while metallic chromium (III) compounds are not classifiable as to their carcinogenicity. Nickel sulfate and combinations of nickel sulfides and oxides are considered to be carcinogenic, while metallic nickel is possibly carcinogenic. The major welding processes are described along with the composition of welding fumes, operational exposures of welders and relevant biological data. Welding fumes are evaluated as being possibly carcinogenic in humans.","Chromium, nickel and welding Abs: Monographs providing chemical and physical data for chromium and nickel and their compounds, details of production, use, occurrence and analysis, and a review of biological data relevant to the evaluation of carcinogenic risk to humans. It is concluded that chromium (VI) compounds are carcinogenic to humans, while metallic chromium (III) compounds are not classifiable as to their carcinogenicity. Nickel sulfate and combinations of nickel sulfides and oxides are considered to be carcinogenic, while metallic nickel is possibly carcinogenic. The major welding processes are described along with the composition of welding fumes, operational exposures of welders and relevant biological data. Welding fumes are evaluated as being possibly carcinogenic in humans."
1290378,Stern et al. 2600,Origin of mutagenicity of welding fumes in S. typhimurium,"The histidine revertant Salmonella microsome test of Ames was used, quantitatively, to determine the origin and extent of mutagenicity in response to exposure to welding fumes. Dose-response experiments and factorial design studies showed that the mutagenic activity was due to the presence of soluble hexavalent chromium (Cr(VI)). A rate of 65|15 revertants per plate and |g Cr(VI) was found for all fumes produced by the MIG welding of stainless steel. A reduced rate was found for manual metal arc welding fumes. The presence of other metals in low oxidation states reduced the amount of Cr(VI) present and caused an accompanying decrease of the revertant rate per unit fumes mass.","Origin of mutagenicity of welding fumes in S. typhimurium Abs: The histidine revertant Salmonella microsome test of Ames was used, quantitatively, to determine the origin and extent of mutagenicity in response to exposure to welding fumes. Dose-response experiments and factorial design studies showed that the mutagenic activity was due to the presence of soluble hexavalent chromium (Cr(VI)). A rate of 65|15 revertants per plate and |g Cr(VI) was found for all fumes produced by the MIG welding of stainless steel. A reduced rate was found for manual metal arc welding fumes. The presence of other metals in low oxidation states reduced the amount of Cr(VI) present and caused an accompanying decrease of the revertant rate per unit fumes mass."
1290377,Santonen et al. 2009,Inorganic chromium(III) compounds,"Conclusions of this criteria document inorganic chromium(III) compounds: Trivalent chromium is considered to be an essential trace element in mammals, being involved in lipid and glucose metabolism. The key end-point considered to be relevant for human exposure to chromium(III) oxide is sustained local irritation and inflammation associated with accumulation of respirable particles in the lungs to the extent that the clearance mechanisms are overloaded. The key end-points relevant for human exposure to basic chromium sulfate, presumed to represent soluble chromium(III) salts as a group, are local respiratory toxicity and sensitization of the skin. Detailed summaries in French and Spanish are included.","Inorganic chromium(III) compounds Abs: Conclusions of this criteria document inorganic chromium(III) compounds: Trivalent chromium is considered to be an essential trace element in mammals, being involved in lipid and glucose metabolism. The key end-point considered to be relevant for human exposure to chromium(III) oxide is sustained local irritation and inflammation associated with accumulation of respirable particles in the lungs to the extent that the clearance mechanisms are overloaded. The key end-points relevant for human exposure to basic chromium sulfate, presumed to represent soluble chromium(III) salts as a group, are local respiratory toxicity and sensitization of the skin. Detailed summaries in French and Spanish are included."
1290375,Trocha et al. 1999,Chromium carcinogenity,"BIOSIS COPYRIGHT: BIOL ABS. Chromium belongs to the group of trace elements hich are essential in numerous functions of the human body. Chromium deficiency may be responsible for various dysfunctions, whereas exposure to chromium at higher concentrations is toxic and may lead to the occurrence of neoplastic diseases. Epidemiological studies of chromium exposure proved its carcinogenity, and thus the IARC recognised Cr(VI) and its compounds as one of ascertained carcinogens. Some findings of these studies were reviewed in t assessment of chromium mutagenity and genotoxicity are also discussed, and special attention is paidto tests of mutation in bacteria and yeast as well as to sister chromatid exchange (SCE) test.","Chromium carcinogenity Abs: BIOSIS COPYRIGHT: BIOL ABS. Chromium belongs to the group of trace elements hich are essential in numerous functions of the human body. Chromium deficiency may be responsible for various dysfunctions, whereas exposure to chromium at higher concentrations is toxic and may lead to the occurrence of neoplastic diseases. Epidemiological studies of chromium exposure proved its carcinogenity, and thus the IARC recognised Cr(VI) and its compounds as one of ascertained carcinogens. Some findings of these studies were reviewed in t assessment of chromium mutagenity and genotoxicity are also discussed, and special attention is paidto tests of mutation in bacteria and yeast as well as to sister chromatid exchange (SCE) test."
1290374,Pritchard et al. 1999,Inhibition of chromium(VI)-induced apoptosis and mitochondrial cytochrome C release in CHO cells by cyclosporin A,Biosis copyright: biol abs. rrm meeting abstract cho cell line cell biology tumor biology apoptosis mitochondria cytochrome c release chromiumvi carcinogen pollutant toxicology,Inhibition of chromium(VI)-induced apoptosis and mitochondrial cytochrome C release in CHO cells by cyclosporin A Abs: Biosis copyright: biol abs. rrm meeting abstract cho cell line cell biology tumor biology apoptosis mitochondria cytochrome c release chromiumvi carcinogen pollutant toxicology
1290373,Toraason 1999,8-Hydroxydeoxyguanosine as a biomarker of workplace exposure,"BIOSIS COPYRIGHT: BIOL ABS. To date, the 8-hydroxydeoxyguanosine (8OHdG) DNA adduct has been used as a biomarker in 11 occupational health studies examining the potential for ten different workplace exposures to cause oxidative DNA damage. Exposures examined include asbestos, azo-dyes, benzene, chromium, coal dust, glassworks, rubber manufacturing, styrene, toluene and environmental tobacco smoke (ETS). Experimental designs that applied 8OHdG as biomarker varied dramatically among the studies. For example, one study detected increased urinary excretion in retired workers with a history of exposure to mining dusts, while a study of workers exposed to benzene showed that the pattern of urinary excretion of 8OHdG varied over a 24 h period following exposure. All but one study reported increased 8OHdG relative to controls, but in three cases the increases were not statistically significant. Only one study demonstrated a dose-response relationship between a chemical exposure (benzene) in the workplace a","8-Hydroxydeoxyguanosine as a biomarker of workplace exposure Abs: BIOSIS COPYRIGHT: BIOL ABS. To date, the 8-hydroxydeoxyguanosine (8OHdG) DNA adduct has been used as a biomarker in 11 occupational health studies examining the potential for ten different workplace exposures to cause oxidative DNA damage. Exposures examined include asbestos, azo-dyes, benzene, chromium, coal dust, glassworks, rubber manufacturing, styrene, toluene and environmental tobacco smoke (ETS). Experimental designs that applied 8OHdG as biomarker varied dramatically among the studies. For example, one study detected increased urinary excretion in retired workers with a history of exposure to mining dusts, while a study of workers exposed to benzene showed that the pattern of urinary excretion of 8OHdG varied over a 24 h period following exposure. All but one study reported increased 8OHdG relative to controls, but in three cases the increases were not statistically significant. Only one study demonstrated a dose-response relationship between a chemical exposure (benzene) in the workplace a"
1290372,Gasiorowski et al. 1998,Genotoxicity of Cr(VI) can be markedly lowered by complexation of the chromate anion,"BIOSIS COPYRIGHT: BIOL ABS. We compared mutagenic activity of Cu(II) chromate complexes with 2,2'-bipyridyl, 1,10-phenanthroline, and 2-(2'-pyridyl)imidazole in the standard bacterial tests. It was noticed that Cu(II) chromate complexes with 2-(2'-pyridyl)imidazole exhibited the lowest mutagenic activity among ten tested complexes. We regard these results as promising for further syntheses of Cr(VI) - organic ligand complexes in the aspects of chromium mutagenicity quenching.","Genotoxicity of Cr(VI) can be markedly lowered by complexation of the chromate anion Abs: BIOSIS COPYRIGHT: BIOL ABS. We compared mutagenic activity of Cu(II) chromate complexes with 2,2'-bipyridyl, 1,10-phenanthroline, and 2-(2'-pyridyl)imidazole in the standard bacterial tests. It was noticed that Cu(II) chromate complexes with 2-(2'-pyridyl)imidazole exhibited the lowest mutagenic activity among ten tested complexes. We regard these results as promising for further syntheses of Cr(VI) - organic ligand complexes in the aspects of chromium mutagenicity quenching."
1290371,Civitello et al. 1998,Synthesis of dna-peptide conjugates from modeling chromiumiii-dna adducts,Biosis copyright: biol abs. rrm meeting abstract dna-peptide conjugates synthesis chromiumiii-dna adducts hexavalent chromium carcinogen genotoxin mutagen toxicology molecular genetics,Synthesis of dna-peptide conjugates from modeling chromiumiii-dna adducts Abs: Biosis copyright: biol abs. rrm meeting abstract dna-peptide conjugates synthesis chromiumiii-dna adducts hexavalent chromium carcinogen genotoxin mutagen toxicology molecular genetics
1290370,Bagchi et al. 1998,Chromium- and cadmium-induced oxidative stress and apoptosis in cultured J774A.1 macrophage cells,"BIOSIS COPYRIGHT: BIOL ABS. Sodium dichromate (Cr(VI)) and cadmium chloride (Cd(II)) are known to induce cytotoxicity and mutagenesis. in this study the toxic and apoptopic potentials of these cations on cultured J774A.1 macrophage cells were incubated with 0-0.60 muM concentrations of these cations for 0, 24, or 48 h at 37ê C. Changes in cell morphology were detected using phase contrast microscopy. The overall intracellular oxidized states of cells were measured at an excitation wavelength of 513 nm by laser scanning confocal microscopy using 2,7-dichlorofluorescein diacetate (DCFD) as the fluorescent probe. Signals were quantitated by integrating fluorescence over a user-defined area cell number. Concentration-dependent increases in fluorescence intensities were observed following treatment with Cr(VI) and Cd(II) ions with a 10-fold increase being produced by 0.40 muM Cr(VI). Fragmentation of nuclear DNA is a biochemical hallmark of programmed cell death (apoptosis). Concentration- and time-de","Chromium- and cadmium-induced oxidative stress and apoptosis in cultured J774A.1 macrophage cells Abs: BIOSIS COPYRIGHT: BIOL ABS. Sodium dichromate (Cr(VI)) and cadmium chloride (Cd(II)) are known to induce cytotoxicity and mutagenesis. in this study the toxic and apoptopic potentials of these cations on cultured J774A.1 macrophage cells were incubated with 0-0.60 muM concentrations of these cations for 0, 24, or 48 h at 37ê C. Changes in cell morphology were detected using phase contrast microscopy. The overall intracellular oxidized states of cells were measured at an excitation wavelength of 513 nm by laser scanning confocal microscopy using 2,7-dichlorofluorescein diacetate (DCFD) as the fluorescent probe. Signals were quantitated by integrating fluorescence over a user-defined area cell number. Concentration-dependent increases in fluorescence intensities were observed following treatment with Cr(VI) and Cd(II) ions with a 10-fold increase being produced by 0.40 muM Cr(VI). Fragmentation of nuclear DNA is a biochemical hallmark of programmed cell death (apoptosis). Concentration- and time-de"
1290369,Bose et al. 1998,Mechanisms of DNA damage by chromium(V) carcinogens,"Reactions of bis(2-ethyl-2-hydroxy-butanato)oxochromate(V) with pUC19 DNA, single-stranded calf thymus DNA (ss-ctDNA), a synthetic oligonucleotide, 5-GATCTATGGACTTACTTCAAGGCCGGGTAATGCTA-3'(35mer), deoxyguanosine and guanine were carried out in Bis-Tris buffer at pH 7.0. The plasmid DNA was only nicked, whereas the single-stranded DNA suffered extensive damage due to oxidation of the ribose moiety. The primary oxidation product was characterized as 5-methylene-2-furanone. Although all four bases (A, C, G and T) were released during the oxidation process, the concentration of guanine exceeds the other three. Orthophosphate and 3'-phosphates were also detected in this reaction. Likewise, the synthetic oligomer exhibits cleavage at all bases with a higher frequecncy at G sites. This increased cleavage at G sites was more apparent after treating the primary oxidation products with piperidine, which may indicate base oxidation as well. DNA oxidation is shown to proceed throug","Mechanisms of DNA damage by chromium(V) carcinogens Abs: Reactions of bis(2-ethyl-2-hydroxy-butanato)oxochromate(V) with pUC19 DNA, single-stranded calf thymus DNA (ss-ctDNA), a synthetic oligonucleotide, 5-GATCTATGGACTTACTTCAAGGCCGGGTAATGCTA-3'(35mer), deoxyguanosine and guanine were carried out in Bis-Tris buffer at pH 7.0. The plasmid DNA was only nicked, whereas the single-stranded DNA suffered extensive damage due to oxidation of the ribose moiety. The primary oxidation product was characterized as 5-methylene-2-furanone. Although all four bases (A, C, G and T) were released during the oxidation process, the concentration of guanine exceeds the other three. Orthophosphate and 3'-phosphates were also detected in this reaction. Likewise, the synthetic oligomer exhibits cleavage at all bases with a higher frequecncy at G sites. This increased cleavage at G sites was more apparent after treating the primary oxidation products with piperidine, which may indicate base oxidation as well. DNA oxidation is shown to proceed throug"
1290368,Dudek et al. 1998,Chromiumvi induces specific types of mitochondrial dna damage in human lung a549 cells,Biosis copyright: biol abs. rrm meeting abstract a549 cell line human lung cells mitochondrial dna damage carcinogenicity toxicology respiratory system chromiumvi induced,Chromiumvi induces specific types of mitochondrial dna damage in human lung a549 cells Abs: Biosis copyright: biol abs. rrm meeting abstract a549 cell line human lung cells mitochondrial dna damage carcinogenicity toxicology respiratory system chromiumvi induced
1290367,Ning et al. 1998,Studies on the cytotoxicity of chromium in osteoblasts,,Studies on the cytotoxicity of chromium in osteoblasts Abs: 
1290363,Dulout and  Seoane 1996,Aneugenic effect of cadmium nickel and hexavalent chromium using the anaphase-telophase test in chinese hamster ovary cells,Biosis copyright: biol abs. rrm meeting abstract in-vitro cytotoxicity chromosomal alterations mutation analysis,Aneugenic effect of cadmium nickel and hexavalent chromium using the anaphase-telophase test in chinese hamster ovary cells Abs: Biosis copyright: biol abs. rrm meeting abstract in-vitro cytotoxicity chromosomal alterations mutation analysis
1290361,Dudek and  Wetterhahn 1996,Carcinogenic chromium vi induces both cytosolic and mitochondrial oxidant stress in cultured human lung a549 cells,Biosis copyright: biol abs. rrm meeting abstract glutathione free radical reactive oxygen species cytotoxicity carcinogenesis,Carcinogenic chromium vi induces both cytosolic and mitochondrial oxidant stress in cultured human lung a549 cells Abs: Biosis copyright: biol abs. rrm meeting abstract glutathione free radical reactive oxygen species cytotoxicity carcinogenesis
1290359,Mizuno et al. 1995,Effects of hexavalent chromium on lipid peroxidation and hydroxyl radical generation in mouse kidney,Biosis copyright: biol abs. rrm meeting abstract heavy metal toxicity carcinogen free radical scavengers nephrotoxicity,Effects of hexavalent chromium on lipid peroxidation and hydroxyl radical generation in mouse kidney Abs: Biosis copyright: biol abs. rrm meeting abstract heavy metal toxicity carcinogen free radical scavengers nephrotoxicity
1290357,Wetterhahn et al. 1995,The role of metallothionein in chromium(VI) genotoxicity,"The effect of metallothionein (MT) on the genotoxicity of carcinogenic chromium(VI) has been determined using parental K1-2 and MMC-1. Chinese hamster ovary cells and their hMTII-transfected lines, K1-2 MT, MMC-1 MTa and MMC-1 MTb. The MT-overexpressing transfectant cell lines were consistently more sensitive to chromium(VI) cytotoxicity as measured by a colony-forming assay. However, less chromium{VI)-induced DNA damage, including DNA strand breaks, DNA-protein cross-links and chromium binding to DNA, was observed in the K1-2 MT-overexpressing transfectant cells compared to the K1-2 parental cells. Overexpression of MT in the K1-2 MT cells also resulted in lower levels of reactive oxygen species generated by chromium(VI) treatment compared with parental K1-2 cells as detected by the 2',7'-dichlorofluorescein assay. These studies indicate that metallothionein may play an important role in modulating both direct chromium-mediated and indirect ROS-mediated DNA damage produced by chromium(VI) treatment in vivo.","The role of metallothionein in chromium(VI) genotoxicity Abs: The effect of metallothionein (MT) on the genotoxicity of carcinogenic chromium(VI) has been determined using parental K1-2 and MMC-1. Chinese hamster ovary cells and their hMTII-transfected lines, K1-2 MT, MMC-1 MTa and MMC-1 MTb. The MT-overexpressing transfectant cell lines were consistently more sensitive to chromium(VI) cytotoxicity as measured by a colony-forming assay. However, less chromium{VI)-induced DNA damage, including DNA strand breaks, DNA-protein cross-links and chromium binding to DNA, was observed in the K1-2 MT-overexpressing transfectant cells compared to the K1-2 parental cells. Overexpression of MT in the K1-2 MT cells also resulted in lower levels of reactive oxygen species generated by chromium(VI) treatment compared with parental K1-2 cells as detected by the 2',7'-dichlorofluorescein assay. These studies indicate that metallothionein may play an important role in modulating both direct chromium-mediated and indirect ROS-mediated DNA damage produced by chromium(VI) treatment in vivo."
1290353,Burleson et al. 1994,Cytokine induction in human epidermal keratinocytes exposed to contact irritants and its relation to chemical-induced inflammation in mouse skin. AU - WILMER JL,"BIOSIS COPYRIGHT: BIOL ABS. In response to exogenous stimuli such as phorbol-12-myristate 13-acetate, ultraviolet B radiation, and lipopolysaccharide, human keratinocytes produce soluble mediators that are important in primary contact irritancy including cytokines that are associated with proinflammatory properties (interleukin-1alpha (IL-1alpha), tumor necrosis factor alpha), chemotaxis (IL-8), and growth activation (granulocyte/macrophage colony stimulating factor, IL-6, transforming growth factor alpha). We examined qua and quantitative changes in selected intracellular and secreted cytokines in human keratinocyte cultures in response to non-sensitizing contact irritants (croton oil, sodium lauryl sulfate, methyl salicylate, ethyl phenylpropiolate), sensitizing irritants (oxazolone, dinitrofluorobenzene), and ulcerative agents (phenol, benzalkonium chloride, chromium trioxide). The chemicals were also applied to mouse skin to assess whether the chemical-specific pattern of inflammation correlate","Cytokine induction in human epidermal keratinocytes exposed to contact irritants and its relation to chemical-induced inflammation in mouse skin. AU - WILMER JL Abs: BIOSIS COPYRIGHT: BIOL ABS. In response to exogenous stimuli such as phorbol-12-myristate 13-acetate, ultraviolet B radiation, and lipopolysaccharide, human keratinocytes produce soluble mediators that are important in primary contact irritancy including cytokines that are associated with proinflammatory properties (interleukin-1alpha (IL-1alpha), tumor necrosis factor alpha), chemotaxis (IL-8), and growth activation (granulocyte/macrophage colony stimulating factor, IL-6, transforming growth factor alpha). We examined qua and quantitative changes in selected intracellular and secreted cytokines in human keratinocyte cultures in response to non-sensitizing contact irritants (croton oil, sodium lauryl sulfate, methyl salicylate, ethyl phenylpropiolate), sensitizing irritants (oxazolone, dinitrofluorobenzene), and ulcerative agents (phenol, benzalkonium chloride, chromium trioxide). The chemicals were also applied to mouse skin to assess whether the chemical-specific pattern of inflammation correlate"
1290352,Alcedo et al. 1994,The genotoxic carcinogen chromium (VI) alters the metal-inducible expression but not the basal expression of the metallothionein gene in vivo,"The ability of the carcinogen chromium(VI) to affect the basal and zinc-inducible expression of liver metallothionein was examined in 14- and 18-day chicken embryos in vivo. Metallothionein expression varied with the stage of embryo development, with basal steady-state mRNA levels being approximately three times lower in livers of 18-day versus 14-day chicken embryos. Chromium(VI) treatment had no effect on the basal steady-state levels of metallothionein mRNA and protein in either 14- or 18-day chicken embryo liver. Treatment of 14-day embryos with zinc(II) resulted in a 3- to 5-fold increase in steady-state levels of metallothionein mRNA in liver. Pretreatment of 14-day embryos with chromium(VI) inhibited the zinc(II)-induced increase in steady-state levels of metallothionein mRNA and protein in liver by 30-50%. In contrast, chromium(VI) and/or zinc(II) treatments had no effect on steady-state levels of beta-actin mRNA.","The genotoxic carcinogen chromium (VI) alters the metal-inducible expression but not the basal expression of the metallothionein gene in vivo Abs: The ability of the carcinogen chromium(VI) to affect the basal and zinc-inducible expression of liver metallothionein was examined in 14- and 18-day chicken embryos in vivo. Metallothionein expression varied with the stage of embryo development, with basal steady-state mRNA levels being approximately three times lower in livers of 18-day versus 14-day chicken embryos. Chromium(VI) treatment had no effect on the basal steady-state levels of metallothionein mRNA and protein in either 14- or 18-day chicken embryo liver. Treatment of 14-day embryos with zinc(II) resulted in a 3- to 5-fold increase in steady-state levels of metallothionein mRNA in liver. Pretreatment of 14-day embryos with chromium(VI) inhibited the zinc(II)-induced increase in steady-state levels of metallothionein mRNA and protein in liver by 30-50%. In contrast, chromium(VI) and/or zinc(II) treatments had no effect on steady-state levels of beta-actin mRNA."
1290349,Wetterhahn et al. 1993,The role of ascorbate in metabolism and genotoxicity of chromium (VI),,The role of ascorbate in metabolism and genotoxicity of chromium (VI) Abs: 
1290348,Xu et al. 1993,Differential formation of chromium VI-induced DNA adducts and DNA-protein crosslinks in functionally distinct chromatin subfractions,Biosis copyright: biol abs. rrm abstract chinese hamster ovary cell toxicodynamics nuclear matrix fraction environmental toxin,Differential formation of chromium VI-induced DNA adducts and DNA-protein crosslinks in functionally distinct chromatin subfractions Abs: Biosis copyright: biol abs. rrm abstract chinese hamster ovary cell toxicodynamics nuclear matrix fraction environmental toxin
1290347,Mccaffrey and  Hamilton 1993,The carcinogenic dna crosslinking agent chromium-vi alters hormonal regulation of phosphoenolpyruvate carboxykinase gene expression in-vivo,Biosis copyright: biol abs. rrm abstract chicken,The carcinogenic dna crosslinking agent chromium-vi alters hormonal regulation of phosphoenolpyruvate carboxykinase gene expression in-vivo Abs: Biosis copyright: biol abs. rrm abstract chicken
1290346,Becher et al. 1992,Differential metabolic activation of carcinogens induction of dna damage and expression of p450 enzymes in different types of lung cells,Biosis copyright: biol abs. rrm abstract rat rabbit benzaceanthrylene chromium-vi clara cell alveolar type ii cell lung macrophage gene expression lung carcinogenesis,Differential metabolic activation of carcinogens induction of dna damage and expression of p450 enzymes in different types of lung cells Abs: Biosis copyright: biol abs. rrm abstract rat rabbit benzaceanthrylene chromium-vi clara cell alveolar type ii cell lung macrophage gene expression lung carcinogenesis
1290345,Wetterhahn et al. 1992,Chromium-vi-induced dna damage differentially affects gene expression,Biosis copyright: biol abs. rrm abstract chick,Chromium-vi-induced dna damage differentially affects gene expression Abs: Biosis copyright: biol abs. rrm abstract chick
1290344,Gartland et al. 1991,Computer pattern recognition analysis of PMR spectroscopic data from urine obtained from rats in various nephrotoxicity states,BIOSIS COPYRIGHT: BIOL ABS. RRM PROTON NMR DRUG METABOLISM TOXICITY STATE XENOBIOTIC COMPOUND,Computer pattern recognition analysis of PMR spectroscopic data from urine obtained from rats in various nephrotoxicity states Abs: BIOSIS COPYRIGHT: BIOL ABS. RRM PROTON NMR DRUG METABOLISM TOXICITY STATE XENOBIOTIC COMPOUND
1290342,Sidhu et al. 1990,Induction of morphological transformation anchorage-independent growth and plasminogen activators in non-tumorigenic hos cells by chromium-vi salts,Biosis copyright: biol abs. rrm abstract human osteosarcoma cells carcinogen urokinase,Induction of morphological transformation anchorage-independent growth and plasminogen activators in non-tumorigenic hos cells by chromium-vi salts Abs: Biosis copyright: biol abs. rrm abstract human osteosarcoma cells carcinogen urokinase
1290341,Sehlmeyer and  Beyersmann 1990,Influence of chromium-vi on the uv-induced dna repair in cultured human cells,Biosis copyright: biol abs. rrm abstract repair enzymes dna synthesis,Influence of chromium-vi on the uv-induced dna repair in cultured human cells Abs: Biosis copyright: biol abs. rrm abstract repair enzymes dna synthesis
1290340,O'Brien and  Wang 1989,Coordination chemistry and the carcinogenicity and mutagenicity of chromium(VI),"Chromate is a known carcinogen, it is only in recent years that the molecular mechanisms by which this toxicity may be expressed have been investigated. The toxicity of chromate may be mediated by the reaction of chromium(VI) with glutathione (GSH) to generate relatively stable chromium(V) complexes and other more reactive intermediates. The conditions favouring the formation of such complexes have been studied. Reactive intermediates generated during the reduction of chromate by GSH include thionyl radicals and at least two relatively stable chromium(V) species (g -1.996 and g -.986). Mixtures of chromium(VI) and glutathione and a chromium(V) complex of glutathione, which we have isolated from the reaction (g = 1.996), are capable of causing strand breaks in bacteriophage PM2 DNA. In contrast a chromium(III) complex of GSSG, one of the final products of the reaction between GSH and chromium(VI), does not damage DNA in closed circle assays. These observations support the suggestion that reactive intermediates generated during the reduction of chromium(VI) provide one route by which the genotoxicity of chromate may be expressed.","Coordination chemistry and the carcinogenicity and mutagenicity of chromium(VI) Abs: Chromate is a known carcinogen, it is only in recent years that the molecular mechanisms by which this toxicity may be expressed have been investigated. The toxicity of chromate may be mediated by the reaction of chromium(VI) with glutathione (GSH) to generate relatively stable chromium(V) complexes and other more reactive intermediates. The conditions favouring the formation of such complexes have been studied. Reactive intermediates generated during the reduction of chromate by GSH include thionyl radicals and at least two relatively stable chromium(V) species (g -1.996 and g -.986). Mixtures of chromium(VI) and glutathione and a chromium(V) complex of glutathione, which we have isolated from the reaction (g = 1.996), are capable of causing strand breaks in bacteriophage PM2 DNA. In contrast a chromium(III) complex of GSSG, one of the final products of the reaction between GSH and chromium(VI), does not damage DNA in closed circle assays. These observations support the suggestion that reactive intermediates generated during the reduction of chromium(VI) provide one route by which the genotoxicity of chromate may be expressed."
1290339,Miller et al. 1990,The detection of DNA-protein complexes in vitro by an immunological assay. AU - COSMA GN,"BIOSIS COPYRIGHT: BIOL ABS. We have developed an immunological assay to detect DNA-protein complexes (DPCs) in cell cultures treated with environmental toxicants. The assay uses an antiserum developed against K2CrO4-induced DPCs, which recognizes an acidic protein with a molecular weight of 94 kDaltons. The method uses a filter-binding assay to trap the DPCs from SDS-lysed cell cultures on polycarbonate filters, after which they are immunologically probed with the DPC antiserum. Cultures of Chinese hamster ovary cells were treated with K2CrO4, formaldehyde or UV irradiation. DPCs were detected immunologically in cells treated with K2CrO4 or UV irradiation, but not in those treated with formaldehyde. These results were similar to those obtained when DPCs were detected by filter-binding assay using radiolabelled cell cultures to measure the adherence of protein and DNA to the filters. In addition, both methods have analogous dose responses of DPC formation in K2CrO4-treated cells. This novel immunol","The detection of DNA-protein complexes in vitro by an immunological assay. AU - COSMA GN Abs: BIOSIS COPYRIGHT: BIOL ABS. We have developed an immunological assay to detect DNA-protein complexes (DPCs) in cell cultures treated with environmental toxicants. The assay uses an antiserum developed against K2CrO4-induced DPCs, which recognizes an acidic protein with a molecular weight of 94 kDaltons. The method uses a filter-binding assay to trap the DPCs from SDS-lysed cell cultures on polycarbonate filters, after which they are immunologically probed with the DPC antiserum. Cultures of Chinese hamster ovary cells were treated with K2CrO4, formaldehyde or UV irradiation. DPCs were detected immunologically in cells treated with K2CrO4 or UV irradiation, but not in those treated with formaldehyde. These results were similar to those obtained when DPCs were detected by filter-binding assay using radiolabelled cell cultures to measure the adherence of protein and DNA to the filters. In addition, both methods have analogous dose responses of DPC formation in K2CrO4-treated cells. This novel immunol"
1290338,Standeven and  Wetterhahn 1989,Chromium-vi toxicity uptake reduction and dna damage,Biosis copyright: biol abs. rrm review vertebrate chromium iv chromium iii carcinogenicity,Chromium-vi toxicity uptake reduction and dna damage Abs: Biosis copyright: biol abs. rrm review vertebrate chromium iv chromium iii carcinogenicity
1290330,Nijs and  Kirsch-Volders 1986,"Induction of spindle inhibition and abnormal mitotic figures by Cr(II), Cr(III) and Cr(VI) ions","A differential staining technique for chromosomes and spindles was used to compare the effects of chromium compounds of different oxidation states with either no, or very low (Cr(II) and Cr(III) or high (Cr(VI) carcinogenic properties. Neither CrCl2, nor CrCl3 (except at 10(-4) M) had any effect on spindle formation and/or chromosome segregation after exposure up to 10(-7) and 10(-5) M, respectively. None of them significantly influenced the mitotic index. In contrast, the Cr(VI) products (Na2CrO4 and CaCrO4) induced a dose-dependent increase of aberrant division patterns up to 10(-4) and 10(-5) M, respectively. Moreover, with CaCrO4, a high frequency of cells with dislocated metaphase chromosomes or malformed spindles with clustered chromosomes were observed. Since these cell types are potential sources of aneuploid daughter cells, they represent a potential risk for cancer induction. These experiments clearly demonstrate that the differential staining methods allows discrimination between spindle modifiers which induce lethal toxicity and those which may lead to possible tumour induction.","Induction of spindle inhibition and abnormal mitotic figures by Cr(II), Cr(III) and Cr(VI) ions Abs: A differential staining technique for chromosomes and spindles was used to compare the effects of chromium compounds of different oxidation states with either no, or very low (Cr(II) and Cr(III) or high (Cr(VI) carcinogenic properties. Neither CrCl2, nor CrCl3 (except at 10(-4) M) had any effect on spindle formation and/or chromosome segregation after exposure up to 10(-7) and 10(-5) M, respectively. None of them significantly influenced the mitotic index. In contrast, the Cr(VI) products (Na2CrO4 and CaCrO4) induced a dose-dependent increase of aberrant division patterns up to 10(-4) and 10(-5) M, respectively. Moreover, with CaCrO4, a high frequency of cells with dislocated metaphase chromosomes or malformed spindles with clustered chromosomes were observed. Since these cell types are potential sources of aneuploid daughter cells, they represent a potential risk for cancer induction. These experiments clearly demonstrate that the differential staining methods allows discrimination between spindle modifiers which induce lethal toxicity and those which may lead to possible tumour induction."
1290328,Wiegand and  Bolt 1985,Intracellular disposition of chromium-vi in the isolated perfused rat liver,Biosis copyright: biol abs. rrm abstract,Intracellular disposition of chromium-vi in the isolated perfused rat liver Abs: Biosis copyright: biol abs. rrm abstract
1290325,Grant 1999,Chromium VI toxicity in osteoblasts: Involvement of glutathione reductase. AU - NING J,Biosis copyright: biol abs. rrm chromium vi toxicity in osteoblasts: involvement of glutathione reductaseymeeting abstract meeting poster rat enzymology toxicology cell biology osteoblasts cytotoxicity chromium vi toxic effects cellular toxicity enzymes glutathione reductase skeletal system,Chromium VI toxicity in osteoblasts: Involvement of glutathione reductase. AU - NING J Abs: Biosis copyright: biol abs. rrm chromium vi toxicity in osteoblasts: involvement of glutathione reductaseymeeting abstract meeting poster rat enzymology toxicology cell biology osteoblasts cytotoxicity chromium vi toxic effects cellular toxicity enzymes glutathione reductase skeletal system
1290324,Rodriguez et al. 2008,"Evaluation of Worker Exposures to Noise, Metalworking Fluids, Welding Fumes, and Acids During Metal Conduit Manufacturing. Heath Hazard Evaluation Report: HETA-2006-0332-3058, Republic Conduit, Louisville, Kentucky, April 2008","On August 8, 2006, NIOSH received a confidential employee request for an HHE at Republic Conduit in Louisville, Kentucky. The requestors expressed concerns about workplace exposures to acids, unsafe confined space entry procedures, and inadequate PPE for handling acids. We conducted an initial site visit to Republic Conduit on November 13, 2006, during which we performed a walk-through of the facility and interviewed workers. Based on our observations, workers were potentially exposed to acids, Cr(VI), MWFs, welding fumes, and noise. Of the 13 employees who we selected for medical interviews, two reported acute upper respiratory symptoms and exacerbation of asthma symptoms related to a brief exposure to HCL during a leak. Four reported injuries not associated with acid exposure, which included back pain, skin irritation, lacerations, and crushed fingers. A review of OSHAs Form 300 Log of Work-Related Injuries and Illnesses for 2006 revealed that of 21 entries, 11 listed crushed fingers or lacerations caused by contact with conduit. We conducted a follow-up site visit to Republic Conduit during March 5-8, 2007, to sample for acid mists, MWFs, elements from welding fumes, and Cr(VI) from chromic acid; conduct noise dosimetry; and review the companys written health and safety programs. All sampling results were below applicable OELs except for noise and MWFs. Of the 35 personal noise exposure measurements taken during this evaluation, 33 exceeded the NIOSH REL of 85 dBA. Because OSHA uses different criteria to measure noise exposure, only six exceeded the OSHA PEL of 90 dBA, though 29 exceeded the OSHA AL of 85 dBA. Three of 21 PBZ sample results equaled or exceeded the NIOSH REL-TWA for MWFs of 0.4 mg/m3 (thoracic particulate mass).","Evaluation of Worker Exposures to Noise, Metalworking Fluids, Welding Fumes, and Acids During Metal Conduit Manufacturing. Heath Hazard Evaluation Report: HETA-2006-0332-3058, Republic Conduit, Louisville, Kentucky, April 2008 Abs: On August 8, 2006, NIOSH received a confidential employee request for an HHE at Republic Conduit in Louisville, Kentucky. The requestors expressed concerns about workplace exposures to acids, unsafe confined space entry procedures, and inadequate PPE for handling acids. We conducted an initial site visit to Republic Conduit on November 13, 2006, during which we performed a walk-through of the facility and interviewed workers. Based on our observations, workers were potentially exposed to acids, Cr(VI), MWFs, welding fumes, and noise. Of the 13 employees who we selected for medical interviews, two reported acute upper respiratory symptoms and exacerbation of asthma symptoms related to a brief exposure to HCL during a leak. Four reported injuries not associated with acid exposure, which included back pain, skin irritation, lacerations, and crushed fingers. A review of OSHAs Form 300 Log of Work-Related Injuries and Illnesses for 2006 revealed that of 21 entries, 11 listed crushed fingers or lacerations caused by contact with conduit. We conducted a follow-up site visit to Republic Conduit during March 5-8, 2007, to sample for acid mists, MWFs, elements from welding fumes, and Cr(VI) from chromic acid; conduct noise dosimetry; and review the companys written health and safety programs. All sampling results were below applicable OELs except for noise and MWFs. Of the 35 personal noise exposure measurements taken during this evaluation, 33 exceeded the NIOSH REL of 85 dBA. Because OSHA uses different criteria to measure noise exposure, only six exceeded the OSHA PEL of 90 dBA, though 29 exceeded the OSHA AL of 85 dBA. Three of 21 PBZ sample results equaled or exceeded the NIOSH REL-TWA for MWFs of 0.4 mg/m3 (thoracic particulate mass)."
1290319,Vermulen et al. 1997,Chromium Environmental Risk Assessment,"Interim rept. Apr 96-Oct 97. ew of chromium environmental criteria, supporting scientific studies and recent research activities was conducted to determine the implications of evolving observations on cancer risk to DoD environmental clean-up programs. Public concern over the occupational cancer risk of hexavalent chromium is influencing a new assessment of the risk data. Toxicology literature on the human health hazards, cancer and non-cancer, was reviewed. On-going epidemiology efforts were unavailable for a thorough assessment. Data gaps in the literature were noted as support for research recommendations- Alternatives to chromium speciation at environmental clean-up sites were recommended as an interim measure. An extensive bibliography is provided.","Chromium Environmental Risk Assessment Abs: Interim rept. Apr 96-Oct 97. ew of chromium environmental criteria, supporting scientific studies and recent research activities was conducted to determine the implications of evolving observations on cancer risk to DoD environmental clean-up programs. Public concern over the occupational cancer risk of hexavalent chromium is influencing a new assessment of the risk data. Toxicology literature on the human health hazards, cancer and non-cancer, was reviewed. On-going epidemiology efforts were unavailable for a thorough assessment. Data gaps in the literature were noted as support for research recommendations- Alternatives to chromium speciation at environmental clean-up sites were recommended as an interim measure. An extensive bibliography is provided."
1290317,May et al. 1997,Occupational Risk from Chromium,"Final rept. Oct 96-Jul 97. avy (Navy) operations require the use of chrome (Cr) compounds in its various defense program activities. However, certain forms of Cr have been shown to cause acute and chronic toxicity. A reduction in the OSHA PEL from 0.5 mg/m3 to 0.0005 mg/m3 has been proposed. Accordingly, the Navy and the Department of Defense (DoD) are concerned over the potential for any adverse affect occurring among the exposed personnel. Currently available chrome toxicity information were reviewed and assessed in this report. Existing epidemiological data and pharmacokinetic models suggest that cancer potency may vary with solubility and form of hexavalent chrome. A new analytical method, ID 215, is now available that identifies hexavalent Cr at the proposed levels. Personal samples analyzed using this method were obtained from the Navy Occupational Exposure Database and evaluated. Estimated potential risk to Naval personnel from hexavalent chrome exposure, assuming no personal protective equipment, were in the 1/10000 range for the majority of the processes monitored. The highest risks calculated were in the 1/100 to 1/1000 range for abrasive blasting using mineral spirits and sand. Several operations, however, would require the use of respiratory protection and, therefore, risk would be expected to be appreciably less. In general, exposure levels analyzed using ID-2l5 method were generally one order of magnitude below current standards.","Occupational Risk from Chromium Abs: Final rept. Oct 96-Jul 97. avy (Navy) operations require the use of chrome (Cr) compounds in its various defense program activities. However, certain forms of Cr have been shown to cause acute and chronic toxicity. A reduction in the OSHA PEL from 0.5 mg/m3 to 0.0005 mg/m3 has been proposed. Accordingly, the Navy and the Department of Defense (DoD) are concerned over the potential for any adverse affect occurring among the exposed personnel. Currently available chrome toxicity information were reviewed and assessed in this report. Existing epidemiological data and pharmacokinetic models suggest that cancer potency may vary with solubility and form of hexavalent chrome. A new analytical method, ID 215, is now available that identifies hexavalent Cr at the proposed levels. Personal samples analyzed using this method were obtained from the Navy Occupational Exposure Database and evaluated. Estimated potential risk to Naval personnel from hexavalent chrome exposure, assuming no personal protective equipment, were in the 1/10000 range for the majority of the processes monitored. The highest risks calculated were in the 1/100 to 1/1000 range for abrasive blasting using mineral spirits and sand. Several operations, however, would require the use of respiratory protection and, therefore, risk would be expected to be appreciably less. In general, exposure levels analyzed using ID-2l5 method were generally one order of magnitude below current standards."
1290315,Young et al. 1994,Effect of metals on the development of hyperactivated motility by rabbit sperm cells,"Final rept. Feb-Sep 92. sperm acquire motion patterns mimicking hyperactivated motility upon incubation in medium M. Lead and cadmium, at concentrations present in seminal plasma of men exposed to the metals, prevented development of these motion patterns in a concentration dependent manner. Nonhyperactivated motility was unaffected. Zinc and mercury, at concentrations that did not inhibit motility, decreased the percentage of sperm with motions that mimicked hyperactivated motility over time, but the decrease was independent of concentration. Concentrations of hexavalent chromium twice that found in seminal plasma of exposed men had no significant effect, as a function of time and concentration, on the percent of sperm with motility mimicking hyperactivated motility. As lead and cadmium are reproductive toxicants, the inhibition of motions that mimic hyperactivated motility in medium M may be useful for the identification of metals and other compounds with the potential to adversely affect reproduction.","Effect of metals on the development of hyperactivated motility by rabbit sperm cells Abs: Final rept. Feb-Sep 92. sperm acquire motion patterns mimicking hyperactivated motility upon incubation in medium M. Lead and cadmium, at concentrations present in seminal plasma of men exposed to the metals, prevented development of these motion patterns in a concentration dependent manner. Nonhyperactivated motility was unaffected. Zinc and mercury, at concentrations that did not inhibit motility, decreased the percentage of sperm with motions that mimicked hyperactivated motility over time, but the decrease was independent of concentration. Concentrations of hexavalent chromium twice that found in seminal plasma of exposed men had no significant effect, as a function of time and concentration, on the percent of sperm with motility mimicking hyperactivated motility. As lead and cadmium are reproductive toxicants, the inhibition of motions that mimic hyperactivated motility in medium M may be useful for the identification of metals and other compounds with the potential to adversely affect reproduction."
1290314,O'Flaherty and  Radike 1991,Pharmacokinetic modeling of trivalent and hexavalent chromium based on ingestion and inhalation of soluble chromium compounds,"Final report for period June 1990 through December 1991. A physiologically-based model of chromium disposition in the rat has been developed. Absorption, distribution, and excretion of chromium are superimposed on a general physiological model of rat growth and development. The model considers both Cr (VI) and Cr (III), administered either orally or by inhalation. It incorporates reduction of Cr (VI) to Cr (III) in all tissues including the lung and the GI tract. Chromium is cleared from the lung by systemic absorption and by mucociliary clearance into the GI tract. Parameter values are based on literature data and on the results of a concurrent experimental study in which rats were given either Cr (111) or Cr (VI) either in the drinking water or by inhalation. Blood, tissue, urine, and fecal chromium levels were monitored on days 2, 5, 10, 20, and 40 of the 40-day exposure period, and at 20 days postexposure. Cr(VI), Cr(III), Oral exposure, Inhalation exposure, Physiologically-based model.","Pharmacokinetic modeling of trivalent and hexavalent chromium based on ingestion and inhalation of soluble chromium compounds Abs: Final report for period June 1990 through December 1991. A physiologically-based model of chromium disposition in the rat has been developed. Absorption, distribution, and excretion of chromium are superimposed on a general physiological model of rat growth and development. The model considers both Cr (VI) and Cr (III), administered either orally or by inhalation. It incorporates reduction of Cr (VI) to Cr (III) in all tissues including the lung and the GI tract. Chromium is cleared from the lung by systemic absorption and by mucociliary clearance into the GI tract. Parameter values are based on literature data and on the results of a concurrent experimental study in which rats were given either Cr (111) or Cr (VI) either in the drinking water or by inhalation. Blood, tissue, urine, and fecal chromium levels were monitored on days 2, 5, 10, 20, and 40 of the 40-day exposure period, and at 20 days postexposure. Cr(VI), Cr(III), Oral exposure, Inhalation exposure, Physiologically-based model."
1290297,Bano et al. 2012,Chromium (VI) induced oxidative stress in Hapalosiphon fontinalis,"Heavy metals in air, soil, and water are great threat to the environment. Effluents from paint, tannery, electroplating industries contaminate irrigation water, which in turn exhibit toxic response to many crops and microorganisms including cyanobacterial biofertilizers. In aquatic system Cr exist in many forms, whereas, Cr(VI) is most toxic. In the present study metabolic alteration were studied in a cyanobacterial biofertilizer (Hapalosiphon fontinalis) in response to chromium (VI) with special reference to oxidative stress. Maximum growth inhibition was observed at 0.5 mM Cr at 20th day. Lipid peroxidation as TBARS increased with the increase in chromium concentration and suggested free radical mediated toxicity. Elevated levels of ?- carotene, astaxanthin, superoxide dismutase, catalase and ascorbate peroxidase indicated their role in survival strategy of the test organism.","Chromium (VI) induced oxidative stress in Hapalosiphon fontinalis Abs: Heavy metals in air, soil, and water are great threat to the environment. Effluents from paint, tannery, electroplating industries contaminate irrigation water, which in turn exhibit toxic response to many crops and microorganisms including cyanobacterial biofertilizers. In aquatic system Cr exist in many forms, whereas, Cr(VI) is most toxic. In the present study metabolic alteration were studied in a cyanobacterial biofertilizer (Hapalosiphon fontinalis) in response to chromium (VI) with special reference to oxidative stress. Maximum growth inhibition was observed at 0.5 mM Cr at 20th day. Lipid peroxidation as TBARS increased with the increase in chromium concentration and suggested free radical mediated toxicity. Elevated levels of ?- carotene, astaxanthin, superoxide dismutase, catalase and ascorbate peroxidase indicated their role in survival strategy of the test organism."
1290296,Arakawa et al. ,Chromium (VI) induces both bulky DNA adducts and oxidative DNA damage at adenines and guanines in the p53 gene of human lung cells,"Chromium (VI) [Cr(VI)], a ubiquitous environmental carcinogen, is generally believed to induce mainly mutagenic binary and ternary Cr(III)-deoxyguanosine (dG)-DNA adducts in human cells. However, both adenine (A) and guanine (G) mutations are found in the p53 gene in Cr exposure-related lung cancer. Using UvrABC nuclease and formamidopyrimidine glycosylase (Fpg), and ligation-mediated PCR methods, we mapped the distribution of bulky DNA adducts (BDA) and oxidative DNA damage (ODD) in the p53 gene in Cr(VI)-treated human lung cells. We found that both BDA and ODD formed at 2'-deoxyadenosine (dA) and dG bases. To understand the causes for these Cr-induced DNA damages, we mapped the distribution of BDA adducts and ODD in the p53 gene DNA fragments induced by Cr(III), Cr(VI) and Cr(V), the three major cellular Cr forms. We found that (i) dA at -CA- is a major Cr(VI) binding site followed by -GG- and -G-. Cr(VI) does not bind to -GGG-, (ii) Cr(VI)-DNA binding specificity is distinctly different from the Cr(III)-DNA binding in which -GGG- and -GG- are preferential sites, (iii) Cr(V) binding sites include all of Cr(VI) and Cr(III)-DNA binding sites and (iv) Cr(VI) and Cr(V) induce Fpg-sensitive sites at -G-. Together, these results suggest that Cr(VI) induction of BDA and ODD at dA and dG residues is through Cr(V) intermediate. We propose that these Cr(VI)-induced BDA and ODD contribute to mutagenesis of the p53 gene that leads to lung carcinogenesis.","Chromium (VI) induces both bulky DNA adducts and oxidative DNA damage at adenines and guanines in the p53 gene of human lung cells Abs: Chromium (VI) [Cr(VI)], a ubiquitous environmental carcinogen, is generally believed to induce mainly mutagenic binary and ternary Cr(III)-deoxyguanosine (dG)-DNA adducts in human cells. However, both adenine (A) and guanine (G) mutations are found in the p53 gene in Cr exposure-related lung cancer. Using UvrABC nuclease and formamidopyrimidine glycosylase (Fpg), and ligation-mediated PCR methods, we mapped the distribution of bulky DNA adducts (BDA) and oxidative DNA damage (ODD) in the p53 gene in Cr(VI)-treated human lung cells. We found that both BDA and ODD formed at 2'-deoxyadenosine (dA) and dG bases. To understand the causes for these Cr-induced DNA damages, we mapped the distribution of BDA adducts and ODD in the p53 gene DNA fragments induced by Cr(III), Cr(VI) and Cr(V), the three major cellular Cr forms. We found that (i) dA at -CA- is a major Cr(VI) binding site followed by -GG- and -G-. Cr(VI) does not bind to -GGG-, (ii) Cr(VI)-DNA binding specificity is distinctly different from the Cr(III)-DNA binding in which -GGG- and -GG- are preferential sites, (iii) Cr(V) binding sites include all of Cr(VI) and Cr(III)-DNA binding sites and (iv) Cr(VI) and Cr(V) induce Fpg-sensitive sites at -G-. Together, these results suggest that Cr(VI) induction of BDA and ODD at dA and dG residues is through Cr(V) intermediate. We propose that these Cr(VI)-induced BDA and ODD contribute to mutagenesis of the p53 gene that leads to lung carcinogenesis."
1290295,Xiao et al. 2012,Hexavalent chromium targets mitochondrial respiratory chain complex I to induce reactive oxygen species-dependent caspase-3 activation in L-02 hepatocytes,"Hexavalent chromium [Cr(VI)], which is used for various industrial applications, such as leather tanning and chroming, can cause a number of human diseases including inflammation and cancer. Cr(VI) exposure leads to severe damage to the liver, but the mechanisms involved in Cr(VI)-mediated toxicity in the liver are unclear. The present study provides evidence that Cr(VI) enhances reactive oxygen species (ROS) accumulation by inhibiting the mitochondrial respiratory chain complex (MRCC) I. Cr(VI) did not affect the expression levels of antioxidative proteins such as superoxide dismutase (SOD), catalase and thioredoxin (Trx), indicating that the antioxidative system was not involved in Cr(VI)-induced ROS accumulation. We found that ROS mediated caspase-3 activation partially depends on the downregulation of the heat shock protein (HSP) 70 and 90. In order to confirm our hypothesis that ROS plays a key role in Cr(VI)-mediated cytotoxicity, we used N-acetylcysteine (NAC) to inhibit the accumulation of ROS. NAC successfully blocked the inhibition of HSP70 and HSP90 as well as the activation of caspase-3, suggesting that ROS is essential in Cr(VI)-induced caspase-3 activation. By applying different MRCC substrates as electron donors, we also confirmed that Cr(VI) could accept the electrons leaked from MRCC I and the reduction occurs at MRCC I. In conclusion, the present study demonstrates that Cr(VI) induces ROS-dependent caspase-3 activation by inhibiting MRCC I activity, and MRCC I has been identified as a new target and a new mechanism for the apoptosis-inducing activity displayed by Cr(VI).","Hexavalent chromium targets mitochondrial respiratory chain complex I to induce reactive oxygen species-dependent caspase-3 activation in L-02 hepatocytes Abs: Hexavalent chromium [Cr(VI)], which is used for various industrial applications, such as leather tanning and chroming, can cause a number of human diseases including inflammation and cancer. Cr(VI) exposure leads to severe damage to the liver, but the mechanisms involved in Cr(VI)-mediated toxicity in the liver are unclear. The present study provides evidence that Cr(VI) enhances reactive oxygen species (ROS) accumulation by inhibiting the mitochondrial respiratory chain complex (MRCC) I. Cr(VI) did not affect the expression levels of antioxidative proteins such as superoxide dismutase (SOD), catalase and thioredoxin (Trx), indicating that the antioxidative system was not involved in Cr(VI)-induced ROS accumulation. We found that ROS mediated caspase-3 activation partially depends on the downregulation of the heat shock protein (HSP) 70 and 90. In order to confirm our hypothesis that ROS plays a key role in Cr(VI)-mediated cytotoxicity, we used N-acetylcysteine (NAC) to inhibit the accumulation of ROS. NAC successfully blocked the inhibition of HSP70 and HSP90 as well as the activation of caspase-3, suggesting that ROS is essential in Cr(VI)-induced caspase-3 activation. By applying different MRCC substrates as electron donors, we also confirmed that Cr(VI) could accept the electrons leaked from MRCC I and the reduction occurs at MRCC I. In conclusion, the present study demonstrates that Cr(VI) induces ROS-dependent caspase-3 activation by inhibiting MRCC I activity, and MRCC I has been identified as a new target and a new mechanism for the apoptosis-inducing activity displayed by Cr(VI)."
1290294,Thompson et al. 2012,Assessment of genotoxic potential of Cr(VI) in the mouse duodenum: An in silico comparison with mutagenic and nonmutagenic carcinogens across tissues,"In vitro studies on hexavalent chromium [Cr(VI)] indicate that reduced forms of this metal can interact with DNA and cause mutations. Recently, Cr(VI) was shown to induce intestinal tumors in mice; however, Cr(VI) elicited redox changes, cytotoxicity and hyperplasia - suggesting involvement of tissue injury rather than direct mutagenesis. Moreover, toxicogenomic analyses indicated limited evidence for DNA damage responses. Herein, we extend these toxicogenomic analyses by comparing the gene expression patterns elicited by Cr(VI) with those of four mutagenic and four nonmutagenic carcinogens. To date, toxicogenomic profiles for mutagenic and nonmutagenic duodenal carcinogens do not exist, thus duodenal gene changes in mice were compared to those elicited by hepatocarcinogens. Specifically, duodenal gene changes in mice following exposure to Cr(VI) in drinking water were compared to hepatic gene changes previously identified as potentially discriminating mutagenic and nonmutagenic hepatocarcinogens. Using multivariate statistical analyses (including logistic regression classification), the Cr(VI) gene responses clustered apart from mutagenic carcinogens and closely with nonmutagenic carcinogens. These findings are consistent with other intestinal data supporting a nonmutagenic mode of action (MOA). These findings may be useful as part of a full weight of evidence MOA evaluation for Cr(VI)-induced intestinal carcinogenesis. Limitations to this analysis will also be discussed.","Assessment of genotoxic potential of Cr(VI) in the mouse duodenum: An in silico comparison with mutagenic and nonmutagenic carcinogens across tissues Abs: In vitro studies on hexavalent chromium [Cr(VI)] indicate that reduced forms of this metal can interact with DNA and cause mutations. Recently, Cr(VI) was shown to induce intestinal tumors in mice; however, Cr(VI) elicited redox changes, cytotoxicity and hyperplasia - suggesting involvement of tissue injury rather than direct mutagenesis. Moreover, toxicogenomic analyses indicated limited evidence for DNA damage responses. Herein, we extend these toxicogenomic analyses by comparing the gene expression patterns elicited by Cr(VI) with those of four mutagenic and four nonmutagenic carcinogens. To date, toxicogenomic profiles for mutagenic and nonmutagenic duodenal carcinogens do not exist, thus duodenal gene changes in mice were compared to those elicited by hepatocarcinogens. Specifically, duodenal gene changes in mice following exposure to Cr(VI) in drinking water were compared to hepatic gene changes previously identified as potentially discriminating mutagenic and nonmutagenic hepatocarcinogens. Using multivariate statistical analyses (including logistic regression classification), the Cr(VI) gene responses clustered apart from mutagenic carcinogens and closely with nonmutagenic carcinogens. These findings are consistent with other intestinal data supporting a nonmutagenic mode of action (MOA). These findings may be useful as part of a full weight of evidence MOA evaluation for Cr(VI)-induced intestinal carcinogenesis. Limitations to this analysis will also be discussed."
1290293,Zhang et al. ,XRCC1 Arg399Gln was associated with repair capacity for DNA damage induced by occupational chromium exposure,"ABSTRACT: BACKGROUND: Occupational chromium exposure may induce DNA damage and lead to lung cancer and other work-related diseases. DNA repair gene polymorphisms, which may alter the efficiency of DNA repair, thus may contribute to genetic susceptibility of DNA damage. The aim of this study was to test the hypothesis that the genetic variations of 9 major DNA repair genes could modulate the hexavalent chromium (Cr (VI))-induced DNA damage. FINDINGS: The median (P25-P75) of Olive tail moment was 0.93 (0.58-1.79) for individuals carrying GG genotype of XRCC1 Arg399Gln (G/A), 0.73 (0.46-1.35) for GA heterozygote and 0.50 (0.43-0.93) for AA genotype. Significant difference was found among the subjects with three different genotypes (P = 0.048) after adjusting the confounding factors. The median of Olive tail moment of the subjects carrying A allele (the genotypes of AA and GA) was 0.66 (0.44-1.31), which was significantly lower than that of subjects with GG genotype (P = 0.043). The A allele conferred a significantly reduced risk of DNA damage with the OR of 0.39 (95% CI: 0.15-0.99, P = 0.048). No significant association was found between the XRCC1Arg194Trp, ERCC1 C8092A, ERCC5 His1104Asp, ERCC6 Gly399Asp, GSTP1 Ile105Val, OGG1 Ser326Cys, XPC Lys939Gln, XPD Lys751Gln and DNA damage. CONCLUSION: The polymorphism of Arg399Gln in XRCC1 was associated with the Cr (VI)- induced DNA damage. XRCC1 Arg399Gln may serve as a genetic biomarker of susceptibility for Cr (VI)- induced DNA damage.","XRCC1 Arg399Gln was associated with repair capacity for DNA damage induced by occupational chromium exposure Abs: ABSTRACT: BACKGROUND: Occupational chromium exposure may induce DNA damage and lead to lung cancer and other work-related diseases. DNA repair gene polymorphisms, which may alter the efficiency of DNA repair, thus may contribute to genetic susceptibility of DNA damage. The aim of this study was to test the hypothesis that the genetic variations of 9 major DNA repair genes could modulate the hexavalent chromium (Cr (VI))-induced DNA damage. FINDINGS: The median (P25-P75) of Olive tail moment was 0.93 (0.58-1.79) for individuals carrying GG genotype of XRCC1 Arg399Gln (G/A), 0.73 (0.46-1.35) for GA heterozygote and 0.50 (0.43-0.93) for AA genotype. Significant difference was found among the subjects with three different genotypes (P = 0.048) after adjusting the confounding factors. The median of Olive tail moment of the subjects carrying A allele (the genotypes of AA and GA) was 0.66 (0.44-1.31), which was significantly lower than that of subjects with GG genotype (P = 0.043). The A allele conferred a significantly reduced risk of DNA damage with the OR of 0.39 (95% CI: 0.15-0.99, P = 0.048). No significant association was found between the XRCC1Arg194Trp, ERCC1 C8092A, ERCC5 His1104Asp, ERCC6 Gly399Asp, GSTP1 Ile105Val, OGG1 Ser326Cys, XPC Lys939Gln, XPD Lys751Gln and DNA damage. CONCLUSION: The polymorphism of Arg399Gln in XRCC1 was associated with the Cr (VI)- induced DNA damage. XRCC1 Arg399Gln may serve as a genetic biomarker of susceptibility for Cr (VI)- induced DNA damage."
1290292,Fan et al. 2012,Long-term exposure to hexavalent chromium inhibits expression of tumor suppressor genes in cultured cells and in mice,"We have used mouse hepatoma cells in culture to study acute, short-term high-dose effects of hexavalent chromium on gene regulation directed by the polycyclic aromatic hydrocarbon benzo[a]pyrene (BaP). We find that the mixture engages three major signaling pathways: (i) activation of detoxification genes; (ii) induction of signal transduction effectors; and (iii) epigenetic modification of chromatin marks. Preliminary results in mice exposed to mixtures of low doses of Cr(VI) plus BaP indicate that all three pathways are likely to be engaged also in long-term effects resulting from exposure to environmentally relevant doses of the mixture that inhibit the expression of tumor suppressor genes. Given the toxicity and carcinogenicity of these mixtures, we expect that a two-way analytical approach, from cells in culture to biological effects in vivo and vice versa, will provide a better understanding of the molecular mechanisms responsible for the biological effects of mixtures. By focusing both the in vivo and the in vitro work into long-term, low-dose, environmentally relevant exposures, we expect to develop much needed information pertinent to the type of diseases found in human populations exposed to mixtures of environmental toxicants.","Long-term exposure to hexavalent chromium inhibits expression of tumor suppressor genes in cultured cells and in mice Abs: We have used mouse hepatoma cells in culture to study acute, short-term high-dose effects of hexavalent chromium on gene regulation directed by the polycyclic aromatic hydrocarbon benzo[a]pyrene (BaP). We find that the mixture engages three major signaling pathways: (i) activation of detoxification genes; (ii) induction of signal transduction effectors; and (iii) epigenetic modification of chromatin marks. Preliminary results in mice exposed to mixtures of low doses of Cr(VI) plus BaP indicate that all three pathways are likely to be engaged also in long-term effects resulting from exposure to environmentally relevant doses of the mixture that inhibit the expression of tumor suppressor genes. Given the toxicity and carcinogenicity of these mixtures, we expect that a two-way analytical approach, from cells in culture to biological effects in vivo and vice versa, will provide a better understanding of the molecular mechanisms responsible for the biological effects of mixtures. By focusing both the in vivo and the in vitro work into long-term, low-dose, environmentally relevant exposures, we expect to develop much needed information pertinent to the type of diseases found in human populations exposed to mixtures of environmental toxicants."
1290291,Wong et al. 2012,Metabolism of Cr(VI) by ascorbate but not glutathione is a low oxidant-generating process,"Genotoxic activity of hexavalent chromium (chromate) results from its reductive activation inside the cell. Cr(VI) metabolism in vivo is primarily driven by ascorbate (Asc) but in cultured cells by glutathione (GSH). Given the common use of cultured cells for mechanistic studies, it is important to establish whether Cr(VI) activated by Asc and GSH displays the same genotoxic properties. Using 2',7' dichlorofluorescin (DCFH) as a redox sensitive probe, we found that Asc-dependent reduction of Cr(VI) in vitro under physiological conditions generated 25-80 times lower yields of oxidants compared to GSH. When both reducers were present, Asc dominated Cr(VI) metabolism and inhibited DCFH oxidation. Consistent with the findings in defined chemical reactions, restoration of physiological levels of Asc in human lung H460 cells led to the loss of their hypersensitivity to clonogenic killing by Cr(VI) in the presence of methoxyamine, which inhibits base excision repair of oxidative DNA damage. Despite suppressed oxidative damage, Asc-containing cells formed a large number of DNA double-strand breaks after exposure to a dose of Cr(VI) corresponding to the drinking water standard of 100 ppb. Our results indicate that Asc-driven metabolism of Cr(VI) shifts its genotoxicity toward nonoxidative mechanisms.","Metabolism of Cr(VI) by ascorbate but not glutathione is a low oxidant-generating process Abs: Genotoxic activity of hexavalent chromium (chromate) results from its reductive activation inside the cell. Cr(VI) metabolism in vivo is primarily driven by ascorbate (Asc) but in cultured cells by glutathione (GSH). Given the common use of cultured cells for mechanistic studies, it is important to establish whether Cr(VI) activated by Asc and GSH displays the same genotoxic properties. Using 2',7' dichlorofluorescin (DCFH) as a redox sensitive probe, we found that Asc-dependent reduction of Cr(VI) in vitro under physiological conditions generated 25-80 times lower yields of oxidants compared to GSH. When both reducers were present, Asc dominated Cr(VI) metabolism and inhibited DCFH oxidation. Consistent with the findings in defined chemical reactions, restoration of physiological levels of Asc in human lung H460 cells led to the loss of their hypersensitivity to clonogenic killing by Cr(VI) in the presence of methoxyamine, which inhibits base excision repair of oxidative DNA damage. Despite suppressed oxidative damage, Asc-containing cells formed a large number of DNA double-strand breaks after exposure to a dose of Cr(VI) corresponding to the drinking water standard of 100 ppb. Our results indicate that Asc-driven metabolism of Cr(VI) shifts its genotoxicity toward nonoxidative mechanisms."
1290290,Thyssen et al. 2012,Chromium in leather footwear - risk assessment of chromium allergy and dermatitis,"<strong>BACKGROUND: </strong>Chromium-tanned leather footwear, which releases &gt;3 ppm hexavalent Cr(VI), may pose a risk of sensitizing and eliciting allergic dermatitis.<br /><br /><strong>OBJECTIVES: </strong>To determine the content and potential release of chromium in leather footwear and to discuss the prevention of chromium contact allergy and dermatitis.<br /><br /><strong>METHODS: </strong>Sixty pairs of leather shoes, sandals and boots (20 children's, 20 men's, and 20 women's) were purchased in Copenhagen and examined with X-ray fluorescence spectroscopy. Chromium was extracted according to the International Standard, ISO 17075. The detection level for Cr(VI) was 3 ppm.<br /><br /><strong>RESULTS: </strong>Chromium was identified in 95% of leather footwear products, the median content being 1.7% (range 0-3.3%). No association with store category or footwear category was found. A tendency for there to be a higher chromium content in footwear with high prices was shown (p(trend) = 0.001). Cr(VI) was extracted from 44% of 18 footwear products, and, in three items, more than 10 ppm was extracted. One shoe had 62 ppm Cr(VI) extracted. Sandals seemed to be over-represented among footwear with detectable Cr(VI). Cr(III) extraction reached a median value of 152 ppm.<br /><br /><strong>CONCLUSIONS: </strong>Most leather footwear contained chromium. Cr(VI) was extracted from a high proportion of leather footwear; this poses a risk of sensitization.","Chromium in leather footwear - risk assessment of chromium allergy and dermatitis Abs: <strong>BACKGROUND: </strong>Chromium-tanned leather footwear, which releases &gt;3 ppm hexavalent Cr(VI), may pose a risk of sensitizing and eliciting allergic dermatitis.<br /><br /><strong>OBJECTIVES: </strong>To determine the content and potential release of chromium in leather footwear and to discuss the prevention of chromium contact allergy and dermatitis.<br /><br /><strong>METHODS: </strong>Sixty pairs of leather shoes, sandals and boots (20 children's, 20 men's, and 20 women's) were purchased in Copenhagen and examined with X-ray fluorescence spectroscopy. Chromium was extracted according to the International Standard, ISO 17075. The detection level for Cr(VI) was 3 ppm.<br /><br /><strong>RESULTS: </strong>Chromium was identified in 95% of leather footwear products, the median content being 1.7% (range 0-3.3%). No association with store category or footwear category was found. A tendency for there to be a higher chromium content in footwear with high prices was shown (p(trend) = 0.001). Cr(VI) was extracted from 44% of 18 footwear products, and, in three items, more than 10 ppm was extracted. One shoe had 62 ppm Cr(VI) extracted. Sandals seemed to be over-represented among footwear with detectable Cr(VI). Cr(III) extraction reached a median value of 152 ppm.<br /><br /><strong>CONCLUSIONS: </strong>Most leather footwear contained chromium. Cr(VI) was extracted from a high proportion of leather footwear; this poses a risk of sensitization."
1290289,Selcuk et al. 2012,Chromium picolinate and chromium histidinate protects against renal dysfunction by modulation of NF-?B pathway in high-fat diet fed and Streptozotocin-induced diabetic rats,"<strong>UNLABELLED: </strong>ABSTRACT:<br /><br /><strong>BACKGROUND: </strong>Diabetic nephropathy is one of major complications of diabetes mellitus. Although chromium is an essential element for carbohydrate and lipid metabolism, its effects on diabetic nephropathy are not well understood. The present study was conducted to investigate the effects of chromium picolinate (CrPic) and chromium histidinate (CrHis) on nuclear factor-kappa B (NF-?B) and nuclear factor-E2-related factor-2 (Nrf2) pathway in the rat kidney.<br /><br /><strong>METHODS: </strong>Male Wistar rats were divided into six groups. Group I received a standard diet (8% fat) and served as a control; Group II was fed with a standard diet and received CrPic; Group III was fed with a standard diet and received CrHis; Group IV received a high fat diet (HFD, 40% fat) for 2 weeks and then were injected with streptozotocin (STZ) (HFD/STZ); Group V was treated as group IV (HFD/STZ) but supplemented with CrPic for 12 weeks. Group VI was treated as group IV (HFD/STZ) but supplemented with CrHis.<br /><br /><strong>RESULTS: </strong>The increased NF-?? p65 in the HFD/STZ group was inhibited by CrPic and CrHis supplementation (P &lt; 0.05). In STZ-treated rats, a significant decrease in levels of nuclear factor of kappa light polypeptide gene enhancer in B-cells inhibitor, alpha (I?B?) was found in kidney tissues when compared to control rats (P &lt; 0.05). A significant increase in the levels of I?B? was observed in CrPic- and CrHis-treated rats when compared with STZ-treated rats. Renal Nrf2 levels were significantly decreased in diabetic rats compared with the control rats. There was a higher tendency for increase of kidney Nrf2 level and decrease in kidney NF?Bp65 levels and 4- hydroxyl nonenal (4-HNE) protein adducts (P &lt; 0.05) in diabetic rats.<br /><br /><strong>CONCLUSION: </strong>Our result show that in kidney tissue CrHis/CrPic increases Nrf2 level, parallelly decreases NF-?B and partially restores I?B? levels in HFD/STZ group, suggesting that CrPic and CrHis may play a role in antioxidant defense system via the Nrf2 pathway by reducing inflammation through NF-?? p65 inhibition. Moreover, a greater reduction in NF-?B expression and greater increases in expressions of I?B? and Nrf2 in diabetic rats supplemented with CrHis than rats supplemented with CrPic suggest that CrHis has more favorable effects than CrPic.","Chromium picolinate and chromium histidinate protects against renal dysfunction by modulation of NF-?B pathway in high-fat diet fed and Streptozotocin-induced diabetic rats Abs: <strong>UNLABELLED: </strong>ABSTRACT:<br /><br /><strong>BACKGROUND: </strong>Diabetic nephropathy is one of major complications of diabetes mellitus. Although chromium is an essential element for carbohydrate and lipid metabolism, its effects on diabetic nephropathy are not well understood. The present study was conducted to investigate the effects of chromium picolinate (CrPic) and chromium histidinate (CrHis) on nuclear factor-kappa B (NF-?B) and nuclear factor-E2-related factor-2 (Nrf2) pathway in the rat kidney.<br /><br /><strong>METHODS: </strong>Male Wistar rats were divided into six groups. Group I received a standard diet (8% fat) and served as a control; Group II was fed with a standard diet and received CrPic; Group III was fed with a standard diet and received CrHis; Group IV received a high fat diet (HFD, 40% fat) for 2 weeks and then were injected with streptozotocin (STZ) (HFD/STZ); Group V was treated as group IV (HFD/STZ) but supplemented with CrPic for 12 weeks. Group VI was treated as group IV (HFD/STZ) but supplemented with CrHis.<br /><br /><strong>RESULTS: </strong>The increased NF-?? p65 in the HFD/STZ group was inhibited by CrPic and CrHis supplementation (P &lt; 0.05). In STZ-treated rats, a significant decrease in levels of nuclear factor of kappa light polypeptide gene enhancer in B-cells inhibitor, alpha (I?B?) was found in kidney tissues when compared to control rats (P &lt; 0.05). A significant increase in the levels of I?B? was observed in CrPic- and CrHis-treated rats when compared with STZ-treated rats. Renal Nrf2 levels were significantly decreased in diabetic rats compared with the control rats. There was a higher tendency for increase of kidney Nrf2 level and decrease in kidney NF?Bp65 levels and 4- hydroxyl nonenal (4-HNE) protein adducts (P &lt; 0.05) in diabetic rats.<br /><br /><strong>CONCLUSION: </strong>Our result show that in kidney tissue CrHis/CrPic increases Nrf2 level, parallelly decreases NF-?B and partially restores I?B? levels in HFD/STZ group, suggesting that CrPic and CrHis may play a role in antioxidant defense system via the Nrf2 pathway by reducing inflammation through NF-?? p65 inhibition. Moreover, a greater reduction in NF-?B expression and greater increases in expressions of I?B? and Nrf2 in diabetic rats supplemented with CrHis than rats supplemented with CrPic suggest that CrHis has more favorable effects than CrPic."
1290288,Soudani et al. 2012,Ameliorating effect of selenium on chromium (VI)-induced oxidative damage in the brain of adult rats,"Chromium is known for its wide toxic manifestations. This experiment aims to evaluate the effect of selenium against oxidative stress induced by chromium in the cerebrum and cerebellum. Female Wistar rats were randomly divided into four groups of six each: group I served as controls which received the standard diet; group II received drinking water K(2)Cr(2)O(7) alone (700 ppm); group III received both K(2)Cr(2)O(7) and Se (0.5 mg Na(2)SeO(3)/kg of diet); and group IV received Se (0.5 mg/kg of diet) for 3 weeks. The exposure of rats to K(2)Cr(2)O(7) promoted oxidative stress in the cerebrum and cerebellum with an increase in malondialdehyde and a decrease of nonenzymatic antioxidant levels such as glutathione, nonprotein thiol, and vitamin C. An increase of enzyme activities like catalase, glutathione peroxidase, and superoxide dismutase activities was also observed. Acetylcholinesterase activity was inhibited after treatment with K(2)Cr(2)O(7). Co-administration of Se restored the parameters cited above. The histopathological findings confirmed the biochemical results.","Ameliorating effect of selenium on chromium (VI)-induced oxidative damage in the brain of adult rats Abs: Chromium is known for its wide toxic manifestations. This experiment aims to evaluate the effect of selenium against oxidative stress induced by chromium in the cerebrum and cerebellum. Female Wistar rats were randomly divided into four groups of six each: group I served as controls which received the standard diet; group II received drinking water K(2)Cr(2)O(7) alone (700 ppm); group III received both K(2)Cr(2)O(7) and Se (0.5 mg Na(2)SeO(3)/kg of diet); and group IV received Se (0.5 mg/kg of diet) for 3 weeks. The exposure of rats to K(2)Cr(2)O(7) promoted oxidative stress in the cerebrum and cerebellum with an increase in malondialdehyde and a decrease of nonenzymatic antioxidant levels such as glutathione, nonprotein thiol, and vitamin C. An increase of enzyme activities like catalase, glutathione peroxidase, and superoxide dismutase activities was also observed. Acetylcholinesterase activity was inhibited after treatment with K(2)Cr(2)O(7). Co-administration of Se restored the parameters cited above. The histopathological findings confirmed the biochemical results."
1290287,Reynolds et al. 2012,"Undetectable role of oxidative DNA damage in cell cycle, cytotoxic and clastogenic effects of Cr(VI) in human lung cells with restored ascorbate levels","Cultured human cells are invaluable biological models for mechanistic studies of genotoxic chemicals and drugs. Continuing replacement of animals in toxicity testing will further increase the importance of in vitro cell systems, which should accurately reproduce key in vivo characteristics of toxicants such as their profiles of metabolites and DNA lesions. In this work, we examined how a common severe deficiency of cultured cells in ascorbate (Asc) impacts the formation of oxidative DNA damage by hexavalent chromium (chromate). Cr(VI) is reductively activated inside the cells by both Asc and small thiols but with different rates and spectra of intermediates and DNA adducts. We found that Cr(VI) exposure of H460 human lung epithelial cells in standard culture (&lt;0.01 mM cellular Asc) induced biologically significant amounts of oxidative DNA damage. Inhibition of oxidative damage repair in these cells by stable XRCC1 knockdown strongly enhanced cytotoxic effects of Cr(VI) and led to depletion of cells from G(1) and accumulation in S and G(2) phases. However, restoration of physiological levels of Asc (? 1 mM) completely eliminated Cr(VI) hypersensitivity of XRCC1 knockdown. The induction of chromosomal breaks assayed by the micronucleus test in Asc-restored H460, primary human lung fibroblasts, and CHO cells was also unaffected by the XRCC1 status. Centromere-negative (clastogenic) micronuclei accounted for 80-90% of all Cr(VI)-induced micronuclei. Consistent with the micronuclei results, Asc-restored cells also showed no increase in the levels of poly(ADP-ribose), which is a biochemical marker of single-stranded breaks. Asc had no effect on cytotoxicity of O(6)-methylguanine, a lesion produced by direct DNA alkylation. Overall, our results indicate that the presence of physiological levels of Asc strongly suppresses pro-oxidant pathways in Cr(VI) metabolism and that the use of standard cell cultures creates a distorted profile of its genotoxic properties.","Undetectable role of oxidative DNA damage in cell cycle, cytotoxic and clastogenic effects of Cr(VI) in human lung cells with restored ascorbate levels Abs: Cultured human cells are invaluable biological models for mechanistic studies of genotoxic chemicals and drugs. Continuing replacement of animals in toxicity testing will further increase the importance of in vitro cell systems, which should accurately reproduce key in vivo characteristics of toxicants such as their profiles of metabolites and DNA lesions. In this work, we examined how a common severe deficiency of cultured cells in ascorbate (Asc) impacts the formation of oxidative DNA damage by hexavalent chromium (chromate). Cr(VI) is reductively activated inside the cells by both Asc and small thiols but with different rates and spectra of intermediates and DNA adducts. We found that Cr(VI) exposure of H460 human lung epithelial cells in standard culture (&lt;0.01 mM cellular Asc) induced biologically significant amounts of oxidative DNA damage. Inhibition of oxidative damage repair in these cells by stable XRCC1 knockdown strongly enhanced cytotoxic effects of Cr(VI) and led to depletion of cells from G(1) and accumulation in S and G(2) phases. However, restoration of physiological levels of Asc (? 1 mM) completely eliminated Cr(VI) hypersensitivity of XRCC1 knockdown. The induction of chromosomal breaks assayed by the micronucleus test in Asc-restored H460, primary human lung fibroblasts, and CHO cells was also unaffected by the XRCC1 status. Centromere-negative (clastogenic) micronuclei accounted for 80-90% of all Cr(VI)-induced micronuclei. Consistent with the micronuclei results, Asc-restored cells also showed no increase in the levels of poly(ADP-ribose), which is a biochemical marker of single-stranded breaks. Asc had no effect on cytotoxicity of O(6)-methylguanine, a lesion produced by direct DNA alkylation. Overall, our results indicate that the presence of physiological levels of Asc strongly suppresses pro-oxidant pathways in Cr(VI) metabolism and that the use of standard cell cultures creates a distorted profile of its genotoxic properties."
1290286,Chan et al. ,In vivo chromium-enhanced MRI of the retina,"Chromium (Cr) has been used histologically to stabilize lipid fractions in the retina and is suggested to enhance oxidizable lipids in brain MRI. This study explored the feasibility, sensitivity, and specificity of in vivo chromium-enhanced MRI of retinal lipids by determining its spatiotemporal profiles and toxic effect after intravitreal Cr(VI) injection to normal adult rats. One day after 3 ?L Cr(VI) administration at 1-100 mM, the retina exhibited a dose-dependent increase in T(1) -weighted hyperintensity until 50 mM. Time-dependently, significant T(1) -weighted hyperintensity persisted up to 2 weeks after 10 mM Cr(VI) administration. Three-dimensional chromium-enhanced MRI of ex vivo normal eyes at isotropic 50-?m resolution showed at least five alternating bands across retinal layers, with the outermost layer being the brightest. This agreed with histology indicating alternating lipid contents with the highest level in the photoreceptor layer of the outer retina. Although Cr(VI) reduction may induce oxidative stress and depolymerize microtubules, manganese-enhanced MRI after chromium-enhanced MRI showed a dose-dependent effect of Cr toxicity on manganese uptake and axonal transport along the visual pathway. These results potentiated future longitudinal chromium-enhanced MRI studies on retinal lipid metabolism upon further optimization of Cr doses with visual cell viability. Magn Reson Med, 2011. © 2011 Wiley Periodicals, Inc.","In vivo chromium-enhanced MRI of the retina Abs: Chromium (Cr) has been used histologically to stabilize lipid fractions in the retina and is suggested to enhance oxidizable lipids in brain MRI. This study explored the feasibility, sensitivity, and specificity of in vivo chromium-enhanced MRI of retinal lipids by determining its spatiotemporal profiles and toxic effect after intravitreal Cr(VI) injection to normal adult rats. One day after 3 ?L Cr(VI) administration at 1-100 mM, the retina exhibited a dose-dependent increase in T(1) -weighted hyperintensity until 50 mM. Time-dependently, significant T(1) -weighted hyperintensity persisted up to 2 weeks after 10 mM Cr(VI) administration. Three-dimensional chromium-enhanced MRI of ex vivo normal eyes at isotropic 50-?m resolution showed at least five alternating bands across retinal layers, with the outermost layer being the brightest. This agreed with histology indicating alternating lipid contents with the highest level in the photoreceptor layer of the outer retina. Although Cr(VI) reduction may induce oxidative stress and depolymerize microtubules, manganese-enhanced MRI after chromium-enhanced MRI showed a dose-dependent effect of Cr toxicity on manganese uptake and axonal transport along the visual pathway. These results potentiated future longitudinal chromium-enhanced MRI studies on retinal lipid metabolism upon further optimization of Cr doses with visual cell viability. Magn Reson Med, 2011. © 2011 Wiley Periodicals, Inc."
1290285,Sobol and  Schiestl 2012,Intracellular and extracellular factors influencing Cr(VI) and Cr(III) genotoxicity,"Cr(VI) is a human and animal carcinogen. Cr(VI) does not interact directly with DNA and thus its genotoxicity is attributed to its intracellular reduction to Cr(III) via reactive intermediates. The resulting types of DNA damage can be grouped into two categories: (1) oxidative DNA damage and (2) Cr(III)-DNA interactions. This study examines the molecular mechanism of Cr(VI) and Cr(III) genotoxicity in an intact cell. A system screening for DNA deletions (DEL assay) was used to compare induction of chromosomal rearrangements in the yeast Saccharomyces cerevisiae following Cr(VI) and Cr(III) exposure. Both forms of chromium induced DNA deletions albeit with different dose-response curves. N-acetylcysteine had a protective effect against Cr(VI) genotoxicity at high exposure doses but had no protective effect at lower doses or against Cr(III). An oxidative DNA damage repair mutant was hypersensitive to Cr(VI) only at high exposure and the mutant was not hypersensitive to Cr(III) exposure. These data imply that oxidative stress is involved in Cr(VI) genotoxicity at high exposure concentrations and not so in Cr(III). The Cr(III)-DNA interaction appears to be an important genotoxic lesion following Cr(VI) exposure at low-exposure concentrations. The CAN forward mutation assay revealed that within the concentration ranges used for this study, Cr(III) does not cause point mutations and Cr(VI) causes a mild but statistically significant increase in point mutation only at the highest concentration tested. This study reveals that DNA deletions occurring as a result of intrachromosomal homologous recombination are a useful endpoint for studying chromium genotoxicity.","Intracellular and extracellular factors influencing Cr(VI) and Cr(III) genotoxicity Abs: Cr(VI) is a human and animal carcinogen. Cr(VI) does not interact directly with DNA and thus its genotoxicity is attributed to its intracellular reduction to Cr(III) via reactive intermediates. The resulting types of DNA damage can be grouped into two categories: (1) oxidative DNA damage and (2) Cr(III)-DNA interactions. This study examines the molecular mechanism of Cr(VI) and Cr(III) genotoxicity in an intact cell. A system screening for DNA deletions (DEL assay) was used to compare induction of chromosomal rearrangements in the yeast Saccharomyces cerevisiae following Cr(VI) and Cr(III) exposure. Both forms of chromium induced DNA deletions albeit with different dose-response curves. N-acetylcysteine had a protective effect against Cr(VI) genotoxicity at high exposure doses but had no protective effect at lower doses or against Cr(III). An oxidative DNA damage repair mutant was hypersensitive to Cr(VI) only at high exposure and the mutant was not hypersensitive to Cr(III) exposure. These data imply that oxidative stress is involved in Cr(VI) genotoxicity at high exposure concentrations and not so in Cr(III). The Cr(III)-DNA interaction appears to be an important genotoxic lesion following Cr(VI) exposure at low-exposure concentrations. The CAN forward mutation assay revealed that within the concentration ranges used for this study, Cr(III) does not cause point mutations and Cr(VI) causes a mild but statistically significant increase in point mutation only at the highest concentration tested. This study reveals that DNA deletions occurring as a result of intrachromosomal homologous recombination are a useful endpoint for studying chromium genotoxicity."
1290284,Tagliari et al. 2004,Oxidative stress damage in the liver of fish and rats receiving an intraperitoneal injection of hexavalent chromium as evaluated by chemiluminescence,"The livers fractions of Oreochromis niloticus (Tilapia) and Wistar rats taken from treated animals to single intraperitoneal doses of hexavalent chromium (K(2)Cr(2)O(7)), were analyzed for tert butyl hydroperoxide-initiated chemiluminescence (CL), lipid peroxidation using thiobarbituric acid reactive substances (TBARS), enzymes superoxide dismutase (SOD) and catalase activities, and the quantification of cytochromes P450 and b5. The CL time course curve was significantly higher in O. niloticus treated with Cr(VI) at all times studied. The maximum CL was observed after 24h of exposure. The CL mean ratio treated/control was 4.6 and the initial velocity (V(0)) increased 7.4 times at 24h of intoxication. The TBARS levels however increased only 24h after intoxication. The CL time course curve was significantly higher in rats treated with Cr(VI) as early as 3h after intoxication. The maximum CL occurred 24h after exposure. The CL mean ratio treated/control was 2.1 and the V(0) increased 3.8 times at 24h of intoxication. On the contrary, was not observed any increase in TBARS in this study. Compared to the controls, in fish, SOD activity increased significantly only 24h after of exposure. In rats, there was a significant increase in SOD activity after 3 and 24h of intoxication. There was no catalase activity, nor cytochrome P450 and cytochrome b5 variation in both species studied. Through CL approach, it was possible to detect oxidative stress as early as 15min in fish and 3h in rats. Also a marked oxidative stress was revealed by the increased CL parameters that at 24h of intoxication was accompanied by arose SOD activity in liver of O. niloticus and Wistar rats and increased TBARS in O. niloticus. In addition, it was possible to show higher levels of oxidative stress in fish compared to the rat in spite of the dose to be four times smaller. Furthermore, CL provide a sensitive method for possible use to detect earlier biological impact in contaminated environments.","Oxidative stress damage in the liver of fish and rats receiving an intraperitoneal injection of hexavalent chromium as evaluated by chemiluminescence Abs: The livers fractions of Oreochromis niloticus (Tilapia) and Wistar rats taken from treated animals to single intraperitoneal doses of hexavalent chromium (K(2)Cr(2)O(7)), were analyzed for tert butyl hydroperoxide-initiated chemiluminescence (CL), lipid peroxidation using thiobarbituric acid reactive substances (TBARS), enzymes superoxide dismutase (SOD) and catalase activities, and the quantification of cytochromes P450 and b5. The CL time course curve was significantly higher in O. niloticus treated with Cr(VI) at all times studied. The maximum CL was observed after 24h of exposure. The CL mean ratio treated/control was 4.6 and the initial velocity (V(0)) increased 7.4 times at 24h of intoxication. The TBARS levels however increased only 24h after intoxication. The CL time course curve was significantly higher in rats treated with Cr(VI) as early as 3h after intoxication. The maximum CL occurred 24h after exposure. The CL mean ratio treated/control was 2.1 and the V(0) increased 3.8 times at 24h of intoxication. On the contrary, was not observed any increase in TBARS in this study. Compared to the controls, in fish, SOD activity increased significantly only 24h after of exposure. In rats, there was a significant increase in SOD activity after 3 and 24h of intoxication. There was no catalase activity, nor cytochrome P450 and cytochrome b5 variation in both species studied. Through CL approach, it was possible to detect oxidative stress as early as 15min in fish and 3h in rats. Also a marked oxidative stress was revealed by the increased CL parameters that at 24h of intoxication was accompanied by arose SOD activity in liver of O. niloticus and Wistar rats and increased TBARS in O. niloticus. In addition, it was possible to show higher levels of oxidative stress in fish compared to the rat in spite of the dose to be four times smaller. Furthermore, CL provide a sensitive method for possible use to detect earlier biological impact in contaminated environments."
1290283,Acharya et al. 2004,Status of antioxidant defense system in chromium-induced Swiss mice tissues,"Based on epidemiological studies, chromium(VI) compounds are considered as more toxic and carcinogenic than chromium(III) compounds. The deleterious effects of chromium(VI) compounds are diversified affecting almost all the organ systems in a wide variety of animals. The present study, describes the cytotoxic effects of chromium trioxide, a well-known chromium(VI) compound in three tissues (liver, kidney, lungs) of male Swiss mice during post-treatment phase (5th-8th week after treatment). Lipid peroxidation, an index of oxidative stress, was determined as thiobarbituric acid-reactive substances (TBA-Rs) in mice tissues dosed with a single intraperitoneal injection of chromium trioxide (1mg/kg body weight). Tissue specific and statistically significant increases in TBA-Rs was observed in chromium-treated mice groups compared to controls in all the weeks of post-treatment. Endogenous ascorbic acid (vit-C) content of tissues which happens to be one of the stable antioxidants, declined significantly due to chromium-induction. Activity of antioxidative enzymes like superoxide dismutase (SOD), catalase (CT) and peroxidase (PD) was significantly inhibited among chromium-injected mice groups compared to respective controls. Protective role of ascorbic acid and the antioxidative enzymes in chromium-induced cytotoxicity in mice is discussed.","Status of antioxidant defense system in chromium-induced Swiss mice tissues Abs: Based on epidemiological studies, chromium(VI) compounds are considered as more toxic and carcinogenic than chromium(III) compounds. The deleterious effects of chromium(VI) compounds are diversified affecting almost all the organ systems in a wide variety of animals. The present study, describes the cytotoxic effects of chromium trioxide, a well-known chromium(VI) compound in three tissues (liver, kidney, lungs) of male Swiss mice during post-treatment phase (5th-8th week after treatment). Lipid peroxidation, an index of oxidative stress, was determined as thiobarbituric acid-reactive substances (TBA-Rs) in mice tissues dosed with a single intraperitoneal injection of chromium trioxide (1mg/kg body weight). Tissue specific and statistically significant increases in TBA-Rs was observed in chromium-treated mice groups compared to controls in all the weeks of post-treatment. Endogenous ascorbic acid (vit-C) content of tissues which happens to be one of the stable antioxidants, declined significantly due to chromium-induction. Activity of antioxidative enzymes like superoxide dismutase (SOD), catalase (CT) and peroxidase (PD) was significantly inhibited among chromium-injected mice groups compared to respective controls. Protective role of ascorbic acid and the antioxidative enzymes in chromium-induced cytotoxicity in mice is discussed."
1290282,Zhitkovich 2011,"Chromium in drinking water: sources, metabolism, and cancer risks","Drinking water supplies in many geographic areas contain chromium in the +3 and +6 oxidation states. Public health concerns are centered on the presence of hexavalent Cr that is classified as a known human carcinogen via inhalation. Cr(VI) has high environmental mobility and can originate from anthropogenic and natural sources. Acidic environments with high organic content promote the reduction of Cr(VI) to nontoxic Cr(III). The opposite process of Cr(VI) formation from Cr(III) also occurs, particularly in the presence of common minerals containing Mn(IV) oxides. Limited epidemiological evidence for Cr(VI) ingestion is suggestive of elevated risks for stomach cancers. Exposure of animals to Cr(VI) in drinking water induced tumors in the alimentary tract, with linear and supralinear responses in the mouse small intestine. Chromate, the predominant form of Cr(VI) at neutral pH, is taken up by all cells through sulfate channels and is activated nonenzymatically by ubiquitously present ascorbate and small thiols. The most abundant form of DNA damage induced by Cr(VI) is Cr-DNA adducts, which cause mutations and chromosomal breaks. Emerging evidence points to two-way interactions between DNA damage and epigenetic changes that collectively determine the spectrum of genomic rearrangements and profiles of gene expression in tumors. Extensive formation of DNA adducts, clear positivity in genotoxicity assays with high predictive values for carcinogenicity, the shape of tumor-dose responses in mice, and a biological signature of mutagenic carcinogens (multispecies, multisite, and trans-sex tumorigenic potency) strongly support the importance of the DNA-reactive mutagenic mechanisms in carcinogenic effects of Cr(VI). Bioavailability results and kinetic considerations suggest that 10-20% of ingested low-dose Cr(VI) escapes human gastric inactivation. The directly mutagenic mode of action and the incompleteness of gastric detoxification argue against a threshold in low-dose extrapolation of cancer risk for ingested Cr(VI).","Chromium in drinking water: sources, metabolism, and cancer risks Abs: Drinking water supplies in many geographic areas contain chromium in the +3 and +6 oxidation states. Public health concerns are centered on the presence of hexavalent Cr that is classified as a known human carcinogen via inhalation. Cr(VI) has high environmental mobility and can originate from anthropogenic and natural sources. Acidic environments with high organic content promote the reduction of Cr(VI) to nontoxic Cr(III). The opposite process of Cr(VI) formation from Cr(III) also occurs, particularly in the presence of common minerals containing Mn(IV) oxides. Limited epidemiological evidence for Cr(VI) ingestion is suggestive of elevated risks for stomach cancers. Exposure of animals to Cr(VI) in drinking water induced tumors in the alimentary tract, with linear and supralinear responses in the mouse small intestine. Chromate, the predominant form of Cr(VI) at neutral pH, is taken up by all cells through sulfate channels and is activated nonenzymatically by ubiquitously present ascorbate and small thiols. The most abundant form of DNA damage induced by Cr(VI) is Cr-DNA adducts, which cause mutations and chromosomal breaks. Emerging evidence points to two-way interactions between DNA damage and epigenetic changes that collectively determine the spectrum of genomic rearrangements and profiles of gene expression in tumors. Extensive formation of DNA adducts, clear positivity in genotoxicity assays with high predictive values for carcinogenicity, the shape of tumor-dose responses in mice, and a biological signature of mutagenic carcinogens (multispecies, multisite, and trans-sex tumorigenic potency) strongly support the importance of the DNA-reactive mutagenic mechanisms in carcinogenic effects of Cr(VI). Bioavailability results and kinetic considerations suggest that 10-20% of ingested low-dose Cr(VI) escapes human gastric inactivation. The directly mutagenic mode of action and the incompleteness of gastric detoxification argue against a threshold in low-dose extrapolation of cancer risk for ingested Cr(VI)."
1290281,Levina and  Lay 2011,Metal-based anti-diabetic drugs: advances and challenges,"The current status and likely future directions of complexes of V(V/IV), Cr(III), Mo(VI), W(VI), Zn(II), Cu(II), and Mn(III) as potential oral drugs against type 2 diabetes are reviewed. We propose a unified model of extra- and intracellular mechanisms of anti-diabetic efficacies of V(V/IV), Mo(VI), W(VI), and Cr(III), centred on high-oxidation-state oxido/peroxido species that inhibit protein tyrosine phosphatases (PTPs) involved in insulin signalling. The postulated oxidative mechanism of anti-diabetic activity of Cr(III) via carcinogenic Cr(VI/V) (which adds to safety concerns) is consistent with recent clinical trials on Cr(III) picolinate, where activity was apparent only in patients with poorly controlled diabetes (high oxidative stress), and the correlation between the anti-diabetic activities and ease of oxidation of Cr(III) supplements and their metabolites in vivo. Zn(II) and Cu(II) anti-diabetics act via different mechanisms and are unlikely to be used as specific anti-diabetics due to their diverse and unpredictable biological activities. Hence, future research directions are likely to centre on enhancing the bioavailability and selectivity of V(V/IV), Mo(VI), or W(VI) drugs. The strategy of potentiating circulating insulin with metal ions has distinct therapeutic advantages over interventions that stimulate the release of more insulin, or use insulin mimetics, because of many adverse side-effects of increased levels of insulin, including increased risks of cancer and cardiovascular diseases.","Metal-based anti-diabetic drugs: advances and challenges Abs: The current status and likely future directions of complexes of V(V/IV), Cr(III), Mo(VI), W(VI), Zn(II), Cu(II), and Mn(III) as potential oral drugs against type 2 diabetes are reviewed. We propose a unified model of extra- and intracellular mechanisms of anti-diabetic efficacies of V(V/IV), Mo(VI), W(VI), and Cr(III), centred on high-oxidation-state oxido/peroxido species that inhibit protein tyrosine phosphatases (PTPs) involved in insulin signalling. The postulated oxidative mechanism of anti-diabetic activity of Cr(III) via carcinogenic Cr(VI/V) (which adds to safety concerns) is consistent with recent clinical trials on Cr(III) picolinate, where activity was apparent only in patients with poorly controlled diabetes (high oxidative stress), and the correlation between the anti-diabetic activities and ease of oxidation of Cr(III) supplements and their metabolites in vivo. Zn(II) and Cu(II) anti-diabetics act via different mechanisms and are unlikely to be used as specific anti-diabetics due to their diverse and unpredictable biological activities. Hence, future research directions are likely to centre on enhancing the bioavailability and selectivity of V(V/IV), Mo(VI), or W(VI) drugs. The strategy of potentiating circulating insulin with metal ions has distinct therapeutic advantages over interventions that stimulate the release of more insulin, or use insulin mimetics, because of many adverse side-effects of increased levels of insulin, including increased risks of cancer and cardiovascular diseases."
1290280,Rodriguez et al. 2011,"Cr(VI) induces DNA damage, cell cycle arrest and polyploidization: a flow cytometric and comet assay study in Pisum sativum","Chromium(VI) is recognized as the most toxic valency of Cr, but its genotoxicity and cytostaticity in plants is still poorly studied. In order to analyze Cr(VI) cyto- and gentotoxicity, Pisum sativum L. plants were grown in soil and watered with solutions with different concentrations of Cr up to 2000 mg/L. After 28 days of exposure, leaves showed no significant variations in either cell cycle dynamics or ploidy level. As for DNA damage, flow cytometric (FCM) histograms showed significant differences in full peak coefficient of variation (FPCV) values, suggesting clastogenicity. This is paralleled by the Comet assay results, showing an increase in DNA damage for 1000 and 2000 mg/L. In roots, exposure to 2000 mg/L resulted in cell cycle arrest at the G(2)/M checkpoint. It was also verified that under the same conditions 40% of the individuals analyzed suffered polyploidization having both 2C and 4C levels. DNA damage analysis by the Comet assay and FCM revealed dose-dependent increases in DNA damage and FPCV. Through this, we have unequivocally demonstrated for the first time in plants that Cr exposure can result in DNA damage, cell cycle arrest, and polyploidization. Moreover, we critically compare the validity of the Comet assay and FCM in evaluating cytogenetic toxicity tests in plants and demonstrate that the data provided by both techniques complement each other and present high correlation levels. In conclusion, the data presented provides new insight on Cr effects in plants in general and supports the use of the parameters tested in this study as reliable endpoints for this metal toxicity in plants.","Cr(VI) induces DNA damage, cell cycle arrest and polyploidization: a flow cytometric and comet assay study in Pisum sativum Abs: Chromium(VI) is recognized as the most toxic valency of Cr, but its genotoxicity and cytostaticity in plants is still poorly studied. In order to analyze Cr(VI) cyto- and gentotoxicity, Pisum sativum L. plants were grown in soil and watered with solutions with different concentrations of Cr up to 2000 mg/L. After 28 days of exposure, leaves showed no significant variations in either cell cycle dynamics or ploidy level. As for DNA damage, flow cytometric (FCM) histograms showed significant differences in full peak coefficient of variation (FPCV) values, suggesting clastogenicity. This is paralleled by the Comet assay results, showing an increase in DNA damage for 1000 and 2000 mg/L. In roots, exposure to 2000 mg/L resulted in cell cycle arrest at the G(2)/M checkpoint. It was also verified that under the same conditions 40% of the individuals analyzed suffered polyploidization having both 2C and 4C levels. DNA damage analysis by the Comet assay and FCM revealed dose-dependent increases in DNA damage and FPCV. Through this, we have unequivocally demonstrated for the first time in plants that Cr exposure can result in DNA damage, cell cycle arrest, and polyploidization. Moreover, we critically compare the validity of the Comet assay and FCM in evaluating cytogenetic toxicity tests in plants and demonstrate that the data provided by both techniques complement each other and present high correlation levels. In conclusion, the data presented provides new insight on Cr effects in plants in general and supports the use of the parameters tested in this study as reliable endpoints for this metal toxicity in plants."
1290278,Mangiameli et al. 2011,New insights on the mechanism of oxidation of D-galacturonic acid by hypervalent chromium,"The pollutant Cr(VI) is known to be very carcinogenic. In conditions of excess of Cr(VI), oxidation of D-galacturonic acid (Galur), the major metabolite of pectin, yields d-galactaric acid (Galar) and Cr(III). The redox reaction takes place through a multistep mechanism involving formation of intermediate Cr(II/IV) and Cr(V) species. The mechanism combines one- and two-electron pathways for the reduction of Cr(IV) by the organic substrate: Cr(VI)? Cr(IV)? Cr(II) and Cr(VI)? Cr(IV)? Cr(III). This is supported by the observation of the optical absorption spectra of Cr(VI) esters, free radicals, CrO(2)(2+) (superoxoCr(III) ion) and oxo-Cr(V) complexes. Cr(IV) cannot be directly detected; however, formation of CrO(2)(2+) provides indirect evidence for the intermediacy of Cr(II/IV). Cr(IV) reacts with Galur much faster than Cr(V) and Cr(VI) do. The analysis of the reaction kinetics via optical absorption spectroscopy shows that the Cr(IV)-Galur reaction rate inversely depends on [H(+)]. Nevertheless, high [H(+)] still does not facilitate accumulation of Cr(IV) in the Cr(VI)-Galur mixture. Cr(VI) and the intermediate Cr(V) react with Galur at comparable rates; therefore the build-up and decay of Cr(V) accompany the decay of Cr(VI). The complete rate laws for the Cr(VI), Cr(V) and Cr(IV)-Galur redox reaction are here derived in detail. Furthermore, the nature of the five-co-ordinated oxo-Cr(V) bischelate complexes formed in Cr(VI)-Galur mixtures at pH 1-5 is investigated using continuous-wave and pulsed electron paramagnetic resonance (EPR) and density functional theory (DFT).","New insights on the mechanism of oxidation of D-galacturonic acid by hypervalent chromium Abs: The pollutant Cr(VI) is known to be very carcinogenic. In conditions of excess of Cr(VI), oxidation of D-galacturonic acid (Galur), the major metabolite of pectin, yields d-galactaric acid (Galar) and Cr(III). The redox reaction takes place through a multistep mechanism involving formation of intermediate Cr(II/IV) and Cr(V) species. The mechanism combines one- and two-electron pathways for the reduction of Cr(IV) by the organic substrate: Cr(VI)? Cr(IV)? Cr(II) and Cr(VI)? Cr(IV)? Cr(III). This is supported by the observation of the optical absorption spectra of Cr(VI) esters, free radicals, CrO(2)(2+) (superoxoCr(III) ion) and oxo-Cr(V) complexes. Cr(IV) cannot be directly detected; however, formation of CrO(2)(2+) provides indirect evidence for the intermediacy of Cr(II/IV). Cr(IV) reacts with Galur much faster than Cr(V) and Cr(VI) do. The analysis of the reaction kinetics via optical absorption spectroscopy shows that the Cr(IV)-Galur reaction rate inversely depends on [H(+)]. Nevertheless, high [H(+)] still does not facilitate accumulation of Cr(IV) in the Cr(VI)-Galur mixture. Cr(VI) and the intermediate Cr(V) react with Galur at comparable rates; therefore the build-up and decay of Cr(V) accompany the decay of Cr(VI). The complete rate laws for the Cr(VI), Cr(V) and Cr(IV)-Galur redox reaction are here derived in detail. Furthermore, the nature of the five-co-ordinated oxo-Cr(V) bischelate complexes formed in Cr(VI)-Galur mixtures at pH 1-5 is investigated using continuous-wave and pulsed electron paramagnetic resonance (EPR) and density functional theory (DFT)."
1290275,Broadway et al. 2010,Determination of the bioaccessibility of chromium in Glasgow soil and the implications for human health risk assessment,"The Unified Bioaccessibility Method (UBM), which simulates the fluids of the human gastrointestinal tract, was used to assess the oral bioaccessibility of Cr in 27 Glasgow soils. These included several contaminated with Cr(VI), the most toxic form of Cr, from the past disposal of chromite ore processing residue (COPR). The extraction was employed in conjunction with the subsequent determination of the bioaccessible Cr by ICP-OES and Cr(VI) by the diphenylcarbazide complexation colorimetric procedure. In addition, Cr(III)-containing species were determined by (i) HPLC-ICP-MS and (ii) ICP-OES analysis of gel electrophoretically separated components of colloidal and dissolved fractions from centrifugal ultrafiltration of extracts. Similar analytical procedures were applied to the determination of Cr and its species in extracts of the &lt;10 ?m fraction of soils subjected to a simulated lung fluid test to assess the inhalation bioaccessibility of Cr. The oral bioaccessibility of Cr was typically greater by a factor of 1.5 in the 'stomach' (pH ~1.2) compared with the 'stomach+intestine' (pH ~6.3) simulation. On average, excluding two COPR-contaminated soil samples, the oral bioaccessibility ('stomach') was 5% of total soil Cr and, overall, similar to the soil Cr(VI) concentration. Chromium(VI) was not detected in the extracts, a consequence of pH- and soil organic matter-mediated reduction in the 'stomach' to Cr(III)-containing species, identified as predominantly Cr(III)-humic complexes. Insertion of oral bioaccessible fraction data into the SNIFFER human health risk assessment model identified site-specific assessment criteria (for residential land without plant uptake) that were exceeded by the soil total Cr (3680 mg kg(-1)) and Cr(VI) (1485 mg kg(-1)) concentration at only the most COPR-Cr(VI)-contaminated location. However, the presence of measurable Cr(VI) in the &lt;10 ?m fraction of the two most highly Cr(VI)-contaminated soils demonstrated that inhalation of Cr(VI)-containing dust remains the most potentially harmful exposure route.","Determination of the bioaccessibility of chromium in Glasgow soil and the implications for human health risk assessment Abs: The Unified Bioaccessibility Method (UBM), which simulates the fluids of the human gastrointestinal tract, was used to assess the oral bioaccessibility of Cr in 27 Glasgow soils. These included several contaminated with Cr(VI), the most toxic form of Cr, from the past disposal of chromite ore processing residue (COPR). The extraction was employed in conjunction with the subsequent determination of the bioaccessible Cr by ICP-OES and Cr(VI) by the diphenylcarbazide complexation colorimetric procedure. In addition, Cr(III)-containing species were determined by (i) HPLC-ICP-MS and (ii) ICP-OES analysis of gel electrophoretically separated components of colloidal and dissolved fractions from centrifugal ultrafiltration of extracts. Similar analytical procedures were applied to the determination of Cr and its species in extracts of the &lt;10 ?m fraction of soils subjected to a simulated lung fluid test to assess the inhalation bioaccessibility of Cr. The oral bioaccessibility of Cr was typically greater by a factor of 1.5 in the 'stomach' (pH ~1.2) compared with the 'stomach+intestine' (pH ~6.3) simulation. On average, excluding two COPR-contaminated soil samples, the oral bioaccessibility ('stomach') was 5% of total soil Cr and, overall, similar to the soil Cr(VI) concentration. Chromium(VI) was not detected in the extracts, a consequence of pH- and soil organic matter-mediated reduction in the 'stomach' to Cr(III)-containing species, identified as predominantly Cr(III)-humic complexes. Insertion of oral bioaccessible fraction data into the SNIFFER human health risk assessment model identified site-specific assessment criteria (for residential land without plant uptake) that were exceeded by the soil total Cr (3680 mg kg(-1)) and Cr(VI) (1485 mg kg(-1)) concentration at only the most COPR-Cr(VI)-contaminated location. However, the presence of measurable Cr(VI) in the &lt;10 ?m fraction of the two most highly Cr(VI)-contaminated soils demonstrated that inhalation of Cr(VI)-containing dust remains the most potentially harmful exposure route."
1290274,Afolaranmi et al. 2011,Effect of chromium and cobalt ions on phase I and phase II enzymatic activities in vitro in freshly isolated rat hepatocytes,"The effect of in vitro exposure to the metal ions (chromium (VI) and cobalt (II)) on phase I and phase II enzymatic activities in freshly isolated rat hepatocytes is reported. Concentrations of metal ions used reflect those reported in the livers of cadavers that had worn metal-on-metal hip implants. To assess the effect of exposure to metal ions on enzymatic activities of phase I metabolic reactions the hydroxylations of testosterone were measured, and the phase II reactions measured were glucuronidation and sulfation. No effect was observed in the formation of the testosterone metabolites measured in the presence of either ion, Cr (VI) inhibited both glucuronidation and sulfation of 7-hydroxycoumarin (7-HC) and 1-naphthol, while Co inhibited only the glucuronidation of 7-HC and 1-naphthol. ATP levels were reduced in freshly isolated rat hepatocytes treated with Cr (VI) compared with control hepatocytes with no metal treatment. Cr (VI) probably inhibits the formation of 3'-phosphoadenosine 5'-phosphosulfate (PAPS), the high energy co-factor of sulfation, by reducing the availability of ATP and also by acting as a substrate analog and competing with sulfate for ATP-sulfurylase. High concentrations of these metal ions in the livers of patients with loose or worn metal implants may act synergistically, and have consequences for the metabolism of xenobiotics.","Effect of chromium and cobalt ions on phase I and phase II enzymatic activities in vitro in freshly isolated rat hepatocytes Abs: The effect of in vitro exposure to the metal ions (chromium (VI) and cobalt (II)) on phase I and phase II enzymatic activities in freshly isolated rat hepatocytes is reported. Concentrations of metal ions used reflect those reported in the livers of cadavers that had worn metal-on-metal hip implants. To assess the effect of exposure to metal ions on enzymatic activities of phase I metabolic reactions the hydroxylations of testosterone were measured, and the phase II reactions measured were glucuronidation and sulfation. No effect was observed in the formation of the testosterone metabolites measured in the presence of either ion, Cr (VI) inhibited both glucuronidation and sulfation of 7-hydroxycoumarin (7-HC) and 1-naphthol, while Co inhibited only the glucuronidation of 7-HC and 1-naphthol. ATP levels were reduced in freshly isolated rat hepatocytes treated with Cr (VI) compared with control hepatocytes with no metal treatment. Cr (VI) probably inhibits the formation of 3'-phosphoadenosine 5'-phosphosulfate (PAPS), the high energy co-factor of sulfation, by reducing the availability of ATP and also by acting as a substrate analog and competing with sulfate for ATP-sulfurylase. High concentrations of these metal ions in the livers of patients with loose or worn metal implants may act synergistically, and have consequences for the metabolism of xenobiotics."
1290272,Asatiani et al. 2011,Chromium (VI) can activate and impair antioxidant defense system,"The changes in glutathione-dependent cycle enzymes and catalase activities under Cr(VI)-induced oxidative stress were investigated in two distinct cell lines: L-41-human epithelial-like cells and HLF-fetal human diploid lung fibroblasts, which differ in tissue origin, proliferation, and antioxidant enzymes activities. The chromium concentrations from 1 to 5 ?M cause nontoxic effects and activate antioxidant enzymes to overcome oxidative stress. In spite of some differences in the endogenous antioxidant activities, both cell lines reveal the same range of toxic concentrations (20-30 ?M). The irreversible inhibition of glutathione-dependent antioxidant enzymes develops under toxic concentrations and serves as a marker of toxicity. The endogenous antioxidant activity influences time-dependent expression of Cr(VI) toxicity and the dynamics of antioxidant enzymes activity under nontoxic conditions. The cell antioxidant defense system is an important marker of the cell adaptive capacity under nontoxic and toxic conditions.","Chromium (VI) can activate and impair antioxidant defense system Abs: The changes in glutathione-dependent cycle enzymes and catalase activities under Cr(VI)-induced oxidative stress were investigated in two distinct cell lines: L-41-human epithelial-like cells and HLF-fetal human diploid lung fibroblasts, which differ in tissue origin, proliferation, and antioxidant enzymes activities. The chromium concentrations from 1 to 5 ?M cause nontoxic effects and activate antioxidant enzymes to overcome oxidative stress. In spite of some differences in the endogenous antioxidant activities, both cell lines reveal the same range of toxic concentrations (20-30 ?M). The irreversible inhibition of glutathione-dependent antioxidant enzymes develops under toxic concentrations and serves as a marker of toxicity. The endogenous antioxidant activity influences time-dependent expression of Cr(VI) toxicity and the dynamics of antioxidant enzymes activity under nontoxic conditions. The cell antioxidant defense system is an important marker of the cell adaptive capacity under nontoxic and toxic conditions."
1290271,Oliveira and  Oliveira-Brett 2010,In situ evaluation of chromium-DNA damage using a DNA-electrochemical biosensor,"The in situ evaluation of the direct interaction of chromium species with double-stranded DNA (dsDNA) was studied using differential pulse voltammetry at a glassy carbon electrode. The DNA damage was electrochemically detected following the changes in the oxidation peaks of guanosine and adenosine bases. The results obtained revealed the interaction with dsDNA of the Cr(IV) and Cr(V) reactive intermediates of Cr(III) oxidation by O(2) dissolved in the solution bound to dsDNA. This interaction leads to different modifications and causes oxidative damage in the B-DNA structure. Using polyhomonucleotides of guanine and adenine, it was shown that the interaction between reactive intermediates Cr(IV) and Cr(V)-DNA causes oxidative damage and preferentially takes place at guanine-rich segments, leading to the formation of 8-oxoguanine, the oxidation product of guanine residues and a biomarker of DNA oxidative damage. The interaction of Cr(VI) with dsDNA causes breaking of hydrogen bonds, conformational changes, and unfolding of the double helix, which enables easier access of other oxidative agents to interact with DNA, and the occurrence of oxidative damage to DNA.","In situ evaluation of chromium-DNA damage using a DNA-electrochemical biosensor Abs: The in situ evaluation of the direct interaction of chromium species with double-stranded DNA (dsDNA) was studied using differential pulse voltammetry at a glassy carbon electrode. The DNA damage was electrochemically detected following the changes in the oxidation peaks of guanosine and adenosine bases. The results obtained revealed the interaction with dsDNA of the Cr(IV) and Cr(V) reactive intermediates of Cr(III) oxidation by O(2) dissolved in the solution bound to dsDNA. This interaction leads to different modifications and causes oxidative damage in the B-DNA structure. Using polyhomonucleotides of guanine and adenine, it was shown that the interaction between reactive intermediates Cr(IV) and Cr(V)-DNA causes oxidative damage and preferentially takes place at guanine-rich segments, leading to the formation of 8-oxoguanine, the oxidation product of guanine residues and a biomarker of DNA oxidative damage. The interaction of Cr(VI) with dsDNA causes breaking of hydrogen bonds, conformational changes, and unfolding of the double helix, which enables easier access of other oxidative agents to interact with DNA, and the occurrence of oxidative damage to DNA."
1290270,Ning and  Grant 1999,Chromium (VI)-induced cytotoxicity to osteoblast-derived cells,"Chromium is well recognized as a carcinogen, and there are concerns about local and systemic cytotoxicity and carcinogenicity during the use of chromium-containing alloys for orthopaedic implants. We have investigated the cytotoxicity of Cr VI in immortalized rat osteoblast cells in vitro using alkaline phosphatase (ALP) activity as an index of toxicity. Cr VI caused a concentration-dependent decrease in ALP activity, thought to be mediated by intracellular reduction to Cr III. The role of several antioxidant vitamins, reduced glutathione (GSH) and DT-diaphorase in the reduction of Cr VI was investigated. The toxic response to Cr VI was partially prevented by treating the cells with ascorbic acid. In contrast, riboflavin and alpha-tocopherol did not alter the response. Ascorbic acid is thought to reduce Cr VI to Cr III extracellularly. This protects the cells because they are relatively impermeable to Cr III. Treatment of cells with dicoumarol, an inhibitor of DT-diaphorase activity, also decreased the toxicity of Cr VI, suggesting that this enzyme is involved in the intracellular reduction of the metal. GSH was not depleted during the metabolism of Cr VI and this was probably due to the activity of glutathione reductase which acts to recycle oxidized glutathione. However, depletion of intracellular GSH by buthionine sulfoximine increased the toxicity of Cr VI at early time points (after 1.5 and 3hr exposure). GSH and Cr VI therefore interact in the osteoblasts, and this may be through formation of a conjugate and/or by detoxification of reactive intermediates formed during redox cycling of the chromium.","Chromium (VI)-induced cytotoxicity to osteoblast-derived cells Abs: Chromium is well recognized as a carcinogen, and there are concerns about local and systemic cytotoxicity and carcinogenicity during the use of chromium-containing alloys for orthopaedic implants. We have investigated the cytotoxicity of Cr VI in immortalized rat osteoblast cells in vitro using alkaline phosphatase (ALP) activity as an index of toxicity. Cr VI caused a concentration-dependent decrease in ALP activity, thought to be mediated by intracellular reduction to Cr III. The role of several antioxidant vitamins, reduced glutathione (GSH) and DT-diaphorase in the reduction of Cr VI was investigated. The toxic response to Cr VI was partially prevented by treating the cells with ascorbic acid. In contrast, riboflavin and alpha-tocopherol did not alter the response. Ascorbic acid is thought to reduce Cr VI to Cr III extracellularly. This protects the cells because they are relatively impermeable to Cr III. Treatment of cells with dicoumarol, an inhibitor of DT-diaphorase activity, also decreased the toxicity of Cr VI, suggesting that this enzyme is involved in the intracellular reduction of the metal. GSH was not depleted during the metabolism of Cr VI and this was probably due to the activity of glutathione reductase which acts to recycle oxidized glutathione. However, depletion of intracellular GSH by buthionine sulfoximine increased the toxicity of Cr VI at early time points (after 1.5 and 3hr exposure). GSH and Cr VI therefore interact in the osteoblasts, and this may be through formation of a conjugate and/or by detoxification of reactive intermediates formed during redox cycling of the chromium."
1290268,Levina et al. 2010,Formation and reactivity of chromium(V)-thiolato complexes: a model for the intracellular reactions of carcinogenic chromium(VI) with biological thiols,"The nature of the long-lived EPR-active Cr(V) species observed in cells and biological fluids exposed to carcinogenic Cr(VI) has been definitively assigned from detailed kinetic and spectroscopic analyses of a model reaction of Cr(VI) with p-bromobenzenethiol (RSH) in the presence or absence of cyclic 1,2-diols (LH(2)) in aprotic or mixed solvents. The first definitive structures for Cr(V) complexes with a monodentate thiolato ligand, [Cr(V)O(SR)(4)](-) (g(iso) = 1.9960, A(iso) = 14.7 x 10(-4) cm(-1)), [Cr(V)OL(SR)(2)](-) (g(iso) = 1.9854, A(iso) = (15.8-16.2) x 10(-4) cm(-1)) and [Cr(V)(O)(2)(SR)(2)](-) (g(iso) = 1.9828, A(iso) = 6.8 x 10(-4) cm(-1)) were assigned by EPR spectroscopy and electrospray mass spectrometry. The unusually low A(iso) ((53)Cr) value for the latter species is consistent with its rare four-coordinate, bis-oxido structure. The [Cr(V)OL(SR)(2)](-) species are responsible for the transient g(iso) approximately 1.986 EPR signals observed in living cells and animals treated with Cr(VI) (where RSH and LH(2) are biological thiols and 1,2-diols, respectively). For the first time, concentrations of Cr(V) intermediates formed during the reduction of Cr(VI) were determined by quantitative EPR spectroscopy, and a detailed reaction mechanism was proposed on the basis of stochastic simulations of the kinetic curves for Cr(V) species. A key feature of the proposed mechanism is the regeneration of Cr(V) species in the presence of Cr(VI) through the formation of organic free radicals, followed by the rapid reactions of the formed radicals with Cr(VI). The concentration of Cr(V) grows rapidly at the beginning of the reaction, reaches a steady-state level, and then drops sharply once Cr(VI) is spent. Similar mechanisms are likely to operate during the reduction of Cr(VI) in biological environment rich in reactive C-H bonds, including the oxidative DNA damage by Cr(V) intermediates.","Formation and reactivity of chromium(V)-thiolato complexes: a model for the intracellular reactions of carcinogenic chromium(VI) with biological thiols Abs: The nature of the long-lived EPR-active Cr(V) species observed in cells and biological fluids exposed to carcinogenic Cr(VI) has been definitively assigned from detailed kinetic and spectroscopic analyses of a model reaction of Cr(VI) with p-bromobenzenethiol (RSH) in the presence or absence of cyclic 1,2-diols (LH(2)) in aprotic or mixed solvents. The first definitive structures for Cr(V) complexes with a monodentate thiolato ligand, [Cr(V)O(SR)(4)](-) (g(iso) = 1.9960, A(iso) = 14.7 x 10(-4) cm(-1)), [Cr(V)OL(SR)(2)](-) (g(iso) = 1.9854, A(iso) = (15.8-16.2) x 10(-4) cm(-1)) and [Cr(V)(O)(2)(SR)(2)](-) (g(iso) = 1.9828, A(iso) = 6.8 x 10(-4) cm(-1)) were assigned by EPR spectroscopy and electrospray mass spectrometry. The unusually low A(iso) ((53)Cr) value for the latter species is consistent with its rare four-coordinate, bis-oxido structure. The [Cr(V)OL(SR)(2)](-) species are responsible for the transient g(iso) approximately 1.986 EPR signals observed in living cells and animals treated with Cr(VI) (where RSH and LH(2) are biological thiols and 1,2-diols, respectively). For the first time, concentrations of Cr(V) intermediates formed during the reduction of Cr(VI) were determined by quantitative EPR spectroscopy, and a detailed reaction mechanism was proposed on the basis of stochastic simulations of the kinetic curves for Cr(V) species. A key feature of the proposed mechanism is the regeneration of Cr(V) species in the presence of Cr(VI) through the formation of organic free radicals, followed by the rapid reactions of the formed radicals with Cr(VI). The concentration of Cr(V) grows rapidly at the beginning of the reaction, reaches a steady-state level, and then drops sharply once Cr(VI) is spent. Similar mechanisms are likely to operate during the reduction of Cr(VI) in biological environment rich in reactive C-H bonds, including the oxidative DNA damage by Cr(V) intermediates."
1290267,Figgitt et al. 2010,The genotoxicity of physiological concentrations of chromium (Cr(III) and Cr(VI)) and cobalt (Co(II)): an in vitro study,"Humans are exposed to chromium and cobalt in industry, from the environment and after joint replacement surgery from the CoCr alloy in the implant. In this study we have investigated whether Cr(III), Cr(VI), Co(II) and Cr in combination with Co could induce chromosome aberrations in human fibroblasts in vitro at the same concentrations that have been found in the peripheral blood of exposed humans. We used 24 colour M-FISH as a sensitive way to detect translocations and aneuploidy and examined the effects of a 24-h exposure and its consequences up to 30 days after the exposure in order to record genomic instability and/or repair. At these physiological doses the metals induced predominantly numerical rather than structural aberrations. Co was the least reactive and Cr(VI) especially in combination with Co the most. All metals at the highest physiological doses caused simple (gain or loss of 3 or less chromosomes) and complex (more than 49 chromosomes) aneuploidy. All metals at the lowest physiological dose caused a significant increase of total aberrations. Cr(VI) was much more effective than Cr(III) in causing chromosome fragments, which were only induced at the highest doses. There was a slow resolution of aneuploidy with time after exposure. This involved a reduction in the proportion of aneuploid cells and a reduction of the number of chromosomes within cells showing complex aneuploidy. We conclude that these metal ions can cause chromosome aberrations at physiological concentrations and that their main effect is aneugenic.","The genotoxicity of physiological concentrations of chromium (Cr(III) and Cr(VI)) and cobalt (Co(II)): an in vitro study Abs: Humans are exposed to chromium and cobalt in industry, from the environment and after joint replacement surgery from the CoCr alloy in the implant. In this study we have investigated whether Cr(III), Cr(VI), Co(II) and Cr in combination with Co could induce chromosome aberrations in human fibroblasts in vitro at the same concentrations that have been found in the peripheral blood of exposed humans. We used 24 colour M-FISH as a sensitive way to detect translocations and aneuploidy and examined the effects of a 24-h exposure and its consequences up to 30 days after the exposure in order to record genomic instability and/or repair. At these physiological doses the metals induced predominantly numerical rather than structural aberrations. Co was the least reactive and Cr(VI) especially in combination with Co the most. All metals at the highest physiological doses caused simple (gain or loss of 3 or less chromosomes) and complex (more than 49 chromosomes) aneuploidy. All metals at the lowest physiological dose caused a significant increase of total aberrations. Cr(VI) was much more effective than Cr(III) in causing chromosome fragments, which were only induced at the highest doses. There was a slow resolution of aneuploidy with time after exposure. This involved a reduction in the proportion of aneuploid cells and a reduction of the number of chromosomes within cells showing complex aneuploidy. We conclude that these metal ions can cause chromosome aberrations at physiological concentrations and that their main effect is aneugenic."
1290265,Chandra et al. 2010,Vitamin E-supplementation protect chromium (VI)-induced spermatogenic and steroidogenic disorders in testicular tissues of rats,"Excess chromium (Cr) exposure is associated with various pathological conditions including reproductive dysfunction. Generation of oxidative stress is one of the plausible mechanisms behind Cr induced cellular deteriorations. The efficacy of vitamin E to combat Cr induced oxidative damage in adult rat testis has investigated in the current study. Adult male rats exposed to hexavalent Cr (intraperitoneal injection with 0.4 mg K(2)Cr(2)O(7)/ kg bw/day) for 26 days resulted in decreased accessory sex organs weight compared to controls. Development of oxidative stress in testis was evidenced by increased lipid peroxidation along with decreased superoxide dismutase (SOD) and catalase activities than control animals. Marked reduction in the activities of testicular steroidogenic enzymes; Delta(5)3beta-hydroxysteroid dehydrogenase (HSD), 17beta-HSD, serum testosterone and Leutinizing Hormone (LH) levels were observed. However significant increase in serum Follicle Stimulating Hormone (FSH) level was observed with Cr treated group. Histological evaluation of testis revealed degeneration of stage VII spermatogenic cycle along with decrease in epithelial cell height in epididymis and seminiferous tubules; number of different germ cells per seminiferous tubule and seminiferous tubular diameter reduced after Cr exposure. Simultaneous oral supplementation of vitamin E (50mg/kg bw/day) in Cr exposed rats showed less oxidative damage and restored the otherwise altered testicular activities. Epididymal sperm number was also restored in vitamin E-supplemented group than Cr induced rats. This study implicates vitamin E as a possible protective agent against Cr induced spermatogenic and steroidogenic alteration.","Vitamin E-supplementation protect chromium (VI)-induced spermatogenic and steroidogenic disorders in testicular tissues of rats Abs: Excess chromium (Cr) exposure is associated with various pathological conditions including reproductive dysfunction. Generation of oxidative stress is one of the plausible mechanisms behind Cr induced cellular deteriorations. The efficacy of vitamin E to combat Cr induced oxidative damage in adult rat testis has investigated in the current study. Adult male rats exposed to hexavalent Cr (intraperitoneal injection with 0.4 mg K(2)Cr(2)O(7)/ kg bw/day) for 26 days resulted in decreased accessory sex organs weight compared to controls. Development of oxidative stress in testis was evidenced by increased lipid peroxidation along with decreased superoxide dismutase (SOD) and catalase activities than control animals. Marked reduction in the activities of testicular steroidogenic enzymes; Delta(5)3beta-hydroxysteroid dehydrogenase (HSD), 17beta-HSD, serum testosterone and Leutinizing Hormone (LH) levels were observed. However significant increase in serum Follicle Stimulating Hormone (FSH) level was observed with Cr treated group. Histological evaluation of testis revealed degeneration of stage VII spermatogenic cycle along with decrease in epithelial cell height in epididymis and seminiferous tubules; number of different germ cells per seminiferous tubule and seminiferous tubular diameter reduced after Cr exposure. Simultaneous oral supplementation of vitamin E (50mg/kg bw/day) in Cr exposed rats showed less oxidative damage and restored the otherwise altered testicular activities. Epididymal sperm number was also restored in vitamin E-supplemented group than Cr induced rats. This study implicates vitamin E as a possible protective agent against Cr induced spermatogenic and steroidogenic alteration."
1290263,Mccarroll et al. 2010,An evaluation of the mode of action framework for mutagenic carcinogens case study II: chromium (VI),"In response to the 2005 revised U.S Environmental Protection Agency's (EPA) Cancer Guidelines, a strategy is being developed to include all mutagenicity and other genotoxicity data with additional information to determine whether the initiating step in carcinogenesis is through a mutagenic mode of action (MOA). This information is necessary to decide if age-dependent adjustment factors (ADAFs) should be applied to the risk assessment. Chromium (VI) [Cr (VI)], a carcinogen in animals and humans via inhalation, was reassessed by the National Toxicology Program (NTP) in 2-year drinking water studies in rodents. From these data, NTP concluded that the results with Cr (VI) showed clear evidence of carcinogenicity in male and female mice and rats. Cr (VI) is also mutagenic, in numerous in vitro assays, in animals (mice and rats) and in humans. Accordingly, Cr (VI) was processed through the MOA framework; postulated key steps in tumor formation were interaction of DNA with Cr (VI) and reduction to Cr (III), mutagenesis, cell proliferation, and tumor formation. Within the timeframe and tumorigenic dose range for early events, genetic changes in mice (single/double-stranded DNA breaks) commence within 24 hr. Mechanistic evidence was also found for oxidative damage and DNA adduct formation contributing to the tumor response. The weight of evidence supports the plausibility that Cr (VI) may act through a mutagenic MOA. Therefore, the Cancer Guidelines recommend a linear extrapolation for the oral risk assessment. Cr (VI) also induces germ cell mutagenicity and causes DNA deletions in developing embryos; thus, it is recommended that the ADAFs be applied.","An evaluation of the mode of action framework for mutagenic carcinogens case study II: chromium (VI) Abs: In response to the 2005 revised U.S Environmental Protection Agency's (EPA) Cancer Guidelines, a strategy is being developed to include all mutagenicity and other genotoxicity data with additional information to determine whether the initiating step in carcinogenesis is through a mutagenic mode of action (MOA). This information is necessary to decide if age-dependent adjustment factors (ADAFs) should be applied to the risk assessment. Chromium (VI) [Cr (VI)], a carcinogen in animals and humans via inhalation, was reassessed by the National Toxicology Program (NTP) in 2-year drinking water studies in rodents. From these data, NTP concluded that the results with Cr (VI) showed clear evidence of carcinogenicity in male and female mice and rats. Cr (VI) is also mutagenic, in numerous in vitro assays, in animals (mice and rats) and in humans. Accordingly, Cr (VI) was processed through the MOA framework; postulated key steps in tumor formation were interaction of DNA with Cr (VI) and reduction to Cr (III), mutagenesis, cell proliferation, and tumor formation. Within the timeframe and tumorigenic dose range for early events, genetic changes in mice (single/double-stranded DNA breaks) commence within 24 hr. Mechanistic evidence was also found for oxidative damage and DNA adduct formation contributing to the tumor response. The weight of evidence supports the plausibility that Cr (VI) may act through a mutagenic MOA. Therefore, the Cancer Guidelines recommend a linear extrapolation for the oral risk assessment. Cr (VI) also induces germ cell mutagenicity and causes DNA deletions in developing embryos; thus, it is recommended that the ADAFs be applied."
1290262,Zecevic et al. 2009,WRN helicase promotes repair of DNA double-strand breaks caused by aberrant mismatch repair of chromium-DNA adducts,"Recent studies in yeast have found that processing of DNA double-strand breaks (DSB) for recombination repair involves Sgs1 helicase. Human cells have five Sgs1 homologues with unknown selectivity and significance for repair of different DSB types. Here we examined the importance of WRN helicase in repair of G(2)-specific DSB caused by abnormal mismatch repair (MMR) of ternary Cr-DNA adducts. We found that Cr(VI) induced a rapid dispersal of WRN from the nucleolus resulting in its prolonged retention in the nucleoplasm. The loss of MSH2 or MLH1 MMR proteins abolished the long-term but not the initial WRN relocalization. WRN-deficient fibroblasts were hypersensitive to Cr(VI)-induced clonogenic death and contained high levels of persistent DSB detected by gamma-H2AX/53BP1 foci and pulsed-field gel electrophoresis. WRN was involved in recombination repair of Cr-induced DNA damage, as evidenced by WRN-RAD51 colocalization and defective formation of RAD51 foci in the absence of WRN. The accumulation of unrepaired DSB in WRN-depleted cells was rescued by the inactivation of MMR, indicating that MMR-generated DSB were a key substrate for WRN action in Cr(VI)-treated cells. Competition for the limited amounts of WRN in primary cells between G(2) processes of telomere rebuilding and recombinational repair is expected to increase persistence of Cr-induced DSB and may cause telomeric abnormalities in tissues of chronically chromate-exposed workers. Our work provides the first demonstration of the major importance of WRN in repair of a specific class of DSB in human cells.","WRN helicase promotes repair of DNA double-strand breaks caused by aberrant mismatch repair of chromium-DNA adducts Abs: Recent studies in yeast have found that processing of DNA double-strand breaks (DSB) for recombination repair involves Sgs1 helicase. Human cells have five Sgs1 homologues with unknown selectivity and significance for repair of different DSB types. Here we examined the importance of WRN helicase in repair of G(2)-specific DSB caused by abnormal mismatch repair (MMR) of ternary Cr-DNA adducts. We found that Cr(VI) induced a rapid dispersal of WRN from the nucleolus resulting in its prolonged retention in the nucleoplasm. The loss of MSH2 or MLH1 MMR proteins abolished the long-term but not the initial WRN relocalization. WRN-deficient fibroblasts were hypersensitive to Cr(VI)-induced clonogenic death and contained high levels of persistent DSB detected by gamma-H2AX/53BP1 foci and pulsed-field gel electrophoresis. WRN was involved in recombination repair of Cr-induced DNA damage, as evidenced by WRN-RAD51 colocalization and defective formation of RAD51 foci in the absence of WRN. The accumulation of unrepaired DSB in WRN-depleted cells was rescued by the inactivation of MMR, indicating that MMR-generated DSB were a key substrate for WRN action in Cr(VI)-treated cells. Competition for the limited amounts of WRN in primary cells between G(2) processes of telomere rebuilding and recombinational repair is expected to increase persistence of Cr-induced DSB and may cause telomeric abnormalities in tissues of chronically chromate-exposed workers. Our work provides the first demonstration of the major importance of WRN in repair of a specific class of DSB in human cells."
1290261,Bae et al. 2009,Enhanced clonogenic survival induced by protein tyrosine phosphatase (PTP) inhibition after Cr(VI) exposure is mediated by c-Raf and Ras activity,"Our recent studies showed that maintenance of protein tyrosine phosphorylation by PTP inhibition enhanced cell growth, clonogenic survival, and mutagenesis after a single low-level Cr(VI) exposure, thereby suggesting that tyrosine phosphorylation-dependent signaling may govern inappropriate survival in human lung fibroblasts (HLFs). Our goal is to identify specific phospho-tyrosine regulator(s)/ downstream effectors involved in enhanced survival after Cr(VI) exposure and PTP inhibition. Phosphotyrosine profiling array showed that PTP inhibition following Cr(VI) exposure increased tyrosine phosphorylation of specific proteins, such as FGR and ABL, which are upstream regulators of both Erk and Akt pathways. To explore the roles of these pathways in the PTP-induced increase in clonogenic survival after Cr(VI) exposure, we examined the effect of combined Akt1 and Erk1/2 knockdown via siRNA technology. Akt1 and/or Erk1/2 silencing had no effect on the PTP inhibitor-induced increase in survival following Cr(VI) exposure, suggesting the presence of non-Akt/non-Erk-mediated survival signaling. Interestingly, geldanamycin, an HSP90 inhibitor and non-specific Raf inhibitor, abrogated the PTP inhibitor-mediated increase in survival following Cr(VI) exposure and abolished the expression/activity of c-Raf and activity of Mek. These findings prompted us to explore upstream regulators of Erk, i.e., Ras, c-Raf and Mek for their potential roles in clonogenic survival. GW5074, a specific c-Raf kinase inhibitor did not alter the effect of the PTP inhibitor but decreased Cr(VI)-mediated clonogenic lethality, potentially though Mek hyperactivation. A genetic approach with a c/a Mek1 mutant also showed that Mek activity was not directly associated with the PTP inhibitor effect. Finally, a genetic approach with d/n or c/a Ras and c-Raf mutants, showed that Ras and c-Raf activities play a substantive role in enhancing clonogenic survival by PTP inhibition following Cr(VI) insult. In conclusion, these studies highlight a novel pro-survival mechanism for clonogenic survival in the face of genotoxic stress in the presence of PTP inhibition via an Erk/Mek-independent and Ras/c-Raf-dependent regulation in normal human lung fibroblasts.","Enhanced clonogenic survival induced by protein tyrosine phosphatase (PTP) inhibition after Cr(VI) exposure is mediated by c-Raf and Ras activity Abs: Our recent studies showed that maintenance of protein tyrosine phosphorylation by PTP inhibition enhanced cell growth, clonogenic survival, and mutagenesis after a single low-level Cr(VI) exposure, thereby suggesting that tyrosine phosphorylation-dependent signaling may govern inappropriate survival in human lung fibroblasts (HLFs). Our goal is to identify specific phospho-tyrosine regulator(s)/ downstream effectors involved in enhanced survival after Cr(VI) exposure and PTP inhibition. Phosphotyrosine profiling array showed that PTP inhibition following Cr(VI) exposure increased tyrosine phosphorylation of specific proteins, such as FGR and ABL, which are upstream regulators of both Erk and Akt pathways. To explore the roles of these pathways in the PTP-induced increase in clonogenic survival after Cr(VI) exposure, we examined the effect of combined Akt1 and Erk1/2 knockdown via siRNA technology. Akt1 and/or Erk1/2 silencing had no effect on the PTP inhibitor-induced increase in survival following Cr(VI) exposure, suggesting the presence of non-Akt/non-Erk-mediated survival signaling. Interestingly, geldanamycin, an HSP90 inhibitor and non-specific Raf inhibitor, abrogated the PTP inhibitor-mediated increase in survival following Cr(VI) exposure and abolished the expression/activity of c-Raf and activity of Mek. These findings prompted us to explore upstream regulators of Erk, i.e., Ras, c-Raf and Mek for their potential roles in clonogenic survival. GW5074, a specific c-Raf kinase inhibitor did not alter the effect of the PTP inhibitor but decreased Cr(VI)-mediated clonogenic lethality, potentially though Mek hyperactivation. A genetic approach with a c/a Mek1 mutant also showed that Mek activity was not directly associated with the PTP inhibitor effect. Finally, a genetic approach with d/n or c/a Ras and c-Raf mutants, showed that Ras and c-Raf activities play a substantive role in enhancing clonogenic survival by PTP inhibition following Cr(VI) insult. In conclusion, these studies highlight a novel pro-survival mechanism for clonogenic survival in the face of genotoxic stress in the presence of PTP inhibition via an Erk/Mek-independent and Ras/c-Raf-dependent regulation in normal human lung fibroblasts."
1290260,Tkaczyk et al. 2009,The molecular structure of complexes formed by chromium or cobalt ions in simulated physiological fluids,"It is well recognized that workers in mines and manufacturers of hard metals in contact with metal ions have increased risk of cancer. However, the various chemical forms of these ions in living organisms are not well characterized, and little is known of how they interact with biological environments. Here, we sought to elucidate the molecular structures formed by cobalt (Co) and chromium (Cr) ions in simulated biological fluids. Transmission electron microscopy observations revealed that Cr(III) formed nanoscale complexes which precipitate in both RPMI 1640 and DMEM high glucose media. However, no complexes were observed with Co(II) and Cr(VI). Energy-dispersive X-ray analysis, elemental analysis, and Fourier transform infrared (FT-IR) spectroscopy indicated that Cr(III) ions act as chelating entities between PO(4) groups, amino acids, and calcium. Although the exact nature of the bonds remains to be investigated, the presence of PO(4) may favor the formation of low energy hydrogen bonds. Interestingly, the nature of amino acids varied in Cr(III) complexes formed in RPMI 1640 compared to those formed in DMEM high glucose. The absence of sulphur in the elemental analysis spectrum suggested that methionine and cystine, two amino acids containing sulphur, are not involved in the formation of Cr(III) complexes. Thus, the lower toxicity of Cr(III) compared to Co(II) and Cr(VI) may be related to the formation of these chemical complexes. These results may bring some insight in understanding the relationship between toxicity and the chelating capabilities of various metal ions in vitro and in vivo.","The molecular structure of complexes formed by chromium or cobalt ions in simulated physiological fluids Abs: It is well recognized that workers in mines and manufacturers of hard metals in contact with metal ions have increased risk of cancer. However, the various chemical forms of these ions in living organisms are not well characterized, and little is known of how they interact with biological environments. Here, we sought to elucidate the molecular structures formed by cobalt (Co) and chromium (Cr) ions in simulated biological fluids. Transmission electron microscopy observations revealed that Cr(III) formed nanoscale complexes which precipitate in both RPMI 1640 and DMEM high glucose media. However, no complexes were observed with Co(II) and Cr(VI). Energy-dispersive X-ray analysis, elemental analysis, and Fourier transform infrared (FT-IR) spectroscopy indicated that Cr(III) ions act as chelating entities between PO(4) groups, amino acids, and calcium. Although the exact nature of the bonds remains to be investigated, the presence of PO(4) may favor the formation of low energy hydrogen bonds. Interestingly, the nature of amino acids varied in Cr(III) complexes formed in RPMI 1640 compared to those formed in DMEM high glucose. The absence of sulphur in the elemental analysis spectrum suggested that methionine and cystine, two amino acids containing sulphur, are not involved in the formation of Cr(III) complexes. Thus, the lower toxicity of Cr(III) compared to Co(II) and Cr(VI) may be related to the formation of these chemical complexes. These results may bring some insight in understanding the relationship between toxicity and the chelating capabilities of various metal ions in vitro and in vivo."
1290259,Raja and  Nair 2008,Chromium(III) complexes inhibit transcription factors binding to DNA and associated gene expression,"Role of chromium(III) in biological systems is controversial and no significant conclusions can be arrived with the available data. Chromium(VI) enters in to the cell readily and gets reduced to form stable chromium(III) complexes. Chromium(III) complexes react slowly and were considered non-toxic. Recent studies suggest that chromium(III) indeed produce damage to cellular organelle, DNA and proteins and can be lethal to organisms and their offspring. Several chromium(III) complexes synthesized are shown to interact with DNA and bring changes in the conformation of DNA and proteins. In this work, effects of these interactions in the vital process like transcription have been studied. Three Cr(III) complexes with varied ligand environment, ionic character and charge have been chosen for the study to evaluate their ability to interrupt the binding of two different transcription factors Sp1 and TFIID, with their consensus sequences and interruption of the transcription process. Of the three complexes tested [Cr(salen)(H(2)O)(2)](+) is the most efficient inhibitor of transcription factors-DNA (TF-DNA) complex formation and transcription. Inhibition of TF-DNA complex formation and transcription by this complex is concentration-dependent. [Cr(pic)(3)] does not inhibit both TF-DNA complex formation and transcription. [Cr(ttpy)(2)](+3) inhibits TF-DNA complex formation at higher concentrations but does not inhibit transcription even at very high concentrations compared to that of [Cr(salen)(H(2)O)(2)](+). Results of these studies suggest that chromium(III) complexes, though less reactive can still interfere in the important biological process and this interactions are determined by the ligand environment around the complex.","Chromium(III) complexes inhibit transcription factors binding to DNA and associated gene expression Abs: Role of chromium(III) in biological systems is controversial and no significant conclusions can be arrived with the available data. Chromium(VI) enters in to the cell readily and gets reduced to form stable chromium(III) complexes. Chromium(III) complexes react slowly and were considered non-toxic. Recent studies suggest that chromium(III) indeed produce damage to cellular organelle, DNA and proteins and can be lethal to organisms and their offspring. Several chromium(III) complexes synthesized are shown to interact with DNA and bring changes in the conformation of DNA and proteins. In this work, effects of these interactions in the vital process like transcription have been studied. Three Cr(III) complexes with varied ligand environment, ionic character and charge have been chosen for the study to evaluate their ability to interrupt the binding of two different transcription factors Sp1 and TFIID, with their consensus sequences and interruption of the transcription process. Of the three complexes tested [Cr(salen)(H(2)O)(2)](+) is the most efficient inhibitor of transcription factors-DNA (TF-DNA) complex formation and transcription. Inhibition of TF-DNA complex formation and transcription by this complex is concentration-dependent. [Cr(pic)(3)] does not inhibit both TF-DNA complex formation and transcription. [Cr(ttpy)(2)](+3) inhibits TF-DNA complex formation at higher concentrations but does not inhibit transcription even at very high concentrations compared to that of [Cr(salen)(H(2)O)(2)](+). Results of these studies suggest that chromium(III) complexes, though less reactive can still interfere in the important biological process and this interactions are determined by the ligand environment around the complex."
1290257,Lei et al. 2008,Proteomic analysis of chromium cytotoxicity in cultured rat lung epithelial cells,"Chromium (Cr) has been widely used in industry for more than one century. Exposure to hexavalent Cr compounds is strongly associated with increasing risk of lung cancer. Extensive researches at DNA level indicated that generation of ROS from the reduction of Cr(VI) leading to DNA damage is the major cause of the toxicity and carcinogenicity of Cr(VI). The present study in cellular and protein levels confirmed that Cr(VI) induced apoptosis of lung epithelial cells (LEC) via ROS generation. To view the differentially expressed proteins in the process of Cr(VI) reduction, subcellular proteomics was applied and allowed the identification of more than 30 proteins with expression alteration. Most of those proteins are correlated with ROS-elicited responses, which were further validated by Western blotting analysis, induction of p53 pathway and antioxidative treatment. The current findings provided additional evidence in protein level to support the claim that ROS generated during the process of Cr(VI) reduction are involved in the Cr(VI)-induced toxicity and carcinogenesis.","Proteomic analysis of chromium cytotoxicity in cultured rat lung epithelial cells Abs: Chromium (Cr) has been widely used in industry for more than one century. Exposure to hexavalent Cr compounds is strongly associated with increasing risk of lung cancer. Extensive researches at DNA level indicated that generation of ROS from the reduction of Cr(VI) leading to DNA damage is the major cause of the toxicity and carcinogenicity of Cr(VI). The present study in cellular and protein levels confirmed that Cr(VI) induced apoptosis of lung epithelial cells (LEC) via ROS generation. To view the differentially expressed proteins in the process of Cr(VI) reduction, subcellular proteomics was applied and allowed the identification of more than 30 proteins with expression alteration. Most of those proteins are correlated with ROS-elicited responses, which were further validated by Western blotting analysis, induction of p53 pathway and antioxidative treatment. The current findings provided additional evidence in protein level to support the claim that ROS generated during the process of Cr(VI) reduction are involved in the Cr(VI)-induced toxicity and carcinogenesis."
1290256,Yao et al. 2008,Oxidative stress and chromium(VI) carcinogenesis,"Cr(VI)-containing compounds are known carcinogens that are present in industrial settings and in the environment. The biological mechanisms responsible for the initiation and pregression of diseases resulting from exposure to Cr(VI) are not fully understood. In the last two decades, there has been increasing evidence of the correlation between Cr(VI)-induced generation of reactive oxygen species and carcinogenic actions. This article summarizes the current literature on Cr(VI)-induced generation in various chemical and biological systems. This article also covers the relationship between Cr(VI)-induced oxidative stress and activation of transcription factors NF-kappaB, AP-1, p53, and hypoxia-inducible factor 1, regulation of cell cycle, and induction of apoptosis.","Oxidative stress and chromium(VI) carcinogenesis Abs: Cr(VI)-containing compounds are known carcinogens that are present in industrial settings and in the environment. The biological mechanisms responsible for the initiation and pregression of diseases resulting from exposure to Cr(VI) are not fully understood. In the last two decades, there has been increasing evidence of the correlation between Cr(VI)-induced generation of reactive oxygen species and carcinogenic actions. This article summarizes the current literature on Cr(VI)-induced generation in various chemical and biological systems. This article also covers the relationship between Cr(VI)-induced oxidative stress and activation of transcription factors NF-kappaB, AP-1, p53, and hypoxia-inducible factor 1, regulation of cell cycle, and induction of apoptosis."
1290255,Gunaratnam and  Grant 2008,"Cr (VI) inhibits DNA, RNA and protein syntheses in hepatocytes: involvement of glutathione reductase, reduced glutathione and DT-diaphorase","In patients with orthopaedic implants, metallic particles have been shown to be disseminated widely throughout the body, particularly in the liver, spleen and lymph nodes. Levels of metal particles and ions in distant organs were highest in patients with loose, corroded prostheses, and when stainless steel and cobalt chrome alloy corrode, chromium is released predominantly as Cr (VI), a toxic ion. This manuscript investigates the interaction of Cr (VI) with liver cells in terms of inhibition of macromolecular synthesis, and the contribution of reduced glutathione (GSH), DT-diaphorase and glutathione reductase (GRd) to the toxicity of Cr (VI). Cr (VI) caused concentration dependent inhibition of protein, DNA and RNA synthesis in hepatocytes. GRd and to a lesser extent DT-diaphorase activities were involved in the generation of toxic intermediates. GRd activity was markedly inhibited during the reduction of Cr (VI), and GSH levels decreased. The concentrations of Cr (VI) found to inhibit macromolecular syntheses in this study are clinically relevant: it is therefore important to develop implants with minimum wear potential.","Cr (VI) inhibits DNA, RNA and protein syntheses in hepatocytes: involvement of glutathione reductase, reduced glutathione and DT-diaphorase Abs: In patients with orthopaedic implants, metallic particles have been shown to be disseminated widely throughout the body, particularly in the liver, spleen and lymph nodes. Levels of metal particles and ions in distant organs were highest in patients with loose, corroded prostheses, and when stainless steel and cobalt chrome alloy corrode, chromium is released predominantly as Cr (VI), a toxic ion. This manuscript investigates the interaction of Cr (VI) with liver cells in terms of inhibition of macromolecular synthesis, and the contribution of reduced glutathione (GSH), DT-diaphorase and glutathione reductase (GRd) to the toxicity of Cr (VI). Cr (VI) caused concentration dependent inhibition of protein, DNA and RNA synthesis in hepatocytes. GRd and to a lesser extent DT-diaphorase activities were involved in the generation of toxic intermediates. GRd activity was markedly inhibited during the reduction of Cr (VI), and GSH levels decreased. The concentrations of Cr (VI) found to inhibit macromolecular syntheses in this study are clinically relevant: it is therefore important to develop implants with minimum wear potential."
1290254,Peterson et al. 2008,Isolation of a novel chromium(III) binding protein from bovine liver tissue after chromium(VI) exposure,"In the ongoing investigation into the biological importance and toxicity issues surrounding the bioinorganic chemistry of chromium, the accepted literature procedure for the isolation of the biological form of chromium, low molecular weight chromium binding protein (LMWCr) or chromodulin, was investigated for its specificity. When chromium(VI) is added to bovine liver homogenate, results presented here indicate at least four chromium(III) binding peptides and proteins are produced and that the process is non-specific for the isolation of LMWCr. A novel trivalent chromium containing protein (1) has been isolated to purity and initial characterization is reported here. Chromium(III) identification was determined by optical spectroscopy and diphenylcarbazide testing. This chromium binding protein has a molecular weight of 15.6kDa, which was determined from both gel-electrophoresis and mass spectrometry. The protein is comprised primarily of Asx, Glx, His, Gly/Thr, Ala, and Lys in a 1.00:2.51:0.37:2.09:0.39:1.17 ratio and is anionic at pH 7.4. In addition, the protein binds approximately 2.5 chromium(III) ions per molecule.","Isolation of a novel chromium(III) binding protein from bovine liver tissue after chromium(VI) exposure Abs: In the ongoing investigation into the biological importance and toxicity issues surrounding the bioinorganic chemistry of chromium, the accepted literature procedure for the isolation of the biological form of chromium, low molecular weight chromium binding protein (LMWCr) or chromodulin, was investigated for its specificity. When chromium(VI) is added to bovine liver homogenate, results presented here indicate at least four chromium(III) binding peptides and proteins are produced and that the process is non-specific for the isolation of LMWCr. A novel trivalent chromium containing protein (1) has been isolated to purity and initial characterization is reported here. Chromium(III) identification was determined by optical spectroscopy and diphenylcarbazide testing. This chromium binding protein has a molecular weight of 15.6kDa, which was determined from both gel-electrophoresis and mass spectrometry. The protein is comprised primarily of Asx, Glx, His, Gly/Thr, Ala, and Lys in a 1.00:2.51:0.37:2.09:0.39:1.17 ratio and is anionic at pH 7.4. In addition, the protein binds approximately 2.5 chromium(III) ions per molecule."
1290253,Suwalsky et al. 2008,Cr(III) exerts stronger structural effects than Cr(VI) on the human erythrocyte membrane and molecular models,"Chromium exists in many oxidation states, of which only the hexavalent Cr(VI) and the trivalent Cr(III) ions are stable under environmental conditions. It is generally reported that Cr(VI) is highly toxic while Cr(III) is relatively innocuous, although others have reported just the opposite. On the other hand, despite the many studies on chromium toxicity, and particularly after the knowledge that Cr(VI) anions readily enter the erythrocytes where they are reduced to Cr(III), there are practically no reports on the structural effects induced by chromium compounds on the erythrocyte membrane. With the aim to better understand the molecular mechanisms of the interaction of Cr(III) and Cr(VI) with cell membranes, CrCl(3), and K(2)CrO(4) were incubated with intact erythrocytes, isolated unsealed human erythrocyte membranes (IUM), and molecular models of the erythrocyte membrane. These consisted in bilayers built-up of dimyristoylphosphatidylcholine (DMPC) and dimyristoylphosphatidylcholine (DMPE), phospholipid classes present in the outer and inner monolayers of the erythrocyte membrane, respectively. The capacity of Cr(III) and Cr(VI) to perturb the bilayer structures of DMPC and DMPE was evaluated by X-ray diffraction, DMPC large unilamellar vesicles (LUV) and IUM were studied by fluorescence spectroscopy, and intact human erythrocytes were observed with scanning electron microscopy (SEM). In all these systems, it was found that Cr(III) induced considerably higher structural perturbations than Cr(VI).","Cr(III) exerts stronger structural effects than Cr(VI) on the human erythrocyte membrane and molecular models Abs: Chromium exists in many oxidation states, of which only the hexavalent Cr(VI) and the trivalent Cr(III) ions are stable under environmental conditions. It is generally reported that Cr(VI) is highly toxic while Cr(III) is relatively innocuous, although others have reported just the opposite. On the other hand, despite the many studies on chromium toxicity, and particularly after the knowledge that Cr(VI) anions readily enter the erythrocytes where they are reduced to Cr(III), there are practically no reports on the structural effects induced by chromium compounds on the erythrocyte membrane. With the aim to better understand the molecular mechanisms of the interaction of Cr(III) and Cr(VI) with cell membranes, CrCl(3), and K(2)CrO(4) were incubated with intact erythrocytes, isolated unsealed human erythrocyte membranes (IUM), and molecular models of the erythrocyte membrane. These consisted in bilayers built-up of dimyristoylphosphatidylcholine (DMPC) and dimyristoylphosphatidylcholine (DMPE), phospholipid classes present in the outer and inner monolayers of the erythrocyte membrane, respectively. The capacity of Cr(III) and Cr(VI) to perturb the bilayer structures of DMPC and DMPE was evaluated by X-ray diffraction, DMPC large unilamellar vesicles (LUV) and IUM were studied by fluorescence spectroscopy, and intact human erythrocytes were observed with scanning electron microscopy (SEM). In all these systems, it was found that Cr(III) induced considerably higher structural perturbations than Cr(VI)."
1290251,He et al. 2007,Protection against chromium (VI)-induced oxidative stress and apoptosis by Nrf2. Recruiting Nrf2 into the nucleus and disrupting the nuclear Nrf2/Keap1 association,"Chromium (Cr) (VI) is a major environmental toxic metal and a human carcinogen. The molecular events mediating cellular responses to Cr(VI) are not clear at present. We show that Cr(VI) potently induced apoptosis and production of reactive oxygen species (ROS) in mouse hepa1c1c7 cells in a concentration-dependent manner. Mouse embryonic fibroblast cells lacking Nrf2 exhibited elevated ROS production and apoptosis, which were markedly further increased by Cr(VI), suggesting a protective role of Nrf2 against Cr(VI) toxicity. Protection by Nrf2 correlated with induction of cytoprotective genes Ho-1 and Nqo1. Induction of the genes by Cr(VI) involved inhibition of ubiquitination of Nrf2 and accumulation of Nrf2 into the nucleus. In the nucleus, treatment with Cr(VI), but not phenolic antioxidant tert-butylhydroquinone, librates Nrf2 from the Nrf2/Keap1 association and recruits Nrf2 to the antioxidant response elements (ARE) located in the enhancers of Ho-1 and Nqo1. Activation of Nrf2 by Cr(VI) was accompanied by the nuclear translocation and deubiquitination of Keap1 implicating recycling of Keap1 in Nrf2 signaling. Thus, protection against Cr(VI) toxicity involves a transcriptional signaling loop that includes activation of Nrf2 by the toxic metal, transcription of ARE-driven genes, and reduction of ROS production.","Protection against chromium (VI)-induced oxidative stress and apoptosis by Nrf2. Recruiting Nrf2 into the nucleus and disrupting the nuclear Nrf2/Keap1 association Abs: Chromium (Cr) (VI) is a major environmental toxic metal and a human carcinogen. The molecular events mediating cellular responses to Cr(VI) are not clear at present. We show that Cr(VI) potently induced apoptosis and production of reactive oxygen species (ROS) in mouse hepa1c1c7 cells in a concentration-dependent manner. Mouse embryonic fibroblast cells lacking Nrf2 exhibited elevated ROS production and apoptosis, which were markedly further increased by Cr(VI), suggesting a protective role of Nrf2 against Cr(VI) toxicity. Protection by Nrf2 correlated with induction of cytoprotective genes Ho-1 and Nqo1. Induction of the genes by Cr(VI) involved inhibition of ubiquitination of Nrf2 and accumulation of Nrf2 into the nucleus. In the nucleus, treatment with Cr(VI), but not phenolic antioxidant tert-butylhydroquinone, librates Nrf2 from the Nrf2/Keap1 association and recruits Nrf2 to the antioxidant response elements (ARE) located in the enhancers of Ho-1 and Nqo1. Activation of Nrf2 by Cr(VI) was accompanied by the nuclear translocation and deubiquitination of Keap1 implicating recycling of Keap1 in Nrf2 signaling. Thus, protection against Cr(VI) toxicity involves a transcriptional signaling loop that includes activation of Nrf2 by the toxic metal, transcription of ARE-driven genes, and reduction of ROS production."
1290250,Guo et al. 2007,Influence of Cr(III) and Cr(VI) on the interaction between sparfloxacin and calf thymus DNA,"Cr(III) and Cr(VI) have different binding capacity with sparfloxacin, and have different combination modes with calf thymus DNA. Selecting these two different metal ions, the influence of them on the binding constants between sparfloxacin (SPFX) and calf thymus DNA, as well as the related mechanism has been studied by using absorption and fluorescence spectroscopy. The result shows that Cr(III) has weaker binding capacity to SPFX in the SPFX-Cr(III) binary system, but influences the binding between SPFX and DNA obviously in SPFX-DNA-Cr(III) ternary system. However, although Cr(VI) has a stronger binding capacity to SPFX, it has no effect on the binding between SPFX and DNA. Referring to the different modes of Cr(III) and Cr(VI) binding to DNA, the mechanism of the influence of metal ions on the binding between SPFX and DNA has been proposed. SPFX can directly bind to DNA by chelating DNA base sites. If a metal ion at certain concentration binds mainly to DNA bases, it can decrease the binding constants between SPFX and DNA through competing with SPFX. While if a metal ion at certain concentration mainly binds to phosphate groups of DNA, it can increase the binding constants by building a bridge between SPFX and DNA. If a metal ion at certain concentrations binds neither to bases nor phosphate groups in DNA, it will have no effect on the binding constant between SPFX and DNA. Our result supports Palumbo's conclusion that the binding between SPFX and the phosphata groups is the precondition for the combination between SPFX and DNA, which is stabilized through stacking interactions between the condensed rings of SPFX and DNA bases.","Influence of Cr(III) and Cr(VI) on the interaction between sparfloxacin and calf thymus DNA Abs: Cr(III) and Cr(VI) have different binding capacity with sparfloxacin, and have different combination modes with calf thymus DNA. Selecting these two different metal ions, the influence of them on the binding constants between sparfloxacin (SPFX) and calf thymus DNA, as well as the related mechanism has been studied by using absorption and fluorescence spectroscopy. The result shows that Cr(III) has weaker binding capacity to SPFX in the SPFX-Cr(III) binary system, but influences the binding between SPFX and DNA obviously in SPFX-DNA-Cr(III) ternary system. However, although Cr(VI) has a stronger binding capacity to SPFX, it has no effect on the binding between SPFX and DNA. Referring to the different modes of Cr(III) and Cr(VI) binding to DNA, the mechanism of the influence of metal ions on the binding between SPFX and DNA has been proposed. SPFX can directly bind to DNA by chelating DNA base sites. If a metal ion at certain concentration binds mainly to DNA bases, it can decrease the binding constants between SPFX and DNA through competing with SPFX. While if a metal ion at certain concentration mainly binds to phosphate groups of DNA, it can increase the binding constants by building a bridge between SPFX and DNA. If a metal ion at certain concentrations binds neither to bases nor phosphate groups in DNA, it will have no effect on the binding constant between SPFX and DNA. Our result supports Palumbo's conclusion that the binding between SPFX and the phosphata groups is the precondition for the combination between SPFX and DNA, which is stabilized through stacking interactions between the condensed rings of SPFX and DNA bases."
1290249,Reynolds et al. 2007,Ascorbate acts as a highly potent inducer of chromate mutagenesis and clastogenesis: linkage to DNA breaks in G2 phase by mismatch repair,"Here we examined the role of cellular vitamin C in genotoxicity of carcinogenic chromium(VI) that requires reduction to induce DNA damage. In the presence of ascorbate (Asc), low 0.2-2 microM doses of Cr(VI) caused 10-15 times more chromosomal breakage in primary human bronchial epithelial cells or lung fibroblasts. DNA double-strand breaks (DSB) were preferentially generated in G2 phase as detected by colocalization of H2AX and 53BP1 foci in cyclin B1-expressing cells. Asc dramatically increased the formation of centromere-negative micronuclei, demonstrating that induced DSB were inefficiently repaired. DSB in G2 cells were caused by aberrant mismatch repair of Cr damage in replicated DNA, as DNA polymerase inhibitor aphidicolin and silencing of MSH2 or MLH1 by shRNA suppressed induction of H2AX and micronuclei. Cr(VI) was also up to 10 times more mutagenic in cells containing Asc. Increasing Asc concentrations generated progressively more mutations and DSB, revealing the genotoxic potential of otherwise nontoxic Cr(VI) doses. Asc amplified genotoxicity of Cr(VI) by altering the spectrum of DNA damage, as total Cr-DNA binding was unchanged and post-Cr loading of Asc exhibited no effects. Collectively, these studies demonstrated that Asc-dependent metabolism is the main source of genotoxic and mutagenic damage in Cr(VI)-exposed cells.","Ascorbate acts as a highly potent inducer of chromate mutagenesis and clastogenesis: linkage to DNA breaks in G2 phase by mismatch repair Abs: Here we examined the role of cellular vitamin C in genotoxicity of carcinogenic chromium(VI) that requires reduction to induce DNA damage. In the presence of ascorbate (Asc), low 0.2-2 microM doses of Cr(VI) caused 10-15 times more chromosomal breakage in primary human bronchial epithelial cells or lung fibroblasts. DNA double-strand breaks (DSB) were preferentially generated in G2 phase as detected by colocalization of H2AX and 53BP1 foci in cyclin B1-expressing cells. Asc dramatically increased the formation of centromere-negative micronuclei, demonstrating that induced DSB were inefficiently repaired. DSB in G2 cells were caused by aberrant mismatch repair of Cr damage in replicated DNA, as DNA polymerase inhibitor aphidicolin and silencing of MSH2 or MLH1 by shRNA suppressed induction of H2AX and micronuclei. Cr(VI) was also up to 10 times more mutagenic in cells containing Asc. Increasing Asc concentrations generated progressively more mutations and DSB, revealing the genotoxic potential of otherwise nontoxic Cr(VI) doses. Asc amplified genotoxicity of Cr(VI) by altering the spectrum of DNA damage, as total Cr-DNA binding was unchanged and post-Cr loading of Asc exhibited no effects. Collectively, these studies demonstrated that Asc-dependent metabolism is the main source of genotoxic and mutagenic damage in Cr(VI)-exposed cells."
1290248,Mcconnell 2006,The case of chromium (VI),,The case of chromium (VI) Abs: 
1290247,O'Hara et al. 2007,Cr(VI)-stimulated STAT3 tyrosine phosphorylation and nuclear translocation in human airway epithelial cells requires Lck,"Chronic inhalation of low amounts of Cr(VI) promotes pulmonary diseases and cancers through poorly defined mechanisms. SFKs (Src family kinases) in pulmonary airway cells may mediate Cr(VI) signalling for lung injury, although the downstream effectors of Cr(VI)-stimulated SFKs and how they relate to pathogenic gene induction are unknown. Therefore SFK-dependent activation of transcription factors by non-cytotoxic exposure of human bronchial epithelial cells to Cr(VI) was determined. Protein-DNA binding arrays demonstrated that exposing BEAS 2B cells to 5 microM Cr(VI) for 4 and 24 h resulted in increased protein binding to 25 and 43 cis-elements respectively, while binding to 12 and 16 cis-elements decreased. Of note, Cr(VI) increased protein binding to several STAT (signal transducer and activator of transcription) cis-elements. Cr(VI) stimulated acute tyrosine phosphorylation and nuclear translocation of STAT1 over a 4 h period and a prolonged activation of STAT3 that reached a peak between 48 and 72 h. This prolonged activation was observed for both STAT3alpha and STAT3beta. Immunofluorescent confocal microscopy confirmed that Cr(VI) increased nuclear localization of phosphorylated STAT3 for more than 72 h in both primary and BEAS 2B human airway cells. Cr(VI) induced transactivation of both a STAT3-driven luciferase reporter construct and the endogenous inflammatory gene IL-6 (interleukin-6). Inhibition with siRNA (small interfering RNA) targeting the SFK Lck, but not dominant-negative JAK (Janus kinase), prevented Cr(VI)-stimulated phosphorylation of both STAT3 isoforms and induction of IL-6. The results suggest that Cr(VI) activates epithelial cell Lck to signal for prolonged STAT3 activation and transactivation of IL-6, an important immunomodulator of lung disease progression.","Cr(VI)-stimulated STAT3 tyrosine phosphorylation and nuclear translocation in human airway epithelial cells requires Lck Abs: Chronic inhalation of low amounts of Cr(VI) promotes pulmonary diseases and cancers through poorly defined mechanisms. SFKs (Src family kinases) in pulmonary airway cells may mediate Cr(VI) signalling for lung injury, although the downstream effectors of Cr(VI)-stimulated SFKs and how they relate to pathogenic gene induction are unknown. Therefore SFK-dependent activation of transcription factors by non-cytotoxic exposure of human bronchial epithelial cells to Cr(VI) was determined. Protein-DNA binding arrays demonstrated that exposing BEAS 2B cells to 5 microM Cr(VI) for 4 and 24 h resulted in increased protein binding to 25 and 43 cis-elements respectively, while binding to 12 and 16 cis-elements decreased. Of note, Cr(VI) increased protein binding to several STAT (signal transducer and activator of transcription) cis-elements. Cr(VI) stimulated acute tyrosine phosphorylation and nuclear translocation of STAT1 over a 4 h period and a prolonged activation of STAT3 that reached a peak between 48 and 72 h. This prolonged activation was observed for both STAT3alpha and STAT3beta. Immunofluorescent confocal microscopy confirmed that Cr(VI) increased nuclear localization of phosphorylated STAT3 for more than 72 h in both primary and BEAS 2B human airway cells. Cr(VI) induced transactivation of both a STAT3-driven luciferase reporter construct and the endogenous inflammatory gene IL-6 (interleukin-6). Inhibition with siRNA (small interfering RNA) targeting the SFK Lck, but not dominant-negative JAK (Janus kinase), prevented Cr(VI)-stimulated phosphorylation of both STAT3 isoforms and induction of IL-6. The results suggest that Cr(VI) activates epithelial cell Lck to signal for prolonged STAT3 activation and transactivation of IL-6, an important immunomodulator of lung disease progression."
1290246,Yadav and  Trivedi 2006,Evaluation of genotoxic potential of chromium (VI) in Channa punctata fish in terms of chromosomal aberrations,"Chromium, a widely recognized carcinogenic, mutagenic and redox active metal, is released into aquatic environments by electroplating, tannery and textile industries. Elevated concentrations in sediments and interstitial waters are well documented. Fishes dwelling in chromium waste infested waters are presumed to be affected by its deposits. To evaluate the genotoxic potential of chromium [Cr(VI)] on aquatic bio-system, bottom feeding fishes, Channa punctata, as model fish, were exposed to [Cr(VI)]. The chromosomal aberration test (CAT) was used as biomarker of [Cr(VI)] induced toxicity. The fish were divided into three groups:Group I non-treated controls; group II positive controls, treated with an intra-muscular injection of mitomycin-C at 1 mg/kg body wt; group III exposed to a sublethal concentration (7.689 mg/l) of [Cr(VI)], dissolved in the water. For CAT estimation, short term static bioassays were conducted and samples were collected from the kidneys of fish after 24, 48, 72, 96 and 168 hrs of exposure. The remarkable chromosomal aberrations recorded in the present investigation included chromatid breaks, chromosome breaks, chromatid deletions, fragments, acentric fragments, and ring and di-centric chromosomes, along with chromatid and chromosome gaps. A significant increase in chromosomal aberrations was observed after 72 hrs of [Cr(VI)] exposure. The present study, thus reveals that even for acute exposure, [Cr(VI)] is a genotoxic agent for C. punctata.","Evaluation of genotoxic potential of chromium (VI) in Channa punctata fish in terms of chromosomal aberrations Abs: Chromium, a widely recognized carcinogenic, mutagenic and redox active metal, is released into aquatic environments by electroplating, tannery and textile industries. Elevated concentrations in sediments and interstitial waters are well documented. Fishes dwelling in chromium waste infested waters are presumed to be affected by its deposits. To evaluate the genotoxic potential of chromium [Cr(VI)] on aquatic bio-system, bottom feeding fishes, Channa punctata, as model fish, were exposed to [Cr(VI)]. The chromosomal aberration test (CAT) was used as biomarker of [Cr(VI)] induced toxicity. The fish were divided into three groups:Group I non-treated controls; group II positive controls, treated with an intra-muscular injection of mitomycin-C at 1 mg/kg body wt; group III exposed to a sublethal concentration (7.689 mg/l) of [Cr(VI)], dissolved in the water. For CAT estimation, short term static bioassays were conducted and samples were collected from the kidneys of fish after 24, 48, 72, 96 and 168 hrs of exposure. The remarkable chromosomal aberrations recorded in the present investigation included chromatid breaks, chromosome breaks, chromatid deletions, fragments, acentric fragments, and ring and di-centric chromosomes, along with chromatid and chromosome gaps. A significant increase in chromosomal aberrations was observed after 72 hrs of [Cr(VI)] exposure. The present study, thus reveals that even for acute exposure, [Cr(VI)] is a genotoxic agent for C. punctata."
1290245,Burastero et al. 2006,Chromium (VI)-induced immunotoxicity and intracellular accumulation in human primary dendritic cells,"Chromium compounds, besides being occupational carcinogens, can also induce allergic contact dermatitis (ACD) and other immunomodulatory effects. In this study we investigate cell viability, uptake and intracellular distribution of chromium in human primary dendritic cells (DCs), either immature (iDCs) or driven to differentiate by a specific maturation stimulus (LPS) (mature DCs, mDCs), when exposed for 48 h to concentrations of soluble radiolabelled Na251CrO4 ranging from 5 to 0.5 microM. The modulation of the expression of membrane markers (CD80, CD86, MHC class II) correlated with the immunological functions of DCs was also measured. After 48 h of exposure the mean IC50 values in 4 donors were 36 and 31 microM in iDCs and mDC respectively, as detected by propidium iodide incorporation. Cellular uptake of chromium was nearly linear with increasing doses. At 48 h post-exposure chromium was accumulated preferentially in the nuclear and cytosolic fractions (44.1 to 66% and 13.1 to 31% of total cellular chromium, respectively). Although a high inter-individual variability was observed, an increase in the expression of CD86 and, to a lower extent, CD80 and MHC class II membrane markers was found in mDCs of single donors. These results highlight the relevance of searching for the biodistribution of trace metals in primary cells of the immune system. Moreover, they suggest that DCs differentiation markers can help in measuring the immunotoxicity of metal compounds with sensitisation potential.","Chromium (VI)-induced immunotoxicity and intracellular accumulation in human primary dendritic cells Abs: Chromium compounds, besides being occupational carcinogens, can also induce allergic contact dermatitis (ACD) and other immunomodulatory effects. In this study we investigate cell viability, uptake and intracellular distribution of chromium in human primary dendritic cells (DCs), either immature (iDCs) or driven to differentiate by a specific maturation stimulus (LPS) (mature DCs, mDCs), when exposed for 48 h to concentrations of soluble radiolabelled Na251CrO4 ranging from 5 to 0.5 microM. The modulation of the expression of membrane markers (CD80, CD86, MHC class II) correlated with the immunological functions of DCs was also measured. After 48 h of exposure the mean IC50 values in 4 donors were 36 and 31 microM in iDCs and mDC respectively, as detected by propidium iodide incorporation. Cellular uptake of chromium was nearly linear with increasing doses. At 48 h post-exposure chromium was accumulated preferentially in the nuclear and cytosolic fractions (44.1 to 66% and 13.1 to 31% of total cellular chromium, respectively). Although a high inter-individual variability was observed, an increase in the expression of CD86 and, to a lower extent, CD80 and MHC class II membrane markers was found in mDCs of single donors. These results highlight the relevance of searching for the biodistribution of trace metals in primary cells of the immune system. Moreover, they suggest that DCs differentiation markers can help in measuring the immunotoxicity of metal compounds with sensitisation potential."
1290243,Bryant et al. 2006,Homologous recombination is involved in repair of chromium-induced DNA damage in mammalian cells,"Chromium is a potent human carcinogen, probably because of its well-documented genotoxic effects. Chromate (Cr[VI]) causes a wide range of DNA lesions, including DNA crosslinks and strand breaks, presumably due to the direct and indirect effects of DNA oxidation. Homologous recombination repair (HRR) is important for error-free repair of lesions occurring at replication forks. Here, we show that HR deficient cell lines irs1SF and V-C8, deficient in XRCC3 and BRCA2, respectively, are hypersensitive to Cr[VI], implicating this repair pathway in repair of Cr[VI] damage. Furthermore, we find that Cr[VI] causes DNA double-strand breaks and triggers both Rad51 foci formation and induction of HRR. Collectively, these data suggest that HRR is important in repair of Cr[VI]-induced DNA damage. In addition, we find that ERCC1, XRCC1 and DNA-PKcs defective cells are hypersensitive to Cr[VI], indicating that several repair pathways cooperate in repairing Cr[VI]-induced DNA damage.","Homologous recombination is involved in repair of chromium-induced DNA damage in mammalian cells Abs: Chromium is a potent human carcinogen, probably because of its well-documented genotoxic effects. Chromate (Cr[VI]) causes a wide range of DNA lesions, including DNA crosslinks and strand breaks, presumably due to the direct and indirect effects of DNA oxidation. Homologous recombination repair (HRR) is important for error-free repair of lesions occurring at replication forks. Here, we show that HR deficient cell lines irs1SF and V-C8, deficient in XRCC3 and BRCA2, respectively, are hypersensitive to Cr[VI], implicating this repair pathway in repair of Cr[VI] damage. Furthermore, we find that Cr[VI] causes DNA double-strand breaks and triggers both Rad51 foci formation and induction of HRR. Collectively, these data suggest that HRR is important in repair of Cr[VI]-induced DNA damage. In addition, we find that ERCC1, XRCC1 and DNA-PKcs defective cells are hypersensitive to Cr[VI], indicating that several repair pathways cooperate in repairing Cr[VI]-induced DNA damage."
1290242,Vandana et al. 2006,"Comparative cytoprotective activity of vitamin C, E and beta-carotene against chromium induced oxidative stress in murine macrophages","The present study reports the cytoprotective efficacy of vitamin C, E and beta-carotene against chromium (VI) induced oxidative stress in murine macrophages. Addition of chromium (VI) resulted in enhanced cytotoxicity as revealed by fall in neutral red uptake and increase in LDH release compared to control cells. Further there was an appreciable increase in apoptosis, ROS production and fall in reduced glutathione (GSH), glutathione peroxidase (GPx) and superoxide dismutase (SOD) activities. Chromium also inhibited macrophage proliferation and phagocytic activity. Addition of vitamin C but not vitamin E and beta-carotene inhibited chromium induced cytotoxicity, ROS generation and apoptosis. Vitamin C significantly inhibited NO production, enhanced macrophage proliferation and phagocytic activity while vitamin E and beta-carotene had marginal effect.","Comparative cytoprotective activity of vitamin C, E and beta-carotene against chromium induced oxidative stress in murine macrophages Abs: The present study reports the cytoprotective efficacy of vitamin C, E and beta-carotene against chromium (VI) induced oxidative stress in murine macrophages. Addition of chromium (VI) resulted in enhanced cytotoxicity as revealed by fall in neutral red uptake and increase in LDH release compared to control cells. Further there was an appreciable increase in apoptosis, ROS production and fall in reduced glutathione (GSH), glutathione peroxidase (GPx) and superoxide dismutase (SOD) activities. Chromium also inhibited macrophage proliferation and phagocytic activity. Addition of vitamin C but not vitamin E and beta-carotene inhibited chromium induced cytotoxicity, ROS generation and apoptosis. Vitamin C significantly inhibited NO production, enhanced macrophage proliferation and phagocytic activity while vitamin E and beta-carotene had marginal effect."
1290241,Li et al. 2005,Oxidative stress related enzymes in response to chromium (VI) toxicity in Oxya chinensis (Orthoptera: Acridoidae),"The toxic effects of Cr(VI) on antioxidant enzymes of Oxya chinensis (Orthoptera: Acridoidae) were determined. Changes in the activities of the antioxidant enzymes superoxide dismutase (SOD), catalase (CAT), and guaiacol peroxidase (GPx) were measured in O. chinensis insects injected with Cr(VI). Fifth-nymphs of O. chinensis insects were injected with Cr(VI) with different concentrations (0, 75, 150, 225, 300, 375, 450 mg/kg of body weight). The results showed that Cr(VI) led to the change of SOD, CAT, and GPx activities at different concentrations, which revealed that: (1) The oxidative stress of SOD increased with the increase of Cr(VI) concentration. (2) With the increase of Cr(VI) concentrations, CAT activities for females increased at lower concentrations, but decreased at higher concentration range, which indicated that antioxidant system of O. chinensis was not influenced by the presence of Cr(VI). A very similar response to Cr(VI) effect for males indicated that Cr(VI) concentrations were not high enough to damage O. chinensis in terms of CAT. (3) The GPx activity for females increased in all treatments, which revealed that the damage power of Cr(VI) was increased with the increase of Cr(VI) concentrations in terms of GPx, but the effect was not so remarkable. There was not a consistent trend of GPx activities for males in all treatments of Cr(VI). Cr (VI)-induced changes in antioxidant enzymes were different for SOD, CAT and GPx, of which the tendency was that activities generally changed with increase of concentrations of Cr(VI) suggesting SOD, CAT, and GPx could serve as indices of oxidative stress to some extent.","Oxidative stress related enzymes in response to chromium (VI) toxicity in Oxya chinensis (Orthoptera: Acridoidae) Abs: The toxic effects of Cr(VI) on antioxidant enzymes of Oxya chinensis (Orthoptera: Acridoidae) were determined. Changes in the activities of the antioxidant enzymes superoxide dismutase (SOD), catalase (CAT), and guaiacol peroxidase (GPx) were measured in O. chinensis insects injected with Cr(VI). Fifth-nymphs of O. chinensis insects were injected with Cr(VI) with different concentrations (0, 75, 150, 225, 300, 375, 450 mg/kg of body weight). The results showed that Cr(VI) led to the change of SOD, CAT, and GPx activities at different concentrations, which revealed that: (1) The oxidative stress of SOD increased with the increase of Cr(VI) concentration. (2) With the increase of Cr(VI) concentrations, CAT activities for females increased at lower concentrations, but decreased at higher concentration range, which indicated that antioxidant system of O. chinensis was not influenced by the presence of Cr(VI). A very similar response to Cr(VI) effect for males indicated that Cr(VI) concentrations were not high enough to damage O. chinensis in terms of CAT. (3) The GPx activity for females increased in all treatments, which revealed that the damage power of Cr(VI) was increased with the increase of Cr(VI) concentrations in terms of GPx, but the effect was not so remarkable. There was not a consistent trend of GPx activities for males in all treatments of Cr(VI). Cr (VI)-induced changes in antioxidant enzymes were different for SOD, CAT and GPx, of which the tendency was that activities generally changed with increase of concentrations of Cr(VI) suggesting SOD, CAT, and GPx could serve as indices of oxidative stress to some extent."
1290239,Cakir and  Biçer 2005,The interaction of cysteine with chromium(VI) ions under UV irradiation,"In 0.1 M phosphate buffer (pH 7.2), the interaction of chromium(VI) with cysteine in the presence and absence of UV irradiation was studied by cyclic voltammetry and electronic spectroscopy techniques. The reduction of Cr(VI) by cysteine takes place through the formation of Cr(VI)-thioester intermediate. On the cyclic voltammograms of cysteine and Cr(VI) mixture, the peaks at -0.315 and -0.800 V were observed, and these peaks are corresponding to the reduction of Cr(VI)-thioester and thiyl radical, respectively. In the cysteine solution exposed to UV irradiation, the formation of free cystine was observed at -0.792 V. In the cysteine and Cr(VI) mixture exposed to UV irradiation, the peak current of thiyl radical increases while the peak current of Cr(VI)-thioester reaches a maximum at 15 min and then decreases by increasing UV irradiation time. The formation of the thioester in the reaction between Cr(VI) and cysteine in aqueous media has been studied by monitoring the decrease of Cr(VI) at 370 nm. It was observed that the reaction is catalyzed by the UV irradiation of the Cr(VI) and cysteine mixture.","The interaction of cysteine with chromium(VI) ions under UV irradiation Abs: In 0.1 M phosphate buffer (pH 7.2), the interaction of chromium(VI) with cysteine in the presence and absence of UV irradiation was studied by cyclic voltammetry and electronic spectroscopy techniques. The reduction of Cr(VI) by cysteine takes place through the formation of Cr(VI)-thioester intermediate. On the cyclic voltammograms of cysteine and Cr(VI) mixture, the peaks at -0.315 and -0.800 V were observed, and these peaks are corresponding to the reduction of Cr(VI)-thioester and thiyl radical, respectively. In the cysteine solution exposed to UV irradiation, the formation of free cystine was observed at -0.792 V. In the cysteine and Cr(VI) mixture exposed to UV irradiation, the peak current of thiyl radical increases while the peak current of Cr(VI)-thioester reaches a maximum at 15 min and then decreases by increasing UV irradiation time. The formation of the thioester in the reaction between Cr(VI) and cysteine in aqueous media has been studied by monitoring the decrease of Cr(VI) at 370 nm. It was observed that the reaction is catalyzed by the UV irradiation of the Cr(VI) and cysteine mixture."
1290238,Peterson-Roth et al. 2005,Mismatch repair proteins are activators of toxic responses to chromium-DNA damage,"Chromium(VI) is a toxic and carcinogenic metal that causes the formation of DNA phosphate-based adducts. Cr-DNA adducts are genotoxic in human cells, although they do not block replication in vitro. Here, we report that induction of cytotoxicity in Cr(VI)-treated human colon cells and mouse embryonic fibroblasts requires the presence of all major mismatch repair (MMR) proteins. Cr-DNA adducts lost their ability to block replication of Cr-modified plasmids in human colon cells lacking MLH1 protein. The presence of functional mismatch repair caused induction of p53-independent apoptosis associated with activation of caspases 2 and 7. Processing of Cr-DNA damage by mismatch repair resulted in the extensive formation of gamma-H2AX foci in G(2) phase, indicating generation of double-stranded breaks as secondary toxic lesions. Induction of gamma-H2AX foci was observed at 6 to 12 h postexposure, which was followed by activation of apoptosis in the absence of significant G(2) arrest. Our results demonstrate that mismatch repair system triggers toxic responses to Cr-DNA backbone modifications through stress mechanisms that are significantly different from those for other forms of DNA damage. Selection for Cr(VI) resistant, MMR-deficient cells may explain the very high frequency of lung cancers with microsatellite instability among chromate workers.","Mismatch repair proteins are activators of toxic responses to chromium-DNA damage Abs: Chromium(VI) is a toxic and carcinogenic metal that causes the formation of DNA phosphate-based adducts. Cr-DNA adducts are genotoxic in human cells, although they do not block replication in vitro. Here, we report that induction of cytotoxicity in Cr(VI)-treated human colon cells and mouse embryonic fibroblasts requires the presence of all major mismatch repair (MMR) proteins. Cr-DNA adducts lost their ability to block replication of Cr-modified plasmids in human colon cells lacking MLH1 protein. The presence of functional mismatch repair caused induction of p53-independent apoptosis associated with activation of caspases 2 and 7. Processing of Cr-DNA damage by mismatch repair resulted in the extensive formation of gamma-H2AX foci in G(2) phase, indicating generation of double-stranded breaks as secondary toxic lesions. Induction of gamma-H2AX foci was observed at 6 to 12 h postexposure, which was followed by activation of apoptosis in the absence of significant G(2) arrest. Our results demonstrate that mismatch repair system triggers toxic responses to Cr-DNA backbone modifications through stress mechanisms that are significantly different from those for other forms of DNA damage. Selection for Cr(VI) resistant, MMR-deficient cells may explain the very high frequency of lung cancers with microsatellite instability among chromate workers."
1290236,Harris et al. 2005,"Time-dependent uptake, distribution and biotransformation of chromium(VI) in individual and bulk human lung cells: application of synchrotron radiation techniques","Chromium(VI) is a human carcinogen, primarily affecting the respiratory tract probably via active transport into cells, followed by the reduction to Cr(III) with the formation of DNA-damaging intermediates. Distribution of Cr and endogenous elements within A549 human lung adenocarcinoma epithelial cells, following treatment with Cr(VI) (100 microM, 20 min or 4 h) were studied by synchrotron-radiation-induced X-ray emission (SRIXE) of single freeze-dried cells. After the 20-min treatment, Cr was confined to a small area of the cytoplasm and strongly co-localized with S, Cl, K, and Ca. After the 4-h treatment, Cr was distributed throughout the cell, with higher concentrations in the nucleus and the cytoplasmic membrane. This time-dependence corresponded to approximately 100% or 0% clonogenic survival of the cells following the 20-min or 4-h treatments, respectively, and could potentially be explained by a new cellular protective mechanism. Such processes may also be important in reducing the potential hazards of Cr(III) dietary supplements, for which there is emerging evidence that they exert their anti-diabetic effects via biological oxidation to Cr(VI). The predominance of Cr(III) was confirmed by micro-XANES spectroscopy of intracellular Cr hotspots. X-ray absorption spectroscopy (XANES and EXAFS, using freeze-dried cells after the 0-4-h treatments) was used to gain insight into the chemical structures of Cr(III) complexes formed during the intracellular reduction of Cr(VI). The polynuclear nature of such complexes (probably with a combination of carboxylato and hydroxo bridging groups and O-donor atoms of small peptides or proteins) was established by XAFS data analyses.","Time-dependent uptake, distribution and biotransformation of chromium(VI) in individual and bulk human lung cells: application of synchrotron radiation techniques Abs: Chromium(VI) is a human carcinogen, primarily affecting the respiratory tract probably via active transport into cells, followed by the reduction to Cr(III) with the formation of DNA-damaging intermediates. Distribution of Cr and endogenous elements within A549 human lung adenocarcinoma epithelial cells, following treatment with Cr(VI) (100 microM, 20 min or 4 h) were studied by synchrotron-radiation-induced X-ray emission (SRIXE) of single freeze-dried cells. After the 20-min treatment, Cr was confined to a small area of the cytoplasm and strongly co-localized with S, Cl, K, and Ca. After the 4-h treatment, Cr was distributed throughout the cell, with higher concentrations in the nucleus and the cytoplasmic membrane. This time-dependence corresponded to approximately 100% or 0% clonogenic survival of the cells following the 20-min or 4-h treatments, respectively, and could potentially be explained by a new cellular protective mechanism. Such processes may also be important in reducing the potential hazards of Cr(III) dietary supplements, for which there is emerging evidence that they exert their anti-diabetic effects via biological oxidation to Cr(VI). The predominance of Cr(III) was confirmed by micro-XANES spectroscopy of intracellular Cr hotspots. X-ray absorption spectroscopy (XANES and EXAFS, using freeze-dried cells after the 0-4-h treatments) was used to gain insight into the chemical structures of Cr(III) complexes formed during the intracellular reduction of Cr(VI). The polynuclear nature of such complexes (probably with a combination of carboxylato and hydroxo bridging groups and O-donor atoms of small peptides or proteins) was established by XAFS data analyses."
1290235,Gunaratnam and  Grant 2001,"The interaction of the orthopaedic metals, chromium VI and nickel, with hepatocytes","High levels of metal ions, such as chromium and nickel, released from metallic total hip implants have been detected in the serum and urine of patients. Cr VI and Ni ions are carcinogenic and toxic and there is concern about their systemic toxicity. To investigate this we have studied the interaction of Cr VI and Ni with hepatocytes. Both metal ions caused loss of cell viability within 3 h exposure, Cr VI was more potent than Ni. Cr VI caused depletion of intracellular reduced glutathione (GSH) levels, and inhibition of glutathione reductase and glutathione-S-transferase (GST) activities. Expression of alpha-GST, the major isoenzyme of GST in rat liver, was also decreased by Cr VI. Ni, on the other hand did not deplete GSH, or inhibit any of the enzyme activities measured in the cells. GSH and GST form a major protection and detoxification system in the liver, and depletion of GSH and inhibition of GST activity by Cr VI in vivo may severely compromise the ability of an individual to protect himself against carcinogenic and cytotoxic chemicals in the environment.","The interaction of the orthopaedic metals, chromium VI and nickel, with hepatocytes Abs: High levels of metal ions, such as chromium and nickel, released from metallic total hip implants have been detected in the serum and urine of patients. Cr VI and Ni ions are carcinogenic and toxic and there is concern about their systemic toxicity. To investigate this we have studied the interaction of Cr VI and Ni with hepatocytes. Both metal ions caused loss of cell viability within 3 h exposure, Cr VI was more potent than Ni. Cr VI caused depletion of intracellular reduced glutathione (GSH) levels, and inhibition of glutathione reductase and glutathione-S-transferase (GST) activities. Expression of alpha-GST, the major isoenzyme of GST in rat liver, was also decreased by Cr VI. Ni, on the other hand did not deplete GSH, or inhibit any of the enzyme activities measured in the cells. GSH and GST form a major protection and detoxification system in the liver, and depletion of GSH and inhibition of GST activity by Cr VI in vivo may severely compromise the ability of an individual to protect himself against carcinogenic and cytotoxic chemicals in the environment."
1290234,Ning et al. 2002,The cytotoxicity of chromium in osteoblasts: Effects on macromolecular synthesis,"Exposure of an immortalized rat osteoblast cell line, FFC cells, to Cr VI resulted in inhibition of protein, DNA and RNA synthesis. Protein synthesis (3H-leucine incorporation) was most sensitive. There was no inhibition of the incorporation of 3H-proline into collagen at the concentrations which inhibited general protein synthesis (1 microM), but synthesis of extracellular collagen fibers was markedly decreased by concentrations of 0.5 microM Cr VI and above. This indicates that some aspect of the post-translational processing of the collagen fibers is sensitive to Cr VI inhibition. Collagen fiber formation was not inhibited by Cr III (which does not penetrate the cell membrane) or when Cr VI was reduced to Cr III extracellularly. This suggests that the Cr VI inhibits an intracellular stage of post-translational collagen processing. Both Cr VI and Cr III inhibit collagenase activity, the former being more potent but less efficacious. Our results suggest that leakage of chromium ions from orthopedic implants may cause a decrease in the proliferation and infiltration of osteoblasts around the implant, and a reduction in the synthesis and altered turnover of collagen in extracellular matrix. These effects will influence the osseointegration of implants, the osteolytic response, and ultimately the stable life-time of the implants.","The cytotoxicity of chromium in osteoblasts: Effects on macromolecular synthesis Abs: Exposure of an immortalized rat osteoblast cell line, FFC cells, to Cr VI resulted in inhibition of protein, DNA and RNA synthesis. Protein synthesis (3H-leucine incorporation) was most sensitive. There was no inhibition of the incorporation of 3H-proline into collagen at the concentrations which inhibited general protein synthesis (1 microM), but synthesis of extracellular collagen fibers was markedly decreased by concentrations of 0.5 microM Cr VI and above. This indicates that some aspect of the post-translational processing of the collagen fibers is sensitive to Cr VI inhibition. Collagen fiber formation was not inhibited by Cr III (which does not penetrate the cell membrane) or when Cr VI was reduced to Cr III extracellularly. This suggests that the Cr VI inhibits an intracellular stage of post-translational collagen processing. Both Cr VI and Cr III inhibit collagenase activity, the former being more potent but less efficacious. Our results suggest that leakage of chromium ions from orthopedic implants may cause a decrease in the proliferation and infiltration of osteoblasts around the implant, and a reduction in the synthesis and altered turnover of collagen in extracellular matrix. These effects will influence the osseointegration of implants, the osteolytic response, and ultimately the stable life-time of the implants."
1290233,Shayer et al. 2004,Biomonitoring of chromium(VI) deposited in pulmonary tissues: Pilot studies of a magnetic resonance imaging technique in a post-mortem rodent model,"The biomonitoring of individuals exposed to chromium(VI) by inhalation is often based on determinations of chromium in body fluids such as blood, plasma or urine, or on assessments of DNA damage in non-lung surrogate tissues such as peripheral blood lymphocytes. These techniques are of some use as biomarkers of internal exposure or biological effect, mainly in the case of soluble chromium(VI) compounds, but they provide at best only indirect information about chromium(VI) concentrations in the main target organ of interest - the lung. An urgent need exists for a non-invasive technique to permit the visualization and quantification of chromium(VI) in the lung of exposed humans. This study details the development of a lung imaging technique based on the detection of paramagnetic chromium using magnetic resonance imaging (MRI). The intracellular reductive conversion of chromium(VI) is a crucial bioactivation step in its carcinogenicity, and the MRI method described here relies on the conversion of non-paramagnetic (MRI 'silent') chromium(VI) to detectable paramagnetic species such as chromium(III). Initial studies with chromium(III) revealed that a range of 2.5-5 microg chromium(III) instilled in rat lung is considered to be the lower limit of detection of this method. It was possible to demonstrate the presence of 30 microg chromium(VI) in our post-mortem rat model. The ultimate objective of this work is to determine whether this technique has applicability to the biomonitoring of chromium(VI) inhalation exposures that result in internalized lung doses in human subjects.","Biomonitoring of chromium(VI) deposited in pulmonary tissues: Pilot studies of a magnetic resonance imaging technique in a post-mortem rodent model Abs: The biomonitoring of individuals exposed to chromium(VI) by inhalation is often based on determinations of chromium in body fluids such as blood, plasma or urine, or on assessments of DNA damage in non-lung surrogate tissues such as peripheral blood lymphocytes. These techniques are of some use as biomarkers of internal exposure or biological effect, mainly in the case of soluble chromium(VI) compounds, but they provide at best only indirect information about chromium(VI) concentrations in the main target organ of interest - the lung. An urgent need exists for a non-invasive technique to permit the visualization and quantification of chromium(VI) in the lung of exposed humans. This study details the development of a lung imaging technique based on the detection of paramagnetic chromium using magnetic resonance imaging (MRI). The intracellular reductive conversion of chromium(VI) is a crucial bioactivation step in its carcinogenicity, and the MRI method described here relies on the conversion of non-paramagnetic (MRI 'silent') chromium(VI) to detectable paramagnetic species such as chromium(III). Initial studies with chromium(III) revealed that a range of 2.5-5 microg chromium(III) instilled in rat lung is considered to be the lower limit of detection of this method. It was possible to demonstrate the presence of 30 microg chromium(VI) in our post-mortem rat model. The ultimate objective of this work is to determine whether this technique has applicability to the biomonitoring of chromium(VI) inhalation exposures that result in internalized lung doses in human subjects."
1290232,Upreti et al. 2004,Gut microflora &amp; toxic metals: chromium as a model,"The gastrointestinal tract (GIT) is exposed to various environmental pollutants including metals, that contaminate food and water which may have toxic effects on body. GIT has large amount of microbes that live in symbiosis and help the host in different ways. The resident gut microflora have a significant role to play in detoxification and elimination of the harmful metals from the body. Chromium is a naturally occurring heavy metal found commonly in environment in trivalent (Cr III) and hexavalent (Cr VI) forms. Cr (VI) compounds have been shown to be potent occupational carcinogens. The reduction of Cr (VI) to Cr (III) results in the formation of reactive intermediates that together with oxidative stress and oxidative tissue damage, and a cascade of cellular events including modulation of apoptosis regulatory gene p53 contribute to the cytotoxicity, genotoxicity and carcinogenicity of Cr(VI)-containing compounds. The data discussed here with reference to chromium show that gut microflora have a marked capacity to cope with the increased load of ingested metals and may contribute significantly in the protection against metal toxicity.","Gut microflora &amp; toxic metals: chromium as a model Abs: The gastrointestinal tract (GIT) is exposed to various environmental pollutants including metals, that contaminate food and water which may have toxic effects on body. GIT has large amount of microbes that live in symbiosis and help the host in different ways. The resident gut microflora have a significant role to play in detoxification and elimination of the harmful metals from the body. Chromium is a naturally occurring heavy metal found commonly in environment in trivalent (Cr III) and hexavalent (Cr VI) forms. Cr (VI) compounds have been shown to be potent occupational carcinogens. The reduction of Cr (VI) to Cr (III) results in the formation of reactive intermediates that together with oxidative stress and oxidative tissue damage, and a cascade of cellular events including modulation of apoptosis regulatory gene p53 contribute to the cytotoxicity, genotoxicity and carcinogenicity of Cr(VI)-containing compounds. The data discussed here with reference to chromium show that gut microflora have a marked capacity to cope with the increased load of ingested metals and may contribute significantly in the protection against metal toxicity."
1290231,Asatiani et al. 2004,Effects of Cr(VI) long-term and low-dose action on mammalian antioxidant enzymes (an in vitro study),"In order to investigate the low-dose long-term Cr(VI) action on antioxidant enzymes in cultured mammalian cells we estimated the activity of glutathione dependent antioxidant enzymes, catalase and superoxide dismutase (SOD) under various chromium concentrations in human epithelial-like L-41 cells. The long-term action of 20 microM causes the toxicity that results in losing of the cell viability by activating the apoptotic process, as identified by morphological analysis, the activation of caspase-3, and DNA fragmentation. The toxic chromium concentration totally destroys glutathione antioxidant system, and diminishes the activity of catalase and cytosolic Cu, ZnSOD. The non-toxic concentration (2 microM) causes the activation of the antioxidant defense systems, and they neutralize the oxidative impact.","Effects of Cr(VI) long-term and low-dose action on mammalian antioxidant enzymes (an in vitro study) Abs: In order to investigate the low-dose long-term Cr(VI) action on antioxidant enzymes in cultured mammalian cells we estimated the activity of glutathione dependent antioxidant enzymes, catalase and superoxide dismutase (SOD) under various chromium concentrations in human epithelial-like L-41 cells. The long-term action of 20 microM causes the toxicity that results in losing of the cell viability by activating the apoptotic process, as identified by morphological analysis, the activation of caspase-3, and DNA fragmentation. The toxic chromium concentration totally destroys glutathione antioxidant system, and diminishes the activity of catalase and cytosolic Cu, ZnSOD. The non-toxic concentration (2 microM) causes the activation of the antioxidant defense systems, and they neutralize the oxidative impact."
1290230,Xu et al. 2004,Mechanisms of chromium-induced suppression of RNA synthesis in cellular and cell-free systems: relationship to RNA polymerase arrest,"Chromium(VI) (Cr(VI)) can suppress both DNA replication and transcription as a result of chromium (Cr)-induced DNA damage. While progress has been made in the characterization of Cr-induced DNA polymerase arresting lesions, very little information is available on the inhibition of transcription by this metal. The aim of the present study was to identify the molecular mechanisms involved in the reduction of RNA synthesis by Cr. Following treatment with a moderately cytotoxic dose (approximately LC50) of Cr(VI) (150 microM for 2 h), total RNA synthesis was initially suppressed in CHO cells and recovered to control levels within 72 h post-treatment. In vitro nuclear run-on transcription assays of nuclei isolated from Cr(VI)-treated cells showed a similar amount of RNA synthesis suppression as observed in intact cells. Qualitative analysis of nascent transcripts revealed a general, concentration-dependent reduction in size suggesting that transcriptional elongation was inhibited following Cr-treatment. Transcriptional initiation in these nuclei was also reduced. To better determine whether transcriptional suppression was related to Cr-induced DNA damage we examined the transcriptional activity of T7 RNA polymerase on Cr(III)-treated plasmid DNA. Treatment of pGEM3Z-TS DNA with Cr(III) resulted in transcriptional arrest which occurred primarily at GC-rich and palindromic regions. However, in contrast to the cellular data, transcriptional initiation was unaffected in the in vitro transcription arrest assays. Taken together, these results suggest that the suppression of RNA synthesis by Cr is related to chromium-induced template DNA damage which prevents elongation leading to premature RNA polymerase arrest.","Mechanisms of chromium-induced suppression of RNA synthesis in cellular and cell-free systems: relationship to RNA polymerase arrest Abs: Chromium(VI) (Cr(VI)) can suppress both DNA replication and transcription as a result of chromium (Cr)-induced DNA damage. While progress has been made in the characterization of Cr-induced DNA polymerase arresting lesions, very little information is available on the inhibition of transcription by this metal. The aim of the present study was to identify the molecular mechanisms involved in the reduction of RNA synthesis by Cr. Following treatment with a moderately cytotoxic dose (approximately LC50) of Cr(VI) (150 microM for 2 h), total RNA synthesis was initially suppressed in CHO cells and recovered to control levels within 72 h post-treatment. In vitro nuclear run-on transcription assays of nuclei isolated from Cr(VI)-treated cells showed a similar amount of RNA synthesis suppression as observed in intact cells. Qualitative analysis of nascent transcripts revealed a general, concentration-dependent reduction in size suggesting that transcriptional elongation was inhibited following Cr-treatment. Transcriptional initiation in these nuclei was also reduced. To better determine whether transcriptional suppression was related to Cr-induced DNA damage we examined the transcriptional activity of T7 RNA polymerase on Cr(III)-treated plasmid DNA. Treatment of pGEM3Z-TS DNA with Cr(III) resulted in transcriptional arrest which occurred primarily at GC-rich and palindromic regions. However, in contrast to the cellular data, transcriptional initiation was unaffected in the in vitro transcription arrest assays. Taken together, these results suggest that the suppression of RNA synthesis by Cr is related to chromium-induced template DNA damage which prevents elongation leading to premature RNA polymerase arrest."
1290229,Levina and  Lay 2004,Solution structures of chromium(VI) complexes with glutathione and model thiols,"Chromium(VI) complexes of the most abundant biological reductant, glutathione (gamma-Glu-Cys-Gly, I), are among the likely initial reactive intermediates formed during the cellular metabolism of carcinogenic and genotoxic Cr(VI). Detailed structural characterization of such complexes in solutions has been performed by a combination of X-ray absorption fine structure (XAFS) and X-ray absorption near-edge structure (XANES) spectroscopies, electrospray mass spectrometry (ESMS), UV-vis spectroscopy, and kinetic studies. The Cr(VI) complexes of two model thiols, N-acetyl-2-mercaptoethylamine (II) and 4-bromobenzenethiol (III), were used for comparison. The Cr(VI)-thiolato complexes were generated quantitatively in weakly acidic aqueous solutions (for I and II) or in DMF solutions (for II) or isolated as a pure solid (for III). Contrary to some claims in the literature, no evidence was found for the formation of relatively stable Cr(IV) intermediates during the reactions of Cr(VI) with I in acidic aqueous solutions. The Cr(VI) complexes of I-III exist as tetrahedral [CrO(3)(SR)](-) (IVa) species in the solid state, in solutions of aprotic solvents such as DMF, or in the gas phase (under ESMS conditions). In aqueous or alcohol solutions, reversible addition of a solvent molecule occurs, with the formation of five-coordinate species, [CrO(3)(SR)L](-) (IVb, probably of a trigonal bipyramidal structure, L = H(2)O or MeOH), with a Cr-L bond length of 1.97(1) A (determined by XAFS data modeling). Complex IVb (L = H(2)O) is also formed (in an equilibrium mixture with [CrO(4)](2)(-)) at the first stage of reduction of Cr(VI) by I in neutral aqueous solutions (as shown by global kinetic analysis of time-dependent UV-vis spectra). This is the first observation of a reversible ligand addition reaction in Cr(VI) complexes. The formation of IVb (rather than IVa, as thought before) during the reactions of Cr(VI) with I in aqueous solutions is likely to be important for the reactivity of Cr(VI) in cellular media, including DNA and protein damage and inhibition of protein tyrosine phosphatases.","Solution structures of chromium(VI) complexes with glutathione and model thiols Abs: Chromium(VI) complexes of the most abundant biological reductant, glutathione (gamma-Glu-Cys-Gly, I), are among the likely initial reactive intermediates formed during the cellular metabolism of carcinogenic and genotoxic Cr(VI). Detailed structural characterization of such complexes in solutions has been performed by a combination of X-ray absorption fine structure (XAFS) and X-ray absorption near-edge structure (XANES) spectroscopies, electrospray mass spectrometry (ESMS), UV-vis spectroscopy, and kinetic studies. The Cr(VI) complexes of two model thiols, N-acetyl-2-mercaptoethylamine (II) and 4-bromobenzenethiol (III), were used for comparison. The Cr(VI)-thiolato complexes were generated quantitatively in weakly acidic aqueous solutions (for I and II) or in DMF solutions (for II) or isolated as a pure solid (for III). Contrary to some claims in the literature, no evidence was found for the formation of relatively stable Cr(IV) intermediates during the reactions of Cr(VI) with I in acidic aqueous solutions. The Cr(VI) complexes of I-III exist as tetrahedral [CrO(3)(SR)](-) (IVa) species in the solid state, in solutions of aprotic solvents such as DMF, or in the gas phase (under ESMS conditions). In aqueous or alcohol solutions, reversible addition of a solvent molecule occurs, with the formation of five-coordinate species, [CrO(3)(SR)L](-) (IVb, probably of a trigonal bipyramidal structure, L = H(2)O or MeOH), with a Cr-L bond length of 1.97(1) A (determined by XAFS data modeling). Complex IVb (L = H(2)O) is also formed (in an equilibrium mixture with [CrO(4)](2)(-)) at the first stage of reduction of Cr(VI) by I in neutral aqueous solutions (as shown by global kinetic analysis of time-dependent UV-vis spectra). This is the first observation of a reversible ligand addition reaction in Cr(VI) complexes. The formation of IVb (rather than IVa, as thought before) during the reactions of Cr(VI) with I in aqueous solutions is likely to be important for the reactivity of Cr(VI) in cellular media, including DNA and protein damage and inhibition of protein tyrosine phosphatases."
1290228,Vasant et al. 2003,Apoptosis of lymphocytes induced by chromium(VI/V) is through ROS-mediated activation of Src-family kinases and caspase-3,"Mechanistic insights into Cr(VI)-induced carcinogenicity and possible implication of Cr(V) species formed by the redox reactions of chromium-bearing species have attracted interest. We have previously demonstrated that when human peripheral blood lymphocytes are exposed to the Cr(V) complexes, viz., sodium bis(2-ethyl-2-hydroxybutyrato)oxochromate(V), Na[Cr(V)O(ehba)(2)] and sodium bis(2-hydroxy-2-methylbutyrato)oxochromate(V), Na[Cr(V)O(hmba)(2)], apoptosis and formation of reactive oxygen species (ROS) are observed. The molecular mechanisms involving cellular signaling pathways leading to apoptosis are addressed in the present study. Treatment of lymphocytes with Na[Cr(V)O(ehba)(2)] and K(2)Cr(2)O(7) leads to the activation of the Src-family protein tyrosine kinases namely, p56(lck), p59(fyn), and p56/53(lyn), which then activates caspase-3, both of which are under the partial influence of ROS. Inhibition of the Src-family tyrosine kinases activity by PP2 and of caspase-3 by Z-DEVD-FMK reverses apoptosis, thereby suggesting their importance. Antioxidants only partially reverse the apoptosis induced by Cr(VI/V), suggesting that pathways other than those induced by ROS cannot be ruled out. Although the complex, Na[Cr(V)O(ehba)(2)] is known to be relatively stable in aqueous solutions, previous studies have shown that the Cr(V) complex, Na[Cr(V)O(ehba)(2)] disproportionates to Cr(VI) and Cr(III) forms at pH 7.4 through complex mechanistic processes. Dynamics studies employing EPR data show that the Cr(V) state in Na[Cr(V)O(ehba)(2)] is relatively more stable in RPMI-1640 medium containing plasma. Formation of ROS during the reaction of redox partners with Na[Cr(V)O(ehba)(2)] is an early event and compares favorably in kinetic terms with the reported rate processes for disproportionation. This investigation presents evidence for the direct implication of Cr(V) in Cr(VI)-induced apoptosis of lymphocytes.","Apoptosis of lymphocytes induced by chromium(VI/V) is through ROS-mediated activation of Src-family kinases and caspase-3 Abs: Mechanistic insights into Cr(VI)-induced carcinogenicity and possible implication of Cr(V) species formed by the redox reactions of chromium-bearing species have attracted interest. We have previously demonstrated that when human peripheral blood lymphocytes are exposed to the Cr(V) complexes, viz., sodium bis(2-ethyl-2-hydroxybutyrato)oxochromate(V), Na[Cr(V)O(ehba)(2)] and sodium bis(2-hydroxy-2-methylbutyrato)oxochromate(V), Na[Cr(V)O(hmba)(2)], apoptosis and formation of reactive oxygen species (ROS) are observed. The molecular mechanisms involving cellular signaling pathways leading to apoptosis are addressed in the present study. Treatment of lymphocytes with Na[Cr(V)O(ehba)(2)] and K(2)Cr(2)O(7) leads to the activation of the Src-family protein tyrosine kinases namely, p56(lck), p59(fyn), and p56/53(lyn), which then activates caspase-3, both of which are under the partial influence of ROS. Inhibition of the Src-family tyrosine kinases activity by PP2 and of caspase-3 by Z-DEVD-FMK reverses apoptosis, thereby suggesting their importance. Antioxidants only partially reverse the apoptosis induced by Cr(VI/V), suggesting that pathways other than those induced by ROS cannot be ruled out. Although the complex, Na[Cr(V)O(ehba)(2)] is known to be relatively stable in aqueous solutions, previous studies have shown that the Cr(V) complex, Na[Cr(V)O(ehba)(2)] disproportionates to Cr(VI) and Cr(III) forms at pH 7.4 through complex mechanistic processes. Dynamics studies employing EPR data show that the Cr(V) state in Na[Cr(V)O(ehba)(2)] is relatively more stable in RPMI-1640 medium containing plasma. Formation of ROS during the reaction of redox partners with Na[Cr(V)O(ehba)(2)] is an early event and compares favorably in kinetic terms with the reported rate processes for disproportionation. This investigation presents evidence for the direct implication of Cr(V) in Cr(VI)-induced apoptosis of lymphocytes."
1290227,Pandima Devi et al. 2003,Immunomodulatory effects of Premna tomentosa extract against Cr (VI) induced toxicity in splenic lymphocytes--an in vitro study,"Premna tomentosa (L. Verbanacae) is a widely used medicinal plant. Our earlier studies show that the extract of P. tomentosa leaves prevents acetaminophen-induced hepatotoxicity owing to its antioxidant property. In the present study, we have investigated the immunomodulatory effects of P. tomentosa extract against Chromium (VI) induced immunosuppression in splenic lymphocytes. Chromium (Cr) addition at a concentration of 5 microg showed an increase in cytotoxicity, apoptosis and reactive oxygen species (ROS) and a decrease in lymphocyte proliferation and antioxidant levels, whereas pre-treatment of the cells with P. tomentosa extract (at 500 microg concentration) resulted in decreased cytotoxicity and ROS levels. Further, the drug treatment also maintained antioxidant levels and restored lymphocyte proliferation similar to that of control cells. The results indicated that the leaf extract of P. tomentosa has cytoprotective and immunomodulatory activities.","Immunomodulatory effects of Premna tomentosa extract against Cr (VI) induced toxicity in splenic lymphocytes--an in vitro study Abs: Premna tomentosa (L. Verbanacae) is a widely used medicinal plant. Our earlier studies show that the extract of P. tomentosa leaves prevents acetaminophen-induced hepatotoxicity owing to its antioxidant property. In the present study, we have investigated the immunomodulatory effects of P. tomentosa extract against Chromium (VI) induced immunosuppression in splenic lymphocytes. Chromium (Cr) addition at a concentration of 5 microg showed an increase in cytotoxicity, apoptosis and reactive oxygen species (ROS) and a decrease in lymphocyte proliferation and antioxidant levels, whereas pre-treatment of the cells with P. tomentosa extract (at 500 microg concentration) resulted in decreased cytotoxicity and ROS levels. Further, the drug treatment also maintained antioxidant levels and restored lymphocyte proliferation similar to that of control cells. The results indicated that the leaf extract of P. tomentosa has cytoprotective and immunomodulatory activities."
1290226,Feng et al. 2003,Chromium(VI) exposure enhances polycyclic aromatic hydrocarbon-DNA binding at the p53 gene in human lung cells,"Chromium(VI) [Cr(VI)] is a ubiquitous environmental and industrial contaminant. Cr(VI) exposure is strongly associated with a higher incidence of human lung cancer, but the mechanism of Cr(VI) carcinogenicity remains unclear. Cigarette smoking has been known as the prominent cause of lung cancer, and polycyclic aromatic hydrocarbons (PAHs), the major carcinogens in cigarette smoke, have been suggested as being responsible for the initiation and development of lung cancer. It has been reported that lung cancer from workers exposed to Cr(VI) has a high percentage of G to T transversion mutations in the non-transcribed strand of the p53 gene, a hallmark of PAH-induced mutation. Cr(VI) is a weak mutagen although it can induce a high percentage of G to T transversion mutations. These results raise the possibility that Cr(VI) may enhance PAH binding at the p53 gene in lung tissue. To test this possibility, we have determined the effect of Cr(VI) exposure on benzo[a]pyrene diol epoxides (BPDE)-DNA binding at total genomic DNA level and at the p53 gene in normal human lung fibroblast cells. We found that in lung cells Cr(VI) pre-exposure does not affect the BPDE-DNA binding at the total genomic DNA level or at exons 5, 6 and 9 of the p53 gene; however, it greatly enhances BPDE-DNA binding at exons 7 and 8 of the p53 gene, especially at mutational hotspots of lung cancer: codons 248, 273 and 282 of the p53 gene. No enhancement of BPDE-DNA binding in the p53 was observed when naked genomic DNA isolated from Cr(VI)-exposed cells was modified with BPDE in vitro. These results suggest that Cr(VI) exposure may enhance chromatin structure-dependent carcinogen-DNA binding. This effect may contribute to the synergism of Cr(VI) and BPDE on mutagenesis and cell transformation, and may also contribute to the higher incidence of lung cancer in Cr(VI)-exposed populations.","Chromium(VI) exposure enhances polycyclic aromatic hydrocarbon-DNA binding at the p53 gene in human lung cells Abs: Chromium(VI) [Cr(VI)] is a ubiquitous environmental and industrial contaminant. Cr(VI) exposure is strongly associated with a higher incidence of human lung cancer, but the mechanism of Cr(VI) carcinogenicity remains unclear. Cigarette smoking has been known as the prominent cause of lung cancer, and polycyclic aromatic hydrocarbons (PAHs), the major carcinogens in cigarette smoke, have been suggested as being responsible for the initiation and development of lung cancer. It has been reported that lung cancer from workers exposed to Cr(VI) has a high percentage of G to T transversion mutations in the non-transcribed strand of the p53 gene, a hallmark of PAH-induced mutation. Cr(VI) is a weak mutagen although it can induce a high percentage of G to T transversion mutations. These results raise the possibility that Cr(VI) may enhance PAH binding at the p53 gene in lung tissue. To test this possibility, we have determined the effect of Cr(VI) exposure on benzo[a]pyrene diol epoxides (BPDE)-DNA binding at total genomic DNA level and at the p53 gene in normal human lung fibroblast cells. We found that in lung cells Cr(VI) pre-exposure does not affect the BPDE-DNA binding at the total genomic DNA level or at exons 5, 6 and 9 of the p53 gene; however, it greatly enhances BPDE-DNA binding at exons 7 and 8 of the p53 gene, especially at mutational hotspots of lung cancer: codons 248, 273 and 282 of the p53 gene. No enhancement of BPDE-DNA binding in the p53 was observed when naked genomic DNA isolated from Cr(VI)-exposed cells was modified with BPDE in vitro. These results suggest that Cr(VI) exposure may enhance chromatin structure-dependent carcinogen-DNA binding. This effect may contribute to the synergism of Cr(VI) and BPDE on mutagenesis and cell transformation, and may also contribute to the higher incidence of lung cancer in Cr(VI)-exposed populations."
1290225,Sai Ram et al. 2003,Cytoprotective activity of Amla (Emblica officinalis) against chromium (VI) induced oxidative injury in murine macrophages,"The cytoprotective and immunomodulating properties of Emblica officinalis (Amla) against chromium (VI) induced oxidative damage are reported. Chromium (VI) at 1 micro g/mL concentration was highly cytotoxic. It enhanced free radical production and decreased reduced glutathione (GSH) levels and glutathione peroxidase (GPx) activity in macrophages. The presence of Amla resulted in an enhanced cell survival, decreased free radical production and higher antioxidant levels similar to that of control cells. Further, chromium (VI) treatment resulted in decreased phagocytosis and gamma-interferon (gamma-IFN) production while Amla inhibited chromium induced immunosuppression and restored both phagocytosis and gamma-IFN production by macrophages significantly.","Cytoprotective activity of Amla (Emblica officinalis) against chromium (VI) induced oxidative injury in murine macrophages Abs: The cytoprotective and immunomodulating properties of Emblica officinalis (Amla) against chromium (VI) induced oxidative damage are reported. Chromium (VI) at 1 micro g/mL concentration was highly cytotoxic. It enhanced free radical production and decreased reduced glutathione (GSH) levels and glutathione peroxidase (GPx) activity in macrophages. The presence of Amla resulted in an enhanced cell survival, decreased free radical production and higher antioxidant levels similar to that of control cells. Further, chromium (VI) treatment resulted in decreased phagocytosis and gamma-interferon (gamma-IFN) production while Amla inhibited chromium induced immunosuppression and restored both phagocytosis and gamma-IFN production by macrophages significantly."
1290224,Majumder et al. 2003,"Chromium(VI) down-regulates heavy metal-induced metallothionein gene transcription by modifying transactivation potential of the key transcription factor, metal-responsive transcription factor 1","The robust induction of metallothionein-I and II (MT-I and MT-II) genes by several heavy metals such as zinc and cadmium requires the specific transcription factor metal-responsive transcription factor 1 (MTF1). Chromium (VI), a major environmental carcinogen, not only failed to activate these genes but also inhibited their induction by Zn2+ or Cd2+. The heavy metal-induced expression of another MTF1 target gene, zinc transporter 1 (ZnT-1), was also down-regulated by Cr6+. By contrast, the expression of two MTF1-independent Cd2+-inducible genes, heme oxygenase 1 (HO-1) and HSP-70, was not sensitive to Cr6+. Cr6+ did not also affect the expression of housekeeping genes such as GAPDH or beta-actin. Stable cell lines overexpressing variable levels of MTF1, the key transactivator of the MT genes, demonstrated differential resistance toward the inhibitory effect of Cr6+, indicating MTF1 as a target of chromium toxicity. The basal and inducible binding of MTF1 to metal response elements was not affected by treatment of cells with Cr6+. Transient transfection studies showed that the ability of MTF1 to transactivate the MT-I promoter was significantly compromised by Cr6+. The fusion protein consisting of a Gal-4 DNA binding domain and one or more of the three transactivation domains of MTF1, namely the acidic domain, proline-rich domain, and serine-threonine rich domain, activated the GAL-4-driven luciferase gene to different degrees, but all were sensitive to Cr6+. MTF1 null cells were prone to apoptosis after exposure to Zn2+ or Cd2+ that was augmented in presence Cr6+, whereas the onset of apoptosis was significantly delayed in cells overexpressing MTF1.","Chromium(VI) down-regulates heavy metal-induced metallothionein gene transcription by modifying transactivation potential of the key transcription factor, metal-responsive transcription factor 1 Abs: The robust induction of metallothionein-I and II (MT-I and MT-II) genes by several heavy metals such as zinc and cadmium requires the specific transcription factor metal-responsive transcription factor 1 (MTF1). Chromium (VI), a major environmental carcinogen, not only failed to activate these genes but also inhibited their induction by Zn2+ or Cd2+. The heavy metal-induced expression of another MTF1 target gene, zinc transporter 1 (ZnT-1), was also down-regulated by Cr6+. By contrast, the expression of two MTF1-independent Cd2+-inducible genes, heme oxygenase 1 (HO-1) and HSP-70, was not sensitive to Cr6+. Cr6+ did not also affect the expression of housekeeping genes such as GAPDH or beta-actin. Stable cell lines overexpressing variable levels of MTF1, the key transactivator of the MT genes, demonstrated differential resistance toward the inhibitory effect of Cr6+, indicating MTF1 as a target of chromium toxicity. The basal and inducible binding of MTF1 to metal response elements was not affected by treatment of cells with Cr6+. Transient transfection studies showed that the ability of MTF1 to transactivate the MT-I promoter was significantly compromised by Cr6+. The fusion protein consisting of a Gal-4 DNA binding domain and one or more of the three transactivation domains of MTF1, namely the acidic domain, proline-rich domain, and serine-threonine rich domain, activated the GAL-4-driven luciferase gene to different degrees, but all were sensitive to Cr6+. MTF1 null cells were prone to apoptosis after exposure to Zn2+ or Cd2+ that was augmented in presence Cr6+, whereas the onset of apoptosis was significantly delayed in cells overexpressing MTF1."
1290223,Codd et al. 2003,Sialoglycoprotein and carbohydrate complexes in chromium toxicity,"Chromium(VI) compounds are amongst the most widely encountered industrial carcinogens and are of increasing concern with respect to environmental exposure. Sialoglycoproteins and carbohydrates play a crucial role in stabilizing oxoCr(V) intermediates, which are produced by extracellular and intracellular reduction of chromium(VI). Recent research has addressed the molecular characterization of oxoCr(V)-sialoglycoprotein and -carbohydrate complexes and the roles that these species may play in Cr(VI) metabolism and carcinogenesis. Particular highlights include the role of oxoCr(V) complexes of extracellular sialoglycoproteins, intracellular D-glucose, and related species and their potential roles in Cr(VI)-induced genotoxicity.","Sialoglycoprotein and carbohydrate complexes in chromium toxicity Abs: Chromium(VI) compounds are amongst the most widely encountered industrial carcinogens and are of increasing concern with respect to environmental exposure. Sialoglycoproteins and carbohydrates play a crucial role in stabilizing oxoCr(V) intermediates, which are produced by extracellular and intracellular reduction of chromium(VI). Recent research has addressed the molecular characterization of oxoCr(V)-sialoglycoprotein and -carbohydrate complexes and the roles that these species may play in Cr(VI) metabolism and carcinogenesis. Particular highlights include the role of oxoCr(V) complexes of extracellular sialoglycoproteins, intracellular D-glucose, and related species and their potential roles in Cr(VI)-induced genotoxicity."
1290222,Cruces et al. 2003,Evidence suggesting that chlorophyllin (CHLN) may act as an inhibitor or a promoter of genetic damage induced by chromium(VI) oxide (CrO3) in somatic cells of Drosophila,"In Drosophila, 48h-old larvae were pretreated for 24h with chlorophyllin (CHLN) or sucrose and then treated with chromium(VI) oxide (CrO(3)) immediately following completion of the pretreatment period (0-day delay) or delayed 1, 2 or 3 days. The effects were scored in the wing spot test. After delays of 0 and 1 day, clear evidence of a protective effect of CHLN was found. Contrarily, after delays of 2 and 3 days, the results showed a reversal, i.e. CHLN-related events appeared more frequently than those in the sucrose control suggesting a promoting effect. It would appear prudent that CHLN be tested in a variety of situations in any given organism before decisions are reached regarding its inhibitor/promoter effects.","Evidence suggesting that chlorophyllin (CHLN) may act as an inhibitor or a promoter of genetic damage induced by chromium(VI) oxide (CrO3) in somatic cells of Drosophila Abs: In Drosophila, 48h-old larvae were pretreated for 24h with chlorophyllin (CHLN) or sucrose and then treated with chromium(VI) oxide (CrO(3)) immediately following completion of the pretreatment period (0-day delay) or delayed 1, 2 or 3 days. The effects were scored in the wing spot test. After delays of 0 and 1 day, clear evidence of a protective effect of CHLN was found. Contrarily, after delays of 2 and 3 days, the results showed a reversal, i.e. CHLN-related events appeared more frequently than those in the sucrose control suggesting a promoting effect. It would appear prudent that CHLN be tested in a variety of situations in any given organism before decisions are reached regarding its inhibitor/promoter effects."
1290220,Shrivastava et al. 2002,Effects of chromium on the immune system,"Chromium is a naturally occurring heavy metal found commonly in the environment in trivalent, Cr(III), and hexavalent, Cr(VI), forms. Cr(VI) compounds have been declared as a potent occupational carcinogen among workers in chrome plating, stainless steel, and pigment industries. The reduction of Cr(VI) to Cr(III) results in the formation of reactive intermediates that together with oxidative stress oxidative tissue damage and a cascade of cellular events including modulation of apoptosis regulatory gene p53, contribute to the cytotoxicity, genotoxicity and carcinogenicity of Cr(VI)-containing compounds. On the other hand, chromium is an essential nutrient required to promote the action of insulin in body tissues so that the body can use sugars, proteins and fats. Chromium is of significant importance in altering the immune response by immunostimulatory or immunosuppressive processes as shown by its effects on T and B lymphocytes, macrophages, cytokine production and the immune response that may induce hypersensitivity reactions. This review gives an overview of the effects of chromium on the immune system of the body.","Effects of chromium on the immune system Abs: Chromium is a naturally occurring heavy metal found commonly in the environment in trivalent, Cr(III), and hexavalent, Cr(VI), forms. Cr(VI) compounds have been declared as a potent occupational carcinogen among workers in chrome plating, stainless steel, and pigment industries. The reduction of Cr(VI) to Cr(III) results in the formation of reactive intermediates that together with oxidative stress oxidative tissue damage and a cascade of cellular events including modulation of apoptosis regulatory gene p53, contribute to the cytotoxicity, genotoxicity and carcinogenicity of Cr(VI)-containing compounds. On the other hand, chromium is an essential nutrient required to promote the action of insulin in body tissues so that the body can use sugars, proteins and fats. Chromium is of significant importance in altering the immune response by immunostimulatory or immunosuppressive processes as shown by its effects on T and B lymphocytes, macrophages, cytokine production and the immune response that may induce hypersensitivity reactions. This review gives an overview of the effects of chromium on the immune system of the body."
1290219,Cohen et al. 2002,Rapid communication: effect of inhaled chromium on pulmonary A1AT,"A major health hazard to coal miners is development of emphysema following long-term exposure to coal dust. One mechanism underlying development of emphysema is the oxidation of critical methionine (Met) residues in antiproteolytic factor, alpha1-antitrypsin (A1AT) resulting in a protease-antiprotease imbalance in the lung. Several studies have documented an association between the incidence and severity of emphysema among miners and their exposure to crystalline silica (i.e., SiO(2)). However, what remains unclear is the role of other co-inhaled nonemphysematogenic nonoxidant inorganic constituent in disease pathogenesis. We hypothesize that in miners, inhaled trivalent chromium (Cr(3+), the only form of Cr in coal) may potentially affect lung A1AT activity in situ via Cr complexing with Met residues, and thereby exacerbate any SiO(2)-induced imbalance. To ascertain if Cr(3+) could, in fact, affect A1AT activity, in vitro studies were done to assess elastase inhibitory activity following A1AT incubation with soluble Cr(3+). In addition, to determine if Cr(3+) found in the lungs as detoxification products of inhaled hexavalent Cr (Cr(6+)) could affect A1AT in situ, lavages from the lungs of chromate-exposed rats were also analyzed for elastase inhibitory activity The in vitro results indicate that Cr(3+) ions clearly inhibited A1AT function, with an IC50 of 1.1 mM being estimated under the experimental conditions used. The in vivo results indicate that long-term inhalation (12 wk or longer) of chromate-bearing atmospheres also gave rise to significant (i.e., 50-70%) inhibition of the antielastase activity of A1AT. Together, these results clearly suggest that the Cr(3+) present in coal dusts could potentially act to inhibit A1AT activity in the lungs of miners and thereby promote the emphysematogenicity of SiO(2) or of other emphysematogens present as coconstituents in these dusts.","Rapid communication: effect of inhaled chromium on pulmonary A1AT Abs: A major health hazard to coal miners is development of emphysema following long-term exposure to coal dust. One mechanism underlying development of emphysema is the oxidation of critical methionine (Met) residues in antiproteolytic factor, alpha1-antitrypsin (A1AT) resulting in a protease-antiprotease imbalance in the lung. Several studies have documented an association between the incidence and severity of emphysema among miners and their exposure to crystalline silica (i.e., SiO(2)). However, what remains unclear is the role of other co-inhaled nonemphysematogenic nonoxidant inorganic constituent in disease pathogenesis. We hypothesize that in miners, inhaled trivalent chromium (Cr(3+), the only form of Cr in coal) may potentially affect lung A1AT activity in situ via Cr complexing with Met residues, and thereby exacerbate any SiO(2)-induced imbalance. To ascertain if Cr(3+) could, in fact, affect A1AT activity, in vitro studies were done to assess elastase inhibitory activity following A1AT incubation with soluble Cr(3+). In addition, to determine if Cr(3+) found in the lungs as detoxification products of inhaled hexavalent Cr (Cr(6+)) could affect A1AT in situ, lavages from the lungs of chromate-exposed rats were also analyzed for elastase inhibitory activity The in vitro results indicate that Cr(3+) ions clearly inhibited A1AT function, with an IC50 of 1.1 mM being estimated under the experimental conditions used. The in vivo results indicate that long-term inhalation (12 wk or longer) of chromate-bearing atmospheres also gave rise to significant (i.e., 50-70%) inhibition of the antielastase activity of A1AT. Together, these results clearly suggest that the Cr(3+) present in coal dusts could potentially act to inhibit A1AT activity in the lungs of miners and thereby promote the emphysematogenicity of SiO(2) or of other emphysematogens present as coconstituents in these dusts."
1290218,Dillon et al. 2002,Hard X-ray microprobe studies of chromium(VI)-treated V79 Chinese hamster lung cells: intracellular mapping of the biotransformation products of a chromium carcinogen,"The uptake of carcinogenic and mutagenic Cr compounds and the intracellular distribution of their biotransformation products in V79 Chinese hamster lung cells were studied by synchrotron-radiation-induced X-ray emission (SRIXE). SRIXE analysis was performed on whole cells that had been treated with either Cr(III) or Cr(V) 1,10-phenanthroline complexes, or Cr(VI). The high spatial resolution (0.3 microm) and elemental sensitivity (~10(-15) g Cr/cell) of the technique provided detailed maps of Cr and other cellular elements in thin sections prepared from Cr(VI)-treated cells. The Cr carcinogen concentrated in P-rich regions corresponding to the nucleus, as well as other areas of the cell that are likely to correspond to organelles. This is the first study that has enabled the determination of the localization of the biotransformation products of Cr(VI) carcinogens in a target lung cell.","Hard X-ray microprobe studies of chromium(VI)-treated V79 Chinese hamster lung cells: intracellular mapping of the biotransformation products of a chromium carcinogen Abs: The uptake of carcinogenic and mutagenic Cr compounds and the intracellular distribution of their biotransformation products in V79 Chinese hamster lung cells were studied by synchrotron-radiation-induced X-ray emission (SRIXE). SRIXE analysis was performed on whole cells that had been treated with either Cr(III) or Cr(V) 1,10-phenanthroline complexes, or Cr(VI). The high spatial resolution (0.3 microm) and elemental sensitivity (~10(-15) g Cr/cell) of the technique provided detailed maps of Cr and other cellular elements in thin sections prepared from Cr(VI)-treated cells. The Cr carcinogen concentrated in P-rich regions corresponding to the nucleus, as well as other areas of the cell that are likely to correspond to organelles. This is the first study that has enabled the determination of the localization of the biotransformation products of Cr(VI) carcinogens in a target lung cell."
1290217,Sai Ram et al. 2002,Cyto-protective and immunomodulating properties of Amla (Emblica officinalis) on lymphocytes: an in-vitro study,"The fruits extracts of Emblica officinalis (Amla) has been reported to have strong anti-oxidant properties. There is a paucity of studies on the immunomodulatory properties of fruit extracts of Amla in immuno-compromised states, with the emphasis on lymphocytes. Therefore, the aim of the study was to determine the anti-oxidant and immunomodulatory properties of Amla using chromium (VI) as an immunosuppressive agent. Chromium (Cr) treatment results in enhanced cytotoxicity, free radical production, lipid peroxidation and decreased glutathione peroxidase (GPx) activity and diminished glutathione (GSH) levels. There was a significant inhibition of both lipopolysaccharide and concanavalin-A-stimulated lymphocyte proliferation. Chromium also inhibited Con A stimulated interleukin-2 and gamma-interferon production significantly. Further, there was enhanced apoptosis and DNA fragmentation in the presence of Cr. Amla significantly inhibited Cr-induced free radical production and restored the anti-oxidant status back to control level. Amla also inhibited apoptosis and DNA fragmentation induced by Cr. Interestingly, Amla relieved the immunosuppressive effects of Cr on lymphocyte proliferation and even restored the IL-2 and gamma-IFN production considerably.","Cyto-protective and immunomodulating properties of Amla (Emblica officinalis) on lymphocytes: an in-vitro study Abs: The fruits extracts of Emblica officinalis (Amla) has been reported to have strong anti-oxidant properties. There is a paucity of studies on the immunomodulatory properties of fruit extracts of Amla in immuno-compromised states, with the emphasis on lymphocytes. Therefore, the aim of the study was to determine the anti-oxidant and immunomodulatory properties of Amla using chromium (VI) as an immunosuppressive agent. Chromium (Cr) treatment results in enhanced cytotoxicity, free radical production, lipid peroxidation and decreased glutathione peroxidase (GPx) activity and diminished glutathione (GSH) levels. There was a significant inhibition of both lipopolysaccharide and concanavalin-A-stimulated lymphocyte proliferation. Chromium also inhibited Con A stimulated interleukin-2 and gamma-interferon production significantly. Further, there was enhanced apoptosis and DNA fragmentation in the presence of Cr. Amla significantly inhibited Cr-induced free radical production and restored the anti-oxidant status back to control level. Amla also inhibited apoptosis and DNA fragmentation induced by Cr. Interestingly, Amla relieved the immunosuppressive effects of Cr on lymphocyte proliferation and even restored the IL-2 and gamma-IFN production considerably."
1290216,Kawanishi et al. 2002,The role of metals in site-specific DNA damage with reference to carcinogenesis,"We reviewed the mechanism of oxidative DNA damage with reference to metal carcinogenesis and metal-mediated chemical carcinogenesis. On the basis of the finding that chromium (VI) induced oxidative DNA damage in the presence of hydrogen peroxide (H2O2), we proposed the hypothesis that endogenous reactive oxygen species play a role in metal carcinogenesis. Since then, we have reported that various metal compounds, such as cobalt, nickel, and ferric nitrilotriacetate, directly cause site-specific DNA damage in the presence of H2O2. We also found that carcinogenic metals could cause DNA damage through indirect mechanisms. Certain nickel compounds induced oxidative DNA damage in rat lungs through inflammation. Endogenous metals, copper and iron, catalyzed ROS generation from various organic carcinogens, resulting in oxidative DNA damage. Polynuclear compounds, such as 4-aminobiphenyl and heterocyclic amines, appear to induce cancer mainly through DNA adduct formation, although their N-hydroxy and nitroso metabolites can also cause oxidative DNA damage. On the other hand, mononuclear compounds, such as benzene metabolites, caffeic acid, and o-toluidine, should express their carcionogenicity through oxidative DNA damage. Metabolites of certain carcinogens efficiently caused oxidative DNA damage by forming NADH-dependent redox cycles. These findings suggest that metal-mediated oxidative DNA damage plays important roles in chemical carcinogenesis.","The role of metals in site-specific DNA damage with reference to carcinogenesis Abs: We reviewed the mechanism of oxidative DNA damage with reference to metal carcinogenesis and metal-mediated chemical carcinogenesis. On the basis of the finding that chromium (VI) induced oxidative DNA damage in the presence of hydrogen peroxide (H2O2), we proposed the hypothesis that endogenous reactive oxygen species play a role in metal carcinogenesis. Since then, we have reported that various metal compounds, such as cobalt, nickel, and ferric nitrilotriacetate, directly cause site-specific DNA damage in the presence of H2O2. We also found that carcinogenic metals could cause DNA damage through indirect mechanisms. Certain nickel compounds induced oxidative DNA damage in rat lungs through inflammation. Endogenous metals, copper and iron, catalyzed ROS generation from various organic carcinogens, resulting in oxidative DNA damage. Polynuclear compounds, such as 4-aminobiphenyl and heterocyclic amines, appear to induce cancer mainly through DNA adduct formation, although their N-hydroxy and nitroso metabolites can also cause oxidative DNA damage. On the other hand, mononuclear compounds, such as benzene metabolites, caffeic acid, and o-toluidine, should express their carcionogenicity through oxidative DNA damage. Metabolites of certain carcinogens efficiently caused oxidative DNA damage by forming NADH-dependent redox cycles. These findings suggest that metal-mediated oxidative DNA damage plays important roles in chemical carcinogenesis."
1290215,Quievryn et al. 2002,Carcinogenic chromium(VI) induces cross-linking of vitamin C to DNA in vitro and in human lung A549 cells,"Reductive activation of carcinogenic Cr(VI) is required for the induction of DNA damage and mutations. Here, we examined the formation of Cr-DNA adducts in the reactions of Cr(VI) with its dominant biological reducer, vitamin C (ascorbate). Reductive conversion of Cr(VI) to Cr(III) by ascorbate produced stable Cr-DNA adducts, of which approximately 25% constituted ascorbate-Cr(III)-DNA cross-links. No evidence was found for the involvement of Cr(V) or Cr(IV) intermediates in the formation of either binary or ternary adducts. The cross-linking reaction was consistent with the attack of DNA by transient Cr(III)-ascorbate complexes. The yield of Cr(III)-DNA adducts was similar on dsDNA and AGT, ACT, or CT oligonucleotides and was strongly inhibited by Mg(2+), suggesting predominant coordination of Cr(III) to DNA phosphate oxygens. We also detected cross-linking of ascorbate to DNA in Cr(VI)-exposed human lung A549 cells that were preincubated with dehydroascorbic acid to create normal levels of intracellular ascorbate. Ascorbate-Cr-DNA cross-links accounted for approximately 6% of the total Cr-DNA adducts in A549 cells. Shuttle-vector experiments showed that ascorbate-Cr-DNA cross-links were mutagenic in human cells. Our results demonstrate that in addition to reduction of Cr(VI) to DNA-reactive Cr(III), vitamin C contributes to the genotoxicity of Cr(VI) via a direct chemical modification of DNA. The absence of Asc in A549 and other human cultured cells indicates that cells maintained under the usual in vitro conditions lack the most important reducing agent for Cr(VI) and would primarily display slow thiol-dependent activation of Cr(VI).","Carcinogenic chromium(VI) induces cross-linking of vitamin C to DNA in vitro and in human lung A549 cells Abs: Reductive activation of carcinogenic Cr(VI) is required for the induction of DNA damage and mutations. Here, we examined the formation of Cr-DNA adducts in the reactions of Cr(VI) with its dominant biological reducer, vitamin C (ascorbate). Reductive conversion of Cr(VI) to Cr(III) by ascorbate produced stable Cr-DNA adducts, of which approximately 25% constituted ascorbate-Cr(III)-DNA cross-links. No evidence was found for the involvement of Cr(V) or Cr(IV) intermediates in the formation of either binary or ternary adducts. The cross-linking reaction was consistent with the attack of DNA by transient Cr(III)-ascorbate complexes. The yield of Cr(III)-DNA adducts was similar on dsDNA and AGT, ACT, or CT oligonucleotides and was strongly inhibited by Mg(2+), suggesting predominant coordination of Cr(III) to DNA phosphate oxygens. We also detected cross-linking of ascorbate to DNA in Cr(VI)-exposed human lung A549 cells that were preincubated with dehydroascorbic acid to create normal levels of intracellular ascorbate. Ascorbate-Cr-DNA cross-links accounted for approximately 6% of the total Cr-DNA adducts in A549 cells. Shuttle-vector experiments showed that ascorbate-Cr-DNA cross-links were mutagenic in human cells. Our results demonstrate that in addition to reduction of Cr(VI) to DNA-reactive Cr(III), vitamin C contributes to the genotoxicity of Cr(VI) via a direct chemical modification of DNA. The absence of Asc in A549 and other human cultured cells indicates that cells maintained under the usual in vitro conditions lack the most important reducing agent for Cr(VI) and would primarily display slow thiol-dependent activation of Cr(VI)."
1290214,Dayan and  Paine 2001,"Mechanisms of chromium toxicity, carcinogenicity and allergenicity: review of the literature from 1985 to 2000","Laboratory and clinical reports about the pathogenesis of the carcinogenicity and allergenicity of chromium compounds published between 1985 and 2000 have been reviewed as a basis for consideration of the pathogenetic mechanisms involved. There is good evidence from the clinic and the laboratory that Cr[VI] is the ion responsible for most of the toxic actions, although much of the underlying molecular damage may be due to its intracellular reduction to the even more highly reactive and short-lived chemical species Cr[III] and Cr[V]. Exposure to Cr[VI] can result in various point mutations in DNA and to chromosomal damage, as well as to oxidative changes in proteins and to adduct formation. The relative importance of these effects of chromium ions and of the free oxidising radicals they may generate in the body in causing tumours and allergic sensitisation remain to be demonstrated. Biochemical studies of the DNA-damaging effects and of the pathogenesis of the allergic reactions to chromium ions have not kept up with advances in understanding of the molecular basis of the effects of other carcinogens and allergens.","Mechanisms of chromium toxicity, carcinogenicity and allergenicity: review of the literature from 1985 to 2000 Abs: Laboratory and clinical reports about the pathogenesis of the carcinogenicity and allergenicity of chromium compounds published between 1985 and 2000 have been reviewed as a basis for consideration of the pathogenetic mechanisms involved. There is good evidence from the clinic and the laboratory that Cr[VI] is the ion responsible for most of the toxic actions, although much of the underlying molecular damage may be due to its intracellular reduction to the even more highly reactive and short-lived chemical species Cr[III] and Cr[V]. Exposure to Cr[VI] can result in various point mutations in DNA and to chromosomal damage, as well as to oxidative changes in proteins and to adduct formation. The relative importance of these effects of chromium ions and of the free oxidising radicals they may generate in the body in causing tumours and allergic sensitisation remain to be demonstrated. Biochemical studies of the DNA-damaging effects and of the pathogenesis of the allergic reactions to chromium ions have not kept up with advances in understanding of the molecular basis of the effects of other carcinogens and allergens."
1290213,Stearns et al. 2002,Chromium(III) tris(picolinate) is mutagenic at the hypoxanthine (guanine) phosphoribosyltransferase locus in Chinese hamster ovary cells,"Chromium trispicolinate (CrPic) is a popular dietary supplement that is not regulated by the Food and Drug Administration. We are using this compound as a bio-available model to explore the role of Cr(III) in Cr(VI)-induced cancers. The ability of CrPic to cause mutations at the hypoxanthine (guanine) phosphoribosyltransferase (hprt) locus of CHO AA8 cells has been measured after a 48 h exposure. The highest dose tested was 80 microg/cm(2) CrPic, which, if fully soluble, would be equivalent to 1mM or 0.44 mg/ml CrPic, and would correspond to 1mM Cr(III) or 52 microg/ml Cr(III). This exposure resulted in 68+/-16% cell survival based on 48 h cell counts, and 24+/-11% survival by 7-day colony formation. Exposure of CHO cells to CrPic produced a statistically significant increase in 6-thioguanine (6-TG)-resistant cells over the dose range tested. The 80 microg/cm(2) CrPic exposure resulted in an average induced mutation frequency (MF) of 58 per 10(6) surviving cells, or an average 40-fold increase in hprt mutants relative to untreated cells. An equivalent dose of 3mM Pic was highly cytotoxic and did not yield hprt mutants. The dose range of 0.375-1.5mM Pic produced a slight increase in hprt mutants, but the increase was not statistically significant. An equivalent dose of 1mM chromic chloride yielded an induced MF of 9 per 10(6) surviving cells, or a 10-fold increase in mutants with cell survivals of &gt;100%. The coordination of Cr(III) with picolinic acid may make the metal more genotoxic than other forms of Cr(III). In light of the current results and the known ability of Cr(III) and CrPic to accumulate in tissues, as well as the growing evidence of Cr(III) involvement in Cr(VI)-induced cancers, we caution against ingestion of large doses of CrPic for extended periods.","Chromium(III) tris(picolinate) is mutagenic at the hypoxanthine (guanine) phosphoribosyltransferase locus in Chinese hamster ovary cells Abs: Chromium trispicolinate (CrPic) is a popular dietary supplement that is not regulated by the Food and Drug Administration. We are using this compound as a bio-available model to explore the role of Cr(III) in Cr(VI)-induced cancers. The ability of CrPic to cause mutations at the hypoxanthine (guanine) phosphoribosyltransferase (hprt) locus of CHO AA8 cells has been measured after a 48 h exposure. The highest dose tested was 80 microg/cm(2) CrPic, which, if fully soluble, would be equivalent to 1mM or 0.44 mg/ml CrPic, and would correspond to 1mM Cr(III) or 52 microg/ml Cr(III). This exposure resulted in 68+/-16% cell survival based on 48 h cell counts, and 24+/-11% survival by 7-day colony formation. Exposure of CHO cells to CrPic produced a statistically significant increase in 6-thioguanine (6-TG)-resistant cells over the dose range tested. The 80 microg/cm(2) CrPic exposure resulted in an average induced mutation frequency (MF) of 58 per 10(6) surviving cells, or an average 40-fold increase in hprt mutants relative to untreated cells. An equivalent dose of 3mM Pic was highly cytotoxic and did not yield hprt mutants. The dose range of 0.375-1.5mM Pic produced a slight increase in hprt mutants, but the increase was not statistically significant. An equivalent dose of 1mM chromic chloride yielded an induced MF of 9 per 10(6) surviving cells, or a 10-fold increase in mutants with cell survivals of &gt;100%. The coordination of Cr(III) with picolinic acid may make the metal more genotoxic than other forms of Cr(III). In light of the current results and the known ability of Cr(III) and CrPic to accumulate in tissues, as well as the growing evidence of Cr(III) involvement in Cr(VI)-induced cancers, we caution against ingestion of large doses of CrPic for extended periods."
1290212,Codd and  Lay 2001,Chromium(V)-sialic (neuraminic) acid species are formed from mixtures of chromium(VI) and saliva,,Chromium(V)-sialic (neuraminic) acid species are formed from mixtures of chromium(VI) and saliva Abs: 
1290211,Levina et al. 2001,Disproportionation of a model chromium(V) complex causes extensive chromium(III)-DNA binding in vitro,"The first direct evidence for the role of Cr(V) complexes in the formation of potentially mutagenic Cr(III)-DNA adducts has been obtained. A model complex for the stabilized Cr(V) species formed in Cr(VI)-treated cells, [Cr(V)O(ehba)(2)]-[ehba = 2-ethyl-2-hydroxybutanoato(2-)], rapidly disproportionates in HEPES buffers at pH 7.4 [3 Cr(V) --&gt; 2 Cr(VI) + Cr(III)], and the formed Cr(III) species undergo efficient ionic binding to DNA, followed by slower covalent binding. The extent of Cr(III)-DNA binding significantly exceeds that caused by [Cr(III)(OH(2))(6)](3+) or by the Cr(III) products of Cr(VI) reductions under similar conditions. The Cr(III)-DNA binding can be dramatically reduced by the ability of the reaction medium (e.g., phosphate buffer) to form complexes with Cr(III) during and after the disproportionation reaction. A mechanism of Cr(III)-DNA binding caused by Cr(V) disproportionation has been proposed on the basis of stoichiometric and kinetic studies.","Disproportionation of a model chromium(V) complex causes extensive chromium(III)-DNA binding in vitro Abs: The first direct evidence for the role of Cr(V) complexes in the formation of potentially mutagenic Cr(III)-DNA adducts has been obtained. A model complex for the stabilized Cr(V) species formed in Cr(VI)-treated cells, [Cr(V)O(ehba)(2)]-[ehba = 2-ethyl-2-hydroxybutanoato(2-)], rapidly disproportionates in HEPES buffers at pH 7.4 [3 Cr(V) --&gt; 2 Cr(VI) + Cr(III)], and the formed Cr(III) species undergo efficient ionic binding to DNA, followed by slower covalent binding. The extent of Cr(III)-DNA binding significantly exceeds that caused by [Cr(III)(OH(2))(6)](3+) or by the Cr(III) products of Cr(VI) reductions under similar conditions. The Cr(III)-DNA binding can be dramatically reduced by the ability of the reaction medium (e.g., phosphate buffer) to form complexes with Cr(III) during and after the disproportionation reaction. A mechanism of Cr(III)-DNA binding caused by Cr(V) disproportionation has been proposed on the basis of stoichiometric and kinetic studies."
1290210,Wang and  Shi 2001,"Mechanisms of Cr(VI)-induced p53 activation: the role of phosphorylation, mdm2 and ERK","The present study investigated the molecular mechanisms of p53 activation induced by Cr(VI), using human lung epithelial A549 cells. Cr(VI) increased both protein level and transactivation ability of p53 protein. The activation of p53 is at the protein level instead of the transcriptional level. The degradation of p53 was dramatically decreased upon stimulation by Cr(VI). In addition, Cr(VI) treatment decreased the interaction of p53 with mdm2 protooncoprotein, which blocks the transactivation ability of p53 and promotes the degradation of p53 protein. In response to Cr(VI) treatment, p53 protein became phosphorylated and acetylated at Ser15 and Lys382, respectively. The phosphorylation levels at either Ser20 or Ser392 did not show any significant alterations. Since previous studies report that it is Ser20 and not Ser15 phosphorylation that contributes to mdm2 dissociation from p53, the results obtained from the current investigation suggest a different mechanism: Ser15 instead of Ser20 may play a key role in the dissociation of mdm2 in response to Cr(VI). Erk, a member of mitogen-activated protein kinase, acts as the upstream kinase for the phosphorylation of the p53 Ser15 site.","Mechanisms of Cr(VI)-induced p53 activation: the role of phosphorylation, mdm2 and ERK Abs: The present study investigated the molecular mechanisms of p53 activation induced by Cr(VI), using human lung epithelial A549 cells. Cr(VI) increased both protein level and transactivation ability of p53 protein. The activation of p53 is at the protein level instead of the transcriptional level. The degradation of p53 was dramatically decreased upon stimulation by Cr(VI). In addition, Cr(VI) treatment decreased the interaction of p53 with mdm2 protooncoprotein, which blocks the transactivation ability of p53 and promotes the degradation of p53 protein. In response to Cr(VI) treatment, p53 protein became phosphorylated and acetylated at Ser15 and Lys382, respectively. The phosphorylation levels at either Ser20 or Ser392 did not show any significant alterations. Since previous studies report that it is Ser20 and not Ser15 phosphorylation that contributes to mdm2 dissociation from p53, the results obtained from the current investigation suggest a different mechanism: Ser15 instead of Ser20 may play a key role in the dissociation of mdm2 in response to Cr(VI). Erk, a member of mitogen-activated protein kinase, acts as the upstream kinase for the phosphorylation of the p53 Ser15 site."
1290209,Gunaratnam and  Grant 2001,The role of glutathione reductase in the cytotoxicity of chromium (VI) in isolated rat hepatocytes,"Chromium (VI) is an environmental and occupational carcinogen, and it is accepted that intracellular reduction is necessary for DNA damage and cytotoxicity. We have investigated the interaction of Cr(VI) with hepatocytes in vitro to determine the contribution of various hepatic enzymes to the reduction of Cr(VI). Cr(VI) caused a dose-dependent decrease in cell viability and intracellular reduced glutathione (GSH) levels between 100 and 500 microM within 3 h exposure of hepatocytes. Both DT-diaphorase and cytochrome P450 play only a minor role in detoxifying Cr(VI) and/or its metabolites. (GSH) appears to act as a non-enzymatic reductant, reducing Cr(VI) to a toxic form. The evidence for this is two-fold. Firstly, GSH was depleted during the metabolism of Cr(VI) and, secondly, pretreatment of the cells with diethylmaleate to deplete GSH levels, partially protected the cells from Cr(VI) toxicity. Glutathione reductase appears to play an important role in the enzymatic reduction of Cr(VI) as inhibition of this enzyme by carmustine (BCNU) markedly protected the cells from cytotoxicity.","The role of glutathione reductase in the cytotoxicity of chromium (VI) in isolated rat hepatocytes Abs: Chromium (VI) is an environmental and occupational carcinogen, and it is accepted that intracellular reduction is necessary for DNA damage and cytotoxicity. We have investigated the interaction of Cr(VI) with hepatocytes in vitro to determine the contribution of various hepatic enzymes to the reduction of Cr(VI). Cr(VI) caused a dose-dependent decrease in cell viability and intracellular reduced glutathione (GSH) levels between 100 and 500 microM within 3 h exposure of hepatocytes. Both DT-diaphorase and cytochrome P450 play only a minor role in detoxifying Cr(VI) and/or its metabolites. (GSH) appears to act as a non-enzymatic reductant, reducing Cr(VI) to a toxic form. The evidence for this is two-fold. Firstly, GSH was depleted during the metabolism of Cr(VI) and, secondly, pretreatment of the cells with diethylmaleate to deplete GSH levels, partially protected the cells from Cr(VI) toxicity. Glutathione reductase appears to play an important role in the enzymatic reduction of Cr(VI) as inhibition of this enzyme by carmustine (BCNU) markedly protected the cells from cytotoxicity."
1290208,D'Agostini et al. 2000,Interactions between N-acetylcysteine and ascorbic acid in modulating mutagenesis and carcinogenesis,"Both ascorbic acid (AsA, vitamin C) and N-acetylcysteine (NAC), a precursor and analogue of glutathione, possess a broad array of biological properties underlying their protective role in a variety of pathophysiological conditions. However, under certain circumstances, AsA behaves as a pro-oxidant rather than an anti-oxidant and produces adverse effects. This prompted us to evaluate whether NAC could interact with AsA in preventing mutation and cancer. AsA significantly increased spontaneous revertants in the Salmonella typhimurium strains TA102 and TA104, which are sensitive to oxidative mutagens. In contrast, NAC lowered the spontaneous background in TA104 and neutralized the negative effects of AsA. Moreover, NAC and AsA showed additive effects in reducing chromium(VI) and in reverting its mutagenicity. A single i.p. injection of urethane (1 g/kg body weight) to 120 A/J mice resulted, after 4 months, in the formation of a total of 1,532 lung tumors, 425 in the 30 mice treated with the carcinogen only, 404 in those treated with urethane plus AsA, 365 in those treated with urethane plus NAC and 338 in those treated with urethane plus the combination of AsA and NAC (both given daily with drinking water at the dose of 1 g/kg body weight). Compared to positive controls, tumor multiplicity was poorly affected by AsA, whereas it was significantly decreased by NAC and even more so by its combination with AsA. The overall volumes of lung tumors in the 4 groups were 107.5, 89.3, 61.3 and 49.7 mm(3), respectively. Tumor sizes were slightly but significantly decreased in mice treated with AsA and more so in those treated with NAC and NAC plus AsA, their combination being significantly more effective than each individually. All protective effects elicited by combining the 2 drugs were additive. Therefore, NAC prevents the adverse effects of AsA on spontaneous mutagenicity; at the same time, this thiol behaves in an additive fashion with AsA, inhibiting the mutagenicity of chromium(VI) and the lung tumorigenicity of urethane in mice. These findings suggest that NAC and AsA could conveniently be combined in cancer chemoprevention and other pharmacological interventions.","Interactions between N-acetylcysteine and ascorbic acid in modulating mutagenesis and carcinogenesis Abs: Both ascorbic acid (AsA, vitamin C) and N-acetylcysteine (NAC), a precursor and analogue of glutathione, possess a broad array of biological properties underlying their protective role in a variety of pathophysiological conditions. However, under certain circumstances, AsA behaves as a pro-oxidant rather than an anti-oxidant and produces adverse effects. This prompted us to evaluate whether NAC could interact with AsA in preventing mutation and cancer. AsA significantly increased spontaneous revertants in the Salmonella typhimurium strains TA102 and TA104, which are sensitive to oxidative mutagens. In contrast, NAC lowered the spontaneous background in TA104 and neutralized the negative effects of AsA. Moreover, NAC and AsA showed additive effects in reducing chromium(VI) and in reverting its mutagenicity. A single i.p. injection of urethane (1 g/kg body weight) to 120 A/J mice resulted, after 4 months, in the formation of a total of 1,532 lung tumors, 425 in the 30 mice treated with the carcinogen only, 404 in those treated with urethane plus AsA, 365 in those treated with urethane plus NAC and 338 in those treated with urethane plus the combination of AsA and NAC (both given daily with drinking water at the dose of 1 g/kg body weight). Compared to positive controls, tumor multiplicity was poorly affected by AsA, whereas it was significantly decreased by NAC and even more so by its combination with AsA. The overall volumes of lung tumors in the 4 groups were 107.5, 89.3, 61.3 and 49.7 mm(3), respectively. Tumor sizes were slightly but significantly decreased in mice treated with AsA and more so in those treated with NAC and NAC plus AsA, their combination being significantly more effective than each individually. All protective effects elicited by combining the 2 drugs were additive. Therefore, NAC prevents the adverse effects of AsA on spontaneous mutagenicity; at the same time, this thiol behaves in an additive fashion with AsA, inhibiting the mutagenicity of chromium(VI) and the lung tumorigenicity of urethane in mice. These findings suggest that NAC and AsA could conveniently be combined in cancer chemoprevention and other pharmacological interventions."
1290207,Pattison et al. 2000,An investigation into the genotoxic species generated during reduction of chromium(VI) by catechol(amine)s,"Chromium(VI) is a common occupational carcinogen.1 The major carcinogenic and mutagenic species are proposed to be Cr(V) and Cr(IV) intermediates formed during the reduction of Cr(VI) to stable Cr(III) compounds,2 although indirect evidence suggests that reactive oxygen species (ROS) may also be important.3 The reductions of Cr(VI) by some biological reductants (e.g. ascorbate) have been studied previously, and genotoxic Cr(IV/V) species have been detected.4 Another potential reductant in vivo is protein-bound DOPA, which is present on oxidised proteins at low steady-state concentrations prior to enzymatic breakdown.5 Recently, we have shown, by EPR spectroscopy, that the reactions of Cr(VI) with model DOPA compounds (catechol(amine)s), and with oxidised proteins themselves, generate several reactive intermediates, including Cr(V) complexes and organic radicals.6 Previous studies have proposed that ROS may also be produced during catechol(amine) oxidation.7 Here we describe studies of the interaction of DNA with the reactive species produced during the reductions of K2Cr2O7 by catechol(amine)s.","An investigation into the genotoxic species generated during reduction of chromium(VI) by catechol(amine)s Abs: Chromium(VI) is a common occupational carcinogen.1 The major carcinogenic and mutagenic species are proposed to be Cr(V) and Cr(IV) intermediates formed during the reduction of Cr(VI) to stable Cr(III) compounds,2 although indirect evidence suggests that reactive oxygen species (ROS) may also be important.3 The reductions of Cr(VI) by some biological reductants (e.g. ascorbate) have been studied previously, and genotoxic Cr(IV/V) species have been detected.4 Another potential reductant in vivo is protein-bound DOPA, which is present on oxidised proteins at low steady-state concentrations prior to enzymatic breakdown.5 Recently, we have shown, by EPR spectroscopy, that the reactions of Cr(VI) with model DOPA compounds (catechol(amine)s), and with oxidised proteins themselves, generate several reactive intermediates, including Cr(V) complexes and organic radicals.6 Previous studies have proposed that ROS may also be produced during catechol(amine) oxidation.7 Here we describe studies of the interaction of DNA with the reactive species produced during the reductions of K2Cr2O7 by catechol(amine)s."
1290206,Rowbotham et al. 2000,Chromium in the environment: an evaluation of exposure of the UK general population and possible adverse health effects,"Chromium in the hexavalent form, Cr(VI), has long been recognized as a carcinogen and there is concern as to the effects of continuous low-level exposure to chromium both occupationally and environmentally. This review summarizes the available exposure data and known health effects and evaluates the potential risk to human health in the United Kingdom. Chromium emissions to the environment in the United Kingdom are predominantly derived from fuel combustion, waste incineration, and industrial processes. The less toxic trivalent form of chromium [Cr(III)] is dominant in most environmental compartments, and any Cr(VI), the more toxic form, that is emitted to the environment can be reduced to Cr(III). Food is a major source of exposure to chromium, and estimated daily oral intakes for infants (1 yr), children (11 yr), and adults are 33-45, 123-171, and 246-343 micrograms/person/d, respectively. Soil ingestion, particularly common in young children, can contribute to oral intake. Inhalation is a minor route of exposure for the general population. Average daily inhalation intakes in infants can range from 0.004 microgram/d for rural infants to 0.14 microgram/d for urban infants who are passively exposed to tobacco smoke, whereas adults who live in industrialized areas and smoke may take up between 2 and 12 micrograms/d. The most serious health effect associated with Cr(VI) is lung cancer, which has been associated with some occupational exposure scenarios, whereas Cr(III) is an essential nutrient with a broad safety range and low toxicity. The human body has effective detoxification mechanisms that can reduce ingested or inhaled Cr(VI) to Cr(III). In conclusion, there is no clear evidence to relate exposure to environmental levels of chromium with adverse health effects in either the general UK population or subgroups exposed to chromium around industrialized or contaminated sites. It can be expected that an improved understanding of the relevance of possible long-term accumulation of Cr(III) in the body may facilitate a more complete assessment, in the future, of the health risks in the general population associated with environmental exposure to chromium.","Chromium in the environment: an evaluation of exposure of the UK general population and possible adverse health effects Abs: Chromium in the hexavalent form, Cr(VI), has long been recognized as a carcinogen and there is concern as to the effects of continuous low-level exposure to chromium both occupationally and environmentally. This review summarizes the available exposure data and known health effects and evaluates the potential risk to human health in the United Kingdom. Chromium emissions to the environment in the United Kingdom are predominantly derived from fuel combustion, waste incineration, and industrial processes. The less toxic trivalent form of chromium [Cr(III)] is dominant in most environmental compartments, and any Cr(VI), the more toxic form, that is emitted to the environment can be reduced to Cr(III). Food is a major source of exposure to chromium, and estimated daily oral intakes for infants (1 yr), children (11 yr), and adults are 33-45, 123-171, and 246-343 micrograms/person/d, respectively. Soil ingestion, particularly common in young children, can contribute to oral intake. Inhalation is a minor route of exposure for the general population. Average daily inhalation intakes in infants can range from 0.004 microgram/d for rural infants to 0.14 microgram/d for urban infants who are passively exposed to tobacco smoke, whereas adults who live in industrialized areas and smoke may take up between 2 and 12 micrograms/d. The most serious health effect associated with Cr(VI) is lung cancer, which has been associated with some occupational exposure scenarios, whereas Cr(III) is an essential nutrient with a broad safety range and low toxicity. The human body has effective detoxification mechanisms that can reduce ingested or inhaled Cr(VI) to Cr(III). In conclusion, there is no clear evidence to relate exposure to environmental levels of chromium with adverse health effects in either the general UK population or subgroups exposed to chromium around industrialized or contaminated sites. It can be expected that an improved understanding of the relevance of possible long-term accumulation of Cr(III) in the body may facilitate a more complete assessment, in the future, of the health risks in the general population associated with environmental exposure to chromium."
1290204,Qi et al. 2000,"Chromium(III)-induced 8-hydroxydeoxyguanosine in DNA and its reduction by antioxidants: comparative effects of melatonin, ascorbate, and vitamin E","Chromium compounds are well documented carcinogens. Cr(III) is more reactive than Cr(VI) toward DNA under in vitro conditions. In the present study, we investigated the ability of Cr(III) to induce oxidative DNA damage by examining the formation of 8-hydroxydeoxyguanosine (8-OH-dG) in calf thymus DNA incubated with CrCl(3) plus H(2)O(2). We measured 8-OH-dG using HPLC with electrochemical detection. In the presence of H(2)O(2), we observed that Cr(III)-induced formation of 8-OH-dG in isolated DNA was dose and time dependent. Melatonin, ascorbate, and vitamin E (Trolox), all of which are free radical scavengers, markedly inhibited the formation of 8-OH-dG in a concentration-dependent manner. The concentration that reduced DNA damage by 50% was 0.51, 30.4, and 36.2 microM for melatonin, ascorbate, and Trolox, respectively. The results show that melatonin is 60- and 70-fold more effective than ascorbate or vitamin E, respectively, in reducing oxidative DNA damage in this in vitro model. These findings also are consistent with the conclusion that the carcinogenic mechanism of Cr(III) is possibly due to Cr(III)-mediated Fenton-type reactions and that melatonin's highly protective effects against Cr(III) relate, at least in part, to its direct hydroxyl radical scavenging ability.","Chromium(III)-induced 8-hydroxydeoxyguanosine in DNA and its reduction by antioxidants: comparative effects of melatonin, ascorbate, and vitamin E Abs: Chromium compounds are well documented carcinogens. Cr(III) is more reactive than Cr(VI) toward DNA under in vitro conditions. In the present study, we investigated the ability of Cr(III) to induce oxidative DNA damage by examining the formation of 8-hydroxydeoxyguanosine (8-OH-dG) in calf thymus DNA incubated with CrCl(3) plus H(2)O(2). We measured 8-OH-dG using HPLC with electrochemical detection. In the presence of H(2)O(2), we observed that Cr(III)-induced formation of 8-OH-dG in isolated DNA was dose and time dependent. Melatonin, ascorbate, and vitamin E (Trolox), all of which are free radical scavengers, markedly inhibited the formation of 8-OH-dG in a concentration-dependent manner. The concentration that reduced DNA damage by 50% was 0.51, 30.4, and 36.2 microM for melatonin, ascorbate, and Trolox, respectively. The results show that melatonin is 60- and 70-fold more effective than ascorbate or vitamin E, respectively, in reducing oxidative DNA damage in this in vitro model. These findings also are consistent with the conclusion that the carcinogenic mechanism of Cr(III) is possibly due to Cr(III)-mediated Fenton-type reactions and that melatonin's highly protective effects against Cr(III) relate, at least in part, to its direct hydroxyl radical scavenging ability."
1290202,Bagchi et al. 2000,"Role of p53 tumor suppressor gene in the toxicity of TCDD, endrin, naphthalene, and chromium (VI) in liver and brain tissues of mice","It has been postulated that tumor suppressor genes are involved in the cascade of events leading to the toxicity of diverse xenobiotics. Therefore, we have assessed the comparative effects of 0.01, 0.10, and 0.50 median lethal doses (LD(50)) of 2,3,7, 8-tetrachlorodibenzo-p-dioxin (TCDD), endrin, naphthalene, and sodium dichromate (VI) [Cr(VI)] on lipid peroxidation, DNA fragmentation, and enhanced production of superoxide anion (cytochrome c reduction) in liver and brain tissues of p53-deficient and standard C57BL/6NTac mice to determine the role of p53 gene in the toxic manifestations produced by these diverse xenobiotics. In general, p53-deficient mice are more susceptible to all four xenobiotics than C57BL/6NTac mice, with dose-dependent effects being observed. Specifically, at a 0.50 LD(50) dose, naphthalene and Cr(VI) induced the greatest toxicity in the liver tissue of mice, and naphthalene and endrin exhibited the greatest effect in the brain tissue. At this dose, TCDD, endrin, naphthalene, and Cr(VI) induced 2.3- to 3.7-fold higher increases in hepatic lipid peroxidation and 1.8- to 3.0-fold higher increases in brain lipid peroxidation in p53-deficient mice than in C57BL/6NTac mice. At a 0. 10 LD(50) dose, TCDD, endrin, naphthalene, and Cr(VI) induced 1.3- to 1.8-fold higher increases in hepatic lipid peroxidation and 1.4- to 1.9-fold higher increases in brain lipid peroxidation in p53-deficient mice than in C57BL/6NTac mice. Similar results were observed with respect to DNA fragmentation and cytochrome c reduction (superoxide anion production). For example, at the 0.10 LD(50) dose, the four xenobiotics induced increases of 1.6- to 3. 0-fold and 1.5- to 2.1-fold in brain and liver DNA fragmentation, respectively, and increases of 1.5- to 2.3-fold and 1.4- to 2.5-fold in brain and liver cytochrome c reduction (superoxide anion production), respectively, in p53-deficient mice compared with control C57BL/6NTac mice. These results suggest that the p53 tumor suppressor gene may play a role in the toxicity of structurally diverse xenobiotics.","Role of p53 tumor suppressor gene in the toxicity of TCDD, endrin, naphthalene, and chromium (VI) in liver and brain tissues of mice Abs: It has been postulated that tumor suppressor genes are involved in the cascade of events leading to the toxicity of diverse xenobiotics. Therefore, we have assessed the comparative effects of 0.01, 0.10, and 0.50 median lethal doses (LD(50)) of 2,3,7, 8-tetrachlorodibenzo-p-dioxin (TCDD), endrin, naphthalene, and sodium dichromate (VI) [Cr(VI)] on lipid peroxidation, DNA fragmentation, and enhanced production of superoxide anion (cytochrome c reduction) in liver and brain tissues of p53-deficient and standard C57BL/6NTac mice to determine the role of p53 gene in the toxic manifestations produced by these diverse xenobiotics. In general, p53-deficient mice are more susceptible to all four xenobiotics than C57BL/6NTac mice, with dose-dependent effects being observed. Specifically, at a 0.50 LD(50) dose, naphthalene and Cr(VI) induced the greatest toxicity in the liver tissue of mice, and naphthalene and endrin exhibited the greatest effect in the brain tissue. At this dose, TCDD, endrin, naphthalene, and Cr(VI) induced 2.3- to 3.7-fold higher increases in hepatic lipid peroxidation and 1.8- to 3.0-fold higher increases in brain lipid peroxidation in p53-deficient mice than in C57BL/6NTac mice. At a 0. 10 LD(50) dose, TCDD, endrin, naphthalene, and Cr(VI) induced 1.3- to 1.8-fold higher increases in hepatic lipid peroxidation and 1.4- to 1.9-fold higher increases in brain lipid peroxidation in p53-deficient mice than in C57BL/6NTac mice. Similar results were observed with respect to DNA fragmentation and cytochrome c reduction (superoxide anion production). For example, at the 0.10 LD(50) dose, the four xenobiotics induced increases of 1.6- to 3. 0-fold and 1.5- to 2.1-fold in brain and liver DNA fragmentation, respectively, and increases of 1.5- to 2.3-fold and 1.4- to 2.5-fold in brain and liver cytochrome c reduction (superoxide anion production), respectively, in p53-deficient mice compared with control C57BL/6NTac mice. These results suggest that the p53 tumor suppressor gene may play a role in the toxicity of structurally diverse xenobiotics."
1290200,Arakawa et al. 2000,A comparative study of calf thymus DNA binding to Cr(III) and Cr(VI) ions. Evidence for the guanine N-7-chromium-phosphate chelate formation,"Chromium(VI) salts are well known to be mutagens and carcinogens and to easily cross the cell membranes. Because they are powerful oxidizing agents, Cr(VI) reacts with intracellular materials to reduce to trivalent form, which binds DNA. This study was designed to investigate the interaction of calf thymus DNA with Cr(VI) and Cr(III) in aqueous solution at pH 6.5-7.5, using Cr(VI)/DNA(P) molar ratios (r) of 1:20 to 2:1 and Cr(III)/DNA(P) molar ratios (r) of 1:80 to 1:2. UV-visible and Fourier transform infrared (FTIR) difference spectroscopic methods were used to determine the metal ion-binding sites, binding constants, and the effect of cation complexation on DNA secondary structure. Spectroscopic results showed no interaction of Cr(VI) with DNA at low anion concentrations (r = 1:20 to 1:1), whereas some perturbations of DNA bases and backbone phosphate were observed at very high Cr(VI) contents (r &gt; 1) with overall binding constant of K = 508 M(-1). Cr(III) chelates DNA via guanine N-7 and the nearest PO(2) group with overall binding constant of K = 3.15 x 10(3) M(-1). Evidence for cation chelate formation comes from major shiftings and intensity variations of the guanine band at 1717 and the phosphate asymmetric stretching vibration at 1222 cm(-1). At low Cr(III) concentration (r = 1:40), the number of Cr(III) ions bound to DNA were 6-7 cations/500 base pairs, and this increased to 30-35 cations/500 base pairs at high metal ion content (r = 1:4). DNA condensation occurred at high cation concentration (r = 1:10). No major alteration of DNA conformation was observed, and the biopolymer remained in the B family structure upon chromium complexation.","A comparative study of calf thymus DNA binding to Cr(III) and Cr(VI) ions. Evidence for the guanine N-7-chromium-phosphate chelate formation Abs: Chromium(VI) salts are well known to be mutagens and carcinogens and to easily cross the cell membranes. Because they are powerful oxidizing agents, Cr(VI) reacts with intracellular materials to reduce to trivalent form, which binds DNA. This study was designed to investigate the interaction of calf thymus DNA with Cr(VI) and Cr(III) in aqueous solution at pH 6.5-7.5, using Cr(VI)/DNA(P) molar ratios (r) of 1:20 to 2:1 and Cr(III)/DNA(P) molar ratios (r) of 1:80 to 1:2. UV-visible and Fourier transform infrared (FTIR) difference spectroscopic methods were used to determine the metal ion-binding sites, binding constants, and the effect of cation complexation on DNA secondary structure. Spectroscopic results showed no interaction of Cr(VI) with DNA at low anion concentrations (r = 1:20 to 1:1), whereas some perturbations of DNA bases and backbone phosphate were observed at very high Cr(VI) contents (r &gt; 1) with overall binding constant of K = 508 M(-1). Cr(III) chelates DNA via guanine N-7 and the nearest PO(2) group with overall binding constant of K = 3.15 x 10(3) M(-1). Evidence for cation chelate formation comes from major shiftings and intensity variations of the guanine band at 1717 and the phosphate asymmetric stretching vibration at 1222 cm(-1). At low Cr(III) concentration (r = 1:40), the number of Cr(III) ions bound to DNA were 6-7 cations/500 base pairs, and this increased to 30-35 cations/500 base pairs at high metal ion content (r = 1:4). DNA condensation occurred at high cation concentration (r = 1:10). No major alteration of DNA conformation was observed, and the biopolymer remained in the B family structure upon chromium complexation."
1290199,Solis-Heredia et al. 2000,Chromium increases pancreatic metallothionein in the rat,"The ability of chromium (Cr) salts to increase metallothionein (MT) levels in rat liver, kidney and pancreas, and its relationship with the presence of toxic effects are reported here. Rats were injected subcutaneously with 0, 10, 20, 30, 40, or 50 mg K2Cr2O7/kg and sacrificed 24 h later. Total Cr accumulation followed a dose-dependent pattern, levels in kidney being higher than those in liver or pancreas, suggesting different tissue bioavailabilities and accumulation patterns. Cr(IV) administration resulted in a tissue-specific MT induction: pancreas and liver showed five- and 3.5-fold MT increases, respectively; no increase was observed in the kidney. A positive correlation was observed between zinc and MT concentrations in liver, and between total Cr and MT concentrations in pancreas. Serum alpha-amylase activity showed a dose-dependent increase starting from 20 mg/kg, whereas serum glucose levels increased at doses higher than 30 mg/kg. Serum aspartate aminotransferase and alanine aminotransferase activities were increased in a dose-dependent manner, from 20 and 30 mg/kg, respectively. Our results showed that treatment with Cr(VI) can induce MT synthesis in pancreas and suggests a subsequent binding of Cr to MT. Also, pancreas is a target organ for Cr toxicity, and the usefulness of alpha-amylase activity as a sensitive biomarker of Cr toxicity in human exposed populations merits further study.","Chromium increases pancreatic metallothionein in the rat Abs: The ability of chromium (Cr) salts to increase metallothionein (MT) levels in rat liver, kidney and pancreas, and its relationship with the presence of toxic effects are reported here. Rats were injected subcutaneously with 0, 10, 20, 30, 40, or 50 mg K2Cr2O7/kg and sacrificed 24 h later. Total Cr accumulation followed a dose-dependent pattern, levels in kidney being higher than those in liver or pancreas, suggesting different tissue bioavailabilities and accumulation patterns. Cr(IV) administration resulted in a tissue-specific MT induction: pancreas and liver showed five- and 3.5-fold MT increases, respectively; no increase was observed in the kidney. A positive correlation was observed between zinc and MT concentrations in liver, and between total Cr and MT concentrations in pancreas. Serum alpha-amylase activity showed a dose-dependent increase starting from 20 mg/kg, whereas serum glucose levels increased at doses higher than 30 mg/kg. Serum aspartate aminotransferase and alanine aminotransferase activities were increased in a dose-dependent manner, from 20 and 30 mg/kg, respectively. Our results showed that treatment with Cr(VI) can induce MT synthesis in pancreas and suggests a subsequent binding of Cr to MT. Also, pancreas is a target organ for Cr toxicity, and the usefulness of alpha-amylase activity as a sensitive biomarker of Cr toxicity in human exposed populations merits further study."
1290198,Pereira et al. 1999,Individual study of chromium in the stainless steel implants degradation: an experimental study in mice,"To study the accumulation and the histological effects in mice organs caused by hexavalent chromium, one of the corrosion products released from AISI 316L stainless steel implants, mice groups were subcutaneously injected with a metallic solution of chromium during a certain period of time. Similar injections were made with HBSS (Hank's Balanced Salt Solution) in other groups to be used as controls. The levels of chromium found in the liver, kidney and spleen of the control and the treated animals were obtained by atomic absorption spectrometry (AAS) and were compared to those obtained by AdSV (adsorptive stripping voltammetry) to test the accuracy of the results. During the experimental period, the liver and spleen showed a progressive and significant accumulation of chromium whereas in the kidney the significant accumulation found after the first week practically remained unchanged during the four weeks. Apparently, the histological analysis of these tissues did not evidence any relevant morphological alteration induced by the chromium accumulations during the four weeks of treatment.","Individual study of chromium in the stainless steel implants degradation: an experimental study in mice Abs: To study the accumulation and the histological effects in mice organs caused by hexavalent chromium, one of the corrosion products released from AISI 316L stainless steel implants, mice groups were subcutaneously injected with a metallic solution of chromium during a certain period of time. Similar injections were made with HBSS (Hank's Balanced Salt Solution) in other groups to be used as controls. The levels of chromium found in the liver, kidney and spleen of the control and the treated animals were obtained by atomic absorption spectrometry (AAS) and were compared to those obtained by AdSV (adsorptive stripping voltammetry) to test the accuracy of the results. During the experimental period, the liver and spleen showed a progressive and significant accumulation of chromium whereas in the kidney the significant accumulation found after the first week practically remained unchanged during the four weeks. Apparently, the histological analysis of these tissues did not evidence any relevant morphological alteration induced by the chromium accumulations during the four weeks of treatment."
1290196,Tsou et al. 1999,Effects of mannitol or catalase on the generation of reactive oxygen species leading to DNA damage by Chromium(VI) reduction with ascorbate,"Interaction of Cr(VI) and ascorbate in vitro generates Cr(V), Cr(IV), Cr(III), carbon-based alkyl radicals, COO(*)(-), (*)OH, and ascorbate radicals and induces DNA interstrand cross-links at guanines. To determine which specific Cr species and free radicals cause DNA damage, we investigated the effects of mannitol and catalase on the formation of reactive intermediates, Cr-DNA associations, DNA polymerase-stop sites, and 8-hydroxydeoxyguanosine (8-OHdG) adducts induced by Cr(VI)/ascorbate in a Hepes buffer. EPR spectra showed that mannitol trapped reactive Cr(V), forming a stable Cr(V)-diol complex, and inhibited the radicals induced by Cr(VI)/ascorbate, whereas catalase or heat-denatured catalase enhanced the levels of Cr(V) without altering the radical signals. Mannitol markedly inhibited the retarded gel electrophoretic mobility of supercoiled plasmids and the formation of DNA polymerase-stop sites induced by Cr(VI)/ascorbate, but catalase did not. On the other hand, mannitol reduced only 32% of the Cr-DNA adducts induced by Cr(VI)/ascorbate, suggesting that Cr monoadducts (possibly DNA-Cr-mannitol adducts) are the major lesions generated in the Cr(VI)/ascorbate/mannitol/DNA solution. Native catalase but not heat-denatured catalase protected approximately 25% of the Cr-DNA adducts induced by Cr(VI)/ascorbate, suggesting that hydrogen peroxide may be involved. Mannitol could not completely inhibit the formation of 8-OHdG adducts induced by Cr(VI)/ascorbate, indicating that this DNA damage may be generated before the action of mannitol to trap Cr(V) and reactive oxygen species. Alternatively, Cr-peroxide intermediates may also lead to 8-OHdG formation to account for the incomplete prevention by mannitol. Catalase or heat-denatured catalase partially protected the formation of 8-OHdG adducts induced by Cr(VI)/ascorbate, suggesting an effect of proteins. Together, the results from this study suggest that the primary species generated during the reduction of Cr(VI) by ascorbate are hydroxyl radicals and Cr(V) species, responsible for the formation of 8-OHdG and DNA cross-links, respectively.","Effects of mannitol or catalase on the generation of reactive oxygen species leading to DNA damage by Chromium(VI) reduction with ascorbate Abs: Interaction of Cr(VI) and ascorbate in vitro generates Cr(V), Cr(IV), Cr(III), carbon-based alkyl radicals, COO(*)(-), (*)OH, and ascorbate radicals and induces DNA interstrand cross-links at guanines. To determine which specific Cr species and free radicals cause DNA damage, we investigated the effects of mannitol and catalase on the formation of reactive intermediates, Cr-DNA associations, DNA polymerase-stop sites, and 8-hydroxydeoxyguanosine (8-OHdG) adducts induced by Cr(VI)/ascorbate in a Hepes buffer. EPR spectra showed that mannitol trapped reactive Cr(V), forming a stable Cr(V)-diol complex, and inhibited the radicals induced by Cr(VI)/ascorbate, whereas catalase or heat-denatured catalase enhanced the levels of Cr(V) without altering the radical signals. Mannitol markedly inhibited the retarded gel electrophoretic mobility of supercoiled plasmids and the formation of DNA polymerase-stop sites induced by Cr(VI)/ascorbate, but catalase did not. On the other hand, mannitol reduced only 32% of the Cr-DNA adducts induced by Cr(VI)/ascorbate, suggesting that Cr monoadducts (possibly DNA-Cr-mannitol adducts) are the major lesions generated in the Cr(VI)/ascorbate/mannitol/DNA solution. Native catalase but not heat-denatured catalase protected approximately 25% of the Cr-DNA adducts induced by Cr(VI)/ascorbate, suggesting that hydrogen peroxide may be involved. Mannitol could not completely inhibit the formation of 8-OHdG adducts induced by Cr(VI)/ascorbate, indicating that this DNA damage may be generated before the action of mannitol to trap Cr(V) and reactive oxygen species. Alternatively, Cr-peroxide intermediates may also lead to 8-OHdG formation to account for the incomplete prevention by mannitol. Catalase or heat-denatured catalase partially protected the formation of 8-OHdG adducts induced by Cr(VI)/ascorbate, suggesting an effect of proteins. Together, the results from this study suggest that the primary species generated during the reduction of Cr(VI) by ascorbate are hydroxyl radicals and Cr(V) species, responsible for the formation of 8-OHdG and DNA cross-links, respectively."
1290195,Paustenbach and  Finley 1999,DNA-protein cross-links as a biomarker of Cr(VI) exposure,Comment on A. Zhitkovich et al. :Utilization of DNA-protein cross-links as a biomarker of chromium exposure. Environ Health Perspect 106(suppl 4):969-974 (1998).,DNA-protein cross-links as a biomarker of Cr(VI) exposure Abs: Comment on A. Zhitkovich et al. :Utilization of DNA-protein cross-links as a biomarker of chromium exposure. Environ Health Perspect 106(suppl 4):969-974 (1998).
1290194,Shumilla and  Barchowsky 1999,Inhibition of protein synthesis by chromium(VI) differentially affects expression of urokinase and its receptor in human type II pneumocytes,"Exposure to chromium(VI) increases the incidence of cancer, respiratory distress, and pulmonary fibrosis. The latter is a pathological disorder characterized by decreased urokinase-type plasminogen activator (uPA) activity and fibrinolysis. In this study, treatment of alveolar type II cells (A549) with 1 to 5 microM chromium(VI) for 4 and 12 h decreased both the specific activity and the amount of uPA protein. Chromium reduced uPA protein levels by inhibiting protein synthesis and had no effect on uPA mRNA levels or the rate of uPA protein degradation. In contrast, both mRNA and protein levels for the uPA receptor (uPAR) were increased by treatment with concentrations of chromium(VI) that did not completely inhibit protein synthesis. The chromium-induced increase in uPAR resulted from increased message stability. These data indicate that chromium has differential effects on expression of the proteins in the pulmonary fibrinolytic cascade. The net loss of uPA activity may promote fibrosis following inhalation of chromium(VI).","Inhibition of protein synthesis by chromium(VI) differentially affects expression of urokinase and its receptor in human type II pneumocytes Abs: Exposure to chromium(VI) increases the incidence of cancer, respiratory distress, and pulmonary fibrosis. The latter is a pathological disorder characterized by decreased urokinase-type plasminogen activator (uPA) activity and fibrinolysis. In this study, treatment of alveolar type II cells (A549) with 1 to 5 microM chromium(VI) for 4 and 12 h decreased both the specific activity and the amount of uPA protein. Chromium reduced uPA protein levels by inhibiting protein synthesis and had no effect on uPA mRNA levels or the rate of uPA protein degradation. In contrast, both mRNA and protein levels for the uPA receptor (uPAR) were increased by treatment with concentrations of chromium(VI) that did not completely inhibit protein synthesis. The chromium-induced increase in uPAR resulted from increased message stability. These data indicate that chromium has differential effects on expression of the proteins in the pulmonary fibrinolytic cascade. The net loss of uPA activity may promote fibrosis following inhalation of chromium(VI)."
1290193,Shi et al. 1999,"Cr(IV) causes activation of nuclear transcription factor-kappa B, DNA strand breaks and dG hydroxylation via free radical reactions","Electrophoretic mobility shift, DNA strand breakage assays and electron spin resonance (ESR) spin trapping were used to investigate the activation of nuclear transcription factor (NF)-kappa B, DNA strand breakage and 2'-deoxyguanosine hydroxylation induced by Cr(IV), as well the role of free radical reactions in these processes. Incubation of synthesized Cr(IV)-glutathione complex with cultured Jurkat cells resulted in activation of DNA binding activity of NF-kappa B. Cr(VI) is also able to induce NF-kappa B activation through Cr(V) and Cr(IV) intermediates generated during the reduction of Cr(VI) by the cells. Cr(III) did not cause observable NF-kappa B activation due to its inability to cross cell membranes. Cr(IV)-induced NF-kappa B activation is dose-dependent. Catalase inhibited the activation while superoxide dismutase enhanced it. The metal chelator, deferoxamine, and hydroxyl (.OH) radical scavengers, sodium formate and aspirin, also inhibited the NF-kappa B activation. Electrophoretic assays using lambda Hind III linear DNA showed that, in the presence of H2O2, Cr(IV) is capable of causing DNA strand breaks. Deferoxamine, sodium formate and aspirin inhibited the DNA strand breaks. HPLC measurements also show that .OH radical generated by the Cr(IV)-mediated reaction with H2O2 was capable of causing 2'-deoxyguanosine (dG) hydroxylation to generate 8-hydroxyguanosine (8-OHdG). The relative magnitude of 8-OHdG formation correlated with the generation of .OH radicals. ESR spin trapping measurements showed that reaction of Cr(IV) with H2O2 generated .OH radicals, which were inhibited by deferoxamine, sodium formate and aspirin. The results show that Cr(IV) can cause NF-kappa B activation, DNA strand breaks and dG hydroxylation through .OH radical-initiated reactions. This reactive chromium intermediate may play an important role in the mechanism of Cr(VI)-induced carcinogenesis. The results also suggest that the Cr(IV)-glutathione complex may be used as a model compound to study the role of Cr(IV) in Cr(VI) carcinogenicity.","Cr(IV) causes activation of nuclear transcription factor-kappa B, DNA strand breaks and dG hydroxylation via free radical reactions Abs: Electrophoretic mobility shift, DNA strand breakage assays and electron spin resonance (ESR) spin trapping were used to investigate the activation of nuclear transcription factor (NF)-kappa B, DNA strand breakage and 2'-deoxyguanosine hydroxylation induced by Cr(IV), as well the role of free radical reactions in these processes. Incubation of synthesized Cr(IV)-glutathione complex with cultured Jurkat cells resulted in activation of DNA binding activity of NF-kappa B. Cr(VI) is also able to induce NF-kappa B activation through Cr(V) and Cr(IV) intermediates generated during the reduction of Cr(VI) by the cells. Cr(III) did not cause observable NF-kappa B activation due to its inability to cross cell membranes. Cr(IV)-induced NF-kappa B activation is dose-dependent. Catalase inhibited the activation while superoxide dismutase enhanced it. The metal chelator, deferoxamine, and hydroxyl (.OH) radical scavengers, sodium formate and aspirin, also inhibited the NF-kappa B activation. Electrophoretic assays using lambda Hind III linear DNA showed that, in the presence of H2O2, Cr(IV) is capable of causing DNA strand breaks. Deferoxamine, sodium formate and aspirin inhibited the DNA strand breaks. HPLC measurements also show that .OH radical generated by the Cr(IV)-mediated reaction with H2O2 was capable of causing 2'-deoxyguanosine (dG) hydroxylation to generate 8-hydroxyguanosine (8-OHdG). The relative magnitude of 8-OHdG formation correlated with the generation of .OH radicals. ESR spin trapping measurements showed that reaction of Cr(IV) with H2O2 generated .OH radicals, which were inhibited by deferoxamine, sodium formate and aspirin. The results show that Cr(IV) can cause NF-kappa B activation, DNA strand breaks and dG hydroxylation through .OH radical-initiated reactions. This reactive chromium intermediate may play an important role in the mechanism of Cr(VI)-induced carcinogenesis. The results also suggest that the Cr(IV)-glutathione complex may be used as a model compound to study the role of Cr(IV) in Cr(VI) carcinogenicity."
1290189,Martin et al. 1998,"Hypervalent chromium mimics reactive oxygen species as measured by the oxidant-sensitive dyes 2',7'-dichlorofluorescin and dihydrorhodamine","Intracellular metabolism of the carcinogen chromate [Cr(VI)] produces the oxidative stress and oxidative DNA damage associated with its genotoxicity. Such oxidative stress has previously been measured by fluorescence using oxidant-sensitive dyes and attributed to the formation of reactive oxygen species (ROS). However, metabolism of Cr(VI) also produces Cr(IV) and Cr(V) which can directly damage biological macromolecules without forming ROS. We used the high-valence chromium species, bis(2-ethyl-2-hydroxybutyrato)oxochromate(V) [Cr(V)-EHBA], to test whether high-valence chromium would also react with the oxidant-sensitive dyes 2',7'-dichlorofluorescin (DCFH) and dihydrorhodamine (DHR). Cr(V)-EHBA caused both dyes to fluoresce over a wide dynamic range and under conditions which indicated that Cr(V) had reacted directly with both dyes without first forming a diffusible radical species. Dimethylthiourea (DMTU) and ethanol did not affect Cr(V)-induced fluorescence in vitro or Cr(VI)-induced fluorescence in A549 cells. Under the same conditions, ethanol and DMTU increased the extent of hydrogen peroxide-induced fluorescence. As chromium-induced fluorescence was unaffected by radical scavengers and was qualitatively different from hydrogen peroxide-induced fluorescence, we conclude that DCF and R123 fluorescence in chromate-treated A549 cells is a qualitative and cumulative measure of intracellular Cr(V) formation and not ROS.","Hypervalent chromium mimics reactive oxygen species as measured by the oxidant-sensitive dyes 2',7'-dichlorofluorescin and dihydrorhodamine Abs: Intracellular metabolism of the carcinogen chromate [Cr(VI)] produces the oxidative stress and oxidative DNA damage associated with its genotoxicity. Such oxidative stress has previously been measured by fluorescence using oxidant-sensitive dyes and attributed to the formation of reactive oxygen species (ROS). However, metabolism of Cr(VI) also produces Cr(IV) and Cr(V) which can directly damage biological macromolecules without forming ROS. We used the high-valence chromium species, bis(2-ethyl-2-hydroxybutyrato)oxochromate(V) [Cr(V)-EHBA], to test whether high-valence chromium would also react with the oxidant-sensitive dyes 2',7'-dichlorofluorescin (DCFH) and dihydrorhodamine (DHR). Cr(V)-EHBA caused both dyes to fluoresce over a wide dynamic range and under conditions which indicated that Cr(V) had reacted directly with both dyes without first forming a diffusible radical species. Dimethylthiourea (DMTU) and ethanol did not affect Cr(V)-induced fluorescence in vitro or Cr(VI)-induced fluorescence in A549 cells. Under the same conditions, ethanol and DMTU increased the extent of hydrogen peroxide-induced fluorescence. As chromium-induced fluorescence was unaffected by radical scavengers and was qualitatively different from hydrogen peroxide-induced fluorescence, we conclude that DCF and R123 fluorescence in chromate-treated A549 cells is a qualitative and cumulative measure of intracellular Cr(V) formation and not ROS."
1290188,Knasmüller et al. 1998,Detection of genotoxic effects of heavy metal contaminated soils with plant bioassays,"Aim of the present study was the development of a bioassay which enables the detection of genotoxic effects of heavy metal contaminated soils. In the first part of the present study, the data base on metal effects in plant bioassays was extended. Four metal salts, namely Cr(VI)O3, Cr(III)Cl3, Ni(II)Cl2 and Sb(III)Cl3 were tested comparatively in MN tests with pollen tetrad cells of Tradescantia clone #4430 and in meristematic root tip cells of Vicia faba. With Cr6+ and Ni2+, clear-cut dose-effects were observed in a range between 0.75 and 10.0 mM, whereas this was not the case with Cr3+ (range tested 1.25-10 mM) and Sb3+ (range 0.30-5.25 mM). In Vicia, negative results were obtained with the four metal salts under all conditions of test. To compare the mutagenic potencies of the metals, the increases of the regression curves (k-values) were calculated, they indicate the number of MN induced per mM in 100 tetrad cells. The corresponding values for Cr6+ and Ni2+ are 0.87 and 1.05, respectively. It appears that the Tradescantia system is in particular sensitive towards those metal species which cause DNA damage in animals and man such as Cr6+, Cd2+, Ni2+, and Zn2+, whereas no clear positive results were obtained with less harmful metal ions such as Cu2+, Cr3+ or Sb3+. In the second part of the study, the mutagenic effects of four metal contaminated soils and two types of standardized leachates (pH 4.0 and pH 7.0) of these soils were tested in Tradescantia and in Vicia. In addition, chemical analyses were carried out to determine the metal concentrations in the soils and in the extracts. Two of the samples contained highly elevated levels of a number of metals (Zn, Pb, Cu, Cd, Sb, As), one soil came from the Central Austrian Alps and contained high As levels only. Direct exposure of the Tradescantia plants in the soils resulted in a drastic increase of the MN frequencies over the background. The lowest effect was seen with the Slovakian soil which contained in particular Sb and As (4.5-fold increase over the background), with the other soils, the induced frequencies were 11-15-fold over the control values. On the contrary, negative results were obtained upon exposure of Tradescantia cuttings in the leachates and upon implantation of germinated Vicia beans in the soils. The results of the present study indicate that Trad-MN assays with direct exposure of intact plants is an appropriate method which enables to detect genotoxic effects of metal contaminated soils in situ. This simple and fast biomonitoring assays might be a valuable supplement to analytical analyses of contaminated soils.","Detection of genotoxic effects of heavy metal contaminated soils with plant bioassays Abs: Aim of the present study was the development of a bioassay which enables the detection of genotoxic effects of heavy metal contaminated soils. In the first part of the present study, the data base on metal effects in plant bioassays was extended. Four metal salts, namely Cr(VI)O3, Cr(III)Cl3, Ni(II)Cl2 and Sb(III)Cl3 were tested comparatively in MN tests with pollen tetrad cells of Tradescantia clone #4430 and in meristematic root tip cells of Vicia faba. With Cr6+ and Ni2+, clear-cut dose-effects were observed in a range between 0.75 and 10.0 mM, whereas this was not the case with Cr3+ (range tested 1.25-10 mM) and Sb3+ (range 0.30-5.25 mM). In Vicia, negative results were obtained with the four metal salts under all conditions of test. To compare the mutagenic potencies of the metals, the increases of the regression curves (k-values) were calculated, they indicate the number of MN induced per mM in 100 tetrad cells. The corresponding values for Cr6+ and Ni2+ are 0.87 and 1.05, respectively. It appears that the Tradescantia system is in particular sensitive towards those metal species which cause DNA damage in animals and man such as Cr6+, Cd2+, Ni2+, and Zn2+, whereas no clear positive results were obtained with less harmful metal ions such as Cu2+, Cr3+ or Sb3+. In the second part of the study, the mutagenic effects of four metal contaminated soils and two types of standardized leachates (pH 4.0 and pH 7.0) of these soils were tested in Tradescantia and in Vicia. In addition, chemical analyses were carried out to determine the metal concentrations in the soils and in the extracts. Two of the samples contained highly elevated levels of a number of metals (Zn, Pb, Cu, Cd, Sb, As), one soil came from the Central Austrian Alps and contained high As levels only. Direct exposure of the Tradescantia plants in the soils resulted in a drastic increase of the MN frequencies over the background. The lowest effect was seen with the Slovakian soil which contained in particular Sb and As (4.5-fold increase over the background), with the other soils, the induced frequencies were 11-15-fold over the control values. On the contrary, negative results were obtained upon exposure of Tradescantia cuttings in the leachates and upon implantation of germinated Vicia beans in the soils. The results of the present study indicate that Trad-MN assays with direct exposure of intact plants is an appropriate method which enables to detect genotoxic effects of metal contaminated soils in situ. This simple and fast biomonitoring assays might be a valuable supplement to analytical analyses of contaminated soils."
1290187,Singh et al. 1998,Chromium-induced genotoxicity and apoptosis: relationship to chromium carcinogenesis (review),"The adverse health effects linked with chromium (Cr) exposure, the role of solubility and chemical speciation of Cr compounds, and the diverse cellular and molecular effects of Cr make the study of Cr carcinogenesis and toxicology very interesting and complex. Certain Cr compounds are prominent metal carcinogens in both occupational and environmental settings. Inhaled particulate forms of hexavalent Cr [Cr(VI)] cause lung cancer as well as lung toxicity. Some of the important factors in determining the biological outcome of Cr exposure include the bioavailability, chemical speciation and solubility of Cr compounds, intracellular reduction, and interaction of Cr with DNA. The stable oxidation states of Cr found in nature are Cr(III) and Cr(VI). Cr(III) is unable to enter cells but Cr(VI) enters into cells through membrane anionic transporters. Intracellular Cr(VI) is metabolically reduced to the ultimate Cr(III). Cr(VI) does not react with macromolecules such as DNA, RNA, proteins and lipids. However, both Cr(III) and the reductional intermediate Cr(V) are capable of co-ordinate covalent interactions with macromolecules. At the genomic level, Cr genotoxicity manifests as gene mutations, several types of DNA lesions and inhibition of macromolecular synthesis. At the cellular level, Cr exposure may lead to cell cycle arrest, apoptosis, premature terminal growth arrest, or neoplastic transformation. Cr-induced DNA-DNA interstrand crosslinks (DDC), the tumor suppressor gene p53 and oxidative processes are some of the major factors that may play a significant role in determining the cellular outcome in response to Cr exposure. We have utilized cellular, molecular, pharmacological, and genetic approaches to understand the interrelationship between Cr-induced genotoxicity, apoptosis and carcinogenesis. This review is based on the results and inferences of this research. We hope this review will clarify existing concepts and also introduce novel perspectives in chromium carcinogenesis research.","Chromium-induced genotoxicity and apoptosis: relationship to chromium carcinogenesis (review) Abs: The adverse health effects linked with chromium (Cr) exposure, the role of solubility and chemical speciation of Cr compounds, and the diverse cellular and molecular effects of Cr make the study of Cr carcinogenesis and toxicology very interesting and complex. Certain Cr compounds are prominent metal carcinogens in both occupational and environmental settings. Inhaled particulate forms of hexavalent Cr [Cr(VI)] cause lung cancer as well as lung toxicity. Some of the important factors in determining the biological outcome of Cr exposure include the bioavailability, chemical speciation and solubility of Cr compounds, intracellular reduction, and interaction of Cr with DNA. The stable oxidation states of Cr found in nature are Cr(III) and Cr(VI). Cr(III) is unable to enter cells but Cr(VI) enters into cells through membrane anionic transporters. Intracellular Cr(VI) is metabolically reduced to the ultimate Cr(III). Cr(VI) does not react with macromolecules such as DNA, RNA, proteins and lipids. However, both Cr(III) and the reductional intermediate Cr(V) are capable of co-ordinate covalent interactions with macromolecules. At the genomic level, Cr genotoxicity manifests as gene mutations, several types of DNA lesions and inhibition of macromolecular synthesis. At the cellular level, Cr exposure may lead to cell cycle arrest, apoptosis, premature terminal growth arrest, or neoplastic transformation. Cr-induced DNA-DNA interstrand crosslinks (DDC), the tumor suppressor gene p53 and oxidative processes are some of the major factors that may play a significant role in determining the cellular outcome in response to Cr exposure. We have utilized cellular, molecular, pharmacological, and genetic approaches to understand the interrelationship between Cr-induced genotoxicity, apoptosis and carcinogenesis. This review is based on the results and inferences of this research. We hope this review will clarify existing concepts and also introduce novel perspectives in chromium carcinogenesis research."
1290186,Voitkun et al. 1998,Cr(III)-mediated crosslinks of glutathione or amino acids to the DNA phosphate backbone are mutagenic in human cells,"Carcinogenic Cr(VI) compounds were previously found to induce amino acid/glutathione-Cr(III)-DNA crosslinks with the site of adduction on the phosphate backbone. Utilizing the pSP189 shuttle vector plasmid we found that these ternary DNA adducts were mutagenic in human fibroblasts. The Cr(III)-glutathione adduct was the most potent in this assay, followed by Cr(III)-His and Cr(III)-Cys adducts. Binary Cr(III)-DNA complexes were only weakly mutagenic, inducing a significant response only at a 10 times higher number of adducts compared with Cr(III)-glutathione. Single base substitutions at the G:C base pairs were the predominant type of mutations for all Cr(III) adducts. Cr(III), Cr(III)-Cys and Cr(III)-His adducts induced G:C--&gt;A:T transitions and G:C--&gt;T:A transversions with almost equal frequency, whereas the Cr(III)-glutathione mutational spectrum was dominated by G:C--&gt;T:A transversions. Adduct-induced mutations were targeted toward G:C base pairs with either A or G in the 3' position to the mutated G, while spontaneous mutations occurred mostly at G:C base pairs with a 3' A. No correlation was found between the sites of DNA adduction and positions of base substitution, as adducts were formed randomly on DNA with no base specificity. The observed mutagenicity of Cr(III)-induced phosphotriesters demonstrates the importance of a Cr(III)-dependent pathway in Cr(VI) carcinogenicity.","Cr(III)-mediated crosslinks of glutathione or amino acids to the DNA phosphate backbone are mutagenic in human cells Abs: Carcinogenic Cr(VI) compounds were previously found to induce amino acid/glutathione-Cr(III)-DNA crosslinks with the site of adduction on the phosphate backbone. Utilizing the pSP189 shuttle vector plasmid we found that these ternary DNA adducts were mutagenic in human fibroblasts. The Cr(III)-glutathione adduct was the most potent in this assay, followed by Cr(III)-His and Cr(III)-Cys adducts. Binary Cr(III)-DNA complexes were only weakly mutagenic, inducing a significant response only at a 10 times higher number of adducts compared with Cr(III)-glutathione. Single base substitutions at the G:C base pairs were the predominant type of mutations for all Cr(III) adducts. Cr(III), Cr(III)-Cys and Cr(III)-His adducts induced G:C--&gt;A:T transitions and G:C--&gt;T:A transversions with almost equal frequency, whereas the Cr(III)-glutathione mutational spectrum was dominated by G:C--&gt;T:A transversions. Adduct-induced mutations were targeted toward G:C base pairs with either A or G in the 3' position to the mutated G, while spontaneous mutations occurred mostly at G:C base pairs with a 3' A. No correlation was found between the sites of DNA adduction and positions of base substitution, as adducts were formed randomly on DNA with no base specificity. The observed mutagenicity of Cr(III)-induced phosphotriesters demonstrates the importance of a Cr(III)-dependent pathway in Cr(VI) carcinogenicity."
1290185,Dillon et al. 1998,"Permeability, cytotoxicity, and genotoxicity of chromium (V) and chromium (VI) complexes in V79 Chinese hamster lung cells","The genotoxicity of Cr(V) complexes in mammalian cells (V79 Chinese hamster lung cells) has been studied for the first time using the in vitro micronucleus assay. Two complexes were investigated, [CrO(ehba)2]-, which undergoes ligand-exchange and disproportionation reactions in the cell growth medium, and [CrO(mampa)]-, which is chemically inert in the medium for the duration of the exposure period. Results of in vitro micronucleus assays show that both complexes are genotoxic and exhibit similar potencies to that of [Cr2O7]2-. The permeabilities of the Cr(V) complexes were also investigated for the first time using particle-induced X-ray emission (PIXE) analysis of individual cells. The Cr uptake increased in the order: [Cr(phen)2-(H2O)2]3+ &lt; [CrO(ehba)2]- &lt; [CrO(mampa)]- &lt; [Cr2O7]2-. Clonal assays showed that Cr(VI) exhibits an expectedly higher cytotoxicity than the Cr(V) complexes. While the genotoxicities of the Cr(V) and Cr(VI) complexes increase according to their permeabilities, the genotoxicities of the Cr(V) complexes are equal to, if not greater than, that of Cr(VI) in terms of the amount of Cr entering the cell. This supports other evidence that Cr(V), produced as a metabolic intermediate from the intracellular reduction of Cr(VI), may be important in Cr-induced cancers.","Permeability, cytotoxicity, and genotoxicity of chromium (V) and chromium (VI) complexes in V79 Chinese hamster lung cells Abs: The genotoxicity of Cr(V) complexes in mammalian cells (V79 Chinese hamster lung cells) has been studied for the first time using the in vitro micronucleus assay. Two complexes were investigated, [CrO(ehba)2]-, which undergoes ligand-exchange and disproportionation reactions in the cell growth medium, and [CrO(mampa)]-, which is chemically inert in the medium for the duration of the exposure period. Results of in vitro micronucleus assays show that both complexes are genotoxic and exhibit similar potencies to that of [Cr2O7]2-. The permeabilities of the Cr(V) complexes were also investigated for the first time using particle-induced X-ray emission (PIXE) analysis of individual cells. The Cr uptake increased in the order: [Cr(phen)2-(H2O)2]3+ &lt; [CrO(ehba)2]- &lt; [CrO(mampa)]- &lt; [Cr2O7]2-. Clonal assays showed that Cr(VI) exhibits an expectedly higher cytotoxicity than the Cr(V) complexes. While the genotoxicities of the Cr(V) and Cr(VI) complexes increase according to their permeabilities, the genotoxicities of the Cr(V) complexes are equal to, if not greater than, that of Cr(VI) in terms of the amount of Cr entering the cell. This supports other evidence that Cr(V), produced as a metabolic intermediate from the intracellular reduction of Cr(VI), may be important in Cr-induced cancers."
1290184,Tsou et al. 1997,Mutational spectrum induced by chromium(III) in shuttle vectors replicated in human cells: relationship to Cr(III)-DNA interactions,"Trivalent chromium (Cr(III)), the ultimate species of chromium (VI) intracellular reduction, can associate with DNA forming Cr(III) monoadducts and DNA-DNA cross-links. However, the mutational specificity of Cr(III) has not been determined partly because Cr(III) has difficulty entering cells. In this study, we have characterized the types of Cr(III)-induced DNA lesions in two buffer systems and the mutational spectrum of Cr(III)-treated shuttle vectors replicated in human 293 cells. Plasmids were treated with Cr(III) in buffers consisting of either 10 mM potassium phosphate, pH 7.5 (designated as KP), or 0.2 mM Tris-HCl and 20 microM EDTA, pH 7.4 (designated as TE/50). The amounts of Cr(III) bound to DNA increased as Cr(III) concentration increased in both buffers; these Cr(III)-DNA associations were stable in both buffers during a 24-h dialysis. The electrophoretic mobility of supercoiled DNA was markedly retarded in samples treated with Cr(III) in TE/50 but not KP buffer, suggesting that Cr(III)-mediated DNA-DNA cross-links were generated in TE/50 but did not form in KP. Polymerase-stop assay showed that DNA polymerases were mostly blocked at the 3' adjacent bases of guanines on templates treated with Cr(III) in TE/50 but were not observed on those treated in KP. The signals of Cr(III)-mediated cross-links generated in TE/50 buffers were reduced when they were dialyzed against KP buffers. Similarly, Cr(III)-DNA monoadducts formed in KP were converted to primer-template cross-links by dialysis against TE/50. The mutation frequency of Cr(III) in the supF gene of pSP189 or pZ189 shuttle vectors replicated in human cells increased as Cr(III) concentration increased in both buffers. DNA sequencing analysis showed that single-base substitutions (61-68%), two-base substitutions (3-5%), and deletions (21-34%) were induced in similar frequencies in plasmids treated with Cr(III) in either TE/ 50 or KP. The Cr(III)-induced base-substitution hot spots are different from those occurring spontaneously. Cr(III) enhances G.C base substitutions, particularly G.C--&gt;C.G transversions, at 5'GA, 5'CG, and 5'AG sites. Base-substitution hot spots did not correlate with strong polymerase-stop sites, suggesting that base substitutions are derived from Cr(III) monoadducts, not from DNA-DNA cross-links.","Mutational spectrum induced by chromium(III) in shuttle vectors replicated in human cells: relationship to Cr(III)-DNA interactions Abs: Trivalent chromium (Cr(III)), the ultimate species of chromium (VI) intracellular reduction, can associate with DNA forming Cr(III) monoadducts and DNA-DNA cross-links. However, the mutational specificity of Cr(III) has not been determined partly because Cr(III) has difficulty entering cells. In this study, we have characterized the types of Cr(III)-induced DNA lesions in two buffer systems and the mutational spectrum of Cr(III)-treated shuttle vectors replicated in human 293 cells. Plasmids were treated with Cr(III) in buffers consisting of either 10 mM potassium phosphate, pH 7.5 (designated as KP), or 0.2 mM Tris-HCl and 20 microM EDTA, pH 7.4 (designated as TE/50). The amounts of Cr(III) bound to DNA increased as Cr(III) concentration increased in both buffers; these Cr(III)-DNA associations were stable in both buffers during a 24-h dialysis. The electrophoretic mobility of supercoiled DNA was markedly retarded in samples treated with Cr(III) in TE/50 but not KP buffer, suggesting that Cr(III)-mediated DNA-DNA cross-links were generated in TE/50 but did not form in KP. Polymerase-stop assay showed that DNA polymerases were mostly blocked at the 3' adjacent bases of guanines on templates treated with Cr(III) in TE/50 but were not observed on those treated in KP. The signals of Cr(III)-mediated cross-links generated in TE/50 buffers were reduced when they were dialyzed against KP buffers. Similarly, Cr(III)-DNA monoadducts formed in KP were converted to primer-template cross-links by dialysis against TE/50. The mutation frequency of Cr(III) in the supF gene of pSP189 or pZ189 shuttle vectors replicated in human cells increased as Cr(III) concentration increased in both buffers. DNA sequencing analysis showed that single-base substitutions (61-68%), two-base substitutions (3-5%), and deletions (21-34%) were induced in similar frequencies in plasmids treated with Cr(III) in either TE/ 50 or KP. The Cr(III)-induced base-substitution hot spots are different from those occurring spontaneously. Cr(III) enhances G.C base substitutions, particularly G.C--&gt;C.G transversions, at 5'GA, 5'CG, and 5'AG sites. Base-substitution hot spots did not correlate with strong polymerase-stop sites, suggesting that base substitutions are derived from Cr(III) monoadducts, not from DNA-DNA cross-links."
1290183,Dillon et al. 1997,Microprobe X-ray absorption spectroscopic determination of the oxidation state of intracellular chromium following exposure of V79 Chinese hamster lung cells to genotoxic chromium complexes,The oxidation state of intracellular chromium has been determined directly in mammalian lung cells exposed to mutagenic and carcinogenic chromium compounds. Microprobe X-ray absorption spectroscopy (XAS) experiments on single V79 Chinese hamster lung cells showed that Cr(VI) and Cr(V) complexes were reduced completely (&gt;90%) to Cr(III) within 4 h of exposure of the cells. This result provides direct evidence for the hypothesis that these genotoxic oxidants react rapidly with intracellular reductants.,Microprobe X-ray absorption spectroscopic determination of the oxidation state of intracellular chromium following exposure of V79 Chinese hamster lung cells to genotoxic chromium complexes Abs: The oxidation state of intracellular chromium has been determined directly in mammalian lung cells exposed to mutagenic and carcinogenic chromium compounds. Microprobe X-ray absorption spectroscopy (XAS) experiments on single V79 Chinese hamster lung cells showed that Cr(VI) and Cr(V) complexes were reduced completely (&gt;90%) to Cr(III) within 4 h of exposure of the cells. This result provides direct evidence for the hypothesis that these genotoxic oxidants react rapidly with intracellular reductants.
1290181,Liu et al. 1996,Low frequency electron paramagnetic resonance investigation on metabolism of chromium (VI) by whole live mice,"Detection of Cr(V) in the reduction of Cr(VI) by whole live mice and its characterization were carried out by low frequency electron paramagnetic resonance (EPR). Intravenous injection of Cr(VI) to mice generated Cr(V). The Cr(V) was found predominantly in the liver with a small amount in the blood. Liver homogenates from Cr(VI) treated mice generated essentially the same Cr(V) spectrum as that obtained from the whole live mice. This Cr(V) species was identified to be a Cr(V)-nicotinamide adenine dinucleotide (NAD) (P)H complex with an oxygen bond to Cr(V). Pretreatment of the mice with ascorbic acid and glutathione reduced the Cr(V) formation, while pretreatment with reduced nicotinamide adenine dinucleotide (NADH) enhanced it. Metal chelators, ethylenediaminetetraacetic acid (EDTA), 1,10-phenanthroline, and diethylenetriaminepentaacetic acid (DTPA) inhibited the intensity of the Cr(V) signal. The results suggest that Cr(V) generated in the whole body of a live animal is a Cr(V)-NAD(P)H complex and NAD(P)H/flavoenzymes and not glutathione or ascorbate as the major one-electron Cr(VI) reductant responsible for observed formation of Cr(V)-NAD(P)H complex in vivo.","Low frequency electron paramagnetic resonance investigation on metabolism of chromium (VI) by whole live mice Abs: Detection of Cr(V) in the reduction of Cr(VI) by whole live mice and its characterization were carried out by low frequency electron paramagnetic resonance (EPR). Intravenous injection of Cr(VI) to mice generated Cr(V). The Cr(V) was found predominantly in the liver with a small amount in the blood. Liver homogenates from Cr(VI) treated mice generated essentially the same Cr(V) spectrum as that obtained from the whole live mice. This Cr(V) species was identified to be a Cr(V)-nicotinamide adenine dinucleotide (NAD) (P)H complex with an oxygen bond to Cr(V). Pretreatment of the mice with ascorbic acid and glutathione reduced the Cr(V) formation, while pretreatment with reduced nicotinamide adenine dinucleotide (NADH) enhanced it. Metal chelators, ethylenediaminetetraacetic acid (EDTA), 1,10-phenanthroline, and diethylenetriaminepentaacetic acid (DTPA) inhibited the intensity of the Cr(V) signal. The results suggest that Cr(V) generated in the whole body of a live animal is a Cr(V)-NAD(P)H complex and NAD(P)H/flavoenzymes and not glutathione or ascorbate as the major one-electron Cr(VI) reductant responsible for observed formation of Cr(V)-NAD(P)H complex in vivo."
1290180,Luo et al. 1996,"Role of chromium(IV) in the chromium(VI)-related free radical formation, dG hydroxylation, and DNA damage","A reactive Cr(IV) ester was synthesized from a reaction of CrO3 with 2,4-dimethyl-2,4-pentanediol as verified by electron spin resonance (ESR) and magnetic susceptibility measurements. ESR spin trapping studies demonstrate that the Cr(IV) ester is capable of generating hydroxyl free radical (.OH) through a Fenton-like mechanism (Cr(IV)+H2O2-->Cr(V)+.OH+OH-) with a concomitant generation of Cr(V) species (g = 1.9787). Cr(IV) caused DNA strand breaks as measured by electrophoretic assays. H2O2 enhanced the DNA strand breaks via .OH formation by a Cr(IV)-mediated Fenton-like reaction. In the Cr(IV)/H2O2 system, formate did not block Cr(V) formation, but prevented DNA damage, indicating that .OH radicals, and not Cr(V), caused the DNA damage. Reaction of Cr(VI) with ascorbate was also used as a source of Cr(IV). Incubation of Cr(VI), ascorbate, and DNA caused DNA strand breaks. A free radical trap, 5,5-dimethyl-1-pyrroline (DMPO), only slightly inhibited the DNA damage. Addition of Mn(II), which inhibited Cr(IV), caused significant protection. H2O2 enhanced the DNA damage via Cr(IV)-mediated .OH radical generation and Mn(II) inhibited the damage, again showing that Cr(IV) and its related .OH generation caused DNA strand breaks. HPLC measurements showed that .OH radicals generated by a Cr(IV)-mediated Fenton-like reaction generated 8-hydroxy-2'-deoxyguanosine from 2'-deoxyguanosine. The results demonstrate that Cr(IV) and its generated .OH radicals are capable of damaging DNA. Moreover, in comparison with Cr(V), Cr(IV) is a more potent DNA damaging agent.","Role of chromium(IV) in the chromium(VI)-related free radical formation, dG hydroxylation, and DNA damage Abs: A reactive Cr(IV) ester was synthesized from a reaction of CrO3 with 2,4-dimethyl-2,4-pentanediol as verified by electron spin resonance (ESR) and magnetic susceptibility measurements. ESR spin trapping studies demonstrate that the Cr(IV) ester is capable of generating hydroxyl free radical (.OH) through a Fenton-like mechanism (Cr(IV)+H2O2-->Cr(V)+.OH+OH-) with a concomitant generation of Cr(V) species (g = 1.9787). Cr(IV) caused DNA strand breaks as measured by electrophoretic assays. H2O2 enhanced the DNA strand breaks via .OH formation by a Cr(IV)-mediated Fenton-like reaction. In the Cr(IV)/H2O2 system, formate did not block Cr(V) formation, but prevented DNA damage, indicating that .OH radicals, and not Cr(V), caused the DNA damage. Reaction of Cr(VI) with ascorbate was also used as a source of Cr(IV). Incubation of Cr(VI), ascorbate, and DNA caused DNA strand breaks. A free radical trap, 5,5-dimethyl-1-pyrroline (DMPO), only slightly inhibited the DNA damage. Addition of Mn(II), which inhibited Cr(IV), caused significant protection. H2O2 enhanced the DNA damage via Cr(IV)-mediated .OH radical generation and Mn(II) inhibited the damage, again showing that Cr(IV) and its related .OH generation caused DNA strand breaks. HPLC measurements showed that .OH radicals generated by a Cr(IV)-mediated Fenton-like reaction generated 8-hydroxy-2'-deoxyguanosine from 2'-deoxyguanosine. The results demonstrate that Cr(IV) and its generated .OH radicals are capable of damaging DNA. Moreover, in comparison with Cr(V), Cr(IV) is a more potent DNA damaging agent."
1290179,McKay et al. 1996,Interactions of orthopaedic metals with an immortalized rat osteoblast cell line,"The toxicity of nickel, chromium (III) and (VI), vanadium and aluminium was compared in an immortalized neonatal rat osteoblast cell line using the MTT assay and a novel index of cytotoxicity, alkaline phosphatase (ALP) activity. Where toxicity was observed, ALP was a consistently more sensitive detection method than the MTT assay. The toxicity of the metals increased in the order aluminium < chromium (III) < vanadium < nickel < chromium (VI). alpha-Tocopherol partially prevented nickel-induced toxicity (as assessed by ALP activity), whereas ascorbic acid had no protective effect. Chromium (VI) was more toxic than (III), with significant toxicity observed at 0.5 microM. It is thought that Cr (III) cannot readily penetrate the cell membrane and this may account for the lower toxicity. Aluminium had a stimulatory effect on cell growth at low concentrations (0.5 microM). The combination of immortalized rat osteoblasts and the ALP activity test provides a powerful tool for in vitro testing of orthopaedic materials.","Interactions of orthopaedic metals with an immortalized rat osteoblast cell line Abs: The toxicity of nickel, chromium (III) and (VI), vanadium and aluminium was compared in an immortalized neonatal rat osteoblast cell line using the MTT assay and a novel index of cytotoxicity, alkaline phosphatase (ALP) activity. Where toxicity was observed, ALP was a consistently more sensitive detection method than the MTT assay. The toxicity of the metals increased in the order aluminium < chromium (III) < vanadium < nickel < chromium (VI). alpha-Tocopherol partially prevented nickel-induced toxicity (as assessed by ALP activity), whereas ascorbic acid had no protective effect. Chromium (VI) was more toxic than (III), with significant toxicity observed at 0.5 microM. It is thought that Cr (III) cannot readily penetrate the cell membrane and this may account for the lower toxicity. Aluminium had a stimulatory effect on cell growth at low concentrations (0.5 microM). The combination of immortalized rat osteoblasts and the ALP activity test provides a powerful tool for in vitro testing of orthopaedic materials."
1290178,Little et al. 1996,Chromium- and nickel-induced cytotoxicity in normal and transformed human keratinocytes: an investigation of pharmacological approaches to the prevention of Cr(VI)-induced cytotoxicity,"Chromium and nickel compounds cause irritancy but can also induce allergic contact dermatitis. The aims of this study were to characterize the direct cytotoxic effects of Cr(VI), Cr(III) and Ni(II) salts on keratinocytes, and to investigate pharmacological strategies to protect cells against Cr(VI)-induced cytotoxicity. Normal human keratinocytes and the HaCaT keratinocyte cell line were used. Cell viability was assessed by neutral red dye uptake, the 3-[4,5-dimethylthiazol-2-yl]-2,5-diphenyltetrazolium bromide (MTT) eluted stain assay and measurement of lactate dehydrogenase (LDH) activity in the medium. The assays varied slightly in their sensitivities (neutral red &gt; MTT &gt; LDH) although all three gave similar results. In both cell types, the relative order of cytotoxicity of the salts was Cr(VI) &gt; Ni(II) &gt; Cr(III). There were no major differences between chromium salts of a common valency. Normal human keratinocytes showed a much greater variability in their response to Cr(VI) and Ni(II) salts than HaCaT cells and were generally more resistant to Cr(VI)- and Ni(II)-induced cytotoxicity. Several drugs were screened for their potential to protect both cell types against the cytotoxic effects of Cr(VI), specifically the reducing agents ascorbic acid, cysteine and glutathione, and the Cr(VI) cellular uptake inhibitors 4,4'-diisothiocyanato-2,2'-stilbenedisulphonic acid (DIDS) and 4-acetamido-4'-isothiocyanato-2,2'-stilbenedisulphonic acid (SITS). All five drugs provided concentration-dependent protection against Cr(VI)-induced cytotoxicity but only ascorbic acid offered complete protection. Several of these pharmacological approaches to the prevention of Cr(VI) cytotoxicity confirm previous clinical studies on the inactivation of Cr(VI), while the clinical potential of others has yet to be investigated.","Chromium- and nickel-induced cytotoxicity in normal and transformed human keratinocytes: an investigation of pharmacological approaches to the prevention of Cr(VI)-induced cytotoxicity Abs: Chromium and nickel compounds cause irritancy but can also induce allergic contact dermatitis. The aims of this study were to characterize the direct cytotoxic effects of Cr(VI), Cr(III) and Ni(II) salts on keratinocytes, and to investigate pharmacological strategies to protect cells against Cr(VI)-induced cytotoxicity. Normal human keratinocytes and the HaCaT keratinocyte cell line were used. Cell viability was assessed by neutral red dye uptake, the 3-[4,5-dimethylthiazol-2-yl]-2,5-diphenyltetrazolium bromide (MTT) eluted stain assay and measurement of lactate dehydrogenase (LDH) activity in the medium. The assays varied slightly in their sensitivities (neutral red &gt; MTT &gt; LDH) although all three gave similar results. In both cell types, the relative order of cytotoxicity of the salts was Cr(VI) &gt; Ni(II) &gt; Cr(III). There were no major differences between chromium salts of a common valency. Normal human keratinocytes showed a much greater variability in their response to Cr(VI) and Ni(II) salts than HaCaT cells and were generally more resistant to Cr(VI)- and Ni(II)-induced cytotoxicity. Several drugs were screened for their potential to protect both cell types against the cytotoxic effects of Cr(VI), specifically the reducing agents ascorbic acid, cysteine and glutathione, and the Cr(VI) cellular uptake inhibitors 4,4'-diisothiocyanato-2,2'-stilbenedisulphonic acid (DIDS) and 4-acetamido-4'-isothiocyanato-2,2'-stilbenedisulphonic acid (SITS). All five drugs provided concentration-dependent protection against Cr(VI)-induced cytotoxicity but only ascorbic acid offered complete protection. Several of these pharmacological approaches to the prevention of Cr(VI) cytotoxicity confirm previous clinical studies on the inactivation of Cr(VI), while the clinical potential of others has yet to be investigated."
1290177,Tsou et al. 1996,Induction of 8-hydroxydeoxyguanosine in DNA by chromium(III) plus hydrogen peroxide and its prevention by scavengers,"The capability of Cr(III) to induce DNA lesions generated by oxidative damage was investigated in this study by examining the formation of 8-hydroxydeoxyguanosine (8-OHdG) in calf thymus DNA by CrCl3 and/or H2O2 in 10 mM phosphate buffer. In the presence of 0.5 mM H2O2, the formation of 8-OHdG markedly increased with increasing CrCl3 concentration. In contrast, H2O2 or CrCl3 alone did not cause any increase in 8-OHdG level above background. The amount of 8-OHdG induced by CrCl3 plus H2O2 was time dependent; its generation increased linearly over an incubation period of 90 min. The formation of 8-OHdG was unfavorable in an acidic solution (pH &lt; 6); the highest level of 8-OHdG was observed at pH 7-8. Scavengers of reactive oxygen species markedly inhibited the formation of 8-OHdG by CrCl3 plus H2O2; the inhibition effect was sodium azide &gt; D-mannitol &gt; Tris-HCl at an equal concentration. The induction of 8-OHdG by CrCl3 plus H2O2 remained unchanged in D2O. Moreover, an addition of catalase (2.2 U/ml) to the reaction mixture completely inhibited the formation of 8-OHdG by CrCl3/H2O2, whereas only 22% of that formation was inhibited by superoxide dismutase (11 U/ml). A large amount of bovine serum albumin (1.1 mg/ml) could reduce the formation of 8-OHdG by CrCl3 plus H2O2, thereby implying that Cr(III)-mediated DNA-protein crosslinks are unfavorable for 8-OHdG formation. Furthermore, ascorbate could prevent the formation of 8-OHdG by CrCl3 plus H2O2; the extent of prevention increased with increasing ascorbate concentration (10 microM-3 mM). Thus, ascorbate acts as a free radical scavenger in the CrCl3/H2O2 system. The above findings suggest that Cr(III)/H2O2 could generate oxidative damage to DNA, possibly through a Fenton-like reaction, i.e. Cr(III)+H2O2--&gt;Cr(IV)+.OH+OH-. This study also indicates that Cr(III), previously considered as the ultimate kinetically stable species of Cr(VI) metabolites, is capable of inducing carcinogenic lesions through interaction with a cellular oxygen species.","Induction of 8-hydroxydeoxyguanosine in DNA by chromium(III) plus hydrogen peroxide and its prevention by scavengers Abs: The capability of Cr(III) to induce DNA lesions generated by oxidative damage was investigated in this study by examining the formation of 8-hydroxydeoxyguanosine (8-OHdG) in calf thymus DNA by CrCl3 and/or H2O2 in 10 mM phosphate buffer. In the presence of 0.5 mM H2O2, the formation of 8-OHdG markedly increased with increasing CrCl3 concentration. In contrast, H2O2 or CrCl3 alone did not cause any increase in 8-OHdG level above background. The amount of 8-OHdG induced by CrCl3 plus H2O2 was time dependent; its generation increased linearly over an incubation period of 90 min. The formation of 8-OHdG was unfavorable in an acidic solution (pH &lt; 6); the highest level of 8-OHdG was observed at pH 7-8. Scavengers of reactive oxygen species markedly inhibited the formation of 8-OHdG by CrCl3 plus H2O2; the inhibition effect was sodium azide &gt; D-mannitol &gt; Tris-HCl at an equal concentration. The induction of 8-OHdG by CrCl3 plus H2O2 remained unchanged in D2O. Moreover, an addition of catalase (2.2 U/ml) to the reaction mixture completely inhibited the formation of 8-OHdG by CrCl3/H2O2, whereas only 22% of that formation was inhibited by superoxide dismutase (11 U/ml). A large amount of bovine serum albumin (1.1 mg/ml) could reduce the formation of 8-OHdG by CrCl3 plus H2O2, thereby implying that Cr(III)-mediated DNA-protein crosslinks are unfavorable for 8-OHdG formation. Furthermore, ascorbate could prevent the formation of 8-OHdG by CrCl3 plus H2O2; the extent of prevention increased with increasing ascorbate concentration (10 microM-3 mM). Thus, ascorbate acts as a free radical scavenger in the CrCl3/H2O2 system. The above findings suggest that Cr(III)/H2O2 could generate oxidative damage to DNA, possibly through a Fenton-like reaction, i.e. Cr(III)+H2O2--&gt;Cr(IV)+.OH+OH-. This study also indicates that Cr(III), previously considered as the ultimate kinetically stable species of Cr(VI) metabolites, is capable of inducing carcinogenic lesions through interaction with a cellular oxygen species."
1290176,Vainio and  Wilbourn 1993,Cancer etiology: Agents causally associated with human cancer,"Cancer is a multifactorial and multistage process, the exact mechanisms of which are still only partially known. However, even in the absence of a complete understanding of the process of carcinogenesis, we have been able to identify several factors which modify the risk of tumour development in humans. These include both endogenous and environmental factors, ranging from exposure to a single identified chemical to the occupations we follow in order to make our living. Cancer prevention strategies may differ in different parts of the world. In Europe, lung cancer is responsible for about one fourth of all cancer deaths and most of it could be prevented by eliminating tobacco smoking. Other exposures that can be controlled include occupational exposures to agents known to cause cancer at sites such as lung, bladder, paranasal sinuses, leukaemia, lymphoma and liver, as well as exposure to sunlight, known to be associated with both non-melanocytic and melanocytic skin cancer. Liver cancer is a common cancer in other regions of the world where hepatitis B virus (HBV) infection is endemic; in these areas, fungal contamination of food is also common. While immunization against HBV may be the method of choice in the long run, reduction of exposure to aflatoxins might be a more useful intermediate goal in primary prevention because of the strong interaction between hepatitis B and aflatoxin exposure on liver cancer risk. To date, few chemical agents have been proved to be of etiological relevance to cancer in humans at sites such as the breast (with the exception of oestrogenic hormones), ovary, colon-rectum and prostate.(ABSTRACT TRUNCATED AT 250 WORDS)","Cancer etiology: Agents causally associated with human cancer Abs: Cancer is a multifactorial and multistage process, the exact mechanisms of which are still only partially known. However, even in the absence of a complete understanding of the process of carcinogenesis, we have been able to identify several factors which modify the risk of tumour development in humans. These include both endogenous and environmental factors, ranging from exposure to a single identified chemical to the occupations we follow in order to make our living. Cancer prevention strategies may differ in different parts of the world. In Europe, lung cancer is responsible for about one fourth of all cancer deaths and most of it could be prevented by eliminating tobacco smoking. Other exposures that can be controlled include occupational exposures to agents known to cause cancer at sites such as lung, bladder, paranasal sinuses, leukaemia, lymphoma and liver, as well as exposure to sunlight, known to be associated with both non-melanocytic and melanocytic skin cancer. Liver cancer is a common cancer in other regions of the world where hepatitis B virus (HBV) infection is endemic; in these areas, fungal contamination of food is also common. While immunization against HBV may be the method of choice in the long run, reduction of exposure to aflatoxins might be a more useful intermediate goal in primary prevention because of the strong interaction between hepatitis B and aflatoxin exposure on liver cancer risk. To date, few chemical agents have been proved to be of etiological relevance to cancer in humans at sites such as the breast (with the exception of oestrogenic hormones), ovary, colon-rectum and prostate.(ABSTRACT TRUNCATED AT 250 WORDS)"
1290174,Nasu et al. 1993,Inhibitory effects of hexavalent chromium ions on the contraction in ileal longitudinal smooth muscle of guinea-pig,"1. The high-K (60 mM)-induced ileal tonic tensions were not affected after 5 min with (0.01-1 mM) Cr6+. However, they were inhibited dose-dependently by Cr6+ after 30 min application. 2. Cr6+ inhibited the tonic response to K more strongly than the phasic response. 3. Cr6+ did not displace Ca(2+)-concentration-response curves to the right, although it reduced the Ca2+ response size. 4. The low affinity binding sites of Ca2+ and the tissue ATP concentration during K contraction was not entirely inhibited after 5 min with 0.5 mM Cr6+. However, they were fairly inhibited after 30 min with the Cr6+. 5. We suggest that Cr6+ probably reduced tension by the interference of Ca2+ influx at the cell membrane resulting from the inhibitory action on mitochondria.","Inhibitory effects of hexavalent chromium ions on the contraction in ileal longitudinal smooth muscle of guinea-pig Abs: 1. The high-K (60 mM)-induced ileal tonic tensions were not affected after 5 min with (0.01-1 mM) Cr6+. However, they were inhibited dose-dependently by Cr6+ after 30 min application. 2. Cr6+ inhibited the tonic response to K more strongly than the phasic response. 3. Cr6+ did not displace Ca(2+)-concentration-response curves to the right, although it reduced the Ca2+ response size. 4. The low affinity binding sites of Ca2+ and the tissue ATP concentration during K contraction was not entirely inhibited after 5 min with 0.5 mM Cr6+. However, they were fairly inhibited after 30 min with the Cr6+. 5. We suggest that Cr6+ probably reduced tension by the interference of Ca2+ influx at the cell membrane resulting from the inhibitory action on mitochondria."
1290173,Moghaddas et al. 1995,Mechanisms of formation and decomposition of hypervalent chromium metabolites in the glutathione-chromium (VI) reaction,"A long-lived chromium(IV) intermediate is generated during the reaction between Cr(VI) and glutathione in glycine below pH 3. The intermediate reacts with the tripeptide to produce Cr(III) and oxidized glutathione. A dynamic magnetic susceptibility measurement based on a nuclear magnetic resonance method yielded a 2.8 microB magnetic movement for the chromium(IV) species. The intermediate is formed by parallel third-order and second-order processes. The third-order process (k = 5.9 x 10(2) M-2 s-1) involves first-order participation by each of the oxidant, reductant, and hydrogen ions. A hydrogen ion independent pathway leads to a sluggish second-order process (k = 0.11 M-1 s-1) that is first order with respect to reduced glutathione [GSH] and [Cr(VI)]. Chromium(IV) species is reduced to Cr(III) by a second-order process (k = 0.13 M-1 s-1) that is first order in each of [Cr(IV)] and [GSH] and does not depend on [H+]. At pH 3.4, a chromium(V) species was detected as a minor intermediate as well. In the pH range 6.5-7.5, three dominant chromium(V) intermediates were detected. The existence of Cr(IV) in low pH offers an opportunity to examine the mechanism of DNA damage by this rare oxidation state.","Mechanisms of formation and decomposition of hypervalent chromium metabolites in the glutathione-chromium (VI) reaction Abs: A long-lived chromium(IV) intermediate is generated during the reaction between Cr(VI) and glutathione in glycine below pH 3. The intermediate reacts with the tripeptide to produce Cr(III) and oxidized glutathione. A dynamic magnetic susceptibility measurement based on a nuclear magnetic resonance method yielded a 2.8 microB magnetic movement for the chromium(IV) species. The intermediate is formed by parallel third-order and second-order processes. The third-order process (k = 5.9 x 10(2) M-2 s-1) involves first-order participation by each of the oxidant, reductant, and hydrogen ions. A hydrogen ion independent pathway leads to a sluggish second-order process (k = 0.11 M-1 s-1) that is first order with respect to reduced glutathione [GSH] and [Cr(VI)]. Chromium(IV) species is reduced to Cr(III) by a second-order process (k = 0.13 M-1 s-1) that is first order in each of [Cr(IV)] and [GSH] and does not depend on [H+]. At pH 3.4, a chromium(V) species was detected as a minor intermediate as well. In the pH range 6.5-7.5, three dominant chromium(V) intermediates were detected. The existence of Cr(IV) in low pH offers an opportunity to examine the mechanism of DNA damage by this rare oxidation state."
1290172,Snow 1994,Effects of chromium on DNA replication in vitro,"Chromium is an environmentally significant human carcinogen with complicated metabolism and an unknown mechanism of mutagenesis. Chromium(VI) is taken up by cells as the chromate anion and is reduced intracellularly via reactive intermediates to stable Cr(III) species. Chromium(III) forms tight complexes with biological ligands, such as DNA and proteins, which are slow to exchange. In vitro, CrCl3.6H2O primarily interacts with DNA to form outer shell charge complexes with the DNA phosphates. However, at micromolar concentrations, the Cr(III) binds to a low number of saturable tight binding sites on single-stranded M13 DNA. Additional chromium interacts in a nonspecific manner with the DNA and can form intermolecular DNA cross-links. Although high concentrations of Cr(III) inhibit DNA replication, micromolar concentrations of Cr(III) can substitute for Mg2+, weakly activate the Klenow fragment of E. coli DNA polymerase I (Pol I-KF), and act as an enhancer of nucleotide incorporation. Alterations in enzyme kinetics induced by Cr(III) increase DNA polymerase processivity and the rate of polymerase bypass of DNA lesions. This results in an increased rate of spontaneous mutagenesis during DNA replication both in vitro and in vivo. Our results indicate that chromium(III) may contribute to chromate-induced mutagenesis and may be a factor in the initiation of chromium carcinogenesis.","Effects of chromium on DNA replication in vitro Abs: Chromium is an environmentally significant human carcinogen with complicated metabolism and an unknown mechanism of mutagenesis. Chromium(VI) is taken up by cells as the chromate anion and is reduced intracellularly via reactive intermediates to stable Cr(III) species. Chromium(III) forms tight complexes with biological ligands, such as DNA and proteins, which are slow to exchange. In vitro, CrCl3.6H2O primarily interacts with DNA to form outer shell charge complexes with the DNA phosphates. However, at micromolar concentrations, the Cr(III) binds to a low number of saturable tight binding sites on single-stranded M13 DNA. Additional chromium interacts in a nonspecific manner with the DNA and can form intermolecular DNA cross-links. Although high concentrations of Cr(III) inhibit DNA replication, micromolar concentrations of Cr(III) can substitute for Mg2+, weakly activate the Klenow fragment of E. coli DNA polymerase I (Pol I-KF), and act as an enhancer of nucleotide incorporation. Alterations in enzyme kinetics induced by Cr(III) increase DNA polymerase processivity and the rate of polymerase bypass of DNA lesions. This results in an increased rate of spontaneous mutagenesis during DNA replication both in vitro and in vivo. Our results indicate that chromium(III) may contribute to chromate-induced mutagenesis and may be a factor in the initiation of chromium carcinogenesis."
1290170,Tezuka et al. 1995,In vitro effect of chromium and other trace metals on mouse hepatotoxicity induced by carbon tetrachloride exposure,"Using primary cultured mouse hepatocytes, in vitro study was performed to discuss the effect of Cr(III) and several other trace metals, Cr(VI), Mn(II), Zn(II), Co(II), Cu(II), Ni(II), and Ga(III) on acute liver damage induced by CCl4 exposure. 1) The LDH activity 60 min after CCl4 exposure increased dose-dependently with CCl4 concentrations in all of the trace metal pretreatment groups, except for the Cr(VI) pretreatment group, which showed a significant protective effect even after 30 min of CCl4 exposure. 2) LDH leakage was not observed 10 min after CCl4 exposure at 3 or 5 mM, while lipid peroxidation was increased dose-dependently with CCl4 concentrations in all groups except the Cr(VI) pretreatment group, in which the production of peroxidated lipid was significantly inhibited. 3) Similarly to the pretreatment with Cr(VI), LDH leakage 30 min after exposure to 5 mM CCl4 was inhibited by pretreatment with such antioxidants as N,N'-diphenyl-p-phenylenediamine or DL-alpha-tocopherol. 4) The Cr(VI) uptake was about 50% of the added amount, whereas the Cr(III) uptake was only 5% of the added amount. 5) 90% or more of the intracellular chromium was reduced to Cr(III) 10 min after Cr(VI) treatment. The results suggested that the in vitro protective effect of pretreatment with Cr(VI) was due to a rapid reduction of Cr(VI) to Cr(III), and the radical scavenger-like effect of the produced Cr(III) was the same effect as in vivo Cr(III); it therefore suggests that Cr(III) contributes to protective effect on CCl4-induced hepatotoxicity.","In vitro effect of chromium and other trace metals on mouse hepatotoxicity induced by carbon tetrachloride exposure Abs: Using primary cultured mouse hepatocytes, in vitro study was performed to discuss the effect of Cr(III) and several other trace metals, Cr(VI), Mn(II), Zn(II), Co(II), Cu(II), Ni(II), and Ga(III) on acute liver damage induced by CCl4 exposure. 1) The LDH activity 60 min after CCl4 exposure increased dose-dependently with CCl4 concentrations in all of the trace metal pretreatment groups, except for the Cr(VI) pretreatment group, which showed a significant protective effect even after 30 min of CCl4 exposure. 2) LDH leakage was not observed 10 min after CCl4 exposure at 3 or 5 mM, while lipid peroxidation was increased dose-dependently with CCl4 concentrations in all groups except the Cr(VI) pretreatment group, in which the production of peroxidated lipid was significantly inhibited. 3) Similarly to the pretreatment with Cr(VI), LDH leakage 30 min after exposure to 5 mM CCl4 was inhibited by pretreatment with such antioxidants as N,N'-diphenyl-p-phenylenediamine or DL-alpha-tocopherol. 4) The Cr(VI) uptake was about 50% of the added amount, whereas the Cr(III) uptake was only 5% of the added amount. 5) 90% or more of the intracellular chromium was reduced to Cr(III) 10 min after Cr(VI) treatment. The results suggested that the in vitro protective effect of pretreatment with Cr(VI) was due to a rapid reduction of Cr(VI) to Cr(III), and the radical scavenger-like effect of the produced Cr(III) was the same effect as in vivo Cr(III); it therefore suggests that Cr(III) contributes to protective effect on CCl4-induced hepatotoxicity."
1290169,Sarkar et al. 1993,Differential protection of chlorophyllin against clastogenic effects of chromium and chlordane in mouse bone marrow in vivo,"The anticlastogenic activity of sodium-copper-chlorophyllin was tested against two known clastogens, chromium(VI) oxide and the pesticide chlordane, both of which occur as environmental toxicants. The chemicals were administered to male Swiss albino mice by gavage and chromosomes were studied from bone marrow cells 24 h after the exposure, following colchicine-air drying-Giemsa preparation. The end-points screened were the frequencies of chromosomal aberrations and damaged cells. The clastogenic effects induced by chromium in aqueous solution (20 mg/kg body weight) were reduced to a significant level by chlorophyllin (1.5 mg/kg body weight), when administered both before and simultaneously with the toxicant. The effects of chlordane in olive oil (10 mg/kg body weight) were, however, not reduced by the administration of chlorophyllin (1.5 and 3 mg/kg body weight).","Differential protection of chlorophyllin against clastogenic effects of chromium and chlordane in mouse bone marrow in vivo Abs: The anticlastogenic activity of sodium-copper-chlorophyllin was tested against two known clastogens, chromium(VI) oxide and the pesticide chlordane, both of which occur as environmental toxicants. The chemicals were administered to male Swiss albino mice by gavage and chromosomes were studied from bone marrow cells 24 h after the exposure, following colchicine-air drying-Giemsa preparation. The end-points screened were the frequencies of chromosomal aberrations and damaged cells. The clastogenic effects induced by chromium in aqueous solution (20 mg/kg body weight) were reduced to a significant level by chlorophyllin (1.5 mg/kg body weight), when administered both before and simultaneously with the toxicant. The effects of chlordane in olive oil (10 mg/kg body weight) were, however, not reduced by the administration of chlorophyllin (1.5 and 3 mg/kg body weight)."
1290168,Molyneux and  Davies 1995,Direct evidence for hydroxyl radical-induced damage to nucleic acids by chromium(VI)-derived species: Implications for chromium carcinogenesis,"Reduction of Cr(VI) by NADH and NADPH has been shown to yield Cr(V) species, which have been detected by electron paramagnetic resonance (EPR) spectroscopy. The fine structure on the EPR signal of the Cr(V) species is consistent with the presence of two NAD(P)H ligands in a square-pyramidal arrangement with a single oxygen (oxo) group at the apex. Neither this species nor the initial Cr(VI) complex damage DNA components as evidenced by the lack of effect of these compounds on the optical and EPR signals of the Cr(VI) and Cr(V) species respectively. Addition of hydrogen peroxide to the Cr(V) species is shown to result in the formation of a further transient EPR signal, the parameters of which are consistent with an assignment to a Cr(V)-peroxide complex. Inclusion of the spin trap 5,5-dimethyl-1-pyrroline-N-oxide in this system demonstrates that hydroxyl radicals are also generated, possibly via the decomposition of the peroxide complex. Inclusion of DNA components in this system together with the spin trap 2-methyl-2-nitrosopropane results in the detection of base- and sugar-derived radicals; the characteristic EPR signals of these species have allowed both the identification of these species and their mechanism of formation to be determined. The signals from the former species are consistent with radical addition to the base, whereas the sugar-derived species are believed to be formed via hydrogen atom abstraction. In each case, this behaviour is consistent with hydroxyl radicals being the damaging species in systems where Cr(V) is generated in the presence of hydrogen peroxide. These results therefore suggest that it may be the hydroxyl radical that is the ultimate carcinogenic species in cells and systems exposed to Cr(VI).","Direct evidence for hydroxyl radical-induced damage to nucleic acids by chromium(VI)-derived species: Implications for chromium carcinogenesis Abs: Reduction of Cr(VI) by NADH and NADPH has been shown to yield Cr(V) species, which have been detected by electron paramagnetic resonance (EPR) spectroscopy. The fine structure on the EPR signal of the Cr(V) species is consistent with the presence of two NAD(P)H ligands in a square-pyramidal arrangement with a single oxygen (oxo) group at the apex. Neither this species nor the initial Cr(VI) complex damage DNA components as evidenced by the lack of effect of these compounds on the optical and EPR signals of the Cr(VI) and Cr(V) species respectively. Addition of hydrogen peroxide to the Cr(V) species is shown to result in the formation of a further transient EPR signal, the parameters of which are consistent with an assignment to a Cr(V)-peroxide complex. Inclusion of the spin trap 5,5-dimethyl-1-pyrroline-N-oxide in this system demonstrates that hydroxyl radicals are also generated, possibly via the decomposition of the peroxide complex. Inclusion of DNA components in this system together with the spin trap 2-methyl-2-nitrosopropane results in the detection of base- and sugar-derived radicals; the characteristic EPR signals of these species have allowed both the identification of these species and their mechanism of formation to be determined. The signals from the former species are consistent with radical addition to the base, whereas the sugar-derived species are believed to be formed via hydrogen atom abstraction. In each case, this behaviour is consistent with hydroxyl radicals being the damaging species in systems where Cr(V) is generated in the presence of hydrogen peroxide. These results therefore suggest that it may be the hydroxyl radical that is the ultimate carcinogenic species in cells and systems exposed to Cr(VI)."
1290167,da Cruz Fresco et al. 1995,The reductive conversion of chromium (VI) by ascorbate gives rise to apurinic/apyrimidinic sites in isolated DNA,"The formation of apurinic/apyrimidinic sites (AP-sites) and single strand breaks (SSB) by chromate and ascorbate (AsA) in isolated DNA was investigated using a number of agents that cleave DNA at AP-sites (putrescine, exonuclease III, the tripeptide Lys-Trp-Lys, and an AP-endonuclease containing fraction isolated from human fibroblasts). Relative to the number of SSB caused by chromate and AsA alone, all these agents induced additional nicking, indicating the induction of AP-sites. Chromate/AsA-induced AP-sites contain aldehyde groups, as cleavage by putrescine could be prevented by treatment with borohydride which reduced the aldehyde. The time course for the formation of both DNA lesions was very similar, and there was a 1:1 ratio of the number of SSB to the number of AP-sites. The addition of catalase to incubation mixtures containing chromate/AsA led to an almost complete suppression of AP-sites and SSB. In systems containing lower concentrations of chromate/AsA, the exclusion of oxygen inhibited the formation of both lesions. It is suggested that AP-sites and SSB arise from attack by reactive species deriving from chromate/AsA on one single site at DNA, probably the sugar moiety. In view of the known mutagenicity of AP-sites, these results could aid an understanding of the mechanisms underlying chromium(VI) carcinogenicity.","The reductive conversion of chromium (VI) by ascorbate gives rise to apurinic/apyrimidinic sites in isolated DNA Abs: The formation of apurinic/apyrimidinic sites (AP-sites) and single strand breaks (SSB) by chromate and ascorbate (AsA) in isolated DNA was investigated using a number of agents that cleave DNA at AP-sites (putrescine, exonuclease III, the tripeptide Lys-Trp-Lys, and an AP-endonuclease containing fraction isolated from human fibroblasts). Relative to the number of SSB caused by chromate and AsA alone, all these agents induced additional nicking, indicating the induction of AP-sites. Chromate/AsA-induced AP-sites contain aldehyde groups, as cleavage by putrescine could be prevented by treatment with borohydride which reduced the aldehyde. The time course for the formation of both DNA lesions was very similar, and there was a 1:1 ratio of the number of SSB to the number of AP-sites. The addition of catalase to incubation mixtures containing chromate/AsA led to an almost complete suppression of AP-sites and SSB. In systems containing lower concentrations of chromate/AsA, the exclusion of oxygen inhibited the formation of both lesions. It is suggested that AP-sites and SSB arise from attack by reactive species deriving from chromate/AsA on one single site at DNA, probably the sugar moiety. In view of the known mutagenicity of AP-sites, these results could aid an understanding of the mechanisms underlying chromium(VI) carcinogenicity."
1290163,Cole and  Merletti 1980,Chemical agents and occupational cancer,,Chemical agents and occupational cancer Abs: 
1290160,Stern 1983,In vitro assessment of equivalence of occupational health risk: welders,"The possibility of using in vitro testing to determine the equivalence of risk for various occupational groups is discussed. In the absence of epidemiological evidence or relevant animal in vivo bioassays on which to determine the health effects of specific occupational exposures, it is proposed to use similarities in the in vitro response to substances with known (or strongly suspected) and unknown risk to demonstrate their risk equivalence. Identification and evaluation of a high risk &quot;hot spot&quot; due to exposure to Cr(VI) for stainless steel welders is discussed in terms of recent developments in collection, analysis and bioassay of welding fumes.","In vitro assessment of equivalence of occupational health risk: welders Abs: The possibility of using in vitro testing to determine the equivalence of risk for various occupational groups is discussed. In the absence of epidemiological evidence or relevant animal in vivo bioassays on which to determine the health effects of specific occupational exposures, it is proposed to use similarities in the in vitro response to substances with known (or strongly suspected) and unknown risk to demonstrate their risk equivalence. Identification and evaluation of a high risk &quot;hot spot&quot; due to exposure to Cr(VI) for stainless steel welders is discussed in terms of recent developments in collection, analysis and bioassay of welding fumes."
1290155,Hicks et al. 1987,"Cytotoxic, irritant and fibrogenic effects of metal-fume particulate materials investigated by intramuscular injection in the rat and guinea pig","The cytotoxic, irritant, and fibrogenic effects of intramuscular administration of ferrochromium fume particles from electric arc welding processes were investigated. Particles containing iron (7439896), nickel (7440020), manganese (7439965), chromium (7440473) and other steel and flux constituents were collected during welding with various types of electrodes. Female albino-guinea-pigs or male albino-CSE-rats were injected in the vastus lateralis muscle in dose volumes of 0.1 milliliter with test material concentrations of 1, 10, or 100mg/ml. The animals were killed at intervals of 2 days to 8 weeks, and the injected muscles examined visually and microscopically. Irritant or fibrogenic effects consisting of macrophage granulomata and fibrotic granulation were present for test samples from all electrodes. Particles from manual metal arc stainless steel electrodes caused severe local inflammation and vigorous development of collagenous granulation tissue and dead muscle fibers. Particles from two other electrodes were less toxic, less irritant, and less fibrogenic, but they provoked formation of granulomatous nodules. Very little irritancy or toxicity was shown by a sample from a flux free, metal inert gas stainless steel electrode. Injections of insoluble metal oxides of iron, chromium, or titanium (7440326) were benign. No irritant, fibrogenic, or toxic effects were found, and phagocytosis was very effective, showing that the test was nondiscriminating. The authors conclude that the fibrogenicity, irritancy, and toxicity observed were associated with hexavalent chromium (18540299) or perhaps with flux components such as alkaline oxides or silica (7631869).","Cytotoxic, irritant and fibrogenic effects of metal-fume particulate materials investigated by intramuscular injection in the rat and guinea pig Abs: The cytotoxic, irritant, and fibrogenic effects of intramuscular administration of ferrochromium fume particles from electric arc welding processes were investigated. Particles containing iron (7439896), nickel (7440020), manganese (7439965), chromium (7440473) and other steel and flux constituents were collected during welding with various types of electrodes. Female albino-guinea-pigs or male albino-CSE-rats were injected in the vastus lateralis muscle in dose volumes of 0.1 milliliter with test material concentrations of 1, 10, or 100mg/ml. The animals were killed at intervals of 2 days to 8 weeks, and the injected muscles examined visually and microscopically. Irritant or fibrogenic effects consisting of macrophage granulomata and fibrotic granulation were present for test samples from all electrodes. Particles from manual metal arc stainless steel electrodes caused severe local inflammation and vigorous development of collagenous granulation tissue and dead muscle fibers. Particles from two other electrodes were less toxic, less irritant, and less fibrogenic, but they provoked formation of granulomatous nodules. Very little irritancy or toxicity was shown by a sample from a flux free, metal inert gas stainless steel electrode. Injections of insoluble metal oxides of iron, chromium, or titanium (7440326) were benign. No irritant, fibrogenic, or toxic effects were found, and phagocytosis was very effective, showing that the test was nondiscriminating. The authors conclude that the fibrogenicity, irritancy, and toxicity observed were associated with hexavalent chromium (18540299) or perhaps with flux components such as alkaline oxides or silica (7631869)."
1290154,Lee 1987,Health assessment of chromium,"Attention is focused in this paper on those health effects whose significance may have been overlooked in previous evaluations of the United States Environmental Protection Agency's database for regulatory purposes of chromium (7440473) and chromium compounds. While there is no controversy on the carcinogenic properties of hexavalent chromium compounds, depending on which set of data one chooses as a basis for risk analysis, diverse risk numbers can be developed. Using the IARC classification scheme, the level of carcinogenic evidence available for the combined animal and human data would place hexavalent chromium compounds into Group 1, a human carcinogen. Noncarcinogenic effects include hypersensitivity. However, there are few data available on the exposure concentration needed to induce an allergic response. Workers exposed to vapors of boiling dichromate solutions have developed acute contact dermatitis. The toxic effects of occupational exposure to inhaled chromium have most often been ulceration and perforation of the nasal septum. Severe irritation of the throat and lower regions of the respiratory tract have been linked with chromium levels as low as 120 micrograms/cubic meter. The authors conclude that there is enough data available to substantiate that the atmospheres in chrome plating shops and those of stainless steel welding shops can cause degeneration of nasal septa, other disorders of the upper respiratory system, and significant reductions in pulmonary function.","Health assessment of chromium Abs: Attention is focused in this paper on those health effects whose significance may have been overlooked in previous evaluations of the United States Environmental Protection Agency's database for regulatory purposes of chromium (7440473) and chromium compounds. While there is no controversy on the carcinogenic properties of hexavalent chromium compounds, depending on which set of data one chooses as a basis for risk analysis, diverse risk numbers can be developed. Using the IARC classification scheme, the level of carcinogenic evidence available for the combined animal and human data would place hexavalent chromium compounds into Group 1, a human carcinogen. Noncarcinogenic effects include hypersensitivity. However, there are few data available on the exposure concentration needed to induce an allergic response. Workers exposed to vapors of boiling dichromate solutions have developed acute contact dermatitis. The toxic effects of occupational exposure to inhaled chromium have most often been ulceration and perforation of the nasal septum. Severe irritation of the throat and lower regions of the respiratory tract have been linked with chromium levels as low as 120 micrograms/cubic meter. The authors conclude that there is enough data available to substantiate that the atmospheres in chrome plating shops and those of stainless steel welding shops can cause degeneration of nasal septa, other disorders of the upper respiratory system, and significant reductions in pulmonary function."
1290153,Bencko 1985,Chromium: a review of environmental and occupational toxicology,"The following topics are covered in this brief review on the environmental and occupational toxicology of chromium: occurrence, production and uses of chromium and chromium compounds; experimental toxicology; chromium toxicity for man; hygienic and ecologic aspects of chromium contamination of the environment. The review provides a conclusive evidence which suggests that chromium, especially its hexavalent form, is both toxic and carcinogenic, but its trivalent form is physiologically essential in the metabolism of insulin. It is also emphasized that among the major sources of environmental chromium today are the cement industry and the increasingly widespread use of chromium compounds added as an anticorrosion admixture to a variety of cooling systems, e.g. in large power plants, which may greatly contribute to the overall pollution of outdoor air at the sites.","Chromium: a review of environmental and occupational toxicology Abs: The following topics are covered in this brief review on the environmental and occupational toxicology of chromium: occurrence, production and uses of chromium and chromium compounds; experimental toxicology; chromium toxicity for man; hygienic and ecologic aspects of chromium contamination of the environment. The review provides a conclusive evidence which suggests that chromium, especially its hexavalent form, is both toxic and carcinogenic, but its trivalent form is physiologically essential in the metabolism of insulin. It is also emphasized that among the major sources of environmental chromium today are the cement industry and the increasingly widespread use of chromium compounds added as an anticorrosion admixture to a variety of cooling systems, e.g. in large power plants, which may greatly contribute to the overall pollution of outdoor air at the sites."
1290152,Uyeki et al. 1986,Chromium effects on chondrocytic differentiation in vitro,"A tissue culture study was conducted on the effects of chromium on chondrocytic differentiation. Mesenchymal cells from stage 22-24 chick limb buds were dispersed and cultured as micromasses, where they differentiated into chondrocytes. Addition of chromium(VI) to the cultures indicated that the production of proteoglycans (as detected by Alcian blue staining) was more sensitive to chromium's effects than was cell proliferation. Whereas Alcian blue nodule formation was inhibited by 1 microM Cr(VI), cell proliferation (as detected by cell counts) was not. Chromium (VI) was added to cultures at daily intervals, and these studies indicated that the interval of d 1-2 was the most sensitive period. ADP-ribose transferase activity in these cultures was measured; the pattern of enzyme activity in control cultures was high 1 and 24 h after the start of culture, decreased abruptly between 24 and 48 h, and then decreased more gradually. In the presence of Cr(VI), elevated ADP-ribose transferase levels were maintained throughout the culture period. We suggest that, in presence of 1.0 microM chromium(VI) or higher concentrations, the balance of events favors nucleolytic action rather than repair of damage.","Chromium effects on chondrocytic differentiation in vitro Abs: A tissue culture study was conducted on the effects of chromium on chondrocytic differentiation. Mesenchymal cells from stage 22-24 chick limb buds were dispersed and cultured as micromasses, where they differentiated into chondrocytes. Addition of chromium(VI) to the cultures indicated that the production of proteoglycans (as detected by Alcian blue staining) was more sensitive to chromium's effects than was cell proliferation. Whereas Alcian blue nodule formation was inhibited by 1 microM Cr(VI), cell proliferation (as detected by cell counts) was not. Chromium (VI) was added to cultures at daily intervals, and these studies indicated that the interval of d 1-2 was the most sensitive period. ADP-ribose transferase activity in these cultures was measured; the pattern of enzyme activity in control cultures was high 1 and 24 h after the start of culture, decreased abruptly between 24 and 48 h, and then decreased more gradually. In the presence of Cr(VI), elevated ADP-ribose transferase levels were maintained throughout the culture period. We suggest that, in presence of 1.0 microM chromium(VI) or higher concentrations, the balance of events favors nucleolytic action rather than repair of damage."
1290151,Kortenkamp et al. 1989,Generation of PM2 DNA breaks in the course of reduction of chromium(VI) by glutathione,"The carcinogen chromate is efficiently taken up and reduced to chromium(III) compounds by various biological systems. To test the possible DNA damage induced in the course of chromium(VI) reduction, we used a combination of chromate with the reductant glutathione (GSH) as well as a green complex of chromium(V), which is formed in the reaction of chromate with GSH. The combination of chromate and glutathione was found to cause single-strand breaks in supercoiled circular DNA of the bacteriophage PM2. The green chromium(V) complex Na4(GSH)4Cr(V).8H2O, prepared from chromate and glutathione, also cleaved supercoiled PM2 DNA. No DNA-degrading effects were observed with either chromate or the final product of the reaction with GSH, a purple anionic chromium(III) GSH complex. The nature of the buffering agents revealed a strong influence on the extent of DNA strand breaks produced by chromate and GSH. A variation of the GSH concentration in the reaction with chromate and PM2 DNA, performed in sodium phosphate-buffered solutions showed an initial increase in the number of strand breaks at GSH concentrations up to 1 mM followed by a decline at higher GSH concentrations. Since neither chromate, when administered individually, nor the final product of chromium(VI) reduction, the purple chromium(III) GSH complex, produced any detectable DNA cleavage, the critical steps leading to DNA strand breaks occur in the course of the conversion of chromium(VI) to chromium(III) by GSH, the most abundant intracellular low molecular thiol. Moreover, the demonstration that DNA cleavage is induced in the presence of the chromium(V) complex identifies chromium(V) as the oxidation state of the metal, which is involved in the steps leading to DNA-damaging effects of chromate.","Generation of PM2 DNA breaks in the course of reduction of chromium(VI) by glutathione Abs: The carcinogen chromate is efficiently taken up and reduced to chromium(III) compounds by various biological systems. To test the possible DNA damage induced in the course of chromium(VI) reduction, we used a combination of chromate with the reductant glutathione (GSH) as well as a green complex of chromium(V), which is formed in the reaction of chromate with GSH. The combination of chromate and glutathione was found to cause single-strand breaks in supercoiled circular DNA of the bacteriophage PM2. The green chromium(V) complex Na4(GSH)4Cr(V).8H2O, prepared from chromate and glutathione, also cleaved supercoiled PM2 DNA. No DNA-degrading effects were observed with either chromate or the final product of the reaction with GSH, a purple anionic chromium(III) GSH complex. The nature of the buffering agents revealed a strong influence on the extent of DNA strand breaks produced by chromate and GSH. A variation of the GSH concentration in the reaction with chromate and PM2 DNA, performed in sodium phosphate-buffered solutions showed an initial increase in the number of strand breaks at GSH concentrations up to 1 mM followed by a decline at higher GSH concentrations. Since neither chromate, when administered individually, nor the final product of chromium(VI) reduction, the purple chromium(III) GSH complex, produced any detectable DNA cleavage, the critical steps leading to DNA strand breaks occur in the course of the conversion of chromium(VI) to chromium(III) by GSH, the most abundant intracellular low molecular thiol. Moreover, the demonstration that DNA cleavage is induced in the presence of the chromium(V) complex identifies chromium(V) as the oxidation state of the metal, which is involved in the steps leading to DNA-damaging effects of chromate."
1290150,Mutti et al. 1985,Urinary excretion of brush-border antigen revealed by monoclonal antibody: early indicator of toxic nephropathy,Mouse monoclonal antibodies against brush-border antigens of the proximal tubule of human kidney were produced by the hybridisation technique. The urinary excretion of a brush-border protein with an apparent molecular weight of 50 000 (BB-50) was measured by a sandwich enzyme-linked immunosorbent assay with a mouse IgG1 against BB-50 and a polyclonal rabbit antiserum against human kidney as coating and second antibodies. The urinary excretion of BB-50 was fifty times higher in patients treated with cisplatin than in a matched control group and twice as high in workers occupationally exposed to water-soluble chromium(VI) compounds as in their matched controls. These findings suggest that the urinary excretion of kidney antigens revealed by monoclonal antibodies is a very sensitive and specific test for the assessment of toxic nephropathies.,Urinary excretion of brush-border antigen revealed by monoclonal antibody: early indicator of toxic nephropathy Abs: Mouse monoclonal antibodies against brush-border antigens of the proximal tubule of human kidney were produced by the hybridisation technique. The urinary excretion of a brush-border protein with an apparent molecular weight of 50 000 (BB-50) was measured by a sandwich enzyme-linked immunosorbent assay with a mouse IgG1 against BB-50 and a polyclonal rabbit antiserum against human kidney as coating and second antibodies. The urinary excretion of BB-50 was fifty times higher in patients treated with cisplatin than in a matched control group and twice as high in workers occupationally exposed to water-soluble chromium(VI) compounds as in their matched controls. These findings suggest that the urinary excretion of kidney antigens revealed by monoclonal antibodies is a very sensitive and specific test for the assessment of toxic nephropathies.
1290149,Wolf et al. 1989,Differing effects of chromium(III) and chromium(VI) on nucleotides and DNA,"The formation of complexes from nucleotide diphosphates and triphosphates with trivalent and hexavalent chromium (7440473) (Cr) ions was studied by use of phosphorus-31 nuclear magnetic resonance (NMR) spectroscopy, and the influence of chromium(III) Cr(III) on the melting properties of nucleic acids was examined. Chemical downfield shifts of the phosphate groups, indicating complex formation, were determined for complexes of Cr(III) with ATP, adenosine-5'-diphosphate, deoxyadenosine-5'-triphosphate, guanosine-5'-triphosphate (GTP), guanosine-5'-diphosphate, and cytosine-5'-triphosphate (CTP): for the complex of magnesium(II) (Mg(II)) with ATP as a reference; and for the complex of Cr(III), generated by glutathione reduction of chromium(VI) Cr(VI), with ATP. Binding of Cr(III) to ATP was stronger than its binding to GTP or CTP. The gamma phosphate group was the most affected by the metal ion in the Cr(III) ATP complexes, whereas the beta phosphate group was the most affected in the Mg(II) ATP complexes. The effects of different concentrations of Cr(III) on the melting temperatures of calf thymus DNA, polyadenylic-polyuridylic-acid, and polyguanylic-polycytidylic-acid (PGPCA) were determined. The melting temperatures increased with increased Cr(III) concentration, and the effects were the most pronounced with PGPCA.","Differing effects of chromium(III) and chromium(VI) on nucleotides and DNA Abs: The formation of complexes from nucleotide diphosphates and triphosphates with trivalent and hexavalent chromium (7440473) (Cr) ions was studied by use of phosphorus-31 nuclear magnetic resonance (NMR) spectroscopy, and the influence of chromium(III) Cr(III) on the melting properties of nucleic acids was examined. Chemical downfield shifts of the phosphate groups, indicating complex formation, were determined for complexes of Cr(III) with ATP, adenosine-5'-diphosphate, deoxyadenosine-5'-triphosphate, guanosine-5'-triphosphate (GTP), guanosine-5'-diphosphate, and cytosine-5'-triphosphate (CTP): for the complex of magnesium(II) (Mg(II)) with ATP as a reference; and for the complex of Cr(III), generated by glutathione reduction of chromium(VI) Cr(VI), with ATP. Binding of Cr(III) to ATP was stronger than its binding to GTP or CTP. The gamma phosphate group was the most affected by the metal ion in the Cr(III) ATP complexes, whereas the beta phosphate group was the most affected in the Mg(II) ATP complexes. The effects of different concentrations of Cr(III) on the melting temperatures of calf thymus DNA, polyadenylic-polyuridylic-acid, and polyguanylic-polycytidylic-acid (PGPCA) were determined. The melting temperatures increased with increased Cr(III) concentration, and the effects were the most pronounced with PGPCA."
1290148,Hathaway 1989,Role of epidemiologic studies in evaluating the carcinogenicity of chromium compounds,"Epidemiologic and animal studies have identified intermediately-soluble chromates as human carcinogens. Epidemiologic studies also provide moderately strong evidence to conclude that chromates do not cause cancer at sites other than the respiratory tract. This information, combined with the evidence from animal studies and in vitro experiments, has led to the conclusion that chromates do not present a carcinogenic risk from ingestion. Unfortunately, epidemiologic studies have not provided definitive answers to other questions: (i) does trivalent chromium present a cancer risk?; (ii) is there a threshold for carcinogenic effects?; and (iii) what is the appropriate model for predicting cancer risk? Mechanistic research with supporting evidence from animal studies has provided the most useful information to answer these questions. Working hypotheses are: (i) trivalent chromium is not a carcinogen; (ii) there are probably substantial differences in carcinogenic potency between chromates, with the water-soluble compounds having lower potency than intermediately-soluble compounds; (iii) only respiratory tract cancers are caused by exposure to chromates, and ingestion and chromates does not constitute a carcinogenic risk; (iv) there is probably a threshold for carcinogenic effects from chromium due to detoxification mechanisms and lack of bioavailability of low doses; and (v) currently used models for quantitative risk assessment (e.g. the low dose linearized multi-stage model) are inappropriate to predict low dose cancer risks from exposure to chromates.","Role of epidemiologic studies in evaluating the carcinogenicity of chromium compounds Abs: Epidemiologic and animal studies have identified intermediately-soluble chromates as human carcinogens. Epidemiologic studies also provide moderately strong evidence to conclude that chromates do not cause cancer at sites other than the respiratory tract. This information, combined with the evidence from animal studies and in vitro experiments, has led to the conclusion that chromates do not present a carcinogenic risk from ingestion. Unfortunately, epidemiologic studies have not provided definitive answers to other questions: (i) does trivalent chromium present a cancer risk?; (ii) is there a threshold for carcinogenic effects?; and (iii) what is the appropriate model for predicting cancer risk? Mechanistic research with supporting evidence from animal studies has provided the most useful information to answer these questions. Working hypotheses are: (i) trivalent chromium is not a carcinogen; (ii) there are probably substantial differences in carcinogenic potency between chromates, with the water-soluble compounds having lower potency than intermediately-soluble compounds; (iii) only respiratory tract cancers are caused by exposure to chromates, and ingestion and chromates does not constitute a carcinogenic risk; (iv) there is probably a threshold for carcinogenic effects from chromium due to detoxification mechanisms and lack of bioavailability of low doses; and (v) currently used models for quantitative risk assessment (e.g. the low dose linearized multi-stage model) are inappropriate to predict low dose cancer risks from exposure to chromates."
1290146,Friess 1989,Carcinogenic risk assessment criteria associated with inhalation of airborne particulates containing chromium (VI/III),"Contaminated land sites and unused chromate production facilities raise the possibility that remediation operations could involve generation of airborne particles of respirable size containing both Cr(VI) and Cr(III) in soluble and insoluble forms. These airborne particles reaching human populations in the neighborhoods involved, can pose carcinogenic risks via Cr(VI)-containing material retained in the lungs. It is proposed that the risk assessment process for this inhalation exposure be governed by the following considerations. (i) Only the respirable fraction (0.2-10.0 microns diameters) of the inhaled particulates should be considered as contributing to delivered dosage of Cr(VI) to the lung. (ii) In accordance with the ICRP analysis of particulate retention in the lung for extended intervals, the airborne respirable particle intake should be multiplied by the factor 0.125 to generate an estimate of dosage of particles retained in the lung for extended intervals, leading to possible carcinogenesis from the Cr(VI) content. And (iii), the inhalation carcinogenic risk for Cr(VI) should only be modelled in increments above a daily total chromium intake of 100 micrograms per day, a current estimate of the required daily intake of this essential mineral.","Carcinogenic risk assessment criteria associated with inhalation of airborne particulates containing chromium (VI/III) Abs: Contaminated land sites and unused chromate production facilities raise the possibility that remediation operations could involve generation of airborne particles of respirable size containing both Cr(VI) and Cr(III) in soluble and insoluble forms. These airborne particles reaching human populations in the neighborhoods involved, can pose carcinogenic risks via Cr(VI)-containing material retained in the lungs. It is proposed that the risk assessment process for this inhalation exposure be governed by the following considerations. (i) Only the respirable fraction (0.2-10.0 microns diameters) of the inhaled particulates should be considered as contributing to delivered dosage of Cr(VI) to the lung. (ii) In accordance with the ICRP analysis of particulate retention in the lung for extended intervals, the airborne respirable particle intake should be multiplied by the factor 0.125 to generate an estimate of dosage of particles retained in the lung for extended intervals, leading to possible carcinogenesis from the Cr(VI) content. And (iii), the inhalation carcinogenic risk for Cr(VI) should only be modelled in increments above a daily total chromium intake of 100 micrograms per day, a current estimate of the required daily intake of this essential mineral."
1290145,Shi and  Dalal 1989,Chromium (V) and hydroxyl radical formation during the glutathione reductase-catalyzed reduction of chromium (VI),Electron spin resonance measurements provide evidence for the formation of long-lived Cr(V) intermediates in the reduction of Cr(VI) by glutathione reductase in the presence of NADPH and for the hydroxyl radical formation during the glutathione reductase catalyzed reduction of Cr(VI). Hydrogen peroxide suppresses Cr(V) and enhances the formation of hydroxyl radicals. Thus Cr(V) intermediates catalyze generation of hydroxyl radicals from hydrogen peroxide through a Fenton-like reaction. Thus the mechanism of Cr(VI) toxicity might involve the interaction between macromolecules and the hydroxyl radicals.,Chromium (V) and hydroxyl radical formation during the glutathione reductase-catalyzed reduction of chromium (VI) Abs: Electron spin resonance measurements provide evidence for the formation of long-lived Cr(V) intermediates in the reduction of Cr(VI) by glutathione reductase in the presence of NADPH and for the hydroxyl radical formation during the glutathione reductase catalyzed reduction of Cr(VI). Hydrogen peroxide suppresses Cr(V) and enhances the formation of hydroxyl radicals. Thus Cr(V) intermediates catalyze generation of hydroxyl radicals from hydrogen peroxide through a Fenton-like reaction. Thus the mechanism of Cr(VI) toxicity might involve the interaction between macromolecules and the hydroxyl radicals.
1290143,Kawanishi et al. 1989,Hydroxyl radical and singlet oxygen production and DNA damage induced by carcinogenic metal compounds and hydrogen peroxide,Biosis copyright: biol abs. rrm human,Hydroxyl radical and singlet oxygen production and DNA damage induced by carcinogenic metal compounds and hydrogen peroxide Abs: Biosis copyright: biol abs. rrm human
1290142,Bravo et al. 1990,Differential effects of eight metal ions on lymphocyte differentiation antigens in vitro,"In vitro studies were conducted to determine the effects of metal ions known to be released from metallic implants in vivo on the expression of lymphocyte surface antigens. Normal human peripheral blood lymphocytes were exposed to various concentrations of metal ions (Fe3+, Ni2+, Co2+, Mo6+, V5+, Cr6+, Cr3+, and Ti3+) for 30 min at 37 degrees C in a 5% CO2 atmosphere, and then analyzed for their ability to form rosettes with sheep red blood cells. Following this preliminary analysis, lymphocytes were exposed to the metal ions found to inhibit the E-rosette reaction (Fe3+, Ni2+, and Co2+) in order to determine which of the following surface antigens were affected: CD2, CD3, CD4, CD8, CD1, CD22, CD10, and HLA-DR. Our results showed that the in vitro treatment of lymphocytes with Fe3+ or Co2+ caused inhibition of CD2 only, whereas Ni2+ caused inhibition of both CD2 and CD3 antigens. These findings suggest that Fe3+, Co2+, and Ni2+ ions may interfere with T cell activation since both CD2 and CD3 are involved in that process.","Differential effects of eight metal ions on lymphocyte differentiation antigens in vitro Abs: In vitro studies were conducted to determine the effects of metal ions known to be released from metallic implants in vivo on the expression of lymphocyte surface antigens. Normal human peripheral blood lymphocytes were exposed to various concentrations of metal ions (Fe3+, Ni2+, Co2+, Mo6+, V5+, Cr6+, Cr3+, and Ti3+) for 30 min at 37 degrees C in a 5% CO2 atmosphere, and then analyzed for their ability to form rosettes with sheep red blood cells. Following this preliminary analysis, lymphocytes were exposed to the metal ions found to inhibit the E-rosette reaction (Fe3+, Ni2+, and Co2+) in order to determine which of the following surface antigens were affected: CD2, CD3, CD4, CD8, CD1, CD22, CD10, and HLA-DR. Our results showed that the in vitro treatment of lymphocytes with Fe3+ or Co2+ caused inhibition of CD2 only, whereas Ni2+ caused inhibition of both CD2 and CD3 antigens. These findings suggest that Fe3+, Co2+, and Ni2+ ions may interfere with T cell activation since both CD2 and CD3 are involved in that process."
1290141,Fleet et al. 1990,Induction of hepatic metallothionein by intraperitoneal metal injection: An associated inflammatory response,"The nature of hepatic metallothionein (MT) induction by several metals and its relationship to an inflammatory response was studied in chicks. Intraperitoneal (ip) injection of chromium (Cr), managanese, and iron (Fe) caused a much greater increase in hepatic MT (10.2-, 9.0-, and 6.8-fold) compared with cobalt and nickel (2.5- and 2.9-fold); thus not all transition metals are effective. Cr3+ caused markedly greater hepatic MT accumulation than Cr6+, suggesting that the ionic nature of the metal is an important factor. Small organic complexes of Fe (ferrous gluconate or lactate, 6.2-fold) caused significantly greater accumulation of hepatic MT than ferric dextran (1.4-fold), a large organic aggregate. In vitro data from chick hepatocytes and/or fibroblasts clearly indicated that Fe does not effect the induction of MT directly. The role of inflammation, as measured by recruitment of peritoneal exudate cells (PEC), was examined. Endotoxin (LPS), Sephadex (S), and Fe elicited significant elevations in PEC number at 24 h posttreatment (S), and Fe elicited significant elevations in PEC number at 24 h posttreatment (S = Fe greater than LPS much greater than control). The percentage of heterophils but not macrophages was significantly correlated with the accumulation and induction of hepatic MT. In a similar experiment with Cr, we demonstrated that Cr3+ but not Cr6+ stimulated MT messenger RNA accumulation and concomitant hetereophil infiltration at 3 h after injection. Our results indicate that the induction of hepatic MT by the parenteral administration of a number of metals is dependent on the chemical nature of the metal and is associated with an inflammatory response.","Induction of hepatic metallothionein by intraperitoneal metal injection: An associated inflammatory response Abs: The nature of hepatic metallothionein (MT) induction by several metals and its relationship to an inflammatory response was studied in chicks. Intraperitoneal (ip) injection of chromium (Cr), managanese, and iron (Fe) caused a much greater increase in hepatic MT (10.2-, 9.0-, and 6.8-fold) compared with cobalt and nickel (2.5- and 2.9-fold); thus not all transition metals are effective. Cr3+ caused markedly greater hepatic MT accumulation than Cr6+, suggesting that the ionic nature of the metal is an important factor. Small organic complexes of Fe (ferrous gluconate or lactate, 6.2-fold) caused significantly greater accumulation of hepatic MT than ferric dextran (1.4-fold), a large organic aggregate. In vitro data from chick hepatocytes and/or fibroblasts clearly indicated that Fe does not effect the induction of MT directly. The role of inflammation, as measured by recruitment of peritoneal exudate cells (PEC), was examined. Endotoxin (LPS), Sephadex (S), and Fe elicited significant elevations in PEC number at 24 h posttreatment (S), and Fe elicited significant elevations in PEC number at 24 h posttreatment (S = Fe greater than LPS much greater than control). The percentage of heterophils but not macrophages was significantly correlated with the accumulation and induction of hepatic MT. In a similar experiment with Cr, we demonstrated that Cr3+ but not Cr6+ stimulated MT messenger RNA accumulation and concomitant hetereophil infiltration at 3 h after injection. Our results indicate that the induction of hepatic MT by the parenteral administration of a number of metals is dependent on the chemical nature of the metal and is associated with an inflammatory response."
1290140,Sehlmeyer et al. 1990,Accumulation of chromium in Chinese hamster V79-cells and nuclei,"The bioavailability of carcinogenic compounds plays an important role in the process of oncogenesis. Chromium in its hexavalent oxidation state is classified as carcinogen to humans. Therefore we studied the uptake of chromate(VI) into Chinese hamster V79 cells and nuclei isolated after the incubation of the whole cells with chromate. The chromium content of cells and nuclei was determined by atomic absorption spectroscopy. Chromate is taken up in a concentration dependent manner and accumulates to about 30 fold over the extracellular concentration of 0.1 mmol/l. Incubating whole cells with the same concentration results in an intranuclear concentration of up to 6 mmol/l after 3 h. The kinetic parameters (KM = 0.34 mmol/l, Vmax = 0.12 fmol per cell and minute) are in the same order of magnitude as previously published data. The consequences of the high intracellular and intranuclear concentrations are discussed in terms of the genotoxic effects.","Accumulation of chromium in Chinese hamster V79-cells and nuclei Abs: The bioavailability of carcinogenic compounds plays an important role in the process of oncogenesis. Chromium in its hexavalent oxidation state is classified as carcinogen to humans. Therefore we studied the uptake of chromate(VI) into Chinese hamster V79 cells and nuclei isolated after the incubation of the whole cells with chromate. The chromium content of cells and nuclei was determined by atomic absorption spectroscopy. Chromate is taken up in a concentration dependent manner and accumulates to about 30 fold over the extracellular concentration of 0.1 mmol/l. Incubating whole cells with the same concentration results in an intranuclear concentration of up to 6 mmol/l after 3 h. The kinetic parameters (KM = 0.34 mmol/l, Vmax = 0.12 fmol per cell and minute) are in the same order of magnitude as previously published data. The consequences of the high intracellular and intranuclear concentrations are discussed in terms of the genotoxic effects."
1290139,Shi and  Dalal 1990,NADPH-dependent flavoenzymes catalyze one electron reduction of metal ions and molecular oxygen and generate hydroxyl radicals,"This study reports a new property of the important NAD(P)H-dependent flavoenzymes, glutathione reductase, lipoyl dehydrogenase and ferredoxin-NADP+ oxidoreductase, that can catalyze a one electron reduction of metal ions such as chromium(VI) and vanadium(V). During the enzymatic reduction process, molecular oxygen is reduced to H2O2, which reacts with the reduced metal complexes to generate hydroxyl radicals. Since the hydroxyl radicals have been suggested to play an important role in Cr(VI) toxicity, this study provides a basis for a recent observation that Cr(VI) mutagenesis is strongly oxygen dependent. These results also point to an enzymatic pathway for the metabolism of some metal ions and concomitant generation of hydroxyl radicals.","NADPH-dependent flavoenzymes catalyze one electron reduction of metal ions and molecular oxygen and generate hydroxyl radicals Abs: This study reports a new property of the important NAD(P)H-dependent flavoenzymes, glutathione reductase, lipoyl dehydrogenase and ferredoxin-NADP+ oxidoreductase, that can catalyze a one electron reduction of metal ions such as chromium(VI) and vanadium(V). During the enzymatic reduction process, molecular oxygen is reduced to H2O2, which reacts with the reduced metal complexes to generate hydroxyl radicals. Since the hydroxyl radicals have been suggested to play an important role in Cr(VI) toxicity, this study provides a basis for a recent observation that Cr(VI) mutagenesis is strongly oxygen dependent. These results also point to an enzymatic pathway for the metabolism of some metal ions and concomitant generation of hydroxyl radicals."
1290137,Snow and  Xu 1991,Chromium(III) bound to DNA templates promotes increased polymerase processivity and decreased fidelity during replication in vitro,"Carcinogenic chromium [Cr(VI)] compounds are reduced intracellularly to DNA- and protein-reactive chromium(III) species. However, the role of Cr(III) ions in chromium-induced genotoxicity remains unclear. We have investigated the effects of chromium(III) binding on DNA replication and polymerase processivity in vitro. Chromium ions bind slowly and in a dose-dependent manner to DNA. Micromolar concentrations of free chromium inhibit DNA replication, but if the unbound chromium is removed by gel filtration, the rate of DNA replication by polymerase I (Klenow fragment) on the chromium-bound template is increased greater than 6-fold relative to the control. This increase is paralleled by as much as a 4-fold increase in processivity and a 2-fold decrease in replication fidelity. These effects are optimum when very low concentrations of chromium ions are bound to the DNA [3-4 Cr(III) ions per 1000 nucleotide phosphates]. Increased concentrations of chromium lead to the production of DNA-DNA cross-links and inhibition of polymerase activity. These results suggest that low levels of DNA-bound chromium(III) ions may contribute to chromium mutagenesis and carcinogenesis by altering the kinetics and fidelity of DNA replication.","Chromium(III) bound to DNA templates promotes increased polymerase processivity and decreased fidelity during replication in vitro Abs: Carcinogenic chromium [Cr(VI)] compounds are reduced intracellularly to DNA- and protein-reactive chromium(III) species. However, the role of Cr(III) ions in chromium-induced genotoxicity remains unclear. We have investigated the effects of chromium(III) binding on DNA replication and polymerase processivity in vitro. Chromium ions bind slowly and in a dose-dependent manner to DNA. Micromolar concentrations of free chromium inhibit DNA replication, but if the unbound chromium is removed by gel filtration, the rate of DNA replication by polymerase I (Klenow fragment) on the chromium-bound template is increased greater than 6-fold relative to the control. This increase is paralleled by as much as a 4-fold increase in processivity and a 2-fold decrease in replication fidelity. These effects are optimum when very low concentrations of chromium ions are bound to the DNA [3-4 Cr(III) ions per 1000 nucleotide phosphates]. Increased concentrations of chromium lead to the production of DNA-DNA cross-links and inhibition of polymerase activity. These results suggest that low levels of DNA-bound chromium(III) ions may contribute to chromium mutagenesis and carcinogenesis by altering the kinetics and fidelity of DNA replication."
1290136,Sugiyama 1991,Effects of vitamins on chromium(VI)-induced damage,"The effects of vitamin E and vitamin B2 on DNA damage and cellular reduction of chromium(VI) were investigated using Chinese hamster V-79 cells. Pretreatment with alpha-tocopherol succinate (vitamin E) resulted in a decrease of DNA single-strand breaks produced by Na2CrO4, while similar treatment with riboflavin (vitamin B2) enhanced levels of DNA breaks. In contrast, levels of DNA-protein crosslinks induced by Na2CrO4 were unaffected by these vitamins. Electron spin resonance (ESR) studies showed that incubation of cells with Na2CrO4 resulted in the formation of both chromium(V) and chromium(III) complexes, and cellular pretreatment with vitamin E reduced the level of the chromium(V) complex, whereas pretreatment with vitamin B2 enhanced the level of this intermediate. However, the levels of chromium(III) were unchanged by these vitamins. The uptake of chromate was not affected by vitamin E or vitamin B2, nor were the levels of glutathione or glutathione reductase activity, which are both capable of reducing chromate. ESR studies demonstrated that a chromium(V) species was formed by the reaction of Na2CrO4 with vitamin B2 and that vitamin B2 enhanced the formation of hydroxyl radicals during the reaction of Na2CrO4 and hydrogen peroxide. Treatment cells with Na2CrO4 resulted in a decrease of glutathione reductase activity, and pretreatment with vitamin E restored the enzyme activity suppressed by this metal. However, pretreatment with vitamin B2 enhanced the inhibition of this enzyme by Na2CrO4. Using a colony-forming assay, pretreatment with vitamin E dramatically decreased the cytotoxicity of Na2CrO4, while pretreatment with vitamin B2 was found to result in only a decrease of cell lethality of this metal.(ABSTRACT TRUNCATED AT 250 WORDS)","Effects of vitamins on chromium(VI)-induced damage Abs: The effects of vitamin E and vitamin B2 on DNA damage and cellular reduction of chromium(VI) were investigated using Chinese hamster V-79 cells. Pretreatment with alpha-tocopherol succinate (vitamin E) resulted in a decrease of DNA single-strand breaks produced by Na2CrO4, while similar treatment with riboflavin (vitamin B2) enhanced levels of DNA breaks. In contrast, levels of DNA-protein crosslinks induced by Na2CrO4 were unaffected by these vitamins. Electron spin resonance (ESR) studies showed that incubation of cells with Na2CrO4 resulted in the formation of both chromium(V) and chromium(III) complexes, and cellular pretreatment with vitamin E reduced the level of the chromium(V) complex, whereas pretreatment with vitamin B2 enhanced the level of this intermediate. However, the levels of chromium(III) were unchanged by these vitamins. The uptake of chromate was not affected by vitamin E or vitamin B2, nor were the levels of glutathione or glutathione reductase activity, which are both capable of reducing chromate. ESR studies demonstrated that a chromium(V) species was formed by the reaction of Na2CrO4 with vitamin B2 and that vitamin B2 enhanced the formation of hydroxyl radicals during the reaction of Na2CrO4 and hydrogen peroxide. Treatment cells with Na2CrO4 resulted in a decrease of glutathione reductase activity, and pretreatment with vitamin E restored the enzyme activity suppressed by this metal. However, pretreatment with vitamin B2 enhanced the inhibition of this enzyme by Na2CrO4. Using a colony-forming assay, pretreatment with vitamin E dramatically decreased the cytotoxicity of Na2CrO4, while pretreatment with vitamin B2 was found to result in only a decrease of cell lethality of this metal.(ABSTRACT TRUNCATED AT 250 WORDS)"
1290135,Mikalsen et al. 1991,Reductive metabolism and protein binding of chromium(VI) by P450 protein enzymes,"The cytochrome P450-dependent reduction of Cr(VI) using reconstituted phospholipid vesicles containing purified preparation of various forms of rabbit and rat liver microsomal cytochrome P450 has been investigated. The alcohol-induced form of the rat, P450IIE1, was the most efficient enzyme, 7.2 +/- 0.40 nmol Cr/nmol P450/min, whereas the corresponding rates for rat P450IA1, rat IIB1, rabbit IIB4, rabbit IA2 and rabbit IIE1 were 1.7 +/- 0.09, 2.5 +/- 0.08, 1.6 +/- 0.08, 2.5 +/- 0.15 and 1.6 +/- 0.08 nmol Cr/nmol P450/min respectively. NADPH-cytochrome P450 reductase had Cr(VI) reductase activity which was dependent on enzyme concentration. Below 0.15 nmol P450 reductase/ml the sp. act. was low and constant, while at a higher concentration the activity was markedly dependent upon the amount of enzyme present. In a quantitative binding assay it was shown that binding of [51Cr]Cr(VI) to the catalytic enzymes was proportional to the enzyme concentration up to 0.8 nmol P450/ml, which caused binding of 70% of the total radioactivity. Analysis by SDS-PAGE and autoradiography exhibited binding to the individual catalytic proteins of [51Cr]Cr. EDTA treatment removed the radioactivity from the bands matching P450 and P450 reductase, indicating that Cr(III) is bound to the proteins. The reducing activity of both P450 and P450 reductase was potently inhibited by oxygen. The inhibitory effect of oxygen is not due to reoxidation of the reduced Cr and redox cycling. Rat P450IA1 ethoxycoumarin O deethylase activity was inhibited after preincubation with chromate (CrO4(2-). The P450 reductase inhibitor 2'-AMP stimulated the anaerobic P450 reductase dependent Cr(VI) reductase rate approximately 2-fold. Both CO and CCl4 inhibited the different P450 enzymes to various extents. With rabbit P450IIE1 CCl4 stimulated the Cr(VI) reduction approximately 4-fold, whereas the activity of the other enzymes was inhibited when the reconstituted system was incubated with CrO4(2-) and CCl4 prior to NADPH addition. Neither CO nor CCl4 affected the Cr(VI) reducing activity of the P450 reductase. The difference in CrO4(2-) reducing activity of the P450 enzymes and binding to the enzymes may be important for in vivo endoplasmic catalytic metabolism of CrO4(2-).","Reductive metabolism and protein binding of chromium(VI) by P450 protein enzymes Abs: The cytochrome P450-dependent reduction of Cr(VI) using reconstituted phospholipid vesicles containing purified preparation of various forms of rabbit and rat liver microsomal cytochrome P450 has been investigated. The alcohol-induced form of the rat, P450IIE1, was the most efficient enzyme, 7.2 +/- 0.40 nmol Cr/nmol P450/min, whereas the corresponding rates for rat P450IA1, rat IIB1, rabbit IIB4, rabbit IA2 and rabbit IIE1 were 1.7 +/- 0.09, 2.5 +/- 0.08, 1.6 +/- 0.08, 2.5 +/- 0.15 and 1.6 +/- 0.08 nmol Cr/nmol P450/min respectively. NADPH-cytochrome P450 reductase had Cr(VI) reductase activity which was dependent on enzyme concentration. Below 0.15 nmol P450 reductase/ml the sp. act. was low and constant, while at a higher concentration the activity was markedly dependent upon the amount of enzyme present. In a quantitative binding assay it was shown that binding of [51Cr]Cr(VI) to the catalytic enzymes was proportional to the enzyme concentration up to 0.8 nmol P450/ml, which caused binding of 70% of the total radioactivity. Analysis by SDS-PAGE and autoradiography exhibited binding to the individual catalytic proteins of [51Cr]Cr. EDTA treatment removed the radioactivity from the bands matching P450 and P450 reductase, indicating that Cr(III) is bound to the proteins. The reducing activity of both P450 and P450 reductase was potently inhibited by oxygen. The inhibitory effect of oxygen is not due to reoxidation of the reduced Cr and redox cycling. Rat P450IA1 ethoxycoumarin O deethylase activity was inhibited after preincubation with chromate (CrO4(2-). The P450 reductase inhibitor 2'-AMP stimulated the anaerobic P450 reductase dependent Cr(VI) reductase rate approximately 2-fold. Both CO and CCl4 inhibited the different P450 enzymes to various extents. With rabbit P450IIE1 CCl4 stimulated the Cr(VI) reduction approximately 4-fold, whereas the activity of the other enzymes was inhibited when the reconstituted system was incubated with CrO4(2-) and CCl4 prior to NADPH addition. Neither CO nor CCl4 affected the Cr(VI) reducing activity of the P450 reductase. The difference in CrO4(2-) reducing activity of the P450 enzymes and binding to the enzymes may be important for in vivo endoplasmic catalytic metabolism of CrO4(2-)."
1290134,Borges and  Wetterhahn 1991,Chromium bound to DNA alters cleavage by restriction endonucleases,,Chromium bound to DNA alters cleavage by restriction endonucleases Abs: 
1290133,Tezuka et al. 1991,Protective effect of chromium(III) on acute lethal toxicity of carbon tetrachloride in rats and mice,"Trivalent chromium (Cr(III)) preadministered intraperitoneally (5 mg Cr/kg body weight) to rats and mice protected these animals from acute lethal toxicity of carbon tetrachloride (CCl4). Some other metals, Cr(VI), Cu(II), and Zn(II), had no effect on CCl4 lethal toxicity. DL-alpha-tocopherol, one of the antioxidative agents, showed similar protective effects to Cr(III). Activities of serum GOT and GPT in mice were increased sharply by the administration of CCl4, but these elevations were depressed by Cr(III) preadministration. Serum glucose levels of mice increased transiently after CCl4 administration and then in the control group fell to hypoglycemic levels after 6 hr, whereas the Cr(III)-pretreated group kept to homeostatic levels. Lipid peroxidation of microsomes in mice 24 hr after Cr(III) administration was lower than that of the control. These results suggest that Cr(III) preadministered to mice might act as a radical scavenger to CCl4 to form trichloromethyl radicals which are a major initial product of CCl4 in liver cells.","Protective effect of chromium(III) on acute lethal toxicity of carbon tetrachloride in rats and mice Abs: Trivalent chromium (Cr(III)) preadministered intraperitoneally (5 mg Cr/kg body weight) to rats and mice protected these animals from acute lethal toxicity of carbon tetrachloride (CCl4). Some other metals, Cr(VI), Cu(II), and Zn(II), had no effect on CCl4 lethal toxicity. DL-alpha-tocopherol, one of the antioxidative agents, showed similar protective effects to Cr(III). Activities of serum GOT and GPT in mice were increased sharply by the administration of CCl4, but these elevations were depressed by Cr(III) preadministration. Serum glucose levels of mice increased transiently after CCl4 administration and then in the control group fell to hypoglycemic levels after 6 hr, whereas the Cr(III)-pretreated group kept to homeostatic levels. Lipid peroxidation of microsomes in mice 24 hr after Cr(III) administration was lower than that of the control. These results suggest that Cr(III) preadministered to mice might act as a radical scavenger to CCl4 to form trichloromethyl radicals which are a major initial product of CCl4 in liver cells."
1290132,Capellmann and  Bolt 1992,Chromium (VI) reducing capacity of ascorbic acid and of human plasma in vitro,"In the metabolism of chromium(VI) its reduction in human plasma is of importance; an extracellular reduction of Cr(VI) is regarded as a detoxification step. Ascorbic acid has been suggested to represent the majority of the Cr(VI)-reducing capacity of human plasma. Therefore the kinetics of the reaction of Cr(VI) with ascorbic acid, at biologically realistic concentrations were studied. Ascorbic acid, in 0.2 M HEPES buffer and at concentrations ranging from 14.2 to 113.6 nmol ml-1 (2.5-20.0 microgram ml-1), was mixed with Cr(VI) (0.4-1.5 nmol ml-1) and incubated at pH 7.4 and 37 degrees C. In addition, chromate solutions at different concentrations [1.5-100 nmol ml-1 Cr(VI)], were incubated at 37 degrees C with freshly drawn blood. From these incubates, ascorbic acid and its oxidized form, dehydroascorbic acid, were simultaneously analyzed by HPLC and post-column derivatization. Chromate was determined by flow injection analysis. The reaction kinetics of ascorbic acid in HEPES buffer with Cr(VI) is of pseudo-first order at higher concentrations, whilst apparently at lower concentrations kinetics are consistent with an autocatalyzed reaction. Results obtained after spiking human plasma are similar. However, when Cr(VI) was reacted with human plasma, no changes in the intrinsic contents of ascorbic acid of the plasma samples occurred. Also, comparing different plasma samples the intrinsic plasma contents of ascorbic acid and the reduction capacities for Cr(VI) [ranging between 0.48 and 0.63 nmol ml-1 Cr(VI) to be reduced] did not correlate. This shows that the reduction of Cr(VI) in native human plasma is complex and is not only determined by the plasma ascorbic acid levels. This is in contrast to the situation in lung lavage fluids (Suzuki 1988; Suzuki and Fukuda 1990) where the concentrations of ascorbic acid are much higher than in blood.","Chromium (VI) reducing capacity of ascorbic acid and of human plasma in vitro Abs: In the metabolism of chromium(VI) its reduction in human plasma is of importance; an extracellular reduction of Cr(VI) is regarded as a detoxification step. Ascorbic acid has been suggested to represent the majority of the Cr(VI)-reducing capacity of human plasma. Therefore the kinetics of the reaction of Cr(VI) with ascorbic acid, at biologically realistic concentrations were studied. Ascorbic acid, in 0.2 M HEPES buffer and at concentrations ranging from 14.2 to 113.6 nmol ml-1 (2.5-20.0 microgram ml-1), was mixed with Cr(VI) (0.4-1.5 nmol ml-1) and incubated at pH 7.4 and 37 degrees C. In addition, chromate solutions at different concentrations [1.5-100 nmol ml-1 Cr(VI)], were incubated at 37 degrees C with freshly drawn blood. From these incubates, ascorbic acid and its oxidized form, dehydroascorbic acid, were simultaneously analyzed by HPLC and post-column derivatization. Chromate was determined by flow injection analysis. The reaction kinetics of ascorbic acid in HEPES buffer with Cr(VI) is of pseudo-first order at higher concentrations, whilst apparently at lower concentrations kinetics are consistent with an autocatalyzed reaction. Results obtained after spiking human plasma are similar. However, when Cr(VI) was reacted with human plasma, no changes in the intrinsic contents of ascorbic acid of the plasma samples occurred. Also, comparing different plasma samples the intrinsic plasma contents of ascorbic acid and the reduction capacities for Cr(VI) [ranging between 0.48 and 0.63 nmol ml-1 Cr(VI) to be reduced] did not correlate. This shows that the reduction of Cr(VI) in native human plasma is complex and is not only determined by the plasma ascorbic acid levels. This is in contrast to the situation in lung lavage fluids (Suzuki 1988; Suzuki and Fukuda 1990) where the concentrations of ascorbic acid are much higher than in blood."
1290131,Coudray et al. 1992,Hydroxyl radical formation and lipid peroxidation enhancement by chromium. In vitro study,"Chromium VI compounds have been shown to be carcinogenic in occupationally exposed humans, and to be genotoxic, mutagenic, and carcinogenic in a variety of experimental systems. In contrast, most chromium III compounds are relatively nontoxic, noncarcinogenic, and nonmutagenic. Reduction of Cr6+ leads to reactive intermediates, such as Cr5+, Cr4+, or other radical species. The molecular mechanism for the intracellular Cr6+ reduction has been the focus of recent studies, but the details are still not understood. Our study was initiated to compare the effect of Cr(6+)-hydroxyl radical formation and Cr(6+)-induced lipid peroxidation vs those of Cr3+. Electron spin resonance measurements provide evidence for the formation of long-lived Cr5+ intermediates in the reduction of Cr6+ by glutathione reductase in the presence of NADPH and for the hydroxyl radical formation during the glutathione reductase catalyzed reduction of Cr6+. Hydrogen peroxide suppresses Cr5+ and enhances the formation of hydroxyl radical. Thus, Cr5+ intermediates catalyze generation of hydroxyl radicals from hydrogen peroxide through a Fenton-like reaction. Comparative effects of Cr6+ and Cr3+ on the development of lipid peroxidation were studied by using rat heart homogenate. Heart homogenate was incubated with different concentrations of Cr6+ compounds at 22 degrees C for 60 min. Lipid peroxidation was determined as thiobarbituric acid reacting materiels (TBA-RM). The results confirm that Cr6+ induces lipid peroxidation in the rat heart homogenate. These observations might suggest a possible causative role of lipid peroxidation in Cr6+ toxicity. This enhancement of lipid peroxidation is modified by the addition of some metal chelators and antioxidants. Thus, strategies for combating Cr6+ toxicity should take into account the role of the hydroxy radicals, and hence, steps for blocking its chain propagation and preventing the formation of lipid peroxides.","Hydroxyl radical formation and lipid peroxidation enhancement by chromium. In vitro study Abs: Chromium VI compounds have been shown to be carcinogenic in occupationally exposed humans, and to be genotoxic, mutagenic, and carcinogenic in a variety of experimental systems. In contrast, most chromium III compounds are relatively nontoxic, noncarcinogenic, and nonmutagenic. Reduction of Cr6+ leads to reactive intermediates, such as Cr5+, Cr4+, or other radical species. The molecular mechanism for the intracellular Cr6+ reduction has been the focus of recent studies, but the details are still not understood. Our study was initiated to compare the effect of Cr(6+)-hydroxyl radical formation and Cr(6+)-induced lipid peroxidation vs those of Cr3+. Electron spin resonance measurements provide evidence for the formation of long-lived Cr5+ intermediates in the reduction of Cr6+ by glutathione reductase in the presence of NADPH and for the hydroxyl radical formation during the glutathione reductase catalyzed reduction of Cr6+. Hydrogen peroxide suppresses Cr5+ and enhances the formation of hydroxyl radical. Thus, Cr5+ intermediates catalyze generation of hydroxyl radicals from hydrogen peroxide through a Fenton-like reaction. Comparative effects of Cr6+ and Cr3+ on the development of lipid peroxidation were studied by using rat heart homogenate. Heart homogenate was incubated with different concentrations of Cr6+ compounds at 22 degrees C for 60 min. Lipid peroxidation was determined as thiobarbituric acid reacting materiels (TBA-RM). The results confirm that Cr6+ induces lipid peroxidation in the rat heart homogenate. These observations might suggest a possible causative role of lipid peroxidation in Cr6+ toxicity. This enhancement of lipid peroxidation is modified by the addition of some metal chelators and antioxidants. Thus, strategies for combating Cr6+ toxicity should take into account the role of the hydroxy radicals, and hence, steps for blocking its chain propagation and preventing the formation of lipid peroxides."
1290130,Faux et al. 1992,Production of 8-hydroxydeoxyguanosine in isolated DNA by chromium(VI) and chromium(V),"Chromium(VI) and Cr(V) compounds increased the concentration of 8-hydroxydeoxyguanosine (oh8dG) in isolated DNA, whereas no such increase was seen with Cr(III). Furthermore, incubating DNA with H2O2 and Cr(VI) or Cr(V) potentiated the formation of oh8dG above levels observed with either chromium compound alone. In the presence of catalase, the increase in DNA oxidation observed with Cr(VI) was inhibited, the base oxidation observed being equivalent to background levels, and this indicated involvement of H2O2 in the mechanism. Glutathione did not enhance chromium-induced formation of this oxidized base. These results help to explain a mechanism of chromium-induced DNA oxidation involving H2O2 via a Fenton-type reaction.","Production of 8-hydroxydeoxyguanosine in isolated DNA by chromium(VI) and chromium(V) Abs: Chromium(VI) and Cr(V) compounds increased the concentration of 8-hydroxydeoxyguanosine (oh8dG) in isolated DNA, whereas no such increase was seen with Cr(III). Furthermore, incubating DNA with H2O2 and Cr(VI) or Cr(V) potentiated the formation of oh8dG above levels observed with either chromium compound alone. In the presence of catalase, the increase in DNA oxidation observed with Cr(VI) was inhibited, the base oxidation observed being equivalent to background levels, and this indicated involvement of H2O2 in the mechanism. Glutathione did not enhance chromium-induced formation of this oxidized base. These results help to explain a mechanism of chromium-induced DNA oxidation involving H2O2 via a Fenton-type reaction."
1290129,White et al. 1979,Comparative toxicity studies of chromium-rich welding fumes and chromium on an established human cell line,"HEEP COPYRIGHT: BIOL ABS. Effects of welding fumes in an established human cell line NHIK 3025 were studied. The welding fume material was collected by air filtration from the welding of stainless steel with a stainless-steel electrode. Addition of the fume particles suspended in 0.9% NaCl to the culture medium reduced cell proliferation and substantially increased the fraction of abnormally large cells. A filtrate of this suspension produced similar effects. Analysis showed that hexavalent Cr constituted 3.5% of the total welding fume material collected. Other metals such as Ni, Fe, Mn were tested at their concentrations in the welding fume particles but displayed only slight toxicity. Corresponding concentrations of hexavalent Cr alone produced very similar effects of those of the welding fume suspension and filtrate. The toxic effect of the welding fume sample on the bioassay system employed is almost entirely due to hexavalent Cr.","Comparative toxicity studies of chromium-rich welding fumes and chromium on an established human cell line Abs: HEEP COPYRIGHT: BIOL ABS. Effects of welding fumes in an established human cell line NHIK 3025 were studied. The welding fume material was collected by air filtration from the welding of stainless steel with a stainless-steel electrode. Addition of the fume particles suspended in 0.9% NaCl to the culture medium reduced cell proliferation and substantially increased the fraction of abnormally large cells. A filtrate of this suspension produced similar effects. Analysis showed that hexavalent Cr constituted 3.5% of the total welding fume material collected. Other metals such as Ni, Fe, Mn were tested at their concentrations in the welding fume particles but displayed only slight toxicity. Corresponding concentrations of hexavalent Cr alone produced very similar effects of those of the welding fume suspension and filtrate. The toxic effect of the welding fume sample on the bioassay system employed is almost entirely due to hexavalent Cr."
1290122,Deschamps et al. 1992,Cohort Mortality Study of Workers Exposed to Chromate and Tobacco,"A study of lung cancer mortality in chromate pigment workers was conducted. The cohort consisted of 297 males employed at a French pigment production factory between January 1, 1958 and December 31, 1987 who had been exposed to lead-chromate (7758976), zinc-chromate (13530659), strontium-chromate (7789062), or barium-chromate (10294403). The vital status of the cohort was determined through 1987. Causes of death were determined from death certificates and interviews with the doctors who signed the death certificates. Standardized mortality ratios (SMRs) were computed using mortality rates for the general male population in the region where the factory was located as the reference. Mortality data on lung cancer were presented. Attempts were made to examine the role of smoking in the lung cancer mortality. Industrial hygiene monitoring for airborne chromates was performed. All workers had been exposed to airborne chromate concentrations above the occupational standard, 50 micrograms per cubic meter, 33% of the time. Ninety seven deaths, versus 92.66 expected, occurred in the cohort during the study period; cause of death information was available for 92. There were 18 deaths from lung cancer versus 5.62 expected. This yielded an SMR of 3.2, which represented a significantly increased risk. When analyzed by period of employment, lung cancer mortality occurring from 1969 to the end of the study was significantly elevated. The duration of chromate exposure for the workers who died from lung cancer varied from 1.5 to 29.6 years. Sixteen of the workers who died from lung cancer were smokers; however, the smoking habits of the cohort were not known. The authors conclude that this population of chromate exposed workers is at high risk for lung cancer. The excess risk is not due to smoking.","Cohort Mortality Study of Workers Exposed to Chromate and Tobacco Abs: A study of lung cancer mortality in chromate pigment workers was conducted. The cohort consisted of 297 males employed at a French pigment production factory between January 1, 1958 and December 31, 1987 who had been exposed to lead-chromate (7758976), zinc-chromate (13530659), strontium-chromate (7789062), or barium-chromate (10294403). The vital status of the cohort was determined through 1987. Causes of death were determined from death certificates and interviews with the doctors who signed the death certificates. Standardized mortality ratios (SMRs) were computed using mortality rates for the general male population in the region where the factory was located as the reference. Mortality data on lung cancer were presented. Attempts were made to examine the role of smoking in the lung cancer mortality. Industrial hygiene monitoring for airborne chromates was performed. All workers had been exposed to airborne chromate concentrations above the occupational standard, 50 micrograms per cubic meter, 33% of the time. Ninety seven deaths, versus 92.66 expected, occurred in the cohort during the study period; cause of death information was available for 92. There were 18 deaths from lung cancer versus 5.62 expected. This yielded an SMR of 3.2, which represented a significantly increased risk. When analyzed by period of employment, lung cancer mortality occurring from 1969 to the end of the study was significantly elevated. The duration of chromate exposure for the workers who died from lung cancer varied from 1.5 to 29.6 years. Sixteen of the workers who died from lung cancer were smokers; however, the smoking habits of the cohort were not known. The authors conclude that this population of chromate exposed workers is at high risk for lung cancer. The excess risk is not due to smoking."
1290119,Hernberg 1977,Incidence of Cancer in Population with Exceptional Exposure to Metals,"The experimental and epidemiologic evidence for cancer induction by metals was reviewed. Arsenic (7440382) has not been shown to be carcinogenic in experimental animals. In man, arsenic exposure has been connected with an excess of skin and lung cancer, cancer of the lymphatic system, liver hemangiosarcoma, and lung cancer. Beryllium (7440417) injected intravenously has caused osteogenic sarcomas in rabbits and mice, and inhalation of beryllium aerosols has induced pulmonary cancer in rats and monkeys. The epidemiologic data for carcinogenesis connected with occupational exposure to beryllium has been equivocal. Cadmium (7440439) injected into experimental animals has produced local sarcomas and testicular tumors. Occupational exposure to cadmium may be related to excesses of prostate, kidney, and bronchial cancers. Chromium (7440473), both metallic and as the hexavalent compound, has been conclusively shown to cause cancer in animals when administered by a number of different routes, but there is no evidence for the carcinogenicity of trivalent chromium. In man, occupational exposure to hexavalent chromium compounds has long been connected with respiratory tract cancers. Iron (7439896) as a polysaccharide complex, when administered parenterally in high doses, has induced local sarcomas in mice, rats, and rabbits. There is epidemiologic evidence for increased lung cancer among hematite miners, but the role of iron is not clear because of concurrent exposure to radon daughters. Nickel (7440020) has caused sarcomas and carcinomas in rodents. Lung cancer and cancer of the nasal sinuses have been found in excess among nickel refinery workers. The effect has declined with time, probably because of improved work conditions. No metals other than those discussed have produced epidemiologic evidence for a carcinogenic effect. In particular, lead (7439921) has been the subject of three mortality studies, but no excess of cancer has been detected.","Incidence of Cancer in Population with Exceptional Exposure to Metals Abs: The experimental and epidemiologic evidence for cancer induction by metals was reviewed. Arsenic (7440382) has not been shown to be carcinogenic in experimental animals. In man, arsenic exposure has been connected with an excess of skin and lung cancer, cancer of the lymphatic system, liver hemangiosarcoma, and lung cancer. Beryllium (7440417) injected intravenously has caused osteogenic sarcomas in rabbits and mice, and inhalation of beryllium aerosols has induced pulmonary cancer in rats and monkeys. The epidemiologic data for carcinogenesis connected with occupational exposure to beryllium has been equivocal. Cadmium (7440439) injected into experimental animals has produced local sarcomas and testicular tumors. Occupational exposure to cadmium may be related to excesses of prostate, kidney, and bronchial cancers. Chromium (7440473), both metallic and as the hexavalent compound, has been conclusively shown to cause cancer in animals when administered by a number of different routes, but there is no evidence for the carcinogenicity of trivalent chromium. In man, occupational exposure to hexavalent chromium compounds has long been connected with respiratory tract cancers. Iron (7439896) as a polysaccharide complex, when administered parenterally in high doses, has induced local sarcomas in mice, rats, and rabbits. There is epidemiologic evidence for increased lung cancer among hematite miners, but the role of iron is not clear because of concurrent exposure to radon daughters. Nickel (7440020) has caused sarcomas and carcinomas in rodents. Lung cancer and cancer of the nasal sinuses have been found in excess among nickel refinery workers. The effect has declined with time, probably because of improved work conditions. No metals other than those discussed have produced epidemiologic evidence for a carcinogenic effect. In particular, lead (7439921) has been the subject of three mortality studies, but no excess of cancer has been detected."
1290115,Ulmeanu et al. 1997,Acute poisoning with hexavalent chromium in a child,Biosis copyright: biol abs. rrm meeting abstract meeting poster human child hexavalent chromium toxin toxicology gastrointestinal toxicity circulatory insufficiency coma acute renal failure acute hepatic failure digestive system disease toxicity vascular disease nervous system disease urologic disease,Acute poisoning with hexavalent chromium in a child Abs: Biosis copyright: biol abs. rrm meeting abstract meeting poster human child hexavalent chromium toxin toxicology gastrointestinal toxicity circulatory insufficiency coma acute renal failure acute hepatic failure digestive system disease toxicity vascular disease nervous system disease urologic disease
1290111,Osadchiy et al. 1993,Decrease in the hormonal function of the placenta in pregnant women coming in contact with hexavalent chromium compounds,Biosis copyright: biol abs. rrm meeting abstract reproductive toxicology radioimmunoassay worker exposure,Decrease in the hormonal function of the placenta in pregnant women coming in contact with hexavalent chromium compounds Abs: Biosis copyright: biol abs. rrm meeting abstract reproductive toxicology radioimmunoassay worker exposure
1290107,NJ DHSS 2010,"Health consultation: Analysis of oral, esophageal and stomach cancer incidence near chromium-contaminated sites in Jersey City (a/k/a Hudson County Chromium Sites) Jersey City, Hudson County, New Jersey","Prepared in cooperation with New Jersey Dept. of Environmental Protection, Trenton. Sponsored by Agency for Toxic Substances and Disease Registry, Atlanta, GA. Div. of Health Assessment and Consultation. on community concerns, the New Jersey Department of Health and Senior Services (NJDHSS) and the New Jersey Department of Environmental Protection (NJDEP) released a Health Consultation in October 2008 that analyzed the relationship between historic exposure to chromium from chromium ore processing residue (COPR) sites and the incidence of lung cancer in Jersey City, Hudson County, NJ. COPR is known to contain hexavalent chromium, a known human lung carcinogen. One of the recommendations in that 2008 Health Consultation was to replicate the analysis for other cancers potentially related to chromium exposure.","Health consultation: Analysis of oral, esophageal and stomach cancer incidence near chromium-contaminated sites in Jersey City (a/k/a Hudson County Chromium Sites) Jersey City, Hudson County, New Jersey Abs: Prepared in cooperation with New Jersey Dept. of Environmental Protection, Trenton. Sponsored by Agency for Toxic Substances and Disease Registry, Atlanta, GA. Div. of Health Assessment and Consultation. on community concerns, the New Jersey Department of Health and Senior Services (NJDHSS) and the New Jersey Department of Environmental Protection (NJDEP) released a Health Consultation in October 2008 that analyzed the relationship between historic exposure to chromium from chromium ore processing residue (COPR) sites and the incidence of lung cancer in Jersey City, Hudson County, NJ. COPR is known to contain hexavalent chromium, a known human lung carcinogen. One of the recommendations in that 2008 Health Consultation was to replicate the analysis for other cancers potentially related to chromium exposure."
1290106,NJ DEP 2008,"Health Consultation: Analysis of Lung Cancer Incidence near Chromium-Contaminated Sites in New Jersey (a/k/a Hudson County Chromium Sites) Jersey City, Hudson County, New Jersey","Prepared in cooperation with New Jersey Dept. of Environmental Protection, Trenton. Office of Science and Research. Sponsored by Agency for Toxic Substances and Disease Registry, Atlanta, GA. Div. of Health Assessment and Consultation. ponse to community requests, the New Jersey Department of Environmental Protection (NJDEP) and the New Jersey Department of Health and Senior Services (NJDHSS) evaluated the relationship between historic exposure to chromium from chromium ore processing residue (COPR) sites and the incidence of lung cancer in Jersey City (Hudson County), New Jersey over a 25 year period. Hudson County was a major center for chromium ore processing and manufacturing. Nearly three million tons of COPR was produced, and much of was used as fill material in construction of residential and commercial sites in the 1950s and 1960s. More than 160 COPR disposal sites have been identified in Hudson County, 136 sites in Jersey City alone. COPR contained high concentrations of total chromium, with small and varying proportions being hexavalent chromium (Cr+6), the most toxic form. Cr+6 is known to cause lung cancer in humans. This investigation of lung cancer incidence included the population residing in Jersey City from 1979 through 2003. Annual population estimates were derived from U.S. Census Bureau data. The New Jersey State Cancer Registry in the NJDHSS was used to determine the number of lung cancer cases occurring in the Jersey City population. A total of 3,249 malignant incident lung cancer cases (2,040 males and 1,209 females) were included in this investigation. Lung cancer cases were aggregated by U.S. Census Bureau census block groups, based on the cases residence at the time of diagnosis.","Health Consultation: Analysis of Lung Cancer Incidence near Chromium-Contaminated Sites in New Jersey (a/k/a Hudson County Chromium Sites) Jersey City, Hudson County, New Jersey Abs: Prepared in cooperation with New Jersey Dept. of Environmental Protection, Trenton. Office of Science and Research. Sponsored by Agency for Toxic Substances and Disease Registry, Atlanta, GA. Div. of Health Assessment and Consultation. ponse to community requests, the New Jersey Department of Environmental Protection (NJDEP) and the New Jersey Department of Health and Senior Services (NJDHSS) evaluated the relationship between historic exposure to chromium from chromium ore processing residue (COPR) sites and the incidence of lung cancer in Jersey City (Hudson County), New Jersey over a 25 year period. Hudson County was a major center for chromium ore processing and manufacturing. Nearly three million tons of COPR was produced, and much of was used as fill material in construction of residential and commercial sites in the 1950s and 1960s. More than 160 COPR disposal sites have been identified in Hudson County, 136 sites in Jersey City alone. COPR contained high concentrations of total chromium, with small and varying proportions being hexavalent chromium (Cr+6), the most toxic form. Cr+6 is known to cause lung cancer in humans. This investigation of lung cancer incidence included the population residing in Jersey City from 1979 through 2003. Annual population estimates were derived from U.S. Census Bureau data. The New Jersey State Cancer Registry in the NJDHSS was used to determine the number of lung cancer cases occurring in the Jersey City population. A total of 3,249 malignant incident lung cancer cases (2,040 males and 1,209 females) were included in this investigation. Lung cancer cases were aggregated by U.S. Census Bureau census block groups, based on the cases residence at the time of diagnosis."
1290102,Ernst 1994,Reproductive toxicological aspects of chromium in males,Thesis (ph.d.). and our present understanding of the effects of chromium on male fertility a number of studies were designed to achieve this through the use of chromium intoxicated experimental animals and through investigation of sexual hormones and sperm quality in welders. Also in view of the lack of an experimental model for effects of noxious substance on the epididymal spermatozoa the main objectives of the series of studies reviewed here were: A. To establish a model for evaluation of epididymal sperm count and motility in the rat. B. To investigate and compare the effects of tri- and hexavalent chromium on epididymal spermatozoa. Further to describe the effects of low-dose long-time exposure of rats to the most toxicological interesting chromium oxidative state - hexavalent chromium. C. By the use of autoradiography and (gamma)-countinuing to expand the present knowledge on the distribution of chromium in the body with special reference to the male reproductive organs. D. To describe the effects of exposure to hexavalent chromium in welding fume on levels of sexual hormones and semen parameters in welders. (EG). (Atomindex citation 27:007880),Reproductive toxicological aspects of chromium in males Abs: Thesis (ph.d.). and our present understanding of the effects of chromium on male fertility a number of studies were designed to achieve this through the use of chromium intoxicated experimental animals and through investigation of sexual hormones and sperm quality in welders. Also in view of the lack of an experimental model for effects of noxious substance on the epididymal spermatozoa the main objectives of the series of studies reviewed here were: A. To establish a model for evaluation of epididymal sperm count and motility in the rat. B. To investigate and compare the effects of tri- and hexavalent chromium on epididymal spermatozoa. Further to describe the effects of low-dose long-time exposure of rats to the most toxicological interesting chromium oxidative state - hexavalent chromium. C. By the use of autoradiography and (gamma)-countinuing to expand the present knowledge on the distribution of chromium in the body with special reference to the male reproductive organs. D. To describe the effects of exposure to hexavalent chromium in welding fume on levels of sexual hormones and semen parameters in welders. (EG). (Atomindex citation 27:007880)
1290099,Deng et al. 1990,An outbreak of chromium ulcer in a manufacturing plant,"On May 23, 1989, managers of a manufacturing plant requested an investigation of an outbreak of hand ulceration and skin discoloration among workers. The plant has manufactured kitchen ranges for 30 years and employs approximately 633 hourly workers. The affected employees worked in the enamel department, where metallic range tops are coated with a &quot;ground coat&quot; or sprayed with an enamel coloring, and then baked in ovens at 1200F. Our evaluation included physical examinations, environmental sampling, and a questionnaire eliciting information concerning skin ulceration job history, demographics, and use of protective practices. We identified 10 enamel department workers (13.5%) who developed chromium ulcers between January 1st and June 30th, 1988. Ulcers were found on hands, forearms, periumbilical area and/or axillae. Within the enamel department, workers who handled conveyer hooks used to suspend range tops as they passed through the oven were at greatest risk (rate ratio (RR) = 12.44, 95% confidence interval (CI) = 2.90-53.35). Workers who wore gloves were protected from developing ulcers (RR = 0.08, 95% CI = 0.01-0.60). Normally, trivalent chromium (Cr+3) does not cause skin ulcers unless it is oxidized to hezavalent chromium Cr+6). The enamel used contained only Cr+3, not Cr+6, but analysis of hooks that had passed through the oven revealed Cr+6 on their surface. A mechanical failure of the oven resulted in the formation of sharp edges of the parts and consequently causing the abrasion of exposed skin. We believe Cr+3 was converted to Cr+6 during the baking process which associated with the mechanical failure of the oven causing this outbreak.","An outbreak of chromium ulcer in a manufacturing plant Abs: On May 23, 1989, managers of a manufacturing plant requested an investigation of an outbreak of hand ulceration and skin discoloration among workers. The plant has manufactured kitchen ranges for 30 years and employs approximately 633 hourly workers. The affected employees worked in the enamel department, where metallic range tops are coated with a &quot;ground coat&quot; or sprayed with an enamel coloring, and then baked in ovens at 1200F. Our evaluation included physical examinations, environmental sampling, and a questionnaire eliciting information concerning skin ulceration job history, demographics, and use of protective practices. We identified 10 enamel department workers (13.5%) who developed chromium ulcers between January 1st and June 30th, 1988. Ulcers were found on hands, forearms, periumbilical area and/or axillae. Within the enamel department, workers who handled conveyer hooks used to suspend range tops as they passed through the oven were at greatest risk (rate ratio (RR) = 12.44, 95% confidence interval (CI) = 2.90-53.35). Workers who wore gloves were protected from developing ulcers (RR = 0.08, 95% CI = 0.01-0.60). Normally, trivalent chromium (Cr+3) does not cause skin ulcers unless it is oxidized to hezavalent chromium Cr+6). The enamel used contained only Cr+3, not Cr+6, but analysis of hooks that had passed through the oven revealed Cr+6 on their surface. A mechanical failure of the oven resulted in the formation of sharp edges of the parts and consequently causing the abrasion of exposed skin. We believe Cr+3 was converted to Cr+6 during the baking process which associated with the mechanical failure of the oven causing this outbreak."
1290090,U.S. EPA 2000,USEPA status report: Strontium chromate with cover letter dated 012480,Strontium chromate was tested for carcinogenicity in an implantation study in rats. A summary report of interim results indicates implantation in the bronchiolus of stainless steel mesh containing pellets of strontium chromate suspended in an equal weight of cholesterol led to death at 1 year. Lesions found in the left lung of 21 of the dead animals were reported to be consistent with the appearance of squamous cell carcinomas. No further information was provided regarding experimental protocol or results. The production/importation range was between 123 thousand and 1.2 million pounds in 1977.,USEPA status report: Strontium chromate with cover letter dated 012480 Abs: Strontium chromate was tested for carcinogenicity in an implantation study in rats. A summary report of interim results indicates implantation in the bronchiolus of stainless steel mesh containing pellets of strontium chromate suspended in an equal weight of cholesterol led to death at 1 year. Lesions found in the left lung of 21 of the dead animals were reported to be consistent with the appearance of squamous cell carcinomas. No further information was provided regarding experimental protocol or results. The production/importation range was between 123 thousand and 1.2 million pounds in 1977.
1290088,NTP 1995,Final Report on potassium dichromate (hexavalent): The effects of potassium dichromate on BALB/c mice when administered in the diet: Volume II of II,"See also PB97-125363, Volume 1 of 2. Sponsored by National Toxicology Program, Research Triangle Park, NC. nts: Introduction; Test Article; Experimental Design; Study Design; Assessment of the Results; Storage of Records; Personnel; Subcontractors; Milestone Schedule R.O.W. Sciences 8989-19; Limited Purity and Dose Formulation Report; and Standard Operating Procedures Applicable.","Final Report on potassium dichromate (hexavalent): The effects of potassium dichromate on BALB/c mice when administered in the diet: Volume II of II Abs: See also PB97-125363, Volume 1 of 2. Sponsored by National Toxicology Program, Research Triangle Park, NC. nts: Introduction; Test Article; Experimental Design; Study Design; Assessment of the Results; Storage of Records; Personnel; Subcontractors; Milestone Schedule R.O.W. Sciences 8989-19; Limited Purity and Dose Formulation Report; and Standard Operating Procedures Applicable."
1279971,Kaiser 1980,Correlation and Prediction of Metal Toxicity to Aquatic Biota,"Published data on the toxicity of metal ions to aquatic biota, in particular Daphnia magna, were analyzed for their correlation with ion specific physicochemical parameters. Significant correlations were obtained for three groups of ions with similar electron configurations in the outer orbitals. Group I ions include Na, Be, Ba, Al, and Cr with inert gas-like electron configurations; group II ions include Cr, Mn, Fe, Co, Ni, Cu, Zn , As, Cd, Pt, Au, and Hg with partially or completely filled d electron orbitals; group III ions include Sn, As, Se, and Pb. The toxicity of an ion within a group can be calculated from a general equation. Delta IP. (Deal-EIS)","Correlation and Prediction of Metal Toxicity to Aquatic Biota Abs: Published data on the toxicity of metal ions to aquatic biota, in particular Daphnia magna, were analyzed for their correlation with ion specific physicochemical parameters. Significant correlations were obtained for three groups of ions with similar electron configurations in the outer orbitals. Group I ions include Na, Be, Ba, Al, and Cr with inert gas-like electron configurations; group II ions include Cr, Mn, Fe, Co, Ni, Cu, Zn , As, Cd, Pt, Au, and Hg with partially or completely filled d electron orbitals; group III ions include Sn, As, Se, and Pb. The toxicity of an ion within a group can be calculated from a general equation. Delta IP. (Deal-EIS)"
1276602,Nayan and  Dey 1970,"ACIDITY OF FOLIC ACID FOR CARCINOGENIC METAL IONS, ALUMINIUM(III), CHROMIUM(III), BERYLLIUM(II), LEAD(II) AND URANIUM(VI)",,"ACIDITY OF FOLIC ACID FOR CARCINOGENIC METAL IONS, ALUMINIUM(III), CHROMIUM(III), BERYLLIUM(II), LEAD(II) AND URANIUM(VI) Abs: "
1274934,Crouch 1996,Uncertainty distributions for cancer potency factors: Combining epidemiological studies with laboratory bioassays - The example of acrylonitrile,,Uncertainty distributions for cancer potency factors: Combining epidemiological studies with laboratory bioassays - The example of acrylonitrile Abs: 
1273909,Tabershaw Occupational Medicine Associates 1982,"1979 Cross-sectional health study of the chrome department workers at the Baltimore, Maryland plant of Koppers Company, INC",,"1979 Cross-sectional health study of the chrome department workers at the Baltimore, Maryland plant of Koppers Company, INC Abs: "
1270461,Loeb et al. 1977,INFIDELITY OF DNA SYNTHESIS AS RELATED TO MUTAGENESIS AND CARCINOGENESIS,,INFIDELITY OF DNA SYNTHESIS AS RELATED TO MUTAGENESIS AND CARCINOGENESIS Abs: 
1270016,Abu ZUHRI and  Voelter 1998,"Applications of adsorptive stripping voltammetry for the trace analysis of metals, pharmaceuticals and biomolecules","BIOSIS COPYRIGHT: BIOL ABS. A review with 159 references is presented on the applications of adsorptive stripping voltammetry (AdSV) for determining trace metal ions in different environmental samples (e.g. water, soil, plant, biological fluids). The analytical applications of AdSV to biologically active organic compounds (e.g. pharmaceuticals, pesticides, biomolecules) are also discussed.","Applications of adsorptive stripping voltammetry for the trace analysis of metals, pharmaceuticals and biomolecules Abs: BIOSIS COPYRIGHT: BIOL ABS. A review with 159 references is presented on the applications of adsorptive stripping voltammetry (AdSV) for determining trace metal ions in different environmental samples (e.g. water, soil, plant, biological fluids). The analytical applications of AdSV to biologically active organic compounds (e.g. pharmaceuticals, pesticides, biomolecules) are also discussed."
1269896,Gadd 1993,TANSLEY REVIEW NO. 47 INTERACTIONS OF FUNGI WITH TOXIC METALS,BIOSIS COPYRIGHT: BIOL ABS. RRM REVIEW MACROFUNGI YEASTS MYCORRHIZAL FUNGI PROTEIN PEPTIDES RADIONUCLIDES RESISTANCE TOLERANCE CELL WALL BINDING TRANSPORT RECOVERY BIOSORPTION VACUOLAR COMPARTMENTATION TRANSFORMATION METABOLISM ENVIRONMENTAL INFLUENCES BIOTECHNOLOGY MICROBIAL INDUSTRY POLLUTION WASTE MANAGEMENT,TANSLEY REVIEW NO. 47 INTERACTIONS OF FUNGI WITH TOXIC METALS Abs: BIOSIS COPYRIGHT: BIOL ABS. RRM REVIEW MACROFUNGI YEASTS MYCORRHIZAL FUNGI PROTEIN PEPTIDES RADIONUCLIDES RESISTANCE TOLERANCE CELL WALL BINDING TRANSPORT RECOVERY BIOSORPTION VACUOLAR COMPARTMENTATION TRANSFORMATION METABOLISM ENVIRONMENTAL INFLUENCES BIOTECHNOLOGY MICROBIAL INDUSTRY POLLUTION WASTE MANAGEMENT
1269831,Nies 1999,Microbial heavy-metal resistance,"BIOSIS COPYRIGHT: BIOL ABS. We are just beginning to understand the metabolism of heavy metals and to use their metabolic functions in biotechnology, although heavy metals comprise the major part of the elements in the periodic table. Because they can form complex compounds, some heavy metal ions are essential trace elements, but, essential or not, most heavy metals are toxic at higher concentrations. This review describes the workings of known metal-resistance systems in microorganisms. After an account of the basic princ","Microbial heavy-metal resistance Abs: BIOSIS COPYRIGHT: BIOL ABS. We are just beginning to understand the metabolism of heavy metals and to use their metabolic functions in biotechnology, although heavy metals comprise the major part of the elements in the periodic table. Because they can form complex compounds, some heavy metal ions are essential trace elements, but, essential or not, most heavy metals are toxic at higher concentrations. This review describes the workings of known metal-resistance systems in microorganisms. After an account of the basic princ"
1269825,ANON 1998,"International Symposium on Biosorption and Bioremediation (Prague, Czech Republic; July 12-17, 1998)","BIOSIS COPYRIGHT: BIOL ABS. This meeting contains abstracts of 115 papers, written in English, covering biosorption and bioaccumulation of heavy metals; screening, physiology, and genetics of degrading organisms; biodegradation of persistent organic compounds; and practical use of new bioremediation technologies, dealing with bacteria, fungi, and other microorganisms.","International Symposium on Biosorption and Bioremediation (Prague, Czech Republic; July 12-17, 1998) Abs: BIOSIS COPYRIGHT: BIOL ABS. This meeting contains abstracts of 115 papers, written in English, covering biosorption and bioaccumulation of heavy metals; screening, physiology, and genetics of degrading organisms; biodegradation of persistent organic compounds; and practical use of new bioremediation technologies, dealing with bacteria, fungi, and other microorganisms."
1269633,Fairhall 1936,Toxic Dusts and Fumes,"Types of toxic dusts and fumes, sampling procedures, and methods of analysis are reviewed. Toxic dusts and fumes of outstanding importance are listed as arsenic (7440382), mercury (7439976), lead (7439921), phosphorus (7723140), manganese (7439965), cadmium (7440439), zinc (7440666), hexavalent-chromium (18540299) compounds, fluorides, and silicofluorides, certain dye stuff intermediates, and other organic compounds. The uses of these dusts and fumes and hazards and symptoms of poisoning from these dusts and fumes are discussed. Caustic dusts, tar (8007452) dust, and irritating dusts are so cited as causing problems in industry. The development of new alloys also entails production of dusts and fumes about which little is yet known such as sodium-silico-fluoride (16893859), barium-fluoride (7787328), beryllium-oxide (1304569), and beryllium-fluoride (7787497). Although the most dangerous exposure to these toxic substances occurs among workers, the hazards to the general public from industrial facilities is also noted. Methods of sampling and analysis of these materials are suggested. It is emphasized that the sampling is as important as the analysis. Difficulties encountered by toxicologist in evaluating the toxicity of dusts and fumes due to the rapid increase in number of chemicals and substances generally encountered, and the problems of interpreting data from animal studies in terms of humans are discussed. The author suggests that much research needs to be done on the transport of these toxic substances within the body and their ultimate physiological activity.","Toxic Dusts and Fumes Abs: Types of toxic dusts and fumes, sampling procedures, and methods of analysis are reviewed. Toxic dusts and fumes of outstanding importance are listed as arsenic (7440382), mercury (7439976), lead (7439921), phosphorus (7723140), manganese (7439965), cadmium (7440439), zinc (7440666), hexavalent-chromium (18540299) compounds, fluorides, and silicofluorides, certain dye stuff intermediates, and other organic compounds. The uses of these dusts and fumes and hazards and symptoms of poisoning from these dusts and fumes are discussed. Caustic dusts, tar (8007452) dust, and irritating dusts are so cited as causing problems in industry. The development of new alloys also entails production of dusts and fumes about which little is yet known such as sodium-silico-fluoride (16893859), barium-fluoride (7787328), beryllium-oxide (1304569), and beryllium-fluoride (7787497). Although the most dangerous exposure to these toxic substances occurs among workers, the hazards to the general public from industrial facilities is also noted. Methods of sampling and analysis of these materials are suggested. It is emphasized that the sampling is as important as the analysis. Difficulties encountered by toxicologist in evaluating the toxicity of dusts and fumes due to the rapid increase in number of chemicals and substances generally encountered, and the problems of interpreting data from animal studies in terms of humans are discussed. The author suggests that much research needs to be done on the transport of these toxic substances within the body and their ultimate physiological activity."
1269138,Lauwerys 1989,Metals Epidemiological and Experimental Evidence for Carcinogenicity,"A review was presented on the epidemiological and experimental evidence for the carcinogenicity of the following metals and metalloids, and their compounds: arsenic (7440382), antimony (7440360), beryllium (7440417), cadmium (7440439), chromium (7440473), cobalt (7440484), nickel (7440020), iron (7439896), lead (7439921), and manganese (7439965). Studies have indicated that inorganic arsenic, some hexavalent chromium compounds, certain nickel compounds present in some nickel refineries, beryllium and its salts, cadmium-oxide (1306190) dust and fumes under very high exposure conditions, and antimony-trioxide (1327339) dust at high concentration should be considered capable on inducing human cancer. The possible carcinogenic activity of cobalt toward humans was still uncertain. Iron-oxide, lead, and manganese do not appear to represent a human carcinogenic risk under usual exposure conditions. There was a possibility that iron containing dust may act as a cocarcinogen.","Metals Epidemiological and Experimental Evidence for Carcinogenicity Abs: A review was presented on the epidemiological and experimental evidence for the carcinogenicity of the following metals and metalloids, and their compounds: arsenic (7440382), antimony (7440360), beryllium (7440417), cadmium (7440439), chromium (7440473), cobalt (7440484), nickel (7440020), iron (7439896), lead (7439921), and manganese (7439965). Studies have indicated that inorganic arsenic, some hexavalent chromium compounds, certain nickel compounds present in some nickel refineries, beryllium and its salts, cadmium-oxide (1306190) dust and fumes under very high exposure conditions, and antimony-trioxide (1327339) dust at high concentration should be considered capable on inducing human cancer. The possible carcinogenic activity of cobalt toward humans was still uncertain. Iron-oxide, lead, and manganese do not appear to represent a human carcinogenic risk under usual exposure conditions. There was a possibility that iron containing dust may act as a cocarcinogen."
1268371,Mcgregor 1998,INDUSTRIAL CHEMICALS AND HUMAN CANCER,BIOSIS COPYRIGHT: BIOL ABS. RRM JOURNAL ARTICLE HUMAN WORKER TOXIC CHEMICALS OCCUPATIONAL EXPOSURE CARCINOGEN CARCINOGENESIS TUMOR BIOLOGY TOXICOLOGY CANCER POLLUTION NEOPLASTIC DISEASE RISK FACTORS OCCUPATIONAL DISEASE,INDUSTRIAL CHEMICALS AND HUMAN CANCER Abs: BIOSIS COPYRIGHT: BIOL ABS. RRM JOURNAL ARTICLE HUMAN WORKER TOXIC CHEMICALS OCCUPATIONAL EXPOSURE CARCINOGEN CARCINOGENESIS TUMOR BIOLOGY TOXICOLOGY CANCER POLLUTION NEOPLASTIC DISEASE RISK FACTORS OCCUPATIONAL DISEASE
1268333,Dean et al. 1998,Atomic spectrometry update: Environmental analysis,"BIOSIS COPYRIGHT: BIOL ABS. This is the thirteenth annual review published in JAAS of the applications of atomic spectroscopy to the chemical analysis of environmental samples. The format used continues to be similar to that of previous years, highlighting the main features of this particular subject. Developments in instrumentation are not essentially a feature of this update, and so the emphasis is mainly with the establishment of reliable and robust methods of environmental analysis. The update does, however, focus on the areas of sampling, sample preparation and sample introduction in atomic spectroscopy. The most popular areas for development in sample preparation continuing to be dissolution/decomposition, separation and preconcentration, and solvent extraction, with the emphasis on the establishment of robust and valid methodology. The motives for this approach are usually being led by the necessity to develop simpler, low cost and safe methods. The importance of trace element determination","Atomic spectrometry update: Environmental analysis Abs: BIOSIS COPYRIGHT: BIOL ABS. This is the thirteenth annual review published in JAAS of the applications of atomic spectroscopy to the chemical analysis of environmental samples. The format used continues to be similar to that of previous years, highlighting the main features of this particular subject. Developments in instrumentation are not essentially a feature of this update, and so the emphasis is mainly with the establishment of reliable and robust methods of environmental analysis. The update does, however, focus on the areas of sampling, sample preparation and sample introduction in atomic spectroscopy. The most popular areas for development in sample preparation continuing to be dissolution/decomposition, separation and preconcentration, and solvent extraction, with the emphasis on the establishment of robust and valid methodology. The motives for this approach are usually being led by the necessity to develop simpler, low cost and safe methods. The importance of trace element determination"
1268322,Dreyer et al. 1997,Avoidable cancers in the Nordic countries: Occupation,"BIOSIS COPYRIGHT: BIOL ABS. A number of chemicals encountered predominantly in occupational settings have been causally linked with cancer in humans; furthermore, several industrial processes and occupations have been associated convincingly with increased rates of cancer, although the specific carcinogens remain to be identified. The tissues affected are mainly the epithelia) lining of the respiratory organs (nasal cavity, paranasal sinuses, larynx and lung), and urinary tract (renal parenchyma, renal pelvis and urinary bladder), the mesothelial linings, the bone marrow and the liver. During the period 1970-84, almost 4 million people (3.7 million men and 0.2 million women) in the Nordic countries were potentially exposed to above-average levels of one or more verified industrial carcinogens. It is expected that these exposures will result in a total of about 1,900 new cases of cancer every year in the Nordic countries around the year 2000, with 1,890 among men and fewer than 25 among women. The","Avoidable cancers in the Nordic countries: Occupation Abs: BIOSIS COPYRIGHT: BIOL ABS. A number of chemicals encountered predominantly in occupational settings have been causally linked with cancer in humans; furthermore, several industrial processes and occupations have been associated convincingly with increased rates of cancer, although the specific carcinogens remain to be identified. The tissues affected are mainly the epithelia) lining of the respiratory organs (nasal cavity, paranasal sinuses, larynx and lung), and urinary tract (renal parenchyma, renal pelvis and urinary bladder), the mesothelial linings, the bone marrow and the liver. During the period 1970-84, almost 4 million people (3.7 million men and 0.2 million women) in the Nordic countries were potentially exposed to above-average levels of one or more verified industrial carcinogens. It is expected that these exposures will result in a total of about 1,900 new cases of cancer every year in the Nordic countries around the year 2000, with 1,890 among men and fewer than 25 among women. The"
1268309,Hill 1997,SPECIATION OF TRACE METALS IN THE ENVIRONMENT,BIOSIS COPYRIGHT: BIOL ABS. RRM JOURNAL ARTICLE METHODOLOGY TOXICOLOGY ENVIRONMENTAL SCIENCES TRACE METALS TRACE METAL SPECIATION ENVIRONMENT SPECIATION ANALYSIS TOXICITY BIOAVAILABILITY BIOACCUMULATION ENVIRONMENTAL CHEMISTRY ANALYTICAL TECHNIQUES ANALYTICAL METHOD,SPECIATION OF TRACE METALS IN THE ENVIRONMENT Abs: BIOSIS COPYRIGHT: BIOL ABS. RRM JOURNAL ARTICLE METHODOLOGY TOXICOLOGY ENVIRONMENTAL SCIENCES TRACE METALS TRACE METAL SPECIATION ENVIRONMENT SPECIATION ANALYSIS TOXICITY BIOAVAILABILITY BIOACCUMULATION ENVIRONMENTAL CHEMISTRY ANALYTICAL TECHNIQUES ANALYTICAL METHOD
1268290,Dietrich and  Costa W 1997,CHEMICAL SPECIES,BIOSIS COPYRIGHT: BIOL ABS. RRM LITERATURE REVIEW WASTEWATER TREATMENT DRINKING WATER ELECTROPHORESIS ORGANIC CHEMICALS INORGANIC CHEMICALS METHODOLOGY POLLUTION ANALYTICAL METHOD,CHEMICAL SPECIES Abs: BIOSIS COPYRIGHT: BIOL ABS. RRM LITERATURE REVIEW WASTEWATER TREATMENT DRINKING WATER ELECTROPHORESIS ORGANIC CHEMICALS INORGANIC CHEMICALS METHODOLOGY POLLUTION ANALYTICAL METHOD
1268262,Pascucci and  Kowalak 1996,PUBLIC HEALTH BENEFITS OF USING ALGAE FOR SIMULTANEOUS MULTIPLE METAL EXTRACTION FROM WATERS,BIOSIS COPYRIGHT: BIOL ABS. RRM JOURNAL ARTICLE ALGAE POLLUTED WATERS HEAVY METALS ADSORPTION SIMULTANEOUS MULTIPLE EXTRACTION PUBLIC HEALTH BENEFITS POLLUTION,PUBLIC HEALTH BENEFITS OF USING ALGAE FOR SIMULTANEOUS MULTIPLE METAL EXTRACTION FROM WATERS Abs: BIOSIS COPYRIGHT: BIOL ABS. RRM JOURNAL ARTICLE ALGAE POLLUTED WATERS HEAVY METALS ADSORPTION SIMULTANEOUS MULTIPLE EXTRACTION PUBLIC HEALTH BENEFITS POLLUTION
1268246,Yuspa and  Shields 1997,ETIOLOGY OF CANCER CHEMICAL FACTORS,BIOSIS COPYRIGHT: BIOL ABS. RRM BOOK CHAPTER HUMAN ANIMAL PATIENT MODEL TUMOR BIOLOGY ETIOLOGY CANCER CHEMICAL CARCINOGENS MULTISTAGE CARCINOGENESIS DNA TUMOR SUPPRESSOR GENE TRANSFORMING GROWTH FACTOR-BETA GENETIC SUSCEPTIBILITY POPULATION-BASED RISK ASSESSMENT MOLECULAR EPIDEMIOLOGY HOST SUSCEPTIBILITY FACTORS INTERNAL DOSIMETRY EXPOSURE ASSESSMENT MUTATIONAL SPECTRUM LIVER CANCER AFLATOXIN NEOPLASTIC DISEASE DIGESTIVE SYSTEM DISEASE,ETIOLOGY OF CANCER CHEMICAL FACTORS Abs: BIOSIS COPYRIGHT: BIOL ABS. RRM BOOK CHAPTER HUMAN ANIMAL PATIENT MODEL TUMOR BIOLOGY ETIOLOGY CANCER CHEMICAL CARCINOGENS MULTISTAGE CARCINOGENESIS DNA TUMOR SUPPRESSOR GENE TRANSFORMING GROWTH FACTOR-BETA GENETIC SUSCEPTIBILITY POPULATION-BASED RISK ASSESSMENT MOLECULAR EPIDEMIOLOGY HOST SUSCEPTIBILITY FACTORS INTERNAL DOSIMETRY EXPOSURE ASSESSMENT MUTATIONAL SPECTRUM LIVER CANCER AFLATOXIN NEOPLASTIC DISEASE DIGESTIVE SYSTEM DISEASE
1268196,Veys 1996,ABC of work related disorders: Occupational cancers,"The first report of cancer caused by occupational exposure was in 1775 by Percival Pott, a British surgeon who described scrotal cancer in boy chimney sweeps. A century later, in 1895, Rehn, a German surgeon working in Frankfurt, treated a cluster of three cases of bladder cancer in workers at a local factory producing aniline dyestuffs from coal tar. Occupational cancer is any malignancy wholly or partly caused by exposures at the workplace or in occupation. Such exposure may be to a particular chemical (such as ?-naphthylamine), a physical agent (such as ionising radiation or a fibre like asbestos), a biological agent (such as hepatitis B virus), or an industrial process in which the specific carcinogen may elude precise definition (such as coke production). About 4% of all cancer deaths in people aged over 15 years may have an occupational cause. This translates into over 3000 male deaths in England and Wales from potentially preventable malignancies. The proportion occurring in women is probably less because of their lower potential for exposure.","ABC of work related disorders: Occupational cancers Abs: The first report of cancer caused by occupational exposure was in 1775 by Percival Pott, a British surgeon who described scrotal cancer in boy chimney sweeps. A century later, in 1895, Rehn, a German surgeon working in Frankfurt, treated a cluster of three cases of bladder cancer in workers at a local factory producing aniline dyestuffs from coal tar. Occupational cancer is any malignancy wholly or partly caused by exposures at the workplace or in occupation. Such exposure may be to a particular chemical (such as ?-naphthylamine), a physical agent (such as ionising radiation or a fibre like asbestos), a biological agent (such as hepatitis B virus), or an industrial process in which the specific carcinogen may elude precise definition (such as coke production). About 4% of all cancer deaths in people aged over 15 years may have an occupational cause. This translates into over 3000 male deaths in England and Wales from potentially preventable malignancies. The proportion occurring in women is probably less because of their lower potential for exposure."
1268188,Goodrich-Mahoney 1996,Constructed wetland treatment systems applied research program at the Electric Power Research Institute,"BIOSIS COPYRIGHT: BIOL ABS. The Electric Power Research Institute's (EPRI) Environmental and Health Sciences Business Unit, within the Environment Group, has initiated a multi-disciplinary applied research program to develop constructed wetland treatment systems as a cost-effective technology for the treatment of metal-bearing electric utility aqueous discharges. EPRI's program involves the building of constructed wetland treatment systems, collection of field data from these systems, and conduct of controlled laboratory experiments to more fully understand their functions and the factors affecting these functions. Both data collected through this program and existing data will be used to develop and deliver design criteria for the effective use of this technology to reduce or eliminate the risk that electric utilities will not meet regulatory-imposed effluent discharge limits. Currently, EPRI along with one of its members, is funding the construction of a state-of-the-art constructed wetland trea","Constructed wetland treatment systems applied research program at the Electric Power Research Institute Abs: BIOSIS COPYRIGHT: BIOL ABS. The Electric Power Research Institute's (EPRI) Environmental and Health Sciences Business Unit, within the Environment Group, has initiated a multi-disciplinary applied research program to develop constructed wetland treatment systems as a cost-effective technology for the treatment of metal-bearing electric utility aqueous discharges. EPRI's program involves the building of constructed wetland treatment systems, collection of field data from these systems, and conduct of controlled laboratory experiments to more fully understand their functions and the factors affecting these functions. Both data collected through this program and existing data will be used to develop and deliver design criteria for the effective use of this technology to reduce or eliminate the risk that electric utilities will not meet regulatory-imposed effluent discharge limits. Currently, EPRI along with one of its members, is funding the construction of a state-of-the-art constructed wetland trea"
1268167,Ybanez and  Montoro 1996,TRACE ELEMENT FOOD TOXICOLOGY AN OLD AND EVER-GROWING DISCIPLINE,BIOSIS COPYRIGHT: BIOL ABS. RRM LITERATURE REVIEW FOODS BEVERAGES TOXICITY FOOD RESIDUE HUMAN METHODOLOGY FOOD PRODUCTS STANDARDS LEGISLATION,TRACE ELEMENT FOOD TOXICOLOGY AN OLD AND EVER-GROWING DISCIPLINE Abs: BIOSIS COPYRIGHT: BIOL ABS. RRM LITERATURE REVIEW FOODS BEVERAGES TOXICITY FOOD RESIDUE HUMAN METHODOLOGY FOOD PRODUCTS STANDARDS LEGISLATION
1268141,Zemba et al. 1996,Quantitative risk assessment of stack emissions from municipal waste combustors,"BIOSIS COPYRIGHT: BIOL ABS. Multi-pathway risk assessment (MRA) is a tool for evaluating the possibility of adverse effects to human health that may result from contaminant releases from municipal solid waste combustors (MWCs) and other sources of air pollution. An MRA attempts to model the movement of pollutants within the environment to various points at which they may be contacted by people, beginning with inhalation of contaminated air and continuing with indirect pathways such as food chain exposures that entail contaminant transfer and accumulation through several media. MRAs of MWCs date back to the mid-1980s, and are rooted in methods developed to assess the consequences of radionuclide releases from nuclear power generation. A detailed example of a typical MRA is presented that follows the classic four-stage risk assessment paradigm (Valberg et al., 1995). MRA methods, however, continue to be enhanced and refined by recent research. A number of current risk assessment topics are explored","Quantitative risk assessment of stack emissions from municipal waste combustors Abs: BIOSIS COPYRIGHT: BIOL ABS. Multi-pathway risk assessment (MRA) is a tool for evaluating the possibility of adverse effects to human health that may result from contaminant releases from municipal solid waste combustors (MWCs) and other sources of air pollution. An MRA attempts to model the movement of pollutants within the environment to various points at which they may be contacted by people, beginning with inhalation of contaminated air and continuing with indirect pathways such as food chain exposures that entail contaminant transfer and accumulation through several media. MRAs of MWCs date back to the mid-1980s, and are rooted in methods developed to assess the consequences of radionuclide releases from nuclear power generation. A detailed example of a typical MRA is presented that follows the classic four-stage risk assessment paradigm (Valberg et al., 1995). MRA methods, however, continue to be enhanced and refined by recent research. A number of current risk assessment topics are explored"
1268131,Nickson et al. 1995,SOLID PHASE TECHNIQUES FOR THE PRECONCENTRATION OF TRACE METALS FROM NATURAL WATERS,BIOSIS COPYRIGHT: BIOL ABS. RRM LITERATURE REVIEW POLLUTION IMINODIACETATE BASED RESIN QUINOLIN-8-OL BASED RESIN DITHIOCARBAMATE BASED RESIN ANALYTICAL METHOD,SOLID PHASE TECHNIQUES FOR THE PRECONCENTRATION OF TRACE METALS FROM NATURAL WATERS Abs: BIOSIS COPYRIGHT: BIOL ABS. RRM LITERATURE REVIEW POLLUTION IMINODIACETATE BASED RESIN QUINOLIN-8-OL BASED RESIN DITHIOCARBAMATE BASED RESIN ANALYTICAL METHOD
1268125,Sokolov 1995,POSSIBILITIES TO OBTAIN ECOLOGICALLY SAFE CROP PRODUCTION UNDER CONDITIONS OF AGROSPHERE POLLUTION ECOTOXICOLOGICAL ASPECT. REPORT 1. THE MOST IMPORTANT NATURAL AND XENOBIOTIC POLLUTANTS CHARACTERISTICS SOURCES DOCUMENTS,BIOSIS COPYRIGHT: BIOL ABS. RRM RESEARCH ARTICLE HEAVY METALS RADIONUCLIDES POLYCHLORINATED BIPHENYLS FOOD SAFETY AGRICULTURAL LAND USE MAXIMUM PERMISSIBLE CONCENTRATION ENVIRONMENTAL CONTROL,POSSIBILITIES TO OBTAIN ECOLOGICALLY SAFE CROP PRODUCTION UNDER CONDITIONS OF AGROSPHERE POLLUTION ECOTOXICOLOGICAL ASPECT. REPORT 1. THE MOST IMPORTANT NATURAL AND XENOBIOTIC POLLUTANTS CHARACTERISTICS SOURCES DOCUMENTS Abs: BIOSIS COPYRIGHT: BIOL ABS. RRM RESEARCH ARTICLE HEAVY METALS RADIONUCLIDES POLYCHLORINATED BIPHENYLS FOOD SAFETY AGRICULTURAL LAND USE MAXIMUM PERMISSIBLE CONCENTRATION ENVIRONMENTAL CONTROL
1268101,Vainio et al. 1995,Identification of human carcinogenic risk in IARC Monographs,"BIOSIS COPYRIGHT: BIOL ABS. For more than twenty years, the IARC has been evaluating the carcinogenic risk to humans of chemicals, groups of chemical, complex mixtures, occupational exposures, behavioral and life-style exposures, biological agents, such as bacteria and viruses, and physical agents, such as radiation, on the basis of published studies of carcinogenicity in humans and laboratory animals. This paper includes the list established by IARC of substances carcinogenic to humans.","Identification of human carcinogenic risk in IARC Monographs Abs: BIOSIS COPYRIGHT: BIOL ABS. For more than twenty years, the IARC has been evaluating the carcinogenic risk to humans of chemicals, groups of chemical, complex mixtures, occupational exposures, behavioral and life-style exposures, biological agents, such as bacteria and viruses, and physical agents, such as radiation, on the basis of published studies of carcinogenicity in humans and laboratory animals. This paper includes the list established by IARC of substances carcinogenic to humans."
1268063,Moeller et al. 1994,FUTURE RESEARCH NEEDS ASSOCIATED WITH THE ASSESSMENT OF POTENTIAL HUMAN HEALTH RISKS FROM EXPOSURE TO TOXIC AMBIENT AIR POLLUTANTS,BIOSIS COPYRIGHT: BIOL ABS. RRM MEETING REPORT BIOMARKERS BIOASSAY EPIDEMIOLOGY ANALYTICAL METHOD,FUTURE RESEARCH NEEDS ASSOCIATED WITH THE ASSESSMENT OF POTENTIAL HUMAN HEALTH RISKS FROM EXPOSURE TO TOXIC AMBIENT AIR POLLUTANTS Abs: BIOSIS COPYRIGHT: BIOL ABS. RRM MEETING REPORT BIOMARKERS BIOASSAY EPIDEMIOLOGY ANALYTICAL METHOD
1268057,Grass and  Jenkins 1994,"Biomass fueled fluidized bed combustion: Atmospheric emissions, emission control devices and environmental regulations","BIOSIS COPYRIGHT: BIOL ABS. Fluidized bed combustors have become the technological choice for power generation from biomass fuels in California. Atmospheric emission data obtained during compliance tests are compared for five operating 18 to 32 MW fluidized bed combustion power plants. The discussion focuses on the impact of fuel properties and boiler design criteria on the emission of pollutants, the efficiency of pollution control devices, and regulations affecting atmospheric emissions. Stack NOx emission factors are shown not to vary substantially among the five plants which burn fuels with nitrogen concentrations between 0.3 and 1.1% dry weight. With reference to previous works, it is suggested that fuel nitrogen to NOx conversion rates gradually level off at fuel nitrogen concentrations above 0.15%. Prompt NOx formation mechanisms are suggested to be important in addition to fuel NOx mechanisms, compensating for reduced formation of thermal NOx in fluidized bed combustors. This may limit the","Biomass fueled fluidized bed combustion: Atmospheric emissions, emission control devices and environmental regulations Abs: BIOSIS COPYRIGHT: BIOL ABS. Fluidized bed combustors have become the technological choice for power generation from biomass fuels in California. Atmospheric emission data obtained during compliance tests are compared for five operating 18 to 32 MW fluidized bed combustion power plants. The discussion focuses on the impact of fuel properties and boiler design criteria on the emission of pollutants, the efficiency of pollution control devices, and regulations affecting atmospheric emissions. Stack NOx emission factors are shown not to vary substantially among the five plants which burn fuels with nitrogen concentrations between 0.3 and 1.1% dry weight. With reference to previous works, it is suggested that fuel nitrogen to NOx conversion rates gradually level off at fuel nitrogen concentrations above 0.15%. Prompt NOx formation mechanisms are suggested to be important in addition to fuel NOx mechanisms, compensating for reduced formation of thermal NOx in fluidized bed combustors. This may limit the"
1268036,Chou and  Hee S 1994,Bioassay-driven analysis of chewing tobacco extracts,"BIOSIS COPYRIGHT: BIOL ABS. The aims were to develop a method to simulate extraction of toxic components into human saliva, to identify these components through bioassay-driven analyses using the Microtox test, and to quantify the toxic compounds. Chewing tobacco extractions into artificial saliva simulated oral chewing conditions. The Microtox bioassay-directed subfractionation scheme identified acutely toxic components in chewing tobacco extracts. GC-MS identified and quantified the toxic components. The subfractionation (pH 7 extraction, pH 2 extraction, then pH 10 extraction using organic solvents) scheme was shown to be comparable to biological digestive sequences and to simulate nicotine bioavailability. The low toxicity of artificial saliva allowed development of a sensitive bioassay. Nicotine was the major acutely toxic agent detected. Classification by Draize ocular irritative categories showed that leached nicotine concentrations were mildly to moderately irritating. Thus, the Microtox","Bioassay-driven analysis of chewing tobacco extracts Abs: BIOSIS COPYRIGHT: BIOL ABS. The aims were to develop a method to simulate extraction of toxic components into human saliva, to identify these components through bioassay-driven analyses using the Microtox test, and to quantify the toxic compounds. Chewing tobacco extractions into artificial saliva simulated oral chewing conditions. The Microtox bioassay-directed subfractionation scheme identified acutely toxic components in chewing tobacco extracts. GC-MS identified and quantified the toxic components. The subfractionation (pH 7 extraction, pH 2 extraction, then pH 10 extraction using organic solvents) scheme was shown to be comparable to biological digestive sequences and to simulate nicotine bioavailability. The low toxicity of artificial saliva allowed development of a sensitive bioassay. Nicotine was the major acutely toxic agent detected. Classification by Draize ocular irritative categories showed that leached nicotine concentrations were mildly to moderately irritating. Thus, the Microtox"
1268001,Bostick and  Hermes 1993,CONTROL OF REGULATED METALS AT DOE OAK RIDGE RESERVATION SITES,BIOSIS COPYRIGHT: BIOL ABS. RRM MEETING PAPER DEPARTMENT OF ENERGY RADIOACTIVE WASTE TREATMENT DECONTAMINATION URANIUM METALS TENNESSEE USA,CONTROL OF REGULATED METALS AT DOE OAK RIDGE RESERVATION SITES Abs: BIOSIS COPYRIGHT: BIOL ABS. RRM MEETING PAPER DEPARTMENT OF ENERGY RADIOACTIVE WASTE TREATMENT DECONTAMINATION URANIUM METALS TENNESSEE USA
1267930,Benfenati et al. 1992,Characterization of organic and inorganic pollutants in the Adige river (Italy),"BIOSIS COPYRIGHT: BIOL ABS. Samples of raw water from the Adige river, Italy, were collected at 19 sampling stations in the Trento province, twice in one year. Organic and inorganic analyses were done on these samples. COD, BOD, TOC, inorganic nitrogen, phosphate, and several metals were measured. The organic pollutants found included xylenes, methylisobutylketone, naphthalene, benzophenone, and pyrene. Industrial activities and urban effluents were the origin of most of the pollutants.","Characterization of organic and inorganic pollutants in the Adige river (Italy) Abs: BIOSIS COPYRIGHT: BIOL ABS. Samples of raw water from the Adige river, Italy, were collected at 19 sampling stations in the Trento province, twice in one year. Organic and inorganic analyses were done on these samples. COD, BOD, TOC, inorganic nitrogen, phosphate, and several metals were measured. The organic pollutants found included xylenes, methylisobutylketone, naphthalene, benzophenone, and pyrene. Industrial activities and urban effluents were the origin of most of the pollutants."
1267889,Behmanesh et al. 1992,Flow rates and compositions of incinerated waste streams in the United States,"BIOSIS COPYRIGHT: BIOL ABS. The quantity and composition of RCRA hazardous wastes incinerated during 1986 were examined using the National Hazardous Waste Survey. This survey, collected for U.S. EPA by the Research Triangle Institute, is the most extensive examination of hazardous waste generation and management available. The survey data show that although a wide variety of hazardous wastes were treated by incineration, more than 75 percent of incinerated waste streams were from chemical manufacturing. The survey data also show that more than 9 percent of the incinerated wastes were treated by incinerators located at the facility generating the waste. Despite the predominance of a single industrial sector in generating incinerated hazardous wastes, the compositional profile of the wastes is far from uniform. To illustrate this variability, the metals and chlorine content of the wastes are reported along with the sources of the metal and chlorine loadings.","Flow rates and compositions of incinerated waste streams in the United States Abs: BIOSIS COPYRIGHT: BIOL ABS. The quantity and composition of RCRA hazardous wastes incinerated during 1986 were examined using the National Hazardous Waste Survey. This survey, collected for U.S. EPA by the Research Triangle Institute, is the most extensive examination of hazardous waste generation and management available. The survey data show that although a wide variety of hazardous wastes were treated by incineration, more than 75 percent of incinerated waste streams were from chemical manufacturing. The survey data also show that more than 9 percent of the incinerated wastes were treated by incinerators located at the facility generating the waste. Despite the predominance of a single industrial sector in generating incinerated hazardous wastes, the compositional profile of the wastes is far from uniform. To illustrate this variability, the metals and chlorine content of the wastes are reported along with the sources of the metal and chlorine loadings."
1267647,Reinthaler et al. 1988,DISPOSAL OF CHEMICALS IN HOSPITAL AND OTHER MEDICAL AREAS,BIOSIS COPYRIGHT: BIOL ABS. RRM WASTE WATER POLLUTION PREVENTION,DISPOSAL OF CHEMICALS IN HOSPITAL AND OTHER MEDICAL AREAS Abs: BIOSIS COPYRIGHT: BIOL ABS. RRM WASTE WATER POLLUTION PREVENTION
1267636,Sims et al. 1988,HUMAN HEALTH EFFECTS ASSAYS,BIOSIS COPYRIGHT: BIOL ABS. RRM REVIEW RISK ASSESSMENT CARCINOGENICITY TESTING TOXICITY TESTING ENVIRONMENTAL POLLUTANT MUTAGEN WASTEWATER WATER POLLUTION,HUMAN HEALTH EFFECTS ASSAYS Abs: BIOSIS COPYRIGHT: BIOL ABS. RRM REVIEW RISK ASSESSMENT CARCINOGENICITY TESTING TOXICITY TESTING ENVIRONMENTAL POLLUTANT MUTAGEN WASTEWATER WATER POLLUTION
1267576,Reish et al. 1987,EFFECTS ON SALTWATER ORGANISMS,BIOSIS COPYRIGHT: BIOL ABS. RRM REVIEW FISH SHELLFISH ALGA MAMMAL METALS WATER POLLUTION DREDGING DUMPING WASTE DISPOSAL MINING INDUSTRY,EFFECTS ON SALTWATER ORGANISMS Abs: BIOSIS COPYRIGHT: BIOL ABS. RRM REVIEW FISH SHELLFISH ALGA MAMMAL METALS WATER POLLUTION DREDGING DUMPING WASTE DISPOSAL MINING INDUSTRY
1267567,Maccarthy et al. 1987,WATER ANALYSIS,BIOSIS COPYRIGHT: BIOL ABS. RRM REVIEW PESTICIDE RADIONUCLIDES METAL POLLUTION WATER POLLUTION SAMPLING,WATER ANALYSIS Abs: BIOSIS COPYRIGHT: BIOL ABS. RRM REVIEW PESTICIDE RADIONUCLIDES METAL POLLUTION WATER POLLUTION SAMPLING
1267528,Berrow and  Burridge 1984,UPTAKE DISTRIBUTION AND EFFECTS IN PLANTS,BIOSIS COPYRIGHT: BIOL ABS. RRM AIR POLLUTION SOIL-ROOT UPTAKE METAL POLLUTION,UPTAKE DISTRIBUTION AND EFFECTS IN PLANTS Abs: BIOSIS COPYRIGHT: BIOL ABS. RRM AIR POLLUTION SOIL-ROOT UPTAKE METAL POLLUTION
1267526,Stoeppler and  Nuernberg 1984,THE ANALYSIS OF METALS AND THEIR COMPOUNDS,BIOSIS COPYRIGHT: BIOL ABS. RRM ANIMAL METAL POLLUTION WATER POLLUTION WASTEWATER,THE ANALYSIS OF METALS AND THEIR COMPOUNDS Abs: BIOSIS COPYRIGHT: BIOL ABS. RRM ANIMAL METAL POLLUTION WATER POLLUTION WASTEWATER
1260427,Otmane et al. 1992,Phagocytosis and Metabolization of Welding Fumes by Guinea Pig Alveolar Macrophages in Culture,"The metabolism and incorporation of welding fumes by guinea-pig alveolar macrophages (GPAMs) in primary culture were studied. Macrophages were obtained from Hartley-albino-guinea-pigs. GPAMs were incubated for 3 days with manual metal arc/stainless steel (MMA) fume at 2.5, 5 or 10 micrograms/milliliter (microg/ml), or with metal inert gas (MIG) fume at 50, 100 or 200microg/ml. The welding fumes were phagocytized by GPAMs in primary culture. The relatively high cytotoxic effect was confirmed for these cells. Light microscopy permitted estimation of a survival rate of 10% in cultures with 10 micrograms MMA/SS welding fume per milliliter. The primary ultrastructural modification of GPAMs was an increase in the number of microvilli with respect to the control cells. Areas with a high density of microvilli were often observed for all the welding fumes tested. There was evidence of a decrease in the amount of manganese in phagocytized particles when compared to extracellular areas. A very significant increase in beta-glucuronidase activity was noted at very low concentrations. The authors suggest that the high cytotoxic effect of the MMA/SS fume may be due to the presence of a soluble hexavalent chromium (7440473) compound, estimated at 3.6% by content. The authors conclude that the MMA/SS welding fumes had a rapid and important cytotoxic effect on GPAMs. Tiny particles bound preferentially to membranes, surfactant, and euchromatin were observed. The cytotoxic effect of welding fumes depended primarily on its solubilization rate and on the bioavailability of its constituents./ETIOLOGY","Phagocytosis and Metabolization of Welding Fumes by Guinea Pig Alveolar Macrophages in Culture Abs: The metabolism and incorporation of welding fumes by guinea-pig alveolar macrophages (GPAMs) in primary culture were studied. Macrophages were obtained from Hartley-albino-guinea-pigs. GPAMs were incubated for 3 days with manual metal arc/stainless steel (MMA) fume at 2.5, 5 or 10 micrograms/milliliter (microg/ml), or with metal inert gas (MIG) fume at 50, 100 or 200microg/ml. The welding fumes were phagocytized by GPAMs in primary culture. The relatively high cytotoxic effect was confirmed for these cells. Light microscopy permitted estimation of a survival rate of 10% in cultures with 10 micrograms MMA/SS welding fume per milliliter. The primary ultrastructural modification of GPAMs was an increase in the number of microvilli with respect to the control cells. Areas with a high density of microvilli were often observed for all the welding fumes tested. There was evidence of a decrease in the amount of manganese in phagocytized particles when compared to extracellular areas. A very significant increase in beta-glucuronidase activity was noted at very low concentrations. The authors suggest that the high cytotoxic effect of the MMA/SS fume may be due to the presence of a soluble hexavalent chromium (7440473) compound, estimated at 3.6% by content. The authors conclude that the MMA/SS welding fumes had a rapid and important cytotoxic effect on GPAMs. Tiny particles bound preferentially to membranes, surfactant, and euchromatin were observed. The cytotoxic effect of welding fumes depended primarily on its solubilization rate and on the bioavailability of its constituents./ETIOLOGY"
1260426,Lewalter and  Korallus 1989,The significance of ascorbic acid and glutathione for chromate metabolism in man,"The roles of ascorbic-acid (AS) and glutathione (GSH) in the human metabolism of chromate (13907454) were studied. Blood concentrations of chromium(VI) (18540299) (Cr(VI)) exceeding 10 micrograms per liter were associated with penetration of Cr(VI) into erythrocytes, which was inhibited by individual AS threshold doses. Isolated erythrocytes had no significant differences in Cr(VI) penetration between individuals. Cr(VI) which had penetrated into erythrocytes in-vitro was not removed by repeated dialysis. GSH inhibition by maleic-ester resulted in a decrease of the Cr(VI) irreversibly bound in erythrocytes. The presence of greater than 10 millimolar AS in blood inhibited the penetration of Cr(VI) into erythrocytes. Plasma AS levels ranged from less than 1.0 to 20 milligrams per liter (mg/l) for different individuals, while GSH levels were less than 1.0mg/l. By blood spiking experiments, AS appeared to be mainly responsible for erythrocyte chromate loading capacity when plasma components below 8000 daltons molecular weight were considered. The authors conclude that Cr(VI) loading of erythrocytes will occur only in the absence of sufficient thiol group redox equivalents in the plasma and erythrocytes. High dose AS therapy was recommended for cases of chromate intoxication, since the short half life of GSH in plasma precludes its therapeutic utility.","The significance of ascorbic acid and glutathione for chromate metabolism in man Abs: The roles of ascorbic-acid (AS) and glutathione (GSH) in the human metabolism of chromate (13907454) were studied. Blood concentrations of chromium(VI) (18540299) (Cr(VI)) exceeding 10 micrograms per liter were associated with penetration of Cr(VI) into erythrocytes, which was inhibited by individual AS threshold doses. Isolated erythrocytes had no significant differences in Cr(VI) penetration between individuals. Cr(VI) which had penetrated into erythrocytes in-vitro was not removed by repeated dialysis. GSH inhibition by maleic-ester resulted in a decrease of the Cr(VI) irreversibly bound in erythrocytes. The presence of greater than 10 millimolar AS in blood inhibited the penetration of Cr(VI) into erythrocytes. Plasma AS levels ranged from less than 1.0 to 20 milligrams per liter (mg/l) for different individuals, while GSH levels were less than 1.0mg/l. By blood spiking experiments, AS appeared to be mainly responsible for erythrocyte chromate loading capacity when plasma components below 8000 daltons molecular weight were considered. The authors conclude that Cr(VI) loading of erythrocytes will occur only in the absence of sufficient thiol group redox equivalents in the plasma and erythrocytes. High dose AS therapy was recommended for cases of chromate intoxication, since the short half life of GSH in plasma precludes its therapeutic utility."
1260424,Novakova 1978,A study on the isolated and combined action of manganese with chromium of six valency,"HEEP COPYRIGHT: BIOL ABS. The isolated and combined actions of Mn and Cr(VI) on some blood, enzymic and other indices in rabbits with and without experimental hypercholesteremia were determined. There was anemia in the animals with experimental atherosclerosis, whose development was slightly delayed by Cr(VI). The examined microelements affected liver function, impaired liver and renal parenchyma, disturbed tissue respiration and oxidative-reparative processes in the organism (mostly manifested in animals with experimental hypercholesteremia) and more marked in those animals treated with Mn.","A study on the isolated and combined action of manganese with chromium of six valency Abs: HEEP COPYRIGHT: BIOL ABS. The isolated and combined actions of Mn and Cr(VI) on some blood, enzymic and other indices in rabbits with and without experimental hypercholesteremia were determined. There was anemia in the animals with experimental atherosclerosis, whose development was slightly delayed by Cr(VI). The examined microelements affected liver function, impaired liver and renal parenchyma, disturbed tissue respiration and oxidative-reparative processes in the organism (mostly manifested in animals with experimental hypercholesteremia) and more marked in those animals treated with Mn."
1260423,Ren and  Zhu 2007,,"Objective: To investigate the expression of vimentin in adult rat testis after combination of nickel ion (Ni2+) and hexavalent chromium (Cr6+) exposure. Method: A total of 32 male SD rats were divided into 8 groups randomly. The groups were group A (control group), group B (0.9% NaCl), group C (5 mg/kg Ni2+), group D (50 mg/kg Ni2+), group E (2.5 mg/kg Cr 6+), group F (6.5 mg/kg Cr6+), group G (5 mg/kg Ni2+ + 2.5 mg/kg Cr6+), and group H (50 mg/kg Ni2+ + 6.5 mg/kg Cr6+). Animals in groups B-H were administrated by gastric perfusion for 4 months. The expression of vimentin in testis was detected by immunohistochemistry method. Results: Compared with control, the expression of vimentin in Sertoli cells was significantly decreased in groups C-H (P<0.01), and group G had more decrease than group C or E (P<0.01), and group H and D or F (P<0.01). In testicular interstitium, the expression of vimentin in groups C-H had significant decrease compared with control group (P<0.01), and group G had more decrease than group C or E (P<0.01), and group H and D or F (P<0.01). Conclusion: Expression of vimentin of Sertoli cells and testicular interstitium in male rat would be significantly decreased after Ni2+ or Cr 6+ exposure. The combination of Ni2+ and Cr6+ could cause more damage to testis."," Abs: Objective: To investigate the expression of vimentin in adult rat testis after combination of nickel ion (Ni2+) and hexavalent chromium (Cr6+) exposure. Method: A total of 32 male SD rats were divided into 8 groups randomly. The groups were group A (control group), group B (0.9% NaCl), group C (5 mg/kg Ni2+), group D (50 mg/kg Ni2+), group E (2.5 mg/kg Cr 6+), group F (6.5 mg/kg Cr6+), group G (5 mg/kg Ni2+ + 2.5 mg/kg Cr6+), and group H (50 mg/kg Ni2+ + 6.5 mg/kg Cr6+). Animals in groups B-H were administrated by gastric perfusion for 4 months. The expression of vimentin in testis was detected by immunohistochemistry method. Results: Compared with control, the expression of vimentin in Sertoli cells was significantly decreased in groups C-H (P<0.01), and group G had more decrease than group C or E (P<0.01), and group H and D or F (P<0.01). In testicular interstitium, the expression of vimentin in groups C-H had significant decrease compared with control group (P<0.01), and group G had more decrease than group C or E (P<0.01), and group H and D or F (P<0.01). Conclusion: Expression of vimentin of Sertoli cells and testicular interstitium in male rat would be significantly decreased after Ni2+ or Cr 6+ exposure. The combination of Ni2+ and Cr6+ could cause more damage to testis."
1260421,Maruyama 1983,The effect on mice of long-term oral administration of trivalent and hexavalent chromium,"Male mice were provided with drinking water containing 25, 50 and 100mg/l chromium (Cr) in trivalent and hexavalent forms for a year, and the effects on blood composition and the content of copper, Cr, iron (Fe) and zinc in various organs were determined at monthly intervals in sacrificed animals. Cr caused slight anaemia which was more severe with the trivalent than with the hexavalent form. Cholesterol in plasma decreased after Cr administration, and the degree was greater with hexavalent than with trivalent Cr. The Fe content of the liver, spleen and testes were decreased after hexavalent Cr administration.","The effect on mice of long-term oral administration of trivalent and hexavalent chromium Abs: Male mice were provided with drinking water containing 25, 50 and 100mg/l chromium (Cr) in trivalent and hexavalent forms for a year, and the effects on blood composition and the content of copper, Cr, iron (Fe) and zinc in various organs were determined at monthly intervals in sacrificed animals. Cr caused slight anaemia which was more severe with the trivalent than with the hexavalent form. Cholesterol in plasma decreased after Cr administration, and the degree was greater with hexavalent than with trivalent Cr. The Fe content of the liver, spleen and testes were decreased after hexavalent Cr administration."
1260420,Hussein et al. 1997,Subacute toxicity of chromium compounds in rats,"BIOSIS COPYRIGHT: BIOL ABS. Chromium is an environmentally significant human carcinogen with a complicated metabolism and an unknown mechanism of mutagenesis. Chromium (VI) is taken up by cells as anions and is reduced intracellularly via reactive intermediates to stable Cr (III) species. A comparison was made between the effects of Cr (III) and Cr (VI). Two groups of male adult rats weighing 150-250 g were intraperitoneally administered with Cr (III) and Cr (VI) in doses of 5 mg/kg body weight daily for 10 days. A third group of saline-injected rats was used as a control. At the end of the experiments blood samples were collected for haematological and blood indices. Serum was prepared for the estimation of creatinine, uric acid, total proteins, cholesterol, triglycerides, glucose, aspartate amino transferase, alanine amino transferase and alkaline phosphatase. Data revealed the high toxicity of Cr (VI) compared with the moderate toxicity of Cr (III) on rats. Chromium-induced toxicity was evaluat","Subacute toxicity of chromium compounds in rats Abs: BIOSIS COPYRIGHT: BIOL ABS. Chromium is an environmentally significant human carcinogen with a complicated metabolism and an unknown mechanism of mutagenesis. Chromium (VI) is taken up by cells as anions and is reduced intracellularly via reactive intermediates to stable Cr (III) species. A comparison was made between the effects of Cr (III) and Cr (VI). Two groups of male adult rats weighing 150-250 g were intraperitoneally administered with Cr (III) and Cr (VI) in doses of 5 mg/kg body weight daily for 10 days. A third group of saline-injected rats was used as a control. At the end of the experiments blood samples were collected for haematological and blood indices. Serum was prepared for the estimation of creatinine, uric acid, total proteins, cholesterol, triglycerides, glucose, aspartate amino transferase, alanine amino transferase and alkaline phosphatase. Data revealed the high toxicity of Cr (VI) compared with the moderate toxicity of Cr (III) on rats. Chromium-induced toxicity was evaluat"
1260419,Finley and  Paustenbach 1997,Using applied research to reduce uncertainty in health risk assessment: Five case studies involving human exposure to chromium in soil and groundwater,"BIOSIS COPYRIGHT: BIOL ABS. In this article, five case studies are presented that involve original research conducted in order to better understand the potential health risks associated with human exposure to Cr(VI) in soils and groundwater. Each study was designed to address a specific data gap, and of these studies involved the use of human volunteers and/or the study of human biological fluids. The results of this research can be summarized as follows: (1) soil concentrations of approximately 1240 ppm Cr(VI) or less do not elicit allergic contact dermatitis (ACD) in a vast majority of the general population (>99.9%), and soil concentrations much higher than this value are also health protective if the Cr(VI) is not readily bioavailable, (2) exposure to soil concentrations up to 400 ppm total chromium is unlikely to influence urinary chromium levels; (3) the human gastrointestinal tract can reduce ingested Cr(VI) to Cr(III) at concentrations up to 10 mg Cr(VI)/l; and (4) at water concentratio","Using applied research to reduce uncertainty in health risk assessment: Five case studies involving human exposure to chromium in soil and groundwater Abs: BIOSIS COPYRIGHT: BIOL ABS. In this article, five case studies are presented that involve original research conducted in order to better understand the potential health risks associated with human exposure to Cr(VI) in soils and groundwater. Each study was designed to address a specific data gap, and of these studies involved the use of human volunteers and/or the study of human biological fluids. The results of this research can be summarized as follows: (1) soil concentrations of approximately 1240 ppm Cr(VI) or less do not elicit allergic contact dermatitis (ACD) in a vast majority of the general population (>99.9%), and soil concentrations much higher than this value are also health protective if the Cr(VI) is not readily bioavailable, (2) exposure to soil concentrations up to 400 ppm total chromium is unlikely to influence urinary chromium levels; (3) the human gastrointestinal tract can reduce ingested Cr(VI) to Cr(III) at concentrations up to 10 mg Cr(VI)/l; and (4) at water concentratio"
1260417,Sheyko and  Balezin 1993,Morphostructural changes in rat gonads from hexavalent chromium,,Morphostructural changes in rat gonads from hexavalent chromium Abs: 
1260416,Alcedo and  Wetterham 1990,EFFECT OF CHROMIUM-VI ON METALLOTHIONEIN GENE EXPRESSION,BIOSIS COPYRIGHT: BIOL ABS. RRM ABSTRACT CHICK EMBRYO LIVER CARCINOGENIC COMPOUNDS MESSENGER RNA ZINC,EFFECT OF CHROMIUM-VI ON METALLOTHIONEIN GENE EXPRESSION Abs: BIOSIS COPYRIGHT: BIOL ABS. RRM ABSTRACT CHICK EMBRYO LIVER CARCINOGENIC COMPOUNDS MESSENGER RNA ZINC
1260415,Wiegand and  Ottenwaelder 1985,Molecular mechanisms for the in-vitro reduction of chromium-VI to chromium-III by glutathione and their relevance for the metabolism of chromates,,Molecular mechanisms for the in-vitro reduction of chromium-VI to chromium-III by glutathione and their relevance for the metabolism of chromates Abs: 
1260414,Myers et al. 1999,Naphthoquinones stimulate the rate of reduction of hexavalent chromium by human microsomes,"BIOSIS COPYRIGHT: BIOL ABS. The NADPH*-dependent reduction of chromium(VI), a known carcinogen, by human hepatic microsomes was significantly stimulated by 1,4-naphthoquinone (NQ) or 2-methyl-1,4-naphthoquinone (MNQ) under anaerobic conditions. The most pronounced stimulation occurred when quinone concentrations were increased from 1 to 5 muM. Additional, but smaller, increases were seen with subsequent increases in quinone concentration above 5 muM. These quinones also caused pronounced stimulation of chromium(VI) reducti pport of this occurrence, NQ and MNQ caused a marked stimulation of NADPH consumption under aerobic conditions, with the resulting generation of superoxide. NQ and MNQ also stimulated chromium(VI) reduction to different extents under room air, depending on the relative ratios of chromium(VI) to oxygen (O2). This suggests that O2 is able to compete with chromium(VI) for the oxidation of the semiquinones. Since chromium(VI) reduction is associated with the formation of reactive chromium intermedia","Naphthoquinones stimulate the rate of reduction of hexavalent chromium by human microsomes Abs: BIOSIS COPYRIGHT: BIOL ABS. The NADPH*-dependent reduction of chromium(VI), a known carcinogen, by human hepatic microsomes was significantly stimulated by 1,4-naphthoquinone (NQ) or 2-methyl-1,4-naphthoquinone (MNQ) under anaerobic conditions. The most pronounced stimulation occurred when quinone concentrations were increased from 1 to 5 muM. Additional, but smaller, increases were seen with subsequent increases in quinone concentration above 5 muM. These quinones also caused pronounced stimulation of chromium(VI) reducti pport of this occurrence, NQ and MNQ caused a marked stimulation of NADPH consumption under aerobic conditions, with the resulting generation of superoxide. NQ and MNQ also stimulated chromium(VI) reduction to different extents under room air, depending on the relative ratios of chromium(VI) to oxygen (O2). This suggests that O2 is able to compete with chromium(VI) for the oxidation of the semiquinones. Since chromium(VI) reduction is associated with the formation of reactive chromium intermedia"
1260413,De Flora et al. 1989,Mechanistic aspects of chromium carcinogenicity,"There is no doubt that chromium has been the most extensively investigated metal with respect to the assessment of long-term effects and to the evaluation of the underlying mechanisms. Notwithstanding the huge data-base available in the literature, many aspects, bearing both scientific and practical interest, are still unclear or controversial. This paper will briefly discuss some relevant problems, including carcinogenicity and genotoxicity of chromium compounds as related to their valency and solubility, interactions with other compounds, bioavailability to target cells and molecules, interconversion processes between different oxidation states in various body areas and cell compartments, mechanisms of chromium metabolism and carcinogenicity, and existence of thresholds in chromium carcinogenesis.","Mechanistic aspects of chromium carcinogenicity Abs: There is no doubt that chromium has been the most extensively investigated metal with respect to the assessment of long-term effects and to the evaluation of the underlying mechanisms. Notwithstanding the huge data-base available in the literature, many aspects, bearing both scientific and practical interest, are still unclear or controversial. This paper will briefly discuss some relevant problems, including carcinogenicity and genotoxicity of chromium compounds as related to their valency and solubility, interactions with other compounds, bioavailability to target cells and molecules, interconversion processes between different oxidation states in various body areas and cell compartments, mechanisms of chromium metabolism and carcinogenicity, and existence of thresholds in chromium carcinogenesis."
1260403,Gao et al. 1994,Use of molecular epidemiological techniques in a pilot study on workers exposed to chromium,"OBJECTIVES: Molecular epidemiological techniques, capable of detecting damage to DNA, were used to see if such damage occurred in the lymphocytes of a group of workers exposed to chromium. The two aims of this pilot study were to see if these new techniques might make useful biological monitoring tools for workers exposed to chromium and also, to help assess whether the current occupational exposure limit for chromium (VI) was sufficiently protective in this specific working situation. METHODS: Volunteer groups of 10 workers exposed to chromium and 10 non-exposed workers provided urine and blood samples towards the end of the working week. Chromium concentrations were measured in whole blood, plasma, lymphocytes, and urine. Lymphocytes were used to examine two forms of DNA damage in the two groups; these were the level of DNA strand breakage and, the production of 8-hydroxydeoxyguanosine. RESULTS: Chromium concentration in whole blood, plasma, and urine of workers exposed to chromium was significantly raised (P < 0.01) compared with non-exposed controls, but in isolated lymphocytes, there was only a modest but significant (P < 0.05) increase in chromium in the group exposed to chromium. There was no difference in the levels of DNA strand breaks or 8-hydroxydeoxyguanosine between the groups. Air monitoring for chromium was not undertaken but current levels for the group exposed to chromium were reported to be around 0.01 mg/m3, which is 20% of the current United Kingdom occupational exposure limit. CONCLUSIONS: We were unable to detect any damage in lymphocytic DNA due to exposure to chromium. This may have been due to the low chromium exposure (< 20% of the United Kingdom occupational exposure limit), the ability of plasma to detoxify chromium (VI) to chromium (III) before it reached the lymphocytes, or perhaps the insensitivity of the molecular techniques used. It is now important to test these and other such techniques on groups exposed to levels closer to the United Kingdom occupational exposure limit.","Use of molecular epidemiological techniques in a pilot study on workers exposed to chromium Abs: OBJECTIVES: Molecular epidemiological techniques, capable of detecting damage to DNA, were used to see if such damage occurred in the lymphocytes of a group of workers exposed to chromium. The two aims of this pilot study were to see if these new techniques might make useful biological monitoring tools for workers exposed to chromium and also, to help assess whether the current occupational exposure limit for chromium (VI) was sufficiently protective in this specific working situation. METHODS: Volunteer groups of 10 workers exposed to chromium and 10 non-exposed workers provided urine and blood samples towards the end of the working week. Chromium concentrations were measured in whole blood, plasma, lymphocytes, and urine. Lymphocytes were used to examine two forms of DNA damage in the two groups; these were the level of DNA strand breakage and, the production of 8-hydroxydeoxyguanosine. RESULTS: Chromium concentration in whole blood, plasma, and urine of workers exposed to chromium was significantly raised (P < 0.01) compared with non-exposed controls, but in isolated lymphocytes, there was only a modest but significant (P < 0.05) increase in chromium in the group exposed to chromium. There was no difference in the levels of DNA strand breaks or 8-hydroxydeoxyguanosine between the groups. Air monitoring for chromium was not undertaken but current levels for the group exposed to chromium were reported to be around 0.01 mg/m3, which is 20% of the current United Kingdom occupational exposure limit. CONCLUSIONS: We were unable to detect any damage in lymphocytic DNA due to exposure to chromium. This may have been due to the low chromium exposure (< 20% of the United Kingdom occupational exposure limit), the ability of plasma to detoxify chromium (VI) to chromium (III) before it reached the lymphocytes, or perhaps the insensitivity of the molecular techniques used. It is now important to test these and other such techniques on groups exposed to levels closer to the United Kingdom occupational exposure limit."
1260401,Gerin et al. 1993,Development and use of a welding process exposure matrix in a historical prospective study of lung cancer risk in European welders,"Development and use of a welding process exposure matrix (WPEM) for a study of the lung cancer risk in European welders was described. The WPEM was used in a study of lung cancer risk in 11,092 male welders employed by 135 companies in nine European countries. It was constructed for four subcohorts of welders, shipyard welders, mild steel welders, ever stainless steel welders, and stainless steel predominant welders, and for four types of welding fume components, total fume, total chromium (7440473), hexavalent-chromium (18540299) (Cr+6), and nickel (7440020) for the period 1940 to 1980. The data were obtained from individual occupational histories of the welders, company employment records and records of welding practice, published studies of welding exposures, and industrial hygiene measurements of welding fume exposures made in eight companies in the 1970s. The WPEMs provided exposure profiles for each welder that consisted of 13 combinations of welding process and metal welded. A statistically significant increase in lung cancer mortality was found for the entire cohort. The lung cancer risk tended to increase with time since first exposure for mild steel and stainless steel welders. The increase was significant for welders who welded primarily stainless steel. No association between duration of employment as a welder and lung cancer risk was seen in any subcohort. No association between risk and cumulative total fume or total chromium exposure was observed. A more detailed analysis of both subcohorts of stainless steel welders who were potentially exposed to Cr+6 and nickel did not reveal any dose response relations in lung cancer risk. The authors conclude that the WPEM is the first of its kind published for welding fumes. The lack of a dose response relationship for exposure to Cr+6 and nickel and lung cancer risk in the epidemiological study could reflect the effects of misclassification in the matrix or study design or the possibility that there is minimal risk related to chromium and nickel exposure in this group of workers.","Development and use of a welding process exposure matrix in a historical prospective study of lung cancer risk in European welders Abs: Development and use of a welding process exposure matrix (WPEM) for a study of the lung cancer risk in European welders was described. The WPEM was used in a study of lung cancer risk in 11,092 male welders employed by 135 companies in nine European countries. It was constructed for four subcohorts of welders, shipyard welders, mild steel welders, ever stainless steel welders, and stainless steel predominant welders, and for four types of welding fume components, total fume, total chromium (7440473), hexavalent-chromium (18540299) (Cr+6), and nickel (7440020) for the period 1940 to 1980. The data were obtained from individual occupational histories of the welders, company employment records and records of welding practice, published studies of welding exposures, and industrial hygiene measurements of welding fume exposures made in eight companies in the 1970s. The WPEMs provided exposure profiles for each welder that consisted of 13 combinations of welding process and metal welded. A statistically significant increase in lung cancer mortality was found for the entire cohort. The lung cancer risk tended to increase with time since first exposure for mild steel and stainless steel welders. The increase was significant for welders who welded primarily stainless steel. No association between duration of employment as a welder and lung cancer risk was seen in any subcohort. No association between risk and cumulative total fume or total chromium exposure was observed. A more detailed analysis of both subcohorts of stainless steel welders who were potentially exposed to Cr+6 and nickel did not reveal any dose response relations in lung cancer risk. The authors conclude that the WPEM is the first of its kind published for welding fumes. The lack of a dose response relationship for exposure to Cr+6 and nickel and lung cancer risk in the epidemiological study could reflect the effects of misclassification in the matrix or study design or the possibility that there is minimal risk related to chromium and nickel exposure in this group of workers."
1260400,Migliore et al. 1991,Micronucleated Lymphocytes in People Occupationally Exposed to Potential Environmental Contaminants: The Age Effect,"A report was presented which considered the analysis of the micronucleated (MN) frequency in peripheral blood lymphocytes of two groups of individuals working in the tannery industry. The groups consisted of subjects whose exposure to mutagenic or carcinogenic compounds was suspected. One group of subjects included workers employed in the drum workshop and potentially exposed to chromium (7440473) salts and dyes such as benzidine (92875) and o-toluidine (95534) derivatives. The other group included subjects employed in the finishing workshop and potentially exposed to solvents and pigments with a basis of chromium-VI. A clear increase was noted for MN cells as a function of age with a similar trend in both groups. Whether or not an individual smoked appeared to have no effect on the outcome of the studies. Chromosome analysis revealed a statistically significant increase in chromosomal aberrations in workers employed in the drum workshop and no difference in those employed in the finishing process, compared to their matched comparisons. The positive results mainly concerned increases in chromatid deletions.","Micronucleated Lymphocytes in People Occupationally Exposed to Potential Environmental Contaminants: The Age Effect Abs: A report was presented which considered the analysis of the micronucleated (MN) frequency in peripheral blood lymphocytes of two groups of individuals working in the tannery industry. The groups consisted of subjects whose exposure to mutagenic or carcinogenic compounds was suspected. One group of subjects included workers employed in the drum workshop and potentially exposed to chromium (7440473) salts and dyes such as benzidine (92875) and o-toluidine (95534) derivatives. The other group included subjects employed in the finishing workshop and potentially exposed to solvents and pigments with a basis of chromium-VI. A clear increase was noted for MN cells as a function of age with a similar trend in both groups. Whether or not an individual smoked appeared to have no effect on the outcome of the studies. Chromosome analysis revealed a statistically significant increase in chromosomal aberrations in workers employed in the drum workshop and no difference in those employed in the finishing process, compared to their matched comparisons. The positive results mainly concerned increases in chromatid deletions."
1260392,Hemminki and  Pershagen 1994,CANCER RISK OF AIR POLLUTION EPIDEMIOLOGICAL EVIDENCE,BIOSIS COPYRIGHT: BIOL ABS. RRM JOURNAL ARTICLE HUMAN LUNG CANCER ONCOGENESIS,CANCER RISK OF AIR POLLUTION EPIDEMIOLOGICAL EVIDENCE Abs: BIOSIS COPYRIGHT: BIOL ABS. RRM JOURNAL ARTICLE HUMAN LUNG CANCER ONCOGENESIS
1260390,Faux et al. 1994,Molecular epidemiological studies in workers exposed to chromium-containing compounds,BIOSIS COPYRIGHT: BIOL ABS. RRM RESEARCH ARTICLE HUMAN RAT GENOTOXICITY BRONCHOGENIC CARCINOMA 8-HYDROXY-2'-DEOXYGUANOSINE LYMPHOCYTE DNA STRAND BREAK CHROMIUMVI,Molecular epidemiological studies in workers exposed to chromium-containing compounds Abs: BIOSIS COPYRIGHT: BIOL ABS. RRM RESEARCH ARTICLE HUMAN RAT GENOTOXICITY BRONCHOGENIC CARCINOMA 8-HYDROXY-2'-DEOXYGUANOSINE LYMPHOCYTE DNA STRAND BREAK CHROMIUMVI
1260386,JP et al. 1992,Adverse pregnancy outcome and childhood malignancy with reference to paternal welding exposure,"BIOSIS COPYRIGHT: BIOL ABS. Welding may deteriorate spermatogenesis and increase reproductive failures. This study examines reproductive end points in a Danish cohort of 10 059 metalworkers who fathered 3569 children in 1973 through 1986. Occupational histories were gathered by postal questionnaires. Information on pregnancy outcomes and offspring was obtained by record linkage to medical registers. The occurrence of reduced birthweight, preterm delivery, infant mortality, and congenital malformation was not increased among children at risks from paternal welding exposure in comparison with children not at risk. The overall incidence of childhood malignancies among 23 264 children born in 1968 through 1986 with a total of 259 113 person-years of follow-up was equal to national rates (relative risk 0.97, 95% confidence interval 0.63-1.42). However, pregnancies preceding a birth at risk from paternal exposure to stainless steeless welding were more often terminated by spontaneous abortion (odds rati","Adverse pregnancy outcome and childhood malignancy with reference to paternal welding exposure Abs: BIOSIS COPYRIGHT: BIOL ABS. Welding may deteriorate spermatogenesis and increase reproductive failures. This study examines reproductive end points in a Danish cohort of 10 059 metalworkers who fathered 3569 children in 1973 through 1986. Occupational histories were gathered by postal questionnaires. Information on pregnancy outcomes and offspring was obtained by record linkage to medical registers. The occurrence of reduced birthweight, preterm delivery, infant mortality, and congenital malformation was not increased among children at risks from paternal welding exposure in comparison with children not at risk. The overall incidence of childhood malignancies among 23 264 children born in 1968 through 1986 with a total of 259 113 person-years of follow-up was equal to national rates (relative risk 0.97, 95% confidence interval 0.63-1.42). However, pregnancies preceding a birth at risk from paternal exposure to stainless steeless welding were more often terminated by spontaneous abortion (odds rati"
1260385,J-S and  Et 1990,Effects of chromium(VI)-polluted-well-water on inhabitant's health,"BIOSIS COPYRIGHT: BIOL ABS. The increase of Cr+8 in well water results from pollution by electroplating waste water. The average content of Cr+8 in water of the wells in the polluted area is as high as 1.68 mumol, obviously higher than that in the control area (P 0.05). The health condition of inhabitants is poor in the polluted area, with a higher incidence of such symptoms as dizziness, weariness, poor appetite, abdominal pain and dermatitis. The blood pressure of the inhabitants in the polluted area is generally lower than that of those in the control area. The chromium content in the urine of 36 cases in the polluted area is 0.12 mumol/L, which is much higher than that in the control area (P 0.05). This investigation indicates that long-term drinking of high-chromium content water is harmful to people's health.","Effects of chromium(VI)-polluted-well-water on inhabitant's health Abs: BIOSIS COPYRIGHT: BIOL ABS. The increase of Cr+8 in well water results from pollution by electroplating waste water. The average content of Cr+8 in water of the wells in the polluted area is as high as 1.68 mumol, obviously higher than that in the control area (P 0.05). The health condition of inhabitants is poor in the polluted area, with a higher incidence of such symptoms as dizziness, weariness, poor appetite, abdominal pain and dermatitis. The blood pressure of the inhabitants in the polluted area is generally lower than that of those in the control area. The chromium content in the urine of 36 cases in the polluted area is 0.12 mumol/L, which is much higher than that in the control area (P 0.05). This investigation indicates that long-term drinking of high-chromium content water is harmful to people's health."
1260384,Moulin et al. 1990,Mortality study among workers producing ferroalloys and stainless steel in France,"A mortality study was carried out among the workers of a plant that had produced ferrochromium and stainless steel, and was still producing stainless steel, in order to determine whether exposure to chromium compounds, to nickel compounds, and to polycyclic aromatic hydrocarbons (PAH) could result in a risk of lung cancer for the exposed workers. The cohort comprised 2269 men whose vital status were recorded between 1 January 1952 and 31 December 1982. The smoking habits of 67% of the cohort members were known from medical records. The observed numbers of deaths were compared with the expected ones based on national rates with adjustment for age, sex, and calendar time. A low mortality, achieving statistical significance, was found from all causes (observed = 137), standardised mortality ratio (SMR) = 0.82) and from benign respiratory diseases (observed = one, SMR = 0.15). With regard to mortality from lung cancer, a non-significant excess appeared in the whole cohort (o","Mortality study among workers producing ferroalloys and stainless steel in France Abs: A mortality study was carried out among the workers of a plant that had produced ferrochromium and stainless steel, and was still producing stainless steel, in order to determine whether exposure to chromium compounds, to nickel compounds, and to polycyclic aromatic hydrocarbons (PAH) could result in a risk of lung cancer for the exposed workers. The cohort comprised 2269 men whose vital status were recorded between 1 January 1952 and 31 December 1982. The smoking habits of 67% of the cohort members were known from medical records. The observed numbers of deaths were compared with the expected ones based on national rates with adjustment for age, sex, and calendar time. A low mortality, achieving statistical significance, was found from all causes (observed = 137), standardised mortality ratio (SMR) = 0.82) and from benign respiratory diseases (observed = one, SMR = 0.15). With regard to mortality from lung cancer, a non-significant excess appeared in the whole cohort (o"
1260383,Edling et al. 1986,CANCER MORTALITY AMONG LEATHER TANNERS,BIOSIS COPYRIGHT: BIOL ABS. RRM HUMAN STOMACH PANCREATIC CANCER SCANDINAVIA,CANCER MORTALITY AMONG LEATHER TANNERS Abs: BIOSIS COPYRIGHT: BIOL ABS. RRM HUMAN STOMACH PANCREATIC CANCER SCANDINAVIA
1260382,Aruldhas et al. 2004,Microcanalization in the epididymis to overcome ductal obstruction caused by chronic exposure to chromium - a study in the mature bonnet monkey (Macaca radiata Geoffroy),"In order to apprehend the toxic effects of chromium, an occupational/environmental pollutant, on the epididymis, adult bonnet monkeys were exposed to chromium (VI) in their drinking water at concentrations of 100, 200 and 400 p.p.m. for a chronic period of 180 days. At the end of the experimental period, testicles and segments of epididymis from control and treated monkeys were subjected to light microscopic (resin-embedded semi-thin sections) and transmission electron microscopic analyses. Among the various changes undergone by the epididymal epithelium, the present paper describes the origin of two different kinds of microcanals, probably caused by ductal obstruction. The first type of microcanal, which appears to provide passage for spermatozoa to bypass the obstructed main duct, is comparable with the one already reported in carbendazim-treated efferent ductules of the rat. The second type of microcanal, which is novel, consisted of a lumen in the epithelium enclosed by four to five cells, which are either modified basal cells, principal cells or a hitherto unknown cell type. This novel type of microcanal is suggested to be a device to entrap the spermatozoa which reach the core of the epithelium and may be a mechanism to prevent extravasation of sperm so as to avoid an autoimmune response of spermatic granuloma formation. Thus, the present study has shown that chronic exposure to chromium (VI) through drinking water can produce pathological manifestations in the epididymal epithelium but the epididymis, being a versatile organ, is capable of overcoming such adverse situations through novel devices.","Microcanalization in the epididymis to overcome ductal obstruction caused by chronic exposure to chromium - a study in the mature bonnet monkey (Macaca radiata Geoffroy) Abs: In order to apprehend the toxic effects of chromium, an occupational/environmental pollutant, on the epididymis, adult bonnet monkeys were exposed to chromium (VI) in their drinking water at concentrations of 100, 200 and 400 p.p.m. for a chronic period of 180 days. At the end of the experimental period, testicles and segments of epididymis from control and treated monkeys were subjected to light microscopic (resin-embedded semi-thin sections) and transmission electron microscopic analyses. Among the various changes undergone by the epididymal epithelium, the present paper describes the origin of two different kinds of microcanals, probably caused by ductal obstruction. The first type of microcanal, which appears to provide passage for spermatozoa to bypass the obstructed main duct, is comparable with the one already reported in carbendazim-treated efferent ductules of the rat. The second type of microcanal, which is novel, consisted of a lumen in the epithelium enclosed by four to five cells, which are either modified basal cells, principal cells or a hitherto unknown cell type. This novel type of microcanal is suggested to be a device to entrap the spermatozoa which reach the core of the epithelium and may be a mechanism to prevent extravasation of sperm so as to avoid an autoimmune response of spermatic granuloma formation. Thus, the present study has shown that chronic exposure to chromium (VI) through drinking water can produce pathological manifestations in the epididymal epithelium but the epididymis, being a versatile organ, is capable of overcoming such adverse situations through novel devices."
1260309,Parry et al. 2010,Thresholds for indirect DNA damage across cellular barriers for orthopaedic biomaterials,"Cobalt-chromium particles and ions can induce indirect DNA damage and chromosome aberrations in human cells on the other side of a cellular barrier in tissue culture. This occurs by intercellular signalling across the barrier. We now show that the threshold for this effect depends on the metal form and the particle composition. Ionic cobalt and chromium induced single strand breaks at concentrations equivalent to those found in the blood of patients with well functioning metal on metal hip prostheses. However, they only caused double strand breaks if the chromium was present as chromium (VI), and did not induce chromosome aberrations. Nanoparticles of cobalt-chromium alloy caused DNA double strand breaks and chromosome aberrations, of which the majority were tetraploidy. Ceramic nanoparticles induced only single strand breaks and/or alkaline labile sites when indirectly exposed to human fibroblasts. The assessment of reproductive risk from maternal exposure to biomaterials is not yet possible with epidemiology. Whilst the barrier model used here differs from the in vivo situation in several respects, it may be useful as a framework to evaluate biomaterial induced damage across physiological barriers.","Thresholds for indirect DNA damage across cellular barriers for orthopaedic biomaterials Abs: Cobalt-chromium particles and ions can induce indirect DNA damage and chromosome aberrations in human cells on the other side of a cellular barrier in tissue culture. This occurs by intercellular signalling across the barrier. We now show that the threshold for this effect depends on the metal form and the particle composition. Ionic cobalt and chromium induced single strand breaks at concentrations equivalent to those found in the blood of patients with well functioning metal on metal hip prostheses. However, they only caused double strand breaks if the chromium was present as chromium (VI), and did not induce chromosome aberrations. Nanoparticles of cobalt-chromium alloy caused DNA double strand breaks and chromosome aberrations, of which the majority were tetraploidy. Ceramic nanoparticles induced only single strand breaks and/or alkaline labile sites when indirectly exposed to human fibroblasts. The assessment of reproductive risk from maternal exposure to biomaterials is not yet possible with epidemiology. Whilst the barrier model used here differs from the in vivo situation in several respects, it may be useful as a framework to evaluate biomaterial induced damage across physiological barriers."
1260308,Shrivastava et al. 2007,Effect of pretreatment with chromium picolinate on haematological parameters during dengue virus infection in mice,"<strong>BACKGROUND &amp;#38; OBJECTIVE: </strong>Dengue virus (DV) has caused severe epidemics of dengue fever (DF) and dengue haemorrhagic fever (DHF) and is endemic all over India. We have earlier reported that exposure of mice to hexavalent chromium [Cr(VI)] compounds increased the severity of dengue virus infection. Trivalent chromium picolinate (CrP) is used worldwide as micronutrient and nutritional supplement. The present study was therefore, carried out to investigate the effects of CrP on various haematological parameters during DV infection of mice.<br /><br /><strong>METHODS: </strong>The Swiss Albino smice were inoculated with dengue virus (1000 LD50, intracerebrally) and fed with chromium picolinate (CrP) in drinking water (100 and 250 mg/l) for 24 wk. Peripheral blood leucocytes and other haematological parameters, and spleens were studied on days 4 and 8 after virus inoculations and the findings were compared with those given only CrP and the normal control age matched mice.<br /><br /><strong>RESULTS: </strong>CrP in drinking water for 24 wk had no significant effects on peripheral blood cells of mice. On the other hand, there was significant decrease in different haematological parameters following inoculation of normal mice with DV. In CrP fed mice the effects of DV infection were abolished on most of the haematological parameters.<br /><br /><strong>INTERPRETATION &amp;#38; CONCLUSION: </strong>The findings of present study showed that the adverse effects of DV infection, specially on platelets and leucocytes, were abrogated by pretreatment of mice with CrP. The therapeutic utility of CrP in viral infections including dengue needs to be studied in depth.","Effect of pretreatment with chromium picolinate on haematological parameters during dengue virus infection in mice Abs: <strong>BACKGROUND &amp;#38; OBJECTIVE: </strong>Dengue virus (DV) has caused severe epidemics of dengue fever (DF) and dengue haemorrhagic fever (DHF) and is endemic all over India. We have earlier reported that exposure of mice to hexavalent chromium [Cr(VI)] compounds increased the severity of dengue virus infection. Trivalent chromium picolinate (CrP) is used worldwide as micronutrient and nutritional supplement. The present study was therefore, carried out to investigate the effects of CrP on various haematological parameters during DV infection of mice.<br /><br /><strong>METHODS: </strong>The Swiss Albino smice were inoculated with dengue virus (1000 LD50, intracerebrally) and fed with chromium picolinate (CrP) in drinking water (100 and 250 mg/l) for 24 wk. Peripheral blood leucocytes and other haematological parameters, and spleens were studied on days 4 and 8 after virus inoculations and the findings were compared with those given only CrP and the normal control age matched mice.<br /><br /><strong>RESULTS: </strong>CrP in drinking water for 24 wk had no significant effects on peripheral blood cells of mice. On the other hand, there was significant decrease in different haematological parameters following inoculation of normal mice with DV. In CrP fed mice the effects of DV infection were abolished on most of the haematological parameters.<br /><br /><strong>INTERPRETATION &amp;#38; CONCLUSION: </strong>The findings of present study showed that the adverse effects of DV infection, specially on platelets and leucocytes, were abrogated by pretreatment of mice with CrP. The therapeutic utility of CrP in viral infections including dengue needs to be studied in depth."
1260307,Becker et al. 2006,Evaluation of potential toxicity and bioavailability of chromium in sediments associated with chromite ore processing residue,"Recent studies by researchers at the U.S. Environmental Protection Agency and U.S. Geological Survey have evaluated the toxicity of Cr in freshwater and marine sediments, primarily during laboratory studies in which clean sediments were spiked with Cr. Results of those studies showed that Cr is relatively insoluble and nontoxic when present in the trivalent form, Cr(III), rather than in the more soluble and more toxic hexavalent form, Cr(VI). The studies concluded that Cr toxicity should be low in sediments with measurable concentrations of acid-volatile sulfide (AVS), because AVS is formed only in anoxic sediments and Cr(VI) is thermodynamically unstable under such conditions. The present study evaluates the toxicity and bioavailability of Cr in sediments associated with chromite ore processing residue (COPR). Ten stations were sampled in the Hackensack River (NJ, USA) to represent a wide range of total Cr concentrations (199-3,970 mg/kg) with minimal interference from potentially toxic, co-occurring chemicals. Sediment toxicity was evaluated using two amphipod tests: The 10-d Ampelisca abdita test (survival as endpoint), and the 28-d Leptocheirus plumulosus test (survival and biomass as endpoints). Measurable concentrations of AVS were present at eight stations, and nearly all Cr was present as Cr(III). In addition, results of electron-microprobe analyses showed that most Cr was associated with phases in which Cr has limited bioavailability (i.e., chromite and iron oxide). Sediment toxicity showed no correlation with concentrations of total Cr, and the maximum no-effect concentration for total Cr was estimated as 1,310 mg/ kg. These results indicate that Cr can be present in sediments associated with COPR at highly elevated concentrations without causing sediment toxicity.","Evaluation of potential toxicity and bioavailability of chromium in sediments associated with chromite ore processing residue Abs: Recent studies by researchers at the U.S. Environmental Protection Agency and U.S. Geological Survey have evaluated the toxicity of Cr in freshwater and marine sediments, primarily during laboratory studies in which clean sediments were spiked with Cr. Results of those studies showed that Cr is relatively insoluble and nontoxic when present in the trivalent form, Cr(III), rather than in the more soluble and more toxic hexavalent form, Cr(VI). The studies concluded that Cr toxicity should be low in sediments with measurable concentrations of acid-volatile sulfide (AVS), because AVS is formed only in anoxic sediments and Cr(VI) is thermodynamically unstable under such conditions. The present study evaluates the toxicity and bioavailability of Cr in sediments associated with chromite ore processing residue (COPR). Ten stations were sampled in the Hackensack River (NJ, USA) to represent a wide range of total Cr concentrations (199-3,970 mg/kg) with minimal interference from potentially toxic, co-occurring chemicals. Sediment toxicity was evaluated using two amphipod tests: The 10-d Ampelisca abdita test (survival as endpoint), and the 28-d Leptocheirus plumulosus test (survival and biomass as endpoints). Measurable concentrations of AVS were present at eight stations, and nearly all Cr was present as Cr(III). In addition, results of electron-microprobe analyses showed that most Cr was associated with phases in which Cr has limited bioavailability (i.e., chromite and iron oxide). Sediment toxicity showed no correlation with concentrations of total Cr, and the maximum no-effect concentration for total Cr was estimated as 1,310 mg/ kg. These results indicate that Cr can be present in sediments associated with COPR at highly elevated concentrations without causing sediment toxicity."
1260306,El-Demerdash et al. 2006,Biochemical study on the protective role of folic acid in rabbits treated with chromium (VI),"Deleterious effects of chromium (VI) compounds are diversified affecting almost all the organ systems in a wide variety of animals. Therefore, the present study was carried out to determine the effectiveness of folic acid (FA) in alleviating the toxicity of chromium (VI) on certain biochemical parameters, lipid peroxidation, and enzyme activities of male New Zealand white rabbits. Six rabbits per group were assigned to one of four treatment groups: 0 mg FA and 0 mg Cr(VI)/kg BW (control); 8.3 microg FA/kg BW; 5 mg Cr(VI)/kg BW; 5 mg Cr(VI) plus 8.3 microg FA/kg BW, respectively. Rabbits were orally administered their respective doses every day for 10 weeks. Results obtained showed that Cr(VI) significantly (P &lt; 0.05) increased the levels of free radicals and the activity of glutathione S-transferase (GST), and decreased the content of sulfhydryl groups (SH groups) in liver, testes, brain, kidney, and lung. The activities of aspartate aminotransferase (AST), alanine aminotransferase (ALT), alkaline phosphatase (AlP), acid phosphatase (AcP), and lactate dehydrogenase (LDH) were significantly decreased in liver and testes due to Cr(VI) administration. Also, AlP and AcP activities were significantly decreased in kidney and lung. The activity of acetylcholinesterase (AChE) was significantly decreased in brain and plasma. Contrariwise, the activities of AST and ALT were significantly increased in plasma, while AlP and AcP decreased. Chromium (VI) treatment caused a significant decrease in plasma total protein (TP) and globulin, and increased total lipids (TL), cholesterol, glucose, urea, creatinine, and bilirubin concentrations. Folic acid alone significantly decreased the levels of free radicals in liver, brain, and kidney, and increased the content of SH-group. The activities of AST, ALT, and LDH in liver; AST, ALT, AlP, AcP, and LDH in testes; AcP in kidney; AlP and AcP in lung, and LDH in brain were significantly increased. Plasma TP and albumin were increased, while urea and creatinine were decreased. The presence of FA with Cr(VI) restored the changes in enzyme activities and biochemical parameters. In conclusion, folic acid could be effective in the protection of chromium-induced toxicity.","Biochemical study on the protective role of folic acid in rabbits treated with chromium (VI) Abs: Deleterious effects of chromium (VI) compounds are diversified affecting almost all the organ systems in a wide variety of animals. Therefore, the present study was carried out to determine the effectiveness of folic acid (FA) in alleviating the toxicity of chromium (VI) on certain biochemical parameters, lipid peroxidation, and enzyme activities of male New Zealand white rabbits. Six rabbits per group were assigned to one of four treatment groups: 0 mg FA and 0 mg Cr(VI)/kg BW (control); 8.3 microg FA/kg BW; 5 mg Cr(VI)/kg BW; 5 mg Cr(VI) plus 8.3 microg FA/kg BW, respectively. Rabbits were orally administered their respective doses every day for 10 weeks. Results obtained showed that Cr(VI) significantly (P &lt; 0.05) increased the levels of free radicals and the activity of glutathione S-transferase (GST), and decreased the content of sulfhydryl groups (SH groups) in liver, testes, brain, kidney, and lung. The activities of aspartate aminotransferase (AST), alanine aminotransferase (ALT), alkaline phosphatase (AlP), acid phosphatase (AcP), and lactate dehydrogenase (LDH) were significantly decreased in liver and testes due to Cr(VI) administration. Also, AlP and AcP activities were significantly decreased in kidney and lung. The activity of acetylcholinesterase (AChE) was significantly decreased in brain and plasma. Contrariwise, the activities of AST and ALT were significantly increased in plasma, while AlP and AcP decreased. Chromium (VI) treatment caused a significant decrease in plasma total protein (TP) and globulin, and increased total lipids (TL), cholesterol, glucose, urea, creatinine, and bilirubin concentrations. Folic acid alone significantly decreased the levels of free radicals in liver, brain, and kidney, and increased the content of SH-group. The activities of AST, ALT, and LDH in liver; AST, ALT, AlP, AcP, and LDH in testes; AcP in kidney; AlP and AcP in lung, and LDH in brain were significantly increased. Plasma TP and albumin were increased, while urea and creatinine were decreased. The presence of FA with Cr(VI) restored the changes in enzyme activities and biochemical parameters. In conclusion, folic acid could be effective in the protection of chromium-induced toxicity."
1260304,Das Neves et al. 2002,Comparative histological studies on liver of mice exposed to Cr(VI) and Cr(V) compounds,"Chromium toxicity is strongly dependent on its oxidation state. Cr(VI) is carcinogenic and mutagenic, although its in vivo and in vitro toxic effects are related to its intracellular fate. Inside the cells, Cr(VI) is rapidly reduced to stable Cr(III). As Cr(V) and Cr(IV) species have been reported to be formed in the Cr(VI) reduction pathways, Cr(VI)-induced damage is thought, at least in part, to arise from these hypervalent species. The study of Cr(VI) reduction mechanisms and the characterization of the effects of each reactive intermediate constitute important steps towards a better understanding of chromium toxicity. The purpose of this work is to enlarge the scope of Cr(VI)-induced alterations in mouse to other chromium species. Our studies have led to the in situ preparation of a new Cr(V) complex, 1Cr(V)-BT](2-), a stable compound at neutral pH, which mimics Cr(VI) reduction intermediates. The effect of Cr(V) on the histology of mice liver is assessed and compared with similar Cr(VI) assays. Liver toxicity was examined after single administrations of Cr(VI) or [Cr(V)-BT](2-) to mice. Both compounds produced reversible hepatic damage in a time-dependent manner. However, Cr(V) toxic effects have proved to be more rapid than with Cr(VI), permitting the role of Cr(VI) intermediates formed during intracellular chromium reduction to be highlighted.","Comparative histological studies on liver of mice exposed to Cr(VI) and Cr(V) compounds Abs: Chromium toxicity is strongly dependent on its oxidation state. Cr(VI) is carcinogenic and mutagenic, although its in vivo and in vitro toxic effects are related to its intracellular fate. Inside the cells, Cr(VI) is rapidly reduced to stable Cr(III). As Cr(V) and Cr(IV) species have been reported to be formed in the Cr(VI) reduction pathways, Cr(VI)-induced damage is thought, at least in part, to arise from these hypervalent species. The study of Cr(VI) reduction mechanisms and the characterization of the effects of each reactive intermediate constitute important steps towards a better understanding of chromium toxicity. The purpose of this work is to enlarge the scope of Cr(VI)-induced alterations in mouse to other chromium species. Our studies have led to the in situ preparation of a new Cr(V) complex, 1Cr(V)-BT](2-), a stable compound at neutral pH, which mimics Cr(VI) reduction intermediates. The effect of Cr(V) on the histology of mice liver is assessed and compared with similar Cr(VI) assays. Liver toxicity was examined after single administrations of Cr(VI) or [Cr(V)-BT](2-) to mice. Both compounds produced reversible hepatic damage in a time-dependent manner. However, Cr(V) toxic effects have proved to be more rapid than with Cr(VI), permitting the role of Cr(VI) intermediates formed during intracellular chromium reduction to be highlighted."
1260303,Hojo et al. 2000,In vivo singlet-oxygen generation in blood of chromium(VI)-treated mice: an electron spin resonance spin-trapping study,"Although it is assumed from in vitro experiments that the generation of reactive oxygen species such as the singlet oxygen (1O2), the hydroxyl radical, and the superoxide anion are responsible for chromium(VI) toxicity/carcinogenicity, no electron spin resonance (ESR) evidence for the generation of 1O2 in vivo has been reported. In this study, we have employed an ESR spin-trapping technique with 2,2,6,6-tetramethyl-4-piperidone (TMPD), a specific 1O2 trap, to detect 1O2 in blood. The ESR spectrum of the spin adduct observed in the blood of mice given 4.8 mmol Cr(VI)/kg body weight exhibited the 1:1:1 intensity pattern of three lines with a hyperfine coupling constant A(N) = 16.08 G and a g-value = 2.0066. The concentration of spin adduct detected in the blood was 1.46 microM (0.1% of total Cr concentration). The adduct production was inhibited by the addition of specific 1O2 scavengers such as 1,4-diazabicyclo[2.2.2]octane and sodium azide to the blood. The results indicate that the spin adduct is nitroxide produced by the reaction of 1O2 with TMPD. This is the first report of ESR evidence for the in vivo generation of 1O2 in mammals by Cr(VI).","In vivo singlet-oxygen generation in blood of chromium(VI)-treated mice: an electron spin resonance spin-trapping study Abs: Although it is assumed from in vitro experiments that the generation of reactive oxygen species such as the singlet oxygen (1O2), the hydroxyl radical, and the superoxide anion are responsible for chromium(VI) toxicity/carcinogenicity, no electron spin resonance (ESR) evidence for the generation of 1O2 in vivo has been reported. In this study, we have employed an ESR spin-trapping technique with 2,2,6,6-tetramethyl-4-piperidone (TMPD), a specific 1O2 trap, to detect 1O2 in blood. The ESR spectrum of the spin adduct observed in the blood of mice given 4.8 mmol Cr(VI)/kg body weight exhibited the 1:1:1 intensity pattern of three lines with a hyperfine coupling constant A(N) = 16.08 G and a g-value = 2.0066. The concentration of spin adduct detected in the blood was 1.46 microM (0.1% of total Cr concentration). The adduct production was inhibited by the addition of specific 1O2 scavengers such as 1,4-diazabicyclo[2.2.2]octane and sodium azide to the blood. The results indicate that the spin adduct is nitroxide produced by the reaction of 1O2 with TMPD. This is the first report of ESR evidence for the in vivo generation of 1O2 in mammals by Cr(VI)."
1260302,Qi et al. 2000,Increased levels of oxidatively damaged DNA induced by chromium(III) and H2O2: protection by melatonin and related molecules,"Chromium (Cr) compounds are known occupational and environmental carcinogens. This trace element is found in the workplace primarily in the valence forms Cr(III) and Cr(VI). Cr(III), which was thought originally to be relatively nontoxic, was recently found to be more reactive toward purified DNA than was chromium(VI). Herein, we examined the ability of Cr(III) to induce oxidative DNA damage by measuring the formation of 8-hydroxydeoxyguanosine (8-OH-dG) in purified calf thymus DNA incubated with CrCl3 plus H2O2. In this system we observed that the Cr(III)-induced formation of 8-OH-dG in isolated DNA was both dose- and time-dependent. When melatonin and related molecules, including 6-methoxy-1,2,3,4-tetrahydro-beta-carboline (pinoline), N-acetylserotonin, 6-hydroxymelatonin and indole-3-propionic acid, were co-incubated with CrCl3 plus H2O2, the accumulations of 8-OH-dG in DNA samples were markedly inhibited in a concentration-dependent manner. The concentrations of each indole required to reduce DNA damage by 50%, i.e. the IC50 values, were 0.48, 0.51, 0.88, 1.00 and 3.08 microM for pinoline, melatonin, N-acetylserotonin, 6-hydroxymelatonin and indole-3-propionic acid, respectively. These results suggest that one of the mechanisms by which Cr(III) may induce cancer is via Fenton-type reactions which generate the hydroxyl radical (*OH). The findings also indicate that the protective effects of melatonin and related molecules against Cr(III)-induced carcinogenesis relate to their direct *OH scavenging ability which thereby reduces the formation of the damaged DNA product, 8-OH-dG.","Increased levels of oxidatively damaged DNA induced by chromium(III) and H2O2: protection by melatonin and related molecules Abs: Chromium (Cr) compounds are known occupational and environmental carcinogens. This trace element is found in the workplace primarily in the valence forms Cr(III) and Cr(VI). Cr(III), which was thought originally to be relatively nontoxic, was recently found to be more reactive toward purified DNA than was chromium(VI). Herein, we examined the ability of Cr(III) to induce oxidative DNA damage by measuring the formation of 8-hydroxydeoxyguanosine (8-OH-dG) in purified calf thymus DNA incubated with CrCl3 plus H2O2. In this system we observed that the Cr(III)-induced formation of 8-OH-dG in isolated DNA was both dose- and time-dependent. When melatonin and related molecules, including 6-methoxy-1,2,3,4-tetrahydro-beta-carboline (pinoline), N-acetylserotonin, 6-hydroxymelatonin and indole-3-propionic acid, were co-incubated with CrCl3 plus H2O2, the accumulations of 8-OH-dG in DNA samples were markedly inhibited in a concentration-dependent manner. The concentrations of each indole required to reduce DNA damage by 50%, i.e. the IC50 values, were 0.48, 0.51, 0.88, 1.00 and 3.08 microM for pinoline, melatonin, N-acetylserotonin, 6-hydroxymelatonin and indole-3-propionic acid, respectively. These results suggest that one of the mechanisms by which Cr(III) may induce cancer is via Fenton-type reactions which generate the hydroxyl radical (*OH). The findings also indicate that the protective effects of melatonin and related molecules against Cr(III)-induced carcinogenesis relate to their direct *OH scavenging ability which thereby reduces the formation of the damaged DNA product, 8-OH-dG."
1260301,Kortenkamp et al. 1996,The reductive conversion of the carcinogen chromium (VI) and its role in the formation of DNA lesions,"The potential of Cr(VI), in combination with glutathione (GSH) or ascorbate (AsA) to induce apurinic/apyrimidinic sites (AP-sites) and single strand breaks (SSB) in isolated deoxyribonucleic acid (DNA) was investigated. The observation that both lesions were formed with equal probability and followed a similar time course suggests that they might arise from attack of a reactive species at C4' of the DNA sugar moeity. This idea is further substantiated by the finding that malondialdehyde-like products are released in chromate/GSH- and chromate/AsA-treated DNA. The generation of AP-sites and SSB was dependent on molecular oxygen and could be suppressed by the addition of catalase. Our results rule out hydroxyl radicals as the DNA damaging species. Furthermore, Cr(V), an intermediate formed during reaction with GSH or AsA, is not directly involved in the generation of DNA damage, unless activated by molecular oxygen. Our findings indicate that a superoxo- or peroxo-complex involving Cr(V) or Cr(IV) might be the species responsible for DNA damage. Evidence is presented that the DNA lesions arising from chromate/AsA have the potential to cause gene mutations.","The reductive conversion of the carcinogen chromium (VI) and its role in the formation of DNA lesions Abs: The potential of Cr(VI), in combination with glutathione (GSH) or ascorbate (AsA) to induce apurinic/apyrimidinic sites (AP-sites) and single strand breaks (SSB) in isolated deoxyribonucleic acid (DNA) was investigated. The observation that both lesions were formed with equal probability and followed a similar time course suggests that they might arise from attack of a reactive species at C4' of the DNA sugar moeity. This idea is further substantiated by the finding that malondialdehyde-like products are released in chromate/GSH- and chromate/AsA-treated DNA. The generation of AP-sites and SSB was dependent on molecular oxygen and could be suppressed by the addition of catalase. Our results rule out hydroxyl radicals as the DNA damaging species. Furthermore, Cr(V), an intermediate formed during reaction with GSH or AsA, is not directly involved in the generation of DNA damage, unless activated by molecular oxygen. Our findings indicate that a superoxo- or peroxo-complex involving Cr(V) or Cr(IV) might be the species responsible for DNA damage. Evidence is presented that the DNA lesions arising from chromate/AsA have the potential to cause gene mutations."
1260300,Schroeder and  Mitchener 1971,"Scandium, chromium(VI), gallium, yttrium, rhodium, palladium, indium in mice: effects on growth and life span",,"Scandium, chromium(VI), gallium, yttrium, rhodium, palladium, indium in mice: effects on growth and life span Abs: "
1258924,Messer and  Lucas 2002,Localization of metallic ions with gingival fibroblast subcellular fractions,"Nickel-based alloys have been in use since the 1930s; however, there are concerns regarding the release of metal ions (Be(+2), Cr(+6), Cr(+3), Ni(+2), Mo(+6)) from these alloys into surrounding tissues. Therefore, the objective of this study was to determine the cellular location and accumulation of ions using atomic absorption spectroscopy and correlate location with the cytotoxic, morphologic, and ultrastructural evaluations reported previously. Human gingival fibroblasts were exposed to the metal ions for 72 h. Controlled atomic absorption spectroscopy studies were used to determine the intracellular location of these ions reported as parts per million metal ions per milligram protein. Enzymatic markers were shown to correspond to the appropriate fraction indicating success in fractionation of the gingival fibroblasts. These results correspond with the cytotoxic, morphologic, and ultrastructural alterations reported previously for fibroblasts exposed to these ions. The highest concentration of beryllium ions occurred in the low-density molecule fraction, where lipofuscin granules were found, which has been shown to contain metal ions. The highest concentrations of hexavalent chromium ions occurred in the plasma membrane and nuclear fractions followed by the mitochondria fraction, which is supported by the ions' ability to oxidize to trivalent chromium accumulating at the membrane as well as the alterations in nuclear and mitochondrial function. For trivalent chromium, the highest concentrations occurred in the low-density molecule and the plasma membrane fractions, which correlates with the ions' inability to readily cross membranes. The highest concentration of molybdenum ions occurred in the plasma membrane fraction correlating with alterations in membrane morphology and increased numbers of myelin figures. The highest concentration of nickel ions was associated with the cytosol fraction where lipid droplets seen in the transmission electron micrographs were located. The current study demonstrates that a successful subcellular fractionation was obtained on gingival fibroblasts and that the location of metallic ions within the fractions correlated with cellular alterations reported previously.","Localization of metallic ions with gingival fibroblast subcellular fractions Abs: Nickel-based alloys have been in use since the 1930s; however, there are concerns regarding the release of metal ions (Be(+2), Cr(+6), Cr(+3), Ni(+2), Mo(+6)) from these alloys into surrounding tissues. Therefore, the objective of this study was to determine the cellular location and accumulation of ions using atomic absorption spectroscopy and correlate location with the cytotoxic, morphologic, and ultrastructural evaluations reported previously. Human gingival fibroblasts were exposed to the metal ions for 72 h. Controlled atomic absorption spectroscopy studies were used to determine the intracellular location of these ions reported as parts per million metal ions per milligram protein. Enzymatic markers were shown to correspond to the appropriate fraction indicating success in fractionation of the gingival fibroblasts. These results correspond with the cytotoxic, morphologic, and ultrastructural alterations reported previously for fibroblasts exposed to these ions. The highest concentration of beryllium ions occurred in the low-density molecule fraction, where lipofuscin granules were found, which has been shown to contain metal ions. The highest concentrations of hexavalent chromium ions occurred in the plasma membrane and nuclear fractions followed by the mitochondria fraction, which is supported by the ions' ability to oxidize to trivalent chromium accumulating at the membrane as well as the alterations in nuclear and mitochondrial function. For trivalent chromium, the highest concentrations occurred in the low-density molecule and the plasma membrane fractions, which correlates with the ions' inability to readily cross membranes. The highest concentration of molybdenum ions occurred in the plasma membrane fraction correlating with alterations in membrane morphology and increased numbers of myelin figures. The highest concentration of nickel ions was associated with the cytosol fraction where lipid droplets seen in the transmission electron micrographs were located. The current study demonstrates that a successful subcellular fractionation was obtained on gingival fibroblasts and that the location of metallic ions within the fractions correlated with cellular alterations reported previously."
1258255,Van Loon L et al. 1986,TEST BATTERY FOR METAL ALLERGY IN DENTISTRY,BIOSIS COPYRIGHT: BIOL ABS. RRM HUMAN ALLERGIC CONTACT STOMATITIS SKIN IRRITANT NICKEL PALLADIUM,TEST BATTERY FOR METAL ALLERGY IN DENTISTRY Abs: BIOSIS COPYRIGHT: BIOL ABS. RRM HUMAN ALLERGIC CONTACT STOMATITIS SKIN IRRITANT NICKEL PALLADIUM
1258253,Samitz et al. 1962,Inactivation of Chromium Ion in Allergic Eczematous Dermatitis,"Description of an anti chrome reagent based on the reduction of hexavalent chromium to the trivalent state with subsequent chelation, capable of inactivating patch test reactions in chromate sensitive patients. The reagent consists of sodium-pyrosulfite, tartaric-acid, glucose and ammonium-chloride. Current studies are being conducted in various industries to determine the usefulness of the reagent under actual working conditions.","Inactivation of Chromium Ion in Allergic Eczematous Dermatitis Abs: Description of an anti chrome reagent based on the reduction of hexavalent chromium to the trivalent state with subsequent chelation, capable of inactivating patch test reactions in chromate sensitive patients. The reagent consists of sodium-pyrosulfite, tartaric-acid, glucose and ammonium-chloride. Current studies are being conducted in various industries to determine the usefulness of the reagent under actual working conditions."
1258252,Roto et al. 1996,Addition of Ferrous Sulfate to Cement and Risk of Chromium Dermatitis among Construction Workers,"The effect of lowering the amount of water soluble hexavalent chromium (7440473) in cement on reducing the risk of chromium induced dermatitis among construction and prefabrication workers was studied in Finland. In 1987, 913 house construction workers and 707 prefabrication workers were interviewed and clinically examined for chromium dermatitis. Skin tests were performed on 105 workers with hand dermatitis. Of 16 who reported previous chromium allergy, 12 were retested. Among the workers tested in 1987, before the addition of ferrous-sulfate, the prevalence of chromium allergy was 7.7% among the 117 workers tested. All cases of chromium induced occupational dermatitis in the Finnish Register of Occupational Diseases between 1976 and 1992 were analyzed. Analysis of the register data indicated that the dermatitis associated with chromium allergy in these occupations had decreased since 1987. The authors conclude that adding ferrous-sulfate to cement may decrease the risk of chromium induced dermatitis among construction workers.","Addition of Ferrous Sulfate to Cement and Risk of Chromium Dermatitis among Construction Workers Abs: The effect of lowering the amount of water soluble hexavalent chromium (7440473) in cement on reducing the risk of chromium induced dermatitis among construction and prefabrication workers was studied in Finland. In 1987, 913 house construction workers and 707 prefabrication workers were interviewed and clinically examined for chromium dermatitis. Skin tests were performed on 105 workers with hand dermatitis. Of 16 who reported previous chromium allergy, 12 were retested. Among the workers tested in 1987, before the addition of ferrous-sulfate, the prevalence of chromium allergy was 7.7% among the 117 workers tested. All cases of chromium induced occupational dermatitis in the Finnish Register of Occupational Diseases between 1976 and 1992 were analyzed. Analysis of the register data indicated that the dermatitis associated with chromium allergy in these occupations had decreased since 1987. The authors conclude that adding ferrous-sulfate to cement may decrease the risk of chromium induced dermatitis among construction workers."
1258251,Mcmahon and  Chen 2005,Quantitative Assessment Of Dermal Sensitization Risk From Treated Articles: Hexavalent Chromium (CRVI) As A Case Study,"Reporting of the potential for a pesticide to cause allergic contact dermatitis (ACD)within EPA?s Office of Pesticide Programs (OPP) is typically communicated through precautionary labeling language for residential exposures, and through appropriate engineering controls or personal protective equipment in the occupational setting. In contrast to labeled pesticides, the marketing of treated articles (in which a registered pesticide is incorporated into the article to protect the integrity of the article itself ) bear no such labels, and thus the public may unknowingly be exposed to potential dermal sensitizers without a means of communication of risk. Recently, the OPP, through scientific peer review and discussion, developed the foundation of a scientifically sound approach to quantitative assessment of dermal sensitization risk using hexavalent chromium in treated wood as a case study. A level of concern of 0.009?g/cm2 for hexavalent chromium was determined by the OPP to be protective against induction of ACD in non-sensitized persons as well as protective against elicitation of ACD in previously sensitized persons. This case study provides a scientifically sound basis for future risk assessments involving quantitation of risk for ACD.","Quantitative Assessment Of Dermal Sensitization Risk From Treated Articles: Hexavalent Chromium (CRVI) As A Case Study Abs: Reporting of the potential for a pesticide to cause allergic contact dermatitis (ACD)within EPA?s Office of Pesticide Programs (OPP) is typically communicated through precautionary labeling language for residential exposures, and through appropriate engineering controls or personal protective equipment in the occupational setting. In contrast to labeled pesticides, the marketing of treated articles (in which a registered pesticide is incorporated into the article to protect the integrity of the article itself ) bear no such labels, and thus the public may unknowingly be exposed to potential dermal sensitizers without a means of communication of risk. Recently, the OPP, through scientific peer review and discussion, developed the foundation of a scientifically sound approach to quantitative assessment of dermal sensitization risk using hexavalent chromium in treated wood as a case study. A level of concern of 0.009?g/cm2 for hexavalent chromium was determined by the OPP to be protective against induction of ACD in non-sensitized persons as well as protective against elicitation of ACD in previously sensitized persons. This case study provides a scientifically sound basis for future risk assessments involving quantitation of risk for ACD."
1258250,Hjerpe 1986,Chromate dermatitis in an engine assembly department,"In an automotive engine assembly department, about 150 assemblers handle zinc-plated components that have been coated with hexavalent chromium (chromates). Protective gloves cannot be used, as fingertip feel is needed, and each assembler has almost continous contact with chromate-coated parts. This has caused 9 cases of chromate dermatitis since the coating was introduced in 1976. All the victims have suffered from the effects of steroid ointments as well as from relapses of eczema. Although so-called yellow chromation is clearly unsuitable for components that are manually handled, no alternative has been developed and its use is spreading.","Chromate dermatitis in an engine assembly department Abs: In an automotive engine assembly department, about 150 assemblers handle zinc-plated components that have been coated with hexavalent chromium (chromates). Protective gloves cannot be used, as fingertip feel is needed, and each assembler has almost continous contact with chromate-coated parts. This has caused 9 cases of chromate dermatitis since the coating was introduced in 1976. All the victims have suffered from the effects of steroid ointments as well as from relapses of eczema. Although so-called yellow chromation is clearly unsuitable for components that are manually handled, no alternative has been developed and its use is spreading."
1258248,Fleeger and  J-F 1990,A Case Study of Chromium VI-Induced Skin Ulcerations during a Porcelain Enamel Curing Operation,"An outbreak of hexavalent-chromium (18540299) (Cr+6) induced skin problems among ground coat line workers employed in a porcelain enamel curing operation was investigated. NIOSH was requested to perform a health hazard evaluation to investigate the source of skin problems in workers in the enamel department of a factory that manufactured gas and electric ranges (SIC-3631). Seven workers in the enamel department had reported skin ulcerations which were found to be consistent with Cr+6 exposure. Cr+6 concentrations ranging from 0.1 to 2.4 micrograms per milligram (microg/mg) were found in environmental samples obtained from hangers used to hold range parts as they passed through a curing oven. The coils of the curing oven were found to be defective permitting open flames to play on the hangers and parts. After the coils were repaired, a followup survey was performed. Seventy four of 78 workers in the enamel department completed a questionnaire to obtain information on skin problems, job history, and use of barrier creams and other skin protective measures. Ten workers, including the seven original cases, reported skin problems; eight were employed on the ground coat line. Environmental sampling showed concentrations of 0.3 to 4.4microg/mg Cr+6. The authors conclude that the skin problems of the workers were caused by defective curing oven coils. Open flames from the coils made Cr+6 more available to the hangers and created sharp edges on the hangers. The sharp edges cut the workers' hands enabling Cr+6 to penetrate into and under the skin. Recommendations include performing quarterly maintenance on the curing oven coils, requiring the enamel department workers to wear protective gloves and barrier creams, and cleaning the hangers as they exit the oven.","A Case Study of Chromium VI-Induced Skin Ulcerations during a Porcelain Enamel Curing Operation Abs: An outbreak of hexavalent-chromium (18540299) (Cr+6) induced skin problems among ground coat line workers employed in a porcelain enamel curing operation was investigated. NIOSH was requested to perform a health hazard evaluation to investigate the source of skin problems in workers in the enamel department of a factory that manufactured gas and electric ranges (SIC-3631). Seven workers in the enamel department had reported skin ulcerations which were found to be consistent with Cr+6 exposure. Cr+6 concentrations ranging from 0.1 to 2.4 micrograms per milligram (microg/mg) were found in environmental samples obtained from hangers used to hold range parts as they passed through a curing oven. The coils of the curing oven were found to be defective permitting open flames to play on the hangers and parts. After the coils were repaired, a followup survey was performed. Seventy four of 78 workers in the enamel department completed a questionnaire to obtain information on skin problems, job history, and use of barrier creams and other skin protective measures. Ten workers, including the seven original cases, reported skin problems; eight were employed on the ground coat line. Environmental sampling showed concentrations of 0.3 to 4.4microg/mg Cr+6. The authors conclude that the skin problems of the workers were caused by defective curing oven coils. Open flames from the coils made Cr+6 more available to the hangers and created sharp edges on the hangers. The sharp edges cut the workers' hands enabling Cr+6 to penetrate into and under the skin. Recommendations include performing quarterly maintenance on the curing oven coils, requiring the enamel department workers to wear protective gloves and barrier creams, and cleaning the hangers as they exit the oven."
1258247,Burrows 1987,Chromate Dermatitis,"A review was presented, primarily of more recent literature, on the dermatological toxicity of chromium (7440473). Topics included skin and nasal ulceration; chromium dermatitis, including trivalent chromium (16065831) versus hexavalent chromium (18540299); prognosis, in terms of persistence of patch tests and photosensitivity; causes of contact dermatitis, including cement, antirust agents, leather, printing, welding, bleaches and detergents, other causes, and oral chromate; and prevention of chromium dermatitis. It was found that although trivalent chromium appeared to be the immunogen concerned, positive patch tests could be produced more consistently at lower percentages with hexavalent chromium than with trivalent chromium and hexavalent chromium caused contact dermatitis more readily. Penetration of skin by the hexavalent form and conversion to the trivalent form were considered responsible for this. Consideration was given to the question of positive patch tests for chromium: whether there were false positives due to irritant patch tests or indications of true allergy. With very small quantities of chromium capable of sensitization, prevention of chromium dermatitis was considered to be difficult. Positive measures for prevention included replacement of hexavalent chromium by other compounds, reduction of hexavalent chromium to trivalent chromium in substances being handled, use of barrier creams for chromate sensitive patients, mechanization in the cement industry, maintaining low levels of atmospheric chromium, use of protective clothing, good housekeeping and general cleanliness, and good first aid facilities.","Chromate Dermatitis Abs: A review was presented, primarily of more recent literature, on the dermatological toxicity of chromium (7440473). Topics included skin and nasal ulceration; chromium dermatitis, including trivalent chromium (16065831) versus hexavalent chromium (18540299); prognosis, in terms of persistence of patch tests and photosensitivity; causes of contact dermatitis, including cement, antirust agents, leather, printing, welding, bleaches and detergents, other causes, and oral chromate; and prevention of chromium dermatitis. It was found that although trivalent chromium appeared to be the immunogen concerned, positive patch tests could be produced more consistently at lower percentages with hexavalent chromium than with trivalent chromium and hexavalent chromium caused contact dermatitis more readily. Penetration of skin by the hexavalent form and conversion to the trivalent form were considered responsible for this. Consideration was given to the question of positive patch tests for chromium: whether there were false positives due to irritant patch tests or indications of true allergy. With very small quantities of chromium capable of sensitization, prevention of chromium dermatitis was considered to be difficult. Positive measures for prevention included replacement of hexavalent chromium by other compounds, reduction of hexavalent chromium to trivalent chromium in substances being handled, use of barrier creams for chromate sensitive patients, mechanization in the cement industry, maintaining low levels of atmospheric chromium, use of protective clothing, good housekeeping and general cleanliness, and good first aid facilities."
1258244,Hansen et al. 2006,Cr(III) and Cr(VI) in leather and elicitation of eczema,"The aim of the present study was to investigate the relation between the content of Cr(VI) and soluble Cr(III) in leather and the ability of the leather to elicit eczema in chromium allergic patients. An array of chromium-tanned leather samples was analysed for the content of total Cr(VI) and soluble Cr(III) using the DIN 53314 and the DS/EN 420 methods. Subsequently, a group of 15 patients with a history of foot eczema and leather exposure was exposed to a selection of 14 chromium- and 1 vegetable-tanned leather sample on the upper back for 48 hr. In addition, one leather sample was used for a prolonged 14-day exposure study. In total, 4 of the 15 patients reacted to at least one leather sample, and 5 of the 14 leather samples elicited a reaction in at least 1 patient. The prolonged exposure study demonstrated that an extended exposure period may reveal allergenic potential of a leather sample not otherwise identified using an ordinary 48-hr exposure period. No relation was observed between the measured content of Cr(VI) and soluble Cr(III) in the leather and the elicitation of eczema. Thus, in order to evaluate the quality of chromium-tanned leather in relation to preventing allergic skin reactions, other more clinical relevant methods reflecting the actual bioavailable Cr(III) and Cr(VI) fractions should be developed.","Cr(III) and Cr(VI) in leather and elicitation of eczema Abs: The aim of the present study was to investigate the relation between the content of Cr(VI) and soluble Cr(III) in leather and the ability of the leather to elicit eczema in chromium allergic patients. An array of chromium-tanned leather samples was analysed for the content of total Cr(VI) and soluble Cr(III) using the DIN 53314 and the DS/EN 420 methods. Subsequently, a group of 15 patients with a history of foot eczema and leather exposure was exposed to a selection of 14 chromium- and 1 vegetable-tanned leather sample on the upper back for 48 hr. In addition, one leather sample was used for a prolonged 14-day exposure study. In total, 4 of the 15 patients reacted to at least one leather sample, and 5 of the 14 leather samples elicited a reaction in at least 1 patient. The prolonged exposure study demonstrated that an extended exposure period may reveal allergenic potential of a leather sample not otherwise identified using an ordinary 48-hr exposure period. No relation was observed between the measured content of Cr(VI) and soluble Cr(III) in the leather and the elicitation of eczema. Thus, in order to evaluate the quality of chromium-tanned leather in relation to preventing allergic skin reactions, other more clinical relevant methods reflecting the actual bioavailable Cr(III) and Cr(VI) fractions should be developed."
1258243,Boffetta et al. 2010,An estimate of cancers attributable to occupational exposures in France,"<strong>OBJECTIVE: </strong>To perform a quantitative estimate of the proportion of cancers attributable to occupational exposures in France in 2000.<br /><br /><strong>METHODS: </strong>Exposure data for established carcinogens were obtained from a 1994 survey and other sources. Relative risks for 23 exposure-cancer combinations were derived from meta-analyses and pooled analyses.<br /><br /><strong>RESULTS: </strong>A total of 4335 cases of cancer among men (2.7% of all cancers) and 403 cases among women (0.3% of all cancers) were attributed to occupational exposures. Asbestos, polycyclic aromatic hydrocarbons, and chromium VI were the main occupational carcinogens in men, and asbestos and involuntary smoking were the main carcinogens in women. Corresponding proportions for cancer deaths were 4.0% and 0.6% in men and women, respectively. Lung cancer represented 75% of deaths attributable to occupational exposures.<br /><br /><strong>CONCLUSION: </strong>Our estimates are comparable with those obtained for other countries in studies based on similar methodology.","An estimate of cancers attributable to occupational exposures in France Abs: <strong>OBJECTIVE: </strong>To perform a quantitative estimate of the proportion of cancers attributable to occupational exposures in France in 2000.<br /><br /><strong>METHODS: </strong>Exposure data for established carcinogens were obtained from a 1994 survey and other sources. Relative risks for 23 exposure-cancer combinations were derived from meta-analyses and pooled analyses.<br /><br /><strong>RESULTS: </strong>A total of 4335 cases of cancer among men (2.7% of all cancers) and 403 cases among women (0.3% of all cancers) were attributed to occupational exposures. Asbestos, polycyclic aromatic hydrocarbons, and chromium VI were the main occupational carcinogens in men, and asbestos and involuntary smoking were the main carcinogens in women. Corresponding proportions for cancer deaths were 4.0% and 0.6% in men and women, respectively. Lung cancer represented 75% of deaths attributable to occupational exposures.<br /><br /><strong>CONCLUSION: </strong>Our estimates are comparable with those obtained for other countries in studies based on similar methodology."
1258241,Cole and  Rodu 2005,Epidemiologic studies of chrome and cancer mortality: a series of meta-analyses,"We used 49 epidemiologic studies based on 84 papers published since 1950 to develop an array of meta-analyses relating exposure to chrome-six compounds with 10 causes of death. Most exposures occurred in occupational settings. Studies were assessed for quality, and for control of smoking or economic status if they related to lung or stomach cancer. There was no excess mortality from all causes combined among chrome-exposed persons. A minimal excess of cancer (SMR=112), overall, was due primarily to an excess of lung cancer (SMR=141) but the SMR was 112 among the better-quality, smoking-controlled studies. The overall SMR for stomach cancer was 113 but it was 82 among the studies that were controlled for economic status. Findings were unremarkable for the six other cancers evaluated: prostate, kidney, and central nervous system cancer and leukemia, Hodgkin's disease and other lymphatohematopoietic cancer. This series of meta-analyses indicates that chrome-six is a weak cause of lung cancer and is not a cause of any of the other seven forms of cancer evaluated.","Epidemiologic studies of chrome and cancer mortality: a series of meta-analyses Abs: We used 49 epidemiologic studies based on 84 papers published since 1950 to develop an array of meta-analyses relating exposure to chrome-six compounds with 10 causes of death. Most exposures occurred in occupational settings. Studies were assessed for quality, and for control of smoking or economic status if they related to lung or stomach cancer. There was no excess mortality from all causes combined among chrome-exposed persons. A minimal excess of cancer (SMR=112), overall, was due primarily to an excess of lung cancer (SMR=141) but the SMR was 112 among the better-quality, smoking-controlled studies. The overall SMR for stomach cancer was 113 but it was 82 among the studies that were controlled for economic status. Findings were unremarkable for the six other cancers evaluated: prostate, kidney, and central nervous system cancer and leukemia, Hodgkin's disease and other lymphatohematopoietic cancer. This series of meta-analyses indicates that chrome-six is a weak cause of lung cancer and is not a cause of any of the other seven forms of cancer evaluated."
1258238,Miksche and  Lewalter 1997,Health surveillance and biological effect monitoring for chromium-exposed workers,"Although workers may be exposed to chromium metal, Cr(III) compounds, and Cr(VI) compounds at the workplace, only Cr(VI) compounds are of primary concern in terms of possible health hazards. A special health surveillance program must focus on known health impairments and target organs. Medical surveillance in combination with biological monitoring can help to protect the workers' health. Biological monitoring for chromium exposure in urine, blood, and erythrocytes provides different types of information. Whereas chromium measurement in urine and whole blood or plasma is indicative of recent total chromium exposure, chromium detection in erythrocytes is attributable to Cr(VI) only and covers retrospectively a longer period of time due to the erythrocyte life span. Possibilities of biological effect monitoring are discussed.","Health surveillance and biological effect monitoring for chromium-exposed workers Abs: Although workers may be exposed to chromium metal, Cr(III) compounds, and Cr(VI) compounds at the workplace, only Cr(VI) compounds are of primary concern in terms of possible health hazards. A special health surveillance program must focus on known health impairments and target organs. Medical surveillance in combination with biological monitoring can help to protect the workers' health. Biological monitoring for chromium exposure in urine, blood, and erythrocytes provides different types of information. Whereas chromium measurement in urine and whole blood or plasma is indicative of recent total chromium exposure, chromium detection in erythrocytes is attributable to Cr(VI) only and covers retrospectively a longer period of time due to the erythrocyte life span. Possibilities of biological effect monitoring are discussed."
1258237,Milatou-Smith et al. 1997,Mortality among welders exposed to high and to low levels of hexavalent chromium and followed for more than 20 Years,"Hexavalent chromium particles are generated in the welding of stainless steel. A cohort consisting of 233 welders working on stainless steel and exposed to high levels of chromium was selected. According to an earlier survey, the hexavalent chromium exposures of such welders are often above 20 µg/m(3). Another cohort consisting of 208 railway track welders exposed to low levels of chromium was also selected. The participants of both cohorts had welded for at least five years between 1950 and 1965 and were followed for mortality until December 1992. Among the welders exposed to high levels of chromium, six deaths due to pulmonary tumors occurred. This number is higher than the two deaths that occurred among the welders exposed to low levels of chromium and the corresponding mortality of the general population, but not significantly higher. Thus, exposure to stainless steel welding fumes might increase the incidence of pulmonary tumors.","Mortality among welders exposed to high and to low levels of hexavalent chromium and followed for more than 20 Years Abs: Hexavalent chromium particles are generated in the welding of stainless steel. A cohort consisting of 233 welders working on stainless steel and exposed to high levels of chromium was selected. According to an earlier survey, the hexavalent chromium exposures of such welders are often above 20 µg/m(3). Another cohort consisting of 208 railway track welders exposed to low levels of chromium was also selected. The participants of both cohorts had welded for at least five years between 1950 and 1965 and were followed for mortality until December 1992. Among the welders exposed to high levels of chromium, six deaths due to pulmonary tumors occurred. This number is higher than the two deaths that occurred among the welders exposed to low levels of chromium and the corresponding mortality of the general population, but not significantly higher. Thus, exposure to stainless steel welding fumes might increase the incidence of pulmonary tumors."
1258233,Lee et al. ,Protective Effects of Pine Bark Extract on Hexavalent Chromium-Induced Dermatotoxicity in Rats,"The present study investigated the protective effects of pine bark extract (PBE) against hexavalent chromium [Cr(VI)]-induced dermatotoxicity in rats. Skin reactions were evaluated by visual inspection, histopathological changes and oxidative stress parameters. Topical application of Cr(VI) produced a significant increase in the incidence and severity of erythema and edema upon visual inspection. Histopathological examination showed moderate to severe necrosis and desquamation in the epidermis and inflammation and hemorrhage in the dermis. In addition, an increased malondialdehyde (MDA) concentration, and decreased glutathione (GSH), catalase, superoxide dismutase, glutathione-S-transferase (GST) and glutathione reductase of the skin were observed in the Cr(VI) group. On the contrary, concomitant administration with PBE significantly improved Cr(VI)-induced dermatotoxicity, evidenced by a decrease in the incidence and severity of skin irritation and histopathological lesions in a dose-dependent manner. Moreover, PBE treatment reduced MDA concentrations and increased catalase and GST activities in skin tissues, indicating that concomitant administration with PBE effectively prevents Cr(VI)-induced oxidative damage in rats. The results indicate that PBE has a protective effect against Cr(VI)-induced dermatotoxicity and is useful as a protective agent against various dermal lesions induced by oxidative stress. Copyright © 2012 John Wiley &amp; Sons, Ltd.","Protective Effects of Pine Bark Extract on Hexavalent Chromium-Induced Dermatotoxicity in Rats Abs: The present study investigated the protective effects of pine bark extract (PBE) against hexavalent chromium [Cr(VI)]-induced dermatotoxicity in rats. Skin reactions were evaluated by visual inspection, histopathological changes and oxidative stress parameters. Topical application of Cr(VI) produced a significant increase in the incidence and severity of erythema and edema upon visual inspection. Histopathological examination showed moderate to severe necrosis and desquamation in the epidermis and inflammation and hemorrhage in the dermis. In addition, an increased malondialdehyde (MDA) concentration, and decreased glutathione (GSH), catalase, superoxide dismutase, glutathione-S-transferase (GST) and glutathione reductase of the skin were observed in the Cr(VI) group. On the contrary, concomitant administration with PBE significantly improved Cr(VI)-induced dermatotoxicity, evidenced by a decrease in the incidence and severity of skin irritation and histopathological lesions in a dose-dependent manner. Moreover, PBE treatment reduced MDA concentrations and increased catalase and GST activities in skin tissues, indicating that concomitant administration with PBE effectively prevents Cr(VI)-induced oxidative damage in rats. The results indicate that PBE has a protective effect against Cr(VI)-induced dermatotoxicity and is useful as a protective agent against various dermal lesions induced by oxidative stress. Copyright © 2012 John Wiley &amp; Sons, Ltd."
1258231,Muttamara and  Leong 2004,"Health implication among occupational exposed workers in a chromium alloy factory, Thailand","This study was conducted to assess the occupational exposure and its health impact on the chromium alloy workers. Environmental and biological monitoring, noise and audiometry measurements were done to evaluate the exposure levels in the factory. A total of 112 non-smoking workers were monitored from July 2001 to August 2002. The results showed that most of the chromium and lead exposures in the factory were below the ACGIH-TWA of 50 microg/m3 for chromium(VI) and OSHA-PEL of 50 microg/m3 for lead. The highest chromium (7.25 +/- 0.16 microg/m3) and lead (14.50 +/- 0.29 microg/m3) concentrations were measured in the vibro room. The results indicated that elevated concentrations of chromium and lead were found in both blood and urine samples especially in those areas which were characterized by poor ventilation. The metal contents in blood and urine samples were significantly correlated with airborne metal concentrations in the factory. The result demonstrated that blood and urinary levels among workers were associated with increasing age and duration of exposure. The background noise level of the factory ranged from 67.6 to 89.2 dBA and was frequently higher than the threshold limit value for noise (90 dBA). According to the audiometric test, the exposed workers showed signs of noise-induced hearing loss. Noise at work continued to be an important factor to hearing loss among exposed workers. In our statistical analysis, a significant hearing loss was established on age effect and year of exposure among the workforce.","Health implication among occupational exposed workers in a chromium alloy factory, Thailand Abs: This study was conducted to assess the occupational exposure and its health impact on the chromium alloy workers. Environmental and biological monitoring, noise and audiometry measurements were done to evaluate the exposure levels in the factory. A total of 112 non-smoking workers were monitored from July 2001 to August 2002. The results showed that most of the chromium and lead exposures in the factory were below the ACGIH-TWA of 50 microg/m3 for chromium(VI) and OSHA-PEL of 50 microg/m3 for lead. The highest chromium (7.25 +/- 0.16 microg/m3) and lead (14.50 +/- 0.29 microg/m3) concentrations were measured in the vibro room. The results indicated that elevated concentrations of chromium and lead were found in both blood and urine samples especially in those areas which were characterized by poor ventilation. The metal contents in blood and urine samples were significantly correlated with airborne metal concentrations in the factory. The result demonstrated that blood and urinary levels among workers were associated with increasing age and duration of exposure. The background noise level of the factory ranged from 67.6 to 89.2 dBA and was frequently higher than the threshold limit value for noise (90 dBA). According to the audiometric test, the exposed workers showed signs of noise-induced hearing loss. Noise at work continued to be an important factor to hearing loss among exposed workers. In our statistical analysis, a significant hearing loss was established on age effect and year of exposure among the workforce."
1258230,Song et al. 2012,Effects of chronic chromium(vi) exposure on blood element homeostasis: an epidemiological study,"One hundred chromate production workers chronically exposed to low-level of hexavalent chromium [Cr(vi)] and eighty healthy individuals free from Cr exposure were recruited to the study. Personal sampling of airborne Cr was conducted and Cr content was quantified by Flame Atomic Absorption Spectrometry (FAAS). At the end of the sampling shift, blood samples were collected and element concentrations were measured by inductively coupled plasma mass spectrometry (ICP-MS) for Cr, Cd, Cu, Mo and Se and inductively coupled plasma atomic emission spectrometry (ICP-AES) for Ca, Fe, Mg and Zn. According to our results, 90% of the chromate production workers were exposed to airborne Cr in a concentration lower than 50 ?g m(-3), which is the threshold limit value recommended by the American Conference of Governmental Industrial Hygienists and Chinese Ministry of Health. After Cr(vi) exposure, a significant increase in blood Cr, Cd, Fe, Mg, Mo, Se and Zn concentrations was observed, as well as a significant decrease in Ca concentration. A decrease in blood Cu was only observed among female workers. Blood Cr concentrations of the exposed workers (median = 15.68 ng mL(-1)) was four times higher than that of the controls (median = 3.03 ng mL(-1)), and significantly correlated with airborne Cr (r = 0.568, P<0.001). In addition, the inter-element correlations exhibited significant differences between the two groups. Our findings of the related health effects suggested that the underlying mechanisms of chronic Cr(vi) exposure on blood element homeostasis might be partly explained by oxidative stress in the body, dysfunction of Fe metabolism and renal injury.","Effects of chronic chromium(vi) exposure on blood element homeostasis: an epidemiological study Abs: One hundred chromate production workers chronically exposed to low-level of hexavalent chromium [Cr(vi)] and eighty healthy individuals free from Cr exposure were recruited to the study. Personal sampling of airborne Cr was conducted and Cr content was quantified by Flame Atomic Absorption Spectrometry (FAAS). At the end of the sampling shift, blood samples were collected and element concentrations were measured by inductively coupled plasma mass spectrometry (ICP-MS) for Cr, Cd, Cu, Mo and Se and inductively coupled plasma atomic emission spectrometry (ICP-AES) for Ca, Fe, Mg and Zn. According to our results, 90% of the chromate production workers were exposed to airborne Cr in a concentration lower than 50 ?g m(-3), which is the threshold limit value recommended by the American Conference of Governmental Industrial Hygienists and Chinese Ministry of Health. After Cr(vi) exposure, a significant increase in blood Cr, Cd, Fe, Mg, Mo, Se and Zn concentrations was observed, as well as a significant decrease in Ca concentration. A decrease in blood Cu was only observed among female workers. Blood Cr concentrations of the exposed workers (median = 15.68 ng mL(-1)) was four times higher than that of the controls (median = 3.03 ng mL(-1)), and significantly correlated with airborne Cr (r = 0.568, P<0.001). In addition, the inter-element correlations exhibited significant differences between the two groups. Our findings of the related health effects suggested that the underlying mechanisms of chronic Cr(vi) exposure on blood element homeostasis might be partly explained by oxidative stress in the body, dysfunction of Fe metabolism and renal injury."
1258229,Wang et al. 2012,Oxidative DNA damage and global DNA hypomethylation are related to folate deficiency in chromate manufacturing workers,"Exposure to hexavalent chromium [Cr (VI)] can cause DNA damage, genetic instability and increase the risk of cancer development. Folate deficiency affects DNA methylation and reduces the stability of the genetic material. However, the correlation between folate deficiency and DNA damage has never been clearly elucidated in chromate workers. In this study, we recruited one hundred and fifteen workers from chromate producing facilities as testing subjects and sixty local residents without chromium exposure history served as controls. The results showed an evident accumulation of Cr in peripheral red blood cells accompanied by a significantly decreased serum folate in chromate exposed workers. The decreased serum folate was associated with an increased urinary 8-hydroxy-2'-deoxyguanosine, DNA strand breaks and global DNA hypomethylation. These findings suggest that chronic occupational chromate exposure could induce folate depletion, which may further promote DNA damages and global DNA hypomethylation. Adequate folate supplement may provide benefit to chromate sufferers in stabilization of genetic material and reduce the risk of cancer development.","Oxidative DNA damage and global DNA hypomethylation are related to folate deficiency in chromate manufacturing workers Abs: Exposure to hexavalent chromium [Cr (VI)] can cause DNA damage, genetic instability and increase the risk of cancer development. Folate deficiency affects DNA methylation and reduces the stability of the genetic material. However, the correlation between folate deficiency and DNA damage has never been clearly elucidated in chromate workers. In this study, we recruited one hundred and fifteen workers from chromate producing facilities as testing subjects and sixty local residents without chromium exposure history served as controls. The results showed an evident accumulation of Cr in peripheral red blood cells accompanied by a significantly decreased serum folate in chromate exposed workers. The decreased serum folate was associated with an increased urinary 8-hydroxy-2'-deoxyguanosine, DNA strand breaks and global DNA hypomethylation. These findings suggest that chronic occupational chromate exposure could induce folate depletion, which may further promote DNA damages and global DNA hypomethylation. Adequate folate supplement may provide benefit to chromate sufferers in stabilization of genetic material and reduce the risk of cancer development."
1258228,Wójcik and  Luterek 2003,Analysis of occupational risk due to exposure to carcinogenic factors in the work environment of a chemical plant,"The evaluation of exposure to some carcinogenic chemicals and seemingly carcinogenic chemicals, e.g. mist of sulphuric acid, benzene, chromium (VI) and formaldehyde among employees of some departments of a chemical plant was carried out. The study was carried out in the years 1999--2002. The analysis of concentration of the studied substances revealed the highest risk of exposure in the Cyclohexanon Department and The Maintenance Services Department in Caprolactam department. No direct relationship between the exposure to the studied chemicals and the development of cancer in the working population was found.","Analysis of occupational risk due to exposure to carcinogenic factors in the work environment of a chemical plant Abs: The evaluation of exposure to some carcinogenic chemicals and seemingly carcinogenic chemicals, e.g. mist of sulphuric acid, benzene, chromium (VI) and formaldehyde among employees of some departments of a chemical plant was carried out. The study was carried out in the years 1999--2002. The analysis of concentration of the studied substances revealed the highest risk of exposure in the Cyclohexanon Department and The Maintenance Services Department in Caprolactam department. No direct relationship between the exposure to the studied chemicals and the development of cancer in the working population was found."
1258218,Pokrovskaya and  Shabynina 1974,Epidemiological Data on Malignant Neoplasms When Working with Various Chromium Compounds,"An epidemiological study was conducted to examine the death rate from cancer in workers at one of the largest chromium (7440473) (Cr) mines in the Soviet Union. Dust concentrations and Cr concentrations were determined in the air of various workplaces. Death rates from cancer were determined from death certificates and compared with death rates for populations of nearby cities not exposed to carcinogens at work. The death rate from cancer among workers in the mines and Cr compound factory was significantly higher than the death rate among the urban population; death rates were 2.2 times higher in male workers and 1.8 times higher in female workers than in the urban population. In the shops, the death rates from cancer were even higher than in the mine. Hexavalent-chromium concentrations in the workplaces varied from 0.03 to 12.0 milligrams per cubic meter (mg/m3), compared with a maximum allowable concentration of 0.01mg/m3. The death rate from cancer in all work areas was 3.3 times higher among the workers than among the inhabitants of the city. Lung cancer deaths were 16 times higher and cancer of the esophagus was 7.7 times higher. The authors conclude that carcinogenic hazards exist in areas where Cr is present in either hexavalent or trivalent forms. The high cancer death rate among Cr workers confirms the role of working conditions in the development of disease and the need for rigorous observation of sanitary standards and hygienic requirements in creating safe working conditions. (Russian)","Epidemiological Data on Malignant Neoplasms When Working with Various Chromium Compounds Abs: An epidemiological study was conducted to examine the death rate from cancer in workers at one of the largest chromium (7440473) (Cr) mines in the Soviet Union. Dust concentrations and Cr concentrations were determined in the air of various workplaces. Death rates from cancer were determined from death certificates and compared with death rates for populations of nearby cities not exposed to carcinogens at work. The death rate from cancer among workers in the mines and Cr compound factory was significantly higher than the death rate among the urban population; death rates were 2.2 times higher in male workers and 1.8 times higher in female workers than in the urban population. In the shops, the death rates from cancer were even higher than in the mine. Hexavalent-chromium concentrations in the workplaces varied from 0.03 to 12.0 milligrams per cubic meter (mg/m3), compared with a maximum allowable concentration of 0.01mg/m3. The death rate from cancer in all work areas was 3.3 times higher among the workers than among the inhabitants of the city. Lung cancer deaths were 16 times higher and cancer of the esophagus was 7.7 times higher. The authors conclude that carcinogenic hazards exist in areas where Cr is present in either hexavalent or trivalent forms. The high cancer death rate among Cr workers confirms the role of working conditions in the development of disease and the need for rigorous observation of sanitary standards and hygienic requirements in creating safe working conditions. (Russian)"
1258216,Husgafvel-Pursiainen et al. 1982,A chromosome study among stainless steel welders,"The mutagenicity of welding fumes generated by manual metal arc (MMA) welding of stainless steel (SS) has been shown in several experimental in vitro systems. No data are available on possible chromosome damage among MMA/SS welders. In the present study, structural chromosome aberrations and sister chromatid exchanges (SCEs) were studied in peripheral blood lymphocytes of 23 welders and 22 control subjects. No significant differences in the frequency of chromosome aberrations or SCEs were detected between the two groups. Smokers, both welders and controls, showed a significantly higher SCE rate than non-smokers.","A chromosome study among stainless steel welders Abs: The mutagenicity of welding fumes generated by manual metal arc (MMA) welding of stainless steel (SS) has been shown in several experimental in vitro systems. No data are available on possible chromosome damage among MMA/SS welders. In the present study, structural chromosome aberrations and sister chromatid exchanges (SCEs) were studied in peripheral blood lymphocytes of 23 welders and 22 control subjects. No significant differences in the frequency of chromosome aberrations or SCEs were detected between the two groups. Smokers, both welders and controls, showed a significantly higher SCE rate than non-smokers."
1258215,Dueva et al. 1987,Immunological aspects of the body response of workers to industrial allergens,The results of an immunological study of 222 workers exposed to chemical allergens under various industrial conditions and 213 patients with occupational respiratory and skin allergies are presented along with the results of model studies of 275 guinea-pigs exposed to a wide range of trivalent and hexavalent chromium and formaldehyde doses. The allergic pathology phenotype is fundamentally different from all healthy body responses to industrial allergens. Disruption of cellular regulatory mechanisms and inhibition of lymph cell response to mitogenic stimuli identified at the initial stages of the allergic process should be considered as one of the basic risk criteria for the development of occupational allergic disease.,Immunological aspects of the body response of workers to industrial allergens Abs: The results of an immunological study of 222 workers exposed to chemical allergens under various industrial conditions and 213 patients with occupational respiratory and skin allergies are presented along with the results of model studies of 275 guinea-pigs exposed to a wide range of trivalent and hexavalent chromium and formaldehyde doses. The allergic pathology phenotype is fundamentally different from all healthy body responses to industrial allergens. Disruption of cellular regulatory mechanisms and inhibition of lymph cell response to mitogenic stimuli identified at the initial stages of the allergic process should be considered as one of the basic risk criteria for the development of occupational allergic disease.
1258210,Moulin et al. 1993,A mortality study among mild steel and stainless steel welders,"A mortality study was carried out in conjunction with the European mortality study among welders coordinated by the International Agency for Research on Cancer (IARC). The study was aimed at assessing risks for lung cancer in relation to exposure to asbestos, welding fumes containing chromium and nickel, and tobacco smoke. The study included a cohort of 2721 welders and an internal comparison group of 6683 manual workers employed in 13 factories in France. The mortality of the two cohorts was studied from 1975 to 1988 by the historical prospective method. Job histories of welders were traced including welding processes used, metals welded, and proportion of worktime spent in welding. Data on smoking habits were collected from medical records. The observed number of deaths were compared with those expected (standardised mortality ratio (SMR)) based on national rates with adjustments for age, sex, and calendar time. The smoking habits of 87% of the whole study population were known. The distribution of welders and controls according to smoking was not statistically different. The overall mortality was slightly higher for welders (SMR = 1.02, 95% confidence interval (95% CI) 0.89-1.18) than for controls (SMR = 0.91, 95% CI 0.84-0.99). For lung cancer, the SMR was 1.24 (95% CI 0.75-1.94) for welders, whereas the corresponding value was lower for controls (SMR = 0.94, 95% CI 0.68-1.26). The SMR for lung cancer was 1.59 among non-shipyard mild steel welders (95% CI 0.73-3.02). This contrasted with the results for all stainless steel welders (SMR = 0.92, 95% CI 0.19-2.69), and for stainless steel welders predominantly exposed to chromium VI (SMR = 1.03, 95% CI 0.12-3.71). Moreover, SMRs for lung cancer for mild steel welders tended to increase with duration of exposure and time since first exposure, leading to significant excesses for duration &gt; or = 20 years and latency &gt; or = 20 years. Such a pattern was not found for stainless steel welders.","A mortality study among mild steel and stainless steel welders Abs: A mortality study was carried out in conjunction with the European mortality study among welders coordinated by the International Agency for Research on Cancer (IARC). The study was aimed at assessing risks for lung cancer in relation to exposure to asbestos, welding fumes containing chromium and nickel, and tobacco smoke. The study included a cohort of 2721 welders and an internal comparison group of 6683 manual workers employed in 13 factories in France. The mortality of the two cohorts was studied from 1975 to 1988 by the historical prospective method. Job histories of welders were traced including welding processes used, metals welded, and proportion of worktime spent in welding. Data on smoking habits were collected from medical records. The observed number of deaths were compared with those expected (standardised mortality ratio (SMR)) based on national rates with adjustments for age, sex, and calendar time. The smoking habits of 87% of the whole study population were known. The distribution of welders and controls according to smoking was not statistically different. The overall mortality was slightly higher for welders (SMR = 1.02, 95% confidence interval (95% CI) 0.89-1.18) than for controls (SMR = 0.91, 95% CI 0.84-0.99). For lung cancer, the SMR was 1.24 (95% CI 0.75-1.94) for welders, whereas the corresponding value was lower for controls (SMR = 0.94, 95% CI 0.68-1.26). The SMR for lung cancer was 1.59 among non-shipyard mild steel welders (95% CI 0.73-3.02). This contrasted with the results for all stainless steel welders (SMR = 0.92, 95% CI 0.19-2.69), and for stainless steel welders predominantly exposed to chromium VI (SMR = 1.03, 95% CI 0.12-3.71). Moreover, SMRs for lung cancer for mild steel welders tended to increase with duration of exposure and time since first exposure, leading to significant excesses for duration &gt; or = 20 years and latency &gt; or = 20 years. Such a pattern was not found for stainless steel welders."
1258204,Simonato et al. 1991,"A historical prospective study of European stainless steel, mild steel, and shipyard welders","A multicentre cohort of 11,092 male welders from 135 companies located in nine European countries has been assembled with the aim of investigating the relation of potential cancer risk, lung cancer in particular, with occupational exposure. The observation period and the criteria for inclusion of welders varied from country to country. Follow up was successful for 96.9% of the cohort and observed numbers of deaths (and for some countries incident cancer cases) were compared with expected numbers calculated from national reference rates. Mortality and cancer incidence ratios were analysed by cause category, time since first exposure, duration of employment, and estimated cumulative dose to total fumes, chromium (Cr), Cr VI, and nickel (Ni). Overall a statistically significant excess was reported for mortality from lung cancer (116 observed v 86.81 expected deaths, SMR = 134). When analysed by type of welding an increasing pattern with time since first exposure was present for both mild steel and stainless steel welders, which was more noticeable for the subcohort of predominantly stainless steel welders. No clear relation was apparent between mortality from lung cancer and duration of exposure to or estimated cumulative dose of Ni or Cr. Whereas the patterns of lung cancer mortality in these results suggest that the risk of lung cancer is higher for stainless steel than mild steel welders the different level of risk for these two categories of welding exposure cannot be quantified with precision. The report of five deaths from pleural mesothelioma unrelated to the type of welding draws attention to the risk of exposure to asbestos in welding activities.","A historical prospective study of European stainless steel, mild steel, and shipyard welders Abs: A multicentre cohort of 11,092 male welders from 135 companies located in nine European countries has been assembled with the aim of investigating the relation of potential cancer risk, lung cancer in particular, with occupational exposure. The observation period and the criteria for inclusion of welders varied from country to country. Follow up was successful for 96.9% of the cohort and observed numbers of deaths (and for some countries incident cancer cases) were compared with expected numbers calculated from national reference rates. Mortality and cancer incidence ratios were analysed by cause category, time since first exposure, duration of employment, and estimated cumulative dose to total fumes, chromium (Cr), Cr VI, and nickel (Ni). Overall a statistically significant excess was reported for mortality from lung cancer (116 observed v 86.81 expected deaths, SMR = 134). When analysed by type of welding an increasing pattern with time since first exposure was present for both mild steel and stainless steel welders, which was more noticeable for the subcohort of predominantly stainless steel welders. No clear relation was apparent between mortality from lung cancer and duration of exposure to or estimated cumulative dose of Ni or Cr. Whereas the patterns of lung cancer mortality in these results suggest that the risk of lung cancer is higher for stainless steel than mild steel welders the different level of risk for these two categories of welding exposure cannot be quantified with precision. The report of five deaths from pleural mesothelioma unrelated to the type of welding draws attention to the risk of exposure to asbestos in welding activities."
1256740,Chervona and  Costa ,"The control of histone methylation and gene expression by oxidative stress, hypoxia and metals","The harmful consequences of carcinogenic metals, such as nickel, arsenic and chromium, are thought to be in part due to their ability to induce oxidative stress. The ubiquity of oxidative stress in biological systems has made it a fairly obvious culprit in causing cellular damage and/or development of disease. However, the full extent of oxidative stress-induced damage is not limited to its direct effects on cellular components, such as lipids, proteins and DNA, but may extend to its ability to alter gene expression. Gene expression regulation is an important component of cellular and/or tissue homeostasis, and its alteration can have detrimental consequences. Therefore, a growing amount of interest is being paid to understanding how oxidative stress can influence gene expression. Oxidative stress-induced epigenetic dysregulation in the form of post-translational histone modifications, in particular, is a popular topic of research. This review will therefore primarily focus on discussing the role of oxidative stress and hypoxia on histone methylation and/or gene expression alterations. The sources of oxidative stress discussed here are carcinogenic metals, such as, nickel, arsenic and chromium.","The control of histone methylation and gene expression by oxidative stress, hypoxia and metals Abs: The harmful consequences of carcinogenic metals, such as nickel, arsenic and chromium, are thought to be in part due to their ability to induce oxidative stress. The ubiquity of oxidative stress in biological systems has made it a fairly obvious culprit in causing cellular damage and/or development of disease. However, the full extent of oxidative stress-induced damage is not limited to its direct effects on cellular components, such as lipids, proteins and DNA, but may extend to its ability to alter gene expression. Gene expression regulation is an important component of cellular and/or tissue homeostasis, and its alteration can have detrimental consequences. Therefore, a growing amount of interest is being paid to understanding how oxidative stress can influence gene expression. Oxidative stress-induced epigenetic dysregulation in the form of post-translational histone modifications, in particular, is a popular topic of research. This review will therefore primarily focus on discussing the role of oxidative stress and hypoxia on histone methylation and/or gene expression alterations. The sources of oxidative stress discussed here are carcinogenic metals, such as, nickel, arsenic and chromium."
1255995,Torkmahalleh et al. 2012,The Impact of Deliquescence and pH on Cr Speciation in Ambient PM Samples,,The Impact of Deliquescence and pH on Cr Speciation in Ambient PM Samples Abs: 
1255505,Dsikowitzky et al. ,"Assessment of heavy metals in water samples and tissues of edible fish species from Awassa and Koka Rift Valley Lakes, Ethiopia","The Ethiopian Rift Valley Lakes host populations of edible fish species including Oreochromis niloticus, Labeobarbus intermedius and Clarias gariepinus, which are harvested also in other tropical countries. We investigated the occurrence of six heavy metals in tissues of these fish species as well as in the waters of Lake Koka and Lake Awassa. Both lakes are affected by industrial effluents in their catchments, making them ideal study sites. Mercury concentrations were very low in the water samples, but concentrations in the fish samples were relatively high, suggesting a particularly high bioaccumulation tendency as compared with the other investigated metals. Mercury was preferentially accumulated in the fish liver or muscle. It was the only metal with species-specific accumulation with highest levels found in the predatory species L. intermedius. Lower mercury concentrations in O. niloticus could be attributed to the lower trophic level, whereas mercury values in the predatory C. gariepinus were unexpectedly low. This probably relates to the high growth rate of this species resulting in biodilution of mercury. Accumulation of lead, selenium, chromium, arsenic and cadmium did not differ between species, indicating that these elements are not biomagnified in the food chain. Values of cadmium, selenium and arsenic were highest in fish livers, while lead and chromium levels were highest in the gills, which could be related to the uptake pathway. A significant impact of the industrial discharges on the occurrence of metals in the lakes could not be detected, and the respective concentrations in fish do not pose a public health hazard.","Assessment of heavy metals in water samples and tissues of edible fish species from Awassa and Koka Rift Valley Lakes, Ethiopia Abs: The Ethiopian Rift Valley Lakes host populations of edible fish species including Oreochromis niloticus, Labeobarbus intermedius and Clarias gariepinus, which are harvested also in other tropical countries. We investigated the occurrence of six heavy metals in tissues of these fish species as well as in the waters of Lake Koka and Lake Awassa. Both lakes are affected by industrial effluents in their catchments, making them ideal study sites. Mercury concentrations were very low in the water samples, but concentrations in the fish samples were relatively high, suggesting a particularly high bioaccumulation tendency as compared with the other investigated metals. Mercury was preferentially accumulated in the fish liver or muscle. It was the only metal with species-specific accumulation with highest levels found in the predatory species L. intermedius. Lower mercury concentrations in O. niloticus could be attributed to the lower trophic level, whereas mercury values in the predatory C. gariepinus were unexpectedly low. This probably relates to the high growth rate of this species resulting in biodilution of mercury. Accumulation of lead, selenium, chromium, arsenic and cadmium did not differ between species, indicating that these elements are not biomagnified in the food chain. Values of cadmium, selenium and arsenic were highest in fish livers, while lead and chromium levels were highest in the gills, which could be related to the uptake pathway. A significant impact of the industrial discharges on the occurrence of metals in the lakes could not be detected, and the respective concentrations in fish do not pose a public health hazard."
1254286,Asmatullah 1999,"Effect of oral administration of hexavalent chromium on total body weight, chromium uptake and histological structure of mouse liver",,"Effect of oral administration of hexavalent chromium on total body weight, chromium uptake and histological structure of mouse liver Abs: "
1254279,Chopra et al. 1996,A study of chromium and ethanol toxicity in female Wistar rats,,A study of chromium and ethanol toxicity in female Wistar rats Abs: 
1254260,NTP 1997,Final report on the reproductive toxicity of potassium dichromate (CAS No. 7778-50-9) administered in diet to BALB/c mice,,Final report on the reproductive toxicity of potassium dichromate (CAS No. 7778-50-9) administered in diet to BALB/c mice Abs: 
1252719,Goupil et al. 2009,Expression of stress-related genes in tomato plants exposed to arsenic and chromium in nutrient solution,"The molecular responses of hydroponically cultivated tomato plants to As(V) or Cr(VI) were assessed by transcript accumulation analysis of genes coding for products potentially involved in heavy metal tolerance. A quantitative real-time PCR experiment was performed with Hsp90-1, MT2- and GR1-like protein genes using RNA isolated from tomato roots or shoots treated for 24h with As(V) or Cr(VI) at concentrations ranging from 80 to 640 microM. Both transient metallic treatments induced Hsp90-1 transcript accumulation in tomato plants. MT2- and GR1-like transcripts accumulated in tomato roots treated with As(V) but were only slightly affected by Cr(VI) treatment. Tomatoes showed phenotypic symptoms to heavy metal toxicity when plants were exposed to Cr(VI) but not As(V). Plant lethality was observed at 1280 microM Cr(VI), indicating that tomatoes were more tolerant to As than Cr stress under the experimental conditions used here.","Expression of stress-related genes in tomato plants exposed to arsenic and chromium in nutrient solution Abs: The molecular responses of hydroponically cultivated tomato plants to As(V) or Cr(VI) were assessed by transcript accumulation analysis of genes coding for products potentially involved in heavy metal tolerance. A quantitative real-time PCR experiment was performed with Hsp90-1, MT2- and GR1-like protein genes using RNA isolated from tomato roots or shoots treated for 24h with As(V) or Cr(VI) at concentrations ranging from 80 to 640 microM. Both transient metallic treatments induced Hsp90-1 transcript accumulation in tomato plants. MT2- and GR1-like transcripts accumulated in tomato roots treated with As(V) but were only slightly affected by Cr(VI) treatment. Tomatoes showed phenotypic symptoms to heavy metal toxicity when plants were exposed to Cr(VI) but not As(V). Plant lethality was observed at 1280 microM Cr(VI), indicating that tomatoes were more tolerant to As than Cr stress under the experimental conditions used here."
1251320,Zagury et al. 2003,Occurrence of metals in soil and ground water near chromated copper arsenate-treated utility poles,"To thoroughly investigate the metal contamination around chromated copper arsenate (CCA)/polyethylene glycol (PEG)-treated utility poles, a total of 189 soil samples obtained from different depths and distances near six treated poles in the Montreal area (Canada) were analyzed for Cu, Cr, and As content. Various soil physicochemical properties were also determined. Ground water samples collected below the poles were analyzed for metals and bioassays with Daphnia magna were conducted. Generally, sandy soils had lower contaminant levels than clayey and organic soils. Copper concentrations in soil were highest followed by As and Cr. The highest Cu (1460 +/- 677 mg kg(-1)), As (410 +/- 150 mg kg(-1)), and Cr (287 +/- 32 mg kg(-1)) concentrations were found at the ground line and immediately adjacent to the pole. Contaminant levels then decreased with distance, approaching background levels within 0.1 m from the pole for Cr and 0.5 m for Cu and As. Chromium and Cu levels generally approached background levels at a depth of 0.5 m. Average As content near the pole on all study sites was three to eight times higher than Quebec's Level C criterion (50 mg kg(-1)), although it dropped to 31 mg kg(-1) at 0.1 m. Results also showed that As persisted up to 1 m in soil depth (17-54 mg kg(-1)). Copper and Cr concentrations in ground water samples were always &lt;1.000 mg L(-1) and &lt;0.05 mg L(-1), respectively and Cr(VI) was &lt;0.02 mg L(-1). One sample contained an As concentration &gt;0.025 mg L(-1) but bioassays showed that, overall, ground water had a low ecotoxic potential.","Occurrence of metals in soil and ground water near chromated copper arsenate-treated utility poles Abs: To thoroughly investigate the metal contamination around chromated copper arsenate (CCA)/polyethylene glycol (PEG)-treated utility poles, a total of 189 soil samples obtained from different depths and distances near six treated poles in the Montreal area (Canada) were analyzed for Cu, Cr, and As content. Various soil physicochemical properties were also determined. Ground water samples collected below the poles were analyzed for metals and bioassays with Daphnia magna were conducted. Generally, sandy soils had lower contaminant levels than clayey and organic soils. Copper concentrations in soil were highest followed by As and Cr. The highest Cu (1460 +/- 677 mg kg(-1)), As (410 +/- 150 mg kg(-1)), and Cr (287 +/- 32 mg kg(-1)) concentrations were found at the ground line and immediately adjacent to the pole. Contaminant levels then decreased with distance, approaching background levels within 0.1 m from the pole for Cr and 0.5 m for Cu and As. Chromium and Cu levels generally approached background levels at a depth of 0.5 m. Average As content near the pole on all study sites was three to eight times higher than Quebec's Level C criterion (50 mg kg(-1)), although it dropped to 31 mg kg(-1) at 0.1 m. Results also showed that As persisted up to 1 m in soil depth (17-54 mg kg(-1)). Copper and Cr concentrations in ground water samples were always &lt;1.000 mg L(-1) and &lt;0.05 mg L(-1), respectively and Cr(VI) was &lt;0.02 mg L(-1). One sample contained an As concentration &gt;0.025 mg L(-1) but bioassays showed that, overall, ground water had a low ecotoxic potential."
1251104,Gezer and  Cooper 2009,Factors affecting sodium hypochlorite extraction of CCA from treated wood,"Significant amounts of chromated copper arsenate (CCA) treated wood products, such as utility poles and residential construction wood, remain in service. There is increasing public concern about environmental contamination from CCA-treated wood when it is removed from service for reuse or recycling, placed in landfills or burned in commercial incinerators. In this paper, we investigated the effects of time, temperature and sodium hypochlorite concentration on chromium oxidation and extraction of chromated copper arsenate from CCA-treated wood (Type C) removed from service. Of the conditions evaluated, reaction of milled wood with sodium hypochlorite for one hour at room temperature followed by heating at 75 degrees C for two hours gave the highest extraction efficiency. An average of 95% Cr, 99% Cu and 96% As could be removed from CCA-treated, milled wood by this process. Most of the extracted chromium was oxidized to the hexavalent state and could therefore be recycled in a CCA treating solution. Sodium hypochlorite extracting solutions could be reused several times to extract CCA components from additional treated wood samples.","Factors affecting sodium hypochlorite extraction of CCA from treated wood Abs: Significant amounts of chromated copper arsenate (CCA) treated wood products, such as utility poles and residential construction wood, remain in service. There is increasing public concern about environmental contamination from CCA-treated wood when it is removed from service for reuse or recycling, placed in landfills or burned in commercial incinerators. In this paper, we investigated the effects of time, temperature and sodium hypochlorite concentration on chromium oxidation and extraction of chromated copper arsenate from CCA-treated wood (Type C) removed from service. Of the conditions evaluated, reaction of milled wood with sodium hypochlorite for one hour at room temperature followed by heating at 75 degrees C for two hours gave the highest extraction efficiency. An average of 95% Cr, 99% Cu and 96% As could be removed from CCA-treated, milled wood by this process. Most of the extracted chromium was oxidized to the hexavalent state and could therefore be recycled in a CCA treating solution. Sodium hypochlorite extracting solutions could be reused several times to extract CCA components from additional treated wood samples."
1249018,Proctor et al. 2012,Hexavalent chromium reduction kinetics in rodent stomach contents,"Reduction of hexavalent chromium (Cr(VI)) to trivalent chromium (Cr(III)) in the stomach prior to absorption is a well-recognized detoxification process thought to limit the toxicity of ingested Cr(VI). However, administration of high concentrations of Cr(VI) in drinking water cause mouse small intestinal tumors, and quantitative measures of Cr(VI) reduction rate and capacity for rodent stomach contents are needed for interspecies extrapolation using physiologically-based toxicokinetic (PBTK) models. Ex vivo studies using stomach contents of rats and mice were conducted to quantify Cr(VI) reduction rate and capacity for loading rates (1-400mg Cr(VI)L(-1) stomach contents) in the range of recent bioassays. Cr(VI) reduction was measured with speciated isotope dilution mass spectrometry to quantify dynamic Cr(VI) and Cr(III) concentrations in stomach contents at select time points over 1h. Cr(VI) reduction followed mixed second-order kinetics, dependent upon concentrations of both Cr(VI) and the native reducing agents. Approximately 16mg Cr(VI)-equivalents of reducing capacity per L of fed stomach contents (containing gastric secretions, saliva, water and food) was found for both species. The second-order rate constants were 0.2 and 0.3Lmg(-1)h(-1) for mice and rats, respectively. These findings support that, at the doses that caused cancer in the mouse small intestine (?20mg Cr(VI)L(-1) in drinking water), the reducing capacity of stomach contents was likely exceeded. Thus, for extrapolation of target tissue dose in risk assessment, PBTK models are necessary to account for competing kinetic rates including second order capacity-limited reduction of Cr(VI) to Cr(III).","Hexavalent chromium reduction kinetics in rodent stomach contents Abs: Reduction of hexavalent chromium (Cr(VI)) to trivalent chromium (Cr(III)) in the stomach prior to absorption is a well-recognized detoxification process thought to limit the toxicity of ingested Cr(VI). However, administration of high concentrations of Cr(VI) in drinking water cause mouse small intestinal tumors, and quantitative measures of Cr(VI) reduction rate and capacity for rodent stomach contents are needed for interspecies extrapolation using physiologically-based toxicokinetic (PBTK) models. Ex vivo studies using stomach contents of rats and mice were conducted to quantify Cr(VI) reduction rate and capacity for loading rates (1-400mg Cr(VI)L(-1) stomach contents) in the range of recent bioassays. Cr(VI) reduction was measured with speciated isotope dilution mass spectrometry to quantify dynamic Cr(VI) and Cr(III) concentrations in stomach contents at select time points over 1h. Cr(VI) reduction followed mixed second-order kinetics, dependent upon concentrations of both Cr(VI) and the native reducing agents. Approximately 16mg Cr(VI)-equivalents of reducing capacity per L of fed stomach contents (containing gastric secretions, saliva, water and food) was found for both species. The second-order rate constants were 0.2 and 0.3Lmg(-1)h(-1) for mice and rats, respectively. These findings support that, at the doses that caused cancer in the mouse small intestine (?20mg Cr(VI)L(-1) in drinking water), the reducing capacity of stomach contents was likely exceeded. Thus, for extrapolation of target tissue dose in risk assessment, PBTK models are necessary to account for competing kinetic rates including second order capacity-limited reduction of Cr(VI) to Cr(III)."
1248722,Alikhan and  Maibach 2011,Topical absorption and systemic toxicity,"Dermal absorption of some chemicals and drugs can cause systemic toxicity. We evaluated several case reports from the past decade, which discuss the dermal absorption of a specific chemical and potential local and systemic effects. We focused on herbicide and pesticide exposure along with exposure to cutaneous medication, occupational contact, and cosmeceutical exposure. Although causality cannot be established in most cases, it is critical to be aware of the possible effects of topical absorption that may not be immediately apparent. We recommended further studies on specific chemicals to ascertain causality and determine the highest exposure level with no observed adverse affect level (NOAEL) and the reference dose (RfD). Post-marketing epidemiology data in most geographical areas are markedly limited. A weak link in public health resides in the inadequate reporting and workup of alleged chemically related adverse effects. This arena mandates a re-thinking of how to increase this reporting, and workup, as a backup to our preclinical and clinical studies. Public awareness and funding will be rewarded by increased evidence to backup pre-approval pre-marketing studies.","Topical absorption and systemic toxicity Abs: Dermal absorption of some chemicals and drugs can cause systemic toxicity. We evaluated several case reports from the past decade, which discuss the dermal absorption of a specific chemical and potential local and systemic effects. We focused on herbicide and pesticide exposure along with exposure to cutaneous medication, occupational contact, and cosmeceutical exposure. Although causality cannot be established in most cases, it is critical to be aware of the possible effects of topical absorption that may not be immediately apparent. We recommended further studies on specific chemicals to ascertain causality and determine the highest exposure level with no observed adverse affect level (NOAEL) and the reference dose (RfD). Post-marketing epidemiology data in most geographical areas are markedly limited. A weak link in public health resides in the inadequate reporting and workup of alleged chemically related adverse effects. This arena mandates a re-thinking of how to increase this reporting, and workup, as a backup to our preclinical and clinical studies. Public awareness and funding will be rewarded by increased evidence to backup pre-approval pre-marketing studies."
1247653,NTP 1996,Final report on the reproductive toxicity of potassium dichromate (hexavalent) (CAS No. 7778-50-9) administered in diet to BALB/c mice,,Final report on the reproductive toxicity of potassium dichromate (hexavalent) (CAS No. 7778-50-9) administered in diet to BALB/c mice Abs: 
1247646,NTP 1996,Final report on the reproductive toxicity of potassium dichromate (hexavalent) (CAS No. 7778-50-9) administered in diet to SD rats,,Final report on the reproductive toxicity of potassium dichromate (hexavalent) (CAS No. 7778-50-9) administered in diet to SD rats Abs: 
1247497,Zahid et al. 1990,Comparative effects of trivalent and hexavalent chromium on spermatogenesis of the mouse,,Comparative effects of trivalent and hexavalent chromium on spermatogenesis of the mouse Abs: 
1247284,Gammelgaard et al. 1999,In vitro metabolism and permeation studies in rat jejunum: Organic chromium compared to inorganic chromium,"The purpose of these studies was to compare the in vitro absorption of two inorganic chromium(III) compounds: chromium chloride and chromium nitrate, with organic chromium(III)-picolinate; and to investigate if any in vitro metabolism of chromium(VI) takes place. The in vitro metabolism studies showed that chromium (VI) was reduced by artificial gastric juice. The reduction followed first order kinetics with a half-life of 23 min. The studies also showed that the chromium picolinate complex was stable in artificial gastric juice for 4 hours. By the rat everted gut sac technique, chromium chloride, chromium nitrate and chromium picolinate penetrated the rat jejunum with 165 +/- 59, 160 +/- 26 and 127 +/- 36 ng chromium per g rat jejunum, respectively, whereas the permeability coefficients (Papp) were 0.7 +/- 0.3, 1.0 +/- 0.4, and 9.6 +/- 2.2 microns/min, respectively. Absorption studies on pig intestine in Ussing chambers showed a nearly total adsorption of chromium(III) by the chambers, resulting in unreliable data.","In vitro metabolism and permeation studies in rat jejunum: Organic chromium compared to inorganic chromium Abs: The purpose of these studies was to compare the in vitro absorption of two inorganic chromium(III) compounds: chromium chloride and chromium nitrate, with organic chromium(III)-picolinate; and to investigate if any in vitro metabolism of chromium(VI) takes place. The in vitro metabolism studies showed that chromium (VI) was reduced by artificial gastric juice. The reduction followed first order kinetics with a half-life of 23 min. The studies also showed that the chromium picolinate complex was stable in artificial gastric juice for 4 hours. By the rat everted gut sac technique, chromium chloride, chromium nitrate and chromium picolinate penetrated the rat jejunum with 165 +/- 59, 160 +/- 26 and 127 +/- 36 ng chromium per g rat jejunum, respectively, whereas the permeability coefficients (Papp) were 0.7 +/- 0.3, 1.0 +/- 0.4, and 9.6 +/- 2.2 microns/min, respectively. Absorption studies on pig intestine in Ussing chambers showed a nearly total adsorption of chromium(III) by the chambers, resulting in unreliable data."
1246935,Wcislo 2012,Polish Soil Quality Standards Versus Risk-Based Soil Screening Levels for Metals and Arsenic,,Polish Soil Quality Standards Versus Risk-Based Soil Screening Levels for Metals and Arsenic Abs: 
1242649,Sinicropi et al. 2010,Chemical and biological properties of toxic metals and use of chelating agents for the pharmacological treatment of metal poisoning,"Exposure to toxic metals is a well-known problem in industrialized countries. Metals interfere with a number of physiological processes, including central nervous system (CNS), haematopoietic, hepatic and renal functions. In the evaluation of the toxicity of a particular metal it is crucial to consider many parameters: chemical forms (elemental, organic or inorganic), binding capability, presence of specific proteins that selectively bind metals, etc. Medical treatment of acute and chronic metal toxicity is provided by chelating agents, namely organic compounds capable of interacting with metal ions to form structures called chelates. The present review attempts to provide updated information about the mechanisms, the cellular targets and the effects of toxic metals.","Chemical and biological properties of toxic metals and use of chelating agents for the pharmacological treatment of metal poisoning Abs: Exposure to toxic metals is a well-known problem in industrialized countries. Metals interfere with a number of physiological processes, including central nervous system (CNS), haematopoietic, hepatic and renal functions. In the evaluation of the toxicity of a particular metal it is crucial to consider many parameters: chemical forms (elemental, organic or inorganic), binding capability, presence of specific proteins that selectively bind metals, etc. Medical treatment of acute and chronic metal toxicity is provided by chelating agents, namely organic compounds capable of interacting with metal ions to form structures called chelates. The present review attempts to provide updated information about the mechanisms, the cellular targets and the effects of toxic metals."
1239159,Royal Cancer Hospital 1992,Initial submission: Effects of various chromium-containing materials on rat lung epithelium (study conclusions only) with cover letter dated 10/15/92,,Initial submission: Effects of various chromium-containing materials on rat lung epithelium (study conclusions only) with cover letter dated 10/15/92 Abs: 
1239106,IBT Labs 1978,"Letter from PPG Industries, Inc. to USEPA submitting enclosed toxicity studies on sodium chromated crystals, sodium dichromate dihydrate and chronium trioxide with attachments","Chromium trioxide, [I], and sodium chromate, [II], were evaluated for acute oral toxicity to Sprague-Dawley rats (10/group) administered single doses of 0, 50 or 500 mg/kg by gavage. Summary information indicates no adverse effects were noted in the low dose groups, and 100% mortality was seen in high-dose rats. Acute dermal toxicity assays of [I], [II], and sodium bichromate (69% liquid), [III], with albino rabbits administered 20, 200, or 1,000 mg/kg led to severe diarrhea, followed by death, in all mid- and high-dose animals treated with [I] or [II], and hypoactivity and muscular weakness in high-dose rabbits receiving [III]. Death was noted only in the high-dose groups given [III]. Severe irritation to the skin was noted with all treated rabbits. Instillation of 100 mg, undiluted, of [I] or [III], or 0.1 ml of 27.5% hydrogen peroxide in unwashed eyes of albino rabbits led to severe corrosion within 1 hour after treatment, and exposure to [II] was severely irritating to eyes. Administration of 500 mg of undiluted [I] or [II] to albino rabbit skin led to 3rd degree burns in all treated animals at both intact and abraded skin sites, while similar exposure to [III] was not corrosive.","Letter from PPG Industries, Inc. to USEPA submitting enclosed toxicity studies on sodium chromated crystals, sodium dichromate dihydrate and chronium trioxide with attachments Abs: Chromium trioxide, [I], and sodium chromate, [II], were evaluated for acute oral toxicity to Sprague-Dawley rats (10/group) administered single doses of 0, 50 or 500 mg/kg by gavage. Summary information indicates no adverse effects were noted in the low dose groups, and 100% mortality was seen in high-dose rats. Acute dermal toxicity assays of [I], [II], and sodium bichromate (69% liquid), [III], with albino rabbits administered 20, 200, or 1,000 mg/kg led to severe diarrhea, followed by death, in all mid- and high-dose animals treated with [I] or [II], and hypoactivity and muscular weakness in high-dose rabbits receiving [III]. Death was noted only in the high-dose groups given [III]. Severe irritation to the skin was noted with all treated rabbits. Instillation of 100 mg, undiluted, of [I] or [III], or 0.1 ml of 27.5% hydrogen peroxide in unwashed eyes of albino rabbits led to severe corrosion within 1 hour after treatment, and exposure to [II] was severely irritating to eyes. Administration of 500 mg of undiluted [I] or [II] to albino rabbit skin led to 3rd degree burns in all treated animals at both intact and abraded skin sites, while similar exposure to [III] was not corrosive."
1239082,Boeing 1988,Auburn reproductive health survey with cover letter dated 020888,,Auburn reproductive health survey with cover letter dated 020888 Abs: 
1239058,U.S. EPA 1982,Results of the Air Monitoring with Cover Letter & Attachments,"Results of the Air Monitoring Conducted July 19,1979 at the _______","Results of the Air Monitoring with Cover Letter & Attachments Abs: Results of the Air Monitoring Conducted July 19,1979 at the _______"
1239052,Flynn and  Susi 2004,A review of engineering control technology for exposures generated during abrasive blasting operations,"This literature review focused on measures for controlling worker exposure to toxic airborne contaminants generated during abrasive blasting operations occurring primarily in the construction industry. The exposures of concern include respirable crystalline silica, lead, chromates and other toxic metals. Unfortunately, silica sand continues to be widely used in the United States as an abrasive blasting medium, resulting in high exposures for operators and surrounding personnel. Recently, several alternative abrasives have emerged as potential substitutes for sand, but they seem to be underused. Some of these abrasives may pose additional metal exposure hazards. Several new and improved technologies offer promise for reducing or eliminating exposures; these include wet abrasive blasting, high-pressure water jetting, vacuum blasting, and automated systems.","A review of engineering control technology for exposures generated during abrasive blasting operations Abs: This literature review focused on measures for controlling worker exposure to toxic airborne contaminants generated during abrasive blasting operations occurring primarily in the construction industry. The exposures of concern include respirable crystalline silica, lead, chromates and other toxic metals. Unfortunately, silica sand continues to be widely used in the United States as an abrasive blasting medium, resulting in high exposures for operators and surrounding personnel. Recently, several alternative abrasives have emerged as potential substitutes for sand, but they seem to be underused. Some of these abrasives may pose additional metal exposure hazards. Several new and improved technologies offer promise for reducing or eliminating exposures; these include wet abrasive blasting, high-pressure water jetting, vacuum blasting, and automated systems."
1239044,ANON 1996,Zinc chromate,"Data sheet. May enter the body when breathed in. It is a carcinogen and should be handled with extreme caution. May irritate the skin, eyes and respiratory tract. May perforate the nasal septum. May cause skin allergy.","Zinc chromate Abs: Data sheet. May enter the body when breathed in. It is a carcinogen and should be handled with extreme caution. May irritate the skin, eyes and respiratory tract. May perforate the nasal septum. May cause skin allergy."
1239043,ANON 1996,Potassium dichromate,"Data sheet. May enter the body when breathed in. It is a carcinogen and should be handled with extreme caution. Irritates and burns the skin, eyes and respiratory tract. May damage the eyes. May cause skin allergy. May cause a sore or a hole in the bone dividing the inner nose.","Potassium dichromate Abs: Data sheet. May enter the body when breathed in. It is a carcinogen and should be handled with extreme caution. Irritates and burns the skin, eyes and respiratory tract. May damage the eyes. May cause skin allergy. May cause a sore or a hole in the bone dividing the inner nose."
1239042,Perrault et al. 1995,Localization and oxidation state of chromium in some industrial aerosols,"Aerosol samples were collected during manual metal arc stainless steel welding, surface treatment by spraying of a chromate solution, plastic coloration with lead chromate pigment and electrolytic plating. The levels of the different chemical forms of chromium were not always the same in the total and respirable fractions of the samples. The sampling of total dust is recommended for welding fumes from stainless steel. The sampling of respirable dust would be the best practice in terms of health protection at the three other worksites of the study. Determination of total chromium and total chromium VI are recommended for chromium electroplating. At the present stage of scientific knowledge, the analysis of soluble chromium VI is still recommended, in spite of its analytical difficulties, for spraying and stainless steel welding, with the addition of insoluble chromium VI in the case of plastic coloration.","Localization and oxidation state of chromium in some industrial aerosols Abs: Aerosol samples were collected during manual metal arc stainless steel welding, surface treatment by spraying of a chromate solution, plastic coloration with lead chromate pigment and electrolytic plating. The levels of the different chemical forms of chromium were not always the same in the total and respirable fractions of the samples. The sampling of total dust is recommended for welding fumes from stainless steel. The sampling of respirable dust would be the best practice in terms of health protection at the three other worksites of the study. Determination of total chromium and total chromium VI are recommended for chromium electroplating. At the present stage of scientific knowledge, the analysis of soluble chromium VI is still recommended, in spite of its analytical difficulties, for spraying and stainless steel welding, with the addition of insoluble chromium VI in the case of plastic coloration."
1239039,Chiba et al. 1994,Case report: Arsenic-exposed patient with polyneuritis,"A 50-year-old male carpenter complained of numbness in the upper and lower limbs. Because of his having been exposed to airborne dust containing arsenic pentoxide, potassium dichromate and copper sulfate as wood preservatives, he was suspected of having contracted neuritis caused by arsenic poisoning. No irregularity was found except dysaesthesia in the four limbs and light hypoaesthesia in the hands and legs. Paraneoplastic neuropathy, amyloidosis and Sjogren's syndrome were ruled out. Arsenic (As), chromium (Cr) and copper (Cu) concentrations in scalp hair, fingernail, plasma, erythrocytes and urine were determined. As and Cr concentrations were much higher than in controls. There was no difference in Cu concentration between the patient and the control. This suggests that the patient's polyneuritis was due to arsenic poisoning.","Case report: Arsenic-exposed patient with polyneuritis Abs: A 50-year-old male carpenter complained of numbness in the upper and lower limbs. Because of his having been exposed to airborne dust containing arsenic pentoxide, potassium dichromate and copper sulfate as wood preservatives, he was suspected of having contracted neuritis caused by arsenic poisoning. No irregularity was found except dysaesthesia in the four limbs and light hypoaesthesia in the hands and legs. Paraneoplastic neuropathy, amyloidosis and Sjogren's syndrome were ruled out. Arsenic (As), chromium (Cr) and copper (Cu) concentrations in scalp hair, fingernail, plasma, erythrocytes and urine were determined. As and Cr concentrations were much higher than in controls. There was no difference in Cu concentration between the patient and the control. This suggests that the patient's polyneuritis was due to arsenic poisoning."
1239038,Stein 1992,Sensitization by chromates in leather,Published epidemiologic studies on children and teenagers wearing ordinary leather shoes and adults wearing safety shoes show a connection between foot eczema and chromates in the shoes. Sensitization by chromates requires the presence of sweat in the shoe. Trivalent chromium is frequently used as a tanning agent. The use of safety shoes made of leather tanned with phytogenic agents is recommended. Summaries in English and French.,Sensitization by chromates in leather Abs: Published epidemiologic studies on children and teenagers wearing ordinary leather shoes and adults wearing safety shoes show a connection between foot eczema and chromates in the shoes. Sensitization by chromates requires the presence of sweat in the shoe. Trivalent chromium is frequently used as a tanning agent. The use of safety shoes made of leather tanned with phytogenic agents is recommended. Summaries in English and French.
1239035,Kellard 1991,Hazardous substances - Carcinogens guide,"This guide is designed for safety officers, occupational hygienists and laboratory workers and aims to provide authoritative reference information on workplace carcinogens. All substances which come within the scope of the British COSHH Regulations (see CIS 89-1092) are included. For each of the 61 substances listed, the following information is provided: chemical identity; properties; uses; carcinogenicity in humans and animals. An introduction includes details of the legislation related to occupational cancer and an overview of the identification and classification of carcinogens.","Hazardous substances - Carcinogens guide Abs: This guide is designed for safety officers, occupational hygienists and laboratory workers and aims to provide authoritative reference information on workplace carcinogens. All substances which come within the scope of the British COSHH Regulations (see CIS 89-1092) are included. For each of the 61 substances listed, the following information is provided: chemical identity; properties; uses; carcinogenicity in humans and animals. An introduction includes details of the legislation related to occupational cancer and an overview of the identification and classification of carcinogens."
1239033,ANON 1991,Lead chromate (VI),"International chemical safety card. Short-term exposure effects: irritation of the respiratory tract; delayed effects; toxic effects from exposure to lead. Long-term exposure effects: dermatitis; lung diseases; may have effects on the kidneys, lungs, liver, blood, nervous and reproductive systems; probably carcinogenic in humans; possible genetic and teratogenic effects in humans.","Lead chromate (VI) Abs: International chemical safety card. Short-term exposure effects: irritation of the respiratory tract; delayed effects; toxic effects from exposure to lead. Long-term exposure effects: dermatitis; lung diseases; may have effects on the kidneys, lungs, liver, blood, nervous and reproductive systems; probably carcinogenic in humans; possible genetic and teratogenic effects in humans."
1239030,National Board of Labour Protection 1989,Ammonium dichromate,"Translation into English of the chemical safety information sheet described in CIS 88-55. Ammonium dichromate is an explosive, sensitising, carcinogenic agent (LD[5][0] = 30mg/kg; TLV = 0.05mg/m|3|). The powder irritates and corrodes the skin, the respiratory tract, the conjunctiva of the eye and the mucous membranes. Can cause asthma. Long-term exposure causes hand lesions. Can cause eczema and lung cancer. Mandatory European labelling: E, Xi, R1, R8, R36, R37, R38, R43, R103, S28, S35, S101, S103.","Ammonium dichromate Abs: Translation into English of the chemical safety information sheet described in CIS 88-55. Ammonium dichromate is an explosive, sensitising, carcinogenic agent (LD[5][0] = 30mg/kg; TLV = 0.05mg/m|3|). The powder irritates and corrodes the skin, the respiratory tract, the conjunctiva of the eye and the mucous membranes. Can cause asthma. Long-term exposure causes hand lesions. Can cause eczema and lung cancer. Mandatory European labelling: E, Xi, R1, R8, R36, R37, R38, R43, R103, S28, S35, S101, S103."
1239026,ANON 1988,Sodium chromate,"Chemical hazard summary. Toxicity: irritation of skin, eyes and respiratory and digestive tracts; skin absorption; perforation of the nasal septum; skin ulcers; dermatitis; skin sensitisation; renal damage.","Sodium chromate Abs: Chemical hazard summary. Toxicity: irritation of skin, eyes and respiratory and digestive tracts; skin absorption; perforation of the nasal septum; skin ulcers; dermatitis; skin sensitisation; renal damage."
1239021,ANON 1988,Proposal for a Council Directive on the protection of workers from the risks related to exposure to carcinogens at work ðCEC,"Sixth individual Directive within the meaning of Article 8 of Directive 80/1107. Chemicals and industrial processes considered carcinogenic are designated in the Annex. The Directive defines: measures preventing exposure; the kind of information employers have to make available to the competent authorities; measures to be taken in case of abnormal exposures; conditions of access to areas. Other aspects dealt with: protective clothing and equipment, information and training, health surveillance, record keeping.","Proposal for a Council Directive on the protection of workers from the risks related to exposure to carcinogens at work ðCEC Abs: Sixth individual Directive within the meaning of Article 8 of Directive 80/1107. Chemicals and industrial processes considered carcinogenic are designated in the Annex. The Directive defines: measures preventing exposure; the kind of information employers have to make available to the competent authorities; measures to be taken in case of abnormal exposures; conditions of access to areas. Other aspects dealt with: protective clothing and equipment, information and training, health surveillance, record keeping."
1239019,ANON 1988,Chromium trioxide,"Chemical safety information sheet. Exposure limits (France, 1985): TWA = 0.05mg/m|3|; ceiling value = 0.1mg/m|3|. Acute toxicity: severe skin and eye burns; irritation and ulceration of mucous membranes. Chronic toxicity: human carcinogen; skin and nasal septum ulcers; renal damage (ingestion). EEC identification number and labelling codes: No.024-001-00-0; C, O, R8, R35, R43, S28.","Chromium trioxide Abs: Chemical safety information sheet. Exposure limits (France, 1985): TWA = 0.05mg/m|3|; ceiling value = 0.1mg/m|3|. Acute toxicity: severe skin and eye burns; irritation and ulceration of mucous membranes. Chronic toxicity: human carcinogen; skin and nasal septum ulcers; renal damage (ingestion). EEC identification number and labelling codes: No.024-001-00-0; C, O, R8, R35, R43, S28."
1239018,Lindberg 1986,Health hazards in chrome plating work,"Report on a study of exposure conditions in the Swedish chrome plating industry and a clinical examination of the impact of exposure on airways, pulmonary and renal function. A cohort study of cancer mortality in chrome plating workers and spray painters who had used paint containing lead chromate and zinc chromate was also made. Correlations found between different levels of mean daily airborne exposure, expressed in |g of Cr(VI)/m|3| and complaints/examination findings in the airways are presented (nasal irritation, atrophy of septal mucosa, ulceration of the nasal septum, impairment of pulmonary function). A comparison with the national average showed that cancer mortality in cohorts was in close agreement with the expected figure. However, cancer deaths concentrated in groups with long-term exposure to high concentrations of chromates.","Health hazards in chrome plating work Abs: Report on a study of exposure conditions in the Swedish chrome plating industry and a clinical examination of the impact of exposure on airways, pulmonary and renal function. A cohort study of cancer mortality in chrome plating workers and spray painters who had used paint containing lead chromate and zinc chromate was also made. Correlations found between different levels of mean daily airborne exposure, expressed in |g of Cr(VI)/m|3| and complaints/examination findings in the airways are presented (nasal irritation, atrophy of septal mucosa, ulceration of the nasal septum, impairment of pulmonary function). A comparison with the national average showed that cancer mortality in cohorts was in close agreement with the expected figure. However, cancer deaths concentrated in groups with long-term exposure to high concentrations of chromates."
1239016,ANON 1987,Carcinogenicutagenic/Teratogenic (C/M/T) Substances (Classification and labelling within the framework of directive 67/548/EEC) ðEuropean Communities,"This list details C/T substances which have been classified within the framework of Directive 67/548/EEC (CIS 86-1574); suspected C/M/T substances which are under discussion in the Working Group ""Classification and labelling of carcinogenic substances"", suspected C/M/T substances for which Member States have informed the Commission that they are preparing data sheets, or for which the Commission is preparing data sheets for submission to the Working Group ""Classification and labelling of carcinogenic substances"".","Carcinogenicutagenic/Teratogenic (C/M/T) Substances (Classification and labelling within the framework of directive 67/548/EEC) ðEuropean Communities Abs: This list details C/T substances which have been classified within the framework of Directive 67/548/EEC (CIS 86-1574); suspected C/M/T substances which are under discussion in the Working Group ""Classification and labelling of carcinogenic substances"", suspected C/M/T substances for which Member States have informed the Commission that they are preparing data sheets, or for which the Commission is preparing data sheets for submission to the Working Group ""Classification and labelling of carcinogenic substances""."
1239015,Foussereau 1986,Allergens of the standard battery in occupational and non-occupational environments,"Information note for occupational physicians. Presentation of the standard battery established by the International Contact Dermatitis Research Group (ICDRG). For each of the 22 allergens: generalities; industrial sectors or occupations where exposure occurs; conditions of non-occupational exposure. The allergens: chromium (potassium bichromate), nickel, cobalt, p-phenylenediamine, benzocaine, rubber (4 different mixtures), formaldehyde, epoxy resin, vosin and derivatives, Peru balsam, lanolin, neomycin, parfumes, parabens, formaldehyde-p-t-butylphenol resin, quaternium 15, primine, ethylenediamine hydrochloride, quinolines. In France, thimerosol and Frullania are added to the list.","Allergens of the standard battery in occupational and non-occupational environments Abs: Information note for occupational physicians. Presentation of the standard battery established by the International Contact Dermatitis Research Group (ICDRG). For each of the 22 allergens: generalities; industrial sectors or occupations where exposure occurs; conditions of non-occupational exposure. The allergens: chromium (potassium bichromate), nickel, cobalt, p-phenylenediamine, benzocaine, rubber (4 different mixtures), formaldehyde, epoxy resin, vosin and derivatives, Peru balsam, lanolin, neomycin, parfumes, parabens, formaldehyde-p-t-butylphenol resin, quaternium 15, primine, ethylenediamine hydrochloride, quinolines. In France, thimerosol and Frullania are added to the list."
1239014,ANON 1985,Ammonium dichromate,"Ammonium dichromate is an explosive, sensitising, carcinogenic agent (LD[5][0] = 30mg/kg; TLV = 0.05mg/m|3|). The powder irritates and corrodes the skin, the respiratory tract, the conjunctiva of the eye and the mucous membranes. Can cause asthma. Long term exposure causes hand lesions. Can cause eczema and lung cancer. Mandatory European labelling: E, XI, R1, R8, R36, R37, R38, R43, R103, S28, S35, S101, S103.","Ammonium dichromate Abs: Ammonium dichromate is an explosive, sensitising, carcinogenic agent (LD[5][0] = 30mg/kg; TLV = 0.05mg/m|3|). The powder irritates and corrodes the skin, the respiratory tract, the conjunctiva of the eye and the mucous membranes. Can cause asthma. Long term exposure causes hand lesions. Can cause eczema and lung cancer. Mandatory European labelling: E, XI, R1, R8, R36, R37, R38, R43, R103, S28, S35, S101, S103."
1239013,Sigova and  Blohin 1984,Toxicological characteristics of chromium phosphate binders,"Chromophosphate binders are expected to find wide use in refractories and pigments. Chromium phosphate itself and mixtures containing copper, nickel, calcium-nickel and calcium-aluminium chromates were administered topically, intragastrically and by inhalation to rabbits, mice and rats. The compounds were irritant, producing gastritis on ingestion and brochitis on inhalation. LD[5][0]s ranged from 0.31 to 4.30g/kg, depending on compound and species. The mixtures were more toxic than pure chromium phosphate. The following MACs are proposed: for chromium phosphate and copper chromophosphate 0.02mg/m|3| as chromium; for calcium aluminium chromophosphate 0.01mg/m|3| as chromic oxide; for nickel chromophosphate and calcium nickel chromophosphate 0.005mg/m|3| as nickel.","Toxicological characteristics of chromium phosphate binders Abs: Chromophosphate binders are expected to find wide use in refractories and pigments. Chromium phosphate itself and mixtures containing copper, nickel, calcium-nickel and calcium-aluminium chromates were administered topically, intragastrically and by inhalation to rabbits, mice and rats. The compounds were irritant, producing gastritis on ingestion and brochitis on inhalation. LD[5][0]s ranged from 0.31 to 4.30g/kg, depending on compound and species. The mixtures were more toxic than pure chromium phosphate. The following MACs are proposed: for chromium phosphate and copper chromophosphate 0.02mg/m|3| as chromium; for calcium aluminium chromophosphate 0.01mg/m|3| as chromic oxide; for nickel chromophosphate and calcium nickel chromophosphate 0.005mg/m|3| as nickel."
1239006,Morel et al. 1983,Sodium and potassium chromates and dichromates,"Synonyms, uses, physical and chemical properties, methods of detection and determination in air, fire hazards, pathology and toxicology (acute and chronic experimental toxicity, mutagenicity and carcinogenicity tests, toxicity for humans: digestive disorders, bronchial irritation, skin ulceration, allergic dermatitis, corrosive action on the mucous membranes, etc.; American TLV (ACGIH) for hexavalent water-soluble chromium compounds: 0.05mg/m|3|). Information on French regulations concerning health and safety and on French and international regulations concerning transport. Technical and medical recommendations.","Sodium and potassium chromates and dichromates Abs: Synonyms, uses, physical and chemical properties, methods of detection and determination in air, fire hazards, pathology and toxicology (acute and chronic experimental toxicity, mutagenicity and carcinogenicity tests, toxicity for humans: digestive disorders, bronchial irritation, skin ulceration, allergic dermatitis, corrosive action on the mucous membranes, etc.; American TLV (ACGIH) for hexavalent water-soluble chromium compounds: 0.05mg/m|3|). Information on French regulations concerning health and safety and on French and international regulations concerning transport. Technical and medical recommendations."
1239003,Puchalska et al. 1982,Influence of the working environment on the dynamics of skin allergy symptoms,"Studies in guinea-pigs are reported aimed at investigating the combined effects of chemical and physical factors, and at determining the influence of high temperatures and noise on skin allergies caused by 2,4-dinitrochlorobenzene, potassium dichromate and a cutting fluid (Emulgrind). Appearance of skin lesions, peripheral blood changes and urinary alkaline phosphatase (AP) and fructose diphosphate aldolase (ALd) activities were most pronounced when all 3 factors (allergen, heat, noise) were present. The allergic potential of the substances studied was not affected by noise alone. While incomplete, the results indicate the usefulness of AP and Ald determinations in the 24h urine for evaluating the allergic pathology.","Influence of the working environment on the dynamics of skin allergy symptoms Abs: Studies in guinea-pigs are reported aimed at investigating the combined effects of chemical and physical factors, and at determining the influence of high temperatures and noise on skin allergies caused by 2,4-dinitrochlorobenzene, potassium dichromate and a cutting fluid (Emulgrind). Appearance of skin lesions, peripheral blood changes and urinary alkaline phosphatase (AP) and fructose diphosphate aldolase (ALd) activities were most pronounced when all 3 factors (allergen, heat, noise) were present. The allergic potential of the substances studied was not affected by noise alone. While incomplete, the results indicate the usefulness of AP and Ald determinations in the 24h urine for evaluating the allergic pathology."
1239000,Stern 1982,Chromium compounds: production and occupational exposure,"Brief description of the production of chromium-containing chemicals and alloys, and literature survey of occupational exposure in the welding, chromate, chromium plating, ferrochromium, tanning and leather working and chromium pigment industries. For most occupations, exposure is to a mixture of Cr oxidation states and solubility fractions with a few notable exceptions: in the tanning industry, exposure is almost exclusively to soluble Cr(III), in the plating industry to soluble Cr(VI), and in the pigment industry, some wokers handling only lead chromate are exposed primarily to insoluble Cr(VI). Because of the wide variety of physical and chemical characteristics of the material of which airborne occupational exposures are composed, one can expect that the deposition, accumulation, clearance, bioavailability and pharmacokinetics of chromium differs widely from industry to industry, and great care must be taken in comparing exposures.","Chromium compounds: production and occupational exposure Abs: Brief description of the production of chromium-containing chemicals and alloys, and literature survey of occupational exposure in the welding, chromate, chromium plating, ferrochromium, tanning and leather working and chromium pigment industries. For most occupations, exposure is to a mixture of Cr oxidation states and solubility fractions with a few notable exceptions: in the tanning industry, exposure is almost exclusively to soluble Cr(III), in the plating industry to soluble Cr(VI), and in the pigment industry, some wokers handling only lead chromate are exposed primarily to insoluble Cr(VI). Because of the wide variety of physical and chemical characteristics of the material of which airborne occupational exposures are composed, one can expect that the deposition, accumulation, clearance, bioavailability and pharmacokinetics of chromium differs widely from industry to industry, and great care must be taken in comparing exposures."
1238998,Lidâen 1981,Occupational skin disease in a film laboratory,"Study carried out in a film developing laboratory employing 114 people of whom 43 had skin disorders. Contents of the report: description of photographic chemicals used (CD-2, CD-3, ethylenediamine, formaldehyde, hydroquinone, potassium dichromate, etc.); handling of chemicals in the mixing, developing and analysis departments, and in the workshop; questionnaire survey, preliminary diagnosis, patch testing, examination of protective gloves and allergy tests on guinea pigs. CD-2, CD-3, methol and PBA-1 (persulfate bleach accelerator) caused allergic contact dermatitis in 12 cases. The colour developers CD-2 and CD-3 gave rise to lichenoid reactions in 2 cases. Proposals are made regarding preventive measures.","Occupational skin disease in a film laboratory Abs: Study carried out in a film developing laboratory employing 114 people of whom 43 had skin disorders. Contents of the report: description of photographic chemicals used (CD-2, CD-3, ethylenediamine, formaldehyde, hydroquinone, potassium dichromate, etc.); handling of chemicals in the mixing, developing and analysis departments, and in the workshop; questionnaire survey, preliminary diagnosis, patch testing, examination of protective gloves and allergy tests on guinea pigs. CD-2, CD-3, methol and PBA-1 (persulfate bleach accelerator) caused allergic contact dermatitis in 12 cases. The colour developers CD-2 and CD-3 gave rise to lichenoid reactions in 2 cases. Proposals are made regarding preventive measures."
1238997,Korallus and  Loenhoff 1981,Production and transformation of chromates - Experience in occupational medicine and epidemiology,"Roundup/survey of production, transformation and uses of chromates; analysis of the literature on toxicology, occupational medicine, medical supervision and epidemiology in this field. Zinc, strontium, and calcium chromates, and chromium (III) chromate, are considered to be carcinogens, whereas there is as yet no evidence of the carcinogenicity of chromium (IV) water-soluble compounds. There is a dminishing trend in the frequency of bronchial cancer in chromium production workers, due to more advanced health engineering and industrial hygiene. Classification of chromium compounds in TLV lists and in legislation currently in force in the Federal Republic of Germany.","Production and transformation of chromates - Experience in occupational medicine and epidemiology Abs: Roundup/survey of production, transformation and uses of chromates; analysis of the literature on toxicology, occupational medicine, medical supervision and epidemiology in this field. Zinc, strontium, and calcium chromates, and chromium (III) chromate, are considered to be carcinogens, whereas there is as yet no evidence of the carcinogenicity of chromium (IV) water-soluble compounds. There is a dminishing trend in the frequency of bronchial cancer in chromium production workers, due to more advanced health engineering and industrial hygiene. Classification of chromium compounds in TLV lists and in legislation currently in force in the Federal Republic of Germany."
1238992,Falcy et al. 1998,[Lead and its inorganic compounds],"Chemical safety information sheet. CD-ROM version of the document already analysed as CIS 99-1783. Acute toxicity: digestive disorders; haemolytic anaemia; cytologic hepatic damage; neurological effects (intracraneal hypertension and convulsive coma) which may leave sequelae. Chronic toxicity: haematological effects (anaemia); effects on the digestive tract (deposits of lead); neurological effects (convulsive coma, sensitive-motor neuropathy, amyotrophic lateral sclerosis); renal damage; high blood pressure; bone damage; effects on reproduction; carcinogenic effects (lung and stomach cancer). Exposure limits (France): 150µg/m<sup>3</sup> (mean value over 40 hours expressed as lead). EC number and mandatory labelling codes: No.231-100-4 (lead), No.082-001-00-6 (lead monoxide); T, R61, R62, R20/22, R33, S53, S45, 215-267-0 (lead monoxide). The complete datasheet collection on CD-ROM has been analysed under CIS 01-201.","[Lead and its inorganic compounds] Abs: Chemical safety information sheet. CD-ROM version of the document already analysed as CIS 99-1783. Acute toxicity: digestive disorders; haemolytic anaemia; cytologic hepatic damage; neurological effects (intracraneal hypertension and convulsive coma) which may leave sequelae. Chronic toxicity: haematological effects (anaemia); effects on the digestive tract (deposits of lead); neurological effects (convulsive coma, sensitive-motor neuropathy, amyotrophic lateral sclerosis); renal damage; high blood pressure; bone damage; effects on reproduction; carcinogenic effects (lung and stomach cancer). Exposure limits (France): 150µg/m<sup>3</sup> (mean value over 40 hours expressed as lead). EC number and mandatory labelling codes: No.231-100-4 (lead), No.082-001-00-6 (lead monoxide); T, R61, R62, R20/22, R33, S53, S45, 215-267-0 (lead monoxide). The complete datasheet collection on CD-ROM has been analysed under CIS 01-201."
1238986,Sognier et al. 1991,Uptake/persistence of chromium compounds in Chinese hamster V79 cells,,Uptake/persistence of chromium compounds in Chinese hamster V79 cells Abs: 
1238981,Aiyar et al. 1990,REACTION OF CHROMIUM(VI) WITH HYDROGEN PEROXIDE IN THE PRESENCE OF GLUTATHIONE: REACTIVE INTERMEDIATES AND RESULTING DNA DAMAGE,,REACTION OF CHROMIUM(VI) WITH HYDROGEN PEROXIDE IN THE PRESENCE OF GLUTATHIONE: REACTIVE INTERMEDIATES AND RESULTING DNA DAMAGE Abs: 
1238980,Reuzel et al. 1986,Carcinogenicity and in vitro genotoxicity of the particulate fraction of two stainless steel welding fumes,,Carcinogenicity and in vitro genotoxicity of the particulate fraction of two stainless steel welding fumes Abs: 
1238974,Metzler 1990,NEPHROCARCINOGENICITY OF ESTROGENS,,NEPHROCARCINOGENICITY OF ESTROGENS Abs: 
1238970,Dzhedzhelava et al. 1989,Induction of SOS functions in Escherichia coli cells exposed to action of chemical mutagens of various types,"On the basis of the SOS-chromotest which was developed by the authors earlier, the minimum time required for expression of the SOS-response is shown to be 15 min, the maximum being recorded 2 h later. An assay of induction of the SOS-response to the mutagens which act on DNA via various mechanisms (e. g., UV-irradiation, mitomycin C, nalidixic acid, nitroso-methylurea and acridine orange) revealed that all the mutagens under study caused induction of the SOS-response. Analysis of efficiency of SOS induction under the action of a mixture of formaldehyde with various amino acids has shown that arginine, asparagine and, especially, cysteine decrease the level of the SOS-response induction. This fact suggests an opportunity for using the SOS-chromotest not only to identify the mutagens and cancerogens, but also to screen the agents for their antimutagenic activity. The study of the SOS-response in the cells which are deficient in genes for repair and recombination has shown that induction is significantly suppressed in the mutants recA, lexA and recF; it is not modified in sbcB mutants and is significantly increased in the mutant lines recBC, uvrB and, particularly, in the double mutant recBCsbcB.","Induction of SOS functions in Escherichia coli cells exposed to action of chemical mutagens of various types Abs: On the basis of the SOS-chromotest which was developed by the authors earlier, the minimum time required for expression of the SOS-response is shown to be 15 min, the maximum being recorded 2 h later. An assay of induction of the SOS-response to the mutagens which act on DNA via various mechanisms (e. g., UV-irradiation, mitomycin C, nalidixic acid, nitroso-methylurea and acridine orange) revealed that all the mutagens under study caused induction of the SOS-response. Analysis of efficiency of SOS induction under the action of a mixture of formaldehyde with various amino acids has shown that arginine, asparagine and, especially, cysteine decrease the level of the SOS-response induction. This fact suggests an opportunity for using the SOS-chromotest not only to identify the mutagens and cancerogens, but also to screen the agents for their antimutagenic activity. The study of the SOS-response in the cells which are deficient in genes for repair and recombination has shown that induction is significantly suppressed in the mutants recA, lexA and recF; it is not modified in sbcB mutants and is significantly increased in the mutant lines recBC, uvrB and, particularly, in the double mutant recBCsbcB."
1238964,Balezin and  Saichenko 1988,CHARACTERISTICS OF COMBINED MUTAGENIC EFFECT OF CHROMIUM AND MANGANESE ON THE MICROBIC MUTATION MODELS,,CHARACTERISTICS OF COMBINED MUTAGENIC EFFECT OF CHROMIUM AND MANGANESE ON THE MICROBIC MUTATION MODELS Abs: 
1238960,Collaborative STUDY GROUP FOR THE and  Onucleus 1989,DIFFERENCE BETWEEN INTRAPERITONEAL AND ORAL GAVAGE APPLICATION IN THE MICRONUCLEUS TEST,,DIFFERENCE BETWEEN INTRAPERITONEAL AND ORAL GAVAGE APPLICATION IN THE MICRONUCLEUS TEST Abs: 
1238959,Norppa et al. 1989,AUTOMATION OF MOUSE BLOOD MICRONUCLEUS TEST BY FLOW CYTOMETRY,,AUTOMATION OF MOUSE BLOOD MICRONUCLEUS TEST BY FLOW CYTOMETRY Abs: 
1238954,Farrell et al. 1989,Chromium(V)-induced cleavage of DNA: Are chromium(V) complexes the active carcinogens in chromium(VI)-induced cancers?,,Chromium(V)-induced cleavage of DNA: Are chromium(V) complexes the active carcinogens in chromium(VI)-induced cancers? Abs: 
1238953,Hartwig and  Beyersmann 1989,"Mutagenicity, comutagenicity and inhibition of DNA repair of metal compounds in mammalian cells",,"Mutagenicity, comutagenicity and inhibition of DNA repair of metal compounds in mammalian cells Abs: "
1238948,Wakata et al. 1989,DIFFERENCE BETWEEN INTRAPERITONEAL AND ORAL GAVAGE APPLICATION IN THE MICRONUCLEUS TEST,,DIFFERENCE BETWEEN INTRAPERITONEAL AND ORAL GAVAGE APPLICATION IN THE MICRONUCLEUS TEST Abs: 
1238947,Hayashi et al. 1989,Flow cytometric micronucleus test with mouse bone marrow and peripheral blood erythrocytes,,Flow cytometric micronucleus test with mouse bone marrow and peripheral blood erythrocytes Abs: 
1238946,Elias et al. 1989,Solubilization of particulate chromium compounds and its relevance to cytotoxicity and morphological transformation of Syrian hamster embryo (she) cells,,Solubilization of particulate chromium compounds and its relevance to cytotoxicity and morphological transformation of Syrian hamster embryo (she) cells Abs: 
1238941,Sato and  Inui 1988,Mouse strain difference in the induction of micronuclei,,Mouse strain difference in the induction of micronuclei Abs: 
1238939,Myhr and  Caspary 1988,"Evaluation of the L5178Y mouse lymphoma cell mutagenesis assay: Intralaboratory results for sixty-three coded chemicals tested at Litton Bionetics, Inc","The reliability of the L5178Y TK+/- forward mutation assay as a rapid screen for genotoxicity was evaluated by testing 63 coded chemicals. Replicate treatments were used, and at least two independent experiments were performed for each test condition. The test conditions consisted of no exogenous activation, activation by Aroclor 1254-induced Fischer 344 rat liver S9 homogenate, and in some cases activation by noninduced Fischer 344 rat liver S9. The results were organized into tables that show the mutant colony counts, mutant frequency, and toxicity for each test chemical treatment, positive control treatment, and solvent negative control cultures. The repeat experiments were highly consistent and yielded contradictory evaluations for only a few of the chemicals studied. Fifty-one of the chemicals (81%) were evaluated as mutagenic under one or both of the test conditions. A range in minimum effective concentrations of almost 10(6)-fold (0.008 to 5,000 micrograms/ml) was observed among the mutagenic chemicals. Nine chemicals (14%) were considered to be nonmutagenic. Three chemicals (progesterone, p-rosaniline HCl, and 1,1,1-trichloroethane) gave responses that were not easily evaluated under any test condition: evidence for mutagenesis was obtained in some experiments but not for all repeat studies. Under nonactivation conditions, specifically, the mutagenic activities of 4,4'-bis(dimethylamino)benzophenone, progesterone, and p-rosaniline HCl remained uncertain. With S9 activation, uncertain evidence for mutagenesis was obtained for 2-naphthylamine, progesterone, and 1,1,1-trichloroethane. In some cases, changes in the treatment conditions could lead to different evaluations of the mutagenic activity, and these possibilities are discussed in the descriptive evaluations of each chemical. Comparisons of the observed responses with published results were possible for 29 of the compounds and yielded highly confirmatory evaluations.","Evaluation of the L5178Y mouse lymphoma cell mutagenesis assay: Intralaboratory results for sixty-three coded chemicals tested at Litton Bionetics, Inc Abs: The reliability of the L5178Y TK+/- forward mutation assay as a rapid screen for genotoxicity was evaluated by testing 63 coded chemicals. Replicate treatments were used, and at least two independent experiments were performed for each test condition. The test conditions consisted of no exogenous activation, activation by Aroclor 1254-induced Fischer 344 rat liver S9 homogenate, and in some cases activation by noninduced Fischer 344 rat liver S9. The results were organized into tables that show the mutant colony counts, mutant frequency, and toxicity for each test chemical treatment, positive control treatment, and solvent negative control cultures. The repeat experiments were highly consistent and yielded contradictory evaluations for only a few of the chemicals studied. Fifty-one of the chemicals (81%) were evaluated as mutagenic under one or both of the test conditions. A range in minimum effective concentrations of almost 10(6)-fold (0.008 to 5,000 micrograms/ml) was observed among the mutagenic chemicals. Nine chemicals (14%) were considered to be nonmutagenic. Three chemicals (progesterone, p-rosaniline HCl, and 1,1,1-trichloroethane) gave responses that were not easily evaluated under any test condition: evidence for mutagenesis was obtained in some experiments but not for all repeat studies. Under nonactivation conditions, specifically, the mutagenic activities of 4,4'-bis(dimethylamino)benzophenone, progesterone, and p-rosaniline HCl remained uncertain. With S9 activation, uncertain evidence for mutagenesis was obtained for 2-naphthylamine, progesterone, and 1,1,1-trichloroethane. In some cases, changes in the treatment conditions could lead to different evaluations of the mutagenic activity, and these possibilities are discussed in the descriptive evaluations of each chemical. Comparisons of the observed responses with published results were possible for 29 of the compounds and yielded highly confirmatory evaluations."
1238937,Hooftman et al. 1988,The in vitro cytotoxicity and genotoxicity of welding fumes,,The in vitro cytotoxicity and genotoxicity of welding fumes Abs: 
1238936,Venier et al. 1988,VALIDATION OF SOS CHROMOTEST WITH CHEMICAL COMPOUNDS AND BIOLOGICAL SAMPLES,,VALIDATION OF SOS CHROMOTEST WITH CHEMICAL COMPOUNDS AND BIOLOGICAL SAMPLES Abs: 
1238934,Sugiyama 1987,CHARACTERIZATION OF DNA LESIONS INDUCED BY CALCIUM CHROMATE,,CHARACTERIZATION OF DNA LESIONS INDUCED BY CALCIUM CHROMATE Abs: 
1238933,Snyder 1988,Role of active oxygen species in metal-induced DNA strand breakage in human diploid fibroblasts,"The ability of 6 metal salts to induce DNA damage in human diploid fibroblasts was examined. Cadmium, magnesium, manganese, chromium(VI), zinc and selenite were all shown to induce DNA strand breaks as measured by two independent assays. DNA strand breaks were repaired within 2-4 h after removal of metal and this repair appeared not to be sensitive to &quot;long-patch&quot; repair inhibitors. With the exception of selenite, metal-induced DNA damage appeared to be mediated via the formation of active oxygen species since oxygen scavengers when administered simultaneously with the metal, antagonized strand break formation. Selenite-induced DNA damage (as previously reported) was dependent on the formation of a selenite-glutathione conjugant and was not affected by oxygen radical scavengers. Scavenger treatment did not enhance cloning ability of metal-treated cells suggesting that DNA strand breaks may not be important in metal-induced cytotoxicity.","Role of active oxygen species in metal-induced DNA strand breakage in human diploid fibroblasts Abs: The ability of 6 metal salts to induce DNA damage in human diploid fibroblasts was examined. Cadmium, magnesium, manganese, chromium(VI), zinc and selenite were all shown to induce DNA strand breaks as measured by two independent assays. DNA strand breaks were repaired within 2-4 h after removal of metal and this repair appeared not to be sensitive to &quot;long-patch&quot; repair inhibitors. With the exception of selenite, metal-induced DNA damage appeared to be mediated via the formation of active oxygen species since oxygen scavengers when administered simultaneously with the metal, antagonized strand break formation. Selenite-induced DNA damage (as previously reported) was dependent on the formation of a selenite-glutathione conjugant and was not affected by oxygen radical scavengers. Scavenger treatment did not enhance cloning ability of metal-treated cells suggesting that DNA strand breaks may not be important in metal-induced cytotoxicity."
1238928,Zeiger et al. 1988,SALMONELLA MUTAGENICITY TESTS. 4.RESULTS FROM THE TESTING OF 300 CHEMICALS,,SALMONELLA MUTAGENICITY TESTS. 4.RESULTS FROM THE TESTING OF 300 CHEMICALS Abs: 
1238909,Hamilton and  Wetterhahn 1986,Chromium (VI)-induced DNA damage in chick embryo liver and blood cells in vivo,"Uptake of chromium (VI) and subsequent induction of DNA damage was examined in liver and blood cells of 14-day chick embryos after injection of sodium dichromate onto the inner shell membrane. Maximal loss of chromium from the inner shell membrane and distribution of chromium in liver, lung and blood was observed 2 h after injection. DNA strand breaks, interstrand cross-links and DNA--protein cross-links were measured using the alkaline elution technique. In chick embryo liver, chromium (VI) induced DNA cross-links in the absence of strand breaks. Maximal DNA cross-linking was detected in the liver 8 h after injection. Little or no DNA damage remained in the liver 10-24 h after injection. In contrast, chromium (VI) induced DNA strand breaks in the absence of cross-links in chick embryo blood cells. Maximal DNA strand breakage was observed in blood cells 8 h after injection. High levels of DNA strand breaks were present in blood cells even 24 h after treatment. These intra-embryonic tissue differences in chromium (VI)-induced DNA damage may be a result of the differences in glutathione, cytochrome P-450, other pathways of chromium (VI) metabolism or chromatin organization which exist in liver and blood cells.","Chromium (VI)-induced DNA damage in chick embryo liver and blood cells in vivo Abs: Uptake of chromium (VI) and subsequent induction of DNA damage was examined in liver and blood cells of 14-day chick embryos after injection of sodium dichromate onto the inner shell membrane. Maximal loss of chromium from the inner shell membrane and distribution of chromium in liver, lung and blood was observed 2 h after injection. DNA strand breaks, interstrand cross-links and DNA--protein cross-links were measured using the alkaline elution technique. In chick embryo liver, chromium (VI) induced DNA cross-links in the absence of strand breaks. Maximal DNA cross-linking was detected in the liver 8 h after injection. Little or no DNA damage remained in the liver 10-24 h after injection. In contrast, chromium (VI) induced DNA strand breaks in the absence of cross-links in chick embryo blood cells. Maximal DNA strand breakage was observed in blood cells 8 h after injection. High levels of DNA strand breaks were present in blood cells even 24 h after treatment. These intra-embryonic tissue differences in chromium (VI)-induced DNA damage may be a result of the differences in glutathione, cytochrome P-450, other pathways of chromium (VI) metabolism or chromatin organization which exist in liver and blood cells."
1238906,Chang 1985,Cytokinetic effect and cytotoxic action of chromium compound on human fibroblast in culture,"Chromium is ubiquitous in nature, ranking fifteenth in the body of man. Chromium has been reported to be an environmental carcinogen. In The U.S., the use of chromium is mainly divided as follows: (1) metallurgical industries - 57%; (2) refractory materials - 30%; and (3) Chemistry Industry - 13%. The metabolism and toxicity of chromium has recently been described by D. Burrows (1983). Chromium compounds have been suspected as human carcinogens since 1932, but which compounds are the most potent carcinogens has not been known. Trivalent chromium compounds are not thought to increase incidence of lung cancer in man (Burrows 1983). Most animal studies have been carried out with hexavalent compounds. Attempts to produce bronchogenic carcinoma in mice by exposure to Chromates in inhalation chambers had been unsuccessful (Steffes and Baetjer 1965; Nettesheim et al. 1971). Some increase in pulmonary adenomas was observed in those studies. When calcium Chromate was implanted intrabronchially in rats by Laskin et al. (1970), a number of squamous carcinoma were induced in the lungs. Mutagenicity of chromium has been demonstrated in various prokaryotic systems (Petrilli et al. 1982). All hexavalent compounds are mutagenic, but not trivalent compounds. Cellular transformation by chromium (VI) compounds has been shown in rodent cells (Fradkin et al. 1975; Tsuda and Kato 1977). Clastogenic effect of chromium compounds has been demonstrated as induction of sister chromatic exchange and chromosomal aberration in mammalian cells (Tsuda and Kato 1977; Rainaldi et al. 1982; Bianchi et al. 1983).","Cytokinetic effect and cytotoxic action of chromium compound on human fibroblast in culture Abs: Chromium is ubiquitous in nature, ranking fifteenth in the body of man. Chromium has been reported to be an environmental carcinogen. In The U.S., the use of chromium is mainly divided as follows: (1) metallurgical industries - 57%; (2) refractory materials - 30%; and (3) Chemistry Industry - 13%. The metabolism and toxicity of chromium has recently been described by D. Burrows (1983). Chromium compounds have been suspected as human carcinogens since 1932, but which compounds are the most potent carcinogens has not been known. Trivalent chromium compounds are not thought to increase incidence of lung cancer in man (Burrows 1983). Most animal studies have been carried out with hexavalent compounds. Attempts to produce bronchogenic carcinoma in mice by exposure to Chromates in inhalation chambers had been unsuccessful (Steffes and Baetjer 1965; Nettesheim et al. 1971). Some increase in pulmonary adenomas was observed in those studies. When calcium Chromate was implanted intrabronchially in rats by Laskin et al. (1970), a number of squamous carcinoma were induced in the lungs. Mutagenicity of chromium has been demonstrated in various prokaryotic systems (Petrilli et al. 1982). All hexavalent compounds are mutagenic, but not trivalent compounds. Cellular transformation by chromium (VI) compounds has been shown in rodent cells (Fradkin et al. 1975; Tsuda and Kato 1977). Clastogenic effect of chromium compounds has been demonstrated as induction of sister chromatic exchange and chromosomal aberration in mammalian cells (Tsuda and Kato 1977; Rainaldi et al. 1982; Bianchi et al. 1983)."
1238903,Kaths 1981,"IN VIVO CYTOGENETIC EFFECT OF SOME SALTS OF THE HEAVY METALS CADMIUM, CHROMIUM,MERCURY, AND PLATINUM IN ASSAYS OF MICRONUCLEI AND SISTER CHROMATID EXCHANGE",,"IN VIVO CYTOGENETIC EFFECT OF SOME SALTS OF THE HEAVY METALS CADMIUM, CHROMIUM,MERCURY, AND PLATINUM IN ASSAYS OF MICRONUCLEI AND SISTER CHROMATID EXCHANGE Abs: "
1238897,Kirsch-Volders and  Nijs 1986,INDUCTION OF ABNORMAL MITOTIC FIGURES BY CARCINOGENS IN HUMAN DIPLOID FIBROBLASTS,,INDUCTION OF ABNORMAL MITOTIC FIGURES BY CARCINOGENS IN HUMAN DIPLOID FIBROBLASTS Abs: 
1238895,Milo and  Casto 1986,CONDITIONS FOR TRANSFORMATION OF HUMAN FIBROBLAST CELLS: AN OVERVIEW,,CONDITIONS FOR TRANSFORMATION OF HUMAN FIBROBLAST CELLS: AN OVERVIEW Abs: 
1238893,Rossman and  Molina 1986,The genetic toxicology of metal compounds: II. Enhancement of ultraviolet light-induced mutagenesis in Escherichia coli WP2,"Salts of metals which are carcinogenic, noncarcinogenic, or of unknown carcinogenicity were assayed for their abilities to modulate ultraviolet (UV)-induced mutagenesis in Escherichia coli WP2. In addition to the previously reported comutagenic effect of arsenite, salts of three other compounds were found to enhance UV mutagenesis. CuCl2, MnCl2 (and a small effect by KMnO4), and NaMoO4 acted as comutagens in E coli WP2, which has wild-type DNA repair capability, but were much less comutagenic in the repair deficient strain WP2s (uvrA). The survival of irradiated or unirradiated cells was not affected by these compounds. No effects on UV mutagenesis were seen for 16 other metal compounds. We suggest that the comutagenic effects might occur either via metal-induced decreases in the fidelity of repair replication or (in the case of CuCl2) via metal-induced depurination.","The genetic toxicology of metal compounds: II. Enhancement of ultraviolet light-induced mutagenesis in Escherichia coli WP2 Abs: Salts of metals which are carcinogenic, noncarcinogenic, or of unknown carcinogenicity were assayed for their abilities to modulate ultraviolet (UV)-induced mutagenesis in Escherichia coli WP2. In addition to the previously reported comutagenic effect of arsenite, salts of three other compounds were found to enhance UV mutagenesis. CuCl2, MnCl2 (and a small effect by KMnO4), and NaMoO4 acted as comutagens in E coli WP2, which has wild-type DNA repair capability, but were much less comutagenic in the repair deficient strain WP2s (uvrA). The survival of irradiated or unirradiated cells was not affected by these compounds. No effects on UV mutagenesis were seen for 16 other metal compounds. We suggest that the comutagenic effects might occur either via metal-induced decreases in the fidelity of repair replication or (in the case of CuCl2) via metal-induced depurination."
1238892,Majone et al. 1982,Chromium-induced sister chromatid exchanges in CHO cells,,Chromium-induced sister chromatid exchanges in CHO cells Abs: 
1238883,Smirnov 1985,LATE EFFECTS OF WATER-CONTAINED SIX- AND THREE-VALENT CHROMIUM ON THE BODY,,LATE EFFECTS OF WATER-CONTAINED SIX- AND THREE-VALENT CHROMIUM ON THE BODY Abs: 
1238882,Rudnykh 1985,In vivo and in vitro DNA-repair synthesis under the influence of chromium compounds in human lymphocytes,,In vivo and in vitro DNA-repair synthesis under the influence of chromium compounds in human lymphocytes Abs: 
1238878,Oda et al. 1985,EVALUATION OF THE NEW SYSTEM (UMU-TEST) FOR THE DETECTION OF ENVIRONMENTAL MUTAGENS AND CARCINOGENS,,EVALUATION OF THE NEW SYSTEM (UMU-TEST) FOR THE DETECTION OF ENVIRONMENTAL MUTAGENS AND CARCINOGENS Abs: 
1238866,Tong et al. 1985,"EVALUATION OF GENOTOXICITY OF BERYLLIUM, CADMIUM, CHROMIUM, AND NICKEL IN AN INVITRO BATTERY",,"EVALUATION OF GENOTOXICITY OF BERYLLIUM, CADMIUM, CHROMIUM, AND NICKEL IN AN INVITRO BATTERY Abs: "
1238865,Levis et al. 1983,NITRILOTRIACETIC ACID (NTA) ENHANCES THE MUTAGENICITY OF METALS,,NITRILOTRIACETIC ACID (NTA) ENHANCES THE MUTAGENICITY OF METALS Abs: 
1238864,Lavelle 1985,MECHANISMS OF CHROMIUM GENOTOXICITY: POTENTIATION OF AZIDE-INDUCED MUTAGENESIS,,MECHANISMS OF CHROMIUM GENOTOXICITY: POTENTIATION OF AZIDE-INDUCED MUTAGENESIS Abs: 
1238863,Garland et al. 1985,"Comparative mutagenic efficiency of CrVI and CrIII in reverting GC VS AT in the salmonella strains TA97, 100, 102, 103, 104 and 2638",,"Comparative mutagenic efficiency of CrVI and CrIII in reverting GC VS AT in the salmonella strains TA97, 100, 102, 103, 104 and 2638 Abs: "
1238862,Dunkel et al. 1984,Reproducibility of microbial mutagenicity assays. 1. Tests with salmonella typhimurium and escherichia coli using a standardized protocol,,Reproducibility of microbial mutagenicity assays. 1. Tests with salmonella typhimurium and escherichia coli using a standardized protocol Abs: 
1238858,De Flora et al. 1984,Distinctive mechanisms for interaction of hexavalent and trivalent chromium with DNA?,"Genotoxicity patterns observed in mutagenicity and DNA?repair tests in bacteria suggest distinctive mechanisms for the interaction of chromium(VI) and chromium(III) with DNA. This is in agreement with physico?chemical data, indicating that chromium(III) induces DNA?protein and DNA?DNA cross?links and decreases the fidelity of DNA replication, while chromium(VI) unbalances nucleotide pools and, due to its oxidizing power, induces single?strand breaks in DNA.","Distinctive mechanisms for interaction of hexavalent and trivalent chromium with DNA? Abs: Genotoxicity patterns observed in mutagenicity and DNA?repair tests in bacteria suggest distinctive mechanisms for the interaction of chromium(VI) and chromium(III) with DNA. This is in agreement with physico?chemical data, indicating that chromium(III) induces DNA?protein and DNA?DNA cross?links and decreases the fidelity of DNA replication, while chromium(VI) unbalances nucleotide pools and, due to its oxidizing power, induces single?strand breaks in DNA."
1238857,Bianchi et al. 1984,TRIVALENT CHROMIUM IS NEITHER CYTOTOXIC NOR MUTAGENIC IN PERMEABILIZED HAMSTER FIBROBLASTS,,TRIVALENT CHROMIUM IS NEITHER CYTOTOXIC NOR MUTAGENIC IN PERMEABILIZED HAMSTER FIBROBLASTS Abs: 
1238855,Kalinina and  Minseitova 1983,MUTAGENIC EFFECTS AND DNA-DAMAGING ACTION IN ESCHERICHIA COLI CELLS TREATED WITH POTASSIUM BICHROMATE,,MUTAGENIC EFFECTS AND DNA-DAMAGING ACTION IN ESCHERICHIA COLI CELLS TREATED WITH POTASSIUM BICHROMATE Abs: 
1238854,Kalinina and  Minseitova 1983,DNA repair pathways in Escherichia coli K-12 cells after mutation induction by potassium dichromate,,DNA repair pathways in Escherichia coli K-12 cells after mutation induction by potassium dichromate Abs: 
1238850,Cohen et al. 1983,Chemical clastogenicity in lymphoid cell lines of chromosomal instability syndromes,"Long-term lymphoid cell lines (LCL) derived from normal individuals, patients with ataxia telangiectasia (A-T), xeroderma pigmentosum (XP), and Fanconi anemia (FA) were exposed to various concentrations of 11 chemical clastogens. The agents were chosen to represent a variety of suggested modes of action. In contrast to all other genotypes, the FA lines demonstrated significant rates of spontaneous chromosomal breakage and showed hypersensitivity to all of the clastogens employed. Variability among lines within a genotype suggested individual responses to specific agents. Computation of ""corrected values"" to address the problem of baseline disparity removed some of the significant differences between the FA and other lines. Nonetheless, following correction, the FA genotype was still delineated by clastogens which are not DNA cross-linkers. The A-T lines were specifically identified by the induction of chromosome damage by bleomycin and neocarzinostatin.","Chemical clastogenicity in lymphoid cell lines of chromosomal instability syndromes Abs: Long-term lymphoid cell lines (LCL) derived from normal individuals, patients with ataxia telangiectasia (A-T), xeroderma pigmentosum (XP), and Fanconi anemia (FA) were exposed to various concentrations of 11 chemical clastogens. The agents were chosen to represent a variety of suggested modes of action. In contrast to all other genotypes, the FA lines demonstrated significant rates of spontaneous chromosomal breakage and showed hypersensitivity to all of the clastogens employed. Variability among lines within a genotype suggested individual responses to specific agents. Computation of ""corrected values"" to address the problem of baseline disparity removed some of the significant differences between the FA and other lines. Nonetheless, following correction, the FA genotype was still delineated by clastogens which are not DNA cross-linkers. The A-T lines were specifically identified by the induction of chromosome damage by bleomycin and neocarzinostatin."
1238847,Siebert 1982,FURTHER IMPROVEMENT OF GENETIC AND CYTOGENETIC TEST PATTERN WITH INCREASED RELEVANCE PREDICTING CARCINOGENIC AND PHARMACOLOGICAL EFFECTS,,FURTHER IMPROVEMENT OF GENETIC AND CYTOGENETIC TEST PATTERN WITH INCREASED RELEVANCE PREDICTING CARCINOGENIC AND PHARMACOLOGICAL EFFECTS Abs: 
1238845,Iijima et al. 1982,DEVELOPMENTAL AND CYTOGENETIC EFFECTS OF POTASSIUM DICHROMATE ON MOUSE EMBRYOS IN VITRO,,DEVELOPMENTAL AND CYTOGENETIC EFFECTS OF POTASSIUM DICHROMATE ON MOUSE EMBRYOS IN VITRO Abs: 
1238842,Pashin and  Toroptsev 1983,Induction of micronuclei in mouse erythrocytes by Cr6+,,Induction of micronuclei in mouse erythrocytes by Cr6+ Abs: 
1238837,Elias et al. 1984,"Cytotoxic, clastogenic and morphological transforming effects of chromic oxide on mammalian cells in vitro",,"Cytotoxic, clastogenic and morphological transforming effects of chromic oxide on mammalian cells in vitro Abs: "
1238834,Hayes et al. 1984,RK bacterial test for independently measuring chemical toxicity and mutagenicity: Short-term forward selection assay,"A short-term bacterial assay system for determining the mutagenic potential of environmental substances was developed and validated. Genotoxic activity was demonstrated for selected substances from 10 categories of chemical agents. The RK test results were obtained with one Escherichia coli assay strain that was transiently exposed to, and then removed from the test substance prior to the selection step for mutant cells. The RK test employs a hitherto unused short-term assay technique for selecting forward mutations in the wild-type selector strain cells. The cells of the selector strain are killed upon shifting to 42 degrees C as a consequence of thermal derepression and subsequent expression of the replication genes from an integrated 10-kilobase fragment of phage lambda. Cells that acquire mutations in the responsible killing genes are detected by their colony-forming ability at 42 degrees C. A substance is determined to be genotoxic if it is capable of increasing the forward mutation frequency for appearance of these mutant cells. Toxicity of the agent is independently evaluated by examining its effect on the viability of the selector strain at 30 degrees C, when the viral replication genes remain repressed. The flexible assay protocol enables determination of the effect of pH on mutagenic activity, the requirement for metabolic activation, and assays of nearly insoluble or highly toxic substances.","RK bacterial test for independently measuring chemical toxicity and mutagenicity: Short-term forward selection assay Abs: A short-term bacterial assay system for determining the mutagenic potential of environmental substances was developed and validated. Genotoxic activity was demonstrated for selected substances from 10 categories of chemical agents. The RK test results were obtained with one Escherichia coli assay strain that was transiently exposed to, and then removed from the test substance prior to the selection step for mutant cells. The RK test employs a hitherto unused short-term assay technique for selecting forward mutations in the wild-type selector strain cells. The cells of the selector strain are killed upon shifting to 42 degrees C as a consequence of thermal derepression and subsequent expression of the replication genes from an integrated 10-kilobase fragment of phage lambda. Cells that acquire mutations in the responsible killing genes are detected by their colony-forming ability at 42 degrees C. A substance is determined to be genotoxic if it is capable of increasing the forward mutation frequency for appearance of these mutant cells. Toxicity of the agent is independently evaluated by examining its effect on the viability of the selector strain at 30 degrees C, when the viral replication genes remain repressed. The flexible assay protocol enables determination of the effect of pH on mutagenic activity, the requirement for metabolic activation, and assays of nearly insoluble or highly toxic substances."
1238832,Parodi et al. 1983,Quantitative predictivity of the transformation in vitro assay compared with the Ames test,"For 59 chemical compounds, we have found homogeneous data on transformation in vitro, mutagenicity in the Ames test, and carcinogenicity. We have compared the potency in inducing transformation in vitro in hamster fibroblast cells with the carcinogenic potency and found a modest correlation coefficient between the two parameters (r = 0.37). For these same 59 compounds it was also possible to compare mutagenic potency in the Ames test with carcinogenic potency. The correlation level was very similar (r = 0.34). The predictivity of transformation in vitro increased significantly when only compounds for which some kind of dose-response relationship was available were utilized (r = 0.65). This result stresses the importance of the quantitative aspect of the response in predictivity studies. The present study is compared with previous studies on the quantitative predictivity of different short-term tests. Our work is not definitive, but gives an idea of the possible type of approach to the problem of comparing quantitative predictivities.","Quantitative predictivity of the transformation in vitro assay compared with the Ames test Abs: For 59 chemical compounds, we have found homogeneous data on transformation in vitro, mutagenicity in the Ames test, and carcinogenicity. We have compared the potency in inducing transformation in vitro in hamster fibroblast cells with the carcinogenic potency and found a modest correlation coefficient between the two parameters (r = 0.37). For these same 59 compounds it was also possible to compare mutagenic potency in the Ames test with carcinogenic potency. The correlation level was very similar (r = 0.34). The predictivity of transformation in vitro increased significantly when only compounds for which some kind of dose-response relationship was available were utilized (r = 0.65). This result stresses the importance of the quantitative aspect of the response in predictivity studies. The present study is compared with previous studies on the quantitative predictivity of different short-term tests. Our work is not definitive, but gives an idea of the possible type of approach to the problem of comparing quantitative predictivities."
1238827,Gomez-Arroyo and  Villalobos-Pietrini 1983,Chromosomal alterations induced by some chromium salts,,Chromosomal alterations induced by some chromium salts Abs: 
1238823,Zakour et al. 1983,Metal-induced mutagenesis in the LACI gene of escherichia coli,,Metal-induced mutagenesis in the LACI gene of escherichia coli Abs: 
1238819,Pashin et al. 1982,Dominant lethals induced in male mice by low dose of potassium dichromate,,Dominant lethals induced in male mice by low dose of potassium dichromate Abs: 
1238813,Parodi et al. 1982,"Alkaline elution in vivo: Fluorometric analysis in rats. Quantitative predictivity of carcinogenicity, as compared with other short-term tests",,"Alkaline elution in vivo: Fluorometric analysis in rats. Quantitative predictivity of carcinogenicity, as compared with other short-term tests Abs: "
1238812,Majone et al. 1981,Induction of sister chromatid exchanges in mouse lymphocytes: Interactions between leukemogenic viruses and chemical carcinogens,,Induction of sister chromatid exchanges in mouse lymphocytes: Interactions between leukemogenic viruses and chemical carcinogens Abs: 
1238810,Warren 1980,Detection of genetically toxic metals by a microtiter microbial DNA repair assay,"For some years, our laboratory has been involved in assessing the genetically toxic effects of inorganic chemicals found in the environment near mining and smelting operations (Tindall et al., 1978; Warren et al., 1979) and of metal-containing pesticides used in Montana (Warren et al., 1976). Although many inorganic species are known or suspected carcinogens or are genetically active in many test systems (Flessel et al., 1979; Sunderman, 1978), most existing short-term biological screening methods are unsuitable for use with this class of suspected carcinogen. Only two systems, the Bacillus subtilus rec assay (Nishioka, 1975; Kanematsu et al., 1980) and an in vitro DNA synthesis fidelity assay (Loeb et al., 1979), have been useful for a large number of inorganic chemicals. Mutagenicity of some inorganic chemicals has been demonstrated in a CHO/HGPRT assay (Hsie et al., 1979) with considerable technical difficulty due to the general toxicity of inorganic chemicals. Green and Muriel (1976) have used a repair-deficient series of Escherichia coli B strains to detect mutagenicity of some chromate salts; also by this method, they found that nickel chloride salts do not cause differential lethality.","Detection of genetically toxic metals by a microtiter microbial DNA repair assay Abs: For some years, our laboratory has been involved in assessing the genetically toxic effects of inorganic chemicals found in the environment near mining and smelting operations (Tindall et al., 1978; Warren et al., 1979) and of metal-containing pesticides used in Montana (Warren et al., 1976). Although many inorganic species are known or suspected carcinogens or are genetically active in many test systems (Flessel et al., 1979; Sunderman, 1978), most existing short-term biological screening methods are unsuitable for use with this class of suspected carcinogen. Only two systems, the Bacillus subtilus rec assay (Nishioka, 1975; Kanematsu et al., 1980) and an in vitro DNA synthesis fidelity assay (Loeb et al., 1979), have been useful for a large number of inorganic chemicals. Mutagenicity of some inorganic chemicals has been demonstrated in a CHO/HGPRT assay (Hsie et al., 1979) with considerable technical difficulty due to the general toxicity of inorganic chemicals. Green and Muriel (1976) have used a repair-deficient series of Escherichia coli B strains to detect mutagenicity of some chromate salts; also by this method, they found that nickel chloride salts do not cause differential lethality."
1238808,Mclean et al. 1983,THE EFFECT OF STANNOUS AND STANNIC (TIN) CHLORIDE ON DNA IN CHINESE HAMSTER OVARY CELLS,,THE EFFECT OF STANNOUS AND STANNIC (TIN) CHLORIDE ON DNA IN CHINESE HAMSTER OVARY CELLS Abs: 
1238801,Pashin et al. 1981,Kompleksnoe ispytanie geneticheskoi? aktivnosti shestivalentnogo iona khroma in vitro i in vivo,,Kompleksnoe ispytanie geneticheskoi? aktivnosti shestivalentnogo iona khroma in vitro i in vivo Abs: 
1238799,Siebert 1981,"FURTHER IMPROVEMENT OF A GENETIC PRESCREENING TEST PATTERN FOR CARCINOGENIC EFFECTS OF ENVIRONMENTAL CHEMICALS, IN: GENETIC EFFECTS OF ENVIRONMENTAL CHEMICALS",,"FURTHER IMPROVEMENT OF A GENETIC PRESCREENING TEST PATTERN FOR CARCINOGENIC EFFECTS OF ENVIRONMENTAL CHEMICALS, IN: GENETIC EFFECTS OF ENVIRONMENTAL CHEMICALS Abs: "
1238798,Robison et al. 1982,Strand breakage and decreased molecular weight of DNA induced by specific metal compounds,"The effect of various metal compounds on the DNA of Chinese hamster ovary (CHO) cells was studied. Both NiCl2 and crystalline NiS caused DNA strand breaks in cultured CHO cells, whereas amorphous NiS did not. Strand breaks were quantitated by determining the number average molecular weight of DNA following treatment with the metal compounds. Exposure of cells to crystalline NiS, CoS, CdS, AgS, CuS and Ni3S2 at 10 ?g/ml for 24 h also induced DNA strand breaks. Similar exposure to activated charcoal, which was also actively phagocytosed, failed to cause any effect on the DNA of CHO cells. In the case of NiCl2 and NiS the effect was shown to be both time and dose dependent. Other soluble metal compounds such as HgCl2, CaCrO4, and CdCl2 also decreased the molecular weight of DNA while MnCl2, ZnCl2 and FeCl2 caused no significantly detectable change in DNA molecular weight. These effects, which occur at low metal concentrations suggest that nickel and other metals which cause cellular transformation have a very selective and specific effect upon DNA.","Strand breakage and decreased molecular weight of DNA induced by specific metal compounds Abs: The effect of various metal compounds on the DNA of Chinese hamster ovary (CHO) cells was studied. Both NiCl2 and crystalline NiS caused DNA strand breaks in cultured CHO cells, whereas amorphous NiS did not. Strand breaks were quantitated by determining the number average molecular weight of DNA following treatment with the metal compounds. Exposure of cells to crystalline NiS, CoS, CdS, AgS, CuS and Ni3S2 at 10 ?g/ml for 24 h also induced DNA strand breaks. Similar exposure to activated charcoal, which was also actively phagocytosed, failed to cause any effect on the DNA of CHO cells. In the case of NiCl2 and NiS the effect was shown to be both time and dose dependent. Other soluble metal compounds such as HgCl2, CaCrO4, and CdCl2 also decreased the molecular weight of DNA while MnCl2, ZnCl2 and FeCl2 caused no significantly detectable change in DNA molecular weight. These effects, which occur at low metal concentrations suggest that nickel and other metals which cause cellular transformation have a very selective and specific effect upon DNA."
1238796,Imreh and  Radulescu 1982,Cytogenetic effects of chromium in vivo and in vitro,,Cytogenetic effects of chromium in vivo and in vitro Abs: 
1238789,Bianchi et al. 1982,SCINTILLOMETRIC DETERMINATION OF DNA REPAIR IN HUMAN CELL LINES: A CRITICAL APPRAISAL,,SCINTILLOMETRIC DETERMINATION OF DNA REPAIR IN HUMAN CELL LINES: A CRITICAL APPRAISAL Abs: 
1238783,Tindall and  Hsie 1980,Mutagenic and cytotoxic effects of hexavalent and trivalent chromium in the cho/hgprt system,"Treatment with the oxidized form of chromium, Cr(V1) as K2Cr04, produced a concentration-dependent increase in mutation induction at the hypo-xanthine-guanine phosphoribosyl transferase (HGPRT) locus in Chinese hamster ovary (CHO) cells as determined by the frequency of 6-thioguanine resistant (TGr) mutants. Cr(V1) showed a concentration-dependent increase in mutagenicity over a range of 0.25-2.0 ?g/ml. Typical results of a 5 hour treatment with Cr(VI) induced a maximum of 75 TGr mutants/106 clonable cells at approximately 20% cloning efficiency; the spontaneous mutation frequency is generally 0-10 mutants/106 cells. We observed a decline, rather than an increase, of mutation frequency when treatment at Cr(V1) concentrations caused a reduction of cellular reproductive capacity greater than 80-90%. However, the reduced form of chromium, Cr(III) as Cr(CH3C00)3, did not exhibit notable mutagenicity or cytotoxicity at concentrations to 20 ?g/ml. While we presume the ultimate cellular form of chromium is the trivalent species, mutation induction by chromium seems to be sensitively modified by the initial oxidation state and by the cellular growth conditions during treatment. At Cr (VI) concentrations which inhibit cell growth and presumably DNA synthesis, mutation induction is lowered or not demonstrable. This may be consistent with the notion that metal mediated enhancement of DNA replicative errors accounts for one mechanism of metal mutagenesis. (Research supported jointly by EPA under Interagency Agreement D8-E681-AO and by DOE under contract W-7405-eng-26 with the Union Carbide Corp.)","Mutagenic and cytotoxic effects of hexavalent and trivalent chromium in the cho/hgprt system Abs: Treatment with the oxidized form of chromium, Cr(V1) as K2Cr04, produced a concentration-dependent increase in mutation induction at the hypo-xanthine-guanine phosphoribosyl transferase (HGPRT) locus in Chinese hamster ovary (CHO) cells as determined by the frequency of 6-thioguanine resistant (TGr) mutants. Cr(V1) showed a concentration-dependent increase in mutagenicity over a range of 0.25-2.0 ?g/ml. Typical results of a 5 hour treatment with Cr(VI) induced a maximum of 75 TGr mutants/106 clonable cells at approximately 20% cloning efficiency; the spontaneous mutation frequency is generally 0-10 mutants/106 cells. We observed a decline, rather than an increase, of mutation frequency when treatment at Cr(V1) concentrations caused a reduction of cellular reproductive capacity greater than 80-90%. However, the reduced form of chromium, Cr(III) as Cr(CH3C00)3, did not exhibit notable mutagenicity or cytotoxicity at concentrations to 20 ?g/ml. While we presume the ultimate cellular form of chromium is the trivalent species, mutation induction by chromium seems to be sensitively modified by the initial oxidation state and by the cellular growth conditions during treatment. At Cr (VI) concentrations which inhibit cell growth and presumably DNA synthesis, mutation induction is lowered or not demonstrable. This may be consistent with the notion that metal mediated enhancement of DNA replicative errors accounts for one mechanism of metal mutagenesis. (Research supported jointly by EPA under Interagency Agreement D8-E681-AO and by DOE under contract W-7405-eng-26 with the Union Carbide Corp.)"
1238775,Otto and  Oldiges 1980,Flow cytogenetic studies in chromosomes and whole cells for the detection of clastogenic effects,"Flow cytometric measurements of the chromosomal DNA content have been used to develop a screening method for the detection of chemically- or physically-induced cytogenetic damage. The reproducibility of this flow cytogenetic assay was shown in a series of subcultures of a Chinese hamster cell clone. The accuracy and sensitivity was tested in cultures treated with chemical mutagens and x-rays. The clastogenic effectiveness was quantified and the dose-effect relationship was established by the increase of the coefficient of variation of the peak of the largest chromosome type in the flow histograms. Since structural chromosome aberrations cause an unequal division of the DNA at mitosis, it is expected that clastogenic effects can be detected also in whole cells of growing populations as an increased dispersion of the cellular DNA content. In order to test this feature, high resolution flow cytometric measurements were performed in x-irradiated hamster cells in vitro and mouse bone marrow cells in vivo.","Flow cytogenetic studies in chromosomes and whole cells for the detection of clastogenic effects Abs: Flow cytometric measurements of the chromosomal DNA content have been used to develop a screening method for the detection of chemically- or physically-induced cytogenetic damage. The reproducibility of this flow cytogenetic assay was shown in a series of subcultures of a Chinese hamster cell clone. The accuracy and sensitivity was tested in cultures treated with chemical mutagens and x-rays. The clastogenic effectiveness was quantified and the dose-effect relationship was established by the increase of the coefficient of variation of the peak of the largest chromosome type in the flow histograms. Since structural chromosome aberrations cause an unequal division of the DNA at mitosis, it is expected that clastogenic effects can be detected also in whole cells of growing populations as an increased dispersion of the cellular DNA content. In order to test this feature, high resolution flow cytometric measurements were performed in x-irradiated hamster cells in vitro and mouse bone marrow cells in vivo."
1238774,Sponza and  Levis 1980,"EFFECTS OF POTASSIUM DICHROMATE, MITOMYCIN C AND METHYL-METHANE-SULFONATE ON THE IN VITRO SYNTHESIS OF POLY DT CATALYZED BY DNA-POLYMERASE ALPHA FROM CALF THYMUS WITH POLY DA.(DT)N",,"EFFECTS OF POTASSIUM DICHROMATE, MITOMYCIN C AND METHYL-METHANE-SULFONATE ON THE IN VITRO SYNTHESIS OF POLY DT CATALYZED BY DNA-POLYMERASE ALPHA FROM CALF THYMUS WITH POLY DA.(DT)N Abs: "
1238773,Majone and  Marin 1980,Single-strand sister chromatid exchanges in chromium-treated Chinese hamster cells,,Single-strand sister chromatid exchanges in chromium-treated Chinese hamster cells Abs: 
1238771,Léonard and  Deknudt 1981,Mutagenicity tests with chromium salts in mouse,,Mutagenicity tests with chromium salts in mouse Abs: 
1238769,Myhr et al. 1981,Blind evaluation of chemicals in the L5178Y/TK+- mouse lympoma forward mutation assay,,Blind evaluation of chemicals in the L5178Y/TK+- mouse lympoma forward mutation assay Abs: 
1238767,Kowbel and  Nestmann 1980,ENHANCED SENSITIVITY OF THE FLUCTUATION ASSAY USING A MODIFIED INCUBATION PROCEDURE,,ENHANCED SENSITIVITY OF THE FLUCTUATION ASSAY USING A MODIFIED INCUBATION PROCEDURE Abs: 
1238764,Dubinin and  Kalinina 1980,TEST SYSTEMS FOR DETECTION OF MUTAGENIC ACTIVITY OF ENVIRONMENTAL POLLUTANTS,,TEST SYSTEMS FOR DETECTION OF MUTAGENIC ACTIVITY OF ENVIRONMENTAL POLLUTANTS Abs: 
1238763,Bianchi et al. 1980,Mechanisms of chromium toxicity in mammalian cell cultures,"Our observations about the cytotoxic and cytogenetic effects of hexavalent and trivalent chromium compounds in mammalian cells cultured in vitro are reviewed. Additional data concerning the induction of chromosomal aberrations and sister chromatid exchanges, the inhibition of nucleic acid and protein synthesis, the interference with nucleotide metabolism, and the modification of membrane-linked enzyme activity are reported. A possible mechanism of chromium action is proposed.","Mechanisms of chromium toxicity in mammalian cell cultures Abs: Our observations about the cytotoxic and cytogenetic effects of hexavalent and trivalent chromium compounds in mammalian cells cultured in vitro are reviewed. Additional data concerning the induction of chromosomal aberrations and sister chromatid exchanges, the inhibition of nucleic acid and protein synthesis, the interference with nucleotide metabolism, and the modification of membrane-linked enzyme activity are reported. A possible mechanism of chromium action is proposed."
1238761,Kowbel and  Nestmann 1981,ENHANCED SENSITIVITY OF THE FLUCTUATION ASSAY USING A MODIFIED INCUBATION PROCEDURE,,ENHANCED SENSITIVITY OF THE FLUCTUATION ASSAY USING A MODIFIED INCUBATION PROCEDURE Abs: 
1238756,Schiemann 1912,MUTATIONS IN ASPERGILLUS NIGER VAN TIEGHEM,,MUTATIONS IN ASPERGILLUS NIGER VAN TIEGHEM Abs: 
1238754,Majone and  Marin 1978,Sister chromatid exchanges in chinese hamster cells exposed to chromium compounds,HEEP COPYRIGHT: BIOL ABS. ABSTRACT CHO OVARY CELL CHROMIUM TRI CHLORIDE POTASSIUM DI CHROMATE MUTAGEN BROMODEOXY URIDINE,Sister chromatid exchanges in chinese hamster cells exposed to chromium compounds Abs: HEEP COPYRIGHT: BIOL ABS. ABSTRACT CHO OVARY CELL CHROMIUM TRI CHLORIDE POTASSIUM DI CHROMATE MUTAGEN BROMODEOXY URIDINE
1238753,Rainaldi et al. 1980,Mutagenicity of K2Cr2O7 in Chinese hamster cells in culture,"Hexavalent chromium compounds, which have been assessed as carcinogenic agents have been shown to induce point mutations in bacteria and yeasts. We show that Cr 6+ is also mutagenic in mammalian cells in culture enhancing in a dose-dependent way the frequency of 6-thioguanine-resistant mutants. It also induces an increase in the number of sister-chromatid exchanges (SCE). Ouabain-resistant mutants are not induced: this result suggests that this chromium compound does not induce missense-type mutations in mammalian cells.","Mutagenicity of K2Cr2O7 in Chinese hamster cells in culture Abs: Hexavalent chromium compounds, which have been assessed as carcinogenic agents have been shown to induce point mutations in bacteria and yeasts. We show that Cr 6+ is also mutagenic in mammalian cells in culture enhancing in a dose-dependent way the frequency of 6-thioguanine-resistant mutants. It also induces an increase in the number of sister-chromatid exchanges (SCE). Ouabain-resistant mutants are not induced: this result suggests that this chromium compound does not induce missense-type mutations in mammalian cells."
1238752,Knudsen 1980,"Effects of welding fume particles, hexavalent chromium and cyclophosphamide in the mammalian spot test",,"Effects of welding fume particles, hexavalent chromium and cyclophosphamide in the mammalian spot test Abs: "
1238747,Egilsson et al. 1979,Toxic and mutagenic effects of carcinogens on the mitochondria of Saccharomyces cerevisiae,"Nineteen haploid yeast (Saccharomyces cerevisiae) strains were used to assess the relative growth inhibitory potencies on fermentable vs. non-fermentable media of a collection of carcinogenic and noncarcinogenic chemicals. The majority of carcinogens were distinctly more potent on the non-fermentable (glycerol) medium, where mitochondrial function is required for growth, than on the fermentable medium, where it is not. The anti-mitochondrial selectivity indicated by these growth tests was much slighter for the non-carcinogens. Similarly most carcinogens induced the cytoplasmic petite mutation whereas the non-carcinogens did not. Five carcinogens which were tested impaired the development of cytochromes aa 3 and b in glucose cultures. Six carcinogens, when tested, inhibited growth on three fermentable sugars, the utilisation of which requires mitochondrial function. Out of five carcinogens which were examined, four suppressed the surface-dependent phenomenon of flocculence in a flocculating strain of yeast, at concentrations primarily affecting the mitochondrial system; the fifth had a similar but less pronounced effect.","Toxic and mutagenic effects of carcinogens on the mitochondria of Saccharomyces cerevisiae Abs: Nineteen haploid yeast (Saccharomyces cerevisiae) strains were used to assess the relative growth inhibitory potencies on fermentable vs. non-fermentable media of a collection of carcinogenic and noncarcinogenic chemicals. The majority of carcinogens were distinctly more potent on the non-fermentable (glycerol) medium, where mitochondrial function is required for growth, than on the fermentable medium, where it is not. The anti-mitochondrial selectivity indicated by these growth tests was much slighter for the non-carcinogens. Similarly most carcinogens induced the cytoplasmic petite mutation whereas the non-carcinogens did not. Five carcinogens which were tested impaired the development of cytochromes aa 3 and b in glucose cultures. Six carcinogens, when tested, inhibited growth on three fermentable sugars, the utilisation of which requires mitochondrial function. Out of five carcinogens which were examined, four suppressed the surface-dependent phenomenon of flocculence in a flocculating strain of yeast, at concentrations primarily affecting the mitochondrial system; the fifth had a similar but less pronounced effect."
1238745,Oguni et al. 1978,EFFECTS OF ENVIRONMENTAL TOXICANTS ON ETHYLENE PRODUCTION IN THE INJURED SWEET POTATO ROOTS,,EFFECTS OF ENVIRONMENTAL TOXICANTS ON ETHYLENE PRODUCTION IN THE INJURED SWEET POTATO ROOTS Abs: 
1238744,Venturini and  Monti-Bragadin 1978,IMPROVEMENT IN THE SENSITIVITY OF DNA POLYMERASE I-DEFICIENT ESCHERICHIA COLI FOR DETECTING MUTAGENS AND CARCINOGENS,,IMPROVEMENT IN THE SENSITIVITY OF DNA POLYMERASE I-DEFICIENT ESCHERICHIA COLI FOR DETECTING MUTAGENS AND CARCINOGENS Abs: 
1238732,Nishioka 1978,Supersensitive DNA repair test -- lliquid method -- for mutagen detection,,Supersensitive DNA repair test -- lliquid method -- for mutagen detection Abs: 
1238731,Matsushima et al. 1978,MUTAGENICITY OF AZO-COMPOUNDS: IMPROVED METHOD FOR DETECTING THEIR MUTAGENICITIES BY THE SALMONELLA MUTATION TEST,,MUTAGENICITY OF AZO-COMPOUNDS: IMPROVED METHOD FOR DETECTING THEIR MUTAGENICITIES BY THE SALMONELLA MUTATION TEST Abs: 
1238727,Nishioka 1978,Super-sensitive DNA-repair test-liquid for confirming DNA-damagicity of mutagens,,Super-sensitive DNA-repair test-liquid for confirming DNA-damagicity of mutagens Abs: 
1238723,Tamino 1977,[Interaction of chromium with nucleic acids mammalian cells],,[Interaction of chromium with nucleic acids mammalian cells] Abs: 
1238722,Bianchi et al. 1977,SPECIFIC EFFECTS OF CR6+ ON NUCLEIC ACID SYNTHESIS AND NUCLEOSIDE UPTAKE IN HAMSTER CELLS (BHK LINE),,SPECIFIC EFFECTS OF CR6+ ON NUCLEIC ACID SYNTHESIS AND NUCLEOSIDE UPTAKE IN HAMSTER CELLS (BHK LINE) Abs: 
1238720,Buttignol et al. 1977,Cytotoxic effects of some carcinogenic industrial pigments containing chromium,,Cytotoxic effects of some carcinogenic industrial pigments containing chromium Abs: 
1238711,Nishioka 1976,AN EXAMPLE OF DETECTION OF ENVIRONMENTAL MUTAGENS AND A POLICY. METAL COMPOUNDS,,AN EXAMPLE OF DETECTION OF ENVIRONMENTAL MUTAGENS AND A POLICY. METAL COMPOUNDS Abs: 
1238709,Kaneko 1976,CHROMOSOME DAMAGE IN CULTURED HUMAN LEUKOCYTES INDUCED BY CHROMIUM CHLORIDE AND CHROMIUM TRIOXIDE,,CHROMOSOME DAMAGE IN CULTURED HUMAN LEUKOCYTES INDUCED BY CHROMIUM CHLORIDE AND CHROMIUM TRIOXIDE Abs: 
1238702,Levis et al. 1975,Chromium cytotoxic effects on mammalian cells in vitro,,Chromium cytotoxic effects on mammalian cells in vitro Abs: 
1238700,Nishioka 1974,"MUTAGENESIS OF METALS IN BACTERIA. 2.ARSENIC, CHROMIUM AND MERCURY COMPOUNDS AND TEST TUBE METHOD FOR DETECTION OF CHEMICAL MUTAGENICITY",,"MUTAGENESIS OF METALS IN BACTERIA. 2.ARSENIC, CHROMIUM AND MERCURY COMPOUNDS AND TEST TUBE METHOD FOR DETECTION OF CHEMICAL MUTAGENICITY Abs: "
1238698,Bigaliev et al. 1977,CYTOGENETIC STUDY OF THE IN VIVO MUTAGENIC PROPERTIES OF CHROMIUM COMPOUNDS,,CYTOGENETIC STUDY OF THE IN VIVO MUTAGENIC PROPERTIES OF CHROMIUM COMPOUNDS Abs: 
1238697,Corbett et al. 1970,Determination of the mutagenic activity to bacteriophage T4 of carcinogenic and noncarcinogenic compounds,"Forty-one carcinogens and four noncarcinogens were tested for mutagenic activity and the kinds of mutational events produced by the active compounds in bacteriophage T4. Twentyfive carcinogens, including many hydrocarbons, were presumed to have no mutagenic activity because they were not toxic to Escherichia coli BB or to T4 phage. Four carcinogenic inorganic salts and five chemical carcinogens (N-hydroxy-1-naphthylamine, N-hydroxy-2-naphthylamine, N-hydroxy-2-aminofluorene, 10-formyl-1,2-benzanthracene, and DL-ethionine) were toxic but not mutagenic to intracellular T4 phage. One compound of definite but low chemical reactivity (the glucuronide of N-hydroxy-2-acetylaminofluorene) was not mutagenic by direct treatment of T4 phage. Six chemically more reactive carcinogens (?-propiolactone, propane sultone, N-acetoxy-2-acetylaminofluorene and its 7-fluoro derivative, glycidaldehyde, and nitrogen mustard) were mutagenic to T4 phage. The types of mutations induced by each compound were determined. The possible relationship between carcinogenesis and mutagenesis is discussed.","Determination of the mutagenic activity to bacteriophage T4 of carcinogenic and noncarcinogenic compounds Abs: Forty-one carcinogens and four noncarcinogens were tested for mutagenic activity and the kinds of mutational events produced by the active compounds in bacteriophage T4. Twentyfive carcinogens, including many hydrocarbons, were presumed to have no mutagenic activity because they were not toxic to Escherichia coli BB or to T4 phage. Four carcinogenic inorganic salts and five chemical carcinogens (N-hydroxy-1-naphthylamine, N-hydroxy-2-naphthylamine, N-hydroxy-2-aminofluorene, 10-formyl-1,2-benzanthracene, and DL-ethionine) were toxic but not mutagenic to intracellular T4 phage. One compound of definite but low chemical reactivity (the glucuronide of N-hydroxy-2-acetylaminofluorene) was not mutagenic by direct treatment of T4 phage. Six chemically more reactive carcinogens (?-propiolactone, propane sultone, N-acetoxy-2-acetylaminofluorene and its 7-fluoro derivative, glycidaldehyde, and nitrogen mustard) were mutagenic to T4 phage. The types of mutations induced by each compound were determined. The possible relationship between carcinogenesis and mutagenesis is discussed."
1238695,Biswas 1985,TOXICITY OF CHROMIUM TO CHICK EMBRYOS: DETERMINATION OF LETHAL DOSE AND DISTRIBUTION OF CHROMIUM IN THE CHICK EMBRYO,,TOXICITY OF CHROMIUM TO CHICK EMBRYOS: DETERMINATION OF LETHAL DOSE AND DISTRIBUTION OF CHROMIUM IN THE CHICK EMBRYO Abs: 
1238694,Ungváry et al. 1989,Pathomechanism of the embryotoxic effect of chromium exposure,"Authors have proved in earlier studies on mice, rats and rabbits, that hexavalent chromium (Cr) is teratogenic and interferes with implantation. In the present study the pathomechanism of interfering with implantation and teratogenic effects of Cr salts were analyzed. It was found that intraamnially administered Cr induces malformation on the 9-12 days of organogenesis, while on the 15th day of gestation it causes the dose-dependent body mass retardation and/or death of embryos. Per os given potassium bichromate increases dose-dependently the maternal blood Cr level following 6-10 hours of administration; 24 hours later the blood Cr level is still significant. Chromium reaches dose-dependent and significant concentration also in the foetal blood and amniotic fluid. Potassium bichromate decreases the level of 17-beta-oestradiol (E2) and progesterone (P) on the peripheral blood. Potassium bichromate decreases the nutritive uterinal blood flow in non-pregnant animals. The authors conclude that chromium cumulates, crosses the placenta, appears in foetal blood and amniotic fluid. Its teratogenic effect is mainly caused by direct cytotoxicity, however, changes of the ratio of the peripheral blood levels of sexual steroids may also play a role. The interference of Cr salts with implantation can readily be explained by their uterinal nutritive blood flow decreasing effect.","Pathomechanism of the embryotoxic effect of chromium exposure Abs: Authors have proved in earlier studies on mice, rats and rabbits, that hexavalent chromium (Cr) is teratogenic and interferes with implantation. In the present study the pathomechanism of interfering with implantation and teratogenic effects of Cr salts were analyzed. It was found that intraamnially administered Cr induces malformation on the 9-12 days of organogenesis, while on the 15th day of gestation it causes the dose-dependent body mass retardation and/or death of embryos. Per os given potassium bichromate increases dose-dependently the maternal blood Cr level following 6-10 hours of administration; 24 hours later the blood Cr level is still significant. Chromium reaches dose-dependent and significant concentration also in the foetal blood and amniotic fluid. Potassium bichromate decreases the level of 17-beta-oestradiol (E2) and progesterone (P) on the peripheral blood. Potassium bichromate decreases the nutritive uterinal blood flow in non-pregnant animals. The authors conclude that chromium cumulates, crosses the placenta, appears in foetal blood and amniotic fluid. Its teratogenic effect is mainly caused by direct cytotoxicity, however, changes of the ratio of the peripheral blood levels of sexual steroids may also play a role. The interference of Cr salts with implantation can readily be explained by their uterinal nutritive blood flow decreasing effect."
1238690,Biswas and  Sanjeevi 1984,TOXICITY OF CHROMIUM TO CHICK EMBRYOS: AN EVALUATION OF ALTERATION IN RATE OF GROWTH THROUGH COMPUTER AIDED REGRESSION ANALYSIS,,TOXICITY OF CHROMIUM TO CHICK EMBRYOS: AN EVALUATION OF ALTERATION IN RATE OF GROWTH THROUGH COMPUTER AIDED REGRESSION ANALYSIS Abs: 
1238689,Lamvermeyer and  Brill 1982,"MURINE AND AVIAN STUDIES OF THE TERATOGENIC AND FETOTOXIC EFFECTS OF ASPIRIN, TETRACYLCINE, HYDROCORTISONE, AND CHROMIUM TRIOXIDE",,"MURINE AND AVIAN STUDIES OF THE TERATOGENIC AND FETOTOXIC EFFECTS OF ASPIRIN, TETRACYLCINE, HYDROCORTISONE, AND CHROMIUM TRIOXIDE Abs: "
1238688,Bookhout et al. 1984,"EFFECTS OF HEXAVALENT CHROMIUM ON DEVELOPMENT OF CRABS, RHITHROPANOPEUS HARRISII AND CALLINECTES SAPIDUS",,"EFFECTS OF HEXAVALENT CHROMIUM ON DEVELOPMENT OF CRABS, RHITHROPANOPEUS HARRISII AND CALLINECTES SAPIDUS Abs: "
1238686,Mearns et al. 1976,CHROMIUM EFFECTS ON COASTAL ORGANISMS,,CHROMIUM EFFECTS ON COASTAL ORGANISMS Abs: 
1238685,Jacquet 1984,THE USE OF THE EMBRYO-CULTURE TECHNIQUES IN THE RESEARCH ON THE TERATOGENIC AND MUTAGENIC PROPERTIES OF METALS,,THE USE OF THE EMBRYO-CULTURE TECHNIQUES IN THE RESEARCH ON THE TERATOGENIC AND MUTAGENIC PROPERTIES OF METALS Abs: 
1238682,Chiang and  Huang 1979,EFFECTS OF HEAVY METALS ON EMBRYO DEVELOPMENT OF THE GRASS CARP (CTENOPHARYNGODON IDELLUS) AND SILVER CARP (HYPOPHTHALMICHTHYS MOLITRIX),,EFFECTS OF HEAVY METALS ON EMBRYO DEVELOPMENT OF THE GRASS CARP (CTENOPHARYNGODON IDELLUS) AND SILVER CARP (HYPOPHTHALMICHTHYS MOLITRIX) Abs: 
1238680,Toi 1979,INHIBITION OF THE GROWTH OF FRESHWATER FISH BY WATER POLLUTANTS. CHEMICAL EFFECTS ON THE DEVELOPMENT OF CARP EGGS,,INHIBITION OF THE GROWTH OF FRESHWATER FISH BY WATER POLLUTANTS. CHEMICAL EFFECTS ON THE DEVELOPMENT OF CARP EGGS Abs: 
1238675,Jacquet and  Draye 1982,TOXICITY OF CHROMIUM SALTS TO CULTURED MOUSE EMBRYOS,,TOXICITY OF CHROMIUM SALTS TO CULTURED MOUSE EMBRYOS Abs: 
1238660,Vogel et al. 1999,The results of assays in Drosophila as indicators of exposure to carcinogens,"Drosophila has fulfilled a dual function in the field of genetic toxicology: for use in short-term tests for identifying carcinogens and in a model for studies of the mechanisms of mutagenesis by chemicals. Until the mid-1980s, use of Drosophila in short-term tests was restricted to assays for genetic damage in germ cells, mostly in males. The largest database, on 700-750 chemicals, is available for the test for sex-linked recessive lethal (SLRL) forward mutation. The database for assays of the consequences of chromosomal breakage--reciprocal translocations and chromosome loss--is smaller, with about 100 chemicals tested. Comparative studies conducted within the US National Toxicology Program showed that SLRL is a better end-point than reciprocal translocation: of 66 chemicals (68 entries) that induced SLRL, only 28 (41%) induced reciprocal translocation. The major weakness of the SLRL assay is its low sensitivity (0.27-0.79) for mammalian genotoxins. A strength of the SLRL mutation test is its high specificity, which is close to 1. Thus, whereas a negative response in Drosophila provides little evidence for genotoxicity, a positive response (SLRL frequency or = five times the control level) provides good evidence that a chemical is a trans-species mutagen and probably also carcinogenic to mammals. The poor performance of the SLRL test revealed in several collaborative studies led to the development of assays for recombination in somatic cells of Drosophila. Two of these tests have been evaluated for all known classes of genotoxic chemical: the mwh/flr wing spot test on more than 400 chemicals and the white/white+ eye spot test on about 220 chemicals. Of 24 carcinogens that gave negative or inconclusive test results in the SLRL assay, 22 gave positive results in one or both of the somatic systems. Their better performance in comparison with the germ-line assays is primarily the result of their low cost (5-10% of that needed for an SLRL assay), allowing use of multiple doses and protocols and the use of distinct tester strains with heterogeneity for activation of procarcinogens. For qualitative and quantitative studies on structure-activity and activity-activity relationship, only germ-line system have been used. In general, clear relationships between physico-chemical parameters (s values, O6/N7-alkylguanine ratios), carcinogenic potency in rodents and several descriptors of genotoxic activity in germ cells (from mice and Drosophila) became apparent when the following descriptors were used: (1) estimates of TD50 (lifetime doses expressed in milligrams per kilogram body weight or millimoles per kilogram body weight) from bioassays for cancer in rodents; (2) the degree of germ-cell specificity, i.e. the ability of a genotoxic agent to induce mutations at practically any stage of development of Drosophila and mouse spermatogenesis, as opposed to a more specific response in postmeiotic stages of both species; (3) the M(NER-)/M(NER+) hypermutability ratio, determined in a repair assay in Drosophila germ cells; (4) the ratio of chromosomal aberrations to SLRL in postmeiotic germ cells of Drosophila, i.e. the comparative efficiency of a carcinogen to induce these two end-points; (5) mutational spectra induced at single loci, i.e. the seven loci used in the specific-locus test in mice and the vermilion, white and rosy genes of Drosophila; and (6) the doubling doses in milligrams or millimoles per kilogram for specific locus induction in mice. On the basis of these parameters, alkylating agents were classified into three categories in terms of germ-cell specificity, which is primarily due to stage-related differences in DNA repair, clastogenic efficiency, type of mutation spectra and carcinogenic potency in rodents. The three categories allow predictions of the genotoxicity of alkylating agents but not yet for other categories of genotoxic carcinogens.","The results of assays in Drosophila as indicators of exposure to carcinogens Abs: Drosophila has fulfilled a dual function in the field of genetic toxicology: for use in short-term tests for identifying carcinogens and in a model for studies of the mechanisms of mutagenesis by chemicals. Until the mid-1980s, use of Drosophila in short-term tests was restricted to assays for genetic damage in germ cells, mostly in males. The largest database, on 700-750 chemicals, is available for the test for sex-linked recessive lethal (SLRL) forward mutation. The database for assays of the consequences of chromosomal breakage--reciprocal translocations and chromosome loss--is smaller, with about 100 chemicals tested. Comparative studies conducted within the US National Toxicology Program showed that SLRL is a better end-point than reciprocal translocation: of 66 chemicals (68 entries) that induced SLRL, only 28 (41%) induced reciprocal translocation. The major weakness of the SLRL assay is its low sensitivity (0.27-0.79) for mammalian genotoxins. A strength of the SLRL mutation test is its high specificity, which is close to 1. Thus, whereas a negative response in Drosophila provides little evidence for genotoxicity, a positive response (SLRL frequency or = five times the control level) provides good evidence that a chemical is a trans-species mutagen and probably also carcinogenic to mammals. The poor performance of the SLRL test revealed in several collaborative studies led to the development of assays for recombination in somatic cells of Drosophila. Two of these tests have been evaluated for all known classes of genotoxic chemical: the mwh/flr wing spot test on more than 400 chemicals and the white/white+ eye spot test on about 220 chemicals. Of 24 carcinogens that gave negative or inconclusive test results in the SLRL assay, 22 gave positive results in one or both of the somatic systems. Their better performance in comparison with the germ-line assays is primarily the result of their low cost (5-10% of that needed for an SLRL assay), allowing use of multiple doses and protocols and the use of distinct tester strains with heterogeneity for activation of procarcinogens. For qualitative and quantitative studies on structure-activity and activity-activity relationship, only germ-line system have been used. In general, clear relationships between physico-chemical parameters (s values, O6/N7-alkylguanine ratios), carcinogenic potency in rodents and several descriptors of genotoxic activity in germ cells (from mice and Drosophila) became apparent when the following descriptors were used: (1) estimates of TD50 (lifetime doses expressed in milligrams per kilogram body weight or millimoles per kilogram body weight) from bioassays for cancer in rodents; (2) the degree of germ-cell specificity, i.e. the ability of a genotoxic agent to induce mutations at practically any stage of development of Drosophila and mouse spermatogenesis, as opposed to a more specific response in postmeiotic stages of both species; (3) the M(NER-)/M(NER+) hypermutability ratio, determined in a repair assay in Drosophila germ cells; (4) the ratio of chromosomal aberrations to SLRL in postmeiotic germ cells of Drosophila, i.e. the comparative efficiency of a carcinogen to induce these two end-points; (5) mutational spectra induced at single loci, i.e. the seven loci used in the specific-locus test in mice and the vermilion, white and rosy genes of Drosophila; and (6) the doubling doses in milligrams or millimoles per kilogram for specific locus induction in mice. On the basis of these parameters, alkylating agents were classified into three categories in terms of germ-cell specificity, which is primarily due to stage-related differences in DNA repair, clastogenic efficiency, type of mutation spectra and carcinogenic potency in rodents. The three categories allow predictions of the genotoxicity of alkylating agents but not yet for other categories of genotoxic carcinogens."
1238659,Mcgregor and  Anderson 1998,DNA damage and repair in mammalian cells in vitro and in vivo as indicators of exposure to carcinogens,,DNA damage and repair in mammalian cells in vitro and in vivo as indicators of exposure to carcinogens Abs: 
1238658,Liu et al. 1999,Mutational specificity in a shuttle vector replicating in chromium(VI)-treated mammalian cells,"An SV40-based shuttle vector, pZ189, was used to characterize the mutation specificity and to explore the mechanism of chromium mutagenesis in mammalian cells. We showed previously that mutagenic DNA damage is induced by the treatment of plasmid with chromium(VI) plus glutathione in vitro. The induced mutation pattern suggested that chromium mutagenesis can be induced by the generation of reactive oxygen intermediates. To further investigate the mechanism of chromium mutagenesis, we treated cultured mammalian cells containing normal pZ189 vector with chromium(VI). Mutations were induced by Cr(VI) in a dose-dependent manner. The majority of base substitution mutations were widely distributed across the supF mutation target gene and occurred mainly at GC basepairs. Overall, the mutation spectra were not significantly different from each other except for a mutation hot spot at position 43, observed only in plasmids from Cr(VI)-treated cells. The characteristics of Cr(VI)-induced mutations were similar to those observed in the mutation spectra induced by H2O2 treatment of the pZ189 plasmid or plasmid-containing cells. These results are consistent with the hypothesis that induction of mutations by chromium in cultured cells occurs through the generation of oxidative DNA damage.","Mutational specificity in a shuttle vector replicating in chromium(VI)-treated mammalian cells Abs: An SV40-based shuttle vector, pZ189, was used to characterize the mutation specificity and to explore the mechanism of chromium mutagenesis in mammalian cells. We showed previously that mutagenic DNA damage is induced by the treatment of plasmid with chromium(VI) plus glutathione in vitro. The induced mutation pattern suggested that chromium mutagenesis can be induced by the generation of reactive oxygen intermediates. To further investigate the mechanism of chromium mutagenesis, we treated cultured mammalian cells containing normal pZ189 vector with chromium(VI). Mutations were induced by Cr(VI) in a dose-dependent manner. The majority of base substitution mutations were widely distributed across the supF mutation target gene and occurred mainly at GC basepairs. Overall, the mutation spectra were not significantly different from each other except for a mutation hot spot at position 43, observed only in plasmids from Cr(VI)-treated cells. The characteristics of Cr(VI)-induced mutations were similar to those observed in the mutation spectra induced by H2O2 treatment of the pZ189 plasmid or plasmid-containing cells. These results are consistent with the hypothesis that induction of mutations by chromium in cultured cells occurs through the generation of oxidative DNA damage."
1238654,Rodriguez and  Akman 1998,Mapping oxidative DNA damage at nucleotide level,"DNA damage induced by reactive oxygen species (ROS) is considered an important intermediate in the pathogenesis of human conditions such as cancer and aging. By developing an oxidative-induced DNA damage mapping version of the Ligation-mediated polymerase chain reaction (LMPCR) technique, we investigated the il vivo and in vitro frequencies of DNA base modifications caused by ROS in the human p53 and PGK1 gene. Intact human male fibroblasts were exposed to 50mM H2O2, or purified genomic DNA was treated with 5 mM H2O2, 100 microM Ascorbate, and 50 microM, 100 microM, or 100 microM of Cu(II), Fe(II), or Cr(VI) respectively. The damage pattern generated in vivo was nearly identical to the in vitro Cu(II) or Fe(III) damage patterns; damage was non-random with guanine bases heavily damaged. Cr(VI) generated an in vitro damage pattern similar to the other metal ions, although several unique thymine positions were damaged. Also, extra nuclear sites are a major contributor of metal ions (or metal-like ligands). These data show that the local probability of H2O2-mediated DNA damage is determined by the primary DNA sequence, with chromatin structure having a limited effect. The data suggest a model in which DNA-metal ion binding domains can accommodate different metalions. LMPCR's unique aspect is a blunt-end ligation of an asymmetric double-stranded linker, permitting exponential PCR amplification. An important factor limiting the sensitivity of LMPCR is the representation of target gene DNA relative to non-targeted genes; therefore, we recently developed a method to eliminate excess non-targeted genomic DNA. Restriction enzyme-digested genomic DNA is size fractionated by Continuous Elution Electrophoresis (CEE), capturing the target sequence of interest. The amount of target DNA in the starting material for LMPCR is enriched, resulting in a stronger amplification signal. CEE provided a 24-fold increase in the signal strength attributable to strand breaks plus modified bases created by ROS in the human p53 and PGK1 genes, detected by LMPCR. We are currently taking advantage of the enhanced sensitivity of target gene-enriched LMPCR to map DNA damage induced in human breast epithelial cells exposed to non-cytotoxic concentrations of H2O2.","Mapping oxidative DNA damage at nucleotide level Abs: DNA damage induced by reactive oxygen species (ROS) is considered an important intermediate in the pathogenesis of human conditions such as cancer and aging. By developing an oxidative-induced DNA damage mapping version of the Ligation-mediated polymerase chain reaction (LMPCR) technique, we investigated the il vivo and in vitro frequencies of DNA base modifications caused by ROS in the human p53 and PGK1 gene. Intact human male fibroblasts were exposed to 50mM H2O2, or purified genomic DNA was treated with 5 mM H2O2, 100 microM Ascorbate, and 50 microM, 100 microM, or 100 microM of Cu(II), Fe(II), or Cr(VI) respectively. The damage pattern generated in vivo was nearly identical to the in vitro Cu(II) or Fe(III) damage patterns; damage was non-random with guanine bases heavily damaged. Cr(VI) generated an in vitro damage pattern similar to the other metal ions, although several unique thymine positions were damaged. Also, extra nuclear sites are a major contributor of metal ions (or metal-like ligands). These data show that the local probability of H2O2-mediated DNA damage is determined by the primary DNA sequence, with chromatin structure having a limited effect. The data suggest a model in which DNA-metal ion binding domains can accommodate different metalions. LMPCR's unique aspect is a blunt-end ligation of an asymmetric double-stranded linker, permitting exponential PCR amplification. An important factor limiting the sensitivity of LMPCR is the representation of target gene DNA relative to non-targeted genes; therefore, we recently developed a method to eliminate excess non-targeted genomic DNA. Restriction enzyme-digested genomic DNA is size fractionated by Continuous Elution Electrophoresis (CEE), capturing the target sequence of interest. The amount of target DNA in the starting material for LMPCR is enriched, resulting in a stronger amplification signal. CEE provided a 24-fold increase in the signal strength attributable to strand breaks plus modified bases created by ROS in the human p53 and PGK1 genes, detected by LMPCR. We are currently taking advantage of the enhanced sensitivity of target gene-enriched LMPCR to map DNA damage induced in human breast epithelial cells exposed to non-cytotoxic concentrations of H2O2."
1238650,Lloyd et al. 1998,Comparison of the formation of 8-hydroxy-2'-deoxyguanosine and single- and double-strand breaks in DNA mediated by fenton reactions,"The formation of 8-hydroxydeoxyguanosine (8-OHdG) and both single- and double-strand breaks in DNA by Fenton-type reactions has been investigated. Salmon sperm DNA was exposed to hydrogen peroxide (50 mM) and one of nine different transition-metal ions (25 microM-1 mM). Modified DNA was isolated and subjected to analysis by liquid chromatography coupled to an electrochemical detection system (LC-ECD), to evaluate the formation of 8-OHdG. The highest yield of 8-OHdG was obtained following treatment of DNA with the chromium(III) Fenton reaction (a maximum of 19 400/10(6) nucleotides), followed by iron(II) (13 600), vanadium(III) (5800), and copper(II) (5200). The chromium(VI) Fenton reaction generated a moderate yield of 8-OHdG (3600/10(6) nucleotides), while the yield obtained in DNA treated with cobalt(II), nickel(II), cadmium(II), and zinc Fenton reactions was not significantly higher than in control incubations of DNA with hydrogen peroxide alone. Similar treatment of the double-stranded plasmid pBluescript K+ with hydrogen peroxide (1 mM) and each transition-metal ion (1-100 microM) followed by quantitative agarose gel electrophoresis demonstrated that open-circle DNA, resulting from single-strand breaks, was generated in Fenton reactions involving all nine metal ions. In contrast, linear DNA was only formed in Fenton reactions involving chromium(III), copper(II), iron(II), and vanadium(III) ions. Formation of linear DNA, under conditions that generated relatively few single-strand breaks, suggests that these four transition-metal ions partake in Fenton reactions to generate true double-strand breaks. Furthermore, the generation of 8-OHdG exhibits a good correlation with the formation of double-strand breaks, suggesting that they arise by a similar mechanism.","Comparison of the formation of 8-hydroxy-2'-deoxyguanosine and single- and double-strand breaks in DNA mediated by fenton reactions Abs: The formation of 8-hydroxydeoxyguanosine (8-OHdG) and both single- and double-strand breaks in DNA by Fenton-type reactions has been investigated. Salmon sperm DNA was exposed to hydrogen peroxide (50 mM) and one of nine different transition-metal ions (25 microM-1 mM). Modified DNA was isolated and subjected to analysis by liquid chromatography coupled to an electrochemical detection system (LC-ECD), to evaluate the formation of 8-OHdG. The highest yield of 8-OHdG was obtained following treatment of DNA with the chromium(III) Fenton reaction (a maximum of 19 400/10(6) nucleotides), followed by iron(II) (13 600), vanadium(III) (5800), and copper(II) (5200). The chromium(VI) Fenton reaction generated a moderate yield of 8-OHdG (3600/10(6) nucleotides), while the yield obtained in DNA treated with cobalt(II), nickel(II), cadmium(II), and zinc Fenton reactions was not significantly higher than in control incubations of DNA with hydrogen peroxide alone. Similar treatment of the double-stranded plasmid pBluescript K+ with hydrogen peroxide (1 mM) and each transition-metal ion (1-100 microM) followed by quantitative agarose gel electrophoresis demonstrated that open-circle DNA, resulting from single-strand breaks, was generated in Fenton reactions involving all nine metal ions. In contrast, linear DNA was only formed in Fenton reactions involving chromium(III), copper(II), iron(II), and vanadium(III) ions. Formation of linear DNA, under conditions that generated relatively few single-strand breaks, suggests that these four transition-metal ions partake in Fenton reactions to generate true double-strand breaks. Furthermore, the generation of 8-OHdG exhibits a good correlation with the formation of double-strand breaks, suggesting that they arise by a similar mechanism."
1238644,Ji et al. 1997,DNA demethylation and pericentromeric rearrangements of chromosome 1,"Rearrangements in the vicinity of the centromere of chromosome 1 are over-represented in many types of human cancer and are a characteristic feature of a rare genetic disease called ICF (immunodeficiency, centromeric heterochromatin instability, and facial anomalies). Evidence is presented that implicates DNA hypomethylation in the formation of these pericentromeric chromosomal anomalies. The DNA methylation inhibitors 5-azadeoxycytidine and 5-azacytidine, but not other tested genotoxins, induced the preferential formation of pericentromeric rearrangements of chromosome 1 at a very high frequency in a pro-B-cell line (FLEB14) and at a lower frequency in a mature B-cell line (AHH-1). These abnormal chromosomes appear identical to the diagnostic chromosomal aberrations in the ICF syndrome. A major component of the pericentromeric DNA in chromosome 1, satellite 2, was shown to be hypomethylated in an ICF B-cell line, although DNA from this cell line did not display detectable overall hypomethylation. It is hypothesized that demethylation in certain DNA regions, including in pericentromeric satellite DNA, helps lead to pericentromeric chromosomal rearrangements in lymphocytes from ICF patients and in normal lymphoblastoid cells incubated in vitro with DNA demethylating agents.","DNA demethylation and pericentromeric rearrangements of chromosome 1 Abs: Rearrangements in the vicinity of the centromere of chromosome 1 are over-represented in many types of human cancer and are a characteristic feature of a rare genetic disease called ICF (immunodeficiency, centromeric heterochromatin instability, and facial anomalies). Evidence is presented that implicates DNA hypomethylation in the formation of these pericentromeric chromosomal anomalies. The DNA methylation inhibitors 5-azadeoxycytidine and 5-azacytidine, but not other tested genotoxins, induced the preferential formation of pericentromeric rearrangements of chromosome 1 at a very high frequency in a pro-B-cell line (FLEB14) and at a lower frequency in a mature B-cell line (AHH-1). These abnormal chromosomes appear identical to the diagnostic chromosomal aberrations in the ICF syndrome. A major component of the pericentromeric DNA in chromosome 1, satellite 2, was shown to be hypomethylated in an ICF B-cell line, although DNA from this cell line did not display detectable overall hypomethylation. It is hypothesized that demethylation in certain DNA regions, including in pericentromeric satellite DNA, helps lead to pericentromeric chromosomal rearrangements in lymphocytes from ICF patients and in normal lymphoblastoid cells incubated in vitro with DNA demethylating agents."
1238633,Van der Lelie et al. 1997,"The VITOTOX test, an SOS bioluminescence Salmonella typhimurium test to measure genotoxicity kinetics","A new test to detect genotoxicity, that we refer to as the VITOTOX test, was developed. Four gene fusions that are based on the Escherichia coli recN promoter were constructed and evaluated for their SOS response-dependent induction. The wild-type recN promoter, a derivative mutated in the second LexA binding site, a derivative with a mutated -35 region, and a derivative from which both the second LexA binding site and the -35 region were mutated, were cloned upstream of the promoterless Vibrio fischeri luxCDABE operon of pMOL877, in such a way that lux became under transcriptional control of the recN promoter derivatives. The inducibility by the SOS response of the promoter constructs was tested in both E. coli and in the Ames test Salmonella typhimurium strains TA98, TA100 and TA104. In all strains, the highest sensitivity and induction was observed with the plasmids pMOL1067 and pMOL1068, that contain the lux operon under control of the recN promoter mutated in the second LexA binding site, or a recN promoter with a mutated -35 region, respectively. Therefore, strains containing pMOL1067 or pMOL1068 were further used for genotoxicity testing. With the VITOTOX test, genotoxicity was detected within 1-4 h. The VITOTOX test is very sensitive: for most products tested, the minimal detectable concentration (MDC) values were considerably lower (5 to 100 times) than those described for the Ames test and the SOS chromotest. A good correlation was observed with the results from the Ames tests, but certain PAHs that are not mutagenic in the Ames test were genotoxic in the VITOTOX test. With the VITOTOX strains, the kinetics of SOS induction can be determined. This feature made it possible to distinguish between compounds in mixtures of genotoxic products so long as they had different induction kinetics.","The VITOTOX test, an SOS bioluminescence Salmonella typhimurium test to measure genotoxicity kinetics Abs: A new test to detect genotoxicity, that we refer to as the VITOTOX test, was developed. Four gene fusions that are based on the Escherichia coli recN promoter were constructed and evaluated for their SOS response-dependent induction. The wild-type recN promoter, a derivative mutated in the second LexA binding site, a derivative with a mutated -35 region, and a derivative from which both the second LexA binding site and the -35 region were mutated, were cloned upstream of the promoterless Vibrio fischeri luxCDABE operon of pMOL877, in such a way that lux became under transcriptional control of the recN promoter derivatives. The inducibility by the SOS response of the promoter constructs was tested in both E. coli and in the Ames test Salmonella typhimurium strains TA98, TA100 and TA104. In all strains, the highest sensitivity and induction was observed with the plasmids pMOL1067 and pMOL1068, that contain the lux operon under control of the recN promoter mutated in the second LexA binding site, or a recN promoter with a mutated -35 region, respectively. Therefore, strains containing pMOL1067 or pMOL1068 were further used for genotoxicity testing. With the VITOTOX test, genotoxicity was detected within 1-4 h. The VITOTOX test is very sensitive: for most products tested, the minimal detectable concentration (MDC) values were considerably lower (5 to 100 times) than those described for the Ames test and the SOS chromotest. A good correlation was observed with the results from the Ames tests, but certain PAHs that are not mutagenic in the Ames test were genotoxic in the VITOTOX test. With the VITOTOX strains, the kinetics of SOS induction can be determined. This feature made it possible to distinguish between compounds in mixtures of genotoxic products so long as they had different induction kinetics."
1238631,Wang et al. 1997,High mobility group proteins 1 and 2 recognize chromium-damaged DNA,"Chromium (Cr) is a human carcinogen and a potent DNA damaging agent. Incubation of DNA with CrCl3 resulted in dose-dependent binding of Cr to DNA and, at concentrations 20 microM, altered the electrophoretic mobility of a 100 bp oligonucleotide. We also demonstrate that high mobility group (HMG) proteins 1 and 2 bind Cr-damaged DNA (Cr-DNA). Protein binding was lesion density-dependent, with maximal binding to DNA treated with 100 microM CrCl3. HMG2 binds to Cr-DNA with a calculated Kd of approximately 10(-9) M. These proteins also bound DNA obtained from chromate-treated cells. These results suggest that the covalent attachment of Cr to DNA induces alterations in DNA structure which are recognized by HMG1 and HMG2. Therefore, these proteins may function as Cr-damaged DNA recognition proteins in vivo and as a consequence of binding, may play a role in directing the cellular response to Cr-DNA adduct formation.","High mobility group proteins 1 and 2 recognize chromium-damaged DNA Abs: Chromium (Cr) is a human carcinogen and a potent DNA damaging agent. Incubation of DNA with CrCl3 resulted in dose-dependent binding of Cr to DNA and, at concentrations 20 microM, altered the electrophoretic mobility of a 100 bp oligonucleotide. We also demonstrate that high mobility group (HMG) proteins 1 and 2 bind Cr-damaged DNA (Cr-DNA). Protein binding was lesion density-dependent, with maximal binding to DNA treated with 100 microM CrCl3. HMG2 binds to Cr-DNA with a calculated Kd of approximately 10(-9) M. These proteins also bound DNA obtained from chromate-treated cells. These results suggest that the covalent attachment of Cr to DNA induces alterations in DNA structure which are recognized by HMG1 and HMG2. Therefore, these proteins may function as Cr-damaged DNA recognition proteins in vivo and as a consequence of binding, may play a role in directing the cellular response to Cr-DNA adduct formation."
1238627,Godet et al. 1996,The genotoxicity of iron and chromium in electroplating effluents,"Electroplating effluents were tested for their genotoxicity with the micronucleus test on newt larvae. The metallic content of the tested samples was responsible for the induction of micronuclei in red blood cells (RBC). Then, iron (Fe3+), chromium (Cr3+, Cr6+) and zinc (Zn2+) which were identified in these samples, were tested either separately or combined, at their concentrations in the electroplating effluents. Fe3+ induced a high level of micronuclei at 12.5 and 25 mg/l (nominal concentrations). Both soluble and non-soluble forms of iron were responsible for these genotoxic effects. At lower concentrations (0.6 and 4.5 mg/l) Fe3+ was not systematically genotoxic. Zinc could not be considered genotoxic on newt. Cr3+ gave negative responses, but exposure to Cr6+ (1 mg/l) could result in a significant number of micronucleated RBC in some cases. The most dramatic genotoxic effects were registered when Fe3+ and Cr6+ were combined. This study demonstrates that interactions between pollutants and the effects of non-soluble chemicals on aquatic vertebrates and invertebrates can no longer be neglected.","The genotoxicity of iron and chromium in electroplating effluents Abs: Electroplating effluents were tested for their genotoxicity with the micronucleus test on newt larvae. The metallic content of the tested samples was responsible for the induction of micronuclei in red blood cells (RBC). Then, iron (Fe3+), chromium (Cr3+, Cr6+) and zinc (Zn2+) which were identified in these samples, were tested either separately or combined, at their concentrations in the electroplating effluents. Fe3+ induced a high level of micronuclei at 12.5 and 25 mg/l (nominal concentrations). Both soluble and non-soluble forms of iron were responsible for these genotoxic effects. At lower concentrations (0.6 and 4.5 mg/l) Fe3+ was not systematically genotoxic. Zinc could not be considered genotoxic on newt. Cr3+ gave negative responses, but exposure to Cr6+ (1 mg/l) could result in a significant number of micronucleated RBC in some cases. The most dramatic genotoxic effects were registered when Fe3+ and Cr6+ were combined. This study demonstrates that interactions between pollutants and the effects of non-soluble chemicals on aquatic vertebrates and invertebrates can no longer be neglected."
1238620,Blaise and  Legault 1994,Comparative assessment of the SOS chromotest kit and the mutatox test with the Salmonella plate incorporation (Ames test) and fluctuation tests for screening genotoxic agents,,Comparative assessment of the SOS chromotest kit and the mutatox test with the Salmonella plate incorporation (Ames test) and fluctuation tests for screening genotoxic agents Abs: 
1238615,Zhitkovich et al. 1996,Formation of the amino acid-DNA complexes by hexavalent and trivalent chromium in vitro: importance of trivalent chromium and the phosphate group,,Formation of the amino acid-DNA complexes by hexavalent and trivalent chromium in vitro: importance of trivalent chromium and the phosphate group Abs: 
1238609,Katsifis et al. 1996,Interaction of nickel with mutagens in the induction of sister chromatid exchanges in human lymphocytes,"In this study, individual treatments of human lymphocytes with Ni(II) [0.5-25 microM], Cr(VI) [0.65-1.30 microM], UV-light or X-rays induced SCEs in a dose-dependent fashion, and combined treatments of Ni(II) with Cr(VI), UV-light or X-rays interacted antagonistically. Nickel, at environmentally relevant exposure levels, can have the effect in complex mixtures of reducing an otherwise positive SCE response and could lead to underestimating human exposures to certain classes of chemicals or radiation. Furthermore, our data indicate that antagonism may occur when human lymphocytes are exposed simultaneously to Ni(II) and Cr(VI), suggesting an explanation for epidemiological studies reporting conflicting results for cytogenetic effects in lymphocytes of workers exposed to chromium and nickel.","Interaction of nickel with mutagens in the induction of sister chromatid exchanges in human lymphocytes Abs: In this study, individual treatments of human lymphocytes with Ni(II) [0.5-25 microM], Cr(VI) [0.65-1.30 microM], UV-light or X-rays induced SCEs in a dose-dependent fashion, and combined treatments of Ni(II) with Cr(VI), UV-light or X-rays interacted antagonistically. Nickel, at environmentally relevant exposure levels, can have the effect in complex mixtures of reducing an otherwise positive SCE response and could lead to underestimating human exposures to certain classes of chemicals or radiation. Furthermore, our data indicate that antagonism may occur when human lymphocytes are exposed simultaneously to Ni(II) and Cr(VI), suggesting an explanation for epidemiological studies reporting conflicting results for cytogenetic effects in lymphocytes of workers exposed to chromium and nickel."
1238608,Stearns et al. 1994,Chromium carcinogenecity: the role of chromium(V) intermediates in chromium(VI)-induced DNA damage,,Chromium carcinogenecity: the role of chromium(V) intermediates in chromium(VI)-induced DNA damage Abs: 
1238586,Costa et al. 1993,Preliminary report on a simple new assay for DNA-protein cross-links as a biomarker of exposures experienced by welders,"A method originally developed to detect topoisomerase DNA complexes has been adapted to determine DNA-protein cross-links formed in cells following their exposure in vitro and in vivo to cross-linking agents. A preliminary study on welders and controls has been carried out to assess the feasibility of this assay to detect human exposure to chromium (Cr) and nickel (Ni) that are associated with increased DNA-protein cross-links. The percentage of cross-link was significantly higher among welders (1.85% +/- 1.14) than among controls (1.17% +/- 0.46; p = .01) Cross-links were not affected by age, weight, or smoking status. The assay developed has substantial advantages over previous methods, being considerably more simple, inexpensive, and sensitive.","Preliminary report on a simple new assay for DNA-protein cross-links as a biomarker of exposures experienced by welders Abs: A method originally developed to detect topoisomerase DNA complexes has been adapted to determine DNA-protein cross-links formed in cells following their exposure in vitro and in vivo to cross-linking agents. A preliminary study on welders and controls has been carried out to assess the feasibility of this assay to detect human exposure to chromium (Cr) and nickel (Ni) that are associated with increased DNA-protein cross-links. The percentage of cross-link was significantly higher among welders (1.85% +/- 1.14) than among controls (1.17% +/- 0.46; p = .01) Cross-links were not affected by age, weight, or smoking status. The assay developed has substantial advantages over previous methods, being considerably more simple, inexpensive, and sensitive."
1238585,Klein et al. 1994,Transgenic gpt+ V79 cell lines differ in their mutagenic response to clastogens,"Several gpt+ transgenic cell lines were derived from hprt V79 cells to study mutagenesis mechanisms in mammalian cells. The G12 cell line was previously shown to be hypermutable by X-rays and UV at the gpt locus compared to the endogenous hprt gene of the parental V79 cells (Klein and Rossman, 1990), and is now shown to be highly mutable by the clastogenic anti-tumor agent bleomycin sulfate. A second transgenic cell line G10, which has a different gpt insertion site, was studied in comparison with G12. Both G12 and G10 cell lines carry the stable gpt locus at a single integration site in the Chinese hamster genome, and neither spontaneously deletes the integrated gpt sequence at a high frequency. Although spontaneous mutation to 6-thioguanine resistance in G10 cells is 3-4 times higher than in G12 cells, the cell lines differ to a much greater extent when mutated by clastogens. In comparison to G12 cells, the gpt locus in G10 cells is up to 13 times more sensitive to bleomycin mutagenesis and 5 times more responsive to X-ray mutagenesis. In contrast, there is much less difference in UV-induced mutagenesis and no differences in mutagenesis induced by alkylating agents such as N-methyl-N'-nitro-N-nitrosoguanidine (MNNG). The dose-dependent decrease in survival of the transgenic cells is the same for all mutagens tested, and does not differ from that of V79 cells. Neither transgenic cell line is generally hypermutable, since mutagenesis at an endogenous gene, Na+K+/ATPase, is similar to that of the parental V79 cell line. Although both cell lines can be induced to delete the transgene following clastogen exposure, deletions are not the only recovered mutations, and the cell lines can also be used to study mutations within the PCR recoverable gpt gene. The utility of these transgenic cells to investigate genome position effects related to mammalian mutagenesis mechanisms is discussed.","Transgenic gpt+ V79 cell lines differ in their mutagenic response to clastogens Abs: Several gpt+ transgenic cell lines were derived from hprt V79 cells to study mutagenesis mechanisms in mammalian cells. The G12 cell line was previously shown to be hypermutable by X-rays and UV at the gpt locus compared to the endogenous hprt gene of the parental V79 cells (Klein and Rossman, 1990), and is now shown to be highly mutable by the clastogenic anti-tumor agent bleomycin sulfate. A second transgenic cell line G10, which has a different gpt insertion site, was studied in comparison with G12. Both G12 and G10 cell lines carry the stable gpt locus at a single integration site in the Chinese hamster genome, and neither spontaneously deletes the integrated gpt sequence at a high frequency. Although spontaneous mutation to 6-thioguanine resistance in G10 cells is 3-4 times higher than in G12 cells, the cell lines differ to a much greater extent when mutated by clastogens. In comparison to G12 cells, the gpt locus in G10 cells is up to 13 times more sensitive to bleomycin mutagenesis and 5 times more responsive to X-ray mutagenesis. In contrast, there is much less difference in UV-induced mutagenesis and no differences in mutagenesis induced by alkylating agents such as N-methyl-N'-nitro-N-nitrosoguanidine (MNNG). The dose-dependent decrease in survival of the transgenic cells is the same for all mutagens tested, and does not differ from that of V79 cells. Neither transgenic cell line is generally hypermutable, since mutagenesis at an endogenous gene, Na+K+/ATPase, is similar to that of the parental V79 cell line. Although both cell lines can be induced to delete the transgene following clastogen exposure, deletions are not the only recovered mutations, and the cell lines can also be used to study mutations within the PCR recoverable gpt gene. The utility of these transgenic cells to investigate genome position effects related to mammalian mutagenesis mechanisms is discussed."
1238574,Olvera et al. 1993,The protective effects of chlorophyllin in treatment with chromium(VI) oxide in somatic cells of Drosophila,,The protective effects of chlorophyllin in treatment with chromium(VI) oxide in somatic cells of Drosophila Abs: 
1238570,Yang et al. 1992,Mutational specificity of chromium(VI) compounds in the hprt locus of Chinese hamster ovary-K1 cells,"Chromium(VI) compounds exert their genotoxicity and mutagenicity by complex metabolic reducing pathways that generate a variety of reactive forms of chromium and free radicals. To investigate the molecular nature of chromium-induced mutations, we characterized the entire coding region of the hypoxanthine (guanine) phosphoribosyltransferase (hprt) gene of 27 independent mutants derived from chromium(VI) oxide (CrO3)-treated Chinese hamster ovary-K1 cells, by direct sequencing of PCR-amplified cDNA. Among these mutants, 10 consisted of single base substitutions, five contained two base substitutions, one had four base substitutions, six were splicing mutations, and five exhibited single base pair insertions or deletions. All of the base substitutions and most of the frameshift mutations observed were located at A/T-rich sequences. More than 90% of the base substitutions (22/24) occurred in A.T base pairs. Among them, T-- A and T-- G transversions (18/22) predominated. The mutational hotspots for single and double base substitutions were the 3' thymidine of 5'PuT and thymidines of 5'ATTT sequences respectively. This mutational specificity was also observed in CHO-K1 cells treated with two other chromium(VI) compounds, namely K2Cr2O7 and PbCrO4. Strand bias was noticed in chromium mutagenicity, since 77% of T base substitutions occurred on the non-transcribed strand. This highly sequence-specific mutation spectrum suggests that a particular form of chromium may directly interact with DNA at these hotspot sequences.","Mutational specificity of chromium(VI) compounds in the hprt locus of Chinese hamster ovary-K1 cells Abs: Chromium(VI) compounds exert their genotoxicity and mutagenicity by complex metabolic reducing pathways that generate a variety of reactive forms of chromium and free radicals. To investigate the molecular nature of chromium-induced mutations, we characterized the entire coding region of the hypoxanthine (guanine) phosphoribosyltransferase (hprt) gene of 27 independent mutants derived from chromium(VI) oxide (CrO3)-treated Chinese hamster ovary-K1 cells, by direct sequencing of PCR-amplified cDNA. Among these mutants, 10 consisted of single base substitutions, five contained two base substitutions, one had four base substitutions, six were splicing mutations, and five exhibited single base pair insertions or deletions. All of the base substitutions and most of the frameshift mutations observed were located at A/T-rich sequences. More than 90% of the base substitutions (22/24) occurred in A.T base pairs. Among them, T-- A and T-- G transversions (18/22) predominated. The mutational hotspots for single and double base substitutions were the 3' thymidine of 5'PuT and thymidines of 5'ATTT sequences respectively. This mutational specificity was also observed in CHO-K1 cells treated with two other chromium(VI) compounds, namely K2Cr2O7 and PbCrO4. Strand bias was noticed in chromium mutagenicity, since 77% of T base substitutions occurred on the non-transcribed strand. This highly sequence-specific mutation spectrum suggests that a particular form of chromium may directly interact with DNA at these hotspot sequences."
1238558,De Flora et al. 1987,DT DIAPHORASE AND THE ACTION OF CHEMICAL MUTAGENS AND CARCINOGENS,"THE EFFECTS OF DICUMAROL, A SPECIFIC INHIBITOR OF DT-DIAPHORASE, WERE INVESTIGATED IN THE AMES REVERSION TEST BY ASSAYING SEVERAL MUTAGENS OF DIFFERENT CHEMICAL CLASSES IN THE PRESENCE OF A VARIETY OF METABOLIC SYSTEMS. DICUMAROL PARTIALLY PREVENTED THE METABOLIC LOSS OF MUTAGENICITY OF FIVE HEXAVALENT CHROMIUM COMPOUNDS AND, VERY EFFICIENTLY, INHIBITED THE METABOLISM OF 4-NITROQUINOLINE-N-OXIDE. THESE FINDINGS RAISE THE HYPOTHESIS THAT DT-DIAPHORASE (A) MAY PLAY SOME ROLE ALSO IN THE METABOLISM OF INORGANIC COMPOUNDS AND (B) MAY BE INVOLVED NOT ONLY IN THE DETOXIFICATION BUT ALSO IN THE METABOLIC ACTIVATION OF CARCINOGENS.","DT DIAPHORASE AND THE ACTION OF CHEMICAL MUTAGENS AND CARCINOGENS Abs: THE EFFECTS OF DICUMAROL, A SPECIFIC INHIBITOR OF DT-DIAPHORASE, WERE INVESTIGATED IN THE AMES REVERSION TEST BY ASSAYING SEVERAL MUTAGENS OF DIFFERENT CHEMICAL CLASSES IN THE PRESENCE OF A VARIETY OF METABOLIC SYSTEMS. DICUMAROL PARTIALLY PREVENTED THE METABOLIC LOSS OF MUTAGENICITY OF FIVE HEXAVALENT CHROMIUM COMPOUNDS AND, VERY EFFICIENTLY, INHIBITED THE METABOLISM OF 4-NITROQUINOLINE-N-OXIDE. THESE FINDINGS RAISE THE HYPOTHESIS THAT DT-DIAPHORASE (A) MAY PLAY SOME ROLE ALSO IN THE METABOLISM OF INORGANIC COMPOUNDS AND (B) MAY BE INVOLVED NOT ONLY IN THE DETOXIFICATION BUT ALSO IN THE METABOLIC ACTIVATION OF CARCINOGENS."
1238557,Olvera et al. 1992,PROTECTIVE EFFECT OF CHLOROPHYLLIN AGAINST CHROMIUM VI IN DROSOPHILA,"CHLOROPHYLLIN, THE SODIUM AND COPPER SALT OF CHLOROPHYLL, WAS TESTED FOR ITS ABILITY TO INHIBIT THE MUTAGENIC ACTIVITY OF CHROMIUM TRIOXIDE ON DROSOPHILA MELANOGASTER USING THE WING-SPOT TEST DESCRIBED BY GRAF ET AL. (1984). FEMALES OF THE GENOTYPE MWH WERE MATED WITH FLR3/TM3; SER MALES. SECOND INSTAR LARVAE WERE COLLECTED, WASHED AND PLACED IN VIALS CONTAINING INSTANT MEDIUM CONTAINING CRO3 (5 MM) CHLOROPHYLLIN (5%), OR CRO3 + CHLOROPHYLLIN. A NEGATIVE CONTROL WAS INCLUDED. THE LARVAE REMAINED IN THE VIALS UNTIL COMPLETE DEVELOPMENT. WINGS FROM MWH+/+FLR3 (NON-SER) ADULTS WERE MOUNTED ON SLIDES. SCORING WAS CARRIED OUT FOR THE PRESENCE OF SMALL, LARGE AND TWIN SPOTS. CHLOROPHYLLIN AT THIS CONCENTRATION WAS NONTOXIC. GRAF ET AL (IN PRESS) HAVE SHOWN WITH THE WING SPOT TEST THAT THE HIGH GENOTOXIC ACTIVITY OF CHROMIUM (VI) OXIDE IS OVER 90% DUE TO RECOMBINOGENIC ACTIVITY TAKING IN CONSIDERATION THAT CHLOROPHYLLIN CAN INHIBIT THE RECOMBINOGENIC EFFECT OF CRO3. THE RESULTS INDICATE THAT CHLOROPHYLLIN IN COMBINATION WITH CRO3 REDUCED THE FREQUENCY OF SINGLE (3.97-1.23) LARGE (3.6-7.6) AND TWIN SPOTS (2.77-0.81) PER WING.","PROTECTIVE EFFECT OF CHLOROPHYLLIN AGAINST CHROMIUM VI IN DROSOPHILA Abs: CHLOROPHYLLIN, THE SODIUM AND COPPER SALT OF CHLOROPHYLL, WAS TESTED FOR ITS ABILITY TO INHIBIT THE MUTAGENIC ACTIVITY OF CHROMIUM TRIOXIDE ON DROSOPHILA MELANOGASTER USING THE WING-SPOT TEST DESCRIBED BY GRAF ET AL. (1984). FEMALES OF THE GENOTYPE MWH WERE MATED WITH FLR3/TM3; SER MALES. SECOND INSTAR LARVAE WERE COLLECTED, WASHED AND PLACED IN VIALS CONTAINING INSTANT MEDIUM CONTAINING CRO3 (5 MM) CHLOROPHYLLIN (5%), OR CRO3 + CHLOROPHYLLIN. A NEGATIVE CONTROL WAS INCLUDED. THE LARVAE REMAINED IN THE VIALS UNTIL COMPLETE DEVELOPMENT. WINGS FROM MWH+/+FLR3 (NON-SER) ADULTS WERE MOUNTED ON SLIDES. SCORING WAS CARRIED OUT FOR THE PRESENCE OF SMALL, LARGE AND TWIN SPOTS. CHLOROPHYLLIN AT THIS CONCENTRATION WAS NONTOXIC. GRAF ET AL (IN PRESS) HAVE SHOWN WITH THE WING SPOT TEST THAT THE HIGH GENOTOXIC ACTIVITY OF CHROMIUM (VI) OXIDE IS OVER 90% DUE TO RECOMBINOGENIC ACTIVITY TAKING IN CONSIDERATION THAT CHLOROPHYLLIN CAN INHIBIT THE RECOMBINOGENIC EFFECT OF CRO3. THE RESULTS INDICATE THAT CHLOROPHYLLIN IN COMBINATION WITH CRO3 REDUCED THE FREQUENCY OF SINGLE (3.97-1.23) LARGE (3.6-7.6) AND TWIN SPOTS (2.77-0.81) PER WING."
1238556,Klein et al. 1992,Chromium mutagenesis in transgenicGPT+ Chinese hamster cell lines,"Chromium mutagenesis has been studied in two transgenic GPT+/HPRT- V79-derived Chinese hamster cell lines. Both G12 and G10 cells are hypermutable with X-rays and bleomycin at their GPT locus compared to the HPRT locus of wild type V79 cells, but these cell lines are not generally hypermutable with MNNG at either the GPT or endogenous NA+K+/atpase loci. Cell line dependent differences in GPT mutability (G10 G12) are noted with x-rays, bleomycin, UV, and mamsa; however this is not true for MNNG or chromate (0-30 umole k2cro4 or k2cr2o7). Chromate mutagenesis fluctuates from 3 to 10 fold above the spontaneous mutant frequencies. Residual toxicity of cr to G12 and G10 cells up to one week after exposure suggests that reduced chromium may be unable to escape from the cells. This may be one reason why chromate is not a strong mutagen in many systems. We have also noted non-random G12 cell detachment upon rinsing the culture dishes after CR exposure (2h) in mg-freee salts glucose medium (SGM). For mutagenesis assays that require recovery of anchorage dependent cells, this results in higher than expected toxicity estimates and decreased mutant yields. Cr treatment in Earle's Balanced Salt Solution (EBSS) or serum-free F12 reduced detachment and CR toxicity. To minimize cell loss and maximize mutant yield, we now utilize SGM plus mg (SGMM).","Chromium mutagenesis in transgenicGPT+ Chinese hamster cell lines Abs: Chromium mutagenesis has been studied in two transgenic GPT+/HPRT- V79-derived Chinese hamster cell lines. Both G12 and G10 cells are hypermutable with X-rays and bleomycin at their GPT locus compared to the HPRT locus of wild type V79 cells, but these cell lines are not generally hypermutable with MNNG at either the GPT or endogenous NA+K+/atpase loci. Cell line dependent differences in GPT mutability (G10 G12) are noted with x-rays, bleomycin, UV, and mamsa; however this is not true for MNNG or chromate (0-30 umole k2cro4 or k2cr2o7). Chromate mutagenesis fluctuates from 3 to 10 fold above the spontaneous mutant frequencies. Residual toxicity of cr to G12 and G10 cells up to one week after exposure suggests that reduced chromium may be unable to escape from the cells. This may be one reason why chromate is not a strong mutagen in many systems. We have also noted non-random G12 cell detachment upon rinsing the culture dishes after CR exposure (2h) in mg-freee salts glucose medium (SGM). For mutagenesis assays that require recovery of anchorage dependent cells, this results in higher than expected toxicity estimates and decreased mutant yields. Cr treatment in Earle's Balanced Salt Solution (EBSS) or serum-free F12 reduced detachment and CR toxicity. To minimize cell loss and maximize mutant yield, we now utilize SGM plus mg (SGMM)."
1238554,Graf et al. 1992,The genotoxicity of chromium(VI) oxide in the wing spot test of Drosophila melanogaster is over 90% due to mitotic recombination,Chromium(VI) oxide and chromium(III) chloride were tested in the wing somatic mutation and recombination test (SMART) in Drosophila melanogaster according to standard procedures. The hexavalent compound was highly genotoxic in both chronic and acute treatments whereas the trivalent one was clearly negative. Further analysis of wings carrying an inversion chromosome which eliminates all recombination events showed that over 90% of the spots induced by chromium(VI) oxide are due to mitotic recombination.,The genotoxicity of chromium(VI) oxide in the wing spot test of Drosophila melanogaster is over 90% due to mitotic recombination Abs: Chromium(VI) oxide and chromium(III) chloride were tested in the wing somatic mutation and recombination test (SMART) in Drosophila melanogaster according to standard procedures. The hexavalent compound was highly genotoxic in both chronic and acute treatments whereas the trivalent one was clearly negative. Further analysis of wings carrying an inversion chromosome which eliminates all recombination events showed that over 90% of the spots induced by chromium(VI) oxide are due to mitotic recombination.
1238553,Standeven and  Wetterhahn 1991,Is there a role for reactive oxygen species in the mechanism of chromium(VI) carcinogenesis?,,Is there a role for reactive oxygen species in the mechanism of chromium(VI) carcinogenesis? Abs: 
1238550,Sasaki and  Et 1991,MICRONUCLEUS TEST WITH MOUSE PERIPHERAL BLOOD ERYTHROCYTES: SUMMARY REPORT OF THE FIFTH COLLABORATIVE STUDY BY THE COLLABORATIVE STUDY GROUP FOR THE MICRONUCLEUS TEST (CSGMT/JEMS.MMS),"IN GENERAL, THE MICRONUCLEUS TEST IS PERFORMED WITH MOUSE BONE MARROW CELLS. ALTHOUGH MICRONUCLEI ARE KNOWN TO BE DETECTABLE IN PERIPHERAL ERYTHROCYTES (MACGREGOR ET AL., 1980), THE USEFULNESS OF THE MICRONUCLEUS TEST IN MOUSE PERIPHERAL ERYTHROCYTES IS NOT WELL KNOWN. RECENTLY, HAYASHI ET AL. (1990) REPORTED A NEW METHOD FOR THE PREPARATION AND OBSERVATION OF PERIPHERAL BLOOD MICRONUCLEI USING ACRIDINE ORANGE-COATED GLASS SLIDES. THE PURPOSE OF THE FIFTH COLLABORATIVE STUDY BY CSGMT/JEMS.MMS WAS TO VALIDATE THE NEW METHOD FOR THE PERIPHERAL BLOOD MICRONUCLEUS TEST. THE CHEMICALS STUDIED WERE 2-ACETYLAMINOFLUORENE, ARA-C, 5-FU, 6-MP, B(A)P, DMBA, METHOTREXATE, PHENACETIN, CYCLOPHOSPHAMIDE, EMS, MMS, TRIETHYLENEMELAMINE, MNNG, DMN, ENU, MMC, KBRO3, K2CRO4, COLCHICINE, VINCRISTINE, BENZENE, PROCARBAZINE, AND URETHANE. FIVE 8-WEEK-OLD CD-1 MALE MICE PER GROUP WERE INTRAPERITONEALLY OR ORALLY TREATED WITH ONE OF THE MUTAGENS. PERIPHERAL BLOOD FROM THE SAME INDIVIDUAL WAS EXAMINED AT 0, 24, 48 AND 72 H AFTER TREATMENT. THE FREQUENCIES OF MICRONUCLEATED PERIPHERAL RETICULOCYTES WERE RECORDED BASED ON AN OBSERVATION OF 1000 CELLS PER MOUSE. GENERALLY ALL CHEMICALS INDUCED AS MANY MICRONUCLEI IN RETICULOCYTES AS IN BONE MARROW CELLS. MOST CHEMICALS SHOWED THE PEAK RESPONSE 48 H AFTER THE TREATMENT. THE PERIPHERAL RETICULOCTYE MICRONUCLEUS TEST IS THEREFORE A USEFUL ALTERNATIVE WITH ADVANTAGES OVER THE BONE MARROW ASSAY.","MICRONUCLEUS TEST WITH MOUSE PERIPHERAL BLOOD ERYTHROCYTES: SUMMARY REPORT OF THE FIFTH COLLABORATIVE STUDY BY THE COLLABORATIVE STUDY GROUP FOR THE MICRONUCLEUS TEST (CSGMT/JEMS.MMS) Abs: IN GENERAL, THE MICRONUCLEUS TEST IS PERFORMED WITH MOUSE BONE MARROW CELLS. ALTHOUGH MICRONUCLEI ARE KNOWN TO BE DETECTABLE IN PERIPHERAL ERYTHROCYTES (MACGREGOR ET AL., 1980), THE USEFULNESS OF THE MICRONUCLEUS TEST IN MOUSE PERIPHERAL ERYTHROCYTES IS NOT WELL KNOWN. RECENTLY, HAYASHI ET AL. (1990) REPORTED A NEW METHOD FOR THE PREPARATION AND OBSERVATION OF PERIPHERAL BLOOD MICRONUCLEI USING ACRIDINE ORANGE-COATED GLASS SLIDES. THE PURPOSE OF THE FIFTH COLLABORATIVE STUDY BY CSGMT/JEMS.MMS WAS TO VALIDATE THE NEW METHOD FOR THE PERIPHERAL BLOOD MICRONUCLEUS TEST. THE CHEMICALS STUDIED WERE 2-ACETYLAMINOFLUORENE, ARA-C, 5-FU, 6-MP, B(A)P, DMBA, METHOTREXATE, PHENACETIN, CYCLOPHOSPHAMIDE, EMS, MMS, TRIETHYLENEMELAMINE, MNNG, DMN, ENU, MMC, KBRO3, K2CRO4, COLCHICINE, VINCRISTINE, BENZENE, PROCARBAZINE, AND URETHANE. FIVE 8-WEEK-OLD CD-1 MALE MICE PER GROUP WERE INTRAPERITONEALLY OR ORALLY TREATED WITH ONE OF THE MUTAGENS. PERIPHERAL BLOOD FROM THE SAME INDIVIDUAL WAS EXAMINED AT 0, 24, 48 AND 72 H AFTER TREATMENT. THE FREQUENCIES OF MICRONUCLEATED PERIPHERAL RETICULOCYTES WERE RECORDED BASED ON AN OBSERVATION OF 1000 CELLS PER MOUSE. GENERALLY ALL CHEMICALS INDUCED AS MANY MICRONUCLEI IN RETICULOCYTES AS IN BONE MARROW CELLS. MOST CHEMICALS SHOWED THE PEAK RESPONSE 48 H AFTER THE TREATMENT. THE PERIPHERAL RETICULOCTYE MICRONUCLEUS TEST IS THEREFORE A USEFUL ALTERNATIVE WITH ADVANTAGES OVER THE BONE MARROW ASSAY."
1238548,He and  Joseph 2006,Gene Expression Profile In Human Skin Fibroblasts Exposed To Potassium Dichromate,"Chromium containing compounds are extensively used in various applications resulting in significant human exposure. Several adverse health effects, including irritant and allergic contact dermatitis, have been reported among workers following occupational exposure to chromium containing compounds. In order to better understand the molecular mechanisms responsible for the dermal toxicity of chromium, differential gene expression profiles of human skin fibroblasts exposed to a cytotoxic concentration of hexavalent potassium dichromate [Cr(VI)] were studied. Skin fibroblasts were exposed to 5 uM Cr(VI) for time intervals up to 24- hr and their differential gene expression profile was studied using the Toxicology and Drug Resistance Microarray (Super Array Inc.). Of the 280 genes represented on the array, the expression levels of 32 genes were found to be differentially affected in the fibroblasts exposed to Cr(VI). In general, genes involved in stress response, cell cycle control, drug metabolism, apoptosis and growth were differentially expressed in response to Cr(VI) exposure. The role of intracellular glutathione on the Cr(VI)-induced alterations in the expression of genes was further investigated using heme oxygenase 1 (HO-1) as the model gene. Modulating the intracellular glutathione level by pre-treating the cells with either BSO (buthionine- Sulfoximine) or glutathione significantly influenced the potential of Cr(VI) to induce expression of the HO-1 gene. Pre-treating the cells with BSO resulted in a significant reduction in glutathione levels. The Cr-induced overexpression of the HO-1 gene in the BSO-treated cells was significantly higher than in those cells without BSO treatment. On the other hand, pre-treating the cells with glutathione partially blocked the Cr(VI)-induced overexpression of the HO-1 gene. In conclusion, our results demonstrate that Cr(VI) exerts its toxic effects in human skin fibroblasts by multiple mechanisms involved in various cellular functions; and the cellular glutathione level appears to be an important factor influencing Cr(VI)?s effects on the expression of genes.","Gene Expression Profile In Human Skin Fibroblasts Exposed To Potassium Dichromate Abs: Chromium containing compounds are extensively used in various applications resulting in significant human exposure. Several adverse health effects, including irritant and allergic contact dermatitis, have been reported among workers following occupational exposure to chromium containing compounds. In order to better understand the molecular mechanisms responsible for the dermal toxicity of chromium, differential gene expression profiles of human skin fibroblasts exposed to a cytotoxic concentration of hexavalent potassium dichromate [Cr(VI)] were studied. Skin fibroblasts were exposed to 5 uM Cr(VI) for time intervals up to 24- hr and their differential gene expression profile was studied using the Toxicology and Drug Resistance Microarray (Super Array Inc.). Of the 280 genes represented on the array, the expression levels of 32 genes were found to be differentially affected in the fibroblasts exposed to Cr(VI). In general, genes involved in stress response, cell cycle control, drug metabolism, apoptosis and growth were differentially expressed in response to Cr(VI) exposure. The role of intracellular glutathione on the Cr(VI)-induced alterations in the expression of genes was further investigated using heme oxygenase 1 (HO-1) as the model gene. Modulating the intracellular glutathione level by pre-treating the cells with either BSO (buthionine- Sulfoximine) or glutathione significantly influenced the potential of Cr(VI) to induce expression of the HO-1 gene. Pre-treating the cells with BSO resulted in a significant reduction in glutathione levels. The Cr-induced overexpression of the HO-1 gene in the BSO-treated cells was significantly higher than in those cells without BSO treatment. On the other hand, pre-treating the cells with glutathione partially blocked the Cr(VI)-induced overexpression of the HO-1 gene. In conclusion, our results demonstrate that Cr(VI) exerts its toxic effects in human skin fibroblasts by multiple mechanisms involved in various cellular functions; and the cellular glutathione level appears to be an important factor influencing Cr(VI)?s effects on the expression of genes."
1238547,Savery et al. 2006,Particulate chromium induced DNA-DNA crosslinks lead to chromosome damage,"Hexavalent chromium (Cr(VI)) is a known human carcinogen. Cr(VI)-induced tumors exhibit chromosome instability (CIN), however the mechanisms of these effects are unknown. Cr(VI) causes DNA-DNA crosslinks and chromosomal aberrations, but it is unknown if these lesions are related. Thus, we investigated the hypothesis that Cr-induced DNA-DNA crosslinks lead to chromosome damage. To test this, we used cell lines deficient in genes from the fanc pathway believed to be important in crosslink repair. Chinese hamster ovary (CHO) KO40 (FANCG-) and human fibroblast PD20.F (FANCD2-) cells were employed to determine if they were hypersensitive to lead chromate. We found that the relative survival of KO40 cells (FANCG-) treated with lead chromate did not differ from the parental AA8 cells or the FANCG gene restored cells (KO40BP6). Specifically, 5 ug/cm2 lead chromate induced 72, 83 and 81% relative survival for KO40, AA8 and KO40BP6, respectively. Lead chromate did induce higher levels of chromosome damage in KO40 cells compared to AA8 and KO40BP6 cells with 5 ug/cm2 lead chromate inducing 33.5, 19.5 and 16.0 aberrations in 100 metaphases. To ensure the cytotoxicity and genotoxicity data reflected the toxicity of lead chromate and not a difference in metal ion uptake between cell lines, chromium uptake was measured and did not change these results. The relative survival of FANCD2- cells treated with lead chromate also did not differ from FANCD2 gene restored cells with 5 ug/cm2 lead chromate inducing 16 and 9% relative survival, respectively. These data collectively suggest that lead chromate-induced DNA-DNA crosslinks are related to lead chromate-induced chromosome damage, but not to cytotoxicity.","Particulate chromium induced DNA-DNA crosslinks lead to chromosome damage Abs: Hexavalent chromium (Cr(VI)) is a known human carcinogen. Cr(VI)-induced tumors exhibit chromosome instability (CIN), however the mechanisms of these effects are unknown. Cr(VI) causes DNA-DNA crosslinks and chromosomal aberrations, but it is unknown if these lesions are related. Thus, we investigated the hypothesis that Cr-induced DNA-DNA crosslinks lead to chromosome damage. To test this, we used cell lines deficient in genes from the fanc pathway believed to be important in crosslink repair. Chinese hamster ovary (CHO) KO40 (FANCG-) and human fibroblast PD20.F (FANCD2-) cells were employed to determine if they were hypersensitive to lead chromate. We found that the relative survival of KO40 cells (FANCG-) treated with lead chromate did not differ from the parental AA8 cells or the FANCG gene restored cells (KO40BP6). Specifically, 5 ug/cm2 lead chromate induced 72, 83 and 81% relative survival for KO40, AA8 and KO40BP6, respectively. Lead chromate did induce higher levels of chromosome damage in KO40 cells compared to AA8 and KO40BP6 cells with 5 ug/cm2 lead chromate inducing 33.5, 19.5 and 16.0 aberrations in 100 metaphases. To ensure the cytotoxicity and genotoxicity data reflected the toxicity of lead chromate and not a difference in metal ion uptake between cell lines, chromium uptake was measured and did not change these results. The relative survival of FANCD2- cells treated with lead chromate also did not differ from FANCD2 gene restored cells with 5 ug/cm2 lead chromate inducing 16 and 9% relative survival, respectively. These data collectively suggest that lead chromate-induced DNA-DNA crosslinks are related to lead chromate-induced chromosome damage, but not to cytotoxicity."
1238546,Xie et al. 2006,ATM And MRE11 Are Involved In The Repair Of Particulate Chromium (VI) -Induced Dna Double Strand Breaks,"Chromium(VI) (Cr(VI)) is a potent respiratory toxicant and carcinogen with widespread human exposure. The most toxic and carcinogenic forms of Cr(VI) are particulates such as lead chromate (LC), which deposit and persist in the respiratory tract after inhalation. Lead chromate particles are genotoxic to cultured fibroblasts and epithelia. The particle-derived Cr(VI) ion enters the cell where it undergoes a uniquely complex scheme of reductive metabolism, producing a cascade of reactive intermediates which produce numerous types of DNA damage. Our previous study linked lead chromate to DNA double strand breaks (DSBs) formation, one of the most dangerous types of DNA damage. Thus the aim of this study was to understand the mechanisms of repair of lead chromate-induced DNA DSBs. Using the comet assay, we found that LC induced concentration dependent increases in DSBs in normal human lung cells with 0.1, 0.5, 1, and 5 ug/cm2 LC inducing 14, 24, 32 and 37 percent relative increase in tail DNA relative to control, respectively. We found that repair of these lesions occurred within 24 h. In response to DNA damage, cells arrest the cell cycle to facilitate repair or initiate apoptosis. We found that LC caused S-phase arrest and increased levels of phosphorylated SMC1 expression. LC also induced ATM and MRE11 expression in these cells. To begin understanding the mechanism of repair for these lesions, we treated ATM deficient and MRE11 deficient cells with LC. We found that LC induces DSBs in ATM deficient cells and MRE11 deficient cells and the repair of these lesions is greatly decreased. Using an immunofluorescence assay we found that MRE11 and H2A.X foci co-localize after LC exposure. These data indicate that MRE11 and ATM are involved in LC-induced DSBs sensing and repair.","ATM And MRE11 Are Involved In The Repair Of Particulate Chromium (VI) -Induced Dna Double Strand Breaks Abs: Chromium(VI) (Cr(VI)) is a potent respiratory toxicant and carcinogen with widespread human exposure. The most toxic and carcinogenic forms of Cr(VI) are particulates such as lead chromate (LC), which deposit and persist in the respiratory tract after inhalation. Lead chromate particles are genotoxic to cultured fibroblasts and epithelia. The particle-derived Cr(VI) ion enters the cell where it undergoes a uniquely complex scheme of reductive metabolism, producing a cascade of reactive intermediates which produce numerous types of DNA damage. Our previous study linked lead chromate to DNA double strand breaks (DSBs) formation, one of the most dangerous types of DNA damage. Thus the aim of this study was to understand the mechanisms of repair of lead chromate-induced DNA DSBs. Using the comet assay, we found that LC induced concentration dependent increases in DSBs in normal human lung cells with 0.1, 0.5, 1, and 5 ug/cm2 LC inducing 14, 24, 32 and 37 percent relative increase in tail DNA relative to control, respectively. We found that repair of these lesions occurred within 24 h. In response to DNA damage, cells arrest the cell cycle to facilitate repair or initiate apoptosis. We found that LC caused S-phase arrest and increased levels of phosphorylated SMC1 expression. LC also induced ATM and MRE11 expression in these cells. To begin understanding the mechanism of repair for these lesions, we treated ATM deficient and MRE11 deficient cells with LC. We found that LC induces DSBs in ATM deficient cells and MRE11 deficient cells and the repair of these lesions is greatly decreased. Using an immunofluorescence assay we found that MRE11 and H2A.X foci co-localize after LC exposure. These data indicate that MRE11 and ATM are involved in LC-induced DSBs sensing and repair."
1238544,Patlolla and  Tchounwou 2006,In vivo genotoxic effect of hexavalent chromium in rat leukocytes using comet assay,"Chromium exists mostly in two valence states in nature: hexavalent [Cr (VI)] and trivalent [Cr (III)]. Hexavalent chromium is commonly used in industrial chrome plating, welding, painting, metal finishes, steel manufacturing, alloy, cast iron and wood treatment, and is proven toxin, mutagen and carcinogen. The mechanistic cytotoxicity of chromium (VI) is not completely understood. In the present investigation, single-/double stranded DNA breaks by potassium dichromate [K2Cr2O7] in Sprague-Dawley rats, a sensitive model for genotoxic effects, have been studied in vivo using alkaline single-cell gel electrophoresis [SCGE] comet assay. Four groups of 5 male rats each weighing an average of 60 + 2 g were used in this study. Potassium dichromate was intraperitoneally administered to the rats at the doses of 2.5, 5, 7.5 and 10 mg/kg bodyweight (BW), and one dose per 24 hours given for 5 days and samples of whole blood were collected at 24, 48, 72 and 96 h post-treatment for alkaline SCGE assay to study DNA damage. A control group was also made of 5 animals injected with distilled water without chemical. The rationale for using leukocytes was to reflect biomarker analysis in humans. All the doses of potassium dichromate induced significant increase in mean comet tail length [6.23 ? 33.42 uM] indicating DNA damage when compared with controls [2.79 uM]. Maximum increase in mean comet tail length was observed at 10 mg/kg (BW) at 48h post-treatment [33.42 uM]. The mean comet tail length showed a clear dose-dependent increase from 2.5 to 10 mg/kg BW. A gradual decrease in the tail lengths from 72h post-treatment [3.74 uM] was observed by the 96h and values had returned almost to control levels at all doses, indicating repair of the damaged DNA and/or loss of heavily damaged cells. The study indicates that the alkaline comet assay is a reliable, sensitive and rapid method to detect DNA damage caused by heavy metals such as chromium.","In vivo genotoxic effect of hexavalent chromium in rat leukocytes using comet assay Abs: Chromium exists mostly in two valence states in nature: hexavalent [Cr (VI)] and trivalent [Cr (III)]. Hexavalent chromium is commonly used in industrial chrome plating, welding, painting, metal finishes, steel manufacturing, alloy, cast iron and wood treatment, and is proven toxin, mutagen and carcinogen. The mechanistic cytotoxicity of chromium (VI) is not completely understood. In the present investigation, single-/double stranded DNA breaks by potassium dichromate [K2Cr2O7] in Sprague-Dawley rats, a sensitive model for genotoxic effects, have been studied in vivo using alkaline single-cell gel electrophoresis [SCGE] comet assay. Four groups of 5 male rats each weighing an average of 60 + 2 g were used in this study. Potassium dichromate was intraperitoneally administered to the rats at the doses of 2.5, 5, 7.5 and 10 mg/kg bodyweight (BW), and one dose per 24 hours given for 5 days and samples of whole blood were collected at 24, 48, 72 and 96 h post-treatment for alkaline SCGE assay to study DNA damage. A control group was also made of 5 animals injected with distilled water without chemical. The rationale for using leukocytes was to reflect biomarker analysis in humans. All the doses of potassium dichromate induced significant increase in mean comet tail length [6.23 ? 33.42 uM] indicating DNA damage when compared with controls [2.79 uM]. Maximum increase in mean comet tail length was observed at 10 mg/kg (BW) at 48h post-treatment [33.42 uM]. The mean comet tail length showed a clear dose-dependent increase from 2.5 to 10 mg/kg BW. A gradual decrease in the tail lengths from 72h post-treatment [3.74 uM] was observed by the 96h and values had returned almost to control levels at all doses, indicating repair of the damaged DNA and/or loss of heavily damaged cells. The study indicates that the alkaline comet assay is a reliable, sensitive and rapid method to detect DNA damage caused by heavy metals such as chromium."
1238543,Joseph and  Othumpangat 2005,Eukaryotic translation initiation factor 4E is a cellular target for arsenic but not chromium toxicity,"The mRNA cap binding translation factor, eukaryotic translation initiation factor 4E (eIF4E), was studied as a potential cellular target for the toxicity and cell death induced by arsenic and chromium. Human cell lines HCT15, PLC/PR/5, HeLa and Chang, were treated with sodium arsenite (As) and potassium dichromate (Cr). Exposure to both As and Cr resulted in significant cytotoxicity and cell death in all four cell lines. In all the cell lines treated with As and Cr, the transcript for eIF4E did not exhibit any change compared with the corresponding control cells. However, in the cells treated with As alone, the cellular expression level of eIF4E protein was significantly lower compared to the corresponding control cells. Further studies revealed that exposure of cells to As, but not to Cr, resulted in significant induction of ubiquitination of eIF4E protein. Results of the experiments involving inhibitors for the cellular proteasome pathway confirmed that the exposure of As but not Cr activated the proteolysis of eIF4E mediated through the ubiquitin/ proteasome pathway. Whether the As-induced cytotoxicity and cell death were due to the inhibition of eIF4E was studied by specifically silencing the expression of eIF4E gene using a small interfering RNA (SiRNA) targeting eIF4E gene expression. The SiRNA-mediated silencing of eIF4E gene resulted in cytotoxicity and cell death suggesting that eIF4E is a potential cellular target for cytotoxicity and cell death due to exposure to As.","Eukaryotic translation initiation factor 4E is a cellular target for arsenic but not chromium toxicity Abs: The mRNA cap binding translation factor, eukaryotic translation initiation factor 4E (eIF4E), was studied as a potential cellular target for the toxicity and cell death induced by arsenic and chromium. Human cell lines HCT15, PLC/PR/5, HeLa and Chang, were treated with sodium arsenite (As) and potassium dichromate (Cr). Exposure to both As and Cr resulted in significant cytotoxicity and cell death in all four cell lines. In all the cell lines treated with As and Cr, the transcript for eIF4E did not exhibit any change compared with the corresponding control cells. However, in the cells treated with As alone, the cellular expression level of eIF4E protein was significantly lower compared to the corresponding control cells. Further studies revealed that exposure of cells to As, but not to Cr, resulted in significant induction of ubiquitination of eIF4E protein. Results of the experiments involving inhibitors for the cellular proteasome pathway confirmed that the exposure of As but not Cr activated the proteolysis of eIF4E mediated through the ubiquitin/ proteasome pathway. Whether the As-induced cytotoxicity and cell death were due to the inhibition of eIF4E was studied by specifically silencing the expression of eIF4E gene using a small interfering RNA (SiRNA) targeting eIF4E gene expression. The SiRNA-mediated silencing of eIF4E gene resulted in cytotoxicity and cell death suggesting that eIF4E is a potential cellular target for cytotoxicity and cell death due to exposure to As."
1238542,Holmes et al. 2005,Chronic exposure to lead ions from lead chromate interferes with normal mitotic progression,"Hexavalent chromium (Cr(VI)) compounds are established human lung carcinogens. Solubility plays a key role in the carcinogenicity of Cr(VI), with the most potent carcinogens being the particulate Cr(VI) compounds, however, it remains unknown why. Lead chromate(LC) and sodium chromate(SC) were used as model particulate and soluble Cr(VI) compounds, respectively. We tested the hypothesis that the Pb cation may disrupt normal mitotic progression after chronic exposures to LC, by determining the presence of c-anaphase cells after exposure to LC, SC and lead glutamate (LG). LC induced concentration and time-dependent increases in intracellular Cr ions, but only concentration-dependent increases in intracellular Pb ions. LC induced concentration-dependent increases in chromosome damage after a 24 h exposure, but only a small increase in c-anaphase cells. However, more chronic exposures to LC induced a greater increase in c-anaphase cells. Specifically, after exposure to 0.5 ug/cm2 LC for 24, 48 and 72 h, c-anaphase cells increased from 1 to 6 to 16%, respectively, with none in the control. Concentrations of 0.5, 1 and 2.5 uM SC, which have similar intracellular Cr levels as the LC treatments, did not induce c-anaphase cells indicating that the Cr ions are not causing this effect. We next selected soluble Pb ion treatments (50 and 100 uM LG), that mimicked the amount of Pb ions inside the cell after LC exposure and found that Pb ions did induce an increase in c-anaphase cells. Specifically, 50 and 100 uM LG induced a 3.5 and 6.5% increase in c-anaphase cells, respectively. These data indicate that chronic exposure to Pb ions from LC disrupts normal mitotic progression in human lung cells and may be exerting an epigenetic effect as part of the overall carcinogenic mechanism of lead chromate.","Chronic exposure to lead ions from lead chromate interferes with normal mitotic progression Abs: Hexavalent chromium (Cr(VI)) compounds are established human lung carcinogens. Solubility plays a key role in the carcinogenicity of Cr(VI), with the most potent carcinogens being the particulate Cr(VI) compounds, however, it remains unknown why. Lead chromate(LC) and sodium chromate(SC) were used as model particulate and soluble Cr(VI) compounds, respectively. We tested the hypothesis that the Pb cation may disrupt normal mitotic progression after chronic exposures to LC, by determining the presence of c-anaphase cells after exposure to LC, SC and lead glutamate (LG). LC induced concentration and time-dependent increases in intracellular Cr ions, but only concentration-dependent increases in intracellular Pb ions. LC induced concentration-dependent increases in chromosome damage after a 24 h exposure, but only a small increase in c-anaphase cells. However, more chronic exposures to LC induced a greater increase in c-anaphase cells. Specifically, after exposure to 0.5 ug/cm2 LC for 24, 48 and 72 h, c-anaphase cells increased from 1 to 6 to 16%, respectively, with none in the control. Concentrations of 0.5, 1 and 2.5 uM SC, which have similar intracellular Cr levels as the LC treatments, did not induce c-anaphase cells indicating that the Cr ions are not causing this effect. We next selected soluble Pb ion treatments (50 and 100 uM LG), that mimicked the amount of Pb ions inside the cell after LC exposure and found that Pb ions did induce an increase in c-anaphase cells. Specifically, 50 and 100 uM LG induced a 3.5 and 6.5% increase in c-anaphase cells, respectively. These data indicate that chronic exposure to Pb ions from LC disrupts normal mitotic progression in human lung cells and may be exerting an epigenetic effect as part of the overall carcinogenic mechanism of lead chromate."
1238541,Duzevik et al. 2005,Repair of chromate-induced chromosome damage is mediated by XRCC1,"Chromium (VI) compounds are established human carcinogens that induce chromosomal aberrations and DNA damage. The mechanisms by which this damage is repaired is unknown. DNA repair mechanisms include several proteins necessary for the successful repair of DNA damage. XRCC1 is a protein involved in the repair of DNA single strand breaks (SSB). In this study we examined the role of XRCC1 in cell survival and repair of chromosomal aberrations induced by particulate and soluble chromium compounds in Chinese hamster ovary (CHO) cells. Three different cell lines were used: AA8 (parental), EM9 (XRCC1 mutant) and H9T3 (EM9 complemented with human XRCC1 gene). Results show a concentrationdependant decrease in relative survival in all cell lines. Relative survival in AA8 cells treated with 0.1, 0.5, 1.0, 5.0 ?g/cm2 lead chromate (LC) was 103, 98, 98 and 83%, and was 89, 82, 69 and 37% in XRCC1 deficient (EM9) cells, respectively. However, relative survival was not different in EM9 compared to AA8 and H9T3 cells treated with 1.0, 2.5, 5.0 and 10.0 ?M sodium chromate (SC). LC was clastogenic inducing 0.25, 0.78 and 0.52 aberrations/cell at 0.1, 0.5 and 1 ?g/cm2 respectively in AA8 cells. In EM9 cells, 0.1, 0.5 and 1 ?g/cm2 LC caused 0.61, 0.85 and 0.96 aberrations/cell respectively. Recovery experiments show that repair was efficient in the parental cell line and the number of chromosomal aberrations was not increased, while in EM9 cells total damage was dramatically increased, especially at higher concentrations. Results for the H9T3 cells were similar to those for parental cell line. These data indicate that XRCC1 is important for cell survival of particulate chromate treated cells, but not in sodium chromate treated cells. XRCC1 is required for repair of particulate and soluble chromate induced chromosomal aberrations. Future studies will be directed towards further examining the functional role of XRCC1 in repair of chromium(VI)-induced DNA SSB.","Repair of chromate-induced chromosome damage is mediated by XRCC1 Abs: Chromium (VI) compounds are established human carcinogens that induce chromosomal aberrations and DNA damage. The mechanisms by which this damage is repaired is unknown. DNA repair mechanisms include several proteins necessary for the successful repair of DNA damage. XRCC1 is a protein involved in the repair of DNA single strand breaks (SSB). In this study we examined the role of XRCC1 in cell survival and repair of chromosomal aberrations induced by particulate and soluble chromium compounds in Chinese hamster ovary (CHO) cells. Three different cell lines were used: AA8 (parental), EM9 (XRCC1 mutant) and H9T3 (EM9 complemented with human XRCC1 gene). Results show a concentrationdependant decrease in relative survival in all cell lines. Relative survival in AA8 cells treated with 0.1, 0.5, 1.0, 5.0 ?g/cm2 lead chromate (LC) was 103, 98, 98 and 83%, and was 89, 82, 69 and 37% in XRCC1 deficient (EM9) cells, respectively. However, relative survival was not different in EM9 compared to AA8 and H9T3 cells treated with 1.0, 2.5, 5.0 and 10.0 ?M sodium chromate (SC). LC was clastogenic inducing 0.25, 0.78 and 0.52 aberrations/cell at 0.1, 0.5 and 1 ?g/cm2 respectively in AA8 cells. In EM9 cells, 0.1, 0.5 and 1 ?g/cm2 LC caused 0.61, 0.85 and 0.96 aberrations/cell respectively. Recovery experiments show that repair was efficient in the parental cell line and the number of chromosomal aberrations was not increased, while in EM9 cells total damage was dramatically increased, especially at higher concentrations. Results for the H9T3 cells were similar to those for parental cell line. These data indicate that XRCC1 is important for cell survival of particulate chromate treated cells, but not in sodium chromate treated cells. XRCC1 is required for repair of particulate and soluble chromate induced chromosomal aberrations. Future studies will be directed towards further examining the functional role of XRCC1 in repair of chromium(VI)-induced DNA SSB."
1238540,Xie et al. 2005,Carcinogenic Lead Chromate Induces DNA Double-Strand Breaks And Activates ATM Kinase In Human Lung Cells,"Hexavalent chromium (Cr(VI)) is a widespread environmental contaminant and a known human carcinogen, generally causing bronchial cancer. Studies have shown that it is the particulate forms of Cr(VI) that are the potent carcinogens. Particulate Cr(VI) is known to induce a spectrum of DNA damage such as DNA single strand breaks, Cr-DNA adducts, DNA-protein crosslinks and chromosomal aberrations. However, particulate Cr(VI)-induced DNA double strand breaks (DSBs) have not been reported. Thus the aim of this study is to determine if particulate Cr(VI)-induces DSB in human lung cells. Using the single cell gel electrophoresis assay (comet assay), we found that lead chromate (LC) induced concentration dependent increases in DSBs with 0.1, 0.5, 1, 5 and 10 ug/cm2 lead chromate inducing a 0.21, 0.50, 0.62, 1.10 and 1.68-fold relative increase in tail integrated intensity ratio, respectively. To begin to understand the mechanisms in the repair of these lesions, we detected H2A.X foci formation in cells treated with LC. H2A.X becomes rapidly phosphorylated (r-H2A.X) on residue serine 139 and forms foci surrounding damaged DNA in response to DSBs. r-H2A.X foci formation is believed to be a sensitive signal for the existence of DSBs. By using immunofluorescence, we found that lead chromate induced concentration-dependent increases in r-H2A.X foci formation with 0.1, 0.5, 1, 5 and 10 ug/cm2 LC inducing a 1.4, 1.5, 2.1, 2.2, 2.4 fold increase relative to control, respectively . The ataxia telangiectasia mutated (ATM) protein plays a central role in early stages of DSBs detection and controls cellular responses to this damage. We also found that LC activates ATM at concentrations that are both genotoxic and cytotoxic. Future experiments will focus on elucidating the role of ATM and related genes in the mechanism of DSBs repair.","Carcinogenic Lead Chromate Induces DNA Double-Strand Breaks And Activates ATM Kinase In Human Lung Cells Abs: Hexavalent chromium (Cr(VI)) is a widespread environmental contaminant and a known human carcinogen, generally causing bronchial cancer. Studies have shown that it is the particulate forms of Cr(VI) that are the potent carcinogens. Particulate Cr(VI) is known to induce a spectrum of DNA damage such as DNA single strand breaks, Cr-DNA adducts, DNA-protein crosslinks and chromosomal aberrations. However, particulate Cr(VI)-induced DNA double strand breaks (DSBs) have not been reported. Thus the aim of this study is to determine if particulate Cr(VI)-induces DSB in human lung cells. Using the single cell gel electrophoresis assay (comet assay), we found that lead chromate (LC) induced concentration dependent increases in DSBs with 0.1, 0.5, 1, 5 and 10 ug/cm2 lead chromate inducing a 0.21, 0.50, 0.62, 1.10 and 1.68-fold relative increase in tail integrated intensity ratio, respectively. To begin to understand the mechanisms in the repair of these lesions, we detected H2A.X foci formation in cells treated with LC. H2A.X becomes rapidly phosphorylated (r-H2A.X) on residue serine 139 and forms foci surrounding damaged DNA in response to DSBs. r-H2A.X foci formation is believed to be a sensitive signal for the existence of DSBs. By using immunofluorescence, we found that lead chromate induced concentration-dependent increases in r-H2A.X foci formation with 0.1, 0.5, 1, 5 and 10 ug/cm2 LC inducing a 1.4, 1.5, 2.1, 2.2, 2.4 fold increase relative to control, respectively . The ataxia telangiectasia mutated (ATM) protein plays a central role in early stages of DSBs detection and controls cellular responses to this damage. We also found that LC activates ATM at concentrations that are both genotoxic and cytotoxic. Future experiments will focus on elucidating the role of ATM and related genes in the mechanism of DSBs repair."
1238539,Arreola-Mendoza et al. 2005,Protective effect of alpha-tocopherol on renal injury caused by chromate exposure,"Chromate Cr(VI) is a common industrial waste product and environmental pollutant. It is also a recognized human carcinogen. Some toxic effects of Cr(VI) exposure have been related with its oxidative capacity. In the kidney, exposure to Cr(VI) has been associated with proximal tubular necrosis, although its mechanism remains unclear. Our aim was to examine acute renal damage caused by the exposure of Cr(VI), to disclose the degree of lipid peroxidation (LPO) cause by this metal and the functional consequences on different nephron segments (glomeruli, proximal and distal tubules). We also assessed the segmental selectivity of the protective effect of alpha-tocopherol on these alterations. Wistar female rats (200 g bw) received potassium dichromate (15 mg/kg, sc, single dose). LPO and renal function were monitored on days 0, 1, 2, 3, 7, 10 y 14 after Cr(VI) administration. A second group received alpha-tocopherol (125 mg/kg/day, gavage), 5 days before and 7 days after Cr(VI), and were monitored on 0, 2 and 7 days of Cr(VI) exposure. LPO was quantified in renal tissue; creatinine clearance, glucose and sodium fractional excretions, free-water and osmolal clearances were also measured. Results showed oxidative damage 48 h after exposure to Cr(VI) with spontaneous recovery after day 7. Renal function was maximally altered on day 3 and thereafter recovery ensued. Glomerular filtration decreased, glucose and sodium fractional excretions increased and free water and osmolal were affected. These changes showed a similar timecourse to that of the oxidative damage. alpha-tocopherol-treated group showed less oxidative damage and preservation of proximal tubule function. In contrast, glomerular and distal function did not show difference with the group that received Cr(VI) alone. These results suggest that Cr(VI) causes alterations along different segments of the nephron and the antioxidant treatment had protective effect only on the injury caused by Cr(VI) on the proximal tubular function.","Protective effect of alpha-tocopherol on renal injury caused by chromate exposure Abs: Chromate Cr(VI) is a common industrial waste product and environmental pollutant. It is also a recognized human carcinogen. Some toxic effects of Cr(VI) exposure have been related with its oxidative capacity. In the kidney, exposure to Cr(VI) has been associated with proximal tubular necrosis, although its mechanism remains unclear. Our aim was to examine acute renal damage caused by the exposure of Cr(VI), to disclose the degree of lipid peroxidation (LPO) cause by this metal and the functional consequences on different nephron segments (glomeruli, proximal and distal tubules). We also assessed the segmental selectivity of the protective effect of alpha-tocopherol on these alterations. Wistar female rats (200 g bw) received potassium dichromate (15 mg/kg, sc, single dose). LPO and renal function were monitored on days 0, 1, 2, 3, 7, 10 y 14 after Cr(VI) administration. A second group received alpha-tocopherol (125 mg/kg/day, gavage), 5 days before and 7 days after Cr(VI), and were monitored on 0, 2 and 7 days of Cr(VI) exposure. LPO was quantified in renal tissue; creatinine clearance, glucose and sodium fractional excretions, free-water and osmolal clearances were also measured. Results showed oxidative damage 48 h after exposure to Cr(VI) with spontaneous recovery after day 7. Renal function was maximally altered on day 3 and thereafter recovery ensued. Glomerular filtration decreased, glucose and sodium fractional excretions increased and free water and osmolal were affected. These changes showed a similar timecourse to that of the oxidative damage. alpha-tocopherol-treated group showed less oxidative damage and preservation of proximal tubule function. In contrast, glomerular and distal function did not show difference with the group that received Cr(VI) alone. These results suggest that Cr(VI) causes alterations along different segments of the nephron and the antioxidant treatment had protective effect only on the injury caused by Cr(VI) on the proximal tubular function."
1238538,Chen and  Chakrabarti 2005,Studies of mechanisms of potassium dichromate-induced nephrotoxicity in isolated rat renal cortical slices,"The kidney is considered to be one of the target organs for Cr(VI) toxicity. The information regarding the mechanisms of Cr(VI)-induced nephrotoxicity is at present very limited. The present study was carried out to investigate the mechanisms of Cr6+(using potassium dichromate)-induced toxicity in isolated rat renal cortical slices. The dichromate (Cr6+) showed both concentration (0-4 mM) and time (0-3 hr) dependent toxicity, as measured by the MTT assay. The dichromate (1 mM) produced both time-dependent significant depletion of nonprotein sulfhydryl contents and significant increase in lipid peroxidation (LPO), which appeared much later than the former. Pretreatment of cortical slices with either mannitol or dimethylthiourea failed to reduce Cr6+-induced toxicity but reduced LPO. Similarly, pretreatment with either catalase or superoxide dismutase failed to reduce such toxicity. However, treatment with either excess glutathione (GSH) or pretreatment with excess ascorbic acid (Vit.C) reduced both the toxicity and LPO. Although Cr6+ induced mitochondrial permeability transition (MPT), cyclosporin A, or carnitine, or trifluoperazine (inhibitors of MPT) failed to prevent such toxicity, suggesting a non-significant role of MPT in such toxicity. Cotreatment with some modulators of intracellular calcium fluxes failed to prevent such toxicity indicating a nonsignificant role of calcium homeostasis. Pretreatment with carmustine failed to prevent Cr6+-induced toxicity suggesting a nonsignificant role of glutathione reductase activity in such toxicity. The results suggest that depletion of GSH might be a determinant step in the oxidative stress and subsequent nephrotoxicity and that Vit.C is a powerful antioxidant to prevent such toxicity.","Studies of mechanisms of potassium dichromate-induced nephrotoxicity in isolated rat renal cortical slices Abs: The kidney is considered to be one of the target organs for Cr(VI) toxicity. The information regarding the mechanisms of Cr(VI)-induced nephrotoxicity is at present very limited. The present study was carried out to investigate the mechanisms of Cr6+(using potassium dichromate)-induced toxicity in isolated rat renal cortical slices. The dichromate (Cr6+) showed both concentration (0-4 mM) and time (0-3 hr) dependent toxicity, as measured by the MTT assay. The dichromate (1 mM) produced both time-dependent significant depletion of nonprotein sulfhydryl contents and significant increase in lipid peroxidation (LPO), which appeared much later than the former. Pretreatment of cortical slices with either mannitol or dimethylthiourea failed to reduce Cr6+-induced toxicity but reduced LPO. Similarly, pretreatment with either catalase or superoxide dismutase failed to reduce such toxicity. However, treatment with either excess glutathione (GSH) or pretreatment with excess ascorbic acid (Vit.C) reduced both the toxicity and LPO. Although Cr6+ induced mitochondrial permeability transition (MPT), cyclosporin A, or carnitine, or trifluoperazine (inhibitors of MPT) failed to prevent such toxicity, suggesting a non-significant role of MPT in such toxicity. Cotreatment with some modulators of intracellular calcium fluxes failed to prevent such toxicity indicating a nonsignificant role of calcium homeostasis. Pretreatment with carmustine failed to prevent Cr6+-induced toxicity suggesting a nonsignificant role of glutathione reductase activity in such toxicity. The results suggest that depletion of GSH might be a determinant step in the oxidative stress and subsequent nephrotoxicity and that Vit.C is a powerful antioxidant to prevent such toxicity."
1238537,Beger et al. 2005,Pattern recognition of NMR spectra of urine from Wistar rats dosed with liver and renal toxicants,"A collaboration between Pfizer and the Center of Metabolomics Research at NCTR was initiated to study the ability of NMR in combination with pattern recognition techniques to rapidly detect toxicity in urine samples. Single doses of 4-aminophenol (150 mg/kg), puromycin aminonucleoside (150 mg/kg), Sodium Chromate (25 mg/kg), hexachlorobutadiene (200 mg/kg), Galactosamine (600 mg/kg), Allyl Alcohol (120 mg/kg), and thioacetamide (200 mg/kg) were administered to 4 adult male Wistar rats. Urine samples were collected daily in metabolism cages at Pfizer and monitored by 1D 1H NMR at NCTR. The NMR spectra of urine were binned using ACD?s ?intelligent binning? for statistical analysis. Two-dimensional principal component analysis (PCA) of the binned NMR spectra from urine on the second day after dosing was able to clearly differentiate rats dosed with renal toxins from rats dosed with hepatoxins. Partial least squares-discriminant function (PLSDF) models built from NMR spectra from day 2 urine samples were able to differentiate between renal toxicity, hepatotoxicity, and control samples.","Pattern recognition of NMR spectra of urine from Wistar rats dosed with liver and renal toxicants Abs: A collaboration between Pfizer and the Center of Metabolomics Research at NCTR was initiated to study the ability of NMR in combination with pattern recognition techniques to rapidly detect toxicity in urine samples. Single doses of 4-aminophenol (150 mg/kg), puromycin aminonucleoside (150 mg/kg), Sodium Chromate (25 mg/kg), hexachlorobutadiene (200 mg/kg), Galactosamine (600 mg/kg), Allyl Alcohol (120 mg/kg), and thioacetamide (200 mg/kg) were administered to 4 adult male Wistar rats. Urine samples were collected daily in metabolism cages at Pfizer and monitored by 1D 1H NMR at NCTR. The NMR spectra of urine were binned using ACD?s ?intelligent binning? for statistical analysis. Two-dimensional principal component analysis (PCA) of the binned NMR spectra from urine on the second day after dosing was able to clearly differentiate rats dosed with renal toxins from rats dosed with hepatoxins. Partial least squares-discriminant function (PLSDF) models built from NMR spectra from day 2 urine samples were able to differentiate between renal toxicity, hepatotoxicity, and control samples."
1238536,Wise et al. 2005,Genotoxicity Of Particulate Uranium And Chromium,"Depleted uranium (DU) and hexavalent chromate (Cr(VI)) are commonly used by the military and thus exposure of soldiers and non-combatants to these compounds is potentially frequent and widespread. Particulate forms of these metals are a concern because of their ability to impact and persist at bifurcation sites in the lung. Cr(VI) is a known human lung carcinogen and DU is considered a probable human carcinogen, affecting the bronchial cells of the lung. However, the mechanisms of Cr(VI)-induced carcinogenesis are unknown and only one investigation has studied particulate DU and only two have studied soluble DU in human bronchial cells. Thus the primary goal of this study was to characterize and compare the genotoxicity of Cr(VI) and DU in human bronchial cells. We found that lead chromate, was less toxic to human lung cells than similar concentrations of uranium oxide. Specifically, at concentrations of 0.5, 1, 5 and 10 ug/cm2, lead chromate induced 71, 43, 15, and 1 percent survival (relative to the control), respectively, while uranium oxide induced 57, 32, 1 and 0 percent survival respectively at these same concentrations. By contrast, we found that lead chromate was more clastogenic than uranium oxide in human lung cells. Uranium oxide induced 6, 9, 15 and 26 percent damage at concentrations of 0.5, 1, 5 and 10 ug/cm2 while lead chromate induced 27 and 37 percent damage at the lower concentrations of 0.5 and 1 ug/cm2. At 5 and 10 ug/cm2, lead chromate induced cell cycle arrest and no metaphases were observed. Future work will consider potential effects of co-exposure to these cells and their ability to induce neoplastic transformation.","Genotoxicity Of Particulate Uranium And Chromium Abs: Depleted uranium (DU) and hexavalent chromate (Cr(VI)) are commonly used by the military and thus exposure of soldiers and non-combatants to these compounds is potentially frequent and widespread. Particulate forms of these metals are a concern because of their ability to impact and persist at bifurcation sites in the lung. Cr(VI) is a known human lung carcinogen and DU is considered a probable human carcinogen, affecting the bronchial cells of the lung. However, the mechanisms of Cr(VI)-induced carcinogenesis are unknown and only one investigation has studied particulate DU and only two have studied soluble DU in human bronchial cells. Thus the primary goal of this study was to characterize and compare the genotoxicity of Cr(VI) and DU in human bronchial cells. We found that lead chromate, was less toxic to human lung cells than similar concentrations of uranium oxide. Specifically, at concentrations of 0.5, 1, 5 and 10 ug/cm2, lead chromate induced 71, 43, 15, and 1 percent survival (relative to the control), respectively, while uranium oxide induced 57, 32, 1 and 0 percent survival respectively at these same concentrations. By contrast, we found that lead chromate was more clastogenic than uranium oxide in human lung cells. Uranium oxide induced 6, 9, 15 and 26 percent damage at concentrations of 0.5, 1, 5 and 10 ug/cm2 while lead chromate induced 27 and 37 percent damage at the lower concentrations of 0.5 and 1 ug/cm2. At 5 and 10 ug/cm2, lead chromate induced cell cycle arrest and no metaphases were observed. Future work will consider potential effects of co-exposure to these cells and their ability to induce neoplastic transformation."
1238535,Kolacinski et al. 2004,Toxicokinetics of Chromium Elimination in Hemodialysis and Forced Diuresis Based on a Case of Potassium Dichromate Intoxication,"Objective: In the toxicological literature there is no one defined and commonly accepted standard concerning chromium intoxication treatment. The question of administrating elimination procedures (hemodialysis, forced diuresis) in such cases is especially controversial. The aim of this report is a comparative study of the effectiveness of hemodialysis and forced diuresis as the methods of treatment in acute potassium dichromate poisoning. Case Report: A 54-years-old patient accidentally drank an aqueous solution of wood preservative. The main ingredient of the solution was potassium dichromate. It was impossible to specify neither the exact volume of the drunken liquid or the concentration of the active agent. The patient drank water and provoked vomiting immediately after the intake of the solution. Patient?s general state on admission (4 hours after the intoxication) was quite good. He complained of abdominal pain, nausea and a burning sensation localised along the oesophagus. The patient was vomiting gastric contents with a considerable amount of blood. Urine output was appropriate, lab tests were normal, not suggestive of renal failure. An 8-hour hemodialysis together with forced diuresis were initiated approximately one hour after admission. Cuprofan dialysator of the surface of 1.6 m2 was used, blood flow (Qb) was 200 mL/min, dialysate flow (Qd) 616 mL/min. Renal clearance for chromium and dialysance were checked every 2 hours during the dialysis. Chromium levels in plasma, urine and dialysate samples were determined by graphite furnace atomic absorption spectrophotometry using Perkin Elmer model 4100 ZL Zeeman with an autosampler AS-70 and computer data station PE 6200. The wavelength for chromium was 357.9 nm. Mean renal clearance value during the dialysis was 24.98 mL/min (SD 2.984). In that time mean dialysance value was 8.96 mL/min (SD 1.84). After the completion of dialysis forced diuresis alone was proceeded for another 33 hours. In that time chromium renal clearance was measured three times (after first 9 hours and then in two 12-hour cycles). Mean renal clearance value was 18.7 mL/min (SD 10.27). In that time a small increase in plasma urea and creatinine levels was shown in lab tests. Urine output was appropriate. The patient was discharged after 17 days of treatment. Conclusion: Kinetics of chromium elimination presented in our report proved that hemodialysis and forced diuresis are of low efficiency. However, three-fold increase in chromium renal clearance suggests that forced diuresis should be taken into consideration as a method of treatment in early chromium intoxication. Renal sufficiency is absolutely necessary for this kind of treatment.","Toxicokinetics of Chromium Elimination in Hemodialysis and Forced Diuresis Based on a Case of Potassium Dichromate Intoxication Abs: Objective: In the toxicological literature there is no one defined and commonly accepted standard concerning chromium intoxication treatment. The question of administrating elimination procedures (hemodialysis, forced diuresis) in such cases is especially controversial. The aim of this report is a comparative study of the effectiveness of hemodialysis and forced diuresis as the methods of treatment in acute potassium dichromate poisoning. Case Report: A 54-years-old patient accidentally drank an aqueous solution of wood preservative. The main ingredient of the solution was potassium dichromate. It was impossible to specify neither the exact volume of the drunken liquid or the concentration of the active agent. The patient drank water and provoked vomiting immediately after the intake of the solution. Patient?s general state on admission (4 hours after the intoxication) was quite good. He complained of abdominal pain, nausea and a burning sensation localised along the oesophagus. The patient was vomiting gastric contents with a considerable amount of blood. Urine output was appropriate, lab tests were normal, not suggestive of renal failure. An 8-hour hemodialysis together with forced diuresis were initiated approximately one hour after admission. Cuprofan dialysator of the surface of 1.6 m2 was used, blood flow (Qb) was 200 mL/min, dialysate flow (Qd) 616 mL/min. Renal clearance for chromium and dialysance were checked every 2 hours during the dialysis. Chromium levels in plasma, urine and dialysate samples were determined by graphite furnace atomic absorption spectrophotometry using Perkin Elmer model 4100 ZL Zeeman with an autosampler AS-70 and computer data station PE 6200. The wavelength for chromium was 357.9 nm. Mean renal clearance value during the dialysis was 24.98 mL/min (SD 2.984). In that time mean dialysance value was 8.96 mL/min (SD 1.84). After the completion of dialysis forced diuresis alone was proceeded for another 33 hours. In that time chromium renal clearance was measured three times (after first 9 hours and then in two 12-hour cycles). Mean renal clearance value was 18.7 mL/min (SD 10.27). In that time a small increase in plasma urea and creatinine levels was shown in lab tests. Urine output was appropriate. The patient was discharged after 17 days of treatment. Conclusion: Kinetics of chromium elimination presented in our report proved that hemodialysis and forced diuresis are of low efficiency. However, three-fold increase in chromium renal clearance suggests that forced diuresis should be taken into consideration as a method of treatment in early chromium intoxication. Renal sufficiency is absolutely necessary for this kind of treatment."
1238534,Arreola-Mendoza et al. 2004,Acute Renal Failure Induced By Chromate Treatment And Claudin-2 Expression In Murine Kidney,"Renal epithelia and endothelia have tight junctions (TJs) that regulate the passage of ions, water and molecules through the paracellular pathway. Integrity of TJs is responsible for the passive permeability of polarized epithelia. Chromate (Cr6+) administration induces nephrotoxicity in humans and experimental models. It also increases formation of reactive oxygen species and oxidative damage. Oxidative stress compromises TJs, but the mechanisms are unknown. Our objective was to study the oxidative damage and effects on renal function and structure of TJs induced by chromate administration. Wistar female rats received potassium dichromate (15 mg/kg, SC, single dose). Renal function, lipid peroxidation, and claudin- 2 (a protein of TJs) immunohistochemical pattern were monitored on days 0, 1, 2, 3, 7, 10 y 14. Confocal microscopy immunofluorescence of claudin-2 showed a clear presence at the cell borders of proximal tubules. This pattern was severely disorganized after chromate administration with spontaneous recovery after day 7. In agreement with morphological alterations, renal function was maximally altered on day 3 and thereafter recovery ensued. Glomerular filtration decreased and glucose and sodium fractional excretions increased. Oxidative damage showed a similar time-course. Our results suggest that chromate administration induces acute renal failure, oxidative damage and disorganization of the claudin-2 renal pattern.","Acute Renal Failure Induced By Chromate Treatment And Claudin-2 Expression In Murine Kidney Abs: Renal epithelia and endothelia have tight junctions (TJs) that regulate the passage of ions, water and molecules through the paracellular pathway. Integrity of TJs is responsible for the passive permeability of polarized epithelia. Chromate (Cr6+) administration induces nephrotoxicity in humans and experimental models. It also increases formation of reactive oxygen species and oxidative damage. Oxidative stress compromises TJs, but the mechanisms are unknown. Our objective was to study the oxidative damage and effects on renal function and structure of TJs induced by chromate administration. Wistar female rats received potassium dichromate (15 mg/kg, SC, single dose). Renal function, lipid peroxidation, and claudin- 2 (a protein of TJs) immunohistochemical pattern were monitored on days 0, 1, 2, 3, 7, 10 y 14. Confocal microscopy immunofluorescence of claudin-2 showed a clear presence at the cell borders of proximal tubules. This pattern was severely disorganized after chromate administration with spontaneous recovery after day 7. In agreement with morphological alterations, renal function was maximally altered on day 3 and thereafter recovery ensued. Glomerular filtration decreased and glucose and sodium fractional excretions increased. Oxidative damage showed a similar time-course. Our results suggest that chromate administration induces acute renal failure, oxidative damage and disorganization of the claudin-2 renal pattern."
1238533,Holmes et al. 2004,Lead Chromate-Induced Cytotoxicity In Human Bronchial Cells Is Mediated By Extracellular Chromium,"Hexavalent chromium (Cr(VI)) compounds are established human lung carcinogens and solubility plays a key role in the carcinogenicity of Cr(VI), with the most potent carcinogens being the particulate Cr(VI) compounds. Lead chromate (LC) is often used as a prototypical particulate Cr(VI) compound since it is the most insoluble of these compounds; however, it is unknown whether chromium (Cr), lead (Pb), or a combination is responsible for the cytotoxic effects of LC. We compared the cytotoxicity and ion uptake of LC with sodium chromate (SC) and lead glutamate (LG) in WTHBF-6 cells, and the effects of co-treating LC, SC and LG with vitamin C to evaluate changes in cytotoxicity and ion uptake since vitamin C is known to reduce Cr(IV) to Cr(III) and prevent chromium uptake. LC and SC both induced concentration-dependent increases in cytotoxicity at similar intracellular Cr concentrations. LC at 0.1 and 5 ug/cm2 induced 85 and 3% relative survival at intracellular concentrations of 1.3 and 16.7 uM respectively, while 1 and 5 uM SC induced 75 and 3% relative survival with intracellular concentrations of 1.7 and 15.2 uM respectively. Co-treating LC or SC with vitamin C dramatically reduced intracellular Cr concentrations and cytotoxicity. LG also induced a concentrationdependent increase in cytotoxicity, but 200 and 1000 uM LG induced 86 and 62% relative survival at an intracellular Pb concentration of 4.4 and 48.3 uM respectively, while 5 ug/cm2 LC induced 3% relative survival with an intracellular Pb concentration of only 2.9 uM. Co-treating LG with vitamin C had no effect on the cytotoxicity or intracellular Pb concentrations. Cytotoxicity and intracellular Pb concentrations decreased when LC was co-treated with vitamin C 5 ug/cm2. These data indicate that Cr and not Pb mediates LC-induced cytotoxicity in human bronchial cells.","Lead Chromate-Induced Cytotoxicity In Human Bronchial Cells Is Mediated By Extracellular Chromium Abs: Hexavalent chromium (Cr(VI)) compounds are established human lung carcinogens and solubility plays a key role in the carcinogenicity of Cr(VI), with the most potent carcinogens being the particulate Cr(VI) compounds. Lead chromate (LC) is often used as a prototypical particulate Cr(VI) compound since it is the most insoluble of these compounds; however, it is unknown whether chromium (Cr), lead (Pb), or a combination is responsible for the cytotoxic effects of LC. We compared the cytotoxicity and ion uptake of LC with sodium chromate (SC) and lead glutamate (LG) in WTHBF-6 cells, and the effects of co-treating LC, SC and LG with vitamin C to evaluate changes in cytotoxicity and ion uptake since vitamin C is known to reduce Cr(IV) to Cr(III) and prevent chromium uptake. LC and SC both induced concentration-dependent increases in cytotoxicity at similar intracellular Cr concentrations. LC at 0.1 and 5 ug/cm2 induced 85 and 3% relative survival at intracellular concentrations of 1.3 and 16.7 uM respectively, while 1 and 5 uM SC induced 75 and 3% relative survival with intracellular concentrations of 1.7 and 15.2 uM respectively. Co-treating LC or SC with vitamin C dramatically reduced intracellular Cr concentrations and cytotoxicity. LG also induced a concentrationdependent increase in cytotoxicity, but 200 and 1000 uM LG induced 86 and 62% relative survival at an intracellular Pb concentration of 4.4 and 48.3 uM respectively, while 5 ug/cm2 LC induced 3% relative survival with an intracellular Pb concentration of only 2.9 uM. Co-treating LG with vitamin C had no effect on the cytotoxicity or intracellular Pb concentrations. Cytotoxicity and intracellular Pb concentrations decreased when LC was co-treated with vitamin C 5 ug/cm2. These data indicate that Cr and not Pb mediates LC-induced cytotoxicity in human bronchial cells."
1238532,Wise et al. 2004,Comparative chromium toxicity in cultured bowhead whale and human lung cells,"Bowhead whales live 150-200 years and yet do not appear to get cancer. This is remarkable given that bowhead whales are routinely exposed to, and bioaccumulate, high levels of metals. We have established bowhead whale lung cell lines to compare their cellular responses to metals to those of human cells. Hexavalent chromium (Cr(VI)) is a metal of particular concern and has long been recognized to cause human lung cancer. Studies have shown that it is the insoluble forms of Cr(VI) that are the most potent carcinogens. In humans, these particles dissolve outside the cell. We found that the particulate form of Cr(VI) was more cytotoxic to bowhead cells than to human cells. For example, 0.1, 0.5, 1 and 5 ug/cm2 lead chromate induced 39, 20, 7 and 0% relative survival in bowhead cells and 90, 71, 43 and 15% relative survival in human cells at the same concentrations. By contrast, we found that the soluble form of Cr(VI) was more cytotoxic to human cells than to bowhead cells. 1, 2.5, 5 and 10 uM sodium chromate (SC) induced 63, 42, 8 and 0% relative survival in human cells and 98, 96, 62 and 3% relative survival in bowhead cells. Human cells treated with SC had intracellular chromium concentrations of 1.81, 3.84, 7.71 and 15.41 uM at treatment concentrations of 1, 2.5, 5 and 10uM, while bowhead cells had intracellular concentrations of 3.54, 9.16, 14.99 and 29.25 uM at the same treatment concentrations. By measuring the toxicity of chromium in human and bowhead lung cells we can start to understand the differences in these species biological response to environmental insult. Further research is needed to elucidate the differences in the cellular responses to soluble versus insoluble chromium and to look at the biochemical mechanisms in the responses of both cell types to chromium.","Comparative chromium toxicity in cultured bowhead whale and human lung cells Abs: Bowhead whales live 150-200 years and yet do not appear to get cancer. This is remarkable given that bowhead whales are routinely exposed to, and bioaccumulate, high levels of metals. We have established bowhead whale lung cell lines to compare their cellular responses to metals to those of human cells. Hexavalent chromium (Cr(VI)) is a metal of particular concern and has long been recognized to cause human lung cancer. Studies have shown that it is the insoluble forms of Cr(VI) that are the most potent carcinogens. In humans, these particles dissolve outside the cell. We found that the particulate form of Cr(VI) was more cytotoxic to bowhead cells than to human cells. For example, 0.1, 0.5, 1 and 5 ug/cm2 lead chromate induced 39, 20, 7 and 0% relative survival in bowhead cells and 90, 71, 43 and 15% relative survival in human cells at the same concentrations. By contrast, we found that the soluble form of Cr(VI) was more cytotoxic to human cells than to bowhead cells. 1, 2.5, 5 and 10 uM sodium chromate (SC) induced 63, 42, 8 and 0% relative survival in human cells and 98, 96, 62 and 3% relative survival in bowhead cells. Human cells treated with SC had intracellular chromium concentrations of 1.81, 3.84, 7.71 and 15.41 uM at treatment concentrations of 1, 2.5, 5 and 10uM, while bowhead cells had intracellular concentrations of 3.54, 9.16, 14.99 and 29.25 uM at the same treatment concentrations. By measuring the toxicity of chromium in human and bowhead lung cells we can start to understand the differences in these species biological response to environmental insult. Further research is needed to elucidate the differences in the cellular responses to soluble versus insoluble chromium and to look at the biochemical mechanisms in the responses of both cell types to chromium."
1238531,Morin et al. 2004,Metal Toxicity Of Sodium Chromate In Steller Sea Lion Bronchus And Dermis Compared To Humans,"Hexavalent chromium (Cr(VI)) is a known carcinogen to humans. Some species of marine mammals are known to be more resistant to the effects of this and other xenobiotics than humans. For example, Cr(VI) has been shown to cause cancer in humans, but relatively higher levels of chromium and other metals have been found in tissues from many populations of marine mammals without increasing incidences of pathologies. Therefore, the focus of this investigation was to explore the possibility that sea lion cells respond differently than human cells to the cytotoxic effect of Cr(VI). We found that concentrations of 1, 2.5, 5, 10, and 25 uM sodium chromate induced 63, 42, 8, 0, and 0% relative survival in human bronchial fibroblasts (WTHBF-6) when compared to untreated controls, and that these same concentrations induced 67, 54, 41, 25 and 1% relative survival in Steller sea lion bronchial fibroblasts. Similarly, concentrations of 1, 2.5, 5, 10, and 25 uM sodium chromate induced 56, 28, 11, 0, and 0% relative survival in human dermal fibroblasts (BJ-htert) when compared to untreated controls; whereas the same concentrations induced 89, 76, 64, 37, and 24% relative survival in Steller sea lion dermal fibroblasts. This suggests that at low and moderate concentrations Sea lion cells may have protective mechanisms for the cytotoxic effects of Cr(VI). Further research is aimed at understanding the mechanism of this.","Metal Toxicity Of Sodium Chromate In Steller Sea Lion Bronchus And Dermis Compared To Humans Abs: Hexavalent chromium (Cr(VI)) is a known carcinogen to humans. Some species of marine mammals are known to be more resistant to the effects of this and other xenobiotics than humans. For example, Cr(VI) has been shown to cause cancer in humans, but relatively higher levels of chromium and other metals have been found in tissues from many populations of marine mammals without increasing incidences of pathologies. Therefore, the focus of this investigation was to explore the possibility that sea lion cells respond differently than human cells to the cytotoxic effect of Cr(VI). We found that concentrations of 1, 2.5, 5, 10, and 25 uM sodium chromate induced 63, 42, 8, 0, and 0% relative survival in human bronchial fibroblasts (WTHBF-6) when compared to untreated controls, and that these same concentrations induced 67, 54, 41, 25 and 1% relative survival in Steller sea lion bronchial fibroblasts. Similarly, concentrations of 1, 2.5, 5, 10, and 25 uM sodium chromate induced 56, 28, 11, 0, and 0% relative survival in human dermal fibroblasts (BJ-htert) when compared to untreated controls; whereas the same concentrations induced 89, 76, 64, 37, and 24% relative survival in Steller sea lion dermal fibroblasts. This suggests that at low and moderate concentrations Sea lion cells may have protective mechanisms for the cytotoxic effects of Cr(VI). Further research is aimed at understanding the mechanism of this."
1238530,Goertz et al. 2004,Sodium Chromate And Cadmium Chloride Toxicity In Steller Sea Lion Cells,"The Western population of the Steller sea lion is endangered and the cause is unknown. We are investigating the hypothesis that metals might be a factor in this decline. We find that metals are toxic to Steller sea lion cells in an organ and metal specific manner. For example, chromium induced concentration-dependent cytotoxicity in dermal, renal, bronchial and testicular fibroblasts. 2.5, 5, 10, and 25 uM sodium chromate induced 92, 73, 29, and 1% relative survival in kidney cells; 76, 64, 37, and 24% relative survival in dermal fibroblasts; and 54, 41, 25, and 1% relative survival in bronchial cells. Testicular cells had 22 and 1% relative survival at 2.5 and 5uM, and no survival at higher doses. Thus, testicular cells were the most sensitive, dermis most resistant, and bronchial and renal cells were intermediate. Cadmium was generally less toxic than chromium at all doses studied in these tissues. Cadmium chloride concentrations of 2.5, 5, 10, and 25 uM induced 77, 53, 40, and 30% relative survival in kidney cells; 121, 98, 82, and 81% relative survival in dermal fibroblasts; 84, 76, 57, and 52% relative survival in bronchial cells; and 65, 63, 54, and 27% survival in testicular cells. It is noteworthy that testicular cells were the most sensitive to both of these metals which has implications concerning possible transgenerational effects of metal exposure. Current efforts include evaluating tissue loads of metals in Steller sea lion tissue to compare with the intracellular loads in cell lines at toxic concentrations, and understanding the genotoxic effects of metals. Further research is aimed at testing additional metals and extending the lifespan of these cells in culture with telomerase.","Sodium Chromate And Cadmium Chloride Toxicity In Steller Sea Lion Cells Abs: The Western population of the Steller sea lion is endangered and the cause is unknown. We are investigating the hypothesis that metals might be a factor in this decline. We find that metals are toxic to Steller sea lion cells in an organ and metal specific manner. For example, chromium induced concentration-dependent cytotoxicity in dermal, renal, bronchial and testicular fibroblasts. 2.5, 5, 10, and 25 uM sodium chromate induced 92, 73, 29, and 1% relative survival in kidney cells; 76, 64, 37, and 24% relative survival in dermal fibroblasts; and 54, 41, 25, and 1% relative survival in bronchial cells. Testicular cells had 22 and 1% relative survival at 2.5 and 5uM, and no survival at higher doses. Thus, testicular cells were the most sensitive, dermis most resistant, and bronchial and renal cells were intermediate. Cadmium was generally less toxic than chromium at all doses studied in these tissues. Cadmium chloride concentrations of 2.5, 5, 10, and 25 uM induced 77, 53, 40, and 30% relative survival in kidney cells; 121, 98, 82, and 81% relative survival in dermal fibroblasts; 84, 76, 57, and 52% relative survival in bronchial cells; and 65, 63, 54, and 27% survival in testicular cells. It is noteworthy that testicular cells were the most sensitive to both of these metals which has implications concerning possible transgenerational effects of metal exposure. Current efforts include evaluating tissue loads of metals in Steller sea lion tissue to compare with the intracellular loads in cell lines at toxic concentrations, and understanding the genotoxic effects of metals. Further research is aimed at testing additional metals and extending the lifespan of these cells in culture with telomerase."
1238529,Costa et al. 2004,Chromium(VI) In Drinking Water Increases The Incidence Of UV-Induced Skin Tumors In Hairless Mice,"Hexavalent chromium (Cr(VI)) is a well known human carcinogen with exposures occurring in both occupational and environmental settings. Although lung carcinogenicity has been well documented for exposure via inhalation, the cancer-causing potential of Cr(VI) in drinking water has been much more controversial. Human exposure to chromium compounds alone is not relevant in the scenario of our daily lives, since we are exposed to many different toxicologically active environmental insults. We used a hairless mouse model to study the effects of Cr(VI) exposure via drinking water on ultraviolet radiation(UVR)-induced skin tumors. Hairless mice were divided into seven groups: control, UVR alone, 2.5ppm K2CrO4, 5.0ppm K2CrO4, UVR(1.2 KJ/m2) + 0.5ppm K2CrO4, UVR + 2.5 K2CrO4, and UVR + 5.0ppm K2CrO4. Mice were inspected weekly for the appearance of skin tumors larger than 2mm. Mice were sacrificed on day 182 and skin tumors were removed for histopathological analysis. No skin tumors were observed in the control or chromium only exposure groups. There was a dose dependent increase in the number of skin tumors greater than 2mm for mice exposed to Cr(VI) and UV when compared to mice exposed to UV alone. The increase in tumors larger than 2mm was significant for UV + the two higher doses of K2CrO4. Malignant tumors were observed in all UV treated mice and there was a statistically significant increase in the numbers of malignant tumors for the UVR plus K2CrO4(5ppm) group. Exposure to Cr(VI) via drinking water exposure has been a significant public health concern and drinking water standards have been set based on exposure to chromium alone. The data presented here indicate that Cr(VI) can increase the number of UV induced tumors in a dose dependent manner. This suggests that human exposure to Cr(VI) may increase the risk of carcinogenesis for other agents as well. Our results have important implications for risk assessment and suggest that the current drinking water standards for Cr(VI) exposure should be reassessed and adjusted downward.","Chromium(VI) In Drinking Water Increases The Incidence Of UV-Induced Skin Tumors In Hairless Mice Abs: Hexavalent chromium (Cr(VI)) is a well known human carcinogen with exposures occurring in both occupational and environmental settings. Although lung carcinogenicity has been well documented for exposure via inhalation, the cancer-causing potential of Cr(VI) in drinking water has been much more controversial. Human exposure to chromium compounds alone is not relevant in the scenario of our daily lives, since we are exposed to many different toxicologically active environmental insults. We used a hairless mouse model to study the effects of Cr(VI) exposure via drinking water on ultraviolet radiation(UVR)-induced skin tumors. Hairless mice were divided into seven groups: control, UVR alone, 2.5ppm K2CrO4, 5.0ppm K2CrO4, UVR(1.2 KJ/m2) + 0.5ppm K2CrO4, UVR + 2.5 K2CrO4, and UVR + 5.0ppm K2CrO4. Mice were inspected weekly for the appearance of skin tumors larger than 2mm. Mice were sacrificed on day 182 and skin tumors were removed for histopathological analysis. No skin tumors were observed in the control or chromium only exposure groups. There was a dose dependent increase in the number of skin tumors greater than 2mm for mice exposed to Cr(VI) and UV when compared to mice exposed to UV alone. The increase in tumors larger than 2mm was significant for UV + the two higher doses of K2CrO4. Malignant tumors were observed in all UV treated mice and there was a statistically significant increase in the numbers of malignant tumors for the UVR plus K2CrO4(5ppm) group. Exposure to Cr(VI) via drinking water exposure has been a significant public health concern and drinking water standards have been set based on exposure to chromium alone. The data presented here indicate that Cr(VI) can increase the number of UV induced tumors in a dose dependent manner. This suggests that human exposure to Cr(VI) may increase the risk of carcinogenesis for other agents as well. Our results have important implications for risk assessment and suggest that the current drinking water standards for Cr(VI) exposure should be reassessed and adjusted downward."
1238528,Rodriguez et al. 2007,"Chromium toxicity induces ovarian follicular developmental arrest, apoptosis, and deregulated steroidogenesis: Vitamin c restores follicular survival and function","Chromium (Cr) has been used in wide-range of industries for more than a century. Cr exists in the environment as two major valence states Cr(III) and Cr(VI). Cr(III) is an essential nutrient whereas Cr (VI) is highly toxic and a strong oxidizing mediator. Millions of people, and majority of industrial workers, worldwide are exposed to Cr(VI) during their life time. Soluble Cr(VI) is rapidly transported inside the cell by anion transport mechanisms, and it persists as non-biodegradable mediator intracellularly and leads to multiple cellular dysfunctions that include DNA adduct formation, deregulated cell cycle, apoptosis and carcinogenesis. Vitamin C and antioxidants protect the cells from Cr toxicity. Interestingly, Cr(VI) exposure adversely affects the reproductive functions. We hypothesize that: (1) exposure to chromium impairs follicular development and ovarian functions; and (2) vitamin C reverses the effects of chromium toxicity on follicular development and ovarian functions. The objectives were to determine the effects of Cr(VI) and reversal effect of vitamin C on chromium toxicity on: (1) ovarian cycle and puberty; (2) ovarian follicular development and atresia/apoptosis and (3) ovarian steroid production. We used rat as in vivo model and immortalized rat granulosa cells (SIGC) as in vitro model. Study 1: Rats (n=6) were treated with potassium dichromate (PCr), a Cr(VI) component, 200ppm, through drinking water from days 9 to 21 of pregnancy. After delivery the mothers were continued on PCr until weaning of pups, afterwards the pups were maintained on PCr up to 65 days of age. Study 2: Rats (n=6) received similar PCr treatment regimen along with vitamin C. Study 3: Rats (n=6) served as control. Rats were killed on days 0, 3, 7, 18, 45 and 65 of age. Serum and ovarian tissue levels of Cr were estimated. Follicular development and atresia were assessed. Plasma concentrations of progesterone (P4) and estradiol (E2) were measured. Study 4: Granulosa cells were treated with PCr (25uM) for 0, 12 and 24h in the presence or absence of vitamin C and cell proliferation, apoptosis and steroidogenesis were studied. Expression of steroidogenic acute regulatory protein (StAR), P450 aromatase and steroidogenic factor-1 (SF-1) mRNAs were studied by RT-PCR. Activation of caspase 3 and PARP proteins were studied by western blot. Cr exposure resulted in: (1) accumulation of Cr in blood and ovarian tissues; (2) extended the estrous cycle and induced irregular cyclicity; (3) delayed the onset of puberty; (4) induced follicular atresia, impaired the growth, development and differentiation of the granulosa and theca cells of ovarian follicles, and induced fibrosis and necrosis of primary and secondary follicles; (5) decreased plasma concentrations of P4 and E2; (6) decreased proliferation and increased apoptosis of granulosa cells; (7) induced caspase 3 and PARP activation in granulosa cells, and (8) altered the expression profile of StAR, P450 aromatase and SF-1 in granulosa cells. Vitamin C partially (75%) reversed the effects of Cr on the above end-points studied. In summary, Cr toxicity arrests the follicular development and altered steroid biosynthesis, cyclicity and puberty in female rats. Cr toxicity induced granulosa cell apoptosis might be mediated through caspase 3 / PARP pathways. Vitamin C protects the ovarian follicle from Cr induced damage. These results may suggest that exposure to Cr is hostile to reproductive health of women.","Chromium toxicity induces ovarian follicular developmental arrest, apoptosis, and deregulated steroidogenesis: Vitamin c restores follicular survival and function Abs: Chromium (Cr) has been used in wide-range of industries for more than a century. Cr exists in the environment as two major valence states Cr(III) and Cr(VI). Cr(III) is an essential nutrient whereas Cr (VI) is highly toxic and a strong oxidizing mediator. Millions of people, and majority of industrial workers, worldwide are exposed to Cr(VI) during their life time. Soluble Cr(VI) is rapidly transported inside the cell by anion transport mechanisms, and it persists as non-biodegradable mediator intracellularly and leads to multiple cellular dysfunctions that include DNA adduct formation, deregulated cell cycle, apoptosis and carcinogenesis. Vitamin C and antioxidants protect the cells from Cr toxicity. Interestingly, Cr(VI) exposure adversely affects the reproductive functions. We hypothesize that: (1) exposure to chromium impairs follicular development and ovarian functions; and (2) vitamin C reverses the effects of chromium toxicity on follicular development and ovarian functions. The objectives were to determine the effects of Cr(VI) and reversal effect of vitamin C on chromium toxicity on: (1) ovarian cycle and puberty; (2) ovarian follicular development and atresia/apoptosis and (3) ovarian steroid production. We used rat as in vivo model and immortalized rat granulosa cells (SIGC) as in vitro model. Study 1: Rats (n=6) were treated with potassium dichromate (PCr), a Cr(VI) component, 200ppm, through drinking water from days 9 to 21 of pregnancy. After delivery the mothers were continued on PCr until weaning of pups, afterwards the pups were maintained on PCr up to 65 days of age. Study 2: Rats (n=6) received similar PCr treatment regimen along with vitamin C. Study 3: Rats (n=6) served as control. Rats were killed on days 0, 3, 7, 18, 45 and 65 of age. Serum and ovarian tissue levels of Cr were estimated. Follicular development and atresia were assessed. Plasma concentrations of progesterone (P4) and estradiol (E2) were measured. Study 4: Granulosa cells were treated with PCr (25uM) for 0, 12 and 24h in the presence or absence of vitamin C and cell proliferation, apoptosis and steroidogenesis were studied. Expression of steroidogenic acute regulatory protein (StAR), P450 aromatase and steroidogenic factor-1 (SF-1) mRNAs were studied by RT-PCR. Activation of caspase 3 and PARP proteins were studied by western blot. Cr exposure resulted in: (1) accumulation of Cr in blood and ovarian tissues; (2) extended the estrous cycle and induced irregular cyclicity; (3) delayed the onset of puberty; (4) induced follicular atresia, impaired the growth, development and differentiation of the granulosa and theca cells of ovarian follicles, and induced fibrosis and necrosis of primary and secondary follicles; (5) decreased plasma concentrations of P4 and E2; (6) decreased proliferation and increased apoptosis of granulosa cells; (7) induced caspase 3 and PARP activation in granulosa cells, and (8) altered the expression profile of StAR, P450 aromatase and SF-1 in granulosa cells. Vitamin C partially (75%) reversed the effects of Cr on the above end-points studied. In summary, Cr toxicity arrests the follicular development and altered steroid biosynthesis, cyclicity and puberty in female rats. Cr toxicity induced granulosa cell apoptosis might be mediated through caspase 3 / PARP pathways. Vitamin C protects the ovarian follicle from Cr induced damage. These results may suggest that exposure to Cr is hostile to reproductive health of women."
1238527,Sheiko et al. 2001,,, Abs: 
1238524,El-Tawil and  Morgan 2000,Assessment of the teratogenicity of trivalent and hexavalent chromium compounds in female rabbits,"The exposure of pregnant female rabbits to trivalent (chromium chloride) or hexavalent (potassium dichromate) chromium compounds in drinking water (500 ppm) during the organogenesis period (6-18th day of gestation) revealed embryotoxic - and fetotoxic effects. Both trivalent and hexavalent compounds induced dwarfism, kinky and short tail and a significant reduction in the number of implantation sites and in the number of viable fetuses. The number of females with resorption was significantly increased in the hexavalent-exposed group. Visceral abnormalities in the form of lung hypoplasia, heart hypertrophy, intrathoracic hemorrhage and dilated nares and brain lateral ventricles were found in the fetuses of both chromium (III, VI) treated mothers. Skeletal anomalies (reduced number of sternal and caudal bones) were also recorded in both chromium groups. Furthermore, reduced ossification in parietal and inerparietal bones was significantly increased in the hexavalent chromium exposed females. Chromium levels in blood, placenta and fetuses significantly increased in both chromium groups. In conclusion, the exposure of pregnant rabbits to trivalent and hexavalent chromium compounds would have adverse effects on the embryonic and fetal development.","Assessment of the teratogenicity of trivalent and hexavalent chromium compounds in female rabbits Abs: The exposure of pregnant female rabbits to trivalent (chromium chloride) or hexavalent (potassium dichromate) chromium compounds in drinking water (500 ppm) during the organogenesis period (6-18th day of gestation) revealed embryotoxic - and fetotoxic effects. Both trivalent and hexavalent compounds induced dwarfism, kinky and short tail and a significant reduction in the number of implantation sites and in the number of viable fetuses. The number of females with resorption was significantly increased in the hexavalent-exposed group. Visceral abnormalities in the form of lung hypoplasia, heart hypertrophy, intrathoracic hemorrhage and dilated nares and brain lateral ventricles were found in the fetuses of both chromium (III, VI) treated mothers. Skeletal anomalies (reduced number of sternal and caudal bones) were also recorded in both chromium groups. Furthermore, reduced ossification in parietal and inerparietal bones was significantly increased in the hexavalent chromium exposed females. Chromium levels in blood, placenta and fetuses significantly increased in both chromium groups. In conclusion, the exposure of pregnant rabbits to trivalent and hexavalent chromium compounds would have adverse effects on the embryonic and fetal development."
1238523,El-Tawil and  Morgan 2000,Teratogenic effect of trivalent and hexavalent chromium in rabbits,"Chromium is considered to be an essential nutrient that helps to maintain normal metabolism of glucose, cholesterol, and fat in humans. Studies in the literature indicate that hexavalent chromium (Cr-VI) is more toxic than trivalent chromium (Cr-III) as it is actively transported across the plasma membranes and is reduced via unstable reactive intermediate to Cr-III. Also, the published data indicate that exposure to Cr-VI decrease the number of viable fetuses and increase the number of dead ones. In the current investigation pregnant rabbits were exposed to Cr-III (chromium chloride), or Cr-IV (potassium dichromate) in drinking water at a dose of 500 ppm each during the organogenesis period. Exposure to Cr-IV significantly increased the number of resorption sites and decreased the number of viable fetuses compared to Cr-III and control groups. Exposure to either chemicals induced dwarfism, kinky and short tails, lung hypoplasia, heart hypertrophy, intrathoracic hemorrhage and dilated nares and brain lateral ventricles. Furthermore, reduced ossification in parietal and inerparietal bones was significantly increased in the fetuses from the females exposed to Cr-VI. The results of the current investigation may indicate that both Cr-III and Cr-VI are teratogenic for the tested concentration. However, the severity of effects are higher with the exposure to Cr-VI.","Teratogenic effect of trivalent and hexavalent chromium in rabbits Abs: Chromium is considered to be an essential nutrient that helps to maintain normal metabolism of glucose, cholesterol, and fat in humans. Studies in the literature indicate that hexavalent chromium (Cr-VI) is more toxic than trivalent chromium (Cr-III) as it is actively transported across the plasma membranes and is reduced via unstable reactive intermediate to Cr-III. Also, the published data indicate that exposure to Cr-VI decrease the number of viable fetuses and increase the number of dead ones. In the current investigation pregnant rabbits were exposed to Cr-III (chromium chloride), or Cr-IV (potassium dichromate) in drinking water at a dose of 500 ppm each during the organogenesis period. Exposure to Cr-IV significantly increased the number of resorption sites and decreased the number of viable fetuses compared to Cr-III and control groups. Exposure to either chemicals induced dwarfism, kinky and short tails, lung hypoplasia, heart hypertrophy, intrathoracic hemorrhage and dilated nares and brain lateral ventricles. Furthermore, reduced ossification in parietal and inerparietal bones was significantly increased in the fetuses from the females exposed to Cr-VI. The results of the current investigation may indicate that both Cr-III and Cr-VI are teratogenic for the tested concentration. However, the severity of effects are higher with the exposure to Cr-VI."
1238521,Hassett-Sipple et al. 1997,Mercury study report to Congress. Health effects of mercury and mercury compounds,"Section 112(n)(1)(B) of the Clean Air Act (CAA), as amended in 1990, directs the U.S. Environmental Protection Agency (U.S. EPA) to submit to Congress a comprehensive study on atmospheric emissions of mercury. This document, which covers the human health effects of mercury and mercury compounds, is one volume of U.S. EPA's eight-volume Report in response to this directive. Mercury is a naturally occurring element that is found in air, water and soil. It exists in any of three valence states: Hg0 (elemental mercury), Hg2(2+) (mercurous mercury), or Hg2+ (mercuric mercury). Most of the population of the earth have some exposure to mercury as a result of normal daily activities. The general population may be exposed to mercury through inhalation of ambient air, consumption of contaminated food, water, or soil; and/or dermal exposure to substances containing mercury. In addition, some quantity of mercury is released from dental amalgam. The health effects literature contains many investigations of populations with potentially high exposure to mercury, including industrial workers, people living near point sources of mercury emissions, people who consume large amounts of fish, and dental professionals. There also are numerous studies of populations unintentionally exposed to high levels of mercury, such as the Minamata poisoning episode in Japan. Volume IV (An Assessment Exposure to Mercury in the United States) presents measured and predicted mercury exposure for various U.S. populations. The purpose of this volume, Volume V, is to summarize the available health effects information for mercury and mercury compounds and to present U.S. EPA's analysis for two critical pieces of the risk assessment paradigm described by the National Academy of Sciences in 1983. Specifically, this volume contains the hazard identification and dose-response assessments for three forms of mercury: elemental mercury, mercuric chloride (inorganic mercury), and methylmercury (organic mercury). In order to characterize risk for any populations, the evaluations presented in this volume must be combined with the assessment of exposure presented in Volume IV. Volume V is not intended to be an exhaustive survey of the voluminous health effects literature available for mercury. Rather, the purpose is to present a brief survey of the studies relevant for assessing potential human health effects and to present more detailed information on those studies which form the basis for U.S. EPA's hazard identification and dose-response assessments. The three forms of mercury which are emphasized in this volume were selected based on data indicating that these are the predominant forms of mercury to which humans are exposed. In addition, examination of the published literature indicates that most health data are on these forms. It is acknowledged that certain populations can be exposed to many types of organic mercurials, such as antiseptics and pesticides. Volume V, however, deals with methylmercury except in cases where information on another organic is presented for illustrative purposes.","Mercury study report to Congress. Health effects of mercury and mercury compounds Abs: Section 112(n)(1)(B) of the Clean Air Act (CAA), as amended in 1990, directs the U.S. Environmental Protection Agency (U.S. EPA) to submit to Congress a comprehensive study on atmospheric emissions of mercury. This document, which covers the human health effects of mercury and mercury compounds, is one volume of U.S. EPA's eight-volume Report in response to this directive. Mercury is a naturally occurring element that is found in air, water and soil. It exists in any of three valence states: Hg0 (elemental mercury), Hg2(2+) (mercurous mercury), or Hg2+ (mercuric mercury). Most of the population of the earth have some exposure to mercury as a result of normal daily activities. The general population may be exposed to mercury through inhalation of ambient air, consumption of contaminated food, water, or soil; and/or dermal exposure to substances containing mercury. In addition, some quantity of mercury is released from dental amalgam. The health effects literature contains many investigations of populations with potentially high exposure to mercury, including industrial workers, people living near point sources of mercury emissions, people who consume large amounts of fish, and dental professionals. There also are numerous studies of populations unintentionally exposed to high levels of mercury, such as the Minamata poisoning episode in Japan. Volume IV (An Assessment Exposure to Mercury in the United States) presents measured and predicted mercury exposure for various U.S. populations. The purpose of this volume, Volume V, is to summarize the available health effects information for mercury and mercury compounds and to present U.S. EPA's analysis for two critical pieces of the risk assessment paradigm described by the National Academy of Sciences in 1983. Specifically, this volume contains the hazard identification and dose-response assessments for three forms of mercury: elemental mercury, mercuric chloride (inorganic mercury), and methylmercury (organic mercury). In order to characterize risk for any populations, the evaluations presented in this volume must be combined with the assessment of exposure presented in Volume IV. Volume V is not intended to be an exhaustive survey of the voluminous health effects literature available for mercury. Rather, the purpose is to present a brief survey of the studies relevant for assessing potential human health effects and to present more detailed information on those studies which form the basis for U.S. EPA's hazard identification and dose-response assessments. The three forms of mercury which are emphasized in this volume were selected based on data indicating that these are the predominant forms of mercury to which humans are exposed. In addition, examination of the published literature indicates that most health data are on these forms. It is acknowledged that certain populations can be exposed to many types of organic mercurials, such as antiseptics and pesticides. Volume V, however, deals with methylmercury except in cases where information on another organic is presented for illustrative purposes."
1238520,Garman et al. 1997,Developmental abnormalities and DNA-protein crosslinks in sea urchin embryos exposed to three metals,"Two sublethal responses were used to investigate the effects of genotoxic metals on embryos of the purple sea urchin, Strongylocentrotus purpuratus. In addition to the standard measurement of developmental success, we used a novel genotoxic response, DNA-protein crosslink (DPC) induction, to assess the effects of embryo exposure to pentavalent arsenate (As), nickel (Ni) and hexavalent chromate (Cr). The procedure for sea urchin embryo DPC measurement was adapted from a mammalian cell assay using potassium-SDS precipitation and a DNA fluorochrome to quantify relative amounts of free and protein-bound DNA. Developmental abnormality and DPCs increased after a 48-h exposure to each of the three metals. Lowest observable effect concentrations (LOECs) for development were 0.011 mg/L As, 0.40 mg/L Ni, and 2.5 mg/L Cr. LOECs calculated for the DPC response to these same three metals were 0.023, 8.0, and 10.0 mg/L, respectively. DPCs were transiently high in transcription of the embryonic genome. By the gastrula and prism stages (subsequent to embryo gene transcription), there was a significant decrease in DPCs. Ni-exposed embryos exhibited the greatest magnitude of adverse effect in embryos exposed through the blastula stage, as compared to those exposed from blastula through late gastrula stage. We hypothesize that stage-sensitivity to Ni in sea urchin embryos may be related to the induction of persistent DPCs, and the prevention of normal transcription of the embryonic genome.","Developmental abnormalities and DNA-protein crosslinks in sea urchin embryos exposed to three metals Abs: Two sublethal responses were used to investigate the effects of genotoxic metals on embryos of the purple sea urchin, Strongylocentrotus purpuratus. In addition to the standard measurement of developmental success, we used a novel genotoxic response, DNA-protein crosslink (DPC) induction, to assess the effects of embryo exposure to pentavalent arsenate (As), nickel (Ni) and hexavalent chromate (Cr). The procedure for sea urchin embryo DPC measurement was adapted from a mammalian cell assay using potassium-SDS precipitation and a DNA fluorochrome to quantify relative amounts of free and protein-bound DNA. Developmental abnormality and DPCs increased after a 48-h exposure to each of the three metals. Lowest observable effect concentrations (LOECs) for development were 0.011 mg/L As, 0.40 mg/L Ni, and 2.5 mg/L Cr. LOECs calculated for the DPC response to these same three metals were 0.023, 8.0, and 10.0 mg/L, respectively. DPCs were transiently high in transcription of the embryonic genome. By the gastrula and prism stages (subsequent to embryo gene transcription), there was a significant decrease in DPCs. Ni-exposed embryos exhibited the greatest magnitude of adverse effect in embryos exposed through the blastula stage, as compared to those exposed from blastula through late gastrula stage. We hypothesize that stage-sensitivity to Ni in sea urchin embryos may be related to the induction of persistent DPCs, and the prevention of normal transcription of the embryonic genome."
1238519,Gowrishankar et al. 1996,Foetotoxic effect of potassium chromate (K2CrO4) in Swiss albino mice,"The embryotoxic and teratogenic potential of potassium chromate was evaluated by the teratological analysis of mouse foetuses. The test chemical was administered intraperitoneally to laboratory-bred Swiss albino mice of both sexes for 30 days. Teratological scanning of the foetuses born to treated animals revealed a reduction in the number of live implants and litter size. Higher incidence of resorption and dead litter indicated the embryotoxic effect of the test chemical. Malformations, both skeletal and morphological, suggest the possibility of potassium chromate(K2CrO4) being foetotoxic.","Foetotoxic effect of potassium chromate (K2CrO4) in Swiss albino mice Abs: The embryotoxic and teratogenic potential of potassium chromate was evaluated by the teratological analysis of mouse foetuses. The test chemical was administered intraperitoneally to laboratory-bred Swiss albino mice of both sexes for 30 days. Teratological scanning of the foetuses born to treated animals revealed a reduction in the number of live implants and litter size. Higher incidence of resorption and dead litter indicated the embryotoxic effect of the test chemical. Malformations, both skeletal and morphological, suggest the possibility of potassium chromate(K2CrO4) being foetotoxic."
1238518,Little 1993,Are occupational carcinogens teratogenic?,"A variety of congenital anomalies have been associated with neoplasms in humans. In particular, acute lymphocytic leukaemia in childhood is associated with Bloom's syndrome, Fanconi's anaemia and Down's syndrome, lymphomas are associated with ataxia-telangiectasia, Wiskott-Aldrich syndrome and thymic alymphoplasia, and Wilms' tumor has been associated with a variety of congenital anomalies including aniridia, hemihypertrophy, and Beckwith-Wiedemann syndrome. These associations relate primarily to cancer in childhood and some have a clear genetic basis. However, carcinogens are inferred to interfere with cell function and such interference would be likely to affect developmental processes. Data on experimental carcinogenesis show that many agents known to be carcinogenic postnatally in animals are teratogenic to the fetus or embryo. For example, Di Paolo and Kotin listed 26 chemical agents that had been tested for both carcinogenic and teratogenic activity in animals. Of the 20 listed as carcinogenic, 19 had been shown to be teratogenic. Carcinogens have been identified from the IARC Monographs. Exposure to many of the carcinogens identified in the Monographs occurs in an occupational context and, therefore, the aim of this chapter is to assess the evidence as to the teratogenicity in humans of occupational exposures considered to be carcinogenic. First, the framework used to evaluate evidence as to the carcinogenicity of the occupational exposures will be described. Next, the sources of information on teratogenicity will be specified. Evidence regarding the teratogenicity of occupational exposures for which data are available on humans will then be considered. This will be followed by consideration of exposures for which data are available only from experimental animals. Finally, mechanisms whereby exposures may produce both teratogenic and carcinogenic affects will be discussed.","Are occupational carcinogens teratogenic? Abs: A variety of congenital anomalies have been associated with neoplasms in humans. In particular, acute lymphocytic leukaemia in childhood is associated with Bloom's syndrome, Fanconi's anaemia and Down's syndrome, lymphomas are associated with ataxia-telangiectasia, Wiskott-Aldrich syndrome and thymic alymphoplasia, and Wilms' tumor has been associated with a variety of congenital anomalies including aniridia, hemihypertrophy, and Beckwith-Wiedemann syndrome. These associations relate primarily to cancer in childhood and some have a clear genetic basis. However, carcinogens are inferred to interfere with cell function and such interference would be likely to affect developmental processes. Data on experimental carcinogenesis show that many agents known to be carcinogenic postnatally in animals are teratogenic to the fetus or embryo. For example, Di Paolo and Kotin listed 26 chemical agents that had been tested for both carcinogenic and teratogenic activity in animals. Of the 20 listed as carcinogenic, 19 had been shown to be teratogenic. Carcinogens have been identified from the IARC Monographs. Exposure to many of the carcinogens identified in the Monographs occurs in an occupational context and, therefore, the aim of this chapter is to assess the evidence as to the teratogenicity in humans of occupational exposures considered to be carcinogenic. First, the framework used to evaluate evidence as to the carcinogenicity of the occupational exposures will be described. Next, the sources of information on teratogenicity will be specified. Evidence regarding the teratogenicity of occupational exposures for which data are available on humans will then be considered. This will be followed by consideration of exposures for which data are available only from experimental animals. Finally, mechanisms whereby exposures may produce both teratogenic and carcinogenic affects will be discussed."
1238516,Stouthart et al. 1995,Effects of water pH on chromium toxicity to early life stages of the common carp (Cyprinus carpio),"Immediately after fertilization carp eggs were exposed to Cr(VI) concentrations of 3.9 and 9.6 umol/L at water pH 7.8 amd 6.3. At regular intervals mortality, the incidence of spinal cord deformation, heart rate, tail movements, hatching success, whole body concentration of K, Na, Mg, Ca, and Cr, and ultrastructure of skin and gills were assessed. No effects of Cr on any of the examined parameters were observed at pH 7.8, while 9.6 umol/L Cr at pH 6.3 decreased total Na concentration of larvae, and increased mortality of the larvae. Skin of larvae (144-h) exposed to 9.6 umol/L at pH 6.3 showed increased numbers of mucus-secreting cells. The gill epithelium had a wrinkled appearance, and dark circle-shaped spaces, probably of mucus cells, were seen. After 240 h, the larvae were almost completely covered with mucus. In controls at pH 6.3 no significant changes of any of the above parameters were observed when compared to controls at pH 7.8.","Effects of water pH on chromium toxicity to early life stages of the common carp (Cyprinus carpio) Abs: Immediately after fertilization carp eggs were exposed to Cr(VI) concentrations of 3.9 and 9.6 umol/L at water pH 7.8 amd 6.3. At regular intervals mortality, the incidence of spinal cord deformation, heart rate, tail movements, hatching success, whole body concentration of K, Na, Mg, Ca, and Cr, and ultrastructure of skin and gills were assessed. No effects of Cr on any of the examined parameters were observed at pH 7.8, while 9.6 umol/L Cr at pH 6.3 decreased total Na concentration of larvae, and increased mortality of the larvae. Skin of larvae (144-h) exposed to 9.6 umol/L at pH 6.3 showed increased numbers of mucus-secreting cells. The gill epithelium had a wrinkled appearance, and dark circle-shaped spaces, probably of mucus cells, were seen. After 240 h, the larvae were almost completely covered with mucus. In controls at pH 6.3 no significant changes of any of the above parameters were observed when compared to controls at pH 7.8."
1238514,Szakmäary et al. 1992,,"CFY rats were treated with tri- or hexavalent chromium salts during the whole time of gestation. It was found that the administered doses of trivalent chromium had neither maternal nor embryonal toxic effect. Hexavalent chromium proved to have specific embryotoxic and teratogenic effect in rats. Prenatal exposure decreased the vitality of the offsprings, but had no effect on the postnatal morpho-ontogenesis of the survivors."," Abs: CFY rats were treated with tri- or hexavalent chromium salts during the whole time of gestation. It was found that the administered doses of trivalent chromium had neither maternal nor embryonal toxic effect. Hexavalent chromium proved to have specific embryotoxic and teratogenic effect in rats. Prenatal exposure decreased the vitality of the offsprings, but had no effect on the postnatal morpho-ontogenesis of the survivors."
1238512,Ratnasooriya and  Balasuriya 1992,Antigestational effects of hexavalent chromium in the rat,Hexavalent chromium; sodium chromate; pregnancy; gestation; fertility,Antigestational effects of hexavalent chromium in the rat Abs: Hexavalent chromium; sodium chromate; pregnancy; gestation; fertility
1238509,group 1984,Health effects assessment for trivalent chromium,"In order to place the risk assessment evaluation in proper context, refer to the preface of this document. The preface outlines limitations applicable to all documents of this series as well as the appropriate interpretation and use of the quantitative estimates presented. Data are limited concerning the toxicological effects of trivalent chromium salts. Trivalent chromium appears to have a low order of toxicity, presumably due to very poor absorption, especially following oral exposure. Only one subchronic study adequate for risk assessment was located. Cr203 was administered in the diet of rats for 90 days at levels of 2% and 5%. The estimated daily consumption of Cr(+3) is 1373 mg/kg for the 5% feeding level. Based on this, an AIS of 979 mg/day was calculated. Adequate subchronic inhalation data were not located. Again, only one chronic feeding study was found, conducted by the same authors who reported the subchronic investigation. No adverse effects were seen at the highest feeding level, 5%. The daily intake at this level is estimated as 1467 mg Cr(+3)/kg. From these data, an AIC of 103 mg/day is estimated. Chronic inhalation data were not located. An AIC of 0.357 mg Cr(+3)/day is estimated based on the TLV. All of these estimates should be reviewed as more complete data become available. Data were not sufficient for derivation of a CS. Environmental chemistry and fate. The three most stable forms in which chromium occurs in the environment are 0 (metal and alloys), +3 and +6 valence states. In the +3 valence state, the chemistry of chromium is dominated by the formations of stable hexa- coordinated complexes with both organic and inorganic ligands. In the +6 valence state, chromium exists as oxo species such as CrO3 and CrO42'- that are strongly oxidizing. Chromium in the ambient air occurs from natural sources, industrial and product uses, and burning of fossil fuels and wood. The most important industrial sources of chromium in the atmospheric originate from ferrochrome production. Under normal conditions, Cr(+3) and Cr(0) in the air should not undergo any reaction. Cr(+6) in air could eventually react with dust particles or other pollutants to form Cr(+3); however, the exact nature of such atmospheric reactions has not been studied extensively. Chromium is removed from air by atmospheric fallout and precipitation. The atmospheric half-life for the physical removal mechanism is expected to depend on the particle size and particle density of atmospheric chromium. Chromium particles of small aerodynamic diameter (<10 um) may remain airborne for long periods of time and may be transported great distances by wind currents and diffusion forces. Surface runoff, deposition from air, and release of municipal and industrial waste waters are the sources of chromium in surface waters. The most significant removal mechanism for Cr(+3) from the aquatic environment will be precipitation as Cr2O3 x xH2O and eventually sedimentation of Cr2O3 x xH2O. Cr(+6), however, may exist in aquatic media as a water soluble complex anion and may persist in water for a long time. Cr(+6) is a moderately strong oxidizing agent and will react with organic matter or other reducing agents to form Cr(+3). Eventually, Cr(+3) will be precipitated as Cr2O3 x xH2O. Therefore, in surface water rich i organic content, Cr(+6) will exhibit a much shorter lifetime. Chromium probably occurs as the insoluble Cr2O3 x xH2O in soil, given that organic matter in soil is expected to convert any soluble chromate to insoluble Cr2O3. There is no known chemical process that can cause chromium to be lost from soil. The primary processes by which chromium is lost from soil are physical. For example, chromium in soil can be transported to the atmosphere by way of aerosol formation. Chromium is also transported from soil through runoff. Runoff can remove both chromium ions and bulk precipitates of chromium. In addition, flooding of soils and the subsequent anaerobic decomposition of plant matter may increase dissolution of Cr2O3 in soil through complexation. The wa er soluble complexes may cause leaching of chromium from soil. The BCF for Cr(06) in fish muscle appears to be <1.0, but values of 125 and 192 were obtained for oyster and blue mussel, respectively. For Cr(+3), BCF values of 116, 153 and 86 were obtained with the American oyster, soft shell clam and blue mussel.","Health effects assessment for trivalent chromium Abs: In order to place the risk assessment evaluation in proper context, refer to the preface of this document. The preface outlines limitations applicable to all documents of this series as well as the appropriate interpretation and use of the quantitative estimates presented. Data are limited concerning the toxicological effects of trivalent chromium salts. Trivalent chromium appears to have a low order of toxicity, presumably due to very poor absorption, especially following oral exposure. Only one subchronic study adequate for risk assessment was located. Cr203 was administered in the diet of rats for 90 days at levels of 2% and 5%. The estimated daily consumption of Cr(+3) is 1373 mg/kg for the 5% feeding level. Based on this, an AIS of 979 mg/day was calculated. Adequate subchronic inhalation data were not located. Again, only one chronic feeding study was found, conducted by the same authors who reported the subchronic investigation. No adverse effects were seen at the highest feeding level, 5%. The daily intake at this level is estimated as 1467 mg Cr(+3)/kg. From these data, an AIC of 103 mg/day is estimated. Chronic inhalation data were not located. An AIC of 0.357 mg Cr(+3)/day is estimated based on the TLV. All of these estimates should be reviewed as more complete data become available. Data were not sufficient for derivation of a CS. Environmental chemistry and fate. The three most stable forms in which chromium occurs in the environment are 0 (metal and alloys), +3 and +6 valence states. In the +3 valence state, the chemistry of chromium is dominated by the formations of stable hexa- coordinated complexes with both organic and inorganic ligands. In the +6 valence state, chromium exists as oxo species such as CrO3 and CrO42'- that are strongly oxidizing. Chromium in the ambient air occurs from natural sources, industrial and product uses, and burning of fossil fuels and wood. The most important industrial sources of chromium in the atmospheric originate from ferrochrome production. Under normal conditions, Cr(+3) and Cr(0) in the air should not undergo any reaction. Cr(+6) in air could eventually react with dust particles or other pollutants to form Cr(+3); however, the exact nature of such atmospheric reactions has not been studied extensively. Chromium is removed from air by atmospheric fallout and precipitation. The atmospheric half-life for the physical removal mechanism is expected to depend on the particle size and particle density of atmospheric chromium. Chromium particles of small aerodynamic diameter (<10 um) may remain airborne for long periods of time and may be transported great distances by wind currents and diffusion forces. Surface runoff, deposition from air, and release of municipal and industrial waste waters are the sources of chromium in surface waters. The most significant removal mechanism for Cr(+3) from the aquatic environment will be precipitation as Cr2O3 x xH2O and eventually sedimentation of Cr2O3 x xH2O. Cr(+6), however, may exist in aquatic media as a water soluble complex anion and may persist in water for a long time. Cr(+6) is a moderately strong oxidizing agent and will react with organic matter or other reducing agents to form Cr(+3). Eventually, Cr(+3) will be precipitated as Cr2O3 x xH2O. Therefore, in surface water rich i organic content, Cr(+6) will exhibit a much shorter lifetime. Chromium probably occurs as the insoluble Cr2O3 x xH2O in soil, given that organic matter in soil is expected to convert any soluble chromate to insoluble Cr2O3. There is no known chemical process that can cause chromium to be lost from soil. The primary processes by which chromium is lost from soil are physical. For example, chromium in soil can be transported to the atmosphere by way of aerosol formation. Chromium is also transported from soil through runoff. Runoff can remove both chromium ions and bulk precipitates of chromium. In addition, flooding of soils and the subsequent anaerobic decomposition of plant matter may increase dissolution of Cr2O3 in soil through complexation. The wa er soluble complexes may cause leaching of chromium from soil. The BCF for Cr(06) in fish muscle appears to be <1.0, but values of 125 and 192 were obtained for oyster and blue mussel, respectively. For Cr(+3), BCF values of 116, 153 and 86 were obtained with the American oyster, soft shell clam and blue mussel."
1238506,Anonymous 1993,Toxicological profile for lead,,Toxicological profile for lead Abs: 
1238505,Anonymous 1993,Chrom(VI)-Verbindungen (Addendum),MAK vgl. Abschn. III A 2; MAK-Werte-Liste 1993,Chrom(VI)-Verbindungen (Addendum) Abs: MAK vgl. Abschn. III A 2; MAK-Werte-Liste 1993
1238504,Anonymous 1991,Strontium chromate,"TLV-TWA, 0.0005 mg/m3, as Cr; A2-Suspected Human Carcinogen","Strontium chromate Abs: TLV-TWA, 0.0005 mg/m3, as Cr; A2-Suspected Human Carcinogen"
1238503,Fairhurst and  Minty 1989,The toxicity of chromium and inorganic chromium compounds,"The toxicity of metallic chromium in animals has been inadequately investigated. Very few studies have been conducted on chromium (II compounds; oral LD50 values of 791-3114 mg Cr(II)/kg have been reported for water-soluble chromium (II) compounds in rats. Water-soluble chromium (III), moderate toxicity. [LD50 values 140-422 mg Cr (III)/kg]. In general, negative genotoxicity results were obtained when chromium (III) compounds were tested in vitro for point mutations or DNA damage in bacteria, and for gene mutations, unscheduled DNA synthesis or cell transformation in mammalian cells, consistent with very poor cellular uptake of Cr (III). The results of in vitro tests for clastogenicity were somewhat more equivocal. The genotoxicity of chromium (III) compounds in vivo has been inadequately investigated, although negative results were obtained in the few studies available. Negative results have also been obtained in carcinogenicity studies in animals. Most studies used unrealistic methods of exposure. Effects of chromium (III) compounds on reproduction in animals have been poorly investigated. Intraperitoneal injection of chromium (III) chloride in mice produced embryo/fetolethality and teratogenicity, although it is not clear if such effects were seen only at maternally-toxic doses. Very little toxicological information was available on chromium (IV) compounds. In animals, highly water-soluble chromium (VI) compounds were very toxic by single inhalation exposure, producing damage to the respiratory tract. Cr (VI) induced skin sensitisation in guinea pigs. The Cr (VI) ion in solution gave positive results in a wide range of tests for genotoxicity in vitro. The results of animal carcinogenicity studies indicate that several chromium (VI) compounds of sparing to high water solubility were clearly carcinogenic in rats, producing lung tumours when administered via the respiratory tract (by inhalation, intratracheal instillation or intrabronchial implantation). The very poorly water-soluble chromium (VI) compounds gave equivocal or negative carcinogenic responses. Effects of chromium (VI) compounds on reproduction have been poorly investigated. Metallic chromium, binary chromium-non metal compounds, chromium hexacarbonyl. There was no evidence of adverse health effects in humans as a result of occupational exposure to these forms of chromium. There was no good evidence of adverse health effects in humans arising from occupational exposure to chromium (II) or chromium (III) compounds. There was almost no information available on the effects of chromium (IV) compounds in humans. Single inhalation or oral exposures of humans to highly water-soluble chromium (VI) compounds resulted in irritation and inflammation of the respiratory tract or corrosive burns to the gastrointestinal tract respectively. Repeated occupational exposure to airborne, highly water-soluble Cr (VI) in the chromate production and chromium plating industries has resulted in irritant and corrosive effects on the respiratory tract (nasal septum ulceration and perforation, inflammation of the entire length of the tract, fibrosis and emphysema) and gastrointestinal tract (inflammation and ulceration at various levels along the tract). Some evidence of kidney damage has also been found among workers in these industries. Workers exposed to chromium (VI) compounds of sparing to high water solubility, in chromate production, chromium plating and zinc chromate pigment manufacture, have shown a clear excess in mortality from lung cancer. This excess in lung cancer mortality cannot be related to particular atmospheric Cr (VI) levels in any reliable manner. Although there is some evidence that the incidence of lung cancer has declined among workers entering certain UK and USA chromate production and chromate pigment manufacturing plants in more recent times, it is not yet possible to deduce whether an increased risk of death from lung cancer persists in these industries. There is no good evidence that exposure to very poorly water-soluble chromium (VI) compounds has p oduced lung cancer in humans, although the evidence available in support of lack of human carcinogenicity for such compounds cannot be considered conclusive. Several investigations have been reported on chromosome damage in circulating lymphocytes from chromate production and chromium plating workers. The results of the better conducted and reported studies have been negative. There was no useful information available on the effects of chromium (VI) compounds on reproduction in humans. (Shortened)","The toxicity of chromium and inorganic chromium compounds Abs: The toxicity of metallic chromium in animals has been inadequately investigated. Very few studies have been conducted on chromium (II compounds; oral LD50 values of 791-3114 mg Cr(II)/kg have been reported for water-soluble chromium (II) compounds in rats. Water-soluble chromium (III), moderate toxicity. [LD50 values 140-422 mg Cr (III)/kg]. In general, negative genotoxicity results were obtained when chromium (III) compounds were tested in vitro for point mutations or DNA damage in bacteria, and for gene mutations, unscheduled DNA synthesis or cell transformation in mammalian cells, consistent with very poor cellular uptake of Cr (III). The results of in vitro tests for clastogenicity were somewhat more equivocal. The genotoxicity of chromium (III) compounds in vivo has been inadequately investigated, although negative results were obtained in the few studies available. Negative results have also been obtained in carcinogenicity studies in animals. Most studies used unrealistic methods of exposure. Effects of chromium (III) compounds on reproduction in animals have been poorly investigated. Intraperitoneal injection of chromium (III) chloride in mice produced embryo/fetolethality and teratogenicity, although it is not clear if such effects were seen only at maternally-toxic doses. Very little toxicological information was available on chromium (IV) compounds. In animals, highly water-soluble chromium (VI) compounds were very toxic by single inhalation exposure, producing damage to the respiratory tract. Cr (VI) induced skin sensitisation in guinea pigs. The Cr (VI) ion in solution gave positive results in a wide range of tests for genotoxicity in vitro. The results of animal carcinogenicity studies indicate that several chromium (VI) compounds of sparing to high water solubility were clearly carcinogenic in rats, producing lung tumours when administered via the respiratory tract (by inhalation, intratracheal instillation or intrabronchial implantation). The very poorly water-soluble chromium (VI) compounds gave equivocal or negative carcinogenic responses. Effects of chromium (VI) compounds on reproduction have been poorly investigated. Metallic chromium, binary chromium-non metal compounds, chromium hexacarbonyl. There was no evidence of adverse health effects in humans as a result of occupational exposure to these forms of chromium. There was no good evidence of adverse health effects in humans arising from occupational exposure to chromium (II) or chromium (III) compounds. There was almost no information available on the effects of chromium (IV) compounds in humans. Single inhalation or oral exposures of humans to highly water-soluble chromium (VI) compounds resulted in irritation and inflammation of the respiratory tract or corrosive burns to the gastrointestinal tract respectively. Repeated occupational exposure to airborne, highly water-soluble Cr (VI) in the chromate production and chromium plating industries has resulted in irritant and corrosive effects on the respiratory tract (nasal septum ulceration and perforation, inflammation of the entire length of the tract, fibrosis and emphysema) and gastrointestinal tract (inflammation and ulceration at various levels along the tract). Some evidence of kidney damage has also been found among workers in these industries. Workers exposed to chromium (VI) compounds of sparing to high water solubility, in chromate production, chromium plating and zinc chromate pigment manufacture, have shown a clear excess in mortality from lung cancer. This excess in lung cancer mortality cannot be related to particular atmospheric Cr (VI) levels in any reliable manner. Although there is some evidence that the incidence of lung cancer has declined among workers entering certain UK and USA chromate production and chromate pigment manufacturing plants in more recent times, it is not yet possible to deduce whether an increased risk of death from lung cancer persists in these industries. There is no good evidence that exposure to very poorly water-soluble chromium (VI) compounds has p oduced lung cancer in humans, although the evidence available in support of lack of human carcinogenicity for such compounds cannot be considered conclusive. Several investigations have been reported on chromosome damage in circulating lymphocytes from chromate production and chromium plating workers. The results of the better conducted and reported studies have been negative. There was no useful information available on the effects of chromium (VI) compounds on reproduction in humans. (Shortened)"
1238501,Anonymous 2001,Calcium Chromate,"A TLV-TWA of 0.001 mg/m3, measured as Cr, is recommended for occupational exposure to calcium chromate. This value is intended to minimize the potential for cancers of the respiratory tract and other sites reported for rats dosed intramuscularly, intrapleurally, intracheally, by intrabronchial implants, and by inhalation of calcium chromate. Such data warrant an A2, Suspected Human Carcinogen, notation. No epidemiological studies of workers exposed to calcium chromate were identified. Calcium chromate is considered to be approximately 10 times more potent a carcinogen than zinc chromate (TLV-TWA, 0.01 mg/m3) by intrabronchial implantation (see current TLV Documentation for Zinc Chromate). Sufficient data were not available to recommend Skin or SEN notations or a TLV-STEL.","Calcium Chromate Abs: A TLV-TWA of 0.001 mg/m3, measured as Cr, is recommended for occupational exposure to calcium chromate. This value is intended to minimize the potential for cancers of the respiratory tract and other sites reported for rats dosed intramuscularly, intrapleurally, intracheally, by intrabronchial implants, and by inhalation of calcium chromate. Such data warrant an A2, Suspected Human Carcinogen, notation. No epidemiological studies of workers exposed to calcium chromate were identified. Calcium chromate is considered to be approximately 10 times more potent a carcinogen than zinc chromate (TLV-TWA, 0.01 mg/m3) by intrabronchial implantation (see current TLV Documentation for Zinc Chromate). Sufficient data were not available to recommend Skin or SEN notations or a TLV-STEL."
1238500,Anonymous 2001,tert-Butyl Chromate,"A TLV-Ceiling of 0.1 mg/m3, measured as chromium trioxide is recommended for occupational exposure to tert-butyl chromate. This value is intended to minimize the potential for dermal and respiratory tract irritation. Data are extremely limited upon which to base an exposure value. A Skin notation is assigned, based on mortality reported for rats treated dermally with tert-butyl chromate. Sufficient data were not available to recommend SEN or carcinogenicity notations.","tert-Butyl Chromate Abs: A TLV-Ceiling of 0.1 mg/m3, measured as chromium trioxide is recommended for occupational exposure to tert-butyl chromate. This value is intended to minimize the potential for dermal and respiratory tract irritation. Data are extremely limited upon which to base an exposure value. A Skin notation is assigned, based on mortality reported for rats treated dermally with tert-butyl chromate. Sufficient data were not available to recommend SEN or carcinogenicity notations."
1238498,Anonymous 2000,Toxicological profile for Chromium,,Toxicological profile for Chromium Abs: 
1238497,standards 1995,Scientific documentation on the dutch list of occupational carcinogens (1). Chromium trioxide,"There is inadequate evidence that exposure to chromoiumtrioxide alone is carcinogenic to human and experimental animals. Soluble (Cr(VI) is mutagenic in prokaryotic, fungi, mammals in vitro and in vivo, and human in vivo; but specific data on CrO3 are very limited. Chromiumtrioxide is considered as genotoxic carcinogen.","Scientific documentation on the dutch list of occupational carcinogens (1). Chromium trioxide Abs: There is inadequate evidence that exposure to chromoiumtrioxide alone is carcinogenic to human and experimental animals. Soluble (Cr(VI) is mutagenic in prokaryotic, fungi, mammals in vitro and in vivo, and human in vivo; but specific data on CrO3 are very limited. Chromiumtrioxide is considered as genotoxic carcinogen."
1238496,standards 1994,Scientific basis for Swedish occupational standards. XV. Consensus report for Strontium and Strontium compounds,"Dose-response/ dose-effect relationships. Human data: Extremely high chromate concentrations in blood (387 to 4160 nmol/l) and urine (99 to 444 nmol/mmol creatine) were measured in workers exposed to strontium chromate during manufacture of chromate pigment. Physical examinations of the 13 exposed subject revealed that 11 had inflammation in nasal mucosa, 7 had skin eruptions and 1 had erosion of the nasal septum. Similar effects have been observed with exposure to other chromium compounds. Animal data: For strontium, the LD50 for intraperitoneal injection to animals is 90 to 259 mg/kg body weight. For strontium chromate, the LD50 for rats is 3118 mg/kg with oral administration and 16,600 mg/kg for intravenous injection. For strontium chloride, the lethal intravenous dose is 123 mg/kg for rats and 590 mg/kg for rabbits. Rats given SrCl2x6H2O in food showed no effects on behaviour, appetite or growth at any of the tested dose levels. In the highest exposure groups, a dose-dependent activation and enlargement of the thyroid was seen in males and increased glycogen depletion was noted in the livers of the females. Conclusions. Judging mostly from animal data, the critical effects of exposure to strontium and its compounds are effects on the muscles and inhibited mineralization of bone tissue.","Scientific basis for Swedish occupational standards. XV. Consensus report for Strontium and Strontium compounds Abs: Dose-response/ dose-effect relationships. Human data: Extremely high chromate concentrations in blood (387 to 4160 nmol/l) and urine (99 to 444 nmol/mmol creatine) were measured in workers exposed to strontium chromate during manufacture of chromate pigment. Physical examinations of the 13 exposed subject revealed that 11 had inflammation in nasal mucosa, 7 had skin eruptions and 1 had erosion of the nasal septum. Similar effects have been observed with exposure to other chromium compounds. Animal data: For strontium, the LD50 for intraperitoneal injection to animals is 90 to 259 mg/kg body weight. For strontium chromate, the LD50 for rats is 3118 mg/kg with oral administration and 16,600 mg/kg for intravenous injection. For strontium chloride, the lethal intravenous dose is 123 mg/kg for rats and 590 mg/kg for rabbits. Rats given SrCl2x6H2O in food showed no effects on behaviour, appetite or growth at any of the tested dose levels. In the highest exposure groups, a dose-dependent activation and enlargement of the thyroid was seen in males and increased glycogen depletion was noted in the livers of the females. Conclusions. Judging mostly from animal data, the critical effects of exposure to strontium and its compounds are effects on the muscles and inhibited mineralization of bone tissue."
1238495,Anonymous 1989,Zinc Chromate,"There are no inhalation studies in animals to assess the carcinogenicity of zinc chromate by this route, which is the main route of human exposure. After other routes of exposure (intrapleural, intrabronchial, intramuscular) in rats, various forms of zinc chromate produce malignant or unspecified tumours at the site of application. Zinc chromate is mutagenic to bacteria. In cultured mammalian cells it is DNA damaging, mutagenic, clastogenic and it increases the frequencies of sister chromatid exchanges and induces cell transformations. Epidemiological studies show that exposure of workers to zinc chromate, mainly by inhalation, induces lung cancer.","Zinc Chromate Abs: There are no inhalation studies in animals to assess the carcinogenicity of zinc chromate by this route, which is the main route of human exposure. After other routes of exposure (intrapleural, intrabronchial, intramuscular) in rats, various forms of zinc chromate produce malignant or unspecified tumours at the site of application. Zinc chromate is mutagenic to bacteria. In cultured mammalian cells it is DNA damaging, mutagenic, clastogenic and it increases the frequencies of sister chromatid exchanges and induces cell transformations. Epidemiological studies show that exposure of workers to zinc chromate, mainly by inhalation, induces lung cancer."
1238494,Anonymous 1989,Strontium chromate,"There are no inhalation studies in animals to assess the carcinogenicity of strontium chromate by this route which is the main route of humans exposure. After other routes of exposure (intrabronchial, intrapleural and intramuscular implantation) in rats strontium chromate produced malignant lung tumours and tumours at the site of implantation. Strontium chromate is mutagenic to bacteria. Studies are not available on workers exposed only to strontium chromate. An excess risk of lung cancer has been observed in workers producing mainly zinc and lead chromates.","Strontium chromate Abs: There are no inhalation studies in animals to assess the carcinogenicity of strontium chromate by this route which is the main route of humans exposure. After other routes of exposure (intrabronchial, intrapleural and intramuscular implantation) in rats strontium chromate produced malignant lung tumours and tumours at the site of implantation. Strontium chromate is mutagenic to bacteria. Studies are not available on workers exposed only to strontium chromate. An excess risk of lung cancer has been observed in workers producing mainly zinc and lead chromates."
1238493,Anonymous 1989,Lead chromate,"There are no inhalation studies in animals to assess the carcinogenicity of lead chromate by this route which is the main route of human exposure. After other routes of exposure (intrabronchial implantation) lead chromate from different sources did not induce a significant number of lung carcinomas in rats. Less relevant for the evaluation of the carcinogenicity of lead chromate, was the finding that its intramuscular and subcutaneous injection produced malignant tumours at the site of injection and some renal carcinomas in the intramusculartreated group. Lead chromate is mutagenic to bacteria. In cultured mammalian cells it failed to induce mutations, but it is clastogenic, and it increases sister chromatid exchanges and cell transformations. Epidemiological data clearly indicate an increase in lung cancer mainly by inhalation in the case of mixed zinc and lead chromate exposure. At present no data are available to evaluate the carcinogenicity to humans of exposure to lead chromate per se.","Lead chromate Abs: There are no inhalation studies in animals to assess the carcinogenicity of lead chromate by this route which is the main route of human exposure. After other routes of exposure (intrabronchial implantation) lead chromate from different sources did not induce a significant number of lung carcinomas in rats. Less relevant for the evaluation of the carcinogenicity of lead chromate, was the finding that its intramuscular and subcutaneous injection produced malignant tumours at the site of injection and some renal carcinomas in the intramusculartreated group. Lead chromate is mutagenic to bacteria. In cultured mammalian cells it failed to induce mutations, but it is clastogenic, and it increases sister chromatid exchanges and cell transformations. Epidemiological data clearly indicate an increase in lung cancer mainly by inhalation in the case of mixed zinc and lead chromate exposure. At present no data are available to evaluate the carcinogenicity to humans of exposure to lead chromate per se."
1238492,Anonymous 1989,Calcium chromate,"There are no adequate inhalation studies in animals to assess the carcinogenicity of calcium chromate by this route which is the main route of human exposure. After other routes of exposure (intrabronchial, intratracheal, intrapleural, intramuscular or subcutaneous) in mice and rats calcium chromate produces tumours at the sites of application. Calcium chromate is DNA damaging and mutagenic to bacteria. In cultured cell assay systems it induces sister chromatid exchanges and cell transformations. There are not epidemiological data available to assess the carcinogenicity of calcium chromate per se to humans. An excess risk of lung cancer has been observed in workers producing mainly zinc and lead chromate.","Calcium chromate Abs: There are no adequate inhalation studies in animals to assess the carcinogenicity of calcium chromate by this route which is the main route of human exposure. After other routes of exposure (intrabronchial, intratracheal, intrapleural, intramuscular or subcutaneous) in mice and rats calcium chromate produces tumours at the sites of application. Calcium chromate is DNA damaging and mutagenic to bacteria. In cultured cell assay systems it induces sister chromatid exchanges and cell transformations. There are not epidemiological data available to assess the carcinogenicity of calcium chromate per se to humans. An excess risk of lung cancer has been observed in workers producing mainly zinc and lead chromate."
1238491,Anonymous 1987,"Chromium and chromium compounds: chromium metal (Group 3), trivalent chromium compounds (Group 3), hexavalent chromium compounds (Group 1)","A. Evidence for carcinogenicity to humans (inadequate for chromium metal and trivalent chromium compounds; sufficient for hexavalent chromium compounds) An increased incidence of lung cancer has been observed among workers in both the bichromate-producing industry and chromate-pigment manufacturing. There is evidence of a similar risk among chromium platers and chromium alloy workers. The incidences of cancers at other sites may also be increased in such populations. However, a clear distinction between the relative carcinogenicity of chromium compounds of different oxidation states or solubilities has been difficult to achieve. Recent studies of chromate-pigment makers and users, chrome platers, welders and chrome-alloy foundry workers have shed some light on this problem. For chromatepigment makers and users, respiratory cancer excesses have usually been found. Chromium pigments are usually hexavalent and commonly include zinc, lead or strontium chromate. A small Norwegian study identified 24 workers primarily exposed to zinc chromate out of a total chromium-pigment worker population of 133. All six lung cancer cases, with more than three years' exposure, occurred among the zinc chromate group (0.14 expected). One report from the UK contrasts the mortality experience of three plants, in one of which only lead chromate was used. The lung cancer excess was restricted to the plants in which there was mixed exposure to lead and zinc chromate. In the lead chromate plant, there was no lung cancer excess, whereas in the other two the observed:expected ratios for high-/medium-exposed workers ranged from 13:5.9 to 5:0.9. Chrome platers have also been found to have excess lung cancer. Stainless-steel welding involves the greatest exposure to hexavalent chromium, as well as to nickel, and observed:expected ratios for lung cancer for this subgroup of welders ranged from 4.4 (based on three cases) to 1.7 (based on six cases). One study of chromium-nickel alloy foundry workers showed a statistically significant excess of lung cancer in the 65-99-year age group only. Excess ratios for tumours at other sites are an unusual finding, but they have been reported for chromate paint workers (gastrointestinal tract), chromate-pigment users (stomach and pancreas) and chrome platers (gastrointestinal tract). The observed numbers are, however, small, and the observed:expected ratios do not reach statistical significance. In a post-mortem investigation of lung cancer deaths, it was found that, of the cases diagnosed as small-cell carcinoma, many had been exposed mainly to hexavalent chromium compounds. B. Evidence for carcinogenicity to animals (inadequate for chromium metal and trivalent chromium compounds; sufficient for hexavalent chromium compounds) Chromium metal and chromium compounds have been tested for carcinogenicity by a wide variety of routes in mice, rats and rabbits. Calcium chromate produced bronchial carcinomas after implantation of an intrabronchial pellet in rats and injection-site sarcomas after intramuscular implantation in rats and mice and after intrapleural injection in rats. Bronchial carcinomas were produced in rats after intrabronchial implantation of strontium chromate and zinc chromate. Injection-site sarcomas were produced in rats and in mice after intramuscular, intrapleural and subcutaneous injections of chromite ore, strontium chromate, chromium trioxide, lead chromate and zinc chromate, but few or no sarcomas were induced by barium chromate, sodium chromate or dichromate, or chromic acetate. Chromium powder has been tested inadequately in mice, rats and rabbits. C. Other relevant data The available evidence indicates that the carcinogenicity of chromium-containing materials can be related to both valency and bioavailability. Trivalent and hexavalent chromium have markedly different chemical and biological properties. Trivalent chromium is the more stable oxidation state, and under physiological conditions it may form complexes with ligands such as nucleic acids, proteins and organic acids. Biological membr nes are thought to be impermeable to trivalent chromium, although phagocytosis of particulate trivalent chromium can occur. Hexavalent chromium usually forms strongly oxidizing chromate and dichromate ions, which readily cross biological membranes and are easily reduced under physiological conditions to trivalent chromium. Trivalent chromium compounds may be contaminated with hexavalent chromium compounds (and vice versa). Chromium compounds that are sparingly soluble in water appear to have greater carcinogenic activity than those substances that are either highly soluble or insoluble. People occupationally exposed to hexavalent chromium compounds (in chromate production and in electroplating factories) had elevated incidences of chromosomal aberrations in their peripheral blood lymphocytes; reports on sister chromatid exchange induction were conflicting. Workers exposed to chromium compounds during stainless-steel welding did not show increased incidences of chromosomal aberrations, micronuclei or sister chromatid exchanges in peripheral blood lymphocytes. No data were available on the genetic and related effects of trivalent chromium compounds in humans. Hexavalent chromium induced dominant lethal mutations, chromosomal aberrations and micronuclei in rodents treated in vivo. In human cells in vitro, it caused chromosomal aberrations, sister chromatid exchanges and DNA damage. In cultured rodent cells, it induced transformation, chromosomal aberrations, sister chromatid exchanges, mutation and DNA damage. It induced aneuploidy in Drosophila and mitotic recombination in yeast. It was mutagenic and caused DNA damage in bacteria. There is no consistent evidence that water-soluble trivalent chromium has genetic activity. The few positive results were obtained only with doses about 100 times higher than those of hexavalent chromium required to produce such effects. Trivalent chromium did not induce micronuclei in bone-marrow cells of mice treated in vivo. Conflicting results were obtained for the induction of chromosomal aberrations in human lymphocytes in vitro, and neither sister chromatid exchange nor unscheduled DNA synthesis was induced in human cells in vitro. Conflicting results were obtained concerning the induction of chromosomal aberrations, mutation and sister chromatid exchanges in rodent cells in culture. Trivalent chromium did not induce mutation in bacteria, but it induced DNA damage. Insoluble crystalline chromium oxide (Cr2O3) induced sister chromatid exchanges and mutation in cultured Chinese hamster cells, which were shown to contain particles of the test material.","Chromium and chromium compounds: chromium metal (Group 3), trivalent chromium compounds (Group 3), hexavalent chromium compounds (Group 1) Abs: A. Evidence for carcinogenicity to humans (inadequate for chromium metal and trivalent chromium compounds; sufficient for hexavalent chromium compounds) An increased incidence of lung cancer has been observed among workers in both the bichromate-producing industry and chromate-pigment manufacturing. There is evidence of a similar risk among chromium platers and chromium alloy workers. The incidences of cancers at other sites may also be increased in such populations. However, a clear distinction between the relative carcinogenicity of chromium compounds of different oxidation states or solubilities has been difficult to achieve. Recent studies of chromate-pigment makers and users, chrome platers, welders and chrome-alloy foundry workers have shed some light on this problem. For chromatepigment makers and users, respiratory cancer excesses have usually been found. Chromium pigments are usually hexavalent and commonly include zinc, lead or strontium chromate. A small Norwegian study identified 24 workers primarily exposed to zinc chromate out of a total chromium-pigment worker population of 133. All six lung cancer cases, with more than three years' exposure, occurred among the zinc chromate group (0.14 expected). One report from the UK contrasts the mortality experience of three plants, in one of which only lead chromate was used. The lung cancer excess was restricted to the plants in which there was mixed exposure to lead and zinc chromate. In the lead chromate plant, there was no lung cancer excess, whereas in the other two the observed:expected ratios for high-/medium-exposed workers ranged from 13:5.9 to 5:0.9. Chrome platers have also been found to have excess lung cancer. Stainless-steel welding involves the greatest exposure to hexavalent chromium, as well as to nickel, and observed:expected ratios for lung cancer for this subgroup of welders ranged from 4.4 (based on three cases) to 1.7 (based on six cases). One study of chromium-nickel alloy foundry workers showed a statistically significant excess of lung cancer in the 65-99-year age group only. Excess ratios for tumours at other sites are an unusual finding, but they have been reported for chromate paint workers (gastrointestinal tract), chromate-pigment users (stomach and pancreas) and chrome platers (gastrointestinal tract). The observed numbers are, however, small, and the observed:expected ratios do not reach statistical significance. In a post-mortem investigation of lung cancer deaths, it was found that, of the cases diagnosed as small-cell carcinoma, many had been exposed mainly to hexavalent chromium compounds. B. Evidence for carcinogenicity to animals (inadequate for chromium metal and trivalent chromium compounds; sufficient for hexavalent chromium compounds) Chromium metal and chromium compounds have been tested for carcinogenicity by a wide variety of routes in mice, rats and rabbits. Calcium chromate produced bronchial carcinomas after implantation of an intrabronchial pellet in rats and injection-site sarcomas after intramuscular implantation in rats and mice and after intrapleural injection in rats. Bronchial carcinomas were produced in rats after intrabronchial implantation of strontium chromate and zinc chromate. Injection-site sarcomas were produced in rats and in mice after intramuscular, intrapleural and subcutaneous injections of chromite ore, strontium chromate, chromium trioxide, lead chromate and zinc chromate, but few or no sarcomas were induced by barium chromate, sodium chromate or dichromate, or chromic acetate. Chromium powder has been tested inadequately in mice, rats and rabbits. C. Other relevant data The available evidence indicates that the carcinogenicity of chromium-containing materials can be related to both valency and bioavailability. Trivalent and hexavalent chromium have markedly different chemical and biological properties. Trivalent chromium is the more stable oxidation state, and under physiological conditions it may form complexes with ligands such as nucleic acids, proteins and organic acids. Biological membr nes are thought to be impermeable to trivalent chromium, although phagocytosis of particulate trivalent chromium can occur. Hexavalent chromium usually forms strongly oxidizing chromate and dichromate ions, which readily cross biological membranes and are easily reduced under physiological conditions to trivalent chromium. Trivalent chromium compounds may be contaminated with hexavalent chromium compounds (and vice versa). Chromium compounds that are sparingly soluble in water appear to have greater carcinogenic activity than those substances that are either highly soluble or insoluble. People occupationally exposed to hexavalent chromium compounds (in chromate production and in electroplating factories) had elevated incidences of chromosomal aberrations in their peripheral blood lymphocytes; reports on sister chromatid exchange induction were conflicting. Workers exposed to chromium compounds during stainless-steel welding did not show increased incidences of chromosomal aberrations, micronuclei or sister chromatid exchanges in peripheral blood lymphocytes. No data were available on the genetic and related effects of trivalent chromium compounds in humans. Hexavalent chromium induced dominant lethal mutations, chromosomal aberrations and micronuclei in rodents treated in vivo. In human cells in vitro, it caused chromosomal aberrations, sister chromatid exchanges and DNA damage. In cultured rodent cells, it induced transformation, chromosomal aberrations, sister chromatid exchanges, mutation and DNA damage. It induced aneuploidy in Drosophila and mitotic recombination in yeast. It was mutagenic and caused DNA damage in bacteria. There is no consistent evidence that water-soluble trivalent chromium has genetic activity. The few positive results were obtained only with doses about 100 times higher than those of hexavalent chromium required to produce such effects. Trivalent chromium did not induce micronuclei in bone-marrow cells of mice treated in vivo. Conflicting results were obtained for the induction of chromosomal aberrations in human lymphocytes in vitro, and neither sister chromatid exchange nor unscheduled DNA synthesis was induced in human cells in vitro. Conflicting results were obtained concerning the induction of chromosomal aberrations, mutation and sister chromatid exchanges in rodent cells in culture. Trivalent chromium did not induce mutation in bacteria, but it induced DNA damage. Insoluble crystalline chromium oxide (Cr2O3) induced sister chromatid exchanges and mutation in cultured Chinese hamster cells, which were shown to contain particles of the test material."
1238490,Janus and  Krajnc 1990,Integrated criteria document chromium: effects,"Human Toxicity: Cr(III) - being present in biological material as an organic compound, the so-called ""glucose tolerance factor"" - is an essential trace element for mammals. It is estimated that the minimal requirement for adults is provided by a daily dietary intake of 2 to 8 ug Cr(III), corresponding with 0.03 to 0.13 ug Cr(III).kg bw.day-1. There is conclusive evidence that Cr(VI) is carcinogenic to mammals, including man. Because of the mutagenic activity, Cr(VI) is considered to be a genotoxic carcinogen. Therefore, a dose-without-effect with regard to carcinogenicity can not be established. After parenteral administration of either Cr(VI) or Cr(III) to pregnant hamsters and mice in specific teratogenicity studies, developmental effects (including malformations) have been reported. However, developmental toxicity tests in which animals were exposed orally or by inhalation are very limited and, therefore, do not allow an evaluation of the risk to humans which are exposed only orally or by inhalation. The oral studies available with regard to Cr(III) are considered to be too limited to establish an acceptable daily intake. Based on feeding studies with insoluble chromic oxide pigment (Cr2O3), a dose-without-effect (DWE) of 1,210 mg Cr(III).kg-1 bw.day-1 was established; assuming a fractional absorption of 0.5%, this DWE corresponds with 6 mg absorbed-Cr(III).kg-1 bw.day-1. Based on a study in which animals were exposed to relatively soluble chromic chloride (CrCl3) in drinking water, a DWE of 2.5 mg Cr(III).kg-1 bw.day-1 was established; assuming a fractional absorption of 5%, this DWE corresponds with 0.125 mg absorbed-Cr(III).kg-1 bw.day-1. Data on the daily dietary intake of chromium in The Netherlands are not available. Based on foreign data (""total diet studies"") summarized in the Criteria Document, the average daily dietary intake is estimated to be 100 ug total-Cr.day-1, with a range of 50 to 200 ug total-Cr.day-1. Data on the speciation of chromium in the diet are not available. Based on the speciation of chromium in biological material [organic Cr(III)] and the small contribution of drinking water [containing 0.1-0.8 ug total-Cr.l-1 in The Netherlands] to the chromium level in the total diet, it is assumed that by far most chromium in the diet is present as Cr(III). Therefore, the upper limit of 200 ug total-Cr.day-1 is corresponding with 0.83 ug absorbed-Cr(III).kg-1 bw.day-1 (based on a fractional absorption of 25% and a body weight of 60 kg). The two above-mentioned DWE-values (125 and 6,000 ug absorbed-Cr(III).kg-1 bw.day-1, respectively) based on long-term animal experiments are 150 times and 7000 times, respectively, higher than the upper limit of human intake (0.83 ug absorbed-Cr(III).kg-1 bw.day-1). Based on these ""margins of safety"" adverse effects are not expected to occur at the current exposure levels. Because of data on the speciation of chromium in surface water in The Netherlands, it must be noticed that it can not be excluded that chromium in drinking water may be present partially as Cr(VI). If so, Cr(VI) will be converted partially to Cr(III) due to intragastric reduction; quantitative data on this reduction are not available. The available studies in which animals were orally exposed to Cr(VI) are too limited for a risk assessment for man. Because Cr(VI) is considered to be a genotoxic carcinogen, exposure to Cr(VI) should be as low as possible. Exposure to Cr(III) by inhalation results in a daily intake which is less than 0.1% of the dietary intake, assuming an airborne concentration of 5 ng.m-3 and a respiration volume of 12 m3 per day. Because exposure to Cr(III) by inhalation is not expected to result in different effects than oral exposure, exposure to Cr(III) by inhalation is considered relevant. Therefore, this risk assessment is limited to Cr(VI). Although there appear to be differences in the carcinogenic potency of different Cr(VI) compounds, it is not possible to quantify these differences. Moreover, data on the speciation of Cr(VI) in air are not available. The ""unit risk"" f 40 x 10E-3, calculated by the World Health Organization (WHO, 1987), is considered to be the best estimate of the carcinogenic potency of Cr(VI). The ""unit risk"" is defined as ""the additional lifetime cancer risk occurring in a hypothetical population in which all individuals are exposed continuously from birth throughout their lifetimes to a concentration of 1 ug.m-3 of the agent in the air they breathe"". Assuming an acceptable risk of 1 x 10E-6 (one extra case of lung cancer per million persons exposed lifetime), this risk corresponds with an airborne concentration of 25 x 10E-6 ug Cr(VI).m-3 [0.025 ng Cr(VI).m-3]. Aquatic organisms: Accumulation and food chain transfer: Chromium is accumulated to a limited extend by aquatic animals. The concentrations in aquatic organisms decrease with increasing trophic level. In general, concentrations up to 10 and 5 mg.kg- 1 fresh weight have been reported in invertebrates and vertebrates (fish), respectively. These concentrations are based on both freshwater and seawater organisms. Based on these data it is concluded that biomagnification (the occurrence of a substance at successive higher concentrations with increasing trophic levels in food chains) of chromium is of no-account. Toxicity to freshwater organisms: Short-term ""single species"" tests with most species of invertebrates have resulted in L(E)C50-values of 2,000 to 60,000 ug.l-1, based on tests with both Cr(III) and Cr(VI). Crustaceans, especially cladocerans (Daphnia sp.) are more sensitive, with L(E)C50-values of 10 to 500 ug.l-1. In general, fish are less sensitive than invertebrates: LC50-values for fish are 3,000 to 190,000 ug.l-1. The toxicity of Cr(VI) increases with decreasing pH and hardness of the water. Long-term ""single species"" tests with Cr(VI) have resulted in NOEC-values of 0.35 to 6,650 ug.l- 1. Relatively low values have been reported for organisms of different, important taxonomic groups, namely algae, crustaceans and fish. In general, fish are less sensitive than invertebrates. Long-term tests with Cr(III) have resulted in NOEC-values of 48 to 330 ug.l-l. In experimental micro-ecosystems (algae) a concentration of 100 ug Cr(VI).l-1 has resulted in a reduction of diatom abundance and diversity. Toxicity to marine organisms: Short-term ""single species"" tests with Cr(VI) have resulted in L(E)C50-values of 2,000 to 105,000 ug Cr(VI).l-1; these values are based on tests with both invertebrates and vertebrates. The lowest values have been reported for crustaceans and polychaete worms. L(E)C50-values based on tests with Cr(III) are 10,000 to 56,000 ug Cr(III).l-1. Long-term ""single species"" tests with Cr(VI) have resulted in NOEC-values of 13 to 770 ug Cr(VI).l-1. The only available NOEC resulting from a test with Cr(III) is 50,400 ug Cr(III).l-1; in this test only 20 ug Cr(III).l-1 was found to be dissolved (0.1 um). Based on these NOEC-values and additional data it is concluded that Cr(III) is less toxic than Cr(VI) in sea water. Terrestrial organisms: Toxicity: In some short-term experiments effects on microbes (numbers, diversity) and microbe-mediated processes (respiration, ammonification, nitrification, enzym-activities) have been reported at concentrations of 25 to 100 mg.kg-1 dry weight [Cr(III) or ""chromium""] and 1 to 10 mg Cr(VI).kg-1. However, in most short-term experiments and in long-term experiments no effects have been reported at concentrations up to 200 mg.kg-1 (dry weight) [Cr(III) or ""chromium""]. In a test with the earthworm Eisenia Andrei, a concentration of 1,000 mg Cr(III).kg-1 dry weight resulted in adverse effects on growth and reproduction. The resulting NOEC is 300 mg Cr(III).kg- 1 dry weight. In two tests in which other earthworm species were exposed to Cr(VI), concentrations of 2 and 10 mg Cr(VI).kg-1, respectively, resulted in increased mortality. Relevant data on other terrestrial organisms are not available.","Integrated criteria document chromium: effects Abs: Human Toxicity: Cr(III) - being present in biological material as an organic compound, the so-called ""glucose tolerance factor"" - is an essential trace element for mammals. It is estimated that the minimal requirement for adults is provided by a daily dietary intake of 2 to 8 ug Cr(III), corresponding with 0.03 to 0.13 ug Cr(III).kg bw.day-1. There is conclusive evidence that Cr(VI) is carcinogenic to mammals, including man. Because of the mutagenic activity, Cr(VI) is considered to be a genotoxic carcinogen. Therefore, a dose-without-effect with regard to carcinogenicity can not be established. After parenteral administration of either Cr(VI) or Cr(III) to pregnant hamsters and mice in specific teratogenicity studies, developmental effects (including malformations) have been reported. However, developmental toxicity tests in which animals were exposed orally or by inhalation are very limited and, therefore, do not allow an evaluation of the risk to humans which are exposed only orally or by inhalation. The oral studies available with regard to Cr(III) are considered to be too limited to establish an acceptable daily intake. Based on feeding studies with insoluble chromic oxide pigment (Cr2O3), a dose-without-effect (DWE) of 1,210 mg Cr(III).kg-1 bw.day-1 was established; assuming a fractional absorption of 0.5%, this DWE corresponds with 6 mg absorbed-Cr(III).kg-1 bw.day-1. Based on a study in which animals were exposed to relatively soluble chromic chloride (CrCl3) in drinking water, a DWE of 2.5 mg Cr(III).kg-1 bw.day-1 was established; assuming a fractional absorption of 5%, this DWE corresponds with 0.125 mg absorbed-Cr(III).kg-1 bw.day-1. Data on the daily dietary intake of chromium in The Netherlands are not available. Based on foreign data (""total diet studies"") summarized in the Criteria Document, the average daily dietary intake is estimated to be 100 ug total-Cr.day-1, with a range of 50 to 200 ug total-Cr.day-1. Data on the speciation of chromium in the diet are not available. Based on the speciation of chromium in biological material [organic Cr(III)] and the small contribution of drinking water [containing 0.1-0.8 ug total-Cr.l-1 in The Netherlands] to the chromium level in the total diet, it is assumed that by far most chromium in the diet is present as Cr(III). Therefore, the upper limit of 200 ug total-Cr.day-1 is corresponding with 0.83 ug absorbed-Cr(III).kg-1 bw.day-1 (based on a fractional absorption of 25% and a body weight of 60 kg). The two above-mentioned DWE-values (125 and 6,000 ug absorbed-Cr(III).kg-1 bw.day-1, respectively) based on long-term animal experiments are 150 times and 7000 times, respectively, higher than the upper limit of human intake (0.83 ug absorbed-Cr(III).kg-1 bw.day-1). Based on these ""margins of safety"" adverse effects are not expected to occur at the current exposure levels. Because of data on the speciation of chromium in surface water in The Netherlands, it must be noticed that it can not be excluded that chromium in drinking water may be present partially as Cr(VI). If so, Cr(VI) will be converted partially to Cr(III) due to intragastric reduction; quantitative data on this reduction are not available. The available studies in which animals were orally exposed to Cr(VI) are too limited for a risk assessment for man. Because Cr(VI) is considered to be a genotoxic carcinogen, exposure to Cr(VI) should be as low as possible. Exposure to Cr(III) by inhalation results in a daily intake which is less than 0.1% of the dietary intake, assuming an airborne concentration of 5 ng.m-3 and a respiration volume of 12 m3 per day. Because exposure to Cr(III) by inhalation is not expected to result in different effects than oral exposure, exposure to Cr(III) by inhalation is considered relevant. Therefore, this risk assessment is limited to Cr(VI). Although there appear to be differences in the carcinogenic potency of different Cr(VI) compounds, it is not possible to quantify these differences. Moreover, data on the speciation of Cr(VI) in air are not available. The ""unit risk"" f 40 x 10E-3, calculated by the World Health Organization (WHO, 1987), is considered to be the best estimate of the carcinogenic potency of Cr(VI). The ""unit risk"" is defined as ""the additional lifetime cancer risk occurring in a hypothetical population in which all individuals are exposed continuously from birth throughout their lifetimes to a concentration of 1 ug.m-3 of the agent in the air they breathe"". Assuming an acceptable risk of 1 x 10E-6 (one extra case of lung cancer per million persons exposed lifetime), this risk corresponds with an airborne concentration of 25 x 10E-6 ug Cr(VI).m-3 [0.025 ng Cr(VI).m-3]. Aquatic organisms: Accumulation and food chain transfer: Chromium is accumulated to a limited extend by aquatic animals. The concentrations in aquatic organisms decrease with increasing trophic level. In general, concentrations up to 10 and 5 mg.kg- 1 fresh weight have been reported in invertebrates and vertebrates (fish), respectively. These concentrations are based on both freshwater and seawater organisms. Based on these data it is concluded that biomagnification (the occurrence of a substance at successive higher concentrations with increasing trophic levels in food chains) of chromium is of no-account. Toxicity to freshwater organisms: Short-term ""single species"" tests with most species of invertebrates have resulted in L(E)C50-values of 2,000 to 60,000 ug.l-1, based on tests with both Cr(III) and Cr(VI). Crustaceans, especially cladocerans (Daphnia sp.) are more sensitive, with L(E)C50-values of 10 to 500 ug.l-1. In general, fish are less sensitive than invertebrates: LC50-values for fish are 3,000 to 190,000 ug.l-1. The toxicity of Cr(VI) increases with decreasing pH and hardness of the water. Long-term ""single species"" tests with Cr(VI) have resulted in NOEC-values of 0.35 to 6,650 ug.l- 1. Relatively low values have been reported for organisms of different, important taxonomic groups, namely algae, crustaceans and fish. In general, fish are less sensitive than invertebrates. Long-term tests with Cr(III) have resulted in NOEC-values of 48 to 330 ug.l-l. In experimental micro-ecosystems (algae) a concentration of 100 ug Cr(VI).l-1 has resulted in a reduction of diatom abundance and diversity. Toxicity to marine organisms: Short-term ""single species"" tests with Cr(VI) have resulted in L(E)C50-values of 2,000 to 105,000 ug Cr(VI).l-1; these values are based on tests with both invertebrates and vertebrates. The lowest values have been reported for crustaceans and polychaete worms. L(E)C50-values based on tests with Cr(III) are 10,000 to 56,000 ug Cr(III).l-1. Long-term ""single species"" tests with Cr(VI) have resulted in NOEC-values of 13 to 770 ug Cr(VI).l-1. The only available NOEC resulting from a test with Cr(III) is 50,400 ug Cr(III).l-1; in this test only 20 ug Cr(III).l-1 was found to be dissolved (0.1 um). Based on these NOEC-values and additional data it is concluded that Cr(III) is less toxic than Cr(VI) in sea water. Terrestrial organisms: Toxicity: In some short-term experiments effects on microbes (numbers, diversity) and microbe-mediated processes (respiration, ammonification, nitrification, enzym-activities) have been reported at concentrations of 25 to 100 mg.kg-1 dry weight [Cr(III) or ""chromium""] and 1 to 10 mg Cr(VI).kg-1. However, in most short-term experiments and in long-term experiments no effects have been reported at concentrations up to 200 mg.kg-1 (dry weight) [Cr(III) or ""chromium""]. In a test with the earthworm Eisenia Andrei, a concentration of 1,000 mg Cr(III).kg-1 dry weight resulted in adverse effects on growth and reproduction. The resulting NOEC is 300 mg Cr(III).kg- 1 dry weight. In two tests in which other earthworm species were exposed to Cr(VI), concentrations of 2 and 10 mg Cr(VI).kg-1, respectively, resulted in increased mortality. Relevant data on other terrestrial organisms are not available."
1238489,Cleven et al. 1990,Integrated criteria document chromium,"Human Toxicity: Cr(III) is an essential trace element for mammals. It is estimated that the minimum requirement for adults is provided by a daily dietary intake of 2 to 8 ug Cr(III), corresponding to 0.03 to 0.13.kg-1 body weight per day. Cr(VI) is considered to be a genotoxic carcinogen in mammals, including man. Therefore a threshold value below which Cr(VI) is not carcinogenic cannot be established. Parenteral administration of either Cr(III) or Cr(VI) to pregnant hamsters and mice in specific teratogenicity studies resulted in increased mortality and malformations in the offspring, among other effects. Developmental toxicity tests in which animals were exposed orally or by inhalation are very limited and definite conclusions about the risk to man cannot therefore be drawn. Oral exposure: The available oral studies on Cr(III) are considered to be too limited to establish a maximum acceptable daily intake. Based on feeding studies with insoluble chromic(III) oxide pigment (Cr2O3), a no-effect dose of 1210 mg Cr(III).kg-1 body weight per day was established; assuming an (estimated) fractional absorption value of 0.5%, this is equivalent to 6 mg absorbed Cr(III).kg-1 body weight per day. Based on a study in which animals received relatively soluble chromic(III) chloride (CrCl3) in drinking water, a no-effect dose of 2.5 mg Cr(III).kg-1 body weight per day was established; assuming a fractional absorption value of 5%, this corresponds to 0.125 mg absorbed Cr(III).kg-1 body weight per day. Since Cr(VI) is considered to be a genotoxic carcinogen, exposure to Cr(VI)should be as low as possible. - Exposure by inhalation Exposure to Cr(III) by inhalation results in a daily intake which is less than 0.1% of the dietary intake (see evaluation, chapter 7). Since there are no indications that inhalation of Cr(III)) causes different effects to oral intake, only exposure to Cr(VI) by inhalation is considered to be relevant. Although differences have been found in the carcinogenic potency of different Cr(VI) compounds, it is not possible to quantify these differences. The ""unit risk"" of 40 x 10E-3, calculated by the World Health Organization (WHO, 1987), defined as ""the extra lung cancer risk occurring in a hypothetical population in which all individuals are exposed throughout their whole lives to a concentration of 1 ug Cr(VI).m3 of air"", is considered to be the best estimate of the carcinogenic potency of Cr(VI). Assuming an acceptable risk of 1 x 10E-6 (one extra case of lung cancer per million persons exposed lifelong), this risk corresponds to an airborne concentration of 25 x 10E-6 ug Cr(VI).m3 [0.025 ng Cr(VI).m3]. Environmental fate: Chromium occurs in the environment in two oxidation states, Cr(III) and Cr(VI). In terms of effects, Cr(VI) is the most important (see chapter 5). The occurrence of a particular Cr(III)/Cr(VI) distribution depends mainly on the existing redox potential, the pH, and the presence of oxidants and reductants. Cr(VI) is readily reduced to Cr(III) by, for example, organic matter. Powerful oxidants are required for the oxidation of Cr(III) to Cr(VI), such as manganese dioxide in soil and surface water and, for example, ozone in the air. Cr(VI) always occurs as a negatively charged oxy compound, CrO4 or HCrO4. It does not form complexes and is adsorbed at relatively low pH values. Cr(III) is a positive ion in an aqueous environment, which can form hydroxides and complexes and is adsorbed at relatively high pH values. Cr(III) compounds are kinetically stable. Cr(III) is the main species in soil. In surface water the speciation of chromium can very from place to place, and relatively high percentages of Cr(VI) have been observed locally. No conclusive answer can be given regarding the percentage of Cr(VI) in the atmosphere because of analytical problems; it may vary from 0.01 to 30% of the total chromium concentration. The adsorption of Cr(III) onto soil material is a non-linear process. Distribution coefficients range between 30.10E3 and 300.10E3 l.kg-1. Chromium bound to organic matter represents nly a small fraction of the total bound chromium in the soil. The distribution coefficients in Dutch surface waters vary from 200.10E3 to 800.10E3 l.kg-1. The behaviour of chromium in surface water is mostly similar to that of other heavy metals as regards sedimentation where rivers discharge into freshwater basins and salt water. Release of chromium from sediments depends on resuspension, followed by desorption in the surface water, rather than on adjustment of equilibrium in the sediment followed by diffusion over the sediment-water gradient. In the atmosphere chromium is bound to the fine fraction of the aerosol. The deposition velocity of chromium is 0.35 cm.s-1. The average rate of removal of chromium by dry deposition is about 1.5% per hour, which is estimated to be 3-4% because of wet deposition. On the basis of this, the average atmospheric residence time under the conditions pertaining in the Netherlands is estimated at about 20 hours. Accumulation of chromium in biota, both aquatic and terrestrial, is negligible; accumulation through food chains is considered to be unlikely. Ecotoxicity: Aquatic organisms: Accumulation: The highest chromium concentrations, up to 1000-3000 mg.kg-1 dry weight, have been found in experimental studies with unicellular algae. The accumulation of chromium in freshwater algae is predominantly a physicochemical (adsorption) process. In accumulation studies with invertebrates (molluscs and worms), BCFs ranging from 125 to 200 have been measured for exposure to both Cr(III) and Cr(VI). In a laboratory study, exposure of two species of marine molluscs (including the common edible Mytilus edulis) to as much as 1000 ug Cr(III).l-1 in natural sea water resulted in much higher concentrations: 430 and 765 mg.kg-1 dry weight, respectively. Concentrations in different species of fish (5 mg.kg-1 wet weight) are much lower than those in invertebrates. Chromium levels in omnivorous and carnivorous species of fish were found to be similar, indicating that there is no relationship with feeding habits. The concentrations given for invertebrates and vertebrates (fish) apply to both freshwater and seawater organisms. It can be concluded that chromium is accumulated to a limited extent by aquatic invertebrates and vertebrates. Toxicity: Since the vast amount of literature data on chromium includes many data on toxicity after long-term exposure, this section has focused especially on this aspect. Unless otherwise stated, the concentrations reported herein are ""total"" chromium concentrations (""dissolved"" [particle size 0.45 um] plus ""undissolved""), expressed in ug Cr.l-1 Toxicity to freshwater organisms: Short-term (24-96 hours) ""single species"" tests with most species of invertebrates have resulted in EC50 and LC50 values of 2,000 to 60,000 ug.l-1, based on tests with both Cr(III) and Cr(VI). Crustaceans, especially cladocerans (Daphnia sp.) are the most sensitive invertebrates, with many acute L(E)C50 values in the 10 to 500 ug.l-1 range. Most of these values are based on tests with Cr(VI). In general, fish are slightly less sensitive than invertebrates: acute LC50's range from 3,000 to 190,000 ug.l-1, based on tests with both Cr(III) and Cr(VI). Abiotic factors which may have a major influence on the toxicity of Cr(VI) are the hardness and pH of the water: the lowest L(E)C50 values have been found at low hardness (ca 50 mg.l-1 as CaC03) and low pH (<7). Long-term single ""species tests"" (n = 35 species) with Cr(VI) have resulted in NOEC values of 0.35 to 6,650 ug Cr(VI).l-1. The extremely low value of 0.35 ug Cr(VI).l-1 was found in a test with the diatom Stephanodiscus hantzschii in very soft water (hardness 8 mg.l-1 as CaCO3), a species which is common in hard, eutrophic waters. Relatively low values (10 to 100 ug Cr(VI).l- 1) have been reported for representatives of important taxonomic groups, namely algae, crustaceans and fish. In general, fish are less sensitive than algae and invertebrates. The few NOEC values from long-term tests (n = 4 species) with Cr(III) range from 48 to 330 ug Cr(III).l- 1 ( OECs from secondary literature sources have been disregarded because the reliability and test conditions could not be ascertained). In experimental micro-ecosystems (algae) a concentration of 100 ug Cr(VI).l-1 has resulted in changes in the community composition. Toxicity to marine organisms: Short-term ""single species"" tests with 18 different species of both invertebrates and vertebrates have resulted in L(E)C50 values of 2,000 to 105,000 ug Cr(VI).l-1. The lowest values (less than or equal to 7,500 ug Cr(VI).l-1) have been reported for crustaceans and polychaete worms. The few L(E)C50 values for Cr(III), 10,000 to 56,000 ug Cr(III).l-1 (n = 3 species) lie in the same range as those for Cr(VI). Long-term ""single species"" tests (n = 5 species) with Cr(VI) have resulted in NOECs of 13 to 770 ug Cr(VI).l-1, the lowest value being found for a species of worm. The only available NOEC resulting from a test with Cr(III) is 50,400 ug.l-1 ""total"" Cr(III); in this test only 20 ug.l-1 was found to be ""dissolved"" Cr(III) (less than 0.1 um). Based on this NOEC value and two NOLC values (greater than or equal to 10,000 ug Cr(III).l-1), it is concluded that Cr(III) is less toxic than Cr(VI) in sea water, which is explained by the poor solubility of Cr(III) in sea water. In an experimental micro-ecosystem consisting of algae, an inverse relationship was found between toxicity and salinity. At ""low"" salinities (0.03 o/oo and over), a concentration of 100 ug Cr(VI).l-1 either completely eliminated growth or greatly reduced the rate of growth, whereas at ""medium"" to ""high"" salinities (up to 32 o/oo) growth was not affected. Terrestrial organisms: Most data in this section refer to Cr(III), by far the most stable form of chromium in soils (see chapter 3). Toxicity: Invertebrates: In a test with the earthworm Eisenia andrei in an artificial soil (8% clay, 8% ?C, pH 6.0), only the highest concentration tested (1000 mg Cr(III).kg-1 dry weight) resulted in adverse effects on growth and reproduction; the NOEC is 300 mg Cr(III).kg-1 dry weight (based on measured concentrations). In this test the worms were exposed for 3 weeks to treated soil (Cr(III) was added to 3-week recovery period in untreated soil. The only other test in which earthworms were exposed to Cr(III) is considered to be outside the scope of this document because of the method used (soil covered with chromium-treated sludge). Cr(VI) appears to be much more toxic than Cr(III): two tests with species of earthworms not found in the Netherlands resulted in increased mortality after 8 weeks of exposure to the lowest concentrations tested, 2 and 10 mg Cr(VI).kg-1, respectively. In both tests the worms were transferred once a week to fresh soil treated with a potassium dichromate solution. (Shortened)","Integrated criteria document chromium Abs: Human Toxicity: Cr(III) is an essential trace element for mammals. It is estimated that the minimum requirement for adults is provided by a daily dietary intake of 2 to 8 ug Cr(III), corresponding to 0.03 to 0.13.kg-1 body weight per day. Cr(VI) is considered to be a genotoxic carcinogen in mammals, including man. Therefore a threshold value below which Cr(VI) is not carcinogenic cannot be established. Parenteral administration of either Cr(III) or Cr(VI) to pregnant hamsters and mice in specific teratogenicity studies resulted in increased mortality and malformations in the offspring, among other effects. Developmental toxicity tests in which animals were exposed orally or by inhalation are very limited and definite conclusions about the risk to man cannot therefore be drawn. Oral exposure: The available oral studies on Cr(III) are considered to be too limited to establish a maximum acceptable daily intake. Based on feeding studies with insoluble chromic(III) oxide pigment (Cr2O3), a no-effect dose of 1210 mg Cr(III).kg-1 body weight per day was established; assuming an (estimated) fractional absorption value of 0.5%, this is equivalent to 6 mg absorbed Cr(III).kg-1 body weight per day. Based on a study in which animals received relatively soluble chromic(III) chloride (CrCl3) in drinking water, a no-effect dose of 2.5 mg Cr(III).kg-1 body weight per day was established; assuming a fractional absorption value of 5%, this corresponds to 0.125 mg absorbed Cr(III).kg-1 body weight per day. Since Cr(VI) is considered to be a genotoxic carcinogen, exposure to Cr(VI)should be as low as possible. - Exposure by inhalation Exposure to Cr(III) by inhalation results in a daily intake which is less than 0.1% of the dietary intake (see evaluation, chapter 7). Since there are no indications that inhalation of Cr(III)) causes different effects to oral intake, only exposure to Cr(VI) by inhalation is considered to be relevant. Although differences have been found in the carcinogenic potency of different Cr(VI) compounds, it is not possible to quantify these differences. The ""unit risk"" of 40 x 10E-3, calculated by the World Health Organization (WHO, 1987), defined as ""the extra lung cancer risk occurring in a hypothetical population in which all individuals are exposed throughout their whole lives to a concentration of 1 ug Cr(VI).m3 of air"", is considered to be the best estimate of the carcinogenic potency of Cr(VI). Assuming an acceptable risk of 1 x 10E-6 (one extra case of lung cancer per million persons exposed lifelong), this risk corresponds to an airborne concentration of 25 x 10E-6 ug Cr(VI).m3 [0.025 ng Cr(VI).m3]. Environmental fate: Chromium occurs in the environment in two oxidation states, Cr(III) and Cr(VI). In terms of effects, Cr(VI) is the most important (see chapter 5). The occurrence of a particular Cr(III)/Cr(VI) distribution depends mainly on the existing redox potential, the pH, and the presence of oxidants and reductants. Cr(VI) is readily reduced to Cr(III) by, for example, organic matter. Powerful oxidants are required for the oxidation of Cr(III) to Cr(VI), such as manganese dioxide in soil and surface water and, for example, ozone in the air. Cr(VI) always occurs as a negatively charged oxy compound, CrO4 or HCrO4. It does not form complexes and is adsorbed at relatively low pH values. Cr(III) is a positive ion in an aqueous environment, which can form hydroxides and complexes and is adsorbed at relatively high pH values. Cr(III) compounds are kinetically stable. Cr(III) is the main species in soil. In surface water the speciation of chromium can very from place to place, and relatively high percentages of Cr(VI) have been observed locally. No conclusive answer can be given regarding the percentage of Cr(VI) in the atmosphere because of analytical problems; it may vary from 0.01 to 30% of the total chromium concentration. The adsorption of Cr(III) onto soil material is a non-linear process. Distribution coefficients range between 30.10E3 and 300.10E3 l.kg-1. Chromium bound to organic matter represents nly a small fraction of the total bound chromium in the soil. The distribution coefficients in Dutch surface waters vary from 200.10E3 to 800.10E3 l.kg-1. The behaviour of chromium in surface water is mostly similar to that of other heavy metals as regards sedimentation where rivers discharge into freshwater basins and salt water. Release of chromium from sediments depends on resuspension, followed by desorption in the surface water, rather than on adjustment of equilibrium in the sediment followed by diffusion over the sediment-water gradient. In the atmosphere chromium is bound to the fine fraction of the aerosol. The deposition velocity of chromium is 0.35 cm.s-1. The average rate of removal of chromium by dry deposition is about 1.5% per hour, which is estimated to be 3-4% because of wet deposition. On the basis of this, the average atmospheric residence time under the conditions pertaining in the Netherlands is estimated at about 20 hours. Accumulation of chromium in biota, both aquatic and terrestrial, is negligible; accumulation through food chains is considered to be unlikely. Ecotoxicity: Aquatic organisms: Accumulation: The highest chromium concentrations, up to 1000-3000 mg.kg-1 dry weight, have been found in experimental studies with unicellular algae. The accumulation of chromium in freshwater algae is predominantly a physicochemical (adsorption) process. In accumulation studies with invertebrates (molluscs and worms), BCFs ranging from 125 to 200 have been measured for exposure to both Cr(III) and Cr(VI). In a laboratory study, exposure of two species of marine molluscs (including the common edible Mytilus edulis) to as much as 1000 ug Cr(III).l-1 in natural sea water resulted in much higher concentrations: 430 and 765 mg.kg-1 dry weight, respectively. Concentrations in different species of fish (5 mg.kg-1 wet weight) are much lower than those in invertebrates. Chromium levels in omnivorous and carnivorous species of fish were found to be similar, indicating that there is no relationship with feeding habits. The concentrations given for invertebrates and vertebrates (fish) apply to both freshwater and seawater organisms. It can be concluded that chromium is accumulated to a limited extent by aquatic invertebrates and vertebrates. Toxicity: Since the vast amount of literature data on chromium includes many data on toxicity after long-term exposure, this section has focused especially on this aspect. Unless otherwise stated, the concentrations reported herein are ""total"" chromium concentrations (""dissolved"" [particle size 0.45 um] plus ""undissolved""), expressed in ug Cr.l-1 Toxicity to freshwater organisms: Short-term (24-96 hours) ""single species"" tests with most species of invertebrates have resulted in EC50 and LC50 values of 2,000 to 60,000 ug.l-1, based on tests with both Cr(III) and Cr(VI). Crustaceans, especially cladocerans (Daphnia sp.) are the most sensitive invertebrates, with many acute L(E)C50 values in the 10 to 500 ug.l-1 range. Most of these values are based on tests with Cr(VI). In general, fish are slightly less sensitive than invertebrates: acute LC50's range from 3,000 to 190,000 ug.l-1, based on tests with both Cr(III) and Cr(VI). Abiotic factors which may have a major influence on the toxicity of Cr(VI) are the hardness and pH of the water: the lowest L(E)C50 values have been found at low hardness (ca 50 mg.l-1 as CaC03) and low pH (<7). Long-term single ""species tests"" (n = 35 species) with Cr(VI) have resulted in NOEC values of 0.35 to 6,650 ug Cr(VI).l-1. The extremely low value of 0.35 ug Cr(VI).l-1 was found in a test with the diatom Stephanodiscus hantzschii in very soft water (hardness 8 mg.l-1 as CaCO3), a species which is common in hard, eutrophic waters. Relatively low values (10 to 100 ug Cr(VI).l- 1) have been reported for representatives of important taxonomic groups, namely algae, crustaceans and fish. In general, fish are less sensitive than algae and invertebrates. The few NOEC values from long-term tests (n = 4 species) with Cr(III) range from 48 to 330 ug Cr(III).l- 1 ( OECs from secondary literature sources have been disregarded because the reliability and test conditions could not be ascertained). In experimental micro-ecosystems (algae) a concentration of 100 ug Cr(VI).l-1 has resulted in changes in the community composition. Toxicity to marine organisms: Short-term ""single species"" tests with 18 different species of both invertebrates and vertebrates have resulted in L(E)C50 values of 2,000 to 105,000 ug Cr(VI).l-1. The lowest values (less than or equal to 7,500 ug Cr(VI).l-1) have been reported for crustaceans and polychaete worms. The few L(E)C50 values for Cr(III), 10,000 to 56,000 ug Cr(III).l-1 (n = 3 species) lie in the same range as those for Cr(VI). Long-term ""single species"" tests (n = 5 species) with Cr(VI) have resulted in NOECs of 13 to 770 ug Cr(VI).l-1, the lowest value being found for a species of worm. The only available NOEC resulting from a test with Cr(III) is 50,400 ug.l-1 ""total"" Cr(III); in this test only 20 ug.l-1 was found to be ""dissolved"" Cr(III) (less than 0.1 um). Based on this NOEC value and two NOLC values (greater than or equal to 10,000 ug Cr(III).l-1), it is concluded that Cr(III) is less toxic than Cr(VI) in sea water, which is explained by the poor solubility of Cr(III) in sea water. In an experimental micro-ecosystem consisting of algae, an inverse relationship was found between toxicity and salinity. At ""low"" salinities (0.03 o/oo and over), a concentration of 100 ug Cr(VI).l-1 either completely eliminated growth or greatly reduced the rate of growth, whereas at ""medium"" to ""high"" salinities (up to 32 o/oo) growth was not affected. Terrestrial organisms: Most data in this section refer to Cr(III), by far the most stable form of chromium in soils (see chapter 3). Toxicity: Invertebrates: In a test with the earthworm Eisenia andrei in an artificial soil (8% clay, 8% ?C, pH 6.0), only the highest concentration tested (1000 mg Cr(III).kg-1 dry weight) resulted in adverse effects on growth and reproduction; the NOEC is 300 mg Cr(III).kg-1 dry weight (based on measured concentrations). In this test the worms were exposed for 3 weeks to treated soil (Cr(III) was added to 3-week recovery period in untreated soil. The only other test in which earthworms were exposed to Cr(III) is considered to be outside the scope of this document because of the method used (soil covered with chromium-treated sludge). Cr(VI) appears to be much more toxic than Cr(III): two tests with species of earthworms not found in the Netherlands resulted in increased mortality after 8 weeks of exposure to the lowest concentrations tested, 2 and 10 mg Cr(VI).kg-1, respectively. In both tests the worms were transferred once a week to fresh soil treated with a potassium dichromate solution. (Shortened)"
1238488,Anonymous 1973,Chromium and inorganic chromium compounds,"In many experiments, various chromium compounds have been shown to induce tumours in mice and rats. Calcium chromate has been found to be carcinogenic by several routes of administration, producing epithelial tumours of the lung by intrabronchial implantation and sarcomas by intramuscular and intrapleural administration to rats. Of the other chromium salts tested in the rat by intramuscular and intrapleural administration, chromic chromate and zinc chromate hydroxide were highly evocative of sarcomas at the site of injection in the rat, whilst barium chromate, lead chromate, chromic acetate and sodium dichromate were inactive or practically inactive. Strontium chromate was tested only by intramuscular implantation and evoked many local sarcomas. Studies involving oral administration of chromic acetate in mice and rats which gave negative results were considered inadequate because the level of exposure was low. There is an excessive risk of lung cancer among workers in the chromate-producing industry. It is likely that exposure to one or more chromium compounds is responsible, but the identity of this or these is not known. There is no evidence that non-occupational exposure to chromium constitutes a cancer hazard.","Chromium and inorganic chromium compounds Abs: In many experiments, various chromium compounds have been shown to induce tumours in mice and rats. Calcium chromate has been found to be carcinogenic by several routes of administration, producing epithelial tumours of the lung by intrabronchial implantation and sarcomas by intramuscular and intrapleural administration to rats. Of the other chromium salts tested in the rat by intramuscular and intrapleural administration, chromic chromate and zinc chromate hydroxide were highly evocative of sarcomas at the site of injection in the rat, whilst barium chromate, lead chromate, chromic acetate and sodium dichromate were inactive or practically inactive. Strontium chromate was tested only by intramuscular implantation and evoked many local sarcomas. Studies involving oral administration of chromic acetate in mice and rats which gave negative results were considered inadequate because the level of exposure was low. There is an excessive risk of lung cancer among workers in the chromate-producing industry. It is likely that exposure to one or more chromium compounds is responsible, but the identity of this or these is not known. There is no evidence that non-occupational exposure to chromium constitutes a cancer hazard."
1238487,Anonymous 2001,Strontium Chromate,"A TLV-TWA of 0.0005 mg/m3, measured as chromium (Cr), is recommended for occupational exposure to strontium chromate. No published epidemiological or clinical studies of workers exposed to strontium chromate were identified in the open scientific or medical literature. However, long-term oncogenic studies with rodents resulted in statistically significant numbers of implantation-site tumors, including up to a 62% incidence of bronchial carcinomas compared with 0% in pellet-vehicle control animals. Furthermore, strontium chromate is of greater potency for tumorigenesis when compared to the reference carcinogens calcium chromate and methylcholanthrene. For these reasons, an A2, Suspected Human Carcinogen, notation is justified. In addition, for A2 carcinogens with a TLV, worker exposure by all routes should be carefully controlled to levels as low as possible below the TLV. Sufficient data were not available to recommend Skin or SEN notations or a TLV-STEL.","Strontium Chromate Abs: A TLV-TWA of 0.0005 mg/m3, measured as chromium (Cr), is recommended for occupational exposure to strontium chromate. No published epidemiological or clinical studies of workers exposed to strontium chromate were identified in the open scientific or medical literature. However, long-term oncogenic studies with rodents resulted in statistically significant numbers of implantation-site tumors, including up to a 62% incidence of bronchial carcinomas compared with 0% in pellet-vehicle control animals. Furthermore, strontium chromate is of greater potency for tumorigenesis when compared to the reference carcinogens calcium chromate and methylcholanthrene. For these reasons, an A2, Suspected Human Carcinogen, notation is justified. In addition, for A2 carcinogens with a TLV, worker exposure by all routes should be carefully controlled to levels as low as possible below the TLV. Sufficient data were not available to recommend Skin or SEN notations or a TLV-STEL."
1238486,Anonymous 2001,Lead Chromate,"A TLV-TWA of 0.05 mg/m3, measured as lead (Pb), and 0.012 mg/m3, measured as Chromium (Cr), are recommended for occupational exposure to lead chromate to minimize the potential for adverse health effects associated with exposure to lead or to chromium (see current TLV Documentations for Lead and Chromium). These effects may include hypertension, and reproductive and developmental toxicity. These effects may include hypertension, and reproductive and developmental toxicity. An A2, Suspected Human Carcinogen, notation is assigned to lead chromate, based on the experimental animal and epidemiological studies that demonstrated, to a low degree of potency, carcinogenicity for the compound. Sufficient data were not available to recommend Skin or SEN notations or a TLV-STEL. Lead chromate is a substance for which Biological Exposure Indices (BEIs) have been recommended (see BEI Documentation for Lead).","Lead Chromate Abs: A TLV-TWA of 0.05 mg/m3, measured as lead (Pb), and 0.012 mg/m3, measured as Chromium (Cr), are recommended for occupational exposure to lead chromate to minimize the potential for adverse health effects associated with exposure to lead or to chromium (see current TLV Documentations for Lead and Chromium). These effects may include hypertension, and reproductive and developmental toxicity. These effects may include hypertension, and reproductive and developmental toxicity. An A2, Suspected Human Carcinogen, notation is assigned to lead chromate, based on the experimental animal and epidemiological studies that demonstrated, to a low degree of potency, carcinogenicity for the compound. Sufficient data were not available to recommend Skin or SEN notations or a TLV-STEL. Lead chromate is a substance for which Biological Exposure Indices (BEIs) have been recommended (see BEI Documentation for Lead)."
1238485,standards 1998,Chromium and its inorganic compounds. Health-based recommended occupational exposure limits,"Groups at extra risk. Chromium skin contact allergies haven been observed among workers in numerous industrial activities. Sensitized subjects to chromium are at extra risk and should not be placed in jobs where skin contact with chromium and chromium compounds can occur. In contrast with us document, the committee concluded that it is inappropriate to consider people with a dimished lungfunction at extra risk. Assessment of health risk. Chromium trioxide is used in chrome plating, copper stripping, aluminium anodizing, as a catalyst, refractories, in organic synthesis and photography. Occupations in which exposure may occur include: anodizers, copper etchers, electro-platers, glass workers, lithographers, metal workers, oil purifiers, photoengraphers, photographers, process engravers, stainless steel workers, textile workers, painters and welders (Sit79). Theory and practice show that the kinetics and toxic effects induced by chromium compounds depend on the valency of the chromium ion and the water solubility of the compounds. Chromium metal dust (Cro). There are almost no toxicological data on chromium metal dust. Given this lack of scientific data the committee can not establish a HBR-OEL*. This conclusion also implies that the present MAC** value of 0.5 mg/m3, TWA - 8 h should not be considered as health-based. Chromium(ll) compounds (chromium dichloride). Limited relevant data are available on these compounds. It has been shown that chromium(II) is non-genotoxic. No human data are available. The committee can not recommend a health-based occupational exposure limit due to the lack of scientific data. Soluble chromium(III) compounds (chromic acetate, chromic nitrate, chromic chloride hexahydrate, potassium chromic sulphate dodecahydrate). The target organ of chromium(l11) compounds after inhalatory exposure are the lungs. A MOAEL of 0.6 mg/m3 was found in rabbits exposed to soluble chromium(l11) compounds by inhalation for six hours per day, five days per week during four to six weeks. At this concentration morphological as well as functional changes in the alveolar macrophages were found. Human data are lacking. Chromium(III) compounds have been shown to be not mutagenic, nor clastogenic, nor carcinogenic. The committee considers chromium(III) compounds to be non nephrotoxic. In establishing a HBR-OEL a large safety factor for the extrapolation of animal data to humans is not indicated since chromium(l11) compounds induce only local effects. The committee recommends a HBR-OEL of 0.06 mg/m3 for soluble chromium(l11) compounds, TWA - 8 hour by dividing the MOAEL value of 0.6 mg/m3 in rabbits by a factor of 10. This safety factor is the product of a factor of 3 for interspecies variations and 3 for using a MOAEL as starting point resulting in a safety factor 10. The HBR-OEL should be applied to inhalable dusts. Insoluble chromium(l11) compounds (chromic oxide, chromic phosphate, chromic sulphate). There are almost no recent toxicological data on insoluble chromium(l11) compound In its previous document the committee did not make a distinction between soluble and insoluble chromium(l11) compounds, and did not object against a health-based occupational exposure limit of 0.5 mg/m3, TWA - 8 hour. It was based on only one experiment in hamsters with the lungs as the target organ. No human data are available. Given this lack of data the committee can not recommend a health-based occupational exposure limit for insoluble chromium(III) compounds. Chromium(lV) compounds (chromium dioxide). A long-term inhalation study in rats showed the lungs to be the target organ. A LOAEL of 0.5 mg/m3 was found in a two year study in rats. Exposure to this concentration resulted in slight Type 1I pneumocyte hyperplasis. At higher levels of exposure, hyperplastic Type II pneumocytes and slightly collagenized fibrosis were found. The lungs showed minute fibrotic pleuritis. The committee recommends a HBR-OEL of 0.05 mg/m3 for chromium(lV) compounds, TWA - 8 hour. This value is derived by dividing the LOAEL value in rats of 0.5 mg/m3 by a actor of 10. This safety factor is the product of a factor of 3 for the interspecies variations and three 3 using a LOAEL as the starting point. The HBR-OEL should be applied to inhalable dusts. Chromium(VI) compounds Includes: soluble chromium(VI) compounds (e.g. ammonium dichromate, chromium trioxide, potassium dichromate, sodium dichromate); slightly soluble chromium(VI) compound (e.g. calcium chromate, strontium chromate, zinc chromate); very slightly soluble chromium(VI) compounds (e.g. barium chromate, lead chromate). Several epidemiological studies of workers mainly exposed to zinc chromate (a slightly soluble chromium(VI) compound) report an clear excess of lung cancer mortality. The same holds for lead chromate (a very slightly soluble chromium(VI) compound). No cohort studies of workers that were exclusively exposed to soluble chromium(VI) compounds were found in the literature. However there are some series of lung cancer cases that provide circumstantial evidence for the carcinogenicity of sodium dichromate and potassium dichromate (soluble chromium(VI) compounds). These lung cancer cases were listed by Lang?rd (Lan90). Carcinogenicity studies with experimental animals are scarce and of limited value for human risk estimation, due to limitations in the experimental design. Nevertheless, most of these studies point to a carcinogenic effect of chromium(VI) compounds in the lungs. In any case these studies can certainly not be considered as 'negative' with respect to carcinogenesis. It appears that the carcinogenicity of chromium(VI) compounds in animals varies with the solubility of the compound. Moreover, all chromium(VI) compounds are mutagenic, irrespective of their solubility. How the solubility interferes with the carcinogenic potential of chromium(VI) compounds is not known. The committee draws the following conclusions. Epidemiologica] studies provide clear and unambiguous evidence for carcinogenicity of slightly soluble and very slightly soluble chromium(VI) compounds and circumstantial evidence for the carcinogenicity of soluble chromium(VI) compounds. Experimental animal studies indicate that chromium(VI) compounds possess carcinogenic potential and that there are quantitative differences between soluble, slightly soluble and very slightly soluble chromium(VI) compounds. Therefore, the committee considers all chromium(VI) compounds as carcinogenic. It considers a worst case approach warranted and has therefore selected the study of Mancuso (Man75) on slightly soluble chromium(VI) compounds as a basis for human risk assessment. The committee decided to adopt the data from the EPA as starting point for the estimation of the additional life time cancer risk. The EPA risk assessment was based on the results of the Mancuso study (Man75) complemented with addidional exposure data and follow-up. In agreement with the EPA the committee prefers to use the Mancuso study because of the availability of reliable historic exposure data and the availability of substantial number of observed lung cancer deaths. The EPA used a low-dose linear extrapolation model for the estimation of the cancer risk. A life time (75 years) exposure of I ,ug/m3 chromium(VI) dust entails an additional lung cancer risk of 1.4 *10-2. This risk is calculated on the basis ofthe total chromium concentration in the chromate plant. The EPA noted that the use of total chromium as a surrogate for hexavalent chromium could result in an underestimate ofthe risk by no more than 7 times; on the other hand, underestimation of plant exposures and of smoking habits in the workers could lead to a overestimation of the risk by roughly 4 times. Overall, the EPA found the Mancuso study was the best possible estimate of the risk (EPA84). For the occupational situation the analysis implies that exposure to 8 ug/m2 may result in an addional cancer mortality risk of 1.4 *10-2. Therefore the committee derives an: * Additional cancer mortality risk of 4 x 10-3 after 40 years of occupational exposure to 2 ug/m3. * Additional cancer mortality risk of 4 x 10-5 afte 40 years of occupational exposure to 0.02 ug/m3.","Chromium and its inorganic compounds. Health-based recommended occupational exposure limits Abs: Groups at extra risk. Chromium skin contact allergies haven been observed among workers in numerous industrial activities. Sensitized subjects to chromium are at extra risk and should not be placed in jobs where skin contact with chromium and chromium compounds can occur. In contrast with us document, the committee concluded that it is inappropriate to consider people with a dimished lungfunction at extra risk. Assessment of health risk. Chromium trioxide is used in chrome plating, copper stripping, aluminium anodizing, as a catalyst, refractories, in organic synthesis and photography. Occupations in which exposure may occur include: anodizers, copper etchers, electro-platers, glass workers, lithographers, metal workers, oil purifiers, photoengraphers, photographers, process engravers, stainless steel workers, textile workers, painters and welders (Sit79). Theory and practice show that the kinetics and toxic effects induced by chromium compounds depend on the valency of the chromium ion and the water solubility of the compounds. Chromium metal dust (Cro). There are almost no toxicological data on chromium metal dust. Given this lack of scientific data the committee can not establish a HBR-OEL*. This conclusion also implies that the present MAC** value of 0.5 mg/m3, TWA - 8 h should not be considered as health-based. Chromium(ll) compounds (chromium dichloride). Limited relevant data are available on these compounds. It has been shown that chromium(II) is non-genotoxic. No human data are available. The committee can not recommend a health-based occupational exposure limit due to the lack of scientific data. Soluble chromium(III) compounds (chromic acetate, chromic nitrate, chromic chloride hexahydrate, potassium chromic sulphate dodecahydrate). The target organ of chromium(l11) compounds after inhalatory exposure are the lungs. A MOAEL of 0.6 mg/m3 was found in rabbits exposed to soluble chromium(l11) compounds by inhalation for six hours per day, five days per week during four to six weeks. At this concentration morphological as well as functional changes in the alveolar macrophages were found. Human data are lacking. Chromium(III) compounds have been shown to be not mutagenic, nor clastogenic, nor carcinogenic. The committee considers chromium(III) compounds to be non nephrotoxic. In establishing a HBR-OEL a large safety factor for the extrapolation of animal data to humans is not indicated since chromium(l11) compounds induce only local effects. The committee recommends a HBR-OEL of 0.06 mg/m3 for soluble chromium(l11) compounds, TWA - 8 hour by dividing the MOAEL value of 0.6 mg/m3 in rabbits by a factor of 10. This safety factor is the product of a factor of 3 for interspecies variations and 3 for using a MOAEL as starting point resulting in a safety factor 10. The HBR-OEL should be applied to inhalable dusts. Insoluble chromium(l11) compounds (chromic oxide, chromic phosphate, chromic sulphate). There are almost no recent toxicological data on insoluble chromium(l11) compound In its previous document the committee did not make a distinction between soluble and insoluble chromium(l11) compounds, and did not object against a health-based occupational exposure limit of 0.5 mg/m3, TWA - 8 hour. It was based on only one experiment in hamsters with the lungs as the target organ. No human data are available. Given this lack of data the committee can not recommend a health-based occupational exposure limit for insoluble chromium(III) compounds. Chromium(lV) compounds (chromium dioxide). A long-term inhalation study in rats showed the lungs to be the target organ. A LOAEL of 0.5 mg/m3 was found in a two year study in rats. Exposure to this concentration resulted in slight Type 1I pneumocyte hyperplasis. At higher levels of exposure, hyperplastic Type II pneumocytes and slightly collagenized fibrosis were found. The lungs showed minute fibrotic pleuritis. The committee recommends a HBR-OEL of 0.05 mg/m3 for chromium(lV) compounds, TWA - 8 hour. This value is derived by dividing the LOAEL value in rats of 0.5 mg/m3 by a actor of 10. This safety factor is the product of a factor of 3 for the interspecies variations and three 3 using a LOAEL as the starting point. The HBR-OEL should be applied to inhalable dusts. Chromium(VI) compounds Includes: soluble chromium(VI) compounds (e.g. ammonium dichromate, chromium trioxide, potassium dichromate, sodium dichromate); slightly soluble chromium(VI) compound (e.g. calcium chromate, strontium chromate, zinc chromate); very slightly soluble chromium(VI) compounds (e.g. barium chromate, lead chromate). Several epidemiological studies of workers mainly exposed to zinc chromate (a slightly soluble chromium(VI) compound) report an clear excess of lung cancer mortality. The same holds for lead chromate (a very slightly soluble chromium(VI) compound). No cohort studies of workers that were exclusively exposed to soluble chromium(VI) compounds were found in the literature. However there are some series of lung cancer cases that provide circumstantial evidence for the carcinogenicity of sodium dichromate and potassium dichromate (soluble chromium(VI) compounds). These lung cancer cases were listed by Lang?rd (Lan90). Carcinogenicity studies with experimental animals are scarce and of limited value for human risk estimation, due to limitations in the experimental design. Nevertheless, most of these studies point to a carcinogenic effect of chromium(VI) compounds in the lungs. In any case these studies can certainly not be considered as 'negative' with respect to carcinogenesis. It appears that the carcinogenicity of chromium(VI) compounds in animals varies with the solubility of the compound. Moreover, all chromium(VI) compounds are mutagenic, irrespective of their solubility. How the solubility interferes with the carcinogenic potential of chromium(VI) compounds is not known. The committee draws the following conclusions. Epidemiologica] studies provide clear and unambiguous evidence for carcinogenicity of slightly soluble and very slightly soluble chromium(VI) compounds and circumstantial evidence for the carcinogenicity of soluble chromium(VI) compounds. Experimental animal studies indicate that chromium(VI) compounds possess carcinogenic potential and that there are quantitative differences between soluble, slightly soluble and very slightly soluble chromium(VI) compounds. Therefore, the committee considers all chromium(VI) compounds as carcinogenic. It considers a worst case approach warranted and has therefore selected the study of Mancuso (Man75) on slightly soluble chromium(VI) compounds as a basis for human risk assessment. The committee decided to adopt the data from the EPA as starting point for the estimation of the additional life time cancer risk. The EPA risk assessment was based on the results of the Mancuso study (Man75) complemented with addidional exposure data and follow-up. In agreement with the EPA the committee prefers to use the Mancuso study because of the availability of reliable historic exposure data and the availability of substantial number of observed lung cancer deaths. The EPA used a low-dose linear extrapolation model for the estimation of the cancer risk. A life time (75 years) exposure of I ,ug/m3 chromium(VI) dust entails an additional lung cancer risk of 1.4 *10-2. This risk is calculated on the basis ofthe total chromium concentration in the chromate plant. The EPA noted that the use of total chromium as a surrogate for hexavalent chromium could result in an underestimate ofthe risk by no more than 7 times; on the other hand, underestimation of plant exposures and of smoking habits in the workers could lead to a overestimation of the risk by roughly 4 times. Overall, the EPA found the Mancuso study was the best possible estimate of the risk (EPA84). For the occupational situation the analysis implies that exposure to 8 ug/m2 may result in an addional cancer mortality risk of 1.4 *10-2. Therefore the committee derives an: * Additional cancer mortality risk of 4 x 10-3 after 40 years of occupational exposure to 2 ug/m3. * Additional cancer mortality risk of 4 x 10-5 afte 40 years of occupational exposure to 0.02 ug/m3."
1238484,Anonymous 2005,"Chromium Trioxide, Sodium Chromate, Sodium Dichromate, Ammonium Dichromate and Potassium Dichromate","Environment The environmental risk characterisation considers the production of the five chromium (VI) substances and their use in the following areas: pigment production; chromium oxide production; tanning salt production; wood preservation (formulation and use); metal treatment (formulation and use in electroplating, passivating, anodising and brightening); and mordant dyeing. The leaching of chromium from preservative-treated wood in direct contract with water is also included. A number of other uses were also considered and found to have negligible releases: chromium metal production; chromium dioxide production; Montan wax production. The use of chromium (VI) in the oxidation of sulphur dyes no longer occurs in Europe. There are other sources of chromium release to the environment, both anthropogenic and natural, but there are not considered in this assessment. The assessment is based on the added local risk from the activities included. It is recognised that the wider background contribution may need to be considered when evaluating possible risk reduction measures. For the aquatic compartment, including sediment, all the PEC/PNEC ratios are above one with the exception of two production sites and the use in mordant dyeing. Risk reduction measures are needed for surface water. The PNEC for sediment could be refined, but no work is proposed at present as the risk reduction measures for water will also reduce the risk to sediment organisms. Risks are identified to micro-organisms in waste water treatment plants for all scenarios except production, wood preservative application and mordant dyeing. For the terrestrial environment, risks are identified for all scenarios except production and mordant dyeing. For indirect exposure through the food chain, the risk characterisation based on calculated concentrations in fish shows no risk from any of the scenarios. In contrast, the risk characterisation based on calculated concentrations in mussels shows a risk to all but there scenarios - production, wood preservative application and mordant dyeing. Further work could be carried out to refine this risk characterisation, but risk reduction measures for surface water will also lead to reduced risk for this endpoint and therefore no specific work is proposed. The terrestrial food chain risk characterisation shows no risk for any scenario. Conclusion (i) There is a need for further information and/or testing. This conclusion applies to sediment for all areas except for mordant dyeing. The effect concentration used in the risk characterisation is derived from data for aquatic organisms, and could be refined with data for sediment dwelling organisms. Although there may be value in trying to establish the relative sensitivity of sediment and aquatic organisms, measures to reduce water concentrations as a result of the assessment will also lead to reduced sediment levels. No further testing is proposed as the present. This conclusion also applies to indirect exposure through the food chain for the mussel based food chain, for all areas except production, wood preservative application and mordant dyeing. Further work could be done to test whether the mussel-based food chain is of concern, for example through further investigation of the uptake of chromium into organisms other than fish, characterisation of the nature of the chromium in organisms and consideration of the toxicity of chromium in other forms to organisms consuming prey containing chromium. However it should be noted that reductions in the emissions of chromium (VI) to water will reduce the estimated levels in biota as well. At present it is not proposed to carry out any further work, but to await the development of risk reduction measures. Conclusion (ii): There is at present no need for further information and/or testing and for risk reduction measures beyond those which are being applied already. For the aquatic compartment this conclusion applies to the use in mordant dyeing and to production (two Bites only). For sediment this conclusion applies to use in mordant dyeing. For waste water treatment plants, this conclusion applies to production, wood preservative application, anodising and mordant dyeing. For the terrestrial compartment, this conclusion applies to production and to mordant dyeing. This conclusion also applies to all areas for the air compartment and for indirect exposure though the fish-based food chain. Conclusion (iii) There is a need for limning the risks; risk reduction measures which are already being applied shall be taken into account. This conclusion applies to all areas for the aquatic, and terrestrial compartments, with the exception of mordant dyeing (both compartments) and production (terrestrial only, although the conclusion only applies to one production site for the aquatic). It also applies to waste water treatment plants for all areas, with the exception of production, wood preservative application, anodising and mordant dyeing. Human health Human health (toxicity) Occupational exposure Conclusion (i) There is a need for further information and/or testing. Conclusion (i) is reached for repeated dose toxicity to the respiratory tract and the kidney. It is not possible to formally calculate an MOS for these effects since no NOAELs have been identified. Hence it is not possible to assess risk under contemporary working conditions. Further exposure-response information for respiratory tract and kidney effects is required. Conclusion (ii) There is at present no need for further information and/or testing and no need for risk reduction measures beyond those which are being applied already. Conclusion (ii) is reached for acute toxicity for full shift exposures since MOS values indicate there is no cause for concern. Conclusion (iii) There is a need for limning the risks; risk reduction measures which are already being applied shall be taken into account. In view of the genotoxic and carcinogenic properties of these Cr(VI) compounds, there are concerns for all exposure scenarios. In addition, there are concerns for acute toxicity as a result of short-term peak exposures, skin and eye irritation, respiratory tract sensory irritation, skin sensitisation, occupational asthma and reproductive toxicity (fertility and developmental toxicity). Conclusion (iii) is reached for these endpoints. Consumer assessment Conclusion (ii) There is at present no need for further information and/or testing and no need for risk reduction measures beyond those which are being applied already. Conclusion (ii) is reached for all endpoints other than mutagenicity and carcinogenicity for the handling of CCA treated wood, both for adults and for children exposed via wooden playing structures. Conclusion (iii) There is a need for limiting the risks; risk reduction measures which are already being applied shall be taken into account. Conclusion (iii) is reached for mutagenicity and carcinogenicity because no threshold below which there would be no risk to human health can be identified for these endpoints. However, it is noted that exposure levels are very low. No formal risk characterisation has been conducted for consumer exposure to wet CCA treated wood. In the UK, the supply of wood not fully dried following CCA treatment is prohibited as a condition of approval under the Control of Pesticides Regulations (1986). Similar controls may already exist in all other Member States. However, if specific controls were not available in each Member State, then there would be concerns for all relevant human health endpoints Indirect exposure via the environment Conclusions are presented for both local and regional scenarios together. Conclusion (ii) There is at present no need for further information and/or testing and no need for risk reduction measures beyond those which are being applied already. Conclusion (ii) is reached for all endpoints other than mutagenicity and carcinogenicity. Conclusion (iii) There is a need for limiting the risks; risk reduction measures which are already being applied shall be taken into account. Conclusion (iii) is reached for mutagenicity and carcinogenicity because no threshold below which there would be no risk to human health can be identified for these endpoints. However, it is noted that exposure levels are very low. Combined exposure The combination of consumer exposure with indirect exposure via the environment does not produce significantly higher total exposures than those calculated for the separate individual contributions and therefore conclusion (ii) or, where appropriate, conclusion (iii) also applies to combined exposure. Human Health (physico-chemical properties) Given the level of control in manufacture and use the risks from physico-chemical properties are small. Conclusion (ii) There is at present no need for further information and/or testing and no need for risk reduction measures beyond those which are being applied already.","Chromium Trioxide, Sodium Chromate, Sodium Dichromate, Ammonium Dichromate and Potassium Dichromate Abs: Environment The environmental risk characterisation considers the production of the five chromium (VI) substances and their use in the following areas: pigment production; chromium oxide production; tanning salt production; wood preservation (formulation and use); metal treatment (formulation and use in electroplating, passivating, anodising and brightening); and mordant dyeing. The leaching of chromium from preservative-treated wood in direct contract with water is also included. A number of other uses were also considered and found to have negligible releases: chromium metal production; chromium dioxide production; Montan wax production. The use of chromium (VI) in the oxidation of sulphur dyes no longer occurs in Europe. There are other sources of chromium release to the environment, both anthropogenic and natural, but there are not considered in this assessment. The assessment is based on the added local risk from the activities included. It is recognised that the wider background contribution may need to be considered when evaluating possible risk reduction measures. For the aquatic compartment, including sediment, all the PEC/PNEC ratios are above one with the exception of two production sites and the use in mordant dyeing. Risk reduction measures are needed for surface water. The PNEC for sediment could be refined, but no work is proposed at present as the risk reduction measures for water will also reduce the risk to sediment organisms. Risks are identified to micro-organisms in waste water treatment plants for all scenarios except production, wood preservative application and mordant dyeing. For the terrestrial environment, risks are identified for all scenarios except production and mordant dyeing. For indirect exposure through the food chain, the risk characterisation based on calculated concentrations in fish shows no risk from any of the scenarios. In contrast, the risk characterisation based on calculated concentrations in mussels shows a risk to all but there scenarios - production, wood preservative application and mordant dyeing. Further work could be carried out to refine this risk characterisation, but risk reduction measures for surface water will also lead to reduced risk for this endpoint and therefore no specific work is proposed. The terrestrial food chain risk characterisation shows no risk for any scenario. Conclusion (i) There is a need for further information and/or testing. This conclusion applies to sediment for all areas except for mordant dyeing. The effect concentration used in the risk characterisation is derived from data for aquatic organisms, and could be refined with data for sediment dwelling organisms. Although there may be value in trying to establish the relative sensitivity of sediment and aquatic organisms, measures to reduce water concentrations as a result of the assessment will also lead to reduced sediment levels. No further testing is proposed as the present. This conclusion also applies to indirect exposure through the food chain for the mussel based food chain, for all areas except production, wood preservative application and mordant dyeing. Further work could be done to test whether the mussel-based food chain is of concern, for example through further investigation of the uptake of chromium into organisms other than fish, characterisation of the nature of the chromium in organisms and consideration of the toxicity of chromium in other forms to organisms consuming prey containing chromium. However it should be noted that reductions in the emissions of chromium (VI) to water will reduce the estimated levels in biota as well. At present it is not proposed to carry out any further work, but to await the development of risk reduction measures. Conclusion (ii): There is at present no need for further information and/or testing and for risk reduction measures beyond those which are being applied already. For the aquatic compartment this conclusion applies to the use in mordant dyeing and to production (two Bites only). For sediment this conclusion applies to use in mordant dyeing. For waste water treatment plants, this conclusion applies to production, wood preservative application, anodising and mordant dyeing. For the terrestrial compartment, this conclusion applies to production and to mordant dyeing. This conclusion also applies to all areas for the air compartment and for indirect exposure though the fish-based food chain. Conclusion (iii) There is a need for limning the risks; risk reduction measures which are already being applied shall be taken into account. This conclusion applies to all areas for the aquatic, and terrestrial compartments, with the exception of mordant dyeing (both compartments) and production (terrestrial only, although the conclusion only applies to one production site for the aquatic). It also applies to waste water treatment plants for all areas, with the exception of production, wood preservative application, anodising and mordant dyeing. Human health Human health (toxicity) Occupational exposure Conclusion (i) There is a need for further information and/or testing. Conclusion (i) is reached for repeated dose toxicity to the respiratory tract and the kidney. It is not possible to formally calculate an MOS for these effects since no NOAELs have been identified. Hence it is not possible to assess risk under contemporary working conditions. Further exposure-response information for respiratory tract and kidney effects is required. Conclusion (ii) There is at present no need for further information and/or testing and no need for risk reduction measures beyond those which are being applied already. Conclusion (ii) is reached for acute toxicity for full shift exposures since MOS values indicate there is no cause for concern. Conclusion (iii) There is a need for limning the risks; risk reduction measures which are already being applied shall be taken into account. In view of the genotoxic and carcinogenic properties of these Cr(VI) compounds, there are concerns for all exposure scenarios. In addition, there are concerns for acute toxicity as a result of short-term peak exposures, skin and eye irritation, respiratory tract sensory irritation, skin sensitisation, occupational asthma and reproductive toxicity (fertility and developmental toxicity). Conclusion (iii) is reached for these endpoints. Consumer assessment Conclusion (ii) There is at present no need for further information and/or testing and no need for risk reduction measures beyond those which are being applied already. Conclusion (ii) is reached for all endpoints other than mutagenicity and carcinogenicity for the handling of CCA treated wood, both for adults and for children exposed via wooden playing structures. Conclusion (iii) There is a need for limiting the risks; risk reduction measures which are already being applied shall be taken into account. Conclusion (iii) is reached for mutagenicity and carcinogenicity because no threshold below which there would be no risk to human health can be identified for these endpoints. However, it is noted that exposure levels are very low. No formal risk characterisation has been conducted for consumer exposure to wet CCA treated wood. In the UK, the supply of wood not fully dried following CCA treatment is prohibited as a condition of approval under the Control of Pesticides Regulations (1986). Similar controls may already exist in all other Member States. However, if specific controls were not available in each Member State, then there would be concerns for all relevant human health endpoints Indirect exposure via the environment Conclusions are presented for both local and regional scenarios together. Conclusion (ii) There is at present no need for further information and/or testing and no need for risk reduction measures beyond those which are being applied already. Conclusion (ii) is reached for all endpoints other than mutagenicity and carcinogenicity. Conclusion (iii) There is a need for limiting the risks; risk reduction measures which are already being applied shall be taken into account. Conclusion (iii) is reached for mutagenicity and carcinogenicity because no threshold below which there would be no risk to human health can be identified for these endpoints. However, it is noted that exposure levels are very low. Combined exposure The combination of consumer exposure with indirect exposure via the environment does not produce significantly higher total exposures than those calculated for the separate individual contributions and therefore conclusion (ii) or, where appropriate, conclusion (iii) also applies to combined exposure. Human Health (physico-chemical properties) Given the level of control in manufacture and use the risks from physico-chemical properties are small. Conclusion (ii) There is at present no need for further information and/or testing and no need for risk reduction measures beyond those which are being applied already."
1238483,Anonymous 2004,Toxicological profile for Strontium,,Toxicological profile for Strontium Abs: 
1238482,Anonymous 2001,Zinc Chromates,"A TLV-TWA of 0.01 mg/m3, as chromium (Cr), is recommended for occupational exposure to zinc chromates to minimize the potential for respiratory cancers that have been amply and consistently demonstrated in epidemiologic studies of workers and in experimental animal bioassays. Based on the unequivocal carcinogenicity data, an A1, Confirmed Human Carcinogen, notation is designated for zinc chromates. As for any substance classified as an A1 carcinogen, work exposure by all routes should be carefully controlled to levels as low as possible below the TLV. Sufficient data were not available to recommend Skin or SEN notations or a TLV-STEL.","Zinc Chromates Abs: A TLV-TWA of 0.01 mg/m3, as chromium (Cr), is recommended for occupational exposure to zinc chromates to minimize the potential for respiratory cancers that have been amply and consistently demonstrated in epidemiologic studies of workers and in experimental animal bioassays. Based on the unequivocal carcinogenicity data, an A1, Confirmed Human Carcinogen, notation is designated for zinc chromates. As for any substance classified as an A1 carcinogen, work exposure by all routes should be carefully controlled to levels as low as possible below the TLV. Sufficient data were not available to recommend Skin or SEN notations or a TLV-STEL."
1238481,Anonymous 1997,Chromium,"Elemental chromium (Cr) does not occur in nature, but is present in ores, primarily chromite (FeOCr2O3) (Hamilton and Wetterhahn, 1988). Only two of the several oxidation states of chromium, Cr(III) and Cr(VI), are reviewed in this report based on their predominance and stability in the ambient environment and their toxicity in humans and animals. Chromium plays a role in glucose and cholesterol metabolism and is thus an essential element to man and animals (Schroeder et al., 1962). Non-occupational exposure to the metal occurs via the ingestion of chromium-containing food and water, whereas occupational exposure occurs via inhalation (Langard, 1982; Pedersen, 1982). Workers in the chromate industry have been exposed to estimated chromium levels of 10-50 ug/m3 for Cr(III) and 5-1000 ug/m3 for Cr(VI); however, improvements in the newer chrome-plating plants have reduced the Cr(VI) concentrations 10- to 40-fold (Stern, 1982). Chromium(III) is poorly absorbed, regardless of the route of exposure, whereas chromium(VI) is more readily absorbed (Hamilton and Wetterhahn, 1988). Humans and animals localize chromium in the lung, liver, kidney, spleen, adrenals, plasma, bone marrow, and red blood cells (RBC) (Langard, 1982; ATSDR, 1989; Bragt and van Dura, 1983; Hamilton and Wetterhahn, 1988). There is no evidence that chromium is biotransformed, but Cr(VI) does undergo enzymatic reduction, resulting in the formation of reactive intermediates and Cr(III) (Hamilton and Wetterhahn, 1988). The main routes for the excretion of chromium are via the kidneys/urine and the bile/feces (Guthrie, 1982; Langard, 1982). Animal studies show that Cr(VI) is generally more toxic than Cr(III), but neither oxidation state is very toxic by the oral route. In long-term studies, rats were not adversely affected by ~1.9 g/kg/day of chromic oxide [Cr(III)] (diet), 2.4 mg/kg/day of Cr(III) as chromic chloride (drinking water), or 2.4 mg/kg/day of Cr(VI) as potassium dichromate (drinking water) (Ivankovic and Preussmann, 1975; MacKenzie et al., 1958). The respiratory and dermal toxicity of chromium are well-documented. Workers exposed to chromium have developed nasal irritation (at <0.01 mg/m3, acute exposure), nasal ulcers, perforation of the nasal septum (at about 2 ?g/m3, subchronic or chronic exposure) (Hamilton and Wetterhahn, 1988; ATSDR, 1989; Lindberg and Hedenstierna, 1983) and hypersensitivity reactions and ""chrome holes"" of the skin (Pedersen, 1982; Burrows, 1983; U.S Air Force, 1990). Among the general population, contact dermatitis has been associated with the use of bleaches and detergents (Love, 1983). Compounds of both Cr(VI) and Cr(III) have induced developmental effects in experimental animals that include neural tube defects, malformations, and fetal deaths (Iijima et al., 1983; Danielsson et al., 1982; Matsumoto et al., 1976). The subchronic and chronic oral RfD value is 1 mg/kg/day for Cr(III). The subchronic and chronic oral RfD for Cr (VI) are 0.02 and 0.005 mg/kg/day, respectively (U.S. EPA, 1991a,b; 1992). The subchronic and chronic oral RfD values for Cr(VI) and Cr(III) are derived from no-observed-adverse-effect levels (NOAELs) of 1.47 g/kg Cr(III)/day and 25 ppm of potassium dichromate (Cr[VI]) in drinking water, respectively (Ivankovic and Preussmann, 1975; MacKenzie et al., 1958). The inhalation RfC values for both Cr(III) and Cr(VI) are currently under review by an EPA workgroup. The inhalation of chromium compounds has been associated with the development of cancer in workers in the chromate industry. The relative risk for developing lung cancer has been calculated to be as much as 30 times that of controls (Hayes, 1982; Leonard and Lauwerys, 1980; Langard, 1983). There is also evidence for an increased risk of developing nasal, pharyngeal, and gastrointestinal carcinomas (Hamilton and Wetterhahn, 1988). Quantitative epidemiological data were obtained by Mancuso and Hueper (1951), who observed an increase in deaths (18.2%; p<0.01) from respiratory cancer among chromate workers compared with 1.2% deaths among controls. In a follow-up study, conducted when more than 50% of the cohort had died, the observed incidence for lung cancer deaths had increased to approximately 60% (Mancuso, 1975). The workers were exposed to 1-8 mg/m3/year total chromium. Mancuso (1975) observed a dose response for total chromium exposure and attributed the lung cancer deaths to exposure to insoluble [Cr(III)], soluble [Cr(VI)], and total chromium. The results of inhalation studies in animals have been equivocal or negative (Nettesheim et al., 1971; Glaser et al, 1986; Baetjer et al., 1959; Steffee and Baetjer, 1965). Based on sufficient evidence for humans and animals, Cr(VI) has been placed in the EPA weight-of-evidence classification A, human carcinogen (U.S. EPA, 1991a). For inhalation exposure, the unit risk value is 1.2E-2 (ug/m3)-1 and the slope factor is 4.1E+01 (mg/kg/day)-1 (U.S. EPA, 1991a).","Chromium Abs: Elemental chromium (Cr) does not occur in nature, but is present in ores, primarily chromite (FeOCr2O3) (Hamilton and Wetterhahn, 1988). Only two of the several oxidation states of chromium, Cr(III) and Cr(VI), are reviewed in this report based on their predominance and stability in the ambient environment and their toxicity in humans and animals. Chromium plays a role in glucose and cholesterol metabolism and is thus an essential element to man and animals (Schroeder et al., 1962). Non-occupational exposure to the metal occurs via the ingestion of chromium-containing food and water, whereas occupational exposure occurs via inhalation (Langard, 1982; Pedersen, 1982). Workers in the chromate industry have been exposed to estimated chromium levels of 10-50 ug/m3 for Cr(III) and 5-1000 ug/m3 for Cr(VI); however, improvements in the newer chrome-plating plants have reduced the Cr(VI) concentrations 10- to 40-fold (Stern, 1982). Chromium(III) is poorly absorbed, regardless of the route of exposure, whereas chromium(VI) is more readily absorbed (Hamilton and Wetterhahn, 1988). Humans and animals localize chromium in the lung, liver, kidney, spleen, adrenals, plasma, bone marrow, and red blood cells (RBC) (Langard, 1982; ATSDR, 1989; Bragt and van Dura, 1983; Hamilton and Wetterhahn, 1988). There is no evidence that chromium is biotransformed, but Cr(VI) does undergo enzymatic reduction, resulting in the formation of reactive intermediates and Cr(III) (Hamilton and Wetterhahn, 1988). The main routes for the excretion of chromium are via the kidneys/urine and the bile/feces (Guthrie, 1982; Langard, 1982). Animal studies show that Cr(VI) is generally more toxic than Cr(III), but neither oxidation state is very toxic by the oral route. In long-term studies, rats were not adversely affected by ~1.9 g/kg/day of chromic oxide [Cr(III)] (diet), 2.4 mg/kg/day of Cr(III) as chromic chloride (drinking water), or 2.4 mg/kg/day of Cr(VI) as potassium dichromate (drinking water) (Ivankovic and Preussmann, 1975; MacKenzie et al., 1958). The respiratory and dermal toxicity of chromium are well-documented. Workers exposed to chromium have developed nasal irritation (at <0.01 mg/m3, acute exposure), nasal ulcers, perforation of the nasal septum (at about 2 ?g/m3, subchronic or chronic exposure) (Hamilton and Wetterhahn, 1988; ATSDR, 1989; Lindberg and Hedenstierna, 1983) and hypersensitivity reactions and ""chrome holes"" of the skin (Pedersen, 1982; Burrows, 1983; U.S Air Force, 1990). Among the general population, contact dermatitis has been associated with the use of bleaches and detergents (Love, 1983). Compounds of both Cr(VI) and Cr(III) have induced developmental effects in experimental animals that include neural tube defects, malformations, and fetal deaths (Iijima et al., 1983; Danielsson et al., 1982; Matsumoto et al., 1976). The subchronic and chronic oral RfD value is 1 mg/kg/day for Cr(III). The subchronic and chronic oral RfD for Cr (VI) are 0.02 and 0.005 mg/kg/day, respectively (U.S. EPA, 1991a,b; 1992). The subchronic and chronic oral RfD values for Cr(VI) and Cr(III) are derived from no-observed-adverse-effect levels (NOAELs) of 1.47 g/kg Cr(III)/day and 25 ppm of potassium dichromate (Cr[VI]) in drinking water, respectively (Ivankovic and Preussmann, 1975; MacKenzie et al., 1958). The inhalation RfC values for both Cr(III) and Cr(VI) are currently under review by an EPA workgroup. The inhalation of chromium compounds has been associated with the development of cancer in workers in the chromate industry. The relative risk for developing lung cancer has been calculated to be as much as 30 times that of controls (Hayes, 1982; Leonard and Lauwerys, 1980; Langard, 1983). There is also evidence for an increased risk of developing nasal, pharyngeal, and gastrointestinal carcinomas (Hamilton and Wetterhahn, 1988). Quantitative epidemiological data were obtained by Mancuso and Hueper (1951), who observed an increase in deaths (18.2%; p<0.01) from respiratory cancer among chromate workers compared with 1.2% deaths among controls. In a follow-up study, conducted when more than 50% of the cohort had died, the observed incidence for lung cancer deaths had increased to approximately 60% (Mancuso, 1975). The workers were exposed to 1-8 mg/m3/year total chromium. Mancuso (1975) observed a dose response for total chromium exposure and attributed the lung cancer deaths to exposure to insoluble [Cr(III)], soluble [Cr(VI)], and total chromium. The results of inhalation studies in animals have been equivocal or negative (Nettesheim et al., 1971; Glaser et al, 1986; Baetjer et al., 1959; Steffee and Baetjer, 1965). Based on sufficient evidence for humans and animals, Cr(VI) has been placed in the EPA weight-of-evidence classification A, human carcinogen (U.S. EPA, 1991a). For inhalation exposure, the unit risk value is 1.2E-2 (ug/m3)-1 and the slope factor is 4.1E+01 (mg/kg/day)-1 (U.S. EPA, 1991a)."
1238480,Anonymous 2006,Inorganic Lead and Lead compounds,"Evaluation. There is limited evidence in humans for the carcinogenicity of inorganic lead compounds. There is inadequate evidence in humans for the carcinogenicity of organic lead compounds. There is sufficient evidence in experimental animals for the carcinogenicity of inorganic lead compounds. There is sufficient evidence in experimental animals for the carcinogenicity of lead acetate, lead subacetate, lead chromate, and lead phosphate. There is inadequate evidence in experimental animals for the carcinogenicity of lead oxide and lead arsenate. There is inadequate evidence in experimental animals for the carcinogenicity of organic lead compounds. There is inadequate evidence in experimental animals for the carcinogenicity of tetra-ethyl lead. There is inadequate evidence in experimental animals for the carcinogenicity of lead powder. Overall evaluation. Inorganic lead compounds are probably carcinogenic to humans (Group 2A). Organic lead compounds are not classifiable as to their carcinogenicity to humans (Group 3). The Working Group noted that organic lead compounds are metabolized, at least in part, to ionic lead both in humans and animals. To the extent that ionic lead, generated from organic lead, is present in the body, it will be expected to exert the toxicities associated with inorganic lead.","Inorganic Lead and Lead compounds Abs: Evaluation. There is limited evidence in humans for the carcinogenicity of inorganic lead compounds. There is inadequate evidence in humans for the carcinogenicity of organic lead compounds. There is sufficient evidence in experimental animals for the carcinogenicity of inorganic lead compounds. There is sufficient evidence in experimental animals for the carcinogenicity of lead acetate, lead subacetate, lead chromate, and lead phosphate. There is inadequate evidence in experimental animals for the carcinogenicity of lead oxide and lead arsenate. There is inadequate evidence in experimental animals for the carcinogenicity of organic lead compounds. There is inadequate evidence in experimental animals for the carcinogenicity of tetra-ethyl lead. There is inadequate evidence in experimental animals for the carcinogenicity of lead powder. Overall evaluation. Inorganic lead compounds are probably carcinogenic to humans (Group 2A). Organic lead compounds are not classifiable as to their carcinogenicity to humans (Group 3). The Working Group noted that organic lead compounds are metabolized, at least in part, to ionic lead both in humans and animals. To the extent that ionic lead, generated from organic lead, is present in the body, it will be expected to exert the toxicities associated with inorganic lead."
1238479,standards 2005,Scientific basis for Swedish occupational standards XXVI. Consensus report for Inorganic Lead,"Conclusions. The critical effects of occupational exposure to lead are judged to be its effects on fetuses and breast-fed babies. There are several studies reporting inhibited growth and effects on the central nervous system in groups of children with average blood lead values (pregnant women/fetuses/babies) in the range 0.1 - 0.5 umol/1. It is not clear, however, whether the effects on the central nervous system are due primarily to the mother's exposure. It should be remembered that lead accumulates in bone and is liberated during pregnancy and lactation, meaning that the lead exposure of the mother earlier in life is also relevant to the risk. In the Swedish population blood lead levels are about 0.2 umol/1 for men and about 0.15 umol/1 for women. Effects in fetuses and breast-fed babies may exist around these levels. Effects on blood pressure are reported in large population studies, with a marginal increase at average blood lead levels of about 0.4 umol/l. An increase of this nature may mean some increase in risk of stroke and heart disease. Effects on kidneys, nervous system and endocrine systems, as well as DNA damage, have been reported in occupationally exposed groups with average blood lead levels of 1.5 umol/1. Effects on hemoglobin concentration, immune system and sperm quality have been reported in groups with average blood lead values around 2 [umol/l. Lead is carcinogenic to experimental animals, but there is only limited evidence that it is carcinogenic to humans. There is no simple relationship between levels of lead in air and in blood, and it is therefore not possible to give an air lead concentration for the critical effects.","Scientific basis for Swedish occupational standards XXVI. Consensus report for Inorganic Lead Abs: Conclusions. The critical effects of occupational exposure to lead are judged to be its effects on fetuses and breast-fed babies. There are several studies reporting inhibited growth and effects on the central nervous system in groups of children with average blood lead values (pregnant women/fetuses/babies) in the range 0.1 - 0.5 umol/1. It is not clear, however, whether the effects on the central nervous system are due primarily to the mother's exposure. It should be remembered that lead accumulates in bone and is liberated during pregnancy and lactation, meaning that the lead exposure of the mother earlier in life is also relevant to the risk. In the Swedish population blood lead levels are about 0.2 umol/1 for men and about 0.15 umol/1 for women. Effects in fetuses and breast-fed babies may exist around these levels. Effects on blood pressure are reported in large population studies, with a marginal increase at average blood lead levels of about 0.4 umol/l. An increase of this nature may mean some increase in risk of stroke and heart disease. Effects on kidneys, nervous system and endocrine systems, as well as DNA damage, have been reported in occupationally exposed groups with average blood lead levels of 1.5 umol/1. Effects on hemoglobin concentration, immune system and sperm quality have been reported in groups with average blood lead values around 2 [umol/l. Lead is carcinogenic to experimental animals, but there is only limited evidence that it is carcinogenic to humans. There is no simple relationship between levels of lead in air and in blood, and it is therefore not possible to give an air lead concentration for the critical effects."
1238478,Radding and  Furst 1980,A review of metals and carcinogenicity,"PESTAB. Information on the carcinogenicity of metals and metal compounds is reviewed. Epidemiologic studies conducted through the use of past company records are considered. Results of animal tests, and tests on the interaction of metals with various tissues, are presented. Lead acetate and lead chromate have been found to be potent carcinogens in mice and rats. Possible synergistic effects between lead and arsenic or a nitrosamine compound were suggested from carcinogenicity studies with lead arsenate and sodium arsenate. The use of a carcinogenicity index is also considered.","A review of metals and carcinogenicity Abs: PESTAB. Information on the carcinogenicity of metals and metal compounds is reviewed. Epidemiologic studies conducted through the use of past company records are considered. Results of animal tests, and tests on the interaction of metals with various tissues, are presented. Lead acetate and lead chromate have been found to be potent carcinogens in mice and rats. Possible synergistic effects between lead and arsenic or a nitrosamine compound were suggested from carcinogenicity studies with lead arsenate and sodium arsenate. The use of a carcinogenicity index is also considered."
1238476,Gromiec 1976,Determination of pentachlorophenol and its esters in air,"PESTAB. A method is presented for determining pentachlorophenol fatty acid ester concentrations in air. The air to be sampled is passed through a glass filter and esters are extracted from the filter with ether. The ether extract is placed into an evaporator and, after the solvent is removed, the dry residue is treated with a mixture of concentrated sulfuric acid and potassium bichromate. The decomposition of the PCP esters results in free chlorine release. The amount of chlorine released is determined with methyl orange. This method is non-specific. In the presence of pentachlorophenol in air, the sum of PCP and its esters is determined. A specific method for the determination of PCP in the presence of its esters is elaborated. PCP reacts with safranine O in alkaline solution, forming a pink complexon compound which is extracted with chloroform and measured spectrophotometrically. The PCP ester concentration is calculated from the difference in the above two concentrations. This method allows the determination of the concentration of any PCP ester or the sum of a mixture of esters, but the identification or separation of individual esters is not possible. The limit of determination is 0.033 mg/m3 of air for both PCP and its esters.","Determination of pentachlorophenol and its esters in air Abs: PESTAB. A method is presented for determining pentachlorophenol fatty acid ester concentrations in air. The air to be sampled is passed through a glass filter and esters are extracted from the filter with ether. The ether extract is placed into an evaporator and, after the solvent is removed, the dry residue is treated with a mixture of concentrated sulfuric acid and potassium bichromate. The decomposition of the PCP esters results in free chlorine release. The amount of chlorine released is determined with methyl orange. This method is non-specific. In the presence of pentachlorophenol in air, the sum of PCP and its esters is determined. A specific method for the determination of PCP in the presence of its esters is elaborated. PCP reacts with safranine O in alkaline solution, forming a pink complexon compound which is extracted with chloroform and measured spectrophotometrically. The PCP ester concentration is calculated from the difference in the above two concentrations. This method allows the determination of the concentration of any PCP ester or the sum of a mixture of esters, but the identification or separation of individual esters is not possible. The limit of determination is 0.033 mg/m3 of air for both PCP and its esters."
1238475,Cochrane et al. 1975,Structural elucidation of the chlordene isomer constituents of technical chlordane,"PESTAB. The technical chlordane constitutents designated alpha-, beta-, and gamma-chlordene are isomers of chlordene (C10H6Cl6). These isomers are formed via the rearrangement of chlordene by the action of Cl2 or free-radical initiating agents, and they no longer possess the cyclodiene-type structure. Elucidation of these isomeric structures involved various chemical derivatization reactions. Oxidation with chromic oxide yielded ketones and epoxides while reduction with Zn?HOAc or CrCl2 produced mono- and didechlorinated homologs. Photoisomers, in which the two original ClC=CCl bonds had been cross-linked, resulted from their unsensitized UV irradiation. Spectral confirmation of structure was obtained by 1H NMR and gas chromatography-mass spectrometry (GC-MS) studies. It is postulated that alpha-chlordene is 1,2,3,5,7,8- hexachloro- 1,3a,4,5,6,6a - hexahydro- 1,4-ethenopentalene (III) and beta-chlordene is 2,3,3a,4,5,7-hexachloro- 3a,6,7,7a-tetrahydro- 1,6-methano- 1H- indene (XIII), with gamma-chlordene (XI) being the 2,3,3a,4,5,8-hexachloro isomer of beta-chlordene. (Author abstract by permission)","Structural elucidation of the chlordene isomer constituents of technical chlordane Abs: PESTAB. The technical chlordane constitutents designated alpha-, beta-, and gamma-chlordene are isomers of chlordene (C10H6Cl6). These isomers are formed via the rearrangement of chlordene by the action of Cl2 or free-radical initiating agents, and they no longer possess the cyclodiene-type structure. Elucidation of these isomeric structures involved various chemical derivatization reactions. Oxidation with chromic oxide yielded ketones and epoxides while reduction with Zn?HOAc or CrCl2 produced mono- and didechlorinated homologs. Photoisomers, in which the two original ClC=CCl bonds had been cross-linked, resulted from their unsensitized UV irradiation. Spectral confirmation of structure was obtained by 1H NMR and gas chromatography-mass spectrometry (GC-MS) studies. It is postulated that alpha-chlordene is 1,2,3,5,7,8- hexachloro- 1,3a,4,5,6,6a - hexahydro- 1,4-ethenopentalene (III) and beta-chlordene is 2,3,3a,4,5,7-hexachloro- 3a,6,7,7a-tetrahydro- 1,6-methano- 1H- indene (XIII), with gamma-chlordene (XI) being the 2,3,3a,4,5,8-hexachloro isomer of beta-chlordene. (Author abstract by permission)"
1238474,Kuteev and  Zharkikh 1974,"Use of colorimetric methods for determining chlorophos, benzophosphate, and methylnitrophos in objects of a forest biocenosis","PESTAB. Colorimetric methods for the determination of trichlorfon, benzophosphate, and methylnitrophos in objects of sylvan biocenoses, and analyses of grass, leaves, soil, and water for the above pesticides are described by these methods. After extraction with sulfated ether and distilled water, trichlorfon was determined with pyridine after sulfuric acid and potassium dichromate were added. Investigation of grass and oak leaves from a forest area treated with trichlorfon at a rate of 1.3 kg/ha from aircraft revealed that the decomposition of this pesticide begins during the first days. Similar investigations showed that 60% of benzophosphate are decomposed in oak leaves, grass, and soil in two weeks after application. Benzophosphate was determined by measuring the optical density of the copper complex of diethyldithiophosphoric acid, the hydrolysis product of this compound. Methylnitrophos was determined by incubating plant samples with acetylcholinesterase. Oak leaves and grass contained no residues of methylnitrophos two weeks after spraying.","Use of colorimetric methods for determining chlorophos, benzophosphate, and methylnitrophos in objects of a forest biocenosis Abs: PESTAB. Colorimetric methods for the determination of trichlorfon, benzophosphate, and methylnitrophos in objects of sylvan biocenoses, and analyses of grass, leaves, soil, and water for the above pesticides are described by these methods. After extraction with sulfated ether and distilled water, trichlorfon was determined with pyridine after sulfuric acid and potassium dichromate were added. Investigation of grass and oak leaves from a forest area treated with trichlorfon at a rate of 1.3 kg/ha from aircraft revealed that the decomposition of this pesticide begins during the first days. Similar investigations showed that 60% of benzophosphate are decomposed in oak leaves, grass, and soil in two weeks after application. Benzophosphate was determined by measuring the optical density of the copper complex of diethyldithiophosphoric acid, the hydrolysis product of this compound. Methylnitrophos was determined by incubating plant samples with acetylcholinesterase. Oak leaves and grass contained no residues of methylnitrophos two weeks after spraying."
1238473,Sutherland 1974,Toxic effects of preserved timber,"PESTAB. In a Letter-to-the-Editor, veterinarians are asked to report any instances of adverse effects in cows or horses that have licked or chewed preserved timber. Tanalized timber has been treated with a preserving solution containing copper sulfate, potassium dichromate, and arsenious acid, all of which are toxic. Cases of animal injury due to treated timber have recently been reported form Sweden and Ireland, but no information was yet available from the United Kingdom.","Toxic effects of preserved timber Abs: PESTAB. In a Letter-to-the-Editor, veterinarians are asked to report any instances of adverse effects in cows or horses that have licked or chewed preserved timber. Tanalized timber has been treated with a preserving solution containing copper sulfate, potassium dichromate, and arsenious acid, all of which are toxic. Cases of animal injury due to treated timber have recently been reported form Sweden and Ireland, but no information was yet available from the United Kingdom."
1238472,YuV 1973,Determination of dinil in the air,"PESTAB (3 references) (Russian) jA colorimetric method for the determination of dinil in the air is described. Air is sampled through an absorber containing nitrating mixture (potassium nitrate with concentrated sulfuric acid). Then, benzene homologs are oxidized by means of potassium dichromate, after which extraction is done with toluene, and the extract is cleaned up with 1% sodium carbonate solution. The extract, containing nitro derivatives of dinil, and meta-dinitrobenzene, is combined with acetone, acetic acid, and 1% sodium sulfate solution for the obtainment of a colored solution suitable for colorimetric determination of dinil. s","Determination of dinil in the air Abs: PESTAB (3 references) (Russian) jA colorimetric method for the determination of dinil in the air is described. Air is sampled through an absorber containing nitrating mixture (potassium nitrate with concentrated sulfuric acid). Then, benzene homologs are oxidized by means of potassium dichromate, after which extraction is done with toluene, and the extract is cleaned up with 1% sodium carbonate solution. The extract, containing nitro derivatives of dinil, and meta-dinitrobenzene, is combined with acetone, acetic acid, and 1% sodium sulfate solution for the obtainment of a colored solution suitable for colorimetric determination of dinil. s"
1238471,Hughes 1970,"Tolerance of striped bass, Morone saxatilis (Walbaum), larvae and fingerlings to nine chemicals used in pond culture","PESTAB Nine chemicals were tested for toxicity to one week old larvae and one month old fingerling striped bass, Morone saxatilis (Walbaum). Higher concentrations of Karmex (diuron), potassium dichromate, potassium permanganate, and butyl ester of 2,4-D were required to kill fingerlings than larvae, yet fingerlings were more sensitive than larvae to parathion, methyl parathion, HTH, copper sulfate, or Dylox (trichlorfon). Copper sulfate, potassium permanganate, diuron, butyl ester of 2,4-D, HTH and parathion had 96-hr LC50s of 1 ppm or lower in larvae or fingerlings.","Tolerance of striped bass, Morone saxatilis (Walbaum), larvae and fingerlings to nine chemicals used in pond culture Abs: PESTAB Nine chemicals were tested for toxicity to one week old larvae and one month old fingerling striped bass, Morone saxatilis (Walbaum). Higher concentrations of Karmex (diuron), potassium dichromate, potassium permanganate, and butyl ester of 2,4-D were required to kill fingerlings than larvae, yet fingerlings were more sensitive than larvae to parathion, methyl parathion, HTH, copper sulfate, or Dylox (trichlorfon). Copper sulfate, potassium permanganate, diuron, butyl ester of 2,4-D, HTH and parathion had 96-hr LC50s of 1 ppm or lower in larvae or fingerlings."
1238464,Palacio et al. 1997,Contact Allergens and Sodium Lauryl Sulphate Upregulate Vascular Endothelial Growth Factor in Normal Keratinocytes,"The effects of contact allergens and sodium-lauryl-sulfate (151213) (SLS) on the release of vascular endothelial growth factor (VEGF) in normal human keratinocytes were examined, and the role of hydrocortisone assessed. Cells obtained from eight donors were cultured and stimulated with subtoxic concentrations of nickel-sulfate (7786814) (NiSO4), cobalt-chloride (7646799) (CoCl2), potassium-dichromate (7778509) (K2Cr2O7), dinitrosulfobenzene (DNSB), paraphenylenediamine (106503) (pPD), and SLS for 24 to 72 hours. Cell cultures were also treated with hydrocortisone (50237) or NiSO4 plus hydrocortisone. Following exposures, trypan-blue was used to determine cell viability and cell counts. An enzyme linked immunosorbent assay was used to measure the VEGF levels in culture supernatants. The metal salts induced significant, dose dependent increases in the level of VEGF released by the keratinocytes. VEGF concentrations in the culture supernatant rose fivefold in cultures stimulated with NiSO4 and CoCl2 and fourfold in cultures stimulated with K2Cr2O7. DNSB and pPD increased VEGF concentrations in the culture supernatant by twofold and threefold, respectively. These effects were noted for stimulation times of 24, 48, and 72 hours. VEGF levels were elevated by almost fivefold in cultures stimulated with the irritant SLS for 24 or 48 hours. At a concentration of 2 micrograms per milliliter, hydrocortisone reduced the level of VEGF release in keratinocytes by approximately 30%. Hydrocortisone inhibited the stimulatory effect of NiSO4 in a significant, dose dependent, and time dependent manner. The authors conclude that contact allergens and irritants stimulate the release of VEGF in keratinocytes in-vitro, which may result in the microvascular hyperpermeability of contact and irritant dermatitis.","Contact Allergens and Sodium Lauryl Sulphate Upregulate Vascular Endothelial Growth Factor in Normal Keratinocytes Abs: The effects of contact allergens and sodium-lauryl-sulfate (151213) (SLS) on the release of vascular endothelial growth factor (VEGF) in normal human keratinocytes were examined, and the role of hydrocortisone assessed. Cells obtained from eight donors were cultured and stimulated with subtoxic concentrations of nickel-sulfate (7786814) (NiSO4), cobalt-chloride (7646799) (CoCl2), potassium-dichromate (7778509) (K2Cr2O7), dinitrosulfobenzene (DNSB), paraphenylenediamine (106503) (pPD), and SLS for 24 to 72 hours. Cell cultures were also treated with hydrocortisone (50237) or NiSO4 plus hydrocortisone. Following exposures, trypan-blue was used to determine cell viability and cell counts. An enzyme linked immunosorbent assay was used to measure the VEGF levels in culture supernatants. The metal salts induced significant, dose dependent increases in the level of VEGF released by the keratinocytes. VEGF concentrations in the culture supernatant rose fivefold in cultures stimulated with NiSO4 and CoCl2 and fourfold in cultures stimulated with K2Cr2O7. DNSB and pPD increased VEGF concentrations in the culture supernatant by twofold and threefold, respectively. These effects were noted for stimulation times of 24, 48, and 72 hours. VEGF levels were elevated by almost fivefold in cultures stimulated with the irritant SLS for 24 or 48 hours. At a concentration of 2 micrograms per milliliter, hydrocortisone reduced the level of VEGF release in keratinocytes by approximately 30%. Hydrocortisone inhibited the stimulatory effect of NiSO4 in a significant, dose dependent, and time dependent manner. The authors conclude that contact allergens and irritants stimulate the release of VEGF in keratinocytes in-vitro, which may result in the microvascular hyperpermeability of contact and irritant dermatitis."
1238458,Ginsburg et al. 1996,A Novel Approach to the Assessment of Toxicity of Hexachlorocyclohexane (Lindane) and of Certain Organic Solvents: Killing of Cells in Culture and the Release of Arachidonate by Synergism among H2O2 Membrane,"A new approach was developed for the assessment of the toxicity of the chlorinated pesticide hexachlorocyclohexane (58899) and the organic solvents methanol (67561) and n-butanol (71363) using endothelial cells in culture. Rat pulmonary endothelial cells labeled with arachidonic-acid labeled with tritium or chromium-51 labeled sodium-chromate were treated with xenobiotics combined with glucose-oxidase generated hydrogen-peroxide, phospholipase, streptolysin-S, diethyldithiocarbamate, sodium-nitroprusside, histone, and trypsin. This resulted in the synergistic cell killing and release of arachidonic-acid. The finding indicates that subtoxic amounts of xenobiotics failed to kill the cells but became highly cytolytic when combined with the various mixtures of agonists. Catalase, manganese2+, and soybean trypsin inhibitor strongly inhibited the cytotoxicity and release of membrane lipids. In infectious and inflammatory sites where phagocyte and tissue derived proinflammatory agonists are generated in large amounts, the synergism concept of cellular toxicity may be relevant. This report suggested that the synergism phenomenon, whereby mixtures of pesticides with oxidants and with additional membrane damaging agents amplify cellular damage in-vitro, might help evaluate the relative toxicity of xenobiotics.","A Novel Approach to the Assessment of Toxicity of Hexachlorocyclohexane (Lindane) and of Certain Organic Solvents: Killing of Cells in Culture and the Release of Arachidonate by Synergism among H2O2 Membrane Abs: A new approach was developed for the assessment of the toxicity of the chlorinated pesticide hexachlorocyclohexane (58899) and the organic solvents methanol (67561) and n-butanol (71363) using endothelial cells in culture. Rat pulmonary endothelial cells labeled with arachidonic-acid labeled with tritium or chromium-51 labeled sodium-chromate were treated with xenobiotics combined with glucose-oxidase generated hydrogen-peroxide, phospholipase, streptolysin-S, diethyldithiocarbamate, sodium-nitroprusside, histone, and trypsin. This resulted in the synergistic cell killing and release of arachidonic-acid. The finding indicates that subtoxic amounts of xenobiotics failed to kill the cells but became highly cytolytic when combined with the various mixtures of agonists. Catalase, manganese2+, and soybean trypsin inhibitor strongly inhibited the cytotoxicity and release of membrane lipids. In infectious and inflammatory sites where phagocyte and tissue derived proinflammatory agonists are generated in large amounts, the synergism concept of cellular toxicity may be relevant. This report suggested that the synergism phenomenon, whereby mixtures of pesticides with oxidants and with additional membrane damaging agents amplify cellular damage in-vitro, might help evaluate the relative toxicity of xenobiotics."
1238449,Stearns and  Wetterhahn 1997,Intermediates Produced in the Reaction of Chromium(VI) with Dehydroascorbate Cause Single-Strand Breaks in Plasmid DNA,"A study of the genotoxicity of reactive intermediates produced by the reaction of hexavalent chromium (7440473) (Cr) with dehydroascorbate (DHA) was conducted. Potassium-dichromate (7778509) at 20 millimolar (mM) was reacted with 100mM DHA in sodium-acetate buffer, pH 3.8, in the presence or absence of 20mM divalent manganese (Mn2+) for up to 90 minutes (min). The reaction mixtures were monitored by ultraviolet/visible spectrophotometry and electron paramagnetic (EPR) spectroscopy to detect Cr species. Cr6+ reacted with DHA to produce Cr5+ and Cr4+ species. The maximum formation of Cr5+ occurred after about 20min. When the mixtures resulting from the reaction of 20mM potassium-dichromate with DHA were diluted to produce a potassium-dichromate concentration of 3.0mM after 50min of reaction, the EPR and ultraviolet/visible spectral signals increased in intensity. This was interpreted as 20mM Cr6+ reacting with DHA to produce a dimeric Cr5+ species, which after dilution to 3.0mM dissociated to form a Cr5+ monomer. In the presence of Mn2+, the Cr4+ species were catalytically disproportionated to Cr5+ and Cr3+ species. The ability of the various reactive species to induce DNA damage was assessed by incubating the Cr6+ reaction mixtures with plasmid pBR322 DNA at pH 3.8 or 5.8 in the presence or absence of Mn2+ for up to 90min and determining the extent of DNA single strand breakage by a gel electrophoresis based relaxation assay. The reaction mixtures at both pHs cause a significant increase in DNA single strand breaks (SSBs). Induction of SSBs was greater at pH 3.8 than at 5.8. Cr4+ was judged to be the major species producing SSBs at pH 3.8 because the time course for the damage did not match that for formation of Cr5+, and Mn2+ (a Cr4+ scavenger) inhibited formation of the SSBs. At pH 5.8, induction of DNA SSBs was attributed to Cr5+ since the time course for SSB induction was similar to that for formation of Cr5+. The authors conclude that induction of DNA SSBs in different Cr6+ systems is probably not caused by a single chromium species. The reactivity of the various chromium species depends on the specific experimental conditions.","Intermediates Produced in the Reaction of Chromium(VI) with Dehydroascorbate Cause Single-Strand Breaks in Plasmid DNA Abs: A study of the genotoxicity of reactive intermediates produced by the reaction of hexavalent chromium (7440473) (Cr) with dehydroascorbate (DHA) was conducted. Potassium-dichromate (7778509) at 20 millimolar (mM) was reacted with 100mM DHA in sodium-acetate buffer, pH 3.8, in the presence or absence of 20mM divalent manganese (Mn2+) for up to 90 minutes (min). The reaction mixtures were monitored by ultraviolet/visible spectrophotometry and electron paramagnetic (EPR) spectroscopy to detect Cr species. Cr6+ reacted with DHA to produce Cr5+ and Cr4+ species. The maximum formation of Cr5+ occurred after about 20min. When the mixtures resulting from the reaction of 20mM potassium-dichromate with DHA were diluted to produce a potassium-dichromate concentration of 3.0mM after 50min of reaction, the EPR and ultraviolet/visible spectral signals increased in intensity. This was interpreted as 20mM Cr6+ reacting with DHA to produce a dimeric Cr5+ species, which after dilution to 3.0mM dissociated to form a Cr5+ monomer. In the presence of Mn2+, the Cr4+ species were catalytically disproportionated to Cr5+ and Cr3+ species. The ability of the various reactive species to induce DNA damage was assessed by incubating the Cr6+ reaction mixtures with plasmid pBR322 DNA at pH 3.8 or 5.8 in the presence or absence of Mn2+ for up to 90min and determining the extent of DNA single strand breakage by a gel electrophoresis based relaxation assay. The reaction mixtures at both pHs cause a significant increase in DNA single strand breaks (SSBs). Induction of SSBs was greater at pH 3.8 than at 5.8. Cr4+ was judged to be the major species producing SSBs at pH 3.8 because the time course for the damage did not match that for formation of Cr5+, and Mn2+ (a Cr4+ scavenger) inhibited formation of the SSBs. At pH 5.8, induction of DNA SSBs was attributed to Cr5+ since the time course for SSB induction was similar to that for formation of Cr5+. The authors conclude that induction of DNA SSBs in different Cr6+ systems is probably not caused by a single chromium species. The reactivity of the various chromium species depends on the specific experimental conditions."
1238447,Liu and  Dixon 1996,Induction of mutagenic DNA damage by chromium(VI) and glutathione,"Certain chromium (Cr) compounds are known to be carcinogenic in humans and mutagenic in cell culture. However, the mechanism of Cr mutagenesis is not well understood. It appears that intracellular reduction of Cr by agents such as glutathione plays a role in the induction of DNA damage. We have used a simian virus 40-based shuttle vector to investigate the relationship between chromium-induced DNA damage and Cr mutagenicity. The treatment of the plasmid pZ189 with Cr(VI) plus glutathione (GSH) induced DNA strand breaks and reduced the plasmid biological activity, whereas Cr(III) treatment with or without GSH did not give rise to such DNA damage. When Cr(VI)/GSH- or Cr(III)/GSH-treated pZ189 was replicated in mammalian cells, a dose-dependent increase in mutant frequency was observed with Cr(VI)/GSH-treated pZ189, but not with Cr(III)/GSH-treated plasmid. About 43% of the mutants from Cr(VI)/GSH-treated pZ189 were deletion mutants. The remainder were base substitution mutants, mostly GC ? AT transitions and GC ? TA transversions. This pattern of mutagenesis is similar to that observed with other agents that cause oxidative DNA damage such as ionizing radiation and H2O2. These results support the hypothesis that Cr mutagenesis can be induced by the generation of reactive oxygen intermediates during the reduction of Cr(VI) by glutathione.","Induction of mutagenic DNA damage by chromium(VI) and glutathione Abs: Certain chromium (Cr) compounds are known to be carcinogenic in humans and mutagenic in cell culture. However, the mechanism of Cr mutagenesis is not well understood. It appears that intracellular reduction of Cr by agents such as glutathione plays a role in the induction of DNA damage. We have used a simian virus 40-based shuttle vector to investigate the relationship between chromium-induced DNA damage and Cr mutagenicity. The treatment of the plasmid pZ189 with Cr(VI) plus glutathione (GSH) induced DNA strand breaks and reduced the plasmid biological activity, whereas Cr(III) treatment with or without GSH did not give rise to such DNA damage. When Cr(VI)/GSH- or Cr(III)/GSH-treated pZ189 was replicated in mammalian cells, a dose-dependent increase in mutant frequency was observed with Cr(VI)/GSH-treated pZ189, but not with Cr(III)/GSH-treated plasmid. About 43% of the mutants from Cr(VI)/GSH-treated pZ189 were deletion mutants. The remainder were base substitution mutants, mostly GC ? AT transitions and GC ? TA transversions. This pattern of mutagenesis is similar to that observed with other agents that cause oxidative DNA damage such as ionizing radiation and H2O2. These results support the hypothesis that Cr mutagenesis can be induced by the generation of reactive oxygen intermediates during the reduction of Cr(VI) by glutathione."
1238444,Iwasaki and  Ojima 1997,Design of a Circular Slot Hood for a Local Exhaust System and Its Application to a Mixing Process for Fine Particles and Organic Solvents,"A circular slot hood design for a local exhaust system to be used in manufacturing processes was described, and the airflow characteristics of the hood, relative to slot sizes, were discussed. A profile of centerline velocities in a circular slot hood was presented. Optimum conditions for airflow characteristics and slot size were determined by installing the circular slot hood in a mixing process for fine particles and organic solvents. The concentrations of total dust, chromium-oxide (1308389) and organic solvents such as toluene (108883), methyl-ethyl-ketone (78933), and methyl-isobutyl-ketone (108101) were measured before and during ventilation. Centerline velocity was observed to be independent of airflow rate, and the relationship between centerline velocity and the ratio of centerline distance to slot width was independent of slot size. The optimum values for airflow rate into the exhaust system, and the average slot face velocity were, respectively, 20.14 cubic meters/minute and 8.55 meters/second. The operation of the local exhaust system with the circular slot hood significantly reduced the concentration of total dust, chromium-oxide, and the three organic solvents to levels below the threshold limit values. The authors conclude that a circular slot hood can be effectively used in manufacturing processes involving reactors, mixing vessels, and hoppers with round openings.","Design of a Circular Slot Hood for a Local Exhaust System and Its Application to a Mixing Process for Fine Particles and Organic Solvents Abs: A circular slot hood design for a local exhaust system to be used in manufacturing processes was described, and the airflow characteristics of the hood, relative to slot sizes, were discussed. A profile of centerline velocities in a circular slot hood was presented. Optimum conditions for airflow characteristics and slot size were determined by installing the circular slot hood in a mixing process for fine particles and organic solvents. The concentrations of total dust, chromium-oxide (1308389) and organic solvents such as toluene (108883), methyl-ethyl-ketone (78933), and methyl-isobutyl-ketone (108101) were measured before and during ventilation. Centerline velocity was observed to be independent of airflow rate, and the relationship between centerline velocity and the ratio of centerline distance to slot width was independent of slot size. The optimum values for airflow rate into the exhaust system, and the average slot face velocity were, respectively, 20.14 cubic meters/minute and 8.55 meters/second. The operation of the local exhaust system with the circular slot hood significantly reduced the concentration of total dust, chromium-oxide, and the three organic solvents to levels below the threshold limit values. The authors conclude that a circular slot hood can be effectively used in manufacturing processes involving reactors, mixing vessels, and hoppers with round openings."
1238439,Akyol et al. 1996,Evaluation of the Patch Test Results with Standard Antigens in Various Types of Eczema,"The data generated from patch testing with standard antigens in patients with eczema were assessed. Standard patch tests were performed on 318 patients diagnosed with eczema. A total of 112 patients reacted positively to at least one antigen, of whom 71.4% were females. The greatest proportion of positive reactions, 39.2%, was observed in the 20 to 29 year old age group. The allergens which most frequently induced positive reactions included nickel-sulfate (7786814), cobalt-chloride (7646799), and potassium-dichromate (7778509). In fact, 38.3% of the positive reactions recorded were reactions to nickel-sulfate. The body regions most often afflicted with eczema were the hands, face, and trunk. Lesions localized to the hands accounted for 67.8% of all breakouts. The occupations with the greatest numbers of positive reactions included office workers, 26.7% of all reactions, and housewives, 24.1% of all reactions. The authors conclude that differences in sex, age, localization, and occupation impact individual sensitization to the various allergens examined via patch testing with the standard series.","Evaluation of the Patch Test Results with Standard Antigens in Various Types of Eczema Abs: The data generated from patch testing with standard antigens in patients with eczema were assessed. Standard patch tests were performed on 318 patients diagnosed with eczema. A total of 112 patients reacted positively to at least one antigen, of whom 71.4% were females. The greatest proportion of positive reactions, 39.2%, was observed in the 20 to 29 year old age group. The allergens which most frequently induced positive reactions included nickel-sulfate (7786814), cobalt-chloride (7646799), and potassium-dichromate (7778509). In fact, 38.3% of the positive reactions recorded were reactions to nickel-sulfate. The body regions most often afflicted with eczema were the hands, face, and trunk. Lesions localized to the hands accounted for 67.8% of all breakouts. The occupations with the greatest numbers of positive reactions included office workers, 26.7% of all reactions, and housewives, 24.1% of all reactions. The authors conclude that differences in sex, age, localization, and occupation impact individual sensitization to the various allergens examined via patch testing with the standard series."
1238436,Junaid et al. 1996,Embryo and fetotoxicity of chromium in pregestationally exposed mice,"The role of pregestationally accumulated body chromium (7440473) (CR) in embryo and fetal development was assessed in Swiss-albino female mice. Four groups of 15 mice each were given 0, 250, 500, and 750 parts per million (ppm) potassium dichromate for 20 days, and then mated. Animals were sacrificed and blood, placentas, and fetuses were collected on the 19th day of gestation. An absence of implantation in the uterine horns occurred in the highest CR group. In the 500ppm group, a significant increase in the number of resorptions (37%) occurred compared with controls. A significant decrease in fetal weight, placental weight, and crown rump length, and an increase in post implantation loss occurred in the 250ppm CR group compared with controls. No dead fetuses occurred in any of the CR treated groups. Fetuses in the 500ppm CR group had high numbers of subdermal hemorrhagic patches and kinky, short tails compared to controls and the 250ppm CR group. Significantly reduced ossification in the caudal, parietal and interparietal bones occurred in fetuses of the 500ppm CR group. Placental CR concentration increased in a dose dependent manner in the 250 and 500ppm CR groups compared with controls. The CR treated animals showed a higher blood CR concentration compared with controls, with the 750ppm group having the highest CR concentrations. However, blood CR concentrations of the 250 and 500ppm CR groups did not differ from one another. The authors conclude that the placenta may act as a barrier to retard the passage of CR from mother to fetus, safeguarding fetal development and growth.","Embryo and fetotoxicity of chromium in pregestationally exposed mice Abs: The role of pregestationally accumulated body chromium (7440473) (CR) in embryo and fetal development was assessed in Swiss-albino female mice. Four groups of 15 mice each were given 0, 250, 500, and 750 parts per million (ppm) potassium dichromate for 20 days, and then mated. Animals were sacrificed and blood, placentas, and fetuses were collected on the 19th day of gestation. An absence of implantation in the uterine horns occurred in the highest CR group. In the 500ppm group, a significant increase in the number of resorptions (37%) occurred compared with controls. A significant decrease in fetal weight, placental weight, and crown rump length, and an increase in post implantation loss occurred in the 250ppm CR group compared with controls. No dead fetuses occurred in any of the CR treated groups. Fetuses in the 500ppm CR group had high numbers of subdermal hemorrhagic patches and kinky, short tails compared to controls and the 250ppm CR group. Significantly reduced ossification in the caudal, parietal and interparietal bones occurred in fetuses of the 500ppm CR group. Placental CR concentration increased in a dose dependent manner in the 250 and 500ppm CR groups compared with controls. The CR treated animals showed a higher blood CR concentration compared with controls, with the 750ppm group having the highest CR concentrations. However, blood CR concentrations of the 250 and 500ppm CR groups did not differ from one another. The authors conclude that the placenta may act as a barrier to retard the passage of CR from mother to fetus, safeguarding fetal development and growth."
1238429,Gueniche et al. 1994,Effect of Various Metals on Intercellular Adhesion Molecule-1 Expression and Tumour Necrosis Factor Alpha Production by Normal Human Keratinocytes,"The ability of nickel (7440020), cobalt (7440484), chromium (7440473), and cadmium (7440439) to induce intercellular adhesion molecule-1 (ICAM-1), tumor necrosis factor alpha (TNF-alpha) and Hsp72 protein in human keratinocytes was investigated. Normal human keratinocytes were cultured and treated with 10 micrograms/milliliter (microg/ml) nickel-sulfate (7786814), 12microg/ml cobalt-chloride (7646799), 2microg/ml potassium-dichromate (7778509), 1.5microg/ml cadmium-sulfate (10124364), 100microg/ml lipopolysaccharide (LPS), 10 International Units interferon-gamma, or 5microg/ml TNF-alpha. Quantification by flow cytometry analysis determined that 88.2% of the cells treated with TNF-alpha and 94.0% of cells treated with nickel expressed ICAM-1. Less than 1% expression was observed in control and other treated cells. Immunocytochemistry detected TNF-alpha production in cells cultured with LPS and all metals. Significant release of TNF-alpha was detected by enzyme linked immunoassay in supernatants of cells treated with nickel, cobalt and chromium, but was less than induced by LPS. Indirect immunofluorescence showed positive Hsp72 staining in 45% to 65% of cells treated with nickel, cobalt, chromium or cadmium. No evidence of Hsp72 induction by LPS was detected. The authors conclude that activation of keratinocytes by nickel, cobalt, chromium and cadmium involves the production of TNF-alpha and expression of Hsp72, and that the induction of ICAM-1 by nickel may be involved in allergic contact dermatitis.","Effect of Various Metals on Intercellular Adhesion Molecule-1 Expression and Tumour Necrosis Factor Alpha Production by Normal Human Keratinocytes Abs: The ability of nickel (7440020), cobalt (7440484), chromium (7440473), and cadmium (7440439) to induce intercellular adhesion molecule-1 (ICAM-1), tumor necrosis factor alpha (TNF-alpha) and Hsp72 protein in human keratinocytes was investigated. Normal human keratinocytes were cultured and treated with 10 micrograms/milliliter (microg/ml) nickel-sulfate (7786814), 12microg/ml cobalt-chloride (7646799), 2microg/ml potassium-dichromate (7778509), 1.5microg/ml cadmium-sulfate (10124364), 100microg/ml lipopolysaccharide (LPS), 10 International Units interferon-gamma, or 5microg/ml TNF-alpha. Quantification by flow cytometry analysis determined that 88.2% of the cells treated with TNF-alpha and 94.0% of cells treated with nickel expressed ICAM-1. Less than 1% expression was observed in control and other treated cells. Immunocytochemistry detected TNF-alpha production in cells cultured with LPS and all metals. Significant release of TNF-alpha was detected by enzyme linked immunoassay in supernatants of cells treated with nickel, cobalt and chromium, but was less than induced by LPS. Indirect immunofluorescence showed positive Hsp72 staining in 45% to 65% of cells treated with nickel, cobalt, chromium or cadmium. No evidence of Hsp72 induction by LPS was detected. The authors conclude that activation of keratinocytes by nickel, cobalt, chromium and cadmium involves the production of TNF-alpha and expression of Hsp72, and that the induction of ICAM-1 by nickel may be involved in allergic contact dermatitis."
1238427,Milanowski et al. 1994,Stimulation of Alveolar Macrophage Interleukin-1 Production by Organic Dust-Derived Products,"A study was done to evaluate the effects of various microbial agents, which have been associated with organic dusts, on macrophage interleukin-1 (IL-1) production. Alveolar macrophages (AMs) were obtained from English-short-hair-guinea-pigs. Freshly isolated AMs at a concentration of 10(7) cells/milliliter were incubated with chromium-51 (Cr51) labeled sodium-chromate. Following exposure to most microbial extracts, the release of Cr51 was concentration dependent. At concentrations of less than 1 microgram/milliliter (microg/ml) the release of Cr51 was no different from that observed in control cells. Concentrations higher than 100microg/ml caused significant leakage of Cr51 within 16 hours. IL-1 production assay results indicated that IL-1 production occurred only following the stimulation of AMs by extracts of Enterobacter-agglomerans and Thermoactinomyces-vulgaris and endotoxin from E-agglomerans. The release of IL-1 was dependent on the dose with maximal effects being obtained at concentrations of 10microg/ml. The findings indicated that endotoxin preparations from E-agglomerans and the extract of E-agglomerans were more potent than Escherichia-coli 055:B5 endotoxin. Higher levels of IL-1 were noted when supernates were tested at a 1:2 dilution, suggesting that inhibitors may have been found in the undiluted supernates. The authors conclude that IL-1 production may be important in the pathogenesis of organic dust induced lung disease.","Stimulation of Alveolar Macrophage Interleukin-1 Production by Organic Dust-Derived Products Abs: A study was done to evaluate the effects of various microbial agents, which have been associated with organic dusts, on macrophage interleukin-1 (IL-1) production. Alveolar macrophages (AMs) were obtained from English-short-hair-guinea-pigs. Freshly isolated AMs at a concentration of 10(7) cells/milliliter were incubated with chromium-51 (Cr51) labeled sodium-chromate. Following exposure to most microbial extracts, the release of Cr51 was concentration dependent. At concentrations of less than 1 microgram/milliliter (microg/ml) the release of Cr51 was no different from that observed in control cells. Concentrations higher than 100microg/ml caused significant leakage of Cr51 within 16 hours. IL-1 production assay results indicated that IL-1 production occurred only following the stimulation of AMs by extracts of Enterobacter-agglomerans and Thermoactinomyces-vulgaris and endotoxin from E-agglomerans. The release of IL-1 was dependent on the dose with maximal effects being obtained at concentrations of 10microg/ml. The findings indicated that endotoxin preparations from E-agglomerans and the extract of E-agglomerans were more potent than Escherichia-coli 055:B5 endotoxin. Higher levels of IL-1 were noted when supernates were tested at a 1:2 dilution, suggesting that inhibitors may have been found in the undiluted supernates. The authors conclude that IL-1 production may be important in the pathogenesis of organic dust induced lung disease."
1238424,Spiewak et al. 1995,A Double Case Report: Clinically Different Occupational Dermatoses Resulting from Identical Exposure to Work Environment at a Photographic Laboratory,"This report considered two cases of employees working in a photographic laboratory who developed dermatoses differing in morphology and clinical course. The first case was a 19 year old woman working at the manual and automated processing of black/white and color films and film printing. She had continuous contact with 2-naphthylamine (91598), amidole (137097), mercury-chloride (7487947), diazolethylaniline, potassium-dichromate (7778509), fenidone, formaldehyde (50000), hydroquinone (123319), metol (55550), sodium-methylodisulfate, hydroxylamine-sulfate (10039540), and mercury (7439976) salts. Two months after the introduction of a new processing technology based on Tetenal photochemicals, skin lesions appeared, which subsequently spread to the upper half of her body, involving the upper extremities, chest and abdomen. She was diagnosed with allergic contact dermatitis due to sensitization to multiple photochemicals. The second case involved a 17 year old patient who had worked for 1 year in the same photographic laboratory with identical occupational exposures. Her diagnosis was lichenoid contact dermatitis provoked by multiple photochemicals. The authors conclude that, aside from the irritating and allergenic properties of photochemicals, individual susceptibility also is important in etiopathogenesis and the determination of a clinical picture of dermatoses caused by these chemicals.","A Double Case Report: Clinically Different Occupational Dermatoses Resulting from Identical Exposure to Work Environment at a Photographic Laboratory Abs: This report considered two cases of employees working in a photographic laboratory who developed dermatoses differing in morphology and clinical course. The first case was a 19 year old woman working at the manual and automated processing of black/white and color films and film printing. She had continuous contact with 2-naphthylamine (91598), amidole (137097), mercury-chloride (7487947), diazolethylaniline, potassium-dichromate (7778509), fenidone, formaldehyde (50000), hydroquinone (123319), metol (55550), sodium-methylodisulfate, hydroxylamine-sulfate (10039540), and mercury (7439976) salts. Two months after the introduction of a new processing technology based on Tetenal photochemicals, skin lesions appeared, which subsequently spread to the upper half of her body, involving the upper extremities, chest and abdomen. She was diagnosed with allergic contact dermatitis due to sensitization to multiple photochemicals. The second case involved a 17 year old patient who had worked for 1 year in the same photographic laboratory with identical occupational exposures. Her diagnosis was lichenoid contact dermatitis provoked by multiple photochemicals. The authors conclude that, aside from the irritating and allergenic properties of photochemicals, individual susceptibility also is important in etiopathogenesis and the determination of a clinical picture of dermatoses caused by these chemicals."
1238423,Lundberg 1994,Scientific Basis for Swedish Occupational Standards XV,"Consensus reports approved by the Swedish National Institute of Occupational Health (NIOH) for ethylene-glycol-monopropyl-ether (2807309), ethylene-glycol-monopropylether-acetate (20706256), hexachloroethane (67721), 13 inorganic and organic esters of stearic-acid, hexylene-glycol (107415), barium (7440393A), barium-carbonate (513779), barium-sulfate (7727437), barium-chromate (10294403), strontium (7440246), strontium-chloride (10476854), strontium-chromate (7789062), dicyclopentadiene (77736), N,N-dimethylacetamide (127195), indium (7440746) and inorganic indium compounds, o-chloro-benzylidene-malonitrile (2698411), and thioglycolic-acid (68111) were presented. The reports were published by the Criteria Group of the NIOH between 1993 and 1994 and were intended to provide a basis for discussing Swedish occupational limits. The data in the reports were obtained from searches of the published literature, databases such as Toxline, Medline, and NIOSHTIC, and criteria documents published by the World Health Organization, NIOSH, the Nordic Expert Group, and other organizations. Each report provided information on the physicochemical properties, biokinetics, metabolism, excretion, toxicological properties, carcinogenicity, mutagenicity, teratogenicity, dose response or dose effect relationships, and toxic effects relevant for human exposure of the compounds.","Scientific Basis for Swedish Occupational Standards XV Abs: Consensus reports approved by the Swedish National Institute of Occupational Health (NIOH) for ethylene-glycol-monopropyl-ether (2807309), ethylene-glycol-monopropylether-acetate (20706256), hexachloroethane (67721), 13 inorganic and organic esters of stearic-acid, hexylene-glycol (107415), barium (7440393A), barium-carbonate (513779), barium-sulfate (7727437), barium-chromate (10294403), strontium (7440246), strontium-chloride (10476854), strontium-chromate (7789062), dicyclopentadiene (77736), N,N-dimethylacetamide (127195), indium (7440746) and inorganic indium compounds, o-chloro-benzylidene-malonitrile (2698411), and thioglycolic-acid (68111) were presented. The reports were published by the Criteria Group of the NIOH between 1993 and 1994 and were intended to provide a basis for discussing Swedish occupational limits. The data in the reports were obtained from searches of the published literature, databases such as Toxline, Medline, and NIOSHTIC, and criteria documents published by the World Health Organization, NIOSH, the Nordic Expert Group, and other organizations. Each report provided information on the physicochemical properties, biokinetics, metabolism, excretion, toxicological properties, carcinogenicity, mutagenicity, teratogenicity, dose response or dose effect relationships, and toxic effects relevant for human exposure of the compounds."
1238422,Rosina et al. 1995,Allergic Contact Dermatitis from Pleurotus Mushroom,"A case report of allergic contact dermatitis in a 55 year old male who had grown Pleurotus-ostreatus for 5 years was described. The cultivation of P-ostreatus, an edible mushroom species grown world wide, was briefly discussed. Previous allergic reactions of the respiratory system to the mushroom were cited, but none involving dermatitis were known. The patient suffered from red scaly vesicular lesions on the hands, which spread to the upper and lower limbs, face, and trunk. There was also a history of chromate dermatitis from the age of 20 which had cleared 10 years previously after leaving the construction industry. Allergic rhinitis had been diagnosed at 6 years of age with positive tests to Parietaria-officinalis. The patient's symptoms coincided with the harvest cycles of the mushrooms, especially in the advanced stage of maturation. Patch test conducted with the GIRDCA standard and agricultural series showed positive reactions to potassium-dichromate (7778509) and dinocap (39300453), a pesticide. Positive reactions were also seen to the lamellae, stem and spores of the mushroom. Immediate type allergy was excluded by negative open and prick tests. The authors conclude that the patient had allergic contact dermatitis to P-ostreatus, which may have been potentiated by previous exposure and allergic reaction to chromate.","Allergic Contact Dermatitis from Pleurotus Mushroom Abs: A case report of allergic contact dermatitis in a 55 year old male who had grown Pleurotus-ostreatus for 5 years was described. The cultivation of P-ostreatus, an edible mushroom species grown world wide, was briefly discussed. Previous allergic reactions of the respiratory system to the mushroom were cited, but none involving dermatitis were known. The patient suffered from red scaly vesicular lesions on the hands, which spread to the upper and lower limbs, face, and trunk. There was also a history of chromate dermatitis from the age of 20 which had cleared 10 years previously after leaving the construction industry. Allergic rhinitis had been diagnosed at 6 years of age with positive tests to Parietaria-officinalis. The patient's symptoms coincided with the harvest cycles of the mushrooms, especially in the advanced stage of maturation. Patch test conducted with the GIRDCA standard and agricultural series showed positive reactions to potassium-dichromate (7778509) and dinocap (39300453), a pesticide. Positive reactions were also seen to the lamellae, stem and spores of the mushroom. Immediate type allergy was excluded by negative open and prick tests. The authors conclude that the patient had allergic contact dermatitis to P-ostreatus, which may have been potentiated by previous exposure and allergic reaction to chromate."
1238416,Karwas 1995,Ammonia Complexation in the Analysis of Hexavalent Chromium in Fly Ash,"The interaction between ammonia (NH3) and chromate in the analysis of fly ash samples for hexavalent chromium (7440473) (Cr) was investigated through sample analysis, potentiometric titrations and spectroscopy. Using four digestion solutions, the amount of Cr4+ in fly ash samples was measured as 5.8 micrograms/gram (microg/g) fly ash with sodium-hydroxide, 3.9microg/g with ammonium-hydroxide, 8.7microg/g with carbonate buffer, and 6.9microg/g with ammonia buffer. Percent recovery in Cr4+ and Cr3+ spiked samples was determined. Potentiometric titration of NH3 with nitric-acid in the presence of chromate revealed two equivalence points corresponding to the protonation of NH3 and of an NH3/chromate complex. Titration of NH3 with nitric-acid in the absence of chromate yielded a single equivalence point, while similar titrations of potassium-dichromate showed no equivalence points. Titrations of solutions with constant NH3 concentrations showed a decrease in the equivalence point for NH3 and an increase in the equivalence point for chromate with increasing chromate concentration. Total equivalence remained constant, regardless of chromate concentration. Titrations in the presence of constant chromate but increasing NH3 concentrations showed the total equivalence increasing linearly with NH3 concentration. The chromate equivalence point remained constant. Results indicated that NH3 and chromate complex in a 1:1 ratio. No change was observed in the ultraviolet/visible spectra of chromate solutions with the addition of NH3. The author concludes that NH3 increases the accuracy of Cr4+ determinations by preventing the oxidation of Cr3+ and by complexing with Cr4+, thereby increasing recovery.","Ammonia Complexation in the Analysis of Hexavalent Chromium in Fly Ash Abs: The interaction between ammonia (NH3) and chromate in the analysis of fly ash samples for hexavalent chromium (7440473) (Cr) was investigated through sample analysis, potentiometric titrations and spectroscopy. Using four digestion solutions, the amount of Cr4+ in fly ash samples was measured as 5.8 micrograms/gram (microg/g) fly ash with sodium-hydroxide, 3.9microg/g with ammonium-hydroxide, 8.7microg/g with carbonate buffer, and 6.9microg/g with ammonia buffer. Percent recovery in Cr4+ and Cr3+ spiked samples was determined. Potentiometric titration of NH3 with nitric-acid in the presence of chromate revealed two equivalence points corresponding to the protonation of NH3 and of an NH3/chromate complex. Titration of NH3 with nitric-acid in the absence of chromate yielded a single equivalence point, while similar titrations of potassium-dichromate showed no equivalence points. Titrations of solutions with constant NH3 concentrations showed a decrease in the equivalence point for NH3 and an increase in the equivalence point for chromate with increasing chromate concentration. Total equivalence remained constant, regardless of chromate concentration. Titrations in the presence of constant chromate but increasing NH3 concentrations showed the total equivalence increasing linearly with NH3 concentration. The chromate equivalence point remained constant. Results indicated that NH3 and chromate complex in a 1:1 ratio. No change was observed in the ultraviolet/visible spectra of chromate solutions with the addition of NH3. The author concludes that NH3 increases the accuracy of Cr4+ determinations by preventing the oxidation of Cr3+ and by complexing with Cr4+, thereby increasing recovery."
1238412,Kiec-Swierczynska and  Szymczk 1995,The Effect of the Working Environment on Occupational Skin Disease Development in Workers Processing Rockwool,"A study was conducted on the incidence of metal allergy in a group of workers exposed to rockwool insulation and phenol-formaldehyde-resin. Workers from an insulation materials production facility were patch tested with an allergen set which included potassium-dichromate (7778509), nickel-sulfate (7786814), cobalt-chloride (7646799), and phenol-formaldehyde-resin and examined for evidence of dermatitis. Over 25% of the workers were found to have contact dermatitis and 9.6% had oil acne, compared with incidence rates of 3.4% and 0%, respectively, in unexposed referents. More females than males had dermatitis; however, over five times as many males were found to have oil acne. Overall, 7.3% of the workers were found to be sensitive to nickel, 6.9% to chromium (7440473), 5.0% to cobalt (7440484), 3.1% to formaldehyde (50000), and 1.5% to the phenol-formaldehyde-resin. Allergy accounted for 30 of the 65 cases of dermatitis seen in the workers. The incidence of dermatitis and allergy to nickel and cobalt in males and females and to chromium in males was significantly increased in the rockwool workers. The presence of chromium, nickel, and cobalt in the rockwool insulation material was confirmed by atomic absorption analysis.","The Effect of the Working Environment on Occupational Skin Disease Development in Workers Processing Rockwool Abs: A study was conducted on the incidence of metal allergy in a group of workers exposed to rockwool insulation and phenol-formaldehyde-resin. Workers from an insulation materials production facility were patch tested with an allergen set which included potassium-dichromate (7778509), nickel-sulfate (7786814), cobalt-chloride (7646799), and phenol-formaldehyde-resin and examined for evidence of dermatitis. Over 25% of the workers were found to have contact dermatitis and 9.6% had oil acne, compared with incidence rates of 3.4% and 0%, respectively, in unexposed referents. More females than males had dermatitis; however, over five times as many males were found to have oil acne. Overall, 7.3% of the workers were found to be sensitive to nickel, 6.9% to chromium (7440473), 5.0% to cobalt (7440484), 3.1% to formaldehyde (50000), and 1.5% to the phenol-formaldehyde-resin. Allergy accounted for 30 of the 65 cases of dermatitis seen in the workers. The incidence of dermatitis and allergy to nickel and cobalt in males and females and to chromium in males was significantly increased in the rockwool workers. The presence of chromium, nickel, and cobalt in the rockwool insulation material was confirmed by atomic absorption analysis."
1238411,Brawer et al. 1995,Uptake and Subcellular Distribution of 51Cr in Gomori-Positive Astrocytes in Primary Culture,"Astrocytes from neonatal Sprague-Dawley-rats were used to study the uptake and intracellular distribution of chromium (7440473) during Gomori inclusion formation. After 7 days in culture, the cells were dosed with chromium-51 in the form of sodium-chromate (7775113) with an activity of 3 microcuries/milliliter. Twenty four hours later, half of the cells were dosed with 0.1mg/ml cysteamine. Exposed and control cells were fixed and processed at 12, 24, and 72 hours following cysteamine treatment. Cells were then photographed and radioautographic grains were localized and counted. Astrocytes that had not been treated with cysteamine showed normal morphological characteristics. Controls showed little uptake of the radioautographically labeled chromate. Cells treated with cysteamine displayed progressive development of Gomori inclusions. Mitochondria exhibited dense granular matrices and loss of cristae. Cysteamine treated cells had four times as much radioautographic labeling as controls. The authors state that Gomori inclusion formation coincides with an increase in cellular permeability to chromium.","Uptake and Subcellular Distribution of 51Cr in Gomori-Positive Astrocytes in Primary Culture Abs: Astrocytes from neonatal Sprague-Dawley-rats were used to study the uptake and intracellular distribution of chromium (7440473) during Gomori inclusion formation. After 7 days in culture, the cells were dosed with chromium-51 in the form of sodium-chromate (7775113) with an activity of 3 microcuries/milliliter. Twenty four hours later, half of the cells were dosed with 0.1mg/ml cysteamine. Exposed and control cells were fixed and processed at 12, 24, and 72 hours following cysteamine treatment. Cells were then photographed and radioautographic grains were localized and counted. Astrocytes that had not been treated with cysteamine showed normal morphological characteristics. Controls showed little uptake of the radioautographically labeled chromate. Cells treated with cysteamine displayed progressive development of Gomori inclusions. Mitochondria exhibited dense granular matrices and loss of cristae. Cysteamine treated cells had four times as much radioautographic labeling as controls. The authors state that Gomori inclusion formation coincides with an increase in cellular permeability to chromium."
1238406,Roche 1995,Reducing Carcinogens in Public Schools: A Non-Regulatory Approach by a Regulatory Agency,"A pilot project which used information from the 1990 Right to Know (RTK) Survey to reduce public school staff potential exposure to carcinogens was conducted. A total of 318 school districts in New Jersey were identified which reported any of 10 selected carcinogens on the Survey. Of the 32 randomly selected school districts from the 318, 31 (97%) participated in a phone survey. The findings from this survey indicated the use of arsenic (7440382), arsenic-trioxide (1327533), asbestos (1332214), benzene (71432), lead-chromate (7758976), sodium-arsenate (7778430), and sodium-dichromate (10588019) in pure form for science or chemistry experiments or demonstrations. Asbestos was also used for roof patching or cement, benzene for drying leather, benzene in gasoline/fuel or in cleaners, lead-chromate (7758976) in paint for maintenance and in glazes for an art class, and sodium-dichromate in floorstripper. Employees potentially exposed included chemistry and science teachers and maintenance personnel. Following the study, 78% of the reported carcinogens in school districts that returned the follow up form were disposed of, used completely and not reordered, or were scheduled for disposal. The author concludes that both the enforcement of the New Jersey RTK Law and this project contributed to the reduction of exposure to carcinogens in the school districts.","Reducing Carcinogens in Public Schools: A Non-Regulatory Approach by a Regulatory Agency Abs: A pilot project which used information from the 1990 Right to Know (RTK) Survey to reduce public school staff potential exposure to carcinogens was conducted. A total of 318 school districts in New Jersey were identified which reported any of 10 selected carcinogens on the Survey. Of the 32 randomly selected school districts from the 318, 31 (97%) participated in a phone survey. The findings from this survey indicated the use of arsenic (7440382), arsenic-trioxide (1327533), asbestos (1332214), benzene (71432), lead-chromate (7758976), sodium-arsenate (7778430), and sodium-dichromate (10588019) in pure form for science or chemistry experiments or demonstrations. Asbestos was also used for roof patching or cement, benzene for drying leather, benzene in gasoline/fuel or in cleaners, lead-chromate (7758976) in paint for maintenance and in glazes for an art class, and sodium-dichromate in floorstripper. Employees potentially exposed included chemistry and science teachers and maintenance personnel. Following the study, 78% of the reported carcinogens in school districts that returned the follow up form were disposed of, used completely and not reordered, or were scheduled for disposal. The author concludes that both the enforcement of the New Jersey RTK Law and this project contributed to the reduction of exposure to carcinogens in the school districts."
1238401,Sugiyama 1994,Role of Paramagnetic Chromium in Chromium(VI)-Induced Damage in Cultured Mammalian Cells,"The relationship between paramagnetic chromium (7440473) (Cr) and Cr(VI) induced damage in cultured cells was ascertained. Incubation of Chinese-hamster-V-79 cells with sodium-chromate (7775113) resulted in Cr(V) and Cr(III) electron spin resonance signals. An increase in the chromate concentration or an increase in the time of incubation resulted in an increase in the formation of Cr(V) and Cr(III) complexes. The concentration of Cr(III) was 30 fold greater than Cr(V) in treated cells. After removal of extracellular chromate, the level of Cr(V) decreased rapidly while the Cr(III) level remained unchanged. The addition of alpha-tocopherol or ascorbic-acid reduced the Cr(V) levels. Riboflavin increased the Cr(V) levels and ascorbic-acid increased the Cr(III) levels. Single strand breaks and alkali labile sites induced by Cr were reduced by increasing the concentration of tocopherol or ascorbic-acid. Riboflavin enhanced the level of single strand breaks and alkali labile sites. Tocopherol or ascorbic-acid restored glutathione-reductase activity while riboflavin enhanced the inhibition of glutathione-reductase activity by chromate. Tocopherol suppressed the clastogenic and mutagenic effects of Cr, and riboflavin enhanced the effects. Tocopherol and riboflavin had no effect on DNA protein cross links induced by Cr but the levels were enhanced by ascorbic-acid. The uptake of chromium was unaffected by tocopherol or riboflavin and was accelerated by ascorbic-acid. Tocopherol and riboflavin reduced the cytotoxicity caused by chromate while ascorbic-acid enhanced cytotoxicity. The author concludes that paramagnetic chromium may play a role in the carcinogenicity of chromium(VI) compounds.","Role of Paramagnetic Chromium in Chromium(VI)-Induced Damage in Cultured Mammalian Cells Abs: The relationship between paramagnetic chromium (7440473) (Cr) and Cr(VI) induced damage in cultured cells was ascertained. Incubation of Chinese-hamster-V-79 cells with sodium-chromate (7775113) resulted in Cr(V) and Cr(III) electron spin resonance signals. An increase in the chromate concentration or an increase in the time of incubation resulted in an increase in the formation of Cr(V) and Cr(III) complexes. The concentration of Cr(III) was 30 fold greater than Cr(V) in treated cells. After removal of extracellular chromate, the level of Cr(V) decreased rapidly while the Cr(III) level remained unchanged. The addition of alpha-tocopherol or ascorbic-acid reduced the Cr(V) levels. Riboflavin increased the Cr(V) levels and ascorbic-acid increased the Cr(III) levels. Single strand breaks and alkali labile sites induced by Cr were reduced by increasing the concentration of tocopherol or ascorbic-acid. Riboflavin enhanced the level of single strand breaks and alkali labile sites. Tocopherol or ascorbic-acid restored glutathione-reductase activity while riboflavin enhanced the inhibition of glutathione-reductase activity by chromate. Tocopherol suppressed the clastogenic and mutagenic effects of Cr, and riboflavin enhanced the effects. Tocopherol and riboflavin had no effect on DNA protein cross links induced by Cr but the levels were enhanced by ascorbic-acid. The uptake of chromium was unaffected by tocopherol or riboflavin and was accelerated by ascorbic-acid. Tocopherol and riboflavin reduced the cytotoxicity caused by chromate while ascorbic-acid enhanced cytotoxicity. The author concludes that paramagnetic chromium may play a role in the carcinogenicity of chromium(VI) compounds."
1238400,Misra et al. 1994,Two pathways for chromium(VI)-induced DNA damage in 14 day chick embryos: Cr-DNA binding in liver and 8-oxo-2'-deoxyguanosine in red blood cells,"Previous studies have shown that chromium(VI) induced cell-specific types of DNA damage, i.e. DNA cross-links in liver and DNA strand breaks in red blood cells, in 14 day chick embryos. Direct and indirect pathways for chromium(VI)-mediated DNA damage, in the form of Cr-DNA binding and 8-oxo-2'-deoxyguanosine (8-oxo-dG) respectively, were examined in liver and red blood cells of 14 day chick embryos. Levels of hepatic Cr-DNA binding increased in a Cr(VI) dose-dependent manner. Cr-DNA binding in red blood cells was 10-fold lower than in liver, although the Cr-uptake in red blood cells was only 2-fold lower than in liver. The level of 8-oxo-dG formation in red blood cells increased at all Cr(VI) doses tested but peaked at 0.10 mmol Cr(VI)/kg, whereas no increase in 8-oxo-dG levels over background levels was observed in liver of Cr(VI)-treated embryos. The possible role of glutathione in modulating Cr(VI)-induced DNA damage was examined by using L-buthionine-R,S-sulfoximine (BSO) to deplete glutathione. No changes in glutathione levels were observed in either liver or red blood cells of embryos treated with Cr(VI) in the presence or absence of BSO pretreatment. Ascorbate levels in liver and red blood cells were not affected by treatment of embryos with chromium(VI), BSO or Cr(VI) and BSO. Depletion of glutathione by BSO resulted in a small increase of chromium uptake in liver of embryos treated with 0.050 and 0.10 mmol Cr(VI)/kg, but had no effect on hepatic chromium uptake at 0.20 mmol Cr(VI)/kg. BSO had no effect on chromium uptake in red blood cells. Depletion of glutathione had no effect on hepatic or red blood cells Cr-DNA binding in embryos treated with Cr(VI). However, depletion of glutathione significantly decreased the 8-oxo-dG levels in red blood cells at all Cr(VI) doses tested. Levels of 8-oxo-dG in liver of Cr(VI)-treated embryos remained at background in the presence or absence of BSO pretreatment. These results indicate that Cr(VI)-induced DNA damage in 14 day chick embryos is through a direct interaction of chromium with DNA in liver, but is through an indirect oxidative pathway in red blood cells. It appears that glutathione plays an important role in chromium(VI)-induced formation of 8-oxo-dG in red blood cells.","Two pathways for chromium(VI)-induced DNA damage in 14 day chick embryos: Cr-DNA binding in liver and 8-oxo-2'-deoxyguanosine in red blood cells Abs: Previous studies have shown that chromium(VI) induced cell-specific types of DNA damage, i.e. DNA cross-links in liver and DNA strand breaks in red blood cells, in 14 day chick embryos. Direct and indirect pathways for chromium(VI)-mediated DNA damage, in the form of Cr-DNA binding and 8-oxo-2'-deoxyguanosine (8-oxo-dG) respectively, were examined in liver and red blood cells of 14 day chick embryos. Levels of hepatic Cr-DNA binding increased in a Cr(VI) dose-dependent manner. Cr-DNA binding in red blood cells was 10-fold lower than in liver, although the Cr-uptake in red blood cells was only 2-fold lower than in liver. The level of 8-oxo-dG formation in red blood cells increased at all Cr(VI) doses tested but peaked at 0.10 mmol Cr(VI)/kg, whereas no increase in 8-oxo-dG levels over background levels was observed in liver of Cr(VI)-treated embryos. The possible role of glutathione in modulating Cr(VI)-induced DNA damage was examined by using L-buthionine-R,S-sulfoximine (BSO) to deplete glutathione. No changes in glutathione levels were observed in either liver or red blood cells of embryos treated with Cr(VI) in the presence or absence of BSO pretreatment. Ascorbate levels in liver and red blood cells were not affected by treatment of embryos with chromium(VI), BSO or Cr(VI) and BSO. Depletion of glutathione by BSO resulted in a small increase of chromium uptake in liver of embryos treated with 0.050 and 0.10 mmol Cr(VI)/kg, but had no effect on hepatic chromium uptake at 0.20 mmol Cr(VI)/kg. BSO had no effect on chromium uptake in red blood cells. Depletion of glutathione had no effect on hepatic or red blood cells Cr-DNA binding in embryos treated with Cr(VI). However, depletion of glutathione significantly decreased the 8-oxo-dG levels in red blood cells at all Cr(VI) doses tested. Levels of 8-oxo-dG in liver of Cr(VI)-treated embryos remained at background in the presence or absence of BSO pretreatment. These results indicate that Cr(VI)-induced DNA damage in 14 day chick embryos is through a direct interaction of chromium with DNA in liver, but is through an indirect oxidative pathway in red blood cells. It appears that glutathione plays an important role in chromium(VI)-induced formation of 8-oxo-dG in red blood cells."
1238398,Shi et al. 1994,Reaction of Cr(VI) with ascorbate and hydrogen peroxide generates hydroxyl radicals and causes DNA damage: Role of a Cr(IV)-mediated Fenton-Like reaction,"Biochemical processes involved in the generation of hydroxyl radicals from the reaction of chromium (7440473) with ascorbate (50817) and/or hydrogen-peroxide (7722841) (H2O2) were studied. Reaction of potassium-dichromate (7778509) with ascorbate resulted in the generation of chromium(V), chromium(IV), as well as alkyl and formyl radicals as determined by electron spin resonance. The addition of H2O2 resulted in the formation of hydroxyl radicals and increased amounts of chromium(V). The generation of hydroxyl radicals was confirmed using spin trapping competition studies. DNA double strand breaks were observed following incubation with chromium(VI) and H2O2, but not by either of these agents alone. A greater number of breaks was seen with the addition of ascorbate, while the addition of manganese (7439965) decreased the amount of DNA damage. Hydroxylation of 2'-deoxyguanine (dG) to form 8-hydroxy-2'-deoxyguanine was demonstrated in a mixture of dG, chromium(VI), ascorbate, and H2O2 using high performance liquid chromatography. The authors conclude that hydroxyl radicals are generated by a Fenton like reaction involving chromium(VI) and H2O2.","Reaction of Cr(VI) with ascorbate and hydrogen peroxide generates hydroxyl radicals and causes DNA damage: Role of a Cr(IV)-mediated Fenton-Like reaction Abs: Biochemical processes involved in the generation of hydroxyl radicals from the reaction of chromium (7440473) with ascorbate (50817) and/or hydrogen-peroxide (7722841) (H2O2) were studied. Reaction of potassium-dichromate (7778509) with ascorbate resulted in the generation of chromium(V), chromium(IV), as well as alkyl and formyl radicals as determined by electron spin resonance. The addition of H2O2 resulted in the formation of hydroxyl radicals and increased amounts of chromium(V). The generation of hydroxyl radicals was confirmed using spin trapping competition studies. DNA double strand breaks were observed following incubation with chromium(VI) and H2O2, but not by either of these agents alone. A greater number of breaks was seen with the addition of ascorbate, while the addition of manganese (7439965) decreased the amount of DNA damage. Hydroxylation of 2'-deoxyguanine (dG) to form 8-hydroxy-2'-deoxyguanine was demonstrated in a mixture of dG, chromium(VI), ascorbate, and H2O2 using high performance liquid chromatography. The authors conclude that hydroxyl radicals are generated by a Fenton like reaction involving chromium(VI) and H2O2."
1238386,Shi et al. 1994,"Enhanced Generation of Hydroxyl Radical and Sulfur Trioxide Anion Radical from Oxidation of Sodium Sulfite, Nickel(II) Sulfite, and Nickel Subsulfide in the Presence of Nickel(II) Complexes","Free radical generation during the autooxidation of sulfite with nickel (7440020) (Ni) added in either nonchelated or chelated form was investigated using electron spin resonance (ESR) spin trapping. ESR analysis demonstrated the generation of sulfite radical when a neutral solution of sodium-sulfite (7757837) (Na2SO3) reacted with air. When Ni was added, the intensity of the free radical spin adduct signal increased four fold and the addition of glycylglycylhistidine (GlyGlyHis) to the Nia2SO3 solution increased the signal 15 fold. The formation of free radicals reached saturation in 5 minutes. GlyGlyHis alone did not enhance the autooxidation of Na2SO3. Potassium-chromate (7789006) reacted with Na2SO3 to generate only sulfite radicals. The GlyGlyHis/Ni/Na2SO3 oxidation produced 65% sulfite radicals and 35% hydroxyl radicals. Formate added to the GlyGlyHis/Ni/Na2SO3 reaction resulted in the formation of carboxyl radicals suggesting hydroxyl radicals were produced in the initial reaction. Performing the GlyGlyHis/Ni/Na2SO3 reaction under argon reduced the ESR signal suggesting that the free radical generation required molecular oxygen. Desferoxamine and DTPA reduced radical formation and the two compounds decreased the enhancing effect of Ni on radical generation in the absence of GlyGlyHis. Albumin doubled the radical signal in the Ni/Na2SO3 oxidation. Nickel-sulfite (7757951) alone did not generate significant amounts of free radicals but the formation was enhanced by GlyGlyHis and consisted of sulfite and hydroxyl radicals. Nickel-subsulfide (12035722) (NI3S2) with GlyGlyHis and hydrogen-peroxide generated sulfite radicals. Ni with GlyGlyHis and H2O2 generated superoxide radicals. Ni3S2 with either GlyGlyHis or H2O2 did not generate free radicals.","Enhanced Generation of Hydroxyl Radical and Sulfur Trioxide Anion Radical from Oxidation of Sodium Sulfite, Nickel(II) Sulfite, and Nickel Subsulfide in the Presence of Nickel(II) Complexes Abs: Free radical generation during the autooxidation of sulfite with nickel (7440020) (Ni) added in either nonchelated or chelated form was investigated using electron spin resonance (ESR) spin trapping. ESR analysis demonstrated the generation of sulfite radical when a neutral solution of sodium-sulfite (7757837) (Na2SO3) reacted with air. When Ni was added, the intensity of the free radical spin adduct signal increased four fold and the addition of glycylglycylhistidine (GlyGlyHis) to the Nia2SO3 solution increased the signal 15 fold. The formation of free radicals reached saturation in 5 minutes. GlyGlyHis alone did not enhance the autooxidation of Na2SO3. Potassium-chromate (7789006) reacted with Na2SO3 to generate only sulfite radicals. The GlyGlyHis/Ni/Na2SO3 oxidation produced 65% sulfite radicals and 35% hydroxyl radicals. Formate added to the GlyGlyHis/Ni/Na2SO3 reaction resulted in the formation of carboxyl radicals suggesting hydroxyl radicals were produced in the initial reaction. Performing the GlyGlyHis/Ni/Na2SO3 reaction under argon reduced the ESR signal suggesting that the free radical generation required molecular oxygen. Desferoxamine and DTPA reduced radical formation and the two compounds decreased the enhancing effect of Ni on radical generation in the absence of GlyGlyHis. Albumin doubled the radical signal in the Ni/Na2SO3 oxidation. Nickel-sulfite (7757951) alone did not generate significant amounts of free radicals but the formation was enhanced by GlyGlyHis and consisted of sulfite and hydroxyl radicals. Nickel-subsulfide (12035722) (NI3S2) with GlyGlyHis and hydrogen-peroxide generated sulfite radicals. Ni with GlyGlyHis and H2O2 generated superoxide radicals. Ni3S2 with either GlyGlyHis or H2O2 did not generate free radicals."
1238385,S-O and  Sanner 1994,Increased Gap Junctional Intercellular Communication in Syrian Hamster Embryo Cells Treated with Oxidative Agents,"Compounds known or presumed to cause oxidative stress were studied for their effect on gap junction intercellular communication (GJIC) in the Syrian-hamster cell line, BPNi. The cyclic AMP (cAMP) system was also studied to determine if it was mediating the increase in GJIC. Hydrogen-peroxide (7722841) (H2O2), KBrO3 (7758012), menadione (58275) and benzoyl-peroxide (94360) induced a greater than 50% increase in GJIC after a 1 hour incubation. K2CrO4 (7789006) exposed cells reached a maximum increase in GJIC after 4 hours of treatment. The decrease in intercellular communication after removal of H2O2 followed a first order reaction. When cells were irradiated with ultraviolet light at a fluence of 600 kilojoules per square meter, there was an increase in GJIC. There was no increase in GJIC after BPNi cells were heat shocked at 43 to 47 degrees-C. Oxidative agents did not increase nonjunctional permeability which may have given an impression of increased GJIC. A 2 hour preincubation with the hydroxyl radical scavenger, dimethylsulfoxide (67685) (DMSO) had a protective effect against the increase in GJIC caused by 1 millimolar (mM) H2O2. DMSO had no effect at lower H2O2 concentrations or when a 1 minute preincubation was used. Inhibition of catalase by preincubation with amitrole (61825) did not increase the level of GJIC after exposure to H2O2. H2O2 at a concentration of 100 micromolar did not alter the 12-ortho-tetradecanoylphorbol-13-acetate (16561298) (TPA) induced decrease in GJIC. However, 1mM H2O2 still resulted in an increase in GJIC despite the continuous exposure to TPA. There was an increase in cAMP levels in 3-isobutyl-1-methylxanthine (28822584) (IBMX) treated cells and a concomitant 50% increase in GJIC. Similar results were obtained with 30 micromolar forskolin (66575299). There was no difference in cAMP levels in H2O2 exposed and control cells. Phosphodiesterase inhibitors increased cAMP levels eight fold while coexposure with H2O2 resulted in a four fold increase. Several protein kinase-A inhibitors inhibited the H2O2 induced increase in GJIC to varying degrees. The authors conclude that cAMP is not a probable mediator of the effects of oxidative agents on GJIC in BPNi cells.","Increased Gap Junctional Intercellular Communication in Syrian Hamster Embryo Cells Treated with Oxidative Agents Abs: Compounds known or presumed to cause oxidative stress were studied for their effect on gap junction intercellular communication (GJIC) in the Syrian-hamster cell line, BPNi. The cyclic AMP (cAMP) system was also studied to determine if it was mediating the increase in GJIC. Hydrogen-peroxide (7722841) (H2O2), KBrO3 (7758012), menadione (58275) and benzoyl-peroxide (94360) induced a greater than 50% increase in GJIC after a 1 hour incubation. K2CrO4 (7789006) exposed cells reached a maximum increase in GJIC after 4 hours of treatment. The decrease in intercellular communication after removal of H2O2 followed a first order reaction. When cells were irradiated with ultraviolet light at a fluence of 600 kilojoules per square meter, there was an increase in GJIC. There was no increase in GJIC after BPNi cells were heat shocked at 43 to 47 degrees-C. Oxidative agents did not increase nonjunctional permeability which may have given an impression of increased GJIC. A 2 hour preincubation with the hydroxyl radical scavenger, dimethylsulfoxide (67685) (DMSO) had a protective effect against the increase in GJIC caused by 1 millimolar (mM) H2O2. DMSO had no effect at lower H2O2 concentrations or when a 1 minute preincubation was used. Inhibition of catalase by preincubation with amitrole (61825) did not increase the level of GJIC after exposure to H2O2. H2O2 at a concentration of 100 micromolar did not alter the 12-ortho-tetradecanoylphorbol-13-acetate (16561298) (TPA) induced decrease in GJIC. However, 1mM H2O2 still resulted in an increase in GJIC despite the continuous exposure to TPA. There was an increase in cAMP levels in 3-isobutyl-1-methylxanthine (28822584) (IBMX) treated cells and a concomitant 50% increase in GJIC. Similar results were obtained with 30 micromolar forskolin (66575299). There was no difference in cAMP levels in H2O2 exposed and control cells. Phosphodiesterase inhibitors increased cAMP levels eight fold while coexposure with H2O2 resulted in a four fold increase. Several protein kinase-A inhibitors inhibited the H2O2 induced increase in GJIC to varying degrees. The authors conclude that cAMP is not a probable mediator of the effects of oxidative agents on GJIC in BPNi cells."
1238382,Wang et al. 1994,Chromium-Induced Early Changes in Renal Function among Ferrochromium-Producing Workers,"Changes in renal function among ferrochromium workers in a ferroalloy facility in China were investigated. The study was conducted on 84 men and 38 women workers exposed to hexavalent chromium (7440473) compounds such a sodium-chromate (7775113) and chromium-hydroxide (1308141) in the ferrochromium producing workplace of a ferroalloy facility. The mean duration of employment was 12.0 years for men and 11.5 years for women. Of the 122 ferrochromium producing workers, 31 had skin ulcers and ulcer scars, 56 had irritations and mucosal ulcers, and 13 had nasal septum perforations. No noteworthy abnormal changes were found in the chest X-rays, liver function tests and electrocardiogram. Urine chromium levels were found to be elevated in the exposed group, about 1.8 times those in the control group. In workers with urine chromium levels exceeding 45 micrograms/gram creatinine, urine levels of gamma-glutamyl-transferase, N-acetyl-beta-D-glucosaminidase (NAG), alkaline-phosphatase, glutamic-oxalacetic-transaminase (GOT), and lactate-dehydrogenase were significantly increased. For workers with more than 10 years of exposure, gamma-glutamyl-transferase, NAG, and GOT were elevated. However, in the chromium exposed workers, with the exception for the values of NAG, no significant differences were noted between two different employment time subgroups. The authors suggest that long term exposure to chromium produces chronic renal injury, mainly involving the proximal tubule. A urinary chromium concentration of greater than 15 micrograms/gram of creatinine can be proposed as a threshold dosage for nephrotoxicity, and gamma-glutamyl-transferase, NAG and alkaline-phosphatase are all early sensitive indicators of renal injury.","Chromium-Induced Early Changes in Renal Function among Ferrochromium-Producing Workers Abs: Changes in renal function among ferrochromium workers in a ferroalloy facility in China were investigated. The study was conducted on 84 men and 38 women workers exposed to hexavalent chromium (7440473) compounds such a sodium-chromate (7775113) and chromium-hydroxide (1308141) in the ferrochromium producing workplace of a ferroalloy facility. The mean duration of employment was 12.0 years for men and 11.5 years for women. Of the 122 ferrochromium producing workers, 31 had skin ulcers and ulcer scars, 56 had irritations and mucosal ulcers, and 13 had nasal septum perforations. No noteworthy abnormal changes were found in the chest X-rays, liver function tests and electrocardiogram. Urine chromium levels were found to be elevated in the exposed group, about 1.8 times those in the control group. In workers with urine chromium levels exceeding 45 micrograms/gram creatinine, urine levels of gamma-glutamyl-transferase, N-acetyl-beta-D-glucosaminidase (NAG), alkaline-phosphatase, glutamic-oxalacetic-transaminase (GOT), and lactate-dehydrogenase were significantly increased. For workers with more than 10 years of exposure, gamma-glutamyl-transferase, NAG, and GOT were elevated. However, in the chromium exposed workers, with the exception for the values of NAG, no significant differences were noted between two different employment time subgroups. The authors suggest that long term exposure to chromium produces chronic renal injury, mainly involving the proximal tubule. A urinary chromium concentration of greater than 15 micrograms/gram of creatinine can be proposed as a threshold dosage for nephrotoxicity, and gamma-glutamyl-transferase, NAG and alkaline-phosphatase are all early sensitive indicators of renal injury."
1238380,Mathur and  Gupta 1994,Dermal Toxicity of Nickel and Chromium in Guinea Pigs,"The dermal toxicity of nickel (7440020) and chromium (7440473) was studied in guinea-pigs. Albino-guinea-pigs were administered 100mg/kg nickel as nickel-sulfate (7786814) or chromium as potassium-chromate (7789006) alone, or in combination topically daily for 15 or 30 days. The animals were killed at the end of the exposure period and the livers and kidneys were removed. Blood samples were collected for hemoglobin, hematocrit, and glucose determination. The liver and kidneys were assayed for magnesium dependent adenosine-triphosphatase (MgATPase), acid-phosphatase (ACP), glucose-6-phosphatase (G6P), nickel, and chromium. All treatments significantly increased hepatic MgATPase activity at both time points. Renal MgATPase activity was significantly increased by all treatments after 30 days. ACP and G6P activity were significantly increased in the liver by all treatments after 30 days. All treatments significantly increased blood glucose concentrations at both time points; the increases were more pronounced at the 30 day sampling time. Combined nickel and chromium exposure increased hemoglobin concentrations at both time points. Nickel and chromium accumulated in the liver and kidney following all treatments at both times. The authors conclude that industrial workers and other persons may be at risk resulting from dermal exposure to nickel and chromium. Dermal toxicity may be enhanced if simultaneous exposure to both metals occurs.","Dermal Toxicity of Nickel and Chromium in Guinea Pigs Abs: The dermal toxicity of nickel (7440020) and chromium (7440473) was studied in guinea-pigs. Albino-guinea-pigs were administered 100mg/kg nickel as nickel-sulfate (7786814) or chromium as potassium-chromate (7789006) alone, or in combination topically daily for 15 or 30 days. The animals were killed at the end of the exposure period and the livers and kidneys were removed. Blood samples were collected for hemoglobin, hematocrit, and glucose determination. The liver and kidneys were assayed for magnesium dependent adenosine-triphosphatase (MgATPase), acid-phosphatase (ACP), glucose-6-phosphatase (G6P), nickel, and chromium. All treatments significantly increased hepatic MgATPase activity at both time points. Renal MgATPase activity was significantly increased by all treatments after 30 days. ACP and G6P activity were significantly increased in the liver by all treatments after 30 days. All treatments significantly increased blood glucose concentrations at both time points; the increases were more pronounced at the 30 day sampling time. Combined nickel and chromium exposure increased hemoglobin concentrations at both time points. Nickel and chromium accumulated in the liver and kidney following all treatments at both times. The authors conclude that industrial workers and other persons may be at risk resulting from dermal exposure to nickel and chromium. Dermal toxicity may be enhanced if simultaneous exposure to both metals occurs."
1238372,Holness 1994,Characteristic Features of Occupational Dermatitis: Epidemiologic Studies of Occupational Skin Disease Reported by Contact Dermatitis Clinics,"Characteristics of occupational dermatitis were reviewed. The contribution of irritant contact dermatitis compared with allergic contact dermatitis to the overall incidence of occupational skin disease was discussed. Studies have suggested that occupational skin disease appears to preferentially affect younger workers and men have been overrepresented in this disease as well. The majority of workers with the disease have had hand involvement as reported in studies in North America and Canada while involvement of the arms, face, and eyelids has been more commonly seen in allergic contact dermatitis compared with cases of irritant contact dermatitis. Cases of occupational irritant dermatitis were reported to have a shorter duration compared with cases of allergic occupational dermatitis. Epoxy resin, mercapto mix, paraphenylenediamine (106503), and potassium-dichromate (7778509) have been consistently reported to give positive patch tests in tested individuals, and sex differences in patch test reactivity have been reported as well. Future directions in occupational contact dermatitis were discussed.","Characteristic Features of Occupational Dermatitis: Epidemiologic Studies of Occupational Skin Disease Reported by Contact Dermatitis Clinics Abs: Characteristics of occupational dermatitis were reviewed. The contribution of irritant contact dermatitis compared with allergic contact dermatitis to the overall incidence of occupational skin disease was discussed. Studies have suggested that occupational skin disease appears to preferentially affect younger workers and men have been overrepresented in this disease as well. The majority of workers with the disease have had hand involvement as reported in studies in North America and Canada while involvement of the arms, face, and eyelids has been more commonly seen in allergic contact dermatitis compared with cases of irritant contact dermatitis. Cases of occupational irritant dermatitis were reported to have a shorter duration compared with cases of allergic occupational dermatitis. Epoxy resin, mercapto mix, paraphenylenediamine (106503), and potassium-dichromate (7778509) have been consistently reported to give positive patch tests in tested individuals, and sex differences in patch test reactivity have been reported as well. Future directions in occupational contact dermatitis were discussed."
1238368,Torresani et al. 1993,Contact Urticaria Syndrome due to Phenylmercuric Acetate,"A case of contact urticaria syndrome following exposure to phenylmercuric-acetate (62384) in an atopic patient was reported. The patient was a 54 year old woman with a 20 year history of eczema on both hands and a 2 year history of facial edema associated with rhinoconjunctivitis and asthma. The patient reported a positive family history of atopy. Eosinophilia and a high total immunoglobulin-E titer were seen on laboratory tests. Patch testing was positive for thiuram mix, potassium-dichromate, benzalkonium-chloride and sodium-lauryl-sulfate; however, no reactivity was seen to these antigens when applied as open tests. Erythema and urticaria were noted on open tests using phenylmercuric-acetate which also induced aggravation of the facial edema and bronchospasms. The authors discuss the validity of including open testing in the diagnostic protocol for urticaria.","Contact Urticaria Syndrome due to Phenylmercuric Acetate Abs: A case of contact urticaria syndrome following exposure to phenylmercuric-acetate (62384) in an atopic patient was reported. The patient was a 54 year old woman with a 20 year history of eczema on both hands and a 2 year history of facial edema associated with rhinoconjunctivitis and asthma. The patient reported a positive family history of atopy. Eosinophilia and a high total immunoglobulin-E titer were seen on laboratory tests. Patch testing was positive for thiuram mix, potassium-dichromate, benzalkonium-chloride and sodium-lauryl-sulfate; however, no reactivity was seen to these antigens when applied as open tests. Erythema and urticaria were noted on open tests using phenylmercuric-acetate which also induced aggravation of the facial edema and bronchospasms. The authors discuss the validity of including open testing in the diagnostic protocol for urticaria."
1238367,Van Hoogstraten et al. 1993,Oral Induction of Tolerance to Nickel Sensitization in Mice,"Induction of oral tolerance to nickel (7440020) was studied in mice. BALB/c-mice were injected intradermally with 0, 0.03, 0.1, 0.3, or 1.0 milligram (mg) nickel-sulfate (7786814) and were challenged 5 to 14 days later with an emulsion containing 10 micrograms per kilogram nickel-sulfate on the dorsum of the ear to determine the optimal dose for inducing nickel hypersensitivity. The degree of sensitivity was assessed by measuring ear swelling. A sensitizing dose of 0.3mg nickel-sulfate followed by challenge 11 days later was found to be optimal, producing the maximum response 48 hours after challenge. Mice were treated intragastrically with 1mg nickel-sulfate, administered 10, 30, or 90mg per liter (mg/l) nickel-sulfate in their drinking water for 3 weeks, or reared in metal cages with covers and water nipples known to release nickel. Administering mice nickel-sulfate intragastrically or rearing them in nickel releasing cages reduced the level of nickel sensitization by 80 and 82%, respectively. Administration of nickel-sulfate in drinking water caused a dose related decrease in nickel sensitivity. Mice were administered 90mg/l nickel-sulfate or potassium-dichromate (7778509) in their drinking water for 3 weeks. Mice were then tested for nickel and chromium (7440473) sensitivity using the ear swelling test. Drinking water exposure to nickel-sulfate or potassium-dichromate induced tolerance to the respective metals. CD8(-) and CD8(+) cells were obtained from lymph nodes draining the digestive tract and spleens of mice that had been given 90mg/l nickel-sulfate in their drinking water for 3 weeks. These were injected into naive recipient mice 1 week later. CD8(+) cells from nickel-sulfate exposed mice caused a 65% suppression of nickel hypersensitivity in the recipient mice. Transfer of CD8(-) cells had no effect on nickel hypersensitivity. The authors conclude that nickel tolerance to nickel skin hypersensitivity can be induced by oral administration of nickel salts in mice. This mouse model can be used to elucidate underlying mechanisms of nickel sensitization and specific immunosuppression.","Oral Induction of Tolerance to Nickel Sensitization in Mice Abs: Induction of oral tolerance to nickel (7440020) was studied in mice. BALB/c-mice were injected intradermally with 0, 0.03, 0.1, 0.3, or 1.0 milligram (mg) nickel-sulfate (7786814) and were challenged 5 to 14 days later with an emulsion containing 10 micrograms per kilogram nickel-sulfate on the dorsum of the ear to determine the optimal dose for inducing nickel hypersensitivity. The degree of sensitivity was assessed by measuring ear swelling. A sensitizing dose of 0.3mg nickel-sulfate followed by challenge 11 days later was found to be optimal, producing the maximum response 48 hours after challenge. Mice were treated intragastrically with 1mg nickel-sulfate, administered 10, 30, or 90mg per liter (mg/l) nickel-sulfate in their drinking water for 3 weeks, or reared in metal cages with covers and water nipples known to release nickel. Administering mice nickel-sulfate intragastrically or rearing them in nickel releasing cages reduced the level of nickel sensitization by 80 and 82%, respectively. Administration of nickel-sulfate in drinking water caused a dose related decrease in nickel sensitivity. Mice were administered 90mg/l nickel-sulfate or potassium-dichromate (7778509) in their drinking water for 3 weeks. Mice were then tested for nickel and chromium (7440473) sensitivity using the ear swelling test. Drinking water exposure to nickel-sulfate or potassium-dichromate induced tolerance to the respective metals. CD8(-) and CD8(+) cells were obtained from lymph nodes draining the digestive tract and spleens of mice that had been given 90mg/l nickel-sulfate in their drinking water for 3 weeks. These were injected into naive recipient mice 1 week later. CD8(+) cells from nickel-sulfate exposed mice caused a 65% suppression of nickel hypersensitivity in the recipient mice. Transfer of CD8(-) cells had no effect on nickel hypersensitivity. The authors conclude that nickel tolerance to nickel skin hypersensitivity can be induced by oral administration of nickel salts in mice. This mouse model can be used to elucidate underlying mechanisms of nickel sensitization and specific immunosuppression."
1238360,Acciai et al. 1993,Allergic Contact Dermatitis in Caterers,"Allergic contact dermatitis was studied in food service workers. The study group consisted of 72 caterers, 42 females, 17 to 66 years old. The subjects included 21 cooks, 12 pastry cooks, 11 barmen, seven kitchen attendants, five greengrocer assistants, four butchers, three canteen attendants, three bakers, three food shop assistants, two pizza restaurant assistants, and one pizza restaurant cook. The subjects were patch tested with a standard allergen series and food related allergens such as butylated-hydroxyanisole (25013165) (BHA), sodium-bisulfite (7631905), Peru-balsam (8007009), allyl-disulfide (2179579) and fresh garlic, and thiuram mix. Sixteen subjects were diagnosed with occupational irritant contact dermatitis, 14 with occupational allergic contact dermatitis, 16 with nonoccupational allergic contact dermatitis, two with occupational protein contact dermatitis, one with candidal paronychia, and 19 with other nonoccupational skin diseases. Four had nonoccupational respiratory diseases. Among the 14 cases of occupational contact dermatitis, six occurred in cooks, four in pastry cooks, two in kitchen attendants, and one each in a food shop assistant and baker. Three cooks were sensitized to nickel-sulfate (7786814) and one each was sensitized to sodium-bisulfite, allyl-disulfide and fresh garlic, and thiuram mix. The four pastry cooks were sensitized to Peru-balsam and one was sensitized to BHA. One kitchen attendant was sensitized to Peru-balsam and one to nickel-sulfate. The food shop assistant was sensitized to Peru-balsam and nickel-sulfate. The baker was sensitized to nickel-sulfate and potassium-dichromate (7778509). The authors conclude that cooks, pastry cooks and kitchen attendants are among the catering workers having the highest risk for allergic contact dermatitis.","Allergic Contact Dermatitis in Caterers Abs: Allergic contact dermatitis was studied in food service workers. The study group consisted of 72 caterers, 42 females, 17 to 66 years old. The subjects included 21 cooks, 12 pastry cooks, 11 barmen, seven kitchen attendants, five greengrocer assistants, four butchers, three canteen attendants, three bakers, three food shop assistants, two pizza restaurant assistants, and one pizza restaurant cook. The subjects were patch tested with a standard allergen series and food related allergens such as butylated-hydroxyanisole (25013165) (BHA), sodium-bisulfite (7631905), Peru-balsam (8007009), allyl-disulfide (2179579) and fresh garlic, and thiuram mix. Sixteen subjects were diagnosed with occupational irritant contact dermatitis, 14 with occupational allergic contact dermatitis, 16 with nonoccupational allergic contact dermatitis, two with occupational protein contact dermatitis, one with candidal paronychia, and 19 with other nonoccupational skin diseases. Four had nonoccupational respiratory diseases. Among the 14 cases of occupational contact dermatitis, six occurred in cooks, four in pastry cooks, two in kitchen attendants, and one each in a food shop assistant and baker. Three cooks were sensitized to nickel-sulfate (7786814) and one each was sensitized to sodium-bisulfite, allyl-disulfide and fresh garlic, and thiuram mix. The four pastry cooks were sensitized to Peru-balsam and one was sensitized to BHA. One kitchen attendant was sensitized to Peru-balsam and one to nickel-sulfate. The food shop assistant was sensitized to Peru-balsam and nickel-sulfate. The baker was sensitized to nickel-sulfate and potassium-dichromate (7778509). The authors conclude that cooks, pastry cooks and kitchen attendants are among the catering workers having the highest risk for allergic contact dermatitis."
1238357,Fielder et al. 1993,Report of the BTS Working Group on Dose Setting in In-Vivo Mutagenicity Assays,"Identification of a dose level for various chemicals that produced evident toxicity was reported. This toxic dose would be such that a significant increase would be expected to result in extremely severe toxic signs and probable mortality. The British Toxicology Societynited Kingdom Environmental Mutagenicity Society group concentrated on bone marrow assays, specifically the widely used micronucleus test. Specific compounds examined through literature search techniques included azathioprine (446866), benzene (71432), chromate and potassium-dichromate (7778509), cyclophosphamide (50180), acrylamide (79061), benzidine (92875), dimethylhydrazine (57147), and ethylene-oxide (79061). The group was searching for a value of 2 grams/kilogram for single oral dosing and 1 gram/kilogram for repeated dosing. Few data were found to be available, and these were limited essentially to the micronucleus test. In many cases the protocols were less rigorous than currently recommended. The data available indicated that about 90% of the tested mutagens would have been identified using a maximum tolerated dose based on nonlethal criteria. The percentage was expected to have been higher if all tests had been carried out under currently accepted protocol controls. Even so, the possibility of missing compounds was not completely ruled out.","Report of the BTS Working Group on Dose Setting in In-Vivo Mutagenicity Assays Abs: Identification of a dose level for various chemicals that produced evident toxicity was reported. This toxic dose would be such that a significant increase would be expected to result in extremely severe toxic signs and probable mortality. The British Toxicology Societynited Kingdom Environmental Mutagenicity Society group concentrated on bone marrow assays, specifically the widely used micronucleus test. Specific compounds examined through literature search techniques included azathioprine (446866), benzene (71432), chromate and potassium-dichromate (7778509), cyclophosphamide (50180), acrylamide (79061), benzidine (92875), dimethylhydrazine (57147), and ethylene-oxide (79061). The group was searching for a value of 2 grams/kilogram for single oral dosing and 1 gram/kilogram for repeated dosing. Few data were found to be available, and these were limited essentially to the micronucleus test. In many cases the protocols were less rigorous than currently recommended. The data available indicated that about 90% of the tested mutagens would have been identified using a maximum tolerated dose based on nonlethal criteria. The percentage was expected to have been higher if all tests had been carried out under currently accepted protocol controls. Even so, the possibility of missing compounds was not completely ruled out."
1238355,Goldschmidt et al. 1993,On the Substitution for Carcinogens in the Working Environment,"Strategies for removing carcinogenic substances from the workplace based on substitution were discussed. Regulations governing the use of carcinogens in Danish workplaces were summarized. Methods for substituting for carcinogens in workplaces were considered. Carcinogens can be removed by substituting a noncarcinogenic substance for the carcinogen or by introducing a new process where no carcinogens are used. A method for systematically finding a viable substitute chemical or process, known as functional analysis, was described. Functional analysis conceptualized substitution as a process and was based on identifying the problem, identifying and developing a range of substitutions (alternatives), identifying the consequences of implementing the alternatives, comparing the consequences, deciding on an appropriate alternative, implementing the alternative, and evaluating the results. A computer software program designed to assist in the functional analysis process was described. The program known as SUBTEC included physicochemical data on chemicals and processes used in different Danish industries, physicochemical data on nonhazardous chemicals that can be used to replace hazardous products, and procedures for searching for alternatives. Examples of substitutions used in Danish workplaces were discussed. These included replacing a paint containing lead-chromate (7758976) used for painting models in a ceramic factory with a paint not containing lead-chromate, and redesigning a process for assembling polyvinyl-chloride tubes that originally used a glue containing dimethylformamide (68122) so that only mechanical assembly was required.","On the Substitution for Carcinogens in the Working Environment Abs: Strategies for removing carcinogenic substances from the workplace based on substitution were discussed. Regulations governing the use of carcinogens in Danish workplaces were summarized. Methods for substituting for carcinogens in workplaces were considered. Carcinogens can be removed by substituting a noncarcinogenic substance for the carcinogen or by introducing a new process where no carcinogens are used. A method for systematically finding a viable substitute chemical or process, known as functional analysis, was described. Functional analysis conceptualized substitution as a process and was based on identifying the problem, identifying and developing a range of substitutions (alternatives), identifying the consequences of implementing the alternatives, comparing the consequences, deciding on an appropriate alternative, implementing the alternative, and evaluating the results. A computer software program designed to assist in the functional analysis process was described. The program known as SUBTEC included physicochemical data on chemicals and processes used in different Danish industries, physicochemical data on nonhazardous chemicals that can be used to replace hazardous products, and procedures for searching for alternatives. Examples of substitutions used in Danish workplaces were discussed. These included replacing a paint containing lead-chromate (7758976) used for painting models in a ceramic factory with a paint not containing lead-chromate, and redesigning a process for assembling polyvinyl-chloride tubes that originally used a glue containing dimethylformamide (68122) so that only mechanical assembly was required."
1238352,Isaksson et al. 1993,Contact Allergy to Duraphat,"Cases of contact allergy to colophony, a component of the fluoride varnish Duraphat were described. The first case involved a 49 year old dental nurse with a history of irritant dermatitis on the hands. She was patch tested with a standard series and a dental screening series as well as extracts of rubber gloves. Positive reactions to cobalt-chloride, colophony, nickel-sulfate, Kathon-CG, and potassium-bichromate were found. Duraphat was found to contain colophony. Patch testing with Duraphat alone or in petroleum provided strong positive reactions. The second case involved a 56 year old woman who received Duraphat fluoride varnish for caries prevention. Each of her two treatments resulted in edema of the tongue, soft palate, and upper lip. Preliminary patch testing did not yield clinically relevant findings for colophony; however, subsequent testing with Duraphat and colophony resulted in positive reactions to the highest concentrations. The first patient may have been sensitized to colophony in Duraphat and the second had a history of plaster sensitivity. The authors conclude that dental personnel are at risk of developing contact allergy to Duraphat, and patients should be asked about colophony sensitivity prior to Duraphat treatment.","Contact Allergy to Duraphat Abs: Cases of contact allergy to colophony, a component of the fluoride varnish Duraphat were described. The first case involved a 49 year old dental nurse with a history of irritant dermatitis on the hands. She was patch tested with a standard series and a dental screening series as well as extracts of rubber gloves. Positive reactions to cobalt-chloride, colophony, nickel-sulfate, Kathon-CG, and potassium-bichromate were found. Duraphat was found to contain colophony. Patch testing with Duraphat alone or in petroleum provided strong positive reactions. The second case involved a 56 year old woman who received Duraphat fluoride varnish for caries prevention. Each of her two treatments resulted in edema of the tongue, soft palate, and upper lip. Preliminary patch testing did not yield clinically relevant findings for colophony; however, subsequent testing with Duraphat and colophony resulted in positive reactions to the highest concentrations. The first patient may have been sensitized to colophony in Duraphat and the second had a history of plaster sensitivity. The authors conclude that dental personnel are at risk of developing contact allergy to Duraphat, and patients should be asked about colophony sensitivity prior to Duraphat treatment."
1238351,Freeman 1993,Occupational Skin Disease in New South Wales,"The occupational skin disease problem in New South Wales, Australia was reviewed. The results of a study of occupational skin disease conducted by the Contact and Occupational Skin Disease Clinic of the Skin and Cancer Foundation (SCF), New South Wales were discussed. Approximately 570 patients were diagnosed with occupational contact dermatitis between 1984 and 1989. This represented about 25% of the patients seen at the SCF during the period. Only 27.4% of the patients who were eligible for workers compensation benefits had taken the benefits. The major industries in which contact dermatitis occurred ranked in descending order were hairdressing, food, construction, medicine, printing, maintenance, laboratories, automobiles, farming including floral horticulture, and machining. Hairdressing, food, construction, and medicine together accounted for 43.5% of the patients. Construction workers lost an average of 3 months working time, compared to the average of 1 month lost for the total SCF population. Allergic contact dermatitis accounted for 67% of the cases in construction workers, compared to just 38.2% of the cases in the total population. Potassium-dichromate (7778509) was the most frequently identified allergen, both in the construction workers and total SCF population. The overall cost of occupational skin diseases in New South Wales has been estimated to be at least 12 million dollars. A total of 396 patients in the SCF population were followed up for 1 to 5 years. Of these, 70% improved. Only 5% showed a worsening of their dermatitis. The dermatitis in the remaining 25% remained roughly constant. Patients leaving their job showed the best prognosis. The prognosis in the construction industry was poorer than in the total SCF population. Patients with potassium-dichromate induced allergic contact dermatitis had the worst prognosis. The author concludes that interventions should be targeted at the populations most at risk. They should focus on education and prevention.","Occupational Skin Disease in New South Wales Abs: The occupational skin disease problem in New South Wales, Australia was reviewed. The results of a study of occupational skin disease conducted by the Contact and Occupational Skin Disease Clinic of the Skin and Cancer Foundation (SCF), New South Wales were discussed. Approximately 570 patients were diagnosed with occupational contact dermatitis between 1984 and 1989. This represented about 25% of the patients seen at the SCF during the period. Only 27.4% of the patients who were eligible for workers compensation benefits had taken the benefits. The major industries in which contact dermatitis occurred ranked in descending order were hairdressing, food, construction, medicine, printing, maintenance, laboratories, automobiles, farming including floral horticulture, and machining. Hairdressing, food, construction, and medicine together accounted for 43.5% of the patients. Construction workers lost an average of 3 months working time, compared to the average of 1 month lost for the total SCF population. Allergic contact dermatitis accounted for 67% of the cases in construction workers, compared to just 38.2% of the cases in the total population. Potassium-dichromate (7778509) was the most frequently identified allergen, both in the construction workers and total SCF population. The overall cost of occupational skin diseases in New South Wales has been estimated to be at least 12 million dollars. A total of 396 patients in the SCF population were followed up for 1 to 5 years. Of these, 70% improved. Only 5% showed a worsening of their dermatitis. The dermatitis in the remaining 25% remained roughly constant. Patients leaving their job showed the best prognosis. The prognosis in the construction industry was poorer than in the total SCF population. Patients with potassium-dichromate induced allergic contact dermatitis had the worst prognosis. The author concludes that interventions should be targeted at the populations most at risk. They should focus on education and prevention."
1238349,Kawahara et al. 1993,Further Epidemiologic Study of Occupational Contact Dermatitis in the Dental Clinic,"A study of the incidence of occupational contact dermatitis in dental technicians was conducted. The study group consisted of 12 male students at a Japanese dental technology school, average age 20 years. None had a history of allergic disorders. They were patch tested with a series of 40 dental contactants. The patches were read 2 and 3 days after application using the system of the Japanese Patch Test Research Group. Skin irritancy was scored on a 100 point scale. Gypsum casts of the reactive skin sites were prepared and examined using a micrometer and microscope. Potassium-dichromate (7778509), ammoniated-mercuric-chloride (10124488), sodium-thiosulfatoaurate (15283451), copper-sulfate (7758987), and 4,4'-diaminodiphenylmethane (101779) produced positive reactions in five subjects. Irritancy scores ranged from 0 to 37.5%. Gypsum casts of the reactive skin sites indicated that the reactive areas had significantly increased length and height compared to nonreactive areas. Dental laboratory procedures that could cause the observed patch test reactions, and procedures for controlling exposure were discussed.","Further Epidemiologic Study of Occupational Contact Dermatitis in the Dental Clinic Abs: A study of the incidence of occupational contact dermatitis in dental technicians was conducted. The study group consisted of 12 male students at a Japanese dental technology school, average age 20 years. None had a history of allergic disorders. They were patch tested with a series of 40 dental contactants. The patches were read 2 and 3 days after application using the system of the Japanese Patch Test Research Group. Skin irritancy was scored on a 100 point scale. Gypsum casts of the reactive skin sites were prepared and examined using a micrometer and microscope. Potassium-dichromate (7778509), ammoniated-mercuric-chloride (10124488), sodium-thiosulfatoaurate (15283451), copper-sulfate (7758987), and 4,4'-diaminodiphenylmethane (101779) produced positive reactions in five subjects. Irritancy scores ranged from 0 to 37.5%. Gypsum casts of the reactive skin sites indicated that the reactive areas had significantly increased length and height compared to nonreactive areas. Dental laboratory procedures that could cause the observed patch test reactions, and procedures for controlling exposure were discussed."
1238348,Guidotti et al. 1992,Hazards of Welding Technologies,"Health hazards associated with welding were discussed. Welding consists of a number of complex operations that include exposure to potentially toxic gases including nitrogen-dioxide (10102440) and ozone (10028156), metal fumes including chromium oxides, hexavalent-chromium (18540299), nickel (7440020) and iron (7439896) particles, infrared and ultraviolet radiation, and extremes of temperature. A major source of welding associated health problems is the metal being welded. The metal workpieces are frequently coated, painted, or galvanized or consist of alloys containing relatively hazardous constituents. The various types of welding techniques and their potential for producing fumes were described. Physical hazards associated with welding were discussed. These include eye injuries caused by flying metal particles and exposure to ultraviolet radiation from the welding arc, musculoskeletal problems caused by having to lift, move, or reposition heavy objects, and thermal burns caused by contact with hot metal fragments. Biological hazards associated with welding was considered. These include arc welders pneumoconiosis, nonspecific respiratory disorders, metal fume fever, cadmium (7440439) pneumonitis caused by welding cadmium containing alloys, fertility problems, and cancer. A number of studies have found excesses of lung, genitourinary, nasal, and laryngeal cancer and acute myeloid leukemia in various welding groups. Interpreting thesedata is complicated by confounding caused by multiple exposures. For example, a study of shipyard welders showed excesses of lung cancer, bladder cancer, and mesothelioma when compared to other nonwelding industrial workers. These findings suggested that the welders were probably exposed to several carcinogens including asbestos (1332214). Monitoring exposure to welding fumes during welding was discussed.","Hazards of Welding Technologies Abs: Health hazards associated with welding were discussed. Welding consists of a number of complex operations that include exposure to potentially toxic gases including nitrogen-dioxide (10102440) and ozone (10028156), metal fumes including chromium oxides, hexavalent-chromium (18540299), nickel (7440020) and iron (7439896) particles, infrared and ultraviolet radiation, and extremes of temperature. A major source of welding associated health problems is the metal being welded. The metal workpieces are frequently coated, painted, or galvanized or consist of alloys containing relatively hazardous constituents. The various types of welding techniques and their potential for producing fumes were described. Physical hazards associated with welding were discussed. These include eye injuries caused by flying metal particles and exposure to ultraviolet radiation from the welding arc, musculoskeletal problems caused by having to lift, move, or reposition heavy objects, and thermal burns caused by contact with hot metal fragments. Biological hazards associated with welding was considered. These include arc welders pneumoconiosis, nonspecific respiratory disorders, metal fume fever, cadmium (7440439) pneumonitis caused by welding cadmium containing alloys, fertility problems, and cancer. A number of studies have found excesses of lung, genitourinary, nasal, and laryngeal cancer and acute myeloid leukemia in various welding groups. Interpreting thesedata is complicated by confounding caused by multiple exposures. For example, a study of shipyard welders showed excesses of lung cancer, bladder cancer, and mesothelioma when compared to other nonwelding industrial workers. These findings suggested that the welders were probably exposed to several carcinogens including asbestos (1332214). Monitoring exposure to welding fumes during welding was discussed."
1238344,Triebig et al. 1992,"Neurotoxicity of Solvent Mixtures in Spray Painters. I. Study Design, Workplace Exposure, and Questionnaire","A study was conducted to assess exposure to solvent mixtures and subjective symptoms reported by painters engaged in spray painting activities. The study subjects included 163 male workers, 105 of whom were exposed as spray painters with at least 10 years of working experience, and 458 workers without any relevant occupational contact with solvents. The responses to questions did not produce a typical picture of neuropsychiatric symptoms in the exposed painters. The differential analysis of the incidence of symptoms showed that age was more important than length of solvent exposure. Only in the case of methyl-hippuric-acid in urine spot samples did the spray painters show a higher mean value than comparisons, indicating recent xylene (1330207) exposure. In 28 spray painters the urine studies showed elevated chromium (7440473) concentrations as a result of using zinc-chromate (14018952) containing wash primers without taking measures to protect themselves from contamination. Health complaints like increased tiredness, deterioration in short term memory, and headache were equally frequent in spray painters and comparisons.","Neurotoxicity of Solvent Mixtures in Spray Painters. I. Study Design, Workplace Exposure, and Questionnaire Abs: A study was conducted to assess exposure to solvent mixtures and subjective symptoms reported by painters engaged in spray painting activities. The study subjects included 163 male workers, 105 of whom were exposed as spray painters with at least 10 years of working experience, and 458 workers without any relevant occupational contact with solvents. The responses to questions did not produce a typical picture of neuropsychiatric symptoms in the exposed painters. The differential analysis of the incidence of symptoms showed that age was more important than length of solvent exposure. Only in the case of methyl-hippuric-acid in urine spot samples did the spray painters show a higher mean value than comparisons, indicating recent xylene (1330207) exposure. In 28 spray painters the urine studies showed elevated chromium (7440473) concentrations as a result of using zinc-chromate (14018952) containing wash primers without taking measures to protect themselves from contamination. Health complaints like increased tiredness, deterioration in short term memory, and headache were equally frequent in spray painters and comparisons."
1238340,Fisher 1992,Zinc,"The toxicological aspects of exposure to zinc (7440666) (Zn) and its compounds were reviewed. Exposure to Zn occurs mainly in smelting, galvanizing, and diecasting operations. Zinc-oxide (1314132) is used in the rubber industry, and in paints, cosmetics, fungicides, ceramic glazes, batteries, and dental cements. The most common route of exposure is dietary. The absorption, metabolism and excretion of Zn were discussed. Symptoms of acute Zn poisoning are primarily gastrointestinal, and toxicity is self limiting. Target organ toxicities were discussed, including skin (dermatitis), eye (corneal opacities, glaucoma), lung (cough, dyspnea, adult respiratory distress syndrome), digestive system (nausea, vomiting, diarrhea, hematemesis), kidney (microhematuria), nervous system (fatigue), and blood (anemia and leukopenia). Metal fume fever syndrome was also considered. No chronic or longterm effects other than corneal and lens opacities have been observed. No evidence was available for the teratogenicity or carcinogenicity of Zn in humans. The management of Zn toxicity was discussed, including clinical examination, treatment (supportive therapy), laboratory diagnosis, and biologic and environmental monitoring. The OSHA exposure limits for zinc-chloride (7646857), zinc-chromate (13530659), and dust and fumes of zinc-stearate (557051) and Zn metal were listed.","Zinc Abs: The toxicological aspects of exposure to zinc (7440666) (Zn) and its compounds were reviewed. Exposure to Zn occurs mainly in smelting, galvanizing, and diecasting operations. Zinc-oxide (1314132) is used in the rubber industry, and in paints, cosmetics, fungicides, ceramic glazes, batteries, and dental cements. The most common route of exposure is dietary. The absorption, metabolism and excretion of Zn were discussed. Symptoms of acute Zn poisoning are primarily gastrointestinal, and toxicity is self limiting. Target organ toxicities were discussed, including skin (dermatitis), eye (corneal opacities, glaucoma), lung (cough, dyspnea, adult respiratory distress syndrome), digestive system (nausea, vomiting, diarrhea, hematemesis), kidney (microhematuria), nervous system (fatigue), and blood (anemia and leukopenia). Metal fume fever syndrome was also considered. No chronic or longterm effects other than corneal and lens opacities have been observed. No evidence was available for the teratogenicity or carcinogenicity of Zn in humans. The management of Zn toxicity was discussed, including clinical examination, treatment (supportive therapy), laboratory diagnosis, and biologic and environmental monitoring. The OSHA exposure limits for zinc-chloride (7646857), zinc-chromate (13530659), and dust and fumes of zinc-stearate (557051) and Zn metal were listed."
1238336,Anonymous 1992,Micronucleus Test with Mouse Peripheral Blood Erythrocytes by Acridine Orange Supravital Staining: The Summary Report of the 5th Collaborative Study by CSGMT-MMS. The Collaborative Study Group for the Micronucleus Test,"The validation of a new micronucleus test using mouse peripheral blood erythrocytes supravitally stained with acridine-orange was reported by the Collaborative Study Group for the Micronucleus Test. Genotoxicity testing was performed using peripheral blood collected from male CD-1-mice treated once intraperitoneally or by gavage with the following 23 mutagens: cyclophosphamide-monohydrate (6055192), dimethylnitrosamine (62759), ethyl-methanesulfonate (62500), N-ethyl-N-nitrosourea (759739), methyl-methanesulfonate (66273), N-methyl-N'-nitro-N-nitrosoguanidine (70257), triethylenemelamine (51183), 1-beta-D-arabinofuranosylcytosine (147944), 5-fluorouracil (51218), 6-mercaptopurine (50442), methotrexate (59052), 2-acetylaminofluorene (53963), phenacetin (62442), benzo(a)pyrene (50328), 7,12-dimethylbenz(a)anthracene (57976), mitomycin-C (50077), potassium-bromate (7758012), potassium-chromate(VI) (7789006), colchicine (64868), vincristine-sulfate (2068782), benzene (71432), procarbazine-hydrochloride (366701), and urethane (51796). The peripheral blood was examined at 0, 24, 48, and 72 hours after treatment. Micronucleated peripheral reticulocyte frequencies were recorded based on the observation of 1000 reticulocytes per mouse. A dose dependent increase in the induction of micronucleated peripheral reticulocytes was observed for all chemicals tested. Most of the chemicals exhibited a maximum response 48 hours after treatment. Interlaboratory comparisons showed minor or no differences in results for most chemicals tested. The authors conclude that the acridine-orange supravital staining method using mouse peripheral blood erythrocytes is effective for the evaluation of chemical clastogenicity.","Micronucleus Test with Mouse Peripheral Blood Erythrocytes by Acridine Orange Supravital Staining: The Summary Report of the 5th Collaborative Study by CSGMT-MMS. The Collaborative Study Group for the Micronucleus Test Abs: The validation of a new micronucleus test using mouse peripheral blood erythrocytes supravitally stained with acridine-orange was reported by the Collaborative Study Group for the Micronucleus Test. Genotoxicity testing was performed using peripheral blood collected from male CD-1-mice treated once intraperitoneally or by gavage with the following 23 mutagens: cyclophosphamide-monohydrate (6055192), dimethylnitrosamine (62759), ethyl-methanesulfonate (62500), N-ethyl-N-nitrosourea (759739), methyl-methanesulfonate (66273), N-methyl-N'-nitro-N-nitrosoguanidine (70257), triethylenemelamine (51183), 1-beta-D-arabinofuranosylcytosine (147944), 5-fluorouracil (51218), 6-mercaptopurine (50442), methotrexate (59052), 2-acetylaminofluorene (53963), phenacetin (62442), benzo(a)pyrene (50328), 7,12-dimethylbenz(a)anthracene (57976), mitomycin-C (50077), potassium-bromate (7758012), potassium-chromate(VI) (7789006), colchicine (64868), vincristine-sulfate (2068782), benzene (71432), procarbazine-hydrochloride (366701), and urethane (51796). The peripheral blood was examined at 0, 24, 48, and 72 hours after treatment. Micronucleated peripheral reticulocyte frequencies were recorded based on the observation of 1000 reticulocytes per mouse. A dose dependent increase in the induction of micronucleated peripheral reticulocytes was observed for all chemicals tested. Most of the chemicals exhibited a maximum response 48 hours after treatment. Interlaboratory comparisons showed minor or no differences in results for most chemicals tested. The authors conclude that the acridine-orange supravital staining method using mouse peripheral blood erythrocytes is effective for the evaluation of chemical clastogenicity."
1238335,Braunlich et al. 1992,Nephrotoxicity of Chromate in Rats with Impaired Kidney Function,"Female Wistar-rats were dosed with sodium-dichromate (10588019) at levels of 1 or 2 milligrams/100 grams body weight subcutaneously in an effort to determine whether an impairment in kidney function could influence the degree of nephrotoxicity demonstrated by chromate. Experiments were performed on 120 day old female 5/6 nephrectomized Wistar-rats. Dosing occurred 1 week after the surgery and measurements were performed on days two, five, and nine after chromate dosing. Signs of nephrotoxicity were noted following the administration of a single dose of sodium-chromate and included increased proteinuria, oliguria and a diminution of renal excretion. The renal excretion of p-aminohippurate was dose dependent. A change was noted in the activities of lysosomal enzymes in kidney tissue. Blood urea nitrogen concentration was increased ten fold after dosing with the 2 milligrams/100 grams dose level. To characterize the influences of an impairment of kidney function on nephrotoxicity of sodium-dichromate the remnant kidney model was used.","Nephrotoxicity of Chromate in Rats with Impaired Kidney Function Abs: Female Wistar-rats were dosed with sodium-dichromate (10588019) at levels of 1 or 2 milligrams/100 grams body weight subcutaneously in an effort to determine whether an impairment in kidney function could influence the degree of nephrotoxicity demonstrated by chromate. Experiments were performed on 120 day old female 5/6 nephrectomized Wistar-rats. Dosing occurred 1 week after the surgery and measurements were performed on days two, five, and nine after chromate dosing. Signs of nephrotoxicity were noted following the administration of a single dose of sodium-chromate and included increased proteinuria, oliguria and a diminution of renal excretion. The renal excretion of p-aminohippurate was dose dependent. A change was noted in the activities of lysosomal enzymes in kidney tissue. Blood urea nitrogen concentration was increased ten fold after dosing with the 2 milligrams/100 grams dose level. To characterize the influences of an impairment of kidney function on nephrotoxicity of sodium-dichromate the remnant kidney model was used."
1238334,Checchi et al. 1992,Clinical Significance of Holes in Gloves for Dental Use: A Spectrophotometric Analysis,"A study was conducted to determine whether there is a relationship between latex glove faults that are detected by the leakage of liquid to the outside after filling, and the entry of liquid into the gloves during dental procedures. Twenty four gloves of different sizes were used in the study, and both large and small holes were randomly made on the index, middle and ring fingers of the golves. A filling method which consisted of filling the gloves with water followed by squeezing, was employed to detect the amount of water escaping, and a mass spectrophotometric assay was used to quantify the entry of an aqueous potassium-bichromate solution when a gloved hand was immersed in the solution. Disks of blotting paper were placed between the hand and the glove under each hole before immersion. The filling method was effective for revealing the faults of the gloves, but did not determine whether fluid entry would occur during work. Adherence of the glove to the hand seemed to be predictive for the amount of liquid entering the glove, while the size of the hole was not. The authors conclude that holes of the same size allowed contaminated liquid a greater entry in adherent gloves than in looser ones.","Clinical Significance of Holes in Gloves for Dental Use: A Spectrophotometric Analysis Abs: A study was conducted to determine whether there is a relationship between latex glove faults that are detected by the leakage of liquid to the outside after filling, and the entry of liquid into the gloves during dental procedures. Twenty four gloves of different sizes were used in the study, and both large and small holes were randomly made on the index, middle and ring fingers of the golves. A filling method which consisted of filling the gloves with water followed by squeezing, was employed to detect the amount of water escaping, and a mass spectrophotometric assay was used to quantify the entry of an aqueous potassium-bichromate solution when a gloved hand was immersed in the solution. Disks of blotting paper were placed between the hand and the glove under each hole before immersion. The filling method was effective for revealing the faults of the gloves, but did not determine whether fluid entry would occur during work. Adherence of the glove to the hand seemed to be predictive for the amount of liquid entering the glove, while the size of the hole was not. The authors conclude that holes of the same size allowed contaminated liquid a greater entry in adherent gloves than in looser ones."
1238333,Wang et al. 1992,17 Cases of Epoxy Resin Dermatitis in Shanghai,"Cases of contact dermatitis among electrical equipment factory workers were reported. Eczema was identified in 17 of 51 factory workers after exposure to nonbisphenol-A type epoxy resins and additives. Affected workers demonstrated an itchy erythematous papular vesicular dermatitis on the hands and face that spread to the forearms, neck, and chest. Upon patch testing, using the European standard series and epoxy resins and additives, three workers had a positive reaction to epoxy-resin-6360, one to the epoxy hardener, one to the HD electrician specialized filling powder, three to the epoxy resin contained in the standard series, two to para-tertiary-butylphenol-formaldehyde resin, one to nickel-sulfate (7786814), and one to potassium-dichromate (7778509). The authors conclude that epoxy-resin-6360, the epoxy hardener, and the HD electrician specialized filling powder may be allergens, and that other epoxy resins and additives may be irritants that result in mild chronic reactions upon exposure.","17 Cases of Epoxy Resin Dermatitis in Shanghai Abs: Cases of contact dermatitis among electrical equipment factory workers were reported. Eczema was identified in 17 of 51 factory workers after exposure to nonbisphenol-A type epoxy resins and additives. Affected workers demonstrated an itchy erythematous papular vesicular dermatitis on the hands and face that spread to the forearms, neck, and chest. Upon patch testing, using the European standard series and epoxy resins and additives, three workers had a positive reaction to epoxy-resin-6360, one to the epoxy hardener, one to the HD electrician specialized filling powder, three to the epoxy resin contained in the standard series, two to para-tertiary-butylphenol-formaldehyde resin, one to nickel-sulfate (7786814), and one to potassium-dichromate (7778509). The authors conclude that epoxy-resin-6360, the epoxy hardener, and the HD electrician specialized filling powder may be allergens, and that other epoxy resins and additives may be irritants that result in mild chronic reactions upon exposure."
1238330,Becker et al. 1992,Contact Allergens Modulate the Expression of MHC Class II Molecules on Murine Epidermal Langerhans Cells by Endocytotic Mechanisms,"The effects of contact allergens on MHC class-II molecules in mouse skin were examined. The ears of Balb/c-mice were treated topically with 0.3% 2,4-dinitrofluorobenzene (70348) (DNFB), 1% 1-chloro-2,4-dinitrobenzene (606213) (DNCB), 3% 4-ethoxymethylene-2-phenyl-oxazol-5-one (oxazolone), 1% 2,4,6-trinitrochlorobenzene (88880) (TNCB), 1% potassium-dichromate (7778509), or 1, 5, or 10% sodium-dodecyl-sulfate (1511213) (SDS). Three or 24 hours after application, selected mice were killed and epidermal cell suspensions were prepared from the ears. The effects on MHC class-II molecules were assessed by measuring Ia-antigen expression in Langerhans cells (LCs) using an immunofluorescence flow cytometric technique. DNFB caused a significant decrease in Ia-antigen expression 3 hours after application. By 24 hours post application Ia-antigen expression had increased to slightly above the control value. DNCB, oxazolone, potassium-dichromate, TNCB, and 5 and 10% SDS caused decreases in Ia-antigen expression. The strongest effects were induced by DNCB, potassium-dichromate, and 10% SDS. Freshly prepared or 3 day old cultures of mouse epidermal cells were incubated with 5 micrograms per milliliter (microg/ml) DNFB for 3 hours. In some experiments 1microg/ml brefeldin-A, 10 micromolar monensin, or 0.45 molar sucrose were present. The effects on Ia-antigen expression were determined as before. DNFB significantly decreased Ia-antigen expression in both freshly prepared and 3 day old cultures. Brefeldin-A and monensin did nor alter the effect of DNFB. Sucrose abolished the DNFB induced down regulation of Ia-antigen expression, indicating that endocytosis was involved in the down regulation. Epidermal cell suspensions preloaded with mouse MoAB-MK-D6 antibodies, an antibody that labeled surface Ia-antigen, were incubated with 5microg/ml DNFB. The effects on clearance of the labeled Ia molecules from the cell surface were determined. DNFB significantly accelerated clearance of the surface labeled Ia molecules. The authors conclude that DNFB and other contact allergens are able to decrease expression of MHC class-II molecules in LCs. Enhanced endocytosis of MHC class-II molecules is an early event in LC activation.","Contact Allergens Modulate the Expression of MHC Class II Molecules on Murine Epidermal Langerhans Cells by Endocytotic Mechanisms Abs: The effects of contact allergens on MHC class-II molecules in mouse skin were examined. The ears of Balb/c-mice were treated topically with 0.3% 2,4-dinitrofluorobenzene (70348) (DNFB), 1% 1-chloro-2,4-dinitrobenzene (606213) (DNCB), 3% 4-ethoxymethylene-2-phenyl-oxazol-5-one (oxazolone), 1% 2,4,6-trinitrochlorobenzene (88880) (TNCB), 1% potassium-dichromate (7778509), or 1, 5, or 10% sodium-dodecyl-sulfate (1511213) (SDS). Three or 24 hours after application, selected mice were killed and epidermal cell suspensions were prepared from the ears. The effects on MHC class-II molecules were assessed by measuring Ia-antigen expression in Langerhans cells (LCs) using an immunofluorescence flow cytometric technique. DNFB caused a significant decrease in Ia-antigen expression 3 hours after application. By 24 hours post application Ia-antigen expression had increased to slightly above the control value. DNCB, oxazolone, potassium-dichromate, TNCB, and 5 and 10% SDS caused decreases in Ia-antigen expression. The strongest effects were induced by DNCB, potassium-dichromate, and 10% SDS. Freshly prepared or 3 day old cultures of mouse epidermal cells were incubated with 5 micrograms per milliliter (microg/ml) DNFB for 3 hours. In some experiments 1microg/ml brefeldin-A, 10 micromolar monensin, or 0.45 molar sucrose were present. The effects on Ia-antigen expression were determined as before. DNFB significantly decreased Ia-antigen expression in both freshly prepared and 3 day old cultures. Brefeldin-A and monensin did nor alter the effect of DNFB. Sucrose abolished the DNFB induced down regulation of Ia-antigen expression, indicating that endocytosis was involved in the down regulation. Epidermal cell suspensions preloaded with mouse MoAB-MK-D6 antibodies, an antibody that labeled surface Ia-antigen, were incubated with 5microg/ml DNFB. The effects on clearance of the labeled Ia molecules from the cell surface were determined. DNFB significantly accelerated clearance of the surface labeled Ia molecules. The authors conclude that DNFB and other contact allergens are able to decrease expression of MHC class-II molecules in LCs. Enhanced endocytosis of MHC class-II molecules is an early event in LC activation."
1238328,Goh 1992,Comparative Study of TRUE Test and Finn Chamber Patch Test Techniques in Singapore,"The reactivity of the TRUE and Finn Chambers patch test techniques was compared in dermatology patients living in a tropical climate. The study group consisted of 413 patients, 217 males, mean age 34.5 years, treated for contact dermatitis at a Singapore dermatology clinic. They were patch tested simultaneously with panels one and two of the TRUE allergen series and the same allergens using the Finn Chamber technique. The allergens consisted of nickel-sulfate (7786814), p-phenylenediamine (106503) (PPD), neomycin (1404042), potassium-dichromate (7778509), caine mix, fragrance mix, colophony, epoxy resin, thiuram mix, balsam-of-Peru (8007009), ethylenediamine (107153), cobalt-chloride (7646799), a p-tert-butylphenol (98544) formaldehyde (50000) resin, parabens, carba mix, PPD mix, Kathon-CG (55965849), mercaptobenzothiazole (149304), lanolin (8006540), mercapto mix, thimerosal (54648), quinoline mix, and a negative control. Thirty eight percent of the patients had one or more positive reaction in the TRUE test and 42% had at least one positive reaction with the Finn Chambers procedure. The difference in reactivity was not statistically significant. The overall concordance of positive reactions was 63.7%. When only clinically relevant positive reactions were considered, the concordance rate increased marginally to 67%. The rate of discordant positive reactions obtained with the TRUE and Finn Chambers procedures was 11.6 and 21%, respectively. Positive reactions to PPD and neomycin were observed more frequently with the Finn Chambers than with the TRUE procedure. The author concludes that there appears to be good correlation between the TRUE and Finn chambers patch test techniques, but that the Finn Chambers procedure appears to be more sensitive to PPD and neomycin.","Comparative Study of TRUE Test and Finn Chamber Patch Test Techniques in Singapore Abs: The reactivity of the TRUE and Finn Chambers patch test techniques was compared in dermatology patients living in a tropical climate. The study group consisted of 413 patients, 217 males, mean age 34.5 years, treated for contact dermatitis at a Singapore dermatology clinic. They were patch tested simultaneously with panels one and two of the TRUE allergen series and the same allergens using the Finn Chamber technique. The allergens consisted of nickel-sulfate (7786814), p-phenylenediamine (106503) (PPD), neomycin (1404042), potassium-dichromate (7778509), caine mix, fragrance mix, colophony, epoxy resin, thiuram mix, balsam-of-Peru (8007009), ethylenediamine (107153), cobalt-chloride (7646799), a p-tert-butylphenol (98544) formaldehyde (50000) resin, parabens, carba mix, PPD mix, Kathon-CG (55965849), mercaptobenzothiazole (149304), lanolin (8006540), mercapto mix, thimerosal (54648), quinoline mix, and a negative control. Thirty eight percent of the patients had one or more positive reaction in the TRUE test and 42% had at least one positive reaction with the Finn Chambers procedure. The difference in reactivity was not statistically significant. The overall concordance of positive reactions was 63.7%. When only clinically relevant positive reactions were considered, the concordance rate increased marginally to 67%. The rate of discordant positive reactions obtained with the TRUE and Finn Chambers procedures was 11.6 and 21%, respectively. Positive reactions to PPD and neomycin were observed more frequently with the Finn Chambers than with the TRUE procedure. The author concludes that there appears to be good correlation between the TRUE and Finn chambers patch test techniques, but that the Finn Chambers procedure appears to be more sensitive to PPD and neomycin."
1238325,Fung and  Tang 1992,Aerosol Particle Analysis by Resonance Raman Spectroscopy,"The chemical characterization of crystalline and droplet aerosol particles was performed by resonance Raman spectroscopy enhanced by resonance excitation. Electrostatically charged solution droplets were transformed into solid particles in a particle containment chamber. The typical particle size studied ranged from 12 to 14 micrometers in diameter. A vibrating orifice generator was used to generate monodisperse droplets approximately 45 micrometers in diameter. The aerosol particle was excited by an argon ion laser with 500 milliwatts nominal laser power for a cycle duration of 5 milliseconds. Continuous illumination without gating was used for the monodisperse aerosol droplets. Sodium-nitrate was used as an internal standard to measure the preresonance Raman technique enhancement. The enhancement factor of 20 for sodium-chromate was attributed to the preresonance effect. The permanganate ion enhancement factor was measured to be approximately 300 in the resonance mode. The detection limit was 10(-3) molar, which was significantly lower than any ionic concentration detectable in a single solution droplet by the unenhanced Raman scattering method. The authors conclude that resonance enhancement makes resonance Raman spectroscopy a very useful quantitative analytical method for aerosol droplets.","Aerosol Particle Analysis by Resonance Raman Spectroscopy Abs: The chemical characterization of crystalline and droplet aerosol particles was performed by resonance Raman spectroscopy enhanced by resonance excitation. Electrostatically charged solution droplets were transformed into solid particles in a particle containment chamber. The typical particle size studied ranged from 12 to 14 micrometers in diameter. A vibrating orifice generator was used to generate monodisperse droplets approximately 45 micrometers in diameter. The aerosol particle was excited by an argon ion laser with 500 milliwatts nominal laser power for a cycle duration of 5 milliseconds. Continuous illumination without gating was used for the monodisperse aerosol droplets. Sodium-nitrate was used as an internal standard to measure the preresonance Raman technique enhancement. The enhancement factor of 20 for sodium-chromate was attributed to the preresonance effect. The permanganate ion enhancement factor was measured to be approximately 300 in the resonance mode. The detection limit was 10(-3) molar, which was significantly lower than any ionic concentration detectable in a single solution droplet by the unenhanced Raman scattering method. The authors conclude that resonance enhancement makes resonance Raman spectroscopy a very useful quantitative analytical method for aerosol droplets."
1238323,Rungby and  Ernst 1992,"Experimentally Induced Lipid Peroxidation after Exposure to Chromium, Mercury or Silver: Interactions with Carbon Tetrachloride","Chromium (7440473) (Cr) induced lipid peroxidation in the liver and kidney was studied. Increased toxicity of carbon-tetrachloride (56235) (CCl4) after preexposure to hexavalent Cr, organic and inorganic mercury (7439976) (Hg), or silver (7440224) (Ag) were examined. Kidneys and livers were obtained from male, 5 week old NMRI-mice that had been injected intraperitoneally with 8mg/kg sodium-chromate (7775113). The animals were sacrificed at 15 and 30 minutes and 1, 3, 24, and 48 hours. Mercuric-chloride (7487947) and methyl-mercury (22967926) were injected in some of the Cr treated groups. After 24 hours, half the animals were injected with CCl4 in paraffin-oil (1:4). The mice were decapitated 2 hours after the last injection. Cr exposure significantly increased malondialdehyde (MDA) levels in both liver and kidney. Liver levels peaked after 60 minutes and remained significantly higher than the controls at 48 hours. Kidney level normalized after 3 hours. Cr plus Hg or Ag exposure also resulted in significantly increased MDA levels in the organs. CCl4 treatment caused an increase of MDA levels in the liver, but not in the kidney. Preexposure to a single dose of the metals did not significantly increase lipid peroxidation after CCl4 exposure. The authors conclude that Cr, Hg, and Ag induce lipid peroxidation, but do not significantly increase CCl4 toxicity.","Experimentally Induced Lipid Peroxidation after Exposure to Chromium, Mercury or Silver: Interactions with Carbon Tetrachloride Abs: Chromium (7440473) (Cr) induced lipid peroxidation in the liver and kidney was studied. Increased toxicity of carbon-tetrachloride (56235) (CCl4) after preexposure to hexavalent Cr, organic and inorganic mercury (7439976) (Hg), or silver (7440224) (Ag) were examined. Kidneys and livers were obtained from male, 5 week old NMRI-mice that had been injected intraperitoneally with 8mg/kg sodium-chromate (7775113). The animals were sacrificed at 15 and 30 minutes and 1, 3, 24, and 48 hours. Mercuric-chloride (7487947) and methyl-mercury (22967926) were injected in some of the Cr treated groups. After 24 hours, half the animals were injected with CCl4 in paraffin-oil (1:4). The mice were decapitated 2 hours after the last injection. Cr exposure significantly increased malondialdehyde (MDA) levels in both liver and kidney. Liver levels peaked after 60 minutes and remained significantly higher than the controls at 48 hours. Kidney level normalized after 3 hours. Cr plus Hg or Ag exposure also resulted in significantly increased MDA levels in the organs. CCl4 treatment caused an increase of MDA levels in the liver, but not in the kidney. Preexposure to a single dose of the metals did not significantly increase lipid peroxidation after CCl4 exposure. The authors conclude that Cr, Hg, and Ag induce lipid peroxidation, but do not significantly increase CCl4 toxicity."
1238322,Gammelgaard et al. 1992,Simultaneous Determination of Chromium(III) and Chromium(VI) in Aqueous Solutions by Ion Chromatography and Chemiluminescence Detection,"A chemiluminescence method in combination with a flow system was developed to determine trivalent and hexavalent chromium (7440473) species in aqueous solutions. Standard solutions of chromium(III) and chromium(VI) were prepared from stock solutions of chromium-chloride (10025737) and potassium-chromate (7789006), respectively. The reducing agent used in this procedure was prepared from potassium-sulfate. Luminol and hydrogen-peroxide were used as the chemiluminescence reagents. Fifty microliters of test solution was separated by ion chromatography on a DIONEX Ionpac-CG5 guard column. The luminol/hydrogen-peroxide reagent was added just prior to chemiluminescence detection. Human skin penetration profiles of chromium compounds were performed in diffusion cells. The limit of detection for both chromium species was 0.5 micrograms per liter (microg/l), and the limit of determination was 1.6microg/l. The precision at the 20microg/l level was 3.5% for chromium(III) and 3.3% for chromium(VI). Calibration graphs showed linearity for both compounds between concentrations of 1 and 1000microg/l. The authors conclude that chemiluminescence with ion chromatography is an accurate method for the determination of chromium species in solution. Results are comparable with those obtained by atomic absorption spectrometry.","Simultaneous Determination of Chromium(III) and Chromium(VI) in Aqueous Solutions by Ion Chromatography and Chemiluminescence Detection Abs: A chemiluminescence method in combination with a flow system was developed to determine trivalent and hexavalent chromium (7440473) species in aqueous solutions. Standard solutions of chromium(III) and chromium(VI) were prepared from stock solutions of chromium-chloride (10025737) and potassium-chromate (7789006), respectively. The reducing agent used in this procedure was prepared from potassium-sulfate. Luminol and hydrogen-peroxide were used as the chemiluminescence reagents. Fifty microliters of test solution was separated by ion chromatography on a DIONEX Ionpac-CG5 guard column. The luminol/hydrogen-peroxide reagent was added just prior to chemiluminescence detection. Human skin penetration profiles of chromium compounds were performed in diffusion cells. The limit of detection for both chromium species was 0.5 micrograms per liter (microg/l), and the limit of determination was 1.6microg/l. The precision at the 20microg/l level was 3.5% for chromium(III) and 3.3% for chromium(VI). Calibration graphs showed linearity for both compounds between concentrations of 1 and 1000microg/l. The authors conclude that chemiluminescence with ion chromatography is an accurate method for the determination of chromium species in solution. Results are comparable with those obtained by atomic absorption spectrometry."
1238321,Cooper and  Gressel 1992,Real-Time Data Evaluation at a Bag-Emptying Operation: A Case Study,Real time techniques were used to identify and quantify dust exposures at repetitive tasks. The task studied was a bag emptying operation. The bags weighed 50 pounds and were loaded with lead-chromate (7758976). Videotapes were made of workers emptying 65 bags in a 24 minute period. Seven specific tasks were identified along with the relative contribution of each to the worker's overall dust exposure. Pushing empty bags into barrels for subsequent disposal was the major source of airborne dust. Lesser but significant amounts of dust became airborne when the bags were cut open and lifted to the emptying shelf of the dump station. The bag disposal unit within the dump station control system was awkward for the workers to use and necessitated disposal outside the control area. Redesign of the disposal system was associated with a 33% reduction in atmospheric dust. The authors encourage the use of video recording and dust monitoring overlay to improve work practices.,Real-Time Data Evaluation at a Bag-Emptying Operation: A Case Study Abs: Real time techniques were used to identify and quantify dust exposures at repetitive tasks. The task studied was a bag emptying operation. The bags weighed 50 pounds and were loaded with lead-chromate (7758976). Videotapes were made of workers emptying 65 bags in a 24 minute period. Seven specific tasks were identified along with the relative contribution of each to the worker's overall dust exposure. Pushing empty bags into barrels for subsequent disposal was the major source of airborne dust. Lesser but significant amounts of dust became airborne when the bags were cut open and lifted to the emptying shelf of the dump station. The bag disposal unit within the dump station control system was awkward for the workers to use and necessitated disposal outside the control area. Redesign of the disposal system was associated with a 33% reduction in atmospheric dust. The authors encourage the use of video recording and dust monitoring overlay to improve work practices.
1238316,Fischer and  Adams 1990,"Paints, Varnishes, and Lacquers","Skin disorders associated with exposure to paints, varnishes and lacquers were discussed. Paint which is on the market today may contain several synthetic resins, a carefully selected and balanced group of pigments, various solvents, driers, catalysts, extenders, plasticizers, mildew proofing agents, fire retardants, and in some cases sound proofing agents. Inorganic and organic pigments commonly used in the manufacture of paint were discussed. Vehicles for spreading the pigments included vegetable oils, natural resins, and synthetic resins. Other components of paints included solvents, hardeners, extenders, driers, emulsifiers, antifoaming agents, thixotropic agents, plasticizers, stabilizers, fungicides, antifouling agents, antioxidants, pH adjusters and photoinitiators. Manufacturing of paints, varnishes and lacquers was discussed. In spite of the many potential hazards present in these industries, the incidence of dermatitis was quite low, and those cases which occurred often were the result of contact with soaps, detergents, and solvents. Dermatologists should be aware of systemic symptoms which may result from inhalation of fumes of paint strippers and oil based paints. Painters working for long periods in poorly ventilated areas may experience dizziness, euphoria, headache, blurred vision and slurred speech. Patients with exposure to zinc-chromate have a significantly higher than expected incidence of lung cancer. Spray painters appear at greatest risk. Paint and grease guns can cause severe penetrating wounds of the hand.","Paints, Varnishes, and Lacquers Abs: Skin disorders associated with exposure to paints, varnishes and lacquers were discussed. Paint which is on the market today may contain several synthetic resins, a carefully selected and balanced group of pigments, various solvents, driers, catalysts, extenders, plasticizers, mildew proofing agents, fire retardants, and in some cases sound proofing agents. Inorganic and organic pigments commonly used in the manufacture of paint were discussed. Vehicles for spreading the pigments included vegetable oils, natural resins, and synthetic resins. Other components of paints included solvents, hardeners, extenders, driers, emulsifiers, antifoaming agents, thixotropic agents, plasticizers, stabilizers, fungicides, antifouling agents, antioxidants, pH adjusters and photoinitiators. Manufacturing of paints, varnishes and lacquers was discussed. In spite of the many potential hazards present in these industries, the incidence of dermatitis was quite low, and those cases which occurred often were the result of contact with soaps, detergents, and solvents. Dermatologists should be aware of systemic symptoms which may result from inhalation of fumes of paint strippers and oil based paints. Painters working for long periods in poorly ventilated areas may experience dizziness, euphoria, headache, blurred vision and slurred speech. Patients with exposure to zinc-chromate have a significantly higher than expected incidence of lung cancer. Spray painters appear at greatest risk. Paint and grease guns can cause severe penetrating wounds of the hand."
1238311,Cavaco et al. 1991,Dosimetry Commissioning for an Industrial Cobalt-60 Gamma-Radiation Facility,"The distribution of absorbed gamma radiation by products treated with radioactive cobalt was examined. Cardboard boxes were filled with folded and crumpled papers and dosimeters to a bulk density of 200 kilograms/cubic meter. The boxes were loaded into standard carriers used at a medical equipment sterilization facility. Dosimeter systems consisting of red and amber Perspex and radiochromic dye films as well as ethanol-monochlorobenzene and potassium-dichromate solutions were used to determine amounts of absorbed radiation dose after exposure to gamma radiation. Radiation dose distribution in air at a distance of 45 centimeters from the source rack in a vertical plane was shifted slightly toward the bottom of the symmetry level of the box carrier. Maximum dose distribution in the test boxes was on the surface facing the cobalt source and minimum doses were seen in the center of the boxes. Parameters such as dwell times for different minimum doses, source utilization efficiency, and uniformity ratio were calculated based on the size, volume, weight, and density of the paper loaded boxes.","Dosimetry Commissioning for an Industrial Cobalt-60 Gamma-Radiation Facility Abs: The distribution of absorbed gamma radiation by products treated with radioactive cobalt was examined. Cardboard boxes were filled with folded and crumpled papers and dosimeters to a bulk density of 200 kilograms/cubic meter. The boxes were loaded into standard carriers used at a medical equipment sterilization facility. Dosimeter systems consisting of red and amber Perspex and radiochromic dye films as well as ethanol-monochlorobenzene and potassium-dichromate solutions were used to determine amounts of absorbed radiation dose after exposure to gamma radiation. Radiation dose distribution in air at a distance of 45 centimeters from the source rack in a vertical plane was shifted slightly toward the bottom of the symmetry level of the box carrier. Maximum dose distribution in the test boxes was on the surface facing the cobalt source and minimum doses were seen in the center of the boxes. Parameters such as dwell times for different minimum doses, source utilization efficiency, and uniformity ratio were calculated based on the size, volume, weight, and density of the paper loaded boxes."
1238301,Huang et al. 1991,Allergologic Evaluation for Workers Exposed to Toluene Diisocyanate,"The incidence of sensitivity to toluene-diisocyanate (584849) (TDI) was examined in a group of 15 painters with occupational exposure to the chemical. The workers applied polyurethane varnish to furniture, 8 hours a day, 6 days a week. TDI air levels in the work area were monitored, and workers were questioned about allergic symptoms and tested for lung function, mast cell degranulation as a result of TDI exposure, and contact sensitivity to TDI, potassium-dichromate, Daconil and 5% formaldehyde. TDI concentrations in the air ranged from 0.07 to 0.17 parts per million. All workers reported eye, nose and throat irritation; 46.7% were symptomatic for chronic bronchitis; 26.7% reported dyspnea and wheezing while at work; and 20% had contact dermatitis. Referent subjects, who were not exposed to TDI, reported no contact dermatitis, bronchitis, wheezing or dyspnea. Lung function test results were decreased in the TDI exposed group compared with the referents. Mast cell degranulation percentage in response to challenge with TDI protein conjugates, was significantly increased in the workers. Five of 15 workers had positive reactions to patch testing with TDI, while no referents were positive. All subjects were negative for contact sensitivity to potassium-dichromate, Daconil and formaldehyde. The authors conclude that the results suggest that the polyurethane varnish painters suffered from allergic pulmonary disease and contact sensitivity induced by chronic exposure to TDI.","Allergologic Evaluation for Workers Exposed to Toluene Diisocyanate Abs: The incidence of sensitivity to toluene-diisocyanate (584849) (TDI) was examined in a group of 15 painters with occupational exposure to the chemical. The workers applied polyurethane varnish to furniture, 8 hours a day, 6 days a week. TDI air levels in the work area were monitored, and workers were questioned about allergic symptoms and tested for lung function, mast cell degranulation as a result of TDI exposure, and contact sensitivity to TDI, potassium-dichromate, Daconil and 5% formaldehyde. TDI concentrations in the air ranged from 0.07 to 0.17 parts per million. All workers reported eye, nose and throat irritation; 46.7% were symptomatic for chronic bronchitis; 26.7% reported dyspnea and wheezing while at work; and 20% had contact dermatitis. Referent subjects, who were not exposed to TDI, reported no contact dermatitis, bronchitis, wheezing or dyspnea. Lung function test results were decreased in the TDI exposed group compared with the referents. Mast cell degranulation percentage in response to challenge with TDI protein conjugates, was significantly increased in the workers. Five of 15 workers had positive reactions to patch testing with TDI, while no referents were positive. All subjects were negative for contact sensitivity to potassium-dichromate, Daconil and formaldehyde. The authors conclude that the results suggest that the polyurethane varnish painters suffered from allergic pulmonary disease and contact sensitivity induced by chronic exposure to TDI."
1238296,Borges et al. 1991,"Activation of chromium(VI) by thiols results in chromium(V) formation, chromium binding to DNA and altered DNA conformation","The ability of glutathione, cysteine, beta-mercaptoethanol (60242) (BME), and dithiothreitol (DTT) to activate hexavalent chromium (7440473) (Cr) to DNA damaging species was studied in-vitro. Potassium-dichromate (7778509) was incubated with supercoiled or linearized pBR322 plasmid DNA in the presence or absence of glutathione, cysteine, BME, or dithiothreitol and the extent of DNA binding was determined. The Cr+6 modified DNA was examined by agarose gel electrophoresis to detect any conformational changes. DNA modified by Cr+6 and DTT was also examined by transmission electron microscopy. Potassium-dichromate was reacted with glutathione, cysteine, BME, and DTT. The reaction mixtures were monitored by electron paramagnetic resonance spectroscopy to follow the formation and decay of Cr+5 and Cr+3 chromium species. The level of Cr binding was significantly increased when the thiols were present in the incubation mixture compared to Cr+6 alone. The greatest increase occurred with DTT, followed by BME, cysteine, and glutathione in that order. The extent of binding did not differ significantly between supercoiled and linearized DNA except when BME was used. Chromium/DNA binding was greater for the linearized form at low BME/Cr+6 ratios and greater for the supercoiled form when high BME/Cr+6 ratios were used. DTT and BME mediated Cr+6/DNA binding distorted the plasmid structure and inhibited migration of the plasmid. The extent of plasmid distortion was positively correlated with the degree of chromium/DNA binding. DTT mediated chromium/DNA complexes contained aggregates of several plasmids and kinked forms formed by plasmid condensation. No DNA strand breaks were seen. Cr+6 modified DNA mediated by glutathione and cysteine showed no conformational changes. Cr+6 was reduced to Cr+5 by the thiols. BME was the most effective, followed by DTT, glutathione, and cysteine in that order. Cr+3 was detected only after reaction with cysteine. The rates of reduction of Cr+6 with thiols decreased in the order cysteine, DTT, glutathione, and BME. The authors conclude that thiol mediated reduction of Cr+6 leads to the formation of chromium/DNA adducts. The rate of reaction and extent of DNA binding depend on the thiol used. The extent of binding also depends on the amount and stability of the Cr+5 species formed.","Activation of chromium(VI) by thiols results in chromium(V) formation, chromium binding to DNA and altered DNA conformation Abs: The ability of glutathione, cysteine, beta-mercaptoethanol (60242) (BME), and dithiothreitol (DTT) to activate hexavalent chromium (7440473) (Cr) to DNA damaging species was studied in-vitro. Potassium-dichromate (7778509) was incubated with supercoiled or linearized pBR322 plasmid DNA in the presence or absence of glutathione, cysteine, BME, or dithiothreitol and the extent of DNA binding was determined. The Cr+6 modified DNA was examined by agarose gel electrophoresis to detect any conformational changes. DNA modified by Cr+6 and DTT was also examined by transmission electron microscopy. Potassium-dichromate was reacted with glutathione, cysteine, BME, and DTT. The reaction mixtures were monitored by electron paramagnetic resonance spectroscopy to follow the formation and decay of Cr+5 and Cr+3 chromium species. The level of Cr binding was significantly increased when the thiols were present in the incubation mixture compared to Cr+6 alone. The greatest increase occurred with DTT, followed by BME, cysteine, and glutathione in that order. The extent of binding did not differ significantly between supercoiled and linearized DNA except when BME was used. Chromium/DNA binding was greater for the linearized form at low BME/Cr+6 ratios and greater for the supercoiled form when high BME/Cr+6 ratios were used. DTT and BME mediated Cr+6/DNA binding distorted the plasmid structure and inhibited migration of the plasmid. The extent of plasmid distortion was positively correlated with the degree of chromium/DNA binding. DTT mediated chromium/DNA complexes contained aggregates of several plasmids and kinked forms formed by plasmid condensation. No DNA strand breaks were seen. Cr+6 modified DNA mediated by glutathione and cysteine showed no conformational changes. Cr+6 was reduced to Cr+5 by the thiols. BME was the most effective, followed by DTT, glutathione, and cysteine in that order. Cr+3 was detected only after reaction with cysteine. The rates of reduction of Cr+6 with thiols decreased in the order cysteine, DTT, glutathione, and BME. The authors conclude that thiol mediated reduction of Cr+6 leads to the formation of chromium/DNA adducts. The rate of reaction and extent of DNA binding depend on the thiol used. The extent of binding also depends on the amount and stability of the Cr+5 species formed."
1238287,Mathur et al. 1991,Sensitivity to Chromium-Containing Automobile Parts,A case study was presented of allergic contact dermatitis due to chromium (7440473) in an automobile industry worker. The subject was a 33 year old man with an 8 to 10 month history of itching and redness of the fingers of both hands. He was employed in the automobile industry and had been handling chrome containing auto parts for the past year. On examination there were papular lesions with occasional eczematous vesicles and induration on the fingers of both hands; with the palmar surface more heavily involved than the dorsal surface. Patch testing achieved a positive reaction to potassium-dichromate (7778509). During his employment there had been periods of time when he was not handling chrome plated or chrome passivated automobile parts. It was noted that during these times his symptoms lessened. The disease also demonstrated remission on treatment with antihistamines and steroids. The subject was given topical treatment and advised to change jobs.,Sensitivity to Chromium-Containing Automobile Parts Abs: A case study was presented of allergic contact dermatitis due to chromium (7440473) in an automobile industry worker. The subject was a 33 year old man with an 8 to 10 month history of itching and redness of the fingers of both hands. He was employed in the automobile industry and had been handling chrome containing auto parts for the past year. On examination there were papular lesions with occasional eczematous vesicles and induration on the fingers of both hands; with the palmar surface more heavily involved than the dorsal surface. Patch testing achieved a positive reaction to potassium-dichromate (7778509). During his employment there had been periods of time when he was not handling chrome plated or chrome passivated automobile parts. It was noted that during these times his symptoms lessened. The disease also demonstrated remission on treatment with antihistamines and steroids. The subject was given topical treatment and advised to change jobs.
1238276,Kiec-Swierczynska 1990,Occupational Dermatoses and Allergy to Metals in Polish Construction Workers Manufacturing Prefabricated Building Units,"The incidence of occupational dermatoses and allergies in workers exposed to concrete, flyash, and asbestos (1332214) containing cement was studied. The cohort consisted of 1782 Polish workers, 1552 males, of whom 141 were employed at five power stations removing flyash, 149 were employed at a cement factory, 905 were employed in producing ordinary or cellular concrete from wet cement, 252 were employed in producing cellular concrete from wet ash, 157 were employed producing cellular concrete from wet ash and cement mixes, and 178 were involved in producing prefabricated units from asbestos cement and mineral wool. The comparisons consisted of 74 male lumberjacks and 37 female seamstresses. All subjects were given physical examinations and patch tested with a series of allergens that included potassium-dichromate (7778509), nickel-sulfate (7786814), and cobalt-chloride (7646799). The cement, ash, asbestos cement, and mineral wool were analyzed for chromium (7440473), cobalt (7440484), and nickel (7440020). Skin changes were found in 956 cohort subjects and 43 comparisons. Dermatitis and oil acne were the major skin disorders seen. Chromium allergy was found in 23% of the cohort. The prevalence of cobalt and nickel allergy in the cohort was 13.4 and 2.7%, respectively. The prevalences of chromium, cobalt, and nickel allergy in the cohort were significantly higher than in the comparisons and were highest in subjects exposed to cement, flyash, and asbestos cement. The nickel, chromium, and cobalt concentrations in flyash were two to three times higher than in cement. The author suggests that flyash has an irritant and allergic potential that is similar to that of asbestos cement.","Occupational Dermatoses and Allergy to Metals in Polish Construction Workers Manufacturing Prefabricated Building Units Abs: The incidence of occupational dermatoses and allergies in workers exposed to concrete, flyash, and asbestos (1332214) containing cement was studied. The cohort consisted of 1782 Polish workers, 1552 males, of whom 141 were employed at five power stations removing flyash, 149 were employed at a cement factory, 905 were employed in producing ordinary or cellular concrete from wet cement, 252 were employed in producing cellular concrete from wet ash, 157 were employed producing cellular concrete from wet ash and cement mixes, and 178 were involved in producing prefabricated units from asbestos cement and mineral wool. The comparisons consisted of 74 male lumberjacks and 37 female seamstresses. All subjects were given physical examinations and patch tested with a series of allergens that included potassium-dichromate (7778509), nickel-sulfate (7786814), and cobalt-chloride (7646799). The cement, ash, asbestos cement, and mineral wool were analyzed for chromium (7440473), cobalt (7440484), and nickel (7440020). Skin changes were found in 956 cohort subjects and 43 comparisons. Dermatitis and oil acne were the major skin disorders seen. Chromium allergy was found in 23% of the cohort. The prevalence of cobalt and nickel allergy in the cohort was 13.4 and 2.7%, respectively. The prevalences of chromium, cobalt, and nickel allergy in the cohort were significantly higher than in the comparisons and were highest in subjects exposed to cement, flyash, and asbestos cement. The nickel, chromium, and cobalt concentrations in flyash were two to three times higher than in cement. The author suggests that flyash has an irritant and allergic potential that is similar to that of asbestos cement."
1238274,Van der Wal 1990,Exposure of Welders to Fumes and Gases in Dutch Industries: Summary of Results,"An extensive study of the exposure of welders to chemical and physical agents at the workplace and in the laboratory was described and the following types of welding were examined: manual metal arc, metal active gas, metal inert gas, tungsten inert gas, submerged arc, and flux cored arc. The air in the breathing zone of the welders behind the face shield was sampled during two 8 hour shifts by personal sampling. Two types of face shield were used, the hand held welding shield and the welding helmet. Samples were also collected at stationary test sites at a distance of about 2 meters from the welder. The total welding fume concentrations at the stationary test sites, although sampled in close vicinity to the welders, were appreciably less than those in the breathing zone. Welders working in a ship built of steel primed with a red iron/epoxy resin primer were exposed in the breathing zone to up to 12 parts per million (ppm) of carbon-monoxide (630080) (CO), up to 0.04ppm of formaldehyde (50000) and 5 to 50mg/m3 of total welding fumes. The corresponding results for welding of steel contaminated with oil, also in a ship, were 4 to 19ppm CO, 2 to 3 micrograms/m3 of polycyclic aromatic hydrocarbons, 35 to 150 nanograms/cubic meter of benzo(a)pyrene (50328), and 3 to 55mg/m3 of total welding fumes. In a large ventilated room, the gas flame cutting of steel treated with a primer containing lead and zinc chromates produced the following concentrations of pollutants in the breathing zone of the cutters: up to 17 micrograms per cubic meter (microg/m3) of chromium (7440473), 20 to 110microg/m3 of lead (7439921), 110 to 800microg/m3 of zinc (7440666), and 3 to 14microg/m3 of total fumes. The data showed that the lowest total fume concentrations were found with tungsten inert gas welding and plasma welding which are both used for small welds. The authors listed recommended reduction factors ranging from one to greater than 100 for 16 welding practices that would result in a less than 10% chance that threshold limit values for substances typically encountered would be exceeded. They also state that these factors would be higher for confined spaces.","Exposure of Welders to Fumes and Gases in Dutch Industries: Summary of Results Abs: An extensive study of the exposure of welders to chemical and physical agents at the workplace and in the laboratory was described and the following types of welding were examined: manual metal arc, metal active gas, metal inert gas, tungsten inert gas, submerged arc, and flux cored arc. The air in the breathing zone of the welders behind the face shield was sampled during two 8 hour shifts by personal sampling. Two types of face shield were used, the hand held welding shield and the welding helmet. Samples were also collected at stationary test sites at a distance of about 2 meters from the welder. The total welding fume concentrations at the stationary test sites, although sampled in close vicinity to the welders, were appreciably less than those in the breathing zone. Welders working in a ship built of steel primed with a red iron/epoxy resin primer were exposed in the breathing zone to up to 12 parts per million (ppm) of carbon-monoxide (630080) (CO), up to 0.04ppm of formaldehyde (50000) and 5 to 50mg/m3 of total welding fumes. The corresponding results for welding of steel contaminated with oil, also in a ship, were 4 to 19ppm CO, 2 to 3 micrograms/m3 of polycyclic aromatic hydrocarbons, 35 to 150 nanograms/cubic meter of benzo(a)pyrene (50328), and 3 to 55mg/m3 of total welding fumes. In a large ventilated room, the gas flame cutting of steel treated with a primer containing lead and zinc chromates produced the following concentrations of pollutants in the breathing zone of the cutters: up to 17 micrograms per cubic meter (microg/m3) of chromium (7440473), 20 to 110microg/m3 of lead (7439921), 110 to 800microg/m3 of zinc (7440666), and 3 to 14microg/m3 of total fumes. The data showed that the lowest total fume concentrations were found with tungsten inert gas welding and plasma welding which are both used for small welds. The authors listed recommended reduction factors ranging from one to greater than 100 for 16 welding practices that would result in a less than 10% chance that threshold limit values for substances typically encountered would be exceeded. They also state that these factors would be higher for confined spaces."
1238273,Ryberg and  Alexander 1990,Mechanisms of chromium toxicity in mitochondria,"The mechanisms of chromium (7440473) toxicity in mitochondria were examined. Heart mitochondria obtained from Wistar-rats were incubated with 0 to 50 micromolar (microM) sodium-chromate (7775113) in the presence of NAD linked substrates such as beta-hydroxybutyrate (bOHBu), citrate, pyruvate, or succinate. The effects on mitochondrial respiration were determined by measuring oxygen consumption. A similar experiment was done with sonicated mitochondria with added NADH (58684). Mitochondrial respiration was inhibited by sodium-chromate when bOHBu, citrate, and pyruvate were used as substrates. Respiration was almost completely blocked by sodium-chromate when pyruvate was used as substrate. Respiration was not inhibited in the presence of succinate or with sonicated mitochondria and NADH. Rat heart mitochondria were preincubated with 0 or 10 millimolar (mM) pyruvate or 5microM rotenone (83794). This was followed by 30microM sodium-chromate. The concentrations of hexavalent-chromium (18540299) (Cr+6) and NADH were measured 0, 2, and 5 minutes after sodium-chromate. The concentration of NADH was significantly decreased 2 and 5 minutes after sodium-chromate was added. Cr+6 concentration was slightly decreased. Sodium-chromate at 100microM was reacted with 10mM vanadyl-sulfate (27774136) in the presence or absence of NADH. The stoichiometry of the reduction of Cr+6 to trivalent-chromium (16065831) (Cr+3) was determined. Three equivalents of vanadyl ion were required to reduce Cr+6 to Cr+3 in the absence of NADH. When NADH was present only one equivalent of vanadyl-ion was required. Intact mitochondria were incubated with sodium-chromate and the inhibition of mitochondrial citrate-synthase, isocitrate-dehydrogenase, alpha-keto-glutarate-dehydrogenase (KGDH), succinate-dehydrogenase, malate-dehydrogenase, pyruvate-dehydrogenase (PDH), glutamate-dehydrogenase, beta-hydroxybutyrate-dehydrogenase (bOHBDH), and keto-acyl-coenzyme-A-thiolase activities by sodium-chromate was measured. Only KGDH, PDH, and bOHBDH activities were inhibited. The sodium-chromate concentrations causing 50% inhibition were 3 to 5, 60 to 70, and 25 to 30microM, respectively. The authors conclude that chromate toxicity in mitochondria is probably due to NADH being depleted either as the result of oxidation by pentavalent-chromium or a decrease in its formation due to inhibition of enzymes such as KGDH.","Mechanisms of chromium toxicity in mitochondria Abs: The mechanisms of chromium (7440473) toxicity in mitochondria were examined. Heart mitochondria obtained from Wistar-rats were incubated with 0 to 50 micromolar (microM) sodium-chromate (7775113) in the presence of NAD linked substrates such as beta-hydroxybutyrate (bOHBu), citrate, pyruvate, or succinate. The effects on mitochondrial respiration were determined by measuring oxygen consumption. A similar experiment was done with sonicated mitochondria with added NADH (58684). Mitochondrial respiration was inhibited by sodium-chromate when bOHBu, citrate, and pyruvate were used as substrates. Respiration was almost completely blocked by sodium-chromate when pyruvate was used as substrate. Respiration was not inhibited in the presence of succinate or with sonicated mitochondria and NADH. Rat heart mitochondria were preincubated with 0 or 10 millimolar (mM) pyruvate or 5microM rotenone (83794). This was followed by 30microM sodium-chromate. The concentrations of hexavalent-chromium (18540299) (Cr+6) and NADH were measured 0, 2, and 5 minutes after sodium-chromate. The concentration of NADH was significantly decreased 2 and 5 minutes after sodium-chromate was added. Cr+6 concentration was slightly decreased. Sodium-chromate at 100microM was reacted with 10mM vanadyl-sulfate (27774136) in the presence or absence of NADH. The stoichiometry of the reduction of Cr+6 to trivalent-chromium (16065831) (Cr+3) was determined. Three equivalents of vanadyl ion were required to reduce Cr+6 to Cr+3 in the absence of NADH. When NADH was present only one equivalent of vanadyl-ion was required. Intact mitochondria were incubated with sodium-chromate and the inhibition of mitochondrial citrate-synthase, isocitrate-dehydrogenase, alpha-keto-glutarate-dehydrogenase (KGDH), succinate-dehydrogenase, malate-dehydrogenase, pyruvate-dehydrogenase (PDH), glutamate-dehydrogenase, beta-hydroxybutyrate-dehydrogenase (bOHBDH), and keto-acyl-coenzyme-A-thiolase activities by sodium-chromate was measured. Only KGDH, PDH, and bOHBDH activities were inhibited. The sodium-chromate concentrations causing 50% inhibition were 3 to 5, 60 to 70, and 25 to 30microM, respectively. The authors conclude that chromate toxicity in mitochondria is probably due to NADH being depleted either as the result of oxidation by pentavalent-chromium or a decrease in its formation due to inhibition of enzymes such as KGDH."
1238270,Garrison et al. 1990,"Changes in hepatocyte ploidy in response to chromium, analyzed by computer-assisted microscopy","BDF1 mice were given single injections of sodium dichromate (25 mg/kg) on an acute (6 hr to 7 days) or intermediate (2-4 weeks) basis, or multiple injections (12.5 mg/kg) on a chronic (4.5 months) basis. Observed hepatic changes included programmed cell death (apoptosis) in the periportal region with acute exposure and fusion of liver lobes with chronic exposure. Response to chromate exposure was measured by change in hepatocyte nuclear ploidy state (e.g., the proportion of diploid, tetraploid, and octaploid nuclei) based on computer-assisted imaging from histological sections. The computer-assisted imaging system used in this study was superior to traditional methods because it (1) allows rapid ploidy determinations from histological material and (2) can be used to collect regional information. Regional differences in ploidy were seen to occur in a consistent fashion among both control and treated animals. Nuclei adjacent to the portal triad had the lowest ploidy value (highest proportion of diploid nuclei), an intermediate value was found adjacent to the central vein, and the highest ploidy was found in the midzone. These three ploidy-based zones roughly correspond to the three functional zones of A. M. Rappaport (1973, Microvasc. Res. 6, 212-228) and W. H. Lamers et al. W. H. Lamers, A. Hilberts, E. Furt, J. Smith, G. N. Jonges, J. F. Van Noorden, J. W. G. Janzen, R. Charles, and A. F. M. Moorman, 1989, Hepatology, 10, 72-76. Temporal changes in ploidy were seen among control animals (all zones), with young animals (56 days) displaying relatively low ploidy values compared to older animals (184 days). Chromate exposure caused increased ploidy (all zones) among animals treated on an acute basis (the youngest animals). Chromate had no apparent effect on ploidy among animals treated for longer periods of time, probably because of age-related factors.","Changes in hepatocyte ploidy in response to chromium, analyzed by computer-assisted microscopy Abs: BDF1 mice were given single injections of sodium dichromate (25 mg/kg) on an acute (6 hr to 7 days) or intermediate (2-4 weeks) basis, or multiple injections (12.5 mg/kg) on a chronic (4.5 months) basis. Observed hepatic changes included programmed cell death (apoptosis) in the periportal region with acute exposure and fusion of liver lobes with chronic exposure. Response to chromate exposure was measured by change in hepatocyte nuclear ploidy state (e.g., the proportion of diploid, tetraploid, and octaploid nuclei) based on computer-assisted imaging from histological sections. The computer-assisted imaging system used in this study was superior to traditional methods because it (1) allows rapid ploidy determinations from histological material and (2) can be used to collect regional information. Regional differences in ploidy were seen to occur in a consistent fashion among both control and treated animals. Nuclei adjacent to the portal triad had the lowest ploidy value (highest proportion of diploid nuclei), an intermediate value was found adjacent to the central vein, and the highest ploidy was found in the midzone. These three ploidy-based zones roughly correspond to the three functional zones of A. M. Rappaport (1973, Microvasc. Res. 6, 212-228) and W. H. Lamers et al. W. H. Lamers, A. Hilberts, E. Furt, J. Smith, G. N. Jonges, J. F. Van Noorden, J. W. G. Janzen, R. Charles, and A. F. M. Moorman, 1989, Hepatology, 10, 72-76. Temporal changes in ploidy were seen among control animals (all zones), with young animals (56 days) displaying relatively low ploidy values compared to older animals (184 days). Chromate exposure caused increased ploidy (all zones) among animals treated on an acute basis (the youngest animals). Chromate had no apparent effect on ploidy among animals treated for longer periods of time, probably because of age-related factors."
1238264,Heitbrink and  O'Brien 1989,Exposure Estimation Procedure for Powder Handling Operations Based on Dustiness Testing,"A dustiness test result may be an indication of the dustiness of a given material and may be used to evaluate the dust exposure potential of powders undergoing a Premanufacturing Notice (PMN) review. A correlation between dust exposures and the Midwest Research Institute (MRI) dustiness test was evaluated for use in estimating the dust exposure potential of new powders undergoing PMN review. The exposure estimation procedure was based on dustiness test results because of difficulties in estimating from physical parameters. The data for the correlation were obtained at one bag filling operation at a plastic resin facility and at a bag filling and bag packing operation at a lead-chromate (7758976) facility. The correlation between worker dust exposure and dustiness as measured by the MRI and the Heubach dustiness tests was evaluated. The MRI dustiness test data and the worker exposure data were combined into a single data set containing 75 data points. The information suggested that reducing the dustiness below about 30, as measured by the MRI dustiness index, does not result in further reduction of worker dust exposure. For facilities with reasonable engineering controls and process equipment, the logic derived in this report will probably result in overestimates of worker dust exposures.","Exposure Estimation Procedure for Powder Handling Operations Based on Dustiness Testing Abs: A dustiness test result may be an indication of the dustiness of a given material and may be used to evaluate the dust exposure potential of powders undergoing a Premanufacturing Notice (PMN) review. A correlation between dust exposures and the Midwest Research Institute (MRI) dustiness test was evaluated for use in estimating the dust exposure potential of new powders undergoing PMN review. The exposure estimation procedure was based on dustiness test results because of difficulties in estimating from physical parameters. The data for the correlation were obtained at one bag filling operation at a plastic resin facility and at a bag filling and bag packing operation at a lead-chromate (7758976) facility. The correlation between worker dust exposure and dustiness as measured by the MRI and the Heubach dustiness tests was evaluated. The MRI dustiness test data and the worker exposure data were combined into a single data set containing 75 data points. The information suggested that reducing the dustiness below about 30, as measured by the MRI dustiness index, does not result in further reduction of worker dust exposure. For facilities with reasonable engineering controls and process equipment, the logic derived in this report will probably result in overestimates of worker dust exposures."
1238262,Kiec-Swierczynska 1989,"Comparison of Risk of Occupational Dermatoses and Allergy to Metals in Workers Employed in Plants Manufacturing Prefabricated Building Products Made of Ordinary Concrete, Cellular Concrete and Asbestos Cement","A study of the prevalence of occupational dermatoses in 1429 Polish construction industry workers, 1308 males, exposed to chromium (7440473), cobalt (7440484), and nickel (7440020) in prefabricated construction materials made of cement, flyash, and asbestos (1332214) cement was conducted. A total of 905 workers were employed in manufacturing prefabricated cement products, 252 workers manufactured flyash containing products, 157 workers manufactured products containing flyash and cement, and 178 workers manufactured asbestos, mineral wool, and cement products. Skin examinations that included patch testing with potassium-dichromate (7778509), cobalt-chloride (7646799), and nickel-sulfate (7786814) were performed. The building materials were analyzed for chromium, cobalt, and nickel. A total of 360 subjects (24.1%) had work related dermatitis, 189 (12.7%) had oil acne, and 469 had dermatoses of nonoccupational origin. Dermatitis was primarily on the hands and occasionally on the forearms and faces of persons exposed to mineral wool and asbestos cement. Oil acne was found primarily in males and on parts of the body exposed to oils and greases impregnating protective clothing. Dermatitis occurred primarily in workers exposed to cement. A total of 339 subjects had an allergic reaction to chromium, 210 to cobalt, and 39 to nickel. The prevalence of nickel hypersensitivity in females was five times that in males. The prevalence of chromium allergy was significantly greater in persons exposed to flyash and asbestos cement. The prevalence of nickel and cobalt allergy did not vary significantly with construction material type. The highest concentrations of chromium were found in asbestos and mineral wool products. The highest concentrations of cobalt occurred in asbestos, wool, and flyash containing products. The highest nickel concentrations were found in nickel containing products. The highest concentrations of soluble (hexavalent) chromium compounds were found in cement.","Comparison of Risk of Occupational Dermatoses and Allergy to Metals in Workers Employed in Plants Manufacturing Prefabricated Building Products Made of Ordinary Concrete, Cellular Concrete and Asbestos Cement Abs: A study of the prevalence of occupational dermatoses in 1429 Polish construction industry workers, 1308 males, exposed to chromium (7440473), cobalt (7440484), and nickel (7440020) in prefabricated construction materials made of cement, flyash, and asbestos (1332214) cement was conducted. A total of 905 workers were employed in manufacturing prefabricated cement products, 252 workers manufactured flyash containing products, 157 workers manufactured products containing flyash and cement, and 178 workers manufactured asbestos, mineral wool, and cement products. Skin examinations that included patch testing with potassium-dichromate (7778509), cobalt-chloride (7646799), and nickel-sulfate (7786814) were performed. The building materials were analyzed for chromium, cobalt, and nickel. A total of 360 subjects (24.1%) had work related dermatitis, 189 (12.7%) had oil acne, and 469 had dermatoses of nonoccupational origin. Dermatitis was primarily on the hands and occasionally on the forearms and faces of persons exposed to mineral wool and asbestos cement. Oil acne was found primarily in males and on parts of the body exposed to oils and greases impregnating protective clothing. Dermatitis occurred primarily in workers exposed to cement. A total of 339 subjects had an allergic reaction to chromium, 210 to cobalt, and 39 to nickel. The prevalence of nickel hypersensitivity in females was five times that in males. The prevalence of chromium allergy was significantly greater in persons exposed to flyash and asbestos cement. The prevalence of nickel and cobalt allergy did not vary significantly with construction material type. The highest concentrations of chromium were found in asbestos and mineral wool products. The highest concentrations of cobalt occurred in asbestos, wool, and flyash containing products. The highest nickel concentrations were found in nickel containing products. The highest concentrations of soluble (hexavalent) chromium compounds were found in cement."
1238261,Matczak and  Chmielnicka 1989,Methods for Determining Soluble and Insoluble Cr III and Cr VI Compounds in Welding Fumes,"A method for determining soluble and insoluble trivalent (Cr+3) and hexavalent (Cr+6) chromium (7440473) in welding fumes was developed. Welding fume samples were collected on membrane and glass filters. The membrane filters were dissolved in concentrated nitric-acid and diluted with 10% nitric-acid. The solutions were analyzed for total chromium by atomic absorption spectrophotometry (AAS). The glass filters were extracted with water. The extracts were analyzed for total chromium by AAS. A portion of the water extracts was passed through a diphenylcarbazide column. The eluate contained Cr+3 only. The eluate was analyzed for Cr+3 by AAS. The residue remaining after water extraction was divided into two parts. One portion was dissolved in concentrated nitric-acid. This sample, which represented total insoluble chromium, was analyzed by AAS. The second portion of the residue underwent alkaline extraction. The extract was treated with S-diphenylcarbazide. The reaction product was analyzed for total Cr+6 by a colorimetric procedure. The concentrations of soluble and insoluble Cr+6 and total and insoluble Cr+3 could be calculated from the data. When the method was used to analyze filters spiked with 0.16 milligram (mg) chromic-chloride (10025737), 0.48mg potassium-dichromate (7778509), and 0.16mg lead-chromate (7758976), recoveries exceeded 80% and the relative standard deviations in the measured chromium species were around 20%. The method was used to determine the concentrations of the various chromium species in the breathing zone of arc welders welding stainless steel or mild steel. Total chromium concentrations ranged from 2.4 to 4.2%. The relative amounts of total Cr+6 and Cr+3 were 66 and 34%, respectively. Approximately 66% of the total chromium content of the fumes was soluble chromium and 34% insoluble chromium. Among the soluble chromium species, 20% was Cr+3 and 45% Cr+6. Approximately 14% of the insoluble chromium species was Cr+3 and 20% Cr+6. Considerable error occurred in determining the concentration of insoluble Cr+6 since it was calculated by difference. The authors conclude that Cr+6 is the major species in the chromium content of welding fumes.","Methods for Determining Soluble and Insoluble Cr III and Cr VI Compounds in Welding Fumes Abs: A method for determining soluble and insoluble trivalent (Cr+3) and hexavalent (Cr+6) chromium (7440473) in welding fumes was developed. Welding fume samples were collected on membrane and glass filters. The membrane filters were dissolved in concentrated nitric-acid and diluted with 10% nitric-acid. The solutions were analyzed for total chromium by atomic absorption spectrophotometry (AAS). The glass filters were extracted with water. The extracts were analyzed for total chromium by AAS. A portion of the water extracts was passed through a diphenylcarbazide column. The eluate contained Cr+3 only. The eluate was analyzed for Cr+3 by AAS. The residue remaining after water extraction was divided into two parts. One portion was dissolved in concentrated nitric-acid. This sample, which represented total insoluble chromium, was analyzed by AAS. The second portion of the residue underwent alkaline extraction. The extract was treated with S-diphenylcarbazide. The reaction product was analyzed for total Cr+6 by a colorimetric procedure. The concentrations of soluble and insoluble Cr+6 and total and insoluble Cr+3 could be calculated from the data. When the method was used to analyze filters spiked with 0.16 milligram (mg) chromic-chloride (10025737), 0.48mg potassium-dichromate (7778509), and 0.16mg lead-chromate (7758976), recoveries exceeded 80% and the relative standard deviations in the measured chromium species were around 20%. The method was used to determine the concentrations of the various chromium species in the breathing zone of arc welders welding stainless steel or mild steel. Total chromium concentrations ranged from 2.4 to 4.2%. The relative amounts of total Cr+6 and Cr+3 were 66 and 34%, respectively. Approximately 66% of the total chromium content of the fumes was soluble chromium and 34% insoluble chromium. Among the soluble chromium species, 20% was Cr+3 and 45% Cr+6. Approximately 14% of the insoluble chromium species was Cr+3 and 20% Cr+6. Considerable error occurred in determining the concentration of insoluble Cr+6 since it was calculated by difference. The authors conclude that Cr+6 is the major species in the chromium content of welding fumes."
1238257,Leonard and  Gerber 1989,Zinc Toxicity: Does it Exist?,"The question of whether zinc (7440666) is toxic was discussed and the biological function of zinc was summarized. Investigations of zinc mutagenicity were also described and have indicated that zinc does not appear to be mutagenic in most assays that measure DNA damage. The positive responses noted in investigations where zinc containing pesticides and zinc chromates were tested were attributed to the effect of the organic constituents and the chromate ion, respectively. Chromosome aberrations observed in some workers in the zinc industry were considered to be due to mutagenic factors other than zinc in the work environment. Bone marrow abnormalities observed in mice fed 0.5 percent zinc were attributed to the animals being fed a calcium deficient diet. It was noted that zinc deficient diets can produce chromosome aberrations. Investigations on zinc carcinogenicity have indicated that zinc is not carcinogenic, although tissue zinc concentrations may influence tumor growth under conditions where an overt or latent zinc deficiency exists. Zinc has been thought to inhibit cancer induction by a variety of carcinogens. Investigations of zinc teratogenicity were discussed. Zinc deficiency has been observed to impair reproductive ability. A high rate of malformations was induced in the offspring of rats maintained on zinc deficient diets. None of the investigations have demonstrated a teratogenic response resulting from excess zinc intake. Investigations in rats given EDTA and zinc have indicated that zinc may protect against the teratogenic effect induced by EDTA.","Zinc Toxicity: Does it Exist? Abs: The question of whether zinc (7440666) is toxic was discussed and the biological function of zinc was summarized. Investigations of zinc mutagenicity were also described and have indicated that zinc does not appear to be mutagenic in most assays that measure DNA damage. The positive responses noted in investigations where zinc containing pesticides and zinc chromates were tested were attributed to the effect of the organic constituents and the chromate ion, respectively. Chromosome aberrations observed in some workers in the zinc industry were considered to be due to mutagenic factors other than zinc in the work environment. Bone marrow abnormalities observed in mice fed 0.5 percent zinc were attributed to the animals being fed a calcium deficient diet. It was noted that zinc deficient diets can produce chromosome aberrations. Investigations on zinc carcinogenicity have indicated that zinc is not carcinogenic, although tissue zinc concentrations may influence tumor growth under conditions where an overt or latent zinc deficiency exists. Zinc has been thought to inhibit cancer induction by a variety of carcinogens. Investigations of zinc teratogenicity were discussed. Zinc deficiency has been observed to impair reproductive ability. A high rate of malformations was induced in the offspring of rats maintained on zinc deficient diets. None of the investigations have demonstrated a teratogenic response resulting from excess zinc intake. Investigations in rats given EDTA and zinc have indicated that zinc may protect against the teratogenic effect induced by EDTA."
1238253,Langard 1989,Basic Mechanisms of the Carcinogenic Action of Chromium: Animal and Human Data,"A review of human and animal investigations on the mechanisms of chromium (7440473) carcinogenicity was presented. Factors influencing the uptake of chromium from chromium(VI) containing particulate or droplet aerosols were described. Investigations have indicated that the bronchial tree is most important for uptake and carcinogenic action of chromium(VI). Investigations linking exposure to chromates to cancer in humans were summarized. Zinc-chromate (15930946) and calcium-chromate (13765190) were well documented human carcinogens. Reduction of chromium(VI) to chromium(III) by pulmonary alveolar macrophages, red blood cells, and intracellular reduction/oxidation systems were protective mechanisms. Exposure to chromium(III) compounds was not linked to increased cancer incidence in epidemiological investigations. In laboratory animals, intramuscular administration of calcium-chromate, strontium-chromate (7789062), or lead-chromate (7758976) was associated with development of implantation site sarcomas. The author concludes that chromates are more potent carcinogens in humans than in animals and recommends a number of areas deserving further investigation.","Basic Mechanisms of the Carcinogenic Action of Chromium: Animal and Human Data Abs: A review of human and animal investigations on the mechanisms of chromium (7440473) carcinogenicity was presented. Factors influencing the uptake of chromium from chromium(VI) containing particulate or droplet aerosols were described. Investigations have indicated that the bronchial tree is most important for uptake and carcinogenic action of chromium(VI). Investigations linking exposure to chromates to cancer in humans were summarized. Zinc-chromate (15930946) and calcium-chromate (13765190) were well documented human carcinogens. Reduction of chromium(VI) to chromium(III) by pulmonary alveolar macrophages, red blood cells, and intracellular reduction/oxidation systems were protective mechanisms. Exposure to chromium(III) compounds was not linked to increased cancer incidence in epidemiological investigations. In laboratory animals, intramuscular administration of calcium-chromate, strontium-chromate (7789062), or lead-chromate (7758976) was associated with development of implantation site sarcomas. The author concludes that chromates are more potent carcinogens in humans than in animals and recommends a number of areas deserving further investigation."
1238250,Bronzetti and  Galli 1989,Influence of NTA on the chromium genotoxicity,"The effect of nitrilotriacetic-acid (139139) (NTA) on chromium (7440473) genotoxicity was examined. Cultures of the D7 strain of Saccharomyces-cerevisiae were incubated with 0, 5, or 25 millimolar (mM) sodium-chromate plus 0, 5, 6.25, 12.5, 25, or 50mM NTA or 0 or 1mM chromic-chloride (10025737) plus 0, 0.5, 1, or 2mM NTA. Genotoxicity was evaluated by assaying the cultures for mitotic gene conversion and point mutations. Cytotoxicity was assessed by determining survival. Sodium-chromate at 25mM induced both mitotic gene conversion and point mutations. Chromic-chloride alone did not induce any genotoxic effects. Sodium-chromate at 5mM plus NTA increased the frequency of point mutations without affecting mitotic gene conversion. Sodium-chromate at 25mM plus NTA caused a decrease in the frequency of gene conversion without affecting the frequency of point mutations. NTA decreased the cytotoxicity of chromic-chloride. Chromic-chloride plus 2mM NTA caused a significant increase in the frequency of point mutations and a nonsignificant increase in gene conversion frequency. The authors suggest that at low doses of sodium-chromate NTA may act synergistically with the chromate to promate reduction of hexavalent-chromium (18540299) (Cr+6) to trivalent-chromium (16065831) (Cr+3). At higher doses NTA may alter the mechanism of recombination DNA repair of DNA breaks induced by Cr+6. NTA may interact directly with Cr+3 ions to form complexes that can cross the cellular membrane to bind to DNA.","Influence of NTA on the chromium genotoxicity Abs: The effect of nitrilotriacetic-acid (139139) (NTA) on chromium (7440473) genotoxicity was examined. Cultures of the D7 strain of Saccharomyces-cerevisiae were incubated with 0, 5, or 25 millimolar (mM) sodium-chromate plus 0, 5, 6.25, 12.5, 25, or 50mM NTA or 0 or 1mM chromic-chloride (10025737) plus 0, 0.5, 1, or 2mM NTA. Genotoxicity was evaluated by assaying the cultures for mitotic gene conversion and point mutations. Cytotoxicity was assessed by determining survival. Sodium-chromate at 25mM induced both mitotic gene conversion and point mutations. Chromic-chloride alone did not induce any genotoxic effects. Sodium-chromate at 5mM plus NTA increased the frequency of point mutations without affecting mitotic gene conversion. Sodium-chromate at 25mM plus NTA caused a decrease in the frequency of gene conversion without affecting the frequency of point mutations. NTA decreased the cytotoxicity of chromic-chloride. Chromic-chloride plus 2mM NTA caused a significant increase in the frequency of point mutations and a nonsignificant increase in gene conversion frequency. The authors suggest that at low doses of sodium-chromate NTA may act synergistically with the chromate to promate reduction of hexavalent-chromium (18540299) (Cr+6) to trivalent-chromium (16065831) (Cr+3). At higher doses NTA may alter the mechanism of recombination DNA repair of DNA breaks induced by Cr+6. NTA may interact directly with Cr+3 ions to form complexes that can cross the cellular membrane to bind to DNA."
1238249,Wolf et al. 1989,Different molecular effects on nucleotides by interaction with Cr(III) and Cr(VI): A 31P-NMR study in vitro,"In 1962 Eisinger and coworkers first postulated an interaction of Cr(III) with the phosphate groups of native DNA (J. Eisinger et al., J. Chem. Phys. 36, 1721, 1962). As an indicator for the strength of the molecular interaction between Cr(III) and the phosphate groups in DNA, Eisinger measured the proton relaxation time. Weser in 1968 showed a direct interaction between Mn(II) and Cu(II) and the phosphate groups of ATP by use of phosphorus magnetic resonance spectroscopy (U. Weser, Structure and Bonding 5, 41, 1968). With proton magnetic resonance spectroscopy he demonstrated an interaction of the N?7 position in AMP and ATP with Cu(II). Similar results were obtained by Eichhorn and coworkers (G. L. Eichhorn et al., Adv. Chem. Series 100, 135, 1971). Furthermore, Eichhorn substituted the N?7 of purine monophosphate nucleotides against carbon resulting in no interaction with copper ions. In our study we used 31?P?NMR spectroscopy to elucidate the molecular interaction of Cr(III) and Cr(VI) ions with CTP, GTP, GDP, ATP, ADP, dATP. We choose the interaction of Mg(II) and ATP as reference for a metal ion interaction with a phosphorus?containing nucleotide. Only Cr(III) compounds showed concentration dependent interactions of the metal ion with the phosphate groups. These effects were characterized by differential downfield shifts and signal broadening for the alpha, beta? and gamma?phosphate groups which could only be explained by interaction of Cr(III). The paramagnetic influence of Cr(III) alone would result in an homologous downfield shift and signal broadening for all three phosphate groups. In contrast, none of these interactions could be found with Cr(VI). In contrast, none of these interactions could be found with Cr(VI). These results are therefore consistent with the concept that only Cr(III) compounds ultimately interact with DNA.","Different molecular effects on nucleotides by interaction with Cr(III) and Cr(VI): A 31P-NMR study in vitro Abs: In 1962 Eisinger and coworkers first postulated an interaction of Cr(III) with the phosphate groups of native DNA (J. Eisinger et al., J. Chem. Phys. 36, 1721, 1962). As an indicator for the strength of the molecular interaction between Cr(III) and the phosphate groups in DNA, Eisinger measured the proton relaxation time. Weser in 1968 showed a direct interaction between Mn(II) and Cu(II) and the phosphate groups of ATP by use of phosphorus magnetic resonance spectroscopy (U. Weser, Structure and Bonding 5, 41, 1968). With proton magnetic resonance spectroscopy he demonstrated an interaction of the N?7 position in AMP and ATP with Cu(II). Similar results were obtained by Eichhorn and coworkers (G. L. Eichhorn et al., Adv. Chem. Series 100, 135, 1971). Furthermore, Eichhorn substituted the N?7 of purine monophosphate nucleotides against carbon resulting in no interaction with copper ions. In our study we used 31?P?NMR spectroscopy to elucidate the molecular interaction of Cr(III) and Cr(VI) ions with CTP, GTP, GDP, ATP, ADP, dATP. We choose the interaction of Mg(II) and ATP as reference for a metal ion interaction with a phosphorus?containing nucleotide. Only Cr(III) compounds showed concentration dependent interactions of the metal ion with the phosphate groups. These effects were characterized by differential downfield shifts and signal broadening for the alpha, beta? and gamma?phosphate groups which could only be explained by interaction of Cr(III). The paramagnetic influence of Cr(III) alone would result in an homologous downfield shift and signal broadening for all three phosphate groups. In contrast, none of these interactions could be found with Cr(VI). In contrast, none of these interactions could be found with Cr(VI). These results are therefore consistent with the concept that only Cr(III) compounds ultimately interact with DNA."
1238247,Cavelier et al. 1989,Allergy to Nickel or Cobalt: Tolerance to Nickel and Cobalt Samples in Man and in the Guinea Pig Allergic or Sensitized to these Metals,"Tolerance to nickel (7440020) and cobalt (7440484) was studied in previously sensitized guinea-pigs and humans. Female Hartley-guinea-pigs previously sensitized to nickel-sulfate (7786814) or cobalt-chloride (7646799) were treated with patches containing cobalt or nickel in lanolin. The metal samples were prepared by various metallurgical processes and in some cases were plated with chromium (7440473) or copper/chromium alloy. The patches were kept in place for 48 hours. One or 24 hours after they were removed the treated skin was graded for erythema and edema. Biopsy samples were taken for histopathological examination. Thirteen patients allergic to nickel, cobalt, or chromium were tested with cobalt-chloride, potassium-chromate (7789006), nickel-sulfate, or the metals as before. The treated areas were evaluated for erythema and edema 48 hours later. Guinea-pigs sensitized to either nickel or cobalt were intolerant to both metals, as evidenced by varying degrees of erythema and edema developing. The biopsy samples showed an eczematous reaction. The chromium or copper/chromium plated metals induced the same reaction. All patients allergic to nickel tolerated metallic cobalt except a nickel/cobalt alloy and a mixture of matt cobalt and chromium. Patients allergic to cobalt or to more than one metal were generally intolerant to all metals. The authors conclude that cobalt and nickel sensitized guinea-pigs are cross sensitized to these metals. Tolerance to metals in humans varies with the individual sensitivity. The reason for the differences in metal sensitivity between guinea-pigs and humans is not understood.","Allergy to Nickel or Cobalt: Tolerance to Nickel and Cobalt Samples in Man and in the Guinea Pig Allergic or Sensitized to these Metals Abs: Tolerance to nickel (7440020) and cobalt (7440484) was studied in previously sensitized guinea-pigs and humans. Female Hartley-guinea-pigs previously sensitized to nickel-sulfate (7786814) or cobalt-chloride (7646799) were treated with patches containing cobalt or nickel in lanolin. The metal samples were prepared by various metallurgical processes and in some cases were plated with chromium (7440473) or copper/chromium alloy. The patches were kept in place for 48 hours. One or 24 hours after they were removed the treated skin was graded for erythema and edema. Biopsy samples were taken for histopathological examination. Thirteen patients allergic to nickel, cobalt, or chromium were tested with cobalt-chloride, potassium-chromate (7789006), nickel-sulfate, or the metals as before. The treated areas were evaluated for erythema and edema 48 hours later. Guinea-pigs sensitized to either nickel or cobalt were intolerant to both metals, as evidenced by varying degrees of erythema and edema developing. The biopsy samples showed an eczematous reaction. The chromium or copper/chromium plated metals induced the same reaction. All patients allergic to nickel tolerated metallic cobalt except a nickel/cobalt alloy and a mixture of matt cobalt and chromium. Patients allergic to cobalt or to more than one metal were generally intolerant to all metals. The authors conclude that cobalt and nickel sensitized guinea-pigs are cross sensitized to these metals. Tolerance to metals in humans varies with the individual sensitivity. The reason for the differences in metal sensitivity between guinea-pigs and humans is not understood."
1238245,Wolf et al. 1989,Nick Translation Studies on DNA Strand Breaks in pBR322 Plasmid Induced by Different Chromium Species,"The ability of hexavalent-chromium (18540299) (Cr+6) to induce DNA strand breaks was studied in-vitro. Aqueous plasmid pBR322 DNA was incubated with 0 or 100 picomole potassium-dichromate (7778509) or chromium(III)-nitrate (13548384) in the presence or absence of 200 nanomoles (nmol) glutathione (GSH), 9.8 micromoles or 980nmol hydrogen-peroxide, or 1 microgram superoxide-dismutase (SOD). In some experiments, deuterium-oxide was substituted for water. The samples were assayed for DNA single strand breaks utilizing DNA agarose gel electrophoresis and a nick translation assay. DNA single strand breaks could only be detected in systems incubated with Cr+6 plus hydrogen-peroxide. The breaks occurred in systems containing either water or deuterium-oxide. No strand breaks occurred in systems containing Cr+6 in water which were subsequently treated with SOD. The authors conclude that Cr+6 is able to induce DNA strand breaks only when it is reduced by hydrogen-peroxide. The reactive intermediate produced by the reaction of Cr+6 and hydrogen-peroxide is abolished by SOD. No strand breaks are induced by Cr+6 that is reduced by GSH. The authors suggest that superoxide anions and hydroxyl radicals produced by peroxochromium(V) species are the reactive species responsible for the genotoxic effects of Cr+6.","Nick Translation Studies on DNA Strand Breaks in pBR322 Plasmid Induced by Different Chromium Species Abs: The ability of hexavalent-chromium (18540299) (Cr+6) to induce DNA strand breaks was studied in-vitro. Aqueous plasmid pBR322 DNA was incubated with 0 or 100 picomole potassium-dichromate (7778509) or chromium(III)-nitrate (13548384) in the presence or absence of 200 nanomoles (nmol) glutathione (GSH), 9.8 micromoles or 980nmol hydrogen-peroxide, or 1 microgram superoxide-dismutase (SOD). In some experiments, deuterium-oxide was substituted for water. The samples were assayed for DNA single strand breaks utilizing DNA agarose gel electrophoresis and a nick translation assay. DNA single strand breaks could only be detected in systems incubated with Cr+6 plus hydrogen-peroxide. The breaks occurred in systems containing either water or deuterium-oxide. No strand breaks occurred in systems containing Cr+6 in water which were subsequently treated with SOD. The authors conclude that Cr+6 is able to induce DNA strand breaks only when it is reduced by hydrogen-peroxide. The reactive intermediate produced by the reaction of Cr+6 and hydrogen-peroxide is abolished by SOD. No strand breaks are induced by Cr+6 that is reduced by GSH. The authors suggest that superoxide anions and hydroxyl radicals produced by peroxochromium(V) species are the reactive species responsible for the genotoxic effects of Cr+6."
1238242,Gava et al. 1989,Induction of gene mutations in Salmonella and Drosophila by soluble Cr(VI) compounds: Synergistic effects of nitrilotriacetic acid,"The interaction between NTA and soluble Cr(VI) (K2Cr2O7) was studied by the Ames test on S. typhimurium and the sex?linked recessive lethal test on D. melanogaster. In both systems a synergistic effect of NTA on Cr(VI) mutagenicity took place at sub?toxic doses of Cr(VI). The synergism could depend on the action of NTA on intracellular Cr(VI) reduction, as more Cr(VI) was reduced in vitro to Cr(III) by Salmonella and Drosophila protein extracts in the presence of NTA. A similar enhancement of soluble Cr(VI) mutagenicity was produced by low doses of EDTA.","Induction of gene mutations in Salmonella and Drosophila by soluble Cr(VI) compounds: Synergistic effects of nitrilotriacetic acid Abs: The interaction between NTA and soluble Cr(VI) (K2Cr2O7) was studied by the Ames test on S. typhimurium and the sex?linked recessive lethal test on D. melanogaster. In both systems a synergistic effect of NTA on Cr(VI) mutagenicity took place at sub?toxic doses of Cr(VI). The synergism could depend on the action of NTA on intracellular Cr(VI) reduction, as more Cr(VI) was reduced in vitro to Cr(III) by Salmonella and Drosophila protein extracts in the presence of NTA. A similar enhancement of soluble Cr(VI) mutagenicity was produced by low doses of EDTA."
1238232,Cooper et al. 1989,"Study Report: Evaluation of Dustiness Test Methods and Recommendations for Improved Dust Control at Heubach Inc., Newark, New Jersey. Report No. CT-154-11a","A study was made of methods in place at the Heubach Inc. (SIC-2816, SIC-2865) facilities located in Newark, New Jersey, for the control of dust during the production of inorganic lead-chromate and organic pigments. This study centered in the packaging, bag filling, area of a particular building and in the bag emptying area of a second building. A 15 year old St. Regis force flow packer and a 20 year old St. Regis auger packer were used to package pigment in multiple paper bags in 50 pound quantities. In the bag emptying area semibulk or sling type bags, fiber drums, and 50 pound paper bags were emptied at one of five dump stations. A number of practices were used by this company to reduce worker dust exposures. These included product modification, process equipment design, local exhaust ventilation, personal protective equipment, and administrative controls. Some of the lead (7439921) pigments have been modified by using a proprietary additive to reduce their dustiness. Other equipment controls were discussed. Personal protective equipment was provided in the form of respiratory equipment, hearing protective devices, rubber gloves, hard hats, plastic aprons, regular and disposable coveralls, underwear, socks and shoes. Each employee viewed a 90 minute video on safety once a year, and the importance of good hygiene was stressed. Also discussed in this report was an evaluation of the dustiness test procedures and the correlation of the worker exposure with the dustiness test results. The authors recommend improved process design, ventilation and work practices for reducing lead exposures.","Study Report: Evaluation of Dustiness Test Methods and Recommendations for Improved Dust Control at Heubach Inc., Newark, New Jersey. Report No. CT-154-11a Abs: A study was made of methods in place at the Heubach Inc. (SIC-2816, SIC-2865) facilities located in Newark, New Jersey, for the control of dust during the production of inorganic lead-chromate and organic pigments. This study centered in the packaging, bag filling, area of a particular building and in the bag emptying area of a second building. A 15 year old St. Regis force flow packer and a 20 year old St. Regis auger packer were used to package pigment in multiple paper bags in 50 pound quantities. In the bag emptying area semibulk or sling type bags, fiber drums, and 50 pound paper bags were emptied at one of five dump stations. A number of practices were used by this company to reduce worker dust exposures. These included product modification, process equipment design, local exhaust ventilation, personal protective equipment, and administrative controls. Some of the lead (7439921) pigments have been modified by using a proprietary additive to reduce their dustiness. Other equipment controls were discussed. Personal protective equipment was provided in the form of respiratory equipment, hearing protective devices, rubber gloves, hard hats, plastic aprons, regular and disposable coveralls, underwear, socks and shoes. Each employee viewed a 90 minute video on safety once a year, and the importance of good hygiene was stressed. Also discussed in this report was an evaluation of the dustiness test procedures and the correlation of the worker exposure with the dustiness test results. The authors recommend improved process design, ventilation and work practices for reducing lead exposures."
1238231,Das et al. 1989,Chronic Chromium Poisoning with Dermatitis in the Leather Industry,"The case history of a 35 year old male tannery worker complaining of skin lesions of 6 months duration was presented. The patient had worked in the vegetable tanning section for 9 years and then had been transferred to the chrome tanning section after the development of greenish tinged callosities on both shoulders. In the chrome tanning section, where he treated hides with basic chromium-sulfate (10101538), the solution spilled on his legs to about 10 centimeters above each ankle. Itchy macules appeared anteriorly on both legs above the ankles. Pustules the size of a pinhead with some erythema and scaling circumscribed an area up to 10 centimeters above the ankles. Blood analysis demonstrated microcytic hypochromic anemia, with mild anisocytosis and poikilocytosis with a raised ESR. Patch testing indicated a positive reaction to potassium-dichromate (7778509). Psychotoxicological tests indicated poor hand eye coordination, vigilance and visuomotor ability. The authors conclude that continued exposure of the skin to a high concentration of chromium in solution had caused contact dermatitis, blood dyscrasia, hepatomegaly, mild renal impairment and psychological symptoms, resulting in the diagnosis of chronic chromium poisoning with dermatitis. The patient was educated as to the probable cause of his condition and instructed to change jobs. His dermatitis decreased with 1 percent aluminum-acetate solution treatment and oral antibiotics, followed by topical antibiotic and antiallergic treatment.","Chronic Chromium Poisoning with Dermatitis in the Leather Industry Abs: The case history of a 35 year old male tannery worker complaining of skin lesions of 6 months duration was presented. The patient had worked in the vegetable tanning section for 9 years and then had been transferred to the chrome tanning section after the development of greenish tinged callosities on both shoulders. In the chrome tanning section, where he treated hides with basic chromium-sulfate (10101538), the solution spilled on his legs to about 10 centimeters above each ankle. Itchy macules appeared anteriorly on both legs above the ankles. Pustules the size of a pinhead with some erythema and scaling circumscribed an area up to 10 centimeters above the ankles. Blood analysis demonstrated microcytic hypochromic anemia, with mild anisocytosis and poikilocytosis with a raised ESR. Patch testing indicated a positive reaction to potassium-dichromate (7778509). Psychotoxicological tests indicated poor hand eye coordination, vigilance and visuomotor ability. The authors conclude that continued exposure of the skin to a high concentration of chromium in solution had caused contact dermatitis, blood dyscrasia, hepatomegaly, mild renal impairment and psychological symptoms, resulting in the diagnosis of chronic chromium poisoning with dermatitis. The patient was educated as to the probable cause of his condition and instructed to change jobs. His dermatitis decreased with 1 percent aluminum-acetate solution treatment and oral antibiotics, followed by topical antibiotic and antiallergic treatment."
1238230,Guberan et al. 1989,"Disability, Mortality, and Incidence of Cancer among Geneva Painters and Electricians: A Historical Prospective Study","A study was conducted to examine the incidence of neuropsychiatric disability among painters in comparison to electricians in Geneva, Switzerland. The study was extended to the analysis of mortality and incidence of cancer among both groups. The cohorts included 1916 painters and 1948 electricians who were resident in the Canton of Geneva at the 1970 census. The painters were followed up for 14 years and a review of the causes of the 254 deaths and 121 disability pensions gave no case of presenile dementia. However, the higher incidence of disability among painters than among electricians may have resulted from the chronic effects of solvent exposure. Even so, in this study, solvent exposure was confounded with alcoholism which was associated with neuropsychiatric disease in 12 of 20 painters and only one of ten electricians. The authors conclude that there was not sufficient evidence to support the existence of a solvent related painters' syndrome. A highly significant excess of lung cancer among painters was possibly related to occupational exposure to asbestos (1332214) and zinc-chromate (13530659). An increased risk of biliary tract cancer and bladder cancer was noted in the painters and five cases of testicular cancer were found when 1.6 would have been expected. Risk for cerebrovascular disease was supported by the disability study which showed eight cases among painters and none among electricians. No significant excess of cancer was found for any specific site among electricians. The numbers were too small to adequately assess possible links between working as an electrician and the incidence of leukemia or brain tumor.","Disability, Mortality, and Incidence of Cancer among Geneva Painters and Electricians: A Historical Prospective Study Abs: A study was conducted to examine the incidence of neuropsychiatric disability among painters in comparison to electricians in Geneva, Switzerland. The study was extended to the analysis of mortality and incidence of cancer among both groups. The cohorts included 1916 painters and 1948 electricians who were resident in the Canton of Geneva at the 1970 census. The painters were followed up for 14 years and a review of the causes of the 254 deaths and 121 disability pensions gave no case of presenile dementia. However, the higher incidence of disability among painters than among electricians may have resulted from the chronic effects of solvent exposure. Even so, in this study, solvent exposure was confounded with alcoholism which was associated with neuropsychiatric disease in 12 of 20 painters and only one of ten electricians. The authors conclude that there was not sufficient evidence to support the existence of a solvent related painters' syndrome. A highly significant excess of lung cancer among painters was possibly related to occupational exposure to asbestos (1332214) and zinc-chromate (13530659). An increased risk of biliary tract cancer and bladder cancer was noted in the painters and five cases of testicular cancer were found when 1.6 would have been expected. Risk for cerebrovascular disease was supported by the disability study which showed eight cases among painters and none among electricians. No significant excess of cancer was found for any specific site among electricians. The numbers were too small to adequately assess possible links between working as an electrician and the incidence of leukemia or brain tumor."
1238229,Moller 1989,Intradermal Testing in Doubtful Cases of Contact Allergy to Metals,"A study of the ability of intradermal testing to detect doubtful cases of metal contact allergy was conducted. Altogether, 1670 patients were patch tested with a standard series of allergens at a Swedish dermatological clinic over a 3 year period. The patients were also interviewed to obtain information about possible histories of atopy and metal allergy. A total of 350 patients gave a positive response to one or more metal salts; 66 patients gave ambiguous or conflicting test results to chromium (7440473), cobalt (7440484), or nickel (7440020). Of these, 49 had test reactions that were difficult to read at 72 hours, ten gave negative reactions although they had a positive history of metal allergy, and seven had clinically diagnosed metal allergy but gave negative test results. These were evaluated further by injecting them intradermally with 0.029 percent potassium-dichromate (7778509), 0.013 percent cobalt-chloride (7646799), or 0.016 percent nickel-sulfate (7786814). In the patients with ambiguous patch test results, intradermal testing revealed seven positive reactions to chromium, five to cobalt, and 12 to nickel. Eleven of these were atopic and 13 had a history of metal allergy. In the group with positive metal allergy histories but negative patch test results, intradermal testing revealed two positive reactions to nickel and one to cobalt. In the group with clinically diagnosed contact allergy, four reacted positively to the intradermal tests. The author concludes that intradermal testing is easy to perform, lacks most of the technical disadvantages of the patch test, and is very useful for revealing false positive patch test reactions.","Intradermal Testing in Doubtful Cases of Contact Allergy to Metals Abs: A study of the ability of intradermal testing to detect doubtful cases of metal contact allergy was conducted. Altogether, 1670 patients were patch tested with a standard series of allergens at a Swedish dermatological clinic over a 3 year period. The patients were also interviewed to obtain information about possible histories of atopy and metal allergy. A total of 350 patients gave a positive response to one or more metal salts; 66 patients gave ambiguous or conflicting test results to chromium (7440473), cobalt (7440484), or nickel (7440020). Of these, 49 had test reactions that were difficult to read at 72 hours, ten gave negative reactions although they had a positive history of metal allergy, and seven had clinically diagnosed metal allergy but gave negative test results. These were evaluated further by injecting them intradermally with 0.029 percent potassium-dichromate (7778509), 0.013 percent cobalt-chloride (7646799), or 0.016 percent nickel-sulfate (7786814). In the patients with ambiguous patch test results, intradermal testing revealed seven positive reactions to chromium, five to cobalt, and 12 to nickel. Eleven of these were atopic and 13 had a history of metal allergy. In the group with positive metal allergy histories but negative patch test results, intradermal testing revealed two positive reactions to nickel and one to cobalt. In the group with clinically diagnosed contact allergy, four reacted positively to the intradermal tests. The author concludes that intradermal testing is easy to perform, lacks most of the technical disadvantages of the patch test, and is very useful for revealing false positive patch test reactions."
1238225,Lahiri et al. 1988,A Chemical Analysis of Dust in the Leather Industry with Reference to the Presence of Possible Oncogenic Agents,"An analysis was made of carcinogens in dust from the leather industry and of their effects in laboratory animals exposed dermally to dust extracts. Dust was collected from exhaust sites and sweepings in the leather industry and was extracted in acetone and ether. Carcinogenic or cocarcinogenic chemicals identified in leather dust extracts (LDEs) included arsenic-sulfide (1303340), sodium-arsenate (7778430), cadmium (7440439) compounds, potassium-dichromate (7778509), other chromium (7440473) compounds, carbon-tetrachloride (56235), chlorophenols, ethylene-oxide (75218), and nitrophenol (25154556). LDE or dimethylbenzanthracene (DMBA) as positive control were painted on the skin of mice and histologic changes were assessed. Mice painted for 12 weeks with DMBA and evaluated at 20 weeks showed epithelial hyperplasia, atypical epithelial hyperplasia, papilloma, and squamous cell carcinoma. Subepithelial inflammation was noted, with dense collagenization similar to oral submucous fibrosis in six of 30 mice. No changes in liver or lung were observed. Milder changes were noted in mice treated once with DMBA. LDE induced similar alterations. Lungs also showed hyperplastic and metaplastic changes. Livers of 22 of 30 mice had hepatic cell necrosis, and proliferative activity with focal nodule formation was observed in five. Carcinoma developed in 53.3 and 6.67 percent of mice painted for 12 weeks with DMBA or LDE, respectively. A single DMBA treatment produced no malignancies. LDE for 12 weeks after one dose of DMBA produced carcinoma in 30 percent of mice, indicating cocarcinogenic activity of LDE. Liver and lung changes were noted in these mice. The authors conclude that LDE has carcinogenic and cocarcinogenic effects, causes bronchial and liver changes, and contains identifiable carcinogens and cocarcinogens.","A Chemical Analysis of Dust in the Leather Industry with Reference to the Presence of Possible Oncogenic Agents Abs: An analysis was made of carcinogens in dust from the leather industry and of their effects in laboratory animals exposed dermally to dust extracts. Dust was collected from exhaust sites and sweepings in the leather industry and was extracted in acetone and ether. Carcinogenic or cocarcinogenic chemicals identified in leather dust extracts (LDEs) included arsenic-sulfide (1303340), sodium-arsenate (7778430), cadmium (7440439) compounds, potassium-dichromate (7778509), other chromium (7440473) compounds, carbon-tetrachloride (56235), chlorophenols, ethylene-oxide (75218), and nitrophenol (25154556). LDE or dimethylbenzanthracene (DMBA) as positive control were painted on the skin of mice and histologic changes were assessed. Mice painted for 12 weeks with DMBA and evaluated at 20 weeks showed epithelial hyperplasia, atypical epithelial hyperplasia, papilloma, and squamous cell carcinoma. Subepithelial inflammation was noted, with dense collagenization similar to oral submucous fibrosis in six of 30 mice. No changes in liver or lung were observed. Milder changes were noted in mice treated once with DMBA. LDE induced similar alterations. Lungs also showed hyperplastic and metaplastic changes. Livers of 22 of 30 mice had hepatic cell necrosis, and proliferative activity with focal nodule formation was observed in five. Carcinoma developed in 53.3 and 6.67 percent of mice painted for 12 weeks with DMBA or LDE, respectively. A single DMBA treatment produced no malignancies. LDE for 12 weeks after one dose of DMBA produced carcinoma in 30 percent of mice, indicating cocarcinogenic activity of LDE. Liver and lung changes were noted in these mice. The authors conclude that LDE has carcinogenic and cocarcinogenic effects, causes bronchial and liver changes, and contains identifiable carcinogens and cocarcinogens."
1238224,Levine and  Eisenbud 1988,Have We Overlooked Important Cohorts for Follow-up Studies?: Report of the Chemical Industry Institute of Toxicology Conference of World War II-Era Industrial Health Specialists,"Highlights of the discussions of 16 industrial hygienists and physicians who had been in practice during and prior to World War-II were reported. They had met to identify cohorts of workers then heavily exposed to toxic substances, but for whom followup studies had not been conducted. One example was the rotogravure workers who were exposed to benzene (71432); symptoms of bone marrow suppression and deaths from aplastic anemia were demonstrated among this group. Workers in the beryllium (7440417) extraction and fabrication industry are now being studied. Another group exposed to beryllium included those involved in the manufacture of fluorescent lamps. Halowax, a mixture of chlorinated biphenyls and naphthalenes, was used for insulating condensers, other electronic components used and for cables on naval ships. Hatters exposed to mercury (7439976) have never been followed up since the original discovery of neurologic effects. Exposures to drugs in the pharmaceutical industry should be investigated. The use of tetrachloroethane (630206) as a solvent in gas proofing uniforms caused jaundice and some deaths. Trichloroethylene (79016) has been used as an industrial solvent for years, but the potential for toxicity in humans has not been fully determined. The viscose rayon industry produced cases of carbon-disulfide (75150) psychosis and paresis. Exposure to zinc-chromate (13530659) occurred in the spray painting of aircraft for camouflage. Additional studies may be needed for individuals employed in ore refining, chemical manufacturing, dye manufacturing, baking, mining, manufacturing of thermometers and barometers, propellant manufacturing, weapons manufacturing, case iron pipe manufacturing, gold purification, and manufacture and shell loading. The authors recommend that studies on these populations should be initiated while knowledgeable persons and necessary records can still be found.","Have We Overlooked Important Cohorts for Follow-up Studies?: Report of the Chemical Industry Institute of Toxicology Conference of World War II-Era Industrial Health Specialists Abs: Highlights of the discussions of 16 industrial hygienists and physicians who had been in practice during and prior to World War-II were reported. They had met to identify cohorts of workers then heavily exposed to toxic substances, but for whom followup studies had not been conducted. One example was the rotogravure workers who were exposed to benzene (71432); symptoms of bone marrow suppression and deaths from aplastic anemia were demonstrated among this group. Workers in the beryllium (7440417) extraction and fabrication industry are now being studied. Another group exposed to beryllium included those involved in the manufacture of fluorescent lamps. Halowax, a mixture of chlorinated biphenyls and naphthalenes, was used for insulating condensers, other electronic components used and for cables on naval ships. Hatters exposed to mercury (7439976) have never been followed up since the original discovery of neurologic effects. Exposures to drugs in the pharmaceutical industry should be investigated. The use of tetrachloroethane (630206) as a solvent in gas proofing uniforms caused jaundice and some deaths. Trichloroethylene (79016) has been used as an industrial solvent for years, but the potential for toxicity in humans has not been fully determined. The viscose rayon industry produced cases of carbon-disulfide (75150) psychosis and paresis. Exposure to zinc-chromate (13530659) occurred in the spray painting of aircraft for camouflage. Additional studies may be needed for individuals employed in ore refining, chemical manufacturing, dye manufacturing, baking, mining, manufacturing of thermometers and barometers, propellant manufacturing, weapons manufacturing, case iron pipe manufacturing, gold purification, and manufacture and shell loading. The authors recommend that studies on these populations should be initiated while knowledgeable persons and necessary records can still be found."
1238223,Endo and  Watanabe 1988,Analysis of Protective Activity of N-Acetylcysteine against Teratogenicity of Heavy Metals,"The possibility that some teratogenic and embryotoxic effects of heavy metals can be ameliorated by N-acetylcysteine (NAC) was investigated in mice. Female Jcl:ICR-mice were fed a regular diet containing 2.0 milligrams (mg) NAC or a control diet. Mice were fed the diets for a minimum of 4 weeks before gestation and throughout gestation. Within each dietary group the dams were further subdivided into treatment groups receiving a single dose of 8.0mg/kg methylmercury-chloride (115093), 15.0mg/kg chromium-trioxide (1333820), or 2.0mg/kg cadmium-chloride (10108642). These dose levels were selected to produce a moderate teratogenic effect, as previously reported in the literature. Syndactyly and cleft palate were the predominant anomalies in the chromium (7440473) and cadmium (7440439) treated groups whereas in the mercury (7439976) treated groups only cleft palate was observed. The rate of congenital malformations produced by these metals was two to three times higher in the fetuses of mice that were fed NAC in their diets than in those not fed NAC.","Analysis of Protective Activity of N-Acetylcysteine against Teratogenicity of Heavy Metals Abs: The possibility that some teratogenic and embryotoxic effects of heavy metals can be ameliorated by N-acetylcysteine (NAC) was investigated in mice. Female Jcl:ICR-mice were fed a regular diet containing 2.0 milligrams (mg) NAC or a control diet. Mice were fed the diets for a minimum of 4 weeks before gestation and throughout gestation. Within each dietary group the dams were further subdivided into treatment groups receiving a single dose of 8.0mg/kg methylmercury-chloride (115093), 15.0mg/kg chromium-trioxide (1333820), or 2.0mg/kg cadmium-chloride (10108642). These dose levels were selected to produce a moderate teratogenic effect, as previously reported in the literature. Syndactyly and cleft palate were the predominant anomalies in the chromium (7440473) and cadmium (7440439) treated groups whereas in the mercury (7439976) treated groups only cleft palate was observed. The rate of congenital malformations produced by these metals was two to three times higher in the fetuses of mice that were fed NAC in their diets than in those not fed NAC."
1238217,Ruhnek-Forsbeck et al. 1988,Comparative Multi-center Study with TRUE Test and Finn Chamber Patch Test Methods in Eight Swedish Hospitals,"A study was conducted to determine clinically the accuracy of the allergen dosage proposed in TRUE Test (TT), a ready to use multiple patch test. TT was manufactured by incorporating allergens in different cellulose gels. Twelve different allergens and allergen mixtures were included in the first test panel. The subjects to be tested included 248 patients with past or present contact dermatitis, 19 with other skin diseases and 25 healthy volunteers. Comparisons were made with findings using the Finn Chamber technique (FC). Evaluations were made at 72 hours in 275 patients and 96 hours in 14 patients. In 98 individuals 156 allergens gave + to +++ reactions to one or both test methods. In 121 reaction pairs both tests gave positive results. In 16 reaction pairs positive results were obtained only to TT and in 19 pairs, only to FC. More frequent irritant reactions were obtained to potassium-dichromate (7778509) using the FC test whereas more irritant reactions for cobalt-chloride (7646799) were obtained with TT. The authors conclude there is good correlation between the two test methods which was particularly valuable in the strongly positive test reactions. They caution that most weak positive reactions should be suspected of being false positives","Comparative Multi-center Study with TRUE Test and Finn Chamber Patch Test Methods in Eight Swedish Hospitals Abs: A study was conducted to determine clinically the accuracy of the allergen dosage proposed in TRUE Test (TT), a ready to use multiple patch test. TT was manufactured by incorporating allergens in different cellulose gels. Twelve different allergens and allergen mixtures were included in the first test panel. The subjects to be tested included 248 patients with past or present contact dermatitis, 19 with other skin diseases and 25 healthy volunteers. Comparisons were made with findings using the Finn Chamber technique (FC). Evaluations were made at 72 hours in 275 patients and 96 hours in 14 patients. In 98 individuals 156 allergens gave + to +++ reactions to one or both test methods. In 121 reaction pairs both tests gave positive results. In 16 reaction pairs positive results were obtained only to TT and in 19 pairs, only to FC. More frequent irritant reactions were obtained to potassium-dichromate (7778509) using the FC test whereas more irritant reactions for cobalt-chloride (7646799) were obtained with TT. The authors conclude there is good correlation between the two test methods which was particularly valuable in the strongly positive test reactions. They caution that most weak positive reactions should be suspected of being false positives"
1238207,Hayes 1988,Review of occupational epidemiology of chromium chemicals and respiratory cancer,"Several epidemiologic studies have investigated the association between cancer risk and employment in chromium producing and using industries. Strong and consistent associations have been found between employment in the primary chemical producing industry and the risk for respiratory cancer. Workers employed in chromate pigment production and possibly spray painters of chromate pigment paints appear to be at excess risk of respiratory cancer. Chrome platers may also be at excess risk, although the evidence is limited. A few studies indicate that chromium alloy welding may also be an exposure source of concern. Some studies of ferrochromium alloy workers have shown an excess risk for respiratory cancer, although the risk may in part be due to concomitant exposures. The evidence indicates that the hexavalent form of chromium is the primary agent of chromium carcinogenesis. Solubility and other characteristics of chromium compounds may also play a role in determining risk.","Review of occupational epidemiology of chromium chemicals and respiratory cancer Abs: Several epidemiologic studies have investigated the association between cancer risk and employment in chromium producing and using industries. Strong and consistent associations have been found between employment in the primary chemical producing industry and the risk for respiratory cancer. Workers employed in chromate pigment production and possibly spray painters of chromate pigment paints appear to be at excess risk of respiratory cancer. Chrome platers may also be at excess risk, although the evidence is limited. A few studies indicate that chromium alloy welding may also be an exposure source of concern. Some studies of ferrochromium alloy workers have shown an excess risk for respiratory cancer, although the risk may in part be due to concomitant exposures. The evidence indicates that the hexavalent form of chromium is the primary agent of chromium carcinogenesis. Solubility and other characteristics of chromium compounds may also play a role in determining risk."
1238198,Arber et al. 1988,Determination of Chromium Oxidation State by X-Ray Fluorescence Spectrometry: Application to Chromium(VI) and Chromium(III) Determination in Occupational Hygiene Samples,"An attempt was made to extend the application of x-ray fluorescence analysis by studying whether chemical effects in the spectra can also be used to determine the chromium(VI) (18540299) content. Toward this end the chromium (7440473) K-spectra x-ray emission lines of various chromium salts and welding fumes were studied and changes in peak, position, and profile observed. Changes were related to oxidation state and ligand environment. While all the chromium K-spectra showed changes in peak position and/or peak profile, their analytical potential for determining the oxidation state of chromium varied considerably. The intensity ratio of Kbeta' to Kbeta1,3 was chosen as the best parameter for determining chromium valency. A series of studies was undertaken including the analysis of mixtures of finely ground chromic-oxide (1308389) (Cr2O3) and potassium-dichromate (7778509) (K2Cr2O7); mixtures of finely ground Cr2O3, K2Cr2O7, and iron-oxide (1317619); authentic welding fume samples; and layers of Cr2O3 and K2Cr2O7 deposited on mixed cellulose ester filters. A good correlation between the intensity ratio used and the proportion of chromium(VI) in the standards was obtained. Analysis of welding fume samples was more problematic due to high background values associated with manganese content. Significantly large errors were associated with the x-ray fluorescence method. It was difficult to measure the accuracy of this method when so few samples were analyzed. The authors conclude that even if the error in determining the chromium(VI) to total chromium ratio is on the order of plus or minus 15 percent, the method is fast and cost effective and may still be useful in occupational hygiene to provide an indication of chromium(VI) levels and for the preliminary sorting of samples.","Determination of Chromium Oxidation State by X-Ray Fluorescence Spectrometry: Application to Chromium(VI) and Chromium(III) Determination in Occupational Hygiene Samples Abs: An attempt was made to extend the application of x-ray fluorescence analysis by studying whether chemical effects in the spectra can also be used to determine the chromium(VI) (18540299) content. Toward this end the chromium (7440473) K-spectra x-ray emission lines of various chromium salts and welding fumes were studied and changes in peak, position, and profile observed. Changes were related to oxidation state and ligand environment. While all the chromium K-spectra showed changes in peak position and/or peak profile, their analytical potential for determining the oxidation state of chromium varied considerably. The intensity ratio of Kbeta' to Kbeta1,3 was chosen as the best parameter for determining chromium valency. A series of studies was undertaken including the analysis of mixtures of finely ground chromic-oxide (1308389) (Cr2O3) and potassium-dichromate (7778509) (K2Cr2O7); mixtures of finely ground Cr2O3, K2Cr2O7, and iron-oxide (1317619); authentic welding fume samples; and layers of Cr2O3 and K2Cr2O7 deposited on mixed cellulose ester filters. A good correlation between the intensity ratio used and the proportion of chromium(VI) in the standards was obtained. Analysis of welding fume samples was more problematic due to high background values associated with manganese content. Significantly large errors were associated with the x-ray fluorescence method. It was difficult to measure the accuracy of this method when so few samples were analyzed. The authors conclude that even if the error in determining the chromium(VI) to total chromium ratio is on the order of plus or minus 15 percent, the method is fast and cost effective and may still be useful in occupational hygiene to provide an indication of chromium(VI) levels and for the preliminary sorting of samples."
1238196,Dubes and  Mack 1988,Asbestos-Mediated Transfection of Mammalian Cell Cultures,"The ability of asbestos (1332214) to mediate transfection was studied in-vitro. Thirteen asbestos samples including amosite (12172735), anthophyllite (17068789), chrysotile (12001295), and crocidolite (12001284) were incubated with cell lines including epithelial cells from chimpanzee liver (CLI), epithelial cells from normal rhesus-monkey kidneys, KB-human carcinoma cells, and NIH-3T3-mouse embryo fibroblasts that were inoculated with RNA from poliovirus-1, poliovirus-2, echovirus-7, or encephalomyocarditis virus. Asbestos concentrations ranged up to 10 milligrams per milliliter. The asbestos samples were premixed with the RNA or added before or after the RNA. Some cultures contained double stranded DNA from salmon sperm. The extent of transfection was determined by assaying the cultures for plaque formation. All asbestos samples mediated transfection. The extent of transfection was proportional to asbestos concentrations. Asbestos premixed with viral RNA induced a greater degree of transfection than when it was added before or after the RNA. Salmon sperm DNA added to the cultures decreased the extent of transfection when used as part of the inoculum but not when added before or after RNA inoculation. Additionally, CLI cells were treated with chrysotile or crocidolite which were compared with the ability of bentonite (1302789), calcium-phosphate (7758874), chromic-oxide (1308389), ferric-oxide (1309371), kaolin (1332587), and talc (14807966) to mediate transfection after inoculation with poliovirus-1 RNA. The ability of asbestos to promote transfection was less than that of talc, kaolin, and chromic-oxide, but greater than that of bentonite, calcium-phosphate, and ferric-oxide. The authors conclude that asbestos mediates transfection of mammalian cells with viral RNA. The ability to mediate transfection may be one of several factors involved in asbestos carcinogenesis.","Asbestos-Mediated Transfection of Mammalian Cell Cultures Abs: The ability of asbestos (1332214) to mediate transfection was studied in-vitro. Thirteen asbestos samples including amosite (12172735), anthophyllite (17068789), chrysotile (12001295), and crocidolite (12001284) were incubated with cell lines including epithelial cells from chimpanzee liver (CLI), epithelial cells from normal rhesus-monkey kidneys, KB-human carcinoma cells, and NIH-3T3-mouse embryo fibroblasts that were inoculated with RNA from poliovirus-1, poliovirus-2, echovirus-7, or encephalomyocarditis virus. Asbestos concentrations ranged up to 10 milligrams per milliliter. The asbestos samples were premixed with the RNA or added before or after the RNA. Some cultures contained double stranded DNA from salmon sperm. The extent of transfection was determined by assaying the cultures for plaque formation. All asbestos samples mediated transfection. The extent of transfection was proportional to asbestos concentrations. Asbestos premixed with viral RNA induced a greater degree of transfection than when it was added before or after the RNA. Salmon sperm DNA added to the cultures decreased the extent of transfection when used as part of the inoculum but not when added before or after RNA inoculation. Additionally, CLI cells were treated with chrysotile or crocidolite which were compared with the ability of bentonite (1302789), calcium-phosphate (7758874), chromic-oxide (1308389), ferric-oxide (1309371), kaolin (1332587), and talc (14807966) to mediate transfection after inoculation with poliovirus-1 RNA. The ability of asbestos to promote transfection was less than that of talc, kaolin, and chromic-oxide, but greater than that of bentonite, calcium-phosphate, and ferric-oxide. The authors conclude that asbestos mediates transfection of mammalian cells with viral RNA. The ability to mediate transfection may be one of several factors involved in asbestos carcinogenesis."
1238191,Illuminati et al. 1988,Occupational Airborne Contact Dermatitis in a Florist,"A case history of occupational airborne contact dermatitis due to plant exposure was reported in a florist. The subject was a 35 year old female who presented with suspected contact dermatitis of the face and hands; the patient had been a florist for 2 years with symptoms of 1 year duration. Symptoms included redness, scaling, and fissuring of the back and palm of the right hand and palm of the left hand, red and scaly facial skin, and swollen eyelids. Positive patch test reactions were obtained to nickel-sulfate, cobalt-chloride, potassium-dichromate, thiomersal, and leaf and flower extracts from the plants Alstroemeria, Chrysanthemum-x-hortorum, and Tulipa. No reactions were obtained to a pesticide series. Clinical manifestations were related to the plant allergens such as sesquiterpene lactones and tuliposide-A (19870305), and not to fungicides. Airborne contact was suggested because of the involvement of the upper eyelids and skin around the lips. Clinical symptoms disappeared upon removal of all offending families of plants from the subject's shop.","Occupational Airborne Contact Dermatitis in a Florist Abs: A case history of occupational airborne contact dermatitis due to plant exposure was reported in a florist. The subject was a 35 year old female who presented with suspected contact dermatitis of the face and hands; the patient had been a florist for 2 years with symptoms of 1 year duration. Symptoms included redness, scaling, and fissuring of the back and palm of the right hand and palm of the left hand, red and scaly facial skin, and swollen eyelids. Positive patch test reactions were obtained to nickel-sulfate, cobalt-chloride, potassium-dichromate, thiomersal, and leaf and flower extracts from the plants Alstroemeria, Chrysanthemum-x-hortorum, and Tulipa. No reactions were obtained to a pesticide series. Clinical manifestations were related to the plant allergens such as sesquiterpene lactones and tuliposide-A (19870305), and not to fungicides. Airborne contact was suggested because of the involvement of the upper eyelids and skin around the lips. Clinical symptoms disappeared upon removal of all offending families of plants from the subject's shop."
1238190,Hooftman et al. 1988,Cytotoxicity of some types of welding fume particles to bovine alveolar macrophages,"The subject of this study is the in vitro cytotoxicity to bovine alveolar macrophages of particles produced by various metal welding processes, such as manual metal arc welding (MMA) and metal inert gas welding (MIG) of both stainless steel (SS) and mild steel (MS), and MMA welding of cast iron (CI). Macrophages were exposed to particles suspended in tissue culture medium. Viability after 18 h of exposure was determined by trypan blue exclusion. Phagocytic activity was determined from the uptake of latex microspheres by exposed macrophages. The contribution of soluble chromium to the effects of the fume particles was estimated by testing potassium chromate. Welding of stainless steel generates the most toxic fumes, and MMA-SS particles are far more toxic than MIG-SS particles. MIG-SS particles behaved more or less like other inert particles. The observed cytotoxic effects are largely due to the soluble chromium content of the fume particles, particularly those from MMA-SS welding. The other types of particle may contain different toxic substances: insoluble compounds and synergism of elements may play a part. Since the fibrogenic power of particles is known to be related to their cytotoxicity to alveolar macrophages, particles from MMA-SS welding should be regarded as being potentially fibrogenic. In addition, they may seriously impair the phagocytic function of macrophages. thereby rendering the lungs more vulnerable to microbial infection.","Cytotoxicity of some types of welding fume particles to bovine alveolar macrophages Abs: The subject of this study is the in vitro cytotoxicity to bovine alveolar macrophages of particles produced by various metal welding processes, such as manual metal arc welding (MMA) and metal inert gas welding (MIG) of both stainless steel (SS) and mild steel (MS), and MMA welding of cast iron (CI). Macrophages were exposed to particles suspended in tissue culture medium. Viability after 18 h of exposure was determined by trypan blue exclusion. Phagocytic activity was determined from the uptake of latex microspheres by exposed macrophages. The contribution of soluble chromium to the effects of the fume particles was estimated by testing potassium chromate. Welding of stainless steel generates the most toxic fumes, and MMA-SS particles are far more toxic than MIG-SS particles. MIG-SS particles behaved more or less like other inert particles. The observed cytotoxic effects are largely due to the soluble chromium content of the fume particles, particularly those from MMA-SS welding. The other types of particle may contain different toxic substances: insoluble compounds and synergism of elements may play a part. Since the fibrogenic power of particles is known to be related to their cytotoxicity to alveolar macrophages, particles from MMA-SS welding should be regarded as being potentially fibrogenic. In addition, they may seriously impair the phagocytic function of macrophages. thereby rendering the lungs more vulnerable to microbial infection."
1238189,Romaguera et al. 1988,Epidemic of Occupational Contact Dermatitis from Ranitidine,"An outbreak of occupational contact dermatitis from ranitidine (66357355) was described. Sixteen workers in a chemical factory that manufactured ranitidine-base developed contact dermatitis. The patients consisted of 11 office workers (ten males), two male chemists, two male maintenance workers, and one female secretary. The dermatitis was characterized by eczema on the backs of the hands, dyshidrosis on the fingers, eczematous plaques on the tops of the feet and the forearms, and erythematous edematous papules on the face and neck. One patient had a dry scaly fissured eczema of the scrotum. The facial lesions resembled those of seborrheic dermatitis. Itching varied from individual to individual. Some patients reported dizziness, vomiting, rhinitis, bronchitis, and conjunctivitis. Eleven patients and 25 comparisons were patch tested with a standard allergen series, ranitidine-base, and ranitidine-chlorhydrate. All 11 patients were positive to both ranitidine-base and ranitidine-chlorhydrate. In the standard series, one patient reacted to metallic mercury and colophony, one to potassium-dichromate, cobalt-chloride, and cobalt-sulfate, one to potassium-dichromate, and one to thiuram mix and mercapto mix. The secretary's dermatitis was cleared with an unspecified treatment. The symptoms in the other patients cleared when they went on sick leave but recurred when they returned to work. Patients with seborrheic dermatitis like facial lesions required at least 3 months before their condition cleared. The cause of the sudden outbreak could not be determined.","Epidemic of Occupational Contact Dermatitis from Ranitidine Abs: An outbreak of occupational contact dermatitis from ranitidine (66357355) was described. Sixteen workers in a chemical factory that manufactured ranitidine-base developed contact dermatitis. The patients consisted of 11 office workers (ten males), two male chemists, two male maintenance workers, and one female secretary. The dermatitis was characterized by eczema on the backs of the hands, dyshidrosis on the fingers, eczematous plaques on the tops of the feet and the forearms, and erythematous edematous papules on the face and neck. One patient had a dry scaly fissured eczema of the scrotum. The facial lesions resembled those of seborrheic dermatitis. Itching varied from individual to individual. Some patients reported dizziness, vomiting, rhinitis, bronchitis, and conjunctivitis. Eleven patients and 25 comparisons were patch tested with a standard allergen series, ranitidine-base, and ranitidine-chlorhydrate. All 11 patients were positive to both ranitidine-base and ranitidine-chlorhydrate. In the standard series, one patient reacted to metallic mercury and colophony, one to potassium-dichromate, cobalt-chloride, and cobalt-sulfate, one to potassium-dichromate, and one to thiuram mix and mercapto mix. The secretary's dermatitis was cleared with an unspecified treatment. The symptoms in the other patients cleared when they went on sick leave but recurred when they returned to work. Patients with seborrheic dermatitis like facial lesions required at least 3 months before their condition cleared. The cause of the sudden outbreak could not be determined."
1238187,Dinis et al. 1988,Occupational Contact Dermatitis from Vitamin K3 Sodium Bisulphite,"A case history of occupational dermatitis resulting from exposure to the sodium-bisulfite salt of vitamin-K3 (58275) was reported. A 40 year old man developed acute dermatitis in exposed body areas (face, neck, hands, forearms) about 1 month after starting a job preparing pig feeds. Preparation involved the addition of mixes containing mineral salts and vitamins to the feeds. Clinical testing was done 3 months later; positive patch tests were obtained to two of the mixtures the subject handled during work and to potassium-dichromate, to which he had been formerly exposed from cement. Upon testing of the specific mixture ingredients, the subject was found to test positive to the sodium-bisulfite salt of vitamin-K3; positive results were also obtained with Synkavit (containing vitamin-K4), indicating a cross reaction. The authors conclude that contact dermatitis in this case is due primarily to airborne vitamin-K3 exposure; the rapid sensitization and the very acute clinical picture are surprising based on the degree of contact.","Occupational Contact Dermatitis from Vitamin K3 Sodium Bisulphite Abs: A case history of occupational dermatitis resulting from exposure to the sodium-bisulfite salt of vitamin-K3 (58275) was reported. A 40 year old man developed acute dermatitis in exposed body areas (face, neck, hands, forearms) about 1 month after starting a job preparing pig feeds. Preparation involved the addition of mixes containing mineral salts and vitamins to the feeds. Clinical testing was done 3 months later; positive patch tests were obtained to two of the mixtures the subject handled during work and to potassium-dichromate, to which he had been formerly exposed from cement. Upon testing of the specific mixture ingredients, the subject was found to test positive to the sodium-bisulfite salt of vitamin-K3; positive results were also obtained with Synkavit (containing vitamin-K4), indicating a cross reaction. The authors conclude that contact dermatitis in this case is due primarily to airborne vitamin-K3 exposure; the rapid sensitization and the very acute clinical picture are surprising based on the degree of contact."
1238182,Arillo et al. 1987,Reduction of Hexavalent Chromium by Mitochondria: Methodological Implications and Possible Mechanisms,"The reduction of hexavalent chromium (18540299) (Cr(VI)) by rat mitochondria was investigated, in order to evaluate the effects of various methods for determining Cr(VI) as well as the mechanism of its reduction. Liver mitochondria isolated from male Wistar-rats were incubated with potassium-dichromate (7778509) in the presence or absence of glutathione, NADH or NADPH. The Cr(VI) concentration in the mixtures after incubation was determined by a colorimetric method based on diphenylcarbazide (DPC) reagent using aqueous samples, the colorimetric method carried out on amberlite-LA2 extracts, or atomic absorption spectrophotometry performed on LA2 extracts. Dose dependent decreases in the recovery of Cr(VI) occurred with the DPC colorimetric method in the presence of greater than 0.1 millimolar (mM) NADH or NADPH, when compared to incubation systems not containing NADH or NADPH. The presence of glutathione had no effect on Cr(VI) recovery. When the other two procedures were used Cr(VI) recovery was always close to 100 percent, except at NADPH concentrations of 1mM when 93 percent recovery was obtained. Mitochondria were also incubated with potassium-dichromate using succinate or glutamate as substrates in the presence or absence of rotenone, adenosine-diphosphate (ADP), cyanide, antimycin or carbonyl-cyanide-m-chlorophenylhydrazone (CLCCP). With glutamate as substrate Cr(VI) reduction was promoted by rotenone and cyanide but blocked by ADP and CLCCP. The opposite results were obtained with succinate as substrate. The authors conclude that rat liver mitochondria can reduce Cr(VI) by three mechanisms: a pathway independent of endogenous sulfhydryl groups, a mechanism mediated by mitochondrial DT-diaphorase or a mechanism mediated by mitochondrial proton ejection. They note that NADH and NADPH interfere with colorimetric methods for determining Cr(VI) unless the samples are first extracted on LA2.","Reduction of Hexavalent Chromium by Mitochondria: Methodological Implications and Possible Mechanisms Abs: The reduction of hexavalent chromium (18540299) (Cr(VI)) by rat mitochondria was investigated, in order to evaluate the effects of various methods for determining Cr(VI) as well as the mechanism of its reduction. Liver mitochondria isolated from male Wistar-rats were incubated with potassium-dichromate (7778509) in the presence or absence of glutathione, NADH or NADPH. The Cr(VI) concentration in the mixtures after incubation was determined by a colorimetric method based on diphenylcarbazide (DPC) reagent using aqueous samples, the colorimetric method carried out on amberlite-LA2 extracts, or atomic absorption spectrophotometry performed on LA2 extracts. Dose dependent decreases in the recovery of Cr(VI) occurred with the DPC colorimetric method in the presence of greater than 0.1 millimolar (mM) NADH or NADPH, when compared to incubation systems not containing NADH or NADPH. The presence of glutathione had no effect on Cr(VI) recovery. When the other two procedures were used Cr(VI) recovery was always close to 100 percent, except at NADPH concentrations of 1mM when 93 percent recovery was obtained. Mitochondria were also incubated with potassium-dichromate using succinate or glutamate as substrates in the presence or absence of rotenone, adenosine-diphosphate (ADP), cyanide, antimycin or carbonyl-cyanide-m-chlorophenylhydrazone (CLCCP). With glutamate as substrate Cr(VI) reduction was promoted by rotenone and cyanide but blocked by ADP and CLCCP. The opposite results were obtained with succinate as substrate. The authors conclude that rat liver mitochondria can reduce Cr(VI) by three mechanisms: a pathway independent of endogenous sulfhydryl groups, a mechanism mediated by mitochondrial DT-diaphorase or a mechanism mediated by mitochondrial proton ejection. They note that NADH and NADPH interfere with colorimetric methods for determining Cr(VI) unless the samples are first extracted on LA2."
1238179,Ottenwälder et al. 1987,Membrane permeability and intracellular disposition of 51Cr(VI) in human red blood cells,"Fast uptake kinetics of 51Cr(VI) into red blood cells (RBC) were studied. The uptake was determined as a process composed of two different first order processes with half lives of 23 sec and 10.4 min. Whereas the uptake of Cr(VI) in resuspended RBC (0.9% saline) was almost complete, in blood a portion of approximately 15% of the applied dose remained in plasma and did not penetrate into RBC, even after longer time periods. Over the concentration range studied (10 ?M?50mM), the fast initial uptake followed Michaelis?Menten?kinetics. The maximum capacity of this Cr(VI) transport into RBC of man was 3.1 × 108 ions × cell?1 × min?1. It is likely that Cr(VI) is transported under participation of “band?3?protein”;, a physiological anion carrier system of the RBC membrane. Intracellularly, chromium is almost quantitatively bound to hemoglobin, and thereby trapped for the cell's lifetime.","Membrane permeability and intracellular disposition of 51Cr(VI) in human red blood cells Abs: Fast uptake kinetics of 51Cr(VI) into red blood cells (RBC) were studied. The uptake was determined as a process composed of two different first order processes with half lives of 23 sec and 10.4 min. Whereas the uptake of Cr(VI) in resuspended RBC (0.9% saline) was almost complete, in blood a portion of approximately 15% of the applied dose remained in plasma and did not penetrate into RBC, even after longer time periods. Over the concentration range studied (10 ?M?50mM), the fast initial uptake followed Michaelis?Menten?kinetics. The maximum capacity of this Cr(VI) transport into RBC of man was 3.1 × 108 ions × cell?1 × min?1. It is likely that Cr(VI) is transported under participation of “band?3?protein”;, a physiological anion carrier system of the RBC membrane. Intracellularly, chromium is almost quantitatively bound to hemoglobin, and thereby trapped for the cell's lifetime."
1238178,Venier et al. 1987,Interactions of Chromium with Nitrilotriacetic Acid (NTA) in the Induction of Genetic Effects in Bacteria,"A study was made of the genotoxic activity of nitrilotriacetic-acid (139139) (NTA) and its interactions with soluble and insoluble hexavalent chromium (7440473) (Cr) compounds in inducing gene mutations and damage to DNA in bacteria. Point mutations in Salmonella-typhimurium (TA-100) were not induced by NTA alone nor were there any modifications of the direct mutagenicity of potassium-dichromate (7778509). The mutagenic activity of lead-chromate (7758976) was clearly evident in the Salmonella microsome assay only when NTA was present. There was a direct correlation between the amounts of Cr(VI) solubilized by NTA and the degree of mutagenicity observed. NTA did not demonstrate any mutagenic activity in a fluctuation test using Escherichia-coli. However, the presence of NTA significantly increased the mutagenicity of potassium-dichromate besides that of lead-chromate. When NTA was mixed with insoluble lead-chromate, the release of genotoxic Cr(VI) ions resulted. In the SOS chromotest, NTA was also negative. The authors conclude that NTA has the ability to elicit the genotoxicity of insoluble heavy metals in bacteria and can accentuate the genetic effects under the proper conditions. NTA itself may have a slight genotoxic potential for the induction of DNA damage.","Interactions of Chromium with Nitrilotriacetic Acid (NTA) in the Induction of Genetic Effects in Bacteria Abs: A study was made of the genotoxic activity of nitrilotriacetic-acid (139139) (NTA) and its interactions with soluble and insoluble hexavalent chromium (7440473) (Cr) compounds in inducing gene mutations and damage to DNA in bacteria. Point mutations in Salmonella-typhimurium (TA-100) were not induced by NTA alone nor were there any modifications of the direct mutagenicity of potassium-dichromate (7778509). The mutagenic activity of lead-chromate (7758976) was clearly evident in the Salmonella microsome assay only when NTA was present. There was a direct correlation between the amounts of Cr(VI) solubilized by NTA and the degree of mutagenicity observed. NTA did not demonstrate any mutagenic activity in a fluctuation test using Escherichia-coli. However, the presence of NTA significantly increased the mutagenicity of potassium-dichromate besides that of lead-chromate. When NTA was mixed with insoluble lead-chromate, the release of genotoxic Cr(VI) ions resulted. In the SOS chromotest, NTA was also negative. The authors conclude that NTA has the ability to elicit the genotoxicity of insoluble heavy metals in bacteria and can accentuate the genetic effects under the proper conditions. NTA itself may have a slight genotoxic potential for the induction of DNA damage."
1238176,Parashar et al. 1987,Spectrophotometric Determination of Sulphur Dioxide,"A method for the determination of sulfur-dioxide (7446095) (SO2) in air using the reduction of hexavalent chromium by SO2 trapped in aqueous morpholine was reported. SO2 gas generated by the reaction of hydrochloric-acid and sodium-sulfite was collected in a gas sampler and diluted with air to a concentration of 20 micrograms per milliliter. The SO2 gas was injected into a series of Corning gas samplers in volumes of 1, 2, 3, 4, and 5 milliliters. The samplers were flushed with nitrogen through a series of micro impingers containing 0.4 percent morpholine solution, and the amount of SO2 absorbed in the impingers was determined. The trapped SO2 was exposed to potassium-chromate, reducing the hexavalent chromium to trivalent chromium. Reaction of the remaining hexavalent compound with diphenylcarbazide yielded a soluble red violet complex with an absorption maximum at 540 nanometers. Water served as the control. The decrease in the absorbance values of the red violet complex were proportional to the amount of SO2 present in the samples for concentrations between 0.4 and 4.0 micrograms per milliliter. Nitrite ion was found to interfere with the method, and this could be prevented by adding a separate trap containing 0.6 percent sulfamic-acid prior to the micro impinger with the absorbing solution. Sulfide ion was also found to interfere, and the authors recommend checking the level of this contaminant when using this method. Application of the method to the analysis of SO2 in the air in a chemical laboratory was described.","Spectrophotometric Determination of Sulphur Dioxide Abs: A method for the determination of sulfur-dioxide (7446095) (SO2) in air using the reduction of hexavalent chromium by SO2 trapped in aqueous morpholine was reported. SO2 gas generated by the reaction of hydrochloric-acid and sodium-sulfite was collected in a gas sampler and diluted with air to a concentration of 20 micrograms per milliliter. The SO2 gas was injected into a series of Corning gas samplers in volumes of 1, 2, 3, 4, and 5 milliliters. The samplers were flushed with nitrogen through a series of micro impingers containing 0.4 percent morpholine solution, and the amount of SO2 absorbed in the impingers was determined. The trapped SO2 was exposed to potassium-chromate, reducing the hexavalent chromium to trivalent chromium. Reaction of the remaining hexavalent compound with diphenylcarbazide yielded a soluble red violet complex with an absorption maximum at 540 nanometers. Water served as the control. The decrease in the absorbance values of the red violet complex were proportional to the amount of SO2 present in the samples for concentrations between 0.4 and 4.0 micrograms per milliliter. Nitrite ion was found to interfere with the method, and this could be prevented by adding a separate trap containing 0.6 percent sulfamic-acid prior to the micro impinger with the absorbing solution. Sulfide ion was also found to interfere, and the authors recommend checking the level of this contaminant when using this method. Application of the method to the analysis of SO2 in the air in a chemical laboratory was described."
1238168,Hartwig and  Beyersmann 1987,Enhancement of UV and chromate mutagenesis by nickel ions in the Chinese hamster HGPRT assay,"The effect of nickel (7440020) ions on the mutagenic activity of potassium-dichromate (7778509) and ultraviolet (UV) radiation was studied in-vitro. Chinese-hamster V79 cells were exposed to 0 to 20 joules per square meter (J/m2) UV radiation, 0 to 2.000 millimolar (mM) nickel-chloride (7718549), or 0 to 0.200mM potassium-dichromate alone or in combination. Mutagenic activity was evaluated using the hypoxanthine-guanine-phosphoribosyl-transferase assay. Cytotoxicity was assessed by determining percent survival or cloning efficiency. All three agents showed significant cytotoxicity and mutagenic activity when administered alone. The spontaneous (control) mutation frequency was 2.4 mutants per million cells. Maximum increases in mutation frequency over the control value for the agents alone were 60.8 for UV at 10J/m2, 14.6 for 2mM nickel-chloride, and 6.3 for 0.200mM potassium-dichromate. UV radiation at 5J/m2 + 0.500mM nickel-chloride increased the mutation rate 11.2 times over the sum of the individual rates. The mutation rate after treatment with 0.100mM potassium-dichromate + 0.500mM nickel-chloride was 2.8 times that of the sum of the individual rates. The authors conclude that the enhancement of UV and potassium-dichromate mutagenicity by nickel-chloride is probably due to nickel ion interference with the repair of DNA lesions. Whether the comutagenic effect of nickel is reflected in a cocarcinogenic potential cannot be determined, and they recommend that this possibility be investigated.","Enhancement of UV and chromate mutagenesis by nickel ions in the Chinese hamster HGPRT assay Abs: The effect of nickel (7440020) ions on the mutagenic activity of potassium-dichromate (7778509) and ultraviolet (UV) radiation was studied in-vitro. Chinese-hamster V79 cells were exposed to 0 to 20 joules per square meter (J/m2) UV radiation, 0 to 2.000 millimolar (mM) nickel-chloride (7718549), or 0 to 0.200mM potassium-dichromate alone or in combination. Mutagenic activity was evaluated using the hypoxanthine-guanine-phosphoribosyl-transferase assay. Cytotoxicity was assessed by determining percent survival or cloning efficiency. All three agents showed significant cytotoxicity and mutagenic activity when administered alone. The spontaneous (control) mutation frequency was 2.4 mutants per million cells. Maximum increases in mutation frequency over the control value for the agents alone were 60.8 for UV at 10J/m2, 14.6 for 2mM nickel-chloride, and 6.3 for 0.200mM potassium-dichromate. UV radiation at 5J/m2 + 0.500mM nickel-chloride increased the mutation rate 11.2 times over the sum of the individual rates. The mutation rate after treatment with 0.100mM potassium-dichromate + 0.500mM nickel-chloride was 2.8 times that of the sum of the individual rates. The authors conclude that the enhancement of UV and potassium-dichromate mutagenicity by nickel-chloride is probably due to nickel ion interference with the repair of DNA lesions. Whether the comutagenic effect of nickel is reflected in a cocarcinogenic potential cannot be determined, and they recommend that this possibility be investigated."
1238167,Kortenkamp et al. 1987,Uptake of chromium (III) complexes by erythrocytes,"Trivalent chromium is assumed to be the ultimate genotoxic form of Cr after uptake and reduction of chromate in cells. Cr(III) also is an essential trace element for mammalia; it is required for the proper control of glucose metabolism. In both kinds of biological effects, Cr(III) is assumed to act in the form of complexes with biomolecules, but there is very little information about the uptake of such complexes through membranes. By electrothermal atomic absorption we investigated the time course of the binding and uptake with human erythrocytes of [Cr(glycine)3], [Cr(2,4?pentanedione)3], [Cr(glutathione)2]2?, [Cr(Cysteine)2]1?, [Cr(o?phenanthroline)2Cl2]1+ and [Cr(bipyridine)2Cl2]1+. In all cases chromium was bound and taken up significantly except with the cysteine complex which bound to the cells but sedimented with the cell envelope after cell lysis. The uptake of Cr(III) compounds was very slow. At 1 mM concentrations and 1 hour at 37°C the intracellular chromium was estimated to be between 0.5 to 2.0 x 10?18mol/cell. This corresponds to rate constants more than 3 orders of magnitude less than that of Cr(VI) uptake. We detected only a weak correlation of chromium uptake to the charge of the complexes or to the hydro?phobicity of the ligands.","Uptake of chromium (III) complexes by erythrocytes Abs: Trivalent chromium is assumed to be the ultimate genotoxic form of Cr after uptake and reduction of chromate in cells. Cr(III) also is an essential trace element for mammalia; it is required for the proper control of glucose metabolism. In both kinds of biological effects, Cr(III) is assumed to act in the form of complexes with biomolecules, but there is very little information about the uptake of such complexes through membranes. By electrothermal atomic absorption we investigated the time course of the binding and uptake with human erythrocytes of [Cr(glycine)3], [Cr(2,4?pentanedione)3], [Cr(glutathione)2]2?, [Cr(Cysteine)2]1?, [Cr(o?phenanthroline)2Cl2]1+ and [Cr(bipyridine)2Cl2]1+. In all cases chromium was bound and taken up significantly except with the cysteine complex which bound to the cells but sedimented with the cell envelope after cell lysis. The uptake of Cr(III) compounds was very slow. At 1 mM concentrations and 1 hour at 37°C the intracellular chromium was estimated to be between 0.5 to 2.0 x 10?18mol/cell. This corresponds to rate constants more than 3 orders of magnitude less than that of Cr(VI) uptake. We detected only a weak correlation of chromium uptake to the charge of the complexes or to the hydro?phobicity of the ligands."
1238165,Denniston and  Uyeki 1987,Distribution and HPLC study of chromium-51 binding sites in Chinese hamster ovary cells,"Chinese hamster ovary cells were cultured with chromium?51 chromate to study the site of chromium interaction with cell biomolecules. After incubation, cells were homogenized and separated into nuclear, mitochondrial, microsomal, and cytosolic fractions. Greater than 75% of the radioactivity was found in the cytosolic fraction. The supernatant from the centrifuged cell homogenate, which contained >90% of the chromium radioactivity, was subjected to chromatographic investigation. The combination of anion exchange and ion?pair high?performance liquid chromatography (HPLC) showed that at least three different molecular species interact with chromate or its reduced derivative, Cr(III). These species are glutathione, the nucleotides cytosine triphosphate, uridine triphosphate, guanine triphosphate, adenosine triphosphate, and adenosine diphosphate, plus an as yet unknown species of protein or peptide. Preliminary data for the specific activity of nucleoside triphosphates range from 6000 to 18,000 cpm/?g ribonucleoside triphosphate. The glutathione accounted for 50% of the observed radioactivity, the nucleotides for 30%, and the metalloprotein accounted for the remainder.","Distribution and HPLC study of chromium-51 binding sites in Chinese hamster ovary cells Abs: Chinese hamster ovary cells were cultured with chromium?51 chromate to study the site of chromium interaction with cell biomolecules. After incubation, cells were homogenized and separated into nuclear, mitochondrial, microsomal, and cytosolic fractions. Greater than 75% of the radioactivity was found in the cytosolic fraction. The supernatant from the centrifuged cell homogenate, which contained >90% of the chromium radioactivity, was subjected to chromatographic investigation. The combination of anion exchange and ion?pair high?performance liquid chromatography (HPLC) showed that at least three different molecular species interact with chromate or its reduced derivative, Cr(III). These species are glutathione, the nucleotides cytosine triphosphate, uridine triphosphate, guanine triphosphate, adenosine triphosphate, and adenosine diphosphate, plus an as yet unknown species of protein or peptide. Preliminary data for the specific activity of nucleoside triphosphates range from 6000 to 18,000 cpm/?g ribonucleoside triphosphate. The glutathione accounted for 50% of the observed radioactivity, the nucleotides for 30%, and the metalloprotein accounted for the remainder."
1238164,Bertolero et al. 1987,Quantitative Studies on Cytotoxicity and Neoplastic Transformation of BALB/3T3 Cells by Trace Metals,"The BALB/3T3-Cl-A31-1-1 cell line was tested to determine its potential use for the study of the effects of various metal salts in-vitro. Standard cytotoxicity and neoplastic transformation methods were used to determine quantitatively the cytotoxic effect of a variety of trace metals under identical test conditions. A broad sensitivity range for dose related cytotoxicity was found. Following incubation of BALB/3T3 cells with radiolabeled sodium-chromate (7775113), 70 percent of the chromium (7440473) (Cr) in the medium was extractable as anionic hexavalent Cr after 1 hour of incubation; at the end of 72 hours, the extractable amount was only 10 percent of the initial dose. In a cell free system, 72 hour incubation of Cr did not affect the chemical form of the metal, indicating that the BALB/3T3 cells played an active role in the chemical transformation of chromate. BALB/3T3 cells exposed to arsenic (7440382) (As), cadmium (7440439) (Cd), or Cr demonstrated positive dose related responses in neoplastic transformation assays. The relative effectiveness, expressed in terms of molar concentrations necessary to induce a predetermined level of biological response, was about the same for Cd and Cr, with lower activity for As. The authors conclude that the BALB/3T3 cell system is a valuable model for the study of correlations between cellular uptake, metabolism, cytotoxicity, and neoplastic transformation induced by metals in-vitro.","Quantitative Studies on Cytotoxicity and Neoplastic Transformation of BALB/3T3 Cells by Trace Metals Abs: The BALB/3T3-Cl-A31-1-1 cell line was tested to determine its potential use for the study of the effects of various metal salts in-vitro. Standard cytotoxicity and neoplastic transformation methods were used to determine quantitatively the cytotoxic effect of a variety of trace metals under identical test conditions. A broad sensitivity range for dose related cytotoxicity was found. Following incubation of BALB/3T3 cells with radiolabeled sodium-chromate (7775113), 70 percent of the chromium (7440473) (Cr) in the medium was extractable as anionic hexavalent Cr after 1 hour of incubation; at the end of 72 hours, the extractable amount was only 10 percent of the initial dose. In a cell free system, 72 hour incubation of Cr did not affect the chemical form of the metal, indicating that the BALB/3T3 cells played an active role in the chemical transformation of chromate. BALB/3T3 cells exposed to arsenic (7440382) (As), cadmium (7440439) (Cd), or Cr demonstrated positive dose related responses in neoplastic transformation assays. The relative effectiveness, expressed in terms of molar concentrations necessary to induce a predetermined level of biological response, was about the same for Cd and Cr, with lower activity for As. The authors conclude that the BALB/3T3 cell system is a valuable model for the study of correlations between cellular uptake, metabolism, cytotoxicity, and neoplastic transformation induced by metals in-vitro."
1238157,Farm 1986,Changing Patterns in Chromate Allergy,"An epidemiologic survey of chromate allergy was conducted. The purpose of the survey was to determine whether the incidence and pattern of contact sensitivity to chromate changed after iron-sulfate (7720787) had been added voluntarily to Swedish cement. A total of 531 patients at a dermatology clinic, 354 females, were patch tested with 0.5 percent potassium-dichromate (7778509). The results were evaluated according to International Contact Dermatitis Research Group criteria. The results were compared with those obtained in previous surveys, conducted in 1975 and 1980. The prevalence of positive responses in the current survey was 7.5 percent in males and 7.6 percent in females; the percentage of relevant responses (cases in which exposure to chromate containing products was proven) was 2.7 percent in males and 3.1 percent in females. The prevalence of positive responses in the 1980 survey was 3.7 percent in males and 5.4 percent in females. The corresponding prevalence of relevant responses was 0 and 3.3 percent. In the 1975 survey, 9.7 percent of the males and 3.7 percent of the females gave positive responses. The prevalence of relevant responses was 8.8 percent in males and 1.7 percent in females. The authors note that iron-sulfate was first added to Swedish cement between 1975 and 1980. The reason for the increase in relevant responses in females in recent years is not known, but could be due to increasing exposure to chromates in cement dust and detergents.","Changing Patterns in Chromate Allergy Abs: An epidemiologic survey of chromate allergy was conducted. The purpose of the survey was to determine whether the incidence and pattern of contact sensitivity to chromate changed after iron-sulfate (7720787) had been added voluntarily to Swedish cement. A total of 531 patients at a dermatology clinic, 354 females, were patch tested with 0.5 percent potassium-dichromate (7778509). The results were evaluated according to International Contact Dermatitis Research Group criteria. The results were compared with those obtained in previous surveys, conducted in 1975 and 1980. The prevalence of positive responses in the current survey was 7.5 percent in males and 7.6 percent in females; the percentage of relevant responses (cases in which exposure to chromate containing products was proven) was 2.7 percent in males and 3.1 percent in females. The prevalence of positive responses in the 1980 survey was 3.7 percent in males and 5.4 percent in females. The corresponding prevalence of relevant responses was 0 and 3.3 percent. In the 1975 survey, 9.7 percent of the males and 3.7 percent of the females gave positive responses. The prevalence of relevant responses was 8.8 percent in males and 1.7 percent in females. The authors note that iron-sulfate was first added to Swedish cement between 1975 and 1980. The reason for the increase in relevant responses in females in recent years is not known, but could be due to increasing exposure to chromates in cement dust and detergents."
1238154,Ryberg 1986,Problems with Methods for Measurement of Hexavalent Chromium Applied to Biological Samples,"A simple, rapid method was developed to eliminate problems caused by low pH during the analysis of cell homogenates for the presence of hexavalent chromium (18540299) (CrVI). Tests carried out with CrVI in the form of sodium-dichromate (7778509) revealed that at pH higher than 10, chromate was stable for hours even in the presence of reducing agents. Studies performed in biological materials, using the diphenylcarbazide method, resulted in the reduction of CrVI; removal of the reducing compound with aluminum-oxide and charcoal resulted in higher CrVI values in both microsomal suspensions and liver cells. It was demonstrated that the combination of charcoal and aluminum-oxide absorbed proteins and other absorbing materials such as nucleotides and certain metabolites from liver homogenates. Trivalent chromium (16065831) had a different absorption pattern from the same homogenates, depending on whether the source was chromium-chloride or potassium-dichromate. Following the application of treatment with charcoal and aluminum-oxide, the recovery of CrVI ranged from 98 to 100 percent. The use of liquid anion exchanger to perform selective extraction of CrVI from the water phase was not successful because of the presence of significant amounts of trivalent chromium in the form of anionic complexes.","Problems with Methods for Measurement of Hexavalent Chromium Applied to Biological Samples Abs: A simple, rapid method was developed to eliminate problems caused by low pH during the analysis of cell homogenates for the presence of hexavalent chromium (18540299) (CrVI). Tests carried out with CrVI in the form of sodium-dichromate (7778509) revealed that at pH higher than 10, chromate was stable for hours even in the presence of reducing agents. Studies performed in biological materials, using the diphenylcarbazide method, resulted in the reduction of CrVI; removal of the reducing compound with aluminum-oxide and charcoal resulted in higher CrVI values in both microsomal suspensions and liver cells. It was demonstrated that the combination of charcoal and aluminum-oxide absorbed proteins and other absorbing materials such as nucleotides and certain metabolites from liver homogenates. Trivalent chromium (16065831) had a different absorption pattern from the same homogenates, depending on whether the source was chromium-chloride or potassium-dichromate. Following the application of treatment with charcoal and aluminum-oxide, the recovery of CrVI ranged from 98 to 100 percent. The use of liquid anion exchanger to perform selective extraction of CrVI from the water phase was not successful because of the presence of significant amounts of trivalent chromium in the form of anionic complexes."
1238153,Alexander et al. 1986,Microsomal reduction of Cr VI,"The conditions, kinetics and cytochrome-P-450 involvement of hexavalent chromium (18540299) (CrVI) reduction in the form of sodium-chromate (7775113) were investigated in liver microsomes obtained from male Wistar-rats pretreated with Aroclor-1254 and phenobarbital. In the presence of oxygen, CrVI was reduced very slowly by the microsomes, this reducing activity being no different from that of boiled microsomes. In cytochrome-P-450 induced rats, the CrVI reducing activity of the microsomes increased. Carbon-monoxide produced incomplete inhibition of CrVI reduction. Kinetic studies in an anaerobic environment demonstrated velocity and affinity changes following pretreatment with cytochrome-P-450 inducers. Continuous exposure to 1 percent oxygen inhibited completely microsomal reduction of CrVI but the addition of chromate resulted in decreased oxygen consumption. Mitochondrial reduction of CrVI was not sensitive to oxygen. The authors conclude that the contribution of endoplasmic reticulum to the cellular reduction of CrVI in the presence of normal oxygenation is questionable, and they postulate that the binding of oxygen to the microsomal heme groups might inhibit the transfer of electrons to CrVI.","Microsomal reduction of Cr VI Abs: The conditions, kinetics and cytochrome-P-450 involvement of hexavalent chromium (18540299) (CrVI) reduction in the form of sodium-chromate (7775113) were investigated in liver microsomes obtained from male Wistar-rats pretreated with Aroclor-1254 and phenobarbital. In the presence of oxygen, CrVI was reduced very slowly by the microsomes, this reducing activity being no different from that of boiled microsomes. In cytochrome-P-450 induced rats, the CrVI reducing activity of the microsomes increased. Carbon-monoxide produced incomplete inhibition of CrVI reduction. Kinetic studies in an anaerobic environment demonstrated velocity and affinity changes following pretreatment with cytochrome-P-450 inducers. Continuous exposure to 1 percent oxygen inhibited completely microsomal reduction of CrVI but the addition of chromate resulted in decreased oxygen consumption. Mitochondrial reduction of CrVI was not sensitive to oxygen. The authors conclude that the contribution of endoplasmic reticulum to the cellular reduction of CrVI in the presence of normal oxygenation is questionable, and they postulate that the binding of oxygen to the microsomal heme groups might inhibit the transfer of electrons to CrVI."
1238152,Jenssen and  Syversen 1986,Cell cycle kinetics of K2Cr2O7 exposed asynchronous cells characterized by DNA distribution analysis and the Brd-Urd Hoechst 33258-technique,"The effects of potassium-dichromate (7778509) (PD) on the cell cycle were tested in exponentially growing rat glioma cells. The cells were exposed to PD for various periods of time, detached by trypsination, centrifuged and stained. Analysis of the DNA histograms demonstrated that the mitosis of cells which were in late S-phase or G2 plus M-phase of the cycle at the start of the treatment with 1.0 micromolar PD was similar to that of controls. Linear delay of mitosis was evident with increasing PD exposure time during the S-phase; maximum delay was equal to 5 hours for early S-phase cells. Treatment with PD, during Gl phase, induced a delay in the cell cycle similar to that following exposure during the entire S-phase of the cells. In a concentration of 5 micromolar, PD was toxic to the cells. PD had no effect on the mitotic pattern of cells in G2 plus M-phase of the cycle 4 hours after exposure to 1 or 5 micromolar PD; these cells underwent mitosis similar to controls. The authors conclude that the effect of Cr on cell parameters is exerted primarily during the S-phase of the cell cycle, and this effect is dose related.","Cell cycle kinetics of K2Cr2O7 exposed asynchronous cells characterized by DNA distribution analysis and the Brd-Urd Hoechst 33258-technique Abs: The effects of potassium-dichromate (7778509) (PD) on the cell cycle were tested in exponentially growing rat glioma cells. The cells were exposed to PD for various periods of time, detached by trypsination, centrifuged and stained. Analysis of the DNA histograms demonstrated that the mitosis of cells which were in late S-phase or G2 plus M-phase of the cycle at the start of the treatment with 1.0 micromolar PD was similar to that of controls. Linear delay of mitosis was evident with increasing PD exposure time during the S-phase; maximum delay was equal to 5 hours for early S-phase cells. Treatment with PD, during Gl phase, induced a delay in the cell cycle similar to that following exposure during the entire S-phase of the cells. In a concentration of 5 micromolar, PD was toxic to the cells. PD had no effect on the mitotic pattern of cells in G2 plus M-phase of the cycle 4 hours after exposure to 1 or 5 micromolar PD; these cells underwent mitosis similar to controls. The authors conclude that the effect of Cr on cell parameters is exerted primarily during the S-phase of the cell cycle, and this effect is dose related."
1238150,Goh et al. 1986,Occupational Dermatitis in a Prefabrication Construction Factory,"The causes of occupational dermatoses in a prefabrication construction factory were studied. Two hundred seventy two male workers were interviewed, examined, and patch tested with 0.5 percent potassium-dichromate (7778509), 1 percent cobalt-chloride (7646799), 5 percent nickel-sulfate (7786814), 1 percent thiuram mix, 3 percent carbamix, 2 percent mercapto mix, 1 percent epoxy resin, 0.6 percent PPD mix, 10 percent melanine formaldehyde, and 25 percent conplast. The overall prevalence of dermatoses was 16.9 percent, of which 14.0 percent were occupational and the rest were non occupational. Fifteen workers from the occupational cohort with dermatitis were allergic to chromate in cement, 22 had irritant contact dermatitis to cement, and one had allergic contact dermatitis to rubber chemicals. Two workers with non occupational contact dermatitis had allergic contact dermatitis to nickel in their watch and belt buckles. More than half who were allergic to chromium were employed in construction less than five years and were 20 to 29 years old. The sensitivity to chromate was not related to the duration of the job. The highest rate of chromate dermatitis was noticed among the workers in concreting bays. Clinical dermatitis was diagnosed in 15 of 23 workers with chromate allergy, four of these workers also had nickel sensitivity, and one worker had nickel dermatitis. One worker had asymptomatic epoxy resin sensitivity. Five workers were sensitive to nickel. Two that were exposed to nickel had no clinical dermatitis. In the majority of cases dermatitis was confined to arms. The authors conclude that the prevalence to chromate allergy was comparable to that in conventional construction practice.","Occupational Dermatitis in a Prefabrication Construction Factory Abs: The causes of occupational dermatoses in a prefabrication construction factory were studied. Two hundred seventy two male workers were interviewed, examined, and patch tested with 0.5 percent potassium-dichromate (7778509), 1 percent cobalt-chloride (7646799), 5 percent nickel-sulfate (7786814), 1 percent thiuram mix, 3 percent carbamix, 2 percent mercapto mix, 1 percent epoxy resin, 0.6 percent PPD mix, 10 percent melanine formaldehyde, and 25 percent conplast. The overall prevalence of dermatoses was 16.9 percent, of which 14.0 percent were occupational and the rest were non occupational. Fifteen workers from the occupational cohort with dermatitis were allergic to chromate in cement, 22 had irritant contact dermatitis to cement, and one had allergic contact dermatitis to rubber chemicals. Two workers with non occupational contact dermatitis had allergic contact dermatitis to nickel in their watch and belt buckles. More than half who were allergic to chromium were employed in construction less than five years and were 20 to 29 years old. The sensitivity to chromate was not related to the duration of the job. The highest rate of chromate dermatitis was noticed among the workers in concreting bays. Clinical dermatitis was diagnosed in 15 of 23 workers with chromate allergy, four of these workers also had nickel sensitivity, and one worker had nickel dermatitis. One worker had asymptomatic epoxy resin sensitivity. Five workers were sensitive to nickel. Two that were exposed to nickel had no clinical dermatitis. In the majority of cases dermatitis was confined to arms. The authors conclude that the prevalence to chromate allergy was comparable to that in conventional construction practice."
1238140,Tandon et al. 1986,Chemical Investigation of Welding Fumes from Hardfacing and HSLA-Steel Electrodes,"Detailed chemical analysis of the flux, fume, and water soluble fume fractions from three types of hardfacing and two types of high strength, low alloy (HSLA) shielded metal arc welding electrodes was performed. The five types of electrodes chosen for study are used extensively in the mining, chemical, and agriculture industries: hardfacing, medium chromium (7440473) (E01); HSLA steel (E04); HSLA steel direct current electrode positive; hardfacing, high manganese (7439965); and hardfacing, high chromium (E12). Analysis of electrode flux was carried out by x-ray fluorescence (XRF) and combustion. Fume from the electrodes was generated using an automatic arc welding machine. Analytical methods for evaluating fume included XRF, x-ray diffraction, atomic absorption spectrophotometry (AAS), ion selective electrode, and ion chromatography. Where elements were determined using both AAS and XRF techniques, agreement was excellent. In measuring water soluble fluorides by ion chromatography and ion select methods, variation was approximately +/10 percent, with ion chromatography probably the more accurate technique. Magnetite (1317619) and calcium-fluoride (7789755) were prominent in the crystal phases of four out of five fumes tested. Crystalline potassium-chromate (7789006) was present in fume from electrode E04, but absent from electrode E12. Up to 95 percent of total mass balances for flux, fume, and water soluble fume were obtained. An inverse relationship between fluoride (16984488) concentrations in fume and the fume generation rate was noted. Percentage of sodium (7440235) and potassium (7440097) in the flux was highly correlated with water soluble chromium(VI) (18540299) per total chromium in the fume. The authors conclude that guidance may be provided from this data for appraising the health status of welders, and situations related to fume exposure and toxicity.","Chemical Investigation of Welding Fumes from Hardfacing and HSLA-Steel Electrodes Abs: Detailed chemical analysis of the flux, fume, and water soluble fume fractions from three types of hardfacing and two types of high strength, low alloy (HSLA) shielded metal arc welding electrodes was performed. The five types of electrodes chosen for study are used extensively in the mining, chemical, and agriculture industries: hardfacing, medium chromium (7440473) (E01); HSLA steel (E04); HSLA steel direct current electrode positive; hardfacing, high manganese (7439965); and hardfacing, high chromium (E12). Analysis of electrode flux was carried out by x-ray fluorescence (XRF) and combustion. Fume from the electrodes was generated using an automatic arc welding machine. Analytical methods for evaluating fume included XRF, x-ray diffraction, atomic absorption spectrophotometry (AAS), ion selective electrode, and ion chromatography. Where elements were determined using both AAS and XRF techniques, agreement was excellent. In measuring water soluble fluorides by ion chromatography and ion select methods, variation was approximately +/10 percent, with ion chromatography probably the more accurate technique. Magnetite (1317619) and calcium-fluoride (7789755) were prominent in the crystal phases of four out of five fumes tested. Crystalline potassium-chromate (7789006) was present in fume from electrode E04, but absent from electrode E12. Up to 95 percent of total mass balances for flux, fume, and water soluble fume were obtained. An inverse relationship between fluoride (16984488) concentrations in fume and the fume generation rate was noted. Percentage of sodium (7440235) and potassium (7440097) in the flux was highly correlated with water soluble chromium(VI) (18540299) per total chromium in the fume. The authors conclude that guidance may be provided from this data for appraising the health status of welders, and situations related to fume exposure and toxicity."
1238137,Dooms-Goossens 1986,A Computerized Retrieval System of Contact Allergenic Substances,"A computerized retrieval system of patch test materials and methods for use in contact dermatitis was described. Patch tests were performed on 6818 patients applying the Belgian Tri Contact Standard Test Series, a modified International Contact Dermatology Research Group standard patch test series, supplemented with an occupational series, a pharmaceutical series, or patients own products. Of the 6818 patients, 64 percent were women. The most common professions were housekeeper, office worker, paramedic, cleaner, metal worker, needleworker, mechanic, cosmetologist, and cement worker. The main causal contact factors for the dermatitis reactions were occupational in 1826, iatrogenic in 1520, textile and accessories in 1421, housework in 943, cosmetics in 903, and hobbies in 372 patients. Allergic contact dermatitis was diagnosed in 3370, irritant contact dermatitis in 2037, photoallergic dermatitis in 36, and phototoxic dermatitis in 21 patients. Nickel-sulfate (7786814), balsam of Peru, cobalt-chloride (7646799), paraphenylenediamine (106503), and potassium-dichromate (7778509) were the most common allergens. Iatrogenic dermatitis occurred predominantly in older populations. Information on composition of pharmaceutical products has been stored in a computer file and periodically published on microfiche. Every chemical ingredient in pharmaceutical and cosmetic products has been assigned a code number; four physical parameters indicating the molecular weight, octanol/water partition coefficient, lipid solubility, and dissociation constant; and the acidic or alkaline nature of the ingredient. By coding for main constituents, metabolites, and impurities, a list was prepared of materials with possible cosensitivity and cross sensitivity.","A Computerized Retrieval System of Contact Allergenic Substances Abs: A computerized retrieval system of patch test materials and methods for use in contact dermatitis was described. Patch tests were performed on 6818 patients applying the Belgian Tri Contact Standard Test Series, a modified International Contact Dermatology Research Group standard patch test series, supplemented with an occupational series, a pharmaceutical series, or patients own products. Of the 6818 patients, 64 percent were women. The most common professions were housekeeper, office worker, paramedic, cleaner, metal worker, needleworker, mechanic, cosmetologist, and cement worker. The main causal contact factors for the dermatitis reactions were occupational in 1826, iatrogenic in 1520, textile and accessories in 1421, housework in 943, cosmetics in 903, and hobbies in 372 patients. Allergic contact dermatitis was diagnosed in 3370, irritant contact dermatitis in 2037, photoallergic dermatitis in 36, and phototoxic dermatitis in 21 patients. Nickel-sulfate (7786814), balsam of Peru, cobalt-chloride (7646799), paraphenylenediamine (106503), and potassium-dichromate (7778509) were the most common allergens. Iatrogenic dermatitis occurred predominantly in older populations. Information on composition of pharmaceutical products has been stored in a computer file and periodically published on microfiche. Every chemical ingredient in pharmaceutical and cosmetic products has been assigned a code number; four physical parameters indicating the molecular weight, octanol/water partition coefficient, lipid solubility, and dissociation constant; and the acidic or alkaline nature of the ingredient. By coding for main constituents, metabolites, and impurities, a list was prepared of materials with possible cosensitivity and cross sensitivity."
1238134,Stacey 1986,Effects of Cadmium and Zinc on Spontaneous and Antibody-Dependent Cell-Mediated Cytotoxicity,"The effects of cadmium (7440439) (Cd) and zinc (7440666) (Zn) on spontaneous cell mediated cytotoxicity (SCMC) and antibody dependent cell mediated cytotoxicity (ADCC) were investigated using Chang cells and K562 cells. Target cells were added to medium or lymphocyte suspension. Cadmium-chloride (10108642) and or zinc-sulfate (7446200) were added and cultures were incubated at 37 degrees-C for 4 hours. Both Cd and Zn inhibited ADCC. Cd at 25 micromolar (microM) and higher concentrations showed a dose dependent inhibition of killer (K) cell function, while Zn at 100 and 250microM was inhibitory. Cd and Zn together had an additive effect on K-cell function. SCMC was also inhibited by both Cd and Zn; the inhibition was also dose dependent with statistically significant responses at 100 and 250microM for each metal. The interaction between Cd and Zn inhibited SCMC additively. Screening of other metals for inhibitory effects on ADCC showed that lead (7439921), copper (7440508), and vanadium (7440622) had no consistent effects on K-cell function, while manganese (7439965) and potassium-chromate (7789006) depressed activity by about 50 percent at 250microM. Cobalt (7440484), nickel (7440020), and selenium (7782492) each reduced ADCC by approximately 20 percent. The author concludes that both Cd and Zn inhibit ADCC and SCMC in a dose dependent manner; that in combination their effects are generally additive; and that the concentration at which Cd was inhibitory suggests that an effect on ADCC is unlikely to be experienced in workers occupationally exposed to the metal at acceptable levels.","Effects of Cadmium and Zinc on Spontaneous and Antibody-Dependent Cell-Mediated Cytotoxicity Abs: The effects of cadmium (7440439) (Cd) and zinc (7440666) (Zn) on spontaneous cell mediated cytotoxicity (SCMC) and antibody dependent cell mediated cytotoxicity (ADCC) were investigated using Chang cells and K562 cells. Target cells were added to medium or lymphocyte suspension. Cadmium-chloride (10108642) and or zinc-sulfate (7446200) were added and cultures were incubated at 37 degrees-C for 4 hours. Both Cd and Zn inhibited ADCC. Cd at 25 micromolar (microM) and higher concentrations showed a dose dependent inhibition of killer (K) cell function, while Zn at 100 and 250microM was inhibitory. Cd and Zn together had an additive effect on K-cell function. SCMC was also inhibited by both Cd and Zn; the inhibition was also dose dependent with statistically significant responses at 100 and 250microM for each metal. The interaction between Cd and Zn inhibited SCMC additively. Screening of other metals for inhibitory effects on ADCC showed that lead (7439921), copper (7440508), and vanadium (7440622) had no consistent effects on K-cell function, while manganese (7439965) and potassium-chromate (7789006) depressed activity by about 50 percent at 250microM. Cobalt (7440484), nickel (7440020), and selenium (7782492) each reduced ADCC by approximately 20 percent. The author concludes that both Cd and Zn inhibit ADCC and SCMC in a dose dependent manner; that in combination their effects are generally additive; and that the concentration at which Cd was inhibitory suggests that an effect on ADCC is unlikely to be experienced in workers occupationally exposed to the metal at acceptable levels."
1238130,Snoeij et al. 1986,"Triorganotin-Induced Cytotoxicity To Rat Thymus, Bone Marrow And Red Blood Cells As Determined By Several In Vitro Assays","Triorganotin induced cytotoxicity was investigated in vitro. Male SPF-Wistar-rats were killed, thymocytes were isolated from thymus glands and hind leg bone marrow was removed. Trypan-blue (72571) exclusion was determined. Red blood cell suspensions were prepared and cultured. Cell count and trypan-blue exclusion were recorded up to 30 hours after addition of up to 8 micromolar (microM) trimethyltin-chloride (1066451) (TMTC), triethyltin-chloride (994310) (TETC), tri-n-propyltin-chloride (2279767) (TPTC), tri-n-butyltin-chloride (1461229) (TBTC), tri-n-hexyltin-chloride (2791608) (THTC), or triphenyltin-chloride (639587) (TPhTC). Thymocytes were cultured with triorganotin compounds and chromium-51 labeled sodium-chromate (7775113), hydrogen-3 labeled thymidine (50895), or prostaglandin-E1 (745653) and 3-isobutyl-1-methylxanthine (28822584). Chromium (7440473) release was calculated from chromium-51 radioactivity in supernatant. Labeled hydrogen-3 thymidine incorporation was counted. Cyclic adenosine-monophosphate (cAMP) was determined by protein bonding assay. TBTC cytotoxic effects on thymocytes, bone marrow cells, and red blood cells after incubation were compared. Approximately 84 percent of thymocyte control cultures survived 30 hours incubation; trypan-blue exclusion decreased to approximately 74 percent. Thymocyte trypan-blue exclusion capability decreased for triorganotins with concentration and time. The no effect concentration for all triorganotins tested for labeled chromium-51 release was 1microM, except for TMTC, which had no effect at any concentration tested. Thymidine incorporation decreased in a concentration dependent fashion. TPTC, TBTC, THTC, and TpHTC inhibited thymidine incorporation 40 to 60 percent between 0.1 and 1microM. TMTC decreased thymidine incorporation only at 8microM. TMTC and TETC did not influence cAMP induction at up to 8microM; TPhTC affected cAMP only at 8microM; and TPTC, TBTC, and THTC significantly decreased cAMP induction from 0.5microM. TBTC was most cytotoxic to thymocytes, followed by bone marrow cells, then red blood cells. The authors conclude that triorganotins are cytotoxic in vitro.","Triorganotin-Induced Cytotoxicity To Rat Thymus, Bone Marrow And Red Blood Cells As Determined By Several In Vitro Assays Abs: Triorganotin induced cytotoxicity was investigated in vitro. Male SPF-Wistar-rats were killed, thymocytes were isolated from thymus glands and hind leg bone marrow was removed. Trypan-blue (72571) exclusion was determined. Red blood cell suspensions were prepared and cultured. Cell count and trypan-blue exclusion were recorded up to 30 hours after addition of up to 8 micromolar (microM) trimethyltin-chloride (1066451) (TMTC), triethyltin-chloride (994310) (TETC), tri-n-propyltin-chloride (2279767) (TPTC), tri-n-butyltin-chloride (1461229) (TBTC), tri-n-hexyltin-chloride (2791608) (THTC), or triphenyltin-chloride (639587) (TPhTC). Thymocytes were cultured with triorganotin compounds and chromium-51 labeled sodium-chromate (7775113), hydrogen-3 labeled thymidine (50895), or prostaglandin-E1 (745653) and 3-isobutyl-1-methylxanthine (28822584). Chromium (7440473) release was calculated from chromium-51 radioactivity in supernatant. Labeled hydrogen-3 thymidine incorporation was counted. Cyclic adenosine-monophosphate (cAMP) was determined by protein bonding assay. TBTC cytotoxic effects on thymocytes, bone marrow cells, and red blood cells after incubation were compared. Approximately 84 percent of thymocyte control cultures survived 30 hours incubation; trypan-blue exclusion decreased to approximately 74 percent. Thymocyte trypan-blue exclusion capability decreased for triorganotins with concentration and time. The no effect concentration for all triorganotins tested for labeled chromium-51 release was 1microM, except for TMTC, which had no effect at any concentration tested. Thymidine incorporation decreased in a concentration dependent fashion. TPTC, TBTC, THTC, and TpHTC inhibited thymidine incorporation 40 to 60 percent between 0.1 and 1microM. TMTC decreased thymidine incorporation only at 8microM. TMTC and TETC did not influence cAMP induction at up to 8microM; TPhTC affected cAMP only at 8microM; and TPTC, TBTC, and THTC significantly decreased cAMP induction from 0.5microM. TBTC was most cytotoxic to thymocytes, followed by bone marrow cells, then red blood cells. The authors conclude that triorganotins are cytotoxic in vitro."
1238129,Borenfreund and  Puerner 1986,"Cytotoxicity Of Metals, Metal-Metal And Metal-Chelator Combinations Assayed In Vitro","An assay was developed to study the cytotoxicity of cationic and anionic metal salts on mouse fibroblasts. The assay was based on the spectrophotometrically determined absorbance of neutral-red (553242) stain incorporated into lysosomes. BALB/c-mouse fibroblasts were used as the target system. Cationic and anionic salts of metals were added before cultures attained confluency as dilutions over a range of 3 logs in 1:4 dilution steps. Test agents were removed after 24 hours for the addition of neutral red. The effects of the chelators ethylenediaminetetraacetic-acid (60004) (EDTA), nitrilotriacetic-acid (139139) (NTA) and 2,3-dimercaptosuccinic-acid (2418146) (DMSA) on cadmium (7440439) and copper (7440508) induced cell injury were also studied. In descending order of potency, the cationic metals were cadmium, mercury (7439976), silver (7440224), zinc (7440666), manganese (7439965), copper, nickel (7440020), and trivalent-chromium (16065831). In descending toxicity order, the anionic metals were potassium-dichromate (7778509), potassium-chromate (7789006), sodium-m-arsenite (7784465), sodium-arsenate (7631892), sodium-selenite (10102188), sodium-selenate (13410010), and potassium-permanganate (7722647). EDTA completely inhibited the cytotoxicity of cadmium. NTA was a partial inhibitor of cadmium induced cytotoxicity, but DMSA was not effective. The reduction of copper toxicity was less efficient. The authors conclude that the neutral-red assay can be valuable for screening cytotoxic and potentially therapeutic agents in vitro.","Cytotoxicity Of Metals, Metal-Metal And Metal-Chelator Combinations Assayed In Vitro Abs: An assay was developed to study the cytotoxicity of cationic and anionic metal salts on mouse fibroblasts. The assay was based on the spectrophotometrically determined absorbance of neutral-red (553242) stain incorporated into lysosomes. BALB/c-mouse fibroblasts were used as the target system. Cationic and anionic salts of metals were added before cultures attained confluency as dilutions over a range of 3 logs in 1:4 dilution steps. Test agents were removed after 24 hours for the addition of neutral red. The effects of the chelators ethylenediaminetetraacetic-acid (60004) (EDTA), nitrilotriacetic-acid (139139) (NTA) and 2,3-dimercaptosuccinic-acid (2418146) (DMSA) on cadmium (7440439) and copper (7440508) induced cell injury were also studied. In descending order of potency, the cationic metals were cadmium, mercury (7439976), silver (7440224), zinc (7440666), manganese (7439965), copper, nickel (7440020), and trivalent-chromium (16065831). In descending toxicity order, the anionic metals were potassium-dichromate (7778509), potassium-chromate (7789006), sodium-m-arsenite (7784465), sodium-arsenate (7631892), sodium-selenite (10102188), sodium-selenate (13410010), and potassium-permanganate (7722647). EDTA completely inhibited the cytotoxicity of cadmium. NTA was a partial inhibitor of cadmium induced cytotoxicity, but DMSA was not effective. The reduction of copper toxicity was less efficient. The authors conclude that the neutral-red assay can be valuable for screening cytotoxic and potentially therapeutic agents in vitro."
1238127,De Vuyst et al. 1986,Dental Technician's Pneumoconiosis. A Report Of Two Cases,"Two cases of pneumoconiosis in dental technicians (SIC-8021) were described. The first case was a 49 year old male who was seen because a routine chest X-ray showed a diffuse reticulonodular infiltration predominating in both upper lobes with a biapical pleural thickening. He had a smoking history of 3.5 pack-years, but had given up smoking 15 years previously, and had no past history of respiratory illness other than a right spontaneous pneumothorax. He had been employed as a dental technician for 31 years, primarily molding, cutting, and polishing prosthetic parts made of Vitallium, a chromium/cobalt/molybdenum alloy. Bronchoalveolar lavage was performed and a surgical lung biopsy was performed. Detailed mineralogical analysis of the lavage fluid and biopsy tissue found Vitallium particles as well as silicon-carbide, talc, and chromium-oxide. Asbestos fibers and asbestos bodies were also found in the lavage fluid. Histologically, the lung appeared irregularly fibrotic. The patient stopped work 2 years later and was reexamined a year after that. A chest X-ray showed progression of the disease with retraction of both upper lung lobes. Pulmonary function tests showed a decrease in vital capacity and lung compliance. The second case was a 30 year old female who was seen for evaluation of a dry cough. She worked half time for 7 years in a dental laboratory sand blasting Vitallium prosthetic parts. She was a previous light smoker. A chest X-ray showed a diffuse reticulonodular infiltration primarily in the upper lobes. Lung function tests were normal. Bronchoalveolar lavage disclosed Vitallium particles as well as iron, iron/chromium, and silica particles. No asbestos was found. The authors suggest that the patients have a form of pneumoconiosis differing from other pneumoconioses such as silicosis, hard metal disease, or asbestosis. Chromium/cobalt/molybdenum alloys might play a central role in the genesis of the disease.","Dental Technician's Pneumoconiosis. A Report Of Two Cases Abs: Two cases of pneumoconiosis in dental technicians (SIC-8021) were described. The first case was a 49 year old male who was seen because a routine chest X-ray showed a diffuse reticulonodular infiltration predominating in both upper lobes with a biapical pleural thickening. He had a smoking history of 3.5 pack-years, but had given up smoking 15 years previously, and had no past history of respiratory illness other than a right spontaneous pneumothorax. He had been employed as a dental technician for 31 years, primarily molding, cutting, and polishing prosthetic parts made of Vitallium, a chromium/cobalt/molybdenum alloy. Bronchoalveolar lavage was performed and a surgical lung biopsy was performed. Detailed mineralogical analysis of the lavage fluid and biopsy tissue found Vitallium particles as well as silicon-carbide, talc, and chromium-oxide. Asbestos fibers and asbestos bodies were also found in the lavage fluid. Histologically, the lung appeared irregularly fibrotic. The patient stopped work 2 years later and was reexamined a year after that. A chest X-ray showed progression of the disease with retraction of both upper lung lobes. Pulmonary function tests showed a decrease in vital capacity and lung compliance. The second case was a 30 year old female who was seen for evaluation of a dry cough. She worked half time for 7 years in a dental laboratory sand blasting Vitallium prosthetic parts. She was a previous light smoker. A chest X-ray showed a diffuse reticulonodular infiltration primarily in the upper lobes. Lung function tests were normal. Bronchoalveolar lavage disclosed Vitallium particles as well as iron, iron/chromium, and silica particles. No asbestos was found. The authors suggest that the patients have a form of pneumoconiosis differing from other pneumoconioses such as silicosis, hard metal disease, or asbestosis. Chromium/cobalt/molybdenum alloys might play a central role in the genesis of the disease."
1238123,Miyachi et al. 1985,Pemphigoid Following Chronic Cement Dermatitis,"The case was described of a 71 year old man, a former construction worker, with a 15 year history of chronic contact dermatitis which was probably induced by metal ions present in Portland cement, who was treated effectively with topical corticosteroids. Previous patch tests revealed positive reactions to 2 percent cobalt-chloride (7646799) and 0.5 percent potassium-dichromate (7778509) and histological evidence of acanthosis. At the last examination, prompted by the sudden appearance of severe tense erythematous bullae on the limbs, face and trunk, biopsy revealed subepidermal bullae with eosinophils, fibrin and perivascular accumulation of eosinophils, mononuclear cells and neutrophils. Direct immunofluorescence demonstrated the presence of immunoglobulin-G, complement-factor-3 and fibrinogen at the basement membrane zone, while indirect immunofluorescence showed antibasement membrane zone antibodies. Since the findings were compatible with a diagnosis of pemphigoid, the patient was placed first on betamethasone, starting at 5 milligrams daily and then gradually decreasing, and then on dapsone, initially in a dose of 75 milligrams and then 50 milligrams daily, which was discontinued despite the fact that blisters continued to appear and there was continuing evidence of persistent pemphigoid following the clearance of the skin lesions. The authors conclude that the late bullous lesions are not related to the cement contact dermatitis history of the patient.","Pemphigoid Following Chronic Cement Dermatitis Abs: The case was described of a 71 year old man, a former construction worker, with a 15 year history of chronic contact dermatitis which was probably induced by metal ions present in Portland cement, who was treated effectively with topical corticosteroids. Previous patch tests revealed positive reactions to 2 percent cobalt-chloride (7646799) and 0.5 percent potassium-dichromate (7778509) and histological evidence of acanthosis. At the last examination, prompted by the sudden appearance of severe tense erythematous bullae on the limbs, face and trunk, biopsy revealed subepidermal bullae with eosinophils, fibrin and perivascular accumulation of eosinophils, mononuclear cells and neutrophils. Direct immunofluorescence demonstrated the presence of immunoglobulin-G, complement-factor-3 and fibrinogen at the basement membrane zone, while indirect immunofluorescence showed antibasement membrane zone antibodies. Since the findings were compatible with a diagnosis of pemphigoid, the patient was placed first on betamethasone, starting at 5 milligrams daily and then gradually decreasing, and then on dapsone, initially in a dose of 75 milligrams and then 50 milligrams daily, which was discontinued despite the fact that blisters continued to appear and there was continuing evidence of persistent pemphigoid following the clearance of the skin lesions. The authors conclude that the late bullous lesions are not related to the cement contact dermatitis history of the patient."
1238121,Y-L and  X-H 1985,Occupational Health of Working Women in China,"The history of working conditions and occupational health of female workers in China and improvements which have been made were presented. In 1954, the average air lead (7439921) level in a privately owned lead plant was 1000 times the current standard, and all female employees were found to have lead poisoning. Lead poisoning was no longer found among employees after the plant merged into a government enterprise. Females were found to be more sensitive to lead poisoning than were men. Rates of threatened abortions were significantly higher among female workers exposed to lead-chromate (7758976), and nursing babies of mothers with lead poisoning were diagnosed as having lead poisoning. In the early sixties, female spinners in rayon factories exposed to carbon-disulfide (75150) (CS2) had a high incidence of menstrual disturbances and preeclampsia; CS2 was found in cord blood, breast milk, and urine of nursing babies. The incidences of spontaneous abortions and congenital defects of offspring were significantly higher among female workers exposed to CS2 than among comparisons, even among those exposed to levels less than the current standard, indicating the need to lower the standard. Exposure to levels of vinyl-chloride (75014) higher than the health standard was found to increase the incidence of hypertensive disorders in pregnancy; no adverse effects were found with exposure to levels lower than the standard. Retired female weavers, who had been exposed to high levels of noise pollution were found to suffer from occupational deafness and adverse neurologic effects. The prevalence of byssinosis was found to be more than twice as high among females than males employed in the same cotton mill. Heavy physical labor was found to greatly increase the incidences of menstrual disturbance, abortion, stillbirth and prolapse of the uterus. The authors conclude that although improvements have been made in occupational health of female workers in China, there remains much need for research and interventions in this area.","Occupational Health of Working Women in China Abs: The history of working conditions and occupational health of female workers in China and improvements which have been made were presented. In 1954, the average air lead (7439921) level in a privately owned lead plant was 1000 times the current standard, and all female employees were found to have lead poisoning. Lead poisoning was no longer found among employees after the plant merged into a government enterprise. Females were found to be more sensitive to lead poisoning than were men. Rates of threatened abortions were significantly higher among female workers exposed to lead-chromate (7758976), and nursing babies of mothers with lead poisoning were diagnosed as having lead poisoning. In the early sixties, female spinners in rayon factories exposed to carbon-disulfide (75150) (CS2) had a high incidence of menstrual disturbances and preeclampsia; CS2 was found in cord blood, breast milk, and urine of nursing babies. The incidences of spontaneous abortions and congenital defects of offspring were significantly higher among female workers exposed to CS2 than among comparisons, even among those exposed to levels less than the current standard, indicating the need to lower the standard. Exposure to levels of vinyl-chloride (75014) higher than the health standard was found to increase the incidence of hypertensive disorders in pregnancy; no adverse effects were found with exposure to levels lower than the standard. Retired female weavers, who had been exposed to high levels of noise pollution were found to suffer from occupational deafness and adverse neurologic effects. The prevalence of byssinosis was found to be more than twice as high among females than males employed in the same cotton mill. Heavy physical labor was found to greatly increase the incidences of menstrual disturbance, abortion, stillbirth and prolapse of the uterus. The authors conclude that although improvements have been made in occupational health of female workers in China, there remains much need for research and interventions in this area."
1238120,De Flora et al. 1985,Distinctive mechanisms for interaction of hexavalent and trivalent chromium with DNA?,"The genotoxicity of hexavalent chromium (18540299) (Cr(VI)) and trivalent chromium (16065831) (Cr(III)) compounds was studied in-vitro. Sodium-dichromate (10588019), potassium-chromate (7789006), calcium-chromate (13765190), ammonium-chromate (7788898), chromium-trioxide (1333820), chromic-nitrate (13548384), chromic-chloride (10025737), chromic-potassium-sulfate (10141001), and chromic-acetate (1066304) were tested for mutagenic activity in the Amesalmonella assay system and for DNA repair in Escherichia-coli in the presence or absence of metabolic activation with S9 mix. Strains (TA-98), (TA-1535), (TA-100), (TA-1538), (TA-1537), and (TA-97) were used in the Ames/Salmonella test. All of the Cr(III) compounds were negative in the Ames/Salmonella system, whereas all of the Cr(VI) compounds showed mutagenic activity. All Cr(VI) compounds inhibited DNA repair. The Cr(III) compounds did not induce DNA damage in Escherichia-coli except after long preincubation at mildly alkaline pH 7.4. Long preincubation at pH 7.4 did not reveal any mutagenicity of Cr(III). The authors conclude that the genotoxicity of Cr(VI) is due to its ability to decrease the fidelity of DNA synthesis by unbalancing nucleotide pools and inducing single strand DNA breaks. Cr(III) induces DNA/protein and DNA/DNA crosslinks and reduces the fidelity of DNA replication by complexing nucleophilic sites in DNA, precursor nucleotides, or DNA polymerases.","Distinctive mechanisms for interaction of hexavalent and trivalent chromium with DNA? Abs: The genotoxicity of hexavalent chromium (18540299) (Cr(VI)) and trivalent chromium (16065831) (Cr(III)) compounds was studied in-vitro. Sodium-dichromate (10588019), potassium-chromate (7789006), calcium-chromate (13765190), ammonium-chromate (7788898), chromium-trioxide (1333820), chromic-nitrate (13548384), chromic-chloride (10025737), chromic-potassium-sulfate (10141001), and chromic-acetate (1066304) were tested for mutagenic activity in the Amesalmonella assay system and for DNA repair in Escherichia-coli in the presence or absence of metabolic activation with S9 mix. Strains (TA-98), (TA-1535), (TA-100), (TA-1538), (TA-1537), and (TA-97) were used in the Ames/Salmonella test. All of the Cr(III) compounds were negative in the Ames/Salmonella system, whereas all of the Cr(VI) compounds showed mutagenic activity. All Cr(VI) compounds inhibited DNA repair. The Cr(III) compounds did not induce DNA damage in Escherichia-coli except after long preincubation at mildly alkaline pH 7.4. Long preincubation at pH 7.4 did not reveal any mutagenicity of Cr(III). The authors conclude that the genotoxicity of Cr(VI) is due to its ability to decrease the fidelity of DNA synthesis by unbalancing nucleotide pools and inducing single strand DNA breaks. Cr(III) induces DNA/protein and DNA/DNA crosslinks and reduces the fidelity of DNA replication by complexing nucleophilic sites in DNA, precursor nucleotides, or DNA polymerases."
1238119,Richelmi et al. 1984,"Blood levels of hexavalent chromium in rats. ""In vitro"" and ""In vivo"" experiments","For the Cr(VI) selective separation from biological materials we have developed a highly rapid extraction-separation method with liquid anion exchanger as Amberlite LA-1 or LA-2. The analytical determination of Cr(VI) in organic phase was carried out using electrothermal atomic absorption spectroscopy (ETA-AAS). After i.v. administration of 0.5 and 2.5 mg/kg b.w. of K2Cr2O7 in male Wistar rats the biological samples, collected at different times, were immediately analyzed. Cr(VI) was not detected in whole blood one minute after administration of the lower dose. In blood of rats receiving higher dose an incomplete reduction of Cr(VI) was observed. Such data demonstrate a highly rapid but limited metabolic capacity of hematic compartment to reduce Cr(VI) to trivalent status. ""In vitro"" incubation of K2Cr2O7 (4 microM) with rat erythrocytes or plasma at 37 degrees C showed a rapid reduction of Cr(VI) in red cells while plasma samples demonstrated a limited reductive power. These results obtained with a new and specific analytical method, confirmed a trigger role of red cells in Cr(VI) metabolism.","Blood levels of hexavalent chromium in rats. ""In vitro"" and ""In vivo"" experiments Abs: For the Cr(VI) selective separation from biological materials we have developed a highly rapid extraction-separation method with liquid anion exchanger as Amberlite LA-1 or LA-2. The analytical determination of Cr(VI) in organic phase was carried out using electrothermal atomic absorption spectroscopy (ETA-AAS). After i.v. administration of 0.5 and 2.5 mg/kg b.w. of K2Cr2O7 in male Wistar rats the biological samples, collected at different times, were immediately analyzed. Cr(VI) was not detected in whole blood one minute after administration of the lower dose. In blood of rats receiving higher dose an incomplete reduction of Cr(VI) was observed. Such data demonstrate a highly rapid but limited metabolic capacity of hematic compartment to reduce Cr(VI) to trivalent status. ""In vitro"" incubation of K2Cr2O7 (4 microM) with rat erythrocytes or plasma at 37 degrees C showed a rapid reduction of Cr(VI) in red cells while plasma samples demonstrated a limited reductive power. These results obtained with a new and specific analytical method, confirmed a trigger role of red cells in Cr(VI) metabolism."
1238116,Santodonato et al. 1985,Final report: Monograph on human exposure to chemicals in the workplace: Zinc chromate,"A National Cancer Institute monograph on occupational hazards of zinc-chromate (14018952) is presented. Chemical and physical properties of zinc-chromate are summarized. Production and uses of zinc-chromate are described. The commercially important forms of zinc-chromate are basic zinc-chromate (13530659) and zinc-yellow-chromate (37300235); both contain chromium in the hexavalent oxidation state and are used almost exclusively as corrosion inhibitors in mixed paints and as primer coats for steel and aluminum. Occupational exposure is discussed. Estimates of workers currently exposed to zinc chromates are not available, however, exposure is expected to be widespread since multimillion pound quantities of zinc chromates are consumed annually. Available data indicate that airborne chromate exposures on the order of 0.01 to 1.35 milligrams per cubic meter can occur during production of chromium containing pigments. Pharmacokinetic data are reviewed. Systemic absorption occurs following inhalation of zinc-chromate dust. In-vitro studies have shown that hexavalent chromium accumulates in erythrocytes, where it is reduced to trivalent chromium. Biological data relevant to carcinogenesis and mutagenesis are reviewed. Lung tumors have been induced by zinc chromates and other hexavalent chromium compounds in laboratory animals and zinc-chromate has shown mutagenic activity in bacterial test systems. Epidemiologic studies have shown an increased incidence of lung cancer among chromate pigment workers, however, the number of cancer cases was small and the concentrations of zinc-chromate were not known. The authors conclude that exposure to zinc chromates appears to be associated with an increased cancer risk.","Final report: Monograph on human exposure to chemicals in the workplace: Zinc chromate Abs: A National Cancer Institute monograph on occupational hazards of zinc-chromate (14018952) is presented. Chemical and physical properties of zinc-chromate are summarized. Production and uses of zinc-chromate are described. The commercially important forms of zinc-chromate are basic zinc-chromate (13530659) and zinc-yellow-chromate (37300235); both contain chromium in the hexavalent oxidation state and are used almost exclusively as corrosion inhibitors in mixed paints and as primer coats for steel and aluminum. Occupational exposure is discussed. Estimates of workers currently exposed to zinc chromates are not available, however, exposure is expected to be widespread since multimillion pound quantities of zinc chromates are consumed annually. Available data indicate that airborne chromate exposures on the order of 0.01 to 1.35 milligrams per cubic meter can occur during production of chromium containing pigments. Pharmacokinetic data are reviewed. Systemic absorption occurs following inhalation of zinc-chromate dust. In-vitro studies have shown that hexavalent chromium accumulates in erythrocytes, where it is reduced to trivalent chromium. Biological data relevant to carcinogenesis and mutagenesis are reviewed. Lung tumors have been induced by zinc chromates and other hexavalent chromium compounds in laboratory animals and zinc-chromate has shown mutagenic activity in bacterial test systems. Epidemiologic studies have shown an increased incidence of lung cancer among chromate pigment workers, however, the number of cancer cases was small and the concentrations of zinc-chromate were not known. The authors conclude that exposure to zinc chromates appears to be associated with an increased cancer risk."
1238113,Rana et al. 1985,A Study Of Glycogen In The Liver Of Metal-Fed Rats,"The effect of inorganic compounds on liver injury resulting from disorders of carbohydrate metabolism was investigated. Male albino-rats, 90 days old, were divided into ten groups of ten rats. Rats were acclimated to laboratory conditions before they were fed sublethal doses of mercury-nitrate (10045940), lead-nitrate (10099748), cadmium-sulfate (10124364), ammonium-molybdate (11098843), copper-sulfate, zinc-acetate (557346), potassium-chromate (7789006), manganese-chloride (7773015), and cobalt-acetate (71487) for 30 days. Rats were fasted overnight before sacrifice. Body/liver weight ratios were recorded, and thin slices of liver were removed for determination of glycogen. All of the metals, except zinc-acetate and copper-sulfate, caused depletion of glycogen in the liver. Molybdenum (7439987), chromium (7440473), and manganese (7439965) salts produced the lowest values of liver glycogen. Zinc (7440666) was a better stimulator of glycogen storage than was copper (7440508). The stimulatory effects of zinc and copper were attributed to their ability to induce enzymes active in gluconeogenesis. The authors conclude that the deviation from normal liver glycolysis and glycogen metabolism arises from chronic administration of metal salts.","A Study Of Glycogen In The Liver Of Metal-Fed Rats Abs: The effect of inorganic compounds on liver injury resulting from disorders of carbohydrate metabolism was investigated. Male albino-rats, 90 days old, were divided into ten groups of ten rats. Rats were acclimated to laboratory conditions before they were fed sublethal doses of mercury-nitrate (10045940), lead-nitrate (10099748), cadmium-sulfate (10124364), ammonium-molybdate (11098843), copper-sulfate, zinc-acetate (557346), potassium-chromate (7789006), manganese-chloride (7773015), and cobalt-acetate (71487) for 30 days. Rats were fasted overnight before sacrifice. Body/liver weight ratios were recorded, and thin slices of liver were removed for determination of glycogen. All of the metals, except zinc-acetate and copper-sulfate, caused depletion of glycogen in the liver. Molybdenum (7439987), chromium (7440473), and manganese (7439965) salts produced the lowest values of liver glycogen. Zinc (7440666) was a better stimulator of glycogen storage than was copper (7440508). The stimulatory effects of zinc and copper were attributed to their ability to induce enzymes active in gluconeogenesis. The authors conclude that the deviation from normal liver glycolysis and glycogen metabolism arises from chronic administration of metal salts."
1238112,Lazzarini et al. 1985,Effects Of Chromium(VI) And Chromium(III) On Energy Charge And Oxygen Consumption In Rat Thymocytes,"The cytotoxic effects of hexavalent-chromium (18540299) (Cr+6) and trivalent-chromium (16065831) (Cr+3) were studied in-vitro. Rat thymocytes and liver mitochrondria were incubated with 0 to 1.000 millimolar (mM) potassium-dichromate (7778509) or 0 to 1.000mM chromium(III)-oxide (11118573). The effects on endogenous nucleotide pools and adenylate charge, and basal and p-trifluoromethoxyphenylhydrazone stimulated oxygen consumption were evaluated. Some of the thymocytes had been treated with digitonin (11024241). The adenylate energy charge of rat thymocytes was significantly decreased after 10 minutes of incubation with 1.000mM potassium-dichromate. Cr+6 induced a marked inbalance in the purine nucleotide pool. Incubation with 1.000mM Cr+3 for up to 20 minutes had no effect on the energy charge. Cr+6, but not Cr+3, decreased basal and stimulated oxygen consumption. Cr+6 and Cr+3 inhibited stimulated rat liver mitochondrial oxygen consumption. The dose/response depended on substrate. With succinate as substrate, Cr+6 and Cr+3 inhibited oxygen consumption equally. With glutamate plus malate as substrate, Cr+6 was about 300 times more effective than Cr+3. In rat thymocytes treated with digitonin, Cr+6 and Cr+3 both caused a significant inhibition of maximal oxygen consumption. Cr+6 was more effective when glutamate plus malate was the substrate and Cr+3 was more effective when succinate was the substrate. The authors suggest that inhibition of mitochondrial oxidative phosphorylation is one of the primary targets of chromium cytotoxicity.","Effects Of Chromium(VI) And Chromium(III) On Energy Charge And Oxygen Consumption In Rat Thymocytes Abs: The cytotoxic effects of hexavalent-chromium (18540299) (Cr+6) and trivalent-chromium (16065831) (Cr+3) were studied in-vitro. Rat thymocytes and liver mitochrondria were incubated with 0 to 1.000 millimolar (mM) potassium-dichromate (7778509) or 0 to 1.000mM chromium(III)-oxide (11118573). The effects on endogenous nucleotide pools and adenylate charge, and basal and p-trifluoromethoxyphenylhydrazone stimulated oxygen consumption were evaluated. Some of the thymocytes had been treated with digitonin (11024241). The adenylate energy charge of rat thymocytes was significantly decreased after 10 minutes of incubation with 1.000mM potassium-dichromate. Cr+6 induced a marked inbalance in the purine nucleotide pool. Incubation with 1.000mM Cr+3 for up to 20 minutes had no effect on the energy charge. Cr+6, but not Cr+3, decreased basal and stimulated oxygen consumption. Cr+6 and Cr+3 inhibited stimulated rat liver mitochondrial oxygen consumption. The dose/response depended on substrate. With succinate as substrate, Cr+6 and Cr+3 inhibited oxygen consumption equally. With glutamate plus malate as substrate, Cr+6 was about 300 times more effective than Cr+3. In rat thymocytes treated with digitonin, Cr+6 and Cr+3 both caused a significant inhibition of maximal oxygen consumption. Cr+6 was more effective when glutamate plus malate was the substrate and Cr+3 was more effective when succinate was the substrate. The authors suggest that inhibition of mitochondrial oxidative phosphorylation is one of the primary targets of chromium cytotoxicity."
1238105,Brigham and  Landrigan 1985,Safety And Health In Boatbuilding And Repair,"The occupational safety and health hazards of boat building and repair (SIC-3732) are discussed. The boat building industry employs a large number of employees who work in many small shops. The basic construction materials of boats are fiberglass, reinforced plastic, wood or metal. Rates of occupational injury and illness are high. These include falls, lacerations, low back injury, repetitive motion injury, and noise exposure. Exposure to hazardous materials occur during construction and exposure in the process of welding, painting, and pouring lead. Abrasions and rubbing accidents are the most common types of injury. Musculoskeletal injury, intense noise exposure, and fire and explosion are some of the hazards involved. Exposure to toluene (108883), polyester resin systems, styrene (100425), wood dust, methyl-ethyl-ketone (1338234), and fibrous glass also occurs. A small number of workers are exposed to lead-chromate (7758976), asbestos (1332214), and formaldehyde (50000). Some diseases related to exposure to these chemicals are described, including skin irritation, respiratory disease, and neoplasms. Some preventive measures involve engineering controls such as ventilation. Use of personal protective equipment, personnel education, medical surveillance and first aid facilities, and development of fire fighting plans are discussed. The authors conclude that strong hazard control programs will provide health and economic benefits in the boat building industry.","Safety And Health In Boatbuilding And Repair Abs: The occupational safety and health hazards of boat building and repair (SIC-3732) are discussed. The boat building industry employs a large number of employees who work in many small shops. The basic construction materials of boats are fiberglass, reinforced plastic, wood or metal. Rates of occupational injury and illness are high. These include falls, lacerations, low back injury, repetitive motion injury, and noise exposure. Exposure to hazardous materials occur during construction and exposure in the process of welding, painting, and pouring lead. Abrasions and rubbing accidents are the most common types of injury. Musculoskeletal injury, intense noise exposure, and fire and explosion are some of the hazards involved. Exposure to toluene (108883), polyester resin systems, styrene (100425), wood dust, methyl-ethyl-ketone (1338234), and fibrous glass also occurs. A small number of workers are exposed to lead-chromate (7758976), asbestos (1332214), and formaldehyde (50000). Some diseases related to exposure to these chemicals are described, including skin irritation, respiratory disease, and neoplasms. Some preventive measures involve engineering controls such as ventilation. Use of personal protective equipment, personnel education, medical surveillance and first aid facilities, and development of fire fighting plans are discussed. The authors conclude that strong hazard control programs will provide health and economic benefits in the boat building industry."
1238104,Ruiz-Rubio et al. 1985,Oxidative mutagens specific for A-T base pairs induce forward mutations to L-arabinose resistance in Salmonella typhimurium,"Strain TA102 of S. typhimurium is a new histidine-requiring mutant, particularly suited to the detection of oxidative mutagens acting at A·T base pairs. 10 oxidizing chemicals, previously tested in strain TA102, were used to evaluate the mutagenic sensitivity of the L-arabinose forward mutation assay of S. typhimurium with respect to those types of mutagens. The mutagenicity of each compound was determined by liquid test, measuring both the frequency of mutants among the survivors and the absolute number of mutants growing in selective plates with traces of D-glucose. Strain BA13 with a wild-type lipopolysaccharide barrier was used as compared to the deep rough derivative strain BA9. The chemicals studied were: bleomycin, t-butyl hydroperoxide, chromium trioxide, cumeme hydroperoxide, formaldehyde, glyoxal, glutaraldehyde, hydrogen peroxide, paraquat, and phenylhydrazine. Additionally, ultrasonic oscillation was used as a presumable non-mutagenic lethal control treatment. The L-arabinose forward mutation assay detected the mutagenic activity of all the chemicals under study with a high degree of sensitivity, including paraquat which is unable to revert strain TA102. Positive responses were obtained at doses equivalent to or 10 times lower than the doses detected by strain TA102. The results support the idea that the L-arabinose forward mutation assay could replace the set of specific tester strains used by the histidine reverse mutation assay in general screening for genetic toxins.","Oxidative mutagens specific for A-T base pairs induce forward mutations to L-arabinose resistance in Salmonella typhimurium Abs: Strain TA102 of S. typhimurium is a new histidine-requiring mutant, particularly suited to the detection of oxidative mutagens acting at A·T base pairs. 10 oxidizing chemicals, previously tested in strain TA102, were used to evaluate the mutagenic sensitivity of the L-arabinose forward mutation assay of S. typhimurium with respect to those types of mutagens. The mutagenicity of each compound was determined by liquid test, measuring both the frequency of mutants among the survivors and the absolute number of mutants growing in selective plates with traces of D-glucose. Strain BA13 with a wild-type lipopolysaccharide barrier was used as compared to the deep rough derivative strain BA9. The chemicals studied were: bleomycin, t-butyl hydroperoxide, chromium trioxide, cumeme hydroperoxide, formaldehyde, glyoxal, glutaraldehyde, hydrogen peroxide, paraquat, and phenylhydrazine. Additionally, ultrasonic oscillation was used as a presumable non-mutagenic lethal control treatment. The L-arabinose forward mutation assay detected the mutagenic activity of all the chemicals under study with a high degree of sensitivity, including paraquat which is unable to revert strain TA102. Positive responses were obtained at doses equivalent to or 10 times lower than the doses detected by strain TA102. The results support the idea that the L-arabinose forward mutation assay could replace the set of specific tester strains used by the histidine reverse mutation assay in general screening for genetic toxins."
1238102,Venier et al. 1985,Effects Of Nitrilotriacetic Acid On The Induction Of Gene Mutations And Sister-Chromatid Exchanges By Insoluble Chromium Compounds,"The effects of nitrilotriacetic-acid (139139) (NTA) on chromium (7440473) mutagenicity and clastogenicity were investigated. Salmonella microassay (plate test strain TA-100) was carried out in the presence or absence of a metabolic activation system (rat liver S9 mix fraction). The pseudodiploid Chinese-hamster ovary (CHO) fibroblast line was used to detect sister chromatid exchange (SCE). Chromium compounds were suspended in water, 0.5 normal sodium-hydroxide, or NTA. The compounds were added at the same time as bromodeoxyuridine. During the last 4 hours of suspension, 0.4 microgram per milliliter of colchicine was added. At the end of treatment, the cells were fixed, stained, and scored for SCE. Lead-chromate (7758976), and barium-chromate (10294403) were neither mutagenic nor toxic in water, while calcium-chromate (13765190), strontium-chromate (7789062), and zinc-chromate (13530659) (all partially water soluble) induced a dose related mutagenic response. Zinc-chromate was also toxic at the highest concentrations tested. When suspended in alkali or in increasing concentrations of NTA, the very insoluble lead-chromate became mutagenic, while barium-chromate was made active only by NTA. A slight increase in the number of revertant colonies was produced when chromite (1308312) was tested on TA-100 in the presence of NTA. SCE was detected in CHO cells treated with barium-chromate, strontium-chromate, calcium-chromate, and zinc-chromate, and with three very insoluble industrial pigments, zinc-yellow (11103869), chromium-yellow (7758976) and molybdenum-orange. The authors conclude that NTA elicits or enhances both the direct mutagenic activity of several insoluble chromium(VI) compounds, and their ability to induce SCE in CHO cells.","Effects Of Nitrilotriacetic Acid On The Induction Of Gene Mutations And Sister-Chromatid Exchanges By Insoluble Chromium Compounds Abs: The effects of nitrilotriacetic-acid (139139) (NTA) on chromium (7440473) mutagenicity and clastogenicity were investigated. Salmonella microassay (plate test strain TA-100) was carried out in the presence or absence of a metabolic activation system (rat liver S9 mix fraction). The pseudodiploid Chinese-hamster ovary (CHO) fibroblast line was used to detect sister chromatid exchange (SCE). Chromium compounds were suspended in water, 0.5 normal sodium-hydroxide, or NTA. The compounds were added at the same time as bromodeoxyuridine. During the last 4 hours of suspension, 0.4 microgram per milliliter of colchicine was added. At the end of treatment, the cells were fixed, stained, and scored for SCE. Lead-chromate (7758976), and barium-chromate (10294403) were neither mutagenic nor toxic in water, while calcium-chromate (13765190), strontium-chromate (7789062), and zinc-chromate (13530659) (all partially water soluble) induced a dose related mutagenic response. Zinc-chromate was also toxic at the highest concentrations tested. When suspended in alkali or in increasing concentrations of NTA, the very insoluble lead-chromate became mutagenic, while barium-chromate was made active only by NTA. A slight increase in the number of revertant colonies was produced when chromite (1308312) was tested on TA-100 in the presence of NTA. SCE was detected in CHO cells treated with barium-chromate, strontium-chromate, calcium-chromate, and zinc-chromate, and with three very insoluble industrial pigments, zinc-yellow (11103869), chromium-yellow (7758976) and molybdenum-orange. The authors conclude that NTA elicits or enhances both the direct mutagenic activity of several insoluble chromium(VI) compounds, and their ability to induce SCE in CHO cells."
1238101,Alomar et al. 1985,Occupational Dermatoses From Cutting Oils,"Occupational dermatitis caused by various cutting oils was studied in 230 metallurgical workers. The subjects were surveyed by an extensive occupational and medical questionnaire. They were also given a series of patch tests to observe their responses to exposure to a standard series of oils and allergens. Paraphenylenediamine (106503) caused the highest percentage of positive responses, followed by potassium-dichromate (7778509), cobalt-chloride (1332827), thiuram (137268) mix, wood alcohols, formaldehyde (50000), neomycin (1404042), colophony (8050097), mercapto mix, and ethylenediamine (107153). In the oil series, 110 of 230 subjects showed a positive reaction 96 hours after application of the patch test. Benzisothiazolone (273132) gave the highest incidence of positive reactions, followed by triethanolamine (102716), hexahydrotriazine, alkanolamine vegetable fats, hexylene-glycol (107415), alkylbenzene-sulphonate (42615292), tricresyl-phosphate (1330785) and naphthenic oil. The authors conclude that a special test series of irritants should be used to test metallurgy workers.","Occupational Dermatoses From Cutting Oils Abs: Occupational dermatitis caused by various cutting oils was studied in 230 metallurgical workers. The subjects were surveyed by an extensive occupational and medical questionnaire. They were also given a series of patch tests to observe their responses to exposure to a standard series of oils and allergens. Paraphenylenediamine (106503) caused the highest percentage of positive responses, followed by potassium-dichromate (7778509), cobalt-chloride (1332827), thiuram (137268) mix, wood alcohols, formaldehyde (50000), neomycin (1404042), colophony (8050097), mercapto mix, and ethylenediamine (107153). In the oil series, 110 of 230 subjects showed a positive reaction 96 hours after application of the patch test. Benzisothiazolone (273132) gave the highest incidence of positive reactions, followed by triethanolamine (102716), hexahydrotriazine, alkanolamine vegetable fats, hexylene-glycol (107415), alkylbenzene-sulphonate (42615292), tricresyl-phosphate (1330785) and naphthenic oil. The authors conclude that a special test series of irritants should be used to test metallurgy workers."
1238098,Bedello et al. 1984,Contact Dermatitis Caused by Cobalt Naphthenate,"Two cases of contact allergies to cobalt-naphthenate (61789513) were described in workers in contact with rubber. A 41 year old nurse presented with facial dermatitis after wearing a black rubber mask during the sterilization of instruments with ethylene-oxide. Her dermatitis would improve when she was away from work and flare up again when she returned. The second patient was a 21 year old woman who was employed in the insertion of rubber windscreen wiper blades into the metal supports. She had dermatitis of the hands which disappeared after she changed jobs. Neither patient had dental bridge work or a history of sensitivity to metals. Patch tests with the standard rubber series, nickel-sulfate, and potassium-dichromate were negative. Patch tests were positive for cobalt-sulfate and cobalt-naphthenate at 2 percent concentration in petrolatum in both patients. Twenty comparisons tested negative to the two compounds at 48 and 72 hours. The authors state that these cases are apparently the first reported instances of sensitivity to cobalt-naphthenate in the rubber industry.","Contact Dermatitis Caused by Cobalt Naphthenate Abs: Two cases of contact allergies to cobalt-naphthenate (61789513) were described in workers in contact with rubber. A 41 year old nurse presented with facial dermatitis after wearing a black rubber mask during the sterilization of instruments with ethylene-oxide. Her dermatitis would improve when she was away from work and flare up again when she returned. The second patient was a 21 year old woman who was employed in the insertion of rubber windscreen wiper blades into the metal supports. She had dermatitis of the hands which disappeared after she changed jobs. Neither patient had dental bridge work or a history of sensitivity to metals. Patch tests with the standard rubber series, nickel-sulfate, and potassium-dichromate were negative. Patch tests were positive for cobalt-sulfate and cobalt-naphthenate at 2 percent concentration in petrolatum in both patients. Twenty comparisons tested negative to the two compounds at 48 and 72 hours. The authors state that these cases are apparently the first reported instances of sensitivity to cobalt-naphthenate in the rubber industry."
1238096,Corres 1984,"Contact Dermatitis from Frullania, Compositae and Other Plants","Cases of contact dermatitis from plants containing sesquiterpene lactones were presented. The 12 patients comprised a subgroup of 28 cases of plant related contact dermatitis observed over a 10 year period. Seven patients worked or had contact with woods and trees and exhibited Frullania sensitivity. Three individuals showed sensitivity to plants of the Compositae family, and one person was allergic to artichoke. A bricklayer showed sensitivity to potassium-chromate, thiuram mix, chlorpromazine, and helenin (546430). Patch tests were performed on these individuals using extracts from plants of the Frullanaceae, Magnoliaceae, Lauraceae, and Compositae families along with helenin. Common plants included in the testing were Frullania, magnolia, tulip-tree, laurel, yarrow, corn-chamomile, wild-chamomile, arnica, mugwort, chamomile, chrysanthemum, dahlia, sunflower, tansy, and feverfew. Patch tests to helenin were positive in all the Frullania sensitive patients as well as the bricklayer. Patch tests with feverfew extracts were positive in all persons exhibiting Frullania and Compositae sensitivity. Patch testing with Frullania extracts was negative in patients with Compositae sensitivity. Responses to arnica, laurel, sunflower, wild-chamomile, corn-chamomile, and tansy varied among individuals, with no distinguishing characteristics in either Frullania or Compositae sensitive groups. The author concludes that cross reactivities to plants occur primarily between those in the same family or those containing chemically related sesquiterpene lactones.","Contact Dermatitis from Frullania, Compositae and Other Plants Abs: Cases of contact dermatitis from plants containing sesquiterpene lactones were presented. The 12 patients comprised a subgroup of 28 cases of plant related contact dermatitis observed over a 10 year period. Seven patients worked or had contact with woods and trees and exhibited Frullania sensitivity. Three individuals showed sensitivity to plants of the Compositae family, and one person was allergic to artichoke. A bricklayer showed sensitivity to potassium-chromate, thiuram mix, chlorpromazine, and helenin (546430). Patch tests were performed on these individuals using extracts from plants of the Frullanaceae, Magnoliaceae, Lauraceae, and Compositae families along with helenin. Common plants included in the testing were Frullania, magnolia, tulip-tree, laurel, yarrow, corn-chamomile, wild-chamomile, arnica, mugwort, chamomile, chrysanthemum, dahlia, sunflower, tansy, and feverfew. Patch tests to helenin were positive in all the Frullania sensitive patients as well as the bricklayer. Patch tests with feverfew extracts were positive in all persons exhibiting Frullania and Compositae sensitivity. Patch testing with Frullania extracts was negative in patients with Compositae sensitivity. Responses to arnica, laurel, sunflower, wild-chamomile, corn-chamomile, and tansy varied among individuals, with no distinguishing characteristics in either Frullania or Compositae sensitive groups. The author concludes that cross reactivities to plants occur primarily between those in the same family or those containing chemically related sesquiterpene lactones."
1238095,Minni et al. 1984,A Study of the Chemical Structure of Particles in the Welding Fumes of Mild and Stainless Steel,"A study of the chemical surface structure of three types of welding fumes, manual metal arc welding of stainless steel (MMA), metal inert gas welding of stainless steel (MIG/SS), and manual metal arc welding of mild steel (MMA/MS), was conducted. Samples of airborne fumes from MMA/SS, MIG/SS, and MMA/MS welding were collected on membrane fibers. Analytical electron microscopy was used for bulk analysis of the fumes and for particle morphology studies. X-ray photoelectron spectroscopy (XPS) was used for semiquantitative surface analysis of the fumes and for detecting the oxidation states of the major metals. In addition, surface layers were removed from the particles by ion sputtering and changes in the oxidation states beneath the outermost surface layer were studied. MMA/SS welding fume iron (7439896) consisted mostly of trivalent iron as potassium-fluoroferrate (13815300). Chromium (7440473) existed as potassium-chromate (7789006). Manganese (7439965) occurred in the divalent and trivalent oxidation states, possibly as manganese-oxide (1317357). No major changes in the particles occurred during sputtering. MIG/SS welding fume contained mostly trivalent iron and chromium in iron and nickel (7440020) containing spinels. Manganese was found in the same form as in MMA/SS fume. Nickel was present in divalent and trivalent forms. Some of the particles contained a thin layer of silicon (7440213) containing material. MMA/MS fume particles contained iron as potassium-fluoroferrate on their surfaces and combined with manganese and oxygen deeper inside. The authors conclude that XPS combined with ion sputtering is a valuable tool for characterizing aerosols./BLOOD","A Study of the Chemical Structure of Particles in the Welding Fumes of Mild and Stainless Steel Abs: A study of the chemical surface structure of three types of welding fumes, manual metal arc welding of stainless steel (MMA), metal inert gas welding of stainless steel (MIG/SS), and manual metal arc welding of mild steel (MMA/MS), was conducted. Samples of airborne fumes from MMA/SS, MIG/SS, and MMA/MS welding were collected on membrane fibers. Analytical electron microscopy was used for bulk analysis of the fumes and for particle morphology studies. X-ray photoelectron spectroscopy (XPS) was used for semiquantitative surface analysis of the fumes and for detecting the oxidation states of the major metals. In addition, surface layers were removed from the particles by ion sputtering and changes in the oxidation states beneath the outermost surface layer were studied. MMA/SS welding fume iron (7439896) consisted mostly of trivalent iron as potassium-fluoroferrate (13815300). Chromium (7440473) existed as potassium-chromate (7789006). Manganese (7439965) occurred in the divalent and trivalent oxidation states, possibly as manganese-oxide (1317357). No major changes in the particles occurred during sputtering. MIG/SS welding fume contained mostly trivalent iron and chromium in iron and nickel (7440020) containing spinels. Manganese was found in the same form as in MMA/SS fume. Nickel was present in divalent and trivalent forms. Some of the particles contained a thin layer of silicon (7440213) containing material. MMA/MS fume particles contained iron as potassium-fluoroferrate on their surfaces and combined with manganese and oxygen deeper inside. The authors conclude that XPS combined with ion sputtering is a valuable tool for characterizing aerosols./BLOOD"
1238094,Pasricha and  Gupta 1983,Contact Dermatitis Due to Calcium Ammonium Nitrate,"A case of contact dermatitis due to calcium-ammonium-nitrate (15245122) (CAN) was reported. A farmer developed recurrent episodes of dermatitis on his hands and feet after sowing sorghum and using urea and CAN as fertilizers. In the winter, when his dermatitis was quiescent, patch tests were carried out with aqueous pastes of urea and CAN and leaves of Sorghum-vulgare, Pennisitum-typhoides, Parthenium-hysterophorus, Acacia-scorpiodes, and aqueous solutions of nickel-sulfate and potassium-dichromate. A positive reaction was seen only with CAN. A week later patch tests were repeated with CAN as a semisolid aqueous paste, a 10 percent aqueous solution, and 10 percent in petrolatum. A positive reaction was obtained only with CAN paste. Negative reactions with other allergens suggested that the skin was not in an irritable state. Thirteen comparison subjects did not react to CAN. Positive patch test response to CAN paste only indicated that the patient was not strongly hypersensitive. Negative patch tests with aqueous paste in comparison subjects indicated that CAN was not an irritant.","Contact Dermatitis Due to Calcium Ammonium Nitrate Abs: A case of contact dermatitis due to calcium-ammonium-nitrate (15245122) (CAN) was reported. A farmer developed recurrent episodes of dermatitis on his hands and feet after sowing sorghum and using urea and CAN as fertilizers. In the winter, when his dermatitis was quiescent, patch tests were carried out with aqueous pastes of urea and CAN and leaves of Sorghum-vulgare, Pennisitum-typhoides, Parthenium-hysterophorus, Acacia-scorpiodes, and aqueous solutions of nickel-sulfate and potassium-dichromate. A positive reaction was seen only with CAN. A week later patch tests were repeated with CAN as a semisolid aqueous paste, a 10 percent aqueous solution, and 10 percent in petrolatum. A positive reaction was obtained only with CAN paste. Negative reactions with other allergens suggested that the skin was not in an irritable state. Thirteen comparison subjects did not react to CAN. Positive patch test response to CAN paste only indicated that the patient was not strongly hypersensitive. Negative patch tests with aqueous paste in comparison subjects indicated that CAN was not an irritant."
1238091,Carson and  Smith 1983,Role Of Bentonite In Prevention Of T-2 Toxicosis In Rats,"The role of bentonite in the prevention of T-2 toxicosis was studied in rats. Male weanling rats were fed diets containing 5 percent bentonite, Zonolite-Verxite, or synthetic anion or cation exchange resins for 14 days with and without 3 micrograms per gram of crystalline T-2 toxin. Livers were assayed for nonspecific esterase activity. T-2 clearance was measured in rats dosed with tritiated T-2 toxin. Radioactivity in liver, kidney, small intestine, and muscle tissue was measured. T-2 toxin excretion following ingestion of 5.0, 7.5, or 10 percent bentonite was determined. Passage time to digestion was determined using the fecal marker chromium-sesquioxide. The feed consumption and body weight in controls given toxin only was reduced. Bentonite was the most effective treatment tested in minimizing the growth depression produced by T-2 toxin. Ten percent completely overcame toxicosis. Anion exchange resin had some effectiveness. Tritiated T-2 toxin produced radioactivity in feces and urine after 48 hours. The liver was the major site of radioactivity. Bentonite increased fecal excretion of toxin. Transit time of toxin through the gastrointestinal tract was reduced. The authors conclude that bentonite prevents T-2 toxicosis by nonspecific binding of the toxin in the gut. It should be tested in prevention and treatment for toxicosis in susceptible species of economic importance.","Role Of Bentonite In Prevention Of T-2 Toxicosis In Rats Abs: The role of bentonite in the prevention of T-2 toxicosis was studied in rats. Male weanling rats were fed diets containing 5 percent bentonite, Zonolite-Verxite, or synthetic anion or cation exchange resins for 14 days with and without 3 micrograms per gram of crystalline T-2 toxin. Livers were assayed for nonspecific esterase activity. T-2 clearance was measured in rats dosed with tritiated T-2 toxin. Radioactivity in liver, kidney, small intestine, and muscle tissue was measured. T-2 toxin excretion following ingestion of 5.0, 7.5, or 10 percent bentonite was determined. Passage time to digestion was determined using the fecal marker chromium-sesquioxide. The feed consumption and body weight in controls given toxin only was reduced. Bentonite was the most effective treatment tested in minimizing the growth depression produced by T-2 toxin. Ten percent completely overcame toxicosis. Anion exchange resin had some effectiveness. Tritiated T-2 toxin produced radioactivity in feces and urine after 48 hours. The liver was the major site of radioactivity. Bentonite increased fecal excretion of toxin. Transit time of toxin through the gastrointestinal tract was reduced. The authors conclude that bentonite prevents T-2 toxicosis by nonspecific binding of the toxin in the gut. It should be tested in prevention and treatment for toxicosis in susceptible species of economic importance."
1238090,Coenraads et al. 1984,Prevalence Of Eczema And Other Dermatoses Of The Hands And Forearms In Construction Workers In The Netherlands,"The prevalence of occupational dermatoses was epidemiologically investigated in workers in the Netherlands. A study sample was drawn from construction companies. Job categories were: carpenters; bricklayers and plasterers; technicians, plumbers, mechanics and reinforcers; administrators and supervisors; and unskilled workers. Hands and forearms of 1,691 workers were examined at work sites by a dermatologist. A person was registered as a case if he had skin disease at the time of examination or in the 3 years prior to examination. The cases were subjected to further questioning and patch testing. Control group consisted of 300 workers with no present or past history of dermatoses. A general population of 1,661 comparisons were also questioned and patch tested. The test materials for patch test, prepared in petrolatum, were: 0.5 percent potassium-dichromate (7778509), 1 percent cobalt-chloride, 1 percent thiruam mix, and 1 percent epoxy resins. Diagnoses of skin disorders as well asof eczema were subcategorized. In eczema cases, the condition was graded in terms of severity. About 7.8 percent workers had eczema and 1.8 percent had psoriasis. Among those with eczema, 4 percent had irritant dermatitis and 1.4 percent had allergic eczema. Prevalence percentages of mycoses, depigmentation, photodermatoses, urticaria and other dermatoses were 0.6, 0.4, 0.4, 0.2, and 0.3, respectively. Prevalence percentages of eczema in different job categories were: cement and plaster handlers 12.6; supervisors and administrators, 7.3; and technicians, 5.9. In other groups the prevalence varied between 6 and 9 percent. Supervisors and administrators had no cases with more than grade 3 eczema, but among technicians 28.5 percent had more than grade 3, and among plasterers 30 percent had grade 3 eczema. Positive patch tests were found in 15 percent of workers with eczema, 5.5 percent in controls, 6.1 percent in carpenters, 27.7 percent in bricklayers, and 7.6 percent in plasterers. In carpenters there was an association between eczema and exposure to solvents.","Prevalence Of Eczema And Other Dermatoses Of The Hands And Forearms In Construction Workers In The Netherlands Abs: The prevalence of occupational dermatoses was epidemiologically investigated in workers in the Netherlands. A study sample was drawn from construction companies. Job categories were: carpenters; bricklayers and plasterers; technicians, plumbers, mechanics and reinforcers; administrators and supervisors; and unskilled workers. Hands and forearms of 1,691 workers were examined at work sites by a dermatologist. A person was registered as a case if he had skin disease at the time of examination or in the 3 years prior to examination. The cases were subjected to further questioning and patch testing. Control group consisted of 300 workers with no present or past history of dermatoses. A general population of 1,661 comparisons were also questioned and patch tested. The test materials for patch test, prepared in petrolatum, were: 0.5 percent potassium-dichromate (7778509), 1 percent cobalt-chloride, 1 percent thiruam mix, and 1 percent epoxy resins. Diagnoses of skin disorders as well asof eczema were subcategorized. In eczema cases, the condition was graded in terms of severity. About 7.8 percent workers had eczema and 1.8 percent had psoriasis. Among those with eczema, 4 percent had irritant dermatitis and 1.4 percent had allergic eczema. Prevalence percentages of mycoses, depigmentation, photodermatoses, urticaria and other dermatoses were 0.6, 0.4, 0.4, 0.2, and 0.3, respectively. Prevalence percentages of eczema in different job categories were: cement and plaster handlers 12.6; supervisors and administrators, 7.3; and technicians, 5.9. In other groups the prevalence varied between 6 and 9 percent. Supervisors and administrators had no cases with more than grade 3 eczema, but among technicians 28.5 percent had more than grade 3, and among plasterers 30 percent had grade 3 eczema. Positive patch tests were found in 15 percent of workers with eczema, 5.5 percent in controls, 6.1 percent in carpenters, 27.7 percent in bricklayers, and 7.6 percent in plasterers. In carpenters there was an association between eczema and exposure to solvents."
1238085,Browne 1983,Painting And Varnishing,"Occupational safety and health hazards associated with painting and varnishing are reviewed. The methods of application of these finishes are described: by hand; dipping; roller, curtain, and flow coating; spray; airless spraying; electrostatic spray guns; and electrocoating. Hazards of high pressure with airless spraying and high voltage with electrostatic spraying and electrocoating are noted. Types of finishes available and their applications are described. Decorative paints, metal primers, emulsion paints, industrial finishes, car finishes, aircraft and marine finishes, wire enamels, and wood finishes are discussed. General hazards from such finish applications include fire, inhaling or imbibing of solvents, dermatitis, and lead poisoning. Along with lead, decorative paints may also contain aromatic benzene and phenyl mercuric fungicides. Hazards associated with industrial paints include aromatic benzene exposure, methylene-chloride inhalation, and dust exposure when rubbing down the finish paint. When working with car paints, the use of lead filler and molten lead for filling cracks and dents may give rise to dust. Sensitization dermatitis results from exposure to zinc-chromate primers. Lead pigments and refinishes containing isocyanates are discussed. Difficulty in providing adequate ventilation for large scale painting jobs associated with aircraft and marine craft is noted. Marine paints also include anti barnacle and herbicidal chemicals. Preventive measures are discussed in terms of responsibilities of management and painters. It is suggested that management should have sufficient knowledge of the hazards to train operatives, provide proper equipment, and supervise adequate hygiene. Painters should have knowledge of the material being used, use safety equipment, and ensure good housekeeping. The need for adequate ventilation and proper skin protection and cleaning is discussed.","Painting And Varnishing Abs: Occupational safety and health hazards associated with painting and varnishing are reviewed. The methods of application of these finishes are described: by hand; dipping; roller, curtain, and flow coating; spray; airless spraying; electrostatic spray guns; and electrocoating. Hazards of high pressure with airless spraying and high voltage with electrostatic spraying and electrocoating are noted. Types of finishes available and their applications are described. Decorative paints, metal primers, emulsion paints, industrial finishes, car finishes, aircraft and marine finishes, wire enamels, and wood finishes are discussed. General hazards from such finish applications include fire, inhaling or imbibing of solvents, dermatitis, and lead poisoning. Along with lead, decorative paints may also contain aromatic benzene and phenyl mercuric fungicides. Hazards associated with industrial paints include aromatic benzene exposure, methylene-chloride inhalation, and dust exposure when rubbing down the finish paint. When working with car paints, the use of lead filler and molten lead for filling cracks and dents may give rise to dust. Sensitization dermatitis results from exposure to zinc-chromate primers. Lead pigments and refinishes containing isocyanates are discussed. Difficulty in providing adequate ventilation for large scale painting jobs associated with aircraft and marine craft is noted. Marine paints also include anti barnacle and herbicidal chemicals. Preventive measures are discussed in terms of responsibilities of management and painters. It is suggested that management should have sufficient knowledge of the hazards to train operatives, provide proper equipment, and supervise adequate hygiene. Painters should have knowledge of the material being used, use safety equipment, and ensure good housekeeping. The need for adequate ventilation and proper skin protection and cleaning is discussed."
1238084,Cumpston 1983,"Zinc, Alloys And Compounds","The hazards of zinc (7440666) and its alloys and compounds are reviewed. Chemical and physical properties such as melting points, boiling points, molecular weights and specific gravities of zinc and zinc salts are listed. Zinc is widely distributed in nature. Zinc is used to protect ferrous metals, in zinc plates as anodes; zinc metal is diecast for components in industries such as the automobile industry. Zinc is an essential nutrient. Many zinc salts enter the body by inhalation, via skin, or by ingestion. Zinc salts are astringent, hygroscopic, corrosive, and antiseptic. They are irritants to the gastrointestinal tract, and emetic concentrations range from 657 to 2,280 parts per million. Zinc solubility in weakly acidic solutions has caused accidental poisoning when fruit drinks are prepared or stored in galvanized containers. The most frequent hazard is exposure to zinc-oxide (1314132) fume. Symptoms of metal fume fever include shivering, irregular fever, profuse sweating, nausea, thirst, headache, pains in the limbs, and exhaustion. Attacks are brief, and tolerance is acquired. Zinc-chloride (7646857) fume is an irritant to the eye and mucous membranes. Accidents with smoke generators have caused fatalities from bronchopneumonia and respiratory failure. Zinc-chromate (13530659) is suspected to be carcinogenic to humans. Zinc-cyanide (557211), zinc-sulfate (7733020), and zinc-phosphide (1314847) are used as pesticides, with additional uses in metal plating, skins and wood preservation, and rodenticides, respectively. Zinc-chloride and zinc-phosphide are the most dangerous and are responsible for the only cited deaths due to zinc poisoning. Zinc-chromate and zinc-chloride have been reported to result in ulceration of the skin. Zinc-oxide dust is the cause of sebaceous gland duct blockage and eczema. The risk of fire or explosion exists for powdered zinc and zinc compounds such as zinc/ammonium-nitrate. Prevention measures include exhaust ventilation, supplied air hood, protective clothing, eye and face protection, and respiration equipment. Fire explosion risk can be decreased by chemical storage in a cool, dry, well ventilated place away from ignition sources.","Zinc, Alloys And Compounds Abs: The hazards of zinc (7440666) and its alloys and compounds are reviewed. Chemical and physical properties such as melting points, boiling points, molecular weights and specific gravities of zinc and zinc salts are listed. Zinc is widely distributed in nature. Zinc is used to protect ferrous metals, in zinc plates as anodes; zinc metal is diecast for components in industries such as the automobile industry. Zinc is an essential nutrient. Many zinc salts enter the body by inhalation, via skin, or by ingestion. Zinc salts are astringent, hygroscopic, corrosive, and antiseptic. They are irritants to the gastrointestinal tract, and emetic concentrations range from 657 to 2,280 parts per million. Zinc solubility in weakly acidic solutions has caused accidental poisoning when fruit drinks are prepared or stored in galvanized containers. The most frequent hazard is exposure to zinc-oxide (1314132) fume. Symptoms of metal fume fever include shivering, irregular fever, profuse sweating, nausea, thirst, headache, pains in the limbs, and exhaustion. Attacks are brief, and tolerance is acquired. Zinc-chloride (7646857) fume is an irritant to the eye and mucous membranes. Accidents with smoke generators have caused fatalities from bronchopneumonia and respiratory failure. Zinc-chromate (13530659) is suspected to be carcinogenic to humans. Zinc-cyanide (557211), zinc-sulfate (7733020), and zinc-phosphide (1314847) are used as pesticides, with additional uses in metal plating, skins and wood preservation, and rodenticides, respectively. Zinc-chloride and zinc-phosphide are the most dangerous and are responsible for the only cited deaths due to zinc poisoning. Zinc-chromate and zinc-chloride have been reported to result in ulceration of the skin. Zinc-oxide dust is the cause of sebaceous gland duct blockage and eczema. The risk of fire or explosion exists for powdered zinc and zinc compounds such as zinc/ammonium-nitrate. Prevention measures include exhaust ventilation, supplied air hood, protective clothing, eye and face protection, and respiration equipment. Fire explosion risk can be decreased by chemical storage in a cool, dry, well ventilated place away from ignition sources."
1238083,Acheson 1983,"Nasal Cancer, Occupational","Occupational factors influencing the occurrence of nasal cancer are reviewed. The similarity of the nasal mucous membrane to the remainder of the respiratory system is described. The mechanism of action of dust particles is traced. The incidence of malignant disease of the nasal cavity and sinuses is rare in developed countries and among children. There is an increased incidence in developing countries such as Japan and Uganda where the incidence of nasal cancer is more than 2 times that of developed countries. The most common variety of tumor identified so far is the squamous cell epithelioma. Symptoms of nasal cancer are identified and include epistaxis, unilateral nasal obstruction, pain, swelling, and proptosis. Treatment by means of radical surgery and radiotherapy is mentioned. Occupational factors identified involve exposure to nickel (7440020) ore dust, zinc-potassium-chromate (37224570), calcium-chromate (13765190), mustard-gas (505602), isopropyl-alcohol (67630), and polycyclic aromatic hydrocarbons. Workers in the woodworking and footwear industries appear to be at high risk. Suggestive preventive measures involve minimization of exposure by altering or enclosing the industrial process, use of exhaust ventilation, and use of protective masks. The author suggests that studies of the chemistry and carcinogenicity of wood and leather dust may provide needed epidemiological information.","Nasal Cancer, Occupational Abs: Occupational factors influencing the occurrence of nasal cancer are reviewed. The similarity of the nasal mucous membrane to the remainder of the respiratory system is described. The mechanism of action of dust particles is traced. The incidence of malignant disease of the nasal cavity and sinuses is rare in developed countries and among children. There is an increased incidence in developing countries such as Japan and Uganda where the incidence of nasal cancer is more than 2 times that of developed countries. The most common variety of tumor identified so far is the squamous cell epithelioma. Symptoms of nasal cancer are identified and include epistaxis, unilateral nasal obstruction, pain, swelling, and proptosis. Treatment by means of radical surgery and radiotherapy is mentioned. Occupational factors identified involve exposure to nickel (7440020) ore dust, zinc-potassium-chromate (37224570), calcium-chromate (13765190), mustard-gas (505602), isopropyl-alcohol (67630), and polycyclic aromatic hydrocarbons. Workers in the woodworking and footwear industries appear to be at high risk. Suggestive preventive measures involve minimization of exposure by altering or enclosing the industrial process, use of exhaust ventilation, and use of protective masks. The author suggests that studies of the chemistry and carcinogenicity of wood and leather dust may provide needed epidemiological information."
1238082,Zielhuis 1983,"Lead, Alloys And Inorganic Compounds","Hazards and toxicity assessment associated with lead (7439921), various lead alloys, and inorganic lead compounds are reviewed. Metals such as antimony (7440360), tin (7440315), and bismuth (7440699) may be added to lead to improve its mechanical or chemical properties. Lead may be added to alloys such as brass, bronze, and steel. Common inorganic lead compounds include lead-monoxide (1317368), lead-dioxide (1309600), lead-tetroxide (1314416), lead-sesquioxide (1314278), lead-carbonate (598630), lead-sulfate (7446142), lead-chromate (7758976), lead-arsenate (3687318), lead-chloride (7758954), lead-silicate (11120222), and lead-azide (13424469). Adverse neurophysiological effects on the nervous system, resulting in minor brain dysfunction and in impaired motor conduction velocity in peripheral nerves, occur at exposure concentrations once regarded as acceptable. Potential adverse effects on the offspring of pregnant workers has resulted in separate recommendations for female workers of fertile age. Inorganic lead compounds enter into the body primarily by inhalation and ingestion. The main route of entry for workers is the respiratory tract. A certain amount may be absorbed into the air passages, but the main amount is taken up to the pulmonary blood stream, of which 90 percent will be held by the erythrocytes. Lead also accumulates in bone tissue. In nonoccupationally exposed adults, individual lead concentrations usually do not exceed 25 to 30 micrograms per 100 milliliters (microg/ml) and are normally 15 to 25 microg/100ml. The author concludes that workers should undergo periodic medical examinations to assess lead concentrations. The primary yardstick for assessing overexposure is lead concentration in the blood.","Lead, Alloys And Inorganic Compounds Abs: Hazards and toxicity assessment associated with lead (7439921), various lead alloys, and inorganic lead compounds are reviewed. Metals such as antimony (7440360), tin (7440315), and bismuth (7440699) may be added to lead to improve its mechanical or chemical properties. Lead may be added to alloys such as brass, bronze, and steel. Common inorganic lead compounds include lead-monoxide (1317368), lead-dioxide (1309600), lead-tetroxide (1314416), lead-sesquioxide (1314278), lead-carbonate (598630), lead-sulfate (7446142), lead-chromate (7758976), lead-arsenate (3687318), lead-chloride (7758954), lead-silicate (11120222), and lead-azide (13424469). Adverse neurophysiological effects on the nervous system, resulting in minor brain dysfunction and in impaired motor conduction velocity in peripheral nerves, occur at exposure concentrations once regarded as acceptable. Potential adverse effects on the offspring of pregnant workers has resulted in separate recommendations for female workers of fertile age. Inorganic lead compounds enter into the body primarily by inhalation and ingestion. The main route of entry for workers is the respiratory tract. A certain amount may be absorbed into the air passages, but the main amount is taken up to the pulmonary blood stream, of which 90 percent will be held by the erythrocytes. Lead also accumulates in bone tissue. In nonoccupationally exposed adults, individual lead concentrations usually do not exceed 25 to 30 micrograms per 100 milliliters (microg/ml) and are normally 15 to 25 microg/100ml. The author concludes that workers should undergo periodic medical examinations to assess lead concentrations. The primary yardstick for assessing overexposure is lead concentration in the blood."
1238080,Sato et al. 1983,Study on the actions of nephrotoxic chemicals using kidney-derived cells,"The effects of nephrotoxic chemicals on enzyme release were studied in cultured kidney cells. Their effects on short circuit current of epithelial monolayers were studied in cells grown on Millipore filters. Established cell lines LLC-PK1 from pig, JTC-12 from monkey, MDCK from dog, and G-3 from rabbit were cultured and exposed to 0.0000001 to 0.0001 molar (M) concentrations of gentamicin (1403663), cadmium-chloride (10108642), sodium-chromate (7775099), or folic-acid (59303) for 24 hours. Alkaline-phosphatase, gamma-glutamyl-transferase and lactate-dehydrogenase activities were determined by standard methods and compared to those of control untreated cells. Exponentially growing MDCK cells were plated on Millipore filters mounted between two chambers. The electrical potential difference between two chambers was measured and short circuit current was measured as current required to clamp the potential difference to 0 milliVolts on both sides of the filter. The release of lactate-dehydrogenase from LLC-PK1 and JTC-12 cells was increased at high concentrations of folic-acid. At very low concentrations release was elevated from MDCK cells as it was again at very high concentrations. Release of alkaline-phosphatase and gamma-glutamyl-transferase from LLC-PK1 and JTC-12 cells was not affected at any concentration. Folic-acid increased release of alkaline-phosphatase. At 0.000001M sodium-chromate, lactate-dehydrogenase was released at increased amounts from JTC-12 cells alone. At 0.0000001 to 0.00001M, sodium-chromate caused decreased release of alkaline-phosphatase and gamma-glutamyl-transferase from LLC-PK1 cells and MDCK cells. Gentamicin caused increased release of alkaline-phosphatase from LLC-PK1 cells, gamma-glutamyl-transferase from MDCK cells and lactate-dehydrogenase from G-3 cells and reduced release of gamma-glutamyl-transferase from LLC-PK1 cells. Cadmium-chloride did not affect release of JTC-12 cells but did increase release of gamma-glutamyl-transferase from LLC-PK1 and MDCK cells. Short circuit current was significantly and irreversibly decreased by folic-acid. The authors conclude that cultured kidney cells reveal the nephrotoxic effects of chemicals.","Study on the actions of nephrotoxic chemicals using kidney-derived cells Abs: The effects of nephrotoxic chemicals on enzyme release were studied in cultured kidney cells. Their effects on short circuit current of epithelial monolayers were studied in cells grown on Millipore filters. Established cell lines LLC-PK1 from pig, JTC-12 from monkey, MDCK from dog, and G-3 from rabbit were cultured and exposed to 0.0000001 to 0.0001 molar (M) concentrations of gentamicin (1403663), cadmium-chloride (10108642), sodium-chromate (7775099), or folic-acid (59303) for 24 hours. Alkaline-phosphatase, gamma-glutamyl-transferase and lactate-dehydrogenase activities were determined by standard methods and compared to those of control untreated cells. Exponentially growing MDCK cells were plated on Millipore filters mounted between two chambers. The electrical potential difference between two chambers was measured and short circuit current was measured as current required to clamp the potential difference to 0 milliVolts on both sides of the filter. The release of lactate-dehydrogenase from LLC-PK1 and JTC-12 cells was increased at high concentrations of folic-acid. At very low concentrations release was elevated from MDCK cells as it was again at very high concentrations. Release of alkaline-phosphatase and gamma-glutamyl-transferase from LLC-PK1 and JTC-12 cells was not affected at any concentration. Folic-acid increased release of alkaline-phosphatase. At 0.000001M sodium-chromate, lactate-dehydrogenase was released at increased amounts from JTC-12 cells alone. At 0.0000001 to 0.00001M, sodium-chromate caused decreased release of alkaline-phosphatase and gamma-glutamyl-transferase from LLC-PK1 cells and MDCK cells. Gentamicin caused increased release of alkaline-phosphatase from LLC-PK1 cells, gamma-glutamyl-transferase from MDCK cells and lactate-dehydrogenase from G-3 cells and reduced release of gamma-glutamyl-transferase from LLC-PK1 cells. Cadmium-chloride did not affect release of JTC-12 cells but did increase release of gamma-glutamyl-transferase from LLC-PK1 and MDCK cells. Short circuit current was significantly and irreversibly decreased by folic-acid. The authors conclude that cultured kidney cells reveal the nephrotoxic effects of chemicals."
1238079,White et al. 1983,Allergic Contact Dermatitis From An Organic Di-isocyante,"Cases of allergic contact dermatitis resulting from exposure to an organic diisocyanate were described. Seven females employed in a factory which made car badges that used dicyclohexylmethane-4,4'-diisocyanate (DMDI) as one of the components of a polyurethane resin used in coating the badges developed rashes on their arms and faces. In six of the subjects, the rash was an itchy, erythematous eruption. The seventh subject experienced dry facial skin. Four of the subjects had a history of nickel allergy due to previous contact with jewelry. Patch testing was performed with polyester polyols, DMDI, potassium-dichromate (7778509), thiuram (137268) mix, and nickel-sulfate (7786814). Two of the subjects gave a positive response to DMDI. All four subjects with a history of nickel allergy gave a positive response to nickel-sulfate. No occupational source of nickel was found in the facility that might be responsible for the rashes. The authors conclude that two of the subjects are clearly allergic to DMDI. DMDI should be handled with caution, as skin allergy attributed to it has been reported from several other sources.","Allergic Contact Dermatitis From An Organic Di-isocyante Abs: Cases of allergic contact dermatitis resulting from exposure to an organic diisocyanate were described. Seven females employed in a factory which made car badges that used dicyclohexylmethane-4,4'-diisocyanate (DMDI) as one of the components of a polyurethane resin used in coating the badges developed rashes on their arms and faces. In six of the subjects, the rash was an itchy, erythematous eruption. The seventh subject experienced dry facial skin. Four of the subjects had a history of nickel allergy due to previous contact with jewelry. Patch testing was performed with polyester polyols, DMDI, potassium-dichromate (7778509), thiuram (137268) mix, and nickel-sulfate (7786814). Two of the subjects gave a positive response to DMDI. All four subjects with a history of nickel allergy gave a positive response to nickel-sulfate. No occupational source of nickel was found in the facility that might be responsible for the rashes. The authors conclude that two of the subjects are clearly allergic to DMDI. DMDI should be handled with caution, as skin allergy attributed to it has been reported from several other sources."
1238075,Martin et al. 1984,The Comparative Toxicity Of Volcanic Ash And Quartz. Effects On Cells Derived From The Human Lung,"The cytotoxicity of volcanic ash and free crystalline silica (7631869) was assessed in human alveolar macrophages and A549 carcinoma cells resembling human type II pneumocytes. Alveolar macrophages from healthy nonsmokers were incubated for up to 24 hours, alone or with 1.0 milligram per milliliter (mg/ml) respirable volcanic ash or quartz. At intervals to 24 hours, cytotoxicity was assessed by trypan-blue exclusion and lactate-dehydrogenase release, and neutrophil chemotactic activity was measured in culture supernatants. A549 chemotactic activity was measured in culture supernatants. A549 cell monolayers were incubated overnight with 0.1 to 10.0mg/ml volcanic ash or quartz (14808607) on medium containing labeled sodium-chromate. Some cultures also contained albumin, IgG, or secretory IgA. After incubation, cell lysis was assessed by the release of radioactive label. As measured by trypan-blue exclusion, the viability of alveolar macrophages incubated with volcanic ash was about 90 percent after 6 hours and 78 percent after 24 hours, not significantly different from control values. The viability of quartz treated cultures was about 75 percent after 6 hours and 60 percent after 24 hours. Lactate-dehydrogenase release was about double control after 4 hours of quartz exposure, and was increased about 60 and 120 percent by 24 hours exposure to volcanic ash and quartz, respectively. From 2 hours on, chemotactic activity in supernatants of quartz treated cultures was 2.5 to 3 times control values; volcanic ash values did not differ significantly from controls. Cell lysis of A549 cells was about 50 and 75 percent in cultures treated with 0.5 and 10mg/ml quartz, respectively, and 25 and 35 percent in cultures treated with 5 and 10mg/ml volcanic ash. Quartz cytotoxicity was reduced 18 percent to 29 percent by 0.2mg/ml protein and over 50 percent by 1.0mg/ml protein.","The Comparative Toxicity Of Volcanic Ash And Quartz. Effects On Cells Derived From The Human Lung Abs: The cytotoxicity of volcanic ash and free crystalline silica (7631869) was assessed in human alveolar macrophages and A549 carcinoma cells resembling human type II pneumocytes. Alveolar macrophages from healthy nonsmokers were incubated for up to 24 hours, alone or with 1.0 milligram per milliliter (mg/ml) respirable volcanic ash or quartz. At intervals to 24 hours, cytotoxicity was assessed by trypan-blue exclusion and lactate-dehydrogenase release, and neutrophil chemotactic activity was measured in culture supernatants. A549 chemotactic activity was measured in culture supernatants. A549 cell monolayers were incubated overnight with 0.1 to 10.0mg/ml volcanic ash or quartz (14808607) on medium containing labeled sodium-chromate. Some cultures also contained albumin, IgG, or secretory IgA. After incubation, cell lysis was assessed by the release of radioactive label. As measured by trypan-blue exclusion, the viability of alveolar macrophages incubated with volcanic ash was about 90 percent after 6 hours and 78 percent after 24 hours, not significantly different from control values. The viability of quartz treated cultures was about 75 percent after 6 hours and 60 percent after 24 hours. Lactate-dehydrogenase release was about double control after 4 hours of quartz exposure, and was increased about 60 and 120 percent by 24 hours exposure to volcanic ash and quartz, respectively. From 2 hours on, chemotactic activity in supernatants of quartz treated cultures was 2.5 to 3 times control values; volcanic ash values did not differ significantly from controls. Cell lysis of A549 cells was about 50 and 75 percent in cultures treated with 0.5 and 10mg/ml quartz, respectively, and 25 and 35 percent in cultures treated with 5 and 10mg/ml volcanic ash. Quartz cytotoxicity was reduced 18 percent to 29 percent by 0.2mg/ml protein and over 50 percent by 1.0mg/ml protein."
1238066,Uyeki and  Nishio 1983,Antiproliferative and genotoxic effects Of chromium on cultured mammalian cells,"The cytotoxic and genotoxic effects of chromium (7440473) on mammalian cell cultures were investigated. Chinese-hamster ovary (CHO) cells were grown in tissue cultures. Potassium-dichromate (7778509), a hexavalent form, and chromic-chloride (10025737), a trivalent form, were added at 0.1, 1.0, and 10 micromoles (micromol) to CHO cell cultures. Proliferation of CHO cells was monitored. Ascorbic-acid (50817) at 50 micrograms per milliliter (microg/ml) was added for periods up to 6 hours to cultures treated with hexavalent chromium. Several sulfhydryl containing compounds were added to cultures treated with hexavalent compounds under similar conditions. Sister chromatid exchanges (SCEs) induced in cultured CHO cells were counted as a measure of genotoxicity after exposure to 0.01, 0.03, 0.1, 0.3, and 1.0micromol trivalent chromium. Ascorbic-acid was added at 50microg/ml up to 4 hours after similar cultures received hexavalent chromium. All results were compared with those from control cultures. Trivalent chromium at concentrations up to 10micromol did not significantly alter proliferation of CHO cells. At 0.1micromol, hexavalent chromium did not reduce proliferation of CHO cells, but at higher concentrations proliferation was reduced. Addition of ascorbic-acid reversed these anti proliferative effects, but the sulfhydryl containing compounds did not. Trivalent chromium at up to 10micromol did not induce SCEs. Hexavalent chromium induced 114 percent of control SCEs at 1.0micromol. Ascorbic-acid reversed SCE induction. The authors conclude that the genotoxic response demonstrated may have a causal relationship to the inhibition of proliferation observed.","Antiproliferative and genotoxic effects Of chromium on cultured mammalian cells Abs: The cytotoxic and genotoxic effects of chromium (7440473) on mammalian cell cultures were investigated. Chinese-hamster ovary (CHO) cells were grown in tissue cultures. Potassium-dichromate (7778509), a hexavalent form, and chromic-chloride (10025737), a trivalent form, were added at 0.1, 1.0, and 10 micromoles (micromol) to CHO cell cultures. Proliferation of CHO cells was monitored. Ascorbic-acid (50817) at 50 micrograms per milliliter (microg/ml) was added for periods up to 6 hours to cultures treated with hexavalent chromium. Several sulfhydryl containing compounds were added to cultures treated with hexavalent compounds under similar conditions. Sister chromatid exchanges (SCEs) induced in cultured CHO cells were counted as a measure of genotoxicity after exposure to 0.01, 0.03, 0.1, 0.3, and 1.0micromol trivalent chromium. Ascorbic-acid was added at 50microg/ml up to 4 hours after similar cultures received hexavalent chromium. All results were compared with those from control cultures. Trivalent chromium at concentrations up to 10micromol did not significantly alter proliferation of CHO cells. At 0.1micromol, hexavalent chromium did not reduce proliferation of CHO cells, but at higher concentrations proliferation was reduced. Addition of ascorbic-acid reversed these anti proliferative effects, but the sulfhydryl containing compounds did not. Trivalent chromium at up to 10micromol did not induce SCEs. Hexavalent chromium induced 114 percent of control SCEs at 1.0micromol. Ascorbic-acid reversed SCE induction. The authors conclude that the genotoxic response demonstrated may have a causal relationship to the inhibition of proliferation observed."
1238063,Taddia and  Lanza 1984,Determination Of Chromium In Gallium Arsenide By Electrothermal Atomic Absorption Spectrometry,"Use of the furnace atomic absorption spectrometry (AAS) method for determination of traces of chromium (7440473) was assessed in gallium-arsenide (1303000). An atomic absorption spectrometer equipped with a graphite furnace was employed for the determination of chromium. Uncoated and pyrolytically coated graphite tubes were compared. Stock solutions were prepared from potassium-chromate (7789006) and chromium-trichloride (10025737). Dilute aqua regia was prepared. Two milliliters (ml) of aqua regia were added to 25 to 100 milligrams of finely powdered gallium-arsenide. The solution was warmed; dissolution was completed at room temperature. Chromium was determined using standard addition techniques. Three replicate 10 microliter (microl) portions of the sample solution were atomized. The procedure was repeated after adding 20, 40, and 60microl of 10 microgram chromium(VI) (18540299) solution. A blank determination was made under identical conditions. Chromium(III) (16065831) and chromium(IV) (15723281) were examined. Chromium in either oxidation state at the 30 nanogram/ml concentration was not lost until 1100 to 1200 degrees-C. Sensitivity obtained by using pyrolytically coated graphite tubes was 2.3 times greater than for uncoated tubes. The authors conclude that graphite furnace AAS is useful for chromium determination in chromium doped gallium-arsenide.","Determination Of Chromium In Gallium Arsenide By Electrothermal Atomic Absorption Spectrometry Abs: Use of the furnace atomic absorption spectrometry (AAS) method for determination of traces of chromium (7440473) was assessed in gallium-arsenide (1303000). An atomic absorption spectrometer equipped with a graphite furnace was employed for the determination of chromium. Uncoated and pyrolytically coated graphite tubes were compared. Stock solutions were prepared from potassium-chromate (7789006) and chromium-trichloride (10025737). Dilute aqua regia was prepared. Two milliliters (ml) of aqua regia were added to 25 to 100 milligrams of finely powdered gallium-arsenide. The solution was warmed; dissolution was completed at room temperature. Chromium was determined using standard addition techniques. Three replicate 10 microliter (microl) portions of the sample solution were atomized. The procedure was repeated after adding 20, 40, and 60microl of 10 microgram chromium(VI) (18540299) solution. A blank determination was made under identical conditions. Chromium(III) (16065831) and chromium(IV) (15723281) were examined. Chromium in either oxidation state at the 30 nanogram/ml concentration was not lost until 1100 to 1200 degrees-C. Sensitivity obtained by using pyrolytically coated graphite tubes was 2.3 times greater than for uncoated tubes. The authors conclude that graphite furnace AAS is useful for chromium determination in chromium doped gallium-arsenide."
1238062,Walsh and  Ryden 1984,The Effect Of Chronic Ingestion Of Lead On Gastrointestinal Transit In Rats,"The effects of chronic lead (7439921) exposure on gastrointestinal transit in rats were investigated. Male Wistar-rats ingested pulverized lead-acetate (301042) in their feed, receiving 1, 2, or 4 percent lead-acetate. Control animals received the same diet without lead. Fecal weight and water content were followed. Gamma-aminolevulinic-acid in 24 hour urine was measured on days 46 and 47. After 7 and 8 weeks of treatment, radiolabeled sodium-chromate (7775113) was administered by gastric intubation to animals receiving 2 or 4 percent lead-acetate. Animals were then given control or lead containing diet 1, 10, or 22 hours later, and radiation in feces and urine was determined every 3 hours for 48 hours. At 8 weeks, animals were killed and blood lead concentrations and kidney weights were measured. Throughout the experiment food consumption was reduced in experimental animals; by week 8, experimental animal weights averaged 82 percent of controls. However, fecal weight in relation to food intake and percentage water content of feces were not affected by lead treatment. Twenty four hour gamma-aminolevulinic-acid excretion was increased 10 times in lead treated animals, from 50.7 to 527.5 micrograms (microg). Mean gastric content of radiolabeled chromium was not significantly affected by lead treatment, although there was a trend toward slower transit through the stomach and small intestine in lead treated animals. Fecal excretion of chromium (7440473) was also not significantly affected by lead ingestion. Blood lead values were 196, 140, and 247microg per deciliter in animals on the 1, 2, and 4 percent diets, respectively. Hematocrits were reduced approximately four units by each lead regimen. Dose dependent increases in kidney water content increased 2 to 3 percent in all groups. The authors conclude that dietary lead does not significantly affect gastrointestinal transit even at concentrations that result in markedly elevated blood lead concentrations and clear evidence of systemic toxicity.","The Effect Of Chronic Ingestion Of Lead On Gastrointestinal Transit In Rats Abs: The effects of chronic lead (7439921) exposure on gastrointestinal transit in rats were investigated. Male Wistar-rats ingested pulverized lead-acetate (301042) in their feed, receiving 1, 2, or 4 percent lead-acetate. Control animals received the same diet without lead. Fecal weight and water content were followed. Gamma-aminolevulinic-acid in 24 hour urine was measured on days 46 and 47. After 7 and 8 weeks of treatment, radiolabeled sodium-chromate (7775113) was administered by gastric intubation to animals receiving 2 or 4 percent lead-acetate. Animals were then given control or lead containing diet 1, 10, or 22 hours later, and radiation in feces and urine was determined every 3 hours for 48 hours. At 8 weeks, animals were killed and blood lead concentrations and kidney weights were measured. Throughout the experiment food consumption was reduced in experimental animals; by week 8, experimental animal weights averaged 82 percent of controls. However, fecal weight in relation to food intake and percentage water content of feces were not affected by lead treatment. Twenty four hour gamma-aminolevulinic-acid excretion was increased 10 times in lead treated animals, from 50.7 to 527.5 micrograms (microg). Mean gastric content of radiolabeled chromium was not significantly affected by lead treatment, although there was a trend toward slower transit through the stomach and small intestine in lead treated animals. Fecal excretion of chromium (7440473) was also not significantly affected by lead ingestion. Blood lead values were 196, 140, and 247microg per deciliter in animals on the 1, 2, and 4 percent diets, respectively. Hematocrits were reduced approximately four units by each lead regimen. Dose dependent increases in kidney water content increased 2 to 3 percent in all groups. The authors conclude that dietary lead does not significantly affect gastrointestinal transit even at concentrations that result in markedly elevated blood lead concentrations and clear evidence of systemic toxicity."
1238059,Osaki et al. 1983,Gel Chromatographic Behaviour Of Trace Amounts Of Chromium(VI) And Hydrolysed Chromium(III) In Aqueous Solution,"The gel chromatographic behavior of trace amounts of chromate (11104599) and hydrolyzed chromium(III) (16065831) species in aqueous solutions was investigated. Sample solutions with 0.00000002 molar chromium(III) concentrations, radiolabeled by adding chromium-51 (14392020) as sodium-chromate, (7775113) were prepared. A glass column, 450 by 19 millimeters, was packed with a slurry of Sephadex G-50 dry gel which was swelled in distilled water for 24 hours. Radioactivity in 5 milliliter aliquots of the sample solutions was counted using liquid scintillation counting. Aliquots were stored in polyethylene bottles for 1 and 7 days before chromatographic analysis or analyzed immediately. The effects of pH shifts from 1.42 to 12.63 on hydrolyzed chromium(III) solutions were also examined. A sharp peak assigned to chromate ions was obtained from gel chromatography of chromium(VI) (18540299) in 0.01 or 0.05 molar (M) concentrations of sodium-chloride (pH 7). The peak for chromium(VI) in 0.005M concentrations of sodium-chloride was slightly shifted and that for chromium(VI) in distilled water was further shifted, possibly due to the ion exchange effect of the gel. At pH 1.42, 100 percent of chromium(III) eluted in the fraction of lower molecular weight (fraction 1). Up to pH 7.75 this fraction decreased, while the eluted fraction of higher molecular weight (fraction 2) increased as did the quantity of chromium(III) adsorbed on to the gel (fraction 3). Chromium(III) was also partially adsorbed on to the polyethylene bottle during storage (fraction 4). The peaks of fraction 1 were eluted in the same fraction number to the chromate ions. The peaks of fraction 2 were eluted at the void volume of the column. The authors conclude that the chromium(III) species in the samples may consist of aqueous ions, or the latent hydroxide. The chromium concentrations of fractions 1, 2, and 3 correlate with neither the pH of the sample solutions nor the storage times.","Gel Chromatographic Behaviour Of Trace Amounts Of Chromium(VI) And Hydrolysed Chromium(III) In Aqueous Solution Abs: The gel chromatographic behavior of trace amounts of chromate (11104599) and hydrolyzed chromium(III) (16065831) species in aqueous solutions was investigated. Sample solutions with 0.00000002 molar chromium(III) concentrations, radiolabeled by adding chromium-51 (14392020) as sodium-chromate, (7775113) were prepared. A glass column, 450 by 19 millimeters, was packed with a slurry of Sephadex G-50 dry gel which was swelled in distilled water for 24 hours. Radioactivity in 5 milliliter aliquots of the sample solutions was counted using liquid scintillation counting. Aliquots were stored in polyethylene bottles for 1 and 7 days before chromatographic analysis or analyzed immediately. The effects of pH shifts from 1.42 to 12.63 on hydrolyzed chromium(III) solutions were also examined. A sharp peak assigned to chromate ions was obtained from gel chromatography of chromium(VI) (18540299) in 0.01 or 0.05 molar (M) concentrations of sodium-chloride (pH 7). The peak for chromium(VI) in 0.005M concentrations of sodium-chloride was slightly shifted and that for chromium(VI) in distilled water was further shifted, possibly due to the ion exchange effect of the gel. At pH 1.42, 100 percent of chromium(III) eluted in the fraction of lower molecular weight (fraction 1). Up to pH 7.75 this fraction decreased, while the eluted fraction of higher molecular weight (fraction 2) increased as did the quantity of chromium(III) adsorbed on to the gel (fraction 3). Chromium(III) was also partially adsorbed on to the polyethylene bottle during storage (fraction 4). The peaks of fraction 1 were eluted in the same fraction number to the chromate ions. The peaks of fraction 2 were eluted at the void volume of the column. The authors conclude that the chromium(III) species in the samples may consist of aqueous ions, or the latent hydroxide. The chromium concentrations of fractions 1, 2, and 3 correlate with neither the pH of the sample solutions nor the storage times."
1238053,Hellquist et al. 1983,Nasal Symptoms And Histopathology In A Group Of Spray-Painters,"Alterations of the nasal mucosa and adherent clinical symptoms were studied in ten male spray painters. The spray painters worked at a factory that manufactured open fire places and spray painted primers and finishing coat. Personal breathing zone samples were analyzed for solvents and dust. Exposure history, symptoms of the respiratory tract, and smoking habits were recorded. The nose was examined clinically and histologically. Forced expiratory volume in 1 second (FEV) and vital capacity were determined. Air samples were shown to contain 13 solvents. Toluene (108883) and isobutyl-acetate (110190) were most abundant, ranging in concentration from 3 to 18 and 2 to 44 milligrams per cubic meter, respectively. Airborne dust was composed mostly of chromium-oxide (11118573) and zinc-oxide (1314132), concentrations being below what are considered toxic limit values. Seven of the ten workers were smokers. Three (two that did not smoke) had histories of nasal symptoms. All ten had grossly normal nasal mucosa. FEV and vital capacity ranged from 71 to 130 and 64 to 121 percent of predicted values, respectively. In all cases the nasal mucosa was lined with a squamous epithelium. Two cases showed mild epithelial dysplasia. Epithelial budding was present in five cases. The authors believe that early presymptomatic detection of nasal mucosal disturbances may be possible.","Nasal Symptoms And Histopathology In A Group Of Spray-Painters Abs: Alterations of the nasal mucosa and adherent clinical symptoms were studied in ten male spray painters. The spray painters worked at a factory that manufactured open fire places and spray painted primers and finishing coat. Personal breathing zone samples were analyzed for solvents and dust. Exposure history, symptoms of the respiratory tract, and smoking habits were recorded. The nose was examined clinically and histologically. Forced expiratory volume in 1 second (FEV) and vital capacity were determined. Air samples were shown to contain 13 solvents. Toluene (108883) and isobutyl-acetate (110190) were most abundant, ranging in concentration from 3 to 18 and 2 to 44 milligrams per cubic meter, respectively. Airborne dust was composed mostly of chromium-oxide (11118573) and zinc-oxide (1314132), concentrations being below what are considered toxic limit values. Seven of the ten workers were smokers. Three (two that did not smoke) had histories of nasal symptoms. All ten had grossly normal nasal mucosa. FEV and vital capacity ranged from 71 to 130 and 64 to 121 percent of predicted values, respectively. In all cases the nasal mucosa was lined with a squamous epithelium. Two cases showed mild epithelial dysplasia. Epithelial budding was present in five cases. The authors believe that early presymptomatic detection of nasal mucosal disturbances may be possible."
1238052,Rogers et al. 1983,Augmentation Of Murine Natural Killer Cell Activity By Manganese Chloride,"The influence of manganese (7439965) (Mn) on the activity of natural killer cells was investigated in mice. Male CBA-mice and A/J-mice and female C57Bl/6J-mice were given a single intramuscular injection of 40 or 80 micrograms per gram (microg/g) manganese-chloride (7773015) (MnCl2) 1 day before evaluation of natural killer cell activity. In another test, interferon inducers were injected intravenously 18 to 24 hours before testing. Some control and C57Bl/6J-mice were injected with rabbit anti mouse interferon at doses of 1000 or 500 neutralizing units before and after MnCl2 treatment. The natural killer cell assay was performed 24 hours after metal treatment. Mice were sacrificed and spleens were removed. Tumor cells were maintained and used as target cells. Target cells were labeled with sodium-chromate and cell activity was examined in-vitro and in-vivo. Natural killer cell activity was sustained at high concentrations for at least 3 days after 80microg/g Mn treatment. MnCl2 also enhanced cytoxicity of spleen cells. The percent cytoxicity ranged from 19.4 to 47.8 in MnCl2 treated cells against target cells. This compared with 6.5 to 28.6 percent cytotoxicity in the control group. Interferon titers for MnCl2, and the two interferon inducer treated mice were 76, 162, and 290, respectively. This compared with an interferon titer of 23 for the control group. The authors conclude that Mn is capable of enhancing murine natural killer cell activity against certain tumor cells.","Augmentation Of Murine Natural Killer Cell Activity By Manganese Chloride Abs: The influence of manganese (7439965) (Mn) on the activity of natural killer cells was investigated in mice. Male CBA-mice and A/J-mice and female C57Bl/6J-mice were given a single intramuscular injection of 40 or 80 micrograms per gram (microg/g) manganese-chloride (7773015) (MnCl2) 1 day before evaluation of natural killer cell activity. In another test, interferon inducers were injected intravenously 18 to 24 hours before testing. Some control and C57Bl/6J-mice were injected with rabbit anti mouse interferon at doses of 1000 or 500 neutralizing units before and after MnCl2 treatment. The natural killer cell assay was performed 24 hours after metal treatment. Mice were sacrificed and spleens were removed. Tumor cells were maintained and used as target cells. Target cells were labeled with sodium-chromate and cell activity was examined in-vitro and in-vivo. Natural killer cell activity was sustained at high concentrations for at least 3 days after 80microg/g Mn treatment. MnCl2 also enhanced cytoxicity of spleen cells. The percent cytoxicity ranged from 19.4 to 47.8 in MnCl2 treated cells against target cells. This compared with 6.5 to 28.6 percent cytotoxicity in the control group. Interferon titers for MnCl2, and the two interferon inducer treated mice were 76, 162, and 290, respectively. This compared with an interferon titer of 23 for the control group. The authors conclude that Mn is capable of enhancing murine natural killer cell activity against certain tumor cells."
1238049,Bishop 1983,Manufacturing Processes: Sheepskin And Fur Processing,"Methods for preparing raw fur skins and sheep skins for use in garment manufacture or other commercial purposes are reviewed. Techniques employed in the dressing and dyeing of sheep skin are described. The carding, ironing, and shearing treatments are examined. Fur dressing involves soaking, fleshing, pickling, and oiling. By these means the skins are rehydrated, the fascia removed, the collagen fiber structure broken down, and the skin lubricated to prevent adherence of the fibers. Finishing involves the final presentation of the dressed skin and consists of the mechanical treatments of stretching, ironing, beating, carding, brushing and combing, glazing, grooving, and dyeing. Modern methods for performing each treatment are described. Traditional methods of fur dyeing are also considered. There are three main steps: killing, mordanting, and dyeing. Hydrogen-peroxide (7722841) and sodium-chlorate (7775099) are examples of agents used for killing which renders fur fibers more receptive to subsequent mordants and dyes. Common mordants are ferrous-sulfate (7720787), potassium-chromate (7789006), sodium-chromate (7775113), and copper-sulphate (7758987). The four classes of dyes in current use are enumerated.","Manufacturing Processes: Sheepskin And Fur Processing Abs: Methods for preparing raw fur skins and sheep skins for use in garment manufacture or other commercial purposes are reviewed. Techniques employed in the dressing and dyeing of sheep skin are described. The carding, ironing, and shearing treatments are examined. Fur dressing involves soaking, fleshing, pickling, and oiling. By these means the skins are rehydrated, the fascia removed, the collagen fiber structure broken down, and the skin lubricated to prevent adherence of the fibers. Finishing involves the final presentation of the dressed skin and consists of the mechanical treatments of stretching, ironing, beating, carding, brushing and combing, glazing, grooving, and dyeing. Modern methods for performing each treatment are described. Traditional methods of fur dyeing are also considered. There are three main steps: killing, mordanting, and dyeing. Hydrogen-peroxide (7722841) and sodium-chlorate (7775099) are examples of agents used for killing which renders fur fibers more receptive to subsequent mordants and dyes. Common mordants are ferrous-sulfate (7720787), potassium-chromate (7789006), sodium-chromate (7775113), and copper-sulphate (7758987). The four classes of dyes in current use are enumerated."
1238044,Walum 1982,Membrane Lesions in Cultured Mouse Neuroblastoma Cells Exposed to Metal Compounds,"A proposed method for screening heavy metal compounds for their membrane toxicity was developed. The method was based on preloading cultures of clone-41A3 mouse-neuroblastoma-C1300 cells with tritium (H-3) tagged 2-deoxy-D-glucose (dGlc). The cultures were perfused with phosphate buffered saline containing 1.0mg/ml D-glucose and various concentrations of the test compound for 60 minutes. Efflux of dGlc derived H3 activity into the perfusate which served as a marker for membrane damage was monitored. The membrane toxic concentration (MTC) was computed from the data. The technique was tested with up to 10(-3) molar (M) mercuric-chloride (7487947), methylmercuric-chloride (115093) (MMC), triethyltin-chloride (994310) (TETC), and potassium-dichromate (7778509). The MTCs of the compounds were: MMC, 9x10(-7)M; mercuric-chloride, 6x10(-6)M; TETC, 3x10(-4)M; and potassium-dichromate, 7x10(-4)M. The author concludes that ranking the membrane toxicity of the compounds according to their MTCs indicates that MMC is the most toxic followed by mercuric-chloride, TETC, and potassium-dichromate in that order. The ranking agrees with the results of previously published studies. This indicates that the proposed bioassay can be used to screen metal compounds for their nerve cell membrane toxicity.","Membrane Lesions in Cultured Mouse Neuroblastoma Cells Exposed to Metal Compounds Abs: A proposed method for screening heavy metal compounds for their membrane toxicity was developed. The method was based on preloading cultures of clone-41A3 mouse-neuroblastoma-C1300 cells with tritium (H-3) tagged 2-deoxy-D-glucose (dGlc). The cultures were perfused with phosphate buffered saline containing 1.0mg/ml D-glucose and various concentrations of the test compound for 60 minutes. Efflux of dGlc derived H3 activity into the perfusate which served as a marker for membrane damage was monitored. The membrane toxic concentration (MTC) was computed from the data. The technique was tested with up to 10(-3) molar (M) mercuric-chloride (7487947), methylmercuric-chloride (115093) (MMC), triethyltin-chloride (994310) (TETC), and potassium-dichromate (7778509). The MTCs of the compounds were: MMC, 9x10(-7)M; mercuric-chloride, 6x10(-6)M; TETC, 3x10(-4)M; and potassium-dichromate, 7x10(-4)M. The author concludes that ranking the membrane toxicity of the compounds according to their MTCs indicates that MMC is the most toxic followed by mercuric-chloride, TETC, and potassium-dichromate in that order. The ranking agrees with the results of previously published studies. This indicates that the proposed bioassay can be used to screen metal compounds for their nerve cell membrane toxicity."
1238042,Anonymous 1982,Information Profiles on Potential Occupational Hazards: Inorganic Chromium Compounds,"Information profiles were presented for the following inorganic chromium compounds deemed to be important because their commercial production exceeds 1 million pounds annually: chromic(VI)-acid (1333820), chromic(III)-hydroxide (1308141), chromic(III)-oxide (1308389), chromic(III)-sulfate (10101538), chromic(III)-sulfate (basic) (12336957), chromium-dioxide (12018018), potassium-dichromate(VI) (7778509), lead-chromate (7758976), sodium-chromate(VI) (7775113), sodium-dichromate(VI) (10588019), and zinc-yellow-chromate(VI) (37300235). Absorbed from the gastrointestinal tract, the respiratory tract, and damaged skin was described. Uptake depended on the chemical form. The highest levels of chromium retention occurred in the reticuloendothelial system, liver, spleen, and bone marrow of animals given chromite or chromium-chloride. Most excretion occurred through the urine. Hexavalent chromium compounds were more capable of crossing biological membranes than trivalent compounds and were more readily absorbed from the gut or through the skin. Biological effects of hexavalent chromium in humans included skin ulceration, dermatitis, nasal membrane irritation and ulceration, nasal septal perforation, rhinitis, nosebleed, nephritis, liver damage, epigastric pain, pulmonary congestion and edema, and erosion and discoloration of teeth. Chromium(VI) compounds caused mutations in a variety of systems. Exposure to trivalent chromium in the workplace has caused contact dermatitis and chrome ulcers. Epidemiological studies indicated respiratory carcinogenicity among workers occupationally exposed during chromate production.","Information Profiles on Potential Occupational Hazards: Inorganic Chromium Compounds Abs: Information profiles were presented for the following inorganic chromium compounds deemed to be important because their commercial production exceeds 1 million pounds annually: chromic(VI)-acid (1333820), chromic(III)-hydroxide (1308141), chromic(III)-oxide (1308389), chromic(III)-sulfate (10101538), chromic(III)-sulfate (basic) (12336957), chromium-dioxide (12018018), potassium-dichromate(VI) (7778509), lead-chromate (7758976), sodium-chromate(VI) (7775113), sodium-dichromate(VI) (10588019), and zinc-yellow-chromate(VI) (37300235). Absorbed from the gastrointestinal tract, the respiratory tract, and damaged skin was described. Uptake depended on the chemical form. The highest levels of chromium retention occurred in the reticuloendothelial system, liver, spleen, and bone marrow of animals given chromite or chromium-chloride. Most excretion occurred through the urine. Hexavalent chromium compounds were more capable of crossing biological membranes than trivalent compounds and were more readily absorbed from the gut or through the skin. Biological effects of hexavalent chromium in humans included skin ulceration, dermatitis, nasal membrane irritation and ulceration, nasal septal perforation, rhinitis, nosebleed, nephritis, liver damage, epigastric pain, pulmonary congestion and edema, and erosion and discoloration of teeth. Chromium(VI) compounds caused mutations in a variety of systems. Exposure to trivalent chromium in the workplace has caused contact dermatitis and chrome ulcers. Epidemiological studies indicated respiratory carcinogenicity among workers occupationally exposed during chromate production."
1238041,Adams 1982,Patch Testing in Occupational Dermatitis,"This appendix contained 12 guidelines to follow in patch testing for occupational dermatitis. These included the suggestions of testing only with known substances, use of the back as the best site, not testing if the dermatitis is very active, using the AL test material and covering with Norgeplaster or Dermicel tape, telling the patient to leave the patches on for 48 hours unless problems develop, instructing the patient not to shower or engage in sports, taking a preliminary reading at 48 hours when patches are removed and a final reading at 72 hours, distinguishing between irritations and allergic reactions, false negatives, determining relevance of positive tests, and providing the patient with a list of substances to avoid. The standard series of patch tests was applicable for nickel-sulfate (7786814), potassium-dichromate (7778509), neomycin-sulfate (1405103), ethylenediamine-dihydrochloride (333186), Balsam-of-Peru (8007009), benzyl-alcohol (100516), ammoniated-mercury (10124488), paraben mix, formaldehyde (50000), p-phenylenediamine (106503), cinnamic-alcohol (104541), cinnamic-aldehyde (104552), caine mix, wool alcohols, lanolin (hydrous), mercapto mix, thiuram mix, naphthyl mix, black rubber mix, carba mix, and epoxy resin. Additional substances for occupational dermatitis testing were listed. Sources for obtaining patch test materials were listed with their addresses.","Patch Testing in Occupational Dermatitis Abs: This appendix contained 12 guidelines to follow in patch testing for occupational dermatitis. These included the suggestions of testing only with known substances, use of the back as the best site, not testing if the dermatitis is very active, using the AL test material and covering with Norgeplaster or Dermicel tape, telling the patient to leave the patches on for 48 hours unless problems develop, instructing the patient not to shower or engage in sports, taking a preliminary reading at 48 hours when patches are removed and a final reading at 72 hours, distinguishing between irritations and allergic reactions, false negatives, determining relevance of positive tests, and providing the patient with a list of substances to avoid. The standard series of patch tests was applicable for nickel-sulfate (7786814), potassium-dichromate (7778509), neomycin-sulfate (1405103), ethylenediamine-dihydrochloride (333186), Balsam-of-Peru (8007009), benzyl-alcohol (100516), ammoniated-mercury (10124488), paraben mix, formaldehyde (50000), p-phenylenediamine (106503), cinnamic-alcohol (104541), cinnamic-aldehyde (104552), caine mix, wool alcohols, lanolin (hydrous), mercapto mix, thiuram mix, naphthyl mix, black rubber mix, carba mix, and epoxy resin. Additional substances for occupational dermatitis testing were listed. Sources for obtaining patch test materials were listed with their addresses."
1238040,Foussereau et al. 1982,Tanners,"Work related allergic reactions among tanners were reviewed with regard to the identification and nature of the allergens. The pretanning procedures of soaking, depilation, liming, deliming, pickling and bating as well as the chemicals used in these processes were described. Products used in vegetal tanning were listed: bark, ground wood, roots, leaves, fruits and saps or gums. The chemicals used in mineral tanning procedures were considered. The final operation in tanning, finishing or currying, was described. A list of allergens to be used in tests of tanners was presented. Potassium-dichromate (7778509), formaldehyde (50000) and dyes such paraphenylenediamine (106503), aniline derivatives and azoics have been found to be the most common allergens. Glue resin allergies in the shoe industry have also been observed. The authors note that tanner's allergic dermatitis is indistinguishable from other forms of occupational dermatitis. The progress of industrialization, whereby rolling bridges are used to pass leather from one vat to another, has resulted in reduced numbers of tannery workers developing allergic dermatitis.","Tanners Abs: Work related allergic reactions among tanners were reviewed with regard to the identification and nature of the allergens. The pretanning procedures of soaking, depilation, liming, deliming, pickling and bating as well as the chemicals used in these processes were described. Products used in vegetal tanning were listed: bark, ground wood, roots, leaves, fruits and saps or gums. The chemicals used in mineral tanning procedures were considered. The final operation in tanning, finishing or currying, was described. A list of allergens to be used in tests of tanners was presented. Potassium-dichromate (7778509), formaldehyde (50000) and dyes such paraphenylenediamine (106503), aniline derivatives and azoics have been found to be the most common allergens. Glue resin allergies in the shoe industry have also been observed. The authors note that tanner's allergic dermatitis is indistinguishable from other forms of occupational dermatitis. The progress of industrialization, whereby rolling bridges are used to pass leather from one vat to another, has resulted in reduced numbers of tannery workers developing allergic dermatitis."
1238039,Foussereau et al. 1982,Printers,"Allergic responses among printers were reviewed with regard to the identification and nature of the allergens. The procedures involved in printing were described including typography, engraving, lithography, offsetting and the dichromate colloid procedure. The structures of solvent soluble dyes and insoluble pigments, the two types of dyes used in printing, were presented. Classical allergens in printers including potassium-dichromate (7778509), azoic pigments and photograph developers were considered. The chemical structures of a number of allergenic azoic pigments were presented and the components of printing inks were listed. The development of new work procedures has resulted in the introduction of new contact allergens such as the monomers and diverse ingredients of plastics. Studies concerning allergies in workers using the Acrylic Dycril and Letterflex polyurethane procedures, and also ultra violet drying inks, were described. An inventory of allergens in printers was presented. The need to distinguish between allergic dermatitis and irritant dermatitis was emphasized. The authors note that due to the large number of ingredients in inks the causes of ink dermatitis can be difficult to establish.","Printers Abs: Allergic responses among printers were reviewed with regard to the identification and nature of the allergens. The procedures involved in printing were described including typography, engraving, lithography, offsetting and the dichromate colloid procedure. The structures of solvent soluble dyes and insoluble pigments, the two types of dyes used in printing, were presented. Classical allergens in printers including potassium-dichromate (7778509), azoic pigments and photograph developers were considered. The chemical structures of a number of allergenic azoic pigments were presented and the components of printing inks were listed. The development of new work procedures has resulted in the introduction of new contact allergens such as the monomers and diverse ingredients of plastics. Studies concerning allergies in workers using the Acrylic Dycril and Letterflex polyurethane procedures, and also ultra violet drying inks, were described. An inventory of allergens in printers was presented. The need to distinguish between allergic dermatitis and irritant dermatitis was emphasized. The authors note that due to the large number of ingredients in inks the causes of ink dermatitis can be difficult to establish."
1238038,Foussereau et al. 1982,Brick Layers,"Contact allergies in brick layers were reviewed with regard to the principal occupational allergens and clinical studies. The major form of contact allergy among brick layers has been found to be cement dermatitis, the major allergen being chromate cement. Hexavalent-chromium (18540299) at concentrations of a few parts per million has been found to induce allergic contact dermatitis. Studies have shown that trivalent-chromium (16065831) has no effect, but that trivalent-chromium of lime and clay is often oxidized to hexavalent-chromium during the cement making process. Contact allergies to cement cobalt (7440484), cement accelerators containing chromium (7440473), protective rubber gloves, protective leather gloves containing chromium, and plastics used as anticorrosives have been reported. Chromate sensitivity has been indicated as a dermatitis affecting the backs of the hands and the distal forearms. Studies have shown that cement induced allergic eczema is chronic even in the absence of further cement contact. The workers found to be at greatest risk of developing cement allergy are plasterers, tile layers and concrete workers manufacturing prefabricated walls. Patch testing with cement is usually negative due to absorption of the chromates into the cement upon hydration. The recommended method for chromate patch tests utilizes a 0.5 percent solution of potassium-dichromate in either water or petrolatum. Therapy for cement dermatitis was discussed including topical treatment with corticoids and systemic antibiotics for infection.","Brick Layers Abs: Contact allergies in brick layers were reviewed with regard to the principal occupational allergens and clinical studies. The major form of contact allergy among brick layers has been found to be cement dermatitis, the major allergen being chromate cement. Hexavalent-chromium (18540299) at concentrations of a few parts per million has been found to induce allergic contact dermatitis. Studies have shown that trivalent-chromium (16065831) has no effect, but that trivalent-chromium of lime and clay is often oxidized to hexavalent-chromium during the cement making process. Contact allergies to cement cobalt (7440484), cement accelerators containing chromium (7440473), protective rubber gloves, protective leather gloves containing chromium, and plastics used as anticorrosives have been reported. Chromate sensitivity has been indicated as a dermatitis affecting the backs of the hands and the distal forearms. Studies have shown that cement induced allergic eczema is chronic even in the absence of further cement contact. The workers found to be at greatest risk of developing cement allergy are plasterers, tile layers and concrete workers manufacturing prefabricated walls. Patch testing with cement is usually negative due to absorption of the chromates into the cement upon hydration. The recommended method for chromate patch tests utilizes a 0.5 percent solution of potassium-dichromate in either water or petrolatum. Therapy for cement dermatitis was discussed including topical treatment with corticoids and systemic antibiotics for infection."
1238037,Maltoni et al. 1982,Experimental Approach To The Assessment Of The Carcinogenic Risk Of Industrial Inorganic Pigments,"Carcinogenicity bioassays of the inorganic pigments chromium-yellow (7758976), chromium-orange (18454121), zinc-yellow (37300235), molybdenum-orange, cadmium-yellow (1306236), iron-yellow (51274001), iron-red (1309371), and titanium-oxide (13463677) were conducted. Sprague-Dawley-rats were injected subcutaneously (sc) with 30 milligrams of each pigment. Rats receiving sc injections of saline were used as controls. All animals were observed until death. Complete necropsies were performed. Chromium-yellow, chromium-orange, zinc-yellow, molybdenum-orange, and cadmium-yellow were definitely carcinogenic, molybdenum-orange being the most potent. Iron-red showed a borderline effect; one sarcoma was observed in 80 animals. The tumors observed were primarily rhabdomyosarcomas, fibrosarcomas, and mixed sarcomas (rhabdosarcomas/fibrosarcomas), occurring at the injection site. Titanium-oxide and iron-yellow did not show any carcinogenic activity. The authors note that molybdenum-orange was one of the most potent carcinogens they have ever tested. They conclude that inorganic pigments may represent a real carcinogenic risk for humans. They recommend conducting carcinogenesis bioassays of other inorganic pigments, conducting epidemiological surveys of exposed groups, especially painters, and immediately implementing medical surveillance of high risk groups, such as painters.","Experimental Approach To The Assessment Of The Carcinogenic Risk Of Industrial Inorganic Pigments Abs: Carcinogenicity bioassays of the inorganic pigments chromium-yellow (7758976), chromium-orange (18454121), zinc-yellow (37300235), molybdenum-orange, cadmium-yellow (1306236), iron-yellow (51274001), iron-red (1309371), and titanium-oxide (13463677) were conducted. Sprague-Dawley-rats were injected subcutaneously (sc) with 30 milligrams of each pigment. Rats receiving sc injections of saline were used as controls. All animals were observed until death. Complete necropsies were performed. Chromium-yellow, chromium-orange, zinc-yellow, molybdenum-orange, and cadmium-yellow were definitely carcinogenic, molybdenum-orange being the most potent. Iron-red showed a borderline effect; one sarcoma was observed in 80 animals. The tumors observed were primarily rhabdomyosarcomas, fibrosarcomas, and mixed sarcomas (rhabdosarcomas/fibrosarcomas), occurring at the injection site. Titanium-oxide and iron-yellow did not show any carcinogenic activity. The authors note that molybdenum-orange was one of the most potent carcinogens they have ever tested. They conclude that inorganic pigments may represent a real carcinogenic risk for humans. They recommend conducting carcinogenesis bioassays of other inorganic pigments, conducting epidemiological surveys of exposed groups, especially painters, and immediately implementing medical surveillance of high risk groups, such as painters."
1238036,Anonymous 1981,Chromium And Inorganic Compounds Of Chromium In Air. Laboratory Method Using X-Ray Fluorescence Spectrometry,"A method using X-ray fluorescence spectrometry was developed for measuring chromium (7440473) and inorganic compounds of chromium in air. The samples to be analyzed were loaded on membrane filters of 25 millimeters in diameter using precalibrated sampling pumps. The filters were placed in an X-ray spectrometer sample cup, making sure that the exposed surface was facing the incident X-ray fluorescence beam emanating under optimum conditions. A calibration procedure with 0 to 600 micrograms potassium-chromate was simultaneously run. The method was suitable for measuring 0.005 to 20 milligrams per cubic meter chromium in air; the detector response was linear up to a total filter loading of 600 micrograms for a typical dust sample. The precision of the method was better than 10 percent. Corrections were necessary if samples contained a high concentration of vanadium. The author concludes that the method is accurate and reliable.","Chromium And Inorganic Compounds Of Chromium In Air. Laboratory Method Using X-Ray Fluorescence Spectrometry Abs: A method using X-ray fluorescence spectrometry was developed for measuring chromium (7440473) and inorganic compounds of chromium in air. The samples to be analyzed were loaded on membrane filters of 25 millimeters in diameter using precalibrated sampling pumps. The filters were placed in an X-ray spectrometer sample cup, making sure that the exposed surface was facing the incident X-ray fluorescence beam emanating under optimum conditions. A calibration procedure with 0 to 600 micrograms potassium-chromate was simultaneously run. The method was suitable for measuring 0.005 to 20 milligrams per cubic meter chromium in air; the detector response was linear up to a total filter loading of 600 micrograms for a typical dust sample. The precision of the method was better than 10 percent. Corrections were necessary if samples contained a high concentration of vanadium. The author concludes that the method is accurate and reliable."
1238031,Korallus et al. 1982,[Relationships between hygienic measures and the bronchial carcinoma mortality in the chromate producing industry],"The relationship between change in production methods and industrial hygiene control measures and the incidence of bronchial carcinoma in German chromate (11104599) workers were examined. An epidemiological study of mortality data for the years 1978 and 1979 was performed in two chromate producing facilities and results were compared with data from the same facilities for the period 1948 to 1952. Incidence of nasal septum perforations was also determined. Between the two periods, there was a change from a high lime process to a lime free degradation of the ore which reduced the occurrence of calcium-chromate (13765190); industrial hygiene measures were also intensified during this period. Comparison of the standardized mortality ratio for lung cancer for the two test periods revealed a clearly decreasing tendency in both facilities. A retrospective analysis of matched pairs indicated that those who died of lung cancer entered the chromate facility earlier than those dying of other causes. The incidence of nasal septum perforations also showed a decline. The authors conclude that results confirm that changes in production methods and the use of industrial hygiene controls in the chromate processing industry have been effective. (German)","[Relationships between hygienic measures and the bronchial carcinoma mortality in the chromate producing industry] Abs: The relationship between change in production methods and industrial hygiene control measures and the incidence of bronchial carcinoma in German chromate (11104599) workers were examined. An epidemiological study of mortality data for the years 1978 and 1979 was performed in two chromate producing facilities and results were compared with data from the same facilities for the period 1948 to 1952. Incidence of nasal septum perforations was also determined. Between the two periods, there was a change from a high lime process to a lime free degradation of the ore which reduced the occurrence of calcium-chromate (13765190); industrial hygiene measures were also intensified during this period. Comparison of the standardized mortality ratio for lung cancer for the two test periods revealed a clearly decreasing tendency in both facilities. A retrospective analysis of matched pairs indicated that those who died of lung cancer entered the chromate facility earlier than those dying of other causes. The incidence of nasal septum perforations also showed a decline. The authors conclude that results confirm that changes in production methods and the use of industrial hygiene controls in the chromate processing industry have been effective. (German)"
1238028,Anonymous 1980,Summarization Of Recent Literature Pertaining To An Occupational Health Standard For Hexavalent Chromium,"Current literature on human and animal toxicology, analytical and sampling methods, work practices, and engineering controls on hexavalent chromium (18540299) is reviewed. Several reports indicate various dermatologic effects of hexavalent chromium including skin ulcers, dermatitis, and nasal perforations. Allergic sensitization in industrial workers is also reported to chromium compounds such as potassium-dichromate (7778509), and other compounds used in shoe industry (SIC-3131), nickel/chromium plating industry (SIC-3471) and in metaloplastic prosthesis industry (SIC-3842). Bronchial asthma, nodular pneumoconiosis, and upper respiratory disorders are produced by inhalation of dusts or fumes of chromium compounds. Several epidemiologic studies indicate increased carcinogenic risk associated with exposure to hexavalent chromium, although these studies are not adequately controlled. Animal studies have so far failed to provide data on carcinogenicity due to inhalation, although induction of local tumors at site of injection is observed for many chromium compounds. Recent literature contains data on mutagenic potential of hexavalent chromium and compounds. The authors conclude that the present NIOSH method of analysis for hexavalent chromium needs revision. In the presence of iron-oxide (1309371), as observed in the welding industry, the recovery of hexavalent chromium is as low as 1 percent. At present, no single method has been developed for analysis of chromium in blood and urine.","Summarization Of Recent Literature Pertaining To An Occupational Health Standard For Hexavalent Chromium Abs: Current literature on human and animal toxicology, analytical and sampling methods, work practices, and engineering controls on hexavalent chromium (18540299) is reviewed. Several reports indicate various dermatologic effects of hexavalent chromium including skin ulcers, dermatitis, and nasal perforations. Allergic sensitization in industrial workers is also reported to chromium compounds such as potassium-dichromate (7778509), and other compounds used in shoe industry (SIC-3131), nickel/chromium plating industry (SIC-3471) and in metaloplastic prosthesis industry (SIC-3842). Bronchial asthma, nodular pneumoconiosis, and upper respiratory disorders are produced by inhalation of dusts or fumes of chromium compounds. Several epidemiologic studies indicate increased carcinogenic risk associated with exposure to hexavalent chromium, although these studies are not adequately controlled. Animal studies have so far failed to provide data on carcinogenicity due to inhalation, although induction of local tumors at site of injection is observed for many chromium compounds. Recent literature contains data on mutagenic potential of hexavalent chromium and compounds. The authors conclude that the present NIOSH method of analysis for hexavalent chromium needs revision. In the presence of iron-oxide (1309371), as observed in the welding industry, the recovery of hexavalent chromium is as low as 1 percent. At present, no single method has been developed for analysis of chromium in blood and urine."
1238026,Kominsky et al. 1978,"Health Hazard Evaluation Determination Report No. HHE-77-127-516, Goodyear Aerospace Corporation, Akron, Ohio, August 1978","Environmental and medical surveys were conducted on March 28 and 29, 1978 to evaluate exposure to various paints and solvents by spray painters in Departments 541 and 661, at Goodyear Aerospace Corporation (SIC-3728) in Akron, Ohio. The evaluation was requested by an authorized representative of the United Automobile Aerospace and Agricultural Implement Workers of America, Local Number 856, on behalf of 22 affected employees. Environmental samples indicated airborne chromium(VI) (7440473) concentrations in excess of the 100 micrograms per cubic meter OSHA standard. None of the other test chemicals exceeded their respective environmental criteria. The medical surveys did not reveal conclusive evidence of exposure related symptoms. The authors conclude that the production spray painters in Department 661 are exposed to toxic concentrations of carcinogenic chromium(VI) as zinc-chromate (13530659). They recommend that existing environmental and medical surveillance programs be revised, that a respiratory protection program be provided and maintained until engineering controls are instituted, and that existing work practices and procedures be reviewed.","Health Hazard Evaluation Determination Report No. HHE-77-127-516, Goodyear Aerospace Corporation, Akron, Ohio, August 1978 Abs: Environmental and medical surveys were conducted on March 28 and 29, 1978 to evaluate exposure to various paints and solvents by spray painters in Departments 541 and 661, at Goodyear Aerospace Corporation (SIC-3728) in Akron, Ohio. The evaluation was requested by an authorized representative of the United Automobile Aerospace and Agricultural Implement Workers of America, Local Number 856, on behalf of 22 affected employees. Environmental samples indicated airborne chromium(VI) (7440473) concentrations in excess of the 100 micrograms per cubic meter OSHA standard. None of the other test chemicals exceeded their respective environmental criteria. The medical surveys did not reveal conclusive evidence of exposure related symptoms. The authors conclude that the production spray painters in Department 661 are exposed to toxic concentrations of carcinogenic chromium(VI) as zinc-chromate (13530659). They recommend that existing environmental and medical surveillance programs be revised, that a respiratory protection program be provided and maintained until engineering controls are instituted, and that existing work practices and procedures be reviewed."
1238025,Price 1979,"Health Hazard Evaluation Determination, Report No. HHE-78-13-577, Equitable Bag Company, Inc., Florence, Kentucky","Environmental sampling, analyses of wet stock paper, confidential employee interviews, observation of work practices, and a review of the workplace and materials used were conducted to evaluate the possible exposure of 20 employees to formaldehyde (50000) at the Equitable Bag Company, Incorporated (SIC-7399) in Florence Kentucky. The request was made by an authorized employee representative and the evaluation was performed on January 12, August 10 and 16, and September 20, 1978. Personal and area samples were analyzed for formaldehyde, acetaldehyde (75070) and valeraldehyde (110623). Propionaldehyde (123386) and butyraldehyde (123728) content also was measured. Personal and area samples for formaldehyde ranged from 0.14 to 0.09 parts per million (ppm), and were below the OSHA 8 hour time weighted average exposure limit of 3ppm. Environmental samples for total aldehydes were below the analytical limits of detection. During medical interviews, workers complained of respiratory and eye irritations, chest discomfort, and dermatitis. The reports of symptoms were more common during the summer months. The author concludes that a potential for excessive formaldehyde exposure did exist especially during warm weather and recommends that a maximum number of exhaust fans be used during periods of elevated temperatures, additional ventilation be installed at locations where wet stock paper is processed or stored, periodic sampling be conducted to prevent overexposures to formaldehyde, and precautions be taken to avoid needless environmental contamination from bags of lead chromate pigment stored in the facility.","Health Hazard Evaluation Determination, Report No. HHE-78-13-577, Equitable Bag Company, Inc., Florence, Kentucky Abs: Environmental sampling, analyses of wet stock paper, confidential employee interviews, observation of work practices, and a review of the workplace and materials used were conducted to evaluate the possible exposure of 20 employees to formaldehyde (50000) at the Equitable Bag Company, Incorporated (SIC-7399) in Florence Kentucky. The request was made by an authorized employee representative and the evaluation was performed on January 12, August 10 and 16, and September 20, 1978. Personal and area samples were analyzed for formaldehyde, acetaldehyde (75070) and valeraldehyde (110623). Propionaldehyde (123386) and butyraldehyde (123728) content also was measured. Personal and area samples for formaldehyde ranged from 0.14 to 0.09 parts per million (ppm), and were below the OSHA 8 hour time weighted average exposure limit of 3ppm. Environmental samples for total aldehydes were below the analytical limits of detection. During medical interviews, workers complained of respiratory and eye irritations, chest discomfort, and dermatitis. The reports of symptoms were more common during the summer months. The author concludes that a potential for excessive formaldehyde exposure did exist especially during warm weather and recommends that a maximum number of exhaust fans be used during periods of elevated temperatures, additional ventilation be installed at locations where wet stock paper is processed or stored, periodic sampling be conducted to prevent overexposures to formaldehyde, and precautions be taken to avoid needless environmental contamination from bags of lead chromate pigment stored in the facility."
1238020,Willey et al. 1977,A Solid Sorbent Personal Sampling Method for the Simultaneous Collection of Nitrogen Dioxide and Nitric Oxide in Air,"A solid sorbent sampling tube for nitrogen-dioxide (10102440) (NO2) and nitric-oxide (10102439) (NO) was developed for sampling in the concentration range of the proposed NIOSH standards of 1 and 25 parts per million (ppm) for workplace NO2 and NO, respectively. The sampling tube contained two 400 milligram (mg) sections of triethylamine (TEA) impregnated molecular sieve and one 800mg section of oxidizer in a glass tube. Air containing between 3 and 6ppm NO2 was passed through the tube at rates up to 150 cubic centimeters per minute. The collection efficiency of the tube was 100 percent. The amount of NO2 collected in the first TEA section was dependent upon the section mass. Approximately 97 percent of a sample of 3ppm NO2 was retained by 400mg of TEA. NO recovery was limited by the use of chromium-trioxide as oxidizer. Use of the Drager oxidizer yielded approximately 100 percent recovery of a sample of 5ppm NO passed through tubes containing 300mg TEA. Approximately 84 percent recovery of NO as NO2 was obtained for samples of 25ppm NO with a tube containing 400mg TEA. The application of the tube to an occupational environment was described.","A Solid Sorbent Personal Sampling Method for the Simultaneous Collection of Nitrogen Dioxide and Nitric Oxide in Air Abs: A solid sorbent sampling tube for nitrogen-dioxide (10102440) (NO2) and nitric-oxide (10102439) (NO) was developed for sampling in the concentration range of the proposed NIOSH standards of 1 and 25 parts per million (ppm) for workplace NO2 and NO, respectively. The sampling tube contained two 400 milligram (mg) sections of triethylamine (TEA) impregnated molecular sieve and one 800mg section of oxidizer in a glass tube. Air containing between 3 and 6ppm NO2 was passed through the tube at rates up to 150 cubic centimeters per minute. The collection efficiency of the tube was 100 percent. The amount of NO2 collected in the first TEA section was dependent upon the section mass. Approximately 97 percent of a sample of 3ppm NO2 was retained by 400mg of TEA. NO recovery was limited by the use of chromium-trioxide as oxidizer. Use of the Drager oxidizer yielded approximately 100 percent recovery of a sample of 5ppm NO passed through tubes containing 300mg TEA. Approximately 84 percent recovery of NO as NO2 was obtained for samples of 25ppm NO with a tube containing 400mg TEA. The application of the tube to an occupational environment was described."
1238019,Tsendrovskaya 1979,Determination of Triethylamine in Air by Thin-Layer Chromatography,"A sensitive method for the determination of triethylamine (121448) (TEA) in air using thin layer chromatography was described. The technique utilized 0.01 normal hydrochloric-acid as the absorbing solution and silica gel KSK as the sorbent. A mixture of acetone, water, and glacial acetic-acid in a proportions of 19 parts to 3 parts to 0.5 part served as the mobile solvent system. TEA detection by potassium-chromate solution required several micrograms of TEA whereas detection by iodine vapor was effective at a level of 0.9 microgram TEA. A linear relationship between spot size and TEA concentration on the plates was found for TEA levels between 1 and 20 micrograms. The formation of nonvolatile TEA salts were confirmed by the interaction of TEA with bromothymol-blue followed by colorimetry of the chloroform extracts. Determination of TEA in the atmosphere of industrial environments utilized an absorber with a porous plate containing 5 milliliters of 0.01 normal hydrochloric-acid. (Russian)","Determination of Triethylamine in Air by Thin-Layer Chromatography Abs: A sensitive method for the determination of triethylamine (121448) (TEA) in air using thin layer chromatography was described. The technique utilized 0.01 normal hydrochloric-acid as the absorbing solution and silica gel KSK as the sorbent. A mixture of acetone, water, and glacial acetic-acid in a proportions of 19 parts to 3 parts to 0.5 part served as the mobile solvent system. TEA detection by potassium-chromate solution required several micrograms of TEA whereas detection by iodine vapor was effective at a level of 0.9 microgram TEA. A linear relationship between spot size and TEA concentration on the plates was found for TEA levels between 1 and 20 micrograms. The formation of nonvolatile TEA salts were confirmed by the interaction of TEA with bromothymol-blue followed by colorimetry of the chloroform extracts. Determination of TEA in the atmosphere of industrial environments utilized an absorber with a porous plate containing 5 milliliters of 0.01 normal hydrochloric-acid. (Russian)"
1238017,Rutherford et al. 1979,A Simple Method for Screening Petroleum Effluents by In Vitro Enzyme Inhibition,"A method for screening petroleum effluents by in-vitro enzyme inhibition was described. The procedure was based on determining the extent of inhibition of glucose-6-phosphate-dehydrogenase (G6PDH). The procedure was developed using a simulated petroleum effluent (ARM) containing 10 milligrams (mg) ammonium-chloride, 10mg number 2 fuel oil, 0.25mg potassium-chromate, 0.1mg phenol, 0.17mg sodium-sulfide, and 20mg kaolinite in 1 liter diluent. Inhibition of G6PDH activity was tested by adding 10 microliters (microl) of G6PDH and 1 milliliter (ml) of ARM to a 3ml test tube. After 30 minutes preincubation in a water bath at 23 degrees-C, the sample was added to 1ml of a G6PDH reaction mixture containing 1.0 millimolar (mM) nicotinamide-adenine-dinucleotide-phosphate (NADP+) and 1.0mM glucose-6-phosphate (G6P) in 0.05 molar Tris-hydrochloride buffer, pH 8.1. The maximum reaction velocity was determined by following the production of reduced nicotinamide-adenine-dinucleotide-phosphate spectrophotometrically. The percentage inhibition was calculated by comparing the rate obtained with control enzyme which was preincubated without ARM. Alternatively, a visual colorimetric assay was used. A 10microl portion of the preincubation mixture was added to 5ml of a G6PDH reaction mixture containing 0.13mM NADP+, 5.0mM G6P, and 0.5mM 2,6-dichlorophenol-phenazine-methosulfate dye in 0.3 molar Tris. After adding 1ml distilled water, the mixture was incubated at 23 degrees-C until the dye was reduced to its colorless form. The time required for the blue color to disappear was recorded and compared with the time for the control mixture. The method was tested using ARM in seawater and freshwater. Maximal inhibition was 87 percent in freshwater and 60 percent in seawater. The visual assay showed a similar inhibition curve to that of the spectrophotometric assay. The authors conclude that the procedure may be a viable screening tool for refinery effluents.","A Simple Method for Screening Petroleum Effluents by In Vitro Enzyme Inhibition Abs: A method for screening petroleum effluents by in-vitro enzyme inhibition was described. The procedure was based on determining the extent of inhibition of glucose-6-phosphate-dehydrogenase (G6PDH). The procedure was developed using a simulated petroleum effluent (ARM) containing 10 milligrams (mg) ammonium-chloride, 10mg number 2 fuel oil, 0.25mg potassium-chromate, 0.1mg phenol, 0.17mg sodium-sulfide, and 20mg kaolinite in 1 liter diluent. Inhibition of G6PDH activity was tested by adding 10 microliters (microl) of G6PDH and 1 milliliter (ml) of ARM to a 3ml test tube. After 30 minutes preincubation in a water bath at 23 degrees-C, the sample was added to 1ml of a G6PDH reaction mixture containing 1.0 millimolar (mM) nicotinamide-adenine-dinucleotide-phosphate (NADP+) and 1.0mM glucose-6-phosphate (G6P) in 0.05 molar Tris-hydrochloride buffer, pH 8.1. The maximum reaction velocity was determined by following the production of reduced nicotinamide-adenine-dinucleotide-phosphate spectrophotometrically. The percentage inhibition was calculated by comparing the rate obtained with control enzyme which was preincubated without ARM. Alternatively, a visual colorimetric assay was used. A 10microl portion of the preincubation mixture was added to 5ml of a G6PDH reaction mixture containing 0.13mM NADP+, 5.0mM G6P, and 0.5mM 2,6-dichlorophenol-phenazine-methosulfate dye in 0.3 molar Tris. After adding 1ml distilled water, the mixture was incubated at 23 degrees-C until the dye was reduced to its colorless form. The time required for the blue color to disappear was recorded and compared with the time for the control mixture. The method was tested using ARM in seawater and freshwater. Maximal inhibition was 87 percent in freshwater and 60 percent in seawater. The visual assay showed a similar inhibition curve to that of the spectrophotometric assay. The authors conclude that the procedure may be a viable screening tool for refinery effluents."
1238014,Davis 1978,Continuous Mass Spectrometric Analysis Of Environmental Pollutants Using Surface Ionization,"An instrument for analyzing gaseous and particulate impurities in air was tested. The sample inlet system and ion source chamber was designed so that air was impinged on a small hole about 0.71 millimeter in diameter. Most of the air was removed by a mechanical pump. Samples of particles and air were passed through the hole and impinged on a rhenium ribbon heated by an electrical current. The ions produced were analyzed by mass spectrometry. Ribbon temperature was measured. Optimum ribbon temperature was between 800 and 1,000 degrees-K. Organic and inorganic compounds and water were analyzed. The number of ions produced by particles of chromium-oxide (11118573), copper-oxide (1344703), and lead-oxide (1335257) was determined. There was an abrupt increase in emission of metal ions as the particles hit the ribbon. The minimum amount of sodium, potassium, and cesium detectable was 1,000 atoms. Organic compounds with ionization efficiencies of up to 20 percent were detected at concentrations of 1 picogram per cubic meter. Water was analyzed by forming an aerosol. The author concludes that low amounts of impurities in air and water can be continuously analyzed using surface ionization mass spectrometry.","Continuous Mass Spectrometric Analysis Of Environmental Pollutants Using Surface Ionization Abs: An instrument for analyzing gaseous and particulate impurities in air was tested. The sample inlet system and ion source chamber was designed so that air was impinged on a small hole about 0.71 millimeter in diameter. Most of the air was removed by a mechanical pump. Samples of particles and air were passed through the hole and impinged on a rhenium ribbon heated by an electrical current. The ions produced were analyzed by mass spectrometry. Ribbon temperature was measured. Optimum ribbon temperature was between 800 and 1,000 degrees-K. Organic and inorganic compounds and water were analyzed. The number of ions produced by particles of chromium-oxide (11118573), copper-oxide (1344703), and lead-oxide (1335257) was determined. There was an abrupt increase in emission of metal ions as the particles hit the ribbon. The minimum amount of sodium, potassium, and cesium detectable was 1,000 atoms. Organic compounds with ionization efficiencies of up to 20 percent were detected at concentrations of 1 picogram per cubic meter. Water was analyzed by forming an aerosol. The author concludes that low amounts of impurities in air and water can be continuously analyzed using surface ionization mass spectrometry."
1238013,Lucas 1976,"Health Hazard Evaluation Determination, Report No. HHE-74-111-283, Cook Paint and Varnish Company, North Kansas City, Missouri, April 1976","Personal and general air samples were taken and employee interviews were completed at Cook Paint and Varnish Company (SIC-2851) in North Kansas City, Missouri on October 23, 1974, May 5, and September 5 and 15, 1975. An authorized representative of the Brotherhood of Painters and Allied Trades, AFL-CIO requested the evaluation on behalf of 5 affected employees. Particulate samples were collected. Standard analytical methods were used to analyze total dust, respirable dust, stannous-octoate (301100), and chromic-oxide (1308389). Trimellitic-anhydride (552307) (TMA) samples were analyzed by rapid esterification gas chromatography. Past occupational history and illness were reviewed. Physical examination revealed eye and nasal irritation, shortness of breath, wheezing and cough, gastric distress, headache, and photophobia. Results of sampling indicated that exposure to chromic-oxide and stannous octoate were less than 40% of the OSHA criteria of 1 and 2 milligrams per cubic meter (mg/m3) respectively. Exposure to TMA ranged from 0.1 to 7.5mg/m3, which exceeded the criteria of 0.1mg/m3 suggested by the authors because there are no current NIOSH guidelines or OSHA standards for TMA. Total airborne particulate dusts ranging from 3 to 77mg/m3 exceeded the Threshold Limit Value of 10mg/m3 for total nuisance dusts. The authors conclude that a health hazard exists at this site because workers were exposed to toxic concentrations of particulate matter and TMA. The authors recommend modifications in the ventilation, respiratory program, work hazard education and physical examination programs.","Health Hazard Evaluation Determination, Report No. HHE-74-111-283, Cook Paint and Varnish Company, North Kansas City, Missouri, April 1976 Abs: Personal and general air samples were taken and employee interviews were completed at Cook Paint and Varnish Company (SIC-2851) in North Kansas City, Missouri on October 23, 1974, May 5, and September 5 and 15, 1975. An authorized representative of the Brotherhood of Painters and Allied Trades, AFL-CIO requested the evaluation on behalf of 5 affected employees. Particulate samples were collected. Standard analytical methods were used to analyze total dust, respirable dust, stannous-octoate (301100), and chromic-oxide (1308389). Trimellitic-anhydride (552307) (TMA) samples were analyzed by rapid esterification gas chromatography. Past occupational history and illness were reviewed. Physical examination revealed eye and nasal irritation, shortness of breath, wheezing and cough, gastric distress, headache, and photophobia. Results of sampling indicated that exposure to chromic-oxide and stannous octoate were less than 40% of the OSHA criteria of 1 and 2 milligrams per cubic meter (mg/m3) respectively. Exposure to TMA ranged from 0.1 to 7.5mg/m3, which exceeded the criteria of 0.1mg/m3 suggested by the authors because there are no current NIOSH guidelines or OSHA standards for TMA. Total airborne particulate dusts ranging from 3 to 77mg/m3 exceeded the Threshold Limit Value of 10mg/m3 for total nuisance dusts. The authors conclude that a health hazard exists at this site because workers were exposed to toxic concentrations of particulate matter and TMA. The authors recommend modifications in the ventilation, respiratory program, work hazard education and physical examination programs."
1238012,Collins et al. 1972,Estimation of Polychlorobiphenyls,"Methods are described for separation of polychlorinated-biphenyls (671169) (PCBs) from organo chlorine residues by adsorption chromatography, and for quantitation of PCBs by gas/liquid or thin-layer chromatography, or both. Preliminary steps involve cleaning and processing extracts in the manner used for organo chlorine pesticide residue determination. The samples, in either dry hexane (110543) or light petroleum (8002059), are then applied to a silica-gel adsorption column to separate PCBs from organo pesticide residues. Residual p,p-DDE (72548) in the PCB fraction is then oxidized to 4,4'-dichlorobenzophenone (90982) by use of acetic-acid (64197), n-hexane (110543), a sodium-hydroxide (1310732) solution, and recrystallized chromium-trioxide (1333820). PCB levels can then be determined by either gas/liquid chromatography, thin-layer chromatography, or both. For quantitation, the peak heights and retention times of the PCB material attributed to PCBs on the chromatogram were determined. Each peak height was multiplied by the corresponding retention time and the sum of all such products determined. This sum was divided by the product of the peak height and retention time for 1 nanogram of p,p-DDE injected on the same column, giving a direct estimate of weight (in nanograms) of PCBs in the sample applied to the column. This procedure has given recoveries of PCB from spiked samples ranging from 85 percent to 100 percent.","Estimation of Polychlorobiphenyls Abs: Methods are described for separation of polychlorinated-biphenyls (671169) (PCBs) from organo chlorine residues by adsorption chromatography, and for quantitation of PCBs by gas/liquid or thin-layer chromatography, or both. Preliminary steps involve cleaning and processing extracts in the manner used for organo chlorine pesticide residue determination. The samples, in either dry hexane (110543) or light petroleum (8002059), are then applied to a silica-gel adsorption column to separate PCBs from organo pesticide residues. Residual p,p-DDE (72548) in the PCB fraction is then oxidized to 4,4'-dichlorobenzophenone (90982) by use of acetic-acid (64197), n-hexane (110543), a sodium-hydroxide (1310732) solution, and recrystallized chromium-trioxide (1333820). PCB levels can then be determined by either gas/liquid chromatography, thin-layer chromatography, or both. For quantitation, the peak heights and retention times of the PCB material attributed to PCBs on the chromatogram were determined. Each peak height was multiplied by the corresponding retention time and the sum of all such products determined. This sum was divided by the product of the peak height and retention time for 1 nanogram of p,p-DDE injected on the same column, giving a direct estimate of weight (in nanograms) of PCBs in the sample applied to the column. This procedure has given recoveries of PCB from spiked samples ranging from 85 percent to 100 percent."
1238011,Laskin 1972,Chromate Compounds,"A chronic inhalation study on rats inhaling calcium-chromate (13907454) aerosols at 2 milligram per cubic meter concentration shows the incidence of keratinizing squamous cell carcinoma of the lung, one laryngeal squamous cell carcinoma with invasion of perineural spaces and adjoining cartilaginous rings and one malignant peritruncal tumor of undetermined type and origin. In the hamsters, a squamous cell carcinoma of the larynx is found invading and destroying the cartilage. Results indicate the residue step of processing as the major source of carcinogenic exposure for the industrial workers.","Chromate Compounds Abs: A chronic inhalation study on rats inhaling calcium-chromate (13907454) aerosols at 2 milligram per cubic meter concentration shows the incidence of keratinizing squamous cell carcinoma of the lung, one laryngeal squamous cell carcinoma with invasion of perineural spaces and adjoining cartilaginous rings and one malignant peritruncal tumor of undetermined type and origin. In the hamsters, a squamous cell carcinoma of the larynx is found invading and destroying the cartilage. Results indicate the residue step of processing as the major source of carcinogenic exposure for the industrial workers."
1238010,Zekeev et al. 1973,Blastomogenic Activity of Chrome Substances,"Histological examination of the lungs of rats following chromium-oxide administration shows that the compound has definite blastomogenic properties. Exposure to chromite and dolomite dust does not result in the development of any precancerous changes, but lungs show a suppurative inflammatory process, indicative of the high toxicity of the compounds. Sodium-bichromate (10588019) induces an intensive inflammatory process in the lungs; ammonium-bichromate (7789095) through less toxic manifests definite blastomogenic activity in combination with non-carcinogenic doses of 3,4-benzpyrene (50328). (Russian: English translation available)","Blastomogenic Activity of Chrome Substances Abs: Histological examination of the lungs of rats following chromium-oxide administration shows that the compound has definite blastomogenic properties. Exposure to chromite and dolomite dust does not result in the development of any precancerous changes, but lungs show a suppurative inflammatory process, indicative of the high toxicity of the compounds. Sodium-bichromate (10588019) induces an intensive inflammatory process in the lungs; ammonium-bichromate (7789095) through less toxic manifests definite blastomogenic activity in combination with non-carcinogenic doses of 3,4-benzpyrene (50328). (Russian: English translation available)"
1238008,Clark 1976,Thermal Analysis and Thermal Batteries,"Some applications of thermal analysis to studying problems associated with thermal batteries are presented. A definition of thermal batteries is given. Applications include the study of the thermal decomposition of zinc chromates, the thermal stability of Vespel (a high-temperature polyimide used as a rigid insulating material), determining phase diagrams for the salt systems that are used in the thermal batteries, measurements of heats of reaction or reactions between some of the thermal battery constituents.","Thermal Analysis and Thermal Batteries Abs: Some applications of thermal analysis to studying problems associated with thermal batteries are presented. A definition of thermal batteries is given. Applications include the study of the thermal decomposition of zinc chromates, the thermal stability of Vespel (a high-temperature polyimide used as a rigid insulating material), determining phase diagrams for the salt systems that are used in the thermal batteries, measurements of heats of reaction or reactions between some of the thermal battery constituents."
1238007,Anonymous 1975,Information Concerning the Potential Carcinogenicity of Chromate Pigments,"Background material and correspondence concerning the potential carcinogenicity of chromate pigments, prepared by NIOSH after a notification by the Dry Color Manufacturers Association. Topics include history of chromium (7440473); chemistry of chromium; production of chromate pigments, such as chrome-yellow (lead-chromate), molybdate chrome-orange (1308298) (lead-chromate, lead-sulfate (7789062), and lead-molybdate), chrome-oxide-green (chrome oxide), chrome-green (1308389) (lead-chromate and ferriferrocyanide-blue), zinc-yellow (zinc-chromate (1328672)), and strontium-chromate (7446142); toxic effects on human skin; respiratory and gastrointestinal disorders, and cancer of the lung. The effects on animals and humans are found to be similar.","Information Concerning the Potential Carcinogenicity of Chromate Pigments Abs: Background material and correspondence concerning the potential carcinogenicity of chromate pigments, prepared by NIOSH after a notification by the Dry Color Manufacturers Association. Topics include history of chromium (7440473); chemistry of chromium; production of chromate pigments, such as chrome-yellow (lead-chromate), molybdate chrome-orange (1308298) (lead-chromate, lead-sulfate (7789062), and lead-molybdate), chrome-oxide-green (chrome oxide), chrome-green (1308389) (lead-chromate and ferriferrocyanide-blue), zinc-yellow (zinc-chromate (1328672)), and strontium-chromate (7446142); toxic effects on human skin; respiratory and gastrointestinal disorders, and cancer of the lung. The effects on animals and humans are found to be similar."
1238000,Archer 1975,Separation And Identification Of Minor Components In Smokeless Powders By Thin-Layer Chromatography,"The use of solvent systems and spray reagents for separation and identification of minor components of smokeless powder was assessed using thin layer chromatography (TLC). TLC was carried out on silica gel coated glass plates. The solvent systems used were: benzene, benzene/light and petroleum/ethylacetate in the volumetric proportion of 12/12/1, benzene/light and petroleum at 1/1, benzene/chloroform at 1/1, chloroform, or benzene/methanol at 4/1. The four spray reagents used were: vanillin in acetic-acid and orthophosphoric-acid; fresh mixture of ethanol, acetone and tetramethylammonium-hydroxide; sulfanilic-acid, 1-naphthylamine and acetic-acid; and potassium-dichromate, water and sulfuric-acid. The compounds were identified by the colored reaction products formed by the spray reagents on the TLC plate either visually or under ultraviolet light. Powder samples were extracted with dichloromethane and concentrated before application onto the TLC plates. The chromatograms were developed with one of the solvent systems. The developed plates were sprayed with the alkaline acetone reagent, then heated to 120 degrees-C for 10 minutes, cooled and then sprayed with sulfanilic-acid reagent. At each step, the appearance of colored products, if any, was noted. Further development with other solvent systems and developing reagents depended on the results obtained after the initial experiment. A range of 42 samples of smokeless powders from various manufacturers was examined. The compounds identified included aromatic amines, aliphatic nitrate esters, and nitrosamines. N-phenylurea, 1,3-diphenylurea, and 1,1-diphenylurea were not well resolved in the benzene/chloroform solvent system but were separated using chloroform. Nitroguanidine was separated with N-phenylurea and diphenylurea was separated with benzene/methanol. The author concludes that these spray reagents are reasonably sensitive for the identification of smokeless powder components.","Separation And Identification Of Minor Components In Smokeless Powders By Thin-Layer Chromatography Abs: The use of solvent systems and spray reagents for separation and identification of minor components of smokeless powder was assessed using thin layer chromatography (TLC). TLC was carried out on silica gel coated glass plates. The solvent systems used were: benzene, benzene/light and petroleum/ethylacetate in the volumetric proportion of 12/12/1, benzene/light and petroleum at 1/1, benzene/chloroform at 1/1, chloroform, or benzene/methanol at 4/1. The four spray reagents used were: vanillin in acetic-acid and orthophosphoric-acid; fresh mixture of ethanol, acetone and tetramethylammonium-hydroxide; sulfanilic-acid, 1-naphthylamine and acetic-acid; and potassium-dichromate, water and sulfuric-acid. The compounds were identified by the colored reaction products formed by the spray reagents on the TLC plate either visually or under ultraviolet light. Powder samples were extracted with dichloromethane and concentrated before application onto the TLC plates. The chromatograms were developed with one of the solvent systems. The developed plates were sprayed with the alkaline acetone reagent, then heated to 120 degrees-C for 10 minutes, cooled and then sprayed with sulfanilic-acid reagent. At each step, the appearance of colored products, if any, was noted. Further development with other solvent systems and developing reagents depended on the results obtained after the initial experiment. A range of 42 samples of smokeless powders from various manufacturers was examined. The compounds identified included aromatic amines, aliphatic nitrate esters, and nitrosamines. N-phenylurea, 1,3-diphenylurea, and 1,1-diphenylurea were not well resolved in the benzene/chloroform solvent system but were separated using chloroform. Nitroguanidine was separated with N-phenylurea and diphenylurea was separated with benzene/methanol. The author concludes that these spray reagents are reasonably sensitive for the identification of smokeless powder components."
1237999,Burnett and  Diamond 1973,Industrial Hygiene Evaluation Of Spray Applications Polyurethane Coatings,"Air samples were collected and analyzed for hexamethylene-diisocyanate (822060) (HMDI), toluene-diisocyanate (26471625) (TDI), methyl-isobutyl-ketone (108101) (MIK), methyl-ethyl-ketone (78933) (MEK), and strontium-chromate (7789062) (chromate) at McClellan Air Force Base, California. The survey was requested by the Chief of Bioengineering Services because of complaints of eye and skin irritation among workers in the aircraft painting facility. Solvent vapors were sampled by drawing air through activated charcoal tubes. Extraction was performed with carbon-disulfide, and analysis was made by gas chromatography and mass spectrometry. HMDI and TDI were sampled with impingers and analyzed by spectrophotometry. Samples were taken from three aircraft painting processes. During the solvent cleaning phase the following average concentrations, in parts per million (ppm), were found in breathing zone samples: MIK, 164; MEK, 215; and TDI, 198. The threshold limit values (TLV) for MIK, MEK, and TDI were 100, 200, and 100, respectively. During application of epoxy an average chromate concentration of 0.44 milligrams per cubic meter was measured, exceeding the TLV of 0.1ppm. HMDI concentrations during urethane (51796) application averaged 0.47ppm. The author concludes that excessive exposure to HMDI exists during the cleaning of aircraft surfaces with solvent. Improved respiratory and skin protection is recommended.","Industrial Hygiene Evaluation Of Spray Applications Polyurethane Coatings Abs: Air samples were collected and analyzed for hexamethylene-diisocyanate (822060) (HMDI), toluene-diisocyanate (26471625) (TDI), methyl-isobutyl-ketone (108101) (MIK), methyl-ethyl-ketone (78933) (MEK), and strontium-chromate (7789062) (chromate) at McClellan Air Force Base, California. The survey was requested by the Chief of Bioengineering Services because of complaints of eye and skin irritation among workers in the aircraft painting facility. Solvent vapors were sampled by drawing air through activated charcoal tubes. Extraction was performed with carbon-disulfide, and analysis was made by gas chromatography and mass spectrometry. HMDI and TDI were sampled with impingers and analyzed by spectrophotometry. Samples were taken from three aircraft painting processes. During the solvent cleaning phase the following average concentrations, in parts per million (ppm), were found in breathing zone samples: MIK, 164; MEK, 215; and TDI, 198. The threshold limit values (TLV) for MIK, MEK, and TDI were 100, 200, and 100, respectively. During application of epoxy an average chromate concentration of 0.44 milligrams per cubic meter was measured, exceeding the TLV of 0.1ppm. HMDI concentrations during urethane (51796) application averaged 0.47ppm. The author concludes that excessive exposure to HMDI exists during the cleaning of aircraft surfaces with solvent. Improved respiratory and skin protection is recommended."
1237997,Ehrlich and  Fenters 1972,Interactions Of Various Air Pollutants On Causation Of Pulmonary Disease,"The effects of long term exposure of squirrel-monkeys to nitrogen-dioxide (10102440) (NO2), of various concentrations of nickel-oxide (1313991) (NiO) on the resistance of Syrian-golden-hamsters to influenza virus and bacterial pneumonia, and of single and multiple exposures to chromium-trioxide (1333820) (CrO3) aerosol on the resistance of mice to influenza virus and pneumonia were investigated. Monkeys were exposed to 1 part per million (ppm) NO2 24 hours per day for 493 days and challenged with A/8 influenza virus. Hamsters were injected with 1, 5, 7.5, and 10 milligrams (mg) NiO particles. At 1, 6, and 24 hours they were challenged with Klebsiella-pneumoniae aerosol. Hamsters were challenged with influenza virus at 1, 24, and 48 hours before or after NiO doses of 1, 2.5, and 7.5mg. Swiss-Webster-mice were exposed to 3 to 12 microliters per liter of air of CrO3 and challenged with the virus or bacteria before and after exposure. Some mice were exposed to CrO3 and NO2. Exposure to NO2 caused the production of serum neutralization antibodies within 21 days after virus infection in monkeys. Slight emphysema and thickened bronchial epithelium were observed during histopathological studies. Mortality was enhanced in hamsters infected with bacteria within 1 hour after 5 or 7.5mg NiO, but not with 1 and 10mg. Increased mortality was also noted in virus infected hamsters. Histopathological examination of lung tissue of virus challenged hamsters revealed hyperplastic epithelium, adenomatosis, and thickened pleura. Single or multiple exposure to CrO3 aerosol did not enhance mortality in mice challenged with the bacteria or virus. A combination of CrO3 and NO2 exposure had no effect on mortalities. CrO3 particles were observed in the alveoli and alveolar ducts during histopathological examination./TRANSMISSION","Interactions Of Various Air Pollutants On Causation Of Pulmonary Disease Abs: The effects of long term exposure of squirrel-monkeys to nitrogen-dioxide (10102440) (NO2), of various concentrations of nickel-oxide (1313991) (NiO) on the resistance of Syrian-golden-hamsters to influenza virus and bacterial pneumonia, and of single and multiple exposures to chromium-trioxide (1333820) (CrO3) aerosol on the resistance of mice to influenza virus and pneumonia were investigated. Monkeys were exposed to 1 part per million (ppm) NO2 24 hours per day for 493 days and challenged with A/8 influenza virus. Hamsters were injected with 1, 5, 7.5, and 10 milligrams (mg) NiO particles. At 1, 6, and 24 hours they were challenged with Klebsiella-pneumoniae aerosol. Hamsters were challenged with influenza virus at 1, 24, and 48 hours before or after NiO doses of 1, 2.5, and 7.5mg. Swiss-Webster-mice were exposed to 3 to 12 microliters per liter of air of CrO3 and challenged with the virus or bacteria before and after exposure. Some mice were exposed to CrO3 and NO2. Exposure to NO2 caused the production of serum neutralization antibodies within 21 days after virus infection in monkeys. Slight emphysema and thickened bronchial epithelium were observed during histopathological studies. Mortality was enhanced in hamsters infected with bacteria within 1 hour after 5 or 7.5mg NiO, but not with 1 and 10mg. Increased mortality was also noted in virus infected hamsters. Histopathological examination of lung tissue of virus challenged hamsters revealed hyperplastic epithelium, adenomatosis, and thickened pleura. Single or multiple exposure to CrO3 aerosol did not enhance mortality in mice challenged with the bacteria or virus. A combination of CrO3 and NO2 exposure had no effect on mortalities. CrO3 particles were observed in the alveoli and alveolar ducts during histopathological examination./TRANSMISSION"
1237995,Kay 1976,Toxicological Evaluation Of Chemicals Used In The Printing And Printing Inks Industries,"Site visits were made to 25 companies in the printing and printing ink formulation industries. The use of carcinogenic compounds was investigated. A large number of pigments and dyes were in use; however, only a few were used in substantial amounts. Four components of the color compounds were known carcinogens in humans. These were lead-chromate (7758976), lead-chromate/lead molybdate, carbon (7440440), and cadmium-sulfide (1306236). There were 15 components that were probable carcinogens. These were two diazo benzidines, two triaryl methanes, nine mono azodyes, cadmium selenides, and talc (14807966). Solvents of high volatility were used in the formulation of fast drying liquid inks. Toluene (108883) constituted 5 to 62 percent of organic pigment ink. Methyl-ethyl-ketone (78933) was present in inorganic ink at a concentration of 11 percent. Other solvents were used in the cleaning of type faces. The primary solvents for this purpose were methyl-chloroform (71556) and methylene-chloride (75092). Work room atmospheres during newspaper printing were heavily contaminated by dispersed ink. The operation of photo offset machines produced a continuous exposure to ammonia (7664417). Many polymers were used to bind pigments to the printing surface. Plasticizers and oxidation accelerations were used as ink ingredients.","Toxicological Evaluation Of Chemicals Used In The Printing And Printing Inks Industries Abs: Site visits were made to 25 companies in the printing and printing ink formulation industries. The use of carcinogenic compounds was investigated. A large number of pigments and dyes were in use; however, only a few were used in substantial amounts. Four components of the color compounds were known carcinogens in humans. These were lead-chromate (7758976), lead-chromate/lead molybdate, carbon (7440440), and cadmium-sulfide (1306236). There were 15 components that were probable carcinogens. These were two diazo benzidines, two triaryl methanes, nine mono azodyes, cadmium selenides, and talc (14807966). Solvents of high volatility were used in the formulation of fast drying liquid inks. Toluene (108883) constituted 5 to 62 percent of organic pigment ink. Methyl-ethyl-ketone (78933) was present in inorganic ink at a concentration of 11 percent. Other solvents were used in the cleaning of type faces. The primary solvents for this purpose were methyl-chloroform (71556) and methylene-chloride (75092). Work room atmospheres during newspaper printing were heavily contaminated by dispersed ink. The operation of photo offset machines produced a continuous exposure to ammonia (7664417). Many polymers were used to bind pigments to the printing surface. Plasticizers and oxidation accelerations were used as ink ingredients."
1237994,Szarmach et al. 1973,"Chromium, Cobalt And Nickel Contact Allergy Among The Population Of Bialystok Province","Incidence of chromium (7440473), cobalt (7440484), and nickel allergy was studied. Subjects, including bricklayers, concrete workers, ironworkers, machinists, welders, agricultural workers, and housewives, were given skin tests with a 5 percent solution of potassium-dichromate in water and 2 percent solutions of cobalt-sulfate and nickel-sulfate in water. Tests were read at 24, 48, an 72 hours and reactions graded. Among the 1,100 subjects graded, there were 120 positive reactions; many were to more than one metal. The greatest number of monovalent reactions was elicited by chromium, primarily in males. Males were concomitantly sensitive to chromium and cobalt in 15 cases, compared with 9 for females. Females were simultaneously sensitive to cobalt and nickel in 13 cases, contrasted with 8 for males. The sensitivity pattern of agricultural workers did not differ significantly from those of industrial workers. The authors conclude that the similarities between agricultural and industrial patterns of sensitivity reflects increased mechanization and the use of chemical mediums in agriculture. The simultaneous reaction to chromium and cobalt usually occurs in those who might have had occupational exposure. The joint sensitivity to cobalt and nickel occurs in those with a less probable connection between allergy and work. (Polish)","Chromium, Cobalt And Nickel Contact Allergy Among The Population Of Bialystok Province Abs: Incidence of chromium (7440473), cobalt (7440484), and nickel allergy was studied. Subjects, including bricklayers, concrete workers, ironworkers, machinists, welders, agricultural workers, and housewives, were given skin tests with a 5 percent solution of potassium-dichromate in water and 2 percent solutions of cobalt-sulfate and nickel-sulfate in water. Tests were read at 24, 48, an 72 hours and reactions graded. Among the 1,100 subjects graded, there were 120 positive reactions; many were to more than one metal. The greatest number of monovalent reactions was elicited by chromium, primarily in males. Males were concomitantly sensitive to chromium and cobalt in 15 cases, compared with 9 for females. Females were simultaneously sensitive to cobalt and nickel in 13 cases, contrasted with 8 for males. The sensitivity pattern of agricultural workers did not differ significantly from those of industrial workers. The authors conclude that the similarities between agricultural and industrial patterns of sensitivity reflects increased mechanization and the use of chemical mediums in agriculture. The simultaneous reaction to chromium and cobalt usually occurs in those who might have had occupational exposure. The joint sensitivity to cobalt and nickel occurs in those with a less probable connection between allergy and work. (Polish)"
1237992,Ziegler et al. 1973,Fluid Bed Incineration,"The development and testing of a fluid bed incineration process was described. Polyvinyl-chloride (9002862) (PVC) waste was burned in a fluidized bed of sodium-carbonate to neutralize the hydrogen-chloride that was generated during the process. Reactor temperature was set at 500 degrees-C to yield a more soluble, recoverable form of plutonium-oxide (11116033). A catalytic afterburner was used to eliminate the need for refractory lined equipment. The argon or nitrogen fluidization gas contained 10 to 15 percent oxygen to provide bed temperature control and maintain low carbon concentrations in ash. A small, low speed shredder was used to process PVC waste pellets before incineration. Chromic-oxide on alumina was used for the oxidation catalyst. In laboratory tests, more than 90 percent of the hydrogen-chloride was neutralized using this system. This system also was successful for leaded glove incineration. The authors note that a 10 pound per hour pilot fluid bed incineration has been designed for use at actual work sheets.","Fluid Bed Incineration Abs: The development and testing of a fluid bed incineration process was described. Polyvinyl-chloride (9002862) (PVC) waste was burned in a fluidized bed of sodium-carbonate to neutralize the hydrogen-chloride that was generated during the process. Reactor temperature was set at 500 degrees-C to yield a more soluble, recoverable form of plutonium-oxide (11116033). A catalytic afterburner was used to eliminate the need for refractory lined equipment. The argon or nitrogen fluidization gas contained 10 to 15 percent oxygen to provide bed temperature control and maintain low carbon concentrations in ash. A small, low speed shredder was used to process PVC waste pellets before incineration. Chromic-oxide on alumina was used for the oxidation catalyst. In laboratory tests, more than 90 percent of the hydrogen-chloride was neutralized using this system. This system also was successful for leaded glove incineration. The authors note that a 10 pound per hour pilot fluid bed incineration has been designed for use at actual work sheets."
1237991,Anonymous 1973,Epidemiology of Contact Dermatitis in North America: 1972,"Skin sensitivity to 16 allergens was tested in 1200 North Americans from 10 areas. All subjects were suspected of having some type of contact sensitivity. Substances included components of common topical medications, cosmetics, rubber, and preservatives. Patch tests were applied to the skin and read after 48 hours. Results were tabulated and compared to those from a similar European study. At 11 percent, the most common sensitizer was 2.5 percent nickel-sulfate (7786814); reactivity occurred in 4 times as many females as males. This was followed by 8 percent reactivity to 0.5 percent potassium-dichromate (7778509), 0.1 percent thimerosal (54648), and 1 percent p-phenylenediamine (106503); 7 percent reactivity to 1 percent ethylenediamine (107153); and 6 percent reactivity to 20 percent neomycin-sulfate (1405103) and 1 percent turpentine oil. Even the least common sensitizer, 1 percent cyclomethycaine-sulfate (139628), produced reactions in 2 percent of subjects. Differing European results were 6.7 percent reactivity to nickel-sulfate, 3.7 percent reactivity to neomycin-sulfate, and 4.9 percent reactivity to p-phenylenediamine. The authors conclude that this data provides a rational basis for selecting antigens for office or hospital screening series in North America.","Epidemiology of Contact Dermatitis in North America: 1972 Abs: Skin sensitivity to 16 allergens was tested in 1200 North Americans from 10 areas. All subjects were suspected of having some type of contact sensitivity. Substances included components of common topical medications, cosmetics, rubber, and preservatives. Patch tests were applied to the skin and read after 48 hours. Results were tabulated and compared to those from a similar European study. At 11 percent, the most common sensitizer was 2.5 percent nickel-sulfate (7786814); reactivity occurred in 4 times as many females as males. This was followed by 8 percent reactivity to 0.5 percent potassium-dichromate (7778509), 0.1 percent thimerosal (54648), and 1 percent p-phenylenediamine (106503); 7 percent reactivity to 1 percent ethylenediamine (107153); and 6 percent reactivity to 20 percent neomycin-sulfate (1405103) and 1 percent turpentine oil. Even the least common sensitizer, 1 percent cyclomethycaine-sulfate (139628), produced reactions in 2 percent of subjects. Differing European results were 6.7 percent reactivity to nickel-sulfate, 3.7 percent reactivity to neomycin-sulfate, and 4.9 percent reactivity to p-phenylenediamine. The authors conclude that this data provides a rational basis for selecting antigens for office or hospital screening series in North America."
1237989,Vizhkov and  Fedorova 1967,The Blastomogenic Properties of Chromium Oxide,"The blastomogenic activity of chromium-oxide administered into the trachea, pleural slit, and abdominal cavity was studied in rats. Rats received doses of 50, 20 and 10 milligrams of chromium-oxide. Pulmonary sarcomas developed in 22.4 percent of animals, usually 2 years after exposure. Microscopic examination revealed the initial stages of the blastomatous process usually arose in the perivascular and peribronchial reticular lung tissue. Reticulosarcomas and general reticulosarcomatosis developed. Larger doses induced more tumors than smaller doses. The authors conclude that chromium-oxide administered by dust into lungs of rats causes malignant sarcomatous growth. (Russian).","The Blastomogenic Properties of Chromium Oxide Abs: The blastomogenic activity of chromium-oxide administered into the trachea, pleural slit, and abdominal cavity was studied in rats. Rats received doses of 50, 20 and 10 milligrams of chromium-oxide. Pulmonary sarcomas developed in 22.4 percent of animals, usually 2 years after exposure. Microscopic examination revealed the initial stages of the blastomatous process usually arose in the perivascular and peribronchial reticular lung tissue. Reticulosarcomas and general reticulosarcomatosis developed. Larger doses induced more tumors than smaller doses. The authors conclude that chromium-oxide administered by dust into lungs of rats causes malignant sarcomatous growth. (Russian)."
1237988,Andri and  Pendini 1964,Epicutaneous Test Carried Out With Substances Used in the Printing Industry For Prevention of Allergic Dermatoses,Allergic reactions to a wide variety of substances used in the printing industry were evaluated via skin patch tests of 195 printing firm workers employed for 4 to 7 months. Subjects were tested with chemicals that they were exposed to during their particular jobs. Reactions were read at 48 hours. Only 2 slightly positive reactions were found out of 773 skin tests; one to rotogravure printing paints and one to potassium bichromate. The authors conclude that the skin tests cannot be used for diagnostic or prognostic purposes. (Italian).,Epicutaneous Test Carried Out With Substances Used in the Printing Industry For Prevention of Allergic Dermatoses Abs: Allergic reactions to a wide variety of substances used in the printing industry were evaluated via skin patch tests of 195 printing firm workers employed for 4 to 7 months. Subjects were tested with chemicals that they were exposed to during their particular jobs. Reactions were read at 48 hours. Only 2 slightly positive reactions were found out of 773 skin tests; one to rotogravure printing paints and one to potassium bichromate. The authors conclude that the skin tests cannot be used for diagnostic or prognostic purposes. (Italian).
1237987,Brard 1935,Toxicologie du chrome,"The toxicity of chromium (7440473) compounds and their localization in the organs were studied in dogs and rabbits. Animals received various single or repeated doses of potassium-bichromate (7778509) or chromic-chloride (7778509) by oral, subcutaneous or intravenous routes. All animals were observed for clinical signs of poisoning. Autopsies were performed, and chromium concentration in the tissues was assayed. Blood parameters were measured and elimination of chromium in bile, urine, and mucous membranes of stomach and intestine was studied. In acute poisoning, vomiting, digestive tract hemorrhages, diarrhea, extreme prostration, loss of heat from extremities, respiratory impairment, hemorrhagic patches on the lungs, and kidney lesions were seen regardless of route of administration. Chromium was localized in the kidneys, liver, and endocrine glands, particularly the adrenals, thyroid and hypophysis. Chromium was eliminated in the urine, bile, and by mucosae of stomach and intestine. Chromic-chloride was less toxic in acute doses than potassium bichromate. The prolonged daily intake of small amounts of both chromium compounds was clearly toxic. Severe anemia with hyperleukocytosis, pancreatic and renal lesions, pulmonary edema, and finally death occurred. The chromium was localized in nails, hair, teeth, endocrine organs, lymphatic glands and bone marrow. The authors conclude that both trivalent and hexavalent chromium are toxic. (French).","Toxicologie du chrome Abs: The toxicity of chromium (7440473) compounds and their localization in the organs were studied in dogs and rabbits. Animals received various single or repeated doses of potassium-bichromate (7778509) or chromic-chloride (7778509) by oral, subcutaneous or intravenous routes. All animals were observed for clinical signs of poisoning. Autopsies were performed, and chromium concentration in the tissues was assayed. Blood parameters were measured and elimination of chromium in bile, urine, and mucous membranes of stomach and intestine was studied. In acute poisoning, vomiting, digestive tract hemorrhages, diarrhea, extreme prostration, loss of heat from extremities, respiratory impairment, hemorrhagic patches on the lungs, and kidney lesions were seen regardless of route of administration. Chromium was localized in the kidneys, liver, and endocrine glands, particularly the adrenals, thyroid and hypophysis. Chromium was eliminated in the urine, bile, and by mucosae of stomach and intestine. Chromic-chloride was less toxic in acute doses than potassium bichromate. The prolonged daily intake of small amounts of both chromium compounds was clearly toxic. Severe anemia with hyperleukocytosis, pancreatic and renal lesions, pulmonary edema, and finally death occurred. The chromium was localized in nails, hair, teeth, endocrine organs, lymphatic glands and bone marrow. The authors conclude that both trivalent and hexavalent chromium are toxic. (French)."
1237986,Chekunova 1971,Chromium and Its Compounds,"A review of chromium (7440473) (Cr) and its compounds was presented. The physical and chemical properties of Cr, chromic-anhydride (1333820), chromic-oxide (1308389), potassium-chromium-alums (7788990), sodium-chromium-alums (36221655), sodium-bichromate (10588019), and potassium-bichromate (7778509) were reviewed. The toxic effects of chromium compounds, including the general nature of the effect on the body, intoxication, toxic doses in animals and humans, chronic poisoning, effects on the skin in animals and humans, entry into the body, dispersion and elimination, treatment, protective and preventive measures, and detection in the air and body were discussed. (Russian).","Chromium and Its Compounds Abs: A review of chromium (7440473) (Cr) and its compounds was presented. The physical and chemical properties of Cr, chromic-anhydride (1333820), chromic-oxide (1308389), potassium-chromium-alums (7788990), sodium-chromium-alums (36221655), sodium-bichromate (10588019), and potassium-bichromate (7778509) were reviewed. The toxic effects of chromium compounds, including the general nature of the effect on the body, intoxication, toxic doses in animals and humans, chronic poisoning, effects on the skin in animals and humans, entry into the body, dispersion and elimination, treatment, protective and preventive measures, and detection in the air and body were discussed. (Russian)."
1237985,Alekpervov 1965,Experience in the Study of Morbidity Involving the Temporary Disability of Personnel at a Synthetic Rubber Plant,"The morbidity experience of workers in a group of shops which produce divinyl (106990) from the butane-butylene fractions in a synthetic rubber facility was studied. The hazards in the shop included saturated and unsaturated aliphatic hydrocarbons in the air of the basic shops, and chromium compounds and dust in the catalyst shop. The morbidity rate for two years from 1960-1961 was based on primary documents recorded by the employer. Differential indexes of morbidity were used which allowed determinations of the role of occupational industrial factors in the morbidity features of the facility. Temporary disability by shop and job were considered. The morbidity rate, was lowest in the laboratory and catalyst shop and highest in the basic shops. The authors suggest significant difference between catalyst shop and laboratory may be due to the presence of chromium-trioxide and dust in the catalyst shop but not in the laboratory. The author concludes that the morbidity index for all workers in this study was low due to preliminary medical selection of the workers, and the employment of mostly young workers who had limited industrial experience with only brief exposures to harmful occupational conditions. (Russian).","Experience in the Study of Morbidity Involving the Temporary Disability of Personnel at a Synthetic Rubber Plant Abs: The morbidity experience of workers in a group of shops which produce divinyl (106990) from the butane-butylene fractions in a synthetic rubber facility was studied. The hazards in the shop included saturated and unsaturated aliphatic hydrocarbons in the air of the basic shops, and chromium compounds and dust in the catalyst shop. The morbidity rate for two years from 1960-1961 was based on primary documents recorded by the employer. Differential indexes of morbidity were used which allowed determinations of the role of occupational industrial factors in the morbidity features of the facility. Temporary disability by shop and job were considered. The morbidity rate, was lowest in the laboratory and catalyst shop and highest in the basic shops. The authors suggest significant difference between catalyst shop and laboratory may be due to the presence of chromium-trioxide and dust in the catalyst shop but not in the laboratory. The author concludes that the morbidity index for all workers in this study was low due to preliminary medical selection of the workers, and the employment of mostly young workers who had limited industrial experience with only brief exposures to harmful occupational conditions. (Russian)."
1237982,Anonymous 1966,Zinc and Compounds,"Zinc-chloride (7646857) is an irritant to the skin, eyes, nose and throat. Zinc-chromate (1328672), zinc-cyanide (557211) and zinc-sulfate (7733020) may cause dermatitis. Inhalation of zinc-chloride can produce pneumonitis. When zinc (7440666) is heated to close to the boiling point, very finely divided zinc-oxide (1314132) fume is produced; this can produce metal fume fever. The recommended threshold limit for zinc-oxide fume is 5 milligrams per cubic meter of air. Potential occupational exposures to zinc and its compounds are listed separately.","Zinc and Compounds Abs: Zinc-chloride (7646857) is an irritant to the skin, eyes, nose and throat. Zinc-chromate (1328672), zinc-cyanide (557211) and zinc-sulfate (7733020) may cause dermatitis. Inhalation of zinc-chloride can produce pneumonitis. When zinc (7440666) is heated to close to the boiling point, very finely divided zinc-oxide (1314132) fume is produced; this can produce metal fume fever. The recommended threshold limit for zinc-oxide fume is 5 milligrams per cubic meter of air. Potential occupational exposures to zinc and its compounds are listed separately."
1237981,Anonymous 1952,Determination of Vanadium in Ferro-Vanadium,"The analysis of ferrovanadium (1336169) was studied as part of an investigation of the determination of vanadium (7440622) in ferrous materials. Various techniques for the formation of pentavalent vanadium in sulfuric-acid solution have been compared and the method finally recommended is described. This recommended method includes oxidation with permanganate, the excess being reduced by sodium-nitrite/sulfamic-acid treatment, and titration of the pentavalent vanadium with standard ferrous ammonium-sulfate solution. Exact balance to the change-point of barium diphenylamine-sulfonate indicator is achieved with standard potassium dichromate.","Determination of Vanadium in Ferro-Vanadium Abs: The analysis of ferrovanadium (1336169) was studied as part of an investigation of the determination of vanadium (7440622) in ferrous materials. Various techniques for the formation of pentavalent vanadium in sulfuric-acid solution have been compared and the method finally recommended is described. This recommended method includes oxidation with permanganate, the excess being reduced by sodium-nitrite/sulfamic-acid treatment, and titration of the pentavalent vanadium with standard ferrous ammonium-sulfate solution. Exact balance to the change-point of barium diphenylamine-sulfonate indicator is achieved with standard potassium dichromate."
1237980,Olkhovskaya 1971,"Colorimetric Method for Assaying the Hydrocarbons, Benzene, Kerosene, and White Spirit in the Air of Industrial Installations","A colorimetric method is presented for assaying the hydrocarbons benzene, kerosene (8008206), and white-spirit (8030306) in the air of industrial installations. The principle of the method is described as follows. When the hydrocarbons react with a 0.01 percent solution of potassium bichromate in concentrated sulfuric-acid, soluble substances having a light yellow to a dark cinnamon color are formed as a result of the oxidation. The intensity of the color reaction depends on the concentration of hydrocarbons. The content of these compounds is determined by the degree of color change as read on a standard scale. The sensitivity of the method for benzene (71432) is 0.05 milligram in 3 milliliters; for kerosene it is 0.02 milligram in 3 milliliters and for white spirit, 0.025 milligram in 3 milliliters. (Russian; English translation available)","Colorimetric Method for Assaying the Hydrocarbons, Benzene, Kerosene, and White Spirit in the Air of Industrial Installations Abs: A colorimetric method is presented for assaying the hydrocarbons benzene, kerosene (8008206), and white-spirit (8030306) in the air of industrial installations. The principle of the method is described as follows. When the hydrocarbons react with a 0.01 percent solution of potassium bichromate in concentrated sulfuric-acid, soluble substances having a light yellow to a dark cinnamon color are formed as a result of the oxidation. The intensity of the color reaction depends on the concentration of hydrocarbons. The content of these compounds is determined by the degree of color change as read on a standard scale. The sensitivity of the method for benzene (71432) is 0.05 milligram in 3 milliliters; for kerosene it is 0.02 milligram in 3 milliliters and for white spirit, 0.025 milligram in 3 milliliters. (Russian; English translation available)"
1237977,Anonymous 1968,Rat Pellet Studies with Chromium Compounds,"Rat pellet studies with calcium chromate resulted in 8 lung cancers in an exposed group of 100 animals, including 6 lung squamous cell carcinomas, and 2 lung adenocarcinomas. Chromic chromate was responsible for the induction of one hepatocellular carcinoma metastatic to the lung, chromic-trioxide (1333820) induced 2 hepatocellular carcinomas, and chromate process residue was responsible for the onset of one hepatocellular carcinoma. With the exception of chromic-trioxide, all the other experimental groups showed atypical squamous metaplasia of the bronchus.","Rat Pellet Studies with Chromium Compounds Abs: Rat pellet studies with calcium chromate resulted in 8 lung cancers in an exposed group of 100 animals, including 6 lung squamous cell carcinomas, and 2 lung adenocarcinomas. Chromic chromate was responsible for the induction of one hepatocellular carcinoma metastatic to the lung, chromic-trioxide (1333820) induced 2 hepatocellular carcinomas, and chromate process residue was responsible for the onset of one hepatocellular carcinoma. With the exception of chromic-trioxide, all the other experimental groups showed atypical squamous metaplasia of the bronchus."
1237971,Laskin 1968,"Research in Environmental Health and Cancer: Fourth Annual Report of Progress, USPHS Core Grant: ES 00260","Progress report of chemical carcinogenesis, including intrabronchial pellet studies with carcinogens, chromium compounds and polyester-fiberglass dust, in the rat; hamster endotracheal intubations with carcinogens and polyester-fiberglass dust; inhalation studies with fiberglass dust, polyurethane dust, and chlorinated alkyl ethers; and combined carcinogen and sulfur-dioxide inhalation exposures. Rat pellet studies with calcium chromate resulted in 8 lung cancers in an exposed group of 100 animals, including 6 squamous cell carcinomas and 2 adenocarcinomas. Chromic chromate was responsible for the induction of one hepatocellular carcinoma metastatic to the lung, while chromic-trioxide (1333820) induced 2 hepatocellular carcinomas, and chromate process residue was responsible for the onset of one hepatocellular carcinoma. With the exception of chromic-trioxide, all the other experimental groups showed atypical squamous metaplasia of the bronchus.","Research in Environmental Health and Cancer: Fourth Annual Report of Progress, USPHS Core Grant: ES 00260 Abs: Progress report of chemical carcinogenesis, including intrabronchial pellet studies with carcinogens, chromium compounds and polyester-fiberglass dust, in the rat; hamster endotracheal intubations with carcinogens and polyester-fiberglass dust; inhalation studies with fiberglass dust, polyurethane dust, and chlorinated alkyl ethers; and combined carcinogen and sulfur-dioxide inhalation exposures. Rat pellet studies with calcium chromate resulted in 8 lung cancers in an exposed group of 100 animals, including 6 squamous cell carcinomas and 2 adenocarcinomas. Chromic chromate was responsible for the induction of one hepatocellular carcinoma metastatic to the lung, while chromic-trioxide (1333820) induced 2 hepatocellular carcinomas, and chromate process residue was responsible for the onset of one hepatocellular carcinoma. With the exception of chromic-trioxide, all the other experimental groups showed atypical squamous metaplasia of the bronchus."
1237968,Gross et al. 1943,Lung Cancer in the Chromate Dye Industry,"The case histories are described of 8 workers who developed lung cancer following 5-16 years of employment in the manufacturing of chromate dyes, lead-chromate (7758976) and zinc chromate. The occurrence of lung cancer is attributed to the inhalation of chromate dust. Control measures are recommended for preventing the formation and inhalation of chromate dust. (German: English translation available).","Lung Cancer in the Chromate Dye Industry Abs: The case histories are described of 8 workers who developed lung cancer following 5-16 years of employment in the manufacturing of chromate dyes, lead-chromate (7758976) and zinc chromate. The occurrence of lung cancer is attributed to the inhalation of chromate dust. Control measures are recommended for preventing the formation and inhalation of chromate dust. (German: English translation available)."
1237965,Cumin 1927,Remarks on the Medicinal Properties of Madar and on the Effects of Bichromate of Potass on the Human Body,"The therapeutic value of madar powder and of potassium-bichromate are discussed. The effect of potassium-bichromate (7778509) exposure on the skin of dyers is described. It produced an eruption of papule, which become pustular after a short time and caused deep sloughs to form under the pustules, after continued exposure. Differences were shown to exist in the susceptibility of individuals to this reaction.","Remarks on the Medicinal Properties of Madar and on the Effects of Bichromate of Potass on the Human Body Abs: The therapeutic value of madar powder and of potassium-bichromate are discussed. The effect of potassium-bichromate (7778509) exposure on the skin of dyers is described. It produced an eruption of papule, which become pustular after a short time and caused deep sloughs to form under the pustules, after continued exposure. Differences were shown to exist in the susceptibility of individuals to this reaction."
1237963,Jaeger and  Pelloni 1950,"Skin Test to Bichromates, Positive with Cement Eczema","Skin tests with potassium-bichromate (7778509) were used to study subjects with cement eczema. The skin test with a 1/2 percent aqueous solution of potassium-bichromate proved to be positive in the great majority of cement eczemas and negative in other eczemas. The positive reaction to potassium-bichromate was, from the chemical point of view, tied to the chromium (7440473) and not to the potassium (7440097). Cement eczema appears to be, in reality, chromium salts eczema. The chemical analysis of different cements revealed the unsuspected presence of chromium, in the state of chromate, in small but non-negligible quantities. Chromium was found in the marls used for manufacture.","Skin Test to Bichromates, Positive with Cement Eczema Abs: Skin tests with potassium-bichromate (7778509) were used to study subjects with cement eczema. The skin test with a 1/2 percent aqueous solution of potassium-bichromate proved to be positive in the great majority of cement eczemas and negative in other eczemas. The positive reaction to potassium-bichromate was, from the chemical point of view, tied to the chromium (7440473) and not to the potassium (7440097). Cement eczema appears to be, in reality, chromium salts eczema. The chemical analysis of different cements revealed the unsuspected presence of chromium, in the state of chromate, in small but non-negligible quantities. Chromium was found in the marls used for manufacture."
1237961,Laskin 1968,Carcinogenesis Studies with Chromium Compounds,"A partial report on the progress made in the research on cancer resulting from chromium (7440473) compounds. Studies with the intrabronchial pellet technique in rats show the production of squamous cell carcinomas with calcium-chromate. Hepato cell carcinomas are produced with chromic chromate, chromic-trioxide, and process residue that is an industrial intermediate.","Carcinogenesis Studies with Chromium Compounds Abs: A partial report on the progress made in the research on cancer resulting from chromium (7440473) compounds. Studies with the intrabronchial pellet technique in rats show the production of squamous cell carcinomas with calcium-chromate. Hepato cell carcinomas are produced with chromic chromate, chromic-trioxide, and process residue that is an industrial intermediate."
1237959,Cralley et al. 1943,Modification of the Silica Gel Method for the Determination of Atmospheric Organic Solvent Vapors,A general method is presented for the determination of atmospheric organic solvent vapors. In this procedure the organic vapor is adsorbed by silica gel and is then removed from the gel by a second solvent which will not cause subsequent interference. The amount of the organic solvent in question is then determined by any acceptable method of quantitative chemical analysis. Carbon-tetrachloride (56235) was removed from the silica gel by ethyl-alcohol (64175) and decomposed by alcoholic potassium-hydroxide (1310583). The amount of chloride formed was determined volumetrically by silver-nitrate (7761888) in which potassium-chromate (7789006) served as the indicator. The procedure described has been found to be suitable for the determination of carbon-tetrachloride in the air in concentrations of hygienic importance.,Modification of the Silica Gel Method for the Determination of Atmospheric Organic Solvent Vapors Abs: A general method is presented for the determination of atmospheric organic solvent vapors. In this procedure the organic vapor is adsorbed by silica gel and is then removed from the gel by a second solvent which will not cause subsequent interference. The amount of the organic solvent in question is then determined by any acceptable method of quantitative chemical analysis. Carbon-tetrachloride (56235) was removed from the silica gel by ethyl-alcohol (64175) and decomposed by alcoholic potassium-hydroxide (1310583). The amount of chloride formed was determined volumetrically by silver-nitrate (7761888) in which potassium-chromate (7789006) served as the indicator. The procedure described has been found to be suitable for the determination of carbon-tetrachloride in the air in concentrations of hygienic importance.
1237958,Williams and  Reese 1950,Colorimetric Determination of Ethyl Alcohol,"A simple, accurate spectrophotometric method is described for the determination of 0.0010 to 5.800 milligrams of ethyl-alcohol per milliliter in aqueous solution. The procedure is based on the quantitative oxidation of ethyl-alcohol (64175) by a potassium-dichromate sulfuric-acid (7664939) reagent and dilution of the resulting solution to a concentration where the chromic ions will not interfere with the violet-colored complex developed with the excess dichromate (13907476) when s-diphenylcarbazide (140227) is added. This complex follows Beer's law accurately at 540 millimicrons. This is a reference in the Isopropyl-Alcohol (67630) Criteria Document.","Colorimetric Determination of Ethyl Alcohol Abs: A simple, accurate spectrophotometric method is described for the determination of 0.0010 to 5.800 milligrams of ethyl-alcohol per milliliter in aqueous solution. The procedure is based on the quantitative oxidation of ethyl-alcohol (64175) by a potassium-dichromate sulfuric-acid (7664939) reagent and dilution of the resulting solution to a concentration where the chromic ions will not interfere with the violet-colored complex developed with the excess dichromate (13907476) when s-diphenylcarbazide (140227) is added. This complex follows Beer's law accurately at 540 millimicrons. This is a reference in the Isopropyl-Alcohol (67630) Criteria Document."
1237957,Anonymous 1940,The Relative Toxicity of Lead and Some of Its Common Compounds,"An experimental inquiry was conducted regarding the relative toxicity of lead (7439921) and various commonly encountered lead compounds. More than 500 guinea-pigs were studied during and following administration of the substances by mouth, by intraperitoneal injection, and by inhalation. Symptoms of lead poisoning such as muscular incoordination and anemia were sought, blood changes, polychromasia, and morphologic changes were noted, and blood calcium determinations were made. Body weight changes and mortality figures were collected. The lead compound was administered in measured amounts in ingestion and intraperitoneal experiments, and the degree of exposure in inhalation experiments was determined by sampling and analyzing the dusty air for lead at intervals during exposure. Finally, lead was traced out in various tissues and analytical determinations were made of amounts present in the liver, kidney, and bones in order to determine the degree of absorption that had occurred. In the inhalation experiments, determinations of the lead content of the lungs were also made. Particle size determinations were made of suspended lead fume or dust, and identification of dust particles in-situ in lung tissue was established in the case of animals exposed to lead by inhalation. The toxic effect of lead compounds was more evident on inhalation than when administered by other routes, and this result emphasizes the importance of this type of industrial exposure. Lead-arsenate (7645252) proved to be extremely toxic on intraperitoneal injection in comparison with other compounds tested. The order of toxicity as shown by feeding experiments did not vary much for a number of compounds studied. However, lead-carbonate, lead-monoxide, and lead-sulfate (7446142) were more toxic by mouth than lead or the remaining lead compounds. Lead-carbonate (598630) and lead-monoxide (1317368) were more toxic after inhalation than the other compounds studied. Other lead compounds mentioned include lead-chromate (1308298), lead-dioxide (1309600), lead-phosphate (7446277), lead-silicate (10099760), lead-sulfide (1314870), and red-lead (1314416).","The Relative Toxicity of Lead and Some of Its Common Compounds Abs: An experimental inquiry was conducted regarding the relative toxicity of lead (7439921) and various commonly encountered lead compounds. More than 500 guinea-pigs were studied during and following administration of the substances by mouth, by intraperitoneal injection, and by inhalation. Symptoms of lead poisoning such as muscular incoordination and anemia were sought, blood changes, polychromasia, and morphologic changes were noted, and blood calcium determinations were made. Body weight changes and mortality figures were collected. The lead compound was administered in measured amounts in ingestion and intraperitoneal experiments, and the degree of exposure in inhalation experiments was determined by sampling and analyzing the dusty air for lead at intervals during exposure. Finally, lead was traced out in various tissues and analytical determinations were made of amounts present in the liver, kidney, and bones in order to determine the degree of absorption that had occurred. In the inhalation experiments, determinations of the lead content of the lungs were also made. Particle size determinations were made of suspended lead fume or dust, and identification of dust particles in-situ in lung tissue was established in the case of animals exposed to lead by inhalation. The toxic effect of lead compounds was more evident on inhalation than when administered by other routes, and this result emphasizes the importance of this type of industrial exposure. Lead-arsenate (7645252) proved to be extremely toxic on intraperitoneal injection in comparison with other compounds tested. The order of toxicity as shown by feeding experiments did not vary much for a number of compounds studied. However, lead-carbonate, lead-monoxide, and lead-sulfate (7446142) were more toxic by mouth than lead or the remaining lead compounds. Lead-carbonate (598630) and lead-monoxide (1317368) were more toxic after inhalation than the other compounds studied. Other lead compounds mentioned include lead-chromate (1308298), lead-dioxide (1309600), lead-phosphate (7446277), lead-silicate (10099760), lead-sulfide (1314870), and red-lead (1314416)."
1237956,Anonymous 1938,Sulphur Dioxide,"Methods for the chemical detection of small amounts of sulfur-dioxide (7446095) in the atmosphere of the workplace were described. The methods included the use of test papers impregnated with starch potassium-iodate with and without the addition of potassium-iodide, potassium-chromate or dichromate papers, or potassium-ferricyanide/ferric-chloride. Limitations of each method were discussed with regard to relevance and cost effectiveness for the work site. The starch potassium-iodate potassium-iodide glycerol test paper reaction was selected as the standard method for estimating sulfur-dioxide vapors in the work environment. The atmosphere was sampled using a hand exhausting pump calibrated on the basis of number of strokes producing color intensities equal to known sulfur-dioxide concentrations. The pump was used to draw the sample air through the test paper, and stains obtained on the side of the paper exposed to the gas entering the pump were compared with a standard chart. The poisonous effects of sulfur-dioxide vapors and first aid in the case of accidental gassing were described.","Sulphur Dioxide Abs: Methods for the chemical detection of small amounts of sulfur-dioxide (7446095) in the atmosphere of the workplace were described. The methods included the use of test papers impregnated with starch potassium-iodate with and without the addition of potassium-iodide, potassium-chromate or dichromate papers, or potassium-ferricyanide/ferric-chloride. Limitations of each method were discussed with regard to relevance and cost effectiveness for the work site. The starch potassium-iodate potassium-iodide glycerol test paper reaction was selected as the standard method for estimating sulfur-dioxide vapors in the work environment. The atmosphere was sampled using a hand exhausting pump calibrated on the basis of number of strokes producing color intensities equal to known sulfur-dioxide concentrations. The pump was used to draw the sample air through the test paper, and stains obtained on the side of the paper exposed to the gas entering the pump were compared with a standard chart. The poisonous effects of sulfur-dioxide vapors and first aid in the case of accidental gassing were described."
1237955,Stemmer 1971,Biological Effects of Chromium and Ferrochrome Alloys,Results are presented of a research program regarding the biological effects of trivalent chromium (7440473) and ferrochrome alloys. The following topics were investigated: solubility of trivalent chromium dust; interaction of chromium with human protein; transport of chromium by different types of tissues; subcellular distribution of chromium; exposure system for inhalation of chromium-oxide; pulmonary effects of chromium-oxide; pulmonary cell separation; and effect of suboptimal intake of chromium.,Biological Effects of Chromium and Ferrochrome Alloys Abs: Results are presented of a research program regarding the biological effects of trivalent chromium (7440473) and ferrochrome alloys. The following topics were investigated: solubility of trivalent chromium dust; interaction of chromium with human protein; transport of chromium by different types of tissues; subcellular distribution of chromium; exposure system for inhalation of chromium-oxide; pulmonary effects of chromium-oxide; pulmonary cell separation; and effect of suboptimal intake of chromium.
1237952,Lemyasev 1964,The Significance Of The Dust Factor In The Overhauling Of Open-Hearth Furnaces,"The amount of dust present in the overhauling of open hearth furnaces, and the effect of that dust on workers, was investigated. The dust content of air at three different facilities was determined by the gravimetric method. Various areas within each facility were subjected to the recording. Respiratory indices were assessed for workers in the areas. Dust concentrations were high in three different areas: tearing down the checkered brickwork; cleaning the horizontal flues; and tearing down the furnace hearth walls. Dust contained free silica, magnesium-oxide (1309484), ferric-oxide (1309371), calcium-oxide (1305788), and chromium-oxide (11118573). Pulmonary ventilation and respiratory rates of workers varied according to the intensity of the work being done. Respiratory rates increased with increasing intensity of work. Along with the increase in respiratory rate and increase in respiratory minute volume, there was also an increase in depth of inspiration. The author concludes that the large volume of dust laden air passing through the lungs contributes to an increase in the intake and deposition of dust in the lungs. (Russian)","The Significance Of The Dust Factor In The Overhauling Of Open-Hearth Furnaces Abs: The amount of dust present in the overhauling of open hearth furnaces, and the effect of that dust on workers, was investigated. The dust content of air at three different facilities was determined by the gravimetric method. Various areas within each facility were subjected to the recording. Respiratory indices were assessed for workers in the areas. Dust concentrations were high in three different areas: tearing down the checkered brickwork; cleaning the horizontal flues; and tearing down the furnace hearth walls. Dust contained free silica, magnesium-oxide (1309484), ferric-oxide (1309371), calcium-oxide (1305788), and chromium-oxide (11118573). Pulmonary ventilation and respiratory rates of workers varied according to the intensity of the work being done. Respiratory rates increased with increasing intensity of work. Along with the increase in respiratory rate and increase in respiratory minute volume, there was also an increase in depth of inspiration. The author concludes that the large volume of dust laden air passing through the lungs contributes to an increase in the intake and deposition of dust in the lungs. (Russian)"
1237951,Anonymous 1958,Industrial Cancer,"Data concerning cancer induction by exposure to industrial agents is reviewed. An investigation carried out at six dichromate factories in the United States during 1947 revealed that 21.82 percent of all worker deaths observed were due to cancer of the respiratory system, especially of the lungs, this figure being 16 times the expected ratio. Lung cancer has also been reported among German workers engaged in the manufacture of zinc-chromate (13530659) and lead-chromate (7758976) for use as pigments. Cases of lung cancer induced by asbestos (1332214) among workers suffering from silicosis have been reported in the United States, England, and Germany. Other carcinogenic agents which are likely to increase the number of deaths due to cancer in India over the next 15 to 30 years include sodium-dichromate (10588019), potassium-dichromate (7778509), beta-naphthylamine (91598), benzidine (91598), and the radioactive ores used in the production of atomic energy. The author concludes that no definite cases of cancer attributable to human contact with a carcinogen on the job have been reported in India to date. It is recommended that the medical profession cooperate with management, labor, and the government in order to cope with the growing menace of occupational cancer in India.","Industrial Cancer Abs: Data concerning cancer induction by exposure to industrial agents is reviewed. An investigation carried out at six dichromate factories in the United States during 1947 revealed that 21.82 percent of all worker deaths observed were due to cancer of the respiratory system, especially of the lungs, this figure being 16 times the expected ratio. Lung cancer has also been reported among German workers engaged in the manufacture of zinc-chromate (13530659) and lead-chromate (7758976) for use as pigments. Cases of lung cancer induced by asbestos (1332214) among workers suffering from silicosis have been reported in the United States, England, and Germany. Other carcinogenic agents which are likely to increase the number of deaths due to cancer in India over the next 15 to 30 years include sodium-dichromate (10588019), potassium-dichromate (7778509), beta-naphthylamine (91598), benzidine (91598), and the radioactive ores used in the production of atomic energy. The author concludes that no definite cases of cancer attributable to human contact with a carcinogen on the job have been reported in India to date. It is recommended that the medical profession cooperate with management, labor, and the government in order to cope with the growing menace of occupational cancer in India."
1237944,Rudzki et al. 1971,Cobalt Allergy As The Reason Of Professional Eczema,"The effects of cobalt (7440484), chromium (7440473), and nickel (7440020) exposure on allergic eczema were studied in humans. A total of 105 patients with skin allergies to cobalt and 104 patients with chromium skin allergies were selected from among 690 allergic skin disorders. The subjects were administered skin tests with solutions of potassium-dichromate (7778509), nickel-sulfate (7786814), or cobalt, compound not specified. The incidence of positive responses among individuals with cobalt allergies was determined. Attempts were made to correlate the incidence of cobalt skin allergies with age and occupation. Allergy to cobalt occurred in 33.3 percent of the tested subjects. Combined cobalt and chromium allergy was found in 31.4 percent and combined cobalt and nickel allergy was found in 14.4 percent of the subjects. The highest incidence of cobalt allergy occurred among subjects over 40 years old. The highest incidence of cobalt allergy occurred in construction workers, followed by photographers and printers, ceramic industry workers, rubber and plastics workers, electrochemical workers, leather workers, and varnish and paint workers in that order. The authors conclude that cobalt allergy is associated with chromium allergy more than with nickel allergy. When chromium allergy is suspected, the patients should also be tested for cobalt allergy. (Polish)","Cobalt Allergy As The Reason Of Professional Eczema Abs: The effects of cobalt (7440484), chromium (7440473), and nickel (7440020) exposure on allergic eczema were studied in humans. A total of 105 patients with skin allergies to cobalt and 104 patients with chromium skin allergies were selected from among 690 allergic skin disorders. The subjects were administered skin tests with solutions of potassium-dichromate (7778509), nickel-sulfate (7786814), or cobalt, compound not specified. The incidence of positive responses among individuals with cobalt allergies was determined. Attempts were made to correlate the incidence of cobalt skin allergies with age and occupation. Allergy to cobalt occurred in 33.3 percent of the tested subjects. Combined cobalt and chromium allergy was found in 31.4 percent and combined cobalt and nickel allergy was found in 14.4 percent of the subjects. The highest incidence of cobalt allergy occurred among subjects over 40 years old. The highest incidence of cobalt allergy occurred in construction workers, followed by photographers and printers, ceramic industry workers, rubber and plastics workers, electrochemical workers, leather workers, and varnish and paint workers in that order. The authors conclude that cobalt allergy is associated with chromium allergy more than with nickel allergy. When chromium allergy is suspected, the patients should also be tested for cobalt allergy. (Polish)"
1237943,Wutzdorff 1997,Damage To Health Observed In Chromate Plants And Measures Necessary For Its Prevention,"Health damage incurred in chromate (11104599) factories is reviewed. Workers with potassium-bichromate (7778509) suffer hand and nasal ulcerations. Tonsils and pharyngeal mucosa of workers who breath chromate vapors or dust exhibit ulcerations; respiratory problems, such as asthma, develop in some workers. In one Russian factory, 50 percent of the workers were reported to suffer destruction of the nasal septum. Lesions are described as round, greyish yellow, and slow to heal. Sick leave among workers at chromate factories is somewhat greater than in other industrial factories. Workers in some factories who use wet cloths over their mouths do not suffer from as many respiratory problems. During various melting processes to produce sodium (7440235) and potassium-bichromate, chromate vapors are produced in large quantities. Several measures are suggested for preventing health damage to workers. Closed containers for the transport of the initial melt to other parts of the factory and wetting down the dust are two simple measures. Separate rooms for drying, screening, chopping, and packaging operations are recommended. The furnace areas are advised to be well ventilated to prevent trapping of vapors. It is also recommended that workers be under medical surveillance, be issued work clothes, and shower after work. (German)","Damage To Health Observed In Chromate Plants And Measures Necessary For Its Prevention Abs: Health damage incurred in chromate (11104599) factories is reviewed. Workers with potassium-bichromate (7778509) suffer hand and nasal ulcerations. Tonsils and pharyngeal mucosa of workers who breath chromate vapors or dust exhibit ulcerations; respiratory problems, such as asthma, develop in some workers. In one Russian factory, 50 percent of the workers were reported to suffer destruction of the nasal septum. Lesions are described as round, greyish yellow, and slow to heal. Sick leave among workers at chromate factories is somewhat greater than in other industrial factories. Workers in some factories who use wet cloths over their mouths do not suffer from as many respiratory problems. During various melting processes to produce sodium (7440235) and potassium-bichromate, chromate vapors are produced in large quantities. Several measures are suggested for preventing health damage to workers. Closed containers for the transport of the initial melt to other parts of the factory and wetting down the dust are two simple measures. Separate rooms for drying, screening, chopping, and packaging operations are recommended. The furnace areas are advised to be well ventilated to prevent trapping of vapors. It is also recommended that workers be under medical surveillance, be issued work clothes, and shower after work. (German)"
1237941,Fregert and  Skog 1962,Allergic Contact Dermatitis From Mercaptobenzothiazole In Cutting Oil,"Allergic contact dermatitis resulting from exposure to 2-mercaptobenzothiazole (149304) (MBT) in a cutting oil was described. Twelve of 25 workers who used a cutting oil for preventing metal corrosion developed dermatitis on the hands or arms 3 to 8 months after initial exposure. The patients were administered patch tests with a 1:50 dilution of the cutting oil. All but one of the patients showed negative reactions to the oil. The patients were then administered patch tests with MBT, 1 percent in petrolatum, and other ingredients of the cutting oil. They were also tested with 0.5 percent potassium-dichromate (7778509), 5 percent nickel-sulfate (7786814), 0.2 percent mercury-nitrate (10415755), 2 percent p-phenylene-diamine (106503), 10 percent turpentine, and 2 percent formaldehyde (50000). Seven of the patients showed positive reactions to MBT. None of the patients reacted to any of the other substances. The MBT containing cutting oil was substituted by another oil that did not contain the substance. This resulted in the disappearance of the dermatitis. The authors conclude that the contact dermatitis in the seven patients had an obvious connection with exposure to the cutting oil containing MBT. Sensitization is facilitated by the primary irritant effect of the oil. In skin testing, it is important to test not only with the commercial product, but also with its ingredients.","Allergic Contact Dermatitis From Mercaptobenzothiazole In Cutting Oil Abs: Allergic contact dermatitis resulting from exposure to 2-mercaptobenzothiazole (149304) (MBT) in a cutting oil was described. Twelve of 25 workers who used a cutting oil for preventing metal corrosion developed dermatitis on the hands or arms 3 to 8 months after initial exposure. The patients were administered patch tests with a 1:50 dilution of the cutting oil. All but one of the patients showed negative reactions to the oil. The patients were then administered patch tests with MBT, 1 percent in petrolatum, and other ingredients of the cutting oil. They were also tested with 0.5 percent potassium-dichromate (7778509), 5 percent nickel-sulfate (7786814), 0.2 percent mercury-nitrate (10415755), 2 percent p-phenylene-diamine (106503), 10 percent turpentine, and 2 percent formaldehyde (50000). Seven of the patients showed positive reactions to MBT. None of the patients reacted to any of the other substances. The MBT containing cutting oil was substituted by another oil that did not contain the substance. This resulted in the disappearance of the dermatitis. The authors conclude that the contact dermatitis in the seven patients had an obvious connection with exposure to the cutting oil containing MBT. Sensitization is facilitated by the primary irritant effect of the oil. In skin testing, it is important to test not only with the commercial product, but also with its ingredients."
1237940,Robin 1969,Etiology And Pathogenesis Of Cement Dermatitis,"The causes and pathogenesis of cement dermatitis were investigated in an effort to find a suitable detection method for eliminating the occupational disease. A total of 178 patients affected by dermatitis were involved in the study. Characteristic symptoms were noted and the patients underwent several patch tests. Physical and biological measurements such as hand thickness, pH, and latex histamine were taken in several cases. All of the workers showed edemas, heat sensations, and dampness of the skin. Others showed color changes, callosities, and cracked skin. The allergological examination showed that 66 percent of the subjects reacted positively to potassium-bichromate (7778509). Also, 18 percent of the patients were allergic to cobalt-sulfate (10124433), and 3 percent to nickel-sulfate (7786814). The cement tests were positive in 24 percent of the subjects. The skin pH was lower in the cement dermatitis patients than in healthy patients. There was no significant difference in hand thickness between the two groups. The latex histamine test was normal in 60 percent of the dermatitis cases. The globular counts and blood counts were also normal. Chromium (7440473) was present on the hands of all subjects who worked with cement. The author concludes that in order to eliminate the disease, strict guidelines should be established to permit the comparison of research results. (French)","Etiology And Pathogenesis Of Cement Dermatitis Abs: The causes and pathogenesis of cement dermatitis were investigated in an effort to find a suitable detection method for eliminating the occupational disease. A total of 178 patients affected by dermatitis were involved in the study. Characteristic symptoms were noted and the patients underwent several patch tests. Physical and biological measurements such as hand thickness, pH, and latex histamine were taken in several cases. All of the workers showed edemas, heat sensations, and dampness of the skin. Others showed color changes, callosities, and cracked skin. The allergological examination showed that 66 percent of the subjects reacted positively to potassium-bichromate (7778509). Also, 18 percent of the patients were allergic to cobalt-sulfate (10124433), and 3 percent to nickel-sulfate (7786814). The cement tests were positive in 24 percent of the subjects. The skin pH was lower in the cement dermatitis patients than in healthy patients. There was no significant difference in hand thickness between the two groups. The latex histamine test was normal in 60 percent of the dermatitis cases. The globular counts and blood counts were also normal. Chromium (7440473) was present on the hands of all subjects who worked with cement. The author concludes that in order to eliminate the disease, strict guidelines should be established to permit the comparison of research results. (French)"
1237938,Rabeau and  Ukrainczyk 1939,"Dermatitis In ""Laundresses"". The Effect Of Chromium And Chlorine (In France)","The causes of dermatitis in laundry workers (SIC-7219) in France were investigated. The frequency of allergic sensitization reactions of the skin reported in the literature were reviewed to identify possible irritant substances. The results of a test using a pure bleach and disinfectant mixture (Javel) and a 10 percent solution of Javel in water were compared in a single patient and then replicated in a group of laundresses, chamber maids, and hotel employees having dermatitis. An investigation of the contents of Javel produced by several manufacturers in France was conducted to identify irritant substances contained in it. A test using the pure Javel was found to be positive within 24 hours, while the results of the 10 percent solution failed to yield a positive result in more than 1500 patients. The test also produced positive results with bichromates in the individuals who were sensitive to the pure Javel. Potassium-bichromate (7778509) was regularly added to Javel as a stabilizer and colorant. Chlorine (7782505) was also found as an irritant present in Javel. Two hundred cases were noted that showed dual intolerance to chlorine and chromium (7440473), and the majority of these subjects had a history of contact with the mixture. The authors conclude that the so called laundress dermatitis common in France is the result of a dual intolerance to chromium and chlorine present in pure Javel. The use of chromium as a stabilizer in commonly used cleaning products should be banned. (French)","Dermatitis In ""Laundresses"". The Effect Of Chromium And Chlorine (In France) Abs: The causes of dermatitis in laundry workers (SIC-7219) in France were investigated. The frequency of allergic sensitization reactions of the skin reported in the literature were reviewed to identify possible irritant substances. The results of a test using a pure bleach and disinfectant mixture (Javel) and a 10 percent solution of Javel in water were compared in a single patient and then replicated in a group of laundresses, chamber maids, and hotel employees having dermatitis. An investigation of the contents of Javel produced by several manufacturers in France was conducted to identify irritant substances contained in it. A test using the pure Javel was found to be positive within 24 hours, while the results of the 10 percent solution failed to yield a positive result in more than 1500 patients. The test also produced positive results with bichromates in the individuals who were sensitive to the pure Javel. Potassium-bichromate (7778509) was regularly added to Javel as a stabilizer and colorant. Chlorine (7782505) was also found as an irritant present in Javel. Two hundred cases were noted that showed dual intolerance to chlorine and chromium (7440473), and the majority of these subjects had a history of contact with the mixture. The authors conclude that the so called laundress dermatitis common in France is the result of a dual intolerance to chromium and chlorine present in pure Javel. The use of chromium as a stabilizer in commonly used cleaning products should be banned. (French)"
1237937,Mosinger and  Fiorentini 1955,Additional experimental findings To the concept of gastric ulcer frequency among chromium workers,"The toxicity of potassium-chromate (7789006) (PC) was studied in guinea-pigs, rats, and rabbits. The animals were administered PC orally, subcutaneously, intraperitoneally, or topically as an ointment containing 1 percent of the compound. The animals were also exposed to an aerosol containing 1 to 2 percent PC. The length of exposure ranged from less than 1 month in the acute and subacute studies to 1 year in the chronic studies. Gross and histopathological examinations were conducted at the end of the experiments. Acute exposure to PC caused superficial ulcerations of the gastric mucosa. Hemorrhagic foci were seen in the stomachs of animals administered PC by the oral, subcutaneous, and intraperitoneal routes. Ulcerative lesions were seen frequently in the small intestine. These were characterized by small superficial ulcerations involving only the superficial mucosa. They did not penetrate beyond the submucosa. PC caused gastroenteritis characterized by inflammatory infiltrations localized in the submucosa. These had a granulomatous appearance and contained many large histiocytes. In the chronic studies, numerous foci involving the stomach mucosa and composed of histiocytes, polynuclear eosinophils, and mastocytes were observed. In the small intestine, inflammatory granulomatous infiltrations of the submucosa occurred. These were accompanied by large histiocytes and plasmocytes. No gastroduodenal ulcers were observed. The authors conclude that exposure to PC, even by prolonged ingestion, does not cause gastroduodenal ulcers. (French)","Additional experimental findings To the concept of gastric ulcer frequency among chromium workers Abs: The toxicity of potassium-chromate (7789006) (PC) was studied in guinea-pigs, rats, and rabbits. The animals were administered PC orally, subcutaneously, intraperitoneally, or topically as an ointment containing 1 percent of the compound. The animals were also exposed to an aerosol containing 1 to 2 percent PC. The length of exposure ranged from less than 1 month in the acute and subacute studies to 1 year in the chronic studies. Gross and histopathological examinations were conducted at the end of the experiments. Acute exposure to PC caused superficial ulcerations of the gastric mucosa. Hemorrhagic foci were seen in the stomachs of animals administered PC by the oral, subcutaneous, and intraperitoneal routes. Ulcerative lesions were seen frequently in the small intestine. These were characterized by small superficial ulcerations involving only the superficial mucosa. They did not penetrate beyond the submucosa. PC caused gastroenteritis characterized by inflammatory infiltrations localized in the submucosa. These had a granulomatous appearance and contained many large histiocytes. In the chronic studies, numerous foci involving the stomach mucosa and composed of histiocytes, polynuclear eosinophils, and mastocytes were observed. In the small intestine, inflammatory granulomatous infiltrations of the submucosa occurred. These were accompanied by large histiocytes and plasmocytes. No gastroduodenal ulcers were observed. The authors conclude that exposure to PC, even by prolonged ingestion, does not cause gastroduodenal ulcers. (French)"
1237936,Camarasa 1967,Cobalt Contact Dermatitis,"The sensitizing capacity of cobalt (7440484) in contact dermatitis was investigated in workers. A battery of routine patch tests on 1000 patients with contact dermatitis was conducted with cobalt salts. Three aqueous solutions of potassium-bichromate (7778509), cobalt-chloride (7646799), and cobalt-nitrate (10141056) were injected intradermally in each patient. In epicutaneous tests, 108 of 126 construction workers with cement eczema showed sensitization to the solution of potassium-bichromate. Ninety six also showed sensitization to cobalt-chloride and cobalt-nitrate. Among 56 workers in jobs associated with chromium (7440473) salts, no cases showed positive reactions to cobalt salts. Intradermal reactions were erythematous, slightly edematous, and localized around the papule caused by the injection. Papules remained visible for 2 to 3 days, gradually receded, and disappeared completely in 6 to 8 days. Intradermal injections provoked a vascular and perivascular reaction in which the histological manifestation was a lymphocytic infiltrate with neutrophils and eosinophils in an edematous dermis. Some lesions in the epidermal area adjacent to the more affected dermis were observed. The most characteristic lesions appeared in the lower dermis and rarely in the subcutaneous tissue. The author concludes that patients allergic to cobalt respond intradermally to cobalt salts with the development of a diagnostic papule.","Cobalt Contact Dermatitis Abs: The sensitizing capacity of cobalt (7440484) in contact dermatitis was investigated in workers. A battery of routine patch tests on 1000 patients with contact dermatitis was conducted with cobalt salts. Three aqueous solutions of potassium-bichromate (7778509), cobalt-chloride (7646799), and cobalt-nitrate (10141056) were injected intradermally in each patient. In epicutaneous tests, 108 of 126 construction workers with cement eczema showed sensitization to the solution of potassium-bichromate. Ninety six also showed sensitization to cobalt-chloride and cobalt-nitrate. Among 56 workers in jobs associated with chromium (7440473) salts, no cases showed positive reactions to cobalt salts. Intradermal reactions were erythematous, slightly edematous, and localized around the papule caused by the injection. Papules remained visible for 2 to 3 days, gradually receded, and disappeared completely in 6 to 8 days. Intradermal injections provoked a vascular and perivascular reaction in which the histological manifestation was a lymphocytic infiltrate with neutrophils and eosinophils in an edematous dermis. Some lesions in the epidermal area adjacent to the more affected dermis were observed. The most characteristic lesions appeared in the lower dermis and rarely in the subcutaneous tissue. The author concludes that patients allergic to cobalt respond intradermally to cobalt salts with the development of a diagnostic papule."
1237935,Fleischer et al. 1944,The Health Hazards Of Welding Fumes,"Health hazards associated with exposure to welding fumes are discussed. Welding processes are described, and different types of welding electrodes are reviewed, including shielded arcs, coated electrodes, welding electrodes, and stainless steel. Tabulated data is provided on the metal content of wire used in steel and stainless steel welding electrodes, and on the components of the coating used on these electrodes. A typical fume profile is given for stainless steel welding. Gases evolved during welding include nitrogen-dioxide (10102440), carbon-dioxide (124389), and fluoride compounds. Toxic hazards are discussed for zinc-oxide (1314132), iron-oxide (1332372), chromium-oxide (11118573), and lead-oxide (1335257). The findings of surveys of respiratory disease among welders are examined, such as changes in lung function, chest X-rays, lung histology, and increased incidence of pneumonia. The use of ventilation to reduce and control exposures to welding fumes is described, and recommended maximum concentrations are given for zinc-oxide and iron-oxide. The authors conclude that provision of good ventilation can eliminate most of the hazards of welding fume exposure.","The Health Hazards Of Welding Fumes Abs: Health hazards associated with exposure to welding fumes are discussed. Welding processes are described, and different types of welding electrodes are reviewed, including shielded arcs, coated electrodes, welding electrodes, and stainless steel. Tabulated data is provided on the metal content of wire used in steel and stainless steel welding electrodes, and on the components of the coating used on these electrodes. A typical fume profile is given for stainless steel welding. Gases evolved during welding include nitrogen-dioxide (10102440), carbon-dioxide (124389), and fluoride compounds. Toxic hazards are discussed for zinc-oxide (1314132), iron-oxide (1332372), chromium-oxide (11118573), and lead-oxide (1335257). The findings of surveys of respiratory disease among welders are examined, such as changes in lung function, chest X-rays, lung histology, and increased incidence of pneumonia. The use of ventilation to reduce and control exposures to welding fumes is described, and recommended maximum concentrations are given for zinc-oxide and iron-oxide. The authors conclude that provision of good ventilation can eliminate most of the hazards of welding fume exposure."
1237934,Adams and  Nicholls 1929,"The Analysis Of Mixtures Containing Acetone, Ethyl Alcohol, And Isopropyl Alcohol","Analytical methods for determining acetone (67641), ethyl-alcohol (64175), and isopropyl-alcohol (67630) in mixtures were described. Immersion refractometry was used to determine the compounds if the total concentration was less than 10 percent by volume. Acetone was also determined by a colorimetric procedure. After mixing the sample, 0.5 milliliter (ml) of 30 percent sodium-hydroxide (NaOH) was added, and the solution was allowed to stand 15 minutes. The color was compared to that of a set of standard acetone solutions. This method was used with samples containing up to 0.02 grams (g) acetone. Isopropyl-alcohol was determined by a variation of the procedure. Isopropyl-alcohol was oxidized to acetone by adding 5ml of saturated bromine water to 10ml of the sample. The solution was allowed to stand 3 to 6 hours in a cool, dark place. One milliliter of 1 percent NaOH was added, followed by 2ml of 30 percent NaOH. After standing 15 minutes, the color was compared to that of a set of standards. The amount of acetone found represented the amount originally present plus that formed by the oxidation of isopropyl-alcohol. The amount of isopropyl-alcohol was found by subtracting the amount of acetone present originally. This procedure determined 0.025ml isopropyl-alcohol in a 10ml sample. Ethyl-alcohol was determined by a procedure based on potassium-dichromate oxidation. A solution containing 10g potassium-dichromate and 25ml concentrated sulfuric-acid per 100ml water was added to a sample of equal volume. The resulting acetic-acid was steam distilled and titrated with a 1 Normal solution of NaOH. In the titration, 1ml of NaOH was equal to 0.058ml ethyl-alcohol.","The Analysis Of Mixtures Containing Acetone, Ethyl Alcohol, And Isopropyl Alcohol Abs: Analytical methods for determining acetone (67641), ethyl-alcohol (64175), and isopropyl-alcohol (67630) in mixtures were described. Immersion refractometry was used to determine the compounds if the total concentration was less than 10 percent by volume. Acetone was also determined by a colorimetric procedure. After mixing the sample, 0.5 milliliter (ml) of 30 percent sodium-hydroxide (NaOH) was added, and the solution was allowed to stand 15 minutes. The color was compared to that of a set of standard acetone solutions. This method was used with samples containing up to 0.02 grams (g) acetone. Isopropyl-alcohol was determined by a variation of the procedure. Isopropyl-alcohol was oxidized to acetone by adding 5ml of saturated bromine water to 10ml of the sample. The solution was allowed to stand 3 to 6 hours in a cool, dark place. One milliliter of 1 percent NaOH was added, followed by 2ml of 30 percent NaOH. After standing 15 minutes, the color was compared to that of a set of standards. The amount of acetone found represented the amount originally present plus that formed by the oxidation of isopropyl-alcohol. The amount of isopropyl-alcohol was found by subtracting the amount of acetone present originally. This procedure determined 0.025ml isopropyl-alcohol in a 10ml sample. Ethyl-alcohol was determined by a procedure based on potassium-dichromate oxidation. A solution containing 10g potassium-dichromate and 25ml concentrated sulfuric-acid per 100ml water was added to a sample of equal volume. The resulting acetic-acid was steam distilled and titrated with a 1 Normal solution of NaOH. In the titration, 1ml of NaOH was equal to 0.058ml ethyl-alcohol."
1237931,Winteringham 1942,Determination Of Fumigants. XIII. Determination Of Chlorohydrocarbons By Thermal Decomposition,"A procedure for the determination of chlorohydrocarbons using thermal decomposition was developed. The airstream containing the sample was drawn into the thermal decomposition apparatus by means of a rotary vacuum pump. The inlet contained cotton wool as a dust filter. The sample passed through three towers packed respectively with caustic soda, calcium-chloride, and activated charcoal. The air was then directed into an aeration flask, either directly or via a bubbler containing distilled water. Dry or moist air then entered the thermal decomposition tube. This was a transparent silica tube, kept at about 900 degrees-C by an electric furnace. The air and decomposition products were bubbled through two sintered glass plate bubblers charged with 2 normal (N) sodium-hydroxide. The chloride (16887006) present was determined by titrating with 0.1N silver-nitrate, using a potassium-chromate indicator. Before titration, any hypochlorites present were reduced with sodium-sulfite. The precision of the method was tested using milligram quantities of chloroform (67663), carbon-tetrachloride (56235), pentachloroethane (76017), trichloroethylene (79016), tetrachloroethylene (127184), and methylallyl-chloride (563473). Recoveries ranged from 95 to 105 percent. The method was applicable to samples drawn in evacuated flasks, using castor-oil as a solvent. The sampling head could be replaced by the aeration head necessary for the thermal decomposition apparatus without loss of sample. The author concludes that this method can be useful for the determination of chlorohydrocarbons in samples of fumigated material.","Determination Of Fumigants. XIII. Determination Of Chlorohydrocarbons By Thermal Decomposition Abs: A procedure for the determination of chlorohydrocarbons using thermal decomposition was developed. The airstream containing the sample was drawn into the thermal decomposition apparatus by means of a rotary vacuum pump. The inlet contained cotton wool as a dust filter. The sample passed through three towers packed respectively with caustic soda, calcium-chloride, and activated charcoal. The air was then directed into an aeration flask, either directly or via a bubbler containing distilled water. Dry or moist air then entered the thermal decomposition tube. This was a transparent silica tube, kept at about 900 degrees-C by an electric furnace. The air and decomposition products were bubbled through two sintered glass plate bubblers charged with 2 normal (N) sodium-hydroxide. The chloride (16887006) present was determined by titrating with 0.1N silver-nitrate, using a potassium-chromate indicator. Before titration, any hypochlorites present were reduced with sodium-sulfite. The precision of the method was tested using milligram quantities of chloroform (67663), carbon-tetrachloride (56235), pentachloroethane (76017), trichloroethylene (79016), tetrachloroethylene (127184), and methylallyl-chloride (563473). Recoveries ranged from 95 to 105 percent. The method was applicable to samples drawn in evacuated flasks, using castor-oil as a solvent. The sampling head could be replaced by the aeration head necessary for the thermal decomposition apparatus without loss of sample. The author concludes that this method can be useful for the determination of chlorohydrocarbons in samples of fumigated material."
1237930,Adamska 1971,On Allergic Reactions To Detergents,"The properties of allergizing, synthetic detergents and sensitization to standard allergens were investigated. A group of 422 subjects ranging in age from 9 to 70 years old underwent thorough examination for incidence of allergic diseases with special attention to allergic reactions due to use of detergents. Research subjects were divided into two groups. Group 1 consisted of 38 subjects with active skin changes of an eczematous nature located on the hands. Group 2 consisted of 384 subjects that indicated no cases of allergic dermatitis. Lamellar tests were performed with water solutions containing formalin (50000), potassium-dichromate (7778509), cobaltous-chloride (7646799), and nickel-sulfate (7786814). Lamellar tests were also performed with several detergents and washing powders. Lamellar tests were placed on the skin of the back for an exposure period of 24 hours. Positive reactions to detergents occurred among subjects with active eczematous changes; washing powders did not cause any positive reactions. Nickel and cobalt produced the greatest allergizing action among the subjects with active eczematous changes. The author concludes that subjects with eczema are more sensitive to the allergic effects of detergents, nickel-sulfate, and cobaltous-chloride. (Polish)","On Allergic Reactions To Detergents Abs: The properties of allergizing, synthetic detergents and sensitization to standard allergens were investigated. A group of 422 subjects ranging in age from 9 to 70 years old underwent thorough examination for incidence of allergic diseases with special attention to allergic reactions due to use of detergents. Research subjects were divided into two groups. Group 1 consisted of 38 subjects with active skin changes of an eczematous nature located on the hands. Group 2 consisted of 384 subjects that indicated no cases of allergic dermatitis. Lamellar tests were performed with water solutions containing formalin (50000), potassium-dichromate (7778509), cobaltous-chloride (7646799), and nickel-sulfate (7786814). Lamellar tests were also performed with several detergents and washing powders. Lamellar tests were placed on the skin of the back for an exposure period of 24 hours. Positive reactions to detergents occurred among subjects with active eczematous changes; washing powders did not cause any positive reactions. Nickel and cobalt produced the greatest allergizing action among the subjects with active eczematous changes. The author concludes that subjects with eczema are more sensitive to the allergic effects of detergents, nickel-sulfate, and cobaltous-chloride. (Polish)"
1237925,Newman and  Abramson 1942,Determination Of Ethyl Alcohol With The Photoelectric Colorimeter,"A method for the determination of ethyl-alcohol (64175) in body fluids was discussed. To anhydrous sodium-sulfate, 1 milliliter (ml) of sample was added. The alcohol was distilled through a vacuum pump at 50 to 55 degrees-C into 3ml of potassium-dichromate at a 300 milligram (mg) to 100ml concentration dissolved in concentrated sulfuric-acid for 20 minutes. The dichromate was diluted to 25ml with water and examined under a colorimeter at a wave length of 480 millimicrons in 30 percent transmittance. The results were determined by reading against a calibration curve of known alcohol concentration. The curve points were run in triplicate for best results. The increase in distillation temperature and the warming of the delivery tube eliminated some aberrant results found in other methods, but it did not improve the probable error of 3.5 percent for concentrations in excess of 25mg per 100ml. The authors conclude that this methodology is ideal for medical or legal work and its accuracy is adequate for research purposes.","Determination Of Ethyl Alcohol With The Photoelectric Colorimeter Abs: A method for the determination of ethyl-alcohol (64175) in body fluids was discussed. To anhydrous sodium-sulfate, 1 milliliter (ml) of sample was added. The alcohol was distilled through a vacuum pump at 50 to 55 degrees-C into 3ml of potassium-dichromate at a 300 milligram (mg) to 100ml concentration dissolved in concentrated sulfuric-acid for 20 minutes. The dichromate was diluted to 25ml with water and examined under a colorimeter at a wave length of 480 millimicrons in 30 percent transmittance. The results were determined by reading against a calibration curve of known alcohol concentration. The curve points were run in triplicate for best results. The increase in distillation temperature and the warming of the delivery tube eliminated some aberrant results found in other methods, but it did not improve the probable error of 3.5 percent for concentrations in excess of 25mg per 100ml. The authors conclude that this methodology is ideal for medical or legal work and its accuracy is adequate for research purposes."
1237924,Bowszyc 1965,"Sensitization To Chromium, Cobalt And Nickel Compounds Of Patients With Occupational Eczema","The occurrence of sensitization to chromium-chloride (10025737), nickel-sulfate (7786814), and potassium-dichromate (7778509) was tested among workers in several industrial facilities in Gdansk, Poland. Patch tests using the compounds were administered to 250 patients with eczema and to 61 healthy employees. Seven health workers and 95 affected with eczema showed positive reactions to chromium (7440473), nickel (7440020), or cobalt (7440484). Eighty percent of the workers were employed in the building, metal, leather and fur, and oil and fat industries. Sensitization to cobalt was less frequent than to chromium, but often occurred together in particular industries. Combined sensitization to chromium and cobalt was most frequent among masons, metallurgists, tanners, and furriers. Cross sensitization to chromium, nickel, and cobalt compounds was much less frequent and usually was observed in patients with prolonged and severe cases of eczema. Several fat industry workers occupationally exposed to nickel were sensitized to nickel. This group of workers also had the highest percentage of sensitization to cobalt alone or in combination with nickel. The author concludes that workers may become sensitized to nickel, chromium, and cobalt compounds due to occupational exposure. Primary sensitization to cobalt does not commonly occur, but cross sensitization to chromium and cobalt as well as to nickel and cobalt does occur. (Polish)","Sensitization To Chromium, Cobalt And Nickel Compounds Of Patients With Occupational Eczema Abs: The occurrence of sensitization to chromium-chloride (10025737), nickel-sulfate (7786814), and potassium-dichromate (7778509) was tested among workers in several industrial facilities in Gdansk, Poland. Patch tests using the compounds were administered to 250 patients with eczema and to 61 healthy employees. Seven health workers and 95 affected with eczema showed positive reactions to chromium (7440473), nickel (7440020), or cobalt (7440484). Eighty percent of the workers were employed in the building, metal, leather and fur, and oil and fat industries. Sensitization to cobalt was less frequent than to chromium, but often occurred together in particular industries. Combined sensitization to chromium and cobalt was most frequent among masons, metallurgists, tanners, and furriers. Cross sensitization to chromium, nickel, and cobalt compounds was much less frequent and usually was observed in patients with prolonged and severe cases of eczema. Several fat industry workers occupationally exposed to nickel were sensitized to nickel. This group of workers also had the highest percentage of sensitization to cobalt alone or in combination with nickel. The author concludes that workers may become sensitized to nickel, chromium, and cobalt compounds due to occupational exposure. Primary sensitization to cobalt does not commonly occur, but cross sensitization to chromium and cobalt as well as to nickel and cobalt does occur. (Polish)"
1237923,Weichselbaum and  Somogyi 1941,A Method For The Determination Of Small Amounts Of Ketone Bodies,"A method for determining total ketone bodies in blood, based on recovery of beta-hydroxybutyric-acid (300856) was developed and tested. To remove proteins and sugars from organic substances in the blood, 5 cubic centimeters (cm3) of blood was added to 10cm3 of water with barium-hydroxide and 10cm3 zinc-sulfate. After centrifuging, 21cm3 of the filtrate was mixed with 4.5cm3 of lead-acetate and 4.5cm3 of a phosphate reagent. After shaking, from 0.1 to 0.2 grams (gm) sodium-sulfate was added and shaken. After centrifuging and filtering, 25cm3 of sugar free filtrate, corresponding to 2.5cm3 of blood, was ready for acetone analysis. Oxidation of beta-hydroxybutyric-acid along with formation of acetone (67641) were used to determine total ketone bodies. Reagents necessary for the oxidation were a 20 normal solution of sulfuric-acid, a 2.5 percent potassium-dichromate solution, Denigre's reagent, and a 0.3 percent barium-chloride solution. Distillation was carried out by immersing the distilling flask containing the blood filtrate into boiling water. At various points, the different reagents were added. After 100 minutes, the mixture was centrifuged. The acetone content was determined by the iodometric method after decomposition of the mercury compound. Reagents used in this process were a 10 percent potassium-iodide solution, a 2.5 normal sodium-hydroxide solution, iodine, a 0.005 normal sodium-thiosulfite solution, and a 0.5 percent starch indicator. When total ketone bodies were figured, 1cm3 of the iodine consumed equaled 0.116 milligrams (mg) of total ketone bodies, expressed in terms of beta-hydroxybutyric-acid. When known amounts of acetoacetic-acid (541504) and beta-hydroxybutyric-acid were added to blood samples in which the original ketone body content had been determined, there were relatively slight discrepancies between the quantities added and recovered. For example, 2.0mg beta-hydroxybutyric-acid added to 7.34mg total amount yielded 2.08mg, with an error rate of 4.0 percent. A determination of total ketone bodies in the blood of 16 persons yielded 0.33 to 0.94mg per 100cm3 blood expressed as beta-hydroxybutyric-acid. The average value of blood ketone was 0.5mg percent.","A Method For The Determination Of Small Amounts Of Ketone Bodies Abs: A method for determining total ketone bodies in blood, based on recovery of beta-hydroxybutyric-acid (300856) was developed and tested. To remove proteins and sugars from organic substances in the blood, 5 cubic centimeters (cm3) of blood was added to 10cm3 of water with barium-hydroxide and 10cm3 zinc-sulfate. After centrifuging, 21cm3 of the filtrate was mixed with 4.5cm3 of lead-acetate and 4.5cm3 of a phosphate reagent. After shaking, from 0.1 to 0.2 grams (gm) sodium-sulfate was added and shaken. After centrifuging and filtering, 25cm3 of sugar free filtrate, corresponding to 2.5cm3 of blood, was ready for acetone analysis. Oxidation of beta-hydroxybutyric-acid along with formation of acetone (67641) were used to determine total ketone bodies. Reagents necessary for the oxidation were a 20 normal solution of sulfuric-acid, a 2.5 percent potassium-dichromate solution, Denigre's reagent, and a 0.3 percent barium-chloride solution. Distillation was carried out by immersing the distilling flask containing the blood filtrate into boiling water. At various points, the different reagents were added. After 100 minutes, the mixture was centrifuged. The acetone content was determined by the iodometric method after decomposition of the mercury compound. Reagents used in this process were a 10 percent potassium-iodide solution, a 2.5 normal sodium-hydroxide solution, iodine, a 0.005 normal sodium-thiosulfite solution, and a 0.5 percent starch indicator. When total ketone bodies were figured, 1cm3 of the iodine consumed equaled 0.116 milligrams (mg) of total ketone bodies, expressed in terms of beta-hydroxybutyric-acid. When known amounts of acetoacetic-acid (541504) and beta-hydroxybutyric-acid were added to blood samples in which the original ketone body content had been determined, there were relatively slight discrepancies between the quantities added and recovered. For example, 2.0mg beta-hydroxybutyric-acid added to 7.34mg total amount yielded 2.08mg, with an error rate of 4.0 percent. A determination of total ketone bodies in the blood of 16 persons yielded 0.33 to 0.94mg per 100cm3 blood expressed as beta-hydroxybutyric-acid. The average value of blood ketone was 0.5mg percent."
1237922,Nilzen and  Wikstrom 1955,The Influence of Lauryl Sulphate on the Sensitization of Guineapigs to Chrome and Nickel,"The influence of lauryl-sulfate (151417) (LS) on the sensitization of guinea-pigs to chrome (7440473) and nickel (7440020), was studied. Twenty five white guinea-pigs were shaved on one side of the body and divided into five groups. Animals were painted daily for 8 days with 1 percent aqueous solution of LS (Group 1), 0.5 percent aqueous solution of potassium-dichromate (7778509) (Group 2), 4 percent aqueous solution of nickel-sulfate (7786814) (Group 3), a mixture of 1 percent LS and potassium-dichromate in aqueous solution (Group 4), or a mixture of 1 percent LS and 4 percent nickel-sulfate in aqueous solutions (Group 5). Skin alterations and skin biopsies were examined after these applications. Animals showing skin reactions were tested 12 days after application for sensitivity to compounds causing the reactions. No skin reactions were seen in animals from the first three groups. In the fourth group, painted with LS and potassium-dichromate, lesions consisting of scaling and erythema, and appreciable infiltration was seen. Testing with both potassium-dichromate and the mixture of LS and potassium-dichromate evoked distinct erythema and infiltration; tests with LS alone were negative. In four animals painted with LS and nickel-sulfate mild erythema was seen. In the fifth, there was grossly marked scaling and infiltration; this animal gave a distinctly positive reaction to testing with nickel-sulfate and nickel-sulfate plus LS. The remaining four did not respond. Skin biopsies were normal for groups 2 and 3. Animals treated with LS alone had hyperkeratosis, thickened epidermis with moderate edema and some invasion by leukocytes. In groups 4 and 5 the epidermis showed marked thickening and edema. Intracellular edema was more pronounced within well defined areas showing large amounts of leucocytes. The authors conclude that LS is capable of activating the eczematogenic properties of simple chemical compounds in guinea-pigs. The clinical and histological features of eczema in these animals accord well with those of contact dermatitis in humans.","The Influence of Lauryl Sulphate on the Sensitization of Guineapigs to Chrome and Nickel Abs: The influence of lauryl-sulfate (151417) (LS) on the sensitization of guinea-pigs to chrome (7440473) and nickel (7440020), was studied. Twenty five white guinea-pigs were shaved on one side of the body and divided into five groups. Animals were painted daily for 8 days with 1 percent aqueous solution of LS (Group 1), 0.5 percent aqueous solution of potassium-dichromate (7778509) (Group 2), 4 percent aqueous solution of nickel-sulfate (7786814) (Group 3), a mixture of 1 percent LS and potassium-dichromate in aqueous solution (Group 4), or a mixture of 1 percent LS and 4 percent nickel-sulfate in aqueous solutions (Group 5). Skin alterations and skin biopsies were examined after these applications. Animals showing skin reactions were tested 12 days after application for sensitivity to compounds causing the reactions. No skin reactions were seen in animals from the first three groups. In the fourth group, painted with LS and potassium-dichromate, lesions consisting of scaling and erythema, and appreciable infiltration was seen. Testing with both potassium-dichromate and the mixture of LS and potassium-dichromate evoked distinct erythema and infiltration; tests with LS alone were negative. In four animals painted with LS and nickel-sulfate mild erythema was seen. In the fifth, there was grossly marked scaling and infiltration; this animal gave a distinctly positive reaction to testing with nickel-sulfate and nickel-sulfate plus LS. The remaining four did not respond. Skin biopsies were normal for groups 2 and 3. Animals treated with LS alone had hyperkeratosis, thickened epidermis with moderate edema and some invasion by leukocytes. In groups 4 and 5 the epidermis showed marked thickening and edema. Intracellular edema was more pronounced within well defined areas showing large amounts of leucocytes. The authors conclude that LS is capable of activating the eczematogenic properties of simple chemical compounds in guinea-pigs. The clinical and histological features of eczema in these animals accord well with those of contact dermatitis in humans."
1237921,Zawadski 1961,A Rapid Determination of Styrene in Air,"Three colorimetric methods for determination of styrene (100425) in air were assessed. In the first method, styrene vapor was absorbed in an ice cooled scrubber containing carbon-tetrachloride. The resulting solution was treated with a nitrating solution, containing nitric-acid and sulfuric-acid, and the colored nitro derivative was extracted with water. Styrene content of the water solution was determined using standard colorimetric techniques. The second analytical method was essentially the same except that styrene vapor was absorbed in a column filled with silica gel and then resorbed by shaking with carbon-tetrachloride. In the third method, styrene was absorbed directly in a nitrating mixture made up of ammonium-nitrate and concentrated sulfuric-acid. Determination of styrene concentration using this solution was accomplished using standard colorimetric techniques. For the newly developed method, based on the third method described, styrene vapor was collected in an absorber containing ammonium-nitrate and sulfuric-acid. The solution was transferred to colorimetric test tubes and made up to volume with distilled water and styrene concentrations were determined colorimetrically. Three sets of standards consisting of styrene in carbon-tetrachloride, cobalt-sulfate in water, or potassium-dichromate in water were prepared. The third method tested was judged to be the simplest and most efficient. Complete absorption of styrene was obtained and because shorter sampling times and fewer steps were required, the total time for determination was the shortest of the three methods. The nitrating mixture containing ammonium-nitrate was superior to the one containing nitric-acid. Colored solutions were not cloudy as they were with the nitric-acid solutions, large quantities of acid fumes were not given off, and nitration occurred more quickly. The newly developed technique gave excellent results. Determinations were accurate and quickly performed. Determination of concentrations as low as 0.1 milligram styrene per liter of air were easily accomplished. The artificial standards compared well with standards prepared using styrene. They were preferable because the standards containing styrene were not persistent and faded in a few hours. (Polish)","A Rapid Determination of Styrene in Air Abs: Three colorimetric methods for determination of styrene (100425) in air were assessed. In the first method, styrene vapor was absorbed in an ice cooled scrubber containing carbon-tetrachloride. The resulting solution was treated with a nitrating solution, containing nitric-acid and sulfuric-acid, and the colored nitro derivative was extracted with water. Styrene content of the water solution was determined using standard colorimetric techniques. The second analytical method was essentially the same except that styrene vapor was absorbed in a column filled with silica gel and then resorbed by shaking with carbon-tetrachloride. In the third method, styrene was absorbed directly in a nitrating mixture made up of ammonium-nitrate and concentrated sulfuric-acid. Determination of styrene concentration using this solution was accomplished using standard colorimetric techniques. For the newly developed method, based on the third method described, styrene vapor was collected in an absorber containing ammonium-nitrate and sulfuric-acid. The solution was transferred to colorimetric test tubes and made up to volume with distilled water and styrene concentrations were determined colorimetrically. Three sets of standards consisting of styrene in carbon-tetrachloride, cobalt-sulfate in water, or potassium-dichromate in water were prepared. The third method tested was judged to be the simplest and most efficient. Complete absorption of styrene was obtained and because shorter sampling times and fewer steps were required, the total time for determination was the shortest of the three methods. The nitrating mixture containing ammonium-nitrate was superior to the one containing nitric-acid. Colored solutions were not cloudy as they were with the nitric-acid solutions, large quantities of acid fumes were not given off, and nitration occurred more quickly. The newly developed technique gave excellent results. Determinations were accurate and quickly performed. Determination of concentrations as low as 0.1 milligram styrene per liter of air were easily accomplished. The artificial standards compared well with standards prepared using styrene. They were preferable because the standards containing styrene were not persistent and faded in a few hours. (Polish)"
1237920,Marcussen 1962,Variations in the Incidence of Contact Hypersensitivities,"Variations in the incidence of contact hypersensitivities to 2 standard patch test series of 21 substances were examined. Subjects were 36,000 patients with dermatitis, tested in a dermatological department in Copenhagen, Denmark, between 1938 and 1955. Substances tested for included: turpentine (8006642), colophony (8050097), balsam-of-Peru (8007009), salicylic-acid (69727), formalin (50000), mercuric-chloride (7487947), potassium-dichromate (7778509), silver-nitrate (7761888), nickel-sulfate (7786814), resorcin (108463), sodium-perborate (11138479) powder, brown soap, pure coal-tar (8007452), wood tars, quinine-hydrochloride (130892), iodine (7553562), pyrogallol (87661), paraphenylenediamine (92671), para-aminophenol (123308), and adhesive tape. Of subjects tested, 29.6 percent showed positive reactions to one or more of these substances. An examination of hypersensitivities over time to substances of therapeutic use indicated that hypersensitivity to iodine almost completely disappeared, and decreased markedly to quinine and resorcin. Hypersensitivities to salicyclic-acid and coal-tar showed significant increases, and hypersensitivity to balsam-of-Peru also increased. Four substances, imported on a large scale for industrial use, showed a marked decrease in hypersensitivity toward the end of World War II, followed by a renewed increase. These were nickel formaldehyde, colophony, and potassium-dichromate. The author suggests that increases and decreases in hypersensitivities over the time period studied correlate to the increasing or decreasing use of the substance.","Variations in the Incidence of Contact Hypersensitivities Abs: Variations in the incidence of contact hypersensitivities to 2 standard patch test series of 21 substances were examined. Subjects were 36,000 patients with dermatitis, tested in a dermatological department in Copenhagen, Denmark, between 1938 and 1955. Substances tested for included: turpentine (8006642), colophony (8050097), balsam-of-Peru (8007009), salicylic-acid (69727), formalin (50000), mercuric-chloride (7487947), potassium-dichromate (7778509), silver-nitrate (7761888), nickel-sulfate (7786814), resorcin (108463), sodium-perborate (11138479) powder, brown soap, pure coal-tar (8007452), wood tars, quinine-hydrochloride (130892), iodine (7553562), pyrogallol (87661), paraphenylenediamine (92671), para-aminophenol (123308), and adhesive tape. Of subjects tested, 29.6 percent showed positive reactions to one or more of these substances. An examination of hypersensitivities over time to substances of therapeutic use indicated that hypersensitivity to iodine almost completely disappeared, and decreased markedly to quinine and resorcin. Hypersensitivities to salicyclic-acid and coal-tar showed significant increases, and hypersensitivity to balsam-of-Peru also increased. Four substances, imported on a large scale for industrial use, showed a marked decrease in hypersensitivity toward the end of World War II, followed by a renewed increase. These were nickel formaldehyde, colophony, and potassium-dichromate. The author suggests that increases and decreases in hypersensitivities over the time period studied correlate to the increasing or decreasing use of the substance."
1237918,Grosfeld et al. 1966,In Vitro Investigations of Chromiumand Nickel-Hypersensitivity with Culture of Skin and Peripheral Lymphocytes,"The growth of skin and lymphocyte cells was studied in patients with chromium (7440473) and nickel (7440020) sensitivity. Skin samples from chromium sensitized and normal subjects were cultured with 0, 0.000001, and 0.0000001 molar concentrations of potassium-bichromate (7778509), all and outgrowth of the cells was determined for 4 days. Peripheral lymphocytes from nickel and chromium sensitized subjects, and from normal subjects, were incubated with 0.000001 to 0.00000001 milliequivalent per milliliter of nickel or chromium antigen. Phytohemagglutinin (PHA) was added to the cultures. Cell mitoses were counted after 72 to 96 hours. No difference in cell outgrowth was found between cell cultures from chromium sensitized and normal subjects, in the presence or absence of potassium-bichromate. Results in peripheral lymphocytes were conclusive: both positive and negative reactions were seen. The authors conclude that the skin culture system is not suitable for demonstrating delayed hypersensitivity in-vitro. The inconsistencies in the lymphocyte tests may be due to a nonspecific effect of the presence of PHA.","In Vitro Investigations of Chromiumand Nickel-Hypersensitivity with Culture of Skin and Peripheral Lymphocytes Abs: The growth of skin and lymphocyte cells was studied in patients with chromium (7440473) and nickel (7440020) sensitivity. Skin samples from chromium sensitized and normal subjects were cultured with 0, 0.000001, and 0.0000001 molar concentrations of potassium-bichromate (7778509), all and outgrowth of the cells was determined for 4 days. Peripheral lymphocytes from nickel and chromium sensitized subjects, and from normal subjects, were incubated with 0.000001 to 0.00000001 milliequivalent per milliliter of nickel or chromium antigen. Phytohemagglutinin (PHA) was added to the cultures. Cell mitoses were counted after 72 to 96 hours. No difference in cell outgrowth was found between cell cultures from chromium sensitized and normal subjects, in the presence or absence of potassium-bichromate. Results in peripheral lymphocytes were conclusive: both positive and negative reactions were seen. The authors conclude that the skin culture system is not suitable for demonstrating delayed hypersensitivity in-vitro. The inconsistencies in the lymphocyte tests may be due to a nonspecific effect of the presence of PHA."
1237917,Greenburg et al. 1942,The Effects of Exposure to Toluene in Industry,"Manifestations of toluene (108883) were evaluated in an airplane factory (SIC-3721). Personal area air samples were collected and physical examinations were conducted of 106 aircraft painters, 30 exposed to benzene, and 15 to unidentified volatile solvents within 4 to 24 months of the study. The remaining 61 were considered uncomplicated exposures. Although toluene accounted for most of the exposure, other volatile and nonvolatile compounds were detected. Medical histories were taken, and blood and urine analyses were performed. Toluene exposures ranged from 100 to 1100 parts per million (ppm). Medical histories indicated all workers were symptomless. Perforated nasal septa and enlargement of the liver were found in 5 and 32 workers, respectively. Perforated nasal septa was associated with zinc-chromate (13530659) exposure. Of the 32 workers with liver enlargement, 21.4 percent were in the uncomplicated group. Erythrocyte counts were depressed in 17 percent, compared to 5.2 percent of comparisons. Hemoglobin was elevated in 37.7 percent of the cases, compared to 2.4 percent of comparisons. Elevated absolute lymphocyte counts were found in 19.5 percent, versus 7.7 percent of comparisons. Mean corpuscular volume was elevated in 23.6 percent (21.3 percent of the uncomplicated exposures) compared to 7.2 percent comparisons. Mean corpuscular hemoglobin and mean corpuscular hemoglobin concentrations were elevated in 17.9 and 39.7 percent of the cases, compared to 0 and 2.5 percent of comparisons. Urinary findings were within control limits. The authors conclude that hepatomegaly and macrocytosis are indicative of early chronic toluene intoxication.","The Effects of Exposure to Toluene in Industry Abs: Manifestations of toluene (108883) were evaluated in an airplane factory (SIC-3721). Personal area air samples were collected and physical examinations were conducted of 106 aircraft painters, 30 exposed to benzene, and 15 to unidentified volatile solvents within 4 to 24 months of the study. The remaining 61 were considered uncomplicated exposures. Although toluene accounted for most of the exposure, other volatile and nonvolatile compounds were detected. Medical histories were taken, and blood and urine analyses were performed. Toluene exposures ranged from 100 to 1100 parts per million (ppm). Medical histories indicated all workers were symptomless. Perforated nasal septa and enlargement of the liver were found in 5 and 32 workers, respectively. Perforated nasal septa was associated with zinc-chromate (13530659) exposure. Of the 32 workers with liver enlargement, 21.4 percent were in the uncomplicated group. Erythrocyte counts were depressed in 17 percent, compared to 5.2 percent of comparisons. Hemoglobin was elevated in 37.7 percent of the cases, compared to 2.4 percent of comparisons. Elevated absolute lymphocyte counts were found in 19.5 percent, versus 7.7 percent of comparisons. Mean corpuscular volume was elevated in 23.6 percent (21.3 percent of the uncomplicated exposures) compared to 7.2 percent comparisons. Mean corpuscular hemoglobin and mean corpuscular hemoglobin concentrations were elevated in 17.9 and 39.7 percent of the cases, compared to 0 and 2.5 percent of comparisons. Urinary findings were within control limits. The authors conclude that hepatomegaly and macrocytosis are indicative of early chronic toluene intoxication."
1237916,Gellin et al. 1970,Depigmentation from 4-Tertiary Butyl Catechol An Experimental Study,"The depigmentation of skin by 4-tertiary-butyl-catechol (98293) (TBC) was investigated in human subjects. Four workers exhibiting leucoderma of hands and forearms were patch tested with TBC, potassium-dichromate (7778509), nickel-chloride (7718549), assembly oil, and the inner lining of rubber gloves sometimes worn by the workers. Application and occlusion was performed on six volunteers daily for 7 to 14 days of assembly oils with and without TBC, pure TBC, TBC in propylene-glycol (57556), and propylene-glycol alone. Combinations of substances were also applied to white-rabbits and black and albino-guinea-pigs. The workers did not exhibit any reaction to the patch tests except for the TBC, in which 3 of the 4 developed positive reactions with depigmentation in 1 subject. All volunteers had irritant reactions to assembly oil with stronger reactions in 2 subjects if TBE was present. There was no reaction with propylene-glycol unless TBC was present. No depigmentation occurred. In the rabbit, 100 percent TBC produced a transient reaction, and necrosis was induced when it was placed on the ear. In guinea-pigs, depigmentation occurred in black animals at high concentrations of TBC and was confined to the test site. Hyperpigmentation occurred with TBC in assembly oil after inflammation from irritation of the area. Albino-guinea-pigs were not sensitized. The authors conclude that TBC has the ability to depigment black guinea-pig skin, and the mechanism is not known.","Depigmentation from 4-Tertiary Butyl Catechol An Experimental Study Abs: The depigmentation of skin by 4-tertiary-butyl-catechol (98293) (TBC) was investigated in human subjects. Four workers exhibiting leucoderma of hands and forearms were patch tested with TBC, potassium-dichromate (7778509), nickel-chloride (7718549), assembly oil, and the inner lining of rubber gloves sometimes worn by the workers. Application and occlusion was performed on six volunteers daily for 7 to 14 days of assembly oils with and without TBC, pure TBC, TBC in propylene-glycol (57556), and propylene-glycol alone. Combinations of substances were also applied to white-rabbits and black and albino-guinea-pigs. The workers did not exhibit any reaction to the patch tests except for the TBC, in which 3 of the 4 developed positive reactions with depigmentation in 1 subject. All volunteers had irritant reactions to assembly oil with stronger reactions in 2 subjects if TBE was present. There was no reaction with propylene-glycol unless TBC was present. No depigmentation occurred. In the rabbit, 100 percent TBC produced a transient reaction, and necrosis was induced when it was placed on the ear. In guinea-pigs, depigmentation occurred in black animals at high concentrations of TBC and was confined to the test site. Hyperpigmentation occurred with TBC in assembly oil after inflammation from irritation of the area. Albino-guinea-pigs were not sensitized. The authors conclude that TBC has the ability to depigment black guinea-pig skin, and the mechanism is not known."
1237914,Tizianello et al. 1968,Sites of Destruction of Red Cells in G-6-PD Deficient Caucasians and in Phenylhydrazine Treated Patients,"The hepatic and splenic destruction of glucose-6-phosphate-dehydrogenase (9001405) (G-6-PD) deficient red cells was studied in normal white subjects transfused with G-6-PD deficient cells. Red blood cells labeled with radioactive sodium-chromate (7775113), (Cr-51) were obtained from six Sardinian males with fully expressed G-6-PD deficiency and five female Sardinians with intermediate deficiency. Enzyme deficient cells with maximum specific activity of 25 to 30 microCuries per milligram Cr-51 were transfused into 20 hematologically normal subjects, and one patient with cirrhosis of the liver, splenomegaly, and normal red cell G-6-PD. After transfusion, subjects received 30 milligrams (mg) primaquine (90346) daily for 5 to 8 days; spleen and liver were surface monitored. Survival of Cr-51 labeled red blood cells and cell sequestration in three G-6-PD deficient subjects receiving primaquine (30mg/d) was measured daily in urine radioactivity. Urinary radioactivity was also measured in two patients with polycythemia vera who received phenylhydrazine-chloride (59881), (100mg/d) for 8 to 11 days after Cr-51 labeling of their red cells. In this study, hepatic to splenic uptake of radioactivity showed a consistent ratio of nearly 1 in both normal subjects and G-6-PD deficient subject who had been given primaquine. Splenomegaly enhanced sensitivity to primaquine. In the two cases of polycythemia vera in whom phenylhydrazine caused Heinz body hemolysis, similar splenic uptake of Cr-51 was observed. The authors conclude that both extravascular hemolysis with splenic accumulation of radioactivity, and intravascular hemolysis with splenic accumulation of radioactivity, and intravascular hemolysis with hemoglobinuria, are associated with drug induced hemolytic crises. In the case of patients with disorders such as thalassemia or malaria, the possibility of increased splenic sequestration and destruction of damaged erythrocytes should be considered.","Sites of Destruction of Red Cells in G-6-PD Deficient Caucasians and in Phenylhydrazine Treated Patients Abs: The hepatic and splenic destruction of glucose-6-phosphate-dehydrogenase (9001405) (G-6-PD) deficient red cells was studied in normal white subjects transfused with G-6-PD deficient cells. Red blood cells labeled with radioactive sodium-chromate (7775113), (Cr-51) were obtained from six Sardinian males with fully expressed G-6-PD deficiency and five female Sardinians with intermediate deficiency. Enzyme deficient cells with maximum specific activity of 25 to 30 microCuries per milligram Cr-51 were transfused into 20 hematologically normal subjects, and one patient with cirrhosis of the liver, splenomegaly, and normal red cell G-6-PD. After transfusion, subjects received 30 milligrams (mg) primaquine (90346) daily for 5 to 8 days; spleen and liver were surface monitored. Survival of Cr-51 labeled red blood cells and cell sequestration in three G-6-PD deficient subjects receiving primaquine (30mg/d) was measured daily in urine radioactivity. Urinary radioactivity was also measured in two patients with polycythemia vera who received phenylhydrazine-chloride (59881), (100mg/d) for 8 to 11 days after Cr-51 labeling of their red cells. In this study, hepatic to splenic uptake of radioactivity showed a consistent ratio of nearly 1 in both normal subjects and G-6-PD deficient subject who had been given primaquine. Splenomegaly enhanced sensitivity to primaquine. In the two cases of polycythemia vera in whom phenylhydrazine caused Heinz body hemolysis, similar splenic uptake of Cr-51 was observed. The authors conclude that both extravascular hemolysis with splenic accumulation of radioactivity, and intravascular hemolysis with splenic accumulation of radioactivity, and intravascular hemolysis with hemoglobinuria, are associated with drug induced hemolytic crises. In the case of patients with disorders such as thalassemia or malaria, the possibility of increased splenic sequestration and destruction of damaged erythrocytes should be considered."
1237913,Anonymous 1969,The Inorganic Acids,"The properties and characteristics of the common commercial forms of inorganic acids are discussed. An inorganic acid is a compound of hydrogen and one or more elements (except carbon), which dissociates or breaks down to produce hydrogen ions when dissolved in water or a solvent liquid. The most common inorganic acids used in industry are chromium-trioxide, hydrochloric-acid (7647010), hydrogen-fluoride (7664393), nitric-acid (7697372), perchloric-acid (7601903), orthophosphoric-acid, and sulfuric-acid (7664939). They are corrosive in any form and can cause severe burns on contact with the skin, eyes, lungs, or stomach. Control and preventive measures include good ventilation, use of personal protective equipment, safety showers, eye baths, and stringent personal hygiene. The usual shipping containers must include careful inspection and labeling. Special precautions for storage are mandatory, and it is also important that acids not be transferred from their original container to an unmarked container. Labels should list the name of the product, the degree of hazard, the type of hazard, precautionary measures, and instructions in case of contact or exposure. Since these acids are widely used within industry, they are also one of the most widespread industrial wastes. Small amounts of acid may be disposed of by dilution and neutralization. Larger amounts require a larger system of waste disposal. If an individual comes in contact with a hazardous substance, removal from exposure is primary, and the ready availability of water will minimize severe damage. Appendices include a table of physical and chemical properties for the inorganic acids, a list of emergency procedures, a sample safety poster, and 12 references.","The Inorganic Acids Abs: The properties and characteristics of the common commercial forms of inorganic acids are discussed. An inorganic acid is a compound of hydrogen and one or more elements (except carbon), which dissociates or breaks down to produce hydrogen ions when dissolved in water or a solvent liquid. The most common inorganic acids used in industry are chromium-trioxide, hydrochloric-acid (7647010), hydrogen-fluoride (7664393), nitric-acid (7697372), perchloric-acid (7601903), orthophosphoric-acid, and sulfuric-acid (7664939). They are corrosive in any form and can cause severe burns on contact with the skin, eyes, lungs, or stomach. Control and preventive measures include good ventilation, use of personal protective equipment, safety showers, eye baths, and stringent personal hygiene. The usual shipping containers must include careful inspection and labeling. Special precautions for storage are mandatory, and it is also important that acids not be transferred from their original container to an unmarked container. Labels should list the name of the product, the degree of hazard, the type of hazard, precautionary measures, and instructions in case of contact or exposure. Since these acids are widely used within industry, they are also one of the most widespread industrial wastes. Small amounts of acid may be disposed of by dilution and neutralization. Larger amounts require a larger system of waste disposal. If an individual comes in contact with a hazardous substance, removal from exposure is primary, and the ready availability of water will minimize severe damage. Appendices include a table of physical and chemical properties for the inorganic acids, a list of emergency procedures, a sample safety poster, and 12 references."
1237910,Casarett et al. 1971,Pulmonary Cell Responses to Metallic Oxides,"Variables in rat pulmonary phagocytic response to metal oxides were studied in-vitro. Sprague-Dawley-rat lungs were lavaged with physiological saline. The fluid was withdrawn and centrifuged. The cells were resuspended in saline. The metallic oxides were suspended in saline and allowed to settle. Particles remaining in suspension were decanted and sonicated. Pulmonary cells and metal oxides were incubated at 37 degrees-C. Cell smears were stained and random counts made to obtain an index of phagocytosis. A concentration of 0.001 molar (M) divalent calcium ion was necessary for peak phagocytosis, as seen with manganese-dioxide (1313139) and chromic-oxide (1308389). Calcium ion concentration did not affect phagocytosis of ferric-oxide (1309371). Retention of the initial saline wash solution increased phagocytosis. The phagocytic index decreased linearly with fractional dilutions of the metal oxide suspension. As the particle to cell ratio increased, the phagocytic index increased linearly up to a ratio of 10, when the index leveled off. The interrelation of silicon-dioxide (7631869) concentration with calcium ion dependency at particle to cell ratios of 10 and above showed a striking increase in the effect of calcium ion after 40 to 60 minutes of incubation. Divalent uranium-oxide (1344576) at a concentration of 0.000001M markedly increased chromic-oxide phagocytosis over 20 minute incubation, but decreased phagocytosis for 40 or 60 minute incubation. Higher concentrations of uranium-dioxide were needed to affect ferric-oxide phagocytosis in the presence of calcium ion. Polyamino-acids, represented by polylysine, also enhance phagocytosis of metal oxides, represented by chromic-oxide. The authors conclude that the indices measured have direct bearing on maintaining pulmonary functional integrity during chronic inhalation of metal oxides from occupational sources or environmental contamination.","Pulmonary Cell Responses to Metallic Oxides Abs: Variables in rat pulmonary phagocytic response to metal oxides were studied in-vitro. Sprague-Dawley-rat lungs were lavaged with physiological saline. The fluid was withdrawn and centrifuged. The cells were resuspended in saline. The metallic oxides were suspended in saline and allowed to settle. Particles remaining in suspension were decanted and sonicated. Pulmonary cells and metal oxides were incubated at 37 degrees-C. Cell smears were stained and random counts made to obtain an index of phagocytosis. A concentration of 0.001 molar (M) divalent calcium ion was necessary for peak phagocytosis, as seen with manganese-dioxide (1313139) and chromic-oxide (1308389). Calcium ion concentration did not affect phagocytosis of ferric-oxide (1309371). Retention of the initial saline wash solution increased phagocytosis. The phagocytic index decreased linearly with fractional dilutions of the metal oxide suspension. As the particle to cell ratio increased, the phagocytic index increased linearly up to a ratio of 10, when the index leveled off. The interrelation of silicon-dioxide (7631869) concentration with calcium ion dependency at particle to cell ratios of 10 and above showed a striking increase in the effect of calcium ion after 40 to 60 minutes of incubation. Divalent uranium-oxide (1344576) at a concentration of 0.000001M markedly increased chromic-oxide phagocytosis over 20 minute incubation, but decreased phagocytosis for 40 or 60 minute incubation. Higher concentrations of uranium-dioxide were needed to affect ferric-oxide phagocytosis in the presence of calcium ion. Polyamino-acids, represented by polylysine, also enhance phagocytosis of metal oxides, represented by chromic-oxide. The authors conclude that the indices measured have direct bearing on maintaining pulmonary functional integrity during chronic inhalation of metal oxides from occupational sources or environmental contamination."
1237908,Manning 1984,FLUID BED CATALYTIC OXIDATION: AN UNDERDEVELOPED HAZARDOUS WASTE TECHNOLOGY,"HMTC The catalytic oxidation kinetics of chlorinated hydrocarbons are determined in an externally pumped recycle reactor with a chromia-alumina catalyst. The oxidation rates are first order for chlorocarbons and fluctuate between zero and first order for oxygen. The reaction rates are slightly inhibited by water. The reduced temperature requirements using the catalytic oxidation process has economic advantages, but could have limited potential in large scale commercial waste disposal facilities due to the presence of dissolved inorganic solids. The process is better suited for the chemical process industry where waste is treated onsite and where waste streams are less variable in composition and volume. Graphs and diagrams are provided. (17 ref.)","FLUID BED CATALYTIC OXIDATION: AN UNDERDEVELOPED HAZARDOUS WASTE TECHNOLOGY Abs: HMTC The catalytic oxidation kinetics of chlorinated hydrocarbons are determined in an externally pumped recycle reactor with a chromia-alumina catalyst. The oxidation rates are first order for chlorocarbons and fluctuate between zero and first order for oxygen. The reaction rates are slightly inhibited by water. The reduced temperature requirements using the catalytic oxidation process has economic advantages, but could have limited potential in large scale commercial waste disposal facilities due to the presence of dissolved inorganic solids. The process is better suited for the chemical process industry where waste is treated onsite and where waste streams are less variable in composition and volume. Graphs and diagrams are provided. (17 ref.)"
1237905,Sertoli et al. 1984,Investigations on the chromium linking with leukocytes,"HEEP COPYRIGHT: BIOL ABS. Patients (63) with allergic contact dermatitis and sensitized to potassium dichromate and 76 non-allergic control subjects were studied. Whether leukocytes (separated in emagel), mononuclear cells (separated in lymphoprep) and T-lymphocytes (separated through rosettes with neuraminidase) bind 51Cr, whether this binding depends on the valence (Cr3+ and Cr6+) and on the type of cells and whether it is conditioned by the hypersensitivity were investigated. Incubation of the cells with the tracer at different times demonstrated that the binding takes place, it depends on the valence and, in certain conditions it is greater for the mononuclear cells and the T-lymphocytes in allergic subjects.","Investigations on the chromium linking with leukocytes Abs: HEEP COPYRIGHT: BIOL ABS. Patients (63) with allergic contact dermatitis and sensitized to potassium dichromate and 76 non-allergic control subjects were studied. Whether leukocytes (separated in emagel), mononuclear cells (separated in lymphoprep) and T-lymphocytes (separated through rosettes with neuraminidase) bind 51Cr, whether this binding depends on the valence (Cr3+ and Cr6+) and on the type of cells and whether it is conditioned by the hypersensitivity were investigated. Incubation of the cells with the tracer at different times demonstrated that the binding takes place, it depends on the valence and, in certain conditions it is greater for the mononuclear cells and the T-lymphocytes in allergic subjects."
1237904,Hermens et al. 1984,Joint effects of a mixture of 14 chemicals on mortality and inhibition of reproduction of Daphnia magna,"HEEP COPYRIGHT: BIOL ABS. The toxicity to D. magna of a mixture of 14 aquatic pollutants with several chemical structures and probable modes of action was determined. The joint effect of this mixture on acute mortality was compared with the effects on inhibition of reproduction. The joint toxicity in the reproduction test was lower in comparison with the mortality test. This study supported the idea that the potential for addition was reduced when more specific sublethal toxicity criteria were studied. Although the joint toxicity at sublethal level was lower than at lethal level, the toxicity of the mixtures remained higher than that of the individual chemicals and was still near concentration addition.","Joint effects of a mixture of 14 chemicals on mortality and inhibition of reproduction of Daphnia magna Abs: HEEP COPYRIGHT: BIOL ABS. The toxicity to D. magna of a mixture of 14 aquatic pollutants with several chemical structures and probable modes of action was determined. The joint effect of this mixture on acute mortality was compared with the effects on inhibition of reproduction. The joint toxicity in the reproduction test was lower in comparison with the mortality test. This study supported the idea that the potential for addition was reduced when more specific sublethal toxicity criteria were studied. Although the joint toxicity at sublethal level was lower than at lethal level, the toxicity of the mixtures remained higher than that of the individual chemicals and was still near concentration addition."
1237900,Van Joost et al. 1984,Shifts of delayed immune response to persulfates and other allergens,"HEEP COPYRIGHT: BIOL ABS. Certain chemicals such as persulfates and formaldehyde are able to induce both immediate and delayed type reactions in the skin. The levels of delayed type response to persulfates (at 48 and 74 h), obtained by epicutaneous tests were subjected to comparative studies of shifts (48 vs. 72 h) and statistical analysis. The 95% confidence limit of the mean value of shifts to persulfates was significantly higher than that of a standard routine battery as a whole and, with the exception of formaldehyde, also to that of other individual consitutents of this battery. In the case of persulfates, this difference in shifts was due to an extremely low mean value of delayed-type response read at 48 h. The possible underlying mechanisms and the possible limiting role of vasoactive amines in the early evolution of delayed-type response is discussed.","Shifts of delayed immune response to persulfates and other allergens Abs: HEEP COPYRIGHT: BIOL ABS. Certain chemicals such as persulfates and formaldehyde are able to induce both immediate and delayed type reactions in the skin. The levels of delayed type response to persulfates (at 48 and 74 h), obtained by epicutaneous tests were subjected to comparative studies of shifts (48 vs. 72 h) and statistical analysis. The 95% confidence limit of the mean value of shifts to persulfates was significantly higher than that of a standard routine battery as a whole and, with the exception of formaldehyde, also to that of other individual consitutents of this battery. In the case of persulfates, this difference in shifts was due to an extremely low mean value of delayed-type response read at 48 h. The possible underlying mechanisms and the possible limiting role of vasoactive amines in the early evolution of delayed-type response is discussed."
1237899,Thompson and  Watling 1984,COMPARATIVE STUDY OF THE TOXICITY OF METAL COMPOUNDS TO HETEROTROPHIC BACTERIA,HEEP COPYRIGHT: BIOL ABS. RRM ESCHERICHIA-COLI METAL POLLUTION GROWTH,COMPARATIVE STUDY OF THE TOXICITY OF METAL COMPOUNDS TO HETEROTROPHIC BACTERIA Abs: HEEP COPYRIGHT: BIOL ABS. RRM ESCHERICHIA-COLI METAL POLLUTION GROWTH
1237897,Susa 1984,Antagonistic effect of DL penicillamine on chromium toxicity in HeLa cells,"The effects of various chelating agents on the cytotoxicity induced by hexavalent chromium, potassium dichromate, were examined. HeLa cells were incubated in Eagle's minimum essential medium (MEM) with or without the chromate alone, or both chromate and any one of DL-penicillamine, glutathione (reduced and oxidized form), L-cysteine, 2, 3-dimercapto-1-propanol (BAL) and ethylene-diaminetetra-acetic acid (2Na-EDTA and 2Na·Ca-EDTA). After a given period of incubation, cell growth and the amount of chromium in the cells were measured. The results obtained were as follows. 1) The growth of HeLa cells in MEM with 3.4 ?M chromate at 3 days of incubation was approximately 15% of that of the control cells. The growth of HeLa cells in MEM containing 3.4 ?M chromate and 670.2 ?M DL-penicillamine was 96%. However, no remarkable antagonism against the chromate toxicity was induced by 0.3 to 325.4 ?M reduced glutathione, 0.2 to 163.2 ?M oxidized glutathione, 0.6 to 56.9 ?M L-cysteine, 0.8 to 8.1 ?M BAL, 0.3 to 268.6 ?M 2Na-EDTA, 0.2 to 224.0 ?M 2Na·Ca-EDTA. 2) DL-penicillamine could not restore the cell growth inhibited by a preincubation in MEM with 3.4 ?M chromate for 6 or 24 hours. 3) The chromium content (as Cr) of HeLa cells in MEM with 3.4 ?M chromate at 6 hours of incubation was 0.148 ?g/106 cells. When 670.2 ?M DL-penicillamine was added to MEM containing 3.4 ?M chromate, the chromium content decreased to 0.0141?g/106 cells (70% reduction). Other chelating agents, 325.4 ?M reduced glutathione, 569.3 ?M L-cysteine and 805.2 ?M BAL, also remarkably reduced the chromium content. However, 163.2 ?M oxidized glutathione, 268.6 ?M 2Na-EDTA and 224.0 ?M 2Na·Ca-EDTA did not reduce the chromium content. These results suggest that DL-penicillamine might inhibit the chromium uptake by HeLa cells and thus prevent the chromium-induced cytotoxicity.","Antagonistic effect of DL penicillamine on chromium toxicity in HeLa cells Abs: The effects of various chelating agents on the cytotoxicity induced by hexavalent chromium, potassium dichromate, were examined. HeLa cells were incubated in Eagle's minimum essential medium (MEM) with or without the chromate alone, or both chromate and any one of DL-penicillamine, glutathione (reduced and oxidized form), L-cysteine, 2, 3-dimercapto-1-propanol (BAL) and ethylene-diaminetetra-acetic acid (2Na-EDTA and 2Na·Ca-EDTA). After a given period of incubation, cell growth and the amount of chromium in the cells were measured. The results obtained were as follows. 1) The growth of HeLa cells in MEM with 3.4 ?M chromate at 3 days of incubation was approximately 15% of that of the control cells. The growth of HeLa cells in MEM containing 3.4 ?M chromate and 670.2 ?M DL-penicillamine was 96%. However, no remarkable antagonism against the chromate toxicity was induced by 0.3 to 325.4 ?M reduced glutathione, 0.2 to 163.2 ?M oxidized glutathione, 0.6 to 56.9 ?M L-cysteine, 0.8 to 8.1 ?M BAL, 0.3 to 268.6 ?M 2Na-EDTA, 0.2 to 224.0 ?M 2Na·Ca-EDTA. 2) DL-penicillamine could not restore the cell growth inhibited by a preincubation in MEM with 3.4 ?M chromate for 6 or 24 hours. 3) The chromium content (as Cr) of HeLa cells in MEM with 3.4 ?M chromate at 6 hours of incubation was 0.148 ?g/106 cells. When 670.2 ?M DL-penicillamine was added to MEM containing 3.4 ?M chromate, the chromium content decreased to 0.0141?g/106 cells (70% reduction). Other chelating agents, 325.4 ?M reduced glutathione, 569.3 ?M L-cysteine and 805.2 ?M BAL, also remarkably reduced the chromium content. However, 163.2 ?M oxidized glutathione, 268.6 ?M 2Na-EDTA and 224.0 ?M 2Na·Ca-EDTA did not reduce the chromium content. These results suggest that DL-penicillamine might inhibit the chromium uptake by HeLa cells and thus prevent the chromium-induced cytotoxicity."
1237895,Christensen and  Nyholm 1984,Ecotoxicological assays with algae: Weibull dose-response curves,"HEEP COPYRIGHT: BIOL ABS. A newly proposed Weibull model was compared to the probit and logit models for the growth rate of algae in natural waters and in wastewater treatment plants as a function of the concentration of metallic and organic toxicants. Four batch assays with Selenastrum capricornutum exposed to potassium dichromate and Cu and with Scenedesmus subscpicatus affected by 3,5-dichlorophenol and potassium dichromate were carried out. Literature data for 4 other experiments were also examined. The data fitting was based on linear transformations of the 3 models using proper weighting. The Weibull model was at least as appropriate as the probit and logit models. The effective concentrations giving 10 and 90% growth rate reduction, EC10 and EC90, were generally lowest for the Weibull model. The slopes (0.5 to 3-5) in the Weibull and logit transformations may be interpreted as the number of toxicant molecules reacting/active receptor of the organism.","Ecotoxicological assays with algae: Weibull dose-response curves Abs: HEEP COPYRIGHT: BIOL ABS. A newly proposed Weibull model was compared to the probit and logit models for the growth rate of algae in natural waters and in wastewater treatment plants as a function of the concentration of metallic and organic toxicants. Four batch assays with Selenastrum capricornutum exposed to potassium dichromate and Cu and with Scenedesmus subscpicatus affected by 3,5-dichlorophenol and potassium dichromate were carried out. Literature data for 4 other experiments were also examined. The data fitting was based on linear transformations of the 3 models using proper weighting. The Weibull model was at least as appropriate as the probit and logit models. The effective concentrations giving 10 and 90% growth rate reduction, EC10 and EC90, were generally lowest for the Weibull model. The slopes (0.5 to 3-5) in the Weibull and logit transformations may be interpreted as the number of toxicant molecules reacting/active receptor of the organism."
1237894,Moller et al. 1984,DELAYED ANAPHYLACTOID REACTION TO INHALED SODIUM CHROMATE,HEEP COPYRIGHT: BIOL ABS. RRM ABSTRACT HUMAN CELL MEDIATED IMMUNITY OVER EXPOSURE SKIN IRRITATION EYE IRRITATION,DELAYED ANAPHYLACTOID REACTION TO INHALED SODIUM CHROMATE Abs: HEEP COPYRIGHT: BIOL ABS. RRM ABSTRACT HUMAN CELL MEDIATED IMMUNITY OVER EXPOSURE SKIN IRRITATION EYE IRRITATION
1237892,Baggett and  Berndt 1984,THE EFFECT OF POTASSIUM DI CHROMATE TO POTENTIATE THE NEPHRO TOXICITY OF MERCURIC CHLORIDE,HEEP COPYRIGHT: BIOL ABS. RRM ABSTRACT TOXICO KINETICS METAL TOXICITY,THE EFFECT OF POTASSIUM DI CHROMATE TO POTENTIATE THE NEPHRO TOXICITY OF MERCURIC CHLORIDE Abs: HEEP COPYRIGHT: BIOL ABS. RRM ABSTRACT TOXICO KINETICS METAL TOXICITY
1237891,Van Weerelt et al. 1984,Uptake and release of chromium-51(VI) and chromium-51(III) by barnacles (Balanus sp.),"HEEP COPYRIGHT: BIOL ABS. Barnacles (Balanus sp.) were used to examine the uptake and release of 51Cr added to sea water in 2 different valence states, 51Cr(VI) and 51Cr(III). 51Cr (VI) (sodium chromate) formed a true ionic solution in filtered seawater and barnacles accumulated Cr in soft tissues 543-fold the levels found in seawater. Incorporated Cr(VI) was released to the water in such way that only 20% of maximum uptake was lost by the organisms after 26 days. Addition of the hexavalent form to nonfiltered seawater showed that 2% of the total radioactivity was attached to the suspended particles. Cr was mainly concentrated in soft tissues, showing a concentration factor of 380 related to total Cr available in aquarium (solution + suspended particles). From the total radioactivity incorporated by the organisms, 20% was released after 56 days in the clearance experiment. Cr, as trivalent chromic chloride, when added to seawater precipitated and was quickly removed from the water by the filter activity of the barnacles. Unlike Cr (VI), Cr (III) was not concentrated in soft tissues of the barnacles and was quickly released to the water through the digestive system.","Uptake and release of chromium-51(VI) and chromium-51(III) by barnacles (Balanus sp.) Abs: HEEP COPYRIGHT: BIOL ABS. Barnacles (Balanus sp.) were used to examine the uptake and release of 51Cr added to sea water in 2 different valence states, 51Cr(VI) and 51Cr(III). 51Cr (VI) (sodium chromate) formed a true ionic solution in filtered seawater and barnacles accumulated Cr in soft tissues 543-fold the levels found in seawater. Incorporated Cr(VI) was released to the water in such way that only 20% of maximum uptake was lost by the organisms after 26 days. Addition of the hexavalent form to nonfiltered seawater showed that 2% of the total radioactivity was attached to the suspended particles. Cr was mainly concentrated in soft tissues, showing a concentration factor of 380 related to total Cr available in aquarium (solution + suspended particles). From the total radioactivity incorporated by the organisms, 20% was released after 56 days in the clearance experiment. Cr, as trivalent chromic chloride, when added to seawater precipitated and was quickly removed from the water by the filter activity of the barnacles. Unlike Cr (VI), Cr (III) was not concentrated in soft tissues of the barnacles and was quickly released to the water through the digestive system."
1237890,Zakour and  Glickman 1984,Metal-induced mutagenesis in the lacI gene of Escherichia coli,"HEEP COPYRIGHT: BIOL ABS. Mutagenesis in the lacI gene of E. coli was examined in cells grown in the presence of Be, Mn or Cr compounds, metals with suspected mutagenic or carcinogenic potential; 2- to 3-fold increases in mutation frequency were produced by BeCl2, MnCl2 and K2Cr2O7. Among the cells grown in the presence of Be2+, the frequency of amber and ochre mutants was 3-fold higher than the spontaneous background, suggesting that at least part of the increased mutagenicity was due to base-substitution mutations. The specificity of base-substitution mutations induced by Be2+ and Mn2+ in the lacI gene was analyzed. Among the amber mutations induced in cells grown in the presence of Be2+, an increase in G:C - A:T transitions was detected. Following growth in Mn2+ no increase in amber and ochre mutation frequencies was observed and the mutational spectrum resembled that obtained spontaneously, indicating that mutations induced by Mn2+ in the lacI gene involve changes that do not yield nonsense mutations. Metals may exert a number of different mutagenic effects and these effects vary for each metal.","Metal-induced mutagenesis in the lacI gene of Escherichia coli Abs: HEEP COPYRIGHT: BIOL ABS. Mutagenesis in the lacI gene of E. coli was examined in cells grown in the presence of Be, Mn or Cr compounds, metals with suspected mutagenic or carcinogenic potential; 2- to 3-fold increases in mutation frequency were produced by BeCl2, MnCl2 and K2Cr2O7. Among the cells grown in the presence of Be2+, the frequency of amber and ochre mutants was 3-fold higher than the spontaneous background, suggesting that at least part of the increased mutagenicity was due to base-substitution mutations. The specificity of base-substitution mutations induced by Be2+ and Mn2+ in the lacI gene was analyzed. Among the amber mutations induced in cells grown in the presence of Be2+, an increase in G:C - A:T transitions was detected. Following growth in Mn2+ no increase in amber and ochre mutation frequencies was observed and the mutational spectrum resembled that obtained spontaneously, indicating that mutations induced by Mn2+ in the lacI gene involve changes that do not yield nonsense mutations. Metals may exert a number of different mutagenic effects and these effects vary for each metal."
1237887,Bubien et al. 1983,Electron microscopic studies on enterocytes of hens intoxicated with potassium dichromate,"HEEP COPYRIGHT: BIOL ABS. Advanced necrotic changes in the ultrastructures of enterocytes were observed in hens intoxicated with K2Cr2O7. Destruction of mitochondria, breaking of the cellular coating of enterocytes with outflow of cytoplasm and its structures into the lumen of the intestine were found. Twenty days after intoxication no pathological changes were observed.","Electron microscopic studies on enterocytes of hens intoxicated with potassium dichromate Abs: HEEP COPYRIGHT: BIOL ABS. Advanced necrotic changes in the ultrastructures of enterocytes were observed in hens intoxicated with K2Cr2O7. Destruction of mitochondria, breaking of the cellular coating of enterocytes with outflow of cytoplasm and its structures into the lumen of the intestine were found. Twenty days after intoxication no pathological changes were observed."
1237886,Cantoni and  Costa 1983,DIFFERENTIATION OF ALKALINE SENSITIVE SITES AND SINGLE STRAND BREAKS IN THE DNA FROM MAMMALIAN CELLS TREATED WITH CALCIUM CHROMATE MERCURIC CHLORITE N METHYL-N-NITROSO UREA AND X-RAYS,HEEP COPYRIGHT: BIOL ABS. RRM ABSTRACT CHINESE HAMSTER OVARY CELL DNA PROTEIN CROSS LINK,DIFFERENTIATION OF ALKALINE SENSITIVE SITES AND SINGLE STRAND BREAKS IN THE DNA FROM MAMMALIAN CELLS TREATED WITH CALCIUM CHROMATE MERCURIC CHLORITE N METHYL-N-NITROSO UREA AND X-RAYS Abs: HEEP COPYRIGHT: BIOL ABS. RRM ABSTRACT CHINESE HAMSTER OVARY CELL DNA PROTEIN CROSS LINK
1237884,Schoenert et al. 1983,THE SENSITIVITY OF 6 STRAINS OF UNI CELLULAR ALGAE SELENASTRUM-CAPRICORNUTUM TO 6 REFERENCE TOXICANTS,HEEP COPYRIGHT: BIOL ABS. RRM BIO MONITORING WATER POLLUTION,THE SENSITIVITY OF 6 STRAINS OF UNI CELLULAR ALGAE SELENASTRUM-CAPRICORNUTUM TO 6 REFERENCE TOXICANTS Abs: HEEP COPYRIGHT: BIOL ABS. RRM BIO MONITORING WATER POLLUTION
1237882,Mitchell et al. 1983,Uscheduled DNA synthesis test a report of the USA Environmental Protection Agency gene-tox program,HEEP COPYRIGHT: BIOL ABS. RRM HUMAN DI PLOID FIBROBLAST RAT HEPATOCYTE MUTAGEN CARCINOGEN,Uscheduled DNA synthesis test a report of the USA Environmental Protection Agency gene-tox program Abs: HEEP COPYRIGHT: BIOL ABS. RRM HUMAN DI PLOID FIBROBLAST RAT HEPATOCYTE MUTAGEN CARCINOGEN
1237880,Mcfeters et al. 1983,A comparison of microbial bioassays for the detection of aquatic toxicants,"HEEP COPYRIGHT: BIOL ABS. The toxicity of 35 test chemicals was analyzed using 2 microbial bioassay systems. The commercially available Microtox toxicity analyzer system and the 2-organism procedure of Tchan were used to determine the concentration of test chemicals resulting in a 50% reduction in response (EC50). Both tests employed a luminescent bacterium while the procedure of Tchan also utilized an alga. Results from the 2 microbial tests were compared with available data obtained with fish toxicity bioassays and with each other. The Microtox procedure was more sensitive than the Tchan bioassay in detecting most test chemicals and fish bioassays were generally more sensitive than either microbial test. As notable exception, photosynthesis-inhibiting herbicides were detected at remarkably lower concentrations with the procedure of Tchan than any other bioassay. Potential applications for these tests were discussed.","A comparison of microbial bioassays for the detection of aquatic toxicants Abs: HEEP COPYRIGHT: BIOL ABS. The toxicity of 35 test chemicals was analyzed using 2 microbial bioassay systems. The commercially available Microtox toxicity analyzer system and the 2-organism procedure of Tchan were used to determine the concentration of test chemicals resulting in a 50% reduction in response (EC50). Both tests employed a luminescent bacterium while the procedure of Tchan also utilized an alga. Results from the 2 microbial tests were compared with available data obtained with fish toxicity bioassays and with each other. The Microtox procedure was more sensitive than the Tchan bioassay in detecting most test chemicals and fish bioassays were generally more sensitive than either microbial test. As notable exception, photosynthesis-inhibiting herbicides were detected at remarkably lower concentrations with the procedure of Tchan than any other bioassay. Potential applications for these tests were discussed."
1237879,Conklin et al. 1983,Comparative toxicity of drilling muds: Role of chromium and petroleum hydrocarbons,"HEEP COPYRIGHT: BIOL ABS. Samples of used drilling muds collected during the course of a single well drilling operation exhibited different degrees of acute toxicity to sheepshead minnows and grass shrimp. For molting grass shrimp, Palaemonetes pugio, the 96 h LC50 were 360-14,560 ppm (mul/l); many of these values were lower than those reported from previous drilling mud assays. When some muds were tested on sheepshead minnows, Cyprinodon variegatus, the resulting 96 h LC50 (6300-100,000 ppm) were well within the range of previously reported values. Although a number of the drilling mud samples had relatively high amounts of Cr due to the addition of sodium chromate, there was a lower correlation between Cr concentration and toxicity. In only 3 drilling muds could Cr content alone account for the observed toxicities. Chemical analyses revealed the presence of No. 2 fuel oil-like petroleum hydrocarbons in the mud samples. Based on the results of toxicity tests with No. 2 fuel oil and the concentrations of oil present in the muds, the toxicity of the mud samples to grass shrimp appeared to be largely attributable to the petroleum hydrocarbon content.","Comparative toxicity of drilling muds: Role of chromium and petroleum hydrocarbons Abs: HEEP COPYRIGHT: BIOL ABS. Samples of used drilling muds collected during the course of a single well drilling operation exhibited different degrees of acute toxicity to sheepshead minnows and grass shrimp. For molting grass shrimp, Palaemonetes pugio, the 96 h LC50 were 360-14,560 ppm (mul/l); many of these values were lower than those reported from previous drilling mud assays. When some muds were tested on sheepshead minnows, Cyprinodon variegatus, the resulting 96 h LC50 (6300-100,000 ppm) were well within the range of previously reported values. Although a number of the drilling mud samples had relatively high amounts of Cr due to the addition of sodium chromate, there was a lower correlation between Cr concentration and toxicity. In only 3 drilling muds could Cr content alone account for the observed toxicities. Chemical analyses revealed the presence of No. 2 fuel oil-like petroleum hydrocarbons in the mud samples. Based on the results of toxicity tests with No. 2 fuel oil and the concentrations of oil present in the muds, the toxicity of the mud samples to grass shrimp appeared to be largely attributable to the petroleum hydrocarbon content."
1237876,Cravedi et al. 1983,Digestibility of saturated hydrocarbons in the trout (Salmo gairdneri),"HEEP COPYRIGHT: BIOL ABS. The digestibility of alkanes was investigated in rainbow trout S. gairdneri using an indicator method, based on the utilization of chromic oxide as a marker. Fish were fed experimental diets containing 1% pristane, dodecylcyclohexane or a mixture of n-paraffins (from C14-C20 plus C24). Feces were collected automatically during 7 days. The absorption of n-alkanes in trout followed a parabolic relationship with C chain length. The maximum digestibility was observed for pentadecane. For the same total C number, straight-chain saturated hydrocarbons were preferentially retained over cycloalkanes but less absorbed than branched-paraffins.","Digestibility of saturated hydrocarbons in the trout (Salmo gairdneri) Abs: HEEP COPYRIGHT: BIOL ABS. The digestibility of alkanes was investigated in rainbow trout S. gairdneri using an indicator method, based on the utilization of chromic oxide as a marker. Fish were fed experimental diets containing 1% pristane, dodecylcyclohexane or a mixture of n-paraffins (from C14-C20 plus C24). Feces were collected automatically during 7 days. The absorption of n-alkanes in trout followed a parabolic relationship with C chain length. The maximum digestibility was observed for pentadecane. For the same total C number, straight-chain saturated hydrocarbons were preferentially retained over cycloalkanes but less absorbed than branched-paraffins."
1237875,Slooff and  Canton 1983,Comparison of the susceptibility of 11 freshwater species to 8 chemical compounds: 2. (Semi)chronic toxicity tests,"HEEP COPYRIGHT: BIOL ABS. The relative susceptibility of 11 taxonomically different species (Pseudomonas fluorescens, Microcystis aeruginosa, Scenedesmus pannonicus, Lemna minor, Daphnia magna, Culex pipiens, Hydra oligactis, Lymnaea stagnalis, Poecilia reticulata, Oryzias latipes, Xenopus laevis) to chemicals was determined by comparing the (semi)chronic toxicity data of 8 test substances (NaBr, K2Cr2O7, p-nitrotoluene, dinitro-o-cresol, dimethoate, pentachlorophenol, tetrapropylene benzene sulfonate, 2,4-dichloroaniline). Marked differences were observed in the susceptibility among the species with respect to the individual test compounds (up to a factor of 10,000). Differences were smaller (a factor 50) when the relative susceptibility based on all separate toxicity data of the compounds was taken into account. A test set with an alga, a crustacean and an egg-laying fish species generally gave a good impression of the toxic potential of chemicals to aquatic life. The use of data derived from acute and chronic toxicity tests to estimate the impact of chemical substances on aquatic ecosystems was discussed. For most chemicals the difference in short- and long-term toxicity data on the same species was less than the difference in the susceptibility of various species.","Comparison of the susceptibility of 11 freshwater species to 8 chemical compounds: 2. (Semi)chronic toxicity tests Abs: HEEP COPYRIGHT: BIOL ABS. The relative susceptibility of 11 taxonomically different species (Pseudomonas fluorescens, Microcystis aeruginosa, Scenedesmus pannonicus, Lemna minor, Daphnia magna, Culex pipiens, Hydra oligactis, Lymnaea stagnalis, Poecilia reticulata, Oryzias latipes, Xenopus laevis) to chemicals was determined by comparing the (semi)chronic toxicity data of 8 test substances (NaBr, K2Cr2O7, p-nitrotoluene, dinitro-o-cresol, dimethoate, pentachlorophenol, tetrapropylene benzene sulfonate, 2,4-dichloroaniline). Marked differences were observed in the susceptibility among the species with respect to the individual test compounds (up to a factor of 10,000). Differences were smaller (a factor 50) when the relative susceptibility based on all separate toxicity data of the compounds was taken into account. A test set with an alga, a crustacean and an egg-laying fish species generally gave a good impression of the toxic potential of chemicals to aquatic life. The use of data derived from acute and chronic toxicity tests to estimate the impact of chemical substances on aquatic ecosystems was discussed. For most chemicals the difference in short- and long-term toxicity data on the same species was less than the difference in the susceptibility of various species."
1237870,Frenet et al. 1983,In vitro dissolution of metallic oxides in human plasma and metal binding on plasma proteins: Influence of chelating agents,"HEEP COPYRIGHT: BIOL ABS. The solubility in biological liquids of oxides is 1 factor which determines the speed of penetration into the blood stream of toxic substances contained in solid particles inside pulmonary alveoles. This solubility was studied in vitro for the 6 metal oxides: Cd, Cr, Fe, Mn, Pb and Zn, by placing particle oxides in suspension into human plasma at 37? C, during variable times. Particles belonged to 2 size categories, 0.45-2 and 2-5mum. The evolution of metal oxide dissolved level according to time was used to determine exponential relation parameters. These parameters translated the particle oxide dissolution into plasma and were used to classify metal oxides in decreasing solubility order: Cd, Zn, PbO, Fe2O3, Fe3O4, Mn, PbO2, Pb3O4 and Cr2O3. Dissolved metal distribution between the different protein fractions was also studied. Dissolved metal was distributed between diffusible metal (10%) and metal binding proteins chiefly in albumin, except for Fe which was bound to transferrin. Chelating agents in plasma reduced the proportion of metals bound to proteins. EDTA Ca was energetic on all metals, mainly Pb, Cd and Zn. N-acetyl-DL-penicillamine was less energetic. Meso-2,3-dimercaptosuccinic acid and 2,3-dimercapto-1-propanol had a slight effect only on Pb. Desferrioxamine released a great proportion of Fe bound to proteins. These results, obtained in vitro, were similar to those from animal experimentation or those observed in human therapeutic.","In vitro dissolution of metallic oxides in human plasma and metal binding on plasma proteins: Influence of chelating agents Abs: HEEP COPYRIGHT: BIOL ABS. The solubility in biological liquids of oxides is 1 factor which determines the speed of penetration into the blood stream of toxic substances contained in solid particles inside pulmonary alveoles. This solubility was studied in vitro for the 6 metal oxides: Cd, Cr, Fe, Mn, Pb and Zn, by placing particle oxides in suspension into human plasma at 37? C, during variable times. Particles belonged to 2 size categories, 0.45-2 and 2-5mum. The evolution of metal oxide dissolved level according to time was used to determine exponential relation parameters. These parameters translated the particle oxide dissolution into plasma and were used to classify metal oxides in decreasing solubility order: Cd, Zn, PbO, Fe2O3, Fe3O4, Mn, PbO2, Pb3O4 and Cr2O3. Dissolved metal distribution between the different protein fractions was also studied. Dissolved metal was distributed between diffusible metal (10%) and metal binding proteins chiefly in albumin, except for Fe which was bound to transferrin. Chelating agents in plasma reduced the proportion of metals bound to proteins. EDTA Ca was energetic on all metals, mainly Pb, Cd and Zn. N-acetyl-DL-penicillamine was less energetic. Meso-2,3-dimercaptosuccinic acid and 2,3-dimercapto-1-propanol had a slight effect only on Pb. Desferrioxamine released a great proportion of Fe bound to proteins. These results, obtained in vitro, were similar to those from animal experimentation or those observed in human therapeutic."
1237868,Christie et al. 1983,Assessment of metal-induced DNA damage in repair-deficient CHO cells,,Assessment of metal-induced DNA damage in repair-deficient CHO cells Abs: 
1237865,Majone et al. 1983,Sister chromatid exchanges induced in vivo and in vitro by chemical carcinogens in mouse lymphocytes carrying endogenized Moloney leukemia virus,"The induction of sister chromatid exchanges (SCEs) was analysed in mouse spleen T lymphocytes treated in vivo or in vitro with chemical carcinogens. Lymphocytes were obtained from BALB/Mo mice, which carry the Moloney murine leukemia virus (M-MuLV) as endogenous type C retrovirus, and from control BALB/c mice (M-MuLV free). SCEs were determined in vitro on lymphocytes stimulated with con-canavalin A (Con A) and incubated for two generation cycles with bromodeoxyuridine (BUdR). The baseline frequency of SCEs in untreated lymphocytes obtained from 2–3 month old and 4 day old BALB/Mo mice was significantly higher when compared with that observed in control BALB/c lymphocytes. Treatments in vitro with 10?6 M hexavalent chromium (Cr(VI)( as potassium dichromate) and 10?7 M, or 3 × 10?7 M mitomycin C (MMC) increased the SCE frequency in BALB/c lymphocytes, even more in BALB/Mo lymphocytes, indicating that M-MuLV and chemical carcinogens interacted synergistically in inducing SCEs in the presence of BUdR. On the other hand, the frequencies of SCEs in either BALB/c or BALB/Mo lymphocytes were not modified by treatment in vitro with 10?3 M trivalent chromium (Cr(III), as chromium chloride), which is genetically inactive. Treatment in vivo with 0.3 mg/kg MMC or 1 mg/g urethane followed by incubation in vitro with BUdR in the absence of the carcinogens produced only additive effects on BALB/Mo lymphocytes. The same was observed when unstimulated BALB/Mo lymphocytes were treated in vitro with MMC in the absence of BUdR, and then stimulated and incubated with BUdR but not with MMC. Treatment in vivo with a high dose of MMC (10 mg/kg), produced negative synergistic effects on the induction of SCEs in BALB/Mo lymphocytes. The different interaction of M-MuLV and chemicals on the induction of SCEs was interpreted in terms of positive or negative interference of the oncogenic virus and chemical carcinogens with the functions of enzymes, such as DNA topoisomerases, involved in the mechanism of SCE production, and was tentatively ascribed to the presence of larger DNA replicons in BALB/Mo than in BALB/c lymphocytes.","Sister chromatid exchanges induced in vivo and in vitro by chemical carcinogens in mouse lymphocytes carrying endogenized Moloney leukemia virus Abs: The induction of sister chromatid exchanges (SCEs) was analysed in mouse spleen T lymphocytes treated in vivo or in vitro with chemical carcinogens. Lymphocytes were obtained from BALB/Mo mice, which carry the Moloney murine leukemia virus (M-MuLV) as endogenous type C retrovirus, and from control BALB/c mice (M-MuLV free). SCEs were determined in vitro on lymphocytes stimulated with con-canavalin A (Con A) and incubated for two generation cycles with bromodeoxyuridine (BUdR). The baseline frequency of SCEs in untreated lymphocytes obtained from 2–3 month old and 4 day old BALB/Mo mice was significantly higher when compared with that observed in control BALB/c lymphocytes. Treatments in vitro with 10?6 M hexavalent chromium (Cr(VI)( as potassium dichromate) and 10?7 M, or 3 × 10?7 M mitomycin C (MMC) increased the SCE frequency in BALB/c lymphocytes, even more in BALB/Mo lymphocytes, indicating that M-MuLV and chemical carcinogens interacted synergistically in inducing SCEs in the presence of BUdR. On the other hand, the frequencies of SCEs in either BALB/c or BALB/Mo lymphocytes were not modified by treatment in vitro with 10?3 M trivalent chromium (Cr(III), as chromium chloride), which is genetically inactive. Treatment in vivo with 0.3 mg/kg MMC or 1 mg/g urethane followed by incubation in vitro with BUdR in the absence of the carcinogens produced only additive effects on BALB/Mo lymphocytes. The same was observed when unstimulated BALB/Mo lymphocytes were treated in vitro with MMC in the absence of BUdR, and then stimulated and incubated with BUdR but not with MMC. Treatment in vivo with a high dose of MMC (10 mg/kg), produced negative synergistic effects on the induction of SCEs in BALB/Mo lymphocytes. The different interaction of M-MuLV and chemicals on the induction of SCEs was interpreted in terms of positive or negative interference of the oncogenic virus and chemical carcinogens with the functions of enzymes, such as DNA topoisomerases, involved in the mechanism of SCE production, and was tentatively ascribed to the presence of larger DNA replicons in BALB/Mo than in BALB/c lymphocytes."
1237858,Rajendrababu and  Kumar 1982,Simple paper chromatographic method for rapid determination of chromate(VI) in fresh water,"A simple concentration method for detection of potassium (di)chromate directly in fresh water was described. Interference from acidity, alkalinity or the presence of salt was eliminated by neutralization with phosphate buffer. A simple and sensitive method for potassium chromate or dichromate(VI) separation and detection by paper chromatography was also described. Succinate dehydrogenase inhibition with 2-(4-iodophenyl)-3-(4-nitrophenyl)-5-phenyltetrazolium chloride (INT)-phenazonium methosulfate (PMS)-sodium succinate mixture as the chromogenic reagent was the detection technique. An acetone-water-EDTA solvent system allowed enzymatic detection of potassium (di)chromate in fresh water with the least cleanup effort: 2 mug was detected by a spot test or 5 mug chromatographically detected directly from fresh water.","Simple paper chromatographic method for rapid determination of chromate(VI) in fresh water Abs: A simple concentration method for detection of potassium (di)chromate directly in fresh water was described. Interference from acidity, alkalinity or the presence of salt was eliminated by neutralization with phosphate buffer. A simple and sensitive method for potassium chromate or dichromate(VI) separation and detection by paper chromatography was also described. Succinate dehydrogenase inhibition with 2-(4-iodophenyl)-3-(4-nitrophenyl)-5-phenyltetrazolium chloride (INT)-phenazonium methosulfate (PMS)-sodium succinate mixture as the chromogenic reagent was the detection technique. An acetone-water-EDTA solvent system allowed enzymatic detection of potassium (di)chromate in fresh water with the least cleanup effort: 2 mug was detected by a spot test or 5 mug chromatographically detected directly from fresh water."
1237855,Deknudt 1982,In vivo study of the mutagenicity of heavy metals in mammals,HEEP COPYRIGHT: BIOL ABS. ABSTRACT MOUSE POTASSIUM DI CHROMATE CALCIUM CHROMATE NICKEL NITRATE NICKEL CHLORIDE,In vivo study of the mutagenicity of heavy metals in mammals Abs: HEEP COPYRIGHT: BIOL ABS. ABSTRACT MOUSE POTASSIUM DI CHROMATE CALCIUM CHROMATE NICKEL NITRATE NICKEL CHLORIDE
1237854,Tanaka et al. 1982,Biological tests using the brine shrimp (Artemia salina): 3. The toxicities of metal compounds and the synergistic effects of metal compounds and mycotoxins on the brine shrimp,"HEEP COPYRIGHT: BIOL ABS. Biological tests were carried out on the brine shrimp using metallic compounds and simultaneous administration of mycotoxins and metallic compounds. The survival rate of the brine shrimp was high from pH 6.1-9.0, when examined at various pH using a mixture of artificial sea water (2 parts) and Britton-Robinson buffer (1 part). Cl- and SO42- were less toxic to the brine shrimp compared to metallic ions. Within the 17 metallic compounds examined, the toxicity levels of K2CrO4, K2Cr2O7, CuSO4 and HgCl2 were comparatively high. At toxic level, the pH of the solutions of each metallic compound was measured. pH was low and could have influenced the survival rate of the brine shrimp in the case of CrKO8S2, FeO4S, Fe2O12S3 and FeCl3. The simultaneous administration of half the median tolerance limit (TLm) of 6 mycotoxins and 1 of 7 metallic compounds to the brine shrimp was carried out. A weak synergistic effect was observed with the administration of ochratoxin A (OC-A) and ZnSO4 while comparatively stronger synergistic effects were observed with the administration of OC-A and HgCl2 and aflatoxin B1 and HgCl2. The toxicity level was weakened by the simultaneous administration of sterigmatocystin (ST) and CuSO4. The mean values of the toxicity levels of OC-A when administered simultaneously with CdCl2, K2CrO4 or K2Cr2O7, and ST when administered simultaneously with HgCl2 were lower than the toxicity value of 1/2 TLm of each mycotoxin or metallic compound although the value varied widely. In the case of other mycotoxins and metallic compounds, the levels of toxicity were cumulative.","Biological tests using the brine shrimp (Artemia salina): 3. The toxicities of metal compounds and the synergistic effects of metal compounds and mycotoxins on the brine shrimp Abs: HEEP COPYRIGHT: BIOL ABS. Biological tests were carried out on the brine shrimp using metallic compounds and simultaneous administration of mycotoxins and metallic compounds. The survival rate of the brine shrimp was high from pH 6.1-9.0, when examined at various pH using a mixture of artificial sea water (2 parts) and Britton-Robinson buffer (1 part). Cl- and SO42- were less toxic to the brine shrimp compared to metallic ions. Within the 17 metallic compounds examined, the toxicity levels of K2CrO4, K2Cr2O7, CuSO4 and HgCl2 were comparatively high. At toxic level, the pH of the solutions of each metallic compound was measured. pH was low and could have influenced the survival rate of the brine shrimp in the case of CrKO8S2, FeO4S, Fe2O12S3 and FeCl3. The simultaneous administration of half the median tolerance limit (TLm) of 6 mycotoxins and 1 of 7 metallic compounds to the brine shrimp was carried out. A weak synergistic effect was observed with the administration of ochratoxin A (OC-A) and ZnSO4 while comparatively stronger synergistic effects were observed with the administration of OC-A and HgCl2 and aflatoxin B1 and HgCl2. The toxicity level was weakened by the simultaneous administration of sterigmatocystin (ST) and CuSO4. The mean values of the toxicity levels of OC-A when administered simultaneously with CdCl2, K2CrO4 or K2Cr2O7, and ST when administered simultaneously with HgCl2 were lower than the toxicity value of 1/2 TLm of each mycotoxin or metallic compound although the value varied widely. In the case of other mycotoxins and metallic compounds, the levels of toxicity were cumulative."
1237853,De Moragas et al. 1982,SURGICAL SYMPATHECTOMY IN A CASE OF CONTACT DERMATITIS,HEEP COPYRIGHT: BIOL ABS. HUMAN HAND HYPER HIDROSIS METAL WORKER,SURGICAL SYMPATHECTOMY IN A CASE OF CONTACT DERMATITIS Abs: HEEP COPYRIGHT: BIOL ABS. HUMAN HAND HYPER HIDROSIS METAL WORKER
1237852,Oberly et al. 1982,Mutagenicity of metal salts in the L51784 mouse lymphoma assay,"HEEP COPYRIGHT: BIOL ABS. Metals (11) were examined for their potential to induce forward mutations at the thymidine kinase locus in L5178Y mouse lymphoma cells. The materials tested included AlCl3, CdSO4, HgCl4, K2CrO4, K2Cr2O7, MgCl2, MnCl2, NaAsO2, Na2HAsO4, NaCl and Pb(NO3)2. Strong positive responses at survivals 10% were observed with CdSO4, K2CrO4, K2Cr2O7 and MnCl2. Weak positive responses, yielding 2- to 3-fold increases in mutation frequency above the solvent control at 10% survival, were seen with HgCl2, NaAsO2, Na2HAsO4 and Pb(NO3)2. Negative responses were obtained with MgCl2, NaCl and AlCl3. (This study may be applicable to human carcinogenesis/environmental pollutants.)","Mutagenicity of metal salts in the L51784 mouse lymphoma assay Abs: HEEP COPYRIGHT: BIOL ABS. Metals (11) were examined for their potential to induce forward mutations at the thymidine kinase locus in L5178Y mouse lymphoma cells. The materials tested included AlCl3, CdSO4, HgCl4, K2CrO4, K2Cr2O7, MgCl2, MnCl2, NaAsO2, Na2HAsO4, NaCl and Pb(NO3)2. Strong positive responses at survivals 10% were observed with CdSO4, K2CrO4, K2Cr2O7 and MnCl2. Weak positive responses, yielding 2- to 3-fold increases in mutation frequency above the solvent control at 10% survival, were seen with HgCl2, NaAsO2, Na2HAsO4 and Pb(NO3)2. Negative responses were obtained with MgCl2, NaCl and AlCl3. (This study may be applicable to human carcinogenesis/environmental pollutants.)"
1237850,Berkun 1982,Effects of inorganic metal toxicity on biochemical oxygen demand and methods for the estimation of biochemical oxygen demand parameters,"HEEP COPYRIGHT: BIOL ABS. The effects of HgCl2, HgSO4, K2Cr2O7, CuSO4, ZnSO4 and Al2(SO4)3 on biochemical O2 demand (BOD) were investigated using a respirometer. When these inorganic metal compounds were added to a synthetic medium, respirometric BOD values and batcerial growth in an aeration system were affected. Some new solutions of the 1st order equations for the calculating the rate constant are presented as time saving alternatives to the existing ones. Ultimte BOD values obtained from the 2nd order equation are significantly higher than those produced from the 1st order equation. There is a linear relationship between 1st and 2nd order BOD parameters using crude sewage samples but not when synthetic medium is used.","Effects of inorganic metal toxicity on biochemical oxygen demand and methods for the estimation of biochemical oxygen demand parameters Abs: HEEP COPYRIGHT: BIOL ABS. The effects of HgCl2, HgSO4, K2Cr2O7, CuSO4, ZnSO4 and Al2(SO4)3 on biochemical O2 demand (BOD) were investigated using a respirometer. When these inorganic metal compounds were added to a synthetic medium, respirometric BOD values and batcerial growth in an aeration system were affected. Some new solutions of the 1st order equations for the calculating the rate constant are presented as time saving alternatives to the existing ones. Ultimte BOD values obtained from the 2nd order equation are significantly higher than those produced from the 1st order equation. There is a linear relationship between 1st and 2nd order BOD parameters using crude sewage samples but not when synthetic medium is used."
1237849,Roy and  Mukherji 1982,"Regulation of enzyme activity in mung bean, Phaseolus aureus, seedlings by chromium","HEEP COPYRIGHT: BIOL ABS. The effects of toxic concentrations of potassium dichromate (K2Cr2O7) and Cr2S3O12 on the growth and germination of mung bean P. aureus L. seedlings are reported. These effects included inhibition of hypocotyl elongation and fresh and dry weight increase in the presence of Cr salts, dichromate being relatively more toxic than Cr2S3O12. The activity of catalase, peroxidase, IAA-oxidase, ascorbic acid oxidase and dehydrogenase increased in response to Cr addition. This stimulation of enzyme activity was synchronized with a similar increase in soluble protein formation.","Regulation of enzyme activity in mung bean, Phaseolus aureus, seedlings by chromium Abs: HEEP COPYRIGHT: BIOL ABS. The effects of toxic concentrations of potassium dichromate (K2Cr2O7) and Cr2S3O12 on the growth and germination of mung bean P. aureus L. seedlings are reported. These effects included inhibition of hypocotyl elongation and fresh and dry weight increase in the presence of Cr salts, dichromate being relatively more toxic than Cr2S3O12. The activity of catalase, peroxidase, IAA-oxidase, ascorbic acid oxidase and dehydrogenase increased in response to Cr addition. This stimulation of enzyme activity was synchronized with a similar increase in soluble protein formation."
1237846,Pashin YU and  Kozachenko 1981,MUTAGENIC ACTIVITY OF CHROMIUM COMPOUNDS,HEEP COPYRIGHT: BIOL ABS. REVIEW SALMONELLA-TYPHIMURIUM PLANTS ANIMAL BACTERIA FUNGI MAMMALS WORKERS HUMAN MICE OCCUPATIONAL EXPOSURE ENVIRONMENTAL POLLUTION,MUTAGENIC ACTIVITY OF CHROMIUM COMPOUNDS Abs: HEEP COPYRIGHT: BIOL ABS. REVIEW SALMONELLA-TYPHIMURIUM PLANTS ANIMAL BACTERIA FUNGI MAMMALS WORKERS HUMAN MICE OCCUPATIONAL EXPOSURE ENVIRONMENTAL POLLUTION
1237844,Momokawa et al. 1981,Colorimetric determination of total bromide in foods,"HEEP COPYRIGHT: BIOL ABS. A simple method for the determination of total bromide in foods was investigated. A 10-g sample was ashed with MgO and dissolved in water. After centrifugation, the solution was oxidized with potassium dichromate sulfuric acid mixture in a Br generator. The liberated Br was reacted with fluorescein and quantitated by measurement of the absorbance at 515 nm. Cl ion did not interfere at up to 1200-fold excess. I ion was eliminated before the assay by bubbling N through the solution under mild oxidizing conditions. This method determined as little as 2.5 ppm Br in a sample. The recoveries of Br added to bread and fish jelly products were 98-104%.","Colorimetric determination of total bromide in foods Abs: HEEP COPYRIGHT: BIOL ABS. A simple method for the determination of total bromide in foods was investigated. A 10-g sample was ashed with MgO and dissolved in water. After centrifugation, the solution was oxidized with potassium dichromate sulfuric acid mixture in a Br generator. The liberated Br was reacted with fluorescein and quantitated by measurement of the absorbance at 515 nm. Cl ion did not interfere at up to 1200-fold excess. I ion was eliminated before the assay by bubbling N through the solution under mild oxidizing conditions. This method determined as little as 2.5 ppm Br in a sample. The recoveries of Br added to bread and fish jelly products were 98-104%."
1237831,Siegel et al. 1981,AMELIORATION OF TOXIC ACUTE RENAL FAILURE BY TREATMENT WITH THYROXINE,HEEP COPYRIGHT: BIOL ABS. ABSTRACT RAT HORMONE-DRUG ANTIDOTE POTASSIUM DI CHROMATE TOXICITY,AMELIORATION OF TOXIC ACUTE RENAL FAILURE BY TREATMENT WITH THYROXINE Abs: HEEP COPYRIGHT: BIOL ABS. ABSTRACT RAT HORMONE-DRUG ANTIDOTE POTASSIUM DI CHROMATE TOXICITY
1237830,Koenig and  H-G 1981,A RAPID AND EASY METHOD TO INTRODUCE DAPHNIA-MAGNA INTO TEST VESSELS,HEEP COPYRIGHT: BIOL ABS. NOTE POTASSIUM DI CHROMATE MORTALITY,A RAPID AND EASY METHOD TO INTRODUCE DAPHNIA-MAGNA INTO TEST VESSELS Abs: HEEP COPYRIGHT: BIOL ABS. NOTE POTASSIUM DI CHROMATE MORTALITY
1237826,Ramano MECHULAN et al. 1980,Contact dermatitis: Clinical and epidemiologic study of workers who handle potassium bichromate,"HEEP COPYRIGHT: BIOL ABS. A study of 700 workers was carried out in 2 footwear industries with 2 substances, K2Cr2O7 and p-phenylenediamine (1% aqueous solution). Workers with dermal sensitivity of any kind were chosen as samples of the working group; nonsensitive controls were selected from the same working group. The highest number of sensitive persons were those with erythematous reactions. The workers were more sensitive to bichromate. In one of the industries, females were more affected due to manual handling. The relation with atopy was not significant. Genetic factors, mass exposure and handling may influence the mechanism of sensitivity more than relative humidity.","Contact dermatitis: Clinical and epidemiologic study of workers who handle potassium bichromate Abs: HEEP COPYRIGHT: BIOL ABS. A study of 700 workers was carried out in 2 footwear industries with 2 substances, K2Cr2O7 and p-phenylenediamine (1% aqueous solution). Workers with dermal sensitivity of any kind were chosen as samples of the working group; nonsensitive controls were selected from the same working group. The highest number of sensitive persons were those with erythematous reactions. The workers were more sensitive to bichromate. In one of the industries, females were more affected due to manual handling. The relation with atopy was not significant. Genetic factors, mass exposure and handling may influence the mechanism of sensitivity more than relative humidity."
1237822,Turska et al. 1980,Electron microscopic studies on hepatocytes of hens intoxicated with potassium dichromate,"HEEP COPYRIGHT: BIOL ABS. After 3 days, acute poisoning symptoms were stated in some hepatocyte ultrastructures in livers of hens intoxicated with K2Cr2O7. They were manifested in damage of mitochondria, disappearance of ribosomes and fatty infiltration. No pathological changes were observed 20 days after intoxication.","Electron microscopic studies on hepatocytes of hens intoxicated with potassium dichromate Abs: HEEP COPYRIGHT: BIOL ABS. After 3 days, acute poisoning symptoms were stated in some hepatocyte ultrastructures in livers of hens intoxicated with K2Cr2O7. They were manifested in damage of mitochondria, disappearance of ribosomes and fatty infiltration. No pathological changes were observed 20 days after intoxication."
1237821,Kousa and  Soini 1980,Contact allergy to a stocking dye,"HEEP COPYRIGHT: BIOL ABS. Eczema patients (13 women and 1 man) had contact allergy to a brown stocking dye which is a mixture of nitrodiazobenzene, aminodiazobenzene and aminoanthraquinone dyes. Eleven of the patients reacted to p-phenylenediamine; 9 of 12 tested reacted to aminoazobenzene, 9 to Disperse Orange 3 and 4 to Disperse Yellow 3. Positive epicutaneous test reactions to the dye were found in 5 of 362 consecutive eczema patients tested (1.4%).","Contact allergy to a stocking dye Abs: HEEP COPYRIGHT: BIOL ABS. Eczema patients (13 women and 1 man) had contact allergy to a brown stocking dye which is a mixture of nitrodiazobenzene, aminodiazobenzene and aminoanthraquinone dyes. Eleven of the patients reacted to p-phenylenediamine; 9 of 12 tested reacted to aminoazobenzene, 9 to Disperse Orange 3 and 4 to Disperse Yellow 3. Positive epicutaneous test reactions to the dye were found in 5 of 362 consecutive eczema patients tested (1.4%)."
1237819,Miyai 1980,Absorption and accumulation of chromium in animals after chromium compound inhalation: 1. Accumulation in rats by long-term inhalation,"HEEP COPYRIGHT: BIOL ABS. Rats and mice were exposed to barium chromate (BC) (water insoluble) or sodium chromate (SC) (water soluble) dust in the lungs of BC-exposed rats and in the spleen, kidney, duodenum and testis of SC-exposed rats. Recommendations for new occupational standards are presented.","Absorption and accumulation of chromium in animals after chromium compound inhalation: 1. Accumulation in rats by long-term inhalation Abs: HEEP COPYRIGHT: BIOL ABS. Rats and mice were exposed to barium chromate (BC) (water insoluble) or sodium chromate (SC) (water soluble) dust in the lungs of BC-exposed rats and in the spleen, kidney, duodenum and testis of SC-exposed rats. Recommendations for new occupational standards are presented."
1237818,Wong and  Beaver 1980,Algal bioassays to determine toxicity of metal mixtures,"HEEP COPYRIGHT: BIOL ABS. The shortcomings of many established toxicity criteria for metals have resulted from a simplification of bioassays performed with single metals. A more comprehensive approach was needed to diagnose the effects of metal mixtures (The chemicals were: sodium arsenate, cadmium nitrate, potassium dichromate, copper sulfate, ferrous sulfate, lead nitrate, mercuric chloride, nickel sulfate, sodium selenite and zinc chloride) on aquatic organisms. Using Chlorella fusca Shihira et Krauss, Ankistrodesmus bibraianum Reinsch (= syn. with Selenastrum capricornutum Printz) and Scenedesmus quadricauda (TUrp.) Breb. as test organisms, a number of factors which affected metal toxicity bioassays were experimented on. These included metal interactions, algal competitions, species sensitivities, the ratio of an excess metal to other metals and nutrient levels. An alternative technique was finally established which involved an evaluation of individual assays of Chlorella and Ankistrodesmus in separate media and a tissue-metal analysis on Chlorella. C. fusca, commonly found in lakes with high metal concentrations, showed high tolerance to mixed-metal solutions, while Ankistrodesmus was very sensitive. By determining the maximum yield ratio between Ankistrodesmus and Chlorella (i.e., the A:Ch ratio), it was possible to compare the toxic strength of harmful metals according to an established standard curve of A:Ch ratio vs. mixed-metal concentrations. The levels of tissue-metal analyzed in Chlorella also gave some indication as to which metals were responsible for the toxicity.","Algal bioassays to determine toxicity of metal mixtures Abs: HEEP COPYRIGHT: BIOL ABS. The shortcomings of many established toxicity criteria for metals have resulted from a simplification of bioassays performed with single metals. A more comprehensive approach was needed to diagnose the effects of metal mixtures (The chemicals were: sodium arsenate, cadmium nitrate, potassium dichromate, copper sulfate, ferrous sulfate, lead nitrate, mercuric chloride, nickel sulfate, sodium selenite and zinc chloride) on aquatic organisms. Using Chlorella fusca Shihira et Krauss, Ankistrodesmus bibraianum Reinsch (= syn. with Selenastrum capricornutum Printz) and Scenedesmus quadricauda (TUrp.) Breb. as test organisms, a number of factors which affected metal toxicity bioassays were experimented on. These included metal interactions, algal competitions, species sensitivities, the ratio of an excess metal to other metals and nutrient levels. An alternative technique was finally established which involved an evaluation of individual assays of Chlorella and Ankistrodesmus in separate media and a tissue-metal analysis on Chlorella. C. fusca, commonly found in lakes with high metal concentrations, showed high tolerance to mixed-metal solutions, while Ankistrodesmus was very sensitive. By determining the maximum yield ratio between Ankistrodesmus and Chlorella (i.e., the A:Ch ratio), it was possible to compare the toxic strength of harmful metals according to an established standard curve of A:Ch ratio vs. mixed-metal concentrations. The levels of tissue-metal analyzed in Chlorella also gave some indication as to which metals were responsible for the toxicity."
1237817,Franke and  Hermann 1980,TOXICITY OF SUBSTANCES IN COMBINATION,HEEP COPYRIGHT: BIOL ABS. ABSTRACT MERCURIC CHLORIDE POTASSIUM CYANIDE NICKEL CHLORIDE POTASSIUM CHROMATE COPPER SULFATE PHENOL NITRO BENZENE,TOXICITY OF SUBSTANCES IN COMBINATION Abs: HEEP COPYRIGHT: BIOL ABS. ABSTRACT MERCURIC CHLORIDE POTASSIUM CYANIDE NICKEL CHLORIDE POTASSIUM CHROMATE COPPER SULFATE PHENOL NITRO BENZENE
1237815,Addo et al. 1980,THE RELATIONSHIP BETWEEN CONTACT ALLERGIC SENSITIVITY AND PERSISTENT LIGHT REACTION,HEEP COPYRIGHT: BIOL ABS. HUMAN XANTHIUM-STRUMARIUM COCKLEBUR PARTHENIUM-HYSTEROPHORUS WILD FEVERFEW ACHILLEA-MILLEFOLIUM YARROW SOLIDAGO-VIRGO-AUREA GOLDENROD CHRYSANTHEMUM-MORIFOLIUM ARTEMISIA-ABSINTHIUM SAGEBRUSH ANTHEMIS-COTULA DOG FENNEL TANACETUM-VULGARIS TANSY DAHLIA-SPP DAHLIA HELIANTHUS-SPP SUNFLOWER AMBROSIA-ARTEMISIIFOLIA SHORT RAGWEED COMPOSITAE OLEO RESINS COLOPHONY POTASSIUM DI CHROMATE RUBBER CHEMICALS PHOTO PATCH TEST PHOTO TOXICITY PHOTO SENSITIVITY PHOTO HEMOLYSIS TECHNIQUE UVA UV-B,THE RELATIONSHIP BETWEEN CONTACT ALLERGIC SENSITIVITY AND PERSISTENT LIGHT REACTION Abs: HEEP COPYRIGHT: BIOL ABS. HUMAN XANTHIUM-STRUMARIUM COCKLEBUR PARTHENIUM-HYSTEROPHORUS WILD FEVERFEW ACHILLEA-MILLEFOLIUM YARROW SOLIDAGO-VIRGO-AUREA GOLDENROD CHRYSANTHEMUM-MORIFOLIUM ARTEMISIA-ABSINTHIUM SAGEBRUSH ANTHEMIS-COTULA DOG FENNEL TANACETUM-VULGARIS TANSY DAHLIA-SPP DAHLIA HELIANTHUS-SPP SUNFLOWER AMBROSIA-ARTEMISIIFOLIA SHORT RAGWEED COMPOSITAE OLEO RESINS COLOPHONY POTASSIUM DI CHROMATE RUBBER CHEMICALS PHOTO PATCH TEST PHOTO TOXICITY PHOTO SENSITIVITY PHOTO HEMOLYSIS TECHNIQUE UVA UV-B
1237814,Masana et al. 1980,Preparation of mouse antiserum specific for rabbit beta2-microglobulin,HEEP COPYRIGHT: BIOL ABS. Antiserum specific for rabbit beta2-microglobulin was obtained from mouse. The antiserum was used for measuring concentration of this protein in rabbit urine by electrosyneresis. Its lower limit of the detection was 50 mg/l. Excretion of urinary beta2-microglobulin in the rabbit administered sodium chromate increased temporarily and reached to the maximum (above 800 mg/l) 2 days after the administration. Human implications are discussed.,Preparation of mouse antiserum specific for rabbit beta2-microglobulin Abs: HEEP COPYRIGHT: BIOL ABS. Antiserum specific for rabbit beta2-microglobulin was obtained from mouse. The antiserum was used for measuring concentration of this protein in rabbit urine by electrosyneresis. Its lower limit of the detection was 50 mg/l. Excretion of urinary beta2-microglobulin in the rabbit administered sodium chromate increased temporarily and reached to the maximum (above 800 mg/l) 2 days after the administration. Human implications are discussed.
1237809,Nomiyama et al. 1980,"Environmental temperature, a factor modifying the acute toxicity of organic solvents, heavy metals and agricultural chemicals","HEEP COPYRIGHT: BIOL ABS. Male mice (1500), previously acclimatized to 8?, 22? or 38? C, were used to determine the median lethal doses of organic solvents, heavy metals and agricultural chemicals by the Up-and-Down method via several routes of administration. Acute toxicity of benzene, trichloroethylene, mercuric chloride, cadium chloride, fratol, methylparathion and dieldrin increased markedly at a low temperature of 8? C, as well as at a high temperature of 38? C. Acute toxicity of toluene, copper sulfate and chromium trioxide was only enhanced at 38? C.","Environmental temperature, a factor modifying the acute toxicity of organic solvents, heavy metals and agricultural chemicals Abs: HEEP COPYRIGHT: BIOL ABS. Male mice (1500), previously acclimatized to 8?, 22? or 38? C, were used to determine the median lethal doses of organic solvents, heavy metals and agricultural chemicals by the Up-and-Down method via several routes of administration. Acute toxicity of benzene, trichloroethylene, mercuric chloride, cadium chloride, fratol, methylparathion and dieldrin increased markedly at a low temperature of 8? C, as well as at a high temperature of 38? C. Acute toxicity of toluene, copper sulfate and chromium trioxide was only enhanced at 38? C."
1237802,Tandon et al. 1980,Protection against mercuric chloride by nephrotoxic agents which do not induce thionein,"HEEP COPYRIGHT: BIOL ABS. Kidney damage caused by the i.p. administration of 1.1 mg/kg Hg given as HgCl2 was less marked in 7 wk old male rats when Hg was given 7 days after the administration of 1 of the following nephrotoxic agents: 20 mg/kg sodium chromate, 100 mg/kg p-aminophenol, or 500 mg/kg sodium maleate, or 14 days after the injection of 4.0 mg/kg uranyl acetate. All 4 nephrotoxic agents were given in sufficient doses to cause renal damage. In the first 3-4 days after the administration of the nephrotoxic agents, they increased the urinary excretion of alkaline phosphatase, glutamic oxaloacetic transaminase and lactic dehydrogenase and caused widespread necrosis in the proximal tubular cells. In the first 24 h after the injection of Hg, the urinary excretion of the 3 enzymes tested was lower in pretreated than in nonpretreated rats. Tubular cell necrosis was also less extensive in pretreated than in nonpretreated rats. Tubular cell necrosis was also less extensive in pretreated than in nonpretreated rats and calcification could be seen 10 days after Hg only in the kidneys of the nonpretreated rats. The decreased susceptibility of regenerating kidneys to the tubulotoxic effect of HgCl2 is a general phenomenon which is unrelated to the renal concentration of metalothionein or change in renal Hg uptake.","Protection against mercuric chloride by nephrotoxic agents which do not induce thionein Abs: HEEP COPYRIGHT: BIOL ABS. Kidney damage caused by the i.p. administration of 1.1 mg/kg Hg given as HgCl2 was less marked in 7 wk old male rats when Hg was given 7 days after the administration of 1 of the following nephrotoxic agents: 20 mg/kg sodium chromate, 100 mg/kg p-aminophenol, or 500 mg/kg sodium maleate, or 14 days after the injection of 4.0 mg/kg uranyl acetate. All 4 nephrotoxic agents were given in sufficient doses to cause renal damage. In the first 3-4 days after the administration of the nephrotoxic agents, they increased the urinary excretion of alkaline phosphatase, glutamic oxaloacetic transaminase and lactic dehydrogenase and caused widespread necrosis in the proximal tubular cells. In the first 24 h after the injection of Hg, the urinary excretion of the 3 enzymes tested was lower in pretreated than in nonpretreated rats. Tubular cell necrosis was also less extensive in pretreated than in nonpretreated rats. Tubular cell necrosis was also less extensive in pretreated than in nonpretreated rats and calcification could be seen 10 days after Hg only in the kidneys of the nonpretreated rats. The decreased susceptibility of regenerating kidneys to the tubulotoxic effect of HgCl2 is a general phenomenon which is unrelated to the renal concentration of metalothionein or change in renal Hg uptake."
1237793,Majone and  Rensi 1979,"Mitotic alterations, chromosome aberrations and sister chromatid exchanges induced by hexavalent and trivalent chromium on mammalian cells in vitro","The action of hexavalent chromium (potassium chromate) and trivalent chromium (chromium chloride) on the mitotic cycle and the induction of chromosome aberrations and of sister chromatid exchanges were analyzed in human and Chinese hamster cell lines in vitro. Both Cr6+ and Cr3+ induced mitotic alterations but specific mechanisms of actions, leading to blockages in different mitotic phases, characterized each of the 2 compounds. Chromosome aberrations are almost doubled after treatment with 0.15 mug/ml of Cr6+ and 50 mug/ml of Cr3+; chromatid gaps, breaks and interchanges are the most frequent aberrations induced. The frequency of sister chromatid exchanges is significantly increased after exposure to Cr6+, but not to Cr3+.","Mitotic alterations, chromosome aberrations and sister chromatid exchanges induced by hexavalent and trivalent chromium on mammalian cells in vitro Abs: The action of hexavalent chromium (potassium chromate) and trivalent chromium (chromium chloride) on the mitotic cycle and the induction of chromosome aberrations and of sister chromatid exchanges were analyzed in human and Chinese hamster cell lines in vitro. Both Cr6+ and Cr3+ induced mitotic alterations but specific mechanisms of actions, leading to blockages in different mitotic phases, characterized each of the 2 compounds. Chromosome aberrations are almost doubled after treatment with 0.15 mug/ml of Cr6+ and 50 mug/ml of Cr3+; chromatid gaps, breaks and interchanges are the most frequent aberrations induced. The frequency of sister chromatid exchanges is significantly increased after exposure to Cr6+, but not to Cr3+."
1237791,Luciani et al. 1979,Effects of chromium compounds on plasma membrane Mg2+-ATPase activity of BHK cells,"An ATPase activity stimulated by divalent ions (Mg2+, Ca2+, Mn2+, Zn2+) has been observed in intact hamster fibroblasts cultured in vitro (BHK line). Such activity has been determined by the incubation (30 min at 37°C) of washed cell suspensions (about 1 mg of proteins) in a medium containing 100 mM NaCl, 20 mM KCl, 15 mM Tris—HCl (pH 7.4), 10 mM NaHCO3, 5 mM glucose and equimolar concentrations of ATP and divalent cation. Mg2+-ATPase activity is insensitive to ouabain and lacks specificity towards nucleoside triphosphate substrates. AMP and ADP are not hydrolyzed under these conditions. Apparent Km of 0.76 mM and Vmax of 1.46 ?mol Pi · mg proteins?1 · h?1 have been calculated for Mg-ATP complex. This ATPase is an ectoenzyme, therefore its activity could be used as a suitable index of the action of chemicals like chromium compounds known for their cytotoxic effects on membrane functions. Salts of trivalent (CrCl3) and hexavalent (K2Cr2O7) chromium at concentrations ranging from 1 mM to 5 mM inhibit Mg2+-ATPase. The inhibition by K2Cr2O7 is observed after pretreatment of the cells with this compound followed by its absence from the assay medium “per se” for Mg2+-ATPase, and it is referred to the alterations of membrane bound enzyme structures by the oxidizing hexavalent chromium. The inhibition by CrCl3 is mainly evident when this compound is present in the incubation medium, and is referred to the interaction of trivalent chromium with Mg2+-ATP as it is partially reversed by increasing Mg2+-ATP concentration.","Effects of chromium compounds on plasma membrane Mg2+-ATPase activity of BHK cells Abs: An ATPase activity stimulated by divalent ions (Mg2+, Ca2+, Mn2+, Zn2+) has been observed in intact hamster fibroblasts cultured in vitro (BHK line). Such activity has been determined by the incubation (30 min at 37°C) of washed cell suspensions (about 1 mg of proteins) in a medium containing 100 mM NaCl, 20 mM KCl, 15 mM Tris—HCl (pH 7.4), 10 mM NaHCO3, 5 mM glucose and equimolar concentrations of ATP and divalent cation. Mg2+-ATPase activity is insensitive to ouabain and lacks specificity towards nucleoside triphosphate substrates. AMP and ADP are not hydrolyzed under these conditions. Apparent Km of 0.76 mM and Vmax of 1.46 ?mol Pi · mg proteins?1 · h?1 have been calculated for Mg-ATP complex. This ATPase is an ectoenzyme, therefore its activity could be used as a suitable index of the action of chemicals like chromium compounds known for their cytotoxic effects on membrane functions. Salts of trivalent (CrCl3) and hexavalent (K2Cr2O7) chromium at concentrations ranging from 1 mM to 5 mM inhibit Mg2+-ATPase. The inhibition by K2Cr2O7 is observed after pretreatment of the cells with this compound followed by its absence from the assay medium “per se” for Mg2+-ATPase, and it is referred to the alterations of membrane bound enzyme structures by the oxidizing hexavalent chromium. The inhibition by CrCl3 is mainly evident when this compound is present in the incubation medium, and is referred to the interaction of trivalent chromium with Mg2+-ATP as it is partially reversed by increasing Mg2+-ATP concentration."
1237787,Rubenstein and  Soares J 1979,The effect of selenium on the biliary excretion and tissue deposition of 2 forms of mercury in the broiler chick,"HEEP COPYRIGHT: BIOL ABS. Four wk old male broiler chicks were used to study the mechanism of the interaction between Hg and Se. Chicks were fed diets supplemented with methylmercuric chloride (CH3HgCl) at 6.5 or 13 ppm or mercuric chloride (HgCl2) at 96.0 or 192.0 ppm and 0.05, or 4.0 ppm Se as Na2SeO3 for 2-12 days. These Hg levels approximated 5.0 and 10.0 ppm available Hg, assuming 95% absorption for CH3Hg+ and 7% for Hg2+. Bile, liver kidney, excreta and intestinal wall segments were analyzed for total Hg by flameless atomic absorption spectrophotometry. A dietary marker, chromic oxide, was incorporated into the diets to determine total Hg excretion. Addition of Hg to the diet increased its accumulation in all tissues and this increase reflected the length of time on the treatment. CH3HgCl feeding resulted in Hg deposited primarily in the liver while maximal Hg accumulation from dietary HgCl2 occurred in the kidney. Based on intestinal wall Hg concentration, the upper small intestine appears to be the site of preferential absorption of CH3Hg+, whereas Hg2+ appears to be maximally absorbed in the ileum and lower intestine. An equimolar addition of Se and Hg to the diet generally increased Hg concentrations in the ileum. Bile servides as an important mode of Hg excretion in avians for both types of Hg. Addition of Se increased total Hg excretion for dietary CH3Hg+. In these short-term studies, there were no major effects from Hg with or without added Se as measured by body wt gain and gross symptoms of toxicity. Hg has been used extensively in seed dressings.","The effect of selenium on the biliary excretion and tissue deposition of 2 forms of mercury in the broiler chick Abs: HEEP COPYRIGHT: BIOL ABS. Four wk old male broiler chicks were used to study the mechanism of the interaction between Hg and Se. Chicks were fed diets supplemented with methylmercuric chloride (CH3HgCl) at 6.5 or 13 ppm or mercuric chloride (HgCl2) at 96.0 or 192.0 ppm and 0.05, or 4.0 ppm Se as Na2SeO3 for 2-12 days. These Hg levels approximated 5.0 and 10.0 ppm available Hg, assuming 95% absorption for CH3Hg+ and 7% for Hg2+. Bile, liver kidney, excreta and intestinal wall segments were analyzed for total Hg by flameless atomic absorption spectrophotometry. A dietary marker, chromic oxide, was incorporated into the diets to determine total Hg excretion. Addition of Hg to the diet increased its accumulation in all tissues and this increase reflected the length of time on the treatment. CH3HgCl feeding resulted in Hg deposited primarily in the liver while maximal Hg accumulation from dietary HgCl2 occurred in the kidney. Based on intestinal wall Hg concentration, the upper small intestine appears to be the site of preferential absorption of CH3Hg+, whereas Hg2+ appears to be maximally absorbed in the ileum and lower intestine. An equimolar addition of Se and Hg to the diet generally increased Hg concentrations in the ileum. Bile servides as an important mode of Hg excretion in avians for both types of Hg. Addition of Se increased total Hg excretion for dietary CH3Hg+. In these short-term studies, there were no major effects from Hg with or without added Se as measured by body wt gain and gross symptoms of toxicity. Hg has been used extensively in seed dressings."
1237783,Gilani and  Marano 1979,Chromium poisoning and chick embryogenesis,"HEEP COPYRIGHT: BIOL ABS. The effects of Cr on chick embryos were analyzed in the present study. Chromium trioxide was dissolved in saline and injected into embryonating chicken eggs at doses ranging from 0.002-0.05 mg/egg. The injections were made into the air sacs of eggs at Days 0, 1, 2, 3, and 4 of incubation. Control eggs were injected with an equivalent volume of saline (0.1 ml/egg). In all, 840 chicken eggs were used for this study. All the embryos were examined at Day 8. The following malformations were observed: short and twisted limbs, microphthalmia, exencephaly, short and twisted neck, everted viscera, edema and reduced body size. Most of the embryos showed unilateral and bilateral limb defects. Chromium trioxide had the tendency to cause malformations in the chick embryos tested.","Chromium poisoning and chick embryogenesis Abs: HEEP COPYRIGHT: BIOL ABS. The effects of Cr on chick embryos were analyzed in the present study. Chromium trioxide was dissolved in saline and injected into embryonating chicken eggs at doses ranging from 0.002-0.05 mg/egg. The injections were made into the air sacs of eggs at Days 0, 1, 2, 3, and 4 of incubation. Control eggs were injected with an equivalent volume of saline (0.1 ml/egg). In all, 840 chicken eggs were used for this study. All the embryos were examined at Day 8. The following malformations were observed: short and twisted limbs, microphthalmia, exencephaly, short and twisted neck, everted viscera, edema and reduced body size. Most of the embryos showed unilateral and bilateral limb defects. Chromium trioxide had the tendency to cause malformations in the chick embryos tested."
1237782,Segal et al. 1979,Ritual-enema-induced colitis,"HEEP COPYRIGHT: BIOL ABS. Enemas are routinely used in South Africa for various reasons including for ritual purposes; as an aperient, aphrodisiac or emetic; and for the treatment of impotence, febrile symptoms, abdominal pains, dysmenorrhea and dysentery. Substances used include herbal medicines, Dettol, vinegar, caustics, soap, potassium dichromate, copper sulfate, potassium permanganate and brown sugar. Eleven patients in whom colitis developed following enema administration are described. Peritonitis and rectal bleeding are the clinical hallmarks. Features demonstrated by roentgenogram vary from ostensibly normal to fistula and stricture formation. In mild cases, there are occasionally neutrophils in the lamina propria; in severe cases, complete necrosis of the bowel wall is observed. Conservative therapy is advocated for the mild cases. The type of operative treatment performed depends on the complication observed.","Ritual-enema-induced colitis Abs: HEEP COPYRIGHT: BIOL ABS. Enemas are routinely used in South Africa for various reasons including for ritual purposes; as an aperient, aphrodisiac or emetic; and for the treatment of impotence, febrile symptoms, abdominal pains, dysmenorrhea and dysentery. Substances used include herbal medicines, Dettol, vinegar, caustics, soap, potassium dichromate, copper sulfate, potassium permanganate and brown sugar. Eleven patients in whom colitis developed following enema administration are described. Peritonitis and rectal bleeding are the clinical hallmarks. Features demonstrated by roentgenogram vary from ostensibly normal to fistula and stricture formation. In mild cases, there are occasionally neutrophils in the lamina propria; in severe cases, complete necrosis of the bowel wall is observed. Conservative therapy is advocated for the mild cases. The type of operative treatment performed depends on the complication observed."
1237781,Himebaugh and  Smith 1979,Semi-micro tube method for chemical oxygen demand,"HEEP COPYRIGHT: BIOL ABS. Through chemical and biological oxidation, organic material released to receiving waters can greatly reduce or deplete dissolved oxygen. There have been several methods developed to measure this oxygen demand and 2, the Biochemical Oxygen Demand (BOD) test and the Chemical Oxygen Demand (COD) test, have emerged as the most popular. While the BOD determination closely approximates the actual oxygen demand present under sample conditions, the COD determination measures the portion of organic matter present that can be oxidized by a strong chemical oxidant. Although both tests are parameters used for indicating the general presence of organic pollution, the COD measurement has several advantages that have increased its popularity in recent years. Basically, the method involves a 2 h sample oxidation by a known excess of potassium dichromate in hot 50% sulfuric acid. This method was further optimized by the addition of several modifications. Like the AutoAnalyzer method, this method reduces analytical time, glassware cleaning, and reagent cost, yet requires less space and equipment than either the standard method or the AutoAnalyzer method.","Semi-micro tube method for chemical oxygen demand Abs: HEEP COPYRIGHT: BIOL ABS. Through chemical and biological oxidation, organic material released to receiving waters can greatly reduce or deplete dissolved oxygen. There have been several methods developed to measure this oxygen demand and 2, the Biochemical Oxygen Demand (BOD) test and the Chemical Oxygen Demand (COD) test, have emerged as the most popular. While the BOD determination closely approximates the actual oxygen demand present under sample conditions, the COD determination measures the portion of organic matter present that can be oxidized by a strong chemical oxidant. Although both tests are parameters used for indicating the general presence of organic pollution, the COD measurement has several advantages that have increased its popularity in recent years. Basically, the method involves a 2 h sample oxidation by a known excess of potassium dichromate in hot 50% sulfuric acid. This method was further optimized by the addition of several modifications. Like the AutoAnalyzer method, this method reduces analytical time, glassware cleaning, and reagent cost, yet requires less space and equipment than either the standard method or the AutoAnalyzer method."
1237780,Fales 1979,"The influence of temperature and salinity on the accumulation and elimination of chromium by the grass shrimp, Palaemonetes pugio (Holthuis)","HEEP COPYRIGHT: BIOL ABS. Grass shrimp exposed to sodium chromate in 8 different thermosaline combinations accumulated Cr more quickly at the higher temperatures and lower salinity, but the response to changes in 1 variable was not the same at all levels of the 2nd variable. This interaction implies that changes in the rate of Cr accumulation with changes in salinity cannot be predicted for all temperatures based upon data collected at only 1 temperature. Although temperature and salinity influence the accumulation of Cr, only temperature has a detectable effect upon subsequent elimination. The rate of elimination was lowest at 10 C and highest at 20? and 25? C.","The influence of temperature and salinity on the accumulation and elimination of chromium by the grass shrimp, Palaemonetes pugio (Holthuis) Abs: HEEP COPYRIGHT: BIOL ABS. Grass shrimp exposed to sodium chromate in 8 different thermosaline combinations accumulated Cr more quickly at the higher temperatures and lower salinity, but the response to changes in 1 variable was not the same at all levels of the 2nd variable. This interaction implies that changes in the rate of Cr accumulation with changes in salinity cannot be predicted for all temperatures based upon data collected at only 1 temperature. Although temperature and salinity influence the accumulation of Cr, only temperature has a detectable effect upon subsequent elimination. The rate of elimination was lowest at 10 C and highest at 20? and 25? C."
1237774,Pasricha and  Kanwar 1978,SUBSTANCES CAUSING CONTACT DERMATITIS,HEEP COPYRIGHT: BIOL ABS. HUMAN PROFESSIONAL PURSUITS HOBBIES COSMETICS CLOTHING MEDICINE AIRBORNE ANTIGENS,SUBSTANCES CAUSING CONTACT DERMATITIS Abs: HEEP COPYRIGHT: BIOL ABS. HUMAN PROFESSIONAL PURSUITS HOBBIES COSMETICS CLOTHING MEDICINE AIRBORNE ANTIGENS
1237772,Nestmann 1978,GENETIC ACTIVITY OF LEAD CHROMATE IN BACTERIA AND OF ACTINOMYCIN D IN YEAST,HEEP COPYRIGHT: BIOL ABS. ABSTRACT MAMMAL CARCINOGEN ESCHERICHIA-COLI SACCHAROMYCES-CEREVISIAE,GENETIC ACTIVITY OF LEAD CHROMATE IN BACTERIA AND OF ACTINOMYCIN D IN YEAST Abs: HEEP COPYRIGHT: BIOL ABS. ABSTRACT MAMMAL CARCINOGEN ESCHERICHIA-COLI SACCHAROMYCES-CEREVISIAE
1237770,Mukherji and  Roy 1978,Characterization of chromium toxicity in different plant materials,"HEEP COPYRIGHT: BIOL ABS. Effects of deleterious concentrations of chromium (K2Cr3O7) on the germination and seedling growth of the mung bean (Phaseolus aureus) was studied. Germination was increasingly inhibited at concentrations above 5nd inhibition of seedling growth began at the lowest concentration. Inhibition of seedling growth could partially be reversed by GA3, KCl, FeCl3, MnCl2 and citric acid; other compounds were ineffective. When applied alone or in combination with IAA, chromium completely inhibited cell enlargement in wheat coleoptile sections. Buffer soluble protein, turbidity of the homogenates and heat coagulability of cytoplasmic proteins increased. Plasmolysis in tissue slices pretreated with Cr was permanent and irreversible. Coincident with growth inhibition, there was a difference in the pattern of distribution of sugar and N in the embryo and the cotyledons.","Characterization of chromium toxicity in different plant materials Abs: HEEP COPYRIGHT: BIOL ABS. Effects of deleterious concentrations of chromium (K2Cr3O7) on the germination and seedling growth of the mung bean (Phaseolus aureus) was studied. Germination was increasingly inhibited at concentrations above 5nd inhibition of seedling growth began at the lowest concentration. Inhibition of seedling growth could partially be reversed by GA3, KCl, FeCl3, MnCl2 and citric acid; other compounds were ineffective. When applied alone or in combination with IAA, chromium completely inhibited cell enlargement in wheat coleoptile sections. Buffer soluble protein, turbidity of the homogenates and heat coagulability of cytoplasmic proteins increased. Plasmolysis in tissue slices pretreated with Cr was permanent and irreversible. Coincident with growth inhibition, there was a difference in the pattern of distribution of sugar and N in the embryo and the cotyledons."
1237765,Reubi 1978,PATHOGENESIS AND RENAL FUNCTION IN ACUTE TOXIC NEPHROPATHIES,HEEP COPYRIGHT: BIOL ABS. HUMAN ANIMAL CELLULAR POISONS URANYL NITRATE MERCURIC SALTS POTASSIUM BI CHROMATE CARBON TETRA CHLORIDE POTASSIUM CHLORATE ORGANIC SOLVENTS OXALIC-ACID MALEIC-ACID ETHYLENE GLYCOL FOLIC-ACID CARBON MON OXIDE CALCIUM VERSENATE MUSHROOMS TETRACYCLINES SULFONAMIDES GENTAMICIN AMPHOTERICIN B,PATHOGENESIS AND RENAL FUNCTION IN ACUTE TOXIC NEPHROPATHIES Abs: HEEP COPYRIGHT: BIOL ABS. HUMAN ANIMAL CELLULAR POISONS URANYL NITRATE MERCURIC SALTS POTASSIUM BI CHROMATE CARBON TETRA CHLORIDE POTASSIUM CHLORATE ORGANIC SOLVENTS OXALIC-ACID MALEIC-ACID ETHYLENE GLYCOL FOLIC-ACID CARBON MON OXIDE CALCIUM VERSENATE MUSHROOMS TETRACYCLINES SULFONAMIDES GENTAMICIN AMPHOTERICIN B
1237761,Harrison et al. 1978,"The synthesis and chemistry of (11-14C)-dibenz (b,f)(1,4)oxazepine","HEEP COPYRIGHT: BIOL ABS. The synthesis of (11-14C)-dibenz(b,f)(1,4)oxazepine (1; a sensory irritant) is described. Chromium trioxide-pyridine oxidation of 1 gives (11-14C)-10,11-dihydrodibenz(b,f)(1,4)oxazepin-11-one, which on hydrolysis gives 2-amino-2'-(14C)-carboxydiphenylether. Hydrogenation of 1 affords (11-14C)-10,11-dihydrodibenz(b,f)(1,4)oxazepine. The enzymic conversion of 1 into 2-amino-2'-(14C)-hydroxymethyldiphenyl ether is described.","The synthesis and chemistry of (11-14C)-dibenz (b,f)(1,4)oxazepine Abs: HEEP COPYRIGHT: BIOL ABS. The synthesis of (11-14C)-dibenz(b,f)(1,4)oxazepine (1; a sensory irritant) is described. Chromium trioxide-pyridine oxidation of 1 gives (11-14C)-10,11-dihydrodibenz(b,f)(1,4)oxazepin-11-one, which on hydrolysis gives 2-amino-2'-(14C)-carboxydiphenylether. Hydrogenation of 1 affords (11-14C)-10,11-dihydrodibenz(b,f)(1,4)oxazepine. The enzymic conversion of 1 into 2-amino-2'-(14C)-hydroxymethyldiphenyl ether is described."
1237757,Levis et al. 1978,Cytotoxic effects of hexavalent and trivalent chromium on mammalian cells in vitro,"HEEP COPYRIGHT: BIOL ABS. The cytotoxic effects of carcinogenic hexavalent (K2Cr2O7) and trivalent (CrCl3) compounds were studied in cultured hamster fibroblasts (BHK kidney line) and human epithelial-like cells (HEp epidermoid laryngeal carcinoma line). K2Cr2O7 stimulates the uptake of labeled thymidine (TdR) into the soluble intracellular pool (the stimulation of nucleoside uptake represents a specific effect of Cr6+) while Cr3+ always exerts an inhibitory action. DNA synthesis is inhibited by treatment with both Cr compounds, but especially by K2Cr2O7. The effective CrCl3 concentrations reduce the sensitivity of DNA and RNA to hydrolysis with perchloric acid. Treatment with K2Cr2O7 in balanced salt solution, where Cr6+ reduction is less marked, induce more pronounced cytotoxic effects than treatment in complete growth medium. HEp cells were more sensitive to K2Cr2O7 than BHK fibroblasts. In the former line TdR uptake is less stimulated; DNA synthesis and cell survival are more affected. Survival of BHK cells to K2Cr2O7 indicates a multihit mechanism of cell inactivation, the extrapolation number being about 10. On the basis of quantitative Cr determinations in the treatment solutions and treated cells, the cytotoxic effects of Cr are attributed to the action of Cr6+ at the plasma membrane level on the mechanisms involved in nucleoside uptake, and interaction of Cr3+ at the intracellular level with nucleophilic targets on the DNA molecule.","Cytotoxic effects of hexavalent and trivalent chromium on mammalian cells in vitro Abs: HEEP COPYRIGHT: BIOL ABS. The cytotoxic effects of carcinogenic hexavalent (K2Cr2O7) and trivalent (CrCl3) compounds were studied in cultured hamster fibroblasts (BHK kidney line) and human epithelial-like cells (HEp epidermoid laryngeal carcinoma line). K2Cr2O7 stimulates the uptake of labeled thymidine (TdR) into the soluble intracellular pool (the stimulation of nucleoside uptake represents a specific effect of Cr6+) while Cr3+ always exerts an inhibitory action. DNA synthesis is inhibited by treatment with both Cr compounds, but especially by K2Cr2O7. The effective CrCl3 concentrations reduce the sensitivity of DNA and RNA to hydrolysis with perchloric acid. Treatment with K2Cr2O7 in balanced salt solution, where Cr6+ reduction is less marked, induce more pronounced cytotoxic effects than treatment in complete growth medium. HEp cells were more sensitive to K2Cr2O7 than BHK fibroblasts. In the former line TdR uptake is less stimulated; DNA synthesis and cell survival are more affected. Survival of BHK cells to K2Cr2O7 indicates a multihit mechanism of cell inactivation, the extrapolation number being about 10. On the basis of quantitative Cr determinations in the treatment solutions and treated cells, the cytotoxic effects of Cr are attributed to the action of Cr6+ at the plasma membrane level on the mechanisms involved in nucleoside uptake, and interaction of Cr3+ at the intracellular level with nucleophilic targets on the DNA molecule."
1237751,Majone 1977,Effects of potassium dichromate on mitosis of cultured mammalian cells,"HEEP COPYRIGHT: BIOL ABS. The effects of a soluble Cr6+ compound (potassium dichromate) on a human cell line (Hep-2 laryngeal carcinoma) were examined, taking into account: the changes of mitotic index, the changes of the frequency of the different mitotic phases and the induction rates of the main karyological and cytological alterations. Dichromate induces: a blockage of the cells which are in mitosis at the time of treatment, which takes place at metaphase and anaphase; an early mitotic inhibition on the cells which are in the G2 phase of the cell cycle; a recovery of cell division, after the mitotic inhibition, apparently accompanied by a partial cell synchronization; a late mitotic blockage when cell division recovers, which occurs mainly at metaphase (Such blockage is related to several karyological and cytological alterations: sticky or lagging unoriented chromosomes in the metaphase plate, chromosome bridges at anaphase and telophase and cytoplasmic bridges at interphase.); a large proportion of multinucleated (mostly binucleated) cells, whose rate follows telophase onset. On account of the high frequency of chromosome and cytoplasmic bridge, it is suggested that binucleated cells derive from fusion of sister, postmitotic cells. Cr6+ thus induces marked cytotoxic and cytogenic effects, related to a differential action on the different phases of the cell cycle.","Effects of potassium dichromate on mitosis of cultured mammalian cells Abs: HEEP COPYRIGHT: BIOL ABS. The effects of a soluble Cr6+ compound (potassium dichromate) on a human cell line (Hep-2 laryngeal carcinoma) were examined, taking into account: the changes of mitotic index, the changes of the frequency of the different mitotic phases and the induction rates of the main karyological and cytological alterations. Dichromate induces: a blockage of the cells which are in mitosis at the time of treatment, which takes place at metaphase and anaphase; an early mitotic inhibition on the cells which are in the G2 phase of the cell cycle; a recovery of cell division, after the mitotic inhibition, apparently accompanied by a partial cell synchronization; a late mitotic blockage when cell division recovers, which occurs mainly at metaphase (Such blockage is related to several karyological and cytological alterations: sticky or lagging unoriented chromosomes in the metaphase plate, chromosome bridges at anaphase and telophase and cytoplasmic bridges at interphase.); a large proportion of multinucleated (mostly binucleated) cells, whose rate follows telophase onset. On account of the high frequency of chromosome and cytoplasmic bridge, it is suggested that binucleated cells derive from fusion of sister, postmitotic cells. Cr6+ thus induces marked cytotoxic and cytogenic effects, related to a differential action on the different phases of the cell cycle."
1237750,Larcan et al. 1977,POTASSIUM BI CHROMATE INTOXICATION,HEEP COPYRIGHT: BIOL ABS. ABSTRACT HUMAN ESO PHARYNGEAL MUCOSA GASTRO ENTERITIS EXTRACELLULAR DEHYDRATION INTRA VASCULAR HEMOLYSIS HEPATO NEPHRITIS,POTASSIUM BI CHROMATE INTOXICATION Abs: HEEP COPYRIGHT: BIOL ABS. ABSTRACT HUMAN ESO PHARYNGEAL MUCOSA GASTRO ENTERITIS EXTRACELLULAR DEHYDRATION INTRA VASCULAR HEMOLYSIS HEPATO NEPHRITIS
1237747,Wennersten 1977,Photodynamic aspects of some metal complexes,"HEEP COPYRIGHT: BIOL ABS. The potential phototoxic capacity of some metal compounds of clinical significance in dermatology was investigated by means of the photohemolysis technique. No photosensitized hemolysis of (human) erythrocytes was observed with the Cr, Ni, Cu and Co compounds studied. Ni and Co compounds were efficient in quenching singlet O2 mediated photo-oxidative membrane damage of red blood cells. Cd compounds showed a pronounced photohemolytic activity and the reaction was O2 dependent. The 2H test for singlet O2 showed a significant increase in photohemolytic efficiency. The addition of histidine, a known quencher of singlet O2, resulted in a significant inhibition of the photohemolysis. Pronounced photo-oxidative damage to plasma membranes was also observed in in vitro cultivated cells by means of scanning electron microscopy. (Allergic contact dermatitis is discussed.)","Photodynamic aspects of some metal complexes Abs: HEEP COPYRIGHT: BIOL ABS. The potential phototoxic capacity of some metal compounds of clinical significance in dermatology was investigated by means of the photohemolysis technique. No photosensitized hemolysis of (human) erythrocytes was observed with the Cr, Ni, Cu and Co compounds studied. Ni and Co compounds were efficient in quenching singlet O2 mediated photo-oxidative membrane damage of red blood cells. Cd compounds showed a pronounced photohemolytic activity and the reaction was O2 dependent. The 2H test for singlet O2 showed a significant increase in photohemolytic efficiency. The addition of histidine, a known quencher of singlet O2, resulted in a significant inhibition of the photohemolysis. Pronounced photo-oxidative damage to plasma membranes was also observed in in vitro cultivated cells by means of scanning electron microscopy. (Allergic contact dermatitis is discussed.)"
1237746,Marchenko and  Broitman 1977,Occupational hygiene of an inductive surfacing process of agricultural machinery components with hard high chromium alloys,"HEEP COPYRIGHT: BIOL ABS. Dust was studied during metal surfacing processes of agricultural machinery parts with a high Cr alloy containing 50% chromium oxide, 36% iron carbide, 2-3% silicon dioxide, 2% Mg and traces of Ni, Cu and B. Dust was present in an aerosol form during several operational processes. Chronic Cr intoxication occurred in long-term workers. An objective investigation revealed 2 cases of pharyngitis of occupation origin and mild anemia. Measures were proposed for different stages of the metal surfacing process to alleviate health hazards. Protection against IR radiation used in the process was also stressed.","Occupational hygiene of an inductive surfacing process of agricultural machinery components with hard high chromium alloys Abs: HEEP COPYRIGHT: BIOL ABS. Dust was studied during metal surfacing processes of agricultural machinery parts with a high Cr alloy containing 50% chromium oxide, 36% iron carbide, 2-3% silicon dioxide, 2% Mg and traces of Ni, Cu and B. Dust was present in an aerosol form during several operational processes. Chronic Cr intoxication occurred in long-term workers. An objective investigation revealed 2 cases of pharyngitis of occupation origin and mild anemia. Measures were proposed for different stages of the metal surfacing process to alleviate health hazards. Protection against IR radiation used in the process was also stressed."
1237745,Bigaliev et al. 1977,Evaluation of the mutagenic activity of chromium compounds,"HEEP COPYRIGHT: BIOL ABS. The mutagenic activity of chromium compounds was studied on an embryonic fibroblast cell culture and human peripheral blood lymphocytes. With the embryonal fibroblasts culture, a significant (P 0.01) increase of the mutagenous effect produced by potassium bichromate as against control (5.4 | 0.91% of cells with the chromosomes aberrations) was shown. A cytogenetic examination of workers engaged in the production of chromium demonstrated the presence of a significant (P 0.01; 0.05) mutagenous activity of 5 chromium compounds entering the body in the form of aerosols. The most pronounced mutagenic action occurred with hexavalent chromium compounds.","Evaluation of the mutagenic activity of chromium compounds Abs: HEEP COPYRIGHT: BIOL ABS. The mutagenic activity of chromium compounds was studied on an embryonic fibroblast cell culture and human peripheral blood lymphocytes. With the embryonal fibroblasts culture, a significant (P 0.01) increase of the mutagenous effect produced by potassium bichromate as against control (5.4 | 0.91% of cells with the chromosomes aberrations) was shown. A cytogenetic examination of workers engaged in the production of chromium demonstrated the presence of a significant (P 0.01; 0.05) mutagenous activity of 5 chromium compounds entering the body in the form of aerosols. The most pronounced mutagenic action occurred with hexavalent chromium compounds."
1237744,Easty and  Wabers 1977,Determination of polychlorinated biphenyls in paper mill effluents and process streams,"HEEP COPYRIGHT: BIOL ABS. Special techniques were necessary for isolating PCB (polychlorinated biphenyls) from cellulose fiber-containing effluents and process streams and for determining PCB in effluents from paper mills using recycled fiber. Sources of potential PCB loss from aqueous solutions are revealed and means of avoiding these losses are proposed. Significant amounts of PCB remained on cellulose fibers following separatory funnel extraction of a fiber-water suspension with hexane or methylene chloride-hexane. Reflux of the fibers with alcoholic KOH was necessary to remove the remaining PCB. PCB losses due to volatilization from aqueous solution occurred during analysis, but these were minimized by working in a cool environment and covering the sample with a layer of hexane. The presence of cellulose fibers in PCB-containing effluents enhanced the effluents' stability during storage. Chromium trioxide oxidation was valuable in cleaning up extracts from paper mill effluents. Perchlorination is apt to yield misleading results.","Determination of polychlorinated biphenyls in paper mill effluents and process streams Abs: HEEP COPYRIGHT: BIOL ABS. Special techniques were necessary for isolating PCB (polychlorinated biphenyls) from cellulose fiber-containing effluents and process streams and for determining PCB in effluents from paper mills using recycled fiber. Sources of potential PCB loss from aqueous solutions are revealed and means of avoiding these losses are proposed. Significant amounts of PCB remained on cellulose fibers following separatory funnel extraction of a fiber-water suspension with hexane or methylene chloride-hexane. Reflux of the fibers with alcoholic KOH was necessary to remove the remaining PCB. PCB losses due to volatilization from aqueous solution occurred during analysis, but these were minimized by working in a cool environment and covering the sample with a layer of hexane. The presence of cellulose fibers in PCB-containing effluents enhanced the effluents' stability during storage. Chromium trioxide oxidation was valuable in cleaning up extracts from paper mill effluents. Perchlorination is apt to yield misleading results."
1237743,Wallace et al. 1977,Synthesis of radiolabeled T-2 toxin,"HEEP COPYRIGHT: BIOL ABS. 3H-labeled T-2 toxin (4beta,15-diacetoxy,8alpha-(3-methylbutyryloxy)-3alpha-hydroxy-12,13-epoxytrichothec-9-ene) was synthesized using a 2-step process. First, the C-3 hydroxyl was oxidized to a ketone using either chromium trioxide-pyridine or dimethyl sulfide-N-chlorosuccinimide complex. In step 2, the ketone was reduced with either (3H)-sodium cyanoborohydride or (3H)-sodium borohydride to a mixture of epimers which were separable by TLC. The alpha epimer (naturally occurring T-2 toxin) was formed predominantly, i.e., alpha:beta ratio was 4-1. Final reduction with (3H) sodium borohydride yielded (3-3H)T-2 toxin in 23% yield with a specific activity of 790 mCi/mmol. The labeled product, when equilibrated with 0.01 N HC1, did not lose the 3H indicating that no labile 3H was incorporated into T-2 toxin. The oxidation of (3-3H)T-2 toxin resulted in total loss of activity in the corresponding ketone. The metabolites of species of Fusarium are commonly found in foodstuff and are prominent because of their association with cases of mycotoxicoses.","Synthesis of radiolabeled T-2 toxin Abs: HEEP COPYRIGHT: BIOL ABS. 3H-labeled T-2 toxin (4beta,15-diacetoxy,8alpha-(3-methylbutyryloxy)-3alpha-hydroxy-12,13-epoxytrichothec-9-ene) was synthesized using a 2-step process. First, the C-3 hydroxyl was oxidized to a ketone using either chromium trioxide-pyridine or dimethyl sulfide-N-chlorosuccinimide complex. In step 2, the ketone was reduced with either (3H)-sodium cyanoborohydride or (3H)-sodium borohydride to a mixture of epimers which were separable by TLC. The alpha epimer (naturally occurring T-2 toxin) was formed predominantly, i.e., alpha:beta ratio was 4-1. Final reduction with (3H) sodium borohydride yielded (3-3H)T-2 toxin in 23% yield with a specific activity of 790 mCi/mmol. The labeled product, when equilibrated with 0.01 N HC1, did not lose the 3H indicating that no labile 3H was incorporated into T-2 toxin. The oxidation of (3-3H)T-2 toxin resulted in total loss of activity in the corresponding ketone. The metabolites of species of Fusarium are commonly found in foodstuff and are prominent because of their association with cases of mycotoxicoses."
1237741,Collins and  Tenney 1977,Fishery waste effluents: A suggested system for determining and calculating pollutant parameters,"HEEP COPYRIGHT: BIOL ABS. An improved and simplified system to test for pollutants in shrimp waste effluents is presented. In addition, 2 methods were developed to calculate protein and oil and grease content. The 1st method is based on establishing empirical regressions of protein or oil and grease on total residue. The 2nd and preferred method, a simultaneous equation, is independent of these correlations but dependent on the total residue and chemical oxygen demand (COD) of the waste effluent obtained through routine analyses. The COD value depended on the amount of potassium dichromate remaining at the completion of the 2-h reflux period. The dichromate can vary from 0-6.25 meq excess, and between 2 and 5 meq, the COD will vary 4.2%. A table of factors is given to correct the COD to 3.5 meq excess. Coefficients of COD were determined on a number of preparations of protein and oil and grease from shrimp waste effluent and from fish and shellfish. These coefficients (1.338 mg COD/mg protein and 2.678 mg COD/mg oil and grease) were required for the simultaneous equation. The simple analytical tests and mathematical treatment used in this system would be less expensive to the industry and would result in a more accurate and comprehensive evaluation of the waste load than currently obtainable by methods specified in the monitoring regulations.","Fishery waste effluents: A suggested system for determining and calculating pollutant parameters Abs: HEEP COPYRIGHT: BIOL ABS. An improved and simplified system to test for pollutants in shrimp waste effluents is presented. In addition, 2 methods were developed to calculate protein and oil and grease content. The 1st method is based on establishing empirical regressions of protein or oil and grease on total residue. The 2nd and preferred method, a simultaneous equation, is independent of these correlations but dependent on the total residue and chemical oxygen demand (COD) of the waste effluent obtained through routine analyses. The COD value depended on the amount of potassium dichromate remaining at the completion of the 2-h reflux period. The dichromate can vary from 0-6.25 meq excess, and between 2 and 5 meq, the COD will vary 4.2%. A table of factors is given to correct the COD to 3.5 meq excess. Coefficients of COD were determined on a number of preparations of protein and oil and grease from shrimp waste effluent and from fish and shellfish. These coefficients (1.338 mg COD/mg protein and 2.678 mg COD/mg oil and grease) were required for the simultaneous equation. The simple analytical tests and mathematical treatment used in this system would be less expensive to the industry and would result in a more accurate and comprehensive evaluation of the waste load than currently obtainable by methods specified in the monitoring regulations."
1237740,Weaver et al. 1977,Distribution of dichromate in preserved milk: Toward utilization of spent milk samples from centralized testing laboratories,"HEEP COPYRIGHT: BIOL ABS. The emergence of centralized milk testing laboratories brought with it the problem of disposing of large numbers of spent milk samples containing potassium dichromate preserative. Reduction of laboratory effluent biological O2 demand and conversion of this milk to a food or feed would be desirable. Edibility and safety of any recovered food or feed depend mainly on removal of the moderately toxic dichromate. A knowledge about the association of this hexavalent Cr with the major milk components is necessary. A ratiotracer study with 51Cr labeled sodium dichromate revealed 97.2% of the Cr in preserved milk was in the water phase while 2.8% was associated with the proteins, 2.2% with the casein and .6% with the whey proteins. Only a trace of the Cr was in the lipid fraction. An edible and acceptable buttermilk was produced from this milk. The Dairy Herd Improvement Association Laboratory at The Pennsylvania State University (USA) could generate about 400 kg of such otherwise wasted butteroil every month.","Distribution of dichromate in preserved milk: Toward utilization of spent milk samples from centralized testing laboratories Abs: HEEP COPYRIGHT: BIOL ABS. The emergence of centralized milk testing laboratories brought with it the problem of disposing of large numbers of spent milk samples containing potassium dichromate preserative. Reduction of laboratory effluent biological O2 demand and conversion of this milk to a food or feed would be desirable. Edibility and safety of any recovered food or feed depend mainly on removal of the moderately toxic dichromate. A knowledge about the association of this hexavalent Cr with the major milk components is necessary. A ratiotracer study with 51Cr labeled sodium dichromate revealed 97.2% of the Cr in preserved milk was in the water phase while 2.8% was associated with the proteins, 2.2% with the casein and .6% with the whey proteins. Only a trace of the Cr was in the lipid fraction. An edible and acceptable buttermilk was produced from this milk. The Dairy Herd Improvement Association Laboratory at The Pennsylvania State University (USA) could generate about 400 kg of such otherwise wasted butteroil every month."
1237736,Narasinga RAO et al. 1977,Absorption of chromium from chromium treated parboiled rice,"HEEP COPYRIGHT: BIOL ABS. The foul odor that develops in parboiled rice can be prevented by using sodium chromate (0.05%) in the steep water. It was observed that in this process, Cr content of parboiled rice increases 20-30 fold. The possible health hazard of Cr treated parboiled rice was investigated by carrying out Cr balance in human volunteers employing diets based on either Cr treated parboiled rice or untreated parboil rice. Absorption of Cr on diets based on untreated parboiled rice was about 60%. However, the absorption of additional Cr present in the parboiled rice treated with Cr was negligible. This observation was confirmed using parboiled rice treated with radioactive Cr. Additional Cr present in Cr treated parboiled rice may not pose any health hazard.","Absorption of chromium from chromium treated parboiled rice Abs: HEEP COPYRIGHT: BIOL ABS. The foul odor that develops in parboiled rice can be prevented by using sodium chromate (0.05%) in the steep water. It was observed that in this process, Cr content of parboiled rice increases 20-30 fold. The possible health hazard of Cr treated parboiled rice was investigated by carrying out Cr balance in human volunteers employing diets based on either Cr treated parboiled rice or untreated parboil rice. Absorption of Cr on diets based on untreated parboiled rice was about 60%. However, the absorption of additional Cr present in the parboiled rice treated with Cr was negligible. This observation was confirmed using parboiled rice treated with radioactive Cr. Additional Cr present in Cr treated parboiled rice may not pose any health hazard."
1237734,Fiussello and  Novo 1976,The effect of chromium on plants,"HEEP COPYRIGHT: BIOL ABS. Cr, as K2Cr2O7 and Cr(NO3)3, was tested for its toxicity, in Petri dishes, on 10 spp. of crop plants (Triticum vulgare, Phalaris canariensis, Pisum sativum, Hordeum vulgare, Secale cereale, Linum usitatissimum, Phaseolus vulgaris, Raphanus raphanistrum, Lycopersicon esculentum and Zea mays) at 1, 10 and 100 ppm. The total number of germinated seeds was not effected by Cr salts up to 100 ppm, but the toxicity measured as diminution of growth was evident in all plants at 100 ppm with Cr3+ and Cr6+. Cr6+ at 1 ppm had a negative effect on growth only for L. usitatissimum. Cr6+ was more toxic than Cr3+ for plants.","The effect of chromium on plants Abs: HEEP COPYRIGHT: BIOL ABS. Cr, as K2Cr2O7 and Cr(NO3)3, was tested for its toxicity, in Petri dishes, on 10 spp. of crop plants (Triticum vulgare, Phalaris canariensis, Pisum sativum, Hordeum vulgare, Secale cereale, Linum usitatissimum, Phaseolus vulgaris, Raphanus raphanistrum, Lycopersicon esculentum and Zea mays) at 1, 10 and 100 ppm. The total number of germinated seeds was not effected by Cr salts up to 100 ppm, but the toxicity measured as diminution of growth was evident in all plants at 100 ppm with Cr3+ and Cr6+. Cr6+ at 1 ppm had a negative effect on growth only for L. usitatissimum. Cr6+ was more toxic than Cr3+ for plants."
1237731,Cochran and  George 1976,Recovery of metals from a variety of industrial wastes,"HEEP COPYRIGHT: BIOL ABS. Bureau of Mines research on the development of practical processes for recovering metals and other materials from various industrial wastes is described. The work had a dual purpose: pollution abatement and conservation of scarce, costly materials. Electrochemical machining sludges were filtered to recover the electrolyte and smelted to produce valuable nickel-base alloys. Salable alloys were also produced by smelting stainless steel mill wastes. Shredded paper was used to reduce the hexavalent chromium in chromium etching wastes, after which Cu, Zn and chromium oxide were recovered as separate products. Electric furnace steelmaking dusts were pelletized with a reducing agent and heated to reduce zinc oxide and volatilize 98% or more of the Zn as metal.","Recovery of metals from a variety of industrial wastes Abs: HEEP COPYRIGHT: BIOL ABS. Bureau of Mines research on the development of practical processes for recovering metals and other materials from various industrial wastes is described. The work had a dual purpose: pollution abatement and conservation of scarce, costly materials. Electrochemical machining sludges were filtered to recover the electrolyte and smelted to produce valuable nickel-base alloys. Salable alloys were also produced by smelting stainless steel mill wastes. Shredded paper was used to reduce the hexavalent chromium in chromium etching wastes, after which Cu, Zn and chromium oxide were recovered as separate products. Electric furnace steelmaking dusts were pelletized with a reducing agent and heated to reduce zinc oxide and volatilize 98% or more of the Zn as metal."
1237730,Becker et al. 1976,CLINICAL FEATURE OF AN INTOXICATION OF POTASSIUM DI CHROMATE TREATED BY HEMO DIALYSIS,HEEP COPYRIGHT: BIOL ABS. HUMAN SUICIDE DISSEMINATED INTRA VASCULAR COAGULATION ACUTE RENAL FAILURE LIVER DISEASE,CLINICAL FEATURE OF AN INTOXICATION OF POTASSIUM DI CHROMATE TREATED BY HEMO DIALYSIS Abs: HEEP COPYRIGHT: BIOL ABS. HUMAN SUICIDE DISSEMINATED INTRA VASCULAR COAGULATION ACUTE RENAL FAILURE LIVER DISEASE
1237729,Kogan YU 1976,Effect of intervals between doses of potassium bichromate on the state of the renal parenchyma and mortality in albino mice,"The state of the tubular apparatus of the kidney was studied in 360 albino mice receiving frequent subcutaneous injections of potassium bicromate at intervals of 1 day, 1 week, or 1 month. More frequent administration of the toxic agent was shown to give rise to a lower mortality among the animals and to have a milder toxic action on the tubular apparatus.","Effect of intervals between doses of potassium bichromate on the state of the renal parenchyma and mortality in albino mice Abs: The state of the tubular apparatus of the kidney was studied in 360 albino mice receiving frequent subcutaneous injections of potassium bicromate at intervals of 1 day, 1 week, or 1 month. More frequent administration of the toxic agent was shown to give rise to a lower mortality among the animals and to have a milder toxic action on the tubular apparatus."
1237727,Bigaliev et al. 1976,Chromosome aberrations induced in mammalian somatic cells by chromium compounds,,Chromosome aberrations induced in mammalian somatic cells by chromium compounds Abs: 
1237726,Oshida and  Wright 1976,ACUTE RESPONSES OF MARINE INVERTEBRATES TO CHROMIUM,HEEP COPYRIGHT: BIOL ABS. OPHIOTHRIX-SPICULATA SICYONIA-INGENTIS THEMISTE-SP HEXAVALENT TRIVALENT POTASSIUM DI CHROMATE CHROMIC CHLORIDE ABSORPTION SURVIVAL BEHAVIOR REPRODUCTION,ACUTE RESPONSES OF MARINE INVERTEBRATES TO CHROMIUM Abs: HEEP COPYRIGHT: BIOL ABS. OPHIOTHRIX-SPICULATA SICYONIA-INGENTIS THEMISTE-SP HEXAVALENT TRIVALENT POTASSIUM DI CHROMATE CHROMIC CHLORIDE ABSORPTION SURVIVAL BEHAVIOR REPRODUCTION
1237724,Kennedy G L et al. 1976,TOXICITY OF LEAD CHROMATE PIGMENTS AND TISSUE RESIDUES FOLLOWING 90 DAYS FEEDING TO ALBINO RATS,HEEP COPYRIGHT: BIOL ABS. ABSTRACT TOXICITY METABOLISM URINARY EXCRETION BLOOD STUDIES,TOXICITY OF LEAD CHROMATE PIGMENTS AND TISSUE RESIDUES FOLLOWING 90 DAYS FEEDING TO ALBINO RATS Abs: HEEP COPYRIGHT: BIOL ABS. ABSTRACT TOXICITY METABOLISM URINARY EXCRETION BLOOD STUDIES
1237723,Hook and  Stroo 1976,ENZYMES OF RENAL ORIGIN IN URINE AS INDICATORS OF NEPHRO TOXICITY,HEEP COPYRIGHT: BIOL ABS. ABSTRACT RAT MERCURIC CHLORIDE POTASSIUM DI CHROMATE INTRA PERITONEAL ADMINISTRATION MALTASE ALKALINE PHOSPHATASE,ENZYMES OF RENAL ORIGIN IN URINE AS INDICATORS OF NEPHRO TOXICITY Abs: HEEP COPYRIGHT: BIOL ABS. ABSTRACT RAT MERCURIC CHLORIDE POTASSIUM DI CHROMATE INTRA PERITONEAL ADMINISTRATION MALTASE ALKALINE PHOSPHATASE
1237722,Skeffington et al. 1976,Chromium uptake and transport in barley seedlings (Hordeum vulgare L.),"HEEP COPYRIGHT: BIOL ABS. Potassium chromate is more toxic to the growth of barley in solution culture than chromic chloride, though apparent uptake of the latter is much faster. Inhibitor studies indicate that CrO42- uptake is active whereas Cr3+ uptake is passive, demonstrating that the 2 forms do not share a common uptake mechanism. Studies on the form of Cr inside root cells show that in plants fed CrO42- the Cr remains largely unchanged whereas in plants fed Cr3+ a little CrO42- (0.5%) is produced. This conversion is dependent on the presence of living material and is probably enzymatic. Chromate uptake follows Michaelis-Menten kinetics at low concentration and is competitively inhibited by sulfate. Transport of Cr up the root is very slow, accounting for the low levels of Cr in the shoots. Chromate is transported better than Cr3+ though still to a very limited extent. These experiments provide a physiological basis for previous observations.","Chromium uptake and transport in barley seedlings (Hordeum vulgare L.) Abs: HEEP COPYRIGHT: BIOL ABS. Potassium chromate is more toxic to the growth of barley in solution culture than chromic chloride, though apparent uptake of the latter is much faster. Inhibitor studies indicate that CrO42- uptake is active whereas Cr3+ uptake is passive, demonstrating that the 2 forms do not share a common uptake mechanism. Studies on the form of Cr inside root cells show that in plants fed CrO42- the Cr remains largely unchanged whereas in plants fed Cr3+ a little CrO42- (0.5%) is produced. This conversion is dependent on the presence of living material and is probably enzymatic. Chromate uptake follows Michaelis-Menten kinetics at low concentration and is competitively inhibited by sulfate. Transport of Cr up the root is very slow, accounting for the low levels of Cr in the shoots. Chromate is transported better than Cr3+ though still to a very limited extent. These experiments provide a physiological basis for previous observations."
1237721,Kogan YU 1976,The effect of the pattern of potassium bichromate administration on the state of the renal parenchyma and its lethality for albino mice,"HEEP COPYRIGHT: BIOL ABS. A study was made of the state of the tubular apparatus in 360 albino mice given repeated s.c. injections of potassium bichromate with intervals of 1 day, 1 wk and 1 mo. A more frequent action of the pathogenic agent proved to lead to less lethality and produced less toxicity of the renal tubules.","The effect of the pattern of potassium bichromate administration on the state of the renal parenchyma and its lethality for albino mice Abs: HEEP COPYRIGHT: BIOL ABS. A study was made of the state of the tubular apparatus in 360 albino mice given repeated s.c. injections of potassium bichromate with intervals of 1 day, 1 wk and 1 mo. A more frequent action of the pathogenic agent proved to lead to less lethality and produced less toxicity of the renal tubules."
1237715,Urdabaev ZH 1975,Pathomorphology of experimental chromic ulcer of the skin,"HEEP COPYRIGHT: BIOL ABS. Dynamics of morphological and some histochemical changes were shown on an experimental model of chromic ulcer of the skin (25 guinea pigs). On the previously epilated and scarified skin of animals consisting of 4 groups (5 animals in each group) applications of chromic alkali with various concentrations of bichromates of K and Na were made; biopsy specimens were taken at 1, 4, 7, 10, 15, 20, 25 and 30 days. The results obtained made it possible to identify 4 stages in the development of chromic ulcer (prenecrotic, necrotic, chromic ulcer, healing), each stage being characterized by its own peculiar features of the clinical course and morphological changes.","Pathomorphology of experimental chromic ulcer of the skin Abs: HEEP COPYRIGHT: BIOL ABS. Dynamics of morphological and some histochemical changes were shown on an experimental model of chromic ulcer of the skin (25 guinea pigs). On the previously epilated and scarified skin of animals consisting of 4 groups (5 animals in each group) applications of chromic alkali with various concentrations of bichromates of K and Na were made; biopsy specimens were taken at 1, 4, 7, 10, 15, 20, 25 and 30 days. The results obtained made it possible to identify 4 stages in the development of chromic ulcer (prenecrotic, necrotic, chromic ulcer, healing), each stage being characterized by its own peculiar features of the clinical course and morphological changes."
1237714,Duengemann 1975,METAL ALLERGIES AND THEIR SIGNIFICANCE TO ACCIDENT PRACTICE CLINICAL EXPERIENCE WITH THE MOST IMPORTANT MANIFESTATIONS INCLUDING ASTHMA UNDER THE SUPERVISION OF DERMATOLOGISTS INTERNISTS AND SURGEONS,HEEP COPYRIGHT: BIOL ABS. HUMAN OCCUPATIONAL EXPOSURE POTASSIUM BI CHROMATE COBALT SULFATE NICKEL SULFATE CADMIUM SULFATE TURPENTINE HEXAMETHYLENE TETRAMINE COPPER SULFATE ECZEMA INTRA CUTANEOUS TESTING,METAL ALLERGIES AND THEIR SIGNIFICANCE TO ACCIDENT PRACTICE CLINICAL EXPERIENCE WITH THE MOST IMPORTANT MANIFESTATIONS INCLUDING ASTHMA UNDER THE SUPERVISION OF DERMATOLOGISTS INTERNISTS AND SURGEONS Abs: HEEP COPYRIGHT: BIOL ABS. HUMAN OCCUPATIONAL EXPOSURE POTASSIUM BI CHROMATE COBALT SULFATE NICKEL SULFATE CADMIUM SULFATE TURPENTINE HEXAMETHYLENE TETRAMINE COPPER SULFATE ECZEMA INTRA CUTANEOUS TESTING
1237713,Berndt 1975,Effects of anoxia on renal transport processes,HEEP COPYRIGHT: BIOL ABS. ABSTRACT RAT POTASSIUM DI CHROMATE NEPHRO TOXIN,Effects of anoxia on renal transport processes Abs: HEEP COPYRIGHT: BIOL ABS. ABSTRACT RAT POTASSIUM DI CHROMATE NEPHRO TOXIN
1237711,Ado and  Horyachkina 1975,Modeling of chemical allergoses and their selective and nonspecific inhibition,"HEEP COPYRIGHT: BIOL ABS. The possibility of sensitization of guinea pigs, hamsters and rabbits by such chemical allergens as 2,4-dinitrochlorobenzene, picryl chloride, dinitrofluorobenzene, arsenic compounds, combined substances (nitrophenol + bovine gamma-globulin, dinitrophenol + bovine fibrinogen), native and denatured proteins, potassium bichromate, cobaltous nitrate and nickel chloride was investigated. Also investigated was the possibility of nonspecific inhibition of allergic reactions by alkylating agents, antimetabolites, cytostatics, inhibitors of cell enzymes, immunosuppressive antibiotics, hormonal preparations and folic acid antagonists. The possibility, in principle, of both nonspecific and specific regulation of the levels of chemical allergens was discussed, since increasingly more chemical preparations both specifically inhibiting and intensifying the induction of the development of such chemical allergoses are presently being synthesized.","Modeling of chemical allergoses and their selective and nonspecific inhibition Abs: HEEP COPYRIGHT: BIOL ABS. The possibility of sensitization of guinea pigs, hamsters and rabbits by such chemical allergens as 2,4-dinitrochlorobenzene, picryl chloride, dinitrofluorobenzene, arsenic compounds, combined substances (nitrophenol + bovine gamma-globulin, dinitrophenol + bovine fibrinogen), native and denatured proteins, potassium bichromate, cobaltous nitrate and nickel chloride was investigated. Also investigated was the possibility of nonspecific inhibition of allergic reactions by alkylating agents, antimetabolites, cytostatics, inhibitors of cell enzymes, immunosuppressive antibiotics, hormonal preparations and folic acid antagonists. The possibility, in principle, of both nonspecific and specific regulation of the levels of chemical allergens was discussed, since increasingly more chemical preparations both specifically inhibiting and intensifying the induction of the development of such chemical allergoses are presently being synthesized."
1237710,Chaisemartin 1975,Effects of chromates (K2CrO4) on respiratory metabolism and tissue water-mineral balance in larvae of 2 species from freshwater macrobenthos,"HEEP COPYRIGHT: BIOL ABS. Toxic effects of hexavalent Cr compounds (chromates, pollutants) and information on their mechanisms of action on larvae of aquatic insects (Ecdyonurus and Sympetrum spp.) were studied. Studies of O2 consumption were conducted to elucidate some of the interactions among respiration, osmoregulation and chromate toxicity. The death rate increased with increasing concentration. The time/mortality curve is a repeating pattern of slow rate followed by an increasing rate of mortality. At 0.05 ppm Cr, the high density increased the mortality rate. Between 0.05-0.1 ppm, a threshold is reached where any further decrease in density does not increase the chances of survival. Metabolic rate, which affects the response of animals to toxic substances, is in turn affected by animal density. Especially with Ecdyonurus, the area of concentrations between 0.05-0.1 ppm of Cr-6+ is a threshold at which the physiological responses of the animals undergo a change.","Effects of chromates (K2CrO4) on respiratory metabolism and tissue water-mineral balance in larvae of 2 species from freshwater macrobenthos Abs: HEEP COPYRIGHT: BIOL ABS. Toxic effects of hexavalent Cr compounds (chromates, pollutants) and information on their mechanisms of action on larvae of aquatic insects (Ecdyonurus and Sympetrum spp.) were studied. Studies of O2 consumption were conducted to elucidate some of the interactions among respiration, osmoregulation and chromate toxicity. The death rate increased with increasing concentration. The time/mortality curve is a repeating pattern of slow rate followed by an increasing rate of mortality. At 0.05 ppm Cr, the high density increased the mortality rate. Between 0.05-0.1 ppm, a threshold is reached where any further decrease in density does not increase the chances of survival. Metabolic rate, which affects the response of animals to toxic substances, is in turn affected by animal density. Especially with Ecdyonurus, the area of concentrations between 0.05-0.1 ppm of Cr-6+ is a threshold at which the physiological responses of the animals undergo a change."
1237709,Saltzman et al. 1975,Continuous monitoring instrument for reactive hydrocarbons in ambient air,"HEEP COPYRIGHT: BIOL ABS. A modification of a total hydrocarbon analyzer made it capable of simultaneously monitoring ambient air for reactive hydrocarbons with the potential for producing photochemical smog. Matered sample air flows were continuously pumped through an empty column and an absorbent column arranged in parallel. The air stream existing from each column was directed alternatively in a 5-min cycle by a switching valve to the flame ionization detector for quantitative measurements. A chromium trioxide-sulfuric acid packing was optimal to absorb olefinic and higher aromatic hydrocarbons, and suitable column dimensions, flow rates and temperatures were determined to obtain desired separations. Reactive hydrocarbon concentrations, obtained by difference from the instrument recordings, are reported for Cincinnati, Ohio, USA. These measurements should be more relevant than those of total or nonmethane hydrocarbons.","Continuous monitoring instrument for reactive hydrocarbons in ambient air Abs: HEEP COPYRIGHT: BIOL ABS. A modification of a total hydrocarbon analyzer made it capable of simultaneously monitoring ambient air for reactive hydrocarbons with the potential for producing photochemical smog. Matered sample air flows were continuously pumped through an empty column and an absorbent column arranged in parallel. The air stream existing from each column was directed alternatively in a 5-min cycle by a switching valve to the flame ionization detector for quantitative measurements. A chromium trioxide-sulfuric acid packing was optimal to absorb olefinic and higher aromatic hydrocarbons, and suitable column dimensions, flow rates and temperatures were determined to obtain desired separations. Reactive hydrocarbon concentrations, obtained by difference from the instrument recordings, are reported for Cincinnati, Ohio, USA. These measurements should be more relevant than those of total or nonmethane hydrocarbons."
1237707,Perry and  Matson 1975,ZINC AND CHROMATE REDUCTION BY LIME SOFTENING OF COOLING TOWER BLOWDOWN,HEEP COPYRIGHT: BIOL ABS.,ZINC AND CHROMATE REDUCTION BY LIME SOFTENING OF COOLING TOWER BLOWDOWN Abs: HEEP COPYRIGHT: BIOL ABS.
1237703,Ferro MILONE et al. 1974,MORPHOLOGICAL AND FUNCTIONAL KIDNEY ALTERATIONS INDUCED IN LABORATORY ANIMALS BY SOME NEPHRO TOXIC AGENTS,HEEP COPYRIGHT: BIOL ABS.,MORPHOLOGICAL AND FUNCTIONAL KIDNEY ALTERATIONS INDUCED IN LABORATORY ANIMALS BY SOME NEPHRO TOXIC AGENTS Abs: HEEP COPYRIGHT: BIOL ABS.
1237700,Shakhnazarov et al. 1974,"Cytochemical analysis of alkaline phosphatase, acid phosphatase and glycogen in the peripheral blood leukocytes of workers engaged in chromium compound production","HEEP COPYRIGHT: BIOL ABS. In 130 workers (78 males, 52 females) engaged in production of potassium bichromate for periods ranging from 3 mo.-25 yr cytochemical investigations were made of the alkaline, acid phosphatases and glycogen in leukocytes of the peripheral blood. As controls 20 persons not exposed to the effects of Cr compounds were examined. Cytochemical changes in the leukocytes were phasic. In the 1st period (service-record up to 5 yr) high activity of alkaline and acid phosphatases and a considerable glycogen level were noted. In the 2nd period (service record of more than 10 yr) depletion of glycogen reserves and inhibition of enzyme activity set in. The alkaline and acid phosphatases activity and glycogen content in the peripheral blood leukocytes depend not only on the service record and general occupational poisoning, but also on the nature of the occupational disease.","Cytochemical analysis of alkaline phosphatase, acid phosphatase and glycogen in the peripheral blood leukocytes of workers engaged in chromium compound production Abs: HEEP COPYRIGHT: BIOL ABS. In 130 workers (78 males, 52 females) engaged in production of potassium bichromate for periods ranging from 3 mo.-25 yr cytochemical investigations were made of the alkaline, acid phosphatases and glycogen in leukocytes of the peripheral blood. As controls 20 persons not exposed to the effects of Cr compounds were examined. Cytochemical changes in the leukocytes were phasic. In the 1st period (service-record up to 5 yr) high activity of alkaline and acid phosphatases and a considerable glycogen level were noted. In the 2nd period (service record of more than 10 yr) depletion of glycogen reserves and inhibition of enzyme activity set in. The alkaline and acid phosphatases activity and glycogen content in the peripheral blood leukocytes depend not only on the service record and general occupational poisoning, but also on the nature of the occupational disease."
1237699,Skripkin YU et al. 1974,Occupational allergic dermatoses in electroplating workers,"HEEP COPYRIGHT: BIOL ABS. The results of a study of the allergic reactivity of patients with dermatits and eczema from the effect of electroplating solutions of chromium trioxide, ammonium bichromate, nickel sulfate, chromic oxide and potassium gold cyanide are presented. Considerable occupational pathology of the skin in electroplating workers resulted from the sensitizing effect of Cr, Ni and gold cyanide compounds. Effective prevention of occupational dermatoses in these workers can be achieved by automation and mechanization of the plating processes, as well as sanitary-engineering, hygienic and individual prophylatic means.","Occupational allergic dermatoses in electroplating workers Abs: HEEP COPYRIGHT: BIOL ABS. The results of a study of the allergic reactivity of patients with dermatits and eczema from the effect of electroplating solutions of chromium trioxide, ammonium bichromate, nickel sulfate, chromic oxide and potassium gold cyanide are presented. Considerable occupational pathology of the skin in electroplating workers resulted from the sensitizing effect of Cr, Ni and gold cyanide compounds. Effective prevention of occupational dermatoses in these workers can be achieved by automation and mechanization of the plating processes, as well as sanitary-engineering, hygienic and individual prophylatic means."
1237698,Severs 1974,Simultaneous total oxidant and chemiluminescent ozone measurements in ambient air,"HEEP COPYRIGHT: BIOL ABS. The relationship of ambient air quality measurements between 2 analytical methods, referred to as the total oxidant method and the chemiluminescent method, was investigated. These 2 well documented analytical methods were run simultaneously, side by side, at a site on the Houston, Texas, USA ship channel. They were calibrated daily. The hourly averages were analyzed by regression techniques and the confidence intervals were calculated for the regression lines. Confidence intervals for point estimates were also calculated. These methods were used with all data sets with values greater than 10 ppb and again with values greater than 30 ppb. A regression line was also calculated for a 2nd set of data for the preceding year. These data were generated before a chromium trioxide scrubber was installed to eliminate possible chemical interferences with the KI method. In general the chemiluminescent ozone method tends to produce values as much as 2 times higher than the simultaneous total oxidant values. In 1 set of data collected an 80 ppb chemiluminescent ozone value predicted a value of 43.9 ppb total oxidant with a 95% confidence interval of 7.7-80.4 ppb. In the 2nd set of data an 80 ppb chemiluminescent ozone value predicted a value of 78 ppb total oxidant with a 95% confidence interval of 0.4-156 ppb. Other statistical analyses confirmed that either measurement was a very poor predictor of the other.","Simultaneous total oxidant and chemiluminescent ozone measurements in ambient air Abs: HEEP COPYRIGHT: BIOL ABS. The relationship of ambient air quality measurements between 2 analytical methods, referred to as the total oxidant method and the chemiluminescent method, was investigated. These 2 well documented analytical methods were run simultaneously, side by side, at a site on the Houston, Texas, USA ship channel. They were calibrated daily. The hourly averages were analyzed by regression techniques and the confidence intervals were calculated for the regression lines. Confidence intervals for point estimates were also calculated. These methods were used with all data sets with values greater than 10 ppb and again with values greater than 30 ppb. A regression line was also calculated for a 2nd set of data for the preceding year. These data were generated before a chromium trioxide scrubber was installed to eliminate possible chemical interferences with the KI method. In general the chemiluminescent ozone method tends to produce values as much as 2 times higher than the simultaneous total oxidant values. In 1 set of data collected an 80 ppb chemiluminescent ozone value predicted a value of 43.9 ppb total oxidant with a 95% confidence interval of 7.7-80.4 ppb. In the 2nd set of data an 80 ppb chemiluminescent ozone value predicted a value of 78 ppb total oxidant with a 95% confidence interval of 0.4-156 ppb. Other statistical analyses confirmed that either measurement was a very poor predictor of the other."
1237693,Norpoth et al. 1974,Induction of microsomal hemoproteins in the liver of rats after ingestion of inorganic lead compounds,"HEEP COPYRIGHT: BIOL ABS. High doses of inorganic lead compounds were given per os to male Wistar rats. The aim was to study the effect of Pb on the induction by phenobarbital of the hepatic hemoproteins cytochrome P450 and cytochrome b5. Daily amounts of 6.0-43.75 mg of lead acetate, lead nitrate, lead chromate, lead chloride, lead carbonate or lead sulfate were given on 4 consecutive days; on day 2 each animal received 100 mg/kg phenobarbital i.p. After the 4-day period the animals were killed and the content of cytochrome P450 and cytochrome b5 in the liver was determined. The activity of aminopyrine demethylase in the microsomal fraction of hepatic tissue was also measured, and the lead content of the livers and blood Hb were determined. The induction of cytochrome P450 and aminopyrine demethylase seemed to be stimulated by lead chloride and depressed by lead acetate. Lead chloride, however, has no effect when given without phenobarbital. In a futher experiment, lead acetate, in a daily dose of 30 mg for 4 days, failed to inhibit enzyme induction. The lead content of livers of rats receiving this dose of lead acetate was 4 times that in control rats. Similar levels were found after oral treatment with other Pb compounds. Values for body weight, liver weight, microsomal protein and blood Hb were not influenced. Short-term toxic doses of different inorganic lead compounds do not exert an inhibitory influence on the porphyrin synthesis stimulated in the rat liver by phenobarbital. The findings do not exclude the possiblity that this mechanism of inhibition may occur, and it could be important in connection with other kinds of Pb intoxication.","Induction of microsomal hemoproteins in the liver of rats after ingestion of inorganic lead compounds Abs: HEEP COPYRIGHT: BIOL ABS. High doses of inorganic lead compounds were given per os to male Wistar rats. The aim was to study the effect of Pb on the induction by phenobarbital of the hepatic hemoproteins cytochrome P450 and cytochrome b5. Daily amounts of 6.0-43.75 mg of lead acetate, lead nitrate, lead chromate, lead chloride, lead carbonate or lead sulfate were given on 4 consecutive days; on day 2 each animal received 100 mg/kg phenobarbital i.p. After the 4-day period the animals were killed and the content of cytochrome P450 and cytochrome b5 in the liver was determined. The activity of aminopyrine demethylase in the microsomal fraction of hepatic tissue was also measured, and the lead content of the livers and blood Hb were determined. The induction of cytochrome P450 and aminopyrine demethylase seemed to be stimulated by lead chloride and depressed by lead acetate. Lead chloride, however, has no effect when given without phenobarbital. In a futher experiment, lead acetate, in a daily dose of 30 mg for 4 days, failed to inhibit enzyme induction. The lead content of livers of rats receiving this dose of lead acetate was 4 times that in control rats. Similar levels were found after oral treatment with other Pb compounds. Values for body weight, liver weight, microsomal protein and blood Hb were not influenced. Short-term toxic doses of different inorganic lead compounds do not exert an inhibitory influence on the porphyrin synthesis stimulated in the rat liver by phenobarbital. The findings do not exclude the possiblity that this mechanism of inhibition may occur, and it could be important in connection with other kinds of Pb intoxication."
1237688,Perepelitsa 1973,ACUTE POTASSIUM BI CHROMATE POISONING,HEEP COPYRIGHT: BIOL ABS. NAUSEA VOMITING STOMACH LAVAGE ANTI SHOCK DRUGS,ACUTE POTASSIUM BI CHROMATE POISONING Abs: HEEP COPYRIGHT: BIOL ABS. NAUSEA VOMITING STOMACH LAVAGE ANTI SHOCK DRUGS
1237687,Saraiva 1973,Rapid toxicity test by the measurement of dissolved oxygen using the polarographic method: Action of some metals on Dunaliella and Lebistes,"HEEP COPYRIGHT: BIOL ABS. Measurements of respiration and photosynthesis in Dunaliella by the polarographic method are made to determine the acute toxicity of several metals. The O2 consumption of Libistes is also measured by this method. The use of a polarographic oxygen electrode, in studies of industrial wastes for small fishes or other aquatic animals and algae, may provide preliminary information.","Rapid toxicity test by the measurement of dissolved oxygen using the polarographic method: Action of some metals on Dunaliella and Lebistes Abs: HEEP COPYRIGHT: BIOL ABS. Measurements of respiration and photosynthesis in Dunaliella by the polarographic method are made to determine the acute toxicity of several metals. The O2 consumption of Libistes is also measured by this method. The use of a polarographic oxygen electrode, in studies of industrial wastes for small fishes or other aquatic animals and algae, may provide preliminary information."
1237686,Loechel et al. 1973,STUDIES ON ANIMAL EXPERIMENTAL MODELS FOR THE DETERMINATION OF THE SENSITIZING POWER OF CHEMICAL COMPOUNDS PART 1 DETERMINATION OF THE SENSITIZING POWER OF POTASSIUM CHROMATE UNDER DIFFERENT CONDITIONS,HEEP COPYRIGHT: BIOL ABS. GUINEA-PIG ECZEMA LYMPHOCYTE TRANSFORMATION SPLEEN CELL TRANSFER,STUDIES ON ANIMAL EXPERIMENTAL MODELS FOR THE DETERMINATION OF THE SENSITIZING POWER OF CHEMICAL COMPOUNDS PART 1 DETERMINATION OF THE SENSITIZING POWER OF POTASSIUM CHROMATE UNDER DIFFERENT CONDITIONS Abs: HEEP COPYRIGHT: BIOL ABS. GUINEA-PIG ECZEMA LYMPHOCYTE TRANSFORMATION SPLEEN CELL TRANSFER
1237685,Eberhartinger 1973,Housewife's eczema,"HEEP COPYRIGHT: BIOL ABS. The toxic degenerative form is the most common housewife's eczema. The protection function of the skin consists of non-soluble polymeric structures of keratin, cell membranes and intercellular substances, the water-soluble components of the corneum and the epidermogenic corneal lipids. Modern detergents extract lipids, dissolve the water-soluble micromolecular epidermal components and denature the keratin, especially polyphosphate-containing detergents. Peruvian balsam is the most common cause of allergic contact eczema, but nickel, turpentine, Cr, formalin and rubber ingredients are also prevalent. An epicutaneous ""lobule test"" using a pure substance such as potassium dichromate or nickel sulfate is necessary to differentiate between the 2 forms, since only skin care is required in the 1st type, but contact with the specific allergen is to be avoided in the 2nd. Asthmatoid conditions and eczematous skin changes have occurred in workers at factories which produce enzyme-containing detergents and these were diminished by increasing particle size, but there is no experimental evidence that these detergent proteases cause skin sensitization in humans.","Housewife's eczema Abs: HEEP COPYRIGHT: BIOL ABS. The toxic degenerative form is the most common housewife's eczema. The protection function of the skin consists of non-soluble polymeric structures of keratin, cell membranes and intercellular substances, the water-soluble components of the corneum and the epidermogenic corneal lipids. Modern detergents extract lipids, dissolve the water-soluble micromolecular epidermal components and denature the keratin, especially polyphosphate-containing detergents. Peruvian balsam is the most common cause of allergic contact eczema, but nickel, turpentine, Cr, formalin and rubber ingredients are also prevalent. An epicutaneous ""lobule test"" using a pure substance such as potassium dichromate or nickel sulfate is necessary to differentiate between the 2 forms, since only skin care is required in the 1st type, but contact with the specific allergen is to be avoided in the 2nd. Asthmatoid conditions and eczematous skin changes have occurred in workers at factories which produce enzyme-containing detergents and these were diminished by increasing particle size, but there is no experimental evidence that these detergent proteases cause skin sensitization in humans."
1237681,Shmunes et al. 1973,Chromium-amino acid conjugates as elicitors in chromium-sensitized guinea pigs,HEEP COPYRIGHT: BIOL ABS. Chromium-amino acid conjugates were isolated from systems initially containing either potassium dichromate and amino acid or chromic nitrate and amino acid. The elicitating properties of these chromium-amino acid conjugates were evaluated by intradermal injection of guinea pigs sensitized to chromium. Positive results were obtained with several conjugates. The conjugates prepared from chromic nitrate and amino acid were stronger elicitors than those prepared from potassium dichromate and amino acid.,Chromium-amino acid conjugates as elicitors in chromium-sensitized guinea pigs Abs: HEEP COPYRIGHT: BIOL ABS. Chromium-amino acid conjugates were isolated from systems initially containing either potassium dichromate and amino acid or chromic nitrate and amino acid. The elicitating properties of these chromium-amino acid conjugates were evaluated by intradermal injection of guinea pigs sensitized to chromium. Positive results were obtained with several conjugates. The conjugates prepared from chromic nitrate and amino acid were stronger elicitors than those prepared from potassium dichromate and amino acid.
1237680,Ziegler et al. 1972,The guinea-pig maximization test to demonstrate the sensitization effect of important industrial products,"HEEP COPYRIGHT: BIOL ABS. Sensitization experiments on mixed bred animals and inbred animals with chromates, TMTD (tetramethylthiuramdisulfite), mercaptobenzothiazole and thioplast by means of a maximization test were reported. While the experiments with TMTD, mercaptobenzothiazole and thioplast showed the sensitization rates expected, the results with the frequent industrial allergen potassium bichromate were negative. Problems of concentration, of the temporary course of sensitiziation and exposure methods are discussed as causes from the negative findings in chromates.","The guinea-pig maximization test to demonstrate the sensitization effect of important industrial products Abs: HEEP COPYRIGHT: BIOL ABS. Sensitization experiments on mixed bred animals and inbred animals with chromates, TMTD (tetramethylthiuramdisulfite), mercaptobenzothiazole and thioplast by means of a maximization test were reported. While the experiments with TMTD, mercaptobenzothiazole and thioplast showed the sensitization rates expected, the results with the frequent industrial allergen potassium bichromate were negative. Problems of concentration, of the temporary course of sensitiziation and exposure methods are discussed as causes from the negative findings in chromates."
1237679,Lamba 1972,Food poisoning: Some epidemiological aspects,"HEEP COPYRIGHT: BIOL ABS. Nine outbreaks of food poisoning involving 283 persons, 7 of the toxin type, 1 infectious, and 1 involving chemical intoxication, are discussed. With the exception of 2 all outbreaks occurred due to neglect of normal precautions at unit level. Two outbreaks are attributed to canned foods contaminated at source by faulty processing. Chemical food poisoning due to potassium dichromate occurred by the use of unauthorized coloring material. Rigid enforcement of hygiene rules in food inspection, handling and storage for prevention of such food poisoning episodes is stressed.","Food poisoning: Some epidemiological aspects Abs: HEEP COPYRIGHT: BIOL ABS. Nine outbreaks of food poisoning involving 283 persons, 7 of the toxin type, 1 infectious, and 1 involving chemical intoxication, are discussed. With the exception of 2 all outbreaks occurred due to neglect of normal precautions at unit level. Two outbreaks are attributed to canned foods contaminated at source by faulty processing. Chemical food poisoning due to potassium dichromate occurred by the use of unauthorized coloring material. Rigid enforcement of hygiene rules in food inspection, handling and storage for prevention of such food poisoning episodes is stressed."
1237678,Cronin 1972,Contact dermatitis: XVII. Reactions to contact allergens given orally or systemically,"Ingestion of a contact allergen in a sensitized person can cause dermatitis. The allergens include drugs, antibiotics, food dyes, paraphenylenediamine, thiuram chemicals, food flavorings, Cr and pentadecylcatechol. Striking features of many of the case reports are the rapid onset, within hours, of the effect of the oral or systemic antigen and when the effect is severe, the systemic upset experienced by the patient. Such rapidity of response suggests that an immediate rather than a delayed type hypersensitivity may be partly or entirely responsible. In some subjects the ingestion or systemic administration of an allergen can cause both eczema and systemic effects; equally in other patients no reaction occurs.","Contact dermatitis: XVII. Reactions to contact allergens given orally or systemically Abs: Ingestion of a contact allergen in a sensitized person can cause dermatitis. The allergens include drugs, antibiotics, food dyes, paraphenylenediamine, thiuram chemicals, food flavorings, Cr and pentadecylcatechol. Striking features of many of the case reports are the rapid onset, within hours, of the effect of the oral or systemic antigen and when the effect is severe, the systemic upset experienced by the patient. Such rapidity of response suggests that an immediate rather than a delayed type hypersensitivity may be partly or entirely responsible. In some subjects the ingestion or systemic administration of an allergen can cause both eczema and systemic effects; equally in other patients no reaction occurs."
1237677,Jones and  Warner 1972,"Chronic exposure to iron oxide, chromium oxide, and nickel oxide fumes of metal dressers in a steelworks","HEEP COPYRIGHT: BIOL ABS. Occupational and medical histories, smoking habits, respiratory symptoms, chest radiographs and ventilatory capacities were studied in 14 steelworkers employed as deseamers of steel ingots for periods of up to 16 yr. The men were exposed for approximately 5 hr of each working shift to fume concentrations ranging from 1.3-294.1 mg/m-3 made up mainly of iron oxide with varying proportions of chromium oxide and nickel oxide. Four of the men, with 14-16 yr exposure, showed radiological evidence of pneumoconiosis classified as International Labour Office categories 2 or 3. Of these, 2 had pulmonary function within the normal range and 2 had measurable loss of function, moderate in 1 case and mild in the other. Many observers would diagnose these cases as siderosis but recommendations are made that this term be reserved for cases exposed to pure Fe compounds. The correct diagnosis is mixed-dust pneumoconiosis and the loss of pulmonary function is caused by the effects of the mixture of metallic oxides. Inhalation of pure iron oxide probably does not cause fibrotic pulmonary changes, whereas the inhalation of iron oxide plus certain other substances obviously does.","Chronic exposure to iron oxide, chromium oxide, and nickel oxide fumes of metal dressers in a steelworks Abs: HEEP COPYRIGHT: BIOL ABS. Occupational and medical histories, smoking habits, respiratory symptoms, chest radiographs and ventilatory capacities were studied in 14 steelworkers employed as deseamers of steel ingots for periods of up to 16 yr. The men were exposed for approximately 5 hr of each working shift to fume concentrations ranging from 1.3-294.1 mg/m-3 made up mainly of iron oxide with varying proportions of chromium oxide and nickel oxide. Four of the men, with 14-16 yr exposure, showed radiological evidence of pneumoconiosis classified as International Labour Office categories 2 or 3. Of these, 2 had pulmonary function within the normal range and 2 had measurable loss of function, moderate in 1 case and mild in the other. Many observers would diagnose these cases as siderosis but recommendations are made that this term be reserved for cases exposed to pure Fe compounds. The correct diagnosis is mixed-dust pneumoconiosis and the loss of pulmonary function is caused by the effects of the mixture of metallic oxides. Inhalation of pure iron oxide probably does not cause fibrotic pulmonary changes, whereas the inhalation of iron oxide plus certain other substances obviously does."
1237674,Helle 1972,Urticaria in chromate allergy,"HEEP COPYRIGHT: BIOL ABS. Though chromate allergy is well known as an occupational hazard in many industries, the case reported here is more unusual in that it concerns Cr sensitivity in a Cr-Co dental prosthesis worn by an elderly patient. The woman's urticaria disappeared every time she stopped wearing the prosthesis and returned every time she wore it again. She also reacted very strongly to an intradermal test with dilute potassium chromate. The patient improved after the metal parts of the prosthesis were Au-plated, but a later test showed that she was still allergic to Cr and also to Co.","Urticaria in chromate allergy Abs: HEEP COPYRIGHT: BIOL ABS. Though chromate allergy is well known as an occupational hazard in many industries, the case reported here is more unusual in that it concerns Cr sensitivity in a Cr-Co dental prosthesis worn by an elderly patient. The woman's urticaria disappeared every time she stopped wearing the prosthesis and returned every time she wore it again. She also reacted very strongly to an intradermal test with dilute potassium chromate. The patient improved after the metal parts of the prosthesis were Au-plated, but a later test showed that she was still allergic to Cr and also to Co."
1237673,Oleffe et al. 1972,European battery of skin tests: Results of 300 observations,"HEEP COPYRIGHT: BIOL ABS. The patch tests, recommended by the ""international Contact Dermatitis Research Group"" (ICDRG), included the 20 substances that most often give positive reactions in 8 European countries. The European standard set was used on patients suspected of having occupational contact dermatitis. Some differences from the results of the ICDRG study were noted, especially a greater frequency of positive tests to metals for females, a higher percentage of positive reactions to p-phenylenediamine (PPD), a more precocious sensitization to metals, and a lower frequency of reactions to medicaments because of selection of patients. In addition to well known allergens such as metals and p-phenylenediamine, rubber vulcanization accelerators and antioxidants are becoming more important. Wood tars are not common allergens. The European set took the place of the former battery used at the University of Brussels and introduced rubber vulcanization accelerators and some topical medicaments. It standardizes techniques of patch tests and permits, in spite of the small number of patients, comparing the results with those of other clinics.","European battery of skin tests: Results of 300 observations Abs: HEEP COPYRIGHT: BIOL ABS. The patch tests, recommended by the ""international Contact Dermatitis Research Group"" (ICDRG), included the 20 substances that most often give positive reactions in 8 European countries. The European standard set was used on patients suspected of having occupational contact dermatitis. Some differences from the results of the ICDRG study were noted, especially a greater frequency of positive tests to metals for females, a higher percentage of positive reactions to p-phenylenediamine (PPD), a more precocious sensitization to metals, and a lower frequency of reactions to medicaments because of selection of patients. In addition to well known allergens such as metals and p-phenylenediamine, rubber vulcanization accelerators and antioxidants are becoming more important. Wood tars are not common allergens. The European set took the place of the former battery used at the University of Brussels and introduced rubber vulcanization accelerators and some topical medicaments. It standardizes techniques of patch tests and permits, in spite of the small number of patients, comparing the results with those of other clinics."
1237670,Robustelli DELLA CUNA et al. 1972,Transformation into acute leukemia of a case of involutive myelopathy due to benzene poisoning,"HEEP COPYRIGHT: BIOL ABS. This case was followed up for 3 yr. Morphological, radioisotopic and cytogenetic studies were carried out. Since no bone marrow aspirate could be recovered by biopsy in repeated attempts for study, a satisfactory evaluation of the erythropoietic function and the kinetics of the Fe pools were obtained by means of radioactively labelled ferrous citrate and sodium chromate. The erythrokinetic study showed a low-rate incorporation into bone marrow and a high splenic uptake of the Fe-59. Cytogenetic investigation of the cultured peripheral lymphocytes with phytohemagglutinin stimulation showed a high rate of both stable and unstable chromosome alterations at the onset of the hemopathy. In the following years cells with more dispersed karyotypes disappeared. In the blastic stage, when myeloblasts appeared in the peripheral blood, 3 well-defined cell lines were observed: euploid, hypoploid (44 chromosomes) and hyperdiploid (47 chromosomes). Aneuploid karyotypes were defined by an extra chromosome of the 16-18 group and by deletion of a chromosome of the 17th pair. The hypothesis is suggested that a selective advantage of an abnormal clone (with chromosome alterations induced by benzene) might be responsible for the leukemic transformation in this case.","Transformation into acute leukemia of a case of involutive myelopathy due to benzene poisoning Abs: HEEP COPYRIGHT: BIOL ABS. This case was followed up for 3 yr. Morphological, radioisotopic and cytogenetic studies were carried out. Since no bone marrow aspirate could be recovered by biopsy in repeated attempts for study, a satisfactory evaluation of the erythropoietic function and the kinetics of the Fe pools were obtained by means of radioactively labelled ferrous citrate and sodium chromate. The erythrokinetic study showed a low-rate incorporation into bone marrow and a high splenic uptake of the Fe-59. Cytogenetic investigation of the cultured peripheral lymphocytes with phytohemagglutinin stimulation showed a high rate of both stable and unstable chromosome alterations at the onset of the hemopathy. In the following years cells with more dispersed karyotypes disappeared. In the blastic stage, when myeloblasts appeared in the peripheral blood, 3 well-defined cell lines were observed: euploid, hypoploid (44 chromosomes) and hyperdiploid (47 chromosomes). Aneuploid karyotypes were defined by an extra chromosome of the 16-18 group and by deletion of a chromosome of the 17th pair. The hypothesis is suggested that a selective advantage of an abnormal clone (with chromosome alterations induced by benzene) might be responsible for the leukemic transformation in this case."
1237669,Thulin and  Zachariae 1972,The leucocyte migration test in chromium hypersensitivity,"HEEP COPYRIGHT: BIOL ABS. Nine patients with patch tests positive for potassium bichromate were investigated by the leukocyte migration test. Specific inhibition of migration of leukocytes from patients with allergy to Cr was obtained with 3 different antigens: complexes of hexavalent Cr and bovine albumin, trivalent Cr and bovine albumin and hexavalent Cr and human dermal proteins. The highest degree of inhibition was seen with hexavalent Cr-bovine albumin. This indicates that the specificity of the carrier protein apparently is of lesser importance than earlier assumed. It is of interest to notice that both hexavalent and trivalent Cr may be used in the antigen complexes, probably due to reduction of hexavalent to Cr+3 prior to binding. No specific inhibition of migration was found in patients with contact allergy to compounds other than Cr.","The leucocyte migration test in chromium hypersensitivity Abs: HEEP COPYRIGHT: BIOL ABS. Nine patients with patch tests positive for potassium bichromate were investigated by the leukocyte migration test. Specific inhibition of migration of leukocytes from patients with allergy to Cr was obtained with 3 different antigens: complexes of hexavalent Cr and bovine albumin, trivalent Cr and bovine albumin and hexavalent Cr and human dermal proteins. The highest degree of inhibition was seen with hexavalent Cr-bovine albumin. This indicates that the specificity of the carrier protein apparently is of lesser importance than earlier assumed. It is of interest to notice that both hexavalent and trivalent Cr may be used in the antigen complexes, probably due to reduction of hexavalent to Cr+3 prior to binding. No specific inhibition of migration was found in patients with contact allergy to compounds other than Cr."
1237667,Valer and  Racz 1972,Investigations concerning the senzitizing effect of trivalent chromium salts. II. Studies using intracutaneous trivalent chromium salt tests,"HEEP COPYRIGHT: BIOL ABS. Intracutaneous tests were performed on 199 patients suffering from contact eczema due to handling Cr-containing materials at work (including 164 bichromate-positive individuals) and 50 control patients suffering from various occupational dermatological diseases not due to handling Cr. The investigations did not substantiate the primary allergen role of Cr (III) in giving positive bichromate reactions. Instead, these were apparently pseudo-specific or irritant ones. Independent Cr (III) sensitization appears to be a very rare occurrence.","Investigations concerning the senzitizing effect of trivalent chromium salts. II. Studies using intracutaneous trivalent chromium salt tests Abs: HEEP COPYRIGHT: BIOL ABS. Intracutaneous tests were performed on 199 patients suffering from contact eczema due to handling Cr-containing materials at work (including 164 bichromate-positive individuals) and 50 control patients suffering from various occupational dermatological diseases not due to handling Cr. The investigations did not substantiate the primary allergen role of Cr (III) in giving positive bichromate reactions. Instead, these were apparently pseudo-specific or irritant ones. Independent Cr (III) sensitization appears to be a very rare occurrence."
1237666,Kryuchkov and  Mareeva 1972,(Studies on measurements of oxidation capability of reclaimed water.),"HEEP COPYRIGHT: BIOL ABS. The significance of the data describing oxidation capability of reclaimed water obtained by different techniques for measuring oxidation capability of surface, ground and sewage waters was estimated. The kinetics of oxidation capability of admixtures occuring in the water condensate resulting from urine distillation by potassium dichromate was studied. The relationship between dichromate oxidation capability activity and reaction medium acidity as well as other factors was investigated. Various method of assaying oxidation capability may be employed for analysis of reclaimed water.","(Studies on measurements of oxidation capability of reclaimed water.) Abs: HEEP COPYRIGHT: BIOL ABS. The significance of the data describing oxidation capability of reclaimed water obtained by different techniques for measuring oxidation capability of surface, ground and sewage waters was estimated. The kinetics of oxidation capability of admixtures occuring in the water condensate resulting from urine distillation by potassium dichromate was studied. The relationship between dichromate oxidation capability activity and reaction medium acidity as well as other factors was investigated. Various method of assaying oxidation capability may be employed for analysis of reclaimed water."
1237664,Novak 1972,Experiments with a model of iontophoretic contact allergic reaction,"HEEP COPYRIGHT: BIOL ABS. In 40 latrogenically or professionally sensitized patients with eczema of different etiology iontophoretic tests with neomycin sulfate, potassium bichromate, nickel sulfate and acrinolin lactate (Rivanol) were made. The allergen was applied at 2 symmetrical sites simultaneously (13 patients); in 75 percent of the tested subjects the reactions on the 3rd and 4th day were approximately equal. In preventive and therapeutic application of Ultralan and Kenacort-A (11 patients), the order of effectiveness was: Ultralan, Kenacort-A, control. With intradermal administration of Methotrexate (4 patients), in one quarter a partial inhibition of the iontophoretic response was observed. Extraction of ions of the allergen from iontophoretic focus and intradermal test (11 patients) produced an intensification rather than weakening of the reactions. With block of iontophoresis by organic dyes (basic fuchsin and methylene blue) or Acutol spray, i.e. a plastic film in 9 patients, in 3/6 of the tested subjects the manifestations of the iontophoretic reactions at the site of injection of organic dyes were weaker and in 3/3 of the tested subjects there was total inhibition of the allergic reaction after Acutol spray. The model of iontophoretic contact allergy reaction can be recommended for investigations of the mechanism of contact allergic reactions and for tests of the antieczematous action of some externally applied drugs. The advantage of iontophoresis is active administration of the allergen, influencing and investigation of the developing reaction from the beginning.","Experiments with a model of iontophoretic contact allergic reaction Abs: HEEP COPYRIGHT: BIOL ABS. In 40 latrogenically or professionally sensitized patients with eczema of different etiology iontophoretic tests with neomycin sulfate, potassium bichromate, nickel sulfate and acrinolin lactate (Rivanol) were made. The allergen was applied at 2 symmetrical sites simultaneously (13 patients); in 75 percent of the tested subjects the reactions on the 3rd and 4th day were approximately equal. In preventive and therapeutic application of Ultralan and Kenacort-A (11 patients), the order of effectiveness was: Ultralan, Kenacort-A, control. With intradermal administration of Methotrexate (4 patients), in one quarter a partial inhibition of the iontophoretic response was observed. Extraction of ions of the allergen from iontophoretic focus and intradermal test (11 patients) produced an intensification rather than weakening of the reactions. With block of iontophoresis by organic dyes (basic fuchsin and methylene blue) or Acutol spray, i.e. a plastic film in 9 patients, in 3/6 of the tested subjects the manifestations of the iontophoretic reactions at the site of injection of organic dyes were weaker and in 3/3 of the tested subjects there was total inhibition of the allergic reaction after Acutol spray. The model of iontophoretic contact allergy reaction can be recommended for investigations of the mechanism of contact allergic reactions and for tests of the antieczematous action of some externally applied drugs. The advantage of iontophoresis is active administration of the allergen, influencing and investigation of the developing reaction from the beginning."
1237663,Kryshtab 1971,(Comparative evaluation of toxic effect produced by chromium dust and its high-melting compounds.),"HEEP COPYRIGHT: BIOL ABS. The effect of metallic Cr, chromium carbide, chromium boride and chromium oxide was studied on rats during intratracheal administration and inhalation. The substances had a weakly pronounced pneumoconiotic effect, the most dangerous being chromium oxide. Toxic effects increased from metallic chromium to chromium carbide to chromium boride. Chromium oxide dust was the most toxic. The substances were less toxic than chromium anhydride. On the basis of biochemical, immunological and pathomorphological changes, the maximum permissible concentrations were set at 0.5 mg/m-3 for chromium oxide, 1 mg/m-3 for chromium boride, 2 mg/m-3 for metallic Cr and 2 mg/m-3 for chromium carbide.","(Comparative evaluation of toxic effect produced by chromium dust and its high-melting compounds.) Abs: HEEP COPYRIGHT: BIOL ABS. The effect of metallic Cr, chromium carbide, chromium boride and chromium oxide was studied on rats during intratracheal administration and inhalation. The substances had a weakly pronounced pneumoconiotic effect, the most dangerous being chromium oxide. Toxic effects increased from metallic chromium to chromium carbide to chromium boride. Chromium oxide dust was the most toxic. The substances were less toxic than chromium anhydride. On the basis of biochemical, immunological and pathomorphological changes, the maximum permissible concentrations were set at 0.5 mg/m-3 for chromium oxide, 1 mg/m-3 for chromium boride, 2 mg/m-3 for metallic Cr and 2 mg/m-3 for chromium carbide."
1237662,Kabe 1971,[Bronchial asthma and asthma-like dyspnea caused by inhalation of simple chemicals],"Usually allergic asthma is thought to be an anaphylactic type of reaction in the lungs but recently a different pattern of bronchopulmonary hypersensitivity was described in which pulmonary infiltrations occur in association with precipitating antibodies and a positive Arthus type skin reaction. A delayed type allergic reaction of the skin and the lungs in guinea pigs as well as in man occurring after injection or inhalation of extracts of Candida albicans was previously reported. In this paper reports of bronchial asthma and asthma-like dyspnea caused by occupational exposure to simple chemicals were reviewed and these reactions could be divided into 4 types according to the allergologic patterns observed: immediate type, delayed type, non-allergic, irritative type, and undetermined type reactions to these substances. Inhalation test, skin test, and determination of circulating antibodies in each group were summarized. To clarify the mechanism of dyspnea, immediate and late respiratory reactions in guinea pigs were recorded by oscillation method after frequent inhalation of simple chemicals such as potassium dichromate, formalin and/or paraphenylene diamine. However, no evidence of specific immunologic reactions was found. Possible explanations for these results were discussed.","[Bronchial asthma and asthma-like dyspnea caused by inhalation of simple chemicals] Abs: Usually allergic asthma is thought to be an anaphylactic type of reaction in the lungs but recently a different pattern of bronchopulmonary hypersensitivity was described in which pulmonary infiltrations occur in association with precipitating antibodies and a positive Arthus type skin reaction. A delayed type allergic reaction of the skin and the lungs in guinea pigs as well as in man occurring after injection or inhalation of extracts of Candida albicans was previously reported. In this paper reports of bronchial asthma and asthma-like dyspnea caused by occupational exposure to simple chemicals were reviewed and these reactions could be divided into 4 types according to the allergologic patterns observed: immediate type, delayed type, non-allergic, irritative type, and undetermined type reactions to these substances. Inhalation test, skin test, and determination of circulating antibodies in each group were summarized. To clarify the mechanism of dyspnea, immediate and late respiratory reactions in guinea pigs were recorded by oscillation method after frequent inhalation of simple chemicals such as potassium dichromate, formalin and/or paraphenylene diamine. However, no evidence of specific immunologic reactions was found. Possible explanations for these results were discussed."
1237661,Miyazaki 1971,Application of thin layer chromatography to forensic toxicology: Thin layer chromatography of metallic poisons,"HEEP COPYRIGHT: BIOL ABS. Compounds (25) from 11 types of metals relevent to forensic toxicology were qualitatively assayed using thin layer chromatography. Specific details and methodology were given. Subsequently, these metallic poisons were identified in the bodies of rabbits, following their death which was due to administration of these poisonous substances. The metallic poisons used were arsenic oxide, barium nitrate, cadmium chloride, mercuric chloride, and lead nitrate, each administered separately to the rabbits until they died. Using a specific thin layer chromatography technique which was developed. Each of these metallic poisons were distinctly identified from the stomach contents and liver of these animals.","Application of thin layer chromatography to forensic toxicology: Thin layer chromatography of metallic poisons Abs: HEEP COPYRIGHT: BIOL ABS. Compounds (25) from 11 types of metals relevent to forensic toxicology were qualitatively assayed using thin layer chromatography. Specific details and methodology were given. Subsequently, these metallic poisons were identified in the bodies of rabbits, following their death which was due to administration of these poisonous substances. The metallic poisons used were arsenic oxide, barium nitrate, cadmium chloride, mercuric chloride, and lead nitrate, each administered separately to the rabbits until they died. Using a specific thin layer chromatography technique which was developed. Each of these metallic poisons were distinctly identified from the stomach contents and liver of these animals."
1237658,Robin and  Aron-Brunetiere 1971,OCCUPATIONAL DERMATOSIS OF 1ST IMPORTANCE CEMENT DERMATITIS,HEEP COPYRIGHT: BIOL ABS. HUMAN CHROMIUM POTASSIUM BI CHROMATE DIAGNOSIS ALLERGY,OCCUPATIONAL DERMATOSIS OF 1ST IMPORTANCE CEMENT DERMATITIS Abs: HEEP COPYRIGHT: BIOL ABS. HUMAN CHROMIUM POTASSIUM BI CHROMATE DIAGNOSIS ALLERGY
1237656,Burckhardt et al. 1971,(Decrease of the eczematous effect of cement by ferrous sulfate.),HEEP COPYRIGHT: BIOL ABS. Ferrous sulfate combines with potassium dichromate in cement to form an isoluble compound. The addition of 0.3 percent ferrous sulfate to patch tests with cement reduced in sensitive individuals the intensity of patch test reactions and abolished it in some altogether. Patients with a normal skin alkaline resistance test benefited most. These observations suggest possible prevention of cement-induced chromate sensitivity.,(Decrease of the eczematous effect of cement by ferrous sulfate.) Abs: HEEP COPYRIGHT: BIOL ABS. Ferrous sulfate combines with potassium dichromate in cement to form an isoluble compound. The addition of 0.3 percent ferrous sulfate to patch tests with cement reduced in sensitive individuals the intensity of patch test reactions and abolished it in some altogether. Patients with a normal skin alkaline resistance test benefited most. These observations suggest possible prevention of cement-induced chromate sensitivity.
1237655,Kryshtab 1971,(Pneumoconiotic and general toxic effect of chromium dust and infusible chromium compounds.),"HEEP COPYRIGHT: BIOL ABS. Experiments on animals indicate that chromium biride dust has a marked fibrogenous effect. Mettalic Cr dust is less fibrogenic. The least fibrogenous effect is exerted by the dusts of chromium carbide and chromium oxide. Resistance of the organism is sharply reduced under the effect of chromium oxide dust, but only insignificantly under the effect of the dust of metallic Cr, chromium carbide, and chromium boride. Morphological changes in parenchymatous organs reveal disorders of the protein metabolism. These changes correlate well with biochemical data. The general toxic effect of these substances is less distinct than the pneumoconiotic effect.","(Pneumoconiotic and general toxic effect of chromium dust and infusible chromium compounds.) Abs: HEEP COPYRIGHT: BIOL ABS. Experiments on animals indicate that chromium biride dust has a marked fibrogenous effect. Mettalic Cr dust is less fibrogenic. The least fibrogenous effect is exerted by the dusts of chromium carbide and chromium oxide. Resistance of the organism is sharply reduced under the effect of chromium oxide dust, but only insignificantly under the effect of the dust of metallic Cr, chromium carbide, and chromium boride. Morphological changes in parenchymatous organs reveal disorders of the protein metabolism. These changes correlate well with biochemical data. The general toxic effect of these substances is less distinct than the pneumoconiotic effect."
1237651,Tsyrkunov 1970,Modern methods for diagnosing occupational diseases of the skin in workers in the chemical industry,"HEEP COPYRIGHT: BIOL ABS. When diagnoses are being made of allergic occupational diseases of the skin, to determine the degree of increased sensitivity to chemicals use should be made of skin tests and the Shelley immunobiological reaction. Intradermal tests are indicated for substances which might be introduced parenterally. Compresses and application methods for skin tests may be used for substances soluble in organic solvents. Using the drop method of skin testing, not only must the suspected allergen be included but also the most widespread allergens-nickel chloride, turpentine, K2Cr2O7. Occupational allergic diseases of the skin usually develop after several months of work in contact with the chemicals (in 5-10 yr of contact with antibiotics); inflammatory reactions disappear soon after contact with the irritant stops.","Modern methods for diagnosing occupational diseases of the skin in workers in the chemical industry Abs: HEEP COPYRIGHT: BIOL ABS. When diagnoses are being made of allergic occupational diseases of the skin, to determine the degree of increased sensitivity to chemicals use should be made of skin tests and the Shelley immunobiological reaction. Intradermal tests are indicated for substances which might be introduced parenterally. Compresses and application methods for skin tests may be used for substances soluble in organic solvents. Using the drop method of skin testing, not only must the suspected allergen be included but also the most widespread allergens-nickel chloride, turpentine, K2Cr2O7. Occupational allergic diseases of the skin usually develop after several months of work in contact with the chemicals (in 5-10 yr of contact with antibiotics); inflammatory reactions disappear soon after contact with the irritant stops."
1237650,Tulegenov and  Chaikovskii 1970,Activity of the Kazakh Scientific Research Institute in support of public health bodies,"HEEP COPYRIGHT: BIOL ABS. The Institute is primarily concerned with studying working conditions and occupational pathology in the coal and ore mining industries, ferrous and non-ferrous metallurgy and chemical industries of central Kazakhstan and has helped public health organizations in various projects. These include studies in noise and vibration and occupational and allergic skin diseases, dermatoses and potassium bichromate and erysipelas in meat industries. The function of the clinical division of the institute in setting qualifications for doctors and conducting seminars is also mentioned. The Institute also examines and compiles data on construction and reorganization of industrial enterprises and introduces new equipment.","Activity of the Kazakh Scientific Research Institute in support of public health bodies Abs: HEEP COPYRIGHT: BIOL ABS. The Institute is primarily concerned with studying working conditions and occupational pathology in the coal and ore mining industries, ferrous and non-ferrous metallurgy and chemical industries of central Kazakhstan and has helped public health organizations in various projects. These include studies in noise and vibration and occupational and allergic skin diseases, dermatoses and potassium bichromate and erysipelas in meat industries. The function of the clinical division of the institute in setting qualifications for doctors and conducting seminars is also mentioned. The Institute also examines and compiles data on construction and reorganization of industrial enterprises and introduces new equipment."
1237648,Folesky and  Rothe 1970,Allergic eczema through epsilon-aminocaproic acid (EAC),HEEP COPYRIGHT: BIOL ABS. The antifibrinolytic effect and other pharmacologic properties of EAC were discussed. A case of allergic eczema induced by the external application of EAC and the unreliable therapeutic effect of this drug in 11 other eczema patients makes the applicability of EAC for the therapy of allergic diseases appear questionable.,Allergic eczema through epsilon-aminocaproic acid (EAC) Abs: HEEP COPYRIGHT: BIOL ABS. The antifibrinolytic effect and other pharmacologic properties of EAC were discussed. A case of allergic eczema induced by the external application of EAC and the unreliable therapeutic effect of this drug in 11 other eczema patients makes the applicability of EAC for the therapy of allergic diseases appear questionable.
1237647,Rudzki and  Kleniewska 1970,Set of contact allergens in Poland,"HEEP COPYRIGHT: BIOL ABS. Data concerning the composition of a set of contact allergens and a method of testing with them approved by the Polish Dermatological Society is reported. In addition, main occupational and extraoccupational sources of occurrence of the allergens are discussed.","Set of contact allergens in Poland Abs: HEEP COPYRIGHT: BIOL ABS. Data concerning the composition of a set of contact allergens and a method of testing with them approved by the Polish Dermatological Society is reported. In addition, main occupational and extraoccupational sources of occurrence of the allergens are discussed."
1237645,Da Fonseca 1969,(Method for determining skin reactivity to chromium.),"HEEP COPYRIGHT: BIOL ABS. There are considerable differences of opinion concerning the right concentration of potassium dichromate solutions for intradermal and epicutaneous tests used to determine sensitivity of the skin to chrome; they vary from 0.01% to 5% for epicutaneous and from 0.00001 to 0.1% for intracutaneous tests. The bases for the technique and interpretation of the reactions are presented. The results are called reactive, non-reactive and doubtful, and graded from 1 to 4 in accordance with the reactions. The object is to separate hypersensitivity from simple irritation. Results marked R1 and R2 are considered signs of hypersensitivity; those marked R3 and R4, signs of irritation. The norms are supplied which in practice should serve to ascertain whether a given product is capable of producing eczematoid cutaneous reactivity in a certain individual and, in a positive case, to learn the minimal effective concentration.","(Method for determining skin reactivity to chromium.) Abs: HEEP COPYRIGHT: BIOL ABS. There are considerable differences of opinion concerning the right concentration of potassium dichromate solutions for intradermal and epicutaneous tests used to determine sensitivity of the skin to chrome; they vary from 0.01% to 5% for epicutaneous and from 0.00001 to 0.1% for intracutaneous tests. The bases for the technique and interpretation of the reactions are presented. The results are called reactive, non-reactive and doubtful, and graded from 1 to 4 in accordance with the reactions. The object is to separate hypersensitivity from simple irritation. Results marked R1 and R2 are considered signs of hypersensitivity; those marked R3 and R4, signs of irritation. The norms are supplied which in practice should serve to ascertain whether a given product is capable of producing eczematoid cutaneous reactivity in a certain individual and, in a positive case, to learn the minimal effective concentration."
1237644,Spritzer et al. ,CLEARANCE RATES DETERMINANTS PARAMETERS INFLUENCING CLEARANCE RATES OF PARTICLES IN THE UPPER RESPIRATORY TRACT,HEEP COPYRIGHT: BIOL ABS. RAT LINEAR PARTICLE TRANSPORT VELOCITY LEAD CHROMATE,CLEARANCE RATES DETERMINANTS PARAMETERS INFLUENCING CLEARANCE RATES OF PARTICLES IN THE UPPER RESPIRATORY TRACT Abs: HEEP COPYRIGHT: BIOL ABS. RAT LINEAR PARTICLE TRANSPORT VELOCITY LEAD CHROMATE
1237643,Ludosan 1972,A method for the decontamination of the protective equipment used in pest control,"HAPAB Chemical procedures for the decontamination of protective equipment after exposure to organophosphates such as malathion or parathion are presented. Malathion can be removed by washing with water at room temperature or 45 DEG C and soaking in 0.2 to 0.5% sodium hydroxide solutions at room temperature for 24 hours. Rinsing with water (twice) provides satisfactory results with malathion residues below 2 gamma/cm(SUP)2, regardless of the handled malathion concentration. Parathion preparations containing 50% active matter can be removed by washing the equipment with a 2% sodium hydroxide and a 0.5% sodium or potassium bichromate solution after a first wash with water at 50 DEG C; the equipment is then boiled 1/2 hour with the sodium hydroxide and bichromate solution mixture and rinsed twice with clean water; parathion residues are reduced to below 5 DELTA/cm(SUP)2. Protective equipment can be decontaminated by 1/2 hr soaking in a 0.5% sodium bisulfite solution at room temperature after exposure to diluted (0.08-0.10%) parathion preparations. Rinsing with water provided decontamination of residues as low as 2 gamma/cm(SUP)2 parathion.","A method for the decontamination of the protective equipment used in pest control Abs: HAPAB Chemical procedures for the decontamination of protective equipment after exposure to organophosphates such as malathion or parathion are presented. Malathion can be removed by washing with water at room temperature or 45 DEG C and soaking in 0.2 to 0.5% sodium hydroxide solutions at room temperature for 24 hours. Rinsing with water (twice) provides satisfactory results with malathion residues below 2 gamma/cm(SUP)2, regardless of the handled malathion concentration. Parathion preparations containing 50% active matter can be removed by washing the equipment with a 2% sodium hydroxide and a 0.5% sodium or potassium bichromate solution after a first wash with water at 50 DEG C; the equipment is then boiled 1/2 hour with the sodium hydroxide and bichromate solution mixture and rinsed twice with clean water; parathion residues are reduced to below 5 DELTA/cm(SUP)2. Protective equipment can be decontaminated by 1/2 hr soaking in a 0.5% sodium bisulfite solution at room temperature after exposure to diluted (0.08-0.10%) parathion preparations. Rinsing with water provided decontamination of residues as low as 2 gamma/cm(SUP)2 parathion."
1237642,Chamberlain 1971,The determination of urinary 6-oxygenated cortisol in evaluating liver function,"HAPAB The measurement of urinary 6beta-hydroxycortisol can be used to monitor exposure to substances including pesticides which induce hepatic microsomal hydroxylating enzymes. Since 6beta-hydroxycortisol is not stable under normal gas chromatographic conditions, a stable derivative must be formed for analysis. In the present method, a crude urine extract was oxidized with chromium trioxide in sulfuric acid to form androst-4-ene-3,6,11,17-tetrone, which is stable during gas chromatography and has strong electron-capturing properties, thus permitting rapid analysis of small urine volumes. The mean 24-hour excretion value of 255 mug found in ten normal male laboratory workers was recalculated, based on the A-ring reduced metabolites in the same urine sample, as determined by the method of Metcalf, giving a mean value of 30.7 mug 6-oxysteroid per mg reduced steroid. Similar values were found for employees of a chemical company in Amsterdam who were not occupationally exposed to pesticides and workers exposed to aldrin and dieldrin; a third group exposed to endrin, however, had a mean value of 91.0 mug/mg. 1971","The determination of urinary 6-oxygenated cortisol in evaluating liver function Abs: HAPAB The measurement of urinary 6beta-hydroxycortisol can be used to monitor exposure to substances including pesticides which induce hepatic microsomal hydroxylating enzymes. Since 6beta-hydroxycortisol is not stable under normal gas chromatographic conditions, a stable derivative must be formed for analysis. In the present method, a crude urine extract was oxidized with chromium trioxide in sulfuric acid to form androst-4-ene-3,6,11,17-tetrone, which is stable during gas chromatography and has strong electron-capturing properties, thus permitting rapid analysis of small urine volumes. The mean 24-hour excretion value of 255 mug found in ten normal male laboratory workers was recalculated, based on the A-ring reduced metabolites in the same urine sample, as determined by the method of Metcalf, giving a mean value of 30.7 mug 6-oxysteroid per mg reduced steroid. Similar values were found for employees of a chemical company in Amsterdam who were not occupationally exposed to pesticides and workers exposed to aldrin and dieldrin; a third group exposed to endrin, however, had a mean value of 91.0 mug/mg. 1971"
1237640,Block 1969,The accident that saved five lives; a strange-but-true story of how a young doctor discovered that his family was being poisoned,"HAPAB The story is narrated of a doctor, his wife and four young children who were suffering the effects of lead accumulation from ingestion through an unsuspected source. The members of the family complained variously of fatigue, intermittent stomach pains and poor appetite. One young son developed self-sided paralysis and was rushed to the hospital for exploratory neurosurgery. Though a suspected brain hemorrhage was not found, the findings suggested the presence of a tumor. Blood tests for the child showed marked anemia and indications of severe nalnutrition; the latter finding was peculiar because the doctor knew hes family was receiving nutritious, well-balanced meals. The boy recovered good health and his symptoms vanished after blood transfusions. After returning home, his initial vigorous appetite declined and his earlier symptoms reappeared; the other children alwo were more and more apathetic to eating. Suspecting the children were ruining their appetites by drinking too much fruit juice before meals, the pitcher was removed for a few days. Appetites increased; but because fruit juices are important to child nutrition, the pitcher was used once again. Within weeks, the family's symptoms began again. This time blood tests on one daughter and the doctor himself indicated nearly lethal levels of lead poisoning. The plumbing was checked as a possible source of the lead; pica was ruled out since the parents as well as the children were being affected. Finally suspecting the family juice pitcher, it was analyzed and one washing with acid produced enough lead chromate to kill two people. The pitcher was a pottery one made in Mexico but insufficiently fired so that the glaze failed to seal completely. Juices such as orange juice in the pitcher caused leaching out of the lead which was the source of the family's poisoning. EPIDEMIOLOGY AND TREATMENT 70/01/00, 20 1969","The accident that saved five lives; a strange-but-true story of how a young doctor discovered that his family was being poisoned Abs: HAPAB The story is narrated of a doctor, his wife and four young children who were suffering the effects of lead accumulation from ingestion through an unsuspected source. The members of the family complained variously of fatigue, intermittent stomach pains and poor appetite. One young son developed self-sided paralysis and was rushed to the hospital for exploratory neurosurgery. Though a suspected brain hemorrhage was not found, the findings suggested the presence of a tumor. Blood tests for the child showed marked anemia and indications of severe nalnutrition; the latter finding was peculiar because the doctor knew hes family was receiving nutritious, well-balanced meals. The boy recovered good health and his symptoms vanished after blood transfusions. After returning home, his initial vigorous appetite declined and his earlier symptoms reappeared; the other children alwo were more and more apathetic to eating. Suspecting the children were ruining their appetites by drinking too much fruit juice before meals, the pitcher was removed for a few days. Appetites increased; but because fruit juices are important to child nutrition, the pitcher was used once again. Within weeks, the family's symptoms began again. This time blood tests on one daughter and the doctor himself indicated nearly lethal levels of lead poisoning. The plumbing was checked as a possible source of the lead; pica was ruled out since the parents as well as the children were being affected. Finally suspecting the family juice pitcher, it was analyzed and one washing with acid produced enough lead chromate to kill two people. The pitcher was a pottery one made in Mexico but insufficiently fired so that the glaze failed to seal completely. Juices such as orange juice in the pitcher caused leaching out of the lead which was the source of the family's poisoning. EPIDEMIOLOGY AND TREATMENT 70/01/00, 20 1969"
1237639,Power et al. 1969,Lead poisoning in Gurhka soldiers in Hong Kong,"HAPAB In March to June 1968, 75 Gurkha soldiers presented themselves with symptoms of epigastric pain, nausea, constipation and tenderness of the recti abdominis and other muscles. The discovery upon hospitalization of anemia and basophilic stippling of red cells suggested heavy metal poisoning. Of the 75 patients with symptoms, 63 complained of constant epigastric pain, but only 20 had classical =lead colic.= Clinical findings in patients included: blue lines on the gums in about 19% and an unexpected bilateral limitation of lateral gaze in 60%. Hemoglobin levels of less than 11.4 g/100 ml of blood were shown in 110 of the 121 patients and basophilic stippling of red cells was seen in 51% of the cases. Urinary coproporphyrin levels exceeding 200 mcg/l were found in 86% and urinary excretion rates investigated in 58 patients showed an average figure of 455 mcg in 24 hr. Closing of the cookhouse resulted in a significant decrease of new cases. Investigations disclosed that = ghee= ( clarified butterfat ) used in cooking was contaminated with lead. Reopening the cookhouse after removal of the contaminated ghee caused the appearance of new cases indicating that lead poisoning was still occurring. Further investigations disclosed that samples of ghee which had been reused several times in the cooking process contained 50 ppm of lead while unused ghee had a lead content of 0.6 ppm. However, chilli powder, a component of curry powder, with which the meat was spiced before frying contained 10,800 ppm of lead. It is believed that deliberate adulteration of the chilli powder with lead chromate was practiced to improve the color or to increase the weight of the chilli powder. Closer supervision of food processing establishments and food sampling is recommended, particularly, in developing countries. EPIDEMIOLOGY AND TREATMENT 69/12/00, 439 1969","Lead poisoning in Gurhka soldiers in Hong Kong Abs: HAPAB In March to June 1968, 75 Gurkha soldiers presented themselves with symptoms of epigastric pain, nausea, constipation and tenderness of the recti abdominis and other muscles. The discovery upon hospitalization of anemia and basophilic stippling of red cells suggested heavy metal poisoning. Of the 75 patients with symptoms, 63 complained of constant epigastric pain, but only 20 had classical =lead colic.= Clinical findings in patients included: blue lines on the gums in about 19% and an unexpected bilateral limitation of lateral gaze in 60%. Hemoglobin levels of less than 11.4 g/100 ml of blood were shown in 110 of the 121 patients and basophilic stippling of red cells was seen in 51% of the cases. Urinary coproporphyrin levels exceeding 200 mcg/l were found in 86% and urinary excretion rates investigated in 58 patients showed an average figure of 455 mcg in 24 hr. Closing of the cookhouse resulted in a significant decrease of new cases. Investigations disclosed that = ghee= ( clarified butterfat ) used in cooking was contaminated with lead. Reopening the cookhouse after removal of the contaminated ghee caused the appearance of new cases indicating that lead poisoning was still occurring. Further investigations disclosed that samples of ghee which had been reused several times in the cooking process contained 50 ppm of lead while unused ghee had a lead content of 0.6 ppm. However, chilli powder, a component of curry powder, with which the meat was spiced before frying contained 10,800 ppm of lead. It is believed that deliberate adulteration of the chilli powder with lead chromate was practiced to improve the color or to increase the weight of the chilli powder. Closer supervision of food processing establishments and food sampling is recommended, particularly, in developing countries. EPIDEMIOLOGY AND TREATMENT 69/12/00, 439 1969"
1237638,Kothny 1969,"Trace determination of mercury, thallium and gold with crystal violet","HAPAB A spectrophotometric method for the determination of small amounts of mercury, thallium and gold is presented. The sample is digested with nitric acid, containing chromium trioxide, treated with potassium permanganate and hydrogen peroxide and then receives hydrochloric acid. An alternative rapid wet-ashing method is to treat the sample with fuming nitric acid, hydrogen peroxide and chromium-iron solution. Inorganic samples are ground and digested with an acid mixture. Interferences are eliminated by adding ethylene glycol monomethyl ether and EDTA ( ethylenediaminetetra acid ). Thallium interference is eliminated by adding sodium metabisulfite for mercury and gold, whereas excess oxidant interference is eliminated by adding hydroxylamine for thallium and gold. Because gold interferes in the determination of thallium and mercury, it is determined separately after heating the sample to volatilize the mercury, Iodine forms complexes with mercury and gold, whereas bromide forms complexes with thallium and gold. Crystal violet produces an toluene-extractable compound with these complexes in an acidic medium. A single extraction step is necessary to determine 0.1 mcg of each element in a 1-cm cell with a standard spectrophotometer at 605 nm; Beer's law is followed up to absorbance of unity. The method was tested with wine, air, vegetation, water, soils, rocks and sediments. ANALYSIS 69/08/00, 274 1969","Trace determination of mercury, thallium and gold with crystal violet Abs: HAPAB A spectrophotometric method for the determination of small amounts of mercury, thallium and gold is presented. The sample is digested with nitric acid, containing chromium trioxide, treated with potassium permanganate and hydrogen peroxide and then receives hydrochloric acid. An alternative rapid wet-ashing method is to treat the sample with fuming nitric acid, hydrogen peroxide and chromium-iron solution. Inorganic samples are ground and digested with an acid mixture. Interferences are eliminated by adding ethylene glycol monomethyl ether and EDTA ( ethylenediaminetetra acid ). Thallium interference is eliminated by adding sodium metabisulfite for mercury and gold, whereas excess oxidant interference is eliminated by adding hydroxylamine for thallium and gold. Because gold interferes in the determination of thallium and mercury, it is determined separately after heating the sample to volatilize the mercury, Iodine forms complexes with mercury and gold, whereas bromide forms complexes with thallium and gold. Crystal violet produces an toluene-extractable compound with these complexes in an acidic medium. A single extraction step is necessary to determine 0.1 mcg of each element in a 1-cm cell with a standard spectrophotometer at 605 nm; Beer's law is followed up to absorbance of unity. The method was tested with wine, air, vegetation, water, soils, rocks and sediments. ANALYSIS 69/08/00, 274 1969"
1237637,Tanaka and  Ikeda 1968,A method for determination of trichloroethanol and trichloroacetic acid in urine,"HAPAB An improvement in the Seto and Schultze's method for the determination of trichloroacetic acid ( TCA ) and trichloroethanol ( TCE ) in the urine of human subjects, rabbits, rats and guinea pigs is described. By using more drastic oxidation conditions satisfactory recoveries ( more than 95% ) were obtained. Best results were obtained with a 0.5 ml portion of a mixture of 8 g chromium trioxide, 5 ml water, and 15 ml concentrated nitric acid as oxidant at a digestion temperature of 65 degrees C for 4 hr. The modified method was used to estimate the TCA and TCE in the urine of human subjects and of rats exposed to trichloroethylene. The results showed that the ratio of TCE to TCA varies as a function of environmental trichloroethylene concentration, indicating that the determination of total trichloro- compounds gives a better index of trichloroethylene exposure than does the determination of TCA alone. ANALYSIS 68/11/00, 28 1968","A method for determination of trichloroethanol and trichloroacetic acid in urine Abs: HAPAB An improvement in the Seto and Schultze's method for the determination of trichloroacetic acid ( TCA ) and trichloroethanol ( TCE ) in the urine of human subjects, rabbits, rats and guinea pigs is described. By using more drastic oxidation conditions satisfactory recoveries ( more than 95% ) were obtained. Best results were obtained with a 0.5 ml portion of a mixture of 8 g chromium trioxide, 5 ml water, and 15 ml concentrated nitric acid as oxidant at a digestion temperature of 65 degrees C for 4 hr. The modified method was used to estimate the TCA and TCE in the urine of human subjects and of rats exposed to trichloroethylene. The results showed that the ratio of TCE to TCA varies as a function of environmental trichloroethylene concentration, indicating that the determination of total trichloro- compounds gives a better index of trichloroethylene exposure than does the determination of TCA alone. ANALYSIS 68/11/00, 28 1968"
1237636,Livshits ,The prophylactic role of local pectin - containing food products in lead intoxications,"HAPAB The preventive role of pectin - containing foods in lead poisonings was investigated. Three groups of male white rats were used. The first group was the control and received the usual ration of a greens mixture, bread, milk, meat and other products for a total kilocalorie value of 52. The second group received 50% by weights of the above, usual ration as well as 25% white cabbage and 25% carrots. The third group was maintained on the same ration as group 2 but only for 1 week before the lead dosage. The overall pectin content of the diet for the experimental groups was 0.5% by weight of the ration. Lead acetate was given perorally daily for 1 month, 50 mg/kg of body weight. Urinary and fecal lead excretion was determined by wet ashing and subsequent nephelometric determination of lead chromate. The fluorescence method was also employed to study urinary coproporphyrin III. Enriching the usual die with carrots and cabbage containing pectic substances intensified the excretion of lead 38 to 44% and had a favorable effect on the aniaml's state of health by decreasing lead intoxication. The best results were obtaining ggroup 3 which received the pectic - enriched diet for 1 week prior to the lead administration. Controls showed th effects of lead - induced metabolic disorder by a 10 - to 15 - fold increase in urinary excretion of coproporphyrin III which was not noted in the experimental rats. EPIDEMIOLOGY AND TREATMENT 70/05/00, 188","The prophylactic role of local pectin - containing food products in lead intoxications Abs: HAPAB The preventive role of pectin - containing foods in lead poisonings was investigated. Three groups of male white rats were used. The first group was the control and received the usual ration of a greens mixture, bread, milk, meat and other products for a total kilocalorie value of 52. The second group received 50% by weights of the above, usual ration as well as 25% white cabbage and 25% carrots. The third group was maintained on the same ration as group 2 but only for 1 week before the lead dosage. The overall pectin content of the diet for the experimental groups was 0.5% by weight of the ration. Lead acetate was given perorally daily for 1 month, 50 mg/kg of body weight. Urinary and fecal lead excretion was determined by wet ashing and subsequent nephelometric determination of lead chromate. The fluorescence method was also employed to study urinary coproporphyrin III. Enriching the usual die with carrots and cabbage containing pectic substances intensified the excretion of lead 38 to 44% and had a favorable effect on the aniaml's state of health by decreasing lead intoxication. The best results were obtaining ggroup 3 which received the pectic - enriched diet for 1 week prior to the lead administration. Controls showed th effects of lead - induced metabolic disorder by a 10 - to 15 - fold increase in urinary excretion of coproporphyrin III which was not noted in the experimental rats. EPIDEMIOLOGY AND TREATMENT 70/05/00, 188"
1237635,Marlett et al. 1986,DETERMINING COMPLIANCE WITH A DIETARY FIBER SUPPLEMENT,"EIS: Epidemiology Information System THE PURPOSE OF THIS PILOT STUDY WAS TO EVALUATE POSSIBLE WAYS TO DETERMINE COMPLIANCE WITH A DIETARY FIBER SUPPLEMENT. A WHEAT BRAN SUPPLEMENT (30 G DAILY) SIGNIFICANTLY INCREASED MEAN DAILY WET AND DRY STOOL WEIGHTS (SW) IN 7 ADULTS, WHEN COMPARED TO SW DURING AN AD LIBITUM LOW-FIBER DIET (PAIRED T-TEST, P LESS THAN .01). BECAUSE UNPAIRED DATA WOULD BE USED DURING A CLINICAL TRIAL, DISTRIBUTION OF THE 7 AD LIBITUM LOW-FIBER MEAN SW OBSERVATIONS WAS USED TO ESTABLISH A REFERENCE DISTRIBUTION AND AN UPPER CONFIDENCE LIMIT AGAINST WHICH THE BRAN SUPPLEMENT SW COULD BE COMPARED. ONLY ONE OF THE SEVEN BRAN SUPPLEMENT MEAN SW WAS ABOVE THE CONFIDENCE LIMIT OF THE LOW-FIBER PERIOD, INDEPENDENT OF THE NUMBER OF DAYS OF COLLECTION (2-10) USED TO CALCULATE THE INDIVIDUAL MEAN DAILY SW. TOTAL FECAL OUTPUT OVER VARYING PERIODS OF TIME (2-10 DAYS) SUFFERED THE SAME INTERSUBJECT AND INTRASUBJECT VARIABILITY. MOST (5-6) OF THE BRAN MEAN DAILY SW WERE ABOVE THE GROUP MEAN SW OF THE LOW-FIBER PERIOD. HOWEVER, THIS DOSE OF BRAN WAS LARGE ENOUGH TO SIGNIFICANTLY DECREASE CALCIUM ABSORPTION, AND DIFFERENCES IN SW PRODUCED BY LOWER DOSES OF WHEAT BRAN WOULD PROBABLY NOT BE AS GREAT. THE BULK (GREATER THAN OR EQUAL TO 80%) OF A SINGLE DOSE OF A FECAL MARKER, CHROMIUM SESQUIOXIDE, WHICH COULD BE INCORPORATED INTO A SPECIFIC DAY'S FIBER SUPPLEMENT, WAS RECOVERED IN 5 DAYS OF EXCRETION DURING THE CONTROL PERIOD AND IN 4 DAYS DURING THE BRAN PERIOD. HOWEVER, THE BLUE COLOR OF THE CHROMIUM BEFORE INGESTION IS CLEARLY A NEGATIVE FEATURE. ANOTHER MARKER, POLYETHYLENE GLYCOL, COULD NOT BE RECOVERED IN EXCRETA WHEN TRANSIENT TIME WAS 4 DAYS OR MORE. IN A SEPARATE STUDY, DEMONSTRATION OF VERY LITTLE OVERLAP IN THE CONCENTRATION OF FECAL NEUTRAL DETERGENT FIBER BETWEEN THE CONTROL AND BRAN PERIODS SUGGESTS THAT FECAL FIBER MAY BE A MARKER OF COMPLIANCE WITH A FIBER SUPPLEMENT.","DETERMINING COMPLIANCE WITH A DIETARY FIBER SUPPLEMENT Abs: EIS: Epidemiology Information System THE PURPOSE OF THIS PILOT STUDY WAS TO EVALUATE POSSIBLE WAYS TO DETERMINE COMPLIANCE WITH A DIETARY FIBER SUPPLEMENT. A WHEAT BRAN SUPPLEMENT (30 G DAILY) SIGNIFICANTLY INCREASED MEAN DAILY WET AND DRY STOOL WEIGHTS (SW) IN 7 ADULTS, WHEN COMPARED TO SW DURING AN AD LIBITUM LOW-FIBER DIET (PAIRED T-TEST, P LESS THAN .01). BECAUSE UNPAIRED DATA WOULD BE USED DURING A CLINICAL TRIAL, DISTRIBUTION OF THE 7 AD LIBITUM LOW-FIBER MEAN SW OBSERVATIONS WAS USED TO ESTABLISH A REFERENCE DISTRIBUTION AND AN UPPER CONFIDENCE LIMIT AGAINST WHICH THE BRAN SUPPLEMENT SW COULD BE COMPARED. ONLY ONE OF THE SEVEN BRAN SUPPLEMENT MEAN SW WAS ABOVE THE CONFIDENCE LIMIT OF THE LOW-FIBER PERIOD, INDEPENDENT OF THE NUMBER OF DAYS OF COLLECTION (2-10) USED TO CALCULATE THE INDIVIDUAL MEAN DAILY SW. TOTAL FECAL OUTPUT OVER VARYING PERIODS OF TIME (2-10 DAYS) SUFFERED THE SAME INTERSUBJECT AND INTRASUBJECT VARIABILITY. MOST (5-6) OF THE BRAN MEAN DAILY SW WERE ABOVE THE GROUP MEAN SW OF THE LOW-FIBER PERIOD. HOWEVER, THIS DOSE OF BRAN WAS LARGE ENOUGH TO SIGNIFICANTLY DECREASE CALCIUM ABSORPTION, AND DIFFERENCES IN SW PRODUCED BY LOWER DOSES OF WHEAT BRAN WOULD PROBABLY NOT BE AS GREAT. THE BULK (GREATER THAN OR EQUAL TO 80%) OF A SINGLE DOSE OF A FECAL MARKER, CHROMIUM SESQUIOXIDE, WHICH COULD BE INCORPORATED INTO A SPECIFIC DAY'S FIBER SUPPLEMENT, WAS RECOVERED IN 5 DAYS OF EXCRETION DURING THE CONTROL PERIOD AND IN 4 DAYS DURING THE BRAN PERIOD. HOWEVER, THE BLUE COLOR OF THE CHROMIUM BEFORE INGESTION IS CLEARLY A NEGATIVE FEATURE. ANOTHER MARKER, POLYETHYLENE GLYCOL, COULD NOT BE RECOVERED IN EXCRETA WHEN TRANSIENT TIME WAS 4 DAYS OR MORE. IN A SEPARATE STUDY, DEMONSTRATION OF VERY LITTLE OVERLAP IN THE CONCENTRATION OF FECAL NEUTRAL DETERGENT FIBER BETWEEN THE CONTROL AND BRAN PERIODS SUGGESTS THAT FECAL FIBER MAY BE A MARKER OF COMPLIANCE WITH A FIBER SUPPLEMENT."
1237630,Paschin et al. 1982,Dominant lethals induced in male mice by low dose of potassium dichromate,ANEUPLOIDY FILE/ORNL,Dominant lethals induced in male mice by low dose of potassium dichromate Abs: ANEUPLOIDY FILE/ORNL
1237628,Price-Jones et al. 1980,The genetic effects of crocidolite asbestos: Comparison of chromosome abnormalities and sister-chromatid exchanges,"The genetic effects of crocidolite asbestos in Chinese hamster V79-4 cells are compared with those of potassium chromate and Min-u-Sil silica. Potassium chromate, a known mutagen, increased the frequency of SCE. Neither crocidolite nor silica induced SCE, even though crocidolite caused numerical changes in the karyotype.","The genetic effects of crocidolite asbestos: Comparison of chromosome abnormalities and sister-chromatid exchanges Abs: The genetic effects of crocidolite asbestos in Chinese hamster V79-4 cells are compared with those of potassium chromate and Min-u-Sil silica. Potassium chromate, a known mutagen, increased the frequency of SCE. Neither crocidolite nor silica induced SCE, even though crocidolite caused numerical changes in the karyotype."
1237621,Golomb et al. 1990,"Relationship between drug release rate, particle size and swelling of silicone matrices","IPA COPYRIGHT: ASHP The relationship between drug particle size, release rate and swelling of silastic matrices was examined by using the model drug potassium dichromate and 2 types of silicone polymer--silastic 382 (I) and silastic Q7-4840 (II), both variations of silicone rubber. The drug particles were found to be the driving force for water uptake by the matrix. The release rate was directly proportional to the degree of swelling, which in turn was directly proportional to drug particle size. The release rate and swelling of matrices composed of I increased with decreasing drug particle size, while increasing drug particle size resulted in increased release rate and decreased swelling of II matrices, probably because air is entrapped during fabrication of these matrices. More retarded release and swelling was exhibited by II matrices in comparison to matrices composed of I, probably due to the different physical properties of these silicones.","Relationship between drug release rate, particle size and swelling of silicone matrices Abs: IPA COPYRIGHT: ASHP The relationship between drug particle size, release rate and swelling of silastic matrices was examined by using the model drug potassium dichromate and 2 types of silicone polymer--silastic 382 (I) and silastic Q7-4840 (II), both variations of silicone rubber. The drug particles were found to be the driving force for water uptake by the matrix. The release rate was directly proportional to the degree of swelling, which in turn was directly proportional to drug particle size. The release rate and swelling of matrices composed of I increased with decreasing drug particle size, while increasing drug particle size resulted in increased release rate and decreased swelling of II matrices, probably because air is entrapped during fabrication of these matrices. More retarded release and swelling was exhibited by II matrices in comparison to matrices composed of I, probably due to the different physical properties of these silicones."
1237620,Wiesenauer et al. 1989,Efficiency of homeopathic drug combinations for the treatment of sinusitis: results of a randomized double blind study with general practitioners,"IPA COPYRIGHT: ASHP A double blind, placebo controlled, randomized trial of homeopathic drug preparations containing potassium dichromate, cinnabar and Luffa operculata in various combinations administered in tablet form for the treatment of sinusitis in 152 patients is described. No remarkable difference was observed in the therapeutic success between the homeopathic preparations and placebo.","Efficiency of homeopathic drug combinations for the treatment of sinusitis: results of a randomized double blind study with general practitioners Abs: IPA COPYRIGHT: ASHP A double blind, placebo controlled, randomized trial of homeopathic drug preparations containing potassium dichromate, cinnabar and Luffa operculata in various combinations administered in tablet form for the treatment of sinusitis in 152 patients is described. No remarkable difference was observed in the therapeutic success between the homeopathic preparations and placebo."
1237618,Gatta et al. 1985,"Derivatives of 2,3-benzodiazepine","IPA COPYRIGHT: ASHP A variety of 2,3-benzodiazepines and 2,3-benzodiazepin-4-ones were synthesized by chromium trioxide oxidation of 1-arylisochromans, followed by condensation with hydrazine of the resulting dicarbonyl compounds. Pharmacological screening was conducted for determination of benzodiazepine receptor activity.","Derivatives of 2,3-benzodiazepine Abs: IPA COPYRIGHT: ASHP A variety of 2,3-benzodiazepines and 2,3-benzodiazepin-4-ones were synthesized by chromium trioxide oxidation of 1-arylisochromans, followed by condensation with hydrazine of the resulting dicarbonyl compounds. Pharmacological screening was conducted for determination of benzodiazepine receptor activity."
1237616,Bobarevic and  Lovren 1983,Preparation on secobarbitone oxidation derivatives and their identification by TLC,IPA COPYRIGHT: ASHP Secobarbitone (secobarbital) oxidation products were obtained by reaction with potassium bichromate and separated and identifed by TLC.,Preparation on secobarbitone oxidation derivatives and their identification by TLC Abs: IPA COPYRIGHT: ASHP Secobarbitone (secobarbital) oxidation products were obtained by reaction with potassium bichromate and separated and identifed by TLC.
1237613,Soviar et al. 1980,Proposition for proving barium salts as impurities in some drugs,IPA COPYRIGHT: ASHP The detection of barium salt impurities in drug products was investigated using both compendial and unofficial methods. The preferred method utilized dilute sulfuric acid and potassium chromate reagents. A method using sodium rhodizonate was more sensitive but was unofficial. An official method using calcium sulfate saturated solution lacked sensitivity.,Proposition for proving barium salts as impurities in some drugs Abs: IPA COPYRIGHT: ASHP The detection of barium salt impurities in drug products was investigated using both compendial and unofficial methods. The preferred method utilized dilute sulfuric acid and potassium chromate reagents. A method using sodium rhodizonate was more sensitive but was unofficial. An official method using calcium sulfate saturated solution lacked sensitivity.
1237612,Branch and  Cummings 1978,Comparison of radiopaque pellets and chromium sesquioxide as inert markers in studies requiring accurate fecal collections,"IPA COPYRIGHT: ASHP Radiopaque pellets (I) similar to those currently used to measure GI transit time were compared with chromium sesquioxide (II; dichromium trioxide) in 5 healthy subjects, aged 22-24, to assess their suitability for use as inert markers in the gut. Gelatin capsules were filled each with 10 pellets of I, while II was in 250 mg capsules. The subjects were fed one capsule of each marker with each meal (3/day), a total daily dose of 30 pellets of I and 750 mg of II, for 2 separate 3 week periods, while taking metabolically controlled diets. The radiopaque markers were analyzed by radiographing each individual stool. Overall recovery of both markers was satisfactory (99.7% for I and 97.8% for II). A comparison of the amount of each marker recovered in 69 separate fecal collection periods of various lengths showed close agreement. The amount of marker retained in the gut was 13.5% greater for II at the end of the 3 week study periods. I offers clear advantages over II, being considerably easier and quicker to measure, the method of measurement using x-rays does not alter the stools and fecal handling is minimized. The precision of I measurement is greater and, because of the variety available, more flexibility for metabolic studies is offered.","Comparison of radiopaque pellets and chromium sesquioxide as inert markers in studies requiring accurate fecal collections Abs: IPA COPYRIGHT: ASHP Radiopaque pellets (I) similar to those currently used to measure GI transit time were compared with chromium sesquioxide (II; dichromium trioxide) in 5 healthy subjects, aged 22-24, to assess their suitability for use as inert markers in the gut. Gelatin capsules were filled each with 10 pellets of I, while II was in 250 mg capsules. The subjects were fed one capsule of each marker with each meal (3/day), a total daily dose of 30 pellets of I and 750 mg of II, for 2 separate 3 week periods, while taking metabolically controlled diets. The radiopaque markers were analyzed by radiographing each individual stool. Overall recovery of both markers was satisfactory (99.7% for I and 97.8% for II). A comparison of the amount of each marker recovered in 69 separate fecal collection periods of various lengths showed close agreement. The amount of marker retained in the gut was 13.5% greater for II at the end of the 3 week study periods. I offers clear advantages over II, being considerably easier and quicker to measure, the method of measurement using x-rays does not alter the stools and fecal handling is minimized. The precision of I measurement is greater and, because of the variety available, more flexibility for metabolic studies is offered."
1237611,James and  Tsirivas 1977,Colorimetric method for determining hydrogen peroxide in emulsions,"IPA COPYRIGHT: ASHP A method was developed for the colorimetric determination of hydrogen peroxide (I) which is dependent on the intensity of the blue color obtained with potassium dichromate. The method was used to determine I in 2 hair bleaching cosmetic emulsions. The effects on the method of some surfactants--cetrimide, sodium laurylether sulfate (Texapon N-25) and an ethoxylated lanolin derivative (Solan E)--were investigated by incorporating each in turn into a I solution of known concentration.","Colorimetric method for determining hydrogen peroxide in emulsions Abs: IPA COPYRIGHT: ASHP A method was developed for the colorimetric determination of hydrogen peroxide (I) which is dependent on the intensity of the blue color obtained with potassium dichromate. The method was used to determine I in 2 hair bleaching cosmetic emulsions. The effects on the method of some surfactants--cetrimide, sodium laurylether sulfate (Texapon N-25) and an ethoxylated lanolin derivative (Solan E)--were investigated by incorporating each in turn into a I solution of known concentration."
1237610,Cohen 1976,"Intestinal blood loss after a new anti-inflammatory drug, sulindac","IPA COPYRIGHT: ASHP Sulindac (I) was tested for fecal blood loss in 40 healthy male subjects whose red cells had been labeled with radioactive sodium chromate. Two daily dose levels of 240 mg and 400 mg were compared with 4.8 gm of aspirin (II) and placebo for 2 weeks. At day 15, II induced blood loss was greater than that of both dose levels of I and of placebo (p |LT/ 0.05). There were no significant differences between the 2 sulindac groups and the placebo group. II caused more adverse reactions than I, 240 mg (p |LT/ 0.05), 400 mg (p |LT/ 0.05), and placebo (p |LT/ 0.05).","Intestinal blood loss after a new anti-inflammatory drug, sulindac Abs: IPA COPYRIGHT: ASHP Sulindac (I) was tested for fecal blood loss in 40 healthy male subjects whose red cells had been labeled with radioactive sodium chromate. Two daily dose levels of 240 mg and 400 mg were compared with 4.8 gm of aspirin (II) and placebo for 2 weeks. At day 15, II induced blood loss was greater than that of both dose levels of I and of placebo (p |LT/ 0.05). There were no significant differences between the 2 sulindac groups and the placebo group. II caused more adverse reactions than I, 240 mg (p |LT/ 0.05), 400 mg (p |LT/ 0.05), and placebo (p |LT/ 0.05)."
1237609,Sanvordeker and  Dajani 1975,In vitro adsorption of diphenoxylate hydrochloride on activated charcoal and its relationship to pharmacological effects of drug in vivo. 1,"IPA COPYRIGHT: ASHP The adsorption of diphenoxylate hydrochloride (I) on activated charcoal (II) powder was studied in vitro. Langmuir adsorption isotherms were established at pH 4 and 7, and the maximum adsorption capacity was estimated using these values. II modified the bioavailability of I in vivo. The antipropulsive aciton of I in the mouse was strongly inhibited in the presence of II. A comparative evaluation of II and chromium oxide, used as an inert, nonabsorbable marker, revealed that chromium oxide may be the marker of choice in gastrointestinal transit studies in laboratory animals since it does not influence the availability of I. The clinical implications for the management of I overdose in children are discussed.","In vitro adsorption of diphenoxylate hydrochloride on activated charcoal and its relationship to pharmacological effects of drug in vivo. 1 Abs: IPA COPYRIGHT: ASHP The adsorption of diphenoxylate hydrochloride (I) on activated charcoal (II) powder was studied in vitro. Langmuir adsorption isotherms were established at pH 4 and 7, and the maximum adsorption capacity was estimated using these values. II modified the bioavailability of I in vivo. The antipropulsive aciton of I in the mouse was strongly inhibited in the presence of II. A comparative evaluation of II and chromium oxide, used as an inert, nonabsorbable marker, revealed that chromium oxide may be the marker of choice in gastrointestinal transit studies in laboratory animals since it does not influence the availability of I. The clinical implications for the management of I overdose in children are discussed."
1237608,Carmichael et al. 1973,Tracer microspheres as a fecal marker in balance studies,IPA COPYRIGHT: ASHP Chromium (Cr 51) particles with an average diameter of 50 microns were compared with chromium sesquioxide (I) and beta-sitosterol (II) in 5 healthy male volunteers as fecal markers. The chromium particles were found to be an ideal fecal marker in all aspects and appeared to offer several advantages over I and II. These include: (1) direct and accurate measurement without complex analytical procedures; (2) minimal direct handling of the specimen; (3) lack of toxicity or degradation; and (4) uniform dispersion in feces and total recoverability.,Tracer microspheres as a fecal marker in balance studies Abs: IPA COPYRIGHT: ASHP Chromium (Cr 51) particles with an average diameter of 50 microns were compared with chromium sesquioxide (I) and beta-sitosterol (II) in 5 healthy male volunteers as fecal markers. The chromium particles were found to be an ideal fecal marker in all aspects and appeared to offer several advantages over I and II. These include: (1) direct and accurate measurement without complex analytical procedures; (2) minimal direct handling of the specimen; (3) lack of toxicity or degradation; and (4) uniform dispersion in feces and total recoverability.
1237604,Mcintyre et al. 1970,Current procedures for scanning of the spleen,"IPA COPYRIGHT: ASHP The functions of the spleen provide the basis for spleen scanning: moderately damaged erythrocytes are specifically sequestered in the splenic sinusoids and the reticuloendothelial cells of the spleen, as well as those of other organs, accumulate intravenously administered solloidal particles by the process of phagocytosis. Damaged erythrocytes labeled with 197Hg-1-mercuri-2-hydroxypropane (MHP), 203Hg-MHP, chromium-51 sodium chromate or rubidium-81 chloride or colloidal preparations including gold-198 colloid, technetium-99m sulfur colloid, or indium-113m colloid can therefore be used to obtain scanning images of the spleen. Although several methods are adequate for the majority of clinical problems, the collodial preparations labeled with short-lived nuclides are preferred for routine use.","Current procedures for scanning of the spleen Abs: IPA COPYRIGHT: ASHP The functions of the spleen provide the basis for spleen scanning: moderately damaged erythrocytes are specifically sequestered in the splenic sinusoids and the reticuloendothelial cells of the spleen, as well as those of other organs, accumulate intravenously administered solloidal particles by the process of phagocytosis. Damaged erythrocytes labeled with 197Hg-1-mercuri-2-hydroxypropane (MHP), 203Hg-MHP, chromium-51 sodium chromate or rubidium-81 chloride or colloidal preparations including gold-198 colloid, technetium-99m sulfur colloid, or indium-113m colloid can therefore be used to obtain scanning images of the spleen. Although several methods are adequate for the majority of clinical problems, the collodial preparations labeled with short-lived nuclides are preferred for routine use."
1237603,Patierno 1997,PARTICULATE CHROMIUM TOXICITY AND CARCINOGENESIS,"Certain chromium compounds are environmentally and occupationally important human respiratory toxins and carcinogens. The forms of chromium most frequently associated with human exposure, toxicity and carcinogenesis are particulate salts of low solubility (lead chromate), which deposit and persist in the respiratory tract after inhalation. Lead chromate particles are genotoxic to cultured fibroblasts, but although the particles can be phagocytized, the genotoxicity is dependent on extracellular dissolution of particles at the cell surface microenvironment which is markedly accelerated by particle-cell contact. The particle-derived dissolved hexavalent chromate oxyanion enters the cell where it undergoes a uniquely complex scheme of reductive metabolism, producing a cascade of reactive intermediates each of which appears to produce a specific form of DNA damage. The spectrum of DNA damage includes adduct formation, strand breaks, chromosomal aberrations, DNA-protein crosslinks and DNA-DNA crosslinks which constitute a base-specific polymerase arresting lesion both in vitro and in vivo. Intracellular reduction of chromium also produces reactive oxygen species. The combination of direct DNA damage and indirect oxidative stress alters DNA replication and transcription, interferes with the cell cycle and provokes cell commitment to apoptotic cell death, terminal differentiation, or neoplastic transformation. The DNA damage and cell fate endpoints can be markedly altered by antioxidants suggesting the partial involvement of oxidative damage. The overall objective of this continuation application is to investigate the interaction of particulate chromium compounds with human respiratory epithelial cells which are the main targets of chromium toxicity and carcinogenesis. We will examine the mechanisms of cellular toxicity and their role in chromium-induced cell fate, focusing on DNA replication and oxidative stress. We will test the following hypotheses: 1) that particulate chromium compounds will cause genotoxicity and apoptotic cell death, in human respiratory epithelial and stromal cells, and to determine whether the genotoxicity is dependent on particle-cell contact, phagocytosis, and/or cell-enhanced dissolution of particles in the cell microenvironment, 2) that the toxicity and genotoxicity of particulate chromium compounds in human respiratory epithelial cells will be modulated by the presence of co-cultured fibroblasts and/or inflammatory cells, 3) that oxidative stress contributes tot he toxicity, genotoxicity and apoptotic cell death caused by particulate chromium compounds in human respiratory epithelial and stromal cells, and 4) that specific reductive chromium metabolites and types of chromium-induced DNA damage differentially affect the process of DNA replication. This research will have practical value in evaluating the relative risk to humans in contact with particulate chromates and will also help elucidate cellular and molecular mechanisms of toxicity and carcinogenesis.","PARTICULATE CHROMIUM TOXICITY AND CARCINOGENESIS Abs: Certain chromium compounds are environmentally and occupationally important human respiratory toxins and carcinogens. The forms of chromium most frequently associated with human exposure, toxicity and carcinogenesis are particulate salts of low solubility (lead chromate), which deposit and persist in the respiratory tract after inhalation. Lead chromate particles are genotoxic to cultured fibroblasts, but although the particles can be phagocytized, the genotoxicity is dependent on extracellular dissolution of particles at the cell surface microenvironment which is markedly accelerated by particle-cell contact. The particle-derived dissolved hexavalent chromate oxyanion enters the cell where it undergoes a uniquely complex scheme of reductive metabolism, producing a cascade of reactive intermediates each of which appears to produce a specific form of DNA damage. The spectrum of DNA damage includes adduct formation, strand breaks, chromosomal aberrations, DNA-protein crosslinks and DNA-DNA crosslinks which constitute a base-specific polymerase arresting lesion both in vitro and in vivo. Intracellular reduction of chromium also produces reactive oxygen species. The combination of direct DNA damage and indirect oxidative stress alters DNA replication and transcription, interferes with the cell cycle and provokes cell commitment to apoptotic cell death, terminal differentiation, or neoplastic transformation. The DNA damage and cell fate endpoints can be markedly altered by antioxidants suggesting the partial involvement of oxidative damage. The overall objective of this continuation application is to investigate the interaction of particulate chromium compounds with human respiratory epithelial cells which are the main targets of chromium toxicity and carcinogenesis. We will examine the mechanisms of cellular toxicity and their role in chromium-induced cell fate, focusing on DNA replication and oxidative stress. We will test the following hypotheses: 1) that particulate chromium compounds will cause genotoxicity and apoptotic cell death, in human respiratory epithelial and stromal cells, and to determine whether the genotoxicity is dependent on particle-cell contact, phagocytosis, and/or cell-enhanced dissolution of particles in the cell microenvironment, 2) that the toxicity and genotoxicity of particulate chromium compounds in human respiratory epithelial cells will be modulated by the presence of co-cultured fibroblasts and/or inflammatory cells, 3) that oxidative stress contributes tot he toxicity, genotoxicity and apoptotic cell death caused by particulate chromium compounds in human respiratory epithelial and stromal cells, and 4) that specific reductive chromium metabolites and types of chromium-induced DNA damage differentially affect the process of DNA replication. This research will have practical value in evaluating the relative risk to humans in contact with particulate chromates and will also help elucidate cellular and molecular mechanisms of toxicity and carcinogenesis."
1237602,Dixon 1997,MOLECULAR MECHANISMS OF CHROMIUM MUTAGENESIS [GRANT PROPOSAL],"Chromium has been identified as a ""primary hazardous substance"" at a large proportion of the Superfund Hazardous Waste Sites. Epidemiological studies have linked the exposure to chromium compounds in the work place to increased risk for development of lung cancer. Furthermore, certain forms of chromium have been shown to be carcinogenic in animals and mutagenic in bacteria and mammalian cell systems. Although the process of carcinogenesis is complex, it is clear that mutagenic activation of proto-oncogenes plays an important role. The purpose of the research proposed here is to understand the mechanisms by which chromium causes mutations in mammalian cells and to provide a link between the mutagenic and carcinogenic activities of chromium. We are using shuttle vectors in cultured mammalian cells and yeast to identify premutagenic DNA damage induced by chromium compounds and to determine the mutagenic specificity of this damage. We are also using a mammalian in vitro DNA replication system to investigate how the cellular DNA replication apparatus responds to chromium-induced template damage and whether DNA replication fidelity is affected by direct effects of chromium on DNA replication factors. In addition, we are seeking a link between chromium mutagenesis and carcinogenesis by using transgenic mice to examine the mutagenic effects of inhaled calcium chromate dust in the lung - the target organ for chromium carcinogenesis. The focus of this work will be to understand the role that biotransformation of chromium within the cell plays in the mutagenic activation of the compound. Apparently, chromium enters the cells as Cr(VI) where it can be reduced to reactive species Cr(V), Cr(VI) and Cr(III). Although a number of cellular macromolecules have been implicated in these transformations, it appears that intracellular glutathione may play a key role in chromium reduction and mutagenesis. We propose to test the following hypothesis: The intracellular reduction of chromium by glutathione is a major pathway for the generation of reactive intermediates that are responsible for chromium mutagenesis in the intact cell and for chromium carcinogenesis in animals. By comparing the spectra of mutations induced in a mutagenesis target gene by chromium compounds when plasmid DNA is treated in vitro and replicated in yeast or mammalian cells, when yeast or mammalian cells that contain plasmid are treated with chromium, and in the transgene in the lungs of mice following chromium inhalation, we hope to identify the types of premutagenic DNA damage that are important in chromium mutagenesis and determine how the mutagenic specificity is determined by the specific pathway for chromium reduction in the cell. An increased understanding of the mechanisms of chromium mutagenesis, should enhance our ability to evaluate the risks associated with human exposure to the environmental hazard, and perhaps suggest methods for intervention and prevention of adverse health effects of exposure.","MOLECULAR MECHANISMS OF CHROMIUM MUTAGENESIS [GRANT PROPOSAL] Abs: Chromium has been identified as a ""primary hazardous substance"" at a large proportion of the Superfund Hazardous Waste Sites. Epidemiological studies have linked the exposure to chromium compounds in the work place to increased risk for development of lung cancer. Furthermore, certain forms of chromium have been shown to be carcinogenic in animals and mutagenic in bacteria and mammalian cell systems. Although the process of carcinogenesis is complex, it is clear that mutagenic activation of proto-oncogenes plays an important role. The purpose of the research proposed here is to understand the mechanisms by which chromium causes mutations in mammalian cells and to provide a link between the mutagenic and carcinogenic activities of chromium. We are using shuttle vectors in cultured mammalian cells and yeast to identify premutagenic DNA damage induced by chromium compounds and to determine the mutagenic specificity of this damage. We are also using a mammalian in vitro DNA replication system to investigate how the cellular DNA replication apparatus responds to chromium-induced template damage and whether DNA replication fidelity is affected by direct effects of chromium on DNA replication factors. In addition, we are seeking a link between chromium mutagenesis and carcinogenesis by using transgenic mice to examine the mutagenic effects of inhaled calcium chromate dust in the lung - the target organ for chromium carcinogenesis. The focus of this work will be to understand the role that biotransformation of chromium within the cell plays in the mutagenic activation of the compound. Apparently, chromium enters the cells as Cr(VI) where it can be reduced to reactive species Cr(V), Cr(VI) and Cr(III). Although a number of cellular macromolecules have been implicated in these transformations, it appears that intracellular glutathione may play a key role in chromium reduction and mutagenesis. We propose to test the following hypothesis: The intracellular reduction of chromium by glutathione is a major pathway for the generation of reactive intermediates that are responsible for chromium mutagenesis in the intact cell and for chromium carcinogenesis in animals. By comparing the spectra of mutations induced in a mutagenesis target gene by chromium compounds when plasmid DNA is treated in vitro and replicated in yeast or mammalian cells, when yeast or mammalian cells that contain plasmid are treated with chromium, and in the transgene in the lungs of mice following chromium inhalation, we hope to identify the types of premutagenic DNA damage that are important in chromium mutagenesis and determine how the mutagenic specificity is determined by the specific pathway for chromium reduction in the cell. An increased understanding of the mechanisms of chromium mutagenesis, should enhance our ability to evaluate the risks associated with human exposure to the environmental hazard, and perhaps suggest methods for intervention and prevention of adverse health effects of exposure."
1237601,Kane 1998,MECHANISMS UNDERLYING SEGMENT-SPECIFIC NEPHROTOXICITY [GRANT PROPOSAL],"Previous in vivo and in vitro research has demonstrated that most nephrotoxic chemicals induce selective injury within the kidney effecting either renal proximal straight (PST) or proximal convoluted (PCT) tubules. Selective injury observed in vitro suggests that innate cellular differences in metabolism and/or transport exist which may explain why each of these segments is susceptible to specific nephrotoxicants. Biochemical investigations to elucidate these innate cellular mechanisms in PST and PCT segments have been difficult to study due to the lack of tissue mass or a mixed population of tubular cell types in most preparations. Recently a new method was developed to isolate PST and PCT segments from one another in bulk making it possible to now compare and contrast basic mechanistic differences which render these segments innately susceptible to nephrotoxicant injury. The major goals of this proposal are to systematically investigate segment- specific metabolism- and transport-dependent mechanisms of nephrotoxicity by measuring the differential distribution or activity of several drug metabolizing enzymes and epithelial transport systems which may predispose specific nephron segments to nephrotoxic injury. this research should provide mechanistic information needed to develop rational approaches for preventing many forms of chemically-induced renal injuries. In these studies PST and PCT segments will be respectively isolated from the outer stripe region of the renal medulla or from the outer regions of the renal cortex using bulk dissection and standard Percoll gradient separation techniques. Once isolated and the purity characterized by marker enzyme analysis and histological examination, both fractions will be examined for various metabolic (e.g. glycolytic and gluconeogenic capacities, substrate utilization preferences), biochemical (e.g. rates of oxygen consumption, glutathione metabolism, phase I and II biotransformation enzyme activities), and transport (rates of organic acid, base, sugar and amino acid transport) differences. These measurements will be used to elucidate the differences in normal functions which might render the particular tubular segment susceptible to specific toxicant induced injury. In vitro exposure of both proximal tubular fractions to toxicants which effect either PST (acetaminophen, cis-platinum, hexachlorobutadiene, mercuric chloride) or PCT (hypoxia/anoxia, ethylene dibromide, potassium dichromate) will then be conducted to determine the mechanistic role of metabolism and transport as they relate to the pathophysiology of nephron specific injury. Additional studies will be conducted to: (1) manipulate the targeting of chemical gents to specific cell types (selective segmental delivery) through complexation of metals with specific carriers (cysteine or metallothionine); (2) evaluate the toxic consequences of delivering chemicals to the apical verses the basolateral cell surfaces; and (3) evaluate the interactive role between liver metabolism and nephrotoxicity in vitro by evaluating alterations in nephrotoxic responses in the presence and absence of liver tissue (co-incubations of liver and kidney tissues).","MECHANISMS UNDERLYING SEGMENT-SPECIFIC NEPHROTOXICITY [GRANT PROPOSAL] Abs: Previous in vivo and in vitro research has demonstrated that most nephrotoxic chemicals induce selective injury within the kidney effecting either renal proximal straight (PST) or proximal convoluted (PCT) tubules. Selective injury observed in vitro suggests that innate cellular differences in metabolism and/or transport exist which may explain why each of these segments is susceptible to specific nephrotoxicants. Biochemical investigations to elucidate these innate cellular mechanisms in PST and PCT segments have been difficult to study due to the lack of tissue mass or a mixed population of tubular cell types in most preparations. Recently a new method was developed to isolate PST and PCT segments from one another in bulk making it possible to now compare and contrast basic mechanistic differences which render these segments innately susceptible to nephrotoxicant injury. The major goals of this proposal are to systematically investigate segment- specific metabolism- and transport-dependent mechanisms of nephrotoxicity by measuring the differential distribution or activity of several drug metabolizing enzymes and epithelial transport systems which may predispose specific nephron segments to nephrotoxic injury. this research should provide mechanistic information needed to develop rational approaches for preventing many forms of chemically-induced renal injuries. In these studies PST and PCT segments will be respectively isolated from the outer stripe region of the renal medulla or from the outer regions of the renal cortex using bulk dissection and standard Percoll gradient separation techniques. Once isolated and the purity characterized by marker enzyme analysis and histological examination, both fractions will be examined for various metabolic (e.g. glycolytic and gluconeogenic capacities, substrate utilization preferences), biochemical (e.g. rates of oxygen consumption, glutathione metabolism, phase I and II biotransformation enzyme activities), and transport (rates of organic acid, base, sugar and amino acid transport) differences. These measurements will be used to elucidate the differences in normal functions which might render the particular tubular segment susceptible to specific toxicant induced injury. In vitro exposure of both proximal tubular fractions to toxicants which effect either PST (acetaminophen, cis-platinum, hexachlorobutadiene, mercuric chloride) or PCT (hypoxia/anoxia, ethylene dibromide, potassium dichromate) will then be conducted to determine the mechanistic role of metabolism and transport as they relate to the pathophysiology of nephron specific injury. Additional studies will be conducted to: (1) manipulate the targeting of chemical gents to specific cell types (selective segmental delivery) through complexation of metals with specific carriers (cysteine or metallothionine); (2) evaluate the toxic consequences of delivering chemicals to the apical verses the basolateral cell surfaces; and (3) evaluate the interactive role between liver metabolism and nephrotoxicity in vitro by evaluating alterations in nephrotoxic responses in the presence and absence of liver tissue (co-incubations of liver and kidney tissues)."
1237600,Patierno 1998,PARTICULATE CHROMIUM TOXICITY AND CARCINOGENESIS,"Certain chromium compounds are environmentally and occupationally important human respiratory toxins and carcinogens. The forms of chromium most frequently associated with human exposure, toxicity and carcinogenesis are particulate salts of low solubility (lead chromate), which deposit and persist in the respiratory tract after inhalation. Lead chromate particles are genotoxic to cultured fibroblasts, but although the particles can be phagocytized, the genotoxicity is dependent on extracellular dissolution of particles at the cell surface microenvironment which is markedly accelerated by particle-cell contact. The particle-derived dissolved hexavalent chromate oxyanion enters the cell where it undergoes a uniquely complex scheme of reductive metabolism, producing a cascade of reactive intermediates each of which appears to produce a specific form of DNA damage. The spectrum of DNA damage includes adduct formation, strand breaks, chromosomal aberrations, DNA-protein crosslinks and DNA-DNA crosslinks which constitute a base-specific polymerase arresting lesion both in vitro and in vivo. Intracellular reduction of chromium also produces reactive oxygen species. The combination of direct DNA damage and indirect oxidative stress alters DNA replication and transcription, interferes with the cell cycle and provokes cell commitment to apoptotic cell death, terminal differentiation, or neoplastic transformation. The DNA damage and cell fate endpoints can be markedly altered by antioxidants suggesting the partial involvement of oxidative damage. The overall objective of this continuation application is to investigate the interaction of particulate chromium compounds with human respiratory epithelial cells which are the main targets of chromium toxicity and carcinogenesis. We will examine the mechanisms of cellular toxicity and their role in chromium-induced cell fate, focusing on DNA replication and oxidative stress. We will test the following hypotheses: 1) that particulate chromium compounds will cause genotoxicity and apoptotic cell death, in human respiratory epithelial and stromal cells, and to determine whether the genotoxicity is dependent on particle-cell contact, phagocytosis, and/or cell-enhanced dissolution of particles in the cell microenvironment, 2) that the toxicity and genotoxicity of particulate chromium compounds in human respiratory epithelial cells will be modulated by the presence of co-cultured fibroblasts and/or inflammatory cells, 3) that oxidative stress contributes tot he toxicity, genotoxicity and apoptotic cell death caused by particulate chromium compounds in human respiratory epithelial and stromal cells, and 4) that specific reductive chromium metabolites and types of chromium-induced DNA damage differentially affect the process of DNA replication. This research will have practical value in evaluating the relative risk to humans in contact with particulate chromates and will also help elucidate cellular and molecular mechanisms of toxicity and carcinogenesis.","PARTICULATE CHROMIUM TOXICITY AND CARCINOGENESIS Abs: Certain chromium compounds are environmentally and occupationally important human respiratory toxins and carcinogens. The forms of chromium most frequently associated with human exposure, toxicity and carcinogenesis are particulate salts of low solubility (lead chromate), which deposit and persist in the respiratory tract after inhalation. Lead chromate particles are genotoxic to cultured fibroblasts, but although the particles can be phagocytized, the genotoxicity is dependent on extracellular dissolution of particles at the cell surface microenvironment which is markedly accelerated by particle-cell contact. The particle-derived dissolved hexavalent chromate oxyanion enters the cell where it undergoes a uniquely complex scheme of reductive metabolism, producing a cascade of reactive intermediates each of which appears to produce a specific form of DNA damage. The spectrum of DNA damage includes adduct formation, strand breaks, chromosomal aberrations, DNA-protein crosslinks and DNA-DNA crosslinks which constitute a base-specific polymerase arresting lesion both in vitro and in vivo. Intracellular reduction of chromium also produces reactive oxygen species. The combination of direct DNA damage and indirect oxidative stress alters DNA replication and transcription, interferes with the cell cycle and provokes cell commitment to apoptotic cell death, terminal differentiation, or neoplastic transformation. The DNA damage and cell fate endpoints can be markedly altered by antioxidants suggesting the partial involvement of oxidative damage. The overall objective of this continuation application is to investigate the interaction of particulate chromium compounds with human respiratory epithelial cells which are the main targets of chromium toxicity and carcinogenesis. We will examine the mechanisms of cellular toxicity and their role in chromium-induced cell fate, focusing on DNA replication and oxidative stress. We will test the following hypotheses: 1) that particulate chromium compounds will cause genotoxicity and apoptotic cell death, in human respiratory epithelial and stromal cells, and to determine whether the genotoxicity is dependent on particle-cell contact, phagocytosis, and/or cell-enhanced dissolution of particles in the cell microenvironment, 2) that the toxicity and genotoxicity of particulate chromium compounds in human respiratory epithelial cells will be modulated by the presence of co-cultured fibroblasts and/or inflammatory cells, 3) that oxidative stress contributes tot he toxicity, genotoxicity and apoptotic cell death caused by particulate chromium compounds in human respiratory epithelial and stromal cells, and 4) that specific reductive chromium metabolites and types of chromium-induced DNA damage differentially affect the process of DNA replication. This research will have practical value in evaluating the relative risk to humans in contact with particulate chromates and will also help elucidate cellular and molecular mechanisms of toxicity and carcinogenesis."
1237599,Dixon 1998,MOLECULAR MECHANISMS OF CHROMIUM MUTAGENESIS [GRANT PROPOSAL],"Chromium has been identified as a ""primary hazardous substance"" at a large proportion of the Superfund Hazardous Waste Sites. Epidemiological studies have linked the exposure to chromium compounds in the work place to increased risk for development of lung cancer. Furthermore, certain forms of chromium have been shown to be carcinogenic in animals and mutagenic in bacteria and mammalian cell systems. Although the process of carcinogenesis is complex, it is clear that mutagenic activation of proto-oncogenes plays an important role. The purpose of the research proposed here is to understand the mechanisms by which chromium causes mutations in mammalian cells and to provide a link between the mutagenic and carcinogenic activities of chromium. We are using shuttle vectors in cultured mammalian cells and yeast to identify premutagenic DNA damage induced by chromium compounds and to determine the mutagenic specificity of this damage. We are also using a mammalian in vitro DNA replication system to investigate how the cellular DNA replication apparatus responds to chromium-induced template damage and whether DNA replication fidelity is affected by direct effects of chromium on DNA replication factors. In addition, we are seeking a link between chromium mutagenesis and carcinogenesis by using transgenic mice to examine the mutagenic effects of inhaled calcium chromate dust in the lung - the target organ for chromium carcinogenesis. The focus of this work will be to understand the role that biotransformation of chromium within the cell plays in the mutagenic activation of the compound. Apparently, chromium enters the cells as Cr(VI) where it can be reduced to reactive species Cr(V), Cr(VI) and Cr(III). Although a number of cellular macromolecules have been implicated in these transformations, it appears that intracellular glutathione may play a key role in chromium reduction and mutagenesis. We propose to test the following hypothesis: The intracellular reduction of chromium by glutathione is a major pathway for the generation of reactive intermediates that are responsible for chromium mutagenesis in the intact cell and for chromium carcinogenesis in animals. By comparing the spectra of mutations induced in a mutagenesis target gene by chromium compounds when plasmid DNA is treated in vitro and replicated in yeast or mammalian cells, when yeast or mammalian cells that contain plasmid are treated with chromium, and in the transgene in the lungs of mice following chromium inhalation, we hope to identify the types of premutagenic DNA damage that are important in chromium mutagenesis and determine how the mutagenic specificity is determined by the specific pathway for chromium reduction in the cell. An increased understanding of the mechanisms of chromium mutagenesis, should enhance our ability to evaluate the risks associated with human exposure to the environmental hazard, and perhaps suggest methods for intervention and prevention of adverse health effects of exposure.","MOLECULAR MECHANISMS OF CHROMIUM MUTAGENESIS [GRANT PROPOSAL] Abs: Chromium has been identified as a ""primary hazardous substance"" at a large proportion of the Superfund Hazardous Waste Sites. Epidemiological studies have linked the exposure to chromium compounds in the work place to increased risk for development of lung cancer. Furthermore, certain forms of chromium have been shown to be carcinogenic in animals and mutagenic in bacteria and mammalian cell systems. Although the process of carcinogenesis is complex, it is clear that mutagenic activation of proto-oncogenes plays an important role. The purpose of the research proposed here is to understand the mechanisms by which chromium causes mutations in mammalian cells and to provide a link between the mutagenic and carcinogenic activities of chromium. We are using shuttle vectors in cultured mammalian cells and yeast to identify premutagenic DNA damage induced by chromium compounds and to determine the mutagenic specificity of this damage. We are also using a mammalian in vitro DNA replication system to investigate how the cellular DNA replication apparatus responds to chromium-induced template damage and whether DNA replication fidelity is affected by direct effects of chromium on DNA replication factors. In addition, we are seeking a link between chromium mutagenesis and carcinogenesis by using transgenic mice to examine the mutagenic effects of inhaled calcium chromate dust in the lung - the target organ for chromium carcinogenesis. The focus of this work will be to understand the role that biotransformation of chromium within the cell plays in the mutagenic activation of the compound. Apparently, chromium enters the cells as Cr(VI) where it can be reduced to reactive species Cr(V), Cr(VI) and Cr(III). Although a number of cellular macromolecules have been implicated in these transformations, it appears that intracellular glutathione may play a key role in chromium reduction and mutagenesis. We propose to test the following hypothesis: The intracellular reduction of chromium by glutathione is a major pathway for the generation of reactive intermediates that are responsible for chromium mutagenesis in the intact cell and for chromium carcinogenesis in animals. By comparing the spectra of mutations induced in a mutagenesis target gene by chromium compounds when plasmid DNA is treated in vitro and replicated in yeast or mammalian cells, when yeast or mammalian cells that contain plasmid are treated with chromium, and in the transgene in the lungs of mice following chromium inhalation, we hope to identify the types of premutagenic DNA damage that are important in chromium mutagenesis and determine how the mutagenic specificity is determined by the specific pathway for chromium reduction in the cell. An increased understanding of the mechanisms of chromium mutagenesis, should enhance our ability to evaluate the risks associated with human exposure to the environmental hazard, and perhaps suggest methods for intervention and prevention of adverse health effects of exposure."
1237598,Schlesinger 1999,O3 AND MODULATING CR TOXICITY AND THE LUNG,"Most studies of occupationally relevant chemical hazards have involved use of single contaminants, so the biological and safety implications from inhalation of realistic mixtures have commonly been ignored in evaluations related to worker health and safety. In this regard, chromium (Cr) is released with ozone (O3) during welding, and a major health hazard from inhalation exposure to Cr-containing materials is lung cancer; this is likely due largely to the insoluble Cr species in the fumes. However, the contribution from other co-inhalants in modulating Cr-initiated responses is not clear. Co-contaminants may change the pulmonary environment producing conditions which could enhance the formation and survival of Cr- initiated tumors. For example, it has been demonstrated that simultaneously-inhaled O3 increases the pulmonary retention of inhaled insoluble Cr particles; this could be part of a scenario which would ultimately give rise to conditions within the lungs conductive to the formation and survival of Cr-initiated neoplasia. This proposal investigates other mechanisms underlying the elevated lung cancer incidence in welders exposed welding fumes containing both Cr and O3. It is hypothesized that the carcinogenic potential of insoluble Cr(VI) in the lungs of hosts inhaling the Cr/O3 mixture is greater than that in hosts inhaling the Cr alone due to O3-mediated increases in the lung tissue burdens of Cr(VI) and/or augmentation of one or more of the documented genetic/epigenetic mechanisms associated with Cr-induced conversion of normal cells to transformed types (i.e., an enhancement in level of DNA damage, chromosomal aberrations, and/or induced increases in the activity of cell kinases known to regulate the expression of nascent oncogenes) arising from the effects of O3 upon mechanisms utilized for the intracellular of insoluble Cf(VI) particles. The project involves exposure of rats to atmospheres containing carcinogenic Cr(VI), namely calcium chromate, alone and in combination with O3. This study will improve our understanding of the mechanisms underlying the interaction between Cr and O3 in the lungs and the role which mixtures of air contaminants may play in pulmonary disease pathogenesis following exposure to realistic mixed atmospheres of occupational relevance.","O3 AND MODULATING CR TOXICITY AND THE LUNG Abs: Most studies of occupationally relevant chemical hazards have involved use of single contaminants, so the biological and safety implications from inhalation of realistic mixtures have commonly been ignored in evaluations related to worker health and safety. In this regard, chromium (Cr) is released with ozone (O3) during welding, and a major health hazard from inhalation exposure to Cr-containing materials is lung cancer; this is likely due largely to the insoluble Cr species in the fumes. However, the contribution from other co-inhalants in modulating Cr-initiated responses is not clear. Co-contaminants may change the pulmonary environment producing conditions which could enhance the formation and survival of Cr- initiated tumors. For example, it has been demonstrated that simultaneously-inhaled O3 increases the pulmonary retention of inhaled insoluble Cr particles; this could be part of a scenario which would ultimately give rise to conditions within the lungs conductive to the formation and survival of Cr-initiated neoplasia. This proposal investigates other mechanisms underlying the elevated lung cancer incidence in welders exposed welding fumes containing both Cr and O3. It is hypothesized that the carcinogenic potential of insoluble Cr(VI) in the lungs of hosts inhaling the Cr/O3 mixture is greater than that in hosts inhaling the Cr alone due to O3-mediated increases in the lung tissue burdens of Cr(VI) and/or augmentation of one or more of the documented genetic/epigenetic mechanisms associated with Cr-induced conversion of normal cells to transformed types (i.e., an enhancement in level of DNA damage, chromosomal aberrations, and/or induced increases in the activity of cell kinases known to regulate the expression of nascent oncogenes) arising from the effects of O3 upon mechanisms utilized for the intracellular of insoluble Cf(VI) particles. The project involves exposure of rats to atmospheres containing carcinogenic Cr(VI), namely calcium chromate, alone and in combination with O3. This study will improve our understanding of the mechanisms underlying the interaction between Cr and O3 in the lungs and the role which mixtures of air contaminants may play in pulmonary disease pathogenesis following exposure to realistic mixed atmospheres of occupational relevance."
1237597,Reinhold 1999,MECHANISM OF METAL ANTAGONISTIC EFFECT ON BPDE MUTANTS,"The long term goal of this research is to understand how multiple carcinogens interact with cells to produce cancer. Agreat deal of work has been done on the effect of individual carcinogens, but to better mimic the actual environment to which humans are exposed, studies must be performed examining the effect of multiple carcinogen exposure. This proposal will specifically examine the interaction of metals (chromium and nickel) and benz[a]alpyrene diol epoxide (BPDE), all common environmental carcinogens, on the mutant frequency of the hypoxanthine phosphoribosyltransferase (HPRT) gene in normal human fibroblasts. Previous work in applicant's laboratory has shown that normal human fibroblasts treated with either potassium dichromate or nickel subsulfide are refractive to the mutagenic effects of BPDE. This antagonistic effect can be inhibited if antioxidants are included in the cell medium during the treatment period, suggesting a role for reactive oxygen species. This proposal will examine, in more detail, the biochemical mechanism for this antagonistic effect. Two hypothesis will be directly tested. The first is that low concentrations of metals can act in a synergistic way with BPDE to induce the activity of DNA repair enzymes. This hypothesis will be tested by directly measuring the DNA repair capability of cells treated with chromium or nickel and BPDE with untreated cells or cells treated with only one of the carcinogens. This hypothesis will be further tested by repeating experiments which showed the antagonistic effect with repair deficient cell lines. The antagonistic effect should not be observed in these cell lines if DNA repair processes are responsible for the antagonistic effect. The second hypothesis that will be tested is that low concentrations of metals can act synergistically with BPDE to cause inhibition of cell cycle progression. This could cause a reduction in the mutant frequency of BPDE by giving the cell more time to repair damaged DNA prior to DNA replication. Possible effects on the cell cycle will be tested by directly measuring the progression of cells through G and into S phase in the presence of metal and BPDE, and comparing that to untreated cells and cells treated with only one of the carcinogens. In addition, expression of proteins known to inhibit cell cycle progression from G to S phase will be determined, and the effect of plasmids carrying dominant-negative mutants of these cell cycle regulatory proteins will be examined.","MECHANISM OF METAL ANTAGONISTIC EFFECT ON BPDE MUTANTS Abs: The long term goal of this research is to understand how multiple carcinogens interact with cells to produce cancer. Agreat deal of work has been done on the effect of individual carcinogens, but to better mimic the actual environment to which humans are exposed, studies must be performed examining the effect of multiple carcinogen exposure. This proposal will specifically examine the interaction of metals (chromium and nickel) and benz[a]alpyrene diol epoxide (BPDE), all common environmental carcinogens, on the mutant frequency of the hypoxanthine phosphoribosyltransferase (HPRT) gene in normal human fibroblasts. Previous work in applicant's laboratory has shown that normal human fibroblasts treated with either potassium dichromate or nickel subsulfide are refractive to the mutagenic effects of BPDE. This antagonistic effect can be inhibited if antioxidants are included in the cell medium during the treatment period, suggesting a role for reactive oxygen species. This proposal will examine, in more detail, the biochemical mechanism for this antagonistic effect. Two hypothesis will be directly tested. The first is that low concentrations of metals can act in a synergistic way with BPDE to induce the activity of DNA repair enzymes. This hypothesis will be tested by directly measuring the DNA repair capability of cells treated with chromium or nickel and BPDE with untreated cells or cells treated with only one of the carcinogens. This hypothesis will be further tested by repeating experiments which showed the antagonistic effect with repair deficient cell lines. The antagonistic effect should not be observed in these cell lines if DNA repair processes are responsible for the antagonistic effect. The second hypothesis that will be tested is that low concentrations of metals can act synergistically with BPDE to cause inhibition of cell cycle progression. This could cause a reduction in the mutant frequency of BPDE by giving the cell more time to repair damaged DNA prior to DNA replication. Possible effects on the cell cycle will be tested by directly measuring the progression of cells through G and into S phase in the presence of metal and BPDE, and comparing that to untreated cells and cells treated with only one of the carcinogens. In addition, expression of proteins known to inhibit cell cycle progression from G to S phase will be determined, and the effect of plasmids carrying dominant-negative mutants of these cell cycle regulatory proteins will be examined."
1237596,Dixon 1999,MOLECULAR MECHANISMS OF CHROMIUM MUTAGENESIS,"Chromium has been identified as a ""primary hazardous substance"" at a large proportion of the Superfund Hazardous Waste Sites. Epidemiological studies have linked the exposure to chromium compounds in the work place to increased risk for development of lung cancer. Furthermore, certain forms of chromium have been shown to be carcinogenic in animals and mutagenic in bacteria and mammalian cell systems. Although the process of carcinogenesis is complex, it is clear that mutagenic activation of proto-oncogenes plays an important role. The purpose of the research proposed here is to understand the mechanisms by which chromium causes mutations in mammalian cells and to provide a link between the mutagenic and carcinogenic activities of chromium. We are using shuttle vectors in cultured mammalian cells and yeast to identify premutagenic DNA damage induced by chromium compounds and to determine the mutagenic specificity of this damage. We are also using a mammalian in vitro DNA replication system to investigate how the cellular DNA replication apparatus responds to chromium-induced template damage and whether DNA replication fidelity is affected by direct effects of chromium on DNA replication factors. In addition, we are seeking a link between chromium mutagenesis and carcinogenesis by using transgenic mice to examine the mutagenic effects of inhaled calcium chromate dust in the lung - the target organ for chromium carcinogenesis. The focus of this work will be to understand the role that biotransformation of chromium within the cell plays in the mutagenic activation of the compound. Apparently, chromium enters the cells as Cr(VI) where it can be reduced to reactive species Cr(V), Cr(VI) and Cr(III). Although a number of cellular macromolecules have been implicated in these transformations, it appears that intracellular glutathione may play a key role in chromium reduction and mutagenesis. We propose to test the following hypothesis: The intracellular reduction of chromium by glutathione is a major pathway for the generation of reactive intermediates that are responsible for chromium mutagenesis in the intact cell and for chromium carcinogenesis in animals. By comparing the spectra of mutations induced in a mutagenesis target gene by chromium compounds when plasmid DNA is treated in vitro and replicated in yeast or mammalian cells, when yeast or mammalian cells that contain plasmid are treated with chromium, and in the transgene in the lungs of mice following chromium inhalation, we hope to identify the types of premutagenic DNA damage that are important in chromium mutagenesis and determine how the mutagenic specificity is determined by the specific pathway for chromium reduction in the cell. An increased understanding of the mechanisms of chromium mutagenesis, should enhance our ability to evaluate the risks associated with human exposure to the environmental hazard, and perhaps suggest methods for intervention and prevention of adverse health effects of exposure.","MOLECULAR MECHANISMS OF CHROMIUM MUTAGENESIS Abs: Chromium has been identified as a ""primary hazardous substance"" at a large proportion of the Superfund Hazardous Waste Sites. Epidemiological studies have linked the exposure to chromium compounds in the work place to increased risk for development of lung cancer. Furthermore, certain forms of chromium have been shown to be carcinogenic in animals and mutagenic in bacteria and mammalian cell systems. Although the process of carcinogenesis is complex, it is clear that mutagenic activation of proto-oncogenes plays an important role. The purpose of the research proposed here is to understand the mechanisms by which chromium causes mutations in mammalian cells and to provide a link between the mutagenic and carcinogenic activities of chromium. We are using shuttle vectors in cultured mammalian cells and yeast to identify premutagenic DNA damage induced by chromium compounds and to determine the mutagenic specificity of this damage. We are also using a mammalian in vitro DNA replication system to investigate how the cellular DNA replication apparatus responds to chromium-induced template damage and whether DNA replication fidelity is affected by direct effects of chromium on DNA replication factors. In addition, we are seeking a link between chromium mutagenesis and carcinogenesis by using transgenic mice to examine the mutagenic effects of inhaled calcium chromate dust in the lung - the target organ for chromium carcinogenesis. The focus of this work will be to understand the role that biotransformation of chromium within the cell plays in the mutagenic activation of the compound. Apparently, chromium enters the cells as Cr(VI) where it can be reduced to reactive species Cr(V), Cr(VI) and Cr(III). Although a number of cellular macromolecules have been implicated in these transformations, it appears that intracellular glutathione may play a key role in chromium reduction and mutagenesis. We propose to test the following hypothesis: The intracellular reduction of chromium by glutathione is a major pathway for the generation of reactive intermediates that are responsible for chromium mutagenesis in the intact cell and for chromium carcinogenesis in animals. By comparing the spectra of mutations induced in a mutagenesis target gene by chromium compounds when plasmid DNA is treated in vitro and replicated in yeast or mammalian cells, when yeast or mammalian cells that contain plasmid are treated with chromium, and in the transgene in the lungs of mice following chromium inhalation, we hope to identify the types of premutagenic DNA damage that are important in chromium mutagenesis and determine how the mutagenic specificity is determined by the specific pathway for chromium reduction in the cell. An increased understanding of the mechanisms of chromium mutagenesis, should enhance our ability to evaluate the risks associated with human exposure to the environmental hazard, and perhaps suggest methods for intervention and prevention of adverse health effects of exposure."
1237595,Schlesinger 2000,O3 AND MODULATING CR TOXICITY AND THE LUNG,"Most studies of occupationally relevant chemical hazards have involved use of single contaminants, so the biological and safety implications from inhalation of realistic mixtures have commonly been ignored in evaluations related to worker health and safety. In this regard, chromium (Cr) is released with ozone (O3) during welding, and a major health hazard from inhalation exposure to Cr-containing materials is lung cancer; this is likely due largely to the insoluble Cr species in the fumes. However, the contribution from other co-inhalants in modulating Cr-initiated responses is not clear. Co-contaminants may change the pulmonary environment producing conditions which could enhance the formation and survival of Cr- initiated tumors. For example, it has been demonstrated that simultaneously-inhaled O3 increases the pulmonary retention of inhaled insoluble Cr particles; this could be part of a scenario which would ultimately give rise to conditions within the lungs conductive to the formation and survival of Cr-initiated neoplasia. This proposal investigates other mechanisms underlying the elevated lung cancer incidence in welders exposed welding fumes containing both Cr and O3. It is hypothesized that the carcinogenic potential of insoluble Cr(VI) in the lungs of hosts inhaling the Cr/O3 mixture is greater than that in hosts inhaling the Cr alone due to O3-mediated increases in the lung tissue burdens of Cr(VI) and/or augmentation of one or more of the documented genetic/epigenetic mechanisms associated with Cr-induced conversion of normal cells to transformed types (i.e., an enhancement in level of DNA damage, chromosomal aberrations, and/or induced increases in the activity of cell kinases known to regulate the expression of nascent oncogenes) arising from the effects of O3 upon mechanisms utilized for the intracellular of insoluble Cf(VI) particles. The project involves exposure of rats to atmospheres containing carcinogenic Cr(VI), namely calcium chromate, alone and in combination with O3. This study will improve our understanding of the mechanisms underlying the interaction between Cr and O3 in the lungs and the role which mixtures of air contaminants may play in pulmonary disease pathogenesis following exposure to realistic mixed atmospheres of occupational relevance.","O3 AND MODULATING CR TOXICITY AND THE LUNG Abs: Most studies of occupationally relevant chemical hazards have involved use of single contaminants, so the biological and safety implications from inhalation of realistic mixtures have commonly been ignored in evaluations related to worker health and safety. In this regard, chromium (Cr) is released with ozone (O3) during welding, and a major health hazard from inhalation exposure to Cr-containing materials is lung cancer; this is likely due largely to the insoluble Cr species in the fumes. However, the contribution from other co-inhalants in modulating Cr-initiated responses is not clear. Co-contaminants may change the pulmonary environment producing conditions which could enhance the formation and survival of Cr- initiated tumors. For example, it has been demonstrated that simultaneously-inhaled O3 increases the pulmonary retention of inhaled insoluble Cr particles; this could be part of a scenario which would ultimately give rise to conditions within the lungs conductive to the formation and survival of Cr-initiated neoplasia. This proposal investigates other mechanisms underlying the elevated lung cancer incidence in welders exposed welding fumes containing both Cr and O3. It is hypothesized that the carcinogenic potential of insoluble Cr(VI) in the lungs of hosts inhaling the Cr/O3 mixture is greater than that in hosts inhaling the Cr alone due to O3-mediated increases in the lung tissue burdens of Cr(VI) and/or augmentation of one or more of the documented genetic/epigenetic mechanisms associated with Cr-induced conversion of normal cells to transformed types (i.e., an enhancement in level of DNA damage, chromosomal aberrations, and/or induced increases in the activity of cell kinases known to regulate the expression of nascent oncogenes) arising from the effects of O3 upon mechanisms utilized for the intracellular of insoluble Cf(VI) particles. The project involves exposure of rats to atmospheres containing carcinogenic Cr(VI), namely calcium chromate, alone and in combination with O3. This study will improve our understanding of the mechanisms underlying the interaction between Cr and O3 in the lungs and the role which mixtures of air contaminants may play in pulmonary disease pathogenesis following exposure to realistic mixed atmospheres of occupational relevance."
1237594,Dixon 2000,MOLECULAR MECHANISMS OF CHROMIUM MUTAGENESIS,"Chromium has been identified as a ""primary hazardous substance"" at a large proportion of the Superfund Hazardous Waste Sites. Epidemiological studies have linked the exposure to chromium compounds in the work place to increased risk for development of lung cancer. Furthermore, certain forms of chromium have been shown to be carcinogenic in animals and mutagenic in bacteria and mammalian cell systems. Although the process of carcinogenesis is complex, it is clear that mutagenic activation of proto-oncogenes plays an important role. The purpose of the research proposed here is to understand the mechanisms by which chromium causes mutations in mammalian cells and to provide a link between the mutagenic and carcinogenic activities of chromium. We are using shuttle vectors in cultured mammalian cells and yeast to identify premutagenic DNA damage induced by chromium compounds and to determine the mutagenic specificity of this damage. We are also using a mammalian in vitro DNA replication system to investigate how the cellular DNA replication apparatus responds to chromium-induced template damage and whether DNA replication fidelity is affected by direct effects of chromium on DNA replication factors. In addition, we are seeking a link between chromium mutagenesis and carcinogenesis by using transgenic mice to examine the mutagenic effects of inhaled calcium chromate dust in the lung - the target organ for chromium carcinogenesis. The focus of this work will be to understand the role that biotransformation of chromium within the cell plays in the mutagenic activation of the compound. Apparently, chromium enters the cells as Cr(VI) where it can be reduced to reactive species Cr(V), Cr(VI) and Cr(III). Although a number of cellular macromolecules have been implicated in these transformations, it appears that intracellular glutathione may play a key role in chromium reduction and mutagenesis. We propose to test the following hypothesis: The intracellular reduction of chromium by glutathione is a major pathway for the generation of reactive intermediates that are responsible for chromium mutagenesis in the intact cell and for chromium carcinogenesis in animals. By comparing the spectra of mutations induced in a mutagenesis target gene by chromium compounds when plasmid DNA is treated in vitro and replicated in yeast or mammalian cells, when yeast or mammalian cells that contain plasmid are treated with chromium, and in the transgene in the lungs of mice following chromium inhalation, we hope to identify the types of premutagenic DNA damage that are important in chromium mutagenesis and determine how the mutagenic specificity is determined by the specific pathway for chromium reduction in the cell. An increased understanding of the mechanisms of chromium mutagenesis, should enhance our ability to evaluate the risks associated with human exposure to the environmental hazard, and perhaps suggest methods for intervention and prevention of adverse health effects of exposure.","MOLECULAR MECHANISMS OF CHROMIUM MUTAGENESIS Abs: Chromium has been identified as a ""primary hazardous substance"" at a large proportion of the Superfund Hazardous Waste Sites. Epidemiological studies have linked the exposure to chromium compounds in the work place to increased risk for development of lung cancer. Furthermore, certain forms of chromium have been shown to be carcinogenic in animals and mutagenic in bacteria and mammalian cell systems. Although the process of carcinogenesis is complex, it is clear that mutagenic activation of proto-oncogenes plays an important role. The purpose of the research proposed here is to understand the mechanisms by which chromium causes mutations in mammalian cells and to provide a link between the mutagenic and carcinogenic activities of chromium. We are using shuttle vectors in cultured mammalian cells and yeast to identify premutagenic DNA damage induced by chromium compounds and to determine the mutagenic specificity of this damage. We are also using a mammalian in vitro DNA replication system to investigate how the cellular DNA replication apparatus responds to chromium-induced template damage and whether DNA replication fidelity is affected by direct effects of chromium on DNA replication factors. In addition, we are seeking a link between chromium mutagenesis and carcinogenesis by using transgenic mice to examine the mutagenic effects of inhaled calcium chromate dust in the lung - the target organ for chromium carcinogenesis. The focus of this work will be to understand the role that biotransformation of chromium within the cell plays in the mutagenic activation of the compound. Apparently, chromium enters the cells as Cr(VI) where it can be reduced to reactive species Cr(V), Cr(VI) and Cr(III). Although a number of cellular macromolecules have been implicated in these transformations, it appears that intracellular glutathione may play a key role in chromium reduction and mutagenesis. We propose to test the following hypothesis: The intracellular reduction of chromium by glutathione is a major pathway for the generation of reactive intermediates that are responsible for chromium mutagenesis in the intact cell and for chromium carcinogenesis in animals. By comparing the spectra of mutations induced in a mutagenesis target gene by chromium compounds when plasmid DNA is treated in vitro and replicated in yeast or mammalian cells, when yeast or mammalian cells that contain plasmid are treated with chromium, and in the transgene in the lungs of mice following chromium inhalation, we hope to identify the types of premutagenic DNA damage that are important in chromium mutagenesis and determine how the mutagenic specificity is determined by the specific pathway for chromium reduction in the cell. An increased understanding of the mechanisms of chromium mutagenesis, should enhance our ability to evaluate the risks associated with human exposure to the environmental hazard, and perhaps suggest methods for intervention and prevention of adverse health effects of exposure."
1237593,Zelikoff 2001,O3 AND MODULATING CR TOXICITY AND THE LUNG,"Most studies of occupationally relevant chemical hazards have involved use of single contaminants, so the biological and safety implications from inhalation of realistic mixtures have commonly been ignored in evaluations related to worker health and safety. In this regard, chromium (Cr) is released with ozone (O3) during welding, and a major health hazard from inhalation exposure to Cr-containing materials is lung cancer; this is likely due largely to the insoluble Cr species in the fumes. However, the contribution from other co-inhalants in modulating Cr-initiated responses is not clear. Co-contaminants may change the pulmonary environment producing conditions which could enhance the formation and survival of Cr- initiated tumors. For example, it has been demonstrated that simultaneously-inhaled O3 increases the pulmonary retention of inhaled insoluble Cr particles; this could be part of a scenario which would ultimately give rise to conditions within the lungs conductive to the formation and survival of Cr-initiated neoplasia. This proposal investigates other mechanisms underlying the elevated lung cancer incidence in welders exposed welding fumes containing both Cr and O3. It is hypothesized that the carcinogenic potential of insoluble Cr(VI) in the lungs of hosts inhaling the Cr/O3 mixture is greater than that in hosts inhaling the Cr alone due to O3-mediated increases in the lung tissue burdens of Cr(VI) and/or augmentation of one or more of the documented genetic/epigenetic mechanisms associated with Cr-induced conversion of normal cells to transformed types (i.e., an enhancement in level of DNA damage, chromosomal aberrations, and/or induced increases in the activity of cell kinases known to regulate the expression of nascent oncogenes) arising from the effects of O3 upon mechanisms utilized for the intracellular of insoluble Cf(VI) particles. The project involves exposure of rats to atmospheres containing carcinogenic Cr(VI), namely calcium chromate, alone and in combination with O3. This study will improve our understanding of the mechanisms underlying the interaction between Cr and O3 in the lungs and the role which mixtures of air contaminants may play in pulmonary disease pathogenesis following exposure to realistic mixed atmospheres of occupational relevance.","O3 AND MODULATING CR TOXICITY AND THE LUNG Abs: Most studies of occupationally relevant chemical hazards have involved use of single contaminants, so the biological and safety implications from inhalation of realistic mixtures have commonly been ignored in evaluations related to worker health and safety. In this regard, chromium (Cr) is released with ozone (O3) during welding, and a major health hazard from inhalation exposure to Cr-containing materials is lung cancer; this is likely due largely to the insoluble Cr species in the fumes. However, the contribution from other co-inhalants in modulating Cr-initiated responses is not clear. Co-contaminants may change the pulmonary environment producing conditions which could enhance the formation and survival of Cr- initiated tumors. For example, it has been demonstrated that simultaneously-inhaled O3 increases the pulmonary retention of inhaled insoluble Cr particles; this could be part of a scenario which would ultimately give rise to conditions within the lungs conductive to the formation and survival of Cr-initiated neoplasia. This proposal investigates other mechanisms underlying the elevated lung cancer incidence in welders exposed welding fumes containing both Cr and O3. It is hypothesized that the carcinogenic potential of insoluble Cr(VI) in the lungs of hosts inhaling the Cr/O3 mixture is greater than that in hosts inhaling the Cr alone due to O3-mediated increases in the lung tissue burdens of Cr(VI) and/or augmentation of one or more of the documented genetic/epigenetic mechanisms associated with Cr-induced conversion of normal cells to transformed types (i.e., an enhancement in level of DNA damage, chromosomal aberrations, and/or induced increases in the activity of cell kinases known to regulate the expression of nascent oncogenes) arising from the effects of O3 upon mechanisms utilized for the intracellular of insoluble Cf(VI) particles. The project involves exposure of rats to atmospheres containing carcinogenic Cr(VI), namely calcium chromate, alone and in combination with O3. This study will improve our understanding of the mechanisms underlying the interaction between Cr and O3 in the lungs and the role which mixtures of air contaminants may play in pulmonary disease pathogenesis following exposure to realistic mixed atmospheres of occupational relevance."
1237592,Stearns 2007,Uptake and Mutagenicity of Moderately Soluble Hexavalent Chromium,"DESCRIPTION (provided by applicant): Hexavalent chromium (Cr(VI)) is a known human lung carcinogen. Millions of workers are exposed to Cr(VI) worldwide. The most recent paradigm proposes that the chromate compounds that are moderately water-soluble are more carcinogenic than the chromates that are either insoluble or water-soluble; however, it is not understood why this is so. Most of the data on how chromium damages DNA and causes DNA mutations has come from either the insoluble chromates or the water soluble chromates, not from the moderately soluble chromates that may be the most carcinogenic. The moderately soluble chromates are zinc chromate, strontium chromate and calcium chromate. Several crucial pieces of information are lacking regarding the activity of these moderately soluble chromates. No mutagenicity studies have been carried out with these compounds in human lung epithelial cells, which are the target cells for tumor formation. The types of mutations that these compounds cause have not been characterized in any cell line. The relative mutagenic potency of these chromates is not known. The extent to which these compounds dissolve outside of cells or enter cells as particulates is not known. The involvement of the zinc, strontium and calcium counterions in chromate toxicity is not known. The goals of the current proposal are to explain (1) how the moderately soluble Cr(VI) compounds enter cells and (2) if the mutations caused by the moderately soluble chromates differ from those caused by the soluble and insoluble chromates. The first aim of this proposal will apply the techniques of inductively coupled plasma mass spectrometry, laser scanning confocal microscopy, transmission electron microscopy, and scanning electron microscopy to determine how the moderately soluble chromates enter cells. The second aim of this proposal will measure and characterize mutations at the hypoxanthine (guanine) phosphoribosyl transferase (hprt) locus caused by the moderately soluble chromates in human lung epithelial cells and will compare mutation frequency and identity with mutations caused by the soluble and insoluble chromates. Data from these experiments will determine the relative mutagenic potency of these chromates, and will give insight into mechanisms of action, i.e., involvement of counterion and possible DNA lesions responsible for the mutations. Data from this proposal will provide mode of action information that will be necessary for thorough human risk assessment. The purpose of this work is to determine how chromium(VI) causes cancer. The goals of this proposal are to explain (1) how the moderately soluble chromium(VI) compounds enter cells and (2) if the mutations caused by the moderately soluble chromates differ from those caused by the less carcinogenic soluble and insoluble chromates. Understanding the mode of action of these chromates will provide a foundation for human risk assessment.","Uptake and Mutagenicity of Moderately Soluble Hexavalent Chromium Abs: DESCRIPTION (provided by applicant): Hexavalent chromium (Cr(VI)) is a known human lung carcinogen. Millions of workers are exposed to Cr(VI) worldwide. The most recent paradigm proposes that the chromate compounds that are moderately water-soluble are more carcinogenic than the chromates that are either insoluble or water-soluble; however, it is not understood why this is so. Most of the data on how chromium damages DNA and causes DNA mutations has come from either the insoluble chromates or the water soluble chromates, not from the moderately soluble chromates that may be the most carcinogenic. The moderately soluble chromates are zinc chromate, strontium chromate and calcium chromate. Several crucial pieces of information are lacking regarding the activity of these moderately soluble chromates. No mutagenicity studies have been carried out with these compounds in human lung epithelial cells, which are the target cells for tumor formation. The types of mutations that these compounds cause have not been characterized in any cell line. The relative mutagenic potency of these chromates is not known. The extent to which these compounds dissolve outside of cells or enter cells as particulates is not known. The involvement of the zinc, strontium and calcium counterions in chromate toxicity is not known. The goals of the current proposal are to explain (1) how the moderately soluble Cr(VI) compounds enter cells and (2) if the mutations caused by the moderately soluble chromates differ from those caused by the soluble and insoluble chromates. The first aim of this proposal will apply the techniques of inductively coupled plasma mass spectrometry, laser scanning confocal microscopy, transmission electron microscopy, and scanning electron microscopy to determine how the moderately soluble chromates enter cells. The second aim of this proposal will measure and characterize mutations at the hypoxanthine (guanine) phosphoribosyl transferase (hprt) locus caused by the moderately soluble chromates in human lung epithelial cells and will compare mutation frequency and identity with mutations caused by the soluble and insoluble chromates. Data from these experiments will determine the relative mutagenic potency of these chromates, and will give insight into mechanisms of action, i.e., involvement of counterion and possible DNA lesions responsible for the mutations. Data from this proposal will provide mode of action information that will be necessary for thorough human risk assessment. The purpose of this work is to determine how chromium(VI) causes cancer. The goals of this proposal are to explain (1) how the moderately soluble chromium(VI) compounds enter cells and (2) if the mutations caused by the moderately soluble chromates differ from those caused by the less carcinogenic soluble and insoluble chromates. Understanding the mode of action of these chromates will provide a foundation for human risk assessment."
1237591,Stearns 2008,Uptake and Mutagenicity of Moderately Soluble Hexavalent Chromium,"DESCRIPTION (provided by applicant): Hexavalent chromium (Cr(VI)) is a known human lung carcinogen. Millions of workers are exposed to Cr(VI) worldwide. The most recent paradigm proposes that the chromate compounds that are moderately water-soluble are more carcinogenic than the chromates that are either insoluble or water-soluble; however, it is not understood why this is so. Most of the data on how chromium damages DNA and causes DNA mutations has come from either the insoluble chromates or the water soluble chromates, not from the moderately soluble chromates that may be the most carcinogenic. The moderately soluble chromates are zinc chromate, strontium chromate and calcium chromate. Several crucial pieces of information are lacking regarding the activity of these moderately soluble chromates. No mutagenicity studies have been carried out with these compounds in human lung epithelial cells, which are the target cells for tumor formation. The types of mutations that these compounds cause have not been characterized in any cell line. The relative mutagenic potency of these chromates is not known. The extent to which these compounds dissolve outside of cells or enter cells as particulates is not known. The involvement of the zinc, strontium and calcium counterions in chromate toxicity is not known. The goals of the current proposal are to explain (1) how the moderately soluble Cr(VI) compounds enter cells and (2) if the mutations caused by the moderately soluble chromates differ from those caused by the soluble and insoluble chromates. The first aim of this proposal will apply the techniques of inductively coupled plasma mass spectrometry, laser scanning confocal microscopy, transmission electron microscopy, and scanning electron microscopy to determine how the moderately soluble chromates enter cells. The second aim of this proposal will measure and characterize mutations at the hypoxanthine (guanine) phosphoribosyl transferase (hprt) locus caused by the moderately soluble chromates in human lung epithelial cells and will compare mutation frequency and identity with mutations caused by the soluble and insoluble chromates. Data from these experiments will determine the relative mutagenic potency of these chromates, and will give insight into mechanisms of action, i.e., involvement of counterion and possible DNA lesions responsible for the mutations. Data from this proposal will provide mode of action information that will be necessary for thorough human risk assessment. The purpose of this work is to determine how chromium(VI) causes cancer. The goals of this proposal are to explain (1) how the moderately soluble chromium(VI) compounds enter cells and (2) if the mutations caused by the moderately soluble chromates differ from those caused by the less carcinogenic soluble and insoluble chromates. Understanding the mode of action of these chromates will provide a foundation for human risk assessment.","Uptake and Mutagenicity of Moderately Soluble Hexavalent Chromium Abs: DESCRIPTION (provided by applicant): Hexavalent chromium (Cr(VI)) is a known human lung carcinogen. Millions of workers are exposed to Cr(VI) worldwide. The most recent paradigm proposes that the chromate compounds that are moderately water-soluble are more carcinogenic than the chromates that are either insoluble or water-soluble; however, it is not understood why this is so. Most of the data on how chromium damages DNA and causes DNA mutations has come from either the insoluble chromates or the water soluble chromates, not from the moderately soluble chromates that may be the most carcinogenic. The moderately soluble chromates are zinc chromate, strontium chromate and calcium chromate. Several crucial pieces of information are lacking regarding the activity of these moderately soluble chromates. No mutagenicity studies have been carried out with these compounds in human lung epithelial cells, which are the target cells for tumor formation. The types of mutations that these compounds cause have not been characterized in any cell line. The relative mutagenic potency of these chromates is not known. The extent to which these compounds dissolve outside of cells or enter cells as particulates is not known. The involvement of the zinc, strontium and calcium counterions in chromate toxicity is not known. The goals of the current proposal are to explain (1) how the moderately soluble Cr(VI) compounds enter cells and (2) if the mutations caused by the moderately soluble chromates differ from those caused by the soluble and insoluble chromates. The first aim of this proposal will apply the techniques of inductively coupled plasma mass spectrometry, laser scanning confocal microscopy, transmission electron microscopy, and scanning electron microscopy to determine how the moderately soluble chromates enter cells. The second aim of this proposal will measure and characterize mutations at the hypoxanthine (guanine) phosphoribosyl transferase (hprt) locus caused by the moderately soluble chromates in human lung epithelial cells and will compare mutation frequency and identity with mutations caused by the soluble and insoluble chromates. Data from these experiments will determine the relative mutagenic potency of these chromates, and will give insight into mechanisms of action, i.e., involvement of counterion and possible DNA lesions responsible for the mutations. Data from this proposal will provide mode of action information that will be necessary for thorough human risk assessment. The purpose of this work is to determine how chromium(VI) causes cancer. The goals of this proposal are to explain (1) how the moderately soluble chromium(VI) compounds enter cells and (2) if the mutations caused by the moderately soluble chromates differ from those caused by the less carcinogenic soluble and insoluble chromates. Understanding the mode of action of these chromates will provide a foundation for human risk assessment."
1237586,Cuesta et al. 1998,"Rapid determination of chemical oxygen demand by a semi-automated method based on microwave sample digestion, chromium(VI) organic solvent extraction and flame atomic absorption spectrometry","BIOSIS COPYRIGHT: BIOL ABS. In the present work, a new flow injection analysis (FIA) manifold for the rapid determination of chemical oxygen demand is presented and evaluated. The FIA manifold combines sample digestion by means of an oxidant solution (i.e., potassium dichromate and mercury sulfate) and an acid solution (sulfuric acid and silver sulfate) in a domestic microwave oven with the liquid-liquid extraction of Cr(VI) with tributyl phosphate (TBP). Finally, the remaining (non-reduced) Cr(VI) is determined in the organic phase by atomic absorption spectrometry. The digestion of the organic matter is carried out in the stopped-flow mode. Potassium hydrogenphthalate has been used for optimization of the method and as a standard to check its performance. The optimized conditions (oxidation) are: digestion time, 7 min; acid concentration, 67% (v/v). The optimized conditions for the extraction of the remaining Cr(VI) are: acid concentration,30% (v/v); TBP, 1 ml. The proposed method has been","Rapid determination of chemical oxygen demand by a semi-automated method based on microwave sample digestion, chromium(VI) organic solvent extraction and flame atomic absorption spectrometry Abs: BIOSIS COPYRIGHT: BIOL ABS. In the present work, a new flow injection analysis (FIA) manifold for the rapid determination of chemical oxygen demand is presented and evaluated. The FIA manifold combines sample digestion by means of an oxidant solution (i.e., potassium dichromate and mercury sulfate) and an acid solution (sulfuric acid and silver sulfate) in a domestic microwave oven with the liquid-liquid extraction of Cr(VI) with tributyl phosphate (TBP). Finally, the remaining (non-reduced) Cr(VI) is determined in the organic phase by atomic absorption spectrometry. The digestion of the organic matter is carried out in the stopped-flow mode. Potassium hydrogenphthalate has been used for optimization of the method and as a standard to check its performance. The optimized conditions (oxidation) are: digestion time, 7 min; acid concentration, 67% (v/v). The optimized conditions for the extraction of the remaining Cr(VI) are: acid concentration,30% (v/v); TBP, 1 ml. The proposed method has been"
1237585,Krassoi et al. 1997,Larval abnormalities in doughboy scallops Chlamys (Mimachlamys) asperrima L. in response to test conditions and six reference toxicants,"BIOSIS COPYRIGHT: BIOL ABS. Optimum test conditions were established for a 48 h larval abnormality test using the doughboy scallop Chlamys (Mimachlamys) asperrima L. The optimal test conditions for the development of fertilised eggs to 48 h D-veliger (prodissoconch I) stage were: temperature of 18? C, salinity of 32-34 , larval density of 5-30, egg:spermatozoa ratio of 1:200, light intensity of 1000 Lux, and photoperiod of 16:8 to 12:12 h light:dark. C. asperrima fertilised eggs were exposed to potassium dichromate, zinc sulfate, cadmium chloride, copper sulfate, sodium dodecyl sulfate (SDS) and 4-chlorophenol (4-CP), and were then examined for development through to the 48 h D-veliger stage. The respective concentrations that caused 50% larval abnormalities (EC50), no observed effect and lowest observed effect concentrations, respectively, were 1350, 530 and 950 mug Cr/L; 45, 5 and 13 mug Zn/L; 295, 50 and 100 mug Cd/L; 4.5, 2 and 3 mug Cu/L; 1.0, 0.5 and 0.7 mg SDS/L; and 19.0, 3.0 and 5.0","Larval abnormalities in doughboy scallops Chlamys (Mimachlamys) asperrima L. in response to test conditions and six reference toxicants Abs: BIOSIS COPYRIGHT: BIOL ABS. Optimum test conditions were established for a 48 h larval abnormality test using the doughboy scallop Chlamys (Mimachlamys) asperrima L. The optimal test conditions for the development of fertilised eggs to 48 h D-veliger (prodissoconch I) stage were: temperature of 18? C, salinity of 32-34 , larval density of 5-30, egg:spermatozoa ratio of 1:200, light intensity of 1000 Lux, and photoperiod of 16:8 to 12:12 h light:dark. C. asperrima fertilised eggs were exposed to potassium dichromate, zinc sulfate, cadmium chloride, copper sulfate, sodium dodecyl sulfate (SDS) and 4-chlorophenol (4-CP), and were then examined for development through to the 48 h D-veliger stage. The respective concentrations that caused 50% larval abnormalities (EC50), no observed effect and lowest observed effect concentrations, respectively, were 1350, 530 and 950 mug Cr/L; 45, 5 and 13 mug Zn/L; 295, 50 and 100 mug Cd/L; 4.5, 2 and 3 mug Cu/L; 1.0, 0.5 and 0.7 mg SDS/L; and 19.0, 3.0 and 5.0"
1237577,Itow et al. 1998,Development abnormalities in horseshoe crab embryos caused by exposure too heavy metals,"BIOSIS COPYRIGHT: BIOL ABS. We examined the effects of heavy metals on the development of horseshoe crabs using bioassays in which embryos at different stages were exposed either continuously or for 24 h. Abnormalities included segment-defective embryos, double embryos, embryos with abnormal eye areas, and no-posterior embryos. In terms of their ability to affect normal development, the pollutants are ranked as follows: Hg \ organotin Crth a high frequency of abnormal eye embryos and Hg with segment-defective embryos. The specific cause of segment-defective malformations by Hg was investigated by using SH inhibitors and cytochalasin B, an inhibitor of microfilaments. These inhibitors induced Hg-type segment-defective embryos; thus, Hg may also act by inhibiting SH-SS exchange and blocking morphogenetic movements. Horseshoe crab embryos from Delaware Bay and Sandy Hook Bay, New Jersey, were examined for developmental abnormalities. Malformed embryos were extremely rare (<0.6%) at five beac","Development abnormalities in horseshoe crab embryos caused by exposure too heavy metals Abs: BIOSIS COPYRIGHT: BIOL ABS. We examined the effects of heavy metals on the development of horseshoe crabs using bioassays in which embryos at different stages were exposed either continuously or for 24 h. Abnormalities included segment-defective embryos, double embryos, embryos with abnormal eye areas, and no-posterior embryos. In terms of their ability to affect normal development, the pollutants are ranked as follows: Hg \ organotin Crth a high frequency of abnormal eye embryos and Hg with segment-defective embryos. The specific cause of segment-defective malformations by Hg was investigated by using SH inhibitors and cytochalasin B, an inhibitor of microfilaments. These inhibitors induced Hg-type segment-defective embryos; thus, Hg may also act by inhibiting SH-SS exchange and blocking morphogenetic movements. Horseshoe crab embryos from Delaware Bay and Sandy Hook Bay, New Jersey, were examined for developmental abnormalities. Malformed embryos were extremely rare (<0.6%) at five beac"
1237574,Karcher 1998,Recent trends and developments in the EU in the environmental control and management of chemicals,"BIOSIS COPYRIGHT: BIOL ABS. In the further development and implementation of European legislation on chemicals and related products the following aspects and trends can be identified: (1) refinement and adaptation of existing legislation and guidelines to technical progress (including extension of testing and risk assessment strategies), (2) preparation and implementation of new directives and regulations, (3) increasing application and further development of screening methods and model approaches, and (4) global harmonization of hazard and risk assessment criteria and procedures in the frame of the International Forum on Chemical Safety (chapter 19 of Agenda 21). The increasing use of evaluation and screening models can be illustrated by the further development and application of specific models such as EUSES and EASE to predict effect and exposure data. On the effects assessment side, models are available or under development to predict the phototoxicity and potential endocrine disruptors (estr","Recent trends and developments in the EU in the environmental control and management of chemicals Abs: BIOSIS COPYRIGHT: BIOL ABS. In the further development and implementation of European legislation on chemicals and related products the following aspects and trends can be identified: (1) refinement and adaptation of existing legislation and guidelines to technical progress (including extension of testing and risk assessment strategies), (2) preparation and implementation of new directives and regulations, (3) increasing application and further development of screening methods and model approaches, and (4) global harmonization of hazard and risk assessment criteria and procedures in the frame of the International Forum on Chemical Safety (chapter 19 of Agenda 21). The increasing use of evaluation and screening models can be illustrated by the further development and application of specific models such as EUSES and EASE to predict effect and exposure data. On the effects assessment side, models are available or under development to predict the phototoxicity and potential endocrine disruptors (estr"
1237570,Mayer et al. 1998,Influence of growth conditions on the results obtained in algal toxicity tests,"BIOSIS COPYRIGHT: BIOL ABS. The influence of test conditions on results from algal growth inhibition tests was investigated for the toxicants atrazine, 3,4-dichloroaniline, 3,5-dichlorophenol, and potassium dichromate. Emphasis was put on the following four main factors: light, temperature, nitrogen source, and pH. The green alga Selenastrum capricornutum was grown in batch cultures, and the toxic response was measured as reduction in average growth rate, relative to controls. Multifactor experiments were carried out to investigate the effects of the above four factors as well as the interactions between them: light intensity (44 and 198 muE/m2/s), temperature (16 and 26? C), nitrogen source (NH4+ and NO3-), and pH of the medium (7.5 and 8.6). Within the data set generated, the highest and lowest median effective concentration estimate differed by a factor of 3.8. The sensitivity of the test system to 3,4-dichloroaniline, potassium dichromate, and 3,5-dichlorophenol was less under light limitation","Influence of growth conditions on the results obtained in algal toxicity tests Abs: BIOSIS COPYRIGHT: BIOL ABS. The influence of test conditions on results from algal growth inhibition tests was investigated for the toxicants atrazine, 3,4-dichloroaniline, 3,5-dichlorophenol, and potassium dichromate. Emphasis was put on the following four main factors: light, temperature, nitrogen source, and pH. The green alga Selenastrum capricornutum was grown in batch cultures, and the toxic response was measured as reduction in average growth rate, relative to controls. Multifactor experiments were carried out to investigate the effects of the above four factors as well as the interactions between them: light intensity (44 and 198 muE/m2/s), temperature (16 and 26? C), nitrogen source (NH4+ and NO3-), and pH of the medium (7.5 and 8.6). Within the data set generated, the highest and lowest median effective concentration estimate differed by a factor of 3.8. The sensitivity of the test system to 3,4-dichloroaniline, potassium dichromate, and 3,5-dichlorophenol was less under light limitation"
1237563,Li et al. 1997,Carcinogens stimulate intrachromosomal homologous recombination at an endogenous locus in human diploid fibroblasts,"BIOSIS COPYRIGHT: BIOL ABS. Mitotic recombination is believed to play an important role in the development of many cancers. An improved system has been developed to detect reversion of an intragenic DNA duplication, as a model for intrachromosomal homologous recombination. The 'LNtd' strain of human fibroblasts, derived from a Lesch-Nyhan donor, produces no detectable hypoxanthine phosphoribosyltransferase (HPRT) activity due to a 13.7-kilobase-pair DNA insertion duplicating exons 2 and 3 of the HPRT locus. These cells are therefore sensitive to selection in HAT medium, against cells lacking functional HPRT enzyme. Clonal reversion to HAT resistance occurs spontaneously at 1-3-5/cell/generation, and can be induced by brief exposure to a variety of carcinogenic agents. Six known carcinogens, including two (diethylstilbestrol and nickel chloride) which were non-mutagenic in Salmonella by Ames HIS-reversion tests. showed dose-dependent induction of LNtd reversion by a maximum of 2.4- to 11-fold","Carcinogens stimulate intrachromosomal homologous recombination at an endogenous locus in human diploid fibroblasts Abs: BIOSIS COPYRIGHT: BIOL ABS. Mitotic recombination is believed to play an important role in the development of many cancers. An improved system has been developed to detect reversion of an intragenic DNA duplication, as a model for intrachromosomal homologous recombination. The 'LNtd' strain of human fibroblasts, derived from a Lesch-Nyhan donor, produces no detectable hypoxanthine phosphoribosyltransferase (HPRT) activity due to a 13.7-kilobase-pair DNA insertion duplicating exons 2 and 3 of the HPRT locus. These cells are therefore sensitive to selection in HAT medium, against cells lacking functional HPRT enzyme. Clonal reversion to HAT resistance occurs spontaneously at 1-3-5/cell/generation, and can be induced by brief exposure to a variety of carcinogenic agents. Six known carcinogens, including two (diethylstilbestrol and nickel chloride) which were non-mutagenic in Salmonella by Ames HIS-reversion tests. showed dose-dependent induction of LNtd reversion by a maximum of 2.4- to 11-fold"
1237561,Bakkum R S and  Oei 1998,PATCH TESTING IN CHILDREN WITH ATOPIC DERMATITIS,BIOSIS COPYRIGHT: BIOL ABS. RRM MEETING ABSTRACT HUMAN PREADOLESCENT FEMALE MALE PATIENT PRESCHOOL ATOPIC DERMATITIS PATCH TESTS EUROPEAN STANDARD SERIES OF ALLERGENS NICKEL SULFATE ALLERGEN COBALT CHLORIDE FRAGRANCE MIX POTASSIUM DICHROMATE NEOMYCIN PARAPHENYLENE DIAMINE EPOXY RESIN WOOL ALCOHOLS BALSAM OF PERU P-TERTIARY BUTYLPHENOLFORMALDEHYDE RESIN CARBA MIX KATHON CG QUATERNIUM-15 PARABENS ALLERGY METHODOLOGY PEDIATRICS INTEGUMENTARY SYSTEM DISEASE IMMUNE SYSTEM DISEASE GENETIC DISEASE DIAGNOSTIC METHOD,PATCH TESTING IN CHILDREN WITH ATOPIC DERMATITIS Abs: BIOSIS COPYRIGHT: BIOL ABS. RRM MEETING ABSTRACT HUMAN PREADOLESCENT FEMALE MALE PATIENT PRESCHOOL ATOPIC DERMATITIS PATCH TESTS EUROPEAN STANDARD SERIES OF ALLERGENS NICKEL SULFATE ALLERGEN COBALT CHLORIDE FRAGRANCE MIX POTASSIUM DICHROMATE NEOMYCIN PARAPHENYLENE DIAMINE EPOXY RESIN WOOL ALCOHOLS BALSAM OF PERU P-TERTIARY BUTYLPHENOLFORMALDEHYDE RESIN CARBA MIX KATHON CG QUATERNIUM-15 PARABENS ALLERGY METHODOLOGY PEDIATRICS INTEGUMENTARY SYSTEM DISEASE IMMUNE SYSTEM DISEASE GENETIC DISEASE DIAGNOSTIC METHOD
1237559,Lugovic and  Lipozencic 1997,Contact hypersensitivity in atopic dermatitis,"BIOSIS COPYRIGHT: BIOL ABS. From January 1990 to December 1994, a total of 84 patients (56 men and 28 women) with atopic dermatitis (AD) were referred to our Clinic for patch testing. The European standard series of allergens was applied to all subjects together with any additional series indicated in the case history, Sensitization to at least one of the allergens was found in 57.1% of individuals with AD. Positive reactions were more frequently determined in adults than in children with AD. Women and men were equally positive in epicutaneous testing. The commonest sensitizer was nickel sulfate (discriminative in 28.6%). Adult patients with atopic dermatitis significantly differed from patients with chronic urticaria or healthy controls in patch test positive results. Our findings suggest that allergic contact dermatitis is more common in patients with AD than generally assumed and that patch testing is a practicable and clinically worthwhile procedure for determining allergic contact dermatitis","Contact hypersensitivity in atopic dermatitis Abs: BIOSIS COPYRIGHT: BIOL ABS. From January 1990 to December 1994, a total of 84 patients (56 men and 28 women) with atopic dermatitis (AD) were referred to our Clinic for patch testing. The European standard series of allergens was applied to all subjects together with any additional series indicated in the case history, Sensitization to at least one of the allergens was found in 57.1% of individuals with AD. Positive reactions were more frequently determined in adults than in children with AD. Women and men were equally positive in epicutaneous testing. The commonest sensitizer was nickel sulfate (discriminative in 28.6%). Adult patients with atopic dermatitis significantly differed from patients with chronic urticaria or healthy controls in patch test positive results. Our findings suggest that allergic contact dermatitis is more common in patients with AD than generally assumed and that patch testing is a practicable and clinically worthwhile procedure for determining allergic contact dermatitis"
1237558,Dierickx 1998,Increased cytotoxic sensitivity of cultured FHM fish cells by simultaneous treatment with sodium dodecyl sulfate and buthionine sulfoximine,"BIOSIS COPYRIGHT: BIOL ABS. A previously described neutral red uptake inhibition assay on cultured fathead minnow (FHM) fish cells revealed a good correlation with fish toxicity data (Brandao et al., 1992) for a series of 50 test compounds, belonging to completely different chemical classes. The major drawback was the lower sensitivity of the cytotoxicity assay. Aiming at a higher sensitivity the assay was adapted by reducing the cell number, by a longer treatment period, and by simultaneous treatment with sodium dodecyl sulfate and buthionine sulfoximine (BSO). The fluorimetrically measured protein content was chosen as the endpoint. The endogenous glutathione (GSH) content was reduced by 54% of the test chemicals, confirming the importance of GSH in detoxification processes. Higher sensitivity was, at least partly, obtained by treating the FHM cells with BSO, reducing the GSH content to 22% of that in control cells. The cytotoxicity of the 50 chemicals was measured using the modified more sensit","Increased cytotoxic sensitivity of cultured FHM fish cells by simultaneous treatment with sodium dodecyl sulfate and buthionine sulfoximine Abs: BIOSIS COPYRIGHT: BIOL ABS. A previously described neutral red uptake inhibition assay on cultured fathead minnow (FHM) fish cells revealed a good correlation with fish toxicity data (Brandao et al., 1992) for a series of 50 test compounds, belonging to completely different chemical classes. The major drawback was the lower sensitivity of the cytotoxicity assay. Aiming at a higher sensitivity the assay was adapted by reducing the cell number, by a longer treatment period, and by simultaneous treatment with sodium dodecyl sulfate and buthionine sulfoximine (BSO). The fluorimetrically measured protein content was chosen as the endpoint. The endogenous glutathione (GSH) content was reduced by 54% of the test chemicals, confirming the importance of GSH in detoxification processes. Higher sensitivity was, at least partly, obtained by treating the FHM cells with BSO, reducing the GSH content to 22% of that in control cells. The cytotoxicity of the 50 chemicals was measured using the modified more sensit"
1237557,Baillet et al. 1998,Chromium precipitation by the acidophilic bacterium Thiobacillus ferrooxidans,"BIOSIS COPYRIGHT: BIOL ABS. Thiobacillus ferrooxidans tolerates Cr3+ up to 75 mM during growth on ferrous sulphate without modification of its bacterial activity (53 mug protein mM-1 Fe2+ oxidized). At pH 1.4 and in the presence of Cr2O3, a maximal uptake capacity of 509 mg.g-1 dry weight was obtained with biomass harvested in the middle of the exponential growth phase. Cr6+ uptake by T. ferrooxidans resulted in the precipitation of a chromium-rich compound on the surface bacterial cells, as observed by transmission electron microscopy.","Chromium precipitation by the acidophilic bacterium Thiobacillus ferrooxidans Abs: BIOSIS COPYRIGHT: BIOL ABS. Thiobacillus ferrooxidans tolerates Cr3+ up to 75 mM during growth on ferrous sulphate without modification of its bacterial activity (53 mug protein mM-1 Fe2+ oxidized). At pH 1.4 and in the presence of Cr2O3, a maximal uptake capacity of 509 mg.g-1 dry weight was obtained with biomass harvested in the middle of the exponential growth phase. Cr6+ uptake by T. ferrooxidans resulted in the precipitation of a chromium-rich compound on the surface bacterial cells, as observed by transmission electron microscopy."
1237556,Barnhart 1997,Chromium chemistry and implications for environmental fate and toxicity,"BIOSIS COPYRIGHT: BIOL ABS. The same chemical properties that make chromium such an important component of so many industrial and consumer products are the important factors controlling its environmental fate and toxicity. Although only about 15% of the chromium mined is used in the manufacture of chromium chemicals, the chemistry of chromium is important in nearly all applications. For instance, the 'stainless' nature of stainless steel is due to the chemical properties of the chromium oxides that form on the surface of the alloy. Similarly, the product protection afforded by chrome plating of metals, CCA treatment of wood, and chrome tanning of leather is; directly dependent on chromium chemistry. In all of these applications the most important chemical property is that under typical environmental and biological conditions of pH and oxidation-reduction potential, the most stable form of chromium is the trivalent oxide. This form has very low solubility and low reactivity resulting in low mobilit","Chromium chemistry and implications for environmental fate and toxicity Abs: BIOSIS COPYRIGHT: BIOL ABS. The same chemical properties that make chromium such an important component of so many industrial and consumer products are the important factors controlling its environmental fate and toxicity. Although only about 15% of the chromium mined is used in the manufacture of chromium chemicals, the chemistry of chromium is important in nearly all applications. For instance, the 'stainless' nature of stainless steel is due to the chemical properties of the chromium oxides that form on the surface of the alloy. Similarly, the product protection afforded by chrome plating of metals, CCA treatment of wood, and chrome tanning of leather is; directly dependent on chromium chemistry. In all of these applications the most important chemical property is that under typical environmental and biological conditions of pH and oxidation-reduction potential, the most stable form of chromium is the trivalent oxide. This form has very low solubility and low reactivity resulting in low mobilit"
1237554,Little et al. 1998,The participation of proliferative keratinocytes in the preimmune response to sensitizing agents,"BIOSIS COPYRIGHT: BIOL ABS. The aims of this study were to investigate whether keratinocytes are capable of playing a direct preimmune role in the pathophysiology of allergic contact dermatitis (ACD) and to examine to what extent the degree of differentiation might influence this. We measured the ability of sensitizing agents to up-regulate intercellular adhesion molecule 1 (ICAM-1) expression in cultured normal human keratinocytes (NHK) and in the transformed human keratinocyte HaCaT cell line. In proliferative HaCaT cells, following a 24 h exposure, nickel compounds, para-phenylenediamine (pPD) and 1-chloro-2,4-dinitrobenzene produced a concentration-dependent up-regulation of ICAM-1 expression without reducing cell viability while K2Cr2O7 led to ICAM-1 up-regulation at cytotoxic concentrations, and CrCl3 was without effect. In NHK, NiSO4 and pPD induced ICAM-1 expression to a significantly greater extent in proliferative cells than in differentiated cells, where involucrin expression was measur","The participation of proliferative keratinocytes in the preimmune response to sensitizing agents Abs: BIOSIS COPYRIGHT: BIOL ABS. The aims of this study were to investigate whether keratinocytes are capable of playing a direct preimmune role in the pathophysiology of allergic contact dermatitis (ACD) and to examine to what extent the degree of differentiation might influence this. We measured the ability of sensitizing agents to up-regulate intercellular adhesion molecule 1 (ICAM-1) expression in cultured normal human keratinocytes (NHK) and in the transformed human keratinocyte HaCaT cell line. In proliferative HaCaT cells, following a 24 h exposure, nickel compounds, para-phenylenediamine (pPD) and 1-chloro-2,4-dinitrobenzene produced a concentration-dependent up-regulation of ICAM-1 expression without reducing cell viability while K2Cr2O7 led to ICAM-1 up-regulation at cytotoxic concentrations, and CrCl3 was without effect. In NHK, NiSO4 and pPD induced ICAM-1 expression to a significantly greater extent in proliferative cells than in differentiated cells, where involucrin expression was measur"
1237552,Pantani et al. 1997,COMPARATIVE ACUTE TOXICITY OF SOME PESTICIDES METALS AND SURFACTANTS TO GAMMARUS ITALICUS GOEDM. AND ECHINOGAMMARUS TIBALDII PINK AND STOCK CRUSTACEA AMPHIPODA,BIOSIS COPYRIGHT: BIOL ABS. RRM RESEARCH ARTICLE GAMMARUS-ITALICUS ECHINOGAMMARUS-TIBALDII DAPHNIA-MAGNA PESTICIDES TOXICOLOGY FRESHWATER ECOLOGY AQUATIC ECOSYSTEMS METALS TOXIN SURFACTANTS,COMPARATIVE ACUTE TOXICITY OF SOME PESTICIDES METALS AND SURFACTANTS TO GAMMARUS ITALICUS GOEDM. AND ECHINOGAMMARUS TIBALDII PINK AND STOCK CRUSTACEA AMPHIPODA Abs: BIOSIS COPYRIGHT: BIOL ABS. RRM RESEARCH ARTICLE GAMMARUS-ITALICUS ECHINOGAMMARUS-TIBALDII DAPHNIA-MAGNA PESTICIDES TOXICOLOGY FRESHWATER ECOLOGY AQUATIC ECOSYSTEMS METALS TOXIN SURFACTANTS
1237551,Larrain et al. 1997,Evaluation of three larval instars of the Midge Chironomus petiolatus as bioassay tools using a computationally intensive statistical algorithm,"BIOSIS COPYRIGHT: BIOL ABS. Sensitivity to toxicants is a major criterion for selecting organisms for bioassay testing. If a sensitive species is also abundant and occupies a role as prey for many other species within a community, then the species become a valuable tool in environmental monitoring. These features apply to larval midge Chironomus petiolatus in freshwater environments of central Chile. The youngest larval instar is the most sensitive and presents the additional feature of lower survival within control arenas, making it more difficult to discern toxicant-related mortality from background mortality. In this work, we perform acute bioassays with the three larval stages of C. petiolatus and K2Cr2O7 as reference toxicant, with the goal of selecting a particular instar as the best bioassay tool using two criteria: sensitivity and background mortality. Sensitivity is evaluated through Monte Carlo estimation of LC50 and background mortality through bootstrap resampling, and a final Bioassay","Evaluation of three larval instars of the Midge Chironomus petiolatus as bioassay tools using a computationally intensive statistical algorithm Abs: BIOSIS COPYRIGHT: BIOL ABS. Sensitivity to toxicants is a major criterion for selecting organisms for bioassay testing. If a sensitive species is also abundant and occupies a role as prey for many other species within a community, then the species become a valuable tool in environmental monitoring. These features apply to larval midge Chironomus petiolatus in freshwater environments of central Chile. The youngest larval instar is the most sensitive and presents the additional feature of lower survival within control arenas, making it more difficult to discern toxicant-related mortality from background mortality. In this work, we perform acute bioassays with the three larval stages of C. petiolatus and K2Cr2O7 as reference toxicant, with the goal of selecting a particular instar as the best bioassay tool using two criteria: sensitivity and background mortality. Sensitivity is evaluated through Monte Carlo estimation of LC50 and background mortality through bootstrap resampling, and a final Bioassay"
1237548,Sacco et al. 1997,A transgenic mouse model for the detection of cellular stress induced by toxic inorganic compounds,"BIOSIS COPYRIGHT: BIOL ABS. Transgenic mice for genotoxicity testing have been developed, although no such models have been produced for the evaluation of toxic, nongenotoxic chemical compounds. We have developed a transgenic mouse model for the analysis of toxic inorganic compounds. We engineered a mouse lineage with the human growth hormone (hGH) gene under the control of the human hsp70 promoter, in which a plasma-detectable hGH response can be elicited by exposure to heat shock. In primary cell cultures from these mice, hGH release was observed following treatment with several toxic inorganics. Transgenic mice injected intraperitoneally with sodium arsenite, cadmium chloride, copper sulphate, or methylmercurium chloride showed significant hGH levels in plasma.","A transgenic mouse model for the detection of cellular stress induced by toxic inorganic compounds Abs: BIOSIS COPYRIGHT: BIOL ABS. Transgenic mice for genotoxicity testing have been developed, although no such models have been produced for the evaluation of toxic, nongenotoxic chemical compounds. We have developed a transgenic mouse model for the analysis of toxic inorganic compounds. We engineered a mouse lineage with the human growth hormone (hGH) gene under the control of the human hsp70 promoter, in which a plasma-detectable hGH response can be elicited by exposure to heat shock. In primary cell cultures from these mice, hGH release was observed following treatment with several toxic inorganics. Transgenic mice injected intraperitoneally with sodium arsenite, cadmium chloride, copper sulphate, or methylmercurium chloride showed significant hGH levels in plasma."
1237545,Reutter et al. 1997,In vitro model for contact sensitization: II. Induction of IL-1beta mRNA in human blood-derived dendritic cells by contact sensitizers,"BIOSIS COPYRIGHT: BIOL ABS. Epidermal mRNA for interleukin 1beta (IL-1beta) has been shown to be increased following exposure of mouse skin to sensitizing compounds. In addition, this early upregulation of IL-1beta was specific for contact sensitizers, while expression of IL-1beta was unaffected by irritants. Langerhans cells are the major source of IL-1beta within the epidermis in the induction phase of skin sensitization. Since the isolation of Langerhans cells from skin biopsies results only in low frequencies, we decid dendritic cells (DCs) generated from peripheral blood as Langerhans cell equivalents to investigate the ability of five contact sensitizers and one irritant to induce IL-1beta gene expression in vitro. For our studies we cultivated DCs in serum-free medium supplemented with granulocyte/macrophage-colony stimulation factor (GM-CSF) and interleukin 4 (IL-4). The DCs showed a typical dendritic morphology, a characteristic expression of surface markers and high stimulatory capacity f","In vitro model for contact sensitization: II. Induction of IL-1beta mRNA in human blood-derived dendritic cells by contact sensitizers Abs: BIOSIS COPYRIGHT: BIOL ABS. Epidermal mRNA for interleukin 1beta (IL-1beta) has been shown to be increased following exposure of mouse skin to sensitizing compounds. In addition, this early upregulation of IL-1beta was specific for contact sensitizers, while expression of IL-1beta was unaffected by irritants. Langerhans cells are the major source of IL-1beta within the epidermis in the induction phase of skin sensitization. Since the isolation of Langerhans cells from skin biopsies results only in low frequencies, we decid dendritic cells (DCs) generated from peripheral blood as Langerhans cell equivalents to investigate the ability of five contact sensitizers and one irritant to induce IL-1beta gene expression in vitro. For our studies we cultivated DCs in serum-free medium supplemented with granulocyte/macrophage-colony stimulation factor (GM-CSF) and interleukin 4 (IL-4). The DCs showed a typical dendritic morphology, a characteristic expression of surface markers and high stimulatory capacity f"
1237544,Thomulka et al. 1997,"Use of Vibrio harveyi in an aquatic bioluminescent toxicity test to assess the effects of metal toxicity: Treatment of sand and water-buffer, with and without EDTA","BIOSIS COPYRIGHT: BIOL ABS. This investigation evaluated the effects of sand and EDTA on the toxicity of 24 metallic salts on the bioluminescent bacterium Vibrio harveyi, Toxicity end points were reported as either median effective concentration (EC50) or effective concentration at 20%. Sand and EDTA individually and in sequential combination generally reduced toxicity of metals tested in this system. When comparing treatments of sand without EDTA and sand, some chemicals exhibited lower toxicity while others had increased toxicity. Each chemical appears to have its own unique characteric for toxicity when evaluated using the test conditions with this organism.","Use of Vibrio harveyi in an aquatic bioluminescent toxicity test to assess the effects of metal toxicity: Treatment of sand and water-buffer, with and without EDTA Abs: BIOSIS COPYRIGHT: BIOL ABS. This investigation evaluated the effects of sand and EDTA on the toxicity of 24 metallic salts on the bioluminescent bacterium Vibrio harveyi, Toxicity end points were reported as either median effective concentration (EC50) or effective concentration at 20%. Sand and EDTA individually and in sequential combination generally reduced toxicity of metals tested in this system. When comparing treatments of sand without EDTA and sand, some chemicals exhibited lower toxicity while others had increased toxicity. Each chemical appears to have its own unique characteric for toxicity when evaluated using the test conditions with this organism."
1237542,Lopez and  Moretton 1997,EFFECTS OF RIVER WATERS SUSPENDED SOLIDS ON THE DETECTION OF MUTAGENICITY WITH AMES TEST,BIOSIS COPYRIGHT: BIOL ABS. RRM MEETING ABSTRACT MEETING POSTER SALMONELLA-TYPHIMURIUM TA 100 TOXICOLOGY RIVER WATER SUSPENDED SOLIDS AMES TEST METHODOLOGY N-METHYL-N-NITRO-N-NITROSOGUANIDINE MUTAGEN ANALYSIS GENOTOXICITY POTASSIUM DICHROMATE ANALYTICAL METHOD RIO DE LA PLATA RIVER ARGENTINA,EFFECTS OF RIVER WATERS SUSPENDED SOLIDS ON THE DETECTION OF MUTAGENICITY WITH AMES TEST Abs: BIOSIS COPYRIGHT: BIOL ABS. RRM MEETING ABSTRACT MEETING POSTER SALMONELLA-TYPHIMURIUM TA 100 TOXICOLOGY RIVER WATER SUSPENDED SOLIDS AMES TEST METHODOLOGY N-METHYL-N-NITRO-N-NITROSOGUANIDINE MUTAGEN ANALYSIS GENOTOXICITY POTASSIUM DICHROMATE ANALYTICAL METHOD RIO DE LA PLATA RIVER ARGENTINA
1237540,Mayer et al. 1997,A simple in vitro fluorescence method for biomass measurements in algal growth inhibition tests,"BIOSIS COPYRIGHT: BIOL ABS. The estimation of biomass concentrations in algal growth inhibition tests from measurements of pigment fluorescence in extracts of 20% sample (final v/v) prepared by direct addition to dimethylsulfoxide/acetone solvent offers several advantages compared to currently used direct or indirect methods. The extraction stops the electron transfer and other processes which interact with chlorophyll fluorescence when measured in vivo. As a result the response is stabilized and the sensitivity improved. The injection method is very fast, has a high potential for automation, allows storage of samples and is suitable for small sample volumes (e.g. 0.2 ml). The typical initial cell density in standard toxicity tests of 104 cells ml-1 of Selenastrum capricornutum was measured precisely with a standard fluorimeter set-up, and 103 cells ml-1 of S. capricornutum was measured reliably with a sensitive fluorimeter. At low levels of toxicity by the model test compound potassium dichromate","A simple in vitro fluorescence method for biomass measurements in algal growth inhibition tests Abs: BIOSIS COPYRIGHT: BIOL ABS. The estimation of biomass concentrations in algal growth inhibition tests from measurements of pigment fluorescence in extracts of 20% sample (final v/v) prepared by direct addition to dimethylsulfoxide/acetone solvent offers several advantages compared to currently used direct or indirect methods. The extraction stops the electron transfer and other processes which interact with chlorophyll fluorescence when measured in vivo. As a result the response is stabilized and the sensitivity improved. The injection method is very fast, has a high potential for automation, allows storage of samples and is suitable for small sample volumes (e.g. 0.2 ml). The typical initial cell density in standard toxicity tests of 104 cells ml-1 of Selenastrum capricornutum was measured precisely with a standard fluorimeter set-up, and 103 cells ml-1 of S. capricornutum was measured reliably with a sensitive fluorimeter. At low levels of toxicity by the model test compound potassium dichromate"
1237539,Barnhart 1997,"Occurrences, uses, and properties of chromium","BIOSIS COPYRIGHT: BIOL ABS. Chromium is the 21st most abundant element in the Earth's crust with a mean concentration in United States soils of about 40 mg/kg. Although it exists in several oxidation states, the zero, trivalent, and hexavalent states are the most important in commercial products and the environment. Nearly all naturally occurring chromium is in the trivalent state, usually in combination with iron or other metal oxides. Although only about 15% of the chromium mined is used in the manufacture of chemicals, most applications of chromium utilize the chemistry of chromium. For instance, the ""stainless"" nature of stainless steel is due to the chemical properties of the chromium oxides which form on the surface of the alloy. Similarly, the protective properties of chrome plating of metals, chromated copper arsenate (CCA) treatment of wood, and chrome tanning of leather are all dependent on chromium chemistry. The key to these uses is that under typical environmental and biological condi","Occurrences, uses, and properties of chromium Abs: BIOSIS COPYRIGHT: BIOL ABS. Chromium is the 21st most abundant element in the Earth's crust with a mean concentration in United States soils of about 40 mg/kg. Although it exists in several oxidation states, the zero, trivalent, and hexavalent states are the most important in commercial products and the environment. Nearly all naturally occurring chromium is in the trivalent state, usually in combination with iron or other metal oxides. Although only about 15% of the chromium mined is used in the manufacture of chemicals, most applications of chromium utilize the chemistry of chromium. For instance, the ""stainless"" nature of stainless steel is due to the chemical properties of the chromium oxides which form on the surface of the alloy. Similarly, the protective properties of chrome plating of metals, chromated copper arsenate (CCA) treatment of wood, and chrome tanning of leather are all dependent on chromium chemistry. The key to these uses is that under typical environmental and biological condi"
1237536,De Coen and  Janssen 1997,"The use of biomarkers in Daphnia magna toxicity testing. II. Digestive enzyme activity in Daphnia magna exposed to sublethal concentrations of cadmium, chromium and mercury","BIOSIS COPYRIGHT: BIOL ABS. The effect of 48h and 96h exposure to sublethal concentrations of CdCl2, HgCl2 and K2Cr2O7 on the digestive enzyme activity of Daphnia magna was assessed. Five different digestive enzymes were investigated: cellulase, amylase, beta-galactosidase, trypsin and esterase. Both inhibition (CdCl2 and HgCl2) and increase (K2Cr2O7) of the enzyme activities were noted after short-term (48h) exposure. No inhibition, however, was observed after prolonged exposure (96h) to HgCl2 and K2Cr2O7 and even an increase in activity was noted for CdCl2. The increased digestive enzyme activity probably reflects the test organism's altered food assimilation efficiency in order to cope with the reduced food uptake. The observed changes in the digestive enzyme activity were furthermore evaluated as alternative effect criteria for chronic effect concentrations. Comparison of the enzymatic effect concentrations (1 and 2 enzyme LOEC's) with the LOEC's obtained for chronic reproduction tests (data","The use of biomarkers in Daphnia magna toxicity testing. II. Digestive enzyme activity in Daphnia magna exposed to sublethal concentrations of cadmium, chromium and mercury Abs: BIOSIS COPYRIGHT: BIOL ABS. The effect of 48h and 96h exposure to sublethal concentrations of CdCl2, HgCl2 and K2Cr2O7 on the digestive enzyme activity of Daphnia magna was assessed. Five different digestive enzymes were investigated: cellulase, amylase, beta-galactosidase, trypsin and esterase. Both inhibition (CdCl2 and HgCl2) and increase (K2Cr2O7) of the enzyme activities were noted after short-term (48h) exposure. No inhibition, however, was observed after prolonged exposure (96h) to HgCl2 and K2Cr2O7 and even an increase in activity was noted for CdCl2. The increased digestive enzyme activity probably reflects the test organism's altered food assimilation efficiency in order to cope with the reduced food uptake. The observed changes in the digestive enzyme activity were furthermore evaluated as alternative effect criteria for chronic effect concentrations. Comparison of the enzymatic effect concentrations (1 and 2 enzyme LOEC's) with the LOEC's obtained for chronic reproduction tests (data"
1237530,Sasaki et al. 1997,"Simple detection of chemical mutagens by the alkaline single-cell gel electrophoresis (Comet) assay in multiple mouse organs (liver, lung, spleen, kidney, and bone marrow)","BIOSIS COPYRIGHT: BIOL ABS. Recently, we designed a fast and simple method to obtain nuclei for the alkaline SCG assay and we tested it with mouse liver, lung, kidney, spleen, and bone marrow. Instead of isolating organ cells by trypsinization, we homogenized tissue and isolated the nuclei. Each organ was minced, and the mince was suspended in chilled homogenizing buffer containing NaCl and Na2EDTA, homogenized gently using a Potter-type homogenizer set in ice, and then centrifuged. The nuclei from the precipitate were used for the assay. To evaluate the validity of this method, we tested the genotoxicity in mouse organs of 11 chemical mutagens with different modes of action. Mice were sacrificed 3 and 24 h after administration of each mutagen. Treatment with three alkylating agents (MMS, EMS, and MNNG), a DNA crosslinking agent (MMC), two aromatic amines (2-AAF and phenacetin), a polycyclic aromatic hydrocarbon (B(a)P), and two inorganic chemicals (KBrO3 and K2CrO4) increased migration of the DNA","Simple detection of chemical mutagens by the alkaline single-cell gel electrophoresis (Comet) assay in multiple mouse organs (liver, lung, spleen, kidney, and bone marrow) Abs: BIOSIS COPYRIGHT: BIOL ABS. Recently, we designed a fast and simple method to obtain nuclei for the alkaline SCG assay and we tested it with mouse liver, lung, kidney, spleen, and bone marrow. Instead of isolating organ cells by trypsinization, we homogenized tissue and isolated the nuclei. Each organ was minced, and the mince was suspended in chilled homogenizing buffer containing NaCl and Na2EDTA, homogenized gently using a Potter-type homogenizer set in ice, and then centrifuged. The nuclei from the precipitate were used for the assay. To evaluate the validity of this method, we tested the genotoxicity in mouse organs of 11 chemical mutagens with different modes of action. Mice were sacrificed 3 and 24 h after administration of each mutagen. Treatment with three alkylating agents (MMS, EMS, and MNNG), a DNA crosslinking agent (MMC), two aromatic amines (2-AAF and phenacetin), a polycyclic aromatic hydrocarbon (B(a)P), and two inorganic chemicals (KBrO3 and K2CrO4) increased migration of the DNA"
1237529,Ferreiro et al. 1997,Is the white-ivory assay of Drosophila melanogaster a useful tool in genetic toxicology?,"BIOSIS COPYRIGHT: BIOL ABS. The white-ivory assay of Drosophila is based on the detection of reversions to wild-type phenotype of ommatidia with the white-ivory mutation. A tandem quadruplication of this gene is used in order to increase the reversion probability. Although the exact mechanism implicated in reversion is not known, revertant spots are believed to arise as a consequence of intrachromosomal recombination or related phenomena. Since the white-ivory assay has not been broadly used, the number of chemicals tested until now is still limited. In this work, we have assayed 25 chemicals belonging to several chemical groups, i.e., crosslinking agents, DNA-topoisomerase inhibitors, antimetabolites/nucleotide pool inhibitors, cyclic-adduct inducers, halogenated hydrocarbons, bulky-adduct inducers, intercalating agents, oxidative damage inducers, and a multiple damage inducer, to validate this test. Cross-linking agents, halogenated hydrocarbons, and the multiple damage inducer, daunomycin, were","Is the white-ivory assay of Drosophila melanogaster a useful tool in genetic toxicology? Abs: BIOSIS COPYRIGHT: BIOL ABS. The white-ivory assay of Drosophila is based on the detection of reversions to wild-type phenotype of ommatidia with the white-ivory mutation. A tandem quadruplication of this gene is used in order to increase the reversion probability. Although the exact mechanism implicated in reversion is not known, revertant spots are believed to arise as a consequence of intrachromosomal recombination or related phenomena. Since the white-ivory assay has not been broadly used, the number of chemicals tested until now is still limited. In this work, we have assayed 25 chemicals belonging to several chemical groups, i.e., crosslinking agents, DNA-topoisomerase inhibitors, antimetabolites/nucleotide pool inhibitors, cyclic-adduct inducers, halogenated hydrocarbons, bulky-adduct inducers, intercalating agents, oxidative damage inducers, and a multiple damage inducer, to validate this test. Cross-linking agents, halogenated hydrocarbons, and the multiple damage inducer, daunomycin, were"
1237528,Bollinger et al. 1997,Bioaccumulation of chromium in red swamp crayfish (Procambarus clarkii),"BIOSIS COPYRIGHT: BIOL ABS. Crayfish were exposed to a range of potassium dichromate concentrations (0.15, 0.30, 3.0 and 30 mg l-1) for periods up to 7 weeks. Chromium bioaccumulation in all tissues over the 7 week exposure period was not consistently time- and dose-dependent. The order of distribution of chromium into the various tissues was dependent upon the exposure concentration of the metal. Chromium clearance studies conducted 1 and 3 weeks following exposure demonstrated a concentration reduction in most tissues only at the highest exposure concentration of chromium (30 mg l-1). Histological studies demonstrated damage to both the gills and hepatopancreas at the lowest exposure concentration. The results suggest that the red swamp crayfish, Procambarus clarkii, is a useful biomarker for chromium exposure.","Bioaccumulation of chromium in red swamp crayfish (Procambarus clarkii) Abs: BIOSIS COPYRIGHT: BIOL ABS. Crayfish were exposed to a range of potassium dichromate concentrations (0.15, 0.30, 3.0 and 30 mg l-1) for periods up to 7 weeks. Chromium bioaccumulation in all tissues over the 7 week exposure period was not consistently time- and dose-dependent. The order of distribution of chromium into the various tissues was dependent upon the exposure concentration of the metal. Chromium clearance studies conducted 1 and 3 weeks following exposure demonstrated a concentration reduction in most tissues only at the highest exposure concentration of chromium (30 mg l-1). Histological studies demonstrated damage to both the gills and hepatopancreas at the lowest exposure concentration. The results suggest that the red swamp crayfish, Procambarus clarkii, is a useful biomarker for chromium exposure."
1237523,Mandervelt et al. 1997,Assessment of the sensitization potential of five metal salts in the murine local lymph node assay,"BIOSIS COPYRIGHT: BIOL ABS. The murine local lymph node assay (LLNA) has been proposed as a predictive test for the identification of sensitizing agents. We used this test to compare the sensitization potential of NiSO4, K2Cr2O7, CoCl2, Na2PtCl6 and BeSO4, salts of metals which have all been associated with allergic contact dermatitis and either bronchial asthma or interstitial lung disease, by either humoral or cell-mediated allergic mechanisms. BALB/c mice (n = 3 per concentration studied, three concentrations studied per metal) received three daily applications of the metal salt (in DMSO) on the dorsum of both ears. On the fourth day the draining auricular lymph nodes were removed and the incorporation of (3H)-thymidine in the lymphocytes in culture was compared to that of concurrent vehicle-treated control mice, thus enabling to derive a stimulation index (SI), indicative of immunological sensitization potential. Each experiment was performed three times. Oxazolone and toluene diisocyanate, c","Assessment of the sensitization potential of five metal salts in the murine local lymph node assay Abs: BIOSIS COPYRIGHT: BIOL ABS. The murine local lymph node assay (LLNA) has been proposed as a predictive test for the identification of sensitizing agents. We used this test to compare the sensitization potential of NiSO4, K2Cr2O7, CoCl2, Na2PtCl6 and BeSO4, salts of metals which have all been associated with allergic contact dermatitis and either bronchial asthma or interstitial lung disease, by either humoral or cell-mediated allergic mechanisms. BALB/c mice (n = 3 per concentration studied, three concentrations studied per metal) received three daily applications of the metal salt (in DMSO) on the dorsum of both ears. On the fourth day the draining auricular lymph nodes were removed and the incorporation of (3H)-thymidine in the lymphocytes in culture was compared to that of concurrent vehicle-treated control mice, thus enabling to derive a stimulation index (SI), indicative of immunological sensitization potential. Each experiment was performed three times. Oxazolone and toluene diisocyanate, c"
1237522,Carlisle et al. 1997,REGULATION OF CHROMIUM VI-INDUCED APOPTOSIS,BIOSIS COPYRIGHT: BIOL ABS. RRM MEETING ABSTRACT CHO CELL LINE HLF CELL LINE HUMAN LUNG FIBROBLASTS TUMOR BIOLOGY TOXICOLOGY LEAD CHROMATE CARCINOGENS INDUCED APOPTOSIS SODIUM CHROMATE P53 PROTEIN CERAMIDE SYNTHASE PATHWAY GENE EXPRESSION,REGULATION OF CHROMIUM VI-INDUCED APOPTOSIS Abs: BIOSIS COPYRIGHT: BIOL ABS. RRM MEETING ABSTRACT CHO CELL LINE HLF CELL LINE HUMAN LUNG FIBROBLASTS TUMOR BIOLOGY TOXICOLOGY LEAD CHROMATE CARCINOGENS INDUCED APOPTOSIS SODIUM CHROMATE P53 PROTEIN CERAMIDE SYNTHASE PATHWAY GENE EXPRESSION
1237521,Altamirano-Loranzo et al. 1997,Effect of some metal compounds on sperm motility in vitro,"In order to test in vitro the reprotoxic effects of various metal compounds, a system using pig spermatozoa was used. Semen samples were analysed and evaluated, transferred into a defined medium, treated with vanadium pentoxide (V2O5), lithium chloride (LiCl), potassium dichromate (K2Cr2O7), calcium chromate (CaCrO4), sodium arsenate (Na2HAsO4 . 7H(2)O), or mercuric chloride (HgCl2), and incubated for 4 to 5 h at 37 degrees C. 0, 1+, 2+, 3+, 4+, or 5+ h after treatment 20 mu L aliquots were examined to evaluate the sperm motility. HgCl2 was the most spermatoxic metal; after 15 min of exposure sperm motility was completely abolished at all doses. When the cells were treated with V2O5 or LiCl a dose-and time-dependent reduction in sperm motility was observed. K2Cr2O7 and Na2HAsO4 . 7H(2)O treatments had less evident effects on sperm motility, and CaCrO4 showed no significant effect. Our results show that metals may have different mechanisms of action on sperm motility, and that in vitro assays are excellent screening tests to establish the reproductive toxicity potential of the direct action of chemical agents.","Effect of some metal compounds on sperm motility in vitro Abs: In order to test in vitro the reprotoxic effects of various metal compounds, a system using pig spermatozoa was used. Semen samples were analysed and evaluated, transferred into a defined medium, treated with vanadium pentoxide (V2O5), lithium chloride (LiCl), potassium dichromate (K2Cr2O7), calcium chromate (CaCrO4), sodium arsenate (Na2HAsO4 . 7H(2)O), or mercuric chloride (HgCl2), and incubated for 4 to 5 h at 37 degrees C. 0, 1+, 2+, 3+, 4+, or 5+ h after treatment 20 mu L aliquots were examined to evaluate the sperm motility. HgCl2 was the most spermatoxic metal; after 15 min of exposure sperm motility was completely abolished at all doses. When the cells were treated with V2O5 or LiCl a dose-and time-dependent reduction in sperm motility was observed. K2Cr2O7 and Na2HAsO4 . 7H(2)O treatments had less evident effects on sperm motility, and CaCrO4 showed no significant effect. Our results show that metals may have different mechanisms of action on sperm motility, and that in vitro assays are excellent screening tests to establish the reproductive toxicity potential of the direct action of chemical agents."
1237519,Guin 1997,CONTACT DERMATITIS AND OTHER CONTACT REACTIONS,BIOSIS COPYRIGHT: BIOL ABS. RRM BOOK CHAPTER HUMAN PATIENT CONTACT DERMATITIS ALLERGIC CONTACT DERMATITIS DIFFERENTIAL DIAGNOSIS DERMATOLOGY PATCH TESTING EXFOLIATIVE DERMATITIS INTEGUMENTARY SYSTEM DISEASE IMMUNE SYSTEM DISEASE DIAGNOSTIC METHOD,CONTACT DERMATITIS AND OTHER CONTACT REACTIONS Abs: BIOSIS COPYRIGHT: BIOL ABS. RRM BOOK CHAPTER HUMAN PATIENT CONTACT DERMATITIS ALLERGIC CONTACT DERMATITIS DIFFERENTIAL DIAGNOSIS DERMATOLOGY PATCH TESTING EXFOLIATIVE DERMATITIS INTEGUMENTARY SYSTEM DISEASE IMMUNE SYSTEM DISEASE DIAGNOSTIC METHOD
1237516,Adachi et al. 1997,Potential efficacy of low metal diets and dental metal elimination in the management of atopic dermatitis: An open clinical study,"BIOSIS COPYRIGHT: BIOL ABS. We performed an open clinical study on the effects of low metal diets and/or dental metal elimination on 27 patients with moderate to severe atopic dermatitis (AD), who showed positive patch tests for metal allergens and/or clinical exacerbation by oral provocation tests with metal salts. All the patients were recommended to ingest low metal diets for 3 months and/or undergo dental metal elimination. Marked or moderate improvement was noted in 18 patients (67%); 7 patients (26%) showed marked improvement and 11 patients (41%), moderate improvement. Nine patients (33%) showed minimal improvement or no change. In the patients who showed marked or moderate improvement, we observed statistically significant decreases (p<0.05) in both peripheral blood eosinophil counts and serum LDH levels after 3 months of treatment. The present study suggests that restriction of ingested metal allergens to which patients have positive patch tests and/or oral challenge tests may be usefu","Potential efficacy of low metal diets and dental metal elimination in the management of atopic dermatitis: An open clinical study Abs: BIOSIS COPYRIGHT: BIOL ABS. We performed an open clinical study on the effects of low metal diets and/or dental metal elimination on 27 patients with moderate to severe atopic dermatitis (AD), who showed positive patch tests for metal allergens and/or clinical exacerbation by oral provocation tests with metal salts. All the patients were recommended to ingest low metal diets for 3 months and/or undergo dental metal elimination. Marked or moderate improvement was noted in 18 patients (67%); 7 patients (26%) showed marked improvement and 11 patients (41%), moderate improvement. Nine patients (33%) showed minimal improvement or no change. In the patients who showed marked or moderate improvement, we observed statistically significant decreases (p<0.05) in both peripheral blood eosinophil counts and serum LDH levels after 3 months of treatment. The present study suggests that restriction of ingested metal allergens to which patients have positive patch tests and/or oral challenge tests may be usefu"
1237515,Hattori et al. 1996,Epidemiological survey of metal allergy,"BIOSIS COPYRIGHT: BIOL ABS. Aichi-Gakuin university was one of the many academic institutions from all over Japan which participated in research activities into the ""Epidemiological survey of metal allergy and its relation to intraoral metal employment.'l Until 1991 and thereafter we continued similar research independently. We conducted patch tests of dental metal sensitization on 80 volunteers, with their informed consent. These 80 subjects consisted of 70 men and 10 women drawn from within this university, ranging in age from 18 to 42 and with an average age of 25.8 years. Patch tests were performed with 20 metallic elements, including 18 frequently used in dental restoration work and 2 more in different concentrations. The patch tests were carried out on the back of the subjects and readings were taken at three different times, i.e. after 2 days, 3 days and 7 days using the ICDRG standard. Results: Sensitization was found in 11 or 13.75% of the volunteer subjects. The rates of positive sensiti","Epidemiological survey of metal allergy Abs: BIOSIS COPYRIGHT: BIOL ABS. Aichi-Gakuin university was one of the many academic institutions from all over Japan which participated in research activities into the ""Epidemiological survey of metal allergy and its relation to intraoral metal employment.'l Until 1991 and thereafter we continued similar research independently. We conducted patch tests of dental metal sensitization on 80 volunteers, with their informed consent. These 80 subjects consisted of 70 men and 10 women drawn from within this university, ranging in age from 18 to 42 and with an average age of 25.8 years. Patch tests were performed with 20 metallic elements, including 18 frequently used in dental restoration work and 2 more in different concentrations. The patch tests were carried out on the back of the subjects and readings were taken at three different times, i.e. after 2 days, 3 days and 7 days using the ICDRG standard. Results: Sensitization was found in 11 or 13.75% of the volunteer subjects. The rates of positive sensiti"
1237513,Seidenari et al. 1997,Cross-sensitizations between azo dyes and para-amino compound: A study of 236 azo-dye-sensitive subjects,"BIOSIS COPYRIGHT: BIOL ABS. Combined sensitizations to different azo dyes, probably based both on true cross-sensitization and on simultaneous positive reactions, have frequently been described. However, since azo dyes are included in the standard series in a minority of countries, the case studies considered comprise, with few exceptions, a small number of subjects. The aim of our study was to investigate cross-reactions between different azo dyes and para-amino compounds in azo-dye-sensitive subjects, to study the clinical aspects of azo dye dermatitis, to assess the relevance of sensitization to azo dyes, and to relate the pattern of cross-sensitizations to the chemical structure of the different dyes. Out of 6203 consecutively tested patients, 236 were sensitized to at least 1 of 6 azo compounds employed as textile dyes, included in our standard series. 107 subjects reacted to Disperse Orange 3 (DO3), 104 to Disperse Blue 124 (DB124), 76 to p-aminoazobenzene (PAB), 67 to Disperse Red 1 (DR1)","Cross-sensitizations between azo dyes and para-amino compound: A study of 236 azo-dye-sensitive subjects Abs: BIOSIS COPYRIGHT: BIOL ABS. Combined sensitizations to different azo dyes, probably based both on true cross-sensitization and on simultaneous positive reactions, have frequently been described. However, since azo dyes are included in the standard series in a minority of countries, the case studies considered comprise, with few exceptions, a small number of subjects. The aim of our study was to investigate cross-reactions between different azo dyes and para-amino compounds in azo-dye-sensitive subjects, to study the clinical aspects of azo dye dermatitis, to assess the relevance of sensitization to azo dyes, and to relate the pattern of cross-sensitizations to the chemical structure of the different dyes. Out of 6203 consecutively tested patients, 236 were sensitized to at least 1 of 6 azo compounds employed as textile dyes, included in our standard series. 107 subjects reacted to Disperse Orange 3 (DO3), 104 to Disperse Blue 124 (DB124), 76 to p-aminoazobenzene (PAB), 67 to Disperse Red 1 (DR1)"
1237509,Botta et al. 1996,Genotoxic effects of potassium dichromate in cultural human lymphocytes,BIOSIS COPYRIGHT: BIOL ABS. Chromium derivatives are used in the steel industry. The trivalent form is the most common form but the hexavalent forms are of greater industrial importance. An impressive amounts of information is available regarding the genotoxicity of chromium derivatives. The hexavalent form can penetrate the cell whereas the trivalent form produced by metabolically reduction binds with nucleic acids. Chromium derivatives have not been tested in the cytokinesis-blocked micronucleus assay (CBMA). The present study compared the results obtained in a chromosome aberration test and in the CBMA. There was a dose-response relationship between chromosome aberrations and potassium dichromate in the range of 0.01-0.1 mug mL-1. Most abnormalities were chromatid gaps and breaks. The micronucleated binucleated cell rates rose significantly from the lower potassium dichromate concentration (0.01 mug mL-1) to the higher (0.25 mug mL-1). These results indicate that potassium dichromate seems to,Genotoxic effects of potassium dichromate in cultural human lymphocytes Abs: BIOSIS COPYRIGHT: BIOL ABS. Chromium derivatives are used in the steel industry. The trivalent form is the most common form but the hexavalent forms are of greater industrial importance. An impressive amounts of information is available regarding the genotoxicity of chromium derivatives. The hexavalent form can penetrate the cell whereas the trivalent form produced by metabolically reduction binds with nucleic acids. Chromium derivatives have not been tested in the cytokinesis-blocked micronucleus assay (CBMA). The present study compared the results obtained in a chromosome aberration test and in the CBMA. There was a dose-response relationship between chromosome aberrations and potassium dichromate in the range of 0.01-0.1 mug mL-1. Most abnormalities were chromatid gaps and breaks. The micronucleated binucleated cell rates rose significantly from the lower potassium dichromate concentration (0.01 mug mL-1) to the higher (0.25 mug mL-1). These results indicate that potassium dichromate seems to
1237508,Lahr 1997,Ecotoxicology of organisms adapted to life in temporary freshwater ponds in arid and semi-arid regions,"BIOSIS COPYRIGHT: BIOL ABS. Hot arid and semi-arid zones are characterized by an abundance of temporary ponds. Most of these depend on rain for their existence. These habitats are distinguished by fluctuating and unpredictable changes in their hydrological regime and of physical and chemical conditions. They contain a uniquely-adapted fauna that copes in different ways with changing and often extreme temperatures, oxygen levels, pH, salinity and turbidity. A classification is presented of the most distinctive adaptations, the various tactics that organisms apply to survive dry periods. The main strategies are dormancy (escape in time) and dispersal (escape in space). These adaptations may affect the impact of toxicants on individuals, populations and communities of temporary ponds. The physiological adaptations of species found in temporary ponds are likely to alter the sensitivity to pollutants of characteristic species. Results from laboratory experiments, for example, suggest that fairy shrimp","Ecotoxicology of organisms adapted to life in temporary freshwater ponds in arid and semi-arid regions Abs: BIOSIS COPYRIGHT: BIOL ABS. Hot arid and semi-arid zones are characterized by an abundance of temporary ponds. Most of these depend on rain for their existence. These habitats are distinguished by fluctuating and unpredictable changes in their hydrological regime and of physical and chemical conditions. They contain a uniquely-adapted fauna that copes in different ways with changing and often extreme temperatures, oxygen levels, pH, salinity and turbidity. A classification is presented of the most distinctive adaptations, the various tactics that organisms apply to survive dry periods. The main strategies are dormancy (escape in time) and dispersal (escape in space). These adaptations may affect the impact of toxicants on individuals, populations and communities of temporary ponds. The physiological adaptations of species found in temporary ponds are likely to alter the sensitivity to pollutants of characteristic species. Results from laboratory experiments, for example, suggest that fairy shrimp"
1237507,Everts 1997,Ecotoxicology for risk assessment in arid zones: Some key issues,"BIOSIS COPYRIGHT: BIOL ABS. In the hot arid zones of the world, ecotoxicological research is in statu nascendi. In these zones, the major sources of contamination by toxicants are: (1) plant protection and vector control in wet zones; (2) large-scale crop protection campaigns in dry and ephemeral wet zones; (3) refuse and obsolete pesticides in dry zones; and (4) mining. Economic development in many of these zones requires an adequate knowledge of certain basic principles, i.e., where extrapolating existing knowledge does not apply. The vulnerability of ecosystems to contaminants is closely related to water flow. In dry areas, species are susceptible to factors that interfere with the ecophysiological properties regulating water loss. Most hot arid areas are found at low latitudes where temperatures show striking extremes both in time and space. Living organisms are physiologically resistant and/or show adaptive behavior to these temperature extremes. Very little is known about the effects of toxi","Ecotoxicology for risk assessment in arid zones: Some key issues Abs: BIOSIS COPYRIGHT: BIOL ABS. In the hot arid zones of the world, ecotoxicological research is in statu nascendi. In these zones, the major sources of contamination by toxicants are: (1) plant protection and vector control in wet zones; (2) large-scale crop protection campaigns in dry and ephemeral wet zones; (3) refuse and obsolete pesticides in dry zones; and (4) mining. Economic development in many of these zones requires an adequate knowledge of certain basic principles, i.e., where extrapolating existing knowledge does not apply. The vulnerability of ecosystems to contaminants is closely related to water flow. In dry areas, species are susceptible to factors that interfere with the ecophysiological properties regulating water loss. Most hot arid areas are found at low latitudes where temperatures show striking extremes both in time and space. Living organisms are physiologically resistant and/or show adaptive behavior to these temperature extremes. Very little is known about the effects of toxi"
1237503,Magdaleno et al. 1997,"Preliminary toxicity tests using the green alga, Ankistrodesmus falcatus","BIOSIS COPYRIGHT: BIOL ABS. The freshwater green alga Ankistrodesmus falcatus was cultured in increasing concentrations of Cr, Hg, Cd, Zn, and Al to evaluate the effect of these cations on its growth. Algal growth was estimated by absorbance at 750 nm. Potassium dichromate was used as reference for test reproducibility. The EC50 for 3 tests was 1.890 mg L-1 with a coefficient of variation of 40.25%. The 96 h static EC50's for heavy metals (in mg L-1 of nominal concentrations) were as follows: Cr6+2Cr2O7, 1.050; Hg2+/Hg(SCN)2, 0.162; Hg2+/HgCl2, 0.074; Cd2+/CdCl2. H2O, 0.292; Zn2+/ZnSO4. 7H2O, 2.432; and Al3+/Al2(SO4)3 Cd Al Cr Zn. These preliminary results suggest that bioassays using A. falcatus could be suitable for evaluating the toxicity of heavy metals in freshwaters.","Preliminary toxicity tests using the green alga, Ankistrodesmus falcatus Abs: BIOSIS COPYRIGHT: BIOL ABS. The freshwater green alga Ankistrodesmus falcatus was cultured in increasing concentrations of Cr, Hg, Cd, Zn, and Al to evaluate the effect of these cations on its growth. Algal growth was estimated by absorbance at 750 nm. Potassium dichromate was used as reference for test reproducibility. The EC50 for 3 tests was 1.890 mg L-1 with a coefficient of variation of 40.25%. The 96 h static EC50's for heavy metals (in mg L-1 of nominal concentrations) were as follows: Cr6+2Cr2O7, 1.050; Hg2+/Hg(SCN)2, 0.162; Hg2+/HgCl2, 0.074; Cd2+/CdCl2. H2O, 0.292; Zn2+/ZnSO4. 7H2O, 2.432; and Al3+/Al2(SO4)3 Cd Al Cr Zn. These preliminary results suggest that bioassays using A. falcatus could be suitable for evaluating the toxicity of heavy metals in freshwaters."
1237501,Jetly and  Srivastava 1995,Monitoring of chromium phytotoxicity in some crops: Effect on seed germination and seedling growth,"BIOSIS COPYRIGHT: BIOL ABS. Phytotoxicity of hexavalent chromium, given in the form of potassium chromate was evaluated, using seed germination and seedling growth as criteria, in four crops, Helianthus annuus cv modern Vigna mungo cv PU 19, Triticum aestivum cv UP 262 and Zea mays cv naveen. Treatments were given with seven molar concentrations, 10-7 M, 10-6 M, 10-5 M, 10-4 M, 10-3 M, 10-2 M and 10-1 M, to seeds/seedlings in darkness. Cr+6 reduced seed germination and retarded seedling growth in all the four crops. The amount of phytotoxicity incurred depended on concentration of potassium chromate, duration of treatment and genotype of the cultivars.","Monitoring of chromium phytotoxicity in some crops: Effect on seed germination and seedling growth Abs: BIOSIS COPYRIGHT: BIOL ABS. Phytotoxicity of hexavalent chromium, given in the form of potassium chromate was evaluated, using seed germination and seedling growth as criteria, in four crops, Helianthus annuus cv modern Vigna mungo cv PU 19, Triticum aestivum cv UP 262 and Zea mays cv naveen. Treatments were given with seven molar concentrations, 10-7 M, 10-6 M, 10-5 M, 10-4 M, 10-3 M, 10-2 M and 10-1 M, to seeds/seedlings in darkness. Cr+6 reduced seed germination and retarded seedling growth in all the four crops. The amount of phytotoxicity incurred depended on concentration of potassium chromate, duration of treatment and genotype of the cultivars."
1237500,Katsarou et al. 1996,PATCH TESTS IN CHILDREN A REVIEW OF 14 YEARS EXPERIENCE,BIOSIS COPYRIGHT: BIOL ABS. RRM NOTE HAIRDRESSER CONSTRUCTION WORKER METALS FRAGRANCES PRESERVATIVES ALLERGIC CONTACT DERMATITIS OCCUPATIONAL TOXICITY HAZARDOUS MATERIALS,PATCH TESTS IN CHILDREN A REVIEW OF 14 YEARS EXPERIENCE Abs: BIOSIS COPYRIGHT: BIOL ABS. RRM NOTE HAIRDRESSER CONSTRUCTION WORKER METALS FRAGRANCES PRESERVATIVES ALLERGIC CONTACT DERMATITIS OCCUPATIONAL TOXICITY HAZARDOUS MATERIALS
1237497,Santucci et al. 1996,Multiple sensitivities to transition metals: The nickel palladium reactions,"BIOSIS COPYRIGHT: BIOL ABS. Patch test data of 1000 consecutive patients sensitive to at least 1 substance of our standard series showed that transition metals gave associated reactions amongst themselves more frequently than they did with the remaining substances. The responses to transition metals were largely variable and seemed dependent not only upon the associated exposure to different metals or the concomitant responses of the T cell clones, as reported by others, but also upon the chemical properties of the metals and the consequent interactions inside the skin. Concomitant reactions to nickel sulfate and palladium chloride were the most frequently found associated positivities and occurred in a minority of nickel-sulfate-sensitive subjects. In 43 out of 45 of these subjects, patch tests to mixed solutions containing nickel sulfate, plus sulfates of magnesium, zinc, and manganese at higher doses, were not able to reduce the nickel sulfate reactions. This behaviour contrasted with that foun","Multiple sensitivities to transition metals: The nickel palladium reactions Abs: BIOSIS COPYRIGHT: BIOL ABS. Patch test data of 1000 consecutive patients sensitive to at least 1 substance of our standard series showed that transition metals gave associated reactions amongst themselves more frequently than they did with the remaining substances. The responses to transition metals were largely variable and seemed dependent not only upon the associated exposure to different metals or the concomitant responses of the T cell clones, as reported by others, but also upon the chemical properties of the metals and the consequent interactions inside the skin. Concomitant reactions to nickel sulfate and palladium chloride were the most frequently found associated positivities and occurred in a minority of nickel-sulfate-sensitive subjects. In 43 out of 45 of these subjects, patch tests to mixed solutions containing nickel sulfate, plus sulfates of magnesium, zinc, and manganese at higher doses, were not able to reduce the nickel sulfate reactions. This behaviour contrasted with that foun"
1237492,Milkovic-Kraus and  Macan 1996,Can pre-employment patch testing help to prevent occupational contact allergy?,"BIOSIS COPYRIGHT: BIOL ABS. 175 subjects (157 female, 18 male) were patch tested with a standard series of allergens (Epipharm Allergy Service, GmbH, Linz, Austria), during pre-employment examinations in the pharmaceutical industry, considered an industry at risk for the development of contact sensitization. None of those examined had contact dermatitis prior to testing and none gave a positive history of hand eczema. Patch testing was positive in 12 (7%) subjects, of whom 7 showed a positive reaction to only 1 contact allergen and 5 reacted to several contact allergens. 5 subjects (2.9%) reacted positively to metal salts (nickel, cobalt, chromium), 5 (2.9%) had a positive skin reaction to mixtures of rubber additives, and the remaining 2 to other allergens.","Can pre-employment patch testing help to prevent occupational contact allergy? Abs: BIOSIS COPYRIGHT: BIOL ABS. 175 subjects (157 female, 18 male) were patch tested with a standard series of allergens (Epipharm Allergy Service, GmbH, Linz, Austria), during pre-employment examinations in the pharmaceutical industry, considered an industry at risk for the development of contact sensitization. None of those examined had contact dermatitis prior to testing and none gave a positive history of hand eczema. Patch testing was positive in 12 (7%) subjects, of whom 7 showed a positive reaction to only 1 contact allergen and 5 reacted to several contact allergens. 5 subjects (2.9%) reacted positively to metal salts (nickel, cobalt, chromium), 5 (2.9%) had a positive skin reaction to mixtures of rubber additives, and the remaining 2 to other allergens."
1237484,Mclelland and  Shuster 1996,Patch testing with a combination of unrelated allergens: A new strategy,"BIOSIS COPYRIGHT: BIOL ABS. A simplified method of patch testing was designed, in which several totally unrelated allergens were combined in each patch. The method was evaluated by double blind comparison of responses to 17 standard allergens applied individually as 17 conventional patch tests, and as two different sets of five patches each containing combinations of three or four allergens per patch, in 137 patients under investigation for contact allergic dermatitis. There were 8 9 positive responses to conventional patch testing with separate allergens and 94 and 86 positives to the two different combinations of the same allergens. Concordance of positive reactions to the two combinations was 80% and there were no irritant reactions. Conventional testing detected 70 and 74% of reactions to combination patches 1 and 2 and combination patches 1 and 2 detected 80 and 79% of the reactions to conventional testing. The combinations detected clinically relevant sensitivities not found by conventional","Patch testing with a combination of unrelated allergens: A new strategy Abs: BIOSIS COPYRIGHT: BIOL ABS. A simplified method of patch testing was designed, in which several totally unrelated allergens were combined in each patch. The method was evaluated by double blind comparison of responses to 17 standard allergens applied individually as 17 conventional patch tests, and as two different sets of five patches each containing combinations of three or four allergens per patch, in 137 patients under investigation for contact allergic dermatitis. There were 8 9 positive responses to conventional patch testing with separate allergens and 94 and 86 positives to the two different combinations of the same allergens. Concordance of positive reactions to the two combinations was 80% and there were no irritant reactions. Conventional testing detected 70 and 74% of reactions to combination patches 1 and 2 and combination patches 1 and 2 detected 80 and 79% of the reactions to conventional testing. The combinations detected clinically relevant sensitivities not found by conventional"
1237483,Genter 1996,ECOTOXICOLOGY OF INORGANIC CHEMICAL STRESS TO ALGAE,BIOSIS COPYRIGHT: BIOL ABS. RRM BOOK CHAPTER ALGAE SEAWEEDS FRESHWATER ECOLOGY ECOTOXICOLOGY INORGANIC CHEMICAL STRESS INDUCER TOXICITY TOXIN UPTAKE METAL PERIPHYTON COMMUNITY PHYTOPLANKTON COMMUNITY SCHEMATIC MODEL SEDIMENT WATER CONDITIONS ACCLIMATION COTOLERANCE STRESS RESPONSE TOXICOLOGY,ECOTOXICOLOGY OF INORGANIC CHEMICAL STRESS TO ALGAE Abs: BIOSIS COPYRIGHT: BIOL ABS. RRM BOOK CHAPTER ALGAE SEAWEEDS FRESHWATER ECOLOGY ECOTOXICOLOGY INORGANIC CHEMICAL STRESS INDUCER TOXICITY TOXIN UPTAKE METAL PERIPHYTON COMMUNITY PHYTOPLANKTON COMMUNITY SCHEMATIC MODEL SEDIMENT WATER CONDITIONS ACCLIMATION COTOLERANCE STRESS RESPONSE TOXICOLOGY
1237482,Fung and  Maibach 1996,SO-CALLED MARGINAL PATCH TEST IRRITATION ATTEMPT AT A PREDICTIVE ASSAY,BIOSIS COPYRIGHT: BIOL ABS. RRM NOTE RESEARCH ARTICLE HUMAN ALLERGY DERMATOLOGY TOXICOLOGY CONTACT DERMATITIS MARGINAL PATCH TEST IRRITATION POTASSIUM DICHROMATE PARABENS CARBA MIX THIURAM MIX NEOMYCIN SULFATE METHODS TECHNIQUES AND EQUIPMENT TOXICITY INTEGUMENTARY SYSTEM DISEASE IMMUNE SYSTEM DISEASE DIAGNOSTIC METHOD PREDICTIVE ASSAY CLINICAL APPLICATION,SO-CALLED MARGINAL PATCH TEST IRRITATION ATTEMPT AT A PREDICTIVE ASSAY Abs: BIOSIS COPYRIGHT: BIOL ABS. RRM NOTE RESEARCH ARTICLE HUMAN ALLERGY DERMATOLOGY TOXICOLOGY CONTACT DERMATITIS MARGINAL PATCH TEST IRRITATION POTASSIUM DICHROMATE PARABENS CARBA MIX THIURAM MIX NEOMYCIN SULFATE METHODS TECHNIQUES AND EQUIPMENT TOXICITY INTEGUMENTARY SYSTEM DISEASE IMMUNE SYSTEM DISEASE DIAGNOSTIC METHOD PREDICTIVE ASSAY CLINICAL APPLICATION
1237480,Lee and  Lam 1996,Patch testing of 490 patients in Hong Kong,"BIOSIS COPYRIGHT: BIOL ABS. Patch testing, using European standard allergens and suspected causative substances brought in by patients, was carried out in 490 patients with eczema in Hong Kong and 437 completed the test. Before patch testing, 244, 141 and 105 patients were diagnosed as having contact dermatitis, endogenous eczema and unclassified eczema, respectively. After patch testing, the diagnosis of the causal agent was changed in 54 contact dermatitis patients, and 18% of endogenous eczema patients and 34% of unclassified eczema patients were re-diagnosed as contact dermatitis. In the patients with a final diagnosis of contact dermatitis, 19.5% were positive to fragrance mix, followed by nickel sulfate (16.4%) and cobalt chloride (11.3%). The commonest causative agents for contact dermatitis were soap or detergent (22.0%) and traditional Chinese medicine (17.3%); the latter was a more common cause of contact dermatitis than Western medicine (9.0%) or metals (13.4%). The prevalence of allerg","Patch testing of 490 patients in Hong Kong Abs: BIOSIS COPYRIGHT: BIOL ABS. Patch testing, using European standard allergens and suspected causative substances brought in by patients, was carried out in 490 patients with eczema in Hong Kong and 437 completed the test. Before patch testing, 244, 141 and 105 patients were diagnosed as having contact dermatitis, endogenous eczema and unclassified eczema, respectively. After patch testing, the diagnosis of the causal agent was changed in 54 contact dermatitis patients, and 18% of endogenous eczema patients and 34% of unclassified eczema patients were re-diagnosed as contact dermatitis. In the patients with a final diagnosis of contact dermatitis, 19.5% were positive to fragrance mix, followed by nickel sulfate (16.4%) and cobalt chloride (11.3%). The commonest causative agents for contact dermatitis were soap or detergent (22.0%) and traditional Chinese medicine (17.3%); the latter was a more common cause of contact dermatitis than Western medicine (9.0%) or metals (13.4%). The prevalence of allerg"
1237479,Brasch et al. 1996,Dynamic patterns of allergic patch test reactions to 10 European standard allergens,"BIOSIS COPYRIGHT: BIOL ABS. Insight into the dynamic time courses of patch test reactions may be useful for patch test evaluation. To put this to the proof, we have analysed the time courses of allergic patch test reactions that were filed between 1990 and 1994 by the Information Network of Departments of Dermatology in Germany (IVDK). Based on reaction strength at days 1 to 3, each allergic patch test was assigned to 1 of 5 distinct dynamic reaction patterns: crescendo, plateau, decrescendo, crescendo/decrescendo, or decrescendo/crescendo. The frequencies of these patterns were determined for those 10 standard allergens yielding the highest numbers of allergic reactions (n between 180 and 1240), and dynamic patterns were classified as type 1 (crescendo or plateau patterns) or type 2 (other patterns). Influences of population characteristics upon the classification of patterns were evaluated by logistic regression analyses. Different frequencies of reaction patterns were found for distinct allergen","Dynamic patterns of allergic patch test reactions to 10 European standard allergens Abs: BIOSIS COPYRIGHT: BIOL ABS. Insight into the dynamic time courses of patch test reactions may be useful for patch test evaluation. To put this to the proof, we have analysed the time courses of allergic patch test reactions that were filed between 1990 and 1994 by the Information Network of Departments of Dermatology in Germany (IVDK). Based on reaction strength at days 1 to 3, each allergic patch test was assigned to 1 of 5 distinct dynamic reaction patterns: crescendo, plateau, decrescendo, crescendo/decrescendo, or decrescendo/crescendo. The frequencies of these patterns were determined for those 10 standard allergens yielding the highest numbers of allergic reactions (n between 180 and 1240), and dynamic patterns were classified as type 1 (crescendo or plateau patterns) or type 2 (other patterns). Influences of population characteristics upon the classification of patterns were evaluated by logistic regression analyses. Different frequencies of reaction patterns were found for distinct allergen"
1237475,Spano et al. 1996,RECOMBINAGENIC ACTIVITY OF FOUR COMPOUNDS IN THE STANDARD AND HIGH BIOACTIVATION CROSSES OF THE WING SPOT TEST IN DROSOPHILA MELANOGASTER,BIOSIS COPYRIGHT: BIOL ABS. RRM MEETING ABSTRACT DROSOPHILA-MELANOGASTER POTASSIUM CHROMATE CYCLOPHOSPHAMIDE P-DIMETHYLAMINOAZOBENZENE 9 10-DIMETHYLANTHRACENE GENOTOXICITY MUTATION ANALYSIS MITOTIC RECOMBINATION,RECOMBINAGENIC ACTIVITY OF FOUR COMPOUNDS IN THE STANDARD AND HIGH BIOACTIVATION CROSSES OF THE WING SPOT TEST IN DROSOPHILA MELANOGASTER Abs: BIOSIS COPYRIGHT: BIOL ABS. RRM MEETING ABSTRACT DROSOPHILA-MELANOGASTER POTASSIUM CHROMATE CYCLOPHOSPHAMIDE P-DIMETHYLAMINOAZOBENZENE 9 10-DIMETHYLANTHRACENE GENOTOXICITY MUTATION ANALYSIS MITOTIC RECOMBINATION
1237470,Whitehouse et al. 1996,Aquatic toxicity tests for the control of effluent discharges in the UK - the influence of test precision,"BIOSIS COPYRIGHT: BIOL ABS. The initiative by the River Purification Boards (RPBs), National Rivers Authority (NRA) and Her Majesty's Inspectorate of Pollution (HMIP) to control certain complex and toxic effluent discharges by direct toxicity assessment places great emphasis on the use of aquatic toxicity tests. Like all biological and analytical measurements, determinations of toxicity exhibit variability. When setting 'Toxicity-based Consents' (TBCs) and monitoring for compliance with such consents, it is important to understand and if possible control this variability. The implications of toxicity test variability for the way TBCs may be set and monitored are discussed; including a consideration of monitoring consents based on a single exposure concentration (limit) test and procedures involving a range of exposure concentrations (concentration-response test). We also review the precision of data arising from acute aquatic toxicity test methods which may be used for the control and monitoring o","Aquatic toxicity tests for the control of effluent discharges in the UK - the influence of test precision Abs: BIOSIS COPYRIGHT: BIOL ABS. The initiative by the River Purification Boards (RPBs), National Rivers Authority (NRA) and Her Majesty's Inspectorate of Pollution (HMIP) to control certain complex and toxic effluent discharges by direct toxicity assessment places great emphasis on the use of aquatic toxicity tests. Like all biological and analytical measurements, determinations of toxicity exhibit variability. When setting 'Toxicity-based Consents' (TBCs) and monitoring for compliance with such consents, it is important to understand and if possible control this variability. The implications of toxicity test variability for the way TBCs may be set and monitored are discussed; including a consideration of monitoring consents based on a single exposure concentration (limit) test and procedures involving a range of exposure concentrations (concentration-response test). We also review the precision of data arising from acute aquatic toxicity test methods which may be used for the control and monitoring o"
1237469,Barbieri et al. 1996,Mercury resistance in aromatic compound degrading Pseudomonas strains,BIOSIS COPYRIGHT: BIOL ABS. Six of ten Pseudomonas strains selected from environmental samples for their ability to degrade aromatic compounds were found to be mercury resistant. Mercury detoxification proceeded through Hg2+ volatilization and the genes involved were chromosomally located. All the mercury resistant strains proved able to degrade aromatic compounds in the presence of Hg2+.,Mercury resistance in aromatic compound degrading Pseudomonas strains Abs: BIOSIS COPYRIGHT: BIOL ABS. Six of ten Pseudomonas strains selected from environmental samples for their ability to degrade aromatic compounds were found to be mercury resistant. Mercury detoxification proceeded through Hg2+ volatilization and the genes involved were chromosomally located. All the mercury resistant strains proved able to degrade aromatic compounds in the presence of Hg2+.
1237465,Jovanovic and  Poljacki 1996,RELATIVE INCIDENCE OF ALLERGIC REACTIONS TO CONTACT ALLERGENS,BIOSIS COPYRIGHT: BIOL ABS. RRM MEETING ABSTRACT HUMAN PATIENT MEDICAL SCIENCES-HUMAN MEDICINE-CLINICAL IMMUNOLOGY-ALLERGY ALLERGIC REACTIONS MEDICAL SCIENCES-HUMAN MEDICINE-DERMATOLOGY CONTACT ALLERGENS RELATIVE INCIDENCE STATISTICAL ANALYSIS ALLERGIC CONTACT DERMATITIS PATCH TEST NICKEL SULFATE PERU BALSAM POTASSIUM DICHROMATE FRAGRANCE MIX FORMALDEHYDE COBALT CHLORIDE PARAPHENYLENEDIAMINE IMMUNE SYSTEM DISEASE INTEGUMENTARY SYSTEM DISEASE DIAGNOSTIC METHOD,RELATIVE INCIDENCE OF ALLERGIC REACTIONS TO CONTACT ALLERGENS Abs: BIOSIS COPYRIGHT: BIOL ABS. RRM MEETING ABSTRACT HUMAN PATIENT MEDICAL SCIENCES-HUMAN MEDICINE-CLINICAL IMMUNOLOGY-ALLERGY ALLERGIC REACTIONS MEDICAL SCIENCES-HUMAN MEDICINE-DERMATOLOGY CONTACT ALLERGENS RELATIVE INCIDENCE STATISTICAL ANALYSIS ALLERGIC CONTACT DERMATITIS PATCH TEST NICKEL SULFATE PERU BALSAM POTASSIUM DICHROMATE FRAGRANCE MIX FORMALDEHYDE COBALT CHLORIDE PARAPHENYLENEDIAMINE IMMUNE SYSTEM DISEASE INTEGUMENTARY SYSTEM DISEASE DIAGNOSTIC METHOD
1237464,James 1996,THE CHALLENGE OF REMEDIATING CHROMIUM-CONTAMINATED SOIL,BIOSIS COPYRIGHT: BIOL ABS. RRM JOURNAL ARTICLE HUMAN HEXAVALENT CHROMIUM SALT CHROMIUM BLOOM HEAVY METAL REDUCTION REACTION SOIL POLLUTION CONTAMINATION HEALTH HAZARD CLEANUP NEW JERSEY USA,THE CHALLENGE OF REMEDIATING CHROMIUM-CONTAMINATED SOIL Abs: BIOSIS COPYRIGHT: BIOL ABS. RRM JOURNAL ARTICLE HUMAN HEXAVALENT CHROMIUM SALT CHROMIUM BLOOM HEAVY METAL REDUCTION REACTION SOIL POLLUTION CONTAMINATION HEALTH HAZARD CLEANUP NEW JERSEY USA
1237463,Bruze et al. 1996,Occupational dermatoses in a Swedish aircraft plant,"BIOSIS COPYRIGHT: BIOL ABS. A survey of occupational dermatoses, based on a questionnaire, clinical examination and patch testing, was carried out among 341 workers in an aircraft plant. The questionnaire was answered by 330 workers (96.8%). Present or previous skin disease was reported by 92 employees, who were all subjected to physical examination and patch testing. Patch testing was conducted with a standard series, as well as with a series of substances and products representing the work environment. Occupational contact allergies were established in 12 employees. In total, the figure for occupational skin diseases was 16.1% (55 workers), when calculated for all employees.","Occupational dermatoses in a Swedish aircraft plant Abs: BIOSIS COPYRIGHT: BIOL ABS. A survey of occupational dermatoses, based on a questionnaire, clinical examination and patch testing, was carried out among 341 workers in an aircraft plant. The questionnaire was answered by 330 workers (96.8%). Present or previous skin disease was reported by 92 employees, who were all subjected to physical examination and patch testing. Patch testing was conducted with a standard series, as well as with a series of substances and products representing the work environment. Occupational contact allergies were established in 12 employees. In total, the figure for occupational skin diseases was 16.1% (55 workers), when calculated for all employees."
1237462,Stables et al. 1996,Patch testing in children,"BIOSIS COPYRIGHT: BIOL ABS. 92 children (45 girls, 47 boys), mean age 9.3 years (3-14.75), were referred to the Contact Dermatitis Investigation Unit, Belvidere Hospital, Glasgow, for patch testing during the period 1979-93 for the investigation of allergic contact dermatitis (ACD). The diagnoses at the time of referral were atopic dermatitis (45), non-atopic with localized dermatitis (26), juvenile plantar dermatosis (15), orofacial granulomatosis (2), vaccination reaction (2) and atypical psoriasis (2). In total, there were 55 positive reactions in 30 children. The commonest allergens were metals (18), fragrances (11) and rubber compounds (6). The patient groups with the highest yield of positive patch tests were those patients with atopic dermatitis who had a good history of a precipitating contact factor (4/5), and non-atopic patients with dermatitis of hands and/or feet (7/14). Our findings suggest that allergic contact dermatitis is more common in children than generally appreciated and that","Patch testing in children Abs: BIOSIS COPYRIGHT: BIOL ABS. 92 children (45 girls, 47 boys), mean age 9.3 years (3-14.75), were referred to the Contact Dermatitis Investigation Unit, Belvidere Hospital, Glasgow, for patch testing during the period 1979-93 for the investigation of allergic contact dermatitis (ACD). The diagnoses at the time of referral were atopic dermatitis (45), non-atopic with localized dermatitis (26), juvenile plantar dermatosis (15), orofacial granulomatosis (2), vaccination reaction (2) and atypical psoriasis (2). In total, there were 55 positive reactions in 30 children. The commonest allergens were metals (18), fragrances (11) and rubber compounds (6). The patient groups with the highest yield of positive patch tests were those patients with atopic dermatitis who had a good history of a precipitating contact factor (4/5), and non-atopic patients with dermatitis of hands and/or feet (7/14). Our findings suggest that allergic contact dermatitis is more common in children than generally appreciated and that"
1237459,Guo et al. 1996,Prevalence of dermatoses and skin sensitisation associated with use of pesticides in fruit farmers of southern Taiwan,"BIOSIS COPYRIGHT: BIOL ABS. Objectives Agricultural workers are known to have occupational skin diseases. The prevalence and pattern of skin diseases are unknown in Taiwanese fruit farmers. The objective of this study is to determine the work exposure, prevalence of skin diseases, and sensitivity to common skin allergens and agricultural chemicals in fruit farmers of southern Taiwan. Methods 122 fruit farmers who regularly prepared and sprayed pesticides and a group of 63 printing press workers with no known exposure to pesticides were examined and patch tested with common skin allergens and agricultural chemicals. The farmers were also interviewed for their work habits, use of protective clothing, and exposure to pesticides. Results Most farmers reported regular use of hat, boots, and mask, but not gloves, raincoat, and goggles. This resulted in frequent skin contact with pesticides especially on the hands and face. About 30% of farmers had hand dermatitis, and more than two thirds had pigmentati","Prevalence of dermatoses and skin sensitisation associated with use of pesticides in fruit farmers of southern Taiwan Abs: BIOSIS COPYRIGHT: BIOL ABS. Objectives Agricultural workers are known to have occupational skin diseases. The prevalence and pattern of skin diseases are unknown in Taiwanese fruit farmers. The objective of this study is to determine the work exposure, prevalence of skin diseases, and sensitivity to common skin allergens and agricultural chemicals in fruit farmers of southern Taiwan. Methods 122 fruit farmers who regularly prepared and sprayed pesticides and a group of 63 printing press workers with no known exposure to pesticides were examined and patch tested with common skin allergens and agricultural chemicals. The farmers were also interviewed for their work habits, use of protective clothing, and exposure to pesticides. Results Most farmers reported regular use of hat, boots, and mask, but not gloves, raincoat, and goggles. This resulted in frequent skin contact with pesticides especially on the hands and face. About 30% of farmers had hand dermatitis, and more than two thirds had pigmentati"
1237458,Nasir and  Gaspari 1996,CONTACT DERMATITIS CLINICAL PERSPECTIVES AND BASIC MECHANISMS,BIOSIS COPYRIGHT: BIOL ABS. RRM LITERATURE REVIEW HUMAN ALLERGY ECZEMA TOXICITY THERAPY PLANNING,CONTACT DERMATITIS CLINICAL PERSPECTIVES AND BASIC MECHANISMS Abs: BIOSIS COPYRIGHT: BIOL ABS. RRM LITERATURE REVIEW HUMAN ALLERGY ECZEMA TOXICITY THERAPY PLANNING
1237457,Boscolo et al. 1996,The immunological effects of dust containing metals and compounds in workers of a plant producing plastic materials: Preliminary study,"BIOSIS COPYRIGHT: BIOL ABS. Lymphocyte subpopulations were studied in 14 men working in a plant producing plastic materials in comparison with a control group of similar age and smoking habit. The workers were exposed to dust containing particles of calcium carbonate, polyvinylchloride, phtalates, unsaturated oils, paraffin wax, iron oxides, titanium bioxides, barium, zinc, lead and lead chromate. In the exposed workers, T helper/ inducer lymphocytes (mainly CD4+-CD45RO- ""virgin"" lymphocytes) and CD19+ B lymphocytes were significantly reduced without changes of serum IgM, IgG and IgA. A highly significant correlation was found between B lymphocytes (reduced in the workers about 40%) and CD4+-CD45R0+ ""memory"" lymphocytes (reduced about 20 %). Moreover, blood lead (correlated with urinary chromium) demonstrated a highly significant negative correlation with B lymphocytes. This study demonstrates that combined exposure to toxic agents produces specific modifications in the lymphocyte subsets without","The immunological effects of dust containing metals and compounds in workers of a plant producing plastic materials: Preliminary study Abs: BIOSIS COPYRIGHT: BIOL ABS. Lymphocyte subpopulations were studied in 14 men working in a plant producing plastic materials in comparison with a control group of similar age and smoking habit. The workers were exposed to dust containing particles of calcium carbonate, polyvinylchloride, phtalates, unsaturated oils, paraffin wax, iron oxides, titanium bioxides, barium, zinc, lead and lead chromate. In the exposed workers, T helper/ inducer lymphocytes (mainly CD4+-CD45RO- ""virgin"" lymphocytes) and CD19+ B lymphocytes were significantly reduced without changes of serum IgM, IgG and IgA. A highly significant correlation was found between B lymphocytes (reduced in the workers about 40%) and CD4+-CD45R0+ ""memory"" lymphocytes (reduced about 20 %). Moreover, blood lead (correlated with urinary chromium) demonstrated a highly significant negative correlation with B lymphocytes. This study demonstrates that combined exposure to toxic agents produces specific modifications in the lymphocyte subsets without"
1237455,Itoh and  Shimada 1996,"Micronucleus induction by chromium and selenium, and suppression by metallothionein inducer","The clastogenic effects of chromium compounds (CrCl3 and K2CrO4) and selenium compounds (H2SeO3 and Na2SeO4) in mouse bone marrow cells have been investigated. K2CrO4 induced significant, dose-related increases in micronuclei. H2SeO3 also showed a significant micronucleus induction at the highest dose. CrCl3 and Na2SeO4 were negative for micronuclei induction in mice. The suppressive effect of Bi(NO3)3, a metallothionein inducer, on the micronucleus induction by K2CrO4 and H2SeO3 has been also investigated. Pretreatment with Bi(NO3)3 suppressed the micronucleus induction by K2CrO4 and H2SeO3. In addition, the incidence of micronucleus induction seemed to be reduced by double dosing with K2CrO4 and H2SeO3, compared to single dosing. It is generally recognized that a number of metal compounds induce metallothionein synthesis. These results suggest that the mechanism of suppression of micronucleus induction by K2CrO4 and H2SeO3 involve possible participation of metallothionein in mouse bone marrow.","Micronucleus induction by chromium and selenium, and suppression by metallothionein inducer Abs: The clastogenic effects of chromium compounds (CrCl3 and K2CrO4) and selenium compounds (H2SeO3 and Na2SeO4) in mouse bone marrow cells have been investigated. K2CrO4 induced significant, dose-related increases in micronuclei. H2SeO3 also showed a significant micronucleus induction at the highest dose. CrCl3 and Na2SeO4 were negative for micronuclei induction in mice. The suppressive effect of Bi(NO3)3, a metallothionein inducer, on the micronucleus induction by K2CrO4 and H2SeO3 has been also investigated. Pretreatment with Bi(NO3)3 suppressed the micronucleus induction by K2CrO4 and H2SeO3. In addition, the incidence of micronucleus induction seemed to be reduced by double dosing with K2CrO4 and H2SeO3, compared to single dosing. It is generally recognized that a number of metal compounds induce metallothionein synthesis. These results suggest that the mechanism of suppression of micronucleus induction by K2CrO4 and H2SeO3 involve possible participation of metallothionein in mouse bone marrow."
1237454,Ozbun et al. 1996,INCREASED LEVELS OF C-MYC MRNA IN LEAD CHROMATE AND 3-METHYL-CHOLANTHRENE TRANSFORMED 10T1-2 CELL LINES DUE TO ENHANCED STABILITY OF C-MYC MRNA,BIOSIS COPYRIGHT: BIOL ABS. RRM MEETING ABSTRACT MEETING POSTER HUMAN MOUSE EMBRYO FIBROBLAST CELL LINE 10T1-2 3-METHYLCHOLANTHRENE MESSENGER RNA TRANSCRIPTION RATE GENE EXPRESSION CARCINOGENESIS NEOPLASTIC TRANSFORMATION,INCREASED LEVELS OF C-MYC MRNA IN LEAD CHROMATE AND 3-METHYL-CHOLANTHRENE TRANSFORMED 10T1-2 CELL LINES DUE TO ENHANCED STABILITY OF C-MYC MRNA Abs: BIOSIS COPYRIGHT: BIOL ABS. RRM MEETING ABSTRACT MEETING POSTER HUMAN MOUSE EMBRYO FIBROBLAST CELL LINE 10T1-2 3-METHYLCHOLANTHRENE MESSENGER RNA TRANSCRIPTION RATE GENE EXPRESSION CARCINOGENESIS NEOPLASTIC TRANSFORMATION
1237450,Trenerry 1996,The determination of the sulphite content of some foods and beverages by capillary electrophoresis,"BIOSIS COPYRIGHT: BIOL ABS. A method for the determination of the sulphite content in foods and beverages by capillary electrophoresis (CE) is described. The sulphite is converted to sulphur dioxide and finally to sulphate using a Monier-Williams distillation. The sulphate is then determined by CE using a 75 mum fused silica capillary column with a buffer consisting of 5 mm sodium chromate and 0.5 mm OFM Anion-BT reagent, pH 8.0, with indirect UV detection at 254 nm. Nitrate was used as the internal standard. The levels of sulphite in the products are in good agreement with those determined by titrimetry, except for one sample of fresh prawns, fresh garlic and some processed foods containing garlic and onion, where the levels determined by CE are lower. The instrument repeatability of the CE procedure is satisfactory and the level of detection is 5 mg/kg.","The determination of the sulphite content of some foods and beverages by capillary electrophoresis Abs: BIOSIS COPYRIGHT: BIOL ABS. A method for the determination of the sulphite content in foods and beverages by capillary electrophoresis (CE) is described. The sulphite is converted to sulphur dioxide and finally to sulphate using a Monier-Williams distillation. The sulphate is then determined by CE using a 75 mum fused silica capillary column with a buffer consisting of 5 mm sodium chromate and 0.5 mm OFM Anion-BT reagent, pH 8.0, with indirect UV detection at 254 nm. Nitrate was used as the internal standard. The levels of sulphite in the products are in good agreement with those determined by titrimetry, except for one sample of fresh prawns, fresh garlic and some processed foods containing garlic and onion, where the levels determined by CE are lower. The instrument repeatability of the CE procedure is satisfactory and the level of detection is 5 mg/kg."
1237447,Roche and  Boge 1996,Fish blood parameters as a potential tool for identification of stress caused by environmental factors and chemical intoxication,"BIOSIS COPYRIGHT: BIOL ABS. Classical stress indicators (cortisol, glycemia, hemoglobin and hematocrit) and specific red blood cell responses of enzymes involved in protection against active oxygen species (superoxide dismutase (SOD), catalase and peroxidase activities) were investigated in sea bass (Dicentrarchus labrax) exposed to decreased salinity, increased temperature (physical stress) or to intoxication by metallic or organic compounds (chemical stress). Thermal stress led to a greater increase in glycemia, cortisol and peroxidase activity than osmotic shock, whereas SOD and catalase activities were more stimulated by osmotic shock. The most frequent responses of blood parameters to specific chemical intoxication involved peroxidase and MnSOD activities, and cortisolemia. Increased levels of cortisol were always found and were followed or not by enhanced glycemia. Pooling these results according to specific chemical families (metallic and organic compounds) revealed a low but general increa","Fish blood parameters as a potential tool for identification of stress caused by environmental factors and chemical intoxication Abs: BIOSIS COPYRIGHT: BIOL ABS. Classical stress indicators (cortisol, glycemia, hemoglobin and hematocrit) and specific red blood cell responses of enzymes involved in protection against active oxygen species (superoxide dismutase (SOD), catalase and peroxidase activities) were investigated in sea bass (Dicentrarchus labrax) exposed to decreased salinity, increased temperature (physical stress) or to intoxication by metallic or organic compounds (chemical stress). Thermal stress led to a greater increase in glycemia, cortisol and peroxidase activity than osmotic shock, whereas SOD and catalase activities were more stimulated by osmotic shock. The most frequent responses of blood parameters to specific chemical intoxication involved peroxidase and MnSOD activities, and cortisolemia. Increased levels of cortisol were always found and were followed or not by enhanced glycemia. Pooling these results according to specific chemical families (metallic and organic compounds) revealed a low but general increa"
1237446,Okrasinski and  Gul 1995,Allergic contact dermatitis in the Asir Region of Saudi Arabia: A pilot study,"BIOSIS COPYRIGHT: BIOL ABS. During the 16-month period from June 1993 to December 1994, 100 patients, Saudi nationals with suspected allergic contact dermatitis, were patch tested. True Test, containing a routine series of 24 test substances, was used at the dermatology clinics in the Military Hospitals in Khamis Mushayt, Saudi Arabia. The results showed that 30% of the patients with suspected allergic contact dermatitis were sensitive to one or more chemical substances used in the patch test. Nickel was the most common allergen in female patients (17.3%) and chromium was the most common in male patients (10.4%).","Allergic contact dermatitis in the Asir Region of Saudi Arabia: A pilot study Abs: BIOSIS COPYRIGHT: BIOL ABS. During the 16-month period from June 1993 to December 1994, 100 patients, Saudi nationals with suspected allergic contact dermatitis, were patch tested. True Test, containing a routine series of 24 test substances, was used at the dermatology clinics in the Military Hospitals in Khamis Mushayt, Saudi Arabia. The results showed that 30% of the patients with suspected allergic contact dermatitis were sensitive to one or more chemical substances used in the patch test. Nickel was the most common allergen in female patients (17.3%) and chromium was the most common in male patients (10.4%)."
1237445,Babu and  Shenolikar 1995,Health and nutritional implications of food colours,"BIOSIS COPYRIGHT: BIOL ABS. Colour is a vital constituent of food which imparts distinct appearance to the food product. Artificial colouring becomes a technological necessity as foods tend to lose their natural shade during processing and storage. Most of the food colours tested in the conventional toxicity experiments showed toxic effects at a very high level of intake i.e., 1-5 per cent in the diet. However, such levels of intake are not normally encountered. Human studies indicated that food colours (natural or synthetic) can induce wide range of allergic reactions only in sensitive or atopic individuals. Most of the foodborne diseases reported are due to the consumption of non-permitted textile colours or abuse of colours. The Government is pressurised periodically to place a total ban on the use of food colours due to their possible ill effects. It should be realised that surveillance should go hand in hand with legal actions.","Health and nutritional implications of food colours Abs: BIOSIS COPYRIGHT: BIOL ABS. Colour is a vital constituent of food which imparts distinct appearance to the food product. Artificial colouring becomes a technological necessity as foods tend to lose their natural shade during processing and storage. Most of the food colours tested in the conventional toxicity experiments showed toxic effects at a very high level of intake i.e., 1-5 per cent in the diet. However, such levels of intake are not normally encountered. Human studies indicated that food colours (natural or synthetic) can induce wide range of allergic reactions only in sensitive or atopic individuals. Most of the foodborne diseases reported are due to the consumption of non-permitted textile colours or abuse of colours. The Government is pressurised periodically to place a total ban on the use of food colours due to their possible ill effects. It should be realised that surveillance should go hand in hand with legal actions."
1237443,Thomulka and  Lange 1995,Use of the bioluminescent bacterium Vibrio harveyi to detect biohazardous chemicals in soil and water extractions with and without acid,"BIOSIS COPYRIGHT: BIOL ABS. An investigation was undertaken using the bioluminescence-reduction bioassay of Vibrio harveyi to study the toxicity of 31 chemicals in a soil and water extraction that was treated with and without hydrochloric acid. Soil had the chemical added and was washed with 0.2 N HCl and afterward this acid-treated soil containing the chemical was evaluated. Each chemical was tested independently. Endpoints determined were either an estimated effective concentration at 50 or 20%, which was based on bacterial-luminescence remaining after treatment. This investigation suggests that metals are more effectively bound in treatments without acid than those with acid, while no difference in toxicity was observed for organics. In comparison to a previous study of toxicity using these chemicals in water, soil was effective in reducing toxicity as determined by this assay. However, each chemical appears to have its own unique toxicity characteristic when evaluated under different condition","Use of the bioluminescent bacterium Vibrio harveyi to detect biohazardous chemicals in soil and water extractions with and without acid Abs: BIOSIS COPYRIGHT: BIOL ABS. An investigation was undertaken using the bioluminescence-reduction bioassay of Vibrio harveyi to study the toxicity of 31 chemicals in a soil and water extraction that was treated with and without hydrochloric acid. Soil had the chemical added and was washed with 0.2 N HCl and afterward this acid-treated soil containing the chemical was evaluated. Each chemical was tested independently. Endpoints determined were either an estimated effective concentration at 50 or 20%, which was based on bacterial-luminescence remaining after treatment. This investigation suggests that metals are more effectively bound in treatments without acid than those with acid, while no difference in toxicity was observed for organics. In comparison to a previous study of toxicity using these chemicals in water, soil was effective in reducing toxicity as determined by this assay. However, each chemical appears to have its own unique toxicity characteristic when evaluated under different condition"
1237442,Wang et al. 1995,Changes of the human erythrocyte membrane protein SH binding site property with exposure to fluoride and three strong mutagens,"BIOSIS COPYRIGHT: BIOL ABS. The effects of three strong mutagens (potassium bichromate, mitomycin C, and colchicine) and fluoride on the human erythrocyte membrane protein SH binding site property have been studied by using the maleimide nitroxide-ESR technique. The results indicate that in singular and combined treatments with mutagens, the ratio of weakly to strongly immobilized components is reduced, so that the conformation of the weakly immobilized component protein is altered. it is possible that the inhibition in the cytogenetic response is induced by the interaction of fluoride with the other chemicals. There is a dose and temperature dependence of both the singular and the combined action of the mutagen on the membrane protein.","Changes of the human erythrocyte membrane protein SH binding site property with exposure to fluoride and three strong mutagens Abs: BIOSIS COPYRIGHT: BIOL ABS. The effects of three strong mutagens (potassium bichromate, mitomycin C, and colchicine) and fluoride on the human erythrocyte membrane protein SH binding site property have been studied by using the maleimide nitroxide-ESR technique. The results indicate that in singular and combined treatments with mutagens, the ratio of weakly to strongly immobilized components is reduced, so that the conformation of the weakly immobilized component protein is altered. it is possible that the inhibition in the cytogenetic response is induced by the interaction of fluoride with the other chemicals. There is a dose and temperature dependence of both the singular and the combined action of the mutagen on the membrane protein."
1237440,Singh 1995,Haematological responses in a freshwater teleost Channa punctatus to experimental copper and chromium poisoning,"BIOSIS COPYRIGHT: BIOL ABS. The effect of copper sulfate and potassium dichromate poisoning on haematological parameters of a fresh water fish Channa punctatus has been studied. RBC, Hb%, PVC and MCHC values were significantly decreased while WBC, MCV and MCH were increased considerably upon treating the fish with both metallic compounds independently. Chromium proved more toxic than copper. Possible reasons for changes have been discussed.","Haematological responses in a freshwater teleost Channa punctatus to experimental copper and chromium poisoning Abs: BIOSIS COPYRIGHT: BIOL ABS. The effect of copper sulfate and potassium dichromate poisoning on haematological parameters of a fresh water fish Channa punctatus has been studied. RBC, Hb%, PVC and MCHC values were significantly decreased while WBC, MCV and MCH were increased considerably upon treating the fish with both metallic compounds independently. Chromium proved more toxic than copper. Possible reasons for changes have been discussed."
1237438,Freeman 1995,OCCUPATIONAL SKIN DISEASE,BIOSIS COPYRIGHT: BIOL ABS. RRM BOOK CHAPTER MEETING PAPER HUMAN CHEMICAL EXPOSURE TOXICITY,OCCUPATIONAL SKIN DISEASE Abs: BIOSIS COPYRIGHT: BIOL ABS. RRM BOOK CHAPTER MEETING PAPER HUMAN CHEMICAL EXPOSURE TOXICITY
1237434,Van Kasteren J and  Lotens 1995,Modelling and conceptual design of a waste smelting process,"BIOSIS COPYRIGHT: BIOL ABS. A pyrometallurgical process has been modelled and conceptually designed for the thermal treatment of heavy metal containing waste streams like MSW incinerator fly ash and sewage sludge. The modelling is carried out using the computer program EQUIMET as developed by Billiton Research BV. This program calculates thermodynamic equilibrium, making use of a slag model to account for the non-ideality of the slag phase. By comparison with a pilot test on smelting of MSW incinerator fly ash it is shown that thermodynamic modelling reasonably describes the waste smelting process and especially the fate of the minor elements. The thermodynamic model has been incorporated into a flow sheeting program, which calculates energy and mass balances for the proposed process configuration. Calculations show that it is possible to produce a clean slag phase, meeting recycling requirements. The heavy metal containing residues can be processed for further recycling.","Modelling and conceptual design of a waste smelting process Abs: BIOSIS COPYRIGHT: BIOL ABS. A pyrometallurgical process has been modelled and conceptually designed for the thermal treatment of heavy metal containing waste streams like MSW incinerator fly ash and sewage sludge. The modelling is carried out using the computer program EQUIMET as developed by Billiton Research BV. This program calculates thermodynamic equilibrium, making use of a slag model to account for the non-ideality of the slag phase. By comparison with a pilot test on smelting of MSW incinerator fly ash it is shown that thermodynamic modelling reasonably describes the waste smelting process and especially the fate of the minor elements. The thermodynamic model has been incorporated into a flow sheeting program, which calculates energy and mass balances for the proposed process configuration. Calculations show that it is possible to produce a clean slag phase, meeting recycling requirements. The heavy metal containing residues can be processed for further recycling."
1237433,Lui et al. 1995,Evaluation of metal ion toxicity on root tip cells by the Allium test,"BIOSIS COPYRIGHT: BIOL ABS. The effects of different concentrations of eleven different metals (aluminum chloride, chromium nitrate and potassium dichromate, lead nitrate, copper sulfate, manganous sulfate, cobaltous nitrate, zinc sulfate, magnesium sulfate, nickel sulfate, cadmium chloride, and mercuric chloride) on cell division and nucleoli in root tip cells of Allium cepa were studied. The results showed that the metal ions could, in varying degrees, cause chromosome, nucleus, and nucleolus irregularities, including c-mitosis, chromosome bridges, chromosome stickiness, irregularly shaped nuclei, micronuclei, irregularly shaped nucleoli, some silver-stained material scattered in the nucleus, the weakening of silver-staining reaction at the periphery of the nucleolus, and the release of nucleolar material from the nucleus into the cytoplasm. The Allium test may be useful for the rapid screening of chemicals involved in environmental problems.","Evaluation of metal ion toxicity on root tip cells by the Allium test Abs: BIOSIS COPYRIGHT: BIOL ABS. The effects of different concentrations of eleven different metals (aluminum chloride, chromium nitrate and potassium dichromate, lead nitrate, copper sulfate, manganous sulfate, cobaltous nitrate, zinc sulfate, magnesium sulfate, nickel sulfate, cadmium chloride, and mercuric chloride) on cell division and nucleoli in root tip cells of Allium cepa were studied. The results showed that the metal ions could, in varying degrees, cause chromosome, nucleus, and nucleolus irregularities, including c-mitosis, chromosome bridges, chromosome stickiness, irregularly shaped nuclei, micronuclei, irregularly shaped nucleoli, some silver-stained material scattered in the nucleus, the weakening of silver-staining reaction at the periphery of the nucleolus, and the release of nucleolar material from the nucleus into the cytoplasm. The Allium test may be useful for the rapid screening of chemicals involved in environmental problems."
1237431,Ruehl and  Kluger 1995,HAZARDOUS SUBSTANCES IN CONSTRUCTION WORK,BIOSIS COPYRIGHT: BIOL ABS. RRM LITERATURE REVIEW HUMAN CHEMICALS CARCINOGENS EMBRYOTOXINS NEUROTOXINS SKIN SENSITIZATION,HAZARDOUS SUBSTANCES IN CONSTRUCTION WORK Abs: BIOSIS COPYRIGHT: BIOL ABS. RRM LITERATURE REVIEW HUMAN CHEMICALS CARCINOGENS EMBRYOTOXINS NEUROTOXINS SKIN SENSITIZATION
1237429,Arensberg et al. 1995,A miniscale algal toxicity test,"BIOSIS COPYRIGHT: BIOL ABS. A simple miniscale (approx. 1 - 2.5 ml) toxicity test procedure with the freshwater green alga Selenastrum capricornutum is described. The procedure fulfils the validity criteria of the ISO (International Association for Standardization) standard test protocol. Practically identical concentration-response curves were obtained with the ISO standard test and the minitest for potassium dichromate and 3,5-dichlorophenol. The minitest is conveniently carried out using 2.5 ml test volume in 20 ml glass scintillation vials, placed on a microplate shaker or on an ordinary shaking table, but smaller containers and test volumes (down to 1 ml) could also be used. Tissue culture treated polystyrene microplates were found toxic to algae and thus unusable. pH control is achieved more easily in the minitest than in larger size shake flasks due to greater turbulence and a larger surface/volume ratio which both facilitates CO2 mass transfer. Uniform illumination of the individual units","A miniscale algal toxicity test Abs: BIOSIS COPYRIGHT: BIOL ABS. A simple miniscale (approx. 1 - 2.5 ml) toxicity test procedure with the freshwater green alga Selenastrum capricornutum is described. The procedure fulfils the validity criteria of the ISO (International Association for Standardization) standard test protocol. Practically identical concentration-response curves were obtained with the ISO standard test and the minitest for potassium dichromate and 3,5-dichlorophenol. The minitest is conveniently carried out using 2.5 ml test volume in 20 ml glass scintillation vials, placed on a microplate shaker or on an ordinary shaking table, but smaller containers and test volumes (down to 1 ml) could also be used. Tissue culture treated polystyrene microplates were found toxic to algae and thus unusable. pH control is achieved more easily in the minitest than in larger size shake flasks due to greater turbulence and a larger surface/volume ratio which both facilitates CO2 mass transfer. Uniform illumination of the individual units"
1237426,Codina et al. 1995,Comparison of microbial tests for the detection of heavy metal genotoxicity,"BIOSIS COPYRIGHT: BIOL ABS. Heavy metal genotoxicity was evaluated by using different microbial tests. Four genotoxicity assays were employed: the Ames test, the E. coli WP2 test, the Mutatox test detecting mutagenicity, and the SOS assay with E. coli-detecting enzyme induction. All the metals tested (cadmium, chromium, copper, mercury, nickel, and zinc) were detected as genotoxic by the Mutatox and the SOS tests. The Ames test and the E. coli WP2 assay only detected chromium as genotoxic, causing a mutagenic effect. The sensitivity to metals of all the assays used was maintained when they were dissolved in sewage, although there was a slight increase in the sensitivity thresholds.","Comparison of microbial tests for the detection of heavy metal genotoxicity Abs: BIOSIS COPYRIGHT: BIOL ABS. Heavy metal genotoxicity was evaluated by using different microbial tests. Four genotoxicity assays were employed: the Ames test, the E. coli WP2 test, the Mutatox test detecting mutagenicity, and the SOS assay with E. coli-detecting enzyme induction. All the metals tested (cadmium, chromium, copper, mercury, nickel, and zinc) were detected as genotoxic by the Mutatox and the SOS tests. The Ames test and the E. coli WP2 assay only detected chromium as genotoxic, causing a mutagenic effect. The sensitivity to metals of all the assays used was maintained when they were dissolved in sewage, although there was a slight increase in the sensitivity thresholds."
1237424,Keith et al. 1995,INTERACTION OF METALS DURING THEIR UPTAKE AND ACCUMULATION IN RABBIT RENAL CORTICAL SLICES,BIOSIS COPYRIGHT: BIOL ABS. RRM RESEARCH ARTICLE CADMIUM CHLORIDE MERCURIC CHLORIDE POTASSIUM DICHROMATE SODIUM ARSENITE RENAL TOXICITY PROTON-INDUCED X-RAY EMISSION,INTERACTION OF METALS DURING THEIR UPTAKE AND ACCUMULATION IN RABBIT RENAL CORTICAL SLICES Abs: BIOSIS COPYRIGHT: BIOL ABS. RRM RESEARCH ARTICLE CADMIUM CHLORIDE MERCURIC CHLORIDE POTASSIUM DICHROMATE SODIUM ARSENITE RENAL TOXICITY PROTON-INDUCED X-RAY EMISSION
1237421,Rajaram et al. 1995,Chromium(III) Induced Abnormalities in Human Lymphocyte cell Proliferation: Evidence for Apoptosis,"BIOSIS COPYRIGHT: BIOL ABS. The occupational hazards and respiratory problems of workers associated with the chromium related industries like mining, electroplating and tanning have received much focus. Although the cytotoxic and mutagenic effects of common chromium(VI) compounds are now established, to the best of our knowledge, this is the first report of apoptosis (programmed cell death) caused by a set of Cr(III) complexes in human lymphocyte cells. The effects of five Cr(III) complexes with differing ligand environment and structure as well as K2Cr2O7 on Phytohaemagglutinin (PHA) induced lymphocyte cell proliferation have been investigated. Two of the Cr(III) complexes and K2Cr2O7 are found to cause apoptosis of lymphocytes but not the others. A case for the importance of species specific effects rather than non specific metal oxidation state dependent processes has now been made.","Chromium(III) Induced Abnormalities in Human Lymphocyte cell Proliferation: Evidence for Apoptosis Abs: BIOSIS COPYRIGHT: BIOL ABS. The occupational hazards and respiratory problems of workers associated with the chromium related industries like mining, electroplating and tanning have received much focus. Although the cytotoxic and mutagenic effects of common chromium(VI) compounds are now established, to the best of our knowledge, this is the first report of apoptosis (programmed cell death) caused by a set of Cr(III) complexes in human lymphocyte cells. The effects of five Cr(III) complexes with differing ligand environment and structure as well as K2Cr2O7 on Phytohaemagglutinin (PHA) induced lymphocyte cell proliferation have been investigated. Two of the Cr(III) complexes and K2Cr2O7 are found to cause apoptosis of lymphocytes but not the others. A case for the importance of species specific effects rather than non specific metal oxidation state dependent processes has now been made."
1237417,Zhitkovich et al. 1995,GLUTATHIONE AND FREE AMINO ACIDS FORM STABLE ADDUCTS WITH DNA FOLLOWING EXPOSURE OF CHO CELLS TO CHROMATE,BIOSIS COPYRIGHT: BIOL ABS. RRM MEETING ABSTRACT MEETING POSTER CHINESE HAMSTER OVARY CELLS POTASSIUM CHROMATE CARCINOGEN,GLUTATHIONE AND FREE AMINO ACIDS FORM STABLE ADDUCTS WITH DNA FOLLOWING EXPOSURE OF CHO CELLS TO CHROMATE Abs: BIOSIS COPYRIGHT: BIOL ABS. RRM MEETING ABSTRACT MEETING POSTER CHINESE HAMSTER OVARY CELLS POTASSIUM CHROMATE CARCINOGEN
1237416,Agner 1995,CONTACT DERMATITIS,BIOSIS COPYRIGHT: BIOL ABS. RRM BOOK CHAPTER HUMAN ANTIINFLAMMATORY DRUGS MOISTURIZERS IRRITANTS OCCUPATIONAL DERMATITIS SKIN REACTIVITY DOSE-RESPONSE STUDIES UV IRRADIATION CLINICAL ASSESSMENT LASER DOPPLER FLOWMETRY METHODOLOGY,CONTACT DERMATITIS Abs: BIOSIS COPYRIGHT: BIOL ABS. RRM BOOK CHAPTER HUMAN ANTIINFLAMMATORY DRUGS MOISTURIZERS IRRITANTS OCCUPATIONAL DERMATITIS SKIN REACTIVITY DOSE-RESPONSE STUDIES UV IRRADIATION CLINICAL ASSESSMENT LASER DOPPLER FLOWMETRY METHODOLOGY
1237414,Sontz and  Schwieger 1995,THE GREEN WATER SYNDROME COPPER-INDUCED HEMOLYSIS AND SUBSEQUENT ACUTE RENAL FAILURE AS CONSEQUENCE OF A RELIGIOUS RITUAL,BIOSIS COPYRIGHT: BIOL ABS. RRM CASE STUDY HUMAN CLINICAL PRESENTATION COPPER TOXICITY DIAGNOSIS THERAPY,THE GREEN WATER SYNDROME COPPER-INDUCED HEMOLYSIS AND SUBSEQUENT ACUTE RENAL FAILURE AS CONSEQUENCE OF A RELIGIOUS RITUAL Abs: BIOSIS COPYRIGHT: BIOL ABS. RRM CASE STUDY HUMAN CLINICAL PRESENTATION COPPER TOXICITY DIAGNOSIS THERAPY
1237405,Westlake et al. 1994,BEHAVIOURAL RESPONSES OF RAINBOW TROUT TO INDUSTRIAL EFFLUENTS,BIOSIS COPYRIGHT: BIOL ABS. RRM MEETING ABSTRACT ONCORHYNCHUS-MYKISS FISH COPPER SODIUM LIGNOSULFONATE ABIETIC ACID POTASSIUM CHROMATE GUAIACOL P-CHLOROPHENOL TOXICITY WATER POLLUTION BEHAVIOR LOCOMOTOR RESPONSE,BEHAVIOURAL RESPONSES OF RAINBOW TROUT TO INDUSTRIAL EFFLUENTS Abs: BIOSIS COPYRIGHT: BIOL ABS. RRM MEETING ABSTRACT ONCORHYNCHUS-MYKISS FISH COPPER SODIUM LIGNOSULFONATE ABIETIC ACID POTASSIUM CHROMATE GUAIACOL P-CHLOROPHENOL TOXICITY WATER POLLUTION BEHAVIOR LOCOMOTOR RESPONSE
1237404,Sloterdijk et al. 1994,FISH AS INDICATORS OF HEAVY METAL POLLUTION IN THE ST. LAWRENCE RIVER,BIOSIS COPYRIGHT: BIOL ABS. RRM MEETING ABSTRACT NOTROPIS-HUDSONIUS PERCA-FLAVESCENS CATOSTOMUS-COMMERSONI MERCURY CADMIUM LEAD CHROMATE NICKEL COPPER ZINC METALLOTHIONEIN BIOACCUMULATION SOIL POLLUTION WATER POLLUTION SEDIMENT CONTAMINATION,FISH AS INDICATORS OF HEAVY METAL POLLUTION IN THE ST. LAWRENCE RIVER Abs: BIOSIS COPYRIGHT: BIOL ABS. RRM MEETING ABSTRACT NOTROPIS-HUDSONIUS PERCA-FLAVESCENS CATOSTOMUS-COMMERSONI MERCURY CADMIUM LEAD CHROMATE NICKEL COPPER ZINC METALLOTHIONEIN BIOACCUMULATION SOIL POLLUTION WATER POLLUTION SEDIMENT CONTAMINATION
1237402,Dews et al. 1994,ENHANCED STABILITY OF C-MYC RNA CONTRIBUTES TO INCREASED STEADY-STATE LEVELS OF C-MYC RNA IN TRANSFORMED C3H-10T1-2 MOUSE EMBRYO CELL LINES INDUCED BY LEAD CHROMATE,BIOSIS COPYRIGHT: BIOL ABS. RRM MEETING POSTER MEETING ABSTRACT NEOPLASTIC TRANSFORMATION TRANSCRIPTION,ENHANCED STABILITY OF C-MYC RNA CONTRIBUTES TO INCREASED STEADY-STATE LEVELS OF C-MYC RNA IN TRANSFORMED C3H-10T1-2 MOUSE EMBRYO CELL LINES INDUCED BY LEAD CHROMATE Abs: BIOSIS COPYRIGHT: BIOL ABS. RRM MEETING POSTER MEETING ABSTRACT NEOPLASTIC TRANSFORMATION TRANSCRIPTION
1237401,Goh and  Yuen 1994,A STUDY OF OCCUPATIONAL SKIN DISEASE IN THE METAL INDUSTRY 1986-1990,BIOSIS COPYRIGHT: BIOL ABS. RRM RESEARCH ARTICLE HUMAN ATOPY CONTACT DERMATITIS,A STUDY OF OCCUPATIONAL SKIN DISEASE IN THE METAL INDUSTRY 1986-1990 Abs: BIOSIS COPYRIGHT: BIOL ABS. RRM RESEARCH ARTICLE HUMAN ATOPY CONTACT DERMATITIS
1237400,Y-C et al. 1994,SURFACTANT-ENHANCED ULTRAFILTRATION OF HEAVY METALS FROM WASTE STREAMS WITH PILOT-SCALE SYSTEM,BIOSIS COPYRIGHT: BIOL ABS. RRM RESEARCH ARTICLE CADMIUM LEAD COPPER NICKEL ZINC CHROMATE DEOXYCHOLIC ACID INDUSTRIAL WASTEWATER TREATMENT WASTE MANAGEMENT MEMBRANE SYSTEM,SURFACTANT-ENHANCED ULTRAFILTRATION OF HEAVY METALS FROM WASTE STREAMS WITH PILOT-SCALE SYSTEM Abs: BIOSIS COPYRIGHT: BIOL ABS. RRM RESEARCH ARTICLE CADMIUM LEAD COPPER NICKEL ZINC CHROMATE DEOXYCHOLIC ACID INDUSTRIAL WASTEWATER TREATMENT WASTE MANAGEMENT MEMBRANE SYSTEM
1237397,Zelikoff 1994,FISH IMMUNOTOXICOLOGY,BIOSIS COPYRIGHT: BIOL ABS. RRM BOOK CHAPTER AQUATIC TOXIC CONTAMINANTS ENVIRONMENTAL POLLUTION IMMUNOSUPPRESSION HUMORAL IMMUNITY CELL-MEDIATED IMMUNITY DISEASE RESISTANCE FISH HATCHERY FISH INDUSTRY USA,FISH IMMUNOTOXICOLOGY Abs: BIOSIS COPYRIGHT: BIOL ABS. RRM BOOK CHAPTER AQUATIC TOXIC CONTAMINANTS ENVIRONMENTAL POLLUTION IMMUNOSUPPRESSION HUMORAL IMMUNITY CELL-MEDIATED IMMUNITY DISEASE RESISTANCE FISH HATCHERY FISH INDUSTRY USA
1237395,Toffoletto et al. 1994,OCCUPATIONAL CONTACT DERMATITIS FROM AMINE-FUNCTIONAL METHOXYSILANE IN CONTINUOUS-GLASS-FILAMENT PRODUCTION,BIOSIS COPYRIGHT: BIOL ABS. RRM RESEARCH ARTICLE HUMAN SKIN CONTACT ALLERGY CONTACT DERMATITIS OCCUPATIONAL HEALTH AND SAFETY ALLERGENS GLOVE USE,OCCUPATIONAL CONTACT DERMATITIS FROM AMINE-FUNCTIONAL METHOXYSILANE IN CONTINUOUS-GLASS-FILAMENT PRODUCTION Abs: BIOSIS COPYRIGHT: BIOL ABS. RRM RESEARCH ARTICLE HUMAN SKIN CONTACT ALLERGY CONTACT DERMATITIS OCCUPATIONAL HEALTH AND SAFETY ALLERGENS GLOVE USE
1237393,Hilton et al. 1994,Interleukin 6 production in vitro: An alternative read-out for the local lymph node assay,"BIOSIS COPYRIGHT: BIOL ABS. The murine local lymph node assay has been developed as an alternative method for the identification of contact allergens. In contrast to guinea pig tests, which rely on visual assessment of challenge-induced dermal reactions, the local lymph node assay measures events occurring during the induction of skin sensitization. Contact allergic potential is measured as a function of hyperplastic responses in draining lymph nodes following systemic administration of (3H)thymidine. We have now examined whether the production in vitro of interleukin 6 (IL-6) by draining lymph node cells isolated from sensitized mice provides an alternative endpoint for the local lymph node assay. In comparative experiments, the production of IL-6 by lymph node cells in culture correlated closely with proliferative responses in vitro. Only chemicals known to cause contact sensitization elicited measurable (> 150 pg/ml) IL-6 production; non-sensitizing chemicals, including skin irritants, did n","Interleukin 6 production in vitro: An alternative read-out for the local lymph node assay Abs: BIOSIS COPYRIGHT: BIOL ABS. The murine local lymph node assay has been developed as an alternative method for the identification of contact allergens. In contrast to guinea pig tests, which rely on visual assessment of challenge-induced dermal reactions, the local lymph node assay measures events occurring during the induction of skin sensitization. Contact allergic potential is measured as a function of hyperplastic responses in draining lymph nodes following systemic administration of (3H)thymidine. We have now examined whether the production in vitro of interleukin 6 (IL-6) by draining lymph node cells isolated from sensitized mice provides an alternative endpoint for the local lymph node assay. In comparative experiments, the production of IL-6 by lymph node cells in culture correlated closely with proliferative responses in vitro. Only chemicals known to cause contact sensitization elicited measurable (> 150 pg/ml) IL-6 production; non-sensitizing chemicals, including skin irritants, did n"
1237391,Davis and  Arnold 1994,Estimation of apparent phosphorus availability from inorganic phosphorus sources for Penaeus vannamei,"BIOSIS COPYRIGHT: BIOL ABS. The determination of net phosphorus absorption (apparent phosphorus availability, APA) from various feedstuffs by shrimp and the leaching losses from feeds are required for the evaluation of nutrient sources in terms of their nutritional, economic and environmental impacts. Utilizing chromic oxide as an inert marker, APA for inorganic phosphorus sources and the effects of calcium supplements on APA were evaluated in Penaeus vannamei. Based on the results of the present study, the following APA values were determined: calcium phosphate monobasic, 46.3%; calcium phosphate dibasic, 19.1%; calcium phosphate tribasic, 9.9%; potassium phosphate monobasic, 68.1%; sodium phosphate monobasic, 68.2%. APA values for diets utilizing sodium phosphate monobasic as the phosphorus source were significantly depressed by the presence of calcium lactate (50.0% APA) but not by calcium carbonate (65.5% APA) or calcium chloride (68.2% APA). Although leaching losses for some of the test diets","Estimation of apparent phosphorus availability from inorganic phosphorus sources for Penaeus vannamei Abs: BIOSIS COPYRIGHT: BIOL ABS. The determination of net phosphorus absorption (apparent phosphorus availability, APA) from various feedstuffs by shrimp and the leaching losses from feeds are required for the evaluation of nutrient sources in terms of their nutritional, economic and environmental impacts. Utilizing chromic oxide as an inert marker, APA for inorganic phosphorus sources and the effects of calcium supplements on APA were evaluated in Penaeus vannamei. Based on the results of the present study, the following APA values were determined: calcium phosphate monobasic, 46.3%; calcium phosphate dibasic, 19.1%; calcium phosphate tribasic, 9.9%; potassium phosphate monobasic, 68.1%; sodium phosphate monobasic, 68.2%. APA values for diets utilizing sodium phosphate monobasic as the phosphorus source were significantly depressed by the presence of calcium lactate (50.0% APA) but not by calcium carbonate (65.5% APA) or calcium chloride (68.2% APA). Although leaching losses for some of the test diets"
1237390,Maurer et al. 1994,Guinea pig contact sensitization assays,"BIOSIS COPYRIGHT: BIOL ABS. After reviewing general aspects and the historical development of predictive animal skin sensitization tests, the recommended tests of the OECD and EC are discussed. Background information is given on the changes which occurred in the last 2 years. From the many factors known to influence induction and challenge of contact allergy in animals, the discussion is focused on the choice of induction concentration and the vehicle. The difference of general screening strategies in Europe and the USA is presented and discussed. The paper closes with a discussion on the importance of inhouse validation of the methods used for proper prediction of the sensitizing potential of chemicals and with remarks on predictive in vitro tests.","Guinea pig contact sensitization assays Abs: BIOSIS COPYRIGHT: BIOL ABS. After reviewing general aspects and the historical development of predictive animal skin sensitization tests, the recommended tests of the OECD and EC are discussed. Background information is given on the changes which occurred in the last 2 years. From the many factors known to influence induction and challenge of contact allergy in animals, the discussion is focused on the choice of induction concentration and the vehicle. The difference of general screening strategies in Europe and the USA is presented and discussed. The paper closes with a discussion on the importance of inhouse validation of the methods used for proper prediction of the sensitizing potential of chemicals and with remarks on predictive in vitro tests."
1237389,Kimber et al. 1994,The local lymph node assay: Developments and applications,BIOSIS COPYRIGHT: BIOL ABS. The murine local lymph node assay is a predictive test method for the identification of contact allergens in which sensitizing activity is measured as a function of induced proliferative responses in lymph nodes draining the site of application. In this article the development and validation of the assay are described and comparisons with guinea pig predictive test methods discussed. In addition we examine the advantages and limitations of the method and consider new opportunities and applications of the assay in the context of the toxicological evaluation of sensitizing potential.,The local lymph node assay: Developments and applications Abs: BIOSIS COPYRIGHT: BIOL ABS. The murine local lymph node assay is a predictive test method for the identification of contact allergens in which sensitizing activity is measured as a function of induced proliferative responses in lymph nodes draining the site of application. In this article the development and validation of the assay are described and comparisons with guinea pig predictive test methods discussed. In addition we examine the advantages and limitations of the method and consider new opportunities and applications of the assay in the context of the toxicological evaluation of sensitizing potential.
1237387,Maurer et al. 1994,Contact hypersensitivity: Animal tests,"BIOSIS COPYRIGHT: BIOL ABS. After reviewing general aspects and the historical development of predictive animal skin sensitization tests, the recommended tests of the OECD and EC are discussed. Background information is given on the changes that have occurred during the last 2 yr. Although many factors are known to influence induction and elicitation of contact allergy in animals, the discussion is focused on the choice of induction concentration and the vehicle. Differences in general screening strategies between Europe and the USA are considered. The paper concludes with a discussion about the importance of in-house validation of the methods used for proper prediction of the sensitizing potential of chemicals and with remarks on predictive in vitro tests.","Contact hypersensitivity: Animal tests Abs: BIOSIS COPYRIGHT: BIOL ABS. After reviewing general aspects and the historical development of predictive animal skin sensitization tests, the recommended tests of the OECD and EC are discussed. Background information is given on the changes that have occurred during the last 2 yr. Although many factors are known to influence induction and elicitation of contact allergy in animals, the discussion is focused on the choice of induction concentration and the vehicle. Differences in general screening strategies between Europe and the USA are considered. The paper concludes with a discussion about the importance of in-house validation of the methods used for proper prediction of the sensitizing potential of chemicals and with remarks on predictive in vitro tests."
1237385,Crisinel et al. 1994,Cyst-based ecotoxicological tests using anostracans: Comparison of two species of Streptocephalus,"BIOSIS COPYRIGHT: BIOL ABS. Cyst-based ecotoxicological tests are simple and low-cost methods for assessing acute toxicity. Nevertheless, only a few comparative studies on their sensitivity are known. In the present study, the suitability of the use of two freshwater Anostracan species, Streptocephalus rubricaudatus and S. texanus, was assessed. The impact of 16 priority pollutants (4 heavy metals, 11 organic, and 1 organometallic compounds) on these two species, as well as on Artemia salina (Artoxkit M), Daphnia magna (International Organization for Standardization 6341), and S. proboscideus (Streptoxkit F) was assessed. For indicative comparison, bioassays using Brachionus calyciflorus (Rotoxkit F) and Photobacterium phosphoreum (Microtox) were also performed. For heavy metals (K2Cr2O7, Cd2+, Zn2+, Cu2+), the sensitivity of the two studied Streptocephalus species was slightly higher than that of D. magna. It was significantly more elevated than for the marine A. salina. For organic and organomet","Cyst-based ecotoxicological tests using anostracans: Comparison of two species of Streptocephalus Abs: BIOSIS COPYRIGHT: BIOL ABS. Cyst-based ecotoxicological tests are simple and low-cost methods for assessing acute toxicity. Nevertheless, only a few comparative studies on their sensitivity are known. In the present study, the suitability of the use of two freshwater Anostracan species, Streptocephalus rubricaudatus and S. texanus, was assessed. The impact of 16 priority pollutants (4 heavy metals, 11 organic, and 1 organometallic compounds) on these two species, as well as on Artemia salina (Artoxkit M), Daphnia magna (International Organization for Standardization 6341), and S. proboscideus (Streptoxkit F) was assessed. For indicative comparison, bioassays using Brachionus calyciflorus (Rotoxkit F) and Photobacterium phosphoreum (Microtox) were also performed. For heavy metals (K2Cr2O7, Cd2+, Zn2+, Cu2+), the sensitivity of the two studied Streptocephalus species was slightly higher than that of D. magna. It was significantly more elevated than for the marine A. salina. For organic and organomet"
1237382,Lee 1994,THE OCCUPATIONAL HISTORY,BIOSIS COPYRIGHT: BIOL ABS. RRM BOOK CHAPTER HUMAN DIAGNOSIS TOXIC HAZARDS,THE OCCUPATIONAL HISTORY Abs: BIOSIS COPYRIGHT: BIOL ABS. RRM BOOK CHAPTER HUMAN DIAGNOSIS TOXIC HAZARDS
1237377,Chorvatovicova and  Kovacikova 1993,Combined effects of hexavalent chromium and organomercurial in mice,BIOSIS COPYRIGHT: BIOL ABS. The simultaneous administration of potassium bichromate and O-hydroxymercuribenzoic acid anhydride (organomercurial) in female ICR mice was studied. The chemicals were injected intraperitoneally 24 hours before sacrifice and micronuclei frequencies in bone marrow and transaminase activities in the liver were examined. The results of micronucleus test confirmed that in the case of combined exposure to hexavalent chromium and organomercurial a synergic action on micronuclei frequency in polychromatic erythrocytes of bone marrow was involved. The transaminases were elevated only after bichromate application. Combined application of both studied compounds did not elevate the activity anymore. The results draw attention to the possible additive genotoxic hazard of combined exposure to hexavalent chromium and organomercurial.,Combined effects of hexavalent chromium and organomercurial in mice Abs: BIOSIS COPYRIGHT: BIOL ABS. The simultaneous administration of potassium bichromate and O-hydroxymercuribenzoic acid anhydride (organomercurial) in female ICR mice was studied. The chemicals were injected intraperitoneally 24 hours before sacrifice and micronuclei frequencies in bone marrow and transaminase activities in the liver were examined. The results of micronucleus test confirmed that in the case of combined exposure to hexavalent chromium and organomercurial a synergic action on micronuclei frequency in polychromatic erythrocytes of bone marrow was involved. The transaminases were elevated only after bichromate application. Combined application of both studied compounds did not elevate the activity anymore. The results draw attention to the possible additive genotoxic hazard of combined exposure to hexavalent chromium and organomercurial.
1237373,Dews et al. 1994,INCREASED STEADY-STATE LEVELS OF C-MYC RNA IN TRANSFORMED 10T1-2 MOUSE EMBRYO CELL LINES INDUCED BY LEAD CHROMATE,BIOSIS COPYRIGHT: BIOL ABS. RRM MEETING ABSTRACT CARCINOGEN CARCINOGENESIS,INCREASED STEADY-STATE LEVELS OF C-MYC RNA IN TRANSFORMED 10T1-2 MOUSE EMBRYO CELL LINES INDUCED BY LEAD CHROMATE Abs: BIOSIS COPYRIGHT: BIOL ABS. RRM MEETING ABSTRACT CARCINOGEN CARCINOGENESIS
1237372,Appenroth et al. 1994,EFFECT OF ASCORBIC ACID ON CHROMATE INDUCED NEPHROTOXICITY IN RATS,BIOSIS COPYRIGHT: BIOL ABS. RRM MEETING ABSTRACT INDUSTRIAL TOXIN CELLULAR REDUCTION PROTEINURIA RADICAL SCAVENGING EFFECT SODIUM CHROMATE,EFFECT OF ASCORBIC ACID ON CHROMATE INDUCED NEPHROTOXICITY IN RATS Abs: BIOSIS COPYRIGHT: BIOL ABS. RRM MEETING ABSTRACT INDUSTRIAL TOXIN CELLULAR REDUCTION PROTEINURIA RADICAL SCAVENGING EFFECT SODIUM CHROMATE
1237370,Weerasena O V D et al. 1993,Fungicidal activity of synthetically modified cashew nut shell liquid,BIOSIS COPYRIGHT: BIOL ABS. Three synthetic modifications of cashew nut shell liquid were prepared with a view of increasing its mild fungicidal activity. Of these the potassium dichromate oxidized cashew nut shell liquid showed the highest activity in the tlc-Cladosporium bio-assay. The oxidized product inhibited the growth of several fungal plant pathogens examined. The active compound was isolated by silica gel column chromatography and identified as a biodegradable quinone produced by the aromatic ring oxidation of cardol.,Fungicidal activity of synthetically modified cashew nut shell liquid Abs: BIOSIS COPYRIGHT: BIOL ABS. Three synthetic modifications of cashew nut shell liquid were prepared with a view of increasing its mild fungicidal activity. Of these the potassium dichromate oxidized cashew nut shell liquid showed the highest activity in the tlc-Cladosporium bio-assay. The oxidized product inhibited the growth of several fungal plant pathogens examined. The active compound was isolated by silica gel column chromatography and identified as a biodegradable quinone produced by the aromatic ring oxidation of cardol.
1237368,Omer and  Al-Tawil 1994,CONTACT SENSITIVITY AMONG WORKERS IN A PAINT FACTORY,BIOSIS COPYRIGHT: BIOL ABS. RRM NOTE HUMAN ALLERGIC CONTACT DERMATITIS POTASSIUM DICHROMATE ETHYLENEDIAMINE COBALT CHLORIDE PHENOL-FORMALDEHYDE RESIN HEALTH HAZARD,CONTACT SENSITIVITY AMONG WORKERS IN A PAINT FACTORY Abs: BIOSIS COPYRIGHT: BIOL ABS. RRM NOTE HUMAN ALLERGIC CONTACT DERMATITIS POTASSIUM DICHROMATE ETHYLENEDIAMINE COBALT CHLORIDE PHENOL-FORMALDEHYDE RESIN HEALTH HAZARD
1237361,Merlin et al. 1993,USE OF FLUORESCENCE INDUCTION KINETICS OF LEMNA MINOR AS A TOOL FOR CHEMICAL STRESS EVALUATION,BIOSIS COPYRIGHT: BIOL ABS. RRM RESEARCH ARTICLE LEMNA-MINOR PHOTOSYNTHESIS ECOTOXICOLOGY ENVIRONMENTAL POLLUTION TOXICITY TESTING,USE OF FLUORESCENCE INDUCTION KINETICS OF LEMNA MINOR AS A TOOL FOR CHEMICAL STRESS EVALUATION Abs: BIOSIS COPYRIGHT: BIOL ABS. RRM RESEARCH ARTICLE LEMNA-MINOR PHOTOSYNTHESIS ECOTOXICOLOGY ENVIRONMENTAL POLLUTION TOXICITY TESTING
1237359,Chen and  Thilly 1994,Mutational spectrum of chromium(VI) in human cells,"BIOSIS COPYRIGHT: BIOL ABS. The mutational spectrum of K2Cr2O7 on the low melting domain within exon 3 of hypoxanthine guanine phosphoribosyl transferase (hprt) gene was obtained from 6-thioguanine-resistant (6TGr) human lymphoblasts (TK6). Using a combination of high-fidelity polymerase chain reaction (PCR) and denaturing gradient gel electrophoresis (DGGE), we found four chromium(VI) induced hotspots in a 104-bp target sequence. The hotspots were C:G - A:T at bp 243, representing 4.5% of 6TGr mutants; A:T - T:A at bp 247 (2.0%); G:C - A:T at hp 289 (2.5%) and C:G - T:A at bp 312 (4.0%). Mutational hotspots at bp 243 have previously been determined for hydrogen peroxide (C:G - G:C) and benzo(a)pyrene diol epoxide (C:G - A:T). Two of the hotspots, bp 243 and 289, arose in a common quadruplet 5'-ACAT-3' in the untranscribed and transcribed strands respectively.","Mutational spectrum of chromium(VI) in human cells Abs: BIOSIS COPYRIGHT: BIOL ABS. The mutational spectrum of K2Cr2O7 on the low melting domain within exon 3 of hypoxanthine guanine phosphoribosyl transferase (hprt) gene was obtained from 6-thioguanine-resistant (6TGr) human lymphoblasts (TK6). Using a combination of high-fidelity polymerase chain reaction (PCR) and denaturing gradient gel electrophoresis (DGGE), we found four chromium(VI) induced hotspots in a 104-bp target sequence. The hotspots were C:G - A:T at bp 243, representing 4.5% of 6TGr mutants; A:T - T:A at bp 247 (2.0%); G:C - A:T at hp 289 (2.5%) and C:G - T:A at bp 312 (4.0%). Mutational hotspots at bp 243 have previously been determined for hydrogen peroxide (C:G - G:C) and benzo(a)pyrene diol epoxide (C:G - A:T). Two of the hotspots, bp 243 and 289, arose in a common quadruplet 5'-ACAT-3' in the untranscribed and transcribed strands respectively."
1237358,Igarashi and  Shimada 1993,PRACTICAL METHOD OF THE LIVER MICRONUCLEUS TEST IN MOUSE,BIOSIS COPYRIGHT: BIOL ABS. RRM MEETING PAPER MITOMYCIN C CYCLOPHOSPHAMIDE N-ETHYL-N-NITROSOUREA DIETHYLNITROSOAMINE 4-DIMETHYLAMINO-3'-METHYLAZOBENZENE 2-ACETYLAMINOFLUORENE BENZENE POTASSIUM CHROMATE SELENIOUS ACID FORMULAS LIVER CLASTOGENS SCREENING TEST,PRACTICAL METHOD OF THE LIVER MICRONUCLEUS TEST IN MOUSE Abs: BIOSIS COPYRIGHT: BIOL ABS. RRM MEETING PAPER MITOMYCIN C CYCLOPHOSPHAMIDE N-ETHYL-N-NITROSOUREA DIETHYLNITROSOAMINE 4-DIMETHYLAMINO-3'-METHYLAZOBENZENE 2-ACETYLAMINOFLUORENE BENZENE POTASSIUM CHROMATE SELENIOUS ACID FORMULAS LIVER CLASTOGENS SCREENING TEST
1237357,Peterson 1993,TOXIC PYROLYSIS PRODUCTS OF SOLVENTS PAINTS AND POLYMER FILMS,BIOSIS COPYRIGHT: BIOL ABS. RRM LITERATURE REVIEW HUMAN OCCUPATIONAL HEALTH,TOXIC PYROLYSIS PRODUCTS OF SOLVENTS PAINTS AND POLYMER FILMS Abs: BIOSIS COPYRIGHT: BIOL ABS. RRM LITERATURE REVIEW HUMAN OCCUPATIONAL HEALTH
1237356,Reda and  Alhajji 1993,INVESTIGATION OF THE EFFECT OF PRE-EXPOSURE TO SOME EXTRANEOUS IONS ON THE CORROSION OF COPPER-NICKEL ALLOYS IN SULFIDE-POLLUTED ARTIFICIAL SEAWATER,BIOSIS COPYRIGHT: BIOL ABS. RRM RESEARCH ARTICLE POTASSIUM CHROMATE SODIUM MOLYBDATE,INVESTIGATION OF THE EFFECT OF PRE-EXPOSURE TO SOME EXTRANEOUS IONS ON THE CORROSION OF COPPER-NICKEL ALLOYS IN SULFIDE-POLLUTED ARTIFICIAL SEAWATER Abs: BIOSIS COPYRIGHT: BIOL ABS. RRM RESEARCH ARTICLE POTASSIUM CHROMATE SODIUM MOLYBDATE
1237354,Centeno M et al. 1993,Acute toxicity tests with Streptocephalus proboscideus (Crustacea: Branchiopoda: Anostraca): Influence of selected environmental conditions,"BIOSIS COPYRIGHT: BIOL ABS. The influence of selected environmental conditions on the acute toxicity of 3 selected chemicals (K2Cr2O7, CuSO4 and Na pentachlorophenate) to instar II-III larvae of Streptocephalus proboscideus was evaluated. Mortality after a 24-h incubation was used as effect criterion. Factorial experiments were set up resulting to 25 different combinations of temperature and water hardness. The effects of pH of the dilution medium and light regime during toxicant exposure were also assessed. Results (24-h LC50's) from nearly 200 tests revealed that the degree of variation is chemical- and test condition-dependent. Water hardness had the greatest effect on larval sensitivity, showing a significant (p 0.05) negative correlation. A significant effect (p 0.05) on sensitivity was furthermore detected only for the extreme values of temperature (30? C) and pH (6.0) tested. Light conditions during acute exposure caused no change in larval sensitivity.","Acute toxicity tests with Streptocephalus proboscideus (Crustacea: Branchiopoda: Anostraca): Influence of selected environmental conditions Abs: BIOSIS COPYRIGHT: BIOL ABS. The influence of selected environmental conditions on the acute toxicity of 3 selected chemicals (K2Cr2O7, CuSO4 and Na pentachlorophenate) to instar II-III larvae of Streptocephalus proboscideus was evaluated. Mortality after a 24-h incubation was used as effect criterion. Factorial experiments were set up resulting to 25 different combinations of temperature and water hardness. The effects of pH of the dilution medium and light regime during toxicant exposure were also assessed. Results (24-h LC50's) from nearly 200 tests revealed that the degree of variation is chemical- and test condition-dependent. Water hardness had the greatest effect on larval sensitivity, showing a significant (p 0.05) negative correlation. A significant effect (p 0.05) on sensitivity was furthermore detected only for the extreme values of temperature (30? C) and pH (6.0) tested. Light conditions during acute exposure caused no change in larval sensitivity."
1237352,Thomulka et al. 1993,Detection of biohazardous materials in water by measuring bioluminescence reduction with the marine organism Vibrio harveyi,"BIOSIS COPYRIGHT: BIOL ABS. This study evaluated two bioassay methods, direct and growth, using Vibrio harveyi, a bioluminescent bacterium, to detect biohazardous materials in water. The end point measured for the evaluation of the toxicity of the various substances tested was the median effective concentration for bioluminescence reduction. Thirty-four compounds were tested, including representatives from the following chemical categories: azide, alcohols, antibiotics, antioxidants, detergents, formalin, heavy metals, oxidants and peroxide. While the direct and growth assays were unable to identify toxicity in seventeen and seven compounds, respectively, they appear to be more sensitive than the Microtox assay system. The use of these assay methods for monitoring and evaluating aquatic environments is discussed.","Detection of biohazardous materials in water by measuring bioluminescence reduction with the marine organism Vibrio harveyi Abs: BIOSIS COPYRIGHT: BIOL ABS. This study evaluated two bioassay methods, direct and growth, using Vibrio harveyi, a bioluminescent bacterium, to detect biohazardous materials in water. The end point measured for the evaluation of the toxicity of the various substances tested was the median effective concentration for bioluminescence reduction. Thirty-four compounds were tested, including representatives from the following chemical categories: azide, alcohols, antibiotics, antioxidants, detergents, formalin, heavy metals, oxidants and peroxide. While the direct and growth assays were unable to identify toxicity in seventeen and seven compounds, respectively, they appear to be more sensitive than the Microtox assay system. The use of these assay methods for monitoring and evaluating aquatic environments is discussed."
1237347,Lowe et al. 1993,ELEMENTAL ANALYSIS OF RENAL SLICES BY PROTON-INDUCED X-RAY EMISSION,BIOSIS COPYRIGHT: BIOL ABS. RRM RESEARCH ARTICLE RABBIT MERCURY CHLORIDE CADMIUM CHLORIDE POTASSIUM CHROMATE SODIUM ARSENITE NEPHROTOXICITY,ELEMENTAL ANALYSIS OF RENAL SLICES BY PROTON-INDUCED X-RAY EMISSION Abs: BIOSIS COPYRIGHT: BIOL ABS. RRM RESEARCH ARTICLE RABBIT MERCURY CHLORIDE CADMIUM CHLORIDE POTASSIUM CHROMATE SODIUM ARSENITE NEPHROTOXICITY
1237346,Centeno M et al. 1993,INFLUENCE OF PRODUCTION PROCESSING AND STORAGE CONDITIONS OF RESTING EGGS OF STREPTOCEPHALUS PROBOSCIDEUS CRUSTACEA BRANCHIOPODA ANOSTRACA ON THE SENSITIVITY OF LARVAE TO SELECTED REFERENCE TOXICANTS,BIOSIS COPYRIGHT: BIOL ABS. RRM RESEARCH ARTICLE STREPTOCEPHALUS-PROBOSCIDEUS DAPHNIA-MAGNA INVERTEBRATE AQUATIC TOXICITY WATER QUALITY,INFLUENCE OF PRODUCTION PROCESSING AND STORAGE CONDITIONS OF RESTING EGGS OF STREPTOCEPHALUS PROBOSCIDEUS CRUSTACEA BRANCHIOPODA ANOSTRACA ON THE SENSITIVITY OF LARVAE TO SELECTED REFERENCE TOXICANTS Abs: BIOSIS COPYRIGHT: BIOL ABS. RRM RESEARCH ARTICLE STREPTOCEPHALUS-PROBOSCIDEUS DAPHNIA-MAGNA INVERTEBRATE AQUATIC TOXICITY WATER QUALITY
1237345,Valdes-Hevia et al. 1993,SENSITIVE METHOD FOR DETERMINATION OF LEAD BY POTASSIUM DICHROMATE-LACTIC ACID HYDRIDE GENERATION INDUCTIVELY COUPLED PLASMA ATOMIC EMISSION SPECTROMETRY,BIOSIS COPYRIGHT: BIOL ABS. RRM RESEARCH ARTICLE HUMAN ATMOSPHERIC LEAD POLLUTANT FOOD SAMPLE PLUMBANE GENERATION ANALYTICAL METHOD,SENSITIVE METHOD FOR DETERMINATION OF LEAD BY POTASSIUM DICHROMATE-LACTIC ACID HYDRIDE GENERATION INDUCTIVELY COUPLED PLASMA ATOMIC EMISSION SPECTROMETRY Abs: BIOSIS COPYRIGHT: BIOL ABS. RRM RESEARCH ARTICLE HUMAN ATMOSPHERIC LEAD POLLUTANT FOOD SAMPLE PLUMBANE GENERATION ANALYTICAL METHOD
1237340,Kochhar and  Howard 1993,Effect of different oxidation states of chromium in causing chromosome alterations in cultured CHO cells,"Four chromium salts with different oxidation states were tested for their influence in causing chromosome aberrations and sister-chromatid exchange in Chinese hamster ovary cellsin vitro. Cell cultures were treated with CrO3, K2Cr2O7, CrCl2 and Cr(NO3)3.9H2O at concentrations of 10?7, 10?6, 10?5 and 10?4 M for the aberration assay, and 10?8, 10?7, 10?6 and 10?5 M for the sister-chromatid exchange assay. It was noticed that Cr (VI) compounds-CrO3 and K2Cr2O7-considerably enhanced the frequencies of aberrations and sister-chromatid exchanges compared to the control cultures. CrCl2 and Cr(NO3)3.9H2O?Cr (II) and Cr (III) respectively-caused a slight increase in sister-chromatid exchange rates, but the frequencies of aberrations were almost unchanged compared to the controls. These investigations indicate a definite link between the metals and changes produced in the mammalian chromosomes, reaffirming the evidence of carcinogenic potential of Cr (VI) observed by other investigators.","Effect of different oxidation states of chromium in causing chromosome alterations in cultured CHO cells Abs: Four chromium salts with different oxidation states were tested for their influence in causing chromosome aberrations and sister-chromatid exchange in Chinese hamster ovary cellsin vitro. Cell cultures were treated with CrO3, K2Cr2O7, CrCl2 and Cr(NO3)3.9H2O at concentrations of 10?7, 10?6, 10?5 and 10?4 M for the aberration assay, and 10?8, 10?7, 10?6 and 10?5 M for the sister-chromatid exchange assay. It was noticed that Cr (VI) compounds-CrO3 and K2Cr2O7-considerably enhanced the frequencies of aberrations and sister-chromatid exchanges compared to the control cultures. CrCl2 and Cr(NO3)3.9H2O?Cr (II) and Cr (III) respectively-caused a slight increase in sister-chromatid exchange rates, but the frequencies of aberrations were almost unchanged compared to the controls. These investigations indicate a definite link between the metals and changes produced in the mammalian chromosomes, reaffirming the evidence of carcinogenic potential of Cr (VI) observed by other investigators."
1237337,Bishnoi et al. 1993,"Effect of chromium on photosynthesis, respiration and nitrogen fixation in pea (Pisum sativum L.) seedlings","BIOSIS COPYRIGHT: BIOL ABS. Application of Cr6+, as K2Cr2O7, to pea seedlings severely depressed the overall capacity of plants to carry out photosynthesis, respiration and symbiotic nitrogen fixation. The deleterious effect became more pronounced with increasing concentrations of Cr6+ as well as with the duration of exposure. Treatment with the metal caused a reduction in chlorophyll content, photosynthetic activity per unit leaf area and in the activities of Photosystems I and II. In isolated chloroplasts, exogenously added Cr6+ had little effect on the activity of Photosystem Il whereas that of Photosystem I was markedly inhibited. At low concentrations, Cr6+ diminished the capacity of plants to fix atmospheric nitrogen largely by interfering with the formation of nodules, but at higher concentrations and with a prolonged period of the treatment, efficiency of the developed nodules to fix nitrogen was also impaired. During initial stages of treatment with Cr6+ the order of relative sensitivity","Effect of chromium on photosynthesis, respiration and nitrogen fixation in pea (Pisum sativum L.) seedlings Abs: BIOSIS COPYRIGHT: BIOL ABS. Application of Cr6+, as K2Cr2O7, to pea seedlings severely depressed the overall capacity of plants to carry out photosynthesis, respiration and symbiotic nitrogen fixation. The deleterious effect became more pronounced with increasing concentrations of Cr6+ as well as with the duration of exposure. Treatment with the metal caused a reduction in chlorophyll content, photosynthetic activity per unit leaf area and in the activities of Photosystems I and II. In isolated chloroplasts, exogenously added Cr6+ had little effect on the activity of Photosystem Il whereas that of Photosystem I was markedly inhibited. At low concentrations, Cr6+ diminished the capacity of plants to fix atmospheric nitrogen largely by interfering with the formation of nodules, but at higher concentrations and with a prolonged period of the treatment, efficiency of the developed nodules to fix nitrogen was also impaired. During initial stages of treatment with Cr6+ the order of relative sensitivity"
1237335,Van Beelen and  Fleuren-Kemila 1993,Toxic effects of pentachlorophenol and other pollutants on the mineralization of acetate in several soils,"BIOSIS COPYRIGHT: BIOL ABS. The mineralization of (14C)acetate was studied in bottles with fresh soil and groundwater. Addition of toxicants inhibited the formation of 14CO2 and dose-effect curves were obtained. The acetate mineralization was not inhibited by zinc, cadmium, K2Cr2O7, chloropyrifos, and paraquat in an acid sandy soil at 1000 mg/kg dry soil. The IC10 is the toxicant concentration which inhibits 10% of the initial mineralization rate. The IC10 concentrations for 3,4-dichloroaniline, triphenyltin, and ortho-xylene were 48, 96, and 730 mg/kg, respectively, in the acid sandy soil. The IC10 of pentachlorophenol was measured in samples from the acid sandy soil and in several other soil and subsoil samples. The geometrical mean of the 13 IC10 values was 16 mg pentachlorophenol/kg. A statistical method was used to calculate the PCP concentration above which 5% of the most sensitive acetate-mineralizing communities in all soils are influenced. The best estimate of this concentration is 0.3 m","Toxic effects of pentachlorophenol and other pollutants on the mineralization of acetate in several soils Abs: BIOSIS COPYRIGHT: BIOL ABS. The mineralization of (14C)acetate was studied in bottles with fresh soil and groundwater. Addition of toxicants inhibited the formation of 14CO2 and dose-effect curves were obtained. The acetate mineralization was not inhibited by zinc, cadmium, K2Cr2O7, chloropyrifos, and paraquat in an acid sandy soil at 1000 mg/kg dry soil. The IC10 is the toxicant concentration which inhibits 10% of the initial mineralization rate. The IC10 concentrations for 3,4-dichloroaniline, triphenyltin, and ortho-xylene were 48, 96, and 730 mg/kg, respectively, in the acid sandy soil. The IC10 of pentachlorophenol was measured in samples from the acid sandy soil and in several other soil and subsoil samples. The geometrical mean of the 13 IC10 values was 16 mg pentachlorophenol/kg. A statistical method was used to calculate the PCP concentration above which 5% of the most sensitive acetate-mineralizing communities in all soils are influenced. The best estimate of this concentration is 0.3 m"
1237334,Dave et al. 1993,Precision of the Nitocra spinipes acute toxicity test and the effect of salinity on toxicity of the reference toxicant potassium bichromate,"BIOSIS COPYRIGHT: BIOL ABS. The precision of the 96-h LC50 test with the eurohaline copepod Nitocra spinipes was evaluated from a data set containing 85 tests with the reference toxicant potassium bichromate conducted at 12 laboratories during a 12-year period. The overall mean was 30 mg as K2Cr2O7 with a coefficient of variation (CV) of 47% (N = 85). Since salinity differed between tests (7-33 ), it explained part of the variation (ca. 25%; Pearson two-tailed test r = 0.49; p = 0.0000; N = 85). The effect of salinity on Cr(VI) toxicity was confirmed in an experiment with 4 salinities (3.4, 6.8, 14.6, and 27 ) and was explained to 99% by the equation 96-h LC50 (mg/L) = 2.58 + 1.79ities ranged from 8 to 35% (repeatability). Interlaboratory CVs at two salinities were 42% (N = 11) at 7-9t 15-16 .","Precision of the Nitocra spinipes acute toxicity test and the effect of salinity on toxicity of the reference toxicant potassium bichromate Abs: BIOSIS COPYRIGHT: BIOL ABS. The precision of the 96-h LC50 test with the eurohaline copepod Nitocra spinipes was evaluated from a data set containing 85 tests with the reference toxicant potassium bichromate conducted at 12 laboratories during a 12-year period. The overall mean was 30 mg as K2Cr2O7 with a coefficient of variation (CV) of 47% (N = 85). Since salinity differed between tests (7-33 ), it explained part of the variation (ca. 25%; Pearson two-tailed test r = 0.49; p = 0.0000; N = 85). The effect of salinity on Cr(VI) toxicity was confirmed in an experiment with 4 salinities (3.4, 6.8, 14.6, and 27 ) and was explained to 99% by the equation 96-h LC50 (mg/L) = 2.58 + 1.79ities ranged from 8 to 35% (repeatability). Interlaboratory CVs at two salinities were 42% (N = 11) at 7-9t 15-16 ."
1237333,Rao and  Kaiwar 1993,"Reduction of potassium chromate by D-fructose, D-galactose, D-mannose, D-glucose, and L-sorbose","BIOSIS COPYRIGHT: BIOL ABS. Chromate is ready reduced by various saccharides under different experimental conditions, and its reduction has been followed using absorption and EPR spectroscopies and electrochemistry. The reduction of Cr(VI) was found to be characteristic of the saccharide used and the reductive capabilities follow a trend, D-fructose L-sorbose D-galactose D-mannose D-glucose at pH 1.65 and D-fructose D-galactose D-mannose L-sorbose D-glucose at pH 0.35. Similar trends were noticed from EPR and electrochemistry studies. As the reduction of chromate was found to go via soluble, reactive, and relatively long-lived Cr(V) intermediates having different life times, the biological toxicity and ecological hazard created in the presence of Cr(VI) salts by various molecules containing such saccharide moieties is expected to follow a reverse trend.","Reduction of potassium chromate by D-fructose, D-galactose, D-mannose, D-glucose, and L-sorbose Abs: BIOSIS COPYRIGHT: BIOL ABS. Chromate is ready reduced by various saccharides under different experimental conditions, and its reduction has been followed using absorption and EPR spectroscopies and electrochemistry. The reduction of Cr(VI) was found to be characteristic of the saccharide used and the reductive capabilities follow a trend, D-fructose L-sorbose D-galactose D-mannose D-glucose at pH 1.65 and D-fructose D-galactose D-mannose L-sorbose D-glucose at pH 0.35. Similar trends were noticed from EPR and electrochemistry studies. As the reduction of chromate was found to go via soluble, reactive, and relatively long-lived Cr(V) intermediates having different life times, the biological toxicity and ecological hazard created in the presence of Cr(VI) salts by various molecules containing such saccharide moieties is expected to follow a reverse trend."
1237329,Villalobos-Pietrini et al. 1993,Cytogenetic evaluation of the effects of chromium and detergents in Vicia faba,"BIOSIS COPYRIGHT: BIOL ABS. The clastogenic effect of two detergents one anionic (Roma) and another nonionic (Triton X-100), potassium dichromate, and various concentrations of the mixtures metal-detergents was analyzed in the meristematic cells of the root tips of Vicia faba. The chromium compound induced chromosomal aberrations as well as c-metaphases in similar frequencies as the mixture chromium- surfactants. The detergents did not produce cytogenetic disturbances, nor did they facilitate the clastogenic effects of chromium.","Cytogenetic evaluation of the effects of chromium and detergents in Vicia faba Abs: BIOSIS COPYRIGHT: BIOL ABS. The clastogenic effect of two detergents one anionic (Roma) and another nonionic (Triton X-100), potassium dichromate, and various concentrations of the mixtures metal-detergents was analyzed in the meristematic cells of the root tips of Vicia faba. The chromium compound induced chromosomal aberrations as well as c-metaphases in similar frequencies as the mixture chromium- surfactants. The detergents did not produce cytogenetic disturbances, nor did they facilitate the clastogenic effects of chromium."
1237328,Joshi and  Patil 1992,"Effect of water temperature, pH and hardness on the toxicity of chromium trioxide to female frog, Rana cyanophlyctis","BIOSIS COPYRIGHT: BIOL ABS. Influence of temperature (15.28 and 35? C), pH (4.7 and 10) and hardness (10,100 and 300 mg/l CaCO3) on the toxicity of chromium trioxide (VI) to R. cyanophlyctis was investigated using static renewal bioassay test. High temperature, low pH and hardness resulted in higher mortality rate while low temperature, high pH and hardness ameliorated the chromium toxicity.","Effect of water temperature, pH and hardness on the toxicity of chromium trioxide to female frog, Rana cyanophlyctis Abs: BIOSIS COPYRIGHT: BIOL ABS. Influence of temperature (15.28 and 35? C), pH (4.7 and 10) and hardness (10,100 and 300 mg/l CaCO3) on the toxicity of chromium trioxide (VI) to R. cyanophlyctis was investigated using static renewal bioassay test. High temperature, low pH and hardness resulted in higher mortality rate while low temperature, high pH and hardness ameliorated the chromium toxicity."
1237327,Aspinall et al. 1993,Chemical structure of the core region of Campylobacter jejuni serotype O:2 lipopolysaccharide,"BIOSIS COPYRIGHT: BIOL ABS. The complete structure for the core region of Campylobacter jejuni serotype O:2 lipopolysaccharide (LPS) was assigned through studies on derivatives of the liberated oligosaccharide (OS 2) and the intact LPS. Structure determinations were performed using 1H-NMR spectroscopy, methylation studies supported by fast-atom-bombardment mass spectrometry and linkage analysis by gas chromatography/mass spectrometry, Smith degradation, and oxidation with chromium trioxide.","Chemical structure of the core region of Campylobacter jejuni serotype O:2 lipopolysaccharide Abs: BIOSIS COPYRIGHT: BIOL ABS. The complete structure for the core region of Campylobacter jejuni serotype O:2 lipopolysaccharide (LPS) was assigned through studies on derivatives of the liberated oligosaccharide (OS 2) and the intact LPS. Structure determinations were performed using 1H-NMR spectroscopy, methylation studies supported by fast-atom-bombardment mass spectrometry and linkage analysis by gas chromatography/mass spectrometry, Smith degradation, and oxidation with chromium trioxide."
1237325,Shimon 1993,A NOVEL BIOLUMINESCENT TEST FOR CHRONIC AND ACUTE TOXICANTS IN WATER,BIOSIS COPYRIGHT: BIOL ABS. RRM ABSTRACT POTASSIUM CHROMATE 3 5 DICHLOROPHENOL LEAD CHLORIDE POTASSIUM CYANIDE CADMIUM CHLORIDE DIELDRIN FLUORENTAN PENTACHLOROBENZENE NICKEL SULFATE SODIUM AZIDE ANALYTICAL METHOD,A NOVEL BIOLUMINESCENT TEST FOR CHRONIC AND ACUTE TOXICANTS IN WATER Abs: BIOSIS COPYRIGHT: BIOL ABS. RRM ABSTRACT POTASSIUM CHROMATE 3 5 DICHLOROPHENOL LEAD CHLORIDE POTASSIUM CYANIDE CADMIUM CHLORIDE DIELDRIN FLUORENTAN PENTACHLOROBENZENE NICKEL SULFATE SODIUM AZIDE ANALYTICAL METHOD
1237320,Ikarashi et al. 1992,DIFFERENCES OF DRAINING LYMPH NODE CELL PROLIFERATION AMONG MICE RATS AND GUINEA-PIGS FOLLOWING EXPOSURE TO METAL ALLERGENS,BIOSIS COPYRIGHT: BIOL ABS. RRM ABSTRACT CONTACT SENSITIVITY NICKEL SULFATE POTASSIUM DICHROMATE COBALT CHLORIDE,DIFFERENCES OF DRAINING LYMPH NODE CELL PROLIFERATION AMONG MICE RATS AND GUINEA-PIGS FOLLOWING EXPOSURE TO METAL ALLERGENS Abs: BIOSIS COPYRIGHT: BIOL ABS. RRM ABSTRACT CONTACT SENSITIVITY NICKEL SULFATE POTASSIUM DICHROMATE COBALT CHLORIDE
1237318,Liu et al. 1993,ALLERGENS CAUSING SHOE DERMATITIS,BIOSIS COPYRIGHT: BIOL ABS. RRM ABSTRACT HUMAN MERCAPTOBENZOTHIAZOLE THIURAM POTASSIUM DICHROMATE,ALLERGENS CAUSING SHOE DERMATITIS Abs: BIOSIS COPYRIGHT: BIOL ABS. RRM ABSTRACT HUMAN MERCAPTOBENZOTHIAZOLE THIURAM POTASSIUM DICHROMATE
1237314,Goldschmidt 1993,An analytical approach for reducing workplace health hazards through substitution,"BIOSIS COPYRIGHT: BIOL ABS. Substitutions for a harmful chemical implies that the desired function is maintained without using the harmful chemical in question. Improvement can be achieved if a less harmful chemical can be used or the same function obtained by changing the process and eliminating the harmful chemical agent. In 1982, Denmark introduced an authority regulation requiring substitution if functional and economical alternatives exist. This paper summarizes the results of 162 examples of substitution investigated by the Danish Occupational Health Services. The identification and implementation of substitution alternatives is described as an iterative process with seven distinct steps. Several tools that are useful in evaluating alternatives are described, including Hansen solubility parameters and vapor hazard ratios. In addition to the technical issues surrounding substitution, this paper describes the social interactions necessary to include all affected individuals, along with those","An analytical approach for reducing workplace health hazards through substitution Abs: BIOSIS COPYRIGHT: BIOL ABS. Substitutions for a harmful chemical implies that the desired function is maintained without using the harmful chemical in question. Improvement can be achieved if a less harmful chemical can be used or the same function obtained by changing the process and eliminating the harmful chemical agent. In 1982, Denmark introduced an authority regulation requiring substitution if functional and economical alternatives exist. This paper summarizes the results of 162 examples of substitution investigated by the Danish Occupational Health Services. The identification and implementation of substitution alternatives is described as an iterative process with seven distinct steps. Several tools that are useful in evaluating alternatives are described, including Hansen solubility parameters and vapor hazard ratios. In addition to the technical issues surrounding substitution, this paper describes the social interactions necessary to include all affected individuals, along with those"
1237312,Mccann 1992,Occupational and environmental hazards in art,"BIOSIS COPYRIGHT: BIOL ABS. Artists and craftspeople, art teachers, hobbyists, and children often use art materials containing toxic chemicals without suitable precautions and often without the knowledge that their art materials are hazardous. The Center for Safety in the Arts, a national clearinghouse for research and education on hazards in the visual and performing arts, answers telephoned and written inquiries on art hazards, distributes publications, publishes a newsletter, and offers educational programs and consultative services to arts organizations.","Occupational and environmental hazards in art Abs: BIOSIS COPYRIGHT: BIOL ABS. Artists and craftspeople, art teachers, hobbyists, and children often use art materials containing toxic chemicals without suitable precautions and often without the knowledge that their art materials are hazardous. The Center for Safety in the Arts, a national clearinghouse for research and education on hazards in the visual and performing arts, answers telephoned and written inquiries on art hazards, distributes publications, publishes a newsletter, and offers educational programs and consultative services to arts organizations."
1237311,Kusk and  Nyholm 1992,Toxic effects of chlorinated organic compounds and potassium dichromate on growth rate and photosynthesis of marine phytoplankton,"BIOSIS COPYRIGHT: BIOL ABS. The toxic effects of potassium dichromate (K2Cr2O7),3,4-dichloroaniline (DCA) and 2,4-dichlorophenol (DCP) on the photosynthesis of natural marine phytoplankton and five species of marine microalgae were investigated. Effect concentrations corresponding to a 50% depression of photosynthesis (6h EC50) were found within relatively narrow ranges of 3.3-7.2 mg/l and 1.5-12 mg/l for DCA and DCP respectively, whereas the sensitivities towards K2Cr2O7 varied much more. The effects of DCA and DCP on the growth rate of some species were also investigated. EC50 values for DCP and DCA were found within the ranges 0.5-20 mg/l and 1.1-2.6 mg/l respectively. Diatoms were generally found to be the most sensitive species.","Toxic effects of chlorinated organic compounds and potassium dichromate on growth rate and photosynthesis of marine phytoplankton Abs: BIOSIS COPYRIGHT: BIOL ABS. The toxic effects of potassium dichromate (K2Cr2O7),3,4-dichloroaniline (DCA) and 2,4-dichlorophenol (DCP) on the photosynthesis of natural marine phytoplankton and five species of marine microalgae were investigated. Effect concentrations corresponding to a 50% depression of photosynthesis (6h EC50) were found within relatively narrow ranges of 3.3-7.2 mg/l and 1.5-12 mg/l for DCA and DCP respectively, whereas the sensitivities towards K2Cr2O7 varied much more. The effects of DCA and DCP on the growth rate of some species were also investigated. EC50 values for DCP and DCA were found within the ranges 0.5-20 mg/l and 1.1-2.6 mg/l respectively. Diatoms were generally found to be the most sensitive species."
1237308,Brandao et al. 1992,Correlation between the in vitro cytotoxicity to cultured fathead minnow fish cells and fish lethality data for 50 chemicals,"BIOSIS COPYRIGHT: BIOL ABS. Neutral red uptake inhibition was investigated as an alternative method for the assessment of ecotoxicity. The 50 chemicals tested include different kinds of inorganic compounds and organic compounds such as alcohols, acids, ketones, esters, and others. The xenobiotics were applied at different concentrations to cultured FHM (fathead minnow fish) cells. After 2 hours contact time neutral red uptake inhibition was measured. The results are expressed as the NI50 value, which is the concentration of test compound required to induce a 50% reduction in neutral red uptake. The NI50 values were compared with fish lethality data (LC50) obtained in golden orfe by Juhnke and Ludemann (1978). A false positive cytotoxic result was observed for 1,4-dioxane. For the remainder 49 chemicals a correlation coefficient r=0.89 was found. Hence it appears that the neutral red uptake inhibition in cultured fish cells can be considered as a valuable tool for in vitro ecotoxicity testing of a","Correlation between the in vitro cytotoxicity to cultured fathead minnow fish cells and fish lethality data for 50 chemicals Abs: BIOSIS COPYRIGHT: BIOL ABS. Neutral red uptake inhibition was investigated as an alternative method for the assessment of ecotoxicity. The 50 chemicals tested include different kinds of inorganic compounds and organic compounds such as alcohols, acids, ketones, esters, and others. The xenobiotics were applied at different concentrations to cultured FHM (fathead minnow fish) cells. After 2 hours contact time neutral red uptake inhibition was measured. The results are expressed as the NI50 value, which is the concentration of test compound required to induce a 50% reduction in neutral red uptake. The NI50 values were compared with fish lethality data (LC50) obtained in golden orfe by Juhnke and Ludemann (1978). A false positive cytotoxic result was observed for 1,4-dioxane. For the remainder 49 chemicals a correlation coefficient r=0.89 was found. Hence it appears that the neutral red uptake inhibition in cultured fish cells can be considered as a valuable tool for in vitro ecotoxicity testing of a"
1237307,Xu et al. 1992,Determination of aluminium in human brain tissue by electrothermal atomic absorption spectrometry,"BIOSIS COPYRIGHT: BIOL ABS. Brain tissue is rich in phosphorus and alkali and alkaline earth metals. A synergistic interference has been observed with the determination of aluminium by electrothermal atomic absorption spectrometry when phosphorus is present in the sample alone with alkali or alkaline earth metals. For the determination of aluminium in human brain samples, potassium dichromate was found to be an effective chemical modifier. The concentration of aluminium in Nation Institute of Standards and Technology (NIST) Standard Reference Materials (SRMs) Citrus Leaves (SRM 1572), Oyster Tissue (SRM 1566a) and in National Institute for Environmental Studies (NIES) Certified Reference Material (CRM) No. 6 mussel were determined. Values of 76.6 | 4.2, 86.8 | 0.5 and 55.5 | 10.1 mug g-1 were obtained before the use of the modifier, and 88.2 | 6.2, 197.7 | 6.8 and 215.0 | 12.5 mug g-1 after the use of potassium dichromate as chemical modifier for Citrus Leaves, Oyster Tissue and Mussel, respectivel","Determination of aluminium in human brain tissue by electrothermal atomic absorption spectrometry Abs: BIOSIS COPYRIGHT: BIOL ABS. Brain tissue is rich in phosphorus and alkali and alkaline earth metals. A synergistic interference has been observed with the determination of aluminium by electrothermal atomic absorption spectrometry when phosphorus is present in the sample alone with alkali or alkaline earth metals. For the determination of aluminium in human brain samples, potassium dichromate was found to be an effective chemical modifier. The concentration of aluminium in Nation Institute of Standards and Technology (NIST) Standard Reference Materials (SRMs) Citrus Leaves (SRM 1572), Oyster Tissue (SRM 1566a) and in National Institute for Environmental Studies (NIES) Certified Reference Material (CRM) No. 6 mussel were determined. Values of 76.6 | 4.2, 86.8 | 0.5 and 55.5 | 10.1 mug g-1 were obtained before the use of the modifier, and 88.2 | 6.2, 197.7 | 6.8 and 215.0 | 12.5 mug g-1 after the use of potassium dichromate as chemical modifier for Citrus Leaves, Oyster Tissue and Mussel, respectivel"
1237299,Liu et al. 1992,Effects of trivalent and hexavalent chromium on root growth an cell division of Allium cepa,"BIOSIS COPYRIGHT: BIOL ABS. The effects of trivalent and hexavalent chromium on root growth, cell division and chromosome morphology of Allium cepa were studied. The concentrations used of chromium nitrate and potassium dichromate were 210-2, 2he results showed that both trivalent and hexavalent chromium inhibit root growth and cause mitotic irregularities comprising c-mitosis, anaphase bridges, chromosome stickiness, and chromosome fragmentation and lagging. When compared with chromium nitrate on the equimolar basis, potassium dichromate showed a stronger inhibitory and toxic effect on root growth and cell division, respectively. The possible mechanism of the Cr poisoning of root meristem cells of Allium cepa is also briefly discussed.","Effects of trivalent and hexavalent chromium on root growth an cell division of Allium cepa Abs: BIOSIS COPYRIGHT: BIOL ABS. The effects of trivalent and hexavalent chromium on root growth, cell division and chromosome morphology of Allium cepa were studied. The concentrations used of chromium nitrate and potassium dichromate were 210-2, 2he results showed that both trivalent and hexavalent chromium inhibit root growth and cause mitotic irregularities comprising c-mitosis, anaphase bridges, chromosome stickiness, and chromosome fragmentation and lagging. When compared with chromium nitrate on the equimolar basis, potassium dichromate showed a stronger inhibitory and toxic effect on root growth and cell division, respectively. The possible mechanism of the Cr poisoning of root meristem cells of Allium cepa is also briefly discussed."
1237294,Cowgill et al. 1991,The sensitivity of Lemna gibba G-3 and four clones of Lemna minor to eight common chemicals using a 7-day test,"BIOSIS COPYRIGHT: BIOL ABS. The objective of this study was to estimate the EC50 (50% reduction in the number of plants or fronds as compared to controls) and their no observable effect level (NOEL) of eight common chemicals to Lemna gibba G-3 and four clones of L. minor over a 7-day period. Endpoints examined were the number of plants, the number of fronds, and the dry weight. The response of Lemna to these chemicals in decreasing order of sensitivity was K2Cr2O7 = 4-chlorophenol phenol chlorobenzene chloroform diethanolamine ethanol acetone. Data on the sensitivities of other aquatic organisms to these chemicals are also included. Significant correlation coefficients were found between the toxicity of hexavalent Cr and the sulfate and hardness of the growth/test media for a green alga, two cladocerans, and five clones of Lemna. The toxicity of hexavalent Cr increased as the sulfate concentration and hardness decreased. The inclusion of data from a marine diatom and a","The sensitivity of Lemna gibba G-3 and four clones of Lemna minor to eight common chemicals using a 7-day test Abs: BIOSIS COPYRIGHT: BIOL ABS. The objective of this study was to estimate the EC50 (50% reduction in the number of plants or fronds as compared to controls) and their no observable effect level (NOEL) of eight common chemicals to Lemna gibba G-3 and four clones of L. minor over a 7-day period. Endpoints examined were the number of plants, the number of fronds, and the dry weight. The response of Lemna to these chemicals in decreasing order of sensitivity was K2Cr2O7 = 4-chlorophenol phenol chlorobenzene chloroform diethanolamine ethanol acetone. Data on the sensitivities of other aquatic organisms to these chemicals are also included. Significant correlation coefficients were found between the toxicity of hexavalent Cr and the sulfate and hardness of the growth/test media for a green alga, two cladocerans, and five clones of Lemna. The toxicity of hexavalent Cr increased as the sulfate concentration and hardness decreased. The inclusion of data from a marine diatom and a"
1237288,Goodman 1992,LEAD CHROMATE EXPOSURES AND ELEVATED BLOOD LEAD LEVELS IN WORKERS IN THE PLASTICS PIGMENTING INDUSTRY TEXAS 1990,BIOSIS COPYRIGHT: BIOL ABS. RRM HUMAN BLOOD OSHA USA,LEAD CHROMATE EXPOSURES AND ELEVATED BLOOD LEAD LEVELS IN WORKERS IN THE PLASTICS PIGMENTING INDUSTRY TEXAS 1990 Abs: BIOSIS COPYRIGHT: BIOL ABS. RRM HUMAN BLOOD OSHA USA
1237284,El-Wear et al. 1992,Sorption of technetium on inorganic sorbents and natural minerals,"BIOSIS COPYRIGHT: BIOL ABS. The sorption behavior of the pertechnetate anion in various solid-solution systems under aerobic conditions and pH 1.3-12.5 has been investigated. Batch techniques were employed. On most of natural minerals only surface adsorption occurs. Rs-values were no larger than 2.0 mlsorption on various natural minerals and rocks such as sandstone, basalt, granite, pyrite, peat and others are compared with the analogous processes on artificial inorganic sorbents: titanium oxides (thermoxide-34, thermoxide-3), crystalline cadmium sulfide, zirconium phosphate, and complex inorganic sorbents: antimony oxide - silicon oxide - phosphorus pentoxide, antimony oxide - silicone oxide - aluminum oxide, lithium oxide - manganese oxide - aluminium oxide - water, lithium oxide - titanium oxide - chromium oxide - water. For comparison the sorption of Tc on some organic sorbents was included. The solubility of Tc2 S7 in water was measured to be 0.257 g/l. It has been shown that preliminary irra","Sorption of technetium on inorganic sorbents and natural minerals Abs: BIOSIS COPYRIGHT: BIOL ABS. The sorption behavior of the pertechnetate anion in various solid-solution systems under aerobic conditions and pH 1.3-12.5 has been investigated. Batch techniques were employed. On most of natural minerals only surface adsorption occurs. Rs-values were no larger than 2.0 mlsorption on various natural minerals and rocks such as sandstone, basalt, granite, pyrite, peat and others are compared with the analogous processes on artificial inorganic sorbents: titanium oxides (thermoxide-34, thermoxide-3), crystalline cadmium sulfide, zirconium phosphate, and complex inorganic sorbents: antimony oxide - silicon oxide - phosphorus pentoxide, antimony oxide - silicone oxide - aluminum oxide, lithium oxide - manganese oxide - aluminium oxide - water, lithium oxide - titanium oxide - chromium oxide - water. For comparison the sorption of Tc on some organic sorbents was included. The solubility of Tc2 S7 in water was measured to be 0.257 g/l. It has been shown that preliminary irra"
1237283,Gilbert et al. 1992,Rapid assessment of metabolic activity in marine microalgae: Application in ecotoxicological tests and evaluation of water quality,"BIOSIS COPYRIGHT: BIOL ABS. A new method for the assessment of the effects of several contaminants on marine microalgae, Tetraselmis suecica (Kyling) Butcher, Skeletonema costatum (Grev.) Cleve, and Prorocentrum lima (Ehrenberg) Dode was developed in 1990. The method is based on the measurement of cell esterase activity using a fluorimetric stain, fluorescein diacetate (FDA), selected from amongst three strains (FDA, Neutral Red, thiazolyl tetrazolium bromure) for its higher sensitivity. Biochemical (Km, Vmax) and physiological (growth, specific activity) aspects of the enzymatic activity as revealed by the FDA method are discussed. Different categories of compounds (weed-killers, insecticides, metals) and some water samples from Seine Bay were tested for their toxic effects on microalgae. Experiment were performed on microplates using a fluorimetric microplate reader. The various steps of the experiments and data-processing were controlled by software. Applications of the system to rapid ecotoxic","Rapid assessment of metabolic activity in marine microalgae: Application in ecotoxicological tests and evaluation of water quality Abs: BIOSIS COPYRIGHT: BIOL ABS. A new method for the assessment of the effects of several contaminants on marine microalgae, Tetraselmis suecica (Kyling) Butcher, Skeletonema costatum (Grev.) Cleve, and Prorocentrum lima (Ehrenberg) Dode was developed in 1990. The method is based on the measurement of cell esterase activity using a fluorimetric stain, fluorescein diacetate (FDA), selected from amongst three strains (FDA, Neutral Red, thiazolyl tetrazolium bromure) for its higher sensitivity. Biochemical (Km, Vmax) and physiological (growth, specific activity) aspects of the enzymatic activity as revealed by the FDA method are discussed. Different categories of compounds (weed-killers, insecticides, metals) and some water samples from Seine Bay were tested for their toxic effects on microalgae. Experiment were performed on microplates using a fluorimetric microplate reader. The various steps of the experiments and data-processing were controlled by software. Applications of the system to rapid ecotoxic"
1237280,Lucas 1992,Health hazards associated with the cyanotype printing process,"The health hazards involved in making handmade quilts involving a cyanotype printing process were evaluated. An artist engaged in creation of handmade quilts in her residence had experienced facial and finger edema, mucous membrane irritation, headaches, and nausea, was investigated. The cyanotype process was used to transfer photographic prints to fabric, which was later incorporated in quilts. Chemicals used in the cyanotype process included potassium-dichromate (7778509), which is known to be highly toxic and a skin sensitizer. Even though the artist had discontinued use of the process, symptoms recurred when she handled or sewed cloth treated with the cyanotype process. Work surfaces tested positive for contamination with hexavalent chromium (CrVI). Air and vacuum sampling indicated that CrVI was not present at detectable levels. The author recommended discontinuing the use of the cyanotype process, or discontinue use of potassium-dichromate as fixative, decontaminating the basement with soap and water, washing fabrics thoroughly in hot water, and avoiding contact with other sources of chromates.","Health hazards associated with the cyanotype printing process Abs: The health hazards involved in making handmade quilts involving a cyanotype printing process were evaluated. An artist engaged in creation of handmade quilts in her residence had experienced facial and finger edema, mucous membrane irritation, headaches, and nausea, was investigated. The cyanotype process was used to transfer photographic prints to fabric, which was later incorporated in quilts. Chemicals used in the cyanotype process included potassium-dichromate (7778509), which is known to be highly toxic and a skin sensitizer. Even though the artist had discontinued use of the process, symptoms recurred when she handled or sewed cloth treated with the cyanotype process. Work surfaces tested positive for contamination with hexavalent chromium (CrVI). Air and vacuum sampling indicated that CrVI was not present at detectable levels. The author recommended discontinuing the use of the cyanotype process, or discontinue use of potassium-dichromate as fixative, decontaminating the basement with soap and water, washing fabrics thoroughly in hot water, and avoiding contact with other sources of chromates."
1237279,Sandhu et al. 1991,IDENTIFICATION OF ANEUPLOIDY-INDUCING AGENTS USING THE WHEAT SEEDLING ASSAY,BIOSIS COPYRIGHT: BIOL ABS. RRM TRITICUM-AESTIVUM VIRESCENT LEAVES WHITE SECTORS GREEN SECTORS CHROMIUM DICHROMATE CHROMIUM TRIOXIDE CYCLOPHOSPHAMIDE CLASTOGENICITY GENOTOXICITY,IDENTIFICATION OF ANEUPLOIDY-INDUCING AGENTS USING THE WHEAT SEEDLING ASSAY Abs: BIOSIS COPYRIGHT: BIOL ABS. RRM TRITICUM-AESTIVUM VIRESCENT LEAVES WHITE SECTORS GREEN SECTORS CHROMIUM DICHROMATE CHROMIUM TRIOXIDE CYCLOPHOSPHAMIDE CLASTOGENICITY GENOTOXICITY
1237278,Windeatt et al. 1991,THE USE OF SOIL-BASED PLANT TESTS BASED ON THE OECD GUIDELINES,BIOSIS COPYRIGHT: BIOL ABS. RRM ORGANIZATION FOR ECONOMIC COOPERATION AND DEVELOPMENT ORGANIC CHEMICALS INORGANIC CHEMICALS EMERGENCE EARLY PLANT GROWTH ECOTOXICOLOGY,THE USE OF SOIL-BASED PLANT TESTS BASED ON THE OECD GUIDELINES Abs: BIOSIS COPYRIGHT: BIOL ABS. RRM ORGANIZATION FOR ECONOMIC COOPERATION AND DEVELOPMENT ORGANIC CHEMICALS INORGANIC CHEMICALS EMERGENCE EARLY PLANT GROWTH ECOTOXICOLOGY
1237276,Midtgard and  Jelnes 1991,"Toxicology and occupational hazards of new materials and processes in metal surface treatment, powder metallurgy, technical ceramics, and fiber-reinforced plastics","BIOSIS COPYRIGHT: BIOL ABS. Many new materials and processes are about to find their way from the research laboratory into industry. The present paper describes some of these processes and provides an overview of possible occupational hazards and a list of chemicals used or produced in the processes. The technological areas that are considered are metal surface treatment (ion implantation, physical and chemical vapor deposition, plasma spraying), powder metallurgy, advanced technical ceramics, and fiber-reinforced plastics.","Toxicology and occupational hazards of new materials and processes in metal surface treatment, powder metallurgy, technical ceramics, and fiber-reinforced plastics Abs: BIOSIS COPYRIGHT: BIOL ABS. Many new materials and processes are about to find their way from the research laboratory into industry. The present paper describes some of these processes and provides an overview of possible occupational hazards and a list of chemicals used or produced in the processes. The technological areas that are considered are metal surface treatment (ion implantation, physical and chemical vapor deposition, plasma spraying), powder metallurgy, advanced technical ceramics, and fiber-reinforced plastics."
1237275,Hanawa et al. 1992,"Cytotoxicities of oxides, phosphates and sulphides of metals","BIOSIS COPYRIGHT: BIOL ABS. The cytotoxicities of oxides, phosphates and sulphides, which possibly form on dental alloys, were tested using the 'agar method"". The relative magnitudes of the cytotoxicities of these compounds exhibited tendencies similar to those of the metal components in the compounds. In correlation with dental amalgams, zinc oxide was the most cytotoxic, just as with metallic zinc, while tin oxides and mercury oxides exhibited no cytotoxicity. Zinc was the most influential element in the cytotoxicity of dental amalgams. On the other hand, in correlation with Ni-Cr alloys, Co-Cr alloys, and/or stainless steels a chromium oxide and a cobalt oxide showed serious cytotoxicity whereas the iron oxides were non-cytotoxic. Sulphides, which possibly form on silver alloys, showed cytotoxicity. Oxides and phosphates of titanium and aluminium, and hydroxyapatite, were not cytotoxic, supporting the use of these materials for implants. Not only the valence of an element but also the chemical","Cytotoxicities of oxides, phosphates and sulphides of metals Abs: BIOSIS COPYRIGHT: BIOL ABS. The cytotoxicities of oxides, phosphates and sulphides, which possibly form on dental alloys, were tested using the 'agar method"". The relative magnitudes of the cytotoxicities of these compounds exhibited tendencies similar to those of the metal components in the compounds. In correlation with dental amalgams, zinc oxide was the most cytotoxic, just as with metallic zinc, while tin oxides and mercury oxides exhibited no cytotoxicity. Zinc was the most influential element in the cytotoxicity of dental amalgams. On the other hand, in correlation with Ni-Cr alloys, Co-Cr alloys, and/or stainless steels a chromium oxide and a cobalt oxide showed serious cytotoxicity whereas the iron oxides were non-cytotoxic. Sulphides, which possibly form on silver alloys, showed cytotoxicity. Oxides and phosphates of titanium and aluminium, and hydroxyapatite, were not cytotoxic, supporting the use of these materials for implants. Not only the valence of an element but also the chemical"
1237269,Coleman and  Paran 1991,Biofilm concentration of chromium,BIOSIS COPYRIGHT: BIOL ABS. Removal of chromium from synthetic waste streams was studied using biofilms that developed on disks of a laboratory scale Rotating Biodisk Contactor (RBC). During its development the biofilm was continuously exposed to various concentrations of potassium dichromate. Chromium removal efficiency was about 98% during steady state addition of chromium (VI) at concentrations of 100 or 200 mg 1-1. Analysis of the major soluble chromium ions demonstrated that chronium (VI) was first reduced to chromium (III) which then appeared to be adsorbed by the biofilm. Chromium levels associated with the biofilm were found (by chemical analysis) to be 6.5-7.0% of its dried weight.,Biofilm concentration of chromium Abs: BIOSIS COPYRIGHT: BIOL ABS. Removal of chromium from synthetic waste streams was studied using biofilms that developed on disks of a laboratory scale Rotating Biodisk Contactor (RBC). During its development the biofilm was continuously exposed to various concentrations of potassium dichromate. Chromium removal efficiency was about 98% during steady state addition of chromium (VI) at concentrations of 100 or 200 mg 1-1. Analysis of the major soluble chromium ions demonstrated that chronium (VI) was first reduced to chromium (III) which then appeared to be adsorbed by the biofilm. Chromium levels associated with the biofilm were found (by chemical analysis) to be 6.5-7.0% of its dried weight.
1237267,Manzini et al. 1991,CONTACT SENSITIZATION TO NEWLY PATCH TESTED NON-DISPERSE TEXTILE DYES,BIOSIS COPYRIGHT: BIOL ABS. RRM HUMAN OCCUPATIONAL TOXICOLOGY OCCUPATIONAL HEALTH AND SAFETY TEXTILE INDUSTRY SUPRAMINE RED NEUTRICHROME RED SUPRAMINE YELLOW BRILLIANT GREEN TURQUOISE REACTIVE DIAZOL ORANGE,CONTACT SENSITIZATION TO NEWLY PATCH TESTED NON-DISPERSE TEXTILE DYES Abs: BIOSIS COPYRIGHT: BIOL ABS. RRM HUMAN OCCUPATIONAL TOXICOLOGY OCCUPATIONAL HEALTH AND SAFETY TEXTILE INDUSTRY SUPRAMINE RED NEUTRICHROME RED SUPRAMINE YELLOW BRILLIANT GREEN TURQUOISE REACTIVE DIAZOL ORANGE
1237264,Gaur and  Bhattacherjee 1991,Toxicity of selected chromium compounds in microbial bioassay system,"BIOSIS COPYRIGHT: BIOL ABS. The short term acute toxicity of potassium chromate, potassium dichromate and chromium sulphate had been compared in a simple microbial bioassay. The test parameters were, decrease in viability, genotoxicity and metal uptake. The LC50 values of Cr(III), dichromate Cr(VI) and chromate Cr(VI) for Escerichia coli were 16, 10 and 1.2 mug mL-1, respectively. Among the test substances potassium chromate was most toxic and showed no bioaccumulation while potassium dichromate was less toxic but resulted in significant bioaccumulation. Chromium sulphate was least toxic. As evident from loss of plasmid, genotoxicity was exhibited only by Cr (VI).","Toxicity of selected chromium compounds in microbial bioassay system Abs: BIOSIS COPYRIGHT: BIOL ABS. The short term acute toxicity of potassium chromate, potassium dichromate and chromium sulphate had been compared in a simple microbial bioassay. The test parameters were, decrease in viability, genotoxicity and metal uptake. The LC50 values of Cr(III), dichromate Cr(VI) and chromate Cr(VI) for Escerichia coli were 16, 10 and 1.2 mug mL-1, respectively. Among the test substances potassium chromate was most toxic and showed no bioaccumulation while potassium dichromate was less toxic but resulted in significant bioaccumulation. Chromium sulphate was least toxic. As evident from loss of plasmid, genotoxicity was exhibited only by Cr (VI)."
1237260,Rempel et al. 1991,Respiratory effects of exposure of shipyard workers to epoxy paints,"BIOSIS COPYRIGHT: BIOL ABS. Epoxy resin systems have been associated with occupational asthma in several case reports, but medical publications contain little on the potential adverse respiratory effects of these chemicals in exposed worker populations. To further evaluate the association of workplace exposure to epoxy paints and respiratory dysfunction, the cross workshift changes in pulmonary function and symptoms of 32 shipyard painters exposed to epoxy paints were compared with 28 shipyard painters not exposed to epoxy paints. The prevalence of lower respiratory tract symptoms was significantly higher among painters exposed to epoxy paints compared with controls. Among exposed painters the mean cross workshift change in forced expiratory volume in one second (FEV1) (-3.4%) was greater than the decrement in the non-exposed group (-1.4%). A significant linear relation was seen between % decrement in FEV1 and hours of exposure to epoxy paints. This study suggests that epoxy resin coatings as used","Respiratory effects of exposure of shipyard workers to epoxy paints Abs: BIOSIS COPYRIGHT: BIOL ABS. Epoxy resin systems have been associated with occupational asthma in several case reports, but medical publications contain little on the potential adverse respiratory effects of these chemicals in exposed worker populations. To further evaluate the association of workplace exposure to epoxy paints and respiratory dysfunction, the cross workshift changes in pulmonary function and symptoms of 32 shipyard painters exposed to epoxy paints were compared with 28 shipyard painters not exposed to epoxy paints. The prevalence of lower respiratory tract symptoms was significantly higher among painters exposed to epoxy paints compared with controls. Among exposed painters the mean cross workshift change in forced expiratory volume in one second (FEV1) (-3.4%) was greater than the decrement in the non-exposed group (-1.4%). A significant linear relation was seen between % decrement in FEV1 and hours of exposure to epoxy paints. This study suggests that epoxy resin coatings as used"
1237252,Centeno et al. 1990,THE DEVELOPMENT OF A SHORT-TERM STANDARD TOXICITY TEST WITH THE FAIRY SHRIMP STREPTOCEPHALUS-PROBOSCIDEUS CRUSTACEA ANOSTRACA,BIOSIS COPYRIGHT: BIOL ABS. RRM ABSTRACT LARVA NAUPLII INSTAR CYST MORTALITY SENSITIVITY SODIUM LAURYL SULFATE ZINC SULFATE TRICHLOROACETIC ACID POTASSIUM DICHROMATE CADMIUM CHLORIDE SODIUM PCP MERCURIC CHLORIDE COPPER SULFATE LC-50 FRESHWATER,THE DEVELOPMENT OF A SHORT-TERM STANDARD TOXICITY TEST WITH THE FAIRY SHRIMP STREPTOCEPHALUS-PROBOSCIDEUS CRUSTACEA ANOSTRACA Abs: BIOSIS COPYRIGHT: BIOL ABS. RRM ABSTRACT LARVA NAUPLII INSTAR CYST MORTALITY SENSITIVITY SODIUM LAURYL SULFATE ZINC SULFATE TRICHLOROACETIC ACID POTASSIUM DICHROMATE CADMIUM CHLORIDE SODIUM PCP MERCURIC CHLORIDE COPPER SULFATE LC-50 FRESHWATER
1237250,Reif 1990,The origin of magnetic spheroidal microparticles in soils of the Krusne hory Mts. (Czechoslovakia),"BIOSIS COPYRIGHT: BIOL ABS. Some magnetic spheroidal microparticles were determined in humus soil horizon ""A"" on the locality Jezeri in the Krusne hort Mts. Their morphology, physical and chemical properties were compared with those of spheroids isolated from a power plant fly ash. The results give evidence of a negative influence of solid industrial imissions on the soil quality.","The origin of magnetic spheroidal microparticles in soils of the Krusne hory Mts. (Czechoslovakia) Abs: BIOSIS COPYRIGHT: BIOL ABS. Some magnetic spheroidal microparticles were determined in humus soil horizon ""A"" on the locality Jezeri in the Krusne hort Mts. Their morphology, physical and chemical properties were compared with those of spheroids isolated from a power plant fly ash. The results give evidence of a negative influence of solid industrial imissions on the soil quality."
1237248,Diociaiuti and  Paoletti 1991,Structural characterization of air-oxidized chromium particles by extended energy-loss fine-structure spectroscopy,"BIOSIS COPYRIGHT: BIOL ABS. Extended energy-loss fine-structure spectroscopy (EXELFS) and electron energy-loss spectroscopy (EELS) microanalysis have been used to study the structural and chemcial modifications caused by interaction with the atmosphere of small, very reactive chromium (Cr) particles whose diameters range from 150 to 1300 . Analysis of the data allows us to deduce that the particles consist of a Cr core with a body-centred cubic structure and with a lattice parameter reduced by about 4% with respect to the bulk value by surface stresses (for the smallest diameter), surrounded by a Cr2O3 shell of about 15- width.","Structural characterization of air-oxidized chromium particles by extended energy-loss fine-structure spectroscopy Abs: BIOSIS COPYRIGHT: BIOL ABS. Extended energy-loss fine-structure spectroscopy (EXELFS) and electron energy-loss spectroscopy (EELS) microanalysis have been used to study the structural and chemcial modifications caused by interaction with the atmosphere of small, very reactive chromium (Cr) particles whose diameters range from 150 to 1300 . Analysis of the data allows us to deduce that the particles consist of a Cr core with a body-centred cubic structure and with a lattice parameter reduced by about 4% with respect to the bulk value by surface stresses (for the smallest diameter), surrounded by a Cr2O3 shell of about 15- width."
1237245,Wise et al. 1991,CLASTOGENICITY OF LEAD CHROMATE PARTICLES IN HAMSTER AND HUMAN CELLS,BIOSIS COPYRIGHT: BIOL ABS. RRM ABSTRACT GENOTOXICITY CARCINOGENESIS,CLASTOGENICITY OF LEAD CHROMATE PARTICLES IN HAMSTER AND HUMAN CELLS Abs: BIOSIS COPYRIGHT: BIOL ABS. RRM ABSTRACT GENOTOXICITY CARCINOGENESIS
1237244,Botham et al. 1991,SKIN SENSITIZATION A CRITICAL REVIEW OF PREDICTIVE TEST METHODS IN ANIMALS AND MAN,BIOSIS COPYRIGHT: BIOL ABS. RRM GUINEA-PIG MOUSE ALLERGEN CONTACT DERMATITIS HAZARDOUS MATERIALS DIAGNOSTIC TESTING GOVERNMENT REGULATION ORGANIZATION FOR ECONOMIC COOPERATION AND DEVELOPMENT OECD EEC USA JAPAN,SKIN SENSITIZATION A CRITICAL REVIEW OF PREDICTIVE TEST METHODS IN ANIMALS AND MAN Abs: BIOSIS COPYRIGHT: BIOL ABS. RRM GUINEA-PIG MOUSE ALLERGEN CONTACT DERMATITIS HAZARDOUS MATERIALS DIAGNOSTIC TESTING GOVERNMENT REGULATION ORGANIZATION FOR ECONOMIC COOPERATION AND DEVELOPMENT OECD EEC USA JAPAN
1237243,Patierno et al. 1991,MITOGENESIS AND CLASTOGENESIS OF PARTICULATE METAL CARCINOGENS IN RESPIRATORY EPITHELIAL CELLS,BIOSIS COPYRIGHT: BIOL ABS. RRM ABSTRACT HUMAN RAT MODEL NICKEL SUBSULFIDE LEAD CHROMATE DNA LESIONS,MITOGENESIS AND CLASTOGENESIS OF PARTICULATE METAL CARCINOGENS IN RESPIRATORY EPITHELIAL CELLS Abs: BIOSIS COPYRIGHT: BIOL ABS. RRM ABSTRACT HUMAN RAT MODEL NICKEL SUBSULFIDE LEAD CHROMATE DNA LESIONS
1237240,Nyholm 1991,Toxic effects on algal phosphate uptake,"BIOSIS COPYRIGHT: BIOL ABS. The inhibitory effects on growth and phosphate uptake by two toxicants, 3,5-dichlorophenol and potassium dichromate, were studied in batch culture experiments with the freshwater green alga Selenastrum capricornutum. The EC50 figures for inhibition of phosphate uptake were considerably smaller than corresponding figures for growth inhibition, but threshold toxicities did not differ as much. Toxic inhibition of phosphate uptake may potentially influence interspecies competition among phytoplankton.","Toxic effects on algal phosphate uptake Abs: BIOSIS COPYRIGHT: BIOL ABS. The inhibitory effects on growth and phosphate uptake by two toxicants, 3,5-dichlorophenol and potassium dichromate, were studied in batch culture experiments with the freshwater green alga Selenastrum capricornutum. The EC50 figures for inhibition of phosphate uptake were considerably smaller than corresponding figures for growth inhibition, but threshold toxicities did not differ as much. Toxic inhibition of phosphate uptake may potentially influence interspecies competition among phytoplankton."
1237236,Balato et al. 1991,GENERALIZED DERMATITIS DUE TO AN OSTEOSYNTHESIS SCREW,BIOSIS COPYRIGHT: BIOL ABS. RRM HUMAN POTASSIUM DICHROMATE NICKEL SULFATE COBALT CHLORIDE METALS IMPLANT ALLERGEN BIOMEDICAL INSTRUMENTATION PROSTHETIC,GENERALIZED DERMATITIS DUE TO AN OSTEOSYNTHESIS SCREW Abs: BIOSIS COPYRIGHT: BIOL ABS. RRM HUMAN POTASSIUM DICHROMATE NICKEL SULFATE COBALT CHLORIDE METALS IMPLANT ALLERGEN BIOMEDICAL INSTRUMENTATION PROSTHETIC
1237232,Brauer and  Wetterhahn 1991,Chromium(VI) forms a thiolate complex with glutathione,"BIOSIS COPYRIGHT: BIOL ABS. Reaction of potassium dichromate with the tripeptide glutathione resulted in the formation of a 1:1 complex of CrVI with glutathione. The red CrVI-glutathione adduct was stable forand 17O NMR studies showed that glutathione acts as a monodentate ligand and binds to CrVI through the cysteinyl thiolate group, forming a GSCrO3- complex. No evidence was obtained for involvement of the other possible ligating groups, e.g., glutamyl amino and carboxylate, glycinyl carboxylate, or peptide backbone, in binding to CrVI; however, CrVI-induced conformational changes in the glutamyl and cysteinyl side chains of the tripeptide. EPR studies showed that two chromium(V) species (g = 1.987 and g = 1.973) are formed upon reaction of potassium dichromate with glutathione. Chromium-glutathione complexes may be involved in producing the high levels of chromium(VI)-induced DNA damage in cells having high concentrations of glutathione and may play an important role in the carcinogenicity of c","Chromium(VI) forms a thiolate complex with glutathione Abs: BIOSIS COPYRIGHT: BIOL ABS. Reaction of potassium dichromate with the tripeptide glutathione resulted in the formation of a 1:1 complex of CrVI with glutathione. The red CrVI-glutathione adduct was stable forand 17O NMR studies showed that glutathione acts as a monodentate ligand and binds to CrVI through the cysteinyl thiolate group, forming a GSCrO3- complex. No evidence was obtained for involvement of the other possible ligating groups, e.g., glutamyl amino and carboxylate, glycinyl carboxylate, or peptide backbone, in binding to CrVI; however, CrVI-induced conformational changes in the glutamyl and cysteinyl side chains of the tripeptide. EPR studies showed that two chromium(V) species (g = 1.987 and g = 1.973) are formed upon reaction of potassium dichromate with glutathione. Chromium-glutathione complexes may be involved in producing the high levels of chromium(VI)-induced DNA damage in cells having high concentrations of glutathione and may play an important role in the carcinogenicity of c"
1237231,Okkerman et al. 1991,Ecotoxicological effects assessment: A comparison of several extrapolation procedures,"BIOSIS COPYRIGHT: BIOL ABS. In the future, extrapolation procedures will become more and more important for the effect assessment of compounds in aquatic systems. For achieving a reliable method these extrapolation procedures have to be evaluated thoroughly. As a first step three extrapolation procedures are compared by means of two sets of data, consisting of (semi)chronic and acute toxicity test results for 11 aquatic species and 8 compounds. Because of its statistical basis that extrapolation procedure of Van Straalen and Denneman is preferred over the procedures of the EPA and Stephan et al. The results of the calculations showed that lower numbers of toxicity data increase the chance of underestimating the risk of a compound. Therefore it is proposed to extend the OECD guidelines for algae, Daphnia, and fish with chronic (aquatic) toxicity tests for more species of different taxonomic groups.","Ecotoxicological effects assessment: A comparison of several extrapolation procedures Abs: BIOSIS COPYRIGHT: BIOL ABS. In the future, extrapolation procedures will become more and more important for the effect assessment of compounds in aquatic systems. For achieving a reliable method these extrapolation procedures have to be evaluated thoroughly. As a first step three extrapolation procedures are compared by means of two sets of data, consisting of (semi)chronic and acute toxicity test results for 11 aquatic species and 8 compounds. Because of its statistical basis that extrapolation procedure of Van Straalen and Denneman is preferred over the procedures of the EPA and Stephan et al. The results of the calculations showed that lower numbers of toxicity data increase the chance of underestimating the risk of a compound. Therefore it is proposed to extend the OECD guidelines for algae, Daphnia, and fish with chronic (aquatic) toxicity tests for more species of different taxonomic groups."
1237228,De Flora et al. 1990,GENOTOXICITY BIOTRANSFORMATIONS AND INTERACTIONS OF MARINE POLLUTANTS AS RELATED TO GENETIC AND CARCINOGENIC HAZARDS,BIOSIS COPYRIGHT: BIOL ABS. RRM FISH BACTERIA ANIMAL HUMAN HEALTH METABOLISM SUNLIGHT UV RADIATION OIL DISPERSANT RISK ASSESSMENT MEDITERRANEAN SEA,GENOTOXICITY BIOTRANSFORMATIONS AND INTERACTIONS OF MARINE POLLUTANTS AS RELATED TO GENETIC AND CARCINOGENIC HAZARDS Abs: BIOSIS COPYRIGHT: BIOL ABS. RRM FISH BACTERIA ANIMAL HUMAN HEALTH METABOLISM SUNLIGHT UV RADIATION OIL DISPERSANT RISK ASSESSMENT MEDITERRANEAN SEA
1237227,Grandjean 1990,ADVANCES IN APPLIED BIOTECHNOLOGY SERIES VOL. 5. CARCINOGENIC MUTAGENIC AND TERATOGENIC MARINE POLLUTANTS IMPACT ON HUMAN HEALTH AND THE ENVIRONMENT WORKSHOP ROME ITALY,BIOSIS COPYRIGHT: BIOL ABS. RRM BOOK MEETING MARINE ORGANISM UNITED NATIONS ENVIRONMENTAL PROGRAM WHO,ADVANCES IN APPLIED BIOTECHNOLOGY SERIES VOL. 5. CARCINOGENIC MUTAGENIC AND TERATOGENIC MARINE POLLUTANTS IMPACT ON HUMAN HEALTH AND THE ENVIRONMENT WORKSHOP ROME ITALY Abs: BIOSIS COPYRIGHT: BIOL ABS. RRM BOOK MEETING MARINE ORGANISM UNITED NATIONS ENVIRONMENTAL PROGRAM WHO
1237224,Kusk and  Nyholm 1991,Evaluation of a phytoplankton toxicity test for water pollution assessment and control,"BIOSIS COPYRIGHT: BIOL ABS. A suggested standard test protocol for the short term 14C assimilation algal toxicity test method (photosynthesis inhibition test) has been evaluated with natural phytoplankton and cultures of the marine diatom Skeletonema costatum. A number of test technical factors as well as the variability in the sensitivity of natural phytoplankton have been investigated, using potassium dichromate as a reference toxicant in all tests. Some supplementary experiments were carried out with pentachlorophenol and with an industrial effluent. The sensitivity of the test increased with increasing incubation time, but for practical reasons 6 hours of incubation time is recommended. The method showed good reproducibility. The sensitivity of natural phytoplankton, however, varied considerably, both between sampling locations and with time. For testing of effluents it was found necessary to measure the CO2 alkalinity and correct for changes in the specific 14C activity caused bty the deviat","Evaluation of a phytoplankton toxicity test for water pollution assessment and control Abs: BIOSIS COPYRIGHT: BIOL ABS. A suggested standard test protocol for the short term 14C assimilation algal toxicity test method (photosynthesis inhibition test) has been evaluated with natural phytoplankton and cultures of the marine diatom Skeletonema costatum. A number of test technical factors as well as the variability in the sensitivity of natural phytoplankton have been investigated, using potassium dichromate as a reference toxicant in all tests. Some supplementary experiments were carried out with pentachlorophenol and with an industrial effluent. The sensitivity of the test increased with increasing incubation time, but for practical reasons 6 hours of incubation time is recommended. The method showed good reproducibility. The sensitivity of natural phytoplankton, however, varied considerably, both between sampling locations and with time. For testing of effluents it was found necessary to measure the CO2 alkalinity and correct for changes in the specific 14C activity caused bty the deviat"
1237222,Scott et al. 1991,GENOTOXICITY UNDER EXTREME CULTURE CONDITIONS A REPORT FROM ICPEMC TASK GROUP 9,BIOSIS COPYRIGHT: BIOL ABS. RRM MAMMAL BACTERIA INTERNATIONAL COMMISSION FOR PROTECTION AGAINST ENVIRONMENTAL MUTAGENS AND CARCINOGENS CYTOTOXICITY CARCINOGENESIS,GENOTOXICITY UNDER EXTREME CULTURE CONDITIONS A REPORT FROM ICPEMC TASK GROUP 9 Abs: BIOSIS COPYRIGHT: BIOL ABS. RRM MAMMAL BACTERIA INTERNATIONAL COMMISSION FOR PROTECTION AGAINST ENVIRONMENTAL MUTAGENS AND CARCINOGENS CYTOTOXICITY CARCINOGENESIS
1237220,Oshima et al. 1991,EPIDEMIOLOGIC STUDY ON OCCUPATIONAL ALLERGY IN THE DENTAL CLINIC,BIOSIS COPYRIGHT: BIOL ABS. RRM NOTE HUMAN DENTAL PERSONNEL METALS PLASTICS HAZARDOUS MATERIALS DENTISTRY CONTACT DERMATITIS WORK ENVIRONMENT OCCUPATIONAL TOXICOLOGY,EPIDEMIOLOGIC STUDY ON OCCUPATIONAL ALLERGY IN THE DENTAL CLINIC Abs: BIOSIS COPYRIGHT: BIOL ABS. RRM NOTE HUMAN DENTAL PERSONNEL METALS PLASTICS HAZARDOUS MATERIALS DENTISTRY CONTACT DERMATITIS WORK ENVIRONMENT OCCUPATIONAL TOXICOLOGY
1237219,Sengupta et al. 1990,Effect of chromium administration on glutathione cycle of rat intestinal epithelial cells,"BIOSIS COPYRIGHT: BIOL ABS. Acute oral administration of K2Cr2O7 (1500 mg/kg body wt/day) for 3 days to rats led to the decrease in activities of glucose-6-phosphate dehydrogenase, glutathione peroxidase, glutathione reductase, glutathione-S-transferase, superoxide dismutase and catalase of intestinal epithelial cells. Glutathione and total thiol contents were decreased while lipid peroxidation was increased markedly using the whole homogenate of the intestinal epithelial cells. Chronic oral administration of K2Cr2O7 (300 mg/kg body wt/day) for 30 days to rats on the other hand, led to marked increase in superoxide dismutase and glutathione perioxidase activities with no appreciable change in glucose-6-phosphate dehydrogenase, glutathione reductase and catalase activities. However, glutathione-S-transferase activity was decreased significantly. In the whole homogenate of rat intestine, glutathione and total thiol contents were decreased not so significantly but there was a slight enhancement in lip","Effect of chromium administration on glutathione cycle of rat intestinal epithelial cells Abs: BIOSIS COPYRIGHT: BIOL ABS. Acute oral administration of K2Cr2O7 (1500 mg/kg body wt/day) for 3 days to rats led to the decrease in activities of glucose-6-phosphate dehydrogenase, glutathione peroxidase, glutathione reductase, glutathione-S-transferase, superoxide dismutase and catalase of intestinal epithelial cells. Glutathione and total thiol contents were decreased while lipid peroxidation was increased markedly using the whole homogenate of the intestinal epithelial cells. Chronic oral administration of K2Cr2O7 (300 mg/kg body wt/day) for 30 days to rats on the other hand, led to marked increase in superoxide dismutase and glutathione perioxidase activities with no appreciable change in glucose-6-phosphate dehydrogenase, glutathione reductase and catalase activities. However, glutathione-S-transferase activity was decreased significantly. In the whole homogenate of rat intestine, glutathione and total thiol contents were decreased not so significantly but there was a slight enhancement in lip"
1237214,Keefe et al. 1991,A hierarchical coding system for occupational exposure,"BIOSIS COPYRIGHT: BIOL ABS. A 10-digit hierarchical method for coding occupationally encountered chemicals offering significant advantages over existing chemical coding systems has been developed and tested. With this unique system, substances are categorized and coded according to their composition and physical natures. Consequently, compounds of similar structure may be distinguished, and classes of similar compounds (for example, all halogenated organic compounds, all inorganic sulfates) can be readily retrieved. This novel coding system was developed to assist primariy in the identification of potential carcinogens in occupational studies using job exposure matrices. However, the system has wider applications as it can be employed by industry to facilitate data management and monitoring programs in the workplace.","A hierarchical coding system for occupational exposure Abs: BIOSIS COPYRIGHT: BIOL ABS. A 10-digit hierarchical method for coding occupationally encountered chemicals offering significant advantages over existing chemical coding systems has been developed and tested. With this unique system, substances are categorized and coded according to their composition and physical natures. Consequently, compounds of similar structure may be distinguished, and classes of similar compounds (for example, all halogenated organic compounds, all inorganic sulfates) can be readily retrieved. This novel coding system was developed to assist primariy in the identification of potential carcinogens in occupational studies using job exposure matrices. However, the system has wider applications as it can be employed by industry to facilitate data management and monitoring programs in the workplace."
1237210,Lim 1990,INCIDENCE OF OCCUPATIONAL DERMATOSES STUDIED AT TWO HOSPITALS IN KOREA,BIOSIS COPYRIGHT: BIOL ABS. RRM ABSTRACT HUMAN POTASSIUM DICHROMATE NICKEL SULFATE RUBBER CHEMICALS CONTACT DERMATITIS EPIDEMIOLOGY,INCIDENCE OF OCCUPATIONAL DERMATOSES STUDIED AT TWO HOSPITALS IN KOREA Abs: BIOSIS COPYRIGHT: BIOL ABS. RRM ABSTRACT HUMAN POTASSIUM DICHROMATE NICKEL SULFATE RUBBER CHEMICALS CONTACT DERMATITIS EPIDEMIOLOGY
1237209,Manahan 1990,Hazardous waste chemistry toxicology and treatment,BIOSIS COPYRIGHT: BIOL ABS. RRM BOOK DETOXIFICATION,Hazardous waste chemistry toxicology and treatment Abs: BIOSIS COPYRIGHT: BIOL ABS. RRM BOOK DETOXIFICATION
1237208,Bragt et al. 1991,Biological monitoring of exposure to chromium(VI) salts: The role of solubility,Biosis copyright: biol abs. rrm human allergen carcinogen urine level blood level occupational exposure,Biological monitoring of exposure to chromium(VI) salts: The role of solubility Abs: Biosis copyright: biol abs. rrm human allergen carcinogen urine level blood level occupational exposure
1237207,Dillon and  Ho 1991,BIOLOGICAL MONITORING OF EXPOSURE TO CHEMICALS METALS,BIOSIS COPYRIGHT: BIOL ABS. RRM BOOK HUMAN HEAVY METAL TOXICITY HAIR ANALYSIS,BIOLOGICAL MONITORING OF EXPOSURE TO CHEMICALS METALS Abs: BIOSIS COPYRIGHT: BIOL ABS. RRM BOOK HUMAN HEAVY METAL TOXICITY HAIR ANALYSIS
1237201,Grau and  Et 1991,FIFTEENTH BIENNIAL CONFERENCE OF THE INTERNATIONAL ASSOCIATION OF WATER POLLUTION RESEARCH AND CONTROL PART 4 KYOTO JAPAN JULY 29-AUGUST 3 1990,BIOSIS COPYRIGHT: BIOL ABS. RRM MEETING WATER POLLUTION POLLUTION CONTROL,FIFTEENTH BIENNIAL CONFERENCE OF THE INTERNATIONAL ASSOCIATION OF WATER POLLUTION RESEARCH AND CONTROL PART 4 KYOTO JAPAN JULY 29-AUGUST 3 1990 Abs: BIOSIS COPYRIGHT: BIOL ABS. RRM MEETING WATER POLLUTION POLLUTION CONTROL
1237200,Ziegler and  U-F 1990,MYCOSIS FUNGOIDES A DISEASE OF CHRONIC ANTIGEN STIMULATION LONG-TERM SENSITIZATION EXPERIMENTS,BIOSIS COPYRIGHT: BIOL ABS. RRM ABSTRACT HUMAN WORKERS GUINEA-PIG POTASSIUM DICHROMATE METALS OCCUPATIONAL ALLERGEN OCCUPATIONAL TOXICOLOGY,MYCOSIS FUNGOIDES A DISEASE OF CHRONIC ANTIGEN STIMULATION LONG-TERM SENSITIZATION EXPERIMENTS Abs: BIOSIS COPYRIGHT: BIOL ABS. RRM ABSTRACT HUMAN WORKERS GUINEA-PIG POTASSIUM DICHROMATE METALS OCCUPATIONAL ALLERGEN OCCUPATIONAL TOXICOLOGY
1237199,Richter and  Solez 1990,INTERNATIONAL REVIEW OF EXPERIMENTAL PATHOLOGY VOL. 31. TRANSITION METAL TOXICITY,BIOSIS COPYRIGHT: BIOL ABS. RRM BOOK,INTERNATIONAL REVIEW OF EXPERIMENTAL PATHOLOGY VOL. 31. TRANSITION METAL TOXICITY Abs: BIOSIS COPYRIGHT: BIOL ABS. RRM BOOK
1237198,Van Leeuwen 1990,ECOTOXICOLOGICAL EFFECTS ASSESSMENT IN THE NETHERLANDS RECENT DEVELOPMENTS,BIOSIS COPYRIGHT: BIOL ABS. RRM BACTERIA PLANT ANIMAL TERRESTRIAL HABITAT SOIL AQUATIC ENVIRONMENT MATHEMATICAL METHOD DINITRO-O-CRESOL DIMETHOATE POTASSIUM BICHROMATE SODIUM BROMIDE TETRAPROPYLENEBENZENESULFONATE 2 4 DICHLOROANILINE P NITROTOLUENE PENTACHLOROPHENOL,ECOTOXICOLOGICAL EFFECTS ASSESSMENT IN THE NETHERLANDS RECENT DEVELOPMENTS Abs: BIOSIS COPYRIGHT: BIOL ABS. RRM BACTERIA PLANT ANIMAL TERRESTRIAL HABITAT SOIL AQUATIC ENVIRONMENT MATHEMATICAL METHOD DINITRO-O-CRESOL DIMETHOATE POTASSIUM BICHROMATE SODIUM BROMIDE TETRAPROPYLENEBENZENESULFONATE 2 4 DICHLOROANILINE P NITROTOLUENE PENTACHLOROPHENOL
1237196,Chester-Jones et al. 1990,Physiological and pathological effects of feeding high levels of magnesium to steers,"BIOSIS COPYRIGHT: BIOL ABS. The effects of feeding high levels of Mg were evaluated in a 130-d study with 24 steers. Six steers were allotted to each of four diets supplmented with MgO to attain .3, 1.4, 2.5 or 4.7% Mg, DM basis. Chromic oxide was used as digesta marker, fecal grab samples were collected once daily during nine consecutive 10-d periods. Steers fed 2.5 and 4.75 Mg refused some feed during the study, so their respective dietary Mg intakes were 2.4 and 3.7% (DM basis). Severe dirrhea and a lethargic appearance were observed in steers fed the two higher Mg levels. Fecal DM and apparent DM digestibility decreased linearly (P .01) with increased dietary Mg. Apparent Mg absorption (g/d) increased linearly (P .01) and apparent Ca and P absorption (g/d) decreased linearly (P .01) with addition of Mg to the diet. Increasing dietary Mg linearly elevated blood serum and erythrocyte Mg (P .01; P .05, respectively) and serum inorganic P (P .05) and linearly decreased","Physiological and pathological effects of feeding high levels of magnesium to steers Abs: BIOSIS COPYRIGHT: BIOL ABS. The effects of feeding high levels of Mg were evaluated in a 130-d study with 24 steers. Six steers were allotted to each of four diets supplmented with MgO to attain .3, 1.4, 2.5 or 4.7% Mg, DM basis. Chromic oxide was used as digesta marker, fecal grab samples were collected once daily during nine consecutive 10-d periods. Steers fed 2.5 and 4.75 Mg refused some feed during the study, so their respective dietary Mg intakes were 2.4 and 3.7% (DM basis). Severe dirrhea and a lethargic appearance were observed in steers fed the two higher Mg levels. Fecal DM and apparent DM digestibility decreased linearly (P .01) with increased dietary Mg. Apparent Mg absorption (g/d) increased linearly (P .01) and apparent Ca and P absorption (g/d) decreased linearly (P .01) with addition of Mg to the diet. Increasing dietary Mg linearly elevated blood serum and erythrocyte Mg (P .01; P .05, respectively) and serum inorganic P (P .05) and linearly decreased"
1237194,Madrid et al. 1990,"Lead hydride generation in a lactic acid-potassium dichromate medium and its application to the determination of lead in fish, vegetable and drink samples","BIOSIS COPYRIGHT: BIOL ABS. The effect of different acids on the efficiency of lead hydride generation in potassium dichromate oxidant medium was investigated and the lactic acid-potassium dichromate was found to give optimum lead hydride generation. Various parameters affecting sensitivity and the influence of interfering ions were studied. The sensitivity of the method (0.44 ng) is greater than published values for ammonium peroxodisulphate-nitric acid (20.0 ng) and hydrogen peroxide-nitric acid (10.0 ng). This could be because lactic acid stabilizes the Pb(IV) metastable compounds more effectively, acting as intermediate species in lead hydride formation. The method was applied to the determination of lead in liquids (tap water and wine) and fish and vegetable samples. The liquids were analysed directly without preconcentration or mineralization and the solids after wet digestion or slurry formation; these two sample preparation methods gave similar results.","Lead hydride generation in a lactic acid-potassium dichromate medium and its application to the determination of lead in fish, vegetable and drink samples Abs: BIOSIS COPYRIGHT: BIOL ABS. The effect of different acids on the efficiency of lead hydride generation in potassium dichromate oxidant medium was investigated and the lactic acid-potassium dichromate was found to give optimum lead hydride generation. Various parameters affecting sensitivity and the influence of interfering ions were studied. The sensitivity of the method (0.44 ng) is greater than published values for ammonium peroxodisulphate-nitric acid (20.0 ng) and hydrogen peroxide-nitric acid (10.0 ng). This could be because lactic acid stabilizes the Pb(IV) metastable compounds more effectively, acting as intermediate species in lead hydride formation. The method was applied to the determination of lead in liquids (tap water and wine) and fish and vegetable samples. The liquids were analysed directly without preconcentration or mineralization and the solids after wet digestion or slurry formation; these two sample preparation methods gave similar results."
1237193,Dive et al. 1990,Canadian workshop on the Colpidium campylum ciliate protozoan growth inhibition test,"BIOSIS COPYRIGHT: BIOL ABS. A Canadian workshop was organized to assess the standardization potential of the Colpidium campylum 24h IC50 ciliate protozoan growth inhibition test procedure. The workshop brought together a small group of invited professional and technical laboratory personnel from across Canada who had no prior knowledge of this bioassay. The work program consisted of one day of theory (general biology of the test organism, protocol analysis, demonstration of material and equipment requirements), three days of experimentation, and one day for data compilation and discussion of results. An important goal of the workshop was intended to estimate the degree of difficulty to learn and initiate this test and to strive to improve the experimental protocol after participants had experienced the bioassay. Experiments on potassium dichromate toxicity and on metal interactions (Cd:Zn and Cd:Cu) were performed in three growth media differing in their calcium and alkalinity content. While mediu","Canadian workshop on the Colpidium campylum ciliate protozoan growth inhibition test Abs: BIOSIS COPYRIGHT: BIOL ABS. A Canadian workshop was organized to assess the standardization potential of the Colpidium campylum 24h IC50 ciliate protozoan growth inhibition test procedure. The workshop brought together a small group of invited professional and technical laboratory personnel from across Canada who had no prior knowledge of this bioassay. The work program consisted of one day of theory (general biology of the test organism, protocol analysis, demonstration of material and equipment requirements), three days of experimentation, and one day for data compilation and discussion of results. An important goal of the workshop was intended to estimate the degree of difficulty to learn and initiate this test and to strive to improve the experimental protocol after participants had experienced the bioassay. Experiments on potassium dichromate toxicity and on metal interactions (Cd:Zn and Cd:Cu) were performed in three growth media differing in their calcium and alkalinity content. While mediu"
1237185,Ashby et al. 1990,OVERVIEW OF THE STUDY IN RELATION TO PROTOCOL DESIGN FOR THE RODENT BONE-MARROW MICRONUCLEUS ASSAY,BIOSIS COPYRIGHT: BIOL ABS. RRM POLYCHROMATIC ERYTHROCYTES GENOTOXICITY 28 TOXINS,OVERVIEW OF THE STUDY IN RELATION TO PROTOCOL DESIGN FOR THE RODENT BONE-MARROW MICRONUCLEUS ASSAY Abs: BIOSIS COPYRIGHT: BIOL ABS. RRM POLYCHROMATIC ERYTHROCYTES GENOTOXICITY 28 TOXINS
1237181,Guenther and  Pestemer 1990,Risk assessment for selected xenobiotics by bioassay methods with higher plants,"BIOSIS COPYRIGHT: BIOL ABS. Different bioassays with higher plants were approved for use in a bioassay procedure for testing of xenobiotics according to the German Chemicals Act. Selected environmental pollutants (atrazine, cadmium chloride, 2,6-dichlorobenzonitrile, pentachlorophenol, potassium dichromate, thiourea) all from a list of reference chemicals, were tested with these methods. Dose-response curves for growth of oats and turnips were evaluated in soil and vermiculite (non-sorptive substrate), and availability to plants was calculated by comparing the EC50 values for one chemical in both substrates. The most active chemical was atrazine, followed by 2,6-dichlorobenzonitrile, pentachlorophenol, potassium dichromate, cadmium chloride, and thiourea. The least available compound to plants was pentachlorophenol, tested with turnips (Brassica rapa va. rapa). The strongest inhibition of germination, demonstrated in an in vitro assay with garden cress (Lepidium sativum), was found with 2,6-dichlor","Risk assessment for selected xenobiotics by bioassay methods with higher plants Abs: BIOSIS COPYRIGHT: BIOL ABS. Different bioassays with higher plants were approved for use in a bioassay procedure for testing of xenobiotics according to the German Chemicals Act. Selected environmental pollutants (atrazine, cadmium chloride, 2,6-dichlorobenzonitrile, pentachlorophenol, potassium dichromate, thiourea) all from a list of reference chemicals, were tested with these methods. Dose-response curves for growth of oats and turnips were evaluated in soil and vermiculite (non-sorptive substrate), and availability to plants was calculated by comparing the EC50 values for one chemical in both substrates. The most active chemical was atrazine, followed by 2,6-dichlorobenzonitrile, pentachlorophenol, potassium dichromate, cadmium chloride, and thiourea. The least available compound to plants was pentachlorophenol, tested with turnips (Brassica rapa va. rapa). The strongest inhibition of germination, demonstrated in an in vitro assay with garden cress (Lepidium sativum), was found with 2,6-dichlor"
1237180,Otabbong 1990,Chemistry of chromium in some Swedish soils: V. Interaction between chromium trioxide and silicon hydroxide and its impact on chromium toxicity and elemental contents in ryegrass (Lolium perenne),"BIOSIS COPYRIGHT: BIOL ABS. The effect of Si(OH)4 on Cr toxicity and elemental concentrations in ryegrass were investigated in a growth chamber using an acid and a neutral mineral soil. Each soil was treated with 50 mg Cr, as CrO3, kg-1 soil dry weight, singly, or in combination with 25 mg Si as Si(OH)4. Plants growing in unamended soils were used as controls. Chromium toxicity, expressed as decrease in shoot or root dry weight, was increased by the Si. This increase was accompanied by a higher Cr uptake particularly on the acid soil. The shoot and root dry weight were significantly correlated (P = 1%) with the concentration of Cr, where r = -0.80 and -0.65, respectively. Uptake of Al, Cu, Fe, P and Zn did not show any consistent relationship to the magnitude of Cr toxicity.","Chemistry of chromium in some Swedish soils: V. Interaction between chromium trioxide and silicon hydroxide and its impact on chromium toxicity and elemental contents in ryegrass (Lolium perenne) Abs: BIOSIS COPYRIGHT: BIOL ABS. The effect of Si(OH)4 on Cr toxicity and elemental concentrations in ryegrass were investigated in a growth chamber using an acid and a neutral mineral soil. Each soil was treated with 50 mg Cr, as CrO3, kg-1 soil dry weight, singly, or in combination with 25 mg Si as Si(OH)4. Plants growing in unamended soils were used as controls. Chromium toxicity, expressed as decrease in shoot or root dry weight, was increased by the Si. This increase was accompanied by a higher Cr uptake particularly on the acid soil. The shoot and root dry weight were significantly correlated (P = 1%) with the concentration of Cr, where r = -0.80 and -0.65, respectively. Uptake of Al, Cu, Fe, P and Zn did not show any consistent relationship to the magnitude of Cr toxicity."
1237178,Tabata et al. 1990,EVALUATION OF TOXICITY OF RIVER SEDIMENTS BY IN-VITRO ENZYME INHIBITION,BIOSIS COPYRIGHT: BIOL ABS. RRM WATER POLLUTION ENVIRONMENTAL SURVEILLANCE ALKALINE PHOSPHATASE GLUCOSE-6-PHOSPHATE DEHYDROGENASE BETA GLUCURONIDASE ANALYTICAL TECHNIQUES TAMA RIVER AYASE RIVER JAPAN,EVALUATION OF TOXICITY OF RIVER SEDIMENTS BY IN-VITRO ENZYME INHIBITION Abs: BIOSIS COPYRIGHT: BIOL ABS. RRM WATER POLLUTION ENVIRONMENTAL SURVEILLANCE ALKALINE PHOSPHATASE GLUCOSE-6-PHOSPHATE DEHYDROGENASE BETA GLUCURONIDASE ANALYTICAL TECHNIQUES TAMA RIVER AYASE RIVER JAPAN
1237175,Lerman and  Kipen 1990,MATERIAL SAFETY DATA SHEETS CAVEAT EMPTOR,BIOSIS COPYRIGHT: BIOL ABS. RRM HUMAN HAZARDOUS CHEMICALS TOXICITY LEGISLATION,MATERIAL SAFETY DATA SHEETS CAVEAT EMPTOR Abs: BIOSIS COPYRIGHT: BIOL ABS. RRM HUMAN HAZARDOUS CHEMICALS TOXICITY LEGISLATION
1237172,Shigeto et al. 1989,Metal hypersensitivity in dentists: A patch test study,"BIOSIS COPYRIGHT: BIOL ABS. Patch test of dental alloys was conducted on dentists in the Department of Prosthetic Dentistry, Hiroshima University School of Dentistry. The positive rate of the first patch test in the test group was 47.1%, and that in the control group was 10.0%, showing a large difference between the two groups. Furthermore, a second patch test was conducted on those who showed a positive response together with pustular or follicular reaction. As neither positive response nor pustular or follicular reaction was observed in the second patch test, the results were regarded as negative. Only a very slight difference in the positive rate could be observed when the results of the two tests were combined. The results of the present study suggest that the possibility is small for dentists to develop metal hypersensitivity in normal clinical practice.","Metal hypersensitivity in dentists: A patch test study Abs: BIOSIS COPYRIGHT: BIOL ABS. Patch test of dental alloys was conducted on dentists in the Department of Prosthetic Dentistry, Hiroshima University School of Dentistry. The positive rate of the first patch test in the test group was 47.1%, and that in the control group was 10.0%, showing a large difference between the two groups. Furthermore, a second patch test was conducted on those who showed a positive response together with pustular or follicular reaction. As neither positive response nor pustular or follicular reaction was observed in the second patch test, the results were regarded as negative. Only a very slight difference in the positive rate could be observed when the results of the two tests were combined. The results of the present study suggest that the possibility is small for dentists to develop metal hypersensitivity in normal clinical practice."
1237168,Howard et al. 1990,Influence of chromium compounds in causing chromosome changes in cultured CHO cells,,Influence of chromium compounds in causing chromosome changes in cultured CHO cells Abs: 
1237167,Comm EUR 1989,MEASUREMENT TECHNIQUES FOR CARCINOGENIC AGENTS IN WORKPLACE AIR,BIOSIS COPYRIGHT: BIOL ABS. RRM BOOK,MEASUREMENT TECHNIQUES FOR CARCINOGENIC AGENTS IN WORKPLACE AIR Abs: BIOSIS COPYRIGHT: BIOL ABS. RRM BOOK
1237166,De Flora et al. 1990,Genotoxicity of chromium compounds. A review,"This article reviews approximately 700 results reported in the literature with 32 chromium compounds assayed in 130 short-term tests, using different targets and/or genetic end-points. The large majority of the results obtained with Cr(VI) compounds were positive, as a function of Cr(VI) solubility and bioavailability to target cells. On the other hand, Cr(III) compounds, although even more reactive than Cr(VI) with purified nucleic acids, did not induce genotoxic effects in the majority of studies using intact cells. Coupled with the findings of metabolic studies, the large data-base generated in short-term test systems provides useful information for predicting and interpreting the peculiar patterns of Cr(VI) carcinogenicity.","Genotoxicity of chromium compounds. A review Abs: This article reviews approximately 700 results reported in the literature with 32 chromium compounds assayed in 130 short-term tests, using different targets and/or genetic end-points. The large majority of the results obtained with Cr(VI) compounds were positive, as a function of Cr(VI) solubility and bioavailability to target cells. On the other hand, Cr(III) compounds, although even more reactive than Cr(VI) with purified nucleic acids, did not induce genotoxic effects in the majority of studies using intact cells. Coupled with the findings of metabolic studies, the large data-base generated in short-term test systems provides useful information for predicting and interpreting the peculiar patterns of Cr(VI) carcinogenicity."
1237162,Meenakshi et al. 1989,Comparative toxicity of trivalent and hexavalent chromium in rats,"BIOSIS COPYRIGHT: BIOL ABS. The effects of trivalent and hexavalent chromium compounds in rats were studied with a view to investigate the toxic potentials of two different forms of chromium. Male albino rats were fed by gavage 10 mg Cr/kg body weight/day as solutions of chromic chloride (Cr+3) or potassium dichromate (Cr+6) in different groups for a period of sixty days. Both forms of chromium produced hepatic and renal damages, Cr++6 being more toxic than trivalent chromium. The increase in blood glucose (71 and 57%) urea (88 and 115%) and serum lipid variations were observed during Cr+3 and Cr+6 treatments respectively. Increased activities of serum transaminases and gamma-glutamyl transferase reflected the hepatic damage caused by the metal. Histological lesions in liver and kidney supported the biochemical findings with chromium treatment for a long period in experimental rats.","Comparative toxicity of trivalent and hexavalent chromium in rats Abs: BIOSIS COPYRIGHT: BIOL ABS. The effects of trivalent and hexavalent chromium compounds in rats were studied with a view to investigate the toxic potentials of two different forms of chromium. Male albino rats were fed by gavage 10 mg Cr/kg body weight/day as solutions of chromic chloride (Cr+3) or potassium dichromate (Cr+6) in different groups for a period of sixty days. Both forms of chromium produced hepatic and renal damages, Cr++6 being more toxic than trivalent chromium. The increase in blood glucose (71 and 57%) urea (88 and 115%) and serum lipid variations were observed during Cr+3 and Cr+6 treatments respectively. Increased activities of serum transaminases and gamma-glutamyl transferase reflected the hepatic damage caused by the metal. Histological lesions in liver and kidney supported the biochemical findings with chromium treatment for a long period in experimental rats."
1237160,Kahn et al. 1990,The influence of altered anticorrosion treatment on the microflora of activated sludge in petrochemical plant effluent,"BIOSIS COPYRIGHT: BIOL ABS. Representative samples from the fully aerated activated sludge basins of the water reclamation system of a zero-effluent coal-gasification petrochemical plant were monitored before and after substitution of zinc acrylate for zinc chromate as anticorrosion agent. Fluctuations in the magnitude and metabolic activity of the microbiological population of the activated sludge during this period were quantified. The use of selective and enrichment media showed that fungi, yeasts and green algae were present in insignificant numbers. Generalised counting media and a niche-simulating medium showed that the population of the activated sludge largely comprised heterotrophic bacteria representing a narrow range of genera, two filamentous microorganisms and one genus representing the cyanobacteria. The genus diversity of heterotropic bacteria increased after substitution of zinc acrylate for zinc chromate and glucose dehydrogenase activity of the sludge increased. Six weeks later ge","The influence of altered anticorrosion treatment on the microflora of activated sludge in petrochemical plant effluent Abs: BIOSIS COPYRIGHT: BIOL ABS. Representative samples from the fully aerated activated sludge basins of the water reclamation system of a zero-effluent coal-gasification petrochemical plant were monitored before and after substitution of zinc acrylate for zinc chromate as anticorrosion agent. Fluctuations in the magnitude and metabolic activity of the microbiological population of the activated sludge during this period were quantified. The use of selective and enrichment media showed that fungi, yeasts and green algae were present in insignificant numbers. Generalised counting media and a niche-simulating medium showed that the population of the activated sludge largely comprised heterotrophic bacteria representing a narrow range of genera, two filamentous microorganisms and one genus representing the cyanobacteria. The genus diversity of heterotropic bacteria increased after substitution of zinc acrylate for zinc chromate and glucose dehydrogenase activity of the sludge increased. Six weeks later ge"
1237158,Koh et al. 1990,DERMATOLOGICAL HAZARDS IN THE ELECTRONICS INDUSTRY,BIOSIS COPYRIGHT: BIOL ABS. RRM HUMAN OCCUPATIONAL HEALTH AND SAFETY OCCUPATIONAL TOXICOLOGY ALLERGEN IRRITANT DERMATOSES,DERMATOLOGICAL HAZARDS IN THE ELECTRONICS INDUSTRY Abs: BIOSIS COPYRIGHT: BIOL ABS. RRM HUMAN OCCUPATIONAL HEALTH AND SAFETY OCCUPATIONAL TOXICOLOGY ALLERGEN IRRITANT DERMATOSES
1237156,Lindgaard-Jorgensen and  Riemann 1989,Tritiated thymidine incorporation preliminary investigations of a method to forecast the toxicity of chemicals in biodegradability tests,"BIOSIS COPYRIGHT: BIOL ABS. In biodegradability tests it is essential that true non-biodegradability can be distinguished from inhibited biodegradability. Presently none of the microbial toxicity test methods available consistently forecast toxicity in the biodegradability tests, probably because the toxicity tests do not reflect the conditions in the biodegradability test methods. In this study we tested 3,5-dichlorophenol and potassiumdichromate, two chemicals often used as reference substances in microbial toxicity tests, by means of the 3H-thymidine incorporation methods and three standardized test methods. Using natural bacterial assemblages from activated sludge, freshwater and seawater we found that eutrophic bacteria were less sensitive than oligotrophic bacteria towards both test chemicals in the 3H-thymidine incorporation. Previous observations of biodegradability of dichlorophenols at the 10-20 mg liter level showing degradability in activated sludge and nonbiodegradability in seawater","Tritiated thymidine incorporation preliminary investigations of a method to forecast the toxicity of chemicals in biodegradability tests Abs: BIOSIS COPYRIGHT: BIOL ABS. In biodegradability tests it is essential that true non-biodegradability can be distinguished from inhibited biodegradability. Presently none of the microbial toxicity test methods available consistently forecast toxicity in the biodegradability tests, probably because the toxicity tests do not reflect the conditions in the biodegradability test methods. In this study we tested 3,5-dichlorophenol and potassiumdichromate, two chemicals often used as reference substances in microbial toxicity tests, by means of the 3H-thymidine incorporation methods and three standardized test methods. Using natural bacterial assemblages from activated sludge, freshwater and seawater we found that eutrophic bacteria were less sensitive than oligotrophic bacteria towards both test chemicals in the 3H-thymidine incorporation. Previous observations of biodegradability of dichlorophenols at the 10-20 mg liter level showing degradability in activated sludge and nonbiodegradability in seawater"
1237153,Dabrowski and  Kock 1989,Absorption of ascorbic acid and ascorbic sulfate and their interaction with minerals in the digestive tract of rainbow trout (Oncorhynchus mykiss),"BIOSIS COPYRIGHT: BIOL ABS. The sites of absorption of ascorbic acid (AA) in the rainbow trout (Oncorhynchus mykiss) gut were located in the stomach (20.7%), pyloric caecae region (23.4%), middle intestine (21.9%) and posterior intestine (20.1%). Ascorbic sulfate (AS) were found to be absorbed in the stomach (27.7%) although it is likely that the figure obtained is an overestimate. This conclusion is based on the concentration factor of the intestinal contents (faeces/food ratio) being much higher for ascorbic sulfate than for an external dietary marker, chromic oxide. The apparent protein absorption rates from the three diets used were not significantly different (P 0.01), ranging from 86.9 to 91.5%. Three subsequent samplings, one week apart, did not reveal changes in AA or AS absorption in trout, suggesting that fish were neither ""saturated"" with AA nor had they developed the means to utilize the dietary AS. In most cases, the mineral contents in faeces were similar for all diets, although","Absorption of ascorbic acid and ascorbic sulfate and their interaction with minerals in the digestive tract of rainbow trout (Oncorhynchus mykiss) Abs: BIOSIS COPYRIGHT: BIOL ABS. The sites of absorption of ascorbic acid (AA) in the rainbow trout (Oncorhynchus mykiss) gut were located in the stomach (20.7%), pyloric caecae region (23.4%), middle intestine (21.9%) and posterior intestine (20.1%). Ascorbic sulfate (AS) were found to be absorbed in the stomach (27.7%) although it is likely that the figure obtained is an overestimate. This conclusion is based on the concentration factor of the intestinal contents (faeces/food ratio) being much higher for ascorbic sulfate than for an external dietary marker, chromic oxide. The apparent protein absorption rates from the three diets used were not significantly different (P 0.01), ranging from 86.9 to 91.5%. Three subsequent samplings, one week apart, did not reveal changes in AA or AS absorption in trout, suggesting that fish were neither ""saturated"" with AA nor had they developed the means to utilize the dietary AS. In most cases, the mineral contents in faeces were similar for all diets, although"
1237152,Borzelleca et al. 1989,SHORT-TERM TOXICITY ONE AND TEN-DAY GAVAGE OF POTASSIUM DICHROMATE IN MALE AND FEMALE RATS,BIOSIS COPYRIGHT: BIOL ABS. RRM HUMAN ANIMAL MODEL DRINKING WATER,SHORT-TERM TOXICITY ONE AND TEN-DAY GAVAGE OF POTASSIUM DICHROMATE IN MALE AND FEMALE RATS Abs: BIOSIS COPYRIGHT: BIOL ABS. RRM HUMAN ANIMAL MODEL DRINKING WATER
1237150,Snyder et al. 1989,INHIBITION BY METALS OF X-RAY AND UV INDUCED DNA REPAIR IN HUMAN CELLS,BIOSIS COPYRIGHT: BIOL ABS. RRM,INHIBITION BY METALS OF X-RAY AND UV INDUCED DNA REPAIR IN HUMAN CELLS Abs: BIOSIS COPYRIGHT: BIOL ABS. RRM
1237142,Komori et al. 1989,FACTORS AFFECTING CHROMATE REDUCTION IN ENTEROBACTER-CLOACAE STRAIN HO1,BIOSIS COPYRIGHT: BIOL ABS. RRM TEMPERATURE PH ELECTRON DONORS CELL VIABILITY METABOLIC POISONS TOXICITY POLLUTION CONTROL,FACTORS AFFECTING CHROMATE REDUCTION IN ENTEROBACTER-CLOACAE STRAIN HO1 Abs: BIOSIS COPYRIGHT: BIOL ABS. RRM TEMPERATURE PH ELECTRON DONORS CELL VIABILITY METABOLIC POISONS TOXICITY POLLUTION CONTROL
1237138,Landolph 1989,CHEMICAL TRANSFORMATION IN C3H-10T1-2-CL-8 MOUSE EMBRYO CELLS AND DIPLOID HUMAN FIBROBLASTS,BIOSIS COPYRIGHT: BIOL ABS. RRM ABSTRACT BENZO-A-PYRENE 3 METHYLCHOLANTHRENE N ACETOXYACETYLAMINOFLUORENE LEAD CHROMATE NICKEL SUBSULFIDE NICKEL OXIDE SODIUM ARSENITE,CHEMICAL TRANSFORMATION IN C3H-10T1-2-CL-8 MOUSE EMBRYO CELLS AND DIPLOID HUMAN FIBROBLASTS Abs: BIOSIS COPYRIGHT: BIOL ABS. RRM ABSTRACT BENZO-A-PYRENE 3 METHYLCHOLANTHRENE N ACETOXYACETYLAMINOFLUORENE LEAD CHROMATE NICKEL SUBSULFIDE NICKEL OXIDE SODIUM ARSENITE
1237137,Cowgill et al. 1989,TOXICITY OF NINE BENCHMARK CHEMICALS TO SKELETONEMA-COSTATUM A MARINE DIATOM,BIOSIS COPYRIGHT: BIOL ABS. RRM SELENASTRUM-CAPRICORNUTUM POTASSIUM CHROMATE DIETHANOLAMINE 4 CHLOROPHENOL PHENOL CHLOROBENZENE CHLOROFORM ACETONE ETHANOL TRICLOPYR TRIETHYLAMINE SALT HERBICIDE,TOXICITY OF NINE BENCHMARK CHEMICALS TO SKELETONEMA-COSTATUM A MARINE DIATOM Abs: BIOSIS COPYRIGHT: BIOL ABS. RRM SELENASTRUM-CAPRICORNUTUM POTASSIUM CHROMATE DIETHANOLAMINE 4 CHLOROPHENOL PHENOL CHLOROBENZENE CHLOROFORM ACETONE ETHANOL TRICLOPYR TRIETHYLAMINE SALT HERBICIDE
1237131,Kuehn et al. 1989,RESULTS OF THE HARMFUL EFFECTS OF WATER POLLUTANTS TO DAPHNIA-MAGNA IN THE 21 DAY REPRODUCTION TEST,BIOSIS COPYRIGHT: BIOL ABS. RRM WATER POLLUTION ETHYL PARATHION BISTRI-N-BUTYLTINOXIDE CADMIUM ION,RESULTS OF THE HARMFUL EFFECTS OF WATER POLLUTANTS TO DAPHNIA-MAGNA IN THE 21 DAY REPRODUCTION TEST Abs: BIOSIS COPYRIGHT: BIOL ABS. RRM WATER POLLUTION ETHYL PARATHION BISTRI-N-BUTYLTINOXIDE CADMIUM ION
1237126,Otabbong 1989,CHEMISTRY OF CHROMIUM IN SOME SWEDISH SOILS 4. INFLUENCE OF CHROMIUM TRIOXIDE AND MONOBASIC POTASSIUM PHOSPHATE ON UPTAKE AND TRANSLOCATION OF MANGANESE COPPER ZINC IRON AND ALUMINUM OF RYE GRASS LOLIUM-PERENNE,BIOSIS COPYRIGHT: BIOL ABS. RRM RESOURCE ALLOCATION ACCUMULATION CHLOROSIS TOXICITY POLLUTANT,CHEMISTRY OF CHROMIUM IN SOME SWEDISH SOILS 4. INFLUENCE OF CHROMIUM TRIOXIDE AND MONOBASIC POTASSIUM PHOSPHATE ON UPTAKE AND TRANSLOCATION OF MANGANESE COPPER ZINC IRON AND ALUMINUM OF RYE GRASS LOLIUM-PERENNE Abs: BIOSIS COPYRIGHT: BIOL ABS. RRM RESOURCE ALLOCATION ACCUMULATION CHLOROSIS TOXICITY POLLUTANT
1237125,Liu et al. 1989,RAPID TOXICITY ASSESSMENT OF WATER-SOLUBLE AND WATER-INSOLUBLE CHEMICALS USING A MODIFIED AGAR PLATE METHOD,BIOSIS COPYRIGHT: BIOL ABS. RRM BACTERIA ORGANICS INORGANICS ORGANOMETALLICS ENVIRONMENTAL CONTAMINANTS POLLUTION EPA,RAPID TOXICITY ASSESSMENT OF WATER-SOLUBLE AND WATER-INSOLUBLE CHEMICALS USING A MODIFIED AGAR PLATE METHOD Abs: BIOSIS COPYRIGHT: BIOL ABS. RRM BACTERIA ORGANICS INORGANICS ORGANOMETALLICS ENVIRONMENTAL CONTAMINANTS POLLUTION EPA
1237123,De Boer et al. 1989,DERMATOSES IN METAL WORKERS II. ALLERGIC CONTACT DERMATITIS,BIOSIS COPYRIGHT: BIOL ABS. RRM METALWORKING FLUIDS EPIDEMIOLOGY BIOCIDE CORROSION INHIBITORS METAL INDUSTRY OCCUPATIONAL HEALTH AND SAFETY HAZARDOUS MATERIALS CONTACT SENSITIZATION,DERMATOSES IN METAL WORKERS II. ALLERGIC CONTACT DERMATITIS Abs: BIOSIS COPYRIGHT: BIOL ABS. RRM METALWORKING FLUIDS EPIDEMIOLOGY BIOCIDE CORROSION INHIBITORS METAL INDUSTRY OCCUPATIONAL HEALTH AND SAFETY HAZARDOUS MATERIALS CONTACT SENSITIZATION
1237117,Michael and  Meeks 1989,Sequestration of inulin in the kidneys of rats with acute renal failure ARF induced by potassium dichromate,,Sequestration of inulin in the kidneys of rats with acute renal failure ARF induced by potassium dichromate Abs: 
1237116,Persoone et al. 1989,PREDICTIVE VALUE OF LABORATORY TESTS WITH AQUATIC INVERTEBRATES INFLUENCE OF EXPERIMENTAL CONDITIONS,BIOSIS COPYRIGHT: BIOL ABS. RRM BRACHIONUS-PLICATILIS ARTEMIA-SALINA DAPHNIA-MAGNA HAZARD ASSESSMENT TOXICITY POTASSIUM DICHROMATE SODIUM LAURYLSULFATE TEMPERATURE SALINITY MARINE BRACKISH FRESH WATER,PREDICTIVE VALUE OF LABORATORY TESTS WITH AQUATIC INVERTEBRATES INFLUENCE OF EXPERIMENTAL CONDITIONS Abs: BIOSIS COPYRIGHT: BIOL ABS. RRM BRACHIONUS-PLICATILIS ARTEMIA-SALINA DAPHNIA-MAGNA HAZARD ASSESSMENT TOXICITY POTASSIUM DICHROMATE SODIUM LAURYLSULFATE TEMPERATURE SALINITY MARINE BRACKISH FRESH WATER
1237110,Bretschneider et al. 1989,CHARACTERIZATION OF EXPOSURE TO POLLUTANTS IN SPRAY PAINTING PLANTS BY THE USE OF INDOOR AIR CONCENTRATION RATES AND EXPOSITION TESTS,BIOSIS COPYRIGHT: BIOL ABS. RRM LEAD CHROMATE,CHARACTERIZATION OF EXPOSURE TO POLLUTANTS IN SPRAY PAINTING PLANTS BY THE USE OF INDOOR AIR CONCENTRATION RATES AND EXPOSITION TESTS Abs: BIOSIS COPYRIGHT: BIOL ABS. RRM LEAD CHROMATE
1237109,Liden 1989,OCCUPATION DERMATOSES AT A FILM LABORATORY FOLLOW-UP AFTER MODERNIZATION,BIOSIS COPYRIGHT: BIOL ABS. RRM WORKERS ALLERGIC CONTACT DERMATITIS METAL P METHYLAMINOPHENOL SULFATE HYDROQUINONE OCCUPATIONAL TOXICOLOGY HAZARDOUS MATERIALS,OCCUPATION DERMATOSES AT A FILM LABORATORY FOLLOW-UP AFTER MODERNIZATION Abs: BIOSIS COPYRIGHT: BIOL ABS. RRM WORKERS ALLERGIC CONTACT DERMATITIS METAL P METHYLAMINOPHENOL SULFATE HYDROQUINONE OCCUPATIONAL TOXICOLOGY HAZARDOUS MATERIALS
1237108,Triger et al. 1989,TRACE ELEMENT LEVELS IN THE BLOOD OF WORKERS IN TWO STEEL WORKS AND A NON-FERROUS PLANT HANDLING LEAD AND CADMIUM COMPARED WITH A NON-EXPOSED POPULATION,BIOSIS COPYRIGHT: BIOL ABS. RRM IRON CHROMIUM,TRACE ELEMENT LEVELS IN THE BLOOD OF WORKERS IN TWO STEEL WORKS AND A NON-FERROUS PLANT HANDLING LEAD AND CADMIUM COMPARED WITH A NON-EXPOSED POPULATION Abs: BIOSIS COPYRIGHT: BIOL ABS. RRM IRON CHROMIUM
1237106,Stranger-Johannessen 1988,THE ANTIMICROBIAL EFFECT OF PIGMENTS IN CORROSION PROTECTIVE PAINTS,BIOSIS COPYRIGHT: BIOL ABS. RRM ADHESION LOSS BLISTERING ZINC CHROMATE ZINC BORATE ZINC PHOSPHATE FUNGI BACTERIA,THE ANTIMICROBIAL EFFECT OF PIGMENTS IN CORROSION PROTECTIVE PAINTS Abs: BIOSIS COPYRIGHT: BIOL ABS. RRM ADHESION LOSS BLISTERING ZINC CHROMATE ZINC BORATE ZINC PHOSPHATE FUNGI BACTERIA
1237102,Sakai et al. 1988,Effect of several metal compounds on the mutagenicity and DNA binding of 1 nitropyrene in Salmonella-typhimurium TA100,"The pretreatment of the cells with cobaltous acetate, potassium dichromate or zinc chloride was found to increase reverse mutations induced by 1-nitropyrene (1-NP) and binding of 1-NP to deoxyribonucleic acid (DNA) in Salmonella typhimurium TA100. The increase of binding of 1-NP to DNA by metal compounds may contribute to the increased mutagenicity. Under the experimental conditions, the pretreatment of the cells with cadmium acetate, nickelous acetate or chromium (III) nitrate did not increase revertant colonies induced by 1-NP.","Effect of several metal compounds on the mutagenicity and DNA binding of 1 nitropyrene in Salmonella-typhimurium TA100 Abs: The pretreatment of the cells with cobaltous acetate, potassium dichromate or zinc chloride was found to increase reverse mutations induced by 1-nitropyrene (1-NP) and binding of 1-NP to deoxyribonucleic acid (DNA) in Salmonella typhimurium TA100. The increase of binding of 1-NP to DNA by metal compounds may contribute to the increased mutagenicity. Under the experimental conditions, the pretreatment of the cells with cadmium acetate, nickelous acetate or chromium (III) nitrate did not increase revertant colonies induced by 1-NP."
1237101,Ueno et al. 1988,The relationship between the development of toxicity and lipid peroxidation induced by chromium compounds in rats,,The relationship between the development of toxicity and lipid peroxidation induced by chromium compounds in rats Abs: 
1237099,De Marco et al. 1988,INDUCTION OF MICRONUCLEI IN VICIA-FABA ROOT TIPS TREATED WITH HEAVY METALS CADMIUM AND CHROMIUM IN THE PRESENCE OF NTA,BIOSIS COPYRIGHT: BIOL ABS. RRM NITRILOTRIACETIC ACID MUTAGEN ENVIRONMENTAL POLLUTANT CARCINOGEN,INDUCTION OF MICRONUCLEI IN VICIA-FABA ROOT TIPS TREATED WITH HEAVY METALS CADMIUM AND CHROMIUM IN THE PRESENCE OF NTA Abs: BIOSIS COPYRIGHT: BIOL ABS. RRM NITRILOTRIACETIC ACID MUTAGEN ENVIRONMENTAL POLLUTANT CARCINOGEN
1237097,Zamorani et al. 1988,PHYSICAL PROPERTIES MEASUREMENTS AND LEACHING BEHAVIOR OF CHROMIUM COMPOUNDS SOLIDIFIED IN A CEMENT MATRIX,BIOSIS COPYRIGHT: BIOL ABS. RRM TOXIC WASTE DISPOSAL,PHYSICAL PROPERTIES MEASUREMENTS AND LEACHING BEHAVIOR OF CHROMIUM COMPOUNDS SOLIDIFIED IN A CEMENT MATRIX Abs: BIOSIS COPYRIGHT: BIOL ABS. RRM TOXIC WASTE DISPOSAL
1237093,Lanfranchi et al. 1988,Mammalian cell transformation induced by chromium-VI compounds in the presence of nitrilotriacetic acid NTA,,Mammalian cell transformation induced by chromium-VI compounds in the presence of nitrilotriacetic acid NTA Abs: 
1237092,Celotti et al. 1988,INTERACTIONS OF NITRILOTRIACETIC ACID NTA WITH CHROMIUM-VI COMPOUNDS IN THE INDUCTION OF GENE MUTATIONS IN CULTURED MAMMALIAN CELLS,BIOSIS COPYRIGHT: BIOL ABS. RRM ABSTRACT V79 CELL LINE TOXICODYNAMICS CARCINOGEN,INTERACTIONS OF NITRILOTRIACETIC ACID NTA WITH CHROMIUM-VI COMPOUNDS IN THE INDUCTION OF GENE MUTATIONS IN CULTURED MAMMALIAN CELLS Abs: BIOSIS COPYRIGHT: BIOL ABS. RRM ABSTRACT V79 CELL LINE TOXICODYNAMICS CARCINOGEN
1237091,Langard 1988,CHROMIUM CARCINOGENICITY A REVIEW OF EXPERIMENTAL ANIMAL DATA,BIOSIS COPYRIGHT: BIOL ABS. RRM REVIEW HUMAN ANIMALS CARCINOGEN CALCIUM CHROMATE LEAD CHROMATE STRONTIUM CHROMATE ZINC POTASSIUM CHROMATE CHROMIUM TRIOXIDE LUNG CANCER,CHROMIUM CARCINOGENICITY A REVIEW OF EXPERIMENTAL ANIMAL DATA Abs: BIOSIS COPYRIGHT: BIOL ABS. RRM REVIEW HUMAN ANIMALS CARCINOGEN CALCIUM CHROMATE LEAD CHROMATE STRONTIUM CHROMATE ZINC POTASSIUM CHROMATE CHROMIUM TRIOXIDE LUNG CANCER
1237086,Young et al. 1988,AGE AND SEX DISTRIBUTION OF THE INCIDENCE OF CONTACT SENSITIVITY TO STANDARD ALLERGENS,BIOSIS COPYRIGHT: BIOL ABS. RRM HUMAN EPIDEMIOLOGY SEX DIFFERENCES COBALT NICKEL CHROMATE BALSAM OF PERU CARBA-MIX COLOPHONY FRAGRANCES WOOD TARS,AGE AND SEX DISTRIBUTION OF THE INCIDENCE OF CONTACT SENSITIVITY TO STANDARD ALLERGENS Abs: BIOSIS COPYRIGHT: BIOL ABS. RRM HUMAN EPIDEMIOLOGY SEX DIFFERENCES COBALT NICKEL CHROMATE BALSAM OF PERU CARBA-MIX COLOPHONY FRAGRANCES WOOD TARS
1237081,Ueda et al. 1988,EFFECT OF CHROMATE AND ORGANIC AMENDMENTS ON THE COMPOSITION AND ACTIVITY OF THE MICROORGANISM FLORA IN SOIL,BIOSIS COPYRIGHT: BIOL ABS. RRM FUNGI BACTERIA SOIL BIOLOGY SOIL CHEMISTRY WASTE MANAGEMENT FERTILIZER COMPOST HEAVY METAL CONTAMINATION CARBON DIOXIDE EVOLUTION DECOMPOSITION,EFFECT OF CHROMATE AND ORGANIC AMENDMENTS ON THE COMPOSITION AND ACTIVITY OF THE MICROORGANISM FLORA IN SOIL Abs: BIOSIS COPYRIGHT: BIOL ABS. RRM FUNGI BACTERIA SOIL BIOLOGY SOIL CHEMISTRY WASTE MANAGEMENT FERTILIZER COMPOST HEAVY METAL CONTAMINATION CARBON DIOXIDE EVOLUTION DECOMPOSITION
1237080,Stern et al. 1988,IN-VITRO TOXICITY OF WELDING FUMES AND THEIR CONSTITUENTS,BIOSIS COPYRIGHT: BIOL ABS. RRM BABY HAMSTER KIDNEY CELLS SYRIAN HAMSTER EMBRYO CELLS HUMAN OCCUPATIONAL EXPOSURE RISK,IN-VITRO TOXICITY OF WELDING FUMES AND THEIR CONSTITUENTS Abs: BIOSIS COPYRIGHT: BIOL ABS. RRM BABY HAMSTER KIDNEY CELLS SYRIAN HAMSTER EMBRYO CELLS HUMAN OCCUPATIONAL EXPOSURE RISK
1237073,Verriopoulos et al. 1988,JOINT EFFECTS OF FOUR POLLUTANTS COPPER CHROMIUM OIL OIL DISPERSANT ON THE RESPIRATION OF ARTEMIA,BIOSIS COPYRIGHT: BIOL ABS. RRM MEDIAN LETHAL CONCENTRATION TOXICITY RESPIRATORY RATE,JOINT EFFECTS OF FOUR POLLUTANTS COPPER CHROMIUM OIL OIL DISPERSANT ON THE RESPIRATION OF ARTEMIA Abs: BIOSIS COPYRIGHT: BIOL ABS. RRM MEDIAN LETHAL CONCENTRATION TOXICITY RESPIRATORY RATE
1237071,Berk et al. 1987,HEAVY METAL TOXICITY ON A BLUE-GREEN ALGA,BIOSIS COPYRIGHT: BIOL ABS. RRM ANABAENA-FLOS-AQUAE GROWTH MERCURY-II CHROMIUM-VI ARSENIC-V,HEAVY METAL TOXICITY ON A BLUE-GREEN ALGA Abs: BIOSIS COPYRIGHT: BIOL ABS. RRM ANABAENA-FLOS-AQUAE GROWTH MERCURY-II CHROMIUM-VI ARSENIC-V
1237069,M-A et al. 1987,HAZARDOUS CHEMICALS INFORMATION AND DISPOSAL GUIDE THIRD EDITION,BIOSIS COPYRIGHT: BIOL ABS. RRM HAZARDOUS WASTE HAZARDOUS MATERIALS WASTE MANAGEMENT,HAZARDOUS CHEMICALS INFORMATION AND DISPOSAL GUIDE THIRD EDITION Abs: BIOSIS COPYRIGHT: BIOL ABS. RRM HAZARDOUS WASTE HAZARDOUS MATERIALS WASTE MANAGEMENT
1237067,Klock et al. 1988,ACUTE INTOXICATIONS CAUSED BY PRODUCTS OF THE COLOR AND LACQUER-INDUSTRY,BIOSIS COPYRIGHT: BIOL ABS. RRM HUMAN SOLVENTS THINNERS PAINTS,ACUTE INTOXICATIONS CAUSED BY PRODUCTS OF THE COLOR AND LACQUER-INDUSTRY Abs: BIOSIS COPYRIGHT: BIOL ABS. RRM HUMAN SOLVENTS THINNERS PAINTS
1237066,Braun et al. 1987,Uses of gamma glutamyltransferase in experimental toxicology,BIOSIS COPYRIGHT: BIOL ABS. RRM HUMAN RAT RABBIT DOG MOUSE KIDNEY CARCINOGENESIS,Uses of gamma glutamyltransferase in experimental toxicology Abs: BIOSIS COPYRIGHT: BIOL ABS. RRM HUMAN RAT RABBIT DOG MOUSE KIDNEY CARCINOGENESIS
1237062,Imai 1987,TOXIC EFFECTS OF LEAD CHROMATE EXPOSURE ON RENAL TUBULES,BIOSIS COPYRIGHT: BIOL ABS. RRM HUMAN OCCUPATIONAL EXPOSURE,TOXIC EFFECTS OF LEAD CHROMATE EXPOSURE ON RENAL TUBULES Abs: BIOSIS COPYRIGHT: BIOL ABS. RRM HUMAN OCCUPATIONAL EXPOSURE
1237056,Biggart and  Murphy E 1988,ANALYSIS OF METAL-INDUCED MUTATIONS ALTERING THE EXPRESSION OR STRUCTURE OF A RETROVIRAL GENE IN A MAMMALIAN CELL LINE,BIOSIS COPYRIGHT: BIOL ABS. RRM MURINE MOLONEY MURINE SARCOMA NICKEL CHLORIDE CADMIUM CHLORIDE SODIUM CHROMATE N NITROSO-N-METHYLUREA DNA DAMAGE CARCINOGEN,ANALYSIS OF METAL-INDUCED MUTATIONS ALTERING THE EXPRESSION OR STRUCTURE OF A RETROVIRAL GENE IN A MAMMALIAN CELL LINE Abs: BIOSIS COPYRIGHT: BIOL ABS. RRM MURINE MOLONEY MURINE SARCOMA NICKEL CHLORIDE CADMIUM CHLORIDE SODIUM CHROMATE N NITROSO-N-METHYLUREA DNA DAMAGE CARCINOGEN
1237055,Chorvatovicova 1987,Synergic effects on chromosome aberration frequency of chromium and nickel ions in vivo,BIOSIS COPYRIGHT: BIOL ABS. RRM CHINESE HAMSTER BONE MARROW CELLS IN-VIVO MUTAGENICITY GENETIC RISK ADDITIVE COMPOUND EFFECT CARCINOGENICITY,Synergic effects on chromosome aberration frequency of chromium and nickel ions in vivo Abs: BIOSIS COPYRIGHT: BIOL ABS. RRM CHINESE HAMSTER BONE MARROW CELLS IN-VIVO MUTAGENICITY GENETIC RISK ADDITIVE COMPOUND EFFECT CARCINOGENICITY
1237054,Ueno et al. 1988,Effect of chromium on lipid peroxidation in isolated rat hepatocytes,BIOSIS COPYRIGHT: BIOL ABS. RRM THIOBARBITURIC ACID LACTATE DEHYDROGENASE REDUCED GLUTATHIONE ANTIOXIDANTS N N' DIPHENYL-P-PHENYLENEDIAMINE ALPHA TOCOPHEROL CELLULAR INJURY,Effect of chromium on lipid peroxidation in isolated rat hepatocytes Abs: BIOSIS COPYRIGHT: BIOL ABS. RRM THIOBARBITURIC ACID LACTATE DEHYDROGENASE REDUCED GLUTATHIONE ANTIOXIDANTS N N' DIPHENYL-P-PHENYLENEDIAMINE ALPHA TOCOPHEROL CELLULAR INJURY
1237053,Ozawa et al. 1987,EVALUATION OF TOXICITY OF NEPHROTOXIC CHEMICALS IN THE RECONSTRUCTED EPITHELIAL MEMBRANE FORMED BY MDCK CELLS,BIOSIS COPYRIGHT: BIOL ABS. RRM ABSTRACT DOME FORMATION OUABAIN CADMIUM CHLORIDE SODIUM CHROMATE FOLIC ACID GENTAMICIN,EVALUATION OF TOXICITY OF NEPHROTOXIC CHEMICALS IN THE RECONSTRUCTED EPITHELIAL MEMBRANE FORMED BY MDCK CELLS Abs: BIOSIS COPYRIGHT: BIOL ABS. RRM ABSTRACT DOME FORMATION OUABAIN CADMIUM CHLORIDE SODIUM CHROMATE FOLIC ACID GENTAMICIN
1237048,Ruegg et al. 1988,Mercuric chloride and potassium dichromate induced regioselective acute tubular necrosis in renal cortical slices localization and transport studies,BIOSIS COPYRIGHT: BIOL ABS. RRM ABSTRACT,Mercuric chloride and potassium dichromate induced regioselective acute tubular necrosis in renal cortical slices localization and transport studies Abs: BIOSIS COPYRIGHT: BIOL ABS. RRM ABSTRACT
1237044,Ogata et al. 1987,A new microdetermination method used in an analysis of the excretion of trichloro compounds in the urine of workers exposed to trichloroethylene vapor,"BIOSIS COPYRIGHT: BIOL ABS. A method for the microdetermination of trichloro-compounds excreted in the urine of workers exposed to trichloroethylene (TCE) was developed. The glucuronide of trichloroethanol was hydrolyzed enzymatically to trichloroethanol, which was then treated with pyridine and potassium hydroxide. The product was treated with p-chloroaniline. The absorbance of the stable-colored product was read in a spectrophotometer at 500 nm. Trichloroacetic acid (TCA) was assayed similarly by omitting the enzymatic hydrolysis. Absorbance obtained by the present method for TCE or TCA was approximately 3 times as much as that obtained by the alkalipyridine method. The use of toxic and carcinogenic chromium oxide was avoided in the present method. In order to investigate the relationship between the trichloroethylene concentration in the working environments and the metabolite concentrations in the urine, surveys were made at several workshops in automobile parts factories. Urine samples collect","A new microdetermination method used in an analysis of the excretion of trichloro compounds in the urine of workers exposed to trichloroethylene vapor Abs: BIOSIS COPYRIGHT: BIOL ABS. A method for the microdetermination of trichloro-compounds excreted in the urine of workers exposed to trichloroethylene (TCE) was developed. The glucuronide of trichloroethanol was hydrolyzed enzymatically to trichloroethanol, which was then treated with pyridine and potassium hydroxide. The product was treated with p-chloroaniline. The absorbance of the stable-colored product was read in a spectrophotometer at 500 nm. Trichloroacetic acid (TCA) was assayed similarly by omitting the enzymatic hydrolysis. Absorbance obtained by the present method for TCE or TCA was approximately 3 times as much as that obtained by the alkalipyridine method. The use of toxic and carcinogenic chromium oxide was avoided in the present method. In order to investigate the relationship between the trichloroethylene concentration in the working environments and the metabolite concentrations in the urine, surveys were made at several workshops in automobile parts factories. Urine samples collect"
1237041,Friberg et al. 1986,HANDBOOK ON THE TOXICOLOGY OF METALS SECOND EDITION VOL. I. GENERAL ASPECTS,BIOSIS COPYRIGHT: BIOL ABS. RRM BOOK HUMAN ANIMAL,HANDBOOK ON THE TOXICOLOGY OF METALS SECOND EDITION VOL. I. GENERAL ASPECTS Abs: BIOSIS COPYRIGHT: BIOL ABS. RRM BOOK HUMAN ANIMAL
1237039,Olivier and  Marzin 1987,Study of the genotoxic potential of 48 inorganic derivatives with the SOS chromotest,"The genotoxic potential of 48 inorganic derivatives was studied using the bacterial colorimetric assay: the SOS Chromotest. Some of these compounds are known as carcinogens (As, CR(VI), Cd, Ni) or suspected carcinogens for human beings (Hg, Pb), others are known as non-carcinogens. Among these 48 derivatives, only the two Cr(VI) compounds and the Sn(II) compounds gave positive results.","Study of the genotoxic potential of 48 inorganic derivatives with the SOS chromotest Abs: The genotoxic potential of 48 inorganic derivatives was studied using the bacterial colorimetric assay: the SOS Chromotest. Some of these compounds are known as carcinogens (As, CR(VI), Cd, Ni) or suspected carcinogens for human beings (Hg, Pb), others are known as non-carcinogens. Among these 48 derivatives, only the two Cr(VI) compounds and the Sn(II) compounds gave positive results."
1237037,Jop et al. 1987,COMPARATIVE TOXICITY AND SPECIATION OF TWO HEXAVALENT CHROMIUM SALTS IN ACUTE TOXICITY TESTS,BIOSIS COPYRIGHT: BIOL ABS. RRM DAPHNIA-PULEX MYSIDOPSIS-BAHIA CYPRINODON-VARIEGATUS PIMEPHALES-PROMELAS GASTEROSTEUS-ACULEATUS LEPOMIS-MACROCHIRUS ENVIRONMENTAL TOXIN WATER POLLUTION,COMPARATIVE TOXICITY AND SPECIATION OF TWO HEXAVALENT CHROMIUM SALTS IN ACUTE TOXICITY TESTS Abs: BIOSIS COPYRIGHT: BIOL ABS. RRM DAPHNIA-PULEX MYSIDOPSIS-BAHIA CYPRINODON-VARIEGATUS PIMEPHALES-PROMELAS GASTEROSTEUS-ACULEATUS LEPOMIS-MACROCHIRUS ENVIRONMENTAL TOXIN WATER POLLUTION
1237036,Oleru and  Ademiluyi 1987,Some acute and long-term effects of exposure in welding and thermal-cutting operations in Nigeria,"The analysis of welding fumes has shown that toxic gases are present that are irritating to the respiratory system; these gases include nitrogen dioxide and ozone, as well as the oxides of cobalt and chromium The acute and long-term effects of exposure are assessed in the context of a welding and metal plant in Nigeria Evidence of long-term respiratory impairment and potential lung cancer was found.","Some acute and long-term effects of exposure in welding and thermal-cutting operations in Nigeria Abs: The analysis of welding fumes has shown that toxic gases are present that are irritating to the respiratory system; these gases include nitrogen dioxide and ozone, as well as the oxides of cobalt and chromium The acute and long-term effects of exposure are assessed in the context of a welding and metal plant in Nigeria Evidence of long-term respiratory impairment and potential lung cancer was found."
1237031,Guay and  Siemiatycki 1987,HISTORIC COHORT STUDY IN MONTREAL'S FUR INDUSTRY,BIOSIS COPYRIGHT: BIOL ABS. RRM HUMAN WORKERS COLORECTAL CANCER HAZARDOUS MATERIALS HAZARDOUS OCCUPATION OCCUPATIONAL TOXICOLOGY MUTAGEN CARCINOGEN AIR POLLUTION ETHNIC FACTOR CANADA,HISTORIC COHORT STUDY IN MONTREAL'S FUR INDUSTRY Abs: BIOSIS COPYRIGHT: BIOL ABS. RRM HUMAN WORKERS COLORECTAL CANCER HAZARDOUS MATERIALS HAZARDOUS OCCUPATION OCCUPATIONAL TOXICOLOGY MUTAGEN CARCINOGEN AIR POLLUTION ETHNIC FACTOR CANADA
1237028,Yamamoto et al. 1987,ISOLATION OF A BIOLOGICALLY ACTIVE LOW-MOLECULAR-MASS CHROMIUM COMPOUND FROM RABBIT LIVER,BIOSIS COPYRIGHT: BIOL ABS. RRM DETOXIFICATION LIGAND INSULIN GLUCOSE METABOLISM,ISOLATION OF A BIOLOGICALLY ACTIVE LOW-MOLECULAR-MASS CHROMIUM COMPOUND FROM RABBIT LIVER Abs: BIOSIS COPYRIGHT: BIOL ABS. RRM DETOXIFICATION LIGAND INSULIN GLUCOSE METABOLISM
1237027,Miller 1987,AQUATIC MODELS FOR THE STUDY OF RENAL TRANSPORT FUNCTION AND POLLUTANT TOXICITY,BIOSIS COPYRIGHT: BIOL ABS. RRM FLOUNDER CRAB,AQUATIC MODELS FOR THE STUDY OF RENAL TRANSPORT FUNCTION AND POLLUTANT TOXICITY Abs: BIOSIS COPYRIGHT: BIOL ABS. RRM FLOUNDER CRAB
1237026,Steele et al. 1987,EVALUATION OF A RAT TRACHEAL EPITHELIAL CELL CULTURE ASSAY SYSTEM TO DETECT RESPIRATORY CARCINOGENS,BIOSIS COPYRIGHT: BIOL ABS. RRM ABSTRACT N METHYL-N'-NITRO-N-NITROSOGUANIDINE BENZO-A-PYRENE SODIUM CHROMATE BENZ-1-ACEANTHRYLENE FORMALDEHYDE 3 METHYLCHOLANTHRENE,EVALUATION OF A RAT TRACHEAL EPITHELIAL CELL CULTURE ASSAY SYSTEM TO DETECT RESPIRATORY CARCINOGENS Abs: BIOSIS COPYRIGHT: BIOL ABS. RRM ABSTRACT N METHYL-N'-NITRO-N-NITROSOGUANIDINE BENZO-A-PYRENE SODIUM CHROMATE BENZ-1-ACEANTHRYLENE FORMALDEHYDE 3 METHYLCHOLANTHRENE
1237025,Biedermann and  Landolph 1987,CELLULAR UPTAKE AND MUTAGENICITY OF METAL SALTS IN RELATION TO INDUCTION OF ANCHORAGE INDEPENDENCE IN HUMAN FORESKIN FIBROBLASTS,BIOSIS COPYRIGHT: BIOL ABS. RRM ABSTRACT LEAD CHROMATE CALCIUM CHROMATE SODIUM CHROMATE CHROMIC OXIDE CHROMIUM CHLORIDE CARCINOGENS,CELLULAR UPTAKE AND MUTAGENICITY OF METAL SALTS IN RELATION TO INDUCTION OF ANCHORAGE INDEPENDENCE IN HUMAN FORESKIN FIBROBLASTS Abs: BIOSIS COPYRIGHT: BIOL ABS. RRM ABSTRACT LEAD CHROMATE CALCIUM CHROMATE SODIUM CHROMATE CHROMIC OXIDE CHROMIUM CHLORIDE CARCINOGENS
1237024,Kalafatic 1987,EFFECT OF POTASSIUM DICHROMATE UPON REGENERATION OF HYPOSTOME AND FOOT OF HYDRA HYDRA-VULGARIS,BIOSIS COPYRIGHT: BIOL ABS. RRM TOXICITY CARCINOGEN,EFFECT OF POTASSIUM DICHROMATE UPON REGENERATION OF HYPOSTOME AND FOOT OF HYDRA HYDRA-VULGARIS Abs: BIOSIS COPYRIGHT: BIOL ABS. RRM TOXICITY CARCINOGEN
1237023,Vazquez et al. 1987,CHROMIUM-VI INDUCED STRUCTURAL AND ULTRASTRUCTURAL CHANGES IN BUSH BEAN PLANTS PHASEOLUS-VULGARIS L,BIOSIS COPYRIGHT: BIOL ABS. RRM MEMBRANE DAMAGE MINERAL NUTRIENTS OXIDATION ELECTRON MICROSCOPY TOXICITY,CHROMIUM-VI INDUCED STRUCTURAL AND ULTRASTRUCTURAL CHANGES IN BUSH BEAN PLANTS PHASEOLUS-VULGARIS L Abs: BIOSIS COPYRIGHT: BIOL ABS. RRM MEMBRANE DAMAGE MINERAL NUTRIENTS OXIDATION ELECTRON MICROSCOPY TOXICITY
1237021,Ostrow 1987,REACTIVE AIRWAY DYSFUNCTION SYNDROME RADS FREQUENCY AND CLINICAL APPLICABILITY OF DIAGNOSIS,BIOSIS COPYRIGHT: BIOL ABS. RRM ABSTRACT HUMAN WORKER ISOCYANATES PLASTICS ZINC CHROMATE WELDING,REACTIVE AIRWAY DYSFUNCTION SYNDROME RADS FREQUENCY AND CLINICAL APPLICABILITY OF DIAGNOSIS Abs: BIOSIS COPYRIGHT: BIOL ABS. RRM ABSTRACT HUMAN WORKER ISOCYANATES PLASTICS ZINC CHROMATE WELDING
1237017,Costantini et al. 1987,MONITORING OF CARCINOGENIC RISKS IN TANNERY WORKERS BY MEANS OF DESQUAMATIVE LUNG AND BLADDER CYTOLOGY AND URINARY MUTAGENICITY,BIOSIS COPYRIGHT: BIOL ABS. RRM SALMONELLA-TYPHIMURIUM HUMAN ITALY MUTAGEN LUNG CANCER HAZARDOUS MATERIALS HAZARDOUS OCCUPATION OCCUPATIONAL TOXICOLOGY CARCINOGEN LEATHER INDUSTRY CHEMICAL INDUSTRY ENVIRONMENTAL SURVEILLANCE,MONITORING OF CARCINOGENIC RISKS IN TANNERY WORKERS BY MEANS OF DESQUAMATIVE LUNG AND BLADDER CYTOLOGY AND URINARY MUTAGENICITY Abs: BIOSIS COPYRIGHT: BIOL ABS. RRM SALMONELLA-TYPHIMURIUM HUMAN ITALY MUTAGEN LUNG CANCER HAZARDOUS MATERIALS HAZARDOUS OCCUPATION OCCUPATIONAL TOXICOLOGY CARCINOGEN LEATHER INDUSTRY CHEMICAL INDUSTRY ENVIRONMENTAL SURVEILLANCE
1237016,Hamilton and  Wetterhahn 1987,Effect of chromium-induced DNA damage on gene expression in the chick embryo in-vivo,,Effect of chromium-induced DNA damage on gene expression in the chick embryo in-vivo Abs: 
1237015,Francis and  Dodge 1987,DISSOLUTION OF TRANSITION METAL OXIDES BY CLOSTRIDIUM-SP,BIOSIS COPYRIGHT: BIOL ABS. RRM ABSTRACT IRON MANGANESE CADMIUM COPPER LEAD ZINC TOXIC METAL DISPOSAL HAZARD WATERS SOILS,DISSOLUTION OF TRANSITION METAL OXIDES BY CLOSTRIDIUM-SP Abs: BIOSIS COPYRIGHT: BIOL ABS. RRM ABSTRACT IRON MANGANESE CADMIUM COPPER LEAD ZINC TOXIC METAL DISPOSAL HAZARD WATERS SOILS
1237014,Storer 1986,1986 ANNUAL BOOK OF ASTM AMERICAN SOCIETY OF TESTING AND MATERIALS STANDARDS SECTION 11. WATER AND ENVIRONMENTAL TECHNOLOGY VOL. 11.03. ATMOSPHERIC ANALYSIS OCCUPATIONAL HEALTH AND SAFETY,BIOSIS COPYRIGHT: BIOL ABS. RRM BOOK HUMAN WORKER CARBON DISULFIDE ASBESTOS HYDROCARBONS FLUORIDE LEAD CHROMATE SULFUR DIOXIDE OZONE AIR POLLUTION MONITORING,1986 ANNUAL BOOK OF ASTM AMERICAN SOCIETY OF TESTING AND MATERIALS STANDARDS SECTION 11. WATER AND ENVIRONMENTAL TECHNOLOGY VOL. 11.03. ATMOSPHERIC ANALYSIS OCCUPATIONAL HEALTH AND SAFETY Abs: BIOSIS COPYRIGHT: BIOL ABS. RRM BOOK HUMAN WORKER CARBON DISULFIDE ASBESTOS HYDROCARBONS FLUORIDE LEAD CHROMATE SULFUR DIOXIDE OZONE AIR POLLUTION MONITORING
1237012,Fisher 1987,P-TERT BUTYLPHENOL FORMALDEHYDE RESIN PART I. LEATHER WATCH STRAPS AND SHOES,BIOSIS COPYRIGHT: BIOL ABS. RRM HUMAN POTASSIUM DICHROMATE CONTACT DERMATITIS,P-TERT BUTYLPHENOL FORMALDEHYDE RESIN PART I. LEATHER WATCH STRAPS AND SHOES Abs: BIOSIS COPYRIGHT: BIOL ABS. RRM HUMAN POTASSIUM DICHROMATE CONTACT DERMATITIS
1237007,Sokolov 1986,METHODOLOGICAL ASPECTS OF ASSESSING ATMOSPHERIC CONTAMINATION WITH METAL AEROSOLS IN THE VICINITY OF THERMAL POWER COMPLEXES,BIOSIS COPYRIGHT: BIOL ABS. RRM VANADIUM-V OXIDE ALUMINUM-III OXIDE NICKEL-III OXIDE IRON-III OXIDE MANGANESE-II OXIDE CHROMIUM-III OXIDE OIL FUEL,METHODOLOGICAL ASPECTS OF ASSESSING ATMOSPHERIC CONTAMINATION WITH METAL AEROSOLS IN THE VICINITY OF THERMAL POWER COMPLEXES Abs: BIOSIS COPYRIGHT: BIOL ABS. RRM VANADIUM-V OXIDE ALUMINUM-III OXIDE NICKEL-III OXIDE IRON-III OXIDE MANGANESE-II OXIDE CHROMIUM-III OXIDE OIL FUEL
1237001,Nesnow et al. 1987,CHEMICAL CARCINOGENS A REVIEW AND ANALYSIS OF THE LITERATURE OF SELECTED CHEMICALS AND THE ESTABLISHMENT OF THE GENE-TOX CARCINOGEN DATA BASE,BIOSIS COPYRIGHT: BIOL ABS. RRM EPA,CHEMICAL CARCINOGENS A REVIEW AND ANALYSIS OF THE LITERATURE OF SELECTED CHEMICALS AND THE ESTABLISHMENT OF THE GENE-TOX CARCINOGEN DATA BASE Abs: BIOSIS COPYRIGHT: BIOL ABS. RRM EPA
1236996,Goh 1986,CONTACT SENSITIVITY IN SINGAPORE,BIOSIS COPYRIGHT: BIOL ABS. RRM HUMAN PROFLAVINE NICKEL FRAGRANCE MIX POTASSIUM DICHROMATE NEOMYCIN VIOFORM OCCUPATIONAL CONTACT DERMATITIS PATCH TEST,CONTACT SENSITIVITY IN SINGAPORE Abs: BIOSIS COPYRIGHT: BIOL ABS. RRM HUMAN PROFLAVINE NICKEL FRAGRANCE MIX POTASSIUM DICHROMATE NEOMYCIN VIOFORM OCCUPATIONAL CONTACT DERMATITIS PATCH TEST
1236995,Menne 1986,STANDARD TEST SERIES IN EUROPE,BIOSIS COPYRIGHT: BIOL ABS. RRM HUMAN NEOMYCIN NICKEL CHROMATE RUBBER CHEMICALS FRAGRANCE MIXTURES COLOPHONY CONTACT DERMATITIS STANDARD TRAY PATCH TEST,STANDARD TEST SERIES IN EUROPE Abs: BIOSIS COPYRIGHT: BIOL ABS. RRM HUMAN NEOMYCIN NICKEL CHROMATE RUBBER CHEMICALS FRAGRANCE MIXTURES COLOPHONY CONTACT DERMATITIS STANDARD TRAY PATCH TEST
1236991,Sertoli et al. 1986,COMPUTER ANALYSIS OF 3312 CASES OF CONTACT DERMATITIS,BIOSIS COPYRIGHT: BIOL ABS. RRM HUMAN WORKERS HOUSEWIFE CONSTRUCTION WORKER HEALTH CARE WORKER HAIRDRESSER STEEL WORKER SEX DIFFERENCE CLOTHING PERFUME DRUG TOXICITY POTASSIUM BICHROMATE NICKEL SULFATE METALS BALSAM OF PERU COBALT OCCUPATIONAL TOXICOLOGY HAZARDOUS MATERIALS HAZARDOUS OCCUPATION CONSTRUCTION INDUSTRY METAL INDUSTRY HEALTH CARE INDUSTRY,COMPUTER ANALYSIS OF 3312 CASES OF CONTACT DERMATITIS Abs: BIOSIS COPYRIGHT: BIOL ABS. RRM HUMAN WORKERS HOUSEWIFE CONSTRUCTION WORKER HEALTH CARE WORKER HAIRDRESSER STEEL WORKER SEX DIFFERENCE CLOTHING PERFUME DRUG TOXICITY POTASSIUM BICHROMATE NICKEL SULFATE METALS BALSAM OF PERU COBALT OCCUPATIONAL TOXICOLOGY HAZARDOUS MATERIALS HAZARDOUS OCCUPATION CONSTRUCTION INDUSTRY METAL INDUSTRY HEALTH CARE INDUSTRY
1236990,Sutou 1986,SEX DIFFERENCE IN THE MICRONUCLEUS TEST THE COLLABORATIVE STUDY GROUP FOR THE MICRONUCLEUS TEST,BIOSIS COPYRIGHT: BIOL ABS. RRM MOUSE CLASTOGEN MUTAGEN 2 ACETYLAMINOFLUORENE BENZENE BENZO-A-PYRENE 7 12 DIMETHYLBENZANTHRACENE ETHYL METHANESULFONATE,SEX DIFFERENCE IN THE MICRONUCLEUS TEST THE COLLABORATIVE STUDY GROUP FOR THE MICRONUCLEUS TEST Abs: BIOSIS COPYRIGHT: BIOL ABS. RRM MOUSE CLASTOGEN MUTAGEN 2 ACETYLAMINOFLUORENE BENZENE BENZO-A-PYRENE 7 12 DIMETHYLBENZANTHRACENE ETHYL METHANESULFONATE
1236989,Gawkrodger et al. 1986,OCCUPATIONAL SKIN DISEASE IN HOSPITAL CLEANING AND KITCHEN WORKERS,BIOSIS COPYRIGHT: BIOL ABS. RRM HUMAN NICKEL METALS JEWELERY DERMATITIS HAND DERMATITIS PSORIASIS WET WORK WORK ENVIRONMENT OCCUPATIONAL TOXICOLOGY HAZARDOUS MATERIALS HAZARDOUS OCCUPATION HEALTH CARE INDUSTRY,OCCUPATIONAL SKIN DISEASE IN HOSPITAL CLEANING AND KITCHEN WORKERS Abs: BIOSIS COPYRIGHT: BIOL ABS. RRM HUMAN NICKEL METALS JEWELERY DERMATITIS HAND DERMATITIS PSORIASIS WET WORK WORK ENVIRONMENT OCCUPATIONAL TOXICOLOGY HAZARDOUS MATERIALS HAZARDOUS OCCUPATION HEALTH CARE INDUSTRY
1236985,Hofnung and  Quillardet 1986,RECENT DEVELOPMENTS IN BACTERIAL SHORT-TERM TESTS FOR THE DETECTION OF GENOTOXIC AGENTS,BIOSIS COPYRIGHT: BIOL ABS. RRM REVIEW SALMONELLA ESCHERICHIA-COLI DNA MUTAGENESIS,RECENT DEVELOPMENTS IN BACTERIAL SHORT-TERM TESTS FOR THE DETECTION OF GENOTOXIC AGENTS Abs: BIOSIS COPYRIGHT: BIOL ABS. RRM REVIEW SALMONELLA ESCHERICHIA-COLI DNA MUTAGENESIS
1236984,Thomas et al. 1986,BODY SPLINT DERMATITIS IN CHILDHOOD,BIOSIS COPYRIGHT: BIOL ABS. RRM ECZEMA PERSPIRATION LEATHER POTASSIUM DICHROMATE,BODY SPLINT DERMATITIS IN CHILDHOOD Abs: BIOSIS COPYRIGHT: BIOL ABS. RRM ECZEMA PERSPIRATION LEATHER POTASSIUM DICHROMATE
1236983,Requena et al. 1986,EPOXY DERMATITIS OF AN AMPUTATION STUMP,BIOSIS COPYRIGHT: BIOL ABS. RRM HUMAN WOODEN PROSTHESIS VARNISH,EPOXY DERMATITIS OF AN AMPUTATION STUMP Abs: BIOSIS COPYRIGHT: BIOL ABS. RRM HUMAN WOODEN PROSTHESIS VARNISH
1236979,Anestis and  Neufeld 1986,AVOIDANCE-PREFERENCE REACTIONS OF RAINBOW TROUT SALMO-GAIRDNERI AFTER PROLONGED EXPOSURE TO CHROMIUM-VI,BIOSIS COPYRIGHT: BIOL ABS. RRM POTASSIUM DICHROMATE METAL POLLUTION,AVOIDANCE-PREFERENCE REACTIONS OF RAINBOW TROUT SALMO-GAIRDNERI AFTER PROLONGED EXPOSURE TO CHROMIUM-VI Abs: BIOSIS COPYRIGHT: BIOL ABS. RRM POTASSIUM DICHROMATE METAL POLLUTION
1236975,Sugiyama and  Costa 1986,Characterization of DNA damage induced by calcium chromate in cultured mammalian cells,BIOSIS COPYRIGHT: BIOL ABS. RRM ABSTRACT CHINESE HAMSTER CELL PROTEIN MUTAGENESIS,Characterization of DNA damage induced by calcium chromate in cultured mammalian cells Abs: BIOSIS COPYRIGHT: BIOL ABS. RRM ABSTRACT CHINESE HAMSTER CELL PROTEIN MUTAGENESIS
1236973,Nakamuro and  Sayato 1986,FORMS OF CHROMIUM IN RAT BLOOD TREATED IN-VIVO AND IN-VITRO WITH CHROMIUM-51 SODIUM CHROMATE AND CHROMIUM-51 CHROMIUM-II CHLORIDE,BIOSIS COPYRIGHT: BIOL ABS. RRM HEMOGLOBIN ENVIRONMENTAL POLLUTION,FORMS OF CHROMIUM IN RAT BLOOD TREATED IN-VIVO AND IN-VITRO WITH CHROMIUM-51 SODIUM CHROMATE AND CHROMIUM-51 CHROMIUM-II CHLORIDE Abs: BIOSIS COPYRIGHT: BIOL ABS. RRM HEMOGLOBIN ENVIRONMENTAL POLLUTION
1236966,Biedermann and  Landolph 1986,INDUCTION OF ANCHORAGE INDEPENDENCE IN HUMAN DIPLOID FORESKIN FIBROBLASTS BY METAL SALTS,BIOSIS COPYRIGHT: BIOL ABS. RRM ABSTRACT N METHYL-N'-NITRO-N-NITROSOGUANIDINE,INDUCTION OF ANCHORAGE INDEPENDENCE IN HUMAN DIPLOID FORESKIN FIBROBLASTS BY METAL SALTS Abs: BIOSIS COPYRIGHT: BIOL ABS. RRM ABSTRACT N METHYL-N'-NITRO-N-NITROSOGUANIDINE
1236960,Hiwasa and  Sakiyama 1986,INCREASE IN THE SYNTHESIS OF A 32000-MOLECULAR-WEIGHT PROTEIN IN BALB-C-3T3 CELLS AFTER TREATMENT WITH TUMOR PROMOTERS CHEMICAL CARCINOGENS METAL SALTS AND HEAT SHOCK,BIOSIS COPYRIGHT: BIOL ABS. RRM MOUSE FIBROBLASTS METHYL METHANESULFONATE N METHYL-N'-NITRO-N-NITROSOGUANIDINE L ASCORBIC-ACID SODIUM DEOXYCHOLATE P TOSYL-L-PHENYLALANINE CHLOROMETHYL KETONE P TOSYL-L-LYSINE CHLOROMETHYL KETONE 3 3' DIAMINOBENZIDINE SELENIUM GENE EXPRESSION,INCREASE IN THE SYNTHESIS OF A 32000-MOLECULAR-WEIGHT PROTEIN IN BALB-C-3T3 CELLS AFTER TREATMENT WITH TUMOR PROMOTERS CHEMICAL CARCINOGENS METAL SALTS AND HEAT SHOCK Abs: BIOSIS COPYRIGHT: BIOL ABS. RRM MOUSE FIBROBLASTS METHYL METHANESULFONATE N METHYL-N'-NITRO-N-NITROSOGUANIDINE L ASCORBIC-ACID SODIUM DEOXYCHOLATE P TOSYL-L-PHENYLALANINE CHLOROMETHYL KETONE P TOSYL-L-LYSINE CHLOROMETHYL KETONE 3 3' DIAMINOBENZIDINE SELENIUM GENE EXPRESSION
1236947,Murkami 1985,MICROSTRUCTURE OF SYNROC,BIOSIS COPYRIGHT: BIOL ABS. RRM PEROVSKITE HOLLANDITE ZIRCONOLITE MAGNETOPLUMBITE TRANSMISSION ELECTRON MICROSCOPY RADIOACTIVE WASTE DISPOSAL MOLYBDENUM CESIUM SODIUM,MICROSTRUCTURE OF SYNROC Abs: BIOSIS COPYRIGHT: BIOL ABS. RRM PEROVSKITE HOLLANDITE ZIRCONOLITE MAGNETOPLUMBITE TRANSMISSION ELECTRON MICROSCOPY RADIOACTIVE WASTE DISPOSAL MOLYBDENUM CESIUM SODIUM
1236946,Hatch et al. 1985,CHEMICAL ENHANCEMENT OF SA-7 VIRUS TRANSFORMATION OF HAMSTER EMBRYO CELLS INTERLABORATORY TESTING OF DIVERSE CHEMICALS,BIOSIS COPYRIGHT: BIOL ABS. RRM RESERPINE DIETHYLNITROSAMINE N METHYL-N'-NITRO-N-NITROSOGUANIDINE LEAD CHROMATE 2 ACETYLAMINOFLUORENE ANTHRACENE BENZO-A-PYRENE 7 12 DIMETHYLBENZANTHRACENE PYRENE 4 NITROQUINOLINE-N-OXIDE DICHLORVOS CINNAMYL ANTHRANILATE 4 4' OXYDIANILINE 2 6 DICHLORO-P-PHENYLENEDIAMINE CARCINOGEN,CHEMICAL ENHANCEMENT OF SA-7 VIRUS TRANSFORMATION OF HAMSTER EMBRYO CELLS INTERLABORATORY TESTING OF DIVERSE CHEMICALS Abs: BIOSIS COPYRIGHT: BIOL ABS. RRM RESERPINE DIETHYLNITROSAMINE N METHYL-N'-NITRO-N-NITROSOGUANIDINE LEAD CHROMATE 2 ACETYLAMINOFLUORENE ANTHRACENE BENZO-A-PYRENE 7 12 DIMETHYLBENZANTHRACENE PYRENE 4 NITROQUINOLINE-N-OXIDE DICHLORVOS CINNAMYL ANTHRANILATE 4 4' OXYDIANILINE 2 6 DICHLORO-P-PHENYLENEDIAMINE CARCINOGEN
1236945,Tennant et al. 1985,COMPARATIVE EVALUATION OF THREE MAMMALIAN CELL TRANSFORMATION ASSAY SYSTEMS,BIOSIS COPYRIGHT: BIOL ABS. RRM SYRIAN HAMSTER EMBRYO CELLS RAT FIBROBLAST CELL LINE 2-FR-450 SIMIAN ADENOVIRUS TYPE 7 RAUSCHER LEUKEMIA VIRUS ONCORNAVIRUS LEAD CHROMATE ANTHRACENE PYRENE N ACETYLAMINOFLUORENE BENZO-A-PYRENE DIETHYLNITROSAMINE 7 12 DIMETHYLBENZANTHRACENE 4 NITROQUINOLINE-N-OXIDE N METHYL-N'-NITRO-N-NITROSOGUANIDINE CARCINOGEN,COMPARATIVE EVALUATION OF THREE MAMMALIAN CELL TRANSFORMATION ASSAY SYSTEMS Abs: BIOSIS COPYRIGHT: BIOL ABS. RRM SYRIAN HAMSTER EMBRYO CELLS RAT FIBROBLAST CELL LINE 2-FR-450 SIMIAN ADENOVIRUS TYPE 7 RAUSCHER LEUKEMIA VIRUS ONCORNAVIRUS LEAD CHROMATE ANTHRACENE PYRENE N ACETYLAMINOFLUORENE BENZO-A-PYRENE DIETHYLNITROSAMINE 7 12 DIMETHYLBENZANTHRACENE 4 NITROQUINOLINE-N-OXIDE N METHYL-N'-NITRO-N-NITROSOGUANIDINE CARCINOGEN
1236944,Styles and  Penman 1985,THE MOUSE SPOT TEST EVALUATION OF ITS PERFORMANCE IN IDENTIFYING CHEMICAL MUTAGENS AND CARCINOGENS,BIOSIS COPYRIGHT: BIOL ABS. RRM X-RAY,THE MOUSE SPOT TEST EVALUATION OF ITS PERFORMANCE IN IDENTIFYING CHEMICAL MUTAGENS AND CARCINOGENS Abs: BIOSIS COPYRIGHT: BIOL ABS. RRM X-RAY
1236936,Litvinov 1985,HYGIENIC CLASSIFICATION OF CARCINOGENIC SUBSTANCES AND THE POSSIBILITY OF USING IT IN PREVENTION OF CARCINOGENIC EFFECTS,BIOSIS COPYRIGHT: BIOL ABS. RRM HUMAN POLLUTION,HYGIENIC CLASSIFICATION OF CARCINOGENIC SUBSTANCES AND THE POSSIBILITY OF USING IT IN PREVENTION OF CARCINOGENIC EFFECTS Abs: BIOSIS COPYRIGHT: BIOL ABS. RRM HUMAN POLLUTION
1236935,Sweeney et al. 1985,Mortality among retired fur workers dyers dressers tanners and service workers,"A retrospective cohort mortality study was conducted on 807 fur dyers, fur dressers (tanners), and fur service workers who were pensioned between 1952 and 1977 by the Fur, Leather and Machine Workers Union of New York City. Workplace exposures of fur workers varied with job category. Dyers were exposed to oxidative dyes used in commercial hair dyes; dressers and service workers were exposed to tanning chemicals. In a comparison with the New York City population, no significant increases in mortality were observed among the fur dyers. Among fur dressers, mortality from all malignant neoplasms [standardized mortality ratio (SMR) 151] and lung cancer (SMR 232) was significantly elevated, as was mortality from cardiovascular disease (SMR 126) among fur service workers. When examined by ethnic origin, the elevated SMR values and directly age-adjusted rate ratios suggested that foreign-born fur dressers and eastern European-born fur workers experienced the highest risks for lung and colorectal cancers, respectively. These data support previous findings of increased mortality from colorectal cancer in the foreign-born population of the United States and suggest a possible occupational etiology for the observed lung cancer excess.","Mortality among retired fur workers dyers dressers tanners and service workers Abs: A retrospective cohort mortality study was conducted on 807 fur dyers, fur dressers (tanners), and fur service workers who were pensioned between 1952 and 1977 by the Fur, Leather and Machine Workers Union of New York City. Workplace exposures of fur workers varied with job category. Dyers were exposed to oxidative dyes used in commercial hair dyes; dressers and service workers were exposed to tanning chemicals. In a comparison with the New York City population, no significant increases in mortality were observed among the fur dyers. Among fur dressers, mortality from all malignant neoplasms [standardized mortality ratio (SMR) 151] and lung cancer (SMR 232) was significantly elevated, as was mortality from cardiovascular disease (SMR 126) among fur service workers. When examined by ethnic origin, the elevated SMR values and directly age-adjusted rate ratios suggested that foreign-born fur dressers and eastern European-born fur workers experienced the highest risks for lung and colorectal cancers, respectively. These data support previous findings of increased mortality from colorectal cancer in the foreign-born population of the United States and suggest a possible occupational etiology for the observed lung cancer excess."
1236932,Knox et al. 1986,ACQUIRED PERFORATING DISEASE IN OIL FIELD WORKERS,BIOSIS COPYRIGHT: BIOL ABS. RRM HUMAN MOUSE DRILLING FLUID CALCIUM,ACQUIRED PERFORATING DISEASE IN OIL FIELD WORKERS Abs: BIOSIS COPYRIGHT: BIOL ABS. RRM HUMAN MOUSE DRILLING FLUID CALCIUM
1236930,Elias et al. 1986,"Cellular uptake, cytotoxic and mutagenic effects of insoluble chromic oxide in V79 Chinese hamster cells","The cellular uptake, the cytotoxicity and the induction of resistance to 6-thioguanine (6-TG) in Chinese hamster V79 cells exposed to insoluble crystalline trivalent chromium (Cr(III)), Cr2O3, were investigated. Intracytoplasmic Cr2O3 crystalline particle-containing vacuoles were observed by electron microscopy. Concentrations of 50-200 mug/ml did not have a marked killing effect but did show a predominantly concentration-dependent inhibitory effect on cell cycle progression with accumulation of cells in G2 phase. Exposure for 18 h to Cr2O3 induced a statistically significant (p 0.001) increase in the mutation frequency of up to 10-fold over the controls. Expression time was 6 days for the lowest concentration and 9 days for the highest. Culture of 6-TGr clones in selective media indicated that they were mutants at the hypoxanthine-guanine phosphoribosyl transferase (HGPRT) locus. Examination of growth patterns of Cr2O3-induced mutants showed that, after a delay in","Cellular uptake, cytotoxic and mutagenic effects of insoluble chromic oxide in V79 Chinese hamster cells Abs: The cellular uptake, the cytotoxicity and the induction of resistance to 6-thioguanine (6-TG) in Chinese hamster V79 cells exposed to insoluble crystalline trivalent chromium (Cr(III)), Cr2O3, were investigated. Intracytoplasmic Cr2O3 crystalline particle-containing vacuoles were observed by electron microscopy. Concentrations of 50-200 mug/ml did not have a marked killing effect but did show a predominantly concentration-dependent inhibitory effect on cell cycle progression with accumulation of cells in G2 phase. Exposure for 18 h to Cr2O3 induced a statistically significant (p 0.001) increase in the mutation frequency of up to 10-fold over the controls. Expression time was 6 days for the lowest concentration and 9 days for the highest. Culture of 6-TGr clones in selective media indicated that they were mutants at the hypoxanthine-guanine phosphoribosyl transferase (HGPRT) locus. Examination of growth patterns of Cr2O3-induced mutants showed that, after a delay in"
1236928,Skaug et al. 1985,IN-VITRO CYTOTOXICITY OF FIBROUS AND NON-FIBROUS LEAD CHROMATE PARTICLES IN HUMAN BRONCHIAL EPITHELIAL CELLS AND RAT ALVEOLAR MACROPHAGES,BIOSIS COPYRIGHT: BIOL ABS. RRM WORKROOM AIR MUTAGEN CARCINOGEN,IN-VITRO CYTOTOXICITY OF FIBROUS AND NON-FIBROUS LEAD CHROMATE PARTICLES IN HUMAN BRONCHIAL EPITHELIAL CELLS AND RAT ALVEOLAR MACROPHAGES Abs: BIOSIS COPYRIGHT: BIOL ABS. RRM WORKROOM AIR MUTAGEN CARCINOGEN
1236925,Babich et al. 1985,THE MEDIATION OF MUTAGENICITY AND CLASTOGENICITY OF HEAVY METALS BY PHYSICOCHEMICAL FACTORS,BIOSIS COPYRIGHT: BIOL ABS. RRM REVIEW TERATOGEN CARCINOGEN METAL POLLUTION,THE MEDIATION OF MUTAGENICITY AND CLASTOGENICITY OF HEAVY METALS BY PHYSICOCHEMICAL FACTORS Abs: BIOSIS COPYRIGHT: BIOL ABS. RRM REVIEW TERATOGEN CARCINOGEN METAL POLLUTION
1236924,Mitoma 1985,TESTS FOR RENAL FUNCTION,BIOSIS COPYRIGHT: BIOL ABS. RRM RAT DOG RABBIT CELLURIA NEPHROTOXICITY RENAL ENZYME CREATININE BLOOD UREA NITROGEN,TESTS FOR RENAL FUNCTION Abs: BIOSIS COPYRIGHT: BIOL ABS. RRM RAT DOG RABBIT CELLURIA NEPHROTOXICITY RENAL ENZYME CREATININE BLOOD UREA NITROGEN
1236908,Larrain et al. 1999,Toxicity of metals and pesticides using the sperm cell bioassay with the sea urchin Arbacia spatuligera,BIOSIS COPYRIGHT: BIOL ABS. RRM RESEARCH ARTICLE ARBACIA SPATULIGERA SPERM CELL BIOASSAY TOXICOLOGY BIOCHEMISTRY AND BIOPHYSICS COPPER HEAVY METAL TOXIN CHROMIUM CADMIUM ZINC PENTACHLOROPHENOL PESTICIDE 2 4-D BIOASSAY METHOD,Toxicity of metals and pesticides using the sperm cell bioassay with the sea urchin Arbacia spatuligera Abs: BIOSIS COPYRIGHT: BIOL ABS. RRM RESEARCH ARTICLE ARBACIA SPATULIGERA SPERM CELL BIOASSAY TOXICOLOGY BIOCHEMISTRY AND BIOPHYSICS COPPER HEAVY METAL TOXIN CHROMIUM CADMIUM ZINC PENTACHLOROPHENOL PESTICIDE 2 4-D BIOASSAY METHOD
1236905,Strati et al. 1999,Root length and distribution of chromium in Corylus avellana with Tuber albidum mycorrhizas,"BIOSIS COPYRIGHT: BIOL ABS. Non-mycorrhizal Corylus avellana L. seedlings and filbert seedlings colonized with Tuber albidum Pico were grown in semihydroponic culture with frequent renewed nutrient solution. The seedlings were exposed to 0.96 muM of KCr(SO4)2 12H2O and of K2CrO4 for one month. Such a low concentration of Cr slightly increased the fine root length. Chromium did not vary the degree of infection with T. albidum, while reduced the colonization with alien fungi. Chromium accumulated in the roots both in mycorrh","Root length and distribution of chromium in Corylus avellana with Tuber albidum mycorrhizas Abs: BIOSIS COPYRIGHT: BIOL ABS. Non-mycorrhizal Corylus avellana L. seedlings and filbert seedlings colonized with Tuber albidum Pico were grown in semihydroponic culture with frequent renewed nutrient solution. The seedlings were exposed to 0.96 muM of KCr(SO4)2 12H2O and of K2CrO4 for one month. Such a low concentration of Cr slightly increased the fine root length. Chromium did not vary the degree of infection with T. albidum, while reduced the colonization with alien fungi. Chromium accumulated in the roots both in mycorrh"
1236902,Gunaydin et al. 1999,The removal of Cr(VI) from aqueous solutions using zinc extraction residue,"BIOSIS COPYRIGHT: BIOL ABS. This study deals with the removal of Cr(VI) from aqueous solutions by using filter cake known as zinc extraction residue (ZER) generated as a by product in a zinc production plant located in Kayseri-TURKEY. It was found that ZER, which is rich in lead compounds, has a great affinity for chromate ions. The Cr(VI) removal yield decreased with increasing initial concentration of Cr(VI) solution. An increase in the dosage of ZER caused an increase in the removal yield and the concentration of Pb, Cd her than those mentioned above. Minimum removal (26.5 %) was observed at initial pH value of 3.05. XRD analysis showed that low-solubility lead chromates were formed in the removal process.","The removal of Cr(VI) from aqueous solutions using zinc extraction residue Abs: BIOSIS COPYRIGHT: BIOL ABS. This study deals with the removal of Cr(VI) from aqueous solutions by using filter cake known as zinc extraction residue (ZER) generated as a by product in a zinc production plant located in Kayseri-TURKEY. It was found that ZER, which is rich in lead compounds, has a great affinity for chromate ions. The Cr(VI) removal yield decreased with increasing initial concentration of Cr(VI) solution. An increase in the dosage of ZER caused an increase in the removal yield and the concentration of Pb, Cd her than those mentioned above. Minimum removal (26.5 %) was observed at initial pH value of 3.05. XRD analysis showed that low-solubility lead chromates were formed in the removal process."
1236899,Zoll-Moreux and  Ferrier 1999,The Jaylet test (newt micronucleus test) and the micronucleus test in xenopus: Two in vivo tests on amphibia evaluation of the genotoxicity of five environmental pollutants and of five effluents,"BIOSIS COPYRIGHT: BIOL ABS. The sensitivity and the reliability of two in vivo genotoxicity tests were compared: the Jaylet test (or the newt micronucleus test) and the micronucleus test in xenopus. The Jaylet test is now a French standard method for testing genotoxicity in water, whereas the micronucleus test in xenopus was set up much more recently. Xenopus does, however, have certain practical advantages over the pleurodele. The study involved two phases, in the first we assessed the ability to detect the genotoxicity o ces was positive with the Jaylet test but not with the micronucleus test in xenopus (pyrene). Onesubstance (bis(-tributyltin)oxide) gave negative results in both micronucleus tests. Only two of the five wastewaters were genotoxic with the Jaylet test: wastewater from a built-up area and effluent from a cokery. The effluent from a chemical plant was positive prior to the treatment stage. These two effluents give a positive response with the micronucleus test in xenopus. Wastewater","The Jaylet test (newt micronucleus test) and the micronucleus test in xenopus: Two in vivo tests on amphibia evaluation of the genotoxicity of five environmental pollutants and of five effluents Abs: BIOSIS COPYRIGHT: BIOL ABS. The sensitivity and the reliability of two in vivo genotoxicity tests were compared: the Jaylet test (or the newt micronucleus test) and the micronucleus test in xenopus. The Jaylet test is now a French standard method for testing genotoxicity in water, whereas the micronucleus test in xenopus was set up much more recently. Xenopus does, however, have certain practical advantages over the pleurodele. The study involved two phases, in the first we assessed the ability to detect the genotoxicity o ces was positive with the Jaylet test but not with the micronucleus test in xenopus (pyrene). Onesubstance (bis(-tributyltin)oxide) gave negative results in both micronucleus tests. Only two of the five wastewaters were genotoxic with the Jaylet test: wastewater from a built-up area and effluent from a cokery. The effluent from a chemical plant was positive prior to the treatment stage. These two effluents give a positive response with the micronucleus test in xenopus. Wastewater"
1236898,Kusk and  Wollenberger 1999,Fully defined saltwater medium for cultivation of and toxicity testing with marine copepod Acartia tonsa,"BIOSIS COPYRIGHT: BIOL ABS. The marine copepod Acartia tonsa and the food organism Rhodomonas salina were cultured in fully defined medium for 8 months without problems. Both organisms were also cultured in natural seawater and in a commercial salt mixture for at least two generations before the sensitivities of A. tonsa to bisphenol A, potassium dichromate, nonylphenol, and 3,5-dichlorophenol in the three different media were compared and found to be at the same level. The defined medium may be used for cultivation and te","Fully defined saltwater medium for cultivation of and toxicity testing with marine copepod Acartia tonsa Abs: BIOSIS COPYRIGHT: BIOL ABS. The marine copepod Acartia tonsa and the food organism Rhodomonas salina were cultured in fully defined medium for 8 months without problems. Both organisms were also cultured in natural seawater and in a commercial salt mixture for at least two generations before the sensitivities of A. tonsa to bisphenol A, potassium dichromate, nonylphenol, and 3,5-dichlorophenol in the three different media were compared and found to be at the same level. The defined medium may be used for cultivation and te"
1236897,Jensen and  Christensen 1999,Colloidal and dissolved metals in leachates from four Danish landfills,"BIOSIS COPYRIGHT: BIOL ABS. Landfill leachate samples were collected at four Danish landfills. The samples were collected anaerobically for characterization of the leachate in terms of pH, total alkalinity, total solids, total organic carbon, cations, anions and heavy metals. The sample procedure was designed to accurately reflect the in situ mobile colloid and associated contaminant concentrations. The leachate samples were separated into size fractions in order to obtain information about size distribution of colloids an ) with total organic carbon (TOC) as one of the major components of the colloidal mass. Also Si, Al, Ca, Fe and S were found in the colloidal fractions. This indicated that both clay type particles, organic matter and precipitates (most likely sulfides) were present in the leachate samples. The distribution of the investigated elements varied from Cl being primarily in the dissolved fraction to Fe which mostly was found in the colloidal fractions. The concentrations of heavy meta","Colloidal and dissolved metals in leachates from four Danish landfills Abs: BIOSIS COPYRIGHT: BIOL ABS. Landfill leachate samples were collected at four Danish landfills. The samples were collected anaerobically for characterization of the leachate in terms of pH, total alkalinity, total solids, total organic carbon, cations, anions and heavy metals. The sample procedure was designed to accurately reflect the in situ mobile colloid and associated contaminant concentrations. The leachate samples were separated into size fractions in order to obtain information about size distribution of colloids an ) with total organic carbon (TOC) as one of the major components of the colloidal mass. Also Si, Al, Ca, Fe and S were found in the colloidal fractions. This indicated that both clay type particles, organic matter and precipitates (most likely sulfides) were present in the leachate samples. The distribution of the investigated elements varied from Cl being primarily in the dissolved fraction to Fe which mostly was found in the colloidal fractions. The concentrations of heavy meta"
1236895,Verschaeve et al. 1999,VITOTOX bacterial genotoxicity and toxicity test for the rapid screening of chemicals,BIOSIS COPYRIGHT: BIOL ABS. The VITOTOX test is a new bacterial genotoxicity test that was previously shown to be very rapid and sensitive. Initially only one Salmonella typhimurium strain (TA104 recN2-4) was used in the test. In this paper we introduce a second strain (TA104pr1) that can be used as an internal control to further enhance the reliability of the test. We demonstrate the usefulness of this pr1 strain in genotoxicity and toxicity testing. We also report on the results of a study where the VITOTOX test was pe,VITOTOX bacterial genotoxicity and toxicity test for the rapid screening of chemicals Abs: BIOSIS COPYRIGHT: BIOL ABS. The VITOTOX test is a new bacterial genotoxicity test that was previously shown to be very rapid and sensitive. Initially only one Salmonella typhimurium strain (TA104 recN2-4) was used in the test. In this paper we introduce a second strain (TA104pr1) that can be used as an internal control to further enhance the reliability of the test. We demonstrate the usefulness of this pr1 strain in genotoxicity and toxicity testing. We also report on the results of a study where the VITOTOX test was pe
1236894,Stinco et al. 1999,Frequency of delayed-type hypersensitivity to contact allergens in psoriatic patients,BIOSIS COPYRIGHT: BIOL ABS. RRM RESEARCH ARTICLE HUMAN HUMAN PATIENT PSORIASIS DELAYED-TYPE HYPERSENSITIVITY DERMATOLOGY ALLERGY PSORIASIS AREA SEVERITY INDEX SCALE CONTACT ALLERGENS INTEGUMENTARY SYSTEM DISEASE IMMUNE SYSTEM DISEASE,Frequency of delayed-type hypersensitivity to contact allergens in psoriatic patients Abs: BIOSIS COPYRIGHT: BIOL ABS. RRM RESEARCH ARTICLE HUMAN HUMAN PATIENT PSORIASIS DELAYED-TYPE HYPERSENSITIVITY DERMATOLOGY ALLERGY PSORIASIS AREA SEVERITY INDEX SCALE CONTACT ALLERGENS INTEGUMENTARY SYSTEM DISEASE IMMUNE SYSTEM DISEASE
1236893,Rettberg et al. 1999,Microscale application of the SOS-LUX-TEST as biosensor for genotoxic agents,BIOSIS COPYRIGHT: BIOL ABS. The bacterial biodetection system SOS-LUX-TEST has been developed for rapid detection of environmental genotoxins. This cellular bioassay is based on the receptor reporter principle with the SOS system as receptor sensitive to DNA damage and the bioluminescence system giving the optical signal which is registered by an appropriate detector. The lux-operon of a marine photobacteria (Photobacterium leiognathi) containing the whole information for the synthesis of the bacterial luciferase and its s uous incubation and shaking during the registration of the signal. The kinetics of bioluminescence was always monitored over a period of at least 5 h. Typical model compounds with various DNA damaging potencies were tested.,Microscale application of the SOS-LUX-TEST as biosensor for genotoxic agents Abs: BIOSIS COPYRIGHT: BIOL ABS. The bacterial biodetection system SOS-LUX-TEST has been developed for rapid detection of environmental genotoxins. This cellular bioassay is based on the receptor reporter principle with the SOS system as receptor sensitive to DNA damage and the bioluminescence system giving the optical signal which is registered by an appropriate detector. The lux-operon of a marine photobacteria (Photobacterium leiognathi) containing the whole information for the synthesis of the bacterial luciferase and its s uous incubation and shaking during the registration of the signal. The kinetics of bioluminescence was always monitored over a period of at least 5 h. Typical model compounds with various DNA damaging potencies were tested.
1236892,Marcusson et al. 1999,Chronic fatigue syndrome and nickel allergy,"BIOSIS COPYRIGHT: BIOL ABS. 50 patients with chronic fatigue syndrome (CFS) and 73 controls were patch tested with 8 metal allergens. We found an overrepresentation of allergies among the CFS patients, which was not significant. However, allergy to nickel occurred in 36% of patients in the CFS group and in 19% of subjects in the control group (p<0.05). The high frequency of nickel allergy was more noteworthy in females in the CFS group than among female controls (52% and 24%, respectively, p<0.05). Similarly, in the males","Chronic fatigue syndrome and nickel allergy Abs: BIOSIS COPYRIGHT: BIOL ABS. 50 patients with chronic fatigue syndrome (CFS) and 73 controls were patch tested with 8 metal allergens. We found an overrepresentation of allergies among the CFS patients, which was not significant. However, allergy to nickel occurred in 36% of patients in the CFS group and in 19% of subjects in the control group (p<0.05). The high frequency of nickel allergy was more noteworthy in females in the CFS group than among female controls (52% and 24%, respectively, p<0.05). Similarly, in the males"
1236891,Rojickova-Padrtova and  Marsalek 1999,Selection and sensitivity comparisons of algal species for toxicity testing,"BIOSIS COPYRIGHT: BIOL ABS. The sensitivity of 7 algal species representing the green and blue green algae was evaluated using EC50 values from the toxicity tests on 3 metal compounds (K2Cr2O7, CuSO45H2O, ZnSO4) and 3 formulated products of herbicides (oxyfluorphene, pendimethaline, atrazine). The growth inhibition tests were conducted in microplates. The variability in sensitivity was as high as 5 orders of magnitude (oxyfluorphene). The principal component analysis separated the cyanobacterial strain (Synechococcus leopo domonas reinhardtii). The differences in sensitivity among the species of the second group were not distinctive. Therefore, any of these species, because of their similar sensitivity, can be recommended as test organisms in the single algal assays. However, toxicity results showed that none of these species can represent all the phylogenetic (taxonomic) groups of algae.","Selection and sensitivity comparisons of algal species for toxicity testing Abs: BIOSIS COPYRIGHT: BIOL ABS. The sensitivity of 7 algal species representing the green and blue green algae was evaluated using EC50 values from the toxicity tests on 3 metal compounds (K2Cr2O7, CuSO45H2O, ZnSO4) and 3 formulated products of herbicides (oxyfluorphene, pendimethaline, atrazine). The growth inhibition tests were conducted in microplates. The variability in sensitivity was as high as 5 orders of magnitude (oxyfluorphene). The principal component analysis separated the cyanobacterial strain (Synechococcus leopo domonas reinhardtii). The differences in sensitivity among the species of the second group were not distinctive. Therefore, any of these species, because of their similar sensitivity, can be recommended as test organisms in the single algal assays. However, toxicity results showed that none of these species can represent all the phylogenetic (taxonomic) groups of algae."
1236890,Wroñska-Nofer et al. 1999,"Prooxidative and genotoxic effect of transition metals (cadmium, nickel, chromium, and vanadium) in mice","Aim: Genotoxic effect of cadmium (II), nickel (II), chromium (VI), and vanadium (V) were evaluated in Balb C mice. Material and methods: Animals were given intraperitoneally, 30 h before testing, following doses of the metal salts: CdCl2x2.5 H2O - 18 ?mol ? 2 mg Cd/kg; NiCl2x6 H2O- 200 ?mol ? 12 mg Ni/kg; K2Cr2O7 - 400 ?mol ? 20.8 mg Cr/kg and NH4VO3- 20 ?mol -- 23.4 mg V/kg body weight. Hepatic oxidant status was assessed on a basis of determination of the activity of 7-ethoxycoumarin O-deethylase (ECOD) and glutathione- (GSH) S-transferase as markers of oxidative metabolic efficiency. In addition, lipid peroxidation rate as well as levels of GSH and activity of GSH peroxidase (primary constitutive antioxidants) and heme oxygenase (secondary, inducible antioxidant) were determined. Bone marrow micronucleus test was used for evaluation of the genotoxic effect. Results: The metal salts in applied single doses failed to affect activities of ECOD and GSH-S-transferase but deranged liver oxidant status. The metals-mediated prooxidative effect resulted from: stimulation of lipid peroxidation by 24 - 146%); decrease of the antioxidative activity (by 17 - 35%) of GSH-peroxidase, a lipid peroxides scavenger. The latter was accompanied by a compensating induction/increase of activity (by 42 - 73%) of the heme oxygenase catalyzing heme degradation to antioxidant bile pigments. Cadmium (II), nickel (II), and chromium (VI) exerted genotoxic effect as inferred from a several time increase of frequency of micronucleated polychromatic erythrocytes in bone marrow whereas vanadium (V) failed to induce the genotoxic effect. Conclusion: It is concluded that the in vivo genotoxic effects of transition metals may be related in part to the enhancement of prooxidative processes and to the depletion of anti-oxidative reserves.","Prooxidative and genotoxic effect of transition metals (cadmium, nickel, chromium, and vanadium) in mice Abs: Aim: Genotoxic effect of cadmium (II), nickel (II), chromium (VI), and vanadium (V) were evaluated in Balb C mice. Material and methods: Animals were given intraperitoneally, 30 h before testing, following doses of the metal salts: CdCl2x2.5 H2O - 18 ?mol ? 2 mg Cd/kg; NiCl2x6 H2O- 200 ?mol ? 12 mg Ni/kg; K2Cr2O7 - 400 ?mol ? 20.8 mg Cr/kg and NH4VO3- 20 ?mol -- 23.4 mg V/kg body weight. Hepatic oxidant status was assessed on a basis of determination of the activity of 7-ethoxycoumarin O-deethylase (ECOD) and glutathione- (GSH) S-transferase as markers of oxidative metabolic efficiency. In addition, lipid peroxidation rate as well as levels of GSH and activity of GSH peroxidase (primary constitutive antioxidants) and heme oxygenase (secondary, inducible antioxidant) were determined. Bone marrow micronucleus test was used for evaluation of the genotoxic effect. Results: The metal salts in applied single doses failed to affect activities of ECOD and GSH-S-transferase but deranged liver oxidant status. The metals-mediated prooxidative effect resulted from: stimulation of lipid peroxidation by 24 - 146%); decrease of the antioxidative activity (by 17 - 35%) of GSH-peroxidase, a lipid peroxides scavenger. The latter was accompanied by a compensating induction/increase of activity (by 42 - 73%) of the heme oxygenase catalyzing heme degradation to antioxidant bile pigments. Cadmium (II), nickel (II), and chromium (VI) exerted genotoxic effect as inferred from a several time increase of frequency of micronucleated polychromatic erythrocytes in bone marrow whereas vanadium (V) failed to induce the genotoxic effect. Conclusion: It is concluded that the in vivo genotoxic effects of transition metals may be related in part to the enhancement of prooxidative processes and to the depletion of anti-oxidative reserves."
1236887,Geier et al. 1999,"Patch test reactions at D4, D5 and D6","BIOSIS COPYRIGHT: BIOL ABS. In this retrospective study, patch test reactions in 3 groups of patients were analysed, in order to obtain information on the best day for the 2nd patch-test reading after day 2 (D2), on the usefulness of additional readings after D3, and on the dependence of patch-test reactions at D4, D5, or D6 on allergen and/or patient characteristics. In the years 1990 to 1995, patch tests were routinely read at D3 and D4 in 1096 patients, at D3 and D5 in 1243 patients, and at D3 and D6 in 1136 patients. I ndividual allergens showed wide differences in this connection. Neomycin sulfate, cobalt salts, and p-phenylenediamine can be characterized as slow allergens, with more reactions increasing than diminishing from D3 to the later readings. With fragrance mix and balsam of Peru, the opposite pattern occurred. In all subgroups of patients, and with most allergens, the gain in positive reactions was biggest when an additional reading was performed at DS. We conclude that for a single","Patch test reactions at D4, D5 and D6 Abs: BIOSIS COPYRIGHT: BIOL ABS. In this retrospective study, patch test reactions in 3 groups of patients were analysed, in order to obtain information on the best day for the 2nd patch-test reading after day 2 (D2), on the usefulness of additional readings after D3, and on the dependence of patch-test reactions at D4, D5, or D6 on allergen and/or patient characteristics. In the years 1990 to 1995, patch tests were routinely read at D3 and D4 in 1096 patients, at D3 and D5 in 1243 patients, and at D3 and D6 in 1136 patients. I ndividual allergens showed wide differences in this connection. Neomycin sulfate, cobalt salts, and p-phenylenediamine can be characterized as slow allergens, with more reactions increasing than diminishing from D3 to the later readings. With fragrance mix and balsam of Peru, the opposite pattern occurred. In all subgroups of patients, and with most allergens, the gain in positive reactions was biggest when an additional reading was performed at DS. We conclude that for a single"
1236886,Trattner et al. 1999,Screening patch tests for pigmented contact dermatitis in Israel,"BIOSIS COPYRIGHT: BIOL ABS. Pigmented contact dermatitis has been found to be caused by fragrances, cosmetics, washing powders, azo dyes in textiles, and rubber products in selected groups of patients. The aim of this study was to run screening patch tests in an unselected group of patients with pigmented contact dermatitis (n=29) encountered in our center over a 2-year period. The test series included the European standard, cosmetics, fragrance, Scandinavian photo, and personal products. 21 patients had a positive reactio","Screening patch tests for pigmented contact dermatitis in Israel Abs: BIOSIS COPYRIGHT: BIOL ABS. Pigmented contact dermatitis has been found to be caused by fragrances, cosmetics, washing powders, azo dyes in textiles, and rubber products in selected groups of patients. The aim of this study was to run screening patch tests in an unselected group of patients with pigmented contact dermatitis (n=29) encountered in our center over a 2-year period. The test series included the European standard, cosmetics, fragrance, Scandinavian photo, and personal products. 21 patients had a positive reactio"
1236885,Hutchinson et al. 1999,Overcoming humidity dependence of the chromium trioxide converter used in luminol-based nitric oxide detection,"BIOSIS COPYRIGHT: BIOL ABS. The surface-atmosphere exchange of gaseous NOx (NO + NO2) is commonly measured by chamber methods that employ a portable luminol-based NO2 detector. Detection of NO depends on its prior oxidation to NO2 by CrO3 with efficiency that depends on sample relative humidity. We found that inadequate drying of wet chamber air samples, and consequent changes in NO oxidation efficiency, often contributes to observed apparent shifts in the response of commercially available detectors in the field. Our i nstrument's performance was improved when the water vapor gradient across its membrane dryer was enhanced by replacing the restrictor on the air inlet of the dryer's shell with a desiccant column, and then increasing ambient air flow through the shell to approximately equal the sample air flow rate. We also demonstrated that pumice is the preferred CrO3 support material for luminol-based detection of NO in chamber air samples; advantages include low cost, superior physical propertie","Overcoming humidity dependence of the chromium trioxide converter used in luminol-based nitric oxide detection Abs: BIOSIS COPYRIGHT: BIOL ABS. The surface-atmosphere exchange of gaseous NOx (NO + NO2) is commonly measured by chamber methods that employ a portable luminol-based NO2 detector. Detection of NO depends on its prior oxidation to NO2 by CrO3 with efficiency that depends on sample relative humidity. We found that inadequate drying of wet chamber air samples, and consequent changes in NO oxidation efficiency, often contributes to observed apparent shifts in the response of commercially available detectors in the field. Our i nstrument's performance was improved when the water vapor gradient across its membrane dryer was enhanced by replacing the restrictor on the air inlet of the dryer's shell with a desiccant column, and then increasing ambient air flow through the shell to approximately equal the sample air flow rate. We also demonstrated that pumice is the preferred CrO3 support material for luminol-based detection of NO in chamber air samples; advantages include low cost, superior physical propertie"
1236882,Carlisle et al. 1999,Inhibitors of Cr(VI)-induced apoptosis do not increase long term survival of human lung cells,BIOSIS COPYRIGHT: BIOL ABS. RRM MEETING ABSTRACT HUMAN MOUSE BIOCHEMISTRY AND BIOPHYSICS SODIUM CHROMATE RESPIRATORY SYSTEM H7 FUMONISIN B SPHINGOSINE-1-PHOSPHATE P53 PROTEIN ANNEXINVI DERMAL FIBROBLASTS LUNG CELLS INTEGUMENTARY SYSTEM INTEGUMENTARY SYSTEM APOPTOSIS RESPIRATORY SYSTEM,Inhibitors of Cr(VI)-induced apoptosis do not increase long term survival of human lung cells Abs: BIOSIS COPYRIGHT: BIOL ABS. RRM MEETING ABSTRACT HUMAN MOUSE BIOCHEMISTRY AND BIOPHYSICS SODIUM CHROMATE RESPIRATORY SYSTEM H7 FUMONISIN B SPHINGOSINE-1-PHOSPHATE P53 PROTEIN ANNEXINVI DERMAL FIBROBLASTS LUNG CELLS INTEGUMENTARY SYSTEM INTEGUMENTARY SYSTEM APOPTOSIS RESPIRATORY SYSTEM
1236878,Schembri et al. 1999,Bioaccumulation of heavy metals by fimbrial designer adhesins,"BIOSIS COPYRIGHT: BIOL ABS. Naturally occurring adhesins bind to specific molecular targets in a lock-and-key fashion due to the composition of the binding domain of the adhesin. By introduction of random peptide libraries in a suitable surface exposed carrier protein it is possible to create and select designer adhesins with novel binding affinities. Type 1 fimbriae are surface organelles of Escherichia coli which mediate D-mannose sensitive binding to different host surfaces through the FimH adhesin, an integral part of these organelles. We have studied the ability of the FimH adhesin to display random peptide sequences. By serial selection and enrichment procedures specific sequences were identified which conferred the ability on recombinant cells to adhere to various metal oxides (PbO2, CoO, MnO2, Cr2O3). The properties inherent in these sequences permitted the distinct recognition of metals to varying degrees, indicating that this system allows for the isolation of peptide sequences with a va","Bioaccumulation of heavy metals by fimbrial designer adhesins Abs: BIOSIS COPYRIGHT: BIOL ABS. Naturally occurring adhesins bind to specific molecular targets in a lock-and-key fashion due to the composition of the binding domain of the adhesin. By introduction of random peptide libraries in a suitable surface exposed carrier protein it is possible to create and select designer adhesins with novel binding affinities. Type 1 fimbriae are surface organelles of Escherichia coli which mediate D-mannose sensitive binding to different host surfaces through the FimH adhesin, an integral part of these organelles. We have studied the ability of the FimH adhesin to display random peptide sequences. By serial selection and enrichment procedures specific sequences were identified which conferred the ability on recombinant cells to adhere to various metal oxides (PbO2, CoO, MnO2, Cr2O3). The properties inherent in these sequences permitted the distinct recognition of metals to varying degrees, indicating that this system allows for the isolation of peptide sequences with a va"
1236876,Shi et al. 1999,Reduction of chromium (VI) and its relationship to carcinogenesis,"BIOSIS COPYRIGHT: BIOL ABS. Although Cr(VI)-containing compounds are well-documented carcinogens, their mechanism of action is still not well understood. Recent studies have suggested that reduction of Cr(VI) to its lower oxidation states and related free-radical reactions play an important role in carcinogenesis. This article summarizes recent studies on (1) the reduction of Cr(VI) by ascorbate, diol- and thiol-containing molecules, certain flavoenzymes, cell organelles, intact cells, and whole animals; (2) free-radical production with emphasis on hydroxy radical generation via Fenton or Haber-Weiss type reactions; and (3) free-radical-induced cellular damage, such as DNA strand breaks, hydroxylation of 2'-deoxyguanosine, and activation of nuclear transcription factor kappaB.","Reduction of chromium (VI) and its relationship to carcinogenesis Abs: BIOSIS COPYRIGHT: BIOL ABS. Although Cr(VI)-containing compounds are well-documented carcinogens, their mechanism of action is still not well understood. Recent studies have suggested that reduction of Cr(VI) to its lower oxidation states and related free-radical reactions play an important role in carcinogenesis. This article summarizes recent studies on (1) the reduction of Cr(VI) by ascorbate, diol- and thiol-containing molecules, certain flavoenzymes, cell organelles, intact cells, and whole animals; (2) free-radical production with emphasis on hydroxy radical generation via Fenton or Haber-Weiss type reactions; and (3) free-radical-induced cellular damage, such as DNA strand breaks, hydroxylation of 2'-deoxyguanosine, and activation of nuclear transcription factor kappaB."
1236875,Romaguera and  Vilaplana 1998,Contact dermatitis in children: 6 years experience (1992-1997),"BIOSIS COPYRIGHT: BIOL ABS. We report the results of patch tests carried out over the last 6 years (1992-1997) on 141 children. This corresponds to 2.8% of the total patients who were patch tested in our Allergy Department (5,014). These 141 children were patch tested using the TRUE TestTM standard series and an additional allergen, metallic mercury Allergens from the Chemotechnique medicaments, cosmetics, plants and shoe series were added in some. The most frequent localization of eczema was to the feet, face and hands and the most frequent suspected causes were costume jewelry, footwear, topical medicaments and cosmetics. The most frequent allergens, assessed by degree of relevance, were first, nickel, followed by cobalt, mercurials (thimerosal and metallic mercury), fragrance and rubber chemicals (naphthyl mix, mercapto mix, carba mix and PPD mix). 13 children, 18% of the total, between the ages of 12 and 14 years, showed positivities relevant to some occupation, i.e., metalworking, building, h","Contact dermatitis in children: 6 years experience (1992-1997) Abs: BIOSIS COPYRIGHT: BIOL ABS. We report the results of patch tests carried out over the last 6 years (1992-1997) on 141 children. This corresponds to 2.8% of the total patients who were patch tested in our Allergy Department (5,014). These 141 children were patch tested using the TRUE TestTM standard series and an additional allergen, metallic mercury Allergens from the Chemotechnique medicaments, cosmetics, plants and shoe series were added in some. The most frequent localization of eczema was to the feet, face and hands and the most frequent suspected causes were costume jewelry, footwear, topical medicaments and cosmetics. The most frequent allergens, assessed by degree of relevance, were first, nickel, followed by cobalt, mercurials (thimerosal and metallic mercury), fragrance and rubber chemicals (naphthyl mix, mercapto mix, carba mix and PPD mix). 13 children, 18% of the total, between the ages of 12 and 14 years, showed positivities relevant to some occupation, i.e., metalworking, building, h"
1236874,Leino et al. 1998,Occupational skin and respiratory diseases among hairdressers,"Objectives: The occurrence and causes of hairdressers' occupational skin and respiratory diseases were studied. Methods: Of a random sample of 500 female hairdressers aged 15-54 years, 355 were available for study. Of the 189 reporting work-related skin and respiratory symptoms in a computer-aided telephone interview on exposure and health, 130 underwent a physical examination, lung function tests, prick and patch testing, and nasal and lung provocation tests. An occupational disease was diagnosed when the causality between exposure and disease was probable and the clinical tests supported the diagnosis. Results: The telephone interview revealed a life-time prevalence of 16.9% for hand dermatoses, 16.9% for allergic rhinitis, and 4.5% for asthma among the hairdressers. In the clinical investigations, the prevalence was 2.8% for occupational dermatoses, 1.7% for occupational rhinitis, and 0.8% for occupational asthma. Ammonium persulfate caused 90% of the respiratory diseases and 27% of the hand dermatoses. Paraphenylenediamine, natural rubber latex, and skin irritation were also causes of hand dermatitis. Allergy to human dandruff (8.6%) and Pityrosporum ovale (12.1%) was common. Previously diagnosed atopic diseases increased the risk for occupational skin or respiratory disease 3-fold (odds ratio 2.9, 95% confidence interval 1.1-7.9). Of the cases, 37.5% (6 of 16 persons) had to change occupations during a 3-year follow-up. Conclusions: Work-related skin and respiratory symptoms are common among hairdressers. Often a specific cause (eg, ammonium persulfate) can be found if occupational diseases are suspected and diagnosed. Hairdressers with atopic diseases are at risk of developing occupational skin and respiratory diseases.","Occupational skin and respiratory diseases among hairdressers Abs: Objectives: The occurrence and causes of hairdressers' occupational skin and respiratory diseases were studied. Methods: Of a random sample of 500 female hairdressers aged 15-54 years, 355 were available for study. Of the 189 reporting work-related skin and respiratory symptoms in a computer-aided telephone interview on exposure and health, 130 underwent a physical examination, lung function tests, prick and patch testing, and nasal and lung provocation tests. An occupational disease was diagnosed when the causality between exposure and disease was probable and the clinical tests supported the diagnosis. Results: The telephone interview revealed a life-time prevalence of 16.9% for hand dermatoses, 16.9% for allergic rhinitis, and 4.5% for asthma among the hairdressers. In the clinical investigations, the prevalence was 2.8% for occupational dermatoses, 1.7% for occupational rhinitis, and 0.8% for occupational asthma. Ammonium persulfate caused 90% of the respiratory diseases and 27% of the hand dermatoses. Paraphenylenediamine, natural rubber latex, and skin irritation were also causes of hand dermatitis. Allergy to human dandruff (8.6%) and Pityrosporum ovale (12.1%) was common. Previously diagnosed atopic diseases increased the risk for occupational skin or respiratory disease 3-fold (odds ratio 2.9, 95% confidence interval 1.1-7.9). Of the cases, 37.5% (6 of 16 persons) had to change occupations during a 3-year follow-up. Conclusions: Work-related skin and respiratory symptoms are common among hairdressers. Often a specific cause (eg, ammonium persulfate) can be found if occupational diseases are suspected and diagnosed. Hairdressers with atopic diseases are at risk of developing occupational skin and respiratory diseases."
1236871,Togulga 1998,The short-term toxicity of two toxicants to Artemia nauplii,"BIOSIS COPYRIGHT: BIOL ABS. In this study, the short-term toxicities of sodium lauryl sulphate (an anionic detergent) and potassium dichromate on instar I and mixed instar II-III nauplii populations of Artemia were investigated. The comparisons between our results and the ARC-test (Artemia Reference Center) protocol show our experiments to be acceptable for acute toxicity standardization.","The short-term toxicity of two toxicants to Artemia nauplii Abs: BIOSIS COPYRIGHT: BIOL ABS. In this study, the short-term toxicities of sodium lauryl sulphate (an anionic detergent) and potassium dichromate on instar I and mixed instar II-III nauplii populations of Artemia were investigated. The comparisons between our results and the ARC-test (Artemia Reference Center) protocol show our experiments to be acceptable for acute toxicity standardization."
1236870,Yang et al. 1998,Behavior of hazardous and radioactive metals in a laboratory furnace and a demonstration-scale incinerator,"BIOSIS COPYRIGHT: BIOL ABS. The behaviors of hazardous and radioactive metals in analytical and real combustion conditions were observed to understand their vaporization and to predict their release into the atmosphere at a real incineration plant. In the laboratory furnace experiment, vaporization fluxes were obtained based on the measurement of weight losses with temperatures. Vaporization fluxes were compared to maximum theoretical fluxes obtained from the Herz-Knudsen's kinetic theory of gas. The vaporization coefficient, alpha, for volatile metal chloride appears to be a characteristic value of the evaporating substance, not varying with increasing temperatures. With some theoretical considerations on interfacial equilibrium, mass transfer coefficient of vaporization, KG, was determined as a function of absolute temperature. To evaluate the behavior of metals and radionuclides in an incinerator and off-gas treatment system, test burns of simulated waste containing several toxic metals and ra","Behavior of hazardous and radioactive metals in a laboratory furnace and a demonstration-scale incinerator Abs: BIOSIS COPYRIGHT: BIOL ABS. The behaviors of hazardous and radioactive metals in analytical and real combustion conditions were observed to understand their vaporization and to predict their release into the atmosphere at a real incineration plant. In the laboratory furnace experiment, vaporization fluxes were obtained based on the measurement of weight losses with temperatures. Vaporization fluxes were compared to maximum theoretical fluxes obtained from the Herz-Knudsen's kinetic theory of gas. The vaporization coefficient, alpha, for volatile metal chloride appears to be a characteristic value of the evaporating substance, not varying with increasing temperatures. With some theoretical considerations on interfacial equilibrium, mass transfer coefficient of vaporization, KG, was determined as a function of absolute temperature. To evaluate the behavior of metals and radionuclides in an incinerator and off-gas treatment system, test burns of simulated waste containing several toxic metals and ra"
1236867,Marques et al. 1998,Analytical methodologies for chromium speciation in solid matrices: A survey of literature,"BIOSIS COPYRIGHT: BIOL ABS. The analytical literature about chromium speciation in solid samples has been surveyed. From 451 articles published on the speciation of chromium from 1983 to 1997, the methodologies to do speciation in solids after sample pretreatment are discussed, through consideration of the types of samples and their dissolution, the analytical techniques employed for chromium measurement, and the figures of merit of the 86 papers reported in the Analytical Abstracts data base.","Analytical methodologies for chromium speciation in solid matrices: A survey of literature Abs: BIOSIS COPYRIGHT: BIOL ABS. The analytical literature about chromium speciation in solid samples has been surveyed. From 451 articles published on the speciation of chromium from 1983 to 1997, the methodologies to do speciation in solids after sample pretreatment are discussed, through consideration of the types of samples and their dissolution, the analytical techniques employed for chromium measurement, and the figures of merit of the 86 papers reported in the Analytical Abstracts data base."
1236863,Piontek 1998,Application of Dugesia tigrina Girard in toxicological studies of aquatic environments,"BIOSIS COPYRIGHT: BIOL ABS. Experiments were done on the planarian Dugesia ligrina Girard. The species remarkable regenerative abilities were used for the working out of techniques of an artificial population increase through transverse fission. Optimal laboratory conditions of D. ligrina culturing. size of flasks, water quality, types of diet and ways of feeding were found. Observations were made on the effect of temperature on reproduction. Regeneration of the body parts lasted 10 days at 20-21?C, regaining of the original size occurred after 18 days. Physiological state of D. tigrina was tested with potassium dichromate. Sensitivity of planarians to the poison depends on age, stabilized condition was observed for individuals 18-42 days old. The effect of D. tigrina starvation on its physiological condition was estimated. The planarian revealed high resistance to the shortage of food.","Application of Dugesia tigrina Girard in toxicological studies of aquatic environments Abs: BIOSIS COPYRIGHT: BIOL ABS. Experiments were done on the planarian Dugesia ligrina Girard. The species remarkable regenerative abilities were used for the working out of techniques of an artificial population increase through transverse fission. Optimal laboratory conditions of D. ligrina culturing. size of flasks, water quality, types of diet and ways of feeding were found. Observations were made on the effect of temperature on reproduction. Regeneration of the body parts lasted 10 days at 20-21?C, regaining of the original size occurred after 18 days. Physiological state of D. tigrina was tested with potassium dichromate. Sensitivity of planarians to the poison depends on age, stabilized condition was observed for individuals 18-42 days old. The effect of D. tigrina starvation on its physiological condition was estimated. The planarian revealed high resistance to the shortage of food."
1236862,Huo et al. 1998,Determination and correction of analytical biases and study on chemical mechanisms in the analysis of Cr(VI) in soil samples using EPA protocols,"BIOSIS COPYRIGHT: BIOL ABS. EPA Methods 3060A (alkaline extraction) and 7196A (colorimetric measurement) currently constitute a pair of protocols for the measurement of Cr(VI) in environmental soil samples in EPA RCRA SW-846 Update III. To identify the sources of possible biases, we applied the newly developed Speciated Isotope Dilution Mass Spectrometry (SIDMS) as an alternative detection method to Method 7196A. SIDMS is capable of correcting for species transformation, while Method 7196A is not. In Method 3060A, soluble Cr(III) could be oxidized during extraction, resulting in positive errors of Cr(VI); Cr(VI) could be lost or reduced during neutralization, leading to negative errors of Cr(VI). When sand and soil extracts were analyzed, low recoveries were obtained with Method 7196A. However, SIDMS achieved approximately 100% recoveries. The influence of some soil matrix components on the detection of Cr(VI) using Method 7196A has been evaluated. As expected, reducing agents could cause low reco","Determination and correction of analytical biases and study on chemical mechanisms in the analysis of Cr(VI) in soil samples using EPA protocols Abs: BIOSIS COPYRIGHT: BIOL ABS. EPA Methods 3060A (alkaline extraction) and 7196A (colorimetric measurement) currently constitute a pair of protocols for the measurement of Cr(VI) in environmental soil samples in EPA RCRA SW-846 Update III. To identify the sources of possible biases, we applied the newly developed Speciated Isotope Dilution Mass Spectrometry (SIDMS) as an alternative detection method to Method 7196A. SIDMS is capable of correcting for species transformation, while Method 7196A is not. In Method 3060A, soluble Cr(III) could be oxidized during extraction, resulting in positive errors of Cr(VI); Cr(VI) could be lost or reduced during neutralization, leading to negative errors of Cr(VI). When sand and soil extracts were analyzed, low recoveries were obtained with Method 7196A. However, SIDMS achieved approximately 100% recoveries. The influence of some soil matrix components on the detection of Cr(VI) using Method 7196A has been evaluated. As expected, reducing agents could cause low reco"
1236861,Friis et al. 1998,Evaluation of elemental composition of algal biomass as toxical endpoint,"BIOSIS COPYRIGHT: BIOL ABS. Freeze dried algal biomass was analysed with an organic elemental analysis (CHNS) in order to determine whether chemical stress could be detected as changes in gross cellular composition. Results showed that an LOEC for potassium dichromate of 0,21 mg/l was statistically different from a NOEC of 0,10 mg/l. The elemental analysis method could be improved if the final algal density in the batch cultures was kept low (<105 cell/ml). The remaining problem is to get sufficient biomass to perform the elemental analysis. The study demonstrates the potential of elemental analysis applied as endpoint for algal toxicity and defines the optimal conditions for simultaneous CHNS determination, furthermore proposals for future investigations are given.","Evaluation of elemental composition of algal biomass as toxical endpoint Abs: BIOSIS COPYRIGHT: BIOL ABS. Freeze dried algal biomass was analysed with an organic elemental analysis (CHNS) in order to determine whether chemical stress could be detected as changes in gross cellular composition. Results showed that an LOEC for potassium dichromate of 0,21 mg/l was statistically different from a NOEC of 0,10 mg/l. The elemental analysis method could be improved if the final algal density in the batch cultures was kept low (<105 cell/ml). The remaining problem is to get sufficient biomass to perform the elemental analysis. The study demonstrates the potential of elemental analysis applied as endpoint for algal toxicity and defines the optimal conditions for simultaneous CHNS determination, furthermore proposals for future investigations are given."
1236860,De Coen et al. 1998,The use of biomarkers in Daphnia magna toxicity testing. III. Rapid toxicity testing of pure chemicals and sediment pore waters using ingestion and digestive enzyme activity,"BIOSIS COPYRIGHT: BIOL ABS. In this study, 4 rapid (90 min) toxicity tests were developed using ingestion and digestive enzyme activity of Daphnia magna juveniles. Ingestion activity was assessed using fluorescent labelled latex micro-beads and digestive enzyme activity (trypsin, beta-galactosidase and esterase) was measured in homogenates using chromogenic (N-benzoyl-L-arginine-4-nitroanilide) and fluorogenic (4-methylumbelliferyl-B-D-galactoside and fluorescein diacetate) substrates. All assays and toxicity endpoints were evaluated for their potential use as routine toxicity testing tools for pure chemicals and sediment pore waters. The observed high correlation coefficients (r2>0.9) between the short-term toxicity values and the acute toxicity endpoint (24h EC50) for pure chemicals suggests that these biomarker-based assays are good predictors of acute toxicity levels to D. magna. In the sediment pore water toxicity tests, ingestion activity was generally more sensitive than the conventional","The use of biomarkers in Daphnia magna toxicity testing. III. Rapid toxicity testing of pure chemicals and sediment pore waters using ingestion and digestive enzyme activity Abs: BIOSIS COPYRIGHT: BIOL ABS. In this study, 4 rapid (90 min) toxicity tests were developed using ingestion and digestive enzyme activity of Daphnia magna juveniles. Ingestion activity was assessed using fluorescent labelled latex micro-beads and digestive enzyme activity (trypsin, beta-galactosidase and esterase) was measured in homogenates using chromogenic (N-benzoyl-L-arginine-4-nitroanilide) and fluorogenic (4-methylumbelliferyl-B-D-galactoside and fluorescein diacetate) substrates. All assays and toxicity endpoints were evaluated for their potential use as routine toxicity testing tools for pure chemicals and sediment pore waters. The observed high correlation coefficients (r2>0.9) between the short-term toxicity values and the acute toxicity endpoint (24h EC50) for pure chemicals suggests that these biomarker-based assays are good predictors of acute toxicity levels to D. magna. In the sediment pore water toxicity tests, ingestion activity was generally more sensitive than the conventional"
1236859,Blasiak et al. 1999,DNA damage in human gastric mucosal cells exposed to chromium and curcumin,,DNA damage in human gastric mucosal cells exposed to chromium and curcumin Abs: 
1236858,Basketter et al. 1999,The identification of metal allergens in the local lymph node assay,BIOSIS COPYRIGHT: BIOL ABS. RRM THE IDENTIFICATION OF METAL ALLERGENS IN THE LOCAL LYMPH NODE ASSAYYMEETING ABSTRACT MEETING POSTER MURINE ANIMAL MODEL LOCAL LYMPH NODE ASSAY METHODOLOGY IMMUNE SYSTEM TOXICOLOGY GOLD (III) CHLORIDE METAL CONTACT ALLERGEN BERYLLIUM SULFATE TETRAHYDRATE POTASSIUM DICHROMATE COPPER (II) CHLORIDE MERCURY (II) CHLORIDE AMMONIUM TETRACHLOROPLATINATE COBALT CHLORIDE TIN CHLORIDE ALUMINUM CHLORIDE MANGANESE CHLORIDE NICKEL CHLORIDE LEAD ACETATE ZINC SULFATE SKIN SENSITIZATION ANALYTICAL METHOD,The identification of metal allergens in the local lymph node assay Abs: BIOSIS COPYRIGHT: BIOL ABS. RRM THE IDENTIFICATION OF METAL ALLERGENS IN THE LOCAL LYMPH NODE ASSAYYMEETING ABSTRACT MEETING POSTER MURINE ANIMAL MODEL LOCAL LYMPH NODE ASSAY METHODOLOGY IMMUNE SYSTEM TOXICOLOGY GOLD (III) CHLORIDE METAL CONTACT ALLERGEN BERYLLIUM SULFATE TETRAHYDRATE POTASSIUM DICHROMATE COPPER (II) CHLORIDE MERCURY (II) CHLORIDE AMMONIUM TETRACHLOROPLATINATE COBALT CHLORIDE TIN CHLORIDE ALUMINUM CHLORIDE MANGANESE CHLORIDE NICKEL CHLORIDE LEAD ACETATE ZINC SULFATE SKIN SENSITIZATION ANALYTICAL METHOD
1236857,Cox et al. 1999,Comparison of three stool fixatives for the detection of microsporidia by PCR,BIOSIS COPYRIGHT: BIOL ABS. RRM COMPARISON OF THREE STOOL FIXATIVES FOR THE DETECTION OF MICROSPORIDIA BY PCRYMEETING ABSTRACT MEETING POSTER ENCEPHALITOZOON-INTESTINALIS PARASITE PCR POLYMERASE CHAIN REACTION POTASSIUM DICHROMATE STOOL FIXATIVE BUFFERED FORMALIN ETHANOL METHODOLOGY PARASITOLOGY DNA AMPLIFICATION DIAGNOSTIC METHOD IN-SITU RECOMBINANT GENE EXPRESSION DETECTION SEQUENCING TECHNIQUES,Comparison of three stool fixatives for the detection of microsporidia by PCR Abs: BIOSIS COPYRIGHT: BIOL ABS. RRM COMPARISON OF THREE STOOL FIXATIVES FOR THE DETECTION OF MICROSPORIDIA BY PCRYMEETING ABSTRACT MEETING POSTER ENCEPHALITOZOON-INTESTINALIS PARASITE PCR POLYMERASE CHAIN REACTION POTASSIUM DICHROMATE STOOL FIXATIVE BUFFERED FORMALIN ETHANOL METHODOLOGY PARASITOLOGY DNA AMPLIFICATION DIAGNOSTIC METHOD IN-SITU RECOMBINANT GENE EXPRESSION DETECTION SEQUENCING TECHNIQUES
1236856,Singh et al. 1999,Quantitation of metal-DNA adducts by inductively coupled plasma mass spectrometry as a biomarker for exposure to toxic metals,BIOSIS COPYRIGHT: BIOL ABS. RRM QUANTITATION OF METAL-DNA ADDUCTS BY INDUCTIVELY COUPLED PLASMA MASS SPECTROMETRY AS A BIOMARKER FOR EXPOSURE TO TOXIC METALSYMEETING ABSTRACT HUMAN MOLECULAR GENETICS INDUCTIVELY COUPLED PLASMA MASS SPECTROMETRY METAL DNA ADDUCTS RESPIRATORY SYSTEM TOXICOLOGY LUNG FIBROBLASTS LEAD CHROMATE MUTAGEN SODIUM CHROMATE CHROMIUM HEAVY METAL LEAD ANALYTICAL METHOD RESPIRATORY SYSTEM,Quantitation of metal-DNA adducts by inductively coupled plasma mass spectrometry as a biomarker for exposure to toxic metals Abs: BIOSIS COPYRIGHT: BIOL ABS. RRM QUANTITATION OF METAL-DNA ADDUCTS BY INDUCTIVELY COUPLED PLASMA MASS SPECTROMETRY AS A BIOMARKER FOR EXPOSURE TO TOXIC METALSYMEETING ABSTRACT HUMAN MOLECULAR GENETICS INDUCTIVELY COUPLED PLASMA MASS SPECTROMETRY METAL DNA ADDUCTS RESPIRATORY SYSTEM TOXICOLOGY LUNG FIBROBLASTS LEAD CHROMATE MUTAGEN SODIUM CHROMATE CHROMIUM HEAVY METAL LEAD ANALYTICAL METHOD RESPIRATORY SYSTEM
1236855,Katsarou et al. 1999,Frequency of immediate reactions to the European standard series,"BIOSIS COPYRIGHT: BIOL ABS. Immediate contact reactions (contact urticaria) can occur after skin contact with a wide range of substances. We studied the incidence of immediate contact reactions (wheal and flare) to the European standard series allergens in 664 patients. Patch tests were first examined at 30 min for immediate patch test (IPT) reactions, and again at D2 and D4 for delayed patch test (DPT) reactions. Almost all the allergens of the European standard series caused IPT reactions. IPT reactions were most commonl s compared to patients with (-) IPT reactions (fragrance compounds p<0.001, formaldehyde p<0.005,thiuram mix p<0.01, paraben mix p<0.05). Thus, perhaps the mechanisms involved in IPT reactions are not the same for all substances. At least for certain substances, an IPT reaction may be related to the development of a DPT reaction.","Frequency of immediate reactions to the European standard series Abs: BIOSIS COPYRIGHT: BIOL ABS. Immediate contact reactions (contact urticaria) can occur after skin contact with a wide range of substances. We studied the incidence of immediate contact reactions (wheal and flare) to the European standard series allergens in 664 patients. Patch tests were first examined at 30 min for immediate patch test (IPT) reactions, and again at D2 and D4 for delayed patch test (DPT) reactions. Almost all the allergens of the European standard series caused IPT reactions. IPT reactions were most commonl s compared to patients with (-) IPT reactions (fragrance compounds p<0.001, formaldehyde p<0.005,thiuram mix p<0.01, paraben mix p<0.05). Thus, perhaps the mechanisms involved in IPT reactions are not the same for all substances. At least for certain substances, an IPT reaction may be related to the development of a DPT reaction."
1236854,Maouad et al. 1999,Significance-prevalence index number: A reinterpretation and enhancement of data from the North American Contact Dermatitis Group,"BIOSIS COPYRIGHT: BIOL ABS. Background: The North American Contact Dermatitis Group (NACDG) periodically reports allergen reaction rates and clinical significance. These results are not formally interpreted combining both components into one index. Objective: The purpose of this study is to introduce the Significance-Prevalence Index Number (SPIN), which is a parameter that assesses the relative importance of different allergens. Methods: Data was collected from published studies reported by NACDG from 1984 through 1996. T llergens in clinical importance as measured by SPIN. Our SPIN calculations suggest that ethylenediamine and benzocaine have markedly decreased in clinical importance over the past decade, whereas methylchloroisothiazolinone/methylisothiazolinone has become a leading allergen. A number of allergens demonstrate high to intermediate SPIN, yet are not included in the T.R.U.E. test. These clinically important allergens include bacitracin, diazolidinyl urea, glyceryl thioglycate, ethyleneurea melamine","Significance-prevalence index number: A reinterpretation and enhancement of data from the North American Contact Dermatitis Group Abs: BIOSIS COPYRIGHT: BIOL ABS. Background: The North American Contact Dermatitis Group (NACDG) periodically reports allergen reaction rates and clinical significance. These results are not formally interpreted combining both components into one index. Objective: The purpose of this study is to introduce the Significance-Prevalence Index Number (SPIN), which is a parameter that assesses the relative importance of different allergens. Methods: Data was collected from published studies reported by NACDG from 1984 through 1996. T llergens in clinical importance as measured by SPIN. Our SPIN calculations suggest that ethylenediamine and benzocaine have markedly decreased in clinical importance over the past decade, whereas methylchloroisothiazolinone/methylisothiazolinone has become a leading allergen. A number of allergens demonstrate high to intermediate SPIN, yet are not included in the T.R.U.E. test. These clinically important allergens include bacitracin, diazolidinyl urea, glyceryl thioglycate, ethyleneurea melamine"
1236852,Dearman et al. 1999,Local lymph node assay: Use in hazard and risk assessment,"BIOSIS COPYRIGHT: BIOL ABS. The murine local lymph node assay (LLNA) was developed as an alternative method for the identification of chemicals that have the ability to cause skin sensitization and allergic contact dermatitis. The assay now has been evaluated extensively in the context of both national and international inter-laboratory collaborative trials and has been the subject of detailed comparisons with guinea pig test methods and human skin sensitization data. On the basis of these evaluations the LLNA has been end welfare; compared with guinea pig tests, fewer animals are required and these animals are subject to less trauma. It is important now that the validation status of the LLNA is recognized and the method applied widely so that these advantages may be realized. Hazard identification represents only the first step in the risk assessment process. A full toxicological evaluation of skin sensitization activity requires an understanding of relative potency. Guinea pig methods do not lend themselves rea sidered also. Finally, the current regulatory status of the LLNA is summarized and the application of the method for the purposes of defining relative potency and developing risk assessments is reviewed.","Local lymph node assay: Use in hazard and risk assessment Abs: BIOSIS COPYRIGHT: BIOL ABS. The murine local lymph node assay (LLNA) was developed as an alternative method for the identification of chemicals that have the ability to cause skin sensitization and allergic contact dermatitis. The assay now has been evaluated extensively in the context of both national and international inter-laboratory collaborative trials and has been the subject of detailed comparisons with guinea pig test methods and human skin sensitization data. On the basis of these evaluations the LLNA has been end welfare; compared with guinea pig tests, fewer animals are required and these animals are subject to less trauma. It is important now that the validation status of the LLNA is recognized and the method applied widely so that these advantages may be realized. Hazard identification represents only the first step in the risk assessment process. A full toxicological evaluation of skin sensitization activity requires an understanding of relative potency. Guinea pig methods do not lend themselves rea sidered also. Finally, the current regulatory status of the LLNA is summarized and the application of the method for the purposes of defining relative potency and developing risk assessments is reviewed."
1236823,Wahlberg 1965,"Percutaneous absorption of sodium chromate (51Cr), cobaltous (58Co), and mercuric (203Hg) chlorides through excised human and guinea pig skin",,"Percutaneous absorption of sodium chromate (51Cr), cobaltous (58Co), and mercuric (203Hg) chlorides through excised human and guinea pig skin Abs: "
1236817,Pham-Huu-Chanh 1965,"The comparative toxicity of sodium chromate, molybdate, tungstate and metavanadate: I. Experiments on mice and rats",,"The comparative toxicity of sodium chromate, molybdate, tungstate and metavanadate: I. Experiments on mice and rats Abs: "
1236708,Wahlberg 1968,"The effect of anionic, cationic, and nonionic detergents on the percutaneous absorption of sodium chromate (51Cr) in the guinea pig",,"The effect of anionic, cationic, and nonionic detergents on the percutaneous absorption of sodium chromate (51Cr) in the guinea pig Abs: "
1236613,Samitz 1970,Ascorbic acid in the prevention and treatment of toxic effects from chromates,"Ascorbic-acid is found to be effective in preventing and treating adverse reaction to chromates by inactivation of hexavalent chromium through reduction to trivalent chromium and subsequent complex formation of the trivalent species of chromium compounds. Ascorbic-acid is found to prevent acute systemic chromate intoxication when administered promptly to abrasions poisoned with potassium-chromate, to protect chromate sensitive workers from skin sensitization or allergic eczematous dermatitis from printing inks, to protect against chromic-acid mists (using ascorbic-acid impregnated filter masks), and to shorten the time of healing of skin ulcers experimentally produced by potassium-chromate.","Ascorbic acid in the prevention and treatment of toxic effects from chromates Abs: Ascorbic-acid is found to be effective in preventing and treating adverse reaction to chromates by inactivation of hexavalent chromium through reduction to trivalent chromium and subsequent complex formation of the trivalent species of chromium compounds. Ascorbic-acid is found to prevent acute systemic chromate intoxication when administered promptly to abrasions poisoned with potassium-chromate, to protect chromate sensitive workers from skin sensitization or allergic eczematous dermatitis from printing inks, to protect against chromic-acid mists (using ascorbic-acid impregnated filter masks), and to shorten the time of healing of skin ulcers experimentally produced by potassium-chromate."
1236589,Holdstock et al. 1970,Propulsion (mass movements) in the human colon and its relationship to meals and somatic activity,"Propulsive activity of the human colon was measured with radiopaque markers (shapes), radiotelemetering capsules, Perspex capsules containing (51)Cr, or with free (51)Cr sodium chromate. Propulsive activity can be readily detected by these techniques, none of which requires the use of radiological contrast media. With capsules containing (51)Cr or with free (51)Cr repeated observations can be made in the same patient without recourse to radiography. The patient can remain normally active during the test with encapsulated (51)Cr. Repeated observations may also be made with shapes, if films exposed at low mA are used. It was found that colonic intraluminal pressure activity rises markedly during and after food, but that in the resting patient this increase is rarely associated with propulsive activity. In physically active patients propulsion of colonic contents was significantly increased after meals. When colonic propulsion takes place, it does so by a series of mass movements. These results suggest that somatic activity is an important factor in the control of colonic transit in health or disease.","Propulsion (mass movements) in the human colon and its relationship to meals and somatic activity Abs: Propulsive activity of the human colon was measured with radiopaque markers (shapes), radiotelemetering capsules, Perspex capsules containing (51)Cr, or with free (51)Cr sodium chromate. Propulsive activity can be readily detected by these techniques, none of which requires the use of radiological contrast media. With capsules containing (51)Cr or with free (51)Cr repeated observations can be made in the same patient without recourse to radiography. The patient can remain normally active during the test with encapsulated (51)Cr. Repeated observations may also be made with shapes, if films exposed at low mA are used. It was found that colonic intraluminal pressure activity rises markedly during and after food, but that in the resting patient this increase is rarely associated with propulsive activity. In physically active patients propulsion of colonic contents was significantly increased after meals. When colonic propulsion takes place, it does so by a series of mass movements. These results suggest that somatic activity is an important factor in the control of colonic transit in health or disease."
1236580,Van Gent 1970,The determination of alcohol in blood by the South African modified Kozelka-Hine method: blood alcohol level as legal evidence,"HEEP COPYRIGHT: BIOL ABS. Several particulars must be carefully examined before the accuracy of a blood alcohol value, presented as legal evidence in a court of law, can be acknowledged. During and after its extraction from the arm of the person whose blood alcohol value is sought, the blood sample can undergo changes which might affect its content of volatile reducing agents and so produce a wrong value. In this method the blood sample is steam distilled after acidification and precipitation of proteins. The steam distillate is treated with Nessler's solution to remove aldehydes and ketones and reduce acids, after which it is distilled. The distillate is treated with a known quantity of acid potassium dichromate of which a portion is now reduced by the reducing agents in the distillate. The remaining portion of acid potassium dichromate is determined by titration. This portion, subtracted from the known quantity of acid potassium dichromate, gives the reduced portion from which the reducing agent (in many instances alcohol only) can now be calculated.","The determination of alcohol in blood by the South African modified Kozelka-Hine method: blood alcohol level as legal evidence Abs: HEEP COPYRIGHT: BIOL ABS. Several particulars must be carefully examined before the accuracy of a blood alcohol value, presented as legal evidence in a court of law, can be acknowledged. During and after its extraction from the arm of the person whose blood alcohol value is sought, the blood sample can undergo changes which might affect its content of volatile reducing agents and so produce a wrong value. In this method the blood sample is steam distilled after acidification and precipitation of proteins. The steam distillate is treated with Nessler's solution to remove aldehydes and ketones and reduce acids, after which it is distilled. The distillate is treated with a known quantity of acid potassium dichromate of which a portion is now reduced by the reducing agents in the distillate. The remaining portion of acid potassium dichromate is determined by titration. This portion, subtracted from the known quantity of acid potassium dichromate, gives the reduced portion from which the reducing agent (in many instances alcohol only) can now be calculated."
1236579,Calnan et al. 1970,Hand dermatitis in housewives,"Patch tests were conducted on 1,000 patients in an effort to study hand dermatitis in housewives. All patients worked exclusively in the home. Most were women, but some retired and unemployed men were included. Standard patch tests were conducted and 281 women diagnosed as having dermatitis of the hands. The responsible allergins in ranking order were: balsams, 27 percent; nickel (7440020), 14 percent; medications, 10 percent; cobalt (7440484), 8 percent; rubber, 7 percent; chromate (7778509), 5 percent; benzocaine (94097), 5 percent; and p-phenylene-diamine (106503), 5 percent. Of the housewives with dermatitis, 78 percent were diagnosed as having contact dermatitis, 5 percent atopic, 3 percent stasis, 1 percent nummular, and 13 percent unclassified dermatitis. The authors conclude that dermatitis of the hands may be due to the wet nature of domestic work. Allergens are more likely to induce sensitivity when applied to skin which has been immersed in water and shows hydration of the horny layer.","Hand dermatitis in housewives Abs: Patch tests were conducted on 1,000 patients in an effort to study hand dermatitis in housewives. All patients worked exclusively in the home. Most were women, but some retired and unemployed men were included. Standard patch tests were conducted and 281 women diagnosed as having dermatitis of the hands. The responsible allergins in ranking order were: balsams, 27 percent; nickel (7440020), 14 percent; medications, 10 percent; cobalt (7440484), 8 percent; rubber, 7 percent; chromate (7778509), 5 percent; benzocaine (94097), 5 percent; and p-phenylene-diamine (106503), 5 percent. Of the housewives with dermatitis, 78 percent were diagnosed as having contact dermatitis, 5 percent atopic, 3 percent stasis, 1 percent nummular, and 13 percent unclassified dermatitis. The authors conclude that dermatitis of the hands may be due to the wet nature of domestic work. Allergens are more likely to induce sensitivity when applied to skin which has been immersed in water and shows hydration of the horny layer."
1236544,Wiernikowski et al. 1971,[Case of acute potassium bichromate poisoning with acute renal failure treated with peritoneal dialysis],"HEEP COPYRIGHT: BIOL ABS. Case history of a female adolescent who attempted suicide by means of ingestion of potassium bichromate with her food was presented. Violent gastro-intestinal reaction took place within 15 min. and continued for some time. On the 4th day, symptoms of renal insufficiency developed. Peritoneal dialysis treatment was then initiated to deal with both the renal-urinary aspects of the patient's condition and to effect removal of the chrome compound. Employment of this method should begin immediately after diagnosis.","[Case of acute potassium bichromate poisoning with acute renal failure treated with peritoneal dialysis] Abs: HEEP COPYRIGHT: BIOL ABS. Case history of a female adolescent who attempted suicide by means of ingestion of potassium bichromate with her food was presented. Violent gastro-intestinal reaction took place within 15 min. and continued for some time. On the 4th day, symptoms of renal insufficiency developed. Peritoneal dialysis treatment was then initiated to deal with both the renal-urinary aspects of the patient's condition and to effect removal of the chrome compound. Employment of this method should begin immediately after diagnosis."
1236543,Feuerman 1971,Chromates as the cause of contact dermatitis in housewives,"HEEP COPYRIGHT: BIOL ABS. This study showed that 229 (91.6 percent) of 250 patients with housewives' eczema tested positive or strongly positive to a patch test with potassium dichromate. The possible relationship between this finding and the use of detergents was investigated by making a quantitative determination of the chromate content of 14 detergents widely used in Israel. A method found to give very reliable results was used for this purpose (full details are presented). All the detergents tested contained chromates in varying amounts, with the largest amounts present in bleaching solutions. The relatively high incidence chromate sensitivity among women with housewives' eczema living in this region is related to the photosensitizing properties of chromates.","Chromates as the cause of contact dermatitis in housewives Abs: HEEP COPYRIGHT: BIOL ABS. This study showed that 229 (91.6 percent) of 250 patients with housewives' eczema tested positive or strongly positive to a patch test with potassium dichromate. The possible relationship between this finding and the use of detergents was investigated by making a quantitative determination of the chromate content of 14 detergents widely used in Israel. A method found to give very reliable results was used for this purpose (full details are presented). All the detergents tested contained chromates in varying amounts, with the largest amounts present in bleaching solutions. The relatively high incidence chromate sensitivity among women with housewives' eczema living in this region is related to the photosensitizing properties of chromates."
1236526,Oleffe et al. 1971,[The presence of chrome in the occupational environment. Its retroaction on the repair of dermatoses],"HEEP COPYRIGHT: BIOL ABS. The Cr content of 59 products was determined. Of these, 80% of the results were positive; 28% were lower than 0.1 ppm (normal concentration of Cr in the blood of normal subjects). Since the Cr ion can be found in all occupations, the value of the patch test with potassium bichromate and the sensitivity limit value were discussed. When a diagnosis of occupational allergy to Cr is suspected, a clinical and occupational study should be made along with patch tests.","[The presence of chrome in the occupational environment. Its retroaction on the repair of dermatoses] Abs: HEEP COPYRIGHT: BIOL ABS. The Cr content of 59 products was determined. Of these, 80% of the results were positive; 28% were lower than 0.1 ppm (normal concentration of Cr in the blood of normal subjects). Since the Cr ion can be found in all occupations, the value of the patch test with potassium bichromate and the sensitivity limit value were discussed. When a diagnosis of occupational allergy to Cr is suspected, a clinical and occupational study should be made along with patch tests."
1236509,Heading et al. 1971,An evaluation of indium DTPA chelate in the measurement of gastric emptying by scintiscanning,"The sequential scintiscanning technique was used to determine gastric emptying rates in adult human subjects after ingestion of a meal of cornflakes and milk to which a gamma-emitting radioactive isotope had been added.Comparison of emptying rates using (113m)In DTPA chelate and (51)Cr sodium chromate showed that significantly slower rates were recorded with chromate, and studies in vitro demonstrated adsorption of chromate to the solid component of the meal. The results imply that the liquid phase of the gastric contents after a meal is discharged through the pylorus more rapidly than the solid phase. Scintiscanning with indium chelate provides a measurement of the emptying of the liquid phase of the gastric contents.","An evaluation of indium DTPA chelate in the measurement of gastric emptying by scintiscanning Abs: The sequential scintiscanning technique was used to determine gastric emptying rates in adult human subjects after ingestion of a meal of cornflakes and milk to which a gamma-emitting radioactive isotope had been added.Comparison of emptying rates using (113m)In DTPA chelate and (51)Cr sodium chromate showed that significantly slower rates were recorded with chromate, and studies in vitro demonstrated adsorption of chromate to the solid component of the meal. The results imply that the liquid phase of the gastric contents after a meal is discharged through the pylorus more rapidly than the solid phase. Scintiscanning with indium chelate provides a measurement of the emptying of the liquid phase of the gastric contents."
1236498,Hoye et al. 1971,Purity control of sodium chromate- 51 Cr by separation on a kieselguhr column,,Purity control of sodium chromate- 51 Cr by separation on a kieselguhr column Abs: 
1236473,Kanan 1972,Cement dermatitis and atmospheric parameters in Kuwait,"HEEP COPYRIGHT: BIOL ABS. A series of 191 male patients, 2 Kuwaitis and 189 non-Kuwaiti immigrants from the Middle East, with cement dermatitis, is reported. On the first visit 108 patients had already passed into the chronic stage and 40 percent showed an irregular nummular pattern. On patch testing, all 191 patients reacted positively to 0.5 percent potassium dichromate but only 13 of them reacted to 5 percent cobalt chloride, which incriminated the chromates as the significant allergen in cement dermatitis in Kuwait. Of the 191 patients, only 16 had suffered from transient dermatitis in their countries of origin. Seventy-seven of the remaining 175 patients came in contact with cement for the 1st time in Kuwait, whereas the other 88 patients had never had dermatitis in their countries of origin, in spite of long contact with cement. Of 112 patients who were followed up to a period longer than 2 yr, 84 (75 percent) were observed to have clinical exacerbation between Apr. and mid-Nov. each year. The curve describing the latter was a direct function of the curve obtained for the temperature monthly means. The rising humidity during Sept. each year overtook the high temperature, which probably provoked excessive perspiration and thus favored the leaching of chromate ions by the integument.","Cement dermatitis and atmospheric parameters in Kuwait Abs: HEEP COPYRIGHT: BIOL ABS. A series of 191 male patients, 2 Kuwaitis and 189 non-Kuwaiti immigrants from the Middle East, with cement dermatitis, is reported. On the first visit 108 patients had already passed into the chronic stage and 40 percent showed an irregular nummular pattern. On patch testing, all 191 patients reacted positively to 0.5 percent potassium dichromate but only 13 of them reacted to 5 percent cobalt chloride, which incriminated the chromates as the significant allergen in cement dermatitis in Kuwait. Of the 191 patients, only 16 had suffered from transient dermatitis in their countries of origin. Seventy-seven of the remaining 175 patients came in contact with cement for the 1st time in Kuwait, whereas the other 88 patients had never had dermatitis in their countries of origin, in spite of long contact with cement. Of 112 patients who were followed up to a period longer than 2 yr, 84 (75 percent) were observed to have clinical exacerbation between Apr. and mid-Nov. each year. The curve describing the latter was a direct function of the curve obtained for the temperature monthly means. The rising humidity during Sept. each year overtook the high temperature, which probably provoked excessive perspiration and thus favored the leaching of chromate ions by the integument."
1236455,Clark and  Kunitsch 1972,[Statistical studies of cross allergy in metal salts],"HEEP COPYRIGHT: BIOL ABS. Length of occupation and age were studied in 500 subjects allergic to metal salts and hospitalized from 1956 to 1963 at Hannover, W. Germany. Whether cross allergies occur with certain metal salts (potassium dichromate, chromium-(III)-chloride, nickel sulfate, Hg (sublimate), Hg (precipitate), cobalt-(II)-chloride was determined. Age was related to significant differences in the moment at which maximum morbidity was reached. No cross allergy could be found. Statistical study of the occurrence of allergies to 2 metal salts revealed a postive correlation in 8 out of 11 pairs of metal salts, but does not prove that cross allergy is the cause. In double allergies, an enlargement of the allergic spectrum must be reckoned with. Allergies appear more often in elderly persons, and are often present even in pensioned people. The influence exerted by profession on appearance of allergy to metal salts could be confirmed in 99.0% of the cases. Specifically increased allergization by specific metal salts was not revealed in occupational specialities.","[Statistical studies of cross allergy in metal salts] Abs: HEEP COPYRIGHT: BIOL ABS. Length of occupation and age were studied in 500 subjects allergic to metal salts and hospitalized from 1956 to 1963 at Hannover, W. Germany. Whether cross allergies occur with certain metal salts (potassium dichromate, chromium-(III)-chloride, nickel sulfate, Hg (sublimate), Hg (precipitate), cobalt-(II)-chloride was determined. Age was related to significant differences in the moment at which maximum morbidity was reached. No cross allergy could be found. Statistical study of the occurrence of allergies to 2 metal salts revealed a postive correlation in 8 out of 11 pairs of metal salts, but does not prove that cross allergy is the cause. In double allergies, an enlargement of the allergic spectrum must be reckoned with. Allergies appear more often in elderly persons, and are often present even in pensioned people. The influence exerted by profession on appearance of allergy to metal salts could be confirmed in 99.0% of the cases. Specifically increased allergization by specific metal salts was not revealed in occupational specialities."
1236454,Fregert and  Gruvberger 1972,Chemical properties of cement,"HEEP COPYRIGHT: BIOL ABS. The amount of Cr present in cement is related to the development of cement eczema. In building work, contact with wet cement cannot be avoided. The possibility of decreasing the development of cement eczema by minimizing the amount of hexavalent Cr present was examined. The chemical properties of cement were investigated. Cr, Co and Ni contents were determined by atomic absorption which makes determination possible in an alkaline environment and also differentiates between tri- and hexa-valent Cr. Samples (52) of cement from 9 countries contained 1-40 mug Cr/g in water soluble form. By extraction with sodium sulfate, higher values were obtained (1-83 mug Cr/g) in all but 1 sample. In all samples total content was higher than in those obtained by sulfate extraction (35-173 mug Cr/g). Co and Ni were not present in water soluble formt The total contents were 17-63 mug Co/g and 32-116 mug Ni/g, respectively. The alkalinity (OH--) was, in all 52 samples, 13-79 mmoles/1 and varied within the same factory during a 3 wk period. A correlation between water-soluble hexa-valent Cr and total Cr was not found. Two samples had considerably higher total Cr contents than all the others, yet had water-soluble Cr values that were among the lowest. Certain chemical factors in cement might regulate that part of the total that becomes water-soluble.","Chemical properties of cement Abs: HEEP COPYRIGHT: BIOL ABS. The amount of Cr present in cement is related to the development of cement eczema. In building work, contact with wet cement cannot be avoided. The possibility of decreasing the development of cement eczema by minimizing the amount of hexavalent Cr present was examined. The chemical properties of cement were investigated. Cr, Co and Ni contents were determined by atomic absorption which makes determination possible in an alkaline environment and also differentiates between tri- and hexa-valent Cr. Samples (52) of cement from 9 countries contained 1-40 mug Cr/g in water soluble form. By extraction with sodium sulfate, higher values were obtained (1-83 mug Cr/g) in all but 1 sample. In all samples total content was higher than in those obtained by sulfate extraction (35-173 mug Cr/g). Co and Ni were not present in water soluble formt The total contents were 17-63 mug Co/g and 32-116 mug Ni/g, respectively. The alkalinity (OH--) was, in all 52 samples, 13-79 mmoles/1 and varied within the same factory during a 3 wk period. A correlation between water-soluble hexa-valent Cr and total Cr was not found. Two samples had considerably higher total Cr contents than all the others, yet had water-soluble Cr values that were among the lowest. Certain chemical factors in cement might regulate that part of the total that becomes water-soluble."
1236446,Feuerman 1972,Studies on contact dermatitis in housewives,"HEEP COPYRIGHT: BIOL ABS. A high number of positive patch tests with potassium dichromate was found in housewives with contact dermatitis. Patch tests with other substances were positive in a much smaller numer of patients. Chemical examination of a large number of detergents widely used in Israel showed that they all contained chromate. In a further study of this problem, a comparative study was made of the effectiveness of an anionic-exchanger for chrome ointment in cases of housewives' eczema. The anionic-exchanger ointment gave very good protection. Another standard silicone-containing ointment had a poor protective effect. These results confirmed those from previous studies and implicated chromates as the main factors causing allergic contact dermatitis in housewives' in Israel.","Studies on contact dermatitis in housewives Abs: HEEP COPYRIGHT: BIOL ABS. A high number of positive patch tests with potassium dichromate was found in housewives with contact dermatitis. Patch tests with other substances were positive in a much smaller numer of patients. Chemical examination of a large number of detergents widely used in Israel showed that they all contained chromate. In a further study of this problem, a comparative study was made of the effectiveness of an anionic-exchanger for chrome ointment in cases of housewives' eczema. The anionic-exchanger ointment gave very good protection. Another standard silicone-containing ointment had a poor protective effect. These results confirmed those from previous studies and implicated chromates as the main factors causing allergic contact dermatitis in housewives' in Israel."
1236441,García-Pérez et al. 1973,Chrome content in bleaches and detergents. Its relationship to hand dermatitis in women,"HEEP COPYRIGHT: BIOL ABS. From 1967-1972 the frequency of eczemas in women with a positive chrome patch-test has decreased strikingly in Salamanca (Spain), in comparison with the 1963-66 period. In a 1963 study 7 out of 9 brand bleaches and 1 out of 3 liquid detergents in domestic use, selected from those most commonly used in this area, contained chromate. In 1972 only 2 out of 9 bleaches contained it. The chromate was not present as impurities, but rather as a component of the product, being added during the manufacturing process in the form of potassium bichromate. Bleaches and liquid detergents containing chromate have been one of the most frequent causes of ""housewive's dermatitis"" in the Salamanca area.","Chrome content in bleaches and detergents. Its relationship to hand dermatitis in women Abs: HEEP COPYRIGHT: BIOL ABS. From 1967-1972 the frequency of eczemas in women with a positive chrome patch-test has decreased strikingly in Salamanca (Spain), in comparison with the 1963-66 period. In a 1963 study 7 out of 9 brand bleaches and 1 out of 3 liquid detergents in domestic use, selected from those most commonly used in this area, contained chromate. In 1972 only 2 out of 9 bleaches contained it. The chromate was not present as impurities, but rather as a component of the product, being added during the manufacturing process in the form of potassium bichromate. Bleaches and liquid detergents containing chromate have been one of the most frequent causes of ""housewive's dermatitis"" in the Salamanca area."
1236434,Schlatter and  Kissling 1973,[Acute fatal bichromate poisoning],"HEEP COPYRIGHT: BIOL ABS. A rare case of intoxication, lethal 70 h after swallowing less than 3 g potassium bichromate showed a typical history beginning with vomiting and diarrhea. A drop in blood pressure followed and later there was hemorrhagic diathesis, increased liver enzymes, anuria and death in coma. The amount of Cr in the blood was about 1500, in the liver, kidney and adrenal medulla about 4500-5500 mug/100 g. The spleen contained 1350, other organs between 300 and 1000 and the brain about 80-100 mug/100 g. Only 10% of the estimated remaining Cr (about 200-500 mg) could be removed by hemodialysis.","[Acute fatal bichromate poisoning] Abs: HEEP COPYRIGHT: BIOL ABS. A rare case of intoxication, lethal 70 h after swallowing less than 3 g potassium bichromate showed a typical history beginning with vomiting and diarrhea. A drop in blood pressure followed and later there was hemorrhagic diathesis, increased liver enzymes, anuria and death in coma. The amount of Cr in the blood was about 1500, in the liver, kidney and adrenal medulla about 4500-5500 mug/100 g. The spleen contained 1350, other organs between 300 and 1000 and the brain about 80-100 mug/100 g. Only 10% of the estimated remaining Cr (about 200-500 mg) could be removed by hemodialysis."
1236417,Baer et al. 1973,The most common contact allergens 1968-1970,"HEEP COPYRIGHT: BIOL ABS. The 24 contact allergens are presented which produced positive patch test reactions in 3% or more of the patient population of the New York University Skin and Cancer Unit (USA) between 1968-1970. The 10 most common among these were mercury bichloride, mercaptobenzothiazole, paraphenylene-diamine, potassium dichromate, ethylenediamine, nickel sulfate, turpentine oil, formaldehyde solution, poison ivy and bismarck brown. Some of the sources of exposure to these allergens and some of the known corss-sensitizing compounds are listed. The clinical significance strong vs. weak patch test reactions is discussed.","The most common contact allergens 1968-1970 Abs: HEEP COPYRIGHT: BIOL ABS. The 24 contact allergens are presented which produced positive patch test reactions in 3% or more of the patient population of the New York University Skin and Cancer Unit (USA) between 1968-1970. The 10 most common among these were mercury bichloride, mercaptobenzothiazole, paraphenylene-diamine, potassium dichromate, ethylenediamine, nickel sulfate, turpentine oil, formaldehyde solution, poison ivy and bismarck brown. Some of the sources of exposure to these allergens and some of the known corss-sensitizing compounds are listed. The clinical significance strong vs. weak patch test reactions is discussed."
1236405,Karim 1973,Preparation of sodium chromate-51Cr and chromic chloride-51Cr for medical applications,,Preparation of sodium chromate-51Cr and chromic chloride-51Cr for medical applications Abs: 
1236380,Jones and  Poulsen 1974,Abomasal emptying rate in goats and cows measured by external counting of radioactive sodium chromate injected directly into the abomasum,,Abomasal emptying rate in goats and cows measured by external counting of radioactive sodium chromate injected directly into the abomasum Abs: 
1236330,Smith et al. 1975,Platelet kinetics in canine ehrlichiosis: evidence for increased platelet destruction as the cause of thrombocytopenia,"A significant (P &lt; 0.025) increase in the mean platelet diameter occurred in five Ehrlichia canis-infected dogs when platelet numbers decreased to 100,000/mul or less. Maximal incorporation of [(75)Se]selenomethionine into platelets of six uninfected dogs was 0.080 +/- 0.019% (mean +/- standard error) and occurred 5 to 6 days after dosage, whereas maximal incorporation was 0.036 +/- 0.004% within 2 to 3 days after dosage in seven chronically infected dogs that had thrombocytopenia. Analysis of the [(75)Se]selenomethionine curves yielded a platelet lifespan of 9 days in uninfected dogs versus 4 days in chronically infected dogs. Thus, megakaryocyte maturation and/or platelet release occurred at an accelerated rate in infected dogs, whereas increased destruction of newly produced labeled platelets diminished their number of peripheral blood. [(51)Cr]sodium chromate-labeled platelet survival was exponential, with a half-life of approximately 1 day in two dogs at 2 to 4 days postinfection and three chronically infected dogs. Platelet survival time was 8 days and rectilinear in four uninfected dogs. Platelet recovery was 39.43 +/- 2.86% in infected dogs as compared with 68.2 +/- 10.72% in uninfected dogs. Whole-body scans of one dog prior to and 7 days after infection showed that labeled platelets were destroyed primarily in the spleen. It is concluded that the thrombocytopenia in E. canis-infected dogs is the result of increased platelet destruction which begins within a few days after infection.","Platelet kinetics in canine ehrlichiosis: evidence for increased platelet destruction as the cause of thrombocytopenia Abs: A significant (P &lt; 0.025) increase in the mean platelet diameter occurred in five Ehrlichia canis-infected dogs when platelet numbers decreased to 100,000/mul or less. Maximal incorporation of [(75)Se]selenomethionine into platelets of six uninfected dogs was 0.080 +/- 0.019% (mean +/- standard error) and occurred 5 to 6 days after dosage, whereas maximal incorporation was 0.036 +/- 0.004% within 2 to 3 days after dosage in seven chronically infected dogs that had thrombocytopenia. Analysis of the [(75)Se]selenomethionine curves yielded a platelet lifespan of 9 days in uninfected dogs versus 4 days in chronically infected dogs. Thus, megakaryocyte maturation and/or platelet release occurred at an accelerated rate in infected dogs, whereas increased destruction of newly produced labeled platelets diminished their number of peripheral blood. [(51)Cr]sodium chromate-labeled platelet survival was exponential, with a half-life of approximately 1 day in two dogs at 2 to 4 days postinfection and three chronically infected dogs. Platelet survival time was 8 days and rectilinear in four uninfected dogs. Platelet recovery was 39.43 +/- 2.86% in infected dogs as compared with 68.2 +/- 10.72% in uninfected dogs. Whole-body scans of one dog prior to and 7 days after infection showed that labeled platelets were destroyed primarily in the spleen. It is concluded that the thrombocytopenia in E. canis-infected dogs is the result of increased platelet destruction which begins within a few days after infection."
1236326,Kutti and  Safai-Kutti 1975,In vitro labelling of platelets: an experimental study on healthy asplenic subjects using two different incubation media,"Duplicate platelet survival studies, using autologous platelets labelled in vitro with radioactive sodium chromate, were performed on six young healthy asplenic men. In the first experiment plasma, and in the second a Ringer-citrate-dextrose (RCD) solution (Abrahamsen, 1968), was employed as incubation medium. The uptake of chromate by the platelets was about 2.5 times higher in the RCD compared to the plasma experiments. An identical pattern for the immediate behaviour of infused labelled platelets was observed in the duplicate studies, and the recovery of platelet-bound radioactivity remained stable at the 90% level during 2 h post-infusion. In these experiments the means for platelet mean life span (MLS) were identical, 7.2 +/- 0.5 and 7.2 +/- 0.4 days, respectively. These values slightly, but not significantly, exceeded the mean platelet MLS for a control group consisting of 10 young healthy males (6.9 +/- 0.4 days). The means for platelet production rate (P) at the duplicate studies made on the asplenic subjects were 19 +/- 2 X 10(10) and 21 +/- 2 X 10(10) platelets per day, respectively, and did not differ from the mean for P obtained in the control group (22 +/- 2 X 10(10).","In vitro labelling of platelets: an experimental study on healthy asplenic subjects using two different incubation media Abs: Duplicate platelet survival studies, using autologous platelets labelled in vitro with radioactive sodium chromate, were performed on six young healthy asplenic men. In the first experiment plasma, and in the second a Ringer-citrate-dextrose (RCD) solution (Abrahamsen, 1968), was employed as incubation medium. The uptake of chromate by the platelets was about 2.5 times higher in the RCD compared to the plasma experiments. An identical pattern for the immediate behaviour of infused labelled platelets was observed in the duplicate studies, and the recovery of platelet-bound radioactivity remained stable at the 90% level during 2 h post-infusion. In these experiments the means for platelet mean life span (MLS) were identical, 7.2 +/- 0.5 and 7.2 +/- 0.4 days, respectively. These values slightly, but not significantly, exceeded the mean platelet MLS for a control group consisting of 10 young healthy males (6.9 +/- 0.4 days). The means for platelet production rate (P) at the duplicate studies made on the asplenic subjects were 19 +/- 2 X 10(10) and 21 +/- 2 X 10(10) platelets per day, respectively, and did not differ from the mean for P obtained in the control group (22 +/- 2 X 10(10)."
1236312,Tovar et al. 1976,Endotoxin clearance after intralipid infusion,"Healthy 6-8-wk-old New Zealand white rabbits were injected with chromium-chloride- or sodium-chromate-labeled E. coli endotoxin after rapid infusion (10 ml/kg in 1 hr) or slow and repeated infusions (40 ml/kg daily for 7 consecutive days) of 10% Intralipid. Endotoxin clearance rates and RES organ uptakes were determined and the results were compared with those of the controls treated with correspondingly equal volumes of 5% D/W instead of fat. In the acute experiment, the clearance rates were similar in all animals during the first 15 min following endotoxin injection. After this phase, however, experimental animals had faster endotoxin clearance and eventually higher organ uptakes than the controls. In the chronic experiment, there was no significant difference in endotoxin clearance rates or total and per-gram organ uptakes between experimental and corresponding control animals infused with 5% D/W instead of fat. Experimental animals, particularly those having received multiple infusions of fat emulsion, showed deposition of polarizable brown pigment inside and outside the reticuloendothelial cells in the liver, spleen, and bone marrow. None of the controls had these pigments in their organs.","Endotoxin clearance after intralipid infusion Abs: Healthy 6-8-wk-old New Zealand white rabbits were injected with chromium-chloride- or sodium-chromate-labeled E. coli endotoxin after rapid infusion (10 ml/kg in 1 hr) or slow and repeated infusions (40 ml/kg daily for 7 consecutive days) of 10% Intralipid. Endotoxin clearance rates and RES organ uptakes were determined and the results were compared with those of the controls treated with correspondingly equal volumes of 5% D/W instead of fat. In the acute experiment, the clearance rates were similar in all animals during the first 15 min following endotoxin injection. After this phase, however, experimental animals had faster endotoxin clearance and eventually higher organ uptakes than the controls. In the chronic experiment, there was no significant difference in endotoxin clearance rates or total and per-gram organ uptakes between experimental and corresponding control animals infused with 5% D/W instead of fat. Experimental animals, particularly those having received multiple infusions of fat emulsion, showed deposition of polarizable brown pigment inside and outside the reticuloendothelial cells in the liver, spleen, and bone marrow. None of the controls had these pigments in their organs."
1236311,Zemliano? et al. 1976,[Radioisotope method of diagnosis of internal hemorrhage],The authors have developed experimentally and employed clinically a new method of diagnosing a localization of the source of intermittent internal hemorrhage. The method consists in determination of blood congestion sites by radioactive changes measured by external recordings after injection of 2.5 muc per Kg weight of radioactive chromium-51 in sodium chromate in the circulating blood.,[Radioisotope method of diagnosis of internal hemorrhage] Abs: The authors have developed experimentally and employed clinically a new method of diagnosing a localization of the source of intermittent internal hemorrhage. The method consists in determination of blood congestion sites by radioactive changes measured by external recordings after injection of 2.5 muc per Kg weight of radioactive chromium-51 in sodium chromate in the circulating blood.
1236307,Berggard 1976,"beta2-Microglobulins: isolation, properties, and distribution","beta2-Microglobulin is structurally related to immunoglobulin domains and is identical to the light chain of histocompatibility (HL-A) antigens. Similar to free light chains of immunoglobulins, beta2-microglobulin is most easily isolated from urine. We have previously purified human beta2-microglobulin from urine of patients with renal tubular resorption defects. Corresponding proteins have now been obtained from urine of rabbits and guinea pigs treated with sodium chromate. Sequence studies have established that the rabbit protein is rabbit beta2-microglobulin. The guinea pig protein closely resembles the human and rabbit beta2-microglobulins in amino acid composition, charge, molecular size, and also in the presence of an apparently analogous disulfide loop. These findings indicate that this protein is the guinea pig homologue of beta2-microglobulin. Physical-chemical studies suggest that human beta2-microglobulin and isolated immunoglobulin domains are similar not only in amino acid sequence but also in three-dimensional structure. Both types of molecules are compact and globular in shape and apparently contain beta-pleated sheet conformation. beta2-Microglobulin is present in free form in various body fluids and as a subunit of histocompatibility antigens on cell surfaces. Current estimates suggest that the number of beta2-microglobulin molecules on cell surfaces is higher than the number of histocompatibility (HL-A) antigens. Accordingly, beta2-microglobulin is possibly a subunit of additional cellular antigens or receptors.","beta2-Microglobulins: isolation, properties, and distribution Abs: beta2-Microglobulin is structurally related to immunoglobulin domains and is identical to the light chain of histocompatibility (HL-A) antigens. Similar to free light chains of immunoglobulins, beta2-microglobulin is most easily isolated from urine. We have previously purified human beta2-microglobulin from urine of patients with renal tubular resorption defects. Corresponding proteins have now been obtained from urine of rabbits and guinea pigs treated with sodium chromate. Sequence studies have established that the rabbit protein is rabbit beta2-microglobulin. The guinea pig protein closely resembles the human and rabbit beta2-microglobulins in amino acid composition, charge, molecular size, and also in the presence of an apparently analogous disulfide loop. These findings indicate that this protein is the guinea pig homologue of beta2-microglobulin. Physical-chemical studies suggest that human beta2-microglobulin and isolated immunoglobulin domains are similar not only in amino acid sequence but also in three-dimensional structure. Both types of molecules are compact and globular in shape and apparently contain beta-pleated sheet conformation. beta2-Microglobulin is present in free form in various body fluids and as a subunit of histocompatibility antigens on cell surfaces. Current estimates suggest that the number of beta2-microglobulin molecules on cell surfaces is higher than the number of histocompatibility (HL-A) antigens. Accordingly, beta2-microglobulin is possibly a subunit of additional cellular antigens or receptors."
1236306,Munro-Ashman and  Miller 1976,Rejection of metal to metal prosthesis and skin sensitivity to cobalt,"Metal to metal prostheses give satisfactory results in 90% of patients. About half of the failure rate may be due to allergic reaction to the metals involved, particularly cobalt. A total of 35 patients in this unsatisfactory group have been patch-tested; 16 were positive to metals, 13 to cobalt, 4 to nickel, and 2 to chromate. Only two patients showed any skin lesions - one a localized dermatitis round the knee joint from nickel sensitivity, and one to cobalt who had a widespread scattered circular erythematous lesion suggestive of a generalized allergic vasculitis. Patients requiring a metal/metal prosthesis should have a careful history taken for metal sensitivity and be patch-tested with the metals. All the patients in this investigation had metal/metal prostheses and no reaction was seen after metal/high density polyethylene implants. Titanium 318 may be a satisfactory substitute for cobalt chrome alloy if reactions are encountered.","Rejection of metal to metal prosthesis and skin sensitivity to cobalt Abs: Metal to metal prostheses give satisfactory results in 90% of patients. About half of the failure rate may be due to allergic reaction to the metals involved, particularly cobalt. A total of 35 patients in this unsatisfactory group have been patch-tested; 16 were positive to metals, 13 to cobalt, 4 to nickel, and 2 to chromate. Only two patients showed any skin lesions - one a localized dermatitis round the knee joint from nickel sensitivity, and one to cobalt who had a widespread scattered circular erythematous lesion suggestive of a generalized allergic vasculitis. Patients requiring a metal/metal prosthesis should have a careful history taken for metal sensitivity and be patch-tested with the metals. All the patients in this investigation had metal/metal prostheses and no reaction was seen after metal/high density polyethylene implants. Titanium 318 may be a satisfactory substitute for cobalt chrome alloy if reactions are encountered."
1236305,Skrabut et al. 1976,(51CR) sodium chromate incorporation ito the soluble protein fractin of the human erythrocyte: binding not associated with the hemoglobin monomeric subunit,,(51CR) sodium chromate incorporation ito the soluble protein fractin of the human erythrocyte: binding not associated with the hemoglobin monomeric subunit Abs: 
1236302,Hurwitz et al. 1976,Effects of antacids on gastric emptying,"Aluminum hydroxide gel delays gastric emptying in rats and man. This effect of aluminum hydroxide gel varies with the concentration of aluminum in solution in the stomach when pH, osmolarity, and anion content are held constant. Because aluminum solubility drops as pH is raised, those antacids which neutralize more effectively than aluminum hydroxide gel alone and which contain &quot;nonreactive&quot; aluminum hydroxide result in lower aluminum concentration and do not affect the rate of gastric emptying in animals or in man. By using [51Cr]sodium chromate and a gamma camera technique, half-emptying time in 6 subjects with no gastrointestinal disease was shown to be prolonged from 13.1 min after water ingestion to 48.0 min after three hourly doses of aluminum hydroxide gel. Conventional nonabsorbable markers, including phenol red, were found to be of limited use for studying gastrointestinal function in the presence of antacid gels, most of which adsorb dyes.","Effects of antacids on gastric emptying Abs: Aluminum hydroxide gel delays gastric emptying in rats and man. This effect of aluminum hydroxide gel varies with the concentration of aluminum in solution in the stomach when pH, osmolarity, and anion content are held constant. Because aluminum solubility drops as pH is raised, those antacids which neutralize more effectively than aluminum hydroxide gel alone and which contain &quot;nonreactive&quot; aluminum hydroxide result in lower aluminum concentration and do not affect the rate of gastric emptying in animals or in man. By using [51Cr]sodium chromate and a gamma camera technique, half-emptying time in 6 subjects with no gastrointestinal disease was shown to be prolonged from 13.1 min after water ingestion to 48.0 min after three hourly doses of aluminum hydroxide gel. Conventional nonabsorbable markers, including phenol red, were found to be of limited use for studying gastrointestinal function in the presence of antacid gels, most of which adsorb dyes."
1236299,Adams et al. 1976,Water solubility of zinc chromate primer paints used as antirust agents,,Water solubility of zinc chromate primer paints used as antirust agents Abs: 
1236295,Olsson et al. 1977,In vitro labelling of platelets. Experimental study on splenectomized patients with lymphomas using two different incubation media,"Duplicate platelet survival studies, using autologous platelets labelled in vitro with radioactive sodium chromate, were carried out on 5 lymphoma patients who had been splenectomized 14-21 months earlier. In the first experiment plasma was employed as the incubation medium and in the second a Ringer-citrate-dextrose (RCD) solution. The uptake of chromate by the platelets was 2.0 times higher in the RCD as compared to the plasma experiments. An identical pattern for the immediate behaviour of infused labelled platelets was observed in the duplicate studies, and the recovery of platelet-bound radioactivity remained stable at the 90% level during 2 h after infusion. In these experiments the means for platelet mean life span were almost identical, 5.4+/-0.6 and 5.3+/-0.5 days, respectively, and significantly (p less than 0.05) shorter than the mean for a control group consisting of 21 healthy males (6.9+/-0.3 days). It is concluded that RCD and plasma seem to serve equally well as incubation medium at the in vitro labelling of platelets.","In vitro labelling of platelets. Experimental study on splenectomized patients with lymphomas using two different incubation media Abs: Duplicate platelet survival studies, using autologous platelets labelled in vitro with radioactive sodium chromate, were carried out on 5 lymphoma patients who had been splenectomized 14-21 months earlier. In the first experiment plasma was employed as the incubation medium and in the second a Ringer-citrate-dextrose (RCD) solution. The uptake of chromate by the platelets was 2.0 times higher in the RCD as compared to the plasma experiments. An identical pattern for the immediate behaviour of infused labelled platelets was observed in the duplicate studies, and the recovery of platelet-bound radioactivity remained stable at the 90% level during 2 h after infusion. In these experiments the means for platelet mean life span were almost identical, 5.4+/-0.6 and 5.3+/-0.5 days, respectively, and significantly (p less than 0.05) shorter than the mean for a control group consisting of 21 healthy males (6.9+/-0.3 days). It is concluded that RCD and plasma seem to serve equally well as incubation medium at the in vitro labelling of platelets."
1236293,Buchanan et al. 1977,Use of homologous platelet survival in differential diagnoses of chronic thrombocytopenia in childhood,"Twenty-one children with chronic thrombocytopenia of obscure etiology, 19 of whom had normal numbers of bone marrow megakaryocytes, were evaluated in order to determine if factors extrinsic to the platelets themselves (presumably antibodies) caused the thrombocytopenia. The rapid destruction of platelets by such antibodies has been demonstrated to cause idiopathic thrombocytopenic purpura (ITP). History, physical examination, and routine laboratory studies were unable to provide an exact diagnosis in these patients. Measurement of platelet survival, using sodium chromate Cr 51 labeled homologous platelets obtained from unrelated donors, permitted a clear separation of these children into two groups. One group (11 patients) had a markedly shortened platelet life span, and was considered to have chronic ITP. The other group (10 patients) had a normal or only slightly reduced platelet life span. Thus, the destruction of platelets by extrinsic factors could be ruled out. Since the diagnosis of chronic ITP was excluded, splenectomy could be avoided in these patients since it is rarely useful in children with nonimmune forms of chronic thrombocytopenia. Homologous platelet survival measurement is a useful diagnostic tool in certain children with chronic thrombocytopenia.","Use of homologous platelet survival in differential diagnoses of chronic thrombocytopenia in childhood Abs: Twenty-one children with chronic thrombocytopenia of obscure etiology, 19 of whom had normal numbers of bone marrow megakaryocytes, were evaluated in order to determine if factors extrinsic to the platelets themselves (presumably antibodies) caused the thrombocytopenia. The rapid destruction of platelets by such antibodies has been demonstrated to cause idiopathic thrombocytopenic purpura (ITP). History, physical examination, and routine laboratory studies were unable to provide an exact diagnosis in these patients. Measurement of platelet survival, using sodium chromate Cr 51 labeled homologous platelets obtained from unrelated donors, permitted a clear separation of these children into two groups. One group (11 patients) had a markedly shortened platelet life span, and was considered to have chronic ITP. The other group (10 patients) had a normal or only slightly reduced platelet life span. Thus, the destruction of platelets by extrinsic factors could be ruled out. Since the diagnosis of chronic ITP was excluded, splenectomy could be avoided in these patients since it is rarely useful in children with nonimmune forms of chronic thrombocytopenia. Homologous platelet survival measurement is a useful diagnostic tool in certain children with chronic thrombocytopenia."
1236291,Norman-Taylor 1977,The importance of an occupational history: an illustrative example,"An illustrative case is presented of a patient with a blood stained discharge from his nose, an ulcerating lesion on his nasal septum, who came to an eye, nose and throat clinic. An occupational history of the patient indicated a six-week work spell in a dusty factory where he works with 'sulfur' with or without a mask. On the basis of the results of biopsy and other tests, radiotherapy was started, but later discontinued in order to study the patient's working conditions. The source of the sulfur was the hexavalent sodium-bichromate (10588019) in the mix used for manufacturing chrome (7440473) pigments, chrome-oxide (1308389) and chrome-hydroxide (1308141), which are green pigments in paint. The case illustrates the need for accurate checking of occupational history with, if necessary, the consulting physician getting first hand information from the factory medical adviser, and the importance of the worker being informed of the right names of the substances with which he works.","The importance of an occupational history: an illustrative example Abs: An illustrative case is presented of a patient with a blood stained discharge from his nose, an ulcerating lesion on his nasal septum, who came to an eye, nose and throat clinic. An occupational history of the patient indicated a six-week work spell in a dusty factory where he works with 'sulfur' with or without a mask. On the basis of the results of biopsy and other tests, radiotherapy was started, but later discontinued in order to study the patient's working conditions. The source of the sulfur was the hexavalent sodium-bichromate (10588019) in the mix used for manufacturing chrome (7440473) pigments, chrome-oxide (1308389) and chrome-hydroxide (1308141), which are green pigments in paint. The case illustrates the need for accurate checking of occupational history with, if necessary, the consulting physician getting first hand information from the factory medical adviser, and the importance of the worker being informed of the right names of the substances with which he works."
1236287,Elboim et al. 1977,T and B lymphocyte migration into syngeneic tumors,"The migration of splenic T and B lymphocytes into syngeneic tumors undergoing immunologic rejection was investigates. Spleen cells were obtained from normal BALC/c mice or BALB/c mice bearing tumors induced by murine sarcoma virus (MSV). Either whole spleen cells or immunoabsorbent purified T and B cells were radiolabeled with sodium chromate-51 and injected i.v. into normal or MSV inducted-tumor bearing syngeneic recipients. Twenty-four hours later the recipient mice were sacrificed and radioactivity was assessed for tumor, contralateral normal muscle, the lymph nodes draining the tumor and contralateral draining lymph nodes, peripheral lymph nodes, spleen, and liver. Both T and B lymphocytes from either normal or MSV tumor-bearing animals show greatly increased migration into the tumor when compared with normal muscle. Migration of T cells from both normal and MSV tumor bearers was 30 times that of migration to normal muscle. B cells from tumor-bearing mice, on the other hand, localized in the tumor itself only 50% as frequently as did B cells from normal animals. In addition, T cells from MSV tumor bearers were found in the highest proportion in the lymph node draining the tumor site. We conclude that T and B lymphocytes from either normal or tumor-bearing mice migrate to a syngeneic tumor undergoing immunologic rejection. In contrast, the migration of both T and B cells from tumor-bearing animals was decreased to the peripheral lymph nodes at the time of maximum tumor growth.","T and B lymphocyte migration into syngeneic tumors Abs: The migration of splenic T and B lymphocytes into syngeneic tumors undergoing immunologic rejection was investigates. Spleen cells were obtained from normal BALC/c mice or BALB/c mice bearing tumors induced by murine sarcoma virus (MSV). Either whole spleen cells or immunoabsorbent purified T and B cells were radiolabeled with sodium chromate-51 and injected i.v. into normal or MSV inducted-tumor bearing syngeneic recipients. Twenty-four hours later the recipient mice were sacrificed and radioactivity was assessed for tumor, contralateral normal muscle, the lymph nodes draining the tumor and contralateral draining lymph nodes, peripheral lymph nodes, spleen, and liver. Both T and B lymphocytes from either normal or MSV tumor-bearing animals show greatly increased migration into the tumor when compared with normal muscle. Migration of T cells from both normal and MSV tumor bearers was 30 times that of migration to normal muscle. B cells from tumor-bearing mice, on the other hand, localized in the tumor itself only 50% as frequently as did B cells from normal animals. In addition, T cells from MSV tumor bearers were found in the highest proportion in the lymph node draining the tumor site. We conclude that T and B lymphocytes from either normal or tumor-bearing mice migrate to a syngeneic tumor undergoing immunologic rejection. In contrast, the migration of both T and B cells from tumor-bearing animals was decreased to the peripheral lymph nodes at the time of maximum tumor growth."
1236283,Dvorak et al. 1977,Host-defense mechanisms in hidradenitis suppurativa,"Host-defense mechanisms were studied in seven patients with active hidradenitis suppurativa (HS). Granulocyte phagocytic function was measured by ingestion of Staphylococcus aureus labeled with radioactive carbon 14 and intracellular killing was determined by bactericidal pour plate method. Chemotaxis was measured by radioactive counting of sodium chromate Cr 51 granulocytes migrating in modified Boyden chambers. Granulocyte adherence was estimated in vitro by filtering blood samples through nylon fiber columns. Cell-mediated immunity was measured by intradermal delayed hypersensitivity responses to Candida, mumps. streptokinase/streptodornase, and purified protein derivative antigens. No abnormality was demonstrated in any granulocyte or cell-mediated immune function tests. Moreover, all patients had normal immunoglobulin levels and elevated total hemolytic complement. Therefore, we conclude that HS is a localized chronic infection of apocrine glands without a generalized defect in host defense.","Host-defense mechanisms in hidradenitis suppurativa Abs: Host-defense mechanisms were studied in seven patients with active hidradenitis suppurativa (HS). Granulocyte phagocytic function was measured by ingestion of Staphylococcus aureus labeled with radioactive carbon 14 and intracellular killing was determined by bactericidal pour plate method. Chemotaxis was measured by radioactive counting of sodium chromate Cr 51 granulocytes migrating in modified Boyden chambers. Granulocyte adherence was estimated in vitro by filtering blood samples through nylon fiber columns. Cell-mediated immunity was measured by intradermal delayed hypersensitivity responses to Candida, mumps. streptokinase/streptodornase, and purified protein derivative antigens. No abnormality was demonstrated in any granulocyte or cell-mediated immune function tests. Moreover, all patients had normal immunoglobulin levels and elevated total hemolytic complement. Therefore, we conclude that HS is a localized chronic infection of apocrine glands without a generalized defect in host defense."
1236277,Draggan 1977,Interactive effect of chromium compounds and a fungal parasite on carp eggs,A fungal parasite (Saprolegniales) of carp eggs was exposed to hexavalent and trivalent chromium compounds at concentrations identical to those used in a study of the effects of the same compounds on carp eggs hatchability. Comparison of data from both experiments revealed that increased egg mortality and increased fungal growth were cooupled at low concentrations of the compounds. A mechanism for the interaction of a chemical stress and a biological stress on carp egg survival in natural systems is presented.,Interactive effect of chromium compounds and a fungal parasite on carp eggs Abs: A fungal parasite (Saprolegniales) of carp eggs was exposed to hexavalent and trivalent chromium compounds at concentrations identical to those used in a study of the effects of the same compounds on carp eggs hatchability. Comparison of data from both experiments revealed that increased egg mortality and increased fungal growth were cooupled at low concentrations of the compounds. A mechanism for the interaction of a chemical stress and a biological stress on carp egg survival in natural systems is presented.
1236273,Rycroft and  Calnan 1977,Chromate dermatitis from a boiler lining,"Chromate dermatitis is described in a mechanical fitter working inside boiler combustion chambers. A source of hexavalent chromate is traced to the action of the heat and alkaline fuel ash on trivalent chrome ore in parts of the refractory lining. Removal of the patient from this contact has resulted in almost complete clearing of his dermatitis, without any relapse, during a 9-month follow-up period.","Chromate dermatitis from a boiler lining Abs: Chromate dermatitis is described in a mechanical fitter working inside boiler combustion chambers. A source of hexavalent chromate is traced to the action of the heat and alkaline fuel ash on trivalent chrome ore in parts of the refractory lining. Removal of the patient from this contact has resulted in almost complete clearing of his dermatitis, without any relapse, during a 9-month follow-up period."
1236264,Rannie and  Donald 1977,"Estimation of the migration of thoracic duct lymphocytes to non-lymphoid tissues. A comparison of the distribution of radioactivity at intervals following i.v. transfusion of cells labelled with 3H, 14C, 75Se, 99mTc, 125I and 51Cr in the rat","The distribution of radioisotopes in tissues was measured following i.v. injection of labelled thoracic duct lymphocytes into syngeneic rats. The rate of elution of an isotope from the labelled cells and the subsequent fate of the eluted isotope were shown to be the most important factors limiting the usefulness of such isotopes for measuring cell localization particularly in non-lymphoid tissues. Comparison of labelling procedures using [3H] and [14C]uridine, [3H] and [14C]leucine, [75Se]-L-selenomethionine, [99mTc]sodium pertechnetate and [51Cr]sodium chromate in vitro and [3H]thymidine in vivo showed that 51Cr had the fewest disadvantages in the present context. Using 51Cr-labelled cells, the radioactivity was measured in a wide range of non-lymphoid tissues, and estimates of cell traffic were obtained. In skin, for example, the results indicate a cell flux in the range of 10(4)-10(5) lymphocytes/gm/hr. Evidence is presented which suggests that the early substantial localization of labelled cells in the lung is not an artefact due to sequestration or embolization of traumatized cells but probably reflects a slow intravascular transit time through this capillary bed. The primary lymphoid organs, thymus and bone marrow were shown to include a subpopulation of lymphocytes which belong to the recirculating pool. The thymus always contained a greater concentration of radioactivity at 24 hr than all non-lymphoid tissues except liver and kidney (approx. 0-1% of the recirculating lymphocyte pool) and the bone marrow was capable of temporarily accepting a substantial proportion (approx.25%) of the injected cells.","Estimation of the migration of thoracic duct lymphocytes to non-lymphoid tissues. A comparison of the distribution of radioactivity at intervals following i.v. transfusion of cells labelled with 3H, 14C, 75Se, 99mTc, 125I and 51Cr in the rat Abs: The distribution of radioisotopes in tissues was measured following i.v. injection of labelled thoracic duct lymphocytes into syngeneic rats. The rate of elution of an isotope from the labelled cells and the subsequent fate of the eluted isotope were shown to be the most important factors limiting the usefulness of such isotopes for measuring cell localization particularly in non-lymphoid tissues. Comparison of labelling procedures using [3H] and [14C]uridine, [3H] and [14C]leucine, [75Se]-L-selenomethionine, [99mTc]sodium pertechnetate and [51Cr]sodium chromate in vitro and [3H]thymidine in vivo showed that 51Cr had the fewest disadvantages in the present context. Using 51Cr-labelled cells, the radioactivity was measured in a wide range of non-lymphoid tissues, and estimates of cell traffic were obtained. In skin, for example, the results indicate a cell flux in the range of 10(4)-10(5) lymphocytes/gm/hr. Evidence is presented which suggests that the early substantial localization of labelled cells in the lung is not an artefact due to sequestration or embolization of traumatized cells but probably reflects a slow intravascular transit time through this capillary bed. The primary lymphoid organs, thymus and bone marrow were shown to include a subpopulation of lymphocytes which belong to the recirculating pool. The thymus always contained a greater concentration of radioactivity at 24 hr than all non-lymphoid tissues except liver and kidney (approx. 0-1% of the recirculating lymphocyte pool) and the bone marrow was capable of temporarily accepting a substantial proportion (approx.25%) of the injected cells."
1236262,Skinner et al. 1978,Splenic foci of cytotoxic lymphocytes in a graft-versus-host reaction,"It has been established that cytotoxic lymphocytes are generated in discrete foci in the spleens of mice undergoing a graft-versus-host reaction. The foci segregated randomly in such spleens. 2.8 X 10(4) lymph node cells, 2.3 X 10(5) spleen cells and 2.7 X 10(6) thymus cells from CBA mice generated a mean of one focus in lethally irradiated (CBA X DBA)F1 recipient mice. Cytotoxic foci were detected when cytotoxicity was measured by two different cytotoxicity assays, the release of [51Cr]-sodium chromate from [51Cr]-labelled target cells and colony inhibition. The seeding efficiency of cytotoxic focus-forming cells has been estimated at 19%.","Splenic foci of cytotoxic lymphocytes in a graft-versus-host reaction Abs: It has been established that cytotoxic lymphocytes are generated in discrete foci in the spleens of mice undergoing a graft-versus-host reaction. The foci segregated randomly in such spleens. 2.8 X 10(4) lymph node cells, 2.3 X 10(5) spleen cells and 2.7 X 10(6) thymus cells from CBA mice generated a mean of one focus in lethally irradiated (CBA X DBA)F1 recipient mice. Cytotoxic foci were detected when cytotoxicity was measured by two different cytotoxicity assays, the release of [51Cr]-sodium chromate from [51Cr]-labelled target cells and colony inhibition. The seeding efficiency of cytotoxic focus-forming cells has been estimated at 19%."
1236260,Stevenson et al. 1978,beta2-Microglobulin from normal and leukaemic guinea-pig lymphocytes,"beta2-Microglobulin has been isolated in useful quantities from the urine of strain-2 guinea-pigs after either treatment with sodium chromate or induction of the L2C leukaemia. Antibodies raised against the beta2-microglobulin were used to set up a radioimmunoassay which measured its export into culture fluid by normal and leukaemic lymphocytes. Material containing beta2-microglobulin was also obtained by digestion of the lymphocytic surfaces with papain; fractionation demonstrated both free and combined forms, with no qualitative difference between those from normal and those from leukaemic cells.","beta2-Microglobulin from normal and leukaemic guinea-pig lymphocytes Abs: beta2-Microglobulin has been isolated in useful quantities from the urine of strain-2 guinea-pigs after either treatment with sodium chromate or induction of the L2C leukaemia. Antibodies raised against the beta2-microglobulin were used to set up a radioimmunoassay which measured its export into culture fluid by normal and leukaemic lymphocytes. Material containing beta2-microglobulin was also obtained by digestion of the lymphocytic surfaces with papain; fractionation demonstrated both free and combined forms, with no qualitative difference between those from normal and those from leukaemic cells."
1236254,Mayron and  Kaplan 1978,The use of chromium-51 sodium chromate for the detection of food and chemical sensitivities,"Both antibody mediated lysis of human RBC's and toxic hemolysis were found to occur with chemicals used as coloring agents for foods, drugs and cosmetics. Because of the strong chromaticity of these dyes, chromium-51 sodium chromate was bound to the hemoglobin of target human RBC's and its efflux was used as an indicator of lysis instead of spectrophotometry, which had been used with food antigens. The major antibody effect was noted when treatment of the target RBC's with antiIgG resulted in a marked inhibition of lysis, indicating that IgG is a lysis-promoting factor (LPF) in this system. Weaker effects were noted by treatment of the target RBC's with monospecific antisera for the other four classes of immunoglobulin and for alpha2-macroglobulin. No neutralizing effects were observed by pre-incubation of the dyes with autologous serum prior to the addition of RBC's.","The use of chromium-51 sodium chromate for the detection of food and chemical sensitivities Abs: Both antibody mediated lysis of human RBC's and toxic hemolysis were found to occur with chemicals used as coloring agents for foods, drugs and cosmetics. Because of the strong chromaticity of these dyes, chromium-51 sodium chromate was bound to the hemoglobin of target human RBC's and its efflux was used as an indicator of lysis instead of spectrophotometry, which had been used with food antigens. The major antibody effect was noted when treatment of the target RBC's with antiIgG resulted in a marked inhibition of lysis, indicating that IgG is a lysis-promoting factor (LPF) in this system. Weaker effects were noted by treatment of the target RBC's with monospecific antisera for the other four classes of immunoglobulin and for alpha2-macroglobulin. No neutralizing effects were observed by pre-incubation of the dyes with autologous serum prior to the addition of RBC's."
1236247,Fredén et al. 1978,The exchangeable splenic platelet pool in response to intravenous infusion of isoprenaline,"8 healthy volunteers and 4 asplenic subjects, in whom autologous platelets had been labelled with radioactive sodium chromate, received i.v. infusions of isoprenaline in a dose of 0.03 microgram x kg-1 x min-1 over a period of 6 min. In the former group these infusions caused a significant decrease in the concentration of labelled as well as unlabelled platelets in the peripheral blood. Body surface countings showed that a significant increase in the count rate over the spleen occurred concomitantly with the decrease in the circulating platelet-bound radioactivity (PBR). In the group of asplenic subjects no change in PBR occurred. It is concluded that adrenergic beta-receptor stimulation causes a transitory trapping of platelets in the exchangeable splenic platelet pool.","The exchangeable splenic platelet pool in response to intravenous infusion of isoprenaline Abs: 8 healthy volunteers and 4 asplenic subjects, in whom autologous platelets had been labelled with radioactive sodium chromate, received i.v. infusions of isoprenaline in a dose of 0.03 microgram x kg-1 x min-1 over a period of 6 min. In the former group these infusions caused a significant decrease in the concentration of labelled as well as unlabelled platelets in the peripheral blood. Body surface countings showed that a significant increase in the count rate over the spleen occurred concomitantly with the decrease in the circulating platelet-bound radioactivity (PBR). In the group of asplenic subjects no change in PBR occurred. It is concluded that adrenergic beta-receptor stimulation causes a transitory trapping of platelets in the exchangeable splenic platelet pool."
1236245,Law et al. 1978,Case report: familial thrombo-cytopenia in seven members of three generations,"All members in one generation and two of six members of the next generation were found to have familial thrombocytopenia. The disorder was transmitted as an autosomal dominant trait. Easy bruising and a bleeding tendency were the common features. No member had splenomegaly. Platelet counts varied from 8 to 75 x 10-9/liter, and there were no apparent morphologic abnormalities. Platelet survival studies using sodium chromate Cr 51-labeled autologous platelets were done for three members and showed shortened survival times. Two members were treated with corticosteroids and splenectomy without benefit. Three members tolerated surgery (splenectomy, polypectomy) without undue difficulty. Defective or ineffective thrombocytopoiesis appeared to be the basis of this hereditary disorder.","Case report: familial thrombo-cytopenia in seven members of three generations Abs: All members in one generation and two of six members of the next generation were found to have familial thrombocytopenia. The disorder was transmitted as an autosomal dominant trait. Easy bruising and a bleeding tendency were the common features. No member had splenomegaly. Platelet counts varied from 8 to 75 x 10-9/liter, and there were no apparent morphologic abnormalities. Platelet survival studies using sodium chromate Cr 51-labeled autologous platelets were done for three members and showed shortened survival times. Two members were treated with corticosteroids and splenectomy without benefit. Three members tolerated surgery (splenectomy, polypectomy) without undue difficulty. Defective or ineffective thrombocytopoiesis appeared to be the basis of this hereditary disorder."
1236243,Schick and  Berke 1978,Is the presence of serologically defined target cell antigens sufficient for binding of cytotoxic T lymphocytes?,"Target cell parameters that coincide with specific binding (conjugation) of target cells to cytotoxic T lymphocytes were examined. It was demonstrated that concentrations of formaldehyde (0 to 1.2%) which do not affect the capacity of target cells to exclude dyes and incorporate sodium chromate, or their susceptibility to cellular and humoral immune lysis did not affect target cell conjugation. Treatments with higher formaldehyde concentrations (1.6 to 3.2%) caused similar decreases in all of the above-mentioned target cell parameters. Formaldehyde-treated (over 0.1%) targets that could not cap alloantigens or incorporate macromolecular precursors could still conjugate with cytotoxic T lymphocytes. Quantitative changes of serologically detected antigens alone cannot account for the decrease in binding of formaldehyde (greater than 1.2%)-treated target cells to cytotoxic T lymphocytes, since absorption of lytic alloantibodies by formaldehyde-fixed targets was not affected over the fixative range used (0 to 3.2%). From this study, it appears that certain target cell properties related to membrane structure and function and not the apparent expression of serologically defined antigens alone are essential for binding of targets by cytotoxic T lymphocytes. Additionally, it was shown that target cell susceptibility to immune lysis is retained, as long as their ability to bind to cytotoxic T lymphocytes is not affected.","Is the presence of serologically defined target cell antigens sufficient for binding of cytotoxic T lymphocytes? Abs: Target cell parameters that coincide with specific binding (conjugation) of target cells to cytotoxic T lymphocytes were examined. It was demonstrated that concentrations of formaldehyde (0 to 1.2%) which do not affect the capacity of target cells to exclude dyes and incorporate sodium chromate, or their susceptibility to cellular and humoral immune lysis did not affect target cell conjugation. Treatments with higher formaldehyde concentrations (1.6 to 3.2%) caused similar decreases in all of the above-mentioned target cell parameters. Formaldehyde-treated (over 0.1%) targets that could not cap alloantigens or incorporate macromolecular precursors could still conjugate with cytotoxic T lymphocytes. Quantitative changes of serologically detected antigens alone cannot account for the decrease in binding of formaldehyde (greater than 1.2%)-treated target cells to cytotoxic T lymphocytes, since absorption of lytic alloantibodies by formaldehyde-fixed targets was not affected over the fixative range used (0 to 3.2%). From this study, it appears that certain target cell properties related to membrane structure and function and not the apparent expression of serologically defined antigens alone are essential for binding of targets by cytotoxic T lymphocytes. Additionally, it was shown that target cell susceptibility to immune lysis is retained, as long as their ability to bind to cytotoxic T lymphocytes is not affected."
1236228,Pories et al. 1979,Mineral metabolism of the healing arterial wall,"The mineral metabolism of healing arterial walls was studied by measuring the accumulation of several radioisotopes at the site of vascular repair in rats. Each rat was subjected to a 1-cm full-thickness aortotomy and then immediately injected by tail vein with c 5 muCi of one of the following radioisotopes: chromic chloride Cr 51 or sodium chromate Cr 51; ferrous chloride Fe 59 or ferric chloride Fe 59; manganous chloride Mn 54; selenious acid Se 75; strontium chloride Sr 85; or zinc chloride Zn 65. At intervals of 1, 2, 4, 6, and 10 days after operation and injection, groups of four rats for each radioisotope were killed, aortas dissected, and the specific radioactivity of healing vascular tissue compared with that of adjacent normal artery. There were sharp and statistically significant differences in the preferential accumulation of the radioisotopes in healing compared with normal aorta. Zinc appeared to be the element most involved in vascular repair, followed by selenium and chromium.","Mineral metabolism of the healing arterial wall Abs: The mineral metabolism of healing arterial walls was studied by measuring the accumulation of several radioisotopes at the site of vascular repair in rats. Each rat was subjected to a 1-cm full-thickness aortotomy and then immediately injected by tail vein with c 5 muCi of one of the following radioisotopes: chromic chloride Cr 51 or sodium chromate Cr 51; ferrous chloride Fe 59 or ferric chloride Fe 59; manganous chloride Mn 54; selenious acid Se 75; strontium chloride Sr 85; or zinc chloride Zn 65. At intervals of 1, 2, 4, 6, and 10 days after operation and injection, groups of four rats for each radioisotope were killed, aortas dissected, and the specific radioactivity of healing vascular tissue compared with that of adjacent normal artery. There were sharp and statistically significant differences in the preferential accumulation of the radioisotopes in healing compared with normal aorta. Zinc appeared to be the element most involved in vascular repair, followed by selenium and chromium."
1236220,Algvere and  Bill 1979,Drainage of microspheres and RBCs from the vitreous of aphakic and phakic eyes,"The movements of plastic microspheres (7 to 10 mu in diameter) and autologous RBCs labeled with sodium chromate Cr 51 from the vitreous to the anterior chamber were studied in 24 rabbit eyes. Rabbits were made aphakic in one eye by intracapsular lens extraction of lensectomy via the pars plana, the fellow eyes serving as phakic controls. In phakic eyes the intravitreally injected microspheres and RBCs were retained inside the vitreous space, not gaining access to the anterior chamber. In aphakic eyes microspheres and RBCs moved to the anterior chamber and were usually seen on the corneal endothelium and in the chamber angle within two to ten days, although most particles remained in the vitreous for long periods of time. Removal of the lens thus improved forward drainage of particles from the vitreous space, but the structure of the vitreous seemed to preclude rapid clearance.","Drainage of microspheres and RBCs from the vitreous of aphakic and phakic eyes Abs: The movements of plastic microspheres (7 to 10 mu in diameter) and autologous RBCs labeled with sodium chromate Cr 51 from the vitreous to the anterior chamber were studied in 24 rabbit eyes. Rabbits were made aphakic in one eye by intracapsular lens extraction of lensectomy via the pars plana, the fellow eyes serving as phakic controls. In phakic eyes the intravitreally injected microspheres and RBCs were retained inside the vitreous space, not gaining access to the anterior chamber. In aphakic eyes microspheres and RBCs moved to the anterior chamber and were usually seen on the corneal endothelium and in the chamber angle within two to ten days, although most particles remained in the vitreous for long periods of time. Removal of the lens thus improved forward drainage of particles from the vitreous space, but the structure of the vitreous seemed to preclude rapid clearance."
1236215,Macrae et al. 1979,Sister chromatid exchanges induced in cultured mammalian cells by chromate,"Chromate compounds induced sister chromatoid exchanges (SCEs) and chromosome aberrations in cultured mammalian cells. Similar increases in SCE frequency were observed in human fibroblasts exposed to the compounds K2Cr2O7 and K2CrO4. Marked increases in SCE frequency in cells exposed to chromate for a 48-h period were detected at concentrations between 10(-7) and 10(-6) M. Chromosome aberrations (primarily chromatid breaks) were also produced in human cells exposed to K2CrO4 at concentrations between 8 . 10(-7) and 3 . 10(-6) M. K2CrO4, but not the trivalent compound CrCl3, induced SCEs in Chinese hamster ovary (CHO) cells at low concentrations.","Sister chromatid exchanges induced in cultured mammalian cells by chromate Abs: Chromate compounds induced sister chromatoid exchanges (SCEs) and chromosome aberrations in cultured mammalian cells. Similar increases in SCE frequency were observed in human fibroblasts exposed to the compounds K2Cr2O7 and K2CrO4. Marked increases in SCE frequency in cells exposed to chromate for a 48-h period were detected at concentrations between 10(-7) and 10(-6) M. Chromosome aberrations (primarily chromatid breaks) were also produced in human cells exposed to K2CrO4 at concentrations between 8 . 10(-7) and 3 . 10(-6) M. K2CrO4, but not the trivalent compound CrCl3, induced SCEs in Chinese hamster ovary (CHO) cells at low concentrations."
1236211,Reifenstein and  Pätzold 1980,[Elimination of chromate in cement],"HEEP COPYRIGHT: BIOL ABS. Laboratory tests were carried out to determine water-soluble Cr(IV) content of GDR (East Germany) brands of selected cement products of different origin and quality and possibilities of eliminating Cr(VI) content, which is harmful for human skin, by using Fe(II) salts were examined. Cr(VI) content of cements was between 0.4-20 ppm and Portland cement brands had a higher content than slag cement varieties. Added to cement or fresh concrete, iron (II) sulfate and ammonium iron(II) sulfate reduced water-soluble Cr(VI) to insoluble Cr(III), which precipitated as a hydroxide. Additions of 0.1-0.5% iron(II) sulfate by weight of the cement were sufficient to reduce water-soluble Cr(VI) content or eliminate it altogether. The possibility of using iron(II) sulfate in practical work and of combating cement eczema is discussed.","[Elimination of chromate in cement] Abs: HEEP COPYRIGHT: BIOL ABS. Laboratory tests were carried out to determine water-soluble Cr(IV) content of GDR (East Germany) brands of selected cement products of different origin and quality and possibilities of eliminating Cr(VI) content, which is harmful for human skin, by using Fe(II) salts were examined. Cr(VI) content of cements was between 0.4-20 ppm and Portland cement brands had a higher content than slag cement varieties. Added to cement or fresh concrete, iron (II) sulfate and ammonium iron(II) sulfate reduced water-soluble Cr(VI) to insoluble Cr(III), which precipitated as a hydroxide. Additions of 0.1-0.5% iron(II) sulfate by weight of the cement were sufficient to reduce water-soluble Cr(VI) content or eliminate it altogether. The possibility of using iron(II) sulfate in practical work and of combating cement eczema is discussed."
1236207,Sugatt 1980,"Effects of sublethal sodium dichromate exposure in freshwater on the salinity tolerance and serum osmolality of juvenile coho salmon, Oncorhynchus kisutch, in seawater","To stimulate a potential field situation in which seaward-migrating juvenile coho salmon, Oncorhynchus kisutch, pass through Cr-polluted freshwater (FW) before being exposed to seawater (SW), the effects of sublethal FW exposure to Cr (as sodium dichromate) on salinity tolerance and serum osmolality after transfer to SW were investigated. SW survival was significantly decreased in salmon exposed in FW to 0.23 mg Cr/L for four weeks or to 0.5 mg Cr/L for two weeks and transferred to 20 or 30 parts per thousand (%) salinity, respectively. Serum osmolality, measured after two weeks of FW exposure to 0.0 or 0.5 mg Cr/L and after transfer to 20 or 30% SW, was significantly higher in Cr-exposed fish from one-half to two days after SW transfer but not at the end of the FW exposure period or at seven days after SW transfer. These effects in SW occurred at Cr exposure concentrations which had no effect on survival or serum osmolality in FW. It is suggested that Cr acted non-specifically on osmoregulatory epithelia to cause excessive dehydration in SW, and that measurement of salinity tolerance and serum osmolality may be sensitive and ecologically realistic indicators of sublethal toxicity in aquatic animals.","Effects of sublethal sodium dichromate exposure in freshwater on the salinity tolerance and serum osmolality of juvenile coho salmon, Oncorhynchus kisutch, in seawater Abs: To stimulate a potential field situation in which seaward-migrating juvenile coho salmon, Oncorhynchus kisutch, pass through Cr-polluted freshwater (FW) before being exposed to seawater (SW), the effects of sublethal FW exposure to Cr (as sodium dichromate) on salinity tolerance and serum osmolality after transfer to SW were investigated. SW survival was significantly decreased in salmon exposed in FW to 0.23 mg Cr/L for four weeks or to 0.5 mg Cr/L for two weeks and transferred to 20 or 30 parts per thousand (%) salinity, respectively. Serum osmolality, measured after two weeks of FW exposure to 0.0 or 0.5 mg Cr/L and after transfer to 20 or 30% SW, was significantly higher in Cr-exposed fish from one-half to two days after SW transfer but not at the end of the FW exposure period or at seven days after SW transfer. These effects in SW occurred at Cr exposure concentrations which had no effect on survival or serum osmolality in FW. It is suggested that Cr acted non-specifically on osmoregulatory epithelia to cause excessive dehydration in SW, and that measurement of salinity tolerance and serum osmolality may be sensitive and ecologically realistic indicators of sublethal toxicity in aquatic animals."
1236200,Vilén et al. 1980,Presence of a non-splenic platelet pool in man,"3 asplenic but otherwise healthy men, in whom autologous platelets had been labelled with radioactive sodium chromate, received i.v. infusions of epinephrine in a dose of 0.35 micrograms per kg per min over a period of 20 min. In response to these infusions an increase in the concentration of labelled platelets (average 8% over the basal value) was seen in all 3 subjects. In no case was the maximal increase in the venous haematocrit higher than 1%. Identical experiments were also carried out on 3 intact male volunteers. As compared to the asplenics, the mean maximal increase in platelet-bound radioactivity was considerably higher (41%). It is concluded that a small but significant epinephrine sensitive non-splenic platelet pool is present in humans.","Presence of a non-splenic platelet pool in man Abs: 3 asplenic but otherwise healthy men, in whom autologous platelets had been labelled with radioactive sodium chromate, received i.v. infusions of epinephrine in a dose of 0.35 micrograms per kg per min over a period of 20 min. In response to these infusions an increase in the concentration of labelled platelets (average 8% over the basal value) was seen in all 3 subjects. In no case was the maximal increase in the venous haematocrit higher than 1%. Identical experiments were also carried out on 3 intact male volunteers. As compared to the asplenics, the mean maximal increase in platelet-bound radioactivity was considerably higher (41%). It is concluded that a small but significant epinephrine sensitive non-splenic platelet pool is present in humans."
1236183,Baranowska-Dutkiewicz 1981,Absorption of hexavalent chromium by skin in man,"Absorption by skin of hexavalent chromium from aqueous solutions of sodium chromate in man was investigated. It was found that the amount of chromium absorbed was related to the concentration of Cr6+ in solution and to time of exposure. For 0.01, 0.1, and 0.2 molar solutions of chromium, skin absorption rates during 1 h exposure were 1.1, 6.5, and 10.0 micrograms/cm2/h respectively.","Absorption of hexavalent chromium by skin in man Abs: Absorption by skin of hexavalent chromium from aqueous solutions of sodium chromate in man was investigated. It was found that the amount of chromium absorbed was related to the concentration of Cr6+ in solution and to time of exposure. For 0.01, 0.1, and 0.2 molar solutions of chromium, skin absorption rates during 1 h exposure were 1.1, 6.5, and 10.0 micrograms/cm2/h respectively."
1236167,Ornsholt et al. 1982,Recovery of gastric acid after vagotomy with and without a drainage,This study tests the possibility that the difference in acid reduction after parietal cell vagotomy (PCV) and selective gastric vagotomy with a drainage (SGV + D) could be explained by differences in the secretion recovered rather than by real secretory differences. A method for estimating the completeness of aspiration during gastric function tests using the isotope Na251CrO4 as an inert marker is described. The method was used in patients with the two types of vagotomy and the recovery of gastric secretion was more complete after PCV (89.7%) than after SGV + D (75.1%). This difference may substantially account for the apparent difference in reduction of acid secretion after the two operations. The pyloroplasty supplementing the SGV is probably responsible for a pyloric loss causing a lower recovery after this operation.,Recovery of gastric acid after vagotomy with and without a drainage Abs: This study tests the possibility that the difference in acid reduction after parietal cell vagotomy (PCV) and selective gastric vagotomy with a drainage (SGV + D) could be explained by differences in the secretion recovered rather than by real secretory differences. A method for estimating the completeness of aspiration during gastric function tests using the isotope Na251CrO4 as an inert marker is described. The method was used in patients with the two types of vagotomy and the recovery of gastric secretion was more complete after PCV (89.7%) than after SGV + D (75.1%). This difference may substantially account for the apparent difference in reduction of acid secretion after the two operations. The pyloroplasty supplementing the SGV is probably responsible for a pyloric loss causing a lower recovery after this operation.
1236164,Abe et al. 1982,Chromate lung cancer with special reference to its cell type and relation to the manufacturing process,"The manufacturing process of the chromate industry can be classified into five steps. The main hazardous pollutants of the first step are trivalent chromate compounds, and those of the second and third steps are hexavalent chromate compounds. Analysis of the detailed working history of chromate workers with bronchogenic carcinoma, yielded the following results: the work history of chromatic lung cancer patients in the first step, which produced mainly trivalent chromate dust, was rather short. Patients with small cell carcinoma were engaged mainly in the second step (98.1% of the total working months), where they were heavily exposed to hexavalent chromate dusts. Patients with squamous cell carcinoma were engaged rather evenly in the second and fourth steps, and somewhat longer in the third step. Comparisons of the exposure periods revealed that the working history of small cell carcinoma patients was significantly shorter than that of squamous cell carcinoma patients. There were many more heavy smokers among the squamous cell carcinoma group as compared to the small cell carcinoma patients. Based on these results, it is concluded that the cell type of occupational lung cancer was mainly small cell carcinoma when the exposure to carcinogenic agents was heavy, and that the carcinogenicity of chromate was derived mainly from hexavalent chromate rather than trivalent compounds.","Chromate lung cancer with special reference to its cell type and relation to the manufacturing process Abs: The manufacturing process of the chromate industry can be classified into five steps. The main hazardous pollutants of the first step are trivalent chromate compounds, and those of the second and third steps are hexavalent chromate compounds. Analysis of the detailed working history of chromate workers with bronchogenic carcinoma, yielded the following results: the work history of chromatic lung cancer patients in the first step, which produced mainly trivalent chromate dust, was rather short. Patients with small cell carcinoma were engaged mainly in the second step (98.1% of the total working months), where they were heavily exposed to hexavalent chromate dusts. Patients with squamous cell carcinoma were engaged rather evenly in the second and fourth steps, and somewhat longer in the third step. Comparisons of the exposure periods revealed that the working history of small cell carcinoma patients was significantly shorter than that of squamous cell carcinoma patients. There were many more heavy smokers among the squamous cell carcinoma group as compared to the small cell carcinoma patients. Based on these results, it is concluded that the cell type of occupational lung cancer was mainly small cell carcinoma when the exposure to carcinogenic agents was heavy, and that the carcinogenicity of chromate was derived mainly from hexavalent chromate rather than trivalent compounds."
1236160,Leonard et al. 1982,Chemical burns: effect of prompt first aid,"Chemical burns account for a relatively small proportion of the patients treated within a burn center; however, certain characteristics of these injuries, particularly in the initial stages of treatment, justify their separate consideration and review. Thirty-five patients were treated in the Baltimore Regional Burn Center from July 1976 through June 1980, with 14 different agents involved. The majority of injuries were work related; however, 20% were the result of assault. All patients received copious water lavage as primary therapy. In approximately one half of the patients this was begun as a first-aid measure at the scene of the accident. Compared to the group which did not receive lavage until admission to the hospital, the patients receiving appropriate first aid showed significantly less full-thickness injury and more than twofold shorter hospital stay, indicating the importance of public and industrial medical awareness of the role of immediate copious lavage. The problems of systemic toxicity with and specific therapy for certain agents is discussed with particular attention given to an unusual case involving cutaneous absorption of dichromate.","Chemical burns: effect of prompt first aid Abs: Chemical burns account for a relatively small proportion of the patients treated within a burn center; however, certain characteristics of these injuries, particularly in the initial stages of treatment, justify their separate consideration and review. Thirty-five patients were treated in the Baltimore Regional Burn Center from July 1976 through June 1980, with 14 different agents involved. The majority of injuries were work related; however, 20% were the result of assault. All patients received copious water lavage as primary therapy. In approximately one half of the patients this was begun as a first-aid measure at the scene of the accident. Compared to the group which did not receive lavage until admission to the hospital, the patients receiving appropriate first aid showed significantly less full-thickness injury and more than twofold shorter hospital stay, indicating the importance of public and industrial medical awareness of the role of immediate copious lavage. The problems of systemic toxicity with and specific therapy for certain agents is discussed with particular attention given to an unusual case involving cutaneous absorption of dichromate."
1236159,Ellis et al. 1982,Effects of hemodialysis and dimercaprol in acute dichromate poisoning,"A 22-month-old infant died after ingesting sodium dichromate his father had brought from work. Treatment included folic acid and dimercaprol administration, hemodialysis, and exchange transfusion. To evaluate this treatment, four dogs were hemodialyzed after receiving intravenous sodium dichromate: their dialyzer chromate clearance was similar to their renal chromate clearance and their dialyzer chromate clearance was not significantly different before or after dimercaprol administration. This and other cases in the literature indicate that although chromate poisoning is often fatal, supportive care, forced diuresis, and chelating agents may be helpful. Hemodialysis may be required if renal failure occurs. Awareness of toxicity and prevention remain the most important approaches.","Effects of hemodialysis and dimercaprol in acute dichromate poisoning Abs: A 22-month-old infant died after ingesting sodium dichromate his father had brought from work. Treatment included folic acid and dimercaprol administration, hemodialysis, and exchange transfusion. To evaluate this treatment, four dogs were hemodialyzed after receiving intravenous sodium dichromate: their dialyzer chromate clearance was similar to their renal chromate clearance and their dialyzer chromate clearance was not significantly different before or after dimercaprol administration. This and other cases in the literature indicate that although chromate poisoning is often fatal, supportive care, forced diuresis, and chelating agents may be helpful. Hemodialysis may be required if renal failure occurs. Awareness of toxicity and prevention remain the most important approaches."
1236158,Kusaimi and  Trentin 1982,Natural cell-mediated cytotoxic activity in the peripheral blood of patients with atopic dermatitis,"Ten patients with atopic dermatitis and ten healthy control subjects, matched for age, sex, and skin color, were studied for their peripheral blood natural cell-mediated cytotoxic activity against K-562 human leukemia cell line target cells, using the sodium chromate Cr 51 release assay. There was a great reduction in the natural cytotoxic activity of the patients with atopic dermatitis compared with that of their respective control subjects; the patients with atopic dermatitis had a mean value of 41.9 alpha +/- 28.3% of that of the control subjects.","Natural cell-mediated cytotoxic activity in the peripheral blood of patients with atopic dermatitis Abs: Ten patients with atopic dermatitis and ten healthy control subjects, matched for age, sex, and skin color, were studied for their peripheral blood natural cell-mediated cytotoxic activity against K-562 human leukemia cell line target cells, using the sodium chromate Cr 51 release assay. There was a great reduction in the natural cytotoxic activity of the patients with atopic dermatitis compared with that of their respective control subjects; the patients with atopic dermatitis had a mean value of 41.9 alpha +/- 28.3% of that of the control subjects."
1236157,Wall 1982,Chromate dermatitis and sodium dithionite,,Chromate dermatitis and sodium dithionite Abs: 
1236154,Breznock and  Strack 1982,Blood volume of nonsplenectomized and splenectomized cats before and after acute hemorrhage,"Blood volume (BV) was determined in awake, nonsplenectomized (NSPX) and splenectomized (SPX) cats before and after hemorrhage (6 ml/kg). Each NSPX cat had a determined BV at least 10 ml/kg greater than the same cat after splenectomy. The mean BV of SPX cats was 43.4 +/- 8.94. ml kg (4.3% of body weight). The calculated RBC masses of NSPX and SPX cats were 17.0 +/- 4.07 and 12.2 +/- 1.12 ml/kg, respectively. Each NSPX cat had apparent RBC masses of 5 ml/kg greater than that of the same cat after splenectomy was done. At 1 hour after a hemorrhage, the BV and RBC masses determined in SPX cats were 46.7 +/- 12.1 and 9.7 +/- 1.90 ml/kg, respectively. Extravascular-to-intravascular fluid flux (calculated from RBC masses and plasma protein dilution) was approximately 0.80% of body weight. The indirect method with 51Cr-labeled RBC for BV determination was accurate and precise in awake, SPX cats; in awake, NSPX cats, the 51Cr-labeled RBC dilution method was precise, but not accurate. The spleen in the cat resulted in marked overestimations of BV and RBC masses.","Blood volume of nonsplenectomized and splenectomized cats before and after acute hemorrhage Abs: Blood volume (BV) was determined in awake, nonsplenectomized (NSPX) and splenectomized (SPX) cats before and after hemorrhage (6 ml/kg). Each NSPX cat had a determined BV at least 10 ml/kg greater than the same cat after splenectomy. The mean BV of SPX cats was 43.4 +/- 8.94. ml kg (4.3% of body weight). The calculated RBC masses of NSPX and SPX cats were 17.0 +/- 4.07 and 12.2 +/- 1.12 ml/kg, respectively. Each NSPX cat had apparent RBC masses of 5 ml/kg greater than that of the same cat after splenectomy was done. At 1 hour after a hemorrhage, the BV and RBC masses determined in SPX cats were 46.7 +/- 12.1 and 9.7 +/- 1.90 ml/kg, respectively. Extravascular-to-intravascular fluid flux (calculated from RBC masses and plasma protein dilution) was approximately 0.80% of body weight. The indirect method with 51Cr-labeled RBC for BV determination was accurate and precise in awake, SPX cats; in awake, NSPX cats, the 51Cr-labeled RBC dilution method was precise, but not accurate. The spleen in the cat resulted in marked overestimations of BV and RBC masses."
1236153,Manciulea 1982,Quantitative determination of in vitro immunoglobulin secretion with protein A from Staphylococcus aureus,"A micromethod for the quantitative determination of Ig secreted in vitro by mice lymphocytes isolated from the spleen of normal animals is described. The indicator system consists in sheep erythrocytes radiolabelled with sodium chromate (51Cr) and coated with protein A of Staphylococcus aureus (51Cr-labelled ES). When splenocytes were incubated in fluid phase at 37 degrees C for 3 1/2 h with rabbit antisera to mouse Ig (IgM and IgG) and with guinea pig complement, the immune complexes formed between the secreted Ig and its specific IgG antibody are bound to protein A on the erythrocyte surface allowing the complement-mediated lysis of 51Cr-labelled ES. The degree of haemolysis produced in this experimental system, which reflects the amount of in vitro secreted Ig, was quantitatively measured by radioactive determination of 51Cr release. In combination with the ES plaque assay the method also gives information as immunoglobulin secretion per plaque forming cell.","Quantitative determination of in vitro immunoglobulin secretion with protein A from Staphylococcus aureus Abs: A micromethod for the quantitative determination of Ig secreted in vitro by mice lymphocytes isolated from the spleen of normal animals is described. The indicator system consists in sheep erythrocytes radiolabelled with sodium chromate (51Cr) and coated with protein A of Staphylococcus aureus (51Cr-labelled ES). When splenocytes were incubated in fluid phase at 37 degrees C for 3 1/2 h with rabbit antisera to mouse Ig (IgM and IgG) and with guinea pig complement, the immune complexes formed between the secreted Ig and its specific IgG antibody are bound to protein A on the erythrocyte surface allowing the complement-mediated lysis of 51Cr-labelled ES. The degree of haemolysis produced in this experimental system, which reflects the amount of in vitro secreted Ig, was quantitatively measured by radioactive determination of 51Cr release. In combination with the ES plaque assay the method also gives information as immunoglobulin secretion per plaque forming cell."
1236148,Koshi and  Iwasaki 1983,Solubility of low-solubility chromates and their clastogenic activity in cultured cells,"Low-solubility chromates, such as lead chromate, zinc chromate and calcium chromate, which were potent carcinogens, were examined for their solubility and clastogenic effects in a cultured Chinese hamster cell line (Don) as compared with those of potassium chromate, which was a high-solubility chromate and a weak carcinogen. Lead chromate was slightly soluble in water, Tyrode's solution, protein or amino acid solution, fetal calf serum and culture medium. Zinc chromate and calcium were less soluble in serum and Tyrode's solution than in water. There were good correlations between the frequencies of chromosomal aberrations in the cells treated with the chromates and Cr concentrations dissolved from these chromates in culture medium. When the frequency of chromosomal aberration in the cells exposed to the chromates was compared on equal amounts of dissolved Cr concentrations in culture medium, the frequency of chromosomal aberration was the most remarkable with lead chromate, followed by zinc chromate potassium chromate and calcium chromate. On column chromatographs by gel filtration on Sephadex G-200, the Cr dissolved from all chromates in culture medium was present with low molecular fraction. The carcinogenicity of low-solubility chromates might have been related to their low solubility in body fluid.","Solubility of low-solubility chromates and their clastogenic activity in cultured cells Abs: Low-solubility chromates, such as lead chromate, zinc chromate and calcium chromate, which were potent carcinogens, were examined for their solubility and clastogenic effects in a cultured Chinese hamster cell line (Don) as compared with those of potassium chromate, which was a high-solubility chromate and a weak carcinogen. Lead chromate was slightly soluble in water, Tyrode's solution, protein or amino acid solution, fetal calf serum and culture medium. Zinc chromate and calcium were less soluble in serum and Tyrode's solution than in water. There were good correlations between the frequencies of chromosomal aberrations in the cells treated with the chromates and Cr concentrations dissolved from these chromates in culture medium. When the frequency of chromosomal aberration in the cells exposed to the chromates was compared on equal amounts of dissolved Cr concentrations in culture medium, the frequency of chromosomal aberration was the most remarkable with lead chromate, followed by zinc chromate potassium chromate and calcium chromate. On column chromatographs by gel filtration on Sephadex G-200, the Cr dissolved from all chromates in culture medium was present with low molecular fraction. The carcinogenicity of low-solubility chromates might have been related to their low solubility in body fluid."
1236145,Pagano et al. 1983,The effects of hexavalent and trivalent chromium on fertilization and development in sea urchins,"The action of Cr6+ (as chromate) and Cr3+ (as sulfate and nitrate) on fertilization and development has been investigated in sea urchins. By rearing the embryos in the presence of chromate (5 X 10(-5) to 5 X 10(-4) M), the differentiation of the gut and skeleton was severely affected. The treatment of sperm before fertilization with CrO2- 4 (10 to 30 min, 10(-4) to 10(-2) M) resulted in a number of abnormal larvae, depending on the length of exposure and the CrO2- 4 concentration. Morphological and quantitative changes of mitotic activity during cleavage were observed as a result of CrO2- 4 exposure of zygotes, as well as of sperm and egg pretreatment. The exposure of embryos to Cr3+ after fertilization permitted larval differentiation, but affected the motility and hatchability of the embryos. The pretreatment of gametes with Cr3+ never induced larval malformations. Cr3+ exerted a strong depressive action on fertilization by decreasing the fertilizing capacity of sperm and leaving the fertilizability of the eggs almost unaffected.","The effects of hexavalent and trivalent chromium on fertilization and development in sea urchins Abs: The action of Cr6+ (as chromate) and Cr3+ (as sulfate and nitrate) on fertilization and development has been investigated in sea urchins. By rearing the embryos in the presence of chromate (5 X 10(-5) to 5 X 10(-4) M), the differentiation of the gut and skeleton was severely affected. The treatment of sperm before fertilization with CrO2- 4 (10 to 30 min, 10(-4) to 10(-2) M) resulted in a number of abnormal larvae, depending on the length of exposure and the CrO2- 4 concentration. Morphological and quantitative changes of mitotic activity during cleavage were observed as a result of CrO2- 4 exposure of zygotes, as well as of sperm and egg pretreatment. The exposure of embryos to Cr3+ after fertilization permitted larval differentiation, but affected the motility and hatchability of the embryos. The pretreatment of gametes with Cr3+ never induced larval malformations. Cr3+ exerted a strong depressive action on fertilization by decreasing the fertilizing capacity of sperm and leaving the fertilizability of the eggs almost unaffected."
1236142,Tsapakos et al. 1983,The carcinogen chromate causes DNA damage and inhibits drug-mediated induction of porphyrin accumulation and glucuronidation in chick embryo hepatocytes,"DNA damage by chromate in chick embryo hepatocytes has been correlated with the effect of chromate on inducible cell functions. Treatment of chick embryo hepatocytes with chromium(VI) in the form of sodium chromate resulted in the rapid uptake of chromate and the induction of DNA lesions in a time- and concentration-dependent manner. DNA interstrand cross-links, strand breaks and DNA-protein crosslinks, as measured by the alkaline elution technique, were observed after treatment of the hepatocytes with chromate concentrations (2.5- 0 microM) which did not affect cell viability. The effect of chromate on inducible cell functions was measured by assaying propylisopropylacetamide-induced accumulation of porphyrin and glucuronidation of phenol red by intact cells. Chromate inhibited propylisopropylacetamide-induction of porphyrin accumulation and phenol red glucuronidation in a time- and concentration-dependent manner which paralleled DNA damage. DNA damage was removed and inducibility of porphyrin accumulation by propylisopropylacetamide plus deferoxamine methanesulfonate was restored 21 h following a 2 h pretreatment with chromate. Chromium(III) in the form of chromic nitrate at concentrations up to 25 times those used with chromate had no effect on DNA damage or the induction of porphyrin accumulation and phenol red glucuronidation by propylisopropylacetamide in the cultured chick hepatocytes.","The carcinogen chromate causes DNA damage and inhibits drug-mediated induction of porphyrin accumulation and glucuronidation in chick embryo hepatocytes Abs: DNA damage by chromate in chick embryo hepatocytes has been correlated with the effect of chromate on inducible cell functions. Treatment of chick embryo hepatocytes with chromium(VI) in the form of sodium chromate resulted in the rapid uptake of chromate and the induction of DNA lesions in a time- and concentration-dependent manner. DNA interstrand cross-links, strand breaks and DNA-protein crosslinks, as measured by the alkaline elution technique, were observed after treatment of the hepatocytes with chromate concentrations (2.5- 0 microM) which did not affect cell viability. The effect of chromate on inducible cell functions was measured by assaying propylisopropylacetamide-induced accumulation of porphyrin and glucuronidation of phenol red by intact cells. Chromate inhibited propylisopropylacetamide-induction of porphyrin accumulation and phenol red glucuronidation in a time- and concentration-dependent manner which paralleled DNA damage. DNA damage was removed and inducibility of porphyrin accumulation by propylisopropylacetamide plus deferoxamine methanesulfonate was restored 21 h following a 2 h pretreatment with chromate. Chromium(III) in the form of chromic nitrate at concentrations up to 25 times those used with chromate had no effect on DNA damage or the induction of porphyrin accumulation and phenol red glucuronidation by propylisopropylacetamide in the cultured chick hepatocytes."
1236138,Tsapakos et al. 1983,"Chromium(VI)-induced DNA lesions and chromium distribution in rat kidney, liver, and lung","DNA lesions were detected in rat organ nuclei following an i.p. injection of sodium dichromate. Kidney, liver, and lung nuclei were examined for DNA interstrand cross-links, strand breaks, and DNA-protein cross-links using the alkaline elution technique. The time course for formation of cross-links in kidney nuclei revealed the presence of DNA interstrand and DNA-protein cross-links 1 hr after injection of sodium dichromate. By 40 hr in kidney, DNA interstrand cross-links had been repaired, but DNA-protein cross-links persisted. In liver nuclei, the time course for formation of cross-links after injection of dichromate showed a maximum in DNA-protein cross-linking at 4 hr and a maximum in DNA interstrand cross-linking at 2 hr. By 36 hr, in the liver, both types of lesions had been repaired. In lung nuclei, both DNA interstrand and DNA-protein cross-links were observed 1 hr after dichromate injection; however, by 36 hr, only DNA-protein cross-links persisted. No DNA lesions were detectable in kidney 1 hr after an i.p. injection of chromium(III) chloride. Chromium distribution in rat kidney, liver, and lung was measured and is discussed with respect to the observed DNA lesions. The lung and kidney may be more sensitive than liver to chromium-induced DNA damage, an observation which correlates with the reported toxicity and carcinogenicity data for chromium(VI) in both animals and humans.","Chromium(VI)-induced DNA lesions and chromium distribution in rat kidney, liver, and lung Abs: DNA lesions were detected in rat organ nuclei following an i.p. injection of sodium dichromate. Kidney, liver, and lung nuclei were examined for DNA interstrand cross-links, strand breaks, and DNA-protein cross-links using the alkaline elution technique. The time course for formation of cross-links in kidney nuclei revealed the presence of DNA interstrand and DNA-protein cross-links 1 hr after injection of sodium dichromate. By 40 hr in kidney, DNA interstrand cross-links had been repaired, but DNA-protein cross-links persisted. In liver nuclei, the time course for formation of cross-links after injection of dichromate showed a maximum in DNA-protein cross-linking at 4 hr and a maximum in DNA interstrand cross-linking at 2 hr. By 36 hr, in the liver, both types of lesions had been repaired. In lung nuclei, both DNA interstrand and DNA-protein cross-links were observed 1 hr after dichromate injection; however, by 36 hr, only DNA-protein cross-links persisted. No DNA lesions were detectable in kidney 1 hr after an i.p. injection of chromium(III) chloride. Chromium distribution in rat kidney, liver, and lung was measured and is discussed with respect to the observed DNA lesions. The lung and kidney may be more sensitive than liver to chromium-induced DNA damage, an observation which correlates with the reported toxicity and carcinogenicity data for chromium(VI) in both animals and humans."
1236137,Robbins et al. 1984,Comparative effects of aspirin and enteric-coated aspirin on loss of chromium 51-labeled erythrocytes from the gastrointestinal tract,"Sodium chromate Cr 51 was used to label red blood cells of 19 healthy male volunteers, whose stools were collected for four days before and four days during oral administration of either uncoated (N = 9) or enteric-coated (N = 10) aspirin. Each subject received 2.925 gm/day of aspirin, in three equal doses separated by eight-hour intervals, for a total of seven days. During drug use, stools were collected on days 4 through 7. Fecal blood content, estimated by measuring radioactivity in the stools, was significantly higher (P less than 0.001) during use of either type of aspirin than at baseline, but losses measured during use of the coated aspirin (mean, 1.54 ml/day) were significantly lower (P less than 0.001) than those measured during use of the uncoated aspirin (mean, 4.33 ml/day). The two types of aspirin produced equivalent serum concentrations of salicylates. We conclude that enteric-coated aspirin reduces gastrointestinal blood loss.","Comparative effects of aspirin and enteric-coated aspirin on loss of chromium 51-labeled erythrocytes from the gastrointestinal tract Abs: Sodium chromate Cr 51 was used to label red blood cells of 19 healthy male volunteers, whose stools were collected for four days before and four days during oral administration of either uncoated (N = 9) or enteric-coated (N = 10) aspirin. Each subject received 2.925 gm/day of aspirin, in three equal doses separated by eight-hour intervals, for a total of seven days. During drug use, stools were collected on days 4 through 7. Fecal blood content, estimated by measuring radioactivity in the stools, was significantly higher (P less than 0.001) during use of either type of aspirin than at baseline, but losses measured during use of the coated aspirin (mean, 1.54 ml/day) were significantly lower (P less than 0.001) than those measured during use of the uncoated aspirin (mean, 4.33 ml/day). The two types of aspirin produced equivalent serum concentrations of salicylates. We conclude that enteric-coated aspirin reduces gastrointestinal blood loss."
1236133,Bowman and  Shoeb 1984,Effect of oxygen radical scavengers on K-cell cytolysis,"We have shown that the hydroxyl radical scavengers sodium benzoate, phenol, dimethyl sulfoxide, sodium formate, and mannitol protect chicken erythrocyte (Ec) target cells from lysis by K-cells in plaque assays. The protection afforded by benzoate, phenol, mannitol, and dimethyl sulfoxide was abrogated if the target cells were pretreated with sodium chromate. Neither superoxide dismutase nor catalase protected Ec target cells, indicating that superoxide and H2O2 are not involved in lysis. The lysis obtained on chromium-treated Ec target cells in the presence of benzoate, phenol, and mannitol is likely due to singlet oxygen, because 1,4-diazabicyclo[2.2.2]octane and bilirubin, singlet oxygen scavengers, protected chromium-treated Ec target cells in the presence of phenol. Ec target cells not treated with chromium were not protected by either of the singlet oxygen scavengers.","Effect of oxygen radical scavengers on K-cell cytolysis Abs: We have shown that the hydroxyl radical scavengers sodium benzoate, phenol, dimethyl sulfoxide, sodium formate, and mannitol protect chicken erythrocyte (Ec) target cells from lysis by K-cells in plaque assays. The protection afforded by benzoate, phenol, mannitol, and dimethyl sulfoxide was abrogated if the target cells were pretreated with sodium chromate. Neither superoxide dismutase nor catalase protected Ec target cells, indicating that superoxide and H2O2 are not involved in lysis. The lysis obtained on chromium-treated Ec target cells in the presence of benzoate, phenol, and mannitol is likely due to singlet oxygen, because 1,4-diazabicyclo[2.2.2]octane and bilirubin, singlet oxygen scavengers, protected chromium-treated Ec target cells in the presence of phenol. Ec target cells not treated with chromium were not protected by either of the singlet oxygen scavengers."
1236129,Williams et al. 1984,Clearance from the anterior chamber of RBCs from human diabetics,"Erythrocytes from diabetic patients manifest decreased deformability and increased adherence. These abnormal membrane properties may diminish the ability of erythrocytes (RBCs) from diabetics to undergo deformation in passage through the trabecular meshwork. Using sodium chromate Cr 51-labeled RBCs from type I diabetic patients with proliferative retinopathy and normal control subjects, we studied RBC clearance from the rabbit anterior chamber. The mean time for 50% clearance (T50) of RBCs from diabetics (76 hours) was significantly longer than that for RBCs from normal subjects (19.5 hours). In this model, RBCs from diabetics have a slower clearance from the anterior chamber than do RBCs from normal subjects.","Clearance from the anterior chamber of RBCs from human diabetics Abs: Erythrocytes from diabetic patients manifest decreased deformability and increased adherence. These abnormal membrane properties may diminish the ability of erythrocytes (RBCs) from diabetics to undergo deformation in passage through the trabecular meshwork. Using sodium chromate Cr 51-labeled RBCs from type I diabetic patients with proliferative retinopathy and normal control subjects, we studied RBC clearance from the rabbit anterior chamber. The mean time for 50% clearance (T50) of RBCs from diabetics (76 hours) was significantly longer than that for RBCs from normal subjects (19.5 hours). In this model, RBCs from diabetics have a slower clearance from the anterior chamber than do RBCs from normal subjects."
1236128,Tsan 1984,Kinetics and distribution of platelets in man,"51Cr sodium-chromate, though having been widely used in the last two decades for labeling platelets, suffers from several serious drawbacks, ie, low labeling efficiency, long physical half-life, and low gamma photon yields. 111In-oxine and 111In-tropolone overcome these shortcomings and have the potential of precise determination of platelet kinetics as well as visualization and in vivo quantification of the temporal and spatial distribution of platelets in man. Computer analysis of platelet kinetics reveals that the multiple-hit model fits the survival curve better than the linear or the exponential model. The multiple-hit model provides not only the mean platelet survival time but also information on the initial recovery and the shape of the survival curve. The application of these techniques in normal and disease states should greatly enhance our understanding of the physiology and pathophysiology of platelets.","Kinetics and distribution of platelets in man Abs: 51Cr sodium-chromate, though having been widely used in the last two decades for labeling platelets, suffers from several serious drawbacks, ie, low labeling efficiency, long physical half-life, and low gamma photon yields. 111In-oxine and 111In-tropolone overcome these shortcomings and have the potential of precise determination of platelet kinetics as well as visualization and in vivo quantification of the temporal and spatial distribution of platelets in man. Computer analysis of platelet kinetics reveals that the multiple-hit model fits the survival curve better than the linear or the exponential model. The multiple-hit model provides not only the mean platelet survival time but also information on the initial recovery and the shape of the survival curve. The application of these techniques in normal and disease states should greatly enhance our understanding of the physiology and pathophysiology of platelets."
1236127,English and  Clanton 1984,Evaluation of neutrophil labeling techniques using the chemotaxis radioassay,"Neutrophils isolated from human blood were labeled by various methods and exposed to a chemotactic gradient. The chemotactically functional cells that migrated into the gradient were isolated. The portion of radioactivity of the original cell suspension carried with the chemotactically responsive cells was related to the relative number of migrating cells as determined microscopically. Of the radionuclides used, P-32 diisopropylfluorophosphate (DFP), In-111 oxine, and Tc-99m sulfur colloid provided cell preparations with the highest relative portion of radioactivity confined to functionally intact (chemotactic) neutrophils. Results with Na2(51)CrO4 and with SnCl2-reduced 99mTcO4- were less than optimal. Neutrophils exposed to Ga-67 citrate apparently took up the label and retained chemotactic responsiveness. However, little or no radioactivity was detected in the neutrophils that migrated from the suspensions of Ga-67-labeled cells. The results indicate that the chemotaxis radioassay can yield unique information pertaining to the extent to which a radiotracer is specifically associated with viable neutrophils in a suspension of labeled cells.","Evaluation of neutrophil labeling techniques using the chemotaxis radioassay Abs: Neutrophils isolated from human blood were labeled by various methods and exposed to a chemotactic gradient. The chemotactically functional cells that migrated into the gradient were isolated. The portion of radioactivity of the original cell suspension carried with the chemotactically responsive cells was related to the relative number of migrating cells as determined microscopically. Of the radionuclides used, P-32 diisopropylfluorophosphate (DFP), In-111 oxine, and Tc-99m sulfur colloid provided cell preparations with the highest relative portion of radioactivity confined to functionally intact (chemotactic) neutrophils. Results with Na2(51)CrO4 and with SnCl2-reduced 99mTcO4- were less than optimal. Neutrophils exposed to Ga-67 citrate apparently took up the label and retained chemotactic responsiveness. However, little or no radioactivity was detected in the neutrophils that migrated from the suspensions of Ga-67-labeled cells. The results indicate that the chemotaxis radioassay can yield unique information pertaining to the extent to which a radiotracer is specifically associated with viable neutrophils in a suspension of labeled cells."
1236125,Kurzweil et al. 1984,Use of sodium chromate Cr51 in diagnosing childhood idiopathic pulmonary hemosiderosis,"The diagnosis of idiopathic pulmonary hemosiderosis (IPH) may be elusive. A 6-year-old boy had microcytic hypochromic anemia and a hemolytic component. Hemosiderin-laden macrophages were not found in the gastric aspirate. He had no pulmonary signs or symptoms. Extensive hematologic and roentgenologic investigations failed to reveal the cause of the anemia. Quantitative serial scintigraphic scanning showed significant (35%) pulmonary sequestration of autologous erythrocytes labeled with sodium chromate Cr51. The half-life of the RBCs was moderately decreased (half-life, 15 days; normal, 25 to 35 days). An open-lung biopsy specimen confirmed the diagnosis of IPH. A diagnosis of IPH should be considered when children have iron deficiency anemia and pulmonary signs or symptoms. Organ sequestration studies may be helpful in equivocal cases.","Use of sodium chromate Cr51 in diagnosing childhood idiopathic pulmonary hemosiderosis Abs: The diagnosis of idiopathic pulmonary hemosiderosis (IPH) may be elusive. A 6-year-old boy had microcytic hypochromic anemia and a hemolytic component. Hemosiderin-laden macrophages were not found in the gastric aspirate. He had no pulmonary signs or symptoms. Extensive hematologic and roentgenologic investigations failed to reveal the cause of the anemia. Quantitative serial scintigraphic scanning showed significant (35%) pulmonary sequestration of autologous erythrocytes labeled with sodium chromate Cr51. The half-life of the RBCs was moderately decreased (half-life, 15 days; normal, 25 to 35 days). An open-lung biopsy specimen confirmed the diagnosis of IPH. A diagnosis of IPH should be considered when children have iron deficiency anemia and pulmonary signs or symptoms. Organ sequestration studies may be helpful in equivocal cases."
1236124,Cantoni and  Costa 1984,Analysis of the induction of alkali sensitive sites in the DNA by chromate and other agents that induce single strand breaks,"CaCrO4 was shown to induce alkali labile sites in the DNA of Chinese hamster ovary cells by analysis of the lack of linearity in the alkaline elution curves, and by a study of the dependence upon pH in the elution of DNA from filters. The effect of CaCrO4 on these parameters was compared with N-methyl-N-nitrosourea, an agent known to produce alkali labile sites. Based upon the aforementioned parameters HgCl2, formaldehyde and X-rays caused the formation of frank single strand breaks with little or no induction of alkaline labile sites. These findings demonstrate differences in the production of alkali sensitive sites by agents that cause DNA single strand breaks.","Analysis of the induction of alkali sensitive sites in the DNA by chromate and other agents that induce single strand breaks Abs: CaCrO4 was shown to induce alkali labile sites in the DNA of Chinese hamster ovary cells by analysis of the lack of linearity in the alkaline elution curves, and by a study of the dependence upon pH in the elution of DNA from filters. The effect of CaCrO4 on these parameters was compared with N-methyl-N-nitrosourea, an agent known to produce alkali labile sites. Based upon the aforementioned parameters HgCl2, formaldehyde and X-rays caused the formation of frank single strand breaks with little or no induction of alkaline labile sites. These findings demonstrate differences in the production of alkali sensitive sites by agents that cause DNA single strand breaks."
1236123,Cupo and  Wetterhahn 1984,Repair of chromate-induced DNA damage in chick embryo hepatocytes,"The repair of DNA damage caused by chromate was examined in chick embryo hepatocytes. Treatment of chick embryo hepatocytes with 5 microM sodium chromate for 2 h caused the formation of DNA strand breaks, DNA interstrand cross-links, and DNA-protein cross-links. The maximal level of strand breaks and DNA interstrand cross-links was observed immediately after the 2 h chromate treatment. After removal of the chromate, strand breaks and DNA interstrand cross-links were completely repaired by 3 h and 12 h, respectively. In contrast, DNA-protein cross-links continued to form reaching a maximal level 3 h after chromate removal. Although the level of DNA-protein cross-links decreased at later times, a significant level persisted 40 h after chromate removal. The effect of these persistent DNA-protein cross-links on gene expression was examined by measuring induction of porphyrin accumulation by propylisopropylacetamide and deferoxamine methanesulphonate, a process known to depend on mRNA synthesis. Induction of porphyrin accumulation was decreased immediately following the 2 h chromate treatment. Only partial recovery of induction was observed even 40 h after chromate removal. The effect of chromate treatment on cellular glutathione levels was monitored. No change in cellular glutathione was observed after a 2 h treatment with 5 microM sodium chromate; however, a three-fold increase was observed 12 h after removal of chromate.","Repair of chromate-induced DNA damage in chick embryo hepatocytes Abs: The repair of DNA damage caused by chromate was examined in chick embryo hepatocytes. Treatment of chick embryo hepatocytes with 5 microM sodium chromate for 2 h caused the formation of DNA strand breaks, DNA interstrand cross-links, and DNA-protein cross-links. The maximal level of strand breaks and DNA interstrand cross-links was observed immediately after the 2 h chromate treatment. After removal of the chromate, strand breaks and DNA interstrand cross-links were completely repaired by 3 h and 12 h, respectively. In contrast, DNA-protein cross-links continued to form reaching a maximal level 3 h after chromate removal. Although the level of DNA-protein cross-links decreased at later times, a significant level persisted 40 h after chromate removal. The effect of these persistent DNA-protein cross-links on gene expression was examined by measuring induction of porphyrin accumulation by propylisopropylacetamide and deferoxamine methanesulphonate, a process known to depend on mRNA synthesis. Induction of porphyrin accumulation was decreased immediately following the 2 h chromate treatment. Only partial recovery of induction was observed even 40 h after chromate removal. The effect of chromate treatment on cellular glutathione levels was monitored. No change in cellular glutathione was observed after a 2 h treatment with 5 microM sodium chromate; however, a three-fold increase was observed 12 h after removal of chromate."
1236122,Lippert et al. 1984,Detection of enteric-urinary fistulas with a noninvasive quantitative method,"The 51chromium test is an inexpensive, noninvasive test to evaluate patients for enteric-urinary fistulas. Of 11 patients studied the 51chromium test demonstrated correctly a fistula in 5 of 6 patients with fistulas and showed no lesion in all 5 without fistulas. Excretory urography, barium enemas, visible contrast medium, cystograms and upper gastrointestinal series failed to demonstrate the fistulas with similar accuracy. Cystoscopy suggested a possible lesion in 4 patients but was definite for a fistula in only 2 of those patients.","Detection of enteric-urinary fistulas with a noninvasive quantitative method Abs: The 51chromium test is an inexpensive, noninvasive test to evaluate patients for enteric-urinary fistulas. Of 11 patients studied the 51chromium test demonstrated correctly a fistula in 5 of 6 patients with fistulas and showed no lesion in all 5 without fistulas. Excretory urography, barium enemas, visible contrast medium, cystograms and upper gastrointestinal series failed to demonstrate the fistulas with similar accuracy. Cystoscopy suggested a possible lesion in 4 patients but was definite for a fistula in only 2 of those patients."
1236120,Roccatello et al. 1985,In vitro study of Fc-receptor function in autoimmune diseases,"A simple test for studying in vitro Fc-receptor function of mononuclear phagocytes is described. Immune phagocytosis is analyzed as a dynamic phenomenon by using nearly pure suspensions of monocytes incubated for diverse times with autologous erythrocytes sensitized with highly purified IgG. In a series of normal volunteers and patients with vasculitis a strict correlation has been found between this in vitro assay and the measure of splenic clearance of IgG-coated red blood cells (RBC), the classical approach for studying in vivo macrophage Fc-receptor function by using sodium chromate 51Cr as tag. The use of this in vitro assay appears to be valuable mainly in cases requiring repeated measurements of Fc-receptor function for monitoring the course of disease or the effects of therapy.","In vitro study of Fc-receptor function in autoimmune diseases Abs: A simple test for studying in vitro Fc-receptor function of mononuclear phagocytes is described. Immune phagocytosis is analyzed as a dynamic phenomenon by using nearly pure suspensions of monocytes incubated for diverse times with autologous erythrocytes sensitized with highly purified IgG. In a series of normal volunteers and patients with vasculitis a strict correlation has been found between this in vitro assay and the measure of splenic clearance of IgG-coated red blood cells (RBC), the classical approach for studying in vivo macrophage Fc-receptor function by using sodium chromate 51Cr as tag. The use of this in vitro assay appears to be valuable mainly in cases requiring repeated measurements of Fc-receptor function for monitoring the course of disease or the effects of therapy."
1236119,Wiegand et al. 1985,The formation of glutathione-chromium complexes and their possible role in chromium disposition,"The reduction of Cr(VI) to Cr(III) by glutathione (GSH) in vitro resulted in the formation of two different GSH-chromium complexes with an approximate molecular-weight of 10,000 and 5000, respectively. Both complexes exhibited strong fluorescence. The molar ratio between oxidized glutathione (GSSG) and chromium was calculated by determining the chromium content of the two isolated complex species by flameless Atomic Absorption Spectrometry (AAS).","The formation of glutathione-chromium complexes and their possible role in chromium disposition Abs: The reduction of Cr(VI) to Cr(III) by glutathione (GSH) in vitro resulted in the formation of two different GSH-chromium complexes with an approximate molecular-weight of 10,000 and 5000, respectively. Both complexes exhibited strong fluorescence. The molar ratio between oxidized glutathione (GSSG) and chromium was calculated by determining the chromium content of the two isolated complex species by flameless Atomic Absorption Spectrometry (AAS)."
1236118,Ebaugh and  Ross 1985,The radioactive sodium chromate method for erythrocyte survival,,The radioactive sodium chromate method for erythrocyte survival Abs: 
1236116,Akerström and  Landin 1985,Rat alpha 1-microglobulin. Purification from urine and synthesis by hepatocyte monolayers,"Rat alpha 1-microglobulin was isolated from the urine of rats treated with sodium chromate, and was purified by the use of gel chromatography, affinity chromatography on concanavalin-A-Sepharose and ion-exchange chromatography. The protein was heterogeneous in charge, had a tendency to form dimers, and was associated with a brown-coloured chromophore. The size of the protein (25 kDa) was similar to guinea pig alpha 1-microglobulin but smaller than the human protein, when measured with sodium dodecyl sulfate/polyacrylamide gel electrophoresis. Immunological cross-reaction with human and guinea pig alpha 1-microglobulin was demonstrated. The concentration of alpha 1-microglobulin in rat serum was 16.4 mg/l (SD = 8.5 mg/l, n = 13) and rat serum alpha 1-microglobulin was eluted from a gel chromatography column at two different positions corresponding to monomeric alpha 1-microglobulin and IgA. The latter alpha 1-microglobulin activity could be absorbed by anti-IgA serum. Rat alpha 1-microglobulin and albumin were continuously released into the medium of rat hepatocyte monolayers, and alpha 1-microglobulin was isolated from the medium by the use of immunoprecipitation with anti-(alpha 1-microglobulin). Tritiated leucine, added to the medium, was incorporated into the protein, suggesting a de novo synthesis of alpha 1-microglobulin by the hepatocytes. The size of hepatic alpha 1-microglobulin was similar to that of purified urinary rat alpha 1-microglobulin, when determined with sodium dodecyl sulfate/polyacrylamide gel electrophoresis.","Rat alpha 1-microglobulin. Purification from urine and synthesis by hepatocyte monolayers Abs: Rat alpha 1-microglobulin was isolated from the urine of rats treated with sodium chromate, and was purified by the use of gel chromatography, affinity chromatography on concanavalin-A-Sepharose and ion-exchange chromatography. The protein was heterogeneous in charge, had a tendency to form dimers, and was associated with a brown-coloured chromophore. The size of the protein (25 kDa) was similar to guinea pig alpha 1-microglobulin but smaller than the human protein, when measured with sodium dodecyl sulfate/polyacrylamide gel electrophoresis. Immunological cross-reaction with human and guinea pig alpha 1-microglobulin was demonstrated. The concentration of alpha 1-microglobulin in rat serum was 16.4 mg/l (SD = 8.5 mg/l, n = 13) and rat serum alpha 1-microglobulin was eluted from a gel chromatography column at two different positions corresponding to monomeric alpha 1-microglobulin and IgA. The latter alpha 1-microglobulin activity could be absorbed by anti-IgA serum. Rat alpha 1-microglobulin and albumin were continuously released into the medium of rat hepatocyte monolayers, and alpha 1-microglobulin was isolated from the medium by the use of immunoprecipitation with anti-(alpha 1-microglobulin). Tritiated leucine, added to the medium, was incorporated into the protein, suggesting a de novo synthesis of alpha 1-microglobulin by the hepatocytes. The size of hepatic alpha 1-microglobulin was similar to that of purified urinary rat alpha 1-microglobulin, when determined with sodium dodecyl sulfate/polyacrylamide gel electrophoresis."
1236115,Walpole et al. 1985,Acute chromium poisoning in a 2 year old child,"Sodium dichromate ingestion in children is uncommon and potentially lethal. The most appropriate management is uncertain because of the lack of sound data contained in the few reports of successfully treated patients. Immediate treatment should include urgent induction of emesis, administration of ascorbic acid as an antidote, followed by supportive treatment.","Acute chromium poisoning in a 2 year old child Abs: Sodium dichromate ingestion in children is uncommon and potentially lethal. The most appropriate management is uncertain because of the lack of sound data contained in the few reports of successfully treated patients. Immediate treatment should include urgent induction of emesis, administration of ascorbic acid as an antidote, followed by supportive treatment."
1236111,Romaguera et al. 1985,Formulation of a barrier cream against chromate,"A topical cosmetic cream has been developed for use on patients occupationally sensitized to chromate. With the components of this preparation, an in vitro study was carried out, which demonstrated the efficiency of each component. An in vivo experiment on 25 volunteer patients proved a failure. The formula was modified to produce a new cream. The in vitro and in vivo experiences showed satisfactory results in 60 volunteer patients, 60% of whom benefitted from using it.","Formulation of a barrier cream against chromate Abs: A topical cosmetic cream has been developed for use on patients occupationally sensitized to chromate. With the components of this preparation, an in vitro study was carried out, which demonstrated the efficiency of each component. An in vivo experiment on 25 volunteer patients proved a failure. The formula was modified to produce a new cream. The in vitro and in vivo experiences showed satisfactory results in 60 volunteer patients, 60% of whom benefitted from using it."
1236106,Cupo and  Wetterhahn 1985,Modification of chromium(VI)-induced DNA damage by glutathione and cytochromes P-450 in chicken embryo hepatocytes,"The role of glutathione and cytochrome P-450 in the production of DNA damage by chromium(VI) was examined in chicken embryo hepatocytes by the alkaline elution technique. Cellular levels of glutathione and cytochrome P-450 were altered by treating the hepatocytes with N-acetyl-L-cysteine, buthionine sulfoximine, isopentanol, or beta-naphthoflavone. A dramatic increase in chromium(VI)-induced DNA strand breaks was observed after increasing glutathione levels in the cells. Chromium(VI)-induced DNA strand breaks were even more numerous when the level of cytochrome P-450 was also increased. Upon depletion of glutathione levels and induction of cytochrome P-450 or cytochrome P-448, little or no DNA strand breaks or DNA interstrand cross-links were observed after chromium(VI) treatment. Chromium(VI)-induced DNA-protein cross-links generally decreased after either increases or decreases in cellular levels of glutathione or cytochrome P-450 or P-448. These results suggest that glutathione enhances chromium(VI)-induced DNA damage through metabolic activation of chromium(VI). The possible production of reactive chromium species upon metabolism by glutathione and cytochrome P-450 or P-448 and their involvement in DNA damage is discussed.","Modification of chromium(VI)-induced DNA damage by glutathione and cytochromes P-450 in chicken embryo hepatocytes Abs: The role of glutathione and cytochrome P-450 in the production of DNA damage by chromium(VI) was examined in chicken embryo hepatocytes by the alkaline elution technique. Cellular levels of glutathione and cytochrome P-450 were altered by treating the hepatocytes with N-acetyl-L-cysteine, buthionine sulfoximine, isopentanol, or beta-naphthoflavone. A dramatic increase in chromium(VI)-induced DNA strand breaks was observed after increasing glutathione levels in the cells. Chromium(VI)-induced DNA strand breaks were even more numerous when the level of cytochrome P-450 was also increased. Upon depletion of glutathione levels and induction of cytochrome P-450 or cytochrome P-448, little or no DNA strand breaks or DNA interstrand cross-links were observed after chromium(VI) treatment. Chromium(VI)-induced DNA-protein cross-links generally decreased after either increases or decreases in cellular levels of glutathione or cytochrome P-450 or P-448. These results suggest that glutathione enhances chromium(VI)-induced DNA damage through metabolic activation of chromium(VI). The possible production of reactive chromium species upon metabolism by glutathione and cytochrome P-450 or P-448 and their involvement in DNA damage is discussed."
1236101,Eisenberg et al. 1986,Enhancement of red blood cell proton relaxation with chromium labeling,"Nuclear medicine has utilized chromium (Cr) for decades to label red blood cells (RBCs). The purpose of this project was to determine whether sufficient paramagnetic Cr could be bound to red cells to influence proton relaxation significantly. We demonstrated that the T1 and T2 of RBCs can be substantially shortened by labeling them with paramagnetic Cr. Proton relaxation enhancement occurs when red cells are incubated with sodium chromate (VI) over a concentration range of 0.10 mM to 31.6 mM. Labeling with Cr at a concentration of 31.6 mM shortened the T1 of packed cells from 714 msec to 33 msec, and the T2 from 117 msec to 24 msec, as compared with nonlabeled red cells. In vitro hemolysis was significantly increased after labeling at 31.6 mM, but not at lower concentrations. Cr-induced proton relaxation enhancement varied with RBCs from different species, temperature, pH, and length of incubation. T1 values of kidneys containing labeled red cells (303 msec), or labeled cells diluted 10-fold with nonlabeled cells (479 msec), were decreased compared with kidneys containing only nonlabeled cells (600 msec). Finally, preliminary data indicate that the signal intensity of perfused renal tissue is significantly influenced in vivo by infusion of Cr-labeled RBCs. This study demonstrated that Cr labeling of RBCs sufficiently enhances red cell proton relaxation to provide excised organs containing red cells, of which 10% have been Cr-labeled, with shorter T1 and T2 values than organs containing nonlabeled cells. In addition, the ability of labeled cells to alter signal intensity in vivo suggests that Cr may have the potential to become an MRI contrast agent.","Enhancement of red blood cell proton relaxation with chromium labeling Abs: Nuclear medicine has utilized chromium (Cr) for decades to label red blood cells (RBCs). The purpose of this project was to determine whether sufficient paramagnetic Cr could be bound to red cells to influence proton relaxation significantly. We demonstrated that the T1 and T2 of RBCs can be substantially shortened by labeling them with paramagnetic Cr. Proton relaxation enhancement occurs when red cells are incubated with sodium chromate (VI) over a concentration range of 0.10 mM to 31.6 mM. Labeling with Cr at a concentration of 31.6 mM shortened the T1 of packed cells from 714 msec to 33 msec, and the T2 from 117 msec to 24 msec, as compared with nonlabeled red cells. In vitro hemolysis was significantly increased after labeling at 31.6 mM, but not at lower concentrations. Cr-induced proton relaxation enhancement varied with RBCs from different species, temperature, pH, and length of incubation. T1 values of kidneys containing labeled red cells (303 msec), or labeled cells diluted 10-fold with nonlabeled cells (479 msec), were decreased compared with kidneys containing only nonlabeled cells (600 msec). Finally, preliminary data indicate that the signal intensity of perfused renal tissue is significantly influenced in vivo by infusion of Cr-labeled RBCs. This study demonstrated that Cr labeling of RBCs sufficiently enhances red cell proton relaxation to provide excised organs containing red cells, of which 10% have been Cr-labeled, with shorter T1 and T2 values than organs containing nonlabeled cells. In addition, the ability of labeled cells to alter signal intensity in vivo suggests that Cr may have the potential to become an MRI contrast agent."
1236099,Dewanjee et al. 1986,Comparison of three platelet markers for measurement of platelet survival time in healthy volunteers,"We studied mean platelet survival times in healthy volunteers with use of [51Cr]disodium chromate, 111In-oxine (in a solution of acid-citrate-dextrose [ACD] and saline), and 111In-tropolone (in ACD-plasma) as markers. Differences found between the 51Cr and 111In labels probably can be attributed to a variation in localization of the label on the cell and of renal handling of the free label after release. The mean platelet survival time with 51Cr was slightly longer than the survival time with both indium labels and showed a sex difference not seen with 111In-oxine. Protein-bound plasma 51Cr was lower than plasma 111In and remained constant throughout the study. Plasma 111In increased with time. For survival time calculations, no correction for free 51Cr is necessary, but correction should routinely be performed when 111In markers are used. Both 111In markers gave similar results with respect to platelet survival time. The somewhat more elaborate plasma labeling procedure with tropolone shows no measurable advantage over the original 111In-oxine method. 111In-tropolone labeling takes less time and maintains platelets in the physiologic environment of plasma during incubation. Biodistribution studies show no difference between the two 111In markers.","Comparison of three platelet markers for measurement of platelet survival time in healthy volunteers Abs: We studied mean platelet survival times in healthy volunteers with use of [51Cr]disodium chromate, 111In-oxine (in a solution of acid-citrate-dextrose [ACD] and saline), and 111In-tropolone (in ACD-plasma) as markers. Differences found between the 51Cr and 111In labels probably can be attributed to a variation in localization of the label on the cell and of renal handling of the free label after release. The mean platelet survival time with 51Cr was slightly longer than the survival time with both indium labels and showed a sex difference not seen with 111In-oxine. Protein-bound plasma 51Cr was lower than plasma 111In and remained constant throughout the study. Plasma 111In increased with time. For survival time calculations, no correction for free 51Cr is necessary, but correction should routinely be performed when 111In markers are used. Both 111In markers gave similar results with respect to platelet survival time. The somewhat more elaborate plasma labeling procedure with tropolone shows no measurable advantage over the original 111In-oxine method. 111In-tropolone labeling takes less time and maintains platelets in the physiologic environment of plasma during incubation. Biodistribution studies show no difference between the two 111In markers."
1236098,Koslo et al. 1986,Intrathecal bombesin-induced inhibition of gastrointestinal transit: requirement for an intact pituitary-adrenal axis,"The role of the pituitary-adrenal axis in the inhibition of gastrointestinal transit caused by intrathecal administration of bombesin was examined. Bombesin (0.3-10 micrograms) slowed transit by this route in a dose-related manner. Either hypophysectomy or adrenalectomy prevented the inhibition of gastrointestinal transit associated with bombesin (10 micrograms, i.th.). The inhibitory gut effects of this peptide were not prevented in sham-operated rats. Intrathecal bombesin-induced inhibition of gastrointestinal transit is thus dependent upon an intact pituitary-adrenal axis.","Intrathecal bombesin-induced inhibition of gastrointestinal transit: requirement for an intact pituitary-adrenal axis Abs: The role of the pituitary-adrenal axis in the inhibition of gastrointestinal transit caused by intrathecal administration of bombesin was examined. Bombesin (0.3-10 micrograms) slowed transit by this route in a dose-related manner. Either hypophysectomy or adrenalectomy prevented the inhibition of gastrointestinal transit associated with bombesin (10 micrograms, i.th.). The inhibitory gut effects of this peptide were not prevented in sham-operated rats. Intrathecal bombesin-induced inhibition of gastrointestinal transit is thus dependent upon an intact pituitary-adrenal axis."
1236097,Kawanishi et al. 1986,Mechanism of DNA cleavage induced by sodium chromate(VI) in the presence of hydrogen peroxide,"Reactivities of chromium compounds with DNA were investigated by the DNA sequencing technique using 32P 5'-end-labeled DNA fragments, and the reaction mechanism was investigated by ESR spectroscopy. Incubation of double-stranded DNA with sodium chromate(VI) plus hydrogen peroxide or potassium tetraperoxochromate(V) led to the cleavage at the position of every base, particularly of guanine. Even without piperidine, the formation of oligonucleotides was observed, suggesting the breakage of the deoxyribose-phosphate backbone. ESR studies using hydroxyl radical traps demonstrated that hydroxyl radical is generated both during the reaction of sodium chromate(VI) with hydrogen peroxide and the decomposition of potassium tetraperoxochromate(V), and that hydroxyl radical reacts significantly not only with mononucleotides but also with deoxyribose 5-phosphate. ESR studies using a singlet oxygen trap demonstrated that singlet oxygen is also generated both by the same reaction and decomposition, and reacts significantly with deoxyguanylate, but scarcely reacts with other mononucleotides. Furthermore, ESR studies suggested that tetraperoxochromate(V) is formed by the reaction of sodium chromate(VI) with hydrogen peroxide. These results indicate that sodium chromate(VI) reacts with hydrogen peroxide to form tetraperoxochromate(V), leading to the production of the hydroxyl radical, which causes every base alteration and deoxyribose-phosphate backbone breakage. In addition, sodium chromate(VI) plus hydrogen peroxide generates singlet oxygen, which subsequently oxidizes the guanine residue. The mechanism by which both hydroxyl radical and singlet oxygen are generated during the reaction of sodium chromate(VI) with hydrogen peroxide was presented. Finally, the possibility that this reaction may be one of the primary reactions of carcinogenesis induced by chromate(VI) is discussed.","Mechanism of DNA cleavage induced by sodium chromate(VI) in the presence of hydrogen peroxide Abs: Reactivities of chromium compounds with DNA were investigated by the DNA sequencing technique using 32P 5'-end-labeled DNA fragments, and the reaction mechanism was investigated by ESR spectroscopy. Incubation of double-stranded DNA with sodium chromate(VI) plus hydrogen peroxide or potassium tetraperoxochromate(V) led to the cleavage at the position of every base, particularly of guanine. Even without piperidine, the formation of oligonucleotides was observed, suggesting the breakage of the deoxyribose-phosphate backbone. ESR studies using hydroxyl radical traps demonstrated that hydroxyl radical is generated both during the reaction of sodium chromate(VI) with hydrogen peroxide and the decomposition of potassium tetraperoxochromate(V), and that hydroxyl radical reacts significantly not only with mononucleotides but also with deoxyribose 5-phosphate. ESR studies using a singlet oxygen trap demonstrated that singlet oxygen is also generated both by the same reaction and decomposition, and reacts significantly with deoxyguanylate, but scarcely reacts with other mononucleotides. Furthermore, ESR studies suggested that tetraperoxochromate(V) is formed by the reaction of sodium chromate(VI) with hydrogen peroxide. These results indicate that sodium chromate(VI) reacts with hydrogen peroxide to form tetraperoxochromate(V), leading to the production of the hydroxyl radical, which causes every base alteration and deoxyribose-phosphate backbone breakage. In addition, sodium chromate(VI) plus hydrogen peroxide generates singlet oxygen, which subsequently oxidizes the guanine residue. The mechanism by which both hydroxyl radical and singlet oxygen are generated during the reaction of sodium chromate(VI) with hydrogen peroxide was presented. Finally, the possibility that this reaction may be one of the primary reactions of carcinogenesis induced by chromate(VI) is discussed."
1236095,Viau et al. 1986,Determination of rat beta 2-microglobulin in urine and in serum. I. Development of an immunoassay based on latex particles agglutination,"Rat beta 2-microglobulin has been isolated from the urine of rats pretreated with sodium chromate. The purified protein was used to raise antisera in two rabbits. Treatment of the antisera with ammonium sulphate followed by gel chromatography led to an immunoglobulin fraction which was used to coat latex particles by physical adsorption. The latex suspension was used in an automated system including an optical particle counter to analyse the protein in serum, urine and cerebrospinal fluid. Serum contains 5.8 mg of beta 2-microglobulin/l, of which 33% is found as a 55000 dalton complex while 66% is present as the 'free' protein. The daily urinary excretion of beta 2-microglobulin in females is about 2 micrograms of which 7% is found to be a 65000-dalton complex while 92% is the free protein. From this, it can be calculated that the fractional urinary excretion of beta 2-microglobulin is about 0.03%. The cerebrospinal fluid contains about 1 mg of beta 2-microglobulin/l. Preliminary tests also suggest that the method can be adapted for non-automated turbidimetric detection. In the automated assay, the within- and between-assay coefficients of variation are less than 10% for the three biological fluids tested. The analytical recovery in the urine is 93%. In urine, beta 2-microglobulin undergoes proteolytic degradation at pH below 6. This does not represent a serious drawback to its use as a sensitive index of tubular function since in most experimental circumstances, rats excrete urine with a pH above this value.","Determination of rat beta 2-microglobulin in urine and in serum. I. Development of an immunoassay based on latex particles agglutination Abs: Rat beta 2-microglobulin has been isolated from the urine of rats pretreated with sodium chromate. The purified protein was used to raise antisera in two rabbits. Treatment of the antisera with ammonium sulphate followed by gel chromatography led to an immunoglobulin fraction which was used to coat latex particles by physical adsorption. The latex suspension was used in an automated system including an optical particle counter to analyse the protein in serum, urine and cerebrospinal fluid. Serum contains 5.8 mg of beta 2-microglobulin/l, of which 33% is found as a 55000 dalton complex while 66% is present as the 'free' protein. The daily urinary excretion of beta 2-microglobulin in females is about 2 micrograms of which 7% is found to be a 65000-dalton complex while 92% is the free protein. From this, it can be calculated that the fractional urinary excretion of beta 2-microglobulin is about 0.03%. The cerebrospinal fluid contains about 1 mg of beta 2-microglobulin/l. Preliminary tests also suggest that the method can be adapted for non-automated turbidimetric detection. In the automated assay, the within- and between-assay coefficients of variation are less than 10% for the three biological fluids tested. The analytical recovery in the urine is 93%. In urine, beta 2-microglobulin undergoes proteolytic degradation at pH below 6. This does not represent a serious drawback to its use as a sensitive index of tubular function since in most experimental circumstances, rats excrete urine with a pH above this value."
1236094,Viau et al. 1986,Determination of rat beta 2-microglobulin in urine and in serum. II. Application of its urinary measurement to selected nephrotoxicity models,"beta 2-microglobulin (beta 2-m) was measured in the urine of rats by a specific immunoassay based on latex particles agglutination. The excretion of this protein was compared to the excretion of the enzyme beta-N-acetyl-D-glucosaminidase (NAG), albumin and amino acids in rats treated with either a single dose of sodium chromate (5 and 10 mg kg-1), repeated doses of gentamicin (5 and 20 mg kg-1), or cadmium (1 mg kg-1), and in aging rats (from 2 to 20 months). All treatments resulted in an early increased excretion of beta 2-m indicative of functional alterations of the proximal tubular cells. An increased NAG excretion was observed only at the highest dose of chromate and in the cadmium model but the relative increases of beta 2-m were much larger (up to 200 times the control values against four times the control values for NAG). From 2 to 20 months of age, urinary beta 2-m increases by a factor of four. Aminoacids excretion showed little sensitivity in the various models. Albumin showed little variations in purely tubular or in the tubular phase of renal injury but the chronic progressive nephrosis of aging rats caused a 40-fold increase in its excretion between 2 and 20 months of age. Therefore urinary beta 2-m, albumin and albumin/beta 2-m ratio provide useful tools in the assessment of nephrotoxicity and of its mechanisms in various experimental models.","Determination of rat beta 2-microglobulin in urine and in serum. II. Application of its urinary measurement to selected nephrotoxicity models Abs: beta 2-microglobulin (beta 2-m) was measured in the urine of rats by a specific immunoassay based on latex particles agglutination. The excretion of this protein was compared to the excretion of the enzyme beta-N-acetyl-D-glucosaminidase (NAG), albumin and amino acids in rats treated with either a single dose of sodium chromate (5 and 10 mg kg-1), repeated doses of gentamicin (5 and 20 mg kg-1), or cadmium (1 mg kg-1), and in aging rats (from 2 to 20 months). All treatments resulted in an early increased excretion of beta 2-m indicative of functional alterations of the proximal tubular cells. An increased NAG excretion was observed only at the highest dose of chromate and in the cadmium model but the relative increases of beta 2-m were much larger (up to 200 times the control values against four times the control values for NAG). From 2 to 20 months of age, urinary beta 2-m increases by a factor of four. Aminoacids excretion showed little sensitivity in the various models. Albumin showed little variations in purely tubular or in the tubular phase of renal injury but the chronic progressive nephrosis of aging rats caused a 40-fold increase in its excretion between 2 and 20 months of age. Therefore urinary beta 2-m, albumin and albumin/beta 2-m ratio provide useful tools in the assessment of nephrotoxicity and of its mechanisms in various experimental models."
1236093,Elfers et al. 1986,"Alterations in calcium, phosphorus and C-terminal parathyroid hormone levels in equine acute renal disease","The changes in serum and urinary levels of calcium and phosphorus and serum parathyroid hormone (PTH) were studied during controlled, chemically induced, acute renal disease in 4 ponies. There was an initial rise in daily urinary calcium and hydroxyproline excretion in 2 ponies which may have indicated increased bone resorption. Mild hypercalcemia, hypophosphatemia and elevated C-terminal PTH levels were associated with oliguria. Total daily urinary excretion of calcium and phosphorus decreased as oliguria developed. The levels of C-terminal PTH were increased in all four animals. This appears to have been related to their diminished renal function in that C-terminal fragments of intact PTH (which require functioning kidneys in order to be cleared) were probably being accumulated. Although there was no evidence with regard to an actual increase in PTH secretion, prolongation of intact PTH half-life due to renal tubular damage may have contributed to the development of hypercalcemia.","Alterations in calcium, phosphorus and C-terminal parathyroid hormone levels in equine acute renal disease Abs: The changes in serum and urinary levels of calcium and phosphorus and serum parathyroid hormone (PTH) were studied during controlled, chemically induced, acute renal disease in 4 ponies. There was an initial rise in daily urinary calcium and hydroxyproline excretion in 2 ponies which may have indicated increased bone resorption. Mild hypercalcemia, hypophosphatemia and elevated C-terminal PTH levels were associated with oliguria. Total daily urinary excretion of calcium and phosphorus decreased as oliguria developed. The levels of C-terminal PTH were increased in all four animals. This appears to have been related to their diminished renal function in that C-terminal fragments of intact PTH (which require functioning kidneys in order to be cleared) were probably being accumulated. Although there was no evidence with regard to an actual increase in PTH secretion, prolongation of intact PTH half-life due to renal tubular damage may have contributed to the development of hypercalcemia."
1236091,Ellis and  Freeman 1986,Dermatitis due to chromate in cement. Part I. Chromate content of cement in Australia,,Dermatitis due to chromate in cement. Part I. Chromate content of cement in Australia Abs: 
1236089,Sewell et al. 1986,Ethanol-induced cell damage in cultured rat antral mucosa assessed by chromium-51 release,"We have developed an in vitro method for studying ethanol-induced injury to gastric mucosa using organ culture of rat antrum. Cell damage was assessed by measurement of the release of [51Cr]sodium chromate from preloaded cells, a method adapted from a standard immunologic technique. This system provided rapid and highly reproducible quantitation of tissue injury as assessed by 51Cr release into the culture medium. The threshold concentration for ethanol-induced damage was between 10 and 15% v/v, similar to in vivo thresholds observed by others. 51Cr release could also be induced by very short exposure to ethanol (5-15 min), and then continued despite ethanol removal. Interestingly, after continuous ethanol exposure, a plateau of maximum 51Cr release was reached 60 min after exposure to ethanol over the concentration range 20-50%, suggesting tissue adaptation to ethanol damage. This organ culture system, which allows precise control of experimental conditions, may be useful for studying mechanisms of gastric mucosal injury and protection.","Ethanol-induced cell damage in cultured rat antral mucosa assessed by chromium-51 release Abs: We have developed an in vitro method for studying ethanol-induced injury to gastric mucosa using organ culture of rat antrum. Cell damage was assessed by measurement of the release of [51Cr]sodium chromate from preloaded cells, a method adapted from a standard immunologic technique. This system provided rapid and highly reproducible quantitation of tissue injury as assessed by 51Cr release into the culture medium. The threshold concentration for ethanol-induced damage was between 10 and 15% v/v, similar to in vivo thresholds observed by others. 51Cr release could also be induced by very short exposure to ethanol (5-15 min), and then continued despite ethanol removal. Interestingly, after continuous ethanol exposure, a plateau of maximum 51Cr release was reached 60 min after exposure to ethanol over the concentration range 20-50%, suggesting tissue adaptation to ethanol damage. This organ culture system, which allows precise control of experimental conditions, may be useful for studying mechanisms of gastric mucosal injury and protection."
1236087,Goh et al. 1986,Chromate allergy: total chromium and hexavalent chromate in the air,"This is a study on atmospheric concentration of total chromium and hexavalent chromate and its role in chromate sensitivity. Air concentration of total chromium and hexavalent chromate in a construction factory, a busy city area, a suburban area, a residential area, and a heavy industrial area were measured by air sampling pumps. Hexavalent chromate was not detected in any sampled areas. Two (concreting areas) of 8 locations in the construction factory had total chromium of 0.2 and 2.3 micrograms/m3 in the atmosphere. It appeared that the atmospheric concentration of total chromium and hexavalent chromate was negligible. These findings indicate that unexplained chromate sensitivity, as so often seen in patients attending a contact dermatitis clinic, is not attributable to exposure to hexavalent chromate in the air.","Chromate allergy: total chromium and hexavalent chromate in the air Abs: This is a study on atmospheric concentration of total chromium and hexavalent chromate and its role in chromate sensitivity. Air concentration of total chromium and hexavalent chromate in a construction factory, a busy city area, a suburban area, a residential area, and a heavy industrial area were measured by air sampling pumps. Hexavalent chromate was not detected in any sampled areas. Two (concreting areas) of 8 locations in the construction factory had total chromium of 0.2 and 2.3 micrograms/m3 in the atmosphere. It appeared that the atmospheric concentration of total chromium and hexavalent chromate was negligible. These findings indicate that unexplained chromate sensitivity, as so often seen in patients attending a contact dermatitis clinic, is not attributable to exposure to hexavalent chromate in the air."
1236083,Goh and  Kwok 1986,Chromate allergy: chromate content of Asian cement,,Chromate allergy: chromate content of Asian cement Abs: 
1236082,Norseth 1986,The carcinogenicity of chromium and its salts,,The carcinogenicity of chromium and its salts Abs: 
1236080,Beevers and  Sloan 1986,Saltex dipstick evaluated for rapid estimation of chloride and sodium concentrations in urine,,Saltex dipstick evaluated for rapid estimation of chloride and sodium concentrations in urine Abs: 
1236077,Esko et al. 1986,Sulfate transport-deficient mutants of Chinese hamster ovary cells. Sulfation of glycosaminoglycans dependent on cysteine,"We isolated 59 Chinese hamster ovary cell mutants defective in 35SO4 incorporation into glycosaminoglycans. Thirty-five mutants incorporated [6-3H]glucosamine into glycosaminoglycans normally, suggesting that they were specifically impaired in sulfate incorporation. Cell hybridization studies revealed that the 35 mutants defined a unique complementation group. Pulse-labeling one of the mutants with 35SO4 showed that it possessed a defect in a saturable, 4-acetamido-4-isothiocyanostilbene-2,2'-disulfonic acid-sensitive transport system required for sulfate uptake. Despite the dramatic reduction in 35SO4 incorporation, the mutant synthesized sulfated heparan and chondroitin chains. Incubation of the mutant with [35S]cysteine resulted in the formation of 35SO4, which was subsequently incorporated into the glycosaminoglycans. Similar results were obtained when wild-type cells were incubated in sulfate-free growth medium containing [35S]cysteine, and isotope dilution analysis indicated that about 15 microM of sulfate was derived from cysteine catabolism. We also found that the sulfate transport deficiency rendered the mutant resistant to 5 microM sodium chromate, whereas wild-type cells did not divide under these conditions. However, the mutant also did not proliferate in medium containing 5 microM chromate when grown in the presence of wild-type cells, suggesting that chromate was transported through cell-cell contacts. Since co-cultivating sulfate transport-deficient mutants with mutants defective in xylosyltransferase or galactosyltransferase I partially restored 35SO4 incorporation into glycosaminoglycans, intercellular sulfate transport occurred as well. Therefore, the availability of sulfate for glycosaminoglycan synthesis depends on sulfate uptake, turnover of sulfur-containing amino acids, and sulfate transport between cells.","Sulfate transport-deficient mutants of Chinese hamster ovary cells. Sulfation of glycosaminoglycans dependent on cysteine Abs: We isolated 59 Chinese hamster ovary cell mutants defective in 35SO4 incorporation into glycosaminoglycans. Thirty-five mutants incorporated [6-3H]glucosamine into glycosaminoglycans normally, suggesting that they were specifically impaired in sulfate incorporation. Cell hybridization studies revealed that the 35 mutants defined a unique complementation group. Pulse-labeling one of the mutants with 35SO4 showed that it possessed a defect in a saturable, 4-acetamido-4-isothiocyanostilbene-2,2'-disulfonic acid-sensitive transport system required for sulfate uptake. Despite the dramatic reduction in 35SO4 incorporation, the mutant synthesized sulfated heparan and chondroitin chains. Incubation of the mutant with [35S]cysteine resulted in the formation of 35SO4, which was subsequently incorporated into the glycosaminoglycans. Similar results were obtained when wild-type cells were incubated in sulfate-free growth medium containing [35S]cysteine, and isotope dilution analysis indicated that about 15 microM of sulfate was derived from cysteine catabolism. We also found that the sulfate transport deficiency rendered the mutant resistant to 5 microM sodium chromate, whereas wild-type cells did not divide under these conditions. However, the mutant also did not proliferate in medium containing 5 microM chromate when grown in the presence of wild-type cells, suggesting that chromate was transported through cell-cell contacts. Since co-cultivating sulfate transport-deficient mutants with mutants defective in xylosyltransferase or galactosyltransferase I partially restored 35SO4 incorporation into glycosaminoglycans, intercellular sulfate transport occurred as well. Therefore, the availability of sulfate for glycosaminoglycan synthesis depends on sulfate uptake, turnover of sulfur-containing amino acids, and sulfate transport between cells."
1236069,Fioramonti et al. 1987,Action of T-2 toxin on gastrointestinal transit in mice: protective effect of an argillaceous compound,"Using sodium [51Cr]chromate as radiolabeled marker, gastrointestinal transit of a milk test meal was determined in mice receiving for 4 days T-2 toxin (1 mg/kg per day per os) alone or with a clay, smectite (2 g/kg per day), given according to four different procedures. Gastric emptying and small intestinal transit were significantly accelerated after the 1st T-2 administration and during the 4 days of treatment. When smectite was given together with the toxin with or without pretreatment by smectite alone for 2 days, the T-2 induced disturbances in gastrointestinal transit remained unchanged. A pretreatment by smectite for 4 days abolished the T-2 induced acceleration of gastric emptying but not of small intestinal transit. When T-2 was incubated with smectite for 24 h before oral administration, gastric emptying and small intestinal transit were not significantly accelerated.","Action of T-2 toxin on gastrointestinal transit in mice: protective effect of an argillaceous compound Abs: Using sodium [51Cr]chromate as radiolabeled marker, gastrointestinal transit of a milk test meal was determined in mice receiving for 4 days T-2 toxin (1 mg/kg per day per os) alone or with a clay, smectite (2 g/kg per day), given according to four different procedures. Gastric emptying and small intestinal transit were significantly accelerated after the 1st T-2 administration and during the 4 days of treatment. When smectite was given together with the toxin with or without pretreatment by smectite alone for 2 days, the T-2 induced disturbances in gastrointestinal transit remained unchanged. A pretreatment by smectite for 4 days abolished the T-2 induced acceleration of gastric emptying but not of small intestinal transit. When T-2 was incubated with smectite for 24 h before oral administration, gastric emptying and small intestinal transit were not significantly accelerated."
1236068,Bussolino et al. 1987,Measurement of phagocytosis utilizing [14C]cyanate-labelled human red cells and monocytes,"Human red cells were labelled with [14C]cyanate, non-oxidant, permeant reagent that binds irreversibly to amino groups in proteins. Cyanate did not modify GSH levels, nor glucose-6-phosphate dehydrogenase (G6PD) activity when added at the labelling concentration i.e. c. 0.5 mM. Phagocytes were human monocytes, isolated and plated on 16 mm diameter plastic wells. Each well was plated with 40-70 X 10(3) cells. Monocytes were quantified by DNA assay with the DNA intercalating fluorescent compound Hoechst 33,258. The basal phagocytic rate of normal red cells by monocytes was 0.34 +/- 0.21 red cell per monocyte. Treatment of normal red cells with 20 microM diamide, or 50-100 microM chromate enhanced this rate 10-15-fold. 10 microM diamide or chromate were sufficient to stimulate phagocytosis of G6PD-deficient (Mediterranean variant) red cells.","Measurement of phagocytosis utilizing [14C]cyanate-labelled human red cells and monocytes Abs: Human red cells were labelled with [14C]cyanate, non-oxidant, permeant reagent that binds irreversibly to amino groups in proteins. Cyanate did not modify GSH levels, nor glucose-6-phosphate dehydrogenase (G6PD) activity when added at the labelling concentration i.e. c. 0.5 mM. Phagocytes were human monocytes, isolated and plated on 16 mm diameter plastic wells. Each well was plated with 40-70 X 10(3) cells. Monocytes were quantified by DNA assay with the DNA intercalating fluorescent compound Hoechst 33,258. The basal phagocytic rate of normal red cells by monocytes was 0.34 +/- 0.21 red cell per monocyte. Treatment of normal red cells with 20 microM diamide, or 50-100 microM chromate enhanced this rate 10-15-fold. 10 microM diamide or chromate were sufficient to stimulate phagocytosis of G6PD-deficient (Mediterranean variant) red cells."
1236066,Young and  Houwing 1987,Patch test results with standard allergens over a decade,The results of 10 years of patch testing with standard allergens are reported. An increase of sensitivity was found in nickel. Sensitivity to chromate had decreased. Sex and age differences in the incidence of allergy to metals were analysed. Nickel allergy appeared to be more common among women and was of most importance in the younger age groups.,Patch test results with standard allergens over a decade Abs: The results of 10 years of patch testing with standard allergens are reported. An increase of sensitivity was found in nickel. Sensitivity to chromate had decreased. Sex and age differences in the incidence of allergy to metals were analysed. Nickel allergy appeared to be more common among women and was of most importance in the younger age groups.
1236063,Kucharz and  Sierakowski 1987,Immunotoxicity of chromium compounds: effect of sodium dichromate on the T cell activation in vitro,,Immunotoxicity of chromium compounds: effect of sodium dichromate on the T cell activation in vitro Abs: 
1236062,De Flora et al. 1987,Pulmonary metabolism of mutagens and its relationship with lung cancer and smoking habits,"The S-12 fractions of lung peripheral parenchyma obtained from 80 male individuals, aged 17-71 years, were assayed as blind samples for the ability either to convert promutagens into bacterial mutagens or to decrease the potency of direct-acting mutagens in the Ames reversion test. In this system, lung preparations were completely ineffective in activating an N-nitroso compound (i.e., N-nitrosomorpholine) and polycyclic aromatic hydrocarbons [i.e., 3-methylcholanthrene and benzo(a)pyrene] or their metabolites [i.e., 3-hydroxy-benzo(a)pyrene and benzo(a)pyrene-trans-7,8-diol]. They yielded a borderline and sporadic activation of a cigarette smoke condensate, and a weak but frequent activation of an aromatic amine (i.e., 2-aminofluorene), of a heterocyclic amine (i.e., 2-amino-3,4-dimethylimidazo[4,5-f] and of a diamide (i.e., cyclophosphamide). The pulmonary metabolism was more oriented in the sense of detoxification, as shown by the consistent decrease of potency of direct-acting mutagens, including a metal (i.e., sodium dichromate), an acridine and nitrogen mustard derivative (i.e., 2-methoxy-6-chloro-9-[3-(2-chloromethyl)aminopropylamino]acridine or ICR 191), an epoxide (i.e., epichlorohydrin) and an N-oxide (i.e., 4-nitroquinoline-N-oxide). As assessed by means of a numerical score quantifying the variation of mutagenicity, a marked interindividual variability (up to 20-fold) was detected in the ability of lung specimens to affect the mutagenicity of test compounds. Such variability was not significantly related to the protein concentration of S-12 fractions, nor to the age of the patients under scrutiny, who during hospitalization were on normal institutional diets and did not receive any special drug treatment. The only significant difference between 20 noncancer and 60 lung cancer patients, irrespective of the histological type, was a decreased activation of cyclophosphamide in the latter group. Probably due to the high prevalence of smokers among lung cancer patients, a significantly decreased activation of cyclophosphamide was also observed in the group of smokers. Smoking habits were associated with a stimulation of detoxifying mechanisms which, in agreement with the results of a previous study with human alveolar macrophages (F. L. Petrilli et al., J. Clin. Invest., 77:1917-1924, 1986), was significant in the case of sodium dichromate. Such effect was further enhanced by considering only individuals smoking during the last 24 h before collecting lung specimens, and under these conditions it became significant also for ICR 191.(ABSTRACT TRUNCATED AT 250 WORDS)","Pulmonary metabolism of mutagens and its relationship with lung cancer and smoking habits Abs: The S-12 fractions of lung peripheral parenchyma obtained from 80 male individuals, aged 17-71 years, were assayed as blind samples for the ability either to convert promutagens into bacterial mutagens or to decrease the potency of direct-acting mutagens in the Ames reversion test. In this system, lung preparations were completely ineffective in activating an N-nitroso compound (i.e., N-nitrosomorpholine) and polycyclic aromatic hydrocarbons [i.e., 3-methylcholanthrene and benzo(a)pyrene] or their metabolites [i.e., 3-hydroxy-benzo(a)pyrene and benzo(a)pyrene-trans-7,8-diol]. They yielded a borderline and sporadic activation of a cigarette smoke condensate, and a weak but frequent activation of an aromatic amine (i.e., 2-aminofluorene), of a heterocyclic amine (i.e., 2-amino-3,4-dimethylimidazo[4,5-f] and of a diamide (i.e., cyclophosphamide). The pulmonary metabolism was more oriented in the sense of detoxification, as shown by the consistent decrease of potency of direct-acting mutagens, including a metal (i.e., sodium dichromate), an acridine and nitrogen mustard derivative (i.e., 2-methoxy-6-chloro-9-[3-(2-chloromethyl)aminopropylamino]acridine or ICR 191), an epoxide (i.e., epichlorohydrin) and an N-oxide (i.e., 4-nitroquinoline-N-oxide). As assessed by means of a numerical score quantifying the variation of mutagenicity, a marked interindividual variability (up to 20-fold) was detected in the ability of lung specimens to affect the mutagenicity of test compounds. Such variability was not significantly related to the protein concentration of S-12 fractions, nor to the age of the patients under scrutiny, who during hospitalization were on normal institutional diets and did not receive any special drug treatment. The only significant difference between 20 noncancer and 60 lung cancer patients, irrespective of the histological type, was a decreased activation of cyclophosphamide in the latter group. Probably due to the high prevalence of smokers among lung cancer patients, a significantly decreased activation of cyclophosphamide was also observed in the group of smokers. Smoking habits were associated with a stimulation of detoxifying mechanisms which, in agreement with the results of a previous study with human alveolar macrophages (F. L. Petrilli et al., J. Clin. Invest., 77:1917-1924, 1986), was significant in the case of sodium dichromate. Such effect was further enhanced by considering only individuals smoking during the last 24 h before collecting lung specimens, and under these conditions it became significant also for ICR 191.(ABSTRACT TRUNCATED AT 250 WORDS)"
1236060,Molina and  Abell 1987,An ion chromatographic method for insoluble chromates in paint aerosol,"Potential exposure to Cr(VI) extends to over a million U.S. workers in the plating, paint, steel, tanning and chrome ore processing industries. Historically, Cr(VI) exposure has been monitored using a colorimetric method. This colorimetric method requires acidification of the sample for color development, a step that could cause reduction of Cr(VI) to Cr(III), thus underestimating the Cr(VI) content of the sample. A new method of analysis has been developed that uses ion chromatography (IC) for the measurement and which does not require acidification of the sample. In this method, the same extraction solution of hot 2% NaOH and 3% Na2CO3 as used in the earlier methods is used to dissolve both soluble and insoluble chromates (e.g., PbCrO4, ZnCrO4 and BaCrO4), but it can be carried through the method with only a dilution step before sample injection. Therefore, this method has the advantage of minimizing the potential for Cr(VI) loss by reduction. Another advantage is provided by the IC measurement step, which is not interfered with by colored samples that may affect the colorimetric method. The new method was tested with filter samples of paint aerosol containing PbCrO4 and ZnCrO4. Complete extraction of Cr(VI) from the filter samples was verified by comparison to an independent method in which the filter was completely ashed and analyzed by inductively coupled plasma-atomic emission spectroscopy method. Nothing in the paint samples interfered with the Cr(VI) measurement, nor did five common anions used in a separate test. The method had the sensitivity needed for monitoring at the ACGIH TLV of 0.05 mg Cr(VI)/m3.","An ion chromatographic method for insoluble chromates in paint aerosol Abs: Potential exposure to Cr(VI) extends to over a million U.S. workers in the plating, paint, steel, tanning and chrome ore processing industries. Historically, Cr(VI) exposure has been monitored using a colorimetric method. This colorimetric method requires acidification of the sample for color development, a step that could cause reduction of Cr(VI) to Cr(III), thus underestimating the Cr(VI) content of the sample. A new method of analysis has been developed that uses ion chromatography (IC) for the measurement and which does not require acidification of the sample. In this method, the same extraction solution of hot 2% NaOH and 3% Na2CO3 as used in the earlier methods is used to dissolve both soluble and insoluble chromates (e.g., PbCrO4, ZnCrO4 and BaCrO4), but it can be carried through the method with only a dilution step before sample injection. Therefore, this method has the advantage of minimizing the potential for Cr(VI) loss by reduction. Another advantage is provided by the IC measurement step, which is not interfered with by colored samples that may affect the colorimetric method. The new method was tested with filter samples of paint aerosol containing PbCrO4 and ZnCrO4. Complete extraction of Cr(VI) from the filter samples was verified by comparison to an independent method in which the filter was completely ashed and analyzed by inductively coupled plasma-atomic emission spectroscopy method. Nothing in the paint samples interfered with the Cr(VI) measurement, nor did five common anions used in a separate test. The method had the sensitivity needed for monitoring at the ACGIH TLV of 0.05 mg Cr(VI)/m3."
1236059,Sugiyama et al. 1987,"Effects of vitamin E, vitamin B2 and selenite on DNA single strand breaks induced by sodium chromate (VI)","The effects of vitamin E, vitamin B2 and selenite on DNA single strand breaks induced by Na2CrO4 were examined by alkaline elution. Incubation of Chinese hamster V-79 cells with alpha-tocopherol succinate (vitamin E) for 24 h prior to exposure to Na2CrO4 resulted in a decrease of DNA breaks produced by this compound. However, similar pretreatment with riboflavin (vitamin B2) or Na2SeO3 resulted in an enhanced formation of breaks induced by Na2CrO4. Pretreatment with Na2SeO3 resulted in increased levels of glutathione in these cells while levels of glutathione remained the same with vitamin E or vitamin B2. These results suggest that Na2CrO4 induced DNA breaks appear to be mediated by the formation of free radicals and/or cellular reductive metabolism.","Effects of vitamin E, vitamin B2 and selenite on DNA single strand breaks induced by sodium chromate (VI) Abs: The effects of vitamin E, vitamin B2 and selenite on DNA single strand breaks induced by Na2CrO4 were examined by alkaline elution. Incubation of Chinese hamster V-79 cells with alpha-tocopherol succinate (vitamin E) for 24 h prior to exposure to Na2CrO4 resulted in a decrease of DNA breaks produced by this compound. However, similar pretreatment with riboflavin (vitamin B2) or Na2SeO3 resulted in an enhanced formation of breaks induced by Na2CrO4. Pretreatment with Na2SeO3 resulted in increased levels of glutathione in these cells while levels of glutathione remained the same with vitamin E or vitamin B2. These results suggest that Na2CrO4 induced DNA breaks appear to be mediated by the formation of free radicals and/or cellular reductive metabolism."
1236058,Akerström et al. 1987,"Structural relationship between alpha 1-microglobulin from man, guinea-pig, rat and rabbit","Rabbit alpha 1-microglobulin was purified from the urine of sodium-chromate-treated animals by the use of gel chromatography on Sephadex G-100, affinity chromatography on concanavalin-A--Sepharose and ion-exchange chromatography on DEAE-Sephadex. Rabbit alpha 1-microglobulin had a molecular mass of 25.6 kDa on SDS/polyacrylamide gel electrophoresis. Alpha 1-microglobulin has previously been purified from the urine of humans, guinea-pigs and rats by similar methods, and the molecular masses of the four homologues were compared by SDS/polyacrylamide gel electrophoresis and gel chromatography in a denaturing medium. By these two methods the human homologue was 6 kDa and 3 kDa larger, respectively, than the other three proteins. Endoglycosidase F digestion of alpha 1-microglobulin, followed by SDS/polyacrylamide gel electrophoresis, revealed three protein bands in the human alpha 1-microglobulin sample, and only two bands in guinea-pig, rat and rabbit alpha 1-microglobulin, with a gap between each band of 2.6--2.9 kDa. The amino-terminal amino acid sequences of the four homologues were determined and between 72% and 81% homology was seen. The five amino-terminal amino acids present in the other species were missing in guinea-pig alpha 1-microglobulin. Our results indicate that human alpha 1-microglobulin is substituted with two N-linked oligosaccharides, while only one is attached to each of the other alpha 1-microglobulins, and that the extra glycosylamine-linked oligosaccharide in the human protein is attached to asparagine in position 17. Finally it is shown that all four homologues inhibit antigen stimulation of human lymphocytes, a finding which is consistent with our previous suggestion that the N-linked oligosaccharides carry the immunosuppressive activity of alpha 1-microglobulin.","Structural relationship between alpha 1-microglobulin from man, guinea-pig, rat and rabbit Abs: Rabbit alpha 1-microglobulin was purified from the urine of sodium-chromate-treated animals by the use of gel chromatography on Sephadex G-100, affinity chromatography on concanavalin-A--Sepharose and ion-exchange chromatography on DEAE-Sephadex. Rabbit alpha 1-microglobulin had a molecular mass of 25.6 kDa on SDS/polyacrylamide gel electrophoresis. Alpha 1-microglobulin has previously been purified from the urine of humans, guinea-pigs and rats by similar methods, and the molecular masses of the four homologues were compared by SDS/polyacrylamide gel electrophoresis and gel chromatography in a denaturing medium. By these two methods the human homologue was 6 kDa and 3 kDa larger, respectively, than the other three proteins. Endoglycosidase F digestion of alpha 1-microglobulin, followed by SDS/polyacrylamide gel electrophoresis, revealed three protein bands in the human alpha 1-microglobulin sample, and only two bands in guinea-pig, rat and rabbit alpha 1-microglobulin, with a gap between each band of 2.6--2.9 kDa. The amino-terminal amino acid sequences of the four homologues were determined and between 72% and 81% homology was seen. The five amino-terminal amino acids present in the other species were missing in guinea-pig alpha 1-microglobulin. Our results indicate that human alpha 1-microglobulin is substituted with two N-linked oligosaccharides, while only one is attached to each of the other alpha 1-microglobulins, and that the extra glycosylamine-linked oligosaccharide in the human protein is attached to asparagine in position 17. Finally it is shown that all four homologues inhibit antigen stimulation of human lymphocytes, a finding which is consistent with our previous suggestion that the N-linked oligosaccharides carry the immunosuppressive activity of alpha 1-microglobulin."
1236057,Sparrow et al. 1988,The effect of sodium chromate pretreatment on mercuric chloride-induced nephrotoxicity,"Sodium chromate (20 mg/kg, s.c.), which in male rats inflicted necrotic damage mainly in the P1 region (proximal part of the proximal convoluted tubules), protected against proximal tubular necrosis induced by 0.5 or 3.0 mg Hg2+/kg in the P2 (distal part of the proximal convoluted tubules) and P3 (pars recta part of the proximal tubules) regions. Histochemical staining for mercury indicated that chromate increased mercury deposition in those cells of the P1 region which were unaffected by chromate (had intact brush border) but did not decrease mercury deposition in the most severely affected P3 region. Chromate pretreatment actually increased mercury deposition in the kidneys of animals killed 24 h after the injection of 0.5 mg Hg2+. The protective effect was mutual. Cellular proliferation and fibrosis observed 4-5 days after chromate were prevented by injecting 0.5 mg Hg2+/kg 3 days after chromate treatment.","The effect of sodium chromate pretreatment on mercuric chloride-induced nephrotoxicity Abs: Sodium chromate (20 mg/kg, s.c.), which in male rats inflicted necrotic damage mainly in the P1 region (proximal part of the proximal convoluted tubules), protected against proximal tubular necrosis induced by 0.5 or 3.0 mg Hg2+/kg in the P2 (distal part of the proximal convoluted tubules) and P3 (pars recta part of the proximal tubules) regions. Histochemical staining for mercury indicated that chromate increased mercury deposition in those cells of the P1 region which were unaffected by chromate (had intact brush border) but did not decrease mercury deposition in the most severely affected P3 region. Chromate pretreatment actually increased mercury deposition in the kidneys of animals killed 24 h after the injection of 0.5 mg Hg2+. The protective effect was mutual. Cellular proliferation and fibrosis observed 4-5 days after chromate were prevented by injecting 0.5 mg Hg2+/kg 3 days after chromate treatment."
1236056,Appenroth and  Bräunlich 1988,Age dependent differences in sodium dichromate nephrotoxicity in rats,Investigations were performed on 10- and 55-day-old female Wistar rats. 1 or 2 mg sodium dichromate/100 g b. m. were administered subcutaneously. Urine was collected for 1 hour at different times after dichromate injection. Total urinary protein as well as some protein fractions (high and low molecular weight proteins as well as albumin) were determined. In adult rats dose dependence of nephrotoxicity was found concerning the extent and duration of renal damage. Separation of proteins gave an insight into the location of injury. At the beginning and in the recovery phase preferentially tubular damage was found. The peak of damage is characterized by additional glomerular disturbances. Young rats are much less susceptible to dichromate than adult rats are. Possible reasons are discussed.,Age dependent differences in sodium dichromate nephrotoxicity in rats Abs: Investigations were performed on 10- and 55-day-old female Wistar rats. 1 or 2 mg sodium dichromate/100 g b. m. were administered subcutaneously. Urine was collected for 1 hour at different times after dichromate injection. Total urinary protein as well as some protein fractions (high and low molecular weight proteins as well as albumin) were determined. In adult rats dose dependence of nephrotoxicity was found concerning the extent and duration of renal damage. Separation of proteins gave an insight into the location of injury. At the beginning and in the recovery phase preferentially tubular damage was found. The peak of damage is characterized by additional glomerular disturbances. Young rats are much less susceptible to dichromate than adult rats are. Possible reasons are discussed.
1236049,Koutras et al. 1964,STUDIES ON CHROMATED ERYTHROCYTES. EFFECT OF SODIUM CHROMATE ON ERYTHROCYTE GLUTATHIONE REDUCTASE,"The effect of sodium-chromate (7775113) on the activities of human erythrocyte enzymes was studied in vitro. There was no effect on the activities of the enzymes of the glycolytic pathway, on those of the pentose-phosphate pathway which were studied, or of acetylcholinesterase and glyoxalase. Concentrations of chromate of 5 to 25 micrograms of chromium (7440473) per milliliter of blood produced major inhibition of erythrocyte glutathione reductase. The inhibition was induced by hexavalent chromate ion only; trivalent chromic cation had no inhibitory effect.","STUDIES ON CHROMATED ERYTHROCYTES. EFFECT OF SODIUM CHROMATE ON ERYTHROCYTE GLUTATHIONE REDUCTASE Abs: The effect of sodium-chromate (7775113) on the activities of human erythrocyte enzymes was studied in vitro. There was no effect on the activities of the enzymes of the glycolytic pathway, on those of the pentose-phosphate pathway which were studied, or of acetylcholinesterase and glyoxalase. Concentrations of chromate of 5 to 25 micrograms of chromium (7440473) per milliliter of blood produced major inhibition of erythrocyte glutathione reductase. The inhibition was induced by hexavalent chromate ion only; trivalent chromic cation had no inhibitory effect."
1236035,Balazs et al. 1963,RENAL TESTS IN TOXICITY STUDIES ON RATS,"Renal tests for toxicity studies were investigated in rats. Wistar-rats were given single doses of 7.5 to 25 milligrams per kilogram (mg/kg) sodium-chromate (7775113), 0.9 to 25mg/kg uranyl-nitrate (10102064), and 0.38 to 0.75mg/kg mercuric-chloride (7487947) to induce acute renal tubular damage. After 24 to 48 hours, urine was collected for urinalysis and urinary glutamic-oxaloacetic-transaminase (GOT) measurements. All rats had urine collected for renal tests. Blood was taken and rats were killed for kidney histology. Urinary protein, glucose, and pH were estimated. Specific gravity was measured. Urine volume and pH were not affected by treatment. The highest doses of the three nephrotoxins caused widespread necrosis with all renal test values significantly altered; the middle dose significantly influenced all renal values except for blood urea nitrogen. High doses of uranyl-nitrate had only GOT distinguishing between the 6.0mg/kg and 1.8mg/kg dose. The high dose of 0.75mg/kg mercuric-chloride caused a marked increase in GOT. Low dose sodium-chromate producing only slight tubular injury was identified only by early concentration tests; low dose uranyl-nitrate produced more pronounced lesions. Low dose mercuric-chloride produced tubular dilatation and low grade injury. GOT gave the best graded response. The authors conclude that GOT is a good indicator for qualifying renal damage.","RENAL TESTS IN TOXICITY STUDIES ON RATS Abs: Renal tests for toxicity studies were investigated in rats. Wistar-rats were given single doses of 7.5 to 25 milligrams per kilogram (mg/kg) sodium-chromate (7775113), 0.9 to 25mg/kg uranyl-nitrate (10102064), and 0.38 to 0.75mg/kg mercuric-chloride (7487947) to induce acute renal tubular damage. After 24 to 48 hours, urine was collected for urinalysis and urinary glutamic-oxaloacetic-transaminase (GOT) measurements. All rats had urine collected for renal tests. Blood was taken and rats were killed for kidney histology. Urinary protein, glucose, and pH were estimated. Specific gravity was measured. Urine volume and pH were not affected by treatment. The highest doses of the three nephrotoxins caused widespread necrosis with all renal test values significantly altered; the middle dose significantly influenced all renal values except for blood urea nitrogen. High doses of uranyl-nitrate had only GOT distinguishing between the 6.0mg/kg and 1.8mg/kg dose. The high dose of 0.75mg/kg mercuric-chloride caused a marked increase in GOT. Low dose sodium-chromate producing only slight tubular injury was identified only by early concentration tests; low dose uranyl-nitrate produced more pronounced lesions. Low dose mercuric-chloride produced tubular dilatation and low grade injury. GOT gave the best graded response. The authors conclude that GOT is a good indicator for qualifying renal damage."
1236034,Poppell et al. 1963,EFFECT OF ASCORBIC ACID IN VIVO ON LABELING OF RED CELLS BY RADIOACTIVE SODIUM CHROMATE,,EFFECT OF ASCORBIC ACID IN VIVO ON LABELING OF RED CELLS BY RADIOACTIVE SODIUM CHROMATE Abs: 
1236033,Borun 1963,"Some differences in erythrocyte composition and uptake of radioactive potassium, sodium, chromate, and triiodothyronine associated with in vivo aging",,"Some differences in erythrocyte composition and uptake of radioactive potassium, sodium, chromate, and triiodothyronine associated with in vivo aging Abs: "
1236021,Wahlberg and  Skog 1963,The percutaneous absorption of sodium chromate (51Cr) in the guinea pig,,The percutaneous absorption of sodium chromate (51Cr) in the guinea pig Abs: 
1236014,Vincent 1962,Viability of Ehrlich ascites tumour cells exposed to sodium chromate labelled with chromium-51,,Viability of Ehrlich ascites tumour cells exposed to sodium chromate labelled with chromium-51 Abs: 
1236013,Samitz et al. 1962,Studies on the prevention of injurious effects of chromates in industry,"The usefulness of an antichrome reagent in the prevention and treatment of systemic intoxication, allergic dermatitis and skin ulcers due to chromates was studied in laboratory animals and printing and lithography workers (SIC-2752). Young albino-rats were given potassium-chromate (7789006) solutions containing 25 milligrams per milliliter (mg/ml) hexavalent-chromium (18540299), chromic-chloride (10025737), or 25mg/ml trivalent-chromium (16065831). Some rats were given ascorbic-acid at 200mg/ml as an antidote at different times after chromium. An antichrome reagent of two parts sodium-pyrosulfite (7681574) to one part of tartaric-acid (87694), one part of glucose (50997), and one part of ammonium-chloride (12125029) was developed for protection against allergic dermatitis due to chromates. Workers in contact with chromates in printing and lithography were advised to soak their hands in solutions of these reagents or ascorbic-acid after contact with chromates. Tests of hexavalent-chromium on the skin were made after use. Chrome ulcers were induced in guinea-pigs with hexavalent-chromium. The antichrome reagent with sodium-pyrosulfite was used with tissues exposed to hexavalent-chromium sufficient to cause ulcers. Ascorbic-acid prevented hexavalent-chromium poisoning in rats when given before the stomach emptied. Trivalent-chromium had no toxic effect and caused no pathological changes. THe hands of printing and lithography workers showed positive results for hexavalent-chromium after work. After soaking in either antichrome solution, tests became negative. Many workers objected to the odor of the solution. The antichrome preparation had limited effects in-vivo on ulcer formation. Prompt washing after application of chromates did reduce ulcer formation. The authors conclude that prompt washing with antichrome solutions can inhibit action of chromates on skin. An antichrome ointment might protect against nasal ulcers. Toxicity of ingested chromium can also be reduced.","Studies on the prevention of injurious effects of chromates in industry Abs: The usefulness of an antichrome reagent in the prevention and treatment of systemic intoxication, allergic dermatitis and skin ulcers due to chromates was studied in laboratory animals and printing and lithography workers (SIC-2752). Young albino-rats were given potassium-chromate (7789006) solutions containing 25 milligrams per milliliter (mg/ml) hexavalent-chromium (18540299), chromic-chloride (10025737), or 25mg/ml trivalent-chromium (16065831). Some rats were given ascorbic-acid at 200mg/ml as an antidote at different times after chromium. An antichrome reagent of two parts sodium-pyrosulfite (7681574) to one part of tartaric-acid (87694), one part of glucose (50997), and one part of ammonium-chloride (12125029) was developed for protection against allergic dermatitis due to chromates. Workers in contact with chromates in printing and lithography were advised to soak their hands in solutions of these reagents or ascorbic-acid after contact with chromates. Tests of hexavalent-chromium on the skin were made after use. Chrome ulcers were induced in guinea-pigs with hexavalent-chromium. The antichrome reagent with sodium-pyrosulfite was used with tissues exposed to hexavalent-chromium sufficient to cause ulcers. Ascorbic-acid prevented hexavalent-chromium poisoning in rats when given before the stomach emptied. Trivalent-chromium had no toxic effect and caused no pathological changes. THe hands of printing and lithography workers showed positive results for hexavalent-chromium after work. After soaking in either antichrome solution, tests became negative. Many workers objected to the odor of the solution. The antichrome preparation had limited effects in-vivo on ulcer formation. Prompt washing after application of chromates did reduce ulcer formation. The authors conclude that prompt washing with antichrome solutions can inhibit action of chromates on skin. An antichrome ointment might protect against nasal ulcers. Toxicity of ingested chromium can also be reduced."
1235993,Suzuki 1988,Valence states of plasma chromium in rats after intraperitoneal administration of sodium chromate,,Valence states of plasma chromium in rats after intraperitoneal administration of sodium chromate Abs: 
1235979,Mazoyer et al. 1988,Survival of rabbit platelets labeled with gallium 67,"The viability of rabbit platelets labeled with radioactive gallium was determined to analyze the feasibility of using platelets labeled with gallium 68 as an imaging reagent for positron emission tomography. Platelets were labeled with a complex of the longer lived gallium 67 and mercaptopyridine-N-oxide (MPO) or with sodium chromate Cr 51. Their survival after transfusion was measured. Labelling efficiency of 67Ga-MPO was 6.5% to 45.8% (26.8% +/- 2.8%) when platelets were suspended in saline solution, but was much lower (1.6% +/- 0.8%) in plasma. Platelets labeled with either radioisotope in a saline medium survived as well as platelets labeled with 51Cr in plasma. Recovery values 1 hour after transfusion and mean platelet survivals were 68.6% +/- 4.9% and 3.4 +/- 0.2 days for 67Ga in saline solution, 76.5% +/- 6.8% and 3.8 +/- 0.5 days for 51Cr in saline solution, and 73.7% +/- 7.4% and 3.6 +/- 0.5 days for 51Cr in plasma. Labeled platelet concentrates always contained extra radioactivity not firmly bound to viable platelets. A postlabeling wash in saline solution did not reduce this contamination and resulted in reduction of the number of viable platelets. The results showed that rabbit platelets labeled with 67Ga-MPO survived in the circulation as well as those labeled by a standard protocol with sodium chromate Cr 51.","Survival of rabbit platelets labeled with gallium 67 Abs: The viability of rabbit platelets labeled with radioactive gallium was determined to analyze the feasibility of using platelets labeled with gallium 68 as an imaging reagent for positron emission tomography. Platelets were labeled with a complex of the longer lived gallium 67 and mercaptopyridine-N-oxide (MPO) or with sodium chromate Cr 51. Their survival after transfusion was measured. Labelling efficiency of 67Ga-MPO was 6.5% to 45.8% (26.8% +/- 2.8%) when platelets were suspended in saline solution, but was much lower (1.6% +/- 0.8%) in plasma. Platelets labeled with either radioisotope in a saline medium survived as well as platelets labeled with 51Cr in plasma. Recovery values 1 hour after transfusion and mean platelet survivals were 68.6% +/- 4.9% and 3.4 +/- 0.2 days for 67Ga in saline solution, 76.5% +/- 6.8% and 3.8 +/- 0.5 days for 51Cr in saline solution, and 73.7% +/- 7.4% and 3.6 +/- 0.5 days for 51Cr in plasma. Labeled platelet concentrates always contained extra radioactivity not firmly bound to viable platelets. A postlabeling wash in saline solution did not reduce this contamination and resulted in reduction of the number of viable platelets. The results showed that rabbit platelets labeled with 67Ga-MPO survived in the circulation as well as those labeled by a standard protocol with sodium chromate Cr 51."
1235976,van der Meer et al. 1988,"Toxicity of sodium chromate and 3,4-dichloroaniline to crustaceans",BIOSIS COPYRIGHT: BIOL ABS. RRM WATER POLLUTION PALAEMONETES-VARIANS PALAEMON-ELEGANS NEOMYSIS-INTEGER PRAUNUS-FLEXUOSUS DAPHNIA-MAGNA ARTEMIA-SP,"Toxicity of sodium chromate and 3,4-dichloroaniline to crustaceans Abs: BIOSIS COPYRIGHT: BIOL ABS. RRM WATER POLLUTION PALAEMONETES-VARIANS PALAEMON-ELEGANS NEOMYSIS-INTEGER PRAUNUS-FLEXUOSUS DAPHNIA-MAGNA ARTEMIA-SP"
1235971,Sugiyama et al. 1988,Stimulation of polyadenosine diphosphoribose synthesis by DNA lesions induced by sodium chromate in Chinese hamster V-79 cells,"Polyadenosine diphosphoribose [poly(ADP-ribose)] synthesis was stimulated by DNA lesions induced with Na2CrO4 and methyl methanesulfonate (MMS) in Chinese hamster V-79 cells. Na2CrO4 and MMS induced DNA single-strand breaks in a concentration-dependent manner; however, the breaks induced by Na2CrO4 were &quot;protein associated&quot; while those induced by MMS were not. MMS stimulated in a dose-dependent fashion the synthesis of poly(ADP-ribose) up to 6-fold above the control. Na2CrO4 also induced poly(ADP-ribose) synthesis, but the level of synthesis was less than 3-fold. Control experiments demonstrated that Na2CrO4 treatment of cells did not affect their ability to synthesize poly(ADP-ribose) in response to DNA damage. Treatment of cells with Na2CrO4 and MMS induced more poly(ADP-ribose) synthesis than each agent alone; however, whenever Na2CrO4 was utilized, the breaks required proteinase K to be detected. Following removal of extracellular chromate, the DNA strand breaks induced by 0.2 mM Na2CrO4 were repaired quickly during the first hour but more slowly for the next 3 h. In the presence of 3-aminobenzamide, an inhibitor of poly(ADP-ribose) synthesis, the repair of DNA breaks was reduced. These results suggest that DNA protein-associated breaks produced by Na2CrO4 were recognized by poly(ADP-ribose) polymerase and that there are differences in poly(ADP-ribose) synthesis in response to Na2CrO4 and MMS. The results also suggest that the repair of breaks induced by Na2CrO4 are associated with poly(ADP-ribose) synthesis, but perhaps because most of these breaks are protein associated, there is less stimulation of poly(ADP-ribose) synthesis.","Stimulation of polyadenosine diphosphoribose synthesis by DNA lesions induced by sodium chromate in Chinese hamster V-79 cells Abs: Polyadenosine diphosphoribose [poly(ADP-ribose)] synthesis was stimulated by DNA lesions induced with Na2CrO4 and methyl methanesulfonate (MMS) in Chinese hamster V-79 cells. Na2CrO4 and MMS induced DNA single-strand breaks in a concentration-dependent manner; however, the breaks induced by Na2CrO4 were &quot;protein associated&quot; while those induced by MMS were not. MMS stimulated in a dose-dependent fashion the synthesis of poly(ADP-ribose) up to 6-fold above the control. Na2CrO4 also induced poly(ADP-ribose) synthesis, but the level of synthesis was less than 3-fold. Control experiments demonstrated that Na2CrO4 treatment of cells did not affect their ability to synthesize poly(ADP-ribose) in response to DNA damage. Treatment of cells with Na2CrO4 and MMS induced more poly(ADP-ribose) synthesis than each agent alone; however, whenever Na2CrO4 was utilized, the breaks required proteinase K to be detected. Following removal of extracellular chromate, the DNA strand breaks induced by 0.2 mM Na2CrO4 were repaired quickly during the first hour but more slowly for the next 3 h. In the presence of 3-aminobenzamide, an inhibitor of poly(ADP-ribose) synthesis, the repair of DNA breaks was reduced. These results suggest that DNA protein-associated breaks produced by Na2CrO4 were recognized by poly(ADP-ribose) polymerase and that there are differences in poly(ADP-ribose) synthesis in response to Na2CrO4 and MMS. The results also suggest that the repair of breaks induced by Na2CrO4 are associated with poly(ADP-ribose) synthesis, but perhaps because most of these breaks are protein associated, there is less stimulation of poly(ADP-ribose) synthesis."
1235964,Esnard et al. 1988,Purification of the cystatin C-like inhibitors from urine of nephropathic rats,Two cysteine proteinase inhibitors of the cystatin C type have been purified from urine of sodium chromate-treated rats. Both strongly inhibit papain as well as rat liver cathepsin L (Ki less than 10(-11) M) whereas rat liver cathepsins B and H are inhibited to a lesser extent. They differ by their apparent molecular mass of 17 kDa and 22 kDa and by their isoelectric point greater than or equal to 9.5 and 7.7 respectively. These two molecules share complete immunochemical identity and are precipitated by antibodies directed against human cystatin C but not by anti rat thiostatin and anti rat H-kininogen antibodies. They are also found in large amounts in seminal vesicles where they represent most of the cysteine proteinase inhibitory capacity.,Purification of the cystatin C-like inhibitors from urine of nephropathic rats Abs: Two cysteine proteinase inhibitors of the cystatin C type have been purified from urine of sodium chromate-treated rats. Both strongly inhibit papain as well as rat liver cathepsin L (Ki less than 10(-11) M) whereas rat liver cathepsins B and H are inhibited to a lesser extent. They differ by their apparent molecular mass of 17 kDa and 22 kDa and by their isoelectric point greater than or equal to 9.5 and 7.7 respectively. These two molecules share complete immunochemical identity and are precipitated by antibodies directed against human cystatin C but not by anti rat thiostatin and anti rat H-kininogen antibodies. They are also found in large amounts in seminal vesicles where they represent most of the cysteine proteinase inhibitory capacity.
1235959,Goh 1988,Epidemiology of contact allergy in Singapore,"The prevalence of contact allergy in 2471 patients patch tested in Singapore was 49.2% (571/1160) in women and 49.8% (653/1311) in men (sex difference not significant). The rate appeared to increase with age (43.7% in those less than 20 years, 50.6% between 20 and 49 years, and 63.1% in those greater than 49 years). There was no significant difference in the prevalence of contact allergy among the major races (Chinese, Malay, and Indian) of Singapore. Contact allergies in 16.8% (96/571) of women and 38.9% (254/653) of men (p less than 0.001) were occupational. Nickel, fragrance mix, proflavine, and chromate were common sensitizers. The male:female prevalence of nickel allergy was 1:2 (sex difference p less than 0.001) and for chromate was 7:1 (sex difference p less than 0.001). Chromate sensitivity was occupational in 87.7% (121/138) of men and 47.1% (8/17) of women (sex difference p less than 0.001). Proflavine, neomycin, and clioquinol were the more common medicament sensitizers.","Epidemiology of contact allergy in Singapore Abs: The prevalence of contact allergy in 2471 patients patch tested in Singapore was 49.2% (571/1160) in women and 49.8% (653/1311) in men (sex difference not significant). The rate appeared to increase with age (43.7% in those less than 20 years, 50.6% between 20 and 49 years, and 63.1% in those greater than 49 years). There was no significant difference in the prevalence of contact allergy among the major races (Chinese, Malay, and Indian) of Singapore. Contact allergies in 16.8% (96/571) of women and 38.9% (254/653) of men (p less than 0.001) were occupational. Nickel, fragrance mix, proflavine, and chromate were common sensitizers. The male:female prevalence of nickel allergy was 1:2 (sex difference p less than 0.001) and for chromate was 7:1 (sex difference p less than 0.001). Chromate sensitivity was occupational in 87.7% (121/138) of men and 47.1% (8/17) of women (sex difference p less than 0.001). Proflavine, neomycin, and clioquinol were the more common medicament sensitizers."
1235958,Carr 1957,The determination of blood volume and red cell survival time with special emphasis on the use of sodium chromate,,The determination of blood volume and red cell survival time with special emphasis on the use of sodium chromate Abs: 
1235957,Read and  Gilbertsen 1957,Radioactive sodium chromate and the measurement of red cell and plasma volume in man,,Radioactive sodium chromate and the measurement of red cell and plasma volume in man Abs: 
1235952,Buttner et al. 1988,"Chromate effects on human erythrocytes--investigations on sulphydryl groups, cross-linking of membrane proteins and electromechanical properties in the coulter-counter","The carcinogen chromate inactivates its own carrier in the human erythrocyte membrane. This effect is paralleled by the inhibition of chromate uptake by the sulphydryl reagents N-ethylmaleimide and iodoacetate. However, no decrease in the sulphydryl content of erythrocyte membranes treated with up to 100 mM chromate was detected. By SDS gel electrophoresis, a limited cross-linking of red cell membrane proteins was found at 100 mM chromate, but not at cytotoxic concentrations up to 10 mM chromate. Erythrocytes treated with up to 100 mM chromate exhibited no change in the ""dielectric breakdown"", i.e. the sharp decrease of the apparent cellular volume at a critical detector current.","Chromate effects on human erythrocytes--investigations on sulphydryl groups, cross-linking of membrane proteins and electromechanical properties in the coulter-counter Abs: The carcinogen chromate inactivates its own carrier in the human erythrocyte membrane. This effect is paralleled by the inhibition of chromate uptake by the sulphydryl reagents N-ethylmaleimide and iodoacetate. However, no decrease in the sulphydryl content of erythrocyte membranes treated with up to 100 mM chromate was detected. By SDS gel electrophoresis, a limited cross-linking of red cell membrane proteins was found at 100 mM chromate, but not at cytotoxic concentrations up to 10 mM chromate. Erythrocytes treated with up to 100 mM chromate exhibited no change in the ""dielectric breakdown"", i.e. the sharp decrease of the apparent cellular volume at a critical detector current."
1235949,Ottenwaelder et al. 1988,Uptake of 51Cr(VI) by human erythrocytes: Evidence for a carrier-mediated transport mechanism,"Uptake of 20 micron 51Cr(VI) by resuspended red blood cells (RBC) (0.9% saline) was studied. Inhibition of the specific anion carrier system ""band-3-protein"" of RBC membrane with ""SITS"" (4-acetamido-4'-cyanatostilbene-2,2'-disulphonic acid) resulted in a non-competitive type of inhibition for chromium uptake. It is concluded that Cr(VI) is transported by participation with this system. Intracellularly, chromium is almost quantitatively bound to hemoglobin and trapped for the cell's lifetime. Glutathione (GSH) is possibly involved in this process as indicated by incubation experiments of RBC with 10 mM Na2(51)CrO4. In these experiments, a rapid decrease of GSH content of the cells was observed.","Uptake of 51Cr(VI) by human erythrocytes: Evidence for a carrier-mediated transport mechanism Abs: Uptake of 20 micron 51Cr(VI) by resuspended red blood cells (RBC) (0.9% saline) was studied. Inhibition of the specific anion carrier system ""band-3-protein"" of RBC membrane with ""SITS"" (4-acetamido-4'-cyanatostilbene-2,2'-disulphonic acid) resulted in a non-competitive type of inhibition for chromium uptake. It is concluded that Cr(VI) is transported by participation with this system. Intracellularly, chromium is almost quantitatively bound to hemoglobin and trapped for the cell's lifetime. Glutathione (GSH) is possibly involved in this process as indicated by incubation experiments of RBC with 10 mM Na2(51)CrO4. In these experiments, a rapid decrease of GSH content of the cells was observed."
1235947,Debetto et al. 1988,Uptake of chromate by rat thymocytes and role of glutathione in its cytoplasmic reduction,"1. Chromate is taken up by rat thymocytes over a wide range of extracellular chromate concentrations (0.074 +/- 5.0 mM). 2. Chromate uptake followed Michaelis-Menten kinetics and was inhibited by 4-acetamido-4'-isothiocyano-stilbene-2,2'-disulphonic acid, suggesting that the anion carrier was responsible for the uptake by rat thymocytes. 3. The decrease in chromate uptake by the thiol(SH)-blocking agent diethyl maleate, the increased chromate uptake caused by the thiol-protecting agent dithiothreitol, and the reduction of glutathione/glutathione disulphide ratio indicated that the maintenance of the integrity of SH-groups greatly influenced the uptake and reduction of Cr(VI), and that glutathione may be responsible for the intracellular reduction of Cr(VI) to Cr(III).","Uptake of chromate by rat thymocytes and role of glutathione in its cytoplasmic reduction Abs: 1. Chromate is taken up by rat thymocytes over a wide range of extracellular chromate concentrations (0.074 +/- 5.0 mM). 2. Chromate uptake followed Michaelis-Menten kinetics and was inhibited by 4-acetamido-4'-isothiocyano-stilbene-2,2'-disulphonic acid, suggesting that the anion carrier was responsible for the uptake by rat thymocytes. 3. The decrease in chromate uptake by the thiol(SH)-blocking agent diethyl maleate, the increased chromate uptake caused by the thiol-protecting agent dithiothreitol, and the reduction of glutathione/glutathione disulphide ratio indicated that the maintenance of the integrity of SH-groups greatly influenced the uptake and reduction of Cr(VI), and that glutathione may be responsible for the intracellular reduction of Cr(VI) to Cr(III)."
1235946,Samitz 1956,Studies of chromate dermatitis,,Studies of chromate dermatitis Abs: 
1235944,Lück and  Jentsch 1988,Chromium dermatitis caused by epoxy resin,"A case report was presented for a 26 year old male with severe itching, fissuring, and swelling of the hands. The patient was employed as a tiler in a factory manufacturing prefabricated concrete panels; cement at a factory was rendered low in chromate by adding ferrous-sulfate. The patient had intensive skin contact with a two part epoxy resin adhesive used for tiling work. Patch testing showed a 3+ positive reaction to potassium-dichromate (7778509). Examination of the two components of the epoxy resin adhesive indicated the presence of chromate; the manufacturer indicated that Portland cement was used as a filler material. Since it is essential to track down the exposure to hexavalent chromium compounds, a test was developed to qualitatively detect the presence of chromates in test substances. The detection limit was 0.5 to 1 parts per million (ppm) for fresh cement and 3 to 5ppm in other materials. The method uses a solution consisting of 970 milliliters ethanol and 30 milliliters 8N hydrochloric-acid saturated with diphenylcarbazide. A filter paper strip is used to pick up the liquid, after which the reactant was applied. Chromate was indicated by a red/violet color change.","Chromium dermatitis caused by epoxy resin Abs: A case report was presented for a 26 year old male with severe itching, fissuring, and swelling of the hands. The patient was employed as a tiler in a factory manufacturing prefabricated concrete panels; cement at a factory was rendered low in chromate by adding ferrous-sulfate. The patient had intensive skin contact with a two part epoxy resin adhesive used for tiling work. Patch testing showed a 3+ positive reaction to potassium-dichromate (7778509). Examination of the two components of the epoxy resin adhesive indicated the presence of chromate; the manufacturer indicated that Portland cement was used as a filler material. Since it is essential to track down the exposure to hexavalent chromium compounds, a test was developed to qualitatively detect the presence of chromates in test substances. The detection limit was 0.5 to 1 parts per million (ppm) for fresh cement and 3 to 5ppm in other materials. The method uses a solution consisting of 970 milliliters ethanol and 30 milliliters 8N hydrochloric-acid saturated with diphenylcarbazide. A filter paper strip is used to pick up the liquid, after which the reactant was applied. Chromate was indicated by a red/violet color change."
1235939,Shi and  Dalal 1988,On the mechanism of the chromate reduction by glutathione: ESR evidence for the glutathionyl radical and an isolable Cr(V) intermediate,"With a view of elucidating the role of glutathione (GSH) in the biochemical pathways of the chromate-exposure related carcinogenesis, we carried out electron spin resonance (ESR) spectroscopic investigations of the chromate-GSH redox reactions. The ESR measurements, employing spin-traps, provide evidence for the involvement of the glutathione (GS) radical, as well as an isolable Cr(V)-glutathione intermediate. These results indicate a new mechanism for the reduction of chromate by GSH in in vitro cellular environment and help understand the (unexpected) increase in Cr(VI)-induced DNA strand breaks at elevated GSH levels.","On the mechanism of the chromate reduction by glutathione: ESR evidence for the glutathionyl radical and an isolable Cr(V) intermediate Abs: With a view of elucidating the role of glutathione (GSH) in the biochemical pathways of the chromate-exposure related carcinogenesis, we carried out electron spin resonance (ESR) spectroscopic investigations of the chromate-GSH redox reactions. The ESR measurements, employing spin-traps, provide evidence for the involvement of the glutathione (GS) radical, as well as an isolable Cr(V)-glutathione intermediate. These results indicate a new mechanism for the reduction of chromate by GSH in in vitro cellular environment and help understand the (unexpected) increase in Cr(VI)-induced DNA strand breaks at elevated GSH levels."
1235937,Avnstorp 1989,Prevalence of cement eczema in Denmark before and since addition of ferrous sulfate to Danish cement,"This is a study of the prevalences of chromate allergy and hand eczema among workers engaged in the manufacture of pre-fabricated concrete building components in Denmark in 1981 and again in 1987. In September 1981 the chromate content of cement manufactured and sold in Denmark was reduced to not more than 2 ppm (parts per million) of water-soluble chromate. This was accomplished by adding ferrous sulfate, thus increasing the cost of the cement by about 1%. There was a statistically significant decrease in the prevalence of chromate allergy and hand eczema following the addition of ferrous sulfate, but there was no change in the frequency of skin irritation. The economic benefit of adding ferrous sulfate was demonstrated by a decrease in the need for dermatological services and topical steroid treatment. Cement eczema as a result of chromate allergy is a common occupational dermatitis among workers in the building and construction industries and a reduction in the chromate content of cement would appear to be a reasonable preventive measure in areas where there is a large concentration of construction industries.","Prevalence of cement eczema in Denmark before and since addition of ferrous sulfate to Danish cement Abs: This is a study of the prevalences of chromate allergy and hand eczema among workers engaged in the manufacture of pre-fabricated concrete building components in Denmark in 1981 and again in 1987. In September 1981 the chromate content of cement manufactured and sold in Denmark was reduced to not more than 2 ppm (parts per million) of water-soluble chromate. This was accomplished by adding ferrous sulfate, thus increasing the cost of the cement by about 1%. There was a statistically significant decrease in the prevalence of chromate allergy and hand eczema following the addition of ferrous sulfate, but there was no change in the frequency of skin irritation. The economic benefit of adding ferrous sulfate was demonstrated by a decrease in the need for dermatological services and topical steroid treatment. Cement eczema as a result of chromate allergy is a common occupational dermatitis among workers in the building and construction industries and a reduction in the chromate content of cement would appear to be a reasonable preventive measure in areas where there is a large concentration of construction industries."
1235936,Tavera et al. 1989,"A rapid two-step purification of rat cystatin C, one major inhibitor of cysteine proteinases","Rat cystatin C was purified to apparent homogeneity from rat urine after induction of a tubular dysfunction with sodium chromate. Twentyfold concentrated urine was chromatographed by a rapid purification procedure. A two-step purification including affinity chromatography on carboxymethyl papain- Sepharose and high-resolution anion exchange chromatography was developed. The purified protein has an apparent molecular mass of 15 kDa and pI of 10.2; its aminoacid composition was similar to human cystatin C. As opposed to previous data, purified urinary rat cystatin C did not contain significant amounts of carbohydrate. Antisera against rat cystatin C, raised in rabbits, partially cross-reacted with human and mouse cystatin C, indicating their antigenic similarities. Like human cystatin C, native rat cystatin C, named slow form, is degraded into a more acidic form, called fast form, by a loss of N-terminal amino acids; fast form displayed a pI of 9.4.","A rapid two-step purification of rat cystatin C, one major inhibitor of cysteine proteinases Abs: Rat cystatin C was purified to apparent homogeneity from rat urine after induction of a tubular dysfunction with sodium chromate. Twentyfold concentrated urine was chromatographed by a rapid purification procedure. A two-step purification including affinity chromatography on carboxymethyl papain- Sepharose and high-resolution anion exchange chromatography was developed. The purified protein has an apparent molecular mass of 15 kDa and pI of 10.2; its aminoacid composition was similar to human cystatin C. As opposed to previous data, purified urinary rat cystatin C did not contain significant amounts of carbohydrate. Antisera against rat cystatin C, raised in rabbits, partially cross-reacted with human and mouse cystatin C, indicating their antigenic similarities. Like human cystatin C, native rat cystatin C, named slow form, is degraded into a more acidic form, called fast form, by a loss of N-terminal amino acids; fast form displayed a pI of 9.4."
1235932,Candide et al. 1989,Photosensitization of Wi26-VA4 transformed human fibroblasts by low density lipoprotein loaded with the anticancer porphyrin mixture photofrin II: evidence for endoplasmic reticulum alteration,"Wi26 VA4 cells (SV40-transformed human lung fibroblasts) were incubated with low density lipoprotein (LDL) loaded with the anticancer porphyrin mixture photofrin II (P2). After labelling with 51Cr sodium chromate, cells were exposed to near UV light. After light exposure, kinetics of 51Cr release by cells were studied as a probe of cell damage. The activity of acyl-coenzyme A:cholesterol-O-acyltransferase, a key enzyme of cholesterol metabolism localized in endoplasmic reticulum (ER), was decreased as a function of the irradiation time in cells pre-incubated with P2-LDL. This result suggests that ER alteration occurred during cell photosensitization by P2-LDL.","Photosensitization of Wi26-VA4 transformed human fibroblasts by low density lipoprotein loaded with the anticancer porphyrin mixture photofrin II: evidence for endoplasmic reticulum alteration Abs: Wi26 VA4 cells (SV40-transformed human lung fibroblasts) were incubated with low density lipoprotein (LDL) loaded with the anticancer porphyrin mixture photofrin II (P2). After labelling with 51Cr sodium chromate, cells were exposed to near UV light. After light exposure, kinetics of 51Cr release by cells were studied as a probe of cell damage. The activity of acyl-coenzyme A:cholesterol-O-acyltransferase, a key enzyme of cholesterol metabolism localized in endoplasmic reticulum (ER), was decreased as a function of the irradiation time in cells pre-incubated with P2-LDL. This result suggests that ER alteration occurred during cell photosensitization by P2-LDL."
1235929,Gartland et al. 1989,Investigations into the biochemical effects of region-specific nephrotoxins,"1H NMR spectroscopy provides a useful initial biochemical screen with which to detect abnormal patterns of metabolites in urine collected from animals with different sites of nephrotoxic lesions. Male Fischer 344 rats were treated with nephrotoxic doses of sodium chromate (pars convoluta of proximal tubule), cisplatin, hexachlorobutadiene, mercury II chloride (pars recta of proximal tubule), propylene imine, and bromoethanamine (renal papilla) in order to induce damage in specific regions of the kidney. Urine was collected for up to 48 hr after dosing and was analyzed by 1H NMR spectroscopy (400 MHz) and conventional biochemical methods to provide biochemical fingerprints of urine in various site-specific nephrotoxic states. Hexachlorobutadiene and HgCl2 produced severe glycosuria and transient enzymuria. 1H NMR urinalysis revealed aminoaciduria, glycosuria, and lactic aciduria after exposure to all proximal tubular toxins except cisplatin, whereas papillary insult resulted in early elevations in urinary trimethylamine N-oxide and dimethylamine, together with later elevations in urinary acetate, succinate, and N,N-dimethylglycine (after propylene imine). Trimethylamine N-oxide and dimethylamine are suggested as novel markers of site-specific renal papillary injury in the rat.","Investigations into the biochemical effects of region-specific nephrotoxins Abs: 1H NMR spectroscopy provides a useful initial biochemical screen with which to detect abnormal patterns of metabolites in urine collected from animals with different sites of nephrotoxic lesions. Male Fischer 344 rats were treated with nephrotoxic doses of sodium chromate (pars convoluta of proximal tubule), cisplatin, hexachlorobutadiene, mercury II chloride (pars recta of proximal tubule), propylene imine, and bromoethanamine (renal papilla) in order to induce damage in specific regions of the kidney. Urine was collected for up to 48 hr after dosing and was analyzed by 1H NMR spectroscopy (400 MHz) and conventional biochemical methods to provide biochemical fingerprints of urine in various site-specific nephrotoxic states. Hexachlorobutadiene and HgCl2 produced severe glycosuria and transient enzymuria. 1H NMR urinalysis revealed aminoaciduria, glycosuria, and lactic aciduria after exposure to all proximal tubular toxins except cisplatin, whereas papillary insult resulted in early elevations in urinary trimethylamine N-oxide and dimethylamine, together with later elevations in urinary acetate, succinate, and N,N-dimethylglycine (after propylene imine). Trimethylamine N-oxide and dimethylamine are suggested as novel markers of site-specific renal papillary injury in the rat."
1235928,Plunkett et al. 1989,Implantation of dispersed cells into primate brain,"Although several experimental therapies such as dopaminergic cell implantation in parkinsonian models and intratumoral placement of lymphokine-activated killer cells require intracerebral deposition of dispersed cell suspensions, a successful technique of needle implantation of cells into primate brain has not been demonstrated. The authors have sought to establish a stereotaxic technique to predictably deposit dispersed cells in primate brain. Human lymphocytes were cultured in recombinant interleukin-2, labeled with sodium 51 chromate (51Cr), and stereotaxically injected into the frontal white matter of six anesthetized rhesus monkeys. A 10-microliters aliquot of cell suspension (2 X 10(7) cells/ml) was deposited 16 mm deep to the dura at 5 microliters/min via Hamilton No. 22s or 26s needles. Five control aliquots were counted for each injection. Reflux out of the needle track was absorbed on gauze, and the recovered cells were counted. The animals were sacrificed 1 hour after implantation and the brain was removed and sectioned such that the cortex and white matter along the needle track were separate. The tissue sections were then counted. Recovery was expressed as the percentage of total injected radioactivity (cpm) that was present in each brain section. Two additional injected hemispheres were processed for autoradiography and histological study. Cell recovery in the brain (mean +/- standard deviation) was 87.2% +/- 13.9% (3.3% +/- 4.9% in cortex and 83.9% +/- 15.9% in white matter). The autoradiograms and histological examination showed a dense accumulation of radioactivity (cells) at the target site and minimal radioactivity (cells) in the needle track. Accurate intracerebral deposition of dispersed cells in primates was achieved with the technique described. This knowledge permits reliable stereotaxic implantation of cells into the brains of nonhuman primates and humans for investigation and therapy.","Implantation of dispersed cells into primate brain Abs: Although several experimental therapies such as dopaminergic cell implantation in parkinsonian models and intratumoral placement of lymphokine-activated killer cells require intracerebral deposition of dispersed cell suspensions, a successful technique of needle implantation of cells into primate brain has not been demonstrated. The authors have sought to establish a stereotaxic technique to predictably deposit dispersed cells in primate brain. Human lymphocytes were cultured in recombinant interleukin-2, labeled with sodium 51 chromate (51Cr), and stereotaxically injected into the frontal white matter of six anesthetized rhesus monkeys. A 10-microliters aliquot of cell suspension (2 X 10(7) cells/ml) was deposited 16 mm deep to the dura at 5 microliters/min via Hamilton No. 22s or 26s needles. Five control aliquots were counted for each injection. Reflux out of the needle track was absorbed on gauze, and the recovered cells were counted. The animals were sacrificed 1 hour after implantation and the brain was removed and sectioned such that the cortex and white matter along the needle track were separate. The tissue sections were then counted. Recovery was expressed as the percentage of total injected radioactivity (cpm) that was present in each brain section. Two additional injected hemispheres were processed for autoradiography and histological study. Cell recovery in the brain (mean +/- standard deviation) was 87.2% +/- 13.9% (3.3% +/- 4.9% in cortex and 83.9% +/- 15.9% in white matter). The autoradiograms and histological examination showed a dense accumulation of radioactivity (cells) at the target site and minimal radioactivity (cells) in the needle track. Accurate intracerebral deposition of dispersed cells in primates was achieved with the technique described. This knowledge permits reliable stereotaxic implantation of cells into the brains of nonhuman primates and humans for investigation and therapy."
1235926,Sugiyama et al. 1989,Vitamin B2-enhancement of sodium chromate (VI)--Induced DNA single strand breaks: ESR study of the action of vitamin B2,"Incubation of Chinese hamster V-79 cells with Na2CrO4 plus vitamin B2 resulted in an increase of Na2CrO4-induced DNA single strand breaks. Electron spin resonance (ESR) studies showed that vitamin B2 enhanced the formation of both hydroxyl radical and tetraperoxochromate (V) during the reaction of Na2CrO4 with hydrogen peroxide. Furthermore, ESR studies demonstrated that a chromium (V) species with a g value of 1.977 was formed by the reaction of Na2CrO4 with vitamin B2. These results indicate that chromate reacts with vitamin B2 to form chromium (V) species and also suggest that the enhancement effect of vitamin B2 on chromate-induced DNA single strand breaks may result from an increase of chromium (V)-related hydroxyl radical formation.","Vitamin B2-enhancement of sodium chromate (VI)--Induced DNA single strand breaks: ESR study of the action of vitamin B2 Abs: Incubation of Chinese hamster V-79 cells with Na2CrO4 plus vitamin B2 resulted in an increase of Na2CrO4-induced DNA single strand breaks. Electron spin resonance (ESR) studies showed that vitamin B2 enhanced the formation of both hydroxyl radical and tetraperoxochromate (V) during the reaction of Na2CrO4 with hydrogen peroxide. Furthermore, ESR studies demonstrated that a chromium (V) species with a g value of 1.977 was formed by the reaction of Na2CrO4 with vitamin B2. These results indicate that chromate reacts with vitamin B2 to form chromium (V) species and also suggest that the enhancement effect of vitamin B2 on chromate-induced DNA single strand breaks may result from an increase of chromium (V)-related hydroxyl radical formation."
1235925,Sugiyama et al. 1989,"Effect of vitamin E on survival, glutathione reductase and formation of chromium (V) in Chinese hamster V-79 cells treated with sodium chromate (VI)","The effect of vitamin E on cytotoxicity induced by Na2CrO4 was evaluated by colony-forming assay using Chinese hamster V-79 cells. Pre-treatment with alpha-tocopherol succinate (vitamin E) for 24 h prior to exposure to Na2CrO4 resulted in a marked decrease in the cytotoxicity caused by this compound. The reduction of chromate-induced cytotoxicity was observed at all concentrations of Na2CrO4 (5-15 microM), and the protective effect increased with higher concentrations of vitamin E (5-25 microM). The level of glutathione reductase activity, which is capable of reducing chromate, was not affected by cellular pre-treatment with vitamin E. However, Na2CrO4 decreased glutathione reductase activity in a concentration-dependent fashion (5-15 microM) and pretreatment with vitamin E resulted in a significant recovery of enzyme activity suppressed by Na2CrO4, suggesting that this enzyme inhibition is linked to the cytotoxicity of this metal. Electron spin resonance studies showed that a paramagnetic chromium (V) complex was formed in cells treated with Na2CrO4, and that cellular pre-treatment with vitamin E reduced the formation of this chromium (V) intermediate. These results indicate that vitamin E protects cells from chromate-induced cytotoxicity as well as from enzyme inhibition, and also suggest that Na2CrO4-induced cytotoxicity is mediated by the generation of a reactive intermediate.","Effect of vitamin E on survival, glutathione reductase and formation of chromium (V) in Chinese hamster V-79 cells treated with sodium chromate (VI) Abs: The effect of vitamin E on cytotoxicity induced by Na2CrO4 was evaluated by colony-forming assay using Chinese hamster V-79 cells. Pre-treatment with alpha-tocopherol succinate (vitamin E) for 24 h prior to exposure to Na2CrO4 resulted in a marked decrease in the cytotoxicity caused by this compound. The reduction of chromate-induced cytotoxicity was observed at all concentrations of Na2CrO4 (5-15 microM), and the protective effect increased with higher concentrations of vitamin E (5-25 microM). The level of glutathione reductase activity, which is capable of reducing chromate, was not affected by cellular pre-treatment with vitamin E. However, Na2CrO4 decreased glutathione reductase activity in a concentration-dependent fashion (5-15 microM) and pretreatment with vitamin E resulted in a significant recovery of enzyme activity suppressed by Na2CrO4, suggesting that this enzyme inhibition is linked to the cytotoxicity of this metal. Electron spin resonance studies showed that a paramagnetic chromium (V) complex was formed in cells treated with Na2CrO4, and that cellular pre-treatment with vitamin E reduced the formation of this chromium (V) intermediate. These results indicate that vitamin E protects cells from chromate-induced cytotoxicity as well as from enzyme inhibition, and also suggest that Na2CrO4-induced cytotoxicity is mediated by the generation of a reactive intermediate."
1235924,Ducatman 1989,"Dimethylformamide, metal dyes, and testicular cancer","The possibility that dimethylformamide (68122) (DMF) may act as a cocarcinogen in the development of testicular cancer was suggested. Several studies were cited in which workers have suffered testicular cancer following exposure to DMF, including workers in a small tannery and aircraft mechanics at two separate repair facilities. A study conducted by a DMF manufacturer indicated a significant excess of several cancers, but no excess for testicular cancer. This result may have occurred because DMF is not itself a cause of testicular cancer, because there was little skin contact with DMF, or because exposure was in some way different from the other uncontrolled exposures. The author suggests that other exposures common to leather tanners and aircraft repairmen be examined. The tanners who were affected handled significant amounts of chromium (7440473) and used both chromate and cadmium (7440439) based dyes. Airframe repairmen were exposed to zinc-chromate (13530659) primer paints and cadmium (7440439) alloys. A study of U.S. Navy personnel indicated significant excesses of testicular cancer in aviation support equipment technicians and all active duty mechanics. These groups of workers were exposed to both chromate based paints and solvents. Swiss painters who used metal protective primers containing zinc-chromate suffered excess testicular cancer as well. The possibility that DMF, acting as a bipolar solvent, increases skin absorption and tissue availability of metal carcinogens such as chromates should be considered.","Dimethylformamide, metal dyes, and testicular cancer Abs: The possibility that dimethylformamide (68122) (DMF) may act as a cocarcinogen in the development of testicular cancer was suggested. Several studies were cited in which workers have suffered testicular cancer following exposure to DMF, including workers in a small tannery and aircraft mechanics at two separate repair facilities. A study conducted by a DMF manufacturer indicated a significant excess of several cancers, but no excess for testicular cancer. This result may have occurred because DMF is not itself a cause of testicular cancer, because there was little skin contact with DMF, or because exposure was in some way different from the other uncontrolled exposures. The author suggests that other exposures common to leather tanners and aircraft repairmen be examined. The tanners who were affected handled significant amounts of chromium (7440473) and used both chromate and cadmium (7440439) based dyes. Airframe repairmen were exposed to zinc-chromate (13530659) primer paints and cadmium (7440439) alloys. A study of U.S. Navy personnel indicated significant excesses of testicular cancer in aviation support equipment technicians and all active duty mechanics. These groups of workers were exposed to both chromate based paints and solvents. Swiss painters who used metal protective primers containing zinc-chromate suffered excess testicular cancer as well. The possibility that DMF, acting as a bipolar solvent, increases skin absorption and tissue availability of metal carcinogens such as chromates should be considered."
1235922,Rossi and  Wetterhahn 1989,Chromium(V) is produced upon reduction of chromate by mitochondrial electron transport chain complexes,"Incubation of chromate with isolated rat liver submitochondrial particles under anaerobic conditions in vitro results in reduction of chromium(VI) and formation of chromium(V). In the presence of NADH, submitochondrial particles (SMPs) were active in reducing chromate as shown by UV-vis spectroscopic studies, and forming a chromium(V) species which was detectable by electron paramagnetic resonance spectroscopy. In the presence of succinate, SMPs were less effective in reducing chromate and forming chromium(V) relative to their NADH-dependent activity. However, SMPs showed a higher rate of oxygen depletion with NADH as compared to succinate as substrate, suggesting that differences in the NADH-dependent versus succinate-dependent chromate-reductase activity of SMPs is probably due to differences in efficiency of electron donation by succinate and NADH. The use of specific electron transport chain inhibitors allowed the sites of chromium(VI) reduction and chromium(V) formation in SMPs to be determined. Rotenone, antimycin and cyanide all produced approximately 40% inhibition of the NADH-dependent chromate-reductase activity. Thus, complex I (NADH:ubiquinone oxidoreductase) appears to be responsible for the inhibitor-insensitive, and complex IV (ferrocytochrome c:oxygen oxidoreductase) for the inhibitor-sensitive NADH-dependent chromium(VI) reduction and chromium(V) formation. Cyanide and antimycin produced approximately 50% inhibition of the succinate-dependent chromate-reductase activity of SMPs, while no detectable inhibition was observed with rotenone. These results confirm the chromate-reductase activity of complex IV, and suggest that complex II (succinate:ubiquinone oxidoreductase) is responsible for the inhibitor-insensitive succinate-dependent chromate-reductase activity of SMPs. Since chromium(VI) is effectively metabolized by electron transport chain complexes of the mitochondrial inner membrane in vitro, and chromium(V) is formed as an intermediate in the process, mitochondria may play a role in chromium(VI) carcinogenesis.","Chromium(V) is produced upon reduction of chromate by mitochondrial electron transport chain complexes Abs: Incubation of chromate with isolated rat liver submitochondrial particles under anaerobic conditions in vitro results in reduction of chromium(VI) and formation of chromium(V). In the presence of NADH, submitochondrial particles (SMPs) were active in reducing chromate as shown by UV-vis spectroscopic studies, and forming a chromium(V) species which was detectable by electron paramagnetic resonance spectroscopy. In the presence of succinate, SMPs were less effective in reducing chromate and forming chromium(V) relative to their NADH-dependent activity. However, SMPs showed a higher rate of oxygen depletion with NADH as compared to succinate as substrate, suggesting that differences in the NADH-dependent versus succinate-dependent chromate-reductase activity of SMPs is probably due to differences in efficiency of electron donation by succinate and NADH. The use of specific electron transport chain inhibitors allowed the sites of chromium(VI) reduction and chromium(V) formation in SMPs to be determined. Rotenone, antimycin and cyanide all produced approximately 40% inhibition of the NADH-dependent chromate-reductase activity. Thus, complex I (NADH:ubiquinone oxidoreductase) appears to be responsible for the inhibitor-insensitive, and complex IV (ferrocytochrome c:oxygen oxidoreductase) for the inhibitor-sensitive NADH-dependent chromium(VI) reduction and chromium(V) formation. Cyanide and antimycin produced approximately 50% inhibition of the succinate-dependent chromate-reductase activity of SMPs, while no detectable inhibition was observed with rotenone. These results confirm the chromate-reductase activity of complex IV, and suggest that complex II (succinate:ubiquinone oxidoreductase) is responsible for the inhibitor-insensitive succinate-dependent chromate-reductase activity of SMPs. Since chromium(VI) is effectively metabolized by electron transport chain complexes of the mitochondrial inner membrane in vitro, and chromium(V) is formed as an intermediate in the process, mitochondria may play a role in chromium(VI) carcinogenesis."
1235915,Hartwig and  Beyersmann 1989,Comutagenicity and inhibition of DNA repair by metal ions in mammalian cells,"Mutagenic and/or carcinogenic metal compounds may act directly by interaction with DNA and/or indirectly by interference with genetic control and repair mechanisms. In a previous report, we investigated the mutagenicity and comutagenicity of nickel(II) in the V79 Chinese hamster HGPRT-assay. Our present findings demonstrate that like nickel(II), chromium(VI) and cadmium(II) are also comutagenic with UV. Furthermore, there is only a weak concordance with comutagenic effects observed in bacterial test systems. In the case of nickel(II), there is a good correlation between comutagenicity and inhibition of DNA repair, as determined by using the nucleoid sedimentation technique with HeLa cells. This inhibition may occur via replacement of other divalent ions essential in repair enzymes.","Comutagenicity and inhibition of DNA repair by metal ions in mammalian cells Abs: Mutagenic and/or carcinogenic metal compounds may act directly by interaction with DNA and/or indirectly by interference with genetic control and repair mechanisms. In a previous report, we investigated the mutagenicity and comutagenicity of nickel(II) in the V79 Chinese hamster HGPRT-assay. Our present findings demonstrate that like nickel(II), chromium(VI) and cadmium(II) are also comutagenic with UV. Furthermore, there is only a weak concordance with comutagenic effects observed in bacterial test systems. In the case of nickel(II), there is a good correlation between comutagenicity and inhibition of DNA repair, as determined by using the nucleoid sedimentation technique with HeLa cells. This inhibition may occur via replacement of other divalent ions essential in repair enzymes."
1235914,Sugiyama 1989,Effects of vitamin E and vitamin B2 on chromate-induced DNA lesions,"The induction of DNA single strand breaks by carcinogenic chromate compounds has been found to be altered by vitamin E and vitamin B2. Pretreatment with vitamin E for 24 h prior to exposure to Na2CrO4 resulted in a decrease of chromate-induced DNA single strand breaks, whereas similar treatment with vitamin B2 enhanced levels of breaks induced by chromate. In contrast, levels of DNA protein crosslinks, the other major lesion induced, were not affected by vitamin E or vitamin B2. The uptake of Na2CrO4 was not affected by pretreatment with these vitamins. The role of vitamins in chromate-induced DNA damages is discussed.","Effects of vitamin E and vitamin B2 on chromate-induced DNA lesions Abs: The induction of DNA single strand breaks by carcinogenic chromate compounds has been found to be altered by vitamin E and vitamin B2. Pretreatment with vitamin E for 24 h prior to exposure to Na2CrO4 resulted in a decrease of chromate-induced DNA single strand breaks, whereas similar treatment with vitamin B2 enhanced levels of breaks induced by chromate. In contrast, levels of DNA protein crosslinks, the other major lesion induced, were not affected by vitamin E or vitamin B2. The uptake of Na2CrO4 was not affected by pretreatment with these vitamins. The role of vitamins in chromate-induced DNA damages is discussed."
1235910,Pietrzak et al. 1989,"Splanchnic volume, not flow rate, determines peritoneal permeability","To distinguish the effects of splanchnic blood flow rate from those of splanchnic volume on peritoneal transfer rates, measurements were made in rabbits before and after intraperitoneal exposure to sodium chromate. The sodium chromate induced reversible hepatic sinusoidal block with consequent portal venous congestion and stasis, which was demonstrable on histologic sections. Concurrently the ultrafiltration rate, and ultrafiltration coefficient each doubled after chromium even though the dialysate reabsorptive rate increased and the absorptive diffusion of glucose was at least as high as in control dialyses. Chromium induced significant increases in mass transfer coefficients of urea, potassium and phosphate and in protein clearance. These data suggest that splanchnic volume is an important determinant of peritoneal transfer functions and that the hepatic capillaries may contribute appreciably to transfer ordinarily ascribed to peritoneal capillaries alone.","Splanchnic volume, not flow rate, determines peritoneal permeability Abs: To distinguish the effects of splanchnic blood flow rate from those of splanchnic volume on peritoneal transfer rates, measurements were made in rabbits before and after intraperitoneal exposure to sodium chromate. The sodium chromate induced reversible hepatic sinusoidal block with consequent portal venous congestion and stasis, which was demonstrable on histologic sections. Concurrently the ultrafiltration rate, and ultrafiltration coefficient each doubled after chromium even though the dialysate reabsorptive rate increased and the absorptive diffusion of glucose was at least as high as in control dialyses. Chromium induced significant increases in mass transfer coefficients of urea, potassium and phosphate and in protein clearance. These data suggest that splanchnic volume is an important determinant of peritoneal transfer functions and that the hepatic capillaries may contribute appreciably to transfer ordinarily ascribed to peritoneal capillaries alone."
1235908,Mac et al. 1989,Preparation and characterization of poly(styrene) microcapsules containing corrosion inhibitors,"A technique has been developed to view cross-sections of microcapsules prepared by a multiple emulsion method. Poly(styrene) microcapsules were prepared by emulsifying an aqueous solution containing sodium dichromate, a corrosion inhibitor, into an organic solution containing dissolved poly(styrene). This water-in-oil emulsion was added to an aqueous solution with stirring to form a water-in-oil-in-water emulsion. The organic solvent was removed under reduced pressure resulting in polystyrene walled microcapsules containing aqueous sodium dichromate. The microcapsules were embedded in an agarose gel and sliced for examination by transmission electron microscopy. The cross-sections clearly identified a core surrounded by a sponge-like polymeric wall. The microcapsules were also examined by scanning electron microscopy. These photomicrographs showed a smooth, continuous external wall structure.","Preparation and characterization of poly(styrene) microcapsules containing corrosion inhibitors Abs: A technique has been developed to view cross-sections of microcapsules prepared by a multiple emulsion method. Poly(styrene) microcapsules were prepared by emulsifying an aqueous solution containing sodium dichromate, a corrosion inhibitor, into an organic solution containing dissolved poly(styrene). This water-in-oil emulsion was added to an aqueous solution with stirring to form a water-in-oil-in-water emulsion. The organic solvent was removed under reduced pressure resulting in polystyrene walled microcapsules containing aqueous sodium dichromate. The microcapsules were embedded in an agarose gel and sliced for examination by transmission electron microscopy. The cross-sections clearly identified a core surrounded by a sponge-like polymeric wall. The microcapsules were also examined by scanning electron microscopy. These photomicrographs showed a smooth, continuous external wall structure."
1235907,Wood and  Lotzová 1989,Adriamycin-induced resistance to natural killer (NK)-mediated cytotoxicity,"Studies were done to determine the susceptibility of a colon carcinoma cell line, LoVo, to natural killer (NK) mediated lysis after exposure to the tumor cells to Adriamycin (ADR) (doxorubicin; Adria Laboratories, Columbus, OH). LoVo cells were exposed to ADR (0.4 micrograms/ml) for various time intervals and then tested for sensitivity to lysis by NK cells from the peripheral blood of normal donors in a sodium chromate (Cr51) release cytotoxicity assay. Exposure of tumor targets to ADR induced a resistance to NK-mediated lysis. Susceptibility to lysis decreased progressively to approximately 60% of control levels after 72 hours of ADR exposure. The induction of resistance was dependent on ADR dose, but did not magnify with doses greater than 0.4 micrograms/ml. When target cells were allowed to recover from ADR in fresh medium for 48 hours, complete reversal of the ADR effect was seen. The effect of interleukin-2 (IL-2) stimulation on the NK lysis of LoVo also was tested. IL-2-stimulated effector cells demonstrated enhanced cytotoxicity to LoVo targets and were able to overcome the ADR-induced resistance to lysis. The mechanism of resistance does not appear to be related to the altered binding of effectors to chemotherapy-treated targets, as suggested by single cell assay results.","Adriamycin-induced resistance to natural killer (NK)-mediated cytotoxicity Abs: Studies were done to determine the susceptibility of a colon carcinoma cell line, LoVo, to natural killer (NK) mediated lysis after exposure to the tumor cells to Adriamycin (ADR) (doxorubicin; Adria Laboratories, Columbus, OH). LoVo cells were exposed to ADR (0.4 micrograms/ml) for various time intervals and then tested for sensitivity to lysis by NK cells from the peripheral blood of normal donors in a sodium chromate (Cr51) release cytotoxicity assay. Exposure of tumor targets to ADR induced a resistance to NK-mediated lysis. Susceptibility to lysis decreased progressively to approximately 60% of control levels after 72 hours of ADR exposure. The induction of resistance was dependent on ADR dose, but did not magnify with doses greater than 0.4 micrograms/ml. When target cells were allowed to recover from ADR in fresh medium for 48 hours, complete reversal of the ADR effect was seen. The effect of interleukin-2 (IL-2) stimulation on the NK lysis of LoVo also was tested. IL-2-stimulated effector cells demonstrated enhanced cytotoxicity to LoVo targets and were able to overcome the ADR-induced resistance to lysis. The mechanism of resistance does not appear to be related to the altered binding of effectors to chemotherapy-treated targets, as suggested by single cell assay results."
1235906,Petruzzelli et al. 1989,Carcinogen metabolism studies in human bronchial and lung parenchymal tissues,"The pulmonary metabolism of xenobiotics was investigated by measuring the glutathione content and the activity of the aryl hydrocarbon hydroxylase, epoxide hydrolase, glutathione S-transferase, and uridine 5' -diphosphoglucuronosyl transferase enzymes in S-12 fractions of bronchial tree and peripheral lung parenchyma obtained at surgery from 21 patients. In parallel, the same preparations were used to assess either the activation of promutagens, i.e., benzo(a)pyrene, 2-aminofluorene, cyclophosphamide, and a cigarette smoke condensate, to metabolites reverting his- Salmonella typhymurium strains, or the decrease of direct-acting mutagens, i.e., sodium dichromate, 4-nitroquinoline N-oxide, epichlorohydrin, and ICR 191. As compared to bronchus preparations, parenchymal preparations contained considerably higher concentrations of reduced glutathione, had a significantly higher epoxide hydrolase activity, and, as assessed by means of a quantitative index, were more efficient in activating 2-aminofluorene and in reducing the mutagenicity of dichromate and 4-nitroquinoline N-oxide. These data may suggest that parenchymal lung tissue is more capable than bronchial tissue to detoxify reactive intermediates of xenobiotics, possibly explaining the greater susceptibility of bronchi to cigarette smoke-induced cancers.","Carcinogen metabolism studies in human bronchial and lung parenchymal tissues Abs: The pulmonary metabolism of xenobiotics was investigated by measuring the glutathione content and the activity of the aryl hydrocarbon hydroxylase, epoxide hydrolase, glutathione S-transferase, and uridine 5' -diphosphoglucuronosyl transferase enzymes in S-12 fractions of bronchial tree and peripheral lung parenchyma obtained at surgery from 21 patients. In parallel, the same preparations were used to assess either the activation of promutagens, i.e., benzo(a)pyrene, 2-aminofluorene, cyclophosphamide, and a cigarette smoke condensate, to metabolites reverting his- Salmonella typhymurium strains, or the decrease of direct-acting mutagens, i.e., sodium dichromate, 4-nitroquinoline N-oxide, epichlorohydrin, and ICR 191. As compared to bronchus preparations, parenchymal preparations contained considerably higher concentrations of reduced glutathione, had a significantly higher epoxide hydrolase activity, and, as assessed by means of a quantitative index, were more efficient in activating 2-aminofluorene and in reducing the mutagenicity of dichromate and 4-nitroquinoline N-oxide. These data may suggest that parenchymal lung tissue is more capable than bronchial tissue to detoxify reactive intermediates of xenobiotics, possibly explaining the greater susceptibility of bronchi to cigarette smoke-induced cancers."
1235888,Gad 1989,Acute and chronic systemic chromium toxicity,"Although chromium and compounds containing it have been recognized as having potential severe adverse effects on health for more than 160 years, understanding of the systemic toxicology and true hazard of these compounds is still not complete. A review of the current state of knowledge is attempted in this paper, with appropriate attention given to the complications of multiple valence states and solubility. Selected chromium compounds, particularly hexavalent ones, are carcinogens, corrosives, delayed contact sensitizers, and have the kidney as their primary target organ. But chromium is also an essential element for humans. The body clearly possesses some effective detoxification mechanisms for some degree of exposure to hexavalent chrome compounds. The significant features of acute and chronic chromium toxicity are presented in view of these considerations.","Acute and chronic systemic chromium toxicity Abs: Although chromium and compounds containing it have been recognized as having potential severe adverse effects on health for more than 160 years, understanding of the systemic toxicology and true hazard of these compounds is still not complete. A review of the current state of knowledge is attempted in this paper, with appropriate attention given to the complications of multiple valence states and solubility. Selected chromium compounds, particularly hexavalent ones, are carcinogens, corrosives, delayed contact sensitizers, and have the kidney as their primary target organ. But chromium is also an essential element for humans. The body clearly possesses some effective detoxification mechanisms for some degree of exposure to hexavalent chrome compounds. The significant features of acute and chronic chromium toxicity are presented in view of these considerations."
1235887,Heaton et al. 1989,Studies with nonradioisotopic sodium chromate: I. Development of a technique for measuring red cell volume,"A nonradioisotopic method for measuring red cell volume that involves the use of 52Cr-sodium chromate as the red cell label and of graphite furnace atomic absorption analysis of chromium is described. The technique allows the labeling of 20 mL of packed red cells with 40 to 50 ?g of sodium chromate (Na2CrO4) in 30 minutes at 22° C with 94 ± 6 percent uptake. Approximately 40 ?g of Na2CrO4 was injected for in vivo studies. This results in posttransfusion in vivo red cell chromium levels after sample processing in the range of 1 to 7 ?g per L, which could be quantitated accurately (coefficient of variation = 4.7%) by Zeeman electrothermal atomic absorption spectrophotometry. The labeling concentration of chromium did not cause increased hemolysis, and the labeled cells exhibited an osmotic fragility curve similar to that of unlabeled, fresh ACD red cells. Red cell glutathione peroxidase was unaffected by labeling, although glutathione reductase was reduced by approximately 13 percent (p < 0.05). The 52Cr red cell volume-measuring method was evaluated by concurrent in vivo studies with the standard 51Cr and 125I-albumin methods for that procedure. Simultaneous measurement of red cell volumes in seven volunteers by the 51Cr, 52Cr, and 125I-albumin techniques correlated highly with each other (r > 0.76), with mean values of 2294 ± 199, 2191 ± 180, and 2243 ± 291 mL, respectively. The standard deviations of the differences were small: 134 mL for 52Cr versus 51Cr and 183 mL for 52Cr versus 125I. These results indicate that the nonradioisotopic technique gives reliable and accurate red cell volume estimates that are similar to those obtained by the standard methods.","Studies with nonradioisotopic sodium chromate: I. Development of a technique for measuring red cell volume Abs: A nonradioisotopic method for measuring red cell volume that involves the use of 52Cr-sodium chromate as the red cell label and of graphite furnace atomic absorption analysis of chromium is described. The technique allows the labeling of 20 mL of packed red cells with 40 to 50 ?g of sodium chromate (Na2CrO4) in 30 minutes at 22° C with 94 ± 6 percent uptake. Approximately 40 ?g of Na2CrO4 was injected for in vivo studies. This results in posttransfusion in vivo red cell chromium levels after sample processing in the range of 1 to 7 ?g per L, which could be quantitated accurately (coefficient of variation = 4.7%) by Zeeman electrothermal atomic absorption spectrophotometry. The labeling concentration of chromium did not cause increased hemolysis, and the labeled cells exhibited an osmotic fragility curve similar to that of unlabeled, fresh ACD red cells. Red cell glutathione peroxidase was unaffected by labeling, although glutathione reductase was reduced by approximately 13 percent (p < 0.05). The 52Cr red cell volume-measuring method was evaluated by concurrent in vivo studies with the standard 51Cr and 125I-albumin methods for that procedure. Simultaneous measurement of red cell volumes in seven volunteers by the 51Cr, 52Cr, and 125I-albumin techniques correlated highly with each other (r > 0.76), with mean values of 2294 ± 199, 2191 ± 180, and 2243 ± 291 mL, respectively. The standard deviations of the differences were small: 134 mL for 52Cr versus 51Cr and 183 mL for 52Cr versus 125I. These results indicate that the nonradioisotopic technique gives reliable and accurate red cell volume estimates that are similar to those obtained by the standard methods."
1235886,Heaton et al. 1989,Studies with nonradioisotopic sodium chromate: II. Single- and double-label 52Cr/51Cr posttransfusion recovery estimations,"A recently developed nonradioisotopic 52Cr technique was used to measure either red cell volume or posttransfusion recovery of stored red cells. The experimental method uses Zeeman electrothermal atomic absorption spectrophotometry to measure red cell chromium. Results from the 52Cr method were compared with those from 51Cr single-label and 125I-albumin/51Cr double-label procedures using 49-day AS-1 red cell concentrates drawn and prepared according to standard procedures. In the first group of five donors, red cell volume was estimated concurrently with both 52Cr-labeled fresh red cells and 125I-albumin. The latter measured plasma volume from which red cell volume was estimated on the basis of the hematocrit (125I red cell volume). 51Cr-labeled stored red cells were transfused to measure posttransfusion recoveries. The correlation between 52Cr and 125I red cell volumes was significant (r = 0.68, p < 0.01), and, in this group, the differences were not significant (p > 0.05). Twenty-four-hour posttransfusion recoveries of 51Cr-labeled stored red cells averaged 66 ± 5 percent when measured with the 125I/51Cr technique and 69 ± 8 percent when measured with the 52Cr/51Cr method. In the second group of five donors, red cell volume was estimated by the 125I-albumin technique, and the posttransfusion recovery of stored red cells was quantitated by 51Cr- and 52Cr-labeled stored cells simultaneously. In this group, posttransfusion recoveries with 125I/51Cr averaged 73 ± 7 percent; with 125I/52Cr, they averaged 75 ± 10 percent. Using the single-label method of calculation, recoveries averaged 76 ± 7 and 75 ± 10 percent for the 51Cr and 52Cr methods, respectively. Calculated mean posttransfusion recoveries for the total group (n = 10) showed a small but significantly lower (p < 0.05) posttransfusion recovery with the double-label 125I/51Cr technique (69 ± 7%) than that with the single-label 51Cr method (74 ± 7%). The nonradioisotopic 52Cr technique provided an acceptable measure of posttransfusion recovery when used in a double-label method, either for the determination of red cell volume concurrent with 51Cr-labeled stored cells or for the labeling of stored cells with an independent measure of red cell volume.","Studies with nonradioisotopic sodium chromate: II. Single- and double-label 52Cr/51Cr posttransfusion recovery estimations Abs: A recently developed nonradioisotopic 52Cr technique was used to measure either red cell volume or posttransfusion recovery of stored red cells. The experimental method uses Zeeman electrothermal atomic absorption spectrophotometry to measure red cell chromium. Results from the 52Cr method were compared with those from 51Cr single-label and 125I-albumin/51Cr double-label procedures using 49-day AS-1 red cell concentrates drawn and prepared according to standard procedures. In the first group of five donors, red cell volume was estimated concurrently with both 52Cr-labeled fresh red cells and 125I-albumin. The latter measured plasma volume from which red cell volume was estimated on the basis of the hematocrit (125I red cell volume). 51Cr-labeled stored red cells were transfused to measure posttransfusion recoveries. The correlation between 52Cr and 125I red cell volumes was significant (r = 0.68, p < 0.01), and, in this group, the differences were not significant (p > 0.05). Twenty-four-hour posttransfusion recoveries of 51Cr-labeled stored red cells averaged 66 ± 5 percent when measured with the 125I/51Cr technique and 69 ± 8 percent when measured with the 52Cr/51Cr method. In the second group of five donors, red cell volume was estimated by the 125I-albumin technique, and the posttransfusion recovery of stored red cells was quantitated by 51Cr- and 52Cr-labeled stored cells simultaneously. In this group, posttransfusion recoveries with 125I/51Cr averaged 73 ± 7 percent; with 125I/52Cr, they averaged 75 ± 10 percent. Using the single-label method of calculation, recoveries averaged 76 ± 7 and 75 ± 10 percent for the 51Cr and 52Cr methods, respectively. Calculated mean posttransfusion recoveries for the total group (n = 10) showed a small but significantly lower (p < 0.05) posttransfusion recovery with the double-label 125I/51Cr technique (69 ± 7%) than that with the single-label 51Cr method (74 ± 7%). The nonradioisotopic 52Cr technique provided an acceptable measure of posttransfusion recovery when used in a double-label method, either for the determination of red cell volume concurrent with 51Cr-labeled stored cells or for the labeling of stored cells with an independent measure of red cell volume."
1235883,Branca et al. 1989,In vitro interaction of mutagenic chromium (VI) with red blood cells,"The interaction of mutagenic Cr(VI) with red blood cells has been studied by ESR spectroscopy. Signals of two Cr(V) species are observed almost immediately after contacting red cells with chromate(VI) aqueous solution at pH 7.4. The signal at go = 1.985, which decays within one hour, is attributed to a Cr(V) complex formed by glutathione due its reducing and chelating ability. The other signal at go = 1.979, which is distinctly more persistent, may indicate that some immobilization of the formed Cr(V) ions takes place on the macromolecular cell components, e.g. glycoproteins.","In vitro interaction of mutagenic chromium (VI) with red blood cells Abs: The interaction of mutagenic Cr(VI) with red blood cells has been studied by ESR spectroscopy. Signals of two Cr(V) species are observed almost immediately after contacting red cells with chromate(VI) aqueous solution at pH 7.4. The signal at go = 1.985, which decays within one hour, is attributed to a Cr(V) complex formed by glutathione due its reducing and chelating ability. The other signal at go = 1.979, which is distinctly more persistent, may indicate that some immobilization of the formed Cr(V) ions takes place on the macromolecular cell components, e.g. glycoproteins."
1235881,Sugiyama et al. 1989,"Influence of vitamin B2 on formation of chromium(V), alkali-labile sites, and lethality of sodium chromate(VI) in Chinese hamster V-79 cells","The effect of vitamin B2 on the cellular reduction and cytotoxicity of chromate(VI) was studied using Chinese hamster V-79 cells. Electron spin resonance studies showed that incubation of cells with Na2CrO4 resulted in the formation of both chromium(V) and chromium(III) complex and that cellular pretreatment with riboflavin (Vitamin B2) for 24 h prior to exposure increased the level of chromium(V) complex, but the level of chromium(III) remained unchanged. Analysis of flavin derivatives revealed that pretreatment with vitamin B2 increased free riboflavin without altering flavin adenine dinucleotide and flavin mononucleotide. In addition, the level of the flavoenzyme glutathione reductase, which is capable of reducing chromate, was unaffected by pretreatment with vitamin B2. However, treatment of cells with vitamin B2 and Na2CrO4 augmented the inhibition of glutathione reductase attributable to Na2CrO4 alone. Using a colony-forming assay, pretreatment with vitamin B2 resulted in a decrease of cytotoxicity after exposure to the lethal concentration of chromate (15 microM) but did not affect the cytotoxicity at sublethal concentration of this metal (5-7.5 microM). Alkaline elution studies demonstrated that Na2CrO4 induced alkali-labile sites in the DNA of cells in a concentration-dependent manner (5-15 microM) and pretreatment with vitamin B2 resulted in an increase of these DNA lesions at all concentrations of Na2CrO4. The results, showing that vitamin B2 enhances chromate-induced alkali-labile lesions and chromium inhibition of glutathione reductase, might be due to an increase of chromium(V) species, possibly through its ability to directly reduce chromium(VI). The results also suggest that the extent of DNA lesions induced by chromate may not correlate directly with the cytotoxic effects of this metal.","Influence of vitamin B2 on formation of chromium(V), alkali-labile sites, and lethality of sodium chromate(VI) in Chinese hamster V-79 cells Abs: The effect of vitamin B2 on the cellular reduction and cytotoxicity of chromate(VI) was studied using Chinese hamster V-79 cells. Electron spin resonance studies showed that incubation of cells with Na2CrO4 resulted in the formation of both chromium(V) and chromium(III) complex and that cellular pretreatment with riboflavin (Vitamin B2) for 24 h prior to exposure increased the level of chromium(V) complex, but the level of chromium(III) remained unchanged. Analysis of flavin derivatives revealed that pretreatment with vitamin B2 increased free riboflavin without altering flavin adenine dinucleotide and flavin mononucleotide. In addition, the level of the flavoenzyme glutathione reductase, which is capable of reducing chromate, was unaffected by pretreatment with vitamin B2. However, treatment of cells with vitamin B2 and Na2CrO4 augmented the inhibition of glutathione reductase attributable to Na2CrO4 alone. Using a colony-forming assay, pretreatment with vitamin B2 resulted in a decrease of cytotoxicity after exposure to the lethal concentration of chromate (15 microM) but did not affect the cytotoxicity at sublethal concentration of this metal (5-7.5 microM). Alkaline elution studies demonstrated that Na2CrO4 induced alkali-labile sites in the DNA of cells in a concentration-dependent manner (5-15 microM) and pretreatment with vitamin B2 resulted in an increase of these DNA lesions at all concentrations of Na2CrO4. The results, showing that vitamin B2 enhances chromate-induced alkali-labile lesions and chromium inhibition of glutathione reductase, might be due to an increase of chromium(V) species, possibly through its ability to directly reduce chromium(VI). The results also suggest that the extent of DNA lesions induced by chromate may not correlate directly with the cytotoxic effects of this metal."
1235878,Girolami et al. 1989,Inverse relationship between renal and urinary kallikrein during chromate-induced acute renal failure in rat: Urinary kallikrein excretion as a possible recovery index,"Acute renal failure (ARF) was induced in rat following a single injection of sodium chromate. A transient polyuria and a 10-fold decrease in glomerular filtration rate was immediately observed after sodium chromate administration. Urinary sodium and potassium excretion were reduced within 24 h and remained decreased for 8 to 10 days. Progressive recovery of normal renal functions, mainly electrolyte excretion and filtration rate was observed 12 days after sodium chromate administration. Urinary kallikrein excretion (UKE) was decreased only 48 h after sodium chromate administration. However the proportion of the active and inactive form excreted was unchanged. UKE remained also at a reduced level for 8 to 10 days and returned progressively to base-line level. The kallikrein content in the tissue was significantly increased immediately after sodium chromate administration and recovered normal values 12 days later. The increase of kallikrein in the tissue is more likely unspecific due to impaired protein transport than a specific stimulation of renal kallikrein biosynthesis. The decreased UKE may indicate a distal tubular reversible dysfunction in this ARF model. These reductions in electrolyte excretion, glomerular filtration and UKE were associated with selective morphological lesions. Whereas the glomeruli were intact, important damages affected proximal tubule cells which appeared necrotic and showed presence of vacuoles, liquefaction of cytoplasmic material and lost of microvilli. Less marked lesions were however observed in distal tubules, particularly large vacuoles were present at the apical poles of the tubule cells, the sites of kallikrein secretion. These distal damages may be involved in the increase of tissue concentration and in the decrease of UKE.(ABSTRACT TRUNCATED AT 250 WORDS)","Inverse relationship between renal and urinary kallikrein during chromate-induced acute renal failure in rat: Urinary kallikrein excretion as a possible recovery index Abs: Acute renal failure (ARF) was induced in rat following a single injection of sodium chromate. A transient polyuria and a 10-fold decrease in glomerular filtration rate was immediately observed after sodium chromate administration. Urinary sodium and potassium excretion were reduced within 24 h and remained decreased for 8 to 10 days. Progressive recovery of normal renal functions, mainly electrolyte excretion and filtration rate was observed 12 days after sodium chromate administration. Urinary kallikrein excretion (UKE) was decreased only 48 h after sodium chromate administration. However the proportion of the active and inactive form excreted was unchanged. UKE remained also at a reduced level for 8 to 10 days and returned progressively to base-line level. The kallikrein content in the tissue was significantly increased immediately after sodium chromate administration and recovered normal values 12 days later. The increase of kallikrein in the tissue is more likely unspecific due to impaired protein transport than a specific stimulation of renal kallikrein biosynthesis. The decreased UKE may indicate a distal tubular reversible dysfunction in this ARF model. These reductions in electrolyte excretion, glomerular filtration and UKE were associated with selective morphological lesions. Whereas the glomeruli were intact, important damages affected proximal tubule cells which appeared necrotic and showed presence of vacuoles, liquefaction of cytoplasmic material and lost of microvilli. Less marked lesions were however observed in distal tubules, particularly large vacuoles were present at the apical poles of the tubule cells, the sites of kallikrein secretion. These distal damages may be involved in the increase of tissue concentration and in the decrease of UKE.(ABSTRACT TRUNCATED AT 250 WORDS)"
1235877,Bruze et al. 1990,Chromate sensitization and elicitation from cement with iron sulfate,"For some years, iron sulfate has been added to cement manufactured in the Scandinavian countries to prevent sensitization to and elicitation from chromate in cement. Allergic contact dermatitis from chromate is reported here in 3 workers with hand dermatitis and exposure to cement containing iron sulfate. Although iron sulfate had been added to the cement, high chromate concentrations were found in many samples of cement to which these workers were exposed.","Chromate sensitization and elicitation from cement with iron sulfate Abs: For some years, iron sulfate has been added to cement manufactured in the Scandinavian countries to prevent sensitization to and elicitation from chromate in cement. Allergic contact dermatitis from chromate is reported here in 3 workers with hand dermatitis and exposure to cement containing iron sulfate. Although iron sulfate had been added to the cement, high chromate concentrations were found in many samples of cement to which these workers were exposed."
1235876,Fisher and  Ottaway 1990,The kinetics of migration of murine CD4 and CD8 lymphocytes in vivo,"Lymphocytes from the mesenteric lymph nodes (MLN) of mice were enriched for CD4+ and CD8+ T cell populations, labeled with (51Cr) sodium chromate, and transferred to the bloodstream of syngeneic recipients. The time course of migration of the labeled cells from the blood to the secondary lymphoid organs of the recipients was investigated. CD4+ and CD8+ subpopulations differed in their profile of appearance in different lymphoid organs. Computer assisted analysis of the observations was used to obtain quantitative estimates of the rate of clearance of the lymphocytes from the blood into the tissues, and the rate of departure of the cells from the tissues. In the spleen, CD4+ lymphocytes were cleared from the blood about one and one-half times faster than CD8+ lymphocytes, but the CD8+ cells were retained longer. Inguinal nodes (IN), MLN, and Peyer's patches (PP) showed a consistent ability to clear CD4+ cells from the blood at a rate approximately 2.5 x greater than that for CD8+ cells, but the retention of the lymphocytes in these tissues varied with lymphocyte phenotype and the organ concerned. CD4+ lymphocytes were retained longer in PP and MLN than in IN, whereas CD8+ cells were retained longer in IN and MLN nodes than in PP. We conclude that the rate of clearance of lymphocytes into secondary lymphoid organs from the blood varies in a regular way with T cell phenotype and that organ specific sorting of T subpopulations also proceeds after the cells are admitted to the tissues.","The kinetics of migration of murine CD4 and CD8 lymphocytes in vivo Abs: Lymphocytes from the mesenteric lymph nodes (MLN) of mice were enriched for CD4+ and CD8+ T cell populations, labeled with (51Cr) sodium chromate, and transferred to the bloodstream of syngeneic recipients. The time course of migration of the labeled cells from the blood to the secondary lymphoid organs of the recipients was investigated. CD4+ and CD8+ subpopulations differed in their profile of appearance in different lymphoid organs. Computer assisted analysis of the observations was used to obtain quantitative estimates of the rate of clearance of the lymphocytes from the blood into the tissues, and the rate of departure of the cells from the tissues. In the spleen, CD4+ lymphocytes were cleared from the blood about one and one-half times faster than CD8+ lymphocytes, but the CD8+ cells were retained longer. Inguinal nodes (IN), MLN, and Peyer's patches (PP) showed a consistent ability to clear CD4+ cells from the blood at a rate approximately 2.5 x greater than that for CD8+ cells, but the retention of the lymphocytes in these tissues varied with lymphocyte phenotype and the organ concerned. CD4+ lymphocytes were retained longer in PP and MLN than in IN, whereas CD8+ cells were retained longer in IN and MLN nodes than in PP. We conclude that the rate of clearance of lymphocytes into secondary lymphoid organs from the blood varies in a regular way with T cell phenotype and that organ specific sorting of T subpopulations also proceeds after the cells are admitted to the tissues."
1235875,Basse et al. 1990,Comparison between 125IUdR and 51Cr as cell labels in investigations of tumor cell migration,"YAC-1 tumor cells double-labeled with Na2[51Cr]O4 [51Cr] and [125I]iododeoxyuridine [125IUdR] were injected intravenously into Balb/c mice in order to investigate their migration and fate 0-4 h after the injection. Whereas the clearance of tumor cells from the lung tissue was similar as judged with both labels, the kinetics of isotope uptake in the liver were strikingly different. Thus, retention of 51Cr in the liver was very high compared to a much lower and only transient retention of 125I. A higher retention of non-tumor cell-associated 51Cr was also observed in most other organs, resulting in overestimation of the number of viable tumor cells in these organs. Moreover, a marked spontaneous release (greater than 10% after 12 h) makes 51Cr less suitable as a cell label than 125IUdR. On the other hand, we found that the release of 125I from dead cells in vivo depends at least partially on host factors such as macrophages. Consequently, caution must be exerted when tumor cell migration is investigated in animals treated with drugs that might affect the reticuloendothelial system. We conclude that 125IUdR is superior to 51Cr as a cell label for investigation of tumor cell migration in vivo, even though some doubt about the reliability of the number of tumor cells in liver and carcass, predicted by this radiolabel, still remains.","Comparison between 125IUdR and 51Cr as cell labels in investigations of tumor cell migration Abs: YAC-1 tumor cells double-labeled with Na2[51Cr]O4 [51Cr] and [125I]iododeoxyuridine [125IUdR] were injected intravenously into Balb/c mice in order to investigate their migration and fate 0-4 h after the injection. Whereas the clearance of tumor cells from the lung tissue was similar as judged with both labels, the kinetics of isotope uptake in the liver were strikingly different. Thus, retention of 51Cr in the liver was very high compared to a much lower and only transient retention of 125I. A higher retention of non-tumor cell-associated 51Cr was also observed in most other organs, resulting in overestimation of the number of viable tumor cells in these organs. Moreover, a marked spontaneous release (greater than 10% after 12 h) makes 51Cr less suitable as a cell label than 125IUdR. On the other hand, we found that the release of 125I from dead cells in vivo depends at least partially on host factors such as macrophages. Consequently, caution must be exerted when tumor cell migration is investigated in animals treated with drugs that might affect the reticuloendothelial system. We conclude that 125IUdR is superior to 51Cr as a cell label for investigation of tumor cell migration in vivo, even though some doubt about the reliability of the number of tumor cells in liver and carcass, predicted by this radiolabel, still remains."
1235873,Collé et al. 1990,Direct radioimmunoassay of rat cystatin C: increased urinary excretion of this cysteine proteases inhibitor during chromate nephropathy,"Rat cystatin C was purified to apparent homogeneity from rat urine after induction of a tubular dysfunction with sodium chromate. The two-steps purification procedure included a Carboxymethyl-papain affinity chromatography and anion exchange chromatography. The purified protein was identified as rat cystatin C by the following criteria: firstly retained on a Cm-papain affinity column, secondly an apparent molecular weight of 15 kDa and pI of 10.2. Antisera raised in rabbits against our purified rat cystatin C did not cross-react with other urinary proteins such as rat albumin and rat kallikrein, but partially cross-reacted with human cystatin C. A direct radioimmunoassay was developed and it enabled 8.32 fmol/ml of rat cystatin C to be detected. The detection range was between 0.125 and 62.5 ng/ml, with 10% intra-assay variation and 14% inter-assay variation. Physiological rat cystatin C excretion (40 +/- 18 micrograms/24 h) was found by the direct assay. In the chromate-intoxicated rat, urinary excretion increased twenty-fivefold (1017 +/- 391 micrograms/24 h) and returned to normal level one week after intoxication. This RIA will allow the study of rat cystatin C metabolism particularly during renal dysfunction.","Direct radioimmunoassay of rat cystatin C: increased urinary excretion of this cysteine proteases inhibitor during chromate nephropathy Abs: Rat cystatin C was purified to apparent homogeneity from rat urine after induction of a tubular dysfunction with sodium chromate. The two-steps purification procedure included a Carboxymethyl-papain affinity chromatography and anion exchange chromatography. The purified protein was identified as rat cystatin C by the following criteria: firstly retained on a Cm-papain affinity column, secondly an apparent molecular weight of 15 kDa and pI of 10.2. Antisera raised in rabbits against our purified rat cystatin C did not cross-react with other urinary proteins such as rat albumin and rat kallikrein, but partially cross-reacted with human cystatin C. A direct radioimmunoassay was developed and it enabled 8.32 fmol/ml of rat cystatin C to be detected. The detection range was between 0.125 and 62.5 ng/ml, with 10% intra-assay variation and 14% inter-assay variation. Physiological rat cystatin C excretion (40 +/- 18 micrograms/24 h) was found by the direct assay. In the chromate-intoxicated rat, urinary excretion increased twenty-fivefold (1017 +/- 391 micrograms/24 h) and returned to normal level one week after intoxication. This RIA will allow the study of rat cystatin C metabolism particularly during renal dysfunction."
1235872,Bomhard et al. 1990,Determination of urinary glutathione S-transferase and lactate dehydrogenase for differentiation between proximal and distal nephron damage,"Cytosolic glutathione S-transferase (GST) activity is confined to the proximal convoluted and straight tubules. Damage to these parts of the nephron should result in leakage of GST into the urinary space. Lactate dehydrogenase (LDH), in contrast, is more generally distributed along the nephron. Measurement of both enzyme activities could therefore be expected to discriminate between different localizations of nephrotoxicity. To test this hypothesis, we determined both enzyme activities in 24 h urine samples from 10-12 female Sprague-Dawley rats, each treated with single i.p. injections of puromycin aminonucleoside (PAN, 130 mg/kg), Na2 CrO4 10, 20, 30 mg/kg), mercuric chloride (HgCl2, 0.5, 0.75, 1.0 mg/kg), folic acid (125, 350, 375 mg/kg), ethyleneimine (0.5, 2.0, 5.0 microliters/kg). Bovine serum albumin (BSA) was injected by the same method, twice daily on 3 consecutive days (2.5, 7.14 g/kg). The results obtained indicate a characteristic dose- and time-dependent pattern of excreted enzyme activities for each of the tested compounds. In both models with primarily glomerular damage, proximal tubular parts were also affected, as could be demonstrated by increased urinary GST and histopathological changes. Damage, mainly to the S1/S2 segment by 20 or 30 mg Na2 CrO4/kg, resulted in moderate to marked increases in LDH excretion, while GST was only moderately elevated at 30 mg/kg. Extreme increases in GST and LDH output were measured after predominant S3 segment damage after 0.75 and 1.0 mg HgCl2/kg. The distally active compounds, folic acid and ethyleneimine, did not increase GST excretion at lower doses. At the high doses, a small rise in GST excretion indicated some, probably secondary, proximal tubular involvement, which correlated with the histopathological findings in these groups.","Determination of urinary glutathione S-transferase and lactate dehydrogenase for differentiation between proximal and distal nephron damage Abs: Cytosolic glutathione S-transferase (GST) activity is confined to the proximal convoluted and straight tubules. Damage to these parts of the nephron should result in leakage of GST into the urinary space. Lactate dehydrogenase (LDH), in contrast, is more generally distributed along the nephron. Measurement of both enzyme activities could therefore be expected to discriminate between different localizations of nephrotoxicity. To test this hypothesis, we determined both enzyme activities in 24 h urine samples from 10-12 female Sprague-Dawley rats, each treated with single i.p. injections of puromycin aminonucleoside (PAN, 130 mg/kg), Na2 CrO4 10, 20, 30 mg/kg), mercuric chloride (HgCl2, 0.5, 0.75, 1.0 mg/kg), folic acid (125, 350, 375 mg/kg), ethyleneimine (0.5, 2.0, 5.0 microliters/kg). Bovine serum albumin (BSA) was injected by the same method, twice daily on 3 consecutive days (2.5, 7.14 g/kg). The results obtained indicate a characteristic dose- and time-dependent pattern of excreted enzyme activities for each of the tested compounds. In both models with primarily glomerular damage, proximal tubular parts were also affected, as could be demonstrated by increased urinary GST and histopathological changes. Damage, mainly to the S1/S2 segment by 20 or 30 mg Na2 CrO4/kg, resulted in moderate to marked increases in LDH excretion, while GST was only moderately elevated at 30 mg/kg. Extreme increases in GST and LDH output were measured after predominant S3 segment damage after 0.75 and 1.0 mg HgCl2/kg. The distally active compounds, folic acid and ethyleneimine, did not increase GST excretion at lower doses. At the high doses, a small rise in GST excretion indicated some, probably secondary, proximal tubular involvement, which correlated with the histopathological findings in these groups."
1235868,Miller and  Costa 1990,Immunodetection of DNA-protein crosslinks by slot blotting,"Ultraviolet light, formaldehyde, cis-diamminedichloroplatinum(II), chromate (Cr6+), or chromium chloride (Cr3+) under the appropriate conditions caused the formation of DNA-protein crosslinks in intact Chinese hamster ovary (CHO) cells or in cell nuclei. The DNA-protein crosslinks were isolated, applied to nitrocellulose filters, and reacted with antibodies to nuclear proteins. An antiserum to a 97-kD nuclear protein detected p97-DNA complexes in CHO nuclei and cell cultures treated with UV light, cis-Pt and formaldehyde. Exposure to Cr3+ induced p97-DNA crosslinks only in isolated nuclei, while chromate (Cr6+) treatment resulted in significant crosslink formation only in intact cells. Analysis of western blots with the p97 antiserum indicated that crosslinks induced by formaldehyde or ultraviolet light required DNAase I digestion of DNA for migration of the p97 complexes into the gel. In contrast, the 97-kD antigen from the metal-induced crosslinks was released from DNA and resolved in the gel when 2-mercaptoethanol was included in the electrophoresis sample buffer. Assay of slot blots with an antihistone monoclonal antibody indicated that formaldehyde, but not cis-Pt or chromate, crosslinked histones to the DNA. These results illustrate the utility of immuno-slot blots in detecting and characterizing DNA-protein complexes induced by diverse chemical and physical agents.","Immunodetection of DNA-protein crosslinks by slot blotting Abs: Ultraviolet light, formaldehyde, cis-diamminedichloroplatinum(II), chromate (Cr6+), or chromium chloride (Cr3+) under the appropriate conditions caused the formation of DNA-protein crosslinks in intact Chinese hamster ovary (CHO) cells or in cell nuclei. The DNA-protein crosslinks were isolated, applied to nitrocellulose filters, and reacted with antibodies to nuclear proteins. An antiserum to a 97-kD nuclear protein detected p97-DNA complexes in CHO nuclei and cell cultures treated with UV light, cis-Pt and formaldehyde. Exposure to Cr3+ induced p97-DNA crosslinks only in isolated nuclei, while chromate (Cr6+) treatment resulted in significant crosslink formation only in intact cells. Analysis of western blots with the p97 antiserum indicated that crosslinks induced by formaldehyde or ultraviolet light required DNAase I digestion of DNA for migration of the p97 complexes into the gel. In contrast, the 97-kD antigen from the metal-induced crosslinks was released from DNA and resolved in the gel when 2-mercaptoethanol was included in the electrophoresis sample buffer. Assay of slot blots with an antihistone monoclonal antibody indicated that formaldehyde, but not cis-Pt or chromate, crosslinked histones to the DNA. These results illustrate the utility of immuno-slot blots in detecting and characterizing DNA-protein complexes induced by diverse chemical and physical agents."
1235867,Tavéra et al. 1990,Tissue and biological fluid distribution of cysteine proteinases inhibitor: rat cystatin C,,Tissue and biological fluid distribution of cysteine proteinases inhibitor: rat cystatin C Abs: 
1235865,Appenroth et al. 1990,Influence of metyrapone and phenobarbital on sodium dichromate nephrotoxicity in developing rats,"After the administration of equal doses of sodium dichromate, chromium concentrations in the kidney were lower in young than in adult rats. To test the age-dependent sensitivity to the nephrotoxicity of dichromate, young and adult rats were given doses to achieve identical chromium concentrations in the kidney. At equal renal concentrations, young rats had less functional and morphological damage than adult rats. As phenobarbital treatment in young rats enhanced the symptoms of nephrotoxicity and metyrapone treatment in adult rats decreased the symptoms of nephrotoxicity, age-dependent differences in chromate nephrotoxicity may be linked to an increase in the enzymatic reduction of Cr(VI) with age.","Influence of metyrapone and phenobarbital on sodium dichromate nephrotoxicity in developing rats Abs: After the administration of equal doses of sodium dichromate, chromium concentrations in the kidney were lower in young than in adult rats. To test the age-dependent sensitivity to the nephrotoxicity of dichromate, young and adult rats were given doses to achieve identical chromium concentrations in the kidney. At equal renal concentrations, young rats had less functional and morphological damage than adult rats. As phenobarbital treatment in young rats enhanced the symptoms of nephrotoxicity and metyrapone treatment in adult rats decreased the symptoms of nephrotoxicity, age-dependent differences in chromate nephrotoxicity may be linked to an increase in the enzymatic reduction of Cr(VI) with age."
1235862,Morel et al. 1990,Assessment of urinary rat beta 2-microglobulin by enzyme immunoassay,"An enzyme immunoassay (EIA) was developed using unlabelled and peroxidase-labelled rabbit antibodies to assess urinary rat beta 2-microglobulin (beta 2-m) excretion. It consisted in the adsorption of rabbit anti-rat beta 2-m immunoglobulin to a polystyrene surface, the addition of beta 2-m samples or standard and the addition of peroxidase-labelled rabbit anti-rat beta 2-m immunoglobulin. After addition of hydrogen peroxide and o-phenylenediamine, the enzyme activity of the solid phase was measured photometrically at 490 nm. Analytical recovery of pure beta 2-m in urine was 102%. From determinations made on normal female and male rats, the ranges of 24-h urine beta 2-m individually excreted were found to be 0.84-4.77 and 3.7-17.3 micrograms, respectively. The means +/- SEM were 2.49 +/- 0.17 and 10.2 +/- 0.55 micrograms. EIA was of value in evidencing the tubule-damaging properties of sodium chromate and hexachloro-1,3-butadiene in rats.","Assessment of urinary rat beta 2-microglobulin by enzyme immunoassay Abs: An enzyme immunoassay (EIA) was developed using unlabelled and peroxidase-labelled rabbit antibodies to assess urinary rat beta 2-microglobulin (beta 2-m) excretion. It consisted in the adsorption of rabbit anti-rat beta 2-m immunoglobulin to a polystyrene surface, the addition of beta 2-m samples or standard and the addition of peroxidase-labelled rabbit anti-rat beta 2-m immunoglobulin. After addition of hydrogen peroxide and o-phenylenediamine, the enzyme activity of the solid phase was measured photometrically at 490 nm. Analytical recovery of pure beta 2-m in urine was 102%. From determinations made on normal female and male rats, the ranges of 24-h urine beta 2-m individually excreted were found to be 0.84-4.77 and 3.7-17.3 micrograms, respectively. The means +/- SEM were 2.49 +/- 0.17 and 10.2 +/- 0.55 micrograms. EIA was of value in evidencing the tubule-damaging properties of sodium chromate and hexachloro-1,3-butadiene in rats."
1235859,Appenroth and  Kersten 1990,The activity of chromate reduction in renal tissue corresponds to chromate nephrotoxicity--developmental aspects,,The activity of chromate reduction in renal tissue corresponds to chromate nephrotoxicity--developmental aspects Abs: 
1235858,Berndt and  Ansari 1990,Nephrotoxicity of metals: effects on plasma membrane function,"Investigations were conducted in part to demonstrate the temporal relationships associated with the administration of metal nephrotoxicants as they affect membrane function. Two types of experiments were undertaken. First, fresh membrane vesicles were isolated from healthy rats and membrane transport assessed. Secondly, membrane vesicles were isolated at various times after the administration of the nephrotoxic metals, but long before the onset of a full blown acute tubular necrosis and acute renal failure. For the initial experiments, a large nephrotoxic dose of mercuric-chloride (7487947) (4mg/kg) was used and the rats were sacrificed at 1, 3, 16, or 48 hours after treatment. Mercuric-chloride failed to alter carbon-14-p-aminohippurate (PAH) transport by basolateral vesicles at any of the times investigated. No effect was noted on glucose transport by brush border vesicles at the two earlier times. At 16 hours glucose transport was markedly reduced. By 48 hours, glucose transport had recovered to a significant degree. The preliminary experiments with sodium-chromate (7775113) were even more dramatic with PAH transport significantly depressed as early as 3 hours. Glucose transport still demonstrated a highly significant over shoot. The authors conclude that all of the data suggest a selective action of metals on membrane function. The early onset of these activities suggests the possibility that membrane damage may be an initiating event in the production of tubular cell necrosis.","Nephrotoxicity of metals: effects on plasma membrane function Abs: Investigations were conducted in part to demonstrate the temporal relationships associated with the administration of metal nephrotoxicants as they affect membrane function. Two types of experiments were undertaken. First, fresh membrane vesicles were isolated from healthy rats and membrane transport assessed. Secondly, membrane vesicles were isolated at various times after the administration of the nephrotoxic metals, but long before the onset of a full blown acute tubular necrosis and acute renal failure. For the initial experiments, a large nephrotoxic dose of mercuric-chloride (7487947) (4mg/kg) was used and the rats were sacrificed at 1, 3, 16, or 48 hours after treatment. Mercuric-chloride failed to alter carbon-14-p-aminohippurate (PAH) transport by basolateral vesicles at any of the times investigated. No effect was noted on glucose transport by brush border vesicles at the two earlier times. At 16 hours glucose transport was markedly reduced. By 48 hours, glucose transport had recovered to a significant degree. The preliminary experiments with sodium-chromate (7775113) were even more dramatic with PAH transport significantly depressed as early as 3 hours. Glucose transport still demonstrated a highly significant over shoot. The authors conclude that all of the data suggest a selective action of metals on membrane function. The early onset of these activities suggests the possibility that membrane damage may be an initiating event in the production of tubular cell necrosis."
1235854,Kim and  Na 1991,Nephrotoxicity of sodium dichromate depending on the route of administration,"A comparison of the effects of intraperitoneal and subcutaneous routes of administration of sodium dichromate on nephrotoxicity in rats was studied. Dichromate when injected subcutaneously (SC group) produced a higher degree of nephrotoxicity than when administered intraperitoneally (IP group). It caused severe progressive proteinuria followed by polyuria and glucosuria, reaching maximum levels at 3 days after treatment in the SC group, whereas it produced mild proteinuria without glucosuria in the IP group. The dose-dependent increases in blood urea nitrogen (BUN) and creatinine concentrations, shown in the SC group, were not observed in the IP group. However, between the two groups, there were no great differences in either the urinary excretion rate of chromium or the electrophoretic patterns of urinary protein in the day 1 urine specimens. Pretreatment of phenobarbital (PB) had no remarkable effect on the dichromate-induced nephrotoxicity. In contrast, it potentiated dichromate-induced hepatotoxicity, the indices of which were the elevation in serum alanine aminotransferase (ALT) activity and hepatic lipid peroxide formation. These results suggest that the dependence of dichromate-induced nephrotoxicity on the route of administration is related to the chemical forms of chromium reaching the kidney, and the necrotizing property of dichromate results from its metabolic fate in vivo.","Nephrotoxicity of sodium dichromate depending on the route of administration Abs: A comparison of the effects of intraperitoneal and subcutaneous routes of administration of sodium dichromate on nephrotoxicity in rats was studied. Dichromate when injected subcutaneously (SC group) produced a higher degree of nephrotoxicity than when administered intraperitoneally (IP group). It caused severe progressive proteinuria followed by polyuria and glucosuria, reaching maximum levels at 3 days after treatment in the SC group, whereas it produced mild proteinuria without glucosuria in the IP group. The dose-dependent increases in blood urea nitrogen (BUN) and creatinine concentrations, shown in the SC group, were not observed in the IP group. However, between the two groups, there were no great differences in either the urinary excretion rate of chromium or the electrophoretic patterns of urinary protein in the day 1 urine specimens. Pretreatment of phenobarbital (PB) had no remarkable effect on the dichromate-induced nephrotoxicity. In contrast, it potentiated dichromate-induced hepatotoxicity, the indices of which were the elevation in serum alanine aminotransferase (ALT) activity and hepatic lipid peroxide formation. These results suggest that the dependence of dichromate-induced nephrotoxicity on the route of administration is related to the chemical forms of chromium reaching the kidney, and the necrotizing property of dichromate results from its metabolic fate in vivo."
1235851,Diop et al. 1991,CRF triggers the CNS release of TRH in stress-induced changes in gastric emptying,"Stress elicited by exposure to cold induces an increase of gastric emptying (GE) and intestinal transit of a caloric meal in mice and the release of corticotropin-releasing factor (CRF) and thyrotropin-releasing hormone (TRH) in the central nervous system (CNS). The present study proposed 1) to compare in mice the central effects of TRH, CRF, and cold-exposure stress on GE and intestinal transit of a caloric test meal consisting of 0.5 ml of reconstituted milk marked with 51Cr-labeled sodium chromate, and 2) using CRF and TRH antisera to determine whether TRH and CRF act in cascade or independently. The intracerebroventricular (icv) injection of TRH (0.5 microgram/kg) and CRF (1 microgram/kg), as well as cold stress, significantly increased GE, whereas 10-fold higher doses injected intraperitoneally were ineffective. The effect of cold stress on GE was abolished by prior icv injection of both CRF and TRH antisera. The effect of TRH was not blocked by CRF antiserum, but TRH antiserum suppressed the increase in GE induced by CRF. Moreover, both CRF and TRH antisera abolished changes in the rate of GE induced by exogenous CRF and TRH injection, respectively, therefore demonstrating the specific efficiency of immunoneutralization. CRF and cold stress both induced an increase in the rate of intestinal transit, while TRH had no effect. Antibodies to CRF prevented the intestinal stimulatory effect induced by CRF and cold stress. In contrast, antibodies to TRH were unable to antagonize either CRF or cold-stress induced increase in the rate of intestinal transit.(ABSTRACT TRUNCATED AT 250 WORDS)","CRF triggers the CNS release of TRH in stress-induced changes in gastric emptying Abs: Stress elicited by exposure to cold induces an increase of gastric emptying (GE) and intestinal transit of a caloric meal in mice and the release of corticotropin-releasing factor (CRF) and thyrotropin-releasing hormone (TRH) in the central nervous system (CNS). The present study proposed 1) to compare in mice the central effects of TRH, CRF, and cold-exposure stress on GE and intestinal transit of a caloric test meal consisting of 0.5 ml of reconstituted milk marked with 51Cr-labeled sodium chromate, and 2) using CRF and TRH antisera to determine whether TRH and CRF act in cascade or independently. The intracerebroventricular (icv) injection of TRH (0.5 microgram/kg) and CRF (1 microgram/kg), as well as cold stress, significantly increased GE, whereas 10-fold higher doses injected intraperitoneally were ineffective. The effect of cold stress on GE was abolished by prior icv injection of both CRF and TRH antisera. The effect of TRH was not blocked by CRF antiserum, but TRH antiserum suppressed the increase in GE induced by CRF. Moreover, both CRF and TRH antisera abolished changes in the rate of GE induced by exogenous CRF and TRH injection, respectively, therefore demonstrating the specific efficiency of immunoneutralization. CRF and cold stress both induced an increase in the rate of intestinal transit, while TRH had no effect. Antibodies to CRF prevented the intestinal stimulatory effect induced by CRF and cold stress. In contrast, antibodies to TRH were unable to antagonize either CRF or cold-stress induced increase in the rate of intestinal transit.(ABSTRACT TRUNCATED AT 250 WORDS)"
1235850,Popper and  Woldrich 1991,Oxygen radical formation a probable mechanism for chromate toxicity,,Oxygen radical formation a probable mechanism for chromate toxicity Abs: 
1235847,Sugiyama et al. 1991,"Effect of ascorbic acid on DNA damage, cytotoxicity, glutathione reductase, and formation of paramagnetic chromium in Chinese hamster V-79 cells treated with sodium chromate(VI)","The effect of pretreatment with ascorbic acid (vitamin C) on chromate-induced DNA damage, cytotoxicity, and enzyme inhibition as well as on the cellular reduction of chromium(VI) was investigated using Chinese hamster V-79 cells. Cellular pretreatment with nontoxic levels of 1 mM ascorbic acid for 24 h prior to exposure resulted in a significant increase (1.7-fold) in cellular levels of this vitamin. Alkaline elution assays demonstrated that this pretreatment decreased cellular levels of Na2CrO4-induced alkali-labile sites while the numbers of DNA-protein crosslinks produced by chromate increased. In colony-forming assays, pretreatment with ascorbic acid enhanced the cytotoxicity of chromate. However, the inhibition of glutathione reductase attributed to Na2CrO4 was attenuated by this pretreatment. Under the same experimental condition, the uptake of chromate in pretreated cells was found to increase. ESR studies revealed that cellular pretreatment with ascorbic acid reduced the level of chromium(V) intermediate and increased the level of chromium(III) complex, indicating that cellular reduction of chromium(VI) to chromium(III) was accelerated by this vitamin. These results suggest that ascorbic acid decreases chromate-induced alkali-labile sites and chromium inhibition of glutathione reductase, but it enhances DNA-protein cross-links and cytotoxicity caused by this metal through its ability to directly reduce chromium(VI).","Effect of ascorbic acid on DNA damage, cytotoxicity, glutathione reductase, and formation of paramagnetic chromium in Chinese hamster V-79 cells treated with sodium chromate(VI) Abs: The effect of pretreatment with ascorbic acid (vitamin C) on chromate-induced DNA damage, cytotoxicity, and enzyme inhibition as well as on the cellular reduction of chromium(VI) was investigated using Chinese hamster V-79 cells. Cellular pretreatment with nontoxic levels of 1 mM ascorbic acid for 24 h prior to exposure resulted in a significant increase (1.7-fold) in cellular levels of this vitamin. Alkaline elution assays demonstrated that this pretreatment decreased cellular levels of Na2CrO4-induced alkali-labile sites while the numbers of DNA-protein crosslinks produced by chromate increased. In colony-forming assays, pretreatment with ascorbic acid enhanced the cytotoxicity of chromate. However, the inhibition of glutathione reductase attributed to Na2CrO4 was attenuated by this pretreatment. Under the same experimental condition, the uptake of chromate in pretreated cells was found to increase. ESR studies revealed that cellular pretreatment with ascorbic acid reduced the level of chromium(V) intermediate and increased the level of chromium(III) complex, indicating that cellular reduction of chromium(VI) to chromium(III) was accelerated by this vitamin. These results suggest that ascorbic acid decreases chromate-induced alkali-labile sites and chromium inhibition of glutathione reductase, but it enhances DNA-protein cross-links and cytotoxicity caused by this metal through its ability to directly reduce chromium(VI)."
1235846,Pelton et al. 1991,Lymphokine-activated killer cell suppressor factor in malignant effusions,"We examined the possibility that tumor-released products inhibit lymphokine-activated killer cell activation. Lymphokine-activated killer cells from human peripheral blood lymphocytes were activated with recombinant interleukin 2 for 4 days in the presence of malignant effusions or conditioned media from cultured cell lines (10% vol/vol). Eight of 10 malignant effusions/media suppressed the induction of lymphokine-activated killer cell cytotoxicity, as measured in a 4-hour sodium chromate release assay. Seven of 10 effusions/media inhibited lymphokine-activated killer cell proliferation. Suppression was both dose and time dependent. A representative suppressive effusion was fractionated by agarose gel chromatography, treated with detergents disruptive of ionic bonds and lipids, and refractionated using polyacrylamide gel chromatography. Seven suppressive fractions ranging in molecular weight from 1 x 10(5) to 3 x 10(5) d were isolated. It is speculated that this suppressor factor may represent a large multimeric structure with ionic-bonded individual suppressive components.","Lymphokine-activated killer cell suppressor factor in malignant effusions Abs: We examined the possibility that tumor-released products inhibit lymphokine-activated killer cell activation. Lymphokine-activated killer cells from human peripheral blood lymphocytes were activated with recombinant interleukin 2 for 4 days in the presence of malignant effusions or conditioned media from cultured cell lines (10% vol/vol). Eight of 10 malignant effusions/media suppressed the induction of lymphokine-activated killer cell cytotoxicity, as measured in a 4-hour sodium chromate release assay. Seven of 10 effusions/media inhibited lymphokine-activated killer cell proliferation. Suppression was both dose and time dependent. A representative suppressive effusion was fractionated by agarose gel chromatography, treated with detergents disruptive of ionic bonds and lipids, and refractionated using polyacrylamide gel chromatography. Seven suppressive fractions ranging in molecular weight from 1 x 10(5) to 3 x 10(5) d were isolated. It is speculated that this suppressor factor may represent a large multimeric structure with ionic-bonded individual suppressive components."
1235845,Jones et al. 1991,Evidence for the generation of hydroxyl radicals from a chromium(V) intermediate isolated from the reaction of chromate with glutathione,"The formation of hydroxyl radicals from a chromium(V) complex isolated from the reaction of glutathione with chromate has been demonstrated in spin trapping experiments using dimethylsulfoxide and 3,5-dibromo-4-nitrosobenzene sulfonate. Mechanisms for the formation of radicals in such systems are discussed. These results help to explain the ability of solutions containing chromate and glutathione to cause strand breaks in DNA.","Evidence for the generation of hydroxyl radicals from a chromium(V) intermediate isolated from the reaction of chromate with glutathione Abs: The formation of hydroxyl radicals from a chromium(V) complex isolated from the reaction of glutathione with chromate has been demonstrated in spin trapping experiments using dimethylsulfoxide and 3,5-dibromo-4-nitrosobenzene sulfonate. Mechanisms for the formation of radicals in such systems are discussed. These results help to explain the ability of solutions containing chromate and glutathione to cause strand breaks in DNA."
1235827,Braude et al. 1955,Studies with radioactive endotoxin. II. Correlation of physiologic effects with distribution of radioactivity in rabbits injected with radioactive sodium chromate,,Studies with radioactive endotoxin. II. Correlation of physiologic effects with distribution of radioactivity in rabbits injected with radioactive sodium chromate Abs: 
1235815,Jones et al. 1955,Decreased red cell survival associated with liver disease; use of radioactive sodium chromate in measurement of red cell survival,,Decreased red cell survival associated with liver disease; use of radioactive sodium chromate in measurement of red cell survival Abs: 
1235811,Weinstein et al. 1954,Radioactive sodium chromate for the study of survival of red blood cells. III. The abnormal hemoglobin syndromes,,Radioactive sodium chromate for the study of survival of red blood cells. III. The abnormal hemoglobin syndromes Abs: 
1235806,Read et al. 1954,The use of radioactive sodium chromate to evaluate the life span of the red blood cell in health and certain hematologic disorders,,The use of radioactive sodium chromate to evaluate the life span of the red blood cell in health and certain hematologic disorders Abs: 
1235797,Gray and  Frank 1953,The simultaneous determination of red cell mass and plasma volume in man with radioactive sodium chromate and chromic chloride,,The simultaneous determination of red cell mass and plasma volume in man with radioactive sodium chromate and chromic chloride Abs: 
1235795,Weinstein and  Leroy 1953,Radioactive sodium chromate for the study of survival of red blood cells. II. The rate of hemolysis in certain hematologic disorders,,Radioactive sodium chromate for the study of survival of red blood cells. II. The rate of hemolysis in certain hematologic disorders Abs: 
1235794,Necheles et al. 1953,Radioactive sodium chromate for the study of survival of red blood cells. I. The effect of radioactive sodium chromate on red cells,,Radioactive sodium chromate for the study of survival of red blood cells. I. The effect of radioactive sodium chromate on red cells Abs: 
1235777,Koets 1952,The effect of heat inactivation on precipitation of serum proteins by means of sodium chromate in sera of normal and cancerous subjects,,The effect of heat inactivation on precipitation of serum proteins by means of sodium chromate in sera of normal and cancerous subjects Abs: 
1235763,Hall 1945,Contact dermatitis due to pigment in zinc chromate primer,,Contact dermatitis due to pigment in zinc chromate primer Abs: 
1235762,Hall 1945,Contact dermatitis due to the resinous ingredients of zinc chromate primer and certain lacquers,,Contact dermatitis due to the resinous ingredients of zinc chromate primer and certain lacquers Abs: 
1235761,Northrop 1929,UNEQUAL DISTRIBUTION OF IONS IN A COLLODION CELL,The properties of dry collodion membranes previously described allow the prediction that cells of these membranes will concentrate solutes under certain conditions. Three such cases have been studied experimentally. 1. A membrane containing thiosulphate and immersed in a solution of iodine concentrates iodide ion. 2. A membrane containing sodium chromate and immersed in mercury chloride concentrates chloride ion. 3. A membrane containing calcium carbonate and immersed in acetic acid concentrates acetate ions.,UNEQUAL DISTRIBUTION OF IONS IN A COLLODION CELL Abs: The properties of dry collodion membranes previously described allow the prediction that cells of these membranes will concentrate solutes under certain conditions. Three such cases have been studied experimentally. 1. A membrane containing thiosulphate and immersed in a solution of iodine concentrates iodide ion. 2. A membrane containing sodium chromate and immersed in mercury chloride concentrates chloride ion. 3. A membrane containing calcium carbonate and immersed in acetic acid concentrates acetate ions.
1235752,Sugiyama et al. 1991,Protective effect of vitamin E against chromosomal aberrations and mutation induced by sodium chromate in Chinese hamster V79 cells,"The effect of vitamin E on chromosomal aberrations and mutation caused by Na2CrO4 was investigated in Chinese hamster V79 cells. Pretreatment with 25 microM alpha-tocopherol succinate (vitamin E) for 24 h prior to chromate exposure (2.5-5 microM) resulted in a decrease of metal-induced chromosomal aberrations. Na2CrO4 (2.5-7.5 microM) induced mutations at the HGPRT locus, but only within a very limited concentration range. This mutagenic response could also be suppressed by pretreatment with vitamin E. These results suggest that vitamin E can protect cells from the clastogenic and mutagenic action of chromate compounds, possibly through its ability to scavenge chromium(V) and/or free radicals.","Protective effect of vitamin E against chromosomal aberrations and mutation induced by sodium chromate in Chinese hamster V79 cells Abs: The effect of vitamin E on chromosomal aberrations and mutation caused by Na2CrO4 was investigated in Chinese hamster V79 cells. Pretreatment with 25 microM alpha-tocopherol succinate (vitamin E) for 24 h prior to chromate exposure (2.5-5 microM) resulted in a decrease of metal-induced chromosomal aberrations. Na2CrO4 (2.5-7.5 microM) induced mutations at the HGPRT locus, but only within a very limited concentration range. This mutagenic response could also be suppressed by pretreatment with vitamin E. These results suggest that vitamin E can protect cells from the clastogenic and mutagenic action of chromate compounds, possibly through its ability to scavenge chromium(V) and/or free radicals."
1235751,Mikalsen et al. 1991,"Effect of in vivo chromate, acetone and combined treatment on rat liver in vitro microsomal chromium(VI) reductive activity and on cytochrome P450 expression","Cytochrome P450 (P450IIE1) in rat has previously been shown to exhibit high chromate [Cr(VI)] reductase activity (Mikalsen et al. 1991). The present study reports on the effect of chromate treatment in vivo in rats and on the modulating effect of acetone + fasting on chromium(VI) toxicity. No effect of intraperitoneal injection with 5 mg chromate/kg was observed, whereas 15 mg chromate/kg decreased the liver microsomal Cr(VI) reductase activity by about 30% in in vitro microsomal incubations. In addition, the P450 and cytochrome b5 contents were decreased by about 30% and 25% respectively. Acetone + fasting caused increases of total microsomal P450 and cytochrome b5 contents, associated with similar increases in apoproteins P450IIE1 and P450IIB1 + 2, and their corresponding mRNA, and apoprotein NADPH-P450 reductase, as well as NADPH-P450 reductase and microsomal Cr(VI) reductive activities. Related to acetone + fasting alone, when given in combination with chromate (15 mg/kg) the Cr(VI) reductive activity was decreased by about 30%, associated with decreases in the P450 and cytochrome b5 contents, 65% and 35% respectively. This further reduced the apoprotein levels of P450IIB1 + 2, P450IIE1, and NADPH-P450 reductase to 90%, 60%, and 40%, respectively, and the mRNA levels of P450IIB2 and P450IIE1. No effect was observed on NADPH-P450 reductase activity. This dose also caused some macroscopic alterations in the liver. In contrast, the P450IIE1 apoprotein level in the lung was apparently stabilized or even increased by chromate in rats treated with acetone + fasting.(ABSTRACT TRUNCATED AT 250 WORDS)","Effect of in vivo chromate, acetone and combined treatment on rat liver in vitro microsomal chromium(VI) reductive activity and on cytochrome P450 expression Abs: Cytochrome P450 (P450IIE1) in rat has previously been shown to exhibit high chromate [Cr(VI)] reductase activity (Mikalsen et al. 1991). The present study reports on the effect of chromate treatment in vivo in rats and on the modulating effect of acetone + fasting on chromium(VI) toxicity. No effect of intraperitoneal injection with 5 mg chromate/kg was observed, whereas 15 mg chromate/kg decreased the liver microsomal Cr(VI) reductase activity by about 30% in in vitro microsomal incubations. In addition, the P450 and cytochrome b5 contents were decreased by about 30% and 25% respectively. Acetone + fasting caused increases of total microsomal P450 and cytochrome b5 contents, associated with similar increases in apoproteins P450IIE1 and P450IIB1 + 2, and their corresponding mRNA, and apoprotein NADPH-P450 reductase, as well as NADPH-P450 reductase and microsomal Cr(VI) reductive activities. Related to acetone + fasting alone, when given in combination with chromate (15 mg/kg) the Cr(VI) reductive activity was decreased by about 30%, associated with decreases in the P450 and cytochrome b5 contents, 65% and 35% respectively. This further reduced the apoprotein levels of P450IIB1 + 2, P450IIE1, and NADPH-P450 reductase to 90%, 60%, and 40%, respectively, and the mRNA levels of P450IIB2 and P450IIE1. No effect was observed on NADPH-P450 reductase activity. This dose also caused some macroscopic alterations in the liver. In contrast, the P450IIE1 apoprotein level in the lung was apparently stabilized or even increased by chromate in rats treated with acetone + fasting.(ABSTRACT TRUNCATED AT 250 WORDS)"
1235750,Standeven and  Wetterhahn 1991,Possible role of glutathione in chromium(VI) metabolism and toxicity in rats,"The effect of Cr(VI) on liver, kidney, and lung glutathione (GSH) levels and the effect of GSH depletion on Cr(VI)-induced nephrotoxicity were studied in male Sprague-Dawley rats (150-200 g). GSH levels, measured as nonprotein sulfhydryls, were determined between 0.5 and 26 hr after intraperitoneal injection of the maximum non-toxic dose of sodium dichromate (10 mg/kg). While Cr(VI) at this dose did not significantly change hepatic, renal, or pulmonary GSH levels, there appeared to be an initial decrease of hepatic GSH followed by an increase to approximately 120% of control between 5 and 12.5 hr after Cr(VI) treatment. The increase in hepatic GSH levels was significant 5 hr after treatment with 20 mg/kg sodium dichromate, was manifested as an increase in both non-protein sulfhydryls and total glutathione, and was prevented by L-buthionine sulfoximine (BSO) pretreatment. In rats pretreated with 4.0 mmol/kg BSO to deplete GSH, subsequent treatment with Cr(VI) further reduced hepatic GSH levels 2 hr after Cr(VI) treatment and inhibited weight gain in the first 24 hr after treatment. Intraperitoneal injection of Cr(VI) did not inhibit hepatic glutathione reductase activity, even at toxic doses. Depletion of renal GSH to approximately 25% of control with BSO potentiated the acute nephrotoxicity of 30 mg/kg sodium dichromate as measured by serum urea nitrogen levels and relative kidney weight. However, GSH depletion with BSO did not appear to affect the incidence of glucosuria, haematuria, or lysozymuria over a range of Cr(VI) doses, nor did it affect renal uptake of Cr. Taken together, these data show that GSH protects against the acute nephrotoxicity of Cr(VI), although it is not clear whether GSH is directly involved in the intracellular metabolism of Cr(VI) at non-toxic doses.","Possible role of glutathione in chromium(VI) metabolism and toxicity in rats Abs: The effect of Cr(VI) on liver, kidney, and lung glutathione (GSH) levels and the effect of GSH depletion on Cr(VI)-induced nephrotoxicity were studied in male Sprague-Dawley rats (150-200 g). GSH levels, measured as nonprotein sulfhydryls, were determined between 0.5 and 26 hr after intraperitoneal injection of the maximum non-toxic dose of sodium dichromate (10 mg/kg). While Cr(VI) at this dose did not significantly change hepatic, renal, or pulmonary GSH levels, there appeared to be an initial decrease of hepatic GSH followed by an increase to approximately 120% of control between 5 and 12.5 hr after Cr(VI) treatment. The increase in hepatic GSH levels was significant 5 hr after treatment with 20 mg/kg sodium dichromate, was manifested as an increase in both non-protein sulfhydryls and total glutathione, and was prevented by L-buthionine sulfoximine (BSO) pretreatment. In rats pretreated with 4.0 mmol/kg BSO to deplete GSH, subsequent treatment with Cr(VI) further reduced hepatic GSH levels 2 hr after Cr(VI) treatment and inhibited weight gain in the first 24 hr after treatment. Intraperitoneal injection of Cr(VI) did not inhibit hepatic glutathione reductase activity, even at toxic doses. Depletion of renal GSH to approximately 25% of control with BSO potentiated the acute nephrotoxicity of 30 mg/kg sodium dichromate as measured by serum urea nitrogen levels and relative kidney weight. However, GSH depletion with BSO did not appear to affect the incidence of glucosuria, haematuria, or lysozymuria over a range of Cr(VI) doses, nor did it affect renal uptake of Cr. Taken together, these data show that GSH protects against the acute nephrotoxicity of Cr(VI), although it is not clear whether GSH is directly involved in the intracellular metabolism of Cr(VI) at non-toxic doses."
1235749,Kortenkamp et al. 1991,The reduction of chromate is a prerequisite of chromium binding to cell nuclei,"Isolated calf thymus nuclei bound a chromium(III) glutathione complex in a time-dependent manner. In contrast chromium(VI) (sodium chromate) did not bind. However, when chromate was incubated with the nuclei in the presence of glutathione, chromium adducts were detected. These observations indicate that the reduction of chromate, by a reducing agent such as glutathione, is a prerequisite for the generation of bonds between the metal and constituents of the cell nuclei in vitro. Chromium adducts with nuclei are probably one cause of DNA lesions and mutations.","The reduction of chromate is a prerequisite of chromium binding to cell nuclei Abs: Isolated calf thymus nuclei bound a chromium(III) glutathione complex in a time-dependent manner. In contrast chromium(VI) (sodium chromate) did not bind. However, when chromate was incubated with the nuclei in the presence of glutathione, chromium adducts were detected. These observations indicate that the reduction of chromate, by a reducing agent such as glutathione, is a prerequisite for the generation of bonds between the metal and constituents of the cell nuclei in vitro. Chromium adducts with nuclei are probably one cause of DNA lesions and mutations."
1235748,Sugiyama et al. 1991,Reduction of chromium(VI) in Chinese hamster V-79 cells,"The cellular reduction of chromate(VI) was studied by electron spin resonance spectrometry. Incubation of Chinese hamster V-79 cells with Na2CrO4 resulted in the formation of both chromium(V) and chromium(III) complex in a manner dependent on time (30 min-2 h) and concentration (50-500 microM). Following removal of extracellular chromate, the level of chromium(V) complex decreased quickly during the first hour but more slowly for the next hour, whereas the level of chromium(III) remained unchanged, indicating that chromium(III) is the ultimate ion of this metal in cells. Alkaline elution studies demonstrated that treatment of cells with Na2CrO4 induced DNA single-strand breaks that decreased quickly and DNA-protein crosslinks that persisted for 2 h after removal of this metal. These results suggest that the cellular levels of chromium(V) and chromium(III) may be associated with the formation of DNA damage induced by chromium (VI).","Reduction of chromium(VI) in Chinese hamster V-79 cells Abs: The cellular reduction of chromate(VI) was studied by electron spin resonance spectrometry. Incubation of Chinese hamster V-79 cells with Na2CrO4 resulted in the formation of both chromium(V) and chromium(III) complex in a manner dependent on time (30 min-2 h) and concentration (50-500 microM). Following removal of extracellular chromate, the level of chromium(V) complex decreased quickly during the first hour but more slowly for the next hour, whereas the level of chromium(III) remained unchanged, indicating that chromium(III) is the ultimate ion of this metal in cells. Alkaline elution studies demonstrated that treatment of cells with Na2CrO4 induced DNA single-strand breaks that decreased quickly and DNA-protein crosslinks that persisted for 2 h after removal of this metal. These results suggest that the cellular levels of chromium(V) and chromium(III) may be associated with the formation of DNA damage induced by chromium (VI)."
1235745,Snyder and  Valle 1991,Lymphocyte proliferation assays as potential biomarkers for toxicant exposures,"Recently there has been interest in developing assays that can be used as indicators (biomarkers) of exposure to toxic agents. We have been exploring the potential utility of three lymphocyte proliferation assays [the responses of B lymphocytes to the mitogen lipopolysaccharide (LPS), the responses of T lymphocytes to the mitogen concanavalin A (ConA), and the responses of T lymphocytes to antigenic stimuli in a mixed lymphocyte culture (MLC) assay] as biomarkers of toxicant exposure. Studies were initiated to assess the applicability and specificity of these assays and to investigate the mechanisms by which toxicants alter lymphocyte proliferation. All studies were performed using cells isolated from Fischer 344 rats. To assess applicability, mitogen assays were performed using in vitro exposures to eight different toxicants: hydroquinone, benzoquinone, Aroclor 1254, styrene oxide, and the salts of mercury, cadmium, chromate, and nickel. In vitro concentrations spanned five orders of magnitude (100 to 0.01 mg/l). At the lowest concentration tested, all eight compounds induced changes in at least one mitogen assay, indicating that these assays may be applicable to a wide range of toxicants. Variations of the ConA and MLC assays were used to test for specificity. In both assays, splenocytes taken from rats exposed in vivo to either chromate or to cadmium responded differently when the cells were cocultured with exogenously added chromate or cadmium ions, indicating that it may be possible to detect exposure to a specific toxicant by performing modified lymphocyte proliferation assays. In the mechanistic studies, splenocytes from cadmium and chromate-treated rats altered the ConA-induced proliferation of cocultured syngeneic cells. In addition, the antigenicity of splenocytes isolated from cadmium-treated rats was enhanced when these cells were used as stimulators for allogeneic splenocytes. The results of these studies indicate that lymphocyte proliferation assays may be useful for detecting exposure to a wide range of toxicants and that variations of these assays may be useful for implementing immunologically based tests for detecting exposures to specific chemicals.","Lymphocyte proliferation assays as potential biomarkers for toxicant exposures Abs: Recently there has been interest in developing assays that can be used as indicators (biomarkers) of exposure to toxic agents. We have been exploring the potential utility of three lymphocyte proliferation assays [the responses of B lymphocytes to the mitogen lipopolysaccharide (LPS), the responses of T lymphocytes to the mitogen concanavalin A (ConA), and the responses of T lymphocytes to antigenic stimuli in a mixed lymphocyte culture (MLC) assay] as biomarkers of toxicant exposure. Studies were initiated to assess the applicability and specificity of these assays and to investigate the mechanisms by which toxicants alter lymphocyte proliferation. All studies were performed using cells isolated from Fischer 344 rats. To assess applicability, mitogen assays were performed using in vitro exposures to eight different toxicants: hydroquinone, benzoquinone, Aroclor 1254, styrene oxide, and the salts of mercury, cadmium, chromate, and nickel. In vitro concentrations spanned five orders of magnitude (100 to 0.01 mg/l). At the lowest concentration tested, all eight compounds induced changes in at least one mitogen assay, indicating that these assays may be applicable to a wide range of toxicants. Variations of the ConA and MLC assays were used to test for specificity. In both assays, splenocytes taken from rats exposed in vivo to either chromate or to cadmium responded differently when the cells were cocultured with exogenously added chromate or cadmium ions, indicating that it may be possible to detect exposure to a specific toxicant by performing modified lymphocyte proliferation assays. In the mechanistic studies, splenocytes from cadmium and chromate-treated rats altered the ConA-induced proliferation of cocultured syngeneic cells. In addition, the antigenicity of splenocytes isolated from cadmium-treated rats was enhanced when these cells were used as stimulators for allogeneic splenocytes. The results of these studies indicate that lymphocyte proliferation assays may be useful for detecting exposure to a wide range of toxicants and that variations of these assays may be useful for implementing immunologically based tests for detecting exposures to specific chemicals."
1235744,Eriksen et al. 1991,Natural killer cell cytotoxicity to herpes simplex virus-1-infected cells is not altered by pregnancy,"There is evidence to suggest a decrease in natural killer cell cytotoxicity during pregnancy, but information regarding immune responsiveness to actual infection is limited. An in vitro study was undertaken to examine the effect of herpes simplex virus infection on natural killer cell cytotoxicity with peripheral blood mononuclear cells from pregnant (N = 8) and nonpregnant (N = 5) women. The peripheral blood mononuclear cells were separated by Ficoll-Hypaque centrifugation. Effector cells were incubated with live herpes simplex virus-1, ultraviolet-inactivated herpes simplex virus-1, or media alone for 18 hours at 37 degrees C. K562 target cells were used in a sodium chromate release assay with an effector-to-target cell ratio of 100:1. Baseline natural killer cell values (mean +/- SE) for pregnant patients (13.4% +/- 2.4%) and nonpregnant patients (19.8% +/- 3.7%) were similar. Natural killer cell cytotoxicity was significantly increased by incubation with live virus for both pregnant (37.5% +/- 6.2%) and nonpregnant subjects (49.8% +/- 7.6%). There was no difference in mean values between media and ultraviolet-inactivated herpes simplex virus-1-exposed samples for either group. Results suggest that (1) infection with live virus, but not viral antigen alone, can augment natural killer cell response in vitro and (2) natural killer cell response to herpes simplex virus-1 infection is not altered by pregnancy.","Natural killer cell cytotoxicity to herpes simplex virus-1-infected cells is not altered by pregnancy Abs: There is evidence to suggest a decrease in natural killer cell cytotoxicity during pregnancy, but information regarding immune responsiveness to actual infection is limited. An in vitro study was undertaken to examine the effect of herpes simplex virus infection on natural killer cell cytotoxicity with peripheral blood mononuclear cells from pregnant (N = 8) and nonpregnant (N = 5) women. The peripheral blood mononuclear cells were separated by Ficoll-Hypaque centrifugation. Effector cells were incubated with live herpes simplex virus-1, ultraviolet-inactivated herpes simplex virus-1, or media alone for 18 hours at 37 degrees C. K562 target cells were used in a sodium chromate release assay with an effector-to-target cell ratio of 100:1. Baseline natural killer cell values (mean +/- SE) for pregnant patients (13.4% +/- 2.4%) and nonpregnant patients (19.8% +/- 3.7%) were similar. Natural killer cell cytotoxicity was significantly increased by incubation with live virus for both pregnant (37.5% +/- 6.2%) and nonpregnant subjects (49.8% +/- 7.6%). There was no difference in mean values between media and ultraviolet-inactivated herpes simplex virus-1-exposed samples for either group. Results suggest that (1) infection with live virus, but not viral antigen alone, can augment natural killer cell response in vitro and (2) natural killer cell response to herpes simplex virus-1 infection is not altered by pregnancy."
1235742,Puri et al. 1991,Inter-laboratory ring trial of in vitro DNA repair tests using rat hepatocytes: further testing and conclusive remarks,"The results of the extension of a collaborative study for the detection of chemical-induced DNA damage in rat hepatocytes in vitro are presented in this report. Three coded compounds, i.e. 1,4-butanediol dimethanesulphonate, hydrazine sulphate and sodium dichromate, were tested for DNA repair synthesis by seven different laboratories, either using autoradiographic procedures or the liquid scintillation counting technique. Inter-laboratory standardization was intentionally not requested in order to investigate the validity of each study design under routine conditions. 1,4-Butanediol dimethanesulphonate was clearly positive in most laboratories; sodium dichromate was generally positive, while the results on hydrazine sulphate were contradictory.","Inter-laboratory ring trial of in vitro DNA repair tests using rat hepatocytes: further testing and conclusive remarks Abs: The results of the extension of a collaborative study for the detection of chemical-induced DNA damage in rat hepatocytes in vitro are presented in this report. Three coded compounds, i.e. 1,4-butanediol dimethanesulphonate, hydrazine sulphate and sodium dichromate, were tested for DNA repair synthesis by seven different laboratories, either using autoradiographic procedures or the liquid scintillation counting technique. Inter-laboratory standardization was intentionally not requested in order to investigate the validity of each study design under routine conditions. 1,4-Butanediol dimethanesulphonate was clearly positive in most laboratories; sodium dichromate was generally positive, while the results on hydrazine sulphate were contradictory."
1235740,Shi and  Dalal 1992,The role of superoxide radical in chromium (VI)-generated hydroxyl radical: the Cr(VI) Haber-Weiss cycle,"To understand the role of the superoxide (O-2) radical in chromate-related genotoxicity, we investigated whether Cr(VI) can catalyze the Haber-Weiss cycle in vitro: O-2 + Cr(VI)----Cr(V) + O2 Cr(V) + H2O2----Cr(VI) + .OH + OH-. ESR and spin trapping techniques were utilized to monitor the O-2 (produced using xanthine/xanthine oxidase), .OH, and Cr(V) species. Superoxide dismutase as well as catalase inhibited the .OH radical radical formation, attesting to the direct involvement of O-2 and H2O2 in the process. ESR measurements also provided direct evidence for the formation of Cr(V). Kinetic measurements were consistent with the role of Cr(V) and H2O2 as intermediates in .OH formation. These results indicate that in cellular media, especially during chromate phagocytosis, the O-2 radical can become a significant source of .OH radicals and hence a significant factor in the biochemical mechanism of cellular damage due to Cr(VI) exposure.","The role of superoxide radical in chromium (VI)-generated hydroxyl radical: the Cr(VI) Haber-Weiss cycle Abs: To understand the role of the superoxide (O-2) radical in chromate-related genotoxicity, we investigated whether Cr(VI) can catalyze the Haber-Weiss cycle in vitro: O-2 + Cr(VI)----Cr(V) + O2 Cr(V) + H2O2----Cr(VI) + .OH + OH-. ESR and spin trapping techniques were utilized to monitor the O-2 (produced using xanthine/xanthine oxidase), .OH, and Cr(V) species. Superoxide dismutase as well as catalase inhibited the .OH radical radical formation, attesting to the direct involvement of O-2 and H2O2 in the process. ESR measurements also provided direct evidence for the formation of Cr(V). Kinetic measurements were consistent with the role of Cr(V) and H2O2 as intermediates in .OH formation. These results indicate that in cellular media, especially during chromate phagocytosis, the O-2 radical can become a significant source of .OH radicals and hence a significant factor in the biochemical mechanism of cellular damage due to Cr(VI) exposure."
1235738,Na et al. 1992,The role of glutathione in the acute nephrotoxicity of sodium dichromate,"Ascorbate treatment 30 min prior to sodium dichromate (20 or 30 mg/kg, s.c.) shows higher potency than that of glutathione (GSH) in protecting against both the metabolic disturbance and nephrotoxicity induced by dichromate. However, ascorbate treatment after 2 h of dichromate intoxication had no effect on dichromate-induced blood urea nitrogen (BUN) elevation 3 days after intoxication. In contrast, dichromate-induced glucosuria, which reached maximum levels at 3 days after treatment, was significantly decreased by GSH or N-acetyl cysteine (NAC) treatment, even if its administration was after 24 h of dichromate intoxication. Pretreatment with GSH depletors such as diethyl maleate (DEM) and buthionine sulfoximine (BSO) had no effect on dichromate-induced nephrotoxicity. GSH levels in the liver and kidney were not affected at 3 h after dichromate treatment. However, dichromate significantly increased tissue GSH levels with a marked increase in liver per kidney GSH ratio at 24 h after treatment, if food was withheld subsequent to dichromate treatment, indicating that GSH biosynthesis resulted from the accelerated protein breakdown. These results suggest that GSH-mediated dichromate reduction is not a kinetically favorable pathway in vivo; however, GSH plays an important role in protection against dichromate-induced nephrotoxicity. In addition, the cellular metabolism of dichromate in the early period after treatment is important in the pathogenesis of its nephrotoxicity.","The role of glutathione in the acute nephrotoxicity of sodium dichromate Abs: Ascorbate treatment 30 min prior to sodium dichromate (20 or 30 mg/kg, s.c.) shows higher potency than that of glutathione (GSH) in protecting against both the metabolic disturbance and nephrotoxicity induced by dichromate. However, ascorbate treatment after 2 h of dichromate intoxication had no effect on dichromate-induced blood urea nitrogen (BUN) elevation 3 days after intoxication. In contrast, dichromate-induced glucosuria, which reached maximum levels at 3 days after treatment, was significantly decreased by GSH or N-acetyl cysteine (NAC) treatment, even if its administration was after 24 h of dichromate intoxication. Pretreatment with GSH depletors such as diethyl maleate (DEM) and buthionine sulfoximine (BSO) had no effect on dichromate-induced nephrotoxicity. GSH levels in the liver and kidney were not affected at 3 h after dichromate treatment. However, dichromate significantly increased tissue GSH levels with a marked increase in liver per kidney GSH ratio at 24 h after treatment, if food was withheld subsequent to dichromate treatment, indicating that GSH biosynthesis resulted from the accelerated protein breakdown. These results suggest that GSH-mediated dichromate reduction is not a kinetically favorable pathway in vivo; however, GSH plays an important role in protection against dichromate-induced nephrotoxicity. In addition, the cellular metabolism of dichromate in the early period after treatment is important in the pathogenesis of its nephrotoxicity."
1235737,Orfila et al. 1992,Evidence for intrarenal kallikrein storage during chromate-induced acute renal failure in rat,"During the course of chromate-induced acute renal failure (ARF), urinary kallikrein excretion (UKE), a serine protease of distal tubule origin in the normal animal was decreased but tissue kallikrein concentration (TK) was increased, suggesting intracellular accumulation. Severe morphological lesions were observed in proximal tubular cells which showed brush border damage, numerous vesicles, necrosis and liquefaction of cytoplasmic material. Less marked changes were also present in distal tubules: large apical vacuoles and swollen mitochondria. Compared to normal rats, using the peroxidase-anti-peroxidase (PAP) method for light microscopy, greater kallikrein immunoreactivity was detected along the apical pole in distal tubules, on the membrane and in the cytoplasm as well as in the glomerulus. By immunoelectron microscopy, kallikrein was found in the connecting apical area, along the luminal, basolateral and basement membranes, in some vesicles, in Golgi apparatus and on ribosomes bound to endoplasmic reticulum. In the glomerulus, kallikrein was observed along the luminal surface of endothelial cell. After 14 days a progressive recovery of renal function, tissue morphology and UKE towards control values was observed. The presence of immunoreactive kallikrein in the glomerulus observed only during ARF confirmed the previous demonstration of kallikrein mRNA in the glomerulus. The cellular accumulation results more likely from a dysfunction of a general secretory mechanism due to cell membrane alteration than from a specific inhibition of kallikrein production and secretion.","Evidence for intrarenal kallikrein storage during chromate-induced acute renal failure in rat Abs: During the course of chromate-induced acute renal failure (ARF), urinary kallikrein excretion (UKE), a serine protease of distal tubule origin in the normal animal was decreased but tissue kallikrein concentration (TK) was increased, suggesting intracellular accumulation. Severe morphological lesions were observed in proximal tubular cells which showed brush border damage, numerous vesicles, necrosis and liquefaction of cytoplasmic material. Less marked changes were also present in distal tubules: large apical vacuoles and swollen mitochondria. Compared to normal rats, using the peroxidase-anti-peroxidase (PAP) method for light microscopy, greater kallikrein immunoreactivity was detected along the apical pole in distal tubules, on the membrane and in the cytoplasm as well as in the glomerulus. By immunoelectron microscopy, kallikrein was found in the connecting apical area, along the luminal, basolateral and basement membranes, in some vesicles, in Golgi apparatus and on ribosomes bound to endoplasmic reticulum. In the glomerulus, kallikrein was observed along the luminal surface of endothelial cell. After 14 days a progressive recovery of renal function, tissue morphology and UKE towards control values was observed. The presence of immunoreactive kallikrein in the glomerulus observed only during ARF confirmed the previous demonstration of kallikrein mRNA in the glomerulus. The cellular accumulation results more likely from a dysfunction of a general secretory mechanism due to cell membrane alteration than from a specific inhibition of kallikrein production and secretion."
1235736,Pons et al. 1992,Leukotriene D4 participates in colonic transit disturbances induced by intracolonic administration of trinitrobenzene sulfonic acid in rats,"The effects of colonic inflammation induced by trinitrobenzene sulfonic acid and influence of previous treatment with specific antagonists of inflammatory mediators (platelet-activating factor, leukotrienes, prostaglandins, and thromboxanes) on colonic transit were examined in conscious rats which were permanently fitted with an intracolonic catheter inserted into the proximal colon. Colonic inflammation was induced by intracolonic administration of trinitrobenzene acid (80 mg/kg) in 50% ethanol. Colonic transit time was evaluated by intracolonic administration of a radiolabeled marker [( 51Cr]sodium chromate) and collection of the feces per hour on a conveyor belt. Excretion of the marker was then plotted vs. time, permitting calculations of the times elapsed to recover 25%, 50%, and 75% of the marker injected (T25, T50, and T75, respectively). In control (saline) animals, excretion of the marker described a regular sigmoid curve with 50% of the marker recovered at 6.92 +/- 0.40 hours after intracolonic administration (T25 = 6.4 +/- 0.43 hours; T75 = 7.49 +/- 0.39 hours). Ethanol (vehicle), 50%, did not modify the profile of marker recovery. On the contrary, single intracolonic administration of trinitrobenzene sulfonic acid/ethanol induced a biphasic response consisting of an early pool of radiolabeled feces (T25 = 4.03 +/- 0.55 hours) with a delayed total one (T50 = 11.74 +/- 0.83 hours; T75 = 13.70 +/- 0.49 hours). Antagonists of the leukotriene pathway, i.e., MK = 886, a lipoxygenase inhibitor, and SKF 104,353 and SR 2640, two different leukotriene D4 receptor antagonists, blocked the effects of trinitrobenzene sulfonic acid on colonic transit time and restored a control profile of radiolabeled marker excretion. In contrast, indomethacin, a cyclooxygenase inhibitor, and SC 19220, a specific prostaglandin E2 receptor antagonist, were inefficient in blocking the effects of trinitrobenzene sulfonic acid on colonic transit time. Specific thromboxane A2 receptor antagonists, KT1-32 and GR 32191B, did not show any improvement in colonic transit after trinitrobenzene sulfonic acid administration. Previous injection of the specific platelet-activating factor receptor antagonists, BN 52021 or BN 50730, was also unable to restore a normal marker excretion profile after administration of trinitrobenzene sulfonic acid. It is concluded that the alterations of colonic transit immediately observed after intracolonic trinitrobenzene sulfonic acid administration are mediated through the release of leukotriene D4. In contrast, platelet-activating factor, prostaglandins, and thromboxanes are not involved in the mediation of these transit disturbances.","Leukotriene D4 participates in colonic transit disturbances induced by intracolonic administration of trinitrobenzene sulfonic acid in rats Abs: The effects of colonic inflammation induced by trinitrobenzene sulfonic acid and influence of previous treatment with specific antagonists of inflammatory mediators (platelet-activating factor, leukotrienes, prostaglandins, and thromboxanes) on colonic transit were examined in conscious rats which were permanently fitted with an intracolonic catheter inserted into the proximal colon. Colonic inflammation was induced by intracolonic administration of trinitrobenzene acid (80 mg/kg) in 50% ethanol. Colonic transit time was evaluated by intracolonic administration of a radiolabeled marker [( 51Cr]sodium chromate) and collection of the feces per hour on a conveyor belt. Excretion of the marker was then plotted vs. time, permitting calculations of the times elapsed to recover 25%, 50%, and 75% of the marker injected (T25, T50, and T75, respectively). In control (saline) animals, excretion of the marker described a regular sigmoid curve with 50% of the marker recovered at 6.92 +/- 0.40 hours after intracolonic administration (T25 = 6.4 +/- 0.43 hours; T75 = 7.49 +/- 0.39 hours). Ethanol (vehicle), 50%, did not modify the profile of marker recovery. On the contrary, single intracolonic administration of trinitrobenzene sulfonic acid/ethanol induced a biphasic response consisting of an early pool of radiolabeled feces (T25 = 4.03 +/- 0.55 hours) with a delayed total one (T50 = 11.74 +/- 0.83 hours; T75 = 13.70 +/- 0.49 hours). Antagonists of the leukotriene pathway, i.e., MK = 886, a lipoxygenase inhibitor, and SKF 104,353 and SR 2640, two different leukotriene D4 receptor antagonists, blocked the effects of trinitrobenzene sulfonic acid on colonic transit time and restored a control profile of radiolabeled marker excretion. In contrast, indomethacin, a cyclooxygenase inhibitor, and SC 19220, a specific prostaglandin E2 receptor antagonist, were inefficient in blocking the effects of trinitrobenzene sulfonic acid on colonic transit time. Specific thromboxane A2 receptor antagonists, KT1-32 and GR 32191B, did not show any improvement in colonic transit after trinitrobenzene sulfonic acid administration. Previous injection of the specific platelet-activating factor receptor antagonists, BN 52021 or BN 50730, was also unable to restore a normal marker excretion profile after administration of trinitrobenzene sulfonic acid. It is concluded that the alterations of colonic transit immediately observed after intracolonic trinitrobenzene sulfonic acid administration are mediated through the release of leukotriene D4. In contrast, platelet-activating factor, prostaglandins, and thromboxanes are not involved in the mediation of these transit disturbances."
1235735,Morrissey et al. 1992,Chromium-51 labeling of sheep red blood cells,"The failure of sheep red blood cells (RBCs) labeled with Chromium-51 (Cr-51) using the ascorbic acid technique to act as a suitable intravascular marker of blood volume in a septic sheep model prompted us to investigate the technique of radiolabeling sheep erythrocytes with this isotope. Consequently, we studied thirteen sheep in which the labeling efficiency of Cr-51 as sodium chromate and hemoglobin typing was determined for each animal. Mean Cr-51 labeling efficiency of sheep RBCs was 67.5% (n = 13). Although 5 of the 13 sheep were discovered to have two types of hemoglobin (Hb) as determined by electrophoresis, overall labeling efficiency of sheep RBCs was determined to be independent of the type of hemoglobin present. However, when two types of Hb were present (Hb-A and Hb-B), Cr-51 had a higher affinity for Hb-B (80%) than Hb-A (20%) even though both Hb types are present in similar proportions (Hb-A = 53%, Hb-B = 46%). The results of this study indicate that sheep RBCs express a lower labeling efficiency for Cr-51 than do human RBCs and that Cr-51 has a higher affinity for Hb-B than for Hb-A when both hemoglobin types are present. This difference is noteworthy when interpreting Cr-51 RBC data in experimental sheep models. Furthermore, caution should be exercised when extrapolating established human protocols to animal models.","Chromium-51 labeling of sheep red blood cells Abs: The failure of sheep red blood cells (RBCs) labeled with Chromium-51 (Cr-51) using the ascorbic acid technique to act as a suitable intravascular marker of blood volume in a septic sheep model prompted us to investigate the technique of radiolabeling sheep erythrocytes with this isotope. Consequently, we studied thirteen sheep in which the labeling efficiency of Cr-51 as sodium chromate and hemoglobin typing was determined for each animal. Mean Cr-51 labeling efficiency of sheep RBCs was 67.5% (n = 13). Although 5 of the 13 sheep were discovered to have two types of hemoglobin (Hb) as determined by electrophoresis, overall labeling efficiency of sheep RBCs was determined to be independent of the type of hemoglobin present. However, when two types of Hb were present (Hb-A and Hb-B), Cr-51 had a higher affinity for Hb-B (80%) than Hb-A (20%) even though both Hb types are present in similar proportions (Hb-A = 53%, Hb-B = 46%). The results of this study indicate that sheep RBCs express a lower labeling efficiency for Cr-51 than do human RBCs and that Cr-51 has a higher affinity for Hb-B than for Hb-A when both hemoglobin types are present. This difference is noteworthy when interpreting Cr-51 RBC data in experimental sheep models. Furthermore, caution should be exercised when extrapolating established human protocols to animal models."
1235734,Tavéra et al. 1992,Cystatin C secretion by rat glomerular mesangial cells: autocrine loop for in vitro growth-promoting activity,"Cystatin C, the major inhibitor of the cysteine proteinases found in human and rat body fluids, is particularly abundant in seminal plasma and cerebrospinal fluid. In a precedent report, we have evidenced noteworthy levels of cystatin C in rat kidney cortex. In the present study, we show that rat mesangial glomerular cells produce cystatin C. Immunoprecipitation of extracts of metabolically labeled cells and culture media showed that the synthesized cystatin C is a 15.5 +/- 0.5 kDa protein. The protein was released into the culture supernatant (1.6 +/- 0.26 micrograms/10(6) cells/24 h). Urinary rat cystatin C and PPPR synthetic peptide (5-8 N-terminal sequence of rat cystatin C) increased mesangial cell proliferation. Affinity chromatography on Ultrogel-avidin-biotin-PPPR of extracts of metabolically labeled cells indicate the existence of a PPPR binding protein of 46 kDa. The results described in this work suggest, for glomerular rat mesangial cells in vitro, an autocrine regulation of proliferation by cystatin C.","Cystatin C secretion by rat glomerular mesangial cells: autocrine loop for in vitro growth-promoting activity Abs: Cystatin C, the major inhibitor of the cysteine proteinases found in human and rat body fluids, is particularly abundant in seminal plasma and cerebrospinal fluid. In a precedent report, we have evidenced noteworthy levels of cystatin C in rat kidney cortex. In the present study, we show that rat mesangial glomerular cells produce cystatin C. Immunoprecipitation of extracts of metabolically labeled cells and culture media showed that the synthesized cystatin C is a 15.5 +/- 0.5 kDa protein. The protein was released into the culture supernatant (1.6 +/- 0.26 micrograms/10(6) cells/24 h). Urinary rat cystatin C and PPPR synthetic peptide (5-8 N-terminal sequence of rat cystatin C) increased mesangial cell proliferation. Affinity chromatography on Ultrogel-avidin-biotin-PPPR of extracts of metabolically labeled cells indicate the existence of a PPPR binding protein of 46 kDa. The results described in this work suggest, for glomerular rat mesangial cells in vitro, an autocrine regulation of proliferation by cystatin C."
1235732,Lefebvre and  Pézerat 1992,Production of activated species of oxygen during the chromate(VI)-ascorbate reaction: implication in carcinogenesis,"The reaction of chromate and ascorbate in a 1:1 molar ratio at pH 7.4 and 37 degrees C produces a Cr(V) signal observable by EPR at g = 1.980. When this reaction is carried out in aerated media and in the presence of formate, carboxylate radicals (COO.-) can be trapped as DMPO-COO.- spin adducts (DMPO, 5,5-dimethyl-1-pyrroline N-oxide). The use of a known complexant of Cr(V), 2-ethyl-2-hydroxybutyric acid, produces a different Cr(V) signal at g = 1.978 and a decrease of the DMPO-COO.- signal. Hydroxyl radicals are not detected in the media. The oxidizing behavior is suggested to be produced by activation of molecular oxygen present in the reaction mixture.","Production of activated species of oxygen during the chromate(VI)-ascorbate reaction: implication in carcinogenesis Abs: The reaction of chromate and ascorbate in a 1:1 molar ratio at pH 7.4 and 37 degrees C produces a Cr(V) signal observable by EPR at g = 1.980. When this reaction is carried out in aerated media and in the presence of formate, carboxylate radicals (COO.-) can be trapped as DMPO-COO.- spin adducts (DMPO, 5,5-dimethyl-1-pyrroline N-oxide). The use of a known complexant of Cr(V), 2-ethyl-2-hydroxybutyric acid, produces a different Cr(V) signal at g = 1.978 and a decrease of the DMPO-COO.- signal. Hydroxyl radicals are not detected in the media. The oxidizing behavior is suggested to be produced by activation of molecular oxygen present in the reaction mixture."
1235730,Liebross and  Wetterhahn 1992,In vivo formation of chromium(V) in chick embryo liver and red blood cells,"In order to understand the possible role of reactive intermediates in the formation of tissue-specific DNA damage by chromium(VI), electron paramagnetic resonance spectroscopy was used to study the in vivo formation of chromium(V) in the liver and red blood cells of 14 day chick embryos following treatment with chromium(VI). In vivo administration of sodium dichromate onto the inner shell membrane of 14 day chick embryos resulted in the formation of a persistent chromium(V) species in liver cells (g = 1.987). The intensity of the chromium(V) signal in liver cells plateaued at 70 min and persisted for 240 min after treatment with chromium(VI). The dependence of chromium(V) formation on the dose of sodium dichromate administered to the embryo was clearly different in liver versus red blood cells. Chromium(V) was detected in red blood cells only at high doses of sodium dichromate (0.50-0.60 mmol/kg), whereas chromium(V) was undetectable in red blood cells at lower doses of sodium dichromate (0.10-0.30 mmol/kg) which produced clear evidence for chromium(V) in liver. Uptake studies showed that total chromium levels in red blood cells were 10-fold greater than in liver cells, and that up to 10% of the total chromium existed as chromium(V) in liver and red blood cells in vivo. Depletion of glutathione by pretreatment of embryos with L-buthionine-S,R-sulfoximine (BSO) for 24 h prior to treatment with a high dose of sodium dichromate (0.60 mmol/kg) caused both a decrease in the levels of chromium(V) species produced and a decrease of chromium uptake into red blood cells 50 min after treatment. At this high dose of chromium(VI), BSO pre-treatment had no effect on the level of the chromium(V) or on chromium uptake into liver cells after a 70 min incubation period. Thus, the concentration of chromium(V) inside the cell correlated with the levels of chromium taken up into the cell. Chromium(V) may be the form of chromium which is responsible for induction of DNA damage following in vivo administration of sodium dichromate.","In vivo formation of chromium(V) in chick embryo liver and red blood cells Abs: In order to understand the possible role of reactive intermediates in the formation of tissue-specific DNA damage by chromium(VI), electron paramagnetic resonance spectroscopy was used to study the in vivo formation of chromium(V) in the liver and red blood cells of 14 day chick embryos following treatment with chromium(VI). In vivo administration of sodium dichromate onto the inner shell membrane of 14 day chick embryos resulted in the formation of a persistent chromium(V) species in liver cells (g = 1.987). The intensity of the chromium(V) signal in liver cells plateaued at 70 min and persisted for 240 min after treatment with chromium(VI). The dependence of chromium(V) formation on the dose of sodium dichromate administered to the embryo was clearly different in liver versus red blood cells. Chromium(V) was detected in red blood cells only at high doses of sodium dichromate (0.50-0.60 mmol/kg), whereas chromium(V) was undetectable in red blood cells at lower doses of sodium dichromate (0.10-0.30 mmol/kg) which produced clear evidence for chromium(V) in liver. Uptake studies showed that total chromium levels in red blood cells were 10-fold greater than in liver cells, and that up to 10% of the total chromium existed as chromium(V) in liver and red blood cells in vivo. Depletion of glutathione by pretreatment of embryos with L-buthionine-S,R-sulfoximine (BSO) for 24 h prior to treatment with a high dose of sodium dichromate (0.60 mmol/kg) caused both a decrease in the levels of chromium(V) species produced and a decrease of chromium uptake into red blood cells 50 min after treatment. At this high dose of chromium(VI), BSO pre-treatment had no effect on the level of the chromium(V) or on chromium uptake into liver cells after a 70 min incubation period. Thus, the concentration of chromium(V) inside the cell correlated with the levels of chromium taken up into the cell. Chromium(V) may be the form of chromium which is responsible for induction of DNA damage following in vivo administration of sodium dichromate."
1235728,Stark et al. 1992,Detection of enhanced neutrophil adhesion to parainfluenza-infected airway epithelial cells using a modified myeloperoxidase assay in a microtiter format,"Despite growing evidence that respiratory virus infections precipitate episodes of airway obstruction and airway hyper-responsiveness in young children and in asthma, little information is available on the mechanisms by which virus infections alter the airway physiology. Airway inflammatory changes (including influx of inflammatory cells such as neutrophils) have been described during episodes of airway hyper-responsiveness in both animal models and human subjects. Neutrophil damage to several cell types has been shown to require adhesion as a primary step. In order to examine the potential interactions between virus-infected airway epithelial cells and neutrophils, we have studied the ability of neutrophils to adhere to virus-infected airway epithelial cell cultures. Neutrophil adherence was determined indirectly, using myeloperoxidase as a marker for adherent neutrophils in an assay system described here. Airway epithelial cell cultures (both primary human tracheal epithelial cells, and two permanent cell lines, A549 and BEAS-2B) were grown in 96-well tissue culture plates and infected with human parainfluenza virus type 2. Infected airway epithelial cell cultures supported significantly enhanced levels of neutrophil adherence (up to 50-75% of neutrophils added to the wells) compared to uninfected control cultures. Moreover, this adherence occurred in a virus dose-dependent fashion, with increasing levels of adherence noted at increasing viral multiplicities of infection. The assay system described allows the detection of small numbers of adherent neutrophils (as few as 1000 neutrophils) in a 96-well format.","Detection of enhanced neutrophil adhesion to parainfluenza-infected airway epithelial cells using a modified myeloperoxidase assay in a microtiter format Abs: Despite growing evidence that respiratory virus infections precipitate episodes of airway obstruction and airway hyper-responsiveness in young children and in asthma, little information is available on the mechanisms by which virus infections alter the airway physiology. Airway inflammatory changes (including influx of inflammatory cells such as neutrophils) have been described during episodes of airway hyper-responsiveness in both animal models and human subjects. Neutrophil damage to several cell types has been shown to require adhesion as a primary step. In order to examine the potential interactions between virus-infected airway epithelial cells and neutrophils, we have studied the ability of neutrophils to adhere to virus-infected airway epithelial cell cultures. Neutrophil adherence was determined indirectly, using myeloperoxidase as a marker for adherent neutrophils in an assay system described here. Airway epithelial cell cultures (both primary human tracheal epithelial cells, and two permanent cell lines, A549 and BEAS-2B) were grown in 96-well tissue culture plates and infected with human parainfluenza virus type 2. Infected airway epithelial cell cultures supported significantly enhanced levels of neutrophil adherence (up to 50-75% of neutrophils added to the wells) compared to uninfected control cultures. Moreover, this adherence occurred in a virus dose-dependent fashion, with increasing levels of adherence noted at increasing viral multiplicities of infection. The assay system described allows the detection of small numbers of adherent neutrophils (as few as 1000 neutrophils) in a 96-well format."
1235727,Sugiyama et al. 1992,Potentiation of sodium chromate(VI)-induced chromosomal aberrations and mutation by vitamin B2 in Chinese hamster V79 cells,"The effect of vitamin B2, which is capable of reducing chromium(VI) to chromium(V), on chromosomal aberrations and mutation caused by Na2CrO4 was investigated in Chinese hamster V79 cells. Pretreatment with 200 microM vitamin B2 (riboflavin) for 24 h prior to exposure to Na2CrO4 (2.5-5 microM) resulted in an increase of metal-induced chromosomal aberrations and mutation at the HGPRT locus. These and other previous studies suggest that vitamin B2 enhances the clastogenic and mutagenic action of chromate compounds, through its ability to directly reduce chromium(VI) in cells.","Potentiation of sodium chromate(VI)-induced chromosomal aberrations and mutation by vitamin B2 in Chinese hamster V79 cells Abs: The effect of vitamin B2, which is capable of reducing chromium(VI) to chromium(V), on chromosomal aberrations and mutation caused by Na2CrO4 was investigated in Chinese hamster V79 cells. Pretreatment with 200 microM vitamin B2 (riboflavin) for 24 h prior to exposure to Na2CrO4 (2.5-5 microM) resulted in an increase of metal-induced chromosomal aberrations and mutation at the HGPRT locus. These and other previous studies suggest that vitamin B2 enhances the clastogenic and mutagenic action of chromate compounds, through its ability to directly reduce chromium(VI) in cells."
1235726,Rani and  Kumar 1992,"Transformation of non-tumorigenic osteoblast-like human osteosarcoma cells by hexavalent chromates: alteration of morphology, induction of anchorage-independence and proteolytic function","Soluble chromium (VI) compounds either alone or in combination with 3-methylcholanthrene (MC) were used to transform non-tumorigenic osteoblast-like human osteosarcoma cells (HOS TE85). The Cr(VI) compounds were highly toxic to these cells with LC50 values in the range of approximately 0.5-1.0 microM. Continuous passaging of the treated cells resulted in sustained increase in anchorage-independent (AI) colony formation. Treatment with Cr(VI) and MC resulted in substantial increase in AI growth. At the XVth passage, a number of individual AI colonies were expanded in culture and used for further studies. The cells are refractory in appearance and grow as 'nests' rather than as monolayers. The cell lines have relatively high plating efficiency (PE) in soft agar and respond to promotional effect of phorbol-12-myristate-13-acetate by an increase in PE and in the size and number of AI colonies. While the isolated cells are not tumorigenic when tested in athymic nude mice, most of the lines possess higher levels of plasminogen activator (PA) activity, considered as one of the markers of transformation. This is also reflected in the increase in the steady state level of urokinase type PA mRNA. These results show that Cr(VI) compounds are capable of promoting human cells to an altered phenotype characteristic of a stage in the carcinogenesis cascade.","Transformation of non-tumorigenic osteoblast-like human osteosarcoma cells by hexavalent chromates: alteration of morphology, induction of anchorage-independence and proteolytic function Abs: Soluble chromium (VI) compounds either alone or in combination with 3-methylcholanthrene (MC) were used to transform non-tumorigenic osteoblast-like human osteosarcoma cells (HOS TE85). The Cr(VI) compounds were highly toxic to these cells with LC50 values in the range of approximately 0.5-1.0 microM. Continuous passaging of the treated cells resulted in sustained increase in anchorage-independent (AI) colony formation. Treatment with Cr(VI) and MC resulted in substantial increase in AI growth. At the XVth passage, a number of individual AI colonies were expanded in culture and used for further studies. The cells are refractory in appearance and grow as 'nests' rather than as monolayers. The cell lines have relatively high plating efficiency (PE) in soft agar and respond to promotional effect of phorbol-12-myristate-13-acetate by an increase in PE and in the size and number of AI colonies. While the isolated cells are not tumorigenic when tested in athymic nude mice, most of the lines possess higher levels of plasminogen activator (PA) activity, considered as one of the markers of transformation. This is also reflected in the increase in the steady state level of urokinase type PA mRNA. These results show that Cr(VI) compounds are capable of promoting human cells to an altered phenotype characteristic of a stage in the carcinogenesis cascade."
1235722,Bompart et al. 1993,Increase in renal and urinary low and high molecular weight kininogens during chromate-induced acute renal failure in the rat: evidence for renal kininogen production,"In the present study, we investigated the plasma, urinary and intrarenal concentrations of low and high molecular weight kininogens during sodium chromate (25 mg/kg body weight)-induced acute renal failure (ARF) in the rat. Urinary kininogen underwent a transient increase with a maximum on day 7 (78 +/- 22 versus 4.2 +/- 1.6 ng bradykinin/mg creatinine) whereas plasma kininogen did not and glomerular filtration rate decreased (92 +/- 8 versus 895 +/- 70 microliters/min). The tissue level of kininogen was enhanced both in the cortex (1,319 +/- 123 versus 86 +/- 8 pg bradykinin Eq/mg protein) and in the medulla (1,673 +/- 138 versus 44 +/- 9 pg bradykinin Eq/mg protein) but more in the medulla (36 +/- 4- versus 15 +/- 3-fold). As plasma kininogen level was unchanged and glomerular filtration rate decreased, the increase in both renal concentration and urinary excretion of kininogen probably reflects stimulated renal production of kininogen in this model of ARF. Whether the evoked renal production of kininogen results from a local inflammatory response only or may subserve another physiological purpose remains to be elucidated.","Increase in renal and urinary low and high molecular weight kininogens during chromate-induced acute renal failure in the rat: evidence for renal kininogen production Abs: In the present study, we investigated the plasma, urinary and intrarenal concentrations of low and high molecular weight kininogens during sodium chromate (25 mg/kg body weight)-induced acute renal failure (ARF) in the rat. Urinary kininogen underwent a transient increase with a maximum on day 7 (78 +/- 22 versus 4.2 +/- 1.6 ng bradykinin/mg creatinine) whereas plasma kininogen did not and glomerular filtration rate decreased (92 +/- 8 versus 895 +/- 70 microliters/min). The tissue level of kininogen was enhanced both in the cortex (1,319 +/- 123 versus 86 +/- 8 pg bradykinin Eq/mg protein) and in the medulla (1,673 +/- 138 versus 44 +/- 9 pg bradykinin Eq/mg protein) but more in the medulla (36 +/- 4- versus 15 +/- 3-fold). As plasma kininogen level was unchanged and glomerular filtration rate decreased, the increase in both renal concentration and urinary excretion of kininogen probably reflects stimulated renal production of kininogen in this model of ARF. Whether the evoked renal production of kininogen results from a local inflammatory response only or may subserve another physiological purpose remains to be elucidated."
1235719,Sugiyama et al. 1993,DNA single-strand breaks and cytotoxicity induced by sodium chromate(VI) in hydrogen peroxide-resistant cell lines,"Hydrogen peroxide-resistant Chinese hamster ovary (CHOR) cells were developed by exposing parental (CHO(P)) cells to sequential increases in H2O2 concentration. Cytotoxicity as well as DNA single-strand breaks induced by Na2CrO4 were then compared in CHOR and CHO(P) cell lines. Using the colony-forming assay, it was found that the cytotoxicity caused by Na2CrO4 did not differ in the parent and resistant cells. However, alkaline elution studies showed that the production of DNA single-strand breaks in CHOR cells treated with Na2CrO4 was reduced by about 50% as compared with that in CHO(P) cells. Similarly, electron spin resonance (ESR) studies revealed that the level of chromium(V) in CHOR cells during treatment with Na2CrO4 was about 50% that in CHO(P) cells. CHOR cells were also found to be cross-resistant to the cytotoxicity and DNA breaks caused by other toxic metals such as CdCl2 and HgCl2. Catalase activity in resistant cells was 2-fold and the cellular content of glutathione was 3-fold that in parental cells. However, no obvious differences were seen in superoxide dismutase and glutathione reductase activity, although the contents of ascorbic acid or alpha-tocopherol were slightly decreased in CHOR cells, suggesting that the resistance in CHOR cells may be associated with the increase in both catalase activity and glutathione contents in cells. These results indicate that chromate-induced DNA breaks appear to be mediated by a different mechanism than that for the cytotoxicity of this metal, and also suggest that the formation of active oxygen species and/or chromium(V) during reduction of chromium(VI) inside cells might be associated with the induction of the DNA strand breaks caused by the metal.","DNA single-strand breaks and cytotoxicity induced by sodium chromate(VI) in hydrogen peroxide-resistant cell lines Abs: Hydrogen peroxide-resistant Chinese hamster ovary (CHOR) cells were developed by exposing parental (CHO(P)) cells to sequential increases in H2O2 concentration. Cytotoxicity as well as DNA single-strand breaks induced by Na2CrO4 were then compared in CHOR and CHO(P) cell lines. Using the colony-forming assay, it was found that the cytotoxicity caused by Na2CrO4 did not differ in the parent and resistant cells. However, alkaline elution studies showed that the production of DNA single-strand breaks in CHOR cells treated with Na2CrO4 was reduced by about 50% as compared with that in CHO(P) cells. Similarly, electron spin resonance (ESR) studies revealed that the level of chromium(V) in CHOR cells during treatment with Na2CrO4 was about 50% that in CHO(P) cells. CHOR cells were also found to be cross-resistant to the cytotoxicity and DNA breaks caused by other toxic metals such as CdCl2 and HgCl2. Catalase activity in resistant cells was 2-fold and the cellular content of glutathione was 3-fold that in parental cells. However, no obvious differences were seen in superoxide dismutase and glutathione reductase activity, although the contents of ascorbic acid or alpha-tocopherol were slightly decreased in CHOR cells, suggesting that the resistance in CHOR cells may be associated with the increase in both catalase activity and glutathione contents in cells. These results indicate that chromate-induced DNA breaks appear to be mediated by a different mechanism than that for the cytotoxicity of this metal, and also suggest that the formation of active oxygen species and/or chromium(V) during reduction of chromium(VI) inside cells might be associated with the induction of the DNA strand breaks caused by the metal."
1235718,Kyan-Aung et al. 1993,The inhibitory effect of tenidap on leukocyte-endothelial cell adhesion,"<strong>OBJECTIVE: </strong>Adhesion of neutrophils to vascular endothelial cells (EC) and neutrophil chemotaxis are essential processes which enable neutrophils to infiltrate the tissues. They represent potentially important targets for therapeutic intervention in inflammatory diseases. This study was conducted to test the effect of tenidap sodium on neutrophil adhesion and chemotaxis.<br /><br /><strong>METHODS: </strong>Adhesion of 51Cr sodium chromate labelled neutrophils to umbilical vein EC monolayers was assayed in 96-well microtiter plates. Neutrophil chemotaxis was measured in Boyden microchemotaxis chambers.<br /><br /><strong>RESULTS: </strong>Tenidap sodium caused a dose related inhibition of neutrophil adhesion to EC, with 50 microM tenidap resulting in 51.8 +/- 4.0% (mean +/- SEM) inhibition of unstimulated adhesion and 46.1 +/- 2.6% inhibition of formyl-methionyl-leucyl-phenylalanine (FMLP) stimulated adhesion. A marked reduction in neutrophil chemotaxis in response to FMLP was also observed, with 50 microM and 100 microM tenidap leading to 83.4 +/- 8.5% and 92.1 +/- 8.5% (mean +/- SEM) inhibition respectively. The effect of tenidap on neutrophil adhesion to EC was not seen when neutrophils were preincubated with tenidap and then washed before adding to EC monolayers, suggesting an action upon surface molecules or in the cell membrane. Aspirin, indomethacin and phenylbutazone did not inhibit leukocyte adhesion, indicating that this action of tenidap may not be a consequence of inhibition of cyclooxygenase. The potency of tenidap was reduced by inclusion of serum or plasma in the culture medium, presumably due to protein binding.<br /><br /><strong>CONCLUSION: </strong>It is possible that inhibition of leukocyte-EC adhesion by tenidap sodium may contribute to the antiinflammatory effects of the drug.","The inhibitory effect of tenidap on leukocyte-endothelial cell adhesion Abs: <strong>OBJECTIVE: </strong>Adhesion of neutrophils to vascular endothelial cells (EC) and neutrophil chemotaxis are essential processes which enable neutrophils to infiltrate the tissues. They represent potentially important targets for therapeutic intervention in inflammatory diseases. This study was conducted to test the effect of tenidap sodium on neutrophil adhesion and chemotaxis.<br /><br /><strong>METHODS: </strong>Adhesion of 51Cr sodium chromate labelled neutrophils to umbilical vein EC monolayers was assayed in 96-well microtiter plates. Neutrophil chemotaxis was measured in Boyden microchemotaxis chambers.<br /><br /><strong>RESULTS: </strong>Tenidap sodium caused a dose related inhibition of neutrophil adhesion to EC, with 50 microM tenidap resulting in 51.8 +/- 4.0% (mean +/- SEM) inhibition of unstimulated adhesion and 46.1 +/- 2.6% inhibition of formyl-methionyl-leucyl-phenylalanine (FMLP) stimulated adhesion. A marked reduction in neutrophil chemotaxis in response to FMLP was also observed, with 50 microM and 100 microM tenidap leading to 83.4 +/- 8.5% and 92.1 +/- 8.5% (mean +/- SEM) inhibition respectively. The effect of tenidap on neutrophil adhesion to EC was not seen when neutrophils were preincubated with tenidap and then washed before adding to EC monolayers, suggesting an action upon surface molecules or in the cell membrane. Aspirin, indomethacin and phenylbutazone did not inhibit leukocyte adhesion, indicating that this action of tenidap may not be a consequence of inhibition of cyclooxygenase. The potency of tenidap was reduced by inclusion of serum or plasma in the culture medium, presumably due to protein binding.<br /><br /><strong>CONCLUSION: </strong>It is possible that inhibition of leukocyte-EC adhesion by tenidap sodium may contribute to the antiinflammatory effects of the drug."
1235717,Carballido et al. 1993,Interferon-alpha-2b enhances the natural killer activity of patients with transitional cell carcinoma of the bladder,"<strong>BACKGROUND: </strong>Transitional cell carcinoma (TCC) of the bladder is associated with alterations in the immune system of the host. The authors demonstrated that in patients with bladder carcinoma there is a negative correlation between the levels of natural killer (NK) activity and the clinical evolution and pathologic stages of disease.<br /><br /><strong>METHODS: </strong>The authors investigated the effect of various doses of recombinant interferon-alpha-2b (IFN-alpha-2b) for variable periods of culture on the nonmajor histocompatibility-restricted cytotoxic activity of peripheral blood mononuclear cells (PBMNC) with or without CD16 and CD3-depleted populations from patients with superficial (confined to the mucosa or lamina propria) and infiltrative (those infiltrating beyond the lamina propria) TCC of the bladder using 4-hour 51-sodium chromate (51Cr)-release cytotoxicity assays against both NK-sensitive (K562) and NK-resistant (JY) tumor target cells.<br /><br /><strong>RESULTS: </strong>The normal NK activity detected in PBMNC from patients with superficial TCC of the bladder can be significantly enhanced by short-term (18-hour) incubation with recombinant IFN-alpha (P &lt; 0.05). The depressed NK cytotoxic activity found in PBMNC from patients with infiltrative TCC can also be significantly enhanced, but not normalized, by short-term (18-hour) incubation with recombinant IFN-alpha (P &lt; 0.05). Short-term recombinant IFN-alpha-incubated PBMNC from patients with superficial, but not infiltrative, TCC of the bladder also showed marked cytotoxic activity against NK-resistant target cells. By selection with CD16 or CD3 monoclonal antibodies and complement, it was also found that the precursor and effector lymphocytes of this recombinant IFN-alpha-promoted cytotoxicity belong to NK lineage. In kinetic studies, it was found that the maximal levels of the recombinant IFN-alpha-promoted cytotoxic activity against NK-sensitive and NK-resistant target cells in PBMNC from patients with TCC were reached after 18 hours of culture.<br /><br /><strong>CONCLUSION: </strong>Recombinant IFN-alpha can enhance the nonmajor histocompatibility-restricted cytotoxic activity of PBMNC from patients with TCC of the bladder.","Interferon-alpha-2b enhances the natural killer activity of patients with transitional cell carcinoma of the bladder Abs: <strong>BACKGROUND: </strong>Transitional cell carcinoma (TCC) of the bladder is associated with alterations in the immune system of the host. The authors demonstrated that in patients with bladder carcinoma there is a negative correlation between the levels of natural killer (NK) activity and the clinical evolution and pathologic stages of disease.<br /><br /><strong>METHODS: </strong>The authors investigated the effect of various doses of recombinant interferon-alpha-2b (IFN-alpha-2b) for variable periods of culture on the nonmajor histocompatibility-restricted cytotoxic activity of peripheral blood mononuclear cells (PBMNC) with or without CD16 and CD3-depleted populations from patients with superficial (confined to the mucosa or lamina propria) and infiltrative (those infiltrating beyond the lamina propria) TCC of the bladder using 4-hour 51-sodium chromate (51Cr)-release cytotoxicity assays against both NK-sensitive (K562) and NK-resistant (JY) tumor target cells.<br /><br /><strong>RESULTS: </strong>The normal NK activity detected in PBMNC from patients with superficial TCC of the bladder can be significantly enhanced by short-term (18-hour) incubation with recombinant IFN-alpha (P &lt; 0.05). The depressed NK cytotoxic activity found in PBMNC from patients with infiltrative TCC can also be significantly enhanced, but not normalized, by short-term (18-hour) incubation with recombinant IFN-alpha (P &lt; 0.05). Short-term recombinant IFN-alpha-incubated PBMNC from patients with superficial, but not infiltrative, TCC of the bladder also showed marked cytotoxic activity against NK-resistant target cells. By selection with CD16 or CD3 monoclonal antibodies and complement, it was also found that the precursor and effector lymphocytes of this recombinant IFN-alpha-promoted cytotoxicity belong to NK lineage. In kinetic studies, it was found that the maximal levels of the recombinant IFN-alpha-promoted cytotoxic activity against NK-sensitive and NK-resistant target cells in PBMNC from patients with TCC were reached after 18 hours of culture.<br /><br /><strong>CONCLUSION: </strong>Recombinant IFN-alpha can enhance the nonmajor histocompatibility-restricted cytotoxic activity of PBMNC from patients with TCC of the bladder."
1235715,Sugiyama et al. 1993,"Influence of o-phenanthroline on DNA single-strand breaks, alkali-labile sites, glutathione reductase, and formation of chromium(V) in Chinese hamster V-79 cells treated with sodium chromate (VI)","The effect of the cell-permeable metal chelator o-phenanthroline (OP) on the formation of chromium(V), DNA breaks, alkali-labile sites, and enzyme inhibition of chromium(VI) was studied using Chinese hamster V-79 cells. Alkaline elution assays demonstrated that treatment with OP (100-500 microM) resulted in a dose-dependent decrease in cellular levels of either alkali-labile sites or the combination of alkali-labile sites plus DNA single-strand breaks caused by Na2CrO4. Cellular treatment with OP also attenuated the inhibition of glutathione reductase attributed to Na2CrO4. Under the same experimental conditions, the cellular uptake of chromate was not affected by OP. ESR studies revealed that cellular treatment with OP (100-500 microM) resulted in a concentration-dependent decrease in the level of chromium(V) intermediate in cells treated with Na2CrO4. Furthermore, OP inhibited the chromium(V) complex that formed during the reaction of Na2CrO4 with glutathione in vitro, resulting in the decrease of chromium(V)-mediated hydroxyl radical formation while neither the reduction of chromium(VI) nor the formation of the chromium(VI)-glutathione complex was affected, indicating that OP may react with chromium(V) but not with chromium(VI). These results suggest that the metal chelator OP decreases chromate-induced alkali-labile sites or the combination of alkali-labile sites plus DNA strand breaks, as well as chromium inhibition of glutathione reductase, possibly through its ability to directly decrease chromium(V) complex in cells.","Influence of o-phenanthroline on DNA single-strand breaks, alkali-labile sites, glutathione reductase, and formation of chromium(V) in Chinese hamster V-79 cells treated with sodium chromate (VI) Abs: The effect of the cell-permeable metal chelator o-phenanthroline (OP) on the formation of chromium(V), DNA breaks, alkali-labile sites, and enzyme inhibition of chromium(VI) was studied using Chinese hamster V-79 cells. Alkaline elution assays demonstrated that treatment with OP (100-500 microM) resulted in a dose-dependent decrease in cellular levels of either alkali-labile sites or the combination of alkali-labile sites plus DNA single-strand breaks caused by Na2CrO4. Cellular treatment with OP also attenuated the inhibition of glutathione reductase attributed to Na2CrO4. Under the same experimental conditions, the cellular uptake of chromate was not affected by OP. ESR studies revealed that cellular treatment with OP (100-500 microM) resulted in a concentration-dependent decrease in the level of chromium(V) intermediate in cells treated with Na2CrO4. Furthermore, OP inhibited the chromium(V) complex that formed during the reaction of Na2CrO4 with glutathione in vitro, resulting in the decrease of chromium(V)-mediated hydroxyl radical formation while neither the reduction of chromium(VI) nor the formation of the chromium(VI)-glutathione complex was affected, indicating that OP may react with chromium(V) but not with chromium(VI). These results suggest that the metal chelator OP decreases chromate-induced alkali-labile sites or the combination of alkali-labile sites plus DNA strand breaks, as well as chromium inhibition of glutathione reductase, possibly through its ability to directly decrease chromium(V) complex in cells."
1235713,Mullaney et al. 1993,Stimulation of D-aspartate efflux by mercuric chloride from rat primary astrocyte cultures,"Mercuric chloride (HgCl2; MC) was shown to increase D-aspartate release from preloaded astrocytes in a dose-dependent fashion. Two sulfhydryl (-SH) protecting agents, a cell membrane non-penetrating compound, reduced glutathione (GSH), and the membrane-permeable dithiothreitol (DTT), were found to inhibit the stimulatory action of MC on the efflux of radiolabeled D-aspartate. MC-induced D-aspartate release was completely inhibited by the addition of 1 mM DTT or GSH during the actual 5 min perfusion period with MC (5 microM). However, when added after MC treatment, this inhibition could not be sustained by GSH, while DTT fully inhibited the MC-induced release of D-aspartate. Neither DTT nor GSH alone had any effect on the rate of astrocytic D-aspartate release. Accordingly, it is postulated that the stimulatory effect exerted by MC on astrocytic D-aspartate release is associated with vulnerable -SH groups located within, but not on the surface of the cell membrane. Omission of Na+ from the perfusion solution did not accelerate MC-induced D-aspartate release, suggesting that reversal of the D-aspartate carrier can not be invoked to explain MC-induced D-aspartate release. Furthermore, MC did not appear to be associated with astrocytic swelling.","Stimulation of D-aspartate efflux by mercuric chloride from rat primary astrocyte cultures Abs: Mercuric chloride (HgCl2; MC) was shown to increase D-aspartate release from preloaded astrocytes in a dose-dependent fashion. Two sulfhydryl (-SH) protecting agents, a cell membrane non-penetrating compound, reduced glutathione (GSH), and the membrane-permeable dithiothreitol (DTT), were found to inhibit the stimulatory action of MC on the efflux of radiolabeled D-aspartate. MC-induced D-aspartate release was completely inhibited by the addition of 1 mM DTT or GSH during the actual 5 min perfusion period with MC (5 microM). However, when added after MC treatment, this inhibition could not be sustained by GSH, while DTT fully inhibited the MC-induced release of D-aspartate. Neither DTT nor GSH alone had any effect on the rate of astrocytic D-aspartate release. Accordingly, it is postulated that the stimulatory effect exerted by MC on astrocytic D-aspartate release is associated with vulnerable -SH groups located within, but not on the surface of the cell membrane. Omission of Na+ from the perfusion solution did not accelerate MC-induced D-aspartate release, suggesting that reversal of the D-aspartate carrier can not be invoked to explain MC-induced D-aspartate release. Furthermore, MC did not appear to be associated with astrocytic swelling."
1235710,Rowe and  Welch 1994,Assays of hemolytic toxins,"The ability to produce a cytolytic toxin contributes to the success of many organisms in a particular niche by such diverse means as lysis of a phagolysosomal membrane of the macrophage by hemolysin from the intracellular parasite Trypanosoma cruzi, disruption of leukocyte activity by the Escherichia coli hemolysin, and destruction of invading bacteria by hemolysin from the annelid Glycera dibranchiata. The relative contribution of erythrocyte lysis to survival of the cytolysin producer is still under investigation. Nevertheless, the hemolytic phenotype is both a powerful tool for identifying novel cytolysins and a convenient marker for studying cytolytic activity in established toxins.","Assays of hemolytic toxins Abs: The ability to produce a cytolytic toxin contributes to the success of many organisms in a particular niche by such diverse means as lysis of a phagolysosomal membrane of the macrophage by hemolysin from the intracellular parasite Trypanosoma cruzi, disruption of leukocyte activity by the Escherichia coli hemolysin, and destruction of invading bacteria by hemolysin from the annelid Glycera dibranchiata. The relative contribution of erythrocyte lysis to survival of the cytolysin producer is still under investigation. Nevertheless, the hemolytic phenotype is both a powerful tool for identifying novel cytolysins and a convenient marker for studying cytolytic activity in established toxins."
1235707,El Sayed and  Bazex 1994,Airborne contact dermatitis from chromate in cement with recall dermatitis on patch testing,BIOSIS COPYRIGHT: BIOL ABS. RRM CASE STUDY NOTE HUMAN CORTICOSTEROID THERAPY POTASSIUM DICHROMATE HEALTH HAZARD,Airborne contact dermatitis from chromate in cement with recall dermatitis on patch testing Abs: BIOSIS COPYRIGHT: BIOL ABS. RRM CASE STUDY NOTE HUMAN CORTICOSTEROID THERAPY POTASSIUM DICHROMATE HEALTH HAZARD
1235706,Appenroth et al. 1994,The ambiguous effect of ascorbic acid on chromate induced proteinuria in rats,"The influence of ascorbic acid (AA, 5 g/kg body weight) on chromate (Cr, 10 mg/kg) induced proteinuria, which is a sensitive parameter of its nephrotoxicity, was investigated in adult female Wistar rats. The concentrations of Cr and ascorbic acid (AA) were determined in renal tissue. Cr nephrotoxicity is related to its intracellular reduction from Cr(VI) to Cr(III). Proteinuria was completely prevented by enhancement of extracellular reduction of Cr(VI) to Cr(III) followed by rapid renal excretion when Cr and AA were given concomitantly. With an interval up to 1 h between Cr and AA, proteinuria was decreased probably by the radical scavenging function of AA. At an interval of 3 h AA enhanced Cr toxicity by increased intracellular Cr reduction. If the interval was increased to 5 h or if Cr was given 24 h after AA, no influence of AA could be detected. Our results confirm that AA is a very effective reductant of Cr which can influence Cr nephrotoxicity in very high concentrations. It depends on the interval between Cr and AA administration whether or not there is a beneficial effect of AA in Cr nephrotoxicity.","The ambiguous effect of ascorbic acid on chromate induced proteinuria in rats Abs: The influence of ascorbic acid (AA, 5 g/kg body weight) on chromate (Cr, 10 mg/kg) induced proteinuria, which is a sensitive parameter of its nephrotoxicity, was investigated in adult female Wistar rats. The concentrations of Cr and ascorbic acid (AA) were determined in renal tissue. Cr nephrotoxicity is related to its intracellular reduction from Cr(VI) to Cr(III). Proteinuria was completely prevented by enhancement of extracellular reduction of Cr(VI) to Cr(III) followed by rapid renal excretion when Cr and AA were given concomitantly. With an interval up to 1 h between Cr and AA, proteinuria was decreased probably by the radical scavenging function of AA. At an interval of 3 h AA enhanced Cr toxicity by increased intracellular Cr reduction. If the interval was increased to 5 h or if Cr was given 24 h after AA, no influence of AA could be detected. Our results confirm that AA is a very effective reductant of Cr which can influence Cr nephrotoxicity in very high concentrations. It depends on the interval between Cr and AA administration whether or not there is a beneficial effect of AA in Cr nephrotoxicity."
1235702,Angulo et al. 1994,Golgi-Colonnier method: correlation of the degree of chromium reduction and pH change with quality of staining,"We examined the role of chromium reduction in the Golgi-Colonnier method, correlating the quality of neuronal impregnation with the levels of hexavalent (CrVI) and trivalent (CrIII) chromium in the tissue and in the chromation fluid (CF). The concentrations of both chromium species were assessed by measuring spectrophotometrically the CrVI before and after oxidizing the sample and by calculating the ratio of CrVI to total chromium (chromium ratio, CrR). The CrR was almost identical in the tissue and the CF, decreasing exponentially during chromation due to a progressive consumption of CrVI to form CrIII. Satisfactory cell impregnation was obtained only when the CrR was 0.45-0.7, regardless of other factors. The CrR values could be accurately predicted by the pH increase of the CF; this increase has proven to be a most reliable criterion to decide the endpoint of the chromation process. The dependence of cell staining on the [CrIII], together with the well-known ability of this species to bridge proteins, suggests that the key event for cell impregnation is the cross-linking of neuronal proteins by CrIII polymers.","Golgi-Colonnier method: correlation of the degree of chromium reduction and pH change with quality of staining Abs: We examined the role of chromium reduction in the Golgi-Colonnier method, correlating the quality of neuronal impregnation with the levels of hexavalent (CrVI) and trivalent (CrIII) chromium in the tissue and in the chromation fluid (CF). The concentrations of both chromium species were assessed by measuring spectrophotometrically the CrVI before and after oxidizing the sample and by calculating the ratio of CrVI to total chromium (chromium ratio, CrR). The CrR was almost identical in the tissue and the CF, decreasing exponentially during chromation due to a progressive consumption of CrVI to form CrIII. Satisfactory cell impregnation was obtained only when the CrR was 0.45-0.7, regardless of other factors. The CrR values could be accurately predicted by the pH increase of the CF; this increase has proven to be a most reliable criterion to decide the endpoint of the chromation process. The dependence of cell staining on the [CrIII], together with the well-known ability of this species to bridge proteins, suggests that the key event for cell impregnation is the cross-linking of neuronal proteins by CrIII polymers."
1235701,Appenroth 1994,Ontogenic changes in the nephrotoxicity of chromate correlate with the glutathione oxidoreduction system,"The role of GSH concentration and GSSG reductase activity in age differences in chromate nephrotoxicity was investigated. Young and adult rats were injected with 2 and 1 mg sodium chromate/100 g body weight (BW), respectively, which led to equal Cr concentrations in renal tissue. Cr nephrotoxicity was lower in young than in adult rats. It was shown that from 30 minutes after the chromate injection GSSG reductase activity in renal tissue was increased in adult but decreased in young rats by the chromate. GSSG reductase activity was increased in young rats by pretreatment with phenobarbital. The consequence was an enhancement of chromate nephrotoxicity as shown by proteinuria. Renal GSH concentration is lower in young rats and limiting for chromate reduction in vitro in these animals. Therefore, GSH concentration was increased by pretreatment with N-acetylcysteine, which enhanced chromate nephrotoxicity significantly. These results reflect the important role of the GSH oxidoreduction system in chromate nephrotoxicity and its relationship to age differences.","Ontogenic changes in the nephrotoxicity of chromate correlate with the glutathione oxidoreduction system Abs: The role of GSH concentration and GSSG reductase activity in age differences in chromate nephrotoxicity was investigated. Young and adult rats were injected with 2 and 1 mg sodium chromate/100 g body weight (BW), respectively, which led to equal Cr concentrations in renal tissue. Cr nephrotoxicity was lower in young than in adult rats. It was shown that from 30 minutes after the chromate injection GSSG reductase activity in renal tissue was increased in adult but decreased in young rats by the chromate. GSSG reductase activity was increased in young rats by pretreatment with phenobarbital. The consequence was an enhancement of chromate nephrotoxicity as shown by proteinuria. Renal GSH concentration is lower in young rats and limiting for chromate reduction in vitro in these animals. Therefore, GSH concentration was increased by pretreatment with N-acetylcysteine, which enhanced chromate nephrotoxicity significantly. These results reflect the important role of the GSH oxidoreduction system in chromate nephrotoxicity and its relationship to age differences."
1235700,Bridgewater et al. 1994,DNA polymerase arrest by adducted trivalent chromium,"Carcinogenic chromium (Cr6+) enters cells via the sulfate transport system and undergoes intracellular reduction to trivalent chromium, which strongly adducts to DNA. In this study, the effect of adducted trivalent chromium on in vitro DNA synthesis was analyzed with a polymerase-arrest assay in which prematurely terminated replication products were separated on a DNA sequencing gel. A synthetic DNA replication template was treated with increasing concentrations of chromium(III) chloride. The two lowest chromium doses used resulted in biologically relevant adduct levels (6 and 21 adducts per 1,000 DNA nucleotides) comparable with those measured in nuclear matrix DNA from cells treated with a 50% cytotoxic dose of sodium chromate in vivo. In vitro replication of the chromium-treated template DNA using the Sequenase version 2.0 T7 DNA polymerase (United States Biochemical Corp., Cleveland, OH) resulted in dose-dependent polymerase arrest beginning at the lowest adduct levels analyzed. The pattern of polymerase arrest remained consistent as chromium adduct levels increased, with the most intense arrest sites occurring 1 base upstream of guanine residues on the template strand. Replication by the DNA polymerase I large (Klenow) fragment as well as by unmodified T7 DNA polymerase also resulted in similar chromium-induced polymerase arrest. Interstrand cross-linking between complementary strands was detected in template DNA containing 62, 111, and 223 chromium adducts per 1,000 DNA nucleotides but not in template containing 6 or 21 adducts per 1,000 DNA nucleotides, in which arrest nevertheless did occur. Low-level, dose-dependent interstrand cross-linking between primer and template DNA, however, was detectable even at the lowest chromium dose analyzed. Since only 9% of chromium adducts resulted in polymerase arrest in this system, we hypothesized that arrest occurred when the enzyme encountered chromium-mediated interstrand DNA-DNA cross-links between either the template and a separate DNA molecule or the template and its complementary strand in the same molecule. These results suggest that the obstruction of DNA replication by chromium-mediated DNA-DNA cross-links is a potential mechanism of chromium-induced genotoxicity in vivo.","DNA polymerase arrest by adducted trivalent chromium Abs: Carcinogenic chromium (Cr6+) enters cells via the sulfate transport system and undergoes intracellular reduction to trivalent chromium, which strongly adducts to DNA. In this study, the effect of adducted trivalent chromium on in vitro DNA synthesis was analyzed with a polymerase-arrest assay in which prematurely terminated replication products were separated on a DNA sequencing gel. A synthetic DNA replication template was treated with increasing concentrations of chromium(III) chloride. The two lowest chromium doses used resulted in biologically relevant adduct levels (6 and 21 adducts per 1,000 DNA nucleotides) comparable with those measured in nuclear matrix DNA from cells treated with a 50% cytotoxic dose of sodium chromate in vivo. In vitro replication of the chromium-treated template DNA using the Sequenase version 2.0 T7 DNA polymerase (United States Biochemical Corp., Cleveland, OH) resulted in dose-dependent polymerase arrest beginning at the lowest adduct levels analyzed. The pattern of polymerase arrest remained consistent as chromium adduct levels increased, with the most intense arrest sites occurring 1 base upstream of guanine residues on the template strand. Replication by the DNA polymerase I large (Klenow) fragment as well as by unmodified T7 DNA polymerase also resulted in similar chromium-induced polymerase arrest. Interstrand cross-linking between complementary strands was detected in template DNA containing 62, 111, and 223 chromium adducts per 1,000 DNA nucleotides but not in template containing 6 or 21 adducts per 1,000 DNA nucleotides, in which arrest nevertheless did occur. Low-level, dose-dependent interstrand cross-linking between primer and template DNA, however, was detectable even at the lowest chromium dose analyzed. Since only 9% of chromium adducts resulted in polymerase arrest in this system, we hypothesized that arrest occurred when the enzyme encountered chromium-mediated interstrand DNA-DNA cross-links between either the template and a separate DNA molecule or the template and its complementary strand in the same molecule. These results suggest that the obstruction of DNA replication by chromium-mediated DNA-DNA cross-links is a potential mechanism of chromium-induced genotoxicity in vivo."
1235699,Sugiyama and  Tsuzuki 1994,Effect of glutathione depletion on formation of paramagnetic chromium in Chinese hamster V-79 cells,"Incubation of Chinese hamster V-79 cells with either buthionine sulfoximine (BSO) or diethylmaleate (DEM) prior to exposure to Na2CrO4 resulted in a depletion of GSH. ESR study shows that the depletion of GSH by BSO caused an increase in the cellular level of Cr(V) intermediate without affecting the level of Cr(III) complex, whereas the levels of Cr(V) and (III) were both suppressed by the depletion of GSH by DEM. GSH depletion by DEM decreased cellular uptake of chromate more than that by BSO. Glutathione reductase activity in cells, which is capable of reducing Cr(VI), was unaffected by BSO, however a strong inhibition was observed in cells treated with DEM, indicating that DEM affects not only GSH levels but also Cr(VI)-reducing enzyme activity. Thus, the depletion of GSH in cells increases Cr(V) formation, based upon the effect of BSO. The role of intracellular GSH in Cr(VI) reduction is discussed.","Effect of glutathione depletion on formation of paramagnetic chromium in Chinese hamster V-79 cells Abs: Incubation of Chinese hamster V-79 cells with either buthionine sulfoximine (BSO) or diethylmaleate (DEM) prior to exposure to Na2CrO4 resulted in a depletion of GSH. ESR study shows that the depletion of GSH by BSO caused an increase in the cellular level of Cr(V) intermediate without affecting the level of Cr(III) complex, whereas the levels of Cr(V) and (III) were both suppressed by the depletion of GSH by DEM. GSH depletion by DEM decreased cellular uptake of chromate more than that by BSO. Glutathione reductase activity in cells, which is capable of reducing Cr(VI), was unaffected by BSO, however a strong inhibition was observed in cells treated with DEM, indicating that DEM affects not only GSH levels but also Cr(VI)-reducing enzyme activity. Thus, the depletion of GSH in cells increases Cr(V) formation, based upon the effect of BSO. The role of intracellular GSH in Cr(VI) reduction is discussed."
1235698,Handley and  Burrows 1994,Dermatitis from hexavalent chromate in the accelerator of an epoxy sealant (PR1422) used in the aircraft industry,"4 aircraft construction workers developed allergic contact dermatitis of the hands and forearms. The allergen was hexavalent chromate in the accelerating solution of an epoxy-based sealant (PR1422). Although chromate dermatitis from an epoxy resin has been described, epoxy system accelerators are a hitherto unrecognized source of occupational chromate dermatitis.","Dermatitis from hexavalent chromate in the accelerator of an epoxy sealant (PR1422) used in the aircraft industry Abs: 4 aircraft construction workers developed allergic contact dermatitis of the hands and forearms. The allergen was hexavalent chromate in the accelerating solution of an epoxy-based sealant (PR1422). Although chromate dermatitis from an epoxy resin has been described, epoxy system accelerators are a hitherto unrecognized source of occupational chromate dermatitis."
1235697,Martin and  Edwards 1994,Interferon-gamma enhances monocyte cytotoxicity via enhanced reactive oxygen intermediate production. Absence of an effect on macrophage cytotoxicity is due to failure to enhance reactive nitrogen intermediate production,"Interferon-gamma (IFN-gamma) enhanced the cytotoxic capability of freshly isolated human blood monocytes but failed to enhance the tumoricidal competence of monocyte-derived macrophages. Treatment of monocytes with IFN-gamma (100 U/ml) caused a significant increase (P &lt; 0.001) in lucigenin-dependent chemiluminescence and O2- production stimulated by N-formyl-L-methionyl-L-leucyl-L-phenylalanine (FMLP) during the first few days in culture but IFN-gamma was unable to prevent the decline to negligible levels of chemiluminescence and O2- production which occurred during the later days in vitro. Culture of monocytes in the presence of IFN-gamma had no effect on phorbol 12-myristate 13-acetate (PMA)-stimulated O2- production. However, IFN-gamma decreased PMA-stimulated lucigenin-dependent chemiluminescence during the first 24 hr in vitro but then significantly enhanced (P &lt; 0.001) chemiluminescence after 2-4 days in culture. IFN-gamma was unable to prevent the eventual decline to undetectable levels in PMA-stimulated chemiluminescence during the later days in vitro. Nitrite production by macrophages was unaffected by IFN-gamma treatment. It is concluded therefore, that IFN-gamma enhanced the cytotoxicity of freshly isolated human blood monocytes by increasing reactive oxygen intermediate generation but was unable to enhance the tumoricidal competence of macrophages as reactive nitrogen intermediate production was unaffected.","Interferon-gamma enhances monocyte cytotoxicity via enhanced reactive oxygen intermediate production. Absence of an effect on macrophage cytotoxicity is due to failure to enhance reactive nitrogen intermediate production Abs: Interferon-gamma (IFN-gamma) enhanced the cytotoxic capability of freshly isolated human blood monocytes but failed to enhance the tumoricidal competence of monocyte-derived macrophages. Treatment of monocytes with IFN-gamma (100 U/ml) caused a significant increase (P &lt; 0.001) in lucigenin-dependent chemiluminescence and O2- production stimulated by N-formyl-L-methionyl-L-leucyl-L-phenylalanine (FMLP) during the first few days in culture but IFN-gamma was unable to prevent the decline to negligible levels of chemiluminescence and O2- production which occurred during the later days in vitro. Culture of monocytes in the presence of IFN-gamma had no effect on phorbol 12-myristate 13-acetate (PMA)-stimulated O2- production. However, IFN-gamma decreased PMA-stimulated lucigenin-dependent chemiluminescence during the first 24 hr in vitro but then significantly enhanced (P &lt; 0.001) chemiluminescence after 2-4 days in culture. IFN-gamma was unable to prevent the eventual decline to undetectable levels in PMA-stimulated chemiluminescence during the later days in vitro. Nitrite production by macrophages was unaffected by IFN-gamma treatment. It is concluded therefore, that IFN-gamma enhanced the cytotoxicity of freshly isolated human blood monocytes by increasing reactive oxygen intermediate generation but was unable to enhance the tumoricidal competence of macrophages as reactive nitrogen intermediate production was unaffected."
1235695,Shi et al. 1994,"Chromate-mediated free radical generation from cysteine, penicillamine, hydrogen peroxide, and lipid hydroperoxides","The Cr(VI)-mediated free radical generation from cysteine, penicillamine, hydrogen peroxide, and model lipid hydroperoxides was investigated utilizing the electron spin resonance (ESR) spin trapping technique. Incubation of Cr(VI) with cysteine (Cys) generated cysteinyl radical. Radical yield depended on the relative concentrations of Cr(VI) and Cys. The radical generation became detectable at a cysteine:Cr(VI) ratio of about 5, reached its highest level at a ratio of 30, and declined thereafter. Cr(VI) or Cys alone did not generate a detectable amount of free radicals. Similar results were obtained with penicillamine. Incubation of Cr(VI), Cys or penicillamine and H2O2 led to hydroxyl (.OH) radical generation, which was verified by quantitative competition experiments utilizing ethanol. The mechanism for .OH radical generation is considered to be a Cr(VI)-mediated Fenton-like reaction. When model lipid hydroperoxides such as t-butyl hydroperoxide and cumene hydroperoxide were used in place of H2O2, hydroperoxide-derived free radicals were produced. Since thiols, such as Cys, exist in cellular systems at relatively high concentrations, Cr(VI)-mediated free radical generation in the presence of thiols may participate in the mechanisms of Cr(VI)-induced toxicity and carcinogenesis.","Chromate-mediated free radical generation from cysteine, penicillamine, hydrogen peroxide, and lipid hydroperoxides Abs: The Cr(VI)-mediated free radical generation from cysteine, penicillamine, hydrogen peroxide, and model lipid hydroperoxides was investigated utilizing the electron spin resonance (ESR) spin trapping technique. Incubation of Cr(VI) with cysteine (Cys) generated cysteinyl radical. Radical yield depended on the relative concentrations of Cr(VI) and Cys. The radical generation became detectable at a cysteine:Cr(VI) ratio of about 5, reached its highest level at a ratio of 30, and declined thereafter. Cr(VI) or Cys alone did not generate a detectable amount of free radicals. Similar results were obtained with penicillamine. Incubation of Cr(VI), Cys or penicillamine and H2O2 led to hydroxyl (.OH) radical generation, which was verified by quantitative competition experiments utilizing ethanol. The mechanism for .OH radical generation is considered to be a Cr(VI)-mediated Fenton-like reaction. When model lipid hydroperoxides such as t-butyl hydroperoxide and cumene hydroperoxide were used in place of H2O2, hydroperoxide-derived free radicals were produced. Since thiols, such as Cys, exist in cellular systems at relatively high concentrations, Cr(VI)-mediated free radical generation in the presence of thiols may participate in the mechanisms of Cr(VI)-induced toxicity and carcinogenesis."
1235694,Fitzgerald and  English 1994,Lymphoedema of the hands as a complication of chronic allergic contact dermatitis,"A case of hand lymphedema probably caused by chromate or cobalt (7440484) induced allergic contact dermatitis was summarized. A 40 year old male with severe fissured dermatitis of the hands was evaluated at a dermatology clinic in 1982. He had worked as a building laborer for 20 years. He was not atopic. Patch testing with the European standard allergen series revealed positive reactions to potassium-dichromate (7778509) and cobalt-chloride (7646799). He continued in the same occupation and suffered several episodes of hand dermatitis which did not respond to treatment with topical corticosteroids. He also had recurrent episodes of streptococcal cellulitis on each hand. He was hospitalized in 1993 complaining of persistent swelling of his hands. The swelling prevented him from working. Examination revealed marked nonpitting edema of both hands accompanied by varying degrees of chronic dermatitis. No upper limb or systemic lymphadenopathy was detected. The authors conclude that in the absence of any other identifiable cause, the patient's lymphedema has to be attributed to his chronic dermatitis. Although chronic dermatitis itself has not been recognized as causing lymphedema, it is possible that the recurrent episodes of streptococcal cellulitis may have rendered the patient susceptible to lymphedema.","Lymphoedema of the hands as a complication of chronic allergic contact dermatitis Abs: A case of hand lymphedema probably caused by chromate or cobalt (7440484) induced allergic contact dermatitis was summarized. A 40 year old male with severe fissured dermatitis of the hands was evaluated at a dermatology clinic in 1982. He had worked as a building laborer for 20 years. He was not atopic. Patch testing with the European standard allergen series revealed positive reactions to potassium-dichromate (7778509) and cobalt-chloride (7646799). He continued in the same occupation and suffered several episodes of hand dermatitis which did not respond to treatment with topical corticosteroids. He also had recurrent episodes of streptococcal cellulitis on each hand. He was hospitalized in 1993 complaining of persistent swelling of his hands. The swelling prevented him from working. Examination revealed marked nonpitting edema of both hands accompanied by varying degrees of chronic dermatitis. No upper limb or systemic lymphadenopathy was detected. The authors conclude that in the absence of any other identifiable cause, the patient's lymphedema has to be attributed to his chronic dermatitis. Although chronic dermatitis itself has not been recognized as causing lymphedema, it is possible that the recurrent episodes of streptococcal cellulitis may have rendered the patient susceptible to lymphedema."
1235693,Sourek and  Oravec 1994,Antitumor activity of bacterial endotoxins and their subunits in in vitro test,"The tumoricidal effect of endotoxins and their subunits of Shigella dysenteriae serovar 1 of both growth forms and certain other representatives of the Enterobacteriaceae family was tested against Németh-Kellner mouse lymphoma cells using an in vitro assay based on the use of sodium chromate solution yielding labelled hexavalent 51Cr ions. The most effective in vitro activity was evidenced in both growth forms by S. dysenteriae 1 lipopolysaccharide-protein complex (LPSP) (76-92%), lipid A and lipoid B isolated from LPS (77-82%) and lipid A and lipoid B from LPSP (53-70%). A direct dependence of the level of the Limulus test and pyrogenicity on the tumoricidal activity of a preparation was not demonstrated. The influence of selected cations (Cu, Fe, Ca, Mg, Zn) bound to selected substances on antitumor activity was monitored. The method of probit analysis is recommended as it enables estimation, based on a number of concentrations, of the regression line of probable effectiveness of a given preparation.","Antitumor activity of bacterial endotoxins and their subunits in in vitro test Abs: The tumoricidal effect of endotoxins and their subunits of Shigella dysenteriae serovar 1 of both growth forms and certain other representatives of the Enterobacteriaceae family was tested against Németh-Kellner mouse lymphoma cells using an in vitro assay based on the use of sodium chromate solution yielding labelled hexavalent 51Cr ions. The most effective in vitro activity was evidenced in both growth forms by S. dysenteriae 1 lipopolysaccharide-protein complex (LPSP) (76-92%), lipid A and lipoid B isolated from LPS (77-82%) and lipid A and lipoid B from LPSP (53-70%). A direct dependence of the level of the Limulus test and pyrogenicity on the tumoricidal activity of a preparation was not demonstrated. The influence of selected cations (Cu, Fe, Ca, Mg, Zn) bound to selected substances on antitumor activity was monitored. The method of probit analysis is recommended as it enables estimation, based on a number of concentrations, of the regression line of probable effectiveness of a given preparation."
1235692,Mariani et al. 1994,Standardization of a micro-cytotoxicity assay for human natural killer cell lytic activity,"Cytotoxicity assays are widely used to evaluate the functional activity of NK and T cells against tumour target cells and the release of radioactive sodium chromate from labelled target cells is still the most commonly used marker of target lysis in culture supernatants. We describe here the standardization of a micro-cytotoxicity test in which the number of cytolytic effector and tumour target cells have been decreased by a factor of 10. The release obtained by 500 tumour target cells was compared with the release obtained by 5000 target cells in the standard cytotoxicity assay for target:effector cell ratios from 1:1 to 1:100. Both gamma and beta emissions of the 51Cr isotope were evaluated to determine the assay release. The results obtained by the micro-cytotoxicity assay (500 target cells) were comparable to those of the standard assay (5000 target cells) and 51Cr release evaluation using the gamma counter was the most sensitive method of determining lytic activity using 500 tumour target cells. beta counter evaluation using solid phase scintillation was found to be a reproducible alternative method, even if the lytic curves cannot be compared with those obtained using the traditional method.","Standardization of a micro-cytotoxicity assay for human natural killer cell lytic activity Abs: Cytotoxicity assays are widely used to evaluate the functional activity of NK and T cells against tumour target cells and the release of radioactive sodium chromate from labelled target cells is still the most commonly used marker of target lysis in culture supernatants. We describe here the standardization of a micro-cytotoxicity test in which the number of cytolytic effector and tumour target cells have been decreased by a factor of 10. The release obtained by 500 tumour target cells was compared with the release obtained by 5000 target cells in the standard cytotoxicity assay for target:effector cell ratios from 1:1 to 1:100. Both gamma and beta emissions of the 51Cr isotope were evaluated to determine the assay release. The results obtained by the micro-cytotoxicity assay (500 target cells) were comparable to those of the standard assay (5000 target cells) and 51Cr release evaluation using the gamma counter was the most sensitive method of determining lytic activity using 500 tumour target cells. beta counter evaluation using solid phase scintillation was found to be a reproducible alternative method, even if the lytic curves cannot be compared with those obtained using the traditional method."
1235691,Wardrop et al. 1994,Evaluation of an additive solution for preservation of canine red blood cells,"The effect of an additive preservative solution on canine red blood cell posttransfusion viability (PTV) and on selected canine red blood cell biochemical parameters was studied. One unit (450 mL) of blood was collected from 6 clinically normal dogs into the anticoagulant citrate phosphate dextrose, centrifuged, and the plasma removed. The red blood cells were then suspended in 100 mL of a saline, adenine, dextrose, and mannitol solution and stored at 4 degrees C. Aliquots were removed for study at 1, 10, 20, 30, 37, and 44 days. The 24-hour PTV of autologous red blood cells was determined using a sodium chromate (51Cr) label. Red blood cell concentrations of 2,3-diphosphoglycerate (2,3-DPG), adenosine-5'-triphosphate (ATP), and pH were also determined. Canine red blood cell PTV, pH, ATP, and 2,3-DPG concentrations decreased during storage (P &lt; .05). The PTV decreased from 94% using day 1 red blood cells to 80% and 75% using day 37 and day 44 red blood cells, respectively (P &lt; .05). Although the mean PTV of the day 44 stored units equaled the Food and Drug Administration (FDA) minimum standard for human red blood cells, the PTV was substandard in 75% of the day 44 units. The FDA standard was exceeded in 83% of the day 37 units. It was concluded that 37-day-old canine red blood cells preserved with a saline, adenine, dextrose, and mannitol solution are of acceptable quality for transfusion.","Evaluation of an additive solution for preservation of canine red blood cells Abs: The effect of an additive preservative solution on canine red blood cell posttransfusion viability (PTV) and on selected canine red blood cell biochemical parameters was studied. One unit (450 mL) of blood was collected from 6 clinically normal dogs into the anticoagulant citrate phosphate dextrose, centrifuged, and the plasma removed. The red blood cells were then suspended in 100 mL of a saline, adenine, dextrose, and mannitol solution and stored at 4 degrees C. Aliquots were removed for study at 1, 10, 20, 30, 37, and 44 days. The 24-hour PTV of autologous red blood cells was determined using a sodium chromate (51Cr) label. Red blood cell concentrations of 2,3-diphosphoglycerate (2,3-DPG), adenosine-5'-triphosphate (ATP), and pH were also determined. Canine red blood cell PTV, pH, ATP, and 2,3-DPG concentrations decreased during storage (P &lt; .05). The PTV decreased from 94% using day 1 red blood cells to 80% and 75% using day 37 and day 44 red blood cells, respectively (P &lt; .05). Although the mean PTV of the day 44 stored units equaled the Food and Drug Administration (FDA) minimum standard for human red blood cells, the PTV was substandard in 75% of the day 44 units. The FDA standard was exceeded in 83% of the day 37 units. It was concluded that 37-day-old canine red blood cells preserved with a saline, adenine, dextrose, and mannitol solution are of acceptable quality for transfusion."
1235689,Xu et al. 1994,Preferential formation and repair of chromium-induced DNA adducts and DNA--protein crosslinks in nuclear matrix DNA,"The distributions of chromium-DNA adducts and DNA-protein crosslinks induced by treatment of intact CHO cells with carcinogenic chromium were examined in distinct chromatin subtractions: a chromatin subtraction released by digestion of isolated nuclei with micrococcal nuclease (1SF, 14% of total nuclear DNA), bulk chromatin (74% of total DNA) and a nuclear matrix fraction (12% of total DNA). The identity of the matrix fraction was confirmed by hybridization of DNA from each subtraction with a cDNA probe prepared from total mRNA isolated from CHO cells, which showed that the 1SF and nuclear matrix fractions were 23- and 3.8-fold enriched in actively transcribed genes respectively, compared to total unfractionated DNA. Immediately following treatment of cells with 150 ?M sodium chromate for 2 h the binding of chromium to each chromatin fraction was found to be non-uniform. Compared with total unfractionated nuclei, the nuclear matrix fractions were enriched in chromatin-bound chromium (3.4-fold), whereas the bulk chromatin fraction was relatively depleted (0.5-fold). Approximately 13% of nuclear chromium was associated with the detergent-soluble lipid component of nuclei. A similar distribution of chromatin-bound chromium was also apparent 24 h after the chromate treatment. Immediately after the 2 h chromate treatment, chromium-DNA adducts were detected in all the chromatin subtractions. Total nuclear and bulk chromatin DNA contained similar levels of this type of damage. The 1SF fraction was depleted approximately 3-fold in this type of damage compared with total nuclear DNA. In contrast, the nuclear matrix was markedly enriched in chromium-DNA adducts (approximately 4-fold compared with total nuclear DNA) at this time. As previously demonstrated, chromium-DNA adducts in total nuclear DNA decreased within the first 24 h, but thereafter persisted at a similar level. Chromium-DNA adducts in nuclear matrix DNA also reached maximum levels at the end of the 2 h treatment and decreased to 68% and 39% of this level by 24 and 48 h after treatment respectively. In contrast, the adduct levels in the 1SF and bulk chromatin fractions did not change up to 48 h after treatment Chromium-induced DNA-protein crosslinks, which were stable to 8 M urea and 2% SDS, occurred almost exclusively in the nuclear matrix fraction. The crosslinks in this fraction reached a maximumlevel at the end of the 2 h treatment, but returned to control levels 24 h later. Because cell division was completely blocked and no redistribution of chromatin was detectable, the loss of these lesions probably represents true repair and the residual persistent adducts represent repair-resistant lesions. Treatment of cells synchronized in G1 of the cell cycle and in vitro treatment of isolated nuclei with trivalent chromium both yielded preferential adduct formation in nuclear matrix DNA, indicating that the non-random distribution of lesions was due to a structural predisposition of this chromatin subtraction and not accumulation of arrested replication forksor transcription bubbles in the matrix. These results indicate that chromium-induced DNA damage is both formed and repaired preferentially in nuclear matrix DNA.","Preferential formation and repair of chromium-induced DNA adducts and DNA--protein crosslinks in nuclear matrix DNA Abs: The distributions of chromium-DNA adducts and DNA-protein crosslinks induced by treatment of intact CHO cells with carcinogenic chromium were examined in distinct chromatin subtractions: a chromatin subtraction released by digestion of isolated nuclei with micrococcal nuclease (1SF, 14% of total nuclear DNA), bulk chromatin (74% of total DNA) and a nuclear matrix fraction (12% of total DNA). The identity of the matrix fraction was confirmed by hybridization of DNA from each subtraction with a cDNA probe prepared from total mRNA isolated from CHO cells, which showed that the 1SF and nuclear matrix fractions were 23- and 3.8-fold enriched in actively transcribed genes respectively, compared to total unfractionated DNA. Immediately following treatment of cells with 150 ?M sodium chromate for 2 h the binding of chromium to each chromatin fraction was found to be non-uniform. Compared with total unfractionated nuclei, the nuclear matrix fractions were enriched in chromatin-bound chromium (3.4-fold), whereas the bulk chromatin fraction was relatively depleted (0.5-fold). Approximately 13% of nuclear chromium was associated with the detergent-soluble lipid component of nuclei. A similar distribution of chromatin-bound chromium was also apparent 24 h after the chromate treatment. Immediately after the 2 h chromate treatment, chromium-DNA adducts were detected in all the chromatin subtractions. Total nuclear and bulk chromatin DNA contained similar levels of this type of damage. The 1SF fraction was depleted approximately 3-fold in this type of damage compared with total nuclear DNA. In contrast, the nuclear matrix was markedly enriched in chromium-DNA adducts (approximately 4-fold compared with total nuclear DNA) at this time. As previously demonstrated, chromium-DNA adducts in total nuclear DNA decreased within the first 24 h, but thereafter persisted at a similar level. Chromium-DNA adducts in nuclear matrix DNA also reached maximum levels at the end of the 2 h treatment and decreased to 68% and 39% of this level by 24 and 48 h after treatment respectively. In contrast, the adduct levels in the 1SF and bulk chromatin fractions did not change up to 48 h after treatment Chromium-induced DNA-protein crosslinks, which were stable to 8 M urea and 2% SDS, occurred almost exclusively in the nuclear matrix fraction. The crosslinks in this fraction reached a maximumlevel at the end of the 2 h treatment, but returned to control levels 24 h later. Because cell division was completely blocked and no redistribution of chromatin was detectable, the loss of these lesions probably represents true repair and the residual persistent adducts represent repair-resistant lesions. Treatment of cells synchronized in G1 of the cell cycle and in vitro treatment of isolated nuclei with trivalent chromium both yielded preferential adduct formation in nuclear matrix DNA, indicating that the non-random distribution of lesions was due to a structural predisposition of this chromatin subtraction and not accumulation of arrested replication forksor transcription bubbles in the matrix. These results indicate that chromium-induced DNA damage is both formed and repaired preferentially in nuclear matrix DNA."
1235688,Stathakis and  Cassidy 1994,Cationic polymers for selectivity control in the capillary electrophoretic separation of inorganic anions,"The capillary electrophoretic (CE) separation of the inorganic anions bromide, chloride, nitrate, nitrite, fluoride, sulfate and phosphate is described in 0.005 mol/L sodium chromate electrolyte in the presence of soluble polydisperse ionic polymers (polyelectrolytes). The cationic polyelectrolytes used were as follows: poly(1,1-dimethyl-3,5-dimethylenepiperidinium) chromate, hexadimethrine chromate, poly(1,1-dimethyl-3,5-dimethylenepyrrolidinium) chromate and ((diethylamino)ethyl)-dextran chromate in the concentration range 0.004-0.6% (w/v). These polyelectrolytes were shown to be capable of reversing the direction of the electroosmotic flow as well as inducing changes in analyte electrophoretic mobility, separation selectivity, and resolution. Changes in electrophoretic mobility by as much as 25% were observed for the sulfate anion, and the resolution of fluoride and phosphate was enhanced by a factor of 7.8. In the presence of 0.05-0.17% w/v poly(1,1-dimethyl-3,5-dimethylenepyrrolidinium) chromate at pH 8, separation currents were found to increase only slightly as compared to an electrolyte containing equivalent amounts of sodium chromate. Electroosmotic flow was also found to be fairly constant (+/- 16%) in the pH range 6.55-10.02 for 0.01% (w/v) poly(1,1-dimethyl-3,5-dimethylenepiperidinium) chromate at an ionic strength of 0.04, compared to a 400% change in the absence of the polyelectrolyte. The reproducibility of the electroosmotic mobility was between 0.36 and 6% RSD, and analyte electrophoretic mobility was between 0.01 and 1.6% RSD. Peak height reproducibility was 0.2-8.0% RSD. Separation efficiencies were between 258,000 and 780,000 theoretical plates, and detection limits were between 4.4 x 10(-7) and 9.1 x 10(-6) mol/L.","Cationic polymers for selectivity control in the capillary electrophoretic separation of inorganic anions Abs: The capillary electrophoretic (CE) separation of the inorganic anions bromide, chloride, nitrate, nitrite, fluoride, sulfate and phosphate is described in 0.005 mol/L sodium chromate electrolyte in the presence of soluble polydisperse ionic polymers (polyelectrolytes). The cationic polyelectrolytes used were as follows: poly(1,1-dimethyl-3,5-dimethylenepiperidinium) chromate, hexadimethrine chromate, poly(1,1-dimethyl-3,5-dimethylenepyrrolidinium) chromate and ((diethylamino)ethyl)-dextran chromate in the concentration range 0.004-0.6% (w/v). These polyelectrolytes were shown to be capable of reversing the direction of the electroosmotic flow as well as inducing changes in analyte electrophoretic mobility, separation selectivity, and resolution. Changes in electrophoretic mobility by as much as 25% were observed for the sulfate anion, and the resolution of fluoride and phosphate was enhanced by a factor of 7.8. In the presence of 0.05-0.17% w/v poly(1,1-dimethyl-3,5-dimethylenepyrrolidinium) chromate at pH 8, separation currents were found to increase only slightly as compared to an electrolyte containing equivalent amounts of sodium chromate. Electroosmotic flow was also found to be fairly constant (+/- 16%) in the pH range 6.55-10.02 for 0.01% (w/v) poly(1,1-dimethyl-3,5-dimethylenepiperidinium) chromate at an ionic strength of 0.04, compared to a 400% change in the absence of the polyelectrolyte. The reproducibility of the electroosmotic mobility was between 0.36 and 6% RSD, and analyte electrophoretic mobility was between 0.01 and 1.6% RSD. Peak height reproducibility was 0.2-8.0% RSD. Separation efficiencies were between 258,000 and 780,000 theoretical plates, and detection limits were between 4.4 x 10(-7) and 9.1 x 10(-6) mol/L."
1235687,Wixson et al. 1994,Reinfusion of postoperative wound drainage in total joint arthroplasty. Red blood cell survival and coagulopathy risk,"Fifty patients with total joint arthroplasties (28 total hip arthroplasties, 11 total knee arthroplasties, and 11 bilateral total knee arthroplasties) received autotransfusions from their postoperative wound drainage. The blood was collected in a closed sterile drainage system without any additional anticoagulant. Pre- and postoperative measurements were made of the patient's hemoglobin, platelets, fibrinogen, haptoglobin, fibrin degradation products, and D-dimer (a specific type of fibrin degradation product). Red blood cell survival was assessed in 16 of the patients by labeling the shed blood with 51Cr sodium chromate prior to reinfusion. To control for fluid shifts, continued bleeding, and dilution effects of further transfusions in the immediate postoperative period, 10 patients also had their native blood labeled with 111In oxime. In this study, the mean estimated blood loss was 1,062 mL (+/- 1,247) with a mean wound drainage of 836 mL (+/- 338). Of this, a mean of 450 mL (+/- 261) of blood was was given back to the patient in addition to routine, preoperative autologous donated blood. Six (12%) patients experienced transient fevers at the time of retransfusion. Detailed hematologic studies were performed on the shed blood in 19 patients. The collected blood was completely defibrinated, but did contain fibrin degradation products, as indicated by the D-dimer level, and hemolyzed blood as the haptoglobin was reduced. Even though the blood containing the above breakdown products was reinfused to the patients, there were no clinical manifestations of disseminated intravascular coagulation. Both the hemolyzed and defibrinated products were subsequently cleared by the body.(ABSTRACT TRUNCATED AT 250 WORDS)","Reinfusion of postoperative wound drainage in total joint arthroplasty. Red blood cell survival and coagulopathy risk Abs: Fifty patients with total joint arthroplasties (28 total hip arthroplasties, 11 total knee arthroplasties, and 11 bilateral total knee arthroplasties) received autotransfusions from their postoperative wound drainage. The blood was collected in a closed sterile drainage system without any additional anticoagulant. Pre- and postoperative measurements were made of the patient's hemoglobin, platelets, fibrinogen, haptoglobin, fibrin degradation products, and D-dimer (a specific type of fibrin degradation product). Red blood cell survival was assessed in 16 of the patients by labeling the shed blood with 51Cr sodium chromate prior to reinfusion. To control for fluid shifts, continued bleeding, and dilution effects of further transfusions in the immediate postoperative period, 10 patients also had their native blood labeled with 111In oxime. In this study, the mean estimated blood loss was 1,062 mL (+/- 1,247) with a mean wound drainage of 836 mL (+/- 338). Of this, a mean of 450 mL (+/- 261) of blood was was given back to the patient in addition to routine, preoperative autologous donated blood. Six (12%) patients experienced transient fevers at the time of retransfusion. Detailed hematologic studies were performed on the shed blood in 19 patients. The collected blood was completely defibrinated, but did contain fibrin degradation products, as indicated by the D-dimer level, and hemolyzed blood as the haptoglobin was reduced. Even though the blood containing the above breakdown products was reinfused to the patients, there were no clinical manifestations of disseminated intravascular coagulation. Both the hemolyzed and defibrinated products were subsequently cleared by the body.(ABSTRACT TRUNCATED AT 250 WORDS)"
1235686,Shi and  Dalal 1994,Generation of hydroxyl radical by chromate in biologically relevant systems: role of Cr(V) complexes versus tetraperoxochromate(V),"While Cr(V) species and .OH radicals have been suggested to play significant roles in the mechanism of chromate-related carcinogenesis, controversy still exists regarding the identity of the Cr(V) species and their role in the generation of .OH radicals. Some recent studies have suggested that the primary Cr(V) species involved is the tetraperoxochromate(V) (CrO8(3-)) ion, which produces .OH radical either on decomposition or by reaction with H2O2. The present study utilized ESR and spin trapping techniques to probe this mechanism. The results obtained show that (i) CrO8(3-) is not formed in any significant quantity in the reaction of chromate with biologically relevant reductants such as glutathione, glutathione reductase, NAD(P)H, ascorbate, vitamin B2, etc. (ii) Decomposition of CrO8(3-), or its reaction with H2O2 does not generate any significant amount of .OH radicals. (iii) The major Cr(V) species formed are complexes of Cr(V) with reductant moieties as ligands. (iv) These Cr(V) complexes generate .OH radicals from H2O2 via Fenton-like reaction. The present study thus disagrees with the recently proposed &quot;tetraperoxochromate(V) theory of carcinogenesis from chromate.&quot; Instead, it suggests an alternative mechanism, which might be labeled as &quot;the Cr(V)-complexation-Fenton reaction model of carcinogenesis from chromate.","Generation of hydroxyl radical by chromate in biologically relevant systems: role of Cr(V) complexes versus tetraperoxochromate(V) Abs: While Cr(V) species and .OH radicals have been suggested to play significant roles in the mechanism of chromate-related carcinogenesis, controversy still exists regarding the identity of the Cr(V) species and their role in the generation of .OH radicals. Some recent studies have suggested that the primary Cr(V) species involved is the tetraperoxochromate(V) (CrO8(3-)) ion, which produces .OH radical either on decomposition or by reaction with H2O2. The present study utilized ESR and spin trapping techniques to probe this mechanism. The results obtained show that (i) CrO8(3-) is not formed in any significant quantity in the reaction of chromate with biologically relevant reductants such as glutathione, glutathione reductase, NAD(P)H, ascorbate, vitamin B2, etc. (ii) Decomposition of CrO8(3-), or its reaction with H2O2 does not generate any significant amount of .OH radicals. (iii) The major Cr(V) species formed are complexes of Cr(V) with reductant moieties as ligands. (iv) These Cr(V) complexes generate .OH radicals from H2O2 via Fenton-like reaction. The present study thus disagrees with the recently proposed &quot;tetraperoxochromate(V) theory of carcinogenesis from chromate.&quot; Instead, it suggests an alternative mechanism, which might be labeled as &quot;the Cr(V)-complexation-Fenton reaction model of carcinogenesis from chromate."
1235685,Kortenkamp and  O'Brien 1994,The generation of DNA single-strand breaks during the reduction of chromate by ascorbic acid and/or glutathione in vitro,"The potential role of iron and copper and the involvement of hydroxyl radicals in the DNA cleavage caused by chromate and glutathione (GSH) has been investigated. We have also studied the ability of chromate, on reaction with ascorbate as well as in mixed solutions of ascorbate and GSH, to cause DNA strand breaks. In both fully demetalated and conventional (i.e., metal contaminated) systems, chromate and GSH induced similar numbers of DNA strand breaks. This observation suggests that traces of iron or copper contaminating the reaction mixtures do not play a major role in the DNA cleavage caused by chromate and GSH. A series of hydroxyl radical scavengers exhibited a protective influence on the induction of DNA strand breaks. However, glucose and sucrose, both strong hydroxyl radical scavengers, showed no concentration-dependent inhibition of DNA cleavage. Competition kinetics studies yielded apparent rate constants that were not consistent with hydroxyl radicals being the species responsible for DNA strand breaks. Ascorbate in combination with chromate was also found to induce strand breaks in DNA; this damage could be attributed to reactive intermediates generated during the reduction. When mixed systems of ascorbate and GSH in the presence of chromate were investigated, there were clearly interactions between the two reductants.","The generation of DNA single-strand breaks during the reduction of chromate by ascorbic acid and/or glutathione in vitro Abs: The potential role of iron and copper and the involvement of hydroxyl radicals in the DNA cleavage caused by chromate and glutathione (GSH) has been investigated. We have also studied the ability of chromate, on reaction with ascorbate as well as in mixed solutions of ascorbate and GSH, to cause DNA strand breaks. In both fully demetalated and conventional (i.e., metal contaminated) systems, chromate and GSH induced similar numbers of DNA strand breaks. This observation suggests that traces of iron or copper contaminating the reaction mixtures do not play a major role in the DNA cleavage caused by chromate and GSH. A series of hydroxyl radical scavengers exhibited a protective influence on the induction of DNA strand breaks. However, glucose and sucrose, both strong hydroxyl radical scavengers, showed no concentration-dependent inhibition of DNA cleavage. Competition kinetics studies yielded apparent rate constants that were not consistent with hydroxyl radicals being the species responsible for DNA strand breaks. Ascorbate in combination with chromate was also found to induce strand breaks in DNA; this damage could be attributed to reactive intermediates generated during the reduction. When mixed systems of ascorbate and GSH in the presence of chromate were investigated, there were clearly interactions between the two reductants."
1235683,Voitkun et al. 1994,Complexing of amino acids to DNA by chromate in intact cells,"Using o-pthaldialdehyde (OPT) fluorescence, the amino acids associated with DNA were studied following exposure of intact Chinese hamster ovary cells to chromate. Rigorous extraction with EDTA, acid, or base was required to release the amino acids cross-linked to the DNA isolated from control or chromate-treated cells by standard procedures (i.e., proteinase K, phenol, etc.). Amino acids resisting extraction from DNA were not studied since analysis was limited to those that could be released by these procedures. There was a chromate dose-dependent increase in amino acids complexed with the DNA that could be released by EDTA, acid, and base, and these amino acids were separated by HPLC and identified. Substantial increases in cysteine, glutamine, glutamic acid, histidine, threonine, and tyrosine were found as a function of increasing concentrations of chromate. There was also a time-dependent increase in complexing of these amino acids to the DNA by chromate. The amino acids found complexed to DNA in intact cells by chromate were thought to originate from reactions of free amino acids or small peptides with the DNA rather than being proteolytic products derived from larger proteins that were cross-linked to the DNA. This was supported by a number of experiments: a) free amino acids or bovine serum albumin (BSA) were cross-linked by chromium to DNA in vitro and the DNA was isolated by standard procedures.(ABSTRACT TRUNCATED AT 250 WORDS)","Complexing of amino acids to DNA by chromate in intact cells Abs: Using o-pthaldialdehyde (OPT) fluorescence, the amino acids associated with DNA were studied following exposure of intact Chinese hamster ovary cells to chromate. Rigorous extraction with EDTA, acid, or base was required to release the amino acids cross-linked to the DNA isolated from control or chromate-treated cells by standard procedures (i.e., proteinase K, phenol, etc.). Amino acids resisting extraction from DNA were not studied since analysis was limited to those that could be released by these procedures. There was a chromate dose-dependent increase in amino acids complexed with the DNA that could be released by EDTA, acid, and base, and these amino acids were separated by HPLC and identified. Substantial increases in cysteine, glutamine, glutamic acid, histidine, threonine, and tyrosine were found as a function of increasing concentrations of chromate. There was also a time-dependent increase in complexing of these amino acids to the DNA by chromate. The amino acids found complexed to DNA in intact cells by chromate were thought to originate from reactions of free amino acids or small peptides with the DNA rather than being proteolytic products derived from larger proteins that were cross-linked to the DNA. This was supported by a number of experiments: a) free amino acids or bovine serum albumin (BSA) were cross-linked by chromium to DNA in vitro and the DNA was isolated by standard procedures.(ABSTRACT TRUNCATED AT 250 WORDS)"
1235681,Tsuzuki et al. 1994,"DNA single-strand breaks and cytotoxicity induced by chromate(VI), cadmium(II), and mercury(II) in hydrogen peroxide-resistant cell lines","The induction of cytotoxicity and DNA single-strand breaks by chromium(VI), cadmium(II), and mercury(II) were compared in H2O2-resistant Chinese hamster ovary (CHO(R)) cells and parental (CHO(P)) cells. Using a colony-forming assay, CHO(R) cells were found to be significantly more resistant than CHO(P) cells to the cytotoxicity caused by CdCl2 and HgCl2, but not to that caused by Na2CrO4. However, the DNA single-strand breaks produced by each of these metals were significantly lower in the CHO(R) cells. With respect to chromium reduction, the level of chromium(V) in CHO(R) cells was decreased. The role of intracellular active oxygen in the heavy metal-induced DNA damage and cytotoxicity is discussed.","DNA single-strand breaks and cytotoxicity induced by chromate(VI), cadmium(II), and mercury(II) in hydrogen peroxide-resistant cell lines Abs: The induction of cytotoxicity and DNA single-strand breaks by chromium(VI), cadmium(II), and mercury(II) were compared in H2O2-resistant Chinese hamster ovary (CHO(R)) cells and parental (CHO(P)) cells. Using a colony-forming assay, CHO(R) cells were found to be significantly more resistant than CHO(P) cells to the cytotoxicity caused by CdCl2 and HgCl2, but not to that caused by Na2CrO4. However, the DNA single-strand breaks produced by each of these metals were significantly lower in the CHO(R) cells. With respect to chromium reduction, the level of chromium(V) in CHO(R) cells was decreased. The role of intracellular active oxygen in the heavy metal-induced DNA damage and cytotoxicity is discussed."
1235678,Liu et al. 1994,Low-frequency EPR detection of chromium(V) formation by chromium(VI) reduction in whole live mice,"Measurements by direct low frequency EPR spectroscopy provide the first evidence that Cr(V) is generated in one-electron reduction of Cr(VI) in live mice. The Cr(V) yield reached a maximum about 10 min following Cr(VI) intravenous injection and then decayed slowly with a life time of approximately 37 min. The time for the Cr(V) EPR signal to reach maximum intensity increased with the dose of Cr(VI). A discernible EPR signal was still observable at a dose as low as 0.1 mmol/kg. The Cr(V) was found predominantly in the liver, with a small amount in the blood. No Cr(V) signal was detectable in heart, spleen, kidney, and lung. Pretreatment of the animals with metal ion chelators, ethylenediaminetetraacetic acid, diethylenetriaminepentaacetic acid, and 1,10-phenanthroline significantly reduced the intensity of the Cr(V) signal that was observed.","Low-frequency EPR detection of chromium(V) formation by chromium(VI) reduction in whole live mice Abs: Measurements by direct low frequency EPR spectroscopy provide the first evidence that Cr(V) is generated in one-electron reduction of Cr(VI) in live mice. The Cr(V) yield reached a maximum about 10 min following Cr(VI) intravenous injection and then decayed slowly with a life time of approximately 37 min. The time for the Cr(V) EPR signal to reach maximum intensity increased with the dose of Cr(VI). A discernible EPR signal was still observable at a dose as low as 0.1 mmol/kg. The Cr(V) was found predominantly in the liver, with a small amount in the blood. No Cr(V) signal was detectable in heart, spleen, kidney, and lung. Pretreatment of the animals with metal ion chelators, ethylenediaminetetraacetic acid, diethylenetriaminepentaacetic acid, and 1,10-phenanthroline significantly reduced the intensity of the Cr(V) signal that was observed."
1235674,Natochin et al. 1994,Renal failure and nephrotoxic drug-induced disturbances in rat kidney tissue,"The injection to rats of glycerol, cisplatin, uranyl acetate, sodium dichromate, and mercuric chloride is followed on the third day by acute renal failure. A new approach for quantitative estimation of disturbance of excretory renal function is presented. The decrease in renal function due to uranyl acetate was 77%; sodium dichromate, 71%; mercuric chloride, 52%; cisplatin, 25%; and glycerol, 10%. The kidneys still maintained serum ion concentration close to normal values. Injection of nephrotoxic drugs increased kidney wet weight by 24-57%. This was caused by swelling of renal tissue and increases in dry weight of the kidneys. The sodium content increased in the renal cortex and decreased in the papilla. The potassium content of the renal cortex is increased. The effect of some nephrotoxic drugs is suggested to depend on an increased number of cells in the renal cortex (probably due to hemostasis and inflammation) and a decrease of renal medulla function. The above drugs induce disturbance of kidney tissue but have no effect on the ion and water content in liver and m. gastrocnemius.","Renal failure and nephrotoxic drug-induced disturbances in rat kidney tissue Abs: The injection to rats of glycerol, cisplatin, uranyl acetate, sodium dichromate, and mercuric chloride is followed on the third day by acute renal failure. A new approach for quantitative estimation of disturbance of excretory renal function is presented. The decrease in renal function due to uranyl acetate was 77%; sodium dichromate, 71%; mercuric chloride, 52%; cisplatin, 25%; and glycerol, 10%. The kidneys still maintained serum ion concentration close to normal values. Injection of nephrotoxic drugs increased kidney wet weight by 24-57%. This was caused by swelling of renal tissue and increases in dry weight of the kidneys. The sodium content increased in the renal cortex and decreased in the papilla. The potassium content of the renal cortex is increased. The effect of some nephrotoxic drugs is suggested to depend on an increased number of cells in the renal cortex (probably due to hemostasis and inflammation) and a decrease of renal medulla function. The above drugs induce disturbance of kidney tissue but have no effect on the ion and water content in liver and m. gastrocnemius."
1235669,Liu et al. 1995,Low-frequency EPR study of chromium(V) formation from chromium(VI) in living plants,"The reduction of Cr(VI) by green algae and higher plants was investigated using a low-frequency EPR spectrometer equipped with an extended loop gap resonator. Incubation of algae (Spirogyra and Mougeotia) with Cr(VI) generated both Cr(V) and Cr(III). The maximum Cr(V) signal was observed in about 10 minutes. Incubation of Cr(VI) with oat, soybean, and garlic generated Cr(V). The maximum Cr(V) peak appeared after more than 10 hours of incubation, and Cr(V) was located predominantly in the roots. The Cr(V) peak exhibited hyperfine splittings of about 0.79 gauss, typical of the Cr(V) complexes with diol-containing molecules. The results suggest that the reduction of Cr(VI) to lower oxidation states by living plants may provide a detoxification pathway for Cr(VI) in ecological systems. The results also indicate that low-frequency EPR may be used to investigate the metabolism of paramagnetic metal ions in intact plants.","Low-frequency EPR study of chromium(V) formation from chromium(VI) in living plants Abs: The reduction of Cr(VI) by green algae and higher plants was investigated using a low-frequency EPR spectrometer equipped with an extended loop gap resonator. Incubation of algae (Spirogyra and Mougeotia) with Cr(VI) generated both Cr(V) and Cr(III). The maximum Cr(V) signal was observed in about 10 minutes. Incubation of Cr(VI) with oat, soybean, and garlic generated Cr(V). The maximum Cr(V) peak appeared after more than 10 hours of incubation, and Cr(V) was located predominantly in the roots. The Cr(V) peak exhibited hyperfine splittings of about 0.79 gauss, typical of the Cr(V) complexes with diol-containing molecules. The results suggest that the reduction of Cr(VI) to lower oxidation states by living plants may provide a detoxification pathway for Cr(VI) in ecological systems. The results also indicate that low-frequency EPR may be used to investigate the metabolism of paramagnetic metal ions in intact plants."
1235668,Bagchi et al. 1995,"Chromium-induced excretion of urinary lipid metabolites, DNA damage, nitric oxide production, and generation of reactive oxygen species in Sprague-Dawley rats","Chromium and its salts induce cytotoxicity and mutagenesis, and vitamin E has been reported to attenuate chromate-induced cytotoxicity. These observations suggest that chromium produces reactive oxygen species which may mediate many of the untoward effects of chromium. We have therefore examined and compared the effects of Cr(III) (chromium chloride hexahydrate) and Cr(VI) (sodium dichromate) following single oral doses (0.50 LD50) on the production of reactive oxygen species by peritoneal macrophages, and hepatic mitochondria and microsomes in rats. The effects of Cr(III) and Cr(VI) on hepatic mitochondrial and microsomal lipid peroxidation and enhanced excretion of urinary lipid metabolites as well as the incidence of hepatic nuclear DNA damage and nitric oxide (NO) production were also examined. Increases in lipid peroxidation of 1.8- and 2.2-fold occurred in hepatic mitochondria and microsomes, respectively, 48 hr after the oral administration of 25 mg Cr(VI)/kg, while increases of 1.2- and 1.4-fold, respectively, were observed after 895 mg Cr(III)/kg. The urinary excretion of malondialdehyde (MDA), formaldehyde (FA), acetaldehyde (ACT) and acetone (ACON) were determined at 0-96 hr after Cr administration. Between 48 and 72 hr post-treatment, maximal excretion of the four urinary lipid metabolites was observed with increases of 1.5- to 5.4-fold in Cr(VI) treated rats. Peritoneal macrophages from Cr(VI) treated animals 48 hr after treatment resulted in 1.4- and 3.6-fold increases in chemiluminescence and iodonitrotetrazolium reduction, indicating enhanced production of superoxide anion, while macrophages from Cr(III) treated animals showed negligible increases. Increases in DNA single strand breaks of 1.7-fold and 1.5-fold were observed following administration of Cr(VI) and Cr(III), respectively, at 48 hr post-treatment. Enhanced production of NO by peritoneal exudate cells (primarily macrophages) was monitored following Cr(VI) administration at both 24 and 48 hr post-treatment with enhanced production of NO being observed at both timepoints. The results indicate that both Cr(VI) and Cr(III) induce an oxidative stress at equitoxic doses, while Cr(VI) induces greater oxidative stress in rats as compared with Cr(III) treated animals.","Chromium-induced excretion of urinary lipid metabolites, DNA damage, nitric oxide production, and generation of reactive oxygen species in Sprague-Dawley rats Abs: Chromium and its salts induce cytotoxicity and mutagenesis, and vitamin E has been reported to attenuate chromate-induced cytotoxicity. These observations suggest that chromium produces reactive oxygen species which may mediate many of the untoward effects of chromium. We have therefore examined and compared the effects of Cr(III) (chromium chloride hexahydrate) and Cr(VI) (sodium dichromate) following single oral doses (0.50 LD50) on the production of reactive oxygen species by peritoneal macrophages, and hepatic mitochondria and microsomes in rats. The effects of Cr(III) and Cr(VI) on hepatic mitochondrial and microsomal lipid peroxidation and enhanced excretion of urinary lipid metabolites as well as the incidence of hepatic nuclear DNA damage and nitric oxide (NO) production were also examined. Increases in lipid peroxidation of 1.8- and 2.2-fold occurred in hepatic mitochondria and microsomes, respectively, 48 hr after the oral administration of 25 mg Cr(VI)/kg, while increases of 1.2- and 1.4-fold, respectively, were observed after 895 mg Cr(III)/kg. The urinary excretion of malondialdehyde (MDA), formaldehyde (FA), acetaldehyde (ACT) and acetone (ACON) were determined at 0-96 hr after Cr administration. Between 48 and 72 hr post-treatment, maximal excretion of the four urinary lipid metabolites was observed with increases of 1.5- to 5.4-fold in Cr(VI) treated rats. Peritoneal macrophages from Cr(VI) treated animals 48 hr after treatment resulted in 1.4- and 3.6-fold increases in chemiluminescence and iodonitrotetrazolium reduction, indicating enhanced production of superoxide anion, while macrophages from Cr(III) treated animals showed negligible increases. Increases in DNA single strand breaks of 1.7-fold and 1.5-fold were observed following administration of Cr(VI) and Cr(III), respectively, at 48 hr post-treatment. Enhanced production of NO by peritoneal exudate cells (primarily macrophages) was monitored following Cr(VI) administration at both 24 and 48 hr post-treatment with enhanced production of NO being observed at both timepoints. The results indicate that both Cr(VI) and Cr(III) induce an oxidative stress at equitoxic doses, while Cr(VI) induces greater oxidative stress in rats as compared with Cr(III) treated animals."
1235667,de Azevedo et al. 1995,Renin-aldosterone axis in normoalbuminuric insulin-dependent diabetes mellitus patients with glomerular hyperfiltration,"The renin-aldosterone axis was evaluated by captopril test in 22 normotensive normoalbuminuric insulin-dependent diabetes mellitus (IDDM) patients with and without glomerular hyperfiltration. Patients were divided into those with glomerular hyperfiltration (Hf-IDDM) and with normal glomerular filtration rate (GFR; Nf-IDDM) according to the upper limit of GFR (134.7 ml/min per 1.73 m2). Sixteen normal individuals were also studied. GFR was measured by the 51Cr-EDTA single injection method, extracellular fluid volume as the distribution volume of 51Cr-EDTA, and blood volume using 51Cr-sodium chromate-labelled red blood cells. Twenty-five mg of captopril were administered per os and plasma renin activity (PRA; RIA), plasma aldosterone (RIA) and blood pressure were measured at 0 and 120 min post-captopril. PRA at time zero (Hf-IDDM = 2.4 +/- 1.7; Nf-IDDM = 2.5 +/- 1.9; controls = 1.0 +/- 0.6 ng/ml/h) and at 120 min (Hf-IDDM = 9.9 +/- 8.3; Nf-IDDM = 11.2 +/- 8.9; controls = 5.4 +/- 5.7 ng/ml/h) was higher in IDDM patients than in controls (P = 0.01). The increase of PRA was similar in patients (Hf-IDDM = 7.5 +/- 7.3, and Nf-IDDM = 8.7 +/- 7.2 ng/ml/h) and controls (4.4 +/- 5.3 ng/ml/h). There was no difference in PRA levels between Hf-IDDM and Nf-IDDM patients. PRA did not correlate with GFR, aldosterone, blood pressure, blood volume, duration of diabetes, 24-h urinary sodium and metabolic control indexes. Plasma aldosterone and the magnitude of its decrease after captopril was similar among patients and controls.(ABSTRACT TRUNCATED AT 250 WORDS)","Renin-aldosterone axis in normoalbuminuric insulin-dependent diabetes mellitus patients with glomerular hyperfiltration Abs: The renin-aldosterone axis was evaluated by captopril test in 22 normotensive normoalbuminuric insulin-dependent diabetes mellitus (IDDM) patients with and without glomerular hyperfiltration. Patients were divided into those with glomerular hyperfiltration (Hf-IDDM) and with normal glomerular filtration rate (GFR; Nf-IDDM) according to the upper limit of GFR (134.7 ml/min per 1.73 m2). Sixteen normal individuals were also studied. GFR was measured by the 51Cr-EDTA single injection method, extracellular fluid volume as the distribution volume of 51Cr-EDTA, and blood volume using 51Cr-sodium chromate-labelled red blood cells. Twenty-five mg of captopril were administered per os and plasma renin activity (PRA; RIA), plasma aldosterone (RIA) and blood pressure were measured at 0 and 120 min post-captopril. PRA at time zero (Hf-IDDM = 2.4 +/- 1.7; Nf-IDDM = 2.5 +/- 1.9; controls = 1.0 +/- 0.6 ng/ml/h) and at 120 min (Hf-IDDM = 9.9 +/- 8.3; Nf-IDDM = 11.2 +/- 8.9; controls = 5.4 +/- 5.7 ng/ml/h) was higher in IDDM patients than in controls (P = 0.01). The increase of PRA was similar in patients (Hf-IDDM = 7.5 +/- 7.3, and Nf-IDDM = 8.7 +/- 7.2 ng/ml/h) and controls (4.4 +/- 5.3 ng/ml/h). There was no difference in PRA levels between Hf-IDDM and Nf-IDDM patients. PRA did not correlate with GFR, aldosterone, blood pressure, blood volume, duration of diabetes, 24-h urinary sodium and metabolic control indexes. Plasma aldosterone and the magnitude of its decrease after captopril was similar among patients and controls.(ABSTRACT TRUNCATED AT 250 WORDS)"
1235665,Goto and  Kida 1995,Insulin-like action of chromate on glucose transport in isolated rat adipocytes,"The effects of chromium compounds on 3-O-methylglucose (3-O-MG) transport were studied in isolated rat adipocytes. Sodium chromate significantly stimulated 3-O-MG uptake into adipocytes in a dose-dependent manner without altering the equilibrium space of 3-O-MG in adipocytes. The stimulatory effect reached the maximum at 300 microM, and the effect was 60-70% of the maximal insulin effect that was obtained with 20 nM insulin. The chromate concentration achieving a half-maximal effect was estimated at 50 microM. The effect of the combination of 1 mM chromate and 20 nM insulin was equipotent to that of 20 nM insulin alone, which showed that these two effects were not additive. The stimulatory effects of 1 mM chromate and 20 nM insulin were entirely abolished in adipocytes deprived of ATP, which indicated that these effects were completely ATP-dependent. Judging from experiments using various chromium compounds, CrO4(2-) was responsible for the insulinomimetic action. These results indicate that the action of CrO4(2-) is exerted through a mechanism analogous to that of insulin action, and that CrO4(2-) is a novel and useful tool for studying issues involved in insulin actions.","Insulin-like action of chromate on glucose transport in isolated rat adipocytes Abs: The effects of chromium compounds on 3-O-methylglucose (3-O-MG) transport were studied in isolated rat adipocytes. Sodium chromate significantly stimulated 3-O-MG uptake into adipocytes in a dose-dependent manner without altering the equilibrium space of 3-O-MG in adipocytes. The stimulatory effect reached the maximum at 300 microM, and the effect was 60-70% of the maximal insulin effect that was obtained with 20 nM insulin. The chromate concentration achieving a half-maximal effect was estimated at 50 microM. The effect of the combination of 1 mM chromate and 20 nM insulin was equipotent to that of 20 nM insulin alone, which showed that these two effects were not additive. The stimulatory effects of 1 mM chromate and 20 nM insulin were entirely abolished in adipocytes deprived of ATP, which indicated that these effects were completely ATP-dependent. Judging from experiments using various chromium compounds, CrO4(2-) was responsible for the insulinomimetic action. These results indicate that the action of CrO4(2-) is exerted through a mechanism analogous to that of insulin action, and that CrO4(2-) is a novel and useful tool for studying issues involved in insulin actions."
1235664,Casadevall and  Kortenkamp 1995,The formation of both apurinic/apyrimidinic sites and single-strand breaks by chromate and glutathione arises from attack by the same single reactive species and is dependent on molecular oxygen,"The induction of apurinic/apyrimidinic sites (AP sites) and DNA single-strand breaks (SSB) by chromate and glutathione in isolated DNA was investigated using agents that cleave the DNA at AP sites (putrescine and exonuclease III). It was found that chromate/glutathione-induced AP sites contain free aldehyde groups, as cleavage by putrescine could be prevented by treatment with sodium borohydride. The formation of AP sites and SSB followed a very similar temporal pattern, suggesting that both lesions arise from attack by the same single reactive species deriving from chromate and glutathione. Furthermore, the induction of both lesions was found to be dependent on the presence of molecular oxygen.","The formation of both apurinic/apyrimidinic sites and single-strand breaks by chromate and glutathione arises from attack by the same single reactive species and is dependent on molecular oxygen Abs: The induction of apurinic/apyrimidinic sites (AP sites) and DNA single-strand breaks (SSB) by chromate and glutathione in isolated DNA was investigated using agents that cleave the DNA at AP sites (putrescine and exonuclease III). It was found that chromate/glutathione-induced AP sites contain free aldehyde groups, as cleavage by putrescine could be prevented by treatment with sodium borohydride. The formation of AP sites and SSB followed a very similar temporal pattern, suggesting that both lesions arise from attack by the same single reactive species deriving from chromate and glutathione. Furthermore, the induction of both lesions was found to be dependent on the presence of molecular oxygen."
1235663,Ueno et al. 1995,Effect of dimethylthiourea on chromium (VI)-induced DNA single-strand breaks in Chinese hamster V-79 cells,"The effect of 1,3-dimethyl-2-thiourea (DMTU), a specific hydroxyl radical scavenger on chromate-induced DNA breaks, was studied using Chinese hamster V-79 cells. Incubation of cells with Na2CrO4 plus DMTU resulted in a small but significant decrease in cellular levels of the metal-caused DNA single-strand breaks. Electron spin resonance studies showed that DMTU did not affect the formation of chromium (V) complexes either in cells or in the reaction of Na2CrO4 with reduced glutathione in vitro, however, DMTU suppressed the generation of hydroxyl radicals in the reaction of hydrogen peroxide and chromium (V) in vitro. Thus, Na2CrO4-induced DNA breaks were inhibited by DMTU, possibly due to its ability to scavenge hydroxyl radicals. These and other previous studies indicated that the formation of hydroxyl radicals contribute to the induction of DNA breaks by Na2CrO4 in intact cells, but presumably is not the only mechanism involved.","Effect of dimethylthiourea on chromium (VI)-induced DNA single-strand breaks in Chinese hamster V-79 cells Abs: The effect of 1,3-dimethyl-2-thiourea (DMTU), a specific hydroxyl radical scavenger on chromate-induced DNA breaks, was studied using Chinese hamster V-79 cells. Incubation of cells with Na2CrO4 plus DMTU resulted in a small but significant decrease in cellular levels of the metal-caused DNA single-strand breaks. Electron spin resonance studies showed that DMTU did not affect the formation of chromium (V) complexes either in cells or in the reaction of Na2CrO4 with reduced glutathione in vitro, however, DMTU suppressed the generation of hydroxyl radicals in the reaction of hydrogen peroxide and chromium (V) in vitro. Thus, Na2CrO4-induced DNA breaks were inhibited by DMTU, possibly due to its ability to scavenge hydroxyl radicals. These and other previous studies indicated that the formation of hydroxyl radicals contribute to the induction of DNA breaks by Na2CrO4 in intact cells, but presumably is not the only mechanism involved."
1235659,Bonnafous et al. 1995,Benzodiazepine-withdrawal-induced gastric emptying disturbances in rats: evidence for serotonin receptor involvement,"This study was performed in rats to determine if serotonin and its receptors are involved in the increase of gastric emptying (GE) induced by benzodiazepine (BZ) withdrawal. GE was measured with a test meal (2 ml) containing 1 microCi/ml of 51Cr sodium chromate administered in rats, either previously receiving injections with diazepam (15 mg/kg/day i.p.) or with DMSO (0.9 ml/day i.p.) during 7 days. On the 8th day, animals received the different serotonin (5-HT) agonists or antagonists, and flumazenil (BZ antagonist; 15 mg/kg i.p.) 30 and 15 min, respectively, before the test meal. Methiotepin (5-HT1 antagonist) either i.p. (0.1-1 mg/kg) or intracerebroventricularly (10 micrograms/kg) had no effect on the increase of GE induced by precipitated-withdrawal. 8-OH-DPAT (5-HT1A agonist) administered i.c.v. (1-10 micrograms/kg) dose dependently reduced GE increase. Administered i.p. (0.1 mg/kg), it blocked GE increase in control and diazepam-withdrawn rats. Ritanserin (5-HT2 antagonist) antagonized GE increase only when administered i.p. (0.1 mg/kg). Granisetron (5-HT3 antagonist) was active both i.p. (0.01-0.1 mg/kg) and intracerebroventricularly (1-10 micrograms/kg). Administered intracerebroventricularly (1 microgram/kg) in diazepam-treated rats, 5-HTP mimicked the effect of flumazenil. It is concluded that diazepam-withdrawal increases GE by stimulating central release of 5-HT and/or central activation of 5-HT neurons. At least central 5-HT3 receptors, and in less extend, peripheral 5-HT2 receptors are involved in this mechanism.","Benzodiazepine-withdrawal-induced gastric emptying disturbances in rats: evidence for serotonin receptor involvement Abs: This study was performed in rats to determine if serotonin and its receptors are involved in the increase of gastric emptying (GE) induced by benzodiazepine (BZ) withdrawal. GE was measured with a test meal (2 ml) containing 1 microCi/ml of 51Cr sodium chromate administered in rats, either previously receiving injections with diazepam (15 mg/kg/day i.p.) or with DMSO (0.9 ml/day i.p.) during 7 days. On the 8th day, animals received the different serotonin (5-HT) agonists or antagonists, and flumazenil (BZ antagonist; 15 mg/kg i.p.) 30 and 15 min, respectively, before the test meal. Methiotepin (5-HT1 antagonist) either i.p. (0.1-1 mg/kg) or intracerebroventricularly (10 micrograms/kg) had no effect on the increase of GE induced by precipitated-withdrawal. 8-OH-DPAT (5-HT1A agonist) administered i.c.v. (1-10 micrograms/kg) dose dependently reduced GE increase. Administered i.p. (0.1 mg/kg), it blocked GE increase in control and diazepam-withdrawn rats. Ritanserin (5-HT2 antagonist) antagonized GE increase only when administered i.p. (0.1 mg/kg). Granisetron (5-HT3 antagonist) was active both i.p. (0.01-0.1 mg/kg) and intracerebroventricularly (1-10 micrograms/kg). Administered intracerebroventricularly (1 microgram/kg) in diazepam-treated rats, 5-HTP mimicked the effect of flumazenil. It is concluded that diazepam-withdrawal increases GE by stimulating central release of 5-HT and/or central activation of 5-HT neurons. At least central 5-HT3 receptors, and in less extend, peripheral 5-HT2 receptors are involved in this mechanism."
1235657,Kurosaki et al. 1995,Unusual findings in a fatal case of poisoning with chromate compounds,"An interesting case of acute poisoning by chromate compounds is reported. A 51-year-old man committed suicide by ingesting a fatal dose of sodium chromate solution. He unexpectedly lost consciousness 6 h after the ingestion and died approximately 20.5 h later. An examination of the blood showed noticeable hepatic damage and thrombocytopenia. The postmortem examination revealed extensive bleeding in the alimentary tract and a severe hepatic lesion due to hepatocellular necrosis. However, the renal disorder was unusually light in the microscopic and clinical findings. Moreover, the renal lesion was observed mainly in the distal tubules instead of the proximal tubules which is more typical in cases of acute poisonings by diverse heavy metals including chromium. The patient's death was assumed to have been caused by circulatory collapse due to internal bleeding and the direct toxicity of chromate compounds with hepatic malfunction and possibly disseminated intravascular coagulation (DIC).","Unusual findings in a fatal case of poisoning with chromate compounds Abs: An interesting case of acute poisoning by chromate compounds is reported. A 51-year-old man committed suicide by ingesting a fatal dose of sodium chromate solution. He unexpectedly lost consciousness 6 h after the ingestion and died approximately 20.5 h later. An examination of the blood showed noticeable hepatic damage and thrombocytopenia. The postmortem examination revealed extensive bleeding in the alimentary tract and a severe hepatic lesion due to hepatocellular necrosis. However, the renal disorder was unusually light in the microscopic and clinical findings. Moreover, the renal lesion was observed mainly in the distal tubules instead of the proximal tubules which is more typical in cases of acute poisonings by diverse heavy metals including chromium. The patient's death was assumed to have been caused by circulatory collapse due to internal bleeding and the direct toxicity of chromate compounds with hepatic malfunction and possibly disseminated intravascular coagulation (DIC)."
1235656,Miesel et al. 1995,Induction of arthritis in mice and rats by potassium peroxochromate and assessment of disease activity by whole blood chemiluminescence and 99mpertechnetate-imaging,"Arthritis develops in DBA/1xB10A(4R) mice and Wistar rats upon intraplantar injection of potassium peroxochromate (K3CrO8), and is here quantified by whole blood chemiluminescence (CL) and 99mpertechnetate-imaging (99mTcO4-), and related to overt disease symptoms (the arthritis index). During the aqueous decay of K3CrO8 to chromate (VI), the chromium(V)-bound oxygen is released as superoxide, hydroxyl radicals, singlet oxygen and hydrogen peroxide, the same reactants, which are produced by activated phagocytes during inflammation. Reactive oxygen species (ROS) trigger the breakdown of the sulfhydryl-dependent antioxidant defence system and induce the nuclear factor kappa B-dependent expression of pro-inflammatory cytokines, which prime phagocytic NADPH oxidases to the enhanced production of ROS. During both the acute inflammatory response and the onset of the secondary response in non-injected paws, the phorbolester-stimulated ROS production of phagocytes was significantly enhanced (p &lt; 0.001) and correlated well to the arthritis index (r = 0.797) and the uptake of 99mTcO4- into inflamed joints. Chromate(VI), formed during the decay of K3CrO8, contributes to the progression of arthritis by inhibition of glutathione reductase, thereby increasing intracellular H2O2 concentrations. In addition, Cr(VI) reduced to Cr(V) by ascorbate, catalyzes hydroxyl radical production in the presence of hydrogen peroxide. A stable loop forms, in which ROS, continuously produced by Cr(VI)/Cr(V) redox-cycling, drive the primary response into chronic self-perpetuating inflammation. We see the main application of K3CrO8-induced arthritis and its assessment by both 99mTcO4- imaging and chemiluminescent immunosensoring of phagocytic activity in unseparated blood as for the rapid screening of novel anti-rheumatic drugs and treatments.","Induction of arthritis in mice and rats by potassium peroxochromate and assessment of disease activity by whole blood chemiluminescence and 99mpertechnetate-imaging Abs: Arthritis develops in DBA/1xB10A(4R) mice and Wistar rats upon intraplantar injection of potassium peroxochromate (K3CrO8), and is here quantified by whole blood chemiluminescence (CL) and 99mpertechnetate-imaging (99mTcO4-), and related to overt disease symptoms (the arthritis index). During the aqueous decay of K3CrO8 to chromate (VI), the chromium(V)-bound oxygen is released as superoxide, hydroxyl radicals, singlet oxygen and hydrogen peroxide, the same reactants, which are produced by activated phagocytes during inflammation. Reactive oxygen species (ROS) trigger the breakdown of the sulfhydryl-dependent antioxidant defence system and induce the nuclear factor kappa B-dependent expression of pro-inflammatory cytokines, which prime phagocytic NADPH oxidases to the enhanced production of ROS. During both the acute inflammatory response and the onset of the secondary response in non-injected paws, the phorbolester-stimulated ROS production of phagocytes was significantly enhanced (p &lt; 0.001) and correlated well to the arthritis index (r = 0.797) and the uptake of 99mTcO4- into inflamed joints. Chromate(VI), formed during the decay of K3CrO8, contributes to the progression of arthritis by inhibition of glutathione reductase, thereby increasing intracellular H2O2 concentrations. In addition, Cr(VI) reduced to Cr(V) by ascorbate, catalyzes hydroxyl radical production in the presence of hydrogen peroxide. A stable loop forms, in which ROS, continuously produced by Cr(VI)/Cr(V) redox-cycling, drive the primary response into chronic self-perpetuating inflammation. We see the main application of K3CrO8-induced arthritis and its assessment by both 99mTcO4- imaging and chemiluminescent immunosensoring of phagocytic activity in unseparated blood as for the rapid screening of novel anti-rheumatic drugs and treatments."
1235654,Bean et al. 1995,Comparison of tetrazolium colorimetric and 51Cr release assays for cytotoxicity determination of dental biomaterials,"<strong>OBJECTIVES: </strong>The purpose of this study was to compare a methylthiazole tetrazolium (MTT) dye colorimetric method with the standard 51Cr assay as methods of assessing cytotoxicity of dental materials.<br /><br /><strong>METHODS: </strong>Two MTT-based colorimetric formats, test tube and 96-well microplate methods, were compared to the 51Cr release assay. A series of eight dental materials were evaluated. Cytotoxicity profiles were determined for each test material. A TC50 value (Toxic Concentration required to kill 50% of the cells) was determined for each biomaterial, and these results were used to make statistical comparisons between the methods.<br /><br /><strong>RESULTS: </strong>The three methods were statistically correlated (p&lt;0.005) by comparison of the eight samples tested. That is, the same rank in toxicity was given by the two tetrazolium sample formats and the 51Cr method.<br /><br /><strong>SIGNIFICANCE: </strong>The MTT assay was found to have several advantages in comparison to the current standard 51Cr release assay. Optimized in the 96-well format, complete dose response curves and greater sample comparisons can be made rapidly, making the MTT method more economical in time and cost. Furthermore, the MTT method is based on intracellular biochemical changes, measuring cell viability rather than cell morbidity, and has lower detectable limits than the 51Cr release method. There is also less detector chemical binding interference than encountered in the 51Cr release method.","Comparison of tetrazolium colorimetric and 51Cr release assays for cytotoxicity determination of dental biomaterials Abs: <strong>OBJECTIVES: </strong>The purpose of this study was to compare a methylthiazole tetrazolium (MTT) dye colorimetric method with the standard 51Cr assay as methods of assessing cytotoxicity of dental materials.<br /><br /><strong>METHODS: </strong>Two MTT-based colorimetric formats, test tube and 96-well microplate methods, were compared to the 51Cr release assay. A series of eight dental materials were evaluated. Cytotoxicity profiles were determined for each test material. A TC50 value (Toxic Concentration required to kill 50% of the cells) was determined for each biomaterial, and these results were used to make statistical comparisons between the methods.<br /><br /><strong>RESULTS: </strong>The three methods were statistically correlated (p&lt;0.005) by comparison of the eight samples tested. That is, the same rank in toxicity was given by the two tetrazolium sample formats and the 51Cr method.<br /><br /><strong>SIGNIFICANCE: </strong>The MTT assay was found to have several advantages in comparison to the current standard 51Cr release assay. Optimized in the 96-well format, complete dose response curves and greater sample comparisons can be made rapidly, making the MTT method more economical in time and cost. Furthermore, the MTT method is based on intracellular biochemical changes, measuring cell viability rather than cell morbidity, and has lower detectable limits than the 51Cr release method. There is also less detector chemical binding interference than encountered in the 51Cr release method."
1235653,Haddad et al. 1995,Respiration of amniotic fluid in near-term foetal rabbit,"<strong>OBJECTIVE: </strong>To examine the existence of amniotic fluid inhalation in foetal rabbit near term.<br /><br /><strong>STUDY DESIGN: </strong>Rabbit red cells labelled with 51 radio-chromium (Cr51-S1: Injectable solution sodium chromate, volumic activity: 74 MBq/ml; Cis-BioInternational, France) were injected into the amniotic sac of 24 New Zealand White foetal rabbits (mean gestation: 31 days) at day 25 per-laparotomy. At day 26, just prior to caesarean section, human serum albumin labelled with 125 radio-active iode (125I-HSA) (SERALB-125: human serum albumin labelled with radioactive Iode 125, volumic activity: 185 kBq/ml, Cis-BioInternational, France) was injected into each amniotic sac. The lungs, digestive tracts, kidneys and liver were excised separately and radioactivity counted in each organ.<br /><br /><strong>RESULTS: </strong>On day 26 of gestation, the 51Cr-RC radioactivity rate per gram of tissue in lungs, digestive tract amniotic fluid, liver and kidneys were respectively 1.66 +/- 2.8%, 1.15 +/- 1.6%, 0.015 +/- 0.02% and 0.04 +/- 0.07% of the total amount of radioactivity injected into the amniotic sac at day 25. The lungs' radioactivity was significantly higher than liver (t = 2.94, P &lt; 0.01) or kidneys radioactivity (t = 2.38, P &lt; 0.05). The 125I-HSA injected just prior to caesarean section at day 26 was not found in any foetal organ.<br /><br /><strong>CONCLUSIONS: </strong>Lung radioactivity is not related to gasps induced by caesarean section, or to a vascular diffusion since lung radioactivity was significantly higher than liver or kidneys' radioactivity. The results of these series of experiments demonstrate that amniotic fluid inhalation does exist in foetal rabbit near term.","Respiration of amniotic fluid in near-term foetal rabbit Abs: <strong>OBJECTIVE: </strong>To examine the existence of amniotic fluid inhalation in foetal rabbit near term.<br /><br /><strong>STUDY DESIGN: </strong>Rabbit red cells labelled with 51 radio-chromium (Cr51-S1: Injectable solution sodium chromate, volumic activity: 74 MBq/ml; Cis-BioInternational, France) were injected into the amniotic sac of 24 New Zealand White foetal rabbits (mean gestation: 31 days) at day 25 per-laparotomy. At day 26, just prior to caesarean section, human serum albumin labelled with 125 radio-active iode (125I-HSA) (SERALB-125: human serum albumin labelled with radioactive Iode 125, volumic activity: 185 kBq/ml, Cis-BioInternational, France) was injected into each amniotic sac. The lungs, digestive tracts, kidneys and liver were excised separately and radioactivity counted in each organ.<br /><br /><strong>RESULTS: </strong>On day 26 of gestation, the 51Cr-RC radioactivity rate per gram of tissue in lungs, digestive tract amniotic fluid, liver and kidneys were respectively 1.66 +/- 2.8%, 1.15 +/- 1.6%, 0.015 +/- 0.02% and 0.04 +/- 0.07% of the total amount of radioactivity injected into the amniotic sac at day 25. The lungs' radioactivity was significantly higher than liver (t = 2.94, P &lt; 0.01) or kidneys radioactivity (t = 2.38, P &lt; 0.05). The 125I-HSA injected just prior to caesarean section at day 26 was not found in any foetal organ.<br /><br /><strong>CONCLUSIONS: </strong>Lung radioactivity is not related to gasps induced by caesarean section, or to a vascular diffusion since lung radioactivity was significantly higher than liver or kidneys' radioactivity. The results of these series of experiments demonstrate that amniotic fluid inhalation does exist in foetal rabbit near term."
1235652,Condé-Salazar et al. 1995,Occupational allergic contact dermatitis in construction workers,"We report the patch test results of 449 construction workers who came as patients to the Occupational Dermatology Service of the Instituto Nacional de Medicina y Seguridad del Trabajo in Madrid between 1989 and 1993. 90.8% of them were patch tested, because they had cutaneous lesions or a clinical history suggestive of occupational dermatitis. 65.5% (268) of those patch tested showed one or more reactions connected with their work. Chromate at 42.1% was the main allergen, followed by cobalt, 20.5%, nickel, 10%, and epoxy resin, 7.5%. 25.9% (106) of patients showed sensitization to rubber components, the majority at 23.7% to thiuram mix, with TETD being the main allergen.","Occupational allergic contact dermatitis in construction workers Abs: We report the patch test results of 449 construction workers who came as patients to the Occupational Dermatology Service of the Instituto Nacional de Medicina y Seguridad del Trabajo in Madrid between 1989 and 1993. 90.8% of them were patch tested, because they had cutaneous lesions or a clinical history suggestive of occupational dermatitis. 65.5% (268) of those patch tested showed one or more reactions connected with their work. Chromate at 42.1% was the main allergen, followed by cobalt, 20.5%, nickel, 10%, and epoxy resin, 7.5%. 25.9% (106) of patients showed sensitization to rubber components, the majority at 23.7% to thiuram mix, with TETD being the main allergen."
1235649,Wenzel et al. 1995,Adhesion of head and neck squamous cell carcinoma to endothelial cells. The missing links,"<strong>OBJECTIVES: </strong>To examine the direct adhesion of head and neck squamous cell carcinoma (HNSCC) cells to basal and cytokine-activated human endothelial cells and to determine the cell adhesion molecules (CAMs) that mediate binding under these two conditions.<br /><br /><strong>DESIGN: </strong>Using an established model of tumor metastasis, the adhesion of four HNSCC cell lines to human umbilical vein endothelial cell (HUVEC) monolayers was examined, with and without pretreatment of HUVEC with tumor necrosis factor alpha (TNF-alpha). Surface CAM expression of HNSCC and HUVEC was determined by flow cytometry, and the results were used to direct studies of adhesion blocking using monoclonal antibodies. The contribution of various CAM to HNSCC binding of basal and cytokine-activated human endothelial cells in vitro was established.<br /><br /><strong>MAIN OUTCOME MEASURES: </strong>Adhesion of HNSCC to HUVEC monolayers was determined by a sodium chromate Cr 51-labeling assay in the presence or absence of monoclonal antibodies directed against specific CAMs.<br /><br /><strong>RESULTS: </strong>Four HNSCC cell lines were shown by flow cytometry to constitutively express the following CAMs: intercellular CAM-1, CD44, lymphocyte function-associated antigen-3, integrin chains alpha 6 and beta 1, and sialyl Lewis(x). No cell lines expressed lymphocyte function-associated antigen-1 or the integrin subunit alpha 4. Adhesion of JHU-011-SCC to TNF-alpha-activated HUVEC was enhanced above the untreated level in a time-dependent manner, with maximal adhesion at 12 hours. This increase correlated with endothelial-selectin expression by HUVEC and HNSCC expression of its ligand sialyl Lewis(x). Monoclonal antibody to sialyl Lewis(x) blocked the increased adhesion to TNF-alpha-activated HUVEC in two of four HNSCC cell lines. Monoclonal antibody to the alpha 6 integrin reduced binding to TNF-alpha-activated and non-activated HUVEC and to subendothelial matrix, but not to fibronectin.<br /><br /><strong>CONCLUSIONS: </strong>Studies of four HNSCC cell lines disclosed a consistent and distinctive pattern of adhesion molecule expression. The alpha 6 integrin subunit may be involved in direct adhesion to nonactivate and cytokine-activated endothelial cells or to laminin present on the endothelial surface. Sialyl Lewis(x) was more specifically involved in the increased adhesion to cytokine-activated HUVEC. This suggests that the sialyl Lewis(x)-endothelial-selectin ligand interaction may be important in facilitating HNSCC adhesion during metastasis to sites of active or chronic inflammation in vivo.","Adhesion of head and neck squamous cell carcinoma to endothelial cells. The missing links Abs: <strong>OBJECTIVES: </strong>To examine the direct adhesion of head and neck squamous cell carcinoma (HNSCC) cells to basal and cytokine-activated human endothelial cells and to determine the cell adhesion molecules (CAMs) that mediate binding under these two conditions.<br /><br /><strong>DESIGN: </strong>Using an established model of tumor metastasis, the adhesion of four HNSCC cell lines to human umbilical vein endothelial cell (HUVEC) monolayers was examined, with and without pretreatment of HUVEC with tumor necrosis factor alpha (TNF-alpha). Surface CAM expression of HNSCC and HUVEC was determined by flow cytometry, and the results were used to direct studies of adhesion blocking using monoclonal antibodies. The contribution of various CAM to HNSCC binding of basal and cytokine-activated human endothelial cells in vitro was established.<br /><br /><strong>MAIN OUTCOME MEASURES: </strong>Adhesion of HNSCC to HUVEC monolayers was determined by a sodium chromate Cr 51-labeling assay in the presence or absence of monoclonal antibodies directed against specific CAMs.<br /><br /><strong>RESULTS: </strong>Four HNSCC cell lines were shown by flow cytometry to constitutively express the following CAMs: intercellular CAM-1, CD44, lymphocyte function-associated antigen-3, integrin chains alpha 6 and beta 1, and sialyl Lewis(x). No cell lines expressed lymphocyte function-associated antigen-1 or the integrin subunit alpha 4. Adhesion of JHU-011-SCC to TNF-alpha-activated HUVEC was enhanced above the untreated level in a time-dependent manner, with maximal adhesion at 12 hours. This increase correlated with endothelial-selectin expression by HUVEC and HNSCC expression of its ligand sialyl Lewis(x). Monoclonal antibody to sialyl Lewis(x) blocked the increased adhesion to TNF-alpha-activated HUVEC in two of four HNSCC cell lines. Monoclonal antibody to the alpha 6 integrin reduced binding to TNF-alpha-activated and non-activated HUVEC and to subendothelial matrix, but not to fibronectin.<br /><br /><strong>CONCLUSIONS: </strong>Studies of four HNSCC cell lines disclosed a consistent and distinctive pattern of adhesion molecule expression. The alpha 6 integrin subunit may be involved in direct adhesion to nonactivate and cytokine-activated endothelial cells or to laminin present on the endothelial surface. Sialyl Lewis(x) was more specifically involved in the increased adhesion to cytokine-activated HUVEC. This suggests that the sialyl Lewis(x)-endothelial-selectin ligand interaction may be important in facilitating HNSCC adhesion during metastasis to sites of active or chronic inflammation in vivo."
1235645,Hassoun and  Stohs 1995,"Chromium-induced production of reactive oxygen species, DNA single-strand breaks, nitric oxide production, and lactate dehydrogenase leakage in J774A.1 cell cultures","The involvement of oxidative stress in the toxicity of chromium (VI) and chromium (III) has been proposed. We have therefore examined the effects of these cations on the production of superoxide anion, nitric oxide (NO), and DNA single strand breaks (SSB) in J774A.1 macrophage cells in culture as well as the effects on lactate dehydrogenase (LDH) leakage and cell viability. Following a 48 hour incubation, over twofold increases in superoxide anion and NO production were observed at concentrations of approximately 0.30 and 50 microM for Cr (VI) and Cr (III), respectively. The patterns of cell viability and LDH leakage paralleled superoxide anion and NO production for Cr (VI) and Cr (III). A 50% decrease in viability was observed at approximately the concentrations that produced a twofold increase in superoxide and NO production. Concentration-dependent increases in DNA-SSB were observed after incubation with Cr (III) with maximum increases occurring at a concentration of approximately 60 microM. Cr (VI) had no effect on the incidence of DNA-SSB at any of the tested concentrations. The results indicate that Cr (VI) and Cr (III) are toxic to the J774A.1 cell line, and the toxicity may be due at least in part to an oxidative stress induced by the production of reactive oxygen species.","Chromium-induced production of reactive oxygen species, DNA single-strand breaks, nitric oxide production, and lactate dehydrogenase leakage in J774A.1 cell cultures Abs: The involvement of oxidative stress in the toxicity of chromium (VI) and chromium (III) has been proposed. We have therefore examined the effects of these cations on the production of superoxide anion, nitric oxide (NO), and DNA single strand breaks (SSB) in J774A.1 macrophage cells in culture as well as the effects on lactate dehydrogenase (LDH) leakage and cell viability. Following a 48 hour incubation, over twofold increases in superoxide anion and NO production were observed at concentrations of approximately 0.30 and 50 microM for Cr (VI) and Cr (III), respectively. The patterns of cell viability and LDH leakage paralleled superoxide anion and NO production for Cr (VI) and Cr (III). A 50% decrease in viability was observed at approximately the concentrations that produced a twofold increase in superoxide and NO production. Concentration-dependent increases in DNA-SSB were observed after incubation with Cr (III) with maximum increases occurring at a concentration of approximately 60 microM. Cr (VI) had no effect on the incidence of DNA-SSB at any of the tested concentrations. The results indicate that Cr (VI) and Cr (III) are toxic to the J774A.1 cell line, and the toxicity may be due at least in part to an oxidative stress induced by the production of reactive oxygen species."
1235643,Leung and  Galbraith 1995,Elevated serum chromium in patients on total parenteral nutrition and the ionic species of contaminant chromium,"Chromium (Cr), an essential micronutrient required for glucose metabolism, was found in high concentrations in up to 94% of the patients on short-term total parenteral nutrition. Approximately 50% had serum levels &gt; 10-fold of normal (upper reference value of 3.8 nmol/L), about 18% were &gt; 20-fold, and about 2% were 40-fold higher. The major Cr contaminant was detected in the amino acid constituents, and was found to have the trivalent ionic form. Although trivalent Cr is reported to be less genotoxic, further study is required to determine the effects on cells exposed to high concentrations of this element during parenteral nutrition over an extended period of time.","Elevated serum chromium in patients on total parenteral nutrition and the ionic species of contaminant chromium Abs: Chromium (Cr), an essential micronutrient required for glucose metabolism, was found in high concentrations in up to 94% of the patients on short-term total parenteral nutrition. Approximately 50% had serum levels &gt; 10-fold of normal (upper reference value of 3.8 nmol/L), about 18% were &gt; 20-fold, and about 2% were 40-fold higher. The major Cr contaminant was detected in the amino acid constituents, and was found to have the trivalent ionic form. Although trivalent Cr is reported to be less genotoxic, further study is required to determine the effects on cells exposed to high concentrations of this element during parenteral nutrition over an extended period of time."
1235640,Appenroth et al. 1996,Contribution to the mechanism of chromate nephrotoxicity in developing rats: EPR investigations,"The effect of 2 mg and 1 mg Na2Cr2O7 (Cr)/100 g body wt. on renal function was investigated in 10- and 55-day-old rats, respectively. These doses were followed by equal Cr concentrations in the renal tissue of both age groups. Confirming previous data we found lower nephrotoxicity in young than in adult rats. The concentration of glutathione (GSH) and the activity of glutathione reductase (GSSG reductase) in renal tissue of adult rats were diminished by buthionine sulfoximine (BSO) and lomustine (CCNU) administration, respectively. In these animals Cr nephrotoxicity was decreased significantly. Lower nephrotoxicity was accompanied by slower disappearance of Cr(VI) from renal tissue homogenate in vitro. The time course of Cr(VI) reduction demonstrated by the signal intensity of Cr(V), as recorded by electron spin resonance (EPR) spectroscopy in the supernatant of renal tissue homogenate, enabled us to follow the reduction of Cr(VI) to Cr(III) via Cr(V). Maximally reached Cr(V) concentrations lowest in young rats, did not differ significantly in adult control and BSO and BSO + CCNU treated rats. Further reduction of Cr(V) to Cr(III) which appeared most rapidly in adult rats, was delayed by pretreatment with BSO and CCNU. From our results we concluded that (1) reduction of Cr(VI) was more related to the concentration of GSH than to the activity of GSSG reductase, (2) the formation of Cr-GSH-complexes with GSH oxidation seemed to be the first step of Cr(VI) metabolism, and (3) the stabilization of reactive Cr(V) by GSH seemed to be decisive for the preventive effect of BSO and CCNU as well as for age differences in chromate nephrotoxicity.","Contribution to the mechanism of chromate nephrotoxicity in developing rats: EPR investigations Abs: The effect of 2 mg and 1 mg Na2Cr2O7 (Cr)/100 g body wt. on renal function was investigated in 10- and 55-day-old rats, respectively. These doses were followed by equal Cr concentrations in the renal tissue of both age groups. Confirming previous data we found lower nephrotoxicity in young than in adult rats. The concentration of glutathione (GSH) and the activity of glutathione reductase (GSSG reductase) in renal tissue of adult rats were diminished by buthionine sulfoximine (BSO) and lomustine (CCNU) administration, respectively. In these animals Cr nephrotoxicity was decreased significantly. Lower nephrotoxicity was accompanied by slower disappearance of Cr(VI) from renal tissue homogenate in vitro. The time course of Cr(VI) reduction demonstrated by the signal intensity of Cr(V), as recorded by electron spin resonance (EPR) spectroscopy in the supernatant of renal tissue homogenate, enabled us to follow the reduction of Cr(VI) to Cr(III) via Cr(V). Maximally reached Cr(V) concentrations lowest in young rats, did not differ significantly in adult control and BSO and BSO + CCNU treated rats. Further reduction of Cr(V) to Cr(III) which appeared most rapidly in adult rats, was delayed by pretreatment with BSO and CCNU. From our results we concluded that (1) reduction of Cr(VI) was more related to the concentration of GSH than to the activity of GSSG reductase, (2) the formation of Cr-GSH-complexes with GSH oxidation seemed to be the first step of Cr(VI) metabolism, and (3) the stabilization of reactive Cr(V) by GSH seemed to be decisive for the preventive effect of BSO and CCNU as well as for age differences in chromate nephrotoxicity."
1235636,Luo et al. 1996,Chromium (IV)-mediated fenton-like reaction causes DNA damage: implication to genotoxicity of chromate,"This paper describes our deoxyribonucleic acid (DNA) damage and Fenton activity studies on Cr(IV) that were undertaken to examine a role of Cr(IV) in the biochemical mechanism of genotoxicity of Cr(VI) compounds. A Cr(IV)-containing compound, a Cr(IV)-ester, was synthesized and used as the first model compound for Cr(IV) studies. Electron spin resonance measurements demonstrated that in the presence of H2O2, this Cr(IV) compound acts as a potent Fenton-like reagent, i.e., it generates OH radical and a Cr(V) species (g = 1.9787) via: Cr(IV) + H2O2--&gt;Cr(V) + OH + OH-. Measurements of OH yield as a function of H2O2 concentration showed that Cr(IV) is more potent than Cr(V) in generating OH. DNA damage assays demonstrate that Cr(IV) and the Cr(IV)/H2O2-generated OH radical can cause DNA strand breaks. The DNA damage caused by OH radical can be effectively blocked by OH radical scavengers. These results thus constitute the first direct evidence for DNA damage by Cr(IV) and Cr(IV)-mediated Fenton-like reaction and support the conjecture that Cr(IV) plays a significant role in the biochemical mechanism of the genotoxic reactions of Cr(VI) compounds and that this effect can be modulated by suitable antiradical agents.","Chromium (IV)-mediated fenton-like reaction causes DNA damage: implication to genotoxicity of chromate Abs: This paper describes our deoxyribonucleic acid (DNA) damage and Fenton activity studies on Cr(IV) that were undertaken to examine a role of Cr(IV) in the biochemical mechanism of genotoxicity of Cr(VI) compounds. A Cr(IV)-containing compound, a Cr(IV)-ester, was synthesized and used as the first model compound for Cr(IV) studies. Electron spin resonance measurements demonstrated that in the presence of H2O2, this Cr(IV) compound acts as a potent Fenton-like reagent, i.e., it generates OH radical and a Cr(V) species (g = 1.9787) via: Cr(IV) + H2O2--&gt;Cr(V) + OH + OH-. Measurements of OH yield as a function of H2O2 concentration showed that Cr(IV) is more potent than Cr(V) in generating OH. DNA damage assays demonstrate that Cr(IV) and the Cr(IV)/H2O2-generated OH radical can cause DNA strand breaks. The DNA damage caused by OH radical can be effectively blocked by OH radical scavengers. These results thus constitute the first direct evidence for DNA damage by Cr(IV) and Cr(IV)-mediated Fenton-like reaction and support the conjecture that Cr(IV) plays a significant role in the biochemical mechanism of the genotoxic reactions of Cr(VI) compounds and that this effect can be modulated by suitable antiradical agents."
1235634,Shirakawa and  Morimoto 1996,Brief reversible bronchospasm resulting from bichromate exposure,"A 50-y-old male worker developed an asthmatic reaction after exposure to bichromate in a metal-plating plant. Evaluation included skin tests, bronchial provocation tests, and specific radioallergosorbent tests with metal salts. A 49-y-old worker who suffered from hard metal asthma was the control. These workers were not atopic, and they exhibited similar bronchial hyperresponsiveness in methacholine-PC20 (74 mg/ml versus 81 mg/ml, respectively) and IgE titers (129 IU/ml versus 130 IU/ml). Positive intradermal and patch tests to bichromate were found in the subject. A bronchial provocation test with inhalation of .01 % bichromate produced an immediate decrease in forced vital capacity in 1 s, followed by a rapid recovery within 5 min absent any treatment. There was no reaction to cobalt (1% cobalt chloride) or to nickel (2% nickel sulfate) salts. In the control, a positive bronchial provocation occurred (absent chromium) with cobalt and nickel. Administration of a subcutaneous preparation of 1 mg atropine sulfate or of 1 puff of disodium cromoglycate or beta-stimulant reduced bronchial responsiveness to methacholine-PC20, and no asthmatic reaction occurred following inhalation of 1% bichromate. No blocking of asthmatic reaction occurred after pretreatment with beclomethasone dipropionate inhalation. Administration of propranolol, however, potentiated the acute bronchoconstriction induced by bichromate. The 50-y-old worker had evidence of IgE antibody to chromium-conjugated human serum albumin and to chromium-conjugated exchange resin. His serum selectively bound 51Cr, but antibodies specific to cobalt and nickel were absent. These results, if viewed collectively, suggest that bichromate exposure causes brief reversible bronchospasm via alteration of autonomic balance and increased vagal activation.","Brief reversible bronchospasm resulting from bichromate exposure Abs: A 50-y-old male worker developed an asthmatic reaction after exposure to bichromate in a metal-plating plant. Evaluation included skin tests, bronchial provocation tests, and specific radioallergosorbent tests with metal salts. A 49-y-old worker who suffered from hard metal asthma was the control. These workers were not atopic, and they exhibited similar bronchial hyperresponsiveness in methacholine-PC20 (74 mg/ml versus 81 mg/ml, respectively) and IgE titers (129 IU/ml versus 130 IU/ml). Positive intradermal and patch tests to bichromate were found in the subject. A bronchial provocation test with inhalation of .01 % bichromate produced an immediate decrease in forced vital capacity in 1 s, followed by a rapid recovery within 5 min absent any treatment. There was no reaction to cobalt (1% cobalt chloride) or to nickel (2% nickel sulfate) salts. In the control, a positive bronchial provocation occurred (absent chromium) with cobalt and nickel. Administration of a subcutaneous preparation of 1 mg atropine sulfate or of 1 puff of disodium cromoglycate or beta-stimulant reduced bronchial responsiveness to methacholine-PC20, and no asthmatic reaction occurred following inhalation of 1% bichromate. No blocking of asthmatic reaction occurred after pretreatment with beclomethasone dipropionate inhalation. Administration of propranolol, however, potentiated the acute bronchoconstriction induced by bichromate. The 50-y-old worker had evidence of IgE antibody to chromium-conjugated human serum albumin and to chromium-conjugated exchange resin. His serum selectively bound 51Cr, but antibodies specific to cobalt and nickel were absent. These results, if viewed collectively, suggest that bichromate exposure causes brief reversible bronchospasm via alteration of autonomic balance and increased vagal activation."
1235629,Costa et al. 1996,Monitoring human lymphocytic DNA-protein cross-links as biomarkers of biologically active doses of chromate,"A simple and sensitive assay for DNA-protein cross-links has been used as a biomarker of chromate exposure and early carcinogenic effects. Pilot studies of DNA-protein cross-links in peripheral blood lymphocytes have been conducted with individuals who had higher exposure to chromate, including welders, and with individuals who had lower levels of exposure such as residents living in a chromium-contaminated area in Jersey City, New Jersey. Studies were also conducted in two Bulgarian cities (Jambol and Burgas) with different levels of air pollution and Cr(VI) exposure and in chrome platers in Bulgaria who had high exposure to chromate. DNA-protein cross-links in U.S. welders and in individuals living in Hudson County, New Jersey around chromium-contaminated areas were significantly higher compared to matched controls. Although blood and urinary levels of chromium were not extensively studied in these populations, we were able to obtain these measurements in the Bulgarian population. Chromium levels in red blood cells of controls living in Burgas were in the order of 1 to 2 ppb chromium, and these individuals had the lowest levels of DNA-protein cross-links. However, the chromium levels in Jambol ranged from about 2 to 7 ppb in red blood cells of city residents to about 22 ppb in chrome platers. DNA-protein cross-links were saturated at about 7 to 8 ppb chromium in the red blood cells, and cross-links correlated well only with chromium levels in red blood cells. Urinary chromium levels did not correlate well with either DNA-protein cross-links or chromium levels in with red blood cells.","Monitoring human lymphocytic DNA-protein cross-links as biomarkers of biologically active doses of chromate Abs: A simple and sensitive assay for DNA-protein cross-links has been used as a biomarker of chromate exposure and early carcinogenic effects. Pilot studies of DNA-protein cross-links in peripheral blood lymphocytes have been conducted with individuals who had higher exposure to chromate, including welders, and with individuals who had lower levels of exposure such as residents living in a chromium-contaminated area in Jersey City, New Jersey. Studies were also conducted in two Bulgarian cities (Jambol and Burgas) with different levels of air pollution and Cr(VI) exposure and in chrome platers in Bulgaria who had high exposure to chromate. DNA-protein cross-links in U.S. welders and in individuals living in Hudson County, New Jersey around chromium-contaminated areas were significantly higher compared to matched controls. Although blood and urinary levels of chromium were not extensively studied in these populations, we were able to obtain these measurements in the Bulgarian population. Chromium levels in red blood cells of controls living in Burgas were in the order of 1 to 2 ppb chromium, and these individuals had the lowest levels of DNA-protein cross-links. However, the chromium levels in Jambol ranged from about 2 to 7 ppb in red blood cells of city residents to about 22 ppb in chrome platers. DNA-protein cross-links were saturated at about 7 to 8 ppb chromium in the red blood cells, and cross-links correlated well only with chromium levels in red blood cells. Urinary chromium levels did not correlate well with either DNA-protein cross-links or chromium levels in with red blood cells."
1235627,Chen and  Christou 1996,Relative contribution of endothelial cell and polymorphonuclear neutrophil activation in their interactions in systemic inflammatory response syndrome,"<strong>OBJECTIVE: </strong>To examine the relative contribution of polymorphonuclear neutrophil (PMN) vs endothelial cell (EC) activation on the adherence and subsequent killing of ECs by PMNs.<br /><br /><strong>DESIGN: </strong>In vitro comparative studies of PMN-EC adherence and cytotoxicity.<br /><br /><strong>SETTING: </strong>Research laboratory and the surgical intensive care unit of a tertiary-level university hospital.<br /><br /><strong>PATIENTS: </strong>Patients with systemic inflammatory response syndrome admitted to the surgical intensive care unit and hospitalized preoperative noninfected surgical patients.<br /><br /><strong>INTERVENTION: </strong>None.<br /><br /><strong>METHODS: </strong>Polymorphonuclear neutrophils were isolated from 21 healthy volunteers, 22 preoperative patients, and 30 patients from the surgical intensive care unit with systemic inflammatory response syndrome. The PMNs were activated with lipopolysaccharide, 100 ng/mL (Escherichia coli 0111:b4), for 40 minutes at 37 degrees C before the adherence and cytotoxicity assays. Human umbilical vein endothelial monolayers were stimulated with tumor necrosis factor alpha, 25 ng/mL, and interleukin 1 beta, 15 U/mL, for 3 hours. The PMNs or EC cells were labeled with sodium chromate Cr 51 and used in a standard adherence or killing assay as required.<br /><br /><strong>RESULTS: </strong>Control and preoperative patient PMN treatment with lipopolysaccharide produced a modest increase in adherence. The PMNs from patients with systemic inflammatory response syndrome showed moderately increased human umbilical vein endothelial cell adherence, and this could not be augmented further with lipopolysaccharide stimulation. There was a marked increase in PMN adherence to EC after EC activation in all study groups (P &lt; .001). Similar to the adherence data, human umbilical vein endothelial cell cytotoxicity was significantly increased in all groups after human umbilical vein endothelial cell activation (P &lt; .01) but not after PMN stimulation with lipopolysaccharide.<br /><br /><strong>CONCLUSION: </strong>These data suggest that stimulation of ECs is far more important in producing increased adherence and cytotoxicity of EC than PMN stimulation with lipopolysaccharide in all study groups. Therapeutic efforts in patients with systemic inflammatory response syndrome should be focused on the EC.","Relative contribution of endothelial cell and polymorphonuclear neutrophil activation in their interactions in systemic inflammatory response syndrome Abs: <strong>OBJECTIVE: </strong>To examine the relative contribution of polymorphonuclear neutrophil (PMN) vs endothelial cell (EC) activation on the adherence and subsequent killing of ECs by PMNs.<br /><br /><strong>DESIGN: </strong>In vitro comparative studies of PMN-EC adherence and cytotoxicity.<br /><br /><strong>SETTING: </strong>Research laboratory and the surgical intensive care unit of a tertiary-level university hospital.<br /><br /><strong>PATIENTS: </strong>Patients with systemic inflammatory response syndrome admitted to the surgical intensive care unit and hospitalized preoperative noninfected surgical patients.<br /><br /><strong>INTERVENTION: </strong>None.<br /><br /><strong>METHODS: </strong>Polymorphonuclear neutrophils were isolated from 21 healthy volunteers, 22 preoperative patients, and 30 patients from the surgical intensive care unit with systemic inflammatory response syndrome. The PMNs were activated with lipopolysaccharide, 100 ng/mL (Escherichia coli 0111:b4), for 40 minutes at 37 degrees C before the adherence and cytotoxicity assays. Human umbilical vein endothelial monolayers were stimulated with tumor necrosis factor alpha, 25 ng/mL, and interleukin 1 beta, 15 U/mL, for 3 hours. The PMNs or EC cells were labeled with sodium chromate Cr 51 and used in a standard adherence or killing assay as required.<br /><br /><strong>RESULTS: </strong>Control and preoperative patient PMN treatment with lipopolysaccharide produced a modest increase in adherence. The PMNs from patients with systemic inflammatory response syndrome showed moderately increased human umbilical vein endothelial cell adherence, and this could not be augmented further with lipopolysaccharide stimulation. There was a marked increase in PMN adherence to EC after EC activation in all study groups (P &lt; .001). Similar to the adherence data, human umbilical vein endothelial cell cytotoxicity was significantly increased in all groups after human umbilical vein endothelial cell activation (P &lt; .01) but not after PMN stimulation with lipopolysaccharide.<br /><br /><strong>CONCLUSION: </strong>These data suggest that stimulation of ECs is far more important in producing increased adherence and cytotoxicity of EC than PMN stimulation with lipopolysaccharide in all study groups. Therapeutic efforts in patients with systemic inflammatory response syndrome should be focused on the EC."
1235626,Yamada et al. 1996,Mouse islet cell lysis mediated by interleukin-1-induced Fas,"This study was conducted to investigate the possible involvement of Fas in beta-cell death in insulitis of Type 1 (insulin-dependent) diabetes mellitus. Although primary cultured Balb/c mouse islet cells did not express Fas mRNA, 4-12 hours of treatment with 10(2)-10(3) U/l of mouse interleukin-1 alpha (IL-1 alpha) induced the expression of Fas mRNA. Surface Fas expression was detected by immunofluorescence flow cytometry using a non-cytolytic anti-Fas monoclonal antibody after 6 or 12 h of incubation with 10(3) U/l of IL-1 alpha. Primary islet cells were resistant to an agonistic anti-Fas monoclonal antibody. However, 12 h pretreatment with IL-1 alpha sensitized islet cells to its cytolytic effect. Significant cell death was observed 24 h after the addition of anti-Fas, and progressively increased until 72 h, when specific 51Cr release was 72 +/- 6%. Agarose gel electrophoresis of DNA extracted from cells exposed to IL-1 alpha and agonistic anti-Fas showed internucleosomal DNA fragmentation, a hallmark of apoptotic cell death. Since the Fas antibody showed no cross-reactive activity of tumour necrosis factor (TNF), the cytotoxic effect was not mediated by TNF receptors. A protein synthesis inhibitor cycloheximide augmented Fas-mediated islet cell death. The Fas-mediated killing of islet cells was not L-arginine-dependent, or blocked by N(G)-monomethyl-L-arginine. beta-TC1 cells also expressed Fas mRNA when exposed to IL-1 alpha or IL-1 alpha plus interferon-gamma. These observations suggest that Fas-mediated apoptosis may be a mechanism of islet cell death in autoimmune insulitis.","Mouse islet cell lysis mediated by interleukin-1-induced Fas Abs: This study was conducted to investigate the possible involvement of Fas in beta-cell death in insulitis of Type 1 (insulin-dependent) diabetes mellitus. Although primary cultured Balb/c mouse islet cells did not express Fas mRNA, 4-12 hours of treatment with 10(2)-10(3) U/l of mouse interleukin-1 alpha (IL-1 alpha) induced the expression of Fas mRNA. Surface Fas expression was detected by immunofluorescence flow cytometry using a non-cytolytic anti-Fas monoclonal antibody after 6 or 12 h of incubation with 10(3) U/l of IL-1 alpha. Primary islet cells were resistant to an agonistic anti-Fas monoclonal antibody. However, 12 h pretreatment with IL-1 alpha sensitized islet cells to its cytolytic effect. Significant cell death was observed 24 h after the addition of anti-Fas, and progressively increased until 72 h, when specific 51Cr release was 72 +/- 6%. Agarose gel electrophoresis of DNA extracted from cells exposed to IL-1 alpha and agonistic anti-Fas showed internucleosomal DNA fragmentation, a hallmark of apoptotic cell death. Since the Fas antibody showed no cross-reactive activity of tumour necrosis factor (TNF), the cytotoxic effect was not mediated by TNF receptors. A protein synthesis inhibitor cycloheximide augmented Fas-mediated islet cell death. The Fas-mediated killing of islet cells was not L-arginine-dependent, or blocked by N(G)-monomethyl-L-arginine. beta-TC1 cells also expressed Fas mRNA when exposed to IL-1 alpha or IL-1 alpha plus interferon-gamma. These observations suggest that Fas-mediated apoptosis may be a mechanism of islet cell death in autoimmune insulitis."
1235625,Alexander et al. 1996,Lung cancer in chromate-exposed aerospace workers,"A retrospective cohort study evaluated the risk of lung cancer in aerospace workers with minimum of 6 months' employment in jobs with chromium [VI] exposure (n = 2429). Standardized incidence ratios (SIR) estimated the risk of lung cancer by duration of employment in chromate-exposure jobs and cumulative exposure based on industrial hygiene and work-history data. The overall SIR for lung cancer was 0.8 (observed [Obs] = 15). Lung cancer risk was inversely related to estimates of cumulative chromate exposure and duration of employment as a painter. Although based on few cases, an elevated lung cancer risk was found in subjects who had worked for 5 or more years as a chrome plater or surface processor tank tender (Obs = 2, SIR = 1.9) and sander/masker or polisher (Obs = 3, SIR = 2.7). A clear association was not observed between chromate exposure and the risk of lung cancer in this population of workers.","Lung cancer in chromate-exposed aerospace workers Abs: A retrospective cohort study evaluated the risk of lung cancer in aerospace workers with minimum of 6 months' employment in jobs with chromium [VI] exposure (n = 2429). Standardized incidence ratios (SIR) estimated the risk of lung cancer by duration of employment in chromate-exposure jobs and cumulative exposure based on industrial hygiene and work-history data. The overall SIR for lung cancer was 0.8 (observed [Obs] = 15). Lung cancer risk was inversely related to estimates of cumulative chromate exposure and duration of employment as a painter. Although based on few cases, an elevated lung cancer risk was found in subjects who had worked for 5 or more years as a chrome plater or surface processor tank tender (Obs = 2, SIR = 1.9) and sander/masker or polisher (Obs = 3, SIR = 2.7). A clear association was not observed between chromate exposure and the risk of lung cancer in this population of workers."
1235622,Julia and  Buéno 1997,Tachykininergic mediation of viscerosensitive responses to acute inflammation in rats: role of CGRP,"Tachykinins, colocalized with calcitonin gene-related peptides (CGRP) in sensory afferents, are involved in viscerosensitive responses. We investigated the role of tachykinins and CGRP in both nociceptive and visceromotor responses to inflammation. Visceral pain was assessed by abdominal muscle contractions. Gastric emptying was evaluated after gavage with reconstituted milk containing 51Cr-labeled sodium chromate. Acetic acid or 9% NaCl was injected intraperitoneally before the meal. RP-67580, SR-48968, human CGRP [hCGRP-(8-37)], or their vehicles were injected before acetic acid or saline. RP-67580, SR-48968, or their vehicles were injected before CGRP and the meal. GR-73632 or GR-76349 was injected before the meal. Acetic acids inhibited gastric emptying and increased the number of abdominal contractions. RP-67580 reduced the inhibition of gastric emptying without affecting the abdominal response. SR-48968 only reduced the acetic acid-induced increase of abdominal contractions. hCGRP-(8-37) reduced both responses induced by acetic acid. CGRP mimicked the effects of acetic acid. RP-67580 abolished CGRP-induced gastric emptying inhibition, whereas SR-48968 only diminished visceral pain. GR-73632 reduced gastric emptying, and GR-64349 increased abdominal response. In inflammation, neurokinin receptors (NK1 and NK2) mediate the gastric emptying inhibition and visceral pain, respectively. These responses involve a release of CGRP.","Tachykininergic mediation of viscerosensitive responses to acute inflammation in rats: role of CGRP Abs: Tachykinins, colocalized with calcitonin gene-related peptides (CGRP) in sensory afferents, are involved in viscerosensitive responses. We investigated the role of tachykinins and CGRP in both nociceptive and visceromotor responses to inflammation. Visceral pain was assessed by abdominal muscle contractions. Gastric emptying was evaluated after gavage with reconstituted milk containing 51Cr-labeled sodium chromate. Acetic acid or 9% NaCl was injected intraperitoneally before the meal. RP-67580, SR-48968, human CGRP [hCGRP-(8-37)], or their vehicles were injected before acetic acid or saline. RP-67580, SR-48968, or their vehicles were injected before CGRP and the meal. GR-73632 or GR-76349 was injected before the meal. Acetic acids inhibited gastric emptying and increased the number of abdominal contractions. RP-67580 reduced the inhibition of gastric emptying without affecting the abdominal response. SR-48968 only reduced the acetic acid-induced increase of abdominal contractions. hCGRP-(8-37) reduced both responses induced by acetic acid. CGRP mimicked the effects of acetic acid. RP-67580 abolished CGRP-induced gastric emptying inhibition, whereas SR-48968 only diminished visceral pain. GR-73632 reduced gastric emptying, and GR-64349 increased abdominal response. In inflammation, neurokinin receptors (NK1 and NK2) mediate the gastric emptying inhibition and visceral pain, respectively. These responses involve a release of CGRP."
1235621,Satoh et al. 1997,A follow-up study of progression from dysplasia to squamous cell carcinoma with immunohistochemical examination of p53 protein overexpression in the bronchi of ex-chromate workers,"Squamous cell carcinoma (SCC) of the bronchus is considered to develop from preneoplastic 'dysplasia', but reports of sequential observation of this dysplasia-carcinoma sequence in humans are very few. We followed four dysplastic lesions found in the bronchi of three ex-chromate workers by bronchoscopy and biopsy and found that all of them progressed to SCC. Of the four lesions, three were severe dysplasias at the first biopsy which progressed to SCCs in 7-13 months. The last one was a slight dysplasia at the first biopsy and showed progression of the atypia to carcinoma in 6 years and 10 months. An immunohistochemical analysis of the chronological change in p53 protein expression in these lesions and in normal ciliated epithelium taken from the surroundings was conducted in each case. Overexpression of p53 protein was observed in two of the severe dysplasias and the one slight dysplasia, as well as their eventual SCCs. However, no such change was apparent in one case of severe dysplasia or its eventual SCC. Normal epithelium was consistently negative. Our results provide direct proof of the dysplasia-carcinoma sequence and suggest that alteration in the expression of p53 protein might be an important early event which persists. Therefore, the immunohistochemical detection of p53 overexpression in biopsy specimens of bronchial epithelium might be useful for evaluation of preneoplastic lesions in high-risk group individuals and for early diagnosis of bronchial cancer.","A follow-up study of progression from dysplasia to squamous cell carcinoma with immunohistochemical examination of p53 protein overexpression in the bronchi of ex-chromate workers Abs: Squamous cell carcinoma (SCC) of the bronchus is considered to develop from preneoplastic 'dysplasia', but reports of sequential observation of this dysplasia-carcinoma sequence in humans are very few. We followed four dysplastic lesions found in the bronchi of three ex-chromate workers by bronchoscopy and biopsy and found that all of them progressed to SCC. Of the four lesions, three were severe dysplasias at the first biopsy which progressed to SCCs in 7-13 months. The last one was a slight dysplasia at the first biopsy and showed progression of the atypia to carcinoma in 6 years and 10 months. An immunohistochemical analysis of the chronological change in p53 protein expression in these lesions and in normal ciliated epithelium taken from the surroundings was conducted in each case. Overexpression of p53 protein was observed in two of the severe dysplasias and the one slight dysplasia, as well as their eventual SCCs. However, no such change was apparent in one case of severe dysplasia or its eventual SCC. Normal epithelium was consistently negative. Our results provide direct proof of the dysplasia-carcinoma sequence and suggest that alteration in the expression of p53 protein might be an important early event which persists. Therefore, the immunohistochemical detection of p53 overexpression in biopsy specimens of bronchial epithelium might be useful for evaluation of preneoplastic lesions in high-risk group individuals and for early diagnosis of bronchial cancer."
1235620,Campos-García et al. 1997,Purification and partial characterization of a chromate reductase from Bacillus,"A soluble NADH-dependent enzyme capable of reducing hexavalent chromium [Cr(VI)] to the trivalent form [Cr(III)] was purified from chromate-resistant Bacillus QC1-2. An enriched single protein band of 24 kDa was observed by SDS-PAGE following HPLC ion-exchange and size-exclusion procedures. In the latter step, the chromate reductase showed a molecular mass of 44 kDa, which suggested that the enzyme consists of two subunits of about 24 kDa. Purified chromate reductase displayed optimal activity at a temperature and pH of 37 degrees C and 7.0, respectively. The enzyme showed a Km of 0.35 mM for chromate and a Vmax of 50 nmol Cr(VI) reduced per minute per mg protein.","Purification and partial characterization of a chromate reductase from Bacillus Abs: A soluble NADH-dependent enzyme capable of reducing hexavalent chromium [Cr(VI)] to the trivalent form [Cr(III)] was purified from chromate-resistant Bacillus QC1-2. An enriched single protein band of 24 kDa was observed by SDS-PAGE following HPLC ion-exchange and size-exclusion procedures. In the latter step, the chromate reductase showed a molecular mass of 44 kDa, which suggested that the enzyme consists of two subunits of about 24 kDa. Purified chromate reductase displayed optimal activity at a temperature and pH of 37 degrees C and 7.0, respectively. The enzyme showed a Km of 0.35 mM for chromate and a Vmax of 50 nmol Cr(VI) reduced per minute per mg protein."
1235619,Bagchi et al. 1997,Comparative in vitro and in vivo protein kinase C activation by selected pesticides and transition metal salts,"Various pesticides and transition metals induce oxidative deterioration of biological macromolecules. Protein kinase C (PKC) may mediate these effects. However, no information is available regarding whether these xenobiotics can modulate PKC which is a critical event signaling the increase in endothelial permeability and cell proliferation. Female Sprague-Dawley rats were treated p.o. with two 0.25 LD50 doses of selected pesticides and transition metal salts at 0 and 21 h, and killed at 24 h. PKC activities were measured in liver and brain tissues. Cultured PC-12 cells were incubated for 24 h with 50, 100 or 200 nM concentrations of these pesticides, while 0.20, 0.40 or 0.60 microM concentrations of cadmium chloride (Cd(II)) and sodium dichromate (Cr(VI)) salts were employed. PKC activations were observed in the hepatic and brain cytosol fractions by all xenobiotics. Approximately 1.4- to 2.0-fold and 1.6- to 3.5-fold increases in PKC activity in the hepatic and brain cytosol fractions were observed, respectively. In the hepatic tissues, the greatest increases in activities were observed with TCDD, chlorpyrifos, endrin and Cd(II), while chlorpyrifos and fenthion exerted the greatest increases in the brain tissues. In cultured PC-12 cells, the greatest activation of PKC was observed primarily with 100-nM concentrations of the pesticides. The maximum effects were induced by chlorpyrifos, fenthion, Cd(II) and Cr(VI) salt. The results clearly indicate that pesticides as well as Cd(II) and Cr(VI) salts can modulate a vital component of the cell signaling pathway, namely PKC activity. PKC may be a target of free radicals and oxidative stress, leading to altered cell proliferation and differentiation.","Comparative in vitro and in vivo protein kinase C activation by selected pesticides and transition metal salts Abs: Various pesticides and transition metals induce oxidative deterioration of biological macromolecules. Protein kinase C (PKC) may mediate these effects. However, no information is available regarding whether these xenobiotics can modulate PKC which is a critical event signaling the increase in endothelial permeability and cell proliferation. Female Sprague-Dawley rats were treated p.o. with two 0.25 LD50 doses of selected pesticides and transition metal salts at 0 and 21 h, and killed at 24 h. PKC activities were measured in liver and brain tissues. Cultured PC-12 cells were incubated for 24 h with 50, 100 or 200 nM concentrations of these pesticides, while 0.20, 0.40 or 0.60 microM concentrations of cadmium chloride (Cd(II)) and sodium dichromate (Cr(VI)) salts were employed. PKC activations were observed in the hepatic and brain cytosol fractions by all xenobiotics. Approximately 1.4- to 2.0-fold and 1.6- to 3.5-fold increases in PKC activity in the hepatic and brain cytosol fractions were observed, respectively. In the hepatic tissues, the greatest increases in activities were observed with TCDD, chlorpyrifos, endrin and Cd(II), while chlorpyrifos and fenthion exerted the greatest increases in the brain tissues. In cultured PC-12 cells, the greatest activation of PKC was observed primarily with 100-nM concentrations of the pesticides. The maximum effects were induced by chlorpyrifos, fenthion, Cd(II) and Cr(VI) salt. The results clearly indicate that pesticides as well as Cd(II) and Cr(VI) salts can modulate a vital component of the cell signaling pathway, namely PKC activity. PKC may be a target of free radicals and oxidative stress, leading to altered cell proliferation and differentiation."
1235614,Kondo et al. 1997,Mutations of the p53 gene in human lung cancer from chromate-exposed workers,"We examined p53 mutations in 20 cancer samples from 19 chromate workers with lung cancer by Polymerase chain reaction-Single strand conformation polymorphism analysis and direct sequencing. Six missense mutations were identified in 4 (20%) of the 20 chromate lung cancer samples. Fewer mutations were found in the patients with lung cancers who had been exposed to chromate than in those who had not. However, the pattern of p53 mutations in lung cancer patients exposed to chromate differed from that of common lung cancers in 3 respects. There were no apparent G to T transversions, which are common base changes in lung cancers. Half of the mutational sites (3/ 6) had changes of AT base-pairs, and 2 of 4 mutational tumor samples had double missense mutations. Our results suggested that chromate exposure may induce point mutation of the p53 gene.","Mutations of the p53 gene in human lung cancer from chromate-exposed workers Abs: We examined p53 mutations in 20 cancer samples from 19 chromate workers with lung cancer by Polymerase chain reaction-Single strand conformation polymorphism analysis and direct sequencing. Six missense mutations were identified in 4 (20%) of the 20 chromate lung cancer samples. Fewer mutations were found in the patients with lung cancers who had been exposed to chromate than in those who had not. However, the pattern of p53 mutations in lung cancer patients exposed to chromate differed from that of common lung cancers in 3 respects. There were no apparent G to T transversions, which are common base changes in lung cancers. Half of the mutational sites (3/ 6) had changes of AT base-pairs, and 2 of 4 mutational tumor samples had double missense mutations. Our results suggested that chromate exposure may induce point mutation of the p53 gene."
1235613,De Flora et al. 1997,Modulation of the potency of promutagens and direct acting mutagens in bacteria by inhibitors of the multidrug resistance mechanism,"Multiple drug resistance (MDR) mechanisms are known to limit the effectiveness of some cancer chemotherapies, probably through enhancing P-glycoprotein-mediated drug efflux from mammalian cells. Similar mechanisms appear to act in other organisms, including bacteria, and may affect not only the toxicity but also the mutagenicity of certain chemicals. At least in some experimental situations, MDR can be overcome through concomitant treatment of the cells with various types of inhibitors. Two MDR inhibitors, verapamil, a calcium channel blocker, and trifluoperazine, a calmodulin inhibitor, were assayed for their ability to modulate the potency of nine mutagens with varying mechanisms of action in various Salmonella typhimurium his- strains. Neither verapamil nor trifluoperazine affected the direct mutagenicity of sodium dichromate and 2-methoxy-6-chloro-9[3-(2-chloroethyl)amino-propyl-amino] dihydrochloride (ICR 191) or the S9-mediated mutagenicity of benzo[a]pyrene and 2-amino-3,4-dimethyl-amidazo[4,5-f]quinoline (MeIQ). Both modulators enhanced the direct mutagenicity of doxorubicin. Moreover, trifluoperazine sharply increased the S9-mediated mutagenicity of cyclophosphamide and 2-aminofluorene, while it consistently decreased the mutagenicity of 3-amino-1-methyl-5H-pyrido[4,3-b]indole (Trp-P-2). The contrasting effect towards the aromatic amine 2-aminofluorene and the heterocyclic amine Trp-P-2, representative of important chemical families responsible for the bacterial mutagenicity of cigarette smoke, may explain the observed lack of influence of trifluoperazine on the mutagenicity of a cigarette smoke condensate. These observations extend the known range of chemical types whose mutagenicity can be modulated by inhibitors of MDR and suggest that there may be value in adding MDR inhibitors, especially trifluoperazine, to optimize the detection of mutagenicity by certain types of chemicals in the Salmonella/mammalian microsome mutagenicity test.","Modulation of the potency of promutagens and direct acting mutagens in bacteria by inhibitors of the multidrug resistance mechanism Abs: Multiple drug resistance (MDR) mechanisms are known to limit the effectiveness of some cancer chemotherapies, probably through enhancing P-glycoprotein-mediated drug efflux from mammalian cells. Similar mechanisms appear to act in other organisms, including bacteria, and may affect not only the toxicity but also the mutagenicity of certain chemicals. At least in some experimental situations, MDR can be overcome through concomitant treatment of the cells with various types of inhibitors. Two MDR inhibitors, verapamil, a calcium channel blocker, and trifluoperazine, a calmodulin inhibitor, were assayed for their ability to modulate the potency of nine mutagens with varying mechanisms of action in various Salmonella typhimurium his- strains. Neither verapamil nor trifluoperazine affected the direct mutagenicity of sodium dichromate and 2-methoxy-6-chloro-9[3-(2-chloroethyl)amino-propyl-amino] dihydrochloride (ICR 191) or the S9-mediated mutagenicity of benzo[a]pyrene and 2-amino-3,4-dimethyl-amidazo[4,5-f]quinoline (MeIQ). Both modulators enhanced the direct mutagenicity of doxorubicin. Moreover, trifluoperazine sharply increased the S9-mediated mutagenicity of cyclophosphamide and 2-aminofluorene, while it consistently decreased the mutagenicity of 3-amino-1-methyl-5H-pyrido[4,3-b]indole (Trp-P-2). The contrasting effect towards the aromatic amine 2-aminofluorene and the heterocyclic amine Trp-P-2, representative of important chemical families responsible for the bacterial mutagenicity of cigarette smoke, may explain the observed lack of influence of trifluoperazine on the mutagenicity of a cigarette smoke condensate. These observations extend the known range of chemical types whose mutagenicity can be modulated by inhibitors of MDR and suggest that there may be value in adding MDR inhibitors, especially trifluoperazine, to optimize the detection of mutagenicity by certain types of chemicals in the Salmonella/mammalian microsome mutagenicity test."
1235611,Peitzsch et al. 1998,Alcaligenes eutrophus as a bacterial chromate sensor,"In Alcaligenes eutrophus CH34, determinants encoding inducible resistance to chromate (chr) and to cobalt and nickel (cnr) are located adjacent to each other on plasmid pMOL28. To develop metal-sensing bacterial strains, a cloned part of plasmid pMOL28, which contains both determinants, was mutated with Tn5-lacZ. The chr::lacZ fusions were specifically induced by chromium; cnr was induced best by Ni2+ but was also induced by Co2+, Mn2+, chromate, Cu2+, Cd2+, and Zn2+. The broad-host-range IncP1 plasmid pEBZ141, which contains a chr::lux fusion, was constructed. A. eutrophus AE104(pEBZ141), carrying a chr::lux transcriptional fusion, could be used as a biosensor for chromate when cultivated in glycerol as an optimal carbon source. Chromate and bichromate were the best inducers; induction by Cr3+ was 10 times lower, and other ions induced only a little or not at all. Interactions among induction of the chr resistance determinant, chromate reduction, chromate accumulation, and the sulfate concentration of the growth medium were demonstrated.","Alcaligenes eutrophus as a bacterial chromate sensor Abs: In Alcaligenes eutrophus CH34, determinants encoding inducible resistance to chromate (chr) and to cobalt and nickel (cnr) are located adjacent to each other on plasmid pMOL28. To develop metal-sensing bacterial strains, a cloned part of plasmid pMOL28, which contains both determinants, was mutated with Tn5-lacZ. The chr::lacZ fusions were specifically induced by chromium; cnr was induced best by Ni2+ but was also induced by Co2+, Mn2+, chromate, Cu2+, Cd2+, and Zn2+. The broad-host-range IncP1 plasmid pEBZ141, which contains a chr::lux fusion, was constructed. A. eutrophus AE104(pEBZ141), carrying a chr::lux transcriptional fusion, could be used as a biosensor for chromate when cultivated in glycerol as an optimal carbon source. Chromate and bichromate were the best inducers; induction by Cr3+ was 10 times lower, and other ions induced only a little or not at all. Interactions among induction of the chr resistance determinant, chromate reduction, chromate accumulation, and the sulfate concentration of the growth medium were demonstrated."
1235604,Halatek et al. 1998,Quantification of Clara cell protein in rat and mouse biological fluids using a sensitive immunoassay,"Clara cell protein is a 16-17 kDa protein (CC16) secreted by Clara cells in the bronchiolar lining fluid of the lung. In order to investigate the potential of this protein as a pulmonary marker in animals, CC16 was isolated from rat bronchoalveolar lavage fluid (BALF) and a sensitive latex immunoassay applicable to both rat and mouse CC16 was developed. The pattern of CC16 concentrations in rat biological fluids determined by the immunoassay was consistent with the hypothesis of a passive diffusion of the protein across the bronchoalveolar/blood barriers showing a difference of more than 5,000 fold between the concentration in the epithelial lining fluid (mean, 140 mg x L(-1)) and that in serum (20 microg x L(-1)) or urine (3 microg x L(-1)). In BALF, the CC16 concentration averaged 5,500 microg x L(-1) and was of the same magnitude as that determined on lung and trachea homogenates. CC16 was also detectable in amniotic fluid with a mean value of 800 microg x L(-1) before delivery. Damage of Clara cells produced by methylcyclopentadienyl manganese tricarbonyl resulted in a significant decrease of CC16 in BALF but did not affect the serum levels of the protein. The nephrotoxicant sodium chromate by contrast had no influence on the CC16 content of BALF but markedly increased CC16 levels in both serum and urine as a result of impaired glomerular filtration and tubular reabsorption, respectively. In conclusion, mouse or rat Clara cell protein of 16-17 kDa can easily be quantified, not only in bronchoalveolar lavage fluid, but also in extrapulmonary fluids such as serum or urine. Thus, in rodents, Clara cell protein of 16-17 kDa follows the same metabolic pathway as in humans, diffusing from the respiratory tract into serum where it is eliminated by the kidneys. This serum Clara cell protein of 16-17 kDa may be useful as a peripheral marker of events taking place in the respiratory tract.","Quantification of Clara cell protein in rat and mouse biological fluids using a sensitive immunoassay Abs: Clara cell protein is a 16-17 kDa protein (CC16) secreted by Clara cells in the bronchiolar lining fluid of the lung. In order to investigate the potential of this protein as a pulmonary marker in animals, CC16 was isolated from rat bronchoalveolar lavage fluid (BALF) and a sensitive latex immunoassay applicable to both rat and mouse CC16 was developed. The pattern of CC16 concentrations in rat biological fluids determined by the immunoassay was consistent with the hypothesis of a passive diffusion of the protein across the bronchoalveolar/blood barriers showing a difference of more than 5,000 fold between the concentration in the epithelial lining fluid (mean, 140 mg x L(-1)) and that in serum (20 microg x L(-1)) or urine (3 microg x L(-1)). In BALF, the CC16 concentration averaged 5,500 microg x L(-1) and was of the same magnitude as that determined on lung and trachea homogenates. CC16 was also detectable in amniotic fluid with a mean value of 800 microg x L(-1) before delivery. Damage of Clara cells produced by methylcyclopentadienyl manganese tricarbonyl resulted in a significant decrease of CC16 in BALF but did not affect the serum levels of the protein. The nephrotoxicant sodium chromate by contrast had no influence on the CC16 content of BALF but markedly increased CC16 levels in both serum and urine as a result of impaired glomerular filtration and tubular reabsorption, respectively. In conclusion, mouse or rat Clara cell protein of 16-17 kDa can easily be quantified, not only in bronchoalveolar lavage fluid, but also in extrapulmonary fluids such as serum or urine. Thus, in rodents, Clara cell protein of 16-17 kDa follows the same metabolic pathway as in humans, diffusing from the respiratory tract into serum where it is eliminated by the kidneys. This serum Clara cell protein of 16-17 kDa may be useful as a peripheral marker of events taking place in the respiratory tract."
1235602,Tanigawa et al. 1998,"Effects of smoking, aromatic amines, and chromates on CD4+ and CD8+ T lymphocytes in male workers","To investigate effects of smoking, aromatic amines (AAs), and chromates (CRs) on T lymphocyte subpopulations, we measured CD3+, CD4+, and CD8+ T lymphocytes in the peripheral blood of 33 nonexposed workers, 25 AA-use workers, 27 AA-production workers, and 19 CR workers (all subjects were males). The number of CD4+ T lymphocytes in smokers of nonexposed workers was significantly larger than that of the nonsmokers; also, the numbers of CD4+ and CD3+ T lymphocytes in smokers of each group of AA-production and AA-use workers were significantly larger than those in nonsmokers. Number of CD4+ and CD3+ T lymphocytes in nonsmokers of AA-production and CR workers were significantly smaller than those in nonsmokers of nonexposed workers; the number of CD8+ T lymphocytes in nonsmokers of CR workers was significantly smaller than that in nonsmokers of nonexposed workers. The cross-sectional study suggests that (1) smoking increases CD4+ (and CD3+) T lymphocytes in all categories of workers except for CR workers; (2) exposure to CRs and AAs decreases CD4+ (and CD3+) T lymphocytes; (3) the magnitude of decrease in CD4+ T lymphocytes is large among CR workers, intermediate among AA-production workers, and small among AA-use workers regardless of smoking status; and (4) exposure to CRs also decreases CD8+ T lymphocytes.","Effects of smoking, aromatic amines, and chromates on CD4+ and CD8+ T lymphocytes in male workers Abs: To investigate effects of smoking, aromatic amines (AAs), and chromates (CRs) on T lymphocyte subpopulations, we measured CD3+, CD4+, and CD8+ T lymphocytes in the peripheral blood of 33 nonexposed workers, 25 AA-use workers, 27 AA-production workers, and 19 CR workers (all subjects were males). The number of CD4+ T lymphocytes in smokers of nonexposed workers was significantly larger than that of the nonsmokers; also, the numbers of CD4+ and CD3+ T lymphocytes in smokers of each group of AA-production and AA-use workers were significantly larger than those in nonsmokers. Number of CD4+ and CD3+ T lymphocytes in nonsmokers of AA-production and CR workers were significantly smaller than those in nonsmokers of nonexposed workers; the number of CD8+ T lymphocytes in nonsmokers of CR workers was significantly smaller than that in nonsmokers of nonexposed workers. The cross-sectional study suggests that (1) smoking increases CD4+ (and CD3+) T lymphocytes in all categories of workers except for CR workers; (2) exposure to CRs and AAs decreases CD4+ (and CD3+) T lymphocytes; (3) the magnitude of decrease in CD4+ T lymphocytes is large among CR workers, intermediate among AA-production workers, and small among AA-use workers regardless of smoking status; and (4) exposure to CRs also decreases CD8+ T lymphocytes."
1235600,Holmes et al. 1998,Development of a model for classification of toxin-induced lesions using 1H NMR spectroscopy of urine combined with pattern recognition,"Pattern recognition approaches were developed and applied to the classification of 600 MHz 1H NMR spectra of urine from rats dosed with compounds that induced organ-specific damage in either the liver or kidney. Male rats were separated into groups (n = 5) and each treated with one of the following compounds; adriamycin, allyl alcohol, 2-bromoethanamine hydrobromide, hexachlorobutadiene, hydrazine, lead acetate, mercury II chloride, puromycin aminonucleoside, sodium chromate, thioacetamide, 1,1,2-trichloro-3,3,3-trifluoro-1-propene or dose vehicle. Urine samples were collected over a 7 day time-course and analysed using 600 MHz 1H NMR spectroscopy. Each NMR spectrum was data-reduced to provide 256 intensity-related descriptors of the spectra. Data corresponding to the periods 8-24 h, 24-32 h and 32-56 h post-dose were first analysed using principal components analysis (PCA). In addition, samples obtained 120-144 h following the administration of adriamycin and puromycin were included in the analysis in order to compensate for the late onset of glomerular toxicity. Having established that toxin-related clustering behaviour could be detected in the first three principal components (PCs), three-quarters of the data were used to construct a soft independent modelling of class analogy (SIMCA) model. The remainder of the data were used as a test set of the model. Only three out of 61 samples in the test set were misclassified. Finally as a further test of the model, data from the 1H NMR spectra of urine from rats that had been treated with uranyl nitrate were used. Successful prediction of the toxicity type of the compound was achieved based on NMR urinalysis data confirming the robust nature of the derived model.","Development of a model for classification of toxin-induced lesions using 1H NMR spectroscopy of urine combined with pattern recognition Abs: Pattern recognition approaches were developed and applied to the classification of 600 MHz 1H NMR spectra of urine from rats dosed with compounds that induced organ-specific damage in either the liver or kidney. Male rats were separated into groups (n = 5) and each treated with one of the following compounds; adriamycin, allyl alcohol, 2-bromoethanamine hydrobromide, hexachlorobutadiene, hydrazine, lead acetate, mercury II chloride, puromycin aminonucleoside, sodium chromate, thioacetamide, 1,1,2-trichloro-3,3,3-trifluoro-1-propene or dose vehicle. Urine samples were collected over a 7 day time-course and analysed using 600 MHz 1H NMR spectroscopy. Each NMR spectrum was data-reduced to provide 256 intensity-related descriptors of the spectra. Data corresponding to the periods 8-24 h, 24-32 h and 32-56 h post-dose were first analysed using principal components analysis (PCA). In addition, samples obtained 120-144 h following the administration of adriamycin and puromycin were included in the analysis in order to compensate for the late onset of glomerular toxicity. Having established that toxin-related clustering behaviour could be detected in the first three principal components (PCs), three-quarters of the data were used to construct a soft independent modelling of class analogy (SIMCA) model. The remainder of the data were used as a test set of the model. Only three out of 61 samples in the test set were misclassified. Finally as a further test of the model, data from the 1H NMR spectra of urine from rats that had been treated with uranyl nitrate were used. Successful prediction of the toxicity type of the compound was achieved based on NMR urinalysis data confirming the robust nature of the derived model."
1235599,De Tata et al. 1998,Glycated plasma proteins in experimentally induced acute toxic renal failure by dichromate injection: evidence for loss with urine and decreased plasma levels,"In the rat, a single subcutaneous injection of sodium dichromate (20 mg/kg) causes acute renal injury and significant polyuria, proteinuria, and glycosuria (peaking 2-3 days after treatment, and returning to normal by day 5) without any changes in the plasma levels of protein, glucose, and glycated haemoglobin. Surprisingly, the percentage levels of glycated plasma total proteins and albumin (assayed by boronate affinity chromatography) transiently and significantly decrease during recovery from proteinuria (days 4 and 10 after treatment) and were found in the normal range of values by day 18. These changes are concomitant with a significant increase in the percentage level of glycated albumin in urine. Constancy of total plasma protein and the temporal pattern of levels of glycation suggest that changes in the percentage values of glycated proteins are secondary to a transient selective loss of glycated plasma proteins in urine.","Glycated plasma proteins in experimentally induced acute toxic renal failure by dichromate injection: evidence for loss with urine and decreased plasma levels Abs: In the rat, a single subcutaneous injection of sodium dichromate (20 mg/kg) causes acute renal injury and significant polyuria, proteinuria, and glycosuria (peaking 2-3 days after treatment, and returning to normal by day 5) without any changes in the plasma levels of protein, glucose, and glycated haemoglobin. Surprisingly, the percentage levels of glycated plasma total proteins and albumin (assayed by boronate affinity chromatography) transiently and significantly decrease during recovery from proteinuria (days 4 and 10 after treatment) and were found in the normal range of values by day 18. These changes are concomitant with a significant increase in the percentage level of glycated albumin in urine. Constancy of total plasma protein and the temporal pattern of levels of glycation suggest that changes in the percentage values of glycated proteins are secondary to a transient selective loss of glycated plasma proteins in urine."
1235597,Appenroth and  Winnefeld 1998,Vitamin E and C in the prevention of metal nephrotoxicity in developing rats,The protective effect of vitamin E and C on sodium chromate (Cr) and thallium (Tl) induced nephrotoxicity was tested in 10- and 55-day-old rats. The concentrations of Cr and Tl were determined in renal cortex and medulla by atomic absorption spectrometry. Urinary volume and protein excretion as well as blood urea nitrogen (BUN) concentration were determined as parameters of nephrotoxicity. Cr and Tl induced nephrotoxicity was significantly more expressed in adult than in young rats. In Cr and Tl nephrotoxicity the protective effect of vitamin E was evident in both age groups. Vitamin E decreased Tl concentration in renal tissue. Therefore its protective effect is not to be attributed to its known antioxidant effect but to lower Tl concentration in renal tissue. Vitamin C was protective in Cr and Tl induced nephrotoxicity in adult rats without influence on metal concentrations in renal tissue. The dose necessary for protection against toxic Cr action in adult rats was not tolerated by young rats. The combined administration of both vitamins abolished the protective effect against Cr nephrotoxicity of the administration of each vitamin alone in adult rats. When vitamin E and C were administered in Tl treated adult and young rats the protective effect was the same as after the administration of each vitamin alone. Possible mechanisms are discussed.,Vitamin E and C in the prevention of metal nephrotoxicity in developing rats Abs: The protective effect of vitamin E and C on sodium chromate (Cr) and thallium (Tl) induced nephrotoxicity was tested in 10- and 55-day-old rats. The concentrations of Cr and Tl were determined in renal cortex and medulla by atomic absorption spectrometry. Urinary volume and protein excretion as well as blood urea nitrogen (BUN) concentration were determined as parameters of nephrotoxicity. Cr and Tl induced nephrotoxicity was significantly more expressed in adult than in young rats. In Cr and Tl nephrotoxicity the protective effect of vitamin E was evident in both age groups. Vitamin E decreased Tl concentration in renal tissue. Therefore its protective effect is not to be attributed to its known antioxidant effect but to lower Tl concentration in renal tissue. Vitamin C was protective in Cr and Tl induced nephrotoxicity in adult rats without influence on metal concentrations in renal tissue. The dose necessary for protection against toxic Cr action in adult rats was not tolerated by young rats. The combined administration of both vitamins abolished the protective effect against Cr nephrotoxicity of the administration of each vitamin alone in adult rats. When vitamin E and C were administered in Tl treated adult and young rats the protective effect was the same as after the administration of each vitamin alone. Possible mechanisms are discussed.
1235593,Chang et al. 1999,Rat gastrointestinal motor responses mediated via activation of neurokinin receptors,"Natural neurokinins (NK) and their specific receptor agonists, including substance P (SP), neurokinin A (NKA), neurokinin B (NKB), septide, [NIe10]-NKA4-10 and senktide, were used to assess whether they could activate established NK receptors in rat gastrointestinal tract and central nervous system to alter gastric emptying or intestinal transit. Fasting rats were intubated with an orogastric catheter to feed them liquid radiochromium. Neurokinins and analogues (at 10(-10), 10(-9), 10(-8) and 10(-7) mol/kg) and vehicle (saline + 0.1% bovine serum albumin) were injected via an intraperitoneal route. Rats were killed 15 min later and the whole gut was removed. The radioactivity of the stomach and 10 equally divided small intestinal segments was counted to determine gastric emptying and the geometric centre of intestinal transit. Septide treatment at 10(-8) and 10(-7) mol/kg markedly delayed gastric emptying. All doses of NKA inhibited gastric emptying. However, other peptides did not influence gastric emptying. Both septide and NKB treatment at 10(-8) and 10(-7) mol/kg enhanced intestinal transit. Substance P or senktide treatment (10-(-7) mol/kg) also enhanced intestinal transit. Stasis of remaining radioactivity in the proximal intestine was found following SP, septide, NKA and NKB treatment, whereas accelerated transit in the distal intestine was induced following NKA, NKB and senktide treatment. In conclusion, the in vivo study of NK and their specific agonists manifests a selective influence of these compounds on rat gastrointestinal tract. This selective activation of stomach NK1 and NK2 receptors delays gastric emptying, whereas activation of intestinal NK1 and NK3 receptors enhances intestinal transit.","Rat gastrointestinal motor responses mediated via activation of neurokinin receptors Abs: Natural neurokinins (NK) and their specific receptor agonists, including substance P (SP), neurokinin A (NKA), neurokinin B (NKB), septide, [NIe10]-NKA4-10 and senktide, were used to assess whether they could activate established NK receptors in rat gastrointestinal tract and central nervous system to alter gastric emptying or intestinal transit. Fasting rats were intubated with an orogastric catheter to feed them liquid radiochromium. Neurokinins and analogues (at 10(-10), 10(-9), 10(-8) and 10(-7) mol/kg) and vehicle (saline + 0.1% bovine serum albumin) were injected via an intraperitoneal route. Rats were killed 15 min later and the whole gut was removed. The radioactivity of the stomach and 10 equally divided small intestinal segments was counted to determine gastric emptying and the geometric centre of intestinal transit. Septide treatment at 10(-8) and 10(-7) mol/kg markedly delayed gastric emptying. All doses of NKA inhibited gastric emptying. However, other peptides did not influence gastric emptying. Both septide and NKB treatment at 10(-8) and 10(-7) mol/kg enhanced intestinal transit. Substance P or senktide treatment (10-(-7) mol/kg) also enhanced intestinal transit. Stasis of remaining radioactivity in the proximal intestine was found following SP, septide, NKA and NKB treatment, whereas accelerated transit in the distal intestine was induced following NKA, NKB and senktide treatment. In conclusion, the in vivo study of NK and their specific agonists manifests a selective influence of these compounds on rat gastrointestinal tract. This selective activation of stomach NK1 and NK2 receptors delays gastric emptying, whereas activation of intestinal NK1 and NK3 receptors enhances intestinal transit."
1235591,Singh et al. 1998,Sensitive quantitation of chromium-DNA adducts by inductively coupled plasma mass spectrometry with a direct injection high-efficiency nebulizer,"A novel method is described for the sensitive detection of chromium-DNA adducts. Chromium-DNA adducts were determined in 1 microgram of DNA from normal human lung fibroblasts exposed to sodium chromate using microscale flow injection analysis with a direct injection high-efficiency nebulizer and inductively coupled plasma mass spectrometry detection. The frequency of Cr-DNA adducts increased in a dose-dependent sigmoidal manner, indicating saturation and toxicity. The low detection limits (on the order of parts per trillion) allows the detection of as few as two Cr adducts per 10,000 bases, which, coupled with the small DNA sample requirement, makes this technique suitable for measuring metal-DNA adducts as biomarkers of exposure to toxic and carcinogenic metals such as Cr, in cultured cells, animals, and humans.","Sensitive quantitation of chromium-DNA adducts by inductively coupled plasma mass spectrometry with a direct injection high-efficiency nebulizer Abs: A novel method is described for the sensitive detection of chromium-DNA adducts. Chromium-DNA adducts were determined in 1 microgram of DNA from normal human lung fibroblasts exposed to sodium chromate using microscale flow injection analysis with a direct injection high-efficiency nebulizer and inductively coupled plasma mass spectrometry detection. The frequency of Cr-DNA adducts increased in a dose-dependent sigmoidal manner, indicating saturation and toxicity. The low detection limits (on the order of parts per trillion) allows the detection of as few as two Cr adducts per 10,000 bases, which, coupled with the small DNA sample requirement, makes this technique suitable for measuring metal-DNA adducts as biomarkers of exposure to toxic and carcinogenic metals such as Cr, in cultured cells, animals, and humans."
1235588,Martin et al. 1999,The DNA repair inhibitors hydroxyurea and cytosine arabinoside enhance the sensitivity of the alkaline single-cell gel electrophoresis ('comet') assay in metabolically-competent MCL-5 cells,"We have found previously that the metabolically-competent human MCL-5 cell line did not appear to be usefully sensitive to the DNA-damaging effects of several carcinogens, as measured by the alkaline single-cell gel electrophoresis ('comet') assay. We therefore sought to increase its sensitivity by inhibiting DNA repair during exposure to test compounds, using 10 mM hydroxyurea (HU) and 1.8 mM cytosine arabinoside (ara-C), which inhibit DNA resynthesis during nucleotide excision repair. The following compounds were tested, using a 30-min exposure, in the absence or presence of HU/ara-C: 2-amino-3,8-dimethylimidazo[4,5-f]quinoxaline (8-MeIQx), 2-amino-3,4,8-trimethylimidazo[4,5-f]quinoxaline (4, 8-DiMeIQx), 2-amino-3-methylimidazo[4,5-f]quinoline (IQ), 2-amino-9H-pyrido[2,3-b]indole (A[alpha]C), 2-amino-3-methyl-9H-pyrido[2,3-b]indole (MeA[alpha]C), 2-amino-1-methyl-6-phenylimidazo[4,5-b]pyridine (PhIP), benzo[a]pyrene (B[a]P), 3-methylcholanthrene (3-MCA), 7, 12-dimethylbenz[a]anthracene (DMBA), 1-nitropyrene (1-NP), 2-nitrofluorene (2-NF), aniline, o-toluidine, benzene, lindane, bleomycin, cisplatin, N-methyl-N'-nitro-N-nitrosoguanidine (MNNG), sodium chromate, chromic chloride, and diethylstilboestrol (DES). We made the following observations. The background level of comet formation was reasonably constant over several months and was increased only slightly, but significantly, in the presence of the DNA-repair inhibitors. All compounds that induced comet formation did so without appreciable cytotoxicity as assessed by trypan blue exclusion. Of the compounds tested, the heterocyclic amines and polycyclic aromatic hydrocarbons (with the exceptions of PhIP and B[a]P) failed to induce convincing levels of comet formation in the absence of repair inhibitors. In their presence the heterocyclic amines tested induced comet formation (with the exception of 8-MeIQx), with widely differing potencies. 1-NP failed to elicit marked comet formation even in the presence of HU/ara-C. Aniline and o-toluidine produced significant levels of comet formation in the absence of HU/ara-C, but in their presence comet formation was markedly increased. Benzene, lindane, bleomycin, cisplatin, MNNG, sodium chromate and chromic chloride induced comet formation in the absence of HU/ara-C, but, with the exception of cisplatin, their presence enhanced comet formation. Neither sucrose nor DES elicited comet formation under the conditions used in this study. Many more agents need to be tested in order to determine how well the comet assay using MCL-5 cells (or modified versions of it) can distinguish genotoxins from non-genotoxins.","The DNA repair inhibitors hydroxyurea and cytosine arabinoside enhance the sensitivity of the alkaline single-cell gel electrophoresis ('comet') assay in metabolically-competent MCL-5 cells Abs: We have found previously that the metabolically-competent human MCL-5 cell line did not appear to be usefully sensitive to the DNA-damaging effects of several carcinogens, as measured by the alkaline single-cell gel electrophoresis ('comet') assay. We therefore sought to increase its sensitivity by inhibiting DNA repair during exposure to test compounds, using 10 mM hydroxyurea (HU) and 1.8 mM cytosine arabinoside (ara-C), which inhibit DNA resynthesis during nucleotide excision repair. The following compounds were tested, using a 30-min exposure, in the absence or presence of HU/ara-C: 2-amino-3,8-dimethylimidazo[4,5-f]quinoxaline (8-MeIQx), 2-amino-3,4,8-trimethylimidazo[4,5-f]quinoxaline (4, 8-DiMeIQx), 2-amino-3-methylimidazo[4,5-f]quinoline (IQ), 2-amino-9H-pyrido[2,3-b]indole (A[alpha]C), 2-amino-3-methyl-9H-pyrido[2,3-b]indole (MeA[alpha]C), 2-amino-1-methyl-6-phenylimidazo[4,5-b]pyridine (PhIP), benzo[a]pyrene (B[a]P), 3-methylcholanthrene (3-MCA), 7, 12-dimethylbenz[a]anthracene (DMBA), 1-nitropyrene (1-NP), 2-nitrofluorene (2-NF), aniline, o-toluidine, benzene, lindane, bleomycin, cisplatin, N-methyl-N'-nitro-N-nitrosoguanidine (MNNG), sodium chromate, chromic chloride, and diethylstilboestrol (DES). We made the following observations. The background level of comet formation was reasonably constant over several months and was increased only slightly, but significantly, in the presence of the DNA-repair inhibitors. All compounds that induced comet formation did so without appreciable cytotoxicity as assessed by trypan blue exclusion. Of the compounds tested, the heterocyclic amines and polycyclic aromatic hydrocarbons (with the exceptions of PhIP and B[a]P) failed to induce convincing levels of comet formation in the absence of repair inhibitors. In their presence the heterocyclic amines tested induced comet formation (with the exception of 8-MeIQx), with widely differing potencies. 1-NP failed to elicit marked comet formation even in the presence of HU/ara-C. Aniline and o-toluidine produced significant levels of comet formation in the absence of HU/ara-C, but in their presence comet formation was markedly increased. Benzene, lindane, bleomycin, cisplatin, MNNG, sodium chromate and chromic chloride induced comet formation in the absence of HU/ara-C, but, with the exception of cisplatin, their presence enhanced comet formation. Neither sucrose nor DES elicited comet formation under the conditions used in this study. Many more agents need to be tested in order to determine how well the comet assay using MCL-5 cells (or modified versions of it) can distinguish genotoxins from non-genotoxins."
1235587,Lapuma and  Bolch 1999,The impact of recirculating industrial air on aircraft painting operations,"The 1990 Clean Air Act Amendments resulted in new environmental regulations for hazardous air pollutants. Industries such as painting facilities may have to treat large volumes of air, which increases the cost of an air control system. Recirculating a portion of the air back into the facility is an option to reduce the amount of air to be treated. The authors of this study developed a computer model written in Microsoft Excel 97 to analyze the impact of recirculation on worker safety and compliance costs. The model has a chemical database with over 1300 chemicals. The model will predict indoor air concentrations using mass balance calculations and results are compared to occupational exposure limits. A case study is performed on a C-130 aircraft painting facility at Hill Air Force Base, Utah. The model predicts strontium chromate concentrations found in primer paints will reach 1000 times the exposure limit. Strontium chromate and other solid particulates are nearly unaffected by recirculation because the air is filtered during recirculation. The next highest chemical, hexamethylene diisocyanate, increases from 2.6 to 10.5 times the exposure limit at 0 percent and 75 percent recirculation, respectively. Due to the level of respiratory protection required for the strontium chromate, workers are well protected from the modest increases in concentrations caused by recirculating 75 percent of the air. The initial cost of an air control system is $4.5 million with no recirculation and $1.8 million at 75 percent recirculation. The model is an excellent tool to evaluate air control options with a focus on worker safety. In the case study, the model highlights strontium chromate primers as good candidates for substitution. The model shows that recirculating 75 percent of the air at the Hill painting facility has a negligible impact on safety and could save $2.7 million on the initial expenses of a thermal treatment system.","The impact of recirculating industrial air on aircraft painting operations Abs: The 1990 Clean Air Act Amendments resulted in new environmental regulations for hazardous air pollutants. Industries such as painting facilities may have to treat large volumes of air, which increases the cost of an air control system. Recirculating a portion of the air back into the facility is an option to reduce the amount of air to be treated. The authors of this study developed a computer model written in Microsoft Excel 97 to analyze the impact of recirculation on worker safety and compliance costs. The model has a chemical database with over 1300 chemicals. The model will predict indoor air concentrations using mass balance calculations and results are compared to occupational exposure limits. A case study is performed on a C-130 aircraft painting facility at Hill Air Force Base, Utah. The model predicts strontium chromate concentrations found in primer paints will reach 1000 times the exposure limit. Strontium chromate and other solid particulates are nearly unaffected by recirculation because the air is filtered during recirculation. The next highest chemical, hexamethylene diisocyanate, increases from 2.6 to 10.5 times the exposure limit at 0 percent and 75 percent recirculation, respectively. Due to the level of respiratory protection required for the strontium chromate, workers are well protected from the modest increases in concentrations caused by recirculating 75 percent of the air. The initial cost of an air control system is $4.5 million with no recirculation and $1.8 million at 75 percent recirculation. The model is an excellent tool to evaluate air control options with a focus on worker safety. In the case study, the model highlights strontium chromate primers as good candidates for substitution. The model shows that recirculating 75 percent of the air at the Hill painting facility has a negligible impact on safety and could save $2.7 million on the initial expenses of a thermal treatment system."
1235585,Casadevall et al. 1999,Chromium(VI)-mediated DNA damage: oxidative pathways resulting in the formation of DNA breaks and abasic sites,"Inside cells chromium(VI) is activated to its ultimate carcinogenic form by reducing agents including glutathione (GSH) and ascorbate (AsA). The precise mechanism by which DNA damaging species are formed is unclear. In earlier in vitro work with isolated DNA we have shown that chromium(VI) in combination with GSH or AsA is able to induce similar numbers of single strand breaks and apurinic/apyrimidinic sites (AP-sites). Moreover, the formation of both lesions followed a similar temporal pattern. It is conceivable that the two forms of DNA damage arise from a common precursor lesion (e.g. hydrogen abstraction at C4' of the DNA sugar moiety) with a partitioning along two pathways, one yielding an AP-site, the other a single strand break (SSB) and a base propenal. The present study is intended to test this hypothesis by analysing whether oxidation products of deoxyribose can be formed in the presence of chromium(VI) and GSH or AsA. It was found that mixtures of chromium(VI) and GSH or AsA were able to oxidise 2-deoxyribose to yield malondialdehyde, which was detected by reaction with thiobarbituric acid. The characteristic pink chromogen, which forms upon reaction with thiobarbituric acid, was also observed with calf thymus DNA as the substrate. In both experimental systems the addition of catalase prevented the formation of deoxyribose breakdown products. Hydroxyl radicals did not seem to be important for the generation of DNA damage as the characteristic modified DNA bases could not be detected by using gas chromatography-mass spectrometry. These results lead us to conclude that the formation of SSB during the reductive conversion of chromium(VI) proceeds primarily via hydrogen abstraction from C4'. The observation that Fenton chemistry is not involved in these processes is intriguing and necessitates further research into the ways in which chromium can activate molecular oxygen to form DNA damaging species.","Chromium(VI)-mediated DNA damage: oxidative pathways resulting in the formation of DNA breaks and abasic sites Abs: Inside cells chromium(VI) is activated to its ultimate carcinogenic form by reducing agents including glutathione (GSH) and ascorbate (AsA). The precise mechanism by which DNA damaging species are formed is unclear. In earlier in vitro work with isolated DNA we have shown that chromium(VI) in combination with GSH or AsA is able to induce similar numbers of single strand breaks and apurinic/apyrimidinic sites (AP-sites). Moreover, the formation of both lesions followed a similar temporal pattern. It is conceivable that the two forms of DNA damage arise from a common precursor lesion (e.g. hydrogen abstraction at C4' of the DNA sugar moiety) with a partitioning along two pathways, one yielding an AP-site, the other a single strand break (SSB) and a base propenal. The present study is intended to test this hypothesis by analysing whether oxidation products of deoxyribose can be formed in the presence of chromium(VI) and GSH or AsA. It was found that mixtures of chromium(VI) and GSH or AsA were able to oxidise 2-deoxyribose to yield malondialdehyde, which was detected by reaction with thiobarbituric acid. The characteristic pink chromogen, which forms upon reaction with thiobarbituric acid, was also observed with calf thymus DNA as the substrate. In both experimental systems the addition of catalase prevented the formation of deoxyribose breakdown products. Hydroxyl radicals did not seem to be important for the generation of DNA damage as the characteristic modified DNA bases could not be detected by using gas chromatography-mass spectrometry. These results lead us to conclude that the formation of SSB during the reductive conversion of chromium(VI) proceeds primarily via hydrogen abstraction from C4'. The observation that Fenton chemistry is not involved in these processes is intriguing and necessitates further research into the ways in which chromium can activate molecular oxygen to form DNA damaging species."
1235584,Yao et al. 2000,Foreign metallothionein-I expression by transient transfection in MT-I and MT-II null astrocytes confers increased protection against acute methylmercury cytotoxicity,"The mechanisms associated with metallothionein (MT) gene regulation are complex and poorly understood. Only a modest increase in brain MT expression levels is attained by exposure to metals, MT gene transfection, and MT gene knock-in techniques. Accordingly, in the present study, MT null astrocytes isolated from transgenic mice deficient in MT-I and MT-II genes were introduced as a zero background model of MT expression. MT protein levels were determined by western blot analysis. MT proteins in MT-I and MT-II null astrocytes were undetectable. Transient MT-I gene transfection increased the levels of foreign MT expression in MT-I and MT-II null astrocytes by 2.3-fold above basal levels in wild-type astrocytes. Intracellular Na(2)51CrO(4) efflux and D-[2,3-3H]aspartate uptake were studied as indices of acute methylmercury (MeHg) (5 microM) cytotoxicity. In MT-I and MT-II knockout astrocytes MeHg led to significant (p&lt;0.01) increase in Na(2)51CrO(4) efflux and a significant (p&lt;0.05) decrease in the initial rate (1 min) of D-[2, 3-3H]aspartate uptake compared to MT-I and MT-II knockout controls. Transfection of the MT-I gene in MT-I and MT-II null mice significantly (p&lt;0.01) decreased the effect of MeHg on Na(2)51CrO(4) efflux in MT null, as well as wild-type astrocytes. MT-I gene transfection in MT-I and MT-II null astrocytes reversed the inhibitory effect of MeHg on D-[2,3-3H]aspartate uptake, such that initial rates of uptake in MT-I transfected cells in the presence and absence of MeHg (5 microM) were indistinguishable. These results demonstrate that: (1) astrocytes lacking MTs are more sensitive to MeHg than those with basal MT protein levels, (2) the MT-I gene can be overexpressed in MT-I and MT-II null astrocytes by transient MT-I gene transfection, and (3) that foreign MT expression endows astrocytes with increased resistance to MeHg.","Foreign metallothionein-I expression by transient transfection in MT-I and MT-II null astrocytes confers increased protection against acute methylmercury cytotoxicity Abs: The mechanisms associated with metallothionein (MT) gene regulation are complex and poorly understood. Only a modest increase in brain MT expression levels is attained by exposure to metals, MT gene transfection, and MT gene knock-in techniques. Accordingly, in the present study, MT null astrocytes isolated from transgenic mice deficient in MT-I and MT-II genes were introduced as a zero background model of MT expression. MT protein levels were determined by western blot analysis. MT proteins in MT-I and MT-II null astrocytes were undetectable. Transient MT-I gene transfection increased the levels of foreign MT expression in MT-I and MT-II null astrocytes by 2.3-fold above basal levels in wild-type astrocytes. Intracellular Na(2)51CrO(4) efflux and D-[2,3-3H]aspartate uptake were studied as indices of acute methylmercury (MeHg) (5 microM) cytotoxicity. In MT-I and MT-II knockout astrocytes MeHg led to significant (p&lt;0.01) increase in Na(2)51CrO(4) efflux and a significant (p&lt;0.05) decrease in the initial rate (1 min) of D-[2, 3-3H]aspartate uptake compared to MT-I and MT-II knockout controls. Transfection of the MT-I gene in MT-I and MT-II null mice significantly (p&lt;0.01) decreased the effect of MeHg on Na(2)51CrO(4) efflux in MT null, as well as wild-type astrocytes. MT-I gene transfection in MT-I and MT-II null astrocytes reversed the inhibitory effect of MeHg on D-[2,3-3H]aspartate uptake, such that initial rates of uptake in MT-I transfected cells in the presence and absence of MeHg (5 microM) were indistinguishable. These results demonstrate that: (1) astrocytes lacking MTs are more sensitive to MeHg than those with basal MT protein levels, (2) the MT-I gene can be overexpressed in MT-I and MT-II null astrocytes by transient MT-I gene transfection, and (3) that foreign MT expression endows astrocytes with increased resistance to MeHg."
1235583,Korkmaz 2000,In vitro effects of sodium fluoride and sodium dichromate on dynamic properties of human erythrocyte membrane,"Sodium fluoride (NaF) and sodium dichromate (Na2Cr2O7) are two different toxic compounds which are used as a dental caries prophylactic and as an oxidising agent in various industrial areas, respectively. However, accidental fluoride and chromate poisoning is not a rare occurrence, even death may result from cardiac or respiratory failure. In the present work, alterations produced by NaF, Na2Cr2O7 and temperature changes in the molecular dynamics of the human erythrocyte membrane were studied, in vitro, by the spin-labelling ESR technique. Human intact erythrocyte cells spin labelled with 5- and 16-doxyl stearic acids (5-DSA and 16-DSA) and treated with 40 microM NaF and 5 microM Na2Cr2O7 at 37 degrees C were used to quantify membrane fluidity. This was performed by measuring the changes in the order parameter (S), correlation time (tau) and phase transition temperature using recorded electron spin resonance (ESR) spectra. Experimental results show that 5 microM Na2Cr2O7 and 40 microM NaF do not produce any significant effects on the order parameter of 5-DSA spin label while they cause appreciable changes in the correlation time of the same label. As for 16-DSA, while Na2Cr2O7 does not produce any measurable effect on the order parameter of this label, NaF does in a certain extent. Although weak, the effects of both compounds on the correlation time of 16-DSA are found to be well above the experimental error limits. Change in temperature was observed to alter significantly S and tau parameters which show biphasic character in the temperature range of 5-50 degrees C. Activation energies of the hydrocarbon chains above and below transition temperatures were also determined for untreated and NaF or Na2Cr2O7 treated erythrocyte cells and the effect of NaF and Na2Cr2O7 on these energies and transition temperatures were discussed.","In vitro effects of sodium fluoride and sodium dichromate on dynamic properties of human erythrocyte membrane Abs: Sodium fluoride (NaF) and sodium dichromate (Na2Cr2O7) are two different toxic compounds which are used as a dental caries prophylactic and as an oxidising agent in various industrial areas, respectively. However, accidental fluoride and chromate poisoning is not a rare occurrence, even death may result from cardiac or respiratory failure. In the present work, alterations produced by NaF, Na2Cr2O7 and temperature changes in the molecular dynamics of the human erythrocyte membrane were studied, in vitro, by the spin-labelling ESR technique. Human intact erythrocyte cells spin labelled with 5- and 16-doxyl stearic acids (5-DSA and 16-DSA) and treated with 40 microM NaF and 5 microM Na2Cr2O7 at 37 degrees C were used to quantify membrane fluidity. This was performed by measuring the changes in the order parameter (S), correlation time (tau) and phase transition temperature using recorded electron spin resonance (ESR) spectra. Experimental results show that 5 microM Na2Cr2O7 and 40 microM NaF do not produce any significant effects on the order parameter of 5-DSA spin label while they cause appreciable changes in the correlation time of the same label. As for 16-DSA, while Na2Cr2O7 does not produce any measurable effect on the order parameter of this label, NaF does in a certain extent. Although weak, the effects of both compounds on the correlation time of 16-DSA are found to be well above the experimental error limits. Change in temperature was observed to alter significantly S and tau parameters which show biphasic character in the temperature range of 5-50 degrees C. Activation energies of the hydrocarbon chains above and below transition temperatures were also determined for untreated and NaF or Na2Cr2O7 treated erythrocyte cells and the effect of NaF and Na2Cr2O7 on these energies and transition temperatures were discussed."
1235582,Demirci and  Pometto III 2000,Enhanced organically bound chromium yeast production,"This paper describes continuous and fed-batch fermentation protocols for enhanced production of organically bound chromium yeast. During continuous fermentation, several inorganic chromium compounds were evaluated. Sodium chromate demonstrated the best chromium incorporation into yeast biomass without any precipitation in the fermentation medium. During fed-batch fermentation, several sodium chromate concentrations were evaluated at 1.1, 3.5, 5.9, 7.1, 8.3, and 10.8 g/L with continuous or single-dose addition. For single-dose addition of sodium chromate, some precipitation was observed for all concentrations, which reduced the available chromium in the fermentation medium. Adapted strain C11-1, obtained during continuous fermentation, produced higher biomass than the wild type but significantly lowered chromium incorporation. Pilot-scale fermentation demonstrated similar total chromium incorporation (2966 ppm) with lower biomass production compared to benchtop fermentation performed at the same sodium chromate addition.","Enhanced organically bound chromium yeast production Abs: This paper describes continuous and fed-batch fermentation protocols for enhanced production of organically bound chromium yeast. During continuous fermentation, several inorganic chromium compounds were evaluated. Sodium chromate demonstrated the best chromium incorporation into yeast biomass without any precipitation in the fermentation medium. During fed-batch fermentation, several sodium chromate concentrations were evaluated at 1.1, 3.5, 5.9, 7.1, 8.3, and 10.8 g/L with continuous or single-dose addition. For single-dose addition of sodium chromate, some precipitation was observed for all concentrations, which reduced the available chromium in the fermentation medium. Adapted strain C11-1, obtained during continuous fermentation, produced higher biomass than the wild type but significantly lowered chromium incorporation. Pilot-scale fermentation demonstrated similar total chromium incorporation (2966 ppm) with lower biomass production compared to benchtop fermentation performed at the same sodium chromate addition."
1235581,Diamantino et al. 2000,"Toxicity of sodium molybdate and sodium dichromate to Daphnia magna straus evaluated in acute, chronic, and acetylcholinesterase inhibition tests","As a result of a widespread application in numerous industrial processes, chromium is a contaminant of many environmental systems. Chromium and their compounds are toxic to both invertebrates and vertebrates and, for this reason, there has been a search for suitable and less toxic alternatives. Molybdenum compounds have been studied as alternative to chromium compounds for some industrial applications. The toxicity of chromium is well known but the effects of molybdenum and molybdenum mining on natural populations and communities of freshwater invertebrates have not often been studied. However, chromium, and molybdenum (and their compounds) are included in the same list (List II) of European Union dangerous substances. In this study, the acute and chronic effects of sodium molybdate and sodium dichromate to Daphnia magna Straus were evaluated. Furthermore, in vitro and in vivo effects of these two metals on acetylcholinesterase (AChE) activity of D. magna Straus were investigated. LC(50) values determined at 48 h were 0.29 and 2847.5 mg L(-1) for chromium (as sodium dichromate) and molybdenum (as sodium molybdate), respectively. No significant in vitro effects of both metals on AChE were found. However, both toxicants inhibited AChE in vivo at concentrations under the respective 48-h LC(50) values. Both sodium dichromate and sodium molybdate inhibited the reproduction and growth of D. magna, but the concentrations inducing significant effects were different for the two chemicals. Sodium molybdate had significant lower toxicity to D. magna Straus than sodium dichromate.","Toxicity of sodium molybdate and sodium dichromate to Daphnia magna straus evaluated in acute, chronic, and acetylcholinesterase inhibition tests Abs: As a result of a widespread application in numerous industrial processes, chromium is a contaminant of many environmental systems. Chromium and their compounds are toxic to both invertebrates and vertebrates and, for this reason, there has been a search for suitable and less toxic alternatives. Molybdenum compounds have been studied as alternative to chromium compounds for some industrial applications. The toxicity of chromium is well known but the effects of molybdenum and molybdenum mining on natural populations and communities of freshwater invertebrates have not often been studied. However, chromium, and molybdenum (and their compounds) are included in the same list (List II) of European Union dangerous substances. In this study, the acute and chronic effects of sodium molybdate and sodium dichromate to Daphnia magna Straus were evaluated. Furthermore, in vitro and in vivo effects of these two metals on acetylcholinesterase (AChE) activity of D. magna Straus were investigated. LC(50) values determined at 48 h were 0.29 and 2847.5 mg L(-1) for chromium (as sodium dichromate) and molybdenum (as sodium molybdate), respectively. No significant in vitro effects of both metals on AChE were found. However, both toxicants inhibited AChE in vivo at concentrations under the respective 48-h LC(50) values. Both sodium dichromate and sodium molybdate inhibited the reproduction and growth of D. magna, but the concentrations inducing significant effects were different for the two chemicals. Sodium molybdate had significant lower toxicity to D. magna Straus than sodium dichromate."
1235579,Fernandes et al. 2000,"Chromate-induced human erythrocytes haemoglobin oxidation and peroxidation: influence of vitamin E, vitamin C, salicylate, deferoxamine, and N-ethylmaleimide","In order to attenuate or to prevent chromate-induced human erythrocytes injury, the influence of vitamin E, vitamin C, salicylate, deferoxamine, and N-ethylmaleimide on chromate-induced human erythrocytes haemoglobin oxidation and peroxidation were investigated. It was observed that pretreatment of human erythrocytes with vitamin E (20 microM), vitamin C (1 mM), salicylate (3 mM), and deferoxamine (4 mM) significantly increased (P=0.0001) chromate-induced human erythrocytes haemoglobin oxidation in a time dependent manner, while it was significantly decreased (P=0.0001) by pretreatment with N-ethylmaleimide (1 mM). In contrast, pretreatment of human erythrocytes with deferoxamine (4 mM) immediately inhibited (P=0.0001) chromate-induced human erythrocytes peroxidation, while it was significantly increased (P=0.0001) by pretreatment with N-ethylmaleimide (1 mM) during the first 4 h of cells exposition to chromate. For time periods superior to 6 h pretreatment with N-ethylmaleimide (1 mM) significantly decreased (P=0.0001) chromate-induced human erythrocytes peroxidation. It was concluded that care must be taken as these drugs are used to prevent against toxicity induced by chromium(VI) compounds.","Chromate-induced human erythrocytes haemoglobin oxidation and peroxidation: influence of vitamin E, vitamin C, salicylate, deferoxamine, and N-ethylmaleimide Abs: In order to attenuate or to prevent chromate-induced human erythrocytes injury, the influence of vitamin E, vitamin C, salicylate, deferoxamine, and N-ethylmaleimide on chromate-induced human erythrocytes haemoglobin oxidation and peroxidation were investigated. It was observed that pretreatment of human erythrocytes with vitamin E (20 microM), vitamin C (1 mM), salicylate (3 mM), and deferoxamine (4 mM) significantly increased (P=0.0001) chromate-induced human erythrocytes haemoglobin oxidation in a time dependent manner, while it was significantly decreased (P=0.0001) by pretreatment with N-ethylmaleimide (1 mM). In contrast, pretreatment of human erythrocytes with deferoxamine (4 mM) immediately inhibited (P=0.0001) chromate-induced human erythrocytes peroxidation, while it was significantly increased (P=0.0001) by pretreatment with N-ethylmaleimide (1 mM) during the first 4 h of cells exposition to chromate. For time periods superior to 6 h pretreatment with N-ethylmaleimide (1 mM) significantly decreased (P=0.0001) chromate-induced human erythrocytes peroxidation. It was concluded that care must be taken as these drugs are used to prevent against toxicity induced by chromium(VI) compounds."
1235577,Kubota et al. 2000,Effect of hemostatics used during operations for digestive organ on cancer cells present in the peritoneal cavity,"We investigated effects of hemostatics used during operations for digestive organ on cancer cells present in the peritoneal cavity using BALB/c mice inoculated with Meth A tumor cells (fibrosarcoma) intraperitoneally (i.p.) and C3H/He mice inoculated with MH134 tumor cell (hepatic cell carcinoma) i.p. Microfibrillar collagen hemostat (Avitene) or fibrinogen preparation (Beriplast P) did not affect survivals of those tumor-bearing mice. Gelatin sponge (Spongel)prolonged survivals of MH134 tumor-bearing mice. Liquid form gelatin used instead of Spongel displayed in vitro antitumor effect on MH134 tumor cells at the concentration of 15 mg/ml. Radioactive sodium chromate-labeled MH134 and Meth A tumor cells were not lysed when they were incubated with 15 mg/ml of liquid form gelatin for 24 hours. On the other hand, the tritium thymidine (3H-TdR) uptake by MH134 or RL male 1 tumor cells was suppressed when they were incubated with 15 mg/ml of liquid form gelatin for 24 hours. Proliferation of Meth A tumor cells were not affected by the treatment. Effect of liquid form gelatin on phytohemagglutinin (PHA)-stimulated spleen cells as a benign counter-part of RL male 1 tumor cells (T cell lymphoma) was examined. Liquid form gelatin (15 mg/ml) did not suppress 3H-TdR uptake by PHA-stimulated spleen cells.","Effect of hemostatics used during operations for digestive organ on cancer cells present in the peritoneal cavity Abs: We investigated effects of hemostatics used during operations for digestive organ on cancer cells present in the peritoneal cavity using BALB/c mice inoculated with Meth A tumor cells (fibrosarcoma) intraperitoneally (i.p.) and C3H/He mice inoculated with MH134 tumor cell (hepatic cell carcinoma) i.p. Microfibrillar collagen hemostat (Avitene) or fibrinogen preparation (Beriplast P) did not affect survivals of those tumor-bearing mice. Gelatin sponge (Spongel)prolonged survivals of MH134 tumor-bearing mice. Liquid form gelatin used instead of Spongel displayed in vitro antitumor effect on MH134 tumor cells at the concentration of 15 mg/ml. Radioactive sodium chromate-labeled MH134 and Meth A tumor cells were not lysed when they were incubated with 15 mg/ml of liquid form gelatin for 24 hours. On the other hand, the tritium thymidine (3H-TdR) uptake by MH134 or RL male 1 tumor cells was suppressed when they were incubated with 15 mg/ml of liquid form gelatin for 24 hours. Proliferation of Meth A tumor cells were not affected by the treatment. Effect of liquid form gelatin on phytohemagglutinin (PHA)-stimulated spleen cells as a benign counter-part of RL male 1 tumor cells (T cell lymphoma) was examined. Liquid form gelatin (15 mg/ml) did not suppress 3H-TdR uptake by PHA-stimulated spleen cells."
1235576,Park et al. 2000,Purification to homogeneity and characterization of a novel Pseudomonas putida chromate reductase,"Cr(VI) (chromate) is a widespread environmental contaminant. Bacterial chromate reductases can convert soluble and toxic chromate to the insoluble and less toxic Cr(III). Bioremediation can therefore be effective in removing chromate from the environment, especially if the bacterial propensity for such removal is enhanced by genetic and biochemical engineering. To clone the chromate reductase-encoding gene, we purified to homogeneity (&gt;600-fold purification) and characterized a novel soluble chromate reductase from Pseudomonas putida, using ammonium sulfate precipitation (55 to 70%), anion-exchange chromatography (DEAE Sepharose CL-6B), chromatofocusing (Polybuffer exchanger 94), and gel filtration (Superose 12 HR 10/30). The enzyme activity was dependent on NADH or NADPH; the temperature and pH optima for chromate reduction were 80 degrees C and 5, respectively; and the K(m) was 374 microM, with a V(max) of 1.72 micromol/min/mg of protein. Sulfate inhibited the enzyme activity noncompetitively. The reductase activity remained virtually unaltered after 30 min of exposure to 50 degrees C; even exposure to higher temperatures did not immediately inactivate the enzyme. X-ray absorption near-edge-structure spectra showed quantitative conversion of chromate to Cr(III) during the enzyme reaction.","Purification to homogeneity and characterization of a novel Pseudomonas putida chromate reductase Abs: Cr(VI) (chromate) is a widespread environmental contaminant. Bacterial chromate reductases can convert soluble and toxic chromate to the insoluble and less toxic Cr(III). Bioremediation can therefore be effective in removing chromate from the environment, especially if the bacterial propensity for such removal is enhanced by genetic and biochemical engineering. To clone the chromate reductase-encoding gene, we purified to homogeneity (&gt;600-fold purification) and characterized a novel soluble chromate reductase from Pseudomonas putida, using ammonium sulfate precipitation (55 to 70%), anion-exchange chromatography (DEAE Sepharose CL-6B), chromatofocusing (Polybuffer exchanger 94), and gel filtration (Superose 12 HR 10/30). The enzyme activity was dependent on NADH or NADPH; the temperature and pH optima for chromate reduction were 80 degrees C and 5, respectively; and the K(m) was 374 microM, with a V(max) of 1.72 micromol/min/mg of protein. Sulfate inhibited the enzyme activity noncompetitively. The reductase activity remained virtually unaltered after 30 min of exposure to 50 degrees C; even exposure to higher temperatures did not immediately inactivate the enzyme. X-ray absorption near-edge-structure spectra showed quantitative conversion of chromate to Cr(III) during the enzyme reaction."
1235572,Stohs et al. 2000,Oxidative mechanisms in the toxicity of chromium and cadmium ions,"Chromium and cadmium are widely used industrial chemicals. The toxicities associated with both metal ions are well known. However, less information is available concerning the mechanisms of toxicity. The results of in vitro and in vivo studies demonstrate that both cations induce an oxidative stress that results in oxidative deterioration of biological macromolecules. However, different mechanisms are involved in the production of the oxidative stress by chromium and cadmium. Chromium undergoes redox cycling, while cadmium depletes glutathione and protein-bound sulfhydryl groups, resulting in enhanced production of reactive oxygen species such as superoxide ion, hydroxyl radicals, and hydrogen peroxide. These reactive oxygen species result in increased lipid peroxidation, enhanced excretion of urinary lipid metabolites, modulation of intracellular oxidized states, DNA damage, membrane damage, altered gene expression, and apoptosis. Enhanced production of nuclear factor-kappaB and activation of protein kinase C occur. Furthermore, the p53 tumor suppressor gene is involved in the cascade of events associated with the toxicities of these cations. In summary, the results clearly indicate that although different mechanisms lead to the production of reactive oxygen species by chromium and cadmium, similar subsequent mechanisms and types of oxidative tissue damage are involved in the overall toxicities.","Oxidative mechanisms in the toxicity of chromium and cadmium ions Abs: Chromium and cadmium are widely used industrial chemicals. The toxicities associated with both metal ions are well known. However, less information is available concerning the mechanisms of toxicity. The results of in vitro and in vivo studies demonstrate that both cations induce an oxidative stress that results in oxidative deterioration of biological macromolecules. However, different mechanisms are involved in the production of the oxidative stress by chromium and cadmium. Chromium undergoes redox cycling, while cadmium depletes glutathione and protein-bound sulfhydryl groups, resulting in enhanced production of reactive oxygen species such as superoxide ion, hydroxyl radicals, and hydrogen peroxide. These reactive oxygen species result in increased lipid peroxidation, enhanced excretion of urinary lipid metabolites, modulation of intracellular oxidized states, DNA damage, membrane damage, altered gene expression, and apoptosis. Enhanced production of nuclear factor-kappaB and activation of protein kinase C occur. Furthermore, the p53 tumor suppressor gene is involved in the cascade of events associated with the toxicities of these cations. In summary, the results clearly indicate that although different mechanisms lead to the production of reactive oxygen species by chromium and cadmium, similar subsequent mechanisms and types of oxidative tissue damage are involved in the overall toxicities."
1235570,Chen et al. 2000,Participation of MAP kinase p38 and IkappaB kinase in chromium (VI)-induced NF-kappaB and AP-1 activation,"Epidemiological studies demonstrate that environmental and occupational exposure of chromium(VI) [Cr(VI)] or Cr(VI)-containing particles can cause a number of human diseases, including inflammation and cancer. The biological mechanisms responsible for the initiation and progression of diseases resulting from exposure to Cr(VI) are not fully understood. The present studies evaluated the ability of Cr(IV) to induce activation of NF-kappaB and AP-1, two important transcription factors governing the expression of many early response genes involved in inflammation and carcinogenesis. The activation of NF-kappaB and AP-1 by Cr(IV) was dose dependent. Aspirin, a well-established antioxidant, substantially inhibited Cr(VI)-induced activation of both NF-kappaB and AP-1. SB202190, a specific inhibitor for p38, attenuated AP-1 activation induced by Cr(IV), whereas PD98059, a specific inhibitor for Erk, exhibited no effect on Cr(IV)-induced AP-1 activation. Blockage of NF-kappaB signaling pathway by a transient transfection of a dominant negative expressing vector for IkappaB kinase beta resulted in inhibition of Cr(IV)-induced NF-kappaB, but not AP-1 activation. These data suggest that the activation of AP-1 or NF-kappaB by Cr(IV) is through the involvement of MAP kinase or IKK pathway, respectively.","Participation of MAP kinase p38 and IkappaB kinase in chromium (VI)-induced NF-kappaB and AP-1 activation Abs: Epidemiological studies demonstrate that environmental and occupational exposure of chromium(VI) [Cr(VI)] or Cr(VI)-containing particles can cause a number of human diseases, including inflammation and cancer. The biological mechanisms responsible for the initiation and progression of diseases resulting from exposure to Cr(VI) are not fully understood. The present studies evaluated the ability of Cr(IV) to induce activation of NF-kappaB and AP-1, two important transcription factors governing the expression of many early response genes involved in inflammation and carcinogenesis. The activation of NF-kappaB and AP-1 by Cr(IV) was dose dependent. Aspirin, a well-established antioxidant, substantially inhibited Cr(VI)-induced activation of both NF-kappaB and AP-1. SB202190, a specific inhibitor for p38, attenuated AP-1 activation induced by Cr(IV), whereas PD98059, a specific inhibitor for Erk, exhibited no effect on Cr(IV)-induced AP-1 activation. Blockage of NF-kappaB signaling pathway by a transient transfection of a dominant negative expressing vector for IkappaB kinase beta resulted in inhibition of Cr(IV)-induced NF-kappaB, but not AP-1 activation. These data suggest that the activation of AP-1 or NF-kappaB by Cr(IV) is through the involvement of MAP kinase or IKK pathway, respectively."
1235569,Katabami et al. 2000,Frequent cyclin D1 expression in chromate-induced lung cancers,"Ex-chromate workers are frequently afflicted with lung cancers, especially central-type squamous cell carcinomas (SCCs) of the lung. However, little is known about the molecular and cellular biologic characteristics of chromate-induced lung cancers. We investigated expression of cyclin D1, bcl-2, and p53 proteins in chromate-induced lung cancers by immunohistochemistry, compared with those in lung cancers from nonexposed individuals and those in individuals with pneumoconiosis. Of 19 chromate-induced lung cancers, 16 tumors were SCCs, including 11 central and 5 peripheral types. Eleven (69%) of 16 chromate SCCs showed cyclin D1 expression. In contrast, cyclin D1 expression was observed in only 3 (12%) of 26 SCCs from nonexposed individuals and 6 (16%) of 37 SCCs that developed in patients with pneumoconiosis, respectively. The frequency of cyclin D1 expression proved to be significantly higher in chromate-induced SCCs than in SCCs from nonexposed individuals and from those with pneumoconiosis (P &lt; .001). When comparisons were extended to all histologic types of lung cancer, cyclin D1 expression was observed significantly more often in chromate-induced lung cancers than in lung cancers from nonexposed subjects and those from patients with pneumoconiosis (11 [58%] of 19 v 5 [10%] of 52, P &lt; .001, and 7 [11%] of 63, P &lt; .001, respectively). Frequencies of bcl-2 and p53 expression were not significantly different among lung cancers from ex-chromate workers, nonexposed individuals and those with pneumoconiosis. The current study suggests that cyclin D1 expression may be involved in the development of chromate-induced lung cancers, although its underlying mechanism remains to be determined.","Frequent cyclin D1 expression in chromate-induced lung cancers Abs: Ex-chromate workers are frequently afflicted with lung cancers, especially central-type squamous cell carcinomas (SCCs) of the lung. However, little is known about the molecular and cellular biologic characteristics of chromate-induced lung cancers. We investigated expression of cyclin D1, bcl-2, and p53 proteins in chromate-induced lung cancers by immunohistochemistry, compared with those in lung cancers from nonexposed individuals and those in individuals with pneumoconiosis. Of 19 chromate-induced lung cancers, 16 tumors were SCCs, including 11 central and 5 peripheral types. Eleven (69%) of 16 chromate SCCs showed cyclin D1 expression. In contrast, cyclin D1 expression was observed in only 3 (12%) of 26 SCCs from nonexposed individuals and 6 (16%) of 37 SCCs that developed in patients with pneumoconiosis, respectively. The frequency of cyclin D1 expression proved to be significantly higher in chromate-induced SCCs than in SCCs from nonexposed individuals and from those with pneumoconiosis (P &lt; .001). When comparisons were extended to all histologic types of lung cancer, cyclin D1 expression was observed significantly more often in chromate-induced lung cancers than in lung cancers from nonexposed subjects and those from patients with pneumoconiosis (11 [58%] of 19 v 5 [10%] of 52, P &lt; .001, and 7 [11%] of 63, P &lt; .001, respectively). Frequencies of bcl-2 and p53 expression were not significantly different among lung cancers from ex-chromate workers, nonexposed individuals and those with pneumoconiosis. The current study suggests that cyclin D1 expression may be involved in the development of chromate-induced lung cancers, although its underlying mechanism remains to be determined."
1235566,Zhitkovich et al. 2000,Reductive metabolism of Cr(VI) by cysteine leads to the formation of binary and ternary Cr--DNA adducts in the absence of oxidative DNA damage,"Carcinogenic chromium(VI) compounds require reduction for the induction of genotoxicity. In this work, we examined a spectrum of DNA damage produced in Cr(VI)-cysteine reactions at neutral pH. Cr(VI) reduction followed single-component kinetics and led to a significant oxidation of 2',7'-dichlorofluoroscein (DCFH). The presence of residual Fe and/or Cu resulted in an increased level of oxidation of DCFH, and the removal of adventitious metals required rigorous purification of cysteine. DNA breakage and abasic sites were not detected, suggesting that DNA is much less susceptible to oxidation than DCFH. Cr(VI) reduction led to the extensive formation of Cr-DNA adducts and Cys-Cr-DNA and interstrand DNA-DNA cross-links. Cr-DNA binding resulted in unwinding of supercoiled DNA and a greater stability of the DNA duplex to denaturation. Ionically bound Cr comprised 40-60% of the total DNA-bound Cr, while the remaining Cr-DNA complexes represented stable Cr-DNA adducts that exhibited significant resistance to dissociation by EDTA. The yield of Cr-DNA adducts was strongly influenced by the nature of the buffer that was used. Phosphate buffer completely blocked Cr-DNA binding, whereas adduct formation in organic buffers was largely dependent on the extent of buffer ionization. The level of formation of Cr-DNA adducts was several times higher at pH 6 which resulted from lower levels of buffer ionization and diminished competition from hydroxyl ions. Yield of a number of Cr-DNA and Cys-DNA adducts increased linearly as a function of Cr(VI) concentration, whereas formation of interstrand DNA cross-links exhibited exponential dose dependence. Approximately 60-90 min was required to convert a Cr-DNA monoadduct into a DNA-DNA cross-link. Prolonged incubations at alkaline conditions led to a selective cleavage of cross-linked DNA. The alkali sensitivity of Cr-adducted DNA suggests that results of alkaline elution analysis of DNA damage in cells require a more cautious interpretation. Overall, a spectrum of DNA damage derived from Cr(VI)-cysteine reactions was similar to that found in exposed cells.","Reductive metabolism of Cr(VI) by cysteine leads to the formation of binary and ternary Cr--DNA adducts in the absence of oxidative DNA damage Abs: Carcinogenic chromium(VI) compounds require reduction for the induction of genotoxicity. In this work, we examined a spectrum of DNA damage produced in Cr(VI)-cysteine reactions at neutral pH. Cr(VI) reduction followed single-component kinetics and led to a significant oxidation of 2',7'-dichlorofluoroscein (DCFH). The presence of residual Fe and/or Cu resulted in an increased level of oxidation of DCFH, and the removal of adventitious metals required rigorous purification of cysteine. DNA breakage and abasic sites were not detected, suggesting that DNA is much less susceptible to oxidation than DCFH. Cr(VI) reduction led to the extensive formation of Cr-DNA adducts and Cys-Cr-DNA and interstrand DNA-DNA cross-links. Cr-DNA binding resulted in unwinding of supercoiled DNA and a greater stability of the DNA duplex to denaturation. Ionically bound Cr comprised 40-60% of the total DNA-bound Cr, while the remaining Cr-DNA complexes represented stable Cr-DNA adducts that exhibited significant resistance to dissociation by EDTA. The yield of Cr-DNA adducts was strongly influenced by the nature of the buffer that was used. Phosphate buffer completely blocked Cr-DNA binding, whereas adduct formation in organic buffers was largely dependent on the extent of buffer ionization. The level of formation of Cr-DNA adducts was several times higher at pH 6 which resulted from lower levels of buffer ionization and diminished competition from hydroxyl ions. Yield of a number of Cr-DNA and Cys-DNA adducts increased linearly as a function of Cr(VI) concentration, whereas formation of interstrand DNA cross-links exhibited exponential dose dependence. Approximately 60-90 min was required to convert a Cr-DNA monoadduct into a DNA-DNA cross-link. Prolonged incubations at alkaline conditions led to a selective cleavage of cross-linked DNA. The alkali sensitivity of Cr-adducted DNA suggests that results of alkaline elution analysis of DNA damage in cells require a more cautious interpretation. Overall, a spectrum of DNA damage derived from Cr(VI)-cysteine reactions was similar to that found in exposed cells."
1235560,Mclean and  Beveridge 2001,Chromate reduction by a pseudomonad isolated from a site contaminated with chromated copper arsenate,"A pseudomonad (CRB5) isolated from a decommissioned wood preservation site reduced toxic chromate [Cr(VI)] to an insoluble Cr(III) precipitate under aerobic and anaerobic conditions. CRB5 tolerated up to 520 mg of Cr(VI) liter(-1) and reduced chromate in the presence of copper and arsenate. Under anaerobic conditions it also reduced Co(III) and U(VI), partially internalizing each metal. Metal precipitates were also found on the surface of the outer membrane and (sometimes) on a capsule. The results showed that chromate reduction by CRB5 was mediated by a soluble enzyme that was largely contained in the cytoplasm but also found outside of the cells. The crude reductase activity in the soluble fraction showed a K(m) of 23 mg liter(-1) (437 microM) and a V(max) of 0.98 mg of Cr h(-1) mg of protein(-1) (317 nmol min(-1) mg of protein(-1)). Minor membrane-associated Cr(VI) reduction under anaerobiosis may account for anaerobic reduction of chromate under nongrowth conditions with an organic electron donor present. Chromate reduction under both aerobic and anaerobic conditions may be a detoxification strategy for the bacterium which could be exploited to bioremediate chromate-contaminated or other toxic heavy metal-contaminated environments.","Chromate reduction by a pseudomonad isolated from a site contaminated with chromated copper arsenate Abs: A pseudomonad (CRB5) isolated from a decommissioned wood preservation site reduced toxic chromate [Cr(VI)] to an insoluble Cr(III) precipitate under aerobic and anaerobic conditions. CRB5 tolerated up to 520 mg of Cr(VI) liter(-1) and reduced chromate in the presence of copper and arsenate. Under anaerobic conditions it also reduced Co(III) and U(VI), partially internalizing each metal. Metal precipitates were also found on the surface of the outer membrane and (sometimes) on a capsule. The results showed that chromate reduction by CRB5 was mediated by a soluble enzyme that was largely contained in the cytoplasm but also found outside of the cells. The crude reductase activity in the soluble fraction showed a K(m) of 23 mg liter(-1) (437 microM) and a V(max) of 0.98 mg of Cr h(-1) mg of protein(-1) (317 nmol min(-1) mg of protein(-1)). Minor membrane-associated Cr(VI) reduction under anaerobiosis may account for anaerobic reduction of chromate under nongrowth conditions with an organic electron donor present. Chromate reduction under both aerobic and anaerobic conditions may be a detoxification strategy for the bacterium which could be exploited to bioremediate chromate-contaminated or other toxic heavy metal-contaminated environments."
1235558,Ermolli et al. 2001,"Nickel, cobalt and chromium-induced cytotoxicity and intracellular accumulation in human hacat keratinocytes","Nickel, cobalt and chromium can induce allergic contact dermatitis (ACD) and may provoke irritant reactions in the skin. This study aimed at investigating cytotoxicity and cell viability along with intracellular metal accumulation in HaCaT human keratinocytes exposed to soluble forms of nickel, cobalt or chromium. The EC50 (24 h) values as detected by MTT test were 30 microM for sodium chromate (Na2CrO4), 475 microM for cobalt chloride (CoCl2) and 600 microM for nickel chloride (NiCl2). Chromium chloride (CrCl3) was not toxic up to 1 mM. No clear effects were observed after 4 h, but 24-h treatments with 1 mM CoCl2 or 10 microM Na2CrO(4) were found to almost completely abolish the ability of the cells to form colonies, whilst 1 mM NiCl2 reduced cellular survival to only 70% of control cultures. Intracellular accumulation of metals was evaluated by the use of radioisotopes at the EC50 value and at 1/10-1/5 of this concentration. Accumulation of Na2(51)CrO4 was linear with increasing dose. This was not the case for 63NiCl2 and 58CoCl2. All the metals were accumulated preferentially in the cytosols; 96% or more for 63NiCl2, approximately 90% for 58CoCl2 and 60-70% for Na2(51)CrO4. Finally, it was observed that HaCaT human keratinocytes can concentrate the metals present in the media up to 3.9 and 12.5 times for NiCl2 and CoCl2, respectively, and up to 167 for Na2CrO4. These striking metal intracellular accumulation patterns, which have not been earlier described in keratinocytes, highlight the relevance of searching for specific biomarkers of early cellular toxic effects, such as cytosolic proteins that bind the metals.","Nickel, cobalt and chromium-induced cytotoxicity and intracellular accumulation in human hacat keratinocytes Abs: Nickel, cobalt and chromium can induce allergic contact dermatitis (ACD) and may provoke irritant reactions in the skin. This study aimed at investigating cytotoxicity and cell viability along with intracellular metal accumulation in HaCaT human keratinocytes exposed to soluble forms of nickel, cobalt or chromium. The EC50 (24 h) values as detected by MTT test were 30 microM for sodium chromate (Na2CrO4), 475 microM for cobalt chloride (CoCl2) and 600 microM for nickel chloride (NiCl2). Chromium chloride (CrCl3) was not toxic up to 1 mM. No clear effects were observed after 4 h, but 24-h treatments with 1 mM CoCl2 or 10 microM Na2CrO(4) were found to almost completely abolish the ability of the cells to form colonies, whilst 1 mM NiCl2 reduced cellular survival to only 70% of control cultures. Intracellular accumulation of metals was evaluated by the use of radioisotopes at the EC50 value and at 1/10-1/5 of this concentration. Accumulation of Na2(51)CrO4 was linear with increasing dose. This was not the case for 63NiCl2 and 58CoCl2. All the metals were accumulated preferentially in the cytosols; 96% or more for 63NiCl2, approximately 90% for 58CoCl2 and 60-70% for Na2(51)CrO4. Finally, it was observed that HaCaT human keratinocytes can concentrate the metals present in the media up to 3.9 and 12.5 times for NiCl2 and CoCl2, respectively, and up to 167 for Na2CrO4. These striking metal intracellular accumulation patterns, which have not been earlier described in keratinocytes, highlight the relevance of searching for specific biomarkers of early cellular toxic effects, such as cytosolic proteins that bind the metals."
1235554,Marsh and  Mcinerney 2001,Relationship of hydrogen bioavailability to chromate reduction in aquifer sediments,"Biological Cr(VI) reduction was studied in anaerobic sediments from an aquifer in Norman, Okla. Microcosms containing sediment and mineral medium were amended with various electron donors to determine those most important for biological Cr(VI) reduction. Cr(VI) (about 340 microM) was reduced with endogenous substrates (no donor), or acetate was added. The addition of formate, hydrogen, and glucose stimulated Cr(VI) reduction compared with reduction in unamended controls. From these sediments, an anaerobic Cr(VI)-utilizing enrichment was obtained that was dependent upon hydrogen for both growth and Cr(VI) reduction. No methane was produced by the enrichment, which reduced about 750 microM Cr(VI) in less than six days. The dissolved hydrogen concentration was used as an indicator of the terminal electron accepting process occurring in the sediments. Microcosms with sediments, groundwater, and chromate metabolized hydrogen to a concentration below the detection limits of the mercury vapor gas chromatograph. In microcosms without chromate, the hydrogen concentration was about 8 nM, a concentration comparable to that under methanogenic conditions. When these microcosms were amended with 500 microM Cr(VI), the dissolved hydrogen concentration quickly fell below the detection limits. These results showed that the hydrogen concentration under chromate-reducing conditions became very low, as low as that reported under nitrate- and manganese-reducing conditions, a result consistent with the free energy changes for these reactions. The utilization of formate, lactate, hydrogen, and glucose as electron donors for Cr(VI) reduction indicates that increasing the availability of hydrogen results in a greater capacity for Cr(VI) reduction. This conclusion is supported by the existence of an enrichment dependent upon hydrogen for growth and Cr(VI) reduction.","Relationship of hydrogen bioavailability to chromate reduction in aquifer sediments Abs: Biological Cr(VI) reduction was studied in anaerobic sediments from an aquifer in Norman, Okla. Microcosms containing sediment and mineral medium were amended with various electron donors to determine those most important for biological Cr(VI) reduction. Cr(VI) (about 340 microM) was reduced with endogenous substrates (no donor), or acetate was added. The addition of formate, hydrogen, and glucose stimulated Cr(VI) reduction compared with reduction in unamended controls. From these sediments, an anaerobic Cr(VI)-utilizing enrichment was obtained that was dependent upon hydrogen for both growth and Cr(VI) reduction. No methane was produced by the enrichment, which reduced about 750 microM Cr(VI) in less than six days. The dissolved hydrogen concentration was used as an indicator of the terminal electron accepting process occurring in the sediments. Microcosms with sediments, groundwater, and chromate metabolized hydrogen to a concentration below the detection limits of the mercury vapor gas chromatograph. In microcosms without chromate, the hydrogen concentration was about 8 nM, a concentration comparable to that under methanogenic conditions. When these microcosms were amended with 500 microM Cr(VI), the dissolved hydrogen concentration quickly fell below the detection limits. These results showed that the hydrogen concentration under chromate-reducing conditions became very low, as low as that reported under nitrate- and manganese-reducing conditions, a result consistent with the free energy changes for these reactions. The utilization of formate, lactate, hydrogen, and glucose as electron donors for Cr(VI) reduction indicates that increasing the availability of hydrogen results in a greater capacity for Cr(VI) reduction. This conclusion is supported by the existence of an enrichment dependent upon hydrogen for growth and Cr(VI) reduction."
1235553,Lapuma 2001,Validation for a recirculation model,"Recent Clean Air Act regulations designed to reduce volatile organic compound (VOC) emissions have placed new restrictions on painting operations. Treating large volumes of air which contain dilute quantities of VOCs can be expensive. Recirculating some fraction of the air allows an operator to comply with environmental regulations at reduced cost. However, there is a potential impact on employee safety because indoor pollutants will inevitably increase when air is recirculated. A computer model was developed, written in Microsoft Excel 97, to predict compliance costs and indoor air concentration changes with respect to changes in the level of recirculation for a given facility. The model predicts indoor air concentrations based on product usage and mass balance equations. This article validates the recirculation model using data collected from a C-130 aircraft painting facility at Hill Air Force Base, Utah. Air sampling data and air control cost quotes from vendors were collected for the Hill AFB painting facility and compared to the model's predictions. The model's predictions for strontium chromate and isocyanate air concentrations were generally between the maximum and minimum air sampling points with a tendency to predict near the maximum sampling points. The model's capital cost predictions for a thermal VOC control device ranged from a 14 percent underestimate to a 50 percent overestimate of the average cost quotes. A sensitivity analysis of the variables is also included. The model is demonstrated to be a good evaluation tool in understanding the impact of recirculation.","Validation for a recirculation model Abs: Recent Clean Air Act regulations designed to reduce volatile organic compound (VOC) emissions have placed new restrictions on painting operations. Treating large volumes of air which contain dilute quantities of VOCs can be expensive. Recirculating some fraction of the air allows an operator to comply with environmental regulations at reduced cost. However, there is a potential impact on employee safety because indoor pollutants will inevitably increase when air is recirculated. A computer model was developed, written in Microsoft Excel 97, to predict compliance costs and indoor air concentration changes with respect to changes in the level of recirculation for a given facility. The model predicts indoor air concentrations based on product usage and mass balance equations. This article validates the recirculation model using data collected from a C-130 aircraft painting facility at Hill Air Force Base, Utah. Air sampling data and air control cost quotes from vendors were collected for the Hill AFB painting facility and compared to the model's predictions. The model's predictions for strontium chromate and isocyanate air concentrations were generally between the maximum and minimum air sampling points with a tendency to predict near the maximum sampling points. The model's capital cost predictions for a thermal VOC control device ranged from a 14 percent underestimate to a 50 percent overestimate of the average cost quotes. A sensitivity analysis of the variables is also included. The model is demonstrated to be a good evaluation tool in understanding the impact of recirculation."
1235551,Kleinsasser et al. 2001,Genotoxicity of nitroso compounds and sodium dichromate in a model combining organ cultures of human nasal epithelia and the comet assay,"Genotoxic effects of xenobiotics are a possible step in tumor initiation in the mucosa of the upper aerodigestive tract. Using the comet assay, detecting genotoxicity in human tissue has been restricted to single incubations in vitro, but in vivo most xenobiotics harm their target in a repetitive or chronic manner. Therefore, we propose a model, which provides repetitive incubations in human upper aerodigestive tract mucosa cultures. Samples of human inferior nasal turbinate mucosa (n = 25) were cultured according to a modified version of a technique originally described by Steinsvåg. On day 1 fresh samples and on days 7, 9 and 11 organ cultures were incubated with N-nitrosodiethylamine (NDEA), sodium dichromate (Na2Cr2O7) and N'-methyl-N-nitro-N-nitrosoguanidine (MNNG). Mucosa samples and organ cultures, respectively, underwent a modified comet assay on days 1, 7 and 11. Genotoxicity could be shown for NDEA, Na2Cr2O7 and MNNG on days 1, 7 and 11. Duration of tissue culture and repetitive incubations did not significantly influence the results for NDEA. Nevertheless, Na2Cr2O7 and MNNG caused higher genotoxic effects on cultures subjected to the comet assay on day 11. This model may help to assess genotoxic hazards posed by environmental pollutants that have a cumulative character in repetitive or chronic exposure in vivo.","Genotoxicity of nitroso compounds and sodium dichromate in a model combining organ cultures of human nasal epithelia and the comet assay Abs: Genotoxic effects of xenobiotics are a possible step in tumor initiation in the mucosa of the upper aerodigestive tract. Using the comet assay, detecting genotoxicity in human tissue has been restricted to single incubations in vitro, but in vivo most xenobiotics harm their target in a repetitive or chronic manner. Therefore, we propose a model, which provides repetitive incubations in human upper aerodigestive tract mucosa cultures. Samples of human inferior nasal turbinate mucosa (n = 25) were cultured according to a modified version of a technique originally described by Steinsvåg. On day 1 fresh samples and on days 7, 9 and 11 organ cultures were incubated with N-nitrosodiethylamine (NDEA), sodium dichromate (Na2Cr2O7) and N'-methyl-N-nitro-N-nitrosoguanidine (MNNG). Mucosa samples and organ cultures, respectively, underwent a modified comet assay on days 1, 7 and 11. Genotoxicity could be shown for NDEA, Na2Cr2O7 and MNNG on days 1, 7 and 11. Duration of tissue culture and repetitive incubations did not significantly influence the results for NDEA. Nevertheless, Na2Cr2O7 and MNNG caused higher genotoxic effects on cultures subjected to the comet assay on day 11. This model may help to assess genotoxic hazards posed by environmental pollutants that have a cumulative character in repetitive or chronic exposure in vivo."
1235549,Fébel et al. 2001,"Absorption of inorganic, trivalent and hexavalent chromium following oral and intrajejunal doses in rats","The intestinal absorption of trivalent and hexavalent chromium (Cr) given orally (experiment I) or infused in the intestine (experiment II) was investigated in rats. The nonabsorbable form of chromium (51Cr2O3) and water-soluble and more absorbable Na2(51)CrO4 (the hexavalent form of Cr) were compared. Total retention of chromium given orally ranged around 15 percent of the dose, regardless of the chromium compounds applied. The absorption rate of chromic oxide, which is considered a nonabsorbable compound, was 14.4 as a percentage of chromium intake. This result indicates that some loss of chromium has to be taken into account in metabolic trials made by the indicator method. In isolated rat intestine, from the injected Cr 2.5% of chromic oxide and 43.2% of sodium chromate were absorbed during an hour (experiment II). The absorbed chromium was transferred to the liver where the liver tissue retained 10.9% of chromic oxide and 51.1% of sodium chromate. Radioactivity of v. cava caudalis following intestinal injection of Na2CrO4 was thirtyfold greater than after Cr2O3 dosing. This phenomenon can be explained by the lower blood clearance of chromate. Different absorption rate of chromate depending on the route of administration could be due to the fact that the hexavalent form given orally was reduced to Cr3+ in the acidic environment of the stomach. When Na2CrO4 was infused directly in the intestine of rats, such reduction could not occur. This means that the acidic gastric juice might play a role in inhibiting the intestinal absorption of Na2CrO4 when this compound is given orally.","Absorption of inorganic, trivalent and hexavalent chromium following oral and intrajejunal doses in rats Abs: The intestinal absorption of trivalent and hexavalent chromium (Cr) given orally (experiment I) or infused in the intestine (experiment II) was investigated in rats. The nonabsorbable form of chromium (51Cr2O3) and water-soluble and more absorbable Na2(51)CrO4 (the hexavalent form of Cr) were compared. Total retention of chromium given orally ranged around 15 percent of the dose, regardless of the chromium compounds applied. The absorption rate of chromic oxide, which is considered a nonabsorbable compound, was 14.4 as a percentage of chromium intake. This result indicates that some loss of chromium has to be taken into account in metabolic trials made by the indicator method. In isolated rat intestine, from the injected Cr 2.5% of chromic oxide and 43.2% of sodium chromate were absorbed during an hour (experiment II). The absorbed chromium was transferred to the liver where the liver tissue retained 10.9% of chromic oxide and 51.1% of sodium chromate. Radioactivity of v. cava caudalis following intestinal injection of Na2CrO4 was thirtyfold greater than after Cr2O3 dosing. This phenomenon can be explained by the lower blood clearance of chromate. Different absorption rate of chromate depending on the route of administration could be due to the fact that the hexavalent form given orally was reduced to Cr3+ in the acidic environment of the stomach. When Na2CrO4 was infused directly in the intestine of rats, such reduction could not occur. This means that the acidic gastric juice might play a role in inhibiting the intestinal absorption of Na2CrO4 when this compound is given orally."
1235545,Lee et al. 2000,DNA strand breaks (comet assay) and embryo development effects in grass shrimp (Palaemonetes pugio) embryos after exposure to genotoxicants,"Grass shrimp embryos develop in egg sacs (stages 1-10) attached to the female for 14-20 days after which they 'hatch' from the egg sacs into a swimming zoea stage (stage 11). Until they emerge from the egg sacs, embryos depend on lipids and lipovitellin stored within the egg. The percent of embryos which hatch after exposure to toxicants relative to controls was the basis of an embryo development assay. Exposure of embryos to chromium(III) chloride, sodium chromate, mercuric chloride, and 2-methyl-1,2-naphthoquinone (MNQ) resulted in a reduced hatching rate. In addition to effects on embryo development, DNA strand damage tests were carried out on contaminant-exposed embryos, using the single-cell electrophoresis method often referred to as comet assay. Development of stage 4 embryos was more affected by MNQ exposure than stage 7 embryos. The hatching rates of stages 4 and 7 embryos exposed to MNQ (172 micrograms/l) were 0 and 90%, respectively. DNA strand damage, measured as DNA tail moments, were 3.4 and 4.4, respectively. Thus, exposure of an early embryo stage to MNQ prevented full embryo development while development of later embryo stages was not affected. It may be that the DNA repair systems are more efficient in later embryo stages than in early stages and thus DNA damaged in the early stages affects development.","DNA strand breaks (comet assay) and embryo development effects in grass shrimp (Palaemonetes pugio) embryos after exposure to genotoxicants Abs: Grass shrimp embryos develop in egg sacs (stages 1-10) attached to the female for 14-20 days after which they 'hatch' from the egg sacs into a swimming zoea stage (stage 11). Until they emerge from the egg sacs, embryos depend on lipids and lipovitellin stored within the egg. The percent of embryos which hatch after exposure to toxicants relative to controls was the basis of an embryo development assay. Exposure of embryos to chromium(III) chloride, sodium chromate, mercuric chloride, and 2-methyl-1,2-naphthoquinone (MNQ) resulted in a reduced hatching rate. In addition to effects on embryo development, DNA strand damage tests were carried out on contaminant-exposed embryos, using the single-cell electrophoresis method often referred to as comet assay. Development of stage 4 embryos was more affected by MNQ exposure than stage 7 embryos. The hatching rates of stages 4 and 7 embryos exposed to MNQ (172 micrograms/l) were 0 and 90%, respectively. DNA strand damage, measured as DNA tail moments, were 3.4 and 4.4, respectively. Thus, exposure of an early embryo stage to MNQ prevented full embryo development while development of later embryo stages was not affected. It may be that the DNA repair systems are more efficient in later embryo stages than in early stages and thus DNA damaged in the early stages affects development."
1235544,Appenroth et al. 2001,"LLU-alpha, an endogenous metabolite of gamma-tocopherol, is more effective against metal nephrotoxicity in rats than gamma-tocopherol","Antioxidants of the vitamin E family have protective effects against metal toxicity. We examined the protective effect of racemic LLU-alpha [2,7,8-trimethyl-2-(carboxyethyl)-6-hydroxychroman] a metabolite of gamma-tocopherol, in comparison to the effect of alpha- and gamma-tocopherol in rats treated with sodium dichromate (Cr) or thallium sulfate (Tl). We measured metal nephrotoxicity based on urinary protein excretion and discussed it with respect to the metal concentration in renal tissue. The ranking of antioxidant activity (iron stimulated lipid peroxidation, luminol and lucigenin amplified chemiluminescence) was determined in the following order: alpha-tocopherol&lt;gamma-tocopherol&lt;LLU-alpha. Pretreatment with LLU-alpha produced lower chromate nephrotoxicity than alpha- or gamma-tocopherol, but did not influence Cr concentration in renal tissue. The protective effect of LLU-alpha against Cr toxicity seemed to be caused by its stronger antioxidant activity in comparison to alpha- and gamma-tocopherol. Pretreatment with LLU-alpha resulted in lower thallium-induced proteinuria, a lower concentration of Tl in the renal medulla, and higher urinary Tl excretion. Unlike LLU-alpha, which has been shown to inhibit K(+) channels in the apical membrane of the thick ascending limb of Henle's loop, we found that gamma-tocopherol did not. This finding reaffirmed the similarity between K(+) and Tl(+) and also explained the significantly decreased Tl concentration in the renal medulla in rats treated with LLU-alpha. We speculate that the protective effect of LLU-alpha against Tl nephrotoxicity is caused both by its antioxidant effect and, at least in part, by its ability to decrease Tl concentration as a consequence of inhibited Tl(+) uptake through K(+) channels. This finding confirmed the similarity between K(+) and Tl(+) and also explained the significantly decreased Tl concentration in the renal medulla in rats treated with LLU-alpha.","LLU-alpha, an endogenous metabolite of gamma-tocopherol, is more effective against metal nephrotoxicity in rats than gamma-tocopherol Abs: Antioxidants of the vitamin E family have protective effects against metal toxicity. We examined the protective effect of racemic LLU-alpha [2,7,8-trimethyl-2-(carboxyethyl)-6-hydroxychroman] a metabolite of gamma-tocopherol, in comparison to the effect of alpha- and gamma-tocopherol in rats treated with sodium dichromate (Cr) or thallium sulfate (Tl). We measured metal nephrotoxicity based on urinary protein excretion and discussed it with respect to the metal concentration in renal tissue. The ranking of antioxidant activity (iron stimulated lipid peroxidation, luminol and lucigenin amplified chemiluminescence) was determined in the following order: alpha-tocopherol&lt;gamma-tocopherol&lt;LLU-alpha. Pretreatment with LLU-alpha produced lower chromate nephrotoxicity than alpha- or gamma-tocopherol, but did not influence Cr concentration in renal tissue. The protective effect of LLU-alpha against Cr toxicity seemed to be caused by its stronger antioxidant activity in comparison to alpha- and gamma-tocopherol. Pretreatment with LLU-alpha resulted in lower thallium-induced proteinuria, a lower concentration of Tl in the renal medulla, and higher urinary Tl excretion. Unlike LLU-alpha, which has been shown to inhibit K(+) channels in the apical membrane of the thick ascending limb of Henle's loop, we found that gamma-tocopherol did not. This finding reaffirmed the similarity between K(+) and Tl(+) and also explained the significantly decreased Tl concentration in the renal medulla in rats treated with LLU-alpha. We speculate that the protective effect of LLU-alpha against Tl nephrotoxicity is caused both by its antioxidant effect and, at least in part, by its ability to decrease Tl concentration as a consequence of inhibited Tl(+) uptake through K(+) channels. This finding confirmed the similarity between K(+) and Tl(+) and also explained the significantly decreased Tl concentration in the renal medulla in rats treated with LLU-alpha."
1235541,Yang et al. 2001,Fast analysis of water samples for detection of anions by capillary zone electrophoresis,"A capillary zone electrophoresis (CZE) method with relatively low separation voltage and short capillary length, using indirect UV detection was developed for the fast and quantitative determination of Cl-, NO2-, SO4(2-), NO3-, F- and HCO3- in potable water samples. Baseline separation of inorganic and organic anions was achieved within 1 min. The optimal carrier electrolyte consisted of 6.0 mM sodium chromate, 2.5 mM CTAB and 3.5% acetonitrile at pH 9.0. The effects of pH and the concentrations of electrolyte and flow modifiers on the resolution were investigated. Two injection methods, gravity and electrokinetic, were compared. The application of electrokinetic injection, using pyroglutamic acid as an internal standard was found to provide a method that is fast, sensitive and quantitative, with an R.S.D. for migration times from 0.1% to 0.3% and for peak areas from 1.8% to 4.1%. The limits of detection were 0.08 mg/L Cl-, 0.3 mg/L NO2-, 0.1 mg/L SO4(2-), 0.1 mg/L NO3-, 0.07 mg/L F-, and 0.3 mg/L HCO3-. This method has been successfully applied to determine Cl-, NO2-, SO4(2-), NO3-, F-, HCO3- in municipal water, surface water and bottled water samples.","Fast analysis of water samples for detection of anions by capillary zone electrophoresis Abs: A capillary zone electrophoresis (CZE) method with relatively low separation voltage and short capillary length, using indirect UV detection was developed for the fast and quantitative determination of Cl-, NO2-, SO4(2-), NO3-, F- and HCO3- in potable water samples. Baseline separation of inorganic and organic anions was achieved within 1 min. The optimal carrier electrolyte consisted of 6.0 mM sodium chromate, 2.5 mM CTAB and 3.5% acetonitrile at pH 9.0. The effects of pH and the concentrations of electrolyte and flow modifiers on the resolution were investigated. Two injection methods, gravity and electrokinetic, were compared. The application of electrokinetic injection, using pyroglutamic acid as an internal standard was found to provide a method that is fast, sensitive and quantitative, with an R.S.D. for migration times from 0.1% to 0.3% and for peak areas from 1.8% to 4.1%. The limits of detection were 0.08 mg/L Cl-, 0.3 mg/L NO2-, 0.1 mg/L SO4(2-), 0.1 mg/L NO3-, 0.07 mg/L F-, and 0.3 mg/L HCO3-. This method has been successfully applied to determine Cl-, NO2-, SO4(2-), NO3-, F-, HCO3- in municipal water, surface water and bottled water samples."
1235538,Unlü and  Haskök 2001,Treatability of chromite ore processing waste by leaching,"Developing treatment and disposal strategies and health-based clean-up standards for chromium containing wastes continues to be an important environmental regulatory issue because of the opposing solubility and toxicity characteristics of chromium species under diverse environmental conditions. In this study, leaching characteristics of total Cr and Cr(VI) were investigated using laboratory column studies. The data obtained from the experimental studies were analysed to assess the treatability of chromite ore processing waste (COPW) by leaching and to identify the leaching strategies that enhance mass removal rates of chromium species. COPW used for laboratory soil column studies was obtained from an industrial plant producing sodium chromate in Mersin, Turkey. Laboratory investigations involved chemical characterisation of waste material and column studies. For waste characterisation, U.S. EPA toxicity characterisation leaching procedure (TCLP) was performed on COPW to determine the concentrations of metal species in the TCLP extract. For column studies, various laboratory columns containing plain COPW material, 1:1 COPW/reducing agent (elemental iron or manure) mixture and different type soils (sand, loam and clay) overlain by COPW were subjected to leaching tests using acidic, neutral and alkaline influent water to determine Cr mass leaching efficiencies. Based on the TCLP analyses, COPW is classified as hazardous waste. As a result of comparing the leaching efficiency data from twelve leaching columns, the maximum removal of total Cr was achieved by leaching COPW/manure mixture using acidic (pH 4.78) influent water. The highest Cr(VI) leaching efficiency was achieved in the columns of plain COPW and COPW/manure mixture using highly alkaline (pH 12.0) influent water. The least effective leaching efficiency for both total Cr and Cr (VI) was obtained by leaching plain COPW with neutral (pH 7.0) influent water. Land-disposal of the treated COPW material by mixing with clayey soils seems to be a viable alternative.","Treatability of chromite ore processing waste by leaching Abs: Developing treatment and disposal strategies and health-based clean-up standards for chromium containing wastes continues to be an important environmental regulatory issue because of the opposing solubility and toxicity characteristics of chromium species under diverse environmental conditions. In this study, leaching characteristics of total Cr and Cr(VI) were investigated using laboratory column studies. The data obtained from the experimental studies were analysed to assess the treatability of chromite ore processing waste (COPW) by leaching and to identify the leaching strategies that enhance mass removal rates of chromium species. COPW used for laboratory soil column studies was obtained from an industrial plant producing sodium chromate in Mersin, Turkey. Laboratory investigations involved chemical characterisation of waste material and column studies. For waste characterisation, U.S. EPA toxicity characterisation leaching procedure (TCLP) was performed on COPW to determine the concentrations of metal species in the TCLP extract. For column studies, various laboratory columns containing plain COPW material, 1:1 COPW/reducing agent (elemental iron or manure) mixture and different type soils (sand, loam and clay) overlain by COPW were subjected to leaching tests using acidic, neutral and alkaline influent water to determine Cr mass leaching efficiencies. Based on the TCLP analyses, COPW is classified as hazardous waste. As a result of comparing the leaching efficiency data from twelve leaching columns, the maximum removal of total Cr was achieved by leaching COPW/manure mixture using acidic (pH 4.78) influent water. The highest Cr(VI) leaching efficiency was achieved in the columns of plain COPW and COPW/manure mixture using highly alkaline (pH 12.0) influent water. The least effective leaching efficiency for both total Cr and Cr (VI) was obtained by leaching plain COPW with neutral (pH 7.0) influent water. Land-disposal of the treated COPW material by mixing with clayey soils seems to be a viable alternative."
1235537,Porrata et al. 2001,Immunomodulation of early engrafted natural killer cells with interleukin-2 and interferon-alpha in autologous stem cell transplantation,"High relapse rates during the first year after autologous stem cell transplantation (ASCT) for multiple myeloma or non-Hodgkin lymphoma are due to the failure of high-dose chemotherapy to eradicate minimal residual disease. Post-ASCT immunorecovery studies have shown that quantities of natural killer (NK) cells return to normal within 1 month post-ASCT in contrast to the recovery of T and B cell populations (up to 1 year). Preclinical studies have demonstrated that NK cells have potent antitumor activity. IL-2 and IFN-alpha enhance NK-cell activity. We investigated the efficacy of IL-2 and IFN-alpha to up-regulate NK-cell cytotoxicity at 14 days post ASCT. Twenty patients undergoing ASCT had PBMCs collected pretransplantation and at 14 days post transplantation. PBMCs (effector cells) from each blood sample were incubated in vitro with IFN-alpha and IL-2 at 10000 IU/ml. NK cell activity was determined by sodium chromate (51)Cr release assay for lysis of K562 target cells. IL-2 and IFN-alpha each increased lysis of K562 cells compared with placebo (effector-to-target ratio, 50:1, P &lt; 0.001). Increased NK cell activity occurred in samples from all patients. IL-2 and IFN-alpha up-regulated NK cell activity at 14 days post ASCT. They may be useful as immunomodulators as early as 14 days post ASCT to eradicate or control minimal residual disease.","Immunomodulation of early engrafted natural killer cells with interleukin-2 and interferon-alpha in autologous stem cell transplantation Abs: High relapse rates during the first year after autologous stem cell transplantation (ASCT) for multiple myeloma or non-Hodgkin lymphoma are due to the failure of high-dose chemotherapy to eradicate minimal residual disease. Post-ASCT immunorecovery studies have shown that quantities of natural killer (NK) cells return to normal within 1 month post-ASCT in contrast to the recovery of T and B cell populations (up to 1 year). Preclinical studies have demonstrated that NK cells have potent antitumor activity. IL-2 and IFN-alpha enhance NK-cell activity. We investigated the efficacy of IL-2 and IFN-alpha to up-regulate NK-cell cytotoxicity at 14 days post ASCT. Twenty patients undergoing ASCT had PBMCs collected pretransplantation and at 14 days post transplantation. PBMCs (effector cells) from each blood sample were incubated in vitro with IFN-alpha and IL-2 at 10000 IU/ml. NK cell activity was determined by sodium chromate (51)Cr release assay for lysis of K562 target cells. IL-2 and IFN-alpha each increased lysis of K562 cells compared with placebo (effector-to-target ratio, 50:1, P &lt; 0.001). Increased NK cell activity occurred in samples from all patients. IL-2 and IFN-alpha up-regulated NK cell activity at 14 days post ASCT. They may be useful as immunomodulators as early as 14 days post ASCT to eradicate or control minimal residual disease."
1235531,Cathum et al. 2002,"Determination of Cr3+, CrO42-, and Cr2O72- in environmental matrixes by high-performance liquid chromatography with diode-array detection (HPLC-DAD)","A high-performance liquid chromatographic method with diode array detection (HPLC-DAD), based on chelation with ammonium pyrrolidinedithiocarbamate (APDC), has been developed for the determination of chromium species. Determination of Cr3+, CrO42-, and Cr2O72- was performed for standards and synthetic environmental matrixes. This method is robust, rugged, and can be used for rapid routine determination of chromium species with high precision and reliability. Sample pretreatment is simple. The method is capable of discriminating not only between Cr(III) and Cr(VI) but also between the chemical forms of Cr(VI) - CrO42- and Cr2O72-. By analysis of numerous samples the method has been shown to be selective, sensitive, and free from matrix interference, which is crucial for the determination of chromium species in difficult-to-analyze environmental matrixes. This method has been validated by means of an interlaboratory study. Although different speciation techniques were used during this study, there was good agreement between results from the two laboratories. The method detection limits were 7 and 4 mg L(-1) for Cr3+ and Cr2O72-, respectively. Recoveries of the analytes from spiked samples were 98% and 100% for Cr3+ and Cr2O72-, respectively. Both were based on a 10-mL sample volume spiked with 0.4 mg L(-1) chromium.","Determination of Cr3+, CrO42-, and Cr2O72- in environmental matrixes by high-performance liquid chromatography with diode-array detection (HPLC-DAD) Abs: A high-performance liquid chromatographic method with diode array detection (HPLC-DAD), based on chelation with ammonium pyrrolidinedithiocarbamate (APDC), has been developed for the determination of chromium species. Determination of Cr3+, CrO42-, and Cr2O72- was performed for standards and synthetic environmental matrixes. This method is robust, rugged, and can be used for rapid routine determination of chromium species with high precision and reliability. Sample pretreatment is simple. The method is capable of discriminating not only between Cr(III) and Cr(VI) but also between the chemical forms of Cr(VI) - CrO42- and Cr2O72-. By analysis of numerous samples the method has been shown to be selective, sensitive, and free from matrix interference, which is crucial for the determination of chromium species in difficult-to-analyze environmental matrixes. This method has been validated by means of an interlaboratory study. Although different speciation techniques were used during this study, there was good agreement between results from the two laboratories. The method detection limits were 7 and 4 mg L(-1) for Cr3+ and Cr2O72-, respectively. Recoveries of the analytes from spiked samples were 98% and 100% for Cr3+ and Cr2O72-, respectively. Both were based on a 10-mL sample volume spiked with 0.4 mg L(-1) chromium."
1235512,Costa 2003,Potential hazards of hexavalent chromate in our drinking water,A consideration of the consequences of human exposure to hexavalent Cr in the drinking water has been compiled. Since there is an absence of adequate human data on this subject the problem has been analyzed not only from human and animal studies but also from a mechanistic point of view. This treatise has been inspired by recent reviews and speculations that suggest that we may safely drink hexavalent Cr in great excess of the current EPA and states drinking water standards of 50-100 ppb.,Potential hazards of hexavalent chromate in our drinking water Abs: A consideration of the consequences of human exposure to hexavalent Cr in the drinking water has been compiled. Since there is an absence of adequate human data on this subject the problem has been analyzed not only from human and animal studies but also from a mechanistic point of view. This treatise has been inspired by recent reviews and speculations that suggest that we may safely drink hexavalent Cr in great excess of the current EPA and states drinking water standards of 50-100 ppb.
1235510,Tzou et al. 2003,Sorption of phosphate and Cr(VI) by Fe(III) and Cr(III) hydroxides,"Understanding the chemical behavior and interactions of Cr(VI) ( e.g., HCrO(4)(-)) and other anions, such as orthophosphate (P) with insoluble metal hydroxides ( i.e., Cr[III] and Fe[III]) in disposal landfills or in chromite ore processing residue (CORP)-enriched soil is very important in predicting the movement and the fate of Cr(VI). This study evaluates the sorption behavior of P and Cr(VI) by Fe(III) ( i.e., ferrihydrite), Cr(III) ( i.e., Cr[OH](3)), and coprecipitated Fe(III)/Cr(III) hydroxides. These metal hydroxide sorbents were synthesized, and sorption of P and Cr(VI) were conducted at different pH using a batch technology. Our results show that P and Cr(VI) sorption by metal hydroxides decreased with increasing suspension pH. Greater decrease in P sorption was observed when Cr(III) was present in the structures of hydroxides. Following the sorption of low concentration of P ( i.e., 0.5 mM), the sorption of subsequently added Cr(VI) by hydroxides was less influenced. However, Cr(VI) sorption was greatly inhibited when high concentration of P ( i.e., 10 mM) prereacted with hydroxides, particularly in Fe(III) hydroxide system. Results also indicated that high concentration of Cr(VI) (10 mM) could dissolve Cr(III) hydroxide at pH 3 and reprecipitate as an amorphous form of Cr(VI) and Cr(III) compound at pH about 6.5. Although coprecipitation of Cr(VI) with Cr(III) can inhibit Cr(VI) movement through soil profiles, the inhibition seems to be low due to the gradual release of Cr(VI) with increasing pH.","Sorption of phosphate and Cr(VI) by Fe(III) and Cr(III) hydroxides Abs: Understanding the chemical behavior and interactions of Cr(VI) ( e.g., HCrO(4)(-)) and other anions, such as orthophosphate (P) with insoluble metal hydroxides ( i.e., Cr[III] and Fe[III]) in disposal landfills or in chromite ore processing residue (CORP)-enriched soil is very important in predicting the movement and the fate of Cr(VI). This study evaluates the sorption behavior of P and Cr(VI) by Fe(III) ( i.e., ferrihydrite), Cr(III) ( i.e., Cr[OH](3)), and coprecipitated Fe(III)/Cr(III) hydroxides. These metal hydroxide sorbents were synthesized, and sorption of P and Cr(VI) were conducted at different pH using a batch technology. Our results show that P and Cr(VI) sorption by metal hydroxides decreased with increasing suspension pH. Greater decrease in P sorption was observed when Cr(III) was present in the structures of hydroxides. Following the sorption of low concentration of P ( i.e., 0.5 mM), the sorption of subsequently added Cr(VI) by hydroxides was less influenced. However, Cr(VI) sorption was greatly inhibited when high concentration of P ( i.e., 10 mM) prereacted with hydroxides, particularly in Fe(III) hydroxide system. Results also indicated that high concentration of Cr(VI) (10 mM) could dissolve Cr(III) hydroxide at pH 3 and reprecipitate as an amorphous form of Cr(VI) and Cr(III) compound at pH about 6.5. Although coprecipitation of Cr(VI) with Cr(III) can inhibit Cr(VI) movement through soil profiles, the inhibition seems to be low due to the gradual release of Cr(VI) with increasing pH."
1235505,Luippold et al. 2003,Lung cancer mortality among chromate production workers,"<strong>AIMS: </strong>To assess mortality in 1997 among 493 former workers of a US chromate production plant employed for at least one year between 1940 and 1972.<br /><br /><strong>METHODS: </strong>Cohort members were followed for mortality to 31 December 1997. Standardised mortality ratios (SMRs) were calculated for selected cause specific categories of death including lung cancer. Lung cancer mortality was investigated further by calculation of SMRs stratified by year of hire, duration of employment, time since hire, and categories of cumulative exposure to Cr(VI).<br /><br /><strong>RESULTS: </strong>Including 51 deaths due to lung cancer, 303 deaths occurred. SMRs were significantly increased for all causes combined (SMR = 129), all cancers combined (SMR = 155), and lung cancer (SMR = 241). A trend test showed a strong relation between lung cancer mortality and cumulative hexavalent exposure. Lung cancer mortality was increased for the highest cumulative exposure categories (&gt; or =1.05 to &lt;2.70 mg/m(3)-years, SMR = 365; &gt; or =2.70 to 23 mg/m(3)-years, SMR = 463), but not for the first three exposure groups. Significantly increased SMRs were also found for year of hire before 1960, 20 or more years of exposed employment, and latency of 20 or more years.<br /><br /><strong>CONCLUSIONS: </strong>The finding of an increased risk of lung cancer mortality associated with Cr(VI) exposure is consistent with previous reports. Stratified analysis of lung cancer mortality by cumulative exposure suggests a possible threshold effect, as risk is significantly increased only at exposure levels over 1.05 mg/m(3)-years. Though a threshold is consistent with published toxicological evidence, this finding must be interpreted cautiously because the data are also consistent with a linear dose response.","Lung cancer mortality among chromate production workers Abs: <strong>AIMS: </strong>To assess mortality in 1997 among 493 former workers of a US chromate production plant employed for at least one year between 1940 and 1972.<br /><br /><strong>METHODS: </strong>Cohort members were followed for mortality to 31 December 1997. Standardised mortality ratios (SMRs) were calculated for selected cause specific categories of death including lung cancer. Lung cancer mortality was investigated further by calculation of SMRs stratified by year of hire, duration of employment, time since hire, and categories of cumulative exposure to Cr(VI).<br /><br /><strong>RESULTS: </strong>Including 51 deaths due to lung cancer, 303 deaths occurred. SMRs were significantly increased for all causes combined (SMR = 129), all cancers combined (SMR = 155), and lung cancer (SMR = 241). A trend test showed a strong relation between lung cancer mortality and cumulative hexavalent exposure. Lung cancer mortality was increased for the highest cumulative exposure categories (&gt; or =1.05 to &lt;2.70 mg/m(3)-years, SMR = 365; &gt; or =2.70 to 23 mg/m(3)-years, SMR = 463), but not for the first three exposure groups. Significantly increased SMRs were also found for year of hire before 1960, 20 or more years of exposed employment, and latency of 20 or more years.<br /><br /><strong>CONCLUSIONS: </strong>The finding of an increased risk of lung cancer mortality associated with Cr(VI) exposure is consistent with previous reports. Stratified analysis of lung cancer mortality by cumulative exposure suggests a possible threshold effect, as risk is significantly increased only at exposure levels over 1.05 mg/m(3)-years. Though a threshold is consistent with published toxicological evidence, this finding must be interpreted cautiously because the data are also consistent with a linear dose response."
1235502,Krepkiy et al. 2003,Properties of the reaction of chromate with metallothionein,"The reactivity of chromate or Cr(VI) with rabbit liver metallothionein (MT) was explored in this study. Zn(7)-MT reacts very slowly with Cr(VI) in a process characterized by a second-order rate constant of 3.9 x 10(-)(4) M(-)(1) s(-)(1). During the reaction, Zn(2+) was released from the protein. In contrast, apo-MT reduces chromate quicker and in this reaction is much more effective as a reducing agent, when compared to Cys or GSH. The kinetics are consistent with a reaction pathway involving an initial binding step followed by the reduction of Cr(VI). In the process, MT sulfhydryl groups were oxidized at the same rate that Cr(VI) disappeared. A Cr(V) intermediate was detected by EPR spectroscopy immediately upon mixing apo-MT with Cr(VI). The Cr(V) signal decayed during the reaction but was quite stable and could be observed for hours once the supply of thiols was depleted. The g values for the Cr(V) species were 2.014 and 1.987. The kinetics of the reaction of Cr(VI) and the concentration of the intermediate Cr(V) signal were independent of the oxygen concentration and were unaffected by the presence of superoxide dismutase, catalase, or DMSO. In the presence of oxygen, oxy radicals were generated according to ESR spin-trapping experiments with 5,5'-dimethyl-1-pyrroline-N-oxide. Superoxide dismutase decreased and catalase or DMSO largely inhibited the formation of the spin-trapped adduct. Cr(III), the presumed final species of the Cr(VI) reduction, formed a stable complex with apo-MT in the absence of oxygen with an average stoichiometry of two Cr ions bound per protein molecule. Upon addition of O(2), the complex slowly dissociated.","Properties of the reaction of chromate with metallothionein Abs: The reactivity of chromate or Cr(VI) with rabbit liver metallothionein (MT) was explored in this study. Zn(7)-MT reacts very slowly with Cr(VI) in a process characterized by a second-order rate constant of 3.9 x 10(-)(4) M(-)(1) s(-)(1). During the reaction, Zn(2+) was released from the protein. In contrast, apo-MT reduces chromate quicker and in this reaction is much more effective as a reducing agent, when compared to Cys or GSH. The kinetics are consistent with a reaction pathway involving an initial binding step followed by the reduction of Cr(VI). In the process, MT sulfhydryl groups were oxidized at the same rate that Cr(VI) disappeared. A Cr(V) intermediate was detected by EPR spectroscopy immediately upon mixing apo-MT with Cr(VI). The Cr(V) signal decayed during the reaction but was quite stable and could be observed for hours once the supply of thiols was depleted. The g values for the Cr(V) species were 2.014 and 1.987. The kinetics of the reaction of Cr(VI) and the concentration of the intermediate Cr(V) signal were independent of the oxygen concentration and were unaffected by the presence of superoxide dismutase, catalase, or DMSO. In the presence of oxygen, oxy radicals were generated according to ESR spin-trapping experiments with 5,5'-dimethyl-1-pyrroline-N-oxide. Superoxide dismutase decreased and catalase or DMSO largely inhibited the formation of the spin-trapped adduct. Cr(III), the presumed final species of the Cr(VI) reduction, formed a stable complex with apo-MT in the absence of oxygen with an average stoichiometry of two Cr ions bound per protein molecule. Upon addition of O(2), the complex slowly dissociated."
1235497,Ayres et al. 2003,A comparative study of the JAM test and 51Cr-release assay to assess the cytotoxicity of dendritic cells on hematopoietic tumor cells,"Dendritic cells (DCs) are potent antigen presenting cells and possess a direct anti-tumor cytotoxic ability. Nevertheless, the mechanism of anti-tumor cytotoxicity by DCs and the methods for its evaluation are not fully elucidated. In order to clarify this mechanism of cytotoxicity, we examined the ability of DCs 1) to suppress [3H] thymidine (3H-TdR) uptake by tumor cells; 2) to induce cytolysis on 51Cr-labeled tumor cells; 3) and to induce DNA fragmentation on 3H-TdR labeled tumor cells (JAM test). Cytolysis and DNA fragmentation are markers of necrotic and apoptotic mechanisms of cytotoxicity in vitro, respectively. DCs inhibited approximately 38.6% to 54.8% of the growth of B4D6, NB4, U937, and Daudi cells as evaluated by the uptake of 3H-TdR. However no cytolysis was verified by 51Cr-release assay. On the other hand, cytotoxicity rates found using the JAM test ranged from 3 to 81% depending on the cell line and the effector to target cell ratio. The discrepancy of cytotoxicity between 51Cr-release assay and the JAM test may be due to the phagocytosis of apoptotic tumor cells or the absorption of released 51Cr by DCs surrounding the target cells. In conclusion, the JAM test was more sensitive than the 4-h and the 10-h 51Cr-release assay to investigate cytotoxicity mediated by DCs toward hematopoietic tumor cell lines in vitro.","A comparative study of the JAM test and 51Cr-release assay to assess the cytotoxicity of dendritic cells on hematopoietic tumor cells Abs: Dendritic cells (DCs) are potent antigen presenting cells and possess a direct anti-tumor cytotoxic ability. Nevertheless, the mechanism of anti-tumor cytotoxicity by DCs and the methods for its evaluation are not fully elucidated. In order to clarify this mechanism of cytotoxicity, we examined the ability of DCs 1) to suppress [3H] thymidine (3H-TdR) uptake by tumor cells; 2) to induce cytolysis on 51Cr-labeled tumor cells; 3) and to induce DNA fragmentation on 3H-TdR labeled tumor cells (JAM test). Cytolysis and DNA fragmentation are markers of necrotic and apoptotic mechanisms of cytotoxicity in vitro, respectively. DCs inhibited approximately 38.6% to 54.8% of the growth of B4D6, NB4, U937, and Daudi cells as evaluated by the uptake of 3H-TdR. However no cytolysis was verified by 51Cr-release assay. On the other hand, cytotoxicity rates found using the JAM test ranged from 3 to 81% depending on the cell line and the effector to target cell ratio. The discrepancy of cytotoxicity between 51Cr-release assay and the JAM test may be due to the phagocytosis of apoptotic tumor cells or the absorption of released 51Cr by DCs surrounding the target cells. In conclusion, the JAM test was more sensitive than the 4-h and the 10-h 51Cr-release assay to investigate cytotoxicity mediated by DCs toward hematopoietic tumor cell lines in vitro."
1235488,Ackerley et al. 2004,Chromate-reducing properties of soluble flavoproteins from Pseudomonas putida and Escherichia coli,"Cr(VI) (chromate) is a toxic, soluble environmental contaminant. Bacteria can reduce chromate to the insoluble and less toxic Cr(III), and thus chromate bioremediation is of interest. Genetic and protein engineering of suitable enzymes can improve bacterial bioremediation. Many bacterial enzymes catalyze one-electron reduction of chromate, generating Cr(V), which redox cycles, generating excessive reactive oxygen species (ROS). Such enzymes are not appropriate for bioremediation, as they harm the bacteria and their primary end product is not Cr(III). In this work, the chromate reductase activities of two electrophoretically pure soluble bacterial flavoproteins--ChrR (from Pseudomonas putida) and YieF (from Escherichia coli)-were examined. Both are dimers and reduce chromate efficiently to Cr(III) (kcat/Km = approximately 2 x 10(4) M(-1) x s(-1)). The ChrR dimer generated a flavin semiquinone during chromate reduction and transferred &gt;25% of the NADH electrons to ROS. However, the semiquinone was formed transiently and ROS diminished with time. Thus, ChrR probably generates Cr(V), but only transiently. Studies with mutants showed that ChrR protects against chromate toxicity; this is possibly because it preempts chromate reduction by the cellular one-electron reducers, thereby minimizing ROS generation. ChrR is thus a suitable enzyme for further studies. During chromate reduction by YieF, no flavin semiquinone was generated and only 25% of the NADH electrons were transferred to ROS. The YieF dimer may therefore be an obligatory four-electron chromate reducer which in one step transfers three electrons to chromate and one to molecular oxygen. As a mutant lacking this enzyme could not be obtained, the role of YieF in chromate protection could not be directly explored. The results nevertheless suggest that YieF may be an even more suitable candidate for further studies than ChrR.","Chromate-reducing properties of soluble flavoproteins from Pseudomonas putida and Escherichia coli Abs: Cr(VI) (chromate) is a toxic, soluble environmental contaminant. Bacteria can reduce chromate to the insoluble and less toxic Cr(III), and thus chromate bioremediation is of interest. Genetic and protein engineering of suitable enzymes can improve bacterial bioremediation. Many bacterial enzymes catalyze one-electron reduction of chromate, generating Cr(V), which redox cycles, generating excessive reactive oxygen species (ROS). Such enzymes are not appropriate for bioremediation, as they harm the bacteria and their primary end product is not Cr(III). In this work, the chromate reductase activities of two electrophoretically pure soluble bacterial flavoproteins--ChrR (from Pseudomonas putida) and YieF (from Escherichia coli)-were examined. Both are dimers and reduce chromate efficiently to Cr(III) (kcat/Km = approximately 2 x 10(4) M(-1) x s(-1)). The ChrR dimer generated a flavin semiquinone during chromate reduction and transferred &gt;25% of the NADH electrons to ROS. However, the semiquinone was formed transiently and ROS diminished with time. Thus, ChrR probably generates Cr(V), but only transiently. Studies with mutants showed that ChrR protects against chromate toxicity; this is possibly because it preempts chromate reduction by the cellular one-electron reducers, thereby minimizing ROS generation. ChrR is thus a suitable enzyme for further studies. During chromate reduction by YieF, no flavin semiquinone was generated and only 25% of the NADH electrons were transferred to ROS. The YieF dimer may therefore be an obligatory four-electron chromate reducer which in one step transfers three electrons to chromate and one to molecular oxygen. As a mutant lacking this enzyme could not be obtained, the role of YieF in chromate protection could not be directly explored. The results nevertheless suggest that YieF may be an even more suitable candidate for further studies than ChrR."
1235487,Gonçalves et al. 2003,Circulating blood volumes in pulmonary hypertension associated with erythrocytosis--the effects of therapeutic hemodilution,"In the Eisenmenger syndrome, indirect estimation of blood volumes may provide quite inaccurate information when seeking to define therapeutic strategies. With this in mind, we analyzed directly the red cell mass, plasma volume, and total blood volume in patients with pulmonary hypertension associated with congenital cardiac defects and erythrocytosis, comparing the results with the respective estimated volumes, and examining the changes induced by therapeutic hemodilution. Thus, we studied 17 patients with the Eisenmenger syndrome, aged from 15 to 53 years, in the basal condition, studying 12 of them both before and after hemodilution. We also investigated five individuals with minimal cardiac lesions, aged from 14 to 42 years, as controls. Red cell mass and plasma volumes were measured using [51chromium]-sodium chromate and [131iodine]-albumin respectively. Hemodilution was planned so as to exchange 10% of the total blood volume, using 40,000 molecular weight dextran simultaneously to replace the removed volume. The mean values of the red cell mass, plasma volume and total blood volume as assessed by radionuclide techniques were 32%, 31% and 32% higher than the respective volumes as estimated using empirical mathematical formulas (p &lt; 0.002). The measured total blood volume was also 19% higher in the patients compared with controls. Following a period of 5 days after hemodilution, we noted a 13% reduction in red cell mass (p = 0.046), and 10% reduction in total blood volume (p = 0.02), albeit with no changes in the plasma volume. We conclude that direct measurement of blood volumes is useful for proper management of these patients, and provides results that are considerably different from those obtained by empirical estimations.","Circulating blood volumes in pulmonary hypertension associated with erythrocytosis--the effects of therapeutic hemodilution Abs: In the Eisenmenger syndrome, indirect estimation of blood volumes may provide quite inaccurate information when seeking to define therapeutic strategies. With this in mind, we analyzed directly the red cell mass, plasma volume, and total blood volume in patients with pulmonary hypertension associated with congenital cardiac defects and erythrocytosis, comparing the results with the respective estimated volumes, and examining the changes induced by therapeutic hemodilution. Thus, we studied 17 patients with the Eisenmenger syndrome, aged from 15 to 53 years, in the basal condition, studying 12 of them both before and after hemodilution. We also investigated five individuals with minimal cardiac lesions, aged from 14 to 42 years, as controls. Red cell mass and plasma volumes were measured using [51chromium]-sodium chromate and [131iodine]-albumin respectively. Hemodilution was planned so as to exchange 10% of the total blood volume, using 40,000 molecular weight dextran simultaneously to replace the removed volume. The mean values of the red cell mass, plasma volume and total blood volume as assessed by radionuclide techniques were 32%, 31% and 32% higher than the respective volumes as estimated using empirical mathematical formulas (p &lt; 0.002). The measured total blood volume was also 19% higher in the patients compared with controls. Following a period of 5 days after hemodilution, we noted a 13% reduction in red cell mass (p = 0.046), and 10% reduction in total blood volume (p = 0.02), albeit with no changes in the plasma volume. We conclude that direct measurement of blood volumes is useful for proper management of these patients, and provides results that are considerably different from those obtained by empirical estimations."
1235486,Hodges et al. 2004,Activation of c-Jun N-terminal kinase in A549 lung carcinoma cells by sodium dichromate: role of dissociation of apoptosis signal regulating kinase-1 from its physiological inhibitor thioredoxin,"Changes in the components of the Jun N-terminal kinase (JNK) signalling pathway were investigated in human A549 lung carcinoma cells treated with sodium dichromate. Sodium dichromate (100 microM, 0-6h) failed to activate nuclear factor kappa B (NF-kappaB) as determined by a lack of nuclear translocation of p65 but resulted in Jun N-terminal kinase activation as assessed by phospho-Jun N-terminal kinase Western blotting in a dose-dependent (&gt;25 microM) and time-dependent (&gt;1h) manner. In addition, c-Jun, a downstream target of Jun N-terminal kinase signalling was also activated with a similar dose- and time-dependency at the level of both protein expression and degree of phosphorylation. In contrast, sodium dichromate treatment had no effect on levels of phospho-p38. Immunoprecipitation demonstrated that apoptosis signal regulating kinase-1 (ASK-1), an upstream activator of Jun N-terminal kinase was dissociated from its inhibitory partner thioredoxin (Trx) in response to sodium dichromate (100 microM, 4h) treatment. This treatment was also associated with a transient (2h) increase in cytosolic levels of thioredoxin but no nuclear translocation of thioredoxin was observed. In conclusion, sodium dichromate had a stimulatory effect on the Jun N-terminal kinase signalling pathway in A549 cells, resulting in activation of downstream effector molecules. We hypothesise that dissociation of apoptosis signal regulating kinase-1 from thioredoxin may be at least partially responsible for Jun N-terminal kinase activation.","Activation of c-Jun N-terminal kinase in A549 lung carcinoma cells by sodium dichromate: role of dissociation of apoptosis signal regulating kinase-1 from its physiological inhibitor thioredoxin Abs: Changes in the components of the Jun N-terminal kinase (JNK) signalling pathway were investigated in human A549 lung carcinoma cells treated with sodium dichromate. Sodium dichromate (100 microM, 0-6h) failed to activate nuclear factor kappa B (NF-kappaB) as determined by a lack of nuclear translocation of p65 but resulted in Jun N-terminal kinase activation as assessed by phospho-Jun N-terminal kinase Western blotting in a dose-dependent (&gt;25 microM) and time-dependent (&gt;1h) manner. In addition, c-Jun, a downstream target of Jun N-terminal kinase signalling was also activated with a similar dose- and time-dependency at the level of both protein expression and degree of phosphorylation. In contrast, sodium dichromate treatment had no effect on levels of phospho-p38. Immunoprecipitation demonstrated that apoptosis signal regulating kinase-1 (ASK-1), an upstream activator of Jun N-terminal kinase was dissociated from its inhibitory partner thioredoxin (Trx) in response to sodium dichromate (100 microM, 4h) treatment. This treatment was also associated with a transient (2h) increase in cytosolic levels of thioredoxin but no nuclear translocation of thioredoxin was observed. In conclusion, sodium dichromate had a stimulatory effect on the Jun N-terminal kinase signalling pathway in A549 cells, resulting in activation of downstream effector molecules. We hypothesise that dissociation of apoptosis signal regulating kinase-1 from thioredoxin may be at least partially responsible for Jun N-terminal kinase activation."
1235483,Reynolds et al. 2004,Human nucleotide excision repair efficiently removes chromium-DNA phosphate adducts and protects cells against chromate toxicity,"Intracellular reduction of carcinogenic Cr(VI) leads to the extensive formation of Cr(III)-DNA phosphate adducts. Repair mechanisms for chromium and other DNA phosphate-based adducts are currently unknown in human cells. We found that nucleotide excision repair (NER)-proficient human cells rapidly removed chromium-DNA adducts, with an average t((1/2)) of 7.1 h, whereas NER-deficient XP-A, XP-C, and XP-F cells were severely compromised in their ability to repair chromium-DNA lesions. Activation of NER in Cr(VI)-treated human fibroblasts or lung epithelial H460 cells was manifested by XPC-dependent binding of the XPA protein to the nuclear matrix, which was also observed in UV light-treated (but not oxidant-stressed) cells. Intracellular replication of chromium-modified plasmids demonstrated increased mutagenicity of binary Cr(III)-DNA and ternary cysteine-Cr(III)-DNA adducts in cells with inactive NER. NER deficiency created by the loss of XPA in fibroblasts or by knockdown of this protein by stable expression of small interfering RNA in H460 cells increased apoptosis and clonogenic death by Cr(VI), providing genetic evidence for the role of monofunctional chromium-DNA adducts in the toxic effects of this metal. The rate of NER of chromium-DNA adducts under saturating conditions was calculated to be approximately 50,000 lesions/min/cell. Because chromium-DNA adducts cause only small changes in the DNA helix, rapid repair of these modifications in human cells indicates that the presence of major structural distortions in DNA is not required for the efficient detection of the damaged sites by NER proteins in vivo.","Human nucleotide excision repair efficiently removes chromium-DNA phosphate adducts and protects cells against chromate toxicity Abs: Intracellular reduction of carcinogenic Cr(VI) leads to the extensive formation of Cr(III)-DNA phosphate adducts. Repair mechanisms for chromium and other DNA phosphate-based adducts are currently unknown in human cells. We found that nucleotide excision repair (NER)-proficient human cells rapidly removed chromium-DNA adducts, with an average t((1/2)) of 7.1 h, whereas NER-deficient XP-A, XP-C, and XP-F cells were severely compromised in their ability to repair chromium-DNA lesions. Activation of NER in Cr(VI)-treated human fibroblasts or lung epithelial H460 cells was manifested by XPC-dependent binding of the XPA protein to the nuclear matrix, which was also observed in UV light-treated (but not oxidant-stressed) cells. Intracellular replication of chromium-modified plasmids demonstrated increased mutagenicity of binary Cr(III)-DNA and ternary cysteine-Cr(III)-DNA adducts in cells with inactive NER. NER deficiency created by the loss of XPA in fibroblasts or by knockdown of this protein by stable expression of small interfering RNA in H460 cells increased apoptosis and clonogenic death by Cr(VI), providing genetic evidence for the role of monofunctional chromium-DNA adducts in the toxic effects of this metal. The rate of NER of chromium-DNA adducts under saturating conditions was calculated to be approximately 50,000 lesions/min/cell. Because chromium-DNA adducts cause only small changes in the DNA helix, rapid repair of these modifications in human cells indicates that the presence of major structural distortions in DNA is not required for the efficient detection of the damaged sites by NER proteins in vivo."
1235478,Sullivan and  Douek 2004,"Analysis of hydroxide, inorganic sulphur species and organic anions in kraft pulping liquors by capillary electrophoresis","A new method has been developed for the determination of hydroxide, sulphide, thiosulphate, sulphate, sulphite, chloride, oxalate and formate in kraft green, white and black liquors by capillary electrophoresis. The method provides baseline resolution of all analytes of interest using an electrolyte composed of 10 mM sodium chromate and 2 mM tetradecyltrimethylammonium hydroxide. Separations are conducted under constant current conditions at 25 degrees C and analytes are quantified by indirect UV-detection at 275 nm. A brief, post run wash of the capillary with 0.5 M NaOH and water gave improved inter- and intra-run repeatability of both migration times and peak areas. Sulphide and other oxysulphur species were relatively stable in white and green liquors diluted in helium-sparged water. However, sulphide present in black liquor samples diluted in the same solvent underwent rapid oxidation to form sulphite and thiosulphate. thereby precluding the measurement of all three anions. We discovered that quinone-type compounds present in black liquor catalyze the oxidation of sulphide and that the addition of reduced glutathione at a concentration of I mg/mL during black liquor dilution completely stabilized sulphide, sulphite and thiosulphate for at least one hour, thus allowing for quantitative analysis of the analytes. A mechanism is proposed to explain the action of both quinones and that of glutathione. Results obtained by the new method compared well with those obtained by ion chromatography, titrimetry, and from spike-recovery experiments.","Analysis of hydroxide, inorganic sulphur species and organic anions in kraft pulping liquors by capillary electrophoresis Abs: A new method has been developed for the determination of hydroxide, sulphide, thiosulphate, sulphate, sulphite, chloride, oxalate and formate in kraft green, white and black liquors by capillary electrophoresis. The method provides baseline resolution of all analytes of interest using an electrolyte composed of 10 mM sodium chromate and 2 mM tetradecyltrimethylammonium hydroxide. Separations are conducted under constant current conditions at 25 degrees C and analytes are quantified by indirect UV-detection at 275 nm. A brief, post run wash of the capillary with 0.5 M NaOH and water gave improved inter- and intra-run repeatability of both migration times and peak areas. Sulphide and other oxysulphur species were relatively stable in white and green liquors diluted in helium-sparged water. However, sulphide present in black liquor samples diluted in the same solvent underwent rapid oxidation to form sulphite and thiosulphate. thereby precluding the measurement of all three anions. We discovered that quinone-type compounds present in black liquor catalyze the oxidation of sulphide and that the addition of reduced glutathione at a concentration of I mg/mL during black liquor dilution completely stabilized sulphide, sulphite and thiosulphate for at least one hour, thus allowing for quantitative analysis of the analytes. A mechanism is proposed to explain the action of both quinones and that of glutathione. Results obtained by the new method compared well with those obtained by ion chromatography, titrimetry, and from spike-recovery experiments."
1235477,Ackerley et al. 2004,"Mechanism of chromate reduction by the Escherichia coli protein, NfsA, and the role of different chromate reductases in minimizing oxidative stress during chromate reduction","Chromate [Cr(VI)] is a serious environmental pollutant, which is amenable to bacterial bioremediation. NfsA, the major oxygen-insensitive nitroreductase of Escherichia coli, is a flavoprotein that is able to reduce chromate to less soluble and less toxic Cr(III). We show that this process involves single-electron transfer, giving rise to a flavin semiquinone form of NfsA and Cr(V) as intermediates, which redox cycle, generating more reactive oxygen species (ROS) than a divalent chromate reducer, YieF. However, NfsA generates less ROS than a known one-electron chromate reducer, lipoyl dehydrogenase (LpDH), suggesting that NfsA employs a mixture of uni- and di-valent electron transfer steps. The presence of YieF, ChrR (another chromate reductase we previously characterized), or NfsA in an LpDH-catalysed chromate reduction reaction decreased ROS generation by c. 65, 40, or 20%, respectively, suggesting that these enzymes can pre-empt ROS generation by LpDH. We previously showed that ChrR protects Pseudomonas putida against chromate toxicity; here we show that NfsA or YieF overproduction can also increase the tolerance of E. coli to this compound.","Mechanism of chromate reduction by the Escherichia coli protein, NfsA, and the role of different chromate reductases in minimizing oxidative stress during chromate reduction Abs: Chromate [Cr(VI)] is a serious environmental pollutant, which is amenable to bacterial bioremediation. NfsA, the major oxygen-insensitive nitroreductase of Escherichia coli, is a flavoprotein that is able to reduce chromate to less soluble and less toxic Cr(III). We show that this process involves single-electron transfer, giving rise to a flavin semiquinone form of NfsA and Cr(V) as intermediates, which redox cycle, generating more reactive oxygen species (ROS) than a divalent chromate reducer, YieF. However, NfsA generates less ROS than a known one-electron chromate reducer, lipoyl dehydrogenase (LpDH), suggesting that NfsA employs a mixture of uni- and di-valent electron transfer steps. The presence of YieF, ChrR (another chromate reductase we previously characterized), or NfsA in an LpDH-catalysed chromate reduction reaction decreased ROS generation by c. 65, 40, or 20%, respectively, suggesting that these enzymes can pre-empt ROS generation by LpDH. We previously showed that ChrR protects Pseudomonas putida against chromate toxicity; here we show that NfsA or YieF overproduction can also increase the tolerance of E. coli to this compound."
1235476,George et al. 2004,"Stability, antigenicity, and aggregation of Moraxella bovis cytolysin after purification and storage","<strong>OBJECTIVES: </strong>To compare stability, antigenicity, and aggregation characteristics of Moraxella bovis cytolysins among isolates from geographically diverse areas.<br /><br /><strong>STUDY POPULATION: </strong>8 isolates of M. bovis.<br /><br /><strong>PROCEDURE: </strong>Filter-sterilized broth culture supernatants of M. bovis were concentrated, diafiltered, and chromatographed. The endotoxin and cytolysin activities in samples were measured. Chromatographed cytolysins of M. bovis were examined by immunoblotting. Hemolytic and leukotoxic activities were measured from samples collected at each step of purification and before and after storage. Hemolysis was measured directly by use of washed bovine erythrocyte targets. Leukotoxicity was measured by use of a 51Cr release assay.<br /><br /><strong>RESULTS: </strong>Cytolysin was retained by a filter with 100-kd nominal molecular weight limit. Hemolytic activity, leukotoxic activity, and endotoxin were eluted together in void volume of a gel-filtration column (molecular mass exclusion limit = 4 X 10(7) d). Gel-column chromatographed diafiltered retentate had the greatest specific cytolytic activity and the highest endotoxin-to-protein ratio. Frozen diafiltered retentate(-80 degrees C, 4 months) was cytolytic after thawing. Immunoblots of gel-column chromatographed cytolysin contained 4 proteins with molecular masses between 90 and 68 kd. Fractions with high lytic activities also had additional protein bands with molecular masses of 98 and 63 kd. Immunoblots of gel-column chromatographed diafiltered retentate revealed proteins with molecular masses between 90 and 68 kd.<br /><br /><strong>CONCLUSIONS AND CLINICAL RELEVANCE: </strong>Diafiltered M. bovis cytolysin is aggregated with endotoxin. Antigenicity and cytolytic activities in diafiltered retentate are conserved among M. bovis isolates. Diafiltration could be useful for bulk semipurification of M. bovis cytolysin. Cytolysin-enriched vaccines of M. bovis could be contaminated by endotoxin.","Stability, antigenicity, and aggregation of Moraxella bovis cytolysin after purification and storage Abs: <strong>OBJECTIVES: </strong>To compare stability, antigenicity, and aggregation characteristics of Moraxella bovis cytolysins among isolates from geographically diverse areas.<br /><br /><strong>STUDY POPULATION: </strong>8 isolates of M. bovis.<br /><br /><strong>PROCEDURE: </strong>Filter-sterilized broth culture supernatants of M. bovis were concentrated, diafiltered, and chromatographed. The endotoxin and cytolysin activities in samples were measured. Chromatographed cytolysins of M. bovis were examined by immunoblotting. Hemolytic and leukotoxic activities were measured from samples collected at each step of purification and before and after storage. Hemolysis was measured directly by use of washed bovine erythrocyte targets. Leukotoxicity was measured by use of a 51Cr release assay.<br /><br /><strong>RESULTS: </strong>Cytolysin was retained by a filter with 100-kd nominal molecular weight limit. Hemolytic activity, leukotoxic activity, and endotoxin were eluted together in void volume of a gel-filtration column (molecular mass exclusion limit = 4 X 10(7) d). Gel-column chromatographed diafiltered retentate had the greatest specific cytolytic activity and the highest endotoxin-to-protein ratio. Frozen diafiltered retentate(-80 degrees C, 4 months) was cytolytic after thawing. Immunoblots of gel-column chromatographed cytolysin contained 4 proteins with molecular masses between 90 and 68 kd. Fractions with high lytic activities also had additional protein bands with molecular masses of 98 and 63 kd. Immunoblots of gel-column chromatographed diafiltered retentate revealed proteins with molecular masses between 90 and 68 kd.<br /><br /><strong>CONCLUSIONS AND CLINICAL RELEVANCE: </strong>Diafiltered M. bovis cytolysin is aggregated with endotoxin. Antigenicity and cytolytic activities in diafiltered retentate are conserved among M. bovis isolates. Diafiltration could be useful for bulk semipurification of M. bovis cytolysin. Cytolysin-enriched vaccines of M. bovis could be contaminated by endotoxin."
1235475,Halim et al. 2004,"Comparison between acetic acid and landfill leachates for the leaching of Pb(II), Cd(II), As(V), and Cr(VI) from cementitious wastes","The Toxicity Characteristic Leaching Procedure (TCLP) has been widely used to characterize the suitability of solid wastes for disposal in landfills. However, the widespread application of this test for the assessment of wastes disposed in different landfill types is often questionable. This paper investigates the leaching profiles of cement-stabilized heavy metal ions, namely, Pb (II), Cd (II), As(V), and Cr(VI), using acetic acid and leachates from municipal and nonputrescible Australian landfill sites. The leaching profiles of Pb, Cd, As, and Cr using acetic acid were found to be similar to the nonputrescible landfill leachate and differed markedly from the municipal solid waste (MSW) leachate. The additional presence of high amounts of organic and inorganic compounds in the municipal landfill leachate influenced the leaching profiles of these metal ions as compared to the acetic acid and the nonputrescible systems. It is postulated that the organic compounds present in the municipal landfill leachate formed complexes with the Pb and Cd, increasing the mobility of these ions. Moreover, the organic compounds in the municipal landfill leachate induced a reducing environment in the leachate, causing the reduction of Cr(VI) to Cr(III). It was also found that the presence of carbonates in the municipal landfill leachate affected the stability of calcium arsenate, with the carbonate competing with arsenate for calcium at high pH, forcing arsenate into the solution.","Comparison between acetic acid and landfill leachates for the leaching of Pb(II), Cd(II), As(V), and Cr(VI) from cementitious wastes Abs: The Toxicity Characteristic Leaching Procedure (TCLP) has been widely used to characterize the suitability of solid wastes for disposal in landfills. However, the widespread application of this test for the assessment of wastes disposed in different landfill types is often questionable. This paper investigates the leaching profiles of cement-stabilized heavy metal ions, namely, Pb (II), Cd (II), As(V), and Cr(VI), using acetic acid and leachates from municipal and nonputrescible Australian landfill sites. The leaching profiles of Pb, Cd, As, and Cr using acetic acid were found to be similar to the nonputrescible landfill leachate and differed markedly from the municipal solid waste (MSW) leachate. The additional presence of high amounts of organic and inorganic compounds in the municipal landfill leachate influenced the leaching profiles of these metal ions as compared to the acetic acid and the nonputrescible systems. It is postulated that the organic compounds present in the municipal landfill leachate formed complexes with the Pb and Cd, increasing the mobility of these ions. Moreover, the organic compounds in the municipal landfill leachate induced a reducing environment in the leachate, causing the reduction of Cr(VI) to Cr(III). It was also found that the presence of carbonates in the municipal landfill leachate affected the stability of calcium arsenate, with the carbonate competing with arsenate for calcium at high pH, forcing arsenate into the solution."
1235474,Todorovi?-Tirnani? et al. 2004,Clinical significance of optimal red cell mass and plasma volume estimation methods,"<strong>BACKGROUND: </strong>The aim of this study was to present and compare the results of proposed methods for optimal red cell mass and plasma volume (RCM&amp;PV) estimation, and their influence on the interpretation of obtained results.<br /><br /><strong>MATERIAL AND METHODS: </strong>In 120/280 patients with polycythaemia rubra vera, subjected to RCM&amp;PV determination with autologous erythrocytes in vitro labelled with 51Cr-sodium chromate, optimal volumes were determined using: 1. traditional ml/kg of: --the real body weight method (ml/kg RBW); --the optimal body weight method (ml/kg OBW). 2. the body weight, height, and sex based method (Retzlaff's tables), 3. the method recommended by the International Council for Standardization in Haematology (ICSH), based on body surface area.<br /><br /><strong>RESULTS: </strong>Different interpretation of the same results of 120 RCM&amp;PV measurements was registered in 48/120 patients (40%). The greatest disagreement existed between ml/kg RBW and ml/kg OBW methods (in 39/120 subjects, 32.5%). In underweight patients the ml/kg RBW method, and in overweight patients the ml/kg OBW method, offered better agreement with ICSH&amp;Retzlaff's methods. The ml/kg RBW method disagreed with ICSH&amp;Retzlaff's methods and ml/kg OBW in 25% and 19.2% of patients respectively. ICSH and Retzlaff's methods disagreed in 10/120 patients (8.3%). The ICSH method yielded significantly lower optimal volumes than Retzlaff's.<br /><br /><strong>CONCLUSION: </strong>Three methods for optimal RCM&amp;PV estimation lead to different interpretations of the same results of RCM&amp;PV measurements with 51Cr-erythrocytes in 40% of patients. Two ml/kg body weight methods show greater disagreement in comparison with ICSH and Retzlaff's methods, which differ significantly. The ICSH method yields lower optimal values compared to Retzlaff's.","Clinical significance of optimal red cell mass and plasma volume estimation methods Abs: <strong>BACKGROUND: </strong>The aim of this study was to present and compare the results of proposed methods for optimal red cell mass and plasma volume (RCM&amp;PV) estimation, and their influence on the interpretation of obtained results.<br /><br /><strong>MATERIAL AND METHODS: </strong>In 120/280 patients with polycythaemia rubra vera, subjected to RCM&amp;PV determination with autologous erythrocytes in vitro labelled with 51Cr-sodium chromate, optimal volumes were determined using: 1. traditional ml/kg of: --the real body weight method (ml/kg RBW); --the optimal body weight method (ml/kg OBW). 2. the body weight, height, and sex based method (Retzlaff's tables), 3. the method recommended by the International Council for Standardization in Haematology (ICSH), based on body surface area.<br /><br /><strong>RESULTS: </strong>Different interpretation of the same results of 120 RCM&amp;PV measurements was registered in 48/120 patients (40%). The greatest disagreement existed between ml/kg RBW and ml/kg OBW methods (in 39/120 subjects, 32.5%). In underweight patients the ml/kg RBW method, and in overweight patients the ml/kg OBW method, offered better agreement with ICSH&amp;Retzlaff's methods. The ml/kg RBW method disagreed with ICSH&amp;Retzlaff's methods and ml/kg OBW in 25% and 19.2% of patients respectively. ICSH and Retzlaff's methods disagreed in 10/120 patients (8.3%). The ICSH method yielded significantly lower optimal volumes than Retzlaff's.<br /><br /><strong>CONCLUSION: </strong>Three methods for optimal RCM&amp;PV estimation lead to different interpretations of the same results of RCM&amp;PV measurements with 51Cr-erythrocytes in 40% of patients. Two ml/kg body weight methods show greater disagreement in comparison with ICSH and Retzlaff's methods, which differ significantly. The ICSH method yields lower optimal values compared to Retzlaff's."
1235471,Ly et al. 2004,Red blood cell survival in chronic renal failure,"<strong>BACKGROUND: </strong>A decrease in the lifespan of erythrocytes has been accepted universally as one of the contributory factors to anemia in patients with chronic renal failure. This observation was made in the 1950s and 1960s when continuous renal replacement therapy was at its infancy. Based on the premise that a reduced red blood cell (RBC) lifespan in renal disease is primarily caused by the toxic uremic milieu, the purpose of this study is 2-fold: to compare the RBC survival in today's renal patients with that in the existing literature and to explore if there are differential RBC survival benefits with various dialysis dosages.<br /><br /><strong>METHODS: </strong>This is an observational study. Patients with end-stage renal disease were recruited from the dialysis program at the University Health Network and St Michael's Hospital in Toronto. The patients were stratified into 3 groups including conventional thrice-weekly, nocturnal, and short-daily hemodialysis. Healthy subjects were recruited to validate the normal range for RBC lifespan. Red cell survival was assessed using radiolabeled sodium chromate (Na2 51CrO4).<br /><br /><strong>RESULTS: </strong>Twenty-two patients and 2 healthy control subjects were recruited. The average red cell half-lives in thrice-weekly, nocturnal, short-daily, and healthy subjects were 14.5 +/- 1.6, 17.1 +/- 4.7, 15.9 +/- 2.2, and 23.5 days, respectively. All 3 patient groups exhibited reduced RBC lifespan (P &lt; 0.05). Further, the overall RBC lifespan was not different from that reported half a century ago. Despite better urea clearances among the nocturnal and short-daily dialysis groups, no RBC survival benefit was observed.<br /><br /><strong>CONCLUSION: </strong>A reduced RBC lifespan continues to contribute to renal anemia despite technologic advancements and improved uremic environment.","Red blood cell survival in chronic renal failure Abs: <strong>BACKGROUND: </strong>A decrease in the lifespan of erythrocytes has been accepted universally as one of the contributory factors to anemia in patients with chronic renal failure. This observation was made in the 1950s and 1960s when continuous renal replacement therapy was at its infancy. Based on the premise that a reduced red blood cell (RBC) lifespan in renal disease is primarily caused by the toxic uremic milieu, the purpose of this study is 2-fold: to compare the RBC survival in today's renal patients with that in the existing literature and to explore if there are differential RBC survival benefits with various dialysis dosages.<br /><br /><strong>METHODS: </strong>This is an observational study. Patients with end-stage renal disease were recruited from the dialysis program at the University Health Network and St Michael's Hospital in Toronto. The patients were stratified into 3 groups including conventional thrice-weekly, nocturnal, and short-daily hemodialysis. Healthy subjects were recruited to validate the normal range for RBC lifespan. Red cell survival was assessed using radiolabeled sodium chromate (Na2 51CrO4).<br /><br /><strong>RESULTS: </strong>Twenty-two patients and 2 healthy control subjects were recruited. The average red cell half-lives in thrice-weekly, nocturnal, short-daily, and healthy subjects were 14.5 +/- 1.6, 17.1 +/- 4.7, 15.9 +/- 2.2, and 23.5 days, respectively. All 3 patient groups exhibited reduced RBC lifespan (P &lt; 0.05). Further, the overall RBC lifespan was not different from that reported half a century ago. Despite better urea clearances among the nocturnal and short-daily dialysis groups, no RBC survival benefit was observed.<br /><br /><strong>CONCLUSION: </strong>A reduced RBC lifespan continues to contribute to renal anemia despite technologic advancements and improved uremic environment."
1235468,Pourahmad et al. 2005,A comparison of hepatocyte cytotoxic mechanisms for chromate and arsenite,"In the following, we have compared the cytotoxic mechanisms of the chromate CrO(4)(2-) and arsenite AsO(2)(-). Chromate (Cr (VI)) cytotoxicity was associated with reactive oxygen species (ROS) formation, lipid peroxidation and loss of mitochondrial membrane potential, which were prevented by catalase, antioxidants and ROS scavengers. Hepatocyte glutathione was also rapidly oxidized. Chromate reduction was inhibited in glutathione depleted hepatocytes, and glutathione depleted hepatocytes were also much more resistant to chromate induced cytotoxicity, ROS formation and lipid peroxidation. This suggests that chromate is reductively activated by glutathione. Chromate cytotoxicity also involved lysosomal injury and protease activation, which were prevented by lysosomotropic agents, endocytosis inhibitors, protease inhibitors and ROS scavengers. On the other hand, arsenite cytotoxicity was associated with much less oxidative stress, and lysosomal damage did not occur. However, arsenite cytotoxicity was also associated with loss of mitochondrial membrane potential, which in contrast to chromate cytotoxicity was inhibited by the ATP generators fructose, xylitol and glutamine. Arsenite induced cytotoxicity, mitochondrial membrane potential decline and also ROS formation were significantly increased by inactivating hepatocyte methionine synthase or hepatocyte methyl transferase. However, methyl donors such as betaine, methionine or folic acid prevented arsenite but not chromate cytotoxicity, and this suggests that arsenite is detoxified by reductive methylation. In conclusion, chromate induced cytotoxicity could be attributed to oxidative stress and lysosomal damage, whereas arsenite induced cytotoxicity could be attributed to mitochondrial toxicity and ATP depletion.","A comparison of hepatocyte cytotoxic mechanisms for chromate and arsenite Abs: In the following, we have compared the cytotoxic mechanisms of the chromate CrO(4)(2-) and arsenite AsO(2)(-). Chromate (Cr (VI)) cytotoxicity was associated with reactive oxygen species (ROS) formation, lipid peroxidation and loss of mitochondrial membrane potential, which were prevented by catalase, antioxidants and ROS scavengers. Hepatocyte glutathione was also rapidly oxidized. Chromate reduction was inhibited in glutathione depleted hepatocytes, and glutathione depleted hepatocytes were also much more resistant to chromate induced cytotoxicity, ROS formation and lipid peroxidation. This suggests that chromate is reductively activated by glutathione. Chromate cytotoxicity also involved lysosomal injury and protease activation, which were prevented by lysosomotropic agents, endocytosis inhibitors, protease inhibitors and ROS scavengers. On the other hand, arsenite cytotoxicity was associated with much less oxidative stress, and lysosomal damage did not occur. However, arsenite cytotoxicity was also associated with loss of mitochondrial membrane potential, which in contrast to chromate cytotoxicity was inhibited by the ATP generators fructose, xylitol and glutamine. Arsenite induced cytotoxicity, mitochondrial membrane potential decline and also ROS formation were significantly increased by inactivating hepatocyte methionine synthase or hepatocyte methyl transferase. However, methyl donors such as betaine, methionine or folic acid prevented arsenite but not chromate cytotoxicity, and this suggests that arsenite is detoxified by reductive methylation. In conclusion, chromate induced cytotoxicity could be attributed to oxidative stress and lysosomal damage, whereas arsenite induced cytotoxicity could be attributed to mitochondrial toxicity and ATP depletion."
1235466,Wu et al. 2005,Studies on the acute biochemical effects of La(NO3)3 using 1H NMR spectroscopy of urine combined with pattern recognition,"(1)H NMR spectroscopic and pattern recognition-based methods were applied to the studies on the acute biochemical effects of La(NO(3))(3). Male Wistar rats were separated into groups (n=10) and each was treated with one of following compounds, sodium chromate (NaCrO(4)), mercury II chloride (HgCl(2)), 2-bromoethanamine hydrobromide (BEA), carbon tetrachloride (CCl(4)), hydrazine (HYD), alpha-naphthylisothiocyanate (ANIT), and three doses of La(NO(3))(3). Urine samples were collected over a 48-h time course and measured by 600 MHz NMR spectroscopy. Each spectrum was data-processed to provide 205 intensity-related descriptors used as input coordinates in a multidimensional space and analyzed by pattern recognition method. By NMR and principal components analysis (PCA) methods, the biochemical effects classification and time-course trajectories of various doses of La(NO(3))(3) were achieved. The toxicity of La(NO(3))(3) was similar to that of carbon tetrachloride according to the (1)H NMR spectral profiles and toxicity classification. This work illustrates the high reliability of NMR-PR method using (1)H NMR spectroscopy for the exploration and prediction of biochemical effects of rare earths in rats.","Studies on the acute biochemical effects of La(NO3)3 using 1H NMR spectroscopy of urine combined with pattern recognition Abs: (1)H NMR spectroscopic and pattern recognition-based methods were applied to the studies on the acute biochemical effects of La(NO(3))(3). Male Wistar rats were separated into groups (n=10) and each was treated with one of following compounds, sodium chromate (NaCrO(4)), mercury II chloride (HgCl(2)), 2-bromoethanamine hydrobromide (BEA), carbon tetrachloride (CCl(4)), hydrazine (HYD), alpha-naphthylisothiocyanate (ANIT), and three doses of La(NO(3))(3). Urine samples were collected over a 48-h time course and measured by 600 MHz NMR spectroscopy. Each spectrum was data-processed to provide 205 intensity-related descriptors used as input coordinates in a multidimensional space and analyzed by pattern recognition method. By NMR and principal components analysis (PCA) methods, the biochemical effects classification and time-course trajectories of various doses of La(NO(3))(3) were achieved. The toxicity of La(NO(3))(3) was similar to that of carbon tetrachloride according to the (1)H NMR spectral profiles and toxicity classification. This work illustrates the high reliability of NMR-PR method using (1)H NMR spectroscopy for the exploration and prediction of biochemical effects of rare earths in rats."
1235460,Santoyo et al. 2005,Evaluation of capillary electrophoresis for determining the concentration of dissolved silica in geothermal brines,"The determination of silica concentrations in geothermal brines is widely recognized as a difficult analytical task due to its complex chemical polymerization kinetics that occurs during sample collection and chemical analysis. Capillary electrophoresis (CE) has been evaluated as a new reliable analytical method to measure silica (as silicates) in geothermal brines. Synthetic and geothermal brine samples were used to evaluate CE methodology. A capillary electrophoresis instrument, Quanta 4000 (Waters-Millipore) coupled with a Waters 820 workstation was used to carry out the experimental work. The separation of silicates was completed in approximately 5.5 min using a conventional fused-silica capillary (75 microm i.d. x 375 microm o.d. x 60 cm total length). A hydrostatic injection (10 cm for 20 s at 25 degrees C) was employed for introducing the samples. The carrier electrolyte consisted of 10 mM sodium chromate, 3 mM tetradecyltrimethyl-ammonium hydroxide (TTAOH), 2 mM sodium carbonate, and 1 mM sodium hydroxide, adjusted to a pH 11.0 +/- 0.1. Silicates were determined using an indirect UV detection at a wavelength of 254 nm with a mercury lamp and with a negative power supply (-15 kV). A good reproducibility in the migration times (%R.S.D. approximately 1.6%) based on six non-consecutive injections of synthetic brine solutions was obtained. A linear response between silica concentration and corrected peak area was observed. Ordinary (OLR) and weighted (WLR) linear regression models were used for calculating silica concentrations in all samples using the corresponding fitted calibration curves. The analytical results of CE were finally compared with the most probable values of synthetic reference standards of silica using the Student's t-test. No significant differences were found between them at P = 0.01. Similarly, the atomic absorption spectrometry (AAS) results were also compared with the most probable concentrations of the same reference standards, finding significant differences at P = 0.01.","Evaluation of capillary electrophoresis for determining the concentration of dissolved silica in geothermal brines Abs: The determination of silica concentrations in geothermal brines is widely recognized as a difficult analytical task due to its complex chemical polymerization kinetics that occurs during sample collection and chemical analysis. Capillary electrophoresis (CE) has been evaluated as a new reliable analytical method to measure silica (as silicates) in geothermal brines. Synthetic and geothermal brine samples were used to evaluate CE methodology. A capillary electrophoresis instrument, Quanta 4000 (Waters-Millipore) coupled with a Waters 820 workstation was used to carry out the experimental work. The separation of silicates was completed in approximately 5.5 min using a conventional fused-silica capillary (75 microm i.d. x 375 microm o.d. x 60 cm total length). A hydrostatic injection (10 cm for 20 s at 25 degrees C) was employed for introducing the samples. The carrier electrolyte consisted of 10 mM sodium chromate, 3 mM tetradecyltrimethyl-ammonium hydroxide (TTAOH), 2 mM sodium carbonate, and 1 mM sodium hydroxide, adjusted to a pH 11.0 +/- 0.1. Silicates were determined using an indirect UV detection at a wavelength of 254 nm with a mercury lamp and with a negative power supply (-15 kV). A good reproducibility in the migration times (%R.S.D. approximately 1.6%) based on six non-consecutive injections of synthetic brine solutions was obtained. A linear response between silica concentration and corrected peak area was observed. Ordinary (OLR) and weighted (WLR) linear regression models were used for calculating silica concentrations in all samples using the corresponding fitted calibration curves. The analytical results of CE were finally compared with the most probable values of synthetic reference standards of silica using the Student's t-test. No significant differences were found between them at P = 0.01. Similarly, the atomic absorption spectrometry (AAS) results were also compared with the most probable concentrations of the same reference standards, finding significant differences at P = 0.01."
1235457,Miranda et al. 2005,Involvement of DNA helicases in chromate resistance by Pseudomonas aeruginosa PAO1,"Chromate-hypersensitive mutants of the Pseudomonas aeruginosa PAO1 strain were isolated using transposon insertion mutagenesis. Comparison of the nucleotide sequences of the regions interrupted within the PAO1 genome showed that mutant strains GGP-64 and AJ-22 were affected in open reading frames PA0967 and PA5345, which correspond to the ruvB and recG genes, respectively. These genes encode helicases RuvB and RecG involved in DNA replication, recombination and repair. The chromate resistance phenotype in mutants GGP-64 and AJ-22 was restored by cosmids bearing wild type ruvB or recG genes, respectively. Also, both mutant strains showed an increased susceptibility to the toxic oxyanions tellurite and selenite as well as to mitomycin C, but not to arsenite, paraquat and hydrogen peroxide. It was concluded that P. aeruginosa RuvB and RecG helicases are involved in repairing DNA damage caused by chromate or its derivatives.","Involvement of DNA helicases in chromate resistance by Pseudomonas aeruginosa PAO1 Abs: Chromate-hypersensitive mutants of the Pseudomonas aeruginosa PAO1 strain were isolated using transposon insertion mutagenesis. Comparison of the nucleotide sequences of the regions interrupted within the PAO1 genome showed that mutant strains GGP-64 and AJ-22 were affected in open reading frames PA0967 and PA5345, which correspond to the ruvB and recG genes, respectively. These genes encode helicases RuvB and RecG involved in DNA replication, recombination and repair. The chromate resistance phenotype in mutants GGP-64 and AJ-22 was restored by cosmids bearing wild type ruvB or recG genes, respectively. Also, both mutant strains showed an increased susceptibility to the toxic oxyanions tellurite and selenite as well as to mitomycin C, but not to arsenite, paraquat and hydrogen peroxide. It was concluded that P. aeruginosa RuvB and RecG helicases are involved in repairing DNA damage caused by chromate or its derivatives."
1235455,Takahashi et al. 2005,Microscopic analysis of the chromium content in the chromium-induced malignant and premalignant bronchial lesions of the rat,"<strong>OBJECTIVE: </strong>Our previous studies demonstrated that the frequency of gene instability in lung cancer of chromate workers was very high, but the frequencies of the p53 and ras gene mutations were low. To clarify the carcinogenesis of chromate in the lung, we established a chromate-induced cancer model in the rat proximal airway and examined the relationship between chromium accumulations and the chromium-induced cancer and premalignant bronchial lesions of the rat.<br /><br /><strong>METHODS: </strong>Fifteen male, bred, 12-week-old Jcl-Wister rats were used. A pellet of strontium chromate were inserted into the bronchus of the rats. The rats were sacrificed 9 months after the pellet was inserted. We pathologically examined the region of the bronchi to which the pellet was attached. We quantified the amount of chromium accumulation in the bronchial lesions using a microscopic X-ray fluorescence analyzer.<br /><br /><strong>RESULTS: </strong>Of the 15 rats, 1 rat had a lesion of squamous cell carcinoma (SCC), 7 rats had carcinoma in situ (CIS) or dysplasia, 8 rats had squamous metaplasia, and 5 rats had goblet cell hyperplasia. The amounts of chromium accumulation in normal epithelium (n=24), goblet cell hyperplasia (n=14), squamous metaplasia (n=8), and dysplasia plus CIS plus SCC (n=9) were 500+/-1354, 713+/-1062, 941+/-1328, and 3511+/-4473 (mean+/-SD) counts/s/mA, respectively. The amount of chromium accumulation was significantly increased according to the progression of malignant change of the bronchial epithelium (Spearman's correlation coefficient by ranks, rs=0.454, P&lt;0.01).<br /><br /><strong>CONCLUSIONS: </strong>The amount of chromium accumulation was significantly increased according to the progression of malignant change of the bronchial epithelium. Examining the genetic alterations of histologic changes in this model was helpful in elucidating the process of carcinogenesis of chromium in the lung.","Microscopic analysis of the chromium content in the chromium-induced malignant and premalignant bronchial lesions of the rat Abs: <strong>OBJECTIVE: </strong>Our previous studies demonstrated that the frequency of gene instability in lung cancer of chromate workers was very high, but the frequencies of the p53 and ras gene mutations were low. To clarify the carcinogenesis of chromate in the lung, we established a chromate-induced cancer model in the rat proximal airway and examined the relationship between chromium accumulations and the chromium-induced cancer and premalignant bronchial lesions of the rat.<br /><br /><strong>METHODS: </strong>Fifteen male, bred, 12-week-old Jcl-Wister rats were used. A pellet of strontium chromate were inserted into the bronchus of the rats. The rats were sacrificed 9 months after the pellet was inserted. We pathologically examined the region of the bronchi to which the pellet was attached. We quantified the amount of chromium accumulation in the bronchial lesions using a microscopic X-ray fluorescence analyzer.<br /><br /><strong>RESULTS: </strong>Of the 15 rats, 1 rat had a lesion of squamous cell carcinoma (SCC), 7 rats had carcinoma in situ (CIS) or dysplasia, 8 rats had squamous metaplasia, and 5 rats had goblet cell hyperplasia. The amounts of chromium accumulation in normal epithelium (n=24), goblet cell hyperplasia (n=14), squamous metaplasia (n=8), and dysplasia plus CIS plus SCC (n=9) were 500+/-1354, 713+/-1062, 941+/-1328, and 3511+/-4473 (mean+/-SD) counts/s/mA, respectively. The amount of chromium accumulation was significantly increased according to the progression of malignant change of the bronchial epithelium (Spearman's correlation coefficient by ranks, rs=0.454, P&lt;0.01).<br /><br /><strong>CONCLUSIONS: </strong>The amount of chromium accumulation was significantly increased according to the progression of malignant change of the bronchial epithelium. Examining the genetic alterations of histologic changes in this model was helpful in elucidating the process of carcinogenesis of chromium in the lung."
1235454,Campos et al. 2005,Chromate reduction by Serratia marcescens isolated from tannery effluent,,Chromate reduction by Serratia marcescens isolated from tannery effluent Abs: 
1235452,Ginder-Vogel et al. 2005,Chromate reduction and retention processes within arid subsurface environments,"Chromate is a widespread contaminantthat has deleterious impacts on human health, the mobility and toxicity of which are diminished by reduction to Cr(III). While biological and chemical reduction reactions of Cr(VI) are well resolved, reduction within natural sediments, particularly of arid environments, remains poorly described. Here, we examine chromate reduction within arid sediments from the Hanford, WA site, where Fe(III) (hydr)oxide and carbonate coatings limit mineral reactivity. Chromium(VI) reduction by Hanford sediments is negligible unless pretreated with acid; acidic pretreatment of packed mineral beds having a Cr(VI) feed solution results in Cr(III) associating with the minerals antigorite and lizardite in addition to magnetite and Fe(II)-bearing clay minerals. Highly alkaline conditions (pH &gt; 14), representative of conditions near high-level nuclearwaste tanks, result in Fe(II) dissolution and concurrent Cr(VI) reduction. Additionally, Cr(III) and Cr(VI) are found associated with portlandite, suggesting a secondary mechanism for chromium retention at high pH. Thus, mineral reactivity is limited within this arid environment and appreciable reduction of Cr(VI) is restricted to highly alkaline conditions resulting near leaking radioactive waste disposal tanks.","Chromate reduction and retention processes within arid subsurface environments Abs: Chromate is a widespread contaminantthat has deleterious impacts on human health, the mobility and toxicity of which are diminished by reduction to Cr(III). While biological and chemical reduction reactions of Cr(VI) are well resolved, reduction within natural sediments, particularly of arid environments, remains poorly described. Here, we examine chromate reduction within arid sediments from the Hanford, WA site, where Fe(III) (hydr)oxide and carbonate coatings limit mineral reactivity. Chromium(VI) reduction by Hanford sediments is negligible unless pretreated with acid; acidic pretreatment of packed mineral beds having a Cr(VI) feed solution results in Cr(III) associating with the minerals antigorite and lizardite in addition to magnetite and Fe(II)-bearing clay minerals. Highly alkaline conditions (pH &gt; 14), representative of conditions near high-level nuclearwaste tanks, result in Fe(II) dissolution and concurrent Cr(VI) reduction. Additionally, Cr(III) and Cr(VI) are found associated with portlandite, suggesting a secondary mechanism for chromium retention at high pH. Thus, mineral reactivity is limited within this arid environment and appreciable reduction of Cr(VI) is restricted to highly alkaline conditions resulting near leaking radioactive waste disposal tanks."
1235451,Kim et al. 2006,Expression of yeast transcriptional activator MSN1 promotes accumulation of chromium and sulfur by enhancing sulfate transporter level in plants,"MSN1 is a putative yeast transcriptional activator involved in chromium (Cr) accumulation. Here we show that overexpression of MSN1 enhances Cr and sulfur accumulation and Cr tolerance in transgenic tobacco. In addition, we found that expression of NtST1 (Nicotiana tabacum sulfate transporter 1) was elevated in MSN1- expressing transgenic tobacco, suggesting that chromate and sulfate are taken up via the sulfate transporter in plants. Supporting this, expression of NtST1 increased levels of Cr and S in Saccharomyces cerevisiae. Our findings suggest that yeast transcriptional activators can be used for developing effective metal remediators, and for improving the nutritional status of plants.","Expression of yeast transcriptional activator MSN1 promotes accumulation of chromium and sulfur by enhancing sulfate transporter level in plants Abs: MSN1 is a putative yeast transcriptional activator involved in chromium (Cr) accumulation. Here we show that overexpression of MSN1 enhances Cr and sulfur accumulation and Cr tolerance in transgenic tobacco. In addition, we found that expression of NtST1 (Nicotiana tabacum sulfate transporter 1) was elevated in MSN1- expressing transgenic tobacco, suggesting that chromate and sulfate are taken up via the sulfate transporter in plants. Supporting this, expression of NtST1 increased levels of Cr and S in Saccharomyces cerevisiae. Our findings suggest that yeast transcriptional activators can be used for developing effective metal remediators, and for improving the nutritional status of plants."
1235445,Patel et al. 2006,Chromate allergy from contact with leather furnishings,,Chromate allergy from contact with leather furnishings Abs: 
1235442,Di et al. 2006,Surfactant-assisted synthesis and characterization of SrCrO4 nanostructures,"A simple and efficient microemulsion-based technique, which used the new Tx-100/cyclohexanol/ H2O system, was developed to synthesize SrCrO4 nanowire based nanostructures, including nanowire bundles and flower-like structures at different temperature. X-ray powder diffraction (XRD), field emission scanning electron microscope (FE-SEM), transmission electron microscopy (TEM) and high-resolution TEM (HRTEM) were used to characterize the products. Studies found that the reaction temperatures and the reaction systems have great influences on the final products. Optical properties studies by UV-Vis spectra and photoluminescence (PL) spectra confirmed that the as-obtained nanowires showed distinct optical activity under UV and visible light irradiation.","Surfactant-assisted synthesis and characterization of SrCrO4 nanostructures Abs: A simple and efficient microemulsion-based technique, which used the new Tx-100/cyclohexanol/ H2O system, was developed to synthesize SrCrO4 nanowire based nanostructures, including nanowire bundles and flower-like structures at different temperature. X-ray powder diffraction (XRD), field emission scanning electron microscope (FE-SEM), transmission electron microscopy (TEM) and high-resolution TEM (HRTEM) were used to characterize the products. Studies found that the reaction temperatures and the reaction systems have great influences on the final products. Optical properties studies by UV-Vis spectra and photoluminescence (PL) spectra confirmed that the as-obtained nanowires showed distinct optical activity under UV and visible light irradiation."
1235434,Quievryn et al. 2006,Lower mutagenicity but higher stability of Cr-DNA adducts formed during gradual chromate activation with ascorbate,"Recent epidemiological and risk assessment studies have found a very high risk of lung cancer among chromium(VI)-exposed workers even at permissible levels of exposure. However, mechanistic views on the key genotoxic role of transient Cr(V) intermediates were more consistent with the threshold or highly non-linear (heavy dose) models of genetic damage by intracellular Cr(VI). In this work, we examined the production of mutagenic DNA lesions during metabolism of Cr(VI) by its dominant reducer ascorbate (vitamin C) under conditions promoting increased yield of transient Cr forms. We found that slow reductive activation of Cr(VI) by limited concentrations of ascorbate resulted in a greater yield of DCFH-oxidizing Cr intermediates but these species were unable to cause DNA strand breaks. Cr(VI)-ascorbate reactions generated a high number of Cr-DNA adducts that were responsible for all mutagenic responses detected in Cr(VI)-treated pSP189 shuttle plasmids following their replication in human cells. Mutagenicity of DNA damage resulting from the reactions with increased stability of Cr intermediates was approximately four times lower relative to the conditions lacking detectable Cr(V) formation. Unlike other reactions, slow reduction of Cr(VI) with ascorbate produced Cr-DNA adducts that were more resistant to dissociation by chelators, suggesting multicoordinate binding of Cr(III) to DNA. Overall, our findings do not support the possibility that increased Cr(V) formation at depleted ascorbate levels modeling heavy dose exposures causes higher levels of mutagenic DNA damage.","Lower mutagenicity but higher stability of Cr-DNA adducts formed during gradual chromate activation with ascorbate Abs: Recent epidemiological and risk assessment studies have found a very high risk of lung cancer among chromium(VI)-exposed workers even at permissible levels of exposure. However, mechanistic views on the key genotoxic role of transient Cr(V) intermediates were more consistent with the threshold or highly non-linear (heavy dose) models of genetic damage by intracellular Cr(VI). In this work, we examined the production of mutagenic DNA lesions during metabolism of Cr(VI) by its dominant reducer ascorbate (vitamin C) under conditions promoting increased yield of transient Cr forms. We found that slow reductive activation of Cr(VI) by limited concentrations of ascorbate resulted in a greater yield of DCFH-oxidizing Cr intermediates but these species were unable to cause DNA strand breaks. Cr(VI)-ascorbate reactions generated a high number of Cr-DNA adducts that were responsible for all mutagenic responses detected in Cr(VI)-treated pSP189 shuttle plasmids following their replication in human cells. Mutagenicity of DNA damage resulting from the reactions with increased stability of Cr intermediates was approximately four times lower relative to the conditions lacking detectable Cr(V) formation. Unlike other reactions, slow reduction of Cr(VI) with ascorbate produced Cr-DNA adducts that were more resistant to dissociation by chelators, suggesting multicoordinate binding of Cr(III) to DNA. Overall, our findings do not support the possibility that increased Cr(V) formation at depleted ascorbate levels modeling heavy dose exposures causes higher levels of mutagenic DNA damage."
1235431,Messer et al. 2006,Causes of DNA single-strand breaks during reduction of chromate by glutathione in vitro and in cells,"Carcinogenic chromates induce DNA single-strand breaks (SSB) that are detectable by conventional alkali-based assays. However, the extent of direct breakage has been uncertain because excision repair and hydrolysis of Cr-DNA adducts at alkaline pH also generate SSB. We examined mechanisms of SSB production during chromate reduction by glutathione (GSH) and assessed the significance of these lesions in cells using genetic approaches. Cr(VI) reduction was biphasic and the formation of SSB occurred exclusively during the slow reaction phase. Catalase or iron chelators completely blocked DNA breakage, as did the use of GSH purified by a modified Chelex procedure. Thus, the direct intermediates of GSH-chromate reactions were unable to cause SSB unless activated by H2O2. SSB repair-deficient XRCC1(-/-) and proficient XRCC1+ EM9 cells had identical survival at doses causing up to 60% clonogenic death and accumulation of 1 mM Cr(VI). However, XRCC1(-/-) cells displayed higher lethality in the more toxic range and the depletion of GSH made them hypersensitive even to moderate doses. Elevation of cellular catalase or GSH levels eliminated survival differences between XRCC1(-/-) and XRCC1+ cells. In summary, formation of toxic SSB in cells occurs at relatively high chromate doses, requires H2O2, and is suppressed by high GSH concentrations.","Causes of DNA single-strand breaks during reduction of chromate by glutathione in vitro and in cells Abs: Carcinogenic chromates induce DNA single-strand breaks (SSB) that are detectable by conventional alkali-based assays. However, the extent of direct breakage has been uncertain because excision repair and hydrolysis of Cr-DNA adducts at alkaline pH also generate SSB. We examined mechanisms of SSB production during chromate reduction by glutathione (GSH) and assessed the significance of these lesions in cells using genetic approaches. Cr(VI) reduction was biphasic and the formation of SSB occurred exclusively during the slow reaction phase. Catalase or iron chelators completely blocked DNA breakage, as did the use of GSH purified by a modified Chelex procedure. Thus, the direct intermediates of GSH-chromate reactions were unable to cause SSB unless activated by H2O2. SSB repair-deficient XRCC1(-/-) and proficient XRCC1+ EM9 cells had identical survival at doses causing up to 60% clonogenic death and accumulation of 1 mM Cr(VI). However, XRCC1(-/-) cells displayed higher lethality in the more toxic range and the depletion of GSH made them hypersensitive even to moderate doses. Elevation of cellular catalase or GSH levels eliminated survival differences between XRCC1(-/-) and XRCC1+ cells. In summary, formation of toxic SSB in cells occurs at relatively high chromate doses, requires H2O2, and is suppressed by high GSH concentrations."
1235425,Smart et al. 2006,Activity of OGG1 variants in the repair of pro-oxidant-induced 8-oxo-2'-deoxyguanosine,"Cells are continuously exposed to damaging reactive oxygen species (ROS), which are produced from both endogenous and exogenous sources. 8-Oxodeoxyguanosine (8-oxodG) is an abundant base lesion formed during oxidative stress which, if not repaired, can give rise to G:C--&gt;T:A transversions in DNA. The 8-oxoguanine DNA glycosylase-1 (OGG1)-initiated base excision repair (BER) pathway operates to remove 8-oxodG lesions. Ogg1 deletion and polymorphism may result in a hypermutator phenotype and susceptibility to oxidative pathologies including cancer. Limited and conflicting evidence exists regarding the repair capacity of a prevalent human OGG1 (hOGG1) polymorphism, the Cys326-hOGG1 variant. The formamidopyrimidine DNA glycosylase (FPG)-modified comet assay was used to investigate the ability of sodium dichromate, potassium bromate and Ro19-8022 (+light) to induce DNA damage in mogg1(-/-) null (KO) and wild-type (WT) mouse embryonic fibroblasts (MEFs) and to assess hOGG1 variant-initiated BER capacities under conditions of oxidative stress. Treatment of WT MEFs with these pro-oxidant agents induced direct DNA strand breaks in a concentration-dependent manner, whereas, identical treatment of KO MEFs produced no effect. In contrast, KO MEFs accumulated significantly more FPG-sensitive sites than WT MEFs. Expression of hOGG1 in KO MEFs restored the WT phenotype in response to all pro-oxidants tested. The results suggest OGG1-initiated BER generates direct DNA strand breaks detected by the conventional comet assay, thus it is important that researchers do not interpret these as direct damage per se but rather a reflection of the repair process. The data also indicate Cys326-hOGG1-initiated BER is transiently impaired with respect to Ser326-hOGG1 (wild-type)- and Gly326-hOGG1 (artificial)-initiated BER following pro-oxidant treatment, possibly via hOGG1 cysteine 326 oxidation. This finding suggests the homozygous cys326/cys326 genotype may be classified as a biomarker of disease susceptibility, which is in support of a growing body of epidemiological evidence.","Activity of OGG1 variants in the repair of pro-oxidant-induced 8-oxo-2'-deoxyguanosine Abs: Cells are continuously exposed to damaging reactive oxygen species (ROS), which are produced from both endogenous and exogenous sources. 8-Oxodeoxyguanosine (8-oxodG) is an abundant base lesion formed during oxidative stress which, if not repaired, can give rise to G:C--&gt;T:A transversions in DNA. The 8-oxoguanine DNA glycosylase-1 (OGG1)-initiated base excision repair (BER) pathway operates to remove 8-oxodG lesions. Ogg1 deletion and polymorphism may result in a hypermutator phenotype and susceptibility to oxidative pathologies including cancer. Limited and conflicting evidence exists regarding the repair capacity of a prevalent human OGG1 (hOGG1) polymorphism, the Cys326-hOGG1 variant. The formamidopyrimidine DNA glycosylase (FPG)-modified comet assay was used to investigate the ability of sodium dichromate, potassium bromate and Ro19-8022 (+light) to induce DNA damage in mogg1(-/-) null (KO) and wild-type (WT) mouse embryonic fibroblasts (MEFs) and to assess hOGG1 variant-initiated BER capacities under conditions of oxidative stress. Treatment of WT MEFs with these pro-oxidant agents induced direct DNA strand breaks in a concentration-dependent manner, whereas, identical treatment of KO MEFs produced no effect. In contrast, KO MEFs accumulated significantly more FPG-sensitive sites than WT MEFs. Expression of hOGG1 in KO MEFs restored the WT phenotype in response to all pro-oxidants tested. The results suggest OGG1-initiated BER generates direct DNA strand breaks detected by the conventional comet assay, thus it is important that researchers do not interpret these as direct damage per se but rather a reflection of the repair process. The data also indicate Cys326-hOGG1-initiated BER is transiently impaired with respect to Ser326-hOGG1 (wild-type)- and Gly326-hOGG1 (artificial)-initiated BER following pro-oxidant treatment, possibly via hOGG1 cysteine 326 oxidation. This finding suggests the homozygous cys326/cys326 genotype may be classified as a biomarker of disease susceptibility, which is in support of a growing body of epidemiological evidence."
1235422,Chourey et al. 2006,Global molecular and morphological effects of 24-hour chromium(VI) exposure on Shewanella oneidensis MR-1,"The biological impact of 24-h (&quot;chronic&quot;) chromium(VI) [Cr(VI) or chromate] exposure on Shewanella oneidensis MR-1 was assessed by analyzing cellular morphology as well as genome-wide differential gene and protein expression profiles. Cells challenged aerobically with an initial chromate concentration of 0.3 mM in complex growth medium were compared to untreated control cells grown in the absence of chromate. At the 24-h time point at which cells were harvested for transcriptome and proteome analyses, no residual Cr(VI) was detected in the culture supernatant, thus suggesting the complete uptake and/or reduction of this metal by cells. In contrast to the untreated control cells, Cr(VI)-exposed cells formed apparently aseptate, nonmotile filaments that tended to aggregate. Transcriptome profiling and mass spectrometry-based proteomic characterization revealed that the principal molecular response to 24-h Cr(VI) exposure was the induction of prophage-related genes and their encoded products as well as a number of functionally undefined hypothetical genes that were located within the integrated phage regions of the MR-1 genome. In addition, genes with annotated functions in DNA metabolism, cell division, biosynthesis and degradation of the murein (peptidoglycan) sacculus, membrane response, and general environmental stress protection were upregulated, while genes encoding chemotaxis, motility, and transport/binding proteins were largely repressed under conditions of 24-h chromate treatment.","Global molecular and morphological effects of 24-hour chromium(VI) exposure on Shewanella oneidensis MR-1 Abs: The biological impact of 24-h (&quot;chronic&quot;) chromium(VI) [Cr(VI) or chromate] exposure on Shewanella oneidensis MR-1 was assessed by analyzing cellular morphology as well as genome-wide differential gene and protein expression profiles. Cells challenged aerobically with an initial chromate concentration of 0.3 mM in complex growth medium were compared to untreated control cells grown in the absence of chromate. At the 24-h time point at which cells were harvested for transcriptome and proteome analyses, no residual Cr(VI) was detected in the culture supernatant, thus suggesting the complete uptake and/or reduction of this metal by cells. In contrast to the untreated control cells, Cr(VI)-exposed cells formed apparently aseptate, nonmotile filaments that tended to aggregate. Transcriptome profiling and mass spectrometry-based proteomic characterization revealed that the principal molecular response to 24-h Cr(VI) exposure was the induction of prophage-related genes and their encoded products as well as a number of functionally undefined hypothetical genes that were located within the integrated phage regions of the MR-1 genome. In addition, genes with annotated functions in DNA metabolism, cell division, biosynthesis and degradation of the murein (peptidoglycan) sacculus, membrane response, and general environmental stress protection were upregulated, while genes encoding chemotaxis, motility, and transport/binding proteins were largely repressed under conditions of 24-h chromate treatment."
1235420,Azad et al. 2006,S-nitrosylation of Bcl-2 inhibits its ubiquitin-proteasomal degradation. A novel antiapoptotic mechanism that suppresses apoptosis,"Bcl-2 is a key apoptosis regulatory protein of the mitochondrial death pathway whose function is dependent on its expression levels. Although Bcl-2 expression is controlled by various mechanisms, post-translational modifications, such as ubiquitination and proteasomal degradation, have emerged as important regulators of Bcl-2 function. However, the underlying mechanisms of this regulation are unclear. We report here that Bcl-2 undergoes S-nitrosylation by endogenous nitric oxide (NO) in response to multiple apoptotic mediators and that this modification inhibits ubiquitin-proteasomal degradation of Bcl-2. Inhibition of NO production by the NO scavenger 2-(4-carboxyphenyl)-4,4,5,5-tetramethylimidazoline-1-oxyl-3-oxide and by NO synthase inhibitor aminoguanidine effectively inhibited S-nitrosylation of Bcl-2, increased its ubiquitination, and promoted apoptotic cell death induced by chromium (VI). In contrast, the NO donors dipropylenetriamine NONOate and sodium nitroprusside showed opposite effects. The effect of NO on Bcl-2 stability was shown to be independent of its dephosphorylation. Mutational analysis of Bcl-2 further showed that the two cysteine residues of Bcl-2 (Cys158 and Cys229) are important in the S-nitrosylation process and that mutations of these cysteines completely inhibited Bcl-2 S-nitrosylation. Treatment of the cells with other stress inducers, including Fas ligand and buthionine sulfoxide, also induced Bcl-2 S-nitrosylation, suggesting that this is a general phenomenon that regulates Bcl-2 stability and function under various stress conditions. These findings indicate a novel function of NO and its regulation of Bcl-2, which provides a key mechanism for the control of apoptotic cell death and cancer development.","S-nitrosylation of Bcl-2 inhibits its ubiquitin-proteasomal degradation. A novel antiapoptotic mechanism that suppresses apoptosis Abs: Bcl-2 is a key apoptosis regulatory protein of the mitochondrial death pathway whose function is dependent on its expression levels. Although Bcl-2 expression is controlled by various mechanisms, post-translational modifications, such as ubiquitination and proteasomal degradation, have emerged as important regulators of Bcl-2 function. However, the underlying mechanisms of this regulation are unclear. We report here that Bcl-2 undergoes S-nitrosylation by endogenous nitric oxide (NO) in response to multiple apoptotic mediators and that this modification inhibits ubiquitin-proteasomal degradation of Bcl-2. Inhibition of NO production by the NO scavenger 2-(4-carboxyphenyl)-4,4,5,5-tetramethylimidazoline-1-oxyl-3-oxide and by NO synthase inhibitor aminoguanidine effectively inhibited S-nitrosylation of Bcl-2, increased its ubiquitination, and promoted apoptotic cell death induced by chromium (VI). In contrast, the NO donors dipropylenetriamine NONOate and sodium nitroprusside showed opposite effects. The effect of NO on Bcl-2 stability was shown to be independent of its dephosphorylation. Mutational analysis of Bcl-2 further showed that the two cysteine residues of Bcl-2 (Cys158 and Cys229) are important in the S-nitrosylation process and that mutations of these cysteines completely inhibited Bcl-2 S-nitrosylation. Treatment of the cells with other stress inducers, including Fas ligand and buthionine sulfoxide, also induced Bcl-2 S-nitrosylation, suggesting that this is a general phenomenon that regulates Bcl-2 stability and function under various stress conditions. These findings indicate a novel function of NO and its regulation of Bcl-2, which provides a key mechanism for the control of apoptotic cell death and cancer development."
1235418,Nivinskas et al. 2006,Prooxidant cytotoxicity of chromate in mammalian cells: the opposite roles of DT-diaphorase and glutathione reductase,"The geno- and cytotoxicity of chromate, an important environmental pollutant, is partly attributed to the flavoenzyme-catalyzed reduction with the concomitant formation of reactive oxygen species. The aim of this work was to characterize the role of NAD(P)H:quinone oxidoreductase (NQO1, DT-diaphorase, EC 1.6.99.2) and glutathione reductase (GR, EC 1.6.4.2) in the mammalian cell cytotoxicity of chromate, which was evidenced controversially so far. The chromate reductase activity of NQO1 was higher than that of GR, but lower than that of lipoamide dehydrogenase (EC 1.6.4.3), ferredoxin:NADP+ reductase (EC 1.18.1.2), and NADPH: cytochrome P-450 reductase (EC 1.6.2.4). The reduction of chromate by NQO1 was accompanied by the formation of reactive oxygen species. The concentration of chromate for 50% survival of bovine leukemia virus-transformed lamb kidney fibroblasts (line FLK) during a 24-h incubation was (22 +/- 4) microM. The cytotoxicity was partly prevented by desferrioxamine, the antioxidant N,N'-diphenyl-p-phenylene diamine and by an inhibitor of NQO1, dicumarol, and potentiated by 1,3-bis-(2-chloroethyl)-1-nitrosourea (BCNU), which inactivates GR. The NADPH-dependent chromate reduction by digitonin-permeabilized FLK cells was partly inhibited by dicumarol and not affected by BCNU. Taken together, these data indicate that the oxidative stress-type cytotoxicity of chromate in FLK cells may be partly attributed to its reduction by NQO1, but not by GR. The effect of BCNU on the chromate cytotoxicity may indicate that the general antioxidant action of reduced glutathione is more important than its prooxidant activities arising from the reactions with chromate.","Prooxidant cytotoxicity of chromate in mammalian cells: the opposite roles of DT-diaphorase and glutathione reductase Abs: The geno- and cytotoxicity of chromate, an important environmental pollutant, is partly attributed to the flavoenzyme-catalyzed reduction with the concomitant formation of reactive oxygen species. The aim of this work was to characterize the role of NAD(P)H:quinone oxidoreductase (NQO1, DT-diaphorase, EC 1.6.99.2) and glutathione reductase (GR, EC 1.6.4.2) in the mammalian cell cytotoxicity of chromate, which was evidenced controversially so far. The chromate reductase activity of NQO1 was higher than that of GR, but lower than that of lipoamide dehydrogenase (EC 1.6.4.3), ferredoxin:NADP+ reductase (EC 1.18.1.2), and NADPH: cytochrome P-450 reductase (EC 1.6.2.4). The reduction of chromate by NQO1 was accompanied by the formation of reactive oxygen species. The concentration of chromate for 50% survival of bovine leukemia virus-transformed lamb kidney fibroblasts (line FLK) during a 24-h incubation was (22 +/- 4) microM. The cytotoxicity was partly prevented by desferrioxamine, the antioxidant N,N'-diphenyl-p-phenylene diamine and by an inhibitor of NQO1, dicumarol, and potentiated by 1,3-bis-(2-chloroethyl)-1-nitrosourea (BCNU), which inactivates GR. The NADPH-dependent chromate reduction by digitonin-permeabilized FLK cells was partly inhibited by dicumarol and not affected by BCNU. Taken together, these data indicate that the oxidative stress-type cytotoxicity of chromate in FLK cells may be partly attributed to its reduction by NQO1, but not by GR. The effect of BCNU on the chromate cytotoxicity may indicate that the general antioxidant action of reduced glutathione is more important than its prooxidant activities arising from the reactions with chromate."
1235417,Buehrlen et al. 2007,Cumulative genotoxic and apoptotic effects of xenobiotics in a mini organ culture model of human nasal mucosa as detected by the alkaline single cell microgel electrophoresis assay and the annexin V-affinity assay,"Three-dimensional mini organ cultures of human inferior nasal turbinate epithelia have proved to be a useful tool in genotoxicology studies. They allow repetitive or chronic exposure of cells to xenobiotics in a well-preserved organ-specific mucosal architecture for an extended period of time. It is the aim of the present study to concurrently monitor cumulative genotoxic and apoptotic effects of sodium dichromate, N-nitrosodiethylamine (NDEA) and N-methyl-N-nitro-N-nitroso-guanidine (MNNG). Mini organs were raised by separating fresh specimens of human inferior nasal turbinates (n=11) into 1 mm3 sized pieces and culturing them on multiwell plates with bronchial epithelial basal medium for 6 days. Aliquots of the mini organs were subsequently exposed to sodium dichromate (1.0 mM, 1h), NDEA (50 mM, 1h) or MNNG (0.07 mM, 1h) on days 7, 9 and 11 versus a single exposure on day 11 only. DNA fragmentation and apoptotic events were assessed on day 11 using the alkaline single cell microgel electrophoresis assay (comet assay) and the annexin V-affinity assay. Significant DNA fragmentation could be demonstrated after a single exposure of the mini organs to sodium dichromate. Following three subsequent incubations, there was a further increase in the genetic damage observed, accompanied by an increase in the rate of apoptotic cells. In contrast, after single and triple incubation with NDEA there was neither an increase in genetic damage nor in the fraction of apoptotic cells detectable. Repetitive exposure to MNNG resulted in an accumulation of DNA damage without an observable increase in apoptosis. The results verify the need to assess apoptosis in genotoxicology research and to investigate cumulative effects of xenobiotics. Three-dimensional mini organ cultures of human upper aerodigestive tract epithelia have shown to be well-suited for improving the ability to distinguish between cumulative genotoxic and apoptotic effects.","Cumulative genotoxic and apoptotic effects of xenobiotics in a mini organ culture model of human nasal mucosa as detected by the alkaline single cell microgel electrophoresis assay and the annexin V-affinity assay Abs: Three-dimensional mini organ cultures of human inferior nasal turbinate epithelia have proved to be a useful tool in genotoxicology studies. They allow repetitive or chronic exposure of cells to xenobiotics in a well-preserved organ-specific mucosal architecture for an extended period of time. It is the aim of the present study to concurrently monitor cumulative genotoxic and apoptotic effects of sodium dichromate, N-nitrosodiethylamine (NDEA) and N-methyl-N-nitro-N-nitroso-guanidine (MNNG). Mini organs were raised by separating fresh specimens of human inferior nasal turbinates (n=11) into 1 mm3 sized pieces and culturing them on multiwell plates with bronchial epithelial basal medium for 6 days. Aliquots of the mini organs were subsequently exposed to sodium dichromate (1.0 mM, 1h), NDEA (50 mM, 1h) or MNNG (0.07 mM, 1h) on days 7, 9 and 11 versus a single exposure on day 11 only. DNA fragmentation and apoptotic events were assessed on day 11 using the alkaline single cell microgel electrophoresis assay (comet assay) and the annexin V-affinity assay. Significant DNA fragmentation could be demonstrated after a single exposure of the mini organs to sodium dichromate. Following three subsequent incubations, there was a further increase in the genetic damage observed, accompanied by an increase in the rate of apoptotic cells. In contrast, after single and triple incubation with NDEA there was neither an increase in genetic damage nor in the fraction of apoptotic cells detectable. Repetitive exposure to MNNG resulted in an accumulation of DNA damage without an observable increase in apoptosis. The results verify the need to assess apoptosis in genotoxicology research and to investigate cumulative effects of xenobiotics. Three-dimensional mini organ cultures of human upper aerodigestive tract epithelia have shown to be well-suited for improving the ability to distinguish between cumulative genotoxic and apoptotic effects."
1235413,Emmanouil et al. 2007,Macromolecule oxidation and DNA repair in mussel (Mytilus edulis L.) gill following exposure to Cd and Cr(VI),"The oxidation of DNA and lipid was analysed in the marine mussel (Mytilus edulis) in response to exposure (10microg/l and 200microg/l) to cadmium (Cd) and chromium [Cr(VI)]. Concentration dependent uptake of both metals into mussel tissues was established and levels of gill ATP were not depleted at these exposure levels. DNA strand breakage in gill cells (analysed by the comet assay) was elevated by both metals, however, DNA oxidation [measured by DNA strand breakage induced by the DNA repair enzyme formamidopyrimidine glycosylase (FPG)] was not elevated. This was despite a statistically significant increase in both malondialdehyde and 4-hydroxynonenal - indicative of lipid peroxidation - following treatment with Cd. In contrast, both frank DNA stand breaks and FPG-induced DNA strand breaks (indicative of DNA oxidation) were increased following injection of mussels with sodium dichromate (10.4microgCr(VI)/mussel). The metals also showed differential inhibitory potential towards DNA repair enzyme activity with Cd exhibiting inhibition of DNA cutting activity towards an oligonucleotide containing 8-oxo-7,8-dihydro-2'-deoxyguanosine and Cr(VI) showing inhibition of such activity towards an oligonucleotide containing ethenoadenosine, both at 200microg/l. The metals thus show DNA damage activity in mussel gill with distinct mechanisms involving both direct and indirect (oxidative) DNA damage, as well as impairing different DNA repair capacities. A combination of these activities can contribute to adverse effects in these organisms.","Macromolecule oxidation and DNA repair in mussel (Mytilus edulis L.) gill following exposure to Cd and Cr(VI) Abs: The oxidation of DNA and lipid was analysed in the marine mussel (Mytilus edulis) in response to exposure (10microg/l and 200microg/l) to cadmium (Cd) and chromium [Cr(VI)]. Concentration dependent uptake of both metals into mussel tissues was established and levels of gill ATP were not depleted at these exposure levels. DNA strand breakage in gill cells (analysed by the comet assay) was elevated by both metals, however, DNA oxidation [measured by DNA strand breakage induced by the DNA repair enzyme formamidopyrimidine glycosylase (FPG)] was not elevated. This was despite a statistically significant increase in both malondialdehyde and 4-hydroxynonenal - indicative of lipid peroxidation - following treatment with Cd. In contrast, both frank DNA stand breaks and FPG-induced DNA strand breaks (indicative of DNA oxidation) were increased following injection of mussels with sodium dichromate (10.4microgCr(VI)/mussel). The metals also showed differential inhibitory potential towards DNA repair enzyme activity with Cd exhibiting inhibition of DNA cutting activity towards an oligonucleotide containing 8-oxo-7,8-dihydro-2'-deoxyguanosine and Cr(VI) showing inhibition of such activity towards an oligonucleotide containing ethenoadenosine, both at 200microg/l. The metals thus show DNA damage activity in mussel gill with distinct mechanisms involving both direct and indirect (oxidative) DNA damage, as well as impairing different DNA repair capacities. A combination of these activities can contribute to adverse effects in these organisms."
1235404,Gibbs-Davis et al. 2007,Anion chelation by amido acid functionalized fused quartz/water interfaces studied by nonlinear optics,"We report resonantly enhanced surface second harmonic generation (SHG) measurements to track the interaction of the EPA priority toxic metal pollutant chromium(VI) with fused quartz/water interfaces containing tailor-made amino acids that serve as model systems for environmental and biological interfaces. chi3 measurements of amido acid functionalized fused quartz/water interfaces are consistent with two acid-base equilibria, suggesting the formation of a laterally hydrogen-bonded environment similar to what is observed for aliphatic carboxylic acids. Chromate adsorption isotherms recorded at pH 7 are suggestive of an intramolecular chelation mechanism that becomes important when four or more hydrogen-bonding moieties are displayed toward the incoming chromate. The strong binding affinities of the amido acid functionalized fused quartz/water interfaces toward chromate are consistent with nearly 50% slower transport rates with respect to free-flowing groundwater, indicating that, in the absence of redox processes, peptide materials in heterogeneous geochemical environments can significantly increase chromate residence times. The strong evidence for synergistic effects dominating the interactions of chromate with surface-bound amido acids indicates that chemical complexity can be systematically addressed using tailor-made organic surfaces and interfaces.","Anion chelation by amido acid functionalized fused quartz/water interfaces studied by nonlinear optics Abs: We report resonantly enhanced surface second harmonic generation (SHG) measurements to track the interaction of the EPA priority toxic metal pollutant chromium(VI) with fused quartz/water interfaces containing tailor-made amino acids that serve as model systems for environmental and biological interfaces. chi3 measurements of amido acid functionalized fused quartz/water interfaces are consistent with two acid-base equilibria, suggesting the formation of a laterally hydrogen-bonded environment similar to what is observed for aliphatic carboxylic acids. Chromate adsorption isotherms recorded at pH 7 are suggestive of an intramolecular chelation mechanism that becomes important when four or more hydrogen-bonding moieties are displayed toward the incoming chromate. The strong binding affinities of the amido acid functionalized fused quartz/water interfaces toward chromate are consistent with nearly 50% slower transport rates with respect to free-flowing groundwater, indicating that, in the absence of redox processes, peptide materials in heterogeneous geochemical environments can significantly increase chromate residence times. The strong evidence for synergistic effects dominating the interactions of chromate with surface-bound amido acids indicates that chemical complexity can be systematically addressed using tailor-made organic surfaces and interfaces."
1235403,Hininger et al. 2007,Safety of trivalent chromium complexes: no evidence for DNA damage in human HaCaT keratinocytes,"Several studies have demonstrated beneficial effects of supplemental trivalent Cr in subjects with reduced insulin sensitivity with no documented signs of toxicity. However, recent studies have questioned the safety of supplemental trivalent Cr complexes. The objective of this study was to evaluate the cytotoxic and genotoxic potential of the Cr(III) complexes (histidinate, picolinate, and chloride) used as nutrient supplements compared with Cr(VI) dichromate. The cytotoxic and genotoxic effects of the Cr complexes were assessed in human HaCaT keratinocytes. The concentrations of Cr required to decrease cell viability were assessed by determining the ability of a keratinocyte cell line (HaCaT) to reduce tetrazolium dye, 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide. DNA damage using the Comet assay and the production of 8-hydroxy-2'-deoxyguanosine were also determined with and without hydrogen peroxide-induced stress. The LC50 for human cultured HaCaT keratinocytes was 50 microM for hexavalent sodium dichromate and more than 120-fold higher for Cr chloride (6 mM) and Cr histidinate (10 mM). For Cr picolinate at saturating concentration (120 microM) the LC50 was not attained. High Cr(III) concentrations, 250 microM Cr as Cr chloride and Cr histidinate and 120 microM Cr picolinate (highest amount soluble in the system), not only did not result in oxidative DNA damage but exhibited protective antioxidant effects when cells were exposed to hydrogen peroxide-induced oxidative stress. These data further support the low toxicity of trivalent Cr complexes used in nutrient supplements.","Safety of trivalent chromium complexes: no evidence for DNA damage in human HaCaT keratinocytes Abs: Several studies have demonstrated beneficial effects of supplemental trivalent Cr in subjects with reduced insulin sensitivity with no documented signs of toxicity. However, recent studies have questioned the safety of supplemental trivalent Cr complexes. The objective of this study was to evaluate the cytotoxic and genotoxic potential of the Cr(III) complexes (histidinate, picolinate, and chloride) used as nutrient supplements compared with Cr(VI) dichromate. The cytotoxic and genotoxic effects of the Cr complexes were assessed in human HaCaT keratinocytes. The concentrations of Cr required to decrease cell viability were assessed by determining the ability of a keratinocyte cell line (HaCaT) to reduce tetrazolium dye, 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide. DNA damage using the Comet assay and the production of 8-hydroxy-2'-deoxyguanosine were also determined with and without hydrogen peroxide-induced stress. The LC50 for human cultured HaCaT keratinocytes was 50 microM for hexavalent sodium dichromate and more than 120-fold higher for Cr chloride (6 mM) and Cr histidinate (10 mM). For Cr picolinate at saturating concentration (120 microM) the LC50 was not attained. High Cr(III) concentrations, 250 microM Cr as Cr chloride and Cr histidinate and 120 microM Cr picolinate (highest amount soluble in the system), not only did not result in oxidative DNA damage but exhibited protective antioxidant effects when cells were exposed to hydrogen peroxide-induced oxidative stress. These data further support the low toxicity of trivalent Cr complexes used in nutrient supplements."
1235401,Tokunaga et al. 2007,Long-term stability of organic carbon-stimulated chromate reduction in contaminated soils and its relation to manganese redox status,"In situ reduction of toxic Cr(VI) to less hazardous Cr(III) is becoming a popular strategy for remediating contaminated soils. However, the long-term stability of reduced Cr remains to be understood, especially given the common presence of Mn(III, IV) oxides that re-oxidize Cr(III). This 4.6 year laboratory study tracked Cr and Mn redox transformations in soils contaminated with Cr(VI), which were then treated with different amounts of organic carbon (OC). Changes in Cr and Mn oxidation states within soils were directly and nondestructively measured using micro-X-ray absorption near-edge structure spectroscopy. Chromate reduction was roughly first-order, and the extent of reduction was enhanced with higher OC additions. However, significant Cr(III) re-oxidation occurred in soils exposed to the highest Cr(VI) concentrations (2560 mg kg(-1)). Transient Cr(Ill) re-oxidation up to 420 mg kg(-1) was measured at 1.1 years after OC treatment, followed by further reduction. Chromate concentrations increased by 220 mg kg(-1) at the end of the study (4.6 years) in one soil. The causal role that the Mn oxidation state had in re-oxidizing Cr was supported by trends in Mn K-edge energies. These results provide strong evidence for long-term dependence of soil Cr oxidation states on balances between OC availability and Mn redox status.","Long-term stability of organic carbon-stimulated chromate reduction in contaminated soils and its relation to manganese redox status Abs: In situ reduction of toxic Cr(VI) to less hazardous Cr(III) is becoming a popular strategy for remediating contaminated soils. However, the long-term stability of reduced Cr remains to be understood, especially given the common presence of Mn(III, IV) oxides that re-oxidize Cr(III). This 4.6 year laboratory study tracked Cr and Mn redox transformations in soils contaminated with Cr(VI), which were then treated with different amounts of organic carbon (OC). Changes in Cr and Mn oxidation states within soils were directly and nondestructively measured using micro-X-ray absorption near-edge structure spectroscopy. Chromate reduction was roughly first-order, and the extent of reduction was enhanced with higher OC additions. However, significant Cr(III) re-oxidation occurred in soils exposed to the highest Cr(VI) concentrations (2560 mg kg(-1)). Transient Cr(Ill) re-oxidation up to 420 mg kg(-1) was measured at 1.1 years after OC treatment, followed by further reduction. Chromate concentrations increased by 220 mg kg(-1) at the end of the study (4.6 years) in one soil. The causal role that the Mn oxidation state had in re-oxidizing Cr was supported by trends in Mn K-edge energies. These results provide strong evidence for long-term dependence of soil Cr oxidation states on balances between OC availability and Mn redox status."
1235400,Hoffmann et al. 2007,Thermal treatment of harzardous waste for heavy metal recovery,"In this study, a new method for recovering heavy metals from hazardous waste is introduced. The process is characterized by a separation of heavy metals and residues during the thermal treatment under a sub-stoichiometric atmosphere in a rotary kiln. After leaving the rotary kiln the separated heavy metals are precipitated in a hot gas ceramic filter. Using this technology, hazardous materials, both liquids and pasty hazardous waste containing heavy metals, can be treated and a product with a quasi-raw material condition can be formed. In contrast to current methods,the harmful substances should not be immobilized and disposed. In fact, a saleable product highly concentrated with heavy metals should be formed. During preliminary investigations with a solution containing sodium chromate tetrahydrate, the process was tested in a pilot plant. Here,the separation of chromium could be demonstrated with leaching tests and characterization of the filter dust. Analysis concerning the disposability of the residues had not been carried out because only the process and the characteristic of the filter dust were in the centre of attention.","Thermal treatment of harzardous waste for heavy metal recovery Abs: In this study, a new method for recovering heavy metals from hazardous waste is introduced. The process is characterized by a separation of heavy metals and residues during the thermal treatment under a sub-stoichiometric atmosphere in a rotary kiln. After leaving the rotary kiln the separated heavy metals are precipitated in a hot gas ceramic filter. Using this technology, hazardous materials, both liquids and pasty hazardous waste containing heavy metals, can be treated and a product with a quasi-raw material condition can be formed. In contrast to current methods,the harmful substances should not be immobilized and disposed. In fact, a saleable product highly concentrated with heavy metals should be formed. During preliminary investigations with a solution containing sodium chromate tetrahydrate, the process was tested in a pilot plant. Here,the separation of chromium could be demonstrated with leaching tests and characterization of the filter dust. Analysis concerning the disposability of the residues had not been carried out because only the process and the characteristic of the filter dust were in the centre of attention."
1235389,De Flora et al. 2008,Lack of genotoxic effects in hematopoietic and gastrointestinal cells of mice receiving chromium(VI) with the drinking water,"Chromium(VI) is genotoxic when tested in vitro or injected parenterally in such a way to escape detoxification mechanisms. However, its genotoxicity and potential carcinogenicity are lost, depending on dose and administration route, due to efficient reduction in body fluids and nontarget cells. Chromium(VI) is a Group 1 IARC carcinogen, but only in the respiratory tract and in well-defined occupational settings that involved heavy exposures. Recently, concern has been expressed that oral chromium(VI) may be a gastric carcinogen. We demonstrated that administration of very high doses of chromium(VI) with the drinking water does not induce any clastogenic effect in hematopoietic cells of adult mice and their fetuses. Thereafter, we investigated whether administration of chromium(VI) with the drinking water may induce local genotoxic effects in the gastrointestinal tract. Sodium dichromate dihydrate was administered to mice for 9 consecutive months, at doses corresponding to 5 and 20 mg chromium(VI)/l, which exceed drinking water standards by 100 and 400 times, respectively. Under these conditions, chromium(VI) failed to enhance the frequency of DNA-protein crosslinks and did not cause oxidative DNA damage, measured in terms of 8-oxo-2'-deoxyguanosine, in the forestomach, glandular stomach and duodenum. When cells from the same organs were isolated and challenged in vitro with chromium(VI), as positive controls, the same genotoxicity biomarkers were evidently affected. Thus, consistently with the knowledge accumulated in 50 years of research on chromium(VI) kinetics and metabolism, oral chromium(VI) appears to be devoid of genotoxicity in the gastrointestinal tract. After 9 months, we did not observe any variation of tumor yield in skin, lung, forestomach, glandular stomach, and duodenum of chromium(VI)-treated mice. These results are discussed in the light of literature data, also including a recent 2-year carcinogenicity study performed by the National Toxicology Program.","Lack of genotoxic effects in hematopoietic and gastrointestinal cells of mice receiving chromium(VI) with the drinking water Abs: Chromium(VI) is genotoxic when tested in vitro or injected parenterally in such a way to escape detoxification mechanisms. However, its genotoxicity and potential carcinogenicity are lost, depending on dose and administration route, due to efficient reduction in body fluids and nontarget cells. Chromium(VI) is a Group 1 IARC carcinogen, but only in the respiratory tract and in well-defined occupational settings that involved heavy exposures. Recently, concern has been expressed that oral chromium(VI) may be a gastric carcinogen. We demonstrated that administration of very high doses of chromium(VI) with the drinking water does not induce any clastogenic effect in hematopoietic cells of adult mice and their fetuses. Thereafter, we investigated whether administration of chromium(VI) with the drinking water may induce local genotoxic effects in the gastrointestinal tract. Sodium dichromate dihydrate was administered to mice for 9 consecutive months, at doses corresponding to 5 and 20 mg chromium(VI)/l, which exceed drinking water standards by 100 and 400 times, respectively. Under these conditions, chromium(VI) failed to enhance the frequency of DNA-protein crosslinks and did not cause oxidative DNA damage, measured in terms of 8-oxo-2'-deoxyguanosine, in the forestomach, glandular stomach and duodenum. When cells from the same organs were isolated and challenged in vitro with chromium(VI), as positive controls, the same genotoxicity biomarkers were evidently affected. Thus, consistently with the knowledge accumulated in 50 years of research on chromium(VI) kinetics and metabolism, oral chromium(VI) appears to be devoid of genotoxicity in the gastrointestinal tract. After 9 months, we did not observe any variation of tumor yield in skin, lung, forestomach, glandular stomach, and duodenum of chromium(VI)-treated mice. These results are discussed in the light of literature data, also including a recent 2-year carcinogenicity study performed by the National Toxicology Program."
1235382,Hantson et al. 2008,"Kinetics and determinants of the changes of CC16, a lung secretory protein in a rat model of toxic lung injury","<strong>PURPOSE: </strong>To investigate the kinetics and the determinants of the changes of the Clara cell 16 kDa protein (CC16) as a marker of lung injury following exposure to different toxicants.<br /><br /><strong>METHODS: </strong>Rats were treated with 4-Ipomeanol (IPO), alpha-naphtylthiourea (ANTU), sodium chromate (Na(2)CrO(4)) or paraquat-(PQ). The changes of CC16, total protein, albumin, and cystatin-C were determined on BALF supernatan, and CC16, cystatin-C and creatinine levels were also determined in serum.<br /><br /><strong>RESULTS: </strong>Bronchiolar insult due to IPO or ANTU resulted in an initial transient increase of serum CC16, parallel to that of albumin in BALF, and a subsequent reduction in both BALF and serum. A slight reduction of CC16 in BALF was already apparent one hour following treatment with PQ. In the serum, CC16 increased to 400% of basal value. With PQ and Na(2)CrO(4), the elevation of CC16 was mainly determined by the degree of renal impairment.","Kinetics and determinants of the changes of CC16, a lung secretory protein in a rat model of toxic lung injury Abs: <strong>PURPOSE: </strong>To investigate the kinetics and the determinants of the changes of the Clara cell 16 kDa protein (CC16) as a marker of lung injury following exposure to different toxicants.<br /><br /><strong>METHODS: </strong>Rats were treated with 4-Ipomeanol (IPO), alpha-naphtylthiourea (ANTU), sodium chromate (Na(2)CrO(4)) or paraquat-(PQ). The changes of CC16, total protein, albumin, and cystatin-C were determined on BALF supernatan, and CC16, cystatin-C and creatinine levels were also determined in serum.<br /><br /><strong>RESULTS: </strong>Bronchiolar insult due to IPO or ANTU resulted in an initial transient increase of serum CC16, parallel to that of albumin in BALF, and a subsequent reduction in both BALF and serum. A slight reduction of CC16 in BALF was already apparent one hour following treatment with PQ. In the serum, CC16 increased to 400% of basal value. With PQ and Na(2)CrO(4), the elevation of CC16 was mainly determined by the degree of renal impairment."
1235376,Bingol et al. 2009,Biosorption of chromate anions from aqueous solution by a cationic surfactant-modified lichen (Cladonia rangiformis (L.)),"Biosorption has been appearing as a useful alternative to conventional treatment systems for the removal of toxic metals from aqueous stream. The batch removal of chromate anions (CrO(4)(2-)) from wastewater under different experimental conditions using a cationic surfactant-modified lichen (Cladonia rangiformis (L.)) was investigated in this study. Cetyl trimethyl ammonium bromide (CTAB) was used for biomass modification. The results of the experiments showed that biomass modification substantially improved the biosorption efficiency. Effects of pH, biosorption time, initial CrO(4)(2-) concentration, biosorbent dosage, and the existence of the surfactant on the biosorption of CrO(4)(2-) anions were studied. Studies up to date have shown that the biosorption efficiency of chromium increased as the pH of the solution decreased. In the present study, the removal of chromate anions from aqueous solutions at high pH values with surfactant-modified lichen was investigated. From the results of the experiments it was seen that the removal of chromate anions by modified lichen was 61% at the solution natural pH (pH 5.11) but at the same pH value the removal of chromate anions by unmodified lichen was 6%. Also concentrations ranging from 30 to 150 mg/L Cr(IV) were tested and the biosorptive removal efficiency of the metal ions from aqueous solution at high pH was achieved more than 98%.","Biosorption of chromate anions from aqueous solution by a cationic surfactant-modified lichen (Cladonia rangiformis (L.)) Abs: Biosorption has been appearing as a useful alternative to conventional treatment systems for the removal of toxic metals from aqueous stream. The batch removal of chromate anions (CrO(4)(2-)) from wastewater under different experimental conditions using a cationic surfactant-modified lichen (Cladonia rangiformis (L.)) was investigated in this study. Cetyl trimethyl ammonium bromide (CTAB) was used for biomass modification. The results of the experiments showed that biomass modification substantially improved the biosorption efficiency. Effects of pH, biosorption time, initial CrO(4)(2-) concentration, biosorbent dosage, and the existence of the surfactant on the biosorption of CrO(4)(2-) anions were studied. Studies up to date have shown that the biosorption efficiency of chromium increased as the pH of the solution decreased. In the present study, the removal of chromate anions from aqueous solutions at high pH values with surfactant-modified lichen was investigated. From the results of the experiments it was seen that the removal of chromate anions by modified lichen was 61% at the solution natural pH (pH 5.11) but at the same pH value the removal of chromate anions by unmodified lichen was 6%. Also concentrations ranging from 30 to 150 mg/L Cr(IV) were tested and the biosorptive removal efficiency of the metal ions from aqueous solution at high pH was achieved more than 98%."
1235374,Villegas et al. 2008,Chromate removal by yeasts isolated from sediments of a tanning factory and a mine site in Argentina,"Twenty-one yeast-like microorganisms were isolated from tannery effluents and from a nickel-copper mine in Argentina. They were tested for their Cu(II), Ni(II), Cd(II) and Cr(VI) tolerance in qualitative assays on solid medium. Three isolates were selected for their multiple tolerance to the different heavy metals and highest tolerance to Cr(VI). According to morphological and physiological analysis and 26S rDNA D1/D2 domain sequences the isolates were characterized as: Lecythophora sp. NGV-1, Candida sp. NGV-9 and Aureobasidium pullulans VR-8. Resistance of the three strains to high Cr(VI) concentrations and their ability to remove Cr(VI) were assessed using YNB-glucose medium supplemented with 0.5 and 1 mM Cr(VI). Chromate removal activity was estimated by measuring remaining Cr(VI) concentration in the supernatant using the colorimetric 1,5-diphenylcarbazide method and total chromium was determined by flame atomic absorption spectroscopy. The results indicate that the initial Cr(VI) concentration negatively influenced growth and the specific growth rate but stimulated the metabolic activity of the three strains; resistance to Cr(VI) by these strains was mainly due to reduction of Cr(VI) rather than chromium bioaccumulation. This study showed the potential ability of these strains as tools for bioremediation of Cr(VI) from contaminated sites.","Chromate removal by yeasts isolated from sediments of a tanning factory and a mine site in Argentina Abs: Twenty-one yeast-like microorganisms were isolated from tannery effluents and from a nickel-copper mine in Argentina. They were tested for their Cu(II), Ni(II), Cd(II) and Cr(VI) tolerance in qualitative assays on solid medium. Three isolates were selected for their multiple tolerance to the different heavy metals and highest tolerance to Cr(VI). According to morphological and physiological analysis and 26S rDNA D1/D2 domain sequences the isolates were characterized as: Lecythophora sp. NGV-1, Candida sp. NGV-9 and Aureobasidium pullulans VR-8. Resistance of the three strains to high Cr(VI) concentrations and their ability to remove Cr(VI) were assessed using YNB-glucose medium supplemented with 0.5 and 1 mM Cr(VI). Chromate removal activity was estimated by measuring remaining Cr(VI) concentration in the supernatant using the colorimetric 1,5-diphenylcarbazide method and total chromium was determined by flame atomic absorption spectroscopy. The results indicate that the initial Cr(VI) concentration negatively influenced growth and the specific growth rate but stimulated the metabolic activity of the three strains; resistance to Cr(VI) by these strains was mainly due to reduction of Cr(VI) rather than chromium bioaccumulation. This study showed the potential ability of these strains as tools for bioremediation of Cr(VI) from contaminated sites."
1235371,De Gioannis et al. 2008,Chromate adsorption in a transformed red mud permeable reactive barrier using electrokinesis,"Electrokinetic removal of chromium from artificially contaminated clayey soil in a bench-scale cell was enhanced by a reactive barrier (RB) of transformed Red Mud (TRM, BAUXSOL) fitted near the anode. When using 0.75 wt% of TRM in a soil spiked up to a Cr (VI) concentration of 1000 mg/kg dry weight, about 54 wt% of total Cr was removed after 6 days, as compared to only 36 wt% from the control cell without TRM RB. Increasing the duration of the treatment up to 12 days and using 1.5 wt% of TRM resulted in the increase of the above mentioned removal efficiencies up to 93 wt% and 57 wt%, respectively. The reduction of Cr (VI) into less mobile Cr (III) was limited by the TRM RB; in fact, lower reduction percentages for the tests with TRM RB as compared to the tests without were observed (respectively, 42% versus 72% for 6 days test, and 60% versus 93% for 12 days test). The obtained results show that Cr (VI) removal efficiency is proportional to the duration of the treatment and enhanced by the development of favorable pH conditions caused by the activity of the anodic TRM RB. It is suggested that electrokinesis may increase the efficiency of metal-oxyanion adsorption on TRM, as well as that the use of a TRM RB may improve the efficiency of contaminated soil remediation by means of electrokinesis.","Chromate adsorption in a transformed red mud permeable reactive barrier using electrokinesis Abs: Electrokinetic removal of chromium from artificially contaminated clayey soil in a bench-scale cell was enhanced by a reactive barrier (RB) of transformed Red Mud (TRM, BAUXSOL) fitted near the anode. When using 0.75 wt% of TRM in a soil spiked up to a Cr (VI) concentration of 1000 mg/kg dry weight, about 54 wt% of total Cr was removed after 6 days, as compared to only 36 wt% from the control cell without TRM RB. Increasing the duration of the treatment up to 12 days and using 1.5 wt% of TRM resulted in the increase of the above mentioned removal efficiencies up to 93 wt% and 57 wt%, respectively. The reduction of Cr (VI) into less mobile Cr (III) was limited by the TRM RB; in fact, lower reduction percentages for the tests with TRM RB as compared to the tests without were observed (respectively, 42% versus 72% for 6 days test, and 60% versus 93% for 12 days test). The obtained results show that Cr (VI) removal efficiency is proportional to the duration of the treatment and enhanced by the development of favorable pH conditions caused by the activity of the anodic TRM RB. It is suggested that electrokinesis may increase the efficiency of metal-oxyanion adsorption on TRM, as well as that the use of a TRM RB may improve the efficiency of contaminated soil remediation by means of electrokinesis."
1235368,Acevedo Aguilar et al. 2008,Analytical speciation of chromium in in-vitro cultures of chromate-resistant filamentous fungi,"In this work, different analytical speciation schemes have been used to study the reduction of Cr(VI) by a chromate-resistant strain of filamentous fungi Ed8 (Aspergillus sp), indigenous to contaminated industrial wastes. As demonstrated previously, this strain has the capability to reduce chromate present in the growth medium without its accumulation in the biomass, yet the reduced chromium end-products have not been characterized. Liquid growth medium, initially containing 50 mg L(-1) Cr(VI), was analyzed for Cr(III)/Cr(VI) and for total Cr at different time intervals (0-24 h) after inoculation with fungi. Three hyphenated procedures, based on the Cr(III)-EDTA formation and species separation by anion-exchange or ion-pairing reversed-phase chromatography with ICP-MS or DAD detection were used. The results obtained for Cr(VI) in each case were consistent, demonstrating efficient reduction of chromate during 24 h of Ed8 growth. However, pre-column complexation with EDTA did not ensure complete recovery of the reduced forms of chromium in the above procedures. An alternative speciation scheme, based on extraction of Cr(VI)-benzyltributylammonium bromide (BTAB) ion pairs into chloroform and subsequent determination of residual chromium by ICP-MS has provided evidence on the effective conversion of chromate into reduced chromium species in the growth medium. The results indicate the feasibility of using Ed8 strain for chromate bioremediation purposes. Analytically it can be concluded that speciation of chromium in biological systems should not be limited to its two most common oxidation states, because the actual reduced chromium species are not converted quantitatively to Cr(III)-EDTA.","Analytical speciation of chromium in in-vitro cultures of chromate-resistant filamentous fungi Abs: In this work, different analytical speciation schemes have been used to study the reduction of Cr(VI) by a chromate-resistant strain of filamentous fungi Ed8 (Aspergillus sp), indigenous to contaminated industrial wastes. As demonstrated previously, this strain has the capability to reduce chromate present in the growth medium without its accumulation in the biomass, yet the reduced chromium end-products have not been characterized. Liquid growth medium, initially containing 50 mg L(-1) Cr(VI), was analyzed for Cr(III)/Cr(VI) and for total Cr at different time intervals (0-24 h) after inoculation with fungi. Three hyphenated procedures, based on the Cr(III)-EDTA formation and species separation by anion-exchange or ion-pairing reversed-phase chromatography with ICP-MS or DAD detection were used. The results obtained for Cr(VI) in each case were consistent, demonstrating efficient reduction of chromate during 24 h of Ed8 growth. However, pre-column complexation with EDTA did not ensure complete recovery of the reduced forms of chromium in the above procedures. An alternative speciation scheme, based on extraction of Cr(VI)-benzyltributylammonium bromide (BTAB) ion pairs into chloroform and subsequent determination of residual chromium by ICP-MS has provided evidence on the effective conversion of chromate into reduced chromium species in the growth medium. The results indicate the feasibility of using Ed8 strain for chromate bioremediation purposes. Analytically it can be concluded that speciation of chromium in biological systems should not be limited to its two most common oxidation states, because the actual reduced chromium species are not converted quantitatively to Cr(III)-EDTA."
1235362,Molokwane et al. 2008,Chromium (VI) reduction in activated sludge bacteria exposed to high chromium loading: Brits culture (South Africa),"A mixed-culture of bacteria collected from a wastewater treatment plant in Brits, North-West Province (South Africa) biocatalytically reduced Cr(VI) at much higher concentrations than previously observed in cultures isolated in North America. Cr(VI) reduction rate up to 8 times higher than the rate in previous cultures was achieved by the Brits culture under aerobic conditions. Near complete Cr(VI) reduction was observed in batches under initial concentrations up to 200mg Cr(VI)/L after incubation for 65h in aerobic cultures. Under anaerobic conditions up to 150mg Cr(VI)/L was completely removed after incubating for 130-155h. In the previous cultures, complete removal was only achieved in cultures at an initial Cr(VI) concentration lower than 30mg/L after incubation for 96-110h. Consortium cultures were characterised using 16S rRNA partial sequence analysis. Results showed that the Gram-positive Bacillus genera predominated under aerobic conditions with a small composition of the Gram-negative Microbacterium sp. More biodiversity was observed in anaerobic cultures with the marked appearance of Enterococcus, Arthrobacter, Paenibacillus and Oceanobacillus species. Experiments run on purified individual species did not achieve the same level of Cr(VI) reduction as observed in the original consortium from sludge indicating possible existence of interspecies interactions necessary for optimum Cr(VI) reduction. All Cr(VI) reduced was accounted for as Cr(III) with a small error range (2-6%).","Chromium (VI) reduction in activated sludge bacteria exposed to high chromium loading: Brits culture (South Africa) Abs: A mixed-culture of bacteria collected from a wastewater treatment plant in Brits, North-West Province (South Africa) biocatalytically reduced Cr(VI) at much higher concentrations than previously observed in cultures isolated in North America. Cr(VI) reduction rate up to 8 times higher than the rate in previous cultures was achieved by the Brits culture under aerobic conditions. Near complete Cr(VI) reduction was observed in batches under initial concentrations up to 200mg Cr(VI)/L after incubation for 65h in aerobic cultures. Under anaerobic conditions up to 150mg Cr(VI)/L was completely removed after incubating for 130-155h. In the previous cultures, complete removal was only achieved in cultures at an initial Cr(VI) concentration lower than 30mg/L after incubation for 96-110h. Consortium cultures were characterised using 16S rRNA partial sequence analysis. Results showed that the Gram-positive Bacillus genera predominated under aerobic conditions with a small composition of the Gram-negative Microbacterium sp. More biodiversity was observed in anaerobic cultures with the marked appearance of Enterococcus, Arthrobacter, Paenibacillus and Oceanobacillus species. Experiments run on purified individual species did not achieve the same level of Cr(VI) reduction as observed in the original consortium from sludge indicating possible existence of interspecies interactions necessary for optimum Cr(VI) reduction. All Cr(VI) reduced was accounted for as Cr(III) with a small error range (2-6%)."
1235361,Karamalidis and  Voudrias 2008,Anion leaching from refinery oily sludge and ash from incineration of oily sludge stabilized/solidified with cement. Part I. Experimental results,"This paper presents the leaching behavior of anions (SO4(2-) and CrO4(2-)) from refinery oily sludge and ash produced by incineration of oily sludge, stabilized/solidified (s/s) with two types of cement, 142.5 and 1142.5. Anion leaching was examined using a 5-step sequential toxicity characteristic leaching procedure (TCLP) test. A single TCLP extraction resulted in limited sulfate release (&lt;50 mg/L) for s/s ash and significant sulfate release (&lt;850 mg/L) for s/s oily sludge. Chromate release was &lt;1 mg/L for s/s ash and nondetectable for s/s oily sludge. The sequential TCLP tests resulted in increased leaching for both sulfate and chromate. In general,the increase of liquid-to-solid ratio (TCLP leachant-to-waste ratio) resulted in increased leaching of sulfate from solidified samples compared to untreated oily sludge, ash and cement. In contrast, chromate leaching decreased by s/s process. A qualitatively similar leaching behavior for SO4(2-), even for radically different wastes such as oily sludge and ash, solidified with two different types of cement was observed.","Anion leaching from refinery oily sludge and ash from incineration of oily sludge stabilized/solidified with cement. Part I. Experimental results Abs: This paper presents the leaching behavior of anions (SO4(2-) and CrO4(2-)) from refinery oily sludge and ash produced by incineration of oily sludge, stabilized/solidified (s/s) with two types of cement, 142.5 and 1142.5. Anion leaching was examined using a 5-step sequential toxicity characteristic leaching procedure (TCLP) test. A single TCLP extraction resulted in limited sulfate release (&lt;50 mg/L) for s/s ash and significant sulfate release (&lt;850 mg/L) for s/s oily sludge. Chromate release was &lt;1 mg/L for s/s ash and nondetectable for s/s oily sludge. The sequential TCLP tests resulted in increased leaching for both sulfate and chromate. In general,the increase of liquid-to-solid ratio (TCLP leachant-to-waste ratio) resulted in increased leaching of sulfate from solidified samples compared to untreated oily sludge, ash and cement. In contrast, chromate leaching decreased by s/s process. A qualitatively similar leaching behavior for SO4(2-), even for radically different wastes such as oily sludge and ash, solidified with two different types of cement was observed."
1235360,Karamalidis and  Voudrias 2008,Anion leaching from refinery oily sludge and ash from incineration of oily sludge stabilized/solidified with cement. Part II. Modeling,"This paper presents the modeling of anion leaching (SO4(2-) and CrO4(2-)) from refinery oily sludge and ash produced by incineration of oily sludge, stabilized/solidified (s/s) with two types of cement, 142.5 and 1142.5. Anion leaching was examined using a sequential toxicity characteristic leaching procedure (TCLP) test. To elucidate the mechanisms of sulfate and chromate leaching, we employed Visual MINTEQ, incorporating a multiple-problem setup. Specifically, 10-14 different problems, depending on the pH range of the leachates, were connected together in the same run. Each problem corresponded to one pH value of the leachate and the model run covered the pH range of the five sequential TCLP extractions. This modeling approach was tested using chemical equilibrium with or without sorption onto ferrihydrite. Good agreement between experimental and modeling results was obtained for sulfate leaching from solidified oily sludge and ash, considering surface complexation onto ferrihydrite on top of chemical equilibrium controlled by gypsum at pH &lt;11 and ettringite at pH &gt;11. Chromate leaching was described by chemical equilibrium, controlled by CaCrO4(s) (at pH &lt;11) and Cr(VI)ettringite (at pH &gt;11).","Anion leaching from refinery oily sludge and ash from incineration of oily sludge stabilized/solidified with cement. Part II. Modeling Abs: This paper presents the modeling of anion leaching (SO4(2-) and CrO4(2-)) from refinery oily sludge and ash produced by incineration of oily sludge, stabilized/solidified (s/s) with two types of cement, 142.5 and 1142.5. Anion leaching was examined using a sequential toxicity characteristic leaching procedure (TCLP) test. To elucidate the mechanisms of sulfate and chromate leaching, we employed Visual MINTEQ, incorporating a multiple-problem setup. Specifically, 10-14 different problems, depending on the pH range of the leachates, were connected together in the same run. Each problem corresponded to one pH value of the leachate and the model run covered the pH range of the five sequential TCLP extractions. This modeling approach was tested using chemical equilibrium with or without sorption onto ferrihydrite. Good agreement between experimental and modeling results was obtained for sulfate leaching from solidified oily sludge and ash, considering surface complexation onto ferrihydrite on top of chemical equilibrium controlled by gypsum at pH &lt;11 and ettringite at pH &gt;11. Chromate leaching was described by chemical equilibrium, controlled by CaCrO4(s) (at pH &lt;11) and Cr(VI)ettringite (at pH &gt;11)."
1235358,Pereira et al. 2008,Chromate causes sulfur starvation in yeast,"Chromate is a widespread pollutant as a waste of human activities. However, the mechanisms underlying its high toxicity are not clearly understood. In this work, we used the yeast Saccharomyces cerevisiae to analyse the physiological effects of chromate exposure in a eukaryote cell model. We show that chromate causes a strong decrease of sulfate assimilation and sulfur metabolite pools suggesting that cells experience sulfur starvation. As a consequence, nearly all enzymes of the sulfur pathway are highly induced as well as enzymes of the sulfur-sparing response such as Pdc6, the sulfur-poor pyruvate decarboxylase. The induction of Pdc6 was regulated at the mRNA level and dependent upon Met32, a coactivator of Met4, the transcriptional activator of the sulfur pathway. Finally, we found that chromate enters the cells mainly through sulfate transporters and competitively inhibits sulfate uptake. Also consistent with a competition between the two substrates, sulfate supplementation relieves chromate toxicity. However, the data suggest that the chromate-mediated sulfur depletion is not simply due to this competitive uptake but would also be the consequence of competitive metabolism between the two compounds presumably at another step of the sulfur assimilation pathway.","Chromate causes sulfur starvation in yeast Abs: Chromate is a widespread pollutant as a waste of human activities. However, the mechanisms underlying its high toxicity are not clearly understood. In this work, we used the yeast Saccharomyces cerevisiae to analyse the physiological effects of chromate exposure in a eukaryote cell model. We show that chromate causes a strong decrease of sulfate assimilation and sulfur metabolite pools suggesting that cells experience sulfur starvation. As a consequence, nearly all enzymes of the sulfur pathway are highly induced as well as enzymes of the sulfur-sparing response such as Pdc6, the sulfur-poor pyruvate decarboxylase. The induction of Pdc6 was regulated at the mRNA level and dependent upon Met32, a coactivator of Met4, the transcriptional activator of the sulfur pathway. Finally, we found that chromate enters the cells mainly through sulfate transporters and competitively inhibits sulfate uptake. Also consistent with a competition between the two substrates, sulfate supplementation relieves chromate toxicity. However, the data suggest that the chromate-mediated sulfur depletion is not simply due to this competitive uptake but would also be the consequence of competitive metabolism between the two compounds presumably at another step of the sulfur assimilation pathway."
1235357,Guttmann et al. 2008,Reduction with glutathione is a weakly mutagenic pathway in chromium(VI) metabolism,"Although reductive metabolism of Cr(VI) always results in the production of Cr(III) and extensive Cr-DNA binding, cellular studies have indicated that different reduction processes are not equivalent in the induction of mutagenic events. Here, we examined mutagenicity and formation of Cr-DNA damage by Cr(VI) activated in vitro by one of its important reducers, glutathione (GSH). Our main focus was on reactions containing 2 mM GSH, corresponding to its average concentration in CHO (1.8 mM) and V79 (2.6 mM) mutagenicity models. We found that Cr(VI) reduction by 2 mM GSH produced only weak mutagenic responses in pSP189 plasmids replicated in human fibroblasts. Reductive activation of Cr(VI) with 5 mM GSH resulted in approximately 4-times greater DNA adduct-normalized yield of mutations. Mutagenic DNA damage formed in GSH-chromate reactions was caused by nonoxidative mechanisms, as blocking of Cr-DNA adduction led to a complete loss of mutagenesis. All GSH-mediated reactions also lacked significant DNA single-strand breakage. We developed a sensitive HPLC procedure for the detection of GSH-Cr-DNA cross-links based on the dissociation of DNA-conjugated GSH by Cr(III) chelation and its derivatization with monobromobimane. Weak mutagenicity of 2 mM GSH reactions was associated with a low production of mutagenic GSH-Cr-DNA cross-links (5.0% of total Cr-DNA adducts). In agreement with their greater mutation-inducing ability, 5 mM GSH reactions generated 4-5 times higher levels of GSH-DNA cross-linking. Overall, our results indicate that chromate reduction by physiological concentrations of GSH is a weakly mutagenic process, which is consistent with low mutagenicity of Cr(VI) in ascorbate-deficient cells.","Reduction with glutathione is a weakly mutagenic pathway in chromium(VI) metabolism Abs: Although reductive metabolism of Cr(VI) always results in the production of Cr(III) and extensive Cr-DNA binding, cellular studies have indicated that different reduction processes are not equivalent in the induction of mutagenic events. Here, we examined mutagenicity and formation of Cr-DNA damage by Cr(VI) activated in vitro by one of its important reducers, glutathione (GSH). Our main focus was on reactions containing 2 mM GSH, corresponding to its average concentration in CHO (1.8 mM) and V79 (2.6 mM) mutagenicity models. We found that Cr(VI) reduction by 2 mM GSH produced only weak mutagenic responses in pSP189 plasmids replicated in human fibroblasts. Reductive activation of Cr(VI) with 5 mM GSH resulted in approximately 4-times greater DNA adduct-normalized yield of mutations. Mutagenic DNA damage formed in GSH-chromate reactions was caused by nonoxidative mechanisms, as blocking of Cr-DNA adduction led to a complete loss of mutagenesis. All GSH-mediated reactions also lacked significant DNA single-strand breakage. We developed a sensitive HPLC procedure for the detection of GSH-Cr-DNA cross-links based on the dissociation of DNA-conjugated GSH by Cr(III) chelation and its derivatization with monobromobimane. Weak mutagenicity of 2 mM GSH reactions was associated with a low production of mutagenic GSH-Cr-DNA cross-links (5.0% of total Cr-DNA adducts). In agreement with their greater mutation-inducing ability, 5 mM GSH reactions generated 4-5 times higher levels of GSH-DNA cross-linking. Overall, our results indicate that chromate reduction by physiological concentrations of GSH is a weakly mutagenic process, which is consistent with low mutagenicity of Cr(VI) in ascorbate-deficient cells."
1235351,Chourey et al. 2009,Comparative temporal proteomics of a response regulator (SO2426)-deficient strain and wild-type Shewanella oneidensis MR-1 during chromate transformation,"Predicted orphan response regulators encoded in the Shewanella oneidensis MR-1 genome are poorly understood from a cellular function perspective. Our previous transcriptomic and proteomic analyses demonstrated that an annotated DNA-binding response regulator, SO2426, was significantly up-regulated in wild-type S. oneidensis cells at both the mRNA and protein levels in response to acute chromate [Cr(VI)] challenge, suggesting a potential regulatory role for this protein in metal stress pathways. To investigate the impact of SO2426 activity on chromate stress response at a genome-wide scale, we describe here comparative and temporal proteome characterizations using multidimensional HPLC-MS/MS and statistical analysis to identify differentially expressed proteins in biological replicates of wild-type S. oneidensis MR-1 and a so2426 deletion (Deltaso2426) strain, which exhibited an impaired Cr(VI) transformation rate compared to that of the parental strain. Global protein profiles were examined at different time intervals (0, 1, 3, 4 h) following exogenous chromate challenge. Results indicated that deletion of the so2426 gene negatively affected expression of a small protein subset (27 proteins) including those with annotated functions in siderophore biosynthesis (SO3032), Fe uptake (SO4743), intracellular Fe storage (Bfr1), and other transport processes. Cr(VI) exposure and subsequent transformation dramatically increased the number of differentially expressed proteins detected, with up-regulated abundance patterns observed largely for proteins involved in general stress protection and detoxification strategies, cell motility, and protein fate. In addition, the proteome data sets were mined for amino acids with potential post-translational modifications (PTMs) indicative of a level of gene expression regulation extending beyond the transcriptional control imposed by SO2426.","Comparative temporal proteomics of a response regulator (SO2426)-deficient strain and wild-type Shewanella oneidensis MR-1 during chromate transformation Abs: Predicted orphan response regulators encoded in the Shewanella oneidensis MR-1 genome are poorly understood from a cellular function perspective. Our previous transcriptomic and proteomic analyses demonstrated that an annotated DNA-binding response regulator, SO2426, was significantly up-regulated in wild-type S. oneidensis cells at both the mRNA and protein levels in response to acute chromate [Cr(VI)] challenge, suggesting a potential regulatory role for this protein in metal stress pathways. To investigate the impact of SO2426 activity on chromate stress response at a genome-wide scale, we describe here comparative and temporal proteome characterizations using multidimensional HPLC-MS/MS and statistical analysis to identify differentially expressed proteins in biological replicates of wild-type S. oneidensis MR-1 and a so2426 deletion (Deltaso2426) strain, which exhibited an impaired Cr(VI) transformation rate compared to that of the parental strain. Global protein profiles were examined at different time intervals (0, 1, 3, 4 h) following exogenous chromate challenge. Results indicated that deletion of the so2426 gene negatively affected expression of a small protein subset (27 proteins) including those with annotated functions in siderophore biosynthesis (SO3032), Fe uptake (SO4743), intracellular Fe storage (Bfr1), and other transport processes. Cr(VI) exposure and subsequent transformation dramatically increased the number of differentially expressed proteins detected, with up-regulated abundance patterns observed largely for proteins involved in general stress protection and detoxification strategies, cell motility, and protein fate. In addition, the proteome data sets were mined for amino acids with potential post-translational modifications (PTMs) indicative of a level of gene expression regulation extending beyond the transcriptional control imposed by SO2426."
1235350,Sannino et al. 2009,"Sorption of arsenate and dichromate on polymerin, Fe(OH)x-polymerin complex and ferrihydrite","Dihydrogenarsenate [H(2)AsO(4)(-), As(V)] or dichromate [Cr(2)O(7)(2-), Cr(VI)] at pH=4.0 showed to be sorbed on a Fe(OH)(x)-polymerin complex and ferrihydrite to a greater extent than on polymerin, the organic polymeric fraction of olive oil mill wastewater (OMW). In particular, the maximum amount (x(m)) of arsenate sorbed on Fe(OH)(x)-polymerin complex was similar to that on ferrihydrite (880.26 and 743.02 mmol kg(-1), respectively), and was much greater than that sorbed on polymerin (384.25 mmol kg(-1)). The sorption of dichromate was to a comparable extent on Fe(OH)(x)-polymerin complex and ferrihydrite (205.90 and 254.88 mmol kg(-1), respectively). Cr(III), a less toxic chromium form, mainly, and Cr(V) were indeed the effective forms sorbed on polymerin (200 mmol kg(-1)), as a consequence of the redox reaction of the strongly toxic Cr(VI) with the CH(2)OH groups of the polysaccharide moiety of this bio-sorbent, according to the data deriving from XPS and DRIFT analyses. The potential exploitation of the selected sorbents for the removal of As(V) or Cr(VI) from aqueous effluents is briefly discussed.","Sorption of arsenate and dichromate on polymerin, Fe(OH)x-polymerin complex and ferrihydrite Abs: Dihydrogenarsenate [H(2)AsO(4)(-), As(V)] or dichromate [Cr(2)O(7)(2-), Cr(VI)] at pH=4.0 showed to be sorbed on a Fe(OH)(x)-polymerin complex and ferrihydrite to a greater extent than on polymerin, the organic polymeric fraction of olive oil mill wastewater (OMW). In particular, the maximum amount (x(m)) of arsenate sorbed on Fe(OH)(x)-polymerin complex was similar to that on ferrihydrite (880.26 and 743.02 mmol kg(-1), respectively), and was much greater than that sorbed on polymerin (384.25 mmol kg(-1)). The sorption of dichromate was to a comparable extent on Fe(OH)(x)-polymerin complex and ferrihydrite (205.90 and 254.88 mmol kg(-1), respectively). Cr(III), a less toxic chromium form, mainly, and Cr(V) were indeed the effective forms sorbed on polymerin (200 mmol kg(-1)), as a consequence of the redox reaction of the strongly toxic Cr(VI) with the CH(2)OH groups of the polysaccharide moiety of this bio-sorbent, according to the data deriving from XPS and DRIFT analyses. The potential exploitation of the selected sorbents for the removal of As(V) or Cr(VI) from aqueous effluents is briefly discussed."
1235345,Verma et al. 2009,Genetic correlation between chromium resistance and reduction in Bacillus brevis isolated from tannery effluent,"<strong>AIMS: </strong>To investigate the genetic basis of Cr(VI) resistance and its reduction to Cr(III) in indigenous bacteria isolated from tannery effluent.<br /><br /><strong>METHODS AND RESULTS: </strong>Four bacteria resistant to high Cr(VI) levels were isolated and identified as Bacillus spp. Their Cr(VI) reduction ability was tested. To assess the genetic basis of Cr(VI) resistance and reduction, plasmid transfer and curing studies were performed. Among all, B. brevis was resistant to 180 microg Cr(VI) ml(-1) and showed the greatest degree of Cr(VI) reduction (75.8%) within 28 h and its transformant was resistant to 160 microg Cr(VI) ml(-1) and reduced 69.9% chromate. It harboured a stable 18 kb plasmid DNA. Transfer and curing studies revealed that both the chromate resistance and reduction were plasmid mediated. The presence of other metal cations did not have any significant effect on Cr(VI) bioreduction.<br /><br /><strong>CONCLUSIONS: </strong>Bacillus brevis was resistant to elevated Cr(VI) levels and may potentially reduce it in short time from an environment where other metal ions are also present in addition to chromium ions. The strain tested shows a positive correlation between genetic basis of Cr(VI) resistance and reduction.<br /><br /><strong>SIGNIFICANCE AND IMPACT OF THE STUDY: </strong>To our knowledge, this is the first study on the genetic correlation between chromium resistance and reduction in bacteria. Such strains may potentially be useful in biotechnological applications and in situ Cr(VI) bioremediation.","Genetic correlation between chromium resistance and reduction in Bacillus brevis isolated from tannery effluent Abs: <strong>AIMS: </strong>To investigate the genetic basis of Cr(VI) resistance and its reduction to Cr(III) in indigenous bacteria isolated from tannery effluent.<br /><br /><strong>METHODS AND RESULTS: </strong>Four bacteria resistant to high Cr(VI) levels were isolated and identified as Bacillus spp. Their Cr(VI) reduction ability was tested. To assess the genetic basis of Cr(VI) resistance and reduction, plasmid transfer and curing studies were performed. Among all, B. brevis was resistant to 180 microg Cr(VI) ml(-1) and showed the greatest degree of Cr(VI) reduction (75.8%) within 28 h and its transformant was resistant to 160 microg Cr(VI) ml(-1) and reduced 69.9% chromate. It harboured a stable 18 kb plasmid DNA. Transfer and curing studies revealed that both the chromate resistance and reduction were plasmid mediated. The presence of other metal cations did not have any significant effect on Cr(VI) bioreduction.<br /><br /><strong>CONCLUSIONS: </strong>Bacillus brevis was resistant to elevated Cr(VI) levels and may potentially reduce it in short time from an environment where other metal ions are also present in addition to chromium ions. The strain tested shows a positive correlation between genetic basis of Cr(VI) resistance and reduction.<br /><br /><strong>SIGNIFICANCE AND IMPACT OF THE STUDY: </strong>To our knowledge, this is the first study on the genetic correlation between chromium resistance and reduction in bacteria. Such strains may potentially be useful in biotechnological applications and in situ Cr(VI) bioremediation."
1235343,Hong et al. 2009,Removal of anionic contaminants by surfactant modified powdered activated carbon (SM-PAC) combined with ultrafiltration,"A variety of inorganic contaminants may form toxic oxyanions in aqueous systems which pose significant hazard to human health and the ecosystem. In order to remove the oxyanions from aqueous stream effectively, surfactant-modified powdered activated carbon (SM-PAC) combined with ultrafiltration (UF) was proposed in this study. As the cationic surfactant, cetylpyridinium chloride (CPC), adsorbs on the surface of PAC, the zeta potential of PAC increases to +40 mV. Oxyanions such as chromate, ferricyanide and arsenate bind on SM-PAC by electrostatic interaction, then the contaminants bound with SM-PAC can be separated by UF membrane. 0.3 mM of chromate and ferricyanide are removed completely with 4.0 g/L of SM-PAC. In case of arsenate, the removal efficiency was lower than chromate and ferricyanide. It is considered that the competition occurs among anionic pollutants on the limited binding sites of SM-PAC and lower valence of arsenate results in the lower removal efficiency. High permeate flux is maintained during filtration. The spent SM-PAC was regenerated by the concentrated Cl(-) solutions. NaCl solution whose molar Cl(-) concentration is 1.4 times higher than the contaminants bound on SM-PAC was optimal for the regeneration. Regenerated SM-PAC exhibited similar adsorption capacity to fresh SM-PAC. SM-PAC combined with UF can effectively remove anionic contaminants. Moreover, the simple and efficient regeneration process is proposed.","Removal of anionic contaminants by surfactant modified powdered activated carbon (SM-PAC) combined with ultrafiltration Abs: A variety of inorganic contaminants may form toxic oxyanions in aqueous systems which pose significant hazard to human health and the ecosystem. In order to remove the oxyanions from aqueous stream effectively, surfactant-modified powdered activated carbon (SM-PAC) combined with ultrafiltration (UF) was proposed in this study. As the cationic surfactant, cetylpyridinium chloride (CPC), adsorbs on the surface of PAC, the zeta potential of PAC increases to +40 mV. Oxyanions such as chromate, ferricyanide and arsenate bind on SM-PAC by electrostatic interaction, then the contaminants bound with SM-PAC can be separated by UF membrane. 0.3 mM of chromate and ferricyanide are removed completely with 4.0 g/L of SM-PAC. In case of arsenate, the removal efficiency was lower than chromate and ferricyanide. It is considered that the competition occurs among anionic pollutants on the limited binding sites of SM-PAC and lower valence of arsenate results in the lower removal efficiency. High permeate flux is maintained during filtration. The spent SM-PAC was regenerated by the concentrated Cl(-) solutions. NaCl solution whose molar Cl(-) concentration is 1.4 times higher than the contaminants bound on SM-PAC was optimal for the regeneration. Regenerated SM-PAC exhibited similar adsorption capacity to fresh SM-PAC. SM-PAC combined with UF can effectively remove anionic contaminants. Moreover, the simple and efficient regeneration process is proposed."
1235338,Lin et al. 2009,Chromate reduction by zero-valent Al metal as catalyzed by polyoxometalate,"In spite of a high reduction potential of zero-valent Al (ZVAl), its ability to reduce Cr(VI), a widespread pollutant, to less toxic Cr(III) remains to be uncovered. In the present study, Cr(VI) reduction by ZVAl was conducted to evaluate the potential application of Al as a reductant for Cr(VI). Polyoxometalate (POM, HNa(2)PW(12)O(40)), a catalyst, was used to accelerate Cr(VI) reduction by Al. The reaction of 0.192mM Cr(VI) on ZVAl was investigated in the presence of N(2) or O(2) at pH 1. A slight decrease in Cr(VI) concentration was observed on as-received (uncleaned) ZVAl due to the presence of oxide layer with a low surface area (ca. 3.4x10(-3)m(2)/g) of ZVAl. On addition of 0.1mM POM, Cr(VI) reduction on uncleaned ZVAl increased significantly. This is attributed to the unique properties of POM, which has a Brphinsted acidity higher than usual inorganic acids such as H(2)SO(4) and HCl. Thus, POM could remove rapidly the oxidize layer on ZVAl, followed by acting as a shuttle for electron transfer from ZVAl to Cr(VI). Under a N(2) atmosphere, one- or two-electron reduction of POM by ZVAl was responsible for Cr(VI) reduction in the early stage of the reaction. However, during reaction with ZVAl over 120min, three-electron reduction of POM predominated over Cr(VI) reduction. On interaction of O(2) with reduced POM, the formation of H(2)O(2) was responsible for subsequent Cr(VI) reduction. The results suggest that POM is an efficient catalyst for Cr(VI) reduction by Al due to the extremely rapid consumption of reduced POM or H(2)O(2) by Cr(VI).","Chromate reduction by zero-valent Al metal as catalyzed by polyoxometalate Abs: In spite of a high reduction potential of zero-valent Al (ZVAl), its ability to reduce Cr(VI), a widespread pollutant, to less toxic Cr(III) remains to be uncovered. In the present study, Cr(VI) reduction by ZVAl was conducted to evaluate the potential application of Al as a reductant for Cr(VI). Polyoxometalate (POM, HNa(2)PW(12)O(40)), a catalyst, was used to accelerate Cr(VI) reduction by Al. The reaction of 0.192mM Cr(VI) on ZVAl was investigated in the presence of N(2) or O(2) at pH 1. A slight decrease in Cr(VI) concentration was observed on as-received (uncleaned) ZVAl due to the presence of oxide layer with a low surface area (ca. 3.4x10(-3)m(2)/g) of ZVAl. On addition of 0.1mM POM, Cr(VI) reduction on uncleaned ZVAl increased significantly. This is attributed to the unique properties of POM, which has a Brphinsted acidity higher than usual inorganic acids such as H(2)SO(4) and HCl. Thus, POM could remove rapidly the oxidize layer on ZVAl, followed by acting as a shuttle for electron transfer from ZVAl to Cr(VI). Under a N(2) atmosphere, one- or two-electron reduction of POM by ZVAl was responsible for Cr(VI) reduction in the early stage of the reaction. However, during reaction with ZVAl over 120min, three-electron reduction of POM predominated over Cr(VI) reduction. On interaction of O(2) with reduced POM, the formation of H(2)O(2) was responsible for subsequent Cr(VI) reduction. The results suggest that POM is an efficient catalyst for Cr(VI) reduction by Al due to the extremely rapid consumption of reduced POM or H(2)O(2) by Cr(VI)."
1235331,Cavallo et al. 2010,Direct-oxidative DNA damage and apoptosis induction in different human respiratory cells exposed to low concentrations of sodium chromate,"The mechanism of Cr(VI) genotoxicity has still not been elucidated. We used Fpg-modified comet assay to assess direct-oxidative DNA damage on human lung (A549) and bronchial (BEAS-2B) cells exposed to 0.1, 0.5, 1.0 and 10 microm sodium chromate for 0.5, 1 and 4 h. Moreover we evaluated apoptosis by morphological analysis and caspase-3 activity, also after 24 h. On A549 cells a time-dependent DNA damage, expressed as tail DNA%, beginning from 0.5 microm was found. For oxidative DNA damage an induction after 30 min to 0.5 microm decreasing with time, and a time-dependent increase at 10 microm was found, indicating for low Cr(VI) concentration the oxidative stress as the first event followed by direct DNA damage and for the highest concentration a time-dependent increase in oxidative DNA damage. On BEAS-2B cells DNA damage was induced within 1 h at 0.5-10 microm, without changes with time, showing that BEAS-2B cells are able to resist to Cr(VI) genotoxicity. Early oxidative DNA damage at 0.1 microm decreasing with time was also found. Significant apoptosis was observed by morphological analysis in A549 cells and to a lower extent in BEAS-2B at 10 microm. The exposure to 10 microm induced caspase-3 activity after 4 h in BEAS-2B and after 24 h in A549 cells. The findings show a higher responsiveness of A549 cells to genotoxic effect of Cr(VI) and early transient oxidative DNA damage in BEAS-2B. The results emphasize the suitability of this experimental model to evaluate the early genotoxic response of different cells to non-cytotoxic concentrations of Cr(VI) on target organ.","Direct-oxidative DNA damage and apoptosis induction in different human respiratory cells exposed to low concentrations of sodium chromate Abs: The mechanism of Cr(VI) genotoxicity has still not been elucidated. We used Fpg-modified comet assay to assess direct-oxidative DNA damage on human lung (A549) and bronchial (BEAS-2B) cells exposed to 0.1, 0.5, 1.0 and 10 microm sodium chromate for 0.5, 1 and 4 h. Moreover we evaluated apoptosis by morphological analysis and caspase-3 activity, also after 24 h. On A549 cells a time-dependent DNA damage, expressed as tail DNA%, beginning from 0.5 microm was found. For oxidative DNA damage an induction after 30 min to 0.5 microm decreasing with time, and a time-dependent increase at 10 microm was found, indicating for low Cr(VI) concentration the oxidative stress as the first event followed by direct DNA damage and for the highest concentration a time-dependent increase in oxidative DNA damage. On BEAS-2B cells DNA damage was induced within 1 h at 0.5-10 microm, without changes with time, showing that BEAS-2B cells are able to resist to Cr(VI) genotoxicity. Early oxidative DNA damage at 0.1 microm decreasing with time was also found. Significant apoptosis was observed by morphological analysis in A549 cells and to a lower extent in BEAS-2B at 10 microm. The exposure to 10 microm induced caspase-3 activity after 4 h in BEAS-2B and after 24 h in A549 cells. The findings show a higher responsiveness of A549 cells to genotoxic effect of Cr(VI) and early transient oxidative DNA damage in BEAS-2B. The results emphasize the suitability of this experimental model to evaluate the early genotoxic response of different cells to non-cytotoxic concentrations of Cr(VI) on target organ."
1235327,Dettmer et al. 2010,Production of basic chromium sulfate by using recovered chromium from ashes of thermally treated leather,"Leather wastes tanned with chromium are generated during the production process of leather, hence the wastes from hand crafted goods and footwear industries are a serious environmental problem. The thermal treatment of leather wastes can be one of the treatment options because the wastes are rich in chromium and can be used as a raw material for sodium chromate production and further to obtain several chromium compounds. The objective of this study was to utilize the chromium from leather wastes via basic chromium sulfate production to be subsequently applied in a hide tanning. The obtained results have shown that this is the first successful attempt to achieve desired base properties of the product. The result was achieved when the following conditions were applied: a molar ratio between sodium sulfite and sodium dichromate equal to 6; reaction time equal to 5 min before addition of sulfuric acid; pH of sodium dichromate solution equal to 2. Summarizing, there is an opportunity to utilize the dangerous wastes and reused them in the production scheme by minimizing or annulling the environmental impact and to attend a sustainable process development concept.","Production of basic chromium sulfate by using recovered chromium from ashes of thermally treated leather Abs: Leather wastes tanned with chromium are generated during the production process of leather, hence the wastes from hand crafted goods and footwear industries are a serious environmental problem. The thermal treatment of leather wastes can be one of the treatment options because the wastes are rich in chromium and can be used as a raw material for sodium chromate production and further to obtain several chromium compounds. The objective of this study was to utilize the chromium from leather wastes via basic chromium sulfate production to be subsequently applied in a hide tanning. The obtained results have shown that this is the first successful attempt to achieve desired base properties of the product. The result was achieved when the following conditions were applied: a molar ratio between sodium sulfite and sodium dichromate equal to 6; reaction time equal to 5 min before addition of sulfuric acid; pH of sodium dichromate solution equal to 2. Summarizing, there is an opportunity to utilize the dangerous wastes and reused them in the production scheme by minimizing or annulling the environmental impact and to attend a sustainable process development concept."
1235326,Weese 2009,Evaluation of exposure incident at the Qarmat Ali Water Treatment Plant,,Evaluation of exposure incident at the Qarmat Ali Water Treatment Plant Abs: 
1235323,Ksheminska et al. 2010,The chromate resistance phenotype of some yeast mutants correlates with a lower level of Cr(V)-species generated in the extra-cellular medium,"The paper describes the selection of chromate-resistant mutants of the yeast Pichia guilliermondii with a higher chromate-reducing activity and reports the EPR-study of Cr(V)-generation in the extra-cellular medium during the reduction of chromate by the yeast culture. It is shown that the reduction of chromate to Cr(III) species runs through the extra-cellular generation of Cr(V)-intermediate(s), thus supporting the assumption about the existence of an extra-cellular pathway of Cr(VI)-reduction. Furthermore, it is demonstrated that the chromate-resistance phenotype of tested mutants correlates with a lower stationary level of Cr(V)-species in the medium. It is thus suggested that isolated mutants can be used as sources of Cr(III)-biocomplexes due to their ability to effectively reduce chromate to Cr(III)-chelates with potential pharmacological applications.","The chromate resistance phenotype of some yeast mutants correlates with a lower level of Cr(V)-species generated in the extra-cellular medium Abs: The paper describes the selection of chromate-resistant mutants of the yeast Pichia guilliermondii with a higher chromate-reducing activity and reports the EPR-study of Cr(V)-generation in the extra-cellular medium during the reduction of chromate by the yeast culture. It is shown that the reduction of chromate to Cr(III) species runs through the extra-cellular generation of Cr(V)-intermediate(s), thus supporting the assumption about the existence of an extra-cellular pathway of Cr(VI)-reduction. Furthermore, it is demonstrated that the chromate-resistance phenotype of tested mutants correlates with a lower stationary level of Cr(V)-species in the medium. It is thus suggested that isolated mutants can be used as sources of Cr(III)-biocomplexes due to their ability to effectively reduce chromate to Cr(III)-chelates with potential pharmacological applications."
1235321,Francisco et al. 2010,Different physiological responses to chromate and dichromate in the chromium resistant and reducing strain Ochrobactrum tritici 5bvl1,"Studies of Cr(VI) toxicity are generally performed using chromate salts in solution, both when studying the effects on prokaryotes and eukaryotes. Some studies on human carcinogenesis and toxicology on bacteria were done using dichromate, but comparison with chromate was never reported before, and dichromate existence was never taken into consideration and usually overlooked. This paper studied comparatively the effect of dichromate and chromate on the physiology of Ochrobactrum tritici strain 5bvl1, a highly Cr(VI)-resistant and reducing microorganism. This study demonstrated that the addition of chromate or dichromate sodium salts to growth medium at neutral pH ended-up in two different solutions with a different balance of chemical species. Cr(VI) was toxic to O. tritici strain 5bvl1, as clearly shown on growth, reduction, respiration, glucose accumulation assays and by comparing cell morphology. Moreover, the addition of sodium dichromate was always more toxic to cells when compared to chromate and achieved a higher inhibition of every parameter studied. The toxicity differences between the two Cr(VI) oxyanions indicate the possibility of a different impact of Cr(VI) contamination on the environment. This may be of major importance, considering the slight acidity of most of the arable lands which favours the presence of dichromate, the more toxic species.","Different physiological responses to chromate and dichromate in the chromium resistant and reducing strain Ochrobactrum tritici 5bvl1 Abs: Studies of Cr(VI) toxicity are generally performed using chromate salts in solution, both when studying the effects on prokaryotes and eukaryotes. Some studies on human carcinogenesis and toxicology on bacteria were done using dichromate, but comparison with chromate was never reported before, and dichromate existence was never taken into consideration and usually overlooked. This paper studied comparatively the effect of dichromate and chromate on the physiology of Ochrobactrum tritici strain 5bvl1, a highly Cr(VI)-resistant and reducing microorganism. This study demonstrated that the addition of chromate or dichromate sodium salts to growth medium at neutral pH ended-up in two different solutions with a different balance of chemical species. Cr(VI) was toxic to O. tritici strain 5bvl1, as clearly shown on growth, reduction, respiration, glucose accumulation assays and by comparing cell morphology. Moreover, the addition of sodium dichromate was always more toxic to cells when compared to chromate and achieved a higher inhibition of every parameter studied. The toxicity differences between the two Cr(VI) oxyanions indicate the possibility of a different impact of Cr(VI) contamination on the environment. This may be of major importance, considering the slight acidity of most of the arable lands which favours the presence of dichromate, the more toxic species."
1235320,Saeki et al. 2010,Removal of aqueous chromate [Cr(VI)] through photocatalysis by using TiO2-coated silica granules,"The aim of this study was to determine the optimal conditions for the treatment of chromate [Cr(VI)]- contaminated water by UV photocatalysis using synthesized TiO(2)-coated silica granules (phi 1.7-4.0 mm) containing 12.4% of TiO(2) in a batch method. The effect of the volume of the solution on Cr(VI) removal was investigated in the photocatalysis process by using 10 g of TiO(2)-coated silica granules in water samples with a constant initial Cr(VI) concentration of 5 mg L(-1). In a 10-mL solution, Cr(VI) concentrations were observed to decrease below the detection limit (&lt; 0.05 mg L(-1)) in 300 min. Furthermore, Cr(VI) concentrations gradually decreased with time in other solutions with larger volumes. The capacity of the UV photocatalysis process to remove Cr(VI) using 10 g of TiO(2)-coated granules did not fluctuate with the solution volume for samples with a constant initial Cr(VI) concentration. The lower the initial pH of the solution, the greater was the amount of Cr(VI) removed from the solution. The addition of chloride ions to the solutions accelerated the removal of Cr(VI) by UV photocatalysis. Ten grams of TiO(2)-coated silica granules were repeatedly used to the 300-min treatment of the Cr(VI) solution (10 mL, 6 mg L(-1)) till seven cycles. After four cycles of UV photocatalysis, Cr(VI) was completely removed from all the solutions. After the fifth cycle, the Cr(VI) removal capacity of the UV photocatalysis process decreased with the repeated use of the catalyst.","Removal of aqueous chromate [Cr(VI)] through photocatalysis by using TiO2-coated silica granules Abs: The aim of this study was to determine the optimal conditions for the treatment of chromate [Cr(VI)]- contaminated water by UV photocatalysis using synthesized TiO(2)-coated silica granules (phi 1.7-4.0 mm) containing 12.4% of TiO(2) in a batch method. The effect of the volume of the solution on Cr(VI) removal was investigated in the photocatalysis process by using 10 g of TiO(2)-coated silica granules in water samples with a constant initial Cr(VI) concentration of 5 mg L(-1). In a 10-mL solution, Cr(VI) concentrations were observed to decrease below the detection limit (&lt; 0.05 mg L(-1)) in 300 min. Furthermore, Cr(VI) concentrations gradually decreased with time in other solutions with larger volumes. The capacity of the UV photocatalysis process to remove Cr(VI) using 10 g of TiO(2)-coated granules did not fluctuate with the solution volume for samples with a constant initial Cr(VI) concentration. The lower the initial pH of the solution, the greater was the amount of Cr(VI) removed from the solution. The addition of chloride ions to the solutions accelerated the removal of Cr(VI) by UV photocatalysis. Ten grams of TiO(2)-coated silica granules were repeatedly used to the 300-min treatment of the Cr(VI) solution (10 mL, 6 mg L(-1)) till seven cycles. After four cycles of UV photocatalysis, Cr(VI) was completely removed from all the solutions. After the fifth cycle, the Cr(VI) removal capacity of the UV photocatalysis process decreased with the repeated use of the catalyst."
1235318,Zecevic et al. 2010,XPA impacts formation but not proteasome-sensitive repair of DNA-protein cross-links induced by chromate,"DNA-protein cross-links (DPCs) are caused by a large number of human carcinogens and anti-cancer drugs. However, cellular processes involved in decreasing a burden of these genotoxic lesions remain poorly understood. Here, we examined the impact of nucleotide excision repair (NER), which is a principal repair pathway for bulky DNA adducts, and the main cellular reducers on removal of chromium(VI)-induced DPC. We found that standard and ascorbate-restored cultures of isogenic XPA-null (NER deficient) and XPA-complemented human fibroblasts had very similar repair of Cr-DPC (60-65% average DPC removal after 24 h). However, XPA absence caused depletion of G1 and accumulation of G2 cells at low Cr(VI) doses, suggesting that Cr-DPC were not a significant cause of cell cycle perturbations. Interestingly, although pro-oxidant metabolism of Cr(VI) in glutathione-depleted cells generated significantly fewer DPC, they were repair resistant irrespective of the NER status of cells. Inhibition of proteasome activity by MG132 abolished DPC repair in both XPA-null and XPA-complemented cells. XPA loss caused two to three times higher initial DPC formation, demonstrating the importance of NER in removal of the precursor lesions. Our results indicate that human NER is not involved in removal of Cr-DPC containing non-histone proteins but it acts as a defence mechanism against these large lesions by preventing their formation. Therefore, individual differences in NER activity are expected to alter sensitivity but not persistence of DPC as a biomarker of hexavalent Cr.","XPA impacts formation but not proteasome-sensitive repair of DNA-protein cross-links induced by chromate Abs: DNA-protein cross-links (DPCs) are caused by a large number of human carcinogens and anti-cancer drugs. However, cellular processes involved in decreasing a burden of these genotoxic lesions remain poorly understood. Here, we examined the impact of nucleotide excision repair (NER), which is a principal repair pathway for bulky DNA adducts, and the main cellular reducers on removal of chromium(VI)-induced DPC. We found that standard and ascorbate-restored cultures of isogenic XPA-null (NER deficient) and XPA-complemented human fibroblasts had very similar repair of Cr-DPC (60-65% average DPC removal after 24 h). However, XPA absence caused depletion of G1 and accumulation of G2 cells at low Cr(VI) doses, suggesting that Cr-DPC were not a significant cause of cell cycle perturbations. Interestingly, although pro-oxidant metabolism of Cr(VI) in glutathione-depleted cells generated significantly fewer DPC, they were repair resistant irrespective of the NER status of cells. Inhibition of proteasome activity by MG132 abolished DPC repair in both XPA-null and XPA-complemented cells. XPA loss caused two to three times higher initial DPC formation, demonstrating the importance of NER in removal of the precursor lesions. Our results indicate that human NER is not involved in removal of Cr-DPC containing non-histone proteins but it acts as a defence mechanism against these large lesions by preventing their formation. Therefore, individual differences in NER activity are expected to alter sensitivity but not persistence of DPC as a biomarker of hexavalent Cr."
1235316,Thompson et al. 2010,Proteomics reveals a core molecular response of Pseudomonas putida F1 to acute chromate challenge,"<strong>BACKGROUND: </strong>Pseudomonas putida is a model organism for bioremediation because of its remarkable metabolic versatility, extensive biodegradative functions, and ubiquity in contaminated soil environments. To further the understanding of molecular pathways responding to the heavy metal chromium(VI) [Cr(VI)], the proteome of aerobically grown, Cr(VI)-stressed P. putida strain F1 was characterized within the context of two disparate nutritional environments: rich (LB) media and minimal (M9L) media containing lactate as the sole carbon source.<br /><br /><strong>RESULTS: </strong>Growth studies demonstrated that F1 sensitivity to Cr(VI) was impacted substantially by nutrient conditions, with a carbon-source-dependent hierarchy (lactate &gt; glucose &gt; acetate) observed in minimal media. Two-dimensional HPLC-MS/MS was employed to identify differential proteome profiles generated in response to 1 mM chromate under LB and M9L growth conditions. The immediate response to Cr(VI) in LB-grown cells was up-regulation of proteins involved in inorganic ion transport, secondary metabolite biosynthesis and catabolism, and amino acid metabolism. By contrast, the chromate-responsive proteome derived under defined minimal growth conditions was characterized predominantly by up-regulated proteins related to cell envelope biogenesis, inorganic ion transport, and motility. TonB-dependent siderophore receptors involved in ferric iron acquisition and amino acid adenylation domains characterized up-regulated systems under LB-Cr(VI) conditions, while DNA repair proteins and systems scavenging sulfur from alternative sources (e.g., aliphatic sulfonates) tended to predominate the up-regulated proteome profile obtained under M9L-Cr(VI) conditions.<br /><br /><strong>CONCLUSIONS: </strong>Comparative analysis indicated that the core molecular response to chromate, irrespective of the nutritional conditions tested, comprised seven up-regulated proteins belonging to six different functional categories including transcription, inorganic ion transport/metabolism, and amino acid transport/metabolism. These proteins might potentially serve as indicators of chromate stress in natural microbial communities.","Proteomics reveals a core molecular response of Pseudomonas putida F1 to acute chromate challenge Abs: <strong>BACKGROUND: </strong>Pseudomonas putida is a model organism for bioremediation because of its remarkable metabolic versatility, extensive biodegradative functions, and ubiquity in contaminated soil environments. To further the understanding of molecular pathways responding to the heavy metal chromium(VI) [Cr(VI)], the proteome of aerobically grown, Cr(VI)-stressed P. putida strain F1 was characterized within the context of two disparate nutritional environments: rich (LB) media and minimal (M9L) media containing lactate as the sole carbon source.<br /><br /><strong>RESULTS: </strong>Growth studies demonstrated that F1 sensitivity to Cr(VI) was impacted substantially by nutrient conditions, with a carbon-source-dependent hierarchy (lactate &gt; glucose &gt; acetate) observed in minimal media. Two-dimensional HPLC-MS/MS was employed to identify differential proteome profiles generated in response to 1 mM chromate under LB and M9L growth conditions. The immediate response to Cr(VI) in LB-grown cells was up-regulation of proteins involved in inorganic ion transport, secondary metabolite biosynthesis and catabolism, and amino acid metabolism. By contrast, the chromate-responsive proteome derived under defined minimal growth conditions was characterized predominantly by up-regulated proteins related to cell envelope biogenesis, inorganic ion transport, and motility. TonB-dependent siderophore receptors involved in ferric iron acquisition and amino acid adenylation domains characterized up-regulated systems under LB-Cr(VI) conditions, while DNA repair proteins and systems scavenging sulfur from alternative sources (e.g., aliphatic sulfonates) tended to predominate the up-regulated proteome profile obtained under M9L-Cr(VI) conditions.<br /><br /><strong>CONCLUSIONS: </strong>Comparative analysis indicated that the core molecular response to chromate, irrespective of the nutritional conditions tested, comprised seven up-regulated proteins belonging to six different functional categories including transcription, inorganic ion transport/metabolism, and amino acid transport/metabolism. These proteins might potentially serve as indicators of chromate stress in natural microbial communities."
1235312,Magnuson et al. 2010,"Proteogenomic and functional analysis of chromate reduction in Acidiphilium cryptum JF-5, an Fe(III)-respiring acidophile","Acidiphilium cryptum JF-5, an acidophilic iron-respiring Alphaproteobacterium, has the ability to reduce chromate under aerobic and anaerobic conditions, making it an intriguing and useful model organism for the study of extremophilic bacteria in bioremediation applications. Genome sequence annotation suggested two potential mechanisms of Cr(VI) reduction, namely, a number of c-type cytochromes, and a predicted NADPH-dependent Cr(VI) reductase. In laboratory studies using pure cultures of JF-5, an NADPH-dependent chromate reductase activity was detected primarily in soluble protein fractions, and a periplasmic c-type cytochrome (ApcA) was also present, representing two potential means of Cr(VI) reduction. Upon further examination, it was determined that the NADPH-dependent activity was not specific for Cr(VI), and the predicted proteins were not detected in Cr(VI)-grown cultures. Proteomic data did show measureable amounts of ApcA in cells grown with Cr(VI). Purified ApcA is reducible by menadiol, and in turn can reduce Cr(VI), suggesting a means to obtain electrons from the respiratory chain and divert them to Cr(VI). Electrochemical measurements confirm that Cr reduction by ApcA is pH dependent, with low pH being favored. Homology modeling of ApcA and comparison to a known Cr(VI)-reducing c-type cytochrome structure revealed basic amino acids which could interact with chromate ion. From these studies, it can be concluded that A. cryptum has the physiologic and genomic capability to reduce Cr(VI) to the less toxic Cr(III). However, the expected chromate reductase mechanism may not be the primary means of Cr(VI) reduction in this organism.","Proteogenomic and functional analysis of chromate reduction in Acidiphilium cryptum JF-5, an Fe(III)-respiring acidophile Abs: Acidiphilium cryptum JF-5, an acidophilic iron-respiring Alphaproteobacterium, has the ability to reduce chromate under aerobic and anaerobic conditions, making it an intriguing and useful model organism for the study of extremophilic bacteria in bioremediation applications. Genome sequence annotation suggested two potential mechanisms of Cr(VI) reduction, namely, a number of c-type cytochromes, and a predicted NADPH-dependent Cr(VI) reductase. In laboratory studies using pure cultures of JF-5, an NADPH-dependent chromate reductase activity was detected primarily in soluble protein fractions, and a periplasmic c-type cytochrome (ApcA) was also present, representing two potential means of Cr(VI) reduction. Upon further examination, it was determined that the NADPH-dependent activity was not specific for Cr(VI), and the predicted proteins were not detected in Cr(VI)-grown cultures. Proteomic data did show measureable amounts of ApcA in cells grown with Cr(VI). Purified ApcA is reducible by menadiol, and in turn can reduce Cr(VI), suggesting a means to obtain electrons from the respiratory chain and divert them to Cr(VI). Electrochemical measurements confirm that Cr reduction by ApcA is pH dependent, with low pH being favored. Homology modeling of ApcA and comparison to a known Cr(VI)-reducing c-type cytochrome structure revealed basic amino acids which could interact with chromate ion. From these studies, it can be concluded that A. cryptum has the physiologic and genomic capability to reduce Cr(VI) to the less toxic Cr(III). However, the expected chromate reductase mechanism may not be the primary means of Cr(VI) reduction in this organism."
1235309,Marin et al. 2010,Potentially deadly carcinogenic chromium redox cycle involving peroxochromium(IV) and glutathione,"Peroxochromium(IV) complexes are putative DNA-damaging and mutagenic agents in chromium(VI)-mediated carcinogenesis. The reaction between aquaethylenediaminebis(peroxo)chromium(IV) and glutathione at neutral pH exhibits a cyclic redox process displaying a persistent recycling of Cr(IV) and Cr(VI) with the intervention of chromium(V) intermediates. The coordination by a glutathione molecule triggers an autooxidation of the Cr(IV)-peroxo complex to Cr(VI) via an internal electron-transfer process followed by reduction to Cr(IV) via metastable chromium(V) intermediates. The cycle is repeated by the second peroxo species. The Cr(V) and -(IV) intermediates have been characterized as mono- and bisglutathionato complexes with or without a coordinated peroxo moiety. These intermediates are capable of damaging DNA, as evidenced by single strand breaks and DNA oxidation. The implication here is that the potential for a persistent, if not perpetual, deadly chromium carcinogenic cycle exists in the cellular milieu through the assistance of molecular oxygen and glutathione.","Potentially deadly carcinogenic chromium redox cycle involving peroxochromium(IV) and glutathione Abs: Peroxochromium(IV) complexes are putative DNA-damaging and mutagenic agents in chromium(VI)-mediated carcinogenesis. The reaction between aquaethylenediaminebis(peroxo)chromium(IV) and glutathione at neutral pH exhibits a cyclic redox process displaying a persistent recycling of Cr(IV) and Cr(VI) with the intervention of chromium(V) intermediates. The coordination by a glutathione molecule triggers an autooxidation of the Cr(IV)-peroxo complex to Cr(VI) via an internal electron-transfer process followed by reduction to Cr(IV) via metastable chromium(V) intermediates. The cycle is repeated by the second peroxo species. The Cr(V) and -(IV) intermediates have been characterized as mono- and bisglutathionato complexes with or without a coordinated peroxo moiety. These intermediates are capable of damaging DNA, as evidenced by single strand breaks and DNA oxidation. The implication here is that the potential for a persistent, if not perpetual, deadly chromium carcinogenic cycle exists in the cellular milieu through the assistance of molecular oxygen and glutathione."
1235304,Yazdanbakhsh et al. 2010,Fabrication of nanospinel ZnCr2O4 using sol-gel method and its application on removal of azo dye from aqueous solution,"For the first time, nanoparticles of zinc chromite, spinel ZnCr(2)O(4) have been fabricated by the thermal decomposition of Zn-Cr gel prepared by sol-gel method in the presence of oxalic acid as a chelating agent. It was shown that the well-crystallized spinel structure is formed after calcination at 450°C. The nanospinel has been characterized by differential thermal analysis (DTA), X-ray powder diffraction (XRD), infrared spectroscopy (IR), and transmission electron microscope (TEM). The average particle size is approximately 13 nm according to the TEM image. The nanoparticles of zinc chromites showed excellent adsorption properties towards reactive dye, reactive blue 5 (RB5). The adsorption studies have been carried out for contact time, different pH values, different temperatures, and adsorbent doses. The investigation of removal kinetics of RB5 indicates that the removal process obeys the rate of second-order kinetic equation. The results indicate that the Langmuir adsorption isotherm fitted the data better than the Freundlich. Also, the photocatalytic degradation of RB5 using spinel ZnCr(2)O(4) under UV irradiation at pH=1 has been also examined. The results showed that the degradation of RB5 dye follows merely an adsorption process.","Fabrication of nanospinel ZnCr2O4 using sol-gel method and its application on removal of azo dye from aqueous solution Abs: For the first time, nanoparticles of zinc chromite, spinel ZnCr(2)O(4) have been fabricated by the thermal decomposition of Zn-Cr gel prepared by sol-gel method in the presence of oxalic acid as a chelating agent. It was shown that the well-crystallized spinel structure is formed after calcination at 450°C. The nanospinel has been characterized by differential thermal analysis (DTA), X-ray powder diffraction (XRD), infrared spectroscopy (IR), and transmission electron microscope (TEM). The average particle size is approximately 13 nm according to the TEM image. The nanoparticles of zinc chromites showed excellent adsorption properties towards reactive dye, reactive blue 5 (RB5). The adsorption studies have been carried out for contact time, different pH values, different temperatures, and adsorbent doses. The investigation of removal kinetics of RB5 indicates that the removal process obeys the rate of second-order kinetic equation. The results indicate that the Langmuir adsorption isotherm fitted the data better than the Freundlich. Also, the photocatalytic degradation of RB5 using spinel ZnCr(2)O(4) under UV irradiation at pH=1 has been also examined. The results showed that the degradation of RB5 dye follows merely an adsorption process."
1235292,Smutok et al. 2011,Chromate-reducing activity of Hansenula polymorpha recombinant cells over-producing flavocytochrome b?,"In spite of the great interest to studies of the biological roles of chromium, as well as the toxic influence of Cr(VI)-species on living organisms, the molecular mechanisms of chromate bioremediation remain vague. A reductive pathway resulting in formation of less toxic Cr(III)-species is suggested to be the most important among possible mechanisms for chromate biodetoxification. The yeast l-lactate:cytochrome c-oxidoreductase (flavocytochrome b(2), FC b(2)) has absolute specificity for l-lactate, yet is non-selective with respect to its electron acceptor. These properties allow us to consider the enzyme as a potential candidate for chromate reduction by living cells in the presence of l-lactate. A recombinant strain of thermotolerant, methylotrophic yeast Hansenula polymorpha with sixfold increased FC b(2) enzyme activity (up to 3?molmin(-1)mg(-1) protein in cell-free extract) compared to the parental strain was used for approval our suggestion. The recombinant cells, stored in dried state, as well as living yeast cells were tested for chromate-reducing activity in vitro in the presence of l-lactate (as an electron donor for chromate reduction) and different low molecular weight, redox-active mediators facilitating electron transfer from the reduced form of the enzyme to chromate (as a final electron acceptor): dichlorophenolindophenol (DCPIP), Methylene blue, Meldola blue, and Nile blue. It was shown that the highest chromate-reducing activity of the cells was achieved in the presence of DCPIP. The ability of chromate to catch electrons from the reduced flavocytochrome b(2) was confirmed using purified enzyme immobilized on the surface of a platinum electrode. The increasing concentration of Cr(VI) resulted in a decrease of enzyme-mediated current generated on the electrode during l-lactate oxidation. The shift and drop in amplitude of the peak in the cyclic voltammogram are indicative of Cr(VI)-dependent competition between reaction of chromate with reduced FC b(2) and direct electron transfer from the enzyme to the electrode surface. The application of the chromate-reducing ability of FC b(2)-over-producing recombinant cells of H. polymorpha toward chromate bioremediation and the construction of cells-based biosensor for chromate monitoring in the environment are discussed.","Chromate-reducing activity of Hansenula polymorpha recombinant cells over-producing flavocytochrome b? Abs: In spite of the great interest to studies of the biological roles of chromium, as well as the toxic influence of Cr(VI)-species on living organisms, the molecular mechanisms of chromate bioremediation remain vague. A reductive pathway resulting in formation of less toxic Cr(III)-species is suggested to be the most important among possible mechanisms for chromate biodetoxification. The yeast l-lactate:cytochrome c-oxidoreductase (flavocytochrome b(2), FC b(2)) has absolute specificity for l-lactate, yet is non-selective with respect to its electron acceptor. These properties allow us to consider the enzyme as a potential candidate for chromate reduction by living cells in the presence of l-lactate. A recombinant strain of thermotolerant, methylotrophic yeast Hansenula polymorpha with sixfold increased FC b(2) enzyme activity (up to 3?molmin(-1)mg(-1) protein in cell-free extract) compared to the parental strain was used for approval our suggestion. The recombinant cells, stored in dried state, as well as living yeast cells were tested for chromate-reducing activity in vitro in the presence of l-lactate (as an electron donor for chromate reduction) and different low molecular weight, redox-active mediators facilitating electron transfer from the reduced form of the enzyme to chromate (as a final electron acceptor): dichlorophenolindophenol (DCPIP), Methylene blue, Meldola blue, and Nile blue. It was shown that the highest chromate-reducing activity of the cells was achieved in the presence of DCPIP. The ability of chromate to catch electrons from the reduced flavocytochrome b(2) was confirmed using purified enzyme immobilized on the surface of a platinum electrode. The increasing concentration of Cr(VI) resulted in a decrease of enzyme-mediated current generated on the electrode during l-lactate oxidation. The shift and drop in amplitude of the peak in the cyclic voltammogram are indicative of Cr(VI)-dependent competition between reaction of chromate with reduced FC b(2) and direct electron transfer from the enzyme to the electrode surface. The application of the chromate-reducing ability of FC b(2)-over-producing recombinant cells of H. polymorpha toward chromate bioremediation and the construction of cells-based biosensor for chromate monitoring in the environment are discussed."
1235287,Campbell et al. 2011,"Sodium congener of the classical lithium methylchromate dimer: synthetic, X-ray crystallographic, and magnetic studies of Me8Cr2[Na(OEt2)]4","One of the milestone structures in the development of transition-metal complexes with metal-metal bonds of multiple bond order was the lithium methylchromate dimer Me(8)Cr(2)[Li(donor)](4) (donor = THF or Et(2)O). Using a simple salt metathesis reaction mixing this compound with sodium tert-butoxide, the sodium congener Me(8)Cr(2)[Na(OEt(2))](4) has been synthesized as a green crystalline compound and isolated in 51% yield. Its solid-state structure was determined by single-crystal X-ray diffraction. Exhibiting exact crystallographic C(4h) symmetry, this heavier alkali-metal chromate structure is also dimeric, formally comprising a (Me(8)Cr(4))(4-) tetranionic core with four peripheral Na(+) cations carrying supporting ether ligands. Its salient feature is the long Cr···Cr distance of 3.263(2) Å, which is remarkably elongated compared to that in the lithium THF-solvated congener [1.968(2) Å]. With respect to the methyl C atoms, the Cr coordination is distorted-square-planar. Each Na(+) interacts with four methyl C atoms, and there are also some short Na···H(C) contacts. Unlike for lithium chromate, no NMR spectroscopic data could be obtained for sodium chromate. The paramagnetic character of sodium chromate was confirmed by variable-temperature magnetization measurements, which indicated antiferromagnetic behavior.","Sodium congener of the classical lithium methylchromate dimer: synthetic, X-ray crystallographic, and magnetic studies of Me8Cr2[Na(OEt2)]4 Abs: One of the milestone structures in the development of transition-metal complexes with metal-metal bonds of multiple bond order was the lithium methylchromate dimer Me(8)Cr(2)[Li(donor)](4) (donor = THF or Et(2)O). Using a simple salt metathesis reaction mixing this compound with sodium tert-butoxide, the sodium congener Me(8)Cr(2)[Na(OEt(2))](4) has been synthesized as a green crystalline compound and isolated in 51% yield. Its solid-state structure was determined by single-crystal X-ray diffraction. Exhibiting exact crystallographic C(4h) symmetry, this heavier alkali-metal chromate structure is also dimeric, formally comprising a (Me(8)Cr(4))(4-) tetranionic core with four peripheral Na(+) cations carrying supporting ether ligands. Its salient feature is the long Cr···Cr distance of 3.263(2) Å, which is remarkably elongated compared to that in the lithium THF-solvated congener [1.968(2) Å]. With respect to the methyl C atoms, the Cr coordination is distorted-square-planar. Each Na(+) interacts with four methyl C atoms, and there are also some short Na···H(C) contacts. Unlike for lithium chromate, no NMR spectroscopic data could be obtained for sodium chromate. The paramagnetic character of sodium chromate was confirmed by variable-temperature magnetization measurements, which indicated antiferromagnetic behavior."
1235283,Langeroudi et al. 2011,Determination of free cyanide and zinc cyanide complex by capillary electrophoresis,"A capillary electrophoretic (CE) protocol was developed for the separation and quantification of free cyanide and zinc cyanide complex, two key species in gold cyanidation of zinc-bearing sulfidic ores. Several common carrier electrolytes were implemented in an indirect UV detection method. The effect of electric field strength, injection volume, concentration of electro-osmotic flow (EOF) modifier and UV-absorbing agent in background electrolyte (BGE) was examined while peak height, peak area and noise were considered for optimization. The best results were obtained using a BGE that contained 35 mM sodium chromate, 12 mM free cyanide and 0.45 mM hexamethonium bromide at pH 10.5. Free cyanide concentration was compared to that measured with the conventional silver nitrate titration method in solutions containing free cyanides and weak cyano-complexes. The developed CE protocol proved very robust in capturing the concentration of free cyanides (4% error) unlike the titration method which exhibited substantial sensitivity to the interfering weak cyano-complexes (38% error).","Determination of free cyanide and zinc cyanide complex by capillary electrophoresis Abs: A capillary electrophoretic (CE) protocol was developed for the separation and quantification of free cyanide and zinc cyanide complex, two key species in gold cyanidation of zinc-bearing sulfidic ores. Several common carrier electrolytes were implemented in an indirect UV detection method. The effect of electric field strength, injection volume, concentration of electro-osmotic flow (EOF) modifier and UV-absorbing agent in background electrolyte (BGE) was examined while peak height, peak area and noise were considered for optimization. The best results were obtained using a BGE that contained 35 mM sodium chromate, 12 mM free cyanide and 0.45 mM hexamethonium bromide at pH 10.5. Free cyanide concentration was compared to that measured with the conventional silver nitrate titration method in solutions containing free cyanides and weak cyano-complexes. The developed CE protocol proved very robust in capturing the concentration of free cyanides (4% error) unlike the titration method which exhibited substantial sensitivity to the interfering weak cyano-complexes (38% error)."
1235281,El-Yamani et al. 2011,Chromium-induced genotoxicity and interference in human lymphoblastoid cell (TK6) repair processes,"Two model chromium (Cr) compounds, one hexavalent (sodium chromate) and one trivalent (chromium chloride), were investigated in a human lymphoblastoid cell line (TK6) to increase our knowledge regarding Cr-induced genotoxicity mechanisms. Both selected compounds were genotoxic using the comet assay, although the percentage of DNA in tail obtained after treatment with Cr(VI) was significantly higher than that obtained with Cr(III), at the higher concentrations tested. To determine the nature of the induced damage, enzymes recognizing oxidized bases were used. Treatments with formamidopyrimidine (FPG) and endonuclease III (EndoIII) displayed a greater degree of DNA damage, indicating that the induction of oxidized bases accounts for an important proportion of the damage induced by Cr compounds. In addition, the kinetic repair studies showed that generated DNA damage is removed in approximately 8 h, with the damage induced by Cr(III) being removed/repaired more rapidly than damage produced by Cr(VI). To detect Cr interferences with the repair process, a post-treatment was applied after exposure to 2 Gy gamma radiation. Post-treatment significantly delayed the repair kinetics of DNA damage induced by radiation. This interference effect induced by Cr(VI) was more pronounced. In conclusion, evidence indicates that a high proportion of the Cr-induced DNA damage is correlated with oxidative damage, and that both Cr compounds interfere with repair mechanisms involved in repair of DNA damage induced by gamma radiation.","Chromium-induced genotoxicity and interference in human lymphoblastoid cell (TK6) repair processes Abs: Two model chromium (Cr) compounds, one hexavalent (sodium chromate) and one trivalent (chromium chloride), were investigated in a human lymphoblastoid cell line (TK6) to increase our knowledge regarding Cr-induced genotoxicity mechanisms. Both selected compounds were genotoxic using the comet assay, although the percentage of DNA in tail obtained after treatment with Cr(VI) was significantly higher than that obtained with Cr(III), at the higher concentrations tested. To determine the nature of the induced damage, enzymes recognizing oxidized bases were used. Treatments with formamidopyrimidine (FPG) and endonuclease III (EndoIII) displayed a greater degree of DNA damage, indicating that the induction of oxidized bases accounts for an important proportion of the damage induced by Cr compounds. In addition, the kinetic repair studies showed that generated DNA damage is removed in approximately 8 h, with the damage induced by Cr(III) being removed/repaired more rapidly than damage produced by Cr(VI). To detect Cr interferences with the repair process, a post-treatment was applied after exposure to 2 Gy gamma radiation. Post-treatment significantly delayed the repair kinetics of DNA damage induced by radiation. This interference effect induced by Cr(VI) was more pronounced. In conclusion, evidence indicates that a high proportion of the Cr-induced DNA damage is correlated with oxidative damage, and that both Cr compounds interfere with repair mechanisms involved in repair of DNA damage induced by gamma radiation."
1235277,Stocks et al. 2012,Has European Union legislation to reduce exposure to chromate in cement been effective in reducing the incidence of allergic contact dermatitis attributed to chromate in the UK?,"<strong>OBJECTIVE: </strong>Hexavalent chromate (chromate) in cement is a well-recognised cause of allergic contact dermatitis (ACD). Consequently in January 2005, following European Union legislation (EU Directive 2003/53/EC), the use or supply of cement containing &gt;2 ppm of chromate was prohibited in the UK (COSHH 2004). This analysis of work-related ill-health surveillance aims to evaluate the effectiveness of this legislation.<br /><br /><strong>METHOD: </strong>Changes in the incidence of work-related ACD cases returned to The Health and Occupation Reporting network by dermatologists were analysed taking in to account attribution to chromate and occupation.<br /><br /><strong>RESULTS: </strong>There was a significant decline in the incidence of both ACD attributed to chromate (incidence rate ratio 0.48, 95% CI 0.36 to 0.64) and ACD not-attributed chromate (0.76, 95% CI 0.69 to 0.85) between the time period preceding the EU legislation (2002-2004) and the postlegislation period (2005-2009). However, the decline in ACD attributed to chromate was significantly greater (p=0.006). This decline was further increased in workers potentially exposed to cement (incidence rate ratio 0.37, p=0.001). The majority of the decline in incidence occurred during 2005.<br /><br /><strong>CONCLUSION: </strong>The timing of this significant decline in the UK incidence of chromate attributed ACD, and the greater decline in workers potentially exposed to cement strongly suggests that the EU Directive2003/53/EC was successful in reducing exposure to chromate in cement in the UK.","Has European Union legislation to reduce exposure to chromate in cement been effective in reducing the incidence of allergic contact dermatitis attributed to chromate in the UK? Abs: <strong>OBJECTIVE: </strong>Hexavalent chromate (chromate) in cement is a well-recognised cause of allergic contact dermatitis (ACD). Consequently in January 2005, following European Union legislation (EU Directive 2003/53/EC), the use or supply of cement containing &gt;2 ppm of chromate was prohibited in the UK (COSHH 2004). This analysis of work-related ill-health surveillance aims to evaluate the effectiveness of this legislation.<br /><br /><strong>METHOD: </strong>Changes in the incidence of work-related ACD cases returned to The Health and Occupation Reporting network by dermatologists were analysed taking in to account attribution to chromate and occupation.<br /><br /><strong>RESULTS: </strong>There was a significant decline in the incidence of both ACD attributed to chromate (incidence rate ratio 0.48, 95% CI 0.36 to 0.64) and ACD not-attributed chromate (0.76, 95% CI 0.69 to 0.85) between the time period preceding the EU legislation (2002-2004) and the postlegislation period (2005-2009). However, the decline in ACD attributed to chromate was significantly greater (p=0.006). This decline was further increased in workers potentially exposed to cement (incidence rate ratio 0.37, p=0.001). The majority of the decline in incidence occurred during 2005.<br /><br /><strong>CONCLUSION: </strong>The timing of this significant decline in the UK incidence of chromate attributed ACD, and the greater decline in workers potentially exposed to cement strongly suggests that the EU Directive2003/53/EC was successful in reducing exposure to chromate in cement in the UK."
1235269,Wienecke et al. 2012,Pro-inflammatory effector Th cells transmigrate through anti-inflammatory environments into the murine fetus,"The presence of maternal DNA or even maternal cells within the offspring (microchimerism) has been reported for many fetal tissues, including the liver, heart, and spleen. Microchimerism is believed to be involved in the pathogenesis of autoimmune diseases; however, the cellular origin of this phenomenon remains unknown. Here, we determined whether differentiated T lymphocytes could transmigrate through the immunosuppressive environment of the placenta to reach the fetus. In vitro-differentiated effector/memory Th1 and Th17 cells from OVA???????-specific TCR(tg) T cells of OT-II mice were adoptively transferred (i.v.) into the tail veins of pregnant Ly5.1 mice at d15 and d19 of gestation. Mice were then sacrificed 40 h after adoptive cell transfer. Using radioactive labeling of T cells with sodium chromate [Cr?¹] prior to adoptive transfer, we observed that homing of pro-inflammatory Th cells was equally efficient in both pregnant and non-pregnant mice. Transmigration of Th1- and Th17-like cells through the highly immunosuppressive environment of the placenta into the fetus was significantly enhanced in experimental mice compared to control mice (P &lt; 0.0001). In addition, a substantial amount of effector Th cells accumulated in the placenta. Finally, we found that treatment with Pertussis Toxin resulted in a 3-fold increase in the transmigration of effector Th17 cells into the fetus (P &lt; 0.0001). When pro-inflammatory Th1-or Th17-like cells were injected into syngeneic mothers, almost all of the fetuses analyzed exhibited radioactivity, suggesting that transmigration of effector T cells occurs frequently. Our results suggest the possibility of novel roles for these maternal effector cells in the pathogenesis or reduction of disease.","Pro-inflammatory effector Th cells transmigrate through anti-inflammatory environments into the murine fetus Abs: The presence of maternal DNA or even maternal cells within the offspring (microchimerism) has been reported for many fetal tissues, including the liver, heart, and spleen. Microchimerism is believed to be involved in the pathogenesis of autoimmune diseases; however, the cellular origin of this phenomenon remains unknown. Here, we determined whether differentiated T lymphocytes could transmigrate through the immunosuppressive environment of the placenta to reach the fetus. In vitro-differentiated effector/memory Th1 and Th17 cells from OVA???????-specific TCR(tg) T cells of OT-II mice were adoptively transferred (i.v.) into the tail veins of pregnant Ly5.1 mice at d15 and d19 of gestation. Mice were then sacrificed 40 h after adoptive cell transfer. Using radioactive labeling of T cells with sodium chromate [Cr?¹] prior to adoptive transfer, we observed that homing of pro-inflammatory Th cells was equally efficient in both pregnant and non-pregnant mice. Transmigration of Th1- and Th17-like cells through the highly immunosuppressive environment of the placenta into the fetus was significantly enhanced in experimental mice compared to control mice (P &lt; 0.0001). In addition, a substantial amount of effector Th cells accumulated in the placenta. Finally, we found that treatment with Pertussis Toxin resulted in a 3-fold increase in the transmigration of effector Th17 cells into the fetus (P &lt; 0.0001). When pro-inflammatory Th1-or Th17-like cells were injected into syngeneic mothers, almost all of the fetuses analyzed exhibited radioactivity, suggesting that transmigration of effector T cells occurs frequently. Our results suggest the possibility of novel roles for these maternal effector cells in the pathogenesis or reduction of disease."
1235266,Xiaohua et al. 2012,Evaluation of the correlation between genetic damage and occupational chromate exposure through BNMN frequencies,"<strong>OBJECTIVE: </strong>To evaluate the correlation between chromate exposure and binucleated cells with micronuclei (BNMN) frequencies in chromate production workers and explore the ideal biomarker to detect early DNA damage.<br /><br /><strong>METHODS: </strong>There are 79 workers and 112 peasants in this study. Chromium concentrations in the air (CrA), blood (CrB), and urine (CrU) were detected. BNMN frequencies were also counted.<br /><br /><strong>RESULTS: </strong>The CrA, CrB, CrU, and BNMN frequencies of the exposure group were higher than those of the control group; BNMN frequencies were positively correlated with CrB and CrU; natural logarithm (Ln) BNMN was regressed on CrB, CrU, and CrA by linear models.<br /><br /><strong>CONCLUSIONS: </strong>The increases in CrB, CrU, and BNMN frequencies caused by lower CrA level suggest BNMN frequencies could be used to detect early DNA damage in the chromate production health surveillance.","Evaluation of the correlation between genetic damage and occupational chromate exposure through BNMN frequencies Abs: <strong>OBJECTIVE: </strong>To evaluate the correlation between chromate exposure and binucleated cells with micronuclei (BNMN) frequencies in chromate production workers and explore the ideal biomarker to detect early DNA damage.<br /><br /><strong>METHODS: </strong>There are 79 workers and 112 peasants in this study. Chromium concentrations in the air (CrA), blood (CrB), and urine (CrU) were detected. BNMN frequencies were also counted.<br /><br /><strong>RESULTS: </strong>The CrA, CrB, CrU, and BNMN frequencies of the exposure group were higher than those of the control group; BNMN frequencies were positively correlated with CrB and CrU; natural logarithm (Ln) BNMN was regressed on CrB, CrU, and CrA by linear models.<br /><br /><strong>CONCLUSIONS: </strong>The increases in CrB, CrU, and BNMN frequencies caused by lower CrA level suggest BNMN frequencies could be used to detect early DNA damage in the chromate production health surveillance."
1235265,Stern 2012,Assessing the threshold for the duodenal GSH/GSSG ratio in the mouse associated with sodium dichromate dihydrate ingestion reported by Thompson et al. (2011),,Assessing the threshold for the duodenal GSH/GSSG ratio in the mouse associated with sodium dichromate dihydrate ingestion reported by Thompson et al. (2011) Abs: 
1235262,Austin and  Eisenbrey 1911,EXPERIMENTAL ACUTE NEPHRITIS: THE ELIMINATION OF NITROGEN AND CHLORIDES AS COMPARED WITH THAT OF PHENOLSULPHONEPHTHALEIN,"1. Uranium and cantharidin, in the smallest doses capable of producing a distinct nephritis, tend to increase the elimination of nitrogen, probably by stimulating tissue katabolism. 2. Uranium, cantharidin, and potassium chromate, in larger doses, impair the power of the kidney to eliminate nitrogen; but this may not be evident unless the animal is on a high nitrogen diet, and the impairment, when due to potassium chromate, may not persist more than a day. 3. Small doses of uranium and of cantharidin cause a transient increase of chloride elimination which corresponds in a general way to the excess of diuresis. 4. Large doses of uranium and of chromate cause a fall, usually transient, in the chloride elimination. The chloride elimination may, however, be diminished forty per cent. for twenty-four hours without evidences of intoxication (vomiting). 5. The anatomic appearance of the kidney varies somewhat with the poison used and greatly with the period of survival after administration of the poison, but bears no definite relation to the nitrogen, chloride, or phenolsulphonephthalein elimination; marked anatomic alteration is compatible with normal elimination of all these substances and with freedom from symptoms of intoxication (vomiting). 6. The decrease in the elimination of phenolsulphonephthalein, which occurs in uranium, chromate, and cantharidin nephritides, and which, in a general way, is proportional to the dose of the poison, bears no constant relation to the changes in the nitrogen or chloride elimination. 7. A marked decrease in the elimination of the phenolsulphonephthalein occurs synchronously, as a rule, with the onset of the symptoms of intoxication (vomiting), and therefore the phenolsulphonephthalein test would seem to be a better indicator of the ability of the kidney to eliminate the toxic substance responsible for the symptoms of renal insufficiency than are either the anatomic changes or the elimination of total nitrogen or of chlorides.","EXPERIMENTAL ACUTE NEPHRITIS: THE ELIMINATION OF NITROGEN AND CHLORIDES AS COMPARED WITH THAT OF PHENOLSULPHONEPHTHALEIN Abs: 1. Uranium and cantharidin, in the smallest doses capable of producing a distinct nephritis, tend to increase the elimination of nitrogen, probably by stimulating tissue katabolism. 2. Uranium, cantharidin, and potassium chromate, in larger doses, impair the power of the kidney to eliminate nitrogen; but this may not be evident unless the animal is on a high nitrogen diet, and the impairment, when due to potassium chromate, may not persist more than a day. 3. Small doses of uranium and of cantharidin cause a transient increase of chloride elimination which corresponds in a general way to the excess of diuresis. 4. Large doses of uranium and of chromate cause a fall, usually transient, in the chloride elimination. The chloride elimination may, however, be diminished forty per cent. for twenty-four hours without evidences of intoxication (vomiting). 5. The anatomic appearance of the kidney varies somewhat with the poison used and greatly with the period of survival after administration of the poison, but bears no definite relation to the nitrogen, chloride, or phenolsulphonephthalein elimination; marked anatomic alteration is compatible with normal elimination of all these substances and with freedom from symptoms of intoxication (vomiting). 6. The decrease in the elimination of phenolsulphonephthalein, which occurs in uranium, chromate, and cantharidin nephritides, and which, in a general way, is proportional to the dose of the poison, bears no constant relation to the changes in the nitrogen or chloride elimination. 7. A marked decrease in the elimination of the phenolsulphonephthalein occurs synchronously, as a rule, with the onset of the symptoms of intoxication (vomiting), and therefore the phenolsulphonephthalein test would seem to be a better indicator of the ability of the kidney to eliminate the toxic substance responsible for the symptoms of renal insufficiency than are either the anatomic changes or the elimination of total nitrogen or of chlorides."
1235261,Ghoreyeb 1913,A STUDY OF THE MECHANICAL OBSTRUCTION TO THE CIRCULATION OF THE KIDNEY PRODUCED BY EXPERIMENTAL ACUTE TOXIC NEPHROPATHY,"1. Rabbits may have spontaneous nephropathy and show no casts or albumen in the urine. 2. If we leave out of consideration rabbits 17, 18, 19, and 20, which were perfused with Adler's solution, and rabbits 8, 9, 17, 18, and 28, which were injected subcutaneously with potassium chromate, rabbits 49 and 73 show that spontaneous nephropathy offers some impediment to the perfusing serum.","A STUDY OF THE MECHANICAL OBSTRUCTION TO THE CIRCULATION OF THE KIDNEY PRODUCED BY EXPERIMENTAL ACUTE TOXIC NEPHROPATHY Abs: 1. Rabbits may have spontaneous nephropathy and show no casts or albumen in the urine. 2. If we leave out of consideration rabbits 17, 18, 19, and 20, which were perfused with Adler's solution, and rabbits 8, 9, 17, 18, and 28, which were injected subcutaneously with potassium chromate, rabbits 49 and 73 show that spontaneous nephropathy offers some impediment to the perfusing serum."
1235260,Opie and  Alford 1915,"THE INFLUENCE OF DIET UPON NECROSIS CAUSED BY HEPATIC AND RENAL POISONS : PART II. DIET AND THE NEPHRITIS CAUSED BY POTASSIUM CHROMATE, URANIUM NITRATE, OR CHLOROFORM","Diet exerts a profound influence upon the toxicity (tested in the omnivorous white rat) of certain substances, namely, chloroform, phosphorus, potassium chromate, and uranium nitrate, which cause necrosis of the parenchymatous cells of the liver or of the kidney. Susceptibility to intoxication with all of these substances is less after a diet rich in carbohydrate than after a diet consisting of meat. Carbohydrates protect the parenchymatous cells of the liver or of the kidneys from necrosis caused by any one of these substances. Chloroform is much more toxic to animals which have received a diet consisting in great part of fat than to those which have received meat. When fat is fed to the white rat fatty infiltration occurs in the centers of the hepatic lobules and in the loops of Henle of the kidney. The necrosis caused by chloroform has the same location. The solubility of chloroform in fat determines the increased susceptibility of animals which have received fat and stored it in the parenchymatous cells of the liver and kidney. Susceptibility to intoxication with phosphorus which causes fatty degeneration and necrosis of the liver is not increased by a diet of fat. Necrosis caused by phosphorus occurs in the periphery of the hepatic lobule and exhibits maximum intensity in animals which have received meat. Susceptibility to intoxication with potassium chromate which causes nephritis with necrosis of the convoluted tubules of the kidney is not greater after a diet of fat than after a diet of meat. Susceptibility to intoxication with uranium nitrate which causes nephritis with advanced necrosis of renal tubules is increased by a diet of fat. The loops of Henle, in which fat is abundant after a diet of fat, are the chief site of necrosis.","THE INFLUENCE OF DIET UPON NECROSIS CAUSED BY HEPATIC AND RENAL POISONS : PART II. DIET AND THE NEPHRITIS CAUSED BY POTASSIUM CHROMATE, URANIUM NITRATE, OR CHLOROFORM Abs: Diet exerts a profound influence upon the toxicity (tested in the omnivorous white rat) of certain substances, namely, chloroform, phosphorus, potassium chromate, and uranium nitrate, which cause necrosis of the parenchymatous cells of the liver or of the kidney. Susceptibility to intoxication with all of these substances is less after a diet rich in carbohydrate than after a diet consisting of meat. Carbohydrates protect the parenchymatous cells of the liver or of the kidneys from necrosis caused by any one of these substances. Chloroform is much more toxic to animals which have received a diet consisting in great part of fat than to those which have received meat. When fat is fed to the white rat fatty infiltration occurs in the centers of the hepatic lobules and in the loops of Henle of the kidney. The necrosis caused by chloroform has the same location. The solubility of chloroform in fat determines the increased susceptibility of animals which have received fat and stored it in the parenchymatous cells of the liver and kidney. Susceptibility to intoxication with phosphorus which causes fatty degeneration and necrosis of the liver is not increased by a diet of fat. Necrosis caused by phosphorus occurs in the periphery of the hepatic lobule and exhibits maximum intensity in animals which have received meat. Susceptibility to intoxication with potassium chromate which causes nephritis with necrosis of the convoluted tubules of the kidney is not greater after a diet of fat than after a diet of meat. Susceptibility to intoxication with uranium nitrate which causes nephritis with advanced necrosis of renal tubules is increased by a diet of fat. The loops of Henle, in which fat is abundant after a diet of fat, are the chief site of necrosis."
1235255,May and  Kolthoff 1948,Studies on the aging of precipitates and coprecipitation; the solubility of lead chromate as a function of the particle size,,Studies on the aging of precipitates and coprecipitation; the solubility of lead chromate as a function of the particle size Abs: 
1235253,Harrold and  Meek 1949,Solubility and the relative toxicity of lead chromate,,Solubility and the relative toxicity of lead chromate Abs: 
1235251,Opie 1950,THE EFFECT OF INJURY BY TOXIC AGENTS UPON OSMOTIC PRESSURE MAINTAINED BY CELLS OF LIVER AND OF KIDNEY,"As shown in a previous paper the cells of the liver and of the kidney maintain an osmotic pressure approximately twice that of blood and of erythrocytes, exceeding this slightly in the case of liver and being slightly less in that of kidney. When liver cells are injured by chloroform or by carbon tetrachloride the osmotic pressure they maintain falls to the level of the medium that surrounds them but is promptly restored when recovery from the injury, with some regeneration of liver cells, occurs. When nephrosis is caused by potassium chromate or by chloroform the osmotic pressure maintained by parenchymatous cells of the renal cortex falls to that of the medium about them but returns to its normal level with recovery from the injury.","THE EFFECT OF INJURY BY TOXIC AGENTS UPON OSMOTIC PRESSURE MAINTAINED BY CELLS OF LIVER AND OF KIDNEY Abs: As shown in a previous paper the cells of the liver and of the kidney maintain an osmotic pressure approximately twice that of blood and of erythrocytes, exceeding this slightly in the case of liver and being slightly less in that of kidney. When liver cells are injured by chloroform or by carbon tetrachloride the osmotic pressure they maintain falls to the level of the medium that surrounds them but is promptly restored when recovery from the injury, with some regeneration of liver cells, occurs. When nephrosis is caused by potassium chromate or by chloroform the osmotic pressure maintained by parenchymatous cells of the renal cortex falls to that of the medium about them but returns to its normal level with recovery from the injury."
1235248,Dadlez and  Stolzman 1951,Oxidation of methyl alcohol in a mixture of potassium dichromate and sulphuric acid at 60 degrees C,,Oxidation of methyl alcohol in a mixture of potassium dichromate and sulphuric acid at 60 degrees C Abs: 
1235236,Hartogensis and  Zielhuis 1962,Health standards for lead chromate dust,"The toxicity of lead-chromate (7758976) was studied in male employees of three paint manufacturing companies. A total of 182 male workers who were not clinically ill was examined. Among this group, 26 workers were exclusively exposed to lead-chromate and were used as the subjects for the study. They were given a medical examination, which included a medical history, physical, and a laboratory investigation for hemoglobin, the number of basophil punctate erythrocytes, and concentration of coproporphyrins. Airborne concentrations of lead (7439921) and chromium (7440473) at the workplace were also determined. At factory 1, there was no correlation between lead and chromium concentrations in the air. In factories 2 and 3, there was good correlation indicating the presence of lead-chromate. Workers in factories 2 and 3 were classified into three groups based on their degree of exposure. Seven workers had exposures generally less than 0.1 milligram of lead per cubic meter (mg/m3); five workers had lead exposures greater than 0.2mg/m3. There was a consistent decrease in hemoglobin and a consistent increase in coproporphyrinuria and basophilia with increasing exposure to lead-chromate dust. The authors conclude that chronic exposure to lead-chromate at concentrations greater than 0.2mg/m3 can cause significant decreases in circulating hemoglobin among paint workers.","Health standards for lead chromate dust Abs: The toxicity of lead-chromate (7758976) was studied in male employees of three paint manufacturing companies. A total of 182 male workers who were not clinically ill was examined. Among this group, 26 workers were exclusively exposed to lead-chromate and were used as the subjects for the study. They were given a medical examination, which included a medical history, physical, and a laboratory investigation for hemoglobin, the number of basophil punctate erythrocytes, and concentration of coproporphyrins. Airborne concentrations of lead (7439921) and chromium (7440473) at the workplace were also determined. At factory 1, there was no correlation between lead and chromium concentrations in the air. In factories 2 and 3, there was good correlation indicating the presence of lead-chromate. Workers in factories 2 and 3 were classified into three groups based on their degree of exposure. Seven workers had exposures generally less than 0.1 milligram of lead per cubic meter (mg/m3); five workers had lead exposures greater than 0.2mg/m3. There was a consistent decrease in hemoglobin and a consistent increase in coproporphyrinuria and basophilia with increasing exposure to lead-chromate dust. The authors conclude that chronic exposure to lead-chromate at concentrations greater than 0.2mg/m3 can cause significant decreases in circulating hemoglobin among paint workers."
1235234,Pszonicki 1966,Precise titrimetric determination of uranium in high-purity uranium compounds,A procedure has been developed for the very precise determination of uranium in high-purity uranium compounds. Uranium(VI) is reduced in a strong hydrochloric acid solution with aluminium in the presence of cadmium ions to uranium(III). It is oxidised to uranium(IV) in the presence of excess orthophosphoric acid and then quantitatively oxidised to uranium(VI) with potassium dichromate using a potentiometric end-point detection. The coefficient of variation based on 20 analyses is -/+ 0.003%.,Precise titrimetric determination of uranium in high-purity uranium compounds Abs: A procedure has been developed for the very precise determination of uranium in high-purity uranium compounds. Uranium(VI) is reduced in a strong hydrochloric acid solution with aluminium in the presence of cadmium ions to uranium(III). It is oxidised to uranium(IV) in the presence of excess orthophosphoric acid and then quantitatively oxidised to uranium(VI) with potassium dichromate using a potentiometric end-point detection. The coefficient of variation based on 20 analyses is -/+ 0.003%.
1235233,Drummond and  Grant 1966,"Potentiometric determination of plutonium by argentic oxidation, ferrous reduction and dichromate titration","A simple and rapid method is described for the routine determination of plutonium with a coefficient of variation of better than 0.2%. It is directly applicable to nitrate solutions containing a large amount of uranium; moderate amounts of iron, molybdenum, fluoride and phosphate do not interfere. Chromium, cerium and manganese interfere quantitatively, and the procedure may also prove convenient for the determination of these elements. The plutonium is oxidised to the sexivalent state with argentic oxide in nitric acid solution, and the excess of oxidant is destroyed by reaction with sulphamic acid. A weighed small excess of iron(II) solution is then added, and the excess is titrated potentiometrically with standard potassium dichromate solution using polarised gold indicator electrodes. The whole determination is performed in one vessel at room temperature, and takes about 20 min.","Potentiometric determination of plutonium by argentic oxidation, ferrous reduction and dichromate titration Abs: A simple and rapid method is described for the routine determination of plutonium with a coefficient of variation of better than 0.2%. It is directly applicable to nitrate solutions containing a large amount of uranium; moderate amounts of iron, molybdenum, fluoride and phosphate do not interfere. Chromium, cerium and manganese interfere quantitatively, and the procedure may also prove convenient for the determination of these elements. The plutonium is oxidised to the sexivalent state with argentic oxide in nitric acid solution, and the excess of oxidant is destroyed by reaction with sulphamic acid. A weighed small excess of iron(II) solution is then added, and the excess is titrated potentiometrically with standard potassium dichromate solution using polarised gold indicator electrodes. The whole determination is performed in one vessel at room temperature, and takes about 20 min."
1235232,Rao and  Rao 1966,A new oxidimetric reagent: potassium dichromate in a strong phosphoric acid medium-VI Potentiometric titration of vanadium(III) alone and in mixture with vanadium(IV),"Vanadium(III) can be titrated at room temperature with potassium dichromate in an 8-12M phosphoric acid medium. Two potential breaks are observed in 12M phosphoric add with 0.2N potassium dichromate, the first corresponding to the oxidation of vanadium(III) to vanadium(IV) and the second to the oxidation of vanadium(IV) to vanadium(V). In titrations with 0.05N dichromate only the first break in potential is clearly observed. The method has been extended to the titration of mixtures of vanadium(III) and vanadium(IV). Conditions have also been found for the visual titration of vanadium(III) using ferroln or barium diphenylamine sulphonate as indicator.","A new oxidimetric reagent: potassium dichromate in a strong phosphoric acid medium-VI Potentiometric titration of vanadium(III) alone and in mixture with vanadium(IV) Abs: Vanadium(III) can be titrated at room temperature with potassium dichromate in an 8-12M phosphoric acid medium. Two potential breaks are observed in 12M phosphoric add with 0.2N potassium dichromate, the first corresponding to the oxidation of vanadium(III) to vanadium(IV) and the second to the oxidation of vanadium(IV) to vanadium(V). In titrations with 0.05N dichromate only the first break in potential is clearly observed. The method has been extended to the titration of mixtures of vanadium(III) and vanadium(IV). Conditions have also been found for the visual titration of vanadium(III) using ferroln or barium diphenylamine sulphonate as indicator."
1235230,Rao and  Krishna 1966,Stoichiometry of the reaction between iron(II) and chromium(VI),The suitability of potassium dichromate as a standard oxidant has been examined by comparing direct oxidation of iron(II) solutions with alternative back-titration procedures.,Stoichiometry of the reaction between iron(II) and chromium(VI) Abs: The suitability of potassium dichromate as a standard oxidant has been examined by comparing direct oxidation of iron(II) solutions with alternative back-titration procedures.
1235229,Rao and  Rao 1967,A new oxidimetric reagent: potassium dichromate in a strong phosphoric acid medium--VII. Photometric titration of vanadium(IV) and of cerium(III) alone and in mixtures with iroN(II),"Vanadium(IV) can be accurately titrated with potassium dichromate in media containing phosphoric acid of 3-12M concentration: the change in absorption of vanadium(IV) is followed in the region 660 mmicro using a red filter. It is more convenient to carry out the titration in 3M phosphoric acid because at higher concentrations chloride, nitrate, cerium(III) and manganese(II) may interfere. Photoelcetric titration is more convenient than potentiometric because the former can be made in a 3M phosphoric acid medium, whereas the latter is possible only in 12M phosphoric acid. The simultaneous differential photometric titration of iron(II) and vanadium(IV) is also possible. Conditions have been found for the photometric titration of cerium(III) and of cerium(III) plus iron(II). The titration is carried out (at 450 mmicro or with a blue filter) in about 10.5M phosphoric acid. Application of the method to a cerium mineral is considered.","A new oxidimetric reagent: potassium dichromate in a strong phosphoric acid medium--VII. Photometric titration of vanadium(IV) and of cerium(III) alone and in mixtures with iroN(II) Abs: Vanadium(IV) can be accurately titrated with potassium dichromate in media containing phosphoric acid of 3-12M concentration: the change in absorption of vanadium(IV) is followed in the region 660 mmicro using a red filter. It is more convenient to carry out the titration in 3M phosphoric acid because at higher concentrations chloride, nitrate, cerium(III) and manganese(II) may interfere. Photoelcetric titration is more convenient than potentiometric because the former can be made in a 3M phosphoric acid medium, whereas the latter is possible only in 12M phosphoric acid. The simultaneous differential photometric titration of iron(II) and vanadium(IV) is also possible. Conditions have been found for the photometric titration of cerium(III) and of cerium(III) plus iron(II). The titration is carried out (at 450 mmicro or with a blue filter) in about 10.5M phosphoric acid. Application of the method to a cerium mineral is considered."
1235228,Robinson et al. 1967,Rat-urine glycosidases and kidney damage,"1. The activities of beta-galactosidase, beta-glucosidase, beta-glucuronidase and N-acetyl, beta-glucosaminidase were estimated in normal and pathological rat urine, with 4-methylumbelliferyl glycosides as substrates. 2. Kidney damage induced by injections of uranium nitrate, mercuric chloride, potassium dichromate or 4-nitrophenylarsonic acid causes a marked increase in the urinary excretion of all four enzymes. 3. The rise in beta-glucosidase activity was associated with the appearance of a new urinary enzyme species, which was examined by starch-gel electrophoresis, DEAE-cellulose chromatography and filtration on Sephadex G-75 and G-200. 4. This enzyme appears to be identical with its counterpart in the kidney, and it is suggested that it arises in the urine as a result of renal tubular breakdown. 5. The other glycosidases examined also show some physical similarities to the corresponding enzymes of the rat kidney.","Rat-urine glycosidases and kidney damage Abs: 1. The activities of beta-galactosidase, beta-glucosidase, beta-glucuronidase and N-acetyl, beta-glucosaminidase were estimated in normal and pathological rat urine, with 4-methylumbelliferyl glycosides as substrates. 2. Kidney damage induced by injections of uranium nitrate, mercuric chloride, potassium dichromate or 4-nitrophenylarsonic acid causes a marked increase in the urinary excretion of all four enzymes. 3. The rise in beta-glucosidase activity was associated with the appearance of a new urinary enzyme species, which was examined by starch-gel electrophoresis, DEAE-cellulose chromatography and filtration on Sephadex G-75 and G-200. 4. This enzyme appears to be identical with its counterpart in the kidney, and it is suggested that it arises in the urine as a result of renal tubular breakdown. 5. The other glycosidases examined also show some physical similarities to the corresponding enzymes of the rat kidney."
1235225,Borneff et al. 1968,"Carcinogenic substances in water and soil. XXII. Mouse drinking study with 3,4-benzpyrene and potassium chromate",,"Carcinogenic substances in water and soil. XXII. Mouse drinking study with 3,4-benzpyrene and potassium chromate Abs: "
1235222,Hopwood 1969,Amino acids of the adrenal medulla and the effect of potassium dichromate oxidation on them,,Amino acids of the adrenal medulla and the effect of potassium dichromate oxidation on them Abs: 
1235220,Knoeck and  Diehl 1969,Coulometric assay of the primary standards potassium dichromate and ammonium hexanitratocerate,"The high-precision coulometric titration apparatus of Eckfeldt and Shaffer (Leeds &amp; Northrup Company) has been used for the precision assay of two primary standard materials for oxidation-reduction work. The purity found for NBS 136b Potassium Dichromate. 99.975 %, standard deviation 0.002 %, checks the earlier value of Marinenko and Taylor. Ammonium hexanitratocerate, if low in thorium, is also an excellent primary standard, two recent commercial preparations having purities of 99.972 and 99.984%, a higher standard deviation, 0.005 %, reflecting a minor difficulty in end-point detection caused by platinum oxide formation on the indicating electrodes.","Coulometric assay of the primary standards potassium dichromate and ammonium hexanitratocerate Abs: The high-precision coulometric titration apparatus of Eckfeldt and Shaffer (Leeds &amp; Northrup Company) has been used for the precision assay of two primary standard materials for oxidation-reduction work. The purity found for NBS 136b Potassium Dichromate. 99.975 %, standard deviation 0.002 %, checks the earlier value of Marinenko and Taylor. Ammonium hexanitratocerate, if low in thorium, is also an excellent primary standard, two recent commercial preparations having purities of 99.972 and 99.984%, a higher standard deviation, 0.005 %, reflecting a minor difficulty in end-point detection caused by platinum oxide formation on the indicating electrodes."
1235217,Lin 1969,Hologram formation in hardened dichromated gelatin films,"Hardened gelatin films sensitized with ammonium dichromate can be utilized to record high quality holograms. The maximum diffraction efficiency of the hologram approaches 90%. The light scattering from the hologram is so low that under ordinary light the hologram plate appears almost indistinguishable from a clear glass plate. Either a transmission or a reflection hologram can be recorded. Linear recording range of light amplitude is large. A practical method of preparing and processing the film is described, and the exposure characteristics are presented.","Hologram formation in hardened dichromated gelatin films Abs: Hardened gelatin films sensitized with ammonium dichromate can be utilized to record high quality holograms. The maximum diffraction efficiency of the hologram approaches 90%. The light scattering from the hologram is so low that under ordinary light the hologram plate appears almost indistinguishable from a clear glass plate. Either a transmission or a reflection hologram can be recorded. Linear recording range of light amplitude is large. A practical method of preparing and processing the film is described, and the exposure characteristics are presented."
1235215,Power et al. 1969,Lead poisoning in Gurkha soldiers in Hong Kong,"Investigation of an outbreak of lead-poisoning in 121 Gurkha soldiers showed that this was due to the contamination of chilli powder (cayenne pepper), a constituent of curry powder, with lead chromate. Comprehensive systems of food sampling are needed in developing communities.","Lead poisoning in Gurkha soldiers in Hong Kong Abs: Investigation of an outbreak of lead-poisoning in 121 Gurkha soldiers showed that this was due to the contamination of chilli powder (cayenne pepper), a constituent of curry powder, with lead chromate. Comprehensive systems of food sampling are needed in developing communities."
1235214,Skog and  Wahlberg 1969,Patch testing with potassium dichromate in different vehicles,,Patch testing with potassium dichromate in different vehicles Abs: 
1235210,Kaufman et al. 1970,Acute potassium dichromate poisoning. Treated by peritoneal dialysis,,Acute potassium dichromate poisoning. Treated by peritoneal dialysis Abs: 
1235209,Dubey et al. 1970,The Toxoplasma gondii oocyst from cat feces,"Coccidian oocysts resembling those of Isospora bigemina were excreted by cats fed Toxoplasma. In order to identify these oocysts with Toxoplasma infectivity a number of critical comparisons were made. The appearance of oocysts and Toxoplasma infectivity was simultaneous in the feces of 23 of 24 adult cats, 3-5 days after feeding of Toxoplasma cysts; in the feces of 4 out of 9 cats, 7-10 days after feeding of trophozoites; and in 8 out of 17 cats, 20-24 days after feeding of cat feces containing oocysts. Oocysts and infectivity were present in similar numbers, and they disappeared simultaneously from the feces of cats. Oocysts and infectivity were also observed simultaneously in the feces of 9 kittens, 1-2 days old, fed Toxoplasma cysts. Oocysts could not be separated from infectivity by filtration, by continuous particle electrophoresis, or by density gradient centrifugation. Excystation of oocysts was followed by an increase in titer of Toxoplasma infectivity. Unsporulated oocysts in fresh cat feces were noninfectious to mice, but oocyst sporulation was associated quantitatively with the development of infectivity at different temperatures and conditions of oxygenation. Maximum oocyst sporulation at 48 hr correlated with the development of maximum Toxoplasma infectivity. 1 and 2% sulfuric acid, and 2.5% potassium dichromate were found to be the best preservatives for sporulation of oocysts and for the development of Toxoplasma infectivity. Low sporulation rates in 0.1% formalin, 20% ethanol, and in water were associated with low infectivity in these reagents. Neither Toxoplasma infectivity nor oocysts developed in 0.3% formalin, 1% ammonium hydroxide, or 1% iodine in 20% ethanol. Oocysts, sporocysts, and sporozoites were stained specifically with Toxoplasma antibody in the indirect fluorescent antibody test. Typical coccidian stages, schizonts, and male and female gametocytes were found in the epithelium of the small intestine of kittens fed Toxoplasma cysts. The classification of T. gondii is discussed in relation to that of other isosporan coccidia of cats and dogs. The term &quot;Toxoplasma oocyst&quot; is introduced and Toxoplasma is classified in the family Toxoplasmidae of the suborder Eimeriina. The species Isospora bigemina is restricted to dogs, and I. cati to cats. I. felis and so-called I. rivolta from cats were noninfectious to dogs, and did not confer immunity to subsequent infection with I. canis and I. rivolta from dogs.","The Toxoplasma gondii oocyst from cat feces Abs: Coccidian oocysts resembling those of Isospora bigemina were excreted by cats fed Toxoplasma. In order to identify these oocysts with Toxoplasma infectivity a number of critical comparisons were made. The appearance of oocysts and Toxoplasma infectivity was simultaneous in the feces of 23 of 24 adult cats, 3-5 days after feeding of Toxoplasma cysts; in the feces of 4 out of 9 cats, 7-10 days after feeding of trophozoites; and in 8 out of 17 cats, 20-24 days after feeding of cat feces containing oocysts. Oocysts and infectivity were present in similar numbers, and they disappeared simultaneously from the feces of cats. Oocysts and infectivity were also observed simultaneously in the feces of 9 kittens, 1-2 days old, fed Toxoplasma cysts. Oocysts could not be separated from infectivity by filtration, by continuous particle electrophoresis, or by density gradient centrifugation. Excystation of oocysts was followed by an increase in titer of Toxoplasma infectivity. Unsporulated oocysts in fresh cat feces were noninfectious to mice, but oocyst sporulation was associated quantitatively with the development of infectivity at different temperatures and conditions of oxygenation. Maximum oocyst sporulation at 48 hr correlated with the development of maximum Toxoplasma infectivity. 1 and 2% sulfuric acid, and 2.5% potassium dichromate were found to be the best preservatives for sporulation of oocysts and for the development of Toxoplasma infectivity. Low sporulation rates in 0.1% formalin, 20% ethanol, and in water were associated with low infectivity in these reagents. Neither Toxoplasma infectivity nor oocysts developed in 0.3% formalin, 1% ammonium hydroxide, or 1% iodine in 20% ethanol. Oocysts, sporocysts, and sporozoites were stained specifically with Toxoplasma antibody in the indirect fluorescent antibody test. Typical coccidian stages, schizonts, and male and female gametocytes were found in the epithelium of the small intestine of kittens fed Toxoplasma cysts. The classification of T. gondii is discussed in relation to that of other isosporan coccidia of cats and dogs. The term &quot;Toxoplasma oocyst&quot; is introduced and Toxoplasma is classified in the family Toxoplasmidae of the suborder Eimeriina. The species Isospora bigemina is restricted to dogs, and I. cati to cats. I. felis and so-called I. rivolta from cats were noninfectious to dogs, and did not confer immunity to subsequent infection with I. canis and I. rivolta from dogs."
1235205,Johar et al. 1971,"New methods for the detection of carboxylic acid groups in organic compounds, with acriflavine","The dye acriflavine is used for the selective detection of the carboxylic acid group in organic compounds. Two simple, rapid, and reliable colour tests are reported; these are based on the development of a violet colour and a yellow to yellowish-brown precipitate when a carboxylic acid is treated with acriflavine/sodium nitrite and acriflavine/potassium chromate respectively. Other acidic compounds such as phenols, thiophenols, sulphinic acids, sulphonamides, and acid imides do not interfere. Sulphonic acids (with the exception of their amino derivatives) interfere with both the tests. Enols and salts of organic bases do not interfere in the former test, whereas they do interfere in the latter test. The probable nature of the reaction products in both the tests has been discussed. Based on the former reaction, a procedure is described for the selective detection of nitrite ion. The limit of detection is 25 mug of nitrite per ml. Only iodide interferes.","New methods for the detection of carboxylic acid groups in organic compounds, with acriflavine Abs: The dye acriflavine is used for the selective detection of the carboxylic acid group in organic compounds. Two simple, rapid, and reliable colour tests are reported; these are based on the development of a violet colour and a yellow to yellowish-brown precipitate when a carboxylic acid is treated with acriflavine/sodium nitrite and acriflavine/potassium chromate respectively. Other acidic compounds such as phenols, thiophenols, sulphinic acids, sulphonamides, and acid imides do not interfere. Sulphonic acids (with the exception of their amino derivatives) interfere with both the tests. Enols and salts of organic bases do not interfere in the former test, whereas they do interfere in the latter test. The probable nature of the reaction products in both the tests has been discussed. Based on the former reaction, a procedure is described for the selective detection of nitrite ion. The limit of detection is 25 mug of nitrite per ml. Only iodide interferes."
1235204,Kiba et al. 1972,Separation and determination of ruthenium by evolution with chromium(VI)-condensed phosphoric acid reagent,"Ruthenium in various chemical forms can be evolved as the tetroxide from insoluble matrix materials by heating the sample with chromium(VI)-condensed phosphoric acid reagent (abbreviated as Cr(VI)-CPA). Because of its excellent decomposing power for various solid samples, condensed phosphoric acid is very useful in the chemical analysis of various insoluble materials, and when an oxidizing agent such as potassium dichromate is added in the CPA medium, drastic oxidation proceeds on heating. This method is now extended to the separation of ruthenium from marine sediments. During the reaction with Cr(VI)-CPA ruthenium tetroxide is evolved and collected in an absorbent solution of 6M hydrochloric acid and ethanol (1:1), and the ruthenium is then determined spectrophotometrically with thiourea or radiometrically by counting the beta or gamma-activity. Osmium, which can be evolved as the tetroxide by the same treatment, can be eliminated beforehand by heating the sample with Ce(IV)-CPA, which removes osmium but not ruthenium. The successive distillations by means of Ce(IV)-CPA and Cr(VI)-CPA give satisfactory results for the separation between osmium and ruthenium. This method might be useful for the separation of ruthenium in geochemical or neutron-activation analysis.","Separation and determination of ruthenium by evolution with chromium(VI)-condensed phosphoric acid reagent Abs: Ruthenium in various chemical forms can be evolved as the tetroxide from insoluble matrix materials by heating the sample with chromium(VI)-condensed phosphoric acid reagent (abbreviated as Cr(VI)-CPA). Because of its excellent decomposing power for various solid samples, condensed phosphoric acid is very useful in the chemical analysis of various insoluble materials, and when an oxidizing agent such as potassium dichromate is added in the CPA medium, drastic oxidation proceeds on heating. This method is now extended to the separation of ruthenium from marine sediments. During the reaction with Cr(VI)-CPA ruthenium tetroxide is evolved and collected in an absorbent solution of 6M hydrochloric acid and ethanol (1:1), and the ruthenium is then determined spectrophotometrically with thiourea or radiometrically by counting the beta or gamma-activity. Osmium, which can be evolved as the tetroxide by the same treatment, can be eliminated beforehand by heating the sample with Ce(IV)-CPA, which removes osmium but not ruthenium. The successive distillations by means of Ce(IV)-CPA and Cr(VI)-CPA give satisfactory results for the separation between osmium and ruthenium. This method might be useful for the separation of ruthenium in geochemical or neutron-activation analysis."
1235203,Schwartz et al. 1972,Tamm-Horsfall mucoprotein: III. Potassium dichromate-induced renal tubular damage,"Renal tubular damage produced in rats by potassium dichromate results in a bimodal excretion of Tamm-Horsfall mucoprotein normally located in the epithelial cells of the ascending limb and distal convoluted tubule. The first peak occurs within 12 hours after dichromate administration. At this time no tubular epithelial structural changes can be demonstrated. However, by immunofluorescent staining, there is increased intraluminal mucoprotein. The second peak of excretion at 24 to 72 hours coincides with tubular necrosis and cast formation. These findings suggest that the monitoring of Tamm-Horsfall mucoprotein excretion may be useful in evaluating early or incipient renal tubular damage.","Tamm-Horsfall mucoprotein: III. Potassium dichromate-induced renal tubular damage Abs: Renal tubular damage produced in rats by potassium dichromate results in a bimodal excretion of Tamm-Horsfall mucoprotein normally located in the epithelial cells of the ascending limb and distal convoluted tubule. The first peak occurs within 12 hours after dichromate administration. At this time no tubular epithelial structural changes can be demonstrated. However, by immunofluorescent staining, there is increased intraluminal mucoprotein. The second peak of excretion at 24 to 72 hours coincides with tubular necrosis and cast formation. These findings suggest that the monitoring of Tamm-Horsfall mucoprotein excretion may be useful in evaluating early or incipient renal tubular damage."
1235200,Kiba and  Takeuchi 1973,"Thermometric titration in investigation of the formation of polyanions of molybdenum(VI), tungsten(VI), vanadium(V), and chromium (VI)-I: comparison of thermometric and potentiometric titration curves","A new twin-cell thermometric titrator has been devised and used for thermometric titration of solutions of sodium molybdate, sodium tungstate, sodium orthovanadate, ammonium metavanadate, and potassium chromate with perchloric acid. The thermometric titration curves were compared with corresponding pH-titration curves for elucidation of the reactions occurring in the titrations. Thermometric titrimetric methods have been developed for the determination of tungsten, vanadium and chromium.","Thermometric titration in investigation of the formation of polyanions of molybdenum(VI), tungsten(VI), vanadium(V), and chromium (VI)-I: comparison of thermometric and potentiometric titration curves Abs: A new twin-cell thermometric titrator has been devised and used for thermometric titration of solutions of sodium molybdate, sodium tungstate, sodium orthovanadate, ammonium metavanadate, and potassium chromate with perchloric acid. The thermometric titration curves were compared with corresponding pH-titration curves for elucidation of the reactions occurring in the titrations. Thermometric titrimetric methods have been developed for the determination of tungsten, vanadium and chromium."
1235197,Hirsch and  Pakuts 1974,Renal cortical slice uptake and runout of N-methylnicotinamide and p-aminohippurate after potassium dichromate treatment,"Administration of 40?mg/kg potassium dichromate to adult male rats produced a significant enhancement of N-methylnicotinamide (NMN) uptake by renal cortical slices when measured 24?h after a single subcutaneous injection. Incubation under nitrogen or in the presence of dinitrophenol reduced NMN accumulation by kidney slices from control and treated rats to the same level. The rate of NMN runout was slower in renal cortical slices from rats treated with 40?mg/kg potassium dichromate, while p-aminohippurate (PAH) runout was significantly greater than control.","Renal cortical slice uptake and runout of N-methylnicotinamide and p-aminohippurate after potassium dichromate treatment Abs: Administration of 40?mg/kg potassium dichromate to adult male rats produced a significant enhancement of N-methylnicotinamide (NMN) uptake by renal cortical slices when measured 24?h after a single subcutaneous injection. Incubation under nitrogen or in the presence of dinitrophenol reduced NMN accumulation by kidney slices from control and treated rats to the same level. The rate of NMN runout was slower in renal cortical slices from rats treated with 40?mg/kg potassium dichromate, while p-aminohippurate (PAH) runout was significantly greater than control."
1235195,Mirza et al. 1975,Leukocyte migration inhibition in nickel dermatitis,"Leukocyte migration inhibitory factor assay was employed as an in vitro diagnostic aid in nickel dermatitis, the second most common contact dermatitis in North America. 15 patch test-positive and 5 patch test-negative patients, all giving a past history suggestive of nickel dermatitis, were investigated. Significant inhibition of leukocyte migration in both groups of patients was obtained only with nickel sulfate-albumin conjugate and not with unconjugated nickel sulfate. Specificity of this system was tested by utilizing an unrelated metallic albumin complex, and no inhibition was found. When patch testing is equivocal or contraindicated, this in vitro technique may be a practical alternative.","Leukocyte migration inhibition in nickel dermatitis Abs: Leukocyte migration inhibitory factor assay was employed as an in vitro diagnostic aid in nickel dermatitis, the second most common contact dermatitis in North America. 15 patch test-positive and 5 patch test-negative patients, all giving a past history suggestive of nickel dermatitis, were investigated. Significant inhibition of leukocyte migration in both groups of patients was obtained only with nickel sulfate-albumin conjugate and not with unconjugated nickel sulfate. Specificity of this system was tested by utilizing an unrelated metallic albumin complex, and no inhibition was found. When patch testing is equivocal or contraindicated, this in vitro technique may be a practical alternative."
1235194,Wolman 1975,Oxidation of lipids and membranes I: in vitro formation of peroxidative lipid polymers,"Fluorescent polymers were obtained by oxidizing partly emulsified linolenic acid with different oxidants. The speed of formation of polymers differed for the various oxidants, and the difference was not a simple function of the oxidation potential. The speed of polymerization also depended on the nature of the emulsion. The presence of egg albumen in the emulsion enhanced polymer formation with all oxidants. When the oxidants used are arranged in the order of decreasing speed of polymer formation, the order is different in the presence of albumen from what it is in the absence of albumen. With different oxidation catalysts most antioxidants and amino acids tested enhanced polymerization. In oxidation with ferric ions, with K-dichromate, and without added oxidants the only antioxidants which delayed polymerization were &quot;inhibitors.&quot; &quot;Retarders&quot; enhanced polymerization. With KMnO4 slight delay was caused by some retarders. The findings indicate that not only oxidation catalysts, but also proteins, amino acids, and antioxidants enhance polymerization. The possibility is suggested that in animal cells lipid pigment formation might represent a mechanism for neutralizing free radicals.","Oxidation of lipids and membranes I: in vitro formation of peroxidative lipid polymers Abs: Fluorescent polymers were obtained by oxidizing partly emulsified linolenic acid with different oxidants. The speed of formation of polymers differed for the various oxidants, and the difference was not a simple function of the oxidation potential. The speed of polymerization also depended on the nature of the emulsion. The presence of egg albumen in the emulsion enhanced polymer formation with all oxidants. When the oxidants used are arranged in the order of decreasing speed of polymer formation, the order is different in the presence of albumen from what it is in the absence of albumen. With different oxidation catalysts most antioxidants and amino acids tested enhanced polymerization. In oxidation with ferric ions, with K-dichromate, and without added oxidants the only antioxidants which delayed polymerization were &quot;inhibitors.&quot; &quot;Retarders&quot; enhanced polymerization. With KMnO4 slight delay was caused by some retarders. The findings indicate that not only oxidation catalysts, but also proteins, amino acids, and antioxidants enhance polymerization. The possibility is suggested that in animal cells lipid pigment formation might represent a mechanism for neutralizing free radicals."
1235193,Ravnskov et al. 1975,Proteinuria in pigs with experimentally induced renal damage,"Proteinuria was studied experimentally in pigs with renal damage induced by maleic acid, potassium dichromate and by 5/6 nephrectomy. The methods used were: analysis of total protein, immunochemical quantitation of a porcine low molecular weight (alpha-PLMW) protein, agarose gel electrophoresis, and gel chromatography of concentrated urine samples. The urinary clearance of the alpha-PLMW protein in normal pigs was considerably higher than LMW protein clearance in normal man. No increase was seen after surgery. The induction of proximal tubular damage resulted in an increased excretion of, above all, high molecular weight proteins (greater than or equal to albumin) but also of low molecular weight proteins. The highest increase in alpha-PLMW clearance was seen immediately after 5/6 nephrectomy, and the increased alpha-PLMW excretion in pigs with proximal tubular dysfunction was better correlated to creatinine clearance than to the degree of phosphaturia or glucosuria. The results suggest different renal handling of plasma proteins in pigs and humans.","Proteinuria in pigs with experimentally induced renal damage Abs: Proteinuria was studied experimentally in pigs with renal damage induced by maleic acid, potassium dichromate and by 5/6 nephrectomy. The methods used were: analysis of total protein, immunochemical quantitation of a porcine low molecular weight (alpha-PLMW) protein, agarose gel electrophoresis, and gel chromatography of concentrated urine samples. The urinary clearance of the alpha-PLMW protein in normal pigs was considerably higher than LMW protein clearance in normal man. No increase was seen after surgery. The induction of proximal tubular damage resulted in an increased excretion of, above all, high molecular weight proteins (greater than or equal to albumin) but also of low molecular weight proteins. The highest increase in alpha-PLMW clearance was seen immediately after 5/6 nephrectomy, and the increased alpha-PLMW excretion in pigs with proximal tubular dysfunction was better correlated to creatinine clearance than to the degree of phosphaturia or glucosuria. The results suggest different renal handling of plasma proteins in pigs and humans."
1235192,Sagi et al. 1975,Dichromate titration of thallium(I),"The formal redox potentials of the thallium(III)-thallium(I) couple in different acids of varying strengths are reported. The minimum concentration of hydrochloric acid required for a direct titration of thallium(I) with potassium dichromate is 5M. Thallium(I) can be titrated directly with the primary standard oxidant, potassium dichromate, at room temperature, with ferroin as indicator, in 6M hydrochloric acid. Atmospheric oxygen must be excluded.","Dichromate titration of thallium(I) Abs: The formal redox potentials of the thallium(III)-thallium(I) couple in different acids of varying strengths are reported. The minimum concentration of hydrochloric acid required for a direct titration of thallium(I) with potassium dichromate is 5M. Thallium(I) can be titrated directly with the primary standard oxidant, potassium dichromate, at room temperature, with ferroin as indicator, in 6M hydrochloric acid. Atmospheric oxygen must be excluded."
1235190,Dikshitulu and  Satyanarayana 1975,Direct photometric titration of tellurium,A direct photometric titration method has been developed for the determination of tellurium. Tellurium(IV) is titrated with potassium dichromate in 2-6M nitric acid (or 1-4M perchloric acid) at 380-430 nm (blue-violet filter). Selenium(IV) does not interfere.,Direct photometric titration of tellurium Abs: A direct photometric titration method has been developed for the determination of tellurium. Tellurium(IV) is titrated with potassium dichromate in 2-6M nitric acid (or 1-4M perchloric acid) at 380-430 nm (blue-violet filter). Selenium(IV) does not interfere.
1235189,Hirsch and  Pakutis 1975,Enhancement of renal organic base accumulated by potassium dichromate,,Enhancement of renal organic base accumulated by potassium dichromate Abs: 
1235187,Berndt 1975,The effect of potassium dichromate on renal tubular transport processes,"Several studies have been conducted to examine the effects of potassium dichromate on the morphology of renal tissue, but relatively few studies have been done on the functional aspects of the renal damage. This study was designed to examine with in vitro techniques the effects of dichromate on a number of renal tubular transport processes. The accumulation of paraaminohippurate (PAH) and of tetraethylammonium chloride (TEA) by both rat and rabbit slices was inhibited by 10?4m potassium dichromate added to the bathing solution. On the other hand, the accumulation of the nonmetabolizable amino acid, alpha-aminoisobutyric acid (AIB), was only modestly reduced. In addition, the uptake of TEA was stimulated significantly by low concentrations (10?6m) of potassium dichromate. Although, in general, similar results were obtained using renal cortical slices taken from pretreated animals significant differences occurred. For example, at none of the doses tested (5–20 mg/kg) was the accumulation of PAH, TEA, or AIB stimulated. This was true whether the measurements were made as soon as 0.5 hr after administration of potassium dichromate or as long as 5 days after its administration. At an intermediate dose of potassium dichromate (10 mg/kg) the lactate-stimulated accumulation of PAH was depressed, but the control or nonsubstrate-stimulated accumulation was not affected. In addition to the effects on uptake of organic compounds, potassium dichromate, whether administered to the intact animal or added to the extra-cellular fluid compartment, caused a decrease in the intracellular concentration of potassium and an increase in the intracellular concentration of sodium. From a quantitative point of view, however, the effect of the nephrotoxin administered to the intact animal was always greater on tissue electrolytes than when the nephrotoxin was added in vitro.","The effect of potassium dichromate on renal tubular transport processes Abs: Several studies have been conducted to examine the effects of potassium dichromate on the morphology of renal tissue, but relatively few studies have been done on the functional aspects of the renal damage. This study was designed to examine with in vitro techniques the effects of dichromate on a number of renal tubular transport processes. The accumulation of paraaminohippurate (PAH) and of tetraethylammonium chloride (TEA) by both rat and rabbit slices was inhibited by 10?4m potassium dichromate added to the bathing solution. On the other hand, the accumulation of the nonmetabolizable amino acid, alpha-aminoisobutyric acid (AIB), was only modestly reduced. In addition, the uptake of TEA was stimulated significantly by low concentrations (10?6m) of potassium dichromate. Although, in general, similar results were obtained using renal cortical slices taken from pretreated animals significant differences occurred. For example, at none of the doses tested (5–20 mg/kg) was the accumulation of PAH, TEA, or AIB stimulated. This was true whether the measurements were made as soon as 0.5 hr after administration of potassium dichromate or as long as 5 days after its administration. At an intermediate dose of potassium dichromate (10 mg/kg) the lactate-stimulated accumulation of PAH was depressed, but the control or nonsubstrate-stimulated accumulation was not affected. In addition to the effects on uptake of organic compounds, potassium dichromate, whether administered to the intact animal or added to the extra-cellular fluid compartment, caused a decrease in the intracellular concentration of potassium and an increase in the intracellular concentration of sodium. From a quantitative point of view, however, the effect of the nephrotoxin administered to the intact animal was always greater on tissue electrolytes than when the nephrotoxin was added in vitro."
1235185,Black and  Furman 1975,Procedure for calibrating the Technicon Colorimeter I,"We describe a rapid method for calibrating the Technicon AutoAnalyzer colorimeter I. Test solutions of bromphenol blue are recommended for the calibration, in preference to solutions of potassium dichromate, based on considerations of the instrument's working range and of the stray light characteristics of the associated filters.","Procedure for calibrating the Technicon Colorimeter I Abs: We describe a rapid method for calibrating the Technicon AutoAnalyzer colorimeter I. Test solutions of bromphenol blue are recommended for the calibration, in preference to solutions of potassium dichromate, based on considerations of the instrument's working range and of the stray light characteristics of the associated filters."
1235180,Baruch 1975,Shoe dermatitis: a case report,,Shoe dermatitis: a case report Abs: 
1235179,Beeler and  Lancaster 1975,CAP survey to assess the extent of stray light problems in precision spectrophotometry,"When the absorbance at 240 nm. of a solution of sodium iodide was measured by 159 laboratories using narrow-band-pass spectrophotometers, 15% reported results that suggested a problem caused by stray light. The laboratories were also requested to measure the absorbance at 240 nm. of solutions of acid potassium dichromate and alkaline potassium chromate. The laboratories that had stray-light problems reported absorbance results that were skewed in distribution and showed low mean values and wide instrument-to-instrument variation. The laboratories without stray light problems reported results with less instrument-to-instrument variation, the results followed a symmetrical distribution, and the mean of the results provided an accurate estimate of the absorbance of the solutions.","CAP survey to assess the extent of stray light problems in precision spectrophotometry Abs: When the absorbance at 240 nm. of a solution of sodium iodide was measured by 159 laboratories using narrow-band-pass spectrophotometers, 15% reported results that suggested a problem caused by stray light. The laboratories were also requested to measure the absorbance at 240 nm. of solutions of acid potassium dichromate and alkaline potassium chromate. The laboratories that had stray-light problems reported absorbance results that were skewed in distribution and showed low mean values and wide instrument-to-instrument variation. The laboratories without stray light problems reported results with less instrument-to-instrument variation, the results followed a symmetrical distribution, and the mean of the results provided an accurate estimate of the absorbance of the solutions."
1235178,Huriez et al. 1975,Sensitivity to dichromate in a milk analysis laboratory,,Sensitivity to dichromate in a milk analysis laboratory Abs: 
1235176,Mascorro et al. 1975,A glutaraldehyde/potassium dichromate tracing method for the localization and preservation of abdominal extra-adrenal chromaffin tissues,"The present work introduces a method for the localization in situ of the abdominal paraganglia. After treating retroperitoneal tissue blocks with a near-neutral glutaraldehyde/potassium dichromate solution following routine glutaraldehyde perfusion, intra- and extraadrenal chromaffin tissues develop a pronounced brown color from the interaction of glutaraldehyde/potassium dichromate with amines. In this manner, visualization of the abdominal extra-adrenal chromaffin organs is enhanced at the same time that cellular ultrastructure is preserved. Subsequent examination of the dichromate-reacted tissues with the electron microscope confirms that they represent the amine-rich paraganglia. This method offers an effective alternative to extensive sampling of plastic-embedded blocks for localizing peripheral chromaffin tissue and has been used to define the exact distribution of abdominal paraganglia in the rabbit.","A glutaraldehyde/potassium dichromate tracing method for the localization and preservation of abdominal extra-adrenal chromaffin tissues Abs: The present work introduces a method for the localization in situ of the abdominal paraganglia. After treating retroperitoneal tissue blocks with a near-neutral glutaraldehyde/potassium dichromate solution following routine glutaraldehyde perfusion, intra- and extraadrenal chromaffin tissues develop a pronounced brown color from the interaction of glutaraldehyde/potassium dichromate with amines. In this manner, visualization of the abdominal extra-adrenal chromaffin organs is enhanced at the same time that cellular ultrastructure is preserved. Subsequent examination of the dichromate-reacted tissues with the electron microscope confirms that they represent the amine-rich paraganglia. This method offers an effective alternative to extensive sampling of plastic-embedded blocks for localizing peripheral chromaffin tissue and has been used to define the exact distribution of abdominal paraganglia in the rabbit."
1235175,Rogers and  Burrows 1975,Contact dermatitis to chrome in milk testers,,Contact dermatitis to chrome in milk testers Abs: 
1235172,Lever et al. 1975,Reserpine-induced catecholamine depletion from small cells in rat sympathetic ganglia,"Two reserpine dosage schedules were applied to Wistar rats (a) 5 mg/kg i.p. 6 hr before sacrifice and (b) 5 mg/kg i.p. at 36, 24 and 12 hr prior to sacrifice. Control animals were correspondingly sham-injected. The coeliac-mesenteric ganglion complex was removed and processed either for the Falck-Hillarp fluorescence histochemical technique or fixed in glutaraldehyde followed by 3.5% potassium dichromate for a chromaffin-type reaction. After a single reserpine injection there was a statistically significant (p less than 0.001) reduction in the percentage of 'chromaffin-positive' cells and a statistically significant (p less than 0.001) increase in the percentage of 'chromaffin-negative' cells compared with controls. No obvious reduction in fluorophore emission from small intensely fluorescent (SIF) cells was observed. After prolonged reserpinization (3 x 5 mg/kg) there was a highly significant reduction in the percentage of 'chromaffin-positive' small cells and also a significantly lower (by a factor of 2) level of fluorescent emission from SIF cells. The catecholamine-releasing potential of small cells is demonstrated by these results.","Reserpine-induced catecholamine depletion from small cells in rat sympathetic ganglia Abs: Two reserpine dosage schedules were applied to Wistar rats (a) 5 mg/kg i.p. 6 hr before sacrifice and (b) 5 mg/kg i.p. at 36, 24 and 12 hr prior to sacrifice. Control animals were correspondingly sham-injected. The coeliac-mesenteric ganglion complex was removed and processed either for the Falck-Hillarp fluorescence histochemical technique or fixed in glutaraldehyde followed by 3.5% potassium dichromate for a chromaffin-type reaction. After a single reserpine injection there was a statistically significant (p less than 0.001) reduction in the percentage of 'chromaffin-positive' cells and a statistically significant (p less than 0.001) increase in the percentage of 'chromaffin-negative' cells compared with controls. No obvious reduction in fluorophore emission from small intensely fluorescent (SIF) cells was observed. After prolonged reserpinization (3 x 5 mg/kg) there was a highly significant reduction in the percentage of 'chromaffin-positive' small cells and also a significantly lower (by a factor of 2) level of fluorescent emission from SIF cells. The catecholamine-releasing potential of small cells is demonstrated by these results."
1235167,Scheper et al. 1976,Effects of contact sensitization and delayed hypersensitivity reactions on immune responses to non-related antigens. Modulation of Immune responses,"Guinea pigs were immunized intracutaneously into the ears with sheep red blood cells (SRBC). Application of a sensitizing dose of the contact allergen dinitrochlorobenzene (DNCB) onto the same ears was shown to suppress or enhance the humoral response to SRBC depending on the time of application. When guinea pigs were sensitized to a contact allergen, application of a sensitizing dose of a non-related allergen on the same ears either had no effect or caused a clear enhancement of the development of delayed type hypersensitivity (DTH). Strongest enhancement was found when both sensitizations were performed on the same day. Further experiments on the effects of a concomitant DTH reaction elicited at the site of application of a contact allergen showed a strong potentiation of DTH when B-cell suppression was minimized by pretreatment with cyclophosphamide (CY). It was considered that CY-DTH-immunopotentiation might be a useful tool for achieving a higher level of sensitivity after epicutaneous sensitization.","Effects of contact sensitization and delayed hypersensitivity reactions on immune responses to non-related antigens. Modulation of Immune responses Abs: Guinea pigs were immunized intracutaneously into the ears with sheep red blood cells (SRBC). Application of a sensitizing dose of the contact allergen dinitrochlorobenzene (DNCB) onto the same ears was shown to suppress or enhance the humoral response to SRBC depending on the time of application. When guinea pigs were sensitized to a contact allergen, application of a sensitizing dose of a non-related allergen on the same ears either had no effect or caused a clear enhancement of the development of delayed type hypersensitivity (DTH). Strongest enhancement was found when both sensitizations were performed on the same day. Further experiments on the effects of a concomitant DTH reaction elicited at the site of application of a contact allergen showed a strong potentiation of DTH when B-cell suppression was minimized by pretreatment with cyclophosphamide (CY). It was considered that CY-DTH-immunopotentiation might be a useful tool for achieving a higher level of sensitivity after epicutaneous sensitization."
1235166,Cohen 1976,The role of carrier in sensitivity to chromium and cobalt,"Patients suffering from contact dermatitis caused by chromium sensitivity showed positive reactions to intradermal tests with chromium and cobalt chlorides. Patch tests to cobalt in unaffected and in healed eczematous skin areas gave negative results. A large number of chromium-sensitive patients also showed a positive intradermal test reaction to cobalt bound to human serum albumin and a negative reaction to cobalt bound to rabbit liver glycogen. It has been suggested that these positive reactions to cobalt are secondary sensitivities to cobalt, caused by cobalt-denaturated human serum albumin that is so similar to the denaturated product of chromium cations that the competent cells cannot distinguish between them.","The role of carrier in sensitivity to chromium and cobalt Abs: Patients suffering from contact dermatitis caused by chromium sensitivity showed positive reactions to intradermal tests with chromium and cobalt chlorides. Patch tests to cobalt in unaffected and in healed eczematous skin areas gave negative results. A large number of chromium-sensitive patients also showed a positive intradermal test reaction to cobalt bound to human serum albumin and a negative reaction to cobalt bound to rabbit liver glycogen. It has been suggested that these positive reactions to cobalt are secondary sensitivities to cobalt, caused by cobalt-denaturated human serum albumin that is so similar to the denaturated product of chromium cations that the competent cells cannot distinguish between them."
1235162,Lepine 1976,Results of routine office patch testing,"The results of patch testing over the past 18 months in a general dermatology clinic are presented and compared with the data recently reported by the North American Contact Dermatitis Group. Good correlation exists between the results of the two studies for all the reported allergens except nickel sulfate and potassium dichromate. The increased incidence of sensitivity to these allergens reported in our series probably reflects the tendency for all metal related contact dermatitis to be referred to our clinic, even though recognized as such by the referring physician. The 16.8% reactivity to a dye mix used in our screening kit, and not reported by others, proved most interesting. In the light of continuing reports of dye related allergic contact dermatitis, our experience prompts us to suggest that a dye mix of some sort should be evaluated in future large-scale studies of patch test screening kits.","Results of routine office patch testing Abs: The results of patch testing over the past 18 months in a general dermatology clinic are presented and compared with the data recently reported by the North American Contact Dermatitis Group. Good correlation exists between the results of the two studies for all the reported allergens except nickel sulfate and potassium dichromate. The increased incidence of sensitivity to these allergens reported in our series probably reflects the tendency for all metal related contact dermatitis to be referred to our clinic, even though recognized as such by the referring physician. The 16.8% reactivity to a dye mix used in our screening kit, and not reported by others, proved most interesting. In the light of continuing reports of dye related allergic contact dermatitis, our experience prompts us to suggest that a dye mix of some sort should be evaluated in future large-scale studies of patch test screening kits."
1235156,Bear and  Strode 1976,The determination of metallic iron in the presence of fayalite,"In a proposed new procedure the sample is treated with bromine, the excess of bromine removed, and the residue extracted with methanol. After filtration the filtrate is evaporated to remove methanol and the bromides are dissolved in hydrochloric acid for determination of metallic iron. The oxide residue from the filtration is fused in sodium peroxide and then dissolved in hydrochloric acid for the determination of iron present either as oxide or silicate. Iron in the hydrochloric acid solutions from the residue and filtrate is determined either by titration with standard potassium dichromate solution or by atomic-absorption spectrometry.","The determination of metallic iron in the presence of fayalite Abs: In a proposed new procedure the sample is treated with bromine, the excess of bromine removed, and the residue extracted with methanol. After filtration the filtrate is evaporated to remove methanol and the bromides are dissolved in hydrochloric acid for determination of metallic iron. The oxide residue from the filtration is fused in sodium peroxide and then dissolved in hydrochloric acid for the determination of iron present either as oxide or silicate. Iron in the hydrochloric acid solutions from the residue and filtrate is determined either by titration with standard potassium dichromate solution or by atomic-absorption spectrometry."
1235155,Hirsch 1976,Differential effects of nephrotoxic agents on renal transport and metabolism by use of in vitro techniques,"A number of studies by the author and other investigators are reviewed in which the in vitro kidney slice technique has been used to evaluate the nephrotoxicity of various compounds. The kidney slice technique can be used to determine the effect of prior drug treatment of laboratory animals on renal organic acid (p-aminohippurate) or organic base (N-methylnicotinamide) transport, on glucose synthesis, and on oxygen consumption by renal coritical slices. The nephrotoxic agents uranyl nitrate and potassium dichromate exert inhibitory effects on renal function, althouhg both agents enhance organic base transport at low doses and potassium dichromate enhances organic acid transport at moderate doses. Enhanced PAH transport has been found to be a sensitive indicator of gentamicin induced nephrotoxicity, while inhibition of other parameters has been reported. The tissue slice method is less effective in evaluation chronic nephrotoxicity such as that produced by lead. The inhibitory effect of mercurial diuretics has been shown to be due to the general depression of metabolic activity by mercury. The kidney slice technique has been found to be a sensitive indicator in the assessment of halogenated hydrocarbon-induced nephrotoxicity. Differential effects of compounds on in vitro organic acid and base trasport provides information about the transport of these compounds as well as about their nephrotoxicity. Although it is often desirable to perform in vivo tests or other in vitro renal function tests, the kidney slice technique has proved to be extremely useful in toxicological evaluations.","Differential effects of nephrotoxic agents on renal transport and metabolism by use of in vitro techniques Abs: A number of studies by the author and other investigators are reviewed in which the in vitro kidney slice technique has been used to evaluate the nephrotoxicity of various compounds. The kidney slice technique can be used to determine the effect of prior drug treatment of laboratory animals on renal organic acid (p-aminohippurate) or organic base (N-methylnicotinamide) transport, on glucose synthesis, and on oxygen consumption by renal coritical slices. The nephrotoxic agents uranyl nitrate and potassium dichromate exert inhibitory effects on renal function, althouhg both agents enhance organic base transport at low doses and potassium dichromate enhances organic acid transport at moderate doses. Enhanced PAH transport has been found to be a sensitive indicator of gentamicin induced nephrotoxicity, while inhibition of other parameters has been reported. The tissue slice method is less effective in evaluation chronic nephrotoxicity such as that produced by lead. The inhibitory effect of mercurial diuretics has been shown to be due to the general depression of metabolic activity by mercury. The kidney slice technique has been found to be a sensitive indicator in the assessment of halogenated hydrocarbon-induced nephrotoxicity. Differential effects of compounds on in vitro organic acid and base trasport provides information about the transport of these compounds as well as about their nephrotoxicity. Although it is often desirable to perform in vivo tests or other in vitro renal function tests, the kidney slice technique has proved to be extremely useful in toxicological evaluations."
1235154,Tsuda and  Kato 1976,Potassium dichromate-induced chromosome aberrations and its control with sodium sulfite in hamster embryonic cells in vitro,"HEEP COPYRIGHT: BIOL ABS. Addition of K2Cr2O7 to hamster embryonic cells resulted in consistent and drastic chromosomal aberrations at concentrations of 0.5, 0.2 and 0.1 mug/ml. The environmental contamination by this metal may cause serious problems to human health, including genetic hazards.","Potassium dichromate-induced chromosome aberrations and its control with sodium sulfite in hamster embryonic cells in vitro Abs: HEEP COPYRIGHT: BIOL ABS. Addition of K2Cr2O7 to hamster embryonic cells resulted in consistent and drastic chromosomal aberrations at concentrations of 0.5, 0.2 and 0.1 mug/ml. The environmental contamination by this metal may cause serious problems to human health, including genetic hazards."
1235153,Johnson et al. 1976,"Mevalonate metabolism: effect of K2Cr2O7, a renal tubular toxin",,"Mevalonate metabolism: effect of K2Cr2O7, a renal tubular toxin Abs: "
1235149,Blake and  Tobin 1976,The gas-liquid chromatograph and the electron capture detection in equine drug testing,"Three gas-liquid chromatographic (G.L.C.) procedures discussed have been designed around the four &quot;esses&quot; of detection tests--speed, sensitivity, simplicity, and specificity. These techniques are admirably applicable to the very low plasma drug levels encountered in blood testing under pre-race conditions. The methods are equally applicable to post-race testing procedures, where both blood and urine samples are tested. Drugs can only rarely be detected by the electron capture detector (E.C.D.) without a prior derivatization step, which conveys to the drug(s) high electron affinity. Because of broad applicability, two derivatizing agents, heptafluorobutyric (HFBA) and pentafluorpropionic (PFPA) anhydrides are employed. The three techniques, allowing broad coverage of various drug classes are: 1) direct derivatization of drugs to form strongly electron capturing amides and esters. 2) reductive fragmentation of drugs with lithium aluminum hydride to form alcohols, with conversion to ester derivatives. 3) oxidative fragmentation of drugs with potassium dichromate to form derivatizable groups, followed by direct derivatization.","The gas-liquid chromatograph and the electron capture detection in equine drug testing Abs: Three gas-liquid chromatographic (G.L.C.) procedures discussed have been designed around the four &quot;esses&quot; of detection tests--speed, sensitivity, simplicity, and specificity. These techniques are admirably applicable to the very low plasma drug levels encountered in blood testing under pre-race conditions. The methods are equally applicable to post-race testing procedures, where both blood and urine samples are tested. Drugs can only rarely be detected by the electron capture detector (E.C.D.) without a prior derivatization step, which conveys to the drug(s) high electron affinity. Because of broad applicability, two derivatizing agents, heptafluorobutyric (HFBA) and pentafluorpropionic (PFPA) anhydrides are employed. The three techniques, allowing broad coverage of various drug classes are: 1) direct derivatization of drugs to form strongly electron capturing amides and esters. 2) reductive fragmentation of drugs with lithium aluminum hydride to form alcohols, with conversion to ester derivatives. 3) oxidative fragmentation of drugs with potassium dichromate to form derivatizable groups, followed by direct derivatization."
1235148,Tranzer and  Richards 1976,Ultrastructural cytochemistry of biogenic amines in nervous tissue: methodologic improvements,"A new fixation method has been developed for localizing biogenic amines in nervous tissue. The method is a modification of the chromaffin reaction in which all fixation steps are buffered with mixtures of sodium chromate and potassium dichromate. In this way the fixation and cytochemical reaction are carried out almost simultaneously. Using the rat vas deferens as a model tissue, it was found that the preservation of electron dense (chromaffin) cores in the vesicles of adrenergic nerve terminals depended on several factors: a short primary fixation using low concentrations of aldehydes, the presence of the chromate/dichromate buffer during all fixation steps and, finally, a long incubation period in a slightly acidic (pH 6.0) solution of this buffer before postfixation in osmium tetroxide. Using this method it was possible to identify not only small and large dense-cored vesicles as storage sites for amines but also a tubular reticulum (neuronal endoplasmic reticulum), the latter especially in nerve terminals of mesenteric arteries and iris. Biogenic amines were also visualized in sympathetic ganglion cells and in the central nervous system e.g., supraependymal nerve terminals, tissues that up to now proved the most difficult in terms of amine localization. In all the tissues examined the cytochemical reaction was highly selective and present in well preserved tissue, which is a significant advance over previously available techniques. It therefore offers new opportunities for further studies on the role of biogenic amines as neurotransmitters.","Ultrastructural cytochemistry of biogenic amines in nervous tissue: methodologic improvements Abs: A new fixation method has been developed for localizing biogenic amines in nervous tissue. The method is a modification of the chromaffin reaction in which all fixation steps are buffered with mixtures of sodium chromate and potassium dichromate. In this way the fixation and cytochemical reaction are carried out almost simultaneously. Using the rat vas deferens as a model tissue, it was found that the preservation of electron dense (chromaffin) cores in the vesicles of adrenergic nerve terminals depended on several factors: a short primary fixation using low concentrations of aldehydes, the presence of the chromate/dichromate buffer during all fixation steps and, finally, a long incubation period in a slightly acidic (pH 6.0) solution of this buffer before postfixation in osmium tetroxide. Using this method it was possible to identify not only small and large dense-cored vesicles as storage sites for amines but also a tubular reticulum (neuronal endoplasmic reticulum), the latter especially in nerve terminals of mesenteric arteries and iris. Biogenic amines were also visualized in sympathetic ganglion cells and in the central nervous system e.g., supraependymal nerve terminals, tissues that up to now proved the most difficult in terms of amine localization. In all the tissues examined the cytochemical reaction was highly selective and present in well preserved tissue, which is a significant advance over previously available techniques. It therefore offers new opportunities for further studies on the role of biogenic amines as neurotransmitters."
1235147,Coupland et al. 1976,On the fixation of catecholamines including adrenaline in tissue sections,Following intravenous or intraperitoneal injections of 3H-l-dopa radioactivity in adrenal medullary chromaffin cells of the mouse has been followed by autoradiographic and radioisotopic assay methods. For autoradiographic purposes tissues were fixed in either phosphate buffered glutaraldehyde or in 1-5% potassium dichromate in glutaraldehyde pH 7-2. A high initial radioactivity is demonstrated by both autoradiography and radioisotopic assay. During the first hour dopamine is the predominant labelled amine. Between 1 and 4 hours after the injection noradrenaline is in highest concentration and from 1 to 24 hours labelled adrenaline appears and becomes the predominant labelled amine (about 70%) after 24 hours. Autoradiographs of tissues fixed in glutaraldehyde alone confirm that adrenaline is lost from sections by this technique. When 1-5% potassium dichromate is added to glutaraldehyde then adrenline is fixed in A cells and these show only a slightly decreased grain count as compared to NA cells at 5 days; this slight decrease is probably due to more rapid turnover of amines by A cells.,On the fixation of catecholamines including adrenaline in tissue sections Abs: Following intravenous or intraperitoneal injections of 3H-l-dopa radioactivity in adrenal medullary chromaffin cells of the mouse has been followed by autoradiographic and radioisotopic assay methods. For autoradiographic purposes tissues were fixed in either phosphate buffered glutaraldehyde or in 1-5% potassium dichromate in glutaraldehyde pH 7-2. A high initial radioactivity is demonstrated by both autoradiography and radioisotopic assay. During the first hour dopamine is the predominant labelled amine. Between 1 and 4 hours after the injection noradrenaline is in highest concentration and from 1 to 24 hours labelled adrenaline appears and becomes the predominant labelled amine (about 70%) after 24 hours. Autoradiographs of tissues fixed in glutaraldehyde alone confirm that adrenaline is lost from sections by this technique. When 1-5% potassium dichromate is added to glutaraldehyde then adrenline is fixed in A cells and these show only a slightly decreased grain count as compared to NA cells at 5 days; this slight decrease is probably due to more rapid turnover of amines by A cells.
1235145,Ryley et al. 1976,Methods in coccidiosis research: separation of oocysts from faeces,"Factors which may be important in the large-scale extraction of coccidial oocysts from faeces ha.ve been investigated with Eimeria tenella. Age of bird, inoculum, feeding status at the time of inoculation, period of collection, feeding status during collection, collection medium, homogenization and sieving, flotation, washing, sporulation and further purification have all been considered. The aim has been to establish a method to produce the maximum number of oocysts of a required degree of purity and viability, with the expenditure of the minimum amount of physical effort, time, animals and chemicals. In our method, groups of chickens 3-4 weeks of age are inoculated with 5000 oocysts of E. tenella and food is supplied ad lib. Over the period 5-8 days after inoculation, faeces are collected in trays containing 2% (w/v) potassium dichromate solution, while food intake is restricted. The faecal material is homogenized, passed once through 40 and 100 mesh sieves, centrifuged and the oocysts recovered from the sediment by 3 flotations in saturated salt solution. Following washing, oocysts are sporulated by forced aeration at 30 degrees C and may be further purified by hypochlorite treatment, or passage in 5% Tween 80 solution through a glass bead column followed by sucrose density gradient centrifugation. Routine passages along these lines over a 5 year period have given a recovery of 46% of the oocysts excreted by over 7000 birds.","Methods in coccidiosis research: separation of oocysts from faeces Abs: Factors which may be important in the large-scale extraction of coccidial oocysts from faeces ha.ve been investigated with Eimeria tenella. Age of bird, inoculum, feeding status at the time of inoculation, period of collection, feeding status during collection, collection medium, homogenization and sieving, flotation, washing, sporulation and further purification have all been considered. The aim has been to establish a method to produce the maximum number of oocysts of a required degree of purity and viability, with the expenditure of the minimum amount of physical effort, time, animals and chemicals. In our method, groups of chickens 3-4 weeks of age are inoculated with 5000 oocysts of E. tenella and food is supplied ad lib. Over the period 5-8 days after inoculation, faeces are collected in trays containing 2% (w/v) potassium dichromate solution, while food intake is restricted. The faecal material is homogenized, passed once through 40 and 100 mesh sieves, centrifuged and the oocysts recovered from the sediment by 3 flotations in saturated salt solution. Following washing, oocysts are sporulated by forced aeration at 30 degrees C and may be further purified by hypochlorite treatment, or passage in 5% Tween 80 solution through a glass bead column followed by sucrose density gradient centrifugation. Routine passages along these lines over a 5 year period have given a recovery of 46% of the oocysts excreted by over 7000 birds."
1235144,Veien and  Kaaber 1976,Latent metal hypersensitivity among patients with pompholyx,,Latent metal hypersensitivity among patients with pompholyx Abs: 
1235143,Rudzki et al. 1976,Patch tests with potassium dichromate removed after 24 and 48 hours,"The rate of release in vitro of four potassium dichromate concentrations (0.5, 0.1, 0.05 and 0.01%) was determined. In the course of 24 h, 90.1-97.5% was released of the total K2Cr2O7 amount in 48 h. Out of 30 patients positive to 0.05% dichromate when the patch test was done routinely, 29 were also positive when the patch was removed after 24 h. The effect of the earlier removal of the patch test was also noted in seven other patients, when results of tests with lower dichromate concentrations were taken into account.","Patch tests with potassium dichromate removed after 24 and 48 hours Abs: The rate of release in vitro of four potassium dichromate concentrations (0.5, 0.1, 0.05 and 0.01%) was determined. In the course of 24 h, 90.1-97.5% was released of the total K2Cr2O7 amount in 48 h. Out of 30 patients positive to 0.05% dichromate when the patch test was done routinely, 29 were also positive when the patch was removed after 24 h. The effect of the earlier removal of the patch test was also noted in seven other patients, when results of tests with lower dichromate concentrations were taken into account."
1235141,Fisher 1977,Fifty years experience with contact dermatitis,,Fifty years experience with contact dermatitis Abs: 
1235137,Levis et al. 1977,Inhibition of DNA synthesis in BHK fibroblasts treated in vitro with potassium dichromate,"Treatment of hamster fibroblasts with potassium dichromate in vitro stimulates tritiated thymidine uptake into the intracellular nucleotide pool. This effect is due to the oxidizing action of hexavalent chromium on the plasma membrane. Dichromate, induces also an inhibition of DNA replication, which is due to the interaction of reduced trivalent chromium with specific biological ligands on the DNA molecule.","Inhibition of DNA synthesis in BHK fibroblasts treated in vitro with potassium dichromate Abs: Treatment of hamster fibroblasts with potassium dichromate in vitro stimulates tritiated thymidine uptake into the intracellular nucleotide pool. This effect is due to the oxidizing action of hexavalent chromium on the plasma membrane. Dichromate, induces also an inhibition of DNA replication, which is due to the interaction of reduced trivalent chromium with specific biological ligands on the DNA molecule."
1235135,Kratochvil and  Jeremy 1977,Determination of calcium in urine by manual microtitration with EDTA,"A simple, direct method for the determination of total calcium in urine by manual microtitration with EDTA at pH 12, with Calocin as fluorescent indicator, is proposed. By use of urine sample volumes of only 0.01-0.05 ml, interference from phosphate and natural fluorescence is minimized. For strongly naturally fluorescing urines the addition of potassium dichromate provides effective quenching. Agreement between results obtained by the proposed method and by atomic-absorption spectroscopy for a series of urine samples was satisfactory.","Determination of calcium in urine by manual microtitration with EDTA Abs: A simple, direct method for the determination of total calcium in urine by manual microtitration with EDTA at pH 12, with Calocin as fluorescent indicator, is proposed. By use of urine sample volumes of only 0.01-0.05 ml, interference from phosphate and natural fluorescence is minimized. For strongly naturally fluorescing urines the addition of potassium dichromate provides effective quenching. Agreement between results obtained by the proposed method and by atomic-absorption spectroscopy for a series of urine samples was satisfactory."
1235134,Stroo and  Hook 1977,Enzymes of renal origin in urine as indicators of nephrotoxicity,"HEEP COPYRIGHT: BIOL ABS. One of the 1st ultrastructural changes seen after treatment with many nephrotoxins is sloughing of proximal tubule brush borders. Maltase and alkaline phosphatase in the kidney are localized in the brush border of the proximal tubule. Thus, increased activity of these enzymes in the urine should follow sloughing of brush border into the urine. The object of this investigation was to test the hypothesis that, following treatment with known nephrotoxins, increased urinary maltase and alkaline phosphatase activities could be measured prior to the development of other signs of nephrotoxicity. Male Sprague-Dawley rats were treated with HgCl2 (1 mg/kg), K2Cr2O7 (15 mg/kg), or saline, i.p. Total enzyme activity was determined in fresh (maltase) or dialyzed (alkaline phosphatase) urine. Maltase and alkaline phosphatase activities were both elevated in the 0- to 4-hr urine samples after K2Cr2O7. After HgCl2, increased enzymuria first occurred at 9-24 h. In both cases, these effects appeared to be reversible, returning to control values by 48 h. Urine enzymes and blood urea N (BUN) were compared 24 h after several doses of HgCl2. Urinary enzyme activity was significantly increased after 1 mg/kg, before BUN was increased (2 mg/kg). After K2Cr2O7, uranyl acetate, neomycin, folic acid and carbon tetrachloride, BUN was increased without affecting urinary enzyme activity or at the same dose that increased enzyme excretion. Thus, it appears that increased activities of maltase and alkaline phosphatase in the urine could be used as noninvasive, nondestructive indexes of renal damage, but may be no more sensitive than methods currently available.","Enzymes of renal origin in urine as indicators of nephrotoxicity Abs: HEEP COPYRIGHT: BIOL ABS. One of the 1st ultrastructural changes seen after treatment with many nephrotoxins is sloughing of proximal tubule brush borders. Maltase and alkaline phosphatase in the kidney are localized in the brush border of the proximal tubule. Thus, increased activity of these enzymes in the urine should follow sloughing of brush border into the urine. The object of this investigation was to test the hypothesis that, following treatment with known nephrotoxins, increased urinary maltase and alkaline phosphatase activities could be measured prior to the development of other signs of nephrotoxicity. Male Sprague-Dawley rats were treated with HgCl2 (1 mg/kg), K2Cr2O7 (15 mg/kg), or saline, i.p. Total enzyme activity was determined in fresh (maltase) or dialyzed (alkaline phosphatase) urine. Maltase and alkaline phosphatase activities were both elevated in the 0- to 4-hr urine samples after K2Cr2O7. After HgCl2, increased enzymuria first occurred at 9-24 h. In both cases, these effects appeared to be reversible, returning to control values by 48 h. Urine enzymes and blood urea N (BUN) were compared 24 h after several doses of HgCl2. Urinary enzyme activity was significantly increased after 1 mg/kg, before BUN was increased (2 mg/kg). After K2Cr2O7, uranyl acetate, neomycin, folic acid and carbon tetrachloride, BUN was increased without affecting urinary enzyme activity or at the same dose that increased enzyme excretion. Thus, it appears that increased activities of maltase and alkaline phosphatase in the urine could be used as noninvasive, nondestructive indexes of renal damage, but may be no more sensitive than methods currently available."
1235132,Levis and  Buttignol 1977,Effects of potassium dichromate on DNA synthesis in hamster fibroblasts,"HEEP COPYRIGHT: BIOL ABS. The carcinogen K2Cr2O7 independently interferes with thymidine (TdR) uptake and DNA synthesis in hamster fibroblasts cultured in vitro. The increased uptake of (3H)TdR in the intracellular pool may depend on the activation by Cr of specific receptors involved in the facilitated transport and phosphorylation of nucleosides across the plasma membrane (e.g., permeases and kinases). Or it may be due to the inhibition of endogenous nucleoside synthesis, giving rise to decreased unlabeled thymidine concentrations inside the cell. These, at labeling could influence the uptake of 3H precursors by a simple diffusion mechanism which leads to reequilibration of nucleotide levels. After the amounts of hexavalent and trivalent Cr are determined, in the solutions used for treatment and inside the cells, and after the biological actions of K2Cr2O7 and of CrCl3, a trivalent Cr salt, are compared, it becomes clear that the stimulation of (3H)TdR uptake is due to the reduction of hexavalent Cr on the plasma membrane. Such reduction appears to be necessary for the penetration of active Cr complexes into the cell. The present data indicate that DNA replication is inhibited by 10-4 M K2Cr2O7 and its recovery depends on the conditions and duration of treatment as well as the concentrations of dichromate. DNA synthesis inhibition represents the primary effect of reduced trivalent Cr inside the cell, while RNA and protein syntheses are only secondarily inhibited","Effects of potassium dichromate on DNA synthesis in hamster fibroblasts Abs: HEEP COPYRIGHT: BIOL ABS. The carcinogen K2Cr2O7 independently interferes with thymidine (TdR) uptake and DNA synthesis in hamster fibroblasts cultured in vitro. The increased uptake of (3H)TdR in the intracellular pool may depend on the activation by Cr of specific receptors involved in the facilitated transport and phosphorylation of nucleosides across the plasma membrane (e.g., permeases and kinases). Or it may be due to the inhibition of endogenous nucleoside synthesis, giving rise to decreased unlabeled thymidine concentrations inside the cell. These, at labeling could influence the uptake of 3H precursors by a simple diffusion mechanism which leads to reequilibration of nucleotide levels. After the amounts of hexavalent and trivalent Cr are determined, in the solutions used for treatment and inside the cells, and after the biological actions of K2Cr2O7 and of CrCl3, a trivalent Cr salt, are compared, it becomes clear that the stimulation of (3H)TdR uptake is due to the reduction of hexavalent Cr on the plasma membrane. Such reduction appears to be necessary for the penetration of active Cr complexes into the cell. The present data indicate that DNA replication is inhibited by 10-4 M K2Cr2O7 and its recovery depends on the conditions and duration of treatment as well as the concentrations of dichromate. DNA synthesis inhibition represents the primary effect of reduced trivalent Cr inside the cell, while RNA and protein syntheses are only secondarily inhibited"
1235130,Blythman and  Forman 1977,The use of preserved milk samples in the Brucella milk ring test,"Brucella milk ring tests (BMRT's) were performed on fresh herd milk samples and pooled samples, preserved at a processing factory with potassium dichromate. Preserved milk from samples pooled over a 10-day period, gave results that were similar to an average result for individual fresh daily samples over the same period. When fresh samples gave variable results and the pooled preserved sample gave a negative result, it was considered that the latter result was more reliable, possibly due to factors causing false positive reactions being diluted. Blood testing of herds for circulating antibody indicated that the use of either fresh or preserved milk samples could occasionally produce false negative or false positive results.","The use of preserved milk samples in the Brucella milk ring test Abs: Brucella milk ring tests (BMRT's) were performed on fresh herd milk samples and pooled samples, preserved at a processing factory with potassium dichromate. Preserved milk from samples pooled over a 10-day period, gave results that were similar to an average result for individual fresh daily samples over the same period. When fresh samples gave variable results and the pooled preserved sample gave a negative result, it was considered that the latter result was more reliable, possibly due to factors causing false positive reactions being diluted. Blood testing of herds for circulating antibody indicated that the use of either fresh or preserved milk samples could occasionally produce false negative or false positive results."
1235129,Rudski and  Czerwinska-Dihnz 1977,Sensitivity to dichromate in milk testers,,Sensitivity to dichromate in milk testers Abs: 
1235122,Puzanowska-Tarasiewicz et al. 1977,Use of diethazine hydrochloride for the extractive spectrophotometric determination of uranium and as a redox indicator,"Optimum conditions have been established for the formation and extraction of the complex formed from diethazine, thiocyanate and uranium(VI). An extractive spectrophotometric method for the determination of uranium(VI) is described. Experimental conditions have been also established for the direct titrimetric determination of uranium(IV) with potassium dichromate, using diethazine hydrochloride as redox indicator. Interferences have been considered.","Use of diethazine hydrochloride for the extractive spectrophotometric determination of uranium and as a redox indicator Abs: Optimum conditions have been established for the formation and extraction of the complex formed from diethazine, thiocyanate and uranium(VI). An extractive spectrophotometric method for the determination of uranium(VI) is described. Experimental conditions have been also established for the direct titrimetric determination of uranium(IV) with potassium dichromate, using diethazine hydrochloride as redox indicator. Interferences have been considered."
1235120,Feinfeld et al. 1977,Ligandinuria in nephrotoxic acute tubular necrosis,"Ligandin (GSH-S-transferase B), an abundant intracellular soluble protein in rat proximal tubules, hepatocytes, and small intestinal mucosal cells, is believed to be a component of an organic anion transport system. Its presence in urine was determined immunologically and catalytically in adult, female, Sprague-Dawley rats that were given mercuric chloride or potassium dichromate. These nephrotoxic agents produce severe renal failure, with epithelial necrosis in the proximal tubule. Mercuric chloride perferentially injures the terminal part of the proximal tubule, while potassium dichromate damages more proximal segments. Ligandinuria was consistently detected immunologically and catalytically from 6 to 24 hr following injection of mercuric chloride. Potassium dichromate administration did not result in immunologically detectable liganduria; however, GSH-S-transferase activity, which provides a more sensitive assay, was frequently detected. The findings are consistent with immunofluorescent localization of ligandin in the proximal tubule. Immunologic or enzymatic measurement of ligandin in urine may provide a sensitive index of acute injury to the proximal tubule.","Ligandinuria in nephrotoxic acute tubular necrosis Abs: Ligandin (GSH-S-transferase B), an abundant intracellular soluble protein in rat proximal tubules, hepatocytes, and small intestinal mucosal cells, is believed to be a component of an organic anion transport system. Its presence in urine was determined immunologically and catalytically in adult, female, Sprague-Dawley rats that were given mercuric chloride or potassium dichromate. These nephrotoxic agents produce severe renal failure, with epithelial necrosis in the proximal tubule. Mercuric chloride perferentially injures the terminal part of the proximal tubule, while potassium dichromate damages more proximal segments. Ligandinuria was consistently detected immunologically and catalytically from 6 to 24 hr following injection of mercuric chloride. Potassium dichromate administration did not result in immunologically detectable liganduria; however, GSH-S-transferase activity, which provides a more sensitive assay, was frequently detected. The findings are consistent with immunofluorescent localization of ligandin in the proximal tubule. Immunologic or enzymatic measurement of ligandin in urine may provide a sensitive index of acute injury to the proximal tubule."
1235114,Wagner and  Rexinger 1978,In vivo effects of mebendazole and levamisole in the treatment of trichuriasis and ascariasis,"The anthelmintic drugs mebendazole (Vermox) and levamisole were tested in patients for their possible ovicidal effects on the eggs of Trichuris trichiura and Ascaris lumbricoides. The patients studied were 20 Africans of Sierra Leone, and 11 children of Nassau, Bahamas. Egg counts were made before treatment, and for 5 consecutive days following treatment. Eggs were incubated in 2.5% aqueous potassium dichromate and percentages of larval development were determined. Mebendazole completely inhibited the development of the eggs of T. trichiura by day 3 of the follow-up period. The ovicidal action of mebendazole on the eggs of A. lumbricoides was determined to be 64.8% by day 5 of the follow-up study. Levamisole had little (11.6%) ovicidal action on the eggs of T. trichiura and no ovicidal activity for A. lumbricoides.","In vivo effects of mebendazole and levamisole in the treatment of trichuriasis and ascariasis Abs: The anthelmintic drugs mebendazole (Vermox) and levamisole were tested in patients for their possible ovicidal effects on the eggs of Trichuris trichiura and Ascaris lumbricoides. The patients studied were 20 Africans of Sierra Leone, and 11 children of Nassau, Bahamas. Egg counts were made before treatment, and for 5 consecutive days following treatment. Eggs were incubated in 2.5% aqueous potassium dichromate and percentages of larval development were determined. Mebendazole completely inhibited the development of the eggs of T. trichiura by day 3 of the follow-up period. The ovicidal action of mebendazole on the eggs of A. lumbricoides was determined to be 64.8% by day 5 of the follow-up study. Levamisole had little (11.6%) ovicidal action on the eggs of T. trichiura and no ovicidal activity for A. lumbricoides."
1235110,Feuerman 1978,Housewives' skin and the hazards of detergents,,Housewives' skin and the hazards of detergents Abs: 
1235109,Rudzki et al. 1978,Contact sensitivity to trivalent chromium compounds,"The investigations confirmed the known fact that for skin tests larger amounts of trivalent chromium compounds are necessary than those of potassium dichromate. It was also observed that some patients react to relatively higher Cr VI and lower Cr III concentrations and others vice versa. Chromium nitrate and chloride release and that of potassium dichromate was determined and converted to the chromium content in the concentrations used for skin tests. It was found that Cr III compounds cannot be used for skin tests in a 0,5% concentration if only because they are released in undeterminable amounts. Release of Cr III and potassium dichromate from bases containing the same amount of substance when converted to chromium demonstrated that the different release of Cr III is not an additional cause of the fact that much higher concentrations of Cr III compounds have to be used for patch tests than those of Cr VI compounds.","Contact sensitivity to trivalent chromium compounds Abs: The investigations confirmed the known fact that for skin tests larger amounts of trivalent chromium compounds are necessary than those of potassium dichromate. It was also observed that some patients react to relatively higher Cr VI and lower Cr III concentrations and others vice versa. Chromium nitrate and chloride release and that of potassium dichromate was determined and converted to the chromium content in the concentrations used for skin tests. It was found that Cr III compounds cannot be used for skin tests in a 0,5% concentration if only because they are released in undeterminable amounts. Release of Cr III and potassium dichromate from bases containing the same amount of substance when converted to chromium demonstrated that the different release of Cr III is not an additional cause of the fact that much higher concentrations of Cr III compounds have to be used for patch tests than those of Cr VI compounds."
1235108,Murty and  Rao 1978,Determination of iodide with potassium dichromate and sodium vanadate in the presence of acetone,"The determination of iodide with potassium dichromate and sodium vanadate in 6-8M phosphoric acid medium by potentiometric or visual titration is described. Ferroin and barium diphenylamine sulphonate (BDAS) are used as the indicators in the visual titration with potassium dichromate and sodium vanadate respectively. Acetone is used to stabilize the iodonium ions liberated, in the visual titration. Iodide can also be determined with sodium vanadate in 2-4M sulphuric acid medium with BDAS as indicator in the presence of oxalic acid as catalyst and acetone to stabilize the liberated iodine cations. The visual procedures are applied for the determination of iodide in tincture of iodine. The formal potentials of the iodine/iodide couple in various phosphoric acid media are reported.","Determination of iodide with potassium dichromate and sodium vanadate in the presence of acetone Abs: The determination of iodide with potassium dichromate and sodium vanadate in 6-8M phosphoric acid medium by potentiometric or visual titration is described. Ferroin and barium diphenylamine sulphonate (BDAS) are used as the indicators in the visual titration with potassium dichromate and sodium vanadate respectively. Acetone is used to stabilize the iodonium ions liberated, in the visual titration. Iodide can also be determined with sodium vanadate in 2-4M sulphuric acid medium with BDAS as indicator in the presence of oxalic acid as catalyst and acetone to stabilize the liberated iodine cations. The visual procedures are applied for the determination of iodide in tincture of iodine. The formal potentials of the iodine/iodide couple in various phosphoric acid media are reported."
1235106,Kunstýr and  Ammerpohl 1978,Resistance of faecal cysts of Spironucleus muris to some physical factors and chemical substances,"The effect of 5 disinfectants, and of saturated zinc chloride solution + sodium chloride solution, 2.5% potassium dichromate solution, and 0.12% dimetridazole on faecal cysts of Spironucleus muris were tested in vitro. The resistance of the cysts to high and low temperatures, low pH, high osmotic pressure, centrifugation and desiccation was also tested. After treatment the morphology of the cysts was observed microscopically and their infectivity tested in vivo on sensitive thymus-deficient nude mice. The cysts ceased to be infective after treatment with most of usual disinfectants and by high temperature (45 degrees C for 30 min). They resisted 0.12% dimetridazole, low temperature (-196 degrees C), low pH (2.2), high osmotic pressure (distilled water and 30% 'Ficoll'), centrifugation (1500 g/20 min) and desiccation (room temperature for 14 days). These data may be useful for the control of Spironucleus muris infection in rodents and for cryopreservation of the parasite for experimental purposes.","Resistance of faecal cysts of Spironucleus muris to some physical factors and chemical substances Abs: The effect of 5 disinfectants, and of saturated zinc chloride solution + sodium chloride solution, 2.5% potassium dichromate solution, and 0.12% dimetridazole on faecal cysts of Spironucleus muris were tested in vitro. The resistance of the cysts to high and low temperatures, low pH, high osmotic pressure, centrifugation and desiccation was also tested. After treatment the morphology of the cysts was observed microscopically and their infectivity tested in vivo on sensitive thymus-deficient nude mice. The cysts ceased to be infective after treatment with most of usual disinfectants and by high temperature (45 degrees C for 30 min). They resisted 0.12% dimetridazole, low temperature (-196 degrees C), low pH (2.2), high osmotic pressure (distilled water and 30% 'Ficoll'), centrifugation (1500 g/20 min) and desiccation (room temperature for 14 days). These data may be useful for the control of Spironucleus muris infection in rodents and for cryopreservation of the parasite for experimental purposes."
1235105,Sharma et al. 1978,Intravascular haemolysis and acute renal failure following potassium dichromate poisoning,An 18-year-old girl developed acute renal failure 24 hr after ingestion of potassium dichromate. Laboratory data revealed associated intravascular haemolysis. Renal histology showed features suggestive of acute tubular necrosis. She went into diuretic phase after 11 days of oliguria and subsequently regained normal renal function. Both direct toxic damage by dichromate and intravascular haemolysis may have contributed to the development of acute tubular necrosis and acute renal failure.,Intravascular haemolysis and acute renal failure following potassium dichromate poisoning Abs: An 18-year-old girl developed acute renal failure 24 hr after ingestion of potassium dichromate. Laboratory data revealed associated intravascular haemolysis. Renal histology showed features suggestive of acute tubular necrosis. She went into diuretic phase after 11 days of oliguria and subsequently regained normal renal function. Both direct toxic damage by dichromate and intravascular haemolysis may have contributed to the development of acute tubular necrosis and acute renal failure.
1235100,Moriearty et al. 1978,"Contact dermatitis in Salvador, Brazil","In Salvador, Brazil, 536 patients were patch tested with 24 contact allergens. The most common sensitizers included potassium dichromate, thimerosal, hydroquinone, nitrofurazone ointment and nickel sulfate. The results of this South American study are compared with those published by North American and European dermatologists. Low frequencies of positive reactions were encountered in Salvador to some substances, including mercury bichloride and p-phenylenediamine. The influences of climate and life style in determining patterns of contact sensitivity are discussed.","Contact dermatitis in Salvador, Brazil Abs: In Salvador, Brazil, 536 patients were patch tested with 24 contact allergens. The most common sensitizers included potassium dichromate, thimerosal, hydroquinone, nitrofurazone ointment and nickel sulfate. The results of this South American study are compared with those published by North American and European dermatologists. Low frequencies of positive reactions were encountered in Salvador to some substances, including mercury bichloride and p-phenylenediamine. The influences of climate and life style in determining patterns of contact sensitivity are discussed."
1235098,Foote et al. 1978,Cerebral arterial lesions resulting from inflammatory emboli,"In order to study the effects of septic embolism on the brain, silicone rubber emboli of various types were injected into the carotid arteries of 35 dogs. Pathologic and angiographic studies were performed to assess the resultant arterial and parenchymal lesions. Pure silicone rubber emboli (14 dogs) produced occasional intra-arterial thrombosis but no arteritis. Sterile and bacterially contaminated emboli containing a lead-chromate pigment (similar to those used in previous studies of septic embolism) (11 dogs) and pure silicone rubber emboli with transversely oriented canals (10 dogs), after brief placement in a bacterial suspension, were associated with intense inflammatory arteritis. This was accompanied by focal meningitis, subarachnoid hemorrhage, thrombosis, and cerebritis of the underlying cortex. The findings resembled those found in mycotic aneurysm. Aneurysmal dilatation was observed in one postmortem angiogram. In previous models of mycotic aneurysm, the inflammation attributed to bacterial contamination was probably due to the lead-chromate pigment used.","Cerebral arterial lesions resulting from inflammatory emboli Abs: In order to study the effects of septic embolism on the brain, silicone rubber emboli of various types were injected into the carotid arteries of 35 dogs. Pathologic and angiographic studies were performed to assess the resultant arterial and parenchymal lesions. Pure silicone rubber emboli (14 dogs) produced occasional intra-arterial thrombosis but no arteritis. Sterile and bacterially contaminated emboli containing a lead-chromate pigment (similar to those used in previous studies of septic embolism) (11 dogs) and pure silicone rubber emboli with transversely oriented canals (10 dogs), after brief placement in a bacterial suspension, were associated with intense inflammatory arteritis. This was accompanied by focal meningitis, subarachnoid hemorrhage, thrombosis, and cerebritis of the underlying cortex. The findings resembled those found in mycotic aneurysm. Aneurysmal dilatation was observed in one postmortem angiogram. In previous models of mycotic aneurysm, the inflammation attributed to bacterial contamination was probably due to the lead-chromate pigment used."
1235095,Kobayashi et al. 1978,SGC (small granule chromaffin) cells in the mouse adrenal medulla: light and electron microscopic identification using semi-thin and ultra-thin sections,"Adrenal glands of the mouse, fixed either in glutaraldehyde followed by osmium tetroxide or in a mixture of potassium dichromate and glutaraldehyde, and embedded in Epon 812, were investigated by light and electron microscopy. An argentaffin reaction was applied to semi-thin sections for light microscopy and to ultra-thin sections for electron microscopy. Since the mature secretory granules in the Small Granule Chromaffin (SGC) cell were argentaffin and were mainly located along the cell membrane, this cell was clearly distinguishable under the light microscope both from the A (adrenaline) cell whose secretory granules were non-argentaffin and from the NA (noradrenaline) cell whose cytoplasm was rich and was filled with large, strongly argentaffin granules. Chromaffinity of the SGC cell was demonstrated under the light microscope. The SGC cell was intensively stained with toluidine blue without revealing metachromasia. It was demonstrated at the EM level that not only the secretory granules but also the synaptic-like vesicles in the SGC cell contained argentaffin substances. Possible functional relationship between the secretory granules and the synaptic-like vesicles was discussed.","SGC (small granule chromaffin) cells in the mouse adrenal medulla: light and electron microscopic identification using semi-thin and ultra-thin sections Abs: Adrenal glands of the mouse, fixed either in glutaraldehyde followed by osmium tetroxide or in a mixture of potassium dichromate and glutaraldehyde, and embedded in Epon 812, were investigated by light and electron microscopy. An argentaffin reaction was applied to semi-thin sections for light microscopy and to ultra-thin sections for electron microscopy. Since the mature secretory granules in the Small Granule Chromaffin (SGC) cell were argentaffin and were mainly located along the cell membrane, this cell was clearly distinguishable under the light microscope both from the A (adrenaline) cell whose secretory granules were non-argentaffin and from the NA (noradrenaline) cell whose cytoplasm was rich and was filled with large, strongly argentaffin granules. Chromaffinity of the SGC cell was demonstrated under the light microscope. The SGC cell was intensively stained with toluidine blue without revealing metachromasia. It was demonstrated at the EM level that not only the secretory granules but also the synaptic-like vesicles in the SGC cell contained argentaffin substances. Possible functional relationship between the secretory granules and the synaptic-like vesicles was discussed."
1235092,Foote et al. 1978,Effects of anticoagulants in an animal model of septic cerebral embolization,"The effect of anticoagulation on lesions caused by cerebral emboli of different types was studied in 57 dogs. The resultant arterial and parenchymal lesions were assessed by pathologic and angiographic studies. Embolization with emboli that caused little or no inflammatory response in the artery (12 dogs) was not associated with hemorrhagic infarcts or with subdural or subarachnoid hemorrhage; furthermore, treatment with anticoagulants (9 dogs) did not change the character of the lesions. Embolization with emboli that caused arteritis, that is, bacterial contamination or presence of lead chromate in the embolus (21 dogs), was associated with hemorrhagic infarcts, focal subarachnoid hemorrhage, and increased incidence of acute subdural hemorrhage. Treatment with anticoagulants (16 dogs) was associated with a further increase in the incidence of subdural hemorrhage.","Effects of anticoagulants in an animal model of septic cerebral embolization Abs: The effect of anticoagulation on lesions caused by cerebral emboli of different types was studied in 57 dogs. The resultant arterial and parenchymal lesions were assessed by pathologic and angiographic studies. Embolization with emboli that caused little or no inflammatory response in the artery (12 dogs) was not associated with hemorrhagic infarcts or with subdural or subarachnoid hemorrhage; furthermore, treatment with anticoagulants (9 dogs) did not change the character of the lesions. Embolization with emboli that caused arteritis, that is, bacterial contamination or presence of lead chromate in the embolus (21 dogs), was associated with hemorrhagic infarcts, focal subarachnoid hemorrhage, and increased incidence of acute subdural hemorrhage. Treatment with anticoagulants (16 dogs) was associated with a further increase in the incidence of subdural hemorrhage."
1235086,Bräunlich et al. 1979,Stimulation of kidney function in rats of different ages injured by nephrotoxic agents,"Intensity and duration of nephrotoxic effects can be characterized by measurement of renal p-aminohippurate (PAH) excretion. Single administration of potassium dichromate or glycerol is followed by a marked decrease of renal PAH excretion in dependence on the time after the administration as well as on the dosage used. Both agents are without effect in young rats with an immature tubular transport system for organic anions. As observed previously in rats with intact kidney function, renal PAH excretion can also be stimulated in rats with potassium dichromate or glycerol induced kidney damage. Stimulation of renal PAH excretion is possible in injured rats by repeated administrations of PAH and cyclopenthiazide, respectively. Exactly, the duration of injury is shortened whereas the intensity of the nephrotoxic effect is not changed. However, this effect depends on the age of rats as well as on the nephrotoxic agent administered.","Stimulation of kidney function in rats of different ages injured by nephrotoxic agents Abs: Intensity and duration of nephrotoxic effects can be characterized by measurement of renal p-aminohippurate (PAH) excretion. Single administration of potassium dichromate or glycerol is followed by a marked decrease of renal PAH excretion in dependence on the time after the administration as well as on the dosage used. Both agents are without effect in young rats with an immature tubular transport system for organic anions. As observed previously in rats with intact kidney function, renal PAH excretion can also be stimulated in rats with potassium dichromate or glycerol induced kidney damage. Stimulation of renal PAH excretion is possible in injured rats by repeated administrations of PAH and cyclopenthiazide, respectively. Exactly, the duration of injury is shortened whereas the intensity of the nephrotoxic effect is not changed. However, this effect depends on the age of rats as well as on the nephrotoxic agent administered."
1235085,Enhorning et al. 1979,Isoxsuprine infusion to the pregnant rabbit and its effect on fetal lung surfactant,"Rabbit does, pregnant on the 28th day, were infused with isoxsuprine 2.5 mg/kg body weight/h in 50 ml 5% glucose, or with glucose only. The isoxsuprine caused maternal heart rate to increase and blood pressure, mean and diastolic, to decrease. The volume of fetal pulmonary fluid (FPF) and the wet lung weight/body weight ratio were significantly lowered by isoxsuprine. Lecithin/sphingomyelin ratio of FPF in isoxsuprine-infused animals was higher, compared with controls, not infused. Minimal surface tension of FPF, evaluated with pulsating bubble, was significantly lower in treated fetuses. Histologic examination of the fetal lungs after fixation with potassium dichromate and mercuric chloride showed that in isoxsuprine-treated litters FPF contained more granular and sudanophilic material. The results offer further evidence that isoxsuprine causes dehydration of fetal lungs and a release of pulmonary surfactant.","Isoxsuprine infusion to the pregnant rabbit and its effect on fetal lung surfactant Abs: Rabbit does, pregnant on the 28th day, were infused with isoxsuprine 2.5 mg/kg body weight/h in 50 ml 5% glucose, or with glucose only. The isoxsuprine caused maternal heart rate to increase and blood pressure, mean and diastolic, to decrease. The volume of fetal pulmonary fluid (FPF) and the wet lung weight/body weight ratio were significantly lowered by isoxsuprine. Lecithin/sphingomyelin ratio of FPF in isoxsuprine-infused animals was higher, compared with controls, not infused. Minimal surface tension of FPF, evaluated with pulsating bubble, was significantly lower in treated fetuses. Histologic examination of the fetal lungs after fixation with potassium dichromate and mercuric chloride showed that in isoxsuprine-treated litters FPF contained more granular and sudanophilic material. The results offer further evidence that isoxsuprine causes dehydration of fetal lungs and a release of pulmonary surfactant."
1235084,Lidén and  Lundberg 1979,Penetration of chromium in intact human skin in vivo,"Graphite furnace atomic absorption spectroscopy was modified to permit analysis of solid material, thereby fully utilizing the high sensitivity of the method. Tangential sections of biopsies from skin tested epicutaneously with K2Cr2O7 were analyzed for the content of chromium 5, 24, and 72 hr after application of the test substance in various concentrations, either in petrolatum or in water. The concentration of chromium as a rule showed 2 maxima, one at the dermal-epidermal junction and the other in upper mid-dermis. The content of chromium was of the same order of magnitude at all 3 times after application. This indicates that a steady state is reached already after 5 hr and that penetration is continuing at 72 hr. The chromium content in normal skin was 0.4-2 ppm. K2Cr2O7 in petrolatum penetrated to a greater extent than in water. The relative penetration of chromium was lower for 0.5% concentration than for 0.05%. A complex of chromium and glycine was found to penetrate into the skin but to a lower extent than K2Cr2O7. It also elicited a positive epicutaneous test reaction in 1 out of 2 individuals hypersensitive to chromium.","Penetration of chromium in intact human skin in vivo Abs: Graphite furnace atomic absorption spectroscopy was modified to permit analysis of solid material, thereby fully utilizing the high sensitivity of the method. Tangential sections of biopsies from skin tested epicutaneously with K2Cr2O7 were analyzed for the content of chromium 5, 24, and 72 hr after application of the test substance in various concentrations, either in petrolatum or in water. The concentration of chromium as a rule showed 2 maxima, one at the dermal-epidermal junction and the other in upper mid-dermis. The content of chromium was of the same order of magnitude at all 3 times after application. This indicates that a steady state is reached already after 5 hr and that penetration is continuing at 72 hr. The chromium content in normal skin was 0.4-2 ppm. K2Cr2O7 in petrolatum penetrated to a greater extent than in water. The relative penetration of chromium was lower for 0.5% concentration than for 0.05%. A complex of chromium and glycine was found to penetrate into the skin but to a lower extent than K2Cr2O7. It also elicited a positive epicutaneous test reaction in 1 out of 2 individuals hypersensitive to chromium."
1235083,Bianchi et al. 1979,Differential cytotoxic activity of potassium dichromate on nucleoside uptake in BHK fibroblasts,"In cultures of hamster fibroblasts (BHK cell line) treated with potassium dichromate (K2Cr2O7) nucleic acid and protein syntheses are differentially inhibited, and nucleoside uptake into the intracellular pool is characterized by a stimulation phase followed by an inhibition phase. Different patterns are observed for the uptake of each ribo- and deoxyribonucleoside, pyrimidine nucleoside (particularly deoxycytidine) uptake reaching the highest stimulation level. Kinetics of thymidine and deoxycytidine initial uptake at different exogenous nucleoside concentrations show that K2Cr2O7 affects both simple and facilitated diffusion of nucleosides. The time course of thymidine and deoxycytidine pool saturation suggests however that the effects of K2Cr2O7 on plasma membrane permeability are partially counterbalanced by modifications of pool size deriving from the concomitant alteration of steps of nucleoside metabolism separate from nucleoside uptake.","Differential cytotoxic activity of potassium dichromate on nucleoside uptake in BHK fibroblasts Abs: In cultures of hamster fibroblasts (BHK cell line) treated with potassium dichromate (K2Cr2O7) nucleic acid and protein syntheses are differentially inhibited, and nucleoside uptake into the intracellular pool is characterized by a stimulation phase followed by an inhibition phase. Different patterns are observed for the uptake of each ribo- and deoxyribonucleoside, pyrimidine nucleoside (particularly deoxycytidine) uptake reaching the highest stimulation level. Kinetics of thymidine and deoxycytidine initial uptake at different exogenous nucleoside concentrations show that K2Cr2O7 affects both simple and facilitated diffusion of nucleosides. The time course of thymidine and deoxycytidine pool saturation suggests however that the effects of K2Cr2O7 on plasma membrane permeability are partially counterbalanced by modifications of pool size deriving from the concomitant alteration of steps of nucleoside metabolism separate from nucleoside uptake."
1235082,Kaaber et al. 1979,Skin sensitivity to denture base materials in the burning mouth syndrome,"The significance of sensitizing compounds in the denture base for the etiology of the burning mouth syndrome (BMS) has been studied in 53 denture-wearing persons, seven males and 46 females. Epicutaneous patch tests were performed with standard concentrations of benzoyl peroxide, dibutylphthalate, dimethyl-p-toluidine, formaldehyde, hydroquinone, methylmethacrylate, p-phenylendiamine and with cadmium sulfate, potassium dichromate, cobalt chloride and nickel sulfate. Furthermore, patch testing was performed with filings from the denture mixed with the patient's own saliva. In cases with an inflamed oral mucosa, the presence of hyphae of Candida albicans was assessed by a smear technique. Positive skin reactions were observed in 15 persons to dimethyl-p-toluidine, hydroquinone, formaldehyde, methylmethacrylate, p-phenylendiamine, potassium dichromate, cobalt chloride and nickel sulfate, including three cases with reactions to filings from their dentures, and one patient who after subsequent testing showed skin sensitivity to balsam of Peru. In 12 cases an etiological connection could be traced between the oral symptoms and the denture base, indicating that contact sensitivity to base materials or to allergens and microbial antigens on the denture plate plays a greater role in the pathogenesis of BMS in edentulous persons than previously suggested.","Skin sensitivity to denture base materials in the burning mouth syndrome Abs: The significance of sensitizing compounds in the denture base for the etiology of the burning mouth syndrome (BMS) has been studied in 53 denture-wearing persons, seven males and 46 females. Epicutaneous patch tests were performed with standard concentrations of benzoyl peroxide, dibutylphthalate, dimethyl-p-toluidine, formaldehyde, hydroquinone, methylmethacrylate, p-phenylendiamine and with cadmium sulfate, potassium dichromate, cobalt chloride and nickel sulfate. Furthermore, patch testing was performed with filings from the denture mixed with the patient's own saliva. In cases with an inflamed oral mucosa, the presence of hyphae of Candida albicans was assessed by a smear technique. Positive skin reactions were observed in 15 persons to dimethyl-p-toluidine, hydroquinone, formaldehyde, methylmethacrylate, p-phenylendiamine, potassium dichromate, cobalt chloride and nickel sulfate, including three cases with reactions to filings from their dentures, and one patient who after subsequent testing showed skin sensitivity to balsam of Peru. In 12 cases an etiological connection could be traced between the oral symptoms and the denture base, indicating that contact sensitivity to base materials or to allergens and microbial antigens on the denture plate plays a greater role in the pathogenesis of BMS in edentulous persons than previously suggested."
1235081,van Ketel 1979,Petrolatum again: an adequate vehicle in cases of metal allergy?,,Petrolatum again: an adequate vehicle in cases of metal allergy? Abs: 
1235080,Mutti et al. 1979,Distribution and urinary excretion of chromium. Studies on rats after administration of single and repeated doses of potassium dichromate,,Distribution and urinary excretion of chromium. Studies on rats after administration of single and repeated doses of potassium dichromate Abs: 
1235078,Bass et al. 1979,Radioimmunoassay measurement of urinary ligandin excretion in nephrotoxin-treated rats,,Radioimmunoassay measurement of urinary ligandin excretion in nephrotoxin-treated rats Abs: 
1235077,Berndt 1979,Effects of toxic chemicals on renal transport processes,,Effects of toxic chemicals on renal transport processes Abs: 
1235076,Lachapelle and  Tennstedt 1979,Epidemiological survey of occupational contact dermatitis of the hands in Belgium,"A total of 400 patients suffering from hand eczema were patch tested to 25 chemicals (20 from the standard series of the ICDRG plus five from the Tri-Contact of Belgium); 197 (49.2%) had a positive patch test to one or more substances, and there was no significant difference in the prevalence between males and females. Potassium dichromate and PPD mix were statistically more frequently involved as skin allergens in males than in females, whereas nickel sulphate, thiuram mix and neomycin sulphate gave a significantly higher number of positive responses in women than in men. Results of this epidemiological survey are discussed in the light of similar studies from the literature.","Epidemiological survey of occupational contact dermatitis of the hands in Belgium Abs: A total of 400 patients suffering from hand eczema were patch tested to 25 chemicals (20 from the standard series of the ICDRG plus five from the Tri-Contact of Belgium); 197 (49.2%) had a positive patch test to one or more substances, and there was no significant difference in the prevalence between males and females. Potassium dichromate and PPD mix were statistically more frequently involved as skin allergens in males than in females, whereas nickel sulphate, thiuram mix and neomycin sulphate gave a significantly higher number of positive responses in women than in men. Results of this epidemiological survey are discussed in the light of similar studies from the literature."
1235075,Thormann et al. 1979,Persistence of contact allergy to chromium,Forty-eight patients with a positive patch test to potassium dichromate 0.5% were retested after 4-7 years; 38 patients (79%) still had a positive patch test. Chromate allergy seems to be persistent. In 72% of the cases a history of occupational exposure to chromates could be proved.,Persistence of contact allergy to chromium Abs: Forty-eight patients with a positive patch test to potassium dichromate 0.5% were retested after 4-7 years; 38 patients (79%) still had a positive patch test. Chromate allergy seems to be persistent. In 72% of the cases a history of occupational exposure to chromates could be proved.
1235074,Harahap et al. 1979,Contact allergens in north Sumatra (Indonesia),,Contact allergens in north Sumatra (Indonesia) Abs: 
1235073,Whiting et al. 1979,DNA damage and DNA repair in cultured human cells exposed to chromate,DNA damage and DNA repair have been observed in cultured human skin fibroblasts exposed to potassium chromate but not to a chromic glycine complex. DNA repair synthesis (unscheduled incorporation of [3H]thymidine (TdR)) was measured in cells during or following exposure to chromate and was significant for chromate concentrations above 10(-6) M. Maximal DNA repair was observed at about 10(-4) M chromate. DNA repair capacity was found to be saturated at this concentration. Chromate was stable for at least 8 h in culture medium and produced approximately a linear increase in repair with duration of exposure. DNA damage as determined by alkaline sucrose gradient sedimentation was detected after treatment for 1.5 h with 5 . 10(-4) M chromate. Exposure to 10(-7) M chromate solution for 7 days inhibited colony formation while acute (1 h) treatment was toxic at 5 . 10(-6) M. The chromic glycine complex was toxic above 10(-3) M for a 1-week exposure but was not observably toxic after a 1-h treatment. These results indicate that chromate and not chromic compounds may be the carcinogenic form for man. The nature of the ultimate carcinogen is discussed. These findings illustrate the utility of the DNA repair technique to study the effects on human cells of inorganic carcinogens and mutagens.,DNA damage and DNA repair in cultured human cells exposed to chromate Abs: DNA damage and DNA repair have been observed in cultured human skin fibroblasts exposed to potassium chromate but not to a chromic glycine complex. DNA repair synthesis (unscheduled incorporation of [3H]thymidine (TdR)) was measured in cells during or following exposure to chromate and was significant for chromate concentrations above 10(-6) M. Maximal DNA repair was observed at about 10(-4) M chromate. DNA repair capacity was found to be saturated at this concentration. Chromate was stable for at least 8 h in culture medium and produced approximately a linear increase in repair with duration of exposure. DNA damage as determined by alkaline sucrose gradient sedimentation was detected after treatment for 1.5 h with 5 . 10(-4) M chromate. Exposure to 10(-7) M chromate solution for 7 days inhibited colony formation while acute (1 h) treatment was toxic at 5 . 10(-6) M. The chromic glycine complex was toxic above 10(-3) M for a 1-week exposure but was not observably toxic after a 1-h treatment. These results indicate that chromate and not chromic compounds may be the carcinogenic form for man. The nature of the ultimate carcinogen is discussed. These findings illustrate the utility of the DNA repair technique to study the effects on human cells of inorganic carcinogens and mutagens.
1235071,Sullivan et al. 1979,The influence of oxidation state on the absorption of plutonium from the gastrointestinal tract,"HEEP COPYRIGHT: BIOL ABS. The effect of oxidation state on gastrointestinal Pu absorption was studied using solutions that contained, or did not contain, a strong oxidant and animals that were or were not fasted. There was no appreciable difference in the absorption of intragastrically injected 238Pu(IV) and 238Pu(VI) by either rats or guinea pigs allowed food ad lib and injected. To determine if the conditions used by Weeks et al. were responsible for the increased gut absorption of 239Pu(VI), relative to Pu(IV), both fasted and unfasted rats were gavaged with acid solutions of 239Pu(VI) nitrate, in the presence or absence of the holding oxidant (K2Cr2O7). The results indicated that the combination of dichromate and fasting increased absorption","The influence of oxidation state on the absorption of plutonium from the gastrointestinal tract Abs: HEEP COPYRIGHT: BIOL ABS. The effect of oxidation state on gastrointestinal Pu absorption was studied using solutions that contained, or did not contain, a strong oxidant and animals that were or were not fasted. There was no appreciable difference in the absorption of intragastrically injected 238Pu(IV) and 238Pu(VI) by either rats or guinea pigs allowed food ad lib and injected. To determine if the conditions used by Weeks et al. were responsible for the increased gut absorption of 239Pu(VI), relative to Pu(IV), both fasted and unfasted rats were gavaged with acid solutions of 239Pu(VI) nitrate, in the presence or absence of the holding oxidant (K2Cr2O7). The results indicated that the combination of dichromate and fasting increased absorption"
1235068,Veien and  Kaaber 1979,"Nickel, cobalt and chromium sensitivity in patients with pompholyx (dyshidrotic eczema)","Sixteen patients with negative routine patch tests were challenged orally in a controlled trial with 2.5 mg nickel, 1 mg cobalt, and 2.5 mg chromium given as salts of the respective metals. All of the patients had symmetrical, vesicular hand dermatitis and in some cases also foot involvement. The dermatitis of two patients flared after challenge with cobalt; in two patients flare occurred following chromate ingestion. Prior to the oral challenge all the patients were patch tested with nickel sulphate, cobalt chloride and potassium dichromate after adhesive tape stripping. Solutions of the same metal salts were used for intradermal testing. The intradermal test sites were read after 20 minutes and 48 hours, the patch tests after 48 h. Skin test reactivity correlated poorly to the results of the oral challenge, possibly due to nonspecific skin test reactivity. It is concluded that oral challenge is a valuable adjunctive diagnostic procedure in patients with pompholyx who have negative routine patch tests.","Nickel, cobalt and chromium sensitivity in patients with pompholyx (dyshidrotic eczema) Abs: Sixteen patients with negative routine patch tests were challenged orally in a controlled trial with 2.5 mg nickel, 1 mg cobalt, and 2.5 mg chromium given as salts of the respective metals. All of the patients had symmetrical, vesicular hand dermatitis and in some cases also foot involvement. The dermatitis of two patients flared after challenge with cobalt; in two patients flare occurred following chromate ingestion. Prior to the oral challenge all the patients were patch tested with nickel sulphate, cobalt chloride and potassium dichromate after adhesive tape stripping. Solutions of the same metal salts were used for intradermal testing. The intradermal test sites were read after 20 minutes and 48 hours, the patch tests after 48 h. Skin test reactivity correlated poorly to the results of the oral challenge, possibly due to nonspecific skin test reactivity. It is concluded that oral challenge is a valuable adjunctive diagnostic procedure in patients with pompholyx who have negative routine patch tests."
1235065,Stopp et al. 1980,Stimulation of kidney function in rats injured by nephrotoxic agents,"After single administration of potassium dichromate or glycerol, renal PAH excretion was markedly reduced in adult, but not in newborn and infant rats. As already demonstrated in rats with intact kidney functions, repeated administration of PAH or cyclopenthiazide stimulates also renal PAH excretion in rats with acute renal failure. In detail, after PAH or cyclopenthiazide treatment of rats the duration of injury is shortened whereas the intensity of the nephrotoxic effects is not changed. However, the stimulation depends on the age of animals as well as on the nephrotoxic agent administered.","Stimulation of kidney function in rats injured by nephrotoxic agents Abs: After single administration of potassium dichromate or glycerol, renal PAH excretion was markedly reduced in adult, but not in newborn and infant rats. As already demonstrated in rats with intact kidney functions, repeated administration of PAH or cyclopenthiazide stimulates also renal PAH excretion in rats with acute renal failure. In detail, after PAH or cyclopenthiazide treatment of rats the duration of injury is shortened whereas the intensity of the nephrotoxic effects is not changed. However, the stimulation depends on the age of animals as well as on the nephrotoxic agent administered."
1235064,Marlin et al. 1980,Effect of the dural application of Zenker's solution on the feline brain,"Zenker's solution is a tissue fixative containing mercuric chloride, potassium bichromate, sodium sulfate, and glacial acetic acid. In 1956, Anderson and Johnson reported its use in clinical neurosurgery. They applied the solution to the exposed dura after craniectomy. Delayed bone formation was thought to be due to the suppression of the osteoblastic activity of the outer layer of the dura. The fixative has since become a well-accepted adjuvant to the treatment of craniosynostosis. In 1972, Pawl and Sugar reported postoperative seizures in 6 of 34 patients treated with this solution. They assumed that the fixative penetrated the dura and irritated or damaged the cortex. To clarify the effect of Zenker's solution on the underlying brain, we performed bilateral parasagittal craniectomies in a group of kittens and adult cats. Zenker's solution was applied to one side and the other side served as a control. The animals were killed after periods varying from 24 hours to 2 months. We then examined the cortex under the craniectomies. There was immediate breakdown of the blood-brain barrier, as evidenced by the penetration of intravenous Evans blue. In the postoperative period investigated, an inflammatory response in the underlying brain with thickening of the arachnoid occurred. The results and implications of these experiments are presented. (Neurosurgery, 6: 45--48, 1980)","Effect of the dural application of Zenker's solution on the feline brain Abs: Zenker's solution is a tissue fixative containing mercuric chloride, potassium bichromate, sodium sulfate, and glacial acetic acid. In 1956, Anderson and Johnson reported its use in clinical neurosurgery. They applied the solution to the exposed dura after craniectomy. Delayed bone formation was thought to be due to the suppression of the osteoblastic activity of the outer layer of the dura. The fixative has since become a well-accepted adjuvant to the treatment of craniosynostosis. In 1972, Pawl and Sugar reported postoperative seizures in 6 of 34 patients treated with this solution. They assumed that the fixative penetrated the dura and irritated or damaged the cortex. To clarify the effect of Zenker's solution on the underlying brain, we performed bilateral parasagittal craniectomies in a group of kittens and adult cats. Zenker's solution was applied to one side and the other side served as a control. The animals were killed after periods varying from 24 hours to 2 months. We then examined the cortex under the craniectomies. There was immediate breakdown of the blood-brain barrier, as evidenced by the penetration of intravenous Evans blue. In the postoperative period investigated, an inflammatory response in the underlying brain with thickening of the arachnoid occurred. The results and implications of these experiments are presented. (Neurosurgery, 6: 45--48, 1980)"
1235063,Dooms-Goossens et al. 1980,"Follow-up study of patients with contact dermatitis caused by chromates, nickel, and cobalt","The patch test results from 1,000 patients tested with the ICDRG standard series are analyzed for positive reactions to potassium dichromate, nickel sulphate, and cobalt chloride. Nickel appears to be the most common sensitizer, especially among women, although false-negative reactions may occur if it is tested with a 2.5% concentration in yellow petrolatum. Chromate dermatitis is generally of occupational origin among men. It is also quite common among Belgian women, probably because of the widespread use of Javel (liquid bleach), containing sodium dichromate as a colouring and stabilizing agent. Positive patch test reactions to cobalt are generally accompanied by allergic reactions to nickel or chromate. Its role as a primary allergen, however, must never be overlooked. The relationship between these metals and hand and foot eczema is evaluated. The results of a follow-up questionnaire are given. More than 70% of the patients allergic to chromates or nickel continued to suffer from contact eczema after the diagnosis had been made and therapeutic measures taken.","Follow-up study of patients with contact dermatitis caused by chromates, nickel, and cobalt Abs: The patch test results from 1,000 patients tested with the ICDRG standard series are analyzed for positive reactions to potassium dichromate, nickel sulphate, and cobalt chloride. Nickel appears to be the most common sensitizer, especially among women, although false-negative reactions may occur if it is tested with a 2.5% concentration in yellow petrolatum. Chromate dermatitis is generally of occupational origin among men. It is also quite common among Belgian women, probably because of the widespread use of Javel (liquid bleach), containing sodium dichromate as a colouring and stabilizing agent. Positive patch test reactions to cobalt are generally accompanied by allergic reactions to nickel or chromate. Its role as a primary allergen, however, must never be overlooked. The relationship between these metals and hand and foot eczema is evaluated. The results of a follow-up questionnaire are given. More than 70% of the patients allergic to chromates or nickel continued to suffer from contact eczema after the diagnosis had been made and therapeutic measures taken."
1235059,Douglas et al. 1980,"Effect of lead chromate on chromosome aberration, sister-chromatid exchange and DNA damage in mammalian cells in vitro","Possible mutagenic activity of lead chromate in mammalian cells was studied using assays for chromosome aberrations and sister-chromatid exchanges in cultured human lymphocytes, and DNA fragmentation as detected by alkaline-sucrose gradient sedimentation in cultured Chinese hamster ovary (CHO) cells. Lead chromate caused dose-related increases in chromosome aberration and sister-chromatid exchange in human lymphocytes. No increase in DNA damage was observed in CHO cells, possibly due to the relative insensitivity of the CHO cells and the limited solubility of lead chromate in tissue culture medium. The mutagenicity of lead chromate in human lymphocytes appears to be entirely due to the chromate ion since chromosome aberrations were induced by potassium chromate but not lead chloride.","Effect of lead chromate on chromosome aberration, sister-chromatid exchange and DNA damage in mammalian cells in vitro Abs: Possible mutagenic activity of lead chromate in mammalian cells was studied using assays for chromosome aberrations and sister-chromatid exchanges in cultured human lymphocytes, and DNA fragmentation as detected by alkaline-sucrose gradient sedimentation in cultured Chinese hamster ovary (CHO) cells. Lead chromate caused dose-related increases in chromosome aberration and sister-chromatid exchange in human lymphocytes. No increase in DNA damage was observed in CHO cells, possibly due to the relative insensitivity of the CHO cells and the limited solubility of lead chromate in tissue culture medium. The mutagenicity of lead chromate in human lymphocytes appears to be entirely due to the chromate ion since chromosome aberrations were induced by potassium chromate but not lead chloride."
1235058,Behari and  Tandon 1980,Chelation in metal intoxication. VIII. Removal of chromium from organs of potassium chromate administered rats,"Some polyaminocarboxylic acids were examined for their ability to mobilize chromium from certain vital organs, their subcellular fractions, and blood cells of potassium chromate administered rats. Hexamethylene 1,6-diamino tetraacetic acid (TDTA), triethylene tetramine hexaacetic acid (TTHA), and ethylene diamine di (O-hydroxylphenyl acetic acid) (EDDHA) may be useful in preventing or reducing chromate toxicity. No definite relationship could be observed between the structure of the chelating agents and their chromium-removing capacity.","Chelation in metal intoxication. VIII. Removal of chromium from organs of potassium chromate administered rats Abs: Some polyaminocarboxylic acids were examined for their ability to mobilize chromium from certain vital organs, their subcellular fractions, and blood cells of potassium chromate administered rats. Hexamethylene 1,6-diamino tetraacetic acid (TDTA), triethylene tetramine hexaacetic acid (TTHA), and ethylene diamine di (O-hydroxylphenyl acetic acid) (EDDHA) may be useful in preventing or reducing chromate toxicity. No definite relationship could be observed between the structure of the chelating agents and their chromium-removing capacity."
1235057,Davis et al. 1980,Alterations of xenobiotic excretory function induced by potassium dichromate or carbon tetrachloride pretreatment,"Biliary and urinary excretory functions were determined in animals pretreated with a hepatotoxin (CCl4) or a nephrotoxin (K2Cr2O7), using polar metabolites of imipramine (PMIMP) and digoxin as models for anionic and neutral transport systems. Biliary excretion of PMIMP was decreased in CCl4-treated rats; urinary excretion was increased. Urinary and biliary excretion of digoxin were both unaffected by CCl4 treatment, but accumulation of digoxin by liver was impaired. K2Cr2O7 treatment resulted in severe nephrotoxicity accompanied by decreased urinary excretion of both model compounds. Hepatic excretion of digoxin, but not PMIMP, was increased in these animals. With minimal nephrotoxicity, urinary excretion of both compounds was unaffected. Thus the effect of toxicity on hepatic or renal excretion depends on the properties of the compounds used for excretion studies. In addition, for compounds excreted by both routes, impaired excretion by one route may be accompanied by increased excretion by the other. The extent of this compensatory mechanism may depend on several factors including the physiochemical properties of the compounds and the degree to which they are excreted by each route normally. In addition, specific cellular transport mechanisms may be important factors if involved in the excretory events.","Alterations of xenobiotic excretory function induced by potassium dichromate or carbon tetrachloride pretreatment Abs: Biliary and urinary excretory functions were determined in animals pretreated with a hepatotoxin (CCl4) or a nephrotoxin (K2Cr2O7), using polar metabolites of imipramine (PMIMP) and digoxin as models for anionic and neutral transport systems. Biliary excretion of PMIMP was decreased in CCl4-treated rats; urinary excretion was increased. Urinary and biliary excretion of digoxin were both unaffected by CCl4 treatment, but accumulation of digoxin by liver was impaired. K2Cr2O7 treatment resulted in severe nephrotoxicity accompanied by decreased urinary excretion of both model compounds. Hepatic excretion of digoxin, but not PMIMP, was increased in these animals. With minimal nephrotoxicity, urinary excretion of both compounds was unaffected. Thus the effect of toxicity on hepatic or renal excretion depends on the properties of the compounds used for excretion studies. In addition, for compounds excreted by both routes, impaired excretion by one route may be accompanied by increased excretion by the other. The extent of this compensatory mechanism may depend on several factors including the physiochemical properties of the compounds and the degree to which they are excreted by each route normally. In addition, specific cellular transport mechanisms may be important factors if involved in the excretory events."
1235056,Angelini et al. 1980,Shoe contact dermatitis,"The incidence of contact allergy was studied in a series of 165 patients with eczematous dermatitis of the feet correlated clinically with shoe contact. Positive reactions to one or more substances were recorded in 108 patients (65.4%). Among the relevant sensitizers were chromium, paraphenylenediamine, paratertiary butylphenolformaldehyde resin and nickel, while the other allergens were benzocaine, neomycin, balsam of Peru, ethylenediamine and parabens. Allergic contact dermatitis of the feet can be prevented by recognition of the allergens responsible, control of hyperhidrosis and avoidance of topical allergens.","Shoe contact dermatitis Abs: The incidence of contact allergy was studied in a series of 165 patients with eczematous dermatitis of the feet correlated clinically with shoe contact. Positive reactions to one or more substances were recorded in 108 patients (65.4%). Among the relevant sensitizers were chromium, paraphenylenediamine, paratertiary butylphenolformaldehyde resin and nickel, while the other allergens were benzocaine, neomycin, balsam of Peru, ethylenediamine and parabens. Allergic contact dermatitis of the feet can be prevented by recognition of the allergens responsible, control of hyperhidrosis and avoidance of topical allergens."
1235055,Müller 1980,Acute toxicity of potassium dichromate to Daphnia magna as a function of the water quality,,Acute toxicity of potassium dichromate to Daphnia magna as a function of the water quality Abs: 
1235054,Romaguera and  Grimalt 1980,Statistical and comparative study of 4600 patients tested in Barcelona (1973-1977),"The authors show the results obtained during the 5-year period 1973-1977 in 4600 patch tested patients in the Allergy Department of Barcelona University. The results obtained with the most common allergens (nickel sulfate, potassium dichromate, para compounds, cobalt and rubber) are studied separately. The results of testing with the allergens with a low incidence of positives are also shown. The results are compared with those published by the NACDG on 1200 patients and by Brun in Geneva on 1000 patients; 5.02% of the tested patients showed sensitization to benzidine.","Statistical and comparative study of 4600 patients tested in Barcelona (1973-1977) Abs: The authors show the results obtained during the 5-year period 1973-1977 in 4600 patch tested patients in the Allergy Department of Barcelona University. The results obtained with the most common allergens (nickel sulfate, potassium dichromate, para compounds, cobalt and rubber) are studied separately. The results of testing with the allergens with a low incidence of positives are also shown. The results are compared with those published by the NACDG on 1200 patients and by Brun in Geneva on 1000 patients; 5.02% of the tested patients showed sensitization to benzidine."
1235051,Abraham et al. 1980,The effect of chromium on established atherosclerotic plaques in rabbits,"Twenty-three rabbits were fed for 8 weeks with standard diet to which was added a 1.5% cholesterol supplement. After this the cholesterol supplement was discontinued, but 11 rabbits received a daily intraperitoneal injection of 20 micrograms of potassium chromate while the remaining 12 received distilled water. The aortas were examined after a further 30 weeks; their mean weight per unit length was 1.27 g (SE +/- 0.17) in the control group and 0.81 g (SE +/- 0.08) in the chromium treated group (t = 2.36; P &lt; 0.05). The percentage area of intimal surface covered by plaques was 94.8% (SE +/- 1.7) and 62.6% (SE +/- 10.4), respectively (t = 3.53; P &lt; 0.005), and the total cholesterol content per unit length of aorta was 729 mg/100 ml (SE +/- 44.0) and 457.8 mg/100 ml (SE +/- 117.1), respectively (t = 23; P &lt; 0.05). The results show a significant effect of chromium on the regression of cholesterol-induced atherosclerotic plaques in rabbits.","The effect of chromium on established atherosclerotic plaques in rabbits Abs: Twenty-three rabbits were fed for 8 weeks with standard diet to which was added a 1.5% cholesterol supplement. After this the cholesterol supplement was discontinued, but 11 rabbits received a daily intraperitoneal injection of 20 micrograms of potassium chromate while the remaining 12 received distilled water. The aortas were examined after a further 30 weeks; their mean weight per unit length was 1.27 g (SE +/- 0.17) in the control group and 0.81 g (SE +/- 0.08) in the chromium treated group (t = 2.36; P &lt; 0.05). The percentage area of intimal surface covered by plaques was 94.8% (SE +/- 1.7) and 62.6% (SE +/- 10.4), respectively (t = 3.53; P &lt; 0.005), and the total cholesterol content per unit length of aorta was 729 mg/100 ml (SE +/- 44.0) and 457.8 mg/100 ml (SE +/- 117.1), respectively (t = 23; P &lt; 0.05). The results show a significant effect of chromium on the regression of cholesterol-induced atherosclerotic plaques in rabbits."
1235050,Slomiany et al. 1980,Complex fucolipids of hog gastric mucosa. Structure of the ceramide eikosahexoside,"The structure of a complex fucolipid from hog gastric mucosa containing twenty sugar residues and exhibiting blood-group (A + H) activity has been investigated. Based on the results of immunological assays, partial acid hydrolysis, sequential degradation with specific exoglycosidases, oxidation with periodate and chromium trioxide, and permethylation analysis, we suggest that the carbohydrate chain of this fucolipid contains four termini. One of the termini bears beta Gal1 leads to 4 beta GlcNAc disaccharide, two bear blood-group A determinant and one bears H determinant. Two of the branches, terminated by beta Gal1 leads to 4 beta GlcNAc and blood-group A determinant, and two terminated by blood-group A and H determinants, are linked through beta Gal1 leads to 4 beta GlcNAc1 leads to 3/6 and beta Gal1 leads to 4 beta GlcNAc1 leads to 4 beta GlcNAc1 leads to 3/6 to the galactose residue adjacent to glucosylceramide core.","Complex fucolipids of hog gastric mucosa. Structure of the ceramide eikosahexoside Abs: The structure of a complex fucolipid from hog gastric mucosa containing twenty sugar residues and exhibiting blood-group (A + H) activity has been investigated. Based on the results of immunological assays, partial acid hydrolysis, sequential degradation with specific exoglycosidases, oxidation with periodate and chromium trioxide, and permethylation analysis, we suggest that the carbohydrate chain of this fucolipid contains four termini. One of the termini bears beta Gal1 leads to 4 beta GlcNAc disaccharide, two bear blood-group A determinant and one bears H determinant. Two of the branches, terminated by beta Gal1 leads to 4 beta GlcNAc and blood-group A determinant, and two terminated by blood-group A and H determinants, are linked through beta Gal1 leads to 4 beta GlcNAc1 leads to 3/6 and beta Gal1 leads to 4 beta GlcNAc1 leads to 4 beta GlcNAc1 leads to 3/6 to the galactose residue adjacent to glucosylceramide core."
1235049,Riva et al. 1981,Lethal potassium dichromate and whitening (Blankophor) exposure of gold fish (Carassius auratus); chromium levels in gills,"The mortality and the gill Cr accumulation was determined for potassium dichromate. The influence of pH, temperature and the concomitant presence of a fluorescent whitening agent (Blankophor) was studied. An increase in mortality was related to temperature. A small influence of both pH and whitening was observed. Cr in the tank produces accumulation of the metal by gills. This accumulation is not related to dose or temperature. Some small effect of pH and a clear effect of the whitening was found. Cr in gills of moribund fish (dead) was higher than in live but identically treated fish.","Lethal potassium dichromate and whitening (Blankophor) exposure of gold fish (Carassius auratus); chromium levels in gills Abs: The mortality and the gill Cr accumulation was determined for potassium dichromate. The influence of pH, temperature and the concomitant presence of a fluorescent whitening agent (Blankophor) was studied. An increase in mortality was related to temperature. A small influence of both pH and whitening was observed. Cr in the tank produces accumulation of the metal by gills. This accumulation is not related to dose or temperature. Some small effect of pH and a clear effect of the whitening was found. Cr in gills of moribund fish (dead) was higher than in live but identically treated fish."
1235046,Bernal et al. 1981,A rapid colorimetric assay for dry weight,"A rapid, precise colorimetric method for the determination of dry weight in the range 100 1,000 micro grams is reported. The method involves reacting biological materials with an acid solution of dichromate for 20 min at 92 degrees C followed by determination of the optical density at 630 nm of the product formed. The principal advantage of the dichromate method over the standard weight method are: 1) The shorter time required for determination, 2) its greater sensitivity, exactitude and precision using standard laboratory equipment, 3) the method is insensitive to inorganic compounds and therefore can be applied to tissue homogenates prepared in inorganic solutions. The only disadvantage of the method seems to be that dichromate will react specifically with carbon containing groups and therefore the participation of nitrogen, or other elements, in the composition of the biological material, will give proportionately lower absorbances.","A rapid colorimetric assay for dry weight Abs: A rapid, precise colorimetric method for the determination of dry weight in the range 100 1,000 micro grams is reported. The method involves reacting biological materials with an acid solution of dichromate for 20 min at 92 degrees C followed by determination of the optical density at 630 nm of the product formed. The principal advantage of the dichromate method over the standard weight method are: 1) The shorter time required for determination, 2) its greater sensitivity, exactitude and precision using standard laboratory equipment, 3) the method is insensitive to inorganic compounds and therefore can be applied to tissue homogenates prepared in inorganic solutions. The only disadvantage of the method seems to be that dichromate will react specifically with carbon containing groups and therefore the participation of nitrogen, or other elements, in the composition of the biological material, will give proportionately lower absorbances."
1235045,Olczak and  Chmielnicka 1981,[Biochemical indicators of toxic kidney damage],,[Biochemical indicators of toxic kidney damage] Abs: 
1235043,Hénocq and  Gaillard 1981,Cutaneous basophil hypersensitivity in atopic dermatitis,"The infiltration by basophils into delayed hypersensitivity skin test sites was examined in patients with atopic dermatitis, contact dermatitis and in normal healthy persons. Atopic dermatitis patients, with large amounts of IgE, injected intradermally with staphylococcal antigens showed reactions that were more transient and erythematous than those of normal persons. On histological examination there were numerous, degranulating basophils among the perivascular mononuclear cells. Normal persons, with small amounts of IgE showed typical mononuclear cell infiltration and few basophils. Patients with contact dermatitis, one with much IgE, responded to patch tests to potassium dichromate or to nickel sulphate by delayed type reactions, but on histology, two of the four patients showed a significant infiltration by basophils. It is considered that the erythematous response to the antigen in atopic dermatitis patients is related to the basophil infiltration.","Cutaneous basophil hypersensitivity in atopic dermatitis Abs: The infiltration by basophils into delayed hypersensitivity skin test sites was examined in patients with atopic dermatitis, contact dermatitis and in normal healthy persons. Atopic dermatitis patients, with large amounts of IgE, injected intradermally with staphylococcal antigens showed reactions that were more transient and erythematous than those of normal persons. On histological examination there were numerous, degranulating basophils among the perivascular mononuclear cells. Normal persons, with small amounts of IgE showed typical mononuclear cell infiltration and few basophils. Patients with contact dermatitis, one with much IgE, responded to patch tests to potassium dichromate or to nickel sulphate by delayed type reactions, but on histology, two of the four patients showed a significant infiltration by basophils. It is considered that the erythematous response to the antigen in atopic dermatitis patients is related to the basophil infiltration."
1235042,Ngaha 1981,Renal effects of potassium dichromate in the rat: comparison of urinary enzyme excretion with corresponding tissue patterns,"1. The administration of potassium dichromate to rats caused significant elevation of urine output, urinary proteins and some urinary euzymes. 2. Kidney and liver enzyme levels in the treated rats were correspondingly reduced suggesting that potassium dichromate is toxic to both the liver and the kidney. 3. The use of urine volume, urinary protein and urinary enzyme changes could be useful in detecting the nature of damage caused by some toxic chemical compounds.","Renal effects of potassium dichromate in the rat: comparison of urinary enzyme excretion with corresponding tissue patterns Abs: 1. The administration of potassium dichromate to rats caused significant elevation of urine output, urinary proteins and some urinary euzymes. 2. Kidney and liver enzyme levels in the treated rats were correspondingly reduced suggesting that potassium dichromate is toxic to both the liver and the kidney. 3. The use of urine volume, urinary protein and urinary enzyme changes could be useful in detecting the nature of damage caused by some toxic chemical compounds."
1235040,Davis and  Winlove 1981,Uptake of low molecular weight materials in an in situ preparation of the rabbit thoracic aorta,"1. An in situ preparation of the rabbit thoracic aorta is described in which the integrity of the intimal endothelium is shown to be preserved. An extensive system of vasa vasorum and lymphatic vessels distributed throughout the adventitia, but not penetrating the media, are demonstrated using resin casts and lead chromate precipitation techniques and are shown to be patent in this preparation. 2. The role of the vasa vasorum in the medial uptake of low molecular weight materials is investigated as a function of luminal hydrostatic pressure and perfusion time. Comparison of uptake in vessels with and without patent vasa vasorum indicates that at physiological pressures medial uptake of 125I ions is dominated by entry from the adventitial surface. Analysis of the transmural distribution of 125I demonstrates that iodide is not retarded at the endothelial surface but a barrier exists within the intima which is tentatively identified as the internal elastic lamina. Qualitative studies show that Patent Blue V whose coloured anion has a molecular weight of 500 is able, at longer perfusion times, to penetrate this barrier. There is no circumferential variation in intimal uptake, but in contrast, adventitial uptake is rather patchy and generally more intense on the dorsal surfaces of the aorta. 3. Iodide transport across the intimal surface is argued to be predominantly diffusive in short duration experiments with an effective diffusion coefficient of (1.6 +/- 0.9) X 10(-6) cm2 min-1.","Uptake of low molecular weight materials in an in situ preparation of the rabbit thoracic aorta Abs: 1. An in situ preparation of the rabbit thoracic aorta is described in which the integrity of the intimal endothelium is shown to be preserved. An extensive system of vasa vasorum and lymphatic vessels distributed throughout the adventitia, but not penetrating the media, are demonstrated using resin casts and lead chromate precipitation techniques and are shown to be patent in this preparation. 2. The role of the vasa vasorum in the medial uptake of low molecular weight materials is investigated as a function of luminal hydrostatic pressure and perfusion time. Comparison of uptake in vessels with and without patent vasa vasorum indicates that at physiological pressures medial uptake of 125I ions is dominated by entry from the adventitial surface. Analysis of the transmural distribution of 125I demonstrates that iodide is not retarded at the endothelial surface but a barrier exists within the intima which is tentatively identified as the internal elastic lamina. Qualitative studies show that Patent Blue V whose coloured anion has a molecular weight of 500 is able, at longer perfusion times, to penetrate this barrier. There is no circumferential variation in intimal uptake, but in contrast, adventitial uptake is rather patchy and generally more intense on the dorsal surfaces of the aorta. 3. Iodide transport across the intimal surface is argued to be predominantly diffusive in short duration experiments with an effective diffusion coefficient of (1.6 +/- 0.9) X 10(-6) cm2 min-1."
1235039,Moon and  Bemrick 1981,Fecal transmission of calf cryptosporidia between calves and pigs,"All of 17 calves 1 to 21 days old and 23 of 24 1-day-old pigs inoculated orally with calf feces containing cryptosporidia oocysts became infected with cryptosporidia. Infectivity was maintained by discontinuous passage in calves, with storage in potassium dichromate solution for up to eight weeks between passages. Cryptosporidia shed in calf feces also were infectious for calves directly after collection, without storage in potassium dichromate (two calves). Infected calves and pigs shed cryptosporidia oocysts in their feces for several days (mean of 10 days). Those necropsied at this stage of infection had many cryptosporidia and partial atrophy of villi in their ilea. All of the pigs and 60% of the calves also had cryptosporidia infections in their large intestines at this stage. It was concluded that calf cryptosporidia can be transmitted via feces to calves and to pigs.","Fecal transmission of calf cryptosporidia between calves and pigs Abs: All of 17 calves 1 to 21 days old and 23 of 24 1-day-old pigs inoculated orally with calf feces containing cryptosporidia oocysts became infected with cryptosporidia. Infectivity was maintained by discontinuous passage in calves, with storage in potassium dichromate solution for up to eight weeks between passages. Cryptosporidia shed in calf feces also were infectious for calves directly after collection, without storage in potassium dichromate (two calves). Infected calves and pigs shed cryptosporidia oocysts in their feces for several days (mean of 10 days). Those necropsied at this stage of infection had many cryptosporidia and partial atrophy of villi in their ilea. All of the pigs and 60% of the calves also had cryptosporidia infections in their large intestines at this stage. It was concluded that calf cryptosporidia can be transmitted via feces to calves and to pigs."
1235038,Sriramam et al. 1981,"A new and rapid titration of antimony(III) with potassium dichromate, with iron(II) as inductor","The optimum conditions for the titration of antimony(III) with dichromate, and diphenyl-aminesulphonic acid as indicator, have been established. No iodine catalyst is used; the analytical reaction is based on an induced reaction with iron(II) as inductor. The titration can be done as easily as an iron(II) titration and the end-point is equally sharp. Titrations are possible with 0.01N solutions.","A new and rapid titration of antimony(III) with potassium dichromate, with iron(II) as inductor Abs: The optimum conditions for the titration of antimony(III) with dichromate, and diphenyl-aminesulphonic acid as indicator, have been established. No iodine catalyst is used; the analytical reaction is based on an induced reaction with iron(II) as inductor. The titration can be done as easily as an iron(II) titration and the end-point is equally sharp. Titrations are possible with 0.01N solutions."
1235037,Mueller and  Lang 1981,Use of potassium dichromate as a surrogate standard for beta-carotene determination,,Use of potassium dichromate as a surrogate standard for beta-carotene determination Abs: 
1235036,Franke et al. 1981,Inhibition of oxygen utilization by substances in combination,"Measurement of concentrations at which substances in combination become toxic is complex, especially if quantitative definition of additive, antagonistic or synergistic toxicity is desired. Using inhibition of oxygen utilized by aerobic micro-organisms in their metabolism of a standard substrate, seven chemicals were tested singly and in eight combinations for their graded toxic effects. In two of the experimental investigations the combined effects of three chemicals were determined. By comparing summations of the measured effects of the chemicals tested singly with similar results from testing the toxicity of actual combinations of the chemicals in solution it was found that the actual inhibitions of the oxygen utilization were essentially the same as predicted inhibitions over a range of aqueous concentrations. Statistical analysis of all combinations tested indicated the effects to be additive. Neither synergism nor antagonism was shown. The pure compounds tested were: mercuric chloride, potassium cyanide, nickel chloride, potassium chromate, copper sulfate, phenol and nitrobenzene. Although the toxicity of each chemical has been quite extensively studied, results regarding combined effects are relatively few. The methods presented here are applicable to many compounds in combination.","Inhibition of oxygen utilization by substances in combination Abs: Measurement of concentrations at which substances in combination become toxic is complex, especially if quantitative definition of additive, antagonistic or synergistic toxicity is desired. Using inhibition of oxygen utilized by aerobic micro-organisms in their metabolism of a standard substrate, seven chemicals were tested singly and in eight combinations for their graded toxic effects. In two of the experimental investigations the combined effects of three chemicals were determined. By comparing summations of the measured effects of the chemicals tested singly with similar results from testing the toxicity of actual combinations of the chemicals in solution it was found that the actual inhibitions of the oxygen utilization were essentially the same as predicted inhibitions over a range of aqueous concentrations. Statistical analysis of all combinations tested indicated the effects to be additive. Neither synergism nor antagonism was shown. The pure compounds tested were: mercuric chloride, potassium cyanide, nickel chloride, potassium chromate, copper sulfate, phenol and nitrobenzene. Although the toxicity of each chemical has been quite extensively studied, results regarding combined effects are relatively few. The methods presented here are applicable to many compounds in combination."
1235032,Appel et al. 1981,Studies on the mechanism of non-oliguric experimental acute renal failure,"Although acute renal failure, caused either by renal ischemia or nephrotoxic agents, is usually characterized by oliguria, a severe fall in glomerular filtration rate, and a fall in renal blood flow, some patients and experimental models display a non-oliguric pattern of renal injury. The present study was designed to evaluate the mechanism of preservation of high urinary flow rate under this condition. Following the administration of the aminoglycoside gentamicin to rats for five days, a decrease in concentrating ability was demonstrated, caused by impaired vasopressin-mediated water transport. Further treatment resulted in a fall in Cin to 15 percent of control, although RBF was reduced to only 67 percent of control, and urine flow rate rose above control levels. Induction of acute and renal failure with dichromate was associated with variable high or low urinary flow rates according to pre-injury intake of sodium. Urine volume correlated directly with cortical blood flow. These data suggest that the non-oliguric pattern of acute renal injury is caused by preservation of cortical perfusion in the setting of severe tubular injury.","Studies on the mechanism of non-oliguric experimental acute renal failure Abs: Although acute renal failure, caused either by renal ischemia or nephrotoxic agents, is usually characterized by oliguria, a severe fall in glomerular filtration rate, and a fall in renal blood flow, some patients and experimental models display a non-oliguric pattern of renal injury. The present study was designed to evaluate the mechanism of preservation of high urinary flow rate under this condition. Following the administration of the aminoglycoside gentamicin to rats for five days, a decrease in concentrating ability was demonstrated, caused by impaired vasopressin-mediated water transport. Further treatment resulted in a fall in Cin to 15 percent of control, although RBF was reduced to only 67 percent of control, and urine flow rate rose above control levels. Induction of acute and renal failure with dichromate was associated with variable high or low urinary flow rates according to pre-injury intake of sodium. Urine volume correlated directly with cortical blood flow. These data suggest that the non-oliguric pattern of acute renal injury is caused by preservation of cortical perfusion in the setting of severe tubular injury."
1235031,Sukanto et al. 1981,Influence of topically applied corticosteroids on patch test reactions,"Four commercially available corticosteroid preparations were assayed for their capacity to suppress patch test reactions with contact allergens (nickel sulfate, nitrofuralum, potassium dichromate, epoxy resin, wood tars and Maneb) in sensitized individuals (n=14). Beta-methasone valerate, betamethasone dipropionate, hydrocortisone-17-butyrate and triamcinolone acetonide (0.05-0.7% solutions in isopropanol or ethanol) were applied under occlusion in amounts of 0.01, 0.02 and 0.04 ml, respectively. Patch tests were performed on the pretreated skin sites. The patches were removed 24 h after application and the reactions were read 15 min and 24 h later. The intensity of the reactions and the size of the infiltrated areas of the pretreated sites were measured and compared with those of a control patch test. Topical application of corticosteroids was found to have a suppressive effect both on the intensity as well as on the size of the epicutaneous reactions. No marked difference in the suppression effect of the four corticosteroids could be observed.","Influence of topically applied corticosteroids on patch test reactions Abs: Four commercially available corticosteroid preparations were assayed for their capacity to suppress patch test reactions with contact allergens (nickel sulfate, nitrofuralum, potassium dichromate, epoxy resin, wood tars and Maneb) in sensitized individuals (n=14). Beta-methasone valerate, betamethasone dipropionate, hydrocortisone-17-butyrate and triamcinolone acetonide (0.05-0.7% solutions in isopropanol or ethanol) were applied under occlusion in amounts of 0.01, 0.02 and 0.04 ml, respectively. Patch tests were performed on the pretreated skin sites. The patches were removed 24 h after application and the reactions were read 15 min and 24 h later. The intensity of the reactions and the size of the infiltrated areas of the pretreated sites were measured and compared with those of a control patch test. Topical application of corticosteroids was found to have a suppressive effect both on the intensity as well as on the size of the epicutaneous reactions. No marked difference in the suppression effect of the four corticosteroids could be observed."
1235030,Seeger and  Wachter 1981,Rubescenslysin and phallolysin release marker molecules from phospholipid cholesterol liposomes,"Multilamellar liposomes were prepared from phospholipid, cholesterol and dicetyl phosphate and marked with potassium chromate or with glucose. They were treated with 0.5--50 haemolytic units (HU)/ml of rubescenslysin from Amanita rubescens or of phallolysin from Amanita phalloides. Rubescenslysin caused a dose-dependent release of marker molecules from phosphatidylcholine and from sphingomyelin liposomes. A statistically significant marker leakage was caused by 0.5--1 HU/ml from liposomes prepared from sphingomyelin, phosphatidylcholine from egg yolk, and among the synthetic phosphatidylcholines from distearoyl greater than dipalmitoyl greater than dioleoyl phosphatidylcholine. With the lysin concentrations tested, at the best 50% of total markers were released from sphingomyelin liposomes and 75--95% from phosphatidylcholine liposomes. Also phallolysin released marker molecules from phosphatidylcholine liposomes; statistically significant amounts were released by 0.5 HU/ml from egg yolk phosphatidylcholine and from dipalmitoyl congruent to distearoyl greater than dioleoyl phosphatidylcholine liposomes; 60--90% of maximum release was achieved at the best. However, liposomes prepared from (bovine) sphingomyelin were resistant to phallolysin; even with 50 HU/ml no leakage of markers was observed. Heat-inactivated rubescenslysin, heat-inactivated phallolysin and human serum albumin failed to release markers. Our results lead to the conclusion that both, rubescenslysin and phallolysin, interact with membrane phospholipids, phallolysin showing a higher degree of specificity.","Rubescenslysin and phallolysin release marker molecules from phospholipid cholesterol liposomes Abs: Multilamellar liposomes were prepared from phospholipid, cholesterol and dicetyl phosphate and marked with potassium chromate or with glucose. They were treated with 0.5--50 haemolytic units (HU)/ml of rubescenslysin from Amanita rubescens or of phallolysin from Amanita phalloides. Rubescenslysin caused a dose-dependent release of marker molecules from phosphatidylcholine and from sphingomyelin liposomes. A statistically significant marker leakage was caused by 0.5--1 HU/ml from liposomes prepared from sphingomyelin, phosphatidylcholine from egg yolk, and among the synthetic phosphatidylcholines from distearoyl greater than dipalmitoyl greater than dioleoyl phosphatidylcholine. With the lysin concentrations tested, at the best 50% of total markers were released from sphingomyelin liposomes and 75--95% from phosphatidylcholine liposomes. Also phallolysin released marker molecules from phosphatidylcholine liposomes; statistically significant amounts were released by 0.5 HU/ml from egg yolk phosphatidylcholine and from dipalmitoyl congruent to distearoyl greater than dioleoyl phosphatidylcholine liposomes; 60--90% of maximum release was achieved at the best. However, liposomes prepared from (bovine) sphingomyelin were resistant to phallolysin; even with 50 HU/ml no leakage of markers was observed. Heat-inactivated rubescenslysin, heat-inactivated phallolysin and human serum albumin failed to release markers. Our results lead to the conclusion that both, rubescenslysin and phallolysin, interact with membrane phospholipids, phallolysin showing a higher degree of specificity."
1235029,Greuter et al. 1981,Lack of sensitivity and specificity of the renal clearance of amylase/clearance of inulin ratio in experimental acute rat pancreatitis with a study on the renal handling of amylase,"As there are controversies about the specificity and the sensitivity of the amylase clearance/inulin clearance ratio (Cam/Cin) in the diagnosis of pancreatitis, this ratio has been calculated: (a) in rats with induced pancreatitis with histologically proven lesions; (b) in toxic induced tubulopathy rats with lesions demonstrated histologically and biologically (enzymuria). Hyperamylasaemia was found in 86% of the pancreatitis rats at 24 h, 50% at 48 h and 25% at 60 h. The ratio Cam/Cin was elevated above 2 SD of the control values among 14% of the rats at 24 h, 50% at 48 h and 25% at 60 h. There were no changes in enzyme elimination rates in the urine as compared to control values. Renal histology remained normal. Histological scores expressing a severe haemorrhagic pancreatitis were identical at 24, 48 ad 60 h. In toxic induced tubulopathy rats, amylasaemia remained normal. but the Cam/Cin ratio only increased when the glomerular filtration rate was diminished by 90%. The diagnosis could only be made by hyperamylasaemia in 50% of the histologically proven pancreatitis in the rat. The use of the ratio Cam/Cin does not increase the frequency of a correct diagnosis. Finally, amylase must be only filtered by the kidney as no tubular enzymes appeared in the urine of pancreatitis rats. Furthermore, this ratio is not specific for pancreatitis as it could be elevated in other pathologic states such as severe renal failure.","Lack of sensitivity and specificity of the renal clearance of amylase/clearance of inulin ratio in experimental acute rat pancreatitis with a study on the renal handling of amylase Abs: As there are controversies about the specificity and the sensitivity of the amylase clearance/inulin clearance ratio (Cam/Cin) in the diagnosis of pancreatitis, this ratio has been calculated: (a) in rats with induced pancreatitis with histologically proven lesions; (b) in toxic induced tubulopathy rats with lesions demonstrated histologically and biologically (enzymuria). Hyperamylasaemia was found in 86% of the pancreatitis rats at 24 h, 50% at 48 h and 25% at 60 h. The ratio Cam/Cin was elevated above 2 SD of the control values among 14% of the rats at 24 h, 50% at 48 h and 25% at 60 h. There were no changes in enzyme elimination rates in the urine as compared to control values. Renal histology remained normal. Histological scores expressing a severe haemorrhagic pancreatitis were identical at 24, 48 ad 60 h. In toxic induced tubulopathy rats, amylasaemia remained normal. but the Cam/Cin ratio only increased when the glomerular filtration rate was diminished by 90%. The diagnosis could only be made by hyperamylasaemia in 50% of the histologically proven pancreatitis in the rat. The use of the ratio Cam/Cin does not increase the frequency of a correct diagnosis. Finally, amylase must be only filtered by the kidney as no tubular enzymes appeared in the urine of pancreatitis rats. Furthermore, this ratio is not specific for pancreatitis as it could be elevated in other pathologic states such as severe renal failure."
1235028,Levis and  Majone 1981,Cytotoxic and clastogenic effects of soluble and insoluble compounds containing hexavalent and trivalent chromium,"Cr(III) and Cr(VI) compounds of varying solubilities have been tested in vitro for their ability to inhibit cell growth and nucleic acid and protein syntheses in BHK cells, to induce alterations in the mitotic cycle in HEp cells, and to increase the frequency of chromosomal aberrations and sister chromatid exchanges (SCE) in CHO cells. All Cr(VI) compounds, and particularly those containing soluble Cr(VI), such as potassium dichromate and zinc yellow, differentially inhibit macromolecular syntheses in BKH cells, that of DNA being always the most affected. Among Cr(III) compounds, which generally have very low cytotoxicity, chromite is particularly active, and inhibits cell growth and DNA synthesis even more than the poorly soluble Cr(VI) compounds. Preincubation in growth medium, with or without metabolizing cell cultures, solubilizes considerable amounts of Cr(VI) from zinc yellow and chromite, but significant amounts are also obtained from the most insoluble Cr(VI) pigments. When BHK cells are treated with such preincubated solutions, reduction of soluble Cr(VI) to Cr(III) by cell metabolites is seen with all Cr(VI) compounds, accompanied by decreased cytotoxicity. The same differences between Cr(VI) and Cr(III) compounds apply to the cytotoxic effects on mitosis of HEp cells and the clastogenic effects on CHO cells. The activity of chromite, the only Cr(III) pigment capable of significantly increasing the frequency of SCE, is due to contamination with soluble Cr(VI). In contrast to the very low cytotoxicity of Cr(III), much higher chromium levels are detected in the cells incubated with soluble Cr(III) than with the same concentrations of soluble Cr(VI). 50% and 75% of chromium accumulated in the cells during treatments with Cr(VI) and Cr(III) respectively remains firmly bound to the cells, even when they are incubated for up to 48 h in normal growth medium. Chromium accumulated in the cells after treatment with Cr(III) is most probably bound to the cell membrane, whereas some of the Cr(VI) is transported through the cell membrane and reduced in the cell nucleus. The results of the present investigation are in agreement with those obtained with the same Cr(VI) and Cr(III) compounds in mutagenicity assays in bacteria and carcinogenicity tests in rodents. A re-evaluation of the mechanisms of chromium carcinogenisis is proposed.","Cytotoxic and clastogenic effects of soluble and insoluble compounds containing hexavalent and trivalent chromium Abs: Cr(III) and Cr(VI) compounds of varying solubilities have been tested in vitro for their ability to inhibit cell growth and nucleic acid and protein syntheses in BHK cells, to induce alterations in the mitotic cycle in HEp cells, and to increase the frequency of chromosomal aberrations and sister chromatid exchanges (SCE) in CHO cells. All Cr(VI) compounds, and particularly those containing soluble Cr(VI), such as potassium dichromate and zinc yellow, differentially inhibit macromolecular syntheses in BKH cells, that of DNA being always the most affected. Among Cr(III) compounds, which generally have very low cytotoxicity, chromite is particularly active, and inhibits cell growth and DNA synthesis even more than the poorly soluble Cr(VI) compounds. Preincubation in growth medium, with or without metabolizing cell cultures, solubilizes considerable amounts of Cr(VI) from zinc yellow and chromite, but significant amounts are also obtained from the most insoluble Cr(VI) pigments. When BHK cells are treated with such preincubated solutions, reduction of soluble Cr(VI) to Cr(III) by cell metabolites is seen with all Cr(VI) compounds, accompanied by decreased cytotoxicity. The same differences between Cr(VI) and Cr(III) compounds apply to the cytotoxic effects on mitosis of HEp cells and the clastogenic effects on CHO cells. The activity of chromite, the only Cr(III) pigment capable of significantly increasing the frequency of SCE, is due to contamination with soluble Cr(VI). In contrast to the very low cytotoxicity of Cr(III), much higher chromium levels are detected in the cells incubated with soluble Cr(III) than with the same concentrations of soluble Cr(VI). 50% and 75% of chromium accumulated in the cells during treatments with Cr(VI) and Cr(III) respectively remains firmly bound to the cells, even when they are incubated for up to 48 h in normal growth medium. Chromium accumulated in the cells after treatment with Cr(III) is most probably bound to the cell membrane, whereas some of the Cr(VI) is transported through the cell membrane and reduced in the cell nucleus. The results of the present investigation are in agreement with those obtained with the same Cr(VI) and Cr(III) compounds in mutagenicity assays in bacteria and carcinogenicity tests in rodents. A re-evaluation of the mechanisms of chromium carcinogenisis is proposed."
1235027,Calnan 1981,Keloid formation after patch tests,,Keloid formation after patch tests Abs: 
1235025,Dohoo et al. 1981,The effects of storage and method of fixation on somatic cell counts in bovine milk,"Fresh milk samples and potassium dichromate preserved milk samples were stored at both ambient, approximately 21 degree C, and refrigerator temperatures, 3-5 degree C, for varying lengths of time before somatic cell counts were performed on an electronic particle counter. Fresh milk samples stored at ambient temperatures became unacceptable for somatic cell counting by 16 hours while those stored in the refrigerator were acceptable for up to three days. Once dichromate had been added to the milk no difference in cell counts attributable to temperature of storage were detected and there was very little change with time up to 14 days. On the average the addition of the dichromate elevated the cell counts/mL. As well a method of rapid fixation of milk involving the addition of glutaraldehyde prior to counting was evaluated. In fresh milk samples the use of glutaraldehyde as a fixative required adjustment of the threshold setting on the cell counter in order to produce results comparable to those obtained from formalin fixed samples. With dichromate preserved milk samples, glutaraldehyde fixation generally elevated the cell counts but the results were variable.","The effects of storage and method of fixation on somatic cell counts in bovine milk Abs: Fresh milk samples and potassium dichromate preserved milk samples were stored at both ambient, approximately 21 degree C, and refrigerator temperatures, 3-5 degree C, for varying lengths of time before somatic cell counts were performed on an electronic particle counter. Fresh milk samples stored at ambient temperatures became unacceptable for somatic cell counting by 16 hours while those stored in the refrigerator were acceptable for up to three days. Once dichromate had been added to the milk no difference in cell counts attributable to temperature of storage were detected and there was very little change with time up to 14 days. On the average the addition of the dichromate elevated the cell counts/mL. As well a method of rapid fixation of milk involving the addition of glutaraldehyde prior to counting was evaluated. In fresh milk samples the use of glutaraldehyde as a fixative required adjustment of the threshold setting on the cell counter in order to produce results comparable to those obtained from formalin fixed samples. With dichromate preserved milk samples, glutaraldehyde fixation generally elevated the cell counts but the results were variable."
1235024,Ferguson 1981,Lead chromate,,Lead chromate Abs: 
1235023,Nethercott 1981,Airborne irritant contact dermatitis due to sewage sludge,An outbreaks of cases of airborne irritant contact dermatitis developed among incinerator workers employed in a sewage treatment facility. Contamination of the workplace and workers' clothing by sludge from the interstices of an incinerator exhaust fan proved to be the cause of the problem. The irritancy of the sludge was determined by tests in rabbits. There was no recurrence of the problem after the institution of hygienic measures designed to control contact with the sludge during subsequent fan maintenance procedures.,Airborne irritant contact dermatitis due to sewage sludge Abs: An outbreaks of cases of airborne irritant contact dermatitis developed among incinerator workers employed in a sewage treatment facility. Contamination of the workplace and workers' clothing by sludge from the interstices of an incinerator exhaust fan proved to be the cause of the problem. The irritancy of the sludge was determined by tests in rabbits. There was no recurrence of the problem after the institution of hygienic measures designed to control contact with the sludge during subsequent fan maintenance procedures.
1235022,Mclaren 1981,Routine kilogray dosimetry with dichromate solutions,,Routine kilogray dosimetry with dichromate solutions Abs: 
1235021,Fukuda et al. 1981,Isolation and structural studies of the neutral oligosaccharide units from bovine glycophorin,"The O-glycosidically linked carbohydrate units of glycophorin from bovine erythrocyte membranes were released as reduced oligosaccharides by alkaline borohydride treatment. These oligosaccharides were separated by ion-exchange chromatography followed by gel filtration. Three oligosaccharides, a penta- a hepta- and a decasaccharide were obtained as the major components from the neutral fraction, and seven fractions were separated from the acidic fractions. All of the fractions were found to contain galactose and N-acetylglucosamine in variable amounts, as well as N-acetylgalactosaminitol. Studies of the neutral oligosaccharides by methylation analyses, nitrous acid deamination and Smith degradation, indicated the structure of the pentasaccharide to be Gal(1 leads to 3)Gal(1 leads to 4)GlcNAc(1 leads to 3)GalNAcol and that of the heptasaccharide to be Gal(1 leads to 3)Gal(1 leads to 4)GlcNAc(1 leads to 3)Gal(1 leads to 4)GlcNAc(1 leads to 3)Gal(1 leads to 3)GalNAcol. The highest molecular weight fraction, decasaccharide in the neutral fraction had a branching point at C-6 of a galactose residue.","Isolation and structural studies of the neutral oligosaccharide units from bovine glycophorin Abs: The O-glycosidically linked carbohydrate units of glycophorin from bovine erythrocyte membranes were released as reduced oligosaccharides by alkaline borohydride treatment. These oligosaccharides were separated by ion-exchange chromatography followed by gel filtration. Three oligosaccharides, a penta- a hepta- and a decasaccharide were obtained as the major components from the neutral fraction, and seven fractions were separated from the acidic fractions. All of the fractions were found to contain galactose and N-acetylglucosamine in variable amounts, as well as N-acetylgalactosaminitol. Studies of the neutral oligosaccharides by methylation analyses, nitrous acid deamination and Smith degradation, indicated the structure of the pentasaccharide to be Gal(1 leads to 3)Gal(1 leads to 4)GlcNAc(1 leads to 3)GalNAcol and that of the heptasaccharide to be Gal(1 leads to 3)Gal(1 leads to 4)GlcNAc(1 leads to 3)Gal(1 leads to 4)GlcNAc(1 leads to 3)Gal(1 leads to 3)GalNAcol. The highest molecular weight fraction, decasaccharide in the neutral fraction had a branching point at C-6 of a galactose residue."
1235019,Suzuki and  Fukazawa 1982,Immunochemical characterization of Candida albicans cell wall antigens: specific determinant of Candida albicans serotype A mannan,"We investigated the chemical structure of the specific determinant in the mannan of Candida albicans M-1012 (serotype A) strain. Acetolysis of the mannan, obtained by alkali extraction and purified as the copper complex, gave mannose and six oligosaccharides (from di- to hexasaccharide) and a small amount of a heptasaccharide. We examined the inhibition by these oligosaccharides up to hexaose of the precipitin reaction between anti-factor 6 serum specific for serotype A and homologous mannan, and found that the mannohexaose was the most effective inhibitor. These, and results obtained by proton magnetic resonance (PMR) spectroscopy, methylation analysis, and other structural studies, suggest that the main component of this hexaose consists of one terminal alpha (1-3) linkage in addition to four alpha (1-2) linkages, and that this alpha (1-3)-containing mannohexaose may be responsible for the specificity of antigenic factor 6. Further results obtained by analyses of polarimetry, PMR spectroscopy, and chromium trioxide oxidation-methylation of C. albicans M-1012 mannan has a beta-linkage in addition to alpha-linkages, and that the mode of the beta-linkage is mainly (1-6) linkage. Further evidence obtained by Smith degradation-methylation analysis and by quantitative precipitin reactions of intact and acid-degraded mannan suggests that the antigenic determinant of antigenic factor 6 may be bound, via the beta (1-6) linkage, to C-6 of mannose residues involved in oligosaccharide side chains of serotype A mannan.","Immunochemical characterization of Candida albicans cell wall antigens: specific determinant of Candida albicans serotype A mannan Abs: We investigated the chemical structure of the specific determinant in the mannan of Candida albicans M-1012 (serotype A) strain. Acetolysis of the mannan, obtained by alkali extraction and purified as the copper complex, gave mannose and six oligosaccharides (from di- to hexasaccharide) and a small amount of a heptasaccharide. We examined the inhibition by these oligosaccharides up to hexaose of the precipitin reaction between anti-factor 6 serum specific for serotype A and homologous mannan, and found that the mannohexaose was the most effective inhibitor. These, and results obtained by proton magnetic resonance (PMR) spectroscopy, methylation analysis, and other structural studies, suggest that the main component of this hexaose consists of one terminal alpha (1-3) linkage in addition to four alpha (1-2) linkages, and that this alpha (1-3)-containing mannohexaose may be responsible for the specificity of antigenic factor 6. Further results obtained by analyses of polarimetry, PMR spectroscopy, and chromium trioxide oxidation-methylation of C. albicans M-1012 mannan has a beta-linkage in addition to alpha-linkages, and that the mode of the beta-linkage is mainly (1-6) linkage. Further evidence obtained by Smith degradation-methylation analysis and by quantitative precipitin reactions of intact and acid-degraded mannan suggests that the antigenic determinant of antigenic factor 6 may be bound, via the beta (1-6) linkage, to C-6 of mannose residues involved in oligosaccharide side chains of serotype A mannan."
1235018,Lindberg et al. 1982,Reactions of epidermal keratinocytes in sensitized and non-sensitized guinea pigs after dichromate exposure: an electron microscopic study,"The reaction in epidermal keratinocytes in sensitized and non-sensitized, normal guinea pigs after dichromate exposure has been investigated by electron microscopy. The results of the investigation show that the morphological alterations in keratinocytes in irritant and contact allergic reactions to dichromate are of a nonspecific nature. This underlines the fact that morphological reactions in the keratinocyte are uniform. The reactions were dose- and time-dependent. The morphology of the contact allergic reaction to dichromate in the guinea pig is consistent with that described for DNCB.","Reactions of epidermal keratinocytes in sensitized and non-sensitized guinea pigs after dichromate exposure: an electron microscopic study Abs: The reaction in epidermal keratinocytes in sensitized and non-sensitized, normal guinea pigs after dichromate exposure has been investigated by electron microscopy. The results of the investigation show that the morphological alterations in keratinocytes in irritant and contact allergic reactions to dichromate are of a nonspecific nature. This underlines the fact that morphological reactions in the keratinocyte are uniform. The reactions were dose- and time-dependent. The morphology of the contact allergic reaction to dichromate in the guinea pig is consistent with that described for DNCB."
1235016,Nordlind 1982,Effect of metal allergens on the DNA synthesis of unsensitized guinea pig lymphoid cells cultured in vitro,"The metal allergens cobalt chloride, mercuric chloride, nickel sulfate and potassium dichromate were tested regarding their effect on the DNA synthesis of lymphoid cells from unsensitized guinea pigs. At certain concentrations in the range of 10(-8) to 10(-6) M, all tested metal compounds stimulated the DNA synthesis of both thymocytes and peripheral lymphocytes after 48 h of culture. The most consistent stimulation with all tested metal allergens was obtained with spleen cells. Thymocytes and spleen cells were stimulated even when the small fraction of adherent cells was eliminated. Mercuric chloride and potassium dichromate were found to be inhibiting at 10(-6) to 10(-4) M, while cobalt chloride and nickel sulfate were less toxic and inhibiting at 10(-4) to 10(-3) M. At 5 h of culture the lowest inhibitory concentration of potassium dichromate was found to be about 100-fold lower than that of nickel sulfate, which may be of practical interest for the choice of concentrations used in human patch test. The lowest concentrations of mercuric chloride and potassium dichromate which at 5 h were inhibitory, were stimulating at 48 h. The presence of serum seemed to have a protective and modifying role regarding the effect of the various metal compounds on the DNA synthesis.","Effect of metal allergens on the DNA synthesis of unsensitized guinea pig lymphoid cells cultured in vitro Abs: The metal allergens cobalt chloride, mercuric chloride, nickel sulfate and potassium dichromate were tested regarding their effect on the DNA synthesis of lymphoid cells from unsensitized guinea pigs. At certain concentrations in the range of 10(-8) to 10(-6) M, all tested metal compounds stimulated the DNA synthesis of both thymocytes and peripheral lymphocytes after 48 h of culture. The most consistent stimulation with all tested metal allergens was obtained with spleen cells. Thymocytes and spleen cells were stimulated even when the small fraction of adherent cells was eliminated. Mercuric chloride and potassium dichromate were found to be inhibiting at 10(-6) to 10(-4) M, while cobalt chloride and nickel sulfate were less toxic and inhibiting at 10(-4) to 10(-3) M. At 5 h of culture the lowest inhibitory concentration of potassium dichromate was found to be about 100-fold lower than that of nickel sulfate, which may be of practical interest for the choice of concentrations used in human patch test. The lowest concentrations of mercuric chloride and potassium dichromate which at 5 h were inhibitory, were stimulating at 48 h. The presence of serum seemed to have a protective and modifying role regarding the effect of the various metal compounds on the DNA synthesis."
1235013,Jakobsen et al. 1982,Effects of potassium dichromate on the cell cycle of an established human cell line (NHIK 3025),"The effect of K2Cr2O7 exposure on the cell cycle phases of the human cell line NHIK 3025 has been studied. Inhibition of cell proliferation was found to depend on the concentration and length of exposure. An effect on cell proliferation was observed 6-9 h after addition of K2Cr2O7, whereas cell death was not observed until 3-4 days later. The cells were most sensitive in G2 phase. After exposure to 8 mumol/l K2Cr2O7 the greatest prolongation of the cell cycle was in G2 + M phase, but an increase of S phase was also observed. No prolongation of G1 phase could be measured. Our results thus indicate that K2Cr2O7 delays progression through the cell cycle.","Effects of potassium dichromate on the cell cycle of an established human cell line (NHIK 3025) Abs: The effect of K2Cr2O7 exposure on the cell cycle phases of the human cell line NHIK 3025 has been studied. Inhibition of cell proliferation was found to depend on the concentration and length of exposure. An effect on cell proliferation was observed 6-9 h after addition of K2Cr2O7, whereas cell death was not observed until 3-4 days later. The cells were most sensitive in G2 phase. After exposure to 8 mumol/l K2Cr2O7 the greatest prolongation of the cell cycle was in G2 + M phase, but an increase of S phase was also observed. No prolongation of G1 phase could be measured. Our results thus indicate that K2Cr2O7 delays progression through the cell cycle."
1235011,Rivolta et al. 1982,[Case study of lung cancer due to chromates diagnosed through cytologic examination of the sputum without x-rays evidence (author's transl)],"Epidermoid tumoral cells were found in the sputum of a 54 year old male who had workerd for 20 years in a varnish and enamel factory and was exposed to coloured pigments containing zinc and lead chromates. No radiologically or endoscopically visible lesions were found. The patient underwent ablation of the right inferior lobe in which the tumoral cells were localised. 14 months after surgery, repeated x-rays and sputum control were negative. This case exemplifies early diagnosis of occupational lung cancer using cytologic examination of the sputum.","[Case study of lung cancer due to chromates diagnosed through cytologic examination of the sputum without x-rays evidence (author's transl)] Abs: Epidermoid tumoral cells were found in the sputum of a 54 year old male who had workerd for 20 years in a varnish and enamel factory and was exposed to coloured pigments containing zinc and lead chromates. No radiologically or endoscopically visible lesions were found. The patient underwent ablation of the right inferior lobe in which the tumoral cells were localised. 14 months after surgery, repeated x-rays and sputum control were negative. This case exemplifies early diagnosis of occupational lung cancer using cytologic examination of the sputum."
1235010,Abraham et al. 1982,The effect of chromium on cholesterol-induced atherosclerosis in rabbits,"Rabbits fed on a 1% cholesterol diet for 30 days were injected daily with potassium chromate for a further 60 days. A 50% reduction in aortic intimal plaque area and in aortic total cholesterol content was observed. Control rabbits treated with chromium showed a significant increase in the chromium concentration of their aortas, liver and kidneys but not of the myocardium. Cholesterol-fed rabbits treated with chromium showed a significant increase in chromium concentrations in the liver and kidneys only. Serum cholesterol levels were consistently lower in the chromium-treated animals, although the differences did not reach significant levels.","The effect of chromium on cholesterol-induced atherosclerosis in rabbits Abs: Rabbits fed on a 1% cholesterol diet for 30 days were injected daily with potassium chromate for a further 60 days. A 50% reduction in aortic intimal plaque area and in aortic total cholesterol content was observed. Control rabbits treated with chromium showed a significant increase in the chromium concentration of their aortas, liver and kidneys but not of the myocardium. Cholesterol-fed rabbits treated with chromium showed a significant increase in chromium concentrations in the liver and kidneys only. Serum cholesterol levels were consistently lower in the chromium-treated animals, although the differences did not reach significant levels."
1235008,Paschin et al. 1982,Induction of dominant lethal mutations in male mice by potassium dichromate,,Induction of dominant lethal mutations in male mice by potassium dichromate Abs: 
1235007,Abraham et al. 1982,The action of chromium on serum lipids and on atherosclerosis in cholesterol-fed rabbits,"Eight rabbits, fed on a 1% cholesterol diet for 30 days, were injected daily with potassium chromate for a further 60 days. A 50% reduction in aortic intimal plaque area and in aortic total cholesterol content was observed. However, although levels of serum cholesterol and triglycerides were consistently lower and levels of high density lipoprotein fractions consistently higher in the chromium-treated as compared to the control rabbits, these differences did not reach statistical significance. A further 6 rabbits were injected with potassium chromate and fed on a 1% cholesterol diet for 12 weeks. Mean aortic cholesterol content (+/-SEM) was 40.23 mg/10 cm aortic length (+/-7.50) as compared to 66.24 mg/10 cm (+/- 7.89) in a control group (P less than 0.05), whereas the area of aortic intima covered by macroscopic plaques was 67.5% (+/-2.79) and 81.1% (+/-3.14) (P less than 0.01) respectively.","The action of chromium on serum lipids and on atherosclerosis in cholesterol-fed rabbits Abs: Eight rabbits, fed on a 1% cholesterol diet for 30 days, were injected daily with potassium chromate for a further 60 days. A 50% reduction in aortic intimal plaque area and in aortic total cholesterol content was observed. However, although levels of serum cholesterol and triglycerides were consistently lower and levels of high density lipoprotein fractions consistently higher in the chromium-treated as compared to the control rabbits, these differences did not reach statistical significance. A further 6 rabbits were injected with potassium chromate and fed on a 1% cholesterol diet for 12 weeks. Mean aortic cholesterol content (+/-SEM) was 40.23 mg/10 cm aortic length (+/-7.50) as compared to 66.24 mg/10 cm (+/- 7.89) in a control group (P less than 0.05), whereas the area of aortic intima covered by macroscopic plaques was 67.5% (+/-2.79) and 81.1% (+/-3.14) (P less than 0.01) respectively."
1235006,Mckenna and  Charleston 1982,Activation and excystation of Isospora felis and Isospora rivolta sporozoites,"Studies on the activation and excystation of I. felis and I. rivolta sporozoites revealed that, although some differences were apparent between the two, both were capable of activation under a wide range of conditions. Activation of both species took place in trypsin and bile between 21 and 43 C (the range tested) occurring rapidly at 39 C. Although the presence of bile appeared to be essential for this process that of trypsin did not. Neither the concentration of bile (above 5%), the type of bile, nor the hydrogen ion concentration had a marked effect on the level of activation. Pretreatment of oocysts in aqueous cysteine hydrochloride under CO2 or with sodium hypochlorite before exposure to trypsin and bile was not an essential prerequisite for the activation of I. felis and I. rivolta. However, higher levels of activation were attained when pretreatment was used. But for I. rivolta, the level of activation appeared to be less dependent on pretreatment for oocysts stored in sulfuric acid than for those stored in potassium dichromate. The process of activation and excystation of both species was essentially similar to that described for other species of disporocystic coccidia with heteroxenous life cycles. Sporozoites escaped following the collapse of the sporocyst wall and completed excystation through indentations and fractures at one or both ends of the oocyst.","Activation and excystation of Isospora felis and Isospora rivolta sporozoites Abs: Studies on the activation and excystation of I. felis and I. rivolta sporozoites revealed that, although some differences were apparent between the two, both were capable of activation under a wide range of conditions. Activation of both species took place in trypsin and bile between 21 and 43 C (the range tested) occurring rapidly at 39 C. Although the presence of bile appeared to be essential for this process that of trypsin did not. Neither the concentration of bile (above 5%), the type of bile, nor the hydrogen ion concentration had a marked effect on the level of activation. Pretreatment of oocysts in aqueous cysteine hydrochloride under CO2 or with sodium hypochlorite before exposure to trypsin and bile was not an essential prerequisite for the activation of I. felis and I. rivolta. However, higher levels of activation were attained when pretreatment was used. But for I. rivolta, the level of activation appeared to be less dependent on pretreatment for oocysts stored in sulfuric acid than for those stored in potassium dichromate. The process of activation and excystation of both species was essentially similar to that described for other species of disporocystic coccidia with heteroxenous life cycles. Sporozoites escaped following the collapse of the sporocyst wall and completed excystation through indentations and fractures at one or both ends of the oocyst."
1235004,Yoshimori and  Kamijoh 1982,Annotation: Drying conditions for potassium dichromate,"The optimum conditions for drying primary-standard or SRM grade potassium dichromate have been further examined, and it has been established that if organic impurities are present in the material the drying temperature should not exceed 200. At higher temperatures the organic matter is decomposed oxidatively by the dichromate, with a resultant error when the dichromate is used for standardization purposes.","Annotation: Drying conditions for potassium dichromate Abs: The optimum conditions for drying primary-standard or SRM grade potassium dichromate have been further examined, and it has been established that if organic impurities are present in the material the drying temperature should not exceed 200. At higher temperatures the organic matter is decomposed oxidatively by the dichromate, with a resultant error when the dichromate is used for standardization purposes."
1235003,Banoub and  Michon 1982,"Chromium trioxide oxidation of acetylated 3-amino-3,6-dideoxy-L-hexosides","Glycosides of the fully acetylated 3-amino-3,6-dideoxy-L-hexosides in the gluco, galacto, manno, and talo configurations have been treated with chromium trioxide in acetic acid. The alpha-L-methyl glycosides, which exist in the more stable chair conformation 1C4, with an axially oriented aglycon, are resistant to this oxidation, whereas the beta-L-linked glycoside having the gluco configuration (1C4 conformation) and the alpha-L-methyl glycoside having the talo configuration (4C1 conformation), both with equatorially oriented aglycons, are oxidized to the corresponding 5-adulosonates.","Chromium trioxide oxidation of acetylated 3-amino-3,6-dideoxy-L-hexosides Abs: Glycosides of the fully acetylated 3-amino-3,6-dideoxy-L-hexosides in the gluco, galacto, manno, and talo configurations have been treated with chromium trioxide in acetic acid. The alpha-L-methyl glycosides, which exist in the more stable chair conformation 1C4, with an axially oriented aglycon, are resistant to this oxidation, whereas the beta-L-linked glycoside having the gluco configuration (1C4 conformation) and the alpha-L-methyl glycoside having the talo configuration (4C1 conformation), both with equatorially oriented aglycons, are oxidized to the corresponding 5-adulosonates."
1235002,Kluwe 1982,Developed resistance to mercuric chloride nephrotoxicity: failure to protect against other nephrotoxicants,"Daily, oral treatment of rats for 14 days with 5 mg/kg of mercuric chloride (HgCl2) caused hypertrophy of the kidney, but no change in percent tissue water, or serum urea nitrogen (BUN) or creatinine concentrations. Upon histological examination, hypercellularity and increased basophilia of the outer medulla were observed. A single, subcutaneous injection of 20 mg/kg of potassium chromate (K2CrO4) increased kidney size and water content, as well as BUN and serum creatinine concentrations, and produced coagulative necrosis of the proximal convoluted tubules. Intraperitoneal injection of 125 mg/kg of hexachloro-1,3-butadiene (HCBD) increased kidney weight, percent water, BUN and serum creatinine, and produced necrosis of the proximal straight tubules in approximately half of the animals. 1 g/kg biphenyl, orally, produced only diffuse tubular swelling. Rats treated with 20 mg/kg K2CrO4, 125 mg/kg HCBD or 1 g/kg biphenyl following 14 days of treatment with 5 mg/kg HgCl2 generally displayed the symptoms of both types of treatment, and the severity of the K2CrO4, HCBD and biphenyl effects were substantially the same as in those without HgCl2 pretreatment. Developed resistance to HgCl2 nephrotoxicity, therefore, appears to have little effect on response of the kidney to other nephrotoxicants.","Developed resistance to mercuric chloride nephrotoxicity: failure to protect against other nephrotoxicants Abs: Daily, oral treatment of rats for 14 days with 5 mg/kg of mercuric chloride (HgCl2) caused hypertrophy of the kidney, but no change in percent tissue water, or serum urea nitrogen (BUN) or creatinine concentrations. Upon histological examination, hypercellularity and increased basophilia of the outer medulla were observed. A single, subcutaneous injection of 20 mg/kg of potassium chromate (K2CrO4) increased kidney size and water content, as well as BUN and serum creatinine concentrations, and produced coagulative necrosis of the proximal convoluted tubules. Intraperitoneal injection of 125 mg/kg of hexachloro-1,3-butadiene (HCBD) increased kidney weight, percent water, BUN and serum creatinine, and produced necrosis of the proximal straight tubules in approximately half of the animals. 1 g/kg biphenyl, orally, produced only diffuse tubular swelling. Rats treated with 20 mg/kg K2CrO4, 125 mg/kg HCBD or 1 g/kg biphenyl following 14 days of treatment with 5 mg/kg HgCl2 generally displayed the symptoms of both types of treatment, and the severity of the K2CrO4, HCBD and biphenyl effects were substantially the same as in those without HgCl2 pretreatment. Developed resistance to HgCl2 nephrotoxicity, therefore, appears to have little effect on response of the kidney to other nephrotoxicants."
1235000,Debetto et al. 1982,Effects of potassium dichromate on ATP content of mammalian cells cultured in vitro,"In order to elucidate the mechanism of the cytotoxic activity of hexavalent chromium (Cr(VI)), the alterations of intracellular ATP levels induced by potassium dichromate in cultured hamster fibroblasts (BHK line) have been studied. Two kinds of treatment procedures were adopted: (1) BHK cell suspensions were exposed to 0.05--1.00 mM K2Cr2O7 in Hanks' balanced salt solution (BSS) for up to 180 min and ATP concentrations were determined immediately after the exposure to Cr(VI). A decrease of ATP content was observed with 0.25--12.00 mM K2Cr2O7 but only in the case of the highest dose was it related in a linear fashion to the duration of the treatment. (2) Cells were preincubated in BSS for 30 min with 0.05--1.00 mM dichromate. They were then reincubated in Eagle's minimal essential medium (MEM) for up to 180 min and ATP was measured at different time points. Immediately after the exposure to chromium all the treated cultures showed a depletion of ATP content. However while the cells treated with 0.25--0.25 mM dichromate rapidly resumed ATP levels very similar to that of the control, no recovery was detected in cells treated with 0.50 and 1.0 mM K2Cr2O7, even after 180 min. The observed effects have been attributed to the oxidizing activity of Cr(VI), which subtracts electrons from electron donors involved in metabolic pathways producing ATP, and to the ability of Cr(III), deriving from Cr(VI) reduction, to form stable coordination complexes with ATP precursors and enzymes involved in ATP synthesis.","Effects of potassium dichromate on ATP content of mammalian cells cultured in vitro Abs: In order to elucidate the mechanism of the cytotoxic activity of hexavalent chromium (Cr(VI)), the alterations of intracellular ATP levels induced by potassium dichromate in cultured hamster fibroblasts (BHK line) have been studied. Two kinds of treatment procedures were adopted: (1) BHK cell suspensions were exposed to 0.05--1.00 mM K2Cr2O7 in Hanks' balanced salt solution (BSS) for up to 180 min and ATP concentrations were determined immediately after the exposure to Cr(VI). A decrease of ATP content was observed with 0.25--12.00 mM K2Cr2O7 but only in the case of the highest dose was it related in a linear fashion to the duration of the treatment. (2) Cells were preincubated in BSS for 30 min with 0.05--1.00 mM dichromate. They were then reincubated in Eagle's minimal essential medium (MEM) for up to 180 min and ATP was measured at different time points. Immediately after the exposure to chromium all the treated cultures showed a depletion of ATP content. However while the cells treated with 0.25--0.25 mM dichromate rapidly resumed ATP levels very similar to that of the control, no recovery was detected in cells treated with 0.50 and 1.0 mM K2Cr2O7, even after 180 min. The observed effects have been attributed to the oxidizing activity of Cr(VI), which subtracts electrons from electron donors involved in metabolic pathways producing ATP, and to the ability of Cr(III), deriving from Cr(VI) reduction, to form stable coordination complexes with ATP precursors and enzymes involved in ATP synthesis."
1234997,Kramp and  Lorentz 1982,Glucose transport in chronically altered rat nephrons,"Microinjection experiments were performed in anesthetized rats to study the tubular absorptive capacity for glucose (TG) in normal and chronically altered tubules, i.e., tubules that sustained anatomical repair and compensatory changes of their previously normal configuration after acute damage. TG was complete when the glucose load injected in normal or altered early or late proximal convolutions was less than or equal to 1.5 or less than or equal to 10 pmol . s-1, respectively. In normal tubules, TmG was 10 and 5 pmol . s-1 after early and late proximal microinjections, respectively. After early proximal microinjections in altered tubules, different levels of TmG were found. They related to the degree of compensatory growth. TmG was approximately 12, 24, or 35 pmol . s-1, respectively, in altered tubules with minor, moderate, or major compensatory growth. After late proximal microinjections, TmG was 15 pmol . s-1. TG variability was greater in altered than in normal tubules. Correlation between structural and functional compensatory changes was thus demonstrated. Furthermore, an important, albeit latent, absorptive capacity for glucose of the proximal straight tubule was found.","Glucose transport in chronically altered rat nephrons Abs: Microinjection experiments were performed in anesthetized rats to study the tubular absorptive capacity for glucose (TG) in normal and chronically altered tubules, i.e., tubules that sustained anatomical repair and compensatory changes of their previously normal configuration after acute damage. TG was complete when the glucose load injected in normal or altered early or late proximal convolutions was less than or equal to 1.5 or less than or equal to 10 pmol . s-1, respectively. In normal tubules, TmG was 10 and 5 pmol . s-1 after early and late proximal microinjections, respectively. After early proximal microinjections in altered tubules, different levels of TmG were found. They related to the degree of compensatory growth. TmG was approximately 12, 24, or 35 pmol . s-1, respectively, in altered tubules with minor, moderate, or major compensatory growth. After late proximal microinjections, TmG was 15 pmol . s-1. TG variability was greater in altered than in normal tubules. Correlation between structural and functional compensatory changes was thus demonstrated. Furthermore, an important, albeit latent, absorptive capacity for glucose of the proximal straight tubule was found."
1234995,Rainaldi et al. 1982,"Thioguanine resistance, ouabain resistance and sister chromatid exchanges in V79/AP4 Chinese hamster cells treated with potassium dichromate","The biological activity of potassium dichromate (K2Cr2O7) was assayed in V79/AP4 Chinese hamster cells by measuring two mutational end points, thioguanine (TG) resistance and ouabain (OUA) resistance, and two non-mutational end points, cytotoxicity and sister chromatid exchanges (SCE). By exposing the cells for 1 h to the chemical, all biological end points examined were affected by the treatment in a dose-dependent manner. Moreover the combined use of the two selective systems indicated that chromium induces base-pair substitutions in mammalian cells in culture.","Thioguanine resistance, ouabain resistance and sister chromatid exchanges in V79/AP4 Chinese hamster cells treated with potassium dichromate Abs: The biological activity of potassium dichromate (K2Cr2O7) was assayed in V79/AP4 Chinese hamster cells by measuring two mutational end points, thioguanine (TG) resistance and ouabain (OUA) resistance, and two non-mutational end points, cytotoxicity and sister chromatid exchanges (SCE). By exposing the cells for 1 h to the chemical, all biological end points examined were affected by the treatment in a dose-dependent manner. Moreover the combined use of the two selective systems indicated that chromium induces base-pair substitutions in mammalian cells in culture."
1234994,Elliott et al. 1982,Gentamicin nephrotoxicity. II. Definition of conditions necessary to induce acquired insensitivity,"Acquired insensitivity to the nephrotoxic effects of gentamicin develops in Fischer 344 rats after 10 to 14 days' treatment after development of histologic acute tubular necrosis in a setting of extensive histologic regeneration. To determine the relative importance of aminoglycoside exposure, necrosis, and regeneration in the induction of insensitivity, we examined the effect on gentamicin toxicity of prior non-aminoglycoside-mediated tubular necrosis, antecedent nonnecrotizing aminoglycoside exposure, and unilateral Nx-induced renal tubular hyperplasia. Pretreatment with potassium dichromate, which causes tubular necrosis in the same part of the renal cortex as gentamicin, reduced gentamicin-mediated elevation of Scr but had little effect on gentamicin-related tubular dysfunction or structural damage. Pretreatment with netilmicin, which does not cause tubular necrosis, increased the sensitivity of the kidney to gentamicin; toxicity occurred earlier and was more severe. Antecedent unilateral Nx had no demonstrable effect on susceptibility to gentamicin-associated dysfunction, but histologic renal tubular epithelial regeneration and recovery from dysfunction occurred earlier, These results suggest that necrosis and/or regeneration is the major prerequisite for development of gentamicin insensitivity and that the onset of insensitivity is temporally related to the appearance of necrosis and regeneration. However, non-aminoglycoside-mediated necrosis and regeneration fail to fully-re-create insensitivity, suggesting that exposure to gentamicin is also necessary.","Gentamicin nephrotoxicity. II. Definition of conditions necessary to induce acquired insensitivity Abs: Acquired insensitivity to the nephrotoxic effects of gentamicin develops in Fischer 344 rats after 10 to 14 days' treatment after development of histologic acute tubular necrosis in a setting of extensive histologic regeneration. To determine the relative importance of aminoglycoside exposure, necrosis, and regeneration in the induction of insensitivity, we examined the effect on gentamicin toxicity of prior non-aminoglycoside-mediated tubular necrosis, antecedent nonnecrotizing aminoglycoside exposure, and unilateral Nx-induced renal tubular hyperplasia. Pretreatment with potassium dichromate, which causes tubular necrosis in the same part of the renal cortex as gentamicin, reduced gentamicin-mediated elevation of Scr but had little effect on gentamicin-related tubular dysfunction or structural damage. Pretreatment with netilmicin, which does not cause tubular necrosis, increased the sensitivity of the kidney to gentamicin; toxicity occurred earlier and was more severe. Antecedent unilateral Nx had no demonstrable effect on susceptibility to gentamicin-associated dysfunction, but histologic renal tubular epithelial regeneration and recovery from dysfunction occurred earlier, These results suggest that necrosis and/or regeneration is the major prerequisite for development of gentamicin insensitivity and that the onset of insensitivity is temporally related to the appearance of necrosis and regeneration. However, non-aminoglycoside-mediated necrosis and regeneration fail to fully-re-create insensitivity, suggesting that exposure to gentamicin is also necessary."
1234993,Lindsay et al. 1982,"Sporogony of Isospora suis Biester, 1934 of swine","Sporogony of Isospora suis of swine is described. Unsporulated oocysts were collected immediately after defecation, mixed in 2.5% potassium dichromate solution, incubated at various temperatures, examined at different time intervals, and classified as to stage of development. The uninucleate sporont underwent nuclear division and became binucleated, and then divided to form two round, uninucleate sporoblasts. Binucleate sporoblasts elongated to form binucleate sporocysts, each of which then gave rise to four sporozoites. Sporulation was completed within 56 hr at 20 C, 40 hr at 25 C, 16 hr at 30 C, and 12 hr at 37 C. No sporulation occurred at 4, 40, 42, 45, or 50 C. The thermal death point was between 37 and 40 C.","Sporogony of Isospora suis Biester, 1934 of swine Abs: Sporogony of Isospora suis of swine is described. Unsporulated oocysts were collected immediately after defecation, mixed in 2.5% potassium dichromate solution, incubated at various temperatures, examined at different time intervals, and classified as to stage of development. The uninucleate sporont underwent nuclear division and became binucleated, and then divided to form two round, uninucleate sporoblasts. Binucleate sporoblasts elongated to form binucleate sporocysts, each of which then gave rise to four sporozoites. Sporulation was completed within 56 hr at 20 C, 40 hr at 25 C, 16 hr at 30 C, and 12 hr at 37 C. No sporulation occurred at 4, 40, 42, 45, or 50 C. The thermal death point was between 37 and 40 C."
1234990,Moon et al. 1982,"Experimental fecal transmission of human cryptosporidia to pigs, and attempted treatment with an ornithine decarboxylase inhibitor","Fecal material collected from an immunologically deficient man with persistent cryptosporidia infection was stored in potassium dichromate for two weeks and then fed (inoculated) to newborn pigs. The six inoculated newborn pigs shed the organism in their feces starting four to five days afer inoculation and continuing for as long as 22 days after inoculation. Pigs which were killed and necropsied while shedding had cryptosporidia infection of ileum, cecum, and colon. Infected pigs had atrophied ileal villi and flattened irregular cecal and colonic epithelium. Uninoculated littermate controls remained free to the infection and had histologically normal intestinal tracts at necropsy. Treatment of three of the six inoculated pigs with the ornithine decarboxylase inhibitor, DL-alpha-difluoromethylornithine, orally for ten days had no apparent effect on the infection.","Experimental fecal transmission of human cryptosporidia to pigs, and attempted treatment with an ornithine decarboxylase inhibitor Abs: Fecal material collected from an immunologically deficient man with persistent cryptosporidia infection was stored in potassium dichromate for two weeks and then fed (inoculated) to newborn pigs. The six inoculated newborn pigs shed the organism in their feces starting four to five days afer inoculation and continuing for as long as 22 days after inoculation. Pigs which were killed and necropsied while shedding had cryptosporidia infection of ileum, cecum, and colon. Infected pigs had atrophied ileal villi and flattened irregular cecal and colonic epithelium. Uninoculated littermate controls remained free to the infection and had histologically normal intestinal tracts at necropsy. Treatment of three of the six inoculated pigs with the ornithine decarboxylase inhibitor, DL-alpha-difluoromethylornithine, orally for ten days had no apparent effect on the infection."
1234986,Nordlind and  Thyberg 1983,Effect of metal allergens on thymocytes from unsensitized guinea pigs: a comparative light and electron microscopic study,"In the present investigation we studied the effects of different metal allergens on cell counts, dye exclusion, and fine structure of unsensitized guinea pig thymocytes cultured in vitro for up to 96 H. At concentrations which inhibit DNA synthesis of lymphoid cells, the metal salts most often caused cell degeneration as judged by dye exclusion test and electron microscopy. DNA synthesis stimulating concentrations of mercuric chloride gave an increase in the percentage of viable cells. Absolute cell counts were not changed with either DNA synthesis inhibiting or stimulating concentrations. The importance of using different methods in investigating effects of metal allergens on lymphocytes in vitro is pointed out.","Effect of metal allergens on thymocytes from unsensitized guinea pigs: a comparative light and electron microscopic study Abs: In the present investigation we studied the effects of different metal allergens on cell counts, dye exclusion, and fine structure of unsensitized guinea pig thymocytes cultured in vitro for up to 96 H. At concentrations which inhibit DNA synthesis of lymphoid cells, the metal salts most often caused cell degeneration as judged by dye exclusion test and electron microscopy. DNA synthesis stimulating concentrations of mercuric chloride gave an increase in the percentage of viable cells. Absolute cell counts were not changed with either DNA synthesis inhibiting or stimulating concentrations. The importance of using different methods in investigating effects of metal allergens on lymphocytes in vitro is pointed out."
1234985,Nordlind 1983,Inhibition of lymphoid cell DNA synthesis by metal allergens at various concentrations. Effect on short-time cultured nonadherent cells compared to nonseparated cells,"Metal allergen concentrations inhibiting lymphoid cell DNA synthesis were tested on short-time cultured nonadherent and nonseparated thymic and splenic cells. With all tested metal allergens, the DNA-synthesis-inhibiting effect was more marked for nonadherent compared to nonseparated splenic cells. In thymocytes, a stronger inhibition of nonadherent cells was seen after addition of mercuric chloride. A protective or modifying role of adherent cells towards inhibiting or toxic effects of metal allergens in vitro is postulated.","Inhibition of lymphoid cell DNA synthesis by metal allergens at various concentrations. Effect on short-time cultured nonadherent cells compared to nonseparated cells Abs: Metal allergen concentrations inhibiting lymphoid cell DNA synthesis were tested on short-time cultured nonadherent and nonseparated thymic and splenic cells. With all tested metal allergens, the DNA-synthesis-inhibiting effect was more marked for nonadherent compared to nonseparated splenic cells. In thymocytes, a stronger inhibition of nonadherent cells was seen after addition of mercuric chloride. A protective or modifying role of adherent cells towards inhibiting or toxic effects of metal allergens in vitro is postulated."
1234984,Stevenson and  Morgan 1983,Investigation and prevention of chromate dermatitis in colour television manufacture,"Cases of chromate (11104599) dermatitis among color television manufacture workers were described. Twenty cases of occupational dermatitis occurred among employees in a flow coat mill that manufactured color television tubes. The dermatitis took the form of a rash that appeared on the hands and feet of workers who applied a solution of ammonium-dichromate (7789095) (ADC) in polyvinyl-alcohol (9002862) (PVA) to a phosphor material on the screen of a color television. The hands of the workers were examined under a lamp on a Monday morning after being away from work for 2 days. Patch tests using samples of PVA, the phosphor material, or potassium-dichromate (7778509) (PDC) were applied. Fourteen of the cases had a positive response to PDC patch tests. All responses to the PVA and phosphor patch tests were negative. Lamp examination showed fluorescence around the finger nails and in the creases of fingers. The authors conclude that exposure to ADC was responsible for the dermatitis. Exposure to ADC and other chemicals has been reduced and since that time no new cases have been reported.","Investigation and prevention of chromate dermatitis in colour television manufacture Abs: Cases of chromate (11104599) dermatitis among color television manufacture workers were described. Twenty cases of occupational dermatitis occurred among employees in a flow coat mill that manufactured color television tubes. The dermatitis took the form of a rash that appeared on the hands and feet of workers who applied a solution of ammonium-dichromate (7789095) (ADC) in polyvinyl-alcohol (9002862) (PVA) to a phosphor material on the screen of a color television. The hands of the workers were examined under a lamp on a Monday morning after being away from work for 2 days. Patch tests using samples of PVA, the phosphor material, or potassium-dichromate (7778509) (PDC) were applied. Fourteen of the cases had a positive response to PDC patch tests. All responses to the PVA and phosphor patch tests were negative. Lamp examination showed fluorescence around the finger nails and in the creases of fingers. The authors conclude that exposure to ADC was responsible for the dermatitis. Exposure to ADC and other chemicals has been reduced and since that time no new cases have been reported."
1234982,Venitt and  Bosworth 1983,The development of anaerobic methods for bacterial mutation assays: aerobic and anaerobic fluctuation tests of human faecal extracts and reference mutagens,"Methods for performing microtitre fluctuation tests in an anaerobic enclosure have been devised in order to study the mutagenic activity of human faecal extracts under conditions of strict anaerobiosis. Under these conditions (monitored by growth of obligate anaerobes), two mutagens (4-chloromethylbiphenyl (4CMB) and potassium dichromate) were reproducibly mutagenic to Salmonella typhimurium TA 100 and Escherichia coli WP2uvrA(pKM101), respectively. We investigated the mutagenicity of aqueous extracts of faeces, prepared aerobically and anaerobically, collected from a single donor. Bioassay of 5 faecal extracts showed that 4 contained substances which promoted auxotrophic growth of his- and tryp- bacteria, and were therefore unsuitable for mutagenicity assay. The remaining extract (half of which was prepared aerobically, the other anaerobically) was assayed for mutagenicity in S. typhimurium TA 100. Reproducible dose-response curves were obtained with the aerobic extract and with the anaerobic extract when both were assayed under aerobic conditions. Negative results were obtained when the anaerobic or aerobic extracts were assayed anaerobically, under conditions where concurrent assays of 4CMB were positive. We conclude that bacterial fluctuation tests using reversion from auxotrophy to prototrophy as the genetic marker can be seriously compromised by the presence of substances (including amino acids) in the test material which promote auxotrophic growth. Moreover, it is clear that the results and interpretation of mutagenicity tests of faecal extracts are very dependent on whether air is present or absent during both extraction and assay.","The development of anaerobic methods for bacterial mutation assays: aerobic and anaerobic fluctuation tests of human faecal extracts and reference mutagens Abs: Methods for performing microtitre fluctuation tests in an anaerobic enclosure have been devised in order to study the mutagenic activity of human faecal extracts under conditions of strict anaerobiosis. Under these conditions (monitored by growth of obligate anaerobes), two mutagens (4-chloromethylbiphenyl (4CMB) and potassium dichromate) were reproducibly mutagenic to Salmonella typhimurium TA 100 and Escherichia coli WP2uvrA(pKM101), respectively. We investigated the mutagenicity of aqueous extracts of faeces, prepared aerobically and anaerobically, collected from a single donor. Bioassay of 5 faecal extracts showed that 4 contained substances which promoted auxotrophic growth of his- and tryp- bacteria, and were therefore unsuitable for mutagenicity assay. The remaining extract (half of which was prepared aerobically, the other anaerobically) was assayed for mutagenicity in S. typhimurium TA 100. Reproducible dose-response curves were obtained with the aerobic extract and with the anaerobic extract when both were assayed under aerobic conditions. Negative results were obtained when the anaerobic or aerobic extracts were assayed anaerobically, under conditions where concurrent assays of 4CMB were positive. We conclude that bacterial fluctuation tests using reversion from auxotrophy to prototrophy as the genetic marker can be seriously compromised by the presence of substances (including amino acids) in the test material which promote auxotrophic growth. Moreover, it is clear that the results and interpretation of mutagenicity tests of faecal extracts are very dependent on whether air is present or absent during both extraction and assay."
1234980,Kroon 1983,"Standard photopatch testing with Waxtar, para-aminobenzoic acid, potassium dichromate and balsam of Peru","194 patients were standard photopatch tested with Waxtar as is (coal tar 5%) and 161 patients were photopatch tested with para-aminobenzoic acid (PABA) 5% in alcohol, potassium dichromate 0.5% in petrolatum, and a mixture of balsams of Peru as is. The photopatches were irradiated with UVA. 40 patients (25%) had phototoxic reactions to Waxtar and 4 of them showed pigmentation after 7 days. Only a few patients had photocontact urticaria. 1 patient had a late-reaction to PABA and showed a cross-reaction to glyceryl PABA but a negative reaction to paraphenylenediamine (PPD) and benzocaine 5% in the standard test. No patients had positive photopatch reactions to potassium dichromate when irradiated with UVA. 2 patients had phototoxic reactions to balsam of Peru. None had photoallergic reactions. Standard photopatch testing is a time consuming procedure which creates problems both for the staff and for the patients. The yield of unexpected, relevant positive reactions is insignificant. From a cost-benefit view, photopatch testing is only warranted in cases giving rise to a clinical suspicion of photodermatitis.","Standard photopatch testing with Waxtar, para-aminobenzoic acid, potassium dichromate and balsam of Peru Abs: 194 patients were standard photopatch tested with Waxtar as is (coal tar 5%) and 161 patients were photopatch tested with para-aminobenzoic acid (PABA) 5% in alcohol, potassium dichromate 0.5% in petrolatum, and a mixture of balsams of Peru as is. The photopatches were irradiated with UVA. 40 patients (25%) had phototoxic reactions to Waxtar and 4 of them showed pigmentation after 7 days. Only a few patients had photocontact urticaria. 1 patient had a late-reaction to PABA and showed a cross-reaction to glyceryl PABA but a negative reaction to paraphenylenediamine (PPD) and benzocaine 5% in the standard test. No patients had positive photopatch reactions to potassium dichromate when irradiated with UVA. 2 patients had phototoxic reactions to balsam of Peru. None had photoallergic reactions. Standard photopatch testing is a time consuming procedure which creates problems both for the staff and for the patients. The yield of unexpected, relevant positive reactions is insignificant. From a cost-benefit view, photopatch testing is only warranted in cases giving rise to a clinical suspicion of photodermatitis."
1234978,Merritt et al. 1983,XPS analysis of 316 LVM corroded in serum and saline,"Surface chemical analysis by x-ray photoelectron spectroscopy (XPS) was undertaken on 316 LVM stainless steel in the attempt to better understand corrosion occurring in vivo. Samples were dipped in saline or in blood serum, corroded in serum or saline by the application of a 5 volt anodic potential, or corroded by fretting. The products produced by fretting corrosion were also examined. XPS analysis revealed rapid protein coating of the stainless steel surfaces exposed to serum, changes in the oxidation state of the surfaces, and changes in the chlorine on the surface. In addition it was demonstrated that the corrosion products generated by fretting in saline had an oxidation state similar to that of chronic chloride whereas the corrosion products generated in serum had an oxidation state similar to that of potassium dichromate. These findings may have important implications since the chromium in dichromate is more biologically active than that in chronic chloride.","XPS analysis of 316 LVM corroded in serum and saline Abs: Surface chemical analysis by x-ray photoelectron spectroscopy (XPS) was undertaken on 316 LVM stainless steel in the attempt to better understand corrosion occurring in vivo. Samples were dipped in saline or in blood serum, corroded in serum or saline by the application of a 5 volt anodic potential, or corroded by fretting. The products produced by fretting corrosion were also examined. XPS analysis revealed rapid protein coating of the stainless steel surfaces exposed to serum, changes in the oxidation state of the surfaces, and changes in the chlorine on the surface. In addition it was demonstrated that the corrosion products generated by fretting in saline had an oxidation state similar to that of chronic chloride whereas the corrosion products generated in serum had an oxidation state similar to that of potassium dichromate. These findings may have important implications since the chromium in dichromate is more biologically active than that in chronic chloride."
1234975,Lindberg et al. 1983,Elemental changes at irritant reactions due to chromate and nickel in guinea-pig epidermis,The present investigation was performed to examine the possibility of using energy dispersive X-ray microanalysis (EDX) to obtain information on epidermal reactions at irritant dermatitis. The elemental redistribution in the stratum germinativum and stratum spinosum of the guinea-pig epidermis after intradermal injection of a chromate and a nickel solution was studied in thick cryo-sections. The two solutions caused different changes in elemental content in both cell layers. Nickel sulfate caused a conspicuous decrease in K levels whereas Na and Cl were elevated in both cell layers. Potassium chromate caused an increase in Cl but lowered the P values. The result of this study show that it is possible to use EDX-analysis of thick skin sections to obtain information on physiologically relevant alterations in epidermis at irritant dermatitis.,Elemental changes at irritant reactions due to chromate and nickel in guinea-pig epidermis Abs: The present investigation was performed to examine the possibility of using energy dispersive X-ray microanalysis (EDX) to obtain information on epidermal reactions at irritant dermatitis. The elemental redistribution in the stratum germinativum and stratum spinosum of the guinea-pig epidermis after intradermal injection of a chromate and a nickel solution was studied in thick cryo-sections. The two solutions caused different changes in elemental content in both cell layers. Nickel sulfate caused a conspicuous decrease in K levels whereas Na and Cl were elevated in both cell layers. Potassium chromate caused an increase in Cl but lowered the P values. The result of this study show that it is possible to use EDX-analysis of thick skin sections to obtain information on physiologically relevant alterations in epidermis at irritant dermatitis.
1234974,Bilaspuri and  Guraya 1983,"Effects of different fixatives on the development of acrosomal system during spermiogenesis in buffalo, goat and ram","The effects of Zenker-formol, Carnoy, Orth and Bouin's fixatives on the development of acrosomal system during spermiogenesis in buffalo, goat and ram were compared. Using Zenker-formol, Orth and Bouin's fixatives it was found in the Golgi and cap phases that the acrosome is derived from the inner and outer zones of acrosomal system. With Carnoy's fixative it was seen that the weakly stained granules are surrounded by a vacuolar space. In the acrosome and maturation phases the acrosome and head cap stain uniformly in the tissue fixed in Zenker-formol, Orth and Bouin's fixatives. In Carnoy fixed tissue the PAS-positive material in the spermatids is weakly stained.","Effects of different fixatives on the development of acrosomal system during spermiogenesis in buffalo, goat and ram Abs: The effects of Zenker-formol, Carnoy, Orth and Bouin's fixatives on the development of acrosomal system during spermiogenesis in buffalo, goat and ram were compared. Using Zenker-formol, Orth and Bouin's fixatives it was found in the Golgi and cap phases that the acrosome is derived from the inner and outer zones of acrosomal system. With Carnoy's fixative it was seen that the weakly stained granules are surrounded by a vacuolar space. In the acrosome and maturation phases the acrosome and head cap stain uniformly in the tissue fixed in Zenker-formol, Orth and Bouin's fixatives. In Carnoy fixed tissue the PAS-positive material in the spermatids is weakly stained."
1234973,Turk and  Parker 1983,Chronic cell-mediated immune reactions to metals,"Cell mediated immune reactions may underly toxic reactions to certain metals, particularly Cr, Ni, Zr, Be, and Hg. Metal conjugated to a carrier protein forms the immunogen, but how the metal acts as a hapten is poorly understood. The possibility that the metal changes the antigenicity of the protein by changing its configuration is discussed and could explain cross reactions between Zr and Cr. Most reactions are contact sensitivity reaction, but granulomas may also develop to Be and Zr. These are epithelioid cell lesions associated with fibroblast proliferation and increased collagen synthesis. Sensitization of guinea pigs to Be and Hg is possible by epicutaneous contact. Cr, Ni, and Zr sensitivity need Freund's adjuvant and frequent intradermal injections. Three initial protocols have been compared and their efficacy for each metal assessed. Specific unresponsiveness for Cr and Ni can be induced by intratracheal installation prior to attempted sensitization. After sensitivity has developed, unresponsiveness to Cr can be induced by intravenous injection of the metal together with an epicutaneous application given within 24 hours. Flare up of old Cr reaction sites can also be induced by intravenous injection of the metal. The reaction lasts for 48 hours, is associated with increased vascular permeability and subepidermal infiltration with basophil leucocytes.","Chronic cell-mediated immune reactions to metals Abs: Cell mediated immune reactions may underly toxic reactions to certain metals, particularly Cr, Ni, Zr, Be, and Hg. Metal conjugated to a carrier protein forms the immunogen, but how the metal acts as a hapten is poorly understood. The possibility that the metal changes the antigenicity of the protein by changing its configuration is discussed and could explain cross reactions between Zr and Cr. Most reactions are contact sensitivity reaction, but granulomas may also develop to Be and Zr. These are epithelioid cell lesions associated with fibroblast proliferation and increased collagen synthesis. Sensitization of guinea pigs to Be and Hg is possible by epicutaneous contact. Cr, Ni, and Zr sensitivity need Freund's adjuvant and frequent intradermal injections. Three initial protocols have been compared and their efficacy for each metal assessed. Specific unresponsiveness for Cr and Ni can be induced by intratracheal installation prior to attempted sensitization. After sensitivity has developed, unresponsiveness to Cr can be induced by intravenous injection of the metal together with an epicutaneous application given within 24 hours. Flare up of old Cr reaction sites can also be induced by intravenous injection of the metal. The reaction lasts for 48 hours, is associated with increased vascular permeability and subepidermal infiltration with basophil leucocytes."
1234972,Iserson et al. 1983,Failure of dialysis therapy in potassium dichromate poisoning,"A fatal case of oral ingestion of potassium dichromate is presented. Following an initial presentation of abdominal pain and vomiting, the patient had a rapid progression to coma with the development of methemoglobinemia, coagulopathy, gastrointestinal hemorrhage, and respiratory distress syndrome. A blood concentration of chromium on admission was 5,800 mcg/dL, 80% of which was found to be in the intracellular fraction. Supportive treatment was also initiated as a four-hour period of hemodialysis followed by a one-hour period of charcoal hemoperfusion. Neither of these treatment modalities was found to significantly remove chromium from whole blood and neither seemed to affect the progression or outcome of this intoxication. We conclude that the ingestion of potassium dichromate is highly toxic and may rapidly lead to death. Hemodialysis and charcoal hemoperfusion appear to have little role in the management of chromium intoxication.","Failure of dialysis therapy in potassium dichromate poisoning Abs: A fatal case of oral ingestion of potassium dichromate is presented. Following an initial presentation of abdominal pain and vomiting, the patient had a rapid progression to coma with the development of methemoglobinemia, coagulopathy, gastrointestinal hemorrhage, and respiratory distress syndrome. A blood concentration of chromium on admission was 5,800 mcg/dL, 80% of which was found to be in the intracellular fraction. Supportive treatment was also initiated as a four-hour period of hemodialysis followed by a one-hour period of charcoal hemoperfusion. Neither of these treatment modalities was found to significantly remove chromium from whole blood and neither seemed to affect the progression or outcome of this intoxication. We conclude that the ingestion of potassium dichromate is highly toxic and may rapidly lead to death. Hemodialysis and charcoal hemoperfusion appear to have little role in the management of chromium intoxication."
1234970,Nordlind and  Sandberg 1983,Leukocytes from patients allergic to chromium and nickel examined by the sealed capillary migration technique,"Leukocytes from patients allergic to chromium and nickel were studied by a sealed capillary migration test. The migration indices were determined at 2, 5 and 24 h. The chromium-allergic group could be differentiated from the control group at all investigated times, and especially at 2 and 5 h, by using a potassium dichromate concentration of 1.7 x 10(-5) M in the capillaries. The migration indices in the nickel-allergic group could not be used for discrimination from the controls. The highest chromate (1.1 x 10(-4) M) and nickel sulfate (3.8 x 10(-4) M0 concentrations inhibited the migration of leukocytes from both patients and controls, indicating toxic effects.","Leukocytes from patients allergic to chromium and nickel examined by the sealed capillary migration technique Abs: Leukocytes from patients allergic to chromium and nickel were studied by a sealed capillary migration test. The migration indices were determined at 2, 5 and 24 h. The chromium-allergic group could be differentiated from the control group at all investigated times, and especially at 2 and 5 h, by using a potassium dichromate concentration of 1.7 x 10(-5) M in the capillaries. The migration indices in the nickel-allergic group could not be used for discrimination from the controls. The highest chromate (1.1 x 10(-4) M) and nickel sulfate (3.8 x 10(-4) M0 concentrations inhibited the migration of leukocytes from both patients and controls, indicating toxic effects."
1234969,Iijima et al. 1983,Developmental and cytogenetic effects of potassium dichromate on mouse embryos in vitro,"Mouse blastocysts and egg cylinders were treated in vitro with potassium dichromate (K2Cr2O7, 5 × 10?7 to 2 × 10?6 M), and the effects on postimplantation development and induction of sister chromatid exchanges (SCEs) were determined. When blastocysts were treated for six days with 1 × 10?6 M K2Cr2O7, the number of embryos with growing inner cell masses (ICMs) and ICMs that were differentiated into primary endoderm and ectoderm were significantly reduced. The number of embryos forming trophoblast outgrowths was not reduced, but outgrowth formed in the presence of 2 × 10?6 M K2Cr2O7 were small and began to degenerate by the end of the treatment. Hatching and attachment were not affected at any concentration. The frequency of SCEs was significantly increased at ? 1 × 10?6 M. When egg cyclinders were treated with K2Cr2O7 for 24 hours, the number of embryos with blood islands, fusion of the allantois with the chorion, and beating heart was significantly reduced at all concentrations tested, and the crown-rump lengths of embryos were significantly reduced at 1 to 2 × 10?6 M. The frequency of SCEs was increased in embryonic tissues of egg cylinders cultured in ? 1 × 10?6 M K2Cr2O7. Increased SCE frequencies were observed at lower concentrations in extraembryonic tissues, which had higher SCE frequencies than embryonic tissues at all concentrations tested. The correlation between developmental effects and SCE frequency suggests that cytogenetic damage may be largely responsible for the detrimental effects of dichromate on mouse embryos.","Developmental and cytogenetic effects of potassium dichromate on mouse embryos in vitro Abs: Mouse blastocysts and egg cylinders were treated in vitro with potassium dichromate (K2Cr2O7, 5 × 10?7 to 2 × 10?6 M), and the effects on postimplantation development and induction of sister chromatid exchanges (SCEs) were determined. When blastocysts were treated for six days with 1 × 10?6 M K2Cr2O7, the number of embryos with growing inner cell masses (ICMs) and ICMs that were differentiated into primary endoderm and ectoderm were significantly reduced. The number of embryos forming trophoblast outgrowths was not reduced, but outgrowth formed in the presence of 2 × 10?6 M K2Cr2O7 were small and began to degenerate by the end of the treatment. Hatching and attachment were not affected at any concentration. The frequency of SCEs was significantly increased at ? 1 × 10?6 M. When egg cyclinders were treated with K2Cr2O7 for 24 hours, the number of embryos with blood islands, fusion of the allantois with the chorion, and beating heart was significantly reduced at all concentrations tested, and the crown-rump lengths of embryos were significantly reduced at 1 to 2 × 10?6 M. The frequency of SCEs was increased in embryonic tissues of egg cylinders cultured in ? 1 × 10?6 M K2Cr2O7. Increased SCE frequencies were observed at lower concentrations in extraembryonic tissues, which had higher SCE frequencies than embryonic tissues at all concentrations tested. The correlation between developmental effects and SCE frequency suggests that cytogenetic damage may be largely responsible for the detrimental effects of dichromate on mouse embryos."
1234968,Flos et al. 1983,Chromium and potassium accumulation influenced by body weight in goldfish (Carassius auratus),,Chromium and potassium accumulation influenced by body weight in goldfish (Carassius auratus) Abs: 
1234965,Bianchi et al. 1983,Genetic effects of chromium compounds,"Seven different test systems were utilized to investigate the genetic activity of chromium compounds: infidelity of DNA replication in vitro by DNA pol alpha from calf thymus, damage of DNA detected by alkaline elution in treated mammalian cells or in DNA purified and treated in vitro, DNA repair synthesis in mammalian cells in vitro detected by autoradiography or scintillation counting after labelling with [3H]dThd, gene mutations in the Salmonella typhimurium Ames test, gene mutations (6TG resistance) in cultured hamster cells, sister-chromatid exchanges in different rodent cell cultures, and transformation to anchorage-independent growth of hamster cells in vitro (soft-agar assay). Potassium dichromate and chromium chloride were used as water-soluble Cr(VI) and Cr(III) salts. Several reference mutagens (EMS, MMS, MMC, 4NQO) were included in the single tests as positive controls. Cr(VI) was active in all the tested systems, except in the induction of DNA damage and DNA repair synthesis in cultured cells. Cr(III), on the other hand, was absolutely inactive unless a direct interaction with purified DNA was permitted by the test conditions. The relevance of data from the various tests to the understanding of the mechanisms of the genotoxic activity of chromium is discussed. Effects other than the direct interaction of Cr(III) with DNA are inferred, which can cause infidelity of the DNA polymerase functions.","Genetic effects of chromium compounds Abs: Seven different test systems were utilized to investigate the genetic activity of chromium compounds: infidelity of DNA replication in vitro by DNA pol alpha from calf thymus, damage of DNA detected by alkaline elution in treated mammalian cells or in DNA purified and treated in vitro, DNA repair synthesis in mammalian cells in vitro detected by autoradiography or scintillation counting after labelling with [3H]dThd, gene mutations in the Salmonella typhimurium Ames test, gene mutations (6TG resistance) in cultured hamster cells, sister-chromatid exchanges in different rodent cell cultures, and transformation to anchorage-independent growth of hamster cells in vitro (soft-agar assay). Potassium dichromate and chromium chloride were used as water-soluble Cr(VI) and Cr(III) salts. Several reference mutagens (EMS, MMS, MMC, 4NQO) were included in the single tests as positive controls. Cr(VI) was active in all the tested systems, except in the induction of DNA damage and DNA repair synthesis in cultured cells. Cr(III), on the other hand, was absolutely inactive unless a direct interaction with purified DNA was permitted by the test conditions. The relevance of data from the various tests to the understanding of the mechanisms of the genotoxic activity of chromium is discussed. Effects other than the direct interaction of Cr(III) with DNA are inferred, which can cause infidelity of the DNA polymerase functions."
1234964,Nilsson et al. 1983,Structure of oligosaccharides and the linkage region between keratan sulfate and the core protein on proteoglycans from monkey cornea,"Structural analyses were performed on the intact glycopeptides and on the linkage region oligosaccharide-peptides derived from the keratan sulfate proteoglycan from monkey cornea (Nakazawa, K., Newsome, D.A., Nilsson, B., Hascall, V.C., and Hassell, J.R. (1983) J. Biol. Chem. 258, 6051-6055) using trifluoroacetolysis, Smith degradation, chromium trioxide oxidation, and gas-liquid chromatography-mass spectrometry. The following structure was found for the linkage region (formula; see text) The following structures were found for the intact oligosaccharide peptides (formula; see text) and (formula; see text) The structure of the linkage region for keratan sulfate on corneal proteoglycans is clearly derived from a complex type of N-linked glycoprotein oligosaccharide precursor, indicating that only the oligosaccharides that have been processed to the complex type are used as primers for synthesizing keratan sulfate chains. The high mannose oligosaccharide in Formula 3 is an intermediate in the normal pathway for biosynthesis of complex type oligosaccharides. The structure in Formula 2, in which a single Man alpha 1-2 is retained on the Man alpha 1-3 branch while the Man alpha 1-6 branch is unsubstituted, can be an intermediate for an alternate, presumably minor pathway for complex oligosaccharide formation (Kornfeld, S., Gregory, W., and Chapman, A. (1979) J. Biol. Chem. 254, 11649-11654) in certain cases. This structure has not previously been shown to be present on normal glycoproteins.","Structure of oligosaccharides and the linkage region between keratan sulfate and the core protein on proteoglycans from monkey cornea Abs: Structural analyses were performed on the intact glycopeptides and on the linkage region oligosaccharide-peptides derived from the keratan sulfate proteoglycan from monkey cornea (Nakazawa, K., Newsome, D.A., Nilsson, B., Hascall, V.C., and Hassell, J.R. (1983) J. Biol. Chem. 258, 6051-6055) using trifluoroacetolysis, Smith degradation, chromium trioxide oxidation, and gas-liquid chromatography-mass spectrometry. The following structure was found for the linkage region (formula; see text) The following structures were found for the intact oligosaccharide peptides (formula; see text) and (formula; see text) The structure of the linkage region for keratan sulfate on corneal proteoglycans is clearly derived from a complex type of N-linked glycoprotein oligosaccharide precursor, indicating that only the oligosaccharides that have been processed to the complex type are used as primers for synthesizing keratan sulfate chains. The high mannose oligosaccharide in Formula 3 is an intermediate in the normal pathway for biosynthesis of complex type oligosaccharides. The structure in Formula 2, in which a single Man alpha 1-2 is retained on the Man alpha 1-3 branch while the Man alpha 1-6 branch is unsubstituted, can be an intermediate for an alternate, presumably minor pathway for complex oligosaccharide formation (Kornfeld, S., Gregory, W., and Chapman, A. (1979) J. Biol. Chem. 254, 11649-11654) in certain cases. This structure has not previously been shown to be present on normal glycoproteins."
1234963,Garcia et al. 1983,Techniques for the recovery and identification of Cryptosporidium oocysts from stool specimens,"Due to increasing numbers of patients with documented infections with Cryptosporidium and other coccidia, it is important for the physician and clinical laboratory to be aware of the appropriate diagnostic techniques necessary for organism recovery and identification. Although Cryptosporidium is found in the gastrointestinal tract, tissue biopsies may be insufficient for organism recovery; the examination of stool specimens is a noninvasive procedure and will provide better overall opportunities for organism recovery. Human clinical specimens were examined from 45 patients with confirmed cryptosporidiosis or suspected of having the infection. Tissue biopsy sections, fecal wet preparations, and permanent stained smears were examined. Stool specimens were submitted in 10% Formalin, 2.5% potassium dichromate, and polyvinyl alcohol and were examined for oocysts by using 15 different methods: phase-contrast and light microscopy; Sheather's sugar flotation; Formalin concentration techniques; 10% potassium hydroxide; Giemsa; trichrome; periodic acid-Schiff; modified periodic acid-Schiff; silver methenamine; acridine orange; auramine-rhodamine; Kinyoun acid-fast; Ziehl-Neelsen carbolfuchsin; and a modified acid-fast procedure. Each technique or combination of techniques was assessed by organism quantitation, organism morphology, and ease of visual recognition. Based on these comparative studies, the modified Ziehl-Neelsen carbolfuchsin stain on 10% Formalin-preserved stool is recommended for the recovery and identification of Cryptosporidium.","Techniques for the recovery and identification of Cryptosporidium oocysts from stool specimens Abs: Due to increasing numbers of patients with documented infections with Cryptosporidium and other coccidia, it is important for the physician and clinical laboratory to be aware of the appropriate diagnostic techniques necessary for organism recovery and identification. Although Cryptosporidium is found in the gastrointestinal tract, tissue biopsies may be insufficient for organism recovery; the examination of stool specimens is a noninvasive procedure and will provide better overall opportunities for organism recovery. Human clinical specimens were examined from 45 patients with confirmed cryptosporidiosis or suspected of having the infection. Tissue biopsy sections, fecal wet preparations, and permanent stained smears were examined. Stool specimens were submitted in 10% Formalin, 2.5% potassium dichromate, and polyvinyl alcohol and were examined for oocysts by using 15 different methods: phase-contrast and light microscopy; Sheather's sugar flotation; Formalin concentration techniques; 10% potassium hydroxide; Giemsa; trichrome; periodic acid-Schiff; modified periodic acid-Schiff; silver methenamine; acridine orange; auramine-rhodamine; Kinyoun acid-fast; Ziehl-Neelsen carbolfuchsin; and a modified acid-fast procedure. Each technique or combination of techniques was assessed by organism quantitation, organism morphology, and ease of visual recognition. Based on these comparative studies, the modified Ziehl-Neelsen carbolfuchsin stain on 10% Formalin-preserved stool is recommended for the recovery and identification of Cryptosporidium."
1234962,Roy 1983,Visualization of Legionella pneumophila in paraffin sections using hexamine silver,"A modification of Gomori's hexamine silver technique is given as a simple, reliable method for the nonspecific demonstration of Legionella pneumophila in paraffin sections. When tested against serogroups I to VI it was found that pretreatment with potassium dichromate rendered L. pneumophila demonstrable by the Gomori-Burtner hexamine silver solution when buffered to pH 7.8. Tissue was fixed in 10% buffered formalin and sections were cut at 3-5 microns. After treatment with 10% potassium dichromate for 1 hour at room temperature, sections are placed in the silver solution at 56 C until they develop a pale golden yellow color, at which point they are checked periodically under the microscope for optimal staining (approximately 3-4 hours). Sections are then toned, fixed and counterstained in 1% neutral red. The L. pneumophila coccobacilli stain black against a clear background, while nuclei stain red/black.","Visualization of Legionella pneumophila in paraffin sections using hexamine silver Abs: A modification of Gomori's hexamine silver technique is given as a simple, reliable method for the nonspecific demonstration of Legionella pneumophila in paraffin sections. When tested against serogroups I to VI it was found that pretreatment with potassium dichromate rendered L. pneumophila demonstrable by the Gomori-Burtner hexamine silver solution when buffered to pH 7.8. Tissue was fixed in 10% buffered formalin and sections were cut at 3-5 microns. After treatment with 10% potassium dichromate for 1 hour at room temperature, sections are placed in the silver solution at 56 C until they develop a pale golden yellow color, at which point they are checked periodically under the microscope for optimal staining (approximately 3-4 hours). Sections are then toned, fixed and counterstained in 1% neutral red. The L. pneumophila coccobacilli stain black against a clear background, while nuclei stain red/black."
1234958,Murti et al. 1983,Chromium toxicity to a freshwater prawn Macrobrachium lamarrei (H.M. Edwards),"Experiments were carried out to determine the short-term toxicity of potassium dichromate (K2Cr2O7) to Macrobrachium lamarrei (M. Edwards) and the effect of acute and sub-acute concentrations on haemolymph glucose level of the animal. The LC50 values for 24, 48, 72 and 96 h were 5.44, 3.69, 2.47 and 1.84 mg/l, respectively. Exposure of K2Cr2O7 decreased the haemolymph glucose level up to 24 h but thereafter an increase in haemolymph glucose level was observed that continued up to 72 h. The haemolymph glucose level decreased after 96 h. The effects of K2Cr2O7 in relation to these changes and mortality of organisms were also discussed.","Chromium toxicity to a freshwater prawn Macrobrachium lamarrei (H.M. Edwards) Abs: Experiments were carried out to determine the short-term toxicity of potassium dichromate (K2Cr2O7) to Macrobrachium lamarrei (M. Edwards) and the effect of acute and sub-acute concentrations on haemolymph glucose level of the animal. The LC50 values for 24, 48, 72 and 96 h were 5.44, 3.69, 2.47 and 1.84 mg/l, respectively. Exposure of K2Cr2O7 decreased the haemolymph glucose level up to 24 h but thereafter an increase in haemolymph glucose level was observed that continued up to 72 h. The haemolymph glucose level decreased after 96 h. The effects of K2Cr2O7 in relation to these changes and mortality of organisms were also discussed."
1234957,Wada et al. 1983,"Purification and chromium-excretory function of low-molecular-weight, chromium-binding substances from dog liver","From liver of dogs injected iv with potassium dichromate (38 mg/kg body wt), a low-molecular-weight chromium-binding substance (LMCr) was purified into two subfractions, LMCr I and LMCr II, which differ in physical and chemical properties. LMCr I was identified to be an anionic, organic chromium compound with a molecular weight of 1500. It contained glutamic acid, glycine, and cysteine as the predominant amino acids and firmly bound chromium in a ratio of one chromium(III) to one molecule of LMCr I. LMCr II was isolated in crystalline form and demonstrated to be a water-soluble, inorganic chromium(III) complex consisting of Na2HPO4 . 7H2O and Na2HPO4 . 2H2O. Although its crystallization reduced the chromium content, it had a maximum chromium-binding capacity as much as one chromium per one phosphorus in water. The mixture of LMCr I and LMCr II as approximated to be the natural composition showed a lower acute toxicity as measured by lethality in mice and had higher rates of urinary excretion and renal clearance in rabbits, accompanied by lower rates of renal tubular reabsorption and retention in kidney and liver than potassium dichromate(VI) and chromium(III) chloride. Pretreatment with chromium-free LMCr II remarkably reduced the mortality rates of mice acutely poisoned with chromium chloride. These results indicate that LMCr plays an important role in the detoxification and excretion of chromium in mammals.","Purification and chromium-excretory function of low-molecular-weight, chromium-binding substances from dog liver Abs: From liver of dogs injected iv with potassium dichromate (38 mg/kg body wt), a low-molecular-weight chromium-binding substance (LMCr) was purified into two subfractions, LMCr I and LMCr II, which differ in physical and chemical properties. LMCr I was identified to be an anionic, organic chromium compound with a molecular weight of 1500. It contained glutamic acid, glycine, and cysteine as the predominant amino acids and firmly bound chromium in a ratio of one chromium(III) to one molecule of LMCr I. LMCr II was isolated in crystalline form and demonstrated to be a water-soluble, inorganic chromium(III) complex consisting of Na2HPO4 . 7H2O and Na2HPO4 . 2H2O. Although its crystallization reduced the chromium content, it had a maximum chromium-binding capacity as much as one chromium per one phosphorus in water. The mixture of LMCr I and LMCr II as approximated to be the natural composition showed a lower acute toxicity as measured by lethality in mice and had higher rates of urinary excretion and renal clearance in rabbits, accompanied by lower rates of renal tubular reabsorption and retention in kidney and liver than potassium dichromate(VI) and chromium(III) chloride. Pretreatment with chromium-free LMCr II remarkably reduced the mortality rates of mice acutely poisoned with chromium chloride. These results indicate that LMCr plays an important role in the detoxification and excretion of chromium in mammals."
1234953,Miyajima et al. 1983,Relationships between histological and functional indices of acute chemically induced nephrotoxicity,"Acute renal injury was produced in rats with K2Cr2O7 (5-40 mg/kg, sc) HgCl2 (0.5-5.0 mg/kg, sc) or cephaloridine (0.5-3.0 g/kg, sc). Histological (percentage of normal, degenerated or necrotic cells) and functional indices (relative kidney weight, renal cortical slice accumulation of organic ions, and blood urea nitrogen content) were evaluated 48 hours later. The relative sensitivity of each of these indices was determined for each nephrotoxicant. Renal cortical accumulation of organic ions appeared to be the most sensitive of the functional parameters. A quantitative histological evaluation was found to be as sensitive an indicator of nephrotoxicity as organic ion accumulation. Alterations in each of the functional indices were significantly correlated with changes in renal histology.","Relationships between histological and functional indices of acute chemically induced nephrotoxicity Abs: Acute renal injury was produced in rats with K2Cr2O7 (5-40 mg/kg, sc) HgCl2 (0.5-5.0 mg/kg, sc) or cephaloridine (0.5-3.0 g/kg, sc). Histological (percentage of normal, degenerated or necrotic cells) and functional indices (relative kidney weight, renal cortical slice accumulation of organic ions, and blood urea nitrogen content) were evaluated 48 hours later. The relative sensitivity of each of these indices was determined for each nephrotoxicant. Renal cortical accumulation of organic ions appeared to be the most sensitive of the functional parameters. A quantitative histological evaluation was found to be as sensitive an indicator of nephrotoxicity as organic ion accumulation. Alterations in each of the functional indices were significantly correlated with changes in renal histology."
1234950,Paschin et al. 1983,Differential mutagenic response at the HGPRT locus in V79 and CHO Chinese hamster cells after treatment with chromate,,Differential mutagenic response at the HGPRT locus in V79 and CHO Chinese hamster cells after treatment with chromate Abs: 
1234949,Christie and  Hansen 1983,Cytochemical evidence for the existence of norepinephrine-containing glomus cells in the rat carotid body,"Some investigators have postulated that glomus cells of the rat carotid body contain only dopamine (DA), and that the norepinephrine (NE) measured in the carotid body resides only in sympathetic nerve endings and ganglion cells. To investigate this hypothesis, we employed a pharmacologic drug sequence which depleted all carotid body catecholamines and then selectively restored DA levels while keeping NE levels significantly lowered. Analysis of carotid body catecholamines by high performance liquid chromatography (HPLC) validated this drug regimen. Employing this drug treatment, we examined glomus cells after potassium dichromate cytochemical staining in an effort to distinguish those glomus cell vesicles which still contained appreciable amounts of catecholamine, presumably DA. Glomus cells from rats receiving vehicle or L-dopa (100 mg kg-1 ip) alone had 83 and 97% of their cells stained, respectively. However, glomus cells from reserpinized (5 mg kg-1 ip) animals were largely unstained (89%). Carotid bodies from animals treated with reserpine and then, 24 h later, with L-dopa 90 min prior to sacrifice had about 46% of their glomus cells stained while 54% of the cells were unstained. The results of this last group, coupled with our biochemical data which demonstrated that DA levels were comparable to control values but that NE was 80% depleted, suggest that a significant number of glomus cells did not contain enough catecholamine to react with the dichromate. We believe that these unstained cells may normally contain NE and that glomus cells may be of several types, some containing predominantly DA and others NE.","Cytochemical evidence for the existence of norepinephrine-containing glomus cells in the rat carotid body Abs: Some investigators have postulated that glomus cells of the rat carotid body contain only dopamine (DA), and that the norepinephrine (NE) measured in the carotid body resides only in sympathetic nerve endings and ganglion cells. To investigate this hypothesis, we employed a pharmacologic drug sequence which depleted all carotid body catecholamines and then selectively restored DA levels while keeping NE levels significantly lowered. Analysis of carotid body catecholamines by high performance liquid chromatography (HPLC) validated this drug regimen. Employing this drug treatment, we examined glomus cells after potassium dichromate cytochemical staining in an effort to distinguish those glomus cell vesicles which still contained appreciable amounts of catecholamine, presumably DA. Glomus cells from rats receiving vehicle or L-dopa (100 mg kg-1 ip) alone had 83 and 97% of their cells stained, respectively. However, glomus cells from reserpinized (5 mg kg-1 ip) animals were largely unstained (89%). Carotid bodies from animals treated with reserpine and then, 24 h later, with L-dopa 90 min prior to sacrifice had about 46% of their glomus cells stained while 54% of the cells were unstained. The results of this last group, coupled with our biochemical data which demonstrated that DA levels were comparable to control values but that NE was 80% depleted, suggest that a significant number of glomus cells did not contain enough catecholamine to react with the dichromate. We believe that these unstained cells may normally contain NE and that glomus cells may be of several types, some containing predominantly DA and others NE."
1234947,Wong 1984,The determination of the triazolobenzodiazepine triazolam in post mortem samples,"A post mortem case involving the triazolobenzodiazepine triazolam is reported. Levels of 38 ng/g in the liver and 6.7 ng/mL in the blood were determined by reversed-phase high-performance liquid chromatography (HPLC) using an eluent of 0.06% acetic acid:acetonitrile (61:39) and ultraviolet detection at 221 nm. The presence of triazolam in the post mortem samples was verified by its oxidation to a benzophenone with potassium dichromate, followed by the analysis of the oxidized extract by HPLC using a silica column and an eluent of dichloromethane:methanol (97.5:2.5) at 250 nm.","The determination of the triazolobenzodiazepine triazolam in post mortem samples Abs: A post mortem case involving the triazolobenzodiazepine triazolam is reported. Levels of 38 ng/g in the liver and 6.7 ng/mL in the blood were determined by reversed-phase high-performance liquid chromatography (HPLC) using an eluent of 0.06% acetic acid:acetonitrile (61:39) and ultraviolet detection at 221 nm. The presence of triazolam in the post mortem samples was verified by its oxidation to a benzophenone with potassium dichromate, followed by the analysis of the oxidized extract by HPLC using a silica column and an eluent of dichloromethane:methanol (97.5:2.5) at 250 nm."
1234946,Nordlind and  Henze 1984,"Investigation of ability of the metal allergens cobalt chloride, nickel sulfate and potassium dichromate to give a mitogenic response in human thymocytes","The metal allergens cobalt chloride, nickel sulfate and potassium dichromate were tested for the ability to give a mitogenic response in human thymocytes, both unseparated and Percoll-separated, including a fraction of low density, which has been shown to have characteristics of medullary cells (unsensitized, virgin T cells). With cobalt chloride and potassium dichromate, no stimulation occurred; instead, cobalt chloride at a concentration of 3.5 X 10(-5) M and potassium dichromate at 5.7 X 10(-7) M were inhibiting. After nickel sulfate addition, a small DNA synthesis stimulation was obtained in both unseparated cells and in fractionated cells of different densities. The results thus speak against that cobalt chloride and potassium dichromate are unspecific mitogens for human lymphoid cells, while an unspecific mitogenic effect is indicated for nickel sulfate.","Investigation of ability of the metal allergens cobalt chloride, nickel sulfate and potassium dichromate to give a mitogenic response in human thymocytes Abs: The metal allergens cobalt chloride, nickel sulfate and potassium dichromate were tested for the ability to give a mitogenic response in human thymocytes, both unseparated and Percoll-separated, including a fraction of low density, which has been shown to have characteristics of medullary cells (unsensitized, virgin T cells). With cobalt chloride and potassium dichromate, no stimulation occurred; instead, cobalt chloride at a concentration of 3.5 X 10(-5) M and potassium dichromate at 5.7 X 10(-7) M were inhibiting. After nickel sulfate addition, a small DNA synthesis stimulation was obtained in both unseparated cells and in fractionated cells of different densities. The results thus speak against that cobalt chloride and potassium dichromate are unspecific mitogens for human lymphoid cells, while an unspecific mitogenic effect is indicated for nickel sulfate."
1234945,Lavelle and  Witmer 1984,Chromium (VI) potentiates mutagenesis by sodium azide but not ethyl methanesulfonate,"A fluctuation test using Salmonella typhimurium strain 1535 has been used in an experimental protocol to assess biological effects of interactions between chromium (VI), such as K2CrO4, and two DNA-damaging agents, ethyl methanesulfonate (EMS), and sodium azide. Mutagenicity, expressed as the average number of mutations induced over a parallel control, was determined for the compounds alone and in combination. The significance of the differences between the &quot;expected&quot; response, calculated by simple addition of the responses from the individual tests, and the observed response when the combination was tested, were estimated by chi square. For the combination of K2CrO4 and NaN3, the response was significantly greater than expected suggesting a possible potentiation of mutagenesis. The opposite (a less-than-additive response) was found for the K2CrO4/EMS combination. Both effects were found to be dose related to the concentration of potassium chromate used. Toxicity of the compounds or their combinations to the bacteria could not explain the results.","Chromium (VI) potentiates mutagenesis by sodium azide but not ethyl methanesulfonate Abs: A fluctuation test using Salmonella typhimurium strain 1535 has been used in an experimental protocol to assess biological effects of interactions between chromium (VI), such as K2CrO4, and two DNA-damaging agents, ethyl methanesulfonate (EMS), and sodium azide. Mutagenicity, expressed as the average number of mutations induced over a parallel control, was determined for the compounds alone and in combination. The significance of the differences between the &quot;expected&quot; response, calculated by simple addition of the responses from the individual tests, and the observed response when the combination was tested, were estimated by chi square. For the combination of K2CrO4 and NaN3, the response was significantly greater than expected suggesting a possible potentiation of mutagenesis. The opposite (a less-than-additive response) was found for the K2CrO4/EMS combination. Both effects were found to be dose related to the concentration of potassium chromate used. Toxicity of the compounds or their combinations to the bacteria could not explain the results."
1234943,Graf von Keyserlingk and  Schramm 1984,Diameter of axons and thickness of myelin sheaths of the pyramidal tract fibres in the adult human medullary pyramid,"After perfusion fixation with a mixture of paraformaldehyde, glutaraldehyde, and potassium-chromate 4 adult human medullary pyramids were examined with the electron microscope. The myelin sheaths showed only mild signs of post mortal destructions. The periodicity of the lamellae is preserved and varies about 17 nm. For quantitative purposes specimens were taken at random from regions with an extend of half a mm2 on the cross section of the pyramid. On the average 62 lamellae (s = 5, n = 200) built up 1 micron myelin sheath in the 4 brains. The myelin sheath thickness and the inner circumference of the myelin sheath are measured. The axon diameter is calculated from the inner circumference. We obtained an average number of 66,000 fibres, s = 11,000 per mm2. Fibres with a total diameter below 4 microns amount to 87.9%, fibres from 4 to 10 microns to 10.77%, and larger than 10 microns to 1.4%. An axon diameter of about 0.5 micron combined with a thickness of the myelin sheath of 0.3 micron was most often found in all 4 cases. The fibres showed a broad variation of myelin thickness. In a given group of the small axons the thickest myelin sheath exceeded 3 to 4 times the value of the thinnest one. The coefficient of correlation between axon diameter and myelin sheath thickness was calculated as r2 = 0.56. No correspondence exists between frequency maxima and the ratio g, axon diameter to total diameter. Below a total fibre diameter of 5 microns the ratio g scatters broadly about 0.6, fibres larger than 5 microns exceed the value of 0.6. From the morphological data only large sized fibres can evoke a strong effect on compound action potentials if the method of reconstruction of the action potential from fibre size frequency distribution is employed.","Diameter of axons and thickness of myelin sheaths of the pyramidal tract fibres in the adult human medullary pyramid Abs: After perfusion fixation with a mixture of paraformaldehyde, glutaraldehyde, and potassium-chromate 4 adult human medullary pyramids were examined with the electron microscope. The myelin sheaths showed only mild signs of post mortal destructions. The periodicity of the lamellae is preserved and varies about 17 nm. For quantitative purposes specimens were taken at random from regions with an extend of half a mm2 on the cross section of the pyramid. On the average 62 lamellae (s = 5, n = 200) built up 1 micron myelin sheath in the 4 brains. The myelin sheath thickness and the inner circumference of the myelin sheath are measured. The axon diameter is calculated from the inner circumference. We obtained an average number of 66,000 fibres, s = 11,000 per mm2. Fibres with a total diameter below 4 microns amount to 87.9%, fibres from 4 to 10 microns to 10.77%, and larger than 10 microns to 1.4%. An axon diameter of about 0.5 micron combined with a thickness of the myelin sheath of 0.3 micron was most often found in all 4 cases. The fibres showed a broad variation of myelin thickness. In a given group of the small axons the thickest myelin sheath exceeded 3 to 4 times the value of the thinnest one. The coefficient of correlation between axon diameter and myelin sheath thickness was calculated as r2 = 0.56. No correspondence exists between frequency maxima and the ratio g, axon diameter to total diameter. Below a total fibre diameter of 5 microns the ratio g scatters broadly about 0.6, fibres larger than 5 microns exceed the value of 0.6. From the morphological data only large sized fibres can evoke a strong effect on compound action potentials if the method of reconstruction of the action potential from fibre size frequency distribution is employed."
1234939,Congiu et al. 1984,Effects of metal ions and CCl4 on sea urchin embryo (Paracentrotus lividus),"The determination of embryotoxicity is an experimental tool for detecting the risks of environmental pollutants. In this study, fertilized eggs of sea urchin have been observed morphologically during exposure to heavy metal salts or carbon tetrachloride, with the purpose of testing possible differences in toxicity of various classes of poisons. Mercuric chloride is the most active salt, still harmful at 0.25 x 10(-6) M, while potassium dichromate, cadmium chloride and lead nitrate block embryo development at concentrations ranging between 0.25 x 10(-4) and 0.25 x 10(-5) M. Carbon tetrachloride per se does not affect the gastrulation at concentrations up to 3,520 ppm, and fails in potentiating the toxicity of the studied metal salts. The selective susceptibility of the development phases of sea urchin embryos to different compounds renders this simple morphological study a sensitive and reliable model for predicting the toxicity of environmental pollutants.","Effects of metal ions and CCl4 on sea urchin embryo (Paracentrotus lividus) Abs: The determination of embryotoxicity is an experimental tool for detecting the risks of environmental pollutants. In this study, fertilized eggs of sea urchin have been observed morphologically during exposure to heavy metal salts or carbon tetrachloride, with the purpose of testing possible differences in toxicity of various classes of poisons. Mercuric chloride is the most active salt, still harmful at 0.25 x 10(-6) M, while potassium dichromate, cadmium chloride and lead nitrate block embryo development at concentrations ranging between 0.25 x 10(-4) and 0.25 x 10(-5) M. Carbon tetrachloride per se does not affect the gastrulation at concentrations up to 3,520 ppm, and fails in potentiating the toxicity of the studied metal salts. The selective susceptibility of the development phases of sea urchin embryos to different compounds renders this simple morphological study a sensitive and reliable model for predicting the toxicity of environmental pollutants."
1234938,Barber and  Cronin 1984,Patch and photopatch testing in chronic actinic dermatitis,"Photopatch tests in 47 patients with chronic actinic dermatitis (CAD) showed musk ambrette to be the only significant allergen in our standard photopatch test series. The incidence of positive patch tests to a standard series of contact allergens in this group was compared with 213 men over the age of 50 years with eczema investigated in the contact clinic. Among the photosensitive patients, there was an increased incidence of reaction to thiuram-mix (CAD 10%; controls 3%), carba mix (CAD 6%; controls 1%), nickel sulphate (CAD 6%; controls 2%) and vioform (CAD 10%; controls 0.5%). A decreased incidence of reaction to potassium dichromate (CAD 0%; controls 8%) and balsam of Peru (CAD 4%; controls 10%) was recorded.","Patch and photopatch testing in chronic actinic dermatitis Abs: Photopatch tests in 47 patients with chronic actinic dermatitis (CAD) showed musk ambrette to be the only significant allergen in our standard photopatch test series. The incidence of positive patch tests to a standard series of contact allergens in this group was compared with 213 men over the age of 50 years with eczema investigated in the contact clinic. Among the photosensitive patients, there was an increased incidence of reaction to thiuram-mix (CAD 10%; controls 3%), carba mix (CAD 6%; controls 1%), nickel sulphate (CAD 6%; controls 2%) and vioform (CAD 10%; controls 0.5%). A decreased incidence of reaction to potassium dichromate (CAD 0%; controls 8%) and balsam of Peru (CAD 4%; controls 10%) was recorded."
1234937,Lantinga et al. 1984,"Prevalence, incidence and course of eczema on the hands and forearms in a sample of the general population","In 1979, the inhabitants of a geographically defined area were examined for skin disorders of the hands and forearms. In 1982 this cohort was invited for re-examination. In persons with eczema, patch testing was performed. Irritant factors were found to play a rôle in 73% of the cases, whereas a contact allergy could be detected in 30%. The most frequent allergens were nickel sulphate (20%), potassium dichromate (6%) and cobalt chloride (4%). In some persons with a definite history of allergy to metals, no positive patch test with nickel, chromate or cobalt could be obtained; other mechanisms may be involved. Significantly more positive patch tests were found among persons with an eczema of longer than 2 years duration compared with persons with eczema present for a shorter period of time, indicating that many cases of eczema are primarily of irritant nature, but later complicated by sensitisation. In 41%, the eczema was healed. A poor healing tendency was observed in those with a combination of irritant and allergic eczema. Relatively few ascribed healing to medical treatment.","Prevalence, incidence and course of eczema on the hands and forearms in a sample of the general population Abs: In 1979, the inhabitants of a geographically defined area were examined for skin disorders of the hands and forearms. In 1982 this cohort was invited for re-examination. In persons with eczema, patch testing was performed. Irritant factors were found to play a rôle in 73% of the cases, whereas a contact allergy could be detected in 30%. The most frequent allergens were nickel sulphate (20%), potassium dichromate (6%) and cobalt chloride (4%). In some persons with a definite history of allergy to metals, no positive patch test with nickel, chromate or cobalt could be obtained; other mechanisms may be involved. Significantly more positive patch tests were found among persons with an eczema of longer than 2 years duration compared with persons with eczema present for a shorter period of time, indicating that many cases of eczema are primarily of irritant nature, but later complicated by sensitisation. In 41%, the eczema was healed. A poor healing tendency was observed in those with a combination of irritant and allergic eczema. Relatively few ascribed healing to medical treatment."
1234936,van Ketel 1984,Low incidence of occupational dermatitis from chromate,HEEP COPYRIGHT: BIOL ABS. RRM HUMAN POTASSIUM DI CHROMATE MARGINAL IRRITANT PATCH TEST READING,Low incidence of occupational dermatitis from chromate Abs: HEEP COPYRIGHT: BIOL ABS. RRM HUMAN POTASSIUM DI CHROMATE MARGINAL IRRITANT PATCH TEST READING
1234935,Valsecchi and  Cainelli 1984,Chromium dermatitis and ascorbic acid,"The case was described of a 52 year old radiologist with a long history of contact dermatitis, manifested by increasingly severe itching, swelling, weeping and fissuring of the hands and wrists. During his working hours the radiologist handled radiograms, fixatives, and photographic dish cleaners, without the use of protective gloves or barrier creams. During weekends and holidays, the condition of the patient improved with steroids and wet dressings. After patch tests revealed a positive reaction to potassium-dichromate (7778509), the patient was prescribed an ointment containing 10 percent ascorbic-acid (50817) which he applied three times a day during working hours. Dramatic symptomatic improvement was recorded within 3 weeks of treatment, without requiring the additional use of wet dressings or topical application of steroids, and total recovery was evident at the end of 2 months. The subsequent recurrence of occasional flareups was treated by the application of a steroid cream. Upon the discontinuation of the ascorbic-acid ointment after 15 months of treatment, the patient's hands were free of eczema and the chromate skin test became negative, although he continued to handle the same materials without changing his working habits. The authors conclude that the application of ascorbic-acid ointment could induce desensitization to chromate.","Chromium dermatitis and ascorbic acid Abs: The case was described of a 52 year old radiologist with a long history of contact dermatitis, manifested by increasingly severe itching, swelling, weeping and fissuring of the hands and wrists. During his working hours the radiologist handled radiograms, fixatives, and photographic dish cleaners, without the use of protective gloves or barrier creams. During weekends and holidays, the condition of the patient improved with steroids and wet dressings. After patch tests revealed a positive reaction to potassium-dichromate (7778509), the patient was prescribed an ointment containing 10 percent ascorbic-acid (50817) which he applied three times a day during working hours. Dramatic symptomatic improvement was recorded within 3 weeks of treatment, without requiring the additional use of wet dressings or topical application of steroids, and total recovery was evident at the end of 2 months. The subsequent recurrence of occasional flareups was treated by the application of a steroid cream. Upon the discontinuation of the ascorbic-acid ointment after 15 months of treatment, the patient's hands were free of eczema and the chromate skin test became negative, although he continued to handle the same materials without changing his working habits. The authors conclude that the application of ascorbic-acid ointment could induce desensitization to chromate."
1234934,Mochrie and  Dickey 1984,Comparison of semiautomated method with official optical somatic cell counting method III for determining somatic cells in milk,"The new method specifying the Fossomatic-90 differs from the official method, 46.105-46.109, in that the modified instrument includes a halogen lamp; a semiconductor photoelectric detector; a less expensive, bench-top cabinet; manual injection of a larger sample, and a reduced capacity. The new instrument was compared with 2 optical somatic cell counters in routine use. On each of 3 days, 12 subsamples were prepared for each of 5 cell count levels from AM milk with half kept fresh and half preserved with 0.05% potassium dichromate. Subsamples were refrigerated and read 30+ h post-collection. Duplicate sets were read in random order on each machine daily (CV 0.77%). Two sets of slides read by 2 technicians each (strip reticle on 2 smears/slide) gave geometric mean direct microscopic somatic cell count (DMSCC) levels of 296, 526, 772, 930, and 1438 th/mL. Within-technician CV values (from day-level means) ranged from 1.68 to 2.28%. Geometric mean cells in th/mL on the new machine were significantly higher than those on the other two (674 vs 621) and were closer to the DMSCC (694). On the new machine, cell counts were 8.5% greater than on the original machines, were only 2.9% lower than the DMSCC, and showed no significant evidence of bias. Preserved samples averaged slightly greater than fresh (5.3%) but only on the original machines. Carryover by covariance analysis was insignificant. Except for cell levels, high machine precision (error CV value of 1.18%) gave differences with statistical but not practical significance, even for regulatory laboratories.","Comparison of semiautomated method with official optical somatic cell counting method III for determining somatic cells in milk Abs: The new method specifying the Fossomatic-90 differs from the official method, 46.105-46.109, in that the modified instrument includes a halogen lamp; a semiconductor photoelectric detector; a less expensive, bench-top cabinet; manual injection of a larger sample, and a reduced capacity. The new instrument was compared with 2 optical somatic cell counters in routine use. On each of 3 days, 12 subsamples were prepared for each of 5 cell count levels from AM milk with half kept fresh and half preserved with 0.05% potassium dichromate. Subsamples were refrigerated and read 30+ h post-collection. Duplicate sets were read in random order on each machine daily (CV 0.77%). Two sets of slides read by 2 technicians each (strip reticle on 2 smears/slide) gave geometric mean direct microscopic somatic cell count (DMSCC) levels of 296, 526, 772, 930, and 1438 th/mL. Within-technician CV values (from day-level means) ranged from 1.68 to 2.28%. Geometric mean cells in th/mL on the new machine were significantly higher than those on the other two (674 vs 621) and were closer to the DMSCC (694). On the new machine, cell counts were 8.5% greater than on the original machines, were only 2.9% lower than the DMSCC, and showed no significant evidence of bias. Preserved samples averaged slightly greater than fresh (5.3%) but only on the original machines. Carryover by covariance analysis was insignificant. Except for cell levels, high machine precision (error CV value of 1.18%) gave differences with statistical but not practical significance, even for regulatory laboratories."
1234933,Peake et al. 1984,The effect of instrument variables on calculation factors for standardisation of colorimetric analyses,"A number of colorimetric methods, particularly enzyme activity assays, are usually standardised using calculation factors based on the molar absorptivity of a principle reactant or product. Such methods are subject to long-term variation. The relationship between long-term variation in results and instrument variables affecting calculation factors has not been quantitated. In this study, we have shown that, on a centrifugal analyser having a within-run coefficient of variation of less than 1%, instrument variables affecting calculation factor alone could result in changes in results of up to 8.5% over 75 days. We therefore advocate daily use of a solution of potassium dichromate to monitor instrument variables that can independently affect calculation factors and within-run imprecision. This procedure is useful for maintaining long-term performance and for differentiating problems of instrumental or chemical origin.","The effect of instrument variables on calculation factors for standardisation of colorimetric analyses Abs: A number of colorimetric methods, particularly enzyme activity assays, are usually standardised using calculation factors based on the molar absorptivity of a principle reactant or product. Such methods are subject to long-term variation. The relationship between long-term variation in results and instrument variables affecting calculation factors has not been quantitated. In this study, we have shown that, on a centrifugal analyser having a within-run coefficient of variation of less than 1%, instrument variables affecting calculation factor alone could result in changes in results of up to 8.5% over 75 days. We therefore advocate daily use of a solution of potassium dichromate to monitor instrument variables that can independently affect calculation factors and within-run imprecision. This procedure is useful for maintaining long-term performance and for differentiating problems of instrumental or chemical origin."
1234930,Christensen et al. 1984,Flare-up reactions and desensitization from oral dosing in chromate-sensitive guinea pigs,"Flare-up reactions were induced in potassium dichromate hypersensitive guinea pigs by a single oral dose of 55 mg/kg. This dose is systemically toxic and higher than the dose required to induce the same reactions in humans. A total oral dose of potassium dichromate of 90-115 mg/kg induced immunological unresponsiveness for at least 6 weeks. With limitations, the guinea pig model may be helpful in screening the hyposensitization capacity of different haptens dosed orally.","Flare-up reactions and desensitization from oral dosing in chromate-sensitive guinea pigs Abs: Flare-up reactions were induced in potassium dichromate hypersensitive guinea pigs by a single oral dose of 55 mg/kg. This dose is systemically toxic and higher than the dose required to induce the same reactions in humans. A total oral dose of potassium dichromate of 90-115 mg/kg induced immunological unresponsiveness for at least 6 weeks. With limitations, the guinea pig model may be helpful in screening the hyposensitization capacity of different haptens dosed orally."
1234929,Dey and  Hoffpauir 1984,Ultrastructural immunocytochemical localization of 5-hydroxytryptamine in gastric enterochromaffin cells,"Enterochromaffin (EC) cells in the gastrointestinal tract are known to contain 5-hydroxytryptamine (5HT). The probable ultrastructural localization of 5HT in the dense core vesicles ( DCVs ) of EC cells is based on the use of histochemical techniques, such as argentaffinity and the potassium dichromate reaction. In the present paper we describe an immunocytochemical method for specifically localizing 5HT in EC cells by electron microscopy. Pieces of mucosa from the pyloric region of the rabbit stomach were prepared for electron microscopy by fixation in 0.5% glutaraldehyde-picric acid-formaldehyde without osmication , and then embedded in LX-112. Thick sections (1 micron) were mounted on glass slides and processed for the fluorescence immunocytochemical localization of 5HT. Thin sections (60-90 nm) were mounted on formvar-coated slot grids and processed for the ultrastructural immunocytochemical localization of 5HT. Both the thick and thin sections were processed by an identical procedure, beginning with a 30-min incubation in anti-5HT antiserum diluted 1:1400, followed by an IgG-FITC-gold-labeled second antibody. Fluorescent EC cells were consistently observed in the thick sections of gastric mucosa. By carefully trimming and sectioning the adjacent block face, the identical EC cell could be identified by electron microscopy. A quantitative analysis revealed the number of gold particles in EC cells to be significantly greater over the cores of DCVs than over the non-core cytoplasm or over the nucleus. Absorption of the primary antiserum with 5HT abolished all labeling, while absorption with a 5HT precursor, 5-hydroxytryptophan, did not significantly reduce core labeling. Non-EC epithelial cells were not labeled. These results demonstrate that immunoreactive 5HT in EC cells is stored in the cores of DCVs .","Ultrastructural immunocytochemical localization of 5-hydroxytryptamine in gastric enterochromaffin cells Abs: Enterochromaffin (EC) cells in the gastrointestinal tract are known to contain 5-hydroxytryptamine (5HT). The probable ultrastructural localization of 5HT in the dense core vesicles ( DCVs ) of EC cells is based on the use of histochemical techniques, such as argentaffinity and the potassium dichromate reaction. In the present paper we describe an immunocytochemical method for specifically localizing 5HT in EC cells by electron microscopy. Pieces of mucosa from the pyloric region of the rabbit stomach were prepared for electron microscopy by fixation in 0.5% glutaraldehyde-picric acid-formaldehyde without osmication , and then embedded in LX-112. Thick sections (1 micron) were mounted on glass slides and processed for the fluorescence immunocytochemical localization of 5HT. Thin sections (60-90 nm) were mounted on formvar-coated slot grids and processed for the ultrastructural immunocytochemical localization of 5HT. Both the thick and thin sections were processed by an identical procedure, beginning with a 30-min incubation in anti-5HT antiserum diluted 1:1400, followed by an IgG-FITC-gold-labeled second antibody. Fluorescent EC cells were consistently observed in the thick sections of gastric mucosa. By carefully trimming and sectioning the adjacent block face, the identical EC cell could be identified by electron microscopy. A quantitative analysis revealed the number of gold particles in EC cells to be significantly greater over the cores of DCVs than over the non-core cytoplasm or over the nucleus. Absorption of the primary antiserum with 5HT abolished all labeling, while absorption with a 5HT precursor, 5-hydroxytryptophan, did not significantly reduce core labeling. Non-EC epithelial cells were not labeled. These results demonstrate that immunoreactive 5HT in EC cells is stored in the cores of DCVs ."
1234928,Siegel et al. 1984,Beneficial effect of thyroxin on recovery from toxic acute renal failure,"To determine the effect of thyroxin (T4) on the recovery from toxic acute renal failure, rats were injected, subcutaneously, with K-dichromate (15 mg/kg) and at the peak of the renal injury, each animal was given either T4 (4 micrograms/100 g body weight, i.p.) or normal saline (NS). The T4-treated rats had significantly better CIn (669 +/- 35 microliter/min/100 g body weight), improved FENa (0.49 +/- 0.05%) and increased UOsm (835 +/- 50 mOsm/kg) as compared to animals given only NS (CIn 422 +/- 27; FENa 1.02 +/- 0.12; and UOsm 613 +/- 23). A similar dose of T4 given to non-injured control rats had no effect on renal function. The beneficial effect of T4 on dichromate injected rats was sustained and lead to more prompt recovery of glomerular function. To eliminate any hemodynamic effects of T4, an isolated perfused kidney preparation was utilized, and kidneys from dichromate injected rats treated with T4 had significantly better CIn, urine flow and FENa compared to rats given NS. Cellular morphology was better preserved in T4-treated animals. These data indicate that treatment with T4 results in enhanced recovery from an acute toxic renal insult and that this beneficial effect is unlikely to be related to nonspecific systemic effects of the hormone.","Beneficial effect of thyroxin on recovery from toxic acute renal failure Abs: To determine the effect of thyroxin (T4) on the recovery from toxic acute renal failure, rats were injected, subcutaneously, with K-dichromate (15 mg/kg) and at the peak of the renal injury, each animal was given either T4 (4 micrograms/100 g body weight, i.p.) or normal saline (NS). The T4-treated rats had significantly better CIn (669 +/- 35 microliter/min/100 g body weight), improved FENa (0.49 +/- 0.05%) and increased UOsm (835 +/- 50 mOsm/kg) as compared to animals given only NS (CIn 422 +/- 27; FENa 1.02 +/- 0.12; and UOsm 613 +/- 23). A similar dose of T4 given to non-injured control rats had no effect on renal function. The beneficial effect of T4 on dichromate injected rats was sustained and lead to more prompt recovery of glomerular function. To eliminate any hemodynamic effects of T4, an isolated perfused kidney preparation was utilized, and kidneys from dichromate injected rats treated with T4 had significantly better CIn, urine flow and FENa compared to rats given NS. Cellular morphology was better preserved in T4-treated animals. These data indicate that treatment with T4 results in enhanced recovery from an acute toxic renal insult and that this beneficial effect is unlikely to be related to nonspecific systemic effects of the hormone."
1234927,Lofthus et al. 1984,"Metabolism of testosterone to 17 beta-hydroxy-5 alpha-androstane-3-one and 5 alpha-androstane-3 alpha, 17 beta-diol in alveolar macrophages from rat lung","5 alpha-Reduction of testosterone was observed in lung cells obtained by bronchoalveolar lavage (greater than 95% macrophages) from the rats. This activity was inhibited by progesterone and corticosterone. Production of 17 beta-hydroxy-5 alpha-androstane-3-one and 5 alpha-androstane-3 alpha, 17 beta-diol from testosterone was higher in rat pulmonary alveolar macrophages than by the 800 g supernatant fraction of whole lung homogenate from the same animals. Alveolar macrophages from rats treated with the 5 alpha-reductase inhibitor 17 beta-N,N-diethylcarbamoyl-4-aza-4-methyl-5 alpha-androstane-3-one (5 mg/100 g b.w., s.c.) showed decreased metabolism of testosterone to 17 beta-hydroxy-5 alpha-androstane-3-one and 5 alpha-androstane-3 alpha, 17 beta-diol 4 h after treatment. This metabolism was also decreased in alveolar macrophages from rats exposed to potassium dichromate by intratracheal instillation. When bovine alveolar macrophages were incubated with potassium dichromate, 5 alpha-reduction of testosterone decreased significantly. The function of steroid 5 alpha-reduction in alveolar macrophages is currently not known.","Metabolism of testosterone to 17 beta-hydroxy-5 alpha-androstane-3-one and 5 alpha-androstane-3 alpha, 17 beta-diol in alveolar macrophages from rat lung Abs: 5 alpha-Reduction of testosterone was observed in lung cells obtained by bronchoalveolar lavage (greater than 95% macrophages) from the rats. This activity was inhibited by progesterone and corticosterone. Production of 17 beta-hydroxy-5 alpha-androstane-3-one and 5 alpha-androstane-3 alpha, 17 beta-diol from testosterone was higher in rat pulmonary alveolar macrophages than by the 800 g supernatant fraction of whole lung homogenate from the same animals. Alveolar macrophages from rats treated with the 5 alpha-reductase inhibitor 17 beta-N,N-diethylcarbamoyl-4-aza-4-methyl-5 alpha-androstane-3-one (5 mg/100 g b.w., s.c.) showed decreased metabolism of testosterone to 17 beta-hydroxy-5 alpha-androstane-3-one and 5 alpha-androstane-3 alpha, 17 beta-diol 4 h after treatment. This metabolism was also decreased in alveolar macrophages from rats exposed to potassium dichromate by intratracheal instillation. When bovine alveolar macrophages were incubated with potassium dichromate, 5 alpha-reduction of testosterone decreased significantly. The function of steroid 5 alpha-reduction in alveolar macrophages is currently not known."
1234926,Barr et al. 1984,Levels of arachidonic acid and its metabolites in the skin in human allergic and irritant contact dermatitis,"Increased concentrations of arachidonic acid and prostaglandin E2, but not 12-hydroxy-eicosatetraenoic acid, were found in the skin in human contact dermatitis due to nickel and chromate allergens. Significant levels of neutrophil chemokinetic activity, with similar properties to leukotriene B4, were found in a high proportion of exudates from inflamed skin treated with allergen but not in exudates from untreated skin. Neither arachidonic acid nor its metabolites were increased in primary irritant dermatitis due to benzylalkonium chloride.","Levels of arachidonic acid and its metabolites in the skin in human allergic and irritant contact dermatitis Abs: Increased concentrations of arachidonic acid and prostaglandin E2, but not 12-hydroxy-eicosatetraenoic acid, were found in the skin in human contact dermatitis due to nickel and chromate allergens. Significant levels of neutrophil chemokinetic activity, with similar properties to leukotriene B4, were found in a high proportion of exudates from inflamed skin treated with allergen but not in exudates from untreated skin. Neither arachidonic acid nor its metabolites were increased in primary irritant dermatitis due to benzylalkonium chloride."
1234925,Berglind and  Dave 1984,"Acute toxicity of chromate, DDT, PCP, TPBS, and zinc to Daphnia magna cultured in hard and soft water",,"Acute toxicity of chromate, DDT, PCP, TPBS, and zinc to Daphnia magna cultured in hard and soft water Abs: "
1234923,Beernaert et al. 1984,Accidental environmental pollution of a residential quarter of Kortrijk by a chromic trioxide aerosol,"The extent of environmental pollution was determined following an accidental chromium-trioxide (1333820) leak from a Belgian chrome plating facility. The leak occurred during a weekend and was discovered on Monday morning, at which time the facility was shut down. Three days after the shutdown, plants, vegetables, and soil were sampled in gardens near the facility and analyzed for chromium(VI) (18540299). Outside a zone of brown vegetation, plants contained 0 to 8 milligrams (mg) chromium per kilogram (kg). Inside the zone, soil contained 44 to 59mg/kg chromium, while most plant and vegetable samples contained 121 to 931mg/kg. However, one sample of rhubarb stems contained only 2.6mg/kg. The authors conclude that the zone of brown vegetation indicated the area receiving virtually all the chromium(VI) contamination. A safe daily human intake of 0.17mg chromium(VI), suggests that the vegetables sampled in the contaminated zone are not safe for human consumption.","Accidental environmental pollution of a residential quarter of Kortrijk by a chromic trioxide aerosol Abs: The extent of environmental pollution was determined following an accidental chromium-trioxide (1333820) leak from a Belgian chrome plating facility. The leak occurred during a weekend and was discovered on Monday morning, at which time the facility was shut down. Three days after the shutdown, plants, vegetables, and soil were sampled in gardens near the facility and analyzed for chromium(VI) (18540299). Outside a zone of brown vegetation, plants contained 0 to 8 milligrams (mg) chromium per kilogram (kg). Inside the zone, soil contained 44 to 59mg/kg chromium, while most plant and vegetable samples contained 121 to 931mg/kg. However, one sample of rhubarb stems contained only 2.6mg/kg. The authors conclude that the zone of brown vegetation indicated the area receiving virtually all the chromium(VI) contamination. A safe daily human intake of 0.17mg chromium(VI), suggests that the vegetables sampled in the contaminated zone are not safe for human consumption."
1234922,Eaton et al. 1984,"Biological availability of lead in a paint aerosol. 2. Absorption, distribution and excretion of intratracheally instilled lead paint particles in the rat","Four groups of rats received by intratracheal instillation (1) a lead chromate paint particulate suspension, (2) lead tetraoxide suspension, (3) lead acetate solution, or (4) saline. Lead-dosed animals received an equivalent dose of 1 mg lead/kg body weight. Distribution of lead was monitored through assays of urine, feces, and tissues (lung, bone, muscle kidney, liver) obtained at post-mortem 5 weeks after exposure. Delta-aminolevulinic acid dehydratase (ALA-D) activity was measured to determine the effect of lead on heme biosynthesis. The vast majority of the dosed lead in the paint matrix remained in the lung. In contrast, in the lead acetate-dosed animals, little remained in the lung, but significant elevations were found in bone and kidney. Blood ADA-D was significantly depressed in the lead acetate-treated animals, but was not significantly different from control animals in the animals dosed with lead paint or lead tetraoxide. These findings suggest that lead chromate in an alkyd resin paint matrix is poorly absorbed from the lung compared with lead acetate and lead tetraoxide.","Biological availability of lead in a paint aerosol. 2. Absorption, distribution and excretion of intratracheally instilled lead paint particles in the rat Abs: Four groups of rats received by intratracheal instillation (1) a lead chromate paint particulate suspension, (2) lead tetraoxide suspension, (3) lead acetate solution, or (4) saline. Lead-dosed animals received an equivalent dose of 1 mg lead/kg body weight. Distribution of lead was monitored through assays of urine, feces, and tissues (lung, bone, muscle kidney, liver) obtained at post-mortem 5 weeks after exposure. Delta-aminolevulinic acid dehydratase (ALA-D) activity was measured to determine the effect of lead on heme biosynthesis. The vast majority of the dosed lead in the paint matrix remained in the lung. In contrast, in the lead acetate-dosed animals, little remained in the lung, but significant elevations were found in bone and kidney. Blood ADA-D was significantly depressed in the lead acetate-treated animals, but was not significantly different from control animals in the animals dosed with lead paint or lead tetraoxide. These findings suggest that lead chromate in an alkyd resin paint matrix is poorly absorbed from the lung compared with lead acetate and lead tetraoxide."
1234919,Weston and  Weston 1984,Allergic contact dermatitis in children,"Allergic contact dermatitis accounts for up to 20% of all dermatitis in childhood. The major sources of contact allergy in childhood are metals, shoes, preservatives, and plants. There is considerable variability from region to region and country to country in the prevalence and causes of contact dermatitis in childhood. We suggest that patch testing be done more frequently in evaluating dermatitis in children. Topical or systemic glucocorticosteroids and allergen avoidance are the mainstays of therapy in childhood.","Allergic contact dermatitis in children Abs: Allergic contact dermatitis accounts for up to 20% of all dermatitis in childhood. The major sources of contact allergy in childhood are metals, shoes, preservatives, and plants. There is considerable variability from region to region and country to country in the prevalence and causes of contact dermatitis in childhood. We suggest that patch testing be done more frequently in evaluating dermatitis in children. Topical or systemic glucocorticosteroids and allergen avoidance are the mainstays of therapy in childhood."
1234918,Siegfried and  Nesnow 1984,Cytotoxicity of chemical carcinogens towards human bronchial epithelial cells evaluated in a clonal assay,"Survival of human bronchial epithelial cells after administration of four chemical carcinogens was measured in a clonal assay. Human bronchial epithelial cells were obtained from outgrowths of explanted tissue pieces. Serum-free medium was used for both explant culture and clonal growth. The clonal assay could be performed on three substrata: plastic dishes alone, protein-coated dishes, and inactivated Swiss 3T3 cells. Several other cell lines supported clonal growth of the human cells. Fetal bovine serum was inhibitory to colony formation on plastic and protein-coated dishes, but had no effect on the growth of bronchial cells on 3T3 feeder cells. Little variation among individuals in cytotoxicity of N-methyl-N'-nitro-N-nitrosoguanidine (MNNG) and K2CrO4, a possible human lung carcinogen, was observed, but in the case of benzo[a]pyrene (BP) and 7,12-dimethyl-benz[a]anthracene (DMBA), large variations in survival were found between cultures derived from different individuals.","Cytotoxicity of chemical carcinogens towards human bronchial epithelial cells evaluated in a clonal assay Abs: Survival of human bronchial epithelial cells after administration of four chemical carcinogens was measured in a clonal assay. Human bronchial epithelial cells were obtained from outgrowths of explanted tissue pieces. Serum-free medium was used for both explant culture and clonal growth. The clonal assay could be performed on three substrata: plastic dishes alone, protein-coated dishes, and inactivated Swiss 3T3 cells. Several other cell lines supported clonal growth of the human cells. Fetal bovine serum was inhibitory to colony formation on plastic and protein-coated dishes, but had no effect on the growth of bronchial cells on 3T3 feeder cells. Little variation among individuals in cytotoxicity of N-methyl-N'-nitro-N-nitrosoguanidine (MNNG) and K2CrO4, a possible human lung carcinogen, was observed, but in the case of benzo[a]pyrene (BP) and 7,12-dimethyl-benz[a]anthracene (DMBA), large variations in survival were found between cultures derived from different individuals."
1234917,Clochesy 1984,Chromium ingestion: a case report,,Chromium ingestion: a case report Abs: 
1234916,Baker et al. 1984,Chromium(VI) and apparent phenotypic reversion in Salmonella TA100,"After treatment with potassium chromate at concentrations causing ultramicroscopic cellular lesions, a significant proportion (up to 75%) of TA100 colonies fail to replicate on fresh minimal plates containing biotin. This suggests that chromium(VI) may not always induce his- reversion to his+ in Salmonella TA100. The terms 'false' or phenotypic reversion have been used to distinguish such instances from 'true' or genotypic reversion, where progeny his+ cells readily grow on biotin replica plates. Results of the present study indicate that the majority of chromate-exposed colonies, initially scored as his-, are identifiable as his+ after 24 h culture on nutrient agar. Moreover, chromate exerts a cytostatic effect on TA100 since early colony development is suppressed at high chromate concentrations. A gradual chemical reduction of chromium(VI) ions by normal media compounds is probably responsible for the re-emergence of colony growth during prolonged incubation of test plates. Thus, temporary growth inhibition at high chromate concentration appears to be responsible for most of the non-replicating colonies detected in mutagenicity assays of chromium(VI).","Chromium(VI) and apparent phenotypic reversion in Salmonella TA100 Abs: After treatment with potassium chromate at concentrations causing ultramicroscopic cellular lesions, a significant proportion (up to 75%) of TA100 colonies fail to replicate on fresh minimal plates containing biotin. This suggests that chromium(VI) may not always induce his- reversion to his+ in Salmonella TA100. The terms 'false' or phenotypic reversion have been used to distinguish such instances from 'true' or genotypic reversion, where progeny his+ cells readily grow on biotin replica plates. Results of the present study indicate that the majority of chromate-exposed colonies, initially scored as his-, are identifiable as his+ after 24 h culture on nutrient agar. Moreover, chromate exerts a cytostatic effect on TA100 since early colony development is suppressed at high chromate concentrations. A gradual chemical reduction of chromium(VI) ions by normal media compounds is probably responsible for the re-emergence of colony growth during prolonged incubation of test plates. Thus, temporary growth inhibition at high chromate concentration appears to be responsible for most of the non-replicating colonies detected in mutagenicity assays of chromium(VI)."
1234915,Yawets et al. 1984,Biochemical and histological anomalies in the rat hepatic tissue following administration of bichromate and nickel in ionized form,"Administration of bichromate ions at a dose of 60 mg/kg body wt to female rats, reduced dramatically both hepatic microsomal cytochrome P-450 content and the monooxygenase activities assayed, namely: N-demethylation of aminopyrine and O-demethylation of p-nitroanisole. At the same dose the bichromate ion treatment caused a substantial decrease in cytochrome b5 content, but there was no significant reduction in NADPH-cytochrome c reductase activity. Administration of phenobarbital to bichromate ion pretreated rats did not induce a significant increase in cytochrome P-450 content nor in aminopyrine N-demethylase activity. Administration of nickel ions at a dose of 60 mg/kg body wt to female rats did not reduce to a significant level the content or the activity of any of the hepatic microsomal enzymes mentioned above, but did interfere in the de novo synthesis of cytochrome P-450 following phenobarbital treatment. The concentrations of nickel residues in the hepatic tissue of treated rats were only 5.8 times higher compared to the control rats, while those of chromium were 42 times higher than in control rats. Histological changes associated with the increase of bichromate concentration in treated rats were the formation of necrotic areas in the hepatic tissue and partial disintegration of the glomeruli and tubules in the kidney.","Biochemical and histological anomalies in the rat hepatic tissue following administration of bichromate and nickel in ionized form Abs: Administration of bichromate ions at a dose of 60 mg/kg body wt to female rats, reduced dramatically both hepatic microsomal cytochrome P-450 content and the monooxygenase activities assayed, namely: N-demethylation of aminopyrine and O-demethylation of p-nitroanisole. At the same dose the bichromate ion treatment caused a substantial decrease in cytochrome b5 content, but there was no significant reduction in NADPH-cytochrome c reductase activity. Administration of phenobarbital to bichromate ion pretreated rats did not induce a significant increase in cytochrome P-450 content nor in aminopyrine N-demethylase activity. Administration of nickel ions at a dose of 60 mg/kg body wt to female rats did not reduce to a significant level the content or the activity of any of the hepatic microsomal enzymes mentioned above, but did interfere in the de novo synthesis of cytochrome P-450 following phenobarbital treatment. The concentrations of nickel residues in the hepatic tissue of treated rats were only 5.8 times higher compared to the control rats, while those of chromium were 42 times higher than in control rats. Histological changes associated with the increase of bichromate concentration in treated rats were the formation of necrotic areas in the hepatic tissue and partial disintegration of the glomeruli and tubules in the kidney."
1234914,Baggett and  Berndt 1984,"Interaction of potassium dichromate with the nephrotoxins, mercuric chloride and citrinin","Potassium dichromate enhanced the effects of mercuric chloride or citrinin on renal slice transport of the organic ions p-aminohippurate (PAH) and tetraethylammonium (TEA) under certain experimental conditions. At the doses employed and times studied no effects, or only minimal effects, were observed on renal slice transport when the toxins were tested individually. Potassium dichromate (10 mg/kg) administered subcutaneously (s.c.) in combination with mercuric chloride (4 mg/kg, s.c.) or citrinin 35 or 55 mg/kg administered intraperitoneally (i.p.), resulted in a marked depression of organic ion transport. Similarly, the addition of potassium dichromate to fresh renal cortex slices in combination with mercuric chloride, enhanced the mercuric chloride-induced reduction of transport. No other interactions were observed under in vitro conditions.","Interaction of potassium dichromate with the nephrotoxins, mercuric chloride and citrinin Abs: Potassium dichromate enhanced the effects of mercuric chloride or citrinin on renal slice transport of the organic ions p-aminohippurate (PAH) and tetraethylammonium (TEA) under certain experimental conditions. At the doses employed and times studied no effects, or only minimal effects, were observed on renal slice transport when the toxins were tested individually. Potassium dichromate (10 mg/kg) administered subcutaneously (s.c.) in combination with mercuric chloride (4 mg/kg, s.c.) or citrinin 35 or 55 mg/kg administered intraperitoneally (i.p.), resulted in a marked depression of organic ion transport. Similarly, the addition of potassium dichromate to fresh renal cortex slices in combination with mercuric chloride, enhanced the mercuric chloride-induced reduction of transport. No other interactions were observed under in vitro conditions."
1234913,Merritt et al. 1984,The binding of metal salts and corrosion products to cells and proteins in vitro,"The binding of metal ions from salts and from corrosion products of 316 LVM stainless steel and MP-35 to blood cells and serum proteins was studied in vitro. In the first series of experiments, metal salts were added to whole blood and then the blood separated into red cells, white cells, and serum. Nickel from nickel chloride or corrosion products of stainless steel bound in very small quantities to blood cells. Cobalt from cobalt chloride bound to both red cells and white cells. Chromium from chromic chloride (Cr3+) bound to cells in very small quantities whereas chromium from potassium dichromate (Cr6+) and corrosion products showed very high to binding to red cells and some binding to white cells. In a second series of experiments the blood was separated into its components and then the metal salts were added and the binding pattern was identical. In a third series of experiments serum which had interacted with the metal salts or corrosion products was separated into its components by isoelectric focusing on polyacrylamide gels. Almost all of the metal, whatever the source, was detected in the albumin region of the gels indicating strong binding to albumin. These studies on the cell and protein binding of the metals help to explain the dissemination of corrosion products from the site of the implant and subsequent systemic responses by some individuals.","The binding of metal salts and corrosion products to cells and proteins in vitro Abs: The binding of metal ions from salts and from corrosion products of 316 LVM stainless steel and MP-35 to blood cells and serum proteins was studied in vitro. In the first series of experiments, metal salts were added to whole blood and then the blood separated into red cells, white cells, and serum. Nickel from nickel chloride or corrosion products of stainless steel bound in very small quantities to blood cells. Cobalt from cobalt chloride bound to both red cells and white cells. Chromium from chromic chloride (Cr3+) bound to cells in very small quantities whereas chromium from potassium dichromate (Cr6+) and corrosion products showed very high to binding to red cells and some binding to white cells. In a second series of experiments the blood was separated into its components and then the metal salts were added and the binding pattern was identical. In a third series of experiments serum which had interacted with the metal salts or corrosion products was separated into its components by isoelectric focusing on polyacrylamide gels. Almost all of the metal, whatever the source, was detected in the albumin region of the gels indicating strong binding to albumin. These studies on the cell and protein binding of the metals help to explain the dissemination of corrosion products from the site of the implant and subsequent systemic responses by some individuals."
1234912,Baran 1984,Oxide compounds on Ni-Cr alloys,"Five Ni-Cr alloys were studied in order to identify the compounds formed on the alloy surface during oxidation under conditions similar to those encountered during dental laboratory procedures prior to application of porcelain. After the alloys were oxidized, the films covering the surfaces were removed with the aid of a Br-methanol solution. X-ray diffraction was used to analyze the compounds formed. Oxides of nearly all elements contained by the alloys were found after low-temperature (650 degrees C) oxidation, while NiO and particularly Cr2O3 were predominant after oxidation at high temperatures (1000 degrees C).","Oxide compounds on Ni-Cr alloys Abs: Five Ni-Cr alloys were studied in order to identify the compounds formed on the alloy surface during oxidation under conditions similar to those encountered during dental laboratory procedures prior to application of porcelain. After the alloys were oxidized, the films covering the surfaces were removed with the aid of a Br-methanol solution. X-ray diffraction was used to analyze the compounds formed. Oxides of nearly all elements contained by the alloys were found after low-temperature (650 degrees C) oxidation, while NiO and particularly Cr2O3 were predominant after oxidation at high temperatures (1000 degrees C)."
1234908,Gunnarsson et al. 1984,Structural studies on the O-glycosidically linked carbohydrate chains of glucoamylase G1 from Aspergillus niger,"Glucoamylase G1 from Aspergillus niger contains an unusual type of carbohydrate-protein linkage, involving mannose O-glycosidically linked to serine and threonine. The majority of the neutral oligosaccharides of glucoamylase G1 are located in a region of about 70 amino acid residues which carries about 35 oligosaccharide units [(1983) Carlsberg Res. Commun. 48, 517-527]. Structural analysis was performed on the O-linked carbohydrates of a tryptic fragment from glucoamylase G1 comprising the segment characterized by a high degree of glycosylation. The carbohydrate structures released by trifluoroacetolysis were elucidated using sugar analysis, methylation analysis, mass spectrometry, chromium trioxide oxidation, digestion with alpha-mannosidase and 1H-NMR spectroscopy. The following structures could be identified. (formula; see text)","Structural studies on the O-glycosidically linked carbohydrate chains of glucoamylase G1 from Aspergillus niger Abs: Glucoamylase G1 from Aspergillus niger contains an unusual type of carbohydrate-protein linkage, involving mannose O-glycosidically linked to serine and threonine. The majority of the neutral oligosaccharides of glucoamylase G1 are located in a region of about 70 amino acid residues which carries about 35 oligosaccharide units [(1983) Carlsberg Res. Commun. 48, 517-527]. Structural analysis was performed on the O-linked carbohydrates of a tryptic fragment from glucoamylase G1 comprising the segment characterized by a high degree of glycosylation. The carbohydrate structures released by trifluoroacetolysis were elucidated using sugar analysis, methylation analysis, mass spectrometry, chromium trioxide oxidation, digestion with alpha-mannosidase and 1H-NMR spectroscopy. The following structures could be identified. (formula; see text)"
1234905,Nishio and  Uyeki 1985,Inhibition of DNA synthesis by chromium compounds,"Cr(VI) irreversibly inhibited DNA synthesis in cultured mouse L cells to 50% of controls at 10 microM; 3.3 mM Cr(III) did not. At 0.3 mM, Cr(III) and Cr(VI) inhibited DNA synthesis in permeabilized L cells to 50% of control values. Cr(III) was a stronger inhibitor of DNA synthesis in the DNA-Escherichia coli DNA polymerase I system than was Cr(VI). The inhibitory effect of Cr(VI) depended on the ratio of Cr/DNA and Cr/enzyme; on the other hand, the increase in the concentration of DNA polymerase did not affect the inhibition of Cr(III), Cr(III), below the inhibitory concentration, produced an increase in the incorporation of [3H]dTMP into DNA; this was not observed with Cr(VI).","Inhibition of DNA synthesis by chromium compounds Abs: Cr(VI) irreversibly inhibited DNA synthesis in cultured mouse L cells to 50% of controls at 10 microM; 3.3 mM Cr(III) did not. At 0.3 mM, Cr(III) and Cr(VI) inhibited DNA synthesis in permeabilized L cells to 50% of control values. Cr(III) was a stronger inhibitor of DNA synthesis in the DNA-Escherichia coli DNA polymerase I system than was Cr(VI). The inhibitory effect of Cr(VI) depended on the ratio of Cr/DNA and Cr/enzyme; on the other hand, the increase in the concentration of DNA polymerase did not affect the inhibition of Cr(III), Cr(III), below the inhibitory concentration, produced an increase in the incorporation of [3H]dTMP into DNA; this was not observed with Cr(VI)."
1234904,Reinhardt et al. 1985,Cell detachment and growth of fibroblasts as parameters for cytotoxicity of inorganic metal salts in vitro,"Eight inorganic metal compounds (AlCl3, Al(OH)3 gel, Al(OH)3 salt, SnCl2, ZnSO4, K2Cr2O7, CdCl2, HgCl2) were tested for their cytotoxic effect on an established hamster fibroblast line (BHK-21/C13) in vitro using a cell detachment assay and two different growth assays, the cloning efficiency and the cell number after 2 days subconfluent culture as parameters. The test conditions for these assays were optimized, including incubation period, application of test substance, growth conditions and data analysis. Aluminum, zinc and tin compounds showed low cytotoxic effects when compared to potassium, cadmium and mercuric compounds. Potassium dichromate was highly toxic in both growth assays (0.0001-0.01 mM, with a clear dependency on the incubation time), whereas it proved to be only slightly toxic in the detachment assay (0.1-5 mM). Cadmium and mercuric chlorides were the most toxic compounds in the growth (0.00001-0.001 mM) and the cell detachment assays (0.01-0.1 mM). Variable incubation periods barely affected the cytotoxicity of mercuric chloride. Ranking of these cytotoxicity data was found to be identical to the ranking of LD50 values (oral, rat) as well as to the ranking according to threshold limit values for human workroom environment, and of human eye irritation data.","Cell detachment and growth of fibroblasts as parameters for cytotoxicity of inorganic metal salts in vitro Abs: Eight inorganic metal compounds (AlCl3, Al(OH)3 gel, Al(OH)3 salt, SnCl2, ZnSO4, K2Cr2O7, CdCl2, HgCl2) were tested for their cytotoxic effect on an established hamster fibroblast line (BHK-21/C13) in vitro using a cell detachment assay and two different growth assays, the cloning efficiency and the cell number after 2 days subconfluent culture as parameters. The test conditions for these assays were optimized, including incubation period, application of test substance, growth conditions and data analysis. Aluminum, zinc and tin compounds showed low cytotoxic effects when compared to potassium, cadmium and mercuric compounds. Potassium dichromate was highly toxic in both growth assays (0.0001-0.01 mM, with a clear dependency on the incubation time), whereas it proved to be only slightly toxic in the detachment assay (0.1-5 mM). Cadmium and mercuric chlorides were the most toxic compounds in the growth (0.00001-0.001 mM) and the cell detachment assays (0.01-0.1 mM). Variable incubation periods barely affected the cytotoxicity of mercuric chloride. Ranking of these cytotoxicity data was found to be identical to the ranking of LD50 values (oral, rat) as well as to the ranking according to threshold limit values for human workroom environment, and of human eye irritation data."
1234903,Lob 1985,[Respiratory allergy to cement],,[Respiratory allergy to cement] Abs: 
1234902,Nesnow et al. 1985,"Studies on the tumor initiating, tumor promoting, and tumor co-initiating properties of respiratory carcinogens","The sensitivity of the mouse skin assay in detecting the carcinogenicity of known respiratory carcinogens was evaluated, and the tumor promoting and tumor coinitiating properties of complex environmental mixtures were investigated. SENCAR-mice were administered single intraperitoneal injections of beryllium-sulfate (13510491), nickel-sulfate (7786814), or potassium-dichromate (7778509), or treated topically once with 4-4'-methylene-bis(2-chloroaniline) (101144), followed by topical 12-O-tetradecanoylphorbol-13-acetate (16561298) (TPA) twice weekly for 26 weeks. No treatment resulted in significant numbers of mouse skin papillomas. In the tumor promotion studies, SENCAR-mice were topically treated once with 50 micrograms benzo(a)pyrene (50328) (BP) and then weekly with an extract of coke oven emissions or roofing tar emissions. The coke oven sample was approximately four times more active as a tumor promoter than the roofing tar sample. When treated weekly with the coke oven extract alone, mice were found to be more susceptible to carcinoma formation than the mice treated with BP followed by coke oven extract. Weekly treatments with roofing tar extract resulted in fewer papillomas than treatment with BP followed by roofing tar extract. Tumor coinitiation was studied in SENCAR-mice simultaneously treated with 50 micrograms BP and cigarette smoke condensate, roofing tar extract, or extract from diesel emissions, followed by twice weekly treatments with TPA for up to 30 weeks. Cigarette smoke condensate and roofing tar extract induced synergistic effects with BP. Both agents also had slight tumorigenic effects alone. Diesel extract induced significant tumor initiation by itself, but had no demonstrable effect when administered with BP as a coinitiator. The authors conclude that the mouse skin assay is not a sensitive test for evaluating the carcinogenicity of metal salts.","Studies on the tumor initiating, tumor promoting, and tumor co-initiating properties of respiratory carcinogens Abs: The sensitivity of the mouse skin assay in detecting the carcinogenicity of known respiratory carcinogens was evaluated, and the tumor promoting and tumor coinitiating properties of complex environmental mixtures were investigated. SENCAR-mice were administered single intraperitoneal injections of beryllium-sulfate (13510491), nickel-sulfate (7786814), or potassium-dichromate (7778509), or treated topically once with 4-4'-methylene-bis(2-chloroaniline) (101144), followed by topical 12-O-tetradecanoylphorbol-13-acetate (16561298) (TPA) twice weekly for 26 weeks. No treatment resulted in significant numbers of mouse skin papillomas. In the tumor promotion studies, SENCAR-mice were topically treated once with 50 micrograms benzo(a)pyrene (50328) (BP) and then weekly with an extract of coke oven emissions or roofing tar emissions. The coke oven sample was approximately four times more active as a tumor promoter than the roofing tar sample. When treated weekly with the coke oven extract alone, mice were found to be more susceptible to carcinoma formation than the mice treated with BP followed by coke oven extract. Weekly treatments with roofing tar extract resulted in fewer papillomas than treatment with BP followed by roofing tar extract. Tumor coinitiation was studied in SENCAR-mice simultaneously treated with 50 micrograms BP and cigarette smoke condensate, roofing tar extract, or extract from diesel emissions, followed by twice weekly treatments with TPA for up to 30 weeks. Cigarette smoke condensate and roofing tar extract induced synergistic effects with BP. Both agents also had slight tumorigenic effects alone. Diesel extract induced significant tumor initiation by itself, but had no demonstrable effect when administered with BP as a coinitiator. The authors conclude that the mouse skin assay is not a sensitive test for evaluating the carcinogenicity of metal salts."
1234901,Lisi and  Simonetti 1985,Contact sensitivity in children and adults with atopic dermatitis--a chronological study,"61 atopic dermatitis patients were subjected to a second patch testing 3-15 years (average 7.3 years) after the first contact sensitivity examination. The comparison between the results of the two studies revealed that 26.2% of patients had been sensitive to one or more haptens at the first patch testing and that 24.6% reacted positively at the second. 9 subjects (14.8%) still manifest contact sensitivity, while 6 (9.8%) reversed to positivity and 7 (11.5%) to negativity. The chemicals most frequently involved were nickel sulphate, potassium dichromate, benzoyl peroxide, diphenylguanidine. This study demonstrates that contact reactions are not linked to susceptibility to skin irritants in atopic dermatitis patients and that they tend to increase with time.","Contact sensitivity in children and adults with atopic dermatitis--a chronological study Abs: 61 atopic dermatitis patients were subjected to a second patch testing 3-15 years (average 7.3 years) after the first contact sensitivity examination. The comparison between the results of the two studies revealed that 26.2% of patients had been sensitive to one or more haptens at the first patch testing and that 24.6% reacted positively at the second. 9 subjects (14.8%) still manifest contact sensitivity, while 6 (9.8%) reversed to positivity and 7 (11.5%) to negativity. The chemicals most frequently involved were nickel sulphate, potassium dichromate, benzoyl peroxide, diphenylguanidine. This study demonstrates that contact reactions are not linked to susceptibility to skin irritants in atopic dermatitis patients and that they tend to increase with time."
1234900,Fischer and  Rystedt 1985,"False-positive, follicular and irritant patch test reactions to metal salts","853 hard metal workers were patch tested with nickel sulphate 5%, potassium dichromate 0.5% and cobalt chloride 1%, each in petrolatum. Non-allergic reactions appeared in 6.5% of the nickel tests, 13% of the chromium tests and 18.3% of the cobalt tests. Most of the individuals with positive, poral or pustular reactions were retested with serial dilutions of metal salts in pet. and in water. The accuracy of a positive initial nickel reaction was 83%, a chromium reaction 40% and a cobalt reaction 62%. The nonallergic reactions were partly reproducible and correlated with both the type of patch test material and with individual factors. Weak and moderately strong positive patch test reactions to metal salts may be irritant and should be checked with serial dilution tests or at least be retested. A reduction of the cobalt chloride concentration from 1% to 0.5% in the standard test material is discussed.","False-positive, follicular and irritant patch test reactions to metal salts Abs: 853 hard metal workers were patch tested with nickel sulphate 5%, potassium dichromate 0.5% and cobalt chloride 1%, each in petrolatum. Non-allergic reactions appeared in 6.5% of the nickel tests, 13% of the chromium tests and 18.3% of the cobalt tests. Most of the individuals with positive, poral or pustular reactions were retested with serial dilutions of metal salts in pet. and in water. The accuracy of a positive initial nickel reaction was 83%, a chromium reaction 40% and a cobalt reaction 62%. The nonallergic reactions were partly reproducible and correlated with both the type of patch test material and with individual factors. Weak and moderately strong positive patch test reactions to metal salts may be irritant and should be checked with serial dilution tests or at least be retested. A reduction of the cobalt chloride concentration from 1% to 0.5% in the standard test material is discussed."
1234899,Mohr and  Emura 1985,The use of cell and organ culture from the respiratory tract for testing chemicals,"For the toxicity testing of compounds using tissue from the respiratory tract, three types of in vitro cell or tissue culture systems are being developed from foetal Syrian hamster respiratory organs on day 15 of gestation. The first system, early-passage cell cultures of a mixed population obtained from foetal lungs, has been used frequently for the study of in vitro cell transformation. The clonal culture technique using these cells permitted the semi-quantitative determination of the toxicity of poly- or heterocyclic hydrocarbons in terms of the reduction in the number of surviving colonies. The second system, an explant culture technique using foetal tracheae, demonstrated the induction, by polycyclic hydrocarbons, of alterations such as hyperplasia, epidermoid metaplasia or dysplasia of mucociliary epithelia. The third system uses the cells of a permanent clonal epithelial cell line established from the foetal lung. These cells differentiated into a mucus-producing cell type in a medium supplemented with vitamin A and hormone. In order to observe general aspects of toxicity in these cells, they were exposed first to model substances such as sulphuric acid and potassium dichromate. After 24 hr of post-exposure incubation, the activities of membrane-bound and cytosolic enzymes, the amount of sialic acid released into the medium and cell survival were measured. Based on the results obtained so far, the potential value of each system is discussed.","The use of cell and organ culture from the respiratory tract for testing chemicals Abs: For the toxicity testing of compounds using tissue from the respiratory tract, three types of in vitro cell or tissue culture systems are being developed from foetal Syrian hamster respiratory organs on day 15 of gestation. The first system, early-passage cell cultures of a mixed population obtained from foetal lungs, has been used frequently for the study of in vitro cell transformation. The clonal culture technique using these cells permitted the semi-quantitative determination of the toxicity of poly- or heterocyclic hydrocarbons in terms of the reduction in the number of surviving colonies. The second system, an explant culture technique using foetal tracheae, demonstrated the induction, by polycyclic hydrocarbons, of alterations such as hyperplasia, epidermoid metaplasia or dysplasia of mucociliary epithelia. The third system uses the cells of a permanent clonal epithelial cell line established from the foetal lung. These cells differentiated into a mucus-producing cell type in a medium supplemented with vitamin A and hormone. In order to observe general aspects of toxicity in these cells, they were exposed first to model substances such as sulphuric acid and potassium dichromate. After 24 hr of post-exposure incubation, the activities of membrane-bound and cytosolic enzymes, the amount of sialic acid released into the medium and cell survival were measured. Based on the results obtained so far, the potential value of each system is discussed."
1234898,Pilone 1985,Determination of ethanol in wine by titrimetric and spectrophotometric dichromate methods: collaborative study,"A dichromate-spectrophotometric method for the determination of ethanol in wine was compared in a collaborative, matched pair study with the AOAC dichromate-titrimetric method, 11.008-11.011. Both methods require distillation of the sample into dichromate. The titrimetric method measures ethanol by titrating the excess dichromate with ferrous ammonium sulfate after conversion of ethanol to acetic acid; the spectrophotometric method directly measures the reduced dichromate formed after oxidation. In addition to comparing the 2 methods, the collaborative study also compared the use of 2 types of assemblies for obtaining the ethanol distillate: the Scott-type, which is used in 11.008-11.011, and the electric Kirk-type. Results of the collaborative study indicated that the repeatability and reproducibility of the official titrimetric method were generally far superior to those of the spectrophotometric method; therefore, adoption of the spectrophotometric method is not recommended. Comparison of titrimetric method results obtained using the 2 types of stills indicated that repeatability and reproducibility were somewhat better when Scott apparatus was used, but measurements using Kirk-type compared well in the range of ethanol concentrations found in table and fortified wines. The Kirk-type distillation apparatus has been adopted official first action as an alternative to Scott apparatus in the dichromate oxidation method for ethanol in wine, 11.008-11.011.","Determination of ethanol in wine by titrimetric and spectrophotometric dichromate methods: collaborative study Abs: A dichromate-spectrophotometric method for the determination of ethanol in wine was compared in a collaborative, matched pair study with the AOAC dichromate-titrimetric method, 11.008-11.011. Both methods require distillation of the sample into dichromate. The titrimetric method measures ethanol by titrating the excess dichromate with ferrous ammonium sulfate after conversion of ethanol to acetic acid; the spectrophotometric method directly measures the reduced dichromate formed after oxidation. In addition to comparing the 2 methods, the collaborative study also compared the use of 2 types of assemblies for obtaining the ethanol distillate: the Scott-type, which is used in 11.008-11.011, and the electric Kirk-type. Results of the collaborative study indicated that the repeatability and reproducibility of the official titrimetric method were generally far superior to those of the spectrophotometric method; therefore, adoption of the spectrophotometric method is not recommended. Comparison of titrimetric method results obtained using the 2 types of stills indicated that repeatability and reproducibility were somewhat better when Scott apparatus was used, but measurements using Kirk-type compared well in the range of ethanol concentrations found in table and fortified wines. The Kirk-type distillation apparatus has been adopted official first action as an alternative to Scott apparatus in the dichromate oxidation method for ethanol in wine, 11.008-11.011."
1234895,Watanabe et al. 1985,In vivo clastogenicity of lead chromate in mice,"Cytogenetical effects of lead chromate were evaluated in vivo. When 0.5, 1, 2 and 4 g/kg body weight of lead chromate suspensions in 0.5% gum arabic were administered i.p. to C57BL/6N male mice twice, the frequencies of micronucleated polychromatic erythrocytes in the femoral bone marrow were significantly (p less than 0.01) different from that in the vehicle control. Moreover, as the dose increased, the ratio of the polychromatic to normochromatic erythrocytes decreased in a dose-response fashion (p less than 0.05). Thus, it is concluded that lead chromate in vivo gives rise to chromosomal damage as well as disturbance in hematopoiesis.","In vivo clastogenicity of lead chromate in mice Abs: Cytogenetical effects of lead chromate were evaluated in vivo. When 0.5, 1, 2 and 4 g/kg body weight of lead chromate suspensions in 0.5% gum arabic were administered i.p. to C57BL/6N male mice twice, the frequencies of micronucleated polychromatic erythrocytes in the femoral bone marrow were significantly (p less than 0.01) different from that in the vehicle control. Moreover, as the dose increased, the ratio of the polychromatic to normochromatic erythrocytes decreased in a dose-response fashion (p less than 0.05). Thus, it is concluded that lead chromate in vivo gives rise to chromosomal damage as well as disturbance in hematopoiesis."
1234894,Tandon and  Srivastava 1985,Chelation in metal intoxication XVII: Antidotal efficacy of polyaminocarboxylic acids on acute chromate toxicity,"Some polyaminocarboxylic acids containing amino and carboxyl groups as metal binding sites in different structural arrangements were evaluated for their relative efficacy in protecting against acute chromate intoxication in mice. Nitrilotriacetic acid (NTA) and 1,2 cyclohexylenediamine tetraacetic acid (CDTA) were most effective in preventing mortality (50-70%) due to a lethal dose of potassium chromate at one-tenth of their respective LD50.","Chelation in metal intoxication XVII: Antidotal efficacy of polyaminocarboxylic acids on acute chromate toxicity Abs: Some polyaminocarboxylic acids containing amino and carboxyl groups as metal binding sites in different structural arrangements were evaluated for their relative efficacy in protecting against acute chromate intoxication in mice. Nitrilotriacetic acid (NTA) and 1,2 cyclohexylenediamine tetraacetic acid (CDTA) were most effective in preventing mortality (50-70%) due to a lethal dose of potassium chromate at one-tenth of their respective LD50."
1234893,Parks et al. 1985,GFAAS determination of ultratrace quantities of organotins in sea-water by using enhancement methods,"Tributyltin in sea-water is preconcentrated by extraction into toluene and determined by enhanced graphite-furnace atomic-absorption (GFAAS) at ultratrace concentrations (as low as 1.0 mug l .) equal to or lower than the toxic limits for aquatic organotins. Toluene is preferred to MIBK, chloroform or hexane as the solvent. Sea salts, in concentrations as low as 0.1%, critically interfere with GFAAS tin determinations, and must be removed by washing the extract with demineralized water. Signal enhancement effected by inserting L'vov platforms in the graphite furnace tubes or by adding ammonium dichromate to the analyte solution is nearly additive when both methods of enhancement are combined.","GFAAS determination of ultratrace quantities of organotins in sea-water by using enhancement methods Abs: Tributyltin in sea-water is preconcentrated by extraction into toluene and determined by enhanced graphite-furnace atomic-absorption (GFAAS) at ultratrace concentrations (as low as 1.0 mug l .) equal to or lower than the toxic limits for aquatic organotins. Toluene is preferred to MIBK, chloroform or hexane as the solvent. Sea salts, in concentrations as low as 0.1%, critically interfere with GFAAS tin determinations, and must be removed by washing the extract with demineralized water. Signal enhancement effected by inserting L'vov platforms in the graphite furnace tubes or by adding ammonium dichromate to the analyte solution is nearly additive when both methods of enhancement are combined."
1234892,Ferguson et al. 1985,Lymphocyte subsets and Langerhans cells in allergic and irritant patch test reactions: histometric studies,"This study has attempted to distinguish between allergic and irritant reactions to patch tests by semiquantitative histological methods. The extent of perivascular chronic inflammatory infiltrate at 72 h in irritant patch test reactions to sodium lauryl sulphate was shown to be small and very consistent, whereas in allergic reactions to nickel sulphate it was generally larger and more variable in size (p less than 0.02). The two major lymphocyte subsets (T4 and T8) were randomly intermixed in both types of reaction and formed the major component of both the perivascular and diffuse dermal infiltrate, without any evidence of selective migration. The T4:T8 ratios were similar in focal and diffuse infiltrates. The number of T6 dendritic (putative Langerhans) cells in the epidermis (per mm inner epidermal length) was usually greatly reduced in irritant reactions (5-16 mm-1, mean 10 mm-1) but remained within normal limits in allergic reactions (6-33 mm-1, mean 21 mm-1) (p less than 0.001). Comparable results were seen with other irritants (mercuric chloride and benzalkonium chloride) and other allergens (neomycin sulphate, ethylene diamine and potassium dichromate). In additional experiments, pairs of biopsies were taken from the reaction and from adjacent unaffected skin. The T6 cell density in the epidermis did not significantly differ between allergic reactions and control skin. By contrast, the irritant reactions had fewer T6 cells than the control skin (p less than 0.001).","Lymphocyte subsets and Langerhans cells in allergic and irritant patch test reactions: histometric studies Abs: This study has attempted to distinguish between allergic and irritant reactions to patch tests by semiquantitative histological methods. The extent of perivascular chronic inflammatory infiltrate at 72 h in irritant patch test reactions to sodium lauryl sulphate was shown to be small and very consistent, whereas in allergic reactions to nickel sulphate it was generally larger and more variable in size (p less than 0.02). The two major lymphocyte subsets (T4 and T8) were randomly intermixed in both types of reaction and formed the major component of both the perivascular and diffuse dermal infiltrate, without any evidence of selective migration. The T4:T8 ratios were similar in focal and diffuse infiltrates. The number of T6 dendritic (putative Langerhans) cells in the epidermis (per mm inner epidermal length) was usually greatly reduced in irritant reactions (5-16 mm-1, mean 10 mm-1) but remained within normal limits in allergic reactions (6-33 mm-1, mean 21 mm-1) (p less than 0.001). Comparable results were seen with other irritants (mercuric chloride and benzalkonium chloride) and other allergens (neomycin sulphate, ethylene diamine and potassium dichromate). In additional experiments, pairs of biopsies were taken from the reaction and from adjacent unaffected skin. The T6 cell density in the epidermis did not significantly differ between allergic reactions and control skin. By contrast, the irritant reactions had fewer T6 cells than the control skin (p less than 0.001)."
1234891,Nikunen and  Miettinen 1985,Daphnia magna as an indicator of the acute toxicity of waste waters,,Daphnia magna as an indicator of the acute toxicity of waste waters Abs: 
1234889,Krzywicka and  Krawczyk 1985,[Acute poisoning with potassium dichromate],,[Acute poisoning with potassium dichromate] Abs: 
1234888,De Flora et al. 1985,"Genotoxicity assay of oil dispersants in bacteria (mutation, differential lethality, SOS DNA-repair) and yeast (mitotic crossing-over)","5 oil dispersants and a sample of paraffin were devoid of mutagenic activity in the Ames reversion test, with and without S9 mix, using 7 his- S. typhimurium strains (TA1535, TA1537, TA1538, TA97, TA98, TA100, TA102). However, 3 dispersants produced direct DNA damage in E. coli WP2, which was not repairable in repair-deficient strains (WP2uvrA, CM871, TM1080), as shown by two different DNA-repair test procedures. The uvrA excision-repair system was in all cases the most important mechanism involved in repairing the DNA damage produced by oil dispersants, while the combination of uvrA with other genetic defects (polA, recA, lexA) decreased the efficiency of the system. The observed genotoxic effects were considerably lowered in the presence of S9 mix containing liver S9 fractions from Aroclor-treated rats. The sample of oil dispersant yielding the most pronounced DNA damage in repair-deficient E. coli failed to induce gene sfiA in E. coli (strain PQ37), using the SOS chromotest, or mitotic crossing-over in Saccharomyces cerevisiae (strain D5). The direct toxicity of the oil dispersant to both bacterial and yeast cells was markedly decreased in the presence of rat-liver preparations. These two short-term tests were effective in detecting the genotoxicity of both direct-acting compounds (such as 4-nitroquinoline N-oxide and methyl methanesulfonate) and procarcinogens (such as cyclophosphamide, 2-aminoanthracene and 2-aminofluorene). Moreover, the SOS chromotest was successfully applied to discriminate the activity of chromium compounds as related to their valence (i.e. Cr(VI) genotoxic and Cr(III) inactive). Combination of oil dispersants with Cr(VI) compounds did not affect the direct mutagenicity to S. typhimurium (TA102) of a soluble salt (sodium dichromate) nor did it result in any release of a water-soluble salt (lead chromate), as also confirmed by analytical methods. On the other hand, exposure to sunlight tended to decrease, to a slow rate, the direct genotoxicity of an oil dispersant in the bacterial DNA-repair test.","Genotoxicity assay of oil dispersants in bacteria (mutation, differential lethality, SOS DNA-repair) and yeast (mitotic crossing-over) Abs: 5 oil dispersants and a sample of paraffin were devoid of mutagenic activity in the Ames reversion test, with and without S9 mix, using 7 his- S. typhimurium strains (TA1535, TA1537, TA1538, TA97, TA98, TA100, TA102). However, 3 dispersants produced direct DNA damage in E. coli WP2, which was not repairable in repair-deficient strains (WP2uvrA, CM871, TM1080), as shown by two different DNA-repair test procedures. The uvrA excision-repair system was in all cases the most important mechanism involved in repairing the DNA damage produced by oil dispersants, while the combination of uvrA with other genetic defects (polA, recA, lexA) decreased the efficiency of the system. The observed genotoxic effects were considerably lowered in the presence of S9 mix containing liver S9 fractions from Aroclor-treated rats. The sample of oil dispersant yielding the most pronounced DNA damage in repair-deficient E. coli failed to induce gene sfiA in E. coli (strain PQ37), using the SOS chromotest, or mitotic crossing-over in Saccharomyces cerevisiae (strain D5). The direct toxicity of the oil dispersant to both bacterial and yeast cells was markedly decreased in the presence of rat-liver preparations. These two short-term tests were effective in detecting the genotoxicity of both direct-acting compounds (such as 4-nitroquinoline N-oxide and methyl methanesulfonate) and procarcinogens (such as cyclophosphamide, 2-aminoanthracene and 2-aminofluorene). Moreover, the SOS chromotest was successfully applied to discriminate the activity of chromium compounds as related to their valence (i.e. Cr(VI) genotoxic and Cr(III) inactive). Combination of oil dispersants with Cr(VI) compounds did not affect the direct mutagenicity to S. typhimurium (TA102) of a soluble salt (sodium dichromate) nor did it result in any release of a water-soluble salt (lead chromate), as also confirmed by analytical methods. On the other hand, exposure to sunlight tended to decrease, to a slow rate, the direct genotoxicity of an oil dispersant in the bacterial DNA-repair test."
1234887,Hansen and  Stern 1985,Welding fumes and chromium compounds in cell transformation assays,"Fumes generated from mild steel and stainless steel welding were collected on paper filters and tested in the BHK and SHE cell transformation assays. Fumes from the manual metal arc welding of stainless steel (MMA/SS) had a toxic and transforming effect attributable to their Cr(VI) content. The fumes from metal inert gas stainless steel (MIG/SS) welding also had a toxic effect but this was 2-3 times greater than that expected from their soluble Cr(VI) content based on the activity of soluble Cr(VI) from pure chromium compounds. When collected in an impinger, the fumes from MIG/SS were found to contain approximately 10 times the soluble Cr(VI) content of samples collected on filters. This additional Cr(VI), when collected in a water impinger, also exhibited a greater toxicity compared with that found for the additional Cr(VI) collected in an impinger filled with growth medium. This comparison implies the presence of a short-lived biologically active Cr(VI) species usually lost in conventional sampling techniques. It also implies that there is a detoxification step associated with the formation of Cr(VI) organic complexes. Relatively insoluble Cr(VI) compounds showed a higher toxic and transforming effect in the BHK assay than could be ascribed to the soluble Cr(VI) content of the medium, indicating the importance of phagocytosis as a pathway for the uptake of Cr(VI) and other toxic substances from particulates.","Welding fumes and chromium compounds in cell transformation assays Abs: Fumes generated from mild steel and stainless steel welding were collected on paper filters and tested in the BHK and SHE cell transformation assays. Fumes from the manual metal arc welding of stainless steel (MMA/SS) had a toxic and transforming effect attributable to their Cr(VI) content. The fumes from metal inert gas stainless steel (MIG/SS) welding also had a toxic effect but this was 2-3 times greater than that expected from their soluble Cr(VI) content based on the activity of soluble Cr(VI) from pure chromium compounds. When collected in an impinger, the fumes from MIG/SS were found to contain approximately 10 times the soluble Cr(VI) content of samples collected on filters. This additional Cr(VI), when collected in a water impinger, also exhibited a greater toxicity compared with that found for the additional Cr(VI) collected in an impinger filled with growth medium. This comparison implies the presence of a short-lived biologically active Cr(VI) species usually lost in conventional sampling techniques. It also implies that there is a detoxification step associated with the formation of Cr(VI) organic complexes. Relatively insoluble Cr(VI) compounds showed a higher toxic and transforming effect in the BHK assay than could be ascribed to the soluble Cr(VI) content of the medium, indicating the importance of phagocytosis as a pathway for the uptake of Cr(VI) and other toxic substances from particulates."
1234884,Sinclair and  Nurse 1985,Finger tip dermatitis,BIOSIS COPYRIGHT: BIOL ABS. RRM HUMAN MATCH HEAD CONTACT POTASSIUM DICHROMATE,Finger tip dermatitis Abs: BIOSIS COPYRIGHT: BIOL ABS. RRM HUMAN MATCH HEAD CONTACT POTASSIUM DICHROMATE
1234883,Baggett and  Berndt 1985,The effect of potassium dichromate and mercuric chloride on urinary excretion and organ and subcellular distribution of [203Hg]mercuric chloride in rats,"The mechanism by which subthreshold/non-effective doses or concentrations of potassium dichromate (K2Cr2O7) potentiate the effect of moderately effective dose/concentrations of mercuric chloride (HgCl2) on renal organic ion transport is not understood. To investigate this effect, the rate of excretion of mercury from the intact animal and the renal and hepatic accumulation and subcellular distribution of mercury within kidney cortex following pretreatment or in vitro exposure to K2Cr2O7 were undertaken. Coincidental administration of K2Cr2O7 had no significant effect in altering the rate of excretion of labeled mercury. Organ distribution showed time dependence; however, the presence of K2Cr2O7 did not increase renal mercury concentrations. In fact, significantly less mercury was found at 4 h in the kidneys of rats receiving both metal salts. Subcellular distribution of labeled mercury (203Hg) was also not significantly altered by the presence of K2Cr2O7, although the distribution patterns for in vitro exposure and pretreated tissues were different. These studies show that K2Cr2O7 does not produce alterations in urinary elimination, organ distribution or subcellular distribution of mercury.","The effect of potassium dichromate and mercuric chloride on urinary excretion and organ and subcellular distribution of [203Hg]mercuric chloride in rats Abs: The mechanism by which subthreshold/non-effective doses or concentrations of potassium dichromate (K2Cr2O7) potentiate the effect of moderately effective dose/concentrations of mercuric chloride (HgCl2) on renal organic ion transport is not understood. To investigate this effect, the rate of excretion of mercury from the intact animal and the renal and hepatic accumulation and subcellular distribution of mercury within kidney cortex following pretreatment or in vitro exposure to K2Cr2O7 were undertaken. Coincidental administration of K2Cr2O7 had no significant effect in altering the rate of excretion of labeled mercury. Organ distribution showed time dependence; however, the presence of K2Cr2O7 did not increase renal mercury concentrations. In fact, significantly less mercury was found at 4 h in the kidneys of rats receiving both metal salts. Subcellular distribution of labeled mercury (203Hg) was also not significantly altered by the presence of K2Cr2O7, although the distribution patterns for in vitro exposure and pretreated tissues were different. These studies show that K2Cr2O7 does not produce alterations in urinary elimination, organ distribution or subcellular distribution of mercury."
1234882,Jansson et al. 1985,Structural studies of the O-antigen polysaccharides of Klebsiella O5 and Escherichia coli O8,"The O-antigen polysaccharides of Klebsiella serotype O5 and Escherichia coli serotype O8 are serologically very similar or identical. The structures of these two polysaccharides have now been re-investigated. N.m.r. spectroscopy, chromium trioxide oxidation, hydrolysis with a specific phage enzyme, and f.a.b. mass spectrometry were the principal methods used. It is concluded that the O-antigen has the following structure, in which D-Man3Me is 3-O-methyl-D-mannose and n is approximately 10. (Formula: see text) Biosynthetic studies indicate that these antigens are synthesised by addition of D-mannopyranosyl groups to the &quot;non-reducing&quot; end of the mannan chain, and it seems possible that addition of a 3-O-methyl-D-mannopyranosyl group involves termination.","Structural studies of the O-antigen polysaccharides of Klebsiella O5 and Escherichia coli O8 Abs: The O-antigen polysaccharides of Klebsiella serotype O5 and Escherichia coli serotype O8 are serologically very similar or identical. The structures of these two polysaccharides have now been re-investigated. N.m.r. spectroscopy, chromium trioxide oxidation, hydrolysis with a specific phage enzyme, and f.a.b. mass spectrometry were the principal methods used. It is concluded that the O-antigen has the following structure, in which D-Man3Me is 3-O-methyl-D-mannose and n is approximately 10. (Formula: see text) Biosynthetic studies indicate that these antigens are synthesised by addition of D-mannopyranosyl groups to the &quot;non-reducing&quot; end of the mannan chain, and it seems possible that addition of a 3-O-methyl-D-mannopyranosyl group involves termination."
1234879,Cervantes-Vega et al. 1986,Resistance to metals by Pseudomonas aeruginosa clinical isolates,"The susceptibility of 326 clinical isolates of Pseudomonas aeruginosa to four metals was determined by agar dilution tests. Metal resistance was shown by 36% of the total isolates. The frequencies of resistance to individual ions were: mercuric, 31%; tellurite, 12%; arsenate, 10%; and chromate, 3%. The most frequent pattern was that of resistance to mercuric ions alone followed by mercury resistance associated with either tellurite, arsenate, or both. Resistance to more than one metal was found in 44% of metal-resistant isolates. The resistance to antibiotics was more frequent among metal-resistant isolates that in metal-sensitive isolates.","Resistance to metals by Pseudomonas aeruginosa clinical isolates Abs: The susceptibility of 326 clinical isolates of Pseudomonas aeruginosa to four metals was determined by agar dilution tests. Metal resistance was shown by 36% of the total isolates. The frequencies of resistance to individual ions were: mercuric, 31%; tellurite, 12%; arsenate, 10%; and chromate, 3%. The most frequent pattern was that of resistance to mercuric ions alone followed by mercury resistance associated with either tellurite, arsenate, or both. Resistance to more than one metal was found in 44% of metal-resistant isolates. The resistance to antibiotics was more frequent among metal-resistant isolates that in metal-sensitive isolates."
1234878,LaVelle 1986,Chromium (VI) comutagenesis: characterization of the interaction of K2CrO4 with azide,"In a previous report chromate potentiated the mutagenicity of sodium azide, apparently by affecting repair and/or replication of DNA. Further evidence in support of such a mechanism for chromate potentiation is reported here. Chromate does not react directly with azide or its major mutagenic metabolite, azidoalanine, eliminating such reactions as possible mechanisms for potentiation. Further, azide was unable to potentiate the mutagenicity of chromate in Salmonella typhimurium strain TA104, which is sensitive to chromate mutagenicity but not to azide. Thus, it appears that the potentiation is not due to an action of azide in modulating chromate mutagenicity. Finally, the interaction was not altered by deficiency in recA gene product in S typhimurium GW19, nor by enhancement of SOS repair in the pKM101 containing strain TA100. Thus, induction of recA-dependent functions seems to play no role in the comutagenic actions of chromate. The simplest explanation for potentiation seems to be that chromate is able either to limit error-free recovery from azide-induced DNA damage or to promote error-prone repair or error-prone processing at sites of lesions.","Chromium (VI) comutagenesis: characterization of the interaction of K2CrO4 with azide Abs: In a previous report chromate potentiated the mutagenicity of sodium azide, apparently by affecting repair and/or replication of DNA. Further evidence in support of such a mechanism for chromate potentiation is reported here. Chromate does not react directly with azide or its major mutagenic metabolite, azidoalanine, eliminating such reactions as possible mechanisms for potentiation. Further, azide was unable to potentiate the mutagenicity of chromate in Salmonella typhimurium strain TA104, which is sensitive to chromate mutagenicity but not to azide. Thus, it appears that the potentiation is not due to an action of azide in modulating chromate mutagenicity. Finally, the interaction was not altered by deficiency in recA gene product in S typhimurium GW19, nor by enhancement of SOS repair in the pKM101 containing strain TA100. Thus, induction of recA-dependent functions seems to play no role in the comutagenic actions of chromate. The simplest explanation for potentiation seems to be that chromate is able either to limit error-free recovery from azide-induced DNA damage or to promote error-prone repair or error-prone processing at sites of lesions."
1234877,Baggett and  Berndt 1986,Renal function in the rat after treatment with mercuric chloride plus potassium dichromate,"The treatment of rats with single subcutaneous (sc) doses of mercuric chloride (4 mg/kg) plus potassium dichromate (10 mg/kg) resulted in greater effects on water consumption, urine volume, body weight, and urinary electrolyte excretion than produced by mercuric chloride alone. The dose of potassium dichromate alone had no effects on renal function. Urine volume at 6 hr was increased twofold over mercuric chloride alone. Similarly, potassium excretion by these animals at 6 hr was significantly decreased compared to controls. These animals were oliguric by 24 hr after the injection. Urine osmolality of rats receiving the combination of the metals remained lower than controls throughout the 4-day experimental period. Measurement of renal arterial blood flow by electromagnetic flow probe after subcutaneous injection of saline, mercuric chloride (4 mg/kg), potassium dichromate (10 mg/kg), or the combination, produced no change over a 2.5-hr period, at 24 hr, and at 48 hr, and the glomerular filtration rate (GFR) of these rats was not affected over the same period of time.","Renal function in the rat after treatment with mercuric chloride plus potassium dichromate Abs: The treatment of rats with single subcutaneous (sc) doses of mercuric chloride (4 mg/kg) plus potassium dichromate (10 mg/kg) resulted in greater effects on water consumption, urine volume, body weight, and urinary electrolyte excretion than produced by mercuric chloride alone. The dose of potassium dichromate alone had no effects on renal function. Urine volume at 6 hr was increased twofold over mercuric chloride alone. Similarly, potassium excretion by these animals at 6 hr was significantly decreased compared to controls. These animals were oliguric by 24 hr after the injection. Urine osmolality of rats receiving the combination of the metals remained lower than controls throughout the 4-day experimental period. Measurement of renal arterial blood flow by electromagnetic flow probe after subcutaneous injection of saline, mercuric chloride (4 mg/kg), potassium dichromate (10 mg/kg), or the combination, produced no change over a 2.5-hr period, at 24 hr, and at 48 hr, and the glomerular filtration rate (GFR) of these rats was not affected over the same period of time."
1234872,Tu et al. 1986,An interlaboratory comparison of transformation in Syrian hamster embryo cells with model and coded chemicals,"Three independent laboratories tested eight &quot;model&quot; and five coded chemicals in the Syrian hamster embryo clonal transformation assay system to establish the intra- and interlaboratory reproducibility of the system and to identify sources of variability. When a common cell pool and the same lot of fetal calf serum were used, the three laboratories obtained consensus on the activity of eight model chemicals: five chemicals (benzo(a)pyrene, 7,12-dimethylbenz(a)anthracene, N-methyl-N'-nitro-N-nitrosoguanidine, nitroquinoline-N-oxide, and lead chromate) induced morphological transformation without exogenous metabolic activation and three (N-2-fluorenylacetamide, pyrene, and anthracene) produced no transformation response. Five coded chemicals (2,6-dichloro p-phenylenediamine, 4,4'-oxydianiline, cinnamyl anthranilate, dichlorvos, and reserpine), representative of environmental chemical classes, but not necessarily strong carcinogens, produced more equivocal responses in this interlaboratory study. Thus, while the assay can be used to distinguish between transforming and nontransforming chemicals in some cases, the intrinsic limitations in low transformation frequency and in achieving any dose-response results are major constraints to the use of this system in a routine testing program at the present time. Efforts to increase the transformation frequency or to amplify the expression of the transformed phenotype constitute some of the approaches which should be explored in order to overcome these limitations.","An interlaboratory comparison of transformation in Syrian hamster embryo cells with model and coded chemicals Abs: Three independent laboratories tested eight &quot;model&quot; and five coded chemicals in the Syrian hamster embryo clonal transformation assay system to establish the intra- and interlaboratory reproducibility of the system and to identify sources of variability. When a common cell pool and the same lot of fetal calf serum were used, the three laboratories obtained consensus on the activity of eight model chemicals: five chemicals (benzo(a)pyrene, 7,12-dimethylbenz(a)anthracene, N-methyl-N'-nitro-N-nitrosoguanidine, nitroquinoline-N-oxide, and lead chromate) induced morphological transformation without exogenous metabolic activation and three (N-2-fluorenylacetamide, pyrene, and anthracene) produced no transformation response. Five coded chemicals (2,6-dichloro p-phenylenediamine, 4,4'-oxydianiline, cinnamyl anthranilate, dichlorvos, and reserpine), representative of environmental chemical classes, but not necessarily strong carcinogens, produced more equivocal responses in this interlaboratory study. Thus, while the assay can be used to distinguish between transforming and nontransforming chemicals in some cases, the intrinsic limitations in low transformation frequency and in achieving any dose-response results are major constraints to the use of this system in a routine testing program at the present time. Efforts to increase the transformation frequency or to amplify the expression of the transformed phenotype constitute some of the approaches which should be explored in order to overcome these limitations."
1234871,Flexon et al. 1986,Effects of potassium chromate on atherosclerosis prevention and regression in rabbits,"The effect of intraperitoneal injections of potassium chromate on prevention and regression of atherosclerosis was observed in New Zealand White rabbits. In rabbits fed a 1% cholesterol diet for 90 days, potassium chromate injection was not associated with a significant difference in weight, serum cholesterol, total cholesterol content per 8.5 cm aorta, cholesterol content per gram of aorta or percent intima covered with plaque compared to controls. Similarly, significant differences were not seen in rabbits fed a 1% cholesterol diet for 90 days followed by 60 days of potassium chromate or distilled water injections and a standard diet. These results are in keeping with recent studies suggesting a more limited role for chromium in a variety of lipid-related disorders.","Effects of potassium chromate on atherosclerosis prevention and regression in rabbits Abs: The effect of intraperitoneal injections of potassium chromate on prevention and regression of atherosclerosis was observed in New Zealand White rabbits. In rabbits fed a 1% cholesterol diet for 90 days, potassium chromate injection was not associated with a significant difference in weight, serum cholesterol, total cholesterol content per 8.5 cm aorta, cholesterol content per gram of aorta or percent intima covered with plaque compared to controls. Similarly, significant differences were not seen in rabbits fed a 1% cholesterol diet for 90 days followed by 60 days of potassium chromate or distilled water injections and a standard diet. These results are in keeping with recent studies suggesting a more limited role for chromium in a variety of lipid-related disorders."
1234870,Wedrychowski et al. 1986,Cross-linking of cytokeratins to DNA in vivo by chromium salt and cis-diamminedichloroplatinum(II),"The in vivo cross-linking of cytokeratins to DNA in intact Novikoff ascites hepatoma cells exposed to the chromium salt K2CrO4 and cis-diamminedichloroplatinum(II) (cis-DDP) was studied. Cytokeratin-DNA complexes were obtained by high-speed centrifugation of cells solubilized in buffered 4% sodium dodecyl sulfate. The cytokeratins were identified electrophoretically and immunologically by use of polyclonal and monoclonal antibodies. Time dependence experiments showed that detectable cross-linking occurred after cells were exposed to K2CrO4 for at least 4 h, and the amount of keratin-DNA complexes increased with the incubation time. Each of the three Novikoff ascites hepatoma cytokeratins (p39, p49, and p56) showed a different apparent rate of cross-link formation with DNA. Cytokeratin-DNA complexes were detectable in our system only with K2CrO4 concentrations of 200 microM or greater, and saturation in cross-linking was effected at approximately 2 mM. Higher K2CrO4 concentrations (up to 5 mM) did not produce further significant increases in the amount of cross-linked cytokeratins. Chromium and cis-DDP cross-linked the same cytokeratins at approximately the same ratios; however, both agents cross-linked the major cytokeratins selectively, since not all cytokeratins present in Novikoff hepatoma cell lysates could be cross-linked to DNA. Further evidence of DNA-cytokeratin complexes was obtained by CsCl gradient centrifugation. Our results document the ability of chromate and cis-DDP to produce DNA-cytokeratin cross-links in vivo and show that in live Novikoff hepatoma cells some, but not all, of the components of intermediate filaments are within cross-linking distance of DNA.","Cross-linking of cytokeratins to DNA in vivo by chromium salt and cis-diamminedichloroplatinum(II) Abs: The in vivo cross-linking of cytokeratins to DNA in intact Novikoff ascites hepatoma cells exposed to the chromium salt K2CrO4 and cis-diamminedichloroplatinum(II) (cis-DDP) was studied. Cytokeratin-DNA complexes were obtained by high-speed centrifugation of cells solubilized in buffered 4% sodium dodecyl sulfate. The cytokeratins were identified electrophoretically and immunologically by use of polyclonal and monoclonal antibodies. Time dependence experiments showed that detectable cross-linking occurred after cells were exposed to K2CrO4 for at least 4 h, and the amount of keratin-DNA complexes increased with the incubation time. Each of the three Novikoff ascites hepatoma cytokeratins (p39, p49, and p56) showed a different apparent rate of cross-link formation with DNA. Cytokeratin-DNA complexes were detectable in our system only with K2CrO4 concentrations of 200 microM or greater, and saturation in cross-linking was effected at approximately 2 mM. Higher K2CrO4 concentrations (up to 5 mM) did not produce further significant increases in the amount of cross-linked cytokeratins. Chromium and cis-DDP cross-linked the same cytokeratins at approximately the same ratios; however, both agents cross-linked the major cytokeratins selectively, since not all cytokeratins present in Novikoff hepatoma cell lysates could be cross-linked to DNA. Further evidence of DNA-cytokeratin complexes was obtained by CsCl gradient centrifugation. Our results document the ability of chromate and cis-DDP to produce DNA-cytokeratin cross-links in vivo and show that in live Novikoff hepatoma cells some, but not all, of the components of intermediate filaments are within cross-linking distance of DNA."
1234869,Dorsey and  Cousin 1986,Schistosoma mansoni: a new parenchymal cell in cercariae,"A new type of cell has been identified in cercariae of Schistosoma mansoni. The perikarya (cell bodies) of these cells were located in the body (midsegment), in an area oral to the acetabulum (ventral sucker). Cytoplasmic processes extending from the perikarya ramified throughout the parenchyma of the anterior organ (oral sucker), body, and tail segments by following the path of the nerve processes from the neuropile. The perikarya of these cells had heterochromatic nuclei and a predominance of particulate material and granules (240-360 nm) in their cytoplasm. Aggregates of granules (240-360 nm) and associated vesicles (34 nm) were scattered throughout the cytoplasmic processes of the cells and formed distinct varicosed areas. These processes often connected to the tegument in the midsegment (body) of the cercariae. The granules and associated vesicles reacted (became electron dense) with fixatives reported to be detectors of biogenic amines: The glutaraldehyde/osmium tetroxide fixation procedure rendered the granules electron dense while the glutaraldehyde/chromate/osmium tetroxide fixation procedure rendered the granules and the associated vesicles electron dense. The chromate solution of the latter procedure was responsible for the electron density of the associated vesicles. The morphology of these cells (their long ramifying cytoplasmic processes) and their reaction to chromium suggests that they are probably biogenic aminergic sensory cells.","Schistosoma mansoni: a new parenchymal cell in cercariae Abs: A new type of cell has been identified in cercariae of Schistosoma mansoni. The perikarya (cell bodies) of these cells were located in the body (midsegment), in an area oral to the acetabulum (ventral sucker). Cytoplasmic processes extending from the perikarya ramified throughout the parenchyma of the anterior organ (oral sucker), body, and tail segments by following the path of the nerve processes from the neuropile. The perikarya of these cells had heterochromatic nuclei and a predominance of particulate material and granules (240-360 nm) in their cytoplasm. Aggregates of granules (240-360 nm) and associated vesicles (34 nm) were scattered throughout the cytoplasmic processes of the cells and formed distinct varicosed areas. These processes often connected to the tegument in the midsegment (body) of the cercariae. The granules and associated vesicles reacted (became electron dense) with fixatives reported to be detectors of biogenic amines: The glutaraldehyde/osmium tetroxide fixation procedure rendered the granules electron dense while the glutaraldehyde/chromate/osmium tetroxide fixation procedure rendered the granules and the associated vesicles electron dense. The chromate solution of the latter procedure was responsible for the electron density of the associated vesicles. The morphology of these cells (their long ramifying cytoplasmic processes) and their reaction to chromium suggests that they are probably biogenic aminergic sensory cells."
1234868,Goodgame and  Joy 1986,Relatively long-lived chromium(V) species are produced by the action of glutathione on carcinogenic chromium(VI),"X-Band EPR studies on aqueous solutions of potassium dichromate and gamma-L-glutamyl-L-cysteinylglycine (reduced glutathione) at pH 6-8 have shown the formation of several relatively long-lived chromium(V) species. The major species formed at high glutathione:Cr(VI) ratios is characterised by an EPR band at g = 1.995, but the dominant complex at equimolar ratios produces a signal at g = 1.985.","Relatively long-lived chromium(V) species are produced by the action of glutathione on carcinogenic chromium(VI) Abs: X-Band EPR studies on aqueous solutions of potassium dichromate and gamma-L-glutamyl-L-cysteinylglycine (reduced glutathione) at pH 6-8 have shown the formation of several relatively long-lived chromium(V) species. The major species formed at high glutathione:Cr(VI) ratios is characterised by an EPR band at g = 1.995, but the dominant complex at equimolar ratios produces a signal at g = 1.985."
1234866,Hanisch et al. 1986,Structure of neutral oligosaccharides derived from mucus glycoproteins of human seminal plasma,"The primary structures of nine major saccharide alditols in the fraction of neutral carbohydrates derived from human seminal plasma mucin have been established on the basis of fast atom bombardment and electron impact mass spectrometry combined with methylation analysis, exoglycosidase digestion, and CrO3 oxidation, as follows. Formula: see text.","Structure of neutral oligosaccharides derived from mucus glycoproteins of human seminal plasma Abs: The primary structures of nine major saccharide alditols in the fraction of neutral carbohydrates derived from human seminal plasma mucin have been established on the basis of fast atom bombardment and electron impact mass spectrometry combined with methylation analysis, exoglycosidase digestion, and CrO3 oxidation, as follows. Formula: see text."
1234865,Banner et al. 1986,"Experimental chelation therapy in chromium, lead, and boron intoxication with N-acetylcysteine and other compounds","The usefulness of N-acetylcysteine (NAC) as a chelating agent was studied for the toxin potassium dichromate, lead tetraacetate, and boric acid. Mature Sprague-Dawley rats were intoxicated with these substances and placed in metabolic cages. Urinary excretion rates of intoxicant and total urine volume were determined during treatment with N-acetylcysteine, calcium EDTA, and/or dimercaptosuccinic acid, N-acetylcysteine proved to be the most effective agent at increasing the excretion of chromium and boron and was also able to reverse the oliguria associated with these toxins. Dimercaptosuccinic acid was most effective at the chelation of lead. NAC did not increase the excretion of lead. We conclude that NAC may be useful in intoxications due to chromate and borate and is effective at reversing the oliguria associated with these intoxicants.","Experimental chelation therapy in chromium, lead, and boron intoxication with N-acetylcysteine and other compounds Abs: The usefulness of N-acetylcysteine (NAC) as a chelating agent was studied for the toxin potassium dichromate, lead tetraacetate, and boric acid. Mature Sprague-Dawley rats were intoxicated with these substances and placed in metabolic cages. Urinary excretion rates of intoxicant and total urine volume were determined during treatment with N-acetylcysteine, calcium EDTA, and/or dimercaptosuccinic acid, N-acetylcysteine proved to be the most effective agent at increasing the excretion of chromium and boron and was also able to reverse the oliguria associated with these toxins. Dimercaptosuccinic acid was most effective at the chelation of lead. NAC did not increase the excretion of lead. We conclude that NAC may be useful in intoxications due to chromate and borate and is effective at reversing the oliguria associated with these intoxicants."
1234864,Levy et al. 1986,Investigation of the potential carcinogenicity of a range of chromium containing materials on rat lung,"Twenty one chromium containing materials were examined for carcinogenic activity in a two year study using an intrabronchial pellet implantation system whereby pellets loaded with test material were surgically implanted into the lower left bronchus of rats. The principal aim of the study was to extend our knowledge of the carcinogenic potential of chromium compounds and, in particular, chromates (Cr6+). A statistically significant incidence of treatment related lung tumours was found with some sparingly soluble chromate materials. All tumours were large keratinizing squamous carcinomas of the left lung, except for a single left lung adenocarcinoma and two left lung anaplastic carcinomas. No bronchial carcinomas (0/100) were seen in the negative control group (blank pellet loaded with cholesterol), whereas bronchial carcinomas (22/48 and 25/100) occurred in the two positive control groups which received pellets loaded with 20-methylcholanthrene and calcium chromate respectively. Among the 20 test materials, only three groups gave statistically significant numbers of bronchial carcinomas. Two of these were groups receiving different samples of strontium chromate which gave 43/99 and 62/99 tumours. The third group, zinc chromate (low solubility), gave 5/100 bronchial carcinomas. A further zinc chromate group (Norge composition) produced 3/100 bronchial carcinomas which was not statistically significant. A few lung tumours were observed in other test groups.","Investigation of the potential carcinogenicity of a range of chromium containing materials on rat lung Abs: Twenty one chromium containing materials were examined for carcinogenic activity in a two year study using an intrabronchial pellet implantation system whereby pellets loaded with test material were surgically implanted into the lower left bronchus of rats. The principal aim of the study was to extend our knowledge of the carcinogenic potential of chromium compounds and, in particular, chromates (Cr6+). A statistically significant incidence of treatment related lung tumours was found with some sparingly soluble chromate materials. All tumours were large keratinizing squamous carcinomas of the left lung, except for a single left lung adenocarcinoma and two left lung anaplastic carcinomas. No bronchial carcinomas (0/100) were seen in the negative control group (blank pellet loaded with cholesterol), whereas bronchial carcinomas (22/48 and 25/100) occurred in the two positive control groups which received pellets loaded with 20-methylcholanthrene and calcium chromate respectively. Among the 20 test materials, only three groups gave statistically significant numbers of bronchial carcinomas. Two of these were groups receiving different samples of strontium chromate which gave 43/99 and 62/99 tumours. The third group, zinc chromate (low solubility), gave 5/100 bronchial carcinomas. A further zinc chromate group (Norge composition) produced 3/100 bronchial carcinomas which was not statistically significant. A few lung tumours were observed in other test groups."
1234863,Sugiyama et al. 1986,Characterization of DNA lesions induced by CaCrO4 in synchronous and asynchronous cultured mammalian cells,"Alkaline elution studies demonstrated CaCrO4-induced DNA single strand breaks and DNA-protein crosslinks. DNA single strand breaks increased following treatment with 10-400 microM CaCrO4 in Chinese hamster ovary cells maintained with a minimal salts/glucose medium. DNA single strand breaks were rapidly repaired when extracellular CaCrO4 was removed even following exposure levels of CaCrO4 (200 microM for 2 hr) which reduced survival to 0.6%. Under these exposure conditions the trypan blue exclusion was greater than 80%, whereas cell growth was inhibited by 46% within 24 hr. The DNA-protein crosslinks induced by 10 microM CaCrO4 were repaired in the absence of metal within 24 hr. In contrast, the amount of DNA-protein crosslinks measured 24 hr after a 2-hr treatment with 50, 100, and 200 microM CaCrO4 remained unchanged at the 50 microM level or increased at the two higher concentrations. Thus, at concentrations of 50 microM or greater there was no repair of the DNA protein crosslinks, and this may have been due to cytotoxicity of the metal. CaCrO4 at 10 or 25 microM exposure for 6 hr also induced DNA-protein crosslinking in Chinese hamster ovary cells maintained in normal tissue culture growth media. The lack of repair of DNA-protein crosslinks at the 25 microM level, which did not substantially reduce cell survival, indicated the persistence of these lesions in a noncytotoxic form. Uptake of CaCrO4 was linear with all of the concentrations tested. Analysis of the cell cycle sensitivity to CaCrO4 revealed that cells in early S phase were the most sensitive to the cytotoxic and strand breaking activity of CaCrO4. Compared with other phases of the cell cycle, there was also an elevated level of DNA-protein crosslinks when cells were treated in early S phase and incubated 24 hr without CaCrO4. These results implicate the DNA-protein crosslink as an important lesion that may be responsible for the cytotoxic and carcinogenic properties of chromate.","Characterization of DNA lesions induced by CaCrO4 in synchronous and asynchronous cultured mammalian cells Abs: Alkaline elution studies demonstrated CaCrO4-induced DNA single strand breaks and DNA-protein crosslinks. DNA single strand breaks increased following treatment with 10-400 microM CaCrO4 in Chinese hamster ovary cells maintained with a minimal salts/glucose medium. DNA single strand breaks were rapidly repaired when extracellular CaCrO4 was removed even following exposure levels of CaCrO4 (200 microM for 2 hr) which reduced survival to 0.6%. Under these exposure conditions the trypan blue exclusion was greater than 80%, whereas cell growth was inhibited by 46% within 24 hr. The DNA-protein crosslinks induced by 10 microM CaCrO4 were repaired in the absence of metal within 24 hr. In contrast, the amount of DNA-protein crosslinks measured 24 hr after a 2-hr treatment with 50, 100, and 200 microM CaCrO4 remained unchanged at the 50 microM level or increased at the two higher concentrations. Thus, at concentrations of 50 microM or greater there was no repair of the DNA protein crosslinks, and this may have been due to cytotoxicity of the metal. CaCrO4 at 10 or 25 microM exposure for 6 hr also induced DNA-protein crosslinking in Chinese hamster ovary cells maintained in normal tissue culture growth media. The lack of repair of DNA-protein crosslinks at the 25 microM level, which did not substantially reduce cell survival, indicated the persistence of these lesions in a noncytotoxic form. Uptake of CaCrO4 was linear with all of the concentrations tested. Analysis of the cell cycle sensitivity to CaCrO4 revealed that cells in early S phase were the most sensitive to the cytotoxic and strand breaking activity of CaCrO4. Compared with other phases of the cell cycle, there was also an elevated level of DNA-protein crosslinks when cells were treated in early S phase and incubated 24 hr without CaCrO4. These results implicate the DNA-protein crosslink as an important lesion that may be responsible for the cytotoxic and carcinogenic properties of chromate."
1234862,Giannotti et al. 1986,Langerhans cells are not damaged in contact allergic reactions in humans,Fifteen biopsies from contact allergic reactions in sensitized patients were taken at different time intervals after application of simple chemicals. Two different procedures for electron microscopy were done. No signs of damage were ever seen in Langerhans cells. The authors are therefore of the opinion that there is still no proof for a target role of Langerhans cells in contact allergic reactions in humans.,Langerhans cells are not damaged in contact allergic reactions in humans Abs: Fifteen biopsies from contact allergic reactions in sensitized patients were taken at different time intervals after application of simple chemicals. Two different procedures for electron microscopy were done. No signs of damage were ever seen in Langerhans cells. The authors are therefore of the opinion that there is still no proof for a target role of Langerhans cells in contact allergic reactions in humans.
1234861,LaVelle 1986,Potassium chromate potentiates frameshift mutagenesis in E. coli and S. typhimurium,"Possible comutagenic effects of chromate on frameshift mutagenesis were studied in bacterial assays. In these experiments, cells were treated with potassium chromate and 9-aminoacridine either singly or in combination. Results were analyzed to detect synergistic, additive and antagonistic responses. Data from these investigations show a clear potentiation of 9-aminoacridine-induced mutagenesis in the presence of chromate in S. typhimurium strain TA1537. Results from cell viability assays shows that the effect is not due to a toxicity artifact. Similar results are obtained in E. coli strains 343/358 (repair-proficient parental strain), 343/415 (recA-deficient), and 343/435 (mismatch-repair-deficient). These data indicate the neither induction of recA-protein nor inhibition of mismatch repair is involved in the action of chromate. In E. coli strain 343/447 (DNA polymerase I deficient), the potentiation was observed at lower concentrations of chromate. This finding suggests that polymerase I functions in recovery of cells from 9-aminoacridine-induced DNA damage and that its absence allows some of this damage to be dealt with in a manner which promotes mutagenesis in the presence of chromate. One possible explanation of these findings is that chromate and 9-aminoacridine react chemically to produce a unique mutagen and that damage caused by this mutagen is repaired via some excision process. However, no reaction between chromate and 9-aminoacridine could be detected by TLC under conditions similar to those in the bacterial assays, even at very high concentrations of both agents. Thus, it seems most likely that the potentiation is due to some action of chromate on repair and/or replication at sites of 9-aminoacridine intercalation. Chromate appears, then, to have significant comutagenic actions in bacterial systems.","Potassium chromate potentiates frameshift mutagenesis in E. coli and S. typhimurium Abs: Possible comutagenic effects of chromate on frameshift mutagenesis were studied in bacterial assays. In these experiments, cells were treated with potassium chromate and 9-aminoacridine either singly or in combination. Results were analyzed to detect synergistic, additive and antagonistic responses. Data from these investigations show a clear potentiation of 9-aminoacridine-induced mutagenesis in the presence of chromate in S. typhimurium strain TA1537. Results from cell viability assays shows that the effect is not due to a toxicity artifact. Similar results are obtained in E. coli strains 343/358 (repair-proficient parental strain), 343/415 (recA-deficient), and 343/435 (mismatch-repair-deficient). These data indicate the neither induction of recA-protein nor inhibition of mismatch repair is involved in the action of chromate. In E. coli strain 343/447 (DNA polymerase I deficient), the potentiation was observed at lower concentrations of chromate. This finding suggests that polymerase I functions in recovery of cells from 9-aminoacridine-induced DNA damage and that its absence allows some of this damage to be dealt with in a manner which promotes mutagenesis in the presence of chromate. One possible explanation of these findings is that chromate and 9-aminoacridine react chemically to produce a unique mutagen and that damage caused by this mutagen is repaired via some excision process. However, no reaction between chromate and 9-aminoacridine could be detected by TLC under conditions similar to those in the bacterial assays, even at very high concentrations of both agents. Thus, it seems most likely that the potentiation is due to some action of chromate on repair and/or replication at sites of 9-aminoacridine intercalation. Chromate appears, then, to have significant comutagenic actions in bacterial systems."
1234860,Bayly et al. 1986,A reproducible means of studying acute renal failure in the horse,"Acute renal failure was produced in 5 ponies which had received mercuric chloride (0.25 mg/kg) and potassium dichromate (3 mg/kg) intravenously each day for 5 days. Failure was due to acute nephrosis. This was indicated clinically by daily monitoring of the urine output, and B-mode ultrasonography of both kidneys after administering the fifth dose of the chemical agents. Euthanasia was performed after days 14, 9, 5, 8 and 5 respectively in each of the ponies, and the presence of renal disease confirmed by gross and microscopic post mortem examination. The nature of the kidney lesions observed in each animal was consistent, indicating that the induction of renal disease in this manner was reproducible and represented a means by which the pathophysiologic and biochemical development of equine acute renal failure might be studied.","A reproducible means of studying acute renal failure in the horse Abs: Acute renal failure was produced in 5 ponies which had received mercuric chloride (0.25 mg/kg) and potassium dichromate (3 mg/kg) intravenously each day for 5 days. Failure was due to acute nephrosis. This was indicated clinically by daily monitoring of the urine output, and B-mode ultrasonography of both kidneys after administering the fifth dose of the chemical agents. Euthanasia was performed after days 14, 9, 5, 8 and 5 respectively in each of the ponies, and the presence of renal disease confirmed by gross and microscopic post mortem examination. The nature of the kidney lesions observed in each animal was consistent, indicating that the induction of renal disease in this manner was reproducible and represented a means by which the pathophysiologic and biochemical development of equine acute renal failure might be studied."
1234859,Bayly et al. 1986,Serum and urinary biochemistry and enzyme changes in ponies with acute renal failure,"Serum and urinary biochemical changes were recorded in 5 ponies in which acute tubular nephrosis had been induced over 5 days with mercuric chloride and potassium dichromate. Serum osmolality, the serum concentrations of urea nitrogen, creatinine, sodium, potassium and chloride, and blood pH and blood gases were measured daily for 14 days or until humane euthanasia was performed. Levels of the same substances were quantitated daily in urine. In addition, routine urinalyses and determination of urinary gamma glutamyl transferase (GGT) activity were performed on each sample. Changes in the values of the urinary variables preceded alterations in the serum value of the same substance by at least one day. The first notable abnormality detected was in urinary GGT activities. These changes occurred up to 6 days before the detection of azotemia. It was concluded that acute equine renal injury could be diagnosed earliest with biochemical testing of urine. Measurement of urinary GGT levels represents a means by which proximal tubular disease in equidae could be diagnosed in its developmental stages.","Serum and urinary biochemistry and enzyme changes in ponies with acute renal failure Abs: Serum and urinary biochemical changes were recorded in 5 ponies in which acute tubular nephrosis had been induced over 5 days with mercuric chloride and potassium dichromate. Serum osmolality, the serum concentrations of urea nitrogen, creatinine, sodium, potassium and chloride, and blood pH and blood gases were measured daily for 14 days or until humane euthanasia was performed. Levels of the same substances were quantitated daily in urine. In addition, routine urinalyses and determination of urinary gamma glutamyl transferase (GGT) activity were performed on each sample. Changes in the values of the urinary variables preceded alterations in the serum value of the same substance by at least one day. The first notable abnormality detected was in urinary GGT activities. These changes occurred up to 6 days before the detection of azotemia. It was concluded that acute equine renal injury could be diagnosed earliest with biochemical testing of urine. Measurement of urinary GGT levels represents a means by which proximal tubular disease in equidae could be diagnosed in its developmental stages."
1234856,Sugiyama et al. 1986,"Comparison of DNA lesions and cytotoxicity induced by calcium chromate in human, mouse, and hamster cell lines","DNA lesions, cytotoxicity, and cellular uptake of CaCrO4 were compared in Chinese hamster ovary, in mouse embryo fibroblast C3H10T1/2, and in human osteosarcoma cells. The concentration of CaCrO4 that reduced colony formation by 50% was 2- or 3-fold less in human osteosarcoma cells than in C3H10T1/2 or Chinese hamster ovary cells. Alkaline elution studies showed that CaCrO4 induced DNA single strand breaks in a concentration dependent manner in all three cell lines. However, the human cells exhibited four times more breaks than the hamster cells and two times more than C3H10T1/2 cells when the CaCrO4 exposure conditions were equivalent. Alkaline elution studies also demonstrated the formation of DNA-protein cross-links by CaCrO4 in all three cell lines. In hamster and mouse cells the induction of these DNA-protein cross-links was dependent on concentrations that ranged from 5 to 50 microM for 6 h; however, the cross-links were saturated at 25 microM in human cells and at 50 microM in mouse and hamster cells. The level of cross-links was four times greater in the human cells compared to the mouse cells and was a factor of 2 greater in the hamster cells compared to the mouse cells. The uptake of CaCrO4 was linear with respect to time and concentration. Uptake of CaCrO4 was equivalent in the human and mouse cells, but was a factor of 4 less in the hamster cells. The single strand breaks were almost entirely repaired after an 18-h incubation in metal free medium in all three cell lines, whereas DNA-protein cross-links persisted in these cell lines in proportion to their initial levels. These results demonstrate differences in the sensitivity of human, hamster, and mouse cells to CaCrO4 and suggest that the repair-resistant DNA-protein cross-link may be important in mediating the long term toxic and carcinogenic effects of CaCrO4.","Comparison of DNA lesions and cytotoxicity induced by calcium chromate in human, mouse, and hamster cell lines Abs: DNA lesions, cytotoxicity, and cellular uptake of CaCrO4 were compared in Chinese hamster ovary, in mouse embryo fibroblast C3H10T1/2, and in human osteosarcoma cells. The concentration of CaCrO4 that reduced colony formation by 50% was 2- or 3-fold less in human osteosarcoma cells than in C3H10T1/2 or Chinese hamster ovary cells. Alkaline elution studies showed that CaCrO4 induced DNA single strand breaks in a concentration dependent manner in all three cell lines. However, the human cells exhibited four times more breaks than the hamster cells and two times more than C3H10T1/2 cells when the CaCrO4 exposure conditions were equivalent. Alkaline elution studies also demonstrated the formation of DNA-protein cross-links by CaCrO4 in all three cell lines. In hamster and mouse cells the induction of these DNA-protein cross-links was dependent on concentrations that ranged from 5 to 50 microM for 6 h; however, the cross-links were saturated at 25 microM in human cells and at 50 microM in mouse and hamster cells. The level of cross-links was four times greater in the human cells compared to the mouse cells and was a factor of 2 greater in the hamster cells compared to the mouse cells. The uptake of CaCrO4 was linear with respect to time and concentration. Uptake of CaCrO4 was equivalent in the human and mouse cells, but was a factor of 4 less in the hamster cells. The single strand breaks were almost entirely repaired after an 18-h incubation in metal free medium in all three cell lines, whereas DNA-protein cross-links persisted in these cell lines in proportion to their initial levels. These results demonstrate differences in the sensitivity of human, hamster, and mouse cells to CaCrO4 and suggest that the repair-resistant DNA-protein cross-link may be important in mediating the long term toxic and carcinogenic effects of CaCrO4."
1234855,Wiegand et al. 1986,Disposition of a soluble chromate in the isolated perfused rat liver,"The uptake of potassium dichromate in the isolated perfused rat liver was almost complete after one hour of perfusion. No significant sex differences in chromium distribution were observed. At the end of the experiments (one hour), about 60% of the applied Cr(VI) dose (312 micrograms Cr/liver) was located in the cytosol, 14% was in the mitochondria, 9% in the microsomal pellet and 2% was associated with the nuclei. Gel chromatography of the cytosol showed that most of the chromium was in fractions with an apparent molecular weight of 6000 Da and absorption maxima at 410 nm and 548 nm. Similar optical properties and molecular weight are characteristic of GSH-Cr complexes formed by reaction of Cr(VI) with GSH in vitro.","Disposition of a soluble chromate in the isolated perfused rat liver Abs: The uptake of potassium dichromate in the isolated perfused rat liver was almost complete after one hour of perfusion. No significant sex differences in chromium distribution were observed. At the end of the experiments (one hour), about 60% of the applied Cr(VI) dose (312 micrograms Cr/liver) was located in the cytosol, 14% was in the mitochondria, 9% in the microsomal pellet and 2% was associated with the nuclei. Gel chromatography of the cytosol showed that most of the chromium was in fractions with an apparent molecular weight of 6000 Da and absorption maxima at 410 nm and 548 nm. Similar optical properties and molecular weight are characteristic of GSH-Cr complexes formed by reaction of Cr(VI) with GSH in vitro."
1234854,Hoffman et al. 1986,Direct measurements on individual microcapsule dissolution as a tool for determination of release mechanism,"A method is described for simultaneous microscopic observation of individual microcapsule core material dissolution together with quantitative measurement of the individual kinetics of release of the contents. These may be conductimetric in the case of ionized materials or spectrophotometric otherwise. This enables correlation of changes in core surface area during dissolution with kinetics. Surprisingly, both ethyl cellulose- and polymethacrylate-coated cores of potassium dichromate crystals, used as a model, showed localized internal dissolution universally, providing evidence of the exit of the salt via pores in the membrane, in spite of the kinetics being invariably zero order, as expected for individual microcapsules. The advantages of the method are presented.","Direct measurements on individual microcapsule dissolution as a tool for determination of release mechanism Abs: A method is described for simultaneous microscopic observation of individual microcapsule core material dissolution together with quantitative measurement of the individual kinetics of release of the contents. These may be conductimetric in the case of ionized materials or spectrophotometric otherwise. This enables correlation of changes in core surface area during dissolution with kinetics. Surprisingly, both ethyl cellulose- and polymethacrylate-coated cores of potassium dichromate crystals, used as a model, showed localized internal dissolution universally, providing evidence of the exit of the salt via pores in the membrane, in spite of the kinetics being invariably zero order, as expected for individual microcapsules. The advantages of the method are presented."
1234853,Lofthus et al. 1986,"Metabolism of testosterone to 17 beta-hydroxy-5 alpha-androstane-3-one and 5 alpha-androstane-3 alpha, 17 beta-diol in alveolar macrophages from rat lung--II. Effects of intratracheal instillation of 3.4 mumol K2Cr2O7","Activity of the steroid 5 alpha-reductase in pulmonary alveolar macrophages from adult male rats has been investigated in vitro. Intratracheal instillation of 3.4 mumol K2Cr2O7 lowered the enzyme activity within 6 h, and the reduction was significant on the subsequent 2, 4 and 7 days. The activity of this enzyme was significantly decreased only 6 and 24 h after instillation when measured in the 800 g supernatant fraction of whole lung. Instillation of 3.4 mumol K2Cr2O7 increased serum levels of corticosterone. Serum levels of triiodothyronine and thyroxine decreased except for a transient increase 3 h after the K2Cr2O7 instillation. Subcutaneous administration of 200 micrograms dexamethasone/100 g b.wt, 200 micrograms/100 g b.wt of testosterone, 17 beta-hydroxy-5 alpha-androstane-3-one (5 alpha-DHT), dehydroepiandrosterone or corticosterone had no effect on the 5 alpha-reductase activity of the pulmonary alveolar macrophages within 12 h. The combined treatment with dexamethasone s.c. and intratracheal instillation of 3.4 mumol K2Cr2O7 reduced the steroid 5 alpha-reductase activity in the pulmonary alveolar macrophages to about 25% of controls. Measurement of the steroid 5 alpha-reductase activity in pulmonary alveolar macrophages as an index of lung damage when exposed to toxic material is discussed.","Metabolism of testosterone to 17 beta-hydroxy-5 alpha-androstane-3-one and 5 alpha-androstane-3 alpha, 17 beta-diol in alveolar macrophages from rat lung--II. Effects of intratracheal instillation of 3.4 mumol K2Cr2O7 Abs: Activity of the steroid 5 alpha-reductase in pulmonary alveolar macrophages from adult male rats has been investigated in vitro. Intratracheal instillation of 3.4 mumol K2Cr2O7 lowered the enzyme activity within 6 h, and the reduction was significant on the subsequent 2, 4 and 7 days. The activity of this enzyme was significantly decreased only 6 and 24 h after instillation when measured in the 800 g supernatant fraction of whole lung. Instillation of 3.4 mumol K2Cr2O7 increased serum levels of corticosterone. Serum levels of triiodothyronine and thyroxine decreased except for a transient increase 3 h after the K2Cr2O7 instillation. Subcutaneous administration of 200 micrograms dexamethasone/100 g b.wt, 200 micrograms/100 g b.wt of testosterone, 17 beta-hydroxy-5 alpha-androstane-3-one (5 alpha-DHT), dehydroepiandrosterone or corticosterone had no effect on the 5 alpha-reductase activity of the pulmonary alveolar macrophages within 12 h. The combined treatment with dexamethasone s.c. and intratracheal instillation of 3.4 mumol K2Cr2O7 reduced the steroid 5 alpha-reductase activity in the pulmonary alveolar macrophages to about 25% of controls. Measurement of the steroid 5 alpha-reductase activity in pulmonary alveolar macrophages as an index of lung damage when exposed to toxic material is discussed."
1234852,Goh and  Kwok 1986,The influence of temperature on the concentration homogeneity of patch test materials,"The concentration homogeneity of nickel sulphate 4.8% pet. and potassium dichromate 0.5% pet. in patch test materials appeared to become less homogeneous if stored at room temperature compared storage at 4 degrees C, after 2 months. The coefficient of variation of concentration for nickel sulphate after storage at 4 degrees C was 3.0883%, and at room temperature 25.3098%. The coefficient of variation for potassium dichromate after storage at 4 degrees C was 4.6324% and at room temperature 9.6334%. This indicates that patch test materials containing nickel sulphate and potassium dichromate should be kept refrigerated in the tropics.","The influence of temperature on the concentration homogeneity of patch test materials Abs: The concentration homogeneity of nickel sulphate 4.8% pet. and potassium dichromate 0.5% pet. in patch test materials appeared to become less homogeneous if stored at room temperature compared storage at 4 degrees C, after 2 months. The coefficient of variation of concentration for nickel sulphate after storage at 4 degrees C was 3.0883%, and at room temperature 25.3098%. The coefficient of variation for potassium dichromate after storage at 4 degrees C was 4.6324% and at room temperature 9.6334%. This indicates that patch test materials containing nickel sulphate and potassium dichromate should be kept refrigerated in the tropics."
1234849,Cawthorn et al. 1986,"In vitro excystation of Sarcocystis capracanis, Sarcocystis cruzi and Sarcocystis tenella (Apicomplexa)","Improved rates of in vitro excystation of sporozoites from sporocysts of Sarcocystis capracanis, Sarcocystis cruzi, and Sarcocystis tenella were obtained by pretreating sporocysts with an aqueous sodium hypochlorite (NaOCl) solution followed by incubation in excysting fluid (EF). After pretreatment with NaOCl, sporocysts were washed 4 times in Hanks' balanced salt solution and then incubated in various EF (pH 7.4) at 38.5 C in 5% CO2-95% air. Maximum rates of excystation (free sporozoites/(sporozoites in sporocysts + free sporozoites) X 100) for all 3 species of Sarcocystis occurred at 4 hr after incubation in EF. These rates were 17% for S. capracanis after incubation in EF containing 2% trypsin + 10% caprine bile; 90% for S. cruzi in 2% trypsin + 10% bovine bile; and 20% for S. tenella in 2% trypsin + 10% caprine bile. Only a 40% excystation rate occurred in sporocysts of S. cruzi that had been stored previously for 14 days in aqueous potassium dichromate. Excysted sporozoites of S. capracanis, S. cruzi, and S. tenella penetrated and developed to mature meronts in bovine pulmonary artery endothelial cells or bovine monocytes.","In vitro excystation of Sarcocystis capracanis, Sarcocystis cruzi and Sarcocystis tenella (Apicomplexa) Abs: Improved rates of in vitro excystation of sporozoites from sporocysts of Sarcocystis capracanis, Sarcocystis cruzi, and Sarcocystis tenella were obtained by pretreating sporocysts with an aqueous sodium hypochlorite (NaOCl) solution followed by incubation in excysting fluid (EF). After pretreatment with NaOCl, sporocysts were washed 4 times in Hanks' balanced salt solution and then incubated in various EF (pH 7.4) at 38.5 C in 5% CO2-95% air. Maximum rates of excystation (free sporozoites/(sporozoites in sporocysts + free sporozoites) X 100) for all 3 species of Sarcocystis occurred at 4 hr after incubation in EF. These rates were 17% for S. capracanis after incubation in EF containing 2% trypsin + 10% caprine bile; 90% for S. cruzi in 2% trypsin + 10% bovine bile; and 20% for S. tenella in 2% trypsin + 10% caprine bile. Only a 40% excystation rate occurred in sporocysts of S. cruzi that had been stored previously for 14 days in aqueous potassium dichromate. Excysted sporozoites of S. capracanis, S. cruzi, and S. tenella penetrated and developed to mature meronts in bovine pulmonary artery endothelial cells or bovine monocytes."
1234848,Weston et al. 1986,"Prevalence of positive epicutaneous tests among infants, children, and adolescents","We studied 314 otherwise healthy children younger than 18 years of age with epicutaneous testing, and found that 20% of those tested had at least one positive epicutaneous test result. Neomycin, nickel, and potassium dichromate were the most prevalent allergens detected in our study group. We found that sensitization occurred at less than 5 years of age for all but fragrance allergens. Aluminum chambers and the American Academy of Dermatology Patch Test Kit were found to be safe for use in infants, children, and adolescents.","Prevalence of positive epicutaneous tests among infants, children, and adolescents Abs: We studied 314 otherwise healthy children younger than 18 years of age with epicutaneous testing, and found that 20% of those tested had at least one positive epicutaneous test result. Neomycin, nickel, and potassium dichromate were the most prevalent allergens detected in our study group. We found that sensitization occurred at less than 5 years of age for all but fragrance allergens. Aluminum chambers and the American Academy of Dermatology Patch Test Kit were found to be safe for use in infants, children, and adolescents."
1234846,Tomsig and  Pellegrino de Iraldi 1987,"Effect of collidine (2,4,6-trimethylpyridine) on the osmiophilia and chromaffin reaction in the synaptic vesicles of rat pineal nerves","Rat pineal nerve endings contain a population of small and of large synaptic vesicles that are either electron lucent or have electron-dense cores. It has been reported that their osmiophilia is eliminated when collidine buffer is used in the fixation procedure. We investigated this effect and found that osmium tetroxide and potassium dichromate reactivity were abolished when excised pineal glands were briefly incubated with collidine buffer before glutaraldehyde-cacodylate fixation. Such an effect was not observed when collidine was applied after fixation. Glands that had been fixed in glutaraldehyde or osmium tetroxide buffered with collidine exhibited a peripheral zone containing reactive synaptic vesicles and a deeper, central zone where such reactivity was absent. These results indicate that the effect of collidine is due to depletion of monoamines rather than to chemical blockage of their reactivity, and further suggest that collidine has a higher rate of penetration into tissues than the tested fixatives.","Effect of collidine (2,4,6-trimethylpyridine) on the osmiophilia and chromaffin reaction in the synaptic vesicles of rat pineal nerves Abs: Rat pineal nerve endings contain a population of small and of large synaptic vesicles that are either electron lucent or have electron-dense cores. It has been reported that their osmiophilia is eliminated when collidine buffer is used in the fixation procedure. We investigated this effect and found that osmium tetroxide and potassium dichromate reactivity were abolished when excised pineal glands were briefly incubated with collidine buffer before glutaraldehyde-cacodylate fixation. Such an effect was not observed when collidine was applied after fixation. Glands that had been fixed in glutaraldehyde or osmium tetroxide buffered with collidine exhibited a peripheral zone containing reactive synaptic vesicles and a deeper, central zone where such reactivity was absent. These results indicate that the effect of collidine is due to depletion of monoamines rather than to chemical blockage of their reactivity, and further suggest that collidine has a higher rate of penetration into tissues than the tested fixatives."
1234844,McGregor et al. 1987,Responses of the L5178Y tk+/tk- mouse lymphoma cell forward mutation assay to coded chemicals. I: Results for nine compounds,"Nine substances were tested for their mutagenic potential in the L5178Y tk+/tk- mouse lymphoma cell forward mutation assay, by means of procedures based upon those described by Clive and Spector (Mutat Res 44:269-278, 1975) and Clive et al (Mutat Res 59:61-108, 1979). Cultures were exposed to the chemicals for 4 hr, then cultured for 2 days before plating in soft agar with or without trifluorothymidine (TFT), 3 micrograms/ml. The coded chemicals were tested at least twice. Significant responses were obtained with calcium chromate, 3-(chloromethyl)pyridine, 1,2-epoxybutane, monochloroacetic acid, dicyclohexylthiourea, 2,4-diaminophenol hydrochloride, and pentachloroanisole. Apart from pentachloroanisole, rat liver S9 mix was not a requirement for the clearly mutagenic activity of any of these compounds. Compounds not identified as mutagens were 3-amino-1,2,4-triazole and sucrose.","Responses of the L5178Y tk+/tk- mouse lymphoma cell forward mutation assay to coded chemicals. I: Results for nine compounds Abs: Nine substances were tested for their mutagenic potential in the L5178Y tk+/tk- mouse lymphoma cell forward mutation assay, by means of procedures based upon those described by Clive and Spector (Mutat Res 44:269-278, 1975) and Clive et al (Mutat Res 59:61-108, 1979). Cultures were exposed to the chemicals for 4 hr, then cultured for 2 days before plating in soft agar with or without trifluorothymidine (TFT), 3 micrograms/ml. The coded chemicals were tested at least twice. Significant responses were obtained with calcium chromate, 3-(chloromethyl)pyridine, 1,2-epoxybutane, monochloroacetic acid, dicyclohexylthiourea, 2,4-diaminophenol hydrochloride, and pentachloroanisole. Apart from pentachloroanisole, rat liver S9 mix was not a requirement for the clearly mutagenic activity of any of these compounds. Compounds not identified as mutagens were 3-amino-1,2,4-triazole and sucrose."
1234842,Caldas and  Hicks 1987,Intrapulmonary pretreatment by metal-fume components causing inhibition of delayed hypersensitivity,"The effect of administration of chromium (7440473) (Cr) or nickel (7440020) (Ni) components of stainless steel welding fumes in inhibiting cutaneous hypersensitivity evoked by them at a later time was investigated. A water soluble, extractable fraction was prepared from particles produced by manual metal arc welding with stainless steel electrodes (Nicrex-1), which gave fumes rich in Cr and Ni. Groups of five guinea-pigs were given one, two, or three sets of intrapulmonary injections, each set comprising one, three, five, or six injections at daily or alternate daily intervals, and with intervals of 3, 7, 9, 14, or 24 days between the sets or before sensitization. Tolerization pretreatments using two or three sets of three to five intrapulmonary injections of potassium-chromate (7789006) (total dose 42mg/kg) all produced significant reductions in cutaneous hypersensitivity to chromate. Pretreatment sequences of two or three sets of three intrapulmonary injections of welding fume components (total dose equivalent to 100mg/kg of original particles) significantly inhibited the elicitation of sensitization. With three sets of three injections of nickel-sulfate (7786814) (total dose 42mg/kg), followed by sensitization, cutaneous reactions were significantly potentiated. No cross tolerance was found between potassium-chromate and nickel-sulfate. The authors conclude that intrapulmonary pretreatment with chromate specifically inhibits cutaneously induced hypersensitivity, but that pretreatment with a nickel salt causes some potentiation. They further conclude that the overall tolerizing effect of the water soluble welding fume component mixture can be explained in terms of its major component, chromate, exerting the predominant effect and masking any specific potentiation due to nickel.","Intrapulmonary pretreatment by metal-fume components causing inhibition of delayed hypersensitivity Abs: The effect of administration of chromium (7440473) (Cr) or nickel (7440020) (Ni) components of stainless steel welding fumes in inhibiting cutaneous hypersensitivity evoked by them at a later time was investigated. A water soluble, extractable fraction was prepared from particles produced by manual metal arc welding with stainless steel electrodes (Nicrex-1), which gave fumes rich in Cr and Ni. Groups of five guinea-pigs were given one, two, or three sets of intrapulmonary injections, each set comprising one, three, five, or six injections at daily or alternate daily intervals, and with intervals of 3, 7, 9, 14, or 24 days between the sets or before sensitization. Tolerization pretreatments using two or three sets of three to five intrapulmonary injections of potassium-chromate (7789006) (total dose 42mg/kg) all produced significant reductions in cutaneous hypersensitivity to chromate. Pretreatment sequences of two or three sets of three intrapulmonary injections of welding fume components (total dose equivalent to 100mg/kg of original particles) significantly inhibited the elicitation of sensitization. With three sets of three injections of nickel-sulfate (7786814) (total dose 42mg/kg), followed by sensitization, cutaneous reactions were significantly potentiated. No cross tolerance was found between potassium-chromate and nickel-sulfate. The authors conclude that intrapulmonary pretreatment with chromate specifically inhibits cutaneously induced hypersensitivity, but that pretreatment with a nickel salt causes some potentiation. They further conclude that the overall tolerizing effect of the water soluble welding fume component mixture can be explained in terms of its major component, chromate, exerting the predominant effect and masking any specific potentiation due to nickel."
1234837,Syversen and  Jenssen 1987,High hydrostatic pressure potentiation of the toxic effects of chromate in cell culture,"Development of hyperbaric welding has created the need for new occupational health standards. We have used cell cultures to investigate effects of high pressure chromate on the toxicity of the welding-fume component, chromate. The results indicate that pressure caused rounding-up of cells and changes in F-actin filaments, and that these effects were related to the extent of high pressure and independent of exposure duration. When exposing the Flow 5000 cells to chromate (1-5 microM) the amount of disrupted F-actin fibers was found to depend on the concentration applied and the duration of exposure. The amount of cell-associated chromate was the same for 1 h exposure at 1 and 150 bar. The fraction of rounded cells after exposure to 1 microM chromate and 100 bar for 18 h was higher than would be expected if the effects were purely additive.","High hydrostatic pressure potentiation of the toxic effects of chromate in cell culture Abs: Development of hyperbaric welding has created the need for new occupational health standards. We have used cell cultures to investigate effects of high pressure chromate on the toxicity of the welding-fume component, chromate. The results indicate that pressure caused rounding-up of cells and changes in F-actin filaments, and that these effects were related to the extent of high pressure and independent of exposure duration. When exposing the Flow 5000 cells to chromate (1-5 microM) the amount of disrupted F-actin fibers was found to depend on the concentration applied and the duration of exposure. The amount of cell-associated chromate was the same for 1 h exposure at 1 and 150 bar. The fraction of rounded cells after exposure to 1 microM chromate and 100 bar for 18 h was higher than would be expected if the effects were purely additive."
1234836,Jenssen and  Syversen 1987,High hydrostatic pressure and chromate-induced effects on cell cycle kinetics,"Cell cycle kinetics was studied using the quenching of 33258 Hoechst fluorescence by bromodeoxyuridine incorporation to investigate effects of high pressure on the toxicity of a welding fume component--chromate. When exposing the glioma cells to 1 microM K2Cr2O7 at 1 bar, we observed a prolongation of DNA-synthesis phase, whereas cells exposed to 5 microM K2Cr2O7 did not pass through mitosis. Cells exposed to 1 or 5 microM chromate during the last part of DNA synthesis and during mitosis were not delayed in passing through mitosis. High pressure (100 bar) or pretreatment with pressure did not cause changes of cell cycle parameters. The combined exposure of 1 microM K2Cr2O7 and high pressure caused the same effect as observed for 1 microM K2Cr2O7 at 1 atm. However, an extra delay was observed in passing through mitosis for cells exposed to 100-bar pressure during the early part of their cell cycle.","High hydrostatic pressure and chromate-induced effects on cell cycle kinetics Abs: Cell cycle kinetics was studied using the quenching of 33258 Hoechst fluorescence by bromodeoxyuridine incorporation to investigate effects of high pressure on the toxicity of a welding fume component--chromate. When exposing the glioma cells to 1 microM K2Cr2O7 at 1 bar, we observed a prolongation of DNA-synthesis phase, whereas cells exposed to 5 microM K2Cr2O7 did not pass through mitosis. Cells exposed to 1 or 5 microM chromate during the last part of DNA synthesis and during mitosis were not delayed in passing through mitosis. High pressure (100 bar) or pretreatment with pressure did not cause changes of cell cycle parameters. The combined exposure of 1 microM K2Cr2O7 and high pressure caused the same effect as observed for 1 microM K2Cr2O7 at 1 atm. However, an extra delay was observed in passing through mitosis for cells exposed to 100-bar pressure during the early part of their cell cycle."
1234834,Brun et al. 1987,Effect of chromate ion on the membrane of established human cells as measured by uptake of a permeant lipophilic cation,"Cells from the established human cell line NHIK3025 concentrate the permeant lipophilic cation triphenylmethylphosphonium (TPMP+) against a concentration gradient, indicating the existence of an electrical potential across the cell membrane (interior negative). Cells exposed to potassium chromate or dichromate (7.7 mumol Cr/l) for 2 h subsequently showed reduced uptake of TPMP+, whereas similar exposure to a trivalent chromium salt (7.7 mumol/l chromic chloride) had similar uptake of TPMP+ as control cells. These preliminary results suggest that a primary effect of chromate on these cells is to reduce the electrical potential across the cell membrane.","Effect of chromate ion on the membrane of established human cells as measured by uptake of a permeant lipophilic cation Abs: Cells from the established human cell line NHIK3025 concentrate the permeant lipophilic cation triphenylmethylphosphonium (TPMP+) against a concentration gradient, indicating the existence of an electrical potential across the cell membrane (interior negative). Cells exposed to potassium chromate or dichromate (7.7 mumol Cr/l) for 2 h subsequently showed reduced uptake of TPMP+, whereas similar exposure to a trivalent chromium salt (7.7 mumol/l chromic chloride) had similar uptake of TPMP+ as control cells. These preliminary results suggest that a primary effect of chromate on these cells is to reduce the electrical potential across the cell membrane."
1234833,Scholz 1987,"Barentsia matsushimana, a marine entoproct suitable for bioassays",,"Barentsia matsushimana, a marine entoproct suitable for bioassays Abs: "
1234832,Sen et al. 1987,Comparison of the localization of chromosome damage induced by calcium chromate and nickel compounds,"Chromosomal aberrations were studied in Chinese hamster ovary cells and in C3H10T1/2 cells following treatment with NiCl2, crystalline NiS, and CaCrO4. All three compounds caused an increase in chromosomal aberrations in a concentration- and time-dependent fashion. The chromosomal aberrations induced by NiCl2 and crystalline NiS occurred predominantly in heterochromatic regions of the chromosomes. Additionally, treatment of cells with crystalline NiS and to a smaller extent long-term treatment with NiCl2 caused a preferential effect on the condensation state of the heterochromatic long arm of the X-chromosome in hamster cells. In contrast, treatment of cells with CaCrO4 did not induce aberrations preferentially in heterochromatin. These results are interesting because nickel(II), which is thought to be the ultimate carcinogen of nickel compounds, binds poorly to DNA, is weakly mutagenic, but induces chromosome damage, probably because of its interaction with nuclear proteins in heterochromatin. Chromate binds to DNA, is mutagenic, and interacts with chromatin randomly.","Comparison of the localization of chromosome damage induced by calcium chromate and nickel compounds Abs: Chromosomal aberrations were studied in Chinese hamster ovary cells and in C3H10T1/2 cells following treatment with NiCl2, crystalline NiS, and CaCrO4. All three compounds caused an increase in chromosomal aberrations in a concentration- and time-dependent fashion. The chromosomal aberrations induced by NiCl2 and crystalline NiS occurred predominantly in heterochromatic regions of the chromosomes. Additionally, treatment of cells with crystalline NiS and to a smaller extent long-term treatment with NiCl2 caused a preferential effect on the condensation state of the heterochromatic long arm of the X-chromosome in hamster cells. In contrast, treatment of cells with CaCrO4 did not induce aberrations preferentially in heterochromatin. These results are interesting because nickel(II), which is thought to be the ultimate carcinogen of nickel compounds, binds poorly to DNA, is weakly mutagenic, but induces chromosome damage, probably because of its interaction with nuclear proteins in heterochromatin. Chromate binds to DNA, is mutagenic, and interacts with chromatin randomly."
1234831,Dumpert 1987,Embryotoxic effects of environmental chemicals: tests with the South African clawed toad (Xenopus laevis),"In the course of the investigations reported below, it was shown that p-chloroaniline has a lethal effect on the embryos of Xenopus laevis at a concentration of 100 ppm and is development inhibiting (teratogenic) at concentrations of 1 and 10 ppm, respectively. In the case of aniline, a significant development-inhibiting effect was observed at a concentration as low as 1 ppm. A toxic effect was caused by concentrations between 30 and 40 ppm during embryogenesis and by concentrations above 40 ppm during larval development. A very conspicuous finding was an inhibiting effect of 20 to 40 ppm aniline on pigmentation during embryogenesis and of a concentration as low as 1 ppm on the body size of the young toads. In the case of potassium dichromate, it was possible to barely detect a weak development-inhibiting effect during embryogenesis but no development-retarding effect during larval development. Toxic effects of potassium dichromate occurred during embryogenesis at concentrations of 5 and 7.5 ppm and during the larval development at concentrations above 10 ppm. Sodium dodecylbenzenesulfonic acid at a concentration of 50 ppm was found to have such a strong embryolethal effect that 80% of the eggs showed no cell division at all and the remaining 20% developed to only the bicellular stage. A teratogenic effect of this substance was not observed. Phenol, too, was found to be toxic at a concentration of 50 ppm; in contrast to sodium dodecylbenzenesulfonic acid, however, it did not show any lethal effect on the embryos but it did on the tadpoles, mainly in the first stages of larval development. Lower concentrations of phenol (5 and 10 ppm) had a nonsignificant inhibiting effect on the growth of the larvae. A teratogenic effect of phenol was not detected.","Embryotoxic effects of environmental chemicals: tests with the South African clawed toad (Xenopus laevis) Abs: In the course of the investigations reported below, it was shown that p-chloroaniline has a lethal effect on the embryos of Xenopus laevis at a concentration of 100 ppm and is development inhibiting (teratogenic) at concentrations of 1 and 10 ppm, respectively. In the case of aniline, a significant development-inhibiting effect was observed at a concentration as low as 1 ppm. A toxic effect was caused by concentrations between 30 and 40 ppm during embryogenesis and by concentrations above 40 ppm during larval development. A very conspicuous finding was an inhibiting effect of 20 to 40 ppm aniline on pigmentation during embryogenesis and of a concentration as low as 1 ppm on the body size of the young toads. In the case of potassium dichromate, it was possible to barely detect a weak development-inhibiting effect during embryogenesis but no development-retarding effect during larval development. Toxic effects of potassium dichromate occurred during embryogenesis at concentrations of 5 and 7.5 ppm and during the larval development at concentrations above 10 ppm. Sodium dodecylbenzenesulfonic acid at a concentration of 50 ppm was found to have such a strong embryolethal effect that 80% of the eggs showed no cell division at all and the remaining 20% developed to only the bicellular stage. A teratogenic effect of this substance was not observed. Phenol, too, was found to be toxic at a concentration of 50 ppm; in contrast to sodium dodecylbenzenesulfonic acid, however, it did not show any lethal effect on the embryos but it did on the tadpoles, mainly in the first stages of larval development. Lower concentrations of phenol (5 and 10 ppm) had a nonsignificant inhibiting effect on the growth of the larvae. A teratogenic effect of phenol was not detected."
1234830,Sultan 1987,Spectrophotometric determination of paracetamol in drug formulations by oxidation with potassium dichromate,"A rapid spectrophotometric method for determination of paracetamol is described, based on oxidation with dichromate for 15 min in 6M sulphuric acid at 80 degrees , and measurement (at 580 nm) of the chromium(III) formed. The method is applied to the determination of paracetamol in drugs prescribed for colds, coughs and flu. Of the common pharmaceuticals associated with paracetamol, only ascorbic acid and acetylsalicylic acid interfere. The results have been statistically compared with those obtained by the official (BP) and cerium(IV) methods.","Spectrophotometric determination of paracetamol in drug formulations by oxidation with potassium dichromate Abs: A rapid spectrophotometric method for determination of paracetamol is described, based on oxidation with dichromate for 15 min in 6M sulphuric acid at 80 degrees , and measurement (at 580 nm) of the chromium(III) formed. The method is applied to the determination of paracetamol in drugs prescribed for colds, coughs and flu. Of the common pharmaceuticals associated with paracetamol, only ascorbic acid and acetylsalicylic acid interfere. The results have been statistically compared with those obtained by the official (BP) and cerium(IV) methods."
1234829,van Leeuwen et al. 1987,Effects of chemical stress on the population dynamics of Daphnia magna: a comparison of two test procedures,"Ten substances were tested to compare two methods that can be used in chronic toxicity studies with the Cladoceran Daphnia magna. In semistatic experiments with cohorts (life-table studies) survival appeared to be a dominant factor in exponential population growth. Specific inhibition of reproduction as a result of toxic stress was observed only in tests with bromide and 2,4-dichloroaniline. For some substances (cadmium, bichromate, metavanadate, and bromide) individual growth (carapace length) was found to be a sensitive parameter. In intermittent-flow experiments with small expanding populations the yield (carrying capacity) proved to be a highly sensitive parameter, probably owing to the fact that in these tests populations grow logistically, i.e., become additionally stressed by food limitation. Chemically induced reductions in food ingestion and conversion efficiency may thus become very predominant. In view of the place of these crustaceans in the food web such reductions in the carrying capacity would seem to be of great ecotoxicological importance.","Effects of chemical stress on the population dynamics of Daphnia magna: a comparison of two test procedures Abs: Ten substances were tested to compare two methods that can be used in chronic toxicity studies with the Cladoceran Daphnia magna. In semistatic experiments with cohorts (life-table studies) survival appeared to be a dominant factor in exponential population growth. Specific inhibition of reproduction as a result of toxic stress was observed only in tests with bromide and 2,4-dichloroaniline. For some substances (cadmium, bichromate, metavanadate, and bromide) individual growth (carapace length) was found to be a sensitive parameter. In intermittent-flow experiments with small expanding populations the yield (carrying capacity) proved to be a highly sensitive parameter, probably owing to the fact that in these tests populations grow logistically, i.e., become additionally stressed by food limitation. Chemically induced reductions in food ingestion and conversion efficiency may thus become very predominant. In view of the place of these crustaceans in the food web such reductions in the carrying capacity would seem to be of great ecotoxicological importance."
1234828,Sonnenblick et al. 1987,The effect of prolonged treatment with differing doses of chromium on glucose homeostasis in rabbits,"The effect of prolonged treatment with chromium on glucose homeostasis was assessed in rabbits. Thirty-one male rabbits were divided into 6 groups. All were fed for 30 days with a standard ad libitum diet. Twenty-seven rabbits were injected daily during a further 120 days with different doses of potassium chromate (3-20 micrograms) while 4 rabbits served as controls. No significant rise in serum glucose levels was observed, insulin levels were the same in the different groups, and glycosylated hemoglobin concentration also did not change after the administration of chromium. Serum chromium levels increased proportionally to the dose injected to an almost a 14 fold increase in the 20 micrograms chromium treated group. Although others have shown that chromium may have a hyperglycemic effect with inhibition of insulin secretion, we have not been able to confirm this finding.","The effect of prolonged treatment with differing doses of chromium on glucose homeostasis in rabbits Abs: The effect of prolonged treatment with chromium on glucose homeostasis was assessed in rabbits. Thirty-one male rabbits were divided into 6 groups. All were fed for 30 days with a standard ad libitum diet. Twenty-seven rabbits were injected daily during a further 120 days with different doses of potassium chromate (3-20 micrograms) while 4 rabbits served as controls. No significant rise in serum glucose levels was observed, insulin levels were the same in the different groups, and glycosylated hemoglobin concentration also did not change after the administration of chromium. Serum chromium levels increased proportionally to the dose injected to an almost a 14 fold increase in the 20 micrograms chromium treated group. Although others have shown that chromium may have a hyperglycemic effect with inhibition of insulin secretion, we have not been able to confirm this finding."
1234827,Sultan 1987,Determination of aspirin in pharmaceutical preparations by spectrophotometry after oxidation with potassium dichromate,,Determination of aspirin in pharmaceutical preparations by spectrophotometry after oxidation with potassium dichromate Abs: 
1234826,Haberman et al. 1987,The effect of chromate on citrinin-induced renal dysfunction in the rat,"Previous studies in this laboratory revealed an effect of chromate to potentiate the nephrotoxic effects of mercuric ion. Citrinin, an organic anion, is a known nephrotoxin. The present study was undertaken to assess the possible interaction of chromate and citrinin on renal function. Male Sprague-Dawley rats were housed in metabolism cages and injected with citrinin (35 mg/kg), chromate (10 mg/kg) or the combination. The combination of nephrotoxicants caused an increased excretion of urine greater than the sum of the individual responses. A similar response was observed with urinary glucose concentrations and glucose excretion without changes in blood glucose levels. These data indicate that chromate can potentiate the nephrotoxic action of citrinin in the rat.","The effect of chromate on citrinin-induced renal dysfunction in the rat Abs: Previous studies in this laboratory revealed an effect of chromate to potentiate the nephrotoxic effects of mercuric ion. Citrinin, an organic anion, is a known nephrotoxin. The present study was undertaken to assess the possible interaction of chromate and citrinin on renal function. Male Sprague-Dawley rats were housed in metabolism cages and injected with citrinin (35 mg/kg), chromate (10 mg/kg) or the combination. The combination of nephrotoxicants caused an increased excretion of urine greater than the sum of the individual responses. A similar response was observed with urinary glucose concentrations and glucose excretion without changes in blood glucose levels. These data indicate that chromate can potentiate the nephrotoxic action of citrinin in the rat."
1234825,Ruegg et al. 1987,"Differential patterns of injury to the proximal tubule of renal cortical slices following in vitro exposure to mercuric chloride, potassium dichromate, or hypoxic conditions","The innate susceptibility of renal cell types to these agents was investigated using precision-cut rabbit renal cortical slices made perpendicular to the cortical-papillary axis. Slices were incubated in DME/F12 medium containing 10 microM, 100 microM, or 1 mM concentrations of either metal for 12 hr or in Krebs-Hepes buffer gassed with nitrogen (100%) for 0.75 to 5 hr of hypoxic exposure. To simulate postischemic reperfusion, some slices were transferred to vessels gassed with oxygen after an initial hypoxic period. Mercuric chloride (100 microM) exposure resulted in damage to the straight regions of proximal tubules by 12 hr leaving convoluted regions unaffected. Hypoxia (2.25 hr) and potassium dichromate (100 microM for 12 hr) both caused injury to the convoluted proximal tubules without affecting straight proximal tubular regions. Mercury concentrations of 10 microM and 1 mM had no effect or injured all cell types within the slice, respectively. Similar results were observed for hypoxic periods less than 1.5 hr or greater than 3 hr of exposure. Potassium dichromate had no measurable affect at 10 microM, but at 1 mM focal lesions were observed after 4 hr of exposure, and by 12 hr all cell types within the slice were affected. Intracellular potassium content normalized to DNA correlated well, but always preceded the pathological lesions observed. These results demonstrate that injury to specific regions of the proximal tubule by these agents relates to an innate susceptibility of the intoxicated cell type independent of physiologic feedback or blood delivery patterns proposed as mechanisms of selective injury from in vivo studies.","Differential patterns of injury to the proximal tubule of renal cortical slices following in vitro exposure to mercuric chloride, potassium dichromate, or hypoxic conditions Abs: The innate susceptibility of renal cell types to these agents was investigated using precision-cut rabbit renal cortical slices made perpendicular to the cortical-papillary axis. Slices were incubated in DME/F12 medium containing 10 microM, 100 microM, or 1 mM concentrations of either metal for 12 hr or in Krebs-Hepes buffer gassed with nitrogen (100%) for 0.75 to 5 hr of hypoxic exposure. To simulate postischemic reperfusion, some slices were transferred to vessels gassed with oxygen after an initial hypoxic period. Mercuric chloride (100 microM) exposure resulted in damage to the straight regions of proximal tubules by 12 hr leaving convoluted regions unaffected. Hypoxia (2.25 hr) and potassium dichromate (100 microM for 12 hr) both caused injury to the convoluted proximal tubules without affecting straight proximal tubular regions. Mercury concentrations of 10 microM and 1 mM had no effect or injured all cell types within the slice, respectively. Similar results were observed for hypoxic periods less than 1.5 hr or greater than 3 hr of exposure. Potassium dichromate had no measurable affect at 10 microM, but at 1 mM focal lesions were observed after 4 hr of exposure, and by 12 hr all cell types within the slice were affected. Intracellular potassium content normalized to DNA correlated well, but always preceded the pathological lesions observed. These results demonstrate that injury to specific regions of the proximal tubule by these agents relates to an innate susceptibility of the intoxicated cell type independent of physiologic feedback or blood delivery patterns proposed as mechanisms of selective injury from in vivo studies."
1234822,Nohara-Uchida and  Ohashi 1987,Isolation and characterization of major gangliosides from frog liver,"Four major gangliosides isolated from frog liver were characterized by compositional analysis involving GLC and GC-MS, methylation analysis, chromium trioxide oxidation, and enzymatic hydrolysis. The results revealed that the most major ganglioside in the tissue was GM4 containing N-acetylneuraminic acid and the others were GM4 containing N-glycolylneuraminic acid, GD1a, and a fucosyl ganglioside which was tentatively assigned to be alpha-galactosyl alpha-fucosyl GM1. This is the first report describing the presence of GM4 containing N-glycolylneuraminic acid. The fatty acids in both GM4 were mainly alpha-hydroxylated, and those in the fucosyl ganglioside were exclusively nonhydroxy fatty acids. The GD1a contained both nonhydroxy and alpha-hydroxy fatty acids in a ratio of about 3:2. The predominant species were 22:0, 23:0, 24:0, and 24:1 in both species of the fatty acids. The long-chain bases of these four gangliosides consisted of C18-sphingosine and C18-phytosphingosine together with significant amounts of C16 to C19 dihydroxy and trihydroxy bases with iso and anteiso structures.","Isolation and characterization of major gangliosides from frog liver Abs: Four major gangliosides isolated from frog liver were characterized by compositional analysis involving GLC and GC-MS, methylation analysis, chromium trioxide oxidation, and enzymatic hydrolysis. The results revealed that the most major ganglioside in the tissue was GM4 containing N-acetylneuraminic acid and the others were GM4 containing N-glycolylneuraminic acid, GD1a, and a fucosyl ganglioside which was tentatively assigned to be alpha-galactosyl alpha-fucosyl GM1. This is the first report describing the presence of GM4 containing N-glycolylneuraminic acid. The fatty acids in both GM4 were mainly alpha-hydroxylated, and those in the fucosyl ganglioside were exclusively nonhydroxy fatty acids. The GD1a contained both nonhydroxy and alpha-hydroxy fatty acids in a ratio of about 3:2. The predominant species were 22:0, 23:0, 24:0, and 24:1 in both species of the fatty acids. The long-chain bases of these four gangliosides consisted of C18-sphingosine and C18-phytosphingosine together with significant amounts of C16 to C19 dihydroxy and trihydroxy bases with iso and anteiso structures."
1234819,Gumbleton and  Nicholls 1988,Dose-response and time-response biochemical and histological study of potassium dichromate-induced nephrotoxicity in the rat,"This study provides quantitative toxicological data on potassium dichromate-induced renal damage and considers the possible difficulties arising from the non-invasive in vivo assessment of renal damage, with particular attention to enzymuria. Renal damage induced in male Wistar rats by single sc injections of potassium dichromate was assessed 52 to 72 hr after doses ranging from 3 to 20 mg potassium dichromate/kg body weight and throughout a 9-day period following a dose of 20 mg potassium dichromate/kg. The earliest and most sensitive non-invasive functional change in the dose-response and time-response studies was an elevation in the rate of urinary excretion of protein. Evidence of tissue damage was observed with elevations in the urinary excretion rates of the brush border enzymes, gamma-glutamyltransferase, alkaline phosphatase and leucine aminopeptidase, the cytosolic enzymes, aspartate aminotransferase and lactate dehydrogenase and the lysosomal enzyme, N-acetyl-beta-D-glucosaminidase. Such changes occurred as early as the abnormal urinary protein excretion, but returned to control or sub-control values sooner. Urinary brush border enzyme excretion returned to control values within 48 hr following potassium dichromate injection, despite histological and histochemical evidence of extensive renal damage and renal dysfunction. Elevations in plasma aspartate aminotransferase and lactate dehydrogenase levels were observed, but histochemical and isoenzyme studies would be needed to determine the source of these increases. The simplest and most persistent indicators of renal damage were the urinary excretion of protein and N-acetyl-beta-D-glucosaminidase.","Dose-response and time-response biochemical and histological study of potassium dichromate-induced nephrotoxicity in the rat Abs: This study provides quantitative toxicological data on potassium dichromate-induced renal damage and considers the possible difficulties arising from the non-invasive in vivo assessment of renal damage, with particular attention to enzymuria. Renal damage induced in male Wistar rats by single sc injections of potassium dichromate was assessed 52 to 72 hr after doses ranging from 3 to 20 mg potassium dichromate/kg body weight and throughout a 9-day period following a dose of 20 mg potassium dichromate/kg. The earliest and most sensitive non-invasive functional change in the dose-response and time-response studies was an elevation in the rate of urinary excretion of protein. Evidence of tissue damage was observed with elevations in the urinary excretion rates of the brush border enzymes, gamma-glutamyltransferase, alkaline phosphatase and leucine aminopeptidase, the cytosolic enzymes, aspartate aminotransferase and lactate dehydrogenase and the lysosomal enzyme, N-acetyl-beta-D-glucosaminidase. Such changes occurred as early as the abnormal urinary protein excretion, but returned to control or sub-control values sooner. Urinary brush border enzyme excretion returned to control values within 48 hr following potassium dichromate injection, despite histological and histochemical evidence of extensive renal damage and renal dysfunction. Elevations in plasma aspartate aminotransferase and lactate dehydrogenase levels were observed, but histochemical and isoenzyme studies would be needed to determine the source of these increases. The simplest and most persistent indicators of renal damage were the urinary excretion of protein and N-acetyl-beta-D-glucosaminidase."
1234817,Miller et al. 1988,Characterization of DNA-protein complexes induced in intact cells by the carcinogen chromate,"Potassium chromate induced the formation of DNA-protein complexes in cultured Chinese hamster ovary cells. The DNA-protein complexes were isolated by ultracentrifugal sedimentation in the presence of 2% sodium dodecyl sulfate (SDS) and 5 M urea. Two-dimensional SDS-polyacrylamide gel electrophoresis analysis of the chromate-induced DNA-protein complexes revealed that two acidic proteins of 53 and 45 kDa and a basic protein of 54 kDa were selectively complexed to the DNA. Numerous other proteins also became associated with the DNA to a lesser degree as the chromate concentration was increased. Nuclease digestion was not a prerequisite for the resolution of the protein component of the DNA-protein complexes using two-dimensional gel electrophoresis. Ultracentrifugal analysis of the DNA-protein complexes in the presence of proteinase K, nucleases, or a chelating agent demonstrated that protein aggregation was not responsible for the increased protein recovery in chromate-treated samples and that the complexes were disrupted by EDTA. These data suggest that the selectively complexed proteins were associated with the DNA through strong interactions that may be mediated by the trivalent form of chromium.","Characterization of DNA-protein complexes induced in intact cells by the carcinogen chromate Abs: Potassium chromate induced the formation of DNA-protein complexes in cultured Chinese hamster ovary cells. The DNA-protein complexes were isolated by ultracentrifugal sedimentation in the presence of 2% sodium dodecyl sulfate (SDS) and 5 M urea. Two-dimensional SDS-polyacrylamide gel electrophoresis analysis of the chromate-induced DNA-protein complexes revealed that two acidic proteins of 53 and 45 kDa and a basic protein of 54 kDa were selectively complexed to the DNA. Numerous other proteins also became associated with the DNA to a lesser degree as the chromate concentration was increased. Nuclease digestion was not a prerequisite for the resolution of the protein component of the DNA-protein complexes using two-dimensional gel electrophoresis. Ultracentrifugal analysis of the DNA-protein complexes in the presence of proteinase K, nucleases, or a chelating agent demonstrated that protein aggregation was not responsible for the increased protein recovery in chromate-treated samples and that the complexes were disrupted by EDTA. These data suggest that the selectively complexed proteins were associated with the DNA through strong interactions that may be mediated by the trivalent form of chromium."
1234816,Saloga et al. 1988,Ultrastructural cytochemical visualization of chromium in the skin of sensitized guinea pigs,"Using a modified sulfide silver method for electron microscopy, the intraepidermal and intracellular localization of epicutaneously applied potassium dichromate was investigated at varying times in sensitized and nonsensitized guinea pigs. The hapten penetrated rapidly into the epidermis. There was a homogeneous extra- and intracellular staining of the keratinocytes in the upper epidermis. The basal and suprabasal cells, by contrast, exhibited a predominant extracellular and plasma membrane localization of the silver grains. This membrane staining pattern was also observed in the Langerhans cells showing cellular and endocytotic activation in the sensitized animals. No specific cellular uptake of the hapten by the Langerhans cells was found. These results demonstrate that the epicutaneous application of chromate resulted in a characteristic intraepidermal distribution which may be related to the epidermal conversion of the hexavalent chromate to the immunogenic trivalent form. Moreover, the absent intracellular localization of the hapten in the activated Langerhans cells supports the notion that contact allergens can be presented to T cells without prior intracellular processing.","Ultrastructural cytochemical visualization of chromium in the skin of sensitized guinea pigs Abs: Using a modified sulfide silver method for electron microscopy, the intraepidermal and intracellular localization of epicutaneously applied potassium dichromate was investigated at varying times in sensitized and nonsensitized guinea pigs. The hapten penetrated rapidly into the epidermis. There was a homogeneous extra- and intracellular staining of the keratinocytes in the upper epidermis. The basal and suprabasal cells, by contrast, exhibited a predominant extracellular and plasma membrane localization of the silver grains. This membrane staining pattern was also observed in the Langerhans cells showing cellular and endocytotic activation in the sensitized animals. No specific cellular uptake of the hapten by the Langerhans cells was found. These results demonstrate that the epicutaneous application of chromate resulted in a characteristic intraepidermal distribution which may be related to the epidermal conversion of the hexavalent chromate to the immunogenic trivalent form. Moreover, the absent intracellular localization of the hapten in the activated Langerhans cells supports the notion that contact allergens can be presented to T cells without prior intracellular processing."
1234813,de Raat and  Bakker 1988,Induction of sister chromatid exchanges in Chinese hamster ovary cells by fume particles from various welding processes,BIOSIS COPYRIGHT: BIOL ABS. RRM MUTAGEN OCCUPATIONAL TOXICOLOGY HAZARDOUS MATERIALS STEEL NICKEL CHROMIUM,Induction of sister chromatid exchanges in Chinese hamster ovary cells by fume particles from various welding processes Abs: BIOSIS COPYRIGHT: BIOL ABS. RRM MUTAGEN OCCUPATIONAL TOXICOLOGY HAZARDOUS MATERIALS STEEL NICKEL CHROMIUM
1234812,Sastry et al. 1988,Spectrophotometric determination of some antiamoebic and anthelmintic drugs with metol and chromium(VI),"A sensitive spectrophotometric method is reported for the determination of tinidazole (TZ), metronidazole (MZ), benzoyl metronidazole (BMZ) or niclosamide (NS) either in pure form or in formulations. This method is based on reduction with zinc dust and hydrochloric acid followed by reaction with metol and potassium dichromate at pH 3.0 +/- 0.2 to give a coloured product having maximum absorbance at 720 nm (for TZ, MZ and BMZ) or 530 nm (for NS).","Spectrophotometric determination of some antiamoebic and anthelmintic drugs with metol and chromium(VI) Abs: A sensitive spectrophotometric method is reported for the determination of tinidazole (TZ), metronidazole (MZ), benzoyl metronidazole (BMZ) or niclosamide (NS) either in pure form or in formulations. This method is based on reduction with zinc dust and hydrochloric acid followed by reaction with metol and potassium dichromate at pH 3.0 +/- 0.2 to give a coloured product having maximum absorbance at 720 nm (for TZ, MZ and BMZ) or 530 nm (for NS)."
1234811,Costa et al. 1988,Mutagenicity of lead chromate in Drosophila melanogaster in the presence of nitrilotriacetic acid (NTA),"By using the sex-linked recessive lethal mutation test in Drosophila melanogaster (standard Basc scheme) we analysed the mutagenic effects of treatments by feeding with nitrilotriacetic acid (NTA: 5 X 10(-2) M), with the insoluble Cr(VI) compound lead chromate, PbCrO4 (supernatant of 4.6 X 10(-4)-M suspension in which the actual concentration was 0.06 gamma/ml as Cr(VI)) and with both compounds preincubated at 3 relative ratios (NTA: 5 X 10(-2) M; PbCrO4: 4.6 X 10(-4), 4.6 X 10(-5) and 9.2 X 10(-6) M, respectively). The estimation of mutation frequencies was done at different developmental stages of the germ cells, namely spermatozoa, spermatids and spermatocytes. Ethyl methanesulphonate (EMS: 5 X 10(-3) M) was used as the reference positive control, with clearly mutagenic results. Treatments with NTA or with PbCrO4 alone did not induce any significant increase of the mutation frequency. PbCrO4 at the 3 concentrations tested was completely soluble in the 5 X 10(-2)-M NTA solution, and the mixture of NTA and PbCrO4 induced significant increases of the frequency of sex-linked lethal mutations, with a significant dose-effect relationship with respect to PbCrO4, apparently as a result of the interaction of the compounds and subsequent release of the genotoxic heavy-metal Cr(VI) ions. This result indicates an important synergistic action of NTA with PbCrO4 under the conditions described.","Mutagenicity of lead chromate in Drosophila melanogaster in the presence of nitrilotriacetic acid (NTA) Abs: By using the sex-linked recessive lethal mutation test in Drosophila melanogaster (standard Basc scheme) we analysed the mutagenic effects of treatments by feeding with nitrilotriacetic acid (NTA: 5 X 10(-2) M), with the insoluble Cr(VI) compound lead chromate, PbCrO4 (supernatant of 4.6 X 10(-4)-M suspension in which the actual concentration was 0.06 gamma/ml as Cr(VI)) and with both compounds preincubated at 3 relative ratios (NTA: 5 X 10(-2) M; PbCrO4: 4.6 X 10(-4), 4.6 X 10(-5) and 9.2 X 10(-6) M, respectively). The estimation of mutation frequencies was done at different developmental stages of the germ cells, namely spermatozoa, spermatids and spermatocytes. Ethyl methanesulphonate (EMS: 5 X 10(-3) M) was used as the reference positive control, with clearly mutagenic results. Treatments with NTA or with PbCrO4 alone did not induce any significant increase of the mutation frequency. PbCrO4 at the 3 concentrations tested was completely soluble in the 5 X 10(-2)-M NTA solution, and the mixture of NTA and PbCrO4 induced significant increases of the frequency of sex-linked lethal mutations, with a significant dose-effect relationship with respect to PbCrO4, apparently as a result of the interaction of the compounds and subsequent release of the genotoxic heavy-metal Cr(VI) ions. This result indicates an important synergistic action of NTA with PbCrO4 under the conditions described."
1234809,Gollhausen et al. 1988,Trends in allergic contact sensitization,"A standard patch test series was tested for 7 years (1977-1983) in a total of 11,962 patients. The annual frequency of positive reactions to the compounds tested was assessed for the total and for males and females separately. During the observation period, there were significant increases in positive reactions in the total group from 6.2% to 12.7% for nickel sulphate, from 5.3% to 7.0% for balsam of Peru and from 3.8% to 6.5% for potassium dichromate, reflecting significant changes in both sexes. The frequency of positive reactions to wool alcohols, formaldehyde, neomycin sulphate, paraben mix and gentamycin sulphate significantly increased, while that of positive reactions to clioquinol, mercuric chloride and turpentine peroxide significantly decreased in either males or females, sometimes leading to significant changes in the total group.","Trends in allergic contact sensitization Abs: A standard patch test series was tested for 7 years (1977-1983) in a total of 11,962 patients. The annual frequency of positive reactions to the compounds tested was assessed for the total and for males and females separately. During the observation period, there were significant increases in positive reactions in the total group from 6.2% to 12.7% for nickel sulphate, from 5.3% to 7.0% for balsam of Peru and from 3.8% to 6.5% for potassium dichromate, reflecting significant changes in both sexes. The frequency of positive reactions to wool alcohols, formaldehyde, neomycin sulphate, paraben mix and gentamycin sulphate significantly increased, while that of positive reactions to clioquinol, mercuric chloride and turpentine peroxide significantly decreased in either males or females, sometimes leading to significant changes in the total group."
1234808,Hostynek and  Maibach 1988,Chromium in US household bleach,Spectrophotometric analysis for chromium in hypochlorite bleach sampled at random throughout the USA shows that the highest level found in those products is of the order of 0.1 ppm (2/20). This probably does not represent a significant risk factor for chromate sensitization of the consumer population.,Chromium in US household bleach Abs: Spectrophotometric analysis for chromium in hypochlorite bleach sampled at random throughout the USA shows that the highest level found in those products is of the order of 0.1 ppm (2/20). This probably does not represent a significant risk factor for chromate sensitization of the consumer population.
1234807,Susa et al. 1988,"Effect of combined administration of DL-penicillamine and potassium dichromate on lethality, distribution and excretion of chromium in mice",,"Effect of combined administration of DL-penicillamine and potassium dichromate on lethality, distribution and excretion of chromium in mice Abs: "
1234805,Fransway and  Winkelmann 1988,Chronic dermatitis evolving to mycosis fungoides: report of four cases and review of the literature,"In four patients with long-standing chronic dermatitis, evolution into cutaneous T-cell lymphoma was observed. Two patients were men and two were women; they were aged forty-nine to sixty-five years at first presentation. Duration of dermatitis at admission was from two months to fifteen years, with the clinical and histologic diagnosis documented on initial examination. After another five to nine years, clinically and histologically verified mycosis fungoides occurred. In two patients, contact factors were verified as causative by results of patch testing; sensitivities documented included nickel, potassium dichromate, and formaldehyde. In a third patient, contact factors were implicated as causes, but patch testing was not performed. We propose that certain instances of cutaneous T-cell lymphoma may be caused by chronic antigenic immunostimulation with resultant malignant lymphocyte clonality.","Chronic dermatitis evolving to mycosis fungoides: report of four cases and review of the literature Abs: In four patients with long-standing chronic dermatitis, evolution into cutaneous T-cell lymphoma was observed. Two patients were men and two were women; they were aged forty-nine to sixty-five years at first presentation. Duration of dermatitis at admission was from two months to fifteen years, with the clinical and histologic diagnosis documented on initial examination. After another five to nine years, clinically and histologically verified mycosis fungoides occurred. In two patients, contact factors were verified as causative by results of patch testing; sensitivities documented included nickel, potassium dichromate, and formaldehyde. In a third patient, contact factors were implicated as causes, but patch testing was not performed. We propose that certain instances of cutaneous T-cell lymphoma may be caused by chronic antigenic immunostimulation with resultant malignant lymphocyte clonality."
1234804,Goh 1988,An epidemiological comparison between hand eczema and non-hand eczema,"Thirty four per cent of 2110 patients with eczema attending a contact dermatitis clinic presented with hand eczema. An epidemiological comparison was made of patients with hand eczema and non-hand eczema (defined as eczema on parts of the body other than the hands). Occupational eczema was significantly more common in the hand eczema than the non-hand eczema group (P = 0.0011). The prevalence of atopy was the same in both groups (13%). The prevalence of irritant contact dermatitis was higher in the hand eczema group (32%) than the non-hand eczema group (13%) (P less than 0.0001). The rate of allergic contact dermatitis was lower in the hand eczema group (23%) than the non-hand eczema group (39%) (P less than 0.0001). The rate of positive patch test reactions was lower in the hand eczema group (41%) than the non-hand eczema group (56%) (P less than 0.0001). Nickel sulphate (8%), cobalt chloride (3%), potassium dichromate (3%), and fragrance mix (4%) were common allergens encountered in hand eczema group. None of these allergens was specifically more prevalent in the hand eczema than the non-hand eczema group. However, the prevalence of allergy to nickel, colophony, epoxy resin and medicaments was significantly higher in the non-hand eczema group.","An epidemiological comparison between hand eczema and non-hand eczema Abs: Thirty four per cent of 2110 patients with eczema attending a contact dermatitis clinic presented with hand eczema. An epidemiological comparison was made of patients with hand eczema and non-hand eczema (defined as eczema on parts of the body other than the hands). Occupational eczema was significantly more common in the hand eczema than the non-hand eczema group (P = 0.0011). The prevalence of atopy was the same in both groups (13%). The prevalence of irritant contact dermatitis was higher in the hand eczema group (32%) than the non-hand eczema group (13%) (P less than 0.0001). The rate of allergic contact dermatitis was lower in the hand eczema group (23%) than the non-hand eczema group (39%) (P less than 0.0001). The rate of positive patch test reactions was lower in the hand eczema group (41%) than the non-hand eczema group (56%) (P less than 0.0001). Nickel sulphate (8%), cobalt chloride (3%), potassium dichromate (3%), and fragrance mix (4%) were common allergens encountered in hand eczema group. None of these allergens was specifically more prevalent in the hand eczema than the non-hand eczema group. However, the prevalence of allergy to nickel, colophony, epoxy resin and medicaments was significantly higher in the non-hand eczema group."
1234802,Keinonen and  Salminen 1988,Influence of some development parameters on the reflection grating structure in dichromated gelatin,"We made reflection gratings by using the gelatin of Kodak 649F spectroscopic plates. The concentration of ammonium dichromate sensitizer was varied, and reflection efficiencies of fully developed plates were measured in different reconstructing angles. During the development process we varied the washing time, the time interval between the washing and isopropanol baths, and the duration of the isopropanol bath. The reflection efficiencies were measured for each processing variable. Finally, the characteristics of the gratings were tested by varying the recording geometry.","Influence of some development parameters on the reflection grating structure in dichromated gelatin Abs: We made reflection gratings by using the gelatin of Kodak 649F spectroscopic plates. The concentration of ammonium dichromate sensitizer was varied, and reflection efficiencies of fully developed plates were measured in different reconstructing angles. During the development process we varied the washing time, the time interval between the washing and isopropanol baths, and the duration of the isopropanol bath. The reflection efficiencies were measured for each processing variable. Finally, the characteristics of the gratings were tested by varying the recording geometry."
1234800,Smith 1988,The use of renal cortical slices from the Fischer 344 rat as an in vitro model to evaluate nephrotoxicity,"The toxicity of several classical acute nephrotoxicants was evaluated in an in vitro system using renal cortical slices prepared from adult male Fischer 344 rats. Gentamicin, cephaloridine, 4-ipomeanol, potassium dichromate (K2Cr2O7), mercuric chloride (HgCl2), carbon tetrachloride (CCl4), and hexachlorobutadiene (HCBD) were preincubated with slices for 2 hr at 37 degrees C at concentrations ranging from 1 x 10(-6) to 1 x 10(-1) M. Following preincubation, slices were removed, rinsed in medium lacking the nephrotoxicant, and subsequently incubated for 90 min at 25 degrees C for physiological assessment of proximal tubular functions. Using a single preparation, slices were monitored for organic ion accumulation, gluconeogenesis, lipid peroxidation, and total glutathione (reduced and oxidized) concentrations. In addition, preincubation and incubation media were assessed for the presence of renal enzymes originating from brush border, cytosol, and lysosomes. The relative degree of toxicity in this model was consistent with nephrotoxic potency in vivo where HgCl2, K2Cr2O7 greater than HCBD greater than CCl4, cephaloridine greater than gentamicin greater than 4-ipomeanol. Effects on organic ion accumulation, gluconeogenesis, and glutathione concentrations occurred simultaneously for each toxicant. Toxicants produced different effects on enzyme release and malondialdehyde formation. These results suggest that toxicity produced in vitro is representative of in vivo nephrotoxicity and support the further use of this model to evaluate mechanisms of nephrotoxicity.","The use of renal cortical slices from the Fischer 344 rat as an in vitro model to evaluate nephrotoxicity Abs: The toxicity of several classical acute nephrotoxicants was evaluated in an in vitro system using renal cortical slices prepared from adult male Fischer 344 rats. Gentamicin, cephaloridine, 4-ipomeanol, potassium dichromate (K2Cr2O7), mercuric chloride (HgCl2), carbon tetrachloride (CCl4), and hexachlorobutadiene (HCBD) were preincubated with slices for 2 hr at 37 degrees C at concentrations ranging from 1 x 10(-6) to 1 x 10(-1) M. Following preincubation, slices were removed, rinsed in medium lacking the nephrotoxicant, and subsequently incubated for 90 min at 25 degrees C for physiological assessment of proximal tubular functions. Using a single preparation, slices were monitored for organic ion accumulation, gluconeogenesis, lipid peroxidation, and total glutathione (reduced and oxidized) concentrations. In addition, preincubation and incubation media were assessed for the presence of renal enzymes originating from brush border, cytosol, and lysosomes. The relative degree of toxicity in this model was consistent with nephrotoxic potency in vivo where HgCl2, K2Cr2O7 greater than HCBD greater than CCl4, cephaloridine greater than gentamicin greater than 4-ipomeanol. Effects on organic ion accumulation, gluconeogenesis, and glutathione concentrations occurred simultaneously for each toxicant. Toxicants produced different effects on enzyme release and malondialdehyde formation. These results suggest that toxicity produced in vitro is representative of in vivo nephrotoxicity and support the further use of this model to evaluate mechanisms of nephrotoxicity."
1234799,Hogan et al. 1988,"Results of routine patch testing of 542 patients in Saskatoon, Canada","542 patients (330 women, 212 men) with suspected allergic contact dermatitis were patch tested to standard series allergens between January 1983 and June 1987. Positive reactions were most frequently seen with nickel (17.4%), ethylenediamine (8.7%), formaldehyde (7.4%), colophony (7.0%), potassium dichromate (6.1%) and neomycin (5.7%). Patients with dermatitis involving the legs were significantly more likely to be allergic to ethylenediamine (p = 0.01) and benzocaine (p = 0.04) than those with dermatitis not involving the legs. Neomycin allergy was not associated with dermatitis involving the legs. Patients allergic to ethylenediamine were significantly more likely to be allergic to neomycin than patients not allergic to ethylenediamine (p = 0.002).","Results of routine patch testing of 542 patients in Saskatoon, Canada Abs: 542 patients (330 women, 212 men) with suspected allergic contact dermatitis were patch tested to standard series allergens between January 1983 and June 1987. Positive reactions were most frequently seen with nickel (17.4%), ethylenediamine (8.7%), formaldehyde (7.4%), colophony (7.0%), potassium dichromate (6.1%) and neomycin (5.7%). Patients with dermatitis involving the legs were significantly more likely to be allergic to ethylenediamine (p = 0.01) and benzocaine (p = 0.04) than those with dermatitis not involving the legs. Neomycin allergy was not associated with dermatitis involving the legs. Patients allergic to ethylenediamine were significantly more likely to be allergic to neomycin than patients not allergic to ethylenediamine (p = 0.002)."
1234798,Lang and  Iba 1988,"Metabolism of 3,3'-dichlorobenzidine by horseradish peroxidase","1. The peroxidatic oxidation of 3,3'-dichlorobenzidine by horseradish peroxidase in the presence of H2O2 was examined spectrophotometrically and the reactivity of the spectral species were compared to those formed from the peroxidative oxidation of benzidine. 2. The horseradish peroxidase-catalyzed oxidation of 3,3'-dichlorobenzidine yielded two transient and one stable spectral species with absorption maxima at 630 nm, 370 nm and 410 nm, respectively, whereas that of benzidine yielded three stable spectral species with absorption maxima at 610 nm, 425 nm and 370 nm, respectively. 3. The 425 nm species from benzidine, but not the 410 nm species from 3,3'-dichlorobenzidine was scavenged by butylated hydroxyanisole, glutathione, N-acetylcysteine or 2-deoxyguanosine. 4. H.p.l.c. mass spectrometric analysis, and comparative studies with potassium dichromate oxidation of 3,3'-dichlorobenzidine, indicated that the major product from the horseradish peroxidase-catalyzed oxidation of 3,3'-dichlorobenzidine is azo-3,3'-dichlorobenzidine. 5. None of the products from enzymic or chemical oxidation of either 3,3'-dichlorobenzidine or benzidine was directly mutagenic to S. typhimurium TA98 in the Ames test; however the chemically oxidized and enzymic products from 3,3'-dichlorobenzidine were mutagenic in the presence of H2O2. 6. The data indicate that despite apparent structural similarities between the intermediates formed during the peroxidatic oxidation of all benzidines, the intermediates and products of peroxidatic oxidation of dichlorobenzidine have reactivities and stabilities different from those of other benzidines.","Metabolism of 3,3'-dichlorobenzidine by horseradish peroxidase Abs: 1. The peroxidatic oxidation of 3,3'-dichlorobenzidine by horseradish peroxidase in the presence of H2O2 was examined spectrophotometrically and the reactivity of the spectral species were compared to those formed from the peroxidative oxidation of benzidine. 2. The horseradish peroxidase-catalyzed oxidation of 3,3'-dichlorobenzidine yielded two transient and one stable spectral species with absorption maxima at 630 nm, 370 nm and 410 nm, respectively, whereas that of benzidine yielded three stable spectral species with absorption maxima at 610 nm, 425 nm and 370 nm, respectively. 3. The 425 nm species from benzidine, but not the 410 nm species from 3,3'-dichlorobenzidine was scavenged by butylated hydroxyanisole, glutathione, N-acetylcysteine or 2-deoxyguanosine. 4. H.p.l.c. mass spectrometric analysis, and comparative studies with potassium dichromate oxidation of 3,3'-dichlorobenzidine, indicated that the major product from the horseradish peroxidase-catalyzed oxidation of 3,3'-dichlorobenzidine is azo-3,3'-dichlorobenzidine. 5. None of the products from enzymic or chemical oxidation of either 3,3'-dichlorobenzidine or benzidine was directly mutagenic to S. typhimurium TA98 in the Ames test; however the chemically oxidized and enzymic products from 3,3'-dichlorobenzidine were mutagenic in the presence of H2O2. 6. The data indicate that despite apparent structural similarities between the intermediates formed during the peroxidatic oxidation of all benzidines, the intermediates and products of peroxidatic oxidation of dichlorobenzidine have reactivities and stabilities different from those of other benzidines."
1234797,Herzog et al. 1988,Milk tester's dermatitis,"Hand dermatitis is a frequent problem among workers in milk testing laboratories. An epidemiologic study was conducted at the Pennsylvania Dairy Herd Improvement Association Milk Testing Laboratory, where more than 300,000 milk samples are examined monthly for protein, butterfat, and &quot;somatic&quot; cells. These samples are preserved with potassium dichromate for transport from the farm to the laboratory. A survey of the laboratory was conducted and workers were interviewed. Eight of 16 subjects reported a history of occupationally exacerbated hand dermatitis. Three of 16 subjects had positive patch test results to potassium dichromate. Two of 15 subjects who underwent patch testing to milk preserved with potassium dichromate had positive reactions. None reacted to milk alone, bronopol, or Kathon CG. Two workers are receiving workers' compensation because of severe allergic contact dermatitis of the hands to potassium dichromate. We conclude that milk testing laboratory workers are at substantial risk for acquiring allergic contact dermatitis from milk preserved with potassium dichromate.","Milk tester's dermatitis Abs: Hand dermatitis is a frequent problem among workers in milk testing laboratories. An epidemiologic study was conducted at the Pennsylvania Dairy Herd Improvement Association Milk Testing Laboratory, where more than 300,000 milk samples are examined monthly for protein, butterfat, and &quot;somatic&quot; cells. These samples are preserved with potassium dichromate for transport from the farm to the laboratory. A survey of the laboratory was conducted and workers were interviewed. Eight of 16 subjects reported a history of occupationally exacerbated hand dermatitis. Three of 16 subjects had positive patch test results to potassium dichromate. Two of 15 subjects who underwent patch testing to milk preserved with potassium dichromate had positive reactions. None reacted to milk alone, bronopol, or Kathon CG. Two workers are receiving workers' compensation because of severe allergic contact dermatitis of the hands to potassium dichromate. We conclude that milk testing laboratory workers are at substantial risk for acquiring allergic contact dermatitis from milk preserved with potassium dichromate."
1234794,Arillo and  Melodia 1988,Effects of hexavalent chromium on trout mitochondria,Trout liver mitochondria were incubated in the presence of micromolar concentration of potassium dichromate (Cr(VI)) under several experimental conditions. Cr(VI) strongly inhibited both state 3 and state 4 of respiration supplemented by NAD-linked substrates; it also slightly affected the respiration of FAD-linked substrates. Evidence is provided that the respiratory inhibition induced by dichromate is partially coupled to the Cr(VI) reduction mechanism occurring in mitochondria.,Effects of hexavalent chromium on trout mitochondria Abs: Trout liver mitochondria were incubated in the presence of micromolar concentration of potassium dichromate (Cr(VI)) under several experimental conditions. Cr(VI) strongly inhibited both state 3 and state 4 of respiration supplemented by NAD-linked substrates; it also slightly affected the respiration of FAD-linked substrates. Evidence is provided that the respiratory inhibition induced by dichromate is partially coupled to the Cr(VI) reduction mechanism occurring in mitochondria.
1234793,Serrano et al. 1988,A comparison of a microdiffusion method for ethanol and the Abbott TDx ethanol assay,"A simple, rapid ethanol screen based on a microdiffusion technique (Analytical Systems, Marion Laboratories) has been evaluated and compared to an established enzymatic procedure (Abbott TDx). They showed agreement in 484 of 488 biological specimens and all control specimens. They disagreed on 4 specimens--3 positive by the Marion method and negative by TDx, and 1 positive by TDx and negative by Marion. The discrepancies could not be elucidated because insufficient quantities of samples remained. The microdiffusion method was found to be a dependable, reproducible screening test for the presence of reducing volatiles in urine. There is insufficient data to evaluate its effectiveness in serum or whole blood. It is particularly suited for screening negative specimens before quantitating positive specimens by a suitable alternate quantitative method.","A comparison of a microdiffusion method for ethanol and the Abbott TDx ethanol assay Abs: A simple, rapid ethanol screen based on a microdiffusion technique (Analytical Systems, Marion Laboratories) has been evaluated and compared to an established enzymatic procedure (Abbott TDx). They showed agreement in 484 of 488 biological specimens and all control specimens. They disagreed on 4 specimens--3 positive by the Marion method and negative by TDx, and 1 positive by TDx and negative by Marion. The discrepancies could not be elucidated because insufficient quantities of samples remained. The microdiffusion method was found to be a dependable, reproducible screening test for the presence of reducing volatiles in urine. There is insufficient data to evaluate its effectiveness in serum or whole blood. It is particularly suited for screening negative specimens before quantitating positive specimens by a suitable alternate quantitative method."
1234789,Fortunati and  Bianchi 1989,Plasma membrane damage detected by nucleic acid leakage,"Among the indicators of membrane damage, the leakage of intracellular components into the medium is the most directly related to the perturbations of the membrane molecular organization. The extent of the damage can be evaluated from the size of the released components. We have designed a protocol for the detection of membrane leakage based on the preincubation of cells with tritiated adenine for 24 h, followed by a 24-h chase in nonradioactive medium. The treatment takes place when the distribution of the precursor among its end products has reached the plateau, and thus the differences of radioactivity in the fractions obtained from the control and treated cultures (medium, nucleotide pool, RNA, DNA) correspond to actual quantitative variations induced by the test chemical. Aliquots of the medium are processed to determine which percentage of the released material is macromolecular, in order to distinguish between mild and severe membrane damage. The origin of the extracellular radioactivity can be recognized from the variations of RNA counts in the treated cells. DNA radioactivity is used to evaluate the number of cells that remain attached to the plates in the different conditions of treatment. By this means, generalized permeabilization of membranes to macromolecules is distinguished from complete solubilization of only a subpopulation of cells. We present some examples of application of the protocol with detergents (LAS, SDS, Triton X-100) and with Cr(VI), which damages cell membranes by a different mechanism of action.","Plasma membrane damage detected by nucleic acid leakage Abs: Among the indicators of membrane damage, the leakage of intracellular components into the medium is the most directly related to the perturbations of the membrane molecular organization. The extent of the damage can be evaluated from the size of the released components. We have designed a protocol for the detection of membrane leakage based on the preincubation of cells with tritiated adenine for 24 h, followed by a 24-h chase in nonradioactive medium. The treatment takes place when the distribution of the precursor among its end products has reached the plateau, and thus the differences of radioactivity in the fractions obtained from the control and treated cultures (medium, nucleotide pool, RNA, DNA) correspond to actual quantitative variations induced by the test chemical. Aliquots of the medium are processed to determine which percentage of the released material is macromolecular, in order to distinguish between mild and severe membrane damage. The origin of the extracellular radioactivity can be recognized from the variations of RNA counts in the treated cells. DNA radioactivity is used to evaluate the number of cells that remain attached to the plates in the different conditions of treatment. By this means, generalized permeabilization of membranes to macromolecules is distinguished from complete solubilization of only a subpopulation of cells. We present some examples of application of the protocol with detergents (LAS, SDS, Triton X-100) and with Cr(VI), which damages cell membranes by a different mechanism of action."
1234788,Venier et al. 1989,Induction of SOS response in Escherichia coli strain PQ37 by 16 chemical compounds and human urine extracts,"The SOS Chromotest on Escherichia coli strain PQ37 was used to detect DNA damage induced by 16 chemical compounds and urine samples from smokers and a non-smoking psoriatic patient treated with mineral coal tar. The results confirmed the strong SOS inducing activity of 2-aminoanthracene and benzo[a]pyrene with metabolic activation and N-methyl-N'-nitro-N-nitrosoguanidine, mitomycin C and 4-nitroquinoline-N-oxide without metabolic activation. A weaker response in the absence of microsomal enzymes was observed with hydroxyurea (only at high doses) and the soluble Cr(VI) compounds potassium chromate and potassium dichromate. No effect was observed with ampicillin, cadmium chloride, cyclophosphamide, griseofulvin, the insoluble Cr(VI) compound lead chromate, the soluble Cr(III) compounds chromium nitrate, chromium chloride, chromium potassium sulphate, and the chelating agent sodium nitrilotriacetate. Among the Cr(III) compounds only chromium acetate produced a low but significant increase of SOS inducing activity. Solubilization by nitrilotriacetate of genotoxic Cr(VI) from insoluble lead chromate was observed, whereas no interaction occurred between nitrilotriacetate and the soluble Cr(VI) and Cr(III) compounds. Using urinary XAD-2 extracts, we found the SOS Chromotest poorly sensitive to the mutagens present in urine from tobacco smokers which, on the other hand, were detected by the gene mutation assay in Salmonella typhimurium (Ames test). A urine sample obtained from a psoriatic patient, therapeutically treated with mineral coal tar, had a significant SOS inducing activity with and even without metabolic activation, whereas in the Ames test it was active only in the presence of metabolic activation.(ABSTRACT TRUNCATED AT 250 WORDS)","Induction of SOS response in Escherichia coli strain PQ37 by 16 chemical compounds and human urine extracts Abs: The SOS Chromotest on Escherichia coli strain PQ37 was used to detect DNA damage induced by 16 chemical compounds and urine samples from smokers and a non-smoking psoriatic patient treated with mineral coal tar. The results confirmed the strong SOS inducing activity of 2-aminoanthracene and benzo[a]pyrene with metabolic activation and N-methyl-N'-nitro-N-nitrosoguanidine, mitomycin C and 4-nitroquinoline-N-oxide without metabolic activation. A weaker response in the absence of microsomal enzymes was observed with hydroxyurea (only at high doses) and the soluble Cr(VI) compounds potassium chromate and potassium dichromate. No effect was observed with ampicillin, cadmium chloride, cyclophosphamide, griseofulvin, the insoluble Cr(VI) compound lead chromate, the soluble Cr(III) compounds chromium nitrate, chromium chloride, chromium potassium sulphate, and the chelating agent sodium nitrilotriacetate. Among the Cr(III) compounds only chromium acetate produced a low but significant increase of SOS inducing activity. Solubilization by nitrilotriacetate of genotoxic Cr(VI) from insoluble lead chromate was observed, whereas no interaction occurred between nitrilotriacetate and the soluble Cr(VI) and Cr(III) compounds. Using urinary XAD-2 extracts, we found the SOS Chromotest poorly sensitive to the mutagens present in urine from tobacco smokers which, on the other hand, were detected by the gene mutation assay in Salmonella typhimurium (Ames test). A urine sample obtained from a psoriatic patient, therapeutically treated with mineral coal tar, had a significant SOS inducing activity with and even without metabolic activation, whereas in the Ames test it was active only in the presence of metabolic activation.(ABSTRACT TRUNCATED AT 250 WORDS)"
1234786,Goh 1989,An epidemiological comparison between occupational and non-occupational hand eczema,"Thirty-four per cent of 2110 patients with eczema attending a contact dermatitis clinic had hand eczema. Fifty-five per cent (395 of 721) had contact dermatitis and 45% (326 of 721) had endogenous/unclassifiable eczema. Thirty-five per cent of cases (217 of 721) were occupational eczema. An epidemiological comparison of patients with occupational and non-occupational hand eczema (defined as eczema occurring on the hands up to the wrist line) was made. Hand eczema was more common in males in both groups, and there was a significantly larger proportion of males in the occupational group (65%) than the non-occupational group (51%) (P less than 0.001). The prevalence of a personal or family history of atopy was significantly lower in the occupational group (7%) than the non-occupational group (15%) (P less than 0.005). Irritant contact dermatitis occurred in a larger proportion of patients in the occupational group (76%) than the non-occupational group (39%) (P less than 0.0001). There was no significant difference between the proportions of patients with positive patch test reactions in the occupational group (34%) and the non-occupational group (41%). Potassium dichromate, and epoxy resin allergy occurred significantly, more frequently, in the occupational group whereas fragrance-mix allergy was significantly more frequent in the non-occupational group.","An epidemiological comparison between occupational and non-occupational hand eczema Abs: Thirty-four per cent of 2110 patients with eczema attending a contact dermatitis clinic had hand eczema. Fifty-five per cent (395 of 721) had contact dermatitis and 45% (326 of 721) had endogenous/unclassifiable eczema. Thirty-five per cent of cases (217 of 721) were occupational eczema. An epidemiological comparison of patients with occupational and non-occupational hand eczema (defined as eczema occurring on the hands up to the wrist line) was made. Hand eczema was more common in males in both groups, and there was a significantly larger proportion of males in the occupational group (65%) than the non-occupational group (51%) (P less than 0.001). The prevalence of a personal or family history of atopy was significantly lower in the occupational group (7%) than the non-occupational group (15%) (P less than 0.005). Irritant contact dermatitis occurred in a larger proportion of patients in the occupational group (76%) than the non-occupational group (39%) (P less than 0.0001). There was no significant difference between the proportions of patients with positive patch test reactions in the occupational group (34%) and the non-occupational group (41%). Potassium dichromate, and epoxy resin allergy occurred significantly, more frequently, in the occupational group whereas fragrance-mix allergy was significantly more frequent in the non-occupational group."
1234785,Miller et al. 1989,"Analysis of proteins cross-linked to DNA after treatment of cells with formaldehyde, chromate, and cis-diamminedichloroplatinum(II)","The proteins cross-linked to the DNA of cultured Chinese hamster ovary cells after exposure to cis-diamminedichloroplatinum(II) (cis-Pt), chromate, and formaldehyde were compared by two-dimensional (2D) gel electrophoresis, immunoblotting, and centrifugal assays that measured cross-link stability. Chromate and cis-Pt cross-linked seven of the same nonhistone proteins, such as actin, to DNA. In contrast, formaldehyde selectively formed histone-DNA cross-links. Immunoblotting experiments showed that all three chemicals cross-linked a 97-kDa nuclear protein to the DNA despite their different chemical reactivity with DNA and proteins. The chromate- and cis-Pt-induced cross-links were disrupted by thiourea, 2-mercaptoethanol, and EDTA, indicating that the metal could be chemically displaced from the cross-links. The formaldehyde-induced complexes required degradation with DNase 1 for the resolution of histones on 2D gels and were not chemically labile like the metal-induced cross-links. The agents and methodology used here could be applied to the study of additional nuclear proteins that bind or reside near the DNA.","Analysis of proteins cross-linked to DNA after treatment of cells with formaldehyde, chromate, and cis-diamminedichloroplatinum(II) Abs: The proteins cross-linked to the DNA of cultured Chinese hamster ovary cells after exposure to cis-diamminedichloroplatinum(II) (cis-Pt), chromate, and formaldehyde were compared by two-dimensional (2D) gel electrophoresis, immunoblotting, and centrifugal assays that measured cross-link stability. Chromate and cis-Pt cross-linked seven of the same nonhistone proteins, such as actin, to DNA. In contrast, formaldehyde selectively formed histone-DNA cross-links. Immunoblotting experiments showed that all three chemicals cross-linked a 97-kDa nuclear protein to the DNA despite their different chemical reactivity with DNA and proteins. The chromate- and cis-Pt-induced cross-links were disrupted by thiourea, 2-mercaptoethanol, and EDTA, indicating that the metal could be chemically displaced from the cross-links. The formaldehyde-induced complexes required degradation with DNase 1 for the resolution of histones on 2D gels and were not chemically labile like the metal-induced cross-links. The agents and methodology used here could be applied to the study of additional nuclear proteins that bind or reside near the DNA."
1234783,Spacek 1989,Dynamics of the Golgi method: a time-lapse study of the early stages of impregnation in single sections,"This paper describes the early stages of impregnation by the Golgi method. Sections of aldehyde-fixed and potassium dichromate-treated cerebral cortex were mounted on glass slides and cover slipped. The dichromate solution was replaced by silver nitrate solution and events in the section were followed and recorded by time lapse microphotography and video recording until stopped by replacement of silver nitrate solution by glycerol. The sections were subsequently prepared for electron microscopy (EM) study. In sections about 2 x 2 mm and 100 microns thick a fine, dark granular precipitate formed at the edges within the first minutes of exposure to silver nitrate and a wave of brownish colouration spread to a depth of about 0.3 mm. After approximately 7 min, shrub-like focal precipitates (nucleation centres) appeared in the sections. From these nucleation centres (but also from the section edges) thread-like 'outgrowths', usually identified as dendrites, spread into somata. Sometimes impregnation began within the soma and spread into dendrites. The rate of impregnation (i.e., of silver chromate deposition within dendrites) was typically 1-7 microns min-1, faster in the earlier stages (up to 3 microns s-1) and very slow after 30 min, by which time many neurons were more or less fully impregnated. The dimensions of the section, the width of an agar frame around the sections, and the frequency with which the silver nitrate in the sections was replenished all affected the extent and time course of the impregnation. By EM the earliest intracellular deposits consisted of tubulolamellar formations which did not cross plasma or endocellular membrane boundaries and which contained irregularly shaped and scattered granules, initially about 10 nm in diameter. The latter progressively enlarged and coalesced as the tubulolamellar formations extended, eventually to fill the cross-sectional area of neuronal processes and cell bodies. These observations shed light on why so few neurons become impregnated with the Golgi method. Impregnation occurred only in those cells a part of which was within a nucleation centre.","Dynamics of the Golgi method: a time-lapse study of the early stages of impregnation in single sections Abs: This paper describes the early stages of impregnation by the Golgi method. Sections of aldehyde-fixed and potassium dichromate-treated cerebral cortex were mounted on glass slides and cover slipped. The dichromate solution was replaced by silver nitrate solution and events in the section were followed and recorded by time lapse microphotography and video recording until stopped by replacement of silver nitrate solution by glycerol. The sections were subsequently prepared for electron microscopy (EM) study. In sections about 2 x 2 mm and 100 microns thick a fine, dark granular precipitate formed at the edges within the first minutes of exposure to silver nitrate and a wave of brownish colouration spread to a depth of about 0.3 mm. After approximately 7 min, shrub-like focal precipitates (nucleation centres) appeared in the sections. From these nucleation centres (but also from the section edges) thread-like 'outgrowths', usually identified as dendrites, spread into somata. Sometimes impregnation began within the soma and spread into dendrites. The rate of impregnation (i.e., of silver chromate deposition within dendrites) was typically 1-7 microns min-1, faster in the earlier stages (up to 3 microns s-1) and very slow after 30 min, by which time many neurons were more or less fully impregnated. The dimensions of the section, the width of an agar frame around the sections, and the frequency with which the silver nitrate in the sections was replenished all affected the extent and time course of the impregnation. By EM the earliest intracellular deposits consisted of tubulolamellar formations which did not cross plasma or endocellular membrane boundaries and which contained irregularly shaped and scattered granules, initially about 10 nm in diameter. The latter progressively enlarged and coalesced as the tubulolamellar formations extended, eventually to fill the cross-sectional area of neuronal processes and cell bodies. These observations shed light on why so few neurons become impregnated with the Golgi method. Impregnation occurred only in those cells a part of which was within a nucleation centre."
1234781,Macfarlane et al. 1989,Delayed patch test reactions at days 7 and 9,"403 consecutive patients were examined on days 2, 4, 7, and 9 following application of patch tests. Late positive reactions, i.e., those which manifested after day 4, were seen in 29 patients (7.2%). The allergens which most commonly produced late positive reactions were neomycin (7), potassium dichromate (4), and cobalt (3). Paired patch test readings on days 4 and 7 were more reliable than those on days 2 and 4. If only 1 patch test reading were performed, a single reading on day 4 would have been most useful. The reading on day 9 proved to be of limited value. Of 11 patients who were retested after an interval of more than 6 months, 7 showed earlier eliciting reactions, which may have been due to active sensitization.","Delayed patch test reactions at days 7 and 9 Abs: 403 consecutive patients were examined on days 2, 4, 7, and 9 following application of patch tests. Late positive reactions, i.e., those which manifested after day 4, were seen in 29 patients (7.2%). The allergens which most commonly produced late positive reactions were neomycin (7), potassium dichromate (4), and cobalt (3). Paired patch test readings on days 4 and 7 were more reliable than those on days 2 and 4. If only 1 patch test reading were performed, a single reading on day 4 would have been most useful. The reading on day 9 proved to be of limited value. Of 11 patients who were retested after an interval of more than 6 months, 7 showed earlier eliciting reactions, which may have been due to active sensitization."
1234779,Miller et al. 1989,Immunological detection of DNA-protein complexes induced by chromate,"A select group of non-histone proteins becomes complexed to DNA after Chinese hamster ovary (CHO) cells are treated with potassium chromate. The most abundant complexed protein has a mol. wt of approximately 45 kd and is thought to be actin. An antiserum to the chromate-induced DNA-protein complexes (DPCs) was prepared to facilitate the study of these complexes. Rather than detecting the predominant silver-stained proteins of DPCs described in an earlier study, this antiserum reacts primarily with an acidic 95-kd protein (p95) that does not silver stain. The antiserum can be used routinely to assay for the induction of p95-DNA complexes produced by chromate and perhaps by other carcinogens. Immunofluorescent staining of CHO cells and immunoblotting of cell fractions show the reactive antigens are within the cell nucleus. Blotting experiments with the antiserum indicate the chromate-induced p95-DNA complex dissociates in the presence of 2-mercaptoethanol, suggesting similarity to the DPCs formed by carcinogenic platinum compounds. A reduced species of chromium (probably Cr3+) may form DPCs by binding to the nitrogen, oxygen or sulfur atoms of proteins and DNA. These results illustrate the usefulness of immunological detection methods to study specific DNA-protein interactions induced by carcinogens. The possible relevance of DPCs in the carcinogenic process is discussed.","Immunological detection of DNA-protein complexes induced by chromate Abs: A select group of non-histone proteins becomes complexed to DNA after Chinese hamster ovary (CHO) cells are treated with potassium chromate. The most abundant complexed protein has a mol. wt of approximately 45 kd and is thought to be actin. An antiserum to the chromate-induced DNA-protein complexes (DPCs) was prepared to facilitate the study of these complexes. Rather than detecting the predominant silver-stained proteins of DPCs described in an earlier study, this antiserum reacts primarily with an acidic 95-kd protein (p95) that does not silver stain. The antiserum can be used routinely to assay for the induction of p95-DNA complexes produced by chromate and perhaps by other carcinogens. Immunofluorescent staining of CHO cells and immunoblotting of cell fractions show the reactive antigens are within the cell nucleus. Blotting experiments with the antiserum indicate the chromate-induced p95-DNA complex dissociates in the presence of 2-mercaptoethanol, suggesting similarity to the DPCs formed by carcinogenic platinum compounds. A reduced species of chromium (probably Cr3+) may form DPCs by binding to the nitrogen, oxygen or sulfur atoms of proteins and DNA. These results illustrate the usefulness of immunological detection methods to study specific DNA-protein interactions induced by carcinogens. The possible relevance of DPCs in the carcinogenic process is discussed."
1234778,Susa et al. 1989,Comparative test for cytotoxicity of hexavalent and trivalent chromium in primary cultures of hepatocytes,,Comparative test for cytotoxicity of hexavalent and trivalent chromium in primary cultures of hepatocytes Abs: 
1234777,Blume 1989,A spectrophotometric method for determining the stream sample core diameter of a flow cytometer,"A simple, rapid, and accurate method is described for the determination of flow cytometer stream sample core diameters. A precisely formulated solution of potassium dichromate is introduced as a sample, the stream is collected, and its absorbance is measured using a spectrophotometer. This permits the calculation of the factor by which the original solution was diluted and, given the stream diameter, the sample core diameter.","A spectrophotometric method for determining the stream sample core diameter of a flow cytometer Abs: A simple, rapid, and accurate method is described for the determination of flow cytometer stream sample core diameters. A precisely formulated solution of potassium dichromate is introduced as a sample, the stream is collected, and its absorbance is measured using a spectrophotometer. This permits the calculation of the factor by which the original solution was diluted and, given the stream diameter, the sample core diameter."
1234775,Guin and  Phillips 1989,Erythroderma from systemic contact dermatitis: a complication of systemic gentamicin in a patient with contact allergy to neomycin,"A patient who was sensitive to potassium dichromate and neomycin showed a universal exfoliative erythroderma following intravenous gentamicin therapy. When his ear canals were later treated with a neomycin-containing topical medication, he reacted so severely that the skin of his ears was temporarily depigmented. Withdrawal of aminoglycoside antibiotics along with use of a topical steroid preparation under occlusion brought the eruption under control. Since approximately half of the persons with contact allergy to neomycin will also react to gentamicin, it seems unwise to treat such patients with other intravenous aminoglycosides that are closely related chemically. In our patient, multiple patch tests to other aminoglycosides caused positive reactions to all reagents containing a deoxystreptamine ring, but there was no reaction to streptomycin, which lacks that structure.","Erythroderma from systemic contact dermatitis: a complication of systemic gentamicin in a patient with contact allergy to neomycin Abs: A patient who was sensitive to potassium dichromate and neomycin showed a universal exfoliative erythroderma following intravenous gentamicin therapy. When his ear canals were later treated with a neomycin-containing topical medication, he reacted so severely that the skin of his ears was temporarily depigmented. Withdrawal of aminoglycoside antibiotics along with use of a topical steroid preparation under occlusion brought the eruption under control. Since approximately half of the persons with contact allergy to neomycin will also react to gentamicin, it seems unwise to treat such patients with other intravenous aminoglycosides that are closely related chemically. In our patient, multiple patch tests to other aminoglycosides caused positive reactions to all reagents containing a deoxystreptamine ring, but there was no reaction to streptomycin, which lacks that structure."
1234773,Storrs et al. 1989,Prevalence and relevance of allergic reactions in patients patch tested in North America--1984 to 1985,"Between Jan. 1, 1984, and May 1, 1985, 1199 patients with suspected allergic contact dermatitis were patch tested with 32 &quot;standard&quot; allergens, 707 patients with 19 &quot;vehicle and preservative&quot; allergens, and 613 patients with 10 &quot;special study&quot; allergens. Ten dermatologists representing nine geographic centers collected and analyzed data with the use of the American Academy of Dermatology's mainframe computer in Evanston, Illinois. The most common sensitizers identified were nickel, p-phenylenediamine, quaternium-15, neomycin, thimerosal, formaldehyde, cinnamic aldehyde, ethylenediamine, potassium dichromate, and thiuram mix. Each positive reaction was assessed for its clinical relevance.","Prevalence and relevance of allergic reactions in patients patch tested in North America--1984 to 1985 Abs: Between Jan. 1, 1984, and May 1, 1985, 1199 patients with suspected allergic contact dermatitis were patch tested with 32 &quot;standard&quot; allergens, 707 patients with 19 &quot;vehicle and preservative&quot; allergens, and 613 patients with 10 &quot;special study&quot; allergens. Ten dermatologists representing nine geographic centers collected and analyzed data with the use of the American Academy of Dermatology's mainframe computer in Evanston, Illinois. The most common sensitizers identified were nickel, p-phenylenediamine, quaternium-15, neomycin, thimerosal, formaldehyde, cinnamic aldehyde, ethylenediamine, potassium dichromate, and thiuram mix. Each positive reaction was assessed for its clinical relevance."
1234772,Brandi et al. 1989,The effect of K2Cr2O7 on the growth and morphology of Escherichia coli,"Treatment with 16 microM K2Cr2O7 results is a time-dependent loss of the clonogenicity of E. coli cells. Under the same experimental conditions, optical density values do not change significantly, since cells have the ability to replicate but not to septate. In fact, microscopic analysis of samples taken over 240 min of exposure to the toxin has revealed the formation of filaments. The filamentous response appears similar to that generated by mitomycin C.","The effect of K2Cr2O7 on the growth and morphology of Escherichia coli Abs: Treatment with 16 microM K2Cr2O7 results is a time-dependent loss of the clonogenicity of E. coli cells. Under the same experimental conditions, optical density values do not change significantly, since cells have the ability to replicate but not to septate. In fact, microscopic analysis of samples taken over 240 min of exposure to the toxin has revealed the formation of filaments. The filamentous response appears similar to that generated by mitomycin C."
1234770,Ogawa et al. 1989,Influence of chromium compounds on microbial growth and nucleic acid synthesis,BIOSIS COPYRIGHT: BIOL ABS. RRM BACILLUS-SUBTILIS MUTAGEN CARCINOGEN WASTEWATER TREATMENT CHEMICAL INDUSTRY INDUSTRIAL WASTE,Influence of chromium compounds on microbial growth and nucleic acid synthesis Abs: BIOSIS COPYRIGHT: BIOL ABS. RRM BACILLUS-SUBTILIS MUTAGEN CARCINOGEN WASTEWATER TREATMENT CHEMICAL INDUSTRY INDUSTRIAL WASTE
1234769,Hayashi et al. 1989,Difference between intraperitoneal and oral gavage application in the micronucleus test. The 3rd collaborative study by CSGMT/JEMS.MMS. Collaborative Study Group for the Micronucleus Test/Mammalian Mutagenesis Study Group of the Environmental Mutagen Society of Japan,"In the third collaborative study organized by the Collaborative Study Group for the Micronucleus Test (CSGMT), a task group belonging to the Mammalian Mutagenesis Study subgroup of the Environmental Mutagen Society of Japan (JEMS.MMS), intraperitoneal (i.p.) injection and oral (p.o.) gavage were compared as routes of administration of test chemicals. Two mouse strains, MS/Ae and CD-1, and 17 chemicals with various modes of action were used. The chemicals were 1-beta-D-arabinofuranosylcytosine, 6-mercaptopurine monohydrate, benzo[a]pyrene, 7,12-dimethylbenz[a]anthracene, 2-acetylaminofluorene, phenacetin, cyclophosphamide, ethyl methanesulfonate, N-ethyl-N-nitrosourea, methyl methanesulfonate, mitomycin C, colchicine, vincristine sulfate, potassium bromate, potassium chromate(VI), benzene, and procarbazine hydrochloride. On the basis of the findings of an acute toxicity test and a pilot experiment for dose and sampling time, a full-scale micronucleus test was performed on each chemical. Almost all the chemicals showed a positive response in micronucleus induction by both routes of administration in both mouse strains. Contradictory outcomes were obtained between the i.p. and p.o. routes on potassium chromate in both strains (i.p.: positive, p.o.: negative). In the CD-1 mice, benzene potently induced micronuclei when administered p.o., but gave only a marginal response when administered i.p. Generally, the chemicals induced micronuclei at lower dose levels (mg/kg) when administered i.p. This tendency, however, was decreased or even reversed when the dose was expressed as a percentage of the LD50. Although the i.p. route, an artificial exposure route, is useful to detect the inducibility of micronuclei of a test chemical per se at a small dose, the p.o. route seemed sensitive and valuable enough to evaluate the test chemicals. When the dose levels of chemicals are adjusted on the basis of the LD50, both i.p. injection and p.o. gavage are acceptable as routes of administration in the micronucleus test.","Difference between intraperitoneal and oral gavage application in the micronucleus test. The 3rd collaborative study by CSGMT/JEMS.MMS. Collaborative Study Group for the Micronucleus Test/Mammalian Mutagenesis Study Group of the Environmental Mutagen Society of Japan Abs: In the third collaborative study organized by the Collaborative Study Group for the Micronucleus Test (CSGMT), a task group belonging to the Mammalian Mutagenesis Study subgroup of the Environmental Mutagen Society of Japan (JEMS.MMS), intraperitoneal (i.p.) injection and oral (p.o.) gavage were compared as routes of administration of test chemicals. Two mouse strains, MS/Ae and CD-1, and 17 chemicals with various modes of action were used. The chemicals were 1-beta-D-arabinofuranosylcytosine, 6-mercaptopurine monohydrate, benzo[a]pyrene, 7,12-dimethylbenz[a]anthracene, 2-acetylaminofluorene, phenacetin, cyclophosphamide, ethyl methanesulfonate, N-ethyl-N-nitrosourea, methyl methanesulfonate, mitomycin C, colchicine, vincristine sulfate, potassium bromate, potassium chromate(VI), benzene, and procarbazine hydrochloride. On the basis of the findings of an acute toxicity test and a pilot experiment for dose and sampling time, a full-scale micronucleus test was performed on each chemical. Almost all the chemicals showed a positive response in micronucleus induction by both routes of administration in both mouse strains. Contradictory outcomes were obtained between the i.p. and p.o. routes on potassium chromate in both strains (i.p.: positive, p.o.: negative). In the CD-1 mice, benzene potently induced micronuclei when administered p.o., but gave only a marginal response when administered i.p. Generally, the chemicals induced micronuclei at lower dose levels (mg/kg) when administered i.p. This tendency, however, was decreased or even reversed when the dose was expressed as a percentage of the LD50. Although the i.p. route, an artificial exposure route, is useful to detect the inducibility of micronuclei of a test chemical per se at a small dose, the p.o. route seemed sensitive and valuable enough to evaluate the test chemicals. When the dose levels of chemicals are adjusted on the basis of the LD50, both i.p. injection and p.o. gavage are acceptable as routes of administration in the micronucleus test."
1234768,Shindo et al. 1989,Micronucleus test with potassium chromate(VI) administered intraperitoneally and orally to mice,"The effect of route of administration, intraperitoneal (i.p.) or oral gavage (p.o.), in the mouse micronucleus test was studied with K2CrO4 in 2 mouse strains (MS/Ae and CD-1). A simplified acute toxicity test to estimate the toxic dose levels of K2CrO4 showed that the LD50S were 50 mg/kg i.p. and 300 mg/kg p.o. for MS/Ae and 32 mg/kg i.p. and 180 mg/kg p.o. for CD-1. Based on results of a pilot micronucleus test to determine appropriate dose levels and the optimal sampling time, it was decided to sample bone marrow cells of both strains of mice 24 h after i.p. doses of 10-80 mg/kg and p.o. doses ranging from 20 to 320 mg/kg. K2CrO4 administered i.p. induced micronucleated polychromatic erythrocytes (MNPCEs) dose-dependently in both strains. In contrast, when administered p.o. the chemical failed to induce MNPCEs. These results suggest that this difference between i.p. and p.o. routes is related to a difference of absorption or metabolic fate of chromate in vivo.","Micronucleus test with potassium chromate(VI) administered intraperitoneally and orally to mice Abs: The effect of route of administration, intraperitoneal (i.p.) or oral gavage (p.o.), in the mouse micronucleus test was studied with K2CrO4 in 2 mouse strains (MS/Ae and CD-1). A simplified acute toxicity test to estimate the toxic dose levels of K2CrO4 showed that the LD50S were 50 mg/kg i.p. and 300 mg/kg p.o. for MS/Ae and 32 mg/kg i.p. and 180 mg/kg p.o. for CD-1. Based on results of a pilot micronucleus test to determine appropriate dose levels and the optimal sampling time, it was decided to sample bone marrow cells of both strains of mice 24 h after i.p. doses of 10-80 mg/kg and p.o. doses ranging from 20 to 320 mg/kg. K2CrO4 administered i.p. induced micronucleated polychromatic erythrocytes (MNPCEs) dose-dependently in both strains. In contrast, when administered p.o. the chemical failed to induce MNPCEs. These results suggest that this difference between i.p. and p.o. routes is related to a difference of absorption or metabolic fate of chromate in vivo."
1234767,Chen et al. 1989,"Integration of holographic optical elements with polymer gelatin waveguides on GaAs, LiNbO(3), glass, and aluminum","We have observed waveguiding in thin films of polymer gelatin on GaAs, LiNbO(3), glass, and aluminum substrates. A graded-index profile can be induced in the gelatin layer and tuned by wet processing. This makes it possible to form waveguides on any smooth surface. Locally sensitizing the gelatin waveguide with ammonium dichromate allows us to integrate single and multiplexed gratings on the same substrate to perform various functions for optical interconnects and signal processing. A waveguide grating coupler that converts free-space TEM(00) laser light to a two-dimensional spherical guided wave with 50 degrees angle of divergence has also been demonstrated. An optical clock distribution network on wafer-scale integrated circuits is feasible with this new technology.","Integration of holographic optical elements with polymer gelatin waveguides on GaAs, LiNbO(3), glass, and aluminum Abs: We have observed waveguiding in thin films of polymer gelatin on GaAs, LiNbO(3), glass, and aluminum substrates. A graded-index profile can be induced in the gelatin layer and tuned by wet processing. This makes it possible to form waveguides on any smooth surface. Locally sensitizing the gelatin waveguide with ammonium dichromate allows us to integrate single and multiplexed gratings on the same substrate to perform various functions for optical interconnects and signal processing. A waveguide grating coupler that converts free-space TEM(00) laser light to a two-dimensional spherical guided wave with 50 degrees angle of divergence has also been demonstrated. An optical clock distribution network on wafer-scale integrated circuits is feasible with this new technology."
1234765,Schöpf and  Baumgårtner 1989,Patch testing in atopic dermatitis,"Because patients with atopic dermatitis are less prone to type IV allergies, there has been controversy regarding the role of patch testing in these patients. However, recent observations indicate that patch testing with standard allergens often adds valuable information about contact sensitivity in these patients.","Patch testing in atopic dermatitis Abs: Because patients with atopic dermatitis are less prone to type IV allergies, there has been controversy regarding the role of patch testing in these patients. However, recent observations indicate that patch testing with standard allergens often adds valuable information about contact sensitivity in these patients."
1234763,Christenson et al. 1989,The effect of combined treatment with potassium dichromate and maleic acid on renal function in the rat,"Subthreshold doses of potassium dichromate (K2Cr2O7) have been shown to enhance or potentiate the nephrotoxic effects of mercuric chloride and citrinin. The mechanism of this effect is unknown. The purpose of this study was to examine the phenomenon further by investigating the interaction of K2Cr2O7 with maleic acid, a nephrotoxicant with an action though to be different from those above. Male rats were housed in stainless steel metabolism cages and received a single intraperitoneal injection of maleic acid (300 mg/kg). K2Cr2O7 (10 mg/kg s.c.) or the combination of maleic acid plus K2Cr2O7. While treatment with either agent alone produced only minimal alterations in renal function, the combination of agents produced marked changes in 24 h urine volume, glucose excretion and osmolality. Water consumption was unaffected by the combined treatment. A marked decline in the capacity of renal slices to accumulate both organic anions (p-aminohippurate) and cations (tetraethylammonium) was observed after treatment with both substances. Modifications in renal and hepatic non-protein sulfhydryl content also were observed. These results suggest that K2Cr2O7, as was observed with both mercury and citrinin, enhanced or potentiated the nephrotoxic effects of maleic acid, probably in the proximal tubule, the principal site of glucose reabsorption and organic ion secretion.","The effect of combined treatment with potassium dichromate and maleic acid on renal function in the rat Abs: Subthreshold doses of potassium dichromate (K2Cr2O7) have been shown to enhance or potentiate the nephrotoxic effects of mercuric chloride and citrinin. The mechanism of this effect is unknown. The purpose of this study was to examine the phenomenon further by investigating the interaction of K2Cr2O7 with maleic acid, a nephrotoxicant with an action though to be different from those above. Male rats were housed in stainless steel metabolism cages and received a single intraperitoneal injection of maleic acid (300 mg/kg). K2Cr2O7 (10 mg/kg s.c.) or the combination of maleic acid plus K2Cr2O7. While treatment with either agent alone produced only minimal alterations in renal function, the combination of agents produced marked changes in 24 h urine volume, glucose excretion and osmolality. Water consumption was unaffected by the combined treatment. A marked decline in the capacity of renal slices to accumulate both organic anions (p-aminohippurate) and cations (tetraethylammonium) was observed after treatment with both substances. Modifications in renal and hepatic non-protein sulfhydryl content also were observed. These results suggest that K2Cr2O7, as was observed with both mercury and citrinin, enhanced or potentiated the nephrotoxic effects of maleic acid, probably in the proximal tubule, the principal site of glucose reabsorption and organic ion secretion."
1234762,Sinclair and  Hindson 1989,Chromate in colour television tube manufacture,"A 60 year old man had dermatitis involving the backs of his hands, face, and chest intermittently for 10 years. Patch tests to the European standard series revealed ++ results at 48 and 96 hours to 0.5 percent potassium-dichromate (7789006). He was also ++ to 0.5 percent aqueous ammonium-dichromate (7789095) but nothing else. The man was employed in the manufacture of tubes for color television sets. Each tube was coated on its inside with phosphors, by dissolving the phosphors in polyvinyl-alcohol which was then sprayed onto the screen. The coating was irradiated with ultraviolet-A in the presence of 2 percent aqueous ammonium-dichromate to ensure adhesion. The rash cleared within a few weeks of his being removed from the spraying process. The patient had been off work for 3 months for other reasons and had no rash. Each attack has resolved rapidly on removal from exposure.","Chromate in colour television tube manufacture Abs: A 60 year old man had dermatitis involving the backs of his hands, face, and chest intermittently for 10 years. Patch tests to the European standard series revealed ++ results at 48 and 96 hours to 0.5 percent potassium-dichromate (7789006). He was also ++ to 0.5 percent aqueous ammonium-dichromate (7789095) but nothing else. The man was employed in the manufacture of tubes for color television sets. Each tube was coated on its inside with phosphors, by dissolving the phosphors in polyvinyl-alcohol which was then sprayed onto the screen. The coating was irradiated with ultraviolet-A in the presence of 2 percent aqueous ammonium-dichromate to ensure adhesion. The rash cleared within a few weeks of his being removed from the spraying process. The patient had been off work for 3 months for other reasons and had no rash. Each attack has resolved rapidly on removal from exposure."
1234761,Stransky and  Krasteva 1989,Changing patterns of contact sensitivity in Sofia,"1237 patients with contact sensitization were patch tested five times with the standard patch test series at 3-year intervals. The study was carried out during the period 1975-1987. The results point out the increasing significance of the most common allergens in the industrially developed countries: potassium dichromate, isopropylaminodiphenylamine, formalin, p-phenylenediamine and nickel sulfate.","Changing patterns of contact sensitivity in Sofia Abs: 1237 patients with contact sensitization were patch tested five times with the standard patch test series at 3-year intervals. The study was carried out during the period 1975-1987. The results point out the increasing significance of the most common allergens in the industrially developed countries: potassium dichromate, isopropylaminodiphenylamine, formalin, p-phenylenediamine and nickel sulfate."
1234759,Burrows et al. 1989,Trial of 0.5% versus 0.375% potassium dichromate. European Environmental and Contact Dermatitis Research Group (EECDRG),,Trial of 0.5% versus 0.375% potassium dichromate. European Environmental and Contact Dermatitis Research Group (EECDRG) Abs: 
1234757,Borges and  Wetterhahn 1989,Chromium cross-links glutathione and cysteine to DNA,"The formation of chromium-DNA adducts, and chromium-mediated peptide-DNA or amino acid-DNA cross-links was measured after treatment of calf thymus DNA and defined DNA polynucleotides in vitro with potassium dichromate in the presence of glutathione or cysteine. The level of chromium bound to DNA after reaction with chromium(VI) in the presence of glutathione increased with increasing glutathione concentration to a level of approximately 1.4 x 10(-2) chromium per nucleotide. Glutathione and chromium were associated with the DNA in a 1:1 ratio. Reaction of chromium(VI) with DNA in the presence of cysteine led to a maximal level of chromium binding that was 10-fold lower than that measured with glutathione, with 2-4 cysteine bound per chromium. The thiol-chromium-DNA complexes were stable to dialysis at room temperature against diethylenetriaminepentaacetic acid, orthophenanthroline and ethylenediaminetetraacetic acid. However, when the chromium-DNA complexes were dialyzed against ethylenediaminetetraacetic acid at 37 degrees C to chelate bound chromium, equivalent amounts of chromium and thiol were lost from the DNA, suggesting that thiol was associated with the DNA-bound chromium. These results suggest that chromium mediates cross-linking of cysteine and glutathione to DNA, to form glutathione-chromium-DNA and (cysteine)2-4-chromium-DNA complexes. In order to probe the DNA base and sequence specificity of glutathione-chromium-DNA adduct formation, chromium and glutathione binding to polynucleotides of defined composition was determined. Preferential binding of chromium to guanine-containing polynucleotides was observed. These results suggest that the interaction of chromium with thiol-containing amino acids and peptides may be important in chromium genotoxicity, and indicate that the thiol-activated chromium may target guanine bases in DNA.","Chromium cross-links glutathione and cysteine to DNA Abs: The formation of chromium-DNA adducts, and chromium-mediated peptide-DNA or amino acid-DNA cross-links was measured after treatment of calf thymus DNA and defined DNA polynucleotides in vitro with potassium dichromate in the presence of glutathione or cysteine. The level of chromium bound to DNA after reaction with chromium(VI) in the presence of glutathione increased with increasing glutathione concentration to a level of approximately 1.4 x 10(-2) chromium per nucleotide. Glutathione and chromium were associated with the DNA in a 1:1 ratio. Reaction of chromium(VI) with DNA in the presence of cysteine led to a maximal level of chromium binding that was 10-fold lower than that measured with glutathione, with 2-4 cysteine bound per chromium. The thiol-chromium-DNA complexes were stable to dialysis at room temperature against diethylenetriaminepentaacetic acid, orthophenanthroline and ethylenediaminetetraacetic acid. However, when the chromium-DNA complexes were dialyzed against ethylenediaminetetraacetic acid at 37 degrees C to chelate bound chromium, equivalent amounts of chromium and thiol were lost from the DNA, suggesting that thiol was associated with the DNA-bound chromium. These results suggest that chromium mediates cross-linking of cysteine and glutathione to DNA, to form glutathione-chromium-DNA and (cysteine)2-4-chromium-DNA complexes. In order to probe the DNA base and sequence specificity of glutathione-chromium-DNA adduct formation, chromium and glutathione binding to polynucleotides of defined composition was determined. Preferential binding of chromium to guanine-containing polynucleotides was observed. These results suggest that the interaction of chromium with thiol-containing amino acids and peptides may be important in chromium genotoxicity, and indicate that the thiol-activated chromium may target guanine bases in DNA."
1234756,Maurer and  Hess 1989,The maximization test for skin sensitization potential--updating the standard protocol and validation of a modified protocol,"Since Magnusson and Kligman (1969) first described the maximization test, for assessing skin sensitization potential, the test has been substantially validated and data have been obtained on dose-activity relationships. The original method remains acceptable for qualified risk assessment but several modified protocols have been developed to overcome problems with particular test materials. A modified maximization test is described for compounds that are not soluble in the standard vehicles and, therefore, not injectable, and for formulations, to simulate user exposure conditions. The test compounds 2,4-dinitrochlorobenzene, p-phenylenediamine, 1-(3-chlorophenyl)-3- (4-chlorophenyl)-2-pyrazoline, formaldehyde, benzocain, penicillin G, benzylsalicylate, potassium dichromate and isoeugenol, all gave positive reactions. The incidences of positive reactions varied with the sensitization potentials of the compounds. The results for the first six compounds listed above were compared with those obtained by the standard procedure and were found to be similar. We propose that testing guidelines for skin sensitization should accommodate validated modifications of existing standard procedures.","The maximization test for skin sensitization potential--updating the standard protocol and validation of a modified protocol Abs: Since Magnusson and Kligman (1969) first described the maximization test, for assessing skin sensitization potential, the test has been substantially validated and data have been obtained on dose-activity relationships. The original method remains acceptable for qualified risk assessment but several modified protocols have been developed to overcome problems with particular test materials. A modified maximization test is described for compounds that are not soluble in the standard vehicles and, therefore, not injectable, and for formulations, to simulate user exposure conditions. The test compounds 2,4-dinitrochlorobenzene, p-phenylenediamine, 1-(3-chlorophenyl)-3- (4-chlorophenyl)-2-pyrazoline, formaldehyde, benzocain, penicillin G, benzylsalicylate, potassium dichromate and isoeugenol, all gave positive reactions. The incidences of positive reactions varied with the sensitization potentials of the compounds. The results for the first six compounds listed above were compared with those obtained by the standard procedure and were found to be similar. We propose that testing guidelines for skin sensitization should accommodate validated modifications of existing standard procedures."
1234755,Rose et al. 1989,Evaluation of immunofluorescence techniques for detection of Cryptosporidium oocysts and Giardia cysts from environmental samples,"Cryptosporidium and Giardia species are enteric protozoa which cause waterborne disease. The detection of these organisms in water relies on the detection of the oocyst and cyst forms or stages. Monoclonal and polyclonal antibodies were compared for their abilities to react with Giardia cysts and Cryptosporidium oocysts after storage in water, 3.7% formaldehyde, and 2.5% potassium dichromate, upon exposure to bleach, and in environmental samples. Three monoclonal antibodies to Cryptosporidium parvum were evaluated. Each test resulted in an equivalent detection of the oocysts after storage, after exposure to bleach, and in environmental samples. Oocyst levels declined slightly after 20 to 22 weeks of storage in water, and oocyst fluorescence and morphology were dull and atypical. Oocyst counts decreased after exposure to 2,500 mg of sodium hypochlorite per liter, and fluorescence and phase-contrast counts were similar. Sediment due to algae and clays found in environmental samples interfered with the detection of oocysts on membrane filters. Two monoclonal antibodies and a polyclonal antibody directed against Giardia lamblia cysts were evaluated. From the same seeded preparations, significantly greater counts were obtained with the polyclonal antibody. Of the two monoclonal antibodies, one resulted in significantly lower cyst counts. In preliminary studies, the differences between antibodies were not apparent when used on the environmental wastewater samples. After 20 to 22 weeks in water, cyst levels declined significantly by 67%. Cysts were not detected with monoclonal antibodies after exposure to approximately 5,000 mg of sodium hypochlorite per liter.","Evaluation of immunofluorescence techniques for detection of Cryptosporidium oocysts and Giardia cysts from environmental samples Abs: Cryptosporidium and Giardia species are enteric protozoa which cause waterborne disease. The detection of these organisms in water relies on the detection of the oocyst and cyst forms or stages. Monoclonal and polyclonal antibodies were compared for their abilities to react with Giardia cysts and Cryptosporidium oocysts after storage in water, 3.7% formaldehyde, and 2.5% potassium dichromate, upon exposure to bleach, and in environmental samples. Three monoclonal antibodies to Cryptosporidium parvum were evaluated. Each test resulted in an equivalent detection of the oocysts after storage, after exposure to bleach, and in environmental samples. Oocyst levels declined slightly after 20 to 22 weeks of storage in water, and oocyst fluorescence and morphology were dull and atypical. Oocyst counts decreased after exposure to 2,500 mg of sodium hypochlorite per liter, and fluorescence and phase-contrast counts were similar. Sediment due to algae and clays found in environmental samples interfered with the detection of oocysts on membrane filters. Two monoclonal antibodies and a polyclonal antibody directed against Giardia lamblia cysts were evaluated. From the same seeded preparations, significantly greater counts were obtained with the polyclonal antibody. Of the two monoclonal antibodies, one resulted in significantly lower cyst counts. In preliminary studies, the differences between antibodies were not apparent when used on the environmental wastewater samples. After 20 to 22 weeks in water, cyst levels declined significantly by 67%. Cysts were not detected with monoclonal antibodies after exposure to approximately 5,000 mg of sodium hypochlorite per liter."
1234754,Tato et al. 1990,Observations on the contrasting reaction of some electron dense stains applied on epoxy-embedded tissue sections,"Epon sections from glutaraldehyde-fixed rat bone marrow were treated with aqueous solutions of the following electron contrasting agents: uranyl acetate, ruthenium red, potassium permanganate, potassium dichromate, stannous chloride, palladium (II) chloride, sodium molybdate, phosphomolybdic acid, molybdenum heteropolyblue, phosphotungstic acid, iron(II)-phenanthroline, aluminium-hematoxylin, mercurochrome, cuprolinic blue, and sirius light turquoise blue. At the ultrastructural level, a high degree of electron opacity was always observed in mast cell granules and the crystalline inclusion (internum) of eosinophil granules. The chromatin revealed a somewhat lower and variable contrasting reaction, while the matrix (externum) of eosinophil granules appeared with scarce or no contrast. This pattern of electron opacity showed no correlation with the type of agent used; therefore, it can be assumed that binding processes based on the own chemical reactivity of the compounds are rather of secondary importance. The differential epoxy resin embedding of cell structures and the variable access of aqueous reagents through the non-polar plastic could be the predominant factors which account for these contrasting reactions.","Observations on the contrasting reaction of some electron dense stains applied on epoxy-embedded tissue sections Abs: Epon sections from glutaraldehyde-fixed rat bone marrow were treated with aqueous solutions of the following electron contrasting agents: uranyl acetate, ruthenium red, potassium permanganate, potassium dichromate, stannous chloride, palladium (II) chloride, sodium molybdate, phosphomolybdic acid, molybdenum heteropolyblue, phosphotungstic acid, iron(II)-phenanthroline, aluminium-hematoxylin, mercurochrome, cuprolinic blue, and sirius light turquoise blue. At the ultrastructural level, a high degree of electron opacity was always observed in mast cell granules and the crystalline inclusion (internum) of eosinophil granules. The chromatin revealed a somewhat lower and variable contrasting reaction, while the matrix (externum) of eosinophil granules appeared with scarce or no contrast. This pattern of electron opacity showed no correlation with the type of agent used; therefore, it can be assumed that binding processes based on the own chemical reactivity of the compounds are rather of secondary importance. The differential epoxy resin embedding of cell structures and the variable access of aqueous reagents through the non-polar plastic could be the predominant factors which account for these contrasting reactions."
1234751,Yamashima and  Yamashita 1990,"Histological, ultrastructural and chromatographical discrimination of phospholipids in meningiomas","Phospholipids in meningiomas were studied by light and electron microscopy, and by high-performance liquid chromatography. They were microscopically demonstrated in six of the ten cases by Sudan III staining after the fixation with potassium dichromate. However, the conventional ultrastructural fixation with glutaraldehyde and osmium tetroxide failed to confirm phospholipids, as most of them were dissolved during dehydration. In contrast, the specimens pretreated with tannic acid before osmication ultrastructurally retained phospholipids which were represented by multilamellar bodies or ribbon-like rings. Both were found in 23 of the 30 cases within the cytoplasm, among the plasma membranes and in the extracellular matrices. The outermost lamella or ribbon showed a direct continuity from the neighbouring plasma membranes of the cytoplasm or the mitochondria. The multilamellar bodies showed an overall distribution, while the ribbon-like rings were predominantly distributed around the psammoma bodies. Precipitation of hydroxyapatite crystals within the ribbon-like rings resulted in matrix minerals of psammoma bodies. Chromatographical analyses of meningiomas disclosed phospholipids including phosphatidyl ethanolamine, phosphatidyl choline, phosphatidyl serine, sphingomyelin and phosphatidyl inositol in that order. Psammomatous meningiomas contained a higher percentage of phosphatidyl serine than non-psammomatous tumors. Ultrastructural study of synthetic phospholipids adequately treated with tannic acid showed that the multilamellar bodies were similar to phosphatidyl choline, while the ribbon-like rings were similar to phosphatidyl serine. The role of phospholipids in meningiomas is discussed.","Histological, ultrastructural and chromatographical discrimination of phospholipids in meningiomas Abs: Phospholipids in meningiomas were studied by light and electron microscopy, and by high-performance liquid chromatography. They were microscopically demonstrated in six of the ten cases by Sudan III staining after the fixation with potassium dichromate. However, the conventional ultrastructural fixation with glutaraldehyde and osmium tetroxide failed to confirm phospholipids, as most of them were dissolved during dehydration. In contrast, the specimens pretreated with tannic acid before osmication ultrastructurally retained phospholipids which were represented by multilamellar bodies or ribbon-like rings. Both were found in 23 of the 30 cases within the cytoplasm, among the plasma membranes and in the extracellular matrices. The outermost lamella or ribbon showed a direct continuity from the neighbouring plasma membranes of the cytoplasm or the mitochondria. The multilamellar bodies showed an overall distribution, while the ribbon-like rings were predominantly distributed around the psammoma bodies. Precipitation of hydroxyapatite crystals within the ribbon-like rings resulted in matrix minerals of psammoma bodies. Chromatographical analyses of meningiomas disclosed phospholipids including phosphatidyl ethanolamine, phosphatidyl choline, phosphatidyl serine, sphingomyelin and phosphatidyl inositol in that order. Psammomatous meningiomas contained a higher percentage of phosphatidyl serine than non-psammomatous tumors. Ultrastructural study of synthetic phospholipids adequately treated with tannic acid showed that the multilamellar bodies were similar to phosphatidyl choline, while the ribbon-like rings were similar to phosphatidyl serine. The role of phospholipids in meningiomas is discussed."
1234750,Langård 1990,One hundred years of chromium and cancer: a review of epidemiological evidence and selected case reports,"The present review is motivated by the fact that 100 years have passed since the first cancer case in a chromium worker was reported in Scotland. Old and recent case reports and epidemiological studies among chromate workers are reviewed to elucidate the importance of valency states and water solubility of chromium compounds for carcinogenic potency. It is concluded that all chromium[VI] compounds should be considered carcinogenic among exposed populations, and that no evidence has been presented indicating that human exposure to chromium[III] is associated with increased cancer risk. Strong evidence has been presented that zinc chromate is a potent carcinogen and suggests that calcium chromate may be a potent carcinogen. Evidence also suggests that water-soluble chromates in general may be more potent carcinogens than those with low solubility. Primary and secondary prevention of chromate-related cancer and the success in preventive measures are briefly discussed, and recommendations for future research are made.","One hundred years of chromium and cancer: a review of epidemiological evidence and selected case reports Abs: The present review is motivated by the fact that 100 years have passed since the first cancer case in a chromium worker was reported in Scotland. Old and recent case reports and epidemiological studies among chromate workers are reviewed to elucidate the importance of valency states and water solubility of chromium compounds for carcinogenic potency. It is concluded that all chromium[VI] compounds should be considered carcinogenic among exposed populations, and that no evidence has been presented indicating that human exposure to chromium[III] is associated with increased cancer risk. Strong evidence has been presented that zinc chromate is a potent carcinogen and suggests that calcium chromate may be a potent carcinogen. Evidence also suggests that water-soluble chromates in general may be more potent carcinogens than those with low solubility. Primary and secondary prevention of chromate-related cancer and the success in preventive measures are briefly discussed, and recommendations for future research are made."
1234749,Riemann and  Lindgaard-Jørgensen 1990,Effects of toxic substances on natural bacterial assemblages determined by means of [h]thymidine incorporation,"The effects of 3,5-dichlorophenol, 2,4-dinitrophenol, and potassium dichromate on natural bacterial assemblages were examined by means of [H]thymidine incorporation into trichloroacetic acid-insoluble material. Results from a large number of coastal marine and freshwater samples suggest the following. (i) The effects of the three toxicants included reductions in the bacterial cell number as well as changes in rates of [H]thymidine incorporation and in [H]thymidine incorporation per cell. The concentrations that inhibited [H]thymidine incorporation by 50% ranged from 3 to 11 mg liter for 3,5-dichlorophenol, 6 to 10 mg liter for 2,4-dinitrophenol, and 21 to 123 mg liter for potassium dichromate, with a tendency to higher values in bacterial assemblages from more eutrophic environments. (ii) The effects of 3,5-dichlorophenol and potassium dichromate determined by [H]leucine incorporation into bacterial protein were similar or larger than those obtained from [H]thymidine incorporation. (iii) Two to four hours of exposure to the toxicants was necessary before stable maximum effects were found in [H]thymidine incorporation. (iv) Storage of natural environmental samples should be avoided, since tests with water stored for 1 to 3 days sometimes produced results different from results obtained from in situ tests. (v) The effects of 3,5-dichlorophenol, 2,4-dinitrophenol, and potassium dichromate on natural bacterial assemblages were relatively constant during periods with different growth rates in the assemblages, during various periods of the year, and between samples from freshwater and marine localities. With some precautions, [H]thymidine incorporation can be used as a quick and sensitive method for determining the effects of toxicants on aquatic bacterial assemblages from natural environmental samples.","Effects of toxic substances on natural bacterial assemblages determined by means of [h]thymidine incorporation Abs: The effects of 3,5-dichlorophenol, 2,4-dinitrophenol, and potassium dichromate on natural bacterial assemblages were examined by means of [H]thymidine incorporation into trichloroacetic acid-insoluble material. Results from a large number of coastal marine and freshwater samples suggest the following. (i) The effects of the three toxicants included reductions in the bacterial cell number as well as changes in rates of [H]thymidine incorporation and in [H]thymidine incorporation per cell. The concentrations that inhibited [H]thymidine incorporation by 50% ranged from 3 to 11 mg liter for 3,5-dichlorophenol, 6 to 10 mg liter for 2,4-dinitrophenol, and 21 to 123 mg liter for potassium dichromate, with a tendency to higher values in bacterial assemblages from more eutrophic environments. (ii) The effects of 3,5-dichlorophenol and potassium dichromate determined by [H]leucine incorporation into bacterial protein were similar or larger than those obtained from [H]thymidine incorporation. (iii) Two to four hours of exposure to the toxicants was necessary before stable maximum effects were found in [H]thymidine incorporation. (iv) Storage of natural environmental samples should be avoided, since tests with water stored for 1 to 3 days sometimes produced results different from results obtained from in situ tests. (v) The effects of 3,5-dichlorophenol, 2,4-dinitrophenol, and potassium dichromate on natural bacterial assemblages were relatively constant during periods with different growth rates in the assemblages, during various periods of the year, and between samples from freshwater and marine localities. With some precautions, [H]thymidine incorporation can be used as a quick and sensitive method for determining the effects of toxicants on aquatic bacterial assemblages from natural environmental samples."
1234748,Landi et al. 1990,Digestion method for the determination of mercury in vegetable matrices by cold vapour atomic absorption spectrometry,"A simple and rapid wet-digestion procedure is described for the determination of total mercury in botanical samples by cold vapour atomic absorption spectrometry. The method is based on the oxidising properties of potassium dichromate in dilute sulphuric acid and was tested on two National Institute of Standards and Technology Standard Reference Materials. The mass of the samples taken for analysis was about 0.5 g in all instances, corresponding to an amount of mercury of the order of 0.075-0.040 micrograms depending on the material. The results were compared with those obtained using the Association of Official Analytical Chemists official digestion technique, which involves the use of nitric and sulphuric acids, and a second technique based on the action of nitric and perchloric acids. The proposed method provided better accuracy and showed good precision. Its ability to achieve the decomposition of two organomercurials for full mercury recovery was verified.","Digestion method for the determination of mercury in vegetable matrices by cold vapour atomic absorption spectrometry Abs: A simple and rapid wet-digestion procedure is described for the determination of total mercury in botanical samples by cold vapour atomic absorption spectrometry. The method is based on the oxidising properties of potassium dichromate in dilute sulphuric acid and was tested on two National Institute of Standards and Technology Standard Reference Materials. The mass of the samples taken for analysis was about 0.5 g in all instances, corresponding to an amount of mercury of the order of 0.075-0.040 micrograms depending on the material. The results were compared with those obtained using the Association of Official Analytical Chemists official digestion technique, which involves the use of nitric and sulphuric acids, and a second technique based on the action of nitric and perchloric acids. The proposed method provided better accuracy and showed good precision. Its ability to achieve the decomposition of two organomercurials for full mercury recovery was verified."
1234747,Eun and  Marks 1990,Dose-response relationships for topically applied antigens,"Patch-test responses to serially diluted nickel sulphate and potassium dichromate solutions in patients with nickel and chrome sensitivity were assessed by pulsed A-scan ultrasound to determine skin thickness and laser-Doppler flowmeter techniques to evaluate blood flow, as well as clinical scoring. There was a relationship between the dose of antigen and the test responses as measured by ultrasound and laser-Doppler flowmeter techniques in both nickel and chrome sensitive patients. Our data suggest that both techniques may be useful in the detection of allergic contact dermatitis in which there is a doubtful patch-test reaction as well as in experimental sensitization studies.","Dose-response relationships for topically applied antigens Abs: Patch-test responses to serially diluted nickel sulphate and potassium dichromate solutions in patients with nickel and chrome sensitivity were assessed by pulsed A-scan ultrasound to determine skin thickness and laser-Doppler flowmeter techniques to evaluate blood flow, as well as clinical scoring. There was a relationship between the dose of antigen and the test responses as measured by ultrasound and laser-Doppler flowmeter techniques in both nickel and chrome sensitive patients. Our data suggest that both techniques may be useful in the detection of allergic contact dermatitis in which there is a doubtful patch-test reaction as well as in experimental sensitization studies."
1234746,Ueno et al. 1990,Uptake and distribution of chromium in isolated rat hepatocytes and its relation to cellular injury,"In order to study the difference of uptake and distribution between hexavalent (Cr6+) and trivalent (Cr3+) chromium in isolated rat hepatocytes, the cells were incubated with Cr6+ or Cr3+ (1 mM Cr) at 37 degrees C for up to 60 min. Leakage of lactate dehydrogenase from the hepatocytes into the suspension medium as an indicator of cellular injury was facilitated by Cr6+ (K2Cr2O7) at 60 min of incubation, whereas Cr3+ [Cr(NO3)3] had no effect. After 60 min of incubation with Cr6+, about 33% of the added Cr was found in the hepatocytes, whereas incubation with Cr3+ resulted in transfer of about 66% of the added Cr to the cells. After 20 and 40 min of incubation with Cr6+, about 39% of cellular Cr was found in the cytosolic fraction of hepatocytes, followed by a reduction to about 35% after 60 min of incubation. However, Cr detected in the cytosolic fraction of hepatocytes incubated with Cr3+ was about 1% of cellular Cr. Cr-binding substances in the cytosolic fraction of hepatocytes incubated with Cr6+ were eluted with two Cr peaks by Sephadex G-200 chromatography. These Cr-binding substances in the low-molecular-weight fractions were separable into at least two substances by thin-layer chromatography. These results suggest that Cr6+ readily passes through the cell membrane and combines with substances already present in the cytosolic fraction of hepatocytes, unlike metallothionein induced by cadmium, followed by detoxification. Consequently, cellular injury might be induced by Cr6+ which could not combine with LMCr in the cytosolic space of the hepatocytes.","Uptake and distribution of chromium in isolated rat hepatocytes and its relation to cellular injury Abs: In order to study the difference of uptake and distribution between hexavalent (Cr6+) and trivalent (Cr3+) chromium in isolated rat hepatocytes, the cells were incubated with Cr6+ or Cr3+ (1 mM Cr) at 37 degrees C for up to 60 min. Leakage of lactate dehydrogenase from the hepatocytes into the suspension medium as an indicator of cellular injury was facilitated by Cr6+ (K2Cr2O7) at 60 min of incubation, whereas Cr3+ [Cr(NO3)3] had no effect. After 60 min of incubation with Cr6+, about 33% of the added Cr was found in the hepatocytes, whereas incubation with Cr3+ resulted in transfer of about 66% of the added Cr to the cells. After 20 and 40 min of incubation with Cr6+, about 39% of cellular Cr was found in the cytosolic fraction of hepatocytes, followed by a reduction to about 35% after 60 min of incubation. However, Cr detected in the cytosolic fraction of hepatocytes incubated with Cr3+ was about 1% of cellular Cr. Cr-binding substances in the cytosolic fraction of hepatocytes incubated with Cr6+ were eluted with two Cr peaks by Sephadex G-200 chromatography. These Cr-binding substances in the low-molecular-weight fractions were separable into at least two substances by thin-layer chromatography. These results suggest that Cr6+ readily passes through the cell membrane and combines with substances already present in the cytosolic fraction of hepatocytes, unlike metallothionein induced by cadmium, followed by detoxification. Consequently, cellular injury might be induced by Cr6+ which could not combine with LMCr in the cytosolic space of the hepatocytes."
1234745,Doco et al. 1990,Structure of an exocellular polysaccharide produced by Streptococcus thermophilus,"Streptococcus thermophilus strains grown on skimmed milk produced a viscosifying, exocellular, and water-soluble polysaccharide which contains D-glucose, D-galactose, and N-acetyl-D-galactosamine in the ratio of 1:2:1. Methylation analysis identified the glycosidic linkages in the tetrasaccharidic repeating-unit, and Smith degradation and nitrous deamination after N-deacetylation gave the sequence of monosaccharides in the repeating-unit. The anomeric configurations of the sugar residues were determined by oxidation of the peracetylated polysaccharide with chromium trioxide and by 1H- and 13C-n.m.r. spectroscopy. The following structure was assigned to the repeating unit of the polysaccharide,----3)-beta-D-Galp-(1----3)-[alpha-D-Galp-(1----6)]-beta- D- Glcp-(1----3)-alpha-D-GalpNAc-(1----.","Structure of an exocellular polysaccharide produced by Streptococcus thermophilus Abs: Streptococcus thermophilus strains grown on skimmed milk produced a viscosifying, exocellular, and water-soluble polysaccharide which contains D-glucose, D-galactose, and N-acetyl-D-galactosamine in the ratio of 1:2:1. Methylation analysis identified the glycosidic linkages in the tetrasaccharidic repeating-unit, and Smith degradation and nitrous deamination after N-deacetylation gave the sequence of monosaccharides in the repeating-unit. The anomeric configurations of the sugar residues were determined by oxidation of the peracetylated polysaccharide with chromium trioxide and by 1H- and 13C-n.m.r. spectroscopy. The following structure was assigned to the repeating unit of the polysaccharide,----3)-beta-D-Galp-(1----3)-[alpha-D-Galp-(1----6)]-beta- D- Glcp-(1----3)-alpha-D-GalpNAc-(1----."
1234744,Madrid et al. 1990,Evaluation of oxidant media for the determination of lead in food slurries by hydride generation atomic absorption spectrometry,"Several oxidant media were evaluated for the generation of lead hydride from slurry samples and their application to the determination of lead in vegetables and fish by hydride generation atomic absorption spectrometry. Three oxidant - acid media were compared: hydrogen peroxide - nitric acid, ammonium persulphate - nitric acid and potassium dichromate - lactic acid. The powdered samples were suspended in Triton X-100 and shaken with 10.0 g of blown zirconia spheres until a slurry was formed. The potassium dichromate - lactic acid medium was the most satisfactory for the determination of lead in fish and vegetables, providing the lowest detection limits as a result of its high sensitivity and low blank values. The ammonium persulphate - nitric acid medium gave good accuracy, precision and selectivity for vegetables (1-2 p.p.m. of lead); however, with fish (0.1-1 p.p.m. of lead) it was only a semi-quantitative medium for the determination of lead owing to its lack of sensitivity and selectivity. The hydrogen peroxide - nitric acid medium was unsatisfactory for the generation of lead hydride from slurry samples because of decomposition of hydrogen peroxide by the organic matter in the sample.","Evaluation of oxidant media for the determination of lead in food slurries by hydride generation atomic absorption spectrometry Abs: Several oxidant media were evaluated for the generation of lead hydride from slurry samples and their application to the determination of lead in vegetables and fish by hydride generation atomic absorption spectrometry. Three oxidant - acid media were compared: hydrogen peroxide - nitric acid, ammonium persulphate - nitric acid and potassium dichromate - lactic acid. The powdered samples were suspended in Triton X-100 and shaken with 10.0 g of blown zirconia spheres until a slurry was formed. The potassium dichromate - lactic acid medium was the most satisfactory for the determination of lead in fish and vegetables, providing the lowest detection limits as a result of its high sensitivity and low blank values. The ammonium persulphate - nitric acid medium gave good accuracy, precision and selectivity for vegetables (1-2 p.p.m. of lead); however, with fish (0.1-1 p.p.m. of lead) it was only a semi-quantitative medium for the determination of lead owing to its lack of sensitivity and selectivity. The hydrogen peroxide - nitric acid medium was unsatisfactory for the generation of lead hydride from slurry samples because of decomposition of hydrogen peroxide by the organic matter in the sample."
1234743,CSGMT/JEMS.MMS 1990,Single versus multiple dosing in the micronucleus test: The summary of the fourth collaborative study by CSGMT/JEMS.MMS,"The effects of multiple dosing in the micronucleus test were studied by treating male CD-1 mice 1, 2, and 4 times i.p. with various doses of 11 chemicals and by sampling bone marrow cells 6, 24, 48, and/or 72 h after the final dosing. The chemicals used were 2-acetylaminofluorene (2-AAF), 1-beta-D-arabinofuranosylcytosine (ARA-C), 7,12-dimethylbenz[a]anthracene (DMBA), ethyl methanesulfonate (EMS), N-ethyl-N-nitrosourea (ENU), 6-mercaptopurine (6-MP), phenacetin (PHEN), 5-fluorouracil (5-FU), methotrexate (MTX), benzene (BEN), and potassium chromate (K2CrO4). MTX, an inhibitor of nucleotide synthesis, was a weak micronucleus inducer after single dosing, but clearly positive after multiple dosing. Although ARA-C, 5-FU, and 6-MP became positive after single dosing, the multiple dosing enhanced the effects of these base analogues. ENU, DMBA, and BEN, at some doses and sampling times, also showed increased responses by multiple dosing, but a severe trade-off occurred enhanced toxicity tended to reduce the bone marrow cells, especially at 4 dosings, making the examination of micronuclei difficult. PHEN showed the multiple-dosing effect after 2 doses, but the effect disappeared at quadruple dosing. No apparent multiple-dosing effects were observed with 2-AAF, EMS, and K2CrO4, which gave similar incidences of micronuclei after single and double dosing. The original double dosing and sampling 6 h after the second injection method of Schmid (1975) was less sensitive than the modified method, i.e., sampling 24 h after the second dosing. The latter regimen is recommended for the general screening for the following reasons. (1) It was the most sensitive protocol among those tested here and detected all test chemicals as clastogens. (2) Since bone marrow specimens were prepared at or near the steady state of micronuclei, one sampling covered most chemicals with different actions. (3) For chemicals having multiple-dosing effects the recommended regimen was better than the protocol using 4 doses, because specimens could be prepared before the suppression of the bone marrow became excessive. (4) Chemicals having no multiple-dosing effect showed similar incidences of micronuclei after single and double dosing. (5) Dose selection is easier than with more multiple dosing, because, e.g., 50, 25, and 12.5% of LD50 values determined on single dosing will usually be tolerated by test animals. The detection spectrum would become wider if specimens are also prepared 48 h after the second dosing for metabolic inhibitors, base analogues, and the other chemicals which might show delayed activities.","Single versus multiple dosing in the micronucleus test: The summary of the fourth collaborative study by CSGMT/JEMS.MMS Abs: The effects of multiple dosing in the micronucleus test were studied by treating male CD-1 mice 1, 2, and 4 times i.p. with various doses of 11 chemicals and by sampling bone marrow cells 6, 24, 48, and/or 72 h after the final dosing. The chemicals used were 2-acetylaminofluorene (2-AAF), 1-beta-D-arabinofuranosylcytosine (ARA-C), 7,12-dimethylbenz[a]anthracene (DMBA), ethyl methanesulfonate (EMS), N-ethyl-N-nitrosourea (ENU), 6-mercaptopurine (6-MP), phenacetin (PHEN), 5-fluorouracil (5-FU), methotrexate (MTX), benzene (BEN), and potassium chromate (K2CrO4). MTX, an inhibitor of nucleotide synthesis, was a weak micronucleus inducer after single dosing, but clearly positive after multiple dosing. Although ARA-C, 5-FU, and 6-MP became positive after single dosing, the multiple dosing enhanced the effects of these base analogues. ENU, DMBA, and BEN, at some doses and sampling times, also showed increased responses by multiple dosing, but a severe trade-off occurred enhanced toxicity tended to reduce the bone marrow cells, especially at 4 dosings, making the examination of micronuclei difficult. PHEN showed the multiple-dosing effect after 2 doses, but the effect disappeared at quadruple dosing. No apparent multiple-dosing effects were observed with 2-AAF, EMS, and K2CrO4, which gave similar incidences of micronuclei after single and double dosing. The original double dosing and sampling 6 h after the second injection method of Schmid (1975) was less sensitive than the modified method, i.e., sampling 24 h after the second dosing. The latter regimen is recommended for the general screening for the following reasons. (1) It was the most sensitive protocol among those tested here and detected all test chemicals as clastogens. (2) Since bone marrow specimens were prepared at or near the steady state of micronuclei, one sampling covered most chemicals with different actions. (3) For chemicals having multiple-dosing effects the recommended regimen was better than the protocol using 4 doses, because specimens could be prepared before the suppression of the bone marrow became excessive. (4) Chemicals having no multiple-dosing effect showed similar incidences of micronuclei after single and double dosing. (5) Dose selection is easier than with more multiple dosing, because, e.g., 50, 25, and 12.5% of LD50 values determined on single dosing will usually be tolerated by test animals. The detection spectrum would become wider if specimens are also prepared 48 h after the second dosing for metabolic inhibitors, base analogues, and the other chemicals which might show delayed activities."
1234742,Wood et al. 1990,Acute dichromate poisoning after use of traditional purgatives. A report of 7 cases,"Seven cases of dichromate poisoning after the use of purgative solutions obtained from nyanga (traditional township healers) are reported. The patients all presented in established renal failure requiring dialysis, and all had abnormal liver function tests. One patient who took dichromate orally died from massive gastro-intestinal haemorrhage. Six patients took dichromate solutions as rectal enemas, 2 were left with impaired renal function and 1 required a permanent colostomy as a result of extensive peri-anal necrosis. The clinical presentation of acute renal failure, gastro-intestinal haemorrhage and hepatocellular dysfunction should alert the physician to the possibility of dichromate poisoning. The diagnosis, management and the role of dialysis in dichromate poisoning are reviewed.","Acute dichromate poisoning after use of traditional purgatives. A report of 7 cases Abs: Seven cases of dichromate poisoning after the use of purgative solutions obtained from nyanga (traditional township healers) are reported. The patients all presented in established renal failure requiring dialysis, and all had abnormal liver function tests. One patient who took dichromate orally died from massive gastro-intestinal haemorrhage. Six patients took dichromate solutions as rectal enemas, 2 were left with impaired renal function and 1 required a permanent colostomy as a result of extensive peri-anal necrosis. The clinical presentation of acute renal failure, gastro-intestinal haemorrhage and hepatocellular dysfunction should alert the physician to the possibility of dichromate poisoning. The diagnosis, management and the role of dialysis in dichromate poisoning are reviewed."
1234741,Forsythe 1990,The rapid detection of direct-acting DNA mutagens by electrical impedence with a DNA repair-deficient strain of Escherichia coli,"A differential killing assay using Escherichia coli WP2 (wild type) and WP67 (uvrA, polA) was combined with impedence microbiology to produce a rapid screening method for direct-acting mutagenic compounds. The assay showed that mitomycin C, N-nitroso guanidine, potassium dichromate, sodium azide and acridine orange were direct-acting mutagens. With this method results can be obtained within hours, as compared with two days for the standard Salmonella/microsome test.","The rapid detection of direct-acting DNA mutagens by electrical impedence with a DNA repair-deficient strain of Escherichia coli Abs: A differential killing assay using Escherichia coli WP2 (wild type) and WP67 (uvrA, polA) was combined with impedence microbiology to produce a rapid screening method for direct-acting mutagenic compounds. The assay showed that mitomycin C, N-nitroso guanidine, potassium dichromate, sodium azide and acridine orange were direct-acting mutagens. With this method results can be obtained within hours, as compared with two days for the standard Salmonella/microsome test."
1234738,Sato et al. 1990,A comparison of micronucleus induction in 3 mouse strains with representative clastogens,"The frequency of micronucleated polychromatic erythrocytes (MNPCEs) was compared in BALB/c, C57BL/6 and DBA/2 mice after the intraperitoneal injection (i.p.) of methyl methanesulfonate (MMS), potassium chromate (K2CrO4), colchicine (COL), cycloheximide (CYH), 4-nitroquinoline-1-oxide (4-NQO) and 5-fluorouracil (5-FU). In BALB/c mice, the frequency of MNPCEs was significantly increased by all the chemicals tested, as compared to the vehicle control. In both C57BL/6 and DBA/2 mice, MMS, K2CrO4, COL and 4-NQO significantly increased MNPCEs, but CYH and 5-FU only slightly increased the MNPCEs in C57BL/6 and had no effect on DBA/2 mice. These results suggest that BALB/c mice are more sensitive to the induction of MNPCEs with a wider spectrum of chemicals than C57BL/6 or DBA/2 mice.","A comparison of micronucleus induction in 3 mouse strains with representative clastogens Abs: The frequency of micronucleated polychromatic erythrocytes (MNPCEs) was compared in BALB/c, C57BL/6 and DBA/2 mice after the intraperitoneal injection (i.p.) of methyl methanesulfonate (MMS), potassium chromate (K2CrO4), colchicine (COL), cycloheximide (CYH), 4-nitroquinoline-1-oxide (4-NQO) and 5-fluorouracil (5-FU). In BALB/c mice, the frequency of MNPCEs was significantly increased by all the chemicals tested, as compared to the vehicle control. In both C57BL/6 and DBA/2 mice, MMS, K2CrO4, COL and 4-NQO significantly increased MNPCEs, but CYH and 5-FU only slightly increased the MNPCEs in C57BL/6 and had no effect on DBA/2 mice. These results suggest that BALB/c mice are more sensitive to the induction of MNPCEs with a wider spectrum of chemicals than C57BL/6 or DBA/2 mice."
1234737,Decaestecker et al. 1990,Hypersensitivity to dichromate among asymptomatic workers in a chromate pigment factory,"A study of chromium (7440473) sensitivity was conducted in 29 asymptomatic men who worked in a chromate (13907454) pigment factory (SIC-2816). Patch testing was performed with 0.5% potassium-dichromate (7778509), 0.1% cobalt-chloride (7646799) and 5% nickel-sulfate (7786814) in petrolatum. The patches were applied at the end of the work week on Friday afternoon and removed 48 hours later. They were read immediately after being removed and 24 hours later. Six subjects showed positive responses to potassium-dichromate and six to nickel-sulfate. Three of these showed positive responses to both. Two other subjects showed positive reactions to cobalt-chloride. The authors conclude that the observed sensitization to chromate, nickel (7440020), and cobalt (7440484) in the subjects is much higher than in the general population. The cellular basis for metal induced hypersensitivity was discussed.","Hypersensitivity to dichromate among asymptomatic workers in a chromate pigment factory Abs: A study of chromium (7440473) sensitivity was conducted in 29 asymptomatic men who worked in a chromate (13907454) pigment factory (SIC-2816). Patch testing was performed with 0.5% potassium-dichromate (7778509), 0.1% cobalt-chloride (7646799) and 5% nickel-sulfate (7786814) in petrolatum. The patches were applied at the end of the work week on Friday afternoon and removed 48 hours later. They were read immediately after being removed and 24 hours later. Six subjects showed positive responses to potassium-dichromate and six to nickel-sulfate. Three of these showed positive responses to both. Two other subjects showed positive reactions to cobalt-chloride. The authors conclude that the observed sensitization to chromate, nickel (7440020), and cobalt (7440484) in the subjects is much higher than in the general population. The cellular basis for metal induced hypersensitivity was discussed."
1234736,Fan and  Zhao 1990,Study on Chinese common allergens of contact dermatitis,"Patch tests were performed according to the European Standard Allergens (ESA) in 204 cases suspected of contact dermatitis. The reaction was positive in 58.33% of the cases. The common allergens were nickel (15.7%), fragrance mix (11.8%) p-phenylenediamine (8.8%), colophony (6.9%), benzocaine (6.4%), formaldehyde (5.9%), black rubber mix (4.9%), cobalt (4.4%), balsam of Peru (3.9%), potassium dichromate (3.4%), thiuram mix (2.9%) and mercapto mix (2.9%). In 85 cases of negative reaction to the European Standard Allergens, 36 were patch tested to suspected agents based on the individual case histories, of which 21 positively reacted. The common sensitizing agents were ampicillin and thiomersal. Of 204 cases, 107 were cases of facial contact dermatitis. Patch tests showed that the most common allergens were p-phenylenediamine (15.9%), nickel (13.1%) and fragrance mix (14.95%).","Study on Chinese common allergens of contact dermatitis Abs: Patch tests were performed according to the European Standard Allergens (ESA) in 204 cases suspected of contact dermatitis. The reaction was positive in 58.33% of the cases. The common allergens were nickel (15.7%), fragrance mix (11.8%) p-phenylenediamine (8.8%), colophony (6.9%), benzocaine (6.4%), formaldehyde (5.9%), black rubber mix (4.9%), cobalt (4.4%), balsam of Peru (3.9%), potassium dichromate (3.4%), thiuram mix (2.9%) and mercapto mix (2.9%). In 85 cases of negative reaction to the European Standard Allergens, 36 were patch tested to suspected agents based on the individual case histories, of which 21 positively reacted. The common sensitizing agents were ampicillin and thiomersal. Of 204 cases, 107 were cases of facial contact dermatitis. Patch tests showed that the most common allergens were p-phenylenediamine (15.9%), nickel (13.1%) and fragrance mix (14.95%)."
1234732,Tanii et al. 1991,A case of prurigo pigmentosa considered to be contact allergy to chromium in an acupuncture needle,"A 53-year-old male developed prurigo pigmentosa on his back, after undergoing acupuncture for 3 years. The eruptions were ceased on discontinuing the therapy but recurred with its resumption. The acupuncture needle contained 18.12% chromium. Erythema was induced by patch testing with potassium dichromate, and a flare-up was observed in the area of the patch test on resumption of acupuncture. We consider that the eruptions were induced by contact allergy to the chromium component of the acupuncture needles.","A case of prurigo pigmentosa considered to be contact allergy to chromium in an acupuncture needle Abs: A 53-year-old male developed prurigo pigmentosa on his back, after undergoing acupuncture for 3 years. The eruptions were ceased on discontinuing the therapy but recurred with its resumption. The acupuncture needle contained 18.12% chromium. Erythema was induced by patch testing with potassium dichromate, and a flare-up was observed in the area of the patch test on resumption of acupuncture. We consider that the eruptions were induced by contact allergy to the chromium component of the acupuncture needles."
1234731,Abraham et al. 1991,Chromium and cholesterol-induced atherosclerosis in rabbits,"Thirty-three rabbits on a cholesterol-enriched diet were randomized into 6 groups and treated with daily injections of either water, 20 micrograms of potassium chromate or 1, 5, 10 or 20 micrograms of chromium chloride, respectively, for 135 days with a 2- to 10-fold increase in serum chromium. There was a marked reduction in the percentage of aortic intimal surface covered by plaque, in aortic weight and cholesterol content in the treated animals. Rabbits treated with 20 micrograms of chromium chloride showed a better response than those treated with either 10 or 20 micrograms of potassium chromate.","Chromium and cholesterol-induced atherosclerosis in rabbits Abs: Thirty-three rabbits on a cholesterol-enriched diet were randomized into 6 groups and treated with daily injections of either water, 20 micrograms of potassium chromate or 1, 5, 10 or 20 micrograms of chromium chloride, respectively, for 135 days with a 2- to 10-fold increase in serum chromium. There was a marked reduction in the percentage of aortic intimal surface covered by plaque, in aortic weight and cholesterol content in the treated animals. Rabbits treated with 20 micrograms of chromium chloride showed a better response than those treated with either 10 or 20 micrograms of potassium chromate."
1234729,Picaud et al. 1991,Acute renal failure in a child after chewing of match heads,"A few days after ingestion of 40 match heads, a 3-year-old boy was admitted to hospital with oliguric acute renal failure (ARF) requiring peritoneal dialysis during 9 days. A renal biopsy showed acute tubulointerstitial nephritis; the outcome was rapidly favorable and the child recovered normal GFR. It seems to be the first published case of ARF after match poisoning, probably because of the presence of potassium bichromate.","Acute renal failure in a child after chewing of match heads Abs: A few days after ingestion of 40 match heads, a 3-year-old boy was admitted to hospital with oliguric acute renal failure (ARF) requiring peritoneal dialysis during 9 days. A renal biopsy showed acute tubulointerstitial nephritis; the outcome was rapidly favorable and the child recovered normal GFR. It seems to be the first published case of ARF after match poisoning, probably because of the presence of potassium bichromate."
1234728,Faria and  Witmer 1991,Mixed function oxidase enzyme responses to in vivo and in vitro chromate treatment,"Chromium (Cr) is an essential nutrient in humans which aids in the metabolism of cholesterol, glucose and fats. The trivalent state (Cr(III)) is essential in trace doses, while Cr(VI) is toxic to mammals in acute and subchronic doses [Langard and Norseth, 1986] and long term exposure has been associated with respiratory cancer [Chiazze and Wolf, 1980; Langard and Norseth, 1975; Mancuso, 1975]. Unusually high rates of lung cancer have been reported in workers in chrome plating, leather tanning, and other Cr related industries [Chiazze and Wolf, 1980; Langard and Norseth, 1975; Mancuso, 1975]. The mechanisms for the toxic and genotoxic effects of Cr are only partially understood. The differences in toxicity of the two most common oxidation states, Cr(VI) and Cr(III), are due to the relative lack of ability of cationic Cr(III) compounds to cross cell membranes, while Cr(VI) as the chromate anion, crosses biological membranes freely [Aaseth et al., 1982; Wiegand et al., 1985]. The intracellular reduction of Cr(VI) has recently been shown to result in both Cr(V) and Cr(III) production, both of which are putative DNA damaging agents [Goodgame et al., 1982; Jennette, 1982]. Compounds such as glutathione (GSH) [Aaseth et al., 1982; Connett and Wetterhahn, 1983], ascorbate [Connett and Wetterhahn, 1983], and hydrogen peroxide [Cupo and Wetterhahn, 1985] participate in the intracellular reduction of Cr(VI). Reduction takes place both in mitochondria [Alexander et al., 1982], and the endoplasmic reticulum [Gruber and Jennette, 1978]. When GSH is the reductant a toxic glutathionyl radical (GS) may be formed [Wetterhahn, 1990, in press]. Cr(III) binds to nucleophiles including some sulfhydryl (SH) containing enzymes, with some resulting enzyme inhibition. Thus the metabolism of Cr(VI) is important for the interaction of Cr with DNA [Tsapakos and Wetterhahn, 1983], with GSH [Wiegand et al., 1985] and with SH groups on other cellular macromolecules. Previous studies with microsomes have indicated that cytochrome P-450 (P-450), an SH containing enzyme, acts as an electron donor in the microsomal reduction of Cr(VI) [Gruber and Jennette, 1978].","Mixed function oxidase enzyme responses to in vivo and in vitro chromate treatment Abs: Chromium (Cr) is an essential nutrient in humans which aids in the metabolism of cholesterol, glucose and fats. The trivalent state (Cr(III)) is essential in trace doses, while Cr(VI) is toxic to mammals in acute and subchronic doses [Langard and Norseth, 1986] and long term exposure has been associated with respiratory cancer [Chiazze and Wolf, 1980; Langard and Norseth, 1975; Mancuso, 1975]. Unusually high rates of lung cancer have been reported in workers in chrome plating, leather tanning, and other Cr related industries [Chiazze and Wolf, 1980; Langard and Norseth, 1975; Mancuso, 1975]. The mechanisms for the toxic and genotoxic effects of Cr are only partially understood. The differences in toxicity of the two most common oxidation states, Cr(VI) and Cr(III), are due to the relative lack of ability of cationic Cr(III) compounds to cross cell membranes, while Cr(VI) as the chromate anion, crosses biological membranes freely [Aaseth et al., 1982; Wiegand et al., 1985]. The intracellular reduction of Cr(VI) has recently been shown to result in both Cr(V) and Cr(III) production, both of which are putative DNA damaging agents [Goodgame et al., 1982; Jennette, 1982]. Compounds such as glutathione (GSH) [Aaseth et al., 1982; Connett and Wetterhahn, 1983], ascorbate [Connett and Wetterhahn, 1983], and hydrogen peroxide [Cupo and Wetterhahn, 1985] participate in the intracellular reduction of Cr(VI). Reduction takes place both in mitochondria [Alexander et al., 1982], and the endoplasmic reticulum [Gruber and Jennette, 1978]. When GSH is the reductant a toxic glutathionyl radical (GS) may be formed [Wetterhahn, 1990, in press]. Cr(III) binds to nucleophiles including some sulfhydryl (SH) containing enzymes, with some resulting enzyme inhibition. Thus the metabolism of Cr(VI) is important for the interaction of Cr with DNA [Tsapakos and Wetterhahn, 1983], with GSH [Wiegand et al., 1985] and with SH groups on other cellular macromolecules. Previous studies with microsomes have indicated that cytochrome P-450 (P-450), an SH containing enzyme, acts as an electron donor in the microsomal reduction of Cr(VI) [Gruber and Jennette, 1978]."
1234727,Cingi et al. 1991,Choice and standardization of test protocols in cytotoxicology: A multicentre approach,"A major problem that interferes with the introduction of in vitro tests for toxicological risk assessment is that of defining reliable standardized protocols. This issue was approached in the present study with an interlaboratory comparison of three cytotoxicity assays detecting chemical toxicity as impairment of cell viability in confluent cultures, reduction of colony forming ability, and inhibition of cell proliferation over 3 days of treatment. The study was performed using V79 cells, which are unable to activate indirectly-acting xenobiotics, and six chemicals with different mechanisms of action: two antioxidants (butylated hydroxyanisole and butylated hydroxytoluene), an inhibitor of protein synthesis (cycloheximide), an alkylating agent requiring metabolic activation (cyclophosphamide), an uncoupler of oxidative phosphorylation (dinitrophenol), and a genotoxic metal salt (potassium dichromate). The three tests produced the same rank of relative toxic potency for the tested chemicals, based on LC(50) values. The cell viability test appeared to be the most suited for the screening of unknown chemicals, given its simplicity and better reproducibility.","Choice and standardization of test protocols in cytotoxicology: A multicentre approach Abs: A major problem that interferes with the introduction of in vitro tests for toxicological risk assessment is that of defining reliable standardized protocols. This issue was approached in the present study with an interlaboratory comparison of three cytotoxicity assays detecting chemical toxicity as impairment of cell viability in confluent cultures, reduction of colony forming ability, and inhibition of cell proliferation over 3 days of treatment. The study was performed using V79 cells, which are unable to activate indirectly-acting xenobiotics, and six chemicals with different mechanisms of action: two antioxidants (butylated hydroxyanisole and butylated hydroxytoluene), an inhibitor of protein synthesis (cycloheximide), an alkylating agent requiring metabolic activation (cyclophosphamide), an uncoupler of oxidative phosphorylation (dinitrophenol), and a genotoxic metal salt (potassium dichromate). The three tests produced the same rank of relative toxic potency for the tested chemicals, based on LC(50) values. The cell viability test appeared to be the most suited for the screening of unknown chemicals, given its simplicity and better reproducibility."
1234726,Andreoli et al. 1991,Evaluation of metabolic endpoints of acute cytotoxicity in V79 fibroblasts,"A group of cytotoxicity tests that detect alterations in cell metabolism were applied to obtain a preliminary classification of test chemicals, based on their main mechanism of toxicity. V79 cells were exposed to toxic compounds in 'acute' treatments (up to 2 hr) and the specificity of different endpoints of cytotoxicity was compared. We tested five directly acting chemicals: butylated hydroxyanisole, butylated hydroxytoluene, cycloheximide, potassium dichromate [Cr(VI)] and dinitrophenol using four assays measuring; [(3)H]thymidine uptake and incorporation into DNA, [(3)H]leucine incorporation into proteins, ATP pool size and cellular energy charge, and oxygen consumption. In the thymidine-uptake test the radioactivity of the nucleotide pool was hardly affected by low concentrations of the toxic chemicals and was reduced by about 20-30% at the 10(-4)m concentration, except by butylated hydroxytoluene; the latter which caused a marked inhibition of [(3)H]thymidine uptake. Thymidine incorporation into DNA was more specifically altered, showing a net inhibition by potassium dichromate, in a concentration-dependent fashion, and by butylated hydroxytoluene. Protein synthesis was more inhibited by potassium dichromate and butylated hydroxytoluene than by the specific inhibitor, cycloheximide. All chemicals reduced ATP concentration, but the energy charge was scarcely affected, reflecting a parallel decrease of the other adenine nucleotides. The assay measuring early changes in oxygen consumption produced the expected results with dinitrophenol, the antioxidants and potassium dichromate, and showed that cycloheximide also inhibits mitochondrial respiration, in agreement with the observed fall of intracellular ATP. All the chemicals tested induced a range of effects on the metabolic parameters analysed but specific pathways of toxicity may be inferred by comparing the results of the individual tests.","Evaluation of metabolic endpoints of acute cytotoxicity in V79 fibroblasts Abs: A group of cytotoxicity tests that detect alterations in cell metabolism were applied to obtain a preliminary classification of test chemicals, based on their main mechanism of toxicity. V79 cells were exposed to toxic compounds in 'acute' treatments (up to 2 hr) and the specificity of different endpoints of cytotoxicity was compared. We tested five directly acting chemicals: butylated hydroxyanisole, butylated hydroxytoluene, cycloheximide, potassium dichromate [Cr(VI)] and dinitrophenol using four assays measuring; [(3)H]thymidine uptake and incorporation into DNA, [(3)H]leucine incorporation into proteins, ATP pool size and cellular energy charge, and oxygen consumption. In the thymidine-uptake test the radioactivity of the nucleotide pool was hardly affected by low concentrations of the toxic chemicals and was reduced by about 20-30% at the 10(-4)m concentration, except by butylated hydroxytoluene; the latter which caused a marked inhibition of [(3)H]thymidine uptake. Thymidine incorporation into DNA was more specifically altered, showing a net inhibition by potassium dichromate, in a concentration-dependent fashion, and by butylated hydroxytoluene. Protein synthesis was more inhibited by potassium dichromate and butylated hydroxytoluene than by the specific inhibitor, cycloheximide. All chemicals reduced ATP concentration, but the energy charge was scarcely affected, reflecting a parallel decrease of the other adenine nucleotides. The assay measuring early changes in oxygen consumption produced the expected results with dinitrophenol, the antioxidants and potassium dichromate, and showed that cycloheximide also inhibits mitochondrial respiration, in agreement with the observed fall of intracellular ATP. All the chemicals tested induced a range of effects on the metabolic parameters analysed but specific pathways of toxicity may be inferred by comparing the results of the individual tests."
1234724,Miller et al. 1991,Complexing of actin and other nuclear proteins to DNA by cis-diamminedichloroplatinum(II) and chromium compounds,"Actin was found to be the major protein crosslinked to the DNA of intact Chinese hamster ovary cells that were treated with either potassium chromate (hexavalent) or cis-diamminedichloroplatinum(II) (cis-platinum). This protein was identified as actin by its mol. wt (45 kd), its isoelectric point (pI = 5.4), positive reactivity with an actin antibody, and by protease mapping. Additionally, a purified actin standard migrated to the same location in a two-dimensional gel system as p45. Actin comprised approximately 20% of the protein component in chromate-induced DNA-protein crosslinks. In addition, to actin, several other major proteins (e.g. 53 kd, pI = 5.2, 50 kd, pI = 9) were crosslinked to DNA following exposure to cis-platinum or chromate. These proteins were abundant in the nuclear matrix fraction. Hexavalent chromate is the toxicologically active form because it is readily taken up into cells by an anion transport system. In contrast, trivalent chromium is considerably less toxic because it cannot enter the cell; however, most of the hexavalent form is eventually reduced to the trivalent form inside the cell. Previous studies have suggested that the trivalent form of chromium participates in complexing DNA with proteins. DNA-protein crosslinks were formed in isolated nuclei or in mixtures of purified DNA and protein incubated with trivalent chromium. However, the formation of these complexes required at least 16 h of incubation to exchange the parent compound ligands. Hexavalent chromate did not form these complexes in vitro under similar conditions. Incubation of trivalent chromium with purified actin and DNA resulted in DNA-actin crosslinks as detected by an electrophoretic mobility different from that of either free actin or DNA when the complex was transferred from a gel to nitrocellulose and stained for protein. These studies describe a new technique for detecting DNA-protein complexes and demonstrate that actin-DNA structures in intact cells create sites that selectively react with metal DNA-protein crosslinking agents.","Complexing of actin and other nuclear proteins to DNA by cis-diamminedichloroplatinum(II) and chromium compounds Abs: Actin was found to be the major protein crosslinked to the DNA of intact Chinese hamster ovary cells that were treated with either potassium chromate (hexavalent) or cis-diamminedichloroplatinum(II) (cis-platinum). This protein was identified as actin by its mol. wt (45 kd), its isoelectric point (pI = 5.4), positive reactivity with an actin antibody, and by protease mapping. Additionally, a purified actin standard migrated to the same location in a two-dimensional gel system as p45. Actin comprised approximately 20% of the protein component in chromate-induced DNA-protein crosslinks. In addition, to actin, several other major proteins (e.g. 53 kd, pI = 5.2, 50 kd, pI = 9) were crosslinked to DNA following exposure to cis-platinum or chromate. These proteins were abundant in the nuclear matrix fraction. Hexavalent chromate is the toxicologically active form because it is readily taken up into cells by an anion transport system. In contrast, trivalent chromium is considerably less toxic because it cannot enter the cell; however, most of the hexavalent form is eventually reduced to the trivalent form inside the cell. Previous studies have suggested that the trivalent form of chromium participates in complexing DNA with proteins. DNA-protein crosslinks were formed in isolated nuclei or in mixtures of purified DNA and protein incubated with trivalent chromium. However, the formation of these complexes required at least 16 h of incubation to exchange the parent compound ligands. Hexavalent chromate did not form these complexes in vitro under similar conditions. Incubation of trivalent chromium with purified actin and DNA resulted in DNA-actin crosslinks as detected by an electrophoretic mobility different from that of either free actin or DNA when the complex was transferred from a gel to nitrocellulose and stained for protein. These studies describe a new technique for detecting DNA-protein complexes and demonstrate that actin-DNA structures in intact cells create sites that selectively react with metal DNA-protein crosslinking agents."
1234723,Kimber et al. 1991,The murine local lymph node assay: results of an inter-laboratory trial,"The local lymph node assay is a novel predictive test for the identification of contact allergens. The collaborative study reported here was performed to evaluate the reliability of the method when performed in independent laboratories. Eight chemicals were examined in each of 4 participating laboratories and results compared with predictions of skin-sensitizing activity made from concurrent Magnusson and Kligman guinea-pig maximization tests performed in a single laboratory. The local lymph node assay has as its theoretical basis the fact that contact allergens induce T-lymphocyte proliferative responses. In practice, predictions of contact-sensitizing potential are made following measurement of proliferation in lymph nodes draining the site of exposure to chemical, and derivation of a stimulation index using control values as the comparator. Although in the present study there was some variation between laboratories with respect to the absolute stimulation indices recorded, it was found that with all chemicals each laboratory made the same predictions of sensitizing activity. Six chemicals (2,4-dinitrochlorobenzene, formalin, eugenol, isoeugenol, p-phenylenediamine and potassium dichromate) yielded positive responses, and two (methyl salicylate and benzocaine) were negative, in each laboratory. Furthermore, with 7 of the 8 chemicals tested there was no significant difference between laboratories in terms of the characteristics of the dose-response relationships recorded. With the exception of one chemical (benzocaine), predictions made with the local lymph node assay were in accord with those derived from guinea-pig maximization tests. These inter-laboratory comparisons demonstrate that the local lymph node assay is a robust and reliable method for the identification of at least moderate and strong contact allergens.","The murine local lymph node assay: results of an inter-laboratory trial Abs: The local lymph node assay is a novel predictive test for the identification of contact allergens. The collaborative study reported here was performed to evaluate the reliability of the method when performed in independent laboratories. Eight chemicals were examined in each of 4 participating laboratories and results compared with predictions of skin-sensitizing activity made from concurrent Magnusson and Kligman guinea-pig maximization tests performed in a single laboratory. The local lymph node assay has as its theoretical basis the fact that contact allergens induce T-lymphocyte proliferative responses. In practice, predictions of contact-sensitizing potential are made following measurement of proliferation in lymph nodes draining the site of exposure to chemical, and derivation of a stimulation index using control values as the comparator. Although in the present study there was some variation between laboratories with respect to the absolute stimulation indices recorded, it was found that with all chemicals each laboratory made the same predictions of sensitizing activity. Six chemicals (2,4-dinitrochlorobenzene, formalin, eugenol, isoeugenol, p-phenylenediamine and potassium dichromate) yielded positive responses, and two (methyl salicylate and benzocaine) were negative, in each laboratory. Furthermore, with 7 of the 8 chemicals tested there was no significant difference between laboratories in terms of the characteristics of the dose-response relationships recorded. With the exception of one chemical (benzocaine), predictions made with the local lymph node assay were in accord with those derived from guinea-pig maximization tests. These inter-laboratory comparisons demonstrate that the local lymph node assay is a robust and reliable method for the identification of at least moderate and strong contact allergens."
1234722,Massone et al. 1991,"Positive patch test reactions to nickel, cobalt, and potassium dichromate in a series of 576 patients","In 1988, 633 patients attending our Allergology Center underwent patch testing with the standard series recommended by the Gruppo Italiano Ricerca Dermatiti da Contatto e Ambientali. Of these, 576 patients completed the test correctly and their results were evaluated statistically. Nickel, cobalt, and potassium dichromate were the three most common sensitizers; concomitant positive reactions were present at significant levels. The authors discuss environmental and occupational exposure to contact allergens and correlate the major sites of dermatitis with the sensitivity to each metal in patients of both sexes.","Positive patch test reactions to nickel, cobalt, and potassium dichromate in a series of 576 patients Abs: In 1988, 633 patients attending our Allergology Center underwent patch testing with the standard series recommended by the Gruppo Italiano Ricerca Dermatiti da Contatto e Ambientali. Of these, 576 patients completed the test correctly and their results were evaluated statistically. Nickel, cobalt, and potassium dichromate were the three most common sensitizers; concomitant positive reactions were present at significant levels. The authors discuss environmental and occupational exposure to contact allergens and correlate the major sites of dermatitis with the sensitivity to each metal in patients of both sexes."
1234721,Shehade et al. 1991,Epidemiological survey of standard series patch test results and observations on day 2 and day 4 readings,"Computer data on 4721 consecutive patients patch tested with an extended standard series were analysed for the frequency of allergic reactions to each substance. Particular attention was given to the negative first reading at day 2 (D2) which later became positive at day 4 (D4). A total of 4210 allergic reactions were recorded. 993 of which were negative on D2 (24%). The most frequent positive reactions were to nickel sulphate (18%), fragrance-mix (8%), colophony (6%), neomycin (6%), cobalt chloride (6%), thiuram-mix (4%) and potassium dichromate (3%). The frequency of negative D2, positive D4 readings was sizeable for all but one substance, primin, with a range of 14% for fragrance-mix to 64% for neomycin. All of 21 positive reactions to primin were recorded on D2. In our opinion, it is unjustified to perform D2-only patch test readings.","Epidemiological survey of standard series patch test results and observations on day 2 and day 4 readings Abs: Computer data on 4721 consecutive patients patch tested with an extended standard series were analysed for the frequency of allergic reactions to each substance. Particular attention was given to the negative first reading at day 2 (D2) which later became positive at day 4 (D4). A total of 4210 allergic reactions were recorded. 993 of which were negative on D2 (24%). The most frequent positive reactions were to nickel sulphate (18%), fragrance-mix (8%), colophony (6%), neomycin (6%), cobalt chloride (6%), thiuram-mix (4%) and potassium dichromate (3%). The frequency of negative D2, positive D4 readings was sizeable for all but one substance, primin, with a range of 14% for fragrance-mix to 64% for neomycin. All of 21 positive reactions to primin were recorded on D2. In our opinion, it is unjustified to perform D2-only patch test readings."
1234720,Bajaj et al. 1991,Shoe dermatitis in India: further observations,,Shoe dermatitis in India: further observations Abs: 
1234719,Michie et al. 1991,Poisoning with a traditional remedy containing potassium dichromate,"A fatal case of potassium dichromate ingestion is documented. A retrospective review of serum and organ levels of chromium demonstrates that charcoal haemoperfusion, peritoneal and haemodialysis are ineffective therapies for the toxin. Other treatments for this poisoning are reviewed, the poor prognosis of dichromate ingestion, and the paucity of effective therapy underlined. The application of dichromates in traditional medications is briefly discussed; this is a toxin which may be more prevalent than previously thought. It is proposed that the exposure limits of dichromate be more widely publicised.","Poisoning with a traditional remedy containing potassium dichromate Abs: A fatal case of potassium dichromate ingestion is documented. A retrospective review of serum and organ levels of chromium demonstrates that charcoal haemoperfusion, peritoneal and haemodialysis are ineffective therapies for the toxin. Other treatments for this poisoning are reviewed, the poor prognosis of dichromate ingestion, and the paucity of effective therapy underlined. The application of dichromates in traditional medications is briefly discussed; this is a toxin which may be more prevalent than previously thought. It is proposed that the exposure limits of dichromate be more widely publicised."
1234718,Hosokawa et al. 1991,"Influence of sulfate, Ca, and Mg on the acute toxicity of potassium dichromate to Daphnia similis",,"Influence of sulfate, Ca, and Mg on the acute toxicity of potassium dichromate to Daphnia similis Abs: "
1234717,Hery et al. 1991,Assessment of the performance of respirators in the workplace,"The efficiency of a mask currently used in an inorganic pigment manufacturing plant producing suspected carcinogens was assessed and the protection provided by it was found to be insufficient. Three other masks, with better laboratory performances, were tested in field conditions. None of them reduced personal exposures to below the French limit values, and their performance in the field was well below that in laboratory assessments. A similar study in another pigment manufacturing plant gave similar results. Possibly only power-assisted filtering devices will provide satisfactory working conditions.","Assessment of the performance of respirators in the workplace Abs: The efficiency of a mask currently used in an inorganic pigment manufacturing plant producing suspected carcinogens was assessed and the protection provided by it was found to be insufficient. Three other masks, with better laboratory performances, were tested in field conditions. None of them reduced personal exposures to below the French limit values, and their performance in the field was well below that in laboratory assessments. A similar study in another pigment manufacturing plant gave similar results. Possibly only power-assisted filtering devices will provide satisfactory working conditions."
1234716,Sanz et al. 1991,Acute potassium dichromate poisoning,BIOSIS COPYRIGHT: BIOL ABS. RRM NOTE HUMAN VOMITING DIARRHEA RENAL FAILURE,Acute potassium dichromate poisoning Abs: BIOSIS COPYRIGHT: BIOL ABS. RRM NOTE HUMAN VOMITING DIARRHEA RENAL FAILURE
1234715,Snyder and  Valle 1991,Immune function assays as indicators of chromate exposure,"The potential immunomodulatory effects of chromium were investigated using a series of in vitro and in vivo studies. Chromium (as K2CrO4) in concentrations spanning five orders of magnitude was added in vitro to T-lymphocyte (concanavalin A) and B-lymphocyte (liposaccharide) mitogen cultures and was found to inhibit T-lymphocyte responses at all concentrations tested and to inhibit B-lymphocyte responses at all but the lowest concentration tested (0.01 mg/L). When the same concentrations of chromium were employed in mixed lymphocyte cultures, antigen-induced thymidine uptake was inhibited at the highest concentrations (100 mg/L-1 mg/L), enhanced at 0.1 mg/L, and equal to control values at lower concentrations. Splenocytes isolated from rats exposed to K2CrO4 in drinking water exhibited enhanced responses to T- and B-lymphocyte mitogens. The addition of 0.1 mg/L of chromium to a mixed lymphocyte culture containing splenocytes taken from chromium-exposed rats increased by 5-fold the uptake of thymidine by these cells. These increased responses of cells from chromium-exposed rats may indicate chromium-induced sensitization and may possibly be used as a biological marker for chromium exposure.","Immune function assays as indicators of chromate exposure Abs: The potential immunomodulatory effects of chromium were investigated using a series of in vitro and in vivo studies. Chromium (as K2CrO4) in concentrations spanning five orders of magnitude was added in vitro to T-lymphocyte (concanavalin A) and B-lymphocyte (liposaccharide) mitogen cultures and was found to inhibit T-lymphocyte responses at all concentrations tested and to inhibit B-lymphocyte responses at all but the lowest concentration tested (0.01 mg/L). When the same concentrations of chromium were employed in mixed lymphocyte cultures, antigen-induced thymidine uptake was inhibited at the highest concentrations (100 mg/L-1 mg/L), enhanced at 0.1 mg/L, and equal to control values at lower concentrations. Splenocytes isolated from rats exposed to K2CrO4 in drinking water exhibited enhanced responses to T- and B-lymphocyte mitogens. The addition of 0.1 mg/L of chromium to a mixed lymphocyte culture containing splenocytes taken from chromium-exposed rats increased by 5-fold the uptake of thymidine by these cells. These increased responses of cells from chromium-exposed rats may indicate chromium-induced sensitization and may possibly be used as a biological marker for chromium exposure."
1234714,Ansari et al. 1991,The effects of potassium chromate and citrinin on rat renal membrane transport,"Both chromate and citrinin have been shown to produce acute renal damage. Although both substrates act on the proximal tubule in the rat, they affect different parts of that nephron segment. As with most nephrotoxicants, the mechanism(s) or subcellular target(s) for citrinin or chromate is unknow. The availability of methodology for isolation of functional membrane vesicles has afforded the opportunity to study the plasma membrane as a target for the effects of citrinin and chromate. Whether studied solely with in vitro conditions or after administration to the rat, chromate exhibited its primary action on the basolateral (BL) membrane vesicles. This was exhibited by a reduction in the p-aminohippurate (PAH) overhoot. At both 3 and 16 hr after treatment (40 mg/kg, sc) there was a significant, but relatively modest, effect on glucose transport by brush border (BB) vesicles. Citrinin, when studied in vitro, inhibited PAH transport (BL vesicles), but had only equivocal effects on BB glucose transport. However, after pretreatment of the rats with citrinin (60 mg/kg, ip), both BL and BB membrane vesicle function was reduced markedly at 3 hr. By 16 hr, an overshoot had returned for both transport substrates, although the glucose overshoot was still significantly below control. These data demonstrate that both citrinin and chromate alter proximal tubular cell membrane function and do so relatively early after administration to the rat. This effect suggests that alteration of membrane function by these nephrotoxicants is an early, if not initiating, event in the production of acute tubular necrosis.","The effects of potassium chromate and citrinin on rat renal membrane transport Abs: Both chromate and citrinin have been shown to produce acute renal damage. Although both substrates act on the proximal tubule in the rat, they affect different parts of that nephron segment. As with most nephrotoxicants, the mechanism(s) or subcellular target(s) for citrinin or chromate is unknow. The availability of methodology for isolation of functional membrane vesicles has afforded the opportunity to study the plasma membrane as a target for the effects of citrinin and chromate. Whether studied solely with in vitro conditions or after administration to the rat, chromate exhibited its primary action on the basolateral (BL) membrane vesicles. This was exhibited by a reduction in the p-aminohippurate (PAH) overhoot. At both 3 and 16 hr after treatment (40 mg/kg, sc) there was a significant, but relatively modest, effect on glucose transport by brush border (BB) vesicles. Citrinin, when studied in vitro, inhibited PAH transport (BL vesicles), but had only equivocal effects on BB glucose transport. However, after pretreatment of the rats with citrinin (60 mg/kg, ip), both BL and BB membrane vesicle function was reduced markedly at 3 hr. By 16 hr, an overshoot had returned for both transport substrates, although the glucose overshoot was still significantly below control. These data demonstrate that both citrinin and chromate alter proximal tubular cell membrane function and do so relatively early after administration to the rat. This effect suggests that alteration of membrane function by these nephrotoxicants is an early, if not initiating, event in the production of acute tubular necrosis."
1234712,Michael et al. 1991,The beneficial effects of thyroxine on nephrotoxic acute renal failure in the rat,"We were able to confirm previous studies demonstrating that administration of thyroxine is capable of ameliorating the severity of acute nephrotoxic renal failure in the rat. Nephrotoxic acute renal failure was induced by the subcutaneous injection of potassium dichromate (6.25 mg/kg) into Sprague-Dawley rats. Twenty-four hours after this injection, rats received an intraperitoneal injection of either thyroxine (80 micrograms/kg body wt) or normal saline. Forty-eight hours after the potassium dichromate injection, renal clearance studies were performed. Inulin clearance was significantly higher in the thyroxine-treated than in the saline-treated acute renal failure rats: 1.12 +/- 0.13 (SEM) mL/g versus 0.75 +/- 0.07 mL/min/g kidney wt (P = 0.025). Thyroxine treatment also effected an increase of p-aminohippuric acid extraction from 0.23 +/- 0.03 to 0.33 +/- 0.02 (P = 0.011) and a decrease in the fractional excretion of sodium from 0.38 +/- 0.21 to 0.11 +/- 0.03% (P = 0.037 by Mann-Whitney U test). In order to investigate one potential mechanism of the beneficial effect of thyroxine we studied renal tubular regeneration in this model of acute renal failure. Renal cortical uptake of labeled thymidine into DNA was significantly increased 48 h after the injection of potassium dichromate, and thyroxine administration further enhanced this repair process: 53.9 +/- 3.6 versus 81.4 +/- 5.3 dpm/200 pg of DNA (P = 0.0033).","The beneficial effects of thyroxine on nephrotoxic acute renal failure in the rat Abs: We were able to confirm previous studies demonstrating that administration of thyroxine is capable of ameliorating the severity of acute nephrotoxic renal failure in the rat. Nephrotoxic acute renal failure was induced by the subcutaneous injection of potassium dichromate (6.25 mg/kg) into Sprague-Dawley rats. Twenty-four hours after this injection, rats received an intraperitoneal injection of either thyroxine (80 micrograms/kg body wt) or normal saline. Forty-eight hours after the potassium dichromate injection, renal clearance studies were performed. Inulin clearance was significantly higher in the thyroxine-treated than in the saline-treated acute renal failure rats: 1.12 +/- 0.13 (SEM) mL/g versus 0.75 +/- 0.07 mL/min/g kidney wt (P = 0.025). Thyroxine treatment also effected an increase of p-aminohippuric acid extraction from 0.23 +/- 0.03 to 0.33 +/- 0.02 (P = 0.011) and a decrease in the fractional excretion of sodium from 0.38 +/- 0.21 to 0.11 +/- 0.03% (P = 0.037 by Mann-Whitney U test). In order to investigate one potential mechanism of the beneficial effect of thyroxine we studied renal tubular regeneration in this model of acute renal failure. Renal cortical uptake of labeled thymidine into DNA was significantly increased 48 h after the injection of potassium dichromate, and thyroxine administration further enhanced this repair process: 53.9 +/- 3.6 versus 81.4 +/- 5.3 dpm/200 pg of DNA (P = 0.0033)."
1234711,Wedeen and  Qian 1991,Chromium-induced kidney disease,"Kidney disease is often cited as one of the adverse effects of chromium, yet chronic renal disease due to occupational or environmental exposure to chromium has not yet been reported. Occasional cases of acute tubular necrosis (ATN) following massive absorption of chromate have been described. Chromate-induced ATN has been extensively studied in experimental animals following parenteral administration of large doses of potassium chromate (hexavalent) (15 mg/kg body weight). The chromate is selectively accumulated in the convoluted proximal tubule where necrosis occurs. An adverse long-term effect of low-dose chromium exposure on the kidneys is suggested by reports of low molecular weight (LMW) proteinuria in chromium workers. Excessive urinary excretion of beta 2-microglobulin, a specific proximal tubule brush border protein, and retinol-binding protein has been reported among chrome platers and welders. However, LMW proteinuria occurs after a variety of physiologic stresses, is usually reversible, and cannot by itself be considered evidence of chronic renal disease. Chromate-induced ATN and LMW proteinuria in chromium workers, nevertheless, raise the possibility that low-level, long-term exposure may produce persistent renal injury. The absence of evidence of chromate-induced exposure may produce persistent renal injury. The absence of evidence of chromate-induced chronic renal disease cannot be interpreted as evidence of the absence of such injury. Rather, it must be recognized that no prospective cohort or case-control study of the delayed renal effects of low-level, long-term exposure to chromium has been published.","Chromium-induced kidney disease Abs: Kidney disease is often cited as one of the adverse effects of chromium, yet chronic renal disease due to occupational or environmental exposure to chromium has not yet been reported. Occasional cases of acute tubular necrosis (ATN) following massive absorption of chromate have been described. Chromate-induced ATN has been extensively studied in experimental animals following parenteral administration of large doses of potassium chromate (hexavalent) (15 mg/kg body weight). The chromate is selectively accumulated in the convoluted proximal tubule where necrosis occurs. An adverse long-term effect of low-dose chromium exposure on the kidneys is suggested by reports of low molecular weight (LMW) proteinuria in chromium workers. Excessive urinary excretion of beta 2-microglobulin, a specific proximal tubule brush border protein, and retinol-binding protein has been reported among chrome platers and welders. However, LMW proteinuria occurs after a variety of physiologic stresses, is usually reversible, and cannot by itself be considered evidence of chronic renal disease. Chromate-induced ATN and LMW proteinuria in chromium workers, nevertheless, raise the possibility that low-level, long-term exposure may produce persistent renal injury. The absence of evidence of chromate-induced exposure may produce persistent renal injury. The absence of evidence of chromate-induced chronic renal disease cannot be interpreted as evidence of the absence of such injury. Rather, it must be recognized that no prospective cohort or case-control study of the delayed renal effects of low-level, long-term exposure to chromium has been published."
1234710,Dunn et al. 1991,Colonic complications after toxic tribal enemas,"Tribal enemas obtained from traditional healers are used widely in Southern Africa for a variety of indications. Inclusion of injurious substances such as potassium dichromate may cause serious colonic and renal complications. Nine such patients, in seven of whom chromate use was confirmed, presented after a mean delay of 7.3 days. All patients had bloody diarrhoea and vomiting and three underwent major colonic resection, requiring a total of ten procedures. One patient suffered mechanical perforation of the rectum, with subsequent necrotizing fasciitis, necessitating rectal excision. Eight patients had acute renal failure and seven required dialysis. One patient died. At follow-up one patient has chronic renal failure and only three are completely well. Although local medical practitioners are aware of the problem, the challenge of preventing harmful cultural practices remains.","Colonic complications after toxic tribal enemas Abs: Tribal enemas obtained from traditional healers are used widely in Southern Africa for a variety of indications. Inclusion of injurious substances such as potassium dichromate may cause serious colonic and renal complications. Nine such patients, in seven of whom chromate use was confirmed, presented after a mean delay of 7.3 days. All patients had bloody diarrhoea and vomiting and three underwent major colonic resection, requiring a total of ten procedures. One patient suffered mechanical perforation of the rectum, with subsequent necrotizing fasciitis, necessitating rectal excision. Eight patients had acute renal failure and seven required dialysis. One patient died. At follow-up one patient has chronic renal failure and only three are completely well. Although local medical practitioners are aware of the problem, the challenge of preventing harmful cultural practices remains."
1234708,Jamal et al. 1991,Distribution of chromium in the internal organs of potassium chromate treated chicks,"After exposure of growing chicks to different concentrations of dietary chromium (Cr) as potassium chromate (K2CrO4) for a period of 3 w, the Cr uptake by different internal organs was determined. More Cr was accumulated in the kidney, liver, pancreas and spleen than in the blood, muscle, heart and lung. A very small amount was found in the brains of the birds given different concentrations of Cr.","Distribution of chromium in the internal organs of potassium chromate treated chicks Abs: After exposure of growing chicks to different concentrations of dietary chromium (Cr) as potassium chromate (K2CrO4) for a period of 3 w, the Cr uptake by different internal organs was determined. More Cr was accumulated in the kidney, liver, pancreas and spleen than in the blood, muscle, heart and lung. A very small amount was found in the brains of the birds given different concentrations of Cr."
1234707,Odberg-Ferragut et al. 1991,"Stress protein synthesis, a potential toxicity marker in Escherichia coli","Various chemicals were tested in Escherichia coli for the ability to modify the cellular growth rate and to induce the synthesis of heat shock and stress proteins. The toxicity of chemicals as observed by modification of the growth rate depended on concentration and duration of treatment, except for thiram. In this last case, no modification was observed up to a concentration of 10 micrograms.ml-1. In contrast, all toxicants tested enhanced the synthesis of heat shock and stress proteins. The stress response was similar but not identical. Heat shock proteins and stress proteins appear to be a more sensitive toxicity marker than growth inhibition. Suggestions for the use of stress proteins as a practical bioassay are made.","Stress protein synthesis, a potential toxicity marker in Escherichia coli Abs: Various chemicals were tested in Escherichia coli for the ability to modify the cellular growth rate and to induce the synthesis of heat shock and stress proteins. The toxicity of chemicals as observed by modification of the growth rate depended on concentration and duration of treatment, except for thiram. In this last case, no modification was observed up to a concentration of 10 micrograms.ml-1. In contrast, all toxicants tested enhanced the synthesis of heat shock and stress proteins. The stress response was similar but not identical. Heat shock proteins and stress proteins appear to be a more sensitive toxicity marker than growth inhibition. Suggestions for the use of stress proteins as a practical bioassay are made."
1234706,Coogan et al. 1991,Differential DNA-protein crosslinking in lymphocytes and liver following chronic drinking water exposure of rats to potassium chromate,"Carcinogenic chromium (VI) compounds are persistent environmental contaminants with potential for human exposure through drinking water. One lesion associated with chromium (VI) exposure is the formation of DNA-protein crosslinks (DPC). In an attempt to develop markers of chromium exposure, the formation of DPC in lymphocytes was investigated. Fisher 344 rats were exposed to K2CrO4 in their drinking water for 3 and 6 weeks at concentrations of 100 and 200 ppm chromium. No DPC could be detected in isolated splenic lymphocytes using the alkaline elution technique or by using a polyclonal antibody to chromate-induced DPC. However, increased complexing of proteins with DNA was demonstrated in liver following 3 weeks of exposure at both 100 and 200 ppm chromium. Intraperitoneal administration of potassium chromate did not induce detectable DPC in lymphocytes; however, an increased association of proteins with isolated DNA was detected in the liver. DPC were also induced in isolated splenic lymphocytes following a 2-hr exposure in vitro to 100 microM K2CrO4 in a salts-glucose medium. Although chromium was detected in blood, liver, and kidney, blood levels were comparatively much lower. A comparison of chromium levels required to induce DPC in lymphocytes in vitro and the amount absorbed orally suggests that the white blood cell chromium levels following oral exposure may be too low to induce measurable DNA-protein crosslinks in lymphocytes.","Differential DNA-protein crosslinking in lymphocytes and liver following chronic drinking water exposure of rats to potassium chromate Abs: Carcinogenic chromium (VI) compounds are persistent environmental contaminants with potential for human exposure through drinking water. One lesion associated with chromium (VI) exposure is the formation of DNA-protein crosslinks (DPC). In an attempt to develop markers of chromium exposure, the formation of DPC in lymphocytes was investigated. Fisher 344 rats were exposed to K2CrO4 in their drinking water for 3 and 6 weeks at concentrations of 100 and 200 ppm chromium. No DPC could be detected in isolated splenic lymphocytes using the alkaline elution technique or by using a polyclonal antibody to chromate-induced DPC. However, increased complexing of proteins with DNA was demonstrated in liver following 3 weeks of exposure at both 100 and 200 ppm chromium. Intraperitoneal administration of potassium chromate did not induce detectable DPC in lymphocytes; however, an increased association of proteins with isolated DNA was detected in the liver. DPC were also induced in isolated splenic lymphocytes following a 2-hr exposure in vitro to 100 microM K2CrO4 in a salts-glucose medium. Although chromium was detected in blood, liver, and kidney, blood levels were comparatively much lower. A comparison of chromium levels required to induce DPC in lymphocytes in vitro and the amount absorbed orally suggests that the white blood cell chromium levels following oral exposure may be too low to induce measurable DNA-protein crosslinks in lymphocytes."
1234704,Bassi et al. 1991,Use of an established cell line in the evaluation of the cytotoxic effects of various chemicals,"The HTC hepatoma cell line was used as an &quot;in vitro&quot; model to detect the cytotoxicity of eighteen chemicals, chosen on the basis of different biological activities and physicochemical characteristics. Two different cytotoxicity assays measuring cell lethality (CS) or inhibition of cell growth (CF) were applicated to confluent cell monolayers or to colony-forming cells, respectively. Cells were exposed to the chemicals at doses ranging from 10(-6) M to 10(-2) M for 24 h. The results indicated a wide range of IC 50 (the concentration resulting in 50% inhibition of toxicity parameters) from as low as 1 microM (Potassium dichromate) to as high as 407.5 mM (Ethanol), the sensitivity of the CF test being greater than that of the CS test. A battery of cytotoxicity tests could be established in order to offer simple, rapid and economic methods which can be complementary and, in part, alternative to the use of laboratory animals.","Use of an established cell line in the evaluation of the cytotoxic effects of various chemicals Abs: The HTC hepatoma cell line was used as an &quot;in vitro&quot; model to detect the cytotoxicity of eighteen chemicals, chosen on the basis of different biological activities and physicochemical characteristics. Two different cytotoxicity assays measuring cell lethality (CS) or inhibition of cell growth (CF) were applicated to confluent cell monolayers or to colony-forming cells, respectively. Cells were exposed to the chemicals at doses ranging from 10(-6) M to 10(-2) M for 24 h. The results indicated a wide range of IC 50 (the concentration resulting in 50% inhibition of toxicity parameters) from as low as 1 microM (Potassium dichromate) to as high as 407.5 mM (Ethanol), the sensitivity of the CF test being greater than that of the CS test. A battery of cytotoxicity tests could be established in order to offer simple, rapid and economic methods which can be complementary and, in part, alternative to the use of laboratory animals."
1234703,Avnstorp 1991,Risk factors for cement eczema,"Risk factors for cement eczema were studied among workers employed in the Danish construction industry. 2 cohorts exposed to cement containing different concentrations of water-soluble chromate were examined. A statistically significant decrease in the number of workers with allergic cement eczema was found in the cohort exposed to cement with the lower water-soluble chromate concentration. Allergic cement eczema was found to have a greater extent of involvement than irritant cement eczema. A 3rd cohort was followed to evaluate individual risk factors. The degree of exposure to wet cement seems to have a certain, though not statistically significant, effect on the risk of developing irritant cement eczema. Individual preventive measures, such as the use of gloves and creams, did not seem to reduce the development of irritant cement eczema.","Risk factors for cement eczema Abs: Risk factors for cement eczema were studied among workers employed in the Danish construction industry. 2 cohorts exposed to cement containing different concentrations of water-soluble chromate were examined. A statistically significant decrease in the number of workers with allergic cement eczema was found in the cohort exposed to cement with the lower water-soluble chromate concentration. Allergic cement eczema was found to have a greater extent of involvement than irritant cement eczema. A 3rd cohort was followed to evaluate individual risk factors. The degree of exposure to wet cement seems to have a certain, though not statistically significant, effect on the risk of developing irritant cement eczema. Individual preventive measures, such as the use of gloves and creams, did not seem to reduce the development of irritant cement eczema."
1234702,Chen et al. 1991,Alteration in restriction enzyme digestion patterns detects DNA--protein complexes induced by chromate,"DNA--protein complexes isolated from CHO cells treated with at least 10-30 microM potassium chromate exhibited an alteration in the degradation of the DNA by restriction enzymes compared to DNA--protein complexes isolated from untreated cells. This alteration in restriction enzyme digestion of DNA--protein complexes induced by chromate was shown to depend upon the binding of trivalent chromium to the DNA and upon the protein associated with the DNA, since both EDTA pretreatment and protease K reversed the inhibition of restriction enzyme degradation of the DNA. The inhibition of restriction enzyme degradation of DNA--protein complexes may be utilized as an indirect way to detect DNA--protein complexing induced by chromate and perhaps other agents.","Alteration in restriction enzyme digestion patterns detects DNA--protein complexes induced by chromate Abs: DNA--protein complexes isolated from CHO cells treated with at least 10-30 microM potassium chromate exhibited an alteration in the degradation of the DNA by restriction enzymes compared to DNA--protein complexes isolated from untreated cells. This alteration in restriction enzyme digestion of DNA--protein complexes induced by chromate was shown to depend upon the binding of trivalent chromium to the DNA and upon the protein associated with the DNA, since both EDTA pretreatment and protease K reversed the inhibition of restriction enzyme degradation of the DNA. The inhibition of restriction enzyme degradation of DNA--protein complexes may be utilized as an indirect way to detect DNA--protein complexing induced by chromate and perhaps other agents."
1234697,Hojo and  Satomi 1991,In vivo nephrotoxicity induced in mice by chromium(VI): Involvement of glutathione and chromium(V),"The role of glutathione (GSH) and chromium (V) in chromium (VI)-induced nephrotoxicity in mice was investigated at 24 h after K2Cr(VI)2O7 ip injection. Nephrotoxicity was assessed by measurements of relative kidney weight and serum urea nitrogen. Cr(VI) nephrotoxicity was accompanied by decreased renal GSH and glutathione reductase (GSSG-R) levels. Pretreatment with buthionine sulfoximine, an inhibitor of GSH biosynthesis, enhanced Cr(VI)-induced nephrotoxicity, and remarkably diminished kidney GSH and GSSG-R levels. In contrast, pretreatment with glutathione methyl ester, a GSH-supplying agent, prevented Cr(VI) from exerting a harmful effect on mouse kidney and restored kidney GSH level. Administration of a Cr(V) compound, K3Cr(V)O8, induced much higher toxicity in mouse kidney than Cr(VI), but it failed to diminish renal GSH level. Another Cr(V) compound, Cr(V)-GSH complex, and Cr(III) nitrate did not cause a nephrotoxic effect in mice. The mechanism of Cr(VI)-induced nephrotoxicity was explained using GSH and Cr(V).","In vivo nephrotoxicity induced in mice by chromium(VI): Involvement of glutathione and chromium(V) Abs: The role of glutathione (GSH) and chromium (V) in chromium (VI)-induced nephrotoxicity in mice was investigated at 24 h after K2Cr(VI)2O7 ip injection. Nephrotoxicity was assessed by measurements of relative kidney weight and serum urea nitrogen. Cr(VI) nephrotoxicity was accompanied by decreased renal GSH and glutathione reductase (GSSG-R) levels. Pretreatment with buthionine sulfoximine, an inhibitor of GSH biosynthesis, enhanced Cr(VI)-induced nephrotoxicity, and remarkably diminished kidney GSH and GSSG-R levels. In contrast, pretreatment with glutathione methyl ester, a GSH-supplying agent, prevented Cr(VI) from exerting a harmful effect on mouse kidney and restored kidney GSH level. Administration of a Cr(V) compound, K3Cr(V)O8, induced much higher toxicity in mouse kidney than Cr(VI), but it failed to diminish renal GSH level. Another Cr(V) compound, Cr(V)-GSH complex, and Cr(III) nitrate did not cause a nephrotoxic effect in mice. The mechanism of Cr(VI)-induced nephrotoxicity was explained using GSH and Cr(V)."
1234696,Zhang et al. 1991,"Patch testing in cases of eczema and dermatitis in Beijing, China","Of 124 patients with eczema and dermatitis patch tested by the European standard series of allergens in the period from April to October 1989, 59 cases showed sensitivity to 1 or more allergens. Potassium dichromate, nickel sulphate and cobalt chloride were the 3 major sensitizers, with a frequency of 17.9%, 13.8% and 10.6%, respectively. The office and factory workers showed a higher incidence of positive reactions than the student group. The environment of the office and the factory seems to be the potential source of exacerbating factors of eczematous skin disease.","Patch testing in cases of eczema and dermatitis in Beijing, China Abs: Of 124 patients with eczema and dermatitis patch tested by the European standard series of allergens in the period from April to October 1989, 59 cases showed sensitivity to 1 or more allergens. Potassium dichromate, nickel sulphate and cobalt chloride were the 3 major sensitizers, with a frequency of 17.9%, 13.8% and 10.6%, respectively. The office and factory workers showed a higher incidence of positive reactions than the student group. The environment of the office and the factory seems to be the potential source of exacerbating factors of eczematous skin disease."
1234693,Nethercott and  Holness 1991,Dermatologic problems of musicians,,Dermatologic problems of musicians Abs: 
1234691,De Ceaurriz and  Ban 1991,Effects of probenecid and acivicin on potassium dichromate-induced acute nephrotoxicity in mice,"Male OF1 mice were injected subcutaneously with 80 mg/kg potassium dichromate (K2Cr2O7). Examination of cryostat kidney sections stained for alkaline phosphatase (APP) revealed damage to about 40-70% of the proximal tubules after 8 h. Pretreatment with the organic anionic transport inhibitor probenecid (i.p., 3 x 0.75 mmol/kg) reduced the number of damaged tubules by 60% in mice treated with potassium dichromate. Pretreatment with the gamma-glutamyltranspeptidase (gamma-GT) inactivator acivicin (AT-125, 50 mg/kg p.o., plus 50 mg/kg i.p.) failed to prevent chromate-induced renal toxicity. These results support the conclusion that a probenecid-sensitive transport process, but not a gamma-GT-catalyzed degradation, is involved in the mouse renal toxicity of potassium dichromate.","Effects of probenecid and acivicin on potassium dichromate-induced acute nephrotoxicity in mice Abs: Male OF1 mice were injected subcutaneously with 80 mg/kg potassium dichromate (K2Cr2O7). Examination of cryostat kidney sections stained for alkaline phosphatase (APP) revealed damage to about 40-70% of the proximal tubules after 8 h. Pretreatment with the organic anionic transport inhibitor probenecid (i.p., 3 x 0.75 mmol/kg) reduced the number of damaged tubules by 60% in mice treated with potassium dichromate. Pretreatment with the gamma-glutamyltranspeptidase (gamma-GT) inactivator acivicin (AT-125, 50 mg/kg p.o., plus 50 mg/kg i.p.) failed to prevent chromate-induced renal toxicity. These results support the conclusion that a probenecid-sensitive transport process, but not a gamma-GT-catalyzed degradation, is involved in the mouse renal toxicity of potassium dichromate."
1234690,Hayaran et al. 1992,Cytoarchitectural development of the human dentate nucleus: a Golgi study,"Golgi-stained sections of the human cerebellar dentate nucleus (DN) at various gestational ages were examined to study the dendritic proliferation and maturation of the DN neurons. Bipolar cells were seen at 14-15 weeks. By 19-20 weeks, three cell types were identifiable: bipolar, hemispheric and pyriform. The cells of the dorsomedial region matured earlier than those of the ventrolateral region. In addition to the above cell types, multipolar and nuclear boundary cells were observable at 24-25 weeks. The five cell types persisted during subsequent development. At no stage of development was any neuronal organizational pattern apparent. A remarkable dendritic proliferation occurred at 27-28 weeks. Spines and filiform processes were seen at 34 weeks of intrauterine life.","Cytoarchitectural development of the human dentate nucleus: a Golgi study Abs: Golgi-stained sections of the human cerebellar dentate nucleus (DN) at various gestational ages were examined to study the dendritic proliferation and maturation of the DN neurons. Bipolar cells were seen at 14-15 weeks. By 19-20 weeks, three cell types were identifiable: bipolar, hemispheric and pyriform. The cells of the dorsomedial region matured earlier than those of the ventrolateral region. In addition to the above cell types, multipolar and nuclear boundary cells were observable at 24-25 weeks. The five cell types persisted during subsequent development. At no stage of development was any neuronal organizational pattern apparent. A remarkable dendritic proliferation occurred at 27-28 weeks. Spines and filiform processes were seen at 34 weeks of intrauterine life."
1234689,Xu et al. 1992,Brain aluminum in Alzheimer's disease using an improved GFAAS method,"Aluminum (Al) has been determined in autopsy brain samples (20 mg, dry weight) from 10 histologically verified Alzheimer's disease (AD) patients and 10 neurologically normal controls using an improved graphite furnace atomic absorption method. The method makes use of a potassium dichromate matrix modifier to circumvent interferences to the Al determination by the high levels of phosphorus and alkali metals in brain tissue. Brain regions studied included middle frontal gyrus, hippocampus, inferior parietal lobule, and the superior and middle temporal gyri. Small, but significant (p &lt; 0.05) elevations of Al were observed in AD hippocampus, inferior parietal lobule and superior and middle temporal gyri, compared to corresponding control tissues. In contrast to other reports in the literature, no extremely high Al levels (&gt; 20 micrograms/g, dry weight) were observed in our samples. Our highest value for Al in AD brain was 8.0 micrograms/g. These results suggest that there is a small focal increase of Al in specific regions of AD brain compared to age-matched controls. The fact that the increase is small, coupled with the analytical difficulties of accurate bulk sample Al determinations by any technique in the brain matrix, may account for the discordant literature reports for Al in AD brain.","Brain aluminum in Alzheimer's disease using an improved GFAAS method Abs: Aluminum (Al) has been determined in autopsy brain samples (20 mg, dry weight) from 10 histologically verified Alzheimer's disease (AD) patients and 10 neurologically normal controls using an improved graphite furnace atomic absorption method. The method makes use of a potassium dichromate matrix modifier to circumvent interferences to the Al determination by the high levels of phosphorus and alkali metals in brain tissue. Brain regions studied included middle frontal gyrus, hippocampus, inferior parietal lobule, and the superior and middle temporal gyri. Small, but significant (p &lt; 0.05) elevations of Al were observed in AD hippocampus, inferior parietal lobule and superior and middle temporal gyri, compared to corresponding control tissues. In contrast to other reports in the literature, no extremely high Al levels (&gt; 20 micrograms/g, dry weight) were observed in our samples. Our highest value for Al in AD brain was 8.0 micrograms/g. These results suggest that there is a small focal increase of Al in specific regions of AD brain compared to age-matched controls. The fact that the increase is small, coupled with the analytical difficulties of accurate bulk sample Al determinations by any technique in the brain matrix, may account for the discordant literature reports for Al in AD brain."
1234685,Bruckner-Tuderman et al. 1992,Patch test results of the Dermatology Clinic Zurich in 1989: personal computer-aided statistical evaluation,"The patch test results of 921 consecutively tested patients were registered on an IBM personal computer. A computer program based on the dBase III plus database software, especially designed for this purpose, was used. The statistical evaluation was performed with dBase III plus. 59% of the probands were females and 41% males. The average age was 42.8 years. 26% of the probands were inpatients and 74% outpatients. A majority of the patients presented with eczema of the hands, face or the lower legs. The largest occupational groups were houseworkers and cleaning personnel, office workers and pensioners. To 450 of the 921 patients, at least 4 test series were applied simultaneously. These included European standard, vehicles and emulgators, topical medications, and preservatives and biocides. The other 20 test series available were employed only by 2-81 patients each. The highest sensitization rates were found with: nickel, 18.7%; cobalt, 10.2%; balsam of Peru, 8.8%; framycetin, 8.0%; neomycin, 6.8%; potassium dichromate, 6.1%; p-phenylene diamine, 5.4%; paramix, 4.9%; formaldehyde, 4.8%, and (chlor)methylisothiazolinone, 4.7%. The critical evaluation of the data showed two kinds of problems: first, test-specific aspects led to optimization of the patch test procedures; second, the crucial importance of an adequate statistical analysis for epidemiological investigation was revealed.","Patch test results of the Dermatology Clinic Zurich in 1989: personal computer-aided statistical evaluation Abs: The patch test results of 921 consecutively tested patients were registered on an IBM personal computer. A computer program based on the dBase III plus database software, especially designed for this purpose, was used. The statistical evaluation was performed with dBase III plus. 59% of the probands were females and 41% males. The average age was 42.8 years. 26% of the probands were inpatients and 74% outpatients. A majority of the patients presented with eczema of the hands, face or the lower legs. The largest occupational groups were houseworkers and cleaning personnel, office workers and pensioners. To 450 of the 921 patients, at least 4 test series were applied simultaneously. These included European standard, vehicles and emulgators, topical medications, and preservatives and biocides. The other 20 test series available were employed only by 2-81 patients each. The highest sensitization rates were found with: nickel, 18.7%; cobalt, 10.2%; balsam of Peru, 8.8%; framycetin, 8.0%; neomycin, 6.8%; potassium dichromate, 6.1%; p-phenylene diamine, 5.4%; paramix, 4.9%; formaldehyde, 4.8%, and (chlor)methylisothiazolinone, 4.7%. The critical evaluation of the data showed two kinds of problems: first, test-specific aspects led to optimization of the patch test procedures; second, the crucial importance of an adequate statistical analysis for epidemiological investigation was revealed."
1234683,Gajewska et al. 1992,Spectrofluorimetric assay of azathioprine and 6-mercaptopurine in human blood plasma,"In this review is discussed a new modified assay measuring Azathioprine (AZA) and 6-Mercaptopurine (6-MP) in human plasma using spectrofluorimetric method. After completed hydrolysis of AZA to 6-MP, the last has been oxidised to Purine-6-sulphonate by two methods: using potassium chromate in the first method and potassium permanganate in the second one. Fluorescence of the solutions was measured at 393 nm with an excitation wavelength of 289 nm. Percentage of 6-MP remaining in toluene in the first method was 58 to 64. Comparing both methods of determination 6-MP it was noticed, that the first method is repeatable and can be applied for therapeutic drug monitoring.","Spectrofluorimetric assay of azathioprine and 6-mercaptopurine in human blood plasma Abs: In this review is discussed a new modified assay measuring Azathioprine (AZA) and 6-Mercaptopurine (6-MP) in human plasma using spectrofluorimetric method. After completed hydrolysis of AZA to 6-MP, the last has been oxidised to Purine-6-sulphonate by two methods: using potassium chromate in the first method and potassium permanganate in the second one. Fluorescence of the solutions was measured at 393 nm with an excitation wavelength of 289 nm. Percentage of 6-MP remaining in toluene in the first method was 58 to 64. Comparing both methods of determination 6-MP it was noticed, that the first method is repeatable and can be applied for therapeutic drug monitoring."
1234682,Gey van Pittius et al. 1992,Effects of chromium during pH change on blood coagulation in Tilapia sparrmanii (Cichlidae),"1. Tilapia sparrmanii was exposed to 0.098 mg/l potassium dichromate. 2. The effect of chromium on blood coagulation was measured with a thrombelastograph at a pH of 5, 7.4 and 9 over 96 hr, as well as an uncontrolled pH after 2 weeks of exposure. 3. The prolonged kinetic times and reduced maximal amplitudes at a pH of 7, 4 and 9, differed significantly from the control values. 4. Thrombelastograms reflected a decrease in the clotting ability of fish blood, with an increase in pH, which is typical of thrombocytopenia. 5. It was evident that the exposure of fish to chromium led to clotting defects that caused internal bleeding.","Effects of chromium during pH change on blood coagulation in Tilapia sparrmanii (Cichlidae) Abs: 1. Tilapia sparrmanii was exposed to 0.098 mg/l potassium dichromate. 2. The effect of chromium on blood coagulation was measured with a thrombelastograph at a pH of 5, 7.4 and 9 over 96 hr, as well as an uncontrolled pH after 2 weeks of exposure. 3. The prolonged kinetic times and reduced maximal amplitudes at a pH of 7, 4 and 9, differed significantly from the control values. 4. Thrombelastograms reflected a decrease in the clotting ability of fish blood, with an increase in pH, which is typical of thrombocytopenia. 5. It was evident that the exposure of fish to chromium led to clotting defects that caused internal bleeding."
1234681,Awogi et al. 1992,Induction of micronucleated reticulocytes by potassium bromate and potassium chromate in CD-1 male mice,Micronucleus tests of potassium bromate (KBrO3) and potassium chromate (K2CrO4) were conducted with peripheral blood reticulocytes (PB-RETs) of CD-1 male mice dose intraperitoneally. Peripheral blood cells collected from the tail were stained supravitally with acridine orange (AO) using AO-coated glass slides. Both KBrO3 and K2CrO4 induced micronuclei in PB-RETs in the same manner as in polychromatic erythrocytes of bone marrow.,Induction of micronucleated reticulocytes by potassium bromate and potassium chromate in CD-1 male mice Abs: Micronucleus tests of potassium bromate (KBrO3) and potassium chromate (K2CrO4) were conducted with peripheral blood reticulocytes (PB-RETs) of CD-1 male mice dose intraperitoneally. Peripheral blood cells collected from the tail were stained supravitally with acridine orange (AO) using AO-coated glass slides. Both KBrO3 and K2CrO4 induced micronuclei in PB-RETs in the same manner as in polychromatic erythrocytes of bone marrow.
1234679,Gonçalo et al. 1992,Allergic contact dermatitis in children. A multicenter study of the Portuguese Contact Dermatitis Group (GPEDC),"The authors report a study of allergic contact dermatitis in 329 Portuguese children of 14 years or younger. 170 children (64 male and 106 female) reacted to 1 or more allergens. Most of these were in the 11-14 years group. The main allergens were nickel, thimerosal, cobalt, mercury, fragrance-mix and potassium dichromate. Nickel reactivity predominated in females over the whole group, but a greater number of males younger than 5 years reacted to nickel. The number of positive reactions increased with age, but this was not accompained by an increase in the % of relevant tests. 12 children, all of them 13 or 14 years-old, had an occupational allergic contact dermatitis.","Allergic contact dermatitis in children. A multicenter study of the Portuguese Contact Dermatitis Group (GPEDC) Abs: The authors report a study of allergic contact dermatitis in 329 Portuguese children of 14 years or younger. 170 children (64 male and 106 female) reacted to 1 or more allergens. Most of these were in the 11-14 years group. The main allergens were nickel, thimerosal, cobalt, mercury, fragrance-mix and potassium dichromate. Nickel reactivity predominated in females over the whole group, but a greater number of males younger than 5 years reacted to nickel. The number of positive reactions increased with age, but this was not accompained by an increase in the % of relevant tests. 12 children, all of them 13 or 14 years-old, had an occupational allergic contact dermatitis."
1234676,Sakai and  Uchida 1992,Comparative effects of potassium dichromate on the mutagenicity of some nitrohydrocarbons and methylating agents,BIOSIS COPYRIGHT: BIOL ABS. RRM BACTERIA MICROORGANISM ENVIRONMENTAL TOXICITY OCCUPATIONAL HEALTH AND SAFETY MUTAGEN CARCINOGEN METALS TOXICITY,Comparative effects of potassium dichromate on the mutagenicity of some nitrohydrocarbons and methylating agents Abs: BIOSIS COPYRIGHT: BIOL ABS. RRM BACTERIA MICROORGANISM ENVIRONMENTAL TOXICITY OCCUPATIONAL HEALTH AND SAFETY MUTAGEN CARCINOGEN METALS TOXICITY
1234675,Susa et al. 1992,Protective effects of thiol compounds on chromate-induced cytotoxicity in HeLa cells,"The effects of several thiol compounds on the cytotoxicity induced by chromate (potassium dichromate) were examined. HeLa cells were incubated in Eagle's minimum essential medium (MEM) with or without the chromate alone, or with both chromate and any one of L-cysteine ethyl ester (LCysEE), L-cystcine methyl ester (LCysME), N-acetyl-L-(+)-cysteine, 2, 3-dimercaptosuccinic acid (DMSA), 2, 3-dimercapto-1-propanesulfonic acid (DMPS), or dithiothreitol. After a given period of incubation, the number of viable cells was counted using thc trypan blue exclusion test and the chromium content of the cells was cstimated by atomic absorption spectrophotometry. The results obtained were as follows. 1)Chromate-induced cytotoxicity evaluated by inhibition of cell growth at 3 days of incubation was diminished by all of the thiol compounds tested when thc cel1s were incubated in MEM with 2.5 to 10.0?M chromate and 25 to 100?M thiol compounds. 2)All of the thiol compounds produced a concentration-dependent reduction of chromate when a solution of the thiol compound (12.5 to 100?M) was mixed with a solution of chromate (10?M) in distilled water. 3)When cells werc incubated in MEM with both 10?M chromate and 25 to 100?M thiol compounds, the chromium content of the cells at 6 hr of incubation was decreascd in a concentration-dependent manner. 4)When these thiol compounds were added to MEM 1 hr before or after chromate, no or little protective effccts of these thiol compounds against chromate-induced cytotoxicity and chromium uptake by the cel1s were observed. The results of this study demonstrate that the thiol compounds, especially LCysEE, LCysME, DMSA, and DMPS are useful for treating chromate-induced cytotoxicity when they are given immediately after intakc of the metal and suggest that a part of this effect may be due to decrease in chromium uptake by the cells accompanying the reduction of chromate.","Protective effects of thiol compounds on chromate-induced cytotoxicity in HeLa cells Abs: The effects of several thiol compounds on the cytotoxicity induced by chromate (potassium dichromate) were examined. HeLa cells were incubated in Eagle's minimum essential medium (MEM) with or without the chromate alone, or with both chromate and any one of L-cysteine ethyl ester (LCysEE), L-cystcine methyl ester (LCysME), N-acetyl-L-(+)-cysteine, 2, 3-dimercaptosuccinic acid (DMSA), 2, 3-dimercapto-1-propanesulfonic acid (DMPS), or dithiothreitol. After a given period of incubation, the number of viable cells was counted using thc trypan blue exclusion test and the chromium content of the cells was cstimated by atomic absorption spectrophotometry. The results obtained were as follows. 1)Chromate-induced cytotoxicity evaluated by inhibition of cell growth at 3 days of incubation was diminished by all of the thiol compounds tested when thc cel1s were incubated in MEM with 2.5 to 10.0?M chromate and 25 to 100?M thiol compounds. 2)All of the thiol compounds produced a concentration-dependent reduction of chromate when a solution of the thiol compound (12.5 to 100?M) was mixed with a solution of chromate (10?M) in distilled water. 3)When cells werc incubated in MEM with both 10?M chromate and 25 to 100?M thiol compounds, the chromium content of the cells at 6 hr of incubation was decreascd in a concentration-dependent manner. 4)When these thiol compounds were added to MEM 1 hr before or after chromate, no or little protective effccts of these thiol compounds against chromate-induced cytotoxicity and chromium uptake by the cel1s were observed. The results of this study demonstrate that the thiol compounds, especially LCysEE, LCysME, DMSA, and DMPS are useful for treating chromate-induced cytotoxicity when they are given immediately after intakc of the metal and suggest that a part of this effect may be due to decrease in chromium uptake by the cells accompanying the reduction of chromate."
1234674,Lim et al. 1992,Changing trends in the epidemiology of contact dermatitis in Singapore,"All patients seen in the Contact Dermatitis Clinic of the National Skin Centre, Singapore (and the former Middle Road Hospital) between January 1986 and December 1990 were analysed retrospectively. 5557 patients comprising 2634 (47.4%) males and 2923 (52.6%) females were patch tested. 3154 (56.8%) patients had 1 or more positive reactions. The majority of the patients were Chinese (78.0%), followed by Malays (11.5%), Indians (8.1%) and other minority races (2.4%). The majority of positive reactions belonged to the 21-40 age group. The incidence of positivity decreased after 60 years. The commonest allergens responsible were nickel (17.7%), fragrance (13.3%), neomycin (6.9%), colophony (6.6%) and proflavine (6.5%). Both neomycin and proflavine were commonly used as over-the-counter medicaments. Compared to an earlier report in 1988, there were differences in the incidence of contact sensitivity to some allergens. Potassium dichromate, which used to be a common allergen, was less common. Some allergens (carba-mix, naphthyl-mix, caine-mix and PCMX) have been removed from our standard series as they were uncommon causes of contact allergy. Thimerosal and Amerchol L-101 were added in their place.","Changing trends in the epidemiology of contact dermatitis in Singapore Abs: All patients seen in the Contact Dermatitis Clinic of the National Skin Centre, Singapore (and the former Middle Road Hospital) between January 1986 and December 1990 were analysed retrospectively. 5557 patients comprising 2634 (47.4%) males and 2923 (52.6%) females were patch tested. 3154 (56.8%) patients had 1 or more positive reactions. The majority of the patients were Chinese (78.0%), followed by Malays (11.5%), Indians (8.1%) and other minority races (2.4%). The majority of positive reactions belonged to the 21-40 age group. The incidence of positivity decreased after 60 years. The commonest allergens responsible were nickel (17.7%), fragrance (13.3%), neomycin (6.9%), colophony (6.6%) and proflavine (6.5%). Both neomycin and proflavine were commonly used as over-the-counter medicaments. Compared to an earlier report in 1988, there were differences in the incidence of contact sensitivity to some allergens. Potassium dichromate, which used to be a common allergen, was less common. Some allergens (carba-mix, naphthyl-mix, caine-mix and PCMX) have been removed from our standard series as they were uncommon causes of contact allergy. Thimerosal and Amerchol L-101 were added in their place."
1234672,CDC 1992,"Lead chromate exposures and elevated blood lead levels in workers in the plastics pigmenting industry--Texas, 1990","In June 1990, the Dallas (Texas) County Health Department received a physician's report of an elevated blood lead level (BLL) (52 micrograms/dL) for an employee of a company that formulates color concentrates for the plastics industry. The physician had been evaluating the employee for severe headaches of uncertain etiology; however, he requested a BLL analysis when the employee's occupational history suggested possible lead exposure.","Lead chromate exposures and elevated blood lead levels in workers in the plastics pigmenting industry--Texas, 1990 Abs: In June 1990, the Dallas (Texas) County Health Department received a physician's report of an elevated blood lead level (BLL) (52 micrograms/dL) for an employee of a company that formulates color concentrates for the plastics industry. The physician had been evaluating the employee for severe headaches of uncertain etiology; however, he requested a BLL analysis when the employee's occupational history suggested possible lead exposure."
1234670,Sengupta et al. 1992,Impact of chromium on lipoperoxidative processes and subsequent operation of the glutathione cycle in rat renal system,"Oral administration of K2Cr2O7 to male albino rats at an acute dose of 1500 mg/kg body wt/day for 3 days brought about sharp decrease in the activities of glucose-6-phosphate dehydrogenase and glutathione reductase of kidney epithelial cells. The scavenging system of kidney epithelium is also affected as evident by the highly significant fall in the activities of glutathione peroxidase, superoxide dismutase and catalase which ultimately leads to the increase in lipid peroxidation value in kidney cortical homogenate. However, glutathione-s-transferase activity in cytosol and glutathione and total thiol content in cortical homogenate were not altered. Chronic oral administration of K2Cr2O7 (300 mg/kg body wt/day) for 30 days to rats lead to elevation in the activities of glutathione peroxidase, glutathione reductase, glutathione-s-transferase, superoxide dismutase and catalase with no change in glucose-6-phosphate dehydrogenase activity in epithelial cells. This might lead to the increase in glutathione and total thiol status and decrease in lipid peroxidation value in whole homogenate system.","Impact of chromium on lipoperoxidative processes and subsequent operation of the glutathione cycle in rat renal system Abs: Oral administration of K2Cr2O7 to male albino rats at an acute dose of 1500 mg/kg body wt/day for 3 days brought about sharp decrease in the activities of glucose-6-phosphate dehydrogenase and glutathione reductase of kidney epithelial cells. The scavenging system of kidney epithelium is also affected as evident by the highly significant fall in the activities of glutathione peroxidase, superoxide dismutase and catalase which ultimately leads to the increase in lipid peroxidation value in kidney cortical homogenate. However, glutathione-s-transferase activity in cytosol and glutathione and total thiol content in cortical homogenate were not altered. Chronic oral administration of K2Cr2O7 (300 mg/kg body wt/day) for 30 days to rats lead to elevation in the activities of glutathione peroxidase, glutathione reductase, glutathione-s-transferase, superoxide dismutase and catalase with no change in glucose-6-phosphate dehydrogenase activity in epithelial cells. This might lead to the increase in glutathione and total thiol status and decrease in lipid peroxidation value in whole homogenate system."
1234669,Elliott and  Patchin 1992,Aminoglycoside-mediated calciuresis,"Gentamicin and calcium compete for binding to various tissues including renal tubular brush border. Moreover, gentamicin has calcium channel blocking properties in cardiac and vascular tissue. Calcium channel blockade in vitro by nifedipine or verapamil decreases calcium uptake by renal tubular epithelial cells. To determine the acute in vivo effects of gentamicin on renal calcium handling, we administered gentamicin 10 mg/kg as an i.v. bolus to F344 rats. Within 30 min of administration fractional excretion of calcium increased from a mean of 11 +/- 2% (S.E.M.) to 128 +/- 37%. There was no change in glomerular filtration rate, or urinary sodium, potassium or phosphate excretion. Maximum calciuria occurred immediately after administration, was dose-related and was correlated to preadministration urinary calcium. Urine calcium concentration was also correlated to urinary gentamicin concentration. Urinary calcium returned to base-line values within 90 min of bolus gentamicin administration, but remained elevated if a gentamicin infusion was continued. Parathyroidectomy and dietary calcium content did not affect gentamicin calciuria. Tobramycin, a less nephrotoxic aminoglycoside in the F344 rat, had calciuric effects similar to gentamicin. Verapamil, a calcium channel blocker which is largely excluded from the urine, and potassium dichromate, a nonaminoglycoside proximal tubular nephrotoxin, had no effect on urinary calcium. The mechanism of aminoglycoside calciuria is unclear, but may be related to competition between aminoglycosides and calcium for brush border binding, intraluminal calcium channel blockade by aminoglycosides or aminoglycoside inhibition of basolateral calcium ATPase or Na-K ATPase.","Aminoglycoside-mediated calciuresis Abs: Gentamicin and calcium compete for binding to various tissues including renal tubular brush border. Moreover, gentamicin has calcium channel blocking properties in cardiac and vascular tissue. Calcium channel blockade in vitro by nifedipine or verapamil decreases calcium uptake by renal tubular epithelial cells. To determine the acute in vivo effects of gentamicin on renal calcium handling, we administered gentamicin 10 mg/kg as an i.v. bolus to F344 rats. Within 30 min of administration fractional excretion of calcium increased from a mean of 11 +/- 2% (S.E.M.) to 128 +/- 37%. There was no change in glomerular filtration rate, or urinary sodium, potassium or phosphate excretion. Maximum calciuria occurred immediately after administration, was dose-related and was correlated to preadministration urinary calcium. Urine calcium concentration was also correlated to urinary gentamicin concentration. Urinary calcium returned to base-line values within 90 min of bolus gentamicin administration, but remained elevated if a gentamicin infusion was continued. Parathyroidectomy and dietary calcium content did not affect gentamicin calciuria. Tobramycin, a less nephrotoxic aminoglycoside in the F344 rat, had calciuric effects similar to gentamicin. Verapamil, a calcium channel blocker which is largely excluded from the urine, and potassium dichromate, a nonaminoglycoside proximal tubular nephrotoxin, had no effect on urinary calcium. The mechanism of aminoglycoside calciuria is unclear, but may be related to competition between aminoglycosides and calcium for brush border binding, intraluminal calcium channel blockade by aminoglycosides or aminoglycoside inhibition of basolateral calcium ATPase or Na-K ATPase."
1234668,Hayashi et al. 1992,Flow cytometric micronucleus test with mouse peripheral erythrocytes,"Flow cytometric (FC) analysis was applied to micronucleus test with mouse peripheral blood erythrocytes. The method is based on the measurement of peak fluorescence (PFL) of sphered glutaraldehyde-fixed erythrocytes before and after staining with 4',6-diamidino-2-phenylindole (DAPI), in an EPICS V flow cytometer. The frequency of micronucleated erythrocytes (MNEs) is calculated by a computer program comparing PFL data obtained with and without DAPI. To evaluate the method, male ddY mice were treated with 6-mercaptopurine and benzene and blood was collected from tail vein at intervals of 4-7 days. Both microscopic and FC analysis showed a steady increase in the incidence of MNEs, reaching a plateau when about a month had passed from the start of the treatments. The effects of benzo[a]pyrene, mitomycin C,N-ethyl-N-nitrosourea, bromodichloromethane and potassium chromate (VI) were also studied with both the manual and FC assay in samples collected a week after five weekly treatments. The percentages of MNEs obtained manually and by the FC measurements showed good correlation, the former three chemicals being positive and the latter two negative or, in the FC analysis, difficult to classify. Because of the high number of cells examined (50,000/animal), the FC analysis was probably more sensitive than the manual method where only 2000 cells were scored per animal. This was further suggested by (i) steady time responses, also for individual animals, in the FC results on 6-mercaptopurine and benzene, (ii) overall reduced inter-individual variation in the FC measurements, and (iii) detection of MNE induction by mitomycin C at a lower dose level with the FC than the manual analysis.(ABSTRACT TRUNCATED AT 250 WORDS)","Flow cytometric micronucleus test with mouse peripheral erythrocytes Abs: Flow cytometric (FC) analysis was applied to micronucleus test with mouse peripheral blood erythrocytes. The method is based on the measurement of peak fluorescence (PFL) of sphered glutaraldehyde-fixed erythrocytes before and after staining with 4',6-diamidino-2-phenylindole (DAPI), in an EPICS V flow cytometer. The frequency of micronucleated erythrocytes (MNEs) is calculated by a computer program comparing PFL data obtained with and without DAPI. To evaluate the method, male ddY mice were treated with 6-mercaptopurine and benzene and blood was collected from tail vein at intervals of 4-7 days. Both microscopic and FC analysis showed a steady increase in the incidence of MNEs, reaching a plateau when about a month had passed from the start of the treatments. The effects of benzo[a]pyrene, mitomycin C,N-ethyl-N-nitrosourea, bromodichloromethane and potassium chromate (VI) were also studied with both the manual and FC assay in samples collected a week after five weekly treatments. The percentages of MNEs obtained manually and by the FC measurements showed good correlation, the former three chemicals being positive and the latter two negative or, in the FC analysis, difficult to classify. Because of the high number of cells examined (50,000/animal), the FC analysis was probably more sensitive than the manual method where only 2000 cells were scored per animal. This was further suggested by (i) steady time responses, also for individual animals, in the FC results on 6-mercaptopurine and benzene, (ii) overall reduced inter-individual variation in the FC measurements, and (iii) detection of MNE induction by mitomycin C at a lower dose level with the FC than the manual analysis.(ABSTRACT TRUNCATED AT 250 WORDS)"
1234666,Ferro et al. 1992,Comparative assessment of the cytotoxic effects of different xenobiotics in three hepatoma cell lines,"MH1C1, HTC and HEPA 1c1c7 hepatoma cell lines were selected in this study as the bioindicators of the cytotoxicity induced by six chemicals: butylated hydroxyanisole (BHA), butylated hydroxytoluene (BHT), cycloheximide (CHE), cyclophosphamide (CPA), potassium dichromate (Cr VI) and 2,4-dinitrophenol (DNP). The concentrations used were in the range from 10(-6) mol/l to 10(-2) mol/l, and the exposure time was 24 h. Two end-points were measured to evaluate cytotoxicity: the detachment of dead cells from the monolayer (CS), as evaluated by detection of the total macromolecules present in the cell monolayers solubilized in alkali and the loss of colony-forming efficiency (CF). The dose-response curves were different from one compound to another, but generally similar with the two assays, the colony formation being the most sensitive test. Some technical problems like the toxicity of the solvents at the highest concentrations, the different sizes of colonies, the unspecific cellular detachment due to overgrowth during the experimental time, can be overcome by accurate standardization of the protocols used for each cell line. The sensitivity of the three cell lines was very similar, with some differences in the case of compounds exerting intermediate toxic effects, like CHE and DNP. The most toxic compound was Cr (VI), the least toxic one was CPA. The low cytotoxic effects displayed by CPA could be due to a lack of bioactivation and/or an increase of the inactivating enzymes, which are typical of hepatoma cell lines.","Comparative assessment of the cytotoxic effects of different xenobiotics in three hepatoma cell lines Abs: MH1C1, HTC and HEPA 1c1c7 hepatoma cell lines were selected in this study as the bioindicators of the cytotoxicity induced by six chemicals: butylated hydroxyanisole (BHA), butylated hydroxytoluene (BHT), cycloheximide (CHE), cyclophosphamide (CPA), potassium dichromate (Cr VI) and 2,4-dinitrophenol (DNP). The concentrations used were in the range from 10(-6) mol/l to 10(-2) mol/l, and the exposure time was 24 h. Two end-points were measured to evaluate cytotoxicity: the detachment of dead cells from the monolayer (CS), as evaluated by detection of the total macromolecules present in the cell monolayers solubilized in alkali and the loss of colony-forming efficiency (CF). The dose-response curves were different from one compound to another, but generally similar with the two assays, the colony formation being the most sensitive test. Some technical problems like the toxicity of the solvents at the highest concentrations, the different sizes of colonies, the unspecific cellular detachment due to overgrowth during the experimental time, can be overcome by accurate standardization of the protocols used for each cell line. The sensitivity of the three cell lines was very similar, with some differences in the case of compounds exerting intermediate toxic effects, like CHE and DNP. The most toxic compound was Cr (VI), the least toxic one was CPA. The low cytotoxic effects displayed by CPA could be due to a lack of bioactivation and/or an increase of the inactivating enzymes, which are typical of hepatoma cell lines."
1234664,Arikan and  Kulak 1992,"A study of chromium, nickel and cobalt hypersensitivity","Hypersensitivity reactions to chromium, nickel and cobalt were investigated in the preclinical, fourth year and fifth year students of the Dentistry Faculty of Marmara University, Türkiye. A Standard patch test was performed. Four patches were applied to the shoulder blades of the students. Three of them contained small amounts of 0.5% potassium chromate, 5% nickel sulphate and 1% cobalt chloride respectively. The fourth (control) patch was of petroleum jelly. Questionnaires were used to determine sex and history of any previous allergy to jewelry. After 48 hours, the patches were removed and results assessed. For each base metal, no statistically significant difference was found in the incidence of hypersensitivity reaction between the groups. Nor was there a significant difference in response found between metals, for all of the students tested. Although women were found to have a higher rate of nickel hypersensitivity than men, no such sex difference was found chromium and cobalt. No significant relationship was found between a history of allergy to jewelry and chromium hypersensitivity, however there was a significant difference for nickel and cobalt hypersensitivity. In confirmation of our tests, significant relationships were found between previous allergy histories and the respective patch test results.","A study of chromium, nickel and cobalt hypersensitivity Abs: Hypersensitivity reactions to chromium, nickel and cobalt were investigated in the preclinical, fourth year and fifth year students of the Dentistry Faculty of Marmara University, Türkiye. A Standard patch test was performed. Four patches were applied to the shoulder blades of the students. Three of them contained small amounts of 0.5% potassium chromate, 5% nickel sulphate and 1% cobalt chloride respectively. The fourth (control) patch was of petroleum jelly. Questionnaires were used to determine sex and history of any previous allergy to jewelry. After 48 hours, the patches were removed and results assessed. For each base metal, no statistically significant difference was found in the incidence of hypersensitivity reaction between the groups. Nor was there a significant difference in response found between metals, for all of the students tested. Although women were found to have a higher rate of nickel hypersensitivity than men, no such sex difference was found chromium and cobalt. No significant relationship was found between a history of allergy to jewelry and chromium hypersensitivity, however there was a significant difference for nickel and cobalt hypersensitivity. In confirmation of our tests, significant relationships were found between previous allergy histories and the respective patch test results."
1234663,Cohen et al. 1992,Forward mutations and DNA-protein crosslinks induced by ammonium metavanadate in cultured mammalian cells,"Ammonium metavanadate yielded a dose-dependent increase in mutation frequency at the V79 hprt locus following a 24-h exposure period in serum-free F12 medium. Vanadate also increased the mutation frequency of V79 cells by exposure of cells in salts-glucose medium, but these effects were not as striking, or as dose-dependent as they were in serum-free F12 medium. Ammonium metavanadate enhanced the mutation frequency in a V79 variant containing a transfected bacterial gpt gene. These cells are known to be more responsive to oxidative type mutations, and to mutations involving deletions. Although the absolute level of mutations was greater in these cells with ammonium metavanadate, so was the background, and these cells did not exhibit an enhanced mutagenic response to vanadate when compared to the wild-type V79 cells. The vanadate results were compared to a positive control potassium chromate, which exhibited a dose-dependent increase in mutation frequency. Ammonium metavanadate induced DNA-protein crosslinks formation in both Chinese hamster ovary and human MOLT4 cells, and the role of these relatively unrepaired genetic lesions in the mutations produced by vanadate and chromate are discussed.","Forward mutations and DNA-protein crosslinks induced by ammonium metavanadate in cultured mammalian cells Abs: Ammonium metavanadate yielded a dose-dependent increase in mutation frequency at the V79 hprt locus following a 24-h exposure period in serum-free F12 medium. Vanadate also increased the mutation frequency of V79 cells by exposure of cells in salts-glucose medium, but these effects were not as striking, or as dose-dependent as they were in serum-free F12 medium. Ammonium metavanadate enhanced the mutation frequency in a V79 variant containing a transfected bacterial gpt gene. These cells are known to be more responsive to oxidative type mutations, and to mutations involving deletions. Although the absolute level of mutations was greater in these cells with ammonium metavanadate, so was the background, and these cells did not exhibit an enhanced mutagenic response to vanadate when compared to the wild-type V79 cells. The vanadate results were compared to a positive control potassium chromate, which exhibited a dose-dependent increase in mutation frequency. Ammonium metavanadate induced DNA-protein crosslinks formation in both Chinese hamster ovary and human MOLT4 cells, and the role of these relatively unrepaired genetic lesions in the mutations produced by vanadate and chromate are discussed."
1234661,Castiglioni et al. 1992,Results of routine patch testing of 834 patients in Turin,"834 consecutive patients (630 female), aged between 26 and 46 years, who were suspected of having allergic contact dermatitis were patch tested with the GIRDCA standard series during 1989-1990. The most frequent sensitizers observed included nickel sulphate, cobalt, Kathon CG, perfumes, potassium dichromate and balsam of Peru. We have evaluated the influence of individual factors such as sex, age and occupation on the patch test results, and the coexistence of 2 or more unrelated but statistically significant sensitivities.","Results of routine patch testing of 834 patients in Turin Abs: 834 consecutive patients (630 female), aged between 26 and 46 years, who were suspected of having allergic contact dermatitis were patch tested with the GIRDCA standard series during 1989-1990. The most frequent sensitizers observed included nickel sulphate, cobalt, Kathon CG, perfumes, potassium dichromate and balsam of Peru. We have evaluated the influence of individual factors such as sex, age and occupation on the patch test results, and the coexistence of 2 or more unrelated but statistically significant sensitivities."
1234660,Lipozenci? et al. 1992,Contact allergy and psoriasis,"The study was conducted over a two-year period and included 48 psoriatic patients with palmar and plantar lesions and 61 psoriatic patients without palmar and plantar lesions who served as controls. The objective was to establish the incidence of contact sensitization and its importance as the causative factor in palmar and plantar psoriasis. The most frequent contact allergens were: nickel sulphate, mercapto mix, balsam of Peru, potassium dichromate, mercury mix and fragrance mix. Patch tests were positive in 41.7% psoriatics with palmar-plantar psoriasis and in only 6.6% of psoriatics without palmar-plantar involvement. The study showed an increased incidence of contact allergy in patients with palmar-plantar psoriasis.","Contact allergy and psoriasis Abs: The study was conducted over a two-year period and included 48 psoriatic patients with palmar and plantar lesions and 61 psoriatic patients without palmar and plantar lesions who served as controls. The objective was to establish the incidence of contact sensitization and its importance as the causative factor in palmar and plantar psoriasis. The most frequent contact allergens were: nickel sulphate, mercapto mix, balsam of Peru, potassium dichromate, mercury mix and fragrance mix. Patch tests were positive in 41.7% psoriatics with palmar-plantar psoriasis and in only 6.6% of psoriatics without palmar-plantar involvement. The study showed an increased incidence of contact allergy in patients with palmar-plantar psoriasis."
1234659,Urano et al. 1992,Vitamin E: inhibition of retinol-induced hemolysis and membrane-stabilizing behavior,"For the elucidation of the mechanism of membrane stabilization by vitamin E, the effects of alpha-tocopherol and its model compounds on either retinol-induced hemolysis of rabbit erythrocytes or the permeability and fluidity of liposomal membranes have been studied. Retinol-induced rabbit erythrocyte hemolysis has been found not to be caused by the oxidative disruption of erythrocyte membrane lipids initiated by retinol oxidation, but rather to arise from physical damage of the membrane micelle induced by penetration of retinol molecules. In suppressing hemolysis, alpha-tocopherol was more effective than other naturally occurring tocopherols. alpha-Tocopheryl acetate, nicotinate, and 6-deoxy-alpha-tocopherol were more effective than alpha-tocopherol itself. The inhibitory effects of alpha-tocopherol model compounds having side chains with at least two isoprene units or a long straight chain instead of the isoprenoid side chain were similar to those of alpha-tocopherol. These data suggest that for protection of membranes against retinol-induced damage, the hydroxyl group of alpha-tocopherol is not critical, but rather the chroman ring, three methyl groups on the aromatic ring, and the long side chain are necessary. To verify the mechanism of the inhibitory effect on hemolysis, not only the effect of vitamin E and its model compounds on the membrane permeability and fluidity, but also the mobility of alpha-tocopherol molecule in membranes has been investigated using bilayer liposomes as the model membranes. Addition of alpha-tocopherol to membranes produced a greater decrease in the permeability and fluidity of rat liver phosphatidylcholine liposomes compared with egg yolk phosphatidylcholine liposomes. In dipalmitoylphosphatidylcholine liposomes, however, alpha-tocopherol was less effective, that is, the more unsaturated the lipids, the more they interact with alpha-tocopherol. 2,2,5,7,8-Pentamethyl-6-chromanol with no isoprenoid side chain and phytol without the chromanol moiety had no effect. The measurement of 13C NMR relaxation times revealed that the mobility of methyl groups on the aromatic ring of alpha-tocopherol in membranes is significantly restricted. In contrast, the methyl groups at positions 4'a and 8'a on the isoprenoid side chain have high degrees of motional freedom in the lipid core of membranes. Furthermore, it was found that alpha-tocopherol in membranes interacts with chromate ions added as potassium chromate outside the membranes, resulting in an increase in membrane fluidity. These results are compatible with those of the inhibitory effect on retinol-induced erythrocyte hemolysis. On the basis of the results obtained here, a possible mechanism for membrane stabilization by vitamin E is proposed.","Vitamin E: inhibition of retinol-induced hemolysis and membrane-stabilizing behavior Abs: For the elucidation of the mechanism of membrane stabilization by vitamin E, the effects of alpha-tocopherol and its model compounds on either retinol-induced hemolysis of rabbit erythrocytes or the permeability and fluidity of liposomal membranes have been studied. Retinol-induced rabbit erythrocyte hemolysis has been found not to be caused by the oxidative disruption of erythrocyte membrane lipids initiated by retinol oxidation, but rather to arise from physical damage of the membrane micelle induced by penetration of retinol molecules. In suppressing hemolysis, alpha-tocopherol was more effective than other naturally occurring tocopherols. alpha-Tocopheryl acetate, nicotinate, and 6-deoxy-alpha-tocopherol were more effective than alpha-tocopherol itself. The inhibitory effects of alpha-tocopherol model compounds having side chains with at least two isoprene units or a long straight chain instead of the isoprenoid side chain were similar to those of alpha-tocopherol. These data suggest that for protection of membranes against retinol-induced damage, the hydroxyl group of alpha-tocopherol is not critical, but rather the chroman ring, three methyl groups on the aromatic ring, and the long side chain are necessary. To verify the mechanism of the inhibitory effect on hemolysis, not only the effect of vitamin E and its model compounds on the membrane permeability and fluidity, but also the mobility of alpha-tocopherol molecule in membranes has been investigated using bilayer liposomes as the model membranes. Addition of alpha-tocopherol to membranes produced a greater decrease in the permeability and fluidity of rat liver phosphatidylcholine liposomes compared with egg yolk phosphatidylcholine liposomes. In dipalmitoylphosphatidylcholine liposomes, however, alpha-tocopherol was less effective, that is, the more unsaturated the lipids, the more they interact with alpha-tocopherol. 2,2,5,7,8-Pentamethyl-6-chromanol with no isoprenoid side chain and phytol without the chromanol moiety had no effect. The measurement of 13C NMR relaxation times revealed that the mobility of methyl groups on the aromatic ring of alpha-tocopherol in membranes is significantly restricted. In contrast, the methyl groups at positions 4'a and 8'a on the isoprenoid side chain have high degrees of motional freedom in the lipid core of membranes. Furthermore, it was found that alpha-tocopherol in membranes interacts with chromate ions added as potassium chromate outside the membranes, resulting in an increase in membrane fluidity. These results are compatible with those of the inhibitory effect on retinol-induced erythrocyte hemolysis. On the basis of the results obtained here, a possible mechanism for membrane stabilization by vitamin E is proposed."
1234657,Alecu et al. 1992,Highly active effect of alpha interferon in blocking the cutaneous delayed hypersensitivity,"A group of 13 patients with contact dermatitis to various chemical compounds such as potassium dichromate, nickel sulphate, formaldehyde and balsam of Peru, was investigated by patch test and by the agreement between the history of disease and the patch test, the specific allergen involved in each special case could be demonstrated. Two-three days after the first patch test three normal skin areas were chosen. The first area was intradermally infiltrated with alpha-2a Interferon (IFN) (100,000 I.U. in 1 ml), the second area was infiltrated with saline and the third area, considered as control, did not receive any treatment. Once more the corresponding allergen was applied into the skin in a second patch-test. After 48 hours in the IFN infiltrated area, only the delayed contact hypersensitivity become negative thus proving that alpha-2a IFN behaves as an efficient inhibitor of these immune effector reactions. Since the lymphocytes involved in the delayed type hypersensitivity reactions (in our case contact dermatitis) belong to the T helper line, i.e., are CD-4 positive cells we conclude that alpha-2a IFN in vivo is an efficient inhibitor of the activation of these cells. This effect achieved by any CD-4(+) DTH clones does not depend on their antigenic specificity. Some clinical trials are now in progress in our laboratory to turn to account this important biological effect in the clinical practice as an efficient inhibitor in skin contact dermatitis.","Highly active effect of alpha interferon in blocking the cutaneous delayed hypersensitivity Abs: A group of 13 patients with contact dermatitis to various chemical compounds such as potassium dichromate, nickel sulphate, formaldehyde and balsam of Peru, was investigated by patch test and by the agreement between the history of disease and the patch test, the specific allergen involved in each special case could be demonstrated. Two-three days after the first patch test three normal skin areas were chosen. The first area was intradermally infiltrated with alpha-2a Interferon (IFN) (100,000 I.U. in 1 ml), the second area was infiltrated with saline and the third area, considered as control, did not receive any treatment. Once more the corresponding allergen was applied into the skin in a second patch-test. After 48 hours in the IFN infiltrated area, only the delayed contact hypersensitivity become negative thus proving that alpha-2a IFN behaves as an efficient inhibitor of these immune effector reactions. Since the lymphocytes involved in the delayed type hypersensitivity reactions (in our case contact dermatitis) belong to the T helper line, i.e., are CD-4 positive cells we conclude that alpha-2a IFN in vivo is an efficient inhibitor of the activation of these cells. This effect achieved by any CD-4(+) DTH clones does not depend on their antigenic specificity. Some clinical trials are now in progress in our laboratory to turn to account this important biological effect in the clinical practice as an efficient inhibitor in skin contact dermatitis."
1234656,Katsarou et al. 1992,Seasonal influence on patch test results in Greece,"Several studies have been reported on the suppressive effect of ultraviolet B (UVB), UVA sunlight and PUVA on contact dermatitis. However, studies that have tested the hypothesis that patch tests reactions have a seasonal variation due to the suppressive influence of sunlight, had found conflicting results. In order to clarify the influence of climate conditions in Athens, Greece (sunlight, temperature, latitude 38 degrees) on patch tests results, data from 5468 patch-tested patients (1978-1990) were analyzed for monthly, seasonal variation. In addition, 180 patients with a high degree of sun exposure due to occupation that were prospectively re-patch-tested in a different season (i.e. summer versus winter), with the same allergens and technique, were studied and analyzed statistically. Climate data was provided by the Hellenic National Meteorological Service. The results indicate that there is no significant influence on patch tests reactions in Athens, Greece. This may in part be due to the small differences in climate conditions that exist between summer and winter in Greece.","Seasonal influence on patch test results in Greece Abs: Several studies have been reported on the suppressive effect of ultraviolet B (UVB), UVA sunlight and PUVA on contact dermatitis. However, studies that have tested the hypothesis that patch tests reactions have a seasonal variation due to the suppressive influence of sunlight, had found conflicting results. In order to clarify the influence of climate conditions in Athens, Greece (sunlight, temperature, latitude 38 degrees) on patch tests results, data from 5468 patch-tested patients (1978-1990) were analyzed for monthly, seasonal variation. In addition, 180 patients with a high degree of sun exposure due to occupation that were prospectively re-patch-tested in a different season (i.e. summer versus winter), with the same allergens and technique, were studied and analyzed statistically. Climate data was provided by the Hellenic National Meteorological Service. The results indicate that there is no significant influence on patch tests reactions in Athens, Greece. This may in part be due to the small differences in climate conditions that exist between summer and winter in Greece."
1234655,Pozio et al. 1992,Cryptosporidium: different behaviour in calves of isolates of human origin,"The behaviour in calves of 3 Cryptosporidium human isolates was analysed in comparison with a bovine isolate. Twenty-four neonatal calves were infected. An isolate from a patient infected with human immunodeficiency virus (HIV) and showing mild cryptosporidiosis caused severe diarrhoea with a high production of oocysts in neonatal calves, as did a bovine isolate (group 1). Two human isolates, obtained from HIV patients with severe cryptosporidiosis, caused mild diarrhoea with low oocyst production in neonatal calves (group 2). The difference between the 2 groups in numbers of oocysts shed in calves was statistically significant (P = 0.005), as was the duration of oocyst shedding (P = 0.0004). Oocysts of group 2 isolates were less resistant to storage in 2% potassium dichromate at 4 degrees C than were oocysts of group 1. The biological and epidemiological implications are discussed.","Cryptosporidium: different behaviour in calves of isolates of human origin Abs: The behaviour in calves of 3 Cryptosporidium human isolates was analysed in comparison with a bovine isolate. Twenty-four neonatal calves were infected. An isolate from a patient infected with human immunodeficiency virus (HIV) and showing mild cryptosporidiosis caused severe diarrhoea with a high production of oocysts in neonatal calves, as did a bovine isolate (group 1). Two human isolates, obtained from HIV patients with severe cryptosporidiosis, caused mild diarrhoea with low oocyst production in neonatal calves (group 2). The difference between the 2 groups in numbers of oocysts shed in calves was statistically significant (P = 0.005), as was the duration of oocyst shedding (P = 0.0004). Oocysts of group 2 isolates were less resistant to storage in 2% potassium dichromate at 4 degrees C than were oocysts of group 1. The biological and epidemiological implications are discussed."
1234653,Gammelgaard et al. 1992,Permeation of chromium salts through human skin in vitro,Chromium permeation studies were performed on full thickness human skin in diffusion cells. All samples were analysed for the total chromium content by graphite furnace Zeeman-corrected atomic absorption spectrometry. Some samples were analysed by an ion chromatographic method permitting the simultaneous determination of Cr(VI) and Cr(III) as well. The amounts of chromium found in all skin layers were significantly higher when potassium dichromate was applied to the skin compared with chromium chloride or chromium nitrate. Chromium could only be detected in the recipient phase after application of the dichromate solution. Chromium skin levels increased with increasing concentrations of applied chromium salts up to 0.034 M Cr. The amount of chromium in recipient phase and skin layers increased with increasing pH when the applied solution contained potassium dichromate. This was ascribed to a decreased skin barrier function of the skin. The amount of chromium found in all skin layers after application of chromium chloride decreased with increasing pH due to lower solubility of the salt. The % of chromium found in the recipient phase as chromium(VI) increased with increasing total chromium concentration indicating a limited reduction ability of the skin in vitro.,Permeation of chromium salts through human skin in vitro Abs: Chromium permeation studies were performed on full thickness human skin in diffusion cells. All samples were analysed for the total chromium content by graphite furnace Zeeman-corrected atomic absorption spectrometry. Some samples were analysed by an ion chromatographic method permitting the simultaneous determination of Cr(VI) and Cr(III) as well. The amounts of chromium found in all skin layers were significantly higher when potassium dichromate was applied to the skin compared with chromium chloride or chromium nitrate. Chromium could only be detected in the recipient phase after application of the dichromate solution. Chromium skin levels increased with increasing concentrations of applied chromium salts up to 0.034 M Cr. The amount of chromium in recipient phase and skin layers increased with increasing pH when the applied solution contained potassium dichromate. This was ascribed to a decreased skin barrier function of the skin. The amount of chromium found in all skin layers after application of chromium chloride decreased with increasing pH due to lower solubility of the salt. The % of chromium found in the recipient phase as chromium(VI) increased with increasing total chromium concentration indicating a limited reduction ability of the skin in vitro.
1234652,Elberger et al. 1992,HRP reacted with the chromogen o-tolidine produces whole-cell reaction product at light and electron microscope levels: negative effects of sucrose and Golgi staining on benzidine reactions,"Studies of pathway microcircuitry often require electron microscope analysis. To facilitate these analyses, methods for labeling cells in their entirety are extremely useful. Furthermore, such a method would be most useful if the label would be completely confined by the cell membrane so that second labels for synapse identification could be used. No existing method reliably and repeatably produces this kind of a result. In seeking to develop such a method, a seldom-used chromogen for horseradish peroxidase (HRP) was found which produced superlative results for light and electron microscope analysis. o-Tolidine (3,3'-dimethylbenzidine) reacted with HRP produces a very electron-dense reaction product distributed uniformly throughout the cytoplasm and nucleoplasm; membranes are unobscured so that mitochondria, lysosomes, Golgi apparati and endoplasmic reticula are well defined. The reaction product extends into cellular processes of all sizes, including processes with cell bodies not within the plane of section, and is easily visualized at even the lowest electron microscope magnification. The HRP reaction product is completely confined by the cell membrane, thus terminals presynaptic to labeled cells remain distinct. However, the o-tolidine/HRP reaction product is negatively affected by exposure to oxidizers. In tissue exposed to sucrose before or after being reacted with o-tolidine, the HRP reaction product is less electron dense and is found only in lysosomes outside the nucleus or occasionally in proximal cellular processes. The o-tolidine/HRP reaction product is similarly affected when exposed to potassium dichromate for Golgi staining. For some other benzidine compounds, the chromogen/HRP reaction product is also negatively affected by exposure to these chemicals. Therefore, o-tolidine is a superior chromogen for HRP, labeling cells with details similar to that found for cells intracellularly injected with HRP.","HRP reacted with the chromogen o-tolidine produces whole-cell reaction product at light and electron microscope levels: negative effects of sucrose and Golgi staining on benzidine reactions Abs: Studies of pathway microcircuitry often require electron microscope analysis. To facilitate these analyses, methods for labeling cells in their entirety are extremely useful. Furthermore, such a method would be most useful if the label would be completely confined by the cell membrane so that second labels for synapse identification could be used. No existing method reliably and repeatably produces this kind of a result. In seeking to develop such a method, a seldom-used chromogen for horseradish peroxidase (HRP) was found which produced superlative results for light and electron microscope analysis. o-Tolidine (3,3'-dimethylbenzidine) reacted with HRP produces a very electron-dense reaction product distributed uniformly throughout the cytoplasm and nucleoplasm; membranes are unobscured so that mitochondria, lysosomes, Golgi apparati and endoplasmic reticula are well defined. The reaction product extends into cellular processes of all sizes, including processes with cell bodies not within the plane of section, and is easily visualized at even the lowest electron microscope magnification. The HRP reaction product is completely confined by the cell membrane, thus terminals presynaptic to labeled cells remain distinct. However, the o-tolidine/HRP reaction product is negatively affected by exposure to oxidizers. In tissue exposed to sucrose before or after being reacted with o-tolidine, the HRP reaction product is less electron dense and is found only in lysosomes outside the nucleus or occasionally in proximal cellular processes. The o-tolidine/HRP reaction product is similarly affected when exposed to potassium dichromate for Golgi staining. For some other benzidine compounds, the chromogen/HRP reaction product is also negatively affected by exposure to these chemicals. Therefore, o-tolidine is a superior chromogen for HRP, labeling cells with details similar to that found for cells intracellularly injected with HRP."
1234651,Spacek 1992,Dynamics of Golgi impregnation in neurons,"This paper describes the early stages of impregnation by the Golgi rapid method in sections and blocks of brain tissue. Aldehyde-fixed and potassium dichromate-treated sections of cerebral cortex were placed on glass slides and coverslipped. The dichromate solution was then replaced by a silver nitrate solution, and events taking place in the section were monitored and time-lapse recorded until the impregnation was interrupted and the sections subsequently prepared for electron microscopy. The tissue blocks, fixed and chromated in the same way, were placed into a silver nitrate solution for 30 min to 24 h and the progress of impregnation compared with the results obtained in the sections on the glass slides. Two basic modes of impregnation were observed, apparently in direct relation to the process of crystallization of silver chromate: crystals of silver chromate growing directly from the surface of the tissue into the nerve cell via its transected plasma membranes, and microcrystalline precipitate of silver chromate spreading into the nerve cell from nucleation centres dispersed in the tissue. The precipitate grows inside the cell as in a preformed channel until the cell has been filled. If the nucleation begins extracellularly, the precipitate extends into the narrow intercellular gaps. Electron microscopy showed that the crystalline precipitate consisted of multilamellar formations containing dense coalesced granules that did not cross plasma or endocellular membrane boundaries.","Dynamics of Golgi impregnation in neurons Abs: This paper describes the early stages of impregnation by the Golgi rapid method in sections and blocks of brain tissue. Aldehyde-fixed and potassium dichromate-treated sections of cerebral cortex were placed on glass slides and coverslipped. The dichromate solution was then replaced by a silver nitrate solution, and events taking place in the section were monitored and time-lapse recorded until the impregnation was interrupted and the sections subsequently prepared for electron microscopy. The tissue blocks, fixed and chromated in the same way, were placed into a silver nitrate solution for 30 min to 24 h and the progress of impregnation compared with the results obtained in the sections on the glass slides. Two basic modes of impregnation were observed, apparently in direct relation to the process of crystallization of silver chromate: crystals of silver chromate growing directly from the surface of the tissue into the nerve cell via its transected plasma membranes, and microcrystalline precipitate of silver chromate spreading into the nerve cell from nucleation centres dispersed in the tissue. The precipitate grows inside the cell as in a preformed channel until the cell has been filled. If the nucleation begins extracellularly, the precipitate extends into the narrow intercellular gaps. Electron microscopy showed that the crystalline precipitate consisted of multilamellar formations containing dense coalesced granules that did not cross plasma or endocellular membrane boundaries."
1234649,Jonker et al. 1993,Acute (24 hr) toxicity of a combination of four nephrotoxicants in rats compared with the toxicity of the individual compounds,"To identify possible hazards of combined exposure to chemicals with the same target organ, a 24-hr single dose experiment was carried out in which the renal toxicity of mercuric chloride, potassium dichromate, d-limonene and hexachloro-1:3-butadiene administered simultaneously was compared with the nephrotoxicity of the individual compounds, using a total of 11 groups each consisting of five 12-wk-old male Wistar rats. The dose levels used were based on the results of a range-finding study with the individual compounds in the same strain of rats kept under similar experimental conditions, and comprised the 'Minimum-Nephrotoxic-Effect Level' (MNEL) and the 'No-Nephrotoxic-Effect Level' (NNEL) of each of the four compounds alone and in combination. A group of vehicle-treated rats served as controls. At the MNEL of the combination, antagonism of effects was encountered, seen for example as less severely increased activity of gamma-glutamyl transferase in the urine. Synergism of effects was also observed, for example increased severity of renal tubular necrosis, and more markedly increased activity of urinary lysozyme, lactate dehydrogenase, alkaline phosphatase and N-acetyl-beta-glucosaminidase. More importantly, however, at the NNEL of the combination no signs of impaired renal function or renal damage were observed, suggesting absence of both dose additivity and potentiating interaction at the tested subeffective levels of the individual nephrotoxicants.","Acute (24 hr) toxicity of a combination of four nephrotoxicants in rats compared with the toxicity of the individual compounds Abs: To identify possible hazards of combined exposure to chemicals with the same target organ, a 24-hr single dose experiment was carried out in which the renal toxicity of mercuric chloride, potassium dichromate, d-limonene and hexachloro-1:3-butadiene administered simultaneously was compared with the nephrotoxicity of the individual compounds, using a total of 11 groups each consisting of five 12-wk-old male Wistar rats. The dose levels used were based on the results of a range-finding study with the individual compounds in the same strain of rats kept under similar experimental conditions, and comprised the 'Minimum-Nephrotoxic-Effect Level' (MNEL) and the 'No-Nephrotoxic-Effect Level' (NNEL) of each of the four compounds alone and in combination. A group of vehicle-treated rats served as controls. At the MNEL of the combination, antagonism of effects was encountered, seen for example as less severely increased activity of gamma-glutamyl transferase in the urine. Synergism of effects was also observed, for example increased severity of renal tubular necrosis, and more markedly increased activity of urinary lysozyme, lactate dehydrogenase, alkaline phosphatase and N-acetyl-beta-glucosaminidase. More importantly, however, at the NNEL of the combination no signs of impaired renal function or renal damage were observed, suggesting absence of both dose additivity and potentiating interaction at the tested subeffective levels of the individual nephrotoxicants."
1234648,Matsui et al. 1993,Infectivity and sporogony of Caryospora-type oocysts of Isospora rivolta obtained by heating,"The infectivity and sporogony of Caryospora-type oocysts of Isospora rivolta obtained by heat treatment were examined. Fresh unsporulated oocysts of I. rivolta were heated at 50 degrees C for 5 min, then poured into a cold 2% potassium dichromate solution and incubated at 25 degrees C. To observe the stage of sporulation, 100 oocysts were examined at 2-h intervals after incubation. The earliest sporulated oocysts were observed at 14 h and the sporulation time was 22 h, similar to that of nontreated oocysts. To determine the infectivity, only Caryospora-type oocysts were collected after sporulation and inoculated orally into cats and mice. The mice were killed at 7 days after inoculation, and their mesenteric lymph nodes and spleens were fed to other cats. All of these cats shed oocysts. The newly discharged oocysts developed into the Isospora type after sporulation. These results suggest that the Caryospora-type oocysts transformed only morphologically after heat treatment and were as infective as the nontreated oocysts to host animals.","Infectivity and sporogony of Caryospora-type oocysts of Isospora rivolta obtained by heating Abs: The infectivity and sporogony of Caryospora-type oocysts of Isospora rivolta obtained by heat treatment were examined. Fresh unsporulated oocysts of I. rivolta were heated at 50 degrees C for 5 min, then poured into a cold 2% potassium dichromate solution and incubated at 25 degrees C. To observe the stage of sporulation, 100 oocysts were examined at 2-h intervals after incubation. The earliest sporulated oocysts were observed at 14 h and the sporulation time was 22 h, similar to that of nontreated oocysts. To determine the infectivity, only Caryospora-type oocysts were collected after sporulation and inoculated orally into cats and mice. The mice were killed at 7 days after inoculation, and their mesenteric lymph nodes and spleens were fed to other cats. All of these cats shed oocysts. The newly discharged oocysts developed into the Isospora type after sporulation. These results suggest that the Caryospora-type oocysts transformed only morphologically after heat treatment and were as infective as the nontreated oocysts to host animals."
1234647,Korallus et al. 1993,Bronchial carcinoma mortality in the German chromate-producing industry: the effects of process modification,"This study updates a 1982 report on mortality at two German chromate-producing factories. The main objective of the study was to establish whether the change-over to a production process using lime-free conversion of chromite ore, thus eliminating the formation of calcium chromate, had resulted in a distinct reduction in bronchial carcinoma mortality among workers exposed for the first time after the change-over (completed in 1958 in Leverkusen and 1964 in Uerdingen). A total of 1417 workers with at least 1 year of exposure were enrolled in the study. The observation period ended on 31 December 1988. The expected number of deaths was calculated using population statistics for North Rhine-Westphalia. The risk was determined in the form of a standardised mortality ratio (SMR), i.e. the ratio of observed deaths to expected deaths. In the group of 739 workers exposed before the process change-over was completed, 432 died during the observation period, 66 of them from bronchial carcinoma. This significant excess produced an SMR of 2.27 (95% confidence interval: 1.78-2.85). Where the cause of death was unknown, cases were allocated to a cause of death on the basis of the percentage occurrence of various causes of death in the specific subcohort. The cohort of 678 workers first exposed after the process modification had been completed had a slightly increased SMR for lung cancer of 1.26 (95% confidence interval: 0.58-2.38) based on nine cases.(ABSTRACT TRUNCATED AT 250 WORDS)","Bronchial carcinoma mortality in the German chromate-producing industry: the effects of process modification Abs: This study updates a 1982 report on mortality at two German chromate-producing factories. The main objective of the study was to establish whether the change-over to a production process using lime-free conversion of chromite ore, thus eliminating the formation of calcium chromate, had resulted in a distinct reduction in bronchial carcinoma mortality among workers exposed for the first time after the change-over (completed in 1958 in Leverkusen and 1964 in Uerdingen). A total of 1417 workers with at least 1 year of exposure were enrolled in the study. The observation period ended on 31 December 1988. The expected number of deaths was calculated using population statistics for North Rhine-Westphalia. The risk was determined in the form of a standardised mortality ratio (SMR), i.e. the ratio of observed deaths to expected deaths. In the group of 739 workers exposed before the process change-over was completed, 432 died during the observation period, 66 of them from bronchial carcinoma. This significant excess produced an SMR of 2.27 (95% confidence interval: 1.78-2.85). Where the cause of death was unknown, cases were allocated to a cause of death on the basis of the percentage occurrence of various causes of death in the specific subcohort. The cohort of 678 workers first exposed after the process modification had been completed had a slightly increased SMR for lung cancer of 1.26 (95% confidence interval: 0.58-2.38) based on nine cases.(ABSTRACT TRUNCATED AT 250 WORDS)"
1234646,Cohen et al. 1993,Induction of type 2 salivary cystatin in immunological and chemical kidney injury,"We have previously reported that isoproterenol induces type 2 salivary cystatin in both submandibular glands and kidney tubule cells of rats but not in any other organs examined. In the present study, we investigated whether this salivary protein is induced in other conditions that show kidney tubule injury. Immunocytochemistry, using a monospecific antiserum to this cystatin, revealed specific staining within the proximal tubule epithelium of the cortex as well as in the inner and outer stripe of the medulla of immunologically and chemically injured rats. Cystatin could not be detected in kidneys from healthy rats by means of immunocytochemistry. Weak staining was found in 3/3 kidneys of rats treated with turpentine and in 5/5 animals treated with potassium dichromate. In rats treated with puromycin, cystatin could not be demonstrated in 5/5 animals having proteinuria of less than 100 mg/24 h; however, moderate staining was observed in 4/5 puromycin-treated rats having proteinuria greater than 100 mg/24 h. In Heymann nephritis, cystatin was present in 7/31 kidneys with proteinuria lasting 6 to 15 weeks and in none (0/7) with proteinuria of shorter duration. Strong staining was also observed in 10/10 kidneys from rats with moderate-to-severe chronic serum sickness. This study shows that elaboration of type 2 cystatin in rats is not limited to salivary glands and, with our previous study, suggests that induction of this cysteine inhibitor may represent a local response to generalized tissue injury in both submandibular and renal tissues. These findings further demonstrate that induction of cystatin in salivary glands is not unique to these glands and suggest that induction of this cysteine proteinase inhibitor may represent a local response to tissue injury caused by diverse mechanisms.","Induction of type 2 salivary cystatin in immunological and chemical kidney injury Abs: We have previously reported that isoproterenol induces type 2 salivary cystatin in both submandibular glands and kidney tubule cells of rats but not in any other organs examined. In the present study, we investigated whether this salivary protein is induced in other conditions that show kidney tubule injury. Immunocytochemistry, using a monospecific antiserum to this cystatin, revealed specific staining within the proximal tubule epithelium of the cortex as well as in the inner and outer stripe of the medulla of immunologically and chemically injured rats. Cystatin could not be detected in kidneys from healthy rats by means of immunocytochemistry. Weak staining was found in 3/3 kidneys of rats treated with turpentine and in 5/5 animals treated with potassium dichromate. In rats treated with puromycin, cystatin could not be demonstrated in 5/5 animals having proteinuria of less than 100 mg/24 h; however, moderate staining was observed in 4/5 puromycin-treated rats having proteinuria greater than 100 mg/24 h. In Heymann nephritis, cystatin was present in 7/31 kidneys with proteinuria lasting 6 to 15 weeks and in none (0/7) with proteinuria of shorter duration. Strong staining was also observed in 10/10 kidneys from rats with moderate-to-severe chronic serum sickness. This study shows that elaboration of type 2 cystatin in rats is not limited to salivary glands and, with our previous study, suggests that induction of this cysteine inhibitor may represent a local response to generalized tissue injury in both submandibular and renal tissues. These findings further demonstrate that induction of cystatin in salivary glands is not unique to these glands and suggest that induction of this cysteine proteinase inhibitor may represent a local response to tissue injury caused by diverse mechanisms."
1234640,Ren et al. 1993,A sequential study on the use of the cytokinesis-block micronucleus method in mouse splenocytes,"Several known clastogens and mutagens have been tested for their ability to induce micronuclei (MN) using the cytokinesis-block method in mouse splenocytes. The chemicals were harringtonine, cisplatin, cytosine arabinoside, vincristine sulfate, colchicine, potassium chromate, methyl methanesulfonate and 2-acetylaminofluorene. All chemicals tested induced a dose-dependent increase in MN and a delay in cell-cycle progression. The results suggest that the cytokinesis-block micronucleus method in mouse splenocytes is reliable, economical and sensitive enough for detecting mutagenic agents in vivo and in vitro.","A sequential study on the use of the cytokinesis-block micronucleus method in mouse splenocytes Abs: Several known clastogens and mutagens have been tested for their ability to induce micronuclei (MN) using the cytokinesis-block method in mouse splenocytes. The chemicals were harringtonine, cisplatin, cytosine arabinoside, vincristine sulfate, colchicine, potassium chromate, methyl methanesulfonate and 2-acetylaminofluorene. All chemicals tested induced a dose-dependent increase in MN and a delay in cell-cycle progression. The results suggest that the cytokinesis-block micronucleus method in mouse splenocytes is reliable, economical and sensitive enough for detecting mutagenic agents in vivo and in vitro."
1234639,Cohen et al. 1993,Induction of type 2 cystatin in rat submandibular glands by systemically administered agents,"An inducible type 2 cystatin has earlier been characterized in submandibular glands and kidneys of rats treated with isoproterenol, as well as in kidneys of rats with experimental renal disease. The purpose now was to determine whether giving agents that have systemic toxicity could also be associated with induction of cystatin in rat salivary glands. Female Wistar rats (200-250 g) were given isoproterenol, cyclocytidine, potassium dichromate or turpentine oil. After autopsy, the organs were sectioned, fixed in 10% formalin, and processed routinely. Paraffin sections were processed for both the peroxidase-antiperoxidase and the avidin-biotin-alkaline phosphatase immunocytochemical methods. The submandibular glands of rats given cyclocytidine had generalized, strong staining of acinar cells, as well as occasional weak staining within granular convoluted tubules. Animals given either potassium dichromate or turpentine oil exhibited moderate staining for cystatin in submandibular acini. Rats given isoproterenol as a positive control exhibited strong acinar staining throughout the submandibular gland, while the glands of untreated rats were unreactive. Inducible type 2 cystatin could not be detected in the parotid or sublingual glands, or in trachea, lung, stomach, small intestine, large intestine, spleen, liver and pancreas, after treatment with any of the systemic agents evaluated. The results indicate that elaboration of type 2 cystatin can be induced by a variety of systemically administered agents other than isoproterenol, and suggest that elaboration of type 2 cystatin may represent a more generalized response to tissue injury.","Induction of type 2 cystatin in rat submandibular glands by systemically administered agents Abs: An inducible type 2 cystatin has earlier been characterized in submandibular glands and kidneys of rats treated with isoproterenol, as well as in kidneys of rats with experimental renal disease. The purpose now was to determine whether giving agents that have systemic toxicity could also be associated with induction of cystatin in rat salivary glands. Female Wistar rats (200-250 g) were given isoproterenol, cyclocytidine, potassium dichromate or turpentine oil. After autopsy, the organs were sectioned, fixed in 10% formalin, and processed routinely. Paraffin sections were processed for both the peroxidase-antiperoxidase and the avidin-biotin-alkaline phosphatase immunocytochemical methods. The submandibular glands of rats given cyclocytidine had generalized, strong staining of acinar cells, as well as occasional weak staining within granular convoluted tubules. Animals given either potassium dichromate or turpentine oil exhibited moderate staining for cystatin in submandibular acini. Rats given isoproterenol as a positive control exhibited strong acinar staining throughout the submandibular gland, while the glands of untreated rats were unreactive. Inducible type 2 cystatin could not be detected in the parotid or sublingual glands, or in trachea, lung, stomach, small intestine, large intestine, spleen, liver and pancreas, after treatment with any of the systemic agents evaluated. The results indicate that elaboration of type 2 cystatin can be induced by a variety of systemically administered agents other than isoproterenol, and suggest that elaboration of type 2 cystatin may represent a more generalized response to tissue injury."
1234638,Fernández Vozmediano et al. 1993,Comparison of TRUE Test and Finn Chambers in construction workers,"A study of the ability of the TRUE test to detect chromate allergy in construction workers was conducted. Eight construction workers (group-A) with previously confirmed chromate allergic contact dermatitis were patch tested with potassium-dichromate (7778509) using the TRUE and Finn Chambers techniques. Another 14 construction workers (group-B) with chromate dermatitis were also patch tested with potassium-dichromate using the TRUE technique. Along side the TRUE panel, open patches of potassium-dichromate were also applied. Forty seven dermatology patients, seven of whom were construction workers (group-C), were patch tested with potassium-dichromate using the TRUE and Finn Chambers techniques. The test sites were examined 2 and 4 days after application of potassium-dichromate and scored according to International Contact Dermatitis Research Group recommendations. All patients in group-A and group-B with chromate allergy reacted positively when tested by the Finn Chambers and open patch techniques. When tested by the TRUE technique, only 37.2% of the subjects in group-A and 50% in group-B reacted positively. When the strength of the reactions obtained by the TRUE technique was considered, 25% of the positive reactions in the group-A patients and 50% of the positive reactions in group-B subjects were only mildly positive. In group-C, 87.5% of the subjects reacted positively to both tests. The authors conclude that the TRUE test and the Finn Chambers techniques produce a significant proportion of discordant results.","Comparison of TRUE Test and Finn Chambers in construction workers Abs: A study of the ability of the TRUE test to detect chromate allergy in construction workers was conducted. Eight construction workers (group-A) with previously confirmed chromate allergic contact dermatitis were patch tested with potassium-dichromate (7778509) using the TRUE and Finn Chambers techniques. Another 14 construction workers (group-B) with chromate dermatitis were also patch tested with potassium-dichromate using the TRUE technique. Along side the TRUE panel, open patches of potassium-dichromate were also applied. Forty seven dermatology patients, seven of whom were construction workers (group-C), were patch tested with potassium-dichromate using the TRUE and Finn Chambers techniques. The test sites were examined 2 and 4 days after application of potassium-dichromate and scored according to International Contact Dermatitis Research Group recommendations. All patients in group-A and group-B with chromate allergy reacted positively when tested by the Finn Chambers and open patch techniques. When tested by the TRUE technique, only 37.2% of the subjects in group-A and 50% in group-B reacted positively. When the strength of the reactions obtained by the TRUE technique was considered, 25% of the positive reactions in the group-A patients and 50% of the positive reactions in group-B subjects were only mildly positive. In group-C, 87.5% of the subjects reacted positively to both tests. The authors conclude that the TRUE test and the Finn Chambers techniques produce a significant proportion of discordant results."
1234637,Huggins and  Henion 1993,Capillary electrophoresis/mass spectrometry determination of inorganic ions using an ion spray-sheath flow interface,"The determination of inorganic cations and anions by capillary electrophoresis/mass spectrometry (CE/MS) is reported using an ion spray-sheath flow interface coupling. A twelve-component synthetic mixture of cations which included the positive ions of K, Ba, Ca, Mn, Cd, Co, Pb, Cr, Ni, Zn, Ag, and Cu was loaded into the capillary column at levels ranging from 30 to 300 pg, separated by CE, and detected by indirect UV and in the full-scan (m/z 35-450) positive ion CE/MS mode using an aqueous buffer containing 30 mM creatinine and 8 mM alpha-hydroxyisobutyric acid, pH 4.8. Creatinine forms adducts with the cations which are observed in the gas phase and requires rather high (120 electron volts) declustering energy to dissociate. This produces a reduction in charge state to form the free, singly charged, inorganic cations which are observed in the mass spectra. CE/MS analysis of an aqueous acidic extract of used aircraft engine oil revealed high levels of lead as well as lower levels of chromium and nickel. CE-indirect UV analysis of a synthetic mixture containing 300 pg each of 11 inorganic ions, which included the anions of Br, Cl, NO2, NO3, S2O3, N3, SCN, SO4, SeO4, oxalate, and MoO4, is shown. The running buffer which affected this separation contained 5 mM ammonium dichromate, 10 mM ammonium acetate, and 20 mM diethylenetriamine at pH 9.3. Although indirect UV detection revealed good separation of these anions, CE/MS analysis of this mixture was complicated by interfering ion current signals from the cluster ions formed by the interaction between the additives and the analytes.(ABSTRACT TRUNCATED AT 250 WORDS)","Capillary electrophoresis/mass spectrometry determination of inorganic ions using an ion spray-sheath flow interface Abs: The determination of inorganic cations and anions by capillary electrophoresis/mass spectrometry (CE/MS) is reported using an ion spray-sheath flow interface coupling. A twelve-component synthetic mixture of cations which included the positive ions of K, Ba, Ca, Mn, Cd, Co, Pb, Cr, Ni, Zn, Ag, and Cu was loaded into the capillary column at levels ranging from 30 to 300 pg, separated by CE, and detected by indirect UV and in the full-scan (m/z 35-450) positive ion CE/MS mode using an aqueous buffer containing 30 mM creatinine and 8 mM alpha-hydroxyisobutyric acid, pH 4.8. Creatinine forms adducts with the cations which are observed in the gas phase and requires rather high (120 electron volts) declustering energy to dissociate. This produces a reduction in charge state to form the free, singly charged, inorganic cations which are observed in the mass spectra. CE/MS analysis of an aqueous acidic extract of used aircraft engine oil revealed high levels of lead as well as lower levels of chromium and nickel. CE-indirect UV analysis of a synthetic mixture containing 300 pg each of 11 inorganic ions, which included the anions of Br, Cl, NO2, NO3, S2O3, N3, SCN, SO4, SeO4, oxalate, and MoO4, is shown. The running buffer which affected this separation contained 5 mM ammonium dichromate, 10 mM ammonium acetate, and 20 mM diethylenetriamine at pH 9.3. Although indirect UV detection revealed good separation of these anions, CE/MS analysis of this mixture was complicated by interfering ion current signals from the cluster ions formed by the interaction between the additives and the analytes.(ABSTRACT TRUNCATED AT 250 WORDS)"
1234636,Saha et al. 1993,Footwear dermatitis,"We conducted a study to determine the prevalence and clinical patterns of footwear dermatitis, patch testing 50 patients with suspected footwear dermatitis and 30 controls with 22 allergens of a shoe series (Chemotechnique Diagnostics AB, Malmö, Sweden). The overall prevalence among contact dermatitis cases was 11.7%. The dorsa of the feet and toes were the commonest sites involved. 70% of patients showed sensitivity to footwear allergen(s), as opposed to 6.67% of controls. Potassium dichromate and colophony were the commonest sensitizers. Other sensitizers were the rubber accelerators 2-mercaptobenzothiazole (MBT) and diphenylguanidine (DPG) and a dye p-aminoazobenzene. Of the 23 patients patch tested with pieces or scrapings of footwear, only 3 showed positive reactions. We recommend that there should be primary and secondary footwear screening series to detect the responsible allergens, with the ultimate objective of providing correct nonallergenic footwear for our patients, with the help of manufacturers and research institutes.","Footwear dermatitis Abs: We conducted a study to determine the prevalence and clinical patterns of footwear dermatitis, patch testing 50 patients with suspected footwear dermatitis and 30 controls with 22 allergens of a shoe series (Chemotechnique Diagnostics AB, Malmö, Sweden). The overall prevalence among contact dermatitis cases was 11.7%. The dorsa of the feet and toes were the commonest sites involved. 70% of patients showed sensitivity to footwear allergen(s), as opposed to 6.67% of controls. Potassium dichromate and colophony were the commonest sensitizers. Other sensitizers were the rubber accelerators 2-mercaptobenzothiazole (MBT) and diphenylguanidine (DPG) and a dye p-aminoazobenzene. Of the 23 patients patch tested with pieces or scrapings of footwear, only 3 showed positive reactions. We recommend that there should be primary and secondary footwear screening series to detect the responsible allergens, with the ultimate objective of providing correct nonallergenic footwear for our patients, with the help of manufacturers and research institutes."
1234635,Sultan 1993,"Computer assisted optimization of a flow-injection method for the assay of promethazine, chlorpromazine and trimeprazine in drug formulations","A simple, accurate and fast method for the determination of promethazine, chlorpromazine and trimeprazine neuroleptics in drug formulations by flow injection spectrophotometric detection was developed. The method was based on the oxidation of the drug with potassium dichromate in sulphuric acid media. Optimum conditions were obtained by using the modified simplex computer programme. A 110-mul sample volume was taken as reasonable for all the compounds. The optimum conditions reached were 76-cm coil length, 6.00 ml/min flow rate, 3.10M sulphuric acid and 0.00167M dichromate for promethazine; 94-cm coil length, 5.00 ml/min flow rate, 1.48M sulphuric acid and 0.00185M dichromate for chlorpromethazine and 80-cm coil length, 6.00 ml/min flow rate, 3.44M sulphuric acid and 0.000500M dichromate for trimeprazine. High sample throughput of at least 200 samples per hour was obtained for all compounds. Acceptable relative standard deviations in the range +/-0.4-0.9%, and good accuracy in the range 99.5-99.9% were attained when the method was statistically compared with the BP method and when applied to proprietary drugs, without suffering interferences.","Computer assisted optimization of a flow-injection method for the assay of promethazine, chlorpromazine and trimeprazine in drug formulations Abs: A simple, accurate and fast method for the determination of promethazine, chlorpromazine and trimeprazine neuroleptics in drug formulations by flow injection spectrophotometric detection was developed. The method was based on the oxidation of the drug with potassium dichromate in sulphuric acid media. Optimum conditions were obtained by using the modified simplex computer programme. A 110-mul sample volume was taken as reasonable for all the compounds. The optimum conditions reached were 76-cm coil length, 6.00 ml/min flow rate, 3.10M sulphuric acid and 0.00167M dichromate for promethazine; 94-cm coil length, 5.00 ml/min flow rate, 1.48M sulphuric acid and 0.00185M dichromate for chlorpromethazine and 80-cm coil length, 6.00 ml/min flow rate, 3.44M sulphuric acid and 0.000500M dichromate for trimeprazine. High sample throughput of at least 200 samples per hour was obtained for all compounds. Acceptable relative standard deviations in the range +/-0.4-0.9%, and good accuracy in the range 99.5-99.9% were attained when the method was statistically compared with the BP method and when applied to proprietary drugs, without suffering interferences."
1234634,Ortega et al. 1993,Cyclospora species--a new protozoan pathogen of humans,"<strong>BACKGROUND: </strong>Organisms referred to as &quot;cyanobacterium-like bodies&quot; have now been identified worldwide in the feces of both immunocompetent and immunocompromised patients with diarrhea. Organisms with a similar appearance have been isolated from Peruvian patients since 1985. From 1988 to 1991 we studied prospectively two cohorts of infants and young children infected with this organism. We now attempt to identify it.<br /><br /><strong>METHODS: </strong>Fecal samples were collected weekly from the children and examined with the use of acid-fast staining and staining with a monoclonal antibody specific for cryptosporidium. Stools positive for cyanobacterium-like bodies were preserved in potassium dichromate and exposed to conditions allowing coccidian sporulation and excystation. Both unsporulated and sporulated oocysts were fixed by freeze-substitution techniques and then examined by electron microscopy.<br /><br /><strong>RESULTS: </strong>Organisms isolated from the feces of Peruvian patients and two patients from the United States were identified as belonging to the coccidian genus cyclospora, after sporulation and excystation of the oocysts according to standard techniques. Complete sporulation occurred within 5 to 13 days in oocysts maintained in potassium dichromate at 25 or 32 degrees C. Complete excystation resulted in the liberation of two sporozoites from the two sporocysts within each oocyst (cryptosporidia have four naked sporozoites within each oocyst). The presence of organelles characteristic of coccidian organisms was confirmed by electron microscopy.<br /><br /><strong>CONCLUSIONS: </strong>We have identified organisms of the genus cyclospora that are remarkably similar to cryptosporidia in their morphologic features and the diarrheal disease that they produce in humans. The complete life cycle and epidemiology of this new protozoan parasite remain to be described.","Cyclospora species--a new protozoan pathogen of humans Abs: <strong>BACKGROUND: </strong>Organisms referred to as &quot;cyanobacterium-like bodies&quot; have now been identified worldwide in the feces of both immunocompetent and immunocompromised patients with diarrhea. Organisms with a similar appearance have been isolated from Peruvian patients since 1985. From 1988 to 1991 we studied prospectively two cohorts of infants and young children infected with this organism. We now attempt to identify it.<br /><br /><strong>METHODS: </strong>Fecal samples were collected weekly from the children and examined with the use of acid-fast staining and staining with a monoclonal antibody specific for cryptosporidium. Stools positive for cyanobacterium-like bodies were preserved in potassium dichromate and exposed to conditions allowing coccidian sporulation and excystation. Both unsporulated and sporulated oocysts were fixed by freeze-substitution techniques and then examined by electron microscopy.<br /><br /><strong>RESULTS: </strong>Organisms isolated from the feces of Peruvian patients and two patients from the United States were identified as belonging to the coccidian genus cyclospora, after sporulation and excystation of the oocysts according to standard techniques. Complete sporulation occurred within 5 to 13 days in oocysts maintained in potassium dichromate at 25 or 32 degrees C. Complete excystation resulted in the liberation of two sporozoites from the two sporocysts within each oocyst (cryptosporidia have four naked sporozoites within each oocyst). The presence of organelles characteristic of coccidian organisms was confirmed by electron microscopy.<br /><br /><strong>CONCLUSIONS: </strong>We have identified organisms of the genus cyclospora that are remarkably similar to cryptosporidia in their morphologic features and the diarrheal disease that they produce in humans. The complete life cycle and epidemiology of this new protozoan parasite remain to be described."
1234633,Nair and  Krishnamurthi 1993,Cellular distribution of hexa and trivalent chromium in Pseudomonas aeruginosa,"Binding of Cr to P. aeruginosa whole cells increased with an increase in positive charge of the chromium complexes used. Distribution of Cr bound from aqueous solutions of potassium dichromate--a Cr(VI) salt and basic chromium sulphate (BCS)--a Cr(III) salt [used for tanning which has 25% of Cr2O3 on weight basis and is of 33% basicity (one hydroxyl/Cr atom)] was more in soluble fraction (protein and nucleic acids) than in insoluble fraction (lipids, polyphosphates, polysaccharides, lipopolysaccharides and mucopeptides). Electron spin resonance spectrum of the cells exposed to hexavalent chromium revealed the presence of Cr(III) ion demonstrating a reduction of the same by the Pseudomoas. The infrared spectra of chromium exposed cell envelopes support that protein carboxylic sites and proteins are involved in binding Cr(III) and predominantly lipids in Cr(VI). Bound chromium could be removed chemically and the cells could then be reused as a biosorbent.","Cellular distribution of hexa and trivalent chromium in Pseudomonas aeruginosa Abs: Binding of Cr to P. aeruginosa whole cells increased with an increase in positive charge of the chromium complexes used. Distribution of Cr bound from aqueous solutions of potassium dichromate--a Cr(VI) salt and basic chromium sulphate (BCS)--a Cr(III) salt [used for tanning which has 25% of Cr2O3 on weight basis and is of 33% basicity (one hydroxyl/Cr atom)] was more in soluble fraction (protein and nucleic acids) than in insoluble fraction (lipids, polyphosphates, polysaccharides, lipopolysaccharides and mucopeptides). Electron spin resonance spectrum of the cells exposed to hexavalent chromium revealed the presence of Cr(III) ion demonstrating a reduction of the same by the Pseudomoas. The infrared spectra of chromium exposed cell envelopes support that protein carboxylic sites and proteins are involved in binding Cr(III) and predominantly lipids in Cr(VI). Bound chromium could be removed chemically and the cells could then be reused as a biosorbent."
1234631,Subbarao and  Macdonald 1993,Experimental method to correct fluorescence intensities for the inner filter effect,An empirical procedure for the correction of measured fluorescence intensity for the inner filter effect is described. The procedure is more reliable than those described previously as fluorophores with the fluorescence properties of interest are sequestered from the external aqueous phase. The inner filter effect can therefore be assessed in the absence of chemical reaction or Forster energy transfer between the fluorophore and chromophore. A correction curve for the inner filter effect is obtained by measuring the fluorescence intensity of the sequestered fluorophore after adding a chromophore to increase the absorbance of the solution. The procedure was tested with liposomes containing calcein and two commercial polymer bead preparations containing embedded fluorophores. The former have the advantage of a wider choice of fluorophores and the latter of stability and convenience. The inner filter effect was varied using small aliquots of potassium chromate or pyridinium chloride solution. It was shown that the magnitude of the inner filter effect must be experimentally determined for each instrument and whenever the instrumental configuration is altered if an accurate correction for the inner filter effect is to be obtained. The magnitude of the correction depends on the wavelength range and the pathlength but not on slit-width or sample turbidity for the instrument employed for most of the experiments reported here. This empirical procedure makes possible studies of protein fluorescence quenching by agents previously unsuitable because of high absorbances.,Experimental method to correct fluorescence intensities for the inner filter effect Abs: An empirical procedure for the correction of measured fluorescence intensity for the inner filter effect is described. The procedure is more reliable than those described previously as fluorophores with the fluorescence properties of interest are sequestered from the external aqueous phase. The inner filter effect can therefore be assessed in the absence of chemical reaction or Forster energy transfer between the fluorophore and chromophore. A correction curve for the inner filter effect is obtained by measuring the fluorescence intensity of the sequestered fluorophore after adding a chromophore to increase the absorbance of the solution. The procedure was tested with liposomes containing calcein and two commercial polymer bead preparations containing embedded fluorophores. The former have the advantage of a wider choice of fluorophores and the latter of stability and convenience. The inner filter effect was varied using small aliquots of potassium chromate or pyridinium chloride solution. It was shown that the magnitude of the inner filter effect must be experimentally determined for each instrument and whenever the instrumental configuration is altered if an accurate correction for the inner filter effect is to be obtained. The magnitude of the correction depends on the wavelength range and the pathlength but not on slit-width or sample turbidity for the instrument employed for most of the experiments reported here. This empirical procedure makes possible studies of protein fluorescence quenching by agents previously unsuitable because of high absorbances.
1234630,Ikarashi et al. 1993,Influence of irritants on lymph node cell proliferation and the detection of contact sensitivity to metal salts in the murine local lymph node assay,"Dimethyl sulfoxide (DMSO) and sodium lauryl sulfate (SLS) are known to cause irritation of the skin, and to enhance the penetration of chemicals into the epidermis. In the present study, the lymph node cell (LNC) proliferative response following exposure to irritants, such as SLS and DMSO, was examined in the murine local lymph node assay (LLNA). Exposure to DMSO or SLS aqueous solution induced a small increase in lymph node cell proliferation compared with aqueous solution alone. Exposure to SLS in DMSO caused a significant increase in LNC proliferation. Further, the effect of addition of the irritants in a vehicle on the detection of contact sensitivity to metal allergens was examined. Application of potassium dichromate and nickel sulfate in DMSO or SLS aqueous solution caused increases in LNC proliferation. Exposure to metal allergen with SLS in DMSO also induced a significant LNC proliferative response, but did not induce a significant increase in stimulation index (increase in 3H-thymidine incorporation relative to vehicle-treated control group). This was because of increased 3H-thymidine incorporation following exposure to SLS-DMSO in the control group. These results suggest that irritants enhance the LNC proliferative responses to metal allergens. The use of SLS in aqueous solution is effective for the detection of sensitivity to water-soluble allergens, such as metal allergens, in the LLNA, as well as the use of DMSO as an application vehicle.","Influence of irritants on lymph node cell proliferation and the detection of contact sensitivity to metal salts in the murine local lymph node assay Abs: Dimethyl sulfoxide (DMSO) and sodium lauryl sulfate (SLS) are known to cause irritation of the skin, and to enhance the penetration of chemicals into the epidermis. In the present study, the lymph node cell (LNC) proliferative response following exposure to irritants, such as SLS and DMSO, was examined in the murine local lymph node assay (LLNA). Exposure to DMSO or SLS aqueous solution induced a small increase in lymph node cell proliferation compared with aqueous solution alone. Exposure to SLS in DMSO caused a significant increase in LNC proliferation. Further, the effect of addition of the irritants in a vehicle on the detection of contact sensitivity to metal allergens was examined. Application of potassium dichromate and nickel sulfate in DMSO or SLS aqueous solution caused increases in LNC proliferation. Exposure to metal allergen with SLS in DMSO also induced a significant LNC proliferative response, but did not induce a significant increase in stimulation index (increase in 3H-thymidine incorporation relative to vehicle-treated control group). This was because of increased 3H-thymidine incorporation following exposure to SLS-DMSO in the control group. These results suggest that irritants enhance the LNC proliferative responses to metal allergens. The use of SLS in aqueous solution is effective for the detection of sensitivity to water-soluble allergens, such as metal allergens, in the LLNA, as well as the use of DMSO as an application vehicle."
1234629,Vyskocil et al. 1993,Kidney function in male and female rats chronically exposed to potassium dichromate,"Male and female Wistar rats were given 25 mg l-1 chromium (as potassium dichromate) in drinking water for 6 months. Lactate dehydrogenase, lysozyme, total proteins, N-acetyl-beta-D-glucosaminidase, albumin and beta 2-microglobulin (beta 2-m) were measured in 24-h urine after 3 and 6 months of exposure. Body and kidney weight and chromium excretion were also examined. Except for the chromium excretion, no statistically significant changes were observed in the exposed male rats. In female rats there were significant increases in the urinary excretion of albumin after 3 and 6 months of exposure and the urinary excretion of beta 2-m after 3 months of exposure.","Kidney function in male and female rats chronically exposed to potassium dichromate Abs: Male and female Wistar rats were given 25 mg l-1 chromium (as potassium dichromate) in drinking water for 6 months. Lactate dehydrogenase, lysozyme, total proteins, N-acetyl-beta-D-glucosaminidase, albumin and beta 2-microglobulin (beta 2-m) were measured in 24-h urine after 3 and 6 months of exposure. Body and kidney weight and chromium excretion were also examined. Except for the chromium excretion, no statistically significant changes were observed in the exposed male rats. In female rats there were significant increases in the urinary excretion of albumin after 3 and 6 months of exposure and the urinary excretion of beta 2-m after 3 months of exposure."
1234628,Roche and  Bogé 1993,"Effects of Cu, Zn and Cr salts on antioxidant enzyme activities In vitro of red blood cells of a marine fish Dicentrarchus labrax","Effects of xenobiotics (potassium dichromate, copper sulphate and zinc chloride) in vitro on antioxidant enzyme activities and lipid peroxidation in sea bass erythrocytes were investigated. Total cell haemolysis was observed after 24 hr of exposure to 2 mm dichromate at 20 degrees C, 0.1 mm CuSO(4) and 1 mm ZnCl(2). 24 hr exposure to non-haemolytic concentrations of CuSO(4) and ZnCl(2) led to a concentration-related decrease in glutathione peroxidase activity. With dichromate, this activity was increased at the lowest concentrations (1-100 mum) and was decreased for the highest (0.5 and 1 mm). Dual effects were also found on dichromate-treated cells for manganese-dependent superoxide dismutase activity, whereas Zn(2+) had only inhibitory effects. Total superoxide dismutase activity was depressed by CuSO(4) and ZnCl(2); this effect was concentration dependent. With regard to catalase activity, ZnCl(2) and K(2)Cr(2)O(7) were found to be activators, whereas CuSO(4) was an inhibitor. Study of the effects of metals on lipid peroxidation was based on the release of TBA-reactive substances in the surrounding medium; 24 hr exposure to 1 mm dichromate, 10 mum CuSO(4) and, in particular, 100 mum ZnCl(2), increased the amount of this lipid peroxidation indicator. This work suggests that the defence system of sea bass red blood cells against active oxygen species can be compromised by metal ions, this imbalance being able to cause increased membrane lipid peroxidation. This study has demonstrated that seawater fish erythrocytes are a valid cell model for study of the effects in vitro of xenobiotics on antioxidant mechanisms.","Effects of Cu, Zn and Cr salts on antioxidant enzyme activities In vitro of red blood cells of a marine fish Dicentrarchus labrax Abs: Effects of xenobiotics (potassium dichromate, copper sulphate and zinc chloride) in vitro on antioxidant enzyme activities and lipid peroxidation in sea bass erythrocytes were investigated. Total cell haemolysis was observed after 24 hr of exposure to 2 mm dichromate at 20 degrees C, 0.1 mm CuSO(4) and 1 mm ZnCl(2). 24 hr exposure to non-haemolytic concentrations of CuSO(4) and ZnCl(2) led to a concentration-related decrease in glutathione peroxidase activity. With dichromate, this activity was increased at the lowest concentrations (1-100 mum) and was decreased for the highest (0.5 and 1 mm). Dual effects were also found on dichromate-treated cells for manganese-dependent superoxide dismutase activity, whereas Zn(2+) had only inhibitory effects. Total superoxide dismutase activity was depressed by CuSO(4) and ZnCl(2); this effect was concentration dependent. With regard to catalase activity, ZnCl(2) and K(2)Cr(2)O(7) were found to be activators, whereas CuSO(4) was an inhibitor. Study of the effects of metals on lipid peroxidation was based on the release of TBA-reactive substances in the surrounding medium; 24 hr exposure to 1 mm dichromate, 10 mum CuSO(4) and, in particular, 100 mum ZnCl(2), increased the amount of this lipid peroxidation indicator. This work suggests that the defence system of sea bass red blood cells against active oxygen species can be compromised by metal ions, this imbalance being able to cause increased membrane lipid peroxidation. This study has demonstrated that seawater fish erythrocytes are a valid cell model for study of the effects in vitro of xenobiotics on antioxidant mechanisms."
1234627,Helmbold et al. 1993,Induction of type IV hypersensitivity to contact allergens in guinea pigs by in vitro haptenized allogenic peritoneal exudate cells,"The induction of type IV hypersensitivity to contact allergens in guinea pigs has been studied by using allogenic peritoneal exudate cells (&gt; 90% macrophages), which had been incubated primarily in vitro with dinitrochlorobenzene, formaldehyde, potassium dichromate, nickel II sulphate or para-aminobenzoic acid. In these guinea pig sensitization experiments Freund's complete adjuvant was used. In all haptens investigated the sensitization rates of the presented method were parallel to the known contact allergenicity in humans and, apart from the potassium dichromate results, comparable with those of the guinea pig maximization test. Because of its alternative immunization procedure, in which only few or no allergen molecules escape the effective presentation pathway, the authors conclude that this method could be developed into a predictive test assay for the evaluation of the contact allergenicity of water-soluble substances.","Induction of type IV hypersensitivity to contact allergens in guinea pigs by in vitro haptenized allogenic peritoneal exudate cells Abs: The induction of type IV hypersensitivity to contact allergens in guinea pigs has been studied by using allogenic peritoneal exudate cells (&gt; 90% macrophages), which had been incubated primarily in vitro with dinitrochlorobenzene, formaldehyde, potassium dichromate, nickel II sulphate or para-aminobenzoic acid. In these guinea pig sensitization experiments Freund's complete adjuvant was used. In all haptens investigated the sensitization rates of the presented method were parallel to the known contact allergenicity in humans and, apart from the potassium dichromate results, comparable with those of the guinea pig maximization test. Because of its alternative immunization procedure, in which only few or no allergen molecules escape the effective presentation pathway, the authors conclude that this method could be developed into a predictive test assay for the evaluation of the contact allergenicity of water-soluble substances."
1234626,Shiau and  Chen 1993,Carbohydrate utilization by tilapia (Oreochromis niloticus x O. aureus) as influenced by different chromium sources,"An experiment was conducted to study the influence of three different forms of chromium (CrCl3.6H2O, Na2CrO4.4H2O and Cr2O3) on the utilization of two carbohydrates (glucose and cornstarch) by juvenile hybrid tilapia (Oreochromis niloticus x O. aureus). Average initial body weight of the fish was 1.13 +/- 0.02 g. Fish were fed 5% body wt/d. Significantly (P &lt; 0.05) greater body weight gain, food intake, protein retention, energy retention and body lipid concentration were observed in fish fed the starch diet than in those fed the glucose diet. Fish fed the glucose diet supplemented with any type of chromium had significantly greater weight gain than those fed the glucose diet without chromium supplementation. Fish fed the glucose diet supplemented with Cr2O3 had greater weight gain, food intake, protein retention, energy retention and body lipid concentration than those fed the unsupplemented glucose diet or the glucose diet supplemented with CrCl3.6H2O or Na2CrO4.4H2O. Delayed plasma glucose peak time was observed in tilapia fed the glucose diet supplemented with any type of chromium. Chromium supplementation generally lowered the glucose-6-phosphatase activity in tilapia. Phosphofructokinase activity was significantly higher in fish fed the glucose diet supplemented with Cr2O3 than in the other glucose-fed groups. These data suggest that chromium supplementation improved glucose utilization by tilapia and that Cr2O3 supplementation was markedly more effective than other chromium forms.","Carbohydrate utilization by tilapia (Oreochromis niloticus x O. aureus) as influenced by different chromium sources Abs: An experiment was conducted to study the influence of three different forms of chromium (CrCl3.6H2O, Na2CrO4.4H2O and Cr2O3) on the utilization of two carbohydrates (glucose and cornstarch) by juvenile hybrid tilapia (Oreochromis niloticus x O. aureus). Average initial body weight of the fish was 1.13 +/- 0.02 g. Fish were fed 5% body wt/d. Significantly (P &lt; 0.05) greater body weight gain, food intake, protein retention, energy retention and body lipid concentration were observed in fish fed the starch diet than in those fed the glucose diet. Fish fed the glucose diet supplemented with any type of chromium had significantly greater weight gain than those fed the glucose diet without chromium supplementation. Fish fed the glucose diet supplemented with Cr2O3 had greater weight gain, food intake, protein retention, energy retention and body lipid concentration than those fed the unsupplemented glucose diet or the glucose diet supplemented with CrCl3.6H2O or Na2CrO4.4H2O. Delayed plasma glucose peak time was observed in tilapia fed the glucose diet supplemented with any type of chromium. Chromium supplementation generally lowered the glucose-6-phosphatase activity in tilapia. Phosphofructokinase activity was significantly higher in fish fed the glucose diet supplemented with Cr2O3 than in the other glucose-fed groups. These data suggest that chromium supplementation improved glucose utilization by tilapia and that Cr2O3 supplementation was markedly more effective than other chromium forms."
1234624,Ziegler and  Ziegler 1994,Experimentally induced malignant lymphoma due to chronic antigen stimulation,"Animal experiments were started in 1988 with the aim of inducing malignant lymphomas. 52 guinea pigs were exposed to potassium dichromate using the TINA test (plus 39 control animals). Following the sensitization procedure, the test animals and 15 control guinea pigs were exposed daily (5 x a week) epicutaneously to the antigen up to the present time. Currently, 30 exposed and 17 control animals are still in the experiment. In 3 out of 17 post-mortem examinations, histologically evident lymphomas were found. In the control animals, no tumor has been seen. The experiments support lymphoma causation by chronic antigen stimulation. The experiments are continuing.","Experimentally induced malignant lymphoma due to chronic antigen stimulation Abs: Animal experiments were started in 1988 with the aim of inducing malignant lymphomas. 52 guinea pigs were exposed to potassium dichromate using the TINA test (plus 39 control animals). Following the sensitization procedure, the test animals and 15 control guinea pigs were exposed daily (5 x a week) epicutaneously to the antigen up to the present time. Currently, 30 exposed and 17 control animals are still in the experiment. In 3 out of 17 post-mortem examinations, histologically evident lymphomas were found. In the control animals, no tumor has been seen. The experiments support lymphoma causation by chronic antigen stimulation. The experiments are continuing."
1234623,Vilaplana et al. 1994,Contact dermatitis and adverse oral mucous membrane reactions related to the use of dental prostheses,"The latest trends in the use and composition of dental prostheses have been reviewed, and 66 patients referred by dermatologists and odontologists patch tested. The allergen series used were: TRUE Test standard series; Chemotechnique dental screening series; specially prepared metals series. The allergens found to be positive, in order of frequency, were: nickel, cobalt, potassium dichromate, rhodium, palladium, mercury, beryllium, methyl methacrylate, copper and zinc.","Contact dermatitis and adverse oral mucous membrane reactions related to the use of dental prostheses Abs: The latest trends in the use and composition of dental prostheses have been reviewed, and 66 patients referred by dermatologists and odontologists patch tested. The allergen series used were: TRUE Test standard series; Chemotechnique dental screening series; specially prepared metals series. The allergens found to be positive, in order of frequency, were: nickel, cobalt, potassium dichromate, rhodium, palladium, mercury, beryllium, methyl methacrylate, copper and zinc."
1234621,Wang et al. 1994,Patch testing with the European standard series in Shanghai,,Patch testing with the European standard series in Shanghai Abs: 
1234620,Stearns and  Wetterhahn 1994,"Reaction of chromium(VI) with ascorbate produces chromium(V), chromium(IV), and carbon-based radicals","Reaction of potassium dichromate with sodium ascorbate was studied by EPR spectroscopy at room temperature, in 0.10 M N-[2-hydroxyethyl]piperazine-N'-[2-ethanesulfonic acid] (HEPES), phosphate, cacodylate, and tris(hydroxymethyl)aminomethane hydrochloride (Tris.HCl) buffers at pH 7.0, in the presence of 0.10 M spin trap [5,5-dimethyl-1-pyrroline 1-oxide or 2-methyl-N-(4-pyridinylmethylene)-2-propanamine N,N'-dioxide]. Chromium(V), ascorbate radical, CO2-, and other carbon-based spin trap-radical adducts were observed. Chromium(V), CO2-, and the carbon-based radicals were observed at low ratios of ascorbate to chromium, and ascorbate radical was observed at high ratios of ascorbate to chromium. The presence of Cr(IV) was detected indirectly by reaction with Mn(II) and a subsequent decrease in the Mn(II) EPR signal. More Cr(IV) was found for the higher reaction ratios of ascorbate to Cr(VI). The only buffer effect observed was a relative decrease of the Cr(V) signal in Tris.HCl vs HEPES, phosphate, and cacodylate buffers, no change in the radical adducts was observed. There was no evidence for reactive oxygen species an intermediates in this reaction. Addition of the singlet oxygen trap 2,2,6,6-tetramethyl-4-piperidone hydrochloride showed no 2,2,6,6-tetramethyl-1-piperidinyloxy radical formation. The Cr(V) species did not react with dioxygen, and dioxygen did not affect the formation of carbon-based radicals. A mechanism consistent with these observations is discussed.","Reaction of chromium(VI) with ascorbate produces chromium(V), chromium(IV), and carbon-based radicals Abs: Reaction of potassium dichromate with sodium ascorbate was studied by EPR spectroscopy at room temperature, in 0.10 M N-[2-hydroxyethyl]piperazine-N'-[2-ethanesulfonic acid] (HEPES), phosphate, cacodylate, and tris(hydroxymethyl)aminomethane hydrochloride (Tris.HCl) buffers at pH 7.0, in the presence of 0.10 M spin trap [5,5-dimethyl-1-pyrroline 1-oxide or 2-methyl-N-(4-pyridinylmethylene)-2-propanamine N,N'-dioxide]. Chromium(V), ascorbate radical, CO2-, and other carbon-based spin trap-radical adducts were observed. Chromium(V), CO2-, and the carbon-based radicals were observed at low ratios of ascorbate to chromium, and ascorbate radical was observed at high ratios of ascorbate to chromium. The presence of Cr(IV) was detected indirectly by reaction with Mn(II) and a subsequent decrease in the Mn(II) EPR signal. More Cr(IV) was found for the higher reaction ratios of ascorbate to Cr(VI). The only buffer effect observed was a relative decrease of the Cr(V) signal in Tris.HCl vs HEPES, phosphate, and cacodylate buffers, no change in the radical adducts was observed. There was no evidence for reactive oxygen species an intermediates in this reaction. Addition of the singlet oxygen trap 2,2,6,6-tetramethyl-4-piperidone hydrochloride showed no 2,2,6,6-tetramethyl-1-piperidinyloxy radical formation. The Cr(V) species did not react with dioxygen, and dioxygen did not affect the formation of carbon-based radicals. A mechanism consistent with these observations is discussed."
1234617,Veien et al. 1994,Stomatitis or systemically-induced contact dermatitis from metal wire in orthodontic materials,"5 patients with dermatitis or stomatitis related to the use of orthodontic appliances are described. All the patients were patch tested with the European standard series. One had a ++ reaction to potassium dichromate, one a ++ reaction to nickel, and the remaining 3 no positive patch tests. 3 of the patients had recurrent vesicular hand eczema, which flared after oral challenge with 1 of the metals used in their orthodontic appliances. 2 of these 3 patients had negative patch tests. The dermatitis of 4 of the 5 patients cleared completely upon the removal of their metal orthodontic appliances or their replacement with appliances made of acrylics.","Stomatitis or systemically-induced contact dermatitis from metal wire in orthodontic materials Abs: 5 patients with dermatitis or stomatitis related to the use of orthodontic appliances are described. All the patients were patch tested with the European standard series. One had a ++ reaction to potassium dichromate, one a ++ reaction to nickel, and the remaining 3 no positive patch tests. 3 of the patients had recurrent vesicular hand eczema, which flared after oral challenge with 1 of the metals used in their orthodontic appliances. 2 of these 3 patients had negative patch tests. The dermatitis of 4 of the 5 patients cleared completely upon the removal of their metal orthodontic appliances or their replacement with appliances made of acrylics."
1234616,Giglio et al. 1994,Erythropoietin production in hypoxemic rats with selective necrotic damage of the different regions of the proximal tubules,,Erythropoietin production in hypoxemic rats with selective necrotic damage of the different regions of the proximal tubules Abs: 
1234615,Seiken et al. 1994,Modulation of renal EGF in dichromate-induced acute renal failure treated with thyroid hormone,"Administration of either thyroid hormone or epidermal growth factor (EGF) ameliorates injury in a variety of experimental acute renal failure (ARF) models. Since thyroid hormone augments EGF release and EGF receptor expression, a hypothesis suggesting that the mechanism of thyroid action is via EGF appears attractive. The present study is an attempt to evaluate the role of EGF in thyroid mediated protection from ARF induced in rats by dichromate. Renal parenchymal levels of acid extractable endogenous EGF were measured by RIA in dichromate exposed, otherwise untreated animals and in those receiving dichromate followed by thyroid. In the untreated case serum creatinine peaked at 2.5 mg % on the third day following dichromate exposure. Endogenous levels of EGF closely paralleled serum creatinine with a six-fold increase observed at peak injury. The source of EGF increase appeared to be a membrane bound precursor as soluble levels of EGF rose in injured kidneys at the expense of Triton-X-100 extractable, immunoreactive material that upon treatment with trypsin yielded additional EGF. T3 administered one hour following dichromate resulted in significant functional protection (peak injury serum creatinines 2.63 +/- 0.76 control vs. 0.98 +/- 0.14 with T3) as well as an approximate doubling in renal EGF levels at 24, 48 and 72 hours (4.7 +/- 0.3 vs. 9.7 +/- 0.8 at 24 hr, 33.5 +/- 6.5 vs. 63.2 +/- 20.0 at 48 hr, and 23.1 +/- 10.0 vs. 44.1 +/- 8.7 ng/g wet weight at 72 hr). There was no beneficial effect of exogenous EGF on renal function either when given in conjunction with T3 or when used alone.(ABSTRACT TRUNCATED AT 250 WORDS)","Modulation of renal EGF in dichromate-induced acute renal failure treated with thyroid hormone Abs: Administration of either thyroid hormone or epidermal growth factor (EGF) ameliorates injury in a variety of experimental acute renal failure (ARF) models. Since thyroid hormone augments EGF release and EGF receptor expression, a hypothesis suggesting that the mechanism of thyroid action is via EGF appears attractive. The present study is an attempt to evaluate the role of EGF in thyroid mediated protection from ARF induced in rats by dichromate. Renal parenchymal levels of acid extractable endogenous EGF were measured by RIA in dichromate exposed, otherwise untreated animals and in those receiving dichromate followed by thyroid. In the untreated case serum creatinine peaked at 2.5 mg % on the third day following dichromate exposure. Endogenous levels of EGF closely paralleled serum creatinine with a six-fold increase observed at peak injury. The source of EGF increase appeared to be a membrane bound precursor as soluble levels of EGF rose in injured kidneys at the expense of Triton-X-100 extractable, immunoreactive material that upon treatment with trypsin yielded additional EGF. T3 administered one hour following dichromate resulted in significant functional protection (peak injury serum creatinines 2.63 +/- 0.76 control vs. 0.98 +/- 0.14 with T3) as well as an approximate doubling in renal EGF levels at 24, 48 and 72 hours (4.7 +/- 0.3 vs. 9.7 +/- 0.8 at 24 hr, 33.5 +/- 6.5 vs. 63.2 +/- 20.0 at 48 hr, and 23.1 +/- 10.0 vs. 44.1 +/- 8.7 ng/g wet weight at 72 hr). There was no beneficial effect of exogenous EGF on renal function either when given in conjunction with T3 or when used alone.(ABSTRACT TRUNCATED AT 250 WORDS)"
1234614,Krassoi and  Julli 1994,Chemical batch as a factor affecting the acute toxicity of the reference toxicant potassium dichromate to the cladoceran Moina australiensis (Sars),BIOSIS COPYRIGHT: BIOL ABS. RRM RESEARCH ARTICLE MOINA-AUSTRALIENSIS POTENTIAL WATER POLLUTANT WATER EQUALITY VARIABLES COMMERCIAL SOURCE VARIATION BASELINE PHYSIOLOGY ECOTOXICOLOGY MANUFACTURER VARIATION AJAX BDH MALLINCKRODT AUSTRALIA,Chemical batch as a factor affecting the acute toxicity of the reference toxicant potassium dichromate to the cladoceran Moina australiensis (Sars) Abs: BIOSIS COPYRIGHT: BIOL ABS. RRM RESEARCH ARTICLE MOINA-AUSTRALIENSIS POTENTIAL WATER POLLUTANT WATER EQUALITY VARIABLES COMMERCIAL SOURCE VARIATION BASELINE PHYSIOLOGY ECOTOXICOLOGY MANUFACTURER VARIATION AJAX BDH MALLINCKRODT AUSTRALIA
1234613,Scholes et al. 1994,Skin metabolism of contact allergens,"Skin possesses metabolic capacity which may be significant for chemicals with direct skin effects. The conversion of some chemical contact allergens from an inactive to an active hapten has also been described. Eugenol and isoeugenol are contact allergens that fit this description, but despite close chemical similarity, they are not cross-reactive and this has led to the hypothesis that they may be activated by different mechanisms. There is evidence that eugenol follows a phenolic radical mechanism, while isoeugenol undergoes demethylation followed by oxidation to the orthoquinone. Since these reactions may be cytochrome P-450 mediated (the former being cytochrome P4501A driven) we investigated how modulation of this system affects skin sensitization to eugenol and isoeugenol. Using the local lymph node assay, which measures lymphocyte proliferation in draining lymph nodes, the effect of clotrimazole, an inhibitor of epidermal cytochrome P4501A, was assessed. Clotrimazole enhanced the response to eugenol and potassium dichromate (an irrelevant contact allergen) approximately two-fold and isoeugenol five-fold. It was anticipated that clotrimazole would have little effect on isoeugenol sensitization, but that through inhibition of cytochrome P4501A, eugenol sensitization would be reduced. However, the present data suggest that the presence of P4501A in skin may result in the metabolism of these chemicals to relatively harmless moieties.","Skin metabolism of contact allergens Abs: Skin possesses metabolic capacity which may be significant for chemicals with direct skin effects. The conversion of some chemical contact allergens from an inactive to an active hapten has also been described. Eugenol and isoeugenol are contact allergens that fit this description, but despite close chemical similarity, they are not cross-reactive and this has led to the hypothesis that they may be activated by different mechanisms. There is evidence that eugenol follows a phenolic radical mechanism, while isoeugenol undergoes demethylation followed by oxidation to the orthoquinone. Since these reactions may be cytochrome P-450 mediated (the former being cytochrome P4501A driven) we investigated how modulation of this system affects skin sensitization to eugenol and isoeugenol. Using the local lymph node assay, which measures lymphocyte proliferation in draining lymph nodes, the effect of clotrimazole, an inhibitor of epidermal cytochrome P4501A, was assessed. Clotrimazole enhanced the response to eugenol and potassium dichromate (an irrelevant contact allergen) approximately two-fold and isoeugenol five-fold. It was anticipated that clotrimazole would have little effect on isoeugenol sensitization, but that through inhibition of cytochrome P4501A, eugenol sensitization would be reduced. However, the present data suggest that the presence of P4501A in skin may result in the metabolism of these chemicals to relatively harmless moieties."
1234612,Veien et al. 1994,Chromate-allergic patients challenged orally with potassium dichromate,"30 patients who had positive patch tests to potassium dichromate participated in a placebo-controlled oral challenge with 2.5 mg chromium given as potassium dichromate. 17 reacted to chromate but not to the placebo, 2 reacted to both chromate and the placebo, and 4 reacted to the placebo but not chromate. 7 patients had no reaction. A specific reaction to chromate was most common among patients with dermatitis of the hands and/or feet.","Chromate-allergic patients challenged orally with potassium dichromate Abs: 30 patients who had positive patch tests to potassium dichromate participated in a placebo-controlled oral challenge with 2.5 mg chromium given as potassium dichromate. 17 reacted to chromate but not to the placebo, 2 reacted to both chromate and the placebo, and 4 reacted to the placebo but not chromate. 7 patients had no reaction. A specific reaction to chromate was most common among patients with dermatitis of the hands and/or feet."
1234609,Rudhart and  Hirth 1994,Use of an absorbent in laser lithotripsy with dye lasers: in vitro study of fragmentation efficiency and jet formation,"Among other things, the fragmentation efficiency of laser lithotripsy using a dye laser depends upon the physical properties of the surface of the calculus, especially optical absorption. In this in vitro study we were able to increase the fragmentation efficiency on white, nonabsorbing calculi by introducing an absorbing liquid between the distal end of the fiber and the stone surface. This absorbing liquid (in our case potassium dichromate) provides a reliable plasma ignition and thus makes the fragmentation independent of the properties of the stone surface. Furthermore, we examined and documented the existence of liquid jets that were produced by the collapse of a cavitation bubble near a stone. We observed considerable fragmentation effects on artificial stones that were, however, inferior to those achieved with the fiber in contact with the stone. This work suggests that the effects of a liquid jet should be taken into consideration when using a holmium:YAG laser for lithotripsy.","Use of an absorbent in laser lithotripsy with dye lasers: in vitro study of fragmentation efficiency and jet formation Abs: Among other things, the fragmentation efficiency of laser lithotripsy using a dye laser depends upon the physical properties of the surface of the calculus, especially optical absorption. In this in vitro study we were able to increase the fragmentation efficiency on white, nonabsorbing calculi by introducing an absorbing liquid between the distal end of the fiber and the stone surface. This absorbing liquid (in our case potassium dichromate) provides a reliable plasma ignition and thus makes the fragmentation independent of the properties of the stone surface. Furthermore, we examined and documented the existence of liquid jets that were produced by the collapse of a cavitation bubble near a stone. We observed considerable fragmentation effects on artificial stones that were, however, inferior to those achieved with the fiber in contact with the stone. This work suggests that the effects of a liquid jet should be taken into consideration when using a holmium:YAG laser for lithotripsy."
1234607,Kadiiska et al. 1994,In vivo free radical generation by chromium(VI): an electron spin resonance spin-trapping investigation,"Although studies in chemical and biological systems have demonstrated that free radical formation is mediated by Cr(VI), no ESR evidence for the generation of free radicals in vivo has been reported. We have employed an ESR spin-trapping technique to detect an adduct of the spin trap alpha-(4-pyridyl 1-oxide)-N-tert-butylnitrone (4-POBN) in the bile of animals given an intragastric dose of potassium dichromate. In this study, we provide evidence for in vivo radical generation resulting from Cr(VI)-poisoned rats. Upon the administration of Cr(VI) and 4-POBN, the ESR spectrum of the radical adducts present in the bile exhibited hyperfine coupling constants aN = 15.71 G and a beta H = 2.90 G. We suggest that the radical responsible for this 4-POBN adduct is carbon-centered and derived from endogenous lipids. The radical adducts detected in the bile from Cr(VI)-treated rats are proposed to be formed and trapped in the liver and excreted into bile. This is the first report of electron spin resonance evidence for the in vivo generation of free radicals by Cr(VI).","In vivo free radical generation by chromium(VI): an electron spin resonance spin-trapping investigation Abs: Although studies in chemical and biological systems have demonstrated that free radical formation is mediated by Cr(VI), no ESR evidence for the generation of free radicals in vivo has been reported. We have employed an ESR spin-trapping technique to detect an adduct of the spin trap alpha-(4-pyridyl 1-oxide)-N-tert-butylnitrone (4-POBN) in the bile of animals given an intragastric dose of potassium dichromate. In this study, we provide evidence for in vivo radical generation resulting from Cr(VI)-poisoned rats. Upon the administration of Cr(VI) and 4-POBN, the ESR spectrum of the radical adducts present in the bile exhibited hyperfine coupling constants aN = 15.71 G and a beta H = 2.90 G. We suggest that the radical responsible for this 4-POBN adduct is carbon-centered and derived from endogenous lipids. The radical adducts detected in the bile from Cr(VI)-treated rats are proposed to be formed and trapped in the liver and excreted into bile. This is the first report of electron spin resonance evidence for the in vivo generation of free radicals by Cr(VI)."
1234606,Ramana and  Sastry 1994,Chromium toxicity in Neurospora crassa,"A comparative study has been made on the mechanisms of toxicities of trivalent and hexavalent forms of chromium in Neurospora crassa. Of the two forms, Cr6+ is more toxic than Cr3+. The toxicity of Cr3+ was found to be due to its specific antagonism with iron uptake. Fe3+ was found to be very effective in reversing the toxicity of Cr3+ by concomitantly suppressing its uptake. That the Cr3+ toxicity caused a conditional intracellular iron deficiency was indicated by the decrease in the activities of catalase and uricase and a progressive increase in the excretion of iron binding compound into the medium. The toxicity of Cr6+ (as Cr2O7(2-)) was found to be due to its specific antagonism of sulfate uptake. Methionine was found to be more effective in reversing dichromate toxicity than sulfate, probably by repressing the synthesis of sulfate permeases responsible for dichromate (Cr6+) uptake. Maximal uptake of Cr6+ was nearly tenfold lower and Vmax much higher than that of Cr3+. Evidence has been adduced to show that Cr6+ and Cr3+ were toxic by themselves and that interconversion between the tri- and hexavalent forms of chromium did not occur to any detectable extent.","Chromium toxicity in Neurospora crassa Abs: A comparative study has been made on the mechanisms of toxicities of trivalent and hexavalent forms of chromium in Neurospora crassa. Of the two forms, Cr6+ is more toxic than Cr3+. The toxicity of Cr3+ was found to be due to its specific antagonism with iron uptake. Fe3+ was found to be very effective in reversing the toxicity of Cr3+ by concomitantly suppressing its uptake. That the Cr3+ toxicity caused a conditional intracellular iron deficiency was indicated by the decrease in the activities of catalase and uricase and a progressive increase in the excretion of iron binding compound into the medium. The toxicity of Cr6+ (as Cr2O7(2-)) was found to be due to its specific antagonism of sulfate uptake. Methionine was found to be more effective in reversing dichromate toxicity than sulfate, probably by repressing the synthesis of sulfate permeases responsible for dichromate (Cr6+) uptake. Maximal uptake of Cr6+ was nearly tenfold lower and Vmax much higher than that of Cr3+. Evidence has been adduced to show that Cr6+ and Cr3+ were toxic by themselves and that interconversion between the tri- and hexavalent forms of chromium did not occur to any detectable extent."
1234605,Dotterud and  Falk 1994,Metal allergy in north Norwegian schoolchildren and its relationship with ear piercing and atopy,"In 424 schoolchildren (223 boys and 201 girls) aged 7-12 years undergoing routine patch tests, 21.0% (89 children), 38.8% (78/201) of girls and 4.9% (11/223) of boys, had had their ears pierced. 18.6% (79 children, 55 girls and 24 boys) gave a history of cutaneous reactions to metallic jewelry, and in 17.2% (73 children, 49 girls and 24 boys), sensitivity to one or more metals was confirmed. Metal allergy was confirmed by patch testing in only 34.2% of the children with a history of metal dermatitis, and 13.3% of those without a history of metal reactions had, in fact, positive patch tests to 1 or more metals. The low sensitivity (37.0%) and low positive predictive value (34.2%), together with high specificity (85.2%) and high negative predictive value (86.7%), seem to justify dermatological examination of individuals with a positive symptom-based diagnosis only. Nickel sensitivity was found in 14.9% (63 children, 44 girls and 19 boys). There is clearly a relationship between ear piercing and induction of nickel allergy in girls, as nickel sensitivity in girls with pierced ears was 2x (30.8%) that found in those without (16.3%) pierced ears. In boys, nickel sensitivity was much less frequent and few cases were related to ear piercing. Atopy appeared to influence the propensity for developing metal sensitivity in girls, as atopic girls showed positive metal tests 2x as frequently (30.8%) as non-atopic (17.0%).(ABSTRACT TRUNCATED AT 250 WORDS)","Metal allergy in north Norwegian schoolchildren and its relationship with ear piercing and atopy Abs: In 424 schoolchildren (223 boys and 201 girls) aged 7-12 years undergoing routine patch tests, 21.0% (89 children), 38.8% (78/201) of girls and 4.9% (11/223) of boys, had had their ears pierced. 18.6% (79 children, 55 girls and 24 boys) gave a history of cutaneous reactions to metallic jewelry, and in 17.2% (73 children, 49 girls and 24 boys), sensitivity to one or more metals was confirmed. Metal allergy was confirmed by patch testing in only 34.2% of the children with a history of metal dermatitis, and 13.3% of those without a history of metal reactions had, in fact, positive patch tests to 1 or more metals. The low sensitivity (37.0%) and low positive predictive value (34.2%), together with high specificity (85.2%) and high negative predictive value (86.7%), seem to justify dermatological examination of individuals with a positive symptom-based diagnosis only. Nickel sensitivity was found in 14.9% (63 children, 44 girls and 19 boys). There is clearly a relationship between ear piercing and induction of nickel allergy in girls, as nickel sensitivity in girls with pierced ears was 2x (30.8%) that found in those without (16.3%) pierced ears. In boys, nickel sensitivity was much less frequent and few cases were related to ear piercing. Atopy appeared to influence the propensity for developing metal sensitivity in girls, as atopic girls showed positive metal tests 2x as frequently (30.8%) as non-atopic (17.0%).(ABSTRACT TRUNCATED AT 250 WORDS)"
1234604,Caraffini et al. 1994,"Tylosin, an airborne contact allergen in veterinarians","A case study of a 31 year old man who had worked on a pig farm for 7 years and who recently developed erythema and itchy papules on the forehead, upper cheeks, and forearms was described. The lesions developed one day after administering the antibiotic Vetil. The antibiotic contains tylosin (1401690) in propylene-glycol (57556) and benzyl-alcohol (100516). The patient was patch tested and was positive to potassium-dichromate (7778509), undiluted Vetil solution, Vetil solution diluted 50%, and tylosin-tartrate (1405545). Once exposure to tylosin was stopped, the dermatitis cleared and there was no relapse since tylosin was replaced with aminoglycosides. The authors proposed that the location of the allergic dermatitis on the face of the patient suggested that there was airborne contact, possibly when the animals moved or when mixing tylosin powder with the feed.","Tylosin, an airborne contact allergen in veterinarians Abs: A case study of a 31 year old man who had worked on a pig farm for 7 years and who recently developed erythema and itchy papules on the forehead, upper cheeks, and forearms was described. The lesions developed one day after administering the antibiotic Vetil. The antibiotic contains tylosin (1401690) in propylene-glycol (57556) and benzyl-alcohol (100516). The patient was patch tested and was positive to potassium-dichromate (7778509), undiluted Vetil solution, Vetil solution diluted 50%, and tylosin-tartrate (1405545). Once exposure to tylosin was stopped, the dermatitis cleared and there was no relapse since tylosin was replaced with aminoglycosides. The authors proposed that the location of the allergic dermatitis on the face of the patient suggested that there was airborne contact, possibly when the animals moved or when mixing tylosin powder with the feed."
1234600,Vaca Pacheco et al. 1995,Inorganic-ion resistance by bacteria isolated from a Mexico City freeway,"Bacteria were isolated from soil samples, containing high exchangeable lead concentrations, obtained from a busy freeway in the México City metropolitan area. Forty-five selected strains (86.7% Gram-positive) had a single MIC distribution pattern for lead (800-1600 micrograms/ml lead nitrate) and were considered lead-resistant. The isolates showed variable levels of resistance to arsenate (86.7%), chromate (66.7%), cadmium (57.6%), and mercury (31.1%) ions. Multiple inorganic-ion resistance was shown by all strains.","Inorganic-ion resistance by bacteria isolated from a Mexico City freeway Abs: Bacteria were isolated from soil samples, containing high exchangeable lead concentrations, obtained from a busy freeway in the México City metropolitan area. Forty-five selected strains (86.7% Gram-positive) had a single MIC distribution pattern for lead (800-1600 micrograms/ml lead nitrate) and were considered lead-resistant. The isolates showed variable levels of resistance to arsenate (86.7%), chromate (66.7%), cadmium (57.6%), and mercury (31.1%) ions. Multiple inorganic-ion resistance was shown by all strains."
1234599,Boscolo et al. 1995,Lymphocyte subpopulations of workers in a plant producing plastic materials (preliminary study),"Lymphocyte subpopulations were studied in 31 men working in a plant producing plastic materials in relation with control groups of similar age and smoking habit. 8 workers (group A) were exposed to solvents (mainly methylethylketone and dimethylformamide), 8 men (group B) to dust containing particles of calcium carbonate, polyvinylchloride, phtalates, unsaturated oils, paraffin wax, iron oxides, titanium bioxides, barium, zinc and lead and 15 men (group C), working in the same department as group B, were studied after a period of 16 months during which lead chromate was employed in the preparation of colors. The lymphocyte subpopulations were normal in group A, while in B there was a significant increase of HLA-DR + cells (monocytes, B and activated T lymphocytes). In group C, T helper/inducer lymphocytes (mainly CD4(+)-CD45RO- &quot;virgin&quot; lymphocytes), CD19+ B lymphocytes, CD3-HLADR+ and CD3-CD25+ (activated B lymphocytes and monocytes) were significantly reduced without changes of serum IgM, IgG and IgA. Highly significant correlation was found between B lymphocytes (reduced in the workers about 40%) and CD4(+)-CD45R0+ &quot;memory&quot; lymphocytes (reduced about 20%). Moreover, blood lead (correlated with urinary chromium) showed a highly significant negative correlation with the B lymphocytes. This study demonstrates that combined exposure to toxic agents produces specific modifications in the lymphocyte subsets without changes in immunoglobulins and confirms the results of previous researches showing that the exposure to lead or chromate induces reduction of lymphocytes in the peripheral blood.","Lymphocyte subpopulations of workers in a plant producing plastic materials (preliminary study) Abs: Lymphocyte subpopulations were studied in 31 men working in a plant producing plastic materials in relation with control groups of similar age and smoking habit. 8 workers (group A) were exposed to solvents (mainly methylethylketone and dimethylformamide), 8 men (group B) to dust containing particles of calcium carbonate, polyvinylchloride, phtalates, unsaturated oils, paraffin wax, iron oxides, titanium bioxides, barium, zinc and lead and 15 men (group C), working in the same department as group B, were studied after a period of 16 months during which lead chromate was employed in the preparation of colors. The lymphocyte subpopulations were normal in group A, while in B there was a significant increase of HLA-DR + cells (monocytes, B and activated T lymphocytes). In group C, T helper/inducer lymphocytes (mainly CD4(+)-CD45RO- &quot;virgin&quot; lymphocytes), CD19+ B lymphocytes, CD3-HLADR+ and CD3-CD25+ (activated B lymphocytes and monocytes) were significantly reduced without changes of serum IgM, IgG and IgA. Highly significant correlation was found between B lymphocytes (reduced in the workers about 40%) and CD4(+)-CD45R0+ &quot;memory&quot; lymphocytes (reduced about 20%). Moreover, blood lead (correlated with urinary chromium) showed a highly significant negative correlation with the B lymphocytes. This study demonstrates that combined exposure to toxic agents produces specific modifications in the lymphocyte subsets without changes in immunoglobulins and confirms the results of previous researches showing that the exposure to lead or chromate induces reduction of lymphocytes in the peripheral blood."
1234598,Mattagajasingh and  Misra 1995,Alterations in the prooxidant and antioxidant status of human leukemic T-lymphocyte MOLT4 cells treated with potassium chromate,"The involvement of reactive oxygen species in chromate-induced genotoxicity has been postulated. Because intracellular antioxidants help in eliminating the reactive species of oxygen, we have investigated both the prooxidant and antioxidant status of human leukemic T-lymphocyte MOLT4 cells exposed to nontoxic levels of chromium(VI) in culture. The cells treated with 0-->200 microM potassium chromate in a salts/glucose medium for 2 h were found to contain significantly lower levels of both small molecular weight and macromolecular antioxidants. In particular, the levels of glutathione and ascorbate were found to decrease with increased doses of chromate exposure in a dose-dependent manner. As little as 10 microM chromate was found to decrease these small molecular weight antioxidants significantly (p < 0.01). The macromolecular antioxidants, such as glutathione peroxidase, catalase, glutathione reductase, glucose-6-phosphate dehydrogenase and superoxide dismutase were also significantly (p < 0.01) decreased by exposing the cells to as little as 10 microM chromate. Concomitantly, there was a dose-dependent increase in intracellular H2O2 accumulation in cells exposed to chromium(VI). These results indicate that chromate-induced genotoxicity may be due, at least in part, to decreased levels of intracellular antioxidants in conjunction with an increased production of the reactive oxygen species.","Alterations in the prooxidant and antioxidant status of human leukemic T-lymphocyte MOLT4 cells treated with potassium chromate Abs: The involvement of reactive oxygen species in chromate-induced genotoxicity has been postulated. Because intracellular antioxidants help in eliminating the reactive species of oxygen, we have investigated both the prooxidant and antioxidant status of human leukemic T-lymphocyte MOLT4 cells exposed to nontoxic levels of chromium(VI) in culture. The cells treated with 0-->200 microM potassium chromate in a salts/glucose medium for 2 h were found to contain significantly lower levels of both small molecular weight and macromolecular antioxidants. In particular, the levels of glutathione and ascorbate were found to decrease with increased doses of chromate exposure in a dose-dependent manner. As little as 10 microM chromate was found to decrease these small molecular weight antioxidants significantly (p < 0.01). The macromolecular antioxidants, such as glutathione peroxidase, catalase, glutathione reductase, glucose-6-phosphate dehydrogenase and superoxide dismutase were also significantly (p < 0.01) decreased by exposing the cells to as little as 10 microM chromate. Concomitantly, there was a dose-dependent increase in intracellular H2O2 accumulation in cells exposed to chromium(VI). These results indicate that chromate-induced genotoxicity may be due, at least in part, to decreased levels of intracellular antioxidants in conjunction with an increased production of the reactive oxygen species."
1234597,Stearns et al. 1995,Reduction of chromium(VI) by ascorbate leads to chromium-DNA binding and DNA strand breaks in vitro,"Chromium(VI) is a known human carcinogen which requires intracellular reduction for activation. Ascorbate (vitamin C) has been reported to function as a major reductant of Cr(VI) in animals and cell culture systems. The reaction of Cr(VI) with varying concentrations of ascorbate was studied under physiological conditions in vitro in order to determine the types of reactive intermediates produced and to evaluate the reactivity of these intermediates with DNA. Reactions of 1.8 mM Cr(VI) with 0-18 mM ascorbate at pH 7.0 in N-(2-hydroxyethyl)piperazine-N'-2-ethanesulfonic acid (HEPES; 0.10 M) and tris(hydroxymethyl)aminomethane hydrochloride (Tris.HCl; 0.050 M) buffers were studied by electron paramagnetic resonance and UV/visible spectroscopy. Cr(V) and carbon-based free radical adducts of 5,5-dimethyl-1-pyrroline 1-oxide (DMPO) were observed at 0.5 to 1 and 1 to 1 reactions of ascorbate to Cr(VI). Levels of Cr(V) were higher for reactions in HEPES buffer, and levels of carbon-based radicals were higher in Tris.HCl buffer. Levels of Cr(IV) and Cr(III) increased with increasing concentration of ascorbate in both buffers. Reaction of Cr(VI) with varying ascorbate in the presence of calf thymus DNA or pBR322 DNA resulted in Cr-DNA adducts and plasmid relaxation, respectively. Maximum binding of Cr to DNA was observed for the 1:1 reaction ratio of Cr(VI) with ascorbate in both HEPES and Tris.HCl buffers, but total Cr bound to DNA was 8-fold lower in Tris.HCl than HEPES buffer. Preincubation of Cr(VI) with ascorbate before reaction with DNA decreased Cr-DNA binding to background levels. Preincubation of Cr(III) with ascorbate resulted in only low Cr-DNA binding. Levels of Cr-DNA binding were higher with single-stranded vs double-stranded DNA. Reactions with 14C-labeled ascorbate produced no cross-linking of ascorbate to DNA. Maximum plasmid relaxation was observed for the 1:1 ascorbate to Cr(VI) ratio in both buffers; however, single-strand breaks were 2-fold higher in Tris.HCl than HEPES buffer. Reactions with plasmid in the presence of DMPO quenched formation of single-strand breaks. Interpretation of these results in light of the spectroscopic studies suggested that Cr(V) and carbon-based radicals were responsible for Cr-DNA adducts and DNA single-strand breaks, respectively.","Reduction of chromium(VI) by ascorbate leads to chromium-DNA binding and DNA strand breaks in vitro Abs: Chromium(VI) is a known human carcinogen which requires intracellular reduction for activation. Ascorbate (vitamin C) has been reported to function as a major reductant of Cr(VI) in animals and cell culture systems. The reaction of Cr(VI) with varying concentrations of ascorbate was studied under physiological conditions in vitro in order to determine the types of reactive intermediates produced and to evaluate the reactivity of these intermediates with DNA. Reactions of 1.8 mM Cr(VI) with 0-18 mM ascorbate at pH 7.0 in N-(2-hydroxyethyl)piperazine-N'-2-ethanesulfonic acid (HEPES; 0.10 M) and tris(hydroxymethyl)aminomethane hydrochloride (Tris.HCl; 0.050 M) buffers were studied by electron paramagnetic resonance and UV/visible spectroscopy. Cr(V) and carbon-based free radical adducts of 5,5-dimethyl-1-pyrroline 1-oxide (DMPO) were observed at 0.5 to 1 and 1 to 1 reactions of ascorbate to Cr(VI). Levels of Cr(V) were higher for reactions in HEPES buffer, and levels of carbon-based radicals were higher in Tris.HCl buffer. Levels of Cr(IV) and Cr(III) increased with increasing concentration of ascorbate in both buffers. Reaction of Cr(VI) with varying ascorbate in the presence of calf thymus DNA or pBR322 DNA resulted in Cr-DNA adducts and plasmid relaxation, respectively. Maximum binding of Cr to DNA was observed for the 1:1 reaction ratio of Cr(VI) with ascorbate in both HEPES and Tris.HCl buffers, but total Cr bound to DNA was 8-fold lower in Tris.HCl than HEPES buffer. Preincubation of Cr(VI) with ascorbate before reaction with DNA decreased Cr-DNA binding to background levels. Preincubation of Cr(III) with ascorbate resulted in only low Cr-DNA binding. Levels of Cr-DNA binding were higher with single-stranded vs double-stranded DNA. Reactions with 14C-labeled ascorbate produced no cross-linking of ascorbate to DNA. Maximum plasmid relaxation was observed for the 1:1 ascorbate to Cr(VI) ratio in both buffers; however, single-strand breaks were 2-fold higher in Tris.HCl than HEPES buffer. Reactions with plasmid in the presence of DMPO quenched formation of single-strand breaks. Interpretation of these results in light of the spectroscopic studies suggested that Cr(V) and carbon-based radicals were responsible for Cr-DNA adducts and DNA single-strand breaks, respectively."
1234596,Iwadare and  Arai 1995,Staining etched epoxy resin sections for light microscopy,"Staining of etched sections for light microscopy is described. Azan staining was successful after treatment with potassium dichromate and the use of concentrated dye solutions. To remove osmium for hematoxylin-eosin staining, removal by reduction with ferrocene was used instead of oxidation. Highly selective differentiation after hematoxylin staining was achieved using p-toluenesulfonic acid-DMSO. To enhance eosin staining, a 2-bromoethylamine link between eosin and the tissue was used. Ferrocene also facilitated counterstaining of nuclei with hematoxylin after the PAS reaction. Periodic acid-methenamine silver staining was carried out without modification.","Staining etched epoxy resin sections for light microscopy Abs: Staining of etched sections for light microscopy is described. Azan staining was successful after treatment with potassium dichromate and the use of concentrated dye solutions. To remove osmium for hematoxylin-eosin staining, removal by reduction with ferrocene was used instead of oxidation. Highly selective differentiation after hematoxylin staining was achieved using p-toluenesulfonic acid-DMSO. To enhance eosin staining, a 2-bromoethylamine link between eosin and the tissue was used. Ferrocene also facilitated counterstaining of nuclei with hematoxylin after the PAS reaction. Periodic acid-methenamine silver staining was carried out without modification."
1234595,Uter et al. 1995,"Patch test results with serial dilutions of nickel sulfate (with and without detergent), palladium chloride, and nickel and palladium metal plates","Clinical experience suggests the existence of different degrees of sensitivity in nickel-allergic patients. For quantification of this phenomenon, 462 consecutive patients with previously diagnosed or strongly suspected nickel allergy were tested with serial dilution patch tests with 5 ppm to 5% nickel sulfate in pet. (Ni), and 5 ppm to 1% nickel sulfate in pet. with 1% detergent (Ni/D). Additionally, nickel and palladium metal plates were tested in 103, and cobalt salts, dichromate and palladium chloride (PdCl2) in most patients. 332 patients reacted positively to Ni or Ni/D. The influence of a concomitantly administered detergent was not significant. A significant correlation was found between positive reactions to low concentrations of Ni (or Ni/D), i.e., 0.1% or less (N = 166), and concomitant reactions to nickel metal plates, cobalt salts and PdCl2 and a history of ear piercing with metal intolerance. The clinical relevance of reactions to PdCl2 is at present not clear. A subgroup of nickel-allergic patients with &quot;high sensitivity&quot; can be defined. In future studies further addressing the clinical relevance of high versus low sensitivity, patch testing with 0.01, 0.1, 1.0 and 5% nickel sulfate in pet. is recommended instead of routine tests with 5% only.","Patch test results with serial dilutions of nickel sulfate (with and without detergent), palladium chloride, and nickel and palladium metal plates Abs: Clinical experience suggests the existence of different degrees of sensitivity in nickel-allergic patients. For quantification of this phenomenon, 462 consecutive patients with previously diagnosed or strongly suspected nickel allergy were tested with serial dilution patch tests with 5 ppm to 5% nickel sulfate in pet. (Ni), and 5 ppm to 1% nickel sulfate in pet. with 1% detergent (Ni/D). Additionally, nickel and palladium metal plates were tested in 103, and cobalt salts, dichromate and palladium chloride (PdCl2) in most patients. 332 patients reacted positively to Ni or Ni/D. The influence of a concomitantly administered detergent was not significant. A significant correlation was found between positive reactions to low concentrations of Ni (or Ni/D), i.e., 0.1% or less (N = 166), and concomitant reactions to nickel metal plates, cobalt salts and PdCl2 and a history of ear piercing with metal intolerance. The clinical relevance of reactions to PdCl2 is at present not clear. A subgroup of nickel-allergic patients with &quot;high sensitivity&quot; can be defined. In future studies further addressing the clinical relevance of high versus low sensitivity, patch testing with 0.01, 0.1, 1.0 and 5% nickel sulfate in pet. is recommended instead of routine tests with 5% only."
1234594,Serra-Baldrich et al. 1995,Contact dermatitis: clinical review of 800 patients tested using the standard European series,"The results of the use of the European Standard Series on 800 patients suffering from Contact Dermatitis, including occupational Dermatosis is reported. This work also attempts to provide insight into the interests and difficulties of carrying out an epidemiological study in an Allergy Centre and Immunology Clinic. All the patients underwent a Patch Test following the guidelines laid out by the International Contact Dermatitis Research Group. The results of the patch tests were positive in 462 patients (57.7%) and negative in 338 cases (42.3%). The agents responsible for the symptoms in our study were as follows: metals (33%), parafenilen-diamine (13.9%), cobalt (13.3%), perfumes (5.5%), benzocaine (5.4%) and potassium dichromate (5.4%). In this study 72 patients were verified to have Occupational Dermatosis, corresponding mainly to the following occupational sectors: metal industry workers, hairdressers and bakers and pastry makers.","Contact dermatitis: clinical review of 800 patients tested using the standard European series Abs: The results of the use of the European Standard Series on 800 patients suffering from Contact Dermatitis, including occupational Dermatosis is reported. This work also attempts to provide insight into the interests and difficulties of carrying out an epidemiological study in an Allergy Centre and Immunology Clinic. All the patients underwent a Patch Test following the guidelines laid out by the International Contact Dermatitis Research Group. The results of the patch tests were positive in 462 patients (57.7%) and negative in 338 cases (42.3%). The agents responsible for the symptoms in our study were as follows: metals (33%), parafenilen-diamine (13.9%), cobalt (13.3%), perfumes (5.5%), benzocaine (5.4%) and potassium dichromate (5.4%). In this study 72 patients were verified to have Occupational Dermatosis, corresponding mainly to the following occupational sectors: metal industry workers, hairdressers and bakers and pastry makers."
1234593,Kaiwar and  Rao 1995,In vitro reduction of Cr(VI) by low molecular weight biomimetic components: a comparative study using UV-Vis spectroscopy,"Chromium(VI) reduction has been carried out by a variety of molecules of cellular and soil importance, such as thiol containing ones, ascorbic acid, saccharides and their derivatives, and nucleotides and their components using absorption spectroscopy. Based on the absorption data, the reductive abilities of these molecules have been obtained and the trend has been found to be ascorbic acid &gt; thiols &gt; saccharides &gt; nucleotides.","In vitro reduction of Cr(VI) by low molecular weight biomimetic components: a comparative study using UV-Vis spectroscopy Abs: Chromium(VI) reduction has been carried out by a variety of molecules of cellular and soil importance, such as thiol containing ones, ascorbic acid, saccharides and their derivatives, and nucleotides and their components using absorption spectroscopy. Based on the absorption data, the reductive abilities of these molecules have been obtained and the trend has been found to be ascorbic acid &gt; thiols &gt; saccharides &gt; nucleotides."
1234592,Yokozeki et al. 1995,Experimental study for the development of an in vitro test for contact allergens. 1. Primary activation of hapten-specific T cells by hapten-conjugated epidermal cells,"We conducted a study on the primary in vitro activation of T cells from non-sensitized mice by using hapten-conjugated Pam 212 cells (keratinocyte cell line). Furthermore, we attempted to develop a simple, quantitative in vitro test to assess the sensitizing potency of contact allergens and applied it to determine the stimulation index (SI) of various chemicals with known degrees of sensitizing potency. Monolayered Pam 212 cells were incubated with a variety of chemicals exhibiting allergenic potential. Washed and fixed T cells depleted of autoreactive T cells and macrophages from spleens of nonsensitized Balb/c mice were cocultured for 5 days with those monolayered Pam cells conjugated with chemicals. They were then harvested and restimulated with mitomycin-C-treated spleen cells conjugated with chemicals in 96-well culture plates to inhibit the proliferation of stimulator cells. We evaluated the sensitizing potency of the following chemicals: oxazolone, TNBS, DNFB and FITC (strong sensitizers); p-phenylendiamine (p-PD), nickel chloride and potassium dichromate (potent sensitizers); betamethasone and budesonide (corticosteroids), and methyl salicylate (MS) as an irritant. T cells sensitized in vitro with TNP-Pam cells and macrophages demonstrated antigen-specific proliferation when restimulated in vitro with mitomycin-C-treated TNP-spleen cells. Subcutaneous injection of these T cells induced contact sensitivity in vivo in an antigen-specific fashion. While T cells cocultured with TNP-3T3 could not be activated even in the presence of macrophages. The SI of strong sensitizers was about 4.00 and that of p-PD was 2.36. The SIs of budesonide, betamethasone and MS were 1.62, 0.98 and 1.21, respectively.(ABSTRACT TRUNCATED AT 250 WORDS)","Experimental study for the development of an in vitro test for contact allergens. 1. Primary activation of hapten-specific T cells by hapten-conjugated epidermal cells Abs: We conducted a study on the primary in vitro activation of T cells from non-sensitized mice by using hapten-conjugated Pam 212 cells (keratinocyte cell line). Furthermore, we attempted to develop a simple, quantitative in vitro test to assess the sensitizing potency of contact allergens and applied it to determine the stimulation index (SI) of various chemicals with known degrees of sensitizing potency. Monolayered Pam 212 cells were incubated with a variety of chemicals exhibiting allergenic potential. Washed and fixed T cells depleted of autoreactive T cells and macrophages from spleens of nonsensitized Balb/c mice were cocultured for 5 days with those monolayered Pam cells conjugated with chemicals. They were then harvested and restimulated with mitomycin-C-treated spleen cells conjugated with chemicals in 96-well culture plates to inhibit the proliferation of stimulator cells. We evaluated the sensitizing potency of the following chemicals: oxazolone, TNBS, DNFB and FITC (strong sensitizers); p-phenylendiamine (p-PD), nickel chloride and potassium dichromate (potent sensitizers); betamethasone and budesonide (corticosteroids), and methyl salicylate (MS) as an irritant. T cells sensitized in vitro with TNP-Pam cells and macrophages demonstrated antigen-specific proliferation when restimulated in vitro with mitomycin-C-treated TNP-spleen cells. Subcutaneous injection of these T cells induced contact sensitivity in vivo in an antigen-specific fashion. While T cells cocultured with TNP-3T3 could not be activated even in the presence of macrophages. The SI of strong sensitizers was about 4.00 and that of p-PD was 2.36. The SIs of budesonide, betamethasone and MS were 1.62, 0.98 and 1.21, respectively.(ABSTRACT TRUNCATED AT 250 WORDS)"
1234591,Moen et al. 1995,Occupational exposure of deck crews to carcinogenic agents on crude oil tankers,"Occupational exposure to carcinogenic agents on the decks on six Norwegian crude oil tankers was examined in five harbors. The purpose of the study was to evaluate the need for improving the working environment on deck on these tankers. Technical arrangements and the work itself on the deck were observed during loading or unloading. Occupational monitoring was performed by active sampling of benzene, polyaromatic hydrocarbons, and some aldehydes. The crew answered a questionnaire concerning their work, use of protective equipment, and occurrence of acute symptoms. The levels of air-borne carcinogenic agents were low, probably due to closed loading systems on all tankers. However, the seamen reported discomfort during the work that may be related to other chemical agents in the cargo. The seamen were frequently painting with lead chromate paint without using personal protective equipment. This type of chemical exposure should be evaluated.","Occupational exposure of deck crews to carcinogenic agents on crude oil tankers Abs: Occupational exposure to carcinogenic agents on the decks on six Norwegian crude oil tankers was examined in five harbors. The purpose of the study was to evaluate the need for improving the working environment on deck on these tankers. Technical arrangements and the work itself on the deck were observed during loading or unloading. Occupational monitoring was performed by active sampling of benzene, polyaromatic hydrocarbons, and some aldehydes. The crew answered a questionnaire concerning their work, use of protective equipment, and occurrence of acute symptoms. The levels of air-borne carcinogenic agents were low, probably due to closed loading systems on all tankers. However, the seamen reported discomfort during the work that may be related to other chemical agents in the cargo. The seamen were frequently painting with lead chromate paint without using personal protective equipment. This type of chemical exposure should be evaluated."
1234590,Merritt and  Brown 1995,Release of hexavalent chromium from corrosion of stainless steel and cobalt-chromium alloys,"Experiments were undertaken to determine whether hexavalent chromium was released during corrosion of orthopedic implants. Uptake of chromium (Cr) by cells and separation using amberlite resin were the methods used to determine that hexavalent Cr was present. We used salts of chromium as trivalent chromium (chromic chloride) and hexavalent chromium (potassium dichromate) to verify that the amberlite separation technique separates hexavalent Cr into the upper phase and trivalent Cr into the lower phase. The use of the salts also verified that only the hexavalent Cr became red blood cell-associated and that most of this was intracellular rather than membrane bound. The use of the amberlite separation technique demonstrated that the hexavalent Cr in the red blood cells was rapidly reduced to trivalent Cr. Cellular uptake of chromium was documented in red blood cells following corrosion of stainless-steel and cobalt-chromium implants in vivo, in the red blood cells of patients undergoing total joint revisions, and in fibroblasts subjected to products of fretting corrosion of stainless-steel and cobalt-chromium implants. Thus, corrosion of implants can lead to the release of the biologically active hexavalent chromium into the body. This chromium is rapidly reduced to trivalent chromium in cells.","Release of hexavalent chromium from corrosion of stainless steel and cobalt-chromium alloys Abs: Experiments were undertaken to determine whether hexavalent chromium was released during corrosion of orthopedic implants. Uptake of chromium (Cr) by cells and separation using amberlite resin were the methods used to determine that hexavalent Cr was present. We used salts of chromium as trivalent chromium (chromic chloride) and hexavalent chromium (potassium dichromate) to verify that the amberlite separation technique separates hexavalent Cr into the upper phase and trivalent Cr into the lower phase. The use of the salts also verified that only the hexavalent Cr became red blood cell-associated and that most of this was intracellular rather than membrane bound. The use of the amberlite separation technique demonstrated that the hexavalent Cr in the red blood cells was rapidly reduced to trivalent Cr. Cellular uptake of chromium was documented in red blood cells following corrosion of stainless-steel and cobalt-chromium implants in vivo, in the red blood cells of patients undergoing total joint revisions, and in fibroblasts subjected to products of fretting corrosion of stainless-steel and cobalt-chromium implants. Thus, corrosion of implants can lead to the release of the biologically active hexavalent chromium into the body. This chromium is rapidly reduced to trivalent chromium in cells."
1234588,Arrowood et al. 1995,A new method for evaluating experimental cryptosporidial parasite loads using immunofluorescent flow cytometry,"A flow cytometric method for the quantification of Cryptosporidium parvum oocysts in stool specimens was developed to replace conventional microscopic immunofluorescent assays. Fecal pellets were collected from control (uninfected) severe combined immune-deficient mice, suspended in 2.5% potassium dichromate at a ratio of 400 microliter per pellet, and homogenized by vortexing. Purified oocytes were added to the samples (10(5), 10(4), 10(3), and 10(2)/ml). Aliquots (200 microliters) of the vortexed samples were centrifuged over microscale discontinuous sucrose gradients. The oocyst-containing fractions were collected, washed, and incubated with an oocyst-specific monoclonal antibody (labeled with fluorescein isothiocyanate) for 30 min at 37 degrees C. Sample volumes were adjusted to 600 microliters with phosphate-buffered saline and assayed by using logical gating of forward/side scatter and fluorescence signal on a flow cytometer. Seeded samples showed a linear correlation with the number of oocysts recovered from the gradients. Analyses of stool samples from chronically infected mice demonstrated that the flow cytometry method was approximately 10 times more sensitive than conventional immunofluorescent assays.","A new method for evaluating experimental cryptosporidial parasite loads using immunofluorescent flow cytometry Abs: A flow cytometric method for the quantification of Cryptosporidium parvum oocysts in stool specimens was developed to replace conventional microscopic immunofluorescent assays. Fecal pellets were collected from control (uninfected) severe combined immune-deficient mice, suspended in 2.5% potassium dichromate at a ratio of 400 microliter per pellet, and homogenized by vortexing. Purified oocytes were added to the samples (10(5), 10(4), 10(3), and 10(2)/ml). Aliquots (200 microliters) of the vortexed samples were centrifuged over microscale discontinuous sucrose gradients. The oocyst-containing fractions were collected, washed, and incubated with an oocyst-specific monoclonal antibody (labeled with fluorescein isothiocyanate) for 30 min at 37 degrees C. Sample volumes were adjusted to 600 microliters with phosphate-buffered saline and assayed by using logical gating of forward/side scatter and fluorescence signal on a flow cytometer. Seeded samples showed a linear correlation with the number of oocysts recovered from the gradients. Analyses of stool samples from chronically infected mice demonstrated that the flow cytometry method was approximately 10 times more sensitive than conventional immunofluorescent assays."
1234587,Lei et al. 1995,Study on DNA-protein crosslinks induced by chromate and nickel compounds in vivo with 125I-postlabelling assay,"In an attempt to develop biomarkers of chromate and nickel exposure, we have used a rapid, simple and sensitive 125I-postlabelling assay to detect the formation of DNA-protein crosslinks (DPCs) in different tissues from male Sprague-Dawley rats exposed i.p. to potassium chromate (K2CrO4) and nickel chloride (NiCl2). The results demonstrated that 20 h after rats were injected i.p. with these agents, DPCs were observed in WBC, liver and kidney of rats treated with K2CrO4 in doses ranging from 10 to 40 mg/kg body wt. There was a dose-dependent relationship between chromate exposure and DPCs in WBC and liver, but no DPC increase was shown in lung. In the same way, DPCs were found in WBC and lung of rats treated with NiCl2 in doses ranging from 10 to 30 mg/kg in a dose-dependent manner. The formation of DPCs in different tissues was also observed following repeated exposure of rats to K2CrO4 and NiCl2 (10 mg/kg, i.p.) for 3 weeks. These results were similar with the single dose. It is indicated that chromate and nickel compounds possibly cause DNA or protein damage to form DPCs, suggesting DPCs might be useful as a biomarker for quantitative K2CrO4 and NiCl2 exposure and genotoxic lesions. In addition, WBC were shown to be more sensitive to chromate(VI) and nickel(II) induced DPCs than other targets. There were significant correlations between DPCs induced by K2CrO4 in WBC and liver, and by NiCl2 generated DPCs in WBC and lung, indicating that DPCs in WBC may be a good surrogate for some internal organs of humans exposed to chromate(VI) and nickel(II) compounds.","Study on DNA-protein crosslinks induced by chromate and nickel compounds in vivo with 125I-postlabelling assay Abs: In an attempt to develop biomarkers of chromate and nickel exposure, we have used a rapid, simple and sensitive 125I-postlabelling assay to detect the formation of DNA-protein crosslinks (DPCs) in different tissues from male Sprague-Dawley rats exposed i.p. to potassium chromate (K2CrO4) and nickel chloride (NiCl2). The results demonstrated that 20 h after rats were injected i.p. with these agents, DPCs were observed in WBC, liver and kidney of rats treated with K2CrO4 in doses ranging from 10 to 40 mg/kg body wt. There was a dose-dependent relationship between chromate exposure and DPCs in WBC and liver, but no DPC increase was shown in lung. In the same way, DPCs were found in WBC and lung of rats treated with NiCl2 in doses ranging from 10 to 30 mg/kg in a dose-dependent manner. The formation of DPCs in different tissues was also observed following repeated exposure of rats to K2CrO4 and NiCl2 (10 mg/kg, i.p.) for 3 weeks. These results were similar with the single dose. It is indicated that chromate and nickel compounds possibly cause DNA or protein damage to form DPCs, suggesting DPCs might be useful as a biomarker for quantitative K2CrO4 and NiCl2 exposure and genotoxic lesions. In addition, WBC were shown to be more sensitive to chromate(VI) and nickel(II) induced DPCs than other targets. There were significant correlations between DPCs induced by K2CrO4 in WBC and liver, and by NiCl2 generated DPCs in WBC and lung, indicating that DPCs in WBC may be a good surrogate for some internal organs of humans exposed to chromate(VI) and nickel(II) compounds."
1234586,Escolar et al. 1995,Measurement of the concentrations of solutions through chromatic systems,"After a careful check of the response linearity of the spectrophotometer in absorbances and transmittances at wavelengths between 250 and 550 nm with potassium dichromate, the influence of the concentration of solutions on the tristimulus coordinates and the coordinates of the CIE 1931 (Commission Internationale de l'Éclairage) and CIELAB colorimetric systems was analyzed. How to use the value of only some chromatic coordinates to obtain a sample's concentration simultaneously is also shown.","Measurement of the concentrations of solutions through chromatic systems Abs: After a careful check of the response linearity of the spectrophotometer in absorbances and transmittances at wavelengths between 250 and 550 nm with potassium dichromate, the influence of the concentration of solutions on the tristimulus coordinates and the coordinates of the CIE 1931 (Commission Internationale de l'Éclairage) and CIELAB colorimetric systems was analyzed. How to use the value of only some chromatic coordinates to obtain a sample's concentration simultaneously is also shown."
1234585,Freeman 1995,Chromate allergy from 'antifreeze-antiboil',A diesel mechanic developed hand dermatitis after more than 3 years in the trade. Patch testing showed positive reactions to chromate and cobalt. Potassium dichromate is added to antifreeze-antiboil as a corrosion inhibitor.,Chromate allergy from 'antifreeze-antiboil' Abs: A diesel mechanic developed hand dermatitis after more than 3 years in the trade. Patch testing showed positive reactions to chromate and cobalt. Potassium dichromate is added to antifreeze-antiboil as a corrosion inhibitor.
1234584,Junaid et al. 1995,Chromium fetotoxicity in mice during late pregnancy,"Female mice received 250, 500 or 750 ppm chromium (VI) as potassium dichromate in drinking water on days 14 to 19 of pregnancy. Gestational weight gain of mothers, fetal weight and crown-rump length decreased in the 500 and 750 ppm groups. The high-dose group also had significantly higher incidences of postimplantation loss. Significant increases in drooping wrists, subdermal hemorrhagic patches, kinky and short tails, and reduced ossification were also found in the 750 ppm group. Chromium levels were increased in a dose-dependent manner in maternal blood and placenta and in fetuses. Our study suggests a risk to the developing fetus if the mother is exposed to high concentrations of chromium (VI) during pregnancy.","Chromium fetotoxicity in mice during late pregnancy Abs: Female mice received 250, 500 or 750 ppm chromium (VI) as potassium dichromate in drinking water on days 14 to 19 of pregnancy. Gestational weight gain of mothers, fetal weight and crown-rump length decreased in the 500 and 750 ppm groups. The high-dose group also had significantly higher incidences of postimplantation loss. Significant increases in drooping wrists, subdermal hemorrhagic patches, kinky and short tails, and reduced ossification were also found in the 750 ppm group. Chromium levels were increased in a dose-dependent manner in maternal blood and placenta and in fetuses. Our study suggests a risk to the developing fetus if the mother is exposed to high concentrations of chromium (VI) during pregnancy."
1234583,Ye et al. 1995,Chromium(VI)-induced nuclear factor-kappa B activation in intact cells via free radical reactions,"Incubation of chromium(VI) [Cr(VI)] with cultured Jurkat cells resulted in activation of DNA binding activity of the nuclear factor (NF)-kappa B. In a combination with glutathione reductase, a Cr(VI) reducing agent, Cr(VI) expressed an enhanced activity in induction of NF-kappa B. This activation of NF-kappa B was decreased by a metal chelator, diethylene-triaminepentaacetic acid or catalase, but increased by superoxide dismutase. Addition of Mn2+, which reacts with Cr(IV) and inhibits Cr(IV)-mediated hydroxyl radical (.OH) generation via Fenton-like reaction, attenuated the activation of NF-kappa B. Sodium formate, an .OH radical scavenger, also inhibited the activation. Electron spin resonance measurements showed that the incubation of Cr(VI) with intact Jurkat cells generated reactive Cr(V) intermediate. Glutathione reductase and NADPH enhanced Cr(V) generation. Electron spin resonance spin trapping measurements using 5,5-dimethyl-1-pyrroline N-oxide (DMPO) as a spin trapping agent provided evidence that the incubation of Cr(VI) with the Jurkat cells in the presence of glutathione reductase generated .OH radicals. H2O2 enhanced .OH radical generation and also enhanced Cr(V) formation, indicating the role of Cr(IV) in .OH radical generation. We conclude that Cr(VI) can activate NF-kappa B in vitro via Cr(IV)-mediated free radical reactions. We hypothesize that Cr(VI)-mediated NF-kappa B activation may be involved in the mechanism of Cr(VI)-induced carcinogenicity.","Chromium(VI)-induced nuclear factor-kappa B activation in intact cells via free radical reactions Abs: Incubation of chromium(VI) [Cr(VI)] with cultured Jurkat cells resulted in activation of DNA binding activity of the nuclear factor (NF)-kappa B. In a combination with glutathione reductase, a Cr(VI) reducing agent, Cr(VI) expressed an enhanced activity in induction of NF-kappa B. This activation of NF-kappa B was decreased by a metal chelator, diethylene-triaminepentaacetic acid or catalase, but increased by superoxide dismutase. Addition of Mn2+, which reacts with Cr(IV) and inhibits Cr(IV)-mediated hydroxyl radical (.OH) generation via Fenton-like reaction, attenuated the activation of NF-kappa B. Sodium formate, an .OH radical scavenger, also inhibited the activation. Electron spin resonance measurements showed that the incubation of Cr(VI) with intact Jurkat cells generated reactive Cr(V) intermediate. Glutathione reductase and NADPH enhanced Cr(V) generation. Electron spin resonance spin trapping measurements using 5,5-dimethyl-1-pyrroline N-oxide (DMPO) as a spin trapping agent provided evidence that the incubation of Cr(VI) with the Jurkat cells in the presence of glutathione reductase generated .OH radicals. H2O2 enhanced .OH radical generation and also enhanced Cr(V) formation, indicating the role of Cr(IV) in .OH radical generation. We conclude that Cr(VI) can activate NF-kappa B in vitro via Cr(IV)-mediated free radical reactions. We hypothesize that Cr(VI)-mediated NF-kappa B activation may be involved in the mechanism of Cr(VI)-induced carcinogenicity."
1234582,Kundu et al. 1995,"Effects of Cr (VI) on ATPases in the brain and muscle of mudskipper, Boleophthalmus dentatus",BIOSIS COPYRIGHT: BIOL ABS. RRM RESEARCH ARTICLE BOLEOPHTHALMUS-DENTATUS CHROMIUMVI HEAVY METALS POTASSIUM DICHROMATE CALCIUM-ATPASE MAGNESIUM-ATPASE CALCIUM-BICARBONATE ATPASE MAGNESIUM-BICARBONATE ATPASE SODIUM-POTASSIUM ATPASE ENVIRONMENTAL CONTAMINATION,"Effects of Cr (VI) on ATPases in the brain and muscle of mudskipper, Boleophthalmus dentatus Abs: BIOSIS COPYRIGHT: BIOL ABS. RRM RESEARCH ARTICLE BOLEOPHTHALMUS-DENTATUS CHROMIUMVI HEAVY METALS POTASSIUM DICHROMATE CALCIUM-ATPASE MAGNESIUM-ATPASE CALCIUM-BICARBONATE ATPASE MAGNESIUM-BICARBONATE ATPASE SODIUM-POTASSIUM ATPASE ENVIRONMENTAL CONTAMINATION"
1234581,El-Rab and  Al-Sheikh 1995,"Is the European standard series suitable for patch testing in Riyadh, Saudi Arabia?","Due to the lack of a regional patch test series in our geographical area, the suitability of the European standard series was evaluated by patch testing dermatitis patients in Riyadh, Saudi Arabia. Of 240 consecutive patients with various forms of dermatitis, 136 (57%) showed 1 or more positive patch tests, women, 74 (54%), slightly outnumbering men, 62 (46%). Positive reactions were found to 21 of the 22 items in the test series. Sensitization was most common to nickel sulfate (51 = 37.5%), potassium dichromate (48 = 35%) and cobalt chloride (43 = 32%) The frequency of sensitization to nickel was higher in women (41 = 30%) while that to dichromate was higher in men (39 = 29%). Less reactions were found to fragrance mix (21 = 15%), formaldehyde (15 = 11%) and neomycin sulfate (15 = 11%). Sensitization to other allergens ranged between 10 and 1%. Less than 1% of patients (0.7%) reacted to benzocaine and none to primin. The frequency of occurrence of multiple sensitivities is also presented. We conclude that the European standard series is suitable for patch testing dermatitis patients in our region, with the exception of benzocaine and primin. The addition of 3 allergens that could be of local relevance is discussed.","Is the European standard series suitable for patch testing in Riyadh, Saudi Arabia? Abs: Due to the lack of a regional patch test series in our geographical area, the suitability of the European standard series was evaluated by patch testing dermatitis patients in Riyadh, Saudi Arabia. Of 240 consecutive patients with various forms of dermatitis, 136 (57%) showed 1 or more positive patch tests, women, 74 (54%), slightly outnumbering men, 62 (46%). Positive reactions were found to 21 of the 22 items in the test series. Sensitization was most common to nickel sulfate (51 = 37.5%), potassium dichromate (48 = 35%) and cobalt chloride (43 = 32%) The frequency of sensitization to nickel was higher in women (41 = 30%) while that to dichromate was higher in men (39 = 29%). Less reactions were found to fragrance mix (21 = 15%), formaldehyde (15 = 11%) and neomycin sulfate (15 = 11%). Sensitization to other allergens ranged between 10 and 1%. Less than 1% of patients (0.7%) reacted to benzocaine and none to primin. The frequency of occurrence of multiple sensitivities is also presented. We conclude that the European standard series is suitable for patch testing dermatitis patients in our region, with the exception of benzocaine and primin. The addition of 3 allergens that could be of local relevance is discussed."
1234580,Boussiquet-Leroux et al. 1995,Evaluation of lymphocyte proliferation by immunohistochemistry in the local lymph node assay,"A modified version of the local lymph node assay (LLNA) is presented, using bromodeoxyuridine to label proliferating lymphocytes. Cell counting is done on mid-sagittal sections of individual nodes under light microscopy. Two irritants (sodium lauryl sulfate and salicylic acid), four allergens of various sensitizing potential (potassium dichromate, 4-chloroaniline, neomycin sulfate and nickel sulfate) and one chemical of unknown sensitizing potential (ethyl 3-aminobenzoate) were tested either in the short protocol using three daily topical applications and/or in the long protocol with a pre-exposure step under an occluded patch. A weak T cell proliferation was noted with both irritants in the short protocol, but not in the long protocol. Potassium dichromate induced a strong proliferative response in the short protocol. A lesser sensitizing potential was detected for 4-chloroaniline, ethyl 3-aminobenzoate and neomycin sulfate but only in the long protocol. Nickel sulfate was negative in both protocols. The long protocol was the most valuable for weak or moderate sensitizers. Histological examination of nodes ruled out intercurrent processes. The present procedure offers several advantages. The use of a non-isotopic marker enables this test to be run in a routine safety assessment department and allows the preparation of permanent slides. An increased specificity is obtained by restricting cell counting to the paracortex. Moreover, the collection of individual data permits statistical analysis of the results. This method is sensitive and reproducible and may be viewed as a useful adjunct to the LLNA.","Evaluation of lymphocyte proliferation by immunohistochemistry in the local lymph node assay Abs: A modified version of the local lymph node assay (LLNA) is presented, using bromodeoxyuridine to label proliferating lymphocytes. Cell counting is done on mid-sagittal sections of individual nodes under light microscopy. Two irritants (sodium lauryl sulfate and salicylic acid), four allergens of various sensitizing potential (potassium dichromate, 4-chloroaniline, neomycin sulfate and nickel sulfate) and one chemical of unknown sensitizing potential (ethyl 3-aminobenzoate) were tested either in the short protocol using three daily topical applications and/or in the long protocol with a pre-exposure step under an occluded patch. A weak T cell proliferation was noted with both irritants in the short protocol, but not in the long protocol. Potassium dichromate induced a strong proliferative response in the short protocol. A lesser sensitizing potential was detected for 4-chloroaniline, ethyl 3-aminobenzoate and neomycin sulfate but only in the long protocol. Nickel sulfate was negative in both protocols. The long protocol was the most valuable for weak or moderate sensitizers. Histological examination of nodes ruled out intercurrent processes. The present procedure offers several advantages. The use of a non-isotopic marker enables this test to be run in a routine safety assessment department and allows the preparation of permanent slides. An increased specificity is obtained by restricting cell counting to the paracortex. Moreover, the collection of individual data permits statistical analysis of the results. This method is sensitive and reproducible and may be viewed as a useful adjunct to the LLNA."
1234579,Kimber et al. 1995,An international evaluation of the murine local lymph node assay and comparison of modified procedures,"The murine local lymph node assay is a predictive test for the identification of skin-sensitizing chemicals. The method has been the subject both of national inter-laboratory studies and of extensive comparisons with guinea pig tests. In the investigations reported here, the local lymph node assay has been evaluated further in the context of an international study comprising five independent laboratories. In addition, the influence of minor modifications to the standard assay procedure on the performance of the test has been examined. The modified procedures investigated were exposure of mice for 4 rather than 3 consecutive days, excision of lymph nodes 4 rather than 5 days after the initiation of exposure and the use of an alternative isotope. All five laboratories, irrespective of whether the standard or a modified protocol was used, were able to identify accurately, and with comparable sensitivity, potassium dichromate and 2,4-dinitrochlorobenzene as skin sensitizers. Using standard criteria, none of the laboratories recorded positive responses with methyl salicylate, a non-sensitizer. In the standard protocol, lymph nodes are pooled for each experimental group and the vigor of responses measured as a stimulation index relative to vehicle controls. A stimulation index of 3 or greater is considered to indicate skin-sensitizing potential. One further modification adopted by three of the laboratories was to analyze nodes from individual animals and, thereby, permit statistical evaluation. This allowed a direct comparison of statistical significance with the conventional stimulation index as criteria for a positive response. The data indicate that, while statistical evaluation may provide, in some instances, for small increases in sensitivity, this may be at the expense of some loss of selectivity. There are, however, insufficient data presently to draw firm conclusions regarding the relative value of statistical analysis. These studies demonstrate that the local lymph node assay is sufficiently robust to accommodate minor procedural and technical modifications without material changes in test performance.","An international evaluation of the murine local lymph node assay and comparison of modified procedures Abs: The murine local lymph node assay is a predictive test for the identification of skin-sensitizing chemicals. The method has been the subject both of national inter-laboratory studies and of extensive comparisons with guinea pig tests. In the investigations reported here, the local lymph node assay has been evaluated further in the context of an international study comprising five independent laboratories. In addition, the influence of minor modifications to the standard assay procedure on the performance of the test has been examined. The modified procedures investigated were exposure of mice for 4 rather than 3 consecutive days, excision of lymph nodes 4 rather than 5 days after the initiation of exposure and the use of an alternative isotope. All five laboratories, irrespective of whether the standard or a modified protocol was used, were able to identify accurately, and with comparable sensitivity, potassium dichromate and 2,4-dinitrochlorobenzene as skin sensitizers. Using standard criteria, none of the laboratories recorded positive responses with methyl salicylate, a non-sensitizer. In the standard protocol, lymph nodes are pooled for each experimental group and the vigor of responses measured as a stimulation index relative to vehicle controls. A stimulation index of 3 or greater is considered to indicate skin-sensitizing potential. One further modification adopted by three of the laboratories was to analyze nodes from individual animals and, thereby, permit statistical evaluation. This allowed a direct comparison of statistical significance with the conventional stimulation index as criteria for a positive response. The data indicate that, while statistical evaluation may provide, in some instances, for small increases in sensitivity, this may be at the expense of some loss of selectivity. There are, however, insufficient data presently to draw firm conclusions regarding the relative value of statistical analysis. These studies demonstrate that the local lymph node assay is sufficiently robust to accommodate minor procedural and technical modifications without material changes in test performance."
1234578,Ueno et al. 1995,Formation of paramagnetic chromium in liver of mice treated with dichromate (VI),"The formation of paramagnetic chromium in the liver of male mice dosed with K2Cr2O7 (10, 20, and 40 mg Cr/kg) by a single ip injection was investigated by electron spin resonance (ESR) spectrometry. Both Cr(V) and Cr(III) complexes were detected in the mice livers at 15 min to 12 hr after Cr(VI) injection. The time course (15 min-12 hr) for the formation of paramagnetic Cr revealed that the hepatic levels of Cr(V) complexes decreased quickly during the first hour but decreased more slowly over the next 11 hr. However, in contrast to Cr(V), Cr(III) complexes appeared to persist for 12 hr after Cr(VI) treatment based on figures of Cr(III) signal. Thus, Cr(III) may be the ultimate form following reduction of Cr(VI) in liver. The total Cr content in liver of mice dosed with dichromate was also increased in a dose-dependent fashion (10-40 mg Cr/kg). However, Cr content in liver remained at similar levels for 15 min-6 hr, and slightly decreased at 12 hr after Cr(VI) injection. Under the same experimental conditions, hepatotoxicity, as estimated by the increase of serum ornithine carbamyl transferase activity, appeared at 3 hr after 20 and 40 mg Cr/kg of Cr(VI) injection, while 10 mg Cr/kg of Cr(VI) produced no hepatotoxicity even at 12 hr. Predosing with phenobarbital, which increased the hepatic levels of cytochrome P450, resulted in a decrease of the levels of Cr(V) and in a small increase of Cr content, without affecting Cr(VI) hepatotoxicity. On the other hand, pretreatment with buthionine sulfoximine, which depleted hepatic glutathione (GSH) levels, caused a decrease of Cr(VI) hepatotoxicity, but the levels of Cr(V) and Cr in the liver remained unchanged. These results demonstrated that in vivo formation of paramagnetic Cr, in particular Cr(V), in liver of mice is clearly detected and quantified by ESR spectrometry and that hepatic levels of cytochrome P450 and GSH are associated with the induction of biological effects by Cr(VI) in liver in vivo. The results also suggested that the formation of Cr(V) was not the only mechanism involved in the induction of hepatotoxicity by Cr(VI) compounds.","Formation of paramagnetic chromium in liver of mice treated with dichromate (VI) Abs: The formation of paramagnetic chromium in the liver of male mice dosed with K2Cr2O7 (10, 20, and 40 mg Cr/kg) by a single ip injection was investigated by electron spin resonance (ESR) spectrometry. Both Cr(V) and Cr(III) complexes were detected in the mice livers at 15 min to 12 hr after Cr(VI) injection. The time course (15 min-12 hr) for the formation of paramagnetic Cr revealed that the hepatic levels of Cr(V) complexes decreased quickly during the first hour but decreased more slowly over the next 11 hr. However, in contrast to Cr(V), Cr(III) complexes appeared to persist for 12 hr after Cr(VI) treatment based on figures of Cr(III) signal. Thus, Cr(III) may be the ultimate form following reduction of Cr(VI) in liver. The total Cr content in liver of mice dosed with dichromate was also increased in a dose-dependent fashion (10-40 mg Cr/kg). However, Cr content in liver remained at similar levels for 15 min-6 hr, and slightly decreased at 12 hr after Cr(VI) injection. Under the same experimental conditions, hepatotoxicity, as estimated by the increase of serum ornithine carbamyl transferase activity, appeared at 3 hr after 20 and 40 mg Cr/kg of Cr(VI) injection, while 10 mg Cr/kg of Cr(VI) produced no hepatotoxicity even at 12 hr. Predosing with phenobarbital, which increased the hepatic levels of cytochrome P450, resulted in a decrease of the levels of Cr(V) and in a small increase of Cr content, without affecting Cr(VI) hepatotoxicity. On the other hand, pretreatment with buthionine sulfoximine, which depleted hepatic glutathione (GSH) levels, caused a decrease of Cr(VI) hepatotoxicity, but the levels of Cr(V) and Cr in the liver remained unchanged. These results demonstrated that in vivo formation of paramagnetic Cr, in particular Cr(V), in liver of mice is clearly detected and quantified by ESR spectrometry and that hepatic levels of cytochrome P450 and GSH are associated with the induction of biological effects by Cr(VI) in liver in vivo. The results also suggested that the formation of Cr(V) was not the only mechanism involved in the induction of hepatotoxicity by Cr(VI) compounds."
1234577,Comber et al. 1995,Assessment of the toxicity to algae of colored substances,,Assessment of the toxicity to algae of colored substances Abs: 
1234576,Pedraza-Chaverrí et al. 1995,Urinary angiotensin I-converting enzyme activity is increased in experimental acute renal failure,"The angiotensin I-converting enzyme (ACE) activity was studied in 2 experimental models of acute renal failure: (a) rats treated with a single injection of mercuric chloride (1.5 mg/kg) and (b) rats treated with a single injection of potassium dichromate (15 mg/kg). Rats were sacrificed 24 and 48 h after mercuric chloride or potassium dichromate injection. ACE activity was measured in urine, serum, and kidney. These data were compared with vehicle-treated rats. Rats with acute renal failure had proteinuria, polyuria, and decreased creatinine clearance. The damage to the kidney proximal tubule was evident by (a) the histological analysis at light and electron microscopy, (b) the augmentation in the urinary excretion of dipeptidyl aminopeptidase IV and N-acetyl-beta-D-glucosaminidase, and (c) the low molecular weight proteinuria pattern. In addition, the histological analysis at the ultrastructural level showed normal glomeruli appearance. The above data suggest that the increased urinary excretion of enzymes and proteins in rats with acute renal failure is a consequence of tubular injury. Urinary and serum ACE activities increased and kidney ACE activity decreased. Our data suggest that the increase in urine ACE activity may be due to the kidney proximal tubule damage. This work supports the contention that an increase in urine ACE may be an indicator of injury to the proximal tubule.","Urinary angiotensin I-converting enzyme activity is increased in experimental acute renal failure Abs: The angiotensin I-converting enzyme (ACE) activity was studied in 2 experimental models of acute renal failure: (a) rats treated with a single injection of mercuric chloride (1.5 mg/kg) and (b) rats treated with a single injection of potassium dichromate (15 mg/kg). Rats were sacrificed 24 and 48 h after mercuric chloride or potassium dichromate injection. ACE activity was measured in urine, serum, and kidney. These data were compared with vehicle-treated rats. Rats with acute renal failure had proteinuria, polyuria, and decreased creatinine clearance. The damage to the kidney proximal tubule was evident by (a) the histological analysis at light and electron microscopy, (b) the augmentation in the urinary excretion of dipeptidyl aminopeptidase IV and N-acetyl-beta-D-glucosaminidase, and (c) the low molecular weight proteinuria pattern. In addition, the histological analysis at the ultrastructural level showed normal glomeruli appearance. The above data suggest that the increased urinary excretion of enzymes and proteins in rats with acute renal failure is a consequence of tubular injury. Urinary and serum ACE activities increased and kidney ACE activity decreased. Our data suggest that the increase in urine ACE activity may be due to the kidney proximal tubule damage. This work supports the contention that an increase in urine ACE may be an indicator of injury to the proximal tubule."
1234575,Ross and  Brancaccio 1996,Allergic contact dermatitis to tefillin,,Allergic contact dermatitis to tefillin Abs: 
1234574,Dali and  Carstensen 1996,Effect of change in shape factor of a single crystal on its dissolution behavior,"<strong>PURPOSE: </strong>To study the effect of change in the shape factor of real crystals on their dissolution behavior using a potassium dichromate crystal as a model for particulates in general.<br /><br /><strong>METHODS: </strong>A model geometry (parallelepiped) has been suggested for a dissolving particle. Single crystals of potassium dichromate which are monoclinic prisms were grown individually from supersaturated solutions at 40 degrees C. Dissolution studies were carried out on five such crystals in 0.1N H2SO4 at 25 degrees C and a stirrer speed of 50 +/- 1 rpm. The five crystals had different degrees of non-isometricity. Initial dimensions of the crystals were measured using image analysis techniques. The shape factor of the dissolving crystal as a function of time was obtained indirectly from the dissolution data.<br /><br /><strong>RESULTS: </strong>The shape factor of a single crystal changed significantly after about 50% dissolution. The nature of this change depended on the degree of non-isometricity of the crystal. The change in shape factor of the dissolving crystal was accounted for in the Hixson-Crowell cube root law, and a modified form of the cube root equation was developed. This equation for dissolution explained the observed upward curvature in the cube root law plot.<br /><br /><strong>CONCLUSIONS: </strong>The shape factor for any non-isometric particle cannot be considered to be constant over the dissolution event, as is commonly assumed. This change has an appreciable effect on the dissolution behavior of crystals. This study is particularly of significance for elongated shapes like needles and platelets. By the methodology described here, it was possible to determine the initial shape factor of the crystal and the intrinsic dissolution rate constant.","Effect of change in shape factor of a single crystal on its dissolution behavior Abs: <strong>PURPOSE: </strong>To study the effect of change in the shape factor of real crystals on their dissolution behavior using a potassium dichromate crystal as a model for particulates in general.<br /><br /><strong>METHODS: </strong>A model geometry (parallelepiped) has been suggested for a dissolving particle. Single crystals of potassium dichromate which are monoclinic prisms were grown individually from supersaturated solutions at 40 degrees C. Dissolution studies were carried out on five such crystals in 0.1N H2SO4 at 25 degrees C and a stirrer speed of 50 +/- 1 rpm. The five crystals had different degrees of non-isometricity. Initial dimensions of the crystals were measured using image analysis techniques. The shape factor of the dissolving crystal as a function of time was obtained indirectly from the dissolution data.<br /><br /><strong>RESULTS: </strong>The shape factor of a single crystal changed significantly after about 50% dissolution. The nature of this change depended on the degree of non-isometricity of the crystal. The change in shape factor of the dissolving crystal was accounted for in the Hixson-Crowell cube root law, and a modified form of the cube root equation was developed. This equation for dissolution explained the observed upward curvature in the cube root law plot.<br /><br /><strong>CONCLUSIONS: </strong>The shape factor for any non-isometric particle cannot be considered to be constant over the dissolution event, as is commonly assumed. This change has an appreciable effect on the dissolution behavior of crystals. This study is particularly of significance for elongated shapes like needles and platelets. By the methodology described here, it was possible to determine the initial shape factor of the crystal and the intrinsic dissolution rate constant."
1234572,Sarkar et al. 1996,Clastogenic activity of pure chlorophyll and anticlastogenic effects of equivalent amounts of crude extract of Indian spinach leaf and chlorophyllin following dietary supplementation to mice,"Dietary consumption of green vegetables has been associated with protection against mutagenic and clastogenic activity of genotoxicants. Chlorophyll, being present in all green plants, had earlier been suggested to be the principal factor involved. Mice were administered (i) crude aqueous extract of leaf of Indian spinach, Beta vulgaris L. var.benghalensis Hort., and equivalent amounts of (ii) chlorophyll extracted from the leaf; (iii) purified chlorophyll, (iv) chlorophyllin, a sodium-copper derivative of chlorophyll; daily for 7 days. On day 7, one set of mice from each treatment was administered potassium dichromate-a known metallic clastogen. The mice were sacrificed after 24 hours. Chromosome preparations were made from bone marrow following the usual colchicine-air dry-Giemsa schedule. The cytogenetic endpoints scored were chromosomal aberrations and damaged cells. Crude leaf extract and chlorophyllin were nonclastogenic and reduced the clastogenic effects of potassium dichromate to the control distilled water level. Chlorophyll alone, whether extracted from the leaf or obtained in commercially purified form, was clastogenic and could reduce the effects of the chromium salt only to its own level. The protective action of the crude leaf extract may be attributed to the total effect of the interaction between the different components within the leaf extract, in which the clastogenicity of chlorophyll had been neutralized.","Clastogenic activity of pure chlorophyll and anticlastogenic effects of equivalent amounts of crude extract of Indian spinach leaf and chlorophyllin following dietary supplementation to mice Abs: Dietary consumption of green vegetables has been associated with protection against mutagenic and clastogenic activity of genotoxicants. Chlorophyll, being present in all green plants, had earlier been suggested to be the principal factor involved. Mice were administered (i) crude aqueous extract of leaf of Indian spinach, Beta vulgaris L. var.benghalensis Hort., and equivalent amounts of (ii) chlorophyll extracted from the leaf; (iii) purified chlorophyll, (iv) chlorophyllin, a sodium-copper derivative of chlorophyll; daily for 7 days. On day 7, one set of mice from each treatment was administered potassium dichromate-a known metallic clastogen. The mice were sacrificed after 24 hours. Chromosome preparations were made from bone marrow following the usual colchicine-air dry-Giemsa schedule. The cytogenetic endpoints scored were chromosomal aberrations and damaged cells. Crude leaf extract and chlorophyllin were nonclastogenic and reduced the clastogenic effects of potassium dichromate to the control distilled water level. Chlorophyll alone, whether extracted from the leaf or obtained in commercially purified form, was clastogenic and could reduce the effects of the chromium salt only to its own level. The protective action of the crude leaf extract may be attributed to the total effect of the interaction between the different components within the leaf extract, in which the clastogenicity of chlorophyll had been neutralized."
1234571,Bangha and  Elsner 1996,Sensitizations to allergens of the European standard series at the Department of Dermatology in Zurich 1990-1994,"<strong>BACKGROUND: </strong>For planning and evaluation of preventive activities against contact dermatitis, it is important to detect trends in contact sensitization.<br /><br /><strong>OBJECTIVE AND METHODS: </strong>We performed a computer-aided analysis of the patch test results of 5,565 patients tested with the European standard allergens consecutively from 1990 to 1994 in our patch test clinic.<br /><br /><strong>RESULTS: </strong>The male/female ratio was 42.4/ 57.6%. Sixty-one percent of the patients were &lt; 45 years. Hands, face and lower legs were the major localizations of eczema. The largest occupational groups were office workers (21%), houseworkers and cleaning personnel (18%) and pensioners (10%). The highest sensitization rates were found for nickel (18.5%) and fragrance mix (9.6%). An increase of sensitizations to fragrance mix and balsam of Peru in both sexes and a decrease in nickel and cobalt sensitizations for females and potassium dichromate reactions for males were observed.<br /><br /><strong>CONCLUSION: </strong>Our data show considerable changes in the frequency of contact sensitizations that warrant further analytic studies.","Sensitizations to allergens of the European standard series at the Department of Dermatology in Zurich 1990-1994 Abs: <strong>BACKGROUND: </strong>For planning and evaluation of preventive activities against contact dermatitis, it is important to detect trends in contact sensitization.<br /><br /><strong>OBJECTIVE AND METHODS: </strong>We performed a computer-aided analysis of the patch test results of 5,565 patients tested with the European standard allergens consecutively from 1990 to 1994 in our patch test clinic.<br /><br /><strong>RESULTS: </strong>The male/female ratio was 42.4/ 57.6%. Sixty-one percent of the patients were &lt; 45 years. Hands, face and lower legs were the major localizations of eczema. The largest occupational groups were office workers (21%), houseworkers and cleaning personnel (18%) and pensioners (10%). The highest sensitization rates were found for nickel (18.5%) and fragrance mix (9.6%). An increase of sensitizations to fragrance mix and balsam of Peru in both sexes and a decrease in nickel and cobalt sensitizations for females and potassium dichromate reactions for males were observed.<br /><br /><strong>CONCLUSION: </strong>Our data show considerable changes in the frequency of contact sensitizations that warrant further analytic studies."
1234570,Susa et al. 1996,Protective effect of vitamin E on chromium (VI)-induced cytotoxicity and lipid peroxidation in primary cultures of rat hepatocytes,"Pretreatment of primary cultures of rat hepatocytes with alpha-tocopherol succinate (vitamin E) for 20 h prior to exposure to K2Cr2O7 resulted in a marked decrease of chromium (VI)-induced cytotoxicity, as evaluated by the leakage of lactate dehydrogenase, without affecting cellular uptake and the subcellular distribution of chromium. The levels of chromium (VI)-induced lipid peroxidation, as monitored by malondialdehyde formation, were also inhibited by pretreatment with the vitamin. Pretreatment with vitamin E normalized the levels of nonenzymatic antioxidants such as glutathione and vitamin C suppressed by dichromate, and caused a distinct accumulation of vitamin E in hepatocytes. However, vitamin E pretreatment did not affect the activities of enzymatic antioxidants including glutathione reductase, superoxide dismutase, and catalase suppressed by dichromate. These results indicate that the protective effect of vitamin E against chromium (VI)-induced cytotoxicity as well as lipid peroxidation, may be associated more with the level of nonenzymatic antioxidants than the activity of enzymatic antioxidants.","Protective effect of vitamin E on chromium (VI)-induced cytotoxicity and lipid peroxidation in primary cultures of rat hepatocytes Abs: Pretreatment of primary cultures of rat hepatocytes with alpha-tocopherol succinate (vitamin E) for 20 h prior to exposure to K2Cr2O7 resulted in a marked decrease of chromium (VI)-induced cytotoxicity, as evaluated by the leakage of lactate dehydrogenase, without affecting cellular uptake and the subcellular distribution of chromium. The levels of chromium (VI)-induced lipid peroxidation, as monitored by malondialdehyde formation, were also inhibited by pretreatment with the vitamin. Pretreatment with vitamin E normalized the levels of nonenzymatic antioxidants such as glutathione and vitamin C suppressed by dichromate, and caused a distinct accumulation of vitamin E in hepatocytes. However, vitamin E pretreatment did not affect the activities of enzymatic antioxidants including glutathione reductase, superoxide dismutase, and catalase suppressed by dichromate. These results indicate that the protective effect of vitamin E against chromium (VI)-induced cytotoxicity as well as lipid peroxidation, may be associated more with the level of nonenzymatic antioxidants than the activity of enzymatic antioxidants."
1234567,Yang et al. 1996,Infectivity of preserved Cryptosporidium parvum oocysts for immunosuppressed adult mice,"The present study was undertaken to determine the infectivity of Cryptosporidium parvum oocysts for immunosuppressed adult C57BL/6N mice after the oocysts had been stored from 1-48 months at 4 degrees C in 2.5% potassium dichromate. All mice inoculated with oocysts 1-18 months old developed patent infections, while mice inoculated with older oocysts remained uninfected. The prepatent period was extended from 2 to 6 or 7 days as the storage time for oocysts increased. The finding that C. parvum oocysts remain infective for mice for at least 18 months offers important economic and time-saving advantages for investigators who frequently require large numbers of oocysts that must be painstakingly purified from calf manure.","Infectivity of preserved Cryptosporidium parvum oocysts for immunosuppressed adult mice Abs: The present study was undertaken to determine the infectivity of Cryptosporidium parvum oocysts for immunosuppressed adult C57BL/6N mice after the oocysts had been stored from 1-48 months at 4 degrees C in 2.5% potassium dichromate. All mice inoculated with oocysts 1-18 months old developed patent infections, while mice inoculated with older oocysts remained uninfected. The prepatent period was extended from 2 to 6 or 7 days as the storage time for oocysts increased. The finding that C. parvum oocysts remain infective for mice for at least 18 months offers important economic and time-saving advantages for investigators who frequently require large numbers of oocysts that must be painstakingly purified from calf manure."
1234566,Junaid et al. 1996,Embryotoxicity of orally administered chromium in mice: exposure during the period of organogenesis,"Administration of chromium (VI)(250, 500 and 750 ppm as potassium dichromate) via drinking water during organogenesis (days 6-14 of gestation) in mice revealed embryo- and fetotoxic effects. Reduced fetal weight, retarded fetal development, number of fetuses (live and dead) per mother and high incidences of dead fetuses and resorptions in treated mothers in the highest dosed group were evident. No significant gross structural abnormalities were observed in any of the fetuses of chromium (VI)-treated mothers. Significant incidences of reduced ossification were found in the highest dosed group. Chromium levels were increased in a dose-dependent manner in maternal blood, placenta and fetuses. The present study suggests a risk to the developing embryo if the mother is exposed to a sufficiently high concentration of chromium (VI) through drinking water during the period of organogenesis.","Embryotoxicity of orally administered chromium in mice: exposure during the period of organogenesis Abs: Administration of chromium (VI)(250, 500 and 750 ppm as potassium dichromate) via drinking water during organogenesis (days 6-14 of gestation) in mice revealed embryo- and fetotoxic effects. Reduced fetal weight, retarded fetal development, number of fetuses (live and dead) per mother and high incidences of dead fetuses and resorptions in treated mothers in the highest dosed group were evident. No significant gross structural abnormalities were observed in any of the fetuses of chromium (VI)-treated mothers. Significant incidences of reduced ossification were found in the highest dosed group. Chromium levels were increased in a dose-dependent manner in maternal blood, placenta and fetuses. The present study suggests a risk to the developing embryo if the mother is exposed to a sufficiently high concentration of chromium (VI) through drinking water during the period of organogenesis."
1234565,Kranke and  Aberer 1996,Multiple sensitivities to metals,,Multiple sensitivities to metals Abs: 
1234564,Gajdosova and  Reichrtova 1996,"Different growth response of Euglena gracilis to Hg, Cd, Cr and Ni compounds","The toxicity of inorganic mercury, nickel, chromium and cadmium on the unicellular photosynthetic flagellate Euglena gracilis, strain Z (E.g.) has been tested. Under the conditions used each metal impaired the growth rate of E.g., and had a very strong effect on cell motility. The degree of cytotoxicity and motility decreased from mercury iodide to cadmium chloride to cadmium nitrate to potassium dichromate to nickel sulfate. No mutagenic effects of the metals investigated have been observed. Adverse effects of metal compounds can be tested on the eukaryotic species of Euglena gracilis used as an intermediate model system between bacterial and animal model.","Different growth response of Euglena gracilis to Hg, Cd, Cr and Ni compounds Abs: The toxicity of inorganic mercury, nickel, chromium and cadmium on the unicellular photosynthetic flagellate Euglena gracilis, strain Z (E.g.) has been tested. Under the conditions used each metal impaired the growth rate of E.g., and had a very strong effect on cell motility. The degree of cytotoxicity and motility decreased from mercury iodide to cadmium chloride to cadmium nitrate to potassium dichromate to nickel sulfate. No mutagenic effects of the metals investigated have been observed. Adverse effects of metal compounds can be tested on the eukaryotic species of Euglena gracilis used as an intermediate model system between bacterial and animal model."
1234563,Marcusson 1996,"Contact allergies to nickel sulfate, gold sodium thiosulfate and palladium chloride in patients claiming side-effects from dental alloy components","397 patients claiming various subjective symptoms related to dental restoration materials have been tested for the presence of metal allergy. The resultant data have been compared with the corresponding allergies of eczematous patients. The frequency difference of metal allergy in the dental group is statistically significant or close to significance for nickel sulfate, potassium dichromate, cobalt chloride, palladium chloride and gold sodium thiosulfate. The findings suggest that the dental patient group represents a subgroup with a high frequency of metal allergy.","Contact allergies to nickel sulfate, gold sodium thiosulfate and palladium chloride in patients claiming side-effects from dental alloy components Abs: 397 patients claiming various subjective symptoms related to dental restoration materials have been tested for the presence of metal allergy. The resultant data have been compared with the corresponding allergies of eczematous patients. The frequency difference of metal allergy in the dental group is statistically significant or close to significance for nickel sulfate, potassium dichromate, cobalt chloride, palladium chloride and gold sodium thiosulfate. The findings suggest that the dental patient group represents a subgroup with a high frequency of metal allergy."
1234561,Burguera et al. 1996,Head-space flow injection for the on-line determination of iodide in urine samples with chemiluminescence detection,"A simple head-space (HS) flow injection (FI) system with chemiluminescence (CL) detection for the determination of iodide as iodine in urine is presented. The iodide is converted to iodine by potassium dichromate under stirring in the closed HS vial, and the iodine is released from urine by thermostatting and is carried in a nitrogen flow through an iodide trapping solution. The concomitant introduction of aliquots of iodine, luminol and cobalt(II) solutions by means of a time-based injector into an FI system allowed its mixing in a flow-through cell in front of the detector. The emission intensity at 425 nm was recorded as a function of time. The salting-out of the standard solutions affected the gas-liquid distribution coefficient of iodine in the HS vial. The typical analytical working graphs obtained under the optimized experimental conditions were rectilinear from 0 to 5 mg l(-1) iodine, achieving a precision of 2.3 and a relative standard deviation of 1.8 for ten replicate analyses of 50 and 200 microg l(-1) iodine. However, a second-order process becomes significant at higher iodine concentrations (from 10 to 40 mg l(-1)). The detection limit of the method is 10 microg l(-1) (80 ng) iodine when 8 ml samples are taken. Data for the iodide content of 10 urine samples were in good agreement with those obtained by a conventional catalytic method, and recoveries varied between 101 and 103% for urine samples spiked with different amounts of iodide. The analysis of one sample takes less than 20 min. In the present study the iodide levels found for 100 subjects were 86.8 +/- 19.0 (61-125) microg l(-1), which is lower than the WHO's optimal level (150-300 microg per day).","Head-space flow injection for the on-line determination of iodide in urine samples with chemiluminescence detection Abs: A simple head-space (HS) flow injection (FI) system with chemiluminescence (CL) detection for the determination of iodide as iodine in urine is presented. The iodide is converted to iodine by potassium dichromate under stirring in the closed HS vial, and the iodine is released from urine by thermostatting and is carried in a nitrogen flow through an iodide trapping solution. The concomitant introduction of aliquots of iodine, luminol and cobalt(II) solutions by means of a time-based injector into an FI system allowed its mixing in a flow-through cell in front of the detector. The emission intensity at 425 nm was recorded as a function of time. The salting-out of the standard solutions affected the gas-liquid distribution coefficient of iodine in the HS vial. The typical analytical working graphs obtained under the optimized experimental conditions were rectilinear from 0 to 5 mg l(-1) iodine, achieving a precision of 2.3 and a relative standard deviation of 1.8 for ten replicate analyses of 50 and 200 microg l(-1) iodine. However, a second-order process becomes significant at higher iodine concentrations (from 10 to 40 mg l(-1)). The detection limit of the method is 10 microg l(-1) (80 ng) iodine when 8 ml samples are taken. Data for the iodide content of 10 urine samples were in good agreement with those obtained by a conventional catalytic method, and recoveries varied between 101 and 103% for urine samples spiked with different amounts of iodide. The analysis of one sample takes less than 20 min. In the present study the iodide levels found for 100 subjects were 86.8 +/- 19.0 (61-125) microg l(-1), which is lower than the WHO's optimal level (150-300 microg per day)."
1234560,Al-Sheikh and  Gad el-Rab 1996,"Allergic contact dermatitis: clinical features and profile of sensitizing allergens in Riyadh, Saudi Arabia","<strong>BACKGROUND: </strong>No reports are available on allergic contact dermatitis in Saudi Arabia, although it seems to be a common skin problem. We attempted to explore certain clinical aspects in addition to the profile of sensitizing allergens in our area. As no standard panel for patch testing is available in our geographic region, we examined the suitability of the European Standard Series.<br /><br /><strong>METHODS: </strong>Patch testing was performed on 271 consecutive patients with various forms of dermititis, referred for evaluation of possible allergic contact dermatitis. The study included 147 women and 124 men. The patients were between 12 and 75 years of age.<br /><br /><strong>RESULTS: </strong>Out of 271 subjects, 152 (56.1%) showed one or more positive reactions. Of these, 80 (52.6%) were women and 72 (47.4%) were men. Almost one quarter of the patients (25.7%) presented with hand dermatitis. Positive reactions to 21 out of the 22 allergens were found. Sensitization was most common to nickel sulfate (39.5%), potassium dichromate (32.9%), and cobalt chloride (30.9%). Reactions to the other allergens ranged between 14.5% and 1.3%). Less than one percent of the patients (0.66%) reacted to benzocaine and showed no reaction to primin.<br /><br /><strong>CONCLUSIONS: </strong>Allergic contact dermatitis is a common skin problem in Saudi Arabia. Further studies that address the prevalence and incidence of the disease are indicated. The European Standard Series is suitable for patch testing patients in our community; however, we suggest exclusion of benzocaine and primin. The addition of three allergens of local relevance, black seed oil, local perfume mix, and henna, are presented and discussed. The formulation of a regional standard series for patch testing dermatitis patients in our geographic area requires further collaborative studies.","Allergic contact dermatitis: clinical features and profile of sensitizing allergens in Riyadh, Saudi Arabia Abs: <strong>BACKGROUND: </strong>No reports are available on allergic contact dermatitis in Saudi Arabia, although it seems to be a common skin problem. We attempted to explore certain clinical aspects in addition to the profile of sensitizing allergens in our area. As no standard panel for patch testing is available in our geographic region, we examined the suitability of the European Standard Series.<br /><br /><strong>METHODS: </strong>Patch testing was performed on 271 consecutive patients with various forms of dermititis, referred for evaluation of possible allergic contact dermatitis. The study included 147 women and 124 men. The patients were between 12 and 75 years of age.<br /><br /><strong>RESULTS: </strong>Out of 271 subjects, 152 (56.1%) showed one or more positive reactions. Of these, 80 (52.6%) were women and 72 (47.4%) were men. Almost one quarter of the patients (25.7%) presented with hand dermatitis. Positive reactions to 21 out of the 22 allergens were found. Sensitization was most common to nickel sulfate (39.5%), potassium dichromate (32.9%), and cobalt chloride (30.9%). Reactions to the other allergens ranged between 14.5% and 1.3%). Less than one percent of the patients (0.66%) reacted to benzocaine and showed no reaction to primin.<br /><br /><strong>CONCLUSIONS: </strong>Allergic contact dermatitis is a common skin problem in Saudi Arabia. Further studies that address the prevalence and incidence of the disease are indicated. The European Standard Series is suitable for patch testing patients in our community; however, we suggest exclusion of benzocaine and primin. The addition of three allergens of local relevance, black seed oil, local perfume mix, and henna, are presented and discussed. The formulation of a regional standard series for patch testing dermatitis patients in our geographic area requires further collaborative studies."
1234558,Adams et al. 1996,Detection of DNA damage induced by human carcinogens in acellular assays: potential application for determining genotoxic mechanisms,"Positive outcomes of in vitro genotoxicity tests may not always occur as a consequence of direct reaction of a compound or a metabolite with DNA. To follow-up positive responses in in vitro tests, we developed two supplemental, cell-free assays to examine the potential of compounds and metabolites to directly damage DNA. Calf thymus DNA was used as the target for the direct detection of adducts by 32P-postlabeling/TLC and electrochemical detection, and alkaline gel electrophoresis was used to detect single-strand breakage of bacteriophage lambda DNA. To show that these assays would detect damage from relevant compounds, we examined nine human carcinogens (aflatoxin B1, busulfan, chlorambucil, cyclophosphamide, diethylstilbestrol, melphalan, 2-naphthylamine, phenacetin and potassium chromate). Each of the nine compounds produced a positive result for one or both endpoints. Using multifraction contact-transfer TLC, we detected 32P-labeled DNA adducts produced by aflatoxin B1, chlorambucil, diethylstilbestrol, melphalan, 2-naphthylamine, and potassium chromate (plus hydrogen peroxide). Aflatoxin B1, diethylstilbestrol and 2-naphthylamine required metabolic activation (induced rat liver S9) to generate DNA adducts. Although potassium chromate alone induced a slight increase in the content of 8-hydroxydeoxyguanosine (a promutagenic adduct produced by reactive oxygen species), addition of hydrogen peroxide greatly increased 8-hydroxydeoxyguanosine levels. The damage to lambda DNA by each human carcinogen (or metabolites), except diethylstilbestrol, was sufficient to generate single-strand breaks after neutral thermal hydrolysis at 70 degrees C. Chromate was a weak inducer of DNA fragmentation, but adding hydrogen peroxide to the reaction mixtures dramatically increased the DNA strand breakage. Our data suggest that these non-routine, acellular tests for determining direct DNA damage may provide valuable mechanistic insight for positive responses in cell-based genetic toxicology tests.","Detection of DNA damage induced by human carcinogens in acellular assays: potential application for determining genotoxic mechanisms Abs: Positive outcomes of in vitro genotoxicity tests may not always occur as a consequence of direct reaction of a compound or a metabolite with DNA. To follow-up positive responses in in vitro tests, we developed two supplemental, cell-free assays to examine the potential of compounds and metabolites to directly damage DNA. Calf thymus DNA was used as the target for the direct detection of adducts by 32P-postlabeling/TLC and electrochemical detection, and alkaline gel electrophoresis was used to detect single-strand breakage of bacteriophage lambda DNA. To show that these assays would detect damage from relevant compounds, we examined nine human carcinogens (aflatoxin B1, busulfan, chlorambucil, cyclophosphamide, diethylstilbestrol, melphalan, 2-naphthylamine, phenacetin and potassium chromate). Each of the nine compounds produced a positive result for one or both endpoints. Using multifraction contact-transfer TLC, we detected 32P-labeled DNA adducts produced by aflatoxin B1, chlorambucil, diethylstilbestrol, melphalan, 2-naphthylamine, and potassium chromate (plus hydrogen peroxide). Aflatoxin B1, diethylstilbestrol and 2-naphthylamine required metabolic activation (induced rat liver S9) to generate DNA adducts. Although potassium chromate alone induced a slight increase in the content of 8-hydroxydeoxyguanosine (a promutagenic adduct produced by reactive oxygen species), addition of hydrogen peroxide greatly increased 8-hydroxydeoxyguanosine levels. The damage to lambda DNA by each human carcinogen (or metabolites), except diethylstilbestrol, was sufficient to generate single-strand breaks after neutral thermal hydrolysis at 70 degrees C. Chromate was a weak inducer of DNA fragmentation, but adding hydrogen peroxide to the reaction mixtures dramatically increased the DNA strand breakage. Our data suggest that these non-routine, acellular tests for determining direct DNA damage may provide valuable mechanistic insight for positive responses in cell-based genetic toxicology tests."
1234557,Wilkowska et al. 1996,Contact allergy in children,"With a view to determining the frequency of contact allergy in children, a group of 100 subjects 5 to 15 years of age with various dermatoses was examined. The study group included children with allergic dermatoses (atopic dermatitis, eczema, and others) as well as nonallergic skin diseases (alopecia areata, psoriasis, vitiligo). The frequency of contact allergy occurrence in the individual groups has been determined. Contact allergy occurred the most frequently in children with various forms of eczema (60 percent), the least frequently in those with nonallergic dermatoses (32 percent). Children with eczema most often displayed a polyvalent allergy. Most frequently, positive patch test reactions occurred with potassium dichromate (in 21 percent of children), with cobalt chloride (in 11 percent), and with neomycin sulfate (in 10 percent).","Contact allergy in children Abs: With a view to determining the frequency of contact allergy in children, a group of 100 subjects 5 to 15 years of age with various dermatoses was examined. The study group included children with allergic dermatoses (atopic dermatitis, eczema, and others) as well as nonallergic skin diseases (alopecia areata, psoriasis, vitiligo). The frequency of contact allergy occurrence in the individual groups has been determined. Contact allergy occurred the most frequently in children with various forms of eczema (60 percent), the least frequently in those with nonallergic dermatoses (32 percent). Children with eczema most often displayed a polyvalent allergy. Most frequently, positive patch test reactions occurred with potassium dichromate (in 21 percent of children), with cobalt chloride (in 11 percent), and with neomycin sulfate (in 10 percent)."
1234556,Koppen and  Verschaeve 1996,The alkaline comet test on plant cells: a new genotoxicity test for DNA strand breaks in Vicia faba root cells,"The alkaline comet assay (single cell gel electrophoresis assay) is a sensitive method for the detection of DNA damage. This paper describes the first application of this assay to plant cells for genotoxicological assessment. Germinating Vicia faba (field bean) seedlings were kept in water with either methyl methanesulfonate (MMS), ethyl methanesulfonate (EMS), mitomycin C (MMC), cycloheximide (CH), cadmium chloride (CdCl2), potassium dichromate (K2Cr2O7), or chromium trichloride (CrCl3). Nuclei were isolated from the root cells and evaluated for the extent of DNA migration. With the exception of cycloheximide, all agents induced a significant increase in DNA migration. These results indicate that the comet assay may be a valuable tool for monitoring DNA damage in plant systems. However, there was a significant heterogeneity in the extent of DNA migration within and between seedlings, which may be intrinsic to the assay or indicative of sampling problems.","The alkaline comet test on plant cells: a new genotoxicity test for DNA strand breaks in Vicia faba root cells Abs: The alkaline comet assay (single cell gel electrophoresis assay) is a sensitive method for the detection of DNA damage. This paper describes the first application of this assay to plant cells for genotoxicological assessment. Germinating Vicia faba (field bean) seedlings were kept in water with either methyl methanesulfonate (MMS), ethyl methanesulfonate (EMS), mitomycin C (MMC), cycloheximide (CH), cadmium chloride (CdCl2), potassium dichromate (K2Cr2O7), or chromium trichloride (CrCl3). Nuclei were isolated from the root cells and evaluated for the extent of DNA migration. With the exception of cycloheximide, all agents induced a significant increase in DNA migration. These results indicate that the comet assay may be a valuable tool for monitoring DNA damage in plant systems. However, there was a significant heterogeneity in the extent of DNA migration within and between seedlings, which may be intrinsic to the assay or indicative of sampling problems."
1234555,Thaker et al. 1996,"Effects of chromium(VI) on some ion-dependent ATPases in gills, kidney and intestine of a coastal teleost Periophthalmus dipes","The coastal teleost species, Periophthalmus dipes, commonly known as the mudskipper, was exposed to three sublethal concentrations (5, 10 and 15 mg/l) of potassium chromate for three exposure durations (2, 4 and 6 days). The study compares the dose- and duration-dependent effects of Cr(VI), as potassium chromate, on the ATPase systems in various organs of this fish species. In this study, effects of Cr(VI) stress on total ATPase, (Na+,K+)-ATPase, (Ca+2)-ATPase, (Mg+2)-ATPase, (Ca+2, HCO3-)-ATPase and (Mg+2,HCO3-)-ATPase in gills, kidney and intestine were estimated. A general dose- and duration-dependent inhibitory trend was observed. However, it is evident that exposure duration is more important then dose in the inhibition of the activity of the enzymes. At some concentrations, initial stimulation of the activity of some enzymes were also noticed. However, maximum inhibition was observed in higher Cr(VI) concentrations exposed for the longest time. It is possible that this inhibition of the ATPases by Cr(VI) blocked the active transport system of the gill epithelial as well as chloride cells, glomerular and epithelial cells of the tubules and thus altered the osmoregulatory mechanism of the fish. It appears that this heavy metal ion alters the membrane permeability of the intestinal epithelial cells and other layer of cells by altering the activity of ATPases, resulting in a breakdown of the active transport mechanism needed for the absorption of nutrients, ions and metabolites.","Effects of chromium(VI) on some ion-dependent ATPases in gills, kidney and intestine of a coastal teleost Periophthalmus dipes Abs: The coastal teleost species, Periophthalmus dipes, commonly known as the mudskipper, was exposed to three sublethal concentrations (5, 10 and 15 mg/l) of potassium chromate for three exposure durations (2, 4 and 6 days). The study compares the dose- and duration-dependent effects of Cr(VI), as potassium chromate, on the ATPase systems in various organs of this fish species. In this study, effects of Cr(VI) stress on total ATPase, (Na+,K+)-ATPase, (Ca+2)-ATPase, (Mg+2)-ATPase, (Ca+2, HCO3-)-ATPase and (Mg+2,HCO3-)-ATPase in gills, kidney and intestine were estimated. A general dose- and duration-dependent inhibitory trend was observed. However, it is evident that exposure duration is more important then dose in the inhibition of the activity of the enzymes. At some concentrations, initial stimulation of the activity of some enzymes were also noticed. However, maximum inhibition was observed in higher Cr(VI) concentrations exposed for the longest time. It is possible that this inhibition of the ATPases by Cr(VI) blocked the active transport system of the gill epithelial as well as chloride cells, glomerular and epithelial cells of the tubules and thus altered the osmoregulatory mechanism of the fish. It appears that this heavy metal ion alters the membrane permeability of the intestinal epithelial cells and other layer of cells by altering the activity of ATPases, resulting in a breakdown of the active transport mechanism needed for the absorption of nutrients, ions and metabolites."
1234554,Gfesser et al. 1996,The disturbance of epidermal barrier function in atopy patch test reactions in atopic eczema,"Atopic eczema (AE) is a common skin disorder. Eczematous lesions showing macroscopic, microscopic and immunopathological resemblance to lesional AE can be induced by aeroallergens by epicutaneous testing (atopy patch test, APT). Altered epidermal barrier function, as determined by transepidermal water loss (TEWL), is a typical feature of patients with AE. The present investigation was performed to define the differences in the epidermal barrier function between positive APT reactions to aeroallergens and positive patch test reactions to contact allergens in AE patients. Allergen extracts from grass pollen, birch pollen, cat dander and house dust mite (Dermatophagoides pteronyssinus) were applied in large Finn chambers on Scanpor for 48 h on the clinically unaffected and untreated skin of the back, in 11 patients with AE. The same procedure was done with 27 contact allergens of a standard test battery. Test reactions were read and TEWL was measured after 48 and 72 h. Eight of the 11 patients developed positive APT reactions to D. pteronyssinus, two to cat dander and one to birch pollen. Seven of the 11 patients showed positive patch test reactions to nickel sulphate, two to potassium dichromate, one to thiuram-mix and one to paraphenylenediamine. Vehicle controls were negative. The TEWL of the positive APT reactions was significantly higher, both after 48 h (mean +/- standard deviation 10.0 +/- 6.5 g/m2h) and after 72 h (9.7 +/- 5.4 g/m2h) as compared with the control site (48/72h: 4.4 +/- 1.5/4.1 +/- 1.4 g/m2h) (P &lt; 0.01). In contrast, TEWL of the positive patch test reactions to contact allergens (48/72 h: 5.4 +/- 2.2/5.4 +/- 1.9 g/m2h) was similar to that of the control site (48/72 h: 5.2 +/- 2.1/5.0 +/- 1.8 g/m2h) (not significant). The relative TEWL at 48 h and 72 h, expressed as the ratio between the positive patch test and the control site, was significantly higher in the positive APT reactions (48/72 h: 218.8 +/- 80.4%/232.0 +/- 85.9%) compared with positive patch test reactions to contact allergens (48/72 h: 102.1 +/- 12.0%/107.1 +/- 9.5%) (P &lt; 0.01). It is concluded that the epidermal barrier function in AE patients is altered only in positive APT reactions, in contrast to positive patch test reactions to contact allergens. As a consequence of this aeroallergen-induced altered epidermal barrier function, further allergens can more easily penetrate the skin, inducing a vicious circle and perpetuating the eczematous lesions.","The disturbance of epidermal barrier function in atopy patch test reactions in atopic eczema Abs: Atopic eczema (AE) is a common skin disorder. Eczematous lesions showing macroscopic, microscopic and immunopathological resemblance to lesional AE can be induced by aeroallergens by epicutaneous testing (atopy patch test, APT). Altered epidermal barrier function, as determined by transepidermal water loss (TEWL), is a typical feature of patients with AE. The present investigation was performed to define the differences in the epidermal barrier function between positive APT reactions to aeroallergens and positive patch test reactions to contact allergens in AE patients. Allergen extracts from grass pollen, birch pollen, cat dander and house dust mite (Dermatophagoides pteronyssinus) were applied in large Finn chambers on Scanpor for 48 h on the clinically unaffected and untreated skin of the back, in 11 patients with AE. The same procedure was done with 27 contact allergens of a standard test battery. Test reactions were read and TEWL was measured after 48 and 72 h. Eight of the 11 patients developed positive APT reactions to D. pteronyssinus, two to cat dander and one to birch pollen. Seven of the 11 patients showed positive patch test reactions to nickel sulphate, two to potassium dichromate, one to thiuram-mix and one to paraphenylenediamine. Vehicle controls were negative. The TEWL of the positive APT reactions was significantly higher, both after 48 h (mean +/- standard deviation 10.0 +/- 6.5 g/m2h) and after 72 h (9.7 +/- 5.4 g/m2h) as compared with the control site (48/72h: 4.4 +/- 1.5/4.1 +/- 1.4 g/m2h) (P &lt; 0.01). In contrast, TEWL of the positive patch test reactions to contact allergens (48/72 h: 5.4 +/- 2.2/5.4 +/- 1.9 g/m2h) was similar to that of the control site (48/72 h: 5.2 +/- 2.1/5.0 +/- 1.8 g/m2h) (not significant). The relative TEWL at 48 h and 72 h, expressed as the ratio between the positive patch test and the control site, was significantly higher in the positive APT reactions (48/72 h: 218.8 +/- 80.4%/232.0 +/- 85.9%) compared with positive patch test reactions to contact allergens (48/72 h: 102.1 +/- 12.0%/107.1 +/- 9.5%) (P &lt; 0.01). It is concluded that the epidermal barrier function in AE patients is altered only in positive APT reactions, in contrast to positive patch test reactions to contact allergens. As a consequence of this aeroallergen-induced altered epidermal barrier function, further allergens can more easily penetrate the skin, inducing a vicious circle and perpetuating the eczematous lesions."
1234553,Jonuleit et al. 1996,Specific stabilization of the 4F7 molecule on dendritic cells by contact allergens,"Our laboratory has recently developed the monoclonal antibody 4F7 which recognizes a molecule on dendritic cells in the dermis of mice that is upregulated after application of contact allergens in vivo. Furthermore, this antibody detects an antigen on dendritic cells in spleen, lymph nodes and colon. In order to study the influence of contact allergens on the surface expression of the 4F7 molecules on dendritic cells, FACScan analysis of splenic dendritic cells was carried out after in vitro application of contact allergens. Freshly isolated splenic dendritic cells were found to be positive for 4F7, 33D1, N418 (CD11c) and MHC class II. After overnight culture the expression of the dendritic cell-specific molecules 4F7 and 33D1 was decreased. This downregulation was not inhibited by the addition of the cytokines TNF-alpha or GM-CSF during in vitro culture. However, in vitro treatment of freshly isolated dendritic cells with the contact allergen 2,4-dinitrofluorobenzene prevented this downregulation of the 4F7 surface molecules. The same effect was observed after treatment with other contact allergens (1-chloro-2,4-dinitrobenzene or potassium dichromate). Treatment with the irritant substance sodium dodecyl sulphate, the lectins concanavalin and lipopolysaccharide or the phorbol ester PMA did not prevent the downregulation of 4F7 and 33D1. Moreover, the influence of contact allergens on the expression of the molecules 4F7 and 33D1 was not inhibited by the protein synthesis inhibitor cycloheximide. No effects of contact sensitizers were detectable on the expression of MHC class II molecules or the costimulatory molecules B7 and heat-stable antigen. Our results show a specific stabilizing effect of contact allergens on the dendritic cell-specific molecules 4F7 and 33D1 independent of de novo protein synthesis.","Specific stabilization of the 4F7 molecule on dendritic cells by contact allergens Abs: Our laboratory has recently developed the monoclonal antibody 4F7 which recognizes a molecule on dendritic cells in the dermis of mice that is upregulated after application of contact allergens in vivo. Furthermore, this antibody detects an antigen on dendritic cells in spleen, lymph nodes and colon. In order to study the influence of contact allergens on the surface expression of the 4F7 molecules on dendritic cells, FACScan analysis of splenic dendritic cells was carried out after in vitro application of contact allergens. Freshly isolated splenic dendritic cells were found to be positive for 4F7, 33D1, N418 (CD11c) and MHC class II. After overnight culture the expression of the dendritic cell-specific molecules 4F7 and 33D1 was decreased. This downregulation was not inhibited by the addition of the cytokines TNF-alpha or GM-CSF during in vitro culture. However, in vitro treatment of freshly isolated dendritic cells with the contact allergen 2,4-dinitrofluorobenzene prevented this downregulation of the 4F7 surface molecules. The same effect was observed after treatment with other contact allergens (1-chloro-2,4-dinitrobenzene or potassium dichromate). Treatment with the irritant substance sodium dodecyl sulphate, the lectins concanavalin and lipopolysaccharide or the phorbol ester PMA did not prevent the downregulation of 4F7 and 33D1. Moreover, the influence of contact allergens on the expression of the molecules 4F7 and 33D1 was not inhibited by the protein synthesis inhibitor cycloheximide. No effects of contact sensitizers were detectable on the expression of MHC class II molecules or the costimulatory molecules B7 and heat-stable antigen. Our results show a specific stabilizing effect of contact allergens on the dendritic cell-specific molecules 4F7 and 33D1 independent of de novo protein synthesis."
1234552,Mersch et al. 1996,"Induction of micronuclei in haemocytes and gill cells of zebra mussels, Dreissena polymorpha, exposed to clastogens","Zebra mussels, Dreissena polymorpha, were exposed to four directly acting reference clastogens (mitomycin C, bleomycin, dimethylarsinic acid and potassium chromate) under laboratory conditions. The aim was to examine the inducibility of micronuclei (MN) in haemocytes and gill cells. Positive responses were observed in both tissues for all four substances used under the given test conditions. The mean MN frequencies in treated mussels ranged between 3.2 and 6.9/1000 in haemocytes and between 5.4 and 6.7/1000 in gill cells. The spontaneous MN levels averaged 1.2 and 2.8/1000 in haemocytes and gill cells, respectively. The MN induction capacity of the different chemicals was equivalent in both tissues, except for the treatment with dimethylarsinic acid which generated a significantly higher MN rate in gill cells than in haemocytes. Several characteristics suggest that haemolymph is the more appropriate test tissue for environmental genotoxicity assessment: (1) a shorter preparation time of slides, (2) a more accurate identification of unambiguous MN, (3) a lower baseline MN frequency and a higher induction factor.","Induction of micronuclei in haemocytes and gill cells of zebra mussels, Dreissena polymorpha, exposed to clastogens Abs: Zebra mussels, Dreissena polymorpha, were exposed to four directly acting reference clastogens (mitomycin C, bleomycin, dimethylarsinic acid and potassium chromate) under laboratory conditions. The aim was to examine the inducibility of micronuclei (MN) in haemocytes and gill cells. Positive responses were observed in both tissues for all four substances used under the given test conditions. The mean MN frequencies in treated mussels ranged between 3.2 and 6.9/1000 in haemocytes and between 5.4 and 6.7/1000 in gill cells. The spontaneous MN levels averaged 1.2 and 2.8/1000 in haemocytes and gill cells, respectively. The MN induction capacity of the different chemicals was equivalent in both tissues, except for the treatment with dimethylarsinic acid which generated a significantly higher MN rate in gill cells than in haemocytes. Several characteristics suggest that haemolymph is the more appropriate test tissue for environmental genotoxicity assessment: (1) a shorter preparation time of slides, (2) a more accurate identification of unambiguous MN, (3) a lower baseline MN frequency and a higher induction factor."
1234551,Kansu and  Aydin 1996,Evaluation of the biocompatibility of various dental alloys: Part 2--Allergenical potentials,"The metal alloys which were investigated histopathologically in the first part of this study, were examined with respect to their allergic potentials using the patch test. Results from 60 subjects (aged 17-23) were evaluated following exposure to nickel sulphate, potassium dichromate, silver nitrate, cobalt nitrate, copper sulphate, palladium chloride, platinum chloride and gold chloride. Nickel sulphate produced the most vigorous allergic response whereas gold chloride showed the least of all. The remaining solutions were ranked in decreasing order of severity as follows: potassium dichromate, cobalt nitrate, silver nitrate, copper sulphate, palladium chloride and platinum chloride. Patch testing is indicated in any patient with a history of allergy or sensitivity to a metal. The use of nickel containing alloys in such patients should also be avoided.","Evaluation of the biocompatibility of various dental alloys: Part 2--Allergenical potentials Abs: The metal alloys which were investigated histopathologically in the first part of this study, were examined with respect to their allergic potentials using the patch test. Results from 60 subjects (aged 17-23) were evaluated following exposure to nickel sulphate, potassium dichromate, silver nitrate, cobalt nitrate, copper sulphate, palladium chloride, platinum chloride and gold chloride. Nickel sulphate produced the most vigorous allergic response whereas gold chloride showed the least of all. The remaining solutions were ranked in decreasing order of severity as follows: potassium dichromate, cobalt nitrate, silver nitrate, copper sulphate, palladium chloride and platinum chloride. Patch testing is indicated in any patient with a history of allergy or sensitivity to a metal. The use of nickel containing alloys in such patients should also be avoided."
1234550,Murthy et al. 1996,Ovarian dysfunction in mice following chromium (VI) exposure,"Chromium (VI) was given through drinking water in two sets of adult Swiss albino female mice in three doses; 250 ppm, 500 ppm and 750 ppm for 20 days in set 1 and 0.05 ppm, 0.5 ppm and 5.0 ppm in set II for 90 days. At the termination of the treatment, the animals of both the sets were euthanized for histopathology, follicle counting, counting of the superovulated ova, duration of estrus cycle and for ultrastructural studies. Ovaries of the highest dose group (750 ppm) showed large numbers of atretic follicles and congestion in stromal tissue compared to the rest of the treated groups. Also, there was a dose-dependent reduction in the number of follicles at different stages of their maturation. The number of ova recovered from superovulated chromium (VI)-treated animals showed significant decreases in the 500 and 750 ppm dosed groups compared to lower dosed (250 ppm) and control groups. The duration of estrus cycle increased in highest dosed (750 ppm) group. A dose-dependent increase in blood chromium level was also seen in treated mice. Ultrastructural observations revealed disintegrated cell membranes of two layered follicular cells and altered villiform mitochondria in thecal cells of 5 ppm dosed group. From the study it was concluded that ovarian physiology and rate of ovulation might be altered if females are exposed to sufficiently high chromium through oral route.","Ovarian dysfunction in mice following chromium (VI) exposure Abs: Chromium (VI) was given through drinking water in two sets of adult Swiss albino female mice in three doses; 250 ppm, 500 ppm and 750 ppm for 20 days in set 1 and 0.05 ppm, 0.5 ppm and 5.0 ppm in set II for 90 days. At the termination of the treatment, the animals of both the sets were euthanized for histopathology, follicle counting, counting of the superovulated ova, duration of estrus cycle and for ultrastructural studies. Ovaries of the highest dose group (750 ppm) showed large numbers of atretic follicles and congestion in stromal tissue compared to the rest of the treated groups. Also, there was a dose-dependent reduction in the number of follicles at different stages of their maturation. The number of ova recovered from superovulated chromium (VI)-treated animals showed significant decreases in the 500 and 750 ppm dosed groups compared to lower dosed (250 ppm) and control groups. The duration of estrus cycle increased in highest dosed (750 ppm) group. A dose-dependent increase in blood chromium level was also seen in treated mice. Ultrastructural observations revealed disintegrated cell membranes of two layered follicular cells and altered villiform mitochondria in thecal cells of 5 ppm dosed group. From the study it was concluded that ovarian physiology and rate of ovulation might be altered if females are exposed to sufficiently high chromium through oral route."
1234549,Mattagajasingh and  Misra 1996,Mechanisms of the carcinogenic chromium(VI)-induced DNA-protein cross-linking and their characterization in cultured intact human cells,"DNA-protein complexes (DPCs) were induced in human leukemic T-lymphocyte MOLT4 cells by treatment with potassium chromate. DPCs were isolated by ultracentrifugal sedimentation in the presence of 2% SDS and 5 M urea. The complexes were analyzed by two-dimensional SDS-polyacrylamide gel electrophoresis. Three acidic proteins of 74, 44, and 42 kDa and a basic protein of 51 kDa were primarily complexed to DNA following 25 microM chromate treatment. Higher concentrations of chromate cross-linked many other proteins to DNA. Amino acid sequencing and immunoblotting studies indicated that the acidic 44-kDa protein could be nuclear beta-actin. Lectin and aminoglycoside nucleotidyltransferase were also found to cross-link with DNA by chromate treatment. The composition and stability of the DPCs were studied using nucleases, proteinase K, and disruptive chemicals. Pretreatment of cells with antioxidants inhibited the formation of DPCs, measured as K+-SDS precipitable DPCs, indicating the involvement of oxidative mechanisms. Because chromate causes certain nuclear proteins to form complexes with DNA and the complexes are resistant to treatments such as 2% SDS and 5 M urea, but disruptable under gel electrophoretic conditions, chromium could be used as a cross-linking agent for the identification of other proteins, such as transcription factors, that transiently interact with DNA.","Mechanisms of the carcinogenic chromium(VI)-induced DNA-protein cross-linking and their characterization in cultured intact human cells Abs: DNA-protein complexes (DPCs) were induced in human leukemic T-lymphocyte MOLT4 cells by treatment with potassium chromate. DPCs were isolated by ultracentrifugal sedimentation in the presence of 2% SDS and 5 M urea. The complexes were analyzed by two-dimensional SDS-polyacrylamide gel electrophoresis. Three acidic proteins of 74, 44, and 42 kDa and a basic protein of 51 kDa were primarily complexed to DNA following 25 microM chromate treatment. Higher concentrations of chromate cross-linked many other proteins to DNA. Amino acid sequencing and immunoblotting studies indicated that the acidic 44-kDa protein could be nuclear beta-actin. Lectin and aminoglycoside nucleotidyltransferase were also found to cross-link with DNA by chromate treatment. The composition and stability of the DPCs were studied using nucleases, proteinase K, and disruptive chemicals. Pretreatment of cells with antioxidants inhibited the formation of DPCs, measured as K+-SDS precipitable DPCs, indicating the involvement of oxidative mechanisms. Because chromate causes certain nuclear proteins to form complexes with DNA and the complexes are resistant to treatments such as 2% SDS and 5 M urea, but disruptable under gel electrophoretic conditions, chromium could be used as a cross-linking agent for the identification of other proteins, such as transcription factors, that transiently interact with DNA."
1234548,Kanojia et al. 1996,Chromium induced teratogenicity in female rat,"Exposure to chromium (VI) (250, 500 and 750 ppm as potassium dichromate) via drinking water pregestationally in rats revealed embryo- and fetotoxic effects in the form of a significant reduction in the number of implantations and number of fetuses. An increase in the number of resorptions, pre-implantation and post-implantation loss in chromium (VI)-treated mothers was also observed. No significant visceral abnormality was found. A significant increase in sub-dermal hemorrhagic patches on thoracic and abdominal areas was found. Skeletal abnormality in the form of reduced ossification in parietal, interparietal and caudal bones was found in the fetuses of chromium (VI)-treated mothers. Chromium levels in blood, placenta and fetuses were found to be significantly increased in the 500 ppm and 750 ppm dosed groups. The duration of estrus cycle was significantly altered after chromium (VI) exposure. This study suggests that chromium exposure in rat causes a lower degree of toxicity than in mice as observed in our earlier studies.","Chromium induced teratogenicity in female rat Abs: Exposure to chromium (VI) (250, 500 and 750 ppm as potassium dichromate) via drinking water pregestationally in rats revealed embryo- and fetotoxic effects in the form of a significant reduction in the number of implantations and number of fetuses. An increase in the number of resorptions, pre-implantation and post-implantation loss in chromium (VI)-treated mothers was also observed. No significant visceral abnormality was found. A significant increase in sub-dermal hemorrhagic patches on thoracic and abdominal areas was found. Skeletal abnormality in the form of reduced ossification in parietal, interparietal and caudal bones was found in the fetuses of chromium (VI)-treated mothers. Chromium levels in blood, placenta and fetuses were found to be significantly increased in the 500 ppm and 750 ppm dosed groups. The duration of estrus cycle was significantly altered after chromium (VI) exposure. This study suggests that chromium exposure in rat causes a lower degree of toxicity than in mice as observed in our earlier studies."
1234547,Susa et al. 1997,"Protective effect of deferoxamine on chromium (VI)-induced DNA single-strand breaks, cytotoxicity, and lipid peroxidation in primary cultures of rat hepatocytes","Incubation of primary cultures of rat hepatocytes with K2CR2O7 and deferoxamine (DFO), an iron chelator, resulted in a marked decrease in cellular levels of DNA single-strand breaks caused by K2Cr2O7. Cellular treatment with DFO also suppressed both dichromate-induced cytotoxicity--evaluated by the leakage of lactate dehydrogenase, and lipid peroxidation--as monitored by malondialdehyde formation. In addition, treatment with DFO attenuated the suppression of the levels of vitamin E and C as well as the inhibition of alkaline phosphatase and glutathione peroxidase activity attributed to K2Cr2O7. However, DFO had no influence on the cellular level of glutathione or the activity of glutathione reductase and superoxide dismutase suppressed by dichromate. Under the same experimental conditions, cellular uptake and distribution of chromium were not affected by DFO. These results indicate that DFO protects cells from chromium (VI)-induced DNA strand breaks, cytotoxicity, lipid peroxidation, vitamin E and C depression, and glutathione peroxidase inhibition The role of antioxidants in chromium (VI)-induced cytotoxicity, DNA breaks, and lipid peroxidation is discussed.","Protective effect of deferoxamine on chromium (VI)-induced DNA single-strand breaks, cytotoxicity, and lipid peroxidation in primary cultures of rat hepatocytes Abs: Incubation of primary cultures of rat hepatocytes with K2CR2O7 and deferoxamine (DFO), an iron chelator, resulted in a marked decrease in cellular levels of DNA single-strand breaks caused by K2Cr2O7. Cellular treatment with DFO also suppressed both dichromate-induced cytotoxicity--evaluated by the leakage of lactate dehydrogenase, and lipid peroxidation--as monitored by malondialdehyde formation. In addition, treatment with DFO attenuated the suppression of the levels of vitamin E and C as well as the inhibition of alkaline phosphatase and glutathione peroxidase activity attributed to K2Cr2O7. However, DFO had no influence on the cellular level of glutathione or the activity of glutathione reductase and superoxide dismutase suppressed by dichromate. Under the same experimental conditions, cellular uptake and distribution of chromium were not affected by DFO. These results indicate that DFO protects cells from chromium (VI)-induced DNA strand breaks, cytotoxicity, lipid peroxidation, vitamin E and C depression, and glutathione peroxidase inhibition The role of antioxidants in chromium (VI)-induced cytotoxicity, DNA breaks, and lipid peroxidation is discussed."
1234546,Ockenfels et al. 1997,Contact allergy in patients with periorbital eczema: an analysis of allergens. Data recorded by the Information Network of the Departments of Dermatology,"<strong>BACKGROUND: </strong>Periorbital eczema may be an expression of a constitutional disease or an irritant or allergic dermatitis. An allergic contract dermatitis is believed to be the most common cause.<br /><br /><strong>OBJECTIVE: </strong>We tried to determine which allergens may cause an allergic contact dermatitis and if there exists a leading allergen.<br /><br /><strong>METHODS: </strong>609 patients with periorbital eczema were assessed with patch testing in 22 hospitals to evaluate the relevance of an allergic contact dermatitis in the pathogenesis of periorbital eczema. Additionally, 116 patients were tested with their own products.<br /><br /><strong>RESULTS: </strong>81% of the cases involving the eyelids were women. A relevant allergic contact dermatitis was found in 52% of the patients with periorbital eczema. Furthermore, a positive patch test was present in every third patient with the clinical diagnosis of an atopic dermatitis. Antibiotics, phenylephrine and thimerosal could be determined to be the leading allergens responsible for allergic periorbital eczema. Positive reactions for potassium dichromate and fragrance mix occurred less frequently in patients with periorbital eczema. 132 positive reactions were found in patients tested with their own products, including 33% with a positive reaction to eye ointments, 15% to face creams, 10% to eye shadows, 10% to makeup, 10% to shampoos and 4% to nail varnish. Only 6% reacted to perfume.<br /><br /><strong>CONCLUSION: </strong>The data underline the importance of performing patch tests in the case of periorbital eczema, especially in atopic patients.","Contact allergy in patients with periorbital eczema: an analysis of allergens. Data recorded by the Information Network of the Departments of Dermatology Abs: <strong>BACKGROUND: </strong>Periorbital eczema may be an expression of a constitutional disease or an irritant or allergic dermatitis. An allergic contract dermatitis is believed to be the most common cause.<br /><br /><strong>OBJECTIVE: </strong>We tried to determine which allergens may cause an allergic contact dermatitis and if there exists a leading allergen.<br /><br /><strong>METHODS: </strong>609 patients with periorbital eczema were assessed with patch testing in 22 hospitals to evaluate the relevance of an allergic contact dermatitis in the pathogenesis of periorbital eczema. Additionally, 116 patients were tested with their own products.<br /><br /><strong>RESULTS: </strong>81% of the cases involving the eyelids were women. A relevant allergic contact dermatitis was found in 52% of the patients with periorbital eczema. Furthermore, a positive patch test was present in every third patient with the clinical diagnosis of an atopic dermatitis. Antibiotics, phenylephrine and thimerosal could be determined to be the leading allergens responsible for allergic periorbital eczema. Positive reactions for potassium dichromate and fragrance mix occurred less frequently in patients with periorbital eczema. 132 positive reactions were found in patients tested with their own products, including 33% with a positive reaction to eye ointments, 15% to face creams, 10% to eye shadows, 10% to makeup, 10% to shampoos and 4% to nail varnish. Only 6% reacted to perfume.<br /><br /><strong>CONCLUSION: </strong>The data underline the importance of performing patch tests in the case of periorbital eczema, especially in atopic patients."
1234545,Ye et al. 1997,Effects of topical antiandrogen and 5-alpha-reductase inhibitors on sebaceous glands in male fuzzy rats,"The fuzzy rat, a genetic mutant between hairless and hairy albino rats, expresses androgen-dependent hypersecretion of sebum and hyperplastic sebaceous glands. Using this model for human acne, we examined the effects of inhibitors of human steroid 5 alpha-reductase isozymes, type I (MK 386) and type II (finasteride), and an androgen receptor blocker (RU58841) on regression of glandular and ductal hyperplasia. The above three agents, 1% weight volume, were dissolved into the vehicle (propylene glycol, alcohol and water) and applied on the backs of peripubertal male rats for 2 months. Control and castrate groups received vehicle alone. At 8 weeks, we examined the size the sebaceous glandular lobules and ducts in split epidermal preparations as well as in frozen sections of skin stained with osmium-potassium dichromate solution. The number of bromodeoxyuridine (BrdU)-positive cells was counted in the glandular lobes in split-skin tissues stained with BrdU immunochemistry. The results revealed that the sizes of both lobes and ducts in castrates were 40-60% smaller than in controls. RU58841 induced glandular and ductal regression equivalent to that in castrates. Finasteride induced a moderate degree of lobular and ductal reduction, whereas MK386 caused only ductal regression. Reduction of BrdU-positive cells in the sebaceous lobes was found in the skin treated with finasteride and RU58841. Serum concentrations of testosterone and dihydrotestosterone showed no significant changes in all drug-treated rats. The weight of the prostatic lobes was reduced significantly in rats treated with finasteride but not by the other two agents. RU58841 effectively counteracted endogenous androgens resulting in a suppression of growth of the sebaceous glands but not the prostate. This rodent model for androgen-dependent hyperplasia of the sebaceous glands is useful for the study of many pharmacological aspects comprising the rate of percutaneous absorption, stability and affinity to target organs of the testing compounds, and selection of adequate vehicle for topical application.","Effects of topical antiandrogen and 5-alpha-reductase inhibitors on sebaceous glands in male fuzzy rats Abs: The fuzzy rat, a genetic mutant between hairless and hairy albino rats, expresses androgen-dependent hypersecretion of sebum and hyperplastic sebaceous glands. Using this model for human acne, we examined the effects of inhibitors of human steroid 5 alpha-reductase isozymes, type I (MK 386) and type II (finasteride), and an androgen receptor blocker (RU58841) on regression of glandular and ductal hyperplasia. The above three agents, 1% weight volume, were dissolved into the vehicle (propylene glycol, alcohol and water) and applied on the backs of peripubertal male rats for 2 months. Control and castrate groups received vehicle alone. At 8 weeks, we examined the size the sebaceous glandular lobules and ducts in split epidermal preparations as well as in frozen sections of skin stained with osmium-potassium dichromate solution. The number of bromodeoxyuridine (BrdU)-positive cells was counted in the glandular lobes in split-skin tissues stained with BrdU immunochemistry. The results revealed that the sizes of both lobes and ducts in castrates were 40-60% smaller than in controls. RU58841 induced glandular and ductal regression equivalent to that in castrates. Finasteride induced a moderate degree of lobular and ductal reduction, whereas MK386 caused only ductal regression. Reduction of BrdU-positive cells in the sebaceous lobes was found in the skin treated with finasteride and RU58841. Serum concentrations of testosterone and dihydrotestosterone showed no significant changes in all drug-treated rats. The weight of the prostatic lobes was reduced significantly in rats treated with finasteride but not by the other two agents. RU58841 effectively counteracted endogenous androgens resulting in a suppression of growth of the sebaceous glands but not the prostate. This rodent model for androgen-dependent hyperplasia of the sebaceous glands is useful for the study of many pharmacological aspects comprising the rate of percutaneous absorption, stability and affinity to target organs of the testing compounds, and selection of adequate vehicle for topical application."
1234544,Katsarou et al. 1997,Study of persistence and loss of patch test reactions to dichromate and cobalt,"Hyposensitization is a poorly understood phenomenon that refers to the conversion from a positive to a negative (or less positive) patch test. We studied 180 cement workers with contact dermatitis, who originally had a total of 163 positive patch test reactions to potassium dichromate and 98 positive reactions to cobalt chloride. They were patch tested a 2nd time after 2-6 years. On the 2nd patch test to dichromate, 103 (63%) remained positive, while reactivity decreased in 33 (20%) and 27 (17%) had become non-reactive. Cobalt sensitivity persisted in 47%, diminished in 13%, and 40% of the patch tests became non-reactive. In 10 patients with persistent patch test reactions and 10 matched patients with diminished reactions or loss of reactivity, circulating T-cell responses to dichromate and cobalt were studied in vivo. Circulating T cells that proliferated only to specific contact allergens were isolated and in all patients they were primarily CD4+. However, in patients with persistent reactions, they were CD4+ CD45RA+ (suppressor - inducer cells). These differences support an immunologic basis for hyposensitization.","Study of persistence and loss of patch test reactions to dichromate and cobalt Abs: Hyposensitization is a poorly understood phenomenon that refers to the conversion from a positive to a negative (or less positive) patch test. We studied 180 cement workers with contact dermatitis, who originally had a total of 163 positive patch test reactions to potassium dichromate and 98 positive reactions to cobalt chloride. They were patch tested a 2nd time after 2-6 years. On the 2nd patch test to dichromate, 103 (63%) remained positive, while reactivity decreased in 33 (20%) and 27 (17%) had become non-reactive. Cobalt sensitivity persisted in 47%, diminished in 13%, and 40% of the patch tests became non-reactive. In 10 patients with persistent patch test reactions and 10 matched patients with diminished reactions or loss of reactivity, circulating T-cell responses to dichromate and cobalt were studied in vivo. Circulating T cells that proliferated only to specific contact allergens were isolated and in all patients they were primarily CD4+. However, in patients with persistent reactions, they were CD4+ CD45RA+ (suppressor - inducer cells). These differences support an immunologic basis for hyposensitization."
1234543,Liu and  Lin 1997,Biphasic effects of chromium compounds on catecholamine secretion from bovine adrenal medullary cells,"CrO3 was found to affect norepinephrine release in a biphasic manner: at concentrations above 100 microM, it inhibited, while at concentrations below 10 microM, it enhanced DMPP- and high K+-induced [3H]norepinephrine (NE) release from bovine adrenal medullary cells. Similar effects were found for K2Cr2O7. CrO3 inhibited the 45Ca2+ uptake induced by DMPP and high K+, suggesting that the voltage-gated Ca2+ channels are possible sites of the inhibitory action of CrO3. CrCl3, possessing a trivalent state in contrast to the hexavalent states of CrO3, K2Cr2O7, inhibited DMPP-induced [3H] release and inhibited, to a lesser extent, high K+-induced [3H]-NE release, suggesting that nicotinic receptors are also possible sites of Cr3+ action. In medullary cells permeabilized with digitonin, both CrO3 and CrCl3 induced [3H]-NE release from cells preloaded with [3H]-NE. In intact cells, CrO3 but not CrCl3 enhanced secretagogue-induced [3H]-NE release and entered into the cells as demonstrated by fluorescence quenching experiments. These results suggest that chromium compounds can induce catecholamine secretion after entering the cytoplasm. The enhancement of norepinephrine release induced by chromium ions appears to be due to interference with the intracellular functions of Ca2+ in the cytoplasm.","Biphasic effects of chromium compounds on catecholamine secretion from bovine adrenal medullary cells Abs: CrO3 was found to affect norepinephrine release in a biphasic manner: at concentrations above 100 microM, it inhibited, while at concentrations below 10 microM, it enhanced DMPP- and high K+-induced [3H]norepinephrine (NE) release from bovine adrenal medullary cells. Similar effects were found for K2Cr2O7. CrO3 inhibited the 45Ca2+ uptake induced by DMPP and high K+, suggesting that the voltage-gated Ca2+ channels are possible sites of the inhibitory action of CrO3. CrCl3, possessing a trivalent state in contrast to the hexavalent states of CrO3, K2Cr2O7, inhibited DMPP-induced [3H] release and inhibited, to a lesser extent, high K+-induced [3H]-NE release, suggesting that nicotinic receptors are also possible sites of Cr3+ action. In medullary cells permeabilized with digitonin, both CrO3 and CrCl3 induced [3H]-NE release from cells preloaded with [3H]-NE. In intact cells, CrO3 but not CrCl3 enhanced secretagogue-induced [3H]-NE release and entered into the cells as demonstrated by fluorescence quenching experiments. These results suggest that chromium compounds can induce catecholamine secretion after entering the cytoplasm. The enhancement of norepinephrine release induced by chromium ions appears to be due to interference with the intracellular functions of Ca2+ in the cytoplasm."
1234542,Susa et al. 1997,"Potent protective effect of melatonin on chromium(VI)-induced DNA single-strand breaks, cytotoxicity, and lipid peroxidation in primary cultures of rat hepatocytes","Incubation of primary cultures of rat hepatocytes with K2Cr2O7 plus the pineal hormone melatonin resulted in a marked decrease in cellular levels of DNA single-strand breaks caused by K2Cr2O7. Cellular treatment with melatonin also suppressed both dichromate-induced cytotoxicity, as evaluated by the leakage of lactate dehydrogenase, and lipid peroxidation, as monitored by malondialdehyde formation. In addition, treatment with melatonin attenuated the suppression of the levels of vitamins E and C as well as the inhibition of catalase activity attributed to K2Cr2O7. However, melatonin had no influence on cellular level of glutathione and the activity of glutathione reductase, glutathione peroxidase, superoxide dismutase, and alkaline phosphatase suppressed by dichromate. Under the same experimental conditions, cellular uptake and distribution of Cr were not affected by melatonin. Electron spin resonance (ESR) studies showed that melatonin did not affect the formation of Cr(V) complexes in the reaction of K2Cr2O7 with reduced glutathione; however, melatonin caused a 25% decrease in the levels of Cr(V)-related hydroxyl radicals in vitro. These results indicate that melatonin protects cells from Cr(VI)-induced DNA strand breaks, cytotoxicity, and lipid peroxidation, possibly through its ability to increase cellular levels of vitamins E and C as well as catalase activity and/or to directly scavenge toxic hydroxyl radicals in cells.","Potent protective effect of melatonin on chromium(VI)-induced DNA single-strand breaks, cytotoxicity, and lipid peroxidation in primary cultures of rat hepatocytes Abs: Incubation of primary cultures of rat hepatocytes with K2Cr2O7 plus the pineal hormone melatonin resulted in a marked decrease in cellular levels of DNA single-strand breaks caused by K2Cr2O7. Cellular treatment with melatonin also suppressed both dichromate-induced cytotoxicity, as evaluated by the leakage of lactate dehydrogenase, and lipid peroxidation, as monitored by malondialdehyde formation. In addition, treatment with melatonin attenuated the suppression of the levels of vitamins E and C as well as the inhibition of catalase activity attributed to K2Cr2O7. However, melatonin had no influence on cellular level of glutathione and the activity of glutathione reductase, glutathione peroxidase, superoxide dismutase, and alkaline phosphatase suppressed by dichromate. Under the same experimental conditions, cellular uptake and distribution of Cr were not affected by melatonin. Electron spin resonance (ESR) studies showed that melatonin did not affect the formation of Cr(V) complexes in the reaction of K2Cr2O7 with reduced glutathione; however, melatonin caused a 25% decrease in the levels of Cr(V)-related hydroxyl radicals in vitro. These results indicate that melatonin protects cells from Cr(VI)-induced DNA strand breaks, cytotoxicity, and lipid peroxidation, possibly through its ability to increase cellular levels of vitamins E and C as well as catalase activity and/or to directly scavenge toxic hydroxyl radicals in cells."
1234541,Igarashi and  Shimada 1997,An improved method for the mouse liver micronucleus test,"We have developed a very practical method for performing the liver micronucleus test in mice. Using this method, we evaluated 11 different types of mutagens, including, 2-acetylaminofluorene, amsacrine, benzene, cyclophosphamide, diethylnitrosamine, 4-dimethylamino-3'-methylazobenzene, N-ethyl-N-nitrosourea, fluorouracil, mitomycin C, potassium chromate (VI) and selenious acid. In order to assess the sensitivity of our method, the peripheral blood reticulocyte micronucleus test was performed in the same mouse. Animals were given test chemicals once and underwent partial hepatectomy (PH) 24 h later in order to induce mitotic stimulation. Peripheral blood was sampled 0, 24, 48 and 72 h after treatment. The incidence of micronucleated hepatocytes was determined 5 days after PH. As a result, diethylnitrosamine and 4-dimethylamino-3'-methylazobenzene, known as liver carcinogens, increased the incidence of micronucleated cells in the liver only. Positive reactions for benzene, on the other hand, were found in the peripheral blood reticulocytes only. The other chemicals showed positive reaction in the liver and peripheral blood reticulocytes with almost the same maximum response of micronucleus induction. Our method was found to have the advantage over Cliets' liver micronucleus test in that it required much less time and was easier to perform procedures and highly sensitive in detecting clastogens. It can be used in combination with the peripheral blood reticulocyte micronucleus test to evaluate test chemicals in two tissues, the liver and the bone marrow, in the same animal. We propose a method of combining this test with the peripheral blood reticulocyte micronucleus test for efficient screening for the clastogenic potential of new chemicals in vivo.","An improved method for the mouse liver micronucleus test Abs: We have developed a very practical method for performing the liver micronucleus test in mice. Using this method, we evaluated 11 different types of mutagens, including, 2-acetylaminofluorene, amsacrine, benzene, cyclophosphamide, diethylnitrosamine, 4-dimethylamino-3'-methylazobenzene, N-ethyl-N-nitrosourea, fluorouracil, mitomycin C, potassium chromate (VI) and selenious acid. In order to assess the sensitivity of our method, the peripheral blood reticulocyte micronucleus test was performed in the same mouse. Animals were given test chemicals once and underwent partial hepatectomy (PH) 24 h later in order to induce mitotic stimulation. Peripheral blood was sampled 0, 24, 48 and 72 h after treatment. The incidence of micronucleated hepatocytes was determined 5 days after PH. As a result, diethylnitrosamine and 4-dimethylamino-3'-methylazobenzene, known as liver carcinogens, increased the incidence of micronucleated cells in the liver only. Positive reactions for benzene, on the other hand, were found in the peripheral blood reticulocytes only. The other chemicals showed positive reaction in the liver and peripheral blood reticulocytes with almost the same maximum response of micronucleus induction. Our method was found to have the advantage over Cliets' liver micronucleus test in that it required much less time and was easier to perform procedures and highly sensitive in detecting clastogens. It can be used in combination with the peripheral blood reticulocyte micronucleus test to evaluate test chemicals in two tissues, the liver and the bone marrow, in the same animal. We propose a method of combining this test with the peripheral blood reticulocyte micronucleus test for efficient screening for the clastogenic potential of new chemicals in vivo."
1234539,Mukherjee et al. 1997,Effects of dietary consumption of black tea infusion alone and in combination with known clastogens on mouse bone marrow chromosomes in vivo,"Black tea infusion in water, in concentrations simulating human consumption, was administered by gavage daily to male Swiss mice for 7 days. One set was given tea once daily and the other twice daily. The mice were then exposed to two known clastogens: chromium (VI) as potassium dichromate and mitomycin C on day 7, and killed after 24 hr. Chromosome damage was studied in preparations made from bone marrow following colchine injection of all mice, and examination of the cells after pretreatment in hypotonic solution, fixation, air drying one and staining with Giemsa solution. No effect was observed in mice given tea once daily. In mice administered tea twice daily, the frequencies of chromosomal aberrations and damaged cells were increased as compared with those of the control in distilled water. Administration of tea twice daily for 7 days could not reduce the clastogenic effects of mitomycin C significantly. The damage due to potassium dichromate was reduced significantly, almost to the level of distilled water. Dietary administration of black tea infusion could therefore significantly protect against clastogenic activity of chromium compounds though it was itself mildly clastogenic.","Effects of dietary consumption of black tea infusion alone and in combination with known clastogens on mouse bone marrow chromosomes in vivo Abs: Black tea infusion in water, in concentrations simulating human consumption, was administered by gavage daily to male Swiss mice for 7 days. One set was given tea once daily and the other twice daily. The mice were then exposed to two known clastogens: chromium (VI) as potassium dichromate and mitomycin C on day 7, and killed after 24 hr. Chromosome damage was studied in preparations made from bone marrow following colchine injection of all mice, and examination of the cells after pretreatment in hypotonic solution, fixation, air drying one and staining with Giemsa solution. No effect was observed in mice given tea once daily. In mice administered tea twice daily, the frequencies of chromosomal aberrations and damaged cells were increased as compared with those of the control in distilled water. Administration of tea twice daily for 7 days could not reduce the clastogenic effects of mitomycin C significantly. The damage due to potassium dichromate was reduced significantly, almost to the level of distilled water. Dietary administration of black tea infusion could therefore significantly protect against clastogenic activity of chromium compounds though it was itself mildly clastogenic."
1234538,Guzzella et al. 1997,Acute toxicity of organophosphorus insecticides to marine invertebrates,,Acute toxicity of organophosphorus insecticides to marine invertebrates Abs: 
1234537,Bataineh et al. 1997,"Effect of long-term ingestion of chromium compounds on aggression, sex behavior and fertility in adult male rat","The effects of long-term ingestion of chromium chloride (trivalent compound) and potassium dichromate (hexavalent compound) was investigated on sexual behavior, aggressive behavior and fertility in male rats. Adult male rats were exposed to chromium chloride and potassium dichromate in drinking water at a concentration of 1000 ppm for 12 weeks. The exposure of male rats to chromium chloride and potassium dichromate reduced the number of mounts. The exposure of male rats to potassium dichromate increased the time to ejaculation. On the other hand, the exposure of male rats to chromium chloride and potassium dichromate increased the post ejaculatory interval. The number of animals ejaculating were reduced in chromium chloride and potassium dichromate exposed male rats. The exposure of male rats to chromium chloride and potassium dichromate decreased lateralizations, boxing bouts and fights with stud male. The exposure of male rats to chromium chloride and potassium dichromate had no effect on fertility. Testes, seminal vesicle and preputial gland weights were significantly reduced in chromium chloride- and potassium dichromate-exposed males. In conclusion, the long-term ingestion of chromium chloride and potassium dichromate would have adverse effects on sexual behavior and territorial aggression in adult male rat.","Effect of long-term ingestion of chromium compounds on aggression, sex behavior and fertility in adult male rat Abs: The effects of long-term ingestion of chromium chloride (trivalent compound) and potassium dichromate (hexavalent compound) was investigated on sexual behavior, aggressive behavior and fertility in male rats. Adult male rats were exposed to chromium chloride and potassium dichromate in drinking water at a concentration of 1000 ppm for 12 weeks. The exposure of male rats to chromium chloride and potassium dichromate reduced the number of mounts. The exposure of male rats to potassium dichromate increased the time to ejaculation. On the other hand, the exposure of male rats to chromium chloride and potassium dichromate increased the post ejaculatory interval. The number of animals ejaculating were reduced in chromium chloride and potassium dichromate exposed male rats. The exposure of male rats to chromium chloride and potassium dichromate decreased lateralizations, boxing bouts and fights with stud male. The exposure of male rats to chromium chloride and potassium dichromate had no effect on fertility. Testes, seminal vesicle and preputial gland weights were significantly reduced in chromium chloride- and potassium dichromate-exposed males. In conclusion, the long-term ingestion of chromium chloride and potassium dichromate would have adverse effects on sexual behavior and territorial aggression in adult male rat."
1234535,Sabatino and  Van Liew 1997,The renal handling of IgG in the aging rat and in experimental kidney disease,"The urinary excretion of total protein, low-MW proteins, albumin, high-MW proteins, and intact IgG was measured in male Wistar rats between the ages of 5-52 weeks, and in rats with experimentally induced glomerular or tubular proteinuria. About 25% of aging rats spontaneously developed focal glomerulosclerosis and a mild glomerular proteinuria. By age 52 weeks, total protein excretion in rats with glomerulosclerosis exceeded that of unaffected rats by a factor of seven (39.5 vs 5.4 mg/24 hr x 100 g body wt), and albumin excretion was seven times higher than IgG excretion in affected rats (21.2 vs 2.9 mg/24 hr x 100 g body wt). Rats with chromate toxicity exhibited a reversible tubular proteinuria, with low-molecular weight protein excretion reaching 16.8 mg/24 hr x 100 g body wt (75% of total protein excretion) at the time of peak toxicity. IgG excretion remained less than 0.6 mg/24 hr x 100 g body wt. Aminonucleoside induced a massive but reversible glomerular proteinuria (204 mg/24 hr x 100 g body wt), with IgG excretion reaching 11.4 mg/24 hr x 100 g body wt (6% of total protein excretion) at the time of peak toxicity. Biochemical and immunochemical studies showed that, while some intact IgG is present in normal rat urine, most IgG immunoreactivity is derived from low-molecular weight catabolic fragments of IgG which interfere with the immunoassay of intact urinary IgG. One of these fragments, probably Fc fragment, may be involved in the pathogenesis of focal segmental glomerulosclerosis.","The renal handling of IgG in the aging rat and in experimental kidney disease Abs: The urinary excretion of total protein, low-MW proteins, albumin, high-MW proteins, and intact IgG was measured in male Wistar rats between the ages of 5-52 weeks, and in rats with experimentally induced glomerular or tubular proteinuria. About 25% of aging rats spontaneously developed focal glomerulosclerosis and a mild glomerular proteinuria. By age 52 weeks, total protein excretion in rats with glomerulosclerosis exceeded that of unaffected rats by a factor of seven (39.5 vs 5.4 mg/24 hr x 100 g body wt), and albumin excretion was seven times higher than IgG excretion in affected rats (21.2 vs 2.9 mg/24 hr x 100 g body wt). Rats with chromate toxicity exhibited a reversible tubular proteinuria, with low-molecular weight protein excretion reaching 16.8 mg/24 hr x 100 g body wt (75% of total protein excretion) at the time of peak toxicity. IgG excretion remained less than 0.6 mg/24 hr x 100 g body wt. Aminonucleoside induced a massive but reversible glomerular proteinuria (204 mg/24 hr x 100 g body wt), with IgG excretion reaching 11.4 mg/24 hr x 100 g body wt (6% of total protein excretion) at the time of peak toxicity. Biochemical and immunochemical studies showed that, while some intact IgG is present in normal rat urine, most IgG immunoreactivity is derived from low-molecular weight catabolic fragments of IgG which interfere with the immunoassay of intact urinary IgG. One of these fragments, probably Fc fragment, may be involved in the pathogenesis of focal segmental glomerulosclerosis."
1234534,Gasiorowski et al. 1997,Inhibition of potassium dichromate mutagenicity by todralazine,"Todralazine, an antihypertensive drug of the hydrazinoph-thalazine group, markedly decreased the mutagenic activity of potassium dichromate in standard bacterial tests. At the highest todralazine dose tested inhibition of potassium dichromate mutagenic activity by approximately 90% in the Ames test and up to 100% (complete) inhibition in the Bacillus subtilis rec- assay was observed. Spectrophotometric analyses proved that todralazine induced reduction of Cr(VI) to Cr(III) and complexation of Cr(III) ions. These spectro-photometric results may be a presumptive explanation of the observed mutagenic activity decrease, as it is known that Cr(III) is poorly transported across cell membranes and therefore is not mutagenic to bacterial cells. We perceive our experiments as an example of attempts which should lead to an effective reduction in chromium genotoxic and carcinogenic activity in exposed individuals.","Inhibition of potassium dichromate mutagenicity by todralazine Abs: Todralazine, an antihypertensive drug of the hydrazinoph-thalazine group, markedly decreased the mutagenic activity of potassium dichromate in standard bacterial tests. At the highest todralazine dose tested inhibition of potassium dichromate mutagenic activity by approximately 90% in the Ames test and up to 100% (complete) inhibition in the Bacillus subtilis rec- assay was observed. Spectrophotometric analyses proved that todralazine induced reduction of Cr(VI) to Cr(III) and complexation of Cr(III) ions. These spectro-photometric results may be a presumptive explanation of the observed mutagenic activity decrease, as it is known that Cr(III) is poorly transported across cell membranes and therefore is not mutagenic to bacterial cells. We perceive our experiments as an example of attempts which should lead to an effective reduction in chromium genotoxic and carcinogenic activity in exposed individuals."
1234533,Ali 1997,Occupational dermatitis in the manufacture of color television tubes,"An outbreak of dermatitis occurred in the Flow Coat sector of a large and modern color television factory. After investigating the working procedures in this area, a risk of contamination of the skin and clothing with ammonium dichromate was found when ammonium dichromate was weighed and mixed with polyvinyl alcohol (PVA). All of the workers involved in this process were clinically examined; 9 of 18 showed dermatitis to the back of the hands and forearms. Three of these workers were transferred from the sector and were cured of their dermatitis. Patch tests were carried out using 40 allergens, including those used in the Flow Coat process. The tests for PVA and for the phosphorescent blue, green, and red pigments gave negative results at the three concentrations tested. A high incidence of sensitization was found; 9 of 18 (50%) of the workers were found to be sensitized to ammonium dichromate, which is used as a fixer. The preventive measures adopted consisted of improving the quality of the personal protective equipment (PPE) and transferring the weighing and mixing of dichromate to the company laboratory. During the next 18 months, there were no new cases of dermatitis in the Flow Coat sector.","Occupational dermatitis in the manufacture of color television tubes Abs: An outbreak of dermatitis occurred in the Flow Coat sector of a large and modern color television factory. After investigating the working procedures in this area, a risk of contamination of the skin and clothing with ammonium dichromate was found when ammonium dichromate was weighed and mixed with polyvinyl alcohol (PVA). All of the workers involved in this process were clinically examined; 9 of 18 showed dermatitis to the back of the hands and forearms. Three of these workers were transferred from the sector and were cured of their dermatitis. Patch tests were carried out using 40 allergens, including those used in the Flow Coat process. The tests for PVA and for the phosphorescent blue, green, and red pigments gave negative results at the three concentrations tested. A high incidence of sensitization was found; 9 of 18 (50%) of the workers were found to be sensitized to ammonium dichromate, which is used as a fixer. The preventive measures adopted consisted of improving the quality of the personal protective equipment (PPE) and transferring the weighing and mixing of dichromate to the company laboratory. During the next 18 months, there were no new cases of dermatitis in the Flow Coat sector."
1234532,Ortega et al. 1997,Isolation of Cryptosporidium parvum and Cyclospora cayetanensis from vegetables collected in markets of an endemic region in Peru,"Cryptosporidium parvum and Cyclospora cayetanensis are protozoan pathogens that cause prolonged diarrhea in both immunocompetent and immunocompromised hosts. Cryptosporidium parvum can be transmitted via the fecal-oral route, while the exact mechanisms of transmission of Cyclospora cayetanensis have not been fully determined. Humans appear to be the sole host for the latter and a distinct seasonality has been observed in endemic areas around the world. Samples of vegetables were collected at several small markets in a periurban slum in Peru during the seasons of high and low incidence. The vegetables were washed, the supernatants were collected and centrifuged, and the pellets were resuspended in a solution of 2.5% potassium dichromate. Pellets were examined using direct microscopic observation, acid-fast staining, and immunofluorescent assays for C. parvum and Cyclospora cayetanensis oocysts. Samples were collected during three time periods: the season of low incidence, the beginning of the season of high incidence, and end of the season of high incidence. Of the total vegetables examined, 14.5% contained C. parvum oocysts and 1.8% had Cyclospora oocysts. Thus, market vegetables may provide a route by which Cryptosporidium and Cyclospora can be transmitted. Our study also suggests that washing vegetables does not completely remove Cryptosporidium and Cyclospora oocysts.","Isolation of Cryptosporidium parvum and Cyclospora cayetanensis from vegetables collected in markets of an endemic region in Peru Abs: Cryptosporidium parvum and Cyclospora cayetanensis are protozoan pathogens that cause prolonged diarrhea in both immunocompetent and immunocompromised hosts. Cryptosporidium parvum can be transmitted via the fecal-oral route, while the exact mechanisms of transmission of Cyclospora cayetanensis have not been fully determined. Humans appear to be the sole host for the latter and a distinct seasonality has been observed in endemic areas around the world. Samples of vegetables were collected at several small markets in a periurban slum in Peru during the seasons of high and low incidence. The vegetables were washed, the supernatants were collected and centrifuged, and the pellets were resuspended in a solution of 2.5% potassium dichromate. Pellets were examined using direct microscopic observation, acid-fast staining, and immunofluorescent assays for C. parvum and Cyclospora cayetanensis oocysts. Samples were collected during three time periods: the season of low incidence, the beginning of the season of high incidence, and end of the season of high incidence. Of the total vegetables examined, 14.5% contained C. parvum oocysts and 1.8% had Cyclospora oocysts. Thus, market vegetables may provide a route by which Cryptosporidium and Cyclospora can be transmitted. Our study also suggests that washing vegetables does not completely remove Cryptosporidium and Cyclospora oocysts."
1234531,Garcia-Sanz et al. 1998,Three-dimensional microcomputed tomography of renal vasculature in rats,"Current microscopic methods to view renal microvasculature reveal only a very limited portion of the total renal volume. Identification of connectivity for postglomerular vessels in the cortex and the medulla during functional states related to changes in sodium excretion will help better to understand the coupling of renal vasculature to tubular function. The purpose of this study was to investigate the possibility of visualizing the continuity of pre- and postglomerular vasculature using three-dimensional micro-computed tomography (micro-CT). Kidneys from normal rats were perfusion fixed in situ at physiological pressure, filled with latex microfil containing lead chromate, and embedded in plastic. The micro-CT scans of the intact kidneys were carried out on a rotating stage illuminated either by a synchrotron x-ray source or a conventional x-ray spectroscopy tube. Images were reconstructed by a filtered backprojection algorithm and volume-rendering techniques were utilized to display the vasculature. The reconstructed images clearly showed the large distribution vessels and the venous drainage of the kidneys, while pre- and postglomerular vessels and their vascular connections throughout the kidney were displayed in great detail. Efferent arterioles showed the characteristics of their peritubular capillary beds in the cortical and medullary regions. The vascular volume of the cortex was 27%, the outer stripe of the outer medulla 18%, the inner stripe of the outer medulla 30%, and the inner medulla 18%. In conclusion, micro-CT is a promising method to evaluate renal vascular architecture relative to physiological and pathological alterations.","Three-dimensional microcomputed tomography of renal vasculature in rats Abs: Current microscopic methods to view renal microvasculature reveal only a very limited portion of the total renal volume. Identification of connectivity for postglomerular vessels in the cortex and the medulla during functional states related to changes in sodium excretion will help better to understand the coupling of renal vasculature to tubular function. The purpose of this study was to investigate the possibility of visualizing the continuity of pre- and postglomerular vasculature using three-dimensional micro-computed tomography (micro-CT). Kidneys from normal rats were perfusion fixed in situ at physiological pressure, filled with latex microfil containing lead chromate, and embedded in plastic. The micro-CT scans of the intact kidneys were carried out on a rotating stage illuminated either by a synchrotron x-ray source or a conventional x-ray spectroscopy tube. Images were reconstructed by a filtered backprojection algorithm and volume-rendering techniques were utilized to display the vasculature. The reconstructed images clearly showed the large distribution vessels and the venous drainage of the kidneys, while pre- and postglomerular vessels and their vascular connections throughout the kidney were displayed in great detail. Efferent arterioles showed the characteristics of their peritubular capillary beds in the cortical and medullary regions. The vascular volume of the cortex was 27%, the outer stripe of the outer medulla 18%, the inner stripe of the outer medulla 30%, and the inner medulla 18%. In conclusion, micro-CT is a promising method to evaluate renal vascular architecture relative to physiological and pathological alterations."
1234530,Brasch and  Geier 1997,Patch test results in schoolchildren. Results from the Information Network of Departments of Dermatology (IVDK) and the German Contact Dermatitis Research Group (DKG),"Our aim was to explore the current spectrum of contact allergens in schoolchildren, as a basis for diagnosis and prevention of allergic contact dermatitis. Results of patch tests in children 6-15 years old, performed in the years 1990-1995 by 22 centres of the German Contact Dermatitis Research Group and filed by the Information Network of Departments of Dermatology, were analysed and evaluated retrospectively, including epidemiologic data. Children with positive tests (62 out of 156 boys and 108 out of 260 girls tested) had a higher frequency of allergic contact dermatitis and a lower frequency of atopic dermatitis than patch test negative ones. 16 distinct allergens elicited positive reactions in &gt; or = 1% of the children tested. Reactions to nickel sulfate occurred in 15.9% of all children tested, but in 25.0% of girls 14/15 years old, and in only 4.5% of boys 6-13 years old. Double-sensitizations with cobalt salts, potassium dichromate and palladium were seen. Mercury compounds were found in 2nd place (thimerosal: all children: 11.3%; 6-13 years old: 14.3%; 14/15 years old: 8.0%), followed by fragrance allergens. We conclude that contact allergy in children is related to their sex and age. Prophylaxis against nickel, mercury, and fragrance allergy needs to be improved. A shortened standard series may be sufficient for testing children.","Patch test results in schoolchildren. Results from the Information Network of Departments of Dermatology (IVDK) and the German Contact Dermatitis Research Group (DKG) Abs: Our aim was to explore the current spectrum of contact allergens in schoolchildren, as a basis for diagnosis and prevention of allergic contact dermatitis. Results of patch tests in children 6-15 years old, performed in the years 1990-1995 by 22 centres of the German Contact Dermatitis Research Group and filed by the Information Network of Departments of Dermatology, were analysed and evaluated retrospectively, including epidemiologic data. Children with positive tests (62 out of 156 boys and 108 out of 260 girls tested) had a higher frequency of allergic contact dermatitis and a lower frequency of atopic dermatitis than patch test negative ones. 16 distinct allergens elicited positive reactions in &gt; or = 1% of the children tested. Reactions to nickel sulfate occurred in 15.9% of all children tested, but in 25.0% of girls 14/15 years old, and in only 4.5% of boys 6-13 years old. Double-sensitizations with cobalt salts, potassium dichromate and palladium were seen. Mercury compounds were found in 2nd place (thimerosal: all children: 11.3%; 6-13 years old: 14.3%; 14/15 years old: 8.0%), followed by fragrance allergens. We conclude that contact allergy in children is related to their sex and age. Prophylaxis against nickel, mercury, and fragrance allergy needs to be improved. A shortened standard series may be sufficient for testing children."
1234529,Susa et al. 1998,Protective effect of diethyldithiocarbamate pretreatment on chromium (VI)-induced cytotoxicity and lipid peroxidation in primary cultures of rat hepatocytes,"Pretreatment of primary cultures of rat hepatocytes with sodium diethyldithiocarbamate (DDTC) for 15 min prior to exposure to K2Cr2O7 resulted in a marked decrease in dichromate-induced cytotoxicity, as evaluated by the leakage of lactate dehydrogenase, and in lipid peroxidation, as monitored by malondialdehyde formation. In addition, pretreatment with DDTC attenuated the suppression of the level of vitamin E attributed to K2Cr2O7. However, DDTC pretreatment had no effect on the cellular levels of glutathione or vitamin C or on the activity of the glutathione reductase, glutathione peroxidase, superoxide dismutase or alkaline phosphatase suppressed by dichromate. Under the same experimental conditions, cellular uptake or distribution of chromium was not affected by DDTC. These results indicate that the protective effect of DDTC on chromium (VI)-induced cytotoxicity as well as lipid peroxidation may be associated with the level of nonenzymatic antioxidants such as vitamin E.","Protective effect of diethyldithiocarbamate pretreatment on chromium (VI)-induced cytotoxicity and lipid peroxidation in primary cultures of rat hepatocytes Abs: Pretreatment of primary cultures of rat hepatocytes with sodium diethyldithiocarbamate (DDTC) for 15 min prior to exposure to K2Cr2O7 resulted in a marked decrease in dichromate-induced cytotoxicity, as evaluated by the leakage of lactate dehydrogenase, and in lipid peroxidation, as monitored by malondialdehyde formation. In addition, pretreatment with DDTC attenuated the suppression of the level of vitamin E attributed to K2Cr2O7. However, DDTC pretreatment had no effect on the cellular levels of glutathione or vitamin C or on the activity of the glutathione reductase, glutathione peroxidase, superoxide dismutase or alkaline phosphatase suppressed by dichromate. Under the same experimental conditions, cellular uptake or distribution of chromium was not affected by DDTC. These results indicate that the protective effect of DDTC on chromium (VI)-induced cytotoxicity as well as lipid peroxidation may be associated with the level of nonenzymatic antioxidants such as vitamin E."
1234528,Stift et al. 1998,Liver transplantation for potassium dichromate poisoning,"IPA COPYRIGHT: ASHP Recovery after liver transplantation is reported in a 16-yr-old boy in whom vomiting, diffuse abdominal pain, and acute renal and liver failure developed after ingesting an unknown quantity of potassium dichromate in a suicide attempt. Renal and liver functions deteriorated despite supportive treatment, intravenous dimercaprol administered at a dose of 250 mg twice daily, hemodialysis, and plasmapheresis. Decreasing serum chromium levels indicated an accumulation in the liver. Orthotopic cadaveric liver transplantation was performed on day 6. Serum chromium decreased to a value that was 20% of the initial level. Histopathological examination of the explanted liver showed diffuse hepatocellular necrosis. The patient was discharged with normal laboratory findings on the 14th postoperative day.","Liver transplantation for potassium dichromate poisoning Abs: IPA COPYRIGHT: ASHP Recovery after liver transplantation is reported in a 16-yr-old boy in whom vomiting, diffuse abdominal pain, and acute renal and liver failure developed after ingesting an unknown quantity of potassium dichromate in a suicide attempt. Renal and liver functions deteriorated despite supportive treatment, intravenous dimercaprol administered at a dose of 250 mg twice daily, hemodialysis, and plasmapheresis. Decreasing serum chromium levels indicated an accumulation in the liver. Orthotopic cadaveric liver transplantation was performed on day 6. Serum chromium decreased to a value that was 20% of the initial level. Histopathological examination of the explanted liver showed diffuse hepatocellular necrosis. The patient was discharged with normal laboratory findings on the 14th postoperative day."
1234527,Ingber et al. 1998,Detergents and bleaches are sources of chromium contact dermatitis in Israel,"Total chromium levels were determined in 38 detergents and 12 bleaches on the market in Israel (45 locally produced, 5 imported). The samples were analyzed by Zeeman-corrected graphite furnace atomic absorption spectrophotometry. Chromium levels were higher than 5 ppm in 28 (56%) of the 50 products, from 1 to 5 ppm in 16 (32%), and lower than 1 ppm in only 6 (12%). Among the 5 imported products, only 1 had a chromium level below 1 ppm and the other 4 (1 from Germany, 3 from the USA) had high levels. Since a most 90% of the detergents and bleaches examined contained chromium levels higher than 1 ppm, it is concluded that these consumer products may be the cause of the high incidence of chromium sensitivity in Israel.","Detergents and bleaches are sources of chromium contact dermatitis in Israel Abs: Total chromium levels were determined in 38 detergents and 12 bleaches on the market in Israel (45 locally produced, 5 imported). The samples were analyzed by Zeeman-corrected graphite furnace atomic absorption spectrophotometry. Chromium levels were higher than 5 ppm in 28 (56%) of the 50 products, from 1 to 5 ppm in 16 (32%), and lower than 1 ppm in only 6 (12%). Among the 5 imported products, only 1 had a chromium level below 1 ppm and the other 4 (1 from Germany, 3 from the USA) had high levels. Since a most 90% of the detergents and bleaches examined contained chromium levels higher than 1 ppm, it is concluded that these consumer products may be the cause of the high incidence of chromium sensitivity in Israel."
1234525,Delmas et al. 1998,"Hsp72 mRNA production in cultured human cells submitted to nonlethal aggression by heat, ethanol, or propanol. Application to the detection of low concentrations of chromium(VI) (potassium dichromate)","The HT29 and HepG2 human cell lines have been shown to express stress proteins (heat shock proteins, HSP) when submitted to a variety of sublethal environmental aggressions. In the present study, these cells were submitted to standardized mild aggression by heat, ethanol, or propan-1-ol in vitro. Subsequent formation of the hsp72 mRNA was measured by a very specific RNase protection method using a radiolabeled antisense RNA probe. The accumulation of the mRNA coding for the HSP72 stress proteins was found to be maximum within 3 h after the aggression. Results were obtained faster and were much more interpretable than those from the classical method involving the autoradiography of electrophoretically separated 35S-labeled proteins, especially in the case of very weak, threshold-level, aggressions. When this model was used as a biological system for the detection of low concentrations of chromium(VI) (Cr2O7(2-)), it was possible to detect concentrations as low as 0.5 mumol/L. This indicates that measuring indices of stress induction in human cultured cells can be several orders of magnitude more sensitive than the commercial Microtox assay used for detecting low levels of pollution.","Hsp72 mRNA production in cultured human cells submitted to nonlethal aggression by heat, ethanol, or propanol. Application to the detection of low concentrations of chromium(VI) (potassium dichromate) Abs: The HT29 and HepG2 human cell lines have been shown to express stress proteins (heat shock proteins, HSP) when submitted to a variety of sublethal environmental aggressions. In the present study, these cells were submitted to standardized mild aggression by heat, ethanol, or propan-1-ol in vitro. Subsequent formation of the hsp72 mRNA was measured by a very specific RNase protection method using a radiolabeled antisense RNA probe. The accumulation of the mRNA coding for the HSP72 stress proteins was found to be maximum within 3 h after the aggression. Results were obtained faster and were much more interpretable than those from the classical method involving the autoradiography of electrophoretically separated 35S-labeled proteins, especially in the case of very weak, threshold-level, aggressions. When this model was used as a biological system for the detection of low concentrations of chromium(VI) (Cr2O7(2-)), it was possible to detect concentrations as low as 0.5 mumol/L. This indicates that measuring indices of stress induction in human cultured cells can be several orders of magnitude more sensitive than the commercial Microtox assay used for detecting low levels of pollution."
1234524,Stefanovi? et al. 1998,The acidophilic nature of neuronal Golgi impregnation,"The mechanisms of Golgi impregnation of neurons has remained enigmatic for decades. Recently, it was suggested that divalent (di)chromate anions play a role in the Golgi impregnation process. Therefore, we incubated slices of (para)formaldehyde-fixed rat brain tissue in solutions of potassium (di)chromate, phosphate, chloride or nitrate at pH 6 or 7. Slices were then immersed in solutions of silver nitrate and processed for light microscopical analysis. At pH 6, dichromate probes resulted in dense and homogeneous impregnation of neuronal cytoplasm (typical impregnation). At pH 7, chromate probes showed solely partial cytoplasmic and heavy nuclear-region neuron impregnation (atypical impregnation). Phosphate probes at pH 6 resulted in typical impregnation, whereas at pH 7 phosphate probes gave atypical impregnation. Both at pH 6 and 7, chloride and nitrate probes did not yield any Golgi impregnation. These findings confirmed the pH-dependence of silver-chromate Golgi impregnation as well as the correctness of corresponding acidic silver-phosphate impregnation. Our study revealed a previously unknown, strong anion-dependence of Golgi impregnation, suggesting that hydrogenated monovalent anions are carriers of the neuron impregnation.","The acidophilic nature of neuronal Golgi impregnation Abs: The mechanisms of Golgi impregnation of neurons has remained enigmatic for decades. Recently, it was suggested that divalent (di)chromate anions play a role in the Golgi impregnation process. Therefore, we incubated slices of (para)formaldehyde-fixed rat brain tissue in solutions of potassium (di)chromate, phosphate, chloride or nitrate at pH 6 or 7. Slices were then immersed in solutions of silver nitrate and processed for light microscopical analysis. At pH 6, dichromate probes resulted in dense and homogeneous impregnation of neuronal cytoplasm (typical impregnation). At pH 7, chromate probes showed solely partial cytoplasmic and heavy nuclear-region neuron impregnation (atypical impregnation). Phosphate probes at pH 6 resulted in typical impregnation, whereas at pH 7 phosphate probes gave atypical impregnation. Both at pH 6 and 7, chloride and nitrate probes did not yield any Golgi impregnation. These findings confirmed the pH-dependence of silver-chromate Golgi impregnation as well as the correctness of corresponding acidic silver-phosphate impregnation. Our study revealed a previously unknown, strong anion-dependence of Golgi impregnation, suggesting that hydrogenated monovalent anions are carriers of the neuron impregnation."
1234522,Ulvi 1998,Spectrophotometric studies on the photostability of some thiazide diuretics in ethanolic solution,"First derivative and dual-wavelength spectrophotometric methods were used in the quantum yield determination of the photochemical decomposition reactions of three thiazide diuretics (chlorothiazide, hydrochlorothiazide and trichloromethiazide) in ethanolic solution. The radiation absorbed by the compounds was measured using iron(III) oxalate actinometry based on absorption spectrophotometry. An apparatus is described in which the drugs were irradiated in quartz cuvettes cooled by water in a stand built on a magnetic stirrer. The wavelength region available to the reaction cuvette was restricted to 313 nm with chemical potassium chromate filter solutions and a Corning filter plate. Chlorothiazide proved to be more photostable than hydrochlorothiazide and trichloromethiazide in ethanol.","Spectrophotometric studies on the photostability of some thiazide diuretics in ethanolic solution Abs: First derivative and dual-wavelength spectrophotometric methods were used in the quantum yield determination of the photochemical decomposition reactions of three thiazide diuretics (chlorothiazide, hydrochlorothiazide and trichloromethiazide) in ethanolic solution. The radiation absorbed by the compounds was measured using iron(III) oxalate actinometry based on absorption spectrophotometry. An apparatus is described in which the drugs were irradiated in quartz cuvettes cooled by water in a stand built on a magnetic stirrer. The wavelength region available to the reaction cuvette was restricted to 313 nm with chemical potassium chromate filter solutions and a Corning filter plate. Chlorothiazide proved to be more photostable than hydrochlorothiazide and trichloromethiazide in ethanol."
1234521,Gallenkemper et al. 1998,Contact sensitization in chronic venous insufficiency: modern wound dressings,"Patch tests with an expanded European standard series and 20 different wound dressings revealed sensitization in 78% of all (36) patients. The charts of allergens were headed by ointment bases (wool wax alcohols sensitization in 33% of all patients; Amerchol L-101 19.4%; cetearyl alcohol 13.9%; propylene glycol 8.3%), followed by plant resins/ethereal oils (balsam of Peru 22.2%; colophony 13.9%, fragrance mix 8.3%; propolis 5.6%) and topical antibiotics (neomycin sulfate 16.7%, chloramphenicol 13.9%), while usually common sensitizers like metal salts were not found as often (nickel sulfate 16.7%; potassium dichromate 13.9%; cobalt chloride 5.6%). Sensitization to modern wound dressings was found in 8.3% (3 cases) and was caused by propylene glycol as an ingredient of hydrogels; no sensitization was found to hydrocolloids, alginates or polyurethane foams. The overall sensitization rate in 2nd degree CVI was nearly as high as in 3rd degree CVI, but sensitization to ointments, their additives and topical antibiotics was significantly higher in 3rd degree CVI. Significant differences in sensitization frequencies to individual allergens were found between male and female patients. Our investigation points out the high risk of sensitization in 2nd as well as 3rd degree CVI, especially to ointment bases and active principles of topical drugs. Even wound dressings may cause allergic contact reactions.","Contact sensitization in chronic venous insufficiency: modern wound dressings Abs: Patch tests with an expanded European standard series and 20 different wound dressings revealed sensitization in 78% of all (36) patients. The charts of allergens were headed by ointment bases (wool wax alcohols sensitization in 33% of all patients; Amerchol L-101 19.4%; cetearyl alcohol 13.9%; propylene glycol 8.3%), followed by plant resins/ethereal oils (balsam of Peru 22.2%; colophony 13.9%, fragrance mix 8.3%; propolis 5.6%) and topical antibiotics (neomycin sulfate 16.7%, chloramphenicol 13.9%), while usually common sensitizers like metal salts were not found as often (nickel sulfate 16.7%; potassium dichromate 13.9%; cobalt chloride 5.6%). Sensitization to modern wound dressings was found in 8.3% (3 cases) and was caused by propylene glycol as an ingredient of hydrogels; no sensitization was found to hydrocolloids, alginates or polyurethane foams. The overall sensitization rate in 2nd degree CVI was nearly as high as in 3rd degree CVI, but sensitization to ointments, their additives and topical antibiotics was significantly higher in 3rd degree CVI. Significant differences in sensitization frequencies to individual allergens were found between male and female patients. Our investigation points out the high risk of sensitization in 2nd as well as 3rd degree CVI, especially to ointment bases and active principles of topical drugs. Even wound dressings may cause allergic contact reactions."
1234520,Lainson and  Naiff 1998,"Eimeria peltocephali n. sp., (Apicomplexa:Eimeriidae) from the freshwater turtle Peltocephalus dumerilianus (Chelonia:Pelomusidae) and Eimeria molossi n. sp., from the bat, Molossus ater (Mammalia:Chiroptera)","The oocyst is described of Eimeria peltocephali n.sp. from faeces of the freshwater turtle Peltocephalus dumerilianus from Barcelos, State of Amazonas, Brazil. Sporulation is exogenous and fully developed oocysts are elongate, ellipsoidal or cylindrical, frequently curved to a banana-shape, 54.4 x 19.1 (37.5-68.7 x 18.7-20.0 microns), shape-index 2.8 (1.8-3.9). The oocyst wall is a single thin, colourless layer about 1 micron thick, with no micropyle. There is a bulky oocyst residuum, at first spherical to ellipsoidal, 19 x 16 (16.2-26.2 x 16-21.5 microns), but becoming dispersed on maturation. There are no polar bodies. The sporocysts, 19.1 x 6.8 (17.5-21.2 x 6.2-7.5 microns), shape-index 2.8 (2.3-3.2), are usually disposed in pairs at each end of the oocyst, and bear an inconspicuous Stieda body in the form of a flat cap. The sporozoites are elongate and slightly curved around the residuum. No refractile bodies were seen. Eimeria molossi n.sp., is described from the molossid bat Molossus ater. Sporulation is exogenous and the mature oocysts are predominantly broadly ellipsoidal, 23.4 x 17.5 (18-30 x 15-22.5 microns), shape-index 1.3 (1-1.6). The oocyst wall is about 2 microns thick, and of three layers: an inner thin, colourless one and two outer layers which are thicker, yellowish-brown, prominently striated and in close apposition. There is no micropyle or oocyst residuum, but one and occasionally two polar bodies are usually present. Sporocysts are ellipsoidal, 10.2 x 7.5 (10-12.5 x 7.5 microns), shape-index 1.4 (1.3-1.7) with an inconspicuous Stieda body. Endogenous stages are described in the epithelial cells of the small intestine.","Eimeria peltocephali n. sp., (Apicomplexa:Eimeriidae) from the freshwater turtle Peltocephalus dumerilianus (Chelonia:Pelomusidae) and Eimeria molossi n. sp., from the bat, Molossus ater (Mammalia:Chiroptera) Abs: The oocyst is described of Eimeria peltocephali n.sp. from faeces of the freshwater turtle Peltocephalus dumerilianus from Barcelos, State of Amazonas, Brazil. Sporulation is exogenous and fully developed oocysts are elongate, ellipsoidal or cylindrical, frequently curved to a banana-shape, 54.4 x 19.1 (37.5-68.7 x 18.7-20.0 microns), shape-index 2.8 (1.8-3.9). The oocyst wall is a single thin, colourless layer about 1 micron thick, with no micropyle. There is a bulky oocyst residuum, at first spherical to ellipsoidal, 19 x 16 (16.2-26.2 x 16-21.5 microns), but becoming dispersed on maturation. There are no polar bodies. The sporocysts, 19.1 x 6.8 (17.5-21.2 x 6.2-7.5 microns), shape-index 2.8 (2.3-3.2), are usually disposed in pairs at each end of the oocyst, and bear an inconspicuous Stieda body in the form of a flat cap. The sporozoites are elongate and slightly curved around the residuum. No refractile bodies were seen. Eimeria molossi n.sp., is described from the molossid bat Molossus ater. Sporulation is exogenous and the mature oocysts are predominantly broadly ellipsoidal, 23.4 x 17.5 (18-30 x 15-22.5 microns), shape-index 1.3 (1-1.6). The oocyst wall is about 2 microns thick, and of three layers: an inner thin, colourless one and two outer layers which are thicker, yellowish-brown, prominently striated and in close apposition. There is no micropyle or oocyst residuum, but one and occasionally two polar bodies are usually present. Sporocysts are ellipsoidal, 10.2 x 7.5 (10-12.5 x 7.5 microns), shape-index 1.4 (1.3-1.7) with an inconspicuous Stieda body. Endogenous stages are described in the epithelial cells of the small intestine."
1234519,Checchi et al. 1998,Contamination of the turbine air chamber: a risk of cross infection,"In the present work, we evaluated (a) the influx of contaminating fluid into the air chamber when a high-speed turbine stops rotating, (b) the significance of a series of variables (type of handpiece and dental unit, shape of the bur, number of stops set on the turbine) which condition it, and (c) the time required to expel the contaminating fluid from the turbine head. Results showed that contamination takes place every time the turbine stops rotating with the bur in contact with an external fluid. The main variable affecting the influx of contaminating fluid into the air chamber of the turbine head was represented by the shape of the bur (F=54.9; p&lt;0.01). Another significant variable was the type of handpiece and dental unit (F=7.3; p&lt;0.01). The number of stops set on the turbine was irrelevant (F=0.03; p=n.s.). The expulsion of the contaminant from the turbine head showed 2 different exponential rates: a very rapid-elimination phase within 30 s and a slow-elimination phase between 60 and 300 s. In order to remove over 99% of the contaminant from the air chamber, a turbine had to run for more than 4-7 min depending on the type of the handpiece. In conclusion, data from the present study suggest that a significant cross-infection potential exists with high-speed handpieces whenever they are only externally scrubbed and disinfected so the internal cleaning and sterilization between patients is mandatory. The practice of flushing by running the turbines between patients should be discouraged.","Contamination of the turbine air chamber: a risk of cross infection Abs: In the present work, we evaluated (a) the influx of contaminating fluid into the air chamber when a high-speed turbine stops rotating, (b) the significance of a series of variables (type of handpiece and dental unit, shape of the bur, number of stops set on the turbine) which condition it, and (c) the time required to expel the contaminating fluid from the turbine head. Results showed that contamination takes place every time the turbine stops rotating with the bur in contact with an external fluid. The main variable affecting the influx of contaminating fluid into the air chamber of the turbine head was represented by the shape of the bur (F=54.9; p&lt;0.01). Another significant variable was the type of handpiece and dental unit (F=7.3; p&lt;0.01). The number of stops set on the turbine was irrelevant (F=0.03; p=n.s.). The expulsion of the contaminant from the turbine head showed 2 different exponential rates: a very rapid-elimination phase within 30 s and a slow-elimination phase between 60 and 300 s. In order to remove over 99% of the contaminant from the air chamber, a turbine had to run for more than 4-7 min depending on the type of the handpiece. In conclusion, data from the present study suggest that a significant cross-infection potential exists with high-speed handpieces whenever they are only externally scrubbed and disinfected so the internal cleaning and sterilization between patients is mandatory. The practice of flushing by running the turbines between patients should be discouraged."
1234518,Larrain et al. 1998,Sensitivity of the meiofaunal copepod Tisbe longicornis to K2Cr2O7 under varying temperature regimes,BIOSIS COPYRIGHT: BIOL ABS. RRM RESEARCH ARTICLE TISBE-LONGICORNIS BIOINDICATOR MEIOFAUNAL COPEPOD TEMPERATURE REGIME POTASSIUM DICHROMATE TOXIN POLLUTION STATUS TOXICOLOGY ECOTOXICOLOGY POLLUTION,Sensitivity of the meiofaunal copepod Tisbe longicornis to K2Cr2O7 under varying temperature regimes Abs: BIOSIS COPYRIGHT: BIOL ABS. RRM RESEARCH ARTICLE TISBE-LONGICORNIS BIOINDICATOR MEIOFAUNAL COPEPOD TEMPERATURE REGIME POTASSIUM DICHROMATE TOXIN POLLUTION STATUS TOXICOLOGY ECOTOXICOLOGY POLLUTION
1234517,Tesfai et al. 1998,Chromium can reduce the mutagenic effects of benzo[a]pyrene diolepoxide in normal human fibroblasts via an oxidative stress mechanism,"The interaction of multiple carcinogens on human cells has not been extensively examined. This study reports the results of experiments in which normal human fibroblasts were exposed to both benzo[a]pyrene diolepoxide (BPDE) and potassium dichromate. The effect of four different treatment protocols on the cloning ability of the cells and the mutant frequency of the HPRT gene was determined. The combined treatment of both carcinogens caused a slightly greater than additive decrease in the cloning ability of the cells when compared to cells treated with the individual carcinogens. The result was the same regardless of the treatment protocol used in the experiment. The results of the mutant frequency experiments, however, varied dramatically with the protocol employed. The mutant frequency in cells which were simultaneously treated with both carcinogens was dramatically reduced from the mutant frequency found when cells were treated with BPDE alone. This antagonistic effect was not present when cells were either pretreated with potassium dichromate prior to BPDE or incubated with potassium dichromate following BPDE treatment. The observed antagonistic effect was the result of oxidative stress produced by chromium since it was completely or nearly completely reversed by the addition of either vitamin E or catalase to the cultures.","Chromium can reduce the mutagenic effects of benzo[a]pyrene diolepoxide in normal human fibroblasts via an oxidative stress mechanism Abs: The interaction of multiple carcinogens on human cells has not been extensively examined. This study reports the results of experiments in which normal human fibroblasts were exposed to both benzo[a]pyrene diolepoxide (BPDE) and potassium dichromate. The effect of four different treatment protocols on the cloning ability of the cells and the mutant frequency of the HPRT gene was determined. The combined treatment of both carcinogens caused a slightly greater than additive decrease in the cloning ability of the cells when compared to cells treated with the individual carcinogens. The result was the same regardless of the treatment protocol used in the experiment. The results of the mutant frequency experiments, however, varied dramatically with the protocol employed. The mutant frequency in cells which were simultaneously treated with both carcinogens was dramatically reduced from the mutant frequency found when cells were treated with BPDE alone. This antagonistic effect was not present when cells were either pretreated with potassium dichromate prior to BPDE or incubated with potassium dichromate following BPDE treatment. The observed antagonistic effect was the result of oxidative stress produced by chromium since it was completely or nearly completely reversed by the addition of either vitamin E or catalase to the cultures."
1234516,Trevisan et al. 1998,Glutamine transaminase K intranephron localization in rats determined by urinary excretion after treatment with segment-specific nephrotoxicants,"Glutamine transaminase K(GTK) excretion assessed in urine and by kidney histology was evaluated in rats after single treatment with 1.0 mg/kg i.p. of mercuric chloride, 100 mg/kg i.p. of hexachloro-1:3-butadiene (both S3, pars recta, segment-specific nephrotoxicants) and 25 mg/kg s.c. of potassium dichromate (S1-S2, pars convoluta, segment-specific nephrotoxicant). The aim was to correlate segment-specific injury and enzyme excretion in order to assess, using non-vasive methods, localization of GTK along the proximal tubule. Mercuric chloride and hexachloro-1:3-butadiene produced early focal damage in the pars recta (focal necrosis was shown 10 h after treatment, and diffuse necrosis appeared later at 34 and 24 h after treatment). Changes of the pars convoluta were occasional and delayed (72 h after treatment for both substances). On the contrary, potassium dichromate induced damage of the pars convoluta (vacuolar degeneration and focal necrosis were evident 24 h and 48 h after treatment, respectively), whereas the pars recta was affected later (focal vacuolar degeneration was observed 72 h after treatment). Increase urinary GTK excretion was early after treatment with mercuric chloride and hexachloro-1:3-butadiene (significant increase was observed within 10 h), with a peak for both substances 24 h after treatment, in agreement with the necrosis of the pars recta. Potassium dichromate induced a significant increase of enzyme excretion in urine also 24 h after injection, according to histological features showing vacuolar degeneration of the pars convoluta; the peak of excretion was reached 48 h after treatment (delay was due, probably, to s.c. administration). The results show that GTK increased in urine after treatment with S3 and S1-S2 specific nephrotoxicants; the combination of histological examination and urinary enzyme supports the evidence that the enzyme is distributed along the whole of the proximal tubule.","Glutamine transaminase K intranephron localization in rats determined by urinary excretion after treatment with segment-specific nephrotoxicants Abs: Glutamine transaminase K(GTK) excretion assessed in urine and by kidney histology was evaluated in rats after single treatment with 1.0 mg/kg i.p. of mercuric chloride, 100 mg/kg i.p. of hexachloro-1:3-butadiene (both S3, pars recta, segment-specific nephrotoxicants) and 25 mg/kg s.c. of potassium dichromate (S1-S2, pars convoluta, segment-specific nephrotoxicant). The aim was to correlate segment-specific injury and enzyme excretion in order to assess, using non-vasive methods, localization of GTK along the proximal tubule. Mercuric chloride and hexachloro-1:3-butadiene produced early focal damage in the pars recta (focal necrosis was shown 10 h after treatment, and diffuse necrosis appeared later at 34 and 24 h after treatment). Changes of the pars convoluta were occasional and delayed (72 h after treatment for both substances). On the contrary, potassium dichromate induced damage of the pars convoluta (vacuolar degeneration and focal necrosis were evident 24 h and 48 h after treatment, respectively), whereas the pars recta was affected later (focal vacuolar degeneration was observed 72 h after treatment). Increase urinary GTK excretion was early after treatment with mercuric chloride and hexachloro-1:3-butadiene (significant increase was observed within 10 h), with a peak for both substances 24 h after treatment, in agreement with the necrosis of the pars recta. Potassium dichromate induced a significant increase of enzyme excretion in urine also 24 h after injection, according to histological features showing vacuolar degeneration of the pars convoluta; the peak of excretion was reached 48 h after treatment (delay was due, probably, to s.c. administration). The results show that GTK increased in urine after treatment with S3 and S1-S2 specific nephrotoxicants; the combination of histological examination and urinary enzyme supports the evidence that the enzyme is distributed along the whole of the proximal tubule."
1234515,Albert et al. 1998,Patch testing reactions to a standard series in 608 patients tested from 1990 to 1997 at Massachusetts General Hospital,"<strong>BACKGROUND: </strong>Patch testing is a useful diagnostic tool when allergic contact dermatitis is suspected clinically.<br /><br /><strong>OBJECTIVE: </strong>This study describes the results of patch testing performed from January 1, 1990 to June 1, 1997 at the Massachusetts General Hospital Contact Dermatitis Clinic. The findings are compared with those previously reported by the North American Contact Dermatitis Group (NACDG).<br /><br /><strong>METHODS: </strong>Data were collected from chart review and analyzed. Patients included in the study underwent patch testing to the full European standard series of allergens. A standardized patch testing technique was used, and readings were performed by a single observer.<br /><br /><strong>RESULTS: </strong>A total of 608 patients were patch tested to a screening tray of 24 allergens; 69.9% were women. At least one positive patch test reaction was observed in 60.0% of patients. The most common sensitizers were nickel sulfate, fragrance mix, potassium dichromate, cobalt chloride, balsam of Peru, quaternium-15, and neomycin sulfate. The sensitization rate to potassium dichromate (9.4%) was higher than has been reported by the NACDG. A statistically significant difference in the sensitization rate in men and women was observed for nickel, quinoline mix, epoxy resin, and formaldehyde. The prevalence of positive patch test reactions was not found to be influenced by testing during the summer months.<br /><br /><strong>CONCLUSIONS: </strong>In the authors' opinion, the prevalence of contact sensitization is generally comparable with the findings of the NACDG, with the exception of reactions to potassium dichromate. This difference in results probably reflects, in part, differences in methodology. The test concentration of potassium dichromate was 0.5%, commonly used in Europe, instead of the 0.25% concentration used by the NACDG. Further investigation is necessary to determine the optimal testing concentration of potassium dichromate.","Patch testing reactions to a standard series in 608 patients tested from 1990 to 1997 at Massachusetts General Hospital Abs: <strong>BACKGROUND: </strong>Patch testing is a useful diagnostic tool when allergic contact dermatitis is suspected clinically.<br /><br /><strong>OBJECTIVE: </strong>This study describes the results of patch testing performed from January 1, 1990 to June 1, 1997 at the Massachusetts General Hospital Contact Dermatitis Clinic. The findings are compared with those previously reported by the North American Contact Dermatitis Group (NACDG).<br /><br /><strong>METHODS: </strong>Data were collected from chart review and analyzed. Patients included in the study underwent patch testing to the full European standard series of allergens. A standardized patch testing technique was used, and readings were performed by a single observer.<br /><br /><strong>RESULTS: </strong>A total of 608 patients were patch tested to a screening tray of 24 allergens; 69.9% were women. At least one positive patch test reaction was observed in 60.0% of patients. The most common sensitizers were nickel sulfate, fragrance mix, potassium dichromate, cobalt chloride, balsam of Peru, quaternium-15, and neomycin sulfate. The sensitization rate to potassium dichromate (9.4%) was higher than has been reported by the NACDG. A statistically significant difference in the sensitization rate in men and women was observed for nickel, quinoline mix, epoxy resin, and formaldehyde. The prevalence of positive patch test reactions was not found to be influenced by testing during the summer months.<br /><br /><strong>CONCLUSIONS: </strong>In the authors' opinion, the prevalence of contact sensitization is generally comparable with the findings of the NACDG, with the exception of reactions to potassium dichromate. This difference in results probably reflects, in part, differences in methodology. The test concentration of potassium dichromate was 0.5%, commonly used in Europe, instead of the 0.25% concentration used by the NACDG. Further investigation is necessary to determine the optimal testing concentration of potassium dichromate."
1234514,Chen and  Seaton 1998,A meta-analysis of painting exposure and cancer mortality,"To assess risks of cancer mortality among workers exposed to paints, published papers referring to painters and mortality with standardized mortality ratios (SMR) were meta-analyzed in fixed and random effect models. The SMR for all sites of cancer was significantly raised (111.4; 95% CI: 105.8-117.4). The highest risks of cancer death were from leukemia (187; 95% CI: 114.5-306.7) and from liver cancer (143.6; 95% CI: 117.6-175.4). The SMRs for esophagus and stomach cancer were 132.7 (95% CI: 112.1-157.2) and 120.3 (95% CI: 111.3-130.0), respectively. The risks of bladder cancer (130.4; 95% CI: 113.8-149.5) and lung cancer (129.1; 95% CI: 119.2-139.8) were also raised. The findings provide evidence of an association between work as a painter and risk of cancer, although the confounding effects of smoking and alcohol cannot be entirely excluded, especially with respect to liver cancer since deaths from cirrhosis were also increased. The excess deaths from leukemia could have been from exposure to benzene mixed with other organic solvents, while that from lung cancer may be from exposure to particles containing lead chromate and to asbestos in the paint trade. The high risks of cirrhosis and liver cancer need to be examined further as to possible interactions between organic solvents and alcohol.","A meta-analysis of painting exposure and cancer mortality Abs: To assess risks of cancer mortality among workers exposed to paints, published papers referring to painters and mortality with standardized mortality ratios (SMR) were meta-analyzed in fixed and random effect models. The SMR for all sites of cancer was significantly raised (111.4; 95% CI: 105.8-117.4). The highest risks of cancer death were from leukemia (187; 95% CI: 114.5-306.7) and from liver cancer (143.6; 95% CI: 117.6-175.4). The SMRs for esophagus and stomach cancer were 132.7 (95% CI: 112.1-157.2) and 120.3 (95% CI: 111.3-130.0), respectively. The risks of bladder cancer (130.4; 95% CI: 113.8-149.5) and lung cancer (129.1; 95% CI: 119.2-139.8) were also raised. The findings provide evidence of an association between work as a painter and risk of cancer, although the confounding effects of smoking and alcohol cannot be entirely excluded, especially with respect to liver cancer since deaths from cirrhosis were also increased. The excess deaths from leukemia could have been from exposure to benzene mixed with other organic solvents, while that from lung cancer may be from exposure to particles containing lead chromate and to asbestos in the paint trade. The high risks of cirrhosis and liver cancer need to be examined further as to possible interactions between organic solvents and alcohol."
1234513,Klockow-Beck et al. 1998,Determination of the inorganic degradation products sulfate and sulfamate in the antiepileptic drug topiramate by capillary electrophoresis,"A capillary electrophoresis (CE) method has been developed as an alternative method for the determination of the inorganic degradation products sulfate and sulfamate in topiramate drug product and drug substance, currently performed by ion chromatography. The anions are separated in a background electrolyte containing potassium chromate and boric acid, followed by indirect UV detection. By adding tetradecyltrimethylammonium bromide to the electrolyte, analysis is performed under co-electroosmotic flow conditions. Variations in injection volumes and migration times are compensated for by use of an internal standard. The validation of the method, which was performed according to ICH guidelines (International Conference on Harmonization of Technical Requirements for Registration of Pharmaceuticals for Human Use) [1], comprises specificity, accuracy, linearity, precision, sensitivity and robustness. In addition, the results of an actual tablet sample analysis obtained by this CE method are statistically shown to be in close agreement with those obtained by an ion chromatographic method.","Determination of the inorganic degradation products sulfate and sulfamate in the antiepileptic drug topiramate by capillary electrophoresis Abs: A capillary electrophoresis (CE) method has been developed as an alternative method for the determination of the inorganic degradation products sulfate and sulfamate in topiramate drug product and drug substance, currently performed by ion chromatography. The anions are separated in a background electrolyte containing potassium chromate and boric acid, followed by indirect UV detection. By adding tetradecyltrimethylammonium bromide to the electrolyte, analysis is performed under co-electroosmotic flow conditions. Variations in injection volumes and migration times are compensated for by use of an internal standard. The validation of the method, which was performed according to ICH guidelines (International Conference on Harmonization of Technical Requirements for Registration of Pharmaceuticals for Human Use) [1], comprises specificity, accuracy, linearity, precision, sensitivity and robustness. In addition, the results of an actual tablet sample analysis obtained by this CE method are statistically shown to be in close agreement with those obtained by an ion chromatographic method."
1234511,Vanková et al. 1999,Toxicity of chromium to activated sludge,"The work deals with the toxicity of hexavalent and trivalent chromium to activated sludge. Cr(VI) was added as K2Cr2O7, and Cr(III) as Cr2(SO4)3. Toxicity is expressed as the inhibition of respiratory activity of microorganisms present in activated sludge. Respiration was measured by two methods, by means of an oximeter with an oxygen electrode and by means of a manometric apparatus permitting continuous observation of biological oxygen demand (BOD). The equation of the normal distribution function was used to construct inhibition curves and to calculate effective concentration (EC50). The influence of exposure time was observed as was the influence of concentration of activated sludge on the value of EC50. The 1-h EC50 for Cr(VI) by the ISO method was determined to be in the range of 40-90 mg/liter. A greater scatter of measured values, 46-201mg/liter, was found for the first hour of exposure by the manometric method. In the case of Cr(III) only combined inhibition by chromium ions and pH was determined. The 0.5-h EC50 was 49 mg/liter.","Toxicity of chromium to activated sludge Abs: The work deals with the toxicity of hexavalent and trivalent chromium to activated sludge. Cr(VI) was added as K2Cr2O7, and Cr(III) as Cr2(SO4)3. Toxicity is expressed as the inhibition of respiratory activity of microorganisms present in activated sludge. Respiration was measured by two methods, by means of an oximeter with an oxygen electrode and by means of a manometric apparatus permitting continuous observation of biological oxygen demand (BOD). The equation of the normal distribution function was used to construct inhibition curves and to calculate effective concentration (EC50). The influence of exposure time was observed as was the influence of concentration of activated sludge on the value of EC50. The 1-h EC50 for Cr(VI) by the ISO method was determined to be in the range of 40-90 mg/liter. A greater scatter of measured values, 46-201mg/liter, was found for the first hour of exposure by the manometric method. In the case of Cr(III) only combined inhibition by chromium ions and pH was determined. The 0.5-h EC50 was 49 mg/liter."
1234510,Liu et al. 1999,Synergistic induction of hydroxyl radical-induced DNA single-strand breaks by chromium(VI) compound and cigarette smoke solution,"Chromium(VI) compounds and cigarette smoke are known human carcinogens. We found that K2Cr2O7 and cigarette smoke solution synergistically induced DNA single-strand breaks (0.23+/-0.04 breaks per DNA molecule) in pUC118 plasmid DNA. K2Cr2O7 alone or cigarette smoke solution alone induced much less strand breaks (0.03+/-0.01 or 0.07+/-0.02 breaks per DNA molecule, respectively). The synergistic effect was prevented by catalase and by hydroxyl radical scavengers such as deferoxamine, dimethylsulfoxide, d-mannitol, and Tris, but not by superoxide dismutase. Ascorbic acid enhanced the synergism. Glutathione inhibited strand breakage only at high concentrations. Electron spin resonance (ESR) studies using a hydroxyl radical trap demonstrated that hydroxyl radicals were generated when DNA was incubated with K2Cr2O7 and cigarette smoke solution. Hydroxyl radical adduct decreased dose-dependently when strand breakage was prevented by catalase, deferoxamine, dimethylsulfoxide, d-mannitol or Tris, but not significantly by superoxide dismutase. We also used ESR spectroscopy to study the effects of different concentration of ascorbic acid and glutathione. The results showed that hydroxyl radical, which is proposed as a main carcinogenic mechanism for both chromium(VI) compounds and cigarette smoke solution was mainly responsible for the DNA breaks they induced.","Synergistic induction of hydroxyl radical-induced DNA single-strand breaks by chromium(VI) compound and cigarette smoke solution Abs: Chromium(VI) compounds and cigarette smoke are known human carcinogens. We found that K2Cr2O7 and cigarette smoke solution synergistically induced DNA single-strand breaks (0.23+/-0.04 breaks per DNA molecule) in pUC118 plasmid DNA. K2Cr2O7 alone or cigarette smoke solution alone induced much less strand breaks (0.03+/-0.01 or 0.07+/-0.02 breaks per DNA molecule, respectively). The synergistic effect was prevented by catalase and by hydroxyl radical scavengers such as deferoxamine, dimethylsulfoxide, d-mannitol, and Tris, but not by superoxide dismutase. Ascorbic acid enhanced the synergism. Glutathione inhibited strand breakage only at high concentrations. Electron spin resonance (ESR) studies using a hydroxyl radical trap demonstrated that hydroxyl radicals were generated when DNA was incubated with K2Cr2O7 and cigarette smoke solution. Hydroxyl radical adduct decreased dose-dependently when strand breakage was prevented by catalase, deferoxamine, dimethylsulfoxide, d-mannitol or Tris, but not significantly by superoxide dismutase. We also used ESR spectroscopy to study the effects of different concentration of ascorbic acid and glutathione. The results showed that hydroxyl radical, which is proposed as a main carcinogenic mechanism for both chromium(VI) compounds and cigarette smoke solution was mainly responsible for the DNA breaks they induced."
1234509,Downs and  Sansom 1999,Severe contact allergy to footwear responding to handmade shoes,,Severe contact allergy to footwear responding to handmade shoes Abs: 
1234508,Bourke et al. 1999,The reproducibility of patch tests,"There is conflicting evidence regarding the reproducibility of patch testing. Discordant results have been reported in up to 44% of cases. The clinical relevance of these discordant patch tests has not been previously assessed. We studied 383 consecutive patients receiving simultaneous duplicate patch testing on opposite sides of the upper back with 10 allergens from the European standard series. Completely discordant patch tests-a negative test on one side with a positive test on the opposite side-were recorded in 30 (8%) patients. Two patients had discordant tests to two of the allergens; 28 had discordant reactions to one allergen. Completely discordant tests were recorded for nickel in 10 (3%) patients, balsam of Peru in two (0.5%), thiomersal in one (0.3%), cobalt in four (1%), paraphenylenediamine in three (0.8%), fragrance mix in two (0.5%), formaldehyde in four (1%), potassium dichromate in two (0.5%), lanolin in three (0.8%) and Kathon CG in one (0.3%). Of those patients with completely discordant patch tests, the allergen was deemed to be a true positive in 11 (3% of total) cases and of possible relevance in a further three. The allergen was felt to be relevant to the presenting complaint in seven (2% of total) patients.","The reproducibility of patch tests Abs: There is conflicting evidence regarding the reproducibility of patch testing. Discordant results have been reported in up to 44% of cases. The clinical relevance of these discordant patch tests has not been previously assessed. We studied 383 consecutive patients receiving simultaneous duplicate patch testing on opposite sides of the upper back with 10 allergens from the European standard series. Completely discordant patch tests-a negative test on one side with a positive test on the opposite side-were recorded in 30 (8%) patients. Two patients had discordant tests to two of the allergens; 28 had discordant reactions to one allergen. Completely discordant tests were recorded for nickel in 10 (3%) patients, balsam of Peru in two (0.5%), thiomersal in one (0.3%), cobalt in four (1%), paraphenylenediamine in three (0.8%), fragrance mix in two (0.5%), formaldehyde in four (1%), potassium dichromate in two (0.5%), lanolin in three (0.8%) and Kathon CG in one (0.3%). Of those patients with completely discordant patch tests, the allergen was deemed to be a true positive in 11 (3% of total) cases and of possible relevance in a further three. The allergen was felt to be relevant to the presenting complaint in seven (2% of total) patients."
1234507,Bellegrandi et al. 1999,Contact dermatitis in subjects infected with HIV type 1,"In the course of HIV type 1 infection, up to 90% of patients may have skin disease. We studied a group of 26 HIV-infected patients (15 women, 11 men) with symptoms of skin disease or diffuse itching; they were patch tested for common contactants to determine whether allergic contact dermatitis was the cause of their symptoms. We found that approximately one third of HIV-1-positive patients with cutaneous symptoms not related to allergic contact dermatitis had positive patch tests for environmental contactants; in most of them this sensitization was directly related to skin symptoms.","Contact dermatitis in subjects infected with HIV type 1 Abs: In the course of HIV type 1 infection, up to 90% of patients may have skin disease. We studied a group of 26 HIV-infected patients (15 women, 11 men) with symptoms of skin disease or diffuse itching; they were patch tested for common contactants to determine whether allergic contact dermatitis was the cause of their symptoms. We found that approximately one third of HIV-1-positive patients with cutaneous symptoms not related to allergic contact dermatitis had positive patch tests for environmental contactants; in most of them this sensitization was directly related to skin symptoms."
1234505,Hamdan et al. 1999,Nickel subsulfide is similar to potassium dichromate in protecting normal human fibroblasts from the mutagenic effects of benzo[a]pyrene diolepoxide,"The cellular response to multiple carcinogen treatment has not been extensively studied, even though the effect of individual carcinogens is, in many cases, well known. We have previously shown that potassium dichromate can protect normal human fibroblasts from the mutagenic effects of benzo[a]pyrene diolepoxide (BPDE), and that this effect may be via an oxidative stress mechanism [Tesfai et al. (1998) Mutat Res 416:159-168]. Here, we extend our previous work by showing that nickel subsulfide can produce the some effect. Normal human fibroblasts, preincubated with nickel subsulfide for 46 hr followed by a coincubation of nickel subsulfide and BPDE for 2 hr, showed a dramatic reduction in the mutant frequency of the hypoxanthine (guanine)phosphoribosyl-transferase (HPRT) gene when compared to cells treated only with BPDE. The preincubation period with nickel subsulfide was necessary to see the antagonistic effect, since it was not observed if the cells were simply incubated with both carcinogens for 2 hr. The extent of the antagonistic effect was nickel subsulfide dose-dependent and also appeared to be species-specific, since the effect was not observed when Chinese hamster fibroblasts were tested. Finally, the antagonistic effect of the nickel subsulfide was eliminated by vitamin E, suggesting that production of reactive oxygen species by the nickel may be required. This data, along with our previous work, suggest that the antagonistic effect we observe is not chromium-specific, and that it could be species-specific.","Nickel subsulfide is similar to potassium dichromate in protecting normal human fibroblasts from the mutagenic effects of benzo[a]pyrene diolepoxide Abs: The cellular response to multiple carcinogen treatment has not been extensively studied, even though the effect of individual carcinogens is, in many cases, well known. We have previously shown that potassium dichromate can protect normal human fibroblasts from the mutagenic effects of benzo[a]pyrene diolepoxide (BPDE), and that this effect may be via an oxidative stress mechanism [Tesfai et al. (1998) Mutat Res 416:159-168]. Here, we extend our previous work by showing that nickel subsulfide can produce the some effect. Normal human fibroblasts, preincubated with nickel subsulfide for 46 hr followed by a coincubation of nickel subsulfide and BPDE for 2 hr, showed a dramatic reduction in the mutant frequency of the hypoxanthine (guanine)phosphoribosyl-transferase (HPRT) gene when compared to cells treated only with BPDE. The preincubation period with nickel subsulfide was necessary to see the antagonistic effect, since it was not observed if the cells were simply incubated with both carcinogens for 2 hr. The extent of the antagonistic effect was nickel subsulfide dose-dependent and also appeared to be species-specific, since the effect was not observed when Chinese hamster fibroblasts were tested. Finally, the antagonistic effect of the nickel subsulfide was eliminated by vitamin E, suggesting that production of reactive oxygen species by the nickel may be required. This data, along with our previous work, suggest that the antagonistic effect we observe is not chromium-specific, and that it could be species-specific."
1234504,Nakajima et al. 1999,The complete amino acid sequence of dog beta2-microglobulin,"Dog beta2-microglobulin was purified from the urine of dogs with potassium dichromate induced tubular damage. It was purified by sequential use of anion exchange chromatography, gel filtration chromatography, and reversed-phase high performance liquid chromatography. Comparisons of the amino acid sequence of the dog protein with human, mouse, and rabbit beta2-microglobulin, indicated a high degree of similarity. The dog protein was very similar to human beta2-microglobulin in that it had a molecular weight of 11.8 kDa and contained two half-cystinyl residues. Dog and human beta2-microglobulin were demonstrably different at 24 of the 99 positions compared. The data supported the conclusion that the purified protein was dog beta2-microglobulin and that all four proteins from dog, human, mouse, and rabbit were closely related.","The complete amino acid sequence of dog beta2-microglobulin Abs: Dog beta2-microglobulin was purified from the urine of dogs with potassium dichromate induced tubular damage. It was purified by sequential use of anion exchange chromatography, gel filtration chromatography, and reversed-phase high performance liquid chromatography. Comparisons of the amino acid sequence of the dog protein with human, mouse, and rabbit beta2-microglobulin, indicated a high degree of similarity. The dog protein was very similar to human beta2-microglobulin in that it had a molecular weight of 11.8 kDa and contained two half-cystinyl residues. Dog and human beta2-microglobulin were demonstrably different at 24 of the 99 positions compared. The data supported the conclusion that the purified protein was dog beta2-microglobulin and that all four proteins from dog, human, mouse, and rabbit were closely related."
1234503,Pecegueiro et al. 1999,Oral lichen planus versus oral lichenoid eruption as a manifestation of contact allergy,,Oral lichen planus versus oral lichenoid eruption as a manifestation of contact allergy Abs: 
1234502,Kohlpoth et al. 1999,Flow cytometric measurement of micronuclei induced in a permanent fish cell line as a possible screening test for the genotoxicity of industrial waste waters,"An in vitro micronucleus assay using the permanent fish cell line RTG-2 (rainbow trout gonads) was developed to test industrial waste waters for their genotoxic potential. Comparison of flow cytometric measurement and microscopic scoring of micronucleus frequency with the reference chemicals 1,4-butane sultone (0.2-1 mM), ethylmethane sulphonate (2-10 mM), potassium dichromate (20-100 microM) and benzo[a]pyrene (5-25 microM) showed similar dose-effect relationships. Thirty-eight industrial waste waters from 11 different branches of industry obtained from the Bavarian state office for water research were tested using the flow cytometric method (18 from metal processing, 10 from combined waste water, two from synthetic fibre production, one sample each from settlement wastes, non-iron metal manufacturing, leather production, sulphuric acid production, ore processing, graphite film production, cellulose production and flue gas washing). Fourteen of them showed a significant increase in micronucleus frequency.","Flow cytometric measurement of micronuclei induced in a permanent fish cell line as a possible screening test for the genotoxicity of industrial waste waters Abs: An in vitro micronucleus assay using the permanent fish cell line RTG-2 (rainbow trout gonads) was developed to test industrial waste waters for their genotoxic potential. Comparison of flow cytometric measurement and microscopic scoring of micronucleus frequency with the reference chemicals 1,4-butane sultone (0.2-1 mM), ethylmethane sulphonate (2-10 mM), potassium dichromate (20-100 microM) and benzo[a]pyrene (5-25 microM) showed similar dose-effect relationships. Thirty-eight industrial waste waters from 11 different branches of industry obtained from the Bavarian state office for water research were tested using the flow cytometric method (18 from metal processing, 10 from combined waste water, two from synthetic fibre production, one sample each from settlement wastes, non-iron metal manufacturing, leather production, sulphuric acid production, ore processing, graphite film production, cellulose production and flue gas washing). Fourteen of them showed a significant increase in micronucleus frequency."
1234501,Mancuso et al. 1999,Long-lasting allergic patch test reactions: a study of patients with positive standard patch tests,"The purpose of this study was to determine the duration of patch test reactions and the frequency of long-lasting allergic patch test reactions (LLAPTR), and to identify the possible factors related to the development of the LLAPTR. For this purpose, a group of 263 patients positive to 1 or more allergens in the GIRDCA standard series was recruited. Readings were made for each patient 2 and 3 days after patch test application and continued every 2nd and 3rd day until the disappearance of all palpable erythema. The % of LLAPTR out of the total of reactions was high: 17.9%). Kathon CG was the hapten that caused LLAPTR most frequently, with 16 cases, a frequency of 76.1%), and a mean duration of the patch test reactions of 25.4 days. Risk factors investigated were age, sex, atopy, intensity of the patch test reaction and sensitivity to some allergens with the greatest number of positive patch tests. The relative importance of each risk factor was calculated by multivariate stepwise logistic regression analysis. It was found that a Kathon CG sensitivity was the most important risk factor for LLAPTR. 2nd was atopy, followed by strong patch test reaction. Rejected risk factors were sex, age and sensitivity to nickel sulfate, potassium dichromate, Disperse Blue 124, fragrance mix and p-phenylenediamine.","Long-lasting allergic patch test reactions: a study of patients with positive standard patch tests Abs: The purpose of this study was to determine the duration of patch test reactions and the frequency of long-lasting allergic patch test reactions (LLAPTR), and to identify the possible factors related to the development of the LLAPTR. For this purpose, a group of 263 patients positive to 1 or more allergens in the GIRDCA standard series was recruited. Readings were made for each patient 2 and 3 days after patch test application and continued every 2nd and 3rd day until the disappearance of all palpable erythema. The % of LLAPTR out of the total of reactions was high: 17.9%). Kathon CG was the hapten that caused LLAPTR most frequently, with 16 cases, a frequency of 76.1%), and a mean duration of the patch test reactions of 25.4 days. Risk factors investigated were age, sex, atopy, intensity of the patch test reaction and sensitivity to some allergens with the greatest number of positive patch tests. The relative importance of each risk factor was calculated by multivariate stepwise logistic regression analysis. It was found that a Kathon CG sensitivity was the most important risk factor for LLAPTR. 2nd was atopy, followed by strong patch test reaction. Rejected risk factors were sex, age and sensitivity to nickel sulfate, potassium dichromate, Disperse Blue 124, fragrance mix and p-phenylenediamine."
1234500,Bulikowski et al. 1999,Investigations on magnesium and chromium antagonism in the skin of experimental animals,"Investigations were performed over 30 days on 25 male rats Wistar breed divided into five groups. Animals received intraperitoneally (i.p.) potassium dichromate (KDCH) 5 mg/kg (basal doses, b.d.), 2 mg/kg (0.4 b.d.) and 100 mg Mg Cl2/kg body weight (b.w.). In performed investigations the highest concentration of chromium in animal skin 1.17 +/- 0.11 micrograms/g was observed by i.p. administration of KDCH 5 mg/kg b.w. Simultaneous i.p. administration of KDCH 5 mg/kg b.w. and MgCl2 100 mg/kg b.w. resulted in significant lower concentration of chromium (in comparison to the preceding group) in animal skin: 0.8 +/- 0.2 microgram/g (p < 0.001). In i.p. administration of KDCH in the doses of 0.4 b.d. the concentration of Cr in the skin amounted to 0.55 +/- 0.1 microgram/g. Values of Cr in the skin in exposed groups were significantly higher than in the control group, (p < 0.001).","Investigations on magnesium and chromium antagonism in the skin of experimental animals Abs: Investigations were performed over 30 days on 25 male rats Wistar breed divided into five groups. Animals received intraperitoneally (i.p.) potassium dichromate (KDCH) 5 mg/kg (basal doses, b.d.), 2 mg/kg (0.4 b.d.) and 100 mg Mg Cl2/kg body weight (b.w.). In performed investigations the highest concentration of chromium in animal skin 1.17 +/- 0.11 micrograms/g was observed by i.p. administration of KDCH 5 mg/kg b.w. Simultaneous i.p. administration of KDCH 5 mg/kg b.w. and MgCl2 100 mg/kg b.w. resulted in significant lower concentration of chromium (in comparison to the preceding group) in animal skin: 0.8 +/- 0.2 microgram/g (p < 0.001). In i.p. administration of KDCH in the doses of 0.4 b.d. the concentration of Cr in the skin amounted to 0.55 +/- 0.1 microgram/g. Values of Cr in the skin in exposed groups were significantly higher than in the control group, (p < 0.001)."
1234499,Courtheyn et al. 1998,Determination of betamethasone and triamcinolone acetonide by GC-NCI-MS in excreta of treated animals and development of a fast oxidation procedure for derivatisation of corticosteroids,"The use of corticosteroids in combination with other hormonal substances has long been known to result in increased mass gain with bovines. Practice has demonstrated, however, that even the single use of a glucocorticoid may result in growth promoting effects. In addition to the popular dexamethasone, more recently other corticosteroids have also been misused for fattening purposes. The first part of this study deals with the detection of two of them, namely betamethasone and triamcinolone acetonide. Betamethasone was administered orally to a cow at a dose of 50 mg d-1 for 5 d, then later the same cow was injected intramuscularly with a dose of 50 mg of betamethasone dipropionate. Excretion in urine and faeces was followed with both HPLC-enzyme immunoassay and a previously described method based on negative chemical ionization mass spectrometry (NCI-MS) after oxidation. For the triamcinolone acetonide study a cow was treated with 50 mg d-1 of the drug during a 7 d period. Excretion in faeces was followed with GC-NCI-MS. As triamcinolone acetonide is resistant to the previously described oxidation procedure, however, a hydrolysis step had to be introduced prior to oxidation. In addition to this specific modification necessary for triamcinolone acetonide, in a subsequent part of this study the original oxidation procedure with pyridinium chlorochromate was re-investigated especially to shorten the procedure. With the introduction of potassium dichromate the reaction time could be decreased from 3 h to 10 min.","Determination of betamethasone and triamcinolone acetonide by GC-NCI-MS in excreta of treated animals and development of a fast oxidation procedure for derivatisation of corticosteroids Abs: The use of corticosteroids in combination with other hormonal substances has long been known to result in increased mass gain with bovines. Practice has demonstrated, however, that even the single use of a glucocorticoid may result in growth promoting effects. In addition to the popular dexamethasone, more recently other corticosteroids have also been misused for fattening purposes. The first part of this study deals with the detection of two of them, namely betamethasone and triamcinolone acetonide. Betamethasone was administered orally to a cow at a dose of 50 mg d-1 for 5 d, then later the same cow was injected intramuscularly with a dose of 50 mg of betamethasone dipropionate. Excretion in urine and faeces was followed with both HPLC-enzyme immunoassay and a previously described method based on negative chemical ionization mass spectrometry (NCI-MS) after oxidation. For the triamcinolone acetonide study a cow was treated with 50 mg d-1 of the drug during a 7 d period. Excretion in faeces was followed with GC-NCI-MS. As triamcinolone acetonide is resistant to the previously described oxidation procedure, however, a hydrolysis step had to be introduced prior to oxidation. In addition to this specific modification necessary for triamcinolone acetonide, in a subsequent part of this study the original oxidation procedure with pyridinium chlorochromate was re-investigated especially to shorten the procedure. With the introduction of potassium dichromate the reaction time could be decreased from 3 h to 10 min."
1234498,Fernandes et al. 1998,"Human cyclosporiasis diagnosis: report of a case in São Paulo, SP, Brazil","Diagnosis of the human cyclosporiasis is reported in São Paulo, SP, Brasil. Cyclospora cayetanensis has been identified in the feces of a patient by a modified Kinyoun staining method, with later sporulation in a solution of 2.5% potassium dichromate. The probability that this parasite is the eventual cause of gastrointestinal disturbances in the country was stimulated by this finding, which was arrived at by a simple technique. It had been kept in mind that the disease was expressing itself mainly among immunocompromised patients, whose number is increasing; especially in those with acquired immunodeficiency syndrome (AIDS), which is caused by the human immunodeficiency virus (HIV).","Human cyclosporiasis diagnosis: report of a case in São Paulo, SP, Brazil Abs: Diagnosis of the human cyclosporiasis is reported in São Paulo, SP, Brasil. Cyclospora cayetanensis has been identified in the feces of a patient by a modified Kinyoun staining method, with later sporulation in a solution of 2.5% potassium dichromate. The probability that this parasite is the eventual cause of gastrointestinal disturbances in the country was stimulated by this finding, which was arrived at by a simple technique. It had been kept in mind that the disease was expressing itself mainly among immunocompromised patients, whose number is increasing; especially in those with acquired immunodeficiency syndrome (AIDS), which is caused by the human immunodeficiency virus (HIV)."
1234497,Nakajima et al. 1999,Determination of bovine beta2-microglobulin and albumin in urine by a reversed-phase high-performance liquid chromatography,"Reversed-phase high-performance liquid chromatography (HPLC) was used to analyze beta2-microglobulin and albumin in bovine urine. The urine samples were chromatographed on TSK-gel ODS-120T column with an acetonitrile gradient. Urinary beta2-m and albumin were detected at 220 nm. For the pre-treatment, there were two steps proceeding injection: dialysis of urine with distilled water overnight, followed by concentration by solid-phase extraction method using a Sep-Pak cartridge. The retention times of beta2-microglobulin and albumin were 25.35 +/- 0.85 and 32.20 +/- 0.20 minutes (n=5), respectively. The mean analytical recoveries of beta2-microglobulin and albumin added to 0.1 ml of urine samples were 94.5 and 100.5%, respectively. The within-run coefficients of variation ranged from 1.5 to 5.3% for beta2-microglobulin and from 2.3 to 7.0% for albumin. The sensitivity for quantification of each protein was 0.5 microg in 100 microl injected urine samples. Urine samples from healthy cows and from cows with different types of proteinuria were analyzed by this reversed-phase HPLC. Results revealed albumin was remarkable in the urine from a cow with glomerulonephritis, and beta2-microglobulin was, in the urine from a cow with tubular dysfunction.","Determination of bovine beta2-microglobulin and albumin in urine by a reversed-phase high-performance liquid chromatography Abs: Reversed-phase high-performance liquid chromatography (HPLC) was used to analyze beta2-microglobulin and albumin in bovine urine. The urine samples were chromatographed on TSK-gel ODS-120T column with an acetonitrile gradient. Urinary beta2-m and albumin were detected at 220 nm. For the pre-treatment, there were two steps proceeding injection: dialysis of urine with distilled water overnight, followed by concentration by solid-phase extraction method using a Sep-Pak cartridge. The retention times of beta2-microglobulin and albumin were 25.35 +/- 0.85 and 32.20 +/- 0.20 minutes (n=5), respectively. The mean analytical recoveries of beta2-microglobulin and albumin added to 0.1 ml of urine samples were 94.5 and 100.5%, respectively. The within-run coefficients of variation ranged from 1.5 to 5.3% for beta2-microglobulin and from 2.3 to 7.0% for albumin. The sensitivity for quantification of each protein was 0.5 microg in 100 microl injected urine samples. Urine samples from healthy cows and from cows with different types of proteinuria were analyzed by this reversed-phase HPLC. Results revealed albumin was remarkable in the urine from a cow with glomerulonephritis, and beta2-microglobulin was, in the urine from a cow with tubular dysfunction."
1234496,Amrani et al. 1999,"Genotoxic activity of different chromium compounds in larval cells of Drosophila melanogaster, as measured in the wing spot test","Two chromium(VI) compounds (potassium chromate and potassium dichromate) and one chromium(III) compound, chromium chloride, were evaluated for genotoxic effects in the wing spot test of Drosophila melanogaster following standard procedures. This assay detects both somatic recombination and mutational events. The genotoxic effects were determined from the appearance of wing spots in flies transheterozygous for the third chromosome recessive markers multiple wing hairs (mwh) and flare-3 (flr(3)), as well as in flies heterozygous formwh and the multiply inverted TM3 balancer chromosome. Genetic changes induced in somatic cells of the wing's imaginal discs lead to the formation of mutant clones on the wingblade. Single spots are due to different genotoxic mechanisms: point mutation, deletion, chromosome breakage, and mitotic recombination; while twin spots are produced only by mitotic recombination. From our results it appears that both chromium(VI) compounds clearly increase the incidence of mutant clones by inducing high increases in the frequency of all types of clones recorded. On the contrary, chromium(III) did not increase the frequency of mutant clones. A high proportion of the total spot induction was due to mitotic recombination, confirming previously reported data on the strong recombinogenic activity of chromium(VI) compounds.","Genotoxic activity of different chromium compounds in larval cells of Drosophila melanogaster, as measured in the wing spot test Abs: Two chromium(VI) compounds (potassium chromate and potassium dichromate) and one chromium(III) compound, chromium chloride, were evaluated for genotoxic effects in the wing spot test of Drosophila melanogaster following standard procedures. This assay detects both somatic recombination and mutational events. The genotoxic effects were determined from the appearance of wing spots in flies transheterozygous for the third chromosome recessive markers multiple wing hairs (mwh) and flare-3 (flr(3)), as well as in flies heterozygous formwh and the multiply inverted TM3 balancer chromosome. Genetic changes induced in somatic cells of the wing's imaginal discs lead to the formation of mutant clones on the wingblade. Single spots are due to different genotoxic mechanisms: point mutation, deletion, chromosome breakage, and mitotic recombination; while twin spots are produced only by mitotic recombination. From our results it appears that both chromium(VI) compounds clearly increase the incidence of mutant clones by inducing high increases in the frequency of all types of clones recorded. On the contrary, chromium(III) did not increase the frequency of mutant clones. A high proportion of the total spot induction was due to mitotic recombination, confirming previously reported data on the strong recombinogenic activity of chromium(VI) compounds."
1234495,López et al. 1999,Influence of river water in the detection of Cr(VI) mutagenicity by the Ames test,,Influence of river water in the detection of Cr(VI) mutagenicity by the Ames test Abs: 
1234494,Wahlkvist et al. 1999,Dose-response studies of contact allergens using 3 guinea pigs models,"A multi-dose-response induction protocol for the guinea pig maximization test (GPMT), including a statistical computer program, has earlier been developed to improve the power of predictive tests for identification of contact allergens. This dose-response protocol, with 2 modifications (i.e., increased number of animals in each group and increased number of challenge concentrations) was evaluated in the GPMT, the cumulative contact enhancement test (CCET) and the Freund's complete adjuvant test (FCAT), using potassium dichromate and hydroxycitronellal as model contact allergens. Application of the dose-response protocol on the CCET and the FCAT resulted in either monotone or non-monotone curves with significant dose-response. However, application of the dose-response protocol on the GPMT gave curves with no significant dose-response. The protocol makes it possible to obtain an EC50 value, thus improving the possibility of ranking contact allergens, which is of substantial use for risk assessments. The dose-response protocol could benefit from a few adjustments: a wider span in the induction doses; change to simultaneous increase in intradermal and topical induction doses to obtain a proper dose-response for the GPMT; the addition of further challenge concentrations. In addition the computer program should allow calculation of threshold concentration for sensitization and EC50 value for a non-monotone curve.","Dose-response studies of contact allergens using 3 guinea pigs models Abs: A multi-dose-response induction protocol for the guinea pig maximization test (GPMT), including a statistical computer program, has earlier been developed to improve the power of predictive tests for identification of contact allergens. This dose-response protocol, with 2 modifications (i.e., increased number of animals in each group and increased number of challenge concentrations) was evaluated in the GPMT, the cumulative contact enhancement test (CCET) and the Freund's complete adjuvant test (FCAT), using potassium dichromate and hydroxycitronellal as model contact allergens. Application of the dose-response protocol on the CCET and the FCAT resulted in either monotone or non-monotone curves with significant dose-response. However, application of the dose-response protocol on the GPMT gave curves with no significant dose-response. The protocol makes it possible to obtain an EC50 value, thus improving the possibility of ranking contact allergens, which is of substantial use for risk assessments. The dose-response protocol could benefit from a few adjustments: a wider span in the induction doses; change to simultaneous increase in intradermal and topical induction doses to obtain a proper dose-response for the GPMT; the addition of further challenge concentrations. In addition the computer program should allow calculation of threshold concentration for sensitization and EC50 value for a non-monotone curve."
1234493,Adler 1999,Efficacy and safety of a fixed-combination homeopathic therapy for sinusitis,"The efficacy and safety of a fixed-combination homeopathic medication (Sinusitis PMD) consisting of Lobaria pulmonaria, Luffa operculata, and potassium dichromate were investigated in an open-label practice-based study of 119 male and female patients, 12 to 57 years of age, with clinical signs of acute sinusitis not previously treated. At the first visit, after a mean of 4.1 days of treatment, secretolysis had increased significantly and typical sinusitis symptoms, such as headache, pressure pain at nerve exit points, and irritating cough, were reduced. Ninety-nine patients received only the test medication. Twenty patients were able to discontinue concomitant medication at the first visit. Only one patient needed an antibiotic. The average treatment duration was 2 weeks. At the end of treatment, 81.5% of patients described themselves as symptom free or significantly improved. Adverse drug effects were not reported.","Efficacy and safety of a fixed-combination homeopathic therapy for sinusitis Abs: The efficacy and safety of a fixed-combination homeopathic medication (Sinusitis PMD) consisting of Lobaria pulmonaria, Luffa operculata, and potassium dichromate were investigated in an open-label practice-based study of 119 male and female patients, 12 to 57 years of age, with clinical signs of acute sinusitis not previously treated. At the first visit, after a mean of 4.1 days of treatment, secretolysis had increased significantly and typical sinusitis symptoms, such as headache, pressure pain at nerve exit points, and irritating cough, were reduced. Ninety-nine patients received only the test medication. Twenty patients were able to discontinue concomitant medication at the first visit. Only one patient needed an antibiotic. The average treatment duration was 2 weeks. At the end of treatment, 81.5% of patients described themselves as symptom free or significantly improved. Adverse drug effects were not reported."
1234492,Woods et al. 1999,The role of glutathione in chronic adaptation to oxidative stress: studies in a normal rat kidney epithelial (NRK52E) cell model of sustained upregulation of glutathione biosynthesis,"Reduced glutathione (GSH) is considered to play a central role in protection of cells from oxidant injury. However, the question remains as to whether sustained elevation of intracellular GSH levels, as compared with the ability to rapidly upregulate GSH synthesis, is more important with respect to protection of cell constituents from oxidative stress. To address this question, we conducted studies to evaluate the direct influence of chronically increased endogenous GSH content on chemically induced intracellular free radical formation and oxidative stress using a kidney epithelial cell model adapted to sustain intracellular GSH concentrations in excess of eightfold that observed in unadapted parent kidney cells. Elevated GSH levels in adapted cells were found to be attributable, at least in part, to coordinately increased amounts of both the regulatory and catalytic subunits of gamma-glutamylcysteine synthetase (GCS), the rate-limiting enzyme in GSH synthesis. Studies using electron spin resonance (ESR) spectroscopy and scanning laser cytometry demonstrated that cells having sustained elevation of GSH levels did not attenuate free radical formation and associated oxidative stress compared with parent cells when treated with the prooxidant chemicals, menadione or potassium dichromate. In contrast, nonadapted kidney parent cells treated 18 h after initial prooxidant challenge displayed significantly attenuated free radical signals. Additionally, cells adapted to sustain excess GSH were somewhat more sensitive than parent cells in terms of resistance to prooxidant (chromate) toxicity, as determined by cell viability assays. These findings suggest that the capacity of cells to rapidly upregulate GSH synthesis, rather the ability to chronically sustain elevated intracellular GSH levels, may play a more important role in terms of protection from cytotoxicity associated with prooxidant chemical exposures.","The role of glutathione in chronic adaptation to oxidative stress: studies in a normal rat kidney epithelial (NRK52E) cell model of sustained upregulation of glutathione biosynthesis Abs: Reduced glutathione (GSH) is considered to play a central role in protection of cells from oxidant injury. However, the question remains as to whether sustained elevation of intracellular GSH levels, as compared with the ability to rapidly upregulate GSH synthesis, is more important with respect to protection of cell constituents from oxidative stress. To address this question, we conducted studies to evaluate the direct influence of chronically increased endogenous GSH content on chemically induced intracellular free radical formation and oxidative stress using a kidney epithelial cell model adapted to sustain intracellular GSH concentrations in excess of eightfold that observed in unadapted parent kidney cells. Elevated GSH levels in adapted cells were found to be attributable, at least in part, to coordinately increased amounts of both the regulatory and catalytic subunits of gamma-glutamylcysteine synthetase (GCS), the rate-limiting enzyme in GSH synthesis. Studies using electron spin resonance (ESR) spectroscopy and scanning laser cytometry demonstrated that cells having sustained elevation of GSH levels did not attenuate free radical formation and associated oxidative stress compared with parent cells when treated with the prooxidant chemicals, menadione or potassium dichromate. In contrast, nonadapted kidney parent cells treated 18 h after initial prooxidant challenge displayed significantly attenuated free radical signals. Additionally, cells adapted to sustain excess GSH were somewhat more sensitive than parent cells in terms of resistance to prooxidant (chromate) toxicity, as determined by cell viability assays. These findings suggest that the capacity of cells to rapidly upregulate GSH synthesis, rather the ability to chronically sustain elevated intracellular GSH levels, may play a more important role in terms of protection from cytotoxicity associated with prooxidant chemical exposures."
1234491,Belagyi et al. 1999,Effect of hexavalent chromium on eukaryotic plasma membrane studied by EPR spectroscopy,"The effect of Cr(VI) anion on an ergosterol-producing strain of eukaryotic yeast Candida albicans and its mutant with ergosterol-less membrane was studied with EPR spectroscopy. 5- and 14-doxyl stearic acid spin probes were used to label the protoplast membrane after removal of the cell wall. In control experiments, the mutant strain exhibited larger rigidity in the membrane than its parental strain. Addition of Cr(VI), at a minimum inhibitory concentration of 0.6 mM, increased the rotational mobility of the spin labels significantly and decreased the temperature of the structural changes in both strains, in the temperature range between 0 and 30 degrees C. The ergosterol-less mutant, having a membrane composition with increased polyunsaturated fatty acid content, exhibited higher Cr(VI) sensitivity. Treatment of the membrane with Cr(VI) for 10 min already resulted in an increase in membrane fluidity. An EPR signal of Cr(V) was detected which reached maximum amplitude after 120 min of treatment with Cr(VI). Further chemical reduction of Cr(V) in the absence of extracellular Cr(VI) led to a lack of detectable paramagnetic chromium intermediates within 200 min.","Effect of hexavalent chromium on eukaryotic plasma membrane studied by EPR spectroscopy Abs: The effect of Cr(VI) anion on an ergosterol-producing strain of eukaryotic yeast Candida albicans and its mutant with ergosterol-less membrane was studied with EPR spectroscopy. 5- and 14-doxyl stearic acid spin probes were used to label the protoplast membrane after removal of the cell wall. In control experiments, the mutant strain exhibited larger rigidity in the membrane than its parental strain. Addition of Cr(VI), at a minimum inhibitory concentration of 0.6 mM, increased the rotational mobility of the spin labels significantly and decreased the temperature of the structural changes in both strains, in the temperature range between 0 and 30 degrees C. The ergosterol-less mutant, having a membrane composition with increased polyunsaturated fatty acid content, exhibited higher Cr(VI) sensitivity. Treatment of the membrane with Cr(VI) for 10 min already resulted in an increase in membrane fluidity. An EPR signal of Cr(V) was detected which reached maximum amplitude after 120 min of treatment with Cr(VI). Further chemical reduction of Cr(V) in the absence of extracellular Cr(VI) led to a lack of detectable paramagnetic chromium intermediates within 200 min."
1234490,Flores and  Pérez 1999,"Cytotoxicity, apoptosis, and in vitro DNA damage induced by potassium chromate","Cr(6+) is a known human cytotoxic and carcinogenic agent that requires intracellular reduction for activation. We have analyzed the cytotoxic and DNA binding properties of K(2)CrO(4) (Cr(6+)) in comparison with those of Cl(3)Cr (Cr(3+)). The results indicate that K(2)CrO(4) exhibits higher cytotoxicity than Cl(3)Cr in several human and murine cell lines. The cytotoxic activity of K(2)CrO(4) is also indicated by the fact that is able to produce cell killing through apoptosis in cisplatin-resistant cells transformed by H-ras oncogene. Moreover, in vitro DNA binding experiments show that, in the presence of ascorbate (the major intracellular reductant of Cr(6+)), K(2)CrO(4) induces both interstrand cross-links and strand breaks. Because the chromate anion is by itself unreactive toward DNA, these data suggest that the cytotoxicity of K(2)CrO(4) may be associated with the DNA binding of reactive intermediate chromium species resulting from reduction of Cr(6+).","Cytotoxicity, apoptosis, and in vitro DNA damage induced by potassium chromate Abs: Cr(6+) is a known human cytotoxic and carcinogenic agent that requires intracellular reduction for activation. We have analyzed the cytotoxic and DNA binding properties of K(2)CrO(4) (Cr(6+)) in comparison with those of Cl(3)Cr (Cr(3+)). The results indicate that K(2)CrO(4) exhibits higher cytotoxicity than Cl(3)Cr in several human and murine cell lines. The cytotoxic activity of K(2)CrO(4) is also indicated by the fact that is able to produce cell killing through apoptosis in cisplatin-resistant cells transformed by H-ras oncogene. Moreover, in vitro DNA binding experiments show that, in the presence of ascorbate (the major intracellular reductant of Cr(6+)), K(2)CrO(4) induces both interstrand cross-links and strand breaks. Because the chromate anion is by itself unreactive toward DNA, these data suggest that the cytotoxicity of K(2)CrO(4) may be associated with the DNA binding of reactive intermediate chromium species resulting from reduction of Cr(6+)."
1234489,Ko?aci?ski et al. 1999,Acute potassium dichromate poisoning: a toxicokinetic case study,"CASE REPORT: A 48-year-old man drank 150 mL of an aqueous solution containing potassium dichromate 22.5 g in a suicidal attempt and was admitted 7 hours after the ingestion. Hemodialysis was promptly undertaken and chromium concentrations in serum, erythrocytes, and dialysate were determined during the treatment. Chromium elimination in urine was monitored during hemodialysis and the subsequent 400 hours. The total chromium eliminated via hemodialysis and urine was calculated as 36.7 mg or 0.16% of the ingested dose. Spontaneous urinary elimination proceeded according to an open one-compartment model. The elimination half-life was 71.37 hours +/- 17.13 hours (95% CI). Chromium elimination from serum followed an open two-compartment model, with the half-lives of 3.16 hours +/- 2.63 hours for phase 1 and 50 hours +/- 27 hours (95% CI) for phase 2. Calcium-EDTA therapy had no influence on erythrocyte, serum, or urine chromium level. It contributed, however, to a significant increase in chromium elimination rate in the dialysate. Serum zinc was very low at admission and serum zinc, copper, and magnesium were controlled during the initial 30 hours.","Acute potassium dichromate poisoning: a toxicokinetic case study Abs: CASE REPORT: A 48-year-old man drank 150 mL of an aqueous solution containing potassium dichromate 22.5 g in a suicidal attempt and was admitted 7 hours after the ingestion. Hemodialysis was promptly undertaken and chromium concentrations in serum, erythrocytes, and dialysate were determined during the treatment. Chromium elimination in urine was monitored during hemodialysis and the subsequent 400 hours. The total chromium eliminated via hemodialysis and urine was calculated as 36.7 mg or 0.16% of the ingested dose. Spontaneous urinary elimination proceeded according to an open one-compartment model. The elimination half-life was 71.37 hours +/- 17.13 hours (95% CI). Chromium elimination from serum followed an open two-compartment model, with the half-lives of 3.16 hours +/- 2.63 hours for phase 1 and 50 hours +/- 27 hours (95% CI) for phase 2. Calcium-EDTA therapy had no influence on erythrocyte, serum, or urine chromium level. It contributed, however, to a significant increase in chromium elimination rate in the dialysate. Serum zinc was very low at admission and serum zinc, copper, and magnesium were controlled during the initial 30 hours."
1234488,Albert et al. 1999,Concomitant positive reactions to allergens in a patch testing standard series from 1988-1997,"<strong>BACKGROUND: </strong>Patch testing is a useful diagnostic technique in patients with suspected allergic contact dermatitis (ACD). Concomitant reactions may reflect associations between tested allergens.<br /><br /><strong>OBJECTIVE: </strong>This study was performed to identify positive correlations between reactions to test substances in a standard screening series. The results of patch testing in patients seen from 1988 to 1997 are described.<br /><br /><strong>METHODS: </strong>Data were collected from chart review for patients who underwent patch testing to the full standard screening series at the Massachusetts General Hospital Contact Dermatitis Clinic. The Fisher exact test was used to evaluate associations between allergens.<br /><br /><strong>RESULTS: </strong>A total of 927 patients were patch tested to 22 allergens included in a screening tray. The mean age was 43.9 years, and 68.6% were women. Two or more positive reactions occurred in 36.5% of patients. Reactions to 13 pairs of allergens were found to be significantly correlated: balsam of Peru/fragrance mix, carba mix/thiuram mix, carba mix/paraben mix, cobalt chloride/potassium dichromate, cobalt chloride/nickel sulfate, ethylenediamine/neomycin sulfate, formaldehyde/imidazolidinyl urea, formaldehyde/paraben mix, formaldehyde/quaternium-15, imidazolidinyl urea/quaternium-15, neomycin sulfate/potassium dichromate, paraben mix/quaternium-15, and potassium dichromate/thimerosal.<br /><br /><strong>CONCLUSION: </strong>Concomitant reactions to 13 pairs of allergens in a standard series occurred at a rate greater than would be predicted by chance. Such associations may reflect cross-sensitization or cosensitization.","Concomitant positive reactions to allergens in a patch testing standard series from 1988-1997 Abs: <strong>BACKGROUND: </strong>Patch testing is a useful diagnostic technique in patients with suspected allergic contact dermatitis (ACD). Concomitant reactions may reflect associations between tested allergens.<br /><br /><strong>OBJECTIVE: </strong>This study was performed to identify positive correlations between reactions to test substances in a standard screening series. The results of patch testing in patients seen from 1988 to 1997 are described.<br /><br /><strong>METHODS: </strong>Data were collected from chart review for patients who underwent patch testing to the full standard screening series at the Massachusetts General Hospital Contact Dermatitis Clinic. The Fisher exact test was used to evaluate associations between allergens.<br /><br /><strong>RESULTS: </strong>A total of 927 patients were patch tested to 22 allergens included in a screening tray. The mean age was 43.9 years, and 68.6% were women. Two or more positive reactions occurred in 36.5% of patients. Reactions to 13 pairs of allergens were found to be significantly correlated: balsam of Peru/fragrance mix, carba mix/thiuram mix, carba mix/paraben mix, cobalt chloride/potassium dichromate, cobalt chloride/nickel sulfate, ethylenediamine/neomycin sulfate, formaldehyde/imidazolidinyl urea, formaldehyde/paraben mix, formaldehyde/quaternium-15, imidazolidinyl urea/quaternium-15, neomycin sulfate/potassium dichromate, paraben mix/quaternium-15, and potassium dichromate/thimerosal.<br /><br /><strong>CONCLUSION: </strong>Concomitant reactions to 13 pairs of allergens in a standard series occurred at a rate greater than would be predicted by chance. Such associations may reflect cross-sensitization or cosensitization."
1234487,Guermant et al. 2000,"Under proper control, oxidation of proteins with known chemical structure provides an accurate and absolute method for the determination of their molar concentration","Oxidation at 120 degrees C of inorganic and organic (including amino acids, di- and tripeptides) model compounds by K(2)Cr(2)O(7) in the presence of H(2)SO(4) (mass fraction: 0.572), Ag(2)SO(4) (catalyst), and HgSO(4) results in the quantitative conversion of their C-atoms into CO(2) within 24 h or less. Under these stressed, well-defined conditions, the S-atoms present in cysteine and cystine residues are oxidized into SO(3) while, interestingly, the oxidation states of all the other (including the N-) atoms normally present in a protein do remain quite unchanged. When the chemical structure of a given protein is available, the total number of electrons the protein is able to transfer to K(2)Cr(2)O(7) and thereof, the total number of moles of Cr(3+) ions which the protein is able to generate upon oxidation can be accurately calculated. In such cases, unknown protein molar concentrations can thus be determined through straightforward spectrophotometric measurements of Cr(3+) concentrations. The values of molar absorption coefficients for several well-characterized proteins have been redetermined on this basis and observed to be in excellent agreement with the most precise values reported in the literature, which fully assesses the validity of the method. When applied to highly purified proteins of known chemical structure (more generally of known atomic composition), this method is absolute and accurate (+/-1%). Furthermore, it is well adapted to series measurements since available commercial kits for chemical oxygen demand (COD) measurements can readily be adapted to work under the experimental conditions recommended here for the protein assay.","Under proper control, oxidation of proteins with known chemical structure provides an accurate and absolute method for the determination of their molar concentration Abs: Oxidation at 120 degrees C of inorganic and organic (including amino acids, di- and tripeptides) model compounds by K(2)Cr(2)O(7) in the presence of H(2)SO(4) (mass fraction: 0.572), Ag(2)SO(4) (catalyst), and HgSO(4) results in the quantitative conversion of their C-atoms into CO(2) within 24 h or less. Under these stressed, well-defined conditions, the S-atoms present in cysteine and cystine residues are oxidized into SO(3) while, interestingly, the oxidation states of all the other (including the N-) atoms normally present in a protein do remain quite unchanged. When the chemical structure of a given protein is available, the total number of electrons the protein is able to transfer to K(2)Cr(2)O(7) and thereof, the total number of moles of Cr(3+) ions which the protein is able to generate upon oxidation can be accurately calculated. In such cases, unknown protein molar concentrations can thus be determined through straightforward spectrophotometric measurements of Cr(3+) concentrations. The values of molar absorption coefficients for several well-characterized proteins have been redetermined on this basis and observed to be in excellent agreement with the most precise values reported in the literature, which fully assesses the validity of the method. When applied to highly purified proteins of known chemical structure (more generally of known atomic composition), this method is absolute and accurate (+/-1%). Furthermore, it is well adapted to series measurements since available commercial kits for chemical oxygen demand (COD) measurements can readily be adapted to work under the experimental conditions recommended here for the protein assay."
1234485,Nota et al. 2000,Reducing phosphine after the smoking process using an oxidative treatment,"This article gives a description of the setup in a laboratory of a pilot system to reduce phosphine following the smoking process of foodstuffs. At present, this fumigant is released into the atmosphere and causes serious damage to the environment due to its transformation into aggressive compounds. However, phosphine may prove a good alternative to methyl bromide, which will legally be used as a fumigant until the year 2002, provided it is made inert after the smoking process and transformed into nontoxic and easily disposable substances. Oxidant solutions containing potassium permanganate or potassium bichromate in suitable concentrations proved moderately effective in reducing phosphine. The addition of traces of silver nitrate as a catalyst to the oxidant solutions increased the efficiency in reducing the fumigant, although not completely. Thus it was necessary to use a recycling system to decontaminate air from phosphine, as such an apparatus ensures the complete reduction of phosphine. The mathematical function describing how the concentration of phosphine varies in the smoking chamber also makes it possible to estimate the time necessary to reduce a phosphine concentration from any initial value to a fixed final value.","Reducing phosphine after the smoking process using an oxidative treatment Abs: This article gives a description of the setup in a laboratory of a pilot system to reduce phosphine following the smoking process of foodstuffs. At present, this fumigant is released into the atmosphere and causes serious damage to the environment due to its transformation into aggressive compounds. However, phosphine may prove a good alternative to methyl bromide, which will legally be used as a fumigant until the year 2002, provided it is made inert after the smoking process and transformed into nontoxic and easily disposable substances. Oxidant solutions containing potassium permanganate or potassium bichromate in suitable concentrations proved moderately effective in reducing phosphine. The addition of traces of silver nitrate as a catalyst to the oxidant solutions increased the efficiency in reducing the fumigant, although not completely. Thus it was necessary to use a recycling system to decontaminate air from phosphine, as such an apparatus ensures the complete reduction of phosphine. The mathematical function describing how the concentration of phosphine varies in the smoking chamber also makes it possible to estimate the time necessary to reduce a phosphine concentration from any initial value to a fixed final value."
1234484,Sherchand et al. 1999,"Study of Cyclospora cayetanensis in health care facilities, sewage water and green leafy vegetables in Nepal","Cyclospora cayetanensis, a newly emerging parasite, is endemic in Nepal. A total of 2,123 stool specimens were collected from 3 health care facilities based on clinical symptoms during the period between 1995 to October, 1998. Out of these specimens, cayetanensis oocysts were found in 632 (29.8%). To identify possible sources for Cyclospora infection, drinking water, sewage water, green-leafy vegetables including fecal samples of various animals were collected and examined. The vegetable leaves were washed in distilled water then the washings, sewage water and drinking water were centrifuged and the sediment were examined microscopically. As a result, oocyst of Cyclospora were identified in sewage water and vegetable washings on four different occasions in June, August, October and November. The positive results were also confirmed as C. cayetanensis by development of 2 sporocysts after 2 week incubation period in potassium dichromate. A survey of 196 domestic animals from the same areas demonstrated that two chickens were positive for Cyclospora-like organism and others were negative. Although further studies are needed to clarify the direct link between Cyclospora infection and these sources, the results suggest that sewage water, green leafy vegetables are possible sources of infection and chickens could be possible reservoir host of Cyclospora in Nepal.","Study of Cyclospora cayetanensis in health care facilities, sewage water and green leafy vegetables in Nepal Abs: Cyclospora cayetanensis, a newly emerging parasite, is endemic in Nepal. A total of 2,123 stool specimens were collected from 3 health care facilities based on clinical symptoms during the period between 1995 to October, 1998. Out of these specimens, cayetanensis oocysts were found in 632 (29.8%). To identify possible sources for Cyclospora infection, drinking water, sewage water, green-leafy vegetables including fecal samples of various animals were collected and examined. The vegetable leaves were washed in distilled water then the washings, sewage water and drinking water were centrifuged and the sediment were examined microscopically. As a result, oocyst of Cyclospora were identified in sewage water and vegetable washings on four different occasions in June, August, October and November. The positive results were also confirmed as C. cayetanensis by development of 2 sporocysts after 2 week incubation period in potassium dichromate. A survey of 196 domestic animals from the same areas demonstrated that two chickens were positive for Cyclospora-like organism and others were negative. Although further studies are needed to clarify the direct link between Cyclospora infection and these sources, the results suggest that sewage water, green leafy vegetables are possible sources of infection and chickens could be possible reservoir host of Cyclospora in Nepal."
1234483,Koj?o et al. 2000,Chemiluminescence determination of thioridazine hydrochloride by flow-injection analysis,"Hydrogen peroxide, potassium permanganate, potassium dichromate, potassium hexacyanoferrate(III), cerium(IV) sulphate and sodium peroxidisulphate have been tested as potential reagents for chemiluminescence generation from the oxidation of phenothiazine derivatives. Only with potassium permanganate in acidic medium were satisfying results achieved. A total of 13 different phenothiazine derivatives produce luminescence of different intensities on oxidation. Thioridazine hydrochloride was chosen to develop a rapid and simple method for its determination in pharmaceutical formulations. The limit of detection is 1.2 x 10(-6) mol l(-1), and 110 samples per hour can be determined.","Chemiluminescence determination of thioridazine hydrochloride by flow-injection analysis Abs: Hydrogen peroxide, potassium permanganate, potassium dichromate, potassium hexacyanoferrate(III), cerium(IV) sulphate and sodium peroxidisulphate have been tested as potential reagents for chemiluminescence generation from the oxidation of phenothiazine derivatives. Only with potassium permanganate in acidic medium were satisfying results achieved. A total of 13 different phenothiazine derivatives produce luminescence of different intensities on oxidation. Thioridazine hydrochloride was chosen to develop a rapid and simple method for its determination in pharmaceutical formulations. The limit of detection is 1.2 x 10(-6) mol l(-1), and 110 samples per hour can be determined."
1234482,Misiuk 2000,Spectrophotometry assay of imipramine and desipramine using ammonium metavanadate and its application to pharmaceutical preparations,Simple and sensitive method for determination of imipramine and desipramine is reported. The procedure is based on the oxidation of the drugs by ammonium metavanadate. Linear calibration graphs were obtained in the concentration range 0.6-40 microg ml(-1) of imipramine and 0.7-35 microg ml(-1) of desipramine with a relative standard deviation (RSD) less than 0.5%. The method was applied to the determination of the drugs in pharmaceutical preparations and compared favourably with independent official methods.,Spectrophotometry assay of imipramine and desipramine using ammonium metavanadate and its application to pharmaceutical preparations Abs: Simple and sensitive method for determination of imipramine and desipramine is reported. The procedure is based on the oxidation of the drugs by ammonium metavanadate. Linear calibration graphs were obtained in the concentration range 0.6-40 microg ml(-1) of imipramine and 0.7-35 microg ml(-1) of desipramine with a relative standard deviation (RSD) less than 0.5%. The method was applied to the determination of the drugs in pharmaceutical preparations and compared favourably with independent official methods.
1234481,Johansen et al. 2000,"Changes in the pattern of sensitization to common contact allergens in denmark between 1985-86 and 1997-98, with a special view to the effect of preventive strategies","The objective of the present study is to describe any changes in the prevalence of sensitization to common contact allergens in patch-tested patients over a 12-year period. Attention is given to possible effects of preventive strategies introduced in Denmark regarding nickel and chromate sensitization during that period, and particular areas of concern are identified. Members of the Danish Contact Dermatitis Group collected patch-test results from consecutive eczema patients as well as information about exposures and demographic variables over a 6-month period in 1985-86. The investigation was repeated in 1997-98 in the same clinics, at the same time of year, using identical methods and patch-test substances, including nickel sulphate 5%, potassium dichromate 0.5% and fragrance mix 8%. Nickel was the most common contact allergen in both study periods, followed by the fragrance mix. In children 0-18 years of age, the frequency of nickel allergy decreased from 24.8% in the first study period to 9.2% in the second study period (P &lt; 0. 0008). Fragrance mix allergy doubled in frequency from 4.1% in 1985-86 to 9.9% in 1997-98, an increase that affected all age groups. Contact allergy to potassium dichromate decreased significantly from 3.0% in the first period to 1.2% in the second period (P = 0. 001). The decrease was seen in both sexes and was most pronounced among those of working age. No other significant changes were found in the frequency of sensitization to common allergens over the 12-year observation period.","Changes in the pattern of sensitization to common contact allergens in denmark between 1985-86 and 1997-98, with a special view to the effect of preventive strategies Abs: The objective of the present study is to describe any changes in the prevalence of sensitization to common contact allergens in patch-tested patients over a 12-year period. Attention is given to possible effects of preventive strategies introduced in Denmark regarding nickel and chromate sensitization during that period, and particular areas of concern are identified. Members of the Danish Contact Dermatitis Group collected patch-test results from consecutive eczema patients as well as information about exposures and demographic variables over a 6-month period in 1985-86. The investigation was repeated in 1997-98 in the same clinics, at the same time of year, using identical methods and patch-test substances, including nickel sulphate 5%, potassium dichromate 0.5% and fragrance mix 8%. Nickel was the most common contact allergen in both study periods, followed by the fragrance mix. In children 0-18 years of age, the frequency of nickel allergy decreased from 24.8% in the first study period to 9.2% in the second study period (P &lt; 0. 0008). Fragrance mix allergy doubled in frequency from 4.1% in 1985-86 to 9.9% in 1997-98, an increase that affected all age groups. Contact allergy to potassium dichromate decreased significantly from 3.0% in the first period to 1.2% in the second period (P = 0. 001). The decrease was seen in both sexes and was most pronounced among those of working age. No other significant changes were found in the frequency of sensitization to common allergens over the 12-year observation period."
1234479,Eberhard et al. 2000,Attempts to establish experimental Cyclospora cayetanensis infection in laboratory animals,"Attempts were made to develop an animal model for Cyclospora cayetanensis to identify a practical laboratory host for studying human cyclosporiasis. Oocysts collected from stool of infected humans in the United States, Haiti, Guatemala, Peru, and Nepal were held in potassium dichromate solution to allow development of sporozoites. The following animal types were inoculated: 9 strains of mice, including adult and neonatal immunocompetent and immune-deficient inbred and outbred strains, rats, sandrats, chickens, ducks, rabbits, jirds, hamsters, ferrets, pigs, dogs, owl monkeys, rhesus monkeys, and cynomolgus monkeys. Most animals were inoculated by gavage, although some of the primates were fed oocysts on food items. The animals were examined for signs of infection, particularly diarrhea, and stool samples were examined for 4-6 wk after inoculation. None of the animals developed patent infections or signs of infection. We conclude that none of the animals tested is susceptible to infection with C. cayetanensis.","Attempts to establish experimental Cyclospora cayetanensis infection in laboratory animals Abs: Attempts were made to develop an animal model for Cyclospora cayetanensis to identify a practical laboratory host for studying human cyclosporiasis. Oocysts collected from stool of infected humans in the United States, Haiti, Guatemala, Peru, and Nepal were held in potassium dichromate solution to allow development of sporozoites. The following animal types were inoculated: 9 strains of mice, including adult and neonatal immunocompetent and immune-deficient inbred and outbred strains, rats, sandrats, chickens, ducks, rabbits, jirds, hamsters, ferrets, pigs, dogs, owl monkeys, rhesus monkeys, and cynomolgus monkeys. Most animals were inoculated by gavage, although some of the primates were fed oocysts on food items. The animals were examined for signs of infection, particularly diarrhea, and stool samples were examined for 4-6 wk after inoculation. None of the animals developed patent infections or signs of infection. We conclude that none of the animals tested is susceptible to infection with C. cayetanensis."
1234478,Stift et al. 2000,Successful treatment of a patient suffering from severe acute potassium dichromate poisoning with liver transplantation,"<strong>BACKGROUND: </strong>Oral ingestion of potassium dichromate produces a complex spectrum of complications. It has an extremely poor prognosis and usually leads to rapid death.<br /><br /><strong>METHODS: </strong>We report the case of a 16-year-old male patient who was admitted to hospital after oral ingestion of potassium dichromate with suicidal intention.<br /><br /><strong>RESULTS: </strong>The patient's condition deteriorated, and he became comatose within 5 days in spite of immediate attempts at detoxification. Because of irreversible liver failure, which occurred within 2 days after admission, and because of cerebral edema, the decision to perform a liver transplantation was made. On day 6 after admission, a compatible donor liver was transplanted. The course of liver transplantation and the patient's subsequent recovery were uneventful.<br /><br /><strong>CONCLUSION: </strong>The rationale for the delayed transplantation was to avoid damage of the new organ because of high serum chromium levels. Despite severe organ damage, the chromium content of the liver was increased. To the authors' knowledge, this is the first case report of acute toxic liver failure, caused by potassium dichromate poisoning, treated successfully by means of liver transplantation.","Successful treatment of a patient suffering from severe acute potassium dichromate poisoning with liver transplantation Abs: <strong>BACKGROUND: </strong>Oral ingestion of potassium dichromate produces a complex spectrum of complications. It has an extremely poor prognosis and usually leads to rapid death.<br /><br /><strong>METHODS: </strong>We report the case of a 16-year-old male patient who was admitted to hospital after oral ingestion of potassium dichromate with suicidal intention.<br /><br /><strong>RESULTS: </strong>The patient's condition deteriorated, and he became comatose within 5 days in spite of immediate attempts at detoxification. Because of irreversible liver failure, which occurred within 2 days after admission, and because of cerebral edema, the decision to perform a liver transplantation was made. On day 6 after admission, a compatible donor liver was transplanted. The course of liver transplantation and the patient's subsequent recovery were uneventful.<br /><br /><strong>CONCLUSION: </strong>The rationale for the delayed transplantation was to avoid damage of the new organ because of high serum chromium levels. Despite severe organ damage, the chromium content of the liver was increased. To the authors' knowledge, this is the first case report of acute toxic liver failure, caused by potassium dichromate poisoning, treated successfully by means of liver transplantation."
1234477,Ananth et al. 2000,Stabilization of chromium(V) species in bovine serum albumin adduct,A detailed investigation of molecular interactions of the protein bovine serum albumin (BSA) with potassium dichromate has been made. Compelling evidence for the formation of a relatively stable Cr(V) species which decays only slowly to afford Cr(III) products has been obtained. The resulting final chromium(III) product mediates in cross-linking of BSA. The implications of the formation of a relatively stable chromium(V) as well as chromium(III)-mediated cross-links in the marker protein are discussed in the context of the metal ion-induced biotoxicity.,Stabilization of chromium(V) species in bovine serum albumin adduct Abs: A detailed investigation of molecular interactions of the protein bovine serum albumin (BSA) with potassium dichromate has been made. Compelling evidence for the formation of a relatively stable Cr(V) species which decays only slowly to afford Cr(III) products has been obtained. The resulting final chromium(III) product mediates in cross-linking of BSA. The implications of the formation of a relatively stable chromium(V) as well as chromium(III)-mediated cross-links in the marker protein are discussed in the context of the metal ion-induced biotoxicity.
1234475,Liliom et al. 2000,Organization-dependent effects of toxic bivalent ions microtubule assembly and glycolysis,"The effects of bivalent ions on tubulin dynamics and the upper phase of glycolysis were investigated at different organization levels in vitro. Cu2+, Cd2+, Hg2+ and CrO4(2-) inhibit the tubulin polymerization at an IC50 of 14-24 microM with high cooperativity and also induce microtubule disassembly. The apparent binding constants of the ions to tubulin, estimated by fluorescence quenching, vary between 6 and 28 microM. BIAcore measurements for tubulin-tubulin interaction suggest that the presence of Cu2+ affects neither koff nor kon, but the amount of the bound tubulin. While the inhibitory effect of Cu2+ on tubulin polymerization is partially abolished by cross-linking of microtubules with substoichiometric amounts of phosphofructokinase or decoration of tubules with cytosolic proteins, in the presence of kinase but not with cytosolic proteins the tubules are resistant to CrO4(2-). No inhibitory effect of Cu2+ or CrO4(2-) on microtubule assembly was detected in the MAP-containing cytosolic fraction. Electron microscopy revealed that tubules assembled in the presence of Cu2+ or CrO4(2-) ions contain aggregates of thread-like oligomers that are less conspicuous in the presence of cytosolic proteins. Cu2+, Cd2+, and Hg2+ inhibit the glycolytic flux in the cytosolic fraction characterized at equilibrium by an IC50 of 10-14 microM with high cooperativity. Tubulin diminishes the inhibitory effect of the cations. These data indicate that the responses elicited by the bivalent ions are highly dependent on the supramolecular organization of the systems.","Organization-dependent effects of toxic bivalent ions microtubule assembly and glycolysis Abs: The effects of bivalent ions on tubulin dynamics and the upper phase of glycolysis were investigated at different organization levels in vitro. Cu2+, Cd2+, Hg2+ and CrO4(2-) inhibit the tubulin polymerization at an IC50 of 14-24 microM with high cooperativity and also induce microtubule disassembly. The apparent binding constants of the ions to tubulin, estimated by fluorescence quenching, vary between 6 and 28 microM. BIAcore measurements for tubulin-tubulin interaction suggest that the presence of Cu2+ affects neither koff nor kon, but the amount of the bound tubulin. While the inhibitory effect of Cu2+ on tubulin polymerization is partially abolished by cross-linking of microtubules with substoichiometric amounts of phosphofructokinase or decoration of tubules with cytosolic proteins, in the presence of kinase but not with cytosolic proteins the tubules are resistant to CrO4(2-). No inhibitory effect of Cu2+ or CrO4(2-) on microtubule assembly was detected in the MAP-containing cytosolic fraction. Electron microscopy revealed that tubules assembled in the presence of Cu2+ or CrO4(2-) ions contain aggregates of thread-like oligomers that are less conspicuous in the presence of cytosolic proteins. Cu2+, Cd2+, and Hg2+ inhibit the glycolytic flux in the cytosolic fraction characterized at equilibrium by an IC50 of 10-14 microM with high cooperativity. Tubulin diminishes the inhibitory effect of the cations. These data indicate that the responses elicited by the bivalent ions are highly dependent on the supramolecular organization of the systems."
1234474,Chuang et al. 2000,"Activation of JNK, p38 and ERK mitogen-activated protein kinases by chromium(VI) is mediated through oxidative stress but does not affect cytotoxicity","In this study we have explored the involvement of oxidative stress in Cr(VI)-induced JNK, p38 and ERK signaling pathways and their effects on Cr(VI) cytotoxicity in human non-small cell lung carcinoma CL3 cells. Exposure to K(2)Cr(2)O(7) markedly activated JNK and p38 and moderately activated ERK in a dose- (10-80 microM) and time-dependent (1-12 h) manner. The activated p38 decreased markedly and rapidly and the activated JNK decreased gradually when Cr(VI) was removed from the medium. Post-incubation of Cr(VI)-treated cells with H(2)O(2) increased the activities of JNK and p38, but not ERK. Co-administering Cr(VI) with 3-amino-1,2, 4-triazole (3AT), a catalase inhibitor, enhanced p38 activation, but did not influence JNK and ERK activation by Cr(VI). Conversely, co-administering Cr(VI) with mannitol, a hydroxyl radical scavenger and a Cr(V) chelator, reduced p38 activation and increased JNK and ERK activation by Cr(VI). These results indicate that p38 activation by Cr(VI) is positively correlated with oxidative stress, while JNK activity can be enhanced by either a quencher (mannitol) or activator (H(2)O(2)) of redox reactions in Cr(VI)-exposed CL3 cells. However, both 3AT and mannitol reduced the cytotoxicity of Cr(VI), but H(2)O(2) did not. The JNK activated by Cr(VI) was decreased (approximately 50%) by expression of a kinase-defective form of MKK7 (MKK7A) but not that of MKK4 (MKK4KR), suggesting that activation of JNK by Cr(VI) is mediated through MKK7. SB202190, a specific inhibitor of p38, markedly decreased JNK but did not change ERK activation by Cr(VI). PD98059, a specific inhibitor of ERK kinases MKK1/2, blocked ERK and p38 but did not alter JNK activation by Cr(VI). Neither the specific kinase inhibitors nor expression of MKK7A altered Cr(VI)-induced cytotoxicity. Together, these results suggest that activation of the JNK, p38 and ERK pathways by Cr(VI) is mediated through diverse redox mechanisms, yet their activation does not correlate with Cr(VI) cytotoxicity.","Activation of JNK, p38 and ERK mitogen-activated protein kinases by chromium(VI) is mediated through oxidative stress but does not affect cytotoxicity Abs: In this study we have explored the involvement of oxidative stress in Cr(VI)-induced JNK, p38 and ERK signaling pathways and their effects on Cr(VI) cytotoxicity in human non-small cell lung carcinoma CL3 cells. Exposure to K(2)Cr(2)O(7) markedly activated JNK and p38 and moderately activated ERK in a dose- (10-80 microM) and time-dependent (1-12 h) manner. The activated p38 decreased markedly and rapidly and the activated JNK decreased gradually when Cr(VI) was removed from the medium. Post-incubation of Cr(VI)-treated cells with H(2)O(2) increased the activities of JNK and p38, but not ERK. Co-administering Cr(VI) with 3-amino-1,2, 4-triazole (3AT), a catalase inhibitor, enhanced p38 activation, but did not influence JNK and ERK activation by Cr(VI). Conversely, co-administering Cr(VI) with mannitol, a hydroxyl radical scavenger and a Cr(V) chelator, reduced p38 activation and increased JNK and ERK activation by Cr(VI). These results indicate that p38 activation by Cr(VI) is positively correlated with oxidative stress, while JNK activity can be enhanced by either a quencher (mannitol) or activator (H(2)O(2)) of redox reactions in Cr(VI)-exposed CL3 cells. However, both 3AT and mannitol reduced the cytotoxicity of Cr(VI), but H(2)O(2) did not. The JNK activated by Cr(VI) was decreased (approximately 50%) by expression of a kinase-defective form of MKK7 (MKK7A) but not that of MKK4 (MKK4KR), suggesting that activation of JNK by Cr(VI) is mediated through MKK7. SB202190, a specific inhibitor of p38, markedly decreased JNK but did not change ERK activation by Cr(VI). PD98059, a specific inhibitor of ERK kinases MKK1/2, blocked ERK and p38 but did not alter JNK activation by Cr(VI). Neither the specific kinase inhibitors nor expression of MKK7A altered Cr(VI)-induced cytotoxicity. Together, these results suggest that activation of the JNK, p38 and ERK pathways by Cr(VI) is mediated through diverse redox mechanisms, yet their activation does not correlate with Cr(VI) cytotoxicity."
1234473,Singhal and  Reddy 2000,Common contact sensitizers in Delhi,"Seventy-five patients of both sexes with clinically suspected contact dermatitis were patch tested with the Indian Standard Series and indigenous antigens. The results were compared with the data from other centers. Most of these patients were young adults between 20 and 39 yrs old with the mean age of 36.63 +/- 5.6 yrs. Their occupational profiles included household workers (17.33%), masons (10.66%), farmers (6.66%), factory workers (4%), medical personnel (4%), lab workers (2.66%), and miscellaneous (17.33%). Itching and burning were two of the most common complaints, and chronic dermatitis was the predominant morphologic pattern of the lesions observed. Frequent sites involved included the hands (40.83%), airborne type (22.44%), hands and feet (12.24%), feet (12.24%), face (10.2%), and neck (2.04%). Patch test analysis of these patients revealed that, out of 75 subjects tested, 49 (65.3%) reacted to one or more allergens. Parthenium (20%) is the most common contact sensitizer followed by potassium dichromate (16%), xanthium (13.33%), nickel sulphate (12%), chrysanthemum (8%), mercaptobenzothiazole, and garlic (6.66% each). These findings are in broad conformity with those in other reports. We concluded that the Indian Standard Series of antigens with the addition of a few more (such as garlic, onion and chlorheximide of local relevance) is suitable for detecting the allergens responsible for the contact dermatitis prevailing in this region.","Common contact sensitizers in Delhi Abs: Seventy-five patients of both sexes with clinically suspected contact dermatitis were patch tested with the Indian Standard Series and indigenous antigens. The results were compared with the data from other centers. Most of these patients were young adults between 20 and 39 yrs old with the mean age of 36.63 +/- 5.6 yrs. Their occupational profiles included household workers (17.33%), masons (10.66%), farmers (6.66%), factory workers (4%), medical personnel (4%), lab workers (2.66%), and miscellaneous (17.33%). Itching and burning were two of the most common complaints, and chronic dermatitis was the predominant morphologic pattern of the lesions observed. Frequent sites involved included the hands (40.83%), airborne type (22.44%), hands and feet (12.24%), feet (12.24%), face (10.2%), and neck (2.04%). Patch test analysis of these patients revealed that, out of 75 subjects tested, 49 (65.3%) reacted to one or more allergens. Parthenium (20%) is the most common contact sensitizer followed by potassium dichromate (16%), xanthium (13.33%), nickel sulphate (12%), chrysanthemum (8%), mercaptobenzothiazole, and garlic (6.66% each). These findings are in broad conformity with those in other reports. We concluded that the Indian Standard Series of antigens with the addition of a few more (such as garlic, onion and chlorheximide of local relevance) is suitable for detecting the allergens responsible for the contact dermatitis prevailing in this region."
1234472,Törökné et al. 2000,Utilization of microbiotests to assess the contamination of water-bases,"In the present study 4 hazardous wastes originated from 4 different typical industrial activities (leachates of waste oil, waste stockpiles of aluminium factory, sewage of leather industry and of the chemical industry) were examined with several Toxkit microbiotests: the Algaltoxkit, the Protoxkit, the Daphtoxkit and the Thamnotoxkit. The data obtained with the microbiotests were compared to those obtained with the standard conventional acute toxicity tests. The goal of the study was to try out the reproducibility of the tests on the same samples, prepared in the same laboratory and provided to all the participants of the interlaboratory exercise. The first reproducibility evaluation of the tests was made with the reference toxicant potassium dichromate (K2Cr2O7). The outcome was that the lowest coefficients of variation were found at the Thamnotoxkit and highest with Algaltoxkit. The same findings were observed with the industrial waste samples. Different responses were obtained depending on the preparation and the character of the waste. For example, whereas a strong (and highest) toxic effect was found with the Thamnotoxkit, the algal cells in the Algaltoxkit test grew better than in the controls, when exposed to the same waste sample. The sensitivity of the Protoxkit ciliates was the lowest for all the wastes examined. In conclusion of this study, the experience gained and data obtained indicate that the Toxkit microbiotests are suited for routine monitoring after modification of some technical aspects.","Utilization of microbiotests to assess the contamination of water-bases Abs: In the present study 4 hazardous wastes originated from 4 different typical industrial activities (leachates of waste oil, waste stockpiles of aluminium factory, sewage of leather industry and of the chemical industry) were examined with several Toxkit microbiotests: the Algaltoxkit, the Protoxkit, the Daphtoxkit and the Thamnotoxkit. The data obtained with the microbiotests were compared to those obtained with the standard conventional acute toxicity tests. The goal of the study was to try out the reproducibility of the tests on the same samples, prepared in the same laboratory and provided to all the participants of the interlaboratory exercise. The first reproducibility evaluation of the tests was made with the reference toxicant potassium dichromate (K2Cr2O7). The outcome was that the lowest coefficients of variation were found at the Thamnotoxkit and highest with Algaltoxkit. The same findings were observed with the industrial waste samples. Different responses were obtained depending on the preparation and the character of the waste. For example, whereas a strong (and highest) toxic effect was found with the Thamnotoxkit, the algal cells in the Algaltoxkit test grew better than in the controls, when exposed to the same waste sample. The sensitivity of the Protoxkit ciliates was the lowest for all the wastes examined. In conclusion of this study, the experience gained and data obtained indicate that the Toxkit microbiotests are suited for routine monitoring after modification of some technical aspects."
1234470,Pritchard et al. 2000,Chromium (VI) increases endothelial cell expression of ICAM-1 and decreases nitric oxide activity,"Occupational, airborne pollutants, such as heavy metals, are recognized for inducing injury and cytotoxicity. Chromium(VI) is a redox cycling heavy metal that has been strongly implicated in the initiation of cancer. Its proinflammatory effects, however, have not been systematically examined. In our study, we found that potassium dichromate [Cr(VI)] treatment of human umbilical vein endothelial cells (HUVEC) increased intracellular adhesion molecule (ICAM) expression at the message level. ICAM message levels remained elevated for 12-24 hours after exposure and increased with time and concentration. Cr(VI) increased the release of superoxide anion without affecting the ability of endothelial cultures to produce nitric oxide. However, Cr(VI) decreased cGMP in HUVEC, suggesting that the nitric oxide produced was scavenged intracellularly. Cr(VI) also increased nitrotyrosine in HUVEC cultures. These data are consistent with the idea that exposure to Cr(VI) increases the production of superoxide anion, which scavenges nitric oxide to increase the formation of peroxynitrite. The loss in nitric oxide activity and increased formation of peroxynitrite likely enhance endothelial cell expression of ICAM-1. Cr(VI)-induced increases in the adhesive properties of the endothelium may play a critical role in the initiation and progression of tissue injury through increased recruitment of proinflammatory white blood cells.","Chromium (VI) increases endothelial cell expression of ICAM-1 and decreases nitric oxide activity Abs: Occupational, airborne pollutants, such as heavy metals, are recognized for inducing injury and cytotoxicity. Chromium(VI) is a redox cycling heavy metal that has been strongly implicated in the initiation of cancer. Its proinflammatory effects, however, have not been systematically examined. In our study, we found that potassium dichromate [Cr(VI)] treatment of human umbilical vein endothelial cells (HUVEC) increased intracellular adhesion molecule (ICAM) expression at the message level. ICAM message levels remained elevated for 12-24 hours after exposure and increased with time and concentration. Cr(VI) increased the release of superoxide anion without affecting the ability of endothelial cultures to produce nitric oxide. However, Cr(VI) decreased cGMP in HUVEC, suggesting that the nitric oxide produced was scavenged intracellularly. Cr(VI) also increased nitrotyrosine in HUVEC cultures. These data are consistent with the idea that exposure to Cr(VI) increases the production of superoxide anion, which scavenges nitric oxide to increase the formation of peroxynitrite. The loss in nitric oxide activity and increased formation of peroxynitrite likely enhance endothelial cell expression of ICAM-1. Cr(VI)-induced increases in the adhesive properties of the endothelium may play a critical role in the initiation and progression of tissue injury through increased recruitment of proinflammatory white blood cells."
1234469,Travacio et al. 2000,Chromium(VI) induces oxidative stress in the mouse brain,"Potassium dichromate was given to female Swiss mice (25 mg/kg per day) orally in water for 1-3 days. Brain homogenates were prepared to evaluate the occurrence of oxidative stress in this organ through the measurement of the antioxidant defense levels, and the extent of lipid peroxidation. In addition, mitochondrial fractions were isolated from brain homogenates to determine the production of reactive oxygen species in this subcellular fraction. The administration of potassium dichromate for 3 days caused increases of 72 and 74% in superoxide dismutase and catalase activities, respectively, in the homogenates. The treatment with this metal for 3 days increased brain homogenate chemiluminescence and thiobarbituric acid-reactive substances by 34 and 29%, respectively. The brain contents of the non-enzymatic antioxidants alpha-tocopherol and sulfhydryl groups decreased by 35 and 32%, respectively. Ascorbic acid levels were not modified by the administration of potassium dichromate. Finally, there was a significant increment in the mitochondrial production of oxidants in the brain of treated mice as compared with controls. These results suggest that chromium(VI) produces an increased formation of reactive oxygen species and brain lipid peroxidation. The increase in the antioxidant enzyme activities reflects an adaptive response against oxidative stress, while the reduction in the levels of non-enzymatic antioxidants might be due to their reaction with reactive oxygen species generated during the metabolism of chromium(VI).","Chromium(VI) induces oxidative stress in the mouse brain Abs: Potassium dichromate was given to female Swiss mice (25 mg/kg per day) orally in water for 1-3 days. Brain homogenates were prepared to evaluate the occurrence of oxidative stress in this organ through the measurement of the antioxidant defense levels, and the extent of lipid peroxidation. In addition, mitochondrial fractions were isolated from brain homogenates to determine the production of reactive oxygen species in this subcellular fraction. The administration of potassium dichromate for 3 days caused increases of 72 and 74% in superoxide dismutase and catalase activities, respectively, in the homogenates. The treatment with this metal for 3 days increased brain homogenate chemiluminescence and thiobarbituric acid-reactive substances by 34 and 29%, respectively. The brain contents of the non-enzymatic antioxidants alpha-tocopherol and sulfhydryl groups decreased by 35 and 32%, respectively. Ascorbic acid levels were not modified by the administration of potassium dichromate. Finally, there was a significant increment in the mitochondrial production of oxidants in the brain of treated mice as compared with controls. These results suggest that chromium(VI) produces an increased formation of reactive oxygen species and brain lipid peroxidation. The increase in the antioxidant enzyme activities reflects an adaptive response against oxidative stress, while the reduction in the levels of non-enzymatic antioxidants might be due to their reaction with reactive oxygen species generated during the metabolism of chromium(VI)."
1234468,Pereira and  Cunha 2000,Allergic contact dermatitis from chromate and 4-tert-butylphenol-formaldehyde resin in a father and daughter,,Allergic contact dermatitis from chromate and 4-tert-butylphenol-formaldehyde resin in a father and daughter Abs: 
1234467,Ortiz et al. 2000,Microcomputed tomography of kidneys following chronic bile duct ligation,"<strong>BACKGROUND: </strong>In hepatic cirrhosis, renal sodium and water retention can occur prior to decreases in renal blood flow (RBF). This may be explained in part by redistribution of the intrarenal microcirculation toward the juxtamedullary nephrons. To appreciate this three-dimensional spatial redistribution better, we examined the intrarenal microcirculatory changes using microcomputed tomography (micro-CT) in rats subjected to chronic bile duct ligation (CBDL).<br /><br /><strong>METHODS: </strong>Six kidneys from control rats and eight kidneys from rats that had undergone CBDL for 21 days were perfusion fixed in situ at physiological pressure, perfused with silicon-based Microfil containing lead chromate, embedded in plastic, and scanned by micro-CT. The microvasculature in the reconstructed three-dimensional renal images was studied using computerized image-analysis techniques. To determine the physiological condition of the rats, parallel experiments were conducted on six control and six CBDL rats to measure mean arterial pressure (MAP), RBF, glomerular filtration rate (GFR), urine flow (UF) rate, and sodium excretion by conventional methods.<br /><br /><strong>RESULTS: </strong>The percentage of vasculature in the renal cortex from CBDL rats was significantly decreased (10.8 +/- 0.4% vs. 16.8 +/- 2.7% control values). However, the vascular volume fractions of the medullary tissues were not significantly altered. There were no significant differences in the number of glomeruli between groups (36,430 +/- 1908 CBDLs, 36,609 +/- 3167 controls). The CBDL rats had a similar GFR than the controls but a reduced MAP, RBF, UF, and sodium excretion.<br /><br /><strong>CONCLUSIONS: </strong>The results indicate that after CBDL, there is a selective decrease in cortical vascular filling, which may contribute to the salt and water retention that accompanies cirrhosis.","Microcomputed tomography of kidneys following chronic bile duct ligation Abs: <strong>BACKGROUND: </strong>In hepatic cirrhosis, renal sodium and water retention can occur prior to decreases in renal blood flow (RBF). This may be explained in part by redistribution of the intrarenal microcirculation toward the juxtamedullary nephrons. To appreciate this three-dimensional spatial redistribution better, we examined the intrarenal microcirculatory changes using microcomputed tomography (micro-CT) in rats subjected to chronic bile duct ligation (CBDL).<br /><br /><strong>METHODS: </strong>Six kidneys from control rats and eight kidneys from rats that had undergone CBDL for 21 days were perfusion fixed in situ at physiological pressure, perfused with silicon-based Microfil containing lead chromate, embedded in plastic, and scanned by micro-CT. The microvasculature in the reconstructed three-dimensional renal images was studied using computerized image-analysis techniques. To determine the physiological condition of the rats, parallel experiments were conducted on six control and six CBDL rats to measure mean arterial pressure (MAP), RBF, glomerular filtration rate (GFR), urine flow (UF) rate, and sodium excretion by conventional methods.<br /><br /><strong>RESULTS: </strong>The percentage of vasculature in the renal cortex from CBDL rats was significantly decreased (10.8 +/- 0.4% vs. 16.8 +/- 2.7% control values). However, the vascular volume fractions of the medullary tissues were not significantly altered. There were no significant differences in the number of glomeruli between groups (36,430 +/- 1908 CBDLs, 36,609 +/- 3167 controls). The CBDL rats had a similar GFR than the controls but a reduced MAP, RBF, UF, and sodium excretion.<br /><br /><strong>CONCLUSIONS: </strong>The results indicate that after CBDL, there is a selective decrease in cortical vascular filling, which may contribute to the salt and water retention that accompanies cirrhosis."
1234465,Merk et al. 2000,Analysis of chromate-induced DNA-protein crosslinks with the comet assay,"Modifications of the comet assay have been introduced to measure crosslinks by determining the reduction of induced DNA migration. Our previous results indicated that the modified protocol of the alkaline comet assay is a sensitive tool for the detection of formaldehyde-induced DNA-protein crosslinks. But results for mitomycin C and cisplatin suggested that the modified protocol is not well suited for the evaluation of DNA-DNA crosslinkers. We now used the comet assay to investigate in V79 cells the effect of potassium chromate (K(2)CrO(4)), another DNA-protein crosslinker, to see whether the results obtained for formaldehyde can be generalized. However, chromate did not reduce spontaneous or radiation-induced DNA migration in the alkaline (pH 13) comet assay but led to a small but significant induction of DNA migration. A crosslinking effect of chromate could also not be detected with the alkaline comet assay after postincubation of cells in normal medium after chromate treatment to enable repair of other (migration-inducing) lesions that might mask the crosslinking effect. Exposure of slides to proteinase K further increased DNA migration of chromate-treated cells, thus indicating the presence of DNA-protein crosslinks. In contrast to the alkaline comet assay, a &quot;neutral&quot; version at pH 9 was suited to demonstrate reduced induction of DNA migration after gamma-irradiation of chromate-treated cells. The crosslinking effect was seen immediately at the end of the chromate treatment as well as after a 3h postincubation period. Using the &quot;neutral&quot; protocol in combination with proteinase K, we were able to demonstrate the presence of DNA-protein crosslinks as the probable cause for the migration-reducing effect. Further investigations will have to show whether this protocol can be recommended as a universal approach for the detection of DNA-protein crosslinks and also of DNA-DNA crosslinks with the comet assay.","Analysis of chromate-induced DNA-protein crosslinks with the comet assay Abs: Modifications of the comet assay have been introduced to measure crosslinks by determining the reduction of induced DNA migration. Our previous results indicated that the modified protocol of the alkaline comet assay is a sensitive tool for the detection of formaldehyde-induced DNA-protein crosslinks. But results for mitomycin C and cisplatin suggested that the modified protocol is not well suited for the evaluation of DNA-DNA crosslinkers. We now used the comet assay to investigate in V79 cells the effect of potassium chromate (K(2)CrO(4)), another DNA-protein crosslinker, to see whether the results obtained for formaldehyde can be generalized. However, chromate did not reduce spontaneous or radiation-induced DNA migration in the alkaline (pH 13) comet assay but led to a small but significant induction of DNA migration. A crosslinking effect of chromate could also not be detected with the alkaline comet assay after postincubation of cells in normal medium after chromate treatment to enable repair of other (migration-inducing) lesions that might mask the crosslinking effect. Exposure of slides to proteinase K further increased DNA migration of chromate-treated cells, thus indicating the presence of DNA-protein crosslinks. In contrast to the alkaline comet assay, a &quot;neutral&quot; version at pH 9 was suited to demonstrate reduced induction of DNA migration after gamma-irradiation of chromate-treated cells. The crosslinking effect was seen immediately at the end of the chromate treatment as well as after a 3h postincubation period. Using the &quot;neutral&quot; protocol in combination with proteinase K, we were able to demonstrate the presence of DNA-protein crosslinks as the probable cause for the migration-reducing effect. Further investigations will have to show whether this protocol can be recommended as a universal approach for the detection of DNA-protein crosslinks and also of DNA-DNA crosslinks with the comet assay."
1234464,Rudolf et al. 2000,The dynamics of the hexavalent chromium induced apoptotic patterns in vitro,"Although hexavalent chromium has been shown to induce apoptosis in cells cultivated in vitro, there appear to be no studies focusing on the dynamics of this process. To find out about dynamic patterns of hexavalent chromium-induced apoptosis, we treated Hep2 cells with 150 micrograms/ml potassium chromate and recorded their behavior as well as appearance of some crucial organelles using different morphological and biochemical methods. We found that Hep2 cells showed the earliest observable changes at 6 hours after the treatment (blebbing, chromatin shrinkage), with the entire apoptotic process lasting up to 24 hours. While all the observed cell features clearly prove apoptosis induced by hexavalent chromium, a typical apoptotic hallmark, DNA ladder, seems not to occur in this type of cells. On the other hand, in HL60 cells, used as a control, this ladder was observable.","The dynamics of the hexavalent chromium induced apoptotic patterns in vitro Abs: Although hexavalent chromium has been shown to induce apoptosis in cells cultivated in vitro, there appear to be no studies focusing on the dynamics of this process. To find out about dynamic patterns of hexavalent chromium-induced apoptosis, we treated Hep2 cells with 150 micrograms/ml potassium chromate and recorded their behavior as well as appearance of some crucial organelles using different morphological and biochemical methods. We found that Hep2 cells showed the earliest observable changes at 6 hours after the treatment (blebbing, chromatin shrinkage), with the entire apoptotic process lasting up to 24 hours. While all the observed cell features clearly prove apoptosis induced by hexavalent chromium, a typical apoptotic hallmark, DNA ladder, seems not to occur in this type of cells. On the other hand, in HL60 cells, used as a control, this ladder was observable."
1234463,Walter et al. 2000,Does potassium dichromate induce apoptosis in lymphocytes?,"The aim of this work was to investigate the possibility of apoptosis in the human peripheral blood lymphocytes after treatment with potassium dichromate (K2Cr2O7), a potential occupational carcinogenic and mutagenic agent. Lymphocytes were stimulated by phytohemagglutinin, cultured for 72 h and incubated with either 0.2 mM or 0.4 mM K2Cr2O7 for the last 24 h or 48 h of culture. The condensation and margination of chromatin with emerging 'half-moon' structure, characteristic of apoptosis were observed. Phosphatidylserine displaced from the inner to outer side of the cellular membrane in 54% of cells after a 48-h incubation with 0.4 mM K2Cr2O7 (annexin-V+/PI-); 39% of these cells were of late apoptotic--secondary necrotic form (annexin-V+/PI+). Following the agarose gel electrophoresis of DNA, a 'ladder pattern' typical of apoptosis, was found. The results of the present study demonstrate that K2Cr2O7 can induce in the human peripheral blood lymphocytes changes similar to apoptotic ones.","Does potassium dichromate induce apoptosis in lymphocytes? Abs: The aim of this work was to investigate the possibility of apoptosis in the human peripheral blood lymphocytes after treatment with potassium dichromate (K2Cr2O7), a potential occupational carcinogenic and mutagenic agent. Lymphocytes were stimulated by phytohemagglutinin, cultured for 72 h and incubated with either 0.2 mM or 0.4 mM K2Cr2O7 for the last 24 h or 48 h of culture. The condensation and margination of chromatin with emerging 'half-moon' structure, characteristic of apoptosis were observed. Phosphatidylserine displaced from the inner to outer side of the cellular membrane in 54% of cells after a 48-h incubation with 0.4 mM K2Cr2O7 (annexin-V+/PI-); 39% of these cells were of late apoptotic--secondary necrotic form (annexin-V+/PI+). Following the agarose gel electrophoresis of DNA, a 'ladder pattern' typical of apoptosis, was found. The results of the present study demonstrate that K2Cr2O7 can induce in the human peripheral blood lymphocytes changes similar to apoptotic ones."
1234462,Poon et al. 2001,The effect of flow-through leaching on the diffusivity of heavy metals in stabilized/solidified wastes,"The flow-through leaching test is a test method employed to study the leaching behavior of monolithic stabilized/solidified (S/S) hazardous wastes under the condition that the leachate flows through the sample. This method simulates the leaching process of the S/S hazardous waste disposed under a particular landfill condition when the S/S waste is more permeable than its surrounding materials or when the deterioration of the solidified waste form has reached a state that ground water can flow-through the waste via the porosity system of the S/S waste matrix. This paper describes a study on the long-term performance of the cement-based S/S heavy metal wastes using a flow-through leaching test method. Two series of leaching tests with different synthetic heavy metal waste samples were carried out. The S/S samples were made from five types of heavy metals with two kinds of binders. The metals were Pb(2+), Zn(2+), Cu(2+), Ni(2+) (positive ions as nitrates), and Cr(6+) (a negative ion as potassium dichromate), and the binders were type I ordinary portland cement (OPC) and pulverised fuel ash (PFA). The model developed by Godbee and Joy for simulating the leaching behavior was modified to estimate the diffusivity parameter in this study. The results obtained indicate that since the matrix of the solidified waste in a flow-through leaching tests is always being degraded, the values of diffusivities increase continuously during the leaching period. The diffusivity variation range was from 10(-13) to 10(-3)cm(2)/s, and were normally higher than those obtained from other test methods such as ANS 16.1 test and other dynamic leaching tests.","The effect of flow-through leaching on the diffusivity of heavy metals in stabilized/solidified wastes Abs: The flow-through leaching test is a test method employed to study the leaching behavior of monolithic stabilized/solidified (S/S) hazardous wastes under the condition that the leachate flows through the sample. This method simulates the leaching process of the S/S hazardous waste disposed under a particular landfill condition when the S/S waste is more permeable than its surrounding materials or when the deterioration of the solidified waste form has reached a state that ground water can flow-through the waste via the porosity system of the S/S waste matrix. This paper describes a study on the long-term performance of the cement-based S/S heavy metal wastes using a flow-through leaching test method. Two series of leaching tests with different synthetic heavy metal waste samples were carried out. The S/S samples were made from five types of heavy metals with two kinds of binders. The metals were Pb(2+), Zn(2+), Cu(2+), Ni(2+) (positive ions as nitrates), and Cr(6+) (a negative ion as potassium dichromate), and the binders were type I ordinary portland cement (OPC) and pulverised fuel ash (PFA). The model developed by Godbee and Joy for simulating the leaching behavior was modified to estimate the diffusivity parameter in this study. The results obtained indicate that since the matrix of the solidified waste in a flow-through leaching tests is always being degraded, the values of diffusivities increase continuously during the leaching period. The diffusivity variation range was from 10(-13) to 10(-3)cm(2)/s, and were normally higher than those obtained from other test methods such as ANS 16.1 test and other dynamic leaching tests."
1234461,Ueno et al. 2001,Detection of dichromate (VI)-induced DNA strand breaks and formation of paramagnetic chromium in multiple mouse organs,"DNA single-strand breaks (and/or alkali-labile sites) induced by Cr(VI) were evaluated with the alkaline single cell gel electrophoresis (SCG) (Comet) assay in five organs (liver, kidney, spleen, lung, and brain) of male mice dosed with K(2)Cr(2)O(7) (20 mg Cr/kg) by a single ip injection in vivo, and the formation of paramagnetic Cr(V) in these organs was investigated by electron spin resonance (ESR) spectrometry. Furthermore, the in vivo effects of deferoxamine (DFO), an iron chelator, and dimethylthiourea (DMTU), a hydroxyl radical scavenger, on the formation of Cr(V) and DNA strand breaks induced by the metal in the liver and kidney were examined. SCG assay detected DNA strand breaks were detected in the liver and kidney at 15 min and showed that they were being repaired at 3 h after Cr(VI) injection. The ESR spectra of paramagnetic Cr(V) were also observed in the liver and kidney for 15 min to 24 h after Cr(VI) injection. In contrast, there were no significant levels of DNA strand breaks and Cr(V) in the spleen, lung, or brain. The pretreatment of mice with DFO reduced the formation of Cr(VI)-induced DNA strand breaks and Cr(V) complexes as well as the total contents of Cr in the liver and kidney at 15 min after the metal injection. In the case of the pretreatment with DMTU, DNA strand breaks induced by Cr(VI) were suppressed in the liver and kidney at 15 min, without any influence on the levels of Cr(V) complexes and total Cr contents in the organs. The in vitro study showed that DFO decreased the levels of Cr(V)-GSH complexes and Cr(V)-mediated hydroxyl radicals, while DMTU reduced only the levels of Cr(V)-mediated hydroxyl radicals without affecting the formation of Cr(V)-GSH complexes. These results demonstrated that the SCG assay may be useful for detecting DNA strand breaks and/or alkali-labile sites caused by Cr(VI) in vivo. The results also indicated that the in vivo formation of hydroxyl radicals during the reduction of Cr(VI) may play an important role in the induction of the DNA strand breaks caused by this metal and implied that the levels of Cr(V) inside the cells may not always be related to the induction of DNA strand breaks.","Detection of dichromate (VI)-induced DNA strand breaks and formation of paramagnetic chromium in multiple mouse organs Abs: DNA single-strand breaks (and/or alkali-labile sites) induced by Cr(VI) were evaluated with the alkaline single cell gel electrophoresis (SCG) (Comet) assay in five organs (liver, kidney, spleen, lung, and brain) of male mice dosed with K(2)Cr(2)O(7) (20 mg Cr/kg) by a single ip injection in vivo, and the formation of paramagnetic Cr(V) in these organs was investigated by electron spin resonance (ESR) spectrometry. Furthermore, the in vivo effects of deferoxamine (DFO), an iron chelator, and dimethylthiourea (DMTU), a hydroxyl radical scavenger, on the formation of Cr(V) and DNA strand breaks induced by the metal in the liver and kidney were examined. SCG assay detected DNA strand breaks were detected in the liver and kidney at 15 min and showed that they were being repaired at 3 h after Cr(VI) injection. The ESR spectra of paramagnetic Cr(V) were also observed in the liver and kidney for 15 min to 24 h after Cr(VI) injection. In contrast, there were no significant levels of DNA strand breaks and Cr(V) in the spleen, lung, or brain. The pretreatment of mice with DFO reduced the formation of Cr(VI)-induced DNA strand breaks and Cr(V) complexes as well as the total contents of Cr in the liver and kidney at 15 min after the metal injection. In the case of the pretreatment with DMTU, DNA strand breaks induced by Cr(VI) were suppressed in the liver and kidney at 15 min, without any influence on the levels of Cr(V) complexes and total Cr contents in the organs. The in vitro study showed that DFO decreased the levels of Cr(V)-GSH complexes and Cr(V)-mediated hydroxyl radicals, while DMTU reduced only the levels of Cr(V)-mediated hydroxyl radicals without affecting the formation of Cr(V)-GSH complexes. These results demonstrated that the SCG assay may be useful for detecting DNA strand breaks and/or alkali-labile sites caused by Cr(VI) in vivo. The results also indicated that the in vivo formation of hydroxyl radicals during the reduction of Cr(VI) may play an important role in the induction of the DNA strand breaks caused by this metal and implied that the levels of Cr(V) inside the cells may not always be related to the induction of DNA strand breaks."
1234460,Rizki et al. 2001,Antigenotoxic properties of selenium: studies in the wing spot test in Drosophila,"The genotoxic activity of three selenium compounds (sodium selenite, sodium selenate, and selenious acid) and the antigenotoxic effects of sodium selenite in combination with the chromium compound potassium dichromate were studied using the wing spot test of Drosophila melanogaster. This assay is based on the principle that the loss of heterozygosity of suitable recessive markers, multiple wing hairs (mwh) and flare-3 (flr[3]), can lead to the formation of mutant clones of larval cells, which are then expressed as spots on the wings of the adult flies. Pretreatment and chronic cotreatment was comparatively used for the antigenotoxicity study. From the results obtained, it was evident that all selenium compounds are unable to increase the frequency of any of the three categories of spots recorded (small, large, and twin spots). Nevertheless, the antigenotoxic effects of sodium selenite were clearly demonstrated, in both cotreatment and pretreatment, by a complete suppression of those clones induced by potassium dichromate. Therefore, the D. melanogaster wing spot test was revealed to be a good assay, not only for evaluating genotoxic activity but also for detecting antigenotoxic effects in vivo.","Antigenotoxic properties of selenium: studies in the wing spot test in Drosophila Abs: The genotoxic activity of three selenium compounds (sodium selenite, sodium selenate, and selenious acid) and the antigenotoxic effects of sodium selenite in combination with the chromium compound potassium dichromate were studied using the wing spot test of Drosophila melanogaster. This assay is based on the principle that the loss of heterozygosity of suitable recessive markers, multiple wing hairs (mwh) and flare-3 (flr[3]), can lead to the formation of mutant clones of larval cells, which are then expressed as spots on the wings of the adult flies. Pretreatment and chronic cotreatment was comparatively used for the antigenotoxicity study. From the results obtained, it was evident that all selenium compounds are unable to increase the frequency of any of the three categories of spots recorded (small, large, and twin spots). Nevertheless, the antigenotoxic effects of sodium selenite were clearly demonstrated, in both cotreatment and pretreatment, by a complete suppression of those clones induced by potassium dichromate. Therefore, the D. melanogaster wing spot test was revealed to be a good assay, not only for evaluating genotoxic activity but also for detecting antigenotoxic effects in vivo."
1234459,de Carvalho and  Schwedt 2000,"Sulfur speciation by capillary zone electrophoresis: conditions for sulfite stabilization and determination in the presence of sulfate, thiosulfate and peroxodisulfate","Capillary zone electrophoresis (CZE) was used for the separation of the sulfur species SO3(2-), SO4(2-), S2O(3-) and S2O8(2-). Using an electrolyte system with 9.5 mmol L(-1) potassium chromate as UV-absorbing probe and 1 mmol L(-1) diethylenetriamine (DETA) as electroosmotic flow modifier, various possibilities for the stabilization of sulfite and electrophoretic separation of the sulfur anions were investigated. By adding 5% propanol as a stabilizer to both the working electrolyte and the sample solution, a good stabilization for sulfite and a separation of the sulfur anions in a short analysis time (4 min) was achieved. The advantages by using propanol instead of other stabilizers often used in analytical techniques are discussed. The electrophoretic separation of the sulfur anions was optimized with respect to the pH of the working electrolyte and concentration of the electroosmotic flow modifier (DETA). The detection limits achieved for SO3(2-), SO4(2-), S2O3(2-) and S2O8(2-) were 0.35, 0.25, 0.78 and 0.80 mg L(-1), respectively.","Sulfur speciation by capillary zone electrophoresis: conditions for sulfite stabilization and determination in the presence of sulfate, thiosulfate and peroxodisulfate Abs: Capillary zone electrophoresis (CZE) was used for the separation of the sulfur species SO3(2-), SO4(2-), S2O(3-) and S2O8(2-). Using an electrolyte system with 9.5 mmol L(-1) potassium chromate as UV-absorbing probe and 1 mmol L(-1) diethylenetriamine (DETA) as electroosmotic flow modifier, various possibilities for the stabilization of sulfite and electrophoretic separation of the sulfur anions were investigated. By adding 5% propanol as a stabilizer to both the working electrolyte and the sample solution, a good stabilization for sulfite and a separation of the sulfur anions in a short analysis time (4 min) was achieved. The advantages by using propanol instead of other stabilizers often used in analytical techniques are discussed. The electrophoretic separation of the sulfur anions was optimized with respect to the pH of the working electrolyte and concentration of the electroosmotic flow modifier (DETA). The detection limits achieved for SO3(2-), SO4(2-), S2O3(2-) and S2O8(2-) were 0.35, 0.25, 0.78 and 0.80 mg L(-1), respectively."
1234458,Pattison et al. 2000,EPR studies of chromium(V) intermediates generated via reduction of chromium(VI) by DOPA and related catecholamines: potential role for oxidized amino acids in chromium-induced cancers,"The reductions of K2Cr2O7 by catecholamines, DOPA, DOPA-beta,beta-d2, N-acetyl-DOPA, alpha-methyl-DOPA, dopamine, adrenaline, noradrenaline, catechol, 1,2-dihydroxybenzoic acid (DHBA), and 4-tert-butylcatechol (TBC), produce a number of Cr(V) electron paramagnetic resonance (EPR) signals. These species are of interest in relation to the potential role of oxidized proteins and amino acids in Cr-induced cancers. With excess organic ligand, all of the substrates yield Cr species with signals at g(iso) approximately 1.972 (Aiso(53Cr) &gt; 23.9 x 10(-4) cm(-1)). These are similar to signals reported previously but have been reassigned as octahedral Cr(V) species with mixed catechol-derived ligands, [CrV(semiquinone)2(catecholate)]+. Experiments with excess K2Cr2O7 show complex behavior with the catecholamines and TBC. Several weak Cr(V) signals are detected after mixing, and the spectra evolve over time to yield relatively stable substrate-dependent signals at g(iso) approximately 1.980. These signals have been attributed to [Cr(O)L2](L = diolato) species, in which the Cr is coordinated to two cyclized catecholamine ligands and an oxo ligand. Isotopic labeling studies with DOPA (ring or side chain deuteration or enrichment with 15N), and simulation of the signals, show that the superhyperfine couplings originate from the side chain protons, confirming that the catecholamine ligands are cyclized. At pH 3.5, a major short-lived EPR signal is observed for many of the substrates at g(iso) approximately 1.969, but the species responsible for this signal was not identified. Several other minor Cr signals are detected, which are attributed (by comparison with isoelectronic V(IV) species) to Cr(V) complexes coordinated by a single catecholamine ligand (and auxiliary ligands e.g. H2O), or to [Cr(O)L2]- (L = diolato) species with a sixth ligand (e.g. H2O). Addition of catalase or deoxygenation of the solutions did not affect the main EPR signals. When the substrates were in excess (pH &gt; 4.5), primary and secondary (cyclized) semiquinones were also detected. Semiquinone stabilization by Zn(II) complexation yielded stronger EPR signals (g(iso) approximately 2.004).","EPR studies of chromium(V) intermediates generated via reduction of chromium(VI) by DOPA and related catecholamines: potential role for oxidized amino acids in chromium-induced cancers Abs: The reductions of K2Cr2O7 by catecholamines, DOPA, DOPA-beta,beta-d2, N-acetyl-DOPA, alpha-methyl-DOPA, dopamine, adrenaline, noradrenaline, catechol, 1,2-dihydroxybenzoic acid (DHBA), and 4-tert-butylcatechol (TBC), produce a number of Cr(V) electron paramagnetic resonance (EPR) signals. These species are of interest in relation to the potential role of oxidized proteins and amino acids in Cr-induced cancers. With excess organic ligand, all of the substrates yield Cr species with signals at g(iso) approximately 1.972 (Aiso(53Cr) &gt; 23.9 x 10(-4) cm(-1)). These are similar to signals reported previously but have been reassigned as octahedral Cr(V) species with mixed catechol-derived ligands, [CrV(semiquinone)2(catecholate)]+. Experiments with excess K2Cr2O7 show complex behavior with the catecholamines and TBC. Several weak Cr(V) signals are detected after mixing, and the spectra evolve over time to yield relatively stable substrate-dependent signals at g(iso) approximately 1.980. These signals have been attributed to [Cr(O)L2](L = diolato) species, in which the Cr is coordinated to two cyclized catecholamine ligands and an oxo ligand. Isotopic labeling studies with DOPA (ring or side chain deuteration or enrichment with 15N), and simulation of the signals, show that the superhyperfine couplings originate from the side chain protons, confirming that the catecholamine ligands are cyclized. At pH 3.5, a major short-lived EPR signal is observed for many of the substrates at g(iso) approximately 1.969, but the species responsible for this signal was not identified. Several other minor Cr signals are detected, which are attributed (by comparison with isoelectronic V(IV) species) to Cr(V) complexes coordinated by a single catecholamine ligand (and auxiliary ligands e.g. H2O), or to [Cr(O)L2]- (L = diolato) species with a sixth ligand (e.g. H2O). Addition of catalase or deoxygenation of the solutions did not affect the main EPR signals. When the substrates were in excess (pH &gt; 4.5), primary and secondary (cyclized) semiquinones were also detected. Semiquinone stabilization by Zn(II) complexation yielded stronger EPR signals (g(iso) approximately 2.004)."
1234457,Kim et al. 2001,Prurigo pigmentosa from contact allergy to chrome in detergent,"Prurigo pigmentosa is a recurrent inflammatory dermatosis characterized by pruritic erythematous papules and reticulate hyperpigmentation that occurs most frequently in spring and summer. The etiology of prurigo pigmentosa remains unknown. Numerous authors have suggested that various contact allergens may be pathogenic or triggering factors, but nearly all attempts to identify an allergen have been unsuccessful. We report a case of prurigo pigmentosa induced by contact allergy to chrome in detergent, supporting the conclusion that contact allergens such as chrome may play a rôle in inducing prurigo pigmentosa.","Prurigo pigmentosa from contact allergy to chrome in detergent Abs: Prurigo pigmentosa is a recurrent inflammatory dermatosis characterized by pruritic erythematous papules and reticulate hyperpigmentation that occurs most frequently in spring and summer. The etiology of prurigo pigmentosa remains unknown. Numerous authors have suggested that various contact allergens may be pathogenic or triggering factors, but nearly all attempts to identify an allergen have been unsuccessful. We report a case of prurigo pigmentosa induced by contact allergy to chrome in detergent, supporting the conclusion that contact allergens such as chrome may play a rôle in inducing prurigo pigmentosa."
1234456,Moss and  Arrowood 2001,Quantification of Cryptosporidium parvum oocysts in mouse fecal specimens using immunomagnetic particles and two-color flow cytometry,"Although single-color flow cytometry has been shown to be more sensitive than fluorescence microscopy for the quantification of Cryptosporidium parvum oocysts, this method has not been optimized. Monoclonal antibody OW50, specific to the cell wall of oocysts, was conjugated to superparamagnetic particles, to fluorescein isothiocyanate, and to r-phycoerythrin. The oocysts were then double stained with the fluorochrome-labeled OW50 and were placed in tubes with known numbers of highly fluorescent polystyrene beads, allowing quantification of the oocysts without dependence on acquired sample volume by flow cytometry. Data from 2-color flow cytometry using logical gating of the oocysts and beads showed a linear relationship between dilutions of a purified oocyst suspension and the mean numbers of oocysts detected (r2 = 1.00). An average of 15 purified oocysts/ml were counted in a dilution with a theoretical concentration of 12 oocysts/ml. Known numbers of purified oocysts were seeded into normal mouse fecal specimens, captured by OW50-labeled immunomagnetic particles, eluted with 5% potassium dichromate at low pH, and double stained with fluorochrome-labeled OW50. By flow cytometry, the mean recovery was 43.1% (+/-8.3%), and as few as 133 oocysts were detected. The captured and eluted oocysts were infective in neonatal BALB/c mice. This 2-color flow cytometry method, used in conjunction with the capture and elution of oocysts by and from immunomagnetic particles, provides a powerful tool for not only the quantification and purification of C. parvum oocysts from different sources but also for the characterization of oocysts in vitro and in vivo.","Quantification of Cryptosporidium parvum oocysts in mouse fecal specimens using immunomagnetic particles and two-color flow cytometry Abs: Although single-color flow cytometry has been shown to be more sensitive than fluorescence microscopy for the quantification of Cryptosporidium parvum oocysts, this method has not been optimized. Monoclonal antibody OW50, specific to the cell wall of oocysts, was conjugated to superparamagnetic particles, to fluorescein isothiocyanate, and to r-phycoerythrin. The oocysts were then double stained with the fluorochrome-labeled OW50 and were placed in tubes with known numbers of highly fluorescent polystyrene beads, allowing quantification of the oocysts without dependence on acquired sample volume by flow cytometry. Data from 2-color flow cytometry using logical gating of the oocysts and beads showed a linear relationship between dilutions of a purified oocyst suspension and the mean numbers of oocysts detected (r2 = 1.00). An average of 15 purified oocysts/ml were counted in a dilution with a theoretical concentration of 12 oocysts/ml. Known numbers of purified oocysts were seeded into normal mouse fecal specimens, captured by OW50-labeled immunomagnetic particles, eluted with 5% potassium dichromate at low pH, and double stained with fluorochrome-labeled OW50. By flow cytometry, the mean recovery was 43.1% (+/-8.3%), and as few as 133 oocysts were detected. The captured and eluted oocysts were infective in neonatal BALB/c mice. This 2-color flow cytometry method, used in conjunction with the capture and elution of oocysts by and from immunomagnetic particles, provides a powerful tool for not only the quantification and purification of C. parvum oocysts from different sources but also for the characterization of oocysts in vitro and in vivo."
1234455,Acharya et al. 2001,A subtoxic interactive toxicity study of ethanol and chromium in male Wistar rats,"The purpose of this study was to evaluate the interactive toxicity of ethanol with potassium dichromate (K2Cr2O7-chromium). Young, male Wistar rats (100-120 g) were divided into four groups of five or six animals each and were dosed, through water, with 10% ethanol (vol./vol.) or 25 ppm chromium or were dosed with a combination of ethanol+chromium at the same concentrations for a period of 22 weeks ad libitum and were maintained on normal diet. Control animals were maintained on a normal diet and water for the same period. The serum succinate dehydrogenase and liver total triglyceride levels were significantly reduced in the three treated groups. The serum alkaline phosphatase levels were significantly reduced in ethanol-treated rats, and there was no significant change in the acid phosphatase activity. Serum aspartate and alanine aminotransferase levels in the three treated groups were significantly increased. The liver glycogen significantly decreased in both the ethanol-treated and the chromium-treated rats. There was a significant increase in liver total cholesterol levels in chromium-treated rats. Total glutathione levels were significantly decreased in the livers of ethanol-treated and ethanol+chromium-treated rats. To further substantiate these findings, a histological examination of the liver and kidneys was undertaken. The livers of alcohol-treated animals showed altered hepatic architecture in the centrilobular and periportal areas, with increased sinusoidal space (space of Disse), vacuolation, and necrosis of hepatocytes. Similar changes were observed in a histological examination of the livers of chromium-treated rats, except that the damage to the hepatocytes was more confined to the periportal area. Moreover, histological examination of the livers of ethanol+chromium-treated rats revealed uniform damage in the centrilobular and periportal areas, as was observed in the groups treated either with ethanol or chromium. The histological examination of the kidneys in the three treated groups revealed significant damage to the renal tubules and Bowman's capsule, which showed vacuolation and degeneration of the basement membrane. These findings correlate well with the serum enzyme levels found in the treated groups. It is evident from this study that chronic ethanol consumption sensitizes the liver to the toxic action of agents such as chromium. It leads to impairment of the biochemical functions in the liver, and it causes liver and kidney damage. Long-term simultaneous exposure to ethanol and chromium may cause severe health problems in people who are alcoholics and work in chrome-plating and leather-tanning industries.","A subtoxic interactive toxicity study of ethanol and chromium in male Wistar rats Abs: The purpose of this study was to evaluate the interactive toxicity of ethanol with potassium dichromate (K2Cr2O7-chromium). Young, male Wistar rats (100-120 g) were divided into four groups of five or six animals each and were dosed, through water, with 10% ethanol (vol./vol.) or 25 ppm chromium or were dosed with a combination of ethanol+chromium at the same concentrations for a period of 22 weeks ad libitum and were maintained on normal diet. Control animals were maintained on a normal diet and water for the same period. The serum succinate dehydrogenase and liver total triglyceride levels were significantly reduced in the three treated groups. The serum alkaline phosphatase levels were significantly reduced in ethanol-treated rats, and there was no significant change in the acid phosphatase activity. Serum aspartate and alanine aminotransferase levels in the three treated groups were significantly increased. The liver glycogen significantly decreased in both the ethanol-treated and the chromium-treated rats. There was a significant increase in liver total cholesterol levels in chromium-treated rats. Total glutathione levels were significantly decreased in the livers of ethanol-treated and ethanol+chromium-treated rats. To further substantiate these findings, a histological examination of the liver and kidneys was undertaken. The livers of alcohol-treated animals showed altered hepatic architecture in the centrilobular and periportal areas, with increased sinusoidal space (space of Disse), vacuolation, and necrosis of hepatocytes. Similar changes were observed in a histological examination of the livers of chromium-treated rats, except that the damage to the hepatocytes was more confined to the periportal area. Moreover, histological examination of the livers of ethanol+chromium-treated rats revealed uniform damage in the centrilobular and periportal areas, as was observed in the groups treated either with ethanol or chromium. The histological examination of the kidneys in the three treated groups revealed significant damage to the renal tubules and Bowman's capsule, which showed vacuolation and degeneration of the basement membrane. These findings correlate well with the serum enzyme levels found in the treated groups. It is evident from this study that chronic ethanol consumption sensitizes the liver to the toxic action of agents such as chromium. It leads to impairment of the biochemical functions in the liver, and it causes liver and kidney damage. Long-term simultaneous exposure to ethanol and chromium may cause severe health problems in people who are alcoholics and work in chrome-plating and leather-tanning industries."
1234453,Kiss et al. 2001,Role of environmental factors on the reproducibility of Lemna test,"Lemna minor is a species easy to collect and culture in laboratory, and can give rapid test results. However, in order to standardise toxicity tests using Lemna minor as test organism, it is important to find out what natural variability different populations might have. Five Lemna populations were used for comparison. It contained two standard cultures and three populations collected in natural habitats. Potassium dichromate was applied as test material. Lemna populations cultured under the same conditions showed different T(D) and LC50 values. There is an inverse relation between the sensitivity and T(D) of the strains. It is supposed that growth rate and sensitivity of Lemna populations depend on environmental factors characterising the habitat in which the given popluation originally lives.","Role of environmental factors on the reproducibility of Lemna test Abs: Lemna minor is a species easy to collect and culture in laboratory, and can give rapid test results. However, in order to standardise toxicity tests using Lemna minor as test organism, it is important to find out what natural variability different populations might have. Five Lemna populations were used for comparison. It contained two standard cultures and three populations collected in natural habitats. Potassium dichromate was applied as test material. Lemna populations cultured under the same conditions showed different T(D) and LC50 values. There is an inverse relation between the sensitivity and T(D) of the strains. It is supposed that growth rate and sensitivity of Lemna populations depend on environmental factors characterising the habitat in which the given popluation originally lives."
1234452,Kumar 2001,Correlation of plasma color index with serum bilirubin in neonatal jaundice,,Correlation of plasma color index with serum bilirubin in neonatal jaundice Abs: 
1234451,Murki and  Narang 2001,Correlation of plasma color index with serum bilirubin in neonatal jaundice,,Correlation of plasma color index with serum bilirubin in neonatal jaundice Abs: 
1234450,Abou El Naga and  Negm 2001,"Morphology, histochemistry and infectivity of Blastocystis hominis cyst","Different morphological forms of Blastocystis hominis had been identified in human stool samples. These included both cystic and trophic stages. The latter was induced to encyst by keeping them in potassium dichromate solution for two weeks. Suspected of being the infective stage, cysts were studied in more detail as regards their morphology using both light and electron microscopy. Histochemistry and infectivity studies were also carried out. Light microscopy revealed the cysts to be ovoid or round 5-7 microm with thick cyst wall and a single nucleus. The induced cysts were morphologically similar to the cysts present in the stool. By electron microscope, the cyst wall was evident surrounded by an additional fibrillar coat. The cytoplasm contained one nucleus, many mitochondria, glycogen deposits and a number of variable sized vacuoles. Histochemical studies detected carbohydrates in the cyst wall and fat globules in the cytoplasm. Oral inoculation of albino mice with these cysts led to inflammatory changes in the large and small intestine. The parasite was found at the mucosal epithelium but with no invasion. Different forms of the parasite were detected in the lumen of the intestine.","Morphology, histochemistry and infectivity of Blastocystis hominis cyst Abs: Different morphological forms of Blastocystis hominis had been identified in human stool samples. These included both cystic and trophic stages. The latter was induced to encyst by keeping them in potassium dichromate solution for two weeks. Suspected of being the infective stage, cysts were studied in more detail as regards their morphology using both light and electron microscopy. Histochemistry and infectivity studies were also carried out. Light microscopy revealed the cysts to be ovoid or round 5-7 microm with thick cyst wall and a single nucleus. The induced cysts were morphologically similar to the cysts present in the stool. By electron microscope, the cyst wall was evident surrounded by an additional fibrillar coat. The cytoplasm contained one nucleus, many mitochondria, glycogen deposits and a number of variable sized vacuoles. Histochemical studies detected carbohydrates in the cyst wall and fat globules in the cytoplasm. Oral inoculation of albino mice with these cysts led to inflammatory changes in the large and small intestine. The parasite was found at the mucosal epithelium but with no invasion. Different forms of the parasite were detected in the lumen of the intestine."
1234448,Brasch et al. 2001,Patch testing of nickel sulfate and potassium dichromate with a standardized ready-to-use test system gives highly reproducible results: a double-blind multicentre study,"There is still some doubt about the reproducibility of patch tests. A sound assessment needs optimized and unbiased studies. This study analysed the results of a double-blind multicentre study with nickel sulfate and potassium dichromate patch tests attached synchronously to both sides of the back of patients with a history of nickel allergy, conducted with a highly standardized randomized test system (TRUE-test). Out of 589 patients tested, a total of 388 had responded with allergic reactions to nickel sulfate and 130 to potassium dichromate. The reproducibility of positive nickel (dichromate) patch tests was 99.2% (90.8%). The reaction index was also calculated, which relates the number of allergic reactions obtained with a test preparation to the number of questionable and irritant reactions; the reaction index can range from -1 (questionable and irritant reactions only occur) to 1 (allergic reactions only occur). For nickel sulfate the reaction index was 0.91, but it was only 0.23 for potassium dichromate, as a result of considerably more questionable reactions. In conclusion, a highly synchronous reproducibility of results can be achieved by using a well-standardized patch-test system, especially with nickel sulfate. However, distinct allergens and test systems need to be evaluated separately.","Patch testing of nickel sulfate and potassium dichromate with a standardized ready-to-use test system gives highly reproducible results: a double-blind multicentre study Abs: There is still some doubt about the reproducibility of patch tests. A sound assessment needs optimized and unbiased studies. This study analysed the results of a double-blind multicentre study with nickel sulfate and potassium dichromate patch tests attached synchronously to both sides of the back of patients with a history of nickel allergy, conducted with a highly standardized randomized test system (TRUE-test). Out of 589 patients tested, a total of 388 had responded with allergic reactions to nickel sulfate and 130 to potassium dichromate. The reproducibility of positive nickel (dichromate) patch tests was 99.2% (90.8%). The reaction index was also calculated, which relates the number of allergic reactions obtained with a test preparation to the number of questionable and irritant reactions; the reaction index can range from -1 (questionable and irritant reactions only occur) to 1 (allergic reactions only occur). For nickel sulfate the reaction index was 0.91, but it was only 0.23 for potassium dichromate, as a result of considerably more questionable reactions. In conclusion, a highly synchronous reproducibility of results can be achieved by using a well-standardized patch-test system, especially with nickel sulfate. However, distinct allergens and test systems need to be evaluated separately."
1234447,Ensafi et al. 2001,Kinetic spectrophotometric method for the determination of oxalic acid by its catalytic effect on the oxidation of safranine by dichromate,"A new catalytic kinetic spectrophotometric method for the determination of oxalic acid has been described based on its catalytic effect on the redox reaction between safranine and dichromate in dilute sulfuric acid media. The reaction is monitored photometrically by measuring the decrease in absorbance of safranine at the maximum wavelength of 530 nm. Under the optimum conditions, a calibration graph from 0.10 to 10.00 microg ml(-1) of oxalic acid with a detection limit of 0.08 microg ml(-1) was obtained. The relative standard deviation (R.S.D.) for ten replicate measurements of 1.0 and 5.0 microg ml(-1) oxalic acid was 2.7 and 2.5%, respectively. The purposed method is simple, sensitive, selective and inexpensive. The applicability of the proposed method was determined by the determination of oxalic acid in spinach and wastewater samples with satisfactory results.","Kinetic spectrophotometric method for the determination of oxalic acid by its catalytic effect on the oxidation of safranine by dichromate Abs: A new catalytic kinetic spectrophotometric method for the determination of oxalic acid has been described based on its catalytic effect on the redox reaction between safranine and dichromate in dilute sulfuric acid media. The reaction is monitored photometrically by measuring the decrease in absorbance of safranine at the maximum wavelength of 530 nm. Under the optimum conditions, a calibration graph from 0.10 to 10.00 microg ml(-1) of oxalic acid with a detection limit of 0.08 microg ml(-1) was obtained. The relative standard deviation (R.S.D.) for ten replicate measurements of 1.0 and 5.0 microg ml(-1) oxalic acid was 2.7 and 2.5%, respectively. The purposed method is simple, sensitive, selective and inexpensive. The applicability of the proposed method was determined by the determination of oxalic acid in spinach and wastewater samples with satisfactory results."
1234446,Spanó et al. 2001,Recombinagenic activity of four compounds in the standard and high bioactivation crosses of Drosophila melanogaster in the wing spot test,"The wing somatic mutation and recombination test (SMART) using Drosophila melanogaster was employed to determine the recombinagenic and mutagenic activity of four chemicals in an in vivo eukaryotic system. Two different crosses involving the wing cell markers mwh and flr(3) were used: the standard cross and a high bioactivation cross. The high bioactivation cross is characterized by a high constitutive level of cytochromes P450 which leads to an increased sensitivity to a number of promutagens and procarcinogens. Three-day-old larvae derived from both crosses were treated chronically with the oxidizing agent potassium chromate and with the three procarcinogens cyclophosphamide, p-dimethylaminoazobenzene and 9,10-dimethylanthracene. From both crosses two types of progeny were obtained: marker-heterozygous and balancer-heterozygous. The wings of both genotypes were analysed for the occurrence of single and twin spots expressing the mwh and/or flr(3) mutant phenotypes. In the marker-heterozygous genotype the spots can be due either to mitotic recombination or to mutation. In contrast, in the balancer-heterozygous genotype only mutational events lead to spot formation, all recombination events being eliminated. The oxidizing agent potassium chromate was equally and highly genotoxic in both crosses. Surprisingly, the promutagen cyclophosphamide also showed equal genotoxicity in both crosses, whereas p-dimethylaminoazobenzene was negative in the standard cross, but clearly genotoxic in the high bioactivation cross. 9,10-Dimethylanthracene showed a rather weak genotoxicity in the high bioactivation cross. Analyses of the dose-response relationships for mwh clones recorded in the two wing genotypes demonstrated that all four compounds are recombinagenic. The fraction of all genotoxic events which are due to mitotic recombination ranged from 83% (9,10-dimethylanthracene) to 99% (p-dimethylaminoazobenzene). These results demonstrate that the wing spot test in Drosophila is most suited to the detection of recombinagenic activity of genotoxic chemicals.","Recombinagenic activity of four compounds in the standard and high bioactivation crosses of Drosophila melanogaster in the wing spot test Abs: The wing somatic mutation and recombination test (SMART) using Drosophila melanogaster was employed to determine the recombinagenic and mutagenic activity of four chemicals in an in vivo eukaryotic system. Two different crosses involving the wing cell markers mwh and flr(3) were used: the standard cross and a high bioactivation cross. The high bioactivation cross is characterized by a high constitutive level of cytochromes P450 which leads to an increased sensitivity to a number of promutagens and procarcinogens. Three-day-old larvae derived from both crosses were treated chronically with the oxidizing agent potassium chromate and with the three procarcinogens cyclophosphamide, p-dimethylaminoazobenzene and 9,10-dimethylanthracene. From both crosses two types of progeny were obtained: marker-heterozygous and balancer-heterozygous. The wings of both genotypes were analysed for the occurrence of single and twin spots expressing the mwh and/or flr(3) mutant phenotypes. In the marker-heterozygous genotype the spots can be due either to mitotic recombination or to mutation. In contrast, in the balancer-heterozygous genotype only mutational events lead to spot formation, all recombination events being eliminated. The oxidizing agent potassium chromate was equally and highly genotoxic in both crosses. Surprisingly, the promutagen cyclophosphamide also showed equal genotoxicity in both crosses, whereas p-dimethylaminoazobenzene was negative in the standard cross, but clearly genotoxic in the high bioactivation cross. 9,10-Dimethylanthracene showed a rather weak genotoxicity in the high bioactivation cross. Analyses of the dose-response relationships for mwh clones recorded in the two wing genotypes demonstrated that all four compounds are recombinagenic. The fraction of all genotoxic events which are due to mitotic recombination ranged from 83% (9,10-dimethylanthracene) to 99% (p-dimethylaminoazobenzene). These results demonstrate that the wing spot test in Drosophila is most suited to the detection of recombinagenic activity of genotoxic chemicals."
1234444,Das Neves et al. 2001,Chromium(VI) induced alterations in mouse spleen cells: a short-term assay,"Cr(VI), the highest oxidation state for chromium, is a carcinogenic and mutagenic agent. In vivo and in vitro Cr(VI) toxic effects are related to its intracellular fate. Once inside the cell it is reduced to stable Cr(III) by cysteine, glutathione and ascorbic acid. Additionally, as Cr(V) and/or Cr(IV) intermediates have been reported in Cr(VI) reactions with biological reductants, chromium damage is thought to originate from these chemical species. This work investigated the morphology of splenic cells after short-term exposure to Cr(VI). A dose of 30 mg of K2CrO4/kg body weight was administered to mice and the effects were studied 24 and 48 h after the injections. Histological results revealed a time-dependency effect of Cr(VI) on splenic cells. Changes included enlargement of the capsule and depletion of the red pulp cells, accompanied by an increase in macrophages, 24 h after injection. Partial restoration of red pulp was noted after 48 h.","Chromium(VI) induced alterations in mouse spleen cells: a short-term assay Abs: Cr(VI), the highest oxidation state for chromium, is a carcinogenic and mutagenic agent. In vivo and in vitro Cr(VI) toxic effects are related to its intracellular fate. Once inside the cell it is reduced to stable Cr(III) by cysteine, glutathione and ascorbic acid. Additionally, as Cr(V) and/or Cr(IV) intermediates have been reported in Cr(VI) reactions with biological reductants, chromium damage is thought to originate from these chemical species. This work investigated the morphology of splenic cells after short-term exposure to Cr(VI). A dose of 30 mg of K2CrO4/kg body weight was administered to mice and the effects were studied 24 and 48 h after the injections. Histological results revealed a time-dependency effect of Cr(VI) on splenic cells. Changes included enlargement of the capsule and depletion of the red pulp cells, accompanied by an increase in macrophages, 24 h after injection. Partial restoration of red pulp was noted after 48 h."
1234443,de Lucca C Preza and  Smith 2001,"Use of newborn Girardia tigrina (Girard, 1850) in acute toxicity tests","Acute toxicity tests, exposing Girardia tigrina to potassium dichromate (K(2)Cr(2)O(7)), showed good reproducibility. The 95% confidence intervals among tests were 0.0262+/-0.0141 g for 48-h LC(50) (N=6) and 0.0129+/-0.0078 g for 96-h LC(50) (N=5). The 96-h LC(50) for G. tigrina was below that of oligochaetes and above that of cladocera.","Use of newborn Girardia tigrina (Girard, 1850) in acute toxicity tests Abs: Acute toxicity tests, exposing Girardia tigrina to potassium dichromate (K(2)Cr(2)O(7)), showed good reproducibility. The 95% confidence intervals among tests were 0.0262+/-0.0141 g for 48-h LC(50) (N=6) and 0.0129+/-0.0078 g for 96-h LC(50) (N=5). The 96-h LC(50) for G. tigrina was below that of oligochaetes and above that of cladocera."
1234442,Choi et al. 2001,"Hypoxia, hyperoxia and exposure to potassium dichromate or fenitrothion alter the energy metabolism in Chironomus riparius Mg. (Diptera: Chironomidae) larvae","Short-term (24 h) effects of four stressors (hypoxia, hyperoxia, potassium dichromate, fenitrothion) on the activity of the electron transport system (ETS) and total lipid, glycogen and protein contents were assessed in 4th instar larvae of Chironomus riparius. Hypoxia and hyperoxia caused an increase in ETS activity and protein content. Glycogen content decreased when larvae were placed under hypoxic conditions. ETS activity increased following exposure to 2 microg x l(-1) of fenitrothion. It decreased in larvae exposed to 20 microg x l(-1) of this insecticide. A decrease in lipid and glycogen contents was observed in larvae exposed to potassium dichromate or fenitrothion. Changes in ETS activity and lipid and glycogen contents may be related to the activation of the respiratory chain due to an increase in energy cost associated with homeostatic phenomena, such as detoxification processes. These results suggest that some parameters related to energy metabolism, such as ETS activity and lipid and glycogen contents, may be used as biomarkers of environmental disturbance in Chironomus riparius larvae.","Hypoxia, hyperoxia and exposure to potassium dichromate or fenitrothion alter the energy metabolism in Chironomus riparius Mg. (Diptera: Chironomidae) larvae Abs: Short-term (24 h) effects of four stressors (hypoxia, hyperoxia, potassium dichromate, fenitrothion) on the activity of the electron transport system (ETS) and total lipid, glycogen and protein contents were assessed in 4th instar larvae of Chironomus riparius. Hypoxia and hyperoxia caused an increase in ETS activity and protein content. Glycogen content decreased when larvae were placed under hypoxic conditions. ETS activity increased following exposure to 2 microg x l(-1) of fenitrothion. It decreased in larvae exposed to 20 microg x l(-1) of this insecticide. A decrease in lipid and glycogen contents was observed in larvae exposed to potassium dichromate or fenitrothion. Changes in ETS activity and lipid and glycogen contents may be related to the activation of the respiratory chain due to an increase in energy cost associated with homeostatic phenomena, such as detoxification processes. These results suggest that some parameters related to energy metabolism, such as ETS activity and lipid and glycogen contents, may be used as biomarkers of environmental disturbance in Chironomus riparius larvae."
1234441,García-Rodríguez et al. 2001,Effect of chlorophyllin on chromium trioxide-induced micronuclei in polychromatic erythrocytes in mouse peripheral blood,"The effect of chlorophyllin on micronucleated polychromatic erythrocytes (MN-PCE) induction by chromium trioxide (CrO(3)) exposure in peripheral blood of mice was studied. Animals were treated with a single intraperitoneal dose of chlorophyllin (CHL) (20mg/kg), CrO(3) (20mg/kg), and CHL (20mg/kg) 4h before (CHL-CrO(3)) or 4h before and 20h after chromium treatments (20mg/kg; CHL-CrO(3)-CHL). Peripheral blood samples were drawn from the caudal vein at 0, 12 and 48h, and analyzed by the acridine orange (AO) technique. The results obtained in present study shown that CHL injection did not modify the number of MN-PCE. CrO(3) treatment resulted in a significantly increases 12 and 48h after the injection, reaching a four-fold increase 48h after CrO(3) administration. Whereas treatment with 20mg/kg of CHL prior to chromium, decreased the MN frequency induced by chromium in the 12h samples. When the samples were analyzed 48h after CrO(3) injection, no significant differences between CHL-CrO(3) and CHL-CrO(3)-CHL in comparison with CrO(3) treatment, were observed. These results indicate that increase of MN-PCE by CrO(3) is CHL-blocked in both protocols used (CHL-CrO(3) and CHL-CrO(3)-CHL) at 12h after treatment, but it was unable to modify the frequency of MN-PCE measured 48h after CrO(3) injection. The absence of a protective effect by CHL in the MN-PCE induction by CrO(3) at 48h, show that CHL has action only on one of the times of MN induction and suggests the possible action of CrO(3) by two different mechanisms, and not by CHL time-limited in vivo.","Effect of chlorophyllin on chromium trioxide-induced micronuclei in polychromatic erythrocytes in mouse peripheral blood Abs: The effect of chlorophyllin on micronucleated polychromatic erythrocytes (MN-PCE) induction by chromium trioxide (CrO(3)) exposure in peripheral blood of mice was studied. Animals were treated with a single intraperitoneal dose of chlorophyllin (CHL) (20mg/kg), CrO(3) (20mg/kg), and CHL (20mg/kg) 4h before (CHL-CrO(3)) or 4h before and 20h after chromium treatments (20mg/kg; CHL-CrO(3)-CHL). Peripheral blood samples were drawn from the caudal vein at 0, 12 and 48h, and analyzed by the acridine orange (AO) technique. The results obtained in present study shown that CHL injection did not modify the number of MN-PCE. CrO(3) treatment resulted in a significantly increases 12 and 48h after the injection, reaching a four-fold increase 48h after CrO(3) administration. Whereas treatment with 20mg/kg of CHL prior to chromium, decreased the MN frequency induced by chromium in the 12h samples. When the samples were analyzed 48h after CrO(3) injection, no significant differences between CHL-CrO(3) and CHL-CrO(3)-CHL in comparison with CrO(3) treatment, were observed. These results indicate that increase of MN-PCE by CrO(3) is CHL-blocked in both protocols used (CHL-CrO(3) and CHL-CrO(3)-CHL) at 12h after treatment, but it was unable to modify the frequency of MN-PCE measured 48h after CrO(3) injection. The absence of a protective effect by CHL in the MN-PCE induction by CrO(3) at 48h, show that CHL has action only on one of the times of MN induction and suggests the possible action of CrO(3) by two different mechanisms, and not by CHL time-limited in vivo."
1234439,Basavaiah and  Swamy 2001,Application of potassium dichromate and iron-thiocyanate in the spectrophotometric investigations of phenothiazines,"A spectrophotometric procedure for the determination of phenothiazines in pure form and in a number of their pharmaceutical preparations has been developed that offers the advantages of simplicity, accuracy, precision and sensitivity over many other methods. The method is based on the oxidation of phenothiazines by a known excess amount of potassium dichromate followed by the estimation of unreacted amount of dichromate by reacting with excess of iron(II) and measuring the iron(III) formed by complexing with thiocyanate. The reacted oxidant corresponds to the drug content. Different variables affecting the reaction between drugs and dichromate were studied and optimized. At the maximum absorption of 480 nm, Beer's law is obeyed in the range 2.5-29.75 microg/ml. The molar absorptivity and Sandell sensitivity of the procedure were calculated in addition to detection limit. Statistical treatment of the experimental results indicates that the procedure is precise and accurate. Excipients used as additives in pharmaceutical formulations did not interfere in the proposed procedure. The reliability of the method was established by parallel determination against the official BP methods. The procedure described was successfully applied to the determination of the bulk drugs and in pharmaceutical formulations.","Application of potassium dichromate and iron-thiocyanate in the spectrophotometric investigations of phenothiazines Abs: A spectrophotometric procedure for the determination of phenothiazines in pure form and in a number of their pharmaceutical preparations has been developed that offers the advantages of simplicity, accuracy, precision and sensitivity over many other methods. The method is based on the oxidation of phenothiazines by a known excess amount of potassium dichromate followed by the estimation of unreacted amount of dichromate by reacting with excess of iron(II) and measuring the iron(III) formed by complexing with thiocyanate. The reacted oxidant corresponds to the drug content. Different variables affecting the reaction between drugs and dichromate were studied and optimized. At the maximum absorption of 480 nm, Beer's law is obeyed in the range 2.5-29.75 microg/ml. The molar absorptivity and Sandell sensitivity of the procedure were calculated in addition to detection limit. Statistical treatment of the experimental results indicates that the procedure is precise and accurate. Excipients used as additives in pharmaceutical formulations did not interfere in the proposed procedure. The reliability of the method was established by parallel determination against the official BP methods. The procedure described was successfully applied to the determination of the bulk drugs and in pharmaceutical formulations."
1234438,Mazzarello 1999,Camillo Golgi's scientific biography,"Born in Corteno, a tiny village in the province of Brescia, Camillo Golgi studied at the University of Pavia where he graduated in medicine in 1865 under the guidance of the psychiatrist Cesare Lombroso who sparked his vocation to study the brain. Golgi then began to learn histological techniques under the direction of the pathologist Giulio Bizzozero. In 1872 he moved to Abbiategrasso as chief of a hospital for chronic diseases. In a rudimentary laboratory he developed the silver-bichromate staining technique, the 'black reaction', which was a breakthrough for nervous tissue structure research. While in Abbiategrasso Golgi demonstrated the branching of the axons, and observed striatal and cortical lesions in a case of chorea. He returned to Pavia as Professor of Histology and General Pathology, and made a series of important discoveries that still bear his name: the Golgi tendon organ, the Golgi-Mazzoni corpuscles, another Golgi method to stain nerve cells based on the use of potassium dichromate and mercuric chloride, the canaliculi of the parietal cells of the gastric glands (Muller-Golgi tubules), the Golgi-Rezzonico myelin's annular apparatus (or Golgi-Rezzonico horny funnels), the cycle of malarian parasites (Golgi cycle), the relationship between recurrent malarian fever bouts and the multiplication of the Plasmodium in the blood (Golgi law), the relationship between the vascular pole of the Malpighian glomerulus and the distal tubule, the Golgi's pericellular nets and finally, and most importantly, the cytoplasmic 'internal reticular apparatus' (Golgi apparatus). In 1906 Golgi was awarded the Nobel prize for Medicine or Physiology. He died in Pavia on 21 January 1921.","Camillo Golgi's scientific biography Abs: Born in Corteno, a tiny village in the province of Brescia, Camillo Golgi studied at the University of Pavia where he graduated in medicine in 1865 under the guidance of the psychiatrist Cesare Lombroso who sparked his vocation to study the brain. Golgi then began to learn histological techniques under the direction of the pathologist Giulio Bizzozero. In 1872 he moved to Abbiategrasso as chief of a hospital for chronic diseases. In a rudimentary laboratory he developed the silver-bichromate staining technique, the 'black reaction', which was a breakthrough for nervous tissue structure research. While in Abbiategrasso Golgi demonstrated the branching of the axons, and observed striatal and cortical lesions in a case of chorea. He returned to Pavia as Professor of Histology and General Pathology, and made a series of important discoveries that still bear his name: the Golgi tendon organ, the Golgi-Mazzoni corpuscles, another Golgi method to stain nerve cells based on the use of potassium dichromate and mercuric chloride, the canaliculi of the parietal cells of the gastric glands (Muller-Golgi tubules), the Golgi-Rezzonico myelin's annular apparatus (or Golgi-Rezzonico horny funnels), the cycle of malarian parasites (Golgi cycle), the relationship between recurrent malarian fever bouts and the multiplication of the Plasmodium in the blood (Golgi law), the relationship between the vascular pole of the Malpighian glomerulus and the distal tubule, the Golgi's pericellular nets and finally, and most importantly, the cytoplasmic 'internal reticular apparatus' (Golgi apparatus). In 1906 Golgi was awarded the Nobel prize for Medicine or Physiology. He died in Pavia on 21 January 1921."
1234437,Trevisan et al. 2001,Tubular segment-specific biomarkers of nephrotoxicity in the rat,"Segment-specific localization of p-aminohippuric acid accumulation and glutamine synthetase activity along the proximal tubule was investigated in kidneys of rats treated with segment-specific nephrotoxicants such as potassium dichromate (pars convoluta) and hexachloro-1:3-butadiene (pars recta). Potassium dichromate and the highest dose (200 mg/kg b.w.) of hexachloro-1:3-butadiene caused a significant, dose-dependent decrease of p-aminohippuric acid uptake in the renal cortical slices 24 and 48 h after the treatment. In contrast, hexachloro-1:3-butadiene and only the highest dose (40 mg/kg b.w.) of potassium dichromate, caused a significant dose-dependent decrease of glutamine synthetase activity in the kidney beginning 24 h after treatment. Finally, potassium dichromate and the highest dose (200 mg/kg b.w.) of hexachloro-1:3-butadiene (48 h after the treatment) caused a significant dose-dependent loss of kidney protein content. The results suggest that p-aminohippuric acid accumulation is localized in the pars convoluta and confirm that glutamine synthetase is in the pars recta of the rat proximal tubule. p-Aminohippuric acid uptake impairment and glutamine synthetase activity loss caused by the highest doses of hexachloro-1:3-butadiene and potassium dichromate, respectively, suggests that high doses of segment-specific chemicals may involve other portions of the proximal tubule; in addition, the decrease of glutamine synthetase activity caused by potassium dichromate may be related to the protein content loss.","Tubular segment-specific biomarkers of nephrotoxicity in the rat Abs: Segment-specific localization of p-aminohippuric acid accumulation and glutamine synthetase activity along the proximal tubule was investigated in kidneys of rats treated with segment-specific nephrotoxicants such as potassium dichromate (pars convoluta) and hexachloro-1:3-butadiene (pars recta). Potassium dichromate and the highest dose (200 mg/kg b.w.) of hexachloro-1:3-butadiene caused a significant, dose-dependent decrease of p-aminohippuric acid uptake in the renal cortical slices 24 and 48 h after the treatment. In contrast, hexachloro-1:3-butadiene and only the highest dose (40 mg/kg b.w.) of potassium dichromate, caused a significant dose-dependent decrease of glutamine synthetase activity in the kidney beginning 24 h after treatment. Finally, potassium dichromate and the highest dose (200 mg/kg b.w.) of hexachloro-1:3-butadiene (48 h after the treatment) caused a significant dose-dependent loss of kidney protein content. The results suggest that p-aminohippuric acid accumulation is localized in the pars convoluta and confirm that glutamine synthetase is in the pars recta of the rat proximal tubule. p-Aminohippuric acid uptake impairment and glutamine synthetase activity loss caused by the highest doses of hexachloro-1:3-butadiene and potassium dichromate, respectively, suggests that high doses of segment-specific chemicals may involve other portions of the proximal tubule; in addition, the decrease of glutamine synthetase activity caused by potassium dichromate may be related to the protein content loss."
1234435,Higgins et al. 2001,Real-time PCR for the detection of Cryptosporidium parvum,"Real time, TaqMan PCR assays were developed for the Cp11 and 18S rRNA genes of the protozoan parasite Cryptosporidium parvum. The TaqMan probes were specific for the genus Cryptosporidium, but could not hybridize exclusively with human-infectious C. parvum species and genotypes. In conjunction with development of the TaqMan assays, two commercial kits, the Mo Bio UltraClean Soil DNA kit, and the Qiagen QIAamp DNA Stool kit, were evaluated for DNA extraction from calf diarrhea and manure, and potassium dichromate and formalin preserved human feces. Real-time quantitation was achieved with the diarrhea samples, but nested PCR was necessary to detect C. parvum DNA in manure and human feces. Ileal tissues were obtained from calves at 3, 7, and 14 days post-infection, and DNA extracted and assayed. Nested PCR detected C. parvum DNA in the 7-day post-infection sample, but neither of the other time point samples were positive. These results indicate that real-time quantitation of C. parvum DNA, extracted using the commercial kits, is feasible on diarrheic feces, with large numbers of oocysts and small concentrations of PCR inhibitor(s). For samples with few oocysts and high concentrations of PCR inhibitor(s), such as manure, nested PCR is necessary for detection.","Real-time PCR for the detection of Cryptosporidium parvum Abs: Real time, TaqMan PCR assays were developed for the Cp11 and 18S rRNA genes of the protozoan parasite Cryptosporidium parvum. The TaqMan probes were specific for the genus Cryptosporidium, but could not hybridize exclusively with human-infectious C. parvum species and genotypes. In conjunction with development of the TaqMan assays, two commercial kits, the Mo Bio UltraClean Soil DNA kit, and the Qiagen QIAamp DNA Stool kit, were evaluated for DNA extraction from calf diarrhea and manure, and potassium dichromate and formalin preserved human feces. Real-time quantitation was achieved with the diarrhea samples, but nested PCR was necessary to detect C. parvum DNA in manure and human feces. Ileal tissues were obtained from calves at 3, 7, and 14 days post-infection, and DNA extracted and assayed. Nested PCR detected C. parvum DNA in the 7-day post-infection sample, but neither of the other time point samples were positive. These results indicate that real-time quantitation of C. parvum DNA, extracted using the commercial kits, is feasible on diarrheic feces, with large numbers of oocysts and small concentrations of PCR inhibitor(s). For samples with few oocysts and high concentrations of PCR inhibitor(s), such as manure, nested PCR is necessary for detection."
1234433,Morrow et al. 2001,Development of a bioassay for phytochemicals using Daphnia pulex,"The freshwater cladoceran Daphnia pulex was explored as an alternative to Artemia salina for the biological screening of phytochemicals. This paper reports on the results of screening 27 compounds, and comparisons are made with screens using Artemia salina. The effect of miniaturisation of the assay system was investigated. Petri-dish based tests were performed for the 27 compounds using 10 daphnids at each of 5 concentrations (1 - 1000 mg l(-1)). Potassium dichromate was used as a control and the number immobile after 24 hours were counted. Results were expressed as EC(50) values. The active compounds (EC(50) &lt; 25 mg l(-1)) comprised mainly adrenoceptor agonist alkaloids, while the cytotoxins vincristine and colchicine, and several antibiotics were relatively non-toxic towards Daphnia. The method was validated by comparative bioassay of A. belladonna fractions. Overall, this screen compared favourably with those based on Artemia. Daphnia were sensitive to a wide range of biologically active molecules including CNS-stimulants, anti-malarials, narcotics and anti-spasmodics, and the sensitivity was broader than previously seen with Artemia. The screen is perhaps limited by the lack of sensitivity to cytotoxins, but this might be overcome by altering the test criteria.","Development of a bioassay for phytochemicals using Daphnia pulex Abs: The freshwater cladoceran Daphnia pulex was explored as an alternative to Artemia salina for the biological screening of phytochemicals. This paper reports on the results of screening 27 compounds, and comparisons are made with screens using Artemia salina. The effect of miniaturisation of the assay system was investigated. Petri-dish based tests were performed for the 27 compounds using 10 daphnids at each of 5 concentrations (1 - 1000 mg l(-1)). Potassium dichromate was used as a control and the number immobile after 24 hours were counted. Results were expressed as EC(50) values. The active compounds (EC(50) &lt; 25 mg l(-1)) comprised mainly adrenoceptor agonist alkaloids, while the cytotoxins vincristine and colchicine, and several antibiotics were relatively non-toxic towards Daphnia. The method was validated by comparative bioassay of A. belladonna fractions. Overall, this screen compared favourably with those based on Artemia. Daphnia were sensitive to a wide range of biologically active molecules including CNS-stimulants, anti-malarials, narcotics and anti-spasmodics, and the sensitivity was broader than previously seen with Artemia. The screen is perhaps limited by the lack of sensitivity to cytotoxins, but this might be overcome by altering the test criteria."
1234432,Andersen et al. 2001,Development of copepod nauplii to copepodites--a parameter for chronic toxicity including endocrine disruption,"Test compounds including natural hormones, endocrine disrupters, environmentally occurring compounds, and reference compounds were tested for acute toxicity and inhibitory effect on larval development in the copepod Acartia tonsa. Three compounds, 17alpha-ethinylestradiol, p-octylphenol, and tamoxifen, known for their differing effects on the vertebrate estrogen system, were potent inhibitors of naupliar development. Other estrogens, 17beta-estradiol, estrone, and bisphenol A, had little potency. Testosterone and progesterone did not inhibit development, but the antiandrogen flutamide had inhibitory effect. Juvenile hormone III was a potent inhibitor, as was expected based on the literature, whereas 20-hydroxyecdysone had no effect. 3,4-Dichloroaniline was inhibitory on development, whereas other control compounds, potassium dichromate and 3,5-dichlorophenol, did not inhibit development. Six of the 17 test compounds had 50% lethal concentration to 50% effective concentration (EC50) ratios higher than 10. The results suggest that naupliar development, as a parameter, is able to detect hormonal disrupters in addition to other chemicals that have other specific modes of action.","Development of copepod nauplii to copepodites--a parameter for chronic toxicity including endocrine disruption Abs: Test compounds including natural hormones, endocrine disrupters, environmentally occurring compounds, and reference compounds were tested for acute toxicity and inhibitory effect on larval development in the copepod Acartia tonsa. Three compounds, 17alpha-ethinylestradiol, p-octylphenol, and tamoxifen, known for their differing effects on the vertebrate estrogen system, were potent inhibitors of naupliar development. Other estrogens, 17beta-estradiol, estrone, and bisphenol A, had little potency. Testosterone and progesterone did not inhibit development, but the antiandrogen flutamide had inhibitory effect. Juvenile hormone III was a potent inhibitor, as was expected based on the literature, whereas 20-hydroxyecdysone had no effect. 3,4-Dichloroaniline was inhibitory on development, whereas other control compounds, potassium dichromate and 3,5-dichlorophenol, did not inhibit development. Six of the 17 test compounds had 50% lethal concentration to 50% effective concentration (EC50) ratios higher than 10. The results suggest that naupliar development, as a parameter, is able to detect hormonal disrupters in addition to other chemicals that have other specific modes of action."
1234431,Pourahmad et al. 2001,Hepatocyte lysis induced by environmental metal toxins may involve apoptotic death signals initiated by mitochondrial injury,"Addition of CdCl2, HgCl2 or K2Cr2O7 to isolated hepatocytes caused a rapid increase in reactive oxygen species (""ROS"") formation and a decline in mitochondrial membrane potential. Later lipid peroxidation and cell lysis ensued. Cytotoxicity was prevented by ""ROS"" scavengers and various inhibitors of the mitochondrial permeability transition (MPT) eg. cyclosporin A, carnitine or trifluoperazine. Antioxidants prevented hepatocyte lysis induced by CdCl2, K2Cr2O7 but not HgCl2. Hepatocyte lysis was also prevented by various apoptosis inhibitors eg, cycloheximide, dactinomycin and a tetrapeptide caspase 3 inhibitor which suggests that metal induced hepatocyte lysis involves apoptotic death signals initiated by MPT and ""ROS"".","Hepatocyte lysis induced by environmental metal toxins may involve apoptotic death signals initiated by mitochondrial injury Abs: Addition of CdCl2, HgCl2 or K2Cr2O7 to isolated hepatocytes caused a rapid increase in reactive oxygen species (""ROS"") formation and a decline in mitochondrial membrane potential. Later lipid peroxidation and cell lysis ensued. Cytotoxicity was prevented by ""ROS"" scavengers and various inhibitors of the mitochondrial permeability transition (MPT) eg. cyclosporin A, carnitine or trifluoperazine. Antioxidants prevented hepatocyte lysis induced by CdCl2, K2Cr2O7 but not HgCl2. Hepatocyte lysis was also prevented by various apoptosis inhibitors eg, cycloheximide, dactinomycin and a tetrapeptide caspase 3 inhibitor which suggests that metal induced hepatocyte lysis involves apoptotic death signals initiated by MPT and ""ROS""."
1234430,Belsito et al. 2002,Allergic contact dermatitis to detergents: a multicenter study to assess prevalence,"<strong>BACKGROUND: </strong>Allergic contact dermatitis (ACD) to optical brighteners and enzymes in laundry detergents was the focus of numerous reports in the early 1970s. Subsequently, there has been little published on the incidence of allergic reactions to chemicals in laundry detergents. Nonetheless, consumers and physicians continue to ascribe allergic contact reactions to laundry detergents.<br /><br /><strong>OBJECTIVE: </strong>This article reports the findings of a multicenter study on the prevalence of patch test reactions to a liquid and a granular laundry detergent provided by Procter &amp; Gamble Company (Cincinnati, Ohio).<br /><br /><strong>METHODS: </strong>Patients referred to members of the North American Contact Dermatitis Group for evaluation of potential ACD were invited to participate in the study, which involved the placement of 2 patch tests (a 0.1% aqueous dilution of a granular laundry detergent and a 0.1% aqueous dilution of a liquid laundry detergent). Whether the patients had atopic dermatitis and whether they or their physicians felt that their dermatitis might be related to laundry detergents were noted. Reactions to the laundry detergents were correlated with allergic reactions to the following screening chemicals: fragrances, nickel, and potassium dichromate. Patients who experienced a reaction to at least one of the laundry detergents could enter phase II of the study, which involved testing to varying dilutions of the laundry detergents, to 0.1% sodium lauryl sulfate (as an irritant control), and to laundered patches of cotton. Patients positive in phase II could enter phase III, which involved wearing a garment laundered with the detergent. Phases II and III were double blinded.<br /><br /><strong>RESULTS: </strong>Of the 3120 patients seen by members of the North American Contact Dermatitis Group during the 2 years of this study, 738 patients volunteered to enroll. Enrollment was not statistically randomized. Of these 738, 5 (0.7%) had positive patch test reactions to granular laundry detergent (0.1%, aqueous); 3 of these 5 also had positive reactions to the liquid laundry detergent (0.1%, aqueous). In 4 of the 5 patients, the reaction to detergent was thought to have present relevance to their dermatitis; in 1 of the 5, the reaction was deemed to have past relevance. One of these 5 patients had allergy to fragrances. None of the patients was positive to nickel or chromate. Two of the 5 entered phases II and III. Of these 2 patients, 1 had essentially negative repeat dilutional patch testing and &quot;use testing&quot; suggesting that the earlier reaction patterns may have been irritant. The remaining patient had positive dilutional reactions to both the liquid and granular laundry detergent; however, she also had a positive reaction to sodium lauryl sulfate and to a swatch from a T-shirt laundered without detergent. Upon &quot;use testing&quot; in phase III, this latter patient experienced diffuse dermatitis under both the half of the T-shirt laundered with detergent and that laundered without detergent.<br /><br /><strong>CONCLUSION: </strong>Laundry detergents appear to be a rare cause of ACD. Among 738 patients with dermatitis, 5 (0.7%) reacted to a 0.1% aqueous dilution of a laundry detergent. Only 2 of these 5 patients could be evaluated in greater detail to differentiate allergic from irritant patch test reactions to detergents. Upon further testing in 2 patients, the reaction in 1 of 2 could not be reduplicated and the reaction in the other was invoked both by the detergents and the controls. Thus, whether our study patients were truly allergic and, if so, what the allergenic material(s) in detergents might be, remains unknown. Therefore the reported incidence rate for detergent-induced allergy of 0.7% in dermatitic patients may be too high, possibly because of false-positive irritant reactions.","Allergic contact dermatitis to detergents: a multicenter study to assess prevalence Abs: <strong>BACKGROUND: </strong>Allergic contact dermatitis (ACD) to optical brighteners and enzymes in laundry detergents was the focus of numerous reports in the early 1970s. Subsequently, there has been little published on the incidence of allergic reactions to chemicals in laundry detergents. Nonetheless, consumers and physicians continue to ascribe allergic contact reactions to laundry detergents.<br /><br /><strong>OBJECTIVE: </strong>This article reports the findings of a multicenter study on the prevalence of patch test reactions to a liquid and a granular laundry detergent provided by Procter &amp; Gamble Company (Cincinnati, Ohio).<br /><br /><strong>METHODS: </strong>Patients referred to members of the North American Contact Dermatitis Group for evaluation of potential ACD were invited to participate in the study, which involved the placement of 2 patch tests (a 0.1% aqueous dilution of a granular laundry detergent and a 0.1% aqueous dilution of a liquid laundry detergent). Whether the patients had atopic dermatitis and whether they or their physicians felt that their dermatitis might be related to laundry detergents were noted. Reactions to the laundry detergents were correlated with allergic reactions to the following screening chemicals: fragrances, nickel, and potassium dichromate. Patients who experienced a reaction to at least one of the laundry detergents could enter phase II of the study, which involved testing to varying dilutions of the laundry detergents, to 0.1% sodium lauryl sulfate (as an irritant control), and to laundered patches of cotton. Patients positive in phase II could enter phase III, which involved wearing a garment laundered with the detergent. Phases II and III were double blinded.<br /><br /><strong>RESULTS: </strong>Of the 3120 patients seen by members of the North American Contact Dermatitis Group during the 2 years of this study, 738 patients volunteered to enroll. Enrollment was not statistically randomized. Of these 738, 5 (0.7%) had positive patch test reactions to granular laundry detergent (0.1%, aqueous); 3 of these 5 also had positive reactions to the liquid laundry detergent (0.1%, aqueous). In 4 of the 5 patients, the reaction to detergent was thought to have present relevance to their dermatitis; in 1 of the 5, the reaction was deemed to have past relevance. One of these 5 patients had allergy to fragrances. None of the patients was positive to nickel or chromate. Two of the 5 entered phases II and III. Of these 2 patients, 1 had essentially negative repeat dilutional patch testing and &quot;use testing&quot; suggesting that the earlier reaction patterns may have been irritant. The remaining patient had positive dilutional reactions to both the liquid and granular laundry detergent; however, she also had a positive reaction to sodium lauryl sulfate and to a swatch from a T-shirt laundered without detergent. Upon &quot;use testing&quot; in phase III, this latter patient experienced diffuse dermatitis under both the half of the T-shirt laundered with detergent and that laundered without detergent.<br /><br /><strong>CONCLUSION: </strong>Laundry detergents appear to be a rare cause of ACD. Among 738 patients with dermatitis, 5 (0.7%) reacted to a 0.1% aqueous dilution of a laundry detergent. Only 2 of these 5 patients could be evaluated in greater detail to differentiate allergic from irritant patch test reactions to detergents. Upon further testing in 2 patients, the reaction in 1 of 2 could not be reduplicated and the reaction in the other was invoked both by the detergents and the controls. Thus, whether our study patients were truly allergic and, if so, what the allergenic material(s) in detergents might be, remains unknown. Therefore the reported incidence rate for detergent-induced allergy of 0.7% in dermatitic patients may be too high, possibly because of false-positive irritant reactions."
1234428,Geetha et al. 2002,Anti-oxidant and immunomodulatory properties of seabuckthorn (Hippophae rhamnoides)--an in vitro study,"This study was designed to determine the anti-oxidant and immunomodulatory properties of seabuckthorn (Hippophae rhamnoides) using lymphocytes as a model system. Chromium(VI) as potassium dichromate was used to induce oxidative damage. The production of free radicals by chromium and the ability of alcoholic leaf and fruit extracts of seabuckthorn to inhibit the oxidative damage induced by chromium was investigated. Addition of chromium (10 microg/ml) to the cells resulted in enhanced cytotoxicity, apoptosis, free radical production and decreased glutathione (reduced) levels. Chromium also caused a significant inhibition of lymphocyte proliferation induced by both lipopolysaccharide and concanavalin A. Alcoholic extracts of leaves and fruits of seabuckthorn at a concentration of 500 microg/ml were found to inhibit chromium-induced free radical production, apoptosis, DNA fragmentation and restored the anti-oxidant status to that of control cells. In addition, these extracts also were able to arrest the chromium-induced inhibition of lymphocyte proliferation. These observations suggest that the alcoholic extracts of leaves and fruits of seabuckthorn have marked cytoprotective properties, which could be attributed to the anti-oxidant activity.","Anti-oxidant and immunomodulatory properties of seabuckthorn (Hippophae rhamnoides)--an in vitro study Abs: This study was designed to determine the anti-oxidant and immunomodulatory properties of seabuckthorn (Hippophae rhamnoides) using lymphocytes as a model system. Chromium(VI) as potassium dichromate was used to induce oxidative damage. The production of free radicals by chromium and the ability of alcoholic leaf and fruit extracts of seabuckthorn to inhibit the oxidative damage induced by chromium was investigated. Addition of chromium (10 microg/ml) to the cells resulted in enhanced cytotoxicity, apoptosis, free radical production and decreased glutathione (reduced) levels. Chromium also caused a significant inhibition of lymphocyte proliferation induced by both lipopolysaccharide and concanavalin A. Alcoholic extracts of leaves and fruits of seabuckthorn at a concentration of 500 microg/ml were found to inhibit chromium-induced free radical production, apoptosis, DNA fragmentation and restored the anti-oxidant status to that of control cells. In addition, these extracts also were able to arrest the chromium-induced inhibition of lymphocyte proliferation. These observations suggest that the alcoholic extracts of leaves and fruits of seabuckthorn have marked cytoprotective properties, which could be attributed to the anti-oxidant activity."
1234427,Hussain et al. 2002,Suitability of the European standard series of patch test allergens in Pakistani patients,,Suitability of the European standard series of patch test allergens in Pakistani patients Abs: 
1234426,Cleuvers et al. 2002,Combination effect of light and toxicity in algal tests,"The sensitivity of Scenedesmus subspicatus against potassium dichromate is positively correlated to the photon flux density during the algal growth inhibition test. Low photon flux densities led to significantly reduced maximum effects and higher EC50 levels. To improve the testing of colored substances, we distinguished between the toxic effect (chemical part, represented by potassium dichromate) and the shading effect (physical part, simulated by reduced light intensities during the test) of a hypothetical light absorbing substance. The contribution of these single effects to the total inhibition varied greatly. At high concentrations of potassium dichromate (1.6 and 3.2 mg L(-1)) the physical part never exceeded 25% of the total inhibition, not even at strongest light reduction, while at low concentrations (0.2 and 0.4 mg L(-1)) the physical effect became more prominent when halving the amount of available light. Further, the combination effect of the chemical and the physical effect could be calculated well only by using the concept of independent action. Thus, if chemical and physical effects are measured in combination, as is the case in tests with dye-stuffs, the current test protocol for the algal growth inhibition test may lead to incorrect estimations of the toxic potential.","Combination effect of light and toxicity in algal tests Abs: The sensitivity of Scenedesmus subspicatus against potassium dichromate is positively correlated to the photon flux density during the algal growth inhibition test. Low photon flux densities led to significantly reduced maximum effects and higher EC50 levels. To improve the testing of colored substances, we distinguished between the toxic effect (chemical part, represented by potassium dichromate) and the shading effect (physical part, simulated by reduced light intensities during the test) of a hypothetical light absorbing substance. The contribution of these single effects to the total inhibition varied greatly. At high concentrations of potassium dichromate (1.6 and 3.2 mg L(-1)) the physical part never exceeded 25% of the total inhibition, not even at strongest light reduction, while at low concentrations (0.2 and 0.4 mg L(-1)) the physical effect became more prominent when halving the amount of available light. Further, the combination effect of the chemical and the physical effect could be calculated well only by using the concept of independent action. Thus, if chemical and physical effects are measured in combination, as is the case in tests with dye-stuffs, the current test protocol for the algal growth inhibition test may lead to incorrect estimations of the toxic potential."
1234425,Selvakumar et al. 2002,Washing of new microscopic glass slides in dichromate solution does not influence sputum AFB smear results,"<strong>SETTING: </strong>Microscopy centres in Tiruvallur District, Tamil Nadu, India, implementing DOTS.<br /><br /><strong>OBJECTIVE: </strong>To know whether washing new glass slides in dichromate solution is essential for effective sputum acid-fast bacilli microscopy.<br /><br /><strong>METHODS: </strong>Two direct smears were prepared from each of 1750 sputum samples. One was made on dichromate solution-cleaned new glass slides and the other was made on unwashed new glass slides. The smears were blinded and examined.<br /><br /><strong>RESULTS: </strong>Of the 1750 specimens, 13.5% and 13.08% were positive for AFB using washed and unwashed slides, respectively (P = 0.12). The concordance between these two (including one grade above and one below) was 98.7%.<br /><br /><strong>CONCLUSION: </strong>Washing of new glass slides in dichromate solution is not essential for AFB microscopy.","Washing of new microscopic glass slides in dichromate solution does not influence sputum AFB smear results Abs: <strong>SETTING: </strong>Microscopy centres in Tiruvallur District, Tamil Nadu, India, implementing DOTS.<br /><br /><strong>OBJECTIVE: </strong>To know whether washing new glass slides in dichromate solution is essential for effective sputum acid-fast bacilli microscopy.<br /><br /><strong>METHODS: </strong>Two direct smears were prepared from each of 1750 sputum samples. One was made on dichromate solution-cleaned new glass slides and the other was made on unwashed new glass slides. The smears were blinded and examined.<br /><br /><strong>RESULTS: </strong>Of the 1750 specimens, 13.5% and 13.08% were positive for AFB using washed and unwashed slides, respectively (P = 0.12). The concordance between these two (including one grade above and one below) was 98.7%.<br /><br /><strong>CONCLUSION: </strong>Washing of new glass slides in dichromate solution is not essential for AFB microscopy."
1234424,Gowda et al. 2001,Spectrophotometric determination of certain vicinal dihydroxybenzene derivatives in pharmaceutical preparations,"A simple, rapid and sensitive spectrophotometric method for the assay of certain adrenergic drugs, [pyrocatechol (PC), levodopa (LD), methyldopa (MD) and dopamine (DP)] is described. The method involves the oxidation of o-dihydroxybenzene derivatives by K2CrO4 followed by oxidative coupling with sulfanilic acid (SPA), leading to the formation of a red or violet colored product having maximum absorbance at 490-495 nm for LD, MD and DP or at 560 nm for PC. This method has been successfully applied to the determination of LD, MD and DP in tablets and injections of pharmaceutical preparation. The common excipients do not interfere with the proposed method. A statistical comparison of these results with those of a reported method shows good agreement and indicates no significant difference in precision.","Spectrophotometric determination of certain vicinal dihydroxybenzene derivatives in pharmaceutical preparations Abs: A simple, rapid and sensitive spectrophotometric method for the assay of certain adrenergic drugs, [pyrocatechol (PC), levodopa (LD), methyldopa (MD) and dopamine (DP)] is described. The method involves the oxidation of o-dihydroxybenzene derivatives by K2CrO4 followed by oxidative coupling with sulfanilic acid (SPA), leading to the formation of a red or violet colored product having maximum absorbance at 490-495 nm for LD, MD and DP or at 560 nm for PC. This method has been successfully applied to the determination of LD, MD and DP in tablets and injections of pharmaceutical preparation. The common excipients do not interfere with the proposed method. A statistical comparison of these results with those of a reported method shows good agreement and indicates no significant difference in precision."
1234422,Fahmy et al. 2002,The protective role of thiola and soybean seeds against the genotoxicity induced by potassium dichromate in mice,"The genotoxic potential of potassium dichromate (K(2)Cr(2)O(7)) was evaluated in vivo in mice using different mutagenic end points. Chromosomal aberrations in bone-marrow and spermatocytes as well as sperm abnormalities in the tested mice were determined. The doses used were 3, 6, 12 mg K(2)Cr(2)O(7)kg(-1) body weight which correspond to 1/16, 1/8, 1/4 the experimental LD(50), respectively. The protective roles of i.p. injection with thiola (a synthetic sulfhydryl compound) at 20 mg kg(-1) body weight and feeding treatment with soybean seeds (30% of the diet) were also studied. For chromosomal aberration analysis, subacute treatment for a period of 3 weeks were performed. All the tested doses of K(2)Cr(2)O(7) induced a statistically significant increase in the percentage of chromosomal aberrations in both somatic and germ cells with dose and time relationships. The percentage of the induced chromosomal aberrations was significantly minimized in all groups of mice i.p. treated with thiola or fed soybean seeds during the period of treatment. Potassium dichromate also induced a significant increase (P&lt;0.01) in the percentage of abnormal sperms at the doses 6 and 12 mg kg(-1) body weight. Such percentage reached 7.52+/-0.45, 5.50+/-0.53 and 4.28+/-0.45 in mice treated with the highest tested dose of K(2)Cr(2)O(7), K(2)Cr(2)O(7) and thiola; K(2)Cr(2)O(7) and soybean, respectively compared with 2.14+/-0.33 for the control. In conclusion, the results demonstrate the genotoxic effect of potassium dichromate in mice. The results also confirm the protective role of thiola and soybean seeds against the genotoxicity of potassium dichromate.","The protective role of thiola and soybean seeds against the genotoxicity induced by potassium dichromate in mice Abs: The genotoxic potential of potassium dichromate (K(2)Cr(2)O(7)) was evaluated in vivo in mice using different mutagenic end points. Chromosomal aberrations in bone-marrow and spermatocytes as well as sperm abnormalities in the tested mice were determined. The doses used were 3, 6, 12 mg K(2)Cr(2)O(7)kg(-1) body weight which correspond to 1/16, 1/8, 1/4 the experimental LD(50), respectively. The protective roles of i.p. injection with thiola (a synthetic sulfhydryl compound) at 20 mg kg(-1) body weight and feeding treatment with soybean seeds (30% of the diet) were also studied. For chromosomal aberration analysis, subacute treatment for a period of 3 weeks were performed. All the tested doses of K(2)Cr(2)O(7) induced a statistically significant increase in the percentage of chromosomal aberrations in both somatic and germ cells with dose and time relationships. The percentage of the induced chromosomal aberrations was significantly minimized in all groups of mice i.p. treated with thiola or fed soybean seeds during the period of treatment. Potassium dichromate also induced a significant increase (P&lt;0.01) in the percentage of abnormal sperms at the doses 6 and 12 mg kg(-1) body weight. Such percentage reached 7.52+/-0.45, 5.50+/-0.53 and 4.28+/-0.45 in mice treated with the highest tested dose of K(2)Cr(2)O(7), K(2)Cr(2)O(7) and thiola; K(2)Cr(2)O(7) and soybean, respectively compared with 2.14+/-0.33 for the control. In conclusion, the results demonstrate the genotoxic effect of potassium dichromate in mice. The results also confirm the protective role of thiola and soybean seeds against the genotoxicity of potassium dichromate."
1234421,Dickel et al. 2002,"Surveillance scheme for occupational skin disease in the Saarland, FRG. First report from BKH-S","Occupational skin disease (OSD) is a significant public health concern. To keep OSDs under surveillance, a register of OSDs (BKH-S) was implemented in 1999 in the Saarland, FRG. We conducted a population-based register study to analyse all initial reports of OSDs reported to the BKH-S. 336 cases were prospectively assessed from July 1999 to June 2001. In 78% (n = 263) of the cases an occupational cause for the skin disease was stated, 91% (n = 240) of which fell within 16 occupational groups. This is equivalent to 6.8 cases per 10,000 workers per year within these occupational groups. Notably, young age groups (median age 35 years) were affected with a female predominance. The most frequent final diagnosis was irritant contact dermatitis (75%) followed by allergic contact dermatitis (34%) and atopic dermatitis (19%). The overall prevalence of occupationally relevant delayed-type reactors was 21% and of immediate-type reactors 17%. Work-related delayed-type sensitizations to potassium dichromate (n = 8) and immediate-type sensitizations to natural rubber latex (n = 11) were the most frequently observed. Questionnaire results showed frequent occupational skin contact with wet work (59%), detergents (48%), and disinfectants (38%). The second valid surveillance scheme for OSD in the FRG has been introduced and can be made available for further analysis.","Surveillance scheme for occupational skin disease in the Saarland, FRG. First report from BKH-S Abs: Occupational skin disease (OSD) is a significant public health concern. To keep OSDs under surveillance, a register of OSDs (BKH-S) was implemented in 1999 in the Saarland, FRG. We conducted a population-based register study to analyse all initial reports of OSDs reported to the BKH-S. 336 cases were prospectively assessed from July 1999 to June 2001. In 78% (n = 263) of the cases an occupational cause for the skin disease was stated, 91% (n = 240) of which fell within 16 occupational groups. This is equivalent to 6.8 cases per 10,000 workers per year within these occupational groups. Notably, young age groups (median age 35 years) were affected with a female predominance. The most frequent final diagnosis was irritant contact dermatitis (75%) followed by allergic contact dermatitis (34%) and atopic dermatitis (19%). The overall prevalence of occupationally relevant delayed-type reactors was 21% and of immediate-type reactors 17%. Work-related delayed-type sensitizations to potassium dichromate (n = 8) and immediate-type sensitizations to natural rubber latex (n = 11) were the most frequently observed. Questionnaire results showed frequent occupational skin contact with wet work (59%), detergents (48%), and disinfectants (38%). The second valid surveillance scheme for OSD in the FRG has been introduced and can be made available for further analysis."
1234420,Rahman and  Hoda 2002,Spectrophotometric method for the determination of nifedipine with 4-(methylamino)phenol and potassium dichromate,"A new simple, sensitive and reproducible spectrophotometric method for the determination of nifedipine in pure and dosage forms has been proposed. It is based on the reduction of nifedipine with Zn/NNH4Cl, followed by coupling with N-methyl-1,4-benzoquinoneimine--the oxidation product of 4-(methylamino)phenol, to give a chromophore which absorbed maximally at 525 nm. The experimental conditions were optimised and Beer's law was obeyed over the concentration range of 5-175 microg ml(-1). The molar absorptivity, detection limit, recovery and RSD were found to be 1.9 x 10(3) l mol(-1) cm(-1), 1.1 microg ml(-1), 99.7-100.5% and 0.3-0.8%, respectively. The proposed method was compared favourably with the official B.P. method.","Spectrophotometric method for the determination of nifedipine with 4-(methylamino)phenol and potassium dichromate Abs: A new simple, sensitive and reproducible spectrophotometric method for the determination of nifedipine in pure and dosage forms has been proposed. It is based on the reduction of nifedipine with Zn/NNH4Cl, followed by coupling with N-methyl-1,4-benzoquinoneimine--the oxidation product of 4-(methylamino)phenol, to give a chromophore which absorbed maximally at 525 nm. The experimental conditions were optimised and Beer's law was obeyed over the concentration range of 5-175 microg ml(-1). The molar absorptivity, detection limit, recovery and RSD were found to be 1.9 x 10(3) l mol(-1) cm(-1), 1.1 microg ml(-1), 99.7-100.5% and 0.3-0.8%, respectively. The proposed method was compared favourably with the official B.P. method."
1234418,Cleuvers and  Ratte 2002,The importance of light intensity in algal tests with coloured substances,"Current algal test protocols do not distinguish between chemical toxicity and growth inhibition due to physical shading when coloured substances like dyes are evaluated. To eliminate the interfering physical effect, we investigated the importance of light intensity and culture volume in the algal growth inhibition tests with Desmodesmus subspicatus and three selected dyestuffs. A photon flux density above light saturation is needed to prevent inhibition of algal growth solely due to the light absorption by dyes. Furthermore, a smaller culture volume and moderate shaking of the test flasks is advantageous in that these conditions decrease the influence of the light absorption. At 120 microE s(-1) m(-2), the shading effect of three tested dyes could be eliminated, up to a concentration of 100 mg l(-1). In a mixture with a blue dyestuff, the model toxicant potassium dichromate showed nearly the same EC50 as if applied alone, indicating that the impact of the dye was negligible. Also a small culture volume decreases the inhibition of the average growth rate of Desmodesmus. Thus, by increasing the light intensity and optionally also reducing the culture volume, this method allows a more direct measure of a potential inherent chemical toxicity of coloured substances to algae. Additionally, high light intensities and lower culture volumes result in lower coefficients of variation, which improves the sensitivity of the test for the statistical calculation of toxicity data.","The importance of light intensity in algal tests with coloured substances Abs: Current algal test protocols do not distinguish between chemical toxicity and growth inhibition due to physical shading when coloured substances like dyes are evaluated. To eliminate the interfering physical effect, we investigated the importance of light intensity and culture volume in the algal growth inhibition tests with Desmodesmus subspicatus and three selected dyestuffs. A photon flux density above light saturation is needed to prevent inhibition of algal growth solely due to the light absorption by dyes. Furthermore, a smaller culture volume and moderate shaking of the test flasks is advantageous in that these conditions decrease the influence of the light absorption. At 120 microE s(-1) m(-2), the shading effect of three tested dyes could be eliminated, up to a concentration of 100 mg l(-1). In a mixture with a blue dyestuff, the model toxicant potassium dichromate showed nearly the same EC50 as if applied alone, indicating that the impact of the dye was negligible. Also a small culture volume decreases the inhibition of the average growth rate of Desmodesmus. Thus, by increasing the light intensity and optionally also reducing the culture volume, this method allows a more direct measure of a potential inherent chemical toxicity of coloured substances to algae. Additionally, high light intensities and lower culture volumes result in lower coefficients of variation, which improves the sensitivity of the test for the statistical calculation of toxicity data."
1234417,Leonard et al. 2002,Generation of reactive oxygen species in the enzymatic reduction of PbCrO4 and related DNA damage,"Free radical reactions are believed to play an important role in the mechanism of Cr(VI)-induced carcinogenesis. Most studies concerning the role of free radical reactions have been limited to soluble Cr(VI). Various studies have shown that solubility is an important factor contributing to the carcinogenic potential of Cr(VI) compounds. Here, we report that reduction of insoluble PbCrO4 by glutathione reductase in the presence of NADPH as a cofactor generated hydroxyl radicals (.OH) and caused DNA damage. The .OH radicals were detected by electron spin resonance (ESR) using 5,5-dimethyl-N-oxide as a spin trap. Addition of catalase, a specific H2O2 scavenger, inhibited the .OH radical generation, indicating the involvement of H2O2 in the mechanism of Cr(VI)-induced .OH generation. Catalase reduced .OH radicals measured by electron spin resonance and reduced DNA strand breaks, indicating .OH radicals are involved in the damage measured. The H2O2 formation was measured by change in fluorescence of scopoletin in the presence of horseradish peroxidase. Molecular oxygen was used in the system as measured by oxygen consumption assay. Chelation of PbCrO4 impaired the generation of .OH radical. The results obtained from this study show that reduction of insoluble PbCrO4 by glutathione reductase/NADPH generates .OH radicals. The mechanism of .OH generation involves reduction of molecular oxygen to H2O2, which generates .OH radicals through a Fenton-like reaction. The .OH radicals generated by PbCrO4 caused DNA strand breakage.","Generation of reactive oxygen species in the enzymatic reduction of PbCrO4 and related DNA damage Abs: Free radical reactions are believed to play an important role in the mechanism of Cr(VI)-induced carcinogenesis. Most studies concerning the role of free radical reactions have been limited to soluble Cr(VI). Various studies have shown that solubility is an important factor contributing to the carcinogenic potential of Cr(VI) compounds. Here, we report that reduction of insoluble PbCrO4 by glutathione reductase in the presence of NADPH as a cofactor generated hydroxyl radicals (.OH) and caused DNA damage. The .OH radicals were detected by electron spin resonance (ESR) using 5,5-dimethyl-N-oxide as a spin trap. Addition of catalase, a specific H2O2 scavenger, inhibited the .OH radical generation, indicating the involvement of H2O2 in the mechanism of Cr(VI)-induced .OH generation. Catalase reduced .OH radicals measured by electron spin resonance and reduced DNA strand breaks, indicating .OH radicals are involved in the damage measured. The H2O2 formation was measured by change in fluorescence of scopoletin in the presence of horseradish peroxidase. Molecular oxygen was used in the system as measured by oxygen consumption assay. Chelation of PbCrO4 impaired the generation of .OH radical. The results obtained from this study show that reduction of insoluble PbCrO4 by glutathione reductase/NADPH generates .OH radicals. The mechanism of .OH generation involves reduction of molecular oxygen to H2O2, which generates .OH radicals through a Fenton-like reaction. The .OH radicals generated by PbCrO4 caused DNA strand breakage."
1234416,Duarte et al. 2002,Interference of the position of substances in an epicutaneous patch test battery with the occurrence of false-positive results,"<strong>BACKGROUND: </strong>Epicutaneous patch tests represent a practical and objective method that help in the etiologic diagnosis of allergic contact dermatitis. The technique of patch test application is an important factor in obtaining good results.<br /><br /><strong>OBJECTIVES: </strong>The aims of this study were (1) to determine whether the substances that form the test battery interfere with the patch test result and (2) to establish a rule for positioning the substances during patch test application.<br /><br /><strong>METHODS: </strong>Two hundred patients were studied. The standard patch test battery was applied in 3 versions. The original, with the substances applied in alphabetical order was called version 1 (V1) and tested on the left back in all patients In 100 patients, on the right side, the same substances were tested but applied at different positions, avoiding the proximity of elements with a tendency to cross reaction and/or cosensitizing. This version of the battery was named version 2 (V2). Another 100 patients had V1 applied to the left back, and, on the right side, the version 3 of the battery (V3) was applied, consisting of the same allergens but placed close to those with a tendency for cross reaction and/or cosensitization.<br /><br /><strong>RESULTS: </strong>In the group V1-V2, 163 results were positive in V1 and 124 in V2, with the difference being statistically significant (P &lt;.05). In the group V1-V3, 134 results were positive in V1 and 207 in V3, with the difference also being significant (P &lt;.005). The substances with the largest number of positive results, when tested close to other elements with a tendency for chemical affinity, were parabens, fragrance-mix, thimerosal, balsam of Peru, potassium dichromate, cobalt chloride, mercapto mix, and propylene glycol.<br /><br /><strong>CONCLUSIONS: </strong>(1) The substances of a patch test battery eliciting positive responses may interfere with test positivity to neighboring substances. (2) In addition to the already established techniques, the position of the substances forming the test battery needs to be determined; substances with a tendency to cross reaction or cosensitizing substances should be tested distant from one another, thus preventing the occurrence of false-positive results.","Interference of the position of substances in an epicutaneous patch test battery with the occurrence of false-positive results Abs: <strong>BACKGROUND: </strong>Epicutaneous patch tests represent a practical and objective method that help in the etiologic diagnosis of allergic contact dermatitis. The technique of patch test application is an important factor in obtaining good results.<br /><br /><strong>OBJECTIVES: </strong>The aims of this study were (1) to determine whether the substances that form the test battery interfere with the patch test result and (2) to establish a rule for positioning the substances during patch test application.<br /><br /><strong>METHODS: </strong>Two hundred patients were studied. The standard patch test battery was applied in 3 versions. The original, with the substances applied in alphabetical order was called version 1 (V1) and tested on the left back in all patients In 100 patients, on the right side, the same substances were tested but applied at different positions, avoiding the proximity of elements with a tendency to cross reaction and/or cosensitizing. This version of the battery was named version 2 (V2). Another 100 patients had V1 applied to the left back, and, on the right side, the version 3 of the battery (V3) was applied, consisting of the same allergens but placed close to those with a tendency for cross reaction and/or cosensitization.<br /><br /><strong>RESULTS: </strong>In the group V1-V2, 163 results were positive in V1 and 124 in V2, with the difference being statistically significant (P &lt;.05). In the group V1-V3, 134 results were positive in V1 and 207 in V3, with the difference also being significant (P &lt;.005). The substances with the largest number of positive results, when tested close to other elements with a tendency for chemical affinity, were parabens, fragrance-mix, thimerosal, balsam of Peru, potassium dichromate, cobalt chloride, mercapto mix, and propylene glycol.<br /><br /><strong>CONCLUSIONS: </strong>(1) The substances of a patch test battery eliciting positive responses may interfere with test positivity to neighboring substances. (2) In addition to the already established techniques, the position of the substances forming the test battery needs to be determined; substances with a tendency to cross reaction or cosensitizing substances should be tested distant from one another, thus preventing the occurrence of false-positive results."
1234415,White and  Jahnke 2002,Contrasting effects of UV-A and UV-B on photosynthesis and photoprotection of beta-carotene in two Dunaliella spp,"Photosynthetic and antioxidant responses following exposure to either ultraviolet-A or ultraviolet-B were contrasted in two species of the unicellular green alga, DUNALIELLA: Species selection was based on the ability of Dunaliella bardawil (UTEX 2538) to accumulate inter-thylakoid beta-carotene when subjected to environmental stress while Dunaliella salina (UTEX 200) lacks this ability. Cells were cultured in high and low levels of visible light (150 and 35 micro mol photons m(-2 )s(-1), respectively) and then either ultraviolet-A (320-400 nm) or ultraviolet-B (290-320 nm) was added to visible light for 24-h exposure. A potassium chromate solution was found to be an ideal screen for removal of ultraviolet-A and ultraviolet-C from ultraviolet-B radiation. There were no significant changes in photosynthetic or antioxidant parameters following exposure to ultraviolet-B. Ultraviolet-A exposure significantly decreased photosynthetic parameters (&gt;70% decrease in Fv/Fm and the ratio of light-limited to light-saturated photosynthesis in low beta-carotene cells) and resulted in 50% increases in ascorbate peroxidase activity and ascorbate concentrations. The results suggest exposure to ultraviolet-A (but not ultraviolet-B) directly affects photosynthesis, observed as a loss of photosystem II electron transport efficiency and increased radical formation. This research indicates that the accumulated beta-carotene in D. bardawil prevents UV-related photosynthetic damage through blue-light/ultraviolet-A absorption (supported by trends observed for antioxidant enzyme responses).","Contrasting effects of UV-A and UV-B on photosynthesis and photoprotection of beta-carotene in two Dunaliella spp Abs: Photosynthetic and antioxidant responses following exposure to either ultraviolet-A or ultraviolet-B were contrasted in two species of the unicellular green alga, DUNALIELLA: Species selection was based on the ability of Dunaliella bardawil (UTEX 2538) to accumulate inter-thylakoid beta-carotene when subjected to environmental stress while Dunaliella salina (UTEX 200) lacks this ability. Cells were cultured in high and low levels of visible light (150 and 35 micro mol photons m(-2 )s(-1), respectively) and then either ultraviolet-A (320-400 nm) or ultraviolet-B (290-320 nm) was added to visible light for 24-h exposure. A potassium chromate solution was found to be an ideal screen for removal of ultraviolet-A and ultraviolet-C from ultraviolet-B radiation. There were no significant changes in photosynthetic or antioxidant parameters following exposure to ultraviolet-B. Ultraviolet-A exposure significantly decreased photosynthetic parameters (&gt;70% decrease in Fv/Fm and the ratio of light-limited to light-saturated photosynthesis in low beta-carotene cells) and resulted in 50% increases in ascorbate peroxidase activity and ascorbate concentrations. The results suggest exposure to ultraviolet-A (but not ultraviolet-B) directly affects photosynthesis, observed as a loss of photosystem II electron transport efficiency and increased radical formation. This research indicates that the accumulated beta-carotene in D. bardawil prevents UV-related photosynthetic damage through blue-light/ultraviolet-A absorption (supported by trends observed for antioxidant enzyme responses)."
1234414,Livesley et al. 2002,Clinical examinations to validate self-completion questionnaires: dermatitis in the UK printing industry,"A self-completion questionnaire sent to 2600 Nottinghamshire members of the Graphical Paper and Media Union elicited a 62% response. Forty one per cent of respondents reported suffering a skin complaint at some time and 11% had a current skin problem on the hand. This paper reports the validation stage of the study. Samples of 45 'cases' of self-reported dermatitis and 60 'controls', who reported they had never suffered a skin complaint, were clinically examined. All 45 self-reported cases were clinically confirmed as dermatitis. Occupationally related irritant contact dermatitis (ICD) was diagnosed in 20 (44%); 26 (58%) complaints were thought to be induced or exacerbated by occupation. Of the controls, 21 (35%) were also diagnosed with a skin complaint, the majority being mild, with an occupational association in 17, the majority (15) being ICD. Sixteen ICD cases were patch tested resulting in positive reactions to colophony, neomycin, nickel and potassium dichromate (2 of each). Two cases of basal cell carcinoma on the face were also identified, of which the participants were unaware. Although there was no false positive self-reporting there was a considerable number of false negatives, demonstrating the importance of clinical validation of questionnaires relating to industrial skin disease. This study has highlighted the need for improvement in skin care provision in the printing industry.","Clinical examinations to validate self-completion questionnaires: dermatitis in the UK printing industry Abs: A self-completion questionnaire sent to 2600 Nottinghamshire members of the Graphical Paper and Media Union elicited a 62% response. Forty one per cent of respondents reported suffering a skin complaint at some time and 11% had a current skin problem on the hand. This paper reports the validation stage of the study. Samples of 45 'cases' of self-reported dermatitis and 60 'controls', who reported they had never suffered a skin complaint, were clinically examined. All 45 self-reported cases were clinically confirmed as dermatitis. Occupationally related irritant contact dermatitis (ICD) was diagnosed in 20 (44%); 26 (58%) complaints were thought to be induced or exacerbated by occupation. Of the controls, 21 (35%) were also diagnosed with a skin complaint, the majority being mild, with an occupational association in 17, the majority (15) being ICD. Sixteen ICD cases were patch tested resulting in positive reactions to colophony, neomycin, nickel and potassium dichromate (2 of each). Two cases of basal cell carcinoma on the face were also identified, of which the participants were unaware. Although there was no false positive self-reporting there was a considerable number of false negatives, demonstrating the importance of clinical validation of questionnaires relating to industrial skin disease. This study has highlighted the need for improvement in skin care provision in the printing industry."
1234412,Seoane et al. 2002,Malsegregation as a possible mechanism of aneuploidy induction by metal salts in MRC-5 human cells,"Many aneugenic compounds are known to affect one or more components of the mitotic apparatus leading to an erroneous migration of chromosomes. Malsegregation occurs when a chromosome (or a chromatid) fails to migrate and remains at the metaphase plate. Nondisjunction implies the lack of dissociation between sister chromatids and the migration of both together to the same pole. The aim of the present study was to provide evidence that the aneugenic effect of some metal salts is the consequence of malsegregation at anaphase and that it is not caused by nondisjunction mechanisms. The frequencies of lagging chromosomes at anaphase-telophase of mitosis, hypoploid metaphases, and kinetochore-positive micronuclei induced by cadmium chloride, potassium dichromate, and cacodilic acid (dimethylarsinic acid) in MRC-5 human cells were compared. The data indicate that all the tested compounds are able to induce aneuploidy in MRC-5 human cells. Positive, statistically significant correlations were found when kinetochore-positive micronuclei, hypoploidy, and lagging chromosome frequencies were compared. The results suggest that malsegregation is the main mechanism involved in the induction of aneuploidy by metal salts in MRC-5 cells.","Malsegregation as a possible mechanism of aneuploidy induction by metal salts in MRC-5 human cells Abs: Many aneugenic compounds are known to affect one or more components of the mitotic apparatus leading to an erroneous migration of chromosomes. Malsegregation occurs when a chromosome (or a chromatid) fails to migrate and remains at the metaphase plate. Nondisjunction implies the lack of dissociation between sister chromatids and the migration of both together to the same pole. The aim of the present study was to provide evidence that the aneugenic effect of some metal salts is the consequence of malsegregation at anaphase and that it is not caused by nondisjunction mechanisms. The frequencies of lagging chromosomes at anaphase-telophase of mitosis, hypoploid metaphases, and kinetochore-positive micronuclei induced by cadmium chloride, potassium dichromate, and cacodilic acid (dimethylarsinic acid) in MRC-5 human cells were compared. The data indicate that all the tested compounds are able to induce aneuploidy in MRC-5 human cells. Positive, statistically significant correlations were found when kinetochore-positive micronuclei, hypoploidy, and lagging chromosome frequencies were compared. The results suggest that malsegregation is the main mechanism involved in the induction of aneuploidy by metal salts in MRC-5 cells."
1234411,Sohrabpour et al. 2002,Gamma irradiator dose mapping simulation using the MCNP code and benchmarking with dosimetry,"The Monte Carlo transport code, MCNP, has been applied in simulating dose rate distribution in the IR-136 gamma irradiator system. Isodose curves, cumulative dose values, and system design data such as throughputs, over-dose-ratios, and efficiencies have been simulated as functions of product density. Simulated isodose curves, and cumulative dose values were compared with dosimetry values obtained using polymethyle-methacrylate, Fricke, ethanol-chlorobenzene, and potassium dichromate dosimeters. The produced system design data were also found to agree quite favorably with those of the system manufacturer's data. MCNP has thus been found to be an effective transport code for handling of various dose mapping excercises for gamma irradiators.","Gamma irradiator dose mapping simulation using the MCNP code and benchmarking with dosimetry Abs: The Monte Carlo transport code, MCNP, has been applied in simulating dose rate distribution in the IR-136 gamma irradiator system. Isodose curves, cumulative dose values, and system design data such as throughputs, over-dose-ratios, and efficiencies have been simulated as functions of product density. Simulated isodose curves, and cumulative dose values were compared with dosimetry values obtained using polymethyle-methacrylate, Fricke, ethanol-chlorobenzene, and potassium dichromate dosimeters. The produced system design data were also found to agree quite favorably with those of the system manufacturer's data. MCNP has thus been found to be an effective transport code for handling of various dose mapping excercises for gamma irradiators."
1234410,Dabeka et al. 2002,"Routine, high-sensitivity, cold vapor atomic absorption spectrometric determination of total mercury in foods after low-temperature digestion","A cold vapor atomic absorption spectrometric method was developed for the subnanogram-per-gram determination of total Hg in a wide variety of foods. Foods were weighed into 50 mL polypropylene centrifuge tubes and dried without charring at 55 degrees C in a circulating oven. Samples were then digested at 58 degrees C with HNO3, HCl, and H2O2. After matrix modification with solutions of 2% Mg(NO3)2, 0.01% Triton X-100, and Cu(II) at 10 microg/mL, samples were analyzed by using a CeTAC Technologies M-6000A dedicated Hg analyzer. Based on a 2 g sample weight, the detection limit of the method over 12 batches averaged 0.30 ng/g wet weight and ranged from 0.03 to 0.6 ng/g. Recoveries of Hg added to 17 different foods, analyzed in a routine manner, averaged 97%, and individual recoveries ranged from 77 to 107%. Accuracy was confirmed by analysis of 7 biological reference materials from the National Research Council of Canada and the National Institute of Standards and Technology. Stabilization of low concentrations of Hg in solutions containing no sample was required to prevent loss of Hg from blanks. In a comparison of NaCl, potassium dichromate, and Au(II), chloride was much more effective for stabilization than the other two, and HCl was used for subsequent stabilization.","Routine, high-sensitivity, cold vapor atomic absorption spectrometric determination of total mercury in foods after low-temperature digestion Abs: A cold vapor atomic absorption spectrometric method was developed for the subnanogram-per-gram determination of total Hg in a wide variety of foods. Foods were weighed into 50 mL polypropylene centrifuge tubes and dried without charring at 55 degrees C in a circulating oven. Samples were then digested at 58 degrees C with HNO3, HCl, and H2O2. After matrix modification with solutions of 2% Mg(NO3)2, 0.01% Triton X-100, and Cu(II) at 10 microg/mL, samples were analyzed by using a CeTAC Technologies M-6000A dedicated Hg analyzer. Based on a 2 g sample weight, the detection limit of the method over 12 batches averaged 0.30 ng/g wet weight and ranged from 0.03 to 0.6 ng/g. Recoveries of Hg added to 17 different foods, analyzed in a routine manner, averaged 97%, and individual recoveries ranged from 77 to 107%. Accuracy was confirmed by analysis of 7 biological reference materials from the National Research Council of Canada and the National Institute of Standards and Technology. Stabilization of low concentrations of Hg in solutions containing no sample was required to prevent loss of Hg from blanks. In a comparison of NaCl, potassium dichromate, and Au(II), chloride was much more effective for stabilization than the other two, and HCl was used for subsequent stabilization."
1234409,Klein et al. 2002,Chromate-induced epimutations in mammalian cells,"Epigenetic gene silencing by aberrant DNA methylation of gene promoter regions is a nonmutagenic but heritable epigenetic mechanism that may mistakenly cause the silencing of important cancer-related tumor suppressor genes. Using a transgenic, V79-derived, mammalian cell line (G12) that contains a bacterial gpt reporter gene in its DNA, we can study carcinogen-induced gene inactivation by mutagenic as well as epigenetic DNA methylation mechanisms. Whereas numerous carcinogens have previously been shown to be mutagenic in these cells, a few carcinogens, including nickel, diethylstilbestrol, and X-rays, are also capable of silencing the G12 cell gpt transgene by aberrant DNA methylation. Here we report for the first time that carcinogenic potassium chromate salts can also induce aberrant DNA methylation in this system. In contrast insoluble barium chromate produced significant level of mutations in these cells but did not cause DNA methylation changes associated with transgene expression.","Chromate-induced epimutations in mammalian cells Abs: Epigenetic gene silencing by aberrant DNA methylation of gene promoter regions is a nonmutagenic but heritable epigenetic mechanism that may mistakenly cause the silencing of important cancer-related tumor suppressor genes. Using a transgenic, V79-derived, mammalian cell line (G12) that contains a bacterial gpt reporter gene in its DNA, we can study carcinogen-induced gene inactivation by mutagenic as well as epigenetic DNA methylation mechanisms. Whereas numerous carcinogens have previously been shown to be mutagenic in these cells, a few carcinogens, including nickel, diethylstilbestrol, and X-rays, are also capable of silencing the G12 cell gpt transgene by aberrant DNA methylation. Here we report for the first time that carcinogenic potassium chromate salts can also induce aberrant DNA methylation in this system. In contrast insoluble barium chromate produced significant level of mutations in these cells but did not cause DNA methylation changes associated with transgene expression."
1234408,Krupa et al. 2002,Chromium incorporated in RNA and DNA,The objective of this study was to examine the effect of Cr(III) (chromium chloride) and Cr(VI) (potassium dichromate) on RNA and DNA-chromium adducts formation in isolated nucleic acids and isolated pig lymphocytes. The incubation of cells with potassium dichromate and chromium chloride at concentrations of 10 and 100 microM results in binding of a 1.2-1.9 fold greater number of chromium atoms to nuclear DNA than to total cellular RNA. The incubation of total cellular RNA and nuclear DNA isolated from lymphocytes with CrCl3 and K2Cr2O7 yielded a binding of 1.1-1.6 fold more of Cr atoms to RNA than to DNA. The number of chromium atoms bound to nucleic acids is higher after incubation with K2Cr2O7 than with CrCl3 in both experimental systems.,Chromium incorporated in RNA and DNA Abs: The objective of this study was to examine the effect of Cr(III) (chromium chloride) and Cr(VI) (potassium dichromate) on RNA and DNA-chromium adducts formation in isolated nucleic acids and isolated pig lymphocytes. The incubation of cells with potassium dichromate and chromium chloride at concentrations of 10 and 100 microM results in binding of a 1.2-1.9 fold greater number of chromium atoms to nuclear DNA than to total cellular RNA. The incubation of total cellular RNA and nuclear DNA isolated from lymphocytes with CrCl3 and K2Cr2O7 yielded a binding of 1.1-1.6 fold more of Cr atoms to RNA than to DNA. The number of chromium atoms bound to nucleic acids is higher after incubation with K2Cr2O7 than with CrCl3 in both experimental systems.
1234406,Thompson and  Belsito 2002,Regional variation in prevalence and etiology of allergic contact dermatitis,"<strong>BACKGROUND: </strong>The 1994-1996 North American Contact Dermatitis Group (NACDG) patch test results were the first, since the inception of the NACDG in 1970, to include results from a medium-sized metropolitan city in the Midwest.<br /><br /><strong>OBJECTIVE: </strong>The aim of this study was to determine whether the causative allergens of allergic contact dermatitis (ACD) in the Midwest differ from those in other regions of the United States and, if so, whether occupational or other factors account for the observed differences.<br /><br /><strong>METHODS: </strong>Retrospective analyses of patch test data collected at the University of Kansas Medical Center (Kansas City, KS) were compared with the data collected by the other NACDG centers.<br /><br /><strong>RESULTS: </strong>Patients in Kansas City were statistically more likely to react to potassium dichromate, formaldehyde and its releasers, methylchloroisothiazolinone/methylisothiazolinone (MCI/MI), and glutaraldehyde. Occupational exposures to chromium and formaldehyde were increased significantly among patients from Kansas City, although the percentages of the local population engaged in these occupations did not differ from those in other NACDG cities. Equal percentages of workers in Kansas City and nationally had occupationally related allergy to glutaraldehyde, although the overall rate of glutaraldehyde was higher among patients from Kansas City. Most cases of relevant allergy to MCI/MI were cosmetically induced both in Kansas City and nationally.<br /><br /><strong>CONCLUSIONS: </strong>The current findings show significant regional differences in causal allergens. The increased percentages of patients seen with ACD to formaldehyde, formaldehyde-releasing agents, and potassium dichromate in Kansas City were likely caused by the referral of greater numbers of work-related cases. However, occupationally acquired ACD to MCI/MI and glutaraldehyde were not more frequent in Kansas City than nationally, suggesting that other factors might be operative. Although awareness of national trends is important, dermatologists must be cognizant of regional variations in allergen sources within their communities and referral networks.","Regional variation in prevalence and etiology of allergic contact dermatitis Abs: <strong>BACKGROUND: </strong>The 1994-1996 North American Contact Dermatitis Group (NACDG) patch test results were the first, since the inception of the NACDG in 1970, to include results from a medium-sized metropolitan city in the Midwest.<br /><br /><strong>OBJECTIVE: </strong>The aim of this study was to determine whether the causative allergens of allergic contact dermatitis (ACD) in the Midwest differ from those in other regions of the United States and, if so, whether occupational or other factors account for the observed differences.<br /><br /><strong>METHODS: </strong>Retrospective analyses of patch test data collected at the University of Kansas Medical Center (Kansas City, KS) were compared with the data collected by the other NACDG centers.<br /><br /><strong>RESULTS: </strong>Patients in Kansas City were statistically more likely to react to potassium dichromate, formaldehyde and its releasers, methylchloroisothiazolinone/methylisothiazolinone (MCI/MI), and glutaraldehyde. Occupational exposures to chromium and formaldehyde were increased significantly among patients from Kansas City, although the percentages of the local population engaged in these occupations did not differ from those in other NACDG cities. Equal percentages of workers in Kansas City and nationally had occupationally related allergy to glutaraldehyde, although the overall rate of glutaraldehyde was higher among patients from Kansas City. Most cases of relevant allergy to MCI/MI were cosmetically induced both in Kansas City and nationally.<br /><br /><strong>CONCLUSIONS: </strong>The current findings show significant regional differences in causal allergens. The increased percentages of patients seen with ACD to formaldehyde, formaldehyde-releasing agents, and potassium dichromate in Kansas City were likely caused by the referral of greater numbers of work-related cases. However, occupationally acquired ACD to MCI/MI and glutaraldehyde were not more frequent in Kansas City than nationally, suggesting that other factors might be operative. Although awareness of national trends is important, dermatologists must be cognizant of regional variations in allergen sources within their communities and referral networks."
1234405,Li and  Wang 2002,Contact hypersensitivity in hand dermatitis,"Contact hypersensitivity (CHS) in hand dermatitis (HD) was studied by patch testing (PT) 105 consecutive adult HD patients and 361 cases of suspected non-hand allergic contact dermatitis (NHD). The suspected offending agents were also investigated by a questionnaire. Age and sex distribution was no different between the 2 groups. The total positivity rate of PT in the HD group was much lower than in the control group (46.7% versus 63.2%, p &lt; 0.01, chi2-test). The most common allergens in HD were rubber mix(17.1%), p-phenylenediamine (PPD) (14.3%), fragrance mix (9.5%), nickel (9.5%), colophonium (6.7%) and potassium dichromate (2.9%), while those in the control group, in sequence, were nickel (20.5%), rubber mix (16.9%), PPD (14.1%), fragrance mix (12.7%), potassium dichromate (5.5%) and colophonium (5.0%). The positivity rate to nickel was lower in the HD group (9.5% versus 20.5%, p &lt; 0.05, chi2-test), while there was no significant difference for the other allergens. HD was divided arbitrarily into 5 groups: (1) vesicular form, in which fine papules and vesicles can be detected. 65.7% of the HD was vesicular form and 55.1% of them were PT positive; (2) fissured form, in which dry skin with fine fissures or desquamation is seen. 8.6% of the HD was fissured form and 30% of them were PT positive; (3) hyperkeratotic form, in which the lesions are thick, hyperkeratotic plaques - 6.7% of the HD was this form and no positive reaction was found; (4) hand and foot dermatitis (HFD) - 12.4% of HD was HFD and 53.8% of them were PT positive; (5) pompholyx - 6.7% of the patients had pompholyx and one positive result to nickel was detected. The suspected offending agents were reported in only 13 (12.4%) patients. These results suggest that CHS is less common in HD than in NHD and that other factors, such as skin irritation, may play more of a role in HD. Nickel allergy is less common in HD than in NHD. CHS may play a role in more than 1/2 of vesicular form HD, HFD and in some fissured HD also, but is less common in hyperkeratotic HD and pompholyx. Only a small proportion of the HD patients could report the suspected offending agents and PT should be performed in all patients with chronic HD.","Contact hypersensitivity in hand dermatitis Abs: Contact hypersensitivity (CHS) in hand dermatitis (HD) was studied by patch testing (PT) 105 consecutive adult HD patients and 361 cases of suspected non-hand allergic contact dermatitis (NHD). The suspected offending agents were also investigated by a questionnaire. Age and sex distribution was no different between the 2 groups. The total positivity rate of PT in the HD group was much lower than in the control group (46.7% versus 63.2%, p &lt; 0.01, chi2-test). The most common allergens in HD were rubber mix(17.1%), p-phenylenediamine (PPD) (14.3%), fragrance mix (9.5%), nickel (9.5%), colophonium (6.7%) and potassium dichromate (2.9%), while those in the control group, in sequence, were nickel (20.5%), rubber mix (16.9%), PPD (14.1%), fragrance mix (12.7%), potassium dichromate (5.5%) and colophonium (5.0%). The positivity rate to nickel was lower in the HD group (9.5% versus 20.5%, p &lt; 0.05, chi2-test), while there was no significant difference for the other allergens. HD was divided arbitrarily into 5 groups: (1) vesicular form, in which fine papules and vesicles can be detected. 65.7% of the HD was vesicular form and 55.1% of them were PT positive; (2) fissured form, in which dry skin with fine fissures or desquamation is seen. 8.6% of the HD was fissured form and 30% of them were PT positive; (3) hyperkeratotic form, in which the lesions are thick, hyperkeratotic plaques - 6.7% of the HD was this form and no positive reaction was found; (4) hand and foot dermatitis (HFD) - 12.4% of HD was HFD and 53.8% of them were PT positive; (5) pompholyx - 6.7% of the patients had pompholyx and one positive result to nickel was detected. The suspected offending agents were reported in only 13 (12.4%) patients. These results suggest that CHS is less common in HD than in NHD and that other factors, such as skin irritation, may play more of a role in HD. Nickel allergy is less common in HD than in NHD. CHS may play a role in more than 1/2 of vesicular form HD, HFD and in some fissured HD also, but is less common in hyperkeratotic HD and pompholyx. Only a small proportion of the HD patients could report the suspected offending agents and PT should be performed in all patients with chronic HD."
1234404,Lozsekova et al. 2002,"The effect of nickel sulphate, potassium dichromate, cobalt nitrate and cadmium sulphate on the proteins of cellular contacts and actin skeleton of cultivated human keratinocytes","The authors tested the effects of known allergens, namely nickel sulphate, potassium dichromate, cobalt nitrate and cytotoxic cadmium sulphate on the proteins of cellular contacts (vinculin, talin, E-cadherin, desmoplaktin) and actin cytoskeleton (actin filaments) of cultivated human keratinocytes. The localisation of proteins of cellular contacts was detected by means of direct immunofluorescence. The authors have detected a decrease in, and destruction of cellular contact proteins and actin cytoskeleton after testing the effect of all allergens, while the most significant changes were detected in E-cadherin, vunkulin and actin filaments. Desmoplaktin and talin were less damaged. Potassium dichromate caused damage already in concentration of 1 microg/ml. A similar effect of the other two tested haptanes was brought about in concentration being 100-fold higher. CONCLUSION: the gained results indicate that the investigation of cellular contact proteins and actin cytoskeleton of cultivated human keratinocytes can possibly become a part of the testing of allergy-triggering potential of chemical substances. (Tab. 1, Fig. 4, Ref. 18.)","The effect of nickel sulphate, potassium dichromate, cobalt nitrate and cadmium sulphate on the proteins of cellular contacts and actin skeleton of cultivated human keratinocytes Abs: The authors tested the effects of known allergens, namely nickel sulphate, potassium dichromate, cobalt nitrate and cytotoxic cadmium sulphate on the proteins of cellular contacts (vinculin, talin, E-cadherin, desmoplaktin) and actin cytoskeleton (actin filaments) of cultivated human keratinocytes. The localisation of proteins of cellular contacts was detected by means of direct immunofluorescence. The authors have detected a decrease in, and destruction of cellular contact proteins and actin cytoskeleton after testing the effect of all allergens, while the most significant changes were detected in E-cadherin, vunkulin and actin filaments. Desmoplaktin and talin were less damaged. Potassium dichromate caused damage already in concentration of 1 microg/ml. A similar effect of the other two tested haptanes was brought about in concentration being 100-fold higher. CONCLUSION: the gained results indicate that the investigation of cellular contact proteins and actin cytoskeleton of cultivated human keratinocytes can possibly become a part of the testing of allergy-triggering potential of chemical substances. (Tab. 1, Fig. 4, Ref. 18.)"
1234403,Khurana et al. 2002,Patch testing in discoid eczema,"Fifty patients of both sexes with clinically suspected discoid eczema were patch tested with the Indian Standard Patch Test Battery approved by the Contact and Occupational Dermatosis Forum of India (CODFI). Most of these patients were young adults between 20 and 39 years old, with a mean age of 36 years. The mean duration of symptoms was 21/2 years. The occupational profiles of the patients included farmers (24%), housewives (18%), students (14%), housewives engaged in farming (12%), shopkeepers (10%), and laborers (8%). The miscellaneous group, including technicians, drivers, cable operators, office workers, and computer operators, accounted for the remaining 14%. The common clinical patterns of presentation of discoid eczema included hands and feet (44%), hands and forearms' (30%), legs and feet (12%) and trunk and limbs (12%). Patch test analysis of these patients revealed that, out of the 50 subjects tested, 28 (56%) reacted to one or more allergens. Potassium dichromate was the most common allergen (20%), followed by nickel (16%), cobalt chloride, and fragrance (12% each) in decreasing order of frequency. Hence, it may be concluded that patch testing should be considered for all patients with severe or persistent discoid eczema because allergic contact dermatitis may be relatively common in such patients and the avoidance of offending allergens may be of substantial benefit to the patients.","Patch testing in discoid eczema Abs: Fifty patients of both sexes with clinically suspected discoid eczema were patch tested with the Indian Standard Patch Test Battery approved by the Contact and Occupational Dermatosis Forum of India (CODFI). Most of these patients were young adults between 20 and 39 years old, with a mean age of 36 years. The mean duration of symptoms was 21/2 years. The occupational profiles of the patients included farmers (24%), housewives (18%), students (14%), housewives engaged in farming (12%), shopkeepers (10%), and laborers (8%). The miscellaneous group, including technicians, drivers, cable operators, office workers, and computer operators, accounted for the remaining 14%. The common clinical patterns of presentation of discoid eczema included hands and feet (44%), hands and forearms' (30%), legs and feet (12%) and trunk and limbs (12%). Patch test analysis of these patients revealed that, out of the 50 subjects tested, 28 (56%) reacted to one or more allergens. Potassium dichromate was the most common allergen (20%), followed by nickel (16%), cobalt chloride, and fragrance (12% each) in decreasing order of frequency. Hence, it may be concluded that patch testing should be considered for all patients with severe or persistent discoid eczema because allergic contact dermatitis may be relatively common in such patients and the avoidance of offending allergens may be of substantial benefit to the patients."
1234401,Ferslew et al. 2003,Determination of chromate adulteration of human urine by automated colorimetric and capillary ion electrophoretic analyses,"Various chemicals can be added to urine specimens collected for drug analysis to abnormally elevate ionic concentrations and/or interfere with either immunoassay urine drug-screening procedures or gas chromatographic-mass spectrometric confirmation techniques. One such adulterant, &quot;Urine Luck&quot; (formula 5.3), has been identified in our previous research to contain potassium dichromate. Screening of suspected adulterated specimens and confirmation of the adulterant are important for forensic drug screening. The application and comparison of automated colorimetric and capillary ion electrophoretic techniques for the detection, confirmation, and quantitation of chromate adulteration of urine specimens were the purpose of this investigation. Thirty-six urine specimens suspected of adulteration were analyzed for chromate by colorimetric analysis with diphenylcarbazide. Duplicate aliquots were analyzed for chromate by capillary ion electrophoresis. Results of the colorimetric chromate analyses revealed a mean chromate concentration of 929 microg/mL with a standard error of 177 microg/mL and a range of 30 to 5634 microg/mL. Results of the capillary ion electrophoresis chromate analyses revealed a mean chromate concentration of 1009 microg/mL with a standard error of 218 microg/mL and a range of 20 to 7501 microg/mL. The correlation coefficient between the capillary ion electrophoretic and colorimetric chromate results was r = 0.9669. Application of the automated diphenylcarbazide colorimetric technique provides rapid determination of chromate adulteration of a urine specimen. Capillary ion electrophoresis offers a separation technique to confirm the presence of chromate in suspected adulterated specimens. The excellent correlation between these methods substantiates their application to forensic testing as screening and/or confirmation techniques.","Determination of chromate adulteration of human urine by automated colorimetric and capillary ion electrophoretic analyses Abs: Various chemicals can be added to urine specimens collected for drug analysis to abnormally elevate ionic concentrations and/or interfere with either immunoassay urine drug-screening procedures or gas chromatographic-mass spectrometric confirmation techniques. One such adulterant, &quot;Urine Luck&quot; (formula 5.3), has been identified in our previous research to contain potassium dichromate. Screening of suspected adulterated specimens and confirmation of the adulterant are important for forensic drug screening. The application and comparison of automated colorimetric and capillary ion electrophoretic techniques for the detection, confirmation, and quantitation of chromate adulteration of urine specimens were the purpose of this investigation. Thirty-six urine specimens suspected of adulteration were analyzed for chromate by colorimetric analysis with diphenylcarbazide. Duplicate aliquots were analyzed for chromate by capillary ion electrophoresis. Results of the colorimetric chromate analyses revealed a mean chromate concentration of 929 microg/mL with a standard error of 177 microg/mL and a range of 30 to 5634 microg/mL. Results of the capillary ion electrophoresis chromate analyses revealed a mean chromate concentration of 1009 microg/mL with a standard error of 218 microg/mL and a range of 20 to 7501 microg/mL. The correlation coefficient between the capillary ion electrophoretic and colorimetric chromate results was r = 0.9669. Application of the automated diphenylcarbazide colorimetric technique provides rapid determination of chromate adulteration of a urine specimen. Capillary ion electrophoresis offers a separation technique to confirm the presence of chromate in suspected adulterated specimens. The excellent correlation between these methods substantiates their application to forensic testing as screening and/or confirmation techniques."
1234400,Rudolf and  Cervinka 2002,Time dependent appearance of selected apoptotic markers and usefulness of their detection in vitro,"Many experiments have demonstrated that some cell lines are resistant to chemically induced apoptosis in vitro, and that apoptosis itself is far from being a homogenous phenomenon. Here we show that 10 microg/ml etoposide elicited only minor changes in Bowes human melanoma cells (temporary decrease in cell viability and proliferation, transient phospatidylserine externalization and caspase-3 activation), which weren't clearly capable to start apoptotic pathway in the entire treated population. On the other hand, potassium chromate at concentration of 150 microg/ml executed cell death bearing some features of apoptosis (cell blebbing, caspase-3 activation and cytoskeletal changes) but lacking or showing weakly others (DNA fragmentation and phospatidylserine externalization). Our results suggest that in detecting apoptosis several fault-proof detection systems are to be used to avoid misleading results and conclusions in each experimental setting.","Time dependent appearance of selected apoptotic markers and usefulness of their detection in vitro Abs: Many experiments have demonstrated that some cell lines are resistant to chemically induced apoptosis in vitro, and that apoptosis itself is far from being a homogenous phenomenon. Here we show that 10 microg/ml etoposide elicited only minor changes in Bowes human melanoma cells (temporary decrease in cell viability and proliferation, transient phospatidylserine externalization and caspase-3 activation), which weren't clearly capable to start apoptotic pathway in the entire treated population. On the other hand, potassium chromate at concentration of 150 microg/ml executed cell death bearing some features of apoptosis (cell blebbing, caspase-3 activation and cytoskeletal changes) but lacking or showing weakly others (DNA fragmentation and phospatidylserine externalization). Our results suggest that in detecting apoptosis several fault-proof detection systems are to be used to avoid misleading results and conclusions in each experimental setting."
1234399,Gonzalo et al. 2003,Fossomatic cell-counting on ewe milk: comparison with direct microscopy and study of variation factors,"Using the Fossomatic method (FSCC) a total of 23,003 analytical SCC observations were carried out on 6400 aliquots taken from 80 individual ewe milk samples with the objective of studying the influence of 4 preservation procedures (without preservation, potassium dichromate, azidiol, and bronopol), 2 storage temperatures (ambient and refrigeration), 10 milk ages (3,6,12, and 24h, and 2,3,4,5,7, and 9d postcollection), and two analytical temperatures (40 and 60 degrees C). In addition, each sample was analyzed with direct microscopic method (DMSCC), using 3 different stainings for each sample: methylene blue (MB), May-Grünwald-Giemsa (MGG) and Pyronin Y-methyl green (PGM). This allowed DMSCC and FSCC (at 24 h of age) to be compared. The reference DMSCC from MB staining was a reliable method in ewe milk, though more specific stainings such as MGG and PMG slightly improve the residual standard deviation for repeated SCC. Between DMSCC and FSCC, the highest coefficients of correlation (0.972 to 0.996) corresponded to preserved and refrigerated milk, and the lowest (0.708 to 0.919) to unpreserved and ambient stored aliquots. Except for the unpreserved and ambient stored aliquots, SCC values were similar in all aliquots. Under FSCC, preservation, storage and analytical temperature, milk age, and most of the interactions showed a significant effect on SCC variation. In preserved samples, logSCC values ranged between 5.67 (bronopol) and 5.62 (azidiol). The higest values (5.72) were for unpreserved milk, which showed false overestimation of SCC due to bacterial proliferation. LogSCC was higher at 60 degrees C (5.68) than at 40 degrees C (5.65). The interaction between age, preservation and storage temperature showed no cell degeneration in properly handled samples over the 9 d of study.","Fossomatic cell-counting on ewe milk: comparison with direct microscopy and study of variation factors Abs: Using the Fossomatic method (FSCC) a total of 23,003 analytical SCC observations were carried out on 6400 aliquots taken from 80 individual ewe milk samples with the objective of studying the influence of 4 preservation procedures (without preservation, potassium dichromate, azidiol, and bronopol), 2 storage temperatures (ambient and refrigeration), 10 milk ages (3,6,12, and 24h, and 2,3,4,5,7, and 9d postcollection), and two analytical temperatures (40 and 60 degrees C). In addition, each sample was analyzed with direct microscopic method (DMSCC), using 3 different stainings for each sample: methylene blue (MB), May-Grünwald-Giemsa (MGG) and Pyronin Y-methyl green (PGM). This allowed DMSCC and FSCC (at 24 h of age) to be compared. The reference DMSCC from MB staining was a reliable method in ewe milk, though more specific stainings such as MGG and PMG slightly improve the residual standard deviation for repeated SCC. Between DMSCC and FSCC, the highest coefficients of correlation (0.972 to 0.996) corresponded to preserved and refrigerated milk, and the lowest (0.708 to 0.919) to unpreserved and ambient stored aliquots. Except for the unpreserved and ambient stored aliquots, SCC values were similar in all aliquots. Under FSCC, preservation, storage and analytical temperature, milk age, and most of the interactions showed a significant effect on SCC variation. In preserved samples, logSCC values ranged between 5.67 (bronopol) and 5.62 (azidiol). The higest values (5.72) were for unpreserved milk, which showed false overestimation of SCC due to bacterial proliferation. LogSCC was higher at 60 degrees C (5.68) than at 40 degrees C (5.65). The interaction between age, preservation and storage temperature showed no cell degeneration in properly handled samples over the 9 d of study."
1234398,Faherty et al. 2003,A Golgi-Cox morphological analysis of neuronal changes induced by environmental enrichment,"Exposure to an enriched environment (EE), consisting of a combination of increased exercise, social interactions and learning, has been shown to produce many positive effects in the CNS. In this study, we use a Golgi-Cox analysis to examine and dissect the role of various components of the enriched environment on two measures of neuronal growth: total cell volume and total dendritic length in four regions of the brain. In the hippocampus, CA1 and dentate gyrus cells, animals raised in an enriched environment demonstrate significant morphological change. These changes were not observed in layer V pyramidal neurons of the cerebral cortex or spiny neurons located in the striatum. To determine if one or more of the individual components of the EE were responsible for the changes in neuronal morphology, we examined mice raised with free access to exercise wheels. In these mice, no morphological changes were observed. These results suggest that changes in the CA1 and dentate gyrus morphology were a result of alterations in the animal's environment and not an increase in motor activity.","A Golgi-Cox morphological analysis of neuronal changes induced by environmental enrichment Abs: Exposure to an enriched environment (EE), consisting of a combination of increased exercise, social interactions and learning, has been shown to produce many positive effects in the CNS. In this study, we use a Golgi-Cox analysis to examine and dissect the role of various components of the enriched environment on two measures of neuronal growth: total cell volume and total dendritic length in four regions of the brain. In the hippocampus, CA1 and dentate gyrus cells, animals raised in an enriched environment demonstrate significant morphological change. These changes were not observed in layer V pyramidal neurons of the cerebral cortex or spiny neurons located in the striatum. To determine if one or more of the individual components of the EE were responsible for the changes in neuronal morphology, we examined mice raised with free access to exercise wheels. In these mice, no morphological changes were observed. These results suggest that changes in the CA1 and dentate gyrus morphology were a result of alterations in the animal's environment and not an increase in motor activity."
1234397,Balcerczyk et al. 2003,MRP1-transfected cells do not show increased resistance against oxidative stress,"Sensitivity of V79 Chinese hamster cells and V79 cells transfected with human MRP1 gene to several agents inducing oxidative stress was compared. Cells overexpressing MRP1 did not show increased resistance to tert-butyl hydroperoxide, diamide, paraquat, menadione, dichromate and carmustine as estimated by cell survival and DNA damage assessed by comet assay. These findings suggest that overexpression of MRP1 does not confer increased resistance to oxidative stress.","MRP1-transfected cells do not show increased resistance against oxidative stress Abs: Sensitivity of V79 Chinese hamster cells and V79 cells transfected with human MRP1 gene to several agents inducing oxidative stress was compared. Cells overexpressing MRP1 did not show increased resistance to tert-butyl hydroperoxide, diamide, paraquat, menadione, dichromate and carmustine as estimated by cell survival and DNA damage assessed by comet assay. These findings suggest that overexpression of MRP1 does not confer increased resistance to oxidative stress."
1234395,Ug and  Ceylan 2003,"Occurrence of resistance to antibiotics, metals, and plasmids in clinical strains of Staphylococcus spp","<strong>BACKGROUND: </strong>Presence of staphylococci resistant to antibiotics is of concern, as is the possible spread of resistance determinants among Staphylococcus species. During the past several years, a series of staphylococcal isolates that demonstrated reduced susceptibility to vancomycin or other glycopeptides has been reported. However, there are no useful data on species sensitivity of coagulase-negative staphylococci to heavy metals.<br /><br /><strong>METHODS: </strong>A total of 22 Staphylococcus spp. isolates recovered from clinical sources was studied for antibiotic and heavy metal resistance patterns and plasmid profiles. Isolated strains were biochemically identified by conventional tests followed by use of API Staph system. Isolates were tested for antimicrobial susceptibility by standard methods. Resistance patterns to nickel chloride (NiCl(2)), zinc sulfate (ZnSO(4)), lead acetate Pb(CH(3)COO)(2), cobalt chloride (CoCl(2)), copper sulfate (CuSO(4)), potassium chromate (K(2)Cr(2)O(7)), silver nitrate (AgNO(3)), and mercuric chloride (HgCl(2)) were surveyed by agar-dilution method. Plasmid DNA was prepared according to a previously described modification of alkaline lysis procedure.<br /><br /><strong>RESULTS: </strong>In this study, isolated strains included eight (36.4%) Staphylococcus xylosus, five (22.7%) Staphylococcus aureus, four (18.2%) nonidentifiable Staphylococcus spp., one (4.5%) Staphylococcus capitis, one (4.5%) Staphylococcus lentus, one (4.5%) Staphylococcus epidermidis, one (4.5%) Staphylococcus sciuri, and one (4.5%) Staphylococcus chromogenes. All strains showed widest resistance profile to both antibiotics and metals. Methicillin resistance of Staphylococcus aureus (MRSA) was 40%. Resistance to oxacillin was 53% in coagulase-negative staphylococci (CNS) strains. No isolate was resistant to vancomycin. All isolates were resistant to K(2)Cr(2)O(7) and Pb(CH(3)COO)(2); on the other hand, all isolates were sensitive to AgNO(3). Highest incidence of metal-antibiotic multiple resistance existed between K(2)Cr(2)O(7), Pb(CH(3)COO)(2), and penicillin-G. Plasmid content and profile studies showed that isolates carried plasmids ranging from 2.224 to 20.650 kb in size.<br /><br /><strong>CONCLUSIONS: </strong>Fifty percent of studied strains harbored plasmids and association between occurence of plasmids and resistance to antibiotics and heavy metals was observed.","Occurrence of resistance to antibiotics, metals, and plasmids in clinical strains of Staphylococcus spp Abs: <strong>BACKGROUND: </strong>Presence of staphylococci resistant to antibiotics is of concern, as is the possible spread of resistance determinants among Staphylococcus species. During the past several years, a series of staphylococcal isolates that demonstrated reduced susceptibility to vancomycin or other glycopeptides has been reported. However, there are no useful data on species sensitivity of coagulase-negative staphylococci to heavy metals.<br /><br /><strong>METHODS: </strong>A total of 22 Staphylococcus spp. isolates recovered from clinical sources was studied for antibiotic and heavy metal resistance patterns and plasmid profiles. Isolated strains were biochemically identified by conventional tests followed by use of API Staph system. Isolates were tested for antimicrobial susceptibility by standard methods. Resistance patterns to nickel chloride (NiCl(2)), zinc sulfate (ZnSO(4)), lead acetate Pb(CH(3)COO)(2), cobalt chloride (CoCl(2)), copper sulfate (CuSO(4)), potassium chromate (K(2)Cr(2)O(7)), silver nitrate (AgNO(3)), and mercuric chloride (HgCl(2)) were surveyed by agar-dilution method. Plasmid DNA was prepared according to a previously described modification of alkaline lysis procedure.<br /><br /><strong>RESULTS: </strong>In this study, isolated strains included eight (36.4%) Staphylococcus xylosus, five (22.7%) Staphylococcus aureus, four (18.2%) nonidentifiable Staphylococcus spp., one (4.5%) Staphylococcus capitis, one (4.5%) Staphylococcus lentus, one (4.5%) Staphylococcus epidermidis, one (4.5%) Staphylococcus sciuri, and one (4.5%) Staphylococcus chromogenes. All strains showed widest resistance profile to both antibiotics and metals. Methicillin resistance of Staphylococcus aureus (MRSA) was 40%. Resistance to oxacillin was 53% in coagulase-negative staphylococci (CNS) strains. No isolate was resistant to vancomycin. All isolates were resistant to K(2)Cr(2)O(7) and Pb(CH(3)COO)(2); on the other hand, all isolates were sensitive to AgNO(3). Highest incidence of metal-antibiotic multiple resistance existed between K(2)Cr(2)O(7), Pb(CH(3)COO)(2), and penicillin-G. Plasmid content and profile studies showed that isolates carried plasmids ranging from 2.224 to 20.650 kb in size.<br /><br /><strong>CONCLUSIONS: </strong>Fifty percent of studied strains harbored plasmids and association between occurence of plasmids and resistance to antibiotics and heavy metals was observed."
1234394,Cleuvers and  Weyers 2003,Algal growth inhibition test: does shading of coloured substances really matter?,"Coloured substances are often assumed to behave differently in the algal growth inhibition test due to shading of the algae. We have investigated EU-notifications of new substances and found no significant differences in algal test results between colours and non-colours. A modified method to differentiate between shading and toxicity is not satisfactory, because the method used to determine the shading effect is incorrect. Due to the shaking of the test flasks in the algal test intermittent light conditions are achieved which lead to a higher growth rate than expected from proposed tests with constant reduced light conditions. This will result in overestimation of the shading effect and thus to underestimation of chemical toxicity. Furthermore, we showed in experiments with the reference substance potassium dichromate that reduced light can reduce the measurable toxicity of chemicals. Comparing our results with approaches proposed in the literature, a simple approach to reduce effects of undesired shading when testing coloured substances is to achieve light saturation for the algae by increasing illumination at least to the upper limit given in test guidelines (120 microEs(-1)m(-2)) and, optionally, to reduce the light path by choosing smaller test volumes.","Algal growth inhibition test: does shading of coloured substances really matter? Abs: Coloured substances are often assumed to behave differently in the algal growth inhibition test due to shading of the algae. We have investigated EU-notifications of new substances and found no significant differences in algal test results between colours and non-colours. A modified method to differentiate between shading and toxicity is not satisfactory, because the method used to determine the shading effect is incorrect. Due to the shaking of the test flasks in the algal test intermittent light conditions are achieved which lead to a higher growth rate than expected from proposed tests with constant reduced light conditions. This will result in overestimation of the shading effect and thus to underestimation of chemical toxicity. Furthermore, we showed in experiments with the reference substance potassium dichromate that reduced light can reduce the measurable toxicity of chemicals. Comparing our results with approaches proposed in the literature, a simple approach to reduce effects of undesired shading when testing coloured substances is to achieve light saturation for the algae by increasing illumination at least to the upper limit given in test guidelines (120 microEs(-1)m(-2)) and, optionally, to reduce the light path by choosing smaller test volumes."
1234393,Barrera et al. 2003,HO-1 induction attenuates renal damage and oxidative stress induced by K2Cr2O7,"Heme oxygenase (HO) is the rate-limiting enzyme in the degradation of heme; its inducible isozyme HO-1 protects against some types of acute tissue injury. The expression and functional role of HO-1 in rats with renal injury induced by potassium dichromate (K(2)Cr(2)O(7)) was investigated in this work. Rats were studied 24 h after a single injection of K(2)Cr(2)O(7). To address the possible protective effect of HO-1 in this experimental model, this enzyme was induced by an injection of stannous chloride (SnCl(2)) 12 h before K(2)Cr(2)O(7) administration. The functional role of HO-1 in K(2)Cr(2)O(7) + SnCl(2)-treated animals was tested by inhibiting HO activity with an injection of zinc (II) protoporphyrin IX (ZnPP) 18 h before K(2)Cr(2)O(7). In K(2)Cr(2)O(7)-treated rats: (i) renal HO-1 content, measured by Western blot, increased 2.6-fold; and, (ii) renal nitrotyrosine and protein carbonyl content, markers of oxidative stress, increased 3.5- and 1.36-fold, respectively. Renal damage and oxidative stress were ameliorated and HO-1 content was increased in the K(2)Cr(2)O(7) + SnCl(2) group. The attenuation of renal injury and oxidative stress was lost by the inhibition of HO activity in K(2)Cr(2)O(7) + SnCl(2) + ZnPP-treated animals. Our data suggest that HO-1 overexpression induced by SnCl(2) is responsible for the attenuation of renal damage and oxidative stress induced by K(2)Cr(2)O(7).","HO-1 induction attenuates renal damage and oxidative stress induced by K2Cr2O7 Abs: Heme oxygenase (HO) is the rate-limiting enzyme in the degradation of heme; its inducible isozyme HO-1 protects against some types of acute tissue injury. The expression and functional role of HO-1 in rats with renal injury induced by potassium dichromate (K(2)Cr(2)O(7)) was investigated in this work. Rats were studied 24 h after a single injection of K(2)Cr(2)O(7). To address the possible protective effect of HO-1 in this experimental model, this enzyme was induced by an injection of stannous chloride (SnCl(2)) 12 h before K(2)Cr(2)O(7) administration. The functional role of HO-1 in K(2)Cr(2)O(7) + SnCl(2)-treated animals was tested by inhibiting HO activity with an injection of zinc (II) protoporphyrin IX (ZnPP) 18 h before K(2)Cr(2)O(7). In K(2)Cr(2)O(7)-treated rats: (i) renal HO-1 content, measured by Western blot, increased 2.6-fold; and, (ii) renal nitrotyrosine and protein carbonyl content, markers of oxidative stress, increased 3.5- and 1.36-fold, respectively. Renal damage and oxidative stress were ameliorated and HO-1 content was increased in the K(2)Cr(2)O(7) + SnCl(2) group. The attenuation of renal injury and oxidative stress was lost by the inhibition of HO activity in K(2)Cr(2)O(7) + SnCl(2) + ZnPP-treated animals. Our data suggest that HO-1 overexpression induced by SnCl(2) is responsible for the attenuation of renal damage and oxidative stress induced by K(2)Cr(2)O(7)."
1234392,Raspor et al. 2003,The involvement of ATP sulfurylase in Se(VI) and Cr(VI) reduction processes in the fission yeast Schizosaccharomyces pombe,The response of Schizosaccharomyces pombe towards the oxyanions selenate [Se(VI)] and dichromate [Cr(VI)] was investigated in order to establish the involvement of the yeast ATP sulfurylase in their reduction. An ATP sulfurylase-defective/selenate-resistant mutant of S. pombe (B-579 Se(R) -2) and an ATP sulfurylase-active/selenate-sensitive strain of S. pombe (B-579 Se(S)) were included in this study. The inhibitory effect of Se(VI) and Cr(VI) oxyanions on growth and bioaccumulation was measured. The sensitive strain showed natural sensitivity to selenate while the resistant mutant tolerated a 100-fold higher concentration of selenate. These results indicate that selenate toxicity to microorganisms is connected with the reduction of selenate to selenite. Both strains showed similar sensitivity to Cr(VI) and in this study there was no evidence that ATP sulfurylase participates in the reduction process of Cr(VI).,The involvement of ATP sulfurylase in Se(VI) and Cr(VI) reduction processes in the fission yeast Schizosaccharomyces pombe Abs: The response of Schizosaccharomyces pombe towards the oxyanions selenate [Se(VI)] and dichromate [Cr(VI)] was investigated in order to establish the involvement of the yeast ATP sulfurylase in their reduction. An ATP sulfurylase-defective/selenate-resistant mutant of S. pombe (B-579 Se(R) -2) and an ATP sulfurylase-active/selenate-sensitive strain of S. pombe (B-579 Se(S)) were included in this study. The inhibitory effect of Se(VI) and Cr(VI) oxyanions on growth and bioaccumulation was measured. The sensitive strain showed natural sensitivity to selenate while the resistant mutant tolerated a 100-fold higher concentration of selenate. These results indicate that selenate toxicity to microorganisms is connected with the reduction of selenate to selenite. Both strains showed similar sensitivity to Cr(VI) and in this study there was no evidence that ATP sulfurylase participates in the reduction process of Cr(VI).
1234390,Trattner et al. 2003,Use of in vitro release of interferon-gamma in the diagnosis of contact allergy to potassium dichromate - a controlled study,"The use of in vitro release of interferon-gamma (IFN-gamma) in the diagnosis of contact allergy to potassium dichromate was studied in 20 patients who had positive patch tests to chromate and in 30 control subjects (10 patients with contact dermatitis, allergic to other allergens, 10 patients with other dermatologic diseases and 10 healthy subjects). The release of IFN-gamma in the supernatants of the peripheral blood lymphocytes was significantly higher in the patients with proven allergy to chromate (P = 0.001). Further studies are needed to determine if IFN-gamma release may serve as an additional diagnostic tool in contact dermatitis.","Use of in vitro release of interferon-gamma in the diagnosis of contact allergy to potassium dichromate - a controlled study Abs: The use of in vitro release of interferon-gamma (IFN-gamma) in the diagnosis of contact allergy to potassium dichromate was studied in 20 patients who had positive patch tests to chromate and in 30 control subjects (10 patients with contact dermatitis, allergic to other allergens, 10 patients with other dermatologic diseases and 10 healthy subjects). The release of IFN-gamma in the supernatants of the peripheral blood lymphocytes was significantly higher in the patients with proven allergy to chromate (P = 0.001). Further studies are needed to determine if IFN-gamma release may serve as an additional diagnostic tool in contact dermatitis."
1234388,Labra et al. 2003,AFLP analysis as biomarker of exposure to organic and inorganic genotoxic substances in plants,"In recent years several plant species have been in use as bioindicators and several tests have been developed to evaluate the toxicity of environmental pollutants in vegetal organisms. In the present paper Arabidopsis thaliana (L.) Heynh. (ecotype Wassilewskija) was used as bioindicators of two genotoxic substances: potassium dichromate and dihydrophenanthrene. Inhibition of seed germination was observed with both pollutants. AFLP analysis (i) indicated that both substances are genotoxic, (ii) showed that dihydrophenanthrene induces DNA changes in different target sequences than potassium dichromate, (iii) quantified the genotoxic effect using cluster analysis by comparing DNA from treated plants with that of control plants. On the basis of these considerations we suggest that AFLP method is a powerful tool for measuring qualitative and quantitative genotoxic activity due to environmental pollutants. AFLP method can be applied to a wide range of bioindicator organisms and may become a universal methodology to identify target genes for specific genotoxic agents. This could open up possibilities for designing specifically targeted assays and new approaches to risk assessment.","AFLP analysis as biomarker of exposure to organic and inorganic genotoxic substances in plants Abs: In recent years several plant species have been in use as bioindicators and several tests have been developed to evaluate the toxicity of environmental pollutants in vegetal organisms. In the present paper Arabidopsis thaliana (L.) Heynh. (ecotype Wassilewskija) was used as bioindicators of two genotoxic substances: potassium dichromate and dihydrophenanthrene. Inhibition of seed germination was observed with both pollutants. AFLP analysis (i) indicated that both substances are genotoxic, (ii) showed that dihydrophenanthrene induces DNA changes in different target sequences than potassium dichromate, (iii) quantified the genotoxic effect using cluster analysis by comparing DNA from treated plants with that of control plants. On the basis of these considerations we suggest that AFLP method is a powerful tool for measuring qualitative and quantitative genotoxic activity due to environmental pollutants. AFLP method can be applied to a wide range of bioindicator organisms and may become a universal methodology to identify target genes for specific genotoxic agents. This could open up possibilities for designing specifically targeted assays and new approaches to risk assessment."
1234386,Fortepiani et al. 2003,Effect of losartan on renal microvasculature during chronic inhibition of nitric oxide visualized by micro-CT,"Chronic inhibition of nitric oxide (NO) synthase with the competitive l-arginine analog NG-nitro-l-arginine methyl ester (l-NAME) leads to an elevated systemic blood pressure and reduction in renal blood flow without significant changes in urinary sodium and water excretion. Simultaneous administration of ANG II AT1 receptor antagonist losartan and l-NAME prevents the alterations in blood pressure and renal hemodynamics. Microcomputed tomography (micro-CT) was used to investigate the role of ANG II in the changes of renal microvasculature during chronic NO inhibition. Sprague-Dawley rats were given l-NAME with or without AT1 receptor antagonist losartan (40 mg. kg-1. day-1 each) in their drinking water for 19 days. Kidneys from each group (control, l-NAME-, and l-NAME + losartan-treated rats) were perfusion-fixed in situ, infused with a silicon-based polymer containing lead chromate, and scanned by micro-CT. The microvasculature in the reconstructed three-dimensional renal images was studied using computerized analytic techniques. Kidneys of l-NAME-treated rats had significantly fewer normal glomeruli (28,824 +/- 838) than those of control rats (36,266 +/- 3,572). Losartan normalized the number to control values (34,094 +/- 1,536). The amount of vasculature in the cortex, outer medulla, and inner medulla of l-NAME-treated rats was about two-thirds that of control rats; losartan normalized the values to control levels. These data indicate that chronic treatment with the NO synthase inhibitor l-NAME produces a generalized rarefaction of renal capillaries. Because simultaneous AT1 receptor blockade abolished those changes, the data suggest that the reduction in vasculature is mediated by ANG II through AT1 receptors.","Effect of losartan on renal microvasculature during chronic inhibition of nitric oxide visualized by micro-CT Abs: Chronic inhibition of nitric oxide (NO) synthase with the competitive l-arginine analog NG-nitro-l-arginine methyl ester (l-NAME) leads to an elevated systemic blood pressure and reduction in renal blood flow without significant changes in urinary sodium and water excretion. Simultaneous administration of ANG II AT1 receptor antagonist losartan and l-NAME prevents the alterations in blood pressure and renal hemodynamics. Microcomputed tomography (micro-CT) was used to investigate the role of ANG II in the changes of renal microvasculature during chronic NO inhibition. Sprague-Dawley rats were given l-NAME with or without AT1 receptor antagonist losartan (40 mg. kg-1. day-1 each) in their drinking water for 19 days. Kidneys from each group (control, l-NAME-, and l-NAME + losartan-treated rats) were perfusion-fixed in situ, infused with a silicon-based polymer containing lead chromate, and scanned by micro-CT. The microvasculature in the reconstructed three-dimensional renal images was studied using computerized analytic techniques. Kidneys of l-NAME-treated rats had significantly fewer normal glomeruli (28,824 +/- 838) than those of control rats (36,266 +/- 3,572). Losartan normalized the number to control values (34,094 +/- 1,536). The amount of vasculature in the cortex, outer medulla, and inner medulla of l-NAME-treated rats was about two-thirds that of control rats; losartan normalized the values to control levels. These data indicate that chronic treatment with the NO synthase inhibitor l-NAME produces a generalized rarefaction of renal capillaries. Because simultaneous AT1 receptor blockade abolished those changes, the data suggest that the reduction in vasculature is mediated by ANG II through AT1 receptors."
1234385,Geetha et al. 2003,Evaluation of antioxidant activity of leaf extract of Seabuckthorn (Hippophae rhamnoides L.) on chromium(VI) induced oxidative stress in albino rats,"The present study reports the antioxidant activity of Seabuckthorn (Hippophae rhamnoides), family Elaegnaceae, on chromium induced oxidative stress in male albino rats. Oxidative stress was induced in the rats by force-feeding of potassium dichromate equivalent to a dose of 30mg/kg body weight (BW) of chromium(VI) for 30 days. Administration of chromium decreased the body weight and increased organ to body weight ratio significantly. Chromium treatment significantly decreased reduced glutathione (GSH), and increased malondialdehyde (MDA) and creatine phosphokinase (CPK) levels; further it also enhanced glutamate oxaloacetate transferase (GOT) and glutamate pyruvate transferase (GPT) levels in the serum. Different doses of the alcoholic leaf extract of Seabuckthorn were evaluated for the protection against the chromium induced oxidative stress. The results show that the leaf extract at a concentration of 100 and 250mg/kg BW protected the animals from the chromium induced oxidative injury significantly.","Evaluation of antioxidant activity of leaf extract of Seabuckthorn (Hippophae rhamnoides L.) on chromium(VI) induced oxidative stress in albino rats Abs: The present study reports the antioxidant activity of Seabuckthorn (Hippophae rhamnoides), family Elaegnaceae, on chromium induced oxidative stress in male albino rats. Oxidative stress was induced in the rats by force-feeding of potassium dichromate equivalent to a dose of 30mg/kg body weight (BW) of chromium(VI) for 30 days. Administration of chromium decreased the body weight and increased organ to body weight ratio significantly. Chromium treatment significantly decreased reduced glutathione (GSH), and increased malondialdehyde (MDA) and creatine phosphokinase (CPK) levels; further it also enhanced glutamate oxaloacetate transferase (GOT) and glutamate pyruvate transferase (GPT) levels in the serum. Different doses of the alcoholic leaf extract of Seabuckthorn were evaluated for the protection against the chromium induced oxidative stress. The results show that the leaf extract at a concentration of 100 and 250mg/kg BW protected the animals from the chromium induced oxidative injury significantly."
1234384,Rani et al. 2003,"Common allergens in shoe dermatitis: our experience in Lahore, Pakistan","<strong>BACKGROUND: </strong>Shoe dermatitis is a form of contact dermatitis resulting from exposure to shoes. Different chemicals, in conjunction with a hot and humid environment within the shoe, give rise to allergic or irritant dermatitis. Allergic shoe dermatitis is commonly caused by constituents of rubber, leather, adhesives, and rarely by linings and dyes.<br /><br /><strong>AIM: </strong>To determine the frequency of various allergens in shoe dermatitis in our patients.<br /><br /><strong>METHODS: </strong>One hundred and nine patients suspected of having contact dermatitis due to shoe allergens were included. All patients were patch tested with the Shoe series and European Standard series. Patches were applied on the upper back and removed after 48 h. Results were read at 48, 72, and 120 h and interpreted according to International Contact Dermatitis Research Group (ICDRG) criteria.<br /><br /><strong>RESULTS: </strong>Of the 119 patients, 87 (73%) reacted positively to various allergens, 48% of whom showed polysensitivity. Glues (33.6%), particularly para-tert-butylphenol formaldehyde resin (PTBP-FR) (26.9%), were the leading cause of shoe dermatitis. Other allergens were leather chemicals (26.4%), potassium dichromate (16.18%), rubber allergens (7.6%), and dyes (7.6%). Shoe scrapings tested positive in 26.3% of patients. Other common allergens were nickel sulfate (22.7%), neomycin sulfate (10.1%), and cobalt chloride (8.4%).<br /><br /><strong>CONCLUSIONS: </strong>Considering the diversity of allergens, all patients presenting with shoe dermatitis should be patch tested with the Shoe series and a standard series to determine the etiologic allergens.","Common allergens in shoe dermatitis: our experience in Lahore, Pakistan Abs: <strong>BACKGROUND: </strong>Shoe dermatitis is a form of contact dermatitis resulting from exposure to shoes. Different chemicals, in conjunction with a hot and humid environment within the shoe, give rise to allergic or irritant dermatitis. Allergic shoe dermatitis is commonly caused by constituents of rubber, leather, adhesives, and rarely by linings and dyes.<br /><br /><strong>AIM: </strong>To determine the frequency of various allergens in shoe dermatitis in our patients.<br /><br /><strong>METHODS: </strong>One hundred and nine patients suspected of having contact dermatitis due to shoe allergens were included. All patients were patch tested with the Shoe series and European Standard series. Patches were applied on the upper back and removed after 48 h. Results were read at 48, 72, and 120 h and interpreted according to International Contact Dermatitis Research Group (ICDRG) criteria.<br /><br /><strong>RESULTS: </strong>Of the 119 patients, 87 (73%) reacted positively to various allergens, 48% of whom showed polysensitivity. Glues (33.6%), particularly para-tert-butylphenol formaldehyde resin (PTBP-FR) (26.9%), were the leading cause of shoe dermatitis. Other allergens were leather chemicals (26.4%), potassium dichromate (16.18%), rubber allergens (7.6%), and dyes (7.6%). Shoe scrapings tested positive in 26.3% of patients. Other common allergens were nickel sulfate (22.7%), neomycin sulfate (10.1%), and cobalt chloride (8.4%).<br /><br /><strong>CONCLUSIONS: </strong>Considering the diversity of allergens, all patients presenting with shoe dermatitis should be patch tested with the Shoe series and a standard series to determine the etiologic allergens."
1234383,Vayssieres et al. 2001,Aqueous chemical growth of alpha-Fe2O3-alpha-Cr2O3 nanocomposite thin films,"We are reporting here on the inexpensive fabrication and optical properties of an iron(III) oxide-chromium(III) oxide nanocomposite thin film of corundum crystal structure. Its novel and unique-designed architecture consists of uniformed, well-defined and oriented nanorods of Hematite (alpha-Fe2O3) of 50 nm in diameter and 500 nm in length and homogeneously distributed nonaggregated monodisperse spherical nanoparticles of Eskolaite (alpha-Cr2O3) of 250 nm in diameter. This alpha-Fe2O3-alpha-Cr2O3 nanocomposite thin film is obtained by growing, directly onto transparent polycrystalline conducting substrate, an oriented layer of hematite nanorods and growing subsequently, the eskolaite layer. The synthesis is carried out by a template-free, low-temperature, multilayer thin film coating process using aqueous solution of metal salts as precursors. Almost 100% of the light is absorbed by the composite film between 300 and 525 nm and 40% at 800 nm which yields great expectations as photoanode materials for photovoltaic cells and photocatalytic devices.","Aqueous chemical growth of alpha-Fe2O3-alpha-Cr2O3 nanocomposite thin films Abs: We are reporting here on the inexpensive fabrication and optical properties of an iron(III) oxide-chromium(III) oxide nanocomposite thin film of corundum crystal structure. Its novel and unique-designed architecture consists of uniformed, well-defined and oriented nanorods of Hematite (alpha-Fe2O3) of 50 nm in diameter and 500 nm in length and homogeneously distributed nonaggregated monodisperse spherical nanoparticles of Eskolaite (alpha-Cr2O3) of 250 nm in diameter. This alpha-Fe2O3-alpha-Cr2O3 nanocomposite thin film is obtained by growing, directly onto transparent polycrystalline conducting substrate, an oriented layer of hematite nanorods and growing subsequently, the eskolaite layer. The synthesis is carried out by a template-free, low-temperature, multilayer thin film coating process using aqueous solution of metal salts as precursors. Almost 100% of the light is absorbed by the composite film between 300 and 525 nm and 40% at 800 nm which yields great expectations as photoanode materials for photovoltaic cells and photocatalytic devices."
1234380,Santos et al. 2003,Effect of somatic cell count on proteolysis and lipolysis in pasteurized fluid milk during shelf-life storage,"The general goal of this research was to provide fluid milk processors with data to enable them to estimate the economic benefits they might derive from longer fluid milk shelf-life or new marketing opportunities due to a reduction in raw milk SCC. The study objectives were: 1) to measure the time in days for pasteurized homogenized 2% milk to achieve a level of lipolysis and proteolysis caused by native milk enzymes present in milks of different somatic cell count (SCC) at 0.5 and 6 degrees C that would be sufficient to produce an off-flavor, 2) to determine whether milk fat content (i.e., 1, 2, and 3.25%) influences the level of proteolysis or lipolysis caused by native milk enzymes at 6 degrees C, and 3) to determine the time in days for milks containing 2% fat with different SCC to undergo sufficient lipolysis or proteolysis to produce an off-flavor due to the combination of the action of native milk enzymes and microbial growth at 0.5 and 6 degrees C. In experiment 1, pasteurized, homogenized milks, containing 2% fat were prepared from raw milk containing four different SCC levels from &lt; 100,000 to &gt; 1,000,000 cells/ml. Each of the four milks was stored at 0.5 and 6 degrees C for 61 d. In experiment 2, pasteurized, homogenized milks containing 1, 2, and 3.25% fat were prepared starting from two raw milks containing two different SCC levels, one &lt; 100,000 and the other &gt; 1,000,000 cells/ml. In experiment 3, pasteurized, homogenized 2% fat milks were prepared starting from raw milks containing two different SCC levels, one &lt; 100,000 and the other &gt; 1,000,000 cells/ml. For experiments 1 and 2, all milks were preserved with potassium dichromate to prevent microbial growth but to allow the activity of native milk proteases and lipases during storage. For experiment 3, one set of milk was preserved with potassium dichromate to prevent microbial growth but to allow the activity of native milk proteases and lipases, and a second set of milk was unpreserved during storage at 0.5 and 6 degrees C for 29 d. Based on previous work, an off-flavor due to proteolysis was detected by 50% of panelists when the decrease in casein as a percentage of true protein (CN/TP) was &gt; 4.76%. Our data indicated (assuming 50% of consumers would detect an off-flavor when CN/TP decreases 5%) that pasteurized milk containing 2% fat would develop an off-flavor at a time long after 61 and at 54 d for the low SCC milk, and at about 54 and 19 d for the high SCC milk, at 0.5 and 6 degrees C, respectively. Previous research reported that 34% of panelists could detect an off-flavor in milk containing 2% fat due to lipolysis at a (free fatty acid) FFA concentration of 0.25 meq/kg of milk. Based on these results, it was estimated in the present study that 34% of panelists would detect an off-flavor in a 2% fat pasteurized milk with low SCC at a time long after 61 and just after 61 d at 0.5 and 6 degrees C, respectively, while for milk with high SCC, an off-flavor would be detected by 34% of panelists at slightly longer than 61 and 35 d at 0.5 and 6 degrees C, respectively. The combination of low SCC milk and low storage temperature when coupled with processing technology to produce very low initial bacteria count in fluid milk could produce fluid milk that will maintain flavor quality for more than 61 d of storage at temperatures &lt; 6 degrees C.","Effect of somatic cell count on proteolysis and lipolysis in pasteurized fluid milk during shelf-life storage Abs: The general goal of this research was to provide fluid milk processors with data to enable them to estimate the economic benefits they might derive from longer fluid milk shelf-life or new marketing opportunities due to a reduction in raw milk SCC. The study objectives were: 1) to measure the time in days for pasteurized homogenized 2% milk to achieve a level of lipolysis and proteolysis caused by native milk enzymes present in milks of different somatic cell count (SCC) at 0.5 and 6 degrees C that would be sufficient to produce an off-flavor, 2) to determine whether milk fat content (i.e., 1, 2, and 3.25%) influences the level of proteolysis or lipolysis caused by native milk enzymes at 6 degrees C, and 3) to determine the time in days for milks containing 2% fat with different SCC to undergo sufficient lipolysis or proteolysis to produce an off-flavor due to the combination of the action of native milk enzymes and microbial growth at 0.5 and 6 degrees C. In experiment 1, pasteurized, homogenized milks, containing 2% fat were prepared from raw milk containing four different SCC levels from &lt; 100,000 to &gt; 1,000,000 cells/ml. Each of the four milks was stored at 0.5 and 6 degrees C for 61 d. In experiment 2, pasteurized, homogenized milks containing 1, 2, and 3.25% fat were prepared starting from two raw milks containing two different SCC levels, one &lt; 100,000 and the other &gt; 1,000,000 cells/ml. In experiment 3, pasteurized, homogenized 2% fat milks were prepared starting from raw milks containing two different SCC levels, one &lt; 100,000 and the other &gt; 1,000,000 cells/ml. For experiments 1 and 2, all milks were preserved with potassium dichromate to prevent microbial growth but to allow the activity of native milk proteases and lipases during storage. For experiment 3, one set of milk was preserved with potassium dichromate to prevent microbial growth but to allow the activity of native milk proteases and lipases, and a second set of milk was unpreserved during storage at 0.5 and 6 degrees C for 29 d. Based on previous work, an off-flavor due to proteolysis was detected by 50% of panelists when the decrease in casein as a percentage of true protein (CN/TP) was &gt; 4.76%. Our data indicated (assuming 50% of consumers would detect an off-flavor when CN/TP decreases 5%) that pasteurized milk containing 2% fat would develop an off-flavor at a time long after 61 and at 54 d for the low SCC milk, and at about 54 and 19 d for the high SCC milk, at 0.5 and 6 degrees C, respectively. Previous research reported that 34% of panelists could detect an off-flavor in milk containing 2% fat due to lipolysis at a (free fatty acid) FFA concentration of 0.25 meq/kg of milk. Based on these results, it was estimated in the present study that 34% of panelists would detect an off-flavor in a 2% fat pasteurized milk with low SCC at a time long after 61 and just after 61 d at 0.5 and 6 degrees C, respectively, while for milk with high SCC, an off-flavor would be detected by 34% of panelists at slightly longer than 61 and 35 d at 0.5 and 6 degrees C, respectively. The combination of low SCC milk and low storage temperature when coupled with processing technology to produce very low initial bacteria count in fluid milk could produce fluid milk that will maintain flavor quality for more than 61 d of storage at temperatures &lt; 6 degrees C."
1234379,Martínez et al. 2003,Effect of freezing on Fossomatic cell counting in ewe milk,"Using the Fossomatic method, a total of 10,072 analytical somatic cell count (SCC) observations were carried out on 4760 aliquots taken from 70 individual ewe milk samples with the objective of studying whether freezing showed significant differences of SCC in comparison with refrigeration, according to different analytical conditions. These conditions were four preservation procedures (without preservation, potassium dichromate, azidiol, and bronopol), two storage temperatures (refrigeration and freezing), five milk ages within storage (24 h postcollection in refrigeration, and 24 h, 15, 30, and 60 d postcollection in freezing), two thawing types (rapid and slow), and two analytical temperatures (40 and 60 degrees C). Preservation, storage, and analytical temperature, type of thawing and milk age within storage, and most of the interactions showed a significant effect on the SCC variation. On average, the SCC was lower after freezing than in refrigeration. This effect depended specifically on type of preservation and analytical temperature of milk. The SCC of milk unpreserved or preserved with bronopol or potassium dichromate, and analyzed at 40 degrees C, was not affected by freezing; however, use of azidiol as a preservative before freezing, and heating the milk to 60 degrees C following thawing resulted in significantly decreased SCC. Milk age had little quantitative influence on SCC of thawed milk. The type of thawing (rapid and slow) did not significantly influence SCC of milk analyzed at 40 degrees C. As a result, when using properly handled samples, the Fossomatic method could be used to enumerate SCC in samples frozen over the 60 d.","Effect of freezing on Fossomatic cell counting in ewe milk Abs: Using the Fossomatic method, a total of 10,072 analytical somatic cell count (SCC) observations were carried out on 4760 aliquots taken from 70 individual ewe milk samples with the objective of studying whether freezing showed significant differences of SCC in comparison with refrigeration, according to different analytical conditions. These conditions were four preservation procedures (without preservation, potassium dichromate, azidiol, and bronopol), two storage temperatures (refrigeration and freezing), five milk ages within storage (24 h postcollection in refrigeration, and 24 h, 15, 30, and 60 d postcollection in freezing), two thawing types (rapid and slow), and two analytical temperatures (40 and 60 degrees C). Preservation, storage, and analytical temperature, type of thawing and milk age within storage, and most of the interactions showed a significant effect on the SCC variation. On average, the SCC was lower after freezing than in refrigeration. This effect depended specifically on type of preservation and analytical temperature of milk. The SCC of milk unpreserved or preserved with bronopol or potassium dichromate, and analyzed at 40 degrees C, was not affected by freezing; however, use of azidiol as a preservative before freezing, and heating the milk to 60 degrees C following thawing resulted in significantly decreased SCC. Milk age had little quantitative influence on SCC of thawed milk. The type of thawing (rapid and slow) did not significantly influence SCC of milk analyzed at 40 degrees C. As a result, when using properly handled samples, the Fossomatic method could be used to enumerate SCC in samples frozen over the 60 d."
1234375,Barrera et al. 2003,Protective effect of SnCl2 on K2Cr2O7-induced nephrotoxicity in rats: the indispensability of HO-1 preinduction and lack of association with some antioxidant enzymes,"We have shown that the ameliorative effect of stannous chloride (SnCl2) pretreatment on potassium dichromate (K2Cr2O7)-induced renal damage 24 h after K2Cr2O7 injection was associated with the induction of heme oxygenase-1 (HO-1). In this work we evaluated: (a) if the protective effect of SnCl2 (given 12 h before K2Cr2O7) is associated with changes in the renal activity of HO-1, superoxide dismutase (SOD), glutathione peroxidase (GPx), glutathione reductase (GR), and catalase (CAT) 24 and 48 h after K2Cr2O7 injection, and (b) if HO-1 induction is indispensable before K2Cr2O7 injection. It was found that the protective effect of SnCl2 on renal function was observed both at 24 and 48 h reaching its maximum at 24 h when HO-1 expression was higher. Cu,Zn-SOD, Mn-SOD, and GR activities remained unchanged whereas GPx and CAT activities decreased at 48 h in K2Cr2O7-treated rats. The activity of Cu,Zn-SOD, Mn-SOD, GPx, CAT, and GR was unchanged in the SnCl2-treated rats. To fulfill the objective (b) groups of rats treated with K2Cr2O7 and SnCl2 (given at the same time or 12 h after K2Cr2O7) were studied 24 h after K2Cr2O7-injection. The simultaneous injections of SnCl2 and K2Cr2O7 had no protective effect whereas the injection of SnCl2 12 h after K2Cr2O7 exacerbated renal damage. In conclusion, the protective effect of SnCl2 on K2Cr2O7-induced nephrotoxicity is associated with HO-1 induction and not with other antioxidant enzymes (Cu,Zn-SOD, Mn-SOD, GPx, GR, and CAT) and SnCl2 has a preventive and not a therapeutic effect on renal damage induced by K2Cr2O7.","Protective effect of SnCl2 on K2Cr2O7-induced nephrotoxicity in rats: the indispensability of HO-1 preinduction and lack of association with some antioxidant enzymes Abs: We have shown that the ameliorative effect of stannous chloride (SnCl2) pretreatment on potassium dichromate (K2Cr2O7)-induced renal damage 24 h after K2Cr2O7 injection was associated with the induction of heme oxygenase-1 (HO-1). In this work we evaluated: (a) if the protective effect of SnCl2 (given 12 h before K2Cr2O7) is associated with changes in the renal activity of HO-1, superoxide dismutase (SOD), glutathione peroxidase (GPx), glutathione reductase (GR), and catalase (CAT) 24 and 48 h after K2Cr2O7 injection, and (b) if HO-1 induction is indispensable before K2Cr2O7 injection. It was found that the protective effect of SnCl2 on renal function was observed both at 24 and 48 h reaching its maximum at 24 h when HO-1 expression was higher. Cu,Zn-SOD, Mn-SOD, and GR activities remained unchanged whereas GPx and CAT activities decreased at 48 h in K2Cr2O7-treated rats. The activity of Cu,Zn-SOD, Mn-SOD, GPx, CAT, and GR was unchanged in the SnCl2-treated rats. To fulfill the objective (b) groups of rats treated with K2Cr2O7 and SnCl2 (given at the same time or 12 h after K2Cr2O7) were studied 24 h after K2Cr2O7-injection. The simultaneous injections of SnCl2 and K2Cr2O7 had no protective effect whereas the injection of SnCl2 12 h after K2Cr2O7 exacerbated renal damage. In conclusion, the protective effect of SnCl2 on K2Cr2O7-induced nephrotoxicity is associated with HO-1 induction and not with other antioxidant enzymes (Cu,Zn-SOD, Mn-SOD, GPx, GR, and CAT) and SnCl2 has a preventive and not a therapeutic effect on renal damage induced by K2Cr2O7."
1234374,Rodríguez et al. 2003,Role of thyroid hormones on the synthesis and release of atrial natriuretic peptide in rats with acute renal failure,"<strong>BACKGROUND/AIMS: </strong>High atrial natriuretic peptide (ANP) serum levels are seen in acute renal failure (ARF) due to impaired ANP clearance, but the response of ANP to blood volume expansion is blunted. ARF-associated hypothyroidism influences ANP clearance but it may also play a role in the synthesis and release of ANP because in primary hypothyroidism both mechanisms are disturbed. The aim of this study is to analyze whether thyroxin (T4) supplementation improves the synthesis and release of ANP in ARF.<br /><br /><strong>METHODS: </strong>Four groups of rats were studied: group C (control); group ARF; Group ARF-T4 (ARF supplemented with T4), and group Tx (thyroidectomized). Serum creatinine (SCr), creatinine clearance (CrCl), total T4, total triiodothyronin (T3), plasma ANP, ANP response to acute saline load and atrial content of mRNA-ANP were measured 5 days after ARF induction with potassium dichromate.<br /><br /><strong>RESULTS: </strong>CrCl was 1.8 +/- 0.4 ml/min in group C, and it significantly dropped to 0.6 +/- 0.5 in ARF (p &lt; 0.01), T4 improved it (1.7 +/- 0.7 in ARF-T4, p &lt; 0.01) and Tx did not change it. Plasma ANP was higher in ARF as compared with C (152 +/- 23 vs. 52 +/- 21 fmol/l, p &lt; 0.01). In ARF-T4, ANP was higher than in C but lower than in ARF (85 +/- 28 fmol/l, p &lt; 0.01). No changes were observed in Tx rats (48 +/- 17 fmol/l). The atrial content of mRNA-ANP was 0.06 +/- 0.025 mRNA-ANP/mRNA-beta-actin ratio units in group C, it was higher in ARF (0.13 +/- 0.025, p &lt; 0.01) and lower in Tx (0.04 +/- 0.01, p &lt; 0.05) as compared to C. Supplementation with T4 increased the mRNA-ANF content (0.18 +/- 0.2 mRNA-ANP/mRNA-beta-actin ratio units, p &lt; 0.05) over ARF. Plasma ANP response to saline load was 45 +/- 7% in C, but it was reduced in ARF and Tx (20 +/- 10 and 26 +/- 10%, p &lt; 0.01). In ARF-T4 the response was restored (36 +/- 9%, p &lt; 0.01 vs. ARF).<br /><br /><strong>CONCLUSION: </strong>Thyroid hormones modulate the synthesis and release of ANP in ARF. Although the effect is probably direct, T4-induced amelioration of renal damage may also play a significant role by improving the uremic milieu.","Role of thyroid hormones on the synthesis and release of atrial natriuretic peptide in rats with acute renal failure Abs: <strong>BACKGROUND/AIMS: </strong>High atrial natriuretic peptide (ANP) serum levels are seen in acute renal failure (ARF) due to impaired ANP clearance, but the response of ANP to blood volume expansion is blunted. ARF-associated hypothyroidism influences ANP clearance but it may also play a role in the synthesis and release of ANP because in primary hypothyroidism both mechanisms are disturbed. The aim of this study is to analyze whether thyroxin (T4) supplementation improves the synthesis and release of ANP in ARF.<br /><br /><strong>METHODS: </strong>Four groups of rats were studied: group C (control); group ARF; Group ARF-T4 (ARF supplemented with T4), and group Tx (thyroidectomized). Serum creatinine (SCr), creatinine clearance (CrCl), total T4, total triiodothyronin (T3), plasma ANP, ANP response to acute saline load and atrial content of mRNA-ANP were measured 5 days after ARF induction with potassium dichromate.<br /><br /><strong>RESULTS: </strong>CrCl was 1.8 +/- 0.4 ml/min in group C, and it significantly dropped to 0.6 +/- 0.5 in ARF (p &lt; 0.01), T4 improved it (1.7 +/- 0.7 in ARF-T4, p &lt; 0.01) and Tx did not change it. Plasma ANP was higher in ARF as compared with C (152 +/- 23 vs. 52 +/- 21 fmol/l, p &lt; 0.01). In ARF-T4, ANP was higher than in C but lower than in ARF (85 +/- 28 fmol/l, p &lt; 0.01). No changes were observed in Tx rats (48 +/- 17 fmol/l). The atrial content of mRNA-ANP was 0.06 +/- 0.025 mRNA-ANP/mRNA-beta-actin ratio units in group C, it was higher in ARF (0.13 +/- 0.025, p &lt; 0.01) and lower in Tx (0.04 +/- 0.01, p &lt; 0.05) as compared to C. Supplementation with T4 increased the mRNA-ANF content (0.18 +/- 0.2 mRNA-ANP/mRNA-beta-actin ratio units, p &lt; 0.05) over ARF. Plasma ANP response to saline load was 45 +/- 7% in C, but it was reduced in ARF and Tx (20 +/- 10 and 26 +/- 10%, p &lt; 0.01). In ARF-T4 the response was restored (36 +/- 9%, p &lt; 0.01 vs. ARF).<br /><br /><strong>CONCLUSION: </strong>Thyroid hormones modulate the synthesis and release of ANP in ARF. Although the effect is probably direct, T4-induced amelioration of renal damage may also play a significant role by improving the uremic milieu."
1234372,Suman and  Reddy 2003,Pattern of contact sensitivity in Indian patients with hand eczema,"One hundred consecutive patients with hand eczema were patch tested with the Indian Standard Series and indigenous antigens after a detailed history and clinical examination. Both sexes were involved and the majority of them were in the age group between 20-39 years (56%). Their occupational profile varied in order of frequency from household work (37%), to masons (14%), students (11%), factory workers (7%), and others (31%). Itching was the most common presenting complaint (93%). A history of atopy was found in 36% of the patients. The predominant sites involved were the palms (43%), followed by fingers (32%), dorsum (17%), and the entire hand (8%). Dry, scaly skin was the most common morphological picture, followed by hyperpigmentation, fissuring, and lichenification. Based on history, clinical examination and patch test results, the diagnosis was made as allergic contact dermatitis in 67% of cases and irritant contact dermatitis in 15% of cases. Positive patch tests with one or more allergens were noted in 67% of the patients. Vegetables (21%) were found to be the most common sensitizers, followed by nickel sulphate (20%), potassium dichromate (18%), and others. Wet work, soaps, and detergents were found to be the most offending irritants. The present study confirmed the fact that hand eczema is a multifactorial disease caused by both irritants and allergens.","Pattern of contact sensitivity in Indian patients with hand eczema Abs: One hundred consecutive patients with hand eczema were patch tested with the Indian Standard Series and indigenous antigens after a detailed history and clinical examination. Both sexes were involved and the majority of them were in the age group between 20-39 years (56%). Their occupational profile varied in order of frequency from household work (37%), to masons (14%), students (11%), factory workers (7%), and others (31%). Itching was the most common presenting complaint (93%). A history of atopy was found in 36% of the patients. The predominant sites involved were the palms (43%), followed by fingers (32%), dorsum (17%), and the entire hand (8%). Dry, scaly skin was the most common morphological picture, followed by hyperpigmentation, fissuring, and lichenification. Based on history, clinical examination and patch test results, the diagnosis was made as allergic contact dermatitis in 67% of cases and irritant contact dermatitis in 15% of cases. Positive patch tests with one or more allergens were noted in 67% of the patients. Vegetables (21%) were found to be the most common sensitizers, followed by nickel sulphate (20%), potassium dichromate (18%), and others. Wet work, soaps, and detergents were found to be the most offending irritants. The present study confirmed the fact that hand eczema is a multifactorial disease caused by both irritants and allergens."
1234371,Sharma et al. 2003,Fatal potassium dichromate ingestion,,Fatal potassium dichromate ingestion Abs: 
1234370,Speit and  Bonzheim 2003,Genotoxic and protective effects of hyperbaric oxygen in A549 lung cells,"The human lung cell line A549 is frequently used as an in vitro model for studying lung toxicity and genotoxicity of environmental mutagens and carcinogens. Hyperbaric oxygen (HBO) treatment has been shown to be an excellent model for investigating the genetic consequences of oxidative stress in vitro and in vivo. We have now studied the genotoxic effects of and adaptive protection by HBO in A549 cells. Using the alkaline Comet assay, our results show that HBO exposure directly induces DNA damage but reduces the DNA-damaging effect of a second HBO treatment of the cells 24 h later. HBO pretreatment also reduces potassium chromate-induced genotoxicity in A549 cells. Heme oxygenase-1 (HO-1) protein level is increased 24 h after HBO exposure and inhibition of HO-1 activity by tin-mesoporphyrin increased HBO genotoxicity. These results are in accordance with previous findings suggesting an involvement of HO-1 in the adaptive protection. Our study indicates that A549 cells are an appropriate cell culture system for the evaluation of genetic effects induced by HBO in lung cells.","Genotoxic and protective effects of hyperbaric oxygen in A549 lung cells Abs: The human lung cell line A549 is frequently used as an in vitro model for studying lung toxicity and genotoxicity of environmental mutagens and carcinogens. Hyperbaric oxygen (HBO) treatment has been shown to be an excellent model for investigating the genetic consequences of oxidative stress in vitro and in vivo. We have now studied the genotoxic effects of and adaptive protection by HBO in A549 cells. Using the alkaline Comet assay, our results show that HBO exposure directly induces DNA damage but reduces the DNA-damaging effect of a second HBO treatment of the cells 24 h later. HBO pretreatment also reduces potassium chromate-induced genotoxicity in A549 cells. Heme oxygenase-1 (HO-1) protein level is increased 24 h after HBO exposure and inhibition of HO-1 activity by tin-mesoporphyrin increased HBO genotoxicity. These results are in accordance with previous findings suggesting an involvement of HO-1 in the adaptive protection. Our study indicates that A549 cells are an appropriate cell culture system for the evaluation of genetic effects induced by HBO in lung cells."
1234369,Panda and  Malakar 2003,Lichen nitidus-like allergic contact dermatitis - a clinicopathological study,,Lichen nitidus-like allergic contact dermatitis - a clinicopathological study Abs: 
1234368,Labra et al. 2004,Genetic and DNA-methylation changes induced by potassium dichromate in Brassica napus L,"This study evaluated genetic and DNA methylation alteration induced by potassium dichromate in Brassica napus L. plants. Amplified fragment length polymorphism (AFLP) and selective amplification of polymorphic loci (SAMPL) tests revealed dose-related increases in sequence alterations in plantlets exposed to 10-200 mg/l potassium dichromate. Individual plantlets exposed to chromium under similar conditions showed different AFLP and SAMPL DNA profiles. These observations suggest random DNA mutation in response to potassium dichromate and argue against preferential sites for mutation. DNA methylation changes in response to chromium treatment were also evaluated. Two complementary approaches were applied: (i) immunolabelling, using a monoclonal antibody against 5-methylcytosine; and (ii) methylation-sensitive amplified polymorphism (MSAP). Immunolabelling showed cytosine-hypermethylation in the Brassica napus L. genome when plants were treated with potassium dichromate. MSAP analysis showed extensive methylation changes in CCGG-sequences, with the net result being genome-wide hypermethylation. These results showed a clear DNA alteration in plants as a response to chromium exposure and the effect was dose-dependent. DNA polymorphism detected by different markers supports the effectiveness of the use of these tools for the investigation of environmental toxicology and for evaluating the concentration of pollutants by DNA analysis in plants.","Genetic and DNA-methylation changes induced by potassium dichromate in Brassica napus L Abs: This study evaluated genetic and DNA methylation alteration induced by potassium dichromate in Brassica napus L. plants. Amplified fragment length polymorphism (AFLP) and selective amplification of polymorphic loci (SAMPL) tests revealed dose-related increases in sequence alterations in plantlets exposed to 10-200 mg/l potassium dichromate. Individual plantlets exposed to chromium under similar conditions showed different AFLP and SAMPL DNA profiles. These observations suggest random DNA mutation in response to potassium dichromate and argue against preferential sites for mutation. DNA methylation changes in response to chromium treatment were also evaluated. Two complementary approaches were applied: (i) immunolabelling, using a monoclonal antibody against 5-methylcytosine; and (ii) methylation-sensitive amplified polymorphism (MSAP). Immunolabelling showed cytosine-hypermethylation in the Brassica napus L. genome when plants were treated with potassium dichromate. MSAP analysis showed extensive methylation changes in CCGG-sequences, with the net result being genome-wide hypermethylation. These results showed a clear DNA alteration in plants as a response to chromium exposure and the effect was dose-dependent. DNA polymorphism detected by different markers supports the effectiveness of the use of these tools for the investigation of environmental toxicology and for evaluating the concentration of pollutants by DNA analysis in plants."
1234367,Surl et al. 2003,Viability of preserved Cryptosporidium baileyi oocysts,"The present study was undertaken to determine the viability and infectivity of oocysts of Cryptosporidium baileyi that had been stored from 1 to 40 months at 4 degrees C preserved in 2.5% potassium dichromate solution. Oocysts of C. baileyi were purified from the feces of experimentally infected chickens using discontinuous sucrose gradients. Subsequently, the purified oocysts were suspended in 2.5% potassium dichromate solution at a concentration of 1 x 10(7) organism/ml, and their viabilities were assessed by nucleic acid staining, histologic examination, and infectivity to 2-day-old chickens. All chickens inoculated with oocysts that had been stored for 1-18 months developed patent infections, while chickens infected with older oocysts remained uninfected. Between 5.8% and 82.2% of the oocysts, stored at 4 degrees C in 2.5% potassium dichromate solution, were found to be viable, as determined by nucleic acid staining. Parasite colonization in the bursa of Fabricius was detected in the microvillus border of bursal epithelium. The finding that C. baileyi oocysts remain infective to chickens for at least 18 months offers important time-saving advantages to investigators who frequently require large numbers of oocysts.","Viability of preserved Cryptosporidium baileyi oocysts Abs: The present study was undertaken to determine the viability and infectivity of oocysts of Cryptosporidium baileyi that had been stored from 1 to 40 months at 4 degrees C preserved in 2.5% potassium dichromate solution. Oocysts of C. baileyi were purified from the feces of experimentally infected chickens using discontinuous sucrose gradients. Subsequently, the purified oocysts were suspended in 2.5% potassium dichromate solution at a concentration of 1 x 10(7) organism/ml, and their viabilities were assessed by nucleic acid staining, histologic examination, and infectivity to 2-day-old chickens. All chickens inoculated with oocysts that had been stored for 1-18 months developed patent infections, while chickens infected with older oocysts remained uninfected. Between 5.8% and 82.2% of the oocysts, stored at 4 degrees C in 2.5% potassium dichromate solution, were found to be viable, as determined by nucleic acid staining. Parasite colonization in the bursa of Fabricius was detected in the microvillus border of bursal epithelium. The finding that C. baileyi oocysts remain infective to chickens for at least 18 months offers important time-saving advantages to investigators who frequently require large numbers of oocysts."
1234366,Hostynek and  Maibach 2004,Skin irritation potential of copper compounds,"Data on the dermal irritation by copper and its compounds is scant, and its irritancy has not been determined, e.g., in terms of an irritant dose ID50. Irritancy of copper can only be comparatively characterized in relation to other metal salts. A rank order for the irritancy of metal compounds can be inferred from the patch test concentrations recommended as non-irritating for the purpose of cutaneous allergy testing: potassium dichromate 0.5% in petrolatum; copper sulfate, cobalt chloride and palladium chloride ex equo: 1% in aqueous solution, and nickel sulfate: 5% in petrolatum.","Skin irritation potential of copper compounds Abs: Data on the dermal irritation by copper and its compounds is scant, and its irritancy has not been determined, e.g., in terms of an irritant dose ID50. Irritancy of copper can only be comparatively characterized in relation to other metal salts. A rank order for the irritancy of metal compounds can be inferred from the patch test concentrations recommended as non-irritating for the purpose of cutaneous allergy testing: potassium dichromate 0.5% in petrolatum; copper sulfate, cobalt chloride and palladium chloride ex equo: 1% in aqueous solution, and nickel sulfate: 5% in petrolatum."
1234364,Dickel et al. 2003,Multiple patch-test reactions: a pilot evaluation of a combination approach to visualize patterns of multiple sensitivity in patch-test databases and a proposal for a multiple sensitivity index,"<strong>BACKGROUND: </strong>The variety of patterns of multiple sensitivity in patch-test data remains poorly defined. Studies addressing this topic have primarily concerned the occurrence of pairs of allergens, and some reports hypothesize a predisposing factor that influences the individual sensitivity of patients to multiple reactions.<br /><br /><strong>OBJECTIVE: </strong>The aim of this study was to address this topic by reanalyzing a matched data set from two patch-test units in Cleveland, OH, and one unit in Cologne, Germany, focusing on multiple reactions to identical allergens of the standard screening trays over the same 4-year period. Methods: Based on the statistical FREQ procedure (SAS Institute Inc., Cary, NC), we propose a program for addressing the difficulties in computing and visualizing patterns of multiple sensitivity. Additionally, we propose the &quot;multiple sensitivity index&quot; (MSI) as an absolute measure for characterizing the occurrence of an allergen with others on a selected panel.<br /><br /><strong>RESULTS: </strong>For the seventeen allergens examined, 131072 possible combinations were evaluated in a total of 2881 patients. Of patients tested, 12.4% had multiple positive patch-test reactions to two to seven allergens. However, because of the small number of patients with the crucial number of possible combinations, no cluster patterns were evident in the three- to seven-allergen combinations. Pairs of allergens most frequently observed were nickel sulfate and potassium dichromate (n = 23), formaldehyde and quaternium-15 (n = 18), and nickel sulfate and formaldehyde (n = 13). We found that nickel sulfate, once again the most frequent sensitizer, occurred in the majority of noncombined cases (MSI = -0.280).<br /><br /><strong>CONCLUSION: </strong>Larger patch-test databases require evaluation to obtain further evidence of cluster patterns of multiple sensitivity and to validate the MSI.","Multiple patch-test reactions: a pilot evaluation of a combination approach to visualize patterns of multiple sensitivity in patch-test databases and a proposal for a multiple sensitivity index Abs: <strong>BACKGROUND: </strong>The variety of patterns of multiple sensitivity in patch-test data remains poorly defined. Studies addressing this topic have primarily concerned the occurrence of pairs of allergens, and some reports hypothesize a predisposing factor that influences the individual sensitivity of patients to multiple reactions.<br /><br /><strong>OBJECTIVE: </strong>The aim of this study was to address this topic by reanalyzing a matched data set from two patch-test units in Cleveland, OH, and one unit in Cologne, Germany, focusing on multiple reactions to identical allergens of the standard screening trays over the same 4-year period. Methods: Based on the statistical FREQ procedure (SAS Institute Inc., Cary, NC), we propose a program for addressing the difficulties in computing and visualizing patterns of multiple sensitivity. Additionally, we propose the &quot;multiple sensitivity index&quot; (MSI) as an absolute measure for characterizing the occurrence of an allergen with others on a selected panel.<br /><br /><strong>RESULTS: </strong>For the seventeen allergens examined, 131072 possible combinations were evaluated in a total of 2881 patients. Of patients tested, 12.4% had multiple positive patch-test reactions to two to seven allergens. However, because of the small number of patients with the crucial number of possible combinations, no cluster patterns were evident in the three- to seven-allergen combinations. Pairs of allergens most frequently observed were nickel sulfate and potassium dichromate (n = 23), formaldehyde and quaternium-15 (n = 18), and nickel sulfate and formaldehyde (n = 13). We found that nickel sulfate, once again the most frequent sensitizer, occurred in the majority of noncombined cases (MSI = -0.280).<br /><br /><strong>CONCLUSION: </strong>Larger patch-test databases require evaluation to obtain further evidence of cluster patterns of multiple sensitivity and to validate the MSI."
1234363,Trattner et al. 2003,Shoe contact dermatitis in Israel,"<strong>BACKGROUND: </strong>Patch testing with the shoe series may be useful for the diagnosis of shoe contact dermatitis.<br /><br /><strong>OBJECTIVE: </strong>The aim of the study was to verify the usefulness of the shoe series and the association of fungal infection with positive results in the shoe series.<br /><br /><strong>METHODS: </strong>A total of 140 patients with suspected shoe contact dermatitis underwent patch testing with the standard series and shoe series; 41 underwent mycologic examination.<br /><br /><strong>RESULTS: </strong>Positive results in the shoe series were noted in 58 patients (41.4%). The most common allergens were potassium dichromate (27.2%), nickel sulfate (11.9%), Kathon CG (10.9%), and 4-tert-butylphenol formaldehyde resin (8.7%). Of the 41 patients with suspected tinea pedis, 13 (32%) had positive mycologic findings and 9 (69.2%) also had a positive response to the shoe series. Of the patients with a negative result on mycologic examination, only 10 (35.7%) had a positive result in the shoe series.<br /><br /><strong>CONCLUSION: </strong>Our study indicates that all patients with foot dermatitis should undergo patch testing with the shoe series. Positive results in the shoe series seem to be more prevalent in patients with a fungal infection.","Shoe contact dermatitis in Israel Abs: <strong>BACKGROUND: </strong>Patch testing with the shoe series may be useful for the diagnosis of shoe contact dermatitis.<br /><br /><strong>OBJECTIVE: </strong>The aim of the study was to verify the usefulness of the shoe series and the association of fungal infection with positive results in the shoe series.<br /><br /><strong>METHODS: </strong>A total of 140 patients with suspected shoe contact dermatitis underwent patch testing with the standard series and shoe series; 41 underwent mycologic examination.<br /><br /><strong>RESULTS: </strong>Positive results in the shoe series were noted in 58 patients (41.4%). The most common allergens were potassium dichromate (27.2%), nickel sulfate (11.9%), Kathon CG (10.9%), and 4-tert-butylphenol formaldehyde resin (8.7%). Of the 41 patients with suspected tinea pedis, 13 (32%) had positive mycologic findings and 9 (69.2%) also had a positive response to the shoe series. Of the patients with a negative result on mycologic examination, only 10 (35.7%) had a positive result in the shoe series.<br /><br /><strong>CONCLUSION: </strong>Our study indicates that all patients with foot dermatitis should undergo patch testing with the shoe series. Positive results in the shoe series seem to be more prevalent in patients with a fungal infection."
1234362,Forcella et al. 2004,Changes in leucine transport activity in Chironomus riparius larvae after short-term exposure to potassium dichromate and fenitrothion,"The effect of sublethal concentrations of potassium dichromate and fenitrothion on sodium-leucine cotransport in brush border membrane vesicles from Chironomus riparius larvae has been investigated. Exposure to potassium dichromate and fenitrothion caused a dose- and time-dependent inhibition of leucine uptake. Transport inhibition is easily detectable at doses 100-fold lower than LD50. Kinetic experiments showed that inhibition was mainly caused by a decrease of the Vmax (680 +/- 53 vs. 382 +/- 23 and 555 +/- 27 nmol/15s/mg protein in control and exposed larvae to K2Cr2O7 and fenitrothion, respectively). Inhibition is possibly related to a variation of sodium ions permeability as evidenced by increased membrane lipid peroxidation. Appropriate control experiments ruled out that the observed differences could be due to changes in general features of membrane preparations. Transport inhibition observed in larvae exposed to potassium dichromate was accompanied by changes in ascorbate peroxidase and dehydroascorbate reductase activities, whereas those exposed to fenitrothion displayed an increase in transaminase activity. The possible value of leucine uptake as biochemical biomarker is briefly discussed. Arch. Insect Biochem. Physiol. 55:90-101, 2004.","Changes in leucine transport activity in Chironomus riparius larvae after short-term exposure to potassium dichromate and fenitrothion Abs: The effect of sublethal concentrations of potassium dichromate and fenitrothion on sodium-leucine cotransport in brush border membrane vesicles from Chironomus riparius larvae has been investigated. Exposure to potassium dichromate and fenitrothion caused a dose- and time-dependent inhibition of leucine uptake. Transport inhibition is easily detectable at doses 100-fold lower than LD50. Kinetic experiments showed that inhibition was mainly caused by a decrease of the Vmax (680 +/- 53 vs. 382 +/- 23 and 555 +/- 27 nmol/15s/mg protein in control and exposed larvae to K2Cr2O7 and fenitrothion, respectively). Inhibition is possibly related to a variation of sodium ions permeability as evidenced by increased membrane lipid peroxidation. Appropriate control experiments ruled out that the observed differences could be due to changes in general features of membrane preparations. Transport inhibition observed in larvae exposed to potassium dichromate was accompanied by changes in ascorbate peroxidase and dehydroascorbate reductase activities, whereas those exposed to fenitrothion displayed an increase in transaminase activity. The possible value of leucine uptake as biochemical biomarker is briefly discussed. Arch. Insect Biochem. Physiol. 55:90-101, 2004."
1234361,Manzo 2004,Sea urchin embryotoxicity test: proposal for a simplified bioassay,"Sea urchin embryotoxicity tests are widely used for evaluating the biological effects of contaminants in marine environments. The currently used traditional and standardized protocols are quite slow and laborious. The present work shows a modified bioassay (new embryotoxicity test; NET) in an attempt to speed up laboratory work using a limited number of fertilized eggs. Several experiments have been conducted both with a traditional bioassay and with the NET, using the same test conditions, in order to evaluate the reliability of the proposed simplified bioassay. Adult Paracentrotus lividus (Lamark) were collected from the Tyrrenian Sea (Bay of Naples) and embryos, reared in filtered seawater, were exposed to increasing potassium dichromate and copper sulfate concentrations. Then the EC(50) was calculated. The analysis of the results evidenced good repeatability. The confidence limits in all tests overlapped; moreover, data correlation analysis between the results of both tests showed a high significant accordance (chromium, R2 = 0.93, P &lt; 0.01; copper, R2 = 0.86, P &lt; 0/05). In conclusion, the NET seems to be a good alternative to the traditional tests; it could be a first step toward a new routine ecotoxicological kit for seawater.","Sea urchin embryotoxicity test: proposal for a simplified bioassay Abs: Sea urchin embryotoxicity tests are widely used for evaluating the biological effects of contaminants in marine environments. The currently used traditional and standardized protocols are quite slow and laborious. The present work shows a modified bioassay (new embryotoxicity test; NET) in an attempt to speed up laboratory work using a limited number of fertilized eggs. Several experiments have been conducted both with a traditional bioassay and with the NET, using the same test conditions, in order to evaluate the reliability of the proposed simplified bioassay. Adult Paracentrotus lividus (Lamark) were collected from the Tyrrenian Sea (Bay of Naples) and embryos, reared in filtered seawater, were exposed to increasing potassium dichromate and copper sulfate concentrations. Then the EC(50) was calculated. The analysis of the results evidenced good repeatability. The confidence limits in all tests overlapped; moreover, data correlation analysis between the results of both tests showed a high significant accordance (chromium, R2 = 0.93, P &lt; 0.01; copper, R2 = 0.86, P &lt; 0/05). In conclusion, the NET seems to be a good alternative to the traditional tests; it could be a first step toward a new routine ecotoxicological kit for seawater."
1234359,Goon and  Goh 2003,Relevance of positive patch test reactions in patients attending a dermatology tertiary referral centre,"Our purpose was to determine the proportion of relevant patch test reactions among all patch tested patients in the National Skin Centre (NSC), Singapore, from 1 January 1999 to 31 December 2000. A retrospective study was made of the patch test records of all patients patch tested in the study period. The proportion of relevant patch tests in this population was then determined. The allergens most likely to have present or past relevance were: nickel sulfate (79%), p-phenylenediamine (76%), colophonium (73%), cobalt chloride (68%) and potassium dichromate (67%). The most common allergens for each of the following relevance categories were as follows - present: p-phenylenediamine, thiuram mix, potassium dichromate; past: colophony, nickel sulfate, cobalt chloride; exposed: neomycin, gold sodium thiosulfate, fragrance mix and unknown: gold sodium thiosulfate, potassium dichromate, cobalt chloride. Evaluating relevance is difficult, and the results of relevance scoring vary widely between different groups. A consensus on the definition and standardization of the concept of relevance is needed.","Relevance of positive patch test reactions in patients attending a dermatology tertiary referral centre Abs: Our purpose was to determine the proportion of relevant patch test reactions among all patch tested patients in the National Skin Centre (NSC), Singapore, from 1 January 1999 to 31 December 2000. A retrospective study was made of the patch test records of all patients patch tested in the study period. The proportion of relevant patch tests in this population was then determined. The allergens most likely to have present or past relevance were: nickel sulfate (79%), p-phenylenediamine (76%), colophonium (73%), cobalt chloride (68%) and potassium dichromate (67%). The most common allergens for each of the following relevance categories were as follows - present: p-phenylenediamine, thiuram mix, potassium dichromate; past: colophony, nickel sulfate, cobalt chloride; exposed: neomycin, gold sodium thiosulfate, fragrance mix and unknown: gold sodium thiosulfate, potassium dichromate, cobalt chloride. Evaluating relevance is difficult, and the results of relevance scoring vary widely between different groups. A consensus on the definition and standardization of the concept of relevance is needed."
1234358,Brasch et al. 2003,Patch-test reaction patterns in patients with a predisposition to atopic dermatitis,"Patients with a predisposition to atopic dermatitis often need to be patch tested in order to detect possible contact sensitization. However, it is unknown whether immunologic or other peculiarities of atopic skin are related to altered patch-test reaction patterns. Our study was aimed at answering this question, because patch-test reaction patterns are of considerable practical importance in the reading and interpretation of patch tests. Therefore, we compared patterns of patch-test reactions in patients with a predisposition to atopic dermatitis and in control patients matched for sex, age, reason for testing and test centre. Patch-test results from 9 centres (2322 patients with a disposition to atopic dermatitis and 2126 matched controls) were evaluated retrospectively. All patients were tested with nickel sulfate, fragrance mix, potassium dichromate, lanolin alcohol, formaldehyde and mercury ammonium chloride. Patch tests applied for 1 day with readings on days 1, 2 and 3 were evaluated in order to cover the early phase of the reactions. Not unexpectedly, we found that, compared to the matched controls, patients with a predisposition to atopic dermatitis tended to have more doubtful and irritant reactions on day 1. As a new observation, it turned out that they had less reactions of crescendo pattern and more strong reactions on day 3. All these differences were slight/insignificant. A higher skin irritability in patients with a predisposition to atopic dermatitis is a likely explanation. In conclusion, standard methods for patch testing can be applied in patients with a predisposition to atopic dermatitis, but minor differences in reaction patterns should be considered.","Patch-test reaction patterns in patients with a predisposition to atopic dermatitis Abs: Patients with a predisposition to atopic dermatitis often need to be patch tested in order to detect possible contact sensitization. However, it is unknown whether immunologic or other peculiarities of atopic skin are related to altered patch-test reaction patterns. Our study was aimed at answering this question, because patch-test reaction patterns are of considerable practical importance in the reading and interpretation of patch tests. Therefore, we compared patterns of patch-test reactions in patients with a predisposition to atopic dermatitis and in control patients matched for sex, age, reason for testing and test centre. Patch-test results from 9 centres (2322 patients with a disposition to atopic dermatitis and 2126 matched controls) were evaluated retrospectively. All patients were tested with nickel sulfate, fragrance mix, potassium dichromate, lanolin alcohol, formaldehyde and mercury ammonium chloride. Patch tests applied for 1 day with readings on days 1, 2 and 3 were evaluated in order to cover the early phase of the reactions. Not unexpectedly, we found that, compared to the matched controls, patients with a predisposition to atopic dermatitis tended to have more doubtful and irritant reactions on day 1. As a new observation, it turned out that they had less reactions of crescendo pattern and more strong reactions on day 3. All these differences were slight/insignificant. A higher skin irritability in patients with a predisposition to atopic dermatitis is a likely explanation. In conclusion, standard methods for patch testing can be applied in patients with a predisposition to atopic dermatitis, but minor differences in reaction patterns should be considered."
1234357,Choi and  Roche 2004,"Effect of potassium dichromate and fenitrothion on hemoglobins of Chironomus riparius Mg. (Diptera, Chironomidae) larvae: potential biomarker of environmental monitoring","In an attempt to identify Chironomus hemoglobins as biomarkers for environmental monitoring, alterations in the hemoglobins in Chironomus riparius Mg. (Diptera: Chironomidae) larvae, exposed to potassium dichromate and fenitrothion, were investigated under laboratory conditions. The hemoglobins were evaluated in terms of their total contents by a cyanomethemoglobin procedure, individual components by electrophoresis of isoelectric focusing, and their oxidation by multi wavelength rapid-scanning spectrophotometry. The total hemoglobin contents increased at the high level of fenitrothion exposure. No variations in the individual hemoglobin component levels were found, by exposure to either fenitrothion or potassium dichromate. Whereas, the absorption spectra of the hemoglobins showed decreases in the peaks corresponding to the oxyhemoglobins by exposure to both compounds, but more sensitively by the chromium, which probably reflects the increase of the autoxidation of the oxyhemoglobins to methemoglobins by these compounds. These results suggest that autoxidation of the hemoglobins in Chironomus riparius seems to be a sensitive parameter in response to redox-active chemical exposure, and this biochemical parameter could be developed as a biomarker in environmental monitoring.","Effect of potassium dichromate and fenitrothion on hemoglobins of Chironomus riparius Mg. (Diptera, Chironomidae) larvae: potential biomarker of environmental monitoring Abs: In an attempt to identify Chironomus hemoglobins as biomarkers for environmental monitoring, alterations in the hemoglobins in Chironomus riparius Mg. (Diptera: Chironomidae) larvae, exposed to potassium dichromate and fenitrothion, were investigated under laboratory conditions. The hemoglobins were evaluated in terms of their total contents by a cyanomethemoglobin procedure, individual components by electrophoresis of isoelectric focusing, and their oxidation by multi wavelength rapid-scanning spectrophotometry. The total hemoglobin contents increased at the high level of fenitrothion exposure. No variations in the individual hemoglobin component levels were found, by exposure to either fenitrothion or potassium dichromate. Whereas, the absorption spectra of the hemoglobins showed decreases in the peaks corresponding to the oxyhemoglobins by exposure to both compounds, but more sensitively by the chromium, which probably reflects the increase of the autoxidation of the oxyhemoglobins to methemoglobins by these compounds. These results suggest that autoxidation of the hemoglobins in Chironomus riparius seems to be a sensitive parameter in response to redox-active chemical exposure, and this biochemical parameter could be developed as a biomarker in environmental monitoring."
1234356,Rizki et al. 2004,Genotoxicity modulation by cadmium treatment: studies in the Drosophila wing spot test,"The genotoxic activity of cadmium chloride (CC) has been evaluated in the somatic mutation and recombination test (SMART) in Drosophila melanogaster. In addition, its possible modulating effect on the genotoxicity of two known mutagenic agents, potassium dichromate (PDC) and ethyl methanesulfonate (EMS), was investigated. Three different types of combined treatments of CC with the two genotoxins were performed: pretreatment, cotreatment, and posttreatment. The SMART assay is based on the principle that loss of heterozygosity for the recessive markers, multiple wing hairs (mwh) and flare-3 (flr(3)), leads to the formation of mutant clones in the imaginal disks of larvae, which are expressed as mutant spots on the wings of adult flies. Thus, after adult emergence, the wings of the adult flies were scored for the presence of single and/or twin spots. Our results show that CC alone was not effective in increasing the frequency of any of the three categories of spots (small, large, and twin). In the cotreatment experiments, CC increased the genotoxicity of PDC but it decreased the genotoxicity of EMS. No effects of CC were observed in the pretreatment or posttreatment experiments; however, only low concentrations of CC, PDC, and EMS were tested in the pretreatment assays due to the high toxicity of the treatment. Although our results with PDC are consistent with the hypothesis that cadmium can interfere with repair mechanisms, the EMS data suggest that other modulating mechanisms are also involved in the genotoxicity of this metal.","Genotoxicity modulation by cadmium treatment: studies in the Drosophila wing spot test Abs: The genotoxic activity of cadmium chloride (CC) has been evaluated in the somatic mutation and recombination test (SMART) in Drosophila melanogaster. In addition, its possible modulating effect on the genotoxicity of two known mutagenic agents, potassium dichromate (PDC) and ethyl methanesulfonate (EMS), was investigated. Three different types of combined treatments of CC with the two genotoxins were performed: pretreatment, cotreatment, and posttreatment. The SMART assay is based on the principle that loss of heterozygosity for the recessive markers, multiple wing hairs (mwh) and flare-3 (flr(3)), leads to the formation of mutant clones in the imaginal disks of larvae, which are expressed as mutant spots on the wings of adult flies. Thus, after adult emergence, the wings of the adult flies were scored for the presence of single and/or twin spots. Our results show that CC alone was not effective in increasing the frequency of any of the three categories of spots (small, large, and twin). In the cotreatment experiments, CC increased the genotoxicity of PDC but it decreased the genotoxicity of EMS. No effects of CC were observed in the pretreatment or posttreatment experiments; however, only low concentrations of CC, PDC, and EMS were tested in the pretreatment assays due to the high toxicity of the treatment. Although our results with PDC are consistent with the hypothesis that cadmium can interfere with repair mechanisms, the EMS data suggest that other modulating mechanisms are also involved in the genotoxicity of this metal."
1234355,Li et al. 2004,Micronuclei induced by municipal landfill leachate in mouse bone marrow cells in vivo,"The induction of micronuclei (MN) in polychromatic erythrocytes (PCE) of mouse bone marrow by municipal landfill leachate was studied in vivo. Results showed that mouse exposure via drinking water containing various concentrations of leachate caused a significant increase of MN frequencies in a concentration (Chemical oxygen demand measured with potassium dichromate oxidation, COD(Cr))-dependent manner. MN induction in female and male mice was different at higher concentrations. This implies that leachate is a genotoxic agent in mammalian cells and that exposure to leachate in an aquatic environment may pose a potential genotoxic risk to human beings.","Micronuclei induced by municipal landfill leachate in mouse bone marrow cells in vivo Abs: The induction of micronuclei (MN) in polychromatic erythrocytes (PCE) of mouse bone marrow by municipal landfill leachate was studied in vivo. Results showed that mouse exposure via drinking water containing various concentrations of leachate caused a significant increase of MN frequencies in a concentration (Chemical oxygen demand measured with potassium dichromate oxidation, COD(Cr))-dependent manner. MN induction in female and male mice was different at higher concentrations. This implies that leachate is a genotoxic agent in mammalian cells and that exposure to leachate in an aquatic environment may pose a potential genotoxic risk to human beings."
1234353,Sang and  Li 2004,Genotoxicity of municipal landfill leachate on root tips of Vicia faba,"The genotoxicity of municipal landfill leachate was studied using the Vicia faba root-tip cytogenetic bioassay. Results show that landfill leachates collected in different seasons decreased the mitotic index (MI) and caused significant increases of micronucleus (MN) frequencies and anaphase aberration (AA) frequencies in a concentration-dependent manner (concentration expressed as 'chemical oxygen demand' measured by the method of potassium dichromate oxidation (COD(Cr))). In addition, a seasonal difference in genotoxicity induced by leachate was observed. The results confirm that leachate is a genotoxic agent in plant cells and imply that exposure to leachate in the aquatic environment may pose a potential genotoxic risk to organisms. The results also show that the V. faba cytogenetic bioassay is efficient, simple and reproducible in genotoxicity studies of leachate, and that there is a correlation between the genotoxicity and the chemical measurement (COD(Cr)) of leachate.","Genotoxicity of municipal landfill leachate on root tips of Vicia faba Abs: The genotoxicity of municipal landfill leachate was studied using the Vicia faba root-tip cytogenetic bioassay. Results show that landfill leachates collected in different seasons decreased the mitotic index (MI) and caused significant increases of micronucleus (MN) frequencies and anaphase aberration (AA) frequencies in a concentration-dependent manner (concentration expressed as 'chemical oxygen demand' measured by the method of potassium dichromate oxidation (COD(Cr))). In addition, a seasonal difference in genotoxicity induced by leachate was observed. The results confirm that leachate is a genotoxic agent in plant cells and imply that exposure to leachate in the aquatic environment may pose a potential genotoxic risk to organisms. The results also show that the V. faba cytogenetic bioassay is efficient, simple and reproducible in genotoxicity studies of leachate, and that there is a correlation between the genotoxicity and the chemical measurement (COD(Cr)) of leachate."
1234352,Jain et al. 2004,Role of contact allergens in pompholyx,"Fifty patients of both sexes with clinically suspected pompholyx were patch tested with the Indian Standard Patch Test Battery approved by the Contact &amp; Occupational Dermatosis Forum of India (CODFI). Most of these patients were young adults between 20-39 years of age with a mean age of 30 years. The mean duration of symptoms was 4 years. The occupational profile of the patients included students (20%), housewives (16%), housewives engaged in farming (12%), labourers (12%), farmers (12%) and paramedical workers (6%). The miscellaneous group, including salesmen, teachers and photographers, accounted for the remaining 22%. The clinical patterns of presentation of pompholyx included cheiropompholyx (60%), cheiropompholyx and podopompholyx (36%) and podopompholyx alone (4%). Patch test analysis of these patients revealed that, out of the 50 subjects tested, 20 (40%) reacted to one or more allergens. Nickel sulphate was the commonest offending allergen (14%) followed by potassium dichromate and phenylene diamine and nitrofurazone (8% each), fragrance mix (6%) and cobalt chloride (4%), in descending order of frequency. Hence, patch testing may be considered for all patients with recurrent episodes of pompholyx as allergic contact dermatitis may be relatively common in such patients and the avoidance of offending allergens may be of substantial benefit to these patients.","Role of contact allergens in pompholyx Abs: Fifty patients of both sexes with clinically suspected pompholyx were patch tested with the Indian Standard Patch Test Battery approved by the Contact &amp; Occupational Dermatosis Forum of India (CODFI). Most of these patients were young adults between 20-39 years of age with a mean age of 30 years. The mean duration of symptoms was 4 years. The occupational profile of the patients included students (20%), housewives (16%), housewives engaged in farming (12%), labourers (12%), farmers (12%) and paramedical workers (6%). The miscellaneous group, including salesmen, teachers and photographers, accounted for the remaining 22%. The clinical patterns of presentation of pompholyx included cheiropompholyx (60%), cheiropompholyx and podopompholyx (36%) and podopompholyx alone (4%). Patch test analysis of these patients revealed that, out of the 50 subjects tested, 20 (40%) reacted to one or more allergens. Nickel sulphate was the commonest offending allergen (14%) followed by potassium dichromate and phenylene diamine and nitrofurazone (8% each), fragrance mix (6%) and cobalt chloride (4%), in descending order of frequency. Hence, patch testing may be considered for all patients with recurrent episodes of pompholyx as allergic contact dermatitis may be relatively common in such patients and the avoidance of offending allergens may be of substantial benefit to these patients."
1234351,Ale and  Maibach 2004,Reproducibility of patch test results: a concurrent right-versus-left study using TRUE Test,"Wide variations in the reproducibility rate of positive patch test responses have been reported. We hypothesized that a major source of non-reproducibility resides in the methodological pitfalls of routine patch testing. Simultaneous duplicate patch testing on opposite sides of the upper back was performed on 500 consecutive patients, using the TRUE Test system consisting of 2 panels, each one containing 12 standard allergens. A rigorous methodological design was applied and relevance was assessed for all discordant patch test reactions. A total of 435 positive patch test reactions were observed either on one or both sides in 289 patients (58.8%). Of these, 22 (5%) were discordant, i.e. interpreted as positive allergic on one side whilst negative or doubtful on the opposite side. The allergens responsible for discordant reactions were nickel sulfate (4 patients), cobalt chloride (3), lanolin alcohol (3), fragrance mix (2), carba mix (2), thiuram mix (2), colophonium (1), potassium dichromate (1), p-phenylenediamine (1), formaldehyde (1), balsam of Peru (Myroxylon pereirae resin) (1) and thimerosal (1). Of the 19 (4%) patients with discordant patch test reactions, the allergen was deemed to be of definite present or past relevance in 9 patients (1.8% of the total and 3.1% of all patients with positive patch test reactions) and of possible relevance in a further 2 patients. These data suggest that patch testing is a reasonably reproducible procedure as long as methodological error is minimized.","Reproducibility of patch test results: a concurrent right-versus-left study using TRUE Test Abs: Wide variations in the reproducibility rate of positive patch test responses have been reported. We hypothesized that a major source of non-reproducibility resides in the methodological pitfalls of routine patch testing. Simultaneous duplicate patch testing on opposite sides of the upper back was performed on 500 consecutive patients, using the TRUE Test system consisting of 2 panels, each one containing 12 standard allergens. A rigorous methodological design was applied and relevance was assessed for all discordant patch test reactions. A total of 435 positive patch test reactions were observed either on one or both sides in 289 patients (58.8%). Of these, 22 (5%) were discordant, i.e. interpreted as positive allergic on one side whilst negative or doubtful on the opposite side. The allergens responsible for discordant reactions were nickel sulfate (4 patients), cobalt chloride (3), lanolin alcohol (3), fragrance mix (2), carba mix (2), thiuram mix (2), colophonium (1), potassium dichromate (1), p-phenylenediamine (1), formaldehyde (1), balsam of Peru (Myroxylon pereirae resin) (1) and thimerosal (1). Of the 19 (4%) patients with discordant patch test reactions, the allergen was deemed to be of definite present or past relevance in 9 patients (1.8% of the total and 3.1% of all patients with positive patch test reactions) and of possible relevance in a further 2 patients. These data suggest that patch testing is a reasonably reproducible procedure as long as methodological error is minimized."
1234350,Hugonnot et al. 2004,Kinetic control of surface patterning by laser-induced photochemical deposition in liquid solutions. II. Experimental investigations,"We experimentally analyze the real-time formation of periodic surface patterning resulting from laser-driven photochemical deposition in liquid solutions. Using photochemical deposition of chromium hydroxide layers driven by a continuous Ar+ laser wave in a potassium chromate solution, we analyze the kinetic formation of three different types of patterning: dot array, periodic line writing, and holographic grating formed by interfering beams. Results are also presented for both flat and curved substrates. In each case, the deposit growth laws are measured and they show the emergence of scaling regimes that are predicted by our model [Phys. Rev. E 69, 051605 (2004)]]. Data taken from literature are also confronted to the model. The observed agreement suggests that a unified picture of the processes involved for photodeposition driven by a one-photon absorption can be devised, whatever the initial photosensitive medium is. This kinetic control of photodeposition, associated to the versatility in monitoring the geometry of laser/medium interaction and the flexibility in deposited materials by various photochemical reactions, offers a valuable level of development in substrate patterning for lithographic or holographic applications.","Kinetic control of surface patterning by laser-induced photochemical deposition in liquid solutions. II. Experimental investigations Abs: We experimentally analyze the real-time formation of periodic surface patterning resulting from laser-driven photochemical deposition in liquid solutions. Using photochemical deposition of chromium hydroxide layers driven by a continuous Ar+ laser wave in a potassium chromate solution, we analyze the kinetic formation of three different types of patterning: dot array, periodic line writing, and holographic grating formed by interfering beams. Results are also presented for both flat and curved substrates. In each case, the deposit growth laws are measured and they show the emergence of scaling regimes that are predicted by our model [Phys. Rev. E 69, 051605 (2004)]]. Data taken from literature are also confronted to the model. The observed agreement suggests that a unified picture of the processes involved for photodeposition driven by a one-photon absorption can be devised, whatever the initial photosensitive medium is. This kinetic control of photodeposition, associated to the versatility in monitoring the geometry of laser/medium interaction and the flexibility in deposited materials by various photochemical reactions, offers a valuable level of development in substrate patterning for lithographic or holographic applications."
1234349,White and  Jahnke 2004,Removing UV-A and UV-C radiation from UV-B fluorescent lamp emissions. Differences in the inhibition of photosynthesis in the marine alga Dunaliella tertiolecta using chromate versus cellulose acetate-polyester filters,"Ultraviolet-B (UV-B; 280-320 nm)-emitting lamps unavoidably emit ultraviolet-A (UV-A; 320-400 nm) and ultraviolet-C (UV-C; &lt;280 nm) radiation. Short-wavelength-blocking filters are generally used to limit the wave bands of UV under investigation. The widespread use of such filters means that all exposures to UV-B radiation will have a significant UV-A component. Therefore, the physiological effects unique to UV-B exposure are difficult to clearly isolate. This study presents a method to remove the UV-A and UV-C &quot;contamination&quot; using a liquid potassium chromate (K(2)CrO(4)) filter, thus allowing more direct assessment of the effects of UV-B exposure. Cultures of the green marine alga Dunaliella tertiolecta were grown in the absence of UV radiation. Sunlamps supplied the UV radiation for a 24 h exposure (solar radiation was not used in this study). The UV radiation was filtered either by the standard method (i.e. cellulose acetate (CA) with polyester = Mylar controls) or by a liquid filter of potassium chromate. Photosynthetic responses were compared. Major decreases in the ratio of variable to maximal fluorescence in dark-adapted cells and photosynthetic capacity were observed in CA-filtered cultures, whereas no change was observed in cells exposed to the same UV-B flux with the UV-A removed by K(2)CrO(4). The use of a CA filter with a Mylar control does not link results unequivocally to UV-B radiation. Such results should be interpreted with caution.","Removing UV-A and UV-C radiation from UV-B fluorescent lamp emissions. Differences in the inhibition of photosynthesis in the marine alga Dunaliella tertiolecta using chromate versus cellulose acetate-polyester filters Abs: Ultraviolet-B (UV-B; 280-320 nm)-emitting lamps unavoidably emit ultraviolet-A (UV-A; 320-400 nm) and ultraviolet-C (UV-C; &lt;280 nm) radiation. Short-wavelength-blocking filters are generally used to limit the wave bands of UV under investigation. The widespread use of such filters means that all exposures to UV-B radiation will have a significant UV-A component. Therefore, the physiological effects unique to UV-B exposure are difficult to clearly isolate. This study presents a method to remove the UV-A and UV-C &quot;contamination&quot; using a liquid potassium chromate (K(2)CrO(4)) filter, thus allowing more direct assessment of the effects of UV-B exposure. Cultures of the green marine alga Dunaliella tertiolecta were grown in the absence of UV radiation. Sunlamps supplied the UV radiation for a 24 h exposure (solar radiation was not used in this study). The UV radiation was filtered either by the standard method (i.e. cellulose acetate (CA) with polyester = Mylar controls) or by a liquid filter of potassium chromate. Photosynthetic responses were compared. Major decreases in the ratio of variable to maximal fluorescence in dark-adapted cells and photosynthetic capacity were observed in CA-filtered cultures, whereas no change was observed in cells exposed to the same UV-B flux with the UV-A removed by K(2)CrO(4). The use of a CA filter with a Mylar control does not link results unequivocally to UV-B radiation. Such results should be interpreted with caution."
1234348,Butkauskas and  Sruoga 2004,Effect of lead and chromium on reproductive success of Japanese quail,"An experimental model based on application of Japanese quail (Coturnix coturnix japonica) lines with high (H) and low (L) concentrations of plasma lactate was designed in order to investigate the effects of lead and chromium on embryonic development and reproductive success of experimental groups representing different genotypes. During the first stage of the trial, mature males from quail lines H and L (marked as generation T) were fed subchronically for 12 weeks with lead as Pb(NO(3))(2) and chromium as K(2)Cr(2)O(7) (dosage 0.8 and 0.142 g/kg, respectively, in the feed). In addition, a binary mixture of both lead and chromium was administered to the third group of males. The control group consisted of untreated birds. After mating with untreated females (8 female x 5 male in each group), progeny with four genotypes were obtained. The chicks were marked as generation F1 and used in the second stage of the trial. The data obtained show that heavy metals decreased the hatchability of sexually mature quail males: chromium (14%), lead (19%), and binary lead-chromium mixture (28%). Early embryonic mortality increased as much as 2-3 times. Single lead and binary lead-chromium additions decreased fertility after treating Japanese quail during the development of sexual maturity: lead increased the number of unfertile eggs up to 30% (twofold), binary lead and chromium, up to 50% (more than threefold) relative to untreated controls. There was no effect of chromium alone on fertility. In general, hatchability, fertility, embryonic mortality and reproductive success of Japanese quail were dependent on age, sex, genotypes, and on single or binary treatment with the inorganic salts of lead and chromium.","Effect of lead and chromium on reproductive success of Japanese quail Abs: An experimental model based on application of Japanese quail (Coturnix coturnix japonica) lines with high (H) and low (L) concentrations of plasma lactate was designed in order to investigate the effects of lead and chromium on embryonic development and reproductive success of experimental groups representing different genotypes. During the first stage of the trial, mature males from quail lines H and L (marked as generation T) were fed subchronically for 12 weeks with lead as Pb(NO(3))(2) and chromium as K(2)Cr(2)O(7) (dosage 0.8 and 0.142 g/kg, respectively, in the feed). In addition, a binary mixture of both lead and chromium was administered to the third group of males. The control group consisted of untreated birds. After mating with untreated females (8 female x 5 male in each group), progeny with four genotypes were obtained. The chicks were marked as generation F1 and used in the second stage of the trial. The data obtained show that heavy metals decreased the hatchability of sexually mature quail males: chromium (14%), lead (19%), and binary lead-chromium mixture (28%). Early embryonic mortality increased as much as 2-3 times. Single lead and binary lead-chromium additions decreased fertility after treating Japanese quail during the development of sexual maturity: lead increased the number of unfertile eggs up to 30% (twofold), binary lead and chromium, up to 50% (more than threefold) relative to untreated controls. There was no effect of chromium alone on fertility. In general, hatchability, fertility, embryonic mortality and reproductive success of Japanese quail were dependent on age, sex, genotypes, and on single or binary treatment with the inorganic salts of lead and chromium."
1234347,Akhtar et al. 2004,Patch test for the detection of contact allergens,"Patch Test was done in 340 suspected allergic contact dermatitis patients having different ages of both sexes during the period of January 2000 to December 2003 in the department of Dermatology and Venerology, Bangabandhu Sheikh Mujib Medical University (BSMMU), Dhaka. Of these 340 cases 145 (42.65%) were male and 195 (57.35%) were female. Among these 340 cases, 250 (73.53%) cases were tested with international standard series allergen (ISS) and 90 (26.47%) cases with cosmetic series allergen (CSS), of which patch test was positive in 125 (50%) cases and 65 (72.22%) cases respectively. The 125 positive cases with ISS consisted of 56% male and 44% female. In 65 CSS positive cases 90.77% were female and 9.23% were male. Highest incidence of positive patch test was found in 61.54% cases in the age group of 30-39 years in ISS and 71.43% cases in the age group of 20-29 yrs in CSS. In ISS--Potassium Dichromate (19.2%), Fragrance mix (17.6%), Nickel Sulphate (15.2%) and PPD (11.2%) were found to be the common allergen and in CSS--Octyl Gallate (27.69%), Getrimide (18.92%), Balsum of Peru (15.38%), Thiomersal (12.31%) were found to be the common allergens.","Patch test for the detection of contact allergens Abs: Patch Test was done in 340 suspected allergic contact dermatitis patients having different ages of both sexes during the period of January 2000 to December 2003 in the department of Dermatology and Venerology, Bangabandhu Sheikh Mujib Medical University (BSMMU), Dhaka. Of these 340 cases 145 (42.65%) were male and 195 (57.35%) were female. Among these 340 cases, 250 (73.53%) cases were tested with international standard series allergen (ISS) and 90 (26.47%) cases with cosmetic series allergen (CSS), of which patch test was positive in 125 (50%) cases and 65 (72.22%) cases respectively. The 125 positive cases with ISS consisted of 56% male and 44% female. In 65 CSS positive cases 90.77% were female and 9.23% were male. Highest incidence of positive patch test was found in 61.54% cases in the age group of 30-39 years in ISS and 71.43% cases in the age group of 20-29 yrs in CSS. In ISS--Potassium Dichromate (19.2%), Fragrance mix (17.6%), Nickel Sulphate (15.2%) and PPD (11.2%) were found to be the common allergen and in CSS--Octyl Gallate (27.69%), Getrimide (18.92%), Balsum of Peru (15.38%), Thiomersal (12.31%) were found to be the common allergens."
1234346,Schecter et al. 2004,The use of potassium dichromate and ethyl alcohol as blood preservatives for analysis of organochlorine contaminants,"The &quot;gold standard&quot; for preserving and shipping of human tissue samples for analysis of organochlorine contaminants is freezing. This method can be difficult, costly if using heavy dry ice for shipping, and often unfeasible, especially in less developed countries where electricity and dry ice are frequently rare or absent. Therefore, it is essential that more convenient and practical methods for preservation of blood samples are found. As an alternative to freezing, there have been studies employing potassium dichromate as a preservative for human or cow's milk or ethyl alcohol preservation of blood for dioxin analysis. In this study, four methods were compared to investigate the effectiveness of ethyl alcohol and potassium dichromate as blood preservatives for analysis of dioxins, dibenzofuran, and polychlorinated biphenyl (PCB) congeners. Samples of whole blood from a Dallas, Texas hospital were collected and pooled. Freezing, ethyl alcohol in two concentrations (20% and 40% per volume of sample), and potassium dichromate were used for blood preservation. The blood samples containing potassium dichromate or ethyl alcohol were stored and sent to ERGO laboratory for dioxin analysis and comparison with results from the frozen sample, which was kept frozen at all times until analyzed. This study suggests that potassium dichromate is a suitable alternative to freezing for preservation of whole blood for dioxin, dibenzofuran, and PCB measurements when either lipid or wet weight based results are reported. Potassium dichromate tablets were very easy and convenient to use--two 100 mg tablets (with a dichromate content of about 33 mg each) were added to each bottle containing 65 ml of blood. However, ethyl alcohol at 20% and 40% concentration under the conditions of this pilot study and the analytical method employed did not appear to provide satisfactory preservation when lipid based results are given or when the fat content has to be determined (wet or whole weight). Further research with a larger number of samples, inclusion also of other groups of persistent organic pollutants such as organochlorine pesticides or brominated flame retardants, a longer duration of storage time, and at temperatures greater than US or German room temperature is indicated in order to recommend the routine use of potassium dichromate as preservative for whole blood intended for dioxin, dibenzofuran, and PCB analysis.","The use of potassium dichromate and ethyl alcohol as blood preservatives for analysis of organochlorine contaminants Abs: The &quot;gold standard&quot; for preserving and shipping of human tissue samples for analysis of organochlorine contaminants is freezing. This method can be difficult, costly if using heavy dry ice for shipping, and often unfeasible, especially in less developed countries where electricity and dry ice are frequently rare or absent. Therefore, it is essential that more convenient and practical methods for preservation of blood samples are found. As an alternative to freezing, there have been studies employing potassium dichromate as a preservative for human or cow's milk or ethyl alcohol preservation of blood for dioxin analysis. In this study, four methods were compared to investigate the effectiveness of ethyl alcohol and potassium dichromate as blood preservatives for analysis of dioxins, dibenzofuran, and polychlorinated biphenyl (PCB) congeners. Samples of whole blood from a Dallas, Texas hospital were collected and pooled. Freezing, ethyl alcohol in two concentrations (20% and 40% per volume of sample), and potassium dichromate were used for blood preservation. The blood samples containing potassium dichromate or ethyl alcohol were stored and sent to ERGO laboratory for dioxin analysis and comparison with results from the frozen sample, which was kept frozen at all times until analyzed. This study suggests that potassium dichromate is a suitable alternative to freezing for preservation of whole blood for dioxin, dibenzofuran, and PCB measurements when either lipid or wet weight based results are reported. Potassium dichromate tablets were very easy and convenient to use--two 100 mg tablets (with a dichromate content of about 33 mg each) were added to each bottle containing 65 ml of blood. However, ethyl alcohol at 20% and 40% concentration under the conditions of this pilot study and the analytical method employed did not appear to provide satisfactory preservation when lipid based results are given or when the fat content has to be determined (wet or whole weight). Further research with a larger number of samples, inclusion also of other groups of persistent organic pollutants such as organochlorine pesticides or brominated flame retardants, a longer duration of storage time, and at temperatures greater than US or German room temperature is indicated in order to recommend the routine use of potassium dichromate as preservative for whole blood intended for dioxin, dibenzofuran, and PCB analysis."
1234345,Herbst et al. 2004,Allergic and non-allergic periorbital dermatitis: patch test results of the Information Network of the Departments of Dermatology during a 5-year period,"Periorbital dermatitis is common and can be due to the external use of ophthalmic drugs. We evaluated patch test results of the Information Network of the Departments of Dermatology. During a 5-year period (1995-99), of a total 49,256 patch-tested patients, 1053 (2.1%) were eventually diagnosed as allergic periorbital contact dermatitis (APD) and 588 (1.2%) as non-allergic periorbital dermatitis (NAPD). Patient characteristics between APD, NAPD and other cases (OCs) differed with respect to sex (19.7% male in both periorbital groups versus 36.3% in OCs), atopic dermatitis (10.4% in APD versus 60.2% in NAPD versus 16.9% in OCs) and age, APD being substantially more often (68.2%) aged 40 and above than NAPD (52.6%). Several of the top allergens in OCs [such as fragrance mix, Myroxylon pereirae resin (balsam of Peru), lanolin alcohol and potassium dichromate] caused significantly fewer positive test reactions in both periorbital groups. In contrast, thimerosal, phenylmercuric acetate, sodium disulfite, gentamicin sulfate, phenylephrine hydrochloride and benzalkonium chloride tested positively significantly more often in APD but not in NAPD, verifying them as true ophthalmic allergens. Finally, in 42 cases (4%) of APD patients, additional allergens were identified by testing of the patients' own substances (mostly beta-blockers, oxybuprocaine and dexpanthenol), supporting the necessity of testing with ophthalmic drugs as is where individual substances are not readily available.","Allergic and non-allergic periorbital dermatitis: patch test results of the Information Network of the Departments of Dermatology during a 5-year period Abs: Periorbital dermatitis is common and can be due to the external use of ophthalmic drugs. We evaluated patch test results of the Information Network of the Departments of Dermatology. During a 5-year period (1995-99), of a total 49,256 patch-tested patients, 1053 (2.1%) were eventually diagnosed as allergic periorbital contact dermatitis (APD) and 588 (1.2%) as non-allergic periorbital dermatitis (NAPD). Patient characteristics between APD, NAPD and other cases (OCs) differed with respect to sex (19.7% male in both periorbital groups versus 36.3% in OCs), atopic dermatitis (10.4% in APD versus 60.2% in NAPD versus 16.9% in OCs) and age, APD being substantially more often (68.2%) aged 40 and above than NAPD (52.6%). Several of the top allergens in OCs [such as fragrance mix, Myroxylon pereirae resin (balsam of Peru), lanolin alcohol and potassium dichromate] caused significantly fewer positive test reactions in both periorbital groups. In contrast, thimerosal, phenylmercuric acetate, sodium disulfite, gentamicin sulfate, phenylephrine hydrochloride and benzalkonium chloride tested positively significantly more often in APD but not in NAPD, verifying them as true ophthalmic allergens. Finally, in 42 cases (4%) of APD patients, additional allergens were identified by testing of the patients' own substances (mostly beta-blockers, oxybuprocaine and dexpanthenol), supporting the necessity of testing with ophthalmic drugs as is where individual substances are not readily available."
1234344,Perez et al. 2004,Beneficial effect of retinoic acid on the outcome of experimental acute renal failure,"<strong>BACKGROUND: </strong>Retinoic acid (RA) exerts beneficial effects on vascular remodelling and experimental nephritis, and plays a role in kidney development. Pathological changes caused by acute renal failure (ARF) result in high mortality. We determined whether RA ameliorates ARF-induced pathology caused by potassium dichromate (PD).<br /><br /><strong>METHODS: </strong>Adult Wistar female rats (210-250 g) were randomly allocated to four groups: (i) an ARF group that received PD [15 mg/kg body weight (bw), single dose subcutaneously]; (ii) a group that received PD plus RA (1 mg/kg bw) beginning at 5 days before PD and that continued for 14 additional days; (iii) a group that received PD plus thyroxine (T(4); 8 micro g/100 g bw) with RA; and (iv) a group that received only the vehicle for PD (saline solution). We evaluated functional, biochemical and morphological characteristics of the kidneys.<br /><br /><strong>RESULTS: </strong>PD-induced alterations in serum creatinine, creatinine clearance (C(cr)) and fractional excretion of sodium (FeNa) were less severe when rats received RA. PD increased lipoperoxidation and this alteration was partially blocked by RA. Animals undergoing ARF showed severe histological injury (brush border loss, acidophilia, oedema, pyknosis, karyorhexis, cell detachment and disruption of the basement membrane). These alterations were less severe in RA-treated rats, indicating a protective effect on functional and morphological alterations. Alterations in urinary sediment were reduced by RA. The simultaneous administration of T(4) with RA did not produce additional protection.<br /><br /><strong>CONCLUSION: </strong>RA exerted beneficial effects on the duration and severity of renal damage induced by PD in a model of renal failure resembling ARF in humans. The protective effect of RA may be mediated by diminished lipoperoxidative damage.","Beneficial effect of retinoic acid on the outcome of experimental acute renal failure Abs: <strong>BACKGROUND: </strong>Retinoic acid (RA) exerts beneficial effects on vascular remodelling and experimental nephritis, and plays a role in kidney development. Pathological changes caused by acute renal failure (ARF) result in high mortality. We determined whether RA ameliorates ARF-induced pathology caused by potassium dichromate (PD).<br /><br /><strong>METHODS: </strong>Adult Wistar female rats (210-250 g) were randomly allocated to four groups: (i) an ARF group that received PD [15 mg/kg body weight (bw), single dose subcutaneously]; (ii) a group that received PD plus RA (1 mg/kg bw) beginning at 5 days before PD and that continued for 14 additional days; (iii) a group that received PD plus thyroxine (T(4); 8 micro g/100 g bw) with RA; and (iv) a group that received only the vehicle for PD (saline solution). We evaluated functional, biochemical and morphological characteristics of the kidneys.<br /><br /><strong>RESULTS: </strong>PD-induced alterations in serum creatinine, creatinine clearance (C(cr)) and fractional excretion of sodium (FeNa) were less severe when rats received RA. PD increased lipoperoxidation and this alteration was partially blocked by RA. Animals undergoing ARF showed severe histological injury (brush border loss, acidophilia, oedema, pyknosis, karyorhexis, cell detachment and disruption of the basement membrane). These alterations were less severe in RA-treated rats, indicating a protective effect on functional and morphological alterations. Alterations in urinary sediment were reduced by RA. The simultaneous administration of T(4) with RA did not produce additional protection.<br /><br /><strong>CONCLUSION: </strong>RA exerted beneficial effects on the duration and severity of renal damage induced by PD in a model of renal failure resembling ARF in humans. The protective effect of RA may be mediated by diminished lipoperoxidative damage."
1234343,Lazarov 2004,Textile dermatitis in patients with contact sensitization in Israel: a 4-year prospective study,"<strong>BACKGROUND: </strong>The exact incidence of textile dermatitis is unknown because of the lack of controlled epidemiological studies. Nevertheless, the increasing frequency of contact dermatitis to clothing has been demonstrated, thus indicating the importance of further investigations in this field.<br /><br /><strong>OBJECTIVE: </strong>To analyse the results from a 4-year prospective study of the clinical and aetiological features of contact dermatitis to textiles in Israel. We also aimed to assess the frequency and relevance of sensitization to textile dyes and resins in these patients.<br /><br /><strong>METHODS: </strong>Six hundred and forty-four patients (441 female and 203 male), referred for the investigation of contact dermatitis, and suspected of having textile allergic contact dermatitis (ACD), were studied. All patients were patch tested with the standard series (TRUE Tests), textile colour and finish series (TCFS) clothing extracts and pieces of garment in some cases. Readings were performed on days 2, 3 and in many patients also on day 7.<br /><br /><strong>RESULTS: </strong>Eighty-three patients (12.9%) had an allergic reactions to a dye and/or resin allergen. Of them, 43 (51.8%) had positive patch tests to the textile dye allergens, 28 (33.7%) to the formaldehyde and textile finish resins and 12 (14.4%) to allergens from both groups. The highest incidence of sensitization from the dye group allergens was due to Disperse Blue (DB) 124 (30.6%), DB 106 (27.0%) and DB 85 (8.1%) and from the resin group to melamine formaldehyde and ethyleneurea melamine formaldehyde (20.7% each) and urea formaldehyde (18.3%). Present relevance of the patch tests was found in 81.4% of the cases. Concomitant sensitization with allergens from the standard series included nickel sulphate, potassium dichromate, formaldehyde, rubber additives and others. Although chronic dermatitis was the typical clinical presentation, less frequent forms such as purpuric, hyperpigmented and papulopustular lesions and atypical forms such as erythema multiforme-like, nummular-like lesions, lichenification and erythrodermia were observed in 24.4% of the cases. The atypical manifestations were provoked by sensitization to dye allergens and never to resins. Along with the typical distribution in areas of friction on the trunk and extremities, less frequent areas including the hands, face, genital area and the soles were affected too.<br /><br /><strong>CONCLUSIONS: </strong>In view of the increasing frequency of contact dermatitis to clothing, the clinical assessment should include awareness of the classical as well as the unusual and atypical clinical forms and locations of ACD to textiles, for they are not infrequent. Although dyes and among them DB 106 and DB 124 are the most frequent allergens inducing textile dermatitis, concomitant testing with allergens from the textile dyes and resin groups is recommended when investigating patients with textile dermatitis.","Textile dermatitis in patients with contact sensitization in Israel: a 4-year prospective study Abs: <strong>BACKGROUND: </strong>The exact incidence of textile dermatitis is unknown because of the lack of controlled epidemiological studies. Nevertheless, the increasing frequency of contact dermatitis to clothing has been demonstrated, thus indicating the importance of further investigations in this field.<br /><br /><strong>OBJECTIVE: </strong>To analyse the results from a 4-year prospective study of the clinical and aetiological features of contact dermatitis to textiles in Israel. We also aimed to assess the frequency and relevance of sensitization to textile dyes and resins in these patients.<br /><br /><strong>METHODS: </strong>Six hundred and forty-four patients (441 female and 203 male), referred for the investigation of contact dermatitis, and suspected of having textile allergic contact dermatitis (ACD), were studied. All patients were patch tested with the standard series (TRUE Tests), textile colour and finish series (TCFS) clothing extracts and pieces of garment in some cases. Readings were performed on days 2, 3 and in many patients also on day 7.<br /><br /><strong>RESULTS: </strong>Eighty-three patients (12.9%) had an allergic reactions to a dye and/or resin allergen. Of them, 43 (51.8%) had positive patch tests to the textile dye allergens, 28 (33.7%) to the formaldehyde and textile finish resins and 12 (14.4%) to allergens from both groups. The highest incidence of sensitization from the dye group allergens was due to Disperse Blue (DB) 124 (30.6%), DB 106 (27.0%) and DB 85 (8.1%) and from the resin group to melamine formaldehyde and ethyleneurea melamine formaldehyde (20.7% each) and urea formaldehyde (18.3%). Present relevance of the patch tests was found in 81.4% of the cases. Concomitant sensitization with allergens from the standard series included nickel sulphate, potassium dichromate, formaldehyde, rubber additives and others. Although chronic dermatitis was the typical clinical presentation, less frequent forms such as purpuric, hyperpigmented and papulopustular lesions and atypical forms such as erythema multiforme-like, nummular-like lesions, lichenification and erythrodermia were observed in 24.4% of the cases. The atypical manifestations were provoked by sensitization to dye allergens and never to resins. Along with the typical distribution in areas of friction on the trunk and extremities, less frequent areas including the hands, face, genital area and the soles were affected too.<br /><br /><strong>CONCLUSIONS: </strong>In view of the increasing frequency of contact dermatitis to clothing, the clinical assessment should include awareness of the classical as well as the unusual and atypical clinical forms and locations of ACD to textiles, for they are not infrequent. Although dyes and among them DB 106 and DB 124 are the most frequent allergens inducing textile dermatitis, concomitant testing with allergens from the textile dyes and resin groups is recommended when investigating patients with textile dermatitis."
1234342,Amin and  Ragab 2004,Spectrophotometric determination of certain cephalosporins in pure form and in pharmaceutical formulations,"A simple and reproducible spectrophotometeric method for the assay of cefotaxime sodium, cefuroxime sodium, and ceftriaxone disodium with metol-chromium(VI) reagent has been developed. The procedure is based on direct oxidation of metol by potassium dichromate in presence of drug in acidic medium and subsequent formation of ternary complex. Beer's law is obeyed in the range 0.2-28 microg ml(-1) at lambdamax 520 nm. For more accurate analysis, Ringbom optimum concentration range is found to be 0.8-26.5 microg ml(-1). The molar absorptivity and Sandell sensitivity were calculated. Six replicate analysis of solutions containing seven different concentrations of the examined drugs were carried out and gave a mean correlation coefficient &lt; or =0.9996; the factors of the regression line equation for the three cephalosporins were calculated. The proposed method was applied to the determination of the examined drugs in pharmaceutical formulations and the results demonstrated that the method is equally accurate, precise, and reproducible as the official methods.","Spectrophotometric determination of certain cephalosporins in pure form and in pharmaceutical formulations Abs: A simple and reproducible spectrophotometeric method for the assay of cefotaxime sodium, cefuroxime sodium, and ceftriaxone disodium with metol-chromium(VI) reagent has been developed. The procedure is based on direct oxidation of metol by potassium dichromate in presence of drug in acidic medium and subsequent formation of ternary complex. Beer's law is obeyed in the range 0.2-28 microg ml(-1) at lambdamax 520 nm. For more accurate analysis, Ringbom optimum concentration range is found to be 0.8-26.5 microg ml(-1). The molar absorptivity and Sandell sensitivity were calculated. Six replicate analysis of solutions containing seven different concentrations of the examined drugs were carried out and gave a mean correlation coefficient &lt; or =0.9996; the factors of the regression line equation for the three cephalosporins were calculated. The proposed method was applied to the determination of the examined drugs in pharmaceutical formulations and the results demonstrated that the method is equally accurate, precise, and reproducible as the official methods."
1234341,Do Hong et al. 2004,Tropical ecotoxicity testing with Ceriodaphnia cornuta,"The Sai Gon-Dong Nai river system in southern Vietnam is of great social and economic importance yet receives a large amount of industrial, domestic, and agricultural discharges. Toxicity assessment has started to become an issue in Vietnam, and it is important to employ a test system that is appropriate for typical Vietnamese conditions with a species that is representative of the invertebrates living in its aquatic ecosystems. The aim of this study was to develop and to validate an ecotoxicity test with an autochthonous organism. The microcrustacean Ceriodaphnia cornuta (Cladocera) was isolated from the Sai Gon River. A protocol was developed for the culturing of the organisms, and satisfactory results were obtained for long-term reproduction of C. cornuta. Quality control criteria were established. The toxicity of two relevant pesticides (diazinon and methyl parathion) and two metals (chromium and mercury) to C. cornuta was evaluated and compared to the standard organisms for ecotoxicological testing: Daphnia magna and Vibrio fischeri. Nonlinear regression models were applied to estimate such parameters as EC(50). The results of acute toxicity tests showed that C. cornuta was less tolerant than D. magna and V. fischeri to salinity and that C. cornuta was more sensitive than D. magna and V. fischeri to potassium dichromate, diazinon, methyl parathion, and mercury.","Tropical ecotoxicity testing with Ceriodaphnia cornuta Abs: The Sai Gon-Dong Nai river system in southern Vietnam is of great social and economic importance yet receives a large amount of industrial, domestic, and agricultural discharges. Toxicity assessment has started to become an issue in Vietnam, and it is important to employ a test system that is appropriate for typical Vietnamese conditions with a species that is representative of the invertebrates living in its aquatic ecosystems. The aim of this study was to develop and to validate an ecotoxicity test with an autochthonous organism. The microcrustacean Ceriodaphnia cornuta (Cladocera) was isolated from the Sai Gon River. A protocol was developed for the culturing of the organisms, and satisfactory results were obtained for long-term reproduction of C. cornuta. Quality control criteria were established. The toxicity of two relevant pesticides (diazinon and methyl parathion) and two metals (chromium and mercury) to C. cornuta was evaluated and compared to the standard organisms for ecotoxicological testing: Daphnia magna and Vibrio fischeri. Nonlinear regression models were applied to estimate such parameters as EC(50). The results of acute toxicity tests showed that C. cornuta was less tolerant than D. magna and V. fischeri to salinity and that C. cornuta was more sensitive than D. magna and V. fischeri to potassium dichromate, diazinon, methyl parathion, and mercury."
1234340,Chun et al. 2004,Evaluation of current techniques for isolation of chars as natural adsorbents,"Chars in soils or sediments may potentially influence the soil/sediment sorption behavior. Current techniques for the isolation of black carbon including chars rely often on acid demineralization, base extraction, and chemical oxidation to remove salts and minerals, humic acid, and refractory kerogen, respectively. Little is known about the potential effects of these chemical processes on the char surface and adsorptive properties. This study examined the effects of acid demineralization, base extraction, and acidic Cr2O7 2- oxidation on the surface areas, surface acidity, and benzene adsorption characteristics of laboratory-produced pinewood and wheat-residue chars, pure or mixed with soils, and a commercial activated carbon. Demineralization resulted in a small reduction in the char surface area, whereas base extraction showed no obvious effect. Neither demineralization nor base extraction caused an appreciable variation in benzene adsorption and presumably the char surface properties. By contrast, the Cr2O7 2- oxidation caused a &gt;31% reduction in char surface area. The Boehm titration, supplemented by FTIR spectra, indicated that the surface acidity of oxidized chars increased by a factor between 2.3 and 12 compared to non-oxidized chars. Benzene adsorption with the oxidized chars was lower than that with the non-oxidized chars by a factor of &gt;8.9; both the decrease in char surface area and the increase in char surface acidity contributed to the reduction in char adsorptive power. Although the Cr2O7 2-oxidation effectively removes resistant kerogen, it is not well suited for the isolation of chars as contaminant adsorbents because of its destructive nature. Alternative nondestructive techniques that preserve the char surface properties and effectively remove kerogen must be sought.","Evaluation of current techniques for isolation of chars as natural adsorbents Abs: Chars in soils or sediments may potentially influence the soil/sediment sorption behavior. Current techniques for the isolation of black carbon including chars rely often on acid demineralization, base extraction, and chemical oxidation to remove salts and minerals, humic acid, and refractory kerogen, respectively. Little is known about the potential effects of these chemical processes on the char surface and adsorptive properties. This study examined the effects of acid demineralization, base extraction, and acidic Cr2O7 2- oxidation on the surface areas, surface acidity, and benzene adsorption characteristics of laboratory-produced pinewood and wheat-residue chars, pure or mixed with soils, and a commercial activated carbon. Demineralization resulted in a small reduction in the char surface area, whereas base extraction showed no obvious effect. Neither demineralization nor base extraction caused an appreciable variation in benzene adsorption and presumably the char surface properties. By contrast, the Cr2O7 2- oxidation caused a &gt;31% reduction in char surface area. The Boehm titration, supplemented by FTIR spectra, indicated that the surface acidity of oxidized chars increased by a factor between 2.3 and 12 compared to non-oxidized chars. Benzene adsorption with the oxidized chars was lower than that with the non-oxidized chars by a factor of &gt;8.9; both the decrease in char surface area and the increase in char surface acidity contributed to the reduction in char adsorptive power. Although the Cr2O7 2-oxidation effectively removes resistant kerogen, it is not well suited for the isolation of chars as contaminant adsorbents because of its destructive nature. Alternative nondestructive techniques that preserve the char surface properties and effectively remove kerogen must be sought."
1234339,Yariktas et al. 2004,Allergic contact dermatitis prevalence in patients with eczematous external otitis,"Eczematous external otitis, because of its basic allergic nature, tends to be chronic or recurrent. The purpose of our study was to investigate the association between allergic contact dermatitis and chronic eczematous external otitis. Sixty-six patients with eczematous external otitis and 48 healthy volunteers were included in this study. All the patients were tested with an epicutaneous patch test. In the study group, the average recurrent attack rate was 6.1+/-1.5 (between 4-9 times during the last year) in the patch test positive eczematous external otitis patients, and 4.9+/-1.3 (between 4-8 times during the last year) in the patch test negative patients (p = 0.002). The epicutaneous patch test was positive in 19 (28.8%) out of 66 cases with chronic eczematous external otitis, and in 3 (6.3%) out of 48 cases in the control group. The difference between the two groups was statistically significant (p = 0.003). The most common reactions were due to neomycin sulfate and potassium dichromate in this study. These results suggest that, in some cases eczematous external otitis may be considered as a form of delayed type hypersensitivity to allergen stimuli. Patients suffering from eczematous external otitis symptoms should be investigated for allergens.","Allergic contact dermatitis prevalence in patients with eczematous external otitis Abs: Eczematous external otitis, because of its basic allergic nature, tends to be chronic or recurrent. The purpose of our study was to investigate the association between allergic contact dermatitis and chronic eczematous external otitis. Sixty-six patients with eczematous external otitis and 48 healthy volunteers were included in this study. All the patients were tested with an epicutaneous patch test. In the study group, the average recurrent attack rate was 6.1+/-1.5 (between 4-9 times during the last year) in the patch test positive eczematous external otitis patients, and 4.9+/-1.3 (between 4-8 times during the last year) in the patch test negative patients (p = 0.002). The epicutaneous patch test was positive in 19 (28.8%) out of 66 cases with chronic eczematous external otitis, and in 3 (6.3%) out of 48 cases in the control group. The difference between the two groups was statistically significant (p = 0.003). The most common reactions were due to neomycin sulfate and potassium dichromate in this study. These results suggest that, in some cases eczematous external otitis may be considered as a form of delayed type hypersensitivity to allergen stimuli. Patients suffering from eczematous external otitis symptoms should be investigated for allergens."
1234334,Marinovi?-Kulisi? et al. 2004,"Retrospective survey of patch testing at department of dermatology and venerology, zagreb university hospital center in zagreb, croatia","Epicutaneous (patch) test is a standard test to confirm contact allergy. During a six-year period (1998-2003), contact allergic dermatitis was diagnosed in 4132 (65%) of 6341 patients using standard patch test with a Croatian series of allergens according to the International Contact Dermatitis Research Group (ICDRG). The most common clinical diagnoses related to contact allergy (male; female) were contact allergic dermatitis (65.4%; 72.2%); atopic dermatitis (15.9%; 11.7%); contact irritant dermatitis (7.0%; 6.6%) and nummular eczematoid dermatitis (4.2%; 2.4%). According to occupation, positive patch test reaction was most commonly observed in workers, whereas 65% of patients showed positive reactions to one or more substances. There was an increased frequency of positive patch test reactions to potassium dichromate, nickel sulfate, thimerosal and neomycine sulfate, along with a significant decrease in the frequency of positive patch test reactions to cobalt chloride, carba mix, wood tars, detergents, parabens mixture, urushiol and rubber mixture. We strongly recommend keeping up-to-date with the epidemiology of contact allergy in Croatia.","Retrospective survey of patch testing at department of dermatology and venerology, zagreb university hospital center in zagreb, croatia Abs: Epicutaneous (patch) test is a standard test to confirm contact allergy. During a six-year period (1998-2003), contact allergic dermatitis was diagnosed in 4132 (65%) of 6341 patients using standard patch test with a Croatian series of allergens according to the International Contact Dermatitis Research Group (ICDRG). The most common clinical diagnoses related to contact allergy (male; female) were contact allergic dermatitis (65.4%; 72.2%); atopic dermatitis (15.9%; 11.7%); contact irritant dermatitis (7.0%; 6.6%) and nummular eczematoid dermatitis (4.2%; 2.4%). According to occupation, positive patch test reaction was most commonly observed in workers, whereas 65% of patients showed positive reactions to one or more substances. There was an increased frequency of positive patch test reactions to potassium dichromate, nickel sulfate, thimerosal and neomycine sulfate, along with a significant decrease in the frequency of positive patch test reactions to cobalt chloride, carba mix, wood tars, detergents, parabens mixture, urushiol and rubber mixture. We strongly recommend keeping up-to-date with the epidemiology of contact allergy in Croatia."
1234333,Alam et al. 2005,Effect of Rheum emodi (Revand Hindi) on renal functions in rats,"The renal effects of water-soluble (W-S) and water-insoluble (W-INS) portions of the alcoholic extract of Revand Hindi (Rheum emodi) were investigated on cadmium chloride, mercuric chloride, potassium dichromate and gentamicin-induced nephrotoxicity in rats and normal rats by monitoring the levels of urea nitrogen and creatinine in serum. The present investigations provide evidences that W-S fraction has nephroprotective effect on all the proximal tubule segments (S1, S2 and S3) possibly through antioxidant action of the tannins present in the fraction. W-INS also improved the renal function by protecting S2 segment of proximal tubule nephrotoxicity induced by metals viz cadmium chloride and mercuric chloride in rat models, however, this fraction has been found to enhance gentamicin nephrotoxicity.","Effect of Rheum emodi (Revand Hindi) on renal functions in rats Abs: The renal effects of water-soluble (W-S) and water-insoluble (W-INS) portions of the alcoholic extract of Revand Hindi (Rheum emodi) were investigated on cadmium chloride, mercuric chloride, potassium dichromate and gentamicin-induced nephrotoxicity in rats and normal rats by monitoring the levels of urea nitrogen and creatinine in serum. The present investigations provide evidences that W-S fraction has nephroprotective effect on all the proximal tubule segments (S1, S2 and S3) possibly through antioxidant action of the tannins present in the fraction. W-INS also improved the renal function by protecting S2 segment of proximal tubule nephrotoxicity induced by metals viz cadmium chloride and mercuric chloride in rat models, however, this fraction has been found to enhance gentamicin nephrotoxicity."
1234332,Sinha et al. 2005,Chromium induced lipid peroxidation in the plants of Pistia stratiotes L.: role of antioxidants and antioxidant enzymes,"In the plant, Pistia stratiotes L., the effect of different concentrations of chromium (0, 10, 40, 80 and 160 microM) applied for 48, 96 and 144 h was assessed by measuring changes in the chlorophyll, protein, malondialdehyde (MDA), cysteine, non-protein thiol, ascorbic acid contents and superoxide dismutase (SOD), ascorbate peroxidase (APX) and guiacol peroxidase (GPX) activity of the plants. Both in roots and leaves, an increase in MDA content was observed with increase in metal concentration and exposure periods. In roots, the activity of antioxidant enzymes viz. SOD and APX increased at all the concentrations of Cr at 144 h than their controls. The GPX activity of the treated roots increased with increase in Cr concentration at 48 and 96 h of exposures, however, at 144 h its activity was found declined beyond 10 microM Cr. The level of antioxidants in the roots of the treated plant viz. cysteine and ascorbic acid was also found increased at all the concentrations of Cr at 144 h than their respective controls, however, an increase in the non-protein thiol content was recorded up to 40 microM Cr followed by decrease. The chlorophyll content decreased with increase in Cr concentrations and exposure periods. However, the protein content of both roots and leaves were found decreased with increase in Cr concentrations at all the exposure periods except an increase was recorded at 10 microM Cr at 48 h. In Cr treated plants, the no observed effect concentration (NOEC) and lowest observed effect concentration (LOEC) for leaves chlorophyll and protein contents were 40 and 80 microM Cr, respectively after 48 h exposure while NOEC and LOEC for root protein content were 10 and 40 microM, respectively after 48 h. The analysis of correlation coefficient data revealed that the metal accumulation in the roots of the plant was found positively correlated with antioxidant parameters except SOD after 48 h of exposure, however, negatively correlated with most of all the parameters studied at 144 h in both part of the plant. It may be suggested from the present study that toxic concentrations of Cr cause oxidative damage as evidenced by increased lipid peroxidation and decreased chlorophyll and protein contents. However, the higher levels of enzymatic and non-enzymatic antioxidants suggest the reason for tolerating higher levels of metals.","Chromium induced lipid peroxidation in the plants of Pistia stratiotes L.: role of antioxidants and antioxidant enzymes Abs: In the plant, Pistia stratiotes L., the effect of different concentrations of chromium (0, 10, 40, 80 and 160 microM) applied for 48, 96 and 144 h was assessed by measuring changes in the chlorophyll, protein, malondialdehyde (MDA), cysteine, non-protein thiol, ascorbic acid contents and superoxide dismutase (SOD), ascorbate peroxidase (APX) and guiacol peroxidase (GPX) activity of the plants. Both in roots and leaves, an increase in MDA content was observed with increase in metal concentration and exposure periods. In roots, the activity of antioxidant enzymes viz. SOD and APX increased at all the concentrations of Cr at 144 h than their controls. The GPX activity of the treated roots increased with increase in Cr concentration at 48 and 96 h of exposures, however, at 144 h its activity was found declined beyond 10 microM Cr. The level of antioxidants in the roots of the treated plant viz. cysteine and ascorbic acid was also found increased at all the concentrations of Cr at 144 h than their respective controls, however, an increase in the non-protein thiol content was recorded up to 40 microM Cr followed by decrease. The chlorophyll content decreased with increase in Cr concentrations and exposure periods. However, the protein content of both roots and leaves were found decreased with increase in Cr concentrations at all the exposure periods except an increase was recorded at 10 microM Cr at 48 h. In Cr treated plants, the no observed effect concentration (NOEC) and lowest observed effect concentration (LOEC) for leaves chlorophyll and protein contents were 40 and 80 microM Cr, respectively after 48 h exposure while NOEC and LOEC for root protein content were 10 and 40 microM, respectively after 48 h. The analysis of correlation coefficient data revealed that the metal accumulation in the roots of the plant was found positively correlated with antioxidant parameters except SOD after 48 h of exposure, however, negatively correlated with most of all the parameters studied at 144 h in both part of the plant. It may be suggested from the present study that toxic concentrations of Cr cause oxidative damage as evidenced by increased lipid peroxidation and decreased chlorophyll and protein contents. However, the higher levels of enzymatic and non-enzymatic antioxidants suggest the reason for tolerating higher levels of metals."
1234331,Shrivastava et al. 2005,Effects of chromium on the resident gut bacteria of rat,"The major nonoccupational source of chromium (Cr) for humans is through ingestion with food and water, but its effect on the gut microflora has not been studied. The present study was, therefore, undertaken to investigate the effects of chronic ingestion of potassium dichromate (chromium VI) on the resident gut bacteria of male Wistar rats. A group of rats was kept on drinking water containing 10 ppm chromium VI (Cr [VI]) (called Cr-stressed animals) and the other group was given plain water. After 10 weeks, Lactobacillus, Pseudomonas sp., and Escherichia coli were isolated from the cecum of the rats and various studies were performed. The most significant findings of the present study were the stimulation of growth of facultative gut bacteria from the Cr-stressed rats and the significant increase of growth even in the presence of lower concentrations of Cr. Furthermore, the capacity to reduce Cr (VI) was significantly decreased along with the increased tolerance of the bacteria to Cr (higher minimum inhibitory concentration [MIC] values), which was associated with the development of antibiotic resistance. The effects were most marked with the Pseudomonas sp. and least with the E. coli. The antibiotic resistance developed with the Lactobacillus may be a blessing in disguise, because the bacteria may continue to provide benefits even in patients given antibiotic therapy. The gut bacteria thus provide the first line of defense to the body by converting toxic Cr (VI) to a less toxic Cr (III) and may act as a prebiotic.","Effects of chromium on the resident gut bacteria of rat Abs: The major nonoccupational source of chromium (Cr) for humans is through ingestion with food and water, but its effect on the gut microflora has not been studied. The present study was, therefore, undertaken to investigate the effects of chronic ingestion of potassium dichromate (chromium VI) on the resident gut bacteria of male Wistar rats. A group of rats was kept on drinking water containing 10 ppm chromium VI (Cr [VI]) (called Cr-stressed animals) and the other group was given plain water. After 10 weeks, Lactobacillus, Pseudomonas sp., and Escherichia coli were isolated from the cecum of the rats and various studies were performed. The most significant findings of the present study were the stimulation of growth of facultative gut bacteria from the Cr-stressed rats and the significant increase of growth even in the presence of lower concentrations of Cr. Furthermore, the capacity to reduce Cr (VI) was significantly decreased along with the increased tolerance of the bacteria to Cr (higher minimum inhibitory concentration [MIC] values), which was associated with the development of antibiotic resistance. The effects were most marked with the Pseudomonas sp. and least with the E. coli. The antibiotic resistance developed with the Lactobacillus may be a blessing in disguise, because the bacteria may continue to provide benefits even in patients given antibiotic therapy. The gut bacteria thus provide the first line of defense to the body by converting toxic Cr (VI) to a less toxic Cr (III) and may act as a prebiotic."
1234329,Seidenari et al. 2005,Contact sensitization in 1094 children undergoing patch testing over a 7-year period,"Contact sensitization in children is frequent. However, because exposure to sensitizing agents varies rapidly, it is of utmost importance to perform a periodic evaluation of patch test results. Our purpose was to compare our data on contact sensitization in children during the past 7 years to our previous 1988-1994 findings, in order to identify emerging allergens and update our pediatric series. From 1995 to 2001, 1094 consecutive children were examined. Of these, 997 patients were patch tested with our pediatric series, which includes 30 allergens, whereas 97 underwent patch testing with 46 allergens. A total of 570 children proved allergic (52.1%). The highest sensitization rate was observed in children under 3 years of age. No differences between atopic dermatitis patients and nonatopic ones were observed in the sensitization rate. Neomycin, nickel, wool alcohols, thimerosal, and ammoniated mercury gave most of the positive responses. With respect to 1988-1995 data, allergy to substances such as neomycin, nickel, wool alcohols, thimerosal, ammoniated mercury, propolis, potassium dichromate, and thiuram mix proved more frequent. In conclusion, as sensitization rates to different allergens show great variations over time, periodic evaluations of patch test results in children is necessary in order to update the test trays.","Contact sensitization in 1094 children undergoing patch testing over a 7-year period Abs: Contact sensitization in children is frequent. However, because exposure to sensitizing agents varies rapidly, it is of utmost importance to perform a periodic evaluation of patch test results. Our purpose was to compare our data on contact sensitization in children during the past 7 years to our previous 1988-1994 findings, in order to identify emerging allergens and update our pediatric series. From 1995 to 2001, 1094 consecutive children were examined. Of these, 997 patients were patch tested with our pediatric series, which includes 30 allergens, whereas 97 underwent patch testing with 46 allergens. A total of 570 children proved allergic (52.1%). The highest sensitization rate was observed in children under 3 years of age. No differences between atopic dermatitis patients and nonatopic ones were observed in the sensitization rate. Neomycin, nickel, wool alcohols, thimerosal, and ammoniated mercury gave most of the positive responses. With respect to 1988-1995 data, allergy to substances such as neomycin, nickel, wool alcohols, thimerosal, ammoniated mercury, propolis, potassium dichromate, and thiuram mix proved more frequent. In conclusion, as sensitization rates to different allergens show great variations over time, periodic evaluations of patch test results in children is necessary in order to update the test trays."
1234328,Hegewald et al. 2005,"A multifactorial analysis of concurrent patch-test reactions to nickel, cobalt, and chromate","<strong>BACKGROUND: </strong>Previous research indicates that positive patch tests to nickel (II) sulphate, cobalt (II) chloride and potassium dichromate commonly occur together.<br /><br /><strong>METHODS: </strong>To further examine the relationship between nickel, cobalt, chromate, and the factors that may potentially be related to concurrent sensitizations to two or all three metal allergens, data from the Information Network of Dermatology Departments have been investigated.<br /><br /><strong>RESULTS: </strong>Women had a higher conditional odds of concurrent nickel-cobalt (OR = 6.80; 95% CI: 5.65-8.19) and nickel-chromate (OR = 2.13; 95% CI: 1.67-2.72) reactions than men. Construction workers had a significantly higher odds of cobalt-chromate reactions (OR = 13.89; 95% CI: 10.36-18.64), while the odds of isolated cobalt allergy was only 0.92 (95% CI: 0.48-1.74). Patients with underlying atopic eczema/dermatitis syndrome had a 40-90% higher chance of any positive outcome, which involved chromate. Polysensitization, defined as the number of positive reactions to standard series substances other than nickel, cobalt, and chromate, was also significantly associated with the concurrent reactions; moreover, steady and significant effect gradients were noted.<br /><br /><strong>CONCLUSIONS: </strong>This research confirms the occupational nature of cobalt-chromate concurrent reactions, in particular, in construction workers. Polysensitization, which is considered to represent susceptibility to delayed-hypersensitivity in general, is also associated with the concurrent reactions to the metals. Hence, not only coupled exposure, but also individual susceptibility may be responsible for concurrent reactions to metals in man.","A multifactorial analysis of concurrent patch-test reactions to nickel, cobalt, and chromate Abs: <strong>BACKGROUND: </strong>Previous research indicates that positive patch tests to nickel (II) sulphate, cobalt (II) chloride and potassium dichromate commonly occur together.<br /><br /><strong>METHODS: </strong>To further examine the relationship between nickel, cobalt, chromate, and the factors that may potentially be related to concurrent sensitizations to two or all three metal allergens, data from the Information Network of Dermatology Departments have been investigated.<br /><br /><strong>RESULTS: </strong>Women had a higher conditional odds of concurrent nickel-cobalt (OR = 6.80; 95% CI: 5.65-8.19) and nickel-chromate (OR = 2.13; 95% CI: 1.67-2.72) reactions than men. Construction workers had a significantly higher odds of cobalt-chromate reactions (OR = 13.89; 95% CI: 10.36-18.64), while the odds of isolated cobalt allergy was only 0.92 (95% CI: 0.48-1.74). Patients with underlying atopic eczema/dermatitis syndrome had a 40-90% higher chance of any positive outcome, which involved chromate. Polysensitization, defined as the number of positive reactions to standard series substances other than nickel, cobalt, and chromate, was also significantly associated with the concurrent reactions; moreover, steady and significant effect gradients were noted.<br /><br /><strong>CONCLUSIONS: </strong>This research confirms the occupational nature of cobalt-chromate concurrent reactions, in particular, in construction workers. Polysensitization, which is considered to represent susceptibility to delayed-hypersensitivity in general, is also associated with the concurrent reactions to the metals. Hence, not only coupled exposure, but also individual susceptibility may be responsible for concurrent reactions to metals in man."
1234327,Jappe et al. 2005,Rosacea and contact allergy to cosmetics and topical medicaments--retrospective analysis of multicentre surveillance data 1995-2002,"The role of contact allergy in rosacea has rarely been investigated. In this retrospective study, 361 out of 76,697 patients tested and documented by the Information Network of Departments of Dermatology between 1995 and 2002 had rosacea. Patch tests included standard series and constituents of cosmetics and topical medicaments. 118/361 had additionally been patch tested with their own cosmetics/medicaments. Positive reactions occurred to nickel (II) sulfate in 9.3%, fragrance mix in 8.8%, thimerosal in 6.9%, Myroxylon pereirae resin in 5.9%, potassium dichromate in 4.6% and propolis in 2.8%. Whereas rosacea patients had a significantly higher risk of contact allergy to propolis compared to the remaining patients, in an age- and sex-adjusted analysis, contact allergy to nickel was significantly less frequent in this group. For Lyral, the risk was elevated, albeit not significantly. Only 2/329 patients were positive to neomycin sulfate and 1/100 to gentamicin sulfate, among the panel of (topical) antibiotics tested. Among 118 patients tested with their own products, 3 were tested to metronidazole, 1 reacting positively. Irritant or doubtful patch test reactions were provoked by various substances (vehicles, oxidants and preservatives of various creams), which might also be clinically important, considering the heightened sensitivity of rosaceous skin.","Rosacea and contact allergy to cosmetics and topical medicaments--retrospective analysis of multicentre surveillance data 1995-2002 Abs: The role of contact allergy in rosacea has rarely been investigated. In this retrospective study, 361 out of 76,697 patients tested and documented by the Information Network of Departments of Dermatology between 1995 and 2002 had rosacea. Patch tests included standard series and constituents of cosmetics and topical medicaments. 118/361 had additionally been patch tested with their own cosmetics/medicaments. Positive reactions occurred to nickel (II) sulfate in 9.3%, fragrance mix in 8.8%, thimerosal in 6.9%, Myroxylon pereirae resin in 5.9%, potassium dichromate in 4.6% and propolis in 2.8%. Whereas rosacea patients had a significantly higher risk of contact allergy to propolis compared to the remaining patients, in an age- and sex-adjusted analysis, contact allergy to nickel was significantly less frequent in this group. For Lyral, the risk was elevated, albeit not significantly. Only 2/329 patients were positive to neomycin sulfate and 1/100 to gentamicin sulfate, among the panel of (topical) antibiotics tested. Among 118 patients tested with their own products, 3 were tested to metronidazole, 1 reacting positively. Irritant or doubtful patch test reactions were provoked by various substances (vehicles, oxidants and preservatives of various creams), which might also be clinically important, considering the heightened sensitivity of rosaceous skin."
1234326,Frass et al. 2005,Influence of potassium dichromate on tracheal secretions in critically ill patients,"<strong>BACKGROUND: </strong>Stringy, tenacious tracheal secretions may prevent extubation in patients weaned from the respirator. This prospective, randomized, double-blind, placebo-controlled study with parallel assignment was performed to assess the influence of sublingually administered potassium dichromate C30 on the amount of tenacious, stringy tracheal secretions in critically ill patients with a history of tobacco use and COPD.<br /><br /><strong>METHODS: </strong>In this study, 50 patients breathing spontaneously with continuous positive airway pressure were receiving either potassium dichromate C30 globules (group 1) [Deutsche Homoopathie-Union, Pharmaceutical Company; Karlsruhe, Germany] or placebo (group 2). Five globules were administered twice daily at intervals of 12 h. The amount of tracheal secretions on day 2 after the start of the study as well as the time for successful extubation and length of stay in the ICU were recorded.<br /><br /><strong>RESULTS: </strong>The amount of tracheal secretions was reduced significantly in group 1 (p &lt; 0.0001). Extubation could be performed significantly earlier in group 1 (p &lt; 0.0001). Similarly, length of stay was significantly shorter in group 1 (4.20 +/- 1.61 days vs 7.68 +/- 3.60 days, p &lt; 0.0001 [mean +/- SD]).<br /><br /><strong>CONCLUSION: </strong>These data suggest that potentized (diluted and vigorously shaken) potassium dichromate may help to decrease the amount of stringy tracheal secretions in COPD patients.","Influence of potassium dichromate on tracheal secretions in critically ill patients Abs: <strong>BACKGROUND: </strong>Stringy, tenacious tracheal secretions may prevent extubation in patients weaned from the respirator. This prospective, randomized, double-blind, placebo-controlled study with parallel assignment was performed to assess the influence of sublingually administered potassium dichromate C30 on the amount of tenacious, stringy tracheal secretions in critically ill patients with a history of tobacco use and COPD.<br /><br /><strong>METHODS: </strong>In this study, 50 patients breathing spontaneously with continuous positive airway pressure were receiving either potassium dichromate C30 globules (group 1) [Deutsche Homoopathie-Union, Pharmaceutical Company; Karlsruhe, Germany] or placebo (group 2). Five globules were administered twice daily at intervals of 12 h. The amount of tracheal secretions on day 2 after the start of the study as well as the time for successful extubation and length of stay in the ICU were recorded.<br /><br /><strong>RESULTS: </strong>The amount of tracheal secretions was reduced significantly in group 1 (p &lt; 0.0001). Extubation could be performed significantly earlier in group 1 (p &lt; 0.0001). Similarly, length of stay was significantly shorter in group 1 (4.20 +/- 1.61 days vs 7.68 +/- 3.60 days, p &lt; 0.0001 [mean +/- SD]).<br /><br /><strong>CONCLUSION: </strong>These data suggest that potentized (diluted and vigorously shaken) potassium dichromate may help to decrease the amount of stringy tracheal secretions in COPD patients."
1234323,Pedraza-Chaverrí et al. 2005,Time course study of oxidative and nitrosative stress and antioxidant enzymes in K2Cr2O7-induced nephrotoxicity,"<strong>BACKGROUND: </strong>Potassium dichromate (K2Cr2O7)-induced nephrotoxicity is associated with oxidative and nitrosative stress. In this study we investigated the relation between the time course of the oxidative and nitrosative stress with kidney damage and alterations in the following antioxidant enzymes: Cu, Zn superoxide dismutase (Cu, Zn-SOD), Mn-SOD, glutathione peroxidase (GPx), glutathione reductase (GR), and catalase (CAT).<br /><br /><strong>METHODS: </strong>Nephrotoxicity was induced in rats by a single injection of K2Cr2O7. Groups of animals were sacrificed on days 1,2,3,4,6,8,10, and 12. Nephrotoxicity was evaluated by histological studies and by measuring creatinine clearance, serum creatinine, blood urea nitrogen (BUN), and urinary excretion of N-acetyl-beta-D-glucosaminidase (NAG) and total protein. Oxidative and nitrosative stress were measured by immunohistochemical localization of protein carbonyls and 3-nitrotyrosine, respectively. Cu, Zn-SOD, Mn-SOD, and CAT were studied by immunohistochemical localization. The activity of total SOD, CAT, GPx, and GR was also measured as well as serum and kidney content of chromium and urinary excretion of NO2 -/NO3-. Data were compared by two-way analysis of variance followed by a post hoc test.<br /><br /><strong>RESULTS: </strong>Serum and kidney chromium content increased reaching the highest value on day 1. Nephrotoxicity was made evident by the decrease in creatinine clearance (days 1-4) and by the increase in serum creatinine (days 1-4), BUN (days 1-6), urinary excretion of NAG (days 1-4), and total protein (day 1-6) and by the structural damage to the proximal tubules (days 1-6). Oxidative and nitrosative stress were clearly evident on days 1-8. Urinary excretion of NO2-/NO3- decreased on days 2-6. Mn-SOD and Cu, Zn-SOD, estimated by immunohistochemistry, and total SOD activity remained unchanged. Activity of GPx decreased on days 3-12 and those of GR and CAT on days 2-10. Similar findings were observed by immunohistochemistry of CAT.<br /><br /><strong>CONCLUSION: </strong>These data show the association between oxidative and nitrosative stress with functional and structural renal damage induced by K2Cr2O7. Renal antioxidant enzymes were regulated differentially and were not closely associated with oxidative or nitrosative stress or with kidney damage. In addition, the decrease in the urinary excretion of NO2-/NO3- was associated with the renal nitrosative stress suggesting that nitric oxide was derived to the formation of reactive nitrogen species involved in protein nitration.","Time course study of oxidative and nitrosative stress and antioxidant enzymes in K2Cr2O7-induced nephrotoxicity Abs: <strong>BACKGROUND: </strong>Potassium dichromate (K2Cr2O7)-induced nephrotoxicity is associated with oxidative and nitrosative stress. In this study we investigated the relation between the time course of the oxidative and nitrosative stress with kidney damage and alterations in the following antioxidant enzymes: Cu, Zn superoxide dismutase (Cu, Zn-SOD), Mn-SOD, glutathione peroxidase (GPx), glutathione reductase (GR), and catalase (CAT).<br /><br /><strong>METHODS: </strong>Nephrotoxicity was induced in rats by a single injection of K2Cr2O7. Groups of animals were sacrificed on days 1,2,3,4,6,8,10, and 12. Nephrotoxicity was evaluated by histological studies and by measuring creatinine clearance, serum creatinine, blood urea nitrogen (BUN), and urinary excretion of N-acetyl-beta-D-glucosaminidase (NAG) and total protein. Oxidative and nitrosative stress were measured by immunohistochemical localization of protein carbonyls and 3-nitrotyrosine, respectively. Cu, Zn-SOD, Mn-SOD, and CAT were studied by immunohistochemical localization. The activity of total SOD, CAT, GPx, and GR was also measured as well as serum and kidney content of chromium and urinary excretion of NO2 -/NO3-. Data were compared by two-way analysis of variance followed by a post hoc test.<br /><br /><strong>RESULTS: </strong>Serum and kidney chromium content increased reaching the highest value on day 1. Nephrotoxicity was made evident by the decrease in creatinine clearance (days 1-4) and by the increase in serum creatinine (days 1-4), BUN (days 1-6), urinary excretion of NAG (days 1-4), and total protein (day 1-6) and by the structural damage to the proximal tubules (days 1-6). Oxidative and nitrosative stress were clearly evident on days 1-8. Urinary excretion of NO2-/NO3- decreased on days 2-6. Mn-SOD and Cu, Zn-SOD, estimated by immunohistochemistry, and total SOD activity remained unchanged. Activity of GPx decreased on days 3-12 and those of GR and CAT on days 2-10. Similar findings were observed by immunohistochemistry of CAT.<br /><br /><strong>CONCLUSION: </strong>These data show the association between oxidative and nitrosative stress with functional and structural renal damage induced by K2Cr2O7. Renal antioxidant enzymes were regulated differentially and were not closely associated with oxidative or nitrosative stress or with kidney damage. In addition, the decrease in the urinary excretion of NO2-/NO3- was associated with the renal nitrosative stress suggesting that nitric oxide was derived to the formation of reactive nitrogen species involved in protein nitration."
1234321,Trattner and  David 2005,Tefillin dermatitis,"Tefillin (phylacteries) are a religious article worn by observant Jewish men. Only two cases of allergic contact dermatitis from tefillin have been reported previously. We describe 7 new cases of tefillin contact dermatitis and review the literature on contact allergy caused by religious objects and practices. All our patients had contact allergy to potassium dichromate, which was the only allergen relevant to tefillin .","Tefillin dermatitis Abs: Tefillin (phylacteries) are a religious article worn by observant Jewish men. Only two cases of allergic contact dermatitis from tefillin have been reported previously. We describe 7 new cases of tefillin contact dermatitis and review the literature on contact allergy caused by religious objects and practices. All our patients had contact allergy to potassium dichromate, which was the only allergen relevant to tefillin ."
1234318,Rudolf et al. 2005,Zinc has ambiguous effects on chromium (VI)-induced oxidative stress and apoptosis,"Zinc is an important cellular antioxidant. We investigated its role in chromium-induced oxidative stress and apoptosis in human tumor cell line Hep-2. The measured parameters included intracellular labile zinc content (Zinquin-E fluorescence), cell viability (WST-1 assay), oxidative stress (spectrophotometry), mitochondrial potential (flow cytometry), caspase-3 activity, and PARP cleavage (immunofluorescence). We found that Hep-2 cells contain abundant labile zinc stores that may be depleted by the ionophore TPEN or increased by external zinc supplementation. Chromium (VI)-induced cytotoxicity and apoptosis were enhanced in zinc-depleted cells after 24 h, in particular at chromium (VI) concentrations of 50 and 150 micromol/l. On the other hand, elevated levels of labile zinc were able to protect against apoptosis induced by 10 micromol/l chromium (VI) but at higher chromium (VI) concentrations (50 and 150 micromol/l) acted synergistically, significantly enhancing oxidative stress and the course of apoptosis, possibly through oxidative stress and mitochondrial damage.","Zinc has ambiguous effects on chromium (VI)-induced oxidative stress and apoptosis Abs: Zinc is an important cellular antioxidant. We investigated its role in chromium-induced oxidative stress and apoptosis in human tumor cell line Hep-2. The measured parameters included intracellular labile zinc content (Zinquin-E fluorescence), cell viability (WST-1 assay), oxidative stress (spectrophotometry), mitochondrial potential (flow cytometry), caspase-3 activity, and PARP cleavage (immunofluorescence). We found that Hep-2 cells contain abundant labile zinc stores that may be depleted by the ionophore TPEN or increased by external zinc supplementation. Chromium (VI)-induced cytotoxicity and apoptosis were enhanced in zinc-depleted cells after 24 h, in particular at chromium (VI) concentrations of 50 and 150 micromol/l. On the other hand, elevated levels of labile zinc were able to protect against apoptosis induced by 10 micromol/l chromium (VI) but at higher chromium (VI) concentrations (50 and 150 micromol/l) acted synergistically, significantly enhancing oxidative stress and the course of apoptosis, possibly through oxidative stress and mitochondrial damage."
1234317,Anand 2005,Protective effect of vitamin B6 in chromium-induced oxidative stress in liver,"The aim of this study was to examine the efficacy of vitamin B6 against chromium (Cr)-induced oxidative stress. Adult male albino Wistar rats (100-120 g) were used in this study. Potassium dichromate, a Cr VI compound, was administered at a dose of 127 mg kg(-1) p.o. Vitamin B6 (pyridoxine hydrochloride) was administered at a dose of 100 mg kg(-1) p.o. either alone or 12 h prior to Cr or simultaneously with Cr. Chromium treatment induced oxidative stress in the liver as measured by increased lipid peroxidation (LPO) and decreased vitamin C, vitamin E, glutathione (GSH), glutathione peroxidase (GPX), catalase (CAT), superoxide dismutase (SOD), glutathione S-transferase (GST) and glutathione reductase (GR). Both pre- and simultaneous treatments countered Cr-induced oxidative stress; pre-treatment was more effective than concurrent administration. The results demonstrate the antioxidant potential of vitamin B6.","Protective effect of vitamin B6 in chromium-induced oxidative stress in liver Abs: The aim of this study was to examine the efficacy of vitamin B6 against chromium (Cr)-induced oxidative stress. Adult male albino Wistar rats (100-120 g) were used in this study. Potassium dichromate, a Cr VI compound, was administered at a dose of 127 mg kg(-1) p.o. Vitamin B6 (pyridoxine hydrochloride) was administered at a dose of 100 mg kg(-1) p.o. either alone or 12 h prior to Cr or simultaneously with Cr. Chromium treatment induced oxidative stress in the liver as measured by increased lipid peroxidation (LPO) and decreased vitamin C, vitamin E, glutathione (GSH), glutathione peroxidase (GPX), catalase (CAT), superoxide dismutase (SOD), glutathione S-transferase (GST) and glutathione reductase (GR). Both pre- and simultaneous treatments countered Cr-induced oxidative stress; pre-treatment was more effective than concurrent administration. The results demonstrate the antioxidant potential of vitamin B6."
1234316,Sang and  Li 2005,Chromosomal aberrations induced in mouse bone marrow cells by municipal landfill leachate,"The cytogenetic damage induced by municipal landfill leachate was studied using chromosomal aberration (CA) in mouse bone marrow assay. Results show that leachate samples collected in different seasons decreased the mitotic index (MI), and caused significant increases of CA frequencies in treatment concentration (Chemical oxygen demand (COD) measured by the method of potassium dichromate oxidation, COD(Cr))-dependent manners. Compared with the negative control, reductions of the MI of 54 and 38% were detected for the highest leachate concentration (COD(Cr) 320mg/L) in mouse bone marrow treated with both samples. The frequencies of CA increased significantly with increasing concentrations of sample 1 from COD(Cr) 40 to 320mg/L, and from 80 to 320mg/L after exposure to sample 2. In addition, a seasonal difference of MI and CA frequencies induced by leachate was observed. The results confirm that leachate is a genotoxic agent in mammalian cells, and imply that exposure to leachate in aquatic environment may pose a potential genotoxic risk to mammals and humans. The results suggest that the CA in mouse bone marrow bioassay is efficient in genotoxicity studies of leachate on mammals, and that there appears to be a correlation between the genotoxicity in mammal system and the chemical measurement (COD(Cr)) of leachate. The results also indicate that different discharge guidelines and environmental quality standards should be established for leachates discharged from landfills to aquatic environment in different seasons.","Chromosomal aberrations induced in mouse bone marrow cells by municipal landfill leachate Abs: The cytogenetic damage induced by municipal landfill leachate was studied using chromosomal aberration (CA) in mouse bone marrow assay. Results show that leachate samples collected in different seasons decreased the mitotic index (MI), and caused significant increases of CA frequencies in treatment concentration (Chemical oxygen demand (COD) measured by the method of potassium dichromate oxidation, COD(Cr))-dependent manners. Compared with the negative control, reductions of the MI of 54 and 38% were detected for the highest leachate concentration (COD(Cr) 320mg/L) in mouse bone marrow treated with both samples. The frequencies of CA increased significantly with increasing concentrations of sample 1 from COD(Cr) 40 to 320mg/L, and from 80 to 320mg/L after exposure to sample 2. In addition, a seasonal difference of MI and CA frequencies induced by leachate was observed. The results confirm that leachate is a genotoxic agent in mammalian cells, and imply that exposure to leachate in aquatic environment may pose a potential genotoxic risk to mammals and humans. The results suggest that the CA in mouse bone marrow bioassay is efficient in genotoxicity studies of leachate on mammals, and that there appears to be a correlation between the genotoxicity in mammal system and the chemical measurement (COD(Cr)) of leachate. The results also indicate that different discharge guidelines and environmental quality standards should be established for leachates discharged from landfills to aquatic environment in different seasons."
1234315,Carbert and  Venn 2005,Recently published papers: out with the old and in with the new ... then something new for the old!,"New therapies are challenging older, established practices. One recently published report shows us that we may be able to avoid endotracheal intubation in patients with a reduced level of consciousness. Recombinant activated factor VII is proving to be useful in many coagulation disorders, and intracerebral haemorrhage can be added to this list. Homeopathy, in the form of potassium dichromate, shows promise as a new treatment for excessive tracheal secretions. Rotation protocols for antibiotics have been evaluated with respect to their ability to prevent the development of new resistant micro-organisms in our hospitals and units. Finally, glucocorticoids may be of benefit to septic patients outside the intensive care unit (ICU) and may prevent their deterioration and admission to the ICU.","Recently published papers: out with the old and in with the new ... then something new for the old! Abs: New therapies are challenging older, established practices. One recently published report shows us that we may be able to avoid endotracheal intubation in patients with a reduced level of consciousness. Recombinant activated factor VII is proving to be useful in many coagulation disorders, and intracerebral haemorrhage can be added to this list. Homeopathy, in the form of potassium dichromate, shows promise as a new treatment for excessive tracheal secretions. Rotation protocols for antibiotics have been evaluated with respect to their ability to prevent the development of new resistant micro-organisms in our hospitals and units. Finally, glucocorticoids may be of benefit to septic patients outside the intensive care unit (ICU) and may prevent their deterioration and admission to the ICU."
1234313,Budhwar and  Kumar 2005,Prevention of chromate induced oxidative stress by alpha-lipoic acid,"The parenteral administration of alpha-lipoic acid (LA) protected against chromate induced oxidative stress in mouse liver. A shift in Cr induced pro-oxidant state to antioxidant-state by LA was noteworthy. The degree of protection was significant and similar in different LA administration regimens (prior-, co- and post- parenteral Cr exposure) explored. An improved status of the tissue antioxidants by LA appeared to be the mechanism of mitigation. The results are of chemopreventive value and suggest a possible alternative to ascorbic acid for abrogation of Cr toxicity.","Prevention of chromate induced oxidative stress by alpha-lipoic acid Abs: The parenteral administration of alpha-lipoic acid (LA) protected against chromate induced oxidative stress in mouse liver. A shift in Cr induced pro-oxidant state to antioxidant-state by LA was noteworthy. The degree of protection was significant and similar in different LA administration regimens (prior-, co- and post- parenteral Cr exposure) explored. An improved status of the tissue antioxidants by LA appeared to be the mechanism of mitigation. The results are of chemopreventive value and suggest a possible alternative to ascorbic acid for abrogation of Cr toxicity."
1234310,Toebak et al. 2006,CXCL8 secretion by dendritic cells predicts contact allergens from irritants,"Monocyte-derived dendritic cell functions have been explored for identification of contact allergens in vitro. Current methods, including measurement of changes in cell surface marker expression (e.g. CD83, CD86) do not provide a sensitive method for detecting the sensitising potential of a chemical. In this study, we investigated whether chemokine production by monocyte-derived dendritic cells is increased upon maturation and whether chemokine production can provide methodology for the detection of allergens. Monocyte-derived dendritic cells were exposed to allergens (nickel sulphate, cobalt chloride, palladium chloride, copper sulphate, chrome-(III)-chloride, potassium dichromate, p-phenylenediamine and dinitrochlorobenzene) and irritants (sodium dodecyl sulphate, dimethylsulphoxide, benzalkoniumchloride and propane-1-ol). CD83 and CD86 expression was analysed by flow cytometry and chemokine production (CXCL8, CCL5, CCL17, CCL18, CCL19, CCL20, CCL22) was determined by ELISA. Significant up regulation of CD83 and CD86 expression could only be induced by three out of seven and five out of seven allergens, respectively. In contrast, CXCL8 production was significantly increased after stimulation with all allergens tested, whereas irritant exposure led to decreased CXCL8 production. All other chemokines tested, failed in identifying contact allergens. In conclusion, CXCL8 production, next to CD83 and CD86 up regulation, by monocyte-derived dendritic cells provides a promising in vitro tool for discrimination between allergens and irritants.","CXCL8 secretion by dendritic cells predicts contact allergens from irritants Abs: Monocyte-derived dendritic cell functions have been explored for identification of contact allergens in vitro. Current methods, including measurement of changes in cell surface marker expression (e.g. CD83, CD86) do not provide a sensitive method for detecting the sensitising potential of a chemical. In this study, we investigated whether chemokine production by monocyte-derived dendritic cells is increased upon maturation and whether chemokine production can provide methodology for the detection of allergens. Monocyte-derived dendritic cells were exposed to allergens (nickel sulphate, cobalt chloride, palladium chloride, copper sulphate, chrome-(III)-chloride, potassium dichromate, p-phenylenediamine and dinitrochlorobenzene) and irritants (sodium dodecyl sulphate, dimethylsulphoxide, benzalkoniumchloride and propane-1-ol). CD83 and CD86 expression was analysed by flow cytometry and chemokine production (CXCL8, CCL5, CCL17, CCL18, CCL19, CCL20, CCL22) was determined by ELISA. Significant up regulation of CD83 and CD86 expression could only be induced by three out of seven and five out of seven allergens, respectively. In contrast, CXCL8 production was significantly increased after stimulation with all allergens tested, whereas irritant exposure led to decreased CXCL8 production. All other chemokines tested, failed in identifying contact allergens. In conclusion, CXCL8 production, next to CD83 and CD86 up regulation, by monocyte-derived dendritic cells provides a promising in vitro tool for discrimination between allergens and irritants."
1234308,Wetter et al. 2005,"Patch test results from the Mayo Clinic Contact Dermatitis Group, 1998-2000","<strong>BACKGROUND: </strong>Patch testing is a diagnostic tool for the evaluation of patients with suspected allergic contact dermatitis. A standard series of allergens similar to that used by the North American Contact Dermatitis Group (NACDG) is used at Mayo Clinic.<br /><br /><strong>OBJECTIVE: </strong>Our aim was to report the results of patch testing with a standard series at Mayo Clinic from July 1, 1998, to Dec 31, 2000 and to compare our findings with those of the NACDG during the same period.<br /><br /><strong>METHODS: </strong>The results of patch testing with the standard series at Mayo Clinic were examined. Positive reaction rates were compared between Mayo Clinic and the NACDG.<br /><br /><strong>RESULTS: </strong>During the 30-month period, 1324 Mayo Clinic patients were patch tested with a standard series of allergens (mean, 60 allergens), whereas the NACDG standard series during this period included 50 allergens. Overall, 917 patients (69.3%) had at least one positive reaction and 606 patients (45.8%) had two or more positive reactions. The 10 allergens used both by Mayo Clinic and by the NACDG that most frequently caused positive reactions were nickel sulfate hexahydrate, balsam of Peru (Myroxylon pereirae), neomycin sulfate, cobalt chloride, fragrance mix, potassium dichromate (0.25%), thimerosal, bacitracin, formaldehyde, and glutaraldehyde. Statistically significant differences in positive reaction rates (P &lt; .05) were observed for 12 of the 43 allergens common to both Mayo Clinic and the NACDG.<br /><br /><strong>CONCLUSION: </strong>With large standard patch test series, one can identify commonly encountered and potentially relevant contact allergens.","Patch test results from the Mayo Clinic Contact Dermatitis Group, 1998-2000 Abs: <strong>BACKGROUND: </strong>Patch testing is a diagnostic tool for the evaluation of patients with suspected allergic contact dermatitis. A standard series of allergens similar to that used by the North American Contact Dermatitis Group (NACDG) is used at Mayo Clinic.<br /><br /><strong>OBJECTIVE: </strong>Our aim was to report the results of patch testing with a standard series at Mayo Clinic from July 1, 1998, to Dec 31, 2000 and to compare our findings with those of the NACDG during the same period.<br /><br /><strong>METHODS: </strong>The results of patch testing with the standard series at Mayo Clinic were examined. Positive reaction rates were compared between Mayo Clinic and the NACDG.<br /><br /><strong>RESULTS: </strong>During the 30-month period, 1324 Mayo Clinic patients were patch tested with a standard series of allergens (mean, 60 allergens), whereas the NACDG standard series during this period included 50 allergens. Overall, 917 patients (69.3%) had at least one positive reaction and 606 patients (45.8%) had two or more positive reactions. The 10 allergens used both by Mayo Clinic and by the NACDG that most frequently caused positive reactions were nickel sulfate hexahydrate, balsam of Peru (Myroxylon pereirae), neomycin sulfate, cobalt chloride, fragrance mix, potassium dichromate (0.25%), thimerosal, bacitracin, formaldehyde, and glutaraldehyde. Statistically significant differences in positive reaction rates (P &lt; .05) were observed for 12 of the 43 allergens common to both Mayo Clinic and the NACDG.<br /><br /><strong>CONCLUSION: </strong>With large standard patch test series, one can identify commonly encountered and potentially relevant contact allergens."
1234306,Elbekai and  El-Kadi 2005,"The role of oxidative stress in the modulation of aryl hydrocarbon receptor-regulated genes by As3+, Cd2+, and Cr6+","Heavy metals alter the capacity of AhR ligands to induce the bioactivating phase I and the detoxifying phase II xenobiotic-metabolizing enzymes but the mechanism(s) remain unknown. In the present study, we evaluated the role of As(3+)-, Cd(2+)-, and Cr(6+)-induced oxidative stress on the expression of Cyp1a1, Nqo1, and Gst ya in Hepa 1c1c7 cells. Both Cd2+ and Cr6+, but not As3+, increased the production of ROS. However, all metals increased cellular GSH content and heme oxygenase-1 mRNA levels. Although all three metals inhibited the induction of Cyp1a1 activity by TCDD, Cyp1a1 mRNA levels were potentiated. When cellular GSH was depleted with buthionine-(S,R)-sulfoximine (BSO), Cyp1a1 mRNA expression was further potentiated whereas Cyp1a1 activity was further inhibited. In parallel, pretreatment with the antioxidant N-acetylcysteine (NAC) did not alter Cyp1a1 mRNA expression but completely abrogated the inhibition of Cyp1a1 activity induction by all three metals. On the other hand, all three metals, alone or in the presence of TCDD, enhanced Nqo1 and Gst ya mRNA levels and Nqo1 activity. These effects were potentiated in the presence of BSO and abrogated with NAC. Our data clearly show that As(3+)-, Cd(2+)-, and Cr(6+)-induced oxidative stress modulates Cyp1a1 at transcriptional and posttranscriptional levels but induces Nqo1 and Gst ya at the transcriptional level.","The role of oxidative stress in the modulation of aryl hydrocarbon receptor-regulated genes by As3+, Cd2+, and Cr6+ Abs: Heavy metals alter the capacity of AhR ligands to induce the bioactivating phase I and the detoxifying phase II xenobiotic-metabolizing enzymes but the mechanism(s) remain unknown. In the present study, we evaluated the role of As(3+)-, Cd(2+)-, and Cr(6+)-induced oxidative stress on the expression of Cyp1a1, Nqo1, and Gst ya in Hepa 1c1c7 cells. Both Cd2+ and Cr6+, but not As3+, increased the production of ROS. However, all metals increased cellular GSH content and heme oxygenase-1 mRNA levels. Although all three metals inhibited the induction of Cyp1a1 activity by TCDD, Cyp1a1 mRNA levels were potentiated. When cellular GSH was depleted with buthionine-(S,R)-sulfoximine (BSO), Cyp1a1 mRNA expression was further potentiated whereas Cyp1a1 activity was further inhibited. In parallel, pretreatment with the antioxidant N-acetylcysteine (NAC) did not alter Cyp1a1 mRNA expression but completely abrogated the inhibition of Cyp1a1 activity induction by all three metals. On the other hand, all three metals, alone or in the presence of TCDD, enhanced Nqo1 and Gst ya mRNA levels and Nqo1 activity. These effects were potentiated in the presence of BSO and abrogated with NAC. Our data clearly show that As(3+)-, Cd(2+)-, and Cr(6+)-induced oxidative stress modulates Cyp1a1 at transcriptional and posttranscriptional levels but induces Nqo1 and Gst ya at the transcriptional level."
1234304,Vasant et al. 2005,Non-enzymatic phosphorylation of bovine serum albumin by Cr(V) complexes: role in Cr(VI)-induced phosphorylation and toxicity,"Evidence for the non-enzymatic phosphorylation of bovine serum albumin (BSA) by sodium bis(2-ethyl-2-hydroxybutyrato)oxochromate(V), Na[CrVO(ehba)2], 1, sodium bis(2-hydroxy-2-methylbutyrato)oxochromate(V), Na[CrVO(hmba)2], 2 and potassium dichromate, K2Cr2O7, 3 in the presence of labeled adenosine-5'-triphosphate (ATP) under conditions of physiological pH is presented. Aggregation and extent of phosphorylation of BSA mediated by 1, 2 or 3 seems to increase with the concentration and time of incubation of the reaction mixture containing all the reactants. The [gamma-32P] label in ATP is incorporated into aggregates of BSA in the in vitro reaction of the protein with ATP in the presence of 1, 2 or 3. Phosphorylation of BSA by ATP in the absence of 1, 2 or 3 is negligible. Addition of EDTA reverses aggregation of protein and liberates partially the incorporated phosphate label. The stoichiometry of phosphorylation is found to be the highest and is equal to 12.25 mol PO4(3-)/mol BSA in the presence of 500 microM of 1, which decreases to 10.56 mol PO4(3-)/mol BSA after EDTA treatment. Resistance to the removal of phosphate label by EDTA increases with increase in time of incubation. Dialysis of phosphorylated BSA reverses the incorporated [gamma-(32)P] label only partially, indicating the formation of covalent links of phosphate groups to BSA. Evidence for the site of phosphorylation in the reaction mediated by 1, 2 or 3 being hydroxyl side groups of tyrosine and serine/threonine residues has been gained. Based on the results, a possibility that 1, 2 and 3 mimic the function of tyrosine and serine/threonine kinases has been invoked.","Non-enzymatic phosphorylation of bovine serum albumin by Cr(V) complexes: role in Cr(VI)-induced phosphorylation and toxicity Abs: Evidence for the non-enzymatic phosphorylation of bovine serum albumin (BSA) by sodium bis(2-ethyl-2-hydroxybutyrato)oxochromate(V), Na[CrVO(ehba)2], 1, sodium bis(2-hydroxy-2-methylbutyrato)oxochromate(V), Na[CrVO(hmba)2], 2 and potassium dichromate, K2Cr2O7, 3 in the presence of labeled adenosine-5'-triphosphate (ATP) under conditions of physiological pH is presented. Aggregation and extent of phosphorylation of BSA mediated by 1, 2 or 3 seems to increase with the concentration and time of incubation of the reaction mixture containing all the reactants. The [gamma-32P] label in ATP is incorporated into aggregates of BSA in the in vitro reaction of the protein with ATP in the presence of 1, 2 or 3. Phosphorylation of BSA by ATP in the absence of 1, 2 or 3 is negligible. Addition of EDTA reverses aggregation of protein and liberates partially the incorporated phosphate label. The stoichiometry of phosphorylation is found to be the highest and is equal to 12.25 mol PO4(3-)/mol BSA in the presence of 500 microM of 1, which decreases to 10.56 mol PO4(3-)/mol BSA after EDTA treatment. Resistance to the removal of phosphate label by EDTA increases with increase in time of incubation. Dialysis of phosphorylated BSA reverses the incorporated [gamma-(32)P] label only partially, indicating the formation of covalent links of phosphate groups to BSA. Evidence for the site of phosphorylation in the reaction mediated by 1, 2 or 3 being hydroxyl side groups of tyrosine and serine/threonine residues has been gained. Based on the results, a possibility that 1, 2 and 3 mimic the function of tyrosine and serine/threonine kinases has been invoked."
1234303,Zhu et al. 2006,Improving alachlor biodegradability by ferrate oxidation,"Alachlor can be recalcitrant when present at high concentrations in wastewater. Ferrate oxidation was used as a pretreatment to improve its biodegradability and was evaluated by monitoring alachlor elimination and removal of COD(Cr) (chemical oxygen demand determined by potassium dichromate) during the oxidation process up to a value compatible with biological treatment. Ferrate oxidation resulted in elimination of alachlor followed by degradation of its intermediates. High pH suppressed alachlor removal and COD(Cr) removal due to the low redox potential of ferrate ions. Although alachlor can be totally eliminated within 10 min under optimized conditions (alachlor, 40 mg l(-1); ferrate:alachlor molar ratio, 2; and pH 7.0), its complete mineralization cannot be achieved by ferrate oxidation alone. Alachlor solution treated by ferrate for 10 min inhibited an up-flow biotreatment with activated sludge. The biodegradability of ferrate-pretreated solution improved when the treatment was increased to 20 min, at the point of which BOD(5)/COD(Cr) ratio of the treated solution was increased to 0.87 from 0.35 after 10 min treatment. Under optimized conditions, ferrate oxidation for 20 min resulted in total elimination of alachlor, partial removal of COD(Cr) and the ferrate-treated solution could be effectively treated by the up-flow activated sludge process.","Improving alachlor biodegradability by ferrate oxidation Abs: Alachlor can be recalcitrant when present at high concentrations in wastewater. Ferrate oxidation was used as a pretreatment to improve its biodegradability and was evaluated by monitoring alachlor elimination and removal of COD(Cr) (chemical oxygen demand determined by potassium dichromate) during the oxidation process up to a value compatible with biological treatment. Ferrate oxidation resulted in elimination of alachlor followed by degradation of its intermediates. High pH suppressed alachlor removal and COD(Cr) removal due to the low redox potential of ferrate ions. Although alachlor can be totally eliminated within 10 min under optimized conditions (alachlor, 40 mg l(-1); ferrate:alachlor molar ratio, 2; and pH 7.0), its complete mineralization cannot be achieved by ferrate oxidation alone. Alachlor solution treated by ferrate for 10 min inhibited an up-flow biotreatment with activated sludge. The biodegradability of ferrate-pretreated solution improved when the treatment was increased to 20 min, at the point of which BOD(5)/COD(Cr) ratio of the treated solution was increased to 0.87 from 0.35 after 10 min treatment. Under optimized conditions, ferrate oxidation for 20 min resulted in total elimination of alachlor, partial removal of COD(Cr) and the ferrate-treated solution could be effectively treated by the up-flow activated sludge process."
1234302,Zhai et al. 2006,Catalytic kinetic spectrophotometry for the determination of trace amount of oxalic acid in biological samples with oxalic acid-rhodamine B-potassium dichromate system,"A new catalytic kinetic spectrophotometric method was proposed for determining trace oxalic acid based on the catalytic effect of oxalate on the oxidation of potassium dichromate with rhodamin B in 0.10 M of sulfuric acid. Good linearity is obtained over the concentration range 0.40-6.0 microg/mL of oxalic acid. After the reactions of the catalytic and non-catalytic systems were terminated by using 2.00 mL of 4 M sodium hydroxide solution, they can be stable for 3 h at room temperature. The apparent activation energy of the catalytic reaction is 12.44 kJ/mol. The effect of 50 coexisting substances was observed. The method was used to determine trace oxalic acid in tea, spinach and urine samples with satisfactory results.","Catalytic kinetic spectrophotometry for the determination of trace amount of oxalic acid in biological samples with oxalic acid-rhodamine B-potassium dichromate system Abs: A new catalytic kinetic spectrophotometric method was proposed for determining trace oxalic acid based on the catalytic effect of oxalate on the oxidation of potassium dichromate with rhodamin B in 0.10 M of sulfuric acid. Good linearity is obtained over the concentration range 0.40-6.0 microg/mL of oxalic acid. After the reactions of the catalytic and non-catalytic systems were terminated by using 2.00 mL of 4 M sodium hydroxide solution, they can be stable for 3 h at room temperature. The apparent activation energy of the catalytic reaction is 12.44 kJ/mol. The effect of 50 coexisting substances was observed. The method was used to determine trace oxalic acid in tea, spinach and urine samples with satisfactory results."
1234301,Sultan and  Hasnain 2005,Chromate reduction capability of a gram positive bacterium isolated from effluent of dying industry,,Chromate reduction capability of a gram positive bacterium isolated from effluent of dying industry Abs: 
1234298,Hilp 2006,Colour reactions of griseofulvin Ph. Eur. 2005 using hydrogen peroxide solution or bromate or iodate as oxidant instead of potassium dichromate,,Colour reactions of griseofulvin Ph. Eur. 2005 using hydrogen peroxide solution or bromate or iodate as oxidant instead of potassium dichromate Abs: 
1234297,Qi et al. 2006,Incorporation of flow injection analysis or capillary electrophoresis with resonance Rayleigh scattering detection for inorganic ion analysis,"Resonance Rayleigh scattering (RRS) has been explored as a detection (RRSD) technique for capillary electrophoresis (CE) or flow injection analysis (FIA) of inorganic ions. The detection was achieved through a scattering probe of ion-association complex formed from rhodamine B (Rh B) and iodine. The probe scatters strongly at 630 nm when oxidants such as Cr(2)O(7)(2-), MnO(4)(-) and ClO(-) present in a mixed solution of Rh B and iodide. The scattering disappears once iodine is reduced by reductants. Oxidant or reductant species in a sample can thus be detected by positive or negative RRS signal. To verify the RRSD, FIA-RRSD was first constructed and continuous measurement of testing samples containing Cr(2)O(7)(2-), MnO(4)(-) and/or ClO(-) was performed. The detection limits reached a level of decade nM and a linear range was found between peak height and concentration at the range of 0.255-2.04microM for Cr(2)O(7)(2-), 0.158-3.16microM for MnO(4)(-), and 1.18-9.43microM for ClO(-), with linear regression coefficients of all above 0.99. The run-to-run relative standard deviation of peak height was less than 3% (n=6). CE-RRSD was then set up and studied, using a capillary of 75microm i.d.x33cm filled with a running buffer of 50mM citrate and 25mM Tris (pH 3.32) and worked under -12kV at room temperature. The CE eluent was at-line conducted into a stream of rhodamine B and iodine flowing inner a wide tube by plugging the capillary outlet into the wide tube. Different mixtures prepared from Cr(2)O(7)(2-), MnO(4)(-) and ClO(-) were successfully separated and detected by the CE-RRSD.","Incorporation of flow injection analysis or capillary electrophoresis with resonance Rayleigh scattering detection for inorganic ion analysis Abs: Resonance Rayleigh scattering (RRS) has been explored as a detection (RRSD) technique for capillary electrophoresis (CE) or flow injection analysis (FIA) of inorganic ions. The detection was achieved through a scattering probe of ion-association complex formed from rhodamine B (Rh B) and iodine. The probe scatters strongly at 630 nm when oxidants such as Cr(2)O(7)(2-), MnO(4)(-) and ClO(-) present in a mixed solution of Rh B and iodide. The scattering disappears once iodine is reduced by reductants. Oxidant or reductant species in a sample can thus be detected by positive or negative RRS signal. To verify the RRSD, FIA-RRSD was first constructed and continuous measurement of testing samples containing Cr(2)O(7)(2-), MnO(4)(-) and/or ClO(-) was performed. The detection limits reached a level of decade nM and a linear range was found between peak height and concentration at the range of 0.255-2.04microM for Cr(2)O(7)(2-), 0.158-3.16microM for MnO(4)(-), and 1.18-9.43microM for ClO(-), with linear regression coefficients of all above 0.99. The run-to-run relative standard deviation of peak height was less than 3% (n=6). CE-RRSD was then set up and studied, using a capillary of 75microm i.d.x33cm filled with a running buffer of 50mM citrate and 25mM Tris (pH 3.32) and worked under -12kV at room temperature. The CE eluent was at-line conducted into a stream of rhodamine B and iodine flowing inner a wide tube by plugging the capillary outlet into the wide tube. Different mixtures prepared from Cr(2)O(7)(2-), MnO(4)(-) and ClO(-) were successfully separated and detected by the CE-RRSD."
1234296,Inoue et al. 2006,Changes of physical and biochemical properties of Cryptosporidium oocysts with various storage conditions,"Physical and biochemical properties of Cryptosporidium parvum oocyst were examined after storage under various conditions. Oocyst-positive-fecal samples recovered from calves were either stored in a 2.0% potassium dichromate solution (Cr) or deionized water (W), or kept as a fecal pellet (P), and stored at 4 or 18 degrees C for a maximum of 100 days. When stored in Cr at 4 degrees C, the morphology of oocysts and their ability to withstand ultrasonics was not affected by the storing media or the storage period. However, when stored at 18 degees C as a fecal pellet, the specific gravity of the oocysts increased and a significant decrease in the oocysts resistance to ultrasonics occurred. These changes in oocyst properties may affect the performance of methods used to detect oocysts in water samples. When using the current test methods or when developing a new test method, it is important to take these factors into consideration.","Changes of physical and biochemical properties of Cryptosporidium oocysts with various storage conditions Abs: Physical and biochemical properties of Cryptosporidium parvum oocyst were examined after storage under various conditions. Oocyst-positive-fecal samples recovered from calves were either stored in a 2.0% potassium dichromate solution (Cr) or deionized water (W), or kept as a fecal pellet (P), and stored at 4 or 18 degrees C for a maximum of 100 days. When stored in Cr at 4 degrees C, the morphology of oocysts and their ability to withstand ultrasonics was not affected by the storing media or the storage period. However, when stored at 18 degees C as a fecal pellet, the specific gravity of the oocysts increased and a significant decrease in the oocysts resistance to ultrasonics occurred. These changes in oocyst properties may affect the performance of methods used to detect oocysts in water samples. When using the current test methods or when developing a new test method, it is important to take these factors into consideration."
1234293,Qian et al. 2006,Joint effects of microwave and chromium trioxide on root tip cells of Vicia faba,"The mutagenic effects of microwave and chromium trioxide (CrO(3)) on Vicia faba root tip were studied. Micronucleus assay and chromosomal aberration assay were used to determine the mitotic index, the micronucleus frequency and chromosomal aberration frequency of Vicia faba root tip cells induced by microwave and CrO(3). The results showed that the micronucleus frequency decreased, and that the mitotic index and chromosomal aberration frequency showed linear dose responses to CrO(3), in treatment of microwave for 5 s. In microwave of 25 s, the mitotic index decreased, the micronucleus frequency and chromosomal aberration frequency increased with increase of CrO(3) concentration. We concluded that microwave and CrO(3) had antagonistic effect on the mitotic index of Vicia faba root tip cells, but had synergetic effect on micronucleus frequency and chromosomal aberration frequency of Vicia faba root tip cells.","Joint effects of microwave and chromium trioxide on root tip cells of Vicia faba Abs: The mutagenic effects of microwave and chromium trioxide (CrO(3)) on Vicia faba root tip were studied. Micronucleus assay and chromosomal aberration assay were used to determine the mitotic index, the micronucleus frequency and chromosomal aberration frequency of Vicia faba root tip cells induced by microwave and CrO(3). The results showed that the micronucleus frequency decreased, and that the mitotic index and chromosomal aberration frequency showed linear dose responses to CrO(3), in treatment of microwave for 5 s. In microwave of 25 s, the mitotic index decreased, the micronucleus frequency and chromosomal aberration frequency increased with increase of CrO(3) concentration. We concluded that microwave and CrO(3) had antagonistic effect on the mitotic index of Vicia faba root tip cells, but had synergetic effect on micronucleus frequency and chromosomal aberration frequency of Vicia faba root tip cells."
1234292,Priester et al. 2006,Enhanced exopolymer production and chromium stabilization in Pseudomonas putida unsaturated biofilms,"Chromium-contaminated soils threaten surface and groundwater quality at many industrial sites. In vadose zones, indigenous bacteria can reduce Cr(VI) to Cr(III), but the subsequent fate of Cr(III) and the roles of bacterial biofilms are relatively unknown. To investigate, we cultured Pseudomonas putida, a model organism for vadose zone bioremediation, as unsaturated biofilms on membranes overlaying iron-deficient solid media either containing molecular dichromate from potassium dichromate (Cr-only treatment) or with deposits of solid, dichromate-coated hematite (Fe+Cr treatment) to simulate vadose zone conditions. Controls included iron-deficient solid medium and an Fe-only treatment using solid hematite deposits. Under iron-deficient conditions, chromium exposure resulted in lower cell yield and lower amounts of cellular protein and carbohydrate, but providing iron in the form of hematite overcame these toxic effects of Cr. For the Cr and Fe+Cr treatments, Cr(VI) was completely reduced to Cr(III) that accumulated on biofilm cells and extracellular polymeric substances (EPSs). Chromium exposure resulted in elevated extracellular carbohydrates, protein, DNA, and EPS sugars that were relatively enriched in N-acetyl-glucosamine, rhamnose, glucose, and mannose. The proportions of EPS protein and carbohydrate relative to intracellular pools suggested Cr toxicity-mediated cell lysis as the origin. However, DNA accumulated extracellularly in amounts far greater than expected from cell lysis, and Cr was liberated when extracted EPS was treated with DNase. These results demonstrate that Cr accumulation in unsaturated biofilms occurs with enzymatic reduction of Cr(VI), cellular lysis, cellular association, and extracellular DNA binding of Cr(III), which altogether can facilitate localized biotic stabilization of Cr in contaminated vadose zones.","Enhanced exopolymer production and chromium stabilization in Pseudomonas putida unsaturated biofilms Abs: Chromium-contaminated soils threaten surface and groundwater quality at many industrial sites. In vadose zones, indigenous bacteria can reduce Cr(VI) to Cr(III), but the subsequent fate of Cr(III) and the roles of bacterial biofilms are relatively unknown. To investigate, we cultured Pseudomonas putida, a model organism for vadose zone bioremediation, as unsaturated biofilms on membranes overlaying iron-deficient solid media either containing molecular dichromate from potassium dichromate (Cr-only treatment) or with deposits of solid, dichromate-coated hematite (Fe+Cr treatment) to simulate vadose zone conditions. Controls included iron-deficient solid medium and an Fe-only treatment using solid hematite deposits. Under iron-deficient conditions, chromium exposure resulted in lower cell yield and lower amounts of cellular protein and carbohydrate, but providing iron in the form of hematite overcame these toxic effects of Cr. For the Cr and Fe+Cr treatments, Cr(VI) was completely reduced to Cr(III) that accumulated on biofilm cells and extracellular polymeric substances (EPSs). Chromium exposure resulted in elevated extracellular carbohydrates, protein, DNA, and EPS sugars that were relatively enriched in N-acetyl-glucosamine, rhamnose, glucose, and mannose. The proportions of EPS protein and carbohydrate relative to intracellular pools suggested Cr toxicity-mediated cell lysis as the origin. However, DNA accumulated extracellularly in amounts far greater than expected from cell lysis, and Cr was liberated when extracted EPS was treated with DNase. These results demonstrate that Cr accumulation in unsaturated biofilms occurs with enzymatic reduction of Cr(VI), cellular lysis, cellular association, and extracellular DNA binding of Cr(III), which altogether can facilitate localized biotic stabilization of Cr in contaminated vadose zones."
1234291,Paradisi et al. 2006,Kaposi's varicelliform eruption complicating allergic contact dermatitis,,Kaposi's varicelliform eruption complicating allergic contact dermatitis Abs: 
1234290,Nair et al. 2006,Synthesis of nanocrystalline La(Ca)CrO3 through a novel gel combustion process and its characterization,"La(Ca)CrO3 (LCC) powders have been prepared through a novel gel combustion route using metal nitrates as oxidizers and ethylene diamine tetraacetic acid (EDTA) as a fuel. The process involves the combustion of a viscous gel obtained through mixed metal nitrate-EDTA solution. The effect of amount of EDTA used in the process on the nature of combustion reaction, phase formation, and densification has been studied. It was found that use of the fuel-rich precursor facile in controlling the reaction, which in turn helps in the scale up of the batch size. The calcination of the fuel-rich gel precursor at 650 degrees C resulted in the well-crystalline LCC along with a small amount of calcium chromate as a secondary phase. The HRSEM studies on the powder showed agglomerated nanoparticles. The average agglomerate size was found to be 0.54 microm. The cold pressing and sintering of the calcined powder at 1250 degrees C resulted in the mono-phasic La0.70Ca0.30CrO3 with 94% of its theoretical density. The sintered sample exhibited conductivity of 51 S/cm at 1000 degrees C. The average linear thermal expansion coefficient was found to be 10.3 x 10(-6) degrees C(-1).","Synthesis of nanocrystalline La(Ca)CrO3 through a novel gel combustion process and its characterization Abs: La(Ca)CrO3 (LCC) powders have been prepared through a novel gel combustion route using metal nitrates as oxidizers and ethylene diamine tetraacetic acid (EDTA) as a fuel. The process involves the combustion of a viscous gel obtained through mixed metal nitrate-EDTA solution. The effect of amount of EDTA used in the process on the nature of combustion reaction, phase formation, and densification has been studied. It was found that use of the fuel-rich precursor facile in controlling the reaction, which in turn helps in the scale up of the batch size. The calcination of the fuel-rich gel precursor at 650 degrees C resulted in the well-crystalline LCC along with a small amount of calcium chromate as a secondary phase. The HRSEM studies on the powder showed agglomerated nanoparticles. The average agglomerate size was found to be 0.54 microm. The cold pressing and sintering of the calcined powder at 1250 degrees C resulted in the mono-phasic La0.70Ca0.30CrO3 with 94% of its theoretical density. The sintered sample exhibited conductivity of 51 S/cm at 1000 degrees C. The average linear thermal expansion coefficient was found to be 10.3 x 10(-6) degrees C(-1)."
1234289,Kirpnick-Sobol et al. 2006,Carcinogenic Cr(VI) and the nutritional supplement Cr(III) induce DNA deletions in yeast and mice,"Industrial Cr(VI) emissions contaminate drinking water sources across the U.S., and many people take Cr(III) nutritional supplements. Cr(VI) is a human pulmonary carcinogen, but whether it is carcinogenic in the drinking water is not known. Due to widespread human exposure, it is imperative to determine the carcinogenic potential of Cr(VI) and Cr(III). DNA deletions and other genome rearrangements are involved in carcinogenesis. We determined the effects of Cr(VI) as potassium dichromate and Cr(III) as chromium(III) chloride on the frequencies of DNA deletions measured with the deletion assay in Saccharomyces cerevisiae and the in vivo p(un) reversion assay in C57BL/6J p(un)/p(un) mice. Exposing yeast and mice via drinking water to Cr(VI) and Cr(III) significantly increased the frequency of DNA deletions. We quantified intracellular chromium concentrations in yeast and tissue chromium concentrations in mice after exposure. Surprisingly, this revealed that Cr(III) is a more potent inducer of DNA deletions than Cr(VI) once Cr(III) is absorbed. This study concludes that both the environmental contaminant Cr(VI) and the nutritional supplement Cr(III) increase DNA deletions in vitro and in vivo, when ingested via drinking water.","Carcinogenic Cr(VI) and the nutritional supplement Cr(III) induce DNA deletions in yeast and mice Abs: Industrial Cr(VI) emissions contaminate drinking water sources across the U.S., and many people take Cr(III) nutritional supplements. Cr(VI) is a human pulmonary carcinogen, but whether it is carcinogenic in the drinking water is not known. Due to widespread human exposure, it is imperative to determine the carcinogenic potential of Cr(VI) and Cr(III). DNA deletions and other genome rearrangements are involved in carcinogenesis. We determined the effects of Cr(VI) as potassium dichromate and Cr(III) as chromium(III) chloride on the frequencies of DNA deletions measured with the deletion assay in Saccharomyces cerevisiae and the in vivo p(un) reversion assay in C57BL/6J p(un)/p(un) mice. Exposing yeast and mice via drinking water to Cr(VI) and Cr(III) significantly increased the frequency of DNA deletions. We quantified intracellular chromium concentrations in yeast and tissue chromium concentrations in mice after exposure. Surprisingly, this revealed that Cr(III) is a more potent inducer of DNA deletions than Cr(VI) once Cr(III) is absorbed. This study concludes that both the environmental contaminant Cr(VI) and the nutritional supplement Cr(III) increase DNA deletions in vitro and in vivo, when ingested via drinking water."
1234287,Darwish et al. 2006,Application of inorganic oxidants to the spectrophotometric determination of ribavirin in bulk and capsules,"Eight spectrophotometric methods for determination of ribavirin have been developed and validated. These methods were based on the oxidation of the drug by different inorganic oxidants: ceric ammonium sulfate, potassium permanganate, ammonium molybdate, ammonium metavanidate, chromium trioxide, potassium dichromate, potassium iodate, and potassium periodate. The oxidation reactions were performed in perchloric acid medium for ceric ammonium sulfate and in sulfuric acid medium for the other reagents. With ceric ammonium sulfate and potassium permanganate, the concentration of ribavirin in its samples was determined by measuring the decrease in the absorption intensity of the colored reagents at 315 and 525 nm, respectively. With the other reagents, the concentration of ribavirin was determined by measuring the intensity of the developed colored reaction products at the wavelengths of maximum absorbance: 675, 780, 595, 595, 475, and 475 nm for reactions with ammonium molybdate, ammonium metavanidate, chromium trioxide, potassium dichromate, potassium iodate, and potassium periodate, respectively. Different variables affecting the reaction conditions were carefully studied and optimized. Under the optimum conditions, linear relationships with good correlation coefficients (0.9984-0.9998) were found between the absorbance readings and the concentrations of ribavirin in the range of 4-1400 microg/mL. The molar absorptivities were correlated with the oxidation potential of the oxidants used. The precision of the methods were satisfactory; the values of relative standard deviation did not exceed 1.64%. The proposed methods were successfully applied to the analysis of ribavirin in pure drug material and capsules with good accuracy and precision; the recovery values were 99.2-101.2 +/- 0.48-1.30%. The results obtained using the proposed spectrophotometric methods were comparable with those obtained with the official method stated in the United States Pharmacopeia.","Application of inorganic oxidants to the spectrophotometric determination of ribavirin in bulk and capsules Abs: Eight spectrophotometric methods for determination of ribavirin have been developed and validated. These methods were based on the oxidation of the drug by different inorganic oxidants: ceric ammonium sulfate, potassium permanganate, ammonium molybdate, ammonium metavanidate, chromium trioxide, potassium dichromate, potassium iodate, and potassium periodate. The oxidation reactions were performed in perchloric acid medium for ceric ammonium sulfate and in sulfuric acid medium for the other reagents. With ceric ammonium sulfate and potassium permanganate, the concentration of ribavirin in its samples was determined by measuring the decrease in the absorption intensity of the colored reagents at 315 and 525 nm, respectively. With the other reagents, the concentration of ribavirin was determined by measuring the intensity of the developed colored reaction products at the wavelengths of maximum absorbance: 675, 780, 595, 595, 475, and 475 nm for reactions with ammonium molybdate, ammonium metavanidate, chromium trioxide, potassium dichromate, potassium iodate, and potassium periodate, respectively. Different variables affecting the reaction conditions were carefully studied and optimized. Under the optimum conditions, linear relationships with good correlation coefficients (0.9984-0.9998) were found between the absorbance readings and the concentrations of ribavirin in the range of 4-1400 microg/mL. The molar absorptivities were correlated with the oxidation potential of the oxidants used. The precision of the methods were satisfactory; the values of relative standard deviation did not exceed 1.64%. The proposed methods were successfully applied to the analysis of ribavirin in pure drug material and capsules with good accuracy and precision; the recovery values were 99.2-101.2 +/- 0.48-1.30%. The results obtained using the proposed spectrophotometric methods were comparable with those obtained with the official method stated in the United States Pharmacopeia."
1234286,Emmanouil et al. 2006,Oxidative damage produced by Cr(VI) and repair in mussel (Mytilus edulis L.) gill,"This study has assessed DNA damage induced by oxidative stress and its subsequent repair in mussels. Gill was obtained from mussels collected from New Brighton, UK within 24 h and also after 1 month maintenance under laboratory conditions. The pro-oxidant sodium dichromate produced a statistically significant increase in DNA strand breaks (DSB) in these gill cells at both time points as measured by the COMET assay. The response was higher at 1 month in association with a higher concentration of GSH which is known to activate Cr(VI) producing reactive oxygen species. DSB were shown, through studies in wild type and OGG-1-null mouse fibroblasts, to be produced by repair enzymes in response to Cr(VI). In support of evidence for repair of oxidative DNA damage, we have also demonstrated for the first time repair activity in mussel gill towards 8-oxo-dG using an oligonucleotide cutting assay.","Oxidative damage produced by Cr(VI) and repair in mussel (Mytilus edulis L.) gill Abs: This study has assessed DNA damage induced by oxidative stress and its subsequent repair in mussels. Gill was obtained from mussels collected from New Brighton, UK within 24 h and also after 1 month maintenance under laboratory conditions. The pro-oxidant sodium dichromate produced a statistically significant increase in DNA strand breaks (DSB) in these gill cells at both time points as measured by the COMET assay. The response was higher at 1 month in association with a higher concentration of GSH which is known to activate Cr(VI) producing reactive oxygen species. DSB were shown, through studies in wild type and OGG-1-null mouse fibroblasts, to be produced by repair enzymes in response to Cr(VI). In support of evidence for repair of oxidative DNA damage, we have also demonstrated for the first time repair activity in mussel gill towards 8-oxo-dG using an oligonucleotide cutting assay."
1234285,Sathyanarayanan and  Ortega 2006,Effects of temperature and different food matrices on Cyclospora cayetanensis oocyst sporulation,"Effects of temperature on the sporulation of the parasite Cyclospora cayetanensis were studied in 2 food substrates, dairy and basil. Unsporulated Cyclospora oocysts were subjected to freezing and heating conditions for time periods ranging from 15 min to 1 wk. Oocysts were then removed from the food substrates and placed in 2.5% potassium dichromate for 2 wk to allow viable unsporulated oocysts to differentiate and fully sporulate, and to determine the percentage sporulation as an indicator of viability. Sporulation occurred when oocysts resuspended in dairy substrates were stored within 24 hr at -15 C. When oocysts were placed in water or basil, sporulation occurred after incubation for up to 2 days at -20 C, and up to 4 days at 37 C. Few oocysts sporulated when incubated for 1 hr at 50 C. Sporulation was not observed in basil leaves or water at -70 C, 70 C, and 100 C. Sporulation was not affected when incubated at 4 C and 23 C for up to 1 wk, which was the duration of the experiment in both of the tested substrates.","Effects of temperature and different food matrices on Cyclospora cayetanensis oocyst sporulation Abs: Effects of temperature on the sporulation of the parasite Cyclospora cayetanensis were studied in 2 food substrates, dairy and basil. Unsporulated Cyclospora oocysts were subjected to freezing and heating conditions for time periods ranging from 15 min to 1 wk. Oocysts were then removed from the food substrates and placed in 2.5% potassium dichromate for 2 wk to allow viable unsporulated oocysts to differentiate and fully sporulate, and to determine the percentage sporulation as an indicator of viability. Sporulation occurred when oocysts resuspended in dairy substrates were stored within 24 hr at -15 C. When oocysts were placed in water or basil, sporulation occurred after incubation for up to 2 days at -20 C, and up to 4 days at 37 C. Few oocysts sporulated when incubated for 1 hr at 50 C. Sporulation was not observed in basil leaves or water at -70 C, 70 C, and 100 C. Sporulation was not affected when incubated at 4 C and 23 C for up to 1 wk, which was the duration of the experiment in both of the tested substrates."
1234284,Sung et al. 2006,Development and validation of a capillary electrophoresis method for the determination of sulfate in effervescent tablets,"A suitable capillary electrophoresis (CE) method was developed and validated for sulfate anion determination in effervescent tablets of Digedryl. The large excess of other ions in the matrix (i.e. excipients) constituted the main difficulty of this method's development. So an original analytical procedure for both the conditioning and rinsing of the capillary was purposed including a running electrolyte constituted by boric acid 20 mM and hexamethonium dibromide 0.75 mM at pH 8.00. Separation was carried out on a 60.2 cm (50 cm to the detector) x 0.75 microm i.d. fused-silica capillary at a potential of -29 kV and 35 degrees C. Indirect UV detection was performed at a wavelength of 254 nm using a background electrolyte containing potassium chromate. Nitrate anion was used as an internal standard for quantification. This CE method was validated in terms of selectivity, linearity, accuracy and precision.","Development and validation of a capillary electrophoresis method for the determination of sulfate in effervescent tablets Abs: A suitable capillary electrophoresis (CE) method was developed and validated for sulfate anion determination in effervescent tablets of Digedryl. The large excess of other ions in the matrix (i.e. excipients) constituted the main difficulty of this method's development. So an original analytical procedure for both the conditioning and rinsing of the capillary was purposed including a running electrolyte constituted by boric acid 20 mM and hexamethonium dibromide 0.75 mM at pH 8.00. Separation was carried out on a 60.2 cm (50 cm to the detector) x 0.75 microm i.d. fused-silica capillary at a potential of -29 kV and 35 degrees C. Indirect UV detection was performed at a wavelength of 254 nm using a background electrolyte containing potassium chromate. Nitrate anion was used as an internal standard for quantification. This CE method was validated in terms of selectivity, linearity, accuracy and precision."
1234283,Watanabe et al. 2006,Chromium(VI) as a novel MRI contrast agent for cerebral white matter: preliminary results in mouse brain in vivo,"This work demonstrates that intraventricular microinjections of a low dose of potassium dichromate (0.4 microL of 10 mM solution) yield a specific contrast enhancement of white matter (WM) tracts in T1-weighted 3D MRI of mouse brain in vivo. Pronounced and persistent signal increases (40-100% at 24 hr after injection) were observed in the corpus callosum, anterior commissure, fornix, and stria medullaris, as well as in the mammillothalamic tract and fasciculus retroflexus. These results suggest that the extracellular diffusion of diamagnetic chromium(VI) (Cr(VI)) after injection is followed by a tissue-specific reduction to paramagnetic Cr(V) and (III), which relies predominantly on the oxidation of myelin lipids. Because Cr(VI)-induced contrast leads to only a mild unspecific enhancement (10-20%) of gray matter (GM) structures, such as the hippocampal formation, the method reveals novel information that differs from that obtainable using other paramagnetic ions, such as manganese.","Chromium(VI) as a novel MRI contrast agent for cerebral white matter: preliminary results in mouse brain in vivo Abs: This work demonstrates that intraventricular microinjections of a low dose of potassium dichromate (0.4 microL of 10 mM solution) yield a specific contrast enhancement of white matter (WM) tracts in T1-weighted 3D MRI of mouse brain in vivo. Pronounced and persistent signal increases (40-100% at 24 hr after injection) were observed in the corpus callosum, anterior commissure, fornix, and stria medullaris, as well as in the mammillothalamic tract and fasciculus retroflexus. These results suggest that the extracellular diffusion of diamagnetic chromium(VI) (Cr(VI)) after injection is followed by a tissue-specific reduction to paramagnetic Cr(V) and (III), which relies predominantly on the oxidation of myelin lipids. Because Cr(VI)-induced contrast leads to only a mild unspecific enhancement (10-20%) of gray matter (GM) structures, such as the hippocampal formation, the method reveals novel information that differs from that obtainable using other paramagnetic ions, such as manganese."
1234282,Liu et al. 2006,Resonance Rayleigh scattering method for the determination of cationic surfactants with chromium(VI)-iodide system,"A method for detecting and identifying cationic surfactant in some chemical samples for daily use that include Head &amp; Shoulder Ampoule and Slek Shower Lotion has been developed. In an acid medium, chromium(VI) oxidizes I(-) to produce I(2), I(2) binds excess of I(-) to form I(3)(-), and I(3)(-) can further react with a cationic surfactant (CS) (such as cetyldimethyl benzylammonium chloride (CDBAC), Zephiramine (Zeph), cetylpyridinium bromide (CPB), tetradecyl pyridinium bromide (TPB) and cetyltrimethylammonium bromide (CTAB)) to form ion-association complexes [CS][I(3)]. This results in a significant enhancement of resonance Rayleigh scattering (RRS) and appearance of new RRS spectra. The RRS spectral characteristics of the ion-association complexes, the influencing factors and the optimum conditions of the reactions have been investigated. The intensities of RRS are directly proportional to the concentration of CS. CS in samples are collected using a treated anion exchange column and subsequently complexed by I(3)(-); then the RRS intensities of CS complex are determined at 495 nm. The reactions have high sensitivities, and their detection limits are 7.05 - 9.62 ng/mL for different CS. The effects of foreign substances are investigated and the results show that the method has good selectivity.","Resonance Rayleigh scattering method for the determination of cationic surfactants with chromium(VI)-iodide system Abs: A method for detecting and identifying cationic surfactant in some chemical samples for daily use that include Head &amp; Shoulder Ampoule and Slek Shower Lotion has been developed. In an acid medium, chromium(VI) oxidizes I(-) to produce I(2), I(2) binds excess of I(-) to form I(3)(-), and I(3)(-) can further react with a cationic surfactant (CS) (such as cetyldimethyl benzylammonium chloride (CDBAC), Zephiramine (Zeph), cetylpyridinium bromide (CPB), tetradecyl pyridinium bromide (TPB) and cetyltrimethylammonium bromide (CTAB)) to form ion-association complexes [CS][I(3)]. This results in a significant enhancement of resonance Rayleigh scattering (RRS) and appearance of new RRS spectra. The RRS spectral characteristics of the ion-association complexes, the influencing factors and the optimum conditions of the reactions have been investigated. The intensities of RRS are directly proportional to the concentration of CS. CS in samples are collected using a treated anion exchange column and subsequently complexed by I(3)(-); then the RRS intensities of CS complex are determined at 495 nm. The reactions have high sensitivities, and their detection limits are 7.05 - 9.62 ng/mL for different CS. The effects of foreign substances are investigated and the results show that the method has good selectivity."
1234281,Sarma et al. 2006,Effect of cadmium and chromium toxicity on the demography and population growth of Brachionus calyciflonrs and Brachionus patulus (Rotifera),"This paper reports on the assessment of the effect of Cd+2 and Cr+6 to the rotifers Brachionus calyciflorus and B. patulus using life table demography and population growth. Based on acute toxicity tests, cadmium was nearly 100 times more toxic than chromium for both the rotifer species. Age-specific fecundity curves of both the brachionids showed increased offspring beyond the age of 4 days and after that the production nearly stabilized for about 10 days and later declined. At any given treatment, B. calyciflorus had the higher rate of offspring production than B. patulus. For any given rotifer, increased metal concentration (Cd or Cr) resulted in decreased offspring production. While chromium at a concentration of 8.0 mg L(-1), permitted reproduction in B. calyciflorus, the egg production of B. patulus was inhibited at half that level (4.0 mg L(-1)). Cd at concentrations as low as 0.056 mg L(-1) caused 10-30% reduction in survivorship and reproductive parameters of B. calyciflorus. The lowest chromium concentration chosen for B. calyciflorus (0.5 mg L(-1)) had, however, a lower impact (2-22%) on the life history variables. Corresponding values of life history variables for B. patulus at the lowest Cd (0.0028 mg L(-1)) and Cr (0.25 mg L(-1)) concentrations varied greatly (2-40% and &lt; 1-24%, respectively). Compared to controls, both the rotifer species in Cd or Cr treatments had lower densities. In controls, B. calyciflorus reached a peak abundance of about 100 ind. mL(-1), while the corresponding value for B. patulus was slightly higher (120 ind. mL(-1)). The rate of population increase (r) derived from the population growth data varied from +0.42 to -0.40 depending on the concentration of the heavy metal in the medium.","Effect of cadmium and chromium toxicity on the demography and population growth of Brachionus calyciflonrs and Brachionus patulus (Rotifera) Abs: This paper reports on the assessment of the effect of Cd+2 and Cr+6 to the rotifers Brachionus calyciflorus and B. patulus using life table demography and population growth. Based on acute toxicity tests, cadmium was nearly 100 times more toxic than chromium for both the rotifer species. Age-specific fecundity curves of both the brachionids showed increased offspring beyond the age of 4 days and after that the production nearly stabilized for about 10 days and later declined. At any given treatment, B. calyciflorus had the higher rate of offspring production than B. patulus. For any given rotifer, increased metal concentration (Cd or Cr) resulted in decreased offspring production. While chromium at a concentration of 8.0 mg L(-1), permitted reproduction in B. calyciflorus, the egg production of B. patulus was inhibited at half that level (4.0 mg L(-1)). Cd at concentrations as low as 0.056 mg L(-1) caused 10-30% reduction in survivorship and reproductive parameters of B. calyciflorus. The lowest chromium concentration chosen for B. calyciflorus (0.5 mg L(-1)) had, however, a lower impact (2-22%) on the life history variables. Corresponding values of life history variables for B. patulus at the lowest Cd (0.0028 mg L(-1)) and Cr (0.25 mg L(-1)) concentrations varied greatly (2-40% and &lt; 1-24%, respectively). Compared to controls, both the rotifer species in Cd or Cr treatments had lower densities. In controls, B. calyciflorus reached a peak abundance of about 100 ind. mL(-1), while the corresponding value for B. patulus was slightly higher (120 ind. mL(-1)). The rate of population increase (r) derived from the population growth data varied from +0.42 to -0.40 depending on the concentration of the heavy metal in the medium."
1234278,Sankaramanivel et al. 2006,"Effect of chromium on vertebrae, femur and calvaria of adult male rats","Alloys of chromium have a long history of success in the surgical treatment of many orthopaedic defects. Nonetheless, prostheses loosening are commonly found around arthoplasties due to corrosion of metals. On this basis, it is hypothesized that chromium accumulation interferes with remodeling of bone. The present study aims to analyse the toxic effects of chromium on bone phosphatases in various regions of the bone in rats. Rats were treated with chromium intraperitoneally (0.5 mg/kg) in the form of potassium dichromate for 5 days. The accumulation of chromium is approximately 5.2-fold in the vertebrae, 8.9-fold in the femur and 8.7-fold in the calvaria, when compared to control. Chromium administration significantly reduced the activity of enzymes, eg, alkaline phosphatase (ALP) and tartrate-resistant acid phosphatase (TRAP). The study revealed a significant increase in the concentration of calcium, altered bone formation rate and bone morphology in the femur, vertebrae and calvaria. The interesting findings of the current study suggest altered bone turnover.","Effect of chromium on vertebrae, femur and calvaria of adult male rats Abs: Alloys of chromium have a long history of success in the surgical treatment of many orthopaedic defects. Nonetheless, prostheses loosening are commonly found around arthoplasties due to corrosion of metals. On this basis, it is hypothesized that chromium accumulation interferes with remodeling of bone. The present study aims to analyse the toxic effects of chromium on bone phosphatases in various regions of the bone in rats. Rats were treated with chromium intraperitoneally (0.5 mg/kg) in the form of potassium dichromate for 5 days. The accumulation of chromium is approximately 5.2-fold in the vertebrae, 8.9-fold in the femur and 8.7-fold in the calvaria, when compared to control. Chromium administration significantly reduced the activity of enzymes, eg, alkaline phosphatase (ALP) and tartrate-resistant acid phosphatase (TRAP). The study revealed a significant increase in the concentration of calcium, altered bone formation rate and bone morphology in the femur, vertebrae and calvaria. The interesting findings of the current study suggest altered bone turnover."
1234276,Corazza et al. 2006,Allergic contact dermatitis due to orthopedic shoes and a prosthesis for an amputated foot,,Allergic contact dermatitis due to orthopedic shoes and a prosthesis for an amputated foot Abs: 
1234275,Kang and  Wang 2006,Influence of chemical oxygen demand concentrations on anaerobic ammonium oxidation by granular sludge from EGSB reactor,"<strong>OBJECTIVE: </strong>To investigate the effect of chemical oxygen demand (COD) concentrations on the anaerobic ammonium oxidation (ANAMMOX).<br /><br /><strong>METHODS: </strong>An Expanded Granular Sludge Bed (EGSB) reactor was used to cultivate the granular sludge and to perform the ANAMMOX reaction in the bench scale experiment. NH4(+)-N and NO2(-)-N were measured by using colorimetric method. NO3(-)-N was analyzed by using the UV spectrophotometric method. COD measurement was based on digestion with potassium dichromate in concentrated sulphuric acid.<br /><br /><strong>RESULTS: </strong>When the COD concentrations in the reactors were 0 mg/L, 200 mg/L, 350 mg/L, and 550 mg/L, respectively, the NH4(+)-N removal efficiency was 12.5%, 14.2%, 14.3%, and 23.7%; the removal amount of NO2(-)-N was almost the same; the nitrate removal efficiency was 16.8%, 94.5%, 86.6%, and 84.2% and TN removal efficiency was 16.3%, 50.7%, 46.9%, and 50.4%, moreover, the COD removal efficiency was 85%, 65.7%, and 60%; the COD removal rate was 27.42, 61.88, and 97.8 mg COD/(h x L).<br /><br /><strong>CONCLUSION: </strong>COD concentrations have a significant influence on anaerobic ammonium oxidation by granular sludge.","Influence of chemical oxygen demand concentrations on anaerobic ammonium oxidation by granular sludge from EGSB reactor Abs: <strong>OBJECTIVE: </strong>To investigate the effect of chemical oxygen demand (COD) concentrations on the anaerobic ammonium oxidation (ANAMMOX).<br /><br /><strong>METHODS: </strong>An Expanded Granular Sludge Bed (EGSB) reactor was used to cultivate the granular sludge and to perform the ANAMMOX reaction in the bench scale experiment. NH4(+)-N and NO2(-)-N were measured by using colorimetric method. NO3(-)-N was analyzed by using the UV spectrophotometric method. COD measurement was based on digestion with potassium dichromate in concentrated sulphuric acid.<br /><br /><strong>RESULTS: </strong>When the COD concentrations in the reactors were 0 mg/L, 200 mg/L, 350 mg/L, and 550 mg/L, respectively, the NH4(+)-N removal efficiency was 12.5%, 14.2%, 14.3%, and 23.7%; the removal amount of NO2(-)-N was almost the same; the nitrate removal efficiency was 16.8%, 94.5%, 86.6%, and 84.2% and TN removal efficiency was 16.3%, 50.7%, 46.9%, and 50.4%, moreover, the COD removal efficiency was 85%, 65.7%, and 60%; the COD removal rate was 27.42, 61.88, and 97.8 mg COD/(h x L).<br /><br /><strong>CONCLUSION: </strong>COD concentrations have a significant influence on anaerobic ammonium oxidation by granular sludge."
1234274,Kuljanac et al. 2006,Epicutaneous patch test results in patients with allergic contact dermatitis in Karlovac county--a retrospective survey,"During the 1994-2003 study period, patch testing was carried out in 1102 subjects (740 female and 362 male, mean age 39.8, range 7-81 years) suspected to have allergic contact dermatitis (ACD). Epicutaneous patch test with a standard series of contact allergens was made by the Institute of Immunology, Zagreb, Croatia, according to the Internationational Contact Dermatitis Research Group (ICDRG) rules. During the study period, 399 (36.2%) subjects with one or more positive tests were recorded, and 640 positive tests were observed. The most frequent allergens were nickel sulfate identified in 214 (33.4%), cobalt chloride in 64 (10%), fragrance mix in 60 (9.4%), wood tar in 47 (7.3%), potassium dichromate in 39 (6.1%), balsam of Peru in 29 (4.6%) and other allergens in 187 (29.2%) cases. According to the localization of ACD, hands as the most common site were involved in 535 (48.5%) cases, followed by the face in 167 (15.2%) and other locations in 400 (36.3%) cases. It is concluded that nickel is the principal allergen as the cause of ACD, mostly affecting women. The areas most frequently involved by ACD were the hands and face.","Epicutaneous patch test results in patients with allergic contact dermatitis in Karlovac county--a retrospective survey Abs: During the 1994-2003 study period, patch testing was carried out in 1102 subjects (740 female and 362 male, mean age 39.8, range 7-81 years) suspected to have allergic contact dermatitis (ACD). Epicutaneous patch test with a standard series of contact allergens was made by the Institute of Immunology, Zagreb, Croatia, according to the Internationational Contact Dermatitis Research Group (ICDRG) rules. During the study period, 399 (36.2%) subjects with one or more positive tests were recorded, and 640 positive tests were observed. The most frequent allergens were nickel sulfate identified in 214 (33.4%), cobalt chloride in 64 (10%), fragrance mix in 60 (9.4%), wood tar in 47 (7.3%), potassium dichromate in 39 (6.1%), balsam of Peru in 29 (4.6%) and other allergens in 187 (29.2%) cases. According to the localization of ACD, hands as the most common site were involved in 535 (48.5%) cases, followed by the face in 167 (15.2%) and other locations in 400 (36.3%) cases. It is concluded that nickel is the principal allergen as the cause of ACD, mostly affecting women. The areas most frequently involved by ACD were the hands and face."
1234273,Cemeli et al. 2006,Genotoxic and antigenotoxic properties of selenium compounds in the in vitro micronucleus assay with human whole blood lymphocytes and TK6 lymphoblastoid cells,"Selenium is known to possess both genotoxic and antigenotoxic properties. In the present study, we have evaluated the genotoxicity and antigenotoxicity of three selenium compounds (sodium selenate, sodium selenite and selenous acid) by measuring in vitro micronucleus induction. Assays were conducted in whole blood lymphocytes and in the TK6 lymphoblastoid cell line, with and without co-treatment with potassium dichromate, a known genotoxic compound. In general, the compounds were more active in TK6 cells than they were in blood lymphocytes. Only 1 microM selenous acid increased the frequency of binucleated cells containing micronuclei (BNMN) in blood lymphocytes, while all three selenium compounds increased BNMN in TK6 cells. In addition, combinations of selenous acid and potassium dichromate resulted in lower frequencies of BNMN than potassium dichromate alone in blood lymphocytes, while combinations of sodium selenate and potassium dichromate produced lower frequencies of BNMN than potassium dichromate alone in TK6 cells. The concentrations of selenium compounds that were used, in combination with the medium components and the biological physiology of the whole blood lymphocytes and TK6 cells, could have affected the redox potential of the compounds, switching the chemicals from a pro-oxidant to antioxidant status and vice-versa. The lower activities of the compounds in blood lymphocytes may be due to the protective effects of blood components. The results indicate that the genotoxic and antigenotoxic properties of selenium compounds are highly dependent upon the conditions under which they are evaluated.","Genotoxic and antigenotoxic properties of selenium compounds in the in vitro micronucleus assay with human whole blood lymphocytes and TK6 lymphoblastoid cells Abs: Selenium is known to possess both genotoxic and antigenotoxic properties. In the present study, we have evaluated the genotoxicity and antigenotoxicity of three selenium compounds (sodium selenate, sodium selenite and selenous acid) by measuring in vitro micronucleus induction. Assays were conducted in whole blood lymphocytes and in the TK6 lymphoblastoid cell line, with and without co-treatment with potassium dichromate, a known genotoxic compound. In general, the compounds were more active in TK6 cells than they were in blood lymphocytes. Only 1 microM selenous acid increased the frequency of binucleated cells containing micronuclei (BNMN) in blood lymphocytes, while all three selenium compounds increased BNMN in TK6 cells. In addition, combinations of selenous acid and potassium dichromate resulted in lower frequencies of BNMN than potassium dichromate alone in blood lymphocytes, while combinations of sodium selenate and potassium dichromate produced lower frequencies of BNMN than potassium dichromate alone in TK6 cells. The concentrations of selenium compounds that were used, in combination with the medium components and the biological physiology of the whole blood lymphocytes and TK6 cells, could have affected the redox potential of the compounds, switching the chemicals from a pro-oxidant to antioxidant status and vice-versa. The lower activities of the compounds in blood lymphocytes may be due to the protective effects of blood components. The results indicate that the genotoxic and antigenotoxic properties of selenium compounds are highly dependent upon the conditions under which they are evaluated."
1234270,Grillo and  Dulout 2006,Butylated hydroxytoluene does not protect Chinese hamster ovary cells from chromosomal damage induced by high-dose rate 192Ir irradiation,"Previous reports showed the protective effect of the synthetic antioxidant butylated hydroxytoluene (BHT) against the chromosomal damage induced by bleomycin (BLM), cadmium chloride and potassium dichromate. To test the hypothesis that this effect was exerted by inhibition and/or scavenging of reactive oxygen species (ROS), the effect of BHT on the chromosomal damage induced by a high dose-rate gamma rays (HDR (192)Ir). Experiments were carried out by irradiating G(1) CHO cells with nominal doses of 1, 2 or 3 Gy. BHT (doses of 1.0, 2.5 or 5.0 microg/ml) was added to the culture immediately before or immediately after irradiation. Cells were then incubated in the presence of BHT for 13 h until harvesting and fixation. Results obtained showed that BHT did not decrease the chromosomal damage induced by radiation in any consistent fashion. On the contrary, in cells post-treated with 5.0 microg/ml of BHT the yield of chromosomal aberrations increased in several experimental points. These results with ionizing radiation suggest that the previous observed protective effects of BHT on the chromosomal damage induced by chemical genotoxicants may not be mediated solely through the scavenging or inactivating reactive oxidative species. The decrease of the yield of chromosomal damage induced by BLM could be due to the union of BHT with a metallic ion, in this case Fe (II), required for the activation of BLM. In the same way, the protective effect of BHT on the chromosomal damage induced by cadmium chloride and potassium dichromate could be due to the decrease of the effective dose of both salts in the cell through the chelation of the cations by BHT.","Butylated hydroxytoluene does not protect Chinese hamster ovary cells from chromosomal damage induced by high-dose rate 192Ir irradiation Abs: Previous reports showed the protective effect of the synthetic antioxidant butylated hydroxytoluene (BHT) against the chromosomal damage induced by bleomycin (BLM), cadmium chloride and potassium dichromate. To test the hypothesis that this effect was exerted by inhibition and/or scavenging of reactive oxygen species (ROS), the effect of BHT on the chromosomal damage induced by a high dose-rate gamma rays (HDR (192)Ir). Experiments were carried out by irradiating G(1) CHO cells with nominal doses of 1, 2 or 3 Gy. BHT (doses of 1.0, 2.5 or 5.0 microg/ml) was added to the culture immediately before or immediately after irradiation. Cells were then incubated in the presence of BHT for 13 h until harvesting and fixation. Results obtained showed that BHT did not decrease the chromosomal damage induced by radiation in any consistent fashion. On the contrary, in cells post-treated with 5.0 microg/ml of BHT the yield of chromosomal aberrations increased in several experimental points. These results with ionizing radiation suggest that the previous observed protective effects of BHT on the chromosomal damage induced by chemical genotoxicants may not be mediated solely through the scavenging or inactivating reactive oxidative species. The decrease of the yield of chromosomal damage induced by BLM could be due to the union of BHT with a metallic ion, in this case Fe (II), required for the activation of BLM. In the same way, the protective effect of BHT on the chromosomal damage induced by cadmium chloride and potassium dichromate could be due to the decrease of the effective dose of both salts in the cell through the chelation of the cations by BHT."
1234269,Sagle et al. 2006,Direct and high resolution characterization of cytochrome c equilibrium folding,"Protein folding has emerged as a central problem in biophysics, and the equilibrium folding mechanism of cytochrome c (cyt c) has served as a model system. Unfortunately, the detailed characterization of both the folding process and of any intermediate that might be populated has been limited by the low structural and/or temporal resolution of the available techniques. Here, we report the use of a recently developed technique to study folding that is based on the site-selective incorporation of carbon-deuterium (C-D) bonds and their characterization by IR spectroscopy. Specifically, we synthesize and characterize the protein with deuterated residues spread throughout four structural motifs: (d3)Leu68 in the 60's helix, (d8)Lys72 and (d8)Lys73 in the 70's helix, (d8)Lys79, (d3)Met80, and (d3)Ala83 in the D-loop, and (d3)Leu94, (d3)Leu98, and (d3)Ala101 in the C-terminal helix. The data reveal correlated behavior of the residues within each structural motif, as well as between the residues of the 60's and C-terminal helices and between residues of the 70's helix and D-loop. Residues of the 70's helix and the D-loop are more stable than those within the 60's and C-terminal helices, although the former are more sensitive to added denaturant. The data also suggest that the hydrophobicity of the heme cofactor plays a central role in folding. These results contrast with those from previous H/D exchange studies and suggest that the low denaturant fluctuations observed in the H/D exchange experiments are not similar to those through which the protein actually unfolds. The inherently fast time scale of IR also allows us to characterize the folding intermediate, long thought to be present, but which has proven difficult to characterize by other techniques.","Direct and high resolution characterization of cytochrome c equilibrium folding Abs: Protein folding has emerged as a central problem in biophysics, and the equilibrium folding mechanism of cytochrome c (cyt c) has served as a model system. Unfortunately, the detailed characterization of both the folding process and of any intermediate that might be populated has been limited by the low structural and/or temporal resolution of the available techniques. Here, we report the use of a recently developed technique to study folding that is based on the site-selective incorporation of carbon-deuterium (C-D) bonds and their characterization by IR spectroscopy. Specifically, we synthesize and characterize the protein with deuterated residues spread throughout four structural motifs: (d3)Leu68 in the 60's helix, (d8)Lys72 and (d8)Lys73 in the 70's helix, (d8)Lys79, (d3)Met80, and (d3)Ala83 in the D-loop, and (d3)Leu94, (d3)Leu98, and (d3)Ala101 in the C-terminal helix. The data reveal correlated behavior of the residues within each structural motif, as well as between the residues of the 60's and C-terminal helices and between residues of the 70's helix and D-loop. Residues of the 70's helix and the D-loop are more stable than those within the 60's and C-terminal helices, although the former are more sensitive to added denaturant. The data also suggest that the hydrophobicity of the heme cofactor plays a central role in folding. These results contrast with those from previous H/D exchange studies and suggest that the low denaturant fluctuations observed in the H/D exchange experiments are not similar to those through which the protein actually unfolds. The inherently fast time scale of IR also allows us to characterize the folding intermediate, long thought to be present, but which has proven difficult to characterize by other techniques."
1234268,Magen et al. 2006,Sensitizations to allergens of TRUE test in 864 consecutive eczema patients in Israel,"The TRUE test is a widespread diagnostic tool for initial patch testing of patients with contact dermatitis (CD). From 2002 to 2005, 864 patients with eczema were patch-tested using TRUE test in one Israeli allergology clinic. 547 (63.3%) patients were female and 317 (36.7%) were male. 346 (40%) patients had &gt; or =1 positive patch test reactions. The most common allergens were nickel sulfate for 114 (13.2%) patients, potassium dichromate 111 (12.8%), fragrance mix 59 (6.8%), cobalt chloride 12 (1.4%), ethylenediamine dihydrochloride 11 (1.3%), epoxy resin 11 (1.3%), balsam of Peru 9 (1.0%), carba mix 7 (0.8%), thiomersal 6 (0.7%), wool alcohol 5 (0.6%), black rubber (PPD) mix 5 (0.6%), neomycin 4 (0.5%); Kathon CG, Colophony and Quaternium 15 - each 2 (0.2%), other allergens - each 1 (0.1%). In male patients, carba mix, black rubber (PPD) mix and epoxy resin sensitivity was more frequent, whereas nickel sulfate, fragrance mix, ethylenediamine dihydrochloride and cobalt chloride sensitivity was significantly more frequent in female patients. Our results are in general agreement with previously published reports, excluding the low sensitivity rates to cobalt, which maybe is missed by TRUE test.","Sensitizations to allergens of TRUE test in 864 consecutive eczema patients in Israel Abs: The TRUE test is a widespread diagnostic tool for initial patch testing of patients with contact dermatitis (CD). From 2002 to 2005, 864 patients with eczema were patch-tested using TRUE test in one Israeli allergology clinic. 547 (63.3%) patients were female and 317 (36.7%) were male. 346 (40%) patients had &gt; or =1 positive patch test reactions. The most common allergens were nickel sulfate for 114 (13.2%) patients, potassium dichromate 111 (12.8%), fragrance mix 59 (6.8%), cobalt chloride 12 (1.4%), ethylenediamine dihydrochloride 11 (1.3%), epoxy resin 11 (1.3%), balsam of Peru 9 (1.0%), carba mix 7 (0.8%), thiomersal 6 (0.7%), wool alcohol 5 (0.6%), black rubber (PPD) mix 5 (0.6%), neomycin 4 (0.5%); Kathon CG, Colophony and Quaternium 15 - each 2 (0.2%), other allergens - each 1 (0.1%). In male patients, carba mix, black rubber (PPD) mix and epoxy resin sensitivity was more frequent, whereas nickel sulfate, fragrance mix, ethylenediamine dihydrochloride and cobalt chloride sensitivity was significantly more frequent in female patients. Our results are in general agreement with previously published reports, excluding the low sensitivity rates to cobalt, which maybe is missed by TRUE test."
1234267,Yazar et al. 2006,[Isospora belli infection in a patient with a renal transplant],"Isospora belli infection is frequent in immunosuppressed patients and can cause wasting diarrhea. We present the first isosporiosis case in a renal transplant recipient from Turkey. The 25-year old male patient who had had a renal transplantation due to renal failure and had received immunosuppressive therapy presented at the hospital complaining of weakness, nausea, vomiting and diarrhea that had lasted for 15 days. Isospora belli oocysts were detected in stool samples by direct microscopy, modified Ziehl-Neelsen staining methods and autofluorescence technique. Oocysts in the stool samples were also sporulated in 2.5% potassium dichromate and the sporulated oocysts were seen microscopically. The patient was treated with co-trimoxazole (trimethoprim 160 mg, sulphamethoxazole 800 mg) every 12 hours for seven days, with elimination of the symptoms at this time. After this, Isospora belli oocysts were no longer seen in stool samples.","[Isospora belli infection in a patient with a renal transplant] Abs: Isospora belli infection is frequent in immunosuppressed patients and can cause wasting diarrhea. We present the first isosporiosis case in a renal transplant recipient from Turkey. The 25-year old male patient who had had a renal transplantation due to renal failure and had received immunosuppressive therapy presented at the hospital complaining of weakness, nausea, vomiting and diarrhea that had lasted for 15 days. Isospora belli oocysts were detected in stool samples by direct microscopy, modified Ziehl-Neelsen staining methods and autofluorescence technique. Oocysts in the stool samples were also sporulated in 2.5% potassium dichromate and the sporulated oocysts were seen microscopically. The patient was treated with co-trimoxazole (trimethoprim 160 mg, sulphamethoxazole 800 mg) every 12 hours for seven days, with elimination of the symptoms at this time. After this, Isospora belli oocysts were no longer seen in stool samples."
1234266,Mohammed and  Agard 2006,"Comparative sensitivity of three tropical cladoceran species (Diaphanosoma brachyurum, Ceriodaphnia rigaudii and Moinodaphnia macleayi) to six chemicals","The toxicities of six chemicals (cadmium chloride, potassium dichromate, sodium dodecyl sulfate, potassium chloride, Tritox X-100 and copper (II) sulphate) was determined for three tropical freshwater cladoceran, Moinodaphnia macleayi, Ceriodaphnia rigaudii and Diaphanosoma brachyurum. The data was subsequently used to compare the relative sensitivity of the three species. Relative sensitivities were determined by comparing the 48-hour LC50 values using an independent t-test and interspecies correlation. Potassium dichromate was the most toxic compound tested, while potassium chloride was the least toxic to all three species. The 48 h LC50 values for D. brachyurum ranged from 0.003 mg/L to 30.4 mg/L; M. macleayi LC50 values ranged from 0.003 mg/L to 30.1 mg/L whereas for C. rigaudii the values ranging between 0.002 mg/L to 21.1 mg/L. The LC50 values for C. rigaudii was significantly less (P &lt; 0.05) than M. macleayi for five of the compounds tested, whereas for D. brachyurum it was significantly (P &lt; 0.05) less than four of the compounds tested. The interspecies correlation also suggested that C. rigaudii and M. macleayi were more similar in sensitivity (R2 = 0.96) to each other than D. brachyurum (R2 = 0.91 with M. macleayi, and R2 = 0.87 with C. rigaudii).","Comparative sensitivity of three tropical cladoceran species (Diaphanosoma brachyurum, Ceriodaphnia rigaudii and Moinodaphnia macleayi) to six chemicals Abs: The toxicities of six chemicals (cadmium chloride, potassium dichromate, sodium dodecyl sulfate, potassium chloride, Tritox X-100 and copper (II) sulphate) was determined for three tropical freshwater cladoceran, Moinodaphnia macleayi, Ceriodaphnia rigaudii and Diaphanosoma brachyurum. The data was subsequently used to compare the relative sensitivity of the three species. Relative sensitivities were determined by comparing the 48-hour LC50 values using an independent t-test and interspecies correlation. Potassium dichromate was the most toxic compound tested, while potassium chloride was the least toxic to all three species. The 48 h LC50 values for D. brachyurum ranged from 0.003 mg/L to 30.4 mg/L; M. macleayi LC50 values ranged from 0.003 mg/L to 30.1 mg/L whereas for C. rigaudii the values ranging between 0.002 mg/L to 21.1 mg/L. The LC50 values for C. rigaudii was significantly less (P &lt; 0.05) than M. macleayi for five of the compounds tested, whereas for D. brachyurum it was significantly (P &lt; 0.05) less than four of the compounds tested. The interspecies correlation also suggested that C. rigaudii and M. macleayi were more similar in sensitivity (R2 = 0.96) to each other than D. brachyurum (R2 = 0.91 with M. macleayi, and R2 = 0.87 with C. rigaudii)."
1234265,Suarez-Luque et al. 2006,Capillary zone electrophoresis method for the determination of inorganic anions and formic acid in honey,"A capillary zone electrophoresis method for the determination of inorganic anions and formic acid in honey samples was developed for the first time. The complete separation of chloride, nitrate, sulfate, phosphate, and formic acid was achieved with a simple electrolyte composed by 2 mM potassium dichromate as the carrier solution and background absorbance provider and 0.05 mM tetraethylenepentamine (TEPA) as electro-osmotic flow suppressor (pH 4.00). Injection was performed hydrostatically by elevating the sample at 10 cm for 10 s. The running voltage was -27 kV at 25 degrees C. Indirect UV absorption detection was achieved at 254 nm. The detection limit was in the range between 0.03 and 20 mg/kg, and the quantification limits ranged from 1.52 to 20.6 mg/kg. The calibration graphs were linear in the concentration range from the quantification limit to at least 2.5 g/kg for chloride, 0.25 g/kg for nitrate, 0.75 g/kg for sulfate, 1.50 g/kg for phosphate, and 0.75 g/kg for formic acid. Precision data in the honey samples analyzed showed repeatability and reproducibility relative standard deviations lower than 1.4 and 2.4% for migration time and lower than 1.8 and 4.3% for anion content, respectively. Recoveries of anions in honey samples analyzed ranged from 94.4 to 99.8%. Ten honey samples were analyzed to test the proposed method. Mean contents of 260.5, 3.93, 60.5, 139.4, and 209.3 mg/kg were found, respectively, for chloride, nitrate, sulfate, phosphate, and formic acid in analyzed honeys. These results agreed with literature data.","Capillary zone electrophoresis method for the determination of inorganic anions and formic acid in honey Abs: A capillary zone electrophoresis method for the determination of inorganic anions and formic acid in honey samples was developed for the first time. The complete separation of chloride, nitrate, sulfate, phosphate, and formic acid was achieved with a simple electrolyte composed by 2 mM potassium dichromate as the carrier solution and background absorbance provider and 0.05 mM tetraethylenepentamine (TEPA) as electro-osmotic flow suppressor (pH 4.00). Injection was performed hydrostatically by elevating the sample at 10 cm for 10 s. The running voltage was -27 kV at 25 degrees C. Indirect UV absorption detection was achieved at 254 nm. The detection limit was in the range between 0.03 and 20 mg/kg, and the quantification limits ranged from 1.52 to 20.6 mg/kg. The calibration graphs were linear in the concentration range from the quantification limit to at least 2.5 g/kg for chloride, 0.25 g/kg for nitrate, 0.75 g/kg for sulfate, 1.50 g/kg for phosphate, and 0.75 g/kg for formic acid. Precision data in the honey samples analyzed showed repeatability and reproducibility relative standard deviations lower than 1.4 and 2.4% for migration time and lower than 1.8 and 4.3% for anion content, respectively. Recoveries of anions in honey samples analyzed ranged from 94.4 to 99.8%. Ten honey samples were analyzed to test the proposed method. Mean contents of 260.5, 3.93, 60.5, 139.4, and 209.3 mg/kg were found, respectively, for chloride, nitrate, sulfate, phosphate, and formic acid in analyzed honeys. These results agreed with literature data."
1234264,Corazza et al. 2006,An unusual local reaction after microsclerotherapy with chromated glycerin,"A case of papular itching lesions after microsclerotherapy with chromated glycerin (CG) at a 72% concentration for telangiectases of the thighs is reported. Patch-test results were strongly positive for nickel sulfate (+++/+++) and thimerosal (++/++) whereas results were negative for the sclerosing agent CG 72% and glycerol (control). Intradermal injection of CG 72% in the thigh and intravascular injection of CG 72% into telangiectases of the knee produced erythematous papular itching lesions in about 5 to 6 hours. As a negative control, glycerol and sodium chloride 0.9% injected intradermically on the thigh did not cause any reaction. CG can elicit allergic reactions in patients who are sensitive to chromium and can cause new sensitizations to chromium. In our case, no positivity to potassium dichromate was observed.","An unusual local reaction after microsclerotherapy with chromated glycerin Abs: A case of papular itching lesions after microsclerotherapy with chromated glycerin (CG) at a 72% concentration for telangiectases of the thighs is reported. Patch-test results were strongly positive for nickel sulfate (+++/+++) and thimerosal (++/++) whereas results were negative for the sclerosing agent CG 72% and glycerol (control). Intradermal injection of CG 72% in the thigh and intravascular injection of CG 72% into telangiectases of the knee produced erythematous papular itching lesions in about 5 to 6 hours. As a negative control, glycerol and sodium chloride 0.9% injected intradermically on the thigh did not cause any reaction. CG can elicit allergic reactions in patients who are sensitive to chromium and can cause new sensitizations to chromium. In our case, no positivity to potassium dichromate was observed."
1234262,Onizuka et al. 2006,[A case of chrome asthma induced by exposure to the stone cutter dust],"The case of a forty-six year old, male patient with asthma caused by exposure to dust containing chrome is presented. When the patient was nineteen years old, he started working as a stonemason in a factory. He cut and ground stone with a stone-cutter to make statues and tombstones. Three years after staring to work, contact dermatitis was observed on his arms and hands. Within six years of work, he suffered from chronic coughing. After eight years, he experienced bronchial asthma attacks with wheezing and dyspnea. He had been exposed to dust for eight years before developing asthma. The symptoms increased gradually. He fell into severe asthma attacks causing unconsciousness and dyspnea. Several common therapies were not effective. The characteristics of his clinical course and occupational history suggested that the asthma must be caused by exposure to dust containing metal generated in the factory. Skin Patch Tests (SPT) were performed for cobalt, copper, iron, chrome, tin, and manganese salt. The result of the SPT indicated a strong positive result for potassium dichromate and positive for chromium sulfate, but did not show any indications in the control or for other metallic salt. Fluorescent X-ray analysis detected that chrome was present in the powder dust under the stone-cutter machine. However, the fluorescent X-ray analysis did not detect chrome in the stone materials. It was suggested that chrome must be contained in the metal dust generated from the steel cutter used to cut off and grind the stone. The metal component in the used cutter edge and the unused cutter edge were analyzed with electro-probe microanalyzer (EPMA). The result revealed that chrome was contained in the used, dull cutter edge and not in the new sharp cutter edge. Thus, the patient had been exposed to the dust containing chrome generated from part of the stainless steel of cutter. He had sensitized to chrome and this had caused the occupational chrome-asthma.","[A case of chrome asthma induced by exposure to the stone cutter dust] Abs: The case of a forty-six year old, male patient with asthma caused by exposure to dust containing chrome is presented. When the patient was nineteen years old, he started working as a stonemason in a factory. He cut and ground stone with a stone-cutter to make statues and tombstones. Three years after staring to work, contact dermatitis was observed on his arms and hands. Within six years of work, he suffered from chronic coughing. After eight years, he experienced bronchial asthma attacks with wheezing and dyspnea. He had been exposed to dust for eight years before developing asthma. The symptoms increased gradually. He fell into severe asthma attacks causing unconsciousness and dyspnea. Several common therapies were not effective. The characteristics of his clinical course and occupational history suggested that the asthma must be caused by exposure to dust containing metal generated in the factory. Skin Patch Tests (SPT) were performed for cobalt, copper, iron, chrome, tin, and manganese salt. The result of the SPT indicated a strong positive result for potassium dichromate and positive for chromium sulfate, but did not show any indications in the control or for other metallic salt. Fluorescent X-ray analysis detected that chrome was present in the powder dust under the stone-cutter machine. However, the fluorescent X-ray analysis did not detect chrome in the stone materials. It was suggested that chrome must be contained in the metal dust generated from the steel cutter used to cut off and grind the stone. The metal component in the used cutter edge and the unused cutter edge were analyzed with electro-probe microanalyzer (EPMA). The result revealed that chrome was contained in the used, dull cutter edge and not in the new sharp cutter edge. Thus, the patient had been exposed to the dust containing chrome generated from part of the stainless steel of cutter. He had sensitized to chrome and this had caused the occupational chrome-asthma."
1234261,Shaapan and  Ghazy 2007,Isolation of Toxoplasma gondii from horse meat in Egypt,"Portions of heart, liver, skeletal and diaphragmatic muscles obtained from 150 slaughtered horses at Giza-Zoo abattoir were used for bioassays in mice and cats. T. gondii tachyzoites were isolated successfully from the peritoneal exudates of the inoculated mice 6-8 days post inoculation with pooled horse tissues. Whereas, T. gondii tissue cysts containing bradyzoites were detected in the impression smears of mice brain on the 45th days or more post infection. The oocysts were detected in feces of cats 3-6 days post feeding on horse tissues containing tissue cysts. The oocysts became sporulated within 3-5 days in 2.5% Potassium dichromate. A total of 79 out of 150 horse meat samples were found to be infected with an incidence rate of 52.6 %. This is the first trial for isolation of T. gondii infective stages from horses in Egypt. Moreover, this study pointed out to the high infection rate of T. gondii in horse meat which may be considered as an important source of infection to wild zoo-animals in Egypt and humans in some countries if consumed raw or insufficiently cooked.","Isolation of Toxoplasma gondii from horse meat in Egypt Abs: Portions of heart, liver, skeletal and diaphragmatic muscles obtained from 150 slaughtered horses at Giza-Zoo abattoir were used for bioassays in mice and cats. T. gondii tachyzoites were isolated successfully from the peritoneal exudates of the inoculated mice 6-8 days post inoculation with pooled horse tissues. Whereas, T. gondii tissue cysts containing bradyzoites were detected in the impression smears of mice brain on the 45th days or more post infection. The oocysts were detected in feces of cats 3-6 days post feeding on horse tissues containing tissue cysts. The oocysts became sporulated within 3-5 days in 2.5% Potassium dichromate. A total of 79 out of 150 horse meat samples were found to be infected with an incidence rate of 52.6 %. This is the first trial for isolation of T. gondii infective stages from horses in Egypt. Moreover, this study pointed out to the high infection rate of T. gondii in horse meat which may be considered as an important source of infection to wild zoo-animals in Egypt and humans in some countries if consumed raw or insufficiently cooked."
1234260,Freireich-Astman et al. 2007,Standard patch test results in patients with contact dermatitis in Israel: age and sex differences,"Previous studies have shown that the prevalence of specific allergens varies by geographic area, population, age and sex. The objective of the present study was to determine the relative frequency of positive reactions to different sensitizers in Israeli patients with clinically suspected contact dermatitis (CD) and to identify possible sex and age differences. A total of 943 consecutive patients were tested for CD using the European standard patch test series. The most frequent allergen was nickel sulfate followed by potassium dichromate and fragrance mix. Positive reactions to nickel sulfate were more common among women, especially those in the younger age group (younger than 40 years). Positive reactions to balsam of Peru were more common among men, especially those in the older age group (40 years or older). This study presents the result of the standard patch test in Israel with stratification according to age and sex. The findings of the present study, combined with reports on geographic/population differences in the prevalence of specific allergens in CD, indicate the need for further investigations to identify prominent local allergens for better adaptation of the standard patch test to local needs.","Standard patch test results in patients with contact dermatitis in Israel: age and sex differences Abs: Previous studies have shown that the prevalence of specific allergens varies by geographic area, population, age and sex. The objective of the present study was to determine the relative frequency of positive reactions to different sensitizers in Israeli patients with clinically suspected contact dermatitis (CD) and to identify possible sex and age differences. A total of 943 consecutive patients were tested for CD using the European standard patch test series. The most frequent allergen was nickel sulfate followed by potassium dichromate and fragrance mix. Positive reactions to nickel sulfate were more common among women, especially those in the younger age group (younger than 40 years). Positive reactions to balsam of Peru were more common among men, especially those in the older age group (40 years or older). This study presents the result of the standard patch test in Israel with stratification according to age and sex. The findings of the present study, combined with reports on geographic/population differences in the prevalence of specific allergens in CD, indicate the need for further investigations to identify prominent local allergens for better adaptation of the standard patch test to local needs."
1234258,Lazarov et al. 2007,Comparison of reactivity to allergens using the TRUE Test and IQ chamber system,"The reproducibility of the patch test is of great importance to its diagnostic utility. The objective of this study was to quantitatively and qualitatively compare the reproducibility of patch test reactions between the manufacturer-loaded TRUE Test (TT) panel and the investigator-loaded IQ Chamber (IQC) system using the European Standard Series (ESS) (Chemotechnique Diagnostics, Malmö, Sweden). Consecutive patients were simultaneously patch tested with 21 allergens using the TT and IQC system. The concordance and discordance of the 2 methods were analysed. Testing was performed in 207 patients (85 men and 122 women) who yielded 317 positive reactions, 188 with the IQ system and 129 with the TT. A total of 204 tests were positive with both methods, showing a positive concordance rate of 64.4%, with IQC producing more positive results. A high concordance rate of positive results was achieved for Cl+ Me- isothiazolinone (81.5%), nickel sulfate (79%), formaldehyde (76.9%), and paraphenylenediamine (PPD) (72.7%); a moderate concordance was noted for quaternium 15 (66.7%), potassium dichromate (64.3%), and fragrance mix (58.1%); and a low concordance was noted for cobalt chloride (27.6%) and Balsam of Peru (18.2%). The IQC and the TT are similar in finding allergy to allergens with high concordance. The IQC system has an advantage in detecting clinically relevant reactions to allergens that have a moderate and a low concordance.","Comparison of reactivity to allergens using the TRUE Test and IQ chamber system Abs: The reproducibility of the patch test is of great importance to its diagnostic utility. The objective of this study was to quantitatively and qualitatively compare the reproducibility of patch test reactions between the manufacturer-loaded TRUE Test (TT) panel and the investigator-loaded IQ Chamber (IQC) system using the European Standard Series (ESS) (Chemotechnique Diagnostics, Malmö, Sweden). Consecutive patients were simultaneously patch tested with 21 allergens using the TT and IQC system. The concordance and discordance of the 2 methods were analysed. Testing was performed in 207 patients (85 men and 122 women) who yielded 317 positive reactions, 188 with the IQ system and 129 with the TT. A total of 204 tests were positive with both methods, showing a positive concordance rate of 64.4%, with IQC producing more positive results. A high concordance rate of positive results was achieved for Cl+ Me- isothiazolinone (81.5%), nickel sulfate (79%), formaldehyde (76.9%), and paraphenylenediamine (PPD) (72.7%); a moderate concordance was noted for quaternium 15 (66.7%), potassium dichromate (64.3%), and fragrance mix (58.1%); and a low concordance was noted for cobalt chloride (27.6%) and Balsam of Peru (18.2%). The IQC and the TT are similar in finding allergy to allergens with high concordance. The IQC system has an advantage in detecting clinically relevant reactions to allergens that have a moderate and a low concordance."
1234257,Colquhoun 2007,Treating critically ill patients with sugar pills,,Treating critically ill patients with sugar pills Abs: 
1234256,Reynolds and  Zhitkovich 2007,Cellular vitamin C increases chromate toxicity via a death program requiring mismatch repair but not p53,"Ascorbate (Asc) plays a key role in reductive activation of carcinogenic chromium(VI) in vivo. In addition to much higher rates (t(1/2) = 1 min for 1 mM Asc), its reactions at physiological conditions differ from other reducers by low yields of Cr(V) intermediates. Human cells in culture are severely Asc deficient, which results in distorted metabolism and potentially abnormal responses to Cr(VI). We found that restoration of physiological Asc levels in human lung cells (primary IMR90 fibroblasts and epithelial H460 cells) increased clonogenic lethality and apoptosis by Cr(VI). Enhanced cytotoxicity in mass cultures was more evident after normalization for lower Cr uptake caused by leakage of Asc into media. Asc did not change uptake-adjusted yields of Cr-DNA adducts and had no effect on cytotoxicity when delivered shortly after Cr(VI) exposure. Protein and Ser-15 phosphorylation levels of p53 did not show any association with the presence of Asc and there were no increases in p53-driven reporter activity in Cr-treated cells. Stable silencing of p53 expression by short hairpin RNA (shRNA) had no effect on toxicity of Cr(VI) in both -Asc and +Asc IMR90 and H460 cells. In contrast, shRNA-mediated depletion of essential components of MutS or MutL mismatch repair complexes greatly improved survival of all Cr-treated cells and eliminated Asc-potentiated effects on cell death. Thus, mismatch repair-mediated enhancement of Cr(VI) cytotoxicity by Asc should promote the selection of MSI+/wt-p53 phenotype found among chromate-induced human lung cancers. Our findings also indicate that Asc plays a dual role in Cr(VI) toxicity: protective outside and potentiating inside the cell.","Cellular vitamin C increases chromate toxicity via a death program requiring mismatch repair but not p53 Abs: Ascorbate (Asc) plays a key role in reductive activation of carcinogenic chromium(VI) in vivo. In addition to much higher rates (t(1/2) = 1 min for 1 mM Asc), its reactions at physiological conditions differ from other reducers by low yields of Cr(V) intermediates. Human cells in culture are severely Asc deficient, which results in distorted metabolism and potentially abnormal responses to Cr(VI). We found that restoration of physiological Asc levels in human lung cells (primary IMR90 fibroblasts and epithelial H460 cells) increased clonogenic lethality and apoptosis by Cr(VI). Enhanced cytotoxicity in mass cultures was more evident after normalization for lower Cr uptake caused by leakage of Asc into media. Asc did not change uptake-adjusted yields of Cr-DNA adducts and had no effect on cytotoxicity when delivered shortly after Cr(VI) exposure. Protein and Ser-15 phosphorylation levels of p53 did not show any association with the presence of Asc and there were no increases in p53-driven reporter activity in Cr-treated cells. Stable silencing of p53 expression by short hairpin RNA (shRNA) had no effect on toxicity of Cr(VI) in both -Asc and +Asc IMR90 and H460 cells. In contrast, shRNA-mediated depletion of essential components of MutS or MutL mismatch repair complexes greatly improved survival of all Cr-treated cells and eliminated Asc-potentiated effects on cell death. Thus, mismatch repair-mediated enhancement of Cr(VI) cytotoxicity by Asc should promote the selection of MSI+/wt-p53 phenotype found among chromate-induced human lung cancers. Our findings also indicate that Asc plays a dual role in Cr(VI) toxicity: protective outside and potentiating inside the cell."
1234253,Macedo et al. 2007,"Contact allergy in male construction workers in Sao Paulo, Brazil, 2000-2005","There are no recent data on allergens in the construction industry in Brazil; apparently there were no changes in allergenic substances. The objective of this study was to identify sensitization to allergens in adult males working in the construction industry. A cross-sectional study with adult males submitted to patch tests from May 2000 to December 2005. Out of 169 male patients, 83 were construction workers. The five most frequent allergens among the construction workers were potassium dichromate (57%), carba-mix (34.9%), cobalt chloride (30.2%), thiuram-mix (27.9%) and neomycin (19.8%). There is a significant sensitization to potassium dichromate, cobalt, carba-mix, and thiuram-mix, demonstrating that cement and rubber gloves of personal protection equipment still account for allergic contact dermatitis in construction industry workers.","Contact allergy in male construction workers in Sao Paulo, Brazil, 2000-2005 Abs: There are no recent data on allergens in the construction industry in Brazil; apparently there were no changes in allergenic substances. The objective of this study was to identify sensitization to allergens in adult males working in the construction industry. A cross-sectional study with adult males submitted to patch tests from May 2000 to December 2005. Out of 169 male patients, 83 were construction workers. The five most frequent allergens among the construction workers were potassium dichromate (57%), carba-mix (34.9%), cobalt chloride (30.2%), thiuram-mix (27.9%) and neomycin (19.8%). There is a significant sensitization to potassium dichromate, cobalt, carba-mix, and thiuram-mix, demonstrating that cement and rubber gloves of personal protection equipment still account for allergic contact dermatitis in construction industry workers."
1234252,Cristofori et al. 2007,Renal proximal tubule segment-specific nephrotoxicity: an overview on biomarkers and histopathology,"The correspondence between histopathological findings and segment-specific biomarkers was investigated in rats treated with segment-specific nephrotoxicants. Male Wistar rats were treated with a single injection of K2Cr2O7 (25 mg/kg s.c. in saline), cis-Pt (10 mg/kg i.p. in buffered MSO) or HCBD (100 mg/kg i.p. in corn oil). Twenty-four and 48 hours after treatment, the rats were sacrificed and the kidneys were drawn for histopathological and biochemical evaluation, i.e., GS activity in renal cortex and PAH uptake in renal cortical slices. Histopathological findings show that cis-Pt and HCBD cause diffuse necrosis of S3 segment of proximal tubules in the outer stripe of outer medulla, respectively. On the contrary, K2Cr2O7 damages exclusively S1-S2 segments, inducing vacuolization at 24 hr and diffuse necrosis at 48 hr after treatment. GS activity in renal tissue is significantly decreased after HCBD and cis-Pt, but not K2Cr2O7 treatment. In contrast, PAH uptake is significantly reduced by K2Cr2O7, but not by cis-Pt or HCBD treatment (even if HCBD causes a slight decrease 48 hr after treatment). The evidence of this study confirms the high specificity of GS activity as marker of S3 segment injury, that PAH uptake is prevalently active in the S1-S2 segments, and that there is complete correspondence among segment-specific nephrotoxicants, biomarkers of segment-specific damage, and histopathological findings.","Renal proximal tubule segment-specific nephrotoxicity: an overview on biomarkers and histopathology Abs: The correspondence between histopathological findings and segment-specific biomarkers was investigated in rats treated with segment-specific nephrotoxicants. Male Wistar rats were treated with a single injection of K2Cr2O7 (25 mg/kg s.c. in saline), cis-Pt (10 mg/kg i.p. in buffered MSO) or HCBD (100 mg/kg i.p. in corn oil). Twenty-four and 48 hours after treatment, the rats were sacrificed and the kidneys were drawn for histopathological and biochemical evaluation, i.e., GS activity in renal cortex and PAH uptake in renal cortical slices. Histopathological findings show that cis-Pt and HCBD cause diffuse necrosis of S3 segment of proximal tubules in the outer stripe of outer medulla, respectively. On the contrary, K2Cr2O7 damages exclusively S1-S2 segments, inducing vacuolization at 24 hr and diffuse necrosis at 48 hr after treatment. GS activity in renal tissue is significantly decreased after HCBD and cis-Pt, but not K2Cr2O7 treatment. In contrast, PAH uptake is significantly reduced by K2Cr2O7, but not by cis-Pt or HCBD treatment (even if HCBD causes a slight decrease 48 hr after treatment). The evidence of this study confirms the high specificity of GS activity as marker of S3 segment injury, that PAH uptake is prevalently active in the S1-S2 segments, and that there is complete correspondence among segment-specific nephrotoxicants, biomarkers of segment-specific damage, and histopathological findings."
1234251,Kimura 2007,Contact hypersensitivity to stainless steel cages (chromium metal) in hairless descendants of mexican hairless dogs,"Canine allergic contact hypersensitivity is an uncommon skin disease as compared with human beings because hair coat is a good natural barrier to environmental contactants. In our colony of hairless dogs housed in stainless steel cages, we have encountered spontaneously occurring contact hypersensitivity. The author has attempted to study the toxicological effects of environmental sensitizing substances on the canine skin. The purpose of this study is to elucidate dermatological characteristics in canine species with contact hypersensitivity. This skin lesion was investigated by patch tests, macroscopic observations, and histopathological examinations. Patch tests exhibited positive reactions to potassium dichromate. Macroscopically, early lesions were macules and/or papules and they gradually progressed to severe inflammatory dermatitis over the dorsum. In the chronic phase, lichenification, kyperkeratosis, hyperpigmentation, dryness, scaliness, and fissuring were observed in the skin. Avoidance of contact with the stainless steel cages resulted in clinical improvement. Histopathologically, the epidermis apparently showed hyperkeratosis, thickening, hyperplasia, and rete ridge formation. Lichenified lesions had clumps of melanin granules in the stratum basale and spinosum. In the dermis, there was marked edema and dense mononuclear cell infiltration. Vasodilation, hemorrhage, and hyperplasia of sebaceous glands were also found. Both dermal mast cells and epidermal Langerhans cells significantly increased in the skin lesions, as compared with nonlesional sites. The present results revealed that constant contact with stainless steel cages (chromium metal) caused contact hypersensitivity in hairless dogs with very sparse hairs.","Contact hypersensitivity to stainless steel cages (chromium metal) in hairless descendants of mexican hairless dogs Abs: Canine allergic contact hypersensitivity is an uncommon skin disease as compared with human beings because hair coat is a good natural barrier to environmental contactants. In our colony of hairless dogs housed in stainless steel cages, we have encountered spontaneously occurring contact hypersensitivity. The author has attempted to study the toxicological effects of environmental sensitizing substances on the canine skin. The purpose of this study is to elucidate dermatological characteristics in canine species with contact hypersensitivity. This skin lesion was investigated by patch tests, macroscopic observations, and histopathological examinations. Patch tests exhibited positive reactions to potassium dichromate. Macroscopically, early lesions were macules and/or papules and they gradually progressed to severe inflammatory dermatitis over the dorsum. In the chronic phase, lichenification, kyperkeratosis, hyperpigmentation, dryness, scaliness, and fissuring were observed in the skin. Avoidance of contact with the stainless steel cages resulted in clinical improvement. Histopathologically, the epidermis apparently showed hyperkeratosis, thickening, hyperplasia, and rete ridge formation. Lichenified lesions had clumps of melanin granules in the stratum basale and spinosum. In the dermis, there was marked edema and dense mononuclear cell infiltration. Vasodilation, hemorrhage, and hyperplasia of sebaceous glands were also found. Both dermal mast cells and epidermal Langerhans cells significantly increased in the skin lesions, as compared with nonlesional sites. The present results revealed that constant contact with stainless steel cages (chromium metal) caused contact hypersensitivity in hairless dogs with very sparse hairs."
1234250,Rodríguez et al. 2007,Validation of a capillary electrophoresis method for the analysis of ibandronate related impurities,"A capillary zone electrophoretic (CZE) method has been developed for the determination of impurities (phosphyte and phosphate) in technical-grade ibandronate, which is a potent nitrogen-containing bisphosphonate. Successful separation of the drug from the impurities was achieved using 1mM tetradecyl-trimethyl-ammonium bromide (TTAB) and 5mM potassium chromate (pH 10.0) as background electrolyte with an indirect detection at 254 nm. The optimised method was validated for specificity, precision, linearity and accuracy. The limit of detection (LOD) was 2 microg/mL and the limit of quantification (LOQ) was 7 microg/mL for both phosphyte and phosphate. The developed CZE method used to determine phosphyte and phosphate as bisphosphonates impurities can be used to evaluate the quality of regular production samples of ibandronate.","Validation of a capillary electrophoresis method for the analysis of ibandronate related impurities Abs: A capillary zone electrophoretic (CZE) method has been developed for the determination of impurities (phosphyte and phosphate) in technical-grade ibandronate, which is a potent nitrogen-containing bisphosphonate. Successful separation of the drug from the impurities was achieved using 1mM tetradecyl-trimethyl-ammonium bromide (TTAB) and 5mM potassium chromate (pH 10.0) as background electrolyte with an indirect detection at 254 nm. The optimised method was validated for specificity, precision, linearity and accuracy. The limit of detection (LOD) was 2 microg/mL and the limit of quantification (LOQ) was 7 microg/mL for both phosphyte and phosphate. The developed CZE method used to determine phosphyte and phosphate as bisphosphonates impurities can be used to evaluate the quality of regular production samples of ibandronate."
1234249,Xiang et al. 2007,Sensitive and selective spectrofluorimetric determination of chromium(VI) in water by fluorescence enhancement,"A new fluorogenic method for the selective and sensitive determination of chromium(VI) in acidic water using rhodamine B hydrazide was developed. This method was based on the oxidation of non-fluorescent rhodamine B hydrazide by potassium dichromate in acidic aqueous conditions to give rhodamine B, which was highly fluorescent, as a product. With the optimum condition described, the fluorescence enhancement at 585 nm was linearly related to the concentration of chromium(VI) in the range of 5.0 x 10(-8) to 2.0 x 10(-6) mol L(-1) (2.60-104 ng mL(-1)) with a correlation coefficient of R(2)=0.9993 (n=18) and a detection limit of 5.5 x 10(-9) mol L(-1) (0.29 ng mL(-1)). The R.S.D. was 2.2% (n=5). The proposed method was also applied to the determination of chromium(VI) in drinking water, river water and synthetic samples.","Sensitive and selective spectrofluorimetric determination of chromium(VI) in water by fluorescence enhancement Abs: A new fluorogenic method for the selective and sensitive determination of chromium(VI) in acidic water using rhodamine B hydrazide was developed. This method was based on the oxidation of non-fluorescent rhodamine B hydrazide by potassium dichromate in acidic aqueous conditions to give rhodamine B, which was highly fluorescent, as a product. With the optimum condition described, the fluorescence enhancement at 585 nm was linearly related to the concentration of chromium(VI) in the range of 5.0 x 10(-8) to 2.0 x 10(-6) mol L(-1) (2.60-104 ng mL(-1)) with a correlation coefficient of R(2)=0.9993 (n=18) and a detection limit of 5.5 x 10(-9) mol L(-1) (0.29 ng mL(-1)). The R.S.D. was 2.2% (n=5). The proposed method was also applied to the determination of chromium(VI) in drinking water, river water and synthetic samples."
1234248,Parsons et al. 2007,X-ray absorption near edge structure and extended X-ray absorption fine structure analysis of standards and biological samples containing mixed oxidation states of chromium(III) and chromium(VI),"For the first time a method has been developed for the extended X-ray absorption fine structure (EXAFS) data analyses of biological samples containing multiple oxidation states of chromium. In this study, the first shell coordination and interatomic distances based on the data analysis of known standards of potassium chromate (Cr(VI)) and chromium nitrate hexahydrate (Cr(III)) were investigated. The standards examined were mixtures of the following molar ratios of Cr(VI):Cr(III), 0:1, 0.25:0.75, 0.5:0.5, 0.75:0.25, and 1:0. It was determined from the calibration data that the fitting error associated with linear combination X-ray absorption near edge structure (LC-XANES) fittings was approximately +/-10% of the total fitting. The peak height of the Cr(VI) pre-edge feature after normalization of the X-ray absorption (XAS) spectra was used to prepare a calibration curve. The EXAFS fittings of the standards were also investigated and fittings to lechuguilla biomass samples laden with different ratios of Cr(III) and Cr(VI) were performed as well. An excellent agreement between the XANES data and the data presented in the EXAFS spectra was observed. The EXFAS data also presented mean coordination numbers directly related to the ratios of the different chromium oxidation states in the sample. The chromium oxygen interactions had two different bond lengths at approximately 1.68 and 1.98 A for the Cr(VI) and Cr(III) in the sample, respectively.","X-ray absorption near edge structure and extended X-ray absorption fine structure analysis of standards and biological samples containing mixed oxidation states of chromium(III) and chromium(VI) Abs: For the first time a method has been developed for the extended X-ray absorption fine structure (EXAFS) data analyses of biological samples containing multiple oxidation states of chromium. In this study, the first shell coordination and interatomic distances based on the data analysis of known standards of potassium chromate (Cr(VI)) and chromium nitrate hexahydrate (Cr(III)) were investigated. The standards examined were mixtures of the following molar ratios of Cr(VI):Cr(III), 0:1, 0.25:0.75, 0.5:0.5, 0.75:0.25, and 1:0. It was determined from the calibration data that the fitting error associated with linear combination X-ray absorption near edge structure (LC-XANES) fittings was approximately +/-10% of the total fitting. The peak height of the Cr(VI) pre-edge feature after normalization of the X-ray absorption (XAS) spectra was used to prepare a calibration curve. The EXAFS fittings of the standards were also investigated and fittings to lechuguilla biomass samples laden with different ratios of Cr(III) and Cr(VI) were performed as well. An excellent agreement between the XANES data and the data presented in the EXAFS spectra was observed. The EXFAS data also presented mean coordination numbers directly related to the ratios of the different chromium oxidation states in the sample. The chromium oxygen interactions had two different bond lengths at approximately 1.68 and 1.98 A for the Cr(VI) and Cr(III) in the sample, respectively."
1234247,Uddin et al. 2007,Dietary chromium and nickel enhance UV-carcinogenesis in skin of hairless mice,"The skin cancer enhancing effect of chromium (in male mice) and nickel in UVR-irradiated female Skh1 mice was investigated. The dietary vitamin E and selenomethionine were tested for prevention of chromium-enhanced skin carcinogenesis. The mice were exposed to UVR (1.0 kJ/m(2) 3 x weekly) for 26 weeks either alone, or combined with 2.5 or 5.0 ppm potassium chromate, or with 20, 100 or 500 ppm nickel chloride in drinking water. Vitamin E or selenomethionine was added to the lab chow for 29 weeks beginning 3 weeks before the start of UVR exposure. Both chromium and nickel significantly increased the UVR-induced skin cancer yield in mice. In male Skh1 mice, UVR alone induced 1.9+/-0.4 cancers/mouse, and 2.5 or 5.0 ppm potassium chromate added to drinking water increased the yields to 5.9+/-0.8 and 8.6+/-0.9 cancers/mouse, respectively. In female Skh1 mice, UVR alone induced 1.7+/-0.4 cancers/mouse, and the addition of 20, 100 or 500 ppm nickel chloride increased the yields to 2.8+/-0.9, 5.6+/-0.7 and 4.2+/-1.0 cancers/mouse, respectively. Neither vitamin E nor selenomethionine reduced the cancer yield enhancement by chromium. These results confirm that chromium and nickel, while not good skin carcinogens per se, are enhancers of UVR-induced skin cancers in Skh1 mice. Data also suggest that the enhancement of UVR-induced skin cancers by chromate may not be oxidatively mediated since the antioxidant vitamin E as well as selenomethionine, found to prevent arsenite-enhanced skin carcinogenesis, failed to suppress enhancement by chromate.","Dietary chromium and nickel enhance UV-carcinogenesis in skin of hairless mice Abs: The skin cancer enhancing effect of chromium (in male mice) and nickel in UVR-irradiated female Skh1 mice was investigated. The dietary vitamin E and selenomethionine were tested for prevention of chromium-enhanced skin carcinogenesis. The mice were exposed to UVR (1.0 kJ/m(2) 3 x weekly) for 26 weeks either alone, or combined with 2.5 or 5.0 ppm potassium chromate, or with 20, 100 or 500 ppm nickel chloride in drinking water. Vitamin E or selenomethionine was added to the lab chow for 29 weeks beginning 3 weeks before the start of UVR exposure. Both chromium and nickel significantly increased the UVR-induced skin cancer yield in mice. In male Skh1 mice, UVR alone induced 1.9+/-0.4 cancers/mouse, and 2.5 or 5.0 ppm potassium chromate added to drinking water increased the yields to 5.9+/-0.8 and 8.6+/-0.9 cancers/mouse, respectively. In female Skh1 mice, UVR alone induced 1.7+/-0.4 cancers/mouse, and the addition of 20, 100 or 500 ppm nickel chloride increased the yields to 2.8+/-0.9, 5.6+/-0.7 and 4.2+/-1.0 cancers/mouse, respectively. Neither vitamin E nor selenomethionine reduced the cancer yield enhancement by chromium. These results confirm that chromium and nickel, while not good skin carcinogens per se, are enhancers of UVR-induced skin cancers in Skh1 mice. Data also suggest that the enhancement of UVR-induced skin cancers by chromate may not be oxidatively mediated since the antioxidant vitamin E as well as selenomethionine, found to prevent arsenite-enhanced skin carcinogenesis, failed to suppress enhancement by chromate."
1234246,Medina-Campos et al. 2007,S-allylcysteine scavenges singlet oxygen and hypochlorous acid and protects LLC-PK(1) cells of potassium dichromate-induced toxicity,"It has been found that S-allylcysteine (SAC), a garlic-derived compound, has in vivo and in vitro antioxidant properties. In addition, it is known that SAC is able to scavenge different reactive oxygen or nitrogen species including superoxide anion (O(2)(-)), hydrogen peroxide (H(2)O(2)), hydroxyl radical (OH()), and peroxynitrite anion (ONOO(-)) although the IC(5O) values for each reactive species has not been calculated and the potential ability of SAC to scavenge singlet oxygen ((1)O(2)) and hypochlorous acid (HOCl) has not been explored. The purposes of this work was (a) to explore the potential ability of SAC to scavenge (1)O(2) and HOCl, (b) to further characterize the O(2)(-), H(2)O(2), OH(), and ONOO(-) scavenging ability of SAC by measuring the IC(50) values using in vitro assays, and (c) to explore the potential ability of SAC to ameliorate the potassium dichromate (K(2)Cr(2)O(7))-induced cytotoxicity in LLC-PK1 cells in which oxidative stress is involved. The scavenging activity was compared against the following reference compounds: N-acetylcysteine for O(2)(-), sodium pyruvate for H(2)O(2), dimethylthiourea for OH(), lipoic acid and glutathione for (1)O(2), lipoic acid for HOCl, and penicillamine for ONOO(-). It was found that SAC was able to scavenge concentration-dependently all the species assayed with the following IC(5O) (mean+/-SEM, mM): O(2)(-) (14.49+/-1.67), H(2)O(2) (68+/-1.92), OH() (0.68+/-0.06), (1)O(2) (1.93+/-0.27), HOCl (2.86+/-0.15), and ONOO(-) (0.80+/-0.05). When the ability of SAC to scavenge these species was compared to those of the reference compounds it was found that the efficacy of SAC (a) to scavenge O(2)(-), H(2)O(2), OH(), and ONOO(-) was lower, (b) to scavenge HOCl was similar, and (c) to scavenge (1)O(2) was higher. In addition, it was found that SAC was able to prevent K(2)Cr(2)O(7)-induced toxicity in LLC-PK1 cells in culture. It was showed for the first time that SAC is able to scavenge (1)O(2) and HOCl and to ameliorate the K(2)Cr(2)O(7)-induced toxicity.","S-allylcysteine scavenges singlet oxygen and hypochlorous acid and protects LLC-PK(1) cells of potassium dichromate-induced toxicity Abs: It has been found that S-allylcysteine (SAC), a garlic-derived compound, has in vivo and in vitro antioxidant properties. In addition, it is known that SAC is able to scavenge different reactive oxygen or nitrogen species including superoxide anion (O(2)(-)), hydrogen peroxide (H(2)O(2)), hydroxyl radical (OH()), and peroxynitrite anion (ONOO(-)) although the IC(5O) values for each reactive species has not been calculated and the potential ability of SAC to scavenge singlet oxygen ((1)O(2)) and hypochlorous acid (HOCl) has not been explored. The purposes of this work was (a) to explore the potential ability of SAC to scavenge (1)O(2) and HOCl, (b) to further characterize the O(2)(-), H(2)O(2), OH(), and ONOO(-) scavenging ability of SAC by measuring the IC(50) values using in vitro assays, and (c) to explore the potential ability of SAC to ameliorate the potassium dichromate (K(2)Cr(2)O(7))-induced cytotoxicity in LLC-PK1 cells in which oxidative stress is involved. The scavenging activity was compared against the following reference compounds: N-acetylcysteine for O(2)(-), sodium pyruvate for H(2)O(2), dimethylthiourea for OH(), lipoic acid and glutathione for (1)O(2), lipoic acid for HOCl, and penicillamine for ONOO(-). It was found that SAC was able to scavenge concentration-dependently all the species assayed with the following IC(5O) (mean+/-SEM, mM): O(2)(-) (14.49+/-1.67), H(2)O(2) (68+/-1.92), OH() (0.68+/-0.06), (1)O(2) (1.93+/-0.27), HOCl (2.86+/-0.15), and ONOO(-) (0.80+/-0.05). When the ability of SAC to scavenge these species was compared to those of the reference compounds it was found that the efficacy of SAC (a) to scavenge O(2)(-), H(2)O(2), OH(), and ONOO(-) was lower, (b) to scavenge HOCl was similar, and (c) to scavenge (1)O(2) was higher. In addition, it was found that SAC was able to prevent K(2)Cr(2)O(7)-induced toxicity in LLC-PK1 cells in culture. It was showed for the first time that SAC is able to scavenge (1)O(2) and HOCl and to ameliorate the K(2)Cr(2)O(7)-induced toxicity."
1234243,Narendra and  Srinivas 2002,Patch testing with Indian standard series,"Hundred patients (61 males, 39 females) suspected to have allergic contact dermatitis were patch tested with Indian standard series (ISS). Forty four showed one or more positive reactions. The frequent sensitizers observed were nickel sulphate--12 (15%), potassium dichromate--11 (13.75%), cobalt chloride and colophony--7 (8.75%) each, fragrance mix and thiuram mix--6 (7.5%) each. The ISS differs from the European Standard Series by inclusion of propylene glycol, nitrofurazone, gentamicin, chlorocresol, PEG-400 and ethylenediamine chloride where assesquiterpene lactone mix and primin allergens are excluded.","Patch testing with Indian standard series Abs: Hundred patients (61 males, 39 females) suspected to have allergic contact dermatitis were patch tested with Indian standard series (ISS). Forty four showed one or more positive reactions. The frequent sensitizers observed were nickel sulphate--12 (15%), potassium dichromate--11 (13.75%), cobalt chloride and colophony--7 (8.75%) each, fragrance mix and thiuram mix--6 (7.5%) each. The ISS differs from the European Standard Series by inclusion of propylene glycol, nitrofurazone, gentamicin, chlorocresol, PEG-400 and ethylenediamine chloride where assesquiterpene lactone mix and primin allergens are excluded."
1234242,Gorbi et al. 2007,Sulfur starvation and chromium tolerance in Scenedesmus acutus: a possible link between metal tolerance and the regulation of sulfur uptake/assimilation processes,"In a laboratory-selected Cr-tolerant strain of the unicellular green alga Scenedesmus acutus, the capacity to synthesize higher amounts of cysteine (Cys) and reduced glutathione (GSH) than the wild-type was demonstrated to underlie tolerance to Cd and Cr(VI). In photosynthetic organisms sulfate constitutes the main sulfur source for the biosynthesis of GSH and its precursor Cys, hence it was hypothesized that the sensitivity of the two strains to Cr(VI) could be modified after culturing in sulfate-deprived medium. Both strains were grown in the presence of different concentrations or in the absence of sulfate (sulfur-starved) and then assayed for Cr(VI) tolerance in standard medium. Unstarved, sulfur-starved and sulfur-replete cells (cells maintained in standard medium after S-starvation) were analysed for Cys, GSH and sulfur content. Sulfur-starved cells showed a greater tolerance to Cr(VI) than unstarved ones. The increased tolerance was ascribable to a transient physiological change and can be considered as specifically due to sulfur deprivation, since it was lost after a 3-day culture in standard medium and was not exhibited by nitrogen-starved cells. The comparison between Cys, GSH and sulfur content in sulfur-starved and sulfur-replete cells of the two strains suggests that the higher tolerance to Cr(VI) after S-starvation could depend on the up-regulation of sulfate uptake mechanisms, and that the primary reason for the higher tolerance to chromium in the selected strain could be due to greater sensitivity to the decrease in negative intracellular end-products (free Cys and GSH) leading to an earlier up-regulation of sulfate assimilation processes.","Sulfur starvation and chromium tolerance in Scenedesmus acutus: a possible link between metal tolerance and the regulation of sulfur uptake/assimilation processes Abs: In a laboratory-selected Cr-tolerant strain of the unicellular green alga Scenedesmus acutus, the capacity to synthesize higher amounts of cysteine (Cys) and reduced glutathione (GSH) than the wild-type was demonstrated to underlie tolerance to Cd and Cr(VI). In photosynthetic organisms sulfate constitutes the main sulfur source for the biosynthesis of GSH and its precursor Cys, hence it was hypothesized that the sensitivity of the two strains to Cr(VI) could be modified after culturing in sulfate-deprived medium. Both strains were grown in the presence of different concentrations or in the absence of sulfate (sulfur-starved) and then assayed for Cr(VI) tolerance in standard medium. Unstarved, sulfur-starved and sulfur-replete cells (cells maintained in standard medium after S-starvation) were analysed for Cys, GSH and sulfur content. Sulfur-starved cells showed a greater tolerance to Cr(VI) than unstarved ones. The increased tolerance was ascribable to a transient physiological change and can be considered as specifically due to sulfur deprivation, since it was lost after a 3-day culture in standard medium and was not exhibited by nitrogen-starved cells. The comparison between Cys, GSH and sulfur content in sulfur-starved and sulfur-replete cells of the two strains suggests that the higher tolerance to Cr(VI) after S-starvation could depend on the up-regulation of sulfate uptake mechanisms, and that the primary reason for the higher tolerance to chromium in the selected strain could be due to greater sensitivity to the decrease in negative intracellular end-products (free Cys and GSH) leading to an earlier up-regulation of sulfate assimilation processes."
1234241,Jemec et al. 2008,Biochemical biomarkers in chronically metal-stressed daphnids,"Biochemical biomarkers are a popular measure of toxic effects on organisms due to their assumed fast response, and are usually assessed after acute exposure of the organism to the stressor. However, increasing interest in the use of biochemical biomarkers in environmental pollution monitoring calls for more laboratory long-term studies of contaminants' effects on biochemical endpoints. In this study, four biochemical biomarkers (protein content, activity of cholinesterase (ChE), catalase (CAT) and glutathione S-transferase (GST), were correlated with standardised reproductive and survival endpoints of water fleas (Daphnia magna) after chronic exposure to Cr (VI) and Cd. No effect on the reproduction and survival was noticed up to the highest tested concentration of Cr (VI) (52.5 microg/L), while the protein content, and the ChE and CAT activity decreased, and GST activity increased. Cd affected reproduction of daphnids above 0.656 microg/L, but the protein content and ChE activity were changed at 0.328 microg/L and 0.082 microg/L of Cd, respectively. Biochemical biomarkers in some cases proved to be equally or more sensitive than reproduction and mortality. We recommend more frequent use of a battery of biochemical biomarkers in combination with other higher-level biomarkers also in chronic studies and not only in the acute ones.","Biochemical biomarkers in chronically metal-stressed daphnids Abs: Biochemical biomarkers are a popular measure of toxic effects on organisms due to their assumed fast response, and are usually assessed after acute exposure of the organism to the stressor. However, increasing interest in the use of biochemical biomarkers in environmental pollution monitoring calls for more laboratory long-term studies of contaminants' effects on biochemical endpoints. In this study, four biochemical biomarkers (protein content, activity of cholinesterase (ChE), catalase (CAT) and glutathione S-transferase (GST), were correlated with standardised reproductive and survival endpoints of water fleas (Daphnia magna) after chronic exposure to Cr (VI) and Cd. No effect on the reproduction and survival was noticed up to the highest tested concentration of Cr (VI) (52.5 microg/L), while the protein content, and the ChE and CAT activity decreased, and GST activity increased. Cd affected reproduction of daphnids above 0.656 microg/L, but the protein content and ChE activity were changed at 0.328 microg/L and 0.082 microg/L of Cd, respectively. Biochemical biomarkers in some cases proved to be equally or more sensitive than reproduction and mortality. We recommend more frequent use of a battery of biochemical biomarkers in combination with other higher-level biomarkers also in chronic studies and not only in the acute ones."
1234240,Chandra et al. 2007,Chromium induced testicular impairment in relation to adrenocortical activities in adult albino rats,"The present study investigates the testicular and adrenocortical activities under different doses and durations of chromium (Cr) exposure and their interactions. Mature male Sprague Dawley rats were injected daily with three different doses (0.2, 0.4, and 0.6 mg/kg bw) of Cr salt (K(2)Cr(2)O(7)) intraperitonealy for 13 and 26 days, respectively. The medium (0.4 mg/kg bw/day) and higher dose (0.6 mg/kg bw/day) of Cr significantly (p&lt;0.05) decrease accessory sex organs weight, testicular Delta(5)3beta-hydroxysteroid dehydrogenase (HSD) and 17beta-HSD activities, epididymal sperm count, effective spermatid degeneration, serum testosterone, LH level, testicular catalase and superoxide dismutase (SOD) activities while testicular lipid peroxidation, serum FSH, corticosterone level, adrenal weight and adrenal Delta(5)3beta-HSD activity increased significantly than that of control and lower dose (0.2 mg/kg bw/day) Cr exposed animals. Testicular histoarchitechture shows deterioration after critical dose (0.4 mg/kg bw/day) and duration (26 days) of Cr exposure. Cr induced alterations on testicular and adrenocortical activities are dose and duration dependent. Adrecortical hyperactivity accompanied by testicular oxidative stress might have a crucial role for Cr induced male reproductive impairment.","Chromium induced testicular impairment in relation to adrenocortical activities in adult albino rats Abs: The present study investigates the testicular and adrenocortical activities under different doses and durations of chromium (Cr) exposure and their interactions. Mature male Sprague Dawley rats were injected daily with three different doses (0.2, 0.4, and 0.6 mg/kg bw) of Cr salt (K(2)Cr(2)O(7)) intraperitonealy for 13 and 26 days, respectively. The medium (0.4 mg/kg bw/day) and higher dose (0.6 mg/kg bw/day) of Cr significantly (p&lt;0.05) decrease accessory sex organs weight, testicular Delta(5)3beta-hydroxysteroid dehydrogenase (HSD) and 17beta-HSD activities, epididymal sperm count, effective spermatid degeneration, serum testosterone, LH level, testicular catalase and superoxide dismutase (SOD) activities while testicular lipid peroxidation, serum FSH, corticosterone level, adrenal weight and adrenal Delta(5)3beta-HSD activity increased significantly than that of control and lower dose (0.2 mg/kg bw/day) Cr exposed animals. Testicular histoarchitechture shows deterioration after critical dose (0.4 mg/kg bw/day) and duration (26 days) of Cr exposure. Cr induced alterations on testicular and adrenocortical activities are dose and duration dependent. Adrecortical hyperactivity accompanied by testicular oxidative stress might have a crucial role for Cr induced male reproductive impairment."
1234239,Asakai et al. 2007,Precise coulometric titration of sodium thiosulfate and development of potassium iodate as a redox standard,"In this paper, we determine the effective purity of potassium iodate as a redox standard with a certified value linked to the international system of units (SI units). Concentration measurement of sodium thiosulfate solution was performed by precise coulometric titration with electrogenerated iodine, and an assay of potassium iodate was carried out by gravimetric titration based on the reductometric factor of sodium thiosulfate assigned by coulometry. The accuracy of the coulometric titration method was evaluated by examining the current efficiency of iodine electrogeneration, stability of sodium thiosulfate solutions and dependence on the amount of sodium thiosulfate solution used. The measurement procedure for gravimetric titration of potassium iodate with sodium thiosulfate was validated based on determination of a reference material of known purity (potassium dichromate determined by coulometry with electrogenerated ferrous ions) using the same gravimetric method. Solutions of 0.2 and 0.5mol/L sodium thiosulfate were stable over 17 days without stabilizer. Investigation of the dependency of titration results on the amount of sodium thiosulfate solution used showed no significant effects, no evidence of diffusion of the sample, and no effect of contamination appearing during the experiment. Precise coulometric titration of sodium thiosulfate achieved a relative standard deviation of less than 0.005% under repeating conditions (six measurements). For gravimetric titration, the results obtained for the effective purity of potassium dichromate were sufficiently close to its certified value to allow confirmation of the validity of the gravimetric titration was confirmed. The relative standard deviation of gravimetric titration for potassium iodate was less than 0.011% (nine measurements), and a redox standard with a certified value linked to SI units was developed.","Precise coulometric titration of sodium thiosulfate and development of potassium iodate as a redox standard Abs: In this paper, we determine the effective purity of potassium iodate as a redox standard with a certified value linked to the international system of units (SI units). Concentration measurement of sodium thiosulfate solution was performed by precise coulometric titration with electrogenerated iodine, and an assay of potassium iodate was carried out by gravimetric titration based on the reductometric factor of sodium thiosulfate assigned by coulometry. The accuracy of the coulometric titration method was evaluated by examining the current efficiency of iodine electrogeneration, stability of sodium thiosulfate solutions and dependence on the amount of sodium thiosulfate solution used. The measurement procedure for gravimetric titration of potassium iodate with sodium thiosulfate was validated based on determination of a reference material of known purity (potassium dichromate determined by coulometry with electrogenerated ferrous ions) using the same gravimetric method. Solutions of 0.2 and 0.5mol/L sodium thiosulfate were stable over 17 days without stabilizer. Investigation of the dependency of titration results on the amount of sodium thiosulfate solution used showed no significant effects, no evidence of diffusion of the sample, and no effect of contamination appearing during the experiment. Precise coulometric titration of sodium thiosulfate achieved a relative standard deviation of less than 0.005% under repeating conditions (six measurements). For gravimetric titration, the results obtained for the effective purity of potassium dichromate were sufficiently close to its certified value to allow confirmation of the validity of the gravimetric titration was confirmed. The relative standard deviation of gravimetric titration for potassium iodate was less than 0.011% (nine measurements), and a redox standard with a certified value linked to SI units was developed."
1234238,Anderson et al. 2007,Incomplete oxidation of ethylenediaminetetraacetic acid in chemical oxygen demand analysis,"Ethylenediaminetetraacetic acid (EDTA) was found to incompletely oxidize in chemical oxygen demand (COD) analysis, leading to incorrect COD values for water samples containing relatively large amounts of EDTA. The degree of oxidation depended on the oxidant used, its concentration, and the length of digestion. The COD concentrations measured using COD vials with a potassium dichromate concentration of 0.10 N (after dilution by sample and sulfuric acid) were near theoretical oxygen demand values. However, COD measured with dichromate concentrations of 0.010 N and 0.0022 N were 30 to 40% lower than theoretical oxygen demand values. Similarly, lower COD values were observed with manganic sulfate as oxidant at 0.011 N. Extended digestion yielded somewhat higher COD values, suggesting incomplete and slower oxidation of EDTA, as a result of lower oxidant concentrations. For wastewater in which EDTA is a large fraction of COD, accurate COD measurement may not be achieved with methods using dichromate concentrations less than 0.1 N.","Incomplete oxidation of ethylenediaminetetraacetic acid in chemical oxygen demand analysis Abs: Ethylenediaminetetraacetic acid (EDTA) was found to incompletely oxidize in chemical oxygen demand (COD) analysis, leading to incorrect COD values for water samples containing relatively large amounts of EDTA. The degree of oxidation depended on the oxidant used, its concentration, and the length of digestion. The COD concentrations measured using COD vials with a potassium dichromate concentration of 0.10 N (after dilution by sample and sulfuric acid) were near theoretical oxygen demand values. However, COD measured with dichromate concentrations of 0.010 N and 0.0022 N were 30 to 40% lower than theoretical oxygen demand values. Similarly, lower COD values were observed with manganic sulfate as oxidant at 0.011 N. Extended digestion yielded somewhat higher COD values, suggesting incomplete and slower oxidation of EDTA, as a result of lower oxidant concentrations. For wastewater in which EDTA is a large fraction of COD, accurate COD measurement may not be achieved with methods using dichromate concentrations less than 0.1 N."
1234236,Bajaj et al. 2007,Patch testing experience with 1000 patients,"<strong>BACKGROUND: </strong>Patch testing is a definitive tool for diagnosing allergic contact dermatitis (ACD). It reveals the prevalence and trends of contact sensitization in the community, thereby paving the way for better standard series. There is paucity of large series of patch-tested patients from India.<br /><br /><strong>AIM: </strong>To report the 9-year patch-test data from a single general dermatology centre in North India.<br /><br /><strong>METHODS: </strong>Consecutive patients presenting with signs/symptoms of suspected ACD were patch tested from May 1997 to April 2006. The Indian Standard Series was used. Parthenium was tested only in selected patients and cetrimide and chloroxylenol were added to the series.<br /><br /><strong>RESULTS: </strong>In total, records of 1000 patients (566 male, 434 female) were analyzed, yielding 1155 positive reactions in 590 (59%) patients. Footwear dermatitis was the commonest suspected diagnosis, followed by ACD to medicaments, cosmetic dermatitis and plant dermatitis. Out of the allergens that were tested in all the patients, positivity to nickel was the commonest (12.9%), followed by potassium dichromate (11.1%) neomycin (7%), mercaptobenzthiazole (6.6%), nitrofurazone (6%), colophony (5.7%), fragrance mix (5.5%) and cobalt chloride (5.4%). However, parthenium was the commonest allergen based on the proportion of patients tested with it (14.5%). In men, potassium dichromate (30%) was the commonest sensitizer and in women, nickel (43%) was the commonest to show patch-test positivity.<br /><br /><strong>CONCLUSION: </strong>Our study revealed higher prevalence of footwear and medicament dermatitis in comparison to existing data. Allergy to antiseptics is significant in our patients. Further collaborative studies involving patients from other parts of India are required to have an overall view of ACD in India.","Patch testing experience with 1000 patients Abs: <strong>BACKGROUND: </strong>Patch testing is a definitive tool for diagnosing allergic contact dermatitis (ACD). It reveals the prevalence and trends of contact sensitization in the community, thereby paving the way for better standard series. There is paucity of large series of patch-tested patients from India.<br /><br /><strong>AIM: </strong>To report the 9-year patch-test data from a single general dermatology centre in North India.<br /><br /><strong>METHODS: </strong>Consecutive patients presenting with signs/symptoms of suspected ACD were patch tested from May 1997 to April 2006. The Indian Standard Series was used. Parthenium was tested only in selected patients and cetrimide and chloroxylenol were added to the series.<br /><br /><strong>RESULTS: </strong>In total, records of 1000 patients (566 male, 434 female) were analyzed, yielding 1155 positive reactions in 590 (59%) patients. Footwear dermatitis was the commonest suspected diagnosis, followed by ACD to medicaments, cosmetic dermatitis and plant dermatitis. Out of the allergens that were tested in all the patients, positivity to nickel was the commonest (12.9%), followed by potassium dichromate (11.1%) neomycin (7%), mercaptobenzthiazole (6.6%), nitrofurazone (6%), colophony (5.7%), fragrance mix (5.5%) and cobalt chloride (5.4%). However, parthenium was the commonest allergen based on the proportion of patients tested with it (14.5%). In men, potassium dichromate (30%) was the commonest sensitizer and in women, nickel (43%) was the commonest to show patch-test positivity.<br /><br /><strong>CONCLUSION: </strong>Our study revealed higher prevalence of footwear and medicament dermatitis in comparison to existing data. Allergy to antiseptics is significant in our patients. Further collaborative studies involving patients from other parts of India are required to have an overall view of ACD in India."
1234235,Chowdhuri and  Ghosh 2007,Epidemio-allergological study in 155 cases of footwear dermatitis,"<strong>BACKGROUND: </strong>Footwear dermatitis represents a distinct and common group among all types of contact dermatitis cases seen in India. This ailment, however, often remains undiagnosed, misdiagnosed or empirically diagnosed without pinpointing the contributory allergens.<br /><br /><strong>AIMS: </strong>This study was undertaken to detect the epidemio-allergological pattern of footwear dermatitis in India.<br /><br /><strong>METHODS: </strong>A total number of 155 cases with footwear dermatitis were evaluated from July 2005 to June 2006, by detailed history and clinical examination. They were patch tested using Indian Standard Battery (ISB) approved by the Contact and Occupational Dermatoses Forum of India (CODFI) with pre- and post patch-test counseling.<br /><br /><strong>RESULTS: </strong>The proportion of footwear dermatitis was 24.22% (n=155) among a total of 640 patients patch tested during that period. Females [61.93% (n=96)] were commonly affected than males [38.06% (n=59)]. The ages ranged from 8 to 75 years. The age group that predominantly involved was the fifth decade [24.52% (n=38)]. Occupationwise housewives were most commonly involved [47.48 (n=66)]. Contributory allergens in order of frequency were: potassium dichromate, 45.8% (n=71); cobalt chloride, 38.06% (n=59); paraphenylenediamine, 32.25% (n=50); epoxy resin, 20% (n=31); black rubber mix, 20% (n=31); nickel sulfate, 14.83% (n=23); mercaptobenzothiazole, 12.9% (n=20); colophony, 11.6% (n=18); thiuram mix, 10.32 % (n=16); p-tert-butyl-formaldehyde resin, 9.67% (n=15); and formaldehyde, 4.5% (n=7). Among the different categories of footwear allergens, the highest positivity was shown by leather and leather-related chemicals in 61.9% cases (n=96).<br /><br /><strong>CONCLUSION: </strong>Footwear dermatitis, a common dermatosis, is mostly caused by leather processing chemicals, metal buckles, black dyes of shoes and socks, adhesives, plastic, rubber shoes and polishing agents in order of frequency.","Epidemio-allergological study in 155 cases of footwear dermatitis Abs: <strong>BACKGROUND: </strong>Footwear dermatitis represents a distinct and common group among all types of contact dermatitis cases seen in India. This ailment, however, often remains undiagnosed, misdiagnosed or empirically diagnosed without pinpointing the contributory allergens.<br /><br /><strong>AIMS: </strong>This study was undertaken to detect the epidemio-allergological pattern of footwear dermatitis in India.<br /><br /><strong>METHODS: </strong>A total number of 155 cases with footwear dermatitis were evaluated from July 2005 to June 2006, by detailed history and clinical examination. They were patch tested using Indian Standard Battery (ISB) approved by the Contact and Occupational Dermatoses Forum of India (CODFI) with pre- and post patch-test counseling.<br /><br /><strong>RESULTS: </strong>The proportion of footwear dermatitis was 24.22% (n=155) among a total of 640 patients patch tested during that period. Females [61.93% (n=96)] were commonly affected than males [38.06% (n=59)]. The ages ranged from 8 to 75 years. The age group that predominantly involved was the fifth decade [24.52% (n=38)]. Occupationwise housewives were most commonly involved [47.48 (n=66)]. Contributory allergens in order of frequency were: potassium dichromate, 45.8% (n=71); cobalt chloride, 38.06% (n=59); paraphenylenediamine, 32.25% (n=50); epoxy resin, 20% (n=31); black rubber mix, 20% (n=31); nickel sulfate, 14.83% (n=23); mercaptobenzothiazole, 12.9% (n=20); colophony, 11.6% (n=18); thiuram mix, 10.32 % (n=16); p-tert-butyl-formaldehyde resin, 9.67% (n=15); and formaldehyde, 4.5% (n=7). Among the different categories of footwear allergens, the highest positivity was shown by leather and leather-related chemicals in 61.9% cases (n=96).<br /><br /><strong>CONCLUSION: </strong>Footwear dermatitis, a common dermatosis, is mostly caused by leather processing chemicals, metal buckles, black dyes of shoes and socks, adhesives, plastic, rubber shoes and polishing agents in order of frequency."
1234234,Pedraza-Chaverri et al. 2008,Protective effects of garlic powder against potassium dichromate-induced oxidative stress and nephrotoxicity,"Potassium dichromate (K(2)Cr(2)O(7))-induced nephrotoxicity is associated with oxidative stress. In the present work the effect of garlic powder, a recognized antioxidant, on K(2)Cr(2)O(7)-induced nephrotoxicity and oxidative stress was studied. Rats were fed a 2% garlic powder diet for 1 month. A single injection of K(2)Cr(2)O(7) (15 mg/kg) to rats induced tubule interstitial damage and an increase in the following markers of renal injury 2 days later: blood urea nitrogen (4.6-fold), serum creatinine (9.7-fold), proteinuria (35.9-fold), urinary excretion of N-acetyl-beta-d-glucosaminidase (12.9-fold) and glutathione-S-transferase (2.3-fold) and a decrease of 65% in serum glutathione peroxidase activity. In addition, K(2)Cr(2)O(7) injection increased the following nitrosative and oxidative stress markers in kidney: 3-nitrotyrosine (1.9-fold), 4-hydroxy-2-nonenal (2.1-fold), malondialdehyde (1.8-fold) and protein carbonyl content (1.7-fold). It was found that garlic powder feeding was able to prevent by 44-71% the alterations in the markers of renal injury studied, by 55% the histological damage, and by 47-100% the increase in markers of oxidative and nitrosative stress. It is concluded that the ability of garlic powder to ameliorate K(2)Cr(2)O(7)-induced renal injury is associated with its antioxidant properties. Our data support the use of garlic powder as a renoprotective agent.","Protective effects of garlic powder against potassium dichromate-induced oxidative stress and nephrotoxicity Abs: Potassium dichromate (K(2)Cr(2)O(7))-induced nephrotoxicity is associated with oxidative stress. In the present work the effect of garlic powder, a recognized antioxidant, on K(2)Cr(2)O(7)-induced nephrotoxicity and oxidative stress was studied. Rats were fed a 2% garlic powder diet for 1 month. A single injection of K(2)Cr(2)O(7) (15 mg/kg) to rats induced tubule interstitial damage and an increase in the following markers of renal injury 2 days later: blood urea nitrogen (4.6-fold), serum creatinine (9.7-fold), proteinuria (35.9-fold), urinary excretion of N-acetyl-beta-d-glucosaminidase (12.9-fold) and glutathione-S-transferase (2.3-fold) and a decrease of 65% in serum glutathione peroxidase activity. In addition, K(2)Cr(2)O(7) injection increased the following nitrosative and oxidative stress markers in kidney: 3-nitrotyrosine (1.9-fold), 4-hydroxy-2-nonenal (2.1-fold), malondialdehyde (1.8-fold) and protein carbonyl content (1.7-fold). It was found that garlic powder feeding was able to prevent by 44-71% the alterations in the markers of renal injury studied, by 55% the histological damage, and by 47-100% the increase in markers of oxidative and nitrosative stress. It is concluded that the ability of garlic powder to ameliorate K(2)Cr(2)O(7)-induced renal injury is associated with its antioxidant properties. Our data support the use of garlic powder as a renoprotective agent."
1234233,Chen et al. 2007,Comparison of viability and infectivity of Cryptosporidium parvum oocysts stored in potassium dichromate solution and chlorinated tap water,"The present study was undertaken to compare the viability and infectivity of Cryptosporidium parvum oocysts that had been stored for 1, 4, 7, 10, 13, 16, 20, 25 and 30 months at 4 degrees C in 2.5% potassium dichromate (Cr) or chlorinated tap water, respectively. An excystation protocol was performed in vitro to evaluate viability. One hundred and eighty female BABL/c mice were used to evaluate the infectivity of oocysts by investigating the prepatent period of C. parvum infection, the quantity of oocysts excreted, and the number of parasites that colonized the villi of the ileum. The results showed that C. parvum oocysts preserved in Cr for 1-16 months or in water for 1-13 months were capable of excystation in vitro and infection of mice. The excystation rates of oocysts and the prepatent periods in mice infected by oocysts stored in Cr and water were not significantly different (p&gt;0.05), and there was a strong correlation between prepatent period and duration of oocyst storage (Cr: R2=0.92; water: R2=0.98). There were no significant differences in oocyst shedding from feces or parasitism of the terminal ilea of mice by Cryptosporidia between the two storage media (p&gt;0.05). In conclusion, C. parvum oocysts may be stored at 4 degrees C in water instead of Cr for the purposes of laboratory research. However, the presence of viable C. parvum oocysts in water is a severe challenge to the drinking water treatment industry.","Comparison of viability and infectivity of Cryptosporidium parvum oocysts stored in potassium dichromate solution and chlorinated tap water Abs: The present study was undertaken to compare the viability and infectivity of Cryptosporidium parvum oocysts that had been stored for 1, 4, 7, 10, 13, 16, 20, 25 and 30 months at 4 degrees C in 2.5% potassium dichromate (Cr) or chlorinated tap water, respectively. An excystation protocol was performed in vitro to evaluate viability. One hundred and eighty female BABL/c mice were used to evaluate the infectivity of oocysts by investigating the prepatent period of C. parvum infection, the quantity of oocysts excreted, and the number of parasites that colonized the villi of the ileum. The results showed that C. parvum oocysts preserved in Cr for 1-16 months or in water for 1-13 months were capable of excystation in vitro and infection of mice. The excystation rates of oocysts and the prepatent periods in mice infected by oocysts stored in Cr and water were not significantly different (p&gt;0.05), and there was a strong correlation between prepatent period and duration of oocyst storage (Cr: R2=0.92; water: R2=0.98). There were no significant differences in oocyst shedding from feces or parasitism of the terminal ilea of mice by Cryptosporidia between the two storage media (p&gt;0.05). In conclusion, C. parvum oocysts may be stored at 4 degrees C in water instead of Cr for the purposes of laboratory research. However, the presence of viable C. parvum oocysts in water is a severe challenge to the drinking water treatment industry."
1234232,Paixão et al. 2008,Performance of a miniaturized algal bioassay in phytotoxicity screening,"A miniaturized and low-cost algal growth-inhibition assay, with Pseudokirchneriella subcapitata, based on the standard ISO 8692 and using 96-well microplates, was tested and optimized in this work, to be used as a useful tool for pollutant phytotoxicity screening. For validation, the performance of the microplate algal growth-inhibition assay was first compared with the standard flask assay for the toxicity testing of five reference toxicants (copper(II) sulfate, zinc sulfate, potassium permanganate, potassium dichromate and 3,5-Dichlorophenol) and six wastewater samples. Statistical evaluation of EC(50) results from both methods demonstrated a good agreement between microplate and flask assays either in testing chemicals (r (2) = 0.975, p &lt; 0.0017) or environmental samples toxicity (r (2) = 0.984, p &lt; 0.0001). In addition, the performance of this algal microplate bioassay was also evaluated in comparison with Lemna test, ISO 20079, for phytotoxicity assessment of 27 wastewater samples from industries and treatment plants. The results showed that the algal test was more sensitive for most of the samples, but a significant agreement between both tests was observed (r (2) = 0.644, p &lt; 0.0001). In conclusion, this miniaturized test can be a good tool to include in a battery of tests for phytotoxicity screening of a wide range of chemicals and environmental samples, with the advantage of requiring low sample volumes for the test, allowing large numbers of samples to be tested, and generating low volumes of waste.","Performance of a miniaturized algal bioassay in phytotoxicity screening Abs: A miniaturized and low-cost algal growth-inhibition assay, with Pseudokirchneriella subcapitata, based on the standard ISO 8692 and using 96-well microplates, was tested and optimized in this work, to be used as a useful tool for pollutant phytotoxicity screening. For validation, the performance of the microplate algal growth-inhibition assay was first compared with the standard flask assay for the toxicity testing of five reference toxicants (copper(II) sulfate, zinc sulfate, potassium permanganate, potassium dichromate and 3,5-Dichlorophenol) and six wastewater samples. Statistical evaluation of EC(50) results from both methods demonstrated a good agreement between microplate and flask assays either in testing chemicals (r (2) = 0.975, p &lt; 0.0017) or environmental samples toxicity (r (2) = 0.984, p &lt; 0.0001). In addition, the performance of this algal microplate bioassay was also evaluated in comparison with Lemna test, ISO 20079, for phytotoxicity assessment of 27 wastewater samples from industries and treatment plants. The results showed that the algal test was more sensitive for most of the samples, but a significant agreement between both tests was observed (r (2) = 0.644, p &lt; 0.0001). In conclusion, this miniaturized test can be a good tool to include in a battery of tests for phytotoxicity screening of a wide range of chemicals and environmental samples, with the advantage of requiring low sample volumes for the test, allowing large numbers of samples to be tested, and generating low volumes of waste."
1234231,Schulz et al. 2008,[Disseminated granulomatous type IV reaction after a tattoo],"Localized type-IV allergies to tattoo dyes are quite common. p-Phenylenediamine, which is used as a black pigment in temporary henna tattoos, is a particularly potent allergen. Generalized type IV reactions are very rare, however. Disseminated granulomatous reactions on tattoo dyes have so far not been reported in the literature. We describe the case of a 54-year-old female patient who had such a reaction pattern after a tattoo owing to a previously unknown sensitization to potassium dichromate.","[Disseminated granulomatous type IV reaction after a tattoo] Abs: Localized type-IV allergies to tattoo dyes are quite common. p-Phenylenediamine, which is used as a black pigment in temporary henna tattoos, is a particularly potent allergen. Generalized type IV reactions are very rare, however. Disseminated granulomatous reactions on tattoo dyes have so far not been reported in the literature. We describe the case of a 54-year-old female patient who had such a reaction pattern after a tattoo owing to a previously unknown sensitization to potassium dichromate."
1234230,Huang et al. 2005,An efficient and selective solvent-free oxidation of alcohols by shaking with chromium trioxide supported on aluminium silicate,A selective oxidation of primary alcohols to the corresponding aldehydes by shaking with chromium trioxide supported on aluminium silicate at room temperature under solvent free conditions is reported. This new procedure can also oxidise secondary alcohols.,An efficient and selective solvent-free oxidation of alcohols by shaking with chromium trioxide supported on aluminium silicate Abs: A selective oxidation of primary alcohols to the corresponding aldehydes by shaking with chromium trioxide supported on aluminium silicate at room temperature under solvent free conditions is reported. This new procedure can also oxidise secondary alcohols.
1234229,Elmaaty and  Castle 2005,Chromate oxidation of alpha-nitro alcohols to alpha-nitro ketones: significant improvements to a classic method,A series of eight alkyl and aryl alpha-nitro ketones were prepared by the potassium dichromate oxidation of the corresponding nitro alcohols. Short reaction times allowed for the easy isolation of pure nitro ketones that are devoid of starting materials and/or other oxidation side products.,Chromate oxidation of alpha-nitro alcohols to alpha-nitro ketones: significant improvements to a classic method Abs: A series of eight alkyl and aryl alpha-nitro ketones were prepared by the potassium dichromate oxidation of the corresponding nitro alcohols. Short reaction times allowed for the easy isolation of pure nitro ketones that are devoid of starting materials and/or other oxidation side products.
1234228,Warshaw et al. 2007,"Shoe allergens: retrospective analysis of cross-sectional data from the north american contact dermatitis group, 2001-2004","<strong>BACKGROUND: </strong>Chemicals used in leather tanning, rubber processing, and/or adhesives are the most often-cited culprits in footwear dermatitis. Patch testing patients with suspected shoe dermatitis is essential for diagnosis and management.<br /><br /><strong>OBJECTIVES: </strong>The four goals for this study were to (1) determine the frequency of allergens associated with a shoe source in North American Contact Dermatitis Group (NACDG) patients with footwear allergic contact dermatitis; (2) compare these results to allergen frequencies from other published studies; (3) quantify the number of shoe-related reactions that were not identified with the NACDG standard series; and (4) identify relevant allergens not included on the NACDG standard series, based on data from other published studies.<br /><br /><strong>METHODS: </strong>The NACDG patch-tested 10,061 patients between 2001 and 2004. Data were retrospectively analyzed by (1) allergen source coded as &quot;shoe,&quot; (2) site of dermatitis as &quot;feet,&quot; and (3) diagnosis of &quot;allergic contact dermatitis.&quot;<br /><br /><strong>RESULTS: </strong>Among the 109 NACDG patients with allergic contact dermatitis (ACD) of the foot and a shoe source of allergens, p-tertiary butylphenol formaldehyde resin, an adhesive, was the most common allergen, accounting for 24.7% of positive patch-test results, followed by potassium dichromate (17.5%) and carba mix (11.7%). When the data were examined according to groups of allergens, rubber chemicals (40.4%) were the most frequent allergens, followed by adhesives (32.5%), and leather components (20.1%). When data from published studies were pooled, potassium dichromate (31.5%) was the most frequent allergen, followed by p-tertiary butylphenol formaldehyde resin (17.1%) and cobalt chloride (12.9%). NACDG patients were statistically more likely to have positive patch-test reactions to p-tertiary butylphenol formaldehyde resin and statistically less likely to have a positive patch-test reaction to potassium dichromate than patients represented in pooled data from past studies. Nineteen (17.4%) of the 109 NACDG patients with ACD of the foot and a shoe source of allergens were identified as having a shoe source of a relevant allergen not included in the NACDG standard series.<br /><br /><strong>CONCLUSIONS: </strong>In NACDG patients, the most common individual shoe allergen was p-tertiary butylphenol formaldehyde resin. As a group, rubber chemicals were most common, a finding consistent with those of other studies.","Shoe allergens: retrospective analysis of cross-sectional data from the north american contact dermatitis group, 2001-2004 Abs: <strong>BACKGROUND: </strong>Chemicals used in leather tanning, rubber processing, and/or adhesives are the most often-cited culprits in footwear dermatitis. Patch testing patients with suspected shoe dermatitis is essential for diagnosis and management.<br /><br /><strong>OBJECTIVES: </strong>The four goals for this study were to (1) determine the frequency of allergens associated with a shoe source in North American Contact Dermatitis Group (NACDG) patients with footwear allergic contact dermatitis; (2) compare these results to allergen frequencies from other published studies; (3) quantify the number of shoe-related reactions that were not identified with the NACDG standard series; and (4) identify relevant allergens not included on the NACDG standard series, based on data from other published studies.<br /><br /><strong>METHODS: </strong>The NACDG patch-tested 10,061 patients between 2001 and 2004. Data were retrospectively analyzed by (1) allergen source coded as &quot;shoe,&quot; (2) site of dermatitis as &quot;feet,&quot; and (3) diagnosis of &quot;allergic contact dermatitis.&quot;<br /><br /><strong>RESULTS: </strong>Among the 109 NACDG patients with allergic contact dermatitis (ACD) of the foot and a shoe source of allergens, p-tertiary butylphenol formaldehyde resin, an adhesive, was the most common allergen, accounting for 24.7% of positive patch-test results, followed by potassium dichromate (17.5%) and carba mix (11.7%). When the data were examined according to groups of allergens, rubber chemicals (40.4%) were the most frequent allergens, followed by adhesives (32.5%), and leather components (20.1%). When data from published studies were pooled, potassium dichromate (31.5%) was the most frequent allergen, followed by p-tertiary butylphenol formaldehyde resin (17.1%) and cobalt chloride (12.9%). NACDG patients were statistically more likely to have positive patch-test reactions to p-tertiary butylphenol formaldehyde resin and statistically less likely to have a positive patch-test reaction to potassium dichromate than patients represented in pooled data from past studies. Nineteen (17.4%) of the 109 NACDG patients with ACD of the foot and a shoe source of allergens were identified as having a shoe source of a relevant allergen not included in the NACDG standard series.<br /><br /><strong>CONCLUSIONS: </strong>In NACDG patients, the most common individual shoe allergen was p-tertiary butylphenol formaldehyde resin. As a group, rubber chemicals were most common, a finding consistent with those of other studies."
1234227,Yam-Canul et al. 2008,Nordihydroguaiaretic acid attenuates potassium dichromate-induced oxidative stress and nephrotoxicity,"Larrea tridentata also known as Creosote bush, Larrea, chaparral, greasewood or gobernadora has been used in the folk medicine for the treatment of several illnesses. The primary product that is present at high concentrations in the leaves from this plant is nordihydroguaiaretic acid (NDGA) which is a powerful antioxidant. On the other hand, potassium dichromate (K(2)Cr(2)O(7))-induced nephrotoxicity is associated with oxidative stress. The aim of this work was to study the effect of NDGA on K(2)Cr(2)O(7)-induced nephrotoxicity and oxidative stress. Nephrotoxicity was induced by a single injection of K(2)Cr(2)O(7) (15 mg/Kg). A group of K(2)Cr(2)O(7)-treated rats was administered NDGA by mini osmotic pumps (17 mg/Kg/day). The results show that NDGA was able to ameliorate the structural and functional renal damage evaluated by histopathological analysis and by measuring proteinuria, urinary excretion of N-acetyl-beta-d-glucosaminidase, serum creatinine, and serum glutathione peroxidase activity. In addition, immunostaining of 4-hydroxy-2-nonenal and 3-nitrotyrosine, markers of oxidative and nitrosative stress, respectively, was ameliorated by the NDGA treatment. These data strongly suggest that the antioxidant properties of NDGA are involved in its renoprotective effect in K(2)Cr(2)O(7)-treated rats.","Nordihydroguaiaretic acid attenuates potassium dichromate-induced oxidative stress and nephrotoxicity Abs: Larrea tridentata also known as Creosote bush, Larrea, chaparral, greasewood or gobernadora has been used in the folk medicine for the treatment of several illnesses. The primary product that is present at high concentrations in the leaves from this plant is nordihydroguaiaretic acid (NDGA) which is a powerful antioxidant. On the other hand, potassium dichromate (K(2)Cr(2)O(7))-induced nephrotoxicity is associated with oxidative stress. The aim of this work was to study the effect of NDGA on K(2)Cr(2)O(7)-induced nephrotoxicity and oxidative stress. Nephrotoxicity was induced by a single injection of K(2)Cr(2)O(7) (15 mg/Kg). A group of K(2)Cr(2)O(7)-treated rats was administered NDGA by mini osmotic pumps (17 mg/Kg/day). The results show that NDGA was able to ameliorate the structural and functional renal damage evaluated by histopathological analysis and by measuring proteinuria, urinary excretion of N-acetyl-beta-d-glucosaminidase, serum creatinine, and serum glutathione peroxidase activity. In addition, immunostaining of 4-hydroxy-2-nonenal and 3-nitrotyrosine, markers of oxidative and nitrosative stress, respectively, was ameliorated by the NDGA treatment. These data strongly suggest that the antioxidant properties of NDGA are involved in its renoprotective effect in K(2)Cr(2)O(7)-treated rats."
1234226,Ganesh et al. 2008,Chromium stress induced alterations in biochemical and enzyme metabolism in aquatic and terrestrial plants,"Water is seriously polluted by the discharge of various industrial wastewater containing heavy metals. Among them, chromium is considered to be toxic to living organisms and it is released mostly from tanneries. The chromium-contaminated water is discharged into nearby water bodies and it affects both aquatic and terrestrial plants. So the present experiment was conducted with an aquatic plant, water lettuce (Pistia stratiotes L.) and a terrestrial plant soybean (Glycine max L. Merr.). They were treated with different concentrations (0, 5, 10, 25, 50, 100 and 200mg/L) of potassium dichromate solution. The biochemical parameters such as total chlorophyll, carotenoid, protein and amino acid content and the enzymatic activities like catalase and peroxidase were estimated. The accumulation of chromium was also analysed in both the plants. All the biochemical contents and enzyme activities of water lettuce and soybean seedlings showed a great variation with respect to the increase in chromium concentrations. The accumulation of chromium increased gradually with the increase of chromium concentrations. Total inhibition of all the parameters were observed at 300 mg/L chromium concentration. The terrestrial plant soybean was sensitive than the aquatic plant water lettuce towards chromium stress.","Chromium stress induced alterations in biochemical and enzyme metabolism in aquatic and terrestrial plants Abs: Water is seriously polluted by the discharge of various industrial wastewater containing heavy metals. Among them, chromium is considered to be toxic to living organisms and it is released mostly from tanneries. The chromium-contaminated water is discharged into nearby water bodies and it affects both aquatic and terrestrial plants. So the present experiment was conducted with an aquatic plant, water lettuce (Pistia stratiotes L.) and a terrestrial plant soybean (Glycine max L. Merr.). They were treated with different concentrations (0, 5, 10, 25, 50, 100 and 200mg/L) of potassium dichromate solution. The biochemical parameters such as total chlorophyll, carotenoid, protein and amino acid content and the enzymatic activities like catalase and peroxidase were estimated. The accumulation of chromium was also analysed in both the plants. All the biochemical contents and enzyme activities of water lettuce and soybean seedlings showed a great variation with respect to the increase in chromium concentrations. The accumulation of chromium increased gradually with the increase of chromium concentrations. Total inhibition of all the parameters were observed at 300 mg/L chromium concentration. The terrestrial plant soybean was sensitive than the aquatic plant water lettuce towards chromium stress."
1234224,Püllen et al. 2008,"The role of preparation technique, culture media and incubation time for embryonation of Heterakis gallinarum eggs","The importance of preparation technique, culture media and incubation time in the embryonation of the infective egg stages of the intestinal nematode parasite Heterakis gallinarum was studied. Mature H. gallinarum worms were isolated from the caeca of infected chickens and separated by sex. In a first experiment intact female worms were kept for the development of their eggs in four different media (0.5% formalin, 2% formalin, 0.1 N sulphuric acid, 0.1% potassium dichromate) and incubated under constant temperature (20-22 degrees C) for 2, 4, 6 or 8 weeks. Afterwards the body of the worms were ruptured and the numbers of unembryonated and embryonated eggs were determined using a McMaster egg counting chamber, and the percentage of embryonated eggs was calculated. After 8 weeks of incubation in 0.5% formalin, 0.1 N sulphuric acid or 0.1% potassium dichromate 27.6%, 26.7% and 29.4% of the eggs, respectively, embryonated into third stage larvae (p &gt; 0.05). In contrast, incubation in 2% formalin resulted in an embryonation of 18.6% only (p &lt; 0.05). In a second experiment H. gallinarum eggs were directly harvested from worm uteri and cultivated afterwards in different media (2% formalin, 0.1 N sulphuric acid, 0.1% potassium dichromate) at 20 to 22 degrees C for 6 weeks. An incubation of isolated eggs in 2.0% formalin or 0.1% potassium dichromate during 6 weeks resulted in a significantly higher percentage of embryonation in comparison to the incubation of intact worms (first experiment). The results suggest that preparation technique, media and time of incubation has an essential influence on the development rate of H. gallinarum eggs.","The role of preparation technique, culture media and incubation time for embryonation of Heterakis gallinarum eggs Abs: The importance of preparation technique, culture media and incubation time in the embryonation of the infective egg stages of the intestinal nematode parasite Heterakis gallinarum was studied. Mature H. gallinarum worms were isolated from the caeca of infected chickens and separated by sex. In a first experiment intact female worms were kept for the development of their eggs in four different media (0.5% formalin, 2% formalin, 0.1 N sulphuric acid, 0.1% potassium dichromate) and incubated under constant temperature (20-22 degrees C) for 2, 4, 6 or 8 weeks. Afterwards the body of the worms were ruptured and the numbers of unembryonated and embryonated eggs were determined using a McMaster egg counting chamber, and the percentage of embryonated eggs was calculated. After 8 weeks of incubation in 0.5% formalin, 0.1 N sulphuric acid or 0.1% potassium dichromate 27.6%, 26.7% and 29.4% of the eggs, respectively, embryonated into third stage larvae (p &gt; 0.05). In contrast, incubation in 2% formalin resulted in an embryonation of 18.6% only (p &lt; 0.05). In a second experiment H. gallinarum eggs were directly harvested from worm uteri and cultivated afterwards in different media (2% formalin, 0.1 N sulphuric acid, 0.1% potassium dichromate) at 20 to 22 degrees C for 6 weeks. An incubation of isolated eggs in 2.0% formalin or 0.1% potassium dichromate during 6 weeks resulted in a significantly higher percentage of embryonation in comparison to the incubation of intact worms (first experiment). The results suggest that preparation technique, media and time of incubation has an essential influence on the development rate of H. gallinarum eggs."
1234223,Marchese et al. 2008,Accumulation and elimination of chromium by freshwater species exposed to spiked sediments,"The bioaccumulation and elimination capacity of chromium were examined in four freshwater species: the submersed aquatic plant Ceratophyllum demersum (Ceratophyllaceae), the oligochaete Limnodrilus udekemianus (Tubificidae), the crab Zilchiopsis collastinensis (Decapoda), and the fish Cnesterodon decemmaculatus (Poeciliidae). All of the species were exposed simultaneously to sediments spiked with Cr (K(2)Cr(2)O(7)) at different concentrations for 28 days, followed by 7 days without Cr to evaluate the concentration of residual Cr. We found that Cr accumulated in the tissues of all four species. The highest bioconcentration factor obtained for each species is as follows: C. demersum, 718.66 (+/-272.91); L. udekemianus, 172.55 (+/-80.8), Z. collastinensis, 67.72 (+/-35.4); C. decemmaculatus, 23.11 (+/-12.82), all at 28 days of exposure.","Accumulation and elimination of chromium by freshwater species exposed to spiked sediments Abs: The bioaccumulation and elimination capacity of chromium were examined in four freshwater species: the submersed aquatic plant Ceratophyllum demersum (Ceratophyllaceae), the oligochaete Limnodrilus udekemianus (Tubificidae), the crab Zilchiopsis collastinensis (Decapoda), and the fish Cnesterodon decemmaculatus (Poeciliidae). All of the species were exposed simultaneously to sediments spiked with Cr (K(2)Cr(2)O(7)) at different concentrations for 28 days, followed by 7 days without Cr to evaluate the concentration of residual Cr. We found that Cr accumulated in the tissues of all four species. The highest bioconcentration factor obtained for each species is as follows: C. demersum, 718.66 (+/-272.91); L. udekemianus, 172.55 (+/-80.8), Z. collastinensis, 67.72 (+/-35.4); C. decemmaculatus, 23.11 (+/-12.82), all at 28 days of exposure."
1234222,Bornstein et al. 2008,Isospora orlovi infection in suckling dromedary camel calves (Camelus dromedarius) in Kenya,"Outbreaks of isosporosis in young suckling dromedary camel calves (Camelus dromedarius) in Dubai, UAE and in Kenya were recently described. In the former outbreak the pathogen was shown to be Isospora orlovi by morphological features and was later characterized molecularly. In the present study, we have made a longitudinal investigation of 159 suckling dromedary calves &lt; or =12 weeks of age belonging to 8 ranched camel herds (M1) in Northern Kenya. The study was carried out during 18 months. In three of the herds frequent samples were taken irregularly every 1-6 weeks. All calves &lt; or =12 weeks of age present in the respective herds were sampled during the visits. In addition, 91 calves of the same age group but belonging to 42 pastoral herds (M2) in Northern Kenya were point sampled at convenience. Faecal samples from each calf were taken and the faeces were investigated for coccidia. Samples found with coccidian oocysts were suspended in a 2% potassium dichromate solution. Isospora sp. was identified and samples with relatively high numbers of Isospora sp. were analysed molecularly. The SSU rRNA gene and internal transcribed spacer 1 (ITS1) were amplified with primers complementary to conserved regions of the SSU rRNA gene in eukaryotes as well as a conserved part of the 5.8S rRNA gene of Eimeria. A relatively high number of the calves exhibited diarrhoea, 30.2% and 41.8% in the M1 and M2 herds, respectively. Isospora sp. was only found in diarrhoeic calves or in calves convalescent from recent scouring periods. No calf &gt;8 weeks of age was found to be excreting Isospora sp. The parasite was only found in calves &lt; or =4 weeks of age in the M1 herds and in the M2 herds in calves &lt;8 weeks of age. Of the M1 and M2 calves exhibiting diarrhoea, 20.8% and 26.3% excreted Isospora sp., respectively. Morphologically the Isospora sp. was similar to I. orlovi and sequence analysis of the SSU rRNA gene from four Kenyan isolates (unfortunately only from the pastoral herds, M2) and ITS 1 segments from three of the isolates from Kenya and one from Dubai, confirmed that the Isospora isolates belonged to the species I. orlovi, and that the sequences were similar to the Dubai isolates.","Isospora orlovi infection in suckling dromedary camel calves (Camelus dromedarius) in Kenya Abs: Outbreaks of isosporosis in young suckling dromedary camel calves (Camelus dromedarius) in Dubai, UAE and in Kenya were recently described. In the former outbreak the pathogen was shown to be Isospora orlovi by morphological features and was later characterized molecularly. In the present study, we have made a longitudinal investigation of 159 suckling dromedary calves &lt; or =12 weeks of age belonging to 8 ranched camel herds (M1) in Northern Kenya. The study was carried out during 18 months. In three of the herds frequent samples were taken irregularly every 1-6 weeks. All calves &lt; or =12 weeks of age present in the respective herds were sampled during the visits. In addition, 91 calves of the same age group but belonging to 42 pastoral herds (M2) in Northern Kenya were point sampled at convenience. Faecal samples from each calf were taken and the faeces were investigated for coccidia. Samples found with coccidian oocysts were suspended in a 2% potassium dichromate solution. Isospora sp. was identified and samples with relatively high numbers of Isospora sp. were analysed molecularly. The SSU rRNA gene and internal transcribed spacer 1 (ITS1) were amplified with primers complementary to conserved regions of the SSU rRNA gene in eukaryotes as well as a conserved part of the 5.8S rRNA gene of Eimeria. A relatively high number of the calves exhibited diarrhoea, 30.2% and 41.8% in the M1 and M2 herds, respectively. Isospora sp. was only found in diarrhoeic calves or in calves convalescent from recent scouring periods. No calf &gt;8 weeks of age was found to be excreting Isospora sp. The parasite was only found in calves &lt; or =4 weeks of age in the M1 herds and in the M2 herds in calves &lt;8 weeks of age. Of the M1 and M2 calves exhibiting diarrhoea, 20.8% and 26.3% excreted Isospora sp., respectively. Morphologically the Isospora sp. was similar to I. orlovi and sequence analysis of the SSU rRNA gene from four Kenyan isolates (unfortunately only from the pastoral herds, M2) and ITS 1 segments from three of the isolates from Kenya and one from Dubai, confirmed that the Isospora isolates belonged to the species I. orlovi, and that the sequences were similar to the Dubai isolates."
1234221,Lushchak et al. 2008,The effect of potassium dichromate on free radical processes in goldfish: possible protective role of glutathione,"The effects of 96 h exposure to Cr(6+) (added as potassium dichromate) on the status of antioxidant defenses and markers of oxidative damage were evaluated in three tissues of goldfish, Carassius auratus. Fish exposure to high dichromate concentrations, 10 and 50mg/l, increased protein carbonyl levels in brain and liver, but not in kidney. Chromium exposure also increased concentrations of lipid peroxides in brain (at 5mg/l) and liver (10mg/l), but not in kidney. The concentrations of reduced glutathione (GSH) were higher in the liver of goldfish treated with 5-50mg/l Cr(6+) than in controls, but in kidney only the 5mg/l-treated group showed increased GSH levels. Dichromate at 1mg/l increased the concentration of oxidized glutathione (GSSG) in liver and kidney by 80% and 60%, respectively, whereas at 10 and 50mg/l the levels of GSSG decreased by 50% in kidney. These results indicate that the dichromate concentrations used induced oxidation of lipids and proteins in goldfish tissues in a concentration- and tissue-specific manner. Also, the redox status of fish tissues was affected in a concentration- and tissue-specific manner. The activities of glutathione reductase increased in all three tissues in response to dichromate treatment, increasing by approximately 2-fold in brain and liver in goldfish treated with 50mg/l Cr(6+). Dichromate treatment did not change the activities of SOD, catalase or GST in brain, but reduced the activities of SOD in liver and kidney, and catalase in liver. The results suggest that the glutathione system may be responsible for protecting against the deleterious effects of dichromate in fish and indicate the possible development of an adaptive response during the 96 h treatment with the toxicant.","The effect of potassium dichromate on free radical processes in goldfish: possible protective role of glutathione Abs: The effects of 96 h exposure to Cr(6+) (added as potassium dichromate) on the status of antioxidant defenses and markers of oxidative damage were evaluated in three tissues of goldfish, Carassius auratus. Fish exposure to high dichromate concentrations, 10 and 50mg/l, increased protein carbonyl levels in brain and liver, but not in kidney. Chromium exposure also increased concentrations of lipid peroxides in brain (at 5mg/l) and liver (10mg/l), but not in kidney. The concentrations of reduced glutathione (GSH) were higher in the liver of goldfish treated with 5-50mg/l Cr(6+) than in controls, but in kidney only the 5mg/l-treated group showed increased GSH levels. Dichromate at 1mg/l increased the concentration of oxidized glutathione (GSSG) in liver and kidney by 80% and 60%, respectively, whereas at 10 and 50mg/l the levels of GSSG decreased by 50% in kidney. These results indicate that the dichromate concentrations used induced oxidation of lipids and proteins in goldfish tissues in a concentration- and tissue-specific manner. Also, the redox status of fish tissues was affected in a concentration- and tissue-specific manner. The activities of glutathione reductase increased in all three tissues in response to dichromate treatment, increasing by approximately 2-fold in brain and liver in goldfish treated with 50mg/l Cr(6+). Dichromate treatment did not change the activities of SOD, catalase or GST in brain, but reduced the activities of SOD in liver and kidney, and catalase in liver. The results suggest that the glutathione system may be responsible for protecting against the deleterious effects of dichromate in fish and indicate the possible development of an adaptive response during the 96 h treatment with the toxicant."
1234220,Samaratunga et al. 2008,"Extraction of chromium(VI) by salting-out with a homogeneous, mixed solvent of water and 2-propanol: a laboratory study","<strong>BACKGROUND, AIMS AND SCOPE: </strong>Chromium enters into the aquatic environment as a result of effluent discharge from steel works, electroplating, leather tanning industries and chemical industries. As the Cr(VI) is very harmful to living organisms, it should be quickly removed from the environment when it happens to be contaminated. Therefore, the aim of this laboratory research was to develop a rapid, simple and adaptable solvent extraction system to quantitatively remove Cr(VI) from polluted waters.<br /><br /><strong>METHODS: </strong>Aqueous salt-solutions containing Cr(VI) as CrO4(2-) at ppm level (4-6 ppm) were prepared. Equal volumes (5 ml) of aqueous and organic (2-PrOH) phases were mixed in a 10 ml centrifuge tube for 15 min, centrifuged and separated. Concentrations of Cr(VI), in both the aqueous and organic phases, were determined by atomic absorption spectrometry. The effects of salt and acid concentrations, and phase-contact time on the extraction of Cr(VI) were investigated. In addition, the extraction of Cr(VI) was assessed in the presence of tetramethylammonium chloride (TMAC) in 2-PrOH phase. Effects of some other metals, (Cd(II), Co(II), Cu(II), Ni(II) and Zn(II)), on the extraction of Cr(VI) were also investigated.<br /><br /><strong>RESULTS AND DISCUSSION: </strong>The Cr(VI) at ppm level was extracted quantitatively by salting-out the homogeneous system of water and 2-propanol(2-PrOH) using chloride salts, namely CaCl2 or NaCl, under acidic chloride media. The extracted chemical species of Cr(VI) was confirmed to be the CrO3Cl-. The ion-pair complex extracted into the organic phase was rationalized as the solvated ion-pair complex of [2-PrOH2+, CrO3Cl-]. The complex was no longer stable. It implied the reaction between extracted species. Studies revealed that salts and acid directly participated in the formation of the above complex. Use of extracting agents (TMAC) didn't show any significant effect on the extraction of Cr(VI) under high salting-out conditions. There is no significant interference effect on the extraction of Cr(VI) by the presence of other metals. The Cr(VI) in the organic phase was back-extracted using an aqueous ammonia solution (1.6 mol dm(-3)) containing 3 mol dm(-3) NaCl. The extraction mechanism of Cr(VI) is also discussed.<br /><br /><strong>CONCLUSIONS: </strong>Salting-out of homogeneous mixed solvent of 2-propanol can be employed to extract Cr(VI) quantitatively, as an ion-pair of [2-PrOH2+ * CrO3Cl-] solvated by 2-PrOH molecules. Then, the complex becomes 'solvent-like' and is readily separated into the organic phase. The increase of Cl- ion concentration in the aqueous phase favors the extraction. The 2-PrOH, salts and acid play important roles in the extraction process. There is no need to use an extracting agent at a high salting-out condition.<br /><br /><strong>RECOMMENDATIONS AND PERSPECTIVES: </strong>Chromium(VI) must be quickly removed before it enters into the natural cycle. As the 2-PrOH is water-miscible in any proportion, ion-pairing between 2-PrOH2+ and CrO3Cl- becomes very fast. As a result, Cr(VI) can easily be extracted. Therefore, the method is recommended as a simple, rapid and adaptable method to quickly separate Cr(VI) from aqueous samples.","Extraction of chromium(VI) by salting-out with a homogeneous, mixed solvent of water and 2-propanol: a laboratory study Abs: <strong>BACKGROUND, AIMS AND SCOPE: </strong>Chromium enters into the aquatic environment as a result of effluent discharge from steel works, electroplating, leather tanning industries and chemical industries. As the Cr(VI) is very harmful to living organisms, it should be quickly removed from the environment when it happens to be contaminated. Therefore, the aim of this laboratory research was to develop a rapid, simple and adaptable solvent extraction system to quantitatively remove Cr(VI) from polluted waters.<br /><br /><strong>METHODS: </strong>Aqueous salt-solutions containing Cr(VI) as CrO4(2-) at ppm level (4-6 ppm) were prepared. Equal volumes (5 ml) of aqueous and organic (2-PrOH) phases were mixed in a 10 ml centrifuge tube for 15 min, centrifuged and separated. Concentrations of Cr(VI), in both the aqueous and organic phases, were determined by atomic absorption spectrometry. The effects of salt and acid concentrations, and phase-contact time on the extraction of Cr(VI) were investigated. In addition, the extraction of Cr(VI) was assessed in the presence of tetramethylammonium chloride (TMAC) in 2-PrOH phase. Effects of some other metals, (Cd(II), Co(II), Cu(II), Ni(II) and Zn(II)), on the extraction of Cr(VI) were also investigated.<br /><br /><strong>RESULTS AND DISCUSSION: </strong>The Cr(VI) at ppm level was extracted quantitatively by salting-out the homogeneous system of water and 2-propanol(2-PrOH) using chloride salts, namely CaCl2 or NaCl, under acidic chloride media. The extracted chemical species of Cr(VI) was confirmed to be the CrO3Cl-. The ion-pair complex extracted into the organic phase was rationalized as the solvated ion-pair complex of [2-PrOH2+, CrO3Cl-]. The complex was no longer stable. It implied the reaction between extracted species. Studies revealed that salts and acid directly participated in the formation of the above complex. Use of extracting agents (TMAC) didn't show any significant effect on the extraction of Cr(VI) under high salting-out conditions. There is no significant interference effect on the extraction of Cr(VI) by the presence of other metals. The Cr(VI) in the organic phase was back-extracted using an aqueous ammonia solution (1.6 mol dm(-3)) containing 3 mol dm(-3) NaCl. The extraction mechanism of Cr(VI) is also discussed.<br /><br /><strong>CONCLUSIONS: </strong>Salting-out of homogeneous mixed solvent of 2-propanol can be employed to extract Cr(VI) quantitatively, as an ion-pair of [2-PrOH2+ * CrO3Cl-] solvated by 2-PrOH molecules. Then, the complex becomes 'solvent-like' and is readily separated into the organic phase. The increase of Cl- ion concentration in the aqueous phase favors the extraction. The 2-PrOH, salts and acid play important roles in the extraction process. There is no need to use an extracting agent at a high salting-out condition.<br /><br /><strong>RECOMMENDATIONS AND PERSPECTIVES: </strong>Chromium(VI) must be quickly removed before it enters into the natural cycle. As the 2-PrOH is water-miscible in any proportion, ion-pairing between 2-PrOH2+ and CrO3Cl- becomes very fast. As a result, Cr(VI) can easily be extracted. Therefore, the method is recommended as a simple, rapid and adaptable method to quickly separate Cr(VI) from aqueous samples."
1234219,Yam-Canul et al. 2008,"PJ34, a poly adenosine diphosphate-ribose polymerase inhibitor, attenuates chromate-induced nephrotoxicity","Potassium dichromate (K(2)Cr(2)O(7))-induced nephrotoxicity is associated with oxidative stress. In addition, the activation of the polyadenosine diphosphate-ribose [poly(ADP-ribose)] polymerase-1 (PARP-1) plays a role in the pathophysiology of some diseases associated with oxidative stress. To clarify the potential role of PARP-1 in this experimental model, N-(6-oxo-5,6-dihydro-phenanthridin-2-yl)-N,N-dimethyacetamide HCl (PJ34), a highly specific inhibitor of this enzyme, was used. Nephrotoxicity was induced in rats by a single sc injection of K(2)Cr(2)O(7); studies were performed 2 days later. PJ34 was given intraperitoneally (15 mg/kg) 1 hr before and 1, 5, 24, 26, 31 and 46 hr after K(2)Cr(2)O(7) injection. Nephrotoxicity was evaluated by histological analysis and by measuring blood urea nitrogen, serum creatinine, serum glutathione peroxidase activity and urinary excretion of N-acetyl-beta-D-glucosaminidase. PARP-1 activation was evaluated by the immunostaining of poly(ADP-ribose). In addition, the following markers of oxidative stress were evaluated: 3-nitrotyrosine, 4-hydroxy-2-nonenal, malondialdehyde and protein carbonyl content. K(2)Cr(2)O(7) increased poly(ADP-ribose) content suggesting the PARP-1 activation in this model. PJ34 significantly ameliorated the K(2)Cr(2)O(7)-induced: (i) nephrotoxicity, (ii) poly(ADP-ribose) accumulation and (iii) oxidative stress. It is concluded that PARP-1 is activated and involved, at least in part, in K(2)Cr(2)O(7)-induced nephrotoxicity in rats.","PJ34, a poly adenosine diphosphate-ribose polymerase inhibitor, attenuates chromate-induced nephrotoxicity Abs: Potassium dichromate (K(2)Cr(2)O(7))-induced nephrotoxicity is associated with oxidative stress. In addition, the activation of the polyadenosine diphosphate-ribose [poly(ADP-ribose)] polymerase-1 (PARP-1) plays a role in the pathophysiology of some diseases associated with oxidative stress. To clarify the potential role of PARP-1 in this experimental model, N-(6-oxo-5,6-dihydro-phenanthridin-2-yl)-N,N-dimethyacetamide HCl (PJ34), a highly specific inhibitor of this enzyme, was used. Nephrotoxicity was induced in rats by a single sc injection of K(2)Cr(2)O(7); studies were performed 2 days later. PJ34 was given intraperitoneally (15 mg/kg) 1 hr before and 1, 5, 24, 26, 31 and 46 hr after K(2)Cr(2)O(7) injection. Nephrotoxicity was evaluated by histological analysis and by measuring blood urea nitrogen, serum creatinine, serum glutathione peroxidase activity and urinary excretion of N-acetyl-beta-D-glucosaminidase. PARP-1 activation was evaluated by the immunostaining of poly(ADP-ribose). In addition, the following markers of oxidative stress were evaluated: 3-nitrotyrosine, 4-hydroxy-2-nonenal, malondialdehyde and protein carbonyl content. K(2)Cr(2)O(7) increased poly(ADP-ribose) content suggesting the PARP-1 activation in this model. PJ34 significantly ameliorated the K(2)Cr(2)O(7)-induced: (i) nephrotoxicity, (ii) poly(ADP-ribose) accumulation and (iii) oxidative stress. It is concluded that PARP-1 is activated and involved, at least in part, in K(2)Cr(2)O(7)-induced nephrotoxicity in rats."
1234218,Vignati et al. 2008,Temporal decrease of trivalent chromium concentration in a standardized algal culture medium: experimental results and implications for toxicity evaluation,"The fate of two trivalent chromium salts (nitrate and chloride) in ISO algal culture medium was followed over 72 h; i.e., the typical duration of algal toxicity tests. Fifty percent of the initial Cr spikes was lost from the solutions by 24 h, with losses up to 90% after 72 h. Monitoring of the temporal variability of Cr(III) concentrations in algal culture media appears necessary to better characterize the toxicity of trivalent chromium to algae.","Temporal decrease of trivalent chromium concentration in a standardized algal culture medium: experimental results and implications for toxicity evaluation Abs: The fate of two trivalent chromium salts (nitrate and chloride) in ISO algal culture medium was followed over 72 h; i.e., the typical duration of algal toxicity tests. Fifty percent of the initial Cr spikes was lost from the solutions by 24 h, with losses up to 90% after 72 h. Monitoring of the temporal variability of Cr(III) concentrations in algal culture media appears necessary to better characterize the toxicity of trivalent chromium to algae."
1234217,Matsumoto et al. 2008,"Chemical sensitivity of the male daphnid, Daphnia magna, induced by exposure to juvenile hormone and its analogs","It was reported that males daphnid Daphnia magna that have been induced by methyl farnesoate exposure exhibit higher tolerance to chemical compounds such as potassium dichromate and pentachlorophenol than females. Male neonates are also known to be induced by exposure to juvenile hormone analogs, such as fenoxycarb and pyriproxyfen. If these analogs can be used to produce male progeny, the biological and physiological studies of daphnid male would be progressed since the effects of these analogs were several hundred times higher than that of methyl farnesoate. Therefore, in the present study, it was investigated that the chemical sensitivity of male neonates induced by exposure to juvenile hormone (methyl farnesoate) and its analogs. The minimum concentrations of methyl farnesoate, fenoxycarb and pyriproxyfen to induce 100% male-reproduction were 200nM (50microg/l), 0.23nM (70ng/l) and 0.31nM (100ng/l), respectively. In addition, no reduction of relative reproduction was observed at the juvenoid concentrations in 24h exposure producing 100% male progeny. The median effective concentrations (EC50) of potassium dichromate for immobility of male neonates, established by a standardized method for investigating sensitivity to chemicals, were significantly higher (12-29%) than that of females at least after 24h exposure in all the male neonates induced by juvenoids used in this study (P&lt;0.05). This study demonstrated that the male daphnids induced by exposure to juvenile hormone and its analogs exhibit similar chemical tolerance.","Chemical sensitivity of the male daphnid, Daphnia magna, induced by exposure to juvenile hormone and its analogs Abs: It was reported that males daphnid Daphnia magna that have been induced by methyl farnesoate exposure exhibit higher tolerance to chemical compounds such as potassium dichromate and pentachlorophenol than females. Male neonates are also known to be induced by exposure to juvenile hormone analogs, such as fenoxycarb and pyriproxyfen. If these analogs can be used to produce male progeny, the biological and physiological studies of daphnid male would be progressed since the effects of these analogs were several hundred times higher than that of methyl farnesoate. Therefore, in the present study, it was investigated that the chemical sensitivity of male neonates induced by exposure to juvenile hormone (methyl farnesoate) and its analogs. The minimum concentrations of methyl farnesoate, fenoxycarb and pyriproxyfen to induce 100% male-reproduction were 200nM (50microg/l), 0.23nM (70ng/l) and 0.31nM (100ng/l), respectively. In addition, no reduction of relative reproduction was observed at the juvenoid concentrations in 24h exposure producing 100% male progeny. The median effective concentrations (EC50) of potassium dichromate for immobility of male neonates, established by a standardized method for investigating sensitivity to chemicals, were significantly higher (12-29%) than that of females at least after 24h exposure in all the male neonates induced by juvenoids used in this study (P&lt;0.05). This study demonstrated that the male daphnids induced by exposure to juvenile hormone and its analogs exhibit similar chemical tolerance."
1234215,Levine and  Marcillo 2008,Origin and endpoint of the olfactory nerve fibers: as described by Santiago Ramón y Cajal,"In the late Nineteenth Century, Santiago Ramón y Cajal was able to reproduce an exceptional illustration of the Olfactory Nerve pathway and its myriad of cells, by using the Golgi Method. Dr. Cajal focused intense study on the histology of the nervous system and published a treatise on the olfactory nerve fibers and the distinct peripheral origin and central nervous system endpoint of this unique pathway. The original title of this work is &quot;Origen y terminación de las fibras nerviosas olfatorias&quot; published in 1890. As the original publication is in Spanish, here we provide an English translation allowing present-day English speakers to read these writings. Cajal followed the trajectory of the olfactory nerve fibers as they transitioned between the peripheral and central nervous system and was able to assert that these fibers were not continuous from the olfactory bulb to the bipolar cells that relinquish into the olfactory epithelium, but that the olfactory system was made up of various cell types each having distinct morphologies and functions. This may very well be the first definitive description of the olfactory receptor neurons and the first illustrations of the continuity of these cells throughout the olfactory pathway. These meticulous histological preparations were created by first using Camillo Golgi's potassium dichromate and silver nitrate impregnation method known as &quot;reazione nera&quot; or &quot;black reaction,&quot; where nerve cells, nerve fibers, and neuroglia could be visualized. This study exhibits the structural and functional organization of the mammalian fila olfactoria as it was investigated in centuries past.","Origin and endpoint of the olfactory nerve fibers: as described by Santiago Ramón y Cajal Abs: In the late Nineteenth Century, Santiago Ramón y Cajal was able to reproduce an exceptional illustration of the Olfactory Nerve pathway and its myriad of cells, by using the Golgi Method. Dr. Cajal focused intense study on the histology of the nervous system and published a treatise on the olfactory nerve fibers and the distinct peripheral origin and central nervous system endpoint of this unique pathway. The original title of this work is &quot;Origen y terminación de las fibras nerviosas olfatorias&quot; published in 1890. As the original publication is in Spanish, here we provide an English translation allowing present-day English speakers to read these writings. Cajal followed the trajectory of the olfactory nerve fibers as they transitioned between the peripheral and central nervous system and was able to assert that these fibers were not continuous from the olfactory bulb to the bipolar cells that relinquish into the olfactory epithelium, but that the olfactory system was made up of various cell types each having distinct morphologies and functions. This may very well be the first definitive description of the olfactory receptor neurons and the first illustrations of the continuity of these cells throughout the olfactory pathway. These meticulous histological preparations were created by first using Camillo Golgi's potassium dichromate and silver nitrate impregnation method known as &quot;reazione nera&quot; or &quot;black reaction,&quot; where nerve cells, nerve fibers, and neuroglia could be visualized. This study exhibits the structural and functional organization of the mammalian fila olfactoria as it was investigated in centuries past."
1234214,Lindemann et al. 2008,Detection of chromium allergy by cellular in vitro methods,"<strong>BACKGROUND: </strong>The standard assay for the detection of chromium sensitization, the patch test, does not allow discrimination between patients with and without clinical symptoms of allergy.<br /><br /><strong>OBJECTIVE: </strong>The aim of this study was to prove whether cellular in vitro tests are predictive of chromium allergy.<br /><br /><strong>METHODS: </strong>Chromium-sensitized volunteers with and without clinically manifest allergy and non-sensitized healthy controls (n=37, 19, and 26, respectively) were analysed by cellular in vitro methods using tri- and hexavalent chromium (chromium chloride and potassium dichromate) as stimuli. The results were correlated with clinical and anamnestic data.<br /><br /><strong>RESULTS: </strong>Sensitized individuals with an allergy displayed significantly higher lymphocyte transformation test (LTT) responses than sensitized volunteers without allergy and controls (P&lt;0.05 and P&lt;0.01, respectively). 12.5 microg/mL of chromium chloride and 50 ng/mL of potassium dichromate were found to be optimal to discriminate between sensitized individuals with and without allergy. Combining the results of chromium chloride and potassium dichromate LTT, a positive reaction to at least one of the stimuli was highly predictive of allergy [sensitization with vs. without allergy: Odds ratio (OR)=6.4, P=0.004; sensitization with allergy vs. controls: OR=11.5, P&lt;0.0001]. On the contrary, IFN-gamma, IL-2, IL-4, IL-10, and IL-12 production to the ELISpot, patch test results, sensitization against other metals, and atopy score did not significantly discriminate between sensitization with and without allergy. However, IFN-gamma responses towards chromium chloride were significantly correlated with the strength of patch test reactivity (r=0.49, P=0.002). By IFN-gamma ELISpot, the average precursor cell frequency reactive to trivalent chromium could be defined as 26, 15, and 11 : 10(6) in volunteers with sensitization and allergy, with sensitization without allergy, and controls, respectively.<br /><br /><strong>CONCLUSIONS: </strong>In contrast to the patch test, the LTT appears to be a method that is predictive of chromium allergy.","Detection of chromium allergy by cellular in vitro methods Abs: <strong>BACKGROUND: </strong>The standard assay for the detection of chromium sensitization, the patch test, does not allow discrimination between patients with and without clinical symptoms of allergy.<br /><br /><strong>OBJECTIVE: </strong>The aim of this study was to prove whether cellular in vitro tests are predictive of chromium allergy.<br /><br /><strong>METHODS: </strong>Chromium-sensitized volunteers with and without clinically manifest allergy and non-sensitized healthy controls (n=37, 19, and 26, respectively) were analysed by cellular in vitro methods using tri- and hexavalent chromium (chromium chloride and potassium dichromate) as stimuli. The results were correlated with clinical and anamnestic data.<br /><br /><strong>RESULTS: </strong>Sensitized individuals with an allergy displayed significantly higher lymphocyte transformation test (LTT) responses than sensitized volunteers without allergy and controls (P&lt;0.05 and P&lt;0.01, respectively). 12.5 microg/mL of chromium chloride and 50 ng/mL of potassium dichromate were found to be optimal to discriminate between sensitized individuals with and without allergy. Combining the results of chromium chloride and potassium dichromate LTT, a positive reaction to at least one of the stimuli was highly predictive of allergy [sensitization with vs. without allergy: Odds ratio (OR)=6.4, P=0.004; sensitization with allergy vs. controls: OR=11.5, P&lt;0.0001]. On the contrary, IFN-gamma, IL-2, IL-4, IL-10, and IL-12 production to the ELISpot, patch test results, sensitization against other metals, and atopy score did not significantly discriminate between sensitization with and without allergy. However, IFN-gamma responses towards chromium chloride were significantly correlated with the strength of patch test reactivity (r=0.49, P=0.002). By IFN-gamma ELISpot, the average precursor cell frequency reactive to trivalent chromium could be defined as 26, 15, and 11 : 10(6) in volunteers with sensitization and allergy, with sensitization without allergy, and controls, respectively.<br /><br /><strong>CONCLUSIONS: </strong>In contrast to the patch test, the LTT appears to be a method that is predictive of chromium allergy."
1234213,Proskurnin and  Volkov 2008,Mode-mismatched dual-beam differential thermal lensing with optical scheme design optimized using expert estimation for analytical measurements,"The optimization of the optical scheme design of a mode-mismatched dual-beam thermal-lens spectrometer for differential (dual-cell) measurements in a far-field mode using diffraction thermal-lens theory is carried out. A criterion for an expert estimation of the quality of the spectrometer design for differential thermal-lens measurements in analytical chemistry (sensitivity, low limits of detection, and quantification) is also developed. The theoretical calculations agree well with previous papers on differential thermal lensing. Using the example of iron(II) tris-(1,10-phenanthrolinate), it is shown that the blank signal compensation in differential thermal lens spectrometry provides a decrease in the limit of detection by an order of magnitude compared to the decrease in single-cell measurements. Using an artificial two-component mixture of ferroin and potassium dichromate, it is shown that dual-beam differential thermal lens spectrometry makes it possible to determine trace components against 900-fold excess amounts of interfering substances.","Mode-mismatched dual-beam differential thermal lensing with optical scheme design optimized using expert estimation for analytical measurements Abs: The optimization of the optical scheme design of a mode-mismatched dual-beam thermal-lens spectrometer for differential (dual-cell) measurements in a far-field mode using diffraction thermal-lens theory is carried out. A criterion for an expert estimation of the quality of the spectrometer design for differential thermal-lens measurements in analytical chemistry (sensitivity, low limits of detection, and quantification) is also developed. The theoretical calculations agree well with previous papers on differential thermal lensing. Using the example of iron(II) tris-(1,10-phenanthrolinate), it is shown that the blank signal compensation in differential thermal lens spectrometry provides a decrease in the limit of detection by an order of magnitude compared to the decrease in single-cell measurements. Using an artificial two-component mixture of ferroin and potassium dichromate, it is shown that dual-beam differential thermal lens spectrometry makes it possible to determine trace components against 900-fold excess amounts of interfering substances."
1234211,Freise et al. 2008,Contact sensitization in patients with chronic wounds: results of a prospective investigation,"<strong>BACKGROUND: </strong>It is well known that patients with chronic wounds frequently acquire clinically relevant contact sensitizations to skin care products.<br /><br /><strong>OBJECTIVES: </strong>The aim of our study was to find out the actual frequency of contact sensitivities in patients with chronic wounds in Germany with particular attention to components of products used in modern wound therapy.<br /><br /><strong>METHODS: </strong>We examined the results of a prospective clinical investigation on skin patch tests of patients with chronic wounds.<br /><br /><strong>RESULTS: </strong>Altogether, 45 patients with chronic wounds were tested. In 25 (55.5%) of the examined patients, contact sensitization to at least one substance was detected. The most frequent contact sensitizations were to PVP-iodine (20%), balsam of Peru (15.6%) patients, fragrance mix (11.1%), colophony (8.8%) and potassium dichromate (6.7%). We also found sensitization to the wound dressings Varihesive (11.1%), Iruxol N (6.7%) and Comfeel (2.2%).<br /><br /><strong>CONCLUSIONS: </strong>We would like to propagate that therapists who are involved in wound treatment should also pay attention on the ingredients of applied modern wound dressings.","Contact sensitization in patients with chronic wounds: results of a prospective investigation Abs: <strong>BACKGROUND: </strong>It is well known that patients with chronic wounds frequently acquire clinically relevant contact sensitizations to skin care products.<br /><br /><strong>OBJECTIVES: </strong>The aim of our study was to find out the actual frequency of contact sensitivities in patients with chronic wounds in Germany with particular attention to components of products used in modern wound therapy.<br /><br /><strong>METHODS: </strong>We examined the results of a prospective clinical investigation on skin patch tests of patients with chronic wounds.<br /><br /><strong>RESULTS: </strong>Altogether, 45 patients with chronic wounds were tested. In 25 (55.5%) of the examined patients, contact sensitization to at least one substance was detected. The most frequent contact sensitizations were to PVP-iodine (20%), balsam of Peru (15.6%) patients, fragrance mix (11.1%), colophony (8.8%) and potassium dichromate (6.7%). We also found sensitization to the wound dressings Varihesive (11.1%), Iruxol N (6.7%) and Comfeel (2.2%).<br /><br /><strong>CONCLUSIONS: </strong>We would like to propagate that therapists who are involved in wound treatment should also pay attention on the ingredients of applied modern wound dressings."
1234210,Jappe et al. 2008,"Contact allergy in patients with rosacea: a clinic-based, prospective epidemiological study","<strong>BACKGROUND: </strong>Rosacea is a relatively common inflammatory skin disease of unknown prevalence. The proportion of contact allergy complicating rosacea and its therapy, respectively, is largely unknown.<br /><br /><strong>OBJECTIVE: </strong>To estimate the prevalence of specific contact allergy in rosacea patients and to compare this with the prevalence observed in the general population and in general patch test patients.<br /><br /><strong>PATIENTS/METHODS: </strong>In this prospective monocentre study, 78 patients with rosacea were investigated for contact sensitizations via patch testing the standard series, constituents of topical formulations, preservatives, fragrances, topically applied drugs and, if available, patient's own products.<br /><br /><strong>RESULTS: </strong>Positive reactions occurred to nickel (II) sulphate (12 of 78, 15.4%), fragrance mix I (4 of 77, 5.2%), balsam of Peru (8 of 77, 10.4%; significantly elevated prevalence compared to that observed in the population-based KORA study), potassium dichromate (4 of 78, 5.1%) and Lyral (3 of 78, 3.8%). Regarding topical antibiotics, only 1 of 78 (1.3%) patients was positive to neomycin sulphate, and none to metronidazole; however, 6 of 75 (8%) patients were positive to gentamicin sulphate, and 4 of 76 (5.3%) patients were positive to framycetin sulphate. No allergic but irritant patch test reactions, instead, were provoked by various patients' own products as well as by the irritant sodium lauryl sulphate (SLS) even in low concentrations.<br /><br /><strong>CONCLUSION: </strong>Despite the limited power of the study, a strikingly high prevalence of contact allergy to gentamicin sulphate was observed, which is probably due to antibiotic treatment of rosacea-associated eye symptoms. The reactions to the irritant SLS probably mirror the extreme skin sensitivity in rosacea.","Contact allergy in patients with rosacea: a clinic-based, prospective epidemiological study Abs: <strong>BACKGROUND: </strong>Rosacea is a relatively common inflammatory skin disease of unknown prevalence. The proportion of contact allergy complicating rosacea and its therapy, respectively, is largely unknown.<br /><br /><strong>OBJECTIVE: </strong>To estimate the prevalence of specific contact allergy in rosacea patients and to compare this with the prevalence observed in the general population and in general patch test patients.<br /><br /><strong>PATIENTS/METHODS: </strong>In this prospective monocentre study, 78 patients with rosacea were investigated for contact sensitizations via patch testing the standard series, constituents of topical formulations, preservatives, fragrances, topically applied drugs and, if available, patient's own products.<br /><br /><strong>RESULTS: </strong>Positive reactions occurred to nickel (II) sulphate (12 of 78, 15.4%), fragrance mix I (4 of 77, 5.2%), balsam of Peru (8 of 77, 10.4%; significantly elevated prevalence compared to that observed in the population-based KORA study), potassium dichromate (4 of 78, 5.1%) and Lyral (3 of 78, 3.8%). Regarding topical antibiotics, only 1 of 78 (1.3%) patients was positive to neomycin sulphate, and none to metronidazole; however, 6 of 75 (8%) patients were positive to gentamicin sulphate, and 4 of 76 (5.3%) patients were positive to framycetin sulphate. No allergic but irritant patch test reactions, instead, were provoked by various patients' own products as well as by the irritant sodium lauryl sulphate (SLS) even in low concentrations.<br /><br /><strong>CONCLUSION: </strong>Despite the limited power of the study, a strikingly high prevalence of contact allergy to gentamicin sulphate was observed, which is probably due to antibiotic treatment of rosacea-associated eye symptoms. The reactions to the irritant SLS probably mirror the extreme skin sensitivity in rosacea."
1234209,Elbekai and  El-Kadi 2008,"Arsenite and cadmium, but not chromium, induce NAD(P)H:quinone oxidoreductase 1 through transcriptional mechanisms, in spite of post-transcriptional modifications","NAD(P)H:quinone oxidoreductase (Nqo1)-mediated detoxification of quinones plays a critical role in cancer prevention. Metals alter the carcinogenicity of AhR ligands, such as TCDD, by modulating the induction of Nqo1, but the mechanism(s) remain unresolved. To decipher the molecular mechanisms involved in the alteration of Nqo1, we analyzed the effect of the metals As3+ (5 microM), Cd2+ (5 microM), and Cr6+ (25 microM) on the transcriptional activation of the Nqo1 gene and post-transcriptional modifications, in Hepa 1c1c7 cells. Both As3+ and Cd2+ induced Nqo1 mRNA in a time-dependent manner and potentiated TCDD-induced Nqo1 mRNA. Cr6+ on the other hand, completely inhibited the induction of Nqo1 mRNA by TCDD. The induction of Nqo1 mRNA by the metals was completely inhibited with the DNA transcription inhibitor actinomycin-D, indicating a requirement for de novo mRNA synthesis for the induction. Furthermore, the protein synthesis inhibitor cycloheximide decreased Nqo1 mRNA induction, suggesting a role for a labile protein in the transcriptional induction of Nqo1 mRNA by metals. Surprisingly, all three metals decreased Nqo1 mRNA stability while having no effect on Nqo1 protein half-life. Meanwhile, As3+ and Cd2+ induced constitutive Nqo1 activity and potentiated the induction by increasing concentrations of TCDD. On the other hand, Cr6+ inhibited inducible Nqo1 activity. It is apparent that metals alter Nqo1 expression at the transcriptional level, through a labile protein-mediated pathway.","Arsenite and cadmium, but not chromium, induce NAD(P)H:quinone oxidoreductase 1 through transcriptional mechanisms, in spite of post-transcriptional modifications Abs: NAD(P)H:quinone oxidoreductase (Nqo1)-mediated detoxification of quinones plays a critical role in cancer prevention. Metals alter the carcinogenicity of AhR ligands, such as TCDD, by modulating the induction of Nqo1, but the mechanism(s) remain unresolved. To decipher the molecular mechanisms involved in the alteration of Nqo1, we analyzed the effect of the metals As3+ (5 microM), Cd2+ (5 microM), and Cr6+ (25 microM) on the transcriptional activation of the Nqo1 gene and post-transcriptional modifications, in Hepa 1c1c7 cells. Both As3+ and Cd2+ induced Nqo1 mRNA in a time-dependent manner and potentiated TCDD-induced Nqo1 mRNA. Cr6+ on the other hand, completely inhibited the induction of Nqo1 mRNA by TCDD. The induction of Nqo1 mRNA by the metals was completely inhibited with the DNA transcription inhibitor actinomycin-D, indicating a requirement for de novo mRNA synthesis for the induction. Furthermore, the protein synthesis inhibitor cycloheximide decreased Nqo1 mRNA induction, suggesting a role for a labile protein in the transcriptional induction of Nqo1 mRNA by metals. Surprisingly, all three metals decreased Nqo1 mRNA stability while having no effect on Nqo1 protein half-life. Meanwhile, As3+ and Cd2+ induced constitutive Nqo1 activity and potentiated the induction by increasing concentrations of TCDD. On the other hand, Cr6+ inhibited inducible Nqo1 activity. It is apparent that metals alter Nqo1 expression at the transcriptional level, through a labile protein-mediated pathway."
1234208,Arivarasu et al. 2008,Oral administration of potassium dichromate inhibits brush border membrane enzymes and alters anti-oxidant status of rat intestine,"Potassium dichromate (K2Cr2O7) is a soluble hexavalent chromium compound that is widely used in several industries. In the present work the effect of administration of K2Cr2O7 on rat intestinal brush border membrane(BBM) enzymes and anti-oxidant system was studied. Rats were given a single oral dose of K2Cr2O7 (100 mg/kg bodyweight) and sacrificed 6, 12, 24, 48 and 96 h after the treatment.Control animals were not given K2Cr2O7. The administration of K2Cr2O7 resulted in a reversible decline in the specific activities of several BBM enzymes. The decrease in the activities of these enzymes was due to changes in the maximum velocity while their affinities for the substrates remained unchanged. Lipid peroxidation increased while total SH groups decreased in K2Cr2O7-treated rats as compared to controls indicating increased oxidative stress in the intestinal mucosa. The activities of superoxide dismutase and glutathione-S-transferase increased while those of catalase, glutathione reductase, thioredoxin reductase and glucose-6-phosphate dehydrogenase decreased. The maximum changes in all the parameters studied above were 24 h after administration of K2Cr2O7 after which recovery took place,in most cases almost to control values after 96 h. These results show that oral administration of K2Cr2O7 to decrease in the activities of BBM enzymes, increase in oxidative stress and alters the activities of anti-oxidant enzymes in rat intestine.","Oral administration of potassium dichromate inhibits brush border membrane enzymes and alters anti-oxidant status of rat intestine Abs: Potassium dichromate (K2Cr2O7) is a soluble hexavalent chromium compound that is widely used in several industries. In the present work the effect of administration of K2Cr2O7 on rat intestinal brush border membrane(BBM) enzymes and anti-oxidant system was studied. Rats were given a single oral dose of K2Cr2O7 (100 mg/kg bodyweight) and sacrificed 6, 12, 24, 48 and 96 h after the treatment.Control animals were not given K2Cr2O7. The administration of K2Cr2O7 resulted in a reversible decline in the specific activities of several BBM enzymes. The decrease in the activities of these enzymes was due to changes in the maximum velocity while their affinities for the substrates remained unchanged. Lipid peroxidation increased while total SH groups decreased in K2Cr2O7-treated rats as compared to controls indicating increased oxidative stress in the intestinal mucosa. The activities of superoxide dismutase and glutathione-S-transferase increased while those of catalase, glutathione reductase, thioredoxin reductase and glucose-6-phosphate dehydrogenase decreased. The maximum changes in all the parameters studied above were 24 h after administration of K2Cr2O7 after which recovery took place,in most cases almost to control values after 96 h. These results show that oral administration of K2Cr2O7 to decrease in the activities of BBM enzymes, increase in oxidative stress and alters the activities of anti-oxidant enzymes in rat intestine."
1234206,Ikuno et al. 2008,Difference in the sensitivity to chemical compounds between female and male neonates of Daphnia magna,"Daphnia magna usually produce female offspring by parthenogenesis, and thus only female neonates are used to evaluate the environmental toxicity to chemicals. Additionally, it is known that male daphnids are induced by exposure to a juvenile hormone, methyl farnesoate, during late ovarian development. In this study, we investigated the concentration of methyl farnesoate in a 24-h exposure producing 100% males, and the difference in sensitivity to chemical compounds, potassium dichromate, pentachlorophenol, and paraquat, between females and males, referring to OECD Test Guideline 202. The results show that the minimum concentration for 100%-male induction of methyl farnesoate in adult females was 50 microg/L. In addition, acute toxicity tests (immobility test) with the other chemicals showed that male neonates have higher tolerance to potassium dichromate and pentachlorophenol than females for at least 24 h after birth, while no sex difference was observed in the sensitivity to paraquat. The differences in the median effective concentrations in these compounds between female and male neonates suggest two different overall modes of action. Using female daphnids for environmentally toxicity testing seems reasonable, since the females are more sensitive to chemicals than males. Furthermore, the method of male induction established in this study could be used for screening of endocrine disruptors.","Difference in the sensitivity to chemical compounds between female and male neonates of Daphnia magna Abs: Daphnia magna usually produce female offspring by parthenogenesis, and thus only female neonates are used to evaluate the environmental toxicity to chemicals. Additionally, it is known that male daphnids are induced by exposure to a juvenile hormone, methyl farnesoate, during late ovarian development. In this study, we investigated the concentration of methyl farnesoate in a 24-h exposure producing 100% males, and the difference in sensitivity to chemical compounds, potassium dichromate, pentachlorophenol, and paraquat, between females and males, referring to OECD Test Guideline 202. The results show that the minimum concentration for 100%-male induction of methyl farnesoate in adult females was 50 microg/L. In addition, acute toxicity tests (immobility test) with the other chemicals showed that male neonates have higher tolerance to potassium dichromate and pentachlorophenol than females for at least 24 h after birth, while no sex difference was observed in the sensitivity to paraquat. The differences in the median effective concentrations in these compounds between female and male neonates suggest two different overall modes of action. Using female daphnids for environmentally toxicity testing seems reasonable, since the females are more sensitive to chemicals than males. Furthermore, the method of male induction established in this study could be used for screening of endocrine disruptors."
1234205,Kappen et al. 2008,Time-resolved XANES speciation studies of chromium on soils during simulated contamination,"Time-resolved synchrotron X-ray absorption near edge structure (XANES) spectroscopy was used to study changes of chromium speciation in soils upon soil-water interaction. The time resolution was 30-45 min. In a flow-column apparatus operated near the synchrotron beamline, two different types of soil were treated with potassium-dichromate solution, and soil samples were taken and directly analysed by XANES. The results provide insight into different equilibrium times of a few hours, depending on the type of soil. The XANES speciation analyses, based on a model comprising insoluble Cr(III) and Cr(VI) compounds, show how the fate of Cr species on soils can be followed close to real-time. Since the method allowed the soils to be investigated close to real-time, sampling in the field and preservation before analysis were made redundant. This study benefits the development of corresponding in situ remediation techniques.","Time-resolved XANES speciation studies of chromium on soils during simulated contamination Abs: Time-resolved synchrotron X-ray absorption near edge structure (XANES) spectroscopy was used to study changes of chromium speciation in soils upon soil-water interaction. The time resolution was 30-45 min. In a flow-column apparatus operated near the synchrotron beamline, two different types of soil were treated with potassium-dichromate solution, and soil samples were taken and directly analysed by XANES. The results provide insight into different equilibrium times of a few hours, depending on the type of soil. The XANES speciation analyses, based on a model comprising insoluble Cr(III) and Cr(VI) compounds, show how the fate of Cr species on soils can be followed close to real-time. Since the method allowed the soils to be investigated close to real-time, sampling in the field and preservation before analysis were made redundant. This study benefits the development of corresponding in situ remediation techniques."
1234204,Comet et al. 2008,Preparation of explosive nanoparticles in a porous chromium(III) oxide matrix: a first attempt to control the reactivity of explosives,"This paper reports the first attempt to control the combustion and the detonation properties of a high explosive through its structure. A porous chromium(III) oxide matrix produced by the combustion of ammonium dichromate was infiltrated by hexahydro-1,3,5-trinitro-1,3,5-triazine (RDX). The structure of the Cr(2)O(3) matrix was studied by both scanning and transmission electron microscopy (SEM, TEM); the Cr(2)O(3)/RDX nanocomposites were characterized by nitrogen adsorption. A mathematical model based on these techniques was used to demonstrate that the Cr(2)O(3) matrix encloses and stabilizes RDX particles at the nanoscale. The decomposition process of the nanocomposites was investigated by atomic force microscopy (AFM). The reactivity and sensitivity of the nanocomposites were studied by impact and friction tests, differential scanning calorimetry (DSC), time-resolved cinematography and detonation experiments, and were correlated with their structure. The size of RDX nanoparticles and their distribution in the Cr(2)O(3) matrix have an important influence on their reactivity. The reactive properties of nanostructured RDX differ significantly from those of classical micron-sized RDX. For instance, the melting point disappears and the decomposition temperature is significantly lowered. The quantization of the explosive particles in the Cr(2)O(3) matrix decreases the sensitivity to mechanical stress and allows controlling the decomposition mode-i.e. combustion versus detonation.","Preparation of explosive nanoparticles in a porous chromium(III) oxide matrix: a first attempt to control the reactivity of explosives Abs: This paper reports the first attempt to control the combustion and the detonation properties of a high explosive through its structure. A porous chromium(III) oxide matrix produced by the combustion of ammonium dichromate was infiltrated by hexahydro-1,3,5-trinitro-1,3,5-triazine (RDX). The structure of the Cr(2)O(3) matrix was studied by both scanning and transmission electron microscopy (SEM, TEM); the Cr(2)O(3)/RDX nanocomposites were characterized by nitrogen adsorption. A mathematical model based on these techniques was used to demonstrate that the Cr(2)O(3) matrix encloses and stabilizes RDX particles at the nanoscale. The decomposition process of the nanocomposites was investigated by atomic force microscopy (AFM). The reactivity and sensitivity of the nanocomposites were studied by impact and friction tests, differential scanning calorimetry (DSC), time-resolved cinematography and detonation experiments, and were correlated with their structure. The size of RDX nanoparticles and their distribution in the Cr(2)O(3) matrix have an important influence on their reactivity. The reactive properties of nanostructured RDX differ significantly from those of classical micron-sized RDX. For instance, the melting point disappears and the decomposition temperature is significantly lowered. The quantization of the explosive particles in the Cr(2)O(3) matrix decreases the sensitivity to mechanical stress and allows controlling the decomposition mode-i.e. combustion versus detonation."
1234203,Boonchai et al. 2008,Prevalence of allergic contact dermatitis in Thailand,"<strong>BACKGROUND: </strong>Contact dermatitis is a universal condition. Patch testing is an effective diagnostic tool for clinically suspected allergic contact dermatitis. Previous studies have shown that the prevalence of specific allergens varies by geographic area.<br /><br /><strong>OBJECTIVE: </strong>To determine the relative frequency of positive reactions to different sensitizers in Thai patients with clinically suspected contact dermatitis.<br /><br /><strong>METHODS: </strong>The results of patch tests performed from January 1, 2004, to December 31, 2006, at the Siriraj Hospital Contact Dermatitis Clinic were analyzed. A total of 323 consecutive patients (83% women and 17% men, with mean age of 39 years) were patch-tested with the total number of allergens used from both European standard patch test series and International patch test series was 26.<br /><br /><strong>RESULTS: </strong>The most frequent allergen was potassium dichromate (27%), followed by nickel sulfate (26.6%), fragrance mix (20.7%), and cobalt chloride (16.4%).<br /><br /><strong>CONCLUSIONS: </strong>We compared the results with published findings in Asian-Pacific populations to identify geographic cultural differences in the prevalence of the allergens. The findings of the present study are able to identify the set of prominent local allergens for better revision of the standard patch test to local needs.","Prevalence of allergic contact dermatitis in Thailand Abs: <strong>BACKGROUND: </strong>Contact dermatitis is a universal condition. Patch testing is an effective diagnostic tool for clinically suspected allergic contact dermatitis. Previous studies have shown that the prevalence of specific allergens varies by geographic area.<br /><br /><strong>OBJECTIVE: </strong>To determine the relative frequency of positive reactions to different sensitizers in Thai patients with clinically suspected contact dermatitis.<br /><br /><strong>METHODS: </strong>The results of patch tests performed from January 1, 2004, to December 31, 2006, at the Siriraj Hospital Contact Dermatitis Clinic were analyzed. A total of 323 consecutive patients (83% women and 17% men, with mean age of 39 years) were patch-tested with the total number of allergens used from both European standard patch test series and International patch test series was 26.<br /><br /><strong>RESULTS: </strong>The most frequent allergen was potassium dichromate (27%), followed by nickel sulfate (26.6%), fragrance mix (20.7%), and cobalt chloride (16.4%).<br /><br /><strong>CONCLUSIONS: </strong>We compared the results with published findings in Asian-Pacific populations to identify geographic cultural differences in the prevalence of the allergens. The findings of the present study are able to identify the set of prominent local allergens for better revision of the standard patch test to local needs."
1234202,Traidl-Hoffmann and  Ring 2008,Is there an in vitro test for type IV allergy discriminating between sensitization and allergic disease?,,Is there an in vitro test for type IV allergy discriminating between sensitization and allergic disease? Abs: 
1234201,Castanedo-Tardan and  Jacob 2008,Potassium dichromate,,Potassium dichromate Abs: 
1234198,Friedmann and  Goldsmith 2008,Tefillin contact dermatitis: a problem in the devout,,Tefillin contact dermatitis: a problem in the devout Abs: 
1234197,Glaviano et al. 2009,Effects of hTERT on genomic instability caused by either metal or radiation or combined exposure,"Genomic instability is considered to be an important component in carcinogenesis. It can be caused by low-dose exposure to agents, which appear to act through induction of stress-response pathways related to oxidative stress. These agents have been studied mostly in the radiation field but evidence is accumulating that chemicals, especially heavy metals such as Cr (VI), can also act in the same manner. Previous work showed that metal ions could initiate long-term genomic instability in human primary fibroblasts and this phenomenon was regulated by telomerase. The aim of this study was to examine the difference in clonogenic survival and cytogenetic damage after exposure to Cr (VI) and radiation both singly and in combination in normal human fibroblasts (hTERT- cells) and engineered human fibroblasts, infected with a retrovirus carrying a cDNA encoding hTERT, which rendered these cells telomerase positive and replicatively immortal (hTERT+ cells). Cr (VI) induced genomic instability in hTERT- cells but not in hTERT+ cells, whereas radiation induced genomic instability in hTERT+ cells and to a lesser extent in hTERT- cells. Combined exposure caused genomic instability in both types of cells. However, this genomic instability was more pronounced in hTERT- cells after radiation followed by Cr (VI) and more pronounced in hTERT+ cells after Cr (VI) followed by radiation. Moreover, the biological effects provoked by combined exposure of Cr (VI) and radiation also led to a synergistic action in both types of cells, compared to either Cr (VI) treatment only or radiation exposure only. This study suggests that telomerase can prevent genomic instability caused by Cr (VI), but not by radiation. Furthermore, genomic instability may be prevented by telomerase when cells are exposed to radiation and then Cr (VI) but not after exposure to Cr (VI) and then radiation.","Effects of hTERT on genomic instability caused by either metal or radiation or combined exposure Abs: Genomic instability is considered to be an important component in carcinogenesis. It can be caused by low-dose exposure to agents, which appear to act through induction of stress-response pathways related to oxidative stress. These agents have been studied mostly in the radiation field but evidence is accumulating that chemicals, especially heavy metals such as Cr (VI), can also act in the same manner. Previous work showed that metal ions could initiate long-term genomic instability in human primary fibroblasts and this phenomenon was regulated by telomerase. The aim of this study was to examine the difference in clonogenic survival and cytogenetic damage after exposure to Cr (VI) and radiation both singly and in combination in normal human fibroblasts (hTERT- cells) and engineered human fibroblasts, infected with a retrovirus carrying a cDNA encoding hTERT, which rendered these cells telomerase positive and replicatively immortal (hTERT+ cells). Cr (VI) induced genomic instability in hTERT- cells but not in hTERT+ cells, whereas radiation induced genomic instability in hTERT+ cells and to a lesser extent in hTERT- cells. Combined exposure caused genomic instability in both types of cells. However, this genomic instability was more pronounced in hTERT- cells after radiation followed by Cr (VI) and more pronounced in hTERT+ cells after Cr (VI) followed by radiation. Moreover, the biological effects provoked by combined exposure of Cr (VI) and radiation also led to a synergistic action in both types of cells, compared to either Cr (VI) treatment only or radiation exposure only. This study suggests that telomerase can prevent genomic instability caused by Cr (VI), but not by radiation. Furthermore, genomic instability may be prevented by telomerase when cells are exposed to radiation and then Cr (VI) but not after exposure to Cr (VI) and then radiation."
1234196,Palma et al. 2008,"Acute toxicity of atrazine, endosulfan sulphate and chlorpyrifos to Vibrio fischeri, Thamnocephalus platyurus and Daphnia magna, relative to their concentrations in surface waters from the Alentejo region of Portugal","Ecotoxicological effects of the herbicide atrazine and the insecticides endosulfan sulphate and chlorpyrifos were evaluated using a test battery comprising aquatic organisms from different trophic levels. According to the categories established in the EU legislation, atrazine can be considered non-harmful for the species tested, while the insecticides can be considered very toxic for the crustaceans. The results of acute toxicity tests showed that the sensitivity of organisms were as follows: Thamnocephalus platyurus &gt; Daphnia magna &gt; Vibrio fischeri. Chlorpyrifos may act as a toxic compound in the aquatic environment of Guadiana River, as it may be detected in water at levels that promote toxic effects.","Acute toxicity of atrazine, endosulfan sulphate and chlorpyrifos to Vibrio fischeri, Thamnocephalus platyurus and Daphnia magna, relative to their concentrations in surface waters from the Alentejo region of Portugal Abs: Ecotoxicological effects of the herbicide atrazine and the insecticides endosulfan sulphate and chlorpyrifos were evaluated using a test battery comprising aquatic organisms from different trophic levels. According to the categories established in the EU legislation, atrazine can be considered non-harmful for the species tested, while the insecticides can be considered very toxic for the crustaceans. The results of acute toxicity tests showed that the sensitivity of organisms were as follows: Thamnocephalus platyurus &gt; Daphnia magna &gt; Vibrio fischeri. Chlorpyrifos may act as a toxic compound in the aquatic environment of Guadiana River, as it may be detected in water at levels that promote toxic effects."
1234194,Chiusolo et al. 2008,Regucalcin down-regulation in rat kidney tissue after treatment with nephrotoxicants,"Gene expression of regucalcin (Rgn), a calcium-binding protein, was investigated in kidney of male Wistar rats treated with proximal tubule segment-specific nephrotoxicants, namely hexachloro-1:3-butadiene (HCBD), specific for S(3) segment (pars recta) and potassium dichromate (chromate) specific for S(1)-S(2) segments (pars convoluta), according to age of animals and dose of chemicals. In the age-dependent study, male Wistar rats were treated with a single injection of HCBD (100mg/kg b.w. i.p.) or chromate (25 mg/kg b.w. s.c.) at 5 weeks or 12 weeks of age; in dose-response study, rats were treated with a single injection of three doses of HCBD (25, 50, and 100 mg/kg b.w. i.p.) or chromate (8, 12.5, and 25mg/kg b.w. s.c.) at 8 weeks of age. Forty-eight hours after treatment, Rgn and glutamine synthetase (GS) activity in kidney cortex, blood urea nitrogen (BUN) and plasma creatinine were measured; light microscopy was performed also. The results show that young rats are less susceptible to chromate (severe necrosis is evident only in adult rats), whereas age does not influence HCBD nephrotoxicity. Rgn is down regulated by HCBD at both age points, but not by chromate at 5 weeks of age. In addition, HCBD causes down-regulation of Rgn from the low dose in 8-week-old rats, whereas chromate causes the same effect at the high dose only. GS activity in kidney cortex shows a similar behavior, even if sensitive to low doses of chromate also, whereas BUN and creatinine increase after the high dose of both chemicals only. Accordingly, light microscopy shows a segment-specific, dose-dependent increase of severity of damage caused by the chemicals. Rgn gene expression appears a sensitive genomic marker to evaluate the renal impairment caused by chemicals and its down-regulation seems to be related to damage, early or already established, to S(3) segment of the proximal tubule.","Regucalcin down-regulation in rat kidney tissue after treatment with nephrotoxicants Abs: Gene expression of regucalcin (Rgn), a calcium-binding protein, was investigated in kidney of male Wistar rats treated with proximal tubule segment-specific nephrotoxicants, namely hexachloro-1:3-butadiene (HCBD), specific for S(3) segment (pars recta) and potassium dichromate (chromate) specific for S(1)-S(2) segments (pars convoluta), according to age of animals and dose of chemicals. In the age-dependent study, male Wistar rats were treated with a single injection of HCBD (100mg/kg b.w. i.p.) or chromate (25 mg/kg b.w. s.c.) at 5 weeks or 12 weeks of age; in dose-response study, rats were treated with a single injection of three doses of HCBD (25, 50, and 100 mg/kg b.w. i.p.) or chromate (8, 12.5, and 25mg/kg b.w. s.c.) at 8 weeks of age. Forty-eight hours after treatment, Rgn and glutamine synthetase (GS) activity in kidney cortex, blood urea nitrogen (BUN) and plasma creatinine were measured; light microscopy was performed also. The results show that young rats are less susceptible to chromate (severe necrosis is evident only in adult rats), whereas age does not influence HCBD nephrotoxicity. Rgn is down regulated by HCBD at both age points, but not by chromate at 5 weeks of age. In addition, HCBD causes down-regulation of Rgn from the low dose in 8-week-old rats, whereas chromate causes the same effect at the high dose only. GS activity in kidney cortex shows a similar behavior, even if sensitive to low doses of chromate also, whereas BUN and creatinine increase after the high dose of both chemicals only. Accordingly, light microscopy shows a segment-specific, dose-dependent increase of severity of damage caused by the chemicals. Rgn gene expression appears a sensitive genomic marker to evaluate the renal impairment caused by chemicals and its down-regulation seems to be related to damage, early or already established, to S(3) segment of the proximal tubule."
1234192,Jacob et al. 2008,Inflammation in green (chromium) tattoos during patch testing,"We report three patients with permanent tattoos and chronic dermatitis. During patch testing, the patients' dermatitis worsened, and the previously quiescent green-colored portions of the tattoos became inflamed. All three patients were patch-tested and had positive reactions to potassium dichromate 0.25% in petrolatum. Avoidance led to the resolution of both the dermatitis and the tattoo inflammation. We recommend assessment of permanent tattoos for inflammation in all patients undergoing patch testing, for additional diagnostic correlation.","Inflammation in green (chromium) tattoos during patch testing Abs: We report three patients with permanent tattoos and chronic dermatitis. During patch testing, the patients' dermatitis worsened, and the previously quiescent green-colored portions of the tattoos became inflamed. All three patients were patch-tested and had positive reactions to potassium dichromate 0.25% in petrolatum. Avoidance led to the resolution of both the dermatitis and the tattoo inflammation. We recommend assessment of permanent tattoos for inflammation in all patients undergoing patch testing, for additional diagnostic correlation."
1234190,Cohen et al. 2006,Pulmonary immunotoxic potentials of metals are governed by select physicochemical properties: chromium agents,"Increasing the understanding of how metal ions/complexes react in situ will allow for the improved specificity and controlled toxicity of novel synthetic metallocompounds that will be used as inhaled diagnostics or therapeutics. Our previous work showed that inhalation of select metals (e.g., chromium, vanadium, nickel, iron) caused alterations in lung immune cell function and in local bacterial resistance. The data also suggested that variations in the degree of immuno-modulation induced were not solely dependent on the amount of metal deposited in the lung, but also on the specific compound. If specificity governs immunomodulatory potential, it follows that physicochemical properties inherent to the metal may have a role in the elicited effects. We hypothesize that major determinants of any metal compound's immunomodulatory potential in situ are its redox behavior, valency, and/or solubility. Using changes in local bacterial resistance as an endpoint, differences in immunotoxic potential in the lungs were quantified for a range of chromium agents (insoluble calcium chromate(VI), and soluble sodium chromate(VI), potassium bis(dipicolinato)chromate(III) and sodium bis(dipicolinato)chromate(II)). Results indicated that among the latter three forms of Cr, strongly oxidizing hexavalent Cr (Cr[VI]) had the greatest impact on resistance, while reducing divalent and fairly unreactive trivalent forms of Cr had no effect at an equal exposure level (i.e., 100 microg Cr/m(3), 5 hr/d, for 5 d). Insoluble Cr(VI) had a greater effect than its soluble form. When data was analyzed in the context of pre-infection lung Cr burdens, it was seen that immunomodulatory potentials for both Cr(VI) agents did not differ significantly; however, complexes with different oxidation states did induce varying responses, suggesting that differences in potential might be attributed to redox behavior. From this it was concluded that for Cr, certain physicochemical properties are likely more important to any in situ pulmonary immunotoxicity than others (i.e., redox behavior is more critical than solubility). Our findings, in part, will help provide a basis for understanding why certain metals could be a greater health risk than others, even when encountered in equal amounts. This, in turn, will help researchers in the design of inhalable diagnostic/therapeutic metallopharmaceuticals by pre-empting the selection of certain metal ions/complexes for potential use in these products.","Pulmonary immunotoxic potentials of metals are governed by select physicochemical properties: chromium agents Abs: Increasing the understanding of how metal ions/complexes react in situ will allow for the improved specificity and controlled toxicity of novel synthetic metallocompounds that will be used as inhaled diagnostics or therapeutics. Our previous work showed that inhalation of select metals (e.g., chromium, vanadium, nickel, iron) caused alterations in lung immune cell function and in local bacterial resistance. The data also suggested that variations in the degree of immuno-modulation induced were not solely dependent on the amount of metal deposited in the lung, but also on the specific compound. If specificity governs immunomodulatory potential, it follows that physicochemical properties inherent to the metal may have a role in the elicited effects. We hypothesize that major determinants of any metal compound's immunomodulatory potential in situ are its redox behavior, valency, and/or solubility. Using changes in local bacterial resistance as an endpoint, differences in immunotoxic potential in the lungs were quantified for a range of chromium agents (insoluble calcium chromate(VI), and soluble sodium chromate(VI), potassium bis(dipicolinato)chromate(III) and sodium bis(dipicolinato)chromate(II)). Results indicated that among the latter three forms of Cr, strongly oxidizing hexavalent Cr (Cr[VI]) had the greatest impact on resistance, while reducing divalent and fairly unreactive trivalent forms of Cr had no effect at an equal exposure level (i.e., 100 microg Cr/m(3), 5 hr/d, for 5 d). Insoluble Cr(VI) had a greater effect than its soluble form. When data was analyzed in the context of pre-infection lung Cr burdens, it was seen that immunomodulatory potentials for both Cr(VI) agents did not differ significantly; however, complexes with different oxidation states did induce varying responses, suggesting that differences in potential might be attributed to redox behavior. From this it was concluded that for Cr, certain physicochemical properties are likely more important to any in situ pulmonary immunotoxicity than others (i.e., redox behavior is more critical than solubility). Our findings, in part, will help provide a basis for understanding why certain metals could be a greater health risk than others, even when encountered in equal amounts. This, in turn, will help researchers in the design of inhalable diagnostic/therapeutic metallopharmaceuticals by pre-empting the selection of certain metal ions/complexes for potential use in these products."
1234188,Gros 2004,Spectrometer with microreaction chamber and tri-colour light emitting diode as a light source,"This paper describes a tri-colour light emitting diode (LED)-photoresistor (PR)-based in situ spectrometer with geometry that differs from the previously presented and allows for small volumes of test solution (350mul) and effective homogenisation of reagents. The emission maximums of the tri-colour LED (TC-LED) are at 470, 565 and 660nm. The basic measuring characteristics of the prototype were evaluated. The prototype was tested for determination of calcium in natural waters with the o-cresolphtalein complexon and was proved to be useful for real life applications. The in situ spectrometer with microreaction chamber enables the rapid optimisation of experimental conditions, as was demonstrated on the example of oxidation of alcohols with potassium dichromate. The drop-based experimental approach to the ruggedness test is fast, economic and gives reliable results with the minimum waste production. The prototype, connected to the computer, functions as a kinetic microreactor suitable also for following rapid changes. In spite of the manual addition of the initialising reagent, the data are lost only during the first 3s.","Spectrometer with microreaction chamber and tri-colour light emitting diode as a light source Abs: This paper describes a tri-colour light emitting diode (LED)-photoresistor (PR)-based in situ spectrometer with geometry that differs from the previously presented and allows for small volumes of test solution (350mul) and effective homogenisation of reagents. The emission maximums of the tri-colour LED (TC-LED) are at 470, 565 and 660nm. The basic measuring characteristics of the prototype were evaluated. The prototype was tested for determination of calcium in natural waters with the o-cresolphtalein complexon and was proved to be useful for real life applications. The in situ spectrometer with microreaction chamber enables the rapid optimisation of experimental conditions, as was demonstrated on the example of oxidation of alcohols with potassium dichromate. The drop-based experimental approach to the ruggedness test is fast, economic and gives reliable results with the minimum waste production. The prototype, connected to the computer, functions as a kinetic microreactor suitable also for following rapid changes. In spite of the manual addition of the initialising reagent, the data are lost only during the first 3s."
1234187,Fan et al. 2005,Non-equilibrium determination of metoclopramide and tetracaine hydrochloride by sequential injection spectrophotometry,"A new sequential injection spectrophotometric method was proposed for the determination of metoclopramide and tetracaine hydrochloride. The method was based on the detection of an unstable red intermediate compound resulting from the reaction of metoclopramide or tetracaine hydrochloride with potassium dichromate, in the presence of sodium oxalate, in sulfuric acid solution. The related reaction mechanisms of this new method have been studied. The experimental conditions were optimized for the stopped-flow and continuous-flow sequential injection models. For continuous flow, the linear range for determination of metoclopramide, the detection limit and the sampling frequency were 13-130 microgml(-1), 9.4 microgml(-1) and 40 samples per hour, respectively. For stopped flow, they were 3-42 microgml(-1), 1.0 microgml(-1) and 18h(-1), respectively. Adopting the continuous-flow model for tetracaine hydrochloride, the linear range was 25-300 microgml(-1), and the detection limit was 18.0 microgml(-1) with sampling frequency of 40h(-1). This method has been used to determine metoclopramide and tetracaine hydrochloride in pharmaceutical preparations, and the results are compared with those determined by the pharmacopoeia method. Statistical analysis reveals that there was no evidence of significant difference between the methods.","Non-equilibrium determination of metoclopramide and tetracaine hydrochloride by sequential injection spectrophotometry Abs: A new sequential injection spectrophotometric method was proposed for the determination of metoclopramide and tetracaine hydrochloride. The method was based on the detection of an unstable red intermediate compound resulting from the reaction of metoclopramide or tetracaine hydrochloride with potassium dichromate, in the presence of sodium oxalate, in sulfuric acid solution. The related reaction mechanisms of this new method have been studied. The experimental conditions were optimized for the stopped-flow and continuous-flow sequential injection models. For continuous flow, the linear range for determination of metoclopramide, the detection limit and the sampling frequency were 13-130 microgml(-1), 9.4 microgml(-1) and 40 samples per hour, respectively. For stopped flow, they were 3-42 microgml(-1), 1.0 microgml(-1) and 18h(-1), respectively. Adopting the continuous-flow model for tetracaine hydrochloride, the linear range was 25-300 microgml(-1), and the detection limit was 18.0 microgml(-1) with sampling frequency of 40h(-1). This method has been used to determine metoclopramide and tetracaine hydrochloride in pharmaceutical preparations, and the results are compared with those determined by the pharmacopoeia method. Statistical analysis reveals that there was no evidence of significant difference between the methods."
1234186,Seo et al. 2009,Measurement of ethanol concentration using solvent extraction and dichromate oxidation and its application to bioethanol production process,"A method for measuring the ethanol concentration in a yeast culture broth was developed using both microtubes and a 96-deepwell microplate. The strategy involved first the solvent extraction of ethanol from the yeast culture broth and measurements of the ethanol concentration using the dichromate oxidation method. Particular focus was made on selecting the extraction solvent as well as determining the measurable range of ethanol concentrations using this solvent extraction-dichromate oxidation method. This method was developed as an assay format in 2.0-ml microtubes and 1.2-ml 96-deepwell microplates, and the ethanol concentration in the batch cultures and fed-batch fermentations was measured. Tri-n-butyl phosphate [non-alcoholic solvent, density = 0.9727, solubility in water = 0.028% (w/v)] was used for solvent extraction when measuring the ethanol concentration from the yeast culture broth. The maximum detectable ethanol concentration was 8% (v/v) when 10 g potassium dichromate in 100 ml of 5 M sulfuric acid was used. The concentrations determined from the solvent extraction-dichromate oxidation methods were remarkably similar to those of gas chromatography in which samples were prepared from seven experiments, such as four batch cultures and three fed-batch fermentations.","Measurement of ethanol concentration using solvent extraction and dichromate oxidation and its application to bioethanol production process Abs: A method for measuring the ethanol concentration in a yeast culture broth was developed using both microtubes and a 96-deepwell microplate. The strategy involved first the solvent extraction of ethanol from the yeast culture broth and measurements of the ethanol concentration using the dichromate oxidation method. Particular focus was made on selecting the extraction solvent as well as determining the measurable range of ethanol concentrations using this solvent extraction-dichromate oxidation method. This method was developed as an assay format in 2.0-ml microtubes and 1.2-ml 96-deepwell microplates, and the ethanol concentration in the batch cultures and fed-batch fermentations was measured. Tri-n-butyl phosphate [non-alcoholic solvent, density = 0.9727, solubility in water = 0.028% (w/v)] was used for solvent extraction when measuring the ethanol concentration from the yeast culture broth. The maximum detectable ethanol concentration was 8% (v/v) when 10 g potassium dichromate in 100 ml of 5 M sulfuric acid was used. The concentrations determined from the solvent extraction-dichromate oxidation methods were remarkably similar to those of gas chromatography in which samples were prepared from seven experiments, such as four batch cultures and three fed-batch fermentations."
1234185,Schecter et al. 2009,Limitations in the use of potassium dichromate as a blood preservative for the analysis of organohalogenated compounds: two month results,"For analysis of organochlorine contaminants in human tissue, the &quot;gold standard&quot; for preservation, storage, and shipping is usually freezing. However, this method can be difficult, if samples are taken in remote areas, and costly, when the samples must be shipped on dry ice. Therefore, a more simple and cost effective method of preservation is essential for remote field work. Potassium dichromate (K(2)Cr(2)O(7)) has been successfully employed in the preservation of human and cows' milk as well as chicken eggs. Our previous studies described the use of potassium dichromate for preservation of whole blood for analysis of dioxins, dibenzofurans, and PCBs. Potassium dichromate was found to successfully preserve blood at room temperature for 34 d with no significant differences in the measured concentrations of chemical contaminants or blood lipid level when compared to frozen samples. However, in a follow-up study, 3 months and 6 months of potassium dichromate preservation proved inadequate to preserve the samples for organic pollutant analysis. We noted that the lipid portion of the blood in the chemically preserved samples was declining in level or degrading, while the persistent organic pollutants remained intact at the same levels on a whole weight basis. To narrow down the window of efficacy for the use of potassium dichromate to preserve blood samples for analysis, the present study compared chemical preservation to freezing for an intermediate time period, 2 months. Similar to our previous findings at 3 and 6 months, at 2 months significant lipid degradation was observed in the chemically preserved samples. Chemically preserved samples had significantly higher levels of organochlorine contaminants (dioxins, dibenzofurans, and PCBs) when measured on a blood lipid basis but not on a wet weight basis compared to frozen samples. While 2 months of potassium dichromate preservation was not useful for obtaining accurate measure of dioxins, furans, and PCBs on a lipid basis, previous studies found this method of preservation to be useful for at least one month (Schecter, A., Pavuk, M., Päpke, O., Malisch, R., 2004. The use of potassium dichromate and ethyl alcohol as blood preservatives for analysis of organochlorine contaminants. Chemosphere 57, 1-7). However blood stored at -70 degrees C and at 22 degrees C with potassium dichromate gave similar results when expressed on a wet weight basis.","Limitations in the use of potassium dichromate as a blood preservative for the analysis of organohalogenated compounds: two month results Abs: For analysis of organochlorine contaminants in human tissue, the &quot;gold standard&quot; for preservation, storage, and shipping is usually freezing. However, this method can be difficult, if samples are taken in remote areas, and costly, when the samples must be shipped on dry ice. Therefore, a more simple and cost effective method of preservation is essential for remote field work. Potassium dichromate (K(2)Cr(2)O(7)) has been successfully employed in the preservation of human and cows' milk as well as chicken eggs. Our previous studies described the use of potassium dichromate for preservation of whole blood for analysis of dioxins, dibenzofurans, and PCBs. Potassium dichromate was found to successfully preserve blood at room temperature for 34 d with no significant differences in the measured concentrations of chemical contaminants or blood lipid level when compared to frozen samples. However, in a follow-up study, 3 months and 6 months of potassium dichromate preservation proved inadequate to preserve the samples for organic pollutant analysis. We noted that the lipid portion of the blood in the chemically preserved samples was declining in level or degrading, while the persistent organic pollutants remained intact at the same levels on a whole weight basis. To narrow down the window of efficacy for the use of potassium dichromate to preserve blood samples for analysis, the present study compared chemical preservation to freezing for an intermediate time period, 2 months. Similar to our previous findings at 3 and 6 months, at 2 months significant lipid degradation was observed in the chemically preserved samples. Chemically preserved samples had significantly higher levels of organochlorine contaminants (dioxins, dibenzofurans, and PCBs) when measured on a blood lipid basis but not on a wet weight basis compared to frozen samples. While 2 months of potassium dichromate preservation was not useful for obtaining accurate measure of dioxins, furans, and PCBs on a lipid basis, previous studies found this method of preservation to be useful for at least one month (Schecter, A., Pavuk, M., Päpke, O., Malisch, R., 2004. The use of potassium dichromate and ethyl alcohol as blood preservatives for analysis of organochlorine contaminants. Chemosphere 57, 1-7). However blood stored at -70 degrees C and at 22 degrees C with potassium dichromate gave similar results when expressed on a wet weight basis."
1234184,Kayouka et al. 2009,Acute renal failure alters the kinetics of pralidoxime in rats,"There is a trend towards increasing doses of pralidoxime to treat human organophosphate poisonings that may have relevance in subpopulations. Indeed, pralidoxime is eliminated unchanged by the renal route. This study assesses the effect of renal failure on the kinetics of pralidoxime in a rat model of acute renal failure induced by potassium dichromate administration. On the first day, Sprague-Dawley rats received subcutaneously potassium dichromate (study) or saline (control). Forty-eight hours post-injection, animals received pralidoxime methylsulfate (50mg/kg of pralidoxime base) intramuscularly. Blood specimens were sampled during 180min after the injection. Urine was collected daily during the 3 days of the study. Plasma pralidoxime concentrations were measured by liquid chromatography with electrochemical detection. There was a 2-fold increase in mean elimination half-life and a 2.5-fold increase in mean area under the curve in the study compared to the control group. The mean total body clearance was halved in the study compared to the control group. Our study showed acute renal failure does not modify the distribution of pralidoxime but significantly alters its elimination from plasma. These results suggest that dosages of pralidoxime should be adjusted in organophosphate-poisoned humans with renal failure when using high dosage regimen of pralidoxime.","Acute renal failure alters the kinetics of pralidoxime in rats Abs: There is a trend towards increasing doses of pralidoxime to treat human organophosphate poisonings that may have relevance in subpopulations. Indeed, pralidoxime is eliminated unchanged by the renal route. This study assesses the effect of renal failure on the kinetics of pralidoxime in a rat model of acute renal failure induced by potassium dichromate administration. On the first day, Sprague-Dawley rats received subcutaneously potassium dichromate (study) or saline (control). Forty-eight hours post-injection, animals received pralidoxime methylsulfate (50mg/kg of pralidoxime base) intramuscularly. Blood specimens were sampled during 180min after the injection. Urine was collected daily during the 3 days of the study. Plasma pralidoxime concentrations were measured by liquid chromatography with electrochemical detection. There was a 2-fold increase in mean elimination half-life and a 2.5-fold increase in mean area under the curve in the study compared to the control group. The mean total body clearance was halved in the study compared to the control group. Our study showed acute renal failure does not modify the distribution of pralidoxime but significantly alters its elimination from plasma. These results suggest that dosages of pralidoxime should be adjusted in organophosphate-poisoned humans with renal failure when using high dosage regimen of pralidoxime."
1234183,Lee et al. 2009,"Synthesis of C14,15-dihydro-C22,25-epi north unit of cephalostatin 1 via &quot;red-ox&quot; modifications of hecogenin acetate","The C14,15-dihydro-C22,25-epi north unit of cephalostatin 1 has been synthesized in 11 operations from commercially available hecogenin acetate via multiple reductions and oxidations. The key transformations include (i) Cr(VI)-catalyzed E-ring opening, (ii) C17 hydroxylation, and (iii) a base-triggered cyclization cascade.","Synthesis of C14,15-dihydro-C22,25-epi north unit of cephalostatin 1 via &quot;red-ox&quot; modifications of hecogenin acetate Abs: The C14,15-dihydro-C22,25-epi north unit of cephalostatin 1 has been synthesized in 11 operations from commercially available hecogenin acetate via multiple reductions and oxidations. The key transformations include (i) Cr(VI)-catalyzed E-ring opening, (ii) C17 hydroxylation, and (iii) a base-triggered cyclization cascade."
1234182,Pandey et al. 2009,Chromium (VI) induced changes in growth and root plasma membrane redox activities in pea plants,"The effect of chromium (Cr) on growth as well as root plasma membrane redox reactions and superoxide radical production was studied in pea (Pisum sativum L. cv. Azad) plants exposed for 7 days to 20 and 200 microM Cr (VI), respectively, supplied as potassium dichromate. The growth of pea plants declined significantly at 200 microM Cr, as indicated by reduced leaf area and biomass. Relative to the control plants (no Cr exposure), the Cr content of roots increased significantly, both at 20 and 200 microM Cr. Following exposure to 200 microM Cr, there was a significant increase in root lipid peroxidation and hydrogen peroxide (H(2)O(2)) content, while both the Fv/Fm ratio and chlorophyll content were reduced. Exposure to Cr increased NADPH-dependent superoxide production in pea root plasma membrane vesicles, with the effect being more significant at 200 microM Cr than at 20 microM Cr. Treatment with Cr rapidly increased the activities of NADPH oxidase: relative to the controls, plants exposed to 20 microM Cr showed approximately a 67% increase in activity while there was a threefold increase in those plants exposed to 200 microM Cr. NADH-ferricyanide oxido-reductase activity was found to be inhibited by 16 and 51% at 20 and 200 microM Cr, respectively. The results of this study suggest that exposure to excess Cr damages pea root plasma membrane structure and function, resulting in decreased photosynthesis and poor plant growth.","Chromium (VI) induced changes in growth and root plasma membrane redox activities in pea plants Abs: The effect of chromium (Cr) on growth as well as root plasma membrane redox reactions and superoxide radical production was studied in pea (Pisum sativum L. cv. Azad) plants exposed for 7 days to 20 and 200 microM Cr (VI), respectively, supplied as potassium dichromate. The growth of pea plants declined significantly at 200 microM Cr, as indicated by reduced leaf area and biomass. Relative to the control plants (no Cr exposure), the Cr content of roots increased significantly, both at 20 and 200 microM Cr. Following exposure to 200 microM Cr, there was a significant increase in root lipid peroxidation and hydrogen peroxide (H(2)O(2)) content, while both the Fv/Fm ratio and chlorophyll content were reduced. Exposure to Cr increased NADPH-dependent superoxide production in pea root plasma membrane vesicles, with the effect being more significant at 200 microM Cr than at 20 microM Cr. Treatment with Cr rapidly increased the activities of NADPH oxidase: relative to the controls, plants exposed to 20 microM Cr showed approximately a 67% increase in activity while there was a threefold increase in those plants exposed to 200 microM Cr. NADH-ferricyanide oxido-reductase activity was found to be inhibited by 16 and 51% at 20 and 200 microM Cr, respectively. The results of this study suggest that exposure to excess Cr damages pea root plasma membrane structure and function, resulting in decreased photosynthesis and poor plant growth."
1234180,Osterc et al. 2009,Saccharomyces cerevisiae: the effect of different forms and concentrations of iodine on uptake and yeast growth,"The essentiality of iodine for humans, especially in the early stages of life, is well recognized. The chemical forms of iodine in food supplements, infant formulae and iodated salt are either iodide (KI) or iodate (KIO(3)). Because there are no or rare data about iodine uptake by yeasts, we investigated the influence of different sources of iodine, as KI, KIO(3) and periodate (KIO(4)), on its uptake in and growth of the model yeast Saccharomyces cerevisiae. KIO(3) inhibited the growth of the yeast the most and already at a 400 microM initial concentration in the growth medium; the OD was reduced by 23% in comparison with the control, where no KIO(3) was added. The uptake of different iodine sources by the yeast S. cerevisiae was minimal, in total &lt;1%. Tracer experiments with radioactive (131)I added as KI showed that the yeast S. cerevisiae does not have the ability to transform KI into volatile species. We investigated the specificity of iodine uptake added as KIO(3) in the presence of Na(2)SeO(4) or ZnCl(2) or K(2)CrO(4) in the growth medium, and it was found that chromate had the most influence on reduction of KIO(3) uptake.","Saccharomyces cerevisiae: the effect of different forms and concentrations of iodine on uptake and yeast growth Abs: The essentiality of iodine for humans, especially in the early stages of life, is well recognized. The chemical forms of iodine in food supplements, infant formulae and iodated salt are either iodide (KI) or iodate (KIO(3)). Because there are no or rare data about iodine uptake by yeasts, we investigated the influence of different sources of iodine, as KI, KIO(3) and periodate (KIO(4)), on its uptake in and growth of the model yeast Saccharomyces cerevisiae. KIO(3) inhibited the growth of the yeast the most and already at a 400 microM initial concentration in the growth medium; the OD was reduced by 23% in comparison with the control, where no KIO(3) was added. The uptake of different iodine sources by the yeast S. cerevisiae was minimal, in total &lt;1%. Tracer experiments with radioactive (131)I added as KI showed that the yeast S. cerevisiae does not have the ability to transform KI into volatile species. We investigated the specificity of iodine uptake added as KIO(3) in the presence of Na(2)SeO(4) or ZnCl(2) or K(2)CrO(4) in the growth medium, and it was found that chromate had the most influence on reduction of KIO(3) uptake."
1234179,Sierra-Alvarez 2009,"Removal of copper, chromium and arsenic from preservative-treated wood by chemical extraction-fungal bioleaching","Large volumes of preservative-treated wood containing toxic Cr, Cu and As salts are decommissioned worldwide. This study investigated the effectiveness of solid-state fermentation with copper-tolerant brown-rot fungi for the remediation of wood treated with chromated copper arsenate (CCA) and acid copper chromate (ACC) formulations. Treatment of CCA- and ACC-wood with the most effective strain, Antrodia vaillantii FRLP-14G, attained extensive leaching of As and/or Cr, but Cu elimination was poor (&lt;18%). Additional research showed that a variety of organic acids, including citrate, are effective Cu extractants. Based on these findings, a process combining chemical extraction and subsequent fungal treatment was developed that proved highly effective in removing inorganic pollutants from CCA-wood. Extraction of CCA-wood with citric acid (30 mM, pH 3.10) followed by a 28-day solid-state fermentation period removed 87% Cu, 80% Cr, and 100% As. These results indicate the potential of the two-stage process for the remediation of preservative-treated wood.","Removal of copper, chromium and arsenic from preservative-treated wood by chemical extraction-fungal bioleaching Abs: Large volumes of preservative-treated wood containing toxic Cr, Cu and As salts are decommissioned worldwide. This study investigated the effectiveness of solid-state fermentation with copper-tolerant brown-rot fungi for the remediation of wood treated with chromated copper arsenate (CCA) and acid copper chromate (ACC) formulations. Treatment of CCA- and ACC-wood with the most effective strain, Antrodia vaillantii FRLP-14G, attained extensive leaching of As and/or Cr, but Cu elimination was poor (&lt;18%). Additional research showed that a variety of organic acids, including citrate, are effective Cu extractants. Based on these findings, a process combining chemical extraction and subsequent fungal treatment was developed that proved highly effective in removing inorganic pollutants from CCA-wood. Extraction of CCA-wood with citric acid (30 mM, pH 3.10) followed by a 28-day solid-state fermentation period removed 87% Cu, 80% Cr, and 100% As. These results indicate the potential of the two-stage process for the remediation of preservative-treated wood."
1234178,Reynolds et al. 2009,Rapid DNA double-strand breaks resulting from processing of Cr-DNA cross-links by both MutS dimers,"Mismatch repair (MMR) strongly enhances cyto- and genotoxicity of several chemotherapeutic agents and environmental carcinogens. DNA double-strand breaks (DSB) formed after two replication cycles play a major role in MMR-dependent cell death by DNA alkylating drugs. Here, we examined DNA damage detection and the mechanisms of the unusually rapid induction of DSB by MMR proteins in response to carcinogenic chromium(VI). We found that MSH2-MSH6 (MutSalpha) dimer effectively bound DNA probes containing ascorbate-Cr-DNA and cysteine-Cr-DNA cross-links. Binary Cr-DNA adducts, the most abundant form of Cr-DNA damage, were poor substrates for MSH2-MSH6, and their toxicity in cells was weak and MMR independent. Although not involved in the initial recognition of Cr-DNA damage, MSH2-MSH3 (MutSbeta) complex was essential for the induction of DSB, micronuclei, and apoptosis in human cells by chromate. In situ fractionation of Cr-treated cells revealed MSH6 and MSH3 chromatin foci that originated in late S phase and did not require replication of damaged DNA. Formation of MSH3 foci was MSH6 and MLH1 dependent, whereas MSH6 foci were unaffected by MSH3 status. DSB production was associated with progression of cells from S into G(2) phase and was completely blocked by the DNA synthesis inhibitor aphidicolin. Interestingly, chromosome 3 transfer into MSH3-null HCT116 cells activated an alternative, MSH3-like activity that restored dinucleotide repeat stability and sensitivity to chromate. Thus, sequential recruitment and unprecedented cooperation of MutSalpha and MutSbeta branches of MMR in processing of Cr-DNA cross-links is the main cause of DSB and chromosomal breakage at low and moderate Cr(VI) doses.","Rapid DNA double-strand breaks resulting from processing of Cr-DNA cross-links by both MutS dimers Abs: Mismatch repair (MMR) strongly enhances cyto- and genotoxicity of several chemotherapeutic agents and environmental carcinogens. DNA double-strand breaks (DSB) formed after two replication cycles play a major role in MMR-dependent cell death by DNA alkylating drugs. Here, we examined DNA damage detection and the mechanisms of the unusually rapid induction of DSB by MMR proteins in response to carcinogenic chromium(VI). We found that MSH2-MSH6 (MutSalpha) dimer effectively bound DNA probes containing ascorbate-Cr-DNA and cysteine-Cr-DNA cross-links. Binary Cr-DNA adducts, the most abundant form of Cr-DNA damage, were poor substrates for MSH2-MSH6, and their toxicity in cells was weak and MMR independent. Although not involved in the initial recognition of Cr-DNA damage, MSH2-MSH3 (MutSbeta) complex was essential for the induction of DSB, micronuclei, and apoptosis in human cells by chromate. In situ fractionation of Cr-treated cells revealed MSH6 and MSH3 chromatin foci that originated in late S phase and did not require replication of damaged DNA. Formation of MSH3 foci was MSH6 and MLH1 dependent, whereas MSH6 foci were unaffected by MSH3 status. DSB production was associated with progression of cells from S into G(2) phase and was completely blocked by the DNA synthesis inhibitor aphidicolin. Interestingly, chromosome 3 transfer into MSH3-null HCT116 cells activated an alternative, MSH3-like activity that restored dinucleotide repeat stability and sensitivity to chromate. Thus, sequential recruitment and unprecedented cooperation of MutSalpha and MutSbeta branches of MMR in processing of Cr-DNA cross-links is the main cause of DSB and chromosomal breakage at low and moderate Cr(VI) doses."
1234177,Fai and  Grant 2009,A comparative study of Saccharomyces cerevisiae sensitivity against eight yeast species sensitivities to a range of toxicants,"Fungi are widespread and very important in many ecosystems but the extensive use of pesticides can adversely affect beneficial fungi. The yeast, Saccharomyces cerevisiae has been proposed for the toxicological assessment of the effects of environmental pollutants on non-target fungi. To assess whether S. cerevisiae is a good representative of the immense ecological and phylogenetic diversity of yeasts, we compare the sensitivity of eight other yeasts from diverse phylogenetic taxa to a range of toxicants and environmental samples. Sensitivity was assessed using both the growth inhibition and alamar blue (resorufin fluorescence inhibition) bioassays. The growth inhibition bioassay showed that all yeast species had similar dose-response curves for the five organic fungicides and two environmental samples used. However, two yeast species, Trichosporon dulcitum and Pseudozyma fusiformata, were a great deal more sensitive than all others to CuSO4 and K2Cr2O7 while S. cerevisiae was the most tolerant to these chemicals. S. cerevisiae, however, showed similar sensitivity as other species to all toxicants in the resorufin fluorescence inhibition bioassay. It can therefore be used as a representative yeast species for assessing effects of environmental contaminants to non-target fungi and in the screening of chemical libraries for fungicidal activity.","A comparative study of Saccharomyces cerevisiae sensitivity against eight yeast species sensitivities to a range of toxicants Abs: Fungi are widespread and very important in many ecosystems but the extensive use of pesticides can adversely affect beneficial fungi. The yeast, Saccharomyces cerevisiae has been proposed for the toxicological assessment of the effects of environmental pollutants on non-target fungi. To assess whether S. cerevisiae is a good representative of the immense ecological and phylogenetic diversity of yeasts, we compare the sensitivity of eight other yeasts from diverse phylogenetic taxa to a range of toxicants and environmental samples. Sensitivity was assessed using both the growth inhibition and alamar blue (resorufin fluorescence inhibition) bioassays. The growth inhibition bioassay showed that all yeast species had similar dose-response curves for the five organic fungicides and two environmental samples used. However, two yeast species, Trichosporon dulcitum and Pseudozyma fusiformata, were a great deal more sensitive than all others to CuSO4 and K2Cr2O7 while S. cerevisiae was the most tolerant to these chemicals. S. cerevisiae, however, showed similar sensitivity as other species to all toxicants in the resorufin fluorescence inhibition bioassay. It can therefore be used as a representative yeast species for assessing effects of environmental contaminants to non-target fungi and in the screening of chemical libraries for fungicidal activity."
1234175,Grossman and  Ghosh 2009,Measurement of activated carbon and other black carbons in sediments,"Black carbon in sediment, present natively or added as a treatment amendment in the form of activated carbon, reduces contaminant bioavailability. Field evaluation of activated carbon effectiveness in reducing contaminant bioavailability requires accurate methods to measure the amendment in sediments. The most commonly used method to separate black carbon from natural organic matter in soils and sediments is low temperature (375 degrees C) thermal oxidation which resulted in significant losses of activated carbons. A method was developed to isolate activated carbon using a solution of concentrated sulfuric acid and potassium dichromate to oxidize the natural organic matter while preserving the activated carbon. The chemical oxidation method was applied to assess the delivery of activated carbon to sediments in a pilot-scale demonstration project carried out in Grasse River, NY. Using this method on sediment from the Grasse River, over 98% of the natural organic matter was removed while preserving at least 95% of the activated carbon. The method was also demonstrated on other carbonaceous geosorbents and native black carbon in several sediment samples.","Measurement of activated carbon and other black carbons in sediments Abs: Black carbon in sediment, present natively or added as a treatment amendment in the form of activated carbon, reduces contaminant bioavailability. Field evaluation of activated carbon effectiveness in reducing contaminant bioavailability requires accurate methods to measure the amendment in sediments. The most commonly used method to separate black carbon from natural organic matter in soils and sediments is low temperature (375 degrees C) thermal oxidation which resulted in significant losses of activated carbons. A method was developed to isolate activated carbon using a solution of concentrated sulfuric acid and potassium dichromate to oxidize the natural organic matter while preserving the activated carbon. The chemical oxidation method was applied to assess the delivery of activated carbon to sediments in a pilot-scale demonstration project carried out in Grasse River, NY. Using this method on sediment from the Grasse River, over 98% of the natural organic matter was removed while preserving at least 95% of the activated carbon. The method was also demonstrated on other carbonaceous geosorbents and native black carbon in several sediment samples."
1234173,Zhang et al. 2009,"Interactions of chromium (III) and chromium (VI) with bovine serum albumin studied by UV spectroscopy, circular dichroism, and fluorimetry","In the present work, the interactions of bovine serum albumin (BSA) with chromium (III) chloride, potassium dichromate, and chromate were studied by fluorescence, circular dichroism, and UV-vis absorbance spectroscopy. Fluorescence quenching of BSA by chromium (III) was found to be a dynamic process in the beginning, turning static at later stages. Spectroscopic data show that both dichromate and chromate bind in similar electrostatic fashion to BSA and does not follow the fluorescence quenching observation for chromium (III).","Interactions of chromium (III) and chromium (VI) with bovine serum albumin studied by UV spectroscopy, circular dichroism, and fluorimetry Abs: In the present work, the interactions of bovine serum albumin (BSA) with chromium (III) chloride, potassium dichromate, and chromate were studied by fluorescence, circular dichroism, and UV-vis absorbance spectroscopy. Fluorescence quenching of BSA by chromium (III) was found to be a dynamic process in the beginning, turning static at later stages. Spectroscopic data show that both dichromate and chromate bind in similar electrostatic fashion to BSA and does not follow the fluorescence quenching observation for chromium (III)."
1234171,Jindal et al. 2009,Contact sensitization in venous eczema: preliminary results of patch testing with Indian standard series and topical medicaments,"<strong>BACKGROUND AND AIMS: </strong>Elimination of allergens/topical medications causing contact dermatitis in venous eczema, which poses a significant problem in its chronicity and treatment, provides the basis for better therapeutic outcome. Our objective was to determine the pattern of contact sensitization in venous eczema patients in Himachal Pradesh (India).<br /><br /><strong>METHODS: </strong>Thirty-four patients (M:F, 31:3) and 10 controls (M:F, 6:4) were patch tested with Indian standard series and 10 commonly used topical medicaments.<br /><br /><strong>RESULTS: </strong>Positive patch test results were seen in 50% (M:F, 16:1) of the patients. Common allergens were Fragrance mix (15%), p-phenylendiamine (15%), nickel (9%), wool alcohol (9%), chinoform (9%), balsum of Peru (5%), cobalt chloride (5%), potassium dichromate (3%), epoxy resin (3%), thiuram mix (3%) and formaldehyde (3%). Only sisomycin and miconazole among the topical medications elicited a positive patch test reaction in 3 and 5% patients, respectively. Neomycin contact sensitivity was not seen in any of the patients. One patient who had exacerbation of venous eczema following accidental application of topical diclofenac showed a positive patch test reaction to it.<br /><br /><strong>CONCLUSIONS: </strong>Patch test should be used to identify the topical agents that may be responsible for perpetuation or aggravation of eczema, especially in patients who do not improve despite adequate treatment of other underlying cause(s).","Contact sensitization in venous eczema: preliminary results of patch testing with Indian standard series and topical medicaments Abs: <strong>BACKGROUND AND AIMS: </strong>Elimination of allergens/topical medications causing contact dermatitis in venous eczema, which poses a significant problem in its chronicity and treatment, provides the basis for better therapeutic outcome. Our objective was to determine the pattern of contact sensitization in venous eczema patients in Himachal Pradesh (India).<br /><br /><strong>METHODS: </strong>Thirty-four patients (M:F, 31:3) and 10 controls (M:F, 6:4) were patch tested with Indian standard series and 10 commonly used topical medicaments.<br /><br /><strong>RESULTS: </strong>Positive patch test results were seen in 50% (M:F, 16:1) of the patients. Common allergens were Fragrance mix (15%), p-phenylendiamine (15%), nickel (9%), wool alcohol (9%), chinoform (9%), balsum of Peru (5%), cobalt chloride (5%), potassium dichromate (3%), epoxy resin (3%), thiuram mix (3%) and formaldehyde (3%). Only sisomycin and miconazole among the topical medications elicited a positive patch test reaction in 3 and 5% patients, respectively. Neomycin contact sensitivity was not seen in any of the patients. One patient who had exacerbation of venous eczema following accidental application of topical diclofenac showed a positive patch test reaction to it.<br /><br /><strong>CONCLUSIONS: </strong>Patch test should be used to identify the topical agents that may be responsible for perpetuation or aggravation of eczema, especially in patients who do not improve despite adequate treatment of other underlying cause(s)."
1234170,Llanos-Rivera et al. 2009,A new developmental toxicity test for pelagic fish using anchoveta (Engraulis ringens J.),"A series of six 96-h static bioassays were performed to validate the use of anchoveta (Engraulis ringens) embryos as test organisms for ecotoxicological studies. The standardization protocol utilized potassium dichromate (K(2)Cr(2)O(7)) as a reference toxicant and egg mortality as the endpoint. The results indicated that the mean sensitivity of anchoveta embryos to potassium dichromate was 156.1 mg L(-1) (range: 131-185 mg L(-1)). The statistical data analysis showed high homogeneity in LC50 values among bioassays (variation coefficient = 11.02%). These results demonstrated that the protocol and handling procedures implemented for the anchoveta embryo bioassays comply with international standards for intra-laboratory precision. After secondary treatment, an effluent from a modern Kraft pulp mill was tested for E. ringens embryo toxicity, finding no significant differences from the controls.","A new developmental toxicity test for pelagic fish using anchoveta (Engraulis ringens J.) Abs: A series of six 96-h static bioassays were performed to validate the use of anchoveta (Engraulis ringens) embryos as test organisms for ecotoxicological studies. The standardization protocol utilized potassium dichromate (K(2)Cr(2)O(7)) as a reference toxicant and egg mortality as the endpoint. The results indicated that the mean sensitivity of anchoveta embryos to potassium dichromate was 156.1 mg L(-1) (range: 131-185 mg L(-1)). The statistical data analysis showed high homogeneity in LC50 values among bioassays (variation coefficient = 11.02%). These results demonstrated that the protocol and handling procedures implemented for the anchoveta embryo bioassays comply with international standards for intra-laboratory precision. After secondary treatment, an effluent from a modern Kraft pulp mill was tested for E. ringens embryo toxicity, finding no significant differences from the controls."
1234169,Xiang et al. 2009,Non-invasive methods for identifying oocysts of Sarcocystis spp. from definitive hosts,"Because the excreted sporocysts and/or oocysts of various species of Sarcocystis may not be discriminated morphologically, we sought to validate a diagnostic technique based on variation in the 18S rDNA sequence. Oocysts and/or sporocysts from three taxa of Sarcocystis were collected from human, feline, and canine definitive hosts that had fed upon meats infected with the muscle cysts of Sarcocystis hominis, Sarcocystis fusiformis and a species of Sarcocystis from water buffalo that could not be distinguished from Sarcocystis cruzi. Using a new collection method employing filter paper, these excreted oocysts and sporocysts were subjected to DNA extraction, as were the corresponding muscle cysts. Methods employing PCR-RFLP and DNA sequencing of a partial 18S rDNA gene (ssrRNA) sequence were then used to successfully distinguish among the three taxa. The same, unique restriction digestion pattern characterizes the tissue cysts and oocysts and/or sporocysts of each parasite taxon. The technique makes possible amplification and identification of species specific gene sequences based on DNA extracted from as few as 7 excreted sporocysts (the equivalent of 3 and 1/2 oocysts) from freshly prepared material, or as few as 50 sporocysts from feces samples that had been stored in potassium dichromate (K2Cr2O7) for as long as 6 years. This represents the first report using molecular diagnostic procedures to diagnose oocysts of Sarcocystis in faecal samples, describing a valuable new tool for studying the epidemiology of various Sarcocystis species.","Non-invasive methods for identifying oocysts of Sarcocystis spp. from definitive hosts Abs: Because the excreted sporocysts and/or oocysts of various species of Sarcocystis may not be discriminated morphologically, we sought to validate a diagnostic technique based on variation in the 18S rDNA sequence. Oocysts and/or sporocysts from three taxa of Sarcocystis were collected from human, feline, and canine definitive hosts that had fed upon meats infected with the muscle cysts of Sarcocystis hominis, Sarcocystis fusiformis and a species of Sarcocystis from water buffalo that could not be distinguished from Sarcocystis cruzi. Using a new collection method employing filter paper, these excreted oocysts and sporocysts were subjected to DNA extraction, as were the corresponding muscle cysts. Methods employing PCR-RFLP and DNA sequencing of a partial 18S rDNA gene (ssrRNA) sequence were then used to successfully distinguish among the three taxa. The same, unique restriction digestion pattern characterizes the tissue cysts and oocysts and/or sporocysts of each parasite taxon. The technique makes possible amplification and identification of species specific gene sequences based on DNA extracted from as few as 7 excreted sporocysts (the equivalent of 3 and 1/2 oocysts) from freshly prepared material, or as few as 50 sporocysts from feces samples that had been stored in potassium dichromate (K2Cr2O7) for as long as 6 years. This represents the first report using molecular diagnostic procedures to diagnose oocysts of Sarcocystis in faecal samples, describing a valuable new tool for studying the epidemiology of various Sarcocystis species."
1234168,Demir et al. 2009,Antigenotoxic effects of Citrus aurentium L. fruit peel oil on mutagenicity of two alkylating agents and two metals in the Drosophila wing spot test,"Antigenotoxic effects of Citrus aurentium L. (Rutaceae) fruit peel oil (CPO) in combination with mutagenic metals and alkylating agents were studied using the wing spot test of D. melanogaster. The four reference mutagens, potassium dichromate (K2Cr2O7), cobalt chloride (CoCl2), ethylmethanesulfonate (EMS), and N-ethyl-N-nitrosourea (ENU) were clearly genotoxic. CPO alone at doses from 0.1 to 0.5% in Tween 80 was not mutagenic and did not enhance the mutagenic effect of the reference mutagens. However, antigenotoxic effects of CPO were clearly demonstrated in chronic cotreatments with mutagens and oil, by a significant decrease in wing spots induced by all four mutagens. The D. melanogaster wing spot test was found to be a suitable assay for detecting antigenotoxic effects in vivo.","Antigenotoxic effects of Citrus aurentium L. fruit peel oil on mutagenicity of two alkylating agents and two metals in the Drosophila wing spot test Abs: Antigenotoxic effects of Citrus aurentium L. (Rutaceae) fruit peel oil (CPO) in combination with mutagenic metals and alkylating agents were studied using the wing spot test of D. melanogaster. The four reference mutagens, potassium dichromate (K2Cr2O7), cobalt chloride (CoCl2), ethylmethanesulfonate (EMS), and N-ethyl-N-nitrosourea (ENU) were clearly genotoxic. CPO alone at doses from 0.1 to 0.5% in Tween 80 was not mutagenic and did not enhance the mutagenic effect of the reference mutagens. However, antigenotoxic effects of CPO were clearly demonstrated in chronic cotreatments with mutagens and oil, by a significant decrease in wing spots induced by all four mutagens. The D. melanogaster wing spot test was found to be a suitable assay for detecting antigenotoxic effects in vivo."
1234167,Botha and  Ross 2008,A nuclear magnetic resonance spectroscopy comparison of 3C trituration derived and 4C trituration derived remedies,"<strong>BACKGROUND: </strong>Trituration of base substances, commonly to the 3cH level, is the cornerstone of the homeopathic pharmaceutical process or insoluble solutions. Becker and Ehrler claim that trituration to 4cH gives a new, spiritual dimension to the homoeopathic medicine picture.<br /><br /><strong>AIM AND METHOD: </strong>This study sought to establish whether the claim that C4-derived potencies possess different physicochemical qualities to the homoeopathic medicines derived from a 3cH trituration is valid. All potencies were produced by hand according to the German Homoeopathic Pharmacopoeia (GHP). Five different samples were analysed using Nuclear Magnetic Resonance (NMR) Spectroscopy.<br /><br /><strong>RESULTS: </strong>The results indicated a significant difference between the 12cH samples of potassium dichromate (Kalium bichromicum) produced from 3cH and 4cH triturations. This was especially prominent in the chemical shift values of all four peaks and the relative integration levels of the H(2)O, OH and CH(3) peaks when comparing two sample groups.<br /><br /><strong>CONCLUSION: </strong>Trituration plays a part in the development of physicochemical properties specific to homoeopathic medicines. The higher the level of trituration, the more pronounced is the alteration of the physical structure of the active ingredient. The study concludes that 4cH potencies are physicochemically distinct from 3cH-derived potencies (as currently employed).","A nuclear magnetic resonance spectroscopy comparison of 3C trituration derived and 4C trituration derived remedies Abs: <strong>BACKGROUND: </strong>Trituration of base substances, commonly to the 3cH level, is the cornerstone of the homeopathic pharmaceutical process or insoluble solutions. Becker and Ehrler claim that trituration to 4cH gives a new, spiritual dimension to the homoeopathic medicine picture.<br /><br /><strong>AIM AND METHOD: </strong>This study sought to establish whether the claim that C4-derived potencies possess different physicochemical qualities to the homoeopathic medicines derived from a 3cH trituration is valid. All potencies were produced by hand according to the German Homoeopathic Pharmacopoeia (GHP). Five different samples were analysed using Nuclear Magnetic Resonance (NMR) Spectroscopy.<br /><br /><strong>RESULTS: </strong>The results indicated a significant difference between the 12cH samples of potassium dichromate (Kalium bichromicum) produced from 3cH and 4cH triturations. This was especially prominent in the chemical shift values of all four peaks and the relative integration levels of the H(2)O, OH and CH(3) peaks when comparing two sample groups.<br /><br /><strong>CONCLUSION: </strong>Trituration plays a part in the development of physicochemical properties specific to homoeopathic medicines. The higher the level of trituration, the more pronounced is the alteration of the physical structure of the active ingredient. The study concludes that 4cH potencies are physicochemically distinct from 3cH-derived potencies (as currently employed)."
1234165,Perreault et al. 2009,Dichromate effect on energy dissipation of photosystem II and photosystem I in Chlamydomonas reinhardtii,"In this study, we investigated the energy dissipation processes via photosystem II and photosystem I activity in green alga Chlamydomonas reinhardtii exposed to dichromate inhibitory effect. Quantum yield of photosystem II and also photosystem I were highly decreased by dichromate effect. Such inhibition by dichromate induced strong quenching effect on rapid OJIP fluorescence transients, indicating deterioration of photosystem II electron transport via plastoquinone pool toward photosystem I. The decrease of energy dissipation dependent on electron transport of photosystem II and photosystem I by dichromate effect was associated with strong increase of non-photochemical energy dissipation processes. By showing strong effect of dichromate on acceptor side of photosystem I, we indicated that dichromate inhibitory effect was not associated only with PSII electron transport. Here, we found that energy dissipation via photosystem I was limited by its electron acceptor side. By the analysis of P700 oxido-reduction state with methylviolagen as an exogenous PSI electron transport mediator, we showed that PSI electron transport discrepancy induced by dichromate effect was also caused by inhibitory effect located beyond photosystem I. Therefore, these results demonstrated that dichromate has different sites of inhibition which are associated with photosystem II, photosystem I and electron transport sink beyond photosystems.","Dichromate effect on energy dissipation of photosystem II and photosystem I in Chlamydomonas reinhardtii Abs: In this study, we investigated the energy dissipation processes via photosystem II and photosystem I activity in green alga Chlamydomonas reinhardtii exposed to dichromate inhibitory effect. Quantum yield of photosystem II and also photosystem I were highly decreased by dichromate effect. Such inhibition by dichromate induced strong quenching effect on rapid OJIP fluorescence transients, indicating deterioration of photosystem II electron transport via plastoquinone pool toward photosystem I. The decrease of energy dissipation dependent on electron transport of photosystem II and photosystem I by dichromate effect was associated with strong increase of non-photochemical energy dissipation processes. By showing strong effect of dichromate on acceptor side of photosystem I, we indicated that dichromate inhibitory effect was not associated only with PSII electron transport. Here, we found that energy dissipation via photosystem I was limited by its electron acceptor side. By the analysis of P700 oxido-reduction state with methylviolagen as an exogenous PSI electron transport mediator, we showed that PSI electron transport discrepancy induced by dichromate effect was also caused by inhibitory effect located beyond photosystem I. Therefore, these results demonstrated that dichromate has different sites of inhibition which are associated with photosystem II, photosystem I and electron transport sink beyond photosystems."
1234163,Becerra-Torres et al. 2009,Potassium dichromate-induced changes on urinary-specific activities of gamma-glutamyl transpeptidase and alanine aminopeptidase enzymes,"It has been reported that potassium dichromate-induced nephrotoxicity is evidenced by diminution in creatinine clearance, increase in urinary protein, and structural damage to the proximal tubules. Damage to tissue often leads to the release of enzymes from the injured cells into the extracellular fluids. The aim of this study was to establish whether potassium dichromate induces changes in the urinary-specific activities of gamma-glutamyl transpeptidase and alanine aminopeptidase enzymes. Our results show that the administration of a single intraperitoneal dose of potassium dichromate decreased the activity of such enzymes in urine.","Potassium dichromate-induced changes on urinary-specific activities of gamma-glutamyl transpeptidase and alanine aminopeptidase enzymes Abs: It has been reported that potassium dichromate-induced nephrotoxicity is evidenced by diminution in creatinine clearance, increase in urinary protein, and structural damage to the proximal tubules. Damage to tissue often leads to the release of enzymes from the injured cells into the extracellular fluids. The aim of this study was to establish whether potassium dichromate induces changes in the urinary-specific activities of gamma-glutamyl transpeptidase and alanine aminopeptidase enzymes. Our results show that the administration of a single intraperitoneal dose of potassium dichromate decreased the activity of such enzymes in urine."
1234162,Charalampidis et al. 2009,Blue CrO5 assay: a novel spectrophotometric method for the evaluation of the antioxidant and oxidant capacity of various biological substances,"Oxidative stress plays a pivotal role in the ageing process and in the pathogenesis of numerable diseases. The quantification of the phenomenon is of paramount importance. In the present study, we introduce a novel and simple assay, the Blue CrO(5) assay, for the evaluation of the oxidant and antioxidant capacity of various biological samples and known antioxidants. Chromium peroxide (CrO(5)) is produced by ammonium dichromate in an acidic environment in the presence of H(2)O(2). It is a deep blue potent oxidant compound, miscible and relatively stable in polar organic solvents, that can be easily measured by spectrophotometry. Its reduction by known antioxidants, both water- and lipid-soluble (ascorbate and alpha-tocopherol, respectively, in this study), detected spectrophotometrically as a decrease in the absorption and depicted in EPR spectra, can act as a measure of the antioxidant capacity of a certain compound. The assay displays significant sensitivity, stability, linearity, specificity and repeatability.","Blue CrO5 assay: a novel spectrophotometric method for the evaluation of the antioxidant and oxidant capacity of various biological substances Abs: Oxidative stress plays a pivotal role in the ageing process and in the pathogenesis of numerable diseases. The quantification of the phenomenon is of paramount importance. In the present study, we introduce a novel and simple assay, the Blue CrO(5) assay, for the evaluation of the oxidant and antioxidant capacity of various biological samples and known antioxidants. Chromium peroxide (CrO(5)) is produced by ammonium dichromate in an acidic environment in the presence of H(2)O(2). It is a deep blue potent oxidant compound, miscible and relatively stable in polar organic solvents, that can be easily measured by spectrophotometry. Its reduction by known antioxidants, both water- and lipid-soluble (ascorbate and alpha-tocopherol, respectively, in this study), detected spectrophotometrically as a decrease in the absorption and depicted in EPR spectra, can act as a measure of the antioxidant capacity of a certain compound. The assay displays significant sensitivity, stability, linearity, specificity and repeatability."
1234161,Chang and  Spitzer 2009,"Spontaneous calcium spike activity in embryonic spinal neurons is regulated by developmental expression of the Na+, K+-ATPase beta3 subunit","Different types and patterns of spontaneous electrical activity drive many aspects of neuronal differentiation. Neurons in the developing Xenopus spinal cord exhibit calcium spikes, which regulate gene transcription and neurotransmitter specification. The ionic currents necessary for spike production have been described. However, the mechanisms that generate the onset of this activity and the basis of its regulation remain unclear. Although signaling molecules appear to act on plasma membrane receptors to trigger calcium spike activity, other mechanisms for spontaneous calcium spike regulation may exist as well. Here, we analyze the developmental expression of the Na(+), K(+)-ATPase beta3 subunit in Xenopus tropicalis embryos and show that its levels are downregulated at a time during embryonic development that coincides with the onset of prominent calcium spike activity in spinal neurons. Inhibition of an earlier increase in beta3 expression leads to more depolarized resting membrane potentials and results in later reduction of spike activity. This suppression of beta3 levels also reduces expression of the store-operated calcium channel subunit, Orai1. These findings suggest that the Na(+), K(+)-ATPase plays a role in initiating calcium spike activity and regulating calcium homeostasis.","Spontaneous calcium spike activity in embryonic spinal neurons is regulated by developmental expression of the Na+, K+-ATPase beta3 subunit Abs: Different types and patterns of spontaneous electrical activity drive many aspects of neuronal differentiation. Neurons in the developing Xenopus spinal cord exhibit calcium spikes, which regulate gene transcription and neurotransmitter specification. The ionic currents necessary for spike production have been described. However, the mechanisms that generate the onset of this activity and the basis of its regulation remain unclear. Although signaling molecules appear to act on plasma membrane receptors to trigger calcium spike activity, other mechanisms for spontaneous calcium spike regulation may exist as well. Here, we analyze the developmental expression of the Na(+), K(+)-ATPase beta3 subunit in Xenopus tropicalis embryos and show that its levels are downregulated at a time during embryonic development that coincides with the onset of prominent calcium spike activity in spinal neurons. Inhibition of an earlier increase in beta3 expression leads to more depolarized resting membrane potentials and results in later reduction of spike activity. This suppression of beta3 levels also reduces expression of the store-operated calcium channel subunit, Orai1. These findings suggest that the Na(+), K(+)-ATPase plays a role in initiating calcium spike activity and regulating calcium homeostasis."
1234160,Kvíderová 2010,Rapid algal toxicity assay using variable chlorophyll fluorescence for Chlorella kessleri (chlorophyta),"Three methods of algal assays--the standard assay, microassay, and the proposed fluorescence assay--are compared from the point of view of reliability of EC50 detection, the minimum required time for the detection, sensitivity of individual measurement, i.e. at which cell density the particular assay can be used for EC50 estimation, and the time stability of the EC50 values. The assays were performed with green alga Chlorella kessleri strain LARG/1 growing in potassium dichromate solution in Z-medium ranging from 0.01 to 100 mg Cr L?¹. The inoculation cell density was set according to the standards to 10? cells mL?¹ and according to spectrophotometer/plate reader detection limit. The average EC50 ranged from 0.096 to 0.649 mg Cr L?¹ and there were no significant differences in EC50 between the assay type and the inoculation methods with the exception of the significant difference between EC(c)50?? (EC50 established from biomass measured as chlorophyll a concentration after 72 h of cultivation) in the standard assay and EC(r)50 (EC50 derived from growth rate) in the microassay in the standard inoculation experiment due to low variability of their values. The EC(f)50 (EC50 derived from variable fluorescence measurement) values correspond to EC50 values derived from the growth rates. Fluorescence measurement revealed the toxic effect of the chromium after 24 h of exposure at cell density of 5 x 10? cells mL?¹, less by half than other used assay methods. The positive correlation of EC(f)50 and time was found in the standard inoculation experiment but opposite effect was observed at the spectrophotometric one.","Rapid algal toxicity assay using variable chlorophyll fluorescence for Chlorella kessleri (chlorophyta) Abs: Three methods of algal assays--the standard assay, microassay, and the proposed fluorescence assay--are compared from the point of view of reliability of EC50 detection, the minimum required time for the detection, sensitivity of individual measurement, i.e. at which cell density the particular assay can be used for EC50 estimation, and the time stability of the EC50 values. The assays were performed with green alga Chlorella kessleri strain LARG/1 growing in potassium dichromate solution in Z-medium ranging from 0.01 to 100 mg Cr L?¹. The inoculation cell density was set according to the standards to 10? cells mL?¹ and according to spectrophotometer/plate reader detection limit. The average EC50 ranged from 0.096 to 0.649 mg Cr L?¹ and there were no significant differences in EC50 between the assay type and the inoculation methods with the exception of the significant difference between EC(c)50?? (EC50 established from biomass measured as chlorophyll a concentration after 72 h of cultivation) in the standard assay and EC(r)50 (EC50 derived from growth rate) in the microassay in the standard inoculation experiment due to low variability of their values. The EC(f)50 (EC50 derived from variable fluorescence measurement) values correspond to EC50 values derived from the growth rates. Fluorescence measurement revealed the toxic effect of the chromium after 24 h of exposure at cell density of 5 x 10? cells mL?¹, less by half than other used assay methods. The positive correlation of EC(f)50 and time was found in the standard inoculation experiment but opposite effect was observed at the spectrophotometric one."
1234159,Wilke and  Robertson 2009,Preservation of Giardia cysts in stool samples for subsequent PCR analysis,"Genotyping of Giardia duodenalis cysts in faecal samples has become a regularly employed tool by researchers investigating different aspects of the epidemiology and pathology of Giardia infection in human and animal populations. However, such investigations are often limited to some extent by lack of PCR amplification from a proportion of the samples, and this often seems to be associated with the storage medium used for the samples. Various different storage media have been used in different studies, but investigation of which storage media are most appropriate and which may compromise subsequent PCR investigations has not been systematically explored to date. In this study, 4 different, commonly used storage media were investigated for their effects over time on subsequent PCR amplification of DNA from Giardia cysts in stool samples. Microscopic examination of the samples and real-time PCR were used to investigate 7 different samples over a period of 3 months. Our findings indicate that storage in ethanol or potassium dichromate at 4 degrees C gave the best results and, that if immunomagnetic separation was used prior to PCR (as may be appropriate for samples with low cyst numbers), then storage in potassium dichromate gave the best results.","Preservation of Giardia cysts in stool samples for subsequent PCR analysis Abs: Genotyping of Giardia duodenalis cysts in faecal samples has become a regularly employed tool by researchers investigating different aspects of the epidemiology and pathology of Giardia infection in human and animal populations. However, such investigations are often limited to some extent by lack of PCR amplification from a proportion of the samples, and this often seems to be associated with the storage medium used for the samples. Various different storage media have been used in different studies, but investigation of which storage media are most appropriate and which may compromise subsequent PCR investigations has not been systematically explored to date. In this study, 4 different, commonly used storage media were investigated for their effects over time on subsequent PCR amplification of DNA from Giardia cysts in stool samples. Microscopic examination of the samples and real-time PCR were used to investigate 7 different samples over a period of 3 months. Our findings indicate that storage in ethanol or potassium dichromate at 4 degrees C gave the best results and, that if immunomagnetic separation was used prior to PCR (as may be appropriate for samples with low cyst numbers), then storage in potassium dichromate gave the best results."
1234158,Oliveira et al. 2010,Evaluation of in vivo reproductive toxicity of potassium chromate in male mice,"To evaluate the effects of potassium chromate on mice sperm cells after a short-term exposure, male ICR-CD1 mice were administered with 5 or 10mgK(2)CrO(4)/bw for 4 consecutive days. One group of mice was sacrificed at day 5, starting from the beginning of the experiment and another group was sacrificed at day 35. Testis and epididymis histology was evaluated by light microscopy and testicular cells populations were evaluated by flow cytometry (FCM). Spermatozoa were collected from the epididymis and their morphology and several functional parameters (density, motility, viability, mitochondrial function, acrosome integrity) were evaluated. Furthermore, DNA fragmentation and chromatin status of sperm cells were assessed at both experimental periods. Besides a reduction in seminiferous tubules diameter, exposure to potassium chromate did not induce further histopathological changes in mice testis or epididymis. These results were supported by the analysis of testicular cellular subpopulations by FCM. Concerning spermatozoa morphology, an increase in the percentage of multiple abnormalities and a decrease in the percentage of normal spermatozoa were found at days 5 and 35, respectively. Although spermatozoa mitochondrial function or viability was not affected, its motility was significantly reduced by potassium chromate exposure at both experimental periods. A decrease in acrosome integrity was found in mice injected with 10mgK(2)CrO(4)/bw after 35 days. Exposure to potassium chromate did not affect either DNA fragmentation or chromatin susceptibility to acid denaturation of sperm cells. In this work, we were able to show the effects of potassium chromate on spermatozoa physiological parameters such as motility, morphology and acrosome status and also demonstrate that the doses tested did not induce DNA damage to sperm cells after one spermatogenic cycle.","Evaluation of in vivo reproductive toxicity of potassium chromate in male mice Abs: To evaluate the effects of potassium chromate on mice sperm cells after a short-term exposure, male ICR-CD1 mice were administered with 5 or 10mgK(2)CrO(4)/bw for 4 consecutive days. One group of mice was sacrificed at day 5, starting from the beginning of the experiment and another group was sacrificed at day 35. Testis and epididymis histology was evaluated by light microscopy and testicular cells populations were evaluated by flow cytometry (FCM). Spermatozoa were collected from the epididymis and their morphology and several functional parameters (density, motility, viability, mitochondrial function, acrosome integrity) were evaluated. Furthermore, DNA fragmentation and chromatin status of sperm cells were assessed at both experimental periods. Besides a reduction in seminiferous tubules diameter, exposure to potassium chromate did not induce further histopathological changes in mice testis or epididymis. These results were supported by the analysis of testicular cellular subpopulations by FCM. Concerning spermatozoa morphology, an increase in the percentage of multiple abnormalities and a decrease in the percentage of normal spermatozoa were found at days 5 and 35, respectively. Although spermatozoa mitochondrial function or viability was not affected, its motility was significantly reduced by potassium chromate exposure at both experimental periods. A decrease in acrosome integrity was found in mice injected with 10mgK(2)CrO(4)/bw after 35 days. Exposure to potassium chromate did not affect either DNA fragmentation or chromatin susceptibility to acid denaturation of sperm cells. In this work, we were able to show the effects of potassium chromate on spermatozoa physiological parameters such as motility, morphology and acrosome status and also demonstrate that the doses tested did not induce DNA damage to sperm cells after one spermatogenic cycle."
1234157,Vannini et al. 2009,Proteomic analysis of chromate-induced modifications in Pseudokirchneriella subcapitata,"In this work, we have analyzed the changes in the protein expression profile elicited by chromium (Cr) exposure in the freshwater green alga Pseudokirchneriella subcapitata, a well known bio-indicator of water pollution. We tested two experimental conditions, namely 0.2 and 1ppm of potassium dichromate; this concentration range includes the environmentally-relevant concentrations. Results show that neither concentration of potassium dichromate tested inhibited algal growth. However, the proteomic approach allowed the identification of relevant modifications in protein expression. In fact, among 800 protein spots detected by two-dimensional electrophoresis, 16 Cr-regulated proteins, including predicted and novel ones, were identified using tandem mass spectromic protein analysis. The results demonstrate a Cr-specific action in altering several photosynthetic proteins, such as ribulose-1,5-bisphosphate carboxylase/oxygenase (RuBisCO), RuBisCO activase, Light Harvesting Chla/b protein complex, and stress related Chla/b binding protein1. Although Cr toxicity with respect to photosynthesis has been already documented, here we have identified, for the first time, the target proteins of this toxicity. Cr also induced a modulation of some proteins involved in the metabolism of the amino acids glutamine, arginine and methionine. These data are supported by changes in cellular polyamine (PA) accumulation. Present findings provide new insight into the molecular mechanisms underlying Cr toxicity in P. subcapitata.","Proteomic analysis of chromate-induced modifications in Pseudokirchneriella subcapitata Abs: In this work, we have analyzed the changes in the protein expression profile elicited by chromium (Cr) exposure in the freshwater green alga Pseudokirchneriella subcapitata, a well known bio-indicator of water pollution. We tested two experimental conditions, namely 0.2 and 1ppm of potassium dichromate; this concentration range includes the environmentally-relevant concentrations. Results show that neither concentration of potassium dichromate tested inhibited algal growth. However, the proteomic approach allowed the identification of relevant modifications in protein expression. In fact, among 800 protein spots detected by two-dimensional electrophoresis, 16 Cr-regulated proteins, including predicted and novel ones, were identified using tandem mass spectromic protein analysis. The results demonstrate a Cr-specific action in altering several photosynthetic proteins, such as ribulose-1,5-bisphosphate carboxylase/oxygenase (RuBisCO), RuBisCO activase, Light Harvesting Chla/b protein complex, and stress related Chla/b binding protein1. Although Cr toxicity with respect to photosynthesis has been already documented, here we have identified, for the first time, the target proteins of this toxicity. Cr also induced a modulation of some proteins involved in the metabolism of the amino acids glutamine, arginine and methionine. These data are supported by changes in cellular polyamine (PA) accumulation. Present findings provide new insight into the molecular mechanisms underlying Cr toxicity in P. subcapitata."
1234156,Zheng et al. 2009,A novel fluorescent distinguished probe for Cr (VI) in aqueous solution,"Salicylaldehyde rhodamine B hydrazone (SRBH) was developed as a new spectrofluorimetric probe for the selective and sensitive detection of CrO(4)(2-) in acidic conditions. The proposed method was based on the special oxidation reaction between non-fluorescent SRBH by potassium dichromate to produce a highly fluorescent rhodamine B, as a product. Under the optimum conditions described, the fluorescence enhancement at 591 nm was good linearly related to the concentration of CrO(4)(2-) from 1.0 x 10(-8) to 3.0 x 10(-7)M (0.42-12.6 ng mL(-1)) with a correlation coefficient of R(2)=0.9989 (n=10) and a detection limit of 1.5 x 10(-9)M (0.063 ng mL(-1)). The relative standard deviation (R.S.D.) was 2.0% (n=6). The proposed method was also successfully applied to the determination of chromium (VI) in drinking water, river water and synthetic samples.","A novel fluorescent distinguished probe for Cr (VI) in aqueous solution Abs: Salicylaldehyde rhodamine B hydrazone (SRBH) was developed as a new spectrofluorimetric probe for the selective and sensitive detection of CrO(4)(2-) in acidic conditions. The proposed method was based on the special oxidation reaction between non-fluorescent SRBH by potassium dichromate to produce a highly fluorescent rhodamine B, as a product. Under the optimum conditions described, the fluorescence enhancement at 591 nm was good linearly related to the concentration of CrO(4)(2-) from 1.0 x 10(-8) to 3.0 x 10(-7)M (0.42-12.6 ng mL(-1)) with a correlation coefficient of R(2)=0.9989 (n=10) and a detection limit of 1.5 x 10(-9)M (0.063 ng mL(-1)). The relative standard deviation (R.S.D.) was 2.0% (n=6). The proposed method was also successfully applied to the determination of chromium (VI) in drinking water, river water and synthetic samples."
1234155,Sharanabasappa et al. 2009,Mass attenuation coefficient of chromium and manganese compounds around absorption edge,"The total mass attenuation coefficient for Potassium dichromate, Potassium chromate and Manganese acetate compounds are measured at different photon energies 5.895, 6.404, 6.490, 7.058, 8.041 and 14.390 keV using Fe-55, Co-57 and 241Am source with Copper target, radioactive sources. The photon intensity is analyzed using a high resolution HPGe detector system coupled to MCA under good geometrical arrangement. The obtained values of mass attenuation coefficient values are compared with theoretical values. This study suggests that measured mass attenuation coefficient values at and near absorption edges differ from the theoretical value by about 5-28%.","Mass attenuation coefficient of chromium and manganese compounds around absorption edge Abs: The total mass attenuation coefficient for Potassium dichromate, Potassium chromate and Manganese acetate compounds are measured at different photon energies 5.895, 6.404, 6.490, 7.058, 8.041 and 14.390 keV using Fe-55, Co-57 and 241Am source with Copper target, radioactive sources. The photon intensity is analyzed using a high resolution HPGe detector system coupled to MCA under good geometrical arrangement. The obtained values of mass attenuation coefficient values are compared with theoretical values. This study suggests that measured mass attenuation coefficient values at and near absorption edges differ from the theoretical value by about 5-28%."
1234154,Chen et al. 2009,Distinct contributions of JNK and p38 to chromium cytotoxicity and inhibition of murine embryonic stem cell differentiation,"<strong>BACKGROUND: </strong>Potassium dichromate [Cr(VI)] is a widespread environmental toxicant responsible for increased risk of several human diseases. Cr(VI) exposure leads to activation of mitogen-activated protein kinases (MAPKs), including c-Jun N-terminal kinase (JNK)1/2, p38, and extracellular-signal regulated kinase (ERK)1/2.<br /><br /><strong>OBJECTIVES: </strong>We evaluated the contribution of MAPKs to Cr(VI) toxicity.<br /><br /><strong>METHODS: </strong>Phosphorylation of MAPKs and their downstream effectors was evaluated by Western immunoblotting; reactive oxygen species were measured by DCFDA (5',6'-chloromethyl-2'-7'-dichlorofluorescin diacetate) labeling and flow cytometry, and glutathione and glutathione disulfide levels were determined by monochrome graphic spectroflurometer. Cytotoxicity was assessed by the MTS [3-(4,5-dimethylthiazol-2-yl)-5-(3-carboxymethoxyphenyl)-2-(4-sulfophenyl)-2H-tetrazolium] assay and colony formation. Embryoid body (EB) differentiation was evaluated by contracting cardiomyocyte formation, and real-time polymerase chain reaction (RT-PCR) was used for cardiomyocyte-specific and stem-cell-specific gene expression.<br /><br /><strong>RESULTS: </strong>Acute treatment of mouse embryonic stem (ES) cells with 50 microM Cr(VI) induced the rapid phosphorylation of JNK, p38, and ERK and their respective downstream transcription factors, c-JUN, activating transcription factor-2, and ELK1. MAPK activation and cytotoxicity induction were partially blocked by pretreatment with the antioxidant N-acetyl cysteine. Ablation of the upstream MAP kinase kinase (MAP2K7) in ES cells prevented JNK activation, whereas ablation of MAP2K4 prevented both JNK and p38 activation. Using specific MAPK inhibitors and MAP2K4- and MAP2K7-deficient ES cells, we showed that JNK reduced acute Cr(VI) cytotoxicity, p38 potentiated it, and ERK had no effect. At low submicromolar concentrations, Cr(VI) caused MAP2K4/7-dependent JNK activation and MAP2K4-dependent p38 activation and strongly inhibited contracting cardiomyocyte development in wild-type ES cells, but much less so in Map2k7((-/-)) cells.<br /><br /><strong>CONCLUSION: </strong>Each MAPK distinctly contributes to chromium toxicity. Whereas JNK prevents and p38 promotes acute cytotoxicity, JNK contributes to optimal inhibition of ES cell differentiation by chromium.","Distinct contributions of JNK and p38 to chromium cytotoxicity and inhibition of murine embryonic stem cell differentiation Abs: <strong>BACKGROUND: </strong>Potassium dichromate [Cr(VI)] is a widespread environmental toxicant responsible for increased risk of several human diseases. Cr(VI) exposure leads to activation of mitogen-activated protein kinases (MAPKs), including c-Jun N-terminal kinase (JNK)1/2, p38, and extracellular-signal regulated kinase (ERK)1/2.<br /><br /><strong>OBJECTIVES: </strong>We evaluated the contribution of MAPKs to Cr(VI) toxicity.<br /><br /><strong>METHODS: </strong>Phosphorylation of MAPKs and their downstream effectors was evaluated by Western immunoblotting; reactive oxygen species were measured by DCFDA (5',6'-chloromethyl-2'-7'-dichlorofluorescin diacetate) labeling and flow cytometry, and glutathione and glutathione disulfide levels were determined by monochrome graphic spectroflurometer. Cytotoxicity was assessed by the MTS [3-(4,5-dimethylthiazol-2-yl)-5-(3-carboxymethoxyphenyl)-2-(4-sulfophenyl)-2H-tetrazolium] assay and colony formation. Embryoid body (EB) differentiation was evaluated by contracting cardiomyocyte formation, and real-time polymerase chain reaction (RT-PCR) was used for cardiomyocyte-specific and stem-cell-specific gene expression.<br /><br /><strong>RESULTS: </strong>Acute treatment of mouse embryonic stem (ES) cells with 50 microM Cr(VI) induced the rapid phosphorylation of JNK, p38, and ERK and their respective downstream transcription factors, c-JUN, activating transcription factor-2, and ELK1. MAPK activation and cytotoxicity induction were partially blocked by pretreatment with the antioxidant N-acetyl cysteine. Ablation of the upstream MAP kinase kinase (MAP2K7) in ES cells prevented JNK activation, whereas ablation of MAP2K4 prevented both JNK and p38 activation. Using specific MAPK inhibitors and MAP2K4- and MAP2K7-deficient ES cells, we showed that JNK reduced acute Cr(VI) cytotoxicity, p38 potentiated it, and ERK had no effect. At low submicromolar concentrations, Cr(VI) caused MAP2K4/7-dependent JNK activation and MAP2K4-dependent p38 activation and strongly inhibited contracting cardiomyocyte development in wild-type ES cells, but much less so in Map2k7((-/-)) cells.<br /><br /><strong>CONCLUSION: </strong>Each MAPK distinctly contributes to chromium toxicity. Whereas JNK prevents and p38 promotes acute cytotoxicity, JNK contributes to optimal inhibition of ES cell differentiation by chromium."
1234153,Brändli et al. 2009,Quantification of activated carbon contents in soils and sediments using chemothermal and wet oxidation methods,"Activated carbon (AC) strongly sorbs organic pollutants and can be used for remediation of soils and sediments. A method for AC quantification is essential to monitor AC (re)distribution. Since AC is black carbon (BC), two methods for BC quantification were tested for AC mixed in different soils and sediments: i) chemothermal oxidation (CTO) at a range of temperatures and ii) wet-chemical oxidation with a potassium dichromate/sulfuric acid solution. For three soils, the amount of AC was accurately determined by CTO at 375 degrees C. For two sediments, however, much of the AC disappeared during combustion at 375 degrees C, which could probably be explained by catalytic effects by sediment constituents. CTO at lower temperatures (325-350 degrees C) was a feasible alternative for one of the sediments. Wet oxidation effectively functioned for AC quantification in sediments, with almost complete AC recovery (81-92%) and low remaining amounts of native organic carbon (5-16%).","Quantification of activated carbon contents in soils and sediments using chemothermal and wet oxidation methods Abs: Activated carbon (AC) strongly sorbs organic pollutants and can be used for remediation of soils and sediments. A method for AC quantification is essential to monitor AC (re)distribution. Since AC is black carbon (BC), two methods for BC quantification were tested for AC mixed in different soils and sediments: i) chemothermal oxidation (CTO) at a range of temperatures and ii) wet-chemical oxidation with a potassium dichromate/sulfuric acid solution. For three soils, the amount of AC was accurately determined by CTO at 375 degrees C. For two sediments, however, much of the AC disappeared during combustion at 375 degrees C, which could probably be explained by catalytic effects by sediment constituents. CTO at lower temperatures (325-350 degrees C) was a feasible alternative for one of the sediments. Wet oxidation effectively functioned for AC quantification in sediments, with almost complete AC recovery (81-92%) and low remaining amounts of native organic carbon (5-16%)."
1234152,Nakamura et al. 2009,Molecular characterization of Cryptosporidium spp. from fecal samples of birds kept in captivity in Brazil,"The aim of this study was to determine the prevalence of Cryptosporidium species and genotypes in birds kept in captivity in Brazil. A total of 966 samples from 18 families of birds was collected and stored in 5% potassium dichromate solution at 4 degrees C until processing. Oocysts were purified in Sheather sugar solution following extraction of genomic DNA. Molecular analyses were performed using nested-PCR for amplification of fragments of the 18S subunit of rRNA gene and of the actin gene. Amplification of Cryptosporidium DNA fragments was obtained in 47 (4.86%) samples. Sequencing of amplified fragments and phylogenetic analyses allowed the identification of Cryptosporidium baileyi in a black vulture (Coragyps atratus), a domestic chicken (Gallus gallus domesticus) and a saffron finch (Sicalis flaveola); Cryptosporidium galli in canaries (Serinus canaria), a cockatiel (Nymphicus hollandicus) and lesser seed-finches (Oryzoborus angolensis); Cryptosporidium meleagridis in a domestic chicken (G. g. domesticus); Cryptosporidium parvum in a cockatiel (N. hollandicus); Cryptosporidium avian genotype I in a canary (S. canaria) and an Indian peafowl (Pavo cristatus); Cryptosporidium avian genotype II in ostriches (Struthio camelus) and Cryptosporidium avian genotype III in a cockatiel (N. hollandicus) and a peach-faced lovebird (Agapornis roseicolis).","Molecular characterization of Cryptosporidium spp. from fecal samples of birds kept in captivity in Brazil Abs: The aim of this study was to determine the prevalence of Cryptosporidium species and genotypes in birds kept in captivity in Brazil. A total of 966 samples from 18 families of birds was collected and stored in 5% potassium dichromate solution at 4 degrees C until processing. Oocysts were purified in Sheather sugar solution following extraction of genomic DNA. Molecular analyses were performed using nested-PCR for amplification of fragments of the 18S subunit of rRNA gene and of the actin gene. Amplification of Cryptosporidium DNA fragments was obtained in 47 (4.86%) samples. Sequencing of amplified fragments and phylogenetic analyses allowed the identification of Cryptosporidium baileyi in a black vulture (Coragyps atratus), a domestic chicken (Gallus gallus domesticus) and a saffron finch (Sicalis flaveola); Cryptosporidium galli in canaries (Serinus canaria), a cockatiel (Nymphicus hollandicus) and lesser seed-finches (Oryzoborus angolensis); Cryptosporidium meleagridis in a domestic chicken (G. g. domesticus); Cryptosporidium parvum in a cockatiel (N. hollandicus); Cryptosporidium avian genotype I in a canary (S. canaria) and an Indian peafowl (Pavo cristatus); Cryptosporidium avian genotype II in ostriches (Struthio camelus) and Cryptosporidium avian genotype III in a cockatiel (N. hollandicus) and a peach-faced lovebird (Agapornis roseicolis)."
1234151,Dickel et al. 2009,The strip patch test--indication in occupational dermatology demonstrated with a case history,"In occupational dermatology, repeat patch testing is a frequent occurrence when an expert opinion is required. As a result, discrepancies in test results may affect the legal position in respect of insurance and a reduction in the level of disability. The strip patch test (SPT) supports the diagnosis of allergic contact dermatitis when a weak sensitization is present or when a weak sensitizer with poor epidermal penetration is involved leading to a false-negative patch test result. We report on a 30-year-old man working as an industrial mechanic from 1995 to 2006. After approval of an occupational disease no. 5101 of the German ordinance on industrial disease in 2007, he went to court claiming compensation. The sensitization with clinical and occupational relevance to potassium dichromate that was decisive for the evaluation for insurance purposes was first confirmed in a patch test in 2005. Succeeding tests in 2006 in the context of an expert opinion and in 2008 in the context of our decisive expert opinion remained negative. We could reconfirm the potassium dichromate sensitization only by the SPT performed in the proposed standardized manner. The potassium dichromate allergy was the determining factor in the assessment for insurance purposes. This resulted in an adjustment in the severity of disability and a pension entitlement. From this case it is obvious that the detection of a SPT-positive and patch test-negative sensitization may have a significant impact on the situation with respect to the legal and insurance position.","The strip patch test--indication in occupational dermatology demonstrated with a case history Abs: In occupational dermatology, repeat patch testing is a frequent occurrence when an expert opinion is required. As a result, discrepancies in test results may affect the legal position in respect of insurance and a reduction in the level of disability. The strip patch test (SPT) supports the diagnosis of allergic contact dermatitis when a weak sensitization is present or when a weak sensitizer with poor epidermal penetration is involved leading to a false-negative patch test result. We report on a 30-year-old man working as an industrial mechanic from 1995 to 2006. After approval of an occupational disease no. 5101 of the German ordinance on industrial disease in 2007, he went to court claiming compensation. The sensitization with clinical and occupational relevance to potassium dichromate that was decisive for the evaluation for insurance purposes was first confirmed in a patch test in 2005. Succeeding tests in 2006 in the context of an expert opinion and in 2008 in the context of our decisive expert opinion remained negative. We could reconfirm the potassium dichromate sensitization only by the SPT performed in the proposed standardized manner. The potassium dichromate allergy was the determining factor in the assessment for insurance purposes. This resulted in an adjustment in the severity of disability and a pension entitlement. From this case it is obvious that the detection of a SPT-positive and patch test-negative sensitization may have a significant impact on the situation with respect to the legal and insurance position."
1234150,Banerjee et al. 2009,"Sorption of water vapor, hydration, and viscosity of carboxymethylhydroxypropyl guar, diutan, and xanthan gums, and their molecular association with and without salts (NaCl, CaCl2, HCOOK, CH3COONa, (NH4)2SO4 and MgSO4) in aqueous solution","Gums are routinely used in food industry, pharmacy and oil recovery process. In these uses, the hydrocolloids very often encounter interactions with salts at moderate to high temperature. Since they are normally employed in the form of solution and gel, their viscous or fluidity properties need detailed investigation. In the present work, properties such as water vapor adsorption of finely powdered carboxymethylhydroxypropyl derivatized guar (CMHPG) as well as xanthan (Xn) and diutan (Dn) gums, their hydration in solution, their viscosity behaviors, and salt effects on fluidity have been studied. The concentration domains for the existence of free and associated molecules in the studied solutions have been assessed from the viscosity results. The gums have been found to bind a fair amount of water from the vapor phase with them. In solution, they can interact and arrest a large amount of water in their folded configuration. Intrinsic viscosities of the gums in aqueous medium declined in the presence of salts. The activation energies for their viscous flow were moderate and comparable, and were dependent on their concentrations. From the power law relation and viscosity master curve behavior mostly two critical association states of the macromolecular dispersions were envisaged.","Sorption of water vapor, hydration, and viscosity of carboxymethylhydroxypropyl guar, diutan, and xanthan gums, and their molecular association with and without salts (NaCl, CaCl2, HCOOK, CH3COONa, (NH4)2SO4 and MgSO4) in aqueous solution Abs: Gums are routinely used in food industry, pharmacy and oil recovery process. In these uses, the hydrocolloids very often encounter interactions with salts at moderate to high temperature. Since they are normally employed in the form of solution and gel, their viscous or fluidity properties need detailed investigation. In the present work, properties such as water vapor adsorption of finely powdered carboxymethylhydroxypropyl derivatized guar (CMHPG) as well as xanthan (Xn) and diutan (Dn) gums, their hydration in solution, their viscosity behaviors, and salt effects on fluidity have been studied. The concentration domains for the existence of free and associated molecules in the studied solutions have been assessed from the viscosity results. The gums have been found to bind a fair amount of water from the vapor phase with them. In solution, they can interact and arrest a large amount of water in their folded configuration. Intrinsic viscosities of the gums in aqueous medium declined in the presence of salts. The activation energies for their viscous flow were moderate and comparable, and were dependent on their concentrations. From the power law relation and viscosity master curve behavior mostly two critical association states of the macromolecular dispersions were envisaged."
1234149,Yu et al. 2010,Effect of temperature on phytoextraction of hexavalent and trivalent chromium by hybrid willows,"The removal of hexavalent and trivalent chromium from hydroponic solution by plants to changes in temperature was investigated. Pre-rooted hybrid willows (Salix matsudana Koidz x alba L.) were exposed to a nutrient solution spiked with potassium chromate (K(2)CrO(4)) or chromium chloride (CrCl(3)) for 4 days. Ten different temperatures were tested ranging from 11 to 32 degrees C. Total Cr in solutions and in plant materials were all analyzed quantitatively. The results revealed that large amounts of the applied Cr were removed from the hydroponic solution in the presence of the plants. Significantly faster removal of Cr(III) than Cr(VI) was achieved by hybrid willows from the hydroponic solutions at all temperatures (P &lt; 0.01). The removal rates of both chemical forms of Cr by plants increased linearly with the increase of temperatures. The highest removal rate of Cr(VI) was found at 32 degrees C with a value of 1.99 microg Cr/g day, whereas the highest value of Cr(III) was 3.55 microg Cr/g day at the same temperature. Roots were the main sink for Cr accumulation in plants at all temperatures. Translocation of both chemical forms of Cr from roots to lower stems was only found at temperatures &gt; or = 24 degrees C. The temperature coefficient values (Q(10)) were 2.41 and 1.42 for Cr(VI) and Cr(III), respectively, indicating that the removal of Cr(VI) by hybrid willows was much more susceptible to changes in temperature than that of Cr(III). This information suggests that changes in temperature have a substantial influence on the uptake and accumulation of both chemical forms of Cr by plants.","Effect of temperature on phytoextraction of hexavalent and trivalent chromium by hybrid willows Abs: The removal of hexavalent and trivalent chromium from hydroponic solution by plants to changes in temperature was investigated. Pre-rooted hybrid willows (Salix matsudana Koidz x alba L.) were exposed to a nutrient solution spiked with potassium chromate (K(2)CrO(4)) or chromium chloride (CrCl(3)) for 4 days. Ten different temperatures were tested ranging from 11 to 32 degrees C. Total Cr in solutions and in plant materials were all analyzed quantitatively. The results revealed that large amounts of the applied Cr were removed from the hydroponic solution in the presence of the plants. Significantly faster removal of Cr(III) than Cr(VI) was achieved by hybrid willows from the hydroponic solutions at all temperatures (P &lt; 0.01). The removal rates of both chemical forms of Cr by plants increased linearly with the increase of temperatures. The highest removal rate of Cr(VI) was found at 32 degrees C with a value of 1.99 microg Cr/g day, whereas the highest value of Cr(III) was 3.55 microg Cr/g day at the same temperature. Roots were the main sink for Cr accumulation in plants at all temperatures. Translocation of both chemical forms of Cr from roots to lower stems was only found at temperatures &gt; or = 24 degrees C. The temperature coefficient values (Q(10)) were 2.41 and 1.42 for Cr(VI) and Cr(III), respectively, indicating that the removal of Cr(VI) by hybrid willows was much more susceptible to changes in temperature than that of Cr(III). This information suggests that changes in temperature have a substantial influence on the uptake and accumulation of both chemical forms of Cr by plants."
1234148,Zanetti et al. 2010,Evaluation of aging influence on renal toxicity caused by segment-specific nephrotoxicants of the proximal tubule in rat,"Little is known concerning the sensitivity of aged rats to xenobiotics inducing kidney damage. To increase this knowledge, the age-dependent response of the kidney to hexachloro-1 : 3-butadiene (HCBD) or potassium dichromate (chromate) was investigated. Rats were treated at different ages with a single dose of segment-specific nephrotoxicants of the proximal tubule, chosen on the basis of their specificity for S(3) and for S(1)-S(2) segments, respectively. The toxicological impact of these xenobiotics has been evaluated through biochemical and genomic markers, and histopathological investigation of kidney samples. HCBD treatment induced tubular necrosis of the S(3) segment of the proximal tubule associated with changes of toxicological markers unrelated to the age. In contrast, chromate treatment induced an increased kidney damage related to the rat age. In fact, histopathological investigation revealed that at 1 month of age tubular vacuolar degeneration was seen affecting S(1)-S(2) segments of the proximal tubule, whereas at 3 months of age tubular necrosis occurred in the same segments associated with tubular dilation of the distal portions. Consistently, biochemical analysis confirmed a direct correlation among genomic and biochemical marker variability and animal age. Altogether, the results show that during aging there is an increased sensitivity of kidney to chromate but not to HCBD-induced damage and evidence differential age-related selectivity of rats for nephrotoxic compounds. Significance for human risk assessment is discussed.","Evaluation of aging influence on renal toxicity caused by segment-specific nephrotoxicants of the proximal tubule in rat Abs: Little is known concerning the sensitivity of aged rats to xenobiotics inducing kidney damage. To increase this knowledge, the age-dependent response of the kidney to hexachloro-1 : 3-butadiene (HCBD) or potassium dichromate (chromate) was investigated. Rats were treated at different ages with a single dose of segment-specific nephrotoxicants of the proximal tubule, chosen on the basis of their specificity for S(3) and for S(1)-S(2) segments, respectively. The toxicological impact of these xenobiotics has been evaluated through biochemical and genomic markers, and histopathological investigation of kidney samples. HCBD treatment induced tubular necrosis of the S(3) segment of the proximal tubule associated with changes of toxicological markers unrelated to the age. In contrast, chromate treatment induced an increased kidney damage related to the rat age. In fact, histopathological investigation revealed that at 1 month of age tubular vacuolar degeneration was seen affecting S(1)-S(2) segments of the proximal tubule, whereas at 3 months of age tubular necrosis occurred in the same segments associated with tubular dilation of the distal portions. Consistently, biochemical analysis confirmed a direct correlation among genomic and biochemical marker variability and animal age. Altogether, the results show that during aging there is an increased sensitivity of kidney to chromate but not to HCBD-induced damage and evidence differential age-related selectivity of rats for nephrotoxic compounds. Significance for human risk assessment is discussed."
1234147,Arreola-Mendoza et al. 2009,The protective effect of alpha-tocopherol against dichromate-induced renal tight junction damage is mediated via ERK1/2,"Renal tight junctions (TJ) play a central role in modulating the paracellular pathway. We examined the function, quantity and distribution of TJ proteins: occludin and claudin-2 (cln-2), on proximal tubule in a model of acute renal failure (ARF) associated with oxidative damage. Since ERK1/2-p modulates TJ integrity, we studied their participation in dichromate (Cr(6+)) toxicity. We evaluated whether co-administration of the antioxidant alpha-tocopherol (alpha-TOC) prevents Cr(6+) toxicity in TJ. Female Wistar rats received potassium dichromate 15 mg/kg, s.c. (5.3 mg/kg of Cr(6+)) single dose, with or without alpha-TOC (125 mg/kg, p.o., daily). Two and 7 days after Cr(6+) treatment, oxidative damage was assessed by renal lipid peroxidation (LPO), proximal function was estimated by sodium and glucose fractional excretions. Occludin, cln-2, and ERK1/2-p were detected by immunofluorescence and Western blot. ARF induced by Cr(6+) provoked augment in the sodium and glucose urinary looses, increases in occludin quantity (6.6- and 15-fold on days 2 and 7, respectively) and the mislocation of cln-2. Electrophoresis migration showed a higher molecular weight band only in the Cr(6+)-administered groups, suggesting occludin hyperphosphorylation. Alpha-TOC treatment diminished the LPO, improved tubular function, and preserved TJ location and expression. In summary, we show disruption of occludin and cln-2 in ARF induced by Cr(6+)-intoxication. This study provides evidence of the beneficial effect of alpha-TOC on TJ structure and function undergoing oxidative damage, and we suggest the participation of ERK1/2 in the mechanisms leading to protection by the antioxidant.","The protective effect of alpha-tocopherol against dichromate-induced renal tight junction damage is mediated via ERK1/2 Abs: Renal tight junctions (TJ) play a central role in modulating the paracellular pathway. We examined the function, quantity and distribution of TJ proteins: occludin and claudin-2 (cln-2), on proximal tubule in a model of acute renal failure (ARF) associated with oxidative damage. Since ERK1/2-p modulates TJ integrity, we studied their participation in dichromate (Cr(6+)) toxicity. We evaluated whether co-administration of the antioxidant alpha-tocopherol (alpha-TOC) prevents Cr(6+) toxicity in TJ. Female Wistar rats received potassium dichromate 15 mg/kg, s.c. (5.3 mg/kg of Cr(6+)) single dose, with or without alpha-TOC (125 mg/kg, p.o., daily). Two and 7 days after Cr(6+) treatment, oxidative damage was assessed by renal lipid peroxidation (LPO), proximal function was estimated by sodium and glucose fractional excretions. Occludin, cln-2, and ERK1/2-p were detected by immunofluorescence and Western blot. ARF induced by Cr(6+) provoked augment in the sodium and glucose urinary looses, increases in occludin quantity (6.6- and 15-fold on days 2 and 7, respectively) and the mislocation of cln-2. Electrophoresis migration showed a higher molecular weight band only in the Cr(6+)-administered groups, suggesting occludin hyperphosphorylation. Alpha-TOC treatment diminished the LPO, improved tubular function, and preserved TJ location and expression. In summary, we show disruption of occludin and cln-2 in ARF induced by Cr(6+)-intoxication. This study provides evidence of the beneficial effect of alpha-TOC on TJ structure and function undergoing oxidative damage, and we suggest the participation of ERK1/2 in the mechanisms leading to protection by the antioxidant."
1234146,Raposo et al. 2009,An interlaboratory study as useful tool for proficiency testing of chemical oxygen demand measurements using solid substrates and liquid samples with high suspended solid content,"In 2008, the first Proficiency Testing Scheme of Chemical Oxygen Demand (1(st)COD-PT(ADG)) was conducted to assess the results obtained for different research groups whose field work is mainly anaerobic digestion. This study was performed using four samples, two solid samples as raw materials and two solid samples to prepare high concentration suspended solid solutions. Invitations were sent to a large number of laboratories, mainly to anaerobic digestion research groups. Finally, thirty labs from sixteen countries agreed to participate, but for different reasons four participants could not send any data. In total, twenty-six results were reported to the COD-PT coordinator. This study showed the importance of continuous participation in proficiency testing (PT) schemes in order to compare the results obtained. Taking into account the lack of a general standard method and high quality certified reference materials (CRMs), the traceability of COD determination is not currently easy to check. In addition, the spread of participants' results obtained was high and pointed to the advisability of using consensus values due to their unreliability. Therefore, the theoretical oxygen demand (ThOD) values were considered as assigned values for all the samples analysed. On the other hand, in this PT the established standard deviation (ESD) has been determined by the Horwitz modified function. Participants of this 1(st)COD-PT(ADG) were asked to give a short report on the analytical method used. Although all the participants used potassium dichromate as their oxidant reagent, their experimental procedures were very different. With the purpose of comparing the results obtained, the different experimental conditions used were classified into five methods, corresponding to two main categories, open and closed reflux. The performance of laboratories was expressed by the z-score, whose value is considered satisfactory when z-score &lt;or=+/-2. The overall analytical data evaluation showed that 64% of z-scores obtained were outside the accepted limits.","An interlaboratory study as useful tool for proficiency testing of chemical oxygen demand measurements using solid substrates and liquid samples with high suspended solid content Abs: In 2008, the first Proficiency Testing Scheme of Chemical Oxygen Demand (1(st)COD-PT(ADG)) was conducted to assess the results obtained for different research groups whose field work is mainly anaerobic digestion. This study was performed using four samples, two solid samples as raw materials and two solid samples to prepare high concentration suspended solid solutions. Invitations were sent to a large number of laboratories, mainly to anaerobic digestion research groups. Finally, thirty labs from sixteen countries agreed to participate, but for different reasons four participants could not send any data. In total, twenty-six results were reported to the COD-PT coordinator. This study showed the importance of continuous participation in proficiency testing (PT) schemes in order to compare the results obtained. Taking into account the lack of a general standard method and high quality certified reference materials (CRMs), the traceability of COD determination is not currently easy to check. In addition, the spread of participants' results obtained was high and pointed to the advisability of using consensus values due to their unreliability. Therefore, the theoretical oxygen demand (ThOD) values were considered as assigned values for all the samples analysed. On the other hand, in this PT the established standard deviation (ESD) has been determined by the Horwitz modified function. Participants of this 1(st)COD-PT(ADG) were asked to give a short report on the analytical method used. Although all the participants used potassium dichromate as their oxidant reagent, their experimental procedures were very different. With the purpose of comparing the results obtained, the different experimental conditions used were classified into five methods, corresponding to two main categories, open and closed reflux. The performance of laboratories was expressed by the z-score, whose value is considered satisfactory when z-score &lt;or=+/-2. The overall analytical data evaluation showed that 64% of z-scores obtained were outside the accepted limits."
1234144,Molina et al. 2009,Preliminary study on the use of a Teladorsagia circumcincta bulk milk ELISA test in dairy goats under experimental conditions,"An ELISA test for the detection of anti-Teladorsagia circumcincta antibodies in goat milk samples (both individual and bulk milk samples) has been developed in dairy goats experimentally infected with a trickle infection. The results observed were compared with those obtained when some other standard methods for the detection of animals infected with gastrointestinal nematodes (GIN), such as faecal egg counts (FEC) and serum pepsinogen levels. Some factors that could affect the final results of the test (dilution and nature of samples as well as their preservation at 4 degrees C for 0-10 days) were also monitored. The results show that the proposed test could allow the detection of infected herds using bulk milk samples. The levels of anti-T. circumcincta antibodies in milk and serum samples and the concentrations of serum pepsinogen showed a similar pattern over time. Refrigeration of milk samples for less than 5 days or its preservation with potassium dichromate for 10 days did not significantly affect the ability of the test to detect infected animals. Finally, when a commercial Ostertagia ostertagi ELISA kit was used to assay milk samples from goats infected with T. circumcincta, the results suggest that it may be possible to use a crude O. ostertagi antigen-based ELISA for the detection of goats infected with T. circumcincta.","Preliminary study on the use of a Teladorsagia circumcincta bulk milk ELISA test in dairy goats under experimental conditions Abs: An ELISA test for the detection of anti-Teladorsagia circumcincta antibodies in goat milk samples (both individual and bulk milk samples) has been developed in dairy goats experimentally infected with a trickle infection. The results observed were compared with those obtained when some other standard methods for the detection of animals infected with gastrointestinal nematodes (GIN), such as faecal egg counts (FEC) and serum pepsinogen levels. Some factors that could affect the final results of the test (dilution and nature of samples as well as their preservation at 4 degrees C for 0-10 days) were also monitored. The results show that the proposed test could allow the detection of infected herds using bulk milk samples. The levels of anti-T. circumcincta antibodies in milk and serum samples and the concentrations of serum pepsinogen showed a similar pattern over time. Refrigeration of milk samples for less than 5 days or its preservation with potassium dichromate for 10 days did not significantly affect the ability of the test to detect infected animals. Finally, when a commercial Ostertagia ostertagi ELISA kit was used to assay milk samples from goats infected with T. circumcincta, the results suggest that it may be possible to use a crude O. ostertagi antigen-based ELISA for the detection of goats infected with T. circumcincta."
1234143,Brito-Júnior et al. 2009,Sealing ability of MTA used as cervical barrier in intracoronal bleaching,"The aim of this study was to compare the sealing ability of white mineral trioxide aggregate (MTA) with that of other materials used as a cervical barrier during intracoronal bleaching. Thirty eight extracted teeth were endodontically treated and 3 mm of filling was removed to receive the barrier material: G1-Coltosol; G2 - Vidrion R; G3 - White MTA; G4-No barrier (negative control) and G5- Roots totally protected with three layers of cyanoacrylate (positive control). The 30% hydrogen peroxide associated with the sodium perborate was left in the pulp chamber for 24 h. The specimens were immersed in a test tube containing a solution of potassium chromate (yellow), which turns blue in the presence ofhydrogen peroxide. Two calibrated evaluators scored according to color in the presence of the detecting solution (0 - unaltered color, 1 - light blue and 2 - dark blue). Data were analyzed by the Kruskall-Wallis test (p&lt;0.05). The results showed no statistically significant differences between the experimental group G3 and positive control (G5). No statistically significant difference was observed between G1 and G3. However a statistical difference was verified between G2 and G3. MTA presented higher sealing ability than Vidrion R and did not differ from the positive control. However there was no difference between MTA and Coltosol.","Sealing ability of MTA used as cervical barrier in intracoronal bleaching Abs: The aim of this study was to compare the sealing ability of white mineral trioxide aggregate (MTA) with that of other materials used as a cervical barrier during intracoronal bleaching. Thirty eight extracted teeth were endodontically treated and 3 mm of filling was removed to receive the barrier material: G1-Coltosol; G2 - Vidrion R; G3 - White MTA; G4-No barrier (negative control) and G5- Roots totally protected with three layers of cyanoacrylate (positive control). The 30% hydrogen peroxide associated with the sodium perborate was left in the pulp chamber for 24 h. The specimens were immersed in a test tube containing a solution of potassium chromate (yellow), which turns blue in the presence ofhydrogen peroxide. Two calibrated evaluators scored according to color in the presence of the detecting solution (0 - unaltered color, 1 - light blue and 2 - dark blue). Data were analyzed by the Kruskall-Wallis test (p&lt;0.05). The results showed no statistically significant differences between the experimental group G3 and positive control (G5). No statistically significant difference was observed between G1 and G3. However a statistical difference was verified between G2 and G3. MTA presented higher sealing ability than Vidrion R and did not differ from the positive control. However there was no difference between MTA and Coltosol."
1234141,Soudani et al. 2010,Protective effects of Selenium (Se) on Chromium (VI) induced nephrotoxicity in adult rats,"Chromium is a toxic metal implicated in human diseases. This study was focused on investigating the possible protective effect of Se against K(2)Cr(2)O(7). Female Wistar rats, used in this study, were divided into four groups of six animals each: group I served as control which received standard diet; group II received orally only K(2)Cr(2)O(7) (700 ppm equivalent to 67 mg/kgbw); group III received both K(2)Cr(2)O(7) and Se (0.5 mg/kg of diet); group IV received Se (0.5mg Na(2)SeO(3)/kg of diet). The exposure of rats to K(2)Cr(2)O(7) for 21 days provoked renal damages with a significant increase in kidney malondialdehyde, superoxide dismutase, plasma creatinine, and uric acid levels, while catalase, glutathione peroxidase, non-protein thiol, Metallothionein and plasma urea levels decreased. Coadministration of Se in the diet of chromium-treated group improved malondialdehyde, renal biomarkers levels and antioxidant enzyme activities. Kidney histological studies confirmed biochemical parameters and the beneficial role of selenium.","Protective effects of Selenium (Se) on Chromium (VI) induced nephrotoxicity in adult rats Abs: Chromium is a toxic metal implicated in human diseases. This study was focused on investigating the possible protective effect of Se against K(2)Cr(2)O(7). Female Wistar rats, used in this study, were divided into four groups of six animals each: group I served as control which received standard diet; group II received orally only K(2)Cr(2)O(7) (700 ppm equivalent to 67 mg/kgbw); group III received both K(2)Cr(2)O(7) and Se (0.5 mg/kg of diet); group IV received Se (0.5mg Na(2)SeO(3)/kg of diet). The exposure of rats to K(2)Cr(2)O(7) for 21 days provoked renal damages with a significant increase in kidney malondialdehyde, superoxide dismutase, plasma creatinine, and uric acid levels, while catalase, glutathione peroxidase, non-protein thiol, Metallothionein and plasma urea levels decreased. Coadministration of Se in the diet of chromium-treated group improved malondialdehyde, renal biomarkers levels and antioxidant enzyme activities. Kidney histological studies confirmed biochemical parameters and the beneficial role of selenium."
1234140,Henning et al. 2009,Allergic contact dermatitis in Operation Iraqi Freedom: use of the T.R.U.E. Test in the combat environment,"<strong>BACKGROUND: </strong>Refractory dermatitis can frequently cause loss of personnel and poses an economic drain on the military due to the evacuation of civilians and soldiers out of theater.<br /><br /><strong>OBJECTIVE: </strong>Proof-of-concept retrospective analysis to review the utility of the T.R.U.E. Test in the combat environment.<br /><br /><strong>METHODS: </strong>Thirty T.R.U.E. Tests were performed by the dermatology clinic in Baghdad, Iraq, between January 15, 2008, and July 15, 2008. Thirty active-duty and civilian contractors referred to the dermatology clinic for dermatitis were tested and four others were clinically rechallenged for suspected bacitracin contact allergy.<br /><br /><strong>RESULTS: </strong>Of the 30 patients tested, 14 (46.7%) had a positive test reaction to at least one antigen. In these positive tests, nickel, neomycin, and thimersol each comprised 17% followed by neomycin, thimerosal, budesonide, epoxy resin, potassium dichromate, p-phenylenediamine, formaldehyde, quaternium-15, fragrance, and balsam of Peru. All four clinical rechallenges for bacitracin allergy were also positive.<br /><br /><strong>CONCLUSIONS: </strong>The use of the T.R.U.E. Test in the combat desert environment is an efficient, easy, and clinically relevant method of testing for allergic contact dermatitis. Continued study of the prevalence of allergic contact dermatitis at Ibn Sina Hospital, Baghdad, Iraq, is recommended.","Allergic contact dermatitis in Operation Iraqi Freedom: use of the T.R.U.E. Test in the combat environment Abs: <strong>BACKGROUND: </strong>Refractory dermatitis can frequently cause loss of personnel and poses an economic drain on the military due to the evacuation of civilians and soldiers out of theater.<br /><br /><strong>OBJECTIVE: </strong>Proof-of-concept retrospective analysis to review the utility of the T.R.U.E. Test in the combat environment.<br /><br /><strong>METHODS: </strong>Thirty T.R.U.E. Tests were performed by the dermatology clinic in Baghdad, Iraq, between January 15, 2008, and July 15, 2008. Thirty active-duty and civilian contractors referred to the dermatology clinic for dermatitis were tested and four others were clinically rechallenged for suspected bacitracin contact allergy.<br /><br /><strong>RESULTS: </strong>Of the 30 patients tested, 14 (46.7%) had a positive test reaction to at least one antigen. In these positive tests, nickel, neomycin, and thimersol each comprised 17% followed by neomycin, thimerosal, budesonide, epoxy resin, potassium dichromate, p-phenylenediamine, formaldehyde, quaternium-15, fragrance, and balsam of Peru. All four clinical rechallenges for bacitracin allergy were also positive.<br /><br /><strong>CONCLUSIONS: </strong>The use of the T.R.U.E. Test in the combat desert environment is an efficient, easy, and clinically relevant method of testing for allergic contact dermatitis. Continued study of the prevalence of allergic contact dermatitis at Ibn Sina Hospital, Baghdad, Iraq, is recommended."
1234139,Sarma and  Ghosh 2010,Clinico-allergological pattern of allergic contact dermatitis among 70 Indian children,"<strong>BACKGROUND: </strong>Rapid urbanization, westernization of lifestyles, poor quality of objects available and extremely relaxed vigilance on adherence to 'product safety guidelines' make any developing country like India highly susceptible to allergic contact dermatitis (ACD) even in children. There has been no previous attempts to assess the magnitude of childhood ACD in India.<br /><br /><strong>AIMS: </strong>To assess the clinico-allergological profile of ACD in Indian children.<br /><br /><strong>METHODS: </strong>All consecutive children up to 15 completed years of age who were patch tested over the last 3 years were analyzed from the records.<br /><br /><strong>RESULTS: </strong>A total of 70 children were studied (average age of disease onset 8.39+/-3.59 years [SD], range 1-15 years and average age of presentation 10.8 +/- 2.99 years [SD], range 5-15 years). Relevant allergy was noted in 48.6% of the patients. Age and sex had no significant role on the prevalence of ACD. Common allergens were paraben (43%), potassium dichromate (27%) and fragrance mix (26%). Most relevant allergens were potassium dichromate, paraben and fragrance. Foot was the most commonly involved site (25.7% of patients). Atopy was present in 18 patients (25.7%). A total of 22 irritant reactions were noted in 13 patients.<br /><br /><strong>CONCLUSION: </strong>This study reflects the current status of childhood ACD of this region.","Clinico-allergological pattern of allergic contact dermatitis among 70 Indian children Abs: <strong>BACKGROUND: </strong>Rapid urbanization, westernization of lifestyles, poor quality of objects available and extremely relaxed vigilance on adherence to 'product safety guidelines' make any developing country like India highly susceptible to allergic contact dermatitis (ACD) even in children. There has been no previous attempts to assess the magnitude of childhood ACD in India.<br /><br /><strong>AIMS: </strong>To assess the clinico-allergological profile of ACD in Indian children.<br /><br /><strong>METHODS: </strong>All consecutive children up to 15 completed years of age who were patch tested over the last 3 years were analyzed from the records.<br /><br /><strong>RESULTS: </strong>A total of 70 children were studied (average age of disease onset 8.39+/-3.59 years [SD], range 1-15 years and average age of presentation 10.8 +/- 2.99 years [SD], range 5-15 years). Relevant allergy was noted in 48.6% of the patients. Age and sex had no significant role on the prevalence of ACD. Common allergens were paraben (43%), potassium dichromate (27%) and fragrance mix (26%). Most relevant allergens were potassium dichromate, paraben and fragrance. Foot was the most commonly involved site (25.7% of patients). Atopy was present in 18 patients (25.7%). A total of 22 irritant reactions were noted in 13 patients.<br /><br /><strong>CONCLUSION: </strong>This study reflects the current status of childhood ACD of this region."
1234138,Coelho and  Rocha 2010,Assessment of the potential toxicity of a linear alkylbenzene sulfonate (LAS) to freshwater animal life by means of cladoceran bioassays,"The acute and chronic toxic effects of LAS on the cladocerans Daphnia similis, Ceriodaphnia dubia and Ceriodaphnia silvestrii were tested. Both types of toxicity bioassays and the methods of culture and stock maintenance of the test organisms conformed to the recommendations of ABNT (Brazilian Society of Technical Standards), which closely follow the standard methods of USEPA. The results obtained for EC(50) (48 h) were: 14.17 mg L(-1) for D. similis, 11.84 mg L(-1) for C. dubia and 13.52 mg L(-1) for C. silvestrii. In the chronic toxicity tests performed on C. dubia and C. silvestrii, there was a significant decrease in the fecundity of the exposed animals; the value of NOEC for C. dubia and C. silvestrii were 1.00 mg L(-1) and 2.50 mg L(-1), respectively. Cladoceran bioassays provided evidence that LAS concentration as low as 1.00 mg L(-1) can damage invertebrate animal life in freshwaters, concentrations that can be found in many eutrophic rivers and reservoirs.","Assessment of the potential toxicity of a linear alkylbenzene sulfonate (LAS) to freshwater animal life by means of cladoceran bioassays Abs: The acute and chronic toxic effects of LAS on the cladocerans Daphnia similis, Ceriodaphnia dubia and Ceriodaphnia silvestrii were tested. Both types of toxicity bioassays and the methods of culture and stock maintenance of the test organisms conformed to the recommendations of ABNT (Brazilian Society of Technical Standards), which closely follow the standard methods of USEPA. The results obtained for EC(50) (48 h) were: 14.17 mg L(-1) for D. similis, 11.84 mg L(-1) for C. dubia and 13.52 mg L(-1) for C. silvestrii. In the chronic toxicity tests performed on C. dubia and C. silvestrii, there was a significant decrease in the fecundity of the exposed animals; the value of NOEC for C. dubia and C. silvestrii were 1.00 mg L(-1) and 2.50 mg L(-1), respectively. Cladoceran bioassays provided evidence that LAS concentration as low as 1.00 mg L(-1) can damage invertebrate animal life in freshwaters, concentrations that can be found in many eutrophic rivers and reservoirs."
1234137,Sumiwi et al. 2010,The role of CD4+ T cells in the induction of contact hypersensitivity to mercury in a murine model,"<strong>BACKGROUND: </strong>The exact immunopathogenesis of contact hypersensitivity (CH) to mercury remains unclear.<br /><br /><strong>OBJECTIVE: </strong>The aim of the present study was to assess the role of CD4+ T cells in mercury-induced CH in mice.<br /><br /><strong>METHODS: </strong>Splenic CD4+ T cells obtained from nonsensitized and mercury-sensitized Balb/c mice were adoptively transferred to groups I and II of the syngeneic recipients, respectively. All recipients were ear-challenged with mercury. The next experiments were to transfer nonsensitized CD4+ T cells to group A of the recipients, whereas mercury-sensitized CD4+ T cells were transferred to groups B and C. Groups A and B were ear-challenged with mercury, whereas group C was ear-challenged with chromium. The ear swelling 24 hours and 48 hours after challenge was used to assess CH.<br /><br /><strong>RESULTS: </strong>The results of the present study showed that mercury-sensitized but not nonsensitized CD4+ T cells could transfer CH in mice. Furthermore, mercury-sensitized CD4+ T cells could transfer the induction of CH only in the recipients that were challenged with mercury, but not those that were challenged with chromium.<br /><br /><strong>CONCLUSION: </strong>The results of the present study suggest that mercury-induced CH may be mediated by mercury-specific CD4+ T cells.","The role of CD4+ T cells in the induction of contact hypersensitivity to mercury in a murine model Abs: <strong>BACKGROUND: </strong>The exact immunopathogenesis of contact hypersensitivity (CH) to mercury remains unclear.<br /><br /><strong>OBJECTIVE: </strong>The aim of the present study was to assess the role of CD4+ T cells in mercury-induced CH in mice.<br /><br /><strong>METHODS: </strong>Splenic CD4+ T cells obtained from nonsensitized and mercury-sensitized Balb/c mice were adoptively transferred to groups I and II of the syngeneic recipients, respectively. All recipients were ear-challenged with mercury. The next experiments were to transfer nonsensitized CD4+ T cells to group A of the recipients, whereas mercury-sensitized CD4+ T cells were transferred to groups B and C. Groups A and B were ear-challenged with mercury, whereas group C was ear-challenged with chromium. The ear swelling 24 hours and 48 hours after challenge was used to assess CH.<br /><br /><strong>RESULTS: </strong>The results of the present study showed that mercury-sensitized but not nonsensitized CD4+ T cells could transfer CH in mice. Furthermore, mercury-sensitized CD4+ T cells could transfer the induction of CH only in the recipients that were challenged with mercury, but not those that were challenged with chromium.<br /><br /><strong>CONCLUSION: </strong>The results of the present study suggest that mercury-induced CH may be mediated by mercury-specific CD4+ T cells."
1234135,Chiusolo et al. 2010,Kidney injury molecule-1 expression in rat proximal tubule after treatment with segment-specific nephrotoxicants: a tool for early screening of potential kidney toxicity,"Dose-response expression of kidney injury molecule-1 (KIM-1) gene in kidney cortex and its correlation with morphology and traditional biomarkers of nephrotoxicity (plasma creatinine and blood urea nitrogen, BUN) or segment-specific marker of proximal tubule injury (kidney glutamine synthetase, GSK) were studied in male rats treated with proximal tubule segment-specific nephrotoxicants. These included hexachloro-1:3-butadiene (HCBD, S(3) segment-specific), potassium dichromate (chromate, S(1)-S(2) segment-specific), and cephaloridine (Cph, S(2) segment-specific). Rats were treated with a single intraperitoneal (ip) injection of HCBD 25, 50, and 100 mg/kg, subcutaneous (sc) injection of chromate 8, 12.5, and 25 mg/kg; or ip injection of Cph 250, 500, and 1,000 mg/kg. KIM-1 gene showed a dose-dependent up-regulation induced by all segment-specific nephrotoxicants. Interestingly, magnitude of the up-regulation reflected the severity of microscopic tubular changes (degeneration, necrosis, and regeneration). Even low-severity microscopic observations were evidenced by significant gene expression changes. Furthermore, KIM-1 showed significant up-regulation even in the absence of morphological changes. In contrast, traditional and specific markers demonstrated low sensitivity or specificity. In conclusion, this study suggested KIM-1 as a sensitive molecular marker of different levels of tubular injury, and it is likely to represent a potential tool for early screening of nephrotoxicants.","Kidney injury molecule-1 expression in rat proximal tubule after treatment with segment-specific nephrotoxicants: a tool for early screening of potential kidney toxicity Abs: Dose-response expression of kidney injury molecule-1 (KIM-1) gene in kidney cortex and its correlation with morphology and traditional biomarkers of nephrotoxicity (plasma creatinine and blood urea nitrogen, BUN) or segment-specific marker of proximal tubule injury (kidney glutamine synthetase, GSK) were studied in male rats treated with proximal tubule segment-specific nephrotoxicants. These included hexachloro-1:3-butadiene (HCBD, S(3) segment-specific), potassium dichromate (chromate, S(1)-S(2) segment-specific), and cephaloridine (Cph, S(2) segment-specific). Rats were treated with a single intraperitoneal (ip) injection of HCBD 25, 50, and 100 mg/kg, subcutaneous (sc) injection of chromate 8, 12.5, and 25 mg/kg; or ip injection of Cph 250, 500, and 1,000 mg/kg. KIM-1 gene showed a dose-dependent up-regulation induced by all segment-specific nephrotoxicants. Interestingly, magnitude of the up-regulation reflected the severity of microscopic tubular changes (degeneration, necrosis, and regeneration). Even low-severity microscopic observations were evidenced by significant gene expression changes. Furthermore, KIM-1 showed significant up-regulation even in the absence of morphological changes. In contrast, traditional and specific markers demonstrated low sensitivity or specificity. In conclusion, this study suggested KIM-1 as a sensitive molecular marker of different levels of tubular injury, and it is likely to represent a potential tool for early screening of nephrotoxicants."
1234132,Williams et al. 2010,Coccidian oöcysts as type-specimens: long-term storage in aqueous potassium dichromate solution preserves DNA,"Preservation of the exogenous oöcyst stage of coccidian parasites (phylum Apicomplexa N.D. Levine, 1970) as type-specimens of newly described species has long been problematical. Conventional fixatives have proved unsatisfactory, and compromises such as embedding oöcysts in resin or photographing them are not entirely appropriate for various reasons. As an alternative, chilled potassium dichromate solution (normally used in the laboratory to prevent putrefaction of temporary preparations of live oöcysts) has been tested as a long-term preservative of sporulated oöcysts of Eimeria brunetti P.P. Levine, 1942, E. maxima Tyzzer, 1929, E. mitis Tyzzer, 1929, E. necatrix Johnson, 1930, E. praecox Johnson, 1930 and E. tenella (Railliet &amp; Lucet, 1891) (suborder Eimeriorina Léger, 1911; family Eimeriidae Minchin, 1903). Oöcysts from faeces of chickens Gallus gallus (Linnaeus) were placed in 2.5% w/v aqueous potassium dichromate solution (PDS) and stored in the dark at 4 +/- 2 degrees C. After 23 years in storage, oöcysts of each species were administered orally to chickens and failed to initiate infections, indicating that the oöcysts were dead. Nevertheless, after about 24 years, DNA was still recoverable from the oöcysts, and the original species identifications made by classic parasitological methods were confirmed by polymerase chain reaction assays. Furthermore, after almost 25 years, microscopical examination revealed that the walls and internal structures remained well preserved in 83-98% of the oöcysts of the six species investigated. Hence, PDS is potentially suitable for the long-term preservation of sporulated coccidian oöcysts as type-specimens for taxonomic purposes. The samples used in this study are now in the care of the Natural History Museum, London, UK. It is recommended that they be monitored in like manner, by suitably qualified scientists, at intervals of about 5 years to assess their state of preservation and the recoverability of DNA. Enough material is available to monitor it until it is at least 100 years old.","Coccidian oöcysts as type-specimens: long-term storage in aqueous potassium dichromate solution preserves DNA Abs: Preservation of the exogenous oöcyst stage of coccidian parasites (phylum Apicomplexa N.D. Levine, 1970) as type-specimens of newly described species has long been problematical. Conventional fixatives have proved unsatisfactory, and compromises such as embedding oöcysts in resin or photographing them are not entirely appropriate for various reasons. As an alternative, chilled potassium dichromate solution (normally used in the laboratory to prevent putrefaction of temporary preparations of live oöcysts) has been tested as a long-term preservative of sporulated oöcysts of Eimeria brunetti P.P. Levine, 1942, E. maxima Tyzzer, 1929, E. mitis Tyzzer, 1929, E. necatrix Johnson, 1930, E. praecox Johnson, 1930 and E. tenella (Railliet &amp; Lucet, 1891) (suborder Eimeriorina Léger, 1911; family Eimeriidae Minchin, 1903). Oöcysts from faeces of chickens Gallus gallus (Linnaeus) were placed in 2.5% w/v aqueous potassium dichromate solution (PDS) and stored in the dark at 4 +/- 2 degrees C. After 23 years in storage, oöcysts of each species were administered orally to chickens and failed to initiate infections, indicating that the oöcysts were dead. Nevertheless, after about 24 years, DNA was still recoverable from the oöcysts, and the original species identifications made by classic parasitological methods were confirmed by polymerase chain reaction assays. Furthermore, after almost 25 years, microscopical examination revealed that the walls and internal structures remained well preserved in 83-98% of the oöcysts of the six species investigated. Hence, PDS is potentially suitable for the long-term preservation of sporulated coccidian oöcysts as type-specimens for taxonomic purposes. The samples used in this study are now in the care of the Natural History Museum, London, UK. It is recommended that they be monitored in like manner, by suitably qualified scientists, at intervals of about 5 years to assess their state of preservation and the recoverability of DNA. Enough material is available to monitor it until it is at least 100 years old."
1234131,da Silva et al. 2010,"Physical, epidemiological, and molecular evaluation of infection by Cryptosporidium galli in Passeriformes","Due to the scarcity of information related to the epidemiology of Cryptosporidium infection in passerine birds, this study aimed to determine the periodicity of fecal shedding of Cryptosporidium spp. oocysts, after natural infection, and its clinical signs, mortality, and molecular characterization. Four hundred eighty fecal samples were collected from 40 birds, including 372 samples from 31 adult birds and 108 samples from nine young birds (up to 12 months old), housed in five aviaries, monthly from September 2007 to September 2008, with the exception of April. The birds originated from aviaries in which the following species were raised: great-billed seed-finch (Oryzoborus maximiliani), lesser seed-finch (Oryzoborus angolensis), ultramarine grosbeak (Cyanocompsa brissonii), and rusty-collared seedeater (Sporophila collaris). The samples were preserved in 2.5% potassium dichromate at 4 degrees C until processing. The oocysts were purified by centrifugal flotation in Sheather's solution, followed by genomic DNA extraction and molecular characterization of oocysts using the nested polymerase chain reaction for amplification of fragments of the 18S subunit of rRNA gene. Intermittent shedding of oocysts was observed by positive amplification for Cryptosporidium spp. in 91 (24.5%) samples of adult birds and 14 (13%) of young birds. The sequencing of the amplified fragments enabled the identification of Cryptosporidium galli. Although all the aviaries had birds positive for C. galli, morbidity or mortality was observed in only one aviary and was associated with concomitant infection with Escherichia coli and Isospora sp.","Physical, epidemiological, and molecular evaluation of infection by Cryptosporidium galli in Passeriformes Abs: Due to the scarcity of information related to the epidemiology of Cryptosporidium infection in passerine birds, this study aimed to determine the periodicity of fecal shedding of Cryptosporidium spp. oocysts, after natural infection, and its clinical signs, mortality, and molecular characterization. Four hundred eighty fecal samples were collected from 40 birds, including 372 samples from 31 adult birds and 108 samples from nine young birds (up to 12 months old), housed in five aviaries, monthly from September 2007 to September 2008, with the exception of April. The birds originated from aviaries in which the following species were raised: great-billed seed-finch (Oryzoborus maximiliani), lesser seed-finch (Oryzoborus angolensis), ultramarine grosbeak (Cyanocompsa brissonii), and rusty-collared seedeater (Sporophila collaris). The samples were preserved in 2.5% potassium dichromate at 4 degrees C until processing. The oocysts were purified by centrifugal flotation in Sheather's solution, followed by genomic DNA extraction and molecular characterization of oocysts using the nested polymerase chain reaction for amplification of fragments of the 18S subunit of rRNA gene. Intermittent shedding of oocysts was observed by positive amplification for Cryptosporidium spp. in 91 (24.5%) samples of adult birds and 14 (13%) of young birds. The sequencing of the amplified fragments enabled the identification of Cryptosporidium galli. Although all the aviaries had birds positive for C. galli, morbidity or mortality was observed in only one aviary and was associated with concomitant infection with Escherichia coli and Isospora sp."
1234130,Zhang et al. 2010,Increased anatomical detail by in vitro MR microscopy with a modified Golgi impregnation method,"Golgi impregnation is unique in its ability to display the dendritic trees and axons of large numbers of individual neurons by histology. Here we apply magnetic resonance microscopy to visualize the neuroanatomy of animal models by combining histologic fixation chemistry with paramagnetic contrast agents. Although there is some differential uptake of the standard small-molecular-weight contrast agents by different tissue types, detailed discrimination of tissue architecture in MR images does not approach that of standard histology. Our modified Golgi impregnation method significantly increases anatomic detail in magnetic resonance microscopy images. Fixed mouse brains were treated with a solution containing a paramagnetic contrast agent (gadoteridol) and potassium dichromate. Results demonstrate a specific contrast enhancement likely due to diamagnetic hexavalent chromium undergoing tissue specific reduction to paramagnetic trivalent chromium. This new method dramatically improves neuroanatomical contrast compared to conventional fixation, displaying detail approximating that of histologic specimens at low (4x) magnification.","Increased anatomical detail by in vitro MR microscopy with a modified Golgi impregnation method Abs: Golgi impregnation is unique in its ability to display the dendritic trees and axons of large numbers of individual neurons by histology. Here we apply magnetic resonance microscopy to visualize the neuroanatomy of animal models by combining histologic fixation chemistry with paramagnetic contrast agents. Although there is some differential uptake of the standard small-molecular-weight contrast agents by different tissue types, detailed discrimination of tissue architecture in MR images does not approach that of standard histology. Our modified Golgi impregnation method significantly increases anatomic detail in magnetic resonance microscopy images. Fixed mouse brains were treated with a solution containing a paramagnetic contrast agent (gadoteridol) and potassium dichromate. Results demonstrate a specific contrast enhancement likely due to diamagnetic hexavalent chromium undergoing tissue specific reduction to paramagnetic trivalent chromium. This new method dramatically improves neuroanatomical contrast compared to conventional fixation, displaying detail approximating that of histologic specimens at low (4x) magnification."
1234129,Zhang et al. 2011,The interaction of chromium(VI) with urease in solution,"The interaction between K(2)Cr(2)O(7) and urease was investigated using fluorescence, UV-vis absorption, and circular dichroism (CD) spectroscopy. The experimental results showed that the fluorescence quenching of urease by K(2)Cr(2)O(7) was a result of the formation of K(2)Cr(2)O(7)-urease complex. The apparent binding constant K (A) between K(2)Cr(2)O(7) and urease at 295, 302, and 309 K were obtained to be 2.14?×?10(4), 1.96?×?10(4), and 1.92?×?10(4) L mol(-1), respectively. The thermodynamic parameters, ?H° and ?S° were estimated to be -5.90 kJ mol(-1), 43.67 J mol(-1) K(-1) according to the Van't Hoff equation. The electrostatic interaction played a major role in stabilizing the complex. The distance r between donor (urease) and acceptor (K(2)Cr(2)O(7)) was 5.08 nm. The effect of K(2)Cr(2)O(7) on the conformation of urease was analyzed using UV-vis absorption, CD, synchronous fluorescence spectroscopy, and three-dimensional fluorescence spectra, the environment around Trp and Tyr residues were altered.","The interaction of chromium(VI) with urease in solution Abs: The interaction between K(2)Cr(2)O(7) and urease was investigated using fluorescence, UV-vis absorption, and circular dichroism (CD) spectroscopy. The experimental results showed that the fluorescence quenching of urease by K(2)Cr(2)O(7) was a result of the formation of K(2)Cr(2)O(7)-urease complex. The apparent binding constant K (A) between K(2)Cr(2)O(7) and urease at 295, 302, and 309 K were obtained to be 2.14?×?10(4), 1.96?×?10(4), and 1.92?×?10(4) L mol(-1), respectively. The thermodynamic parameters, ?H° and ?S° were estimated to be -5.90 kJ mol(-1), 43.67 J mol(-1) K(-1) according to the Van't Hoff equation. The electrostatic interaction played a major role in stabilizing the complex. The distance r between donor (urease) and acceptor (K(2)Cr(2)O(7)) was 5.08 nm. The effect of K(2)Cr(2)O(7) on the conformation of urease was analyzed using UV-vis absorption, CD, synchronous fluorescence spectroscopy, and three-dimensional fluorescence spectra, the environment around Trp and Tyr residues were altered."
1234128,Freitas and  Rocha 2011,Acute toxicity tests with the tropical cladoceran Pseudosida ramosa: The importance of using native species as test organisms,"Cladocerans have long been used for toxicological assessments of a diverse range of substances. The use of cladocerans in toxicity tests has many advantages, such as their short life cycle, parthenogenetic reproduction (clones), and high sensitivity to toxicants, as well as the easy laboratory maintenance of cultures. The most commonly used cladoceran in ecotoxicological studies of aquatic environments is undoubtedly Daphnia magna. Standard methods using cladocerans as test organisms have been documented and adopted by major international organizations and regulatory agencies of many countries. However, today there is a growing need for improving test organisms and protocols to better reflect local species sensitivity or site-specific conditions. The present study aimed to assess the tropical species Pseudosida ramosa as a potential test organism for ecotoxicological purposes, by carrying out standard acute tests with six reference compounds. Based on the results obtained in the present study and in comparison with other cladocerans, it was found that P. ramosa was more sensitive than Daphnia magna, had a sensitivity similar to that of Daphnia similis, and was less sensitive compared to Ceriodaphnia dubia and C. silvestrii (Neotropical species), except for the salts, sodium chloride and potassium chloride. Also, when P. ramosa was compared with test organisms of other taxonomic groups, we observed that it was more sensitive than most of the others, from simple coelenterates to complex fish. Considering these results and the wide distribution of the cladoceran P. ramosa in tropical and subtropical regions, we suggest that this species can be adopted as a test organism, being a good substitute for the exotic daphnid D. magna, for monitoring of toxicants in freshwaters.","Acute toxicity tests with the tropical cladoceran Pseudosida ramosa: The importance of using native species as test organisms Abs: Cladocerans have long been used for toxicological assessments of a diverse range of substances. The use of cladocerans in toxicity tests has many advantages, such as their short life cycle, parthenogenetic reproduction (clones), and high sensitivity to toxicants, as well as the easy laboratory maintenance of cultures. The most commonly used cladoceran in ecotoxicological studies of aquatic environments is undoubtedly Daphnia magna. Standard methods using cladocerans as test organisms have been documented and adopted by major international organizations and regulatory agencies of many countries. However, today there is a growing need for improving test organisms and protocols to better reflect local species sensitivity or site-specific conditions. The present study aimed to assess the tropical species Pseudosida ramosa as a potential test organism for ecotoxicological purposes, by carrying out standard acute tests with six reference compounds. Based on the results obtained in the present study and in comparison with other cladocerans, it was found that P. ramosa was more sensitive than Daphnia magna, had a sensitivity similar to that of Daphnia similis, and was less sensitive compared to Ceriodaphnia dubia and C. silvestrii (Neotropical species), except for the salts, sodium chloride and potassium chloride. Also, when P. ramosa was compared with test organisms of other taxonomic groups, we observed that it was more sensitive than most of the others, from simple coelenterates to complex fish. Considering these results and the wide distribution of the cladoceran P. ramosa in tropical and subtropical regions, we suggest that this species can be adopted as a test organism, being a good substitute for the exotic daphnid D. magna, for monitoring of toxicants in freshwaters."
1234127,Yap 2010,"The pattern of allergic contact hand dermatitis at a tertiary skin clinic in Sarawak, Malaysia",,"The pattern of allergic contact hand dermatitis at a tertiary skin clinic in Sarawak, Malaysia Abs: "
1234126,Soudani et al. 2011,Effects of selenium on chromium (VI)-induced hepatotoxicity in adult rats,"Chromium, a major environmental pollutant, is known for its wide toxic manifestations. The present experiment pertains to the protective role of selenium (Se) against K(2)Cr(2)O(7)-induced hepatotoxicity. Female Wistar rats were divided into four groups of six each: group I served as controls which received standard diet; group II received in drinking water K(2)Cr(2)O(7) alone (700 ppm); group III received both K(2)Cr(2)O(7) and Se (0.5 Na(2)SeO(3) mg/kg of diet); group IV received Se (0.5 mg/kg of diet) for 3 weeks. Exposure of rats to chromium promoted oxidative stress with an increase in malondialdehyde (MDA) and a decrease in glutathione (GSH) levels. A decrease in glutathione peroxidase (GPx) and an increase in superoxide dismutase (SOD) and catalase (CAT) activities were observed. Se supplementation to the diet of group III improved all the parameters cited above. Yet, plasma transaminases (AST and ALT), lactate dehydrogenase (LDH) activities, cholesterol, triglycerides (TG) and low density lipoprotein-cholesterol (LDL-C) levels increased, while high density lipoprotein-cholesterol (HDL-C) decreased. Co-administration of Se to the diet of group III restored hepatic markers to near-normal values. The biochemical results confirmed the histopathological findings. Therefore, our investigation revealed that Se was effective in preventing K(2)Cr(2)O(7)-induced hepatotoxicity.","Effects of selenium on chromium (VI)-induced hepatotoxicity in adult rats Abs: Chromium, a major environmental pollutant, is known for its wide toxic manifestations. The present experiment pertains to the protective role of selenium (Se) against K(2)Cr(2)O(7)-induced hepatotoxicity. Female Wistar rats were divided into four groups of six each: group I served as controls which received standard diet; group II received in drinking water K(2)Cr(2)O(7) alone (700 ppm); group III received both K(2)Cr(2)O(7) and Se (0.5 Na(2)SeO(3) mg/kg of diet); group IV received Se (0.5 mg/kg of diet) for 3 weeks. Exposure of rats to chromium promoted oxidative stress with an increase in malondialdehyde (MDA) and a decrease in glutathione (GSH) levels. A decrease in glutathione peroxidase (GPx) and an increase in superoxide dismutase (SOD) and catalase (CAT) activities were observed. Se supplementation to the diet of group III improved all the parameters cited above. Yet, plasma transaminases (AST and ALT), lactate dehydrogenase (LDH) activities, cholesterol, triglycerides (TG) and low density lipoprotein-cholesterol (LDL-C) levels increased, while high density lipoprotein-cholesterol (HDL-C) decreased. Co-administration of Se to the diet of group III restored hepatic markers to near-normal values. The biochemical results confirmed the histopathological findings. Therefore, our investigation revealed that Se was effective in preventing K(2)Cr(2)O(7)-induced hepatotoxicity."
1234124,Landeck et al. 2010,Positive concomitant test reactions to allergens in the standard patch test series,"<strong>BACKGROUND: </strong>Patch testing is performed to evaluate suspected allergic contact dermatitis. Common wisdom suggests that various allergens cross-react but only a few larger studies have published confirmations of this. The purpose of our study was to identify significant correlations between positive test reactions in a screening series.<br /><br /><strong>METHODS: </strong>A total of 1235 patients undergoing patch testing to the Hermal standard series at the Massachusetts General Hospital, Contact Dermatitis Clinic between 1990 and 2006 were investigated.<br /><br /><strong>RESULTS: </strong>Two or more positive reactions were seen in 411 patients (33.3%). Sensitizations to eight pairs of allergens were found to have significant correlation (P &lt;or= 0.0001). A strong association was observed for cross reactions between formaldehyde and its releasers quaternium 15 and imidazolidinyl urea and between balsam of Peru and fragrance mix. Moreover, significant co-sensitization was identified for potassium dichromate and colophony. Three significant pairings in our study were associations between fragrances and metals. Our data confirm the previously published cross-reactions in the literature between fragrance components, and formaldehyde and formaldehyde-releasing preservatives. The increased numbers of patients with metal and fragrance sensitization can be considered as a random finding due to independent sensitization.<br /><br /><strong>CONCLUSION: </strong>Being aware of cross-reacting allergens is essential to success in resolving allergic dermatitis when counseling patients.","Positive concomitant test reactions to allergens in the standard patch test series Abs: <strong>BACKGROUND: </strong>Patch testing is performed to evaluate suspected allergic contact dermatitis. Common wisdom suggests that various allergens cross-react but only a few larger studies have published confirmations of this. The purpose of our study was to identify significant correlations between positive test reactions in a screening series.<br /><br /><strong>METHODS: </strong>A total of 1235 patients undergoing patch testing to the Hermal standard series at the Massachusetts General Hospital, Contact Dermatitis Clinic between 1990 and 2006 were investigated.<br /><br /><strong>RESULTS: </strong>Two or more positive reactions were seen in 411 patients (33.3%). Sensitizations to eight pairs of allergens were found to have significant correlation (P &lt;or= 0.0001). A strong association was observed for cross reactions between formaldehyde and its releasers quaternium 15 and imidazolidinyl urea and between balsam of Peru and fragrance mix. Moreover, significant co-sensitization was identified for potassium dichromate and colophony. Three significant pairings in our study were associations between fragrances and metals. Our data confirm the previously published cross-reactions in the literature between fragrance components, and formaldehyde and formaldehyde-releasing preservatives. The increased numbers of patients with metal and fragrance sensitization can be considered as a random finding due to independent sensitization.<br /><br /><strong>CONCLUSION: </strong>Being aware of cross-reacting allergens is essential to success in resolving allergic dermatitis when counseling patients."
1234123,Lim et al. 2010,A Case of Chromium Contact Dermatitis due to Exposure from a Golf Glove,"Chromium is a transition metal and has been shown to elicit contact dermatitis. Although leather products have been known to be the most significant source of chromium exposure these days, the majority of reports have been related to exposure from shoe products. We herein report a professional golfer who became allergic to golf gloves made of chromium-tanned leather. A 27-year-old woman golfer presented with recurrent, pruritic, erythematous plaques that had been occurring on both hands for several years. The lesions developed whenever she had worn golf gloves for an extended period of time, especially during tournament season. To identify the causative agent, patch tests were performed and the results demonstrated a strong positive reaction to potassium dichromate 0.5% and to her own glove. The amount of chromium in her golf glove was analyzed to be 308.91 ppm and based on this, a diagnosis of allergic contact dermatitis due to a chromium-tanned leather glove was made. She was treated with oral antihistamines combined with topical steroids and advised to wear chromium-free leather gloves. There has been no evidence of recurrence during a six month follow-up period.","A Case of Chromium Contact Dermatitis due to Exposure from a Golf Glove Abs: Chromium is a transition metal and has been shown to elicit contact dermatitis. Although leather products have been known to be the most significant source of chromium exposure these days, the majority of reports have been related to exposure from shoe products. We herein report a professional golfer who became allergic to golf gloves made of chromium-tanned leather. A 27-year-old woman golfer presented with recurrent, pruritic, erythematous plaques that had been occurring on both hands for several years. The lesions developed whenever she had worn golf gloves for an extended period of time, especially during tournament season. To identify the causative agent, patch tests were performed and the results demonstrated a strong positive reaction to potassium dichromate 0.5% and to her own glove. The amount of chromium in her golf glove was analyzed to be 308.91 ppm and based on this, a diagnosis of allergic contact dermatitis due to a chromium-tanned leather glove was made. She was treated with oral antihistamines combined with topical steroids and advised to wear chromium-free leather gloves. There has been no evidence of recurrence during a six month follow-up period."
1234122,Domingues et al. 2010,Biomarkers as a tool to assess effects of chromium (VI): comparison of responses in zebrafish early life stages and adults,"The present work aims to compare the sensitivity of embryos and adult zebrafish to chromium (VI) (as potassium dichromate) focusing on biomarkers (cholinesterase, glutathione S-transferase and lactate dehydrogenase) as endpoints. Zebrafish eggs showed less sensitivity to Cr (VI) (96 h-LC50=145.7 mg/L) than adults (96 h-LC50=39.4 mg/L) probably due to the protective action of the chorion. However, biomarkers were much more responsive in larvae than in adults and gave clear indications about Cr (VI) mode of action: it seems to be neurotoxic (inhibited cholinesterase), to inhibit glutathione S-transferase activity and to interfere with cellular metabolic activity (changes in lactate dehydrogenase activity) in larvae. In adults, only glutathione S-transferase was responsive, showing a clear inhibition. The responsiveness of the analyzed biomarkers in larvae reinforces the idea of the usefulness of early life stage assays in the assessment of chemicals effects. Moreover, early life stage assays also contributed with relevant information regarding anomalies in larvae development and behavior. Further research should focus on the use of biomarkers to assess long term effects which are ecologically more relevant.","Biomarkers as a tool to assess effects of chromium (VI): comparison of responses in zebrafish early life stages and adults Abs: The present work aims to compare the sensitivity of embryos and adult zebrafish to chromium (VI) (as potassium dichromate) focusing on biomarkers (cholinesterase, glutathione S-transferase and lactate dehydrogenase) as endpoints. Zebrafish eggs showed less sensitivity to Cr (VI) (96 h-LC50=145.7 mg/L) than adults (96 h-LC50=39.4 mg/L) probably due to the protective action of the chorion. However, biomarkers were much more responsive in larvae than in adults and gave clear indications about Cr (VI) mode of action: it seems to be neurotoxic (inhibited cholinesterase), to inhibit glutathione S-transferase activity and to interfere with cellular metabolic activity (changes in lactate dehydrogenase activity) in larvae. In adults, only glutathione S-transferase was responsive, showing a clear inhibition. The responsiveness of the analyzed biomarkers in larvae reinforces the idea of the usefulness of early life stage assays in the assessment of chemicals effects. Moreover, early life stage assays also contributed with relevant information regarding anomalies in larvae development and behavior. Further research should focus on the use of biomarkers to assess long term effects which are ecologically more relevant."
1234120,Holland et al. 2010,Chromate-induced sulfur starvation and mRNA mistranslation in yeast are linked in a common mechanism of Cr toxicity,"Toxicity of the environmental carcinogen chromate is known to involve sulfur starvation and also error-prone mRNA translation. Here we reconcile those facts using the yeast model. We demonstrate that: (i) cysteine and methionine starvation mimic Cr-induced translation errors, (ii) genetic suppression of S starvation suppresses Cr-induced mistranslation, and (iii) mistranslation requires cysteine and methionine biosynthesis. Therefore, Cr-induced S starvation is the cause of mRNA mistranslation. This establishes a single, novel pathway mediating the toxicity of chromate.","Chromate-induced sulfur starvation and mRNA mistranslation in yeast are linked in a common mechanism of Cr toxicity Abs: Toxicity of the environmental carcinogen chromate is known to involve sulfur starvation and also error-prone mRNA translation. Here we reconcile those facts using the yeast model. We demonstrate that: (i) cysteine and methionine starvation mimic Cr-induced translation errors, (ii) genetic suppression of S starvation suppresses Cr-induced mistranslation, and (iii) mistranslation requires cysteine and methionine biosynthesis. Therefore, Cr-induced S starvation is the cause of mRNA mistranslation. This establishes a single, novel pathway mediating the toxicity of chromate."
1234119,Achiorno et al. 2010,"Validation test with embryonic and larval stages of Chordodes nobilii (Gordiida, Nematomorpha): sensitivity to three reference toxicants","Chordodes nobilii is a parasite whose pre- and postparasitic stages are found in different types of freshwater bodies. Due to the peculiarities of its life cycle, it acts as a link between freshwater bodies and terrestrial ecosystems. There is little toxicological information on the group Gordiida. It is only known that embryos and larvae of C. nobilii are sensitive to glyphosate and malathion at relevant concentrations in the environment. On this basis, the aims of this study were to characterize the sensitivity of the pre-parasitic stages of C. nobilii to three reference toxicants: sodium dodecyl sulfate (SDS), cadmium chloride and potassium dichromate (Cr(6+)), and to validate a previous experimental protocol for ecotoxicological risk assessment. The protocol involved acute exposure of early embryonic stages and larvae to the three toxicants for 96 h and 48 h, respectively. Embryo development was inhibited only by Cr(6+) which presented a IC(50) of 0.71 mg Cr(6+)L(-1). The development of the eggs exposed to SDS and those exposed to cadmium chloride showed no differences as compared to that of controls. However, the infective capacity of larvae derived from the eggs exposed to the three toxicants was lower than that of controls. Larval survival was affected even at the lowest concentration of the three toxicants assayed. In relation to other freshwater organisms, C. nobilii can be characterized as an organism medium to highly sensitive to the toxicants tested.","Validation test with embryonic and larval stages of Chordodes nobilii (Gordiida, Nematomorpha): sensitivity to three reference toxicants Abs: Chordodes nobilii is a parasite whose pre- and postparasitic stages are found in different types of freshwater bodies. Due to the peculiarities of its life cycle, it acts as a link between freshwater bodies and terrestrial ecosystems. There is little toxicological information on the group Gordiida. It is only known that embryos and larvae of C. nobilii are sensitive to glyphosate and malathion at relevant concentrations in the environment. On this basis, the aims of this study were to characterize the sensitivity of the pre-parasitic stages of C. nobilii to three reference toxicants: sodium dodecyl sulfate (SDS), cadmium chloride and potassium dichromate (Cr(6+)), and to validate a previous experimental protocol for ecotoxicological risk assessment. The protocol involved acute exposure of early embryonic stages and larvae to the three toxicants for 96 h and 48 h, respectively. Embryo development was inhibited only by Cr(6+) which presented a IC(50) of 0.71 mg Cr(6+)L(-1). The development of the eggs exposed to SDS and those exposed to cadmium chloride showed no differences as compared to that of controls. However, the infective capacity of larvae derived from the eggs exposed to the three toxicants was lower than that of controls. Larval survival was affected even at the lowest concentration of the three toxicants assayed. In relation to other freshwater organisms, C. nobilii can be characterized as an organism medium to highly sensitive to the toxicants tested."
1234118,Bilcha et al. 2010,Patch testing and contact allergens in Ethiopia--results of 514 contact dermatitis patients using the European baseline series,"<strong>BACKGROUND: </strong>Patch testing is essential to diagnose allergic contact dermatitis. Dermatologists in many countries use a baseline (standard) series covering the major allergens responsible for allergic contact dermatitis in their population, with the addition of relevant allergens for the individual patient. However, a baseline series has not yet been developed for Ethiopia. Our objective in this study is to identify common contact allergens to form the basis of a future baseline series in Ethiopia.<br /><br /><strong>METHODOLOGY: </strong>We patch tested 514 subjects with dermatitis according to the recommended procedure using the European baseline series for 1 year.<br /><br /><strong>RESULTS: </strong>52.7% of the tested subjects showed positive reaction for at least one allergen tested. The top five contact allergens identified were nickel sulfate, fragrance mix I, cobalt chloride, p-tert-butylphenolformaldehyde (PTBP) resin and potassium dichromate. Positive reactions to nickel and PTBP were commoner in females. PTBP positivity was strongly associated with foot eczema. Positive test reactions were commoner in cement workers, notably to potassium dichromate, which was also a commoner allergen in patients presenting with hand dermatitis. There were no reactions to several allergens, including neomycin, benzocaine, budesonide, primin and quaternium-15.<br /><br /><strong>CONCLUSION: </strong>Comparable patch test results with other countries have been shown and the European baseline series can be used as a baseline series in Ethiopia with some modification.","Patch testing and contact allergens in Ethiopia--results of 514 contact dermatitis patients using the European baseline series Abs: <strong>BACKGROUND: </strong>Patch testing is essential to diagnose allergic contact dermatitis. Dermatologists in many countries use a baseline (standard) series covering the major allergens responsible for allergic contact dermatitis in their population, with the addition of relevant allergens for the individual patient. However, a baseline series has not yet been developed for Ethiopia. Our objective in this study is to identify common contact allergens to form the basis of a future baseline series in Ethiopia.<br /><br /><strong>METHODOLOGY: </strong>We patch tested 514 subjects with dermatitis according to the recommended procedure using the European baseline series for 1 year.<br /><br /><strong>RESULTS: </strong>52.7% of the tested subjects showed positive reaction for at least one allergen tested. The top five contact allergens identified were nickel sulfate, fragrance mix I, cobalt chloride, p-tert-butylphenolformaldehyde (PTBP) resin and potassium dichromate. Positive reactions to nickel and PTBP were commoner in females. PTBP positivity was strongly associated with foot eczema. Positive test reactions were commoner in cement workers, notably to potassium dichromate, which was also a commoner allergen in patients presenting with hand dermatitis. There were no reactions to several allergens, including neomycin, benzocaine, budesonide, primin and quaternium-15.<br /><br /><strong>CONCLUSION: </strong>Comparable patch test results with other countries have been shown and the European baseline series can be used as a baseline series in Ethiopia with some modification."
1234117,Ban et al. 2010,Simultaneous analysis of the local and systemic immune responses in mice to study the occupational asthma mechanisms induced by chromium and platinum,"As a result of industrial development, increased exposure to platinum and chromium compounds and the subsequent development of occupational asthma (OA) has been reported. Although specific IgE antibodies, an indicator of allergic asthma, against chromium and platinum have been detected in workers with OA, the immunopathological mechanisms involved in this disease are not fully understood. To better understand these complex mechanisms, the local and systemic immune responses were simultaneously analyzed in mice sensitized and challenged three, four, or five times with sodium hexachloroplatinate (Pt salt) and with potassium dichromate (Cr salt) via the respiratory route. Dinitrochlorobenzene (DNCB) and anhydride trimellitic (TMA) were included in this study as reference compounds that induce Th1 and Th2 responses respectively. All the compounds studied may provoke pulmonary sensitization. In the Pt salt-treated mice with a significant increase in local Th2 cytokine production, the increase in IgE and mucus production and in eosinophil number had a positive correlation with the number of challenges (r=0.942, 0.976, and 0.978 respectively), whereas in the Cr salt-treated mice with no local increase in Th2 cytokines, the increase in IgE production and eosinophil numbers had an inverse correlation with the number of challenges (r=-0.895 and -0.999 respectively). The Th2-dominated response induced by Pt salt was very close to that induced by TMA and may thrive after the fifth challenge, probably due to the constancy of the significant decrease in IFN-? level in the spleens. The results of the present work may increase our understanding of the immunopathological mechanisms of OA induced by platinum and chromium, and emphasize the advantage of simultaneously analyzing local and systemic immune response when studying respiratory allergy.","Simultaneous analysis of the local and systemic immune responses in mice to study the occupational asthma mechanisms induced by chromium and platinum Abs: As a result of industrial development, increased exposure to platinum and chromium compounds and the subsequent development of occupational asthma (OA) has been reported. Although specific IgE antibodies, an indicator of allergic asthma, against chromium and platinum have been detected in workers with OA, the immunopathological mechanisms involved in this disease are not fully understood. To better understand these complex mechanisms, the local and systemic immune responses were simultaneously analyzed in mice sensitized and challenged three, four, or five times with sodium hexachloroplatinate (Pt salt) and with potassium dichromate (Cr salt) via the respiratory route. Dinitrochlorobenzene (DNCB) and anhydride trimellitic (TMA) were included in this study as reference compounds that induce Th1 and Th2 responses respectively. All the compounds studied may provoke pulmonary sensitization. In the Pt salt-treated mice with a significant increase in local Th2 cytokine production, the increase in IgE and mucus production and in eosinophil number had a positive correlation with the number of challenges (r=0.942, 0.976, and 0.978 respectively), whereas in the Cr salt-treated mice with no local increase in Th2 cytokines, the increase in IgE production and eosinophil numbers had an inverse correlation with the number of challenges (r=-0.895 and -0.999 respectively). The Th2-dominated response induced by Pt salt was very close to that induced by TMA and may thrive after the fifth challenge, probably due to the constancy of the significant decrease in IFN-? level in the spleens. The results of the present work may increase our understanding of the immunopathological mechanisms of OA induced by platinum and chromium, and emphasize the advantage of simultaneously analyzing local and systemic immune response when studying respiratory allergy."
1234116,Carmona et al. 2011,Proposal of an in vivo comet assay using haemocytes of Drosophila melanogaster,"This study presents the first application of an in vivo alkaline comet assay using haemocytes of Drosophila melanogaster larvae. These cells, which play a role similar to that of mammalian blood, can be easily obtained and represent an overall exposure of the treated larvae. To validate the assay, we evaluated the response of these cells to three well-known mutagenic agents: ethyl methanesulfonate (EMS), potassium dichromate (PD), and gamma radiation (?-irradiation). Third-instar Drosophila larvae were exposed to different concentrations of EMS (1, 2, and 4 mM) and PD (0.5, 1, and 2.5 mM) and to different doses of ?-irradiation (2, 4, and 8 G?). Subsequently, haemolymph was extracted from the larvae, and haemocytes were isolated by centrifugation and used in the comet assay. Haemocytes exhibited a significant dose-related increase in DNA damage, indicating that these cells are clearly sensitive to the treatments. These results suggest that the proposed in vivo comet test, using larvae haemocytes of D. melanogaster, may be a useful in vivo assay for genotoxicity assessment.","Proposal of an in vivo comet assay using haemocytes of Drosophila melanogaster Abs: This study presents the first application of an in vivo alkaline comet assay using haemocytes of Drosophila melanogaster larvae. These cells, which play a role similar to that of mammalian blood, can be easily obtained and represent an overall exposure of the treated larvae. To validate the assay, we evaluated the response of these cells to three well-known mutagenic agents: ethyl methanesulfonate (EMS), potassium dichromate (PD), and gamma radiation (?-irradiation). Third-instar Drosophila larvae were exposed to different concentrations of EMS (1, 2, and 4 mM) and PD (0.5, 1, and 2.5 mM) and to different doses of ?-irradiation (2, 4, and 8 G?). Subsequently, haemolymph was extracted from the larvae, and haemocytes were isolated by centrifugation and used in the comet assay. Haemocytes exhibited a significant dose-related increase in DNA damage, indicating that these cells are clearly sensitive to the treatments. These results suggest that the proposed in vivo comet test, using larvae haemocytes of D. melanogaster, may be a useful in vivo assay for genotoxicity assessment."
1234113,Casadio et al. 2011,Electron energy loss spectroscopy elucidates the elusive darkening of zinc potassium chromate in Georges Seurat's A Sunday on La Grande Jatte--1884,"The color darkening of selected brushstrokes of Georges Seurat's A Sunday on La Grande Jatte--1884 was noted as early as 1892. Artificial aging of model systems containing zinc yellow (K(2)O·4ZnCrO(4)·3H(2)O) mixed with linseed oil successfully replicated the phenomena observed on La Grande Jatte. Electron energy loss spectroscopy measurements performed on the uppermost few microns of thin sections of the paint layers (obtained with focused ion beam milling) determined that samples which turned olive green (aged at 90% RH, with SO(2) and light) contain mostly the altered species Cr(III) and that the ochre-yellow coloration of specimens aged at 50% RH with SO(2) and light is due to the presence of dichromate ions (Cr (VI)). The altered species are only present in the first few microns of paint and are likely poorly crystalline, so that they eluded other types of bulk and surface measurements, but they create a substantial color alteration at the surface of the paint films. A similar phenomenon was confirmed on a sample from La Grande Jatte, where Cr(III) and Cr(VI) dichromate ions were detected in the ochre-colored, altered brushstrokes of zinc yellow. Laboratory simulations demonstrated that the equilibrium between chromate and dichromate ions is reversible within the paint film and that the orange dichromate ions can be transformed back into bright yellow chromates by exposure to highly alkaline gases.","Electron energy loss spectroscopy elucidates the elusive darkening of zinc potassium chromate in Georges Seurat's A Sunday on La Grande Jatte--1884 Abs: The color darkening of selected brushstrokes of Georges Seurat's A Sunday on La Grande Jatte--1884 was noted as early as 1892. Artificial aging of model systems containing zinc yellow (K(2)O·4ZnCrO(4)·3H(2)O) mixed with linseed oil successfully replicated the phenomena observed on La Grande Jatte. Electron energy loss spectroscopy measurements performed on the uppermost few microns of thin sections of the paint layers (obtained with focused ion beam milling) determined that samples which turned olive green (aged at 90% RH, with SO(2) and light) contain mostly the altered species Cr(III) and that the ochre-yellow coloration of specimens aged at 50% RH with SO(2) and light is due to the presence of dichromate ions (Cr (VI)). The altered species are only present in the first few microns of paint and are likely poorly crystalline, so that they eluded other types of bulk and surface measurements, but they create a substantial color alteration at the surface of the paint films. A similar phenomenon was confirmed on a sample from La Grande Jatte, where Cr(III) and Cr(VI) dichromate ions were detected in the ochre-colored, altered brushstrokes of zinc yellow. Laboratory simulations demonstrated that the equilibrium between chromate and dichromate ions is reversible within the paint film and that the orange dichromate ions can be transformed back into bright yellow chromates by exposure to highly alkaline gases."
1234107,Madsen et al. 2011,"Encapsulating contact allergens in liposomes, ethosomes, and polycaprolactone may affect their sensitizing properties","Attempts to improve formulation of topical products are a continuing process and the development of micro- and nanovesicular systems as well as polymeric microparticles has led to marketing of topical drugs and cosmetics using these technologies. Encapsulation of some well-known contact allergens in ethanolic liposomes have been reported to enhance allergenicity compared with the allergens in similar vehicles without liposomes. The present report includes data on more sensitization studies using the mouse local lymph node assay with three contact allergens encapsulated in different dermal drug-delivery systems: liposomes, ethosomes, and polycaprolactone particles. The results show that the drug-delivery systems are not sensitizers in themselves. Encapsulating the hydrophilic contact allergen potassium dichromate in all three drug-delivery systems did not affect the sensitizing capacity of potassium dichromate compared with control solutions. However, encapsulating the lipophilic contact allergen dinitrochlorobenzene (DNCB) in polycaprolactone reduced the sensitizing capacity to 1211 ± 449 compared with liposomes (7602 ± 2658) and in acetone:olive oil (4:1) (5633 ± 666). The same trend was observed for encapsulating isoeugenol in polycaprolactone (1100 ± 406) compared with a formulation in acetone:olive oil (4491 ± 819) and in liposomes (3668 ± 950). Further, the size of DNCB-loaded liposomes did not affect the sensitizing properties. These results suggest that modern dermal drug-delivery systems may in some cases magnify or decrease the sensitizing capacity of the encapsulated contact allergen.","Encapsulating contact allergens in liposomes, ethosomes, and polycaprolactone may affect their sensitizing properties Abs: Attempts to improve formulation of topical products are a continuing process and the development of micro- and nanovesicular systems as well as polymeric microparticles has led to marketing of topical drugs and cosmetics using these technologies. Encapsulation of some well-known contact allergens in ethanolic liposomes have been reported to enhance allergenicity compared with the allergens in similar vehicles without liposomes. The present report includes data on more sensitization studies using the mouse local lymph node assay with three contact allergens encapsulated in different dermal drug-delivery systems: liposomes, ethosomes, and polycaprolactone particles. The results show that the drug-delivery systems are not sensitizers in themselves. Encapsulating the hydrophilic contact allergen potassium dichromate in all three drug-delivery systems did not affect the sensitizing capacity of potassium dichromate compared with control solutions. However, encapsulating the lipophilic contact allergen dinitrochlorobenzene (DNCB) in polycaprolactone reduced the sensitizing capacity to 1211 ± 449 compared with liposomes (7602 ± 2658) and in acetone:olive oil (4:1) (5633 ± 666). The same trend was observed for encapsulating isoeugenol in polycaprolactone (1100 ± 406) compared with a formulation in acetone:olive oil (4491 ± 819) and in liposomes (3668 ± 950). Further, the size of DNCB-loaded liposomes did not affect the sensitizing properties. These results suggest that modern dermal drug-delivery systems may in some cases magnify or decrease the sensitizing capacity of the encapsulated contact allergen."
1234106,Torres-García et al. 2011,Integrative analysis of transcriptomic and proteomic data of Shewanella oneidensis: missing value imputation using temporal datasets,"Despite significant improvements in recent years, proteomic datasets currently available still suffer from large number of missing values. Integrative analyses based upon incomplete proteomic and transcriptomic datasets could seriously bias the biological interpretation. In this study, we applied a non-linear data-driven stochastic gradient boosted trees (GBT) model to impute missing proteomic values using a temporal transcriptomic and proteomic dataset of Shewanella oneidensis. In this dataset, genes' expression was measured after the cells were exposed to 1 mM potassium chromate for 5, 30, 60, and 90 min, while protein abundance was measured for 45 and 90 min. With the ultimate objective to impute protein values for experimentally undetected samples at 45 and 90 min, we applied a serial set of algorithms to capture relationships between temporal gene and protein expression. This work follows four main steps: (1) a quality control step for gene expression reliability, (2) mRNA imputation, (3) protein prediction, and (4) validation. Initially, an S control chart approach is performed on gene expression replicates to remove unwanted variability. Then, we focused on the missing measurements of gene expression through a nonlinear Smoothing Splines Curve Fitting. This method identifies temporal relationships among transcriptomic data at different time points and enables imputation of mRNA abundance at 45 min. After mRNA imputation was validated by biological constrains (i.e. operons), we used a data-driven GBT model to impute protein abundance for the proteins experimentally undetected in the 45 and 90 min samples, based on relevant predictors such as temporal mRNA gene expression data and cellular functional roles. The imputed protein values were validated using biological constraints such as operon and pathway information through a permutation test to investigate whether dispersion measures are indeed smaller for known biological groups than for any set of random genes. Finally, we demonstrated that such missing value imputation improved characterization of the temporal response of S. oneidensis to chromate.","Integrative analysis of transcriptomic and proteomic data of Shewanella oneidensis: missing value imputation using temporal datasets Abs: Despite significant improvements in recent years, proteomic datasets currently available still suffer from large number of missing values. Integrative analyses based upon incomplete proteomic and transcriptomic datasets could seriously bias the biological interpretation. In this study, we applied a non-linear data-driven stochastic gradient boosted trees (GBT) model to impute missing proteomic values using a temporal transcriptomic and proteomic dataset of Shewanella oneidensis. In this dataset, genes' expression was measured after the cells were exposed to 1 mM potassium chromate for 5, 30, 60, and 90 min, while protein abundance was measured for 45 and 90 min. With the ultimate objective to impute protein values for experimentally undetected samples at 45 and 90 min, we applied a serial set of algorithms to capture relationships between temporal gene and protein expression. This work follows four main steps: (1) a quality control step for gene expression reliability, (2) mRNA imputation, (3) protein prediction, and (4) validation. Initially, an S control chart approach is performed on gene expression replicates to remove unwanted variability. Then, we focused on the missing measurements of gene expression through a nonlinear Smoothing Splines Curve Fitting. This method identifies temporal relationships among transcriptomic data at different time points and enables imputation of mRNA abundance at 45 min. After mRNA imputation was validated by biological constrains (i.e. operons), we used a data-driven GBT model to impute protein abundance for the proteins experimentally undetected in the 45 and 90 min samples, based on relevant predictors such as temporal mRNA gene expression data and cellular functional roles. The imputed protein values were validated using biological constraints such as operon and pathway information through a permutation test to investigate whether dispersion measures are indeed smaller for known biological groups than for any set of random genes. Finally, we demonstrated that such missing value imputation improved characterization of the temporal response of S. oneidensis to chromate."
1234105,Sawicka et al. 2010,Baicalin inhibits free radicals processes initiated by chromium ions,,Baicalin inhibits free radicals processes initiated by chromium ions Abs: 
1234103,Monico et al. 2011,Degradation process of lead chromate in paintings by Vincent van Gogh studied by means of synchrotron X-ray spectromicroscopy and related methods. 1. Artificially aged model samples,"On several paintings by artists of the end of the 19th century and the beginning of the 20th Century a darkening of the original yellow areas, painted with the chrome yellow pigment (PbCrO(4), PbCrO(4)·xPbSO(4), or PbCrO(4)·xPbO) is observed. The most famous of these are the various Sunflowers paintings Vincent van Gogh made during his career. In the first part of this work, we attempt to elucidate the degradation process of chrome yellow by studying artificially aged model samples. In view of the very thin (1-3 ?m) alteration layers that are formed, high lateral resolution spectroscopic methods such as microscopic X-ray absorption near edge (?-XANES), X-ray fluorescence spectrometry (?-XRF), and electron energy loss spectrometry (EELS) were employed. Some of these use synchrotron radiation (SR). Additionally, microscopic SR X-ray diffraction (SR ?-XRD), ?-Raman, and mid-FTIR spectroscopy were employed to completely characterize the samples. The formation of Cr(III) compounds at the surface of the chrome yellow paint layers is particularly observed in one aged model sample taken from a historic paint tube (ca. 1914). About two-thirds of the chromium that is present at the surface has reduced from the hexavalent to the trivalent state. The EELS and ?-XANES spectra are consistent with the presence of Cr(2)O(3)·2H(2)O (viridian). Moreover, as demonstrated by ?-XANES, the presence of another Cr(III) compound, such as either Cr(2)(SO(4))(3)·H(2)O or (CH(3)CO(2))(7)Cr(3)(OH)(2) [chromium(III) acetate hydroxide], is likely.","Degradation process of lead chromate in paintings by Vincent van Gogh studied by means of synchrotron X-ray spectromicroscopy and related methods. 1. Artificially aged model samples Abs: On several paintings by artists of the end of the 19th century and the beginning of the 20th Century a darkening of the original yellow areas, painted with the chrome yellow pigment (PbCrO(4), PbCrO(4)·xPbSO(4), or PbCrO(4)·xPbO) is observed. The most famous of these are the various Sunflowers paintings Vincent van Gogh made during his career. In the first part of this work, we attempt to elucidate the degradation process of chrome yellow by studying artificially aged model samples. In view of the very thin (1-3 ?m) alteration layers that are formed, high lateral resolution spectroscopic methods such as microscopic X-ray absorption near edge (?-XANES), X-ray fluorescence spectrometry (?-XRF), and electron energy loss spectrometry (EELS) were employed. Some of these use synchrotron radiation (SR). Additionally, microscopic SR X-ray diffraction (SR ?-XRD), ?-Raman, and mid-FTIR spectroscopy were employed to completely characterize the samples. The formation of Cr(III) compounds at the surface of the chrome yellow paint layers is particularly observed in one aged model sample taken from a historic paint tube (ca. 1914). About two-thirds of the chromium that is present at the surface has reduced from the hexavalent to the trivalent state. The EELS and ?-XANES spectra are consistent with the presence of Cr(2)O(3)·2H(2)O (viridian). Moreover, as demonstrated by ?-XANES, the presence of another Cr(III) compound, such as either Cr(2)(SO(4))(3)·H(2)O or (CH(3)CO(2))(7)Cr(3)(OH)(2) [chromium(III) acetate hydroxide], is likely."
1234102,Monico et al. 2011,Degradation process of lead chromate in paintings by Vincent van Gogh studied by means of synchrotron X-ray spectromicroscopy and related methods. 2. Original paint layer samples,"The darkening of the original yellow areas painted with the chrome yellow pigment (PbCrO(4), PbCrO(4)·xPbSO(4), or PbCrO(4)·xPbO) is a phenomenon widely observed on several paintings by Vincent van Gogh, such as the famous different versions of Sunflowers. During our previous investigations on artificially aged model samples of lead chromate, we established for the first time that darkening of chrome yellow is caused by reduction of PbCrO(4) to Cr(2)O(3)·2H(2)O (viridian green), likely accompanied by the presence of another Cr(III) compound, such as either Cr(2)(SO(4))(3)·H(2)O or (CH(3)CO(2))(7)Cr(3)(OH)(2) [chromium(III) acetate hydroxide]. In the second part of this work, in order to demonstrate that this reduction phenomenon effectively takes place in real paintings, we study original paint samples from two paintings of V. van Gogh. As with the model samples, in view of the thin superficial alteration layers that are present, high lateral resolution spectroscopic methods that make use of synchrotron radiation (SR), such as microscopic X-ray absorption near edge (?-XANES) and X-ray fluorescence spectrometry (?-XRF) were employed. Additionally, ?-Raman and mid-FTIR analyses were carried out to completely characterize the samples. On both paint microsamples, the local presence of reduced Cr was demonstrated by means of ?-XANES point measurements. The presence of Cr(III) was revealed in specific areas, in some cases correlated to the presence of Ba(sulfate) and/or to that of aluminum silicate compounds.","Degradation process of lead chromate in paintings by Vincent van Gogh studied by means of synchrotron X-ray spectromicroscopy and related methods. 2. Original paint layer samples Abs: The darkening of the original yellow areas painted with the chrome yellow pigment (PbCrO(4), PbCrO(4)·xPbSO(4), or PbCrO(4)·xPbO) is a phenomenon widely observed on several paintings by Vincent van Gogh, such as the famous different versions of Sunflowers. During our previous investigations on artificially aged model samples of lead chromate, we established for the first time that darkening of chrome yellow is caused by reduction of PbCrO(4) to Cr(2)O(3)·2H(2)O (viridian green), likely accompanied by the presence of another Cr(III) compound, such as either Cr(2)(SO(4))(3)·H(2)O or (CH(3)CO(2))(7)Cr(3)(OH)(2) [chromium(III) acetate hydroxide]. In the second part of this work, in order to demonstrate that this reduction phenomenon effectively takes place in real paintings, we study original paint samples from two paintings of V. van Gogh. As with the model samples, in view of the thin superficial alteration layers that are present, high lateral resolution spectroscopic methods that make use of synchrotron radiation (SR), such as microscopic X-ray absorption near edge (?-XANES) and X-ray fluorescence spectrometry (?-XRF) were employed. Additionally, ?-Raman and mid-FTIR analyses were carried out to completely characterize the samples. On both paint microsamples, the local presence of reduced Cr was demonstrated by means of ?-XANES point measurements. The presence of Cr(III) was revealed in specific areas, in some cases correlated to the presence of Ba(sulfate) and/or to that of aluminum silicate compounds."
1234099,Giri and  Patel 2011,Toxicity and bioaccumulation potential of Cr (VI) and Hg (II) on differential concentration by Eichhornia crassipes in hydroponic culture,"In this work, the phytoremediation of Cr (VI) and Hg (II) ion from water by an aquatic plant Eichhornia crassipes has been studied. Plants were cultured in a double distillated water with modified Hoagland's nutrient solution at pH 6.8 supplemented with 0, 0.75, 1.50, 2.50, and 4 mg Cr/L as potassium dichromate (K(2)Cr(2)O(7)) and 0, 5, 10, 15, and 20 mg Hg/L as mercuric chloride (HgCl(2)). They were separately harvested after 3, 6 and 9 days. Plants treated with 4 mg/L of Cr (VI) accumulated the highest concentration of metal in roots (1.22 mg/g, dry weight) and shoots (0.24 mg/g, dry weight) after 9 days; while those treated with 20 mg/L of Hg (II) accumulated the highest concentration of metal in roots (4.22 mg/g, dry weight) and shoots (2.43 mg/g, dry weight) after 9 days. Eichhornia crassipes biomass was characterised using AAS, SEM and FTIR. The accumulation and relative growth of metal ions at different concentrations of chromium and mercury solution significantly increased (P&lt;0.05) with the passage of time. The maximum values of bio-concentration factor (BCF) for Cr (VI) and Hg (II) were found to be 413.33 and 502.40 L/kg respectively.","Toxicity and bioaccumulation potential of Cr (VI) and Hg (II) on differential concentration by Eichhornia crassipes in hydroponic culture Abs: In this work, the phytoremediation of Cr (VI) and Hg (II) ion from water by an aquatic plant Eichhornia crassipes has been studied. Plants were cultured in a double distillated water with modified Hoagland's nutrient solution at pH 6.8 supplemented with 0, 0.75, 1.50, 2.50, and 4 mg Cr/L as potassium dichromate (K(2)Cr(2)O(7)) and 0, 5, 10, 15, and 20 mg Hg/L as mercuric chloride (HgCl(2)). They were separately harvested after 3, 6 and 9 days. Plants treated with 4 mg/L of Cr (VI) accumulated the highest concentration of metal in roots (1.22 mg/g, dry weight) and shoots (0.24 mg/g, dry weight) after 9 days; while those treated with 20 mg/L of Hg (II) accumulated the highest concentration of metal in roots (4.22 mg/g, dry weight) and shoots (2.43 mg/g, dry weight) after 9 days. Eichhornia crassipes biomass was characterised using AAS, SEM and FTIR. The accumulation and relative growth of metal ions at different concentrations of chromium and mercury solution significantly increased (P&lt;0.05) with the passage of time. The maximum values of bio-concentration factor (BCF) for Cr (VI) and Hg (II) were found to be 413.33 and 502.40 L/kg respectively."
1234096,Spiga et al. 2011,Simultaneous Golgi-Cox and immunofluorescence using confocal microscopy,"Visualization of neuronal elements is of fundamental importance in modern neuroscience. Golgi-Cox impregnation is a widely employed method that provides detailed information about morphological characteristics of neurons, but none regarding their neurochemical features. Immunocytochemical procedures, on the other hand, can provide a high degree of biochemical specificity but poorer morphological details, in particular if compared to Golgi-Cox impregnation. Hence, the combined use of these two approaches is highly desirable, especially for confocal microscopy that can exploit the advantages of both methods simultaneously. Here we show an innovative procedure of perfusion and fixation of brain tissue, that allows, by applying Golgi-Cox impregnation and immunofluorescence in the same histological section, to obtain high-quality histological material, with a very simple and inexpensive method. This procedure is based on three simple fixation steps: (1) a paraformaldehyde perfusion followed by a standard post-fixation to stabilize the subsequent immunofluorescence reaction; (2) the classical Golgi-Cox impregnation and (3) an immunofluorescence reaction in previously impregnated material. This combination allows simultaneous visualization of (a) the structural details (Golgi-Cox impregnated neurons), (b) the antigens' characterization, (c) the anatomical interactions between discrete neuronal elements and (d) the 3D reconstruction and modeling. The method is easy to perform and can be reproducibly applied by small laboratories and expanded through the use of different antibodies. Overall, the method presented in this study offers an innovative and powerful approach to study the nervous system, especially by using confocal microscopy.","Simultaneous Golgi-Cox and immunofluorescence using confocal microscopy Abs: Visualization of neuronal elements is of fundamental importance in modern neuroscience. Golgi-Cox impregnation is a widely employed method that provides detailed information about morphological characteristics of neurons, but none regarding their neurochemical features. Immunocytochemical procedures, on the other hand, can provide a high degree of biochemical specificity but poorer morphological details, in particular if compared to Golgi-Cox impregnation. Hence, the combined use of these two approaches is highly desirable, especially for confocal microscopy that can exploit the advantages of both methods simultaneously. Here we show an innovative procedure of perfusion and fixation of brain tissue, that allows, by applying Golgi-Cox impregnation and immunofluorescence in the same histological section, to obtain high-quality histological material, with a very simple and inexpensive method. This procedure is based on three simple fixation steps: (1) a paraformaldehyde perfusion followed by a standard post-fixation to stabilize the subsequent immunofluorescence reaction; (2) the classical Golgi-Cox impregnation and (3) an immunofluorescence reaction in previously impregnated material. This combination allows simultaneous visualization of (a) the structural details (Golgi-Cox impregnated neurons), (b) the antigens' characterization, (c) the anatomical interactions between discrete neuronal elements and (d) the 3D reconstruction and modeling. The method is easy to perform and can be reproducibly applied by small laboratories and expanded through the use of different antibodies. Overall, the method presented in this study offers an innovative and powerful approach to study the nervous system, especially by using confocal microscopy."
1234095,Lacaze et al. 2011,"Linking genotoxic responses in Gammarus fossarum germ cells with reproduction impairment, using the Comet assay","Germ cells perform a unique and critical biological function: they pass down DNA that will be used for the development of the next generation. Thus there is an increasing need to understand how the adult exposure to genotoxicants could show negative impact on the offspring of aquatic organisms. Hence this work addresses the question of the consequences of germ cell DNA damage resulting from parental exposure on reproduction quality in the freshwater crustacean Gammarus fossarum, a high ecologically relevant species. Initially, the sensitivity response of mature oocytes and spermatozoa to two model genotoxicants, MMS and K(2)Cr(2)O(7) was compared by implementing the Comet assay after the exposure of these gammarids in the laboratory and after the exposure of caged organisms in the field. Spermatozoa appeared significantly more susceptible than the oocytes to genotoxicants whatever were the exposure conditions. Secondly, a significant correlation between the level of damage to the sperm DNA of exposed parents and the abnormality rate in embryos that had developed in non-contaminated water were demonstrated. Interestingly, this relationship bridges the biomarker response measured in germ cells at molecular level and its consequences at individual level for the subsequent generation. Moreover, reproduction defects were observed for a level of DNA damage exceeding a minimal threshold, which could have significant consequences for the population dynamics of this high ecologically relevant species.","Linking genotoxic responses in Gammarus fossarum germ cells with reproduction impairment, using the Comet assay Abs: Germ cells perform a unique and critical biological function: they pass down DNA that will be used for the development of the next generation. Thus there is an increasing need to understand how the adult exposure to genotoxicants could show negative impact on the offspring of aquatic organisms. Hence this work addresses the question of the consequences of germ cell DNA damage resulting from parental exposure on reproduction quality in the freshwater crustacean Gammarus fossarum, a high ecologically relevant species. Initially, the sensitivity response of mature oocytes and spermatozoa to two model genotoxicants, MMS and K(2)Cr(2)O(7) was compared by implementing the Comet assay after the exposure of these gammarids in the laboratory and after the exposure of caged organisms in the field. Spermatozoa appeared significantly more susceptible than the oocytes to genotoxicants whatever were the exposure conditions. Secondly, a significant correlation between the level of damage to the sperm DNA of exposed parents and the abnormality rate in embryos that had developed in non-contaminated water were demonstrated. Interestingly, this relationship bridges the biomarker response measured in germ cells at molecular level and its consequences at individual level for the subsequent generation. Moreover, reproduction defects were observed for a level of DNA damage exceeding a minimal threshold, which could have significant consequences for the population dynamics of this high ecologically relevant species."
1234094,Deb et al. ,Role of Carum copticum seeds in modulating chromium-induced toxicity on human bronchial epithelial cells and human peripheral blood lymphocytes,"Carum copticum seeds are well known for ailment of various diseases since ancient times. The present study pertains to investigate modulatory effects of methanolic extract of C. copticum seeds (MCE) against hexavalent chromium induced cytotoxicity, genotoxicity, apoptosis and oxidative stress on human bronchial epithelial cells (BEAS-2B) and isolated human peripheral blood lymphocyte (PBL) in vitro. Treatment of BEAS-2B and PBL with MCE prior to potassium dichromate (K(2)Cr(2)O(7)) treatment exhibited an increase in cell viability and decrease of DNA damage as compared to K(2)Cr(2)O(7) treatment alone, as evaluated by WST-8 and Comet assay respectively. Further, MCE administration 1h prior to graded doses of K(2)Cr(2)O(7) significantly decreased reactive oxygen species (ROS) level, increased the mitochondrial membrane potential, reduced apoptosis and caspase 3 activity. MCE also ameliorated K(2)Cr(2)O(7) induced decrease in superoxide dismutase (SOD), glutathione peroxidase (GPx) antioxidant enzyme levels in BEAS-2B and PBL cells accompanied by reduction in lipid peroxides with maximum effect at 50?g/ml. Thus, this study provides strong evidence to support the beneficial effect of MCE in preventing Cr(VI) induced toxicity in BEAS-2B and PBL cells.","Role of Carum copticum seeds in modulating chromium-induced toxicity on human bronchial epithelial cells and human peripheral blood lymphocytes Abs: Carum copticum seeds are well known for ailment of various diseases since ancient times. The present study pertains to investigate modulatory effects of methanolic extract of C. copticum seeds (MCE) against hexavalent chromium induced cytotoxicity, genotoxicity, apoptosis and oxidative stress on human bronchial epithelial cells (BEAS-2B) and isolated human peripheral blood lymphocyte (PBL) in vitro. Treatment of BEAS-2B and PBL with MCE prior to potassium dichromate (K(2)Cr(2)O(7)) treatment exhibited an increase in cell viability and decrease of DNA damage as compared to K(2)Cr(2)O(7) treatment alone, as evaluated by WST-8 and Comet assay respectively. Further, MCE administration 1h prior to graded doses of K(2)Cr(2)O(7) significantly decreased reactive oxygen species (ROS) level, increased the mitochondrial membrane potential, reduced apoptosis and caspase 3 activity. MCE also ameliorated K(2)Cr(2)O(7) induced decrease in superoxide dismutase (SOD), glutathione peroxidase (GPx) antioxidant enzyme levels in BEAS-2B and PBL cells accompanied by reduction in lipid peroxides with maximum effect at 50?g/ml. Thus, this study provides strong evidence to support the beneficial effect of MCE in preventing Cr(VI) induced toxicity in BEAS-2B and PBL cells."
1234091,Belloni Fortina et al. 2011,Contact sensitization in very young children,"<strong>BACKGROUND: </strong>Allergic contact dermatitis is an increasingly recognized clinical problem in children.<br /><br /><strong>OBJECTIVE: </strong>The aim of our study was to evaluate contact sensitization in patients younger than 3 years of age with suspected contact dermatitis.<br /><br /><strong>METHODS: </strong>During a 6-year period (2002-2008), 321 children underwent routine patch testing with a screening pediatric standard series of 30 allergens.<br /><br /><strong>RESULTS: </strong>Two hundred children (62.3%; 102 girls and 98 boys aged 3-36 months [mean age 27 + 5.6 months]) developed at least one positive reaction. The most frequent reactions were to nickel sulfate (26.8%), followed by potassium dichromate (9%), cocamidopropylbetaine (7.2%), cobalt chloride (6.2%), neomycin sulfate (5%), and methylchloroisothiazolinone/methylisothiazolinone (4.4%). The prevalence of contact sensitization was similar in children with (61.3%) and without (63%) atopic dermatitis.<br /><br /><strong>LIMITATIONS: </strong>The prevalence of contact sensitization in children younger than 3 years of age was not compared with the prevalence in older children.<br /><br /><strong>CONCLUSION: </strong>A high prevalence of contact sensitization was found in preschool children, even younger than 3 years of age. Patch testing should be considered in this age group when persistent dermatitis does not respond to conventional treatment.","Contact sensitization in very young children Abs: <strong>BACKGROUND: </strong>Allergic contact dermatitis is an increasingly recognized clinical problem in children.<br /><br /><strong>OBJECTIVE: </strong>The aim of our study was to evaluate contact sensitization in patients younger than 3 years of age with suspected contact dermatitis.<br /><br /><strong>METHODS: </strong>During a 6-year period (2002-2008), 321 children underwent routine patch testing with a screening pediatric standard series of 30 allergens.<br /><br /><strong>RESULTS: </strong>Two hundred children (62.3%; 102 girls and 98 boys aged 3-36 months [mean age 27 + 5.6 months]) developed at least one positive reaction. The most frequent reactions were to nickel sulfate (26.8%), followed by potassium dichromate (9%), cocamidopropylbetaine (7.2%), cobalt chloride (6.2%), neomycin sulfate (5%), and methylchloroisothiazolinone/methylisothiazolinone (4.4%). The prevalence of contact sensitization was similar in children with (61.3%) and without (63%) atopic dermatitis.<br /><br /><strong>LIMITATIONS: </strong>The prevalence of contact sensitization in children younger than 3 years of age was not compared with the prevalence in older children.<br /><br /><strong>CONCLUSION: </strong>A high prevalence of contact sensitization was found in preschool children, even younger than 3 years of age. Patch testing should be considered in this age group when persistent dermatitis does not respond to conventional treatment."
1234090,Soudani et al. 2011,Oxidative damage induced by chromium (VI) in rat erythrocytes: Protective effect of selenium,"Excess chromium (Cr) exposure is associated with various pathological conditions including hematological dysfunction. The generation of oxidative stress is one of the plausible mechanisms behind Cr-induced cellular deteriorations. The efficacy of selenium (Se) to combat Cr-induced oxidative damage in the erythrocytes of adult rats was investigated in the current study. Female Wistar rats were randomly divided into four groups of six each: group I served as controls which received standard diet, group II received in drinking water K(2)Cr(2)O(7) alone (700 ppm), group III received both K(2)Cr(2)O(7) and Se (0.5 Na(2)SeO(3) mg/kg of diet), and group IV received Se (0.5 mg/kg of diet) for 3 weeks. Rats exposed to K(2)Cr(2)O(7) showed an increase of malondialdehyde and protein carbonyl levels and a decrease of sulfhydryl content, glutathione, non-protein thiol, and vitamin C levels. A decrease of enzyme activities like catalase, glutathione peroxidase, and superoxide dismutase activities was also noted. Co-administration of Se with K(2)Cr(2)O(7) restored the parameters cited above to near-normal values. Therefore, our investigation revealed that Se was a useful element preventing K(2)Cr(2)O(7)-induced erythrocyte damages.","Oxidative damage induced by chromium (VI) in rat erythrocytes: Protective effect of selenium Abs: Excess chromium (Cr) exposure is associated with various pathological conditions including hematological dysfunction. The generation of oxidative stress is one of the plausible mechanisms behind Cr-induced cellular deteriorations. The efficacy of selenium (Se) to combat Cr-induced oxidative damage in the erythrocytes of adult rats was investigated in the current study. Female Wistar rats were randomly divided into four groups of six each: group I served as controls which received standard diet, group II received in drinking water K(2)Cr(2)O(7) alone (700 ppm), group III received both K(2)Cr(2)O(7) and Se (0.5 Na(2)SeO(3) mg/kg of diet), and group IV received Se (0.5 mg/kg of diet) for 3 weeks. Rats exposed to K(2)Cr(2)O(7) showed an increase of malondialdehyde and protein carbonyl levels and a decrease of sulfhydryl content, glutathione, non-protein thiol, and vitamin C levels. A decrease of enzyme activities like catalase, glutathione peroxidase, and superoxide dismutase activities was also noted. Co-administration of Se with K(2)Cr(2)O(7) restored the parameters cited above to near-normal values. Therefore, our investigation revealed that Se was a useful element preventing K(2)Cr(2)O(7)-induced erythrocyte damages."
1234089,Landeck et al. 2011,Contact sensitization pattern in 172 atopic subjects,"<strong>BACKGROUND: </strong>Some authors have claimed a decreased cell-mediated immunity among atopic individuals, which would lead to observations of decreased rates of allergic contact dermatitis (ACD).<br /><br /><strong>OBJECTIVES: </strong>The purpose of our study was to investigate contact sensitization patterns in atopic subjects compared with non-atopic subjects.<br /><br /><strong>METHODS: </strong>Patch test data for 1247 patients undergoing patch testing at Massachusetts General Hospital between 1990 and 2006 were reviewed. Using accepted criteria, 172 subjects were classified as atopic individuals (AIs), and 1075 were classified as non-atopic individuals (NAIs). Sensitization rates were compared between these two groups.<br /><br /><strong>RESULTS: </strong>Sensitization rates (65.0% and 57.4% in the AI and NAI groups, respectively) and average numbers of positive responses (1.5 and 1.2 in the AI and NAI groups, respectively) were higher in AIs. Leading allergens observed were similar for both groups. Sensitization to potassium dichromate and phenylmercuric acetate was significantly greater in the AI group. The most frequent diagnosis in both groups was ACD (41.9% and 45.5% in the AI and NAI groups, respectively). In addition, more NAIs who were employed in occupations with exposure to wet and/or irritant conditions had hand eczema (P &lt; 0.005).<br /><br /><strong>CONCLUSIONS: </strong>Atopic individuals were shown to be at least as likely to have ACD as NAIs. The most common sensitizers were similar in both groups, suggesting common sources of sensitization.","Contact sensitization pattern in 172 atopic subjects Abs: <strong>BACKGROUND: </strong>Some authors have claimed a decreased cell-mediated immunity among atopic individuals, which would lead to observations of decreased rates of allergic contact dermatitis (ACD).<br /><br /><strong>OBJECTIVES: </strong>The purpose of our study was to investigate contact sensitization patterns in atopic subjects compared with non-atopic subjects.<br /><br /><strong>METHODS: </strong>Patch test data for 1247 patients undergoing patch testing at Massachusetts General Hospital between 1990 and 2006 were reviewed. Using accepted criteria, 172 subjects were classified as atopic individuals (AIs), and 1075 were classified as non-atopic individuals (NAIs). Sensitization rates were compared between these two groups.<br /><br /><strong>RESULTS: </strong>Sensitization rates (65.0% and 57.4% in the AI and NAI groups, respectively) and average numbers of positive responses (1.5 and 1.2 in the AI and NAI groups, respectively) were higher in AIs. Leading allergens observed were similar for both groups. Sensitization to potassium dichromate and phenylmercuric acetate was significantly greater in the AI group. The most frequent diagnosis in both groups was ACD (41.9% and 45.5% in the AI and NAI groups, respectively). In addition, more NAIs who were employed in occupations with exposure to wet and/or irritant conditions had hand eczema (P &lt; 0.005).<br /><br /><strong>CONCLUSIONS: </strong>Atopic individuals were shown to be at least as likely to have ACD as NAIs. The most common sensitizers were similar in both groups, suggesting common sources of sensitization."
1234088,Kuljanac et al. 2011,Epicutaneous patch test results in children and adults with allergic contact dermatitis in Karlovac county: a retrospective survey,"The aim of the study was to evaluate the results of epicutaneous patch testing with a standard series of contact allergens in children suspected to have allergic contact dermatitis (ACD), and to compare the results of patch testing between children and adults. Clinical records of children defined as patients aged ?18 years and adults examined at Department of Dermatology and Venereology, Karlovac General Hospital, for suspicion of ACD during the 1994-2009 period were reviewed. Epicutaneous patch testing with a standard series of contact allergens, manufactured by the Institute of Immunology, Zagreb, Croatia, was performed in group 1 consisting of 412 children (274 female and 138 male, mean age 13.4 years, range 4-18 years) and group 2 consisting of 4440 adult patients (2918 female and 1522 male, mean age 40.3 years, range 19-81 years). The most common six allergens differed between the two groups. Adult subjects were divided into three age subgroups: 19-40 (n=1708), 41-60 (n=1570) and 61-81 (n=1162 subjects). The high sensitization rate in younger subgroup and lower sensitization rate in the oldest group compared to adult patient group as a whole was statistically significant (P&lt;0.05). In children, the most common positive reactions were recorded to nickel sulfate (25.4%), thimerosal (17.8%), cobalt chloride (11.6%), fragrance mix (8.9%), white mercury precipitate (6.2%), formaldehyde (4.7%) and other allergens (25.4%). In adult patients, positive reactions were most common to nickel sulfate (32.6%), cobalt chloride (10.8%), fragrance mix (9.0%), wood tars (7.1%), potassium dichromate (6.6%), balsam of Peru (5.1%) and other allergens (28.8%). The group of children included 179 (43.4%) atopic subjects (according to Hanifin and Rajka criteria) and 233 (56.6%) non-atopic subjects. There was no statistically significant between-group difference and no statistically significant difference in nickel sulfate, cobalt chloride, fragrance mix and balsam of Peru sensitization between children and adult patients. A higher sensitization rate in children versus adults was recorded for thimerosal, white mercury precipitate and formaldehyde. Less frequent sensitization in children versus adults was found for wood tars and potassium dichromate. It is concluded that pediatric ACD exists and is more common than previously recognized. Sensitization to allergens differs between children and adults.","Epicutaneous patch test results in children and adults with allergic contact dermatitis in Karlovac county: a retrospective survey Abs: The aim of the study was to evaluate the results of epicutaneous patch testing with a standard series of contact allergens in children suspected to have allergic contact dermatitis (ACD), and to compare the results of patch testing between children and adults. Clinical records of children defined as patients aged ?18 years and adults examined at Department of Dermatology and Venereology, Karlovac General Hospital, for suspicion of ACD during the 1994-2009 period were reviewed. Epicutaneous patch testing with a standard series of contact allergens, manufactured by the Institute of Immunology, Zagreb, Croatia, was performed in group 1 consisting of 412 children (274 female and 138 male, mean age 13.4 years, range 4-18 years) and group 2 consisting of 4440 adult patients (2918 female and 1522 male, mean age 40.3 years, range 19-81 years). The most common six allergens differed between the two groups. Adult subjects were divided into three age subgroups: 19-40 (n=1708), 41-60 (n=1570) and 61-81 (n=1162 subjects). The high sensitization rate in younger subgroup and lower sensitization rate in the oldest group compared to adult patient group as a whole was statistically significant (P&lt;0.05). In children, the most common positive reactions were recorded to nickel sulfate (25.4%), thimerosal (17.8%), cobalt chloride (11.6%), fragrance mix (8.9%), white mercury precipitate (6.2%), formaldehyde (4.7%) and other allergens (25.4%). In adult patients, positive reactions were most common to nickel sulfate (32.6%), cobalt chloride (10.8%), fragrance mix (9.0%), wood tars (7.1%), potassium dichromate (6.6%), balsam of Peru (5.1%) and other allergens (28.8%). The group of children included 179 (43.4%) atopic subjects (according to Hanifin and Rajka criteria) and 233 (56.6%) non-atopic subjects. There was no statistically significant between-group difference and no statistically significant difference in nickel sulfate, cobalt chloride, fragrance mix and balsam of Peru sensitization between children and adult patients. A higher sensitization rate in children versus adults was recorded for thimerosal, white mercury precipitate and formaldehyde. Less frequent sensitization in children versus adults was found for wood tars and potassium dichromate. It is concluded that pediatric ACD exists and is more common than previously recognized. Sensitization to allergens differs between children and adults."
1234086,Lindegardh et al. 2011,"Quantification of dihydroartemisinin, artesunate and artemisinin in human blood: overcoming the technical challenge of protecting the peroxide bridge","<strong>BACKGROUND: </strong>Quantification of artemisinin (ARN) and its derivatives in whole blood has hitherto been thought impossible.<br /><br /><strong>RESULTS: </strong>A LC-MS/MS method for the analysis of artesunate (ARS), its metabolite dihydroartemisinin (DHA) and artemisinin in human whole blood has been developed and successfully validated. The method includes stabilization of the blood matrix at the time of collection and at the time of analysis. Addition of potassium dichromate to the blood samples deactivated the Fe(2+) core in hemoglobin, while deferoxamine chelated Fe(3+) and prevented back conversion into Fe(2+). A pilot study showed that the blood:plasma ratio for ARS and DHA is approximately 0.75, indicating a significantly lower uptake in red blood cells than had previously been estimated using radiolabeled drug methodology.<br /><br /><strong>CONCLUSIONS: </strong>The developed LC-MS/MS assay is the first method available for quantification of ARN and its derivatives in blood and opens up new possibilities of studying these drugs inside infected red blood cells.","Quantification of dihydroartemisinin, artesunate and artemisinin in human blood: overcoming the technical challenge of protecting the peroxide bridge Abs: <strong>BACKGROUND: </strong>Quantification of artemisinin (ARN) and its derivatives in whole blood has hitherto been thought impossible.<br /><br /><strong>RESULTS: </strong>A LC-MS/MS method for the analysis of artesunate (ARS), its metabolite dihydroartemisinin (DHA) and artemisinin in human whole blood has been developed and successfully validated. The method includes stabilization of the blood matrix at the time of collection and at the time of analysis. Addition of potassium dichromate to the blood samples deactivated the Fe(2+) core in hemoglobin, while deferoxamine chelated Fe(3+) and prevented back conversion into Fe(2+). A pilot study showed that the blood:plasma ratio for ARS and DHA is approximately 0.75, indicating a significantly lower uptake in red blood cells than had previously been estimated using radiolabeled drug methodology.<br /><br /><strong>CONCLUSIONS: </strong>The developed LC-MS/MS assay is the first method available for quantification of ARN and its derivatives in blood and opens up new possibilities of studying these drugs inside infected red blood cells."
1234085,Gutierrez et al. 2012,Exposure to sublethal chromium and endosulfan alter the diel vertical migration (DVM) in freshwater zooplankton crustaceans,"Among zooplankton behaviors, diel migrations constitute one of the most effective predator avoidance strategy and confer metabolic and demographic advantages. We aim to examine whether sublethal concentrations of two widespread pollutants (a pesticide with endosulfan and chromium as potassium dichromate) alter the depth selection, vertical migration and grouping of five freshwater species: Argyrodiaptomus falcifer, Notodiaptomus conifer, Pseudosida variabilis, Ceriodaphnia dubia and Daphnia magna. In a series of experimental assays, performed with 150 cm length transparent tubes, we analyzed the ascents and descents movements through periods of 24 h. Among controls, the copepods showed a tendency to remain closest to the surface, however, N. conifer registered a downward movement of 18.14 cm between 06:00 and 12:00. The cladoceran P. variabilis occupied the deeper position (85 cm), C. dubia showed a tendency to hike to the surface at 06:00 (57.7 cm) descending to lower levels at 18:00. D. magna showed a constant movement of ascent between 00:00 and 18:00, making an average travel of 29.4 cm. When subjected to pollutants, these behaviors were altered. It is hypothesized that a reduction in swimming activity and disorientation would be the main cause of such alterations. The high sensitivity of this endpoint sugests it to be adecuate as a complement in future standard toxicity tests.","Exposure to sublethal chromium and endosulfan alter the diel vertical migration (DVM) in freshwater zooplankton crustaceans Abs: Among zooplankton behaviors, diel migrations constitute one of the most effective predator avoidance strategy and confer metabolic and demographic advantages. We aim to examine whether sublethal concentrations of two widespread pollutants (a pesticide with endosulfan and chromium as potassium dichromate) alter the depth selection, vertical migration and grouping of five freshwater species: Argyrodiaptomus falcifer, Notodiaptomus conifer, Pseudosida variabilis, Ceriodaphnia dubia and Daphnia magna. In a series of experimental assays, performed with 150 cm length transparent tubes, we analyzed the ascents and descents movements through periods of 24 h. Among controls, the copepods showed a tendency to remain closest to the surface, however, N. conifer registered a downward movement of 18.14 cm between 06:00 and 12:00. The cladoceran P. variabilis occupied the deeper position (85 cm), C. dubia showed a tendency to hike to the surface at 06:00 (57.7 cm) descending to lower levels at 18:00. D. magna showed a constant movement of ascent between 00:00 and 18:00, making an average travel of 29.4 cm. When subjected to pollutants, these behaviors were altered. It is hypothesized that a reduction in swimming activity and disorientation would be the main cause of such alterations. The high sensitivity of this endpoint sugests it to be adecuate as a complement in future standard toxicity tests."
1234084,Darling et al. 2012,Sole dermatitis in children: patch testing revisited,"Although dermatoses affecting the soles of the feet in children are regularly encountered in dermatology clinics, the relationship with allergic contact dermatitis affecting this part of the foot is not well established. The aim of this study was to evaluate the relevance of patch testing children with sole dermatoses. We reviewed the results of all patch tests performed in children (&lt;18?years) presenting with dermatoses involving the soles between 1997 and 2009 from our departmental patch test database. Forty-one children were identified: 27 children with an inflammatory dermatitis affecting the sole and 14 children with juvenile plantar dermatosis (JPD). Seventeen (41%) children had at least one clinically relevant positive patch test reaction. Rubber additives and potassium dichromate were the most frequent allergens identified. Forty-eight percent of children with inflammatory dermatitis affecting the sole and 29% of children with JPD had at least one relevant reaction. Of the children with relevant reactions, 76% had a personal or family history of atopy. Our results demonstrate the importance of patch testing children with dermatoses affecting the soles and indicate that a history of atopy or a diagnosis of JPD should not deter investigation.","Sole dermatitis in children: patch testing revisited Abs: Although dermatoses affecting the soles of the feet in children are regularly encountered in dermatology clinics, the relationship with allergic contact dermatitis affecting this part of the foot is not well established. The aim of this study was to evaluate the relevance of patch testing children with sole dermatoses. We reviewed the results of all patch tests performed in children (&lt;18?years) presenting with dermatoses involving the soles between 1997 and 2009 from our departmental patch test database. Forty-one children were identified: 27 children with an inflammatory dermatitis affecting the sole and 14 children with juvenile plantar dermatosis (JPD). Seventeen (41%) children had at least one clinically relevant positive patch test reaction. Rubber additives and potassium dichromate were the most frequent allergens identified. Forty-eight percent of children with inflammatory dermatitis affecting the sole and 29% of children with JPD had at least one relevant reaction. Of the children with relevant reactions, 76% had a personal or family history of atopy. Our results demonstrate the importance of patch testing children with dermatoses affecting the soles and indicate that a history of atopy or a diagnosis of JPD should not deter investigation."
1234082,De Vero et al. 2011,Evolution-based strategy to generate non-genetically modified organisms Saccharomyces cerevisiae strains impaired in sulfate assimilation pathway,"<strong>UNLABELLED: </strong>AIMs: An evolution-based strategy was designed to screen novel yeast strains impaired in sulfate assimilation. Specifically, molybdate and chromate resistance was used as selectable phenotype to select sulfate permease-deficient variants that unable to produce sulfites and hydrogen sulfide (H(2) S).<br /><br /><strong>METHODS AND RESULTS: </strong>Four Saccharomyces cerevisiae parent strains were induced to sporulate. After tetrad digestion, spore suspensions were observed under the microscope to monitor the conjugation of gametes. Then, the cell suspension was inoculated in tubes containing YPD medium supplemented with ammonium molybdate or potassium chromate. Forty-four resistant strains were obtained and then tested in microvinifications. Three strains with a low sulfite production (SO2 &lt; 10 mg l(-1)) and with an impaired H2S production in grape must without added sulfites were selected.<br /><br /><strong>CONCLUSIONS: </strong>Our strategy enabled the selection of improved yeasts with desired oenological characteristics. Particularly, resistance to toxic analogues of sulfate allowed us to detect strains that unable to assimilate sulfates.<br /><br /><strong>SIGNIFICANCE AND IMPACT OF THE STUDY: </strong>This strategy that combines the sexual recombination of spores and application of a specific selective pressure provides a rapid screening method to generate genetic variants and select improved wine yeast strains with an impaired metabolism regarding the production of sulfites and H2S.","Evolution-based strategy to generate non-genetically modified organisms Saccharomyces cerevisiae strains impaired in sulfate assimilation pathway Abs: <strong>UNLABELLED: </strong>AIMs: An evolution-based strategy was designed to screen novel yeast strains impaired in sulfate assimilation. Specifically, molybdate and chromate resistance was used as selectable phenotype to select sulfate permease-deficient variants that unable to produce sulfites and hydrogen sulfide (H(2) S).<br /><br /><strong>METHODS AND RESULTS: </strong>Four Saccharomyces cerevisiae parent strains were induced to sporulate. After tetrad digestion, spore suspensions were observed under the microscope to monitor the conjugation of gametes. Then, the cell suspension was inoculated in tubes containing YPD medium supplemented with ammonium molybdate or potassium chromate. Forty-four resistant strains were obtained and then tested in microvinifications. Three strains with a low sulfite production (SO2 &lt; 10 mg l(-1)) and with an impaired H2S production in grape must without added sulfites were selected.<br /><br /><strong>CONCLUSIONS: </strong>Our strategy enabled the selection of improved yeasts with desired oenological characteristics. Particularly, resistance to toxic analogues of sulfate allowed us to detect strains that unable to assimilate sulfates.<br /><br /><strong>SIGNIFICANCE AND IMPACT OF THE STUDY: </strong>This strategy that combines the sexual recombination of spores and application of a specific selective pressure provides a rapid screening method to generate genetic variants and select improved wine yeast strains with an impaired metabolism regarding the production of sulfites and H2S."
1234080,Roche et al. 2012,Structure and quantification of microvascularisation within mouse long bones: what and how should we measure?,"Bone marrow vascularisation is involved in both remodeling and hematopoïesis. Challenged mouse models often require imaging and quantitative assessment of blood vessels and bone cell activities for a better understanding of the role of the vascular system. In this study we compared images of mouse hind limb long bone vascularisation after infusion of either barium sulfate or lead chromate-loaded silicon. The images were then analyzed through histology as well as low-resolution and synchrotron-radiation microtomography. We show that barium sulfate infusion provides the best vessel images and furthermore, that it is compatible with staining procedures used in bone histomorphometry and CD31 immunohistochemistry. Bone marrow vascularisation displays large structural and spatial distribution heterogeneity, including large lobular clusters of sinusoids and an unexpectedly substantial amount of capillaries in the adipocytes-rich distal third of the tibia. For an unbiased assessment of bone vascular development/changes, these features must be taken into account. We describe the conditions under which the quantification of microvascularisation on histological sections of barium-infused long bones is reproducible, as applied to seven-month-old male C57/Bl6J and mixed CD1/129Sv/J mice, and we propose a nomenclature for the histological parameters measured. Finally, we validate our technique by studying the effect of ovariectomy on mouse tibial vascular density.","Structure and quantification of microvascularisation within mouse long bones: what and how should we measure? Abs: Bone marrow vascularisation is involved in both remodeling and hematopoïesis. Challenged mouse models often require imaging and quantitative assessment of blood vessels and bone cell activities for a better understanding of the role of the vascular system. In this study we compared images of mouse hind limb long bone vascularisation after infusion of either barium sulfate or lead chromate-loaded silicon. The images were then analyzed through histology as well as low-resolution and synchrotron-radiation microtomography. We show that barium sulfate infusion provides the best vessel images and furthermore, that it is compatible with staining procedures used in bone histomorphometry and CD31 immunohistochemistry. Bone marrow vascularisation displays large structural and spatial distribution heterogeneity, including large lobular clusters of sinusoids and an unexpectedly substantial amount of capillaries in the adipocytes-rich distal third of the tibia. For an unbiased assessment of bone vascular development/changes, these features must be taken into account. We describe the conditions under which the quantification of microvascularisation on histological sections of barium-infused long bones is reproducible, as applied to seven-month-old male C57/Bl6J and mixed CD1/129Sv/J mice, and we propose a nomenclature for the histological parameters measured. Finally, we validate our technique by studying the effect of ovariectomy on mouse tibial vascular density."
1234079,Goullé et al. 2012,Accidental potassium dichromate poisoning. Toxicokinetics of chromium by ICP-MS-CRC in biological fluids and in hair,"Intoxications by chromium (Cr) compounds are very life threatening and often lethal. After oral ingestion of 2 or 3g of hexavalent Cr (Cr(VI)), gastrointestinal injury, but also hepatic and renal failure, often occurs which each leads to a fatal outcome in most patients. Cellular toxicity is associated with mitochondrial and lysosomal injury by biologically Cr(VI) reactive intermediates and reactive oxygen species. After Cr(VI) has been absorbed, there is not much that can be done except to control the main complications as the treatment is only symptomatic. The biotransformation of Cr(VI) to Cr(III) reduces the toxicity because the trivalent form does not cross cellular membranes as rapidly. In fact, more than 80% of Cr(VI) is cleared in urine as Cr(III). We report the case of a 58-year-old male patient who was admitted to hospital after accidental oral ingestion of a 30 g/L potassium dichromate (the estimated amount of ingested Cr is about 3g). ICP-MS equipped with a collision/reaction cell (CRC) and validated methods were used to monitor plasma (P), red blood cells (RBCs), urine (U) and hair chromium. For urine the results were expressed per gram of creatinine. After 7 days in the intensive care unit, the patient was discharged without renal or liver failure. P, RBC and U were monitored during 49 days. During this period Cr decreased respectively from 2088 ?g/L to 5 ?g/L, 631 ?g/L to 129 ?g/L and 3512 ?g/g to 10 ?g/g. The half-life was much shorter in P than in RBC as the poison was more quickly cleared from the P than from the RBC, suggesting a cellular trapping of the metal. Hair was collected 2 months after the intoxication. We report a very rare case of survival after accidental Cr poisoning which has an extremely poor prognosis and usually leads to rapid death. For the first time, this toxicokinetic study highlights a sequestration of chromium in the RBC and probably in all the cells.","Accidental potassium dichromate poisoning. Toxicokinetics of chromium by ICP-MS-CRC in biological fluids and in hair Abs: Intoxications by chromium (Cr) compounds are very life threatening and often lethal. After oral ingestion of 2 or 3g of hexavalent Cr (Cr(VI)), gastrointestinal injury, but also hepatic and renal failure, often occurs which each leads to a fatal outcome in most patients. Cellular toxicity is associated with mitochondrial and lysosomal injury by biologically Cr(VI) reactive intermediates and reactive oxygen species. After Cr(VI) has been absorbed, there is not much that can be done except to control the main complications as the treatment is only symptomatic. The biotransformation of Cr(VI) to Cr(III) reduces the toxicity because the trivalent form does not cross cellular membranes as rapidly. In fact, more than 80% of Cr(VI) is cleared in urine as Cr(III). We report the case of a 58-year-old male patient who was admitted to hospital after accidental oral ingestion of a 30 g/L potassium dichromate (the estimated amount of ingested Cr is about 3g). ICP-MS equipped with a collision/reaction cell (CRC) and validated methods were used to monitor plasma (P), red blood cells (RBCs), urine (U) and hair chromium. For urine the results were expressed per gram of creatinine. After 7 days in the intensive care unit, the patient was discharged without renal or liver failure. P, RBC and U were monitored during 49 days. During this period Cr decreased respectively from 2088 ?g/L to 5 ?g/L, 631 ?g/L to 129 ?g/L and 3512 ?g/g to 10 ?g/g. The half-life was much shorter in P than in RBC as the poison was more quickly cleared from the P than from the RBC, suggesting a cellular trapping of the metal. Hair was collected 2 months after the intoxication. We report a very rare case of survival after accidental Cr poisoning which has an extremely poor prognosis and usually leads to rapid death. For the first time, this toxicokinetic study highlights a sequestration of chromium in the RBC and probably in all the cells."
1234078,Hashkes and  Sagi 2011,[Tefillin-related contact dermatitis],"We describe a 14 year-old male with a background of atopic dermatitis who developed a contact dermatitis reaction on the left arm to the leather straps of tefillin (phylacteries), a religious article worn by observant Jewish men from the age 13 years during most morning prayer services. Patch testing revealed contact allergy to potassium dichromate, a chemical involved in leather tanning. Placing the leather straps over clothing and later switching to potassium dichromate-free leather straps resolved the condition. It is important to recognize this uncommon phenomena in a population in which a large proportion regularly use this religious article.","[Tefillin-related contact dermatitis] Abs: We describe a 14 year-old male with a background of atopic dermatitis who developed a contact dermatitis reaction on the left arm to the leather straps of tefillin (phylacteries), a religious article worn by observant Jewish men from the age 13 years during most morning prayer services. Patch testing revealed contact allergy to potassium dichromate, a chemical involved in leather tanning. Placing the leather straps over clothing and later switching to potassium dichromate-free leather straps resolved the condition. It is important to recognize this uncommon phenomena in a population in which a large proportion regularly use this religious article."
1234077,Gutierrez et al. 2012,"Microcrustaceans escape behavior as an early bioindicator of copper, chromium and endosulfan toxicity","The purpose of this work was to experimentally analyze the impact of copper, chromium and a commercial pesticide with endosulfan on the escape behavior of two copepods (Notodiaptomus conifer, Argyrodiaptomus falcifer) and three cladocerans (Daphnia magna, Pseudosida variabilis and Ceriodaphnia dubia). The experimental assays were carried out using a novel hydraulic devise designed to mimic three-speed predator capture behavior. Two concentrations, one &quot;high&quot; and one &quot;low&quot;, were employed and the exposure time was 15 (±5) minutes. With two exceptions, the species exposed to heavy metals manifested higher ability to escape than controls. Both concentrations of the pesticide reduced the escape ability of cladocerans but copepods responded, in general, in a similar manner as for heavy metals. The immediate apparent advantage of low and early toxic effects is discussed and the high sensitivity of the escape behavior suggests that it could be a complementary endpoint to be used in future ecotoxicological tests.","Microcrustaceans escape behavior as an early bioindicator of copper, chromium and endosulfan toxicity Abs: The purpose of this work was to experimentally analyze the impact of copper, chromium and a commercial pesticide with endosulfan on the escape behavior of two copepods (Notodiaptomus conifer, Argyrodiaptomus falcifer) and three cladocerans (Daphnia magna, Pseudosida variabilis and Ceriodaphnia dubia). The experimental assays were carried out using a novel hydraulic devise designed to mimic three-speed predator capture behavior. Two concentrations, one &quot;high&quot; and one &quot;low&quot;, were employed and the exposure time was 15 (±5) minutes. With two exceptions, the species exposed to heavy metals manifested higher ability to escape than controls. Both concentrations of the pesticide reduced the escape ability of cladocerans but copepods responded, in general, in a similar manner as for heavy metals. The immediate apparent advantage of low and early toxic effects is discussed and the high sensitivity of the escape behavior suggests that it could be a complementary endpoint to be used in future ecotoxicological tests."
1234076,Song et al. 2012,Bacterial communities in sediments of the shallow Lake Dongping in China,"<strong>AIMS: </strong>The purpose of this study was to discuss how the environmental inputs and anthropogenic activities impact bacterial communities in the sediments of a shallow, eutrophic and temperate freshwater lake.<br /><br /><strong>METHODS AND RESULTS: </strong>Sediment cores were collected from Lake Dongping, located in Taian, Shandong, China. All samples were processed within 4 h of collection. Total nitrogen, total phosphorus (TP), total organic carbon, ammonium nitrogen and nitrate nitrogen content of samples were measured by Kjeldahl determination, sulphuric acid-perchloric acid digestion and molybdenum blue colorimetry, potassium dichromate titration, Nessler's reagent colorimetric and the phenol disulphonic acid colorimetric method, respectively. Seasonal and temporal diversity of sediment bacterial communities at six stations in Lake Dongping were investigated using molecular approaches (terminal restriction fragment length polymorphism and 16S rDNA clone libraries). Noticeable seasonal and temporal variations were observed in bacterial diversity and composition at all six stations. Sediment bacterial communities in Lake Dongping belonged to 16 phyla: Proteobacteria (including ?-Proteobacteria, ?-Proteobacteria, ?-Proteobacteria, ?-Proteobacteria, ?-Proteobacteria), Acidobacteria, Planctomycetes, Bacteroidetes, Firmicutes, Verrucomicrobia, Nitrospira, Chloroflexi, Gemmatimonadetes, Chlorobi, Cyanobacteria, Deferribacteres, Actinobacteria, OP8, Spirochaetes and OP11. Members of ?-, ?- and ?-Proteobacterial sequences were predominant in 11 of 12 clone libraries derived from sediment samples. Sediment samples collected at stations 1 and 4 in July had the greatest bacterial diversity while those collected at station 2 in October had the least diversity. TP concentration was significantly correlated with the distribution of bacterial communities.<br /><br /><strong>CONCLUSIONS: </strong>Our results suggested that different environmental nutrient inputs contribute to seasonal and temporal variations of chemical features and bacterial communities in sediments of Lake Dongping. TP concentration was significantly correlated with the distribution of bacterial communities.<br /><br /><strong>SIGNIFICANCE AND IMPACT OF THE STUDY: </strong>This study has an important implication for the optimization of integrated ecosystem assessment of shallow temperate freshwater lake and provides interesting information for the subsequent of the ecosystem.","Bacterial communities in sediments of the shallow Lake Dongping in China Abs: <strong>AIMS: </strong>The purpose of this study was to discuss how the environmental inputs and anthropogenic activities impact bacterial communities in the sediments of a shallow, eutrophic and temperate freshwater lake.<br /><br /><strong>METHODS AND RESULTS: </strong>Sediment cores were collected from Lake Dongping, located in Taian, Shandong, China. All samples were processed within 4 h of collection. Total nitrogen, total phosphorus (TP), total organic carbon, ammonium nitrogen and nitrate nitrogen content of samples were measured by Kjeldahl determination, sulphuric acid-perchloric acid digestion and molybdenum blue colorimetry, potassium dichromate titration, Nessler's reagent colorimetric and the phenol disulphonic acid colorimetric method, respectively. Seasonal and temporal diversity of sediment bacterial communities at six stations in Lake Dongping were investigated using molecular approaches (terminal restriction fragment length polymorphism and 16S rDNA clone libraries). Noticeable seasonal and temporal variations were observed in bacterial diversity and composition at all six stations. Sediment bacterial communities in Lake Dongping belonged to 16 phyla: Proteobacteria (including ?-Proteobacteria, ?-Proteobacteria, ?-Proteobacteria, ?-Proteobacteria, ?-Proteobacteria), Acidobacteria, Planctomycetes, Bacteroidetes, Firmicutes, Verrucomicrobia, Nitrospira, Chloroflexi, Gemmatimonadetes, Chlorobi, Cyanobacteria, Deferribacteres, Actinobacteria, OP8, Spirochaetes and OP11. Members of ?-, ?- and ?-Proteobacterial sequences were predominant in 11 of 12 clone libraries derived from sediment samples. Sediment samples collected at stations 1 and 4 in July had the greatest bacterial diversity while those collected at station 2 in October had the least diversity. TP concentration was significantly correlated with the distribution of bacterial communities.<br /><br /><strong>CONCLUSIONS: </strong>Our results suggested that different environmental nutrient inputs contribute to seasonal and temporal variations of chemical features and bacterial communities in sediments of Lake Dongping. TP concentration was significantly correlated with the distribution of bacterial communities.<br /><br /><strong>SIGNIFICANCE AND IMPACT OF THE STUDY: </strong>This study has an important implication for the optimization of integrated ecosystem assessment of shallow temperate freshwater lake and provides interesting information for the subsequent of the ecosystem."
1234075,Shin et al. 2012,Overlapping distribution of osteopontin and calcium in the ischemic core of rat brain after transient focal ischemia,"Osteopontin (OPN), an adhesive glycoprotein, has recently been proposed to act as an opsonin that facilitates phagocytosis of neuronal debris by macrophages in the ischemic brain. The present study was designed to elucidate the process whereby OPN binds to neuronal cell debris in a rat model of ischemic stroke. Significant co-localization of the OPN protein and calcium deposits in the ischemic core were observed by combining alizarin red staining and OPN immunohistochemistry. In addition, electron microscopy (EM) using the osmium/potassium dichromate method revealed that electron-dense precipitates, typical of calcium deposits, were localized mainly along the periphery of putative degenerating neurites. This topical pattern of calcium precipitates resembled the distribution of OPN as detected by immunogold-silver EM. Combining immunogold-silver EM and electron probe microanalysis further demonstrated that the OPN protein was localized at the periphery of cell debris or degenerating neurites, corresponding with locally higher concentrations of calcium and phosphorus, and that the relative magnitude of OPN accumulation was comparable to that of calcium and phosphorus. These data suggest that calcium precipitation provides a matrix for the binding of the OPN protein within the debris or degenerating neurites induced by ischemic injury. Therefore, OPN binding to calcium deposits may be involved in phagocytosis of such debris, and may participate in the regulation of ectopic calcification in the ischemic brain.","Overlapping distribution of osteopontin and calcium in the ischemic core of rat brain after transient focal ischemia Abs: Osteopontin (OPN), an adhesive glycoprotein, has recently been proposed to act as an opsonin that facilitates phagocytosis of neuronal debris by macrophages in the ischemic brain. The present study was designed to elucidate the process whereby OPN binds to neuronal cell debris in a rat model of ischemic stroke. Significant co-localization of the OPN protein and calcium deposits in the ischemic core were observed by combining alizarin red staining and OPN immunohistochemistry. In addition, electron microscopy (EM) using the osmium/potassium dichromate method revealed that electron-dense precipitates, typical of calcium deposits, were localized mainly along the periphery of putative degenerating neurites. This topical pattern of calcium precipitates resembled the distribution of OPN as detected by immunogold-silver EM. Combining immunogold-silver EM and electron probe microanalysis further demonstrated that the OPN protein was localized at the periphery of cell debris or degenerating neurites, corresponding with locally higher concentrations of calcium and phosphorus, and that the relative magnitude of OPN accumulation was comparable to that of calcium and phosphorus. These data suggest that calcium precipitation provides a matrix for the binding of the OPN protein within the debris or degenerating neurites induced by ischemic injury. Therefore, OPN binding to calcium deposits may be involved in phagocytosis of such debris, and may participate in the regulation of ectopic calcification in the ischemic brain."
1234074,Zhang et al. 2012,Spectroscopic investigation on the interaction of Cr(VI) with bovine serum albumin,"The interaction of potassium dichromate (Cr(VI)) with bovine serum albumin (BSA) was investigated by fluorescence, synchronous fluorescence, resonance light scattering (RLS), ultraviolet-visible absorption, and circular dichroism (CD) spectroscopies under simulated physiological conditions. The experimental results showed that Cr(VI) could quench the intrinsic fluorescence of BSA following a static quenching process, which indicates the formation of a Cr(VI)-BSA complex. The binding constant (KA) and binding site (n) were measured at different temperatures. The spectroscopic results also revealed that the binding of Cr(VI) to BSA can lead to the loosening of the protein conformation and can change the microenvironment and skeleton of BSA.","Spectroscopic investigation on the interaction of Cr(VI) with bovine serum albumin Abs: The interaction of potassium dichromate (Cr(VI)) with bovine serum albumin (BSA) was investigated by fluorescence, synchronous fluorescence, resonance light scattering (RLS), ultraviolet-visible absorption, and circular dichroism (CD) spectroscopies under simulated physiological conditions. The experimental results showed that Cr(VI) could quench the intrinsic fluorescence of BSA following a static quenching process, which indicates the formation of a Cr(VI)-BSA complex. The binding constant (KA) and binding site (n) were measured at different temperatures. The spectroscopic results also revealed that the binding of Cr(VI) to BSA can lead to the loosening of the protein conformation and can change the microenvironment and skeleton of BSA."
1234072,Molina-Jijón et al. 2012,Deferoxamine pretreatment prevents Cr(VI)-induced nephrotoxicity and oxidant stress: role of Cr(VI) chelation,"Deferoxamine (DFO) is a recognized iron chelator which has been shown to exert nephroprotection in models of toxic nephropathies. In the present work the potential protective effects of DFO against Cr(VI)-induced nephrotoxicity and oxidant stress were evaluated. Rats were injected with a single injection (15mg/kg, s.c.) of potassium dichromate (K(2)Cr(2)O(7)). DFO was given as a single i.p. injection 30min before K(2)Cr(2)O(7) administration at three different doses (100, 200 and 400mg/kg). It was found that DFO pretreatment attenuated, in a dose-dependent way, K(2)Cr(2)O(7)-induced renal dysfunction and structural alterations evaluated by serum creatinine, blood urea nitrogen, creatinine clearance, proteinuria, plasma glutathione peroxidase activity, urinary excretion of N-acetyl-?-d-glucosaminidase and histological analyses. Furthermore, DFO prevented the K(2)Cr(2)O(7)-induced renal oxidant stress and the decrease in the activity of the antioxidant enzymes superoxide dismutase, glutathione reductase, glutathione peroxidase, glutathione-S-transferase and catalase. Finally it was found that DFO, at 400mg/kg, decreases renal Cr(VI) content which prompted us to evaluate the potential Cr(VI) chelating properties of this compound. Indeed was found in an in vitro assay that DFO was an effective Cr(VI) chelator with an IC(50) of 800?g. In additional groups of rats was found that DFO posttreatment was ineffective to attenuate K(2)Cr(2)O(7)-induced nephrotoxicity and renal oxidant stress. Furthermore, DFO was unable to modify urinary excretion of total chromium. The nephroprotective effect of DFO against Cr(VI)-induced nephrotoxicity and oxidant stress may be explained, at least partially, by the ability of DFO to chelate Cr(VI) and to attenuate renal Cr(VI) content. However, it cannot be excluded that the ability of DFO to chelate iron may also be involved in the protection observed in our study.","Deferoxamine pretreatment prevents Cr(VI)-induced nephrotoxicity and oxidant stress: role of Cr(VI) chelation Abs: Deferoxamine (DFO) is a recognized iron chelator which has been shown to exert nephroprotection in models of toxic nephropathies. In the present work the potential protective effects of DFO against Cr(VI)-induced nephrotoxicity and oxidant stress were evaluated. Rats were injected with a single injection (15mg/kg, s.c.) of potassium dichromate (K(2)Cr(2)O(7)). DFO was given as a single i.p. injection 30min before K(2)Cr(2)O(7) administration at three different doses (100, 200 and 400mg/kg). It was found that DFO pretreatment attenuated, in a dose-dependent way, K(2)Cr(2)O(7)-induced renal dysfunction and structural alterations evaluated by serum creatinine, blood urea nitrogen, creatinine clearance, proteinuria, plasma glutathione peroxidase activity, urinary excretion of N-acetyl-?-d-glucosaminidase and histological analyses. Furthermore, DFO prevented the K(2)Cr(2)O(7)-induced renal oxidant stress and the decrease in the activity of the antioxidant enzymes superoxide dismutase, glutathione reductase, glutathione peroxidase, glutathione-S-transferase and catalase. Finally it was found that DFO, at 400mg/kg, decreases renal Cr(VI) content which prompted us to evaluate the potential Cr(VI) chelating properties of this compound. Indeed was found in an in vitro assay that DFO was an effective Cr(VI) chelator with an IC(50) of 800?g. In additional groups of rats was found that DFO posttreatment was ineffective to attenuate K(2)Cr(2)O(7)-induced nephrotoxicity and renal oxidant stress. Furthermore, DFO was unable to modify urinary excretion of total chromium. The nephroprotective effect of DFO against Cr(VI)-induced nephrotoxicity and oxidant stress may be explained, at least partially, by the ability of DFO to chelate Cr(VI) and to attenuate renal Cr(VI) content. However, it cannot be excluded that the ability of DFO to chelate iron may also be involved in the protection observed in our study."
1234071,Pan et al. 2012,Functional proteomics reveals hepatotoxicity and the molecular mechanisms of different forms of chromium delivered by skin administration,"Chromium compounds are known to be associated with cytotoxicity and carcinogenicity when applied via the skin. However, there is no perspective research to elucidate the causations between chromium exposure and hepatotoxicity. In the present study, the impact of hexavalent/trivalent chromium on the liver and the underlying pathogenic processes were revealed in the female nude mice model. The liver damage under different treatments was evaluated by histologic examination. Functional proteome tools combined with a network analysis revealed statistically significant candidate protein networks predicted to be changed in the presence of chromium compounds. RNA interference-mediated silencing and immunohistochemistry were used to confirm whether the candidate protein was capable of resulting in hepatotoxicity elicited by chromium. Potassium chromate as the Cr(VI) compound generated greater oxidative stress, apoptosis and hepatotoxicity compared to chromium nitrate [Cr(III)]-treated samples. The most meaningful changes were observed amongst proteins involved in carbohydrate metabolism, endoplasmic reticulum (ER) stress, calcium homeostasis and apoptosis. Furthermore, abrogation of transitional ER ATPase (VCP) led to significant inhibition in hepatic cell viability under Cr(VI) administration, and the expression profiles of cytokeratin were closely correlated with apoptotic degrees of liver tissue. Collectively, our findings suggest that Cr(VI) might induce the accumulation of misfolded proteins and adverse effects leading to cell apoptosis and liver injury. These signature networks represent an approach to discover novel relationships in complex data, and functional proteomics of liver may provide solid evidence of chromium-caused hepatic damage via the skin.","Functional proteomics reveals hepatotoxicity and the molecular mechanisms of different forms of chromium delivered by skin administration Abs: Chromium compounds are known to be associated with cytotoxicity and carcinogenicity when applied via the skin. However, there is no perspective research to elucidate the causations between chromium exposure and hepatotoxicity. In the present study, the impact of hexavalent/trivalent chromium on the liver and the underlying pathogenic processes were revealed in the female nude mice model. The liver damage under different treatments was evaluated by histologic examination. Functional proteome tools combined with a network analysis revealed statistically significant candidate protein networks predicted to be changed in the presence of chromium compounds. RNA interference-mediated silencing and immunohistochemistry were used to confirm whether the candidate protein was capable of resulting in hepatotoxicity elicited by chromium. Potassium chromate as the Cr(VI) compound generated greater oxidative stress, apoptosis and hepatotoxicity compared to chromium nitrate [Cr(III)]-treated samples. The most meaningful changes were observed amongst proteins involved in carbohydrate metabolism, endoplasmic reticulum (ER) stress, calcium homeostasis and apoptosis. Furthermore, abrogation of transitional ER ATPase (VCP) led to significant inhibition in hepatic cell viability under Cr(VI) administration, and the expression profiles of cytokeratin were closely correlated with apoptotic degrees of liver tissue. Collectively, our findings suggest that Cr(VI) might induce the accumulation of misfolded proteins and adverse effects leading to cell apoptosis and liver injury. These signature networks represent an approach to discover novel relationships in complex data, and functional proteomics of liver may provide solid evidence of chromium-caused hepatic damage via the skin."
1234070,Cristiano et al. 2012,Semi-automated potentiometric titration method for uranium characterization,"The manual version of the potentiometric titration method has been used for certification and characterization of uranium compounds. In order to reduce the analysis time and the influence of the analyst, a semi-automatic version of the method was developed in the Brazilian Nuclear Energy Commission. The method was applied with traceability assured by using a potassium dichromate primary standard. The combined standard uncertainty in determining the total concentration of uranium was around 0.01%, which is suitable for uranium characterization.","Semi-automated potentiometric titration method for uranium characterization Abs: The manual version of the potentiometric titration method has been used for certification and characterization of uranium compounds. In order to reduce the analysis time and the influence of the analyst, a semi-automatic version of the method was developed in the Brazilian Nuclear Energy Commission. The method was applied with traceability assured by using a potassium dichromate primary standard. The combined standard uncertainty in determining the total concentration of uranium was around 0.01%, which is suitable for uranium characterization."
1234067,Arivarasu et al. ,Caffeic Acid Inhibits Chromium(VI)-Induced Oxidative Stress and Changes in Brush Border Membrane Enzymes in Rat Intestine,"We have previously shown that a single oral dose of potassium dichromate results in a decrease in the activities of several brush border membrane enzymes, produces oxidative stress, and alters the activities of several antioxidant enzymes in the small intestine of rats. In the present study, we have investigated the effect of treatment with the dietary antioxidant caffeic acid on potassium dichromate-induced biochemical changes in the rat intestine. Adult male Wistar rats were randomly divided into four groups: control, potassium dichromate alone, caffeic acid alone, and potassium dichromate + caffeic acid. Administration of a single oral dose of potassium dichromate alone (100 mg/kg body mass) led to a decrease in the activities of brush border membrane enzymes, increase in lipid peroxidation, decrease in sulfhydryl groups, and changes in the activities of several antioxidant enzymes. Two oral doses of caffeic acid (each of 250 mg/kg body mass) greatly attenuated the potassium dichromate-induced changes in all these parameters, but the administration of caffeic acid alone had no effect. Thus, caffeic acid is an effective agent in reducing the effects of potassium dichromate on the intestine and could prove to be useful in alleviating the toxicity of chromium(VI) compounds.","Caffeic Acid Inhibits Chromium(VI)-Induced Oxidative Stress and Changes in Brush Border Membrane Enzymes in Rat Intestine Abs: We have previously shown that a single oral dose of potassium dichromate results in a decrease in the activities of several brush border membrane enzymes, produces oxidative stress, and alters the activities of several antioxidant enzymes in the small intestine of rats. In the present study, we have investigated the effect of treatment with the dietary antioxidant caffeic acid on potassium dichromate-induced biochemical changes in the rat intestine. Adult male Wistar rats were randomly divided into four groups: control, potassium dichromate alone, caffeic acid alone, and potassium dichromate + caffeic acid. Administration of a single oral dose of potassium dichromate alone (100 mg/kg body mass) led to a decrease in the activities of brush border membrane enzymes, increase in lipid peroxidation, decrease in sulfhydryl groups, and changes in the activities of several antioxidant enzymes. Two oral doses of caffeic acid (each of 250 mg/kg body mass) greatly attenuated the potassium dichromate-induced changes in all these parameters, but the administration of caffeic acid alone had no effect. Thus, caffeic acid is an effective agent in reducing the effects of potassium dichromate on the intestine and could prove to be useful in alleviating the toxicity of chromium(VI) compounds."
1234065,Amatussalam et al. 2011,In situ Carica papaya stem matrix and Fusarium oxysporum (NCBT-156) mediated bioremediation of chromium,"Removal of heavy metal chromium was carried out using the fungus Fusarium oxysporum NCBT-156 strain isolated from soil of leather tanning effluent in in situ condition using potassium dichromate solution with 10 per cent Czapek-dox liquid medium. Biosorbent matrix was developed using Carica papaya plant dry stem to colonize the fungal strain to facilitate bioabsorption process. Bioabsorption of chromium was by metabolically mediated intracellular accumulation process. Maximum efficiency of chromium removal by biosorption upto 90 per cent was achieved at the end of 5th day of incubation (120 h of contact time) for 100 and 200 ppm concentration, upto 80 per cent for 300 and 400 ppm, and upto 65 per cent for 500 ppm to 1000 ppm concentrations with pH ranging from 5.8, 5.6, 5.5, 5.4 and 5.2, respectively for 100, 200, 300, 400, 500-1000 ppm concentration. SDS-PAGE protein profile showed significant difference in 34 kDa protein band after chromium absorption by the fungus. FTIR spectroscopic analysis revealed that the main functional groups involved in the uptake of chromium by F. oxysporium strain were carbonyl, carboxyl, amino and hydroxyl groups.","In situ Carica papaya stem matrix and Fusarium oxysporum (NCBT-156) mediated bioremediation of chromium Abs: Removal of heavy metal chromium was carried out using the fungus Fusarium oxysporum NCBT-156 strain isolated from soil of leather tanning effluent in in situ condition using potassium dichromate solution with 10 per cent Czapek-dox liquid medium. Biosorbent matrix was developed using Carica papaya plant dry stem to colonize the fungal strain to facilitate bioabsorption process. Bioabsorption of chromium was by metabolically mediated intracellular accumulation process. Maximum efficiency of chromium removal by biosorption upto 90 per cent was achieved at the end of 5th day of incubation (120 h of contact time) for 100 and 200 ppm concentration, upto 80 per cent for 300 and 400 ppm, and upto 65 per cent for 500 ppm to 1000 ppm concentrations with pH ranging from 5.8, 5.6, 5.5, 5.4 and 5.2, respectively for 100, 200, 300, 400, 500-1000 ppm concentration. SDS-PAGE protein profile showed significant difference in 34 kDa protein band after chromium absorption by the fungus. FTIR spectroscopic analysis revealed that the main functional groups involved in the uptake of chromium by F. oxysporium strain were carbonyl, carboxyl, amino and hydroxyl groups."
1234064,Sharmin et al. 2012,Chromium-induced physiological and proteomic alterations in roots of Miscanthus sinensis,"Despite the widespread occurrence of chromium toxicity, its molecular mechanism is poorly documented in plants compared to other heavy metals. To investigate the molecular mechanisms that regulate the response of Miscanthus sinensis roots to elevated level of chromium, seedlings were grown for 4 weeks and exposed to potassium dichromate for 3 days. Physiological, biochemical and proteomic changes in roots were investigated. Lipid peroxidation and H?O? content in roots were significantly increased. Protein profiles analyzed by two-dimensional gel electrophoresis revealed that 36 protein spots were differentially expressed in chromium-treated root samples. Of these, 13 protein spots were up-regulated, 21 protein spots were down-regulated and 2 spots were newly induced. These differentially displayed proteins were identified by MALDI-TOF and MALDI-TOF/TOF mass spectrometry. The identified proteins included known heavy metal-inducible proteins such as carbohydrate and nitrogen metabolism, molecular chaperone proteins and novel proteins such as inositol monophosphatase, nitrate reductase, adenine phosphoribosyl transferase, formate dehydrogenase and a putative dihydrolipoamide dehydrogenase that were not known previously as chromium-responsive. Taken together, these results suggest that Cr toxicity is linked to heavy metal tolerance and senescence pathways, and associated with altered vacuole sequestration, nitrogen metabolism and lipid peroxidation in Miscanthus roots.","Chromium-induced physiological and proteomic alterations in roots of Miscanthus sinensis Abs: Despite the widespread occurrence of chromium toxicity, its molecular mechanism is poorly documented in plants compared to other heavy metals. To investigate the molecular mechanisms that regulate the response of Miscanthus sinensis roots to elevated level of chromium, seedlings were grown for 4 weeks and exposed to potassium dichromate for 3 days. Physiological, biochemical and proteomic changes in roots were investigated. Lipid peroxidation and H?O? content in roots were significantly increased. Protein profiles analyzed by two-dimensional gel electrophoresis revealed that 36 protein spots were differentially expressed in chromium-treated root samples. Of these, 13 protein spots were up-regulated, 21 protein spots were down-regulated and 2 spots were newly induced. These differentially displayed proteins were identified by MALDI-TOF and MALDI-TOF/TOF mass spectrometry. The identified proteins included known heavy metal-inducible proteins such as carbohydrate and nitrogen metabolism, molecular chaperone proteins and novel proteins such as inositol monophosphatase, nitrate reductase, adenine phosphoribosyl transferase, formate dehydrogenase and a putative dihydrolipoamide dehydrogenase that were not known previously as chromium-responsive. Taken together, these results suggest that Cr toxicity is linked to heavy metal tolerance and senescence pathways, and associated with altered vacuole sequestration, nitrogen metabolism and lipid peroxidation in Miscanthus roots."
1234063,Cristiano et al. ,Semi-automatic version of the potentiometric titration method for characterization of uranium compounds,"The potentiometric titration method was used for characterization of uranium compounds to be applied in intercomparison programs. The method is applied with traceability assured using a potassium dichromate primary standard. A semi-automatic version was developed to reduce the analysis time and the operator variation. The standard uncertainty in determining the total concentration of uranium was around 0.01%, which is suitable for uranium characterization and compatible with those obtained by manual techniques.","Semi-automatic version of the potentiometric titration method for characterization of uranium compounds Abs: The potentiometric titration method was used for characterization of uranium compounds to be applied in intercomparison programs. The method is applied with traceability assured using a potassium dichromate primary standard. A semi-automatic version was developed to reduce the analysis time and the operator variation. The standard uncertainty in determining the total concentration of uranium was around 0.01%, which is suitable for uranium characterization and compatible with those obtained by manual techniques."
1234062,Zhao and  Myllylä 2012,Multiparameter measurement of absorbing liquid by time-resolved photoacoustics,"Measuring constituent concentrations of processing liquids provides highly useful data for industrial process control. Techniques that allow online measurement will greatly save resources and energy, making them highly attractive for enterprises. In this paper, we develop a technique based on time-resolved photoacoustics for simultaneously measuring the optical absorption coefficient, acoustic speed, and thermal-acoustic transformation coefficient of an absorbing liquid, using an experimental setup that merely employs a nanosecond pulsed laser with millijoule energy and a single piezoelectric transducer with a wide frequency bandwidth. As investigated samples, we use potassium chromate, glucose, and their mixing solutions. Experimental results show that the value of each parameter measured in a mixed solution is approximately equal to the sum value of the same parameter in the constituent solutions. This means that a simultaneous measurement of these parameters enables us to calculate two or three constituent concentrations in a mixed liquid, if the constituent substances differ clearly from one another in terms of their optical absorption, acoustic speed, or thermal-acoustic transformation properties.","Multiparameter measurement of absorbing liquid by time-resolved photoacoustics Abs: Measuring constituent concentrations of processing liquids provides highly useful data for industrial process control. Techniques that allow online measurement will greatly save resources and energy, making them highly attractive for enterprises. In this paper, we develop a technique based on time-resolved photoacoustics for simultaneously measuring the optical absorption coefficient, acoustic speed, and thermal-acoustic transformation coefficient of an absorbing liquid, using an experimental setup that merely employs a nanosecond pulsed laser with millijoule energy and a single piezoelectric transducer with a wide frequency bandwidth. As investigated samples, we use potassium chromate, glucose, and their mixing solutions. Experimental results show that the value of each parameter measured in a mixed solution is approximately equal to the sum value of the same parameter in the constituent solutions. This means that a simultaneous measurement of these parameters enables us to calculate two or three constituent concentrations in a mixed liquid, if the constituent substances differ clearly from one another in terms of their optical absorption, acoustic speed, or thermal-acoustic transformation properties."
1234061,Doumit and  Pratt 2012,Comparative study of IQ-ultra and Finn Chambers test methodologies in detecting 10 common standard allergens that cause allergic contact dermatitis,"<strong>BACKGROUND: </strong>Patch testing is routinely used in contact dermatitis clinics because it is the gold standard for the evaluation of potential allergic contact dermatitis.<br /><br /><strong>OBJECTIVE: </strong>The study was undertaken to evaluate possible differences in reactivity between the Finn Chamber and IQ-Ultra patch-testing methodologies.<br /><br /><strong>METHODS: </strong>Patients were patch-tested simultaneously with the Finn Chamber and IQ-Ultra patch tests. Ten standard allergens set by the North American Contact Dermatitis Group were used for both techniques.<br /><br /><strong>RESULTS: </strong>Both patch tests had a significant agreement in detecting all of the allergens. An &quot;almost perfect agreement&quot; was noted for ethylenediamine dihydrochloride, quaternium-15, mercapto mix, black rubber mix, balsam of Peru, and nickel sulfate; &quot;substantial agreement&quot; for formaldehyde, bisphenol A epoxy resin, and 4-tert-butylphenol formaldehyde resin; and &quot;moderate agreement&quot; for potassium dichromate.<br /><br /><strong>CONCLUSION: </strong>The Finn Chamber and IQ-Ultra patch tests had a good agreement in the detection of the 10 standard allergens that were tested.","Comparative study of IQ-ultra and Finn Chambers test methodologies in detecting 10 common standard allergens that cause allergic contact dermatitis Abs: <strong>BACKGROUND: </strong>Patch testing is routinely used in contact dermatitis clinics because it is the gold standard for the evaluation of potential allergic contact dermatitis.<br /><br /><strong>OBJECTIVE: </strong>The study was undertaken to evaluate possible differences in reactivity between the Finn Chamber and IQ-Ultra patch-testing methodologies.<br /><br /><strong>METHODS: </strong>Patients were patch-tested simultaneously with the Finn Chamber and IQ-Ultra patch tests. Ten standard allergens set by the North American Contact Dermatitis Group were used for both techniques.<br /><br /><strong>RESULTS: </strong>Both patch tests had a significant agreement in detecting all of the allergens. An &quot;almost perfect agreement&quot; was noted for ethylenediamine dihydrochloride, quaternium-15, mercapto mix, black rubber mix, balsam of Peru, and nickel sulfate; &quot;substantial agreement&quot; for formaldehyde, bisphenol A epoxy resin, and 4-tert-butylphenol formaldehyde resin; and &quot;moderate agreement&quot; for potassium dichromate.<br /><br /><strong>CONCLUSION: </strong>The Finn Chamber and IQ-Ultra patch tests had a good agreement in the detection of the 10 standard allergens that were tested."
1234060,Handa et al. 2012,"Hand eczema: correlation of morphologic patterns, atopy, contact sensitization and disease severity","<strong>BACKGROUND: </strong>Hand eczema is a common distressing condition aggravated by a number of endogenous and exogenous factors. Various morphological forms of hand eczema have been described, but categorization into one of them is not always possible.<br /><br /><strong>AIMS: </strong>To study the morphological patterns of hand eczema, relationship of atopy with hand eczema, and the implications of contact sensitization with respect to severity and diagnosis of hand eczema.<br /><br /><strong>METHODS: </strong>Hundred consecutive patients of hand eczema attending the contact dermatitis clinic of the institute were recruited over a two year period from 2004-05. Objective assessment was done using hand eczema severity index (HECSI) and all the patients were patch tested using Indian standard series.<br /><br /><strong>RESULTS: </strong>Unspecified type of hand eczema with no definite morphologic picture was seen in 62% followed by pompholyx in 14%. Hand eczema severity was not found to be statistically associated with age, sex, and atopic status of the patient. Positive patch test to one or more allergen was present in 65% of patients. The most common allergens were potassium dichromate (25%), fragrance mix (16%), nickel sulphate (14%), and PPD (13%). There was no significant correlation between patch test positivity and hand eczema severity or atopic status of the patient. Among the morphological patterns pompholyx was strongly associated with an atopic status (P=0.004).<br /><br /><strong>CONCLUSIONS: </strong>Hand eczema was seen twice more commonly in men. Atopic and non-atopic patients of hand eczema had no difference in the severity of disease. Contact sensitivity to different allergens did not correlate with increased eczema severity.","Hand eczema: correlation of morphologic patterns, atopy, contact sensitization and disease severity Abs: <strong>BACKGROUND: </strong>Hand eczema is a common distressing condition aggravated by a number of endogenous and exogenous factors. Various morphological forms of hand eczema have been described, but categorization into one of them is not always possible.<br /><br /><strong>AIMS: </strong>To study the morphological patterns of hand eczema, relationship of atopy with hand eczema, and the implications of contact sensitization with respect to severity and diagnosis of hand eczema.<br /><br /><strong>METHODS: </strong>Hundred consecutive patients of hand eczema attending the contact dermatitis clinic of the institute were recruited over a two year period from 2004-05. Objective assessment was done using hand eczema severity index (HECSI) and all the patients were patch tested using Indian standard series.<br /><br /><strong>RESULTS: </strong>Unspecified type of hand eczema with no definite morphologic picture was seen in 62% followed by pompholyx in 14%. Hand eczema severity was not found to be statistically associated with age, sex, and atopic status of the patient. Positive patch test to one or more allergen was present in 65% of patients. The most common allergens were potassium dichromate (25%), fragrance mix (16%), nickel sulphate (14%), and PPD (13%). There was no significant correlation between patch test positivity and hand eczema severity or atopic status of the patient. Among the morphological patterns pompholyx was strongly associated with an atopic status (P=0.004).<br /><br /><strong>CONCLUSIONS: </strong>Hand eczema was seen twice more commonly in men. Atopic and non-atopic patients of hand eczema had no difference in the severity of disease. Contact sensitivity to different allergens did not correlate with increased eczema severity."
1234059,El-Taweel et al. ,Zinc PVA versus potassium dichromate for preservation of microsporidian spores of human origin,"Microsporidia are emerging opportunistic parasites. Preservation of the biological properties of microsporidian spores is often required in research work. The present study compared two preservatives; zinc polyvinyl alcohol (zinc PVA) and potassium dichromate solutions for preservation of microsporidian spores separated from human faecal samples. After 0, 1, 2 and 4 months of storage, morphological features and staining characters of the spores were assessed by light microscopy in modified trichrome-stained smears and their viability percentages were calculated using acridine orange/ethidium bromide mixture. Also, spore infectivity was evaluated by faecal spore shedding and intestinal spore load in mice orally inoculated with the preserved spores. Results revealed that morphological features, staining characters and viability of the spores were maintained in both solutions throughout the study period. Spore infectivity was completely preserved in zinc PVA solution but showed significant reduction in potassium dichromate solution at the fourth month of the preservation duration.","Zinc PVA versus potassium dichromate for preservation of microsporidian spores of human origin Abs: Microsporidia are emerging opportunistic parasites. Preservation of the biological properties of microsporidian spores is often required in research work. The present study compared two preservatives; zinc polyvinyl alcohol (zinc PVA) and potassium dichromate solutions for preservation of microsporidian spores separated from human faecal samples. After 0, 1, 2 and 4 months of storage, morphological features and staining characters of the spores were assessed by light microscopy in modified trichrome-stained smears and their viability percentages were calculated using acridine orange/ethidium bromide mixture. Also, spore infectivity was evaluated by faecal spore shedding and intestinal spore load in mice orally inoculated with the preserved spores. Results revealed that morphological features, staining characters and viability of the spores were maintained in both solutions throughout the study period. Spore infectivity was completely preserved in zinc PVA solution but showed significant reduction in potassium dichromate solution at the fourth month of the preservation duration."
1234058,Chen et al. 2012,Quantitative analysis of powder mixtures by Raman spectrometry: the influence of particle size and its correction,"Particle size distribution and compactness have significant confounding effects on Raman signals of powder mixtures, which cannot be effectively modeled or corrected by traditional multivariate linear calibration methods such as partial least-squares (PLS), and therefore greatly deteriorate the predictive abilities of Raman calibration models for powder mixtures. The ability to obtain directly quantitative information from Raman signals of powder mixtures with varying particle size distribution and compactness is, therefore, of considerable interest. In this study, an advanced quantitative Raman calibration model was developed to explicitly account for the confounding effects of particle size distribution and compactness on Raman signals of powder mixtures. Under the theoretical guidance of the proposed Raman calibration model, an advanced dual calibration strategy was adopted to separate the Raman contributions caused by the changes in mass fractions of the constituents in powder mixtures from those induced by the variations in the physical properties of samples, and hence achieve accurate quantitative determination for powder mixture samples. The proposed Raman calibration model was applied to the quantitative analysis of backscatter Raman measurements of a proof-of-concept model system of powder mixtures consisting of barium nitrate and potassium chromate. The average relative prediction error of prediction obtained by the proposed Raman calibration model was less than one-third of the corresponding value of the best performing PLS model for mass fractions of barium nitrate in powder mixtures with variations in particle size distribution, as well as compactness.","Quantitative analysis of powder mixtures by Raman spectrometry: the influence of particle size and its correction Abs: Particle size distribution and compactness have significant confounding effects on Raman signals of powder mixtures, which cannot be effectively modeled or corrected by traditional multivariate linear calibration methods such as partial least-squares (PLS), and therefore greatly deteriorate the predictive abilities of Raman calibration models for powder mixtures. The ability to obtain directly quantitative information from Raman signals of powder mixtures with varying particle size distribution and compactness is, therefore, of considerable interest. In this study, an advanced quantitative Raman calibration model was developed to explicitly account for the confounding effects of particle size distribution and compactness on Raman signals of powder mixtures. Under the theoretical guidance of the proposed Raman calibration model, an advanced dual calibration strategy was adopted to separate the Raman contributions caused by the changes in mass fractions of the constituents in powder mixtures from those induced by the variations in the physical properties of samples, and hence achieve accurate quantitative determination for powder mixture samples. The proposed Raman calibration model was applied to the quantitative analysis of backscatter Raman measurements of a proof-of-concept model system of powder mixtures consisting of barium nitrate and potassium chromate. The average relative prediction error of prediction obtained by the proposed Raman calibration model was less than one-third of the corresponding value of the best performing PLS model for mass fractions of barium nitrate in powder mixtures with variations in particle size distribution, as well as compactness."
1234057,Moore et al. 2012,Development and application of a database of food ingredient fraud and economically motivated adulteration from 1980 to 2010,"Food ingredient fraud and economically motivated adulteration are emerging risks, but a comprehensive compilation of information about known problematic ingredients and detection methods does not currently exist. The objectives of this research were to collect such information from publicly available articles in scholarly journals and general media, organize into a database, and review and analyze the data to identify trends. The results summarized are a database that will be published in the US Pharmacopeial Convention's Food Chemicals Codex, 8th edition, and includes 1305 records, including 1000 records with analytical methods collected from 677 references. Olive oil, milk, honey, and saffron were the most common targets for adulteration reported in scholarly journals, and potentially harmful issues identified include spices diluted with lead chromate and lead tetraoxide, substitution of Chinese star anise with toxic Japanese star anise, and melamine adulteration of high protein content foods. High-performance liquid chromatography and infrared spectroscopy were the most common analytical detection procedures, and chemometrics data analysis was used in a large number of reports. Future expansion of this database will include additional publically available articles published before 1980 and in other languages, as well as data outside the public domain. The authors recommend in-depth analyses of individual incidents. Practical Application:? This report describes the development and application of a database of food ingredient fraud issues from publicly available references. The database provides baseline information and data useful to governments, agencies, and individual companies assessing the risks of specific products produced in specific regions as well as products distributed and sold in other regions. In addition, the report describes current analytical technologies for detecting food fraud and identifies trends and developments.","Development and application of a database of food ingredient fraud and economically motivated adulteration from 1980 to 2010 Abs: Food ingredient fraud and economically motivated adulteration are emerging risks, but a comprehensive compilation of information about known problematic ingredients and detection methods does not currently exist. The objectives of this research were to collect such information from publicly available articles in scholarly journals and general media, organize into a database, and review and analyze the data to identify trends. The results summarized are a database that will be published in the US Pharmacopeial Convention's Food Chemicals Codex, 8th edition, and includes 1305 records, including 1000 records with analytical methods collected from 677 references. Olive oil, milk, honey, and saffron were the most common targets for adulteration reported in scholarly journals, and potentially harmful issues identified include spices diluted with lead chromate and lead tetraoxide, substitution of Chinese star anise with toxic Japanese star anise, and melamine adulteration of high protein content foods. High-performance liquid chromatography and infrared spectroscopy were the most common analytical detection procedures, and chemometrics data analysis was used in a large number of reports. Future expansion of this database will include additional publically available articles published before 1980 and in other languages, as well as data outside the public domain. The authors recommend in-depth analyses of individual incidents. Practical Application:? This report describes the development and application of a database of food ingredient fraud issues from publicly available references. The database provides baseline information and data useful to governments, agencies, and individual companies assessing the risks of specific products produced in specific regions as well as products distributed and sold in other regions. In addition, the report describes current analytical technologies for detecting food fraud and identifies trends and developments."
1234056,Landeck et al. 2012,Patch test characteristics of patients referred for suspected contact allergy of the feet--retrospective 10-year cross-sectional study of the IVDK data,"<strong>BACKGROUND: </strong>The warm und humid environment, friction and occlusion within shoes make the feet to a favorable body site to acquire allergic contact dermatitis.<br /><br /><strong>OBJECTIVES: </strong>To evaluate and compare patch test results in patients with suspected contact allergy of the feet with the results in those with concomitant involvement of the feet/legs, feet/hands, and all others tested (excluding secondary involvement of the feet in 'others'), with regard to specific patterns of clinical data and patch test results.<br /><br /><strong>METHODS: </strong>For the present cross-sectional study, data were collected by the 59 participating centres of the Information Network of Departments of Dermatology in Germany, Austria, and Switzerland, including 102 209 patients patch-tested between January 2001 and December 2010.<br /><br /><strong>RESULTS: </strong>Allergens that were significantly over-represented in the tested 2671 foot patients included potassium dichromate, colophonium, and p-tert-butylphenol-formaldehyde resin. Among materials brought in by the patients, shoe pieces (27.5%), topical medications/pharmaceutical products (24.4%) and cosmetics (16.8%) played a major role. The final diagnoses of vesicular and hyperkeratotic dermatitis, as well as psoriasis, were significantly more common among foot patients.<br /><br /><strong>CONCLUSIONS: </strong>Chromium compounds and adhesives were the most common causes of allergic contact dermatitis among our foot patients. Psoriasis should be considered, particularly when the hands are concomitantly affected.","Patch test characteristics of patients referred for suspected contact allergy of the feet--retrospective 10-year cross-sectional study of the IVDK data Abs: <strong>BACKGROUND: </strong>The warm und humid environment, friction and occlusion within shoes make the feet to a favorable body site to acquire allergic contact dermatitis.<br /><br /><strong>OBJECTIVES: </strong>To evaluate and compare patch test results in patients with suspected contact allergy of the feet with the results in those with concomitant involvement of the feet/legs, feet/hands, and all others tested (excluding secondary involvement of the feet in 'others'), with regard to specific patterns of clinical data and patch test results.<br /><br /><strong>METHODS: </strong>For the present cross-sectional study, data were collected by the 59 participating centres of the Information Network of Departments of Dermatology in Germany, Austria, and Switzerland, including 102 209 patients patch-tested between January 2001 and December 2010.<br /><br /><strong>RESULTS: </strong>Allergens that were significantly over-represented in the tested 2671 foot patients included potassium dichromate, colophonium, and p-tert-butylphenol-formaldehyde resin. Among materials brought in by the patients, shoe pieces (27.5%), topical medications/pharmaceutical products (24.4%) and cosmetics (16.8%) played a major role. The final diagnoses of vesicular and hyperkeratotic dermatitis, as well as psoriasis, were significantly more common among foot patients.<br /><br /><strong>CONCLUSIONS: </strong>Chromium compounds and adhesives were the most common causes of allergic contact dermatitis among our foot patients. Psoriasis should be considered, particularly when the hands are concomitantly affected."
1234055,Niranjanmurthi et al. 2012,Fabrication of conducting poly(3-thiophene boronic acid)-grafted multi-walled carbon nanotubes by oxidative polymerization,"Composite materials of multi-walled carbon nanotubes (MWNTs) and a conducting polymer, poly(3-thiophene boronic acid) (PTBA) were prepared by in-situ oxidative polymerization of TBA in the presence of MWNTs and potassium dichromate. The MWNTs which were previously surface functionalized with acid chloride groups were reacted with TBA using a simple &quot;chemical grafting&quot; technique. It was observed that the nanotubes were dispersed uniformly in the pi-conjugated polymer matrix and entrapped by the polymer. The conductivity of the composites was higher than that of the pure polymer from a conventional four-probe technique, which indicates that the fabrication of MWNTs into the polymer matrix significantly improves the conductivity of the polymer due to the intrinsic properties of MWNTs.","Fabrication of conducting poly(3-thiophene boronic acid)-grafted multi-walled carbon nanotubes by oxidative polymerization Abs: Composite materials of multi-walled carbon nanotubes (MWNTs) and a conducting polymer, poly(3-thiophene boronic acid) (PTBA) were prepared by in-situ oxidative polymerization of TBA in the presence of MWNTs and potassium dichromate. The MWNTs which were previously surface functionalized with acid chloride groups were reacted with TBA using a simple &quot;chemical grafting&quot; technique. It was observed that the nanotubes were dispersed uniformly in the pi-conjugated polymer matrix and entrapped by the polymer. The conductivity of the composites was higher than that of the pure polymer from a conventional four-probe technique, which indicates that the fabrication of MWNTs into the polymer matrix significantly improves the conductivity of the polymer due to the intrinsic properties of MWNTs."
1234054,Sultan and  Hasnain 2012,Chromium (VI) Reduction by Cell Free Extract of Ochrobactrum anthropi Isolated from Tannery Effluent,"Chromium-resistant bacteria isolated from industrial wastes can be used to detoxify toxic chromium from contaminated sources. From effluent of Shafiq Tannery, Kasur, Pakistan, bacterial strain STCr-1 that could endure 40 mg mL(-1) of potassium chromate in nutrient agar medium was isolated. STCr-1, identified as Ochrobactrum anthropi by 16S rRNA gene sequence homology, demonstrated substantial Cr(VI) reduction at pH 7 and temperature 37°C. It completely reduced 250 ?g mL(-1) of Cr(VI) and showed 71.2 % Cr(VI) reduction at Cr(VI) concentrations of 550 ?g mL(-1). Rate of Cr(VI) reduction increased with increase in cell and Cr(VI) concentration. The presence of Cu(2+), Co(2+) and Mn(2+) significantly stimulated Cr(VI) reduction. Assay with cell free extracts clearly indicated that Cr(VI) reduction was solely associated with the soluble fraction of the cell.","Chromium (VI) Reduction by Cell Free Extract of Ochrobactrum anthropi Isolated from Tannery Effluent Abs: Chromium-resistant bacteria isolated from industrial wastes can be used to detoxify toxic chromium from contaminated sources. From effluent of Shafiq Tannery, Kasur, Pakistan, bacterial strain STCr-1 that could endure 40 mg mL(-1) of potassium chromate in nutrient agar medium was isolated. STCr-1, identified as Ochrobactrum anthropi by 16S rRNA gene sequence homology, demonstrated substantial Cr(VI) reduction at pH 7 and temperature 37°C. It completely reduced 250 ?g mL(-1) of Cr(VI) and showed 71.2 % Cr(VI) reduction at Cr(VI) concentrations of 550 ?g mL(-1). Rate of Cr(VI) reduction increased with increase in cell and Cr(VI) concentration. The presence of Cu(2+), Co(2+) and Mn(2+) significantly stimulated Cr(VI) reduction. Assay with cell free extracts clearly indicated that Cr(VI) reduction was solely associated with the soluble fraction of the cell."
1234053,Febriana et al. ,Occupational allergic contact dermatitis and patch test results of leather workers at two Indonesian tanneries,"Background. Tannery workers are at considerable risk of developing occupational contact dermatitis. Occupational skin diseases in tannery workers in newly industrialized countries have been reported, but neither the prevalence of occupational allergic contact dermatitis nor the skin-sensitizing agents were specifically examined in those studies. Objectives. To assess the prevalence of occupational allergic contact dermatitis in Indonesian tanneries, identify the causative allergens, and propose a tannery work series of patch test allergens. Patients/methods A cross-sectional study in all workers at two Indonesian tanneries was performed to assess the prevalence of occupational contact dermatitis via a questionnaire-based interview and skin examination. Workers with occupational contact dermatitis were patch tested to identify the causative allergens. Results. Occupational contact dermatitis was suspected in 77 (16%) of the 472 workers. Thirteen (3%) of these 472 workers were confirmed to have occupational allergic contact dermatitis. Potassium dichromate (9.2%), N,N-diphenylguanidine (5.3%), benzidine (3.9%) and sodium metabisulfite (2.6%) were found to be the occupationally relevant sensitizers. Conclusions. The sensitization pattern showed some differences from the data in studies reported from other newly industrial countries. We compiled a 'tannery work series' of allergens for patch testing. A number of these allergens may also be considered for patch testing in patients with (leather) shoe dermatitis.","Occupational allergic contact dermatitis and patch test results of leather workers at two Indonesian tanneries Abs: Background. Tannery workers are at considerable risk of developing occupational contact dermatitis. Occupational skin diseases in tannery workers in newly industrialized countries have been reported, but neither the prevalence of occupational allergic contact dermatitis nor the skin-sensitizing agents were specifically examined in those studies. Objectives. To assess the prevalence of occupational allergic contact dermatitis in Indonesian tanneries, identify the causative allergens, and propose a tannery work series of patch test allergens. Patients/methods A cross-sectional study in all workers at two Indonesian tanneries was performed to assess the prevalence of occupational contact dermatitis via a questionnaire-based interview and skin examination. Workers with occupational contact dermatitis were patch tested to identify the causative allergens. Results. Occupational contact dermatitis was suspected in 77 (16%) of the 472 workers. Thirteen (3%) of these 472 workers were confirmed to have occupational allergic contact dermatitis. Potassium dichromate (9.2%), N,N-diphenylguanidine (5.3%), benzidine (3.9%) and sodium metabisulfite (2.6%) were found to be the occupationally relevant sensitizers. Conclusions. The sensitization pattern showed some differences from the data in studies reported from other newly industrial countries. We compiled a 'tannery work series' of allergens for patch testing. A number of these allergens may also be considered for patch testing in patients with (leather) shoe dermatitis."
1234052,Singh et al. 2012,Animal models of acute renal failure,"The animal models are pivotal for understanding the characteristics of acute renal failure (ARF) and development of effective therapy for its optimal management. Since the etiology for induction of renal failure is multifold, therefore, a large number of animal models have been developed to mimic the clinical conditions of renal failure. Glycerol-induced renal failure closely mimics the rhabdomyolysis; ischemia-reperfusion-induced ARF simulate the hemodynamic changes-induced changes in renal functioning; drug-induced such as gentamicin, cisplatin, NSAID, ifosfamide-induced ARF mimics the renal failure due to clinical administration of respective drugs; uranium, potassium dichromate-induced ARF mimics the occupational hazard; S-(1,2-dichlorovinyl)-L-cysteine-induced ARF simulate contaminated water-induced renal dysfunction; sepsis-induced ARF mimics the infection-induced renal failure and radiocontrast-induced ARF mimics renal failure in patients during use of radiocontrast media at the time of cardiac catheterization. Since each animal model has been created with specific methodology, therefore, it is essential to describe the model in detail and consequently interpret the results in the context of a specific model.","Animal models of acute renal failure Abs: The animal models are pivotal for understanding the characteristics of acute renal failure (ARF) and development of effective therapy for its optimal management. Since the etiology for induction of renal failure is multifold, therefore, a large number of animal models have been developed to mimic the clinical conditions of renal failure. Glycerol-induced renal failure closely mimics the rhabdomyolysis; ischemia-reperfusion-induced ARF simulate the hemodynamic changes-induced changes in renal functioning; drug-induced such as gentamicin, cisplatin, NSAID, ifosfamide-induced ARF mimics the renal failure due to clinical administration of respective drugs; uranium, potassium dichromate-induced ARF mimics the occupational hazard; S-(1,2-dichlorovinyl)-L-cysteine-induced ARF simulate contaminated water-induced renal dysfunction; sepsis-induced ARF mimics the infection-induced renal failure and radiocontrast-induced ARF mimics renal failure in patients during use of radiocontrast media at the time of cardiac catheterization. Since each animal model has been created with specific methodology, therefore, it is essential to describe the model in detail and consequently interpret the results in the context of a specific model."
1234051,Gu et al. ,High resolution micro arthrography of hard and soft tissues in a murine model,"OBJECTIVE: Recent developments on high resolution micro computed tomography (?CT) allow imaging of soft tissues in small animal joints. Nevertheless, ?CT images cannot distinguish soft tissues from synovial fluid due to their similar mass density, limiting the 3D assessment of soft tissues volume and thickness. This study aimed to evaluate a lead chromate contrast agent for ?C? arthrography of rat knee joints ex vivo. DESIGN: Intact tibiofemoral rat joints were injected with the contrast agent at different concentrations and imaged using a ?CT at 2.7 ?m isotropic voxel size. Cartilage thickness was measured using an automated procedure, validated against histological measurements, and analyzed as a function of ?CT image resolution. Changes in hard and soft tissues were also analyzed in tibiofemoral joints 4 weeks after surgical destabilization of the medial meniscus (DMM). RESULTS: The contrast agent diffused well throughout the whole knee cavity without penetrating the tissues, therefore providing high contrast at the boundaries between soft tissues and synovial fluid space. Thickness analysis of cartilage demonstrated a high similarity between histology and ?-arthrography approaches (R(2) = 0.90). Four weeks after surgical DMM, the development of osteophytes (Oph) and cartilage ulcerations was recognizable with ?CT, as well as a slight increase in trabecular bone porosity, and decrease in trabecular thickness. CONCLUSIONS: A lead chromate-based contrast agent allowed discriminating the synovial fluid from soft tissues of intact knee joints, and thus made possible both qualitative and quantitative assessment of hard and soft tissues in both intact and DMM tibiofemoral joints using high resolution ?CT.","High resolution micro arthrography of hard and soft tissues in a murine model Abs: OBJECTIVE: Recent developments on high resolution micro computed tomography (?CT) allow imaging of soft tissues in small animal joints. Nevertheless, ?CT images cannot distinguish soft tissues from synovial fluid due to their similar mass density, limiting the 3D assessment of soft tissues volume and thickness. This study aimed to evaluate a lead chromate contrast agent for ?C? arthrography of rat knee joints ex vivo. DESIGN: Intact tibiofemoral rat joints were injected with the contrast agent at different concentrations and imaged using a ?CT at 2.7 ?m isotropic voxel size. Cartilage thickness was measured using an automated procedure, validated against histological measurements, and analyzed as a function of ?CT image resolution. Changes in hard and soft tissues were also analyzed in tibiofemoral joints 4 weeks after surgical destabilization of the medial meniscus (DMM). RESULTS: The contrast agent diffused well throughout the whole knee cavity without penetrating the tissues, therefore providing high contrast at the boundaries between soft tissues and synovial fluid space. Thickness analysis of cartilage demonstrated a high similarity between histology and ?-arthrography approaches (R(2) = 0.90). Four weeks after surgical DMM, the development of osteophytes (Oph) and cartilage ulcerations was recognizable with ?CT, as well as a slight increase in trabecular bone porosity, and decrease in trabecular thickness. CONCLUSIONS: A lead chromate-based contrast agent allowed discriminating the synovial fluid from soft tissues of intact knee joints, and thus made possible both qualitative and quantitative assessment of hard and soft tissues in both intact and DMM tibiofemoral joints using high resolution ?CT."
1234050,Dou et al. 2011,Prevalence of contact allergy at a dermatology clinic in china from 1990-2009,"<strong>BACKGROUND: </strong>: The prevalence of contact allergy varies in different regions and populations.<br /><br /><strong>OBJECTIVE: </strong>: To describe the frequency of sensitization in patients with dermatitis or eczema referred to Peking University First Hospital and analyze the trends in the prevalence of common allergens from January 1, 1990, to December 31, 2009.<br /><br /><strong>METHODS: </strong>: A total of 1,858 patients were patch tested with the Chinese baseline series of contact allergens. Data were collected from retrospective charts and analyzed.<br /><br /><strong>RESULTS: </strong>: Positive reactions to one or more allergens were shown in 1,374 patients (74.0%). The most common sensitizers were nickel sulfate (25.7%), fragrance mix I (25.6%), thiuram mix (25.5%), ammoniated mercury (20.5%), and p-phenylenediamine (19.1%). A statistically significant increase of sensitization over the 20-year period was seen for nickel sulfate, fragrance mix, ammoniated mercury, colophony, ethylenediamine, and potassium dichromate. Mercapto mix showed a trend of a statistically significant decrease in sensitizations from 1990 to 2009.<br /><br /><strong>CONCLUSIONS: </strong>: The patterns of contact allergy in patients from Peking University Hospital are different from those of patients in other regions of China, in European countries, and in the United States. Nickel and fragrance mix were the most common allergens, and the sensitization rates of these two allergens had been increasing remarkably during the 20 years from 1990 to 2009.","Prevalence of contact allergy at a dermatology clinic in china from 1990-2009 Abs: <strong>BACKGROUND: </strong>: The prevalence of contact allergy varies in different regions and populations.<br /><br /><strong>OBJECTIVE: </strong>: To describe the frequency of sensitization in patients with dermatitis or eczema referred to Peking University First Hospital and analyze the trends in the prevalence of common allergens from January 1, 1990, to December 31, 2009.<br /><br /><strong>METHODS: </strong>: A total of 1,858 patients were patch tested with the Chinese baseline series of contact allergens. Data were collected from retrospective charts and analyzed.<br /><br /><strong>RESULTS: </strong>: Positive reactions to one or more allergens were shown in 1,374 patients (74.0%). The most common sensitizers were nickel sulfate (25.7%), fragrance mix I (25.6%), thiuram mix (25.5%), ammoniated mercury (20.5%), and p-phenylenediamine (19.1%). A statistically significant increase of sensitization over the 20-year period was seen for nickel sulfate, fragrance mix, ammoniated mercury, colophony, ethylenediamine, and potassium dichromate. Mercapto mix showed a trend of a statistically significant decrease in sensitizations from 1990 to 2009.<br /><br /><strong>CONCLUSIONS: </strong>: The patterns of contact allergy in patients from Peking University Hospital are different from those of patients in other regions of China, in European countries, and in the United States. Nickel and fragrance mix were the most common allergens, and the sensitization rates of these two allergens had been increasing remarkably during the 20 years from 1990 to 2009."
1234049,Hession and  Scheinman 2012,The role of contact allergens in chronic idiopathic urticaria,"<strong>OBJECTIVE: </strong>The objective of this study was to determine whether contact allergens play a role in chronic idiopathic urticaria (CIU).<br /><br /><strong>METHODS: </strong>We conducted a longitudinal prospective study of 23 patients with CIU. Patients were patch tested to a modified North American Contact Dermatitis Group standard, fragrance, and cosmetic series; other series were tested as warranted by relevant history and physical examination. Readings were performed at 48 and 72 hours. Patients were counseled to avoid proven contact allergens and were followed up 2 to 9 months after testing.<br /><br /><strong>RESULTS: </strong>Twenty-one of 23 patients were female. The mean age was 46 years. The mean duration of urticaria was 32 months. Of the 23 patients, 8 (35%) experienced improvement of their symptoms with allergen avoidance. Four (17%) experienced a complete remission, and 4 (17%) experienced partial improvement. Two of the complete responders challenged themselves to proven contact allergens and developed urticaria, which resolved upon allergen avoidance. The most common allergens were potassium dichromate (n = 9), nickel sulfate (n = 7), Myroxylon pereirae (n = 6), cobalt chloride, neomycin, p-phenylenediamine (n = 5); fragrance mix I, fragrance mix II (n = 4); cinnamic aldehyde (n = 3); and formaldehyde (n = 2).<br /><br /><strong>CONCLUSIONS: </strong>Patch testing may be helpful in the evaluation of CIU patients for whom previous workup has failed to reveal an etiology.","The role of contact allergens in chronic idiopathic urticaria Abs: <strong>OBJECTIVE: </strong>The objective of this study was to determine whether contact allergens play a role in chronic idiopathic urticaria (CIU).<br /><br /><strong>METHODS: </strong>We conducted a longitudinal prospective study of 23 patients with CIU. Patients were patch tested to a modified North American Contact Dermatitis Group standard, fragrance, and cosmetic series; other series were tested as warranted by relevant history and physical examination. Readings were performed at 48 and 72 hours. Patients were counseled to avoid proven contact allergens and were followed up 2 to 9 months after testing.<br /><br /><strong>RESULTS: </strong>Twenty-one of 23 patients were female. The mean age was 46 years. The mean duration of urticaria was 32 months. Of the 23 patients, 8 (35%) experienced improvement of their symptoms with allergen avoidance. Four (17%) experienced a complete remission, and 4 (17%) experienced partial improvement. Two of the complete responders challenged themselves to proven contact allergens and developed urticaria, which resolved upon allergen avoidance. The most common allergens were potassium dichromate (n = 9), nickel sulfate (n = 7), Myroxylon pereirae (n = 6), cobalt chloride, neomycin, p-phenylenediamine (n = 5); fragrance mix I, fragrance mix II (n = 4); cinnamic aldehyde (n = 3); and formaldehyde (n = 2).<br /><br /><strong>CONCLUSIONS: </strong>Patch testing may be helpful in the evaluation of CIU patients for whom previous workup has failed to reveal an etiology."
1234048,Samitz et al. 1962,Inactivation of hexavalent chromium. Studies of an antichrome agent,,Inactivation of hexavalent chromium. Studies of an antichrome agent Abs: 
1234042,Schroeder and  Nason 1976,"Interactions of trace metals in mouse and rat tissues; zinc, chromium, copper, and manganese with 13 other elements","Tissues of rats and mice fed a nonessential metal in drinking water for life were analyzed for the essential metals chromium, copper, manganese and zinc. The study involved 505 rats and 843 mice. Livers, lungs, hearts, kidneys and spleens were pooled in groups according to age at death, averaging 5 for rats and 8 for mice, in order to provide adequate sample weight. Copper was significantly higher in livers of rats fed tin, germanium, niobium and zirconium than in controls. Similarly, niobium was associated with deposition of manganese in heart and zinc deposition in liver. Chromium levels were depressed in heart, kidney and spleen by germanium. In mice the greatest effects occurred when indium and rhodium were fed, all four essential trace metals exhibiting raised levels principally in kidney but also in heart and spleen. Chromium levels were raised in all organs but heart when hexavalent chromium was fed. From these data it is apparent that the ingestion of a nonessential metal can enhance the retention of an essential trace metal, perhaps thus avoiding toxicity from the nonessential one.","Interactions of trace metals in mouse and rat tissues; zinc, chromium, copper, and manganese with 13 other elements Abs: Tissues of rats and mice fed a nonessential metal in drinking water for life were analyzed for the essential metals chromium, copper, manganese and zinc. The study involved 505 rats and 843 mice. Livers, lungs, hearts, kidneys and spleens were pooled in groups according to age at death, averaging 5 for rats and 8 for mice, in order to provide adequate sample weight. Copper was significantly higher in livers of rats fed tin, germanium, niobium and zirconium than in controls. Similarly, niobium was associated with deposition of manganese in heart and zinc deposition in liver. Chromium levels were depressed in heart, kidney and spleen by germanium. In mice the greatest effects occurred when indium and rhodium were fed, all four essential trace metals exhibiting raised levels principally in kidney but also in heart and spleen. Chromium levels were raised in all organs but heart when hexavalent chromium was fed. From these data it is apparent that the ingestion of a nonessential metal can enhance the retention of an essential trace metal, perhaps thus avoiding toxicity from the nonessential one."
1234041,Eisler and  Hennekey 1977,"Acute toxicities of Cd2+, Cr+6 Hg2+, Ni2+ and Zn2+ to estuarine macrofauna","Static acute toxicity bioassays were conducted at 20 degrees C and 20 o/33 salinity with CdCl2-2 1/2 H20, K2CrO4, HgCl2, NiCl2-6H2O, and ZnCl2 using adults of starfish, Asterias forbesi; sandworm, Nereis virens; hermit crab, Pagurus longicarpus; softshell clam, Mya arenaria; mudsnail, Nassarius obsoletus; and mummichog, Fundulus heteroclitus, a fish. Concentrations (mg/L metal) fatal to 50% of the organisms in 168 hr ranged from 0.004 (clam) to 0.8 (mummichog) for mercury; 0.7 (clam, worm, crab and starfish) to 40.0 (mummichog) for cadimium; 0.2 (crab) to 52.0 (mummichog) for zinc; 0.7 (sandworm) to 44.0 (mummichog) for hexavalent chromium; and 13.0 (starfish) to 150.0 (mummichog) for nickel. Biocidal action was restricted to a relatively narrow range for all species-metals combinations tested: i.e., mean LC-75/LC-25 rations for individual metals at 168 hr ranged between 2.82 (Zn) and 6.02 (Cd); for individual species this ratio extended from 2.76 (fish) to 4.46 (clam). It appears that acute toxicity evaluation of potentially hazardous metals in saline environments requires utilization of at least several representative species from divergent taxonomic and ecological niches.","Acute toxicities of Cd2+, Cr+6 Hg2+, Ni2+ and Zn2+ to estuarine macrofauna Abs: Static acute toxicity bioassays were conducted at 20 degrees C and 20 o/33 salinity with CdCl2-2 1/2 H20, K2CrO4, HgCl2, NiCl2-6H2O, and ZnCl2 using adults of starfish, Asterias forbesi; sandworm, Nereis virens; hermit crab, Pagurus longicarpus; softshell clam, Mya arenaria; mudsnail, Nassarius obsoletus; and mummichog, Fundulus heteroclitus, a fish. Concentrations (mg/L metal) fatal to 50% of the organisms in 168 hr ranged from 0.004 (clam) to 0.8 (mummichog) for mercury; 0.7 (clam, worm, crab and starfish) to 40.0 (mummichog) for cadimium; 0.2 (crab) to 52.0 (mummichog) for zinc; 0.7 (sandworm) to 44.0 (mummichog) for hexavalent chromium; and 13.0 (starfish) to 150.0 (mummichog) for nickel. Biocidal action was restricted to a relatively narrow range for all species-metals combinations tested: i.e., mean LC-75/LC-25 rations for individual metals at 168 hr ranged between 2.82 (Zn) and 6.02 (Cd); for individual species this ratio extended from 2.76 (fish) to 4.46 (clam). It appears that acute toxicity evaluation of potentially hazardous metals in saline environments requires utilization of at least several representative species from divergent taxonomic and ecological niches."
1234037,Hedenstedt et al. 1977,Mutagenicity of fume particles from stainless steel welding,"Welding fume particles collected from different welding procedures were tested for mutagenicity in Escherichia coli, with the inhibition zone in pol A- as compared to pol A+, and in Salmonella typhimurium, TA 100 strain. While no mutagenicity was found with mild steel welding, a mutagenic effect was established with samples from stainless steel welding. This mutagenicity was particularly associated with manual metal arc (MMA) welding, and less so with metal inert-gas welding. A decrease in or an elimination of the effect occurred with a liver microsomal metabolizing system (S-9 mix). The MMA samples produced the strongest mutagenic effect. More-detailed investigations on these samples showed that the mutagenic agent(s) is water soluble. An increased mutagenicity, which also revealed the induction of frame shift mutations, was found with TA 98. The same welding fume sample was used for a mutagenicity test (resistance to 6-thioguanine) with V 79 hamster cells. Because of the high toxicity of these welding fume particles on the cells, only very low concentrations could be tested, but the increase of mutations, when compared to the negative control, was significant. It is suggested that hexavalent chromium may be involved in the mutagenic effect of the welding fumes.","Mutagenicity of fume particles from stainless steel welding Abs: Welding fume particles collected from different welding procedures were tested for mutagenicity in Escherichia coli, with the inhibition zone in pol A- as compared to pol A+, and in Salmonella typhimurium, TA 100 strain. While no mutagenicity was found with mild steel welding, a mutagenic effect was established with samples from stainless steel welding. This mutagenicity was particularly associated with manual metal arc (MMA) welding, and less so with metal inert-gas welding. A decrease in or an elimination of the effect occurred with a liver microsomal metabolizing system (S-9 mix). The MMA samples produced the strongest mutagenic effect. More-detailed investigations on these samples showed that the mutagenic agent(s) is water soluble. An increased mutagenicity, which also revealed the induction of frame shift mutations, was found with TA 98. The same welding fume sample was used for a mutagenicity test (resistance to 6-thioguanine) with V 79 hamster cells. Because of the high toxicity of these welding fume particles on the cells, only very low concentrations could be tested, but the increase of mutations, when compared to the negative control, was significant. It is suggested that hexavalent chromium may be involved in the mutagenic effect of the welding fumes."
1234031,Fales 1978,The influence of temperature and salinity on the toxicity of hexavalent chromium to the grass shrimp Palaemonetes pugio (Holthuis),,The influence of temperature and salinity on the toxicity of hexavalent chromium to the grass shrimp Palaemonetes pugio (Holthuis) Abs: 
1234025,Majone and  Levis 1979,Chromosomal aberrations and sister-chromatid exchanges in Chinese hamster cells treated in vitro with hexavalent chromium compounds,"Chinese hamster cells (CHO line) were treated in vitro for 30--39 h with hexavalent chromium compounds (K2Cr2O7 and Na2CrO7), at concentrations ranging from 0.1 to 1.0 microgram of Cr6+ per ml, in medium containing BUdr. Chromosomal aberrations and sister-chromatid exchanges were scored on BUdr-labelled 2nd division metaphases, collected at the end of treatment and stained with Giemsa. Treatment with mitomycin C 0.009--0.030 microgram/ml) was carried out as a control for the responsiveness of the cell system to chromosomal damage. Both chromium compounds induced marked mitotic delays. Chromosomal aberrations were increased about 10-fold by exposure to Cr6+ (1.0 microgram/ml). The principal aberrations observed were single chromatid gaps, breaks and interchanges, whose frequencies increased proportionally to the concentration of chromium. Dicentric chromosomes, isochromatid breaks, chromosome and chromatid rings were also induced. The frequenyc of sister-chromatid exchanges was hardly doubled 30 h after exposure to Cr6+ at 0.3 microgram/ml, whereas it was trebled 39 h after treatment, in the cells whose division cycle had been slowed down by chromium.","Chromosomal aberrations and sister-chromatid exchanges in Chinese hamster cells treated in vitro with hexavalent chromium compounds Abs: Chinese hamster cells (CHO line) were treated in vitro for 30--39 h with hexavalent chromium compounds (K2Cr2O7 and Na2CrO7), at concentrations ranging from 0.1 to 1.0 microgram of Cr6+ per ml, in medium containing BUdr. Chromosomal aberrations and sister-chromatid exchanges were scored on BUdr-labelled 2nd division metaphases, collected at the end of treatment and stained with Giemsa. Treatment with mitomycin C 0.009--0.030 microgram/ml) was carried out as a control for the responsiveness of the cell system to chromosomal damage. Both chromium compounds induced marked mitotic delays. Chromosomal aberrations were increased about 10-fold by exposure to Cr6+ (1.0 microgram/ml). The principal aberrations observed were single chromatid gaps, breaks and interchanges, whose frequencies increased proportionally to the concentration of chromium. Dicentric chromosomes, isochromatid breaks, chromosome and chromatid rings were also induced. The frequenyc of sister-chromatid exchanges was hardly doubled 30 h after exposure to Cr6+ at 0.3 microgram/ml, whereas it was trebled 39 h after treatment, in the cells whose division cycle had been slowed down by chromium."
1234024,Thomsen and  Stern 1979,A simple analytical technique for the determination of hexavalent chromium in welding fumes and other complex matrices,"A systematic study of analytical methods for the determination of hexavalent chromium showed that currently existing techniques are unsatisfactory when used with welding fumes, the s-diphenylcarbazide method proposed by the U.S. National Institute for Occupational Safety and Health permitting less than 1% recovery of hexavalent chromium from synthetic welding fumes of known composition. A new (carbonate leaching) technique is proposed which permits better than 80% recovery of both soluble and insoluble chromium (VI). This technique is then used as part of a general method for the determination of total chemical composition as distributed among sample fractions of different solubility. The method is specifically designed for use in the analysis of small samples and is especially suitable for the routine evaluation of health risks as found in the work environment.","A simple analytical technique for the determination of hexavalent chromium in welding fumes and other complex matrices Abs: A systematic study of analytical methods for the determination of hexavalent chromium showed that currently existing techniques are unsatisfactory when used with welding fumes, the s-diphenylcarbazide method proposed by the U.S. National Institute for Occupational Safety and Health permitting less than 1% recovery of hexavalent chromium from synthetic welding fumes of known composition. A new (carbonate leaching) technique is proposed which permits better than 80% recovery of both soluble and insoluble chromium (VI). This technique is then used as part of a general method for the determination of total chemical composition as distributed among sample fractions of different solubility. The method is specifically designed for use in the analysis of small samples and is especially suitable for the routine evaluation of health risks as found in the work environment."
1234023,Milner 1980,Ascorbic acid in the prevention of chromium dermatitis,"A worker with strong chromium sensitivity was obliged to handle freshly printed paper with inks containing chromium. Because of his importance to the firm, he continued in the position despite a severe hand dermatitis. Gloves and barrier creams were unacceptable, as were oral antihistamines and corticosteroids. A solution of 10% ascorbic acid was applied to his hands at the worksite in order to reduce the active hexavalent chromium to the inactive trivalent form. This inexpensive, easy-to-use method resulted in a speedy recovery and long-term employment of a valued employee.","Ascorbic acid in the prevention of chromium dermatitis Abs: A worker with strong chromium sensitivity was obliged to handle freshly printed paper with inks containing chromium. Because of his importance to the firm, he continued in the position despite a severe hand dermatitis. Gloves and barrier creams were unacceptable, as were oral antihistamines and corticosteroids. A solution of 10% ascorbic acid was applied to his hands at the worksite in order to reduce the active hexavalent chromium to the inactive trivalent form. This inexpensive, easy-to-use method resulted in a speedy recovery and long-term employment of a valued employee."
1234022,Shmitova 1980,[Content of hexavalent chromium in the biological substrates of pregnant women and puerperae engaged in the manufacture of chromium compounds],,[Content of hexavalent chromium in the biological substrates of pregnant women and puerperae engaged in the manufacture of chromium compounds] Abs: 
1234020,Knudsen 1980,The mammalian spot test and its use for the testing of potential carcinogenicity of welding fume particles and hexavalent chromium,"Welding fume particles, potassium chromate and cyclophosphamide are tested in the mammalian spot test. Female mice C57BL/6J/BOM9 weeks old have been mated to T-stock male mice and treated with welding fume particles 100 mg/kg, potassium chromate 20 or 10 mg/kg, or cyclophosphamide 10 or 2.5 mg/kg intraperitoneally at day 8, 9 and 10 of pregnancy. The fur of the offspring was checked week 2 through week 5 after birth for coloured spots. The characterisation of the different types of spots are discussed. Welding fume particles 100 mg/kg and potassium chromate 10 mg/kg induce approximately to the same extent as cyclophosphamde 2.5 mg/kg, grayish or brownish spots in tvo screening test for mutagenic and carcinogenic potential of chemicals. The positive results for potassium chromate and cyclophosphamide are in agreement with previous in vitro experiments and confirm the sensitivity of the test. The effect of welding fume particles in this in vivo system suggests a potential risk for humans directly exposed to welding fumes.","The mammalian spot test and its use for the testing of potential carcinogenicity of welding fume particles and hexavalent chromium Abs: Welding fume particles, potassium chromate and cyclophosphamide are tested in the mammalian spot test. Female mice C57BL/6J/BOM9 weeks old have been mated to T-stock male mice and treated with welding fume particles 100 mg/kg, potassium chromate 20 or 10 mg/kg, or cyclophosphamide 10 or 2.5 mg/kg intraperitoneally at day 8, 9 and 10 of pregnancy. The fur of the offspring was checked week 2 through week 5 after birth for coloured spots. The characterisation of the different types of spots are discussed. Welding fume particles 100 mg/kg and potassium chromate 10 mg/kg induce approximately to the same extent as cyclophosphamde 2.5 mg/kg, grayish or brownish spots in tvo screening test for mutagenic and carcinogenic potential of chemicals. The positive results for potassium chromate and cyclophosphamide are in agreement with previous in vitro experiments and confirm the sensitivity of the test. The effect of welding fume particles in this in vivo system suggests a potential risk for humans directly exposed to welding fumes."
1234018,Pickering 1980,Chronic toxicity of hexavalent chromium to the fathead minnow (Pimephales promelas),"The chronic effects of hexavalent chromium on the fathead minnow (Pimephales promelas) were investigated. Survival was affected only at the high test concentration of 3.95 mg Cr/L. All chromium concentrations, including 0.018 mg/L, the lowest tested, retarded the early growth of first-generation fish, but this effect was only temporary. Growth of second-generation fish was not affected at concentreations of 1.0 mg/L or lower. Reproduction and hatchability of eggs were not affected at any chromium concentration tested. The maximum acceptable toxicant concentration (MATC) for fathead minnows in hard water (209 mg/L as CaCO3 at pH 7.7) was based on survival and lies between 1.0 and 3.95 mg Cr/L, respectively. The application factor (MATC/96-hr LC50) is between 0.03 and 0.11.","Chronic toxicity of hexavalent chromium to the fathead minnow (Pimephales promelas) Abs: The chronic effects of hexavalent chromium on the fathead minnow (Pimephales promelas) were investigated. Survival was affected only at the high test concentration of 3.95 mg Cr/L. All chromium concentrations, including 0.018 mg/L, the lowest tested, retarded the early growth of first-generation fish, but this effect was only temporary. Growth of second-generation fish was not affected at concentreations of 1.0 mg/L or lower. Reproduction and hatchability of eggs were not affected at any chromium concentration tested. The maximum acceptable toxicant concentration (MATC) for fathead minnows in hard water (209 mg/L as CaCO3 at pH 7.7) was based on survival and lies between 1.0 and 3.95 mg Cr/L, respectively. The application factor (MATC/96-hr LC50) is between 0.03 and 0.11."
1234017,Norseth 1980,Cancer hazards caused by nickel and chromium exposure,"An increased risk of cancer associated with nickel refining and with chromate production has been known for some decades. The occupational exposure pattern of both nickel and chromium is very complex. Even though nickel carbonyl is an experimental carcinogen, there are no data supporting its carcinogenicity in humans. Nickel subsulfide may be the most potent carcinogen among the different nickel compounds. A correlation between lung cancer and exposure to chromates has been shown in several studies. As yet, there are no epidemiologic data indicating carcinogenicity of chromium(III) salts. Hexavalent chromium, however, has been suggested as the causative carcinogen among platers and ferrochromium workers. There is an urgent need for careful dose registration before a quantitative cancer risk analysis can be performed for the nickel and chromium industry.","Cancer hazards caused by nickel and chromium exposure Abs: An increased risk of cancer associated with nickel refining and with chromate production has been known for some decades. The occupational exposure pattern of both nickel and chromium is very complex. Even though nickel carbonyl is an experimental carcinogen, there are no data supporting its carcinogenicity in humans. Nickel subsulfide may be the most potent carcinogen among the different nickel compounds. A correlation between lung cancer and exposure to chromates has been shown in several studies. As yet, there are no epidemiologic data indicating carcinogenicity of chromium(III) salts. Hexavalent chromium, however, has been suggested as the causative carcinogen among platers and ferrochromium workers. There is an urgent need for careful dose registration before a quantitative cancer risk analysis can be performed for the nickel and chromium industry."
1234013,Norseth 1981,The carcinogenicity of chromium,"The carcinogenicity of chromium compounds is reviewed with specific attention to the gaps in knowledge for risk estimation and research needs. The most important problems at present are whether trivalent chromium compounds cause cancer, and whether there is a difference in cancer causing effects between the soluble and the slightly soluble hexavalent compounds in the practical exposure situation. Dose estimates for risk estimation based on epidemiological investigations are also lacking. Present evidence indicates that the trivalent chromium compounds do not cause cancer although high concentrations in some in vitro systems have shown genetic toxicity. Hexavalent chromium compounds cause cancer in humans, in experimental animals and exert genetic toxicity in bacteria and in mammalian cells in vitro. Epidemiological evidence and animal experiments indicate that the slightly soluble hexavalent salts are the most potent carcinogens, but proper identification and characterization of exposure patterns in epidemiological work are lacking. Workers also tend to have mixed exposures. Soluble and slightly soluble salts are equally potent genotoxic agents in vitro. Further work for establishing dose estimates for risk evaluation in epidemiological work is important. In vitro systems should be applied for further identification of the mechanism of the carcinogenic effects, and animal experiments are urgent for comparison of the carcinogenic potency of the different hexavalent salts. Hexavalent chromium salts must be regarded as established carcinogens, and proper action should be taken in all industries with regard to such exposure. At present the carcinogenic risk to the general population caused by chromium compounds seems to be negligible, chromium in cigarettes, however, is an uncertainty in this respect. The amount of chromium and the type of chromium compounds inhaled from cigarettes is not known.","The carcinogenicity of chromium Abs: The carcinogenicity of chromium compounds is reviewed with specific attention to the gaps in knowledge for risk estimation and research needs. The most important problems at present are whether trivalent chromium compounds cause cancer, and whether there is a difference in cancer causing effects between the soluble and the slightly soluble hexavalent compounds in the practical exposure situation. Dose estimates for risk estimation based on epidemiological investigations are also lacking. Present evidence indicates that the trivalent chromium compounds do not cause cancer although high concentrations in some in vitro systems have shown genetic toxicity. Hexavalent chromium compounds cause cancer in humans, in experimental animals and exert genetic toxicity in bacteria and in mammalian cells in vitro. Epidemiological evidence and animal experiments indicate that the slightly soluble hexavalent salts are the most potent carcinogens, but proper identification and characterization of exposure patterns in epidemiological work are lacking. Workers also tend to have mixed exposures. Soluble and slightly soluble salts are equally potent genotoxic agents in vitro. Further work for establishing dose estimates for risk evaluation in epidemiological work is important. In vitro systems should be applied for further identification of the mechanism of the carcinogenic effects, and animal experiments are urgent for comparison of the carcinogenic potency of the different hexavalent salts. Hexavalent chromium salts must be regarded as established carcinogens, and proper action should be taken in all industries with regard to such exposure. At present the carcinogenic risk to the general population caused by chromium compounds seems to be negligible, chromium in cigarettes, however, is an uncertainty in this respect. The amount of chromium and the type of chromium compounds inhaled from cigarettes is not known."
1234012,Pashin et al. 1981,[Complex trial of the genetic activity of the hexavalent chromium ion in vitro and in vivo],HEEP COPYRIGHT: BIOL ABS. Mutagenic activity of K2Cr2O7 is studied in experiments in vitro on the Chinese hamster V-79 somatic cell culture. In vivo tests showed no significant increase in the number of dominant lethals and chromosome aberrations in the mouse bone marrow cells after a single i.p. injection.,[Complex trial of the genetic activity of the hexavalent chromium ion in vitro and in vivo] Abs: HEEP COPYRIGHT: BIOL ABS. Mutagenic activity of K2Cr2O7 is studied in experiments in vitro on the Chinese hamster V-79 somatic cell culture. In vivo tests showed no significant increase in the number of dominant lethals and chromosome aberrations in the mouse bone marrow cells after a single i.p. injection.
1234009,Carelli et al. 1981,Interferences in the spectrophotometric S-diphenylcarbazide determination of environmental hexavalent chromium in a chromium and zinc plating plant,"A study on the determination of environmental hexavalent chromium [Cr(VI)] was carried out in a chromium and zinc plating plant. The atmospheric particulate was collected both on glass wool filters and with an electrostatic sampler; Cr(VI) was determined by the S-diphenylcarbazide method. The filtered and electrostatically collected Cr(VI) was extracted with both 1.4% sulfuric acid and 7% sodium carbonate. Strong interference was observed when extraction was carried out with the acid medium. Alkaline extraction permits 95 +/- 6 (+/- SD)% recovery of the total chromium and has been shown to be suitable in releasing Cr(VI). The analyses of the alkaline samples were carried out with the standard addition method to compensate for a depressive interference of 26 +/- 8 (+/- SD)%. The absorbance decrease of the Cr-S-diphenylcarbazide complex is a time function, and it should be measured within a few minutes of the reagent addition.","Interferences in the spectrophotometric S-diphenylcarbazide determination of environmental hexavalent chromium in a chromium and zinc plating plant Abs: A study on the determination of environmental hexavalent chromium [Cr(VI)] was carried out in a chromium and zinc plating plant. The atmospheric particulate was collected both on glass wool filters and with an electrostatic sampler; Cr(VI) was determined by the S-diphenylcarbazide method. The filtered and electrostatically collected Cr(VI) was extracted with both 1.4% sulfuric acid and 7% sodium carbonate. Strong interference was observed when extraction was carried out with the acid medium. Alkaline extraction permits 95 +/- 6 (+/- SD)% recovery of the total chromium and has been shown to be suitable in releasing Cr(VI). The analyses of the alkaline samples were carried out with the standard addition method to compensate for a depressive interference of 26 +/- 8 (+/- SD)%. The absorbance decrease of the Cr-S-diphenylcarbazide complex is a time function, and it should be measured within a few minutes of the reagent addition."
1234008,White et al. 1981,Response of a human tumour cell line to chronic potassium dichromate exposure,"Cultures of the human cell line NHIK 3025 were exposed over an 18-month period to 0.5 mumol/1 potassium dichromate (K2Cr2O7) containing 1 mumol/1 hexavalent chromium. The chronically exposed cells increased their tolerance to K2Cr2O7 in comparison to control populations. The doubling time of the chronically exposed cell populations increased even in the absence of K2Cr2O7, but they did not change their morphology (light level), nor contain as many giant cells as newly exposed control populations. Cells returned to control medium for 6 months after 12-months exposure to K2Cr2O7 showed a gradual but incomplete reversal of these effects. The results are compared with those obtained from cells of non-tumour origin.","Response of a human tumour cell line to chronic potassium dichromate exposure Abs: Cultures of the human cell line NHIK 3025 were exposed over an 18-month period to 0.5 mumol/1 potassium dichromate (K2Cr2O7) containing 1 mumol/1 hexavalent chromium. The chronically exposed cells increased their tolerance to K2Cr2O7 in comparison to control populations. The doubling time of the chronically exposed cell populations increased even in the absence of K2Cr2O7, but they did not change their morphology (light level), nor contain as many giant cells as newly exposed control populations. Cells returned to control medium for 6 months after 12-months exposure to K2Cr2O7 showed a gradual but incomplete reversal of these effects. The results are compared with those obtained from cells of non-tumour origin."
1234007,Rytter and  Haustein 1982,Hapten conjugation in the leucocyte migration inhibition test in allergic chromate eczema,"We studied the in vitro conjugation of chromium salts and found that trivalent chromium binds to protein 10 times more strongly than hexavalent chromium. We also investigated the use of two different lymphocyte migration inhibition tests for the diagnosis of chromium allergy. The capillary method proved superior to the Clausen technique, and potassium dichromate was shown to be a better antigen than chromium chloride. The test results correlated well with standard patch tests and we recommend the capillary method for the investigation of difficult cases of suspected chromium allergy.","Hapten conjugation in the leucocyte migration inhibition test in allergic chromate eczema Abs: We studied the in vitro conjugation of chromium salts and found that trivalent chromium binds to protein 10 times more strongly than hexavalent chromium. We also investigated the use of two different lymphocyte migration inhibition tests for the diagnosis of chromium allergy. The capillary method proved superior to the Clausen technique, and potassium dichromate was shown to be a better antigen than chromium chloride. The test results correlated well with standard patch tests and we recommend the capillary method for the investigation of difficult cases of suspected chromium allergy."
1234006,Babich et al. 1982,Comparative toxicity of trivalent and hexavalent chromium to fungi,,Comparative toxicity of trivalent and hexavalent chromium to fungi Abs: 
1234005,Sastry and  Tyagi 1982,"Toxic effects of chromium in a freshwater teleost fish, Channa punctatus","The effect of in vivo exposure to a sublethal concentration of hexavalent chromium for 30 days on blood glucose, blood liver and muscle lactic acid; haemoglobin, liver and muscle glycogen; and activities of lactate dehydrogenase (LDH), pyruvate dehydrogenase (PHD) and succinate dehydrogenase (SDH) in liver, muscle, kidney, gills and brain has been studied. Blood glucose and lactic acid levels were elevated. Liver glycogen was depleted but muscle glycogen content increase. The activities of LDH and SDH in liver were elevate. Elevation was also observed in muscle LDH and PDH activities, showing that the rate of glycolysis is increased. No change was noted in haemoglobin content of blood or in the activities of the three dehydrogenases in kidney and gills.","Toxic effects of chromium in a freshwater teleost fish, Channa punctatus Abs: The effect of in vivo exposure to a sublethal concentration of hexavalent chromium for 30 days on blood glucose, blood liver and muscle lactic acid; haemoglobin, liver and muscle glycogen; and activities of lactate dehydrogenase (LDH), pyruvate dehydrogenase (PHD) and succinate dehydrogenase (SDH) in liver, muscle, kidney, gills and brain has been studied. Blood glucose and lactic acid levels were elevated. Liver glycogen was depleted but muscle glycogen content increase. The activities of LDH and SDH in liver were elevate. Elevation was also observed in muscle LDH and PDH activities, showing that the rate of glycolysis is increased. No change was noted in haemoglobin content of blood or in the activities of the three dehydrogenases in kidney and gills."
1234004,White et al. 1982,Biochemical studies of rat lung following exposure to potassium dichromate or chromium-rich welding fume particles,"Rats were examined for biochemical changes at the lung surface and in lung tissue 1, 4, and 13 weeks after a single instillation of the soluble of insoluble fraction of stainless steel welding particles, or potassium dichromate containing concentrations of hexavalent chromium (CrVI) equivalent to those found in the welding particles. Most of the toxicity of the welding particles 1 week after instillation could be related to the content of soluble CrVI, though the insoluble particles also produced changes at the alveolar surface. The regression of inflammatory changes 4 and 13 weeks after instillation was probably due to the removal of soluble components such as CrVI from the lung.","Biochemical studies of rat lung following exposure to potassium dichromate or chromium-rich welding fume particles Abs: Rats were examined for biochemical changes at the lung surface and in lung tissue 1, 4, and 13 weeks after a single instillation of the soluble of insoluble fraction of stainless steel welding particles, or potassium dichromate containing concentrations of hexavalent chromium (CrVI) equivalent to those found in the welding particles. Most of the toxicity of the welding particles 1 week after instillation could be related to the content of soluble CrVI, though the insoluble particles also produced changes at the alveolar surface. The regression of inflammatory changes 4 and 13 weeks after instillation was probably due to the removal of soluble components such as CrVI from the lung."
1234003,van der Putte et al. 1982,Effects of hexavalent chromium in rainbow trout (Salmo gairdneri) after prolonged exposure at two different pH levels,,Effects of hexavalent chromium in rainbow trout (Salmo gairdneri) after prolonged exposure at two different pH levels Abs: 
1234000,Bianchi et al. 1982,Effects of hexavalent chromium on the adenylate pool of hamster fibroblasts,"The mechanisms through which Cr(VI) reduces the intracellular levels of ATP in hamster fibroblasts (BHK 21 line) were investigated. Leakage of pool components during treatment of cells prelabelled with [3H]adenosine was examined. Adenylate pool composition was analyzed by thin-layer chromatography (TLC) in cells incubated with [3H]adenosine immediately after treatment with Cr(VI), and the endogenous concentrations of different nucleotides were determined by high-performance liquid chromatography (HPLC). Interference of Cr(VI) with different steps of ATP biosynthesis could be assessed. Treated cells showed increased loss of radioactive hypoxanthine and inosine in the treatment medium, but no nucleotides were detected outside the cells. A marked unbalance of the endogenous adenylate pool was produced by chromium, consisting in a strong decrease of ATP, accompanied by a very pronounced increase of ADP and AMP. Treatment with Cr(VI) caused an altered distribution of label among the different adenylate pool components, especially an accumulation of radioactivity in the ADP and AMP fractions. Also other effects on the soluble pool were detected by HPLC analysis, namely the reduction of NAD content and variations in the guanylate pool which closely paralleled the ones observed in the adenylate pool. Energy charge values, calculates on the basis of HPLC and TLC data, allowed to detect a specific inhibition of ADP phosphorylation to ATP. An interference with the early steps of adenylate synthesis could be inferred from the enhanced amounts of hypoxanthine and inosine in the treated cultures.","Effects of hexavalent chromium on the adenylate pool of hamster fibroblasts Abs: The mechanisms through which Cr(VI) reduces the intracellular levels of ATP in hamster fibroblasts (BHK 21 line) were investigated. Leakage of pool components during treatment of cells prelabelled with [3H]adenosine was examined. Adenylate pool composition was analyzed by thin-layer chromatography (TLC) in cells incubated with [3H]adenosine immediately after treatment with Cr(VI), and the endogenous concentrations of different nucleotides were determined by high-performance liquid chromatography (HPLC). Interference of Cr(VI) with different steps of ATP biosynthesis could be assessed. Treated cells showed increased loss of radioactive hypoxanthine and inosine in the treatment medium, but no nucleotides were detected outside the cells. A marked unbalance of the endogenous adenylate pool was produced by chromium, consisting in a strong decrease of ATP, accompanied by a very pronounced increase of ADP and AMP. Treatment with Cr(VI) caused an altered distribution of label among the different adenylate pool components, especially an accumulation of radioactivity in the ADP and AMP fractions. Also other effects on the soluble pool were detected by HPLC analysis, namely the reduction of NAD content and variations in the guanylate pool which closely paralleled the ones observed in the adenylate pool. Energy charge values, calculates on the basis of HPLC and TLC data, allowed to detect a specific inhibition of ADP phosphorylation to ATP. An interference with the early steps of adenylate synthesis could be inferred from the enhanced amounts of hypoxanthine and inosine in the treated cultures."
1233999,Bianchi 1982,Nucleotide pool unbalance induced in cultured cells by treatments with different chemicals,"Intracellular nucleotide pools directly influence a great number of cellular activities, and their size and composition are easily altered by chemical agents. However, they are seldom examined when chemical toxicity is investigated. The importance of evaluating the effects produced at the nucleotide pool level is also discussed. Some examples are reported in which the activity of a tested chemical on nucleic acid metabolism could be detected only by taking into account the modifications induced in the precursor pool. One example is the case of hexavalent chromium, which inhibits DNA and RNA syntheses, but also affects the uptake of exogenous nucleosides, thus modifying the labelling pattern of nucleic acids in treated cells. A similar situation is observed with alkylating agents (e.g. MMS and EMS), whose induction of DNA repair synthesis is sometimes masked by the concomitant depletion of labelled nucleotides in the intracellular pool.","Nucleotide pool unbalance induced in cultured cells by treatments with different chemicals Abs: Intracellular nucleotide pools directly influence a great number of cellular activities, and their size and composition are easily altered by chemical agents. However, they are seldom examined when chemical toxicity is investigated. The importance of evaluating the effects produced at the nucleotide pool level is also discussed. Some examples are reported in which the activity of a tested chemical on nucleic acid metabolism could be detected only by taking into account the modifications induced in the precursor pool. One example is the case of hexavalent chromium, which inhibits DNA and RNA syntheses, but also affects the uptake of exogenous nucleosides, thus modifying the labelling pattern of nucleic acids in treated cells. A similar situation is observed with alkylating agents (e.g. MMS and EMS), whose induction of DNA repair synthesis is sometimes masked by the concomitant depletion of labelled nucleotides in the intracellular pool."
1233998,Jakobsen and  Eik-Nes 1982,Hexavalent chromium and ascorbic acid interaction on proliferation of the human cell line NHIK3025,"When cells from the human cell line NHIK3025 were cultured for 4 days, with hexavalent chromium (K2Cr2O7) at a concentration of 8 . 10(-7)M, the relative cell number was reduced to 38%. This effect of hexavalent chromium was abolished if ascorbic acid and chromate were added simultaneously to the incubation medium, but not if ascorbic acid was added 24 h prior to chromate addition. Dehydroascorbic acid was not able to reduce the effect of K2Cr2O7 either when added simultaneously or when added 24 h prior to chromate exposure. Therefore, the cells could only be protected against the toxic effect of hexavalent chromium when ascorbic acid was added at the same time as K2Cr2O7.","Hexavalent chromium and ascorbic acid interaction on proliferation of the human cell line NHIK3025 Abs: When cells from the human cell line NHIK3025 were cultured for 4 days, with hexavalent chromium (K2Cr2O7) at a concentration of 8 . 10(-7)M, the relative cell number was reduced to 38%. This effect of hexavalent chromium was abolished if ascorbic acid and chromate were added simultaneously to the incubation medium, but not if ascorbic acid was added 24 h prior to chromate addition. Dehydroascorbic acid was not able to reduce the effect of K2Cr2O7 either when added simultaneously or when added 24 h prior to chromate exposure. Therefore, the cells could only be protected against the toxic effect of hexavalent chromium when ascorbic acid was added at the same time as K2Cr2O7."
1233997,Samsoen et al. 1982,Patch testing with hexavalent chromium salts in different vehicles and with nickel and cobalt in petrolatum,"In approaching the question as to which test preparations are most suitable for patch testing of metals, 25 chromium sensitive patients were tested with 0.5% potassium dichromate either in water or petrolatum. The aqueous solution proved better than the petrolatum preparation at a 48 h reading with Neodermtest Roc. No difference in sensitivity was recorded between 4 hexavalent chromium salts. 3 patients who were only sensitive to chromium solution in water also reacted positively to a 1% cobalt chloride solution and a 5% nickel sulfate solution in petrolatum.","Patch testing with hexavalent chromium salts in different vehicles and with nickel and cobalt in petrolatum Abs: In approaching the question as to which test preparations are most suitable for patch testing of metals, 25 chromium sensitive patients were tested with 0.5% potassium dichromate either in water or petrolatum. The aqueous solution proved better than the petrolatum preparation at a 48 h reading with Neodermtest Roc. No difference in sensitivity was recorded between 4 hexavalent chromium salts. 3 patients who were only sensitive to chromium solution in water also reacted positively to a 1% cobalt chloride solution and a 5% nickel sulfate solution in petrolatum."
1233994,Moreton et al. 1983,"Investigation of techniques for the analysis of hexavalent chromium, total chromium and total nickel in welding fume: a co-operative study",Studied were: an s-diphenylcarbazide colour method for Cr (VI); a perchloric acid method for total Cr; atomic absorption spectrophotometry for total Cr; analysis for total Ni. Good results were obtained with the methods tested. Details of sensitivity and detection limits are given. 1mg samples meet the requirements of existing TLVs. Sampling methods are discussed. Analytical procedures are described.,"Investigation of techniques for the analysis of hexavalent chromium, total chromium and total nickel in welding fume: a co-operative study Abs: Studied were: an s-diphenylcarbazide colour method for Cr (VI); a perchloric acid method for total Cr; atomic absorption spectrophotometry for total Cr; analysis for total Ni. Good results were obtained with the methods tested. Details of sensitivity and detection limits are given. 1mg samples meet the requirements of existing TLVs. Sampling methods are discussed. Analytical procedures are described."
1233992,Bennicelli et al. 1983,High sensitivity of Salmonella TA102 in detecting hexavalent chromium mutagenicity and its reversal by liver and lung preparations,"The recently developed strain TA102, particularly suited to the detection of oxidative mutagens (Levin et al., 1983), was the most sensitive out of 9 strains of S. typhimurium his- in revealing the mutagenicity of Cr(VI) compounds (sodium dichromate, calcium chromate and chromium trioxide). The rank of sensitivity was the following: TA102, TA100, TA97, TA92, TA1978, TA98, TA1538 and TA1537, TA1535 being the only insensitive strain. Cr(III) compounds (chromic acetate, chromic nitrate and chromic potassium sulfate) were totally inactive with all strains. The direct mutagenicity of Cr(VI) was markedly decreased, through NADPH-requiring mechanisms, by rat-liver S9 fractions and, to a lower extent, by human lung S12 fractions, which supports the hypothesis of a metabolically regulated threshold in chromium pulmonary carcinogenicity.","High sensitivity of Salmonella TA102 in detecting hexavalent chromium mutagenicity and its reversal by liver and lung preparations Abs: The recently developed strain TA102, particularly suited to the detection of oxidative mutagens (Levin et al., 1983), was the most sensitive out of 9 strains of S. typhimurium his- in revealing the mutagenicity of Cr(VI) compounds (sodium dichromate, calcium chromate and chromium trioxide). The rank of sensitivity was the following: TA102, TA100, TA97, TA92, TA1978, TA98, TA1538 and TA1537, TA1535 being the only insensitive strain. Cr(III) compounds (chromic acetate, chromic nitrate and chromic potassium sulfate) were totally inactive with all strains. The direct mutagenicity of Cr(VI) was markedly decreased, through NADPH-requiring mechanisms, by rat-liver S9 fractions and, to a lower extent, by human lung S12 fractions, which supports the hypothesis of a metabolically regulated threshold in chromium pulmonary carcinogenicity."
1233991,Pedersen et al. 1983,Detection by replica plating of false revertant colonies induced in the Salmonella-mammalian microsome assay by hexavalent chromium,"The replica plating method as developed by Lederberg has been used to differentiate between &quot;true&quot; and &quot;false&quot; histidine-requiring revertant bacterial colonies which develop on minimal agar plates in the Ames test. Strains of S. typhimurium LT2, TA 100, when exposed to either sodium dichromate or the fumes from the welding of stainless steel, develop colonies whose apparent numbers are directly in proportion to the Cr(VI) content per plate in both cases, over a wide dose range. Replica impressions of the resulting colonies were transferred to Vogel Bonner minimal agar plates and incubated for 48 hr at 37 degrees C. It was then observed that considerable numbers of &quot;false&quot; revertant colonies were obtained at those Cr(VI) doses which resulted in a pronounced toxic effect, albeit with an acceptable level of the bacterial background lawn. No morphological distinction between &quot;true&quot; and &quot;false&quot; revertant colonies could be made. Although it would appear that at low doses (i.e., low toxicity) the true mutagenicity of stainless steel welding fumes can be completely accounted for by the presence of Cr(VI), the dose range over which the mutagenicity assay is reliable cannot be estimated from examination of the background lawn or from an estimate of the degree of survival of the treated cultures. Thus there is raised a serious question concerning the reliability of quantitative data published in bacterial mutagenicity testing where replica testing of the histidine requirement of the resulting &quot;revertant&quot; colonies is not routinely made. It is suggested that the replica technique can easily be developed as a simple and useful tool for the control of histidine requirement and ampicillin resistance in routine mutagenicity testing.(ABSTRACT TRUNCATED AT 250 WORDS)","Detection by replica plating of false revertant colonies induced in the Salmonella-mammalian microsome assay by hexavalent chromium Abs: The replica plating method as developed by Lederberg has been used to differentiate between &quot;true&quot; and &quot;false&quot; histidine-requiring revertant bacterial colonies which develop on minimal agar plates in the Ames test. Strains of S. typhimurium LT2, TA 100, when exposed to either sodium dichromate or the fumes from the welding of stainless steel, develop colonies whose apparent numbers are directly in proportion to the Cr(VI) content per plate in both cases, over a wide dose range. Replica impressions of the resulting colonies were transferred to Vogel Bonner minimal agar plates and incubated for 48 hr at 37 degrees C. It was then observed that considerable numbers of &quot;false&quot; revertant colonies were obtained at those Cr(VI) doses which resulted in a pronounced toxic effect, albeit with an acceptable level of the bacterial background lawn. No morphological distinction between &quot;true&quot; and &quot;false&quot; revertant colonies could be made. Although it would appear that at low doses (i.e., low toxicity) the true mutagenicity of stainless steel welding fumes can be completely accounted for by the presence of Cr(VI), the dose range over which the mutagenicity assay is reliable cannot be estimated from examination of the background lawn or from an estimate of the degree of survival of the treated cultures. Thus there is raised a serious question concerning the reliability of quantitative data published in bacterial mutagenicity testing where replica testing of the histidine requirement of the resulting &quot;revertant&quot; colonies is not routinely made. It is suggested that the replica technique can easily be developed as a simple and useful tool for the control of histidine requirement and ampicillin resistance in routine mutagenicity testing.(ABSTRACT TRUNCATED AT 250 WORDS)"
1233990,Luli et al. 1983,Hexavalent chromium-resistant bacteria isolated from river sediments,"Hexavalent chromium [Cr(VI)] is a known carcinogen and mutagen; however, the actual mechanisms of Cr toxicity are unknown. Two approaches were used to isolate Cr(VI)-resistant bacteria from metal-contaminated river sediments. Diluted sediments were plated directly onto a peptone-yeast extract (PYE) medium containing 0 to 100 micrograms of Cr(VI) ml-1. Approximately 8.4 x 10(5) CFU g-1 were recovered on 0 microgram of Cr(VI) ml-1, whereas 4.0 x 10(2) CFU g-1 were recovered on PYE plus 100 micrograms of Cr(VI) ml-1. Alternatively, continuous culture enrichment techniques were employed using PYE and 100 micrograms Cr(VI) ml-1 input at dilution rates of 0.02 and 0.10 h-1. After six residence periods, 10(9) CFU were recovered on PYE agar containing 0 microgram of Cr(VI) ml-1 and 10(7) CFU on PYE agar plus 100 micrograms of Cr(VI) ml-1. Of 89 isolates obtained by direct plating onto PYE, 47% were resistant to 100 micrograms of Cr(VI) ml-1, and 29% were resistant to 250 micrograms of Cr(VI) ml-1. When the same isolates were plated onto PYE containing Cr(III), 88% were resistant to 100 micrograms ml-1 but only 2% were resistant to 250 micrograms ml-1. Cr, Co, Sb, and Zn were found in significantly higher concentrations at an industry-related contaminated site than at a site 11 km downstream. Total Cr in the sediments at the contaminated site averaged 586 micrograms (dry weight) g-1, and the downstream site averaged 71 micrograms (dry weight) g-1. The Cr recovered from acid-digested Ottawa River sediment samples was predominantly hexavalent. Five acid digestion procedures followed by atomic absorption spectroscopy were compared and found to be 30 to 70% efficient for recovery of Cr relative to neutron activation analysis. A population of aerobic, heterotrophic bacteria was recovered from sediments containing elevated levels of Cr.(ABSTRACT TRUNCATED AT 250 WORDS)","Hexavalent chromium-resistant bacteria isolated from river sediments Abs: Hexavalent chromium [Cr(VI)] is a known carcinogen and mutagen; however, the actual mechanisms of Cr toxicity are unknown. Two approaches were used to isolate Cr(VI)-resistant bacteria from metal-contaminated river sediments. Diluted sediments were plated directly onto a peptone-yeast extract (PYE) medium containing 0 to 100 micrograms of Cr(VI) ml-1. Approximately 8.4 x 10(5) CFU g-1 were recovered on 0 microgram of Cr(VI) ml-1, whereas 4.0 x 10(2) CFU g-1 were recovered on PYE plus 100 micrograms of Cr(VI) ml-1. Alternatively, continuous culture enrichment techniques were employed using PYE and 100 micrograms Cr(VI) ml-1 input at dilution rates of 0.02 and 0.10 h-1. After six residence periods, 10(9) CFU were recovered on PYE agar containing 0 microgram of Cr(VI) ml-1 and 10(7) CFU on PYE agar plus 100 micrograms of Cr(VI) ml-1. Of 89 isolates obtained by direct plating onto PYE, 47% were resistant to 100 micrograms of Cr(VI) ml-1, and 29% were resistant to 250 micrograms of Cr(VI) ml-1. When the same isolates were plated onto PYE containing Cr(III), 88% were resistant to 100 micrograms ml-1 but only 2% were resistant to 250 micrograms ml-1. Cr, Co, Sb, and Zn were found in significantly higher concentrations at an industry-related contaminated site than at a site 11 km downstream. Total Cr in the sediments at the contaminated site averaged 586 micrograms (dry weight) g-1, and the downstream site averaged 71 micrograms (dry weight) g-1. The Cr recovered from acid-digested Ottawa River sediment samples was predominantly hexavalent. Five acid digestion procedures followed by atomic absorption spectroscopy were compared and found to be 30 to 70% efficient for recovery of Cr relative to neutron activation analysis. A population of aerobic, heterotrophic bacteria was recovered from sediments containing elevated levels of Cr.(ABSTRACT TRUNCATED AT 250 WORDS)"
1233989,Al-Tawil et al. 1983,Lymphocyte stimulation by trivalent and hexavalent chromium compounds in patients with chromium sensitivity. An aid to diagnosis,"Peripheral blood lymphocytes from 31 patients with a positive patch test to potassium dichromate (K2Cr2O7) and from 24 healthy controls were stimulated with various concentrations of chromium chloride (CrCl3) and/or chromium basic sulphate (Cr4(SO4)5(OH)2), sodium chromate (Na2CrO4) or K2Cr2O7 on various days of culture. Both trivalent and hexavalent chromium compounds could induce lymphocyte transformation, as measured by increased DNA synthesis. The response occurred in the T-enriched population and was monocyte dependent. Lymphocytes from 11 of these patients could not be stimulated with the chromium compounds in vitro, whereas the in vivo serial dilution test (SDT) was positive in 4 and negative in 7 of them. Lymphocytes from 2 patients with a negative in vivo SDT showed a positive response in vitro. The strength of the in vivo SDT results did not correlate well with the height of in vitro responses. The DNA synthesis test seems to be a reliable in vitro method to aid in the diagnosis of chromium sensitivity.","Lymphocyte stimulation by trivalent and hexavalent chromium compounds in patients with chromium sensitivity. An aid to diagnosis Abs: Peripheral blood lymphocytes from 31 patients with a positive patch test to potassium dichromate (K2Cr2O7) and from 24 healthy controls were stimulated with various concentrations of chromium chloride (CrCl3) and/or chromium basic sulphate (Cr4(SO4)5(OH)2), sodium chromate (Na2CrO4) or K2Cr2O7 on various days of culture. Both trivalent and hexavalent chromium compounds could induce lymphocyte transformation, as measured by increased DNA synthesis. The response occurred in the T-enriched population and was monocyte dependent. Lymphocytes from 11 of these patients could not be stimulated with the chromium compounds in vitro, whereas the in vivo serial dilution test (SDT) was positive in 4 and negative in 7 of them. Lymphocytes from 2 patients with a negative in vivo SDT showed a positive response in vitro. The strength of the in vivo SDT results did not correlate well with the height of in vitro responses. The DNA synthesis test seems to be a reliable in vitro method to aid in the diagnosis of chromium sensitivity."
1233988,Allenby and  Goodwin 1983,Influence of detergent washing powders on minimal eliciting patch test concentrations of nickel and chromium,"Minimum eliciting levels of nickel have been estimated in 25 nickel-sensitive subjects, and of chromium in 14 chromium-sensitive subjects by patch tests with aqueous solutions of the respective metals. The minimum level of each metal required to provoke a patch test reaction was considerably greater than that found in fabric washing powder solutions and was in the majority of patients tested of the order of 112 ppm nickel (0.05% nickel sulphate) or 885 ppm hexavalent chromium (0.25% potassium dichromate). One nickel-sensitive subject and one chromium-sensitive subject reacted to 1 ppm of the respective metal. Fabric washing powder did not significantly alter the patch test reaction to nickel sulphate or provoke reactions in nickel- or chromium-sensitive subjects. EDTA significantly reduced the number and severity of patch test reactions to nickel sulphate but not those to potassium dichromate or trivalent chromium.","Influence of detergent washing powders on minimal eliciting patch test concentrations of nickel and chromium Abs: Minimum eliciting levels of nickel have been estimated in 25 nickel-sensitive subjects, and of chromium in 14 chromium-sensitive subjects by patch tests with aqueous solutions of the respective metals. The minimum level of each metal required to provoke a patch test reaction was considerably greater than that found in fabric washing powder solutions and was in the majority of patients tested of the order of 112 ppm nickel (0.05% nickel sulphate) or 885 ppm hexavalent chromium (0.25% potassium dichromate). One nickel-sensitive subject and one chromium-sensitive subject reacted to 1 ppm of the respective metal. Fabric washing powder did not significantly alter the patch test reaction to nickel sulphate or provoke reactions in nickel- or chromium-sensitive subjects. EDTA significantly reduced the number and severity of patch test reactions to nickel sulphate but not those to potassium dichromate or trivalent chromium."
1233987,Hewitt and  Gray 1983,Some difficulties in the assessment of electric arc welding fume,"During electric arc welding of metals, particulate fume in a variety of chemical compositions and physical forms is produced with consequent complex solution chemistry. Mechanisms of fume formation include condensation of vaporized metals to produce submicron diameter chains, and spatter of larger particles with subsequent oxidation to yield mixed metal oxide fumes in the respirable range. Complete dissolution of certain constituent metals such as chromium, can be achieved by fusion with potassium hydrogen sulphate. Extraction of hexavalent chromium by sodium carbonate/hydroxide solution is efficient and rapid, while some other extractants give erroneous results. Investigations show that constituent metals are released from the fume at different rates both in vitro and in vivo. The implications arising from the complex nature of welding fume for industrial hygiene assessment are discussed.","Some difficulties in the assessment of electric arc welding fume Abs: During electric arc welding of metals, particulate fume in a variety of chemical compositions and physical forms is produced with consequent complex solution chemistry. Mechanisms of fume formation include condensation of vaporized metals to produce submicron diameter chains, and spatter of larger particles with subsequent oxidation to yield mixed metal oxide fumes in the respirable range. Complete dissolution of certain constituent metals such as chromium, can be achieved by fusion with potassium hydrogen sulphate. Extraction of hexavalent chromium by sodium carbonate/hydroxide solution is efficient and rapid, while some other extractants give erroneous results. Investigations show that constituent metals are released from the fume at different rates both in vitro and in vivo. The implications arising from the complex nature of welding fume for industrial hygiene assessment are discussed."
1233986,Galvin and  Oberg 1984,Toxicity of hexavalent chromium to the alveolar macrophage in vivo and in vitro,"In vivo and in vitro systems were used to evaluate hexavalent chromium toxicity to alveolar macrophages. Rat alveolar macrophages were exposed to 2 micrograms calcium chromate (CaCrO4, insoluble) or 2 micrograms chromium trioxide (CrO3, soluble) in live animals, in vivo, and in tissue culture, in vitro, collected by lavage from the lung. Chemiluminescence and oxygen consumption were measured as indicators of toxicity. Trypan blue dye exclusion was used to determine macrophage viability. In vivo exposure of the macrophage to either chromium compound showed no toxic effects at a 2-micrograms dose. Macrophages exposed in tissue culture, however, had values significantly different from controls. The untreated controls for both exposure methods were compared to evaluate differences resulting from methods alone.","Toxicity of hexavalent chromium to the alveolar macrophage in vivo and in vitro Abs: In vivo and in vitro systems were used to evaluate hexavalent chromium toxicity to alveolar macrophages. Rat alveolar macrophages were exposed to 2 micrograms calcium chromate (CaCrO4, insoluble) or 2 micrograms chromium trioxide (CrO3, soluble) in live animals, in vivo, and in tissue culture, in vitro, collected by lavage from the lung. Chemiluminescence and oxygen consumption were measured as indicators of toxicity. Trypan blue dye exclusion was used to determine macrophage viability. In vivo exposure of the macrophage to either chromium compound showed no toxic effects at a 2-micrograms dose. Macrophages exposed in tissue culture, however, had values significantly different from controls. The untreated controls for both exposure methods were compared to evaluate differences resulting from methods alone."
1233982,Ryberg and  Alexander 1984,Inhibitory action of hexavalent chromium (Cr(VI)) on the mitochondrial respiration and a possible coupling to the reduction of Cr(VI),"The reduction of hexavalent chromium (Cr(VI] in isolated liver mitochondria was studied under different redox conditions in the respiratory chain. With 25 microM Na2CrO4 the rates were 1.6 +/- 0.7, 13.9 +/- 0.6 and 12.7 +/- 0.7 nmole Cr(VI) reduced 15 min/mg protein with the electron transport chain oxidized, reduced and only complex 1 reduced respectively. Electrons from succinate, bypassing complex 1, were apparently unavailable for Cr(VI)-reduction. The kinetics of chromate reduction was studied with only complex 1 in a reduced state. A rapid and a slow phase were found, probably corresponding to different electron donors in the mitochondria. Blocking the free thiols with N-ethylmaleimide lead to less than 10% decrease in the rapid initial Cr(VI)-reduction and to about 20% decrease during the whole incubation period (15 min). The amounts of free thiols were moderately decreased (15%) in chromate treated mitochondria during the slow reduction of Cr(VI) only. SH-groups may thus participate as reductants during the slow reduction phase. The respiration rate was inhibited about 50% by 25 microM Na2CrO4 when the mitochondria oxidized NAD-linked substrates. In contrast, succinate stimulated respiration was inhibited 50% by 3.6 mM Na2CrO4. The observed inhibition was Na2CrO4 in the micromolar range was therefore probably localized at complex 1 and may be coupled to the reduction of Cr(VI) at the same place. The respiration of isolated hepatocytes was also affected by Na2CrO4. Five micromolar chromate caused 5-10% inhibition. The inhibitory action of chromate on the mitochondrial respiration may thus constitute an important cytotoxic mechanism.","Inhibitory action of hexavalent chromium (Cr(VI)) on the mitochondrial respiration and a possible coupling to the reduction of Cr(VI) Abs: The reduction of hexavalent chromium (Cr(VI] in isolated liver mitochondria was studied under different redox conditions in the respiratory chain. With 25 microM Na2CrO4 the rates were 1.6 +/- 0.7, 13.9 +/- 0.6 and 12.7 +/- 0.7 nmole Cr(VI) reduced 15 min/mg protein with the electron transport chain oxidized, reduced and only complex 1 reduced respectively. Electrons from succinate, bypassing complex 1, were apparently unavailable for Cr(VI)-reduction. The kinetics of chromate reduction was studied with only complex 1 in a reduced state. A rapid and a slow phase were found, probably corresponding to different electron donors in the mitochondria. Blocking the free thiols with N-ethylmaleimide lead to less than 10% decrease in the rapid initial Cr(VI)-reduction and to about 20% decrease during the whole incubation period (15 min). The amounts of free thiols were moderately decreased (15%) in chromate treated mitochondria during the slow reduction of Cr(VI) only. SH-groups may thus participate as reductants during the slow reduction phase. The respiration rate was inhibited about 50% by 25 microM Na2CrO4 when the mitochondria oxidized NAD-linked substrates. In contrast, succinate stimulated respiration was inhibited 50% by 3.6 mM Na2CrO4. The observed inhibition was Na2CrO4 in the micromolar range was therefore probably localized at complex 1 and may be coupled to the reduction of Cr(VI) at the same place. The respiration of isolated hepatocytes was also affected by Na2CrO4. Five micromolar chromate caused 5-10% inhibition. The inhibitory action of chromate on the mitochondrial respiration may thus constitute an important cytotoxic mechanism."
1233980,Bakke et al. 1984,Concentration-dependent effects of potassium dichromate on the cell cycle,"Hexavalent chromium is found to be a strong mutagen, and it also is a potential carcinogen in man. DNA flow cytometry, growth measurements, and determinations of mitotic index show that 1-2 microM K2Cr2O7 produces a prolongation of the G2 phase of the cell cycle in NHIK 3025 cells. By increasing the chromate concentrations (greater than 2 microM K2Cr2O7) the cells are also arrested in G2 phase. We have found, using synchronized cells and measuring cell cycle time, that the most chromate-sensitive part of the cell cycle is S phase. This phase is also somewhat prolonged, and the cells became arrested in early S phase at high toxic K2Cr2O7 concentrations (8 microM). Our results thus indicate that K2Cr2O7 has an effect within S phase--maybe on DNA/RNA synthesis--and also interferes with processes necessary for progression through the G2 phase.","Concentration-dependent effects of potassium dichromate on the cell cycle Abs: Hexavalent chromium is found to be a strong mutagen, and it also is a potential carcinogen in man. DNA flow cytometry, growth measurements, and determinations of mitotic index show that 1-2 microM K2Cr2O7 produces a prolongation of the G2 phase of the cell cycle in NHIK 3025 cells. By increasing the chromate concentrations (greater than 2 microM K2Cr2O7) the cells are also arrested in G2 phase. We have found, using synchronized cells and measuring cell cycle time, that the most chromate-sensitive part of the cell cycle is S phase. This phase is also somewhat prolonged, and the cells became arrested in early S phase at high toxic K2Cr2O7 concentrations (8 microM). Our results thus indicate that K2Cr2O7 has an effect within S phase--maybe on DNA/RNA synthesis--and also interferes with processes necessary for progression through the G2 phase."
1233977,Langerwerf et al. 1985,A comparison of the mutagenicity of soluble trivalent chromium compounds with that of potassium chromate,"The mutagenic potential of water soluble complexes of trivalent chromium with five different amino acids in Salmonella typhimurium strains TA92, TA94, TA98, and TA100 was studied. All complexes were nonmutagenic at concentrations up to 50 mumol/plate in the strains used. In contrast, trivalent chromium chloride was slightly mutagenic in TA98 and a considerable increase in numbers of revertants was observed in TA94. Hexavalent chromium was nonmutagenic in TA98. Strong mutagenic effects were found in TA92, TA94, and TA100. The large difference in mutagenicity between trivalent and hexavalent chromium is discussed with respect to affinity to extracellular phosphate, diffusability through membranes and reactivity with DNA. More definitive statements about the toxicological risks of the water soluble chromium complexes requires additional studies with well defined compounds in test systems specially suited to study metal complexes.","A comparison of the mutagenicity of soluble trivalent chromium compounds with that of potassium chromate Abs: The mutagenic potential of water soluble complexes of trivalent chromium with five different amino acids in Salmonella typhimurium strains TA92, TA94, TA98, and TA100 was studied. All complexes were nonmutagenic at concentrations up to 50 mumol/plate in the strains used. In contrast, trivalent chromium chloride was slightly mutagenic in TA98 and a considerable increase in numbers of revertants was observed in TA94. Hexavalent chromium was nonmutagenic in TA98. Strong mutagenic effects were found in TA92, TA94, and TA100. The large difference in mutagenicity between trivalent and hexavalent chromium is discussed with respect to affinity to extracellular phosphate, diffusability through membranes and reactivity with DNA. More definitive statements about the toxicological risks of the water soluble chromium complexes requires additional studies with well defined compounds in test systems specially suited to study metal complexes."
1233976,Becker et al. 1985,Cancer risk of arc welders exposed to fumes containing chromium and nickel,"A retrospective follow-up study among chromium- and nickel-exposed welders, which took into consideration welding procedures, duration of exposure, and smoking habits, yielded an increased cancer risk in a comparison with an internal reference group of turners, milling cutters, and drillers, as well as in a comparison with the general population of the Federal Republic of Germany. Due to the cohort size (1 224 welders, 1 694 turners) and the fact that the observation period is still too short, confirmed statements as to the target cancer sites cannot yet be made. However, it emerges that welding with coated electrodes shows a higher cancer risk as compared to the other welding processes observed. This finding may be explained by the fact that the share of hexavalent chromium compounds in the welding fumes is greater with coated electrodes than with other processes so that a follow-up study observing the health risks of chromium and nickel fumes separately would be warranted. For the confirmation of a more favorable outcome with gas-shielded welding, a larger investigation group or a longer observation period would be required.","Cancer risk of arc welders exposed to fumes containing chromium and nickel Abs: A retrospective follow-up study among chromium- and nickel-exposed welders, which took into consideration welding procedures, duration of exposure, and smoking habits, yielded an increased cancer risk in a comparison with an internal reference group of turners, milling cutters, and drillers, as well as in a comparison with the general population of the Federal Republic of Germany. Due to the cohort size (1 224 welders, 1 694 turners) and the fact that the observation period is still too short, confirmed statements as to the target cancer sites cannot yet be made. However, it emerges that welding with coated electrodes shows a higher cancer risk as compared to the other welding processes observed. This finding may be explained by the fact that the share of hexavalent chromium compounds in the welding fumes is greater with coated electrodes than with other processes so that a follow-up study observing the health risks of chromium and nickel fumes separately would be warranted. For the confirmation of a more favorable outcome with gas-shielded welding, a larger investigation group or a longer observation period would be required."
1233975,Zatka 1985,Speciation of hexavalent chromium in welding fumes interference by air oxidation of chromium,"The determination of various chromium species in welding fume normally involves digestion in a hot alkaline solution. This work confirms that Cr(III) can be oxidized to Cr(VI) during this digestion. However, only dissolved forms of Cr(III), such as the hydroxochromate(III) ion, [Cr(OH)4], are susceptible to oxidation under these conditions. The air oxidation of Cr(III) can be prevented by hydrolytic destabilization of the hydroxochromate(III) complex by the presence of magnesium hydroxide precipitate. The procedure has been used successfully in the determination of insoluble chromium(VI) in welding fumes. Excellent reproducibility is documented for soluble and insoluble chromium(VI) fractions in the analysis of a bulk sample of welding fume.","Speciation of hexavalent chromium in welding fumes interference by air oxidation of chromium Abs: The determination of various chromium species in welding fume normally involves digestion in a hot alkaline solution. This work confirms that Cr(III) can be oxidized to Cr(VI) during this digestion. However, only dissolved forms of Cr(III), such as the hydroxochromate(III) ion, [Cr(OH)4], are susceptible to oxidation under these conditions. The air oxidation of Cr(III) can be prevented by hydrolytic destabilization of the hydroxochromate(III) complex by the presence of magnesium hydroxide precipitate. The procedure has been used successfully in the determination of insoluble chromium(VI) in welding fumes. Excellent reproducibility is documented for soluble and insoluble chromium(VI) fractions in the analysis of a bulk sample of welding fume."
1233970,Kumar et al. 1985,Dysenzymia induced by hexavalent chromium in rat liver,"The alterations in the distribution and activity of certain key enzymes, viz. alkaline phosphatase, acid phosphatase, glucose-6-phosphatase, cholinesterase and lipase, have been determined in the liver of rats (Rattus rattus albino) after experimental poisoning with hexavalent chromium. The histochemical and biochemical observations presented herewith provide visual evidence of chromium-induced inhibition of all these enzymes except lipase, which was found to be stimulated insignificantly. The results have been interpreted in terms of changes in the micro-environment of the cell, formation of apo-enzymes, metal-protein complexes, oxidative phosphorylation and finally with liver function.","Dysenzymia induced by hexavalent chromium in rat liver Abs: The alterations in the distribution and activity of certain key enzymes, viz. alkaline phosphatase, acid phosphatase, glucose-6-phosphatase, cholinesterase and lipase, have been determined in the liver of rats (Rattus rattus albino) after experimental poisoning with hexavalent chromium. The histochemical and biochemical observations presented herewith provide visual evidence of chromium-induced inhibition of all these enzymes except lipase, which was found to be stimulated insignificantly. The results have been interpreted in terms of changes in the micro-environment of the cell, formation of apo-enzymes, metal-protein complexes, oxidative phosphorylation and finally with liver function."
1233966,Levy and  Venitt 1986,Carcinogenicity and mutagenicity of chromium compounds: The association between bronchial metaplasia and neoplasia,"Over the last 40 years, experiments with animals and epidemiology of exposed human populations have established that certain hexavalent chromium-containing compounds are capable of causing cancer whilst trivalent materials are not. More recently, a variety of short-term genotoxicity tests (predictive of carcinogenicity) have clearly demonstrated that Cr[VI] is genotoxic per se, and that all Cr[VI]-containing materials which have been tested are genotoxic. What experiments have failed to demonstrate clearly, however, is which of the myriad of industrially available hexavalent materials are carcinogenic and which are not. In this long-term study we have looked at the incidence of squamous metaplasia in the bronchial epithelium of rats exposed to a range of chromium-containing materials by intrabronchial implantation. Squamous metaplasia is generally considered to be a transformed state from which squamous carcinoma may arise. We have shown that its incidence is increased in all groups exposed to Cr[VI]-materials, and in rats exposed to the reference carcinogen 20-methylcholanthrene. Squamous metaplasia was not increased in rats exposed to Cr[III] materials. Of rats exposed to Cr[VI], only those receiving materials of sparing aqueous solubility developed bronchial squamous carcinoma at statistically significant levels. These results strongly support the hypothesis that although Cr[VI] per se is biologically active, producing genotoxic effects and pathological changes which may predispose to the development of cancer, only Cr[VI] materials of sparing aqueous solubility seem to be capable of evoking a carcinogenic response.","Carcinogenicity and mutagenicity of chromium compounds: The association between bronchial metaplasia and neoplasia Abs: Over the last 40 years, experiments with animals and epidemiology of exposed human populations have established that certain hexavalent chromium-containing compounds are capable of causing cancer whilst trivalent materials are not. More recently, a variety of short-term genotoxicity tests (predictive of carcinogenicity) have clearly demonstrated that Cr[VI] is genotoxic per se, and that all Cr[VI]-containing materials which have been tested are genotoxic. What experiments have failed to demonstrate clearly, however, is which of the myriad of industrially available hexavalent materials are carcinogenic and which are not. In this long-term study we have looked at the incidence of squamous metaplasia in the bronchial epithelium of rats exposed to a range of chromium-containing materials by intrabronchial implantation. Squamous metaplasia is generally considered to be a transformed state from which squamous carcinoma may arise. We have shown that its incidence is increased in all groups exposed to Cr[VI]-materials, and in rats exposed to the reference carcinogen 20-methylcholanthrene. Squamous metaplasia was not increased in rats exposed to Cr[III] materials. Of rats exposed to Cr[VI], only those receiving materials of sparing aqueous solubility developed bronchial squamous carcinoma at statistically significant levels. These results strongly support the hypothesis that although Cr[VI] per se is biologically active, producing genotoxic effects and pathological changes which may predispose to the development of cancer, only Cr[VI] materials of sparing aqueous solubility seem to be capable of evoking a carcinogenic response."
1233964,Nagaya 1986,No increase in sister-chromatid exchange frequency in lymphocytes of chromium platers,"To detect mutagenic effects of hexavalent chromium (Cr) in vivo, sister-chromatid exchange (SCE) frequency was analyzed in lymphocytes of 24 Cr platers occupationally exposed to hexavalent Cr and 24 matched controls. There were no significant differences in SCE frequency between the two groups. Smokers, both Cr platers and controls, had a significantly higher SCE frequency than non-smokers.","No increase in sister-chromatid exchange frequency in lymphocytes of chromium platers Abs: To detect mutagenic effects of hexavalent chromium (Cr) in vivo, sister-chromatid exchange (SCE) frequency was analyzed in lymphocytes of 24 Cr platers occupationally exposed to hexavalent Cr and 24 matched controls. There were no significant differences in SCE frequency between the two groups. Smokers, both Cr platers and controls, had a significantly higher SCE frequency than non-smokers."
1233962,Llagostera et al. 1986,Induction of SOS genes of Escherichia coli by chromium compounds,"The induction of several SOS genes of Escherichia coli such as recA, umuC, and sfiA by hexavalent (K2Cr2O7, K2CrO4, and CrO3) and trivalent (CrCl3, Cr(NO3)3, and (CH3COO)3Cr) compounds of chromium was studied. Induction was measured as beta-galactosidase activity, using lacZ gene fusions under the control region of different SOS genes. The hexavalent chromium forms induced the genes responsible for massive synthesis of RecA protein, error-prone repair, and inhibition of cell division. On the other hand, the trivalent chromium compounds were unable to induce any of the SOS genes tested. Individual assay of hexavalent chromium compounds showed that K2Cr2O7 was a stronger inducing agent of those three SOS genes tested than K2CrO4, which, in turn, was stronger than CrO3. All this data led to the conclusion that hexavalent chromium compounds, but not trivalent, are proficient agents of induction of the SOS system and can produce indirect mutagenesis in Escherichia coli.","Induction of SOS genes of Escherichia coli by chromium compounds Abs: The induction of several SOS genes of Escherichia coli such as recA, umuC, and sfiA by hexavalent (K2Cr2O7, K2CrO4, and CrO3) and trivalent (CrCl3, Cr(NO3)3, and (CH3COO)3Cr) compounds of chromium was studied. Induction was measured as beta-galactosidase activity, using lacZ gene fusions under the control region of different SOS genes. The hexavalent chromium forms induced the genes responsible for massive synthesis of RecA protein, error-prone repair, and inhibition of cell division. On the other hand, the trivalent chromium compounds were unable to induce any of the SOS genes tested. Individual assay of hexavalent chromium compounds showed that K2Cr2O7 was a stronger inducing agent of those three SOS genes tested than K2CrO4, which, in turn, was stronger than CrO3. All this data led to the conclusion that hexavalent chromium compounds, but not trivalent, are proficient agents of induction of the SOS system and can produce indirect mutagenesis in Escherichia coli."
1233961,Rafnsson and  Jóhannesdóttir 1986,Mortality among masons in Iceland,"An investigation was carried out to determine the cause of death among 450 masons in Iceland who had been exposed to hexavalent chromium, a trace element in cement. The cohort was defined as all men born between 1905 and 1945 who had, according to the Register of Masons and Stone-cutters, finished vocational training as masons. For deaths occurring between 1951 and 1982 information was obtained from the Statistical Bureau of Iceland. Expected death rates were calculated, based on the national rates for men in the corresponding age groups. The total number of deaths from all causes was less than expected for the whole study period (81 v 85.86) but, with a 20 year latent period, 58 deaths were found against 50.57 expected; with a 30 year latent period, 38 deaths were found against 27.82 expected, which may, to a large extent, be accounted for by an excess of deaths from lung cancer. Nine deaths from lung cancer were found in the cohort, eight with 20 and 30 year latent periods compared with expected rates of 2.87, 2.19, and 1.28 respectively. The results seem to indicate that the increased number of deaths from lung cancer among the masons has a causal relation to occupational exposure.","Mortality among masons in Iceland Abs: An investigation was carried out to determine the cause of death among 450 masons in Iceland who had been exposed to hexavalent chromium, a trace element in cement. The cohort was defined as all men born between 1905 and 1945 who had, according to the Register of Masons and Stone-cutters, finished vocational training as masons. For deaths occurring between 1951 and 1982 information was obtained from the Statistical Bureau of Iceland. Expected death rates were calculated, based on the national rates for men in the corresponding age groups. The total number of deaths from all causes was less than expected for the whole study period (81 v 85.86) but, with a 20 year latent period, 58 deaths were found against 50.57 expected; with a 30 year latent period, 38 deaths were found against 27.82 expected, which may, to a large extent, be accounted for by an excess of deaths from lung cancer. Nine deaths from lung cancer were found in the cohort, eight with 20 and 30 year latent periods compared with expected rates of 2.87, 2.19, and 1.28 respectively. The results seem to indicate that the increased number of deaths from lung cancer among the masons has a causal relation to occupational exposure."
1233960,De Flora et al. 1986,"Detoxifying activities in alveolar macrophages of rats treated with acetylcysteine, diethyl maleate and/or aroclor","Single or sequential treatment of rats with the thiol N-acetyl-L-cysteine (NAC), the glutathione depletor diethyl maleate (DEM) and the enzyme inducer Aroclor 1254 (AR) produced several significant variations on metabolic activities of pulmonary alveolar macrophages (PAM). Specifically, all three compounds elicited an increase in some oxidoreductase activities, including the two dehydrogenases involved in the hexose monophosphate shunt (G6PD and 6PGD) and NADH- or NADPH-dependent diaphorases. Diaphorase activities were especially increased by sequential treatments with AR and DEM or with DEM and NAC. Both NAC and AR also stimulated other detoxifying mechanisms, such as those related to GSH S-transferase activity and to the NADPH-dependent reduction of hexavalent chromium. Therefore, all the monitored parameters were significantly enhanced not only by the enzyme inducer, but also by the thiol, demonstrating its protective role in the biotransformation of mutagenic/carcinogenic compounds.","Detoxifying activities in alveolar macrophages of rats treated with acetylcysteine, diethyl maleate and/or aroclor Abs: Single or sequential treatment of rats with the thiol N-acetyl-L-cysteine (NAC), the glutathione depletor diethyl maleate (DEM) and the enzyme inducer Aroclor 1254 (AR) produced several significant variations on metabolic activities of pulmonary alveolar macrophages (PAM). Specifically, all three compounds elicited an increase in some oxidoreductase activities, including the two dehydrogenases involved in the hexose monophosphate shunt (G6PD and 6PGD) and NADH- or NADPH-dependent diaphorases. Diaphorase activities were especially increased by sequential treatments with AR and DEM or with DEM and NAC. Both NAC and AR also stimulated other detoxifying mechanisms, such as those related to GSH S-transferase activity and to the NADPH-dependent reduction of hexavalent chromium. Therefore, all the monitored parameters were significantly enhanced not only by the enzyme inducer, but also by the thiol, demonstrating its protective role in the biotransformation of mutagenic/carcinogenic compounds."
1233958,Berg et al. 1987,Bronchocarcinogenic properties of welding and thermal spraying fumes containing chromium in the rat,"The possible bronchocarcinogenic effects of fumes released during the shielded metal arc welding of stainless steel and the thermal spraying of chromium oxide (Cr2O3) have been studied on the rat. The fume particles were shown to contain tri- and hexavalent chromium in soluble and low soluble forms; they were collected and implanted as pellets in the bronchi of groups of 100 rats by the method of Laskin et al. A negative control group of 100 rats was included, as well as positive controls receiving pellets containing benz(a)pyrene. The experiment was continued for 34 months; no differences of biological significance were noted between the growth rates, survival times, and terminal organ weights of the test and negative control groups. At autopsy, the macroscopic and microscopic appearance of the organs in the three groups, including the local reaction to the implanted pellet, were similar. No precancerous changes were observed at the implantation sites; one rat, who received a pellet containing welding fumes, showed squamous cell carcinoma remote from the implantation site and not associated with the bronchus. It had the appearance of a metastasis. All three benz(a)pyrene control rats developed cancer at the implantation site. The occupational health implications of these findings are discussed.","Bronchocarcinogenic properties of welding and thermal spraying fumes containing chromium in the rat Abs: The possible bronchocarcinogenic effects of fumes released during the shielded metal arc welding of stainless steel and the thermal spraying of chromium oxide (Cr2O3) have been studied on the rat. The fume particles were shown to contain tri- and hexavalent chromium in soluble and low soluble forms; they were collected and implanted as pellets in the bronchi of groups of 100 rats by the method of Laskin et al. A negative control group of 100 rats was included, as well as positive controls receiving pellets containing benz(a)pyrene. The experiment was continued for 34 months; no differences of biological significance were noted between the growth rates, survival times, and terminal organ weights of the test and negative control groups. At autopsy, the macroscopic and microscopic appearance of the organs in the three groups, including the local reaction to the implanted pellet, were similar. No precancerous changes were observed at the implantation sites; one rat, who received a pellet containing welding fumes, showed squamous cell carcinoma remote from the implantation site and not associated with the bronchus. It had the appearance of a metastasis. All three benz(a)pyrene control rats developed cancer at the implantation site. The occupational health implications of these findings are discussed."
1233957,Pillard et al. 1987,Hexavalent chromium effects on carbon assimilation in Selenastrum capricornutum,,Hexavalent chromium effects on carbon assimilation in Selenastrum capricornutum Abs: 
1233956,Sjögren et al. 1987,Mortality in two cohorts of welders exposed to high- and low-levels of hexavalent chromium,"Hexavalent chromium particles are generated in the welding of stainless steel. These particles have manifested a mutagenic action in bacterial test systems and produced chromosome aberrations in cultured Chinese hamster cells. A cohort consisting of 234 welders working on stainless steel and exposed to high levels of chromium was selected. According to an earlier survey the hexavalent chromium exposure of such welders was often above 20 micrograms/m3. Another cohort consisting of 208 railway track welders exposed to low levels of chromium was also selected. The participants of both cohorts had welded for at least five years some time between 1950 and 1965 and were followed for mortality until December 1984. Among the welders exposed to high chromium levels five deaths occurred due to pulmonary tumors. This number is significantly greater than the one death that occurred among the welders exposed to low levels of chromium, but not significantly greater than the corresponding mortality of the general population. Thus exposure to stainless steel welding fumes might be associated with an increased incidence of pulmonary tumors.","Mortality in two cohorts of welders exposed to high- and low-levels of hexavalent chromium Abs: Hexavalent chromium particles are generated in the welding of stainless steel. These particles have manifested a mutagenic action in bacterial test systems and produced chromosome aberrations in cultured Chinese hamster cells. A cohort consisting of 234 welders working on stainless steel and exposed to high levels of chromium was selected. According to an earlier survey the hexavalent chromium exposure of such welders was often above 20 micrograms/m3. Another cohort consisting of 208 railway track welders exposed to low levels of chromium was also selected. The participants of both cohorts had welded for at least five years some time between 1950 and 1965 and were followed for mortality until December 1984. Among the welders exposed to high chromium levels five deaths occurred due to pulmonary tumors. This number is significantly greater than the one death that occurred among the welders exposed to low levels of chromium, but not significantly greater than the corresponding mortality of the general population. Thus exposure to stainless steel welding fumes might be associated with an increased incidence of pulmonary tumors."
1233954,Eik-Nes et al. 1987,Corticosteroids and lung surfactant levels in adult male rats,"Following lung instillation in adult male rats of 3.4 mumol hexavalent chromium (K2Cr2O7) dissolved in 0.5 ml of 0.9% NaCl, increased levels of lung surfactant could be detected after 48 h. The blood serum concentration of corticosterone was elevated in these animals. Blood serum thyroxine and triiodothyronine showed an initial increase after lung instillation of hexavalent chromium followed by a decline. Metabolism of testosterone by the alveolar macrophages to 17 beta-hydroxy-5 alpha-androstane-3-one and 5 alpha-androstane-3 alpha, 17 beta-diol was reduced 6 and 12 h after the K2Cr2O7 instillation, which was also associated with damage of lung cell function and decreased uptake by the alveolar macrophages of Candida albicans particles. As early as 12 h after s.c. administration of 400 micrograms dexamethasone/100 g body wt, increased levels of lung surfactant could be measured. At this time the lungs showed no signs of cellular damage, and metabolism of testosterone as well as uptake of Candida albicans particles by the alveolar macrophages were normal. Lower s.c. doses of dexamethasone did not result in raising the levels of lung surfactant in 12 h. Within 12 h after s.c. administration of large doses of testosterone, dihydrotestosterone or dehydroepiandrosterone no measurable effects on the levels of lung surfactant could be measured. Since animals treated with dexamethasone (200 micrograms/100 g body wt) or long-acting synthetic ACTH (100 micrograms i.m. Synacthen Depot/100 g body wt) for 5 days after lung instillation of K2Cr2O7 had extremely high levels of lung surfactant, it is concluded that the corticosteroids in adult rats may help to create augmented surfactant levels following lung intoxication. This could proceed via stimulation of surfactant production and reduction of surfactant removal. Different aspects of lung surfactant metabolism are discussed.","Corticosteroids and lung surfactant levels in adult male rats Abs: Following lung instillation in adult male rats of 3.4 mumol hexavalent chromium (K2Cr2O7) dissolved in 0.5 ml of 0.9% NaCl, increased levels of lung surfactant could be detected after 48 h. The blood serum concentration of corticosterone was elevated in these animals. Blood serum thyroxine and triiodothyronine showed an initial increase after lung instillation of hexavalent chromium followed by a decline. Metabolism of testosterone by the alveolar macrophages to 17 beta-hydroxy-5 alpha-androstane-3-one and 5 alpha-androstane-3 alpha, 17 beta-diol was reduced 6 and 12 h after the K2Cr2O7 instillation, which was also associated with damage of lung cell function and decreased uptake by the alveolar macrophages of Candida albicans particles. As early as 12 h after s.c. administration of 400 micrograms dexamethasone/100 g body wt, increased levels of lung surfactant could be measured. At this time the lungs showed no signs of cellular damage, and metabolism of testosterone as well as uptake of Candida albicans particles by the alveolar macrophages were normal. Lower s.c. doses of dexamethasone did not result in raising the levels of lung surfactant in 12 h. Within 12 h after s.c. administration of large doses of testosterone, dihydrotestosterone or dehydroepiandrosterone no measurable effects on the levels of lung surfactant could be measured. Since animals treated with dexamethasone (200 micrograms/100 g body wt) or long-acting synthetic ACTH (100 micrograms i.m. Synacthen Depot/100 g body wt) for 5 days after lung instillation of K2Cr2O7 had extremely high levels of lung surfactant, it is concluded that the corticosteroids in adult rats may help to create augmented surfactant levels following lung intoxication. This could proceed via stimulation of surfactant production and reduction of surfactant removal. Different aspects of lung surfactant metabolism are discussed."
1233952,Gray 1987,Hexavalent chromium in welding fume and the role of ozone,,Hexavalent chromium in welding fume and the role of ozone Abs: 
1233950,De Flora et al. 1988,Influence of DT diaphorase on the mutagenicity of organic and inorganic compounds,"The metabolic activation or detoxification of mutagens and carcinogens of several chemical classes was investigated in the presence of various rat liver and lung subcellular fractions and of dicoumarol, a specific inhibitor of DT diaphorase activity. His- Salmonella typhimurium strains were used as targets of mutagenicity. Dicoumarol partially prevented the metabolic activation of some promutagens, such as the heterocyclic amines 2-amino-3,4-dimethylimidazo[4,5-f]quinoline and 3-amino-1-methyl-5H-pyrido[4,3-b]indole, and a cigarette smoke condensate. Moreover, detailed experiments, also using purified enzyme, confirmed the participation of DT diaphorase in the metabolic reduction of 4-nitroquinoline N-oxide 4NQO and of hexavalent chromium [Cr(VI)] compounds. The results obtained provide evidence for broad involvement of DT diaphorase in the metabolism of both organic and inorganic mutagens and carcinogens. Moreover, they suggest a dual role of this enzyme, providing not only a cellular detoxifying system but also, with a few substrates, an activating mechanism.","Influence of DT diaphorase on the mutagenicity of organic and inorganic compounds Abs: The metabolic activation or detoxification of mutagens and carcinogens of several chemical classes was investigated in the presence of various rat liver and lung subcellular fractions and of dicoumarol, a specific inhibitor of DT diaphorase activity. His- Salmonella typhimurium strains were used as targets of mutagenicity. Dicoumarol partially prevented the metabolic activation of some promutagens, such as the heterocyclic amines 2-amino-3,4-dimethylimidazo[4,5-f]quinoline and 3-amino-1-methyl-5H-pyrido[4,3-b]indole, and a cigarette smoke condensate. Moreover, detailed experiments, also using purified enzyme, confirmed the participation of DT diaphorase in the metabolic reduction of 4-nitroquinoline N-oxide 4NQO and of hexavalent chromium [Cr(VI)] compounds. The results obtained provide evidence for broad involvement of DT diaphorase in the metabolism of both organic and inorganic mutagens and carcinogens. Moreover, they suggest a dual role of this enzyme, providing not only a cellular detoxifying system but also, with a few substrates, an activating mechanism."
1233949,Tola et al. 1988,"Incidence of cancer among welders, platers, machinists, and pipe fitters in shipyards and machine shops","The incidence of cancer in 12,693 shipyard and machine shop male workers (1689 welders, 4308 platers, 6003 machinists, 693 pipe fitters) employed for at least one year between 1945 and 1960 was investigated in a retrospective cohort study. The welders had welded only mild steel and had not been exposed to hexavalent chromium containing fume. The follow up was 99.7% complete and the total number of person-years was 304,682. The incidence of cancer in 1953-81 was ascertained through the Finnish Cancer Registry. The observed numbers of cases of cancer were compared with the expected numbers based on regional urban rates. The smoking habits of the cohort were surveyed with a postal questionnaire sent to a sample of 961 workers. The smoking habits of the cohorts were similar and smoking was not more common than among the general population. The total number of cases of cancer was 611 (exp 629) among the shipyard workers and 376 (exp 388) among the machine shop workers. The incidence of lung cancer was increased among the shipyard workers (obs 227, exp 192). This excess was observed in all the worker groups and was most evident for the pipe fitters and platers. Among the machine shop workers, the incidence of lung cancer was lower than expected with the exception of the welders who had a slightly raised risk of lung cancer (obs 14, exp 10). The incidence of laryngeal cancer was slightly raised among the shipyard workers (obs 24, exp 20) but not in the machine shop workers. No excess risk was observed among the welders. The incidence of cancer of the prostate was increased among the machine shop workers (obs 39, exp 31) but not in the shipyard workers. The excess was statistically significant for the welders. No pronounced excess could be found for other types of cancer. Analysis by the duration or exposure showed that the excess of lung cancer in the shipyard workers was most evident during the last period of observation (1972-81). No other trends were obvious and the slight excess of lung cancer observed among the welders did not increase with increasing follow up time. No excess risk for mesothelioma was found. The small excess of lung cancer in welders could be due to chance. The fact that only a small and statistically insignificant excess of lung cancer could be found among this group of heavily exposed welders suggest that if the risk of lung cancer was associated with welding this risk must nowadays be low and probably too low to be unequivocally detected in most epidemiological studies.","Incidence of cancer among welders, platers, machinists, and pipe fitters in shipyards and machine shops Abs: The incidence of cancer in 12,693 shipyard and machine shop male workers (1689 welders, 4308 platers, 6003 machinists, 693 pipe fitters) employed for at least one year between 1945 and 1960 was investigated in a retrospective cohort study. The welders had welded only mild steel and had not been exposed to hexavalent chromium containing fume. The follow up was 99.7% complete and the total number of person-years was 304,682. The incidence of cancer in 1953-81 was ascertained through the Finnish Cancer Registry. The observed numbers of cases of cancer were compared with the expected numbers based on regional urban rates. The smoking habits of the cohort were surveyed with a postal questionnaire sent to a sample of 961 workers. The smoking habits of the cohorts were similar and smoking was not more common than among the general population. The total number of cases of cancer was 611 (exp 629) among the shipyard workers and 376 (exp 388) among the machine shop workers. The incidence of lung cancer was increased among the shipyard workers (obs 227, exp 192). This excess was observed in all the worker groups and was most evident for the pipe fitters and platers. Among the machine shop workers, the incidence of lung cancer was lower than expected with the exception of the welders who had a slightly raised risk of lung cancer (obs 14, exp 10). The incidence of laryngeal cancer was slightly raised among the shipyard workers (obs 24, exp 20) but not in the machine shop workers. No excess risk was observed among the welders. The incidence of cancer of the prostate was increased among the machine shop workers (obs 39, exp 31) but not in the shipyard workers. The excess was statistically significant for the welders. No pronounced excess could be found for other types of cancer. Analysis by the duration or exposure showed that the excess of lung cancer in the shipyard workers was most evident during the last period of observation (1972-81). No other trends were obvious and the slight excess of lung cancer observed among the welders did not increase with increasing follow up time. No excess risk for mesothelioma was found. The small excess of lung cancer in welders could be due to chance. The fact that only a small and statistically insignificant excess of lung cancer could be found among this group of heavily exposed welders suggest that if the risk of lung cancer was associated with welding this risk must nowadays be low and probably too low to be unequivocally detected in most epidemiological studies."
1233947,Nath and  Kumar 1988,"Hexavalent chromium: toxicity and its impact on certain aspects of carbohydrate metabolism of the freshwater teleost, Colisa fasciatus","The effect of hexavalent chromium on the static bioassay was examined. The LC0, LC50 and LC100 values at 24, 48, 72 and 96 h were determined. At 96 h, the LC50 value was found to be 60 mg l-1 or 6.000 x 10(-4) mol l-1. The impact of a sublethal concentration of 48 ppm on the liver glycogen and blood glucose levels was investigated during 3-96 h. Liver glycogen exhibited significant depletion with all exposure periods except 3 h. Blood glucose level increased significantly from 6 h onwards, attaining its peak value at 72 h.","Hexavalent chromium: toxicity and its impact on certain aspects of carbohydrate metabolism of the freshwater teleost, Colisa fasciatus Abs: The effect of hexavalent chromium on the static bioassay was examined. The LC0, LC50 and LC100 values at 24, 48, 72 and 96 h were determined. At 96 h, the LC50 value was found to be 60 mg l-1 or 6.000 x 10(-4) mol l-1. The impact of a sublethal concentration of 48 ppm on the liver glycogen and blood glucose levels was investigated during 3-96 h. Liver glycogen exhibited significant depletion with all exposure periods except 3 h. Blood glucose level increased significantly from 6 h onwards, attaining its peak value at 72 h."
1233944,McAughey et al. 1988,Biological monitoring of occupational exposure in the chromate pigment production industry,"A survey of occupational exposure to hexavalent chromium in chromate pigment production was undertaken in factories producing lead chromate (PbCrO4) and strontium chromate (SrCrO4). Sampling pre and post-shift in a factory where SrCrO4 production had just started showed the optimum strategy for biological monitoring is the measurement of urinary chromium, in urine samples taken at the end of Friday shift and pre-shift the following Monday. However, short-term uptake may be assessed under these circumstances by the increase in urinary chromium over a shift. Body burden, representing long-term chromate exposure is best assessed by measuring chromium in whole blood or pre-shift urinary chromium at the beginning of the working week. Exceptionally high levels of chromium in blood (387-4160 nmol l-1) and urine (41-1250 nmol nmol-1 creatinine) as well as skin and nasal lesions, were discovered amongst the workforce at the strontium chromate plant. These contrasted with occupationally unexposed levels of less than 20 nmol l-1 and less than 1 nmol nmol-1 creatinine, respectively, and led to the continuation of the biological monitoring programme. At the same time, improved working practices and respiratory protection equipment were introduced. A steady elimination of chromium from whole blood with a half-life of approximately 24 days was found. This elimination rate was confirmed over a 14 day period when the workforce were completely removed from exposure. The study confirms the usefulness of biological monitoring in assessing the uptake of hexavalent chromium and control of exposure.","Biological monitoring of occupational exposure in the chromate pigment production industry Abs: A survey of occupational exposure to hexavalent chromium in chromate pigment production was undertaken in factories producing lead chromate (PbCrO4) and strontium chromate (SrCrO4). Sampling pre and post-shift in a factory where SrCrO4 production had just started showed the optimum strategy for biological monitoring is the measurement of urinary chromium, in urine samples taken at the end of Friday shift and pre-shift the following Monday. However, short-term uptake may be assessed under these circumstances by the increase in urinary chromium over a shift. Body burden, representing long-term chromate exposure is best assessed by measuring chromium in whole blood or pre-shift urinary chromium at the beginning of the working week. Exceptionally high levels of chromium in blood (387-4160 nmol l-1) and urine (41-1250 nmol nmol-1 creatinine) as well as skin and nasal lesions, were discovered amongst the workforce at the strontium chromate plant. These contrasted with occupationally unexposed levels of less than 20 nmol l-1 and less than 1 nmol nmol-1 creatinine, respectively, and led to the continuation of the biological monitoring programme. At the same time, improved working practices and respiratory protection equipment were introduced. A steady elimination of chromium from whole blood with a half-life of approximately 24 days was found. This elimination rate was confirmed over a 14 day period when the workforce were completely removed from exposure. The study confirms the usefulness of biological monitoring in assessing the uptake of hexavalent chromium and control of exposure."
1233943,Wiegand et al. 1988,Recent advances in biological monitoring of hexavalent chromium compounds,"Intratracheal instillation of 51CrCl3 in anaesthetized rabbits resulted in partial absorption. In blood, the absorbed material was entirely confined to the plasma compartment. By contrast, after similar application of Na251CrO4 the bulk of blood radioactivity was present in red blood cells (RBC). It is suggested that Cr (VI) may enter the body not reduced via the lung and may be deposited in RBC for the cell's lifetime (approximately 110 d). Since inhalation of Cr (VI)-containing aerosols or particles is the main occupational exposure route for man, it is concluded that the chromium content of RBC could be used as a selective biological indicator for exposures to (carcinogenic) hexavalent chromium. The new theoretical concept was confirmed in a pilot study with workers of a dye pigment plant. Elevated chromium content of whole blood evoked by exposure to chromate particles correlated strongly with increased chromium values in RBC (correlation coefficient: 0.86).","Recent advances in biological monitoring of hexavalent chromium compounds Abs: Intratracheal instillation of 51CrCl3 in anaesthetized rabbits resulted in partial absorption. In blood, the absorbed material was entirely confined to the plasma compartment. By contrast, after similar application of Na251CrO4 the bulk of blood radioactivity was present in red blood cells (RBC). It is suggested that Cr (VI) may enter the body not reduced via the lung and may be deposited in RBC for the cell's lifetime (approximately 110 d). Since inhalation of Cr (VI)-containing aerosols or particles is the main occupational exposure route for man, it is concluded that the chromium content of RBC could be used as a selective biological indicator for exposures to (carcinogenic) hexavalent chromium. The new theoretical concept was confirmed in a pilot study with workers of a dye pigment plant. Elevated chromium content of whole blood evoked by exposure to chromate particles correlated strongly with increased chromium values in RBC (correlation coefficient: 0.86)."
1233941,Briggs and  Briggs 1988,Characterization of chromium effects on a rat liver epithelial cell line and their relevance to in vitro transformation,"Chronic exposure to low concentrations or brief exposures to high concentrations of hexavalent chromium (K2CrO4) transformed a rat liver epithelial cell line as assessed by anchorage-independent growth. A clone of the transformed cells produced tumors in syngeneic animals, all of which were determined to be high grade carcinomas. The effects of various doses of chromium on cytotoxicity and cell cycle were established and related to ultimate numbers of transformants in the population. Prior to the onset of cytotoxicity, linear rates of uptake were observed at different external concentrations of chromium and the total intracellular level increased with increasing concentration. This may be due to competition for transport. A plateau in level of chromium accumulation after prolonged exposure to a low concentration (10 microM) of chromium observed with the eventual return to normal growth provided evidence for the induction of a protective mechanism. In addition, cells surviving prolonged treatment with low concentrations of chromium became resistant to the cytotoxic effects of high concentrations of the metal, further suggesting that the cells become adapted to the presence of chromium. An increase in the amount of protein associated with extracted nucleic acids was detected at the optimal transforming dose and this did not correlate with cytotoxic effects. The effectiveness of chromium in transforming the adult rat liver epithelial cell line may depend on the intracellular level of accumulation, the rate of chromium uptake, and the ability of the cell to activate a protective mechanism. The initiation of stable nucleic acid-protein complexes observed under the optimal conditions for transformation may be associated with an inability of the cell to activate a protective mechanism rapidly enough to prevent effects on the nucleus at a high concentration (1 mM) of chromium.","Characterization of chromium effects on a rat liver epithelial cell line and their relevance to in vitro transformation Abs: Chronic exposure to low concentrations or brief exposures to high concentrations of hexavalent chromium (K2CrO4) transformed a rat liver epithelial cell line as assessed by anchorage-independent growth. A clone of the transformed cells produced tumors in syngeneic animals, all of which were determined to be high grade carcinomas. The effects of various doses of chromium on cytotoxicity and cell cycle were established and related to ultimate numbers of transformants in the population. Prior to the onset of cytotoxicity, linear rates of uptake were observed at different external concentrations of chromium and the total intracellular level increased with increasing concentration. This may be due to competition for transport. A plateau in level of chromium accumulation after prolonged exposure to a low concentration (10 microM) of chromium observed with the eventual return to normal growth provided evidence for the induction of a protective mechanism. In addition, cells surviving prolonged treatment with low concentrations of chromium became resistant to the cytotoxic effects of high concentrations of the metal, further suggesting that the cells become adapted to the presence of chromium. An increase in the amount of protein associated with extracted nucleic acids was detected at the optimal transforming dose and this did not correlate with cytotoxic effects. The effectiveness of chromium in transforming the adult rat liver epithelial cell line may depend on the intracellular level of accumulation, the rate of chromium uptake, and the ability of the cell to activate a protective mechanism. The initiation of stable nucleic acid-protein complexes observed under the optimal conditions for transformation may be associated with an inability of the cell to activate a protective mechanism rapidly enough to prevent effects on the nucleus at a high concentration (1 mM) of chromium."
1233936,Nagaya et al. 1989,Sister chromatid exchange analysis in lymphocytes of workers exposed to hexavalent chromium,"To investigate the usefulness of sister chromatid exchange (SCE) analysis in lymphocytes as an indicator for mutagenic effects after in vivo exposure to hexavalent chromium (Cr), SCE frequency was analysed in lymphocytes of 44 Cr platers occupationally exposed to hexavalent Cr and 47 controls. Although urinary Cr analysis confirmed that the Cr platers were exposed to Cr, no effects of the exposure on SCE frequency were found. Smokers, both Cr platers and controls, had a significantly higher SCE frequency than non-smokers. These results suggest that SCE analysis in human lymphocytes is not a good indicator of possible mutagenic effects of exposure to hexavalent Cr.","Sister chromatid exchange analysis in lymphocytes of workers exposed to hexavalent chromium Abs: To investigate the usefulness of sister chromatid exchange (SCE) analysis in lymphocytes as an indicator for mutagenic effects after in vivo exposure to hexavalent chromium (Cr), SCE frequency was analysed in lymphocytes of 44 Cr platers occupationally exposed to hexavalent Cr and 47 controls. Although urinary Cr analysis confirmed that the Cr platers were exposed to Cr, no effects of the exposure on SCE frequency were found. Smokers, both Cr platers and controls, had a significantly higher SCE frequency than non-smokers. These results suggest that SCE analysis in human lymphocytes is not a good indicator of possible mutagenic effects of exposure to hexavalent Cr."
1233935,Ueno et al. 1989,Cellular injury and lipid peroxidation induced by hexavalent chromium in isolated rat hepatocytes,"In order to elucidate the relationship between cellular injury and lipid peroxidation induced by hexavalent chromium (CrVI), isolated rat hepatocytes treated with any one of scavengers of active oxygen species, antioxidants or antichromium agent were incubated with K2Cr2O7 as CrVI (1 mM Cr). After the incubation, the development of lipid peroxidation was determined as thiobarbituric acid (TBA)-reacting materials in total lipid extracts from the incubated hepatocytes. Cellular injury was observed as a leakage of lactate dehydrogenase (LDH) from hepatocytes into incubation medium. The contents of reduced glutathione (GSH) in hepatocytes were also assessed. Results obtained were as follows: (1) CrVI facilitated lipid peroxidation in isolated hepatocytes after 20 min of incubation. On the other hand, the cellular injury induced by CrVI was barely observed even after 60 min of incubation. (2) The CrVI-induced lipid peroxidation was inhibited by catalase and mannitol as scavengers of active oxygen species, or N,N'-diphenyl-p-phenylenediamine and alpha-tocopherol as antioxidants. However the cytotoxicity of CrVI could not be prevented by these chemicals. (3) CrVI depleted the contents of intracellular GSH and diminished the activities of glutathione reductase (GR) and glutathione-S-transferase (GST) except glutathione peroxidase. (4) The scavengers of active oxygen species and the antioxidants could not prevent the depletion of intracellular GSH induced by CrVI. (6) Ascorbic acid, antichromium agent, prevented all of the lipid peroxidation, the cellular injury and intracellular GSH depletion induced by CrVI.(ABSTRACT TRUNCATED AT 250 WORDS)","Cellular injury and lipid peroxidation induced by hexavalent chromium in isolated rat hepatocytes Abs: In order to elucidate the relationship between cellular injury and lipid peroxidation induced by hexavalent chromium (CrVI), isolated rat hepatocytes treated with any one of scavengers of active oxygen species, antioxidants or antichromium agent were incubated with K2Cr2O7 as CrVI (1 mM Cr). After the incubation, the development of lipid peroxidation was determined as thiobarbituric acid (TBA)-reacting materials in total lipid extracts from the incubated hepatocytes. Cellular injury was observed as a leakage of lactate dehydrogenase (LDH) from hepatocytes into incubation medium. The contents of reduced glutathione (GSH) in hepatocytes were also assessed. Results obtained were as follows: (1) CrVI facilitated lipid peroxidation in isolated hepatocytes after 20 min of incubation. On the other hand, the cellular injury induced by CrVI was barely observed even after 60 min of incubation. (2) The CrVI-induced lipid peroxidation was inhibited by catalase and mannitol as scavengers of active oxygen species, or N,N'-diphenyl-p-phenylenediamine and alpha-tocopherol as antioxidants. However the cytotoxicity of CrVI could not be prevented by these chemicals. (3) CrVI depleted the contents of intracellular GSH and diminished the activities of glutathione reductase (GR) and glutathione-S-transferase (GST) except glutathione peroxidase. (4) The scavengers of active oxygen species and the antioxidants could not prevent the depletion of intracellular GSH induced by CrVI. (6) Ascorbic acid, antichromium agent, prevented all of the lipid peroxidation, the cellular injury and intracellular GSH depletion induced by CrVI.(ABSTRACT TRUNCATED AT 250 WORDS)"
1233933,Ginter et al. 1989,Vitamin C lowers mutagenic and toxic effect of hexavalent chromium in guinea pigs,"The mutagenic effect of intraperitoneally injected K2Cr2O7 was significantly higher in vitamin C-deficient guinea pigs than in animals fed diet with high vitamin C content. Mutagenic and toxic effects of hexavalent chromium were more expressed in vitamin C-deficient guinea pigs administered K2Cr2O7 in drinking water: the number of micronuclei in polychromatic erythrocytes of bone marrow was increased, and the activity of O-demethylase and the levels of cytochromes P-450 and b5 in liver microsomes were decreased. In guinea pigs fed high vitamin C diet the same doses of bichromate in drinking water evoked no mutagenic changes in the bone marrow and no changes in microsomal enzymes in the liver. These results indicate that high intake of ascorbic acid in the diet reduces mutagenic effects of K2Cr2O7 and its toxic influence on drug metabolizing enzymes in hepatocytes. The protective effect ascorbic acid consists most probably in the enhanced extracellular and intracellular reduction of hexavalent chromium to the less toxic and less mutagenic trivalent chromium.","Vitamin C lowers mutagenic and toxic effect of hexavalent chromium in guinea pigs Abs: The mutagenic effect of intraperitoneally injected K2Cr2O7 was significantly higher in vitamin C-deficient guinea pigs than in animals fed diet with high vitamin C content. Mutagenic and toxic effects of hexavalent chromium were more expressed in vitamin C-deficient guinea pigs administered K2Cr2O7 in drinking water: the number of micronuclei in polychromatic erythrocytes of bone marrow was increased, and the activity of O-demethylase and the levels of cytochromes P-450 and b5 in liver microsomes were decreased. In guinea pigs fed high vitamin C diet the same doses of bichromate in drinking water evoked no mutagenic changes in the bone marrow and no changes in microsomal enzymes in the liver. These results indicate that high intake of ascorbic acid in the diet reduces mutagenic effects of K2Cr2O7 and its toxic influence on drug metabolizing enzymes in hepatocytes. The protective effect ascorbic acid consists most probably in the enhanced extracellular and intracellular reduction of hexavalent chromium to the less toxic and less mutagenic trivalent chromium."
1233931,Susa et al. 1989,Induction of lipid peroxidation in mice by hexavalent chromium and its relation to the toxicity,"Comparative effects of hexavalent (K2Cr2O7: Cr(VI)) and trivalent chromium (Cr(NO3)3: Cr(III)) on the development of lipid peroxidation, and the relationship between the lipid peroxidation and damage to tissues were studied using male ddY strain mice. The animals were administered with either of two chemicals at a dose of 20mg Cr/kg by a single intraperitoneal injection. The results obtained were as follows: (1) Lipid peroxidation in the liver, as measured by the synthesis of thiobarbituric acid reactive substances (TBARS), showed a significant increase at 24 and 48 hr after Cr(VI) injection, while in the kidney it was observed only at 48 hr. In the mice administered with Cr(III), TBARS formation in the liver went down below the control levels, while no change was observed in the kidney. (2) Chromium contents in the liver and kidney showed a maximum level at 6 hr after injection of Cr(VI) and then those declined to the half of the maximum level at 48hr, respectively. Chromium contents in the liver and kidney of the mice injected with Cr(III) were lower than those injected with Cr(VI) during the experimental period. (3) Increases of TBARS formation in the liver, chromium content in the liver and kidney, and ornithine carbamyl transferase (OCT) activity indicative of the liver cell damage, and urea nitrogen content in the serum, indicative of the kidney damage, observed at 24 hr after injection of Cr(VI) were inhibited by simultaneous injection of 100mg/kg of L-ascorbic acid, as antichrome agent, respectively. These observations might suggest a possible causative role of lipid peroxidation in Cr(VI) toxicity. (4) Incremental formation of TBARS in the liver after Cr(VI) injection was inhibited by simultaneous injection of N, N-diphenyl-p-phenylenediamine (DPPD), an antioxidant, but DPPD did not suppress the increase of chromium content of the organs examined (the liver and kidney), serum OCT activity and urea nitrogen content observed after Cr(VI) injection. This finding contradicted with the conclusion described above. The results of this study confirmed Cr(VI) induces lipid peroxidatioin in the liver and kidney of the mice, while lipid peroxidation is not responsible for the tissue damage induced by Cr(VI)","Induction of lipid peroxidation in mice by hexavalent chromium and its relation to the toxicity Abs: Comparative effects of hexavalent (K2Cr2O7: Cr(VI)) and trivalent chromium (Cr(NO3)3: Cr(III)) on the development of lipid peroxidation, and the relationship between the lipid peroxidation and damage to tissues were studied using male ddY strain mice. The animals were administered with either of two chemicals at a dose of 20mg Cr/kg by a single intraperitoneal injection. The results obtained were as follows: (1) Lipid peroxidation in the liver, as measured by the synthesis of thiobarbituric acid reactive substances (TBARS), showed a significant increase at 24 and 48 hr after Cr(VI) injection, while in the kidney it was observed only at 48 hr. In the mice administered with Cr(III), TBARS formation in the liver went down below the control levels, while no change was observed in the kidney. (2) Chromium contents in the liver and kidney showed a maximum level at 6 hr after injection of Cr(VI) and then those declined to the half of the maximum level at 48hr, respectively. Chromium contents in the liver and kidney of the mice injected with Cr(III) were lower than those injected with Cr(VI) during the experimental period. (3) Increases of TBARS formation in the liver, chromium content in the liver and kidney, and ornithine carbamyl transferase (OCT) activity indicative of the liver cell damage, and urea nitrogen content in the serum, indicative of the kidney damage, observed at 24 hr after injection of Cr(VI) were inhibited by simultaneous injection of 100mg/kg of L-ascorbic acid, as antichrome agent, respectively. These observations might suggest a possible causative role of lipid peroxidation in Cr(VI) toxicity. (4) Incremental formation of TBARS in the liver after Cr(VI) injection was inhibited by simultaneous injection of N, N-diphenyl-p-phenylenediamine (DPPD), an antioxidant, but DPPD did not suppress the increase of chromium content of the organs examined (the liver and kidney), serum OCT activity and urea nitrogen content observed after Cr(VI) injection. This finding contradicted with the conclusion described above. The results of this study confirmed Cr(VI) induces lipid peroxidatioin in the liver and kidney of the mice, while lipid peroxidation is not responsible for the tissue damage induced by Cr(VI)"
1233929,Katz and  Salem 1989,Inorganic chemistry of chromium and its speciation in Whetlerite,"Chromium compounds are among the impregnants that enhance the ability of carbon air filters to absorb and destroy toxic agents such as CK and AC. The possibility of inhaling chromium-containing carbon dust from such filters has caused concern because, in addition to being an essential nutrient, chromium has been identified as a chemical carcinogen in humans. The essentiality or carcinogenicity of chromium depends upon its chemical speciation. Solubility and oxidation state are particularly important factors in assessing the potential hazards associated with the possible inhalation of chromium-containing dusts from these impregnated carbons or Whetlerites. The chemical speciation of the chromium in Whetlerite was found to be: from 0.6 to 1.3% insoluble trivalent chromium; from 1.0 to 1.3% insoluble hexavalent chromium; and from 0.7 to 0.9% soluble hexavalent chromium. The impregnation process, and the resulting speciation of chromium in Whetlerite, is consistent with the inorganic chemistry of chromium.","Inorganic chemistry of chromium and its speciation in Whetlerite Abs: Chromium compounds are among the impregnants that enhance the ability of carbon air filters to absorb and destroy toxic agents such as CK and AC. The possibility of inhaling chromium-containing carbon dust from such filters has caused concern because, in addition to being an essential nutrient, chromium has been identified as a chemical carcinogen in humans. The essentiality or carcinogenicity of chromium depends upon its chemical speciation. Solubility and oxidation state are particularly important factors in assessing the potential hazards associated with the possible inhalation of chromium-containing dusts from these impregnated carbons or Whetlerites. The chemical speciation of the chromium in Whetlerite was found to be: from 0.6 to 1.3% insoluble trivalent chromium; from 1.0 to 1.3% insoluble hexavalent chromium; and from 0.7 to 0.9% soluble hexavalent chromium. The impregnation process, and the resulting speciation of chromium in Whetlerite, is consistent with the inorganic chemistry of chromium."
1233928,Gibb and  Chen 1989,Evaluation of issues relating to the carcinogen risk assessment of chromium,"Important issues in the carcinogenic risk assessment of chromium compounds are whether both trivalent and hexavalent chromium compounds are carcinogenic, the role of solubility in the carcinogenic response, and the carcinogenicity of ingested chromium. Hexavalent chromium compounds are carcinogenic to animals via several routes of exposure, while trivalent chromium compounds, although they demonstrate evidence of genotoxicity, have not been shown in animal studies to be carcinogenic. Workers in chromate production plants, where the risk of lung cancer is elevated, are exposed to both trivalent and hexavalent chromium compounds. A cancer unit risk estimate for Wistar rats exposed to a hexavalent chromium aerosol (sodium dichromate) is less than the risk estimate for workers in chromate production. If this difference is biologically real, a possible explanation may be that trivalent compounds also have a carcinogenic effect. For hexavalent chromium compounds, it is contended that only sparingly soluble hexavalent chromium compounds are carcinogenic. Recent evidence, however, indicates that highly soluble hexavalent chromium compounds are also carcinogenic. Animal ingestion studies have not found trivalent chromium compounds to be carcinogenic by ingestion; hexavalent compounds have not been studied. Research by EPA to address the issue of valence state and solubility with respect to carcinogenicity is currently being conducted.","Evaluation of issues relating to the carcinogen risk assessment of chromium Abs: Important issues in the carcinogenic risk assessment of chromium compounds are whether both trivalent and hexavalent chromium compounds are carcinogenic, the role of solubility in the carcinogenic response, and the carcinogenicity of ingested chromium. Hexavalent chromium compounds are carcinogenic to animals via several routes of exposure, while trivalent chromium compounds, although they demonstrate evidence of genotoxicity, have not been shown in animal studies to be carcinogenic. Workers in chromate production plants, where the risk of lung cancer is elevated, are exposed to both trivalent and hexavalent chromium compounds. A cancer unit risk estimate for Wistar rats exposed to a hexavalent chromium aerosol (sodium dichromate) is less than the risk estimate for workers in chromate production. If this difference is biologically real, a possible explanation may be that trivalent compounds also have a carcinogenic effect. For hexavalent chromium compounds, it is contended that only sparingly soluble hexavalent chromium compounds are carcinogenic. Recent evidence, however, indicates that highly soluble hexavalent chromium compounds are also carcinogenic. Animal ingestion studies have not found trivalent chromium compounds to be carcinogenic by ingestion; hexavalent compounds have not been studied. Research by EPA to address the issue of valence state and solubility with respect to carcinogenicity is currently being conducted."
1233927,Witmer et al. 1989,Mutagenicity and disposition of chromium,"Hexavalent chromium was administered to rats at doses of 20-240 mumol kg-1 for several periods of time, from 2 to 14 days. Lung, liver and blood contained the highest amounts of chromium, as detected by atomic absorption or by ICP, 24 h after cessation of treatment. A maximum of 40% of the dose was recoverable in organs along with feces and urine at this same time period, and chromium in soil (5.6% Cr) was absorbed better than equimolar amounts of the hexavalent chromates of calcium or sodium. The contaminated chromium-containing soil was found to have 30-35% of the chromium in the hexavalent state. The mutagenicity of chromium as tested in the bacterial strain of Salmonella typhimurium (strain TA 104) was decreased when tested without metabolic activation with the addition of leachate (of inexact analysis) from a waste site. When studied by alkaline elution, chromium (5-20 microM) caused single strand breaks as well as DNA-protein crosslinks in A549 lung cells, while with L1210 mouse leukemia cells, only DNA-protein crosslinks were found. Chromium(III) compounds caused no damage to DNA.","Mutagenicity and disposition of chromium Abs: Hexavalent chromium was administered to rats at doses of 20-240 mumol kg-1 for several periods of time, from 2 to 14 days. Lung, liver and blood contained the highest amounts of chromium, as detected by atomic absorption or by ICP, 24 h after cessation of treatment. A maximum of 40% of the dose was recoverable in organs along with feces and urine at this same time period, and chromium in soil (5.6% Cr) was absorbed better than equimolar amounts of the hexavalent chromates of calcium or sodium. The contaminated chromium-containing soil was found to have 30-35% of the chromium in the hexavalent state. The mutagenicity of chromium as tested in the bacterial strain of Salmonella typhimurium (strain TA 104) was decreased when tested without metabolic activation with the addition of leachate (of inexact analysis) from a waste site. When studied by alkaline elution, chromium (5-20 microM) caused single strand breaks as well as DNA-protein crosslinks in A549 lung cells, while with L1210 mouse leukemia cells, only DNA-protein crosslinks were found. Chromium(III) compounds caused no damage to DNA."
1233926,Wetterhahn and  Hamilton 1989,Molecular basis of hexavalent chromium carcinogenicity: effect on gene expression,"The carcinogenicity of chromium(VI) compounds is explained in terms of the ""uptake-reduction"" model. According to this model, chromium (VI) enters cells as the anionic tetrahedral species chromate, CrO4(2-), using normal cellular anion transport systems, such as the sulfate transport system. Redox-active enzymes and small molecules reduce chromium (VI) intracellularly and produce ""reactive intermediates"" capable of damaging cellular constituents. DNA is presumed to be a critical target within the cell; however, chromium (VI) itself is unreactive toward DNA under physiological conditions in vitro. Thus, the ability of chromium(VI) to damage DNA depends on the presence of cellular components capable of producing putative DNA-damaging agents, such as chromium(VI) thioester, chromium(V), chromium(IV), chromium(III), thiyl radical and hydroxyl radical, upon reaction with the chromium(VI). The exact nature of the DNA damage will be strongly dependent on the reactive intermediates produced by cellular components and systems active in chromium(VI) metabolism. The chromium(VI)-induced DNA damage disrupts the normal functioning of DNA in critical cellular processes, including transcription and replication. The effect of chromium(VI)-induced DNA damage on the function of DNA as a template for transcription has been examined in chick embryo liver in vivo. Chromium(VI) induced DNA-protein and DNA interstrand cross-links and suppressed the induction of 5-aminolevulinic acid synthase and cytochrome P-450 mRNA by porphyrinogenic drugs. In contrast, chromium(VI) increased the basal steady-state mRNA levels of these two inducible genes, but had no effect on the steady-state mRNA levels of the constitutive genes, beta-actin, conalbumin and albumin. Nuclear ""run-off"" transcription experiments showed that the effect of chromium(VI) on the steady-state levels of basal and drug-inducible 5-aminolevulinic acid synthase mRNA was principally the result of changes in the transcription rate of the 5-aminolevulinic acid synthase gene. Chromium(VI)-induced changes in gene expression correlated with the presence of DNA interstrand and DNA-protein cross-links, suggesting that chromium(VI)-induced DNA lesions lead to changes in expression of the targeted genes.","Molecular basis of hexavalent chromium carcinogenicity: effect on gene expression Abs: The carcinogenicity of chromium(VI) compounds is explained in terms of the ""uptake-reduction"" model. According to this model, chromium (VI) enters cells as the anionic tetrahedral species chromate, CrO4(2-), using normal cellular anion transport systems, such as the sulfate transport system. Redox-active enzymes and small molecules reduce chromium (VI) intracellularly and produce ""reactive intermediates"" capable of damaging cellular constituents. DNA is presumed to be a critical target within the cell; however, chromium (VI) itself is unreactive toward DNA under physiological conditions in vitro. Thus, the ability of chromium(VI) to damage DNA depends on the presence of cellular components capable of producing putative DNA-damaging agents, such as chromium(VI) thioester, chromium(V), chromium(IV), chromium(III), thiyl radical and hydroxyl radical, upon reaction with the chromium(VI). The exact nature of the DNA damage will be strongly dependent on the reactive intermediates produced by cellular components and systems active in chromium(VI) metabolism. The chromium(VI)-induced DNA damage disrupts the normal functioning of DNA in critical cellular processes, including transcription and replication. The effect of chromium(VI)-induced DNA damage on the function of DNA as a template for transcription has been examined in chick embryo liver in vivo. Chromium(VI) induced DNA-protein and DNA interstrand cross-links and suppressed the induction of 5-aminolevulinic acid synthase and cytochrome P-450 mRNA by porphyrinogenic drugs. In contrast, chromium(VI) increased the basal steady-state mRNA levels of these two inducible genes, but had no effect on the steady-state mRNA levels of the constitutive genes, beta-actin, conalbumin and albumin. Nuclear ""run-off"" transcription experiments showed that the effect of chromium(VI) on the steady-state levels of basal and drug-inducible 5-aminolevulinic acid synthase mRNA was principally the result of changes in the transcription rate of the 5-aminolevulinic acid synthase gene. Chromium(VI)-induced changes in gene expression correlated with the presence of DNA interstrand and DNA-protein cross-links, suggesting that chromium(VI)-induced DNA lesions lead to changes in expression of the targeted genes."
1233925,Wang et al. 1989,Isolation and Characterization of an Enterobacter cloacae Strain That Reduces Hexavalent Chromium under Anaerobic Conditions,"An Enterobacter cloacae strain (HO1) capable of reducing hexavalent chromium (chromate) was isolated from activated sludge. This bacterium was resistant to chromate under both aerobic and anaerobic conditions. Only the anaerobic culture of the E. cloacae isolate showed chromate reduction. In the anaerobic culture, yellow turned white with chromate and the turbidity increased as the reduction proceeded, suggesting that insoluble chromium hydroxide was formed. E. cloacae is likely to utilize toxic chromate as an electron acceptor anaerobically because (i) the anaerobic growth of E. cloacae HO1 accompanied the decrease of toxic chromate in culture medium, (ii) the chromate-reducing activity was rapidly inhibited by oxygen, and (iii) the reduction occurred more rapidly in glycerol- or acetate-grown cells than in glucose-grown cells. The chromate reduction in E. cloacae HO1 was observed at pH 6.0 to 8.5 (optimum pH, 7.0) and at 10 to 40 degrees C (optimum, 30 degrees C).","Isolation and Characterization of an Enterobacter cloacae Strain That Reduces Hexavalent Chromium under Anaerobic Conditions Abs: An Enterobacter cloacae strain (HO1) capable of reducing hexavalent chromium (chromate) was isolated from activated sludge. This bacterium was resistant to chromate under both aerobic and anaerobic conditions. Only the anaerobic culture of the E. cloacae isolate showed chromate reduction. In the anaerobic culture, yellow turned white with chromate and the turbidity increased as the reduction proceeded, suggesting that insoluble chromium hydroxide was formed. E. cloacae is likely to utilize toxic chromate as an electron acceptor anaerobically because (i) the anaerobic growth of E. cloacae HO1 accompanied the decrease of toxic chromate in culture medium, (ii) the chromate-reducing activity was rapidly inhibited by oxygen, and (iii) the reduction occurred more rapidly in glycerol- or acetate-grown cells than in glucose-grown cells. The chromate reduction in E. cloacae HO1 was observed at pH 6.0 to 8.5 (optimum pH, 7.0) and at 10 to 40 degrees C (optimum, 30 degrees C)."
1233923,Briggs and  Briggs 1989,The in vitro transformation of a rat liver epithelial cell line with chromium,"The transformation of a rat liver epithelial cell line under a wide range of doses of chromium was determined by anchorage-independent growth and tumor formation in syngeneic animals. Chronic exposure to low concentrations and brief exposure to high concentrations of hexavalent chromium (K2CrO4) transformed the cells, but one dose (1 mM K2CrO4, 2 h) was clearly optimal in this regard. The cytotoxicity, effects on cell cycle, rates of chromium uptake, and mutagenic activity under the different treatment conditions were evaluated. The results showed that cells could adapt to the presence of chromium under certain treatment conditions, but this was not the case for the optimal transforming dose. Cells treated with chromium above the optimal transforming dose showed evidence of a transient G2 arrest, whereas all lower levels of treatment did not. A low level continuous exposure to chromate was mutagenic, whereas high level short exposures, including the optimal transforming dose, were not. An increase in the amount of protein complexed with isolated nucleic acids was detected in cells following treatment with the optimal transforming dose of chromate. The results indicate that the effects of chromium on this in vitro system vary with dose, and the identification of those events relevant to metal carcinogenesis will require consideration of treatment conditions.","The in vitro transformation of a rat liver epithelial cell line with chromium Abs: The transformation of a rat liver epithelial cell line under a wide range of doses of chromium was determined by anchorage-independent growth and tumor formation in syngeneic animals. Chronic exposure to low concentrations and brief exposure to high concentrations of hexavalent chromium (K2CrO4) transformed the cells, but one dose (1 mM K2CrO4, 2 h) was clearly optimal in this regard. The cytotoxicity, effects on cell cycle, rates of chromium uptake, and mutagenic activity under the different treatment conditions were evaluated. The results showed that cells could adapt to the presence of chromium under certain treatment conditions, but this was not the case for the optimal transforming dose. Cells treated with chromium above the optimal transforming dose showed evidence of a transient G2 arrest, whereas all lower levels of treatment did not. A low level continuous exposure to chromate was mutagenic, whereas high level short exposures, including the optimal transforming dose, were not. An increase in the amount of protein complexed with isolated nucleic acids was detected in cells following treatment with the optimal transforming dose of chromate. The results indicate that the effects of chromium on this in vitro system vary with dose, and the identification of those events relevant to metal carcinogenesis will require consideration of treatment conditions."
1233922,Bruze et al. 1990,Patch testing with cement containing iron sulfate,"Addition of iron sulfate to cement means transformation of water-soluble hexavalent chromium into nonwater-soluble trivalent chromium. This has been the basis for preventive measures concerning sensitization to hexavalent chromium (chromate) in cement. For some years, iron sulfate has been added to cement manufactured in the Scandinavian countries. In the present in vivo study, cements with and without iron sulfate were compared concerning their capacity to elicit allergic patch-test reactions in eight chromate-hypersensitive individuals. No patch-test reactions were obtained from a water extract of cement with iron sulfate when appropriately buffered.","Patch testing with cement containing iron sulfate Abs: Addition of iron sulfate to cement means transformation of water-soluble hexavalent chromium into nonwater-soluble trivalent chromium. This has been the basis for preventive measures concerning sensitization to hexavalent chromium (chromate) in cement. For some years, iron sulfate has been added to cement manufactured in the Scandinavian countries. In the present in vivo study, cements with and without iron sulfate were compared concerning their capacity to elicit allergic patch-test reactions in eight chromate-hypersensitive individuals. No patch-test reactions were obtained from a water extract of cement with iron sulfate when appropriately buffered."
1233920,Pärt 1990,The perfused fish gill preparation in studies of the bioavailability of chemicals,"The bioavailability of chemicals has received considerable attention in aquatic toxicology, and it is generally agreed that information about bioavailability is lacking in many situations. Here an experimental approach that can be used to assess the bioavailability of chemicals to fish is presented. The gills are the primary uptake site of dissolved chemicals in fish. A perfused gill preparation from rainbow trout is described. The preparation allows direct measurements of the absorption rates of chemicals across the gill epithelium. The use of the preparation in bioavailability studies is exemplified by a study of cadmium availability in different water qualities, by the pH-dependent absorption of hexavalent chromium and by a study on the pH-dependent absorption of halogenated phenols across the gills.","The perfused fish gill preparation in studies of the bioavailability of chemicals Abs: The bioavailability of chemicals has received considerable attention in aquatic toxicology, and it is generally agreed that information about bioavailability is lacking in many situations. Here an experimental approach that can be used to assess the bioavailability of chemicals to fish is presented. The gills are the primary uptake site of dissolved chemicals in fish. A perfused gill preparation from rainbow trout is described. The preparation allows direct measurements of the absorption rates of chemicals across the gill epithelium. The use of the preparation in bioavailability studies is exemplified by a study of cadmium availability in different water qualities, by the pH-dependent absorption of hexavalent chromium and by a study on the pH-dependent absorption of halogenated phenols across the gills."
1233917,Al-Hakkak and  Hussain 1990,Comparative toxicity of trivalent and hexavalent chromium compounds in fig moth Ephestia cautella (Walker),"Of the trivalent (CrSO4) and hexavalent (K2Cr2O7) chromium compounds, only the hexavalent produced significant deleterious effects on development and fertility of E. cautella, when eggs were reared on laboratory medium supplemented with different concentrations of these salts.","Comparative toxicity of trivalent and hexavalent chromium compounds in fig moth Ephestia cautella (Walker) Abs: Of the trivalent (CrSO4) and hexavalent (K2Cr2O7) chromium compounds, only the hexavalent produced significant deleterious effects on development and fertility of E. cautella, when eggs were reared on laboratory medium supplemented with different concentrations of these salts."
1233916,Komori et al. 1990,A method for removal of toxic chromium using dialysis-sac cultures of a chromate-reducing strain of Enterobacter cloacae,"A method for removal of toxic hexavalent chromium (chromate: CrO2-4) was developed by use of dialysis-sac cultures of a chromate-reducing strain of Enterobacter cloacae (HO1). E. cloacae strain HO1 cells were put in dialysis (semipermeable membrane) sacs, and the sacs were submerged in water containing toxic CrO2-4. The dialysis sacs allowed CrO2-4 to diffuse into the culture, and CrO2-4 was reduced anaerobically in the dialysis sacs by the E. cloacae cells. Because reduced chromium readily formed insoluble chromium hydroxides in the dialysis sacs, the greater part of reduced chromium was unable to diffuse out through the semipermeable membrane. Thus the dialysis culture of E. cloacae strain HO1 could successfully remove toxic chromium from the surrounding water. If the initial concentration of CrO2-4 was less than 4 mM (208 ppm as chromium), about 90% of the total chromium could be removed from water by the described method.","A method for removal of toxic chromium using dialysis-sac cultures of a chromate-reducing strain of Enterobacter cloacae Abs: A method for removal of toxic hexavalent chromium (chromate: CrO2-4) was developed by use of dialysis-sac cultures of a chromate-reducing strain of Enterobacter cloacae (HO1). E. cloacae strain HO1 cells were put in dialysis (semipermeable membrane) sacs, and the sacs were submerged in water containing toxic CrO2-4. The dialysis sacs allowed CrO2-4 to diffuse into the culture, and CrO2-4 was reduced anaerobically in the dialysis sacs by the E. cloacae cells. Because reduced chromium readily formed insoluble chromium hydroxides in the dialysis sacs, the greater part of reduced chromium was unable to diffuse out through the semipermeable membrane. Thus the dialysis culture of E. cloacae strain HO1 could successfully remove toxic chromium from the surrounding water. If the initial concentration of CrO2-4 was less than 4 mM (208 ppm as chromium), about 90% of the total chromium could be removed from water by the described method."
1233915,Ishibashi et al. 1990,Chromium reduction in Pseudomonas putida,Reduction of hexavalent chromium (chromate) to less-toxic trivalent chromium was studied by using cell suspensions and cell-free supernatant fluids from Pseudomonas putida PRS2000. Chromate reductase activity was associated with soluble protein and not with the membrane fraction. The crude enzyme activity was heat labile and showed a Km of 40 microM CrO4(2-). Neither sulfate nor nitrate affected chromate reduction either in vitro or with intact cells.,Chromium reduction in Pseudomonas putida Abs: Reduction of hexavalent chromium (chromate) to less-toxic trivalent chromium was studied by using cell suspensions and cell-free supernatant fluids from Pseudomonas putida PRS2000. Chromate reductase activity was associated with soluble protein and not with the membrane fraction. The crude enzyme activity was heat labile and showed a Km of 40 microM CrO4(2-). Neither sulfate nor nitrate affected chromate reduction either in vitro or with intact cells.
1233914,Gopal et al. 1990,In vivo recovery of glycogen metabolism in hemolymph and tissues of a freshwater field crab Barytelphusa guerini on exposure to hexavalent chromium,"The in vivo toxic effects of hexavalent chromium (20 mg/liter) on hemolymph glucose, tissue glycogen, total free sugars, and active and total phosphorylases of an edible, freshwater crab Barytelphusa guerini were studied. In a 15-day exposure span followed by a 15-day postexposure recovery, the time-course alterations in these constituent segments of the glycogen metabolism indicate an inconsistent depletion in metabolite levels and elevated enzyme activities during exposure period as well as hyperglycemia. An insignificant recovery was observed in these parameters on the 15th day of the postexposure phase.","In vivo recovery of glycogen metabolism in hemolymph and tissues of a freshwater field crab Barytelphusa guerini on exposure to hexavalent chromium Abs: The in vivo toxic effects of hexavalent chromium (20 mg/liter) on hemolymph glucose, tissue glycogen, total free sugars, and active and total phosphorylases of an edible, freshwater crab Barytelphusa guerini were studied. In a 15-day exposure span followed by a 15-day postexposure recovery, the time-course alterations in these constituent segments of the glycogen metabolism indicate an inconsistent depletion in metabolite levels and elevated enzyme activities during exposure period as well as hyperglycemia. An insignificant recovery was observed in these parameters on the 15th day of the postexposure phase."
1233913,Vreeburg et al. 1990,Oral induction of immunological tolerance to chromium in the guinea pig,"Metal alloys used in dentistry may elicit adverse side-effects. Contact allergic reactions to metals released from such alloys are among the most frequently encountered problems. In an earlier study, we observed that oral contacts with nickel or chromium salts did not sensitize, but rather decreased the risk of subsequent sensitization to these metals. In the present study, we focused on chromium allergy and extended our earlier observations by further dose-response studies. In addition, we compared different chromium valencies as to their potential oral tolerogenic effects. Development of immunological tolerance in chromium-fed guinea pigs was demonstrated by their inability to develop chromium hypersensitivity after a subsequent immunization attempt. For these studies, the techniques of immunization and skin testing were first improved. One feeding with a high dose of K2Cr2O7 (containing hexavalent chromium) was effective in full tolerance induction. In contrast, trivalent chromium (CrCl3) induced a distinctly lower degree of tolerance, whereas metallic chromium powder was not detectably tolerogenic after a limited number of feedings. Dose-frequency-response studies with K2Cr2O7 showed that full tolerance could also be induced by an increase in the number of feedings with sub-optimal tolerogenic doses. The present results therefore support our hypothesis that long-lasting oral contact with chromium-releasing metal alloys may ultimately result in strong immune tolerance to this metal in subjects without previous skin contact with it. This view is further supported by recent insights into the unique tolerogenicity of oral, as compared with gastro-intestinal, allergenic contacts.","Oral induction of immunological tolerance to chromium in the guinea pig Abs: Metal alloys used in dentistry may elicit adverse side-effects. Contact allergic reactions to metals released from such alloys are among the most frequently encountered problems. In an earlier study, we observed that oral contacts with nickel or chromium salts did not sensitize, but rather decreased the risk of subsequent sensitization to these metals. In the present study, we focused on chromium allergy and extended our earlier observations by further dose-response studies. In addition, we compared different chromium valencies as to their potential oral tolerogenic effects. Development of immunological tolerance in chromium-fed guinea pigs was demonstrated by their inability to develop chromium hypersensitivity after a subsequent immunization attempt. For these studies, the techniques of immunization and skin testing were first improved. One feeding with a high dose of K2Cr2O7 (containing hexavalent chromium) was effective in full tolerance induction. In contrast, trivalent chromium (CrCl3) induced a distinctly lower degree of tolerance, whereas metallic chromium powder was not detectably tolerogenic after a limited number of feedings. Dose-frequency-response studies with K2Cr2O7 showed that full tolerance could also be induced by an increase in the number of feedings with sub-optimal tolerogenic doses. The present results therefore support our hypothesis that long-lasting oral contact with chromium-releasing metal alloys may ultimately result in strong immune tolerance to this metal in subjects without previous skin contact with it. This view is further supported by recent insights into the unique tolerogenicity of oral, as compared with gastro-intestinal, allergenic contacts."
1233912,Saxena et al. 1990,Fetoplacental-maternal uptake of hexavalent chromium administered orally in rats and mice,,Fetoplacental-maternal uptake of hexavalent chromium administered orally in rats and mice Abs: 
1233911,Kim and  Na 1990,Acute toxic effect of sodium dichromate on metabolism,"The effect of sodium dichromate on cellular metabolism was investigated. Intraperitoneal injection of sodium dichromate into the rat (20 or 40 mg/kg) caused significant increases in serum lactate, pyruvate, and creatinine concentrations within 15 min after intoxication. Severe hyperglycemia occurred thereafter, as a result of increased hepatic glycogenolysis, which was seen in the first 2 h after dichromate. However, liver glycogen was resynthesized in 24 h-fasted rats after glucose refeeding. Dichromate decreased serum total amino acids, with a consequent increase in blood urea nitrogen (BUN) concentration. Unlike HgCl2 (2 mg/kg, i.p.), As2O3 (5 mg/kg, i.p.), and KCN (5 mg/kg, i.p.), dichromate showed the largest metabolic disturbance only in the early period after treatment. In addition, dichromate produced cyanosis, which appeared during the period of the accelerated glycolysis and breakdown of creatinine phosphate. Regardless of chemical species, only the hexavalent chromium compounds had an effect on the cellular metabolism. Trivalent chromium compounds had no effect at all. These results suggest that dichromate possesses a characteristic dual action on cellular metabolism, which might be related to its metabolic fate.","Acute toxic effect of sodium dichromate on metabolism Abs: The effect of sodium dichromate on cellular metabolism was investigated. Intraperitoneal injection of sodium dichromate into the rat (20 or 40 mg/kg) caused significant increases in serum lactate, pyruvate, and creatinine concentrations within 15 min after intoxication. Severe hyperglycemia occurred thereafter, as a result of increased hepatic glycogenolysis, which was seen in the first 2 h after dichromate. However, liver glycogen was resynthesized in 24 h-fasted rats after glucose refeeding. Dichromate decreased serum total amino acids, with a consequent increase in blood urea nitrogen (BUN) concentration. Unlike HgCl2 (2 mg/kg, i.p.), As2O3 (5 mg/kg, i.p.), and KCN (5 mg/kg, i.p.), dichromate showed the largest metabolic disturbance only in the early period after treatment. In addition, dichromate produced cyanosis, which appeared during the period of the accelerated glycolysis and breakdown of creatinine phosphate. Regardless of chemical species, only the hexavalent chromium compounds had an effect on the cellular metabolism. Trivalent chromium compounds had no effect at all. These results suggest that dichromate possesses a characteristic dual action on cellular metabolism, which might be related to its metabolic fate."
1233907,Saxena et al. 1990,Effect of hexavalent chromium on testicular maturation in the rat,"Daily intraperitoneal administration of hexavalent chromium (Cr6+; 1, 2, and 3 mg/kg intraperitoneally as potassium dichromate) in weaned rats for an entire duration of 55 and 90 days of age produced dose- and duration-dependent enzymatic and pathologic alterations. At 55 days, the pathologic changes were not seen in testes of Cr6+ treated rats, but the activities of sorbitol dehydrogenase, lactic dehydrogenase, gamma-glutamyl transpeptidase, and glucose-6-phosphate dehydrogenase were significantly altered. When the treatment was prolonged to sexual maturity, that is, 90 days of age, the alterations in enzyme activities were greater, and there were dose-dependent pathologic changes in the testes of Cr(6+)-treated rats. These alterations suggest a risk to growing testes if rats are exposed to Cr6+ during the prepubertal stage of development, which, in turn, may disturb normal testicular physiology at adulthood.","Effect of hexavalent chromium on testicular maturation in the rat Abs: Daily intraperitoneal administration of hexavalent chromium (Cr6+; 1, 2, and 3 mg/kg intraperitoneally as potassium dichromate) in weaned rats for an entire duration of 55 and 90 days of age produced dose- and duration-dependent enzymatic and pathologic alterations. At 55 days, the pathologic changes were not seen in testes of Cr6+ treated rats, but the activities of sorbitol dehydrogenase, lactic dehydrogenase, gamma-glutamyl transpeptidase, and glucose-6-phosphate dehydrogenase were significantly altered. When the treatment was prolonged to sexual maturity, that is, 90 days of age, the alterations in enzyme activities were greater, and there were dose-dependent pathologic changes in the testes of Cr(6+)-treated rats. These alterations suggest a risk to growing testes if rats are exposed to Cr6+ during the prepubertal stage of development, which, in turn, may disturb normal testicular physiology at adulthood."
1233904,Chorvatovicová et al. 1991,Effect of vitamins C and E on toxicity and mutagenicity of hexavalent chromium in rat and guinea pig,"The effect of simultaneous pretreatment with vitamins C and E on the toxicity and mutagenicity of K2Cr2O7 in rats and guinea pigs was evaluated. Dietary pretreatment of Cr(VI)-intoxicated rats with ascorbic acid or alpha-tocopherol normalized vitamin C levels in lungs but not in kidneys. The synergistic preventive effect of both vitamins was confirmed in the production of lipoperoxides in Cr(VI)-intoxicated rats. Simultaneous administration of vitamins C and E in guinea pigs prevented the decrease of vitamin C levels provoked by the oxidative effects of Cr(VI). The results of the micronucleus test in bone marrow showed that it was vitamin C that caused the antimutagenic effect against bichromate, in both rats and guinea pigs. The effect of vitamin E was demonstrated only in an increase of the ratio of NCE to PCE, i.e., in a decrease of the cytotoxic but not the mutagenic effects of hexavalent chromium.","Effect of vitamins C and E on toxicity and mutagenicity of hexavalent chromium in rat and guinea pig Abs: The effect of simultaneous pretreatment with vitamins C and E on the toxicity and mutagenicity of K2Cr2O7 in rats and guinea pigs was evaluated. Dietary pretreatment of Cr(VI)-intoxicated rats with ascorbic acid or alpha-tocopherol normalized vitamin C levels in lungs but not in kidneys. The synergistic preventive effect of both vitamins was confirmed in the production of lipoperoxides in Cr(VI)-intoxicated rats. Simultaneous administration of vitamins C and E in guinea pigs prevented the decrease of vitamin C levels provoked by the oxidative effects of Cr(VI). The results of the micronucleus test in bone marrow showed that it was vitamin C that caused the antimutagenic effect against bichromate, in both rats and guinea pigs. The effect of vitamin E was demonstrated only in an increase of the ratio of NCE to PCE, i.e., in a decrease of the cytotoxic but not the mutagenic effects of hexavalent chromium."
1233903,Coogan et al. 1991,Distribution of chromium within cells of the blood,"Although a number of investigators have examined the uptake of chromium in red blood cells (RBC) or whole blood, little is known about chromium uptake in white blood cells (WBC). Radiolabeled chromium (51Cr) was used to determine chromium uptake and distribution. Isolated RBC and enriched WBC populations were exposed in vitro to potassium chromate (Cr+6) and uptake was determined over a 2-hr time period. Exposure of either rat or human blood cells to 50 microM K2CrO4 for 2 hr resulted in greater accumulation of chromium within WBC than RBC. Uptake by rat WBC was significantly greater than that of human; whereas, uptake by human RBC was greater than that of the rat. Exposure of human whole blood to 50 microM K2CrO4, prior to isolation of WBC, also resulted in an increased uptake of chromium by WBC. Fisher 344 rats were exposed either orally or intravenously to a single dose of K2CrO4 and the distribution of chromium within blood cells was determined 1 hr, 24 hr, or 7 days following exposure. Regardless of the route or time following exposure, WBC chromium levels were consistently greater than those of RBC. However, the absolute levels of chromium did change with time. A comparison of chromium distribution 24 hr following a single oral exposure (1 ppm Cr+6) to the distribution 7 days following exposure demonstrated a reduction in chromium levels for RBC (10-fold) and for WBC (approximately 2.5-fold). In contrast, intravenous administration of chromate resulted in no significant decrease in RBC chromium levels when compared 1 hr, 24 hr, and 7 days following exposure. Although no difference in WBC chromium content was observed at 1 and 24 hr after exposure, an approximate 1.7-fold decrease in chromium content was detected at Day 7 for WBC. Intravenous administration of chromic chloride (Cr+3) resulted in a low level of chromium associated with RBC following 1 hr, and chromium was undetected in the WBC. These data demonstrate that WBC accumulate hexavalent chromium following both in vitro and in vivo exposure. In addition, white blood cells accumulate chromium to a greater extent than red blood cells. Since WBC accumulate chromium, their use as a target for the development of biomarkers of chromium exposure may be warranted.","Distribution of chromium within cells of the blood Abs: Although a number of investigators have examined the uptake of chromium in red blood cells (RBC) or whole blood, little is known about chromium uptake in white blood cells (WBC). Radiolabeled chromium (51Cr) was used to determine chromium uptake and distribution. Isolated RBC and enriched WBC populations were exposed in vitro to potassium chromate (Cr+6) and uptake was determined over a 2-hr time period. Exposure of either rat or human blood cells to 50 microM K2CrO4 for 2 hr resulted in greater accumulation of chromium within WBC than RBC. Uptake by rat WBC was significantly greater than that of human; whereas, uptake by human RBC was greater than that of the rat. Exposure of human whole blood to 50 microM K2CrO4, prior to isolation of WBC, also resulted in an increased uptake of chromium by WBC. Fisher 344 rats were exposed either orally or intravenously to a single dose of K2CrO4 and the distribution of chromium within blood cells was determined 1 hr, 24 hr, or 7 days following exposure. Regardless of the route or time following exposure, WBC chromium levels were consistently greater than those of RBC. However, the absolute levels of chromium did change with time. A comparison of chromium distribution 24 hr following a single oral exposure (1 ppm Cr+6) to the distribution 7 days following exposure demonstrated a reduction in chromium levels for RBC (10-fold) and for WBC (approximately 2.5-fold). In contrast, intravenous administration of chromate resulted in no significant decrease in RBC chromium levels when compared 1 hr, 24 hr, and 7 days following exposure. Although no difference in WBC chromium content was observed at 1 and 24 hr after exposure, an approximate 1.7-fold decrease in chromium content was detected at Day 7 for WBC. Intravenous administration of chromic chloride (Cr+3) resulted in a low level of chromium associated with RBC following 1 hr, and chromium was undetected in the WBC. These data demonstrate that WBC accumulate hexavalent chromium following both in vitro and in vivo exposure. In addition, white blood cells accumulate chromium to a greater extent than red blood cells. Since WBC accumulate chromium, their use as a target for the development of biomarkers of chromium exposure may be warranted."
1233902,Wass and  Wahlberg 1991,Chromated steel and contact allergy. Recommendation concerning a &quot;threshold limit value&quot; for the release of hexavalent chromium,"Steel surfaces can be treated with zinc and chromates to prevent the steel from rusting. Cases of allergic contact dermatitis due to the release of hexavalent chromium (Cr64) from chromated surfaces have been reported. The main purpose of the present study was to develop a simple procedure for the determination of leachable Cr64 that could be used in industrial applications to check the quality of chromated products and to establish a &quot;threshold limit value&quot; for such products. Occlusive tests were performed in chromate-sensitive patients using chromated discs, and discs representing a release of 0.6 microgram/cm2 or more elicited positive results in all patients tested. It was proposed that the mean release of Cr64 from chromated parts should not exceed 0.3 microgram/cm2. Approximately 1 out of 4 yellow chromated parts, collected from a chromating plant and a car assembly plant, gave values above this limit. Today, several tests are performed to evaluate the technical quality of the chromate layers. It is suggested that the present method should be added to the test program in order to reduce the risk of causing chromate allergy.","Chromated steel and contact allergy. Recommendation concerning a &quot;threshold limit value&quot; for the release of hexavalent chromium Abs: Steel surfaces can be treated with zinc and chromates to prevent the steel from rusting. Cases of allergic contact dermatitis due to the release of hexavalent chromium (Cr64) from chromated surfaces have been reported. The main purpose of the present study was to develop a simple procedure for the determination of leachable Cr64 that could be used in industrial applications to check the quality of chromated products and to establish a &quot;threshold limit value&quot; for such products. Occlusive tests were performed in chromate-sensitive patients using chromated discs, and discs representing a release of 0.6 microgram/cm2 or more elicited positive results in all patients tested. It was proposed that the mean release of Cr64 from chromated parts should not exceed 0.3 microgram/cm2. Approximately 1 out of 4 yellow chromated parts, collected from a chromating plant and a car assembly plant, gave values above this limit. Today, several tests are performed to evaluate the technical quality of the chromate layers. It is suggested that the present method should be added to the test program in order to reduce the risk of causing chromate allergy."
1233901,Kumar and  Barthwal 1991,Hexavalent chromium effects on hematological indices in rats,"The effects of chromium-VI (7440473) on hematological indices in rats were investigated. In addition to receiving pellet diet, three groups of rats were fed by gavage with chromium-VI in the form of potassium-chromate (7789006) at 0.05 grams/kilogram on each day for 7, 15, and 30 days, respectively. Rats in a fourth group served as controls. After scheduled treatment the rats were starved for 24 hours and then sacrificed. The rats were active during the investigation and there were no overt signs of toxicosis although reduced weight gain was evident. Chromium-VI induced changes were noted in hematological indices, with the rats treated for the longer time periods experiencing the greater changes. The level of serum triglycerides, phospholipids, cholesterol and glucose were elevated significantly in rats fed on chromium-VI for 30 days. Significant increases were noted in serum urea levels, which served as an indication of renal damage. Significant increases were noted in glutamic oxaloacetic-transaminase and glutamic pyruvic-transaminase activities, which were indicative of liver dysfunction. Plasma activity of glutamate-dehydrogenase, an index of mitochondrial injury, was significantly elevated in rats exposed to chromium-VI for 30 days. An insignificant stimulation was also noted after 7 and 15 days of treatment. A marked increase in lactate-dehydrogenase activity was reported.","Hexavalent chromium effects on hematological indices in rats Abs: The effects of chromium-VI (7440473) on hematological indices in rats were investigated. In addition to receiving pellet diet, three groups of rats were fed by gavage with chromium-VI in the form of potassium-chromate (7789006) at 0.05 grams/kilogram on each day for 7, 15, and 30 days, respectively. Rats in a fourth group served as controls. After scheduled treatment the rats were starved for 24 hours and then sacrificed. The rats were active during the investigation and there were no overt signs of toxicosis although reduced weight gain was evident. Chromium-VI induced changes were noted in hematological indices, with the rats treated for the longer time periods experiencing the greater changes. The level of serum triglycerides, phospholipids, cholesterol and glucose were elevated significantly in rats fed on chromium-VI for 30 days. Significant increases were noted in serum urea levels, which served as an indication of renal damage. Significant increases were noted in glutamic oxaloacetic-transaminase and glutamic pyruvic-transaminase activities, which were indicative of liver dysfunction. Plasma activity of glutamate-dehydrogenase, an index of mitochondrial injury, was significantly elevated in rats exposed to chromium-VI for 30 days. An insignificant stimulation was also noted after 7 and 15 days of treatment. A marked increase in lactate-dehydrogenase activity was reported."
1233899,Bonde and  Christensen 1991,Chromium in biological samples from low-level exposed stainless steel and mild steel welders,"Occupational exposure to hexavalent chromium is of concern because of the carcinogenic action of this metal. The purpose of this study was to evaluate internal exposure to chromium in welders who were exposed to low levels of chromium. Chromium in urine, blood, and seminal fluid was determined among 60 welders and 45 referents. The concentration of chromium in urine and blood did not change across a workshift or across a 3-wk break in exposure. However, stainless-steel and mild-steel welders who were exposed to low levels of chromium and steel welders who were mildly exposed had significantly increased levels of chromium in post-shift urine (mean 2.1 nmol/mmol creatinine [standard deviation (SD) = 1.0] and 1.3 nmol/mmol creatinine [SD = 0.5], respectively) compared with referents (mean 0.7 nmol/mmol creatinine [SD = 0.3]). Pre-shift blood chromium concentrations showed a similar variation between exposed workers and referents. Subgroups of stainless-steel welders had very high levels of chromium in seminal fluid. This finding may, however, be explained by nonoccupational factors and, therefore, warrants further study. Attention should focus on the potential risk of delayed health effects among stainless-steel and mild-steel welders who heretofore were not thought to be at risk from chromium exposure.","Chromium in biological samples from low-level exposed stainless steel and mild steel welders Abs: Occupational exposure to hexavalent chromium is of concern because of the carcinogenic action of this metal. The purpose of this study was to evaluate internal exposure to chromium in welders who were exposed to low levels of chromium. Chromium in urine, blood, and seminal fluid was determined among 60 welders and 45 referents. The concentration of chromium in urine and blood did not change across a workshift or across a 3-wk break in exposure. However, stainless-steel and mild-steel welders who were exposed to low levels of chromium and steel welders who were mildly exposed had significantly increased levels of chromium in post-shift urine (mean 2.1 nmol/mmol creatinine [standard deviation (SD) = 1.0] and 1.3 nmol/mmol creatinine [SD = 0.5], respectively) compared with referents (mean 0.7 nmol/mmol creatinine [SD = 0.3]). Pre-shift blood chromium concentrations showed a similar variation between exposed workers and referents. Subgroups of stainless-steel welders had very high levels of chromium in seminal fluid. This finding may, however, be explained by nonoccupational factors and, therefore, warrants further study. Attention should focus on the potential risk of delayed health effects among stainless-steel and mild-steel welders who heretofore were not thought to be at risk from chromium exposure."
1233898,Nair and  Krishnamurthi 1991,Effect of chromium on growth of Pseudomonas aeruginosa,"Tolerance level to trivalent chromium-Cr(salen)(H2O)2+ and hexavalent chromium-K2Cr2O7 was assessed in P. aeruginosa isolated from tannery effluent soil. It could tolerate 80 and 100 ppm in liquid cultures and up to 100 and 200 ppm in plate count agar in the presence of trivalent and hexavalent chromium respectively. Unadapted cells took a longer time to grow than adapted cells in the presence of K2Cr2O7. Chromium influenced the cellular contents, morphology and respiration of P. aeruginosa. The chosen trivalent salt of chromium was more toxic than the hexavalent one.","Effect of chromium on growth of Pseudomonas aeruginosa Abs: Tolerance level to trivalent chromium-Cr(salen)(H2O)2+ and hexavalent chromium-K2Cr2O7 was assessed in P. aeruginosa isolated from tannery effluent soil. It could tolerate 80 and 100 ppm in liquid cultures and up to 100 and 200 ppm in plate count agar in the presence of trivalent and hexavalent chromium respectively. Unadapted cells took a longer time to grow than adapted cells in the presence of K2Cr2O7. Chromium influenced the cellular contents, morphology and respiration of P. aeruginosa. The chosen trivalent salt of chromium was more toxic than the hexavalent one."
1233897,Arar and  Pfaff 1991,Determination of dissolved hexavalent chromium in industrial wastewater effluents by ion chromatography and post-column derivatization with diphenylcarbazide,"A proposed EPA method for the determination of dissolved hexavalent chromium in drinking water, groundwater and industrial wastewater effluents was developed using existing ion chromatographic techniques. Two solid waste matrices were briefly investigated. Aqueous samples were passed through a 0.45-micron filter and the filtrate was either (1) left unadjusted, (2) adjusted to pH 8 or (3) adjusted to pH 10 prior to analysis by ion chromatography. The method detection limits were 0.3-0.4 micrograms/l. When analyzed within 24 h, the two pH levels and the unadjusted sample yielded ca. 100% recovery of spikes. No oxidation of trivalent chromium to hexavalent chromium was observed at pH 7, 8 or 10 when aqueous samples were spiked with 50 mg/l Cr(III).","Determination of dissolved hexavalent chromium in industrial wastewater effluents by ion chromatography and post-column derivatization with diphenylcarbazide Abs: A proposed EPA method for the determination of dissolved hexavalent chromium in drinking water, groundwater and industrial wastewater effluents was developed using existing ion chromatographic techniques. Two solid waste matrices were briefly investigated. Aqueous samples were passed through a 0.45-micron filter and the filtrate was either (1) left unadjusted, (2) adjusted to pH 8 or (3) adjusted to pH 10 prior to analysis by ion chromatography. The method detection limits were 0.3-0.4 micrograms/l. When analyzed within 24 h, the two pH levels and the unadjusted sample yielded ca. 100% recovery of spikes. No oxidation of trivalent chromium to hexavalent chromium was observed at pH 7, 8 or 10 when aqueous samples were spiked with 50 mg/l Cr(III)."
1233895,Palmer and  Wittbrodt 1991,Processes affecting the remediation of chromium-contaminated sites,"The remediation of chromium-contaminated sites requires knowledge of the processes that control the migration and transformation of chromium. Advection, dispersion, and diffusion are physical processes affecting the rate at which contaminants can migrate in the subsurface. Heterogeneity is an important factor that affects the contribution of each of these mechanisms to the migration of chromium-laden waters. Redox reactions, chemical speciation, adsorption/desorption phenomena, and precipitation/dissolution reactions control the transformation and mobility of chromium. The reduction of CrVI to CrIII can occur in the presence of ferrous iron in solution or in mineral phases, reduced sulfur compounds, or soil organic matter. At neutral to alkaline pH, the CrIII precipitates as amorphous hydroxides or forms complexes with organic matter. CrIII is oxidized by manganese dioxide, a common mineral found in many soils. Solid-phase precipitates of hexavalent chromium such as barium chromate can serve either as sources or sinks for CrVI. Adsorption of CrVI in soils increases with decreasing chromium concentration, making it more difficult to remove the chromium as the concentration decreases during pump-and-treat remediation. Knowledge of these chemical and physical processes is important in developing and selecting effective, cost-efficient remediation designs for chromium-contaminated sites.","Processes affecting the remediation of chromium-contaminated sites Abs: The remediation of chromium-contaminated sites requires knowledge of the processes that control the migration and transformation of chromium. Advection, dispersion, and diffusion are physical processes affecting the rate at which contaminants can migrate in the subsurface. Heterogeneity is an important factor that affects the contribution of each of these mechanisms to the migration of chromium-laden waters. Redox reactions, chemical speciation, adsorption/desorption phenomena, and precipitation/dissolution reactions control the transformation and mobility of chromium. The reduction of CrVI to CrIII can occur in the presence of ferrous iron in solution or in mineral phases, reduced sulfur compounds, or soil organic matter. At neutral to alkaline pH, the CrIII precipitates as amorphous hydroxides or forms complexes with organic matter. CrIII is oxidized by manganese dioxide, a common mineral found in many soils. Solid-phase precipitates of hexavalent chromium such as barium chromate can serve either as sources or sinks for CrVI. Adsorption of CrVI in soils increases with decreasing chromium concentration, making it more difficult to remove the chromium as the concentration decreases during pump-and-treat remediation. Knowledge of these chemical and physical processes is important in developing and selecting effective, cost-efficient remediation designs for chromium-contaminated sites."
1233893,Bagdon and  Hazen 1991,Skin permeation and cutaneous hypersensitivity as a basis for making risk assessments of chromium as a soil contaminant,"A literature review of experimental and human exposure studies of skin permeation and cutaneous hypersensitivity reactions evoked by chromium was carried out to provide a basis for making a risk assessment of chromium as a soil contaminant. In vitro and in vivo studies demonstrated that 1 to 4% of the applied dose of hexavalent and trivalent chromium to guinea pig skin penetrated skin within 5 to 24 hr after application. Ultrastructural investigations showed that hexavalent chromium localized intracellularly and extracellularly in the upper layers of guinea pig epidermis. Only minute quantities of hexavalent chromium are required to elicit a positive hypersensitivity reaction in susceptible individuals; using a patch dose of 20 micrograms, only 2 micrograms were required to evoke a positive skin reaction in hypersensitive subjects. The potential of hexavalent chromium to produce a skin sensitization reaction is readily demonstrated using animal models. The incidence and characteristics of chromium-induced skin hypersensitivity as a clinical entity are described. A health effects survey of populations exposed to chromium slag in soil in Tokyo, Japan extending over 8 years indicated a tendency toward symptoms characterized as headache, chronic fatigue, and gastrointestinal complaints, positive occult blood tests, minute hematuria and albuminuria suggestive of incipient renal disease, and a tendency toward an increase in contact dermatitis that was seasonally related. Multicenter patch test titration studies in human subjects using an incidence of positive patch tests of 10% or less showed that the threshold for skin hypersensitivity reactions to hexavalent chromium was determined to be of the order 0.001%, equivalent to 10 ppm or 10 mg/kg or 10 mg/L.(ABSTRACT TRUNCATED AT 250 WORDS)","Skin permeation and cutaneous hypersensitivity as a basis for making risk assessments of chromium as a soil contaminant Abs: A literature review of experimental and human exposure studies of skin permeation and cutaneous hypersensitivity reactions evoked by chromium was carried out to provide a basis for making a risk assessment of chromium as a soil contaminant. In vitro and in vivo studies demonstrated that 1 to 4% of the applied dose of hexavalent and trivalent chromium to guinea pig skin penetrated skin within 5 to 24 hr after application. Ultrastructural investigations showed that hexavalent chromium localized intracellularly and extracellularly in the upper layers of guinea pig epidermis. Only minute quantities of hexavalent chromium are required to elicit a positive hypersensitivity reaction in susceptible individuals; using a patch dose of 20 micrograms, only 2 micrograms were required to evoke a positive skin reaction in hypersensitive subjects. The potential of hexavalent chromium to produce a skin sensitization reaction is readily demonstrated using animal models. The incidence and characteristics of chromium-induced skin hypersensitivity as a clinical entity are described. A health effects survey of populations exposed to chromium slag in soil in Tokyo, Japan extending over 8 years indicated a tendency toward symptoms characterized as headache, chronic fatigue, and gastrointestinal complaints, positive occult blood tests, minute hematuria and albuminuria suggestive of incipient renal disease, and a tendency toward an increase in contact dermatitis that was seasonally related. Multicenter patch test titration studies in human subjects using an incidence of positive patch tests of 10% or less showed that the threshold for skin hypersensitivity reactions to hexavalent chromium was determined to be of the order 0.001%, equivalent to 10 ppm or 10 mg/kg or 10 mg/L.(ABSTRACT TRUNCATED AT 250 WORDS)"
1233892,Räsänen et al. 1991,Lymphocyte proliferation test as a diagnostic aid in chromium contact sensitivity,"We investigated the clinical applicability of the lymphocyte proliferation test (LPT) in chromium contact sensitivity. 6 out of 8 chromium-sensitive patients were positive in the LPT, whereas none of 8 non-chromium-sensitive controls responded in vitro to tri- or hexavalent chromium compounds. LPT thus appeared to offer an additional diagnostic tool in chromium sensitivity. We also studied cellular interactions in 4 of our chromium-sensitive patients. Sensitized T-lymphocytes could be activated to proliferate only in the presence of accessory cells, of which epidermal Langerhans cells (LC) appeared more efficient than blood adherent cells.","Lymphocyte proliferation test as a diagnostic aid in chromium contact sensitivity Abs: We investigated the clinical applicability of the lymphocyte proliferation test (LPT) in chromium contact sensitivity. 6 out of 8 chromium-sensitive patients were positive in the LPT, whereas none of 8 non-chromium-sensitive controls responded in vitro to tri- or hexavalent chromium compounds. LPT thus appeared to offer an additional diagnostic tool in chromium sensitivity. We also studied cellular interactions in 4 of our chromium-sensitive patients. Sensitized T-lymphocytes could be activated to proliferate only in the presence of accessory cells, of which epidermal Langerhans cells (LC) appeared more efficient than blood adherent cells."
1233891,Nagaya et al. 1991,Sister-chromatid exchanges in lymphocytes from 12 chromium platers: a 5-year follow-up study,"To detect the mutagenic effects of hexavalent chromium (Cr) in humans, sister-chromatid exchange (SCE) frequency in lymphocytes and urinary Cr was determined in 66 blood-urine paired samples from 12 male Cr-platers during 5 years (1984-1989). Multiple regression of SCE frequency on age, urinary Cr and smoking habits was analyzed in all 66 samples. Neither age (P = 0.204) nor urinary Cr (P = 0.056) was a significant predictor for SCE frequency. Although urinalysis revealed obvious exposure to Cr in the platers, exposure was unable to influence SCE frequency. Smoking habits were a highly significant (P less than 0.001) positive predictor for SCE frequency, and smoking of one cigarette per day was associated with an increase of 0.054 SCEs/cell in SCE frequency. SCE frequency significantly fluctuated from year to year in 3 subjects. The smoking habits of these 3 subjects did not change during the follow-up period. The results suggest that there are other unknown factors influencing SCE frequency in addition to smoking habits.","Sister-chromatid exchanges in lymphocytes from 12 chromium platers: a 5-year follow-up study Abs: To detect the mutagenic effects of hexavalent chromium (Cr) in humans, sister-chromatid exchange (SCE) frequency in lymphocytes and urinary Cr was determined in 66 blood-urine paired samples from 12 male Cr-platers during 5 years (1984-1989). Multiple regression of SCE frequency on age, urinary Cr and smoking habits was analyzed in all 66 samples. Neither age (P = 0.204) nor urinary Cr (P = 0.056) was a significant predictor for SCE frequency. Although urinalysis revealed obvious exposure to Cr in the platers, exposure was unable to influence SCE frequency. Smoking habits were a highly significant (P less than 0.001) positive predictor for SCE frequency, and smoking of one cigarette per day was associated with an increase of 0.054 SCEs/cell in SCE frequency. SCE frequency significantly fluctuated from year to year in 3 subjects. The smoking habits of these 3 subjects did not change during the follow-up period. The results suggest that there are other unknown factors influencing SCE frequency in addition to smoking habits."
1233890,Paustenbach et al. 1991,An assessment and quantitative uncertainty analysis of the health risks to workers exposed to chromium contaminated soils,"Millions of tons of chromite-ore processing residue have been used as fill in various locations in Northern New Jersey and elsewhere in the United States. The primary toxicants in the residue are trivalent chromium [Cr(III)] and hexavalent chromium [Cr(VI)]. The hazard posed by Cr(III) is negligible due to its low acute and chronic toxicity. In contrast, Cr(VI) is considered a inhalation human carcinogen at high concentrations. Approximately 40 commercial and industrial properties in Northern New Jersey have been identified as containing chromite ore processing residue in the soil. One site, a partially-paved trucking terminal, was evaluated in this assessment. The arithmetic mean and geometric mean concentrations of total chromium in soil were 977 and 359 mg/kg, respectively. The data were log-normal distributed. The arithmetic mean and geometric mean concentrations of Cr(VI) in surface soil were 37.6 and 3.1 mg/kg, respectively. The data could not be fit to a standard distribution, likely due to the large number of samples with concentrations below the method detection limit (65%). Dose was calculated for each exposure route using a Monte Carlo statistical simulation. Probability distributions of most exposure parameters were incorporated into the analyses to predict the range and probability of uptake for persons in the exposed population. The exposure parameter distributions included in this assessment are: the concentrations of Cr(VI) and total chromium in air and soil, fraction of the year when suspension of airborne soil particulates is likely to occur due to weather conditions, fraction of Cr(VI) in air which is respirable (less than 10 microns), soil loading rate on skin, occupational tenure, and body weight. The techniques used in this assessment are applicable for evaluating the human health risks posed by most industrial sites having contaminated soil. The estimated average daily dose (ADD) via ingestion and dermal absorption for the individual exposed at the 95th percentile was about 48,000- and 91-fold below the U.S. EPA reference dose (RfD) for Cr(III) and Cr(VI), respectively. Since inhalation of Cr(VI) contaminated dust (but not ingestion or dermal contact) poses a cancer hazard, the lifetime average daily doses (LADDs) associated with exposure at the 50th and 95th percentile were calculated to be 9.8 x 10(-8) and 1.3 x 10(-6), respectively. Based on this analysis, industrial sites having soil concentrations of Cr(VI) below 230 ppm do not pose a significant noncarcinogenic or carcinogenic health hazard following acute or chronic exposure. These risks would be even smaller if the sites were paved.","An assessment and quantitative uncertainty analysis of the health risks to workers exposed to chromium contaminated soils Abs: Millions of tons of chromite-ore processing residue have been used as fill in various locations in Northern New Jersey and elsewhere in the United States. The primary toxicants in the residue are trivalent chromium [Cr(III)] and hexavalent chromium [Cr(VI)]. The hazard posed by Cr(III) is negligible due to its low acute and chronic toxicity. In contrast, Cr(VI) is considered a inhalation human carcinogen at high concentrations. Approximately 40 commercial and industrial properties in Northern New Jersey have been identified as containing chromite ore processing residue in the soil. One site, a partially-paved trucking terminal, was evaluated in this assessment. The arithmetic mean and geometric mean concentrations of total chromium in soil were 977 and 359 mg/kg, respectively. The data were log-normal distributed. The arithmetic mean and geometric mean concentrations of Cr(VI) in surface soil were 37.6 and 3.1 mg/kg, respectively. The data could not be fit to a standard distribution, likely due to the large number of samples with concentrations below the method detection limit (65%). Dose was calculated for each exposure route using a Monte Carlo statistical simulation. Probability distributions of most exposure parameters were incorporated into the analyses to predict the range and probability of uptake for persons in the exposed population. The exposure parameter distributions included in this assessment are: the concentrations of Cr(VI) and total chromium in air and soil, fraction of the year when suspension of airborne soil particulates is likely to occur due to weather conditions, fraction of Cr(VI) in air which is respirable (less than 10 microns), soil loading rate on skin, occupational tenure, and body weight. The techniques used in this assessment are applicable for evaluating the human health risks posed by most industrial sites having contaminated soil. The estimated average daily dose (ADD) via ingestion and dermal absorption for the individual exposed at the 95th percentile was about 48,000- and 91-fold below the U.S. EPA reference dose (RfD) for Cr(III) and Cr(VI), respectively. Since inhalation of Cr(VI) contaminated dust (but not ingestion or dermal contact) poses a cancer hazard, the lifetime average daily doses (LADDs) associated with exposure at the 50th and 95th percentile were calculated to be 9.8 x 10(-8) and 1.3 x 10(-6), respectively. Based on this analysis, industrial sites having soil concentrations of Cr(VI) below 230 ppm do not pose a significant noncarcinogenic or carcinogenic health hazard following acute or chronic exposure. These risks would be even smaller if the sites were paved."
1233888,Murthy et al. 1991,Ultrastructural observations in testicular tissue of chromium-treated rats,"The administration of hexavalent chromium (2 mg/kg, ip as potassium dichromate) in adult rats daily for 15 days produced significant increases in the blood and testicular chromium levels. Although no light microscopic pathologic changes or alterations in epididymal sperm counts and motility were observed, lanthanum perfusion in treated rats revealed leakage of Sertoli-cell tight junctions under EM. A few tubules showed marked ultracellular alterations in the form of vacuolization of cytoplasm and degeneration of mitochondria in the epithelial cells. Late stage spermatids were the most affected germ cells. The mitochondrial sheath of the midpiece was vacuolated, incomplete, swollen, or broken in places. The observed alterations may result in the disruption of normal testicular physiology leading to reproductive impairment after chromium exposure.","Ultrastructural observations in testicular tissue of chromium-treated rats Abs: The administration of hexavalent chromium (2 mg/kg, ip as potassium dichromate) in adult rats daily for 15 days produced significant increases in the blood and testicular chromium levels. Although no light microscopic pathologic changes or alterations in epididymal sperm counts and motility were observed, lanthanum perfusion in treated rats revealed leakage of Sertoli-cell tight junctions under EM. A few tubules showed marked ultracellular alterations in the form of vacuolization of cytoplasm and degeneration of mitochondria in the epithelial cells. Late stage spermatids were the most affected germ cells. The mitochondrial sheath of the midpiece was vacuolated, incomplete, swollen, or broken in places. The observed alterations may result in the disruption of normal testicular physiology leading to reproductive impairment after chromium exposure."
1233886,Cervantes and  Silver 1992,Plasmid chromate resistance and chromate reduction,"Compounds of hexavalent chromium (chromates and dichromates) are highly toxic. Plasmid genetic determinants for chromate resistance have been described in several bacterial genera, most notably in Pseudomonas. Resistance to chromate is associated with decreased chromate transport by the resistant cells. The genes for a hydrophobic polypeptide, ChrA, were identified in chromate resistance plasmids of Pseudomonas aeruginosa and Alcaligenes eutrophus. ChrA is postulated to be responsible for the outward membrane translocation of chromate anions. Widespread bacterial reduction of hexavalent chromate to the less toxic trivalent chromic ions is also known. Chromate reduction determinants have not, however, been found on bacterial plasmids or transposons. In different bacteria, chromate reduction is either an aerobic or an anaerobic process (but not both) and is carried out either by soluble proteins or by cell membranes. Chromate reduction may also be a mechanism of resistance to chromate, but this has not been unequivocally shown.","Plasmid chromate resistance and chromate reduction Abs: Compounds of hexavalent chromium (chromates and dichromates) are highly toxic. Plasmid genetic determinants for chromate resistance have been described in several bacterial genera, most notably in Pseudomonas. Resistance to chromate is associated with decreased chromate transport by the resistant cells. The genes for a hydrophobic polypeptide, ChrA, were identified in chromate resistance plasmids of Pseudomonas aeruginosa and Alcaligenes eutrophus. ChrA is postulated to be responsible for the outward membrane translocation of chromate anions. Widespread bacterial reduction of hexavalent chromate to the less toxic trivalent chromic ions is also known. Chromate reduction determinants have not, however, been found on bacterial plasmids or transposons. In different bacteria, chromate reduction is either an aerobic or an anaerobic process (but not both) and is carried out either by soluble proteins or by cell membranes. Chromate reduction may also be a mechanism of resistance to chromate, but this has not been unequivocally shown."
1233885,Heikkilä and  Kauppinen 1992,Occupational exposure to carcinogens in Finland,"Finland has kept a registry on the manufacture and use of carcinogenic agents involving occupational exposure since 1979. Employers must report annually to the labor safety authorities the employees who have been exposed to carcinogens and provide information on carcinogenic agents produced, used, or formed. Out of 131 substances or groups of agents listed as carcinogenic, occupational exposure to 78 of them was reported in 1987. About half of the agents reported were used or produced in industry and half were handled on a laboratory scale. About 15,000 employees from 1,700 work departments were reported to the registry; 17% of them were women. The number of workers reported in 1987 accounted for 0.6% of the total work force. It has been estimated that at least 60,000 workers are exposed annually to carcinogens in Finland. The three most prevalent exposures--hexavalent chromium compounds, nickel and its inorganic compounds, and asbestos--accounted for over 60% of all exposed workers; only five carcinogenic chemicals were produced in Finland in 1987.","Occupational exposure to carcinogens in Finland Abs: Finland has kept a registry on the manufacture and use of carcinogenic agents involving occupational exposure since 1979. Employers must report annually to the labor safety authorities the employees who have been exposed to carcinogens and provide information on carcinogenic agents produced, used, or formed. Out of 131 substances or groups of agents listed as carcinogenic, occupational exposure to 78 of them was reported in 1987. About half of the agents reported were used or produced in industry and half were handled on a laboratory scale. About 15,000 employees from 1,700 work departments were reported to the registry; 17% of them were women. The number of workers reported in 1987 accounted for 0.6% of the total work force. It has been estimated that at least 60,000 workers are exposed annually to carcinogens in Finland. The three most prevalent exposures--hexavalent chromium compounds, nickel and its inorganic compounds, and asbestos--accounted for over 60% of all exposed workers; only five carcinogenic chemicals were produced in Finland in 1987."
1233884,Gao et al. 1992,Induction of DNA strand breaks in peripheral lymphocytes by soluble chromium compounds,"1. Incubation of human lymphocytes with sodium dichromate (CrVI) at 37 degrees C for 3 h resulted in a dose-dependent increase in DNA strand breaks without concurrent cytotoxicity. In contrast, chromium acetate hydroxide (CrIII) failed to induce DNA strand breaks at sub-cytotoxic concentrations. 2. DNA strand breaks were also detected in the peripheral lymphocytes of Wistar rats, 24 h after intratracheal instillation of sodium dichromate (1.3 and 2.5 mg kg-1). Instillation of chromium acetate hydroxide (up to 21.8 mg kg-1) failed to induce DNA strand breaks in peripheral lymphocytes. In accord with previous studies, hexavalent chromium was found to be more readily absorbed from the lungs into the peripheral blood than chromium in its trivalent form. 3. The results of this study indicate that fluorometric analysis of DNA unwinding (FADU) in peripheral lymphocytes might be a convenient method of measuring an important biological effect of chromium in occupationally-exposed workers.","Induction of DNA strand breaks in peripheral lymphocytes by soluble chromium compounds Abs: 1. Incubation of human lymphocytes with sodium dichromate (CrVI) at 37 degrees C for 3 h resulted in a dose-dependent increase in DNA strand breaks without concurrent cytotoxicity. In contrast, chromium acetate hydroxide (CrIII) failed to induce DNA strand breaks at sub-cytotoxic concentrations. 2. DNA strand breaks were also detected in the peripheral lymphocytes of Wistar rats, 24 h after intratracheal instillation of sodium dichromate (1.3 and 2.5 mg kg-1). Instillation of chromium acetate hydroxide (up to 21.8 mg kg-1) failed to induce DNA strand breaks in peripheral lymphocytes. In accord with previous studies, hexavalent chromium was found to be more readily absorbed from the lungs into the peripheral blood than chromium in its trivalent form. 3. The results of this study indicate that fluorometric analysis of DNA unwinding (FADU) in peripheral lymphocytes might be a convenient method of measuring an important biological effect of chromium in occupationally-exposed workers."
1233883,Christensen et al. 1992,Cytotoxic effects of hexavalent chromium in cultured murine macrophages,"The in vitro effect of hexavalent chromium (CrVI) on mouse peritoneal macrophages was investigated. Our results demonstrate the existence of a threshold concentration of 2.5 microM of CrVI above which chromium affects the viability of macrophages in a concentration dependent manner. Morphological changes were seen with increasing concentrations of chromium. Evidence is presented that protein production (virus-induced interferon) in murine peritoneal macrophages was impaired by hexavalent chromium at low concentrations, while random migration and phagocytic activity were only affected at high concentrations of CrVI.","Cytotoxic effects of hexavalent chromium in cultured murine macrophages Abs: The in vitro effect of hexavalent chromium (CrVI) on mouse peritoneal macrophages was investigated. Our results demonstrate the existence of a threshold concentration of 2.5 microM of CrVI above which chromium affects the viability of macrophages in a concentration dependent manner. Morphological changes were seen with increasing concentrations of chromium. Evidence is presented that protein production (virus-induced interferon) in murine peritoneal macrophages was impaired by hexavalent chromium at low concentrations, while random migration and phagocytic activity were only affected at high concentrations of CrVI."
1233881,Sitjes et al. 1992,Induction of ribonucleoside diphosphate reductase gene transcription by chemicals in Escherichia coli,"A fusion between the promoter of the nrdA gene of Escherichia coli and the lacZ gene has been constructed, and the induction of nrdA gene expression by 20 organic and 20 inorganic chemicals has been studied. The inducing compounds of the SOS genes, such as bleomycin, captan, ciprofloxacin, enoxacin, hydroxyurea, N-methyl-N'-nitro-N-nitrosoguanidine, mitomycin C, nalidixic acid, ofloxacin and hexavalent chromium compounds also trigger the expression of the nrdA gene. Other chemicals such as aluminium, manganese and zinc salts, reported as negative in the SOS Chromotest, are also inducers of the nrdA gene. These results suggest that ribonucleoside diphosphate reductase transcription is increased by chemicals able to either block DNA synthesis or to alter the enzymes participating in the DNA replication. Induction of nrdA gene is an effect to be further considered in the study of alterations produced by physical or chemical treatments which act upon DNA metabolism.","Induction of ribonucleoside diphosphate reductase gene transcription by chemicals in Escherichia coli Abs: A fusion between the promoter of the nrdA gene of Escherichia coli and the lacZ gene has been constructed, and the induction of nrdA gene expression by 20 organic and 20 inorganic chemicals has been studied. The inducing compounds of the SOS genes, such as bleomycin, captan, ciprofloxacin, enoxacin, hydroxyurea, N-methyl-N'-nitro-N-nitrosoguanidine, mitomycin C, nalidixic acid, ofloxacin and hexavalent chromium compounds also trigger the expression of the nrdA gene. Other chemicals such as aluminium, manganese and zinc salts, reported as negative in the SOS Chromotest, are also inducers of the nrdA gene. These results suggest that ribonucleoside diphosphate reductase transcription is increased by chemicals able to either block DNA synthesis or to alter the enzymes participating in the DNA replication. Induction of nrdA gene is an effect to be further considered in the study of alterations produced by physical or chemical treatments which act upon DNA metabolism."
1233880,Wepener et al. 1992,The effect of hexavalent chromium at different pH values on the haematology of Tilapia sparrmanii (Cichlidae),1. The haematology of Tilapia sparrmanii (Smith) was investigated after exposure to 0.098 mg.l-1 hexavalent chromium at three different pH values. 2. Statistically significant changes occurred between the values of parameters of experimental and control fish. 3. At lower pH values erythrocytosis and leucocytosis were evident. 4. At an alkaline (9) pH anaemic and leucopenic conditions were observed. 5. T. sparrmanii adapted to chronic exposure to hexavalent chromium.,The effect of hexavalent chromium at different pH values on the haematology of Tilapia sparrmanii (Cichlidae) Abs: 1. The haematology of Tilapia sparrmanii (Smith) was investigated after exposure to 0.098 mg.l-1 hexavalent chromium at three different pH values. 2. Statistically significant changes occurred between the values of parameters of experimental and control fish. 3. At lower pH values erythrocytosis and leucocytosis were evident. 4. At an alkaline (9) pH anaemic and leucopenic conditions were observed. 5. T. sparrmanii adapted to chronic exposure to hexavalent chromium.
1233879,Bukowski et al. 1992,"Chromium exposure assessment of outdoor workers in Hudson County, NJ","A large quantity of chromate chemical production waste, containing hexavalent chromium, has been used as fill at over 150 sites in Hudson County, New Jersey. One site is in a state park, and several other sites are adjacent to the park. Blood and urinary chromium levels were compared between 17 employees at the Hudson County park and 35 employees from two other state parks. A limited number of soil and personal air samples were also taken. Urinary and RBC chromium levels between the two groups were similar, even after adjusting for potentially confounding variables. The air sampling results demonstrated slightly higher chromium levels at Hudson County, but these were still very low level in nature (mean = 0.18 micrograms/m3). These results call into question the utility of chromium biomonitoring under environmental exposure conditions.","Chromium exposure assessment of outdoor workers in Hudson County, NJ Abs: A large quantity of chromate chemical production waste, containing hexavalent chromium, has been used as fill at over 150 sites in Hudson County, New Jersey. One site is in a state park, and several other sites are adjacent to the park. Blood and urinary chromium levels were compared between 17 employees at the Hudson County park and 35 employees from two other state parks. A limited number of soil and personal air samples were also taken. Urinary and RBC chromium levels between the two groups were similar, even after adjusting for potentially confounding variables. The air sampling results demonstrated slightly higher chromium levels at Hudson County, but these were still very low level in nature (mean = 0.18 micrograms/m3). These results call into question the utility of chromium biomonitoring under environmental exposure conditions."
1233878,Paustenbach et al. 1992,"Review of the allergic contact dermatitis hazard posed by chromium-contaminated soil: identifying a ""safe"" concentration","At least 200 sites in the United States contain soil with elevated levels of trivalent and hexavalent chromium [Cr(III) and Cr(VI)]. Although the potential cancer hazard posed by airborne Cr(VI) has been the primary concern for these sites, a soil cleanup standard based on the potential elicitation of allergic contact dermatitis has been proposed for sites in Hudson County, N.J. This paper describes the rationale for identifying a soil concentration of Cr(VI) that should not pose an allergic contact dermatitis hazard-even in sensitized persons. A literature review of eight published patch test studies that evaluated the allergic response to potassium dichromate was conducted. These studies were evaluated for clinical and statistical relevance in establishing a threshold dose of Cr(VI) to which no more than 10% of the subpopulation sensitized to chromium would respond, and that would protect at least 99.84% of the general population. Although each of the studies had certain methodological limitations when evaluated against current test methods, the data set proved useful for deriving an estimated threshold. Using computer data-fitting techniques based on truncated lognormal distributions, a weighted mean 10% threshold of approximately 150 ppm potassium dichromate or 54 ppm Cr(VI) was identified for the eight studies. Due to the types of limitations noted for these studies, this threshold is likely to be somewhat conservative. Test results have shown that between 5 and 10% of the Cr(VI) at concentrations less than about 500 ppm are released from a soil matrix into an isotonic saline solution simulating sweat. Using human sweat as the extractant, it has been shown that only 0.1% of the CR(VI) at concentrations of approximately 1,000 ppm are released from a soil matrix into sweat. Based on 10% solubilization of soil-bound Cr(VI) and the results of our statistical analysis of previous threshold studies, a concentration of approximately 350 to 500 ppm Cr(VI) in soil should be sufficiently low to protect virtually all exposed people, including children, from chromium-induced allergic contact dermatitis.","Review of the allergic contact dermatitis hazard posed by chromium-contaminated soil: identifying a ""safe"" concentration Abs: At least 200 sites in the United States contain soil with elevated levels of trivalent and hexavalent chromium [Cr(III) and Cr(VI)]. Although the potential cancer hazard posed by airborne Cr(VI) has been the primary concern for these sites, a soil cleanup standard based on the potential elicitation of allergic contact dermatitis has been proposed for sites in Hudson County, N.J. This paper describes the rationale for identifying a soil concentration of Cr(VI) that should not pose an allergic contact dermatitis hazard-even in sensitized persons. A literature review of eight published patch test studies that evaluated the allergic response to potassium dichromate was conducted. These studies were evaluated for clinical and statistical relevance in establishing a threshold dose of Cr(VI) to which no more than 10% of the subpopulation sensitized to chromium would respond, and that would protect at least 99.84% of the general population. Although each of the studies had certain methodological limitations when evaluated against current test methods, the data set proved useful for deriving an estimated threshold. Using computer data-fitting techniques based on truncated lognormal distributions, a weighted mean 10% threshold of approximately 150 ppm potassium dichromate or 54 ppm Cr(VI) was identified for the eight studies. Due to the types of limitations noted for these studies, this threshold is likely to be somewhat conservative. Test results have shown that between 5 and 10% of the Cr(VI) at concentrations less than about 500 ppm are released from a soil matrix into an isotonic saline solution simulating sweat. Using human sweat as the extractant, it has been shown that only 0.1% of the CR(VI) at concentrations of approximately 1,000 ppm are released from a soil matrix into sweat. Based on 10% solubilization of soil-bound Cr(VI) and the results of our statistical analysis of previous threshold studies, a concentration of approximately 350 to 500 ppm Cr(VI) in soil should be sufficiently low to protect virtually all exposed people, including children, from chromium-induced allergic contact dermatitis."
1233877,Howard et al. 1992,Enhanced production of micronuclei by hexavalent chromium in cultured CHO cells,"Induction of micronuclei by hexavalent chromium (7440473) was studied in Chinese-hamster ovary (CHO) cells. Cultures of exponentially growing CHO cells were incubated with 10(-8), 10(-7), 10(-6), or 10(-5) molar (M) chromic-oxide (1308389) or potassium-dichromate (7778509) for 24 hours at 37 degrees-C. The cells were then scored for micronuclei. Chromic-oxide and potassium-dichromate over the range 10(-8) to 10(-6)M caused dose related increases in micronuclei frequency. Potassium-dichromate was a more potent inducer than chromic-oxide, the 10(-6)M dose causing a 3.2 fold increase in micronucleus frequency relative to the control value versus a 2.8 fold increase caused by chromic-oxide. The 10(-5) dose of either compound was slightly cytotoxic. The authors conclude that chromic-oxide and potassium-dichromate increase the frequency of micronucleated CHO cells. This finding supports the results of other studies that have shown that hexavalent chromium compounds are genotoxic. Possible mechanisms for the genotoxicity of chromium (Cr) ion (Cr+6) compounds were discussed.","Enhanced production of micronuclei by hexavalent chromium in cultured CHO cells Abs: Induction of micronuclei by hexavalent chromium (7440473) was studied in Chinese-hamster ovary (CHO) cells. Cultures of exponentially growing CHO cells were incubated with 10(-8), 10(-7), 10(-6), or 10(-5) molar (M) chromic-oxide (1308389) or potassium-dichromate (7778509) for 24 hours at 37 degrees-C. The cells were then scored for micronuclei. Chromic-oxide and potassium-dichromate over the range 10(-8) to 10(-6)M caused dose related increases in micronuclei frequency. Potassium-dichromate was a more potent inducer than chromic-oxide, the 10(-6)M dose causing a 3.2 fold increase in micronucleus frequency relative to the control value versus a 2.8 fold increase caused by chromic-oxide. The 10(-5) dose of either compound was slightly cytotoxic. The authors conclude that chromic-oxide and potassium-dichromate increase the frequency of micronucleated CHO cells. This finding supports the results of other studies that have shown that hexavalent chromium compounds are genotoxic. Possible mechanisms for the genotoxicity of chromium (Cr) ion (Cr+6) compounds were discussed."
1233876,Vyskocil et al. 1992,Lack of renal changes in stainless steel welders exposed to chromium and nickel,"Biochemical markers of kidney damage were examined in 52 male stainless steel welders (manual metal arc welding) exposed to chromium and nickel. No difference was found in the mean urinary excretion of total proteins, albumin, protein 1, transferrin, retinol-binding protein, lactate dehydrogenase, lysozyme, or beta-N-acetylglucosaminidase in a comparison with matched referents. Beta 2-microglobulin was slightly increased in those welders with a urinary chromium concentration of greater than 64.5 nmol.mmol-1 creatinine. The prevalences of abnormal values did not differ from those observed in the reference group. No correlation was found between the concentrations of chromium or nickel in urine and that of proteins or enzymes. No consistent or clinically significant renal impairment was revealed among the stainless steel welders exposed to a chromium air concentration slightly above the current threshold limit value of the American Conference of Governmental Industrial Hygienists for water-soluble hexavalent chromium compounds (50 micrograms.m-3).","Lack of renal changes in stainless steel welders exposed to chromium and nickel Abs: Biochemical markers of kidney damage were examined in 52 male stainless steel welders (manual metal arc welding) exposed to chromium and nickel. No difference was found in the mean urinary excretion of total proteins, albumin, protein 1, transferrin, retinol-binding protein, lactate dehydrogenase, lysozyme, or beta-N-acetylglucosaminidase in a comparison with matched referents. Beta 2-microglobulin was slightly increased in those welders with a urinary chromium concentration of greater than 64.5 nmol.mmol-1 creatinine. The prevalences of abnormal values did not differ from those observed in the reference group. No correlation was found between the concentrations of chromium or nickel in urine and that of proteins or enzymes. No consistent or clinically significant renal impairment was revealed among the stainless steel welders exposed to a chromium air concentration slightly above the current threshold limit value of the American Conference of Governmental Industrial Hygienists for water-soluble hexavalent chromium compounds (50 micrograms.m-3)."
1233875,Ptashekas 1992,Environmental monitoring in Lithuania. Environmental distress signals: gastrointestinal epithelial barrier after exposure to chemical agents,"Lithuania's environment is heavily polluted as a result of domestic and transboundary contamination. The main ecological problems are related to atmospheric pollution; water contamination; soil, water, and forest acidification; nitrogen-compounds overload of soil, water, and food; and contamination with agricultural chemicals and heavy metals. The increased environmental distress is a menace to public health in Lithuania. Experimental studies need to be designed and used to ascertain the effects of environmental distress on the gastrointestinal tract epithelial barrier. Our electronmicroscopic and immunohistochemical study of human gastrointestinal endocrine cells revealed changes in the amount of secretory material and intracytoplasmic vacuolization after exposure to the environmental chemicals such as hexavalent chromium and the herbicide Saprol. The most affected were the EC (serotonin, motilin, substance P), D (somatostatin), A (glucagon), B (insulin), and mast (histamine, serotonin, heparin) cells. These results provide ultrastructural evidence of digestive tract epithelial barrier reaction as an expression of environmental distress signals of the organism.","Environmental monitoring in Lithuania. Environmental distress signals: gastrointestinal epithelial barrier after exposure to chemical agents Abs: Lithuania's environment is heavily polluted as a result of domestic and transboundary contamination. The main ecological problems are related to atmospheric pollution; water contamination; soil, water, and forest acidification; nitrogen-compounds overload of soil, water, and food; and contamination with agricultural chemicals and heavy metals. The increased environmental distress is a menace to public health in Lithuania. Experimental studies need to be designed and used to ascertain the effects of environmental distress on the gastrointestinal tract epithelial barrier. Our electronmicroscopic and immunohistochemical study of human gastrointestinal endocrine cells revealed changes in the amount of secretory material and intracytoplasmic vacuolization after exposure to the environmental chemicals such as hexavalent chromium and the herbicide Saprol. The most affected were the EC (serotonin, motilin, substance P), D (somatostatin), A (glucagon), B (insulin), and mast (histamine, serotonin, heparin) cells. These results provide ultrastructural evidence of digestive tract epithelial barrier reaction as an expression of environmental distress signals of the organism."
1233874,Manning et al. 1992,Transcriptional inhibition by carcinogenic chromate: Relationship to DNA damage,"Hexavalent chromium compounds are carcinogenic to humans, are potent inducers of tumors in experimental animals, and can neoplastically transform cells in culture. In this study, the effects of sodium chromate on the expression of the 78-kDa glucose-regulated protein (GRP78) gene and on general transcription were investigated with respect to the DNA damage induced by this agent. DNA single-strand breaks, DNA-protein cross-links, and chromium-DNA adducts were present in CHO cells immediately after 2 h of treatment with sodium chromate. Subsequently, these types of damage were repaired at different rates. Single-strand breaks were essentially repaired after 8 h. By 24 h posttreatment, no cross-links remained in cells exposed to 30 or 150 microM chromate, although cells treated with the 300-microM concentration still contained cross-links at that time. DNA-chromium adducts remained unrepaired for at least 32 h. The moderate constitutive level of GRP78 mRNA was not affected by chromate. Chromate did, however, suppress induction of this gene by tunicamycin in a concentration-and time-dependent manner. Thirty micromolar sodium chromate (96% survival), which caused the least DNA damage, had no effect on GRP78 induction, general RNA synthesis, or mRNA synthesis. Induction of GRP78 was suppressed immediately and 12 h after treatment with 150 microM chromate (54% survival), although there was a partial recovery of induction at 24 h after treatment, which correlated with the repair of DNA-protein cross-links. In contrast, both total cytoplasmic RNA and mRNA synthesis were suppressed by approximately 60-75% for at least 32 h by 150 microM chromate. At the 300-microM concentration (8% survival), where DNA-protein cross-links persisted beyond 24 h, GRP78 induction was totally suppressed for at least 24 h, while total RNA and mRNA synthesis were suppressed by 80-90% for at least 32 h. Overall, the effects of chromate on GRP78 induction correlated most closely with the presence of DNA-protein cross-links, but suppression of total RNA and mRNA synthesis correlated with the presence of DNA-chromium adducts. These results indicate that chromate exerts differential effects on the induction of the GRP78 gene and on general transcription.","Transcriptional inhibition by carcinogenic chromate: Relationship to DNA damage Abs: Hexavalent chromium compounds are carcinogenic to humans, are potent inducers of tumors in experimental animals, and can neoplastically transform cells in culture. In this study, the effects of sodium chromate on the expression of the 78-kDa glucose-regulated protein (GRP78) gene and on general transcription were investigated with respect to the DNA damage induced by this agent. DNA single-strand breaks, DNA-protein cross-links, and chromium-DNA adducts were present in CHO cells immediately after 2 h of treatment with sodium chromate. Subsequently, these types of damage were repaired at different rates. Single-strand breaks were essentially repaired after 8 h. By 24 h posttreatment, no cross-links remained in cells exposed to 30 or 150 microM chromate, although cells treated with the 300-microM concentration still contained cross-links at that time. DNA-chromium adducts remained unrepaired for at least 32 h. The moderate constitutive level of GRP78 mRNA was not affected by chromate. Chromate did, however, suppress induction of this gene by tunicamycin in a concentration-and time-dependent manner. Thirty micromolar sodium chromate (96% survival), which caused the least DNA damage, had no effect on GRP78 induction, general RNA synthesis, or mRNA synthesis. Induction of GRP78 was suppressed immediately and 12 h after treatment with 150 microM chromate (54% survival), although there was a partial recovery of induction at 24 h after treatment, which correlated with the repair of DNA-protein cross-links. In contrast, both total cytoplasmic RNA and mRNA synthesis were suppressed by approximately 60-75% for at least 32 h by 150 microM chromate. At the 300-microM concentration (8% survival), where DNA-protein cross-links persisted beyond 24 h, GRP78 induction was totally suppressed for at least 24 h, while total RNA and mRNA synthesis were suppressed by 80-90% for at least 32 h. Overall, the effects of chromate on GRP78 induction correlated most closely with the presence of DNA-protein cross-links, but suppression of total RNA and mRNA synthesis correlated with the presence of DNA-chromium adducts. These results indicate that chromate exerts differential effects on the induction of the GRP78 gene and on general transcription."
1233873,Venugopal and  Reddy 1992,Nephrotoxic and hepatotoxic effects of trivalent and hexavalent chromium in a teleost fish Anabas scandens: enzymological and biochemical changes,"The effects of trivalent and hexavalent chromium (Cr3+ and Cr6+) compounds on renal and hepatic respiratory enzymes and metabolites of a freshwater fish, Anabas scandens, were studied. In a subchronic exposure of 30 days, both forms of chromium inhibited the activities of lactate dehydrogenase, succinate dehydrogenase, malate dehydrogenase, and isocitrate dehydrogenase, whereas the hexavalent form induced greater effects. The levels of pyruvate and lactate are not exactly reflected in lactate dehydrogenase activity.","Nephrotoxic and hepatotoxic effects of trivalent and hexavalent chromium in a teleost fish Anabas scandens: enzymological and biochemical changes Abs: The effects of trivalent and hexavalent chromium (Cr3+ and Cr6+) compounds on renal and hepatic respiratory enzymes and metabolites of a freshwater fish, Anabas scandens, were studied. In a subchronic exposure of 30 days, both forms of chromium inhibited the activities of lactate dehydrogenase, succinate dehydrogenase, malate dehydrogenase, and isocitrate dehydrogenase, whereas the hexavalent form induced greater effects. The levels of pyruvate and lactate are not exactly reflected in lactate dehydrogenase activity."
1233872,Ueno 1992,Protective effects of thiol containing chelating agents against liver injury induced by hexavalent chromium in mice,"The effects of the chelating agents, L-cysteine ethyl ester (LCEE), L-cysteine methyl ester (LCME), N-acetyl-L-(+)-cysteine (NAC), 2,3-dimercapto-1-propanesulfonic acid (DMPS), N-(2-mercaptopropionyl)-glycine (MPG), and 2,3-dimercaptosuccinic acid (DMSA), on the distribution, excretion and hepatotoxicity of ip injected hexavalent chromium were studied in male mice. The chelating agents (500 mg/kg) were injected iv as single doses given immediately or 30 min after potassium dichromate (20 mg Cr/kg) as hexavalent chromium was administered. When the chelating agents were injected immediately after the metal compound was administered, LCEE, LCME, NAC, DMPS, and MPG reduced the chromium contents in the liver and kidney, and facilitated the urinary excretion of chromium. The liver injury induced by chromium, which was evaluated by serum ornithine carbamyl transferase (OCT) activity, was prevented significantly by LCEE, LCME, DMPS, and MPG. On the other hand, when these chelating agents were injected at 30 min after the chromium administration, only DMSA could prevent the liver injury induced by the metal, and decreased the chromium contents in the liver. However, when DMSA was given at 3 hr after the metal administration, there was no therapeutic effect on them. These results suggest that the chelating agents tested may be useful in the treatment of intoxications due to hexavalent chromium, but there is the difference in the therapeutic effects of the chelating agents owing to the time intervals after the administration of the metal.","Protective effects of thiol containing chelating agents against liver injury induced by hexavalent chromium in mice Abs: The effects of the chelating agents, L-cysteine ethyl ester (LCEE), L-cysteine methyl ester (LCME), N-acetyl-L-(+)-cysteine (NAC), 2,3-dimercapto-1-propanesulfonic acid (DMPS), N-(2-mercaptopropionyl)-glycine (MPG), and 2,3-dimercaptosuccinic acid (DMSA), on the distribution, excretion and hepatotoxicity of ip injected hexavalent chromium were studied in male mice. The chelating agents (500 mg/kg) were injected iv as single doses given immediately or 30 min after potassium dichromate (20 mg Cr/kg) as hexavalent chromium was administered. When the chelating agents were injected immediately after the metal compound was administered, LCEE, LCME, NAC, DMPS, and MPG reduced the chromium contents in the liver and kidney, and facilitated the urinary excretion of chromium. The liver injury induced by chromium, which was evaluated by serum ornithine carbamyl transferase (OCT) activity, was prevented significantly by LCEE, LCME, DMPS, and MPG. On the other hand, when these chelating agents were injected at 30 min after the chromium administration, only DMSA could prevent the liver injury induced by the metal, and decreased the chromium contents in the liver. However, when DMSA was given at 3 hr after the metal administration, there was no therapeutic effect on them. These results suggest that the chelating agents tested may be useful in the treatment of intoxications due to hexavalent chromium, but there is the difference in the therapeutic effects of the chelating agents owing to the time intervals after the administration of the metal."
1233871,Gendusa et al. 1993,Toxicity of hexavalent chromium from aqueous and sediment sources to Pimephales promelas and Ictalurus punctatus,,Toxicity of hexavalent chromium from aqueous and sediment sources to Pimephales promelas and Ictalurus punctatus Abs: 
1233870,Gao et al. 1993,Hexavalent chromium produces DNA strand breakage but not unscheduled DNA synthesis at sub-cytotoxic concentrations in hepatocytes,"Rat hepatocytes were used to investigate the possible induction of unscheduled DNA synthesis (UDS) and the extent of DNA strand breaks induced by sodium dichromate (a representative chromium(VI) compound) and chromium acetate hydroxide (chromium(III)) in vitro. Cytotoxicity, measured using tetrazolium salt (MTT) reduction assay, was found at a much higher dose of chromium(III), (> 50 microM), compared to that of chromium(VI), (> 2.5 microM), in cultured hepatocytes over 20 h treatment at 37 degrees C. Chromium(VI), but not chromium(III), stimulated minimal UDS in hepatocytes at sub-cytotoxic concentrations. A positive UDS response was only observed at cytotoxic concentration. DNA strand breaks in hepatocytes were induced by chromium(VI) following incubation at 37 degrees C for 1 h at doses of 10, 20 and 40 microM sodium dichromate. The subsequent ligation of such strand breaks in hepatocytes treated with 40 microM chromium(VI) for 1 h at 37 degrees C was demonstrated. The majority of strand breaks was repaired within 30 min following removal of the chromate. In conclusion, chromate-induced DNA strand breakage, possibly involving the formation of oxygen radicals and lack of significant UDS have some analogy to those produced by ionizing radiation.","Hexavalent chromium produces DNA strand breakage but not unscheduled DNA synthesis at sub-cytotoxic concentrations in hepatocytes Abs: Rat hepatocytes were used to investigate the possible induction of unscheduled DNA synthesis (UDS) and the extent of DNA strand breaks induced by sodium dichromate (a representative chromium(VI) compound) and chromium acetate hydroxide (chromium(III)) in vitro. Cytotoxicity, measured using tetrazolium salt (MTT) reduction assay, was found at a much higher dose of chromium(III), (> 50 microM), compared to that of chromium(VI), (> 2.5 microM), in cultured hepatocytes over 20 h treatment at 37 degrees C. Chromium(VI), but not chromium(III), stimulated minimal UDS in hepatocytes at sub-cytotoxic concentrations. A positive UDS response was only observed at cytotoxic concentration. DNA strand breaks in hepatocytes were induced by chromium(VI) following incubation at 37 degrees C for 1 h at doses of 10, 20 and 40 microM sodium dichromate. The subsequent ligation of such strand breaks in hepatocytes treated with 40 microM chromium(VI) for 1 h at 37 degrees C was demonstrated. The majority of strand breaks was repaired within 30 min following removal of the chromate. In conclusion, chromate-induced DNA strand breakage, possibly involving the formation of oxygen radicals and lack of significant UDS have some analogy to those produced by ionizing radiation."
1233865,Langård 1993,Role of chemical species and exposure characteristics in cancer among persons occupationally exposed to chromium compounds,"Epidemiologic studies on chromate workers are considered with special reference to the valency of chromium compounds, carcinogenic potency, and water solubility. It is assumed that all hexavalent chromium compounds are carcinogenic to humans when inhaled but that there is no evidence that trivalent compounds are carcinogenic. It is suggested that zinc chromate is a highly potent carcinogen and also that calcium chromate may be carcinogenic. There are indications that chromates of low water solubility may be less potent carcinogens than compounds of greater solubility. Evidence is also presented for possible interactions with smoking and other factors involved in work-related cancers.","Role of chemical species and exposure characteristics in cancer among persons occupationally exposed to chromium compounds Abs: Epidemiologic studies on chromate workers are considered with special reference to the valency of chromium compounds, carcinogenic potency, and water solubility. It is assumed that all hexavalent chromium compounds are carcinogenic to humans when inhaled but that there is no evidence that trivalent compounds are carcinogenic. It is suggested that zinc chromate is a highly potent carcinogen and also that calcium chromate may be carcinogenic. There are indications that chromates of low water solubility may be less potent carcinogens than compounds of greater solubility. Evidence is also presented for possible interactions with smoking and other factors involved in work-related cancers."
1233864,Yamamoto et al. 1993,Kinetics and modeling of hexavalent chromium reduction in Enterobacter cloacae,"Kinetics of bacterial reduction of toxic hexavalent chromium (chromate: CrO(4) (2-)) was investigated using batch and fedbatch cultures of Enterobacter cloacae strain HO1. In fedbatch cultures, the CrO(4) (2-) feed was controlled on the basis of the rate of pH change. This control strategy has proven to be useful for avoiding toxic CrO(4) (2-) overload. A simple mathematical model was developed to describe the bacterial process of CrO(4) (2-) reduction. In this model, two types of bacterial cells were considered: induced, CrO(4) (2-)-resistant cells and uninduced, sensitive ones. Only resistant cells were assumed to be able to reduce CrO(4) (2-). These fundamental ideas were supported by the model predictions which well approximated all experimental data. In a simulation study, the model was also used to optimize fed-batch cultures, instead of lengthy and expensive laboratory experiments.","Kinetics and modeling of hexavalent chromium reduction in Enterobacter cloacae Abs: Kinetics of bacterial reduction of toxic hexavalent chromium (chromate: CrO(4) (2-)) was investigated using batch and fedbatch cultures of Enterobacter cloacae strain HO1. In fedbatch cultures, the CrO(4) (2-) feed was controlled on the basis of the rate of pH change. This control strategy has proven to be useful for avoiding toxic CrO(4) (2-) overload. A simple mathematical model was developed to describe the bacterial process of CrO(4) (2-) reduction. In this model, two types of bacterial cells were considered: induced, CrO(4) (2-)-resistant cells and uninduced, sensitive ones. Only resistant cells were assumed to be able to reduce CrO(4) (2-). These fundamental ideas were supported by the model predictions which well approximated all experimental data. In a simulation study, the model was also used to optimize fed-batch cultures, instead of lengthy and expensive laboratory experiments."
1233863,Bonde 1993,"The risk of male subfecundity attributable to welding of metals. Studies of semen quality, infertility, fertility, adverse pregnancy outcome and childhood malignancy","These studies were initiated by the results of two Danish investigations of infertility clients, which indicated the reduced fecundity of male metal welders. The objective was to refute or corroborate the effects of welding on male reproductive capability and--if there was any effect--to identify the causal exposures. The initial hypothesis postulated reduced spermatogenesis, spontaneous abortion, congenital malformation and childhood malignancy following exposure to hexavalent chromium among stainless steel welders. Subsequently, a hypothesis concerned with the significance of exposure to radiant heat on reduced semen quality was put forward. These studies comprised a case-referent study of infertility, cross-sectional and longitudinal studies of semen quality and historical cohort studies of fertility, pregnancy outcome and cancer in offspring. Exposure to welding was reported with a higher frequency during periods of infertility than prior to conception in the case-referent study (OR 2.0, 95% CI 1.0-4.0). This finding is consistent with the main cross-sectional study showing reduced semen quality in welders [average reduction ranging from 8% (sperm penetration rate in eggwhite) to 28% (total sperm count)] and with the cohort study revealing reduced fertility in relation to welding (OR 0.89, 95% CI 0.83-0.97). However, reduced semen quality and fertility were not attributable to the welding of stainless steel but to the welding of mild steel; and no relationship was found between biological measures of exposure to chromium and parameters of semen quality. If the unexpected association between mild steel welding and reduced fecundity is causal, the biological mechanisms involved are obscure. A separate longitudinal study leaves little doubt that moderate radiant heat exposure may cause reversible deterioration of semen quality, but it is not justified to generalize this observation to the entire population of welders. Male-mediated effects on occurrence of congenital malformation and cancer in offspring from stainless steel welding are not indicated by the studies. Weak indications of an increased risk of spontaneous abortion among partners to stainless steel welders (OR 1.9, 95% CI 1.1-3.2) need to be refuted or corroborated in future studies. Suggested effects of mild steel welding on male fecundity should be corroborated by longitudinal controlled studies of semen quality examined before and during exposure and by prospective studies of fecundability in couples trying to conceive a child. On account of the present knowledge it is not possible to recommend rational preventative measures with the exception of elimination of radiant heat exposure in cases of infertility.(ABSTRACT TRUNCATED AT 400 WORDS)","The risk of male subfecundity attributable to welding of metals. Studies of semen quality, infertility, fertility, adverse pregnancy outcome and childhood malignancy Abs: These studies were initiated by the results of two Danish investigations of infertility clients, which indicated the reduced fecundity of male metal welders. The objective was to refute or corroborate the effects of welding on male reproductive capability and--if there was any effect--to identify the causal exposures. The initial hypothesis postulated reduced spermatogenesis, spontaneous abortion, congenital malformation and childhood malignancy following exposure to hexavalent chromium among stainless steel welders. Subsequently, a hypothesis concerned with the significance of exposure to radiant heat on reduced semen quality was put forward. These studies comprised a case-referent study of infertility, cross-sectional and longitudinal studies of semen quality and historical cohort studies of fertility, pregnancy outcome and cancer in offspring. Exposure to welding was reported with a higher frequency during periods of infertility than prior to conception in the case-referent study (OR 2.0, 95% CI 1.0-4.0). This finding is consistent with the main cross-sectional study showing reduced semen quality in welders [average reduction ranging from 8% (sperm penetration rate in eggwhite) to 28% (total sperm count)] and with the cohort study revealing reduced fertility in relation to welding (OR 0.89, 95% CI 0.83-0.97). However, reduced semen quality and fertility were not attributable to the welding of stainless steel but to the welding of mild steel; and no relationship was found between biological measures of exposure to chromium and parameters of semen quality. If the unexpected association between mild steel welding and reduced fecundity is causal, the biological mechanisms involved are obscure. A separate longitudinal study leaves little doubt that moderate radiant heat exposure may cause reversible deterioration of semen quality, but it is not justified to generalize this observation to the entire population of welders. Male-mediated effects on occurrence of congenital malformation and cancer in offspring from stainless steel welding are not indicated by the studies. Weak indications of an increased risk of spontaneous abortion among partners to stainless steel welders (OR 1.9, 95% CI 1.1-3.2) need to be refuted or corroborated in future studies. Suggested effects of mild steel welding on male fecundity should be corroborated by longitudinal controlled studies of semen quality examined before and during exposure and by prospective studies of fecundability in couples trying to conceive a child. On account of the present knowledge it is not possible to recommend rational preventative measures with the exception of elimination of radiant heat exposure in cases of infertility.(ABSTRACT TRUNCATED AT 400 WORDS)"
1233861,Blankenship et al. 1994,Apoptosis is the mode of cell death caused by carcinogenic chromium,"The role of apoptosis in the mechanism of toxicity of hexavalent chromium, a human carcinogen, was investigated. Chinese hamster ovary (CHO) cells were treated with 150 or 300 microM sodium chromate for 2 hr, doses which decreased colony-forming efficiency to 53 and 5% of control, respectively. Cell growth was inhibited at least up to Day 8 after treatment. DNA synthesis was inhibited to 30 and 19% of control at 1 hr after treatment, and did not begin to recover until Day 4 after treatment. Protein synthesis was inhibited by 52 and 60% in 150 and 300 microM treated cells, respectively, 1 h after treatment, and recovered to 142 and 93%, respectively, at 24 hr. Incubation of cells with nontoxic doses of cycloheximide for 24 hr after treatment produced synergistic toxicity with chromate in colony-forming efficiency assays. Ion gradients persisted to Day 2 as revealed by exclusion of trypan blue dye in 97% of treated cells. Fluorescence microscopy of acridine orange-stained cells revealed morphological features of apoptosis including nuclear fragmentation in more than 90% of detached nonadherent cells and up to 22% of adherent cells by Day 2 after treatment. Untreated cells remained morphologically normal. Transmission electron microscopy of chromate treated cells showed characteristic features of apoptosis including chromatin margination and fragmentation, and cytoplasmic condensation with intact membrane and organelle structure. Internucleosomal DNA fragmentation (IDF) was delayed for at least 24 hr, whereafter it was detected in both adherent and nonadherent cells through Day 5 after treatment. These results indicate apoptosis as the mode of cell death caused by chromium and imply that apoptosis must be considered as a component of chromium-induced multistage carcinogenesis.","Apoptosis is the mode of cell death caused by carcinogenic chromium Abs: The role of apoptosis in the mechanism of toxicity of hexavalent chromium, a human carcinogen, was investigated. Chinese hamster ovary (CHO) cells were treated with 150 or 300 microM sodium chromate for 2 hr, doses which decreased colony-forming efficiency to 53 and 5% of control, respectively. Cell growth was inhibited at least up to Day 8 after treatment. DNA synthesis was inhibited to 30 and 19% of control at 1 hr after treatment, and did not begin to recover until Day 4 after treatment. Protein synthesis was inhibited by 52 and 60% in 150 and 300 microM treated cells, respectively, 1 h after treatment, and recovered to 142 and 93%, respectively, at 24 hr. Incubation of cells with nontoxic doses of cycloheximide for 24 hr after treatment produced synergistic toxicity with chromate in colony-forming efficiency assays. Ion gradients persisted to Day 2 as revealed by exclusion of trypan blue dye in 97% of treated cells. Fluorescence microscopy of acridine orange-stained cells revealed morphological features of apoptosis including nuclear fragmentation in more than 90% of detached nonadherent cells and up to 22% of adherent cells by Day 2 after treatment. Untreated cells remained morphologically normal. Transmission electron microscopy of chromate treated cells showed characteristic features of apoptosis including chromatin margination and fragmentation, and cytoplasmic condensation with intact membrane and organelle structure. Internucleosomal DNA fragmentation (IDF) was delayed for at least 24 hr, whereafter it was detected in both adherent and nonadherent cells through Day 5 after treatment. These results indicate apoptosis as the mode of cell death caused by chromium and imply that apoptosis must be considered as a component of chromium-induced multistage carcinogenesis."
1233860,Kiilunen 1994,Occupational exposure to chromium and nickel in Finland--analysis of registries of hygienic measurements and biological monitoring,"Two large data bases, one with the results of analyses on total dust, nickel, total and hexavalent chromium, and the other, with concentrations of chromium and nickel in workers' urine, have been accumulated in the Finnish Institute of Occupational Health. Data were analysed to assess occupational exposure to chromium and nickel during the last decade, using the International Standard Industrial Classifications for grouping industrial activities. Number of analyses was highest in fabricated metal products manufacturing, and welders and sheet metal workers were the largest and most heavily exposed groups. Occupational exposure limits were exceeded in 15.8% of all chromium measurements (500 micrograms m-3 for total chromium and 50 micrograms m-3 for hexavalent chromium). Recommended biological action level (BAL) (1.0 mumol l.-1) was exceeded in 0.8-7.1% of the cases in different years. Altogether, 18.3% (range 7.6-28.3%) of the air nickel measurements were higher than the occupational exposure limit for nickel compounds (100 micrograms m-3), but only 0.2-3.1% of results exceeded the BAL for nickel (1.30 mumol l.-1).","Occupational exposure to chromium and nickel in Finland--analysis of registries of hygienic measurements and biological monitoring Abs: Two large data bases, one with the results of analyses on total dust, nickel, total and hexavalent chromium, and the other, with concentrations of chromium and nickel in workers' urine, have been accumulated in the Finnish Institute of Occupational Health. Data were analysed to assess occupational exposure to chromium and nickel during the last decade, using the International Standard Industrial Classifications for grouping industrial activities. Number of analyses was highest in fabricated metal products manufacturing, and welders and sheet metal workers were the largest and most heavily exposed groups. Occupational exposure limits were exceeded in 15.8% of all chromium measurements (500 micrograms m-3 for total chromium and 50 micrograms m-3 for hexavalent chromium). Recommended biological action level (BAL) (1.0 mumol l.-1) was exceeded in 0.8-7.1% of the cases in different years. Altogether, 18.3% (range 7.6-28.3%) of the air nickel measurements were higher than the occupational exposure limit for nickel compounds (100 micrograms m-3), but only 0.2-3.1% of results exceeded the BAL for nickel (1.30 mumol l.-1)."
1233859,Beyersmann 1994,Interactions in metal carcinogenicity,"The carcinogenicity and genotoxicity of cadmium, chromium, cobalt and nickel strongly depend on their chemical ligands (speciation) which modulate their bioavailability and reactivity with biochemical targets. With the exception of hexavalent chromium, carcinogenic metal compounds are only weakly genotoxic. However, the ions of the carcinogenic metals cadmium, cobalt and nickel, and also the noncarcinogenic lead, inhibit the repair of DNA damaged by direct genotoxic agents like UV irradiation and alkylating substances, thereby enhancing the effects of the latter agents. These effects are interpreted by the interference of the toxic metal ions with biochemical functions of magnesium, calcium and zinc ions.","Interactions in metal carcinogenicity Abs: The carcinogenicity and genotoxicity of cadmium, chromium, cobalt and nickel strongly depend on their chemical ligands (speciation) which modulate their bioavailability and reactivity with biochemical targets. With the exception of hexavalent chromium, carcinogenic metal compounds are only weakly genotoxic. However, the ions of the carcinogenic metals cadmium, cobalt and nickel, and also the noncarcinogenic lead, inhibit the repair of DNA damaged by direct genotoxic agents like UV irradiation and alkylating substances, thereby enhancing the effects of the latter agents. These effects are interpreted by the interference of the toxic metal ions with biochemical functions of magnesium, calcium and zinc ions."
1233858,Sjögren et al. 1994,Exposure to stainless steel welding fumes and lung cancer: a meta-analysis,Stainless steel welding is associated with exposure to metals including hexavalent chromium and nickel. This study is a meta-analysis of five studies of stainless steel welders and the occurrence of lung cancer. Asbestos exposure and smoking habits have been taken into account. The calculated pooled relative risk estimate was 1.94 with a 95% confidence interval of 1.28-2.93. This result suggests a causal relation between exposure to stainless steel welding and lung cancer.,Exposure to stainless steel welding fumes and lung cancer: a meta-analysis Abs: Stainless steel welding is associated with exposure to metals including hexavalent chromium and nickel. This study is a meta-analysis of five studies of stainless steel welders and the occurrence of lung cancer. Asbestos exposure and smoking habits have been taken into account. The calculated pooled relative risk estimate was 1.94 with a 95% confidence interval of 1.28-2.93. This result suggests a causal relation between exposure to stainless steel welding and lung cancer.
1233857,Langård 1994,Nickel-related cancer in welders,"During stainless steel (SS) welding, solid aerosols are generated from elemental compounds which are generally considered to be human carcinogens; i.e. compounds of hexavalent chromium (CrVI) and nickel. Epidemiological studies among groups of SS-welders have indicated that they may carry a higher risk of acquiring lung cancer than mild steel (MS) welders using the same welding techniques. This excess risk has been demonstrated in cohort as well as by case-control studies. The present evidence does not support the view that exposure to SS-welding fumes poses a hazard of cancer at any other site. Exposure to asbestos and smoking are generally major confounders in these studies. The number of SS-welders world-wide seems to be increasing, thus these findings may be of significance to SS-welders and to the welding industry. Despite the information on the possible cancer hazard among SS-welders, current epidemiological data on cancer incidence and mortality do not offer clear evidence to determine whether exposure to nickel or CrVI compounds constitutes the more important risk factor for lung cancer.","Nickel-related cancer in welders Abs: During stainless steel (SS) welding, solid aerosols are generated from elemental compounds which are generally considered to be human carcinogens; i.e. compounds of hexavalent chromium (CrVI) and nickel. Epidemiological studies among groups of SS-welders have indicated that they may carry a higher risk of acquiring lung cancer than mild steel (MS) welders using the same welding techniques. This excess risk has been demonstrated in cohort as well as by case-control studies. The present evidence does not support the view that exposure to SS-welding fumes poses a hazard of cancer at any other site. Exposure to asbestos and smoking are generally major confounders in these studies. The number of SS-welders world-wide seems to be increasing, thus these findings may be of significance to SS-welders and to the welding industry. Despite the information on the possible cancer hazard among SS-welders, current epidemiological data on cancer incidence and mortality do not offer clear evidence to determine whether exposure to nickel or CrVI compounds constitutes the more important risk factor for lung cancer."
1233856,Meert et al. 1994,Acute ammonium dichromate poisoning,"We report the ingestion of ammonium dichromate by a child that resulted in multiple-organ-system failure and death. Exchange transfusion and hemodialysis were ineffective in removing significant amounts of chromium or causing sustained clinical improvement. We suggest that immediate, large doses of the reducing agent ascorbic acid would allow effective reduction of hexavalent chromium with less cellular toxicity.","Acute ammonium dichromate poisoning Abs: We report the ingestion of ammonium dichromate by a child that resulted in multiple-organ-system failure and death. Exchange transfusion and hemodialysis were ineffective in removing significant amounts of chromium or causing sustained clinical improvement. We suggest that immediate, large doses of the reducing agent ascorbic acid would allow effective reduction of hexavalent chromium with less cellular toxicity."
1233855,Bridgewater et al. 1994,Base-specific arrest of in vitro DNA replication by carcinogenic chromium: relationship to DNA interstrand crosslinking,"We have previously shown that trivalent chromium can bind to purified DNA and form lesions capable of obstructing DNA replication in vitro. Trivalent chromium is not, however, carcinogenic to humans. Rather, it is the end product of the intracellular reduction of hexavalent chromium, which is carcinogenic. The process of chromium reduction yields several reactive intermediates which may also interact with DNA, perhaps producing different lesions than those generated when trivalent chromium binds DNA. The present study was undertaken to determine whether the treatment of DNA with hexavalent chromium in the presence of ascorbate (the intracellular reductant responsible for most in vivo chromium reduction), would also generate DNA lesions capable of obstructing replication. Using increasing chromium concentrations and a constant ascorbate:chromium ratio of 0.5:1 to generate biologically relevant adduct levels, a DNA polymerase arrest assay revealed that polymerase arresting lesions were formed and were indistinguishable from those generated by trivalent chromium, in that the most prominent arrests sites were one base upstream of guanine residues on the template strand. Measurement of the amount of chromium bound to template DNA in relation to the number of arrests demonstrated that only a subset (18.5%) of the chromium adducts were capable of causing polymerase arrest. Arrest assays performed with increasing ratios of ascorbate to chromium showed that high ratios (> or = 5:1) resulted in decreased polymerase arrests. DNA interstrand crosslinks in the arrest assay template were detected by renaturing agarose gel electrophoresis, and were shown to decrease markedly with increasing ascorbate to chromium ratios, whereas chromium binding levels remained unchanged. These results strongly implicate DNA interstrand crosslinks as the polymerase arresting lesion. The present study confirms and extends our previous study with trivalent chromium, and suggests that while the initial chemical nature of the DNA lesions formed by either trivalent chromium or reductive intermediates of hexavalent chromium may differ, their effect on DNA replication is the same.","Base-specific arrest of in vitro DNA replication by carcinogenic chromium: relationship to DNA interstrand crosslinking Abs: We have previously shown that trivalent chromium can bind to purified DNA and form lesions capable of obstructing DNA replication in vitro. Trivalent chromium is not, however, carcinogenic to humans. Rather, it is the end product of the intracellular reduction of hexavalent chromium, which is carcinogenic. The process of chromium reduction yields several reactive intermediates which may also interact with DNA, perhaps producing different lesions than those generated when trivalent chromium binds DNA. The present study was undertaken to determine whether the treatment of DNA with hexavalent chromium in the presence of ascorbate (the intracellular reductant responsible for most in vivo chromium reduction), would also generate DNA lesions capable of obstructing replication. Using increasing chromium concentrations and a constant ascorbate:chromium ratio of 0.5:1 to generate biologically relevant adduct levels, a DNA polymerase arrest assay revealed that polymerase arresting lesions were formed and were indistinguishable from those generated by trivalent chromium, in that the most prominent arrests sites were one base upstream of guanine residues on the template strand. Measurement of the amount of chromium bound to template DNA in relation to the number of arrests demonstrated that only a subset (18.5%) of the chromium adducts were capable of causing polymerase arrest. Arrest assays performed with increasing ratios of ascorbate to chromium showed that high ratios (> or = 5:1) resulted in decreased polymerase arrests. DNA interstrand crosslinks in the arrest assay template were detected by renaturing agarose gel electrophoresis, and were shown to decrease markedly with increasing ascorbate to chromium ratios, whereas chromium binding levels remained unchanged. These results strongly implicate DNA interstrand crosslinks as the polymerase arresting lesion. The present study confirms and extends our previous study with trivalent chromium, and suggests that while the initial chemical nature of the DNA lesions formed by either trivalent chromium or reductive intermediates of hexavalent chromium may differ, their effect on DNA replication is the same."
1233853,Gargas et al. 1994,Urinary excretion of chromium following ingestion of chromite-ore processing residues in humans: implications for biomonitoring,"Biomonitoring programs for urinary chromium (Cr) typically attempt to evaluate occupational exposure via the inhalation route. This study investigated whether Cr can be detected in the urine of people following the ingestion of soils that contain relatively high concentrations of chromium in chromite ore processing residue (COPR). To evaluate the reasonableness of using urinary monitoring to assess environmental exposure, six volunteers ingested 400 mg of soil/day (low-dose group), two others ingested 2.0 g of soil/day (high-dose group) for 3 consecutive days, and one person ingested a placebo on each of 3 days. The soil and COPR mixture contained concentrations of total chromium (Cr) and hexavalent chromium [Cr(VI)] of 103 +/- 20 and 9.3 +/- 3.8 mg/kg, respectively. Therefore, the low-dose group ingested 41 micrograms Cr/day [including 3.7 micrograms Cr(VI)] and the high-dose group ingested 206 micrograms Cr/day [including 18.6 micrograms Cr(VI)] on each of 3 consecutive days. All urine samples were collected and analyzed individually for total Cr on the day prior to dosing, during the 3 days of dosing, and up to the first void 48 h after the last dose. No significant increases in urinary Cr excretion were found when background excretion data were compared with data following each of the 3 days of dosing or in daily mean urine concentrations of the high- vs the low-dose groups. It appears that Cr present in a soil and COPR mixture at Cr doses up to 200 micrograms/day is not sufficiently bioavailable for biomonitoring of urine to be informative.(ABSTRACT TRUNCATED AT 250 WORDS)","Urinary excretion of chromium following ingestion of chromite-ore processing residues in humans: implications for biomonitoring Abs: Biomonitoring programs for urinary chromium (Cr) typically attempt to evaluate occupational exposure via the inhalation route. This study investigated whether Cr can be detected in the urine of people following the ingestion of soils that contain relatively high concentrations of chromium in chromite ore processing residue (COPR). To evaluate the reasonableness of using urinary monitoring to assess environmental exposure, six volunteers ingested 400 mg of soil/day (low-dose group), two others ingested 2.0 g of soil/day (high-dose group) for 3 consecutive days, and one person ingested a placebo on each of 3 days. The soil and COPR mixture contained concentrations of total chromium (Cr) and hexavalent chromium [Cr(VI)] of 103 +/- 20 and 9.3 +/- 3.8 mg/kg, respectively. Therefore, the low-dose group ingested 41 micrograms Cr/day [including 3.7 micrograms Cr(VI)] and the high-dose group ingested 206 micrograms Cr/day [including 18.6 micrograms Cr(VI)] on each of 3 consecutive days. All urine samples were collected and analyzed individually for total Cr on the day prior to dosing, during the 3 days of dosing, and up to the first void 48 h after the last dose. No significant increases in urinary Cr excretion were found when background excretion data were compared with data following each of the 3 days of dosing or in daily mean urine concentrations of the high- vs the low-dose groups. It appears that Cr present in a soil and COPR mixture at Cr doses up to 200 micrograms/day is not sufficiently bioavailable for biomonitoring of urine to be informative.(ABSTRACT TRUNCATED AT 250 WORDS)"
1233852,Finley et al. 1995,Risk assessment of the allergic dermatitis potential of environmental exposure to hexavalent chromium,,Risk assessment of the allergic dermatitis potential of environmental exposure to hexavalent chromium Abs: 
1233851,Zhitkovich et al. 1995,Glutathione and free amino acids form stable complexes with DNA following exposure of intact mammalian cells to chromate,"Exposure of cells to carcinogenic Cr(VI) compounds results in the formation of several types of DNA lesions such as strand breaks, DNA-protein crosslinks and uncharacterized DNA-Cr adducts. Hexavalent chromium compounds are positive in most bacterial and eukaryotic mutagenic systems, although the nature of DNA modifications underlying the chromium-induced mutagenesis is not known. Hexavalent chromate(VI) is very active in cellular systems because it is actively transported into cells, but intracellularly it is ultimately reduced to Cr(III). Here we show that exposure of Chinese hamster ovary (CHO) cells to potassium chromate(VI) leads to the formation of stable complexes between DNA and amino acids or glutathione. Cysteine, glutamic acid and histidine were the major amino acids crosslinked to DNA in chromate-treated cells. Incubation of purified DNA in the presence of EDTA dissociated SDS stable amino acid-DNA complexes, which indicates that these DNA adducts are most likely to represent ternary coordination complexes mediated by Cr(III) rather than covalent linkage between amino acids/glutathione and DNA. The amino acids that were found complexed with DNA purified from chromate-exposed cells did not orginate from previously crosslinked proteins during DNA isolation, but represented authentic reactions of free amino acids and glutathione with chromium and DNA in cells. Ternary complexes of glutathione or amino acids with Cr(III) and DNA were estimated to account for as much as 50% of DNA-bound chromium following exposure to < or = 25 microM chromate.","Glutathione and free amino acids form stable complexes with DNA following exposure of intact mammalian cells to chromate Abs: Exposure of cells to carcinogenic Cr(VI) compounds results in the formation of several types of DNA lesions such as strand breaks, DNA-protein crosslinks and uncharacterized DNA-Cr adducts. Hexavalent chromium compounds are positive in most bacterial and eukaryotic mutagenic systems, although the nature of DNA modifications underlying the chromium-induced mutagenesis is not known. Hexavalent chromate(VI) is very active in cellular systems because it is actively transported into cells, but intracellularly it is ultimately reduced to Cr(III). Here we show that exposure of Chinese hamster ovary (CHO) cells to potassium chromate(VI) leads to the formation of stable complexes between DNA and amino acids or glutathione. Cysteine, glutamic acid and histidine were the major amino acids crosslinked to DNA in chromate-treated cells. Incubation of purified DNA in the presence of EDTA dissociated SDS stable amino acid-DNA complexes, which indicates that these DNA adducts are most likely to represent ternary coordination complexes mediated by Cr(III) rather than covalent linkage between amino acids/glutathione and DNA. The amino acids that were found complexed with DNA purified from chromate-exposed cells did not orginate from previously crosslinked proteins during DNA isolation, but represented authentic reactions of free amino acids and glutathione with chromium and DNA in cells. Ternary complexes of glutathione or amino acids with Cr(III) and DNA were estimated to account for as much as 50% of DNA-bound chromium following exposure to < or = 25 microM chromate."
1233850,Yurkow and  Kim 1995,Effects of chromium on basal and insulin-induced tyrosine phosphorylation in H4 hepatoma cells: comparison with phorbol-12-myristate-13-acetate and sodium orthovanadate,"Chromium, in its various forms, is recognized both as a human carcinogen and as a nutrient essential in glucose homeostasis. Although the genotoxicity of this element is associated with its carcinogenic properties, the manner in which chromium mediates its epigenetic effects on cells, including its ability to potentiate insulin action, is not known. In the current studies, Western blotting with antiphosphotyrosine antibodies was used to study the effects of chromium on protein tyrosine phosphorylation in intact H4 rat hepatoma cells. Treatment of cells with hexavalent chromium [Cr(VI)] was found to induce the tyrosine phosphorylation of three prominent sets of proteins, having median molecular masses of 210, 125, and 87 kDa. Cr(VI) pretreatment also inhibited the insulin-induced tyrosine phosphorylation of the major substrate of the insulin receptor kinase, insulin receptor substrate-1, and its subsequent association with the 85-kDa regulatory subunit (p85) of phosphatidylinositol 3'-kinase. Furthermore, Cr(VI) was found to alter the pattern of other p85-binding (insulin-induced) phosphoproteins that were distributed throughout the soluble and particulate fractions of cells. Virtually all of the alterations in basal and insulin-induced phosphorylations associated with Cr(VI) treatment were also observed in cells treated with the protein kinase C (PKC) agonist phorbol-12-myristate-13-acetate. However, the effects of Cr(VI) were determined to be independent of PKC activity, because they were sustained in PKC-depleted cells. The pattern of phosphoproteins induced by Cr(VI) also had similarities to the pattern generated in response to the phosphatase inhibitor sodium orthovanadate. However, several specific differences, including the ability of vanadate to increase insulin receptor beta subunit autophosphorylation [i.e., an effect not observed with Cr(VI)], indicated that these agents modulate phosphorylation by distinct mechanisms. The ability of Cr(VI) to alter the phosphorylation state of key regulatory proteins in a manner similar to that of other biologically active agents suggests a mechanism by which this element can modulate the growth and metabolism of cells.","Effects of chromium on basal and insulin-induced tyrosine phosphorylation in H4 hepatoma cells: comparison with phorbol-12-myristate-13-acetate and sodium orthovanadate Abs: Chromium, in its various forms, is recognized both as a human carcinogen and as a nutrient essential in glucose homeostasis. Although the genotoxicity of this element is associated with its carcinogenic properties, the manner in which chromium mediates its epigenetic effects on cells, including its ability to potentiate insulin action, is not known. In the current studies, Western blotting with antiphosphotyrosine antibodies was used to study the effects of chromium on protein tyrosine phosphorylation in intact H4 rat hepatoma cells. Treatment of cells with hexavalent chromium [Cr(VI)] was found to induce the tyrosine phosphorylation of three prominent sets of proteins, having median molecular masses of 210, 125, and 87 kDa. Cr(VI) pretreatment also inhibited the insulin-induced tyrosine phosphorylation of the major substrate of the insulin receptor kinase, insulin receptor substrate-1, and its subsequent association with the 85-kDa regulatory subunit (p85) of phosphatidylinositol 3'-kinase. Furthermore, Cr(VI) was found to alter the pattern of other p85-binding (insulin-induced) phosphoproteins that were distributed throughout the soluble and particulate fractions of cells. Virtually all of the alterations in basal and insulin-induced phosphorylations associated with Cr(VI) treatment were also observed in cells treated with the protein kinase C (PKC) agonist phorbol-12-myristate-13-acetate. However, the effects of Cr(VI) were determined to be independent of PKC activity, because they were sustained in PKC-depleted cells. The pattern of phosphoproteins induced by Cr(VI) also had similarities to the pattern generated in response to the phosphatase inhibitor sodium orthovanadate. However, several specific differences, including the ability of vanadate to increase insulin receptor beta subunit autophosphorylation [i.e., an effect not observed with Cr(VI)], indicated that these agents modulate phosphorylation by distinct mechanisms. The ability of Cr(VI) to alter the phosphorylation state of key regulatory proteins in a manner similar to that of other biologically active agents suggests a mechanism by which this element can modulate the growth and metabolism of cells."
1233849,Wang and  Shen 1995,Bacterial reduction of hexavalent chromium,"Cr(VI)-reducing bacteria are widespread and Cr(VI) reduction occurs under both aerobic and anaerobic conditions. Under aerobic conditions, both NADH and endogenous cell reserves may serve as the electron donor for Cr(VI) reduction. Under anaerobic conditions, electron transport systems containing cytochromes appear to be involved in Cr(VI) reduction. High cell densities are necessary to obtain a significant rate of Cr(VI) reduction. Cr(VI) reduction by bacteria may be inhibited by Cr(VI), oxygen, heavy metals, and phenolic compounds. The optimum pH and temperature observed for Cr(VI) reduction generally coincide with the optimal growth conditions of cells. The optimum redox potential for Cr(VI) reduction has not yet been established.","Bacterial reduction of hexavalent chromium Abs: Cr(VI)-reducing bacteria are widespread and Cr(VI) reduction occurs under both aerobic and anaerobic conditions. Under aerobic conditions, both NADH and endogenous cell reserves may serve as the electron donor for Cr(VI) reduction. Under anaerobic conditions, electron transport systems containing cytochromes appear to be involved in Cr(VI) reduction. High cell densities are necessary to obtain a significant rate of Cr(VI) reduction. Cr(VI) reduction by bacteria may be inhibited by Cr(VI), oxygen, heavy metals, and phenolic compounds. The optimum pH and temperature observed for Cr(VI) reduction generally coincide with the optimal growth conditions of cells. The optimum redox potential for Cr(VI) reduction has not yet been established."
1233848,Armienta-Hernández and  Rodríguez-Castillo 1995,"Environmental exposure to chromium compounds in the valley of León, México","The effects on the environment and health of the operation of a chromate compounds factory and tanneries in the León valley in central México are discussed. Sampling and analysis of chromium were performed in water, soil, and human urine. Groundwater has been polluted in an area of about 5 km2 by the leaching of a solid factory waste, which results in concentrations up to 50 mg/l of hexavalent chromium. The plume shape and extension appear to be controlled by the prevailing well extraction regime. Total chromium was detected in the soil around the factory as a result of both aerial transport and deposition of dust produced in the chromate process and irrigation with tannery-contaminated water. Analysis of the impact of chromium in air and water on populations with various degrees of exposure revealed that highly harmful health effects were not observed.","Environmental exposure to chromium compounds in the valley of León, México Abs: The effects on the environment and health of the operation of a chromate compounds factory and tanneries in the León valley in central México are discussed. Sampling and analysis of chromium were performed in water, soil, and human urine. Groundwater has been polluted in an area of about 5 km2 by the leaching of a solid factory waste, which results in concentrations up to 50 mg/l of hexavalent chromium. The plume shape and extension appear to be controlled by the prevailing well extraction regime. Total chromium was detected in the soil around the factory as a result of both aerial transport and deposition of dust produced in the chromate process and irrigation with tannery-contaminated water. Analysis of the impact of chromium in air and water on populations with various degrees of exposure revealed that highly harmful health effects were not observed."
1233847,Bagchi et al. 1995,Oxidative stress induced by chronic administration of sodium dichromate [Cr(VI)] to rats,"Chromium occurs in the workplace primarily in the valence forms Cr(III) and Cr(VI). Recent studies have demonstrated that sodium dichromate [Cr(VI)] induces greater oxidative stress as compared with Cr(III), as indicated by the production of reactive oxygen species by peritoneal macrophages and hepatic mitochondria and microsomes, and enhanced excretion of urinary lipid metabolites and hepatic DNA-single strand breaks (SSB) following acute oral administration of Cr(III) and Cr(VI). We have therefore examined the chronic effects of sodium dichromate dihydrate [Cr(VI); 10 mg (33.56 mumol)/kg/day] on hepatic mitochondrial and microsomal lipid peroxidation, enhanced excretion of urinary lipid metabolites including malondialdehyde (MDA), formaldehyde (FA), acetaldehyde (ACT), acetone (ACON) and propionaldehyde (PROP), and hepatic DNA damage over a period of 90 days. The maximal increases in hepatic lipid peroxidation and DNA damage were observed at approximately 45 days of treatment. Maximum increases in the urinary excretion of MDA, FA, ACT, ACON and PROP were 3.2-, 2.6-, 4.1-, 3.3- and 2.1-fold, respectively, while a 5.2-fold increase in DNA-SSB was observed. The results clearly indicate that chronic sodium dichromate administration induces oxidative stress resulting in tissue damaging effects which may contribute to the toxicity and carcinogenicity of hexavalent chromium.","Oxidative stress induced by chronic administration of sodium dichromate [Cr(VI)] to rats Abs: Chromium occurs in the workplace primarily in the valence forms Cr(III) and Cr(VI). Recent studies have demonstrated that sodium dichromate [Cr(VI)] induces greater oxidative stress as compared with Cr(III), as indicated by the production of reactive oxygen species by peritoneal macrophages and hepatic mitochondria and microsomes, and enhanced excretion of urinary lipid metabolites and hepatic DNA-single strand breaks (SSB) following acute oral administration of Cr(III) and Cr(VI). We have therefore examined the chronic effects of sodium dichromate dihydrate [Cr(VI); 10 mg (33.56 mumol)/kg/day] on hepatic mitochondrial and microsomal lipid peroxidation, enhanced excretion of urinary lipid metabolites including malondialdehyde (MDA), formaldehyde (FA), acetaldehyde (ACT), acetone (ACON) and propionaldehyde (PROP), and hepatic DNA damage over a period of 90 days. The maximal increases in hepatic lipid peroxidation and DNA damage were observed at approximately 45 days of treatment. Maximum increases in the urinary excretion of MDA, FA, ACT, ACON and PROP were 3.2-, 2.6-, 4.1-, 3.3- and 2.1-fold, respectively, while a 5.2-fold increase in DNA-SSB was observed. The results clearly indicate that chronic sodium dichromate administration induces oxidative stress resulting in tissue damaging effects which may contribute to the toxicity and carcinogenicity of hexavalent chromium."
1233846,Campos et al. 1995,Hexavalent-chromium reduction by a chromate-resistant Bacillus sp. strain,"Bacillus strain QC1-2, isolated from a chromium-polluted zone, was selected by its high ability to both tolerate and reduce hexavalent chromium [Cr(VI)] to less-toxic trivalent chromium [Cr(III)]. Cell suspensions of strain QC1-2 rapidly reduced Cr(VI), in both aerobic and anaerobic conditions, to Cr(III) which remained in the supernatant. Cr(VI) reduction was dependent on the addition of glucose but sulfate, an inhibitor of chromate transport, had no effect. Studies with permeabilized cells and cell extracts showed that the Cr(VI) reductase of strain QC1-2 is a soluble NADH-dependent enzyme.","Hexavalent-chromium reduction by a chromate-resistant Bacillus sp. strain Abs: Bacillus strain QC1-2, isolated from a chromium-polluted zone, was selected by its high ability to both tolerate and reduce hexavalent chromium [Cr(VI)] to less-toxic trivalent chromium [Cr(III)]. Cell suspensions of strain QC1-2 rapidly reduced Cr(VI), in both aerobic and anaerobic conditions, to Cr(III) which remained in the supernatant. Cr(VI) reduction was dependent on the addition of glucose but sulfate, an inhibitor of chromate transport, had no effect. Studies with permeabilized cells and cell extracts showed that the Cr(VI) reductase of strain QC1-2 is a soluble NADH-dependent enzyme."
1233844,Kim and  Yurkow 1996,Chromium induces a persistent activation of mitogen-activated protein kinases by a redox-sensitive mechanism in H4 rat hepatoma cells,"Chromium is an important industrial metal, an environmental pollutant, and a human carcinogen. To investigate the mechanisms of chromium-induced carcinogenesis, activation of mitogen-activated protein (MAP) kinases ERK1 and ERK2 was examined in rat hepatoma cells following exposure to hexavalent chromium (Cr(VI)). Cr(VI) was found to activate both forms of MAP kinase in a dose- and time-dependent manner. In contrast to the protein kinase C (PKC) agonist, phorbol 12-myristate 13-acetate, which induced a transient activation of MAP kinases, Cr(VI) caused persistent activation of these enzymes. Furthermore, unlike phorbol 12-myristate 13-acetate, the ability of chromium to activate MAP kinases was found to be independent of PKC since chromium-induced MAP kinase activation occurred in PKC-depleted cells. Stimulation of ERK1 and ERK2 was associated with the ability of Cr(VI) to increase cellular peroxide levels as determined using the H2O2-sensitive fluorescent probe 2',7'-dichlorofluorescein diacetate and flow cytometry. Furthermore, the activation of these kinases by chromium was enhanced in cells treated with the glutathione-depleting agent, L-buthionine-[S,R]-sulfoximine, and attenuated in cells pretreated with an agent that elevates cellular levels of glutathione (i.e., N-acetyl-L-cysteine). The ability of chromium to modulate MAP kinase activity in this manner suggests a mechanism of chromium-induced carcinogenesis that involves the persistent stimulation of cellular regulatory pathways.","Chromium induces a persistent activation of mitogen-activated protein kinases by a redox-sensitive mechanism in H4 rat hepatoma cells Abs: Chromium is an important industrial metal, an environmental pollutant, and a human carcinogen. To investigate the mechanisms of chromium-induced carcinogenesis, activation of mitogen-activated protein (MAP) kinases ERK1 and ERK2 was examined in rat hepatoma cells following exposure to hexavalent chromium (Cr(VI)). Cr(VI) was found to activate both forms of MAP kinase in a dose- and time-dependent manner. In contrast to the protein kinase C (PKC) agonist, phorbol 12-myristate 13-acetate, which induced a transient activation of MAP kinases, Cr(VI) caused persistent activation of these enzymes. Furthermore, unlike phorbol 12-myristate 13-acetate, the ability of chromium to activate MAP kinases was found to be independent of PKC since chromium-induced MAP kinase activation occurred in PKC-depleted cells. Stimulation of ERK1 and ERK2 was associated with the ability of Cr(VI) to increase cellular peroxide levels as determined using the H2O2-sensitive fluorescent probe 2',7'-dichlorofluorescein diacetate and flow cytometry. Furthermore, the activation of these kinases by chromium was enhanced in cells treated with the glutathione-depleting agent, L-buthionine-[S,R]-sulfoximine, and attenuated in cells pretreated with an agent that elevates cellular levels of glutathione (i.e., N-acetyl-L-cysteine). The ability of chromium to modulate MAP kinase activity in this manner suggests a mechanism of chromium-induced carcinogenesis that involves the persistent stimulation of cellular regulatory pathways."
1233843,Graf and  Würgler 1996,The somatic white-ivory eye spot test does not detect the same spectrum of genotoxic events as the wing somatic mutation and recombination test in Drosophila melanogaster,"A groups of six chemical compounds was tested in parallel in two different somatic genotoxicity assays in Drosophila melanogaster, the wing somatic mutation and recombination test (SMART) and the white-ivory eye spot test. The wing spot test makes use of the wing cell markers multiple wing hairs (mwh) and flare (flr) and detects both mitotic recombination and various types of mutational events. The white-ivory eye spot test makes use of the white-ivory (wi) quadruplication and detects the somatic reversion of the recessive eye color mutation wi to the wild-type (w+). Three- or two-day-old larvae were fed chronically with the compounds ethylnitrosourea (ENU), N-nitrosopyrrolidine (NNP), caffeine (CAF), chromium (VI) oxide (CRO), potassium chromate (POC), and 2,4-dichlorophenoxyacetic acid (2,4-D). All six compounds are genotoxic to various degrees in the wing spot test. The percentage of the genotoxic activity that is due to mitotic recombination was between 84% and 91% for the hexavalent chromium compounds CRO and POC and about 68% for 2,4-D. In contrast, ENU and NNP showed only 46% and 25% recombinagenic activity, respectively. In the white-ivory eye spot test, the three compounds (CRO, POC, and 2,4-D) with high recombinagenic activity and CAF were clearly nongenotoxic, whereas only ENU and NNP gave a positive response. From these results, it is concluded that the spectrum of genotoxic events detected by the two assays is different. In particular, the white-ivory eye spot test appears not to detect mitotic recombination the way the wing spot test does.","The somatic white-ivory eye spot test does not detect the same spectrum of genotoxic events as the wing somatic mutation and recombination test in Drosophila melanogaster Abs: A groups of six chemical compounds was tested in parallel in two different somatic genotoxicity assays in Drosophila melanogaster, the wing somatic mutation and recombination test (SMART) and the white-ivory eye spot test. The wing spot test makes use of the wing cell markers multiple wing hairs (mwh) and flare (flr) and detects both mitotic recombination and various types of mutational events. The white-ivory eye spot test makes use of the white-ivory (wi) quadruplication and detects the somatic reversion of the recessive eye color mutation wi to the wild-type (w+). Three- or two-day-old larvae were fed chronically with the compounds ethylnitrosourea (ENU), N-nitrosopyrrolidine (NNP), caffeine (CAF), chromium (VI) oxide (CRO), potassium chromate (POC), and 2,4-dichlorophenoxyacetic acid (2,4-D). All six compounds are genotoxic to various degrees in the wing spot test. The percentage of the genotoxic activity that is due to mitotic recombination was between 84% and 91% for the hexavalent chromium compounds CRO and POC and about 68% for 2,4-D. In contrast, ENU and NNP showed only 46% and 25% recombinagenic activity, respectively. In the white-ivory eye spot test, the three compounds (CRO, POC, and 2,4-D) with high recombinagenic activity and CAF were clearly nongenotoxic, whereas only ENU and NNP gave a positive response. From these results, it is concluded that the spectrum of genotoxic events detected by the two assays is different. In particular, the white-ivory eye spot test appears not to detect mitotic recombination the way the wing spot test does."
1233842,Turick et al. 1996,Isolation of hexavalent chromium-reducing anaerobes from hexavalent-chromium-contaminated and noncontaminated environments,"Hexavalent chromium [Cr(VI)], is a toxic, water-soluble contaminant present in many soils and industrial effluents. Bacteria from various soils were examined for Cr(VI) resistance and reducing potential. Microbes selected from both Cr(VI)-contaminated and -noncontaminated soils and sediments were capable of catalyzing the reduction of Cr(VI) to Cr(III) a less toxic, less water-soluble form of Cr, demonstrating the utility of using a selection strategy for indigenous Cr(VI)-reducing bacteria in a bioprocess. As a result, indigenous Cr(VI)- reducing microbes from contaminated sites should provide the means for developing a bioprocess to reduce Cr(VI) to Cr(III) in nonsterile effluents such as those from soil washes. This approach also avoids the contamination problems associated with pure cultures of allochthonous microorganisms. In addition the apparent ubiquity of Cr(VI)-reducing bacteria in soil and sediments indicates potential for in situ bioremediation of Cr(VI)-contaminated soils and ground water.","Isolation of hexavalent chromium-reducing anaerobes from hexavalent-chromium-contaminated and noncontaminated environments Abs: Hexavalent chromium [Cr(VI)], is a toxic, water-soluble contaminant present in many soils and industrial effluents. Bacteria from various soils were examined for Cr(VI) resistance and reducing potential. Microbes selected from both Cr(VI)-contaminated and -noncontaminated soils and sediments were capable of catalyzing the reduction of Cr(VI) to Cr(III) a less toxic, less water-soluble form of Cr, demonstrating the utility of using a selection strategy for indigenous Cr(VI)-reducing bacteria in a bioprocess. As a result, indigenous Cr(VI)- reducing microbes from contaminated sites should provide the means for developing a bioprocess to reduce Cr(VI) to Cr(III) in nonsterile effluents such as those from soil washes. This approach also avoids the contamination problems associated with pure cultures of allochthonous microorganisms. In addition the apparent ubiquity of Cr(VI)-reducing bacteria in soil and sediments indicates potential for in situ bioremediation of Cr(VI)-contaminated soils and ground water."
1233841,Maslia et al. 1996,Use of computational models to reconstruct and predict trichloroethylene exposure,"In this study, a type frequently encountered by ATSDR, groundwater and surface-water contamination have occurred near the Gratuity Road site in the town of Groton, Massachusetts. A petitioned public health assessment for the Gratuity Road site identified the primary contaminants as trichloro-ethylene (TCE), 1,1,1-trichloroethane (TCA), hexavalent chromium (Cr+6), chromium (Cr), and lead (Pb) (ATSDR 1992). The health assessment also indicated that off-site residential groundwater wells had been contaminated with TCE and TCA. Because direct measures of historical exposure to TCE are unavailable for the Gratuity Road site, computational models were used to reconstruct and predict exposure to TCE. These computational models included environmental transport and exposure models. For the environmental transport models, numerical methods were used to approximate the equations of groundwater flow and contaminant transport. Results of using environmental transport models provided us with the spatial and temporal database necessary to conduct an exposure analysis. This database indicated that groundwater concentrations of TCE typically exceeded EPA's MCL of 5 ppb for TCE. The study demonstrated that although a hazardous waste site can be remediated, nearby populations may experience significant exposure because of historical contamination, which will not be captured by remediation activities. The exposure analysis used simulated concentrations of TCE predicted by environmental transport models. These concentrations were used to compare exposure to TCE from inhalation in a one-compartment model shower with exposure from ingestion of domestic water contaminated by TCE. The exposure model indicated that exposure to TCE by the inhalation route during showering is nearly identical to exposure by ingestion of domestic water supplies contaminated with TCE. As a result, entry by inhalation route is as important as entry by ingestion route when conducting exposure analyses of contamination from volatile organic compounds such as TCE.","Use of computational models to reconstruct and predict trichloroethylene exposure Abs: In this study, a type frequently encountered by ATSDR, groundwater and surface-water contamination have occurred near the Gratuity Road site in the town of Groton, Massachusetts. A petitioned public health assessment for the Gratuity Road site identified the primary contaminants as trichloro-ethylene (TCE), 1,1,1-trichloroethane (TCA), hexavalent chromium (Cr+6), chromium (Cr), and lead (Pb) (ATSDR 1992). The health assessment also indicated that off-site residential groundwater wells had been contaminated with TCE and TCA. Because direct measures of historical exposure to TCE are unavailable for the Gratuity Road site, computational models were used to reconstruct and predict exposure to TCE. These computational models included environmental transport and exposure models. For the environmental transport models, numerical methods were used to approximate the equations of groundwater flow and contaminant transport. Results of using environmental transport models provided us with the spatial and temporal database necessary to conduct an exposure analysis. This database indicated that groundwater concentrations of TCE typically exceeded EPA's MCL of 5 ppb for TCE. The study demonstrated that although a hazardous waste site can be remediated, nearby populations may experience significant exposure because of historical contamination, which will not be captured by remediation activities. The exposure analysis used simulated concentrations of TCE predicted by environmental transport models. These concentrations were used to compare exposure to TCE from inhalation in a one-compartment model shower with exposure from ingestion of domestic water contaminated by TCE. The exposure model indicated that exposure to TCE by the inhalation route during showering is nearly identical to exposure by ingestion of domestic water supplies contaminated with TCE. As a result, entry by inhalation route is as important as entry by ingestion route when conducting exposure analyses of contamination from volatile organic compounds such as TCE."
1233839,Finley et al. 1996,Urinary chromium concentrations in humans following ingestion of safe doses of hexavalent and trivalent chromium: implications for biomonitoring,"In this study, we evaluate the significance of increased urinary chromium concentrations as a marker of chromium exposure and potential health risk. Six human volunteers ingested trivalent chromium [Cr(III)] and hexavalent chromium [Cr(VI)] at doses that are known to be safe but are much higher than typical dietary levels. The following dosing regimen was used: d 1-7, 200 micrograms/d chromium picolinate (a dietary supplement); d 8-10, Cr(VI) ingestion at the U.S. Environmental Protection Agency (EPA) reference dose (RfD) of 0.005 mg/kg/d; d 11-13, no dose; d 14-16, Cr(III) ingestion at the U.S. EPA RfD of 1.0 mg/ kg/d; and d 17-18, postdose. Urine voids were collected throughout the dosing periods and analyzed for chromium. Our findings are as follows: (1) ingestion of 200 micrograms/d of chromium picolinate yielded significantly elevated urine concentrations such that each participant routinely exceeded background, (2) ingestion of the Cr(VI) RfD (0.005 mg/kg/d) yielded individual mean urinary chromium levels (1.2-23 micrograms/L) and a pooled mean urinary chromium level (2.4 micrograms/L) that significantly exceeded background, and (3) ingestion of the Cr(III) RfD yielded no significant increase in urinary chromium concentrations, indicating that little, if any, absorption occurred. Our work identified three critical issues that need to be accounted for in any future studies that will use urinary chromium as a marker of exposure. First, a minimum urinary chromium concentration of approximately 2 micrograms/L should be used as a screening level to critically identify individuals who may have experienced elevated exposures to chromium. Second, if Cr(III) levels in soils are known to be less than 80,000 ppm and the Cr(III) is insoluble, urinary chromium concentrations are not an appropriate marker of exposure. Third, newer forms of chromium supplements that contain organic forms of Cr(III) must be considered potential confounders and their contribution to residential chromium uptake must be carefully evaluated.","Urinary chromium concentrations in humans following ingestion of safe doses of hexavalent and trivalent chromium: implications for biomonitoring Abs: In this study, we evaluate the significance of increased urinary chromium concentrations as a marker of chromium exposure and potential health risk. Six human volunteers ingested trivalent chromium [Cr(III)] and hexavalent chromium [Cr(VI)] at doses that are known to be safe but are much higher than typical dietary levels. The following dosing regimen was used: d 1-7, 200 micrograms/d chromium picolinate (a dietary supplement); d 8-10, Cr(VI) ingestion at the U.S. Environmental Protection Agency (EPA) reference dose (RfD) of 0.005 mg/kg/d; d 11-13, no dose; d 14-16, Cr(III) ingestion at the U.S. EPA RfD of 1.0 mg/ kg/d; and d 17-18, postdose. Urine voids were collected throughout the dosing periods and analyzed for chromium. Our findings are as follows: (1) ingestion of 200 micrograms/d of chromium picolinate yielded significantly elevated urine concentrations such that each participant routinely exceeded background, (2) ingestion of the Cr(VI) RfD (0.005 mg/kg/d) yielded individual mean urinary chromium levels (1.2-23 micrograms/L) and a pooled mean urinary chromium level (2.4 micrograms/L) that significantly exceeded background, and (3) ingestion of the Cr(III) RfD yielded no significant increase in urinary chromium concentrations, indicating that little, if any, absorption occurred. Our work identified three critical issues that need to be accounted for in any future studies that will use urinary chromium as a marker of exposure. First, a minimum urinary chromium concentration of approximately 2 micrograms/L should be used as a screening level to critically identify individuals who may have experienced elevated exposures to chromium. Second, if Cr(III) levels in soils are known to be less than 80,000 ppm and the Cr(III) is insoluble, urinary chromium concentrations are not an appropriate marker of exposure. Third, newer forms of chromium supplements that contain organic forms of Cr(III) must be considered potential confounders and their contribution to residential chromium uptake must be carefully evaluated."
1233836,Bick et al. 1996,Hodgkin's disease in association with hexavalent chromium exposure,"During an epidemiological study assessing cancer risk in a small isolated population exposed to excessive amounts of hexavalent chromium, we noted two patients with Hodgkin's disease after exposure for many years and after a long latency period. The study population demonstrated an observed risk between 65 and 92 times that of reported risks for non-exposed US populations. Although malignant lymphoma, as well as many other malignancies, has clearly been associated with hexavalent chromium exposure, no reports have yet specifically mentioned Hodgkin's disease. We herein report Hodgkin's disease specifically in two individuals so exposed. Although this may be a chance occurrence, clinicians should be aware of the potential association between hexavalent chromium exposure and Hodgkin's lymphoma.","Hodgkin's disease in association with hexavalent chromium exposure Abs: During an epidemiological study assessing cancer risk in a small isolated population exposed to excessive amounts of hexavalent chromium, we noted two patients with Hodgkin's disease after exposure for many years and after a long latency period. The study population demonstrated an observed risk between 65 and 92 times that of reported risks for non-exposed US populations. Although malignant lymphoma, as well as many other malignancies, has clearly been associated with hexavalent chromium exposure, no reports have yet specifically mentioned Hodgkin's disease. We herein report Hodgkin's disease specifically in two individuals so exposed. Although this may be a chance occurrence, clinicians should be aware of the potential association between hexavalent chromium exposure and Hodgkin's lymphoma."
1233835,Mancuso 1997,Chromium as an industrial carcinogen: Part I,"Successive cohorts by year of hire at the same chromate plant (1931-1932, 1933-1934, 1935-1937) and the combined cohort (1931-1937) of 332 employees were followed through 1993. A total of 283 deaths (85%) of the total cohort were identified. In the combined cohort (1931-1937), 66 lung cancers were found, constituting 23.3% of all deaths and 64.7% of all cancers. The lung cancer mortality rates are shown over a span of decades, from 15 years to over 55 years, with progressive rise. Observations of lung cancer identified, employees not found, and cancer risk by age at hire are cited. Lung cancer death rates increased by gradient level of exposure to insoluble (trivalent) chromium and to soluble (hexavalent) chromium, with a pattern of increase by total chromium. Age-specific death rates for lung cancer according to the same gradient exposure range for total, insoluble, and soluble chromium are presented. The potential cancer risk extends to all forms of chromium and to total chromium.","Chromium as an industrial carcinogen: Part I Abs: Successive cohorts by year of hire at the same chromate plant (1931-1932, 1933-1934, 1935-1937) and the combined cohort (1931-1937) of 332 employees were followed through 1993. A total of 283 deaths (85%) of the total cohort were identified. In the combined cohort (1931-1937), 66 lung cancers were found, constituting 23.3% of all deaths and 64.7% of all cancers. The lung cancer mortality rates are shown over a span of decades, from 15 years to over 55 years, with progressive rise. Observations of lung cancer identified, employees not found, and cancer risk by age at hire are cited. Lung cancer death rates increased by gradient level of exposure to insoluble (trivalent) chromium and to soluble (hexavalent) chromium, with a pattern of increase by total chromium. Age-specific death rates for lung cancer according to the same gradient exposure range for total, insoluble, and soluble chromium are presented. The potential cancer risk extends to all forms of chromium and to total chromium."
1233834,Elbetieha and  Al-Hamood 1997,Long-term exposure of male and female mice to trivalent and hexavalent chromium compounds: effect on fertility,"Sexually mature male and female mice at 50 days of age were exposed to trivalent (Chromium chloride) or hexavalent (potassium dichromate) chromium compounds in drinking water for 12 weeks. The effects of the direct chromium exposure on fertility was assessed at day 140 of age. Fertility was significantly reduced in males exposed to the trivalent chromium compound. The number of implantation sites and the number of viable fetuses was significantly reduced in females impregnated by males exposed to the hexavalent chromium compound. The number of resorptions and dead fetuses was increased in females impregnated by males exposed to trivalent and hexavalent chromium compounds. The exposure of female mice to trivalent and hexavalent chromium compounds significantly reduced the number of implantation sites and the number of viable fetuses. The number of females with resorptions was significantly increased in hexavalent chromium exposed females. The number of resorptions was increased in trivalent and hexavalent exposed females. Body, seminal vesicles and preputial gland weights were significantly reduced in males exposed to trivalent and hexavalent chromium, whereas testes weight was significantly increased in males exposed to these compounds. Furthermore, ovarian weight was significantly increased in females exposed to trivalent and hexavalent chromium, whereas uterine weight was significantly decreased in trivalent chromium exposed females. In conclusion, the ingestion of trivalent and hexavalent chromium compounds by adult male and female mice would cause adverse effects on fertility and reproduction.","Long-term exposure of male and female mice to trivalent and hexavalent chromium compounds: effect on fertility Abs: Sexually mature male and female mice at 50 days of age were exposed to trivalent (Chromium chloride) or hexavalent (potassium dichromate) chromium compounds in drinking water for 12 weeks. The effects of the direct chromium exposure on fertility was assessed at day 140 of age. Fertility was significantly reduced in males exposed to the trivalent chromium compound. The number of implantation sites and the number of viable fetuses was significantly reduced in females impregnated by males exposed to the hexavalent chromium compound. The number of resorptions and dead fetuses was increased in females impregnated by males exposed to trivalent and hexavalent chromium compounds. The exposure of female mice to trivalent and hexavalent chromium compounds significantly reduced the number of implantation sites and the number of viable fetuses. The number of females with resorptions was significantly increased in hexavalent chromium exposed females. The number of resorptions was increased in trivalent and hexavalent exposed females. Body, seminal vesicles and preputial gland weights were significantly reduced in males exposed to trivalent and hexavalent chromium, whereas testes weight was significantly increased in males exposed to these compounds. Furthermore, ovarian weight was significantly increased in females exposed to trivalent and hexavalent chromium, whereas uterine weight was significantly decreased in trivalent chromium exposed females. In conclusion, the ingestion of trivalent and hexavalent chromium compounds by adult male and female mice would cause adverse effects on fertility and reproduction."
1233833,Felter and  Dourson 1997,Hexavalent chromium-contaminated soils: options for risk assessment and risk management,"Risk assessment involves establishing scientifically defensible dose-response relationships for end points of concern. For Cr(VI)-contaminated soils, this includes conducting dose-response assessments for blood, liver, and kidney toxicity following oral exposure; lung cancer following inhalation exposure; and allergic contact dermatitis following dermal exposure. This dose-response information is then integrated with a site-specific exposure assessment (or default assumptions) in order to develop a site-specific (or generic) soil criterion within the framework of a comprehensive risk characterization. Risk managers develop cleanup standards designed to protect against all possible adverse effects, taking into account these site-specific (or generic) criteria and other factors such as technical feasibility, cost-benefit analyses, and socio-political concerns. Recently a push for cost-benefit analyses of environmental decisions has occurred, further supporting the need for risk assessors to prepare a comprehensive risk characterization, with its attendant uncertainties. These risk assessment and management issues are brought to the forefront by risk assessors and risk managers dealing with Cr(VI)-contaminated soils. This article offers a review and analysis of the risk characterization of Cr(VI)-contaminated soils, showing that the differing toxicities with route of exposures do not necessarily lead to different characterizations or risk. Soil concentrations in the range of 130 to 450 ppm appear to protect against noncancer toxicity from oral exposure, cancer toxicity from inhalation exposure, and allergic contact dermatitis from dermal exposure.","Hexavalent chromium-contaminated soils: options for risk assessment and risk management Abs: Risk assessment involves establishing scientifically defensible dose-response relationships for end points of concern. For Cr(VI)-contaminated soils, this includes conducting dose-response assessments for blood, liver, and kidney toxicity following oral exposure; lung cancer following inhalation exposure; and allergic contact dermatitis following dermal exposure. This dose-response information is then integrated with a site-specific exposure assessment (or default assumptions) in order to develop a site-specific (or generic) soil criterion within the framework of a comprehensive risk characterization. Risk managers develop cleanup standards designed to protect against all possible adverse effects, taking into account these site-specific (or generic) criteria and other factors such as technical feasibility, cost-benefit analyses, and socio-political concerns. Recently a push for cost-benefit analyses of environmental decisions has occurred, further supporting the need for risk assessors to prepare a comprehensive risk characterization, with its attendant uncertainties. These risk assessment and management issues are brought to the forefront by risk assessors and risk managers dealing with Cr(VI)-contaminated soils. This article offers a review and analysis of the risk characterization of Cr(VI)-contaminated soils, showing that the differing toxicities with route of exposures do not necessarily lead to different characterizations or risk. Soil concentrations in the range of 130 to 450 ppm appear to protect against noncancer toxicity from oral exposure, cancer toxicity from inhalation exposure, and allergic contact dermatitis from dermal exposure."
1233832,Snyder et al. 1997,An assessment of the tumorigenic properties of a Hudson County soil sample heavily contaminated with hexavalent chromium,"During much of this century, Hudson County, New Jersey, was a major center for the processing of chromium ore. Some of the residue from this processing was used in landfills and in construction materials throughout the county and, in some cases, in highly populated areas. Given that it is widely accepted that exposure to hexavalent chromium compounds poses a risk for the development of respiratory-tract cancer, concerns were raised that individuals who worked or resided in chromium-contaminated areas might be at increased risk for the development of respiratory cancer. To address these concerns, we evaluated a Hudson County soil sample-heavily contaminated with chromium ore residue (Cr(+6) concentration at 5 895 mg/kg)-with respect to its carcinogenic potential to the respiratory tract of Sprague-Dawley rats. Groups of animals were given repeated intratracheal exposures to one of four materials: (1) Hudson County chromium-contaminated soil (CCS), (2) CCS augmented with calcium chromate (CaCrO4), (3) CaCrO4 alone, or (4) control soil. Nominal total doses of Cr(+6) for each respective group were 324 microg/kg, 7,975 microg/kg, 8,700 microg/kg, and 0.02 microg/kg. Incidences of malignant tumors and nephritis were not elevated in any group. Four primary lung tumors appeared in animals that received CCS + CaCrO4, and one primary lung tumor appeared in the group treated with CaCrO4 alone. These incidences were not significant statistically, but the rare spontaneous occurrence of these tumors in Sprague-Dawley rats suggested that they were treatment related. No primary lung tumors appeared in the control or CCS-treated groups.","An assessment of the tumorigenic properties of a Hudson County soil sample heavily contaminated with hexavalent chromium Abs: During much of this century, Hudson County, New Jersey, was a major center for the processing of chromium ore. Some of the residue from this processing was used in landfills and in construction materials throughout the county and, in some cases, in highly populated areas. Given that it is widely accepted that exposure to hexavalent chromium compounds poses a risk for the development of respiratory-tract cancer, concerns were raised that individuals who worked or resided in chromium-contaminated areas might be at increased risk for the development of respiratory cancer. To address these concerns, we evaluated a Hudson County soil sample-heavily contaminated with chromium ore residue (Cr(+6) concentration at 5 895 mg/kg)-with respect to its carcinogenic potential to the respiratory tract of Sprague-Dawley rats. Groups of animals were given repeated intratracheal exposures to one of four materials: (1) Hudson County chromium-contaminated soil (CCS), (2) CCS augmented with calcium chromate (CaCrO4), (3) CaCrO4 alone, or (4) control soil. Nominal total doses of Cr(+6) for each respective group were 324 microg/kg, 7,975 microg/kg, 8,700 microg/kg, and 0.02 microg/kg. Incidences of malignant tumors and nephritis were not elevated in any group. Four primary lung tumors appeared in animals that received CCS + CaCrO4, and one primary lung tumor appeared in the group treated with CaCrO4 alone. These incidences were not significant statistically, but the rare spontaneous occurrence of these tumors in Sprague-Dawley rats suggested that they were treatment related. No primary lung tumors appeared in the control or CCS-treated groups."
1233831,Moulin 1997,A meta-analysis of epidemiologic studies of lung cancer in welders,"<strong>OBJECTIVE: </strong>A meta-analysis of epidemiologic studies was carried out on lung cancer risk among shipyard, mild steel, and stainless steel welders, and the role of asbestos exposure and smoking was considered.<br /><br /><strong>METHODS: </strong>The meta-analysis consisted of calculating combined relative risks (RR) and their variances through a logarithm transformation of published RR values and a weighing using the inverted variance of each RR.<br /><br /><strong>RESULTS: </strong>The literature provided 18 case-referent and 31 cohort studies. The combined RR values were 1.38 [observed 1028, 95% confidence interval (95% CI) 1.29-1.48] for &quot;all or unspecified welding categories&quot;, 1.30 (observed 305, 95% CI 1.14-1.48) for shipyard welders, and 1.35 (observed 173, 95% CI 1.15-1.58) for nonshipyard welders. Similar combined RR values (RR) were observed for mild steel welders (combined RR 1.50, observed 137, 95% CI 1.18-1.91) and stainless steel welders (combined RR 1.50 observed 114, 95% CI 1.10-2.05). No significant heterogeneity was discerned between studies of any welding or study design category. A marked healthy worker effect may also lead to an underestimation of the standardized mortality ratio for lung cancer among stainless steel welders. Furthermore, welders of any category are likely to be exposed to asbestos. Welders also seem to smoke more than the general male population, and therefore the hypothesis of tobacco overconsumption among welders could not be discarded.<br /><br /><strong>CONCLUSIONS: </strong>A 30-40% increase in the RR of lung cancer among welders cannot be explained by hexavalent chromium and nickel exposure among stainless steel welders. The combination of the carcinogenic effects of asbestos exposure and smoking may account for part of the lung cancer excess observed.","A meta-analysis of epidemiologic studies of lung cancer in welders Abs: <strong>OBJECTIVE: </strong>A meta-analysis of epidemiologic studies was carried out on lung cancer risk among shipyard, mild steel, and stainless steel welders, and the role of asbestos exposure and smoking was considered.<br /><br /><strong>METHODS: </strong>The meta-analysis consisted of calculating combined relative risks (RR) and their variances through a logarithm transformation of published RR values and a weighing using the inverted variance of each RR.<br /><br /><strong>RESULTS: </strong>The literature provided 18 case-referent and 31 cohort studies. The combined RR values were 1.38 [observed 1028, 95% confidence interval (95% CI) 1.29-1.48] for &quot;all or unspecified welding categories&quot;, 1.30 (observed 305, 95% CI 1.14-1.48) for shipyard welders, and 1.35 (observed 173, 95% CI 1.15-1.58) for nonshipyard welders. Similar combined RR values (RR) were observed for mild steel welders (combined RR 1.50, observed 137, 95% CI 1.18-1.91) and stainless steel welders (combined RR 1.50 observed 114, 95% CI 1.10-2.05). No significant heterogeneity was discerned between studies of any welding or study design category. A marked healthy worker effect may also lead to an underestimation of the standardized mortality ratio for lung cancer among stainless steel welders. Furthermore, welders of any category are likely to be exposed to asbestos. Welders also seem to smoke more than the general male population, and therefore the hypothesis of tobacco overconsumption among welders could not be discarded.<br /><br /><strong>CONCLUSIONS: </strong>A 30-40% increase in the RR of lung cancer among welders cannot be explained by hexavalent chromium and nickel exposure among stainless steel welders. The combination of the carcinogenic effects of asbestos exposure and smoking may account for part of the lung cancer excess observed."
1233830,Huvinen et al. 1997,Estimation of individual dust exposure by magnetopneumography in stainless steel production,"The objectives of the study were to measure the magnetic dust lung burden of workers in stainless steel production by magnetopneumography (MPG) and to investigate the relationship of the results with air-borne concentrations of dust, total and hexavalent chromium as well as urinary excretion of chromium. There were 128 workers from the chromite mine, sintering plant, ferrochrome smelter, stainless steel smelting shop, cold rolling mill and welding shop in the exposed groups and five persons from the office staff in the control group. The remanent magnetic field (RMF) in the lungs was slightly elevated among workers in the ferrochromium and steel smelting shops; the levels were, however, lower than those reported for welders earlier and those observed in the welding/repair shop. Workers in the mine, concentrator and sintering plants and in the cold rolling mill exhibited remanent magnetic fields comparable to the referents. There was a relationship between the RMF and the actual urinary chromium concentration. Miners and concentrator and sintering plant workers showed retarded relaxation rate (ReR) of the remanent magnetic field. However, the RMF of the first two of these groups were low (&lt; 0.1 nT) and this made it difficult to measure the ReR accurately. The duration of exposure correlated weakly but significantly with the relaxation rate, while smoking was not related to it.","Estimation of individual dust exposure by magnetopneumography in stainless steel production Abs: The objectives of the study were to measure the magnetic dust lung burden of workers in stainless steel production by magnetopneumography (MPG) and to investigate the relationship of the results with air-borne concentrations of dust, total and hexavalent chromium as well as urinary excretion of chromium. There were 128 workers from the chromite mine, sintering plant, ferrochrome smelter, stainless steel smelting shop, cold rolling mill and welding shop in the exposed groups and five persons from the office staff in the control group. The remanent magnetic field (RMF) in the lungs was slightly elevated among workers in the ferrochromium and steel smelting shops; the levels were, however, lower than those reported for welders earlier and those observed in the welding/repair shop. Workers in the mine, concentrator and sintering plants and in the cold rolling mill exhibited remanent magnetic fields comparable to the referents. There was a relationship between the RMF and the actual urinary chromium concentration. Miners and concentrator and sintering plant workers showed retarded relaxation rate (ReR) of the remanent magnetic field. However, the RMF of the first two of these groups were low (&lt; 0.1 nT) and this made it difficult to measure the ReR accurately. The duration of exposure correlated weakly but significantly with the relaxation rate, while smoking was not related to it."
1233829,Scott et al. 1997,Identification of an accurate soil suspension/dispersion modeling method for use in estimating health-based soil cleanup levels of hexavalent chromium in chromite ore processing residues,"The primary health concern associated with chromite ore processing residues (COPR) at sites in Hudson County, NJ, is the inhalation of Cr(VI) suspended from surface soils. Since health-based soil standards for Cr(VI) will be derived using the inhalation pathway, soil suspension modeling will be necessary to estimate site-specific, health-based soil cleanup levels (HBSCLs). The purpose of this study was to identify the most appropriate particulate emission and air dispersion models for estimating soil suspension at these sites based on their theoretical underpinnings, scientific acceptability, and past performance. The identified modeling approach, the AP-42 particulate emission model and the fugitive dust model (FDM), was used to calculate concentrations of airborne Cr(VI) and TSP at two COPR sites. These estimated concentrations were then compared to concentrations measured at each site. The TSP concentrations calculated using the AP-42/FDM soil suspension modeling approach were all within a factor of 3 of the measured concentrations. The majority of the estimated air concentrations were greater than the measured, indicating that the AP-42/FDM approach tends to overestimate on-site concentrations. The site-specific Cr(VI) HBSCLs for these two sites calculated using this conservative soil suspension modeling approach ranged from 190 to 420 mg/kg.","Identification of an accurate soil suspension/dispersion modeling method for use in estimating health-based soil cleanup levels of hexavalent chromium in chromite ore processing residues Abs: The primary health concern associated with chromite ore processing residues (COPR) at sites in Hudson County, NJ, is the inhalation of Cr(VI) suspended from surface soils. Since health-based soil standards for Cr(VI) will be derived using the inhalation pathway, soil suspension modeling will be necessary to estimate site-specific, health-based soil cleanup levels (HBSCLs). The purpose of this study was to identify the most appropriate particulate emission and air dispersion models for estimating soil suspension at these sites based on their theoretical underpinnings, scientific acceptability, and past performance. The identified modeling approach, the AP-42 particulate emission model and the fugitive dust model (FDM), was used to calculate concentrations of airborne Cr(VI) and TSP at two COPR sites. These estimated concentrations were then compared to concentrations measured at each site. The TSP concentrations calculated using the AP-42/FDM soil suspension modeling approach were all within a factor of 3 of the measured concentrations. The majority of the estimated air concentrations were greater than the measured, indicating that the AP-42/FDM approach tends to overestimate on-site concentrations. The site-specific Cr(VI) HBSCLs for these two sites calculated using this conservative soil suspension modeling approach ranged from 190 to 420 mg/kg."
1233828,Bell and  Hipfner 1997,Airborne hexavalent chromium in southwestern Ontario,"This study reports the first field measurements of airborne hexavalent chromium (Cr(vi)) in southwestern Ontario. Hexavalent chromium was identified as an inhalation carcinogen and an air toxic of concern during the 1991-93 Windsor Air Quality Study. The results of that study indicated that approximately 20% of the routinely monitored ambient airborne chromium (Cr) was in the hexavalent form. In addition, the range of carcinogenic health risks attributable to airborne Cr(vi) was determined to be between 1.4 x 10(-5) and 3.0 x 10(-4) for people living in the Windsor area. During the summer of 1993, analyses of concurrent indoor and outdoor 24-hour air quality samples taken at 33 residences in Hamilton resulted in geometric mean Cr(vi) concentrations of 0.20 ng/m3 and 0.55 ng/m3, respectively, and little or no relationship between the indoor and outdoor sample sets. During the summer of 1994, an airborne Cr(vi) size-fraction study was conducted in Hamilton, the results of which suggested that the majority of the Cr(vi) was in the inhalable fraction.","Airborne hexavalent chromium in southwestern Ontario Abs: This study reports the first field measurements of airborne hexavalent chromium (Cr(vi)) in southwestern Ontario. Hexavalent chromium was identified as an inhalation carcinogen and an air toxic of concern during the 1991-93 Windsor Air Quality Study. The results of that study indicated that approximately 20% of the routinely monitored ambient airborne chromium (Cr) was in the hexavalent form. In addition, the range of carcinogenic health risks attributable to airborne Cr(vi) was determined to be between 1.4 x 10(-5) and 3.0 x 10(-4) for people living in the Windsor area. During the summer of 1993, analyses of concurrent indoor and outdoor 24-hour air quality samples taken at 33 residences in Hamilton resulted in geometric mean Cr(vi) concentrations of 0.20 ng/m3 and 0.55 ng/m3, respectively, and little or no relationship between the indoor and outdoor sample sets. During the summer of 1994, an airborne Cr(vi) size-fraction study was conducted in Hamilton, the results of which suggested that the majority of the Cr(vi) was in the inhalable fraction."
1233827,Mccarty 1997,Subtoxic intracellular trivalent chromium is not mutagenic: implications for safety of chromium supplementation,"For reasons that are outlined, toxicologists have long suspected that intranuclear trivalent chromium mediates much if not all of the well-documented genotoxicity of hexavalent chromium. However, more recent evidence suggests that this genotoxicity is in fact attributable to free radical damage catalyzed by hexavalent chromium under reducing aerobic conditions. Subtoxic intranuclear concentrations of trivalent chromium, while they can be clastogenic in vitro, do not appear to induce point mutations and thus are unlikely to mediate the carcinogenicity of hexavalent compounds. Furthermore, there is considerable doubt that sublethal doses of trivalent chromium can produce tissue levels high enough to induce clastogenic damage in vivo. These considerations elucidate the virtual non-toxicity of orally-administered trivalent chromium in any dose, and strongly suggest that dietary supplementation with trivalent chromium in reasonable amounts is unlikely to carry any genotoxic risk. However, further animal studies are advisable to rule out the possibility of clastogenicity when grossly 'megadose' amounts are ingested.","Subtoxic intracellular trivalent chromium is not mutagenic: implications for safety of chromium supplementation Abs: For reasons that are outlined, toxicologists have long suspected that intranuclear trivalent chromium mediates much if not all of the well-documented genotoxicity of hexavalent chromium. However, more recent evidence suggests that this genotoxicity is in fact attributable to free radical damage catalyzed by hexavalent chromium under reducing aerobic conditions. Subtoxic intranuclear concentrations of trivalent chromium, while they can be clastogenic in vitro, do not appear to induce point mutations and thus are unlikely to mediate the carcinogenicity of hexavalent compounds. Furthermore, there is considerable doubt that sublethal doses of trivalent chromium can produce tissue levels high enough to induce clastogenic damage in vivo. These considerations elucidate the virtual non-toxicity of orally-administered trivalent chromium in any dose, and strongly suggest that dietary supplementation with trivalent chromium in reasonable amounts is unlikely to carry any genotoxic risk. However, further animal studies are advisable to rule out the possibility of clastogenicity when grossly 'megadose' amounts are ingested."
1233825,Edmé et al. 1997,Assessment of biological chromium among stainless steel and mild steel welders in relation to welding processes,"Air and biological monitoring were used for assessing external and internal chromium exposure among 116 stainless steel welders (SS welders) using manual metal arc (MMA), metal inert gas (MIG) and tungsten inert gas (TIG) welding processes (MMA: n = 57; MIG: n = 37; TIG: n = 22) and 30 mild steel welders (MS welders) using MMA and MIG welding processes (MMA: n = 14; MIG: n = 16). The levels of atmospheric total chromium were evaluated after personal air monitoring. The mean values for the different groups of SS welders were 201 micrograms/m3 (MMA) and 185 micrograms/m3 (MIG), 52 micrograms/m3 (TIG) and for MS welders 8.1 micrograms/m3 (MMA) and 7.3 micrograms/m3 (MIG). The curve of cumulative frequency distribution from biological monitoring among SS welders showed chromium geometric mean concentrations in whole blood of 3.6 micrograms/l (95th percentile = 19.9), in plasma of 3.3 micrograms/l (95th percentile = 21.0) and in urine samples of 6.2 micrograms/l (95th percentile = 58.0). Among MS welders, mean values in whole blood and plasma were rather more scattered (1.8 micrograms/l, 95th percentile = 9.3 and 1.3 micrograms/l, 95th percentile = 8.4, respectively) and in urine the value was 2.4 micrograms/l (95th percentile = 13.3). The analysis of variance of chromium concentrations in plasma previously showed a metal effect (F = 29.7, P &lt; 0.001), a process effect (F = 22.2, P &lt; 0.0001) but no metal-process interaction (F = 1.3, P = 0.25). Concerning urinary chromium concentration, the analysis of variance also showed a metal effect (F = 30, P &lt; 0.0001), a process effect (F = 72, P &lt; 0.0001) as well as a metal-process interaction (F = 13.2, P = 0.0004). Throughout the study we noted any significant differences between smokers and non-smokers among welders. Taking in account the relationships between chromium concentrations in whole, plasma or urine and the different welding process. MMA-SS is definitely different from other processes because the biological values are clearly higher. These higher levels are due to the very significant concentrations of total soluble chromium, mainly hexavalent chromium, in welding fumes.","Assessment of biological chromium among stainless steel and mild steel welders in relation to welding processes Abs: Air and biological monitoring were used for assessing external and internal chromium exposure among 116 stainless steel welders (SS welders) using manual metal arc (MMA), metal inert gas (MIG) and tungsten inert gas (TIG) welding processes (MMA: n = 57; MIG: n = 37; TIG: n = 22) and 30 mild steel welders (MS welders) using MMA and MIG welding processes (MMA: n = 14; MIG: n = 16). The levels of atmospheric total chromium were evaluated after personal air monitoring. The mean values for the different groups of SS welders were 201 micrograms/m3 (MMA) and 185 micrograms/m3 (MIG), 52 micrograms/m3 (TIG) and for MS welders 8.1 micrograms/m3 (MMA) and 7.3 micrograms/m3 (MIG). The curve of cumulative frequency distribution from biological monitoring among SS welders showed chromium geometric mean concentrations in whole blood of 3.6 micrograms/l (95th percentile = 19.9), in plasma of 3.3 micrograms/l (95th percentile = 21.0) and in urine samples of 6.2 micrograms/l (95th percentile = 58.0). Among MS welders, mean values in whole blood and plasma were rather more scattered (1.8 micrograms/l, 95th percentile = 9.3 and 1.3 micrograms/l, 95th percentile = 8.4, respectively) and in urine the value was 2.4 micrograms/l (95th percentile = 13.3). The analysis of variance of chromium concentrations in plasma previously showed a metal effect (F = 29.7, P &lt; 0.001), a process effect (F = 22.2, P &lt; 0.0001) but no metal-process interaction (F = 1.3, P = 0.25). Concerning urinary chromium concentration, the analysis of variance also showed a metal effect (F = 30, P &lt; 0.0001), a process effect (F = 72, P &lt; 0.0001) as well as a metal-process interaction (F = 13.2, P = 0.0004). Throughout the study we noted any significant differences between smokers and non-smokers among welders. Taking in account the relationships between chromium concentrations in whole, plasma or urine and the different welding process. MMA-SS is definitely different from other processes because the biological values are clearly higher. These higher levels are due to the very significant concentrations of total soluble chromium, mainly hexavalent chromium, in welding fumes."
1233824,Harzdorf and  Lewalter 1997,Analytical methodology for biological monitoring of chromium,"Analytical aspects associated with biological and ambient monitoring are outlined with an emphasis on processing samples at very low concentrations and optimization of analytical methods. Verification of chromium determination in body fluids by means of &quot;Round Robin&quot; tests is discussed. In addition, an approach for indirect valency discrimination of chromium species relevant in biological monitoring is presented. Application of voltammetry for model tests is described. This is aimed at studying the reaction of hexavalent chromium in human plasma. As a result, a natural reducing capacity of plasma of up to 2 ppm chromium(VI) was detected and quantified as an individual biological index. Furthermore, the effect of ascorbic acid on the reduction of chromium(VI) in plasma is demonstrated and quantitative bases for therapy in cases of accidental intoxication are discussed.","Analytical methodology for biological monitoring of chromium Abs: Analytical aspects associated with biological and ambient monitoring are outlined with an emphasis on processing samples at very low concentrations and optimization of analytical methods. Verification of chromium determination in body fluids by means of &quot;Round Robin&quot; tests is discussed. In addition, an approach for indirect valency discrimination of chromium species relevant in biological monitoring is presented. Application of voltammetry for model tests is described. This is aimed at studying the reaction of hexavalent chromium in human plasma. As a result, a natural reducing capacity of plasma of up to 2 ppm chromium(VI) was detected and quantified as an individual biological index. Furthermore, the effect of ascorbic acid on the reduction of chromium(VI) in plasma is demonstrated and quantitative bases for therapy in cases of accidental intoxication are discussed."
1233823,Cross et al. 1997,Establishing an occupational exposure limit for hexavalent chromium in the European Union,"A Criteria Document for hexavalent chromium [Cr(VI)], currently under preparation at the Institute of Occupational Health, University of Birmingham, is intended for use in setting an occupational exposure limit (OEL) for Cr(VI) in the European Union (EU). The requirement for establishing OELs, specifically known as indicative limit values, in the EU is set out in Council Directive 80/1107/EEC, amended by Council Directive 88/642/EEC. To facilitate this procedure the Commission has set up a Scientific Committee for Occupational Exposure Limits to Chemical Agents. The Committee, which is composed of independent scientific experts from member states, is responsible for reviewing available scientific data. A Criteria Document forms the basis of the scientific data considered during this process and contains an up-to-date, critical evaluation of available information which is relevant to setting an exposure limit. After consideration of the scientific data for a particular substance, the Committee advises the Commission on setting a health-based OEL. Consideration of other questions such as technical matters and socioeconomic issues occurs during later stages of the procedure, before an OEL is finally adopted. The procedure allows for consultation with interested parties. The Criteria Document for Cr(VI) contains sections on substance identification, chemical and physical properties, production and use data, recent data on occupational exposure, current methods for measurement and analysis, and toxicology. The toxicology section contains a critical evaluation of both human and animal data and forms a major part of the document. This section enables identification of critical health effects associated with exposure to Cr(VI) and consideration of dose-response relationships and provides the basis for any risk assessment and recommendation for an OEL.","Establishing an occupational exposure limit for hexavalent chromium in the European Union Abs: A Criteria Document for hexavalent chromium [Cr(VI)], currently under preparation at the Institute of Occupational Health, University of Birmingham, is intended for use in setting an occupational exposure limit (OEL) for Cr(VI) in the European Union (EU). The requirement for establishing OELs, specifically known as indicative limit values, in the EU is set out in Council Directive 80/1107/EEC, amended by Council Directive 88/642/EEC. To facilitate this procedure the Commission has set up a Scientific Committee for Occupational Exposure Limits to Chemical Agents. The Committee, which is composed of independent scientific experts from member states, is responsible for reviewing available scientific data. A Criteria Document forms the basis of the scientific data considered during this process and contains an up-to-date, critical evaluation of available information which is relevant to setting an exposure limit. After consideration of the scientific data for a particular substance, the Committee advises the Commission on setting a health-based OEL. Consideration of other questions such as technical matters and socioeconomic issues occurs during later stages of the procedure, before an OEL is finally adopted. The procedure allows for consultation with interested parties. The Criteria Document for Cr(VI) contains sections on substance identification, chemical and physical properties, production and use data, recent data on occupational exposure, current methods for measurement and analysis, and toxicology. The toxicology section contains a critical evaluation of both human and animal data and forms a major part of the document. This section enables identification of critical health effects associated with exposure to Cr(VI) and consideration of dose-response relationships and provides the basis for any risk assessment and recommendation for an OEL."
1233822,Wang et al. 1997,Determination of hexavalent chromium in industrial hygiene samples using ultrasonic extraction and flow injection analysis,"A simple, fast, and sensitive method was developed for the determination of hexavalent chromium (CrVI) in workplace samples. Ultrasonic extraction in alkaline solutions with 0.05 M (NH4)2SO4-0.05 M NH3 provided good extraction efficiency of CrVI from the sample and allowed the retention of CrVI on an ion-exchange resin (95%). The CrVI in the sample solution was then separated as an anion from trivalent chromium [CrIII] and other cations by elution from the anion-exchange resin with 0.5 M (NH4)2SO4 in 0.1 M NH3 (pH 8) buffer solution. The eluate was then acidified with hydrochloric acid and complexed with 1,5-diphenylcarbazide reagent prior to flow injection analysis. By analyzing samples with and without oxidation of CrIII to CrVI using CeIV, the method can measure CrVI and total Cr. For optimizing the separation and determination procedure, preliminary trials conducted with two certified reference materials (CRMs 013-050 and NIST 1633a) and three spiked samples (ammonia buffer solution, cellulose ester filters and acid washed sand) indicated that the recovery of CrVI was quantitative (&gt; 90%) with this method. The limit of detection for FIA-UV/VIS determination of the Cr-diphenylcarbazone complex was in the sub-nanogram range (0.11 ng). The technique was also applied successfully to a workplace coal fly ash sample that was collected from a power plant and paint chips that were collected from a heating gas pipe and a university building. The principal advantages of this method are its simplicity, sensitivity, speed and potential portability for field analysis.","Determination of hexavalent chromium in industrial hygiene samples using ultrasonic extraction and flow injection analysis Abs: A simple, fast, and sensitive method was developed for the determination of hexavalent chromium (CrVI) in workplace samples. Ultrasonic extraction in alkaline solutions with 0.05 M (NH4)2SO4-0.05 M NH3 provided good extraction efficiency of CrVI from the sample and allowed the retention of CrVI on an ion-exchange resin (95%). The CrVI in the sample solution was then separated as an anion from trivalent chromium [CrIII] and other cations by elution from the anion-exchange resin with 0.5 M (NH4)2SO4 in 0.1 M NH3 (pH 8) buffer solution. The eluate was then acidified with hydrochloric acid and complexed with 1,5-diphenylcarbazide reagent prior to flow injection analysis. By analyzing samples with and without oxidation of CrIII to CrVI using CeIV, the method can measure CrVI and total Cr. For optimizing the separation and determination procedure, preliminary trials conducted with two certified reference materials (CRMs 013-050 and NIST 1633a) and three spiked samples (ammonia buffer solution, cellulose ester filters and acid washed sand) indicated that the recovery of CrVI was quantitative (&gt; 90%) with this method. The limit of detection for FIA-UV/VIS determination of the Cr-diphenylcarbazone complex was in the sub-nanogram range (0.11 ng). The technique was also applied successfully to a workplace coal fly ash sample that was collected from a power plant and paint chips that were collected from a heating gas pipe and a university building. The principal advantages of this method are its simplicity, sensitivity, speed and potential portability for field analysis."
1233821,Turick et al. 1997,Reduction of Cr(6+) to Cr(3 +) in a packed-bed bioreactor,"Hexavalent chromium, Cr(6+), is a common and toxic pollutant in soils and waters. Reduction of the mobile Cr(6+) to the less mobile and less toxic trivalent chromium, Cr(3+), can be achieved with conventional chemical reduction technologies. Alternatively, Cr(6+) can be biochemically reduced to Cr(3+) by anaerobic microbial consortia which appear to use Cr(6+) as a terminal electron acceptor. A bioprocess for Cr(6+) reduction has been demonstrated using a packed-bed bioreactor containing ceramic packing, and then compared to a similar bioreactor containing DuPont Bio-Sep beads. An increase in volumetric productivity (from 4 mg Cr(6+)/L/h to 260 mg Cr(6+)/L/h, probably due to an increase in biomass density, was obtained using Bio-Sep beads. The beads contain internal macropores which were shown by scanning electron microscopy to house dense concentrations of bacteria. Comparisons to conventional Cr(6+) treatment technologies indicate that a bioprocess has several economic and operational advantages.","Reduction of Cr(6+) to Cr(3 +) in a packed-bed bioreactor Abs: Hexavalent chromium, Cr(6+), is a common and toxic pollutant in soils and waters. Reduction of the mobile Cr(6+) to the less mobile and less toxic trivalent chromium, Cr(3+), can be achieved with conventional chemical reduction technologies. Alternatively, Cr(6+) can be biochemically reduced to Cr(3+) by anaerobic microbial consortia which appear to use Cr(6+) as a terminal electron acceptor. A bioprocess for Cr(6+) reduction has been demonstrated using a packed-bed bioreactor containing ceramic packing, and then compared to a similar bioreactor containing DuPont Bio-Sep beads. An increase in volumetric productivity (from 4 mg Cr(6+)/L/h to 260 mg Cr(6+)/L/h, probably due to an increase in biomass density, was obtained using Bio-Sep beads. The beads contain internal macropores which were shown by scanning electron microscopy to house dense concentrations of bacteria. Comparisons to conventional Cr(6+) treatment technologies indicate that a bioprocess has several economic and operational advantages."
1233820,Itoh and  Shimada 1998,Bone marrow and liver mutagenesis in lacZ transgenic mice treated with hexavalent chromium,"The mutagenic effects of the hexavalent chromium compound K2CrO4 in lacZ transgenic mice (Muta Mouse) were investigated at two sampling times. K2CrO4 was administered intraperitoneally to five male mice per treatment group at a single dose of 40 mg/kg. The animals were sacrificed on days 1 and 7 after the treatment. Mutant frequencies in the bone marrow and liver were analyzed by the positive selection method using Escherichia coli C (galE-) strain and phenyl beta-D-galactoside. K2CrO4 induced a significant increase in mutant frequency in the bone marrow on day 1, but not on day 7 after the treatment. In the liver, on the other hand, a significant induction in the mutant frequency was seen on day 7, whereas no induction was observed on day 1. The reason for the different responses to the mutagenic activity of K2CrO4 between these organs may be related to their cell turnover rates. The mutations induced by K2CrO4 in the bone marrow may have occurred in more differentiated cells than stem cells, and the rapid proliferative activity may have caused a rapid decrease in mutated cells by day 7. These results suggest that experiments on mutagenesis should be done with more than one sampling point, a short expression time in addition to a longer one, so as to detect mutations induced in organ with high cell proliferation.","Bone marrow and liver mutagenesis in lacZ transgenic mice treated with hexavalent chromium Abs: The mutagenic effects of the hexavalent chromium compound K2CrO4 in lacZ transgenic mice (Muta Mouse) were investigated at two sampling times. K2CrO4 was administered intraperitoneally to five male mice per treatment group at a single dose of 40 mg/kg. The animals were sacrificed on days 1 and 7 after the treatment. Mutant frequencies in the bone marrow and liver were analyzed by the positive selection method using Escherichia coli C (galE-) strain and phenyl beta-D-galactoside. K2CrO4 induced a significant increase in mutant frequency in the bone marrow on day 1, but not on day 7 after the treatment. In the liver, on the other hand, a significant induction in the mutant frequency was seen on day 7, whereas no induction was observed on day 1. The reason for the different responses to the mutagenic activity of K2CrO4 between these organs may be related to their cell turnover rates. The mutations induced by K2CrO4 in the bone marrow may have occurred in more differentiated cells than stem cells, and the rapid proliferative activity may have caused a rapid decrease in mutated cells by day 7. These results suggest that experiments on mutagenesis should be done with more than one sampling point, a short expression time in addition to a longer one, so as to detect mutations induced in organ with high cell proliferation."
1233819,Shimada et al. 1998,Cadmium suppresses apoptosis induced by chromium,"Cadmium and chromium are both well-known human carcinogens, and common exposures to these metals are not infrequent. Recent studies have shown that hexavalent chromium induces apoptosis in Chinese hamster ovary (CHO) cells, suggesting an association of apoptosis with carcinogenesis. In contrast, induction of apoptosis by cadmium has been inconsistently observed. The present study was designed to determine if cadmium could induce apoptosis in CHO cells and if common exposure to cadmium and chromium would modify any apoptotic response. Apoptosis was evaluated by both agarose gel and in situ end-labeling methods. Apoptosis was observed at 48 h after treatment with 300 microM chromium (Na2CrO4) for 2 h. Cadmium alone at concentrations of 1, 5, or 10 microM (as CdCl2) did not induce apoptosis in these cells even at times up to 72 h after treatment. However, when CHO cells were concurrently exposed to cadmium and chromium, chromium-induced apoptosis was markedly suppressed in a cadmium concentration-related fashion. Cadmium did not consistently modify the cytotoxic effects of chromium, and significant increases in metallothionein were not induced by these metal treatments. These findings indicate that cadmium can block chromium-induced apoptosis. The suppression of apoptosis by cadmium may be a significant aspect of its carcinogenic mechanism.","Cadmium suppresses apoptosis induced by chromium Abs: Cadmium and chromium are both well-known human carcinogens, and common exposures to these metals are not infrequent. Recent studies have shown that hexavalent chromium induces apoptosis in Chinese hamster ovary (CHO) cells, suggesting an association of apoptosis with carcinogenesis. In contrast, induction of apoptosis by cadmium has been inconsistently observed. The present study was designed to determine if cadmium could induce apoptosis in CHO cells and if common exposure to cadmium and chromium would modify any apoptotic response. Apoptosis was evaluated by both agarose gel and in situ end-labeling methods. Apoptosis was observed at 48 h after treatment with 300 microM chromium (Na2CrO4) for 2 h. Cadmium alone at concentrations of 1, 5, or 10 microM (as CdCl2) did not induce apoptosis in these cells even at times up to 72 h after treatment. However, when CHO cells were concurrently exposed to cadmium and chromium, chromium-induced apoptosis was markedly suppressed in a cadmium concentration-related fashion. Cadmium did not consistently modify the cytotoxic effects of chromium, and significant increases in metallothionein were not induced by these metal treatments. These findings indicate that cadmium can block chromium-induced apoptosis. The suppression of apoptosis by cadmium may be a significant aspect of its carcinogenic mechanism."
1233818,Singh and  Snow 1998,Chromium(III) decreases the fidelity of human DNA polymerase beta,"Certain particulate compounds of hexavalent chromium are well-known occupational and environmental human carcinogens. Hexavalent chromium primarily enters the cells and undergoes metabolic reduction; however, the ultimate trivalent oxidation state of chromium, Cr(III), predominates within the cell. DNA-bound Cr(III) has been previously shown to decrease the fidelity of replication in the M13 phage mutation assay. This study was done to understand how Cr(III), in the presence of physiological concentrations of magnesium, affects the kinetic parameters of steady-state DNA synthesis in vitro across site-specific O6-methylguanine (m6dG) residues by DNA polymerase beta (pol beta). Cr(III) binds to the short oligomer templates in a dose-dependent manner and stimulates the activity of pol beta. Cr(III) stimulates the mutagenic incorporation of dTTP opposite m6dG more than the nonmutagenic incorporation of dCTP, and thereby Cr(III) further decreases the fidelity of DNA synthesis across m6dG by pol beta. In contrast, Cr(III) does not affect the fidelity of DNA synthesis across the normal template base, dG. Both the enhanced activity and the mutagenic lesion bypass in the presence of Cr(III) may be associated with Cr(III)-dependent stimulation of pol beta binding to DNA as reported here. This study shows some of the mechanisms by which mutagenic chromium affects DNA synthesis.","Chromium(III) decreases the fidelity of human DNA polymerase beta Abs: Certain particulate compounds of hexavalent chromium are well-known occupational and environmental human carcinogens. Hexavalent chromium primarily enters the cells and undergoes metabolic reduction; however, the ultimate trivalent oxidation state of chromium, Cr(III), predominates within the cell. DNA-bound Cr(III) has been previously shown to decrease the fidelity of replication in the M13 phage mutation assay. This study was done to understand how Cr(III), in the presence of physiological concentrations of magnesium, affects the kinetic parameters of steady-state DNA synthesis in vitro across site-specific O6-methylguanine (m6dG) residues by DNA polymerase beta (pol beta). Cr(III) binds to the short oligomer templates in a dose-dependent manner and stimulates the activity of pol beta. Cr(III) stimulates the mutagenic incorporation of dTTP opposite m6dG more than the nonmutagenic incorporation of dCTP, and thereby Cr(III) further decreases the fidelity of DNA synthesis across m6dG by pol beta. In contrast, Cr(III) does not affect the fidelity of DNA synthesis across the normal template base, dG. Both the enhanced activity and the mutagenic lesion bypass in the presence of Cr(III) may be associated with Cr(III)-dependent stimulation of pol beta binding to DNA as reported here. This study shows some of the mechanisms by which mutagenic chromium affects DNA synthesis."
1233816,Asmatullah et al. 1998,Hexavalent chromium-induced congenital abnormalities in chick embryos,"The embryotoxic and teratogenic potential of hexavalent chromium was evaluated in chick embryos. Different concentrations of aqueous solution of potassium dichromate ranging from 1.00 to 100.00 microg per egg were injected into chick eggs before incubation. A dose-dependent embryonic mortality was observed in all the groups examined on days 7 and 14 of incubation. The following malformations were observed in survivors: reduced body size and organs; microphthalmia; micromelia; everted viscera; abnormal and twisted neck, beak and spinal cord; isolated epicarditis; club foot; haemorrhage; and patchy feathers. Total mortality showing embryonic resorption was noted in higher dose groups (25-100 microg per egg) on day 14 of incubation.","Hexavalent chromium-induced congenital abnormalities in chick embryos Abs: The embryotoxic and teratogenic potential of hexavalent chromium was evaluated in chick embryos. Different concentrations of aqueous solution of potassium dichromate ranging from 1.00 to 100.00 microg per egg were injected into chick eggs before incubation. A dose-dependent embryonic mortality was observed in all the groups examined on days 7 and 14 of incubation. The following malformations were observed in survivors: reduced body size and organs; microphthalmia; micromelia; everted viscera; abnormal and twisted neck, beak and spinal cord; isolated epicarditis; club foot; haemorrhage; and patchy feathers. Total mortality showing embryonic resorption was noted in higher dose groups (25-100 microg per egg) on day 14 of incubation."
1233815,Sridevi et al. 1998,"Effect of trivalent and hexavalent chromium on antioxidant enzyme activities and lipid peroxidation in a freshwater field crab, Barytelphusa guerini",,"Effect of trivalent and hexavalent chromium on antioxidant enzyme activities and lipid peroxidation in a freshwater field crab, Barytelphusa guerini Abs: "
1233814,Kanojia et al. 1998,Embryo and fetotoxicity of hexavalent chromium: a long-term study,"Ingestion of chromium(VI) (250, 500 or 750 ppm as potassium dichromate, K2Cr2O7) through drinking water by female rats for 3 months prior to gestation was toxic to embryo and fetus. There was a significant reduction in number of implantations and number of fetuses and an increase in number of resorptions and pre-implantation and post-implantation losses. No significant visceral abnormality was found. The increase in the number of subdermal hemorrhagic patches on the thorax and abdomen was significant. Skeletal abnormality in the form of reduced ossification in parietal, interparietal and caudal bones was observed in fetuses. Chromium levels in the blood of mothers, placenta and fetuses showed a significant increase. Duration of the estrous cycle was also increased significantly. The study revealed that long-term chromium exposure in rats did not cause embryo and fetotoxicity in a duration-dependent manner compared to short-term treatment as observed earlier. A possible explanation could be that, in the 90-day study, the female rats did not mate for three estrous cycles, thus giving time for clearance of a sizable amount of chromium from their bodies.","Embryo and fetotoxicity of hexavalent chromium: a long-term study Abs: Ingestion of chromium(VI) (250, 500 or 750 ppm as potassium dichromate, K2Cr2O7) through drinking water by female rats for 3 months prior to gestation was toxic to embryo and fetus. There was a significant reduction in number of implantations and number of fetuses and an increase in number of resorptions and pre-implantation and post-implantation losses. No significant visceral abnormality was found. The increase in the number of subdermal hemorrhagic patches on the thorax and abdomen was significant. Skeletal abnormality in the form of reduced ossification in parietal, interparietal and caudal bones was observed in fetuses. Chromium levels in the blood of mothers, placenta and fetuses showed a significant increase. Duration of the estrous cycle was also increased significantly. The study revealed that long-term chromium exposure in rats did not cause embryo and fetotoxicity in a duration-dependent manner compared to short-term treatment as observed earlier. A possible explanation could be that, in the 90-day study, the female rats did not mate for three estrous cycles, thus giving time for clearance of a sizable amount of chromium from their bodies."
1233813,Garbisu et al. 1998,Aerobic chromate reduction by Bacillus subtilis,"We have studied the reduction of hexavalent chromium (chromate) to the less toxic trivalent form by using cell suspensions and cell-free extracts from the common soil bacterium, Bacillus subtilis. B. subtilis was able to grow and reduce chromate at concentrations ranging from 0.1 to 1 mM K2CrO4. Chromate reduction was not affected by a 20-fold excess of nitrate-compound that serves as alternate electron acceptor and antagonizes chromate reduction by anaerobic bacteria. Metabolic poisons including sodium azide and sodium cyanide inhibited chromate reduction. Reduction was effected by a constitutive system associated with the soluble protein fraction and not with the membrane fraction. The reducing activity was heat labile and showed a Km of 188 microns CrO4(2)-. The reductase can mediate the transfer of electrons from NAD(P)H to chromate. The results suggest that chromate is reduced via a detoxification system rather than dissimilatory electron transport.","Aerobic chromate reduction by Bacillus subtilis Abs: We have studied the reduction of hexavalent chromium (chromate) to the less toxic trivalent form by using cell suspensions and cell-free extracts from the common soil bacterium, Bacillus subtilis. B. subtilis was able to grow and reduce chromate at concentrations ranging from 0.1 to 1 mM K2CrO4. Chromate reduction was not affected by a 20-fold excess of nitrate-compound that serves as alternate electron acceptor and antagonizes chromate reduction by anaerobic bacteria. Metabolic poisons including sodium azide and sodium cyanide inhibited chromate reduction. Reduction was effected by a constitutive system associated with the soluble protein fraction and not with the membrane fraction. The reducing activity was heat labile and showed a Km of 188 microns CrO4(2)-. The reductase can mediate the transfer of electrons from NAD(P)H to chromate. The results suggest that chromate is reduced via a detoxification system rather than dissimilatory electron transport."
1233812,Singh et al. 1998,Differential sensitivity of chromium-mediated DNA interstrand crosslinks and DNA-protein crosslinks to disruption by alkali and EDTA,"Some compounds of hexavalent chromium are well-established carcinogens. Chromium enters mammalian cells in the hexavalent form and is reduced to chromium (III). Treatment of purified DNA with chromium (III) produces DNA-DNA interstrand crosslinks (DDC) which obstruct the progression of DNA polymerases in vitro. DDC were also detected in chromate-treated cultured normal human lung cells using the renaturing agarose gel electrophoresis (RAGE) assay and correlated with base-specific inhibition of DNA replication. Curiously, DDC have gone undetected in studies of cultured cells using the alkaline elution (AE) technique, whereas chromium-mediated DNA-protein crosslinks (DPC) were readily detected by AE. We tested the hypothesis that AE conditions [60 mM tetraethyl ammonium hydroxide (TEA), 20 mM EDTA, pH 12.6, for 16 h at room temperature] dissociate DDC but not DPC using chromium(III)-treated plasmid DNA and the RAGE assay. Dose-dependent chromium-induced DDC were unaffected by TEA (pH 11.8) alone or by more rigorous alkaline denaturation conditions (200 mM NaOH, pH 13.5, for 16 h). DDC were, however, completely disrupted by EDTA (pH 12.6) alone or the combination of TEA and EDTA (pH 12.6). In contrast, DPC remained largely intact under these conditions. Therefore, past AE-based studies which have failed to detect chromium-induced DDC do not prove the absence of this lesion. AE may not be suitable for detecting DDC induced by EDTA-chelatable agents such as metals.","Differential sensitivity of chromium-mediated DNA interstrand crosslinks and DNA-protein crosslinks to disruption by alkali and EDTA Abs: Some compounds of hexavalent chromium are well-established carcinogens. Chromium enters mammalian cells in the hexavalent form and is reduced to chromium (III). Treatment of purified DNA with chromium (III) produces DNA-DNA interstrand crosslinks (DDC) which obstruct the progression of DNA polymerases in vitro. DDC were also detected in chromate-treated cultured normal human lung cells using the renaturing agarose gel electrophoresis (RAGE) assay and correlated with base-specific inhibition of DNA replication. Curiously, DDC have gone undetected in studies of cultured cells using the alkaline elution (AE) technique, whereas chromium-mediated DNA-protein crosslinks (DPC) were readily detected by AE. We tested the hypothesis that AE conditions [60 mM tetraethyl ammonium hydroxide (TEA), 20 mM EDTA, pH 12.6, for 16 h at room temperature] dissociate DDC but not DPC using chromium(III)-treated plasmid DNA and the RAGE assay. Dose-dependent chromium-induced DDC were unaffected by TEA (pH 11.8) alone or by more rigorous alkaline denaturation conditions (200 mM NaOH, pH 13.5, for 16 h). DDC were, however, completely disrupted by EDTA (pH 12.6) alone or the combination of TEA and EDTA (pH 12.6). In contrast, DPC remained largely intact under these conditions. Therefore, past AE-based studies which have failed to detect chromium-induced DDC do not prove the absence of this lesion. AE may not be suitable for detecting DDC induced by EDTA-chelatable agents such as metals."
1233811,Dartsch et al. 1998,Investigations on the nephrotoxicity and hepatotoxicity of trivalent and hexavalent chromium compounds,"In contrast to trivalent chromium (Cr(III)) compounds, hexavalent chromium ((Cr(VI)) compounds are oxidizing agents capable of directly inducing tissue damage and possessing carcinogenic, mutagenic and teratogenic potency. After oral or dermal absorption of Cr(VI), the kidney is the main target organ for chromium accumulation, which might result in acute tubular necrosis in humans. In contrast, an acute toxic effect of Cr(VI) on the liver has not yet been described. Therefore, we used two established epithelial cell lines from the kidney (Opossum kidney cells) and the liver (Hep G2 cells) to design an in vitro-assay which is able to examine acute toxic effects of chromium compounds. Cells of both cell lines were treated with various concentrations of Cr(III) and Cr(VI) ranging from 0.01 micromol/l to 1 mmol/l for 24 h. Thereafter, cell morphology, organization of the intracellular cytoskeleton, number of viable cells and mean cell volume were examined. The results show that Cr(VI), but not Cr(III), has an acute cytotoxic effect and causes a dose-dependent loss in cell viability. The effective dose that caused 50% of cell death was 5 micromol/l for kidney epithelial cells and 50 micromol/l for liver epithelial cells. This means that kidney epithelial cells are 10 times more sensitive towards Cr(VI) treatment than liver epithelial cells and this might explain the known nephrotoxicity in vivo. The loss in cell viability was accompanied by a rounding and detachment of the cells and a marked reduction of intracellular F-actin-containing stress fibers. Microtubules and intermediate-sized filaments were observed to be unaffected. Only in the case of kidney epithelial cells, a dose-dependent cell volume increase was observed after Cr(VI) treatment at concentrations up to 50 micromol/l. At higher concentrations, the cell volume decreased due to the high number of cells undergoing lysis and the appearance of cellular fragments. Various chloride channel blockers with different specificities, molecular structures and inhibitory potentials were tested for their ability to prevent Cr(VI)-induced cell damage. None of the channel blockers was able to inhibit cell damage, suggesting that the uptake of Cr(VI) through the general anion transport system of the cell membrane might be only one facet of cellular uptake and toxification. The data presented here not only confirm the different organ-specific effects of Cr(III) and Cr(VI), but also provide a basis for future experiments on the understanding of acute toxicity of Cr(VI) compounds. Moreover, the results demonstrate that the designed in vitro-assay might be a useful tool to prove whether non-toxic Cr(III) can be oxidized to Cr(VI) under specific industrial conditions (for example, in the leather or chrome industry).","Investigations on the nephrotoxicity and hepatotoxicity of trivalent and hexavalent chromium compounds Abs: In contrast to trivalent chromium (Cr(III)) compounds, hexavalent chromium ((Cr(VI)) compounds are oxidizing agents capable of directly inducing tissue damage and possessing carcinogenic, mutagenic and teratogenic potency. After oral or dermal absorption of Cr(VI), the kidney is the main target organ for chromium accumulation, which might result in acute tubular necrosis in humans. In contrast, an acute toxic effect of Cr(VI) on the liver has not yet been described. Therefore, we used two established epithelial cell lines from the kidney (Opossum kidney cells) and the liver (Hep G2 cells) to design an in vitro-assay which is able to examine acute toxic effects of chromium compounds. Cells of both cell lines were treated with various concentrations of Cr(III) and Cr(VI) ranging from 0.01 micromol/l to 1 mmol/l for 24 h. Thereafter, cell morphology, organization of the intracellular cytoskeleton, number of viable cells and mean cell volume were examined. The results show that Cr(VI), but not Cr(III), has an acute cytotoxic effect and causes a dose-dependent loss in cell viability. The effective dose that caused 50% of cell death was 5 micromol/l for kidney epithelial cells and 50 micromol/l for liver epithelial cells. This means that kidney epithelial cells are 10 times more sensitive towards Cr(VI) treatment than liver epithelial cells and this might explain the known nephrotoxicity in vivo. The loss in cell viability was accompanied by a rounding and detachment of the cells and a marked reduction of intracellular F-actin-containing stress fibers. Microtubules and intermediate-sized filaments were observed to be unaffected. Only in the case of kidney epithelial cells, a dose-dependent cell volume increase was observed after Cr(VI) treatment at concentrations up to 50 micromol/l. At higher concentrations, the cell volume decreased due to the high number of cells undergoing lysis and the appearance of cellular fragments. Various chloride channel blockers with different specificities, molecular structures and inhibitory potentials were tested for their ability to prevent Cr(VI)-induced cell damage. None of the channel blockers was able to inhibit cell damage, suggesting that the uptake of Cr(VI) through the general anion transport system of the cell membrane might be only one facet of cellular uptake and toxification. The data presented here not only confirm the different organ-specific effects of Cr(III) and Cr(VI), but also provide a basis for future experiments on the understanding of acute toxicity of Cr(VI) compounds. Moreover, the results demonstrate that the designed in vitro-assay might be a useful tool to prove whether non-toxic Cr(III) can be oxidized to Cr(VI) under specific industrial conditions (for example, in the leather or chrome industry)."
1233810,Lameiras et al. 1998,Quantification of total chromium and hexavalent chromium in UHT milk by ETAAS,"Procedures for the quantification of total chromium and hexavalent chromium in UHT milk samples are presented. Total chromium was determined directly in milk with the addition of a surfactant and a mixture of Pd and Mg as a chemical modifier. For the selective separation of hexavalent chromium, the sample pre-treatment consisted in precipitation of proteins and elution of the supernatant through a Chromabond NH2 column. The metal was eluted with nitric acid. Both total chromium and hexavalent chromium were evaluated by atomic absorption spectrometry with electrothermal atomization using the same instrumental conditions. The detection limits were 0.2 and 0.15 microgram l-1 for total chromium and hexavalent chromium, respectively. The linearity ranges under the optimized conditions were 0.2-20 and 0.15-50 micrograms l-1. For total chromium the precision was 4.9 and 5.7% for the analytical and the over-all procedure, respectively, and for hexavalent chromium 4.3 and 4.9%, respectively. The validation of both procedures was performed by the standard additions method and the recoveries were higher than 93% in all cases. For total chromium, a certified reference material was also used to validate the methodology. The methods were applied to the determination of total chromium and hexavalent chromium in 60 UHT milk samples.","Quantification of total chromium and hexavalent chromium in UHT milk by ETAAS Abs: Procedures for the quantification of total chromium and hexavalent chromium in UHT milk samples are presented. Total chromium was determined directly in milk with the addition of a surfactant and a mixture of Pd and Mg as a chemical modifier. For the selective separation of hexavalent chromium, the sample pre-treatment consisted in precipitation of proteins and elution of the supernatant through a Chromabond NH2 column. The metal was eluted with nitric acid. Both total chromium and hexavalent chromium were evaluated by atomic absorption spectrometry with electrothermal atomization using the same instrumental conditions. The detection limits were 0.2 and 0.15 microgram l-1 for total chromium and hexavalent chromium, respectively. The linearity ranges under the optimized conditions were 0.2-20 and 0.15-50 micrograms l-1. For total chromium the precision was 4.9 and 5.7% for the analytical and the over-all procedure, respectively, and for hexavalent chromium 4.3 and 4.9%, respectively. The validation of both procedures was performed by the standard additions method and the recoveries were higher than 93% in all cases. For total chromium, a certified reference material was also used to validate the methodology. The methods were applied to the determination of total chromium and hexavalent chromium in 60 UHT milk samples."
1233809,Niemelä et al. 1998,Target levels--tools for prevention,"Although occupational exposure limits are sought to establish health-based standards, they do not always give a sufficient basis for planning an indoor air climate that is good and comfortable for the occupants in industrial work rooms. This paper considers methodologies by which the desired level, i.e., target level, of air quality in industrial settings can be defined, taking into account feasibility issues. Risk assessment based on health criteria is compared with risk-assessment based on &quot;Best Available Technology&quot; (BAT). Because health-based risk estimates at low concentration regions are rather inaccurate, the technology-based approach is emphasized. The technological approach is based on information on the prevailing concentrations in industrial work environments and the benchmark air quality attained with the best achievable technology. The prevailing contaminant concentrations are obtained from a contaminant exposure databank, and the benchmark air quality by field measurements in industrial work rooms equipped with advanced ventilation and production technology. As an example, the target level assessment has been applied to formaldehyde, total inorganic dust and hexavalent chromium, which are common contaminants in work room air.","Target levels--tools for prevention Abs: Although occupational exposure limits are sought to establish health-based standards, they do not always give a sufficient basis for planning an indoor air climate that is good and comfortable for the occupants in industrial work rooms. This paper considers methodologies by which the desired level, i.e., target level, of air quality in industrial settings can be defined, taking into account feasibility issues. Risk assessment based on health criteria is compared with risk-assessment based on &quot;Best Available Technology&quot; (BAT). Because health-based risk estimates at low concentration regions are rather inaccurate, the technology-based approach is emphasized. The technological approach is based on information on the prevailing concentrations in industrial work environments and the benchmark air quality attained with the best achievable technology. The prevailing contaminant concentrations are obtained from a contaminant exposure databank, and the benchmark air quality by field measurements in industrial work rooms equipped with advanced ventilation and production technology. As an example, the target level assessment has been applied to formaldehyde, total inorganic dust and hexavalent chromium, which are common contaminants in work room air."
1233808,Shumilla et al. 1999,Chromium(VI) inhibits the transcriptional activity of nuclear factor-kappaB by decreasing the interaction of p65 with cAMP-responsive element-binding protein-binding protein,"Chromium(VI) regulation of gene expression has been attributed to the generation of reactive chromium and oxygen species, DNA damage, and alterations in mRNA stability. However, the effects of Cr(VI) on signal transduction leading to gene expression are not resolved. Therefore, this study investigated the effects of Cr(VI) on basal and tumor necrosis factor-alpha (TNF-alpha)-induced transcriptional competence of nuclear factor-kappaB (NF-kappaB) in A549 human lung carcinoma cells. Pretreatment of A549 cells with nontoxic levels of Cr(VI) inhibited TNF-alpha-stimulated expression of the endogenous gene for interleukin-8 and of an NF-kappaB-driven luciferase gene construct, but not expression of urokinase, a gene with a more complex promoter. Chromium did not inhibit TNF-alpha-stimulated IkappaBalpha degradation or translocation of NF-kappaB-binding proteins to the nucleus. However, Cr(VI) pretreatments prevented TNF-alpha-stimulated interactions between the p65 subunit of NF-kappaB and the transcriptional cofactor cAMP-responsive element-binding protein-binding protein (CBP). This inhibition was not the result of an effect of chromium on the protein kinase A catalytic activity required for p65/CBP interactions. In contrast, Cr(VI) caused concentration-dependent increases in c-Jun/CBP interactions. These data indicate that nontoxic levels of hexavalent chromium selectively inhibit NF-kappaB transcriptional competence by inhibiting interactions with coactivators of transcription rather than DNA binding.","Chromium(VI) inhibits the transcriptional activity of nuclear factor-kappaB by decreasing the interaction of p65 with cAMP-responsive element-binding protein-binding protein Abs: Chromium(VI) regulation of gene expression has been attributed to the generation of reactive chromium and oxygen species, DNA damage, and alterations in mRNA stability. However, the effects of Cr(VI) on signal transduction leading to gene expression are not resolved. Therefore, this study investigated the effects of Cr(VI) on basal and tumor necrosis factor-alpha (TNF-alpha)-induced transcriptional competence of nuclear factor-kappaB (NF-kappaB) in A549 human lung carcinoma cells. Pretreatment of A549 cells with nontoxic levels of Cr(VI) inhibited TNF-alpha-stimulated expression of the endogenous gene for interleukin-8 and of an NF-kappaB-driven luciferase gene construct, but not expression of urokinase, a gene with a more complex promoter. Chromium did not inhibit TNF-alpha-stimulated IkappaBalpha degradation or translocation of NF-kappaB-binding proteins to the nucleus. However, Cr(VI) pretreatments prevented TNF-alpha-stimulated interactions between the p65 subunit of NF-kappaB and the transcriptional cofactor cAMP-responsive element-binding protein-binding protein (CBP). This inhibition was not the result of an effect of chromium on the protein kinase A catalytic activity required for p65/CBP interactions. In contrast, Cr(VI) caused concentration-dependent increases in c-Jun/CBP interactions. These data indicate that nontoxic levels of hexavalent chromium selectively inhibit NF-kappaB transcriptional competence by inhibiting interactions with coactivators of transcription rather than DNA binding."
1233806,B?asiak et al. 1999,DNA damage and repair in human lymphocytes and gastric mucosa cells exposed to chromium and curcumin,"Human population can be considered as a subject of combined exposure to chemicals. Hexavalent chromium is a well-known mutagen and carcinogen. Curcumin, a popular spice and pigment, is reported to have antineoplastic properties. The single cell gel electrophoresis (Comet assay) is a sensitive technique that allows detecting double- and single-strand DNA breaks caused by a broad spectrum of mutagens. In the present work the ability of curcumin to reduce DNA damage induced by chromium in human lymphocytes and gastric mucosa (GM) cells was investigated by using the comet assay. Chromium at 500 microM evoked DNA damage measured as significant (P < 0.001), about a two-fold increase in comet tail moment of both lymphocytes and GM cells. Curcumin at 10, 25, and 50 microM also damaged DNA of both types of cells in a dose-dependent manner: the increase in the tail moment reached about twenty times of the control value (P < 0.001). The combined action of chromium at 500 microM and curcumin at 50 microM resulted in the significant (P < 0.001) increase in the comet tail moment of both types of cells. In each case, treated cells were able to recover within 60 min. Our study clearly demonstrates that curcumin does not inhibit DNA damaging action of hexavalent chromium in human lymphocytes and GM cells. Moreover, curcumin itself can damage DNA of these cells and the total effect of chromium and curcumin is additive. Further studies are needed to establish the role of interaction of curcumin with DNA in carcinogenesis.","DNA damage and repair in human lymphocytes and gastric mucosa cells exposed to chromium and curcumin Abs: Human population can be considered as a subject of combined exposure to chemicals. Hexavalent chromium is a well-known mutagen and carcinogen. Curcumin, a popular spice and pigment, is reported to have antineoplastic properties. The single cell gel electrophoresis (Comet assay) is a sensitive technique that allows detecting double- and single-strand DNA breaks caused by a broad spectrum of mutagens. In the present work the ability of curcumin to reduce DNA damage induced by chromium in human lymphocytes and gastric mucosa (GM) cells was investigated by using the comet assay. Chromium at 500 microM evoked DNA damage measured as significant (P < 0.001), about a two-fold increase in comet tail moment of both lymphocytes and GM cells. Curcumin at 10, 25, and 50 microM also damaged DNA of both types of cells in a dose-dependent manner: the increase in the tail moment reached about twenty times of the control value (P < 0.001). The combined action of chromium at 500 microM and curcumin at 50 microM resulted in the significant (P < 0.001) increase in the comet tail moment of both types of cells. In each case, treated cells were able to recover within 60 min. Our study clearly demonstrates that curcumin does not inhibit DNA damaging action of hexavalent chromium in human lymphocytes and GM cells. Moreover, curcumin itself can damage DNA of these cells and the total effect of chromium and curcumin is additive. Further studies are needed to establish the role of interaction of curcumin with DNA in carcinogenesis."
1233805,Bradberry and  Vale 1999,Therapeutic review: is ascorbic acid of value in chromium poisoning and chromium dermatitis?,"<strong>INTRODUCTION: </strong>Repeated topical exposure to chromium(VI) may cause an allergic contact dermatitis or the formation of chrome ulcers. Systemic toxicity may occur following the ingestion of a chromium(VI) salt, from chromium(VI)-induced skin burns, or from inhalation of chromium(VI) occurring occupationally. Soluble chromium(VI) salts are usually absorbed more easily and cross cell membranes more readily than trivalent chromium salts, and, therefore chromium(VI) is more toxic than chromium(III). In experimental studies, endogenous ascorbic acid in rat lung, liver, and kidney and human plasma, effectively reduces chromium(VI) to chromium(III). The administration of exogenous ascorbic acid has been advocated therefore in the treatment of systemic chromium poisoning and chromium dermatitis to enhance the extracellular reduction of chromium(VI) to the less bioavailable chromium(III).<br /><br /><strong>REVIEW: </strong>In vitro experiments confirm that the addition of ascorbic acid to plasma containing chromium(VI) leads to a dose-dependent reduction of chromium(VI) to chromium(III). In animal studies, parenteral ascorbic acid 0.5-5 g/kg significantly reduced chromium-induced nephrotoxicity when administered 30 minutes before parenteral sodium dichromate and up to 1 hour after parenteral sodium chromate dosing. Parenteral ascorbic acid 0.5-5 g/kg also reduced mortality when given orally up to 2 hours after oral potassium dichromate dosing. However, the administration of parenteral ascorbic acid more than 2 hours after parenteral chromate in these experimental studies did not protect against renal damage, and parenteral ascorbic acid given 3 hours postparenteral chromate increased toxicity. In addition, there is no confirmed clinical evidence that the administration of ascorbic acid lessens morbidity or mortality in systemic chromium poisoning. A possible reason for the lack of benefit of ascorbic acid when administration is delayed, is that chromium(VI) cellular uptake has occurred prior to ascorbic acid administration. Topical 10% ascorbic acid has been claimed to reduce significantly the healing time of experimentally induced chrome ulcers in guinea pigs. The proposed mechanism is reduction on the skin surface of chromium(VI) to chromium(III). Several case reports suggest that topical ascorbic acid is effective in the management of chromium dermatitis but this has not been confirmed in controlled clinical trials and, moreover, the practical difficulties of frequent application are likely to limit its usefulness.<br /><br /><strong>DISCUSSION: </strong>Based on experimental studies, substantial amounts of ascorbic acid would need to be administered, preferably parenterally, soon after exposure to prevent systemic toxicity from chromium(VI) in humans. However, as ascorbic acid is a metabolic precursor of oxalate, the administration of ascorbic acid in high dose could lead to acute oxalate nephropathy, particularly in the presence of renal failure. While smaller doses of ascorbic acid (e.g., 10 g intravenously) are not toxic, such doses probably will not reduce the mortality from systemic chromium poisoning.<br /><br /><strong>CONCLUSION: </strong>There is currently insufficient evidence to advocate the use of ascorbic acid in the management of systemic chromium toxicity. Topical ascorbic acid may reduce dermal hexavalent chromium exposure, but this observation must be confirmed in controlled studies.","Therapeutic review: is ascorbic acid of value in chromium poisoning and chromium dermatitis? Abs: <strong>INTRODUCTION: </strong>Repeated topical exposure to chromium(VI) may cause an allergic contact dermatitis or the formation of chrome ulcers. Systemic toxicity may occur following the ingestion of a chromium(VI) salt, from chromium(VI)-induced skin burns, or from inhalation of chromium(VI) occurring occupationally. Soluble chromium(VI) salts are usually absorbed more easily and cross cell membranes more readily than trivalent chromium salts, and, therefore chromium(VI) is more toxic than chromium(III). In experimental studies, endogenous ascorbic acid in rat lung, liver, and kidney and human plasma, effectively reduces chromium(VI) to chromium(III). The administration of exogenous ascorbic acid has been advocated therefore in the treatment of systemic chromium poisoning and chromium dermatitis to enhance the extracellular reduction of chromium(VI) to the less bioavailable chromium(III).<br /><br /><strong>REVIEW: </strong>In vitro experiments confirm that the addition of ascorbic acid to plasma containing chromium(VI) leads to a dose-dependent reduction of chromium(VI) to chromium(III). In animal studies, parenteral ascorbic acid 0.5-5 g/kg significantly reduced chromium-induced nephrotoxicity when administered 30 minutes before parenteral sodium dichromate and up to 1 hour after parenteral sodium chromate dosing. Parenteral ascorbic acid 0.5-5 g/kg also reduced mortality when given orally up to 2 hours after oral potassium dichromate dosing. However, the administration of parenteral ascorbic acid more than 2 hours after parenteral chromate in these experimental studies did not protect against renal damage, and parenteral ascorbic acid given 3 hours postparenteral chromate increased toxicity. In addition, there is no confirmed clinical evidence that the administration of ascorbic acid lessens morbidity or mortality in systemic chromium poisoning. A possible reason for the lack of benefit of ascorbic acid when administration is delayed, is that chromium(VI) cellular uptake has occurred prior to ascorbic acid administration. Topical 10% ascorbic acid has been claimed to reduce significantly the healing time of experimentally induced chrome ulcers in guinea pigs. The proposed mechanism is reduction on the skin surface of chromium(VI) to chromium(III). Several case reports suggest that topical ascorbic acid is effective in the management of chromium dermatitis but this has not been confirmed in controlled clinical trials and, moreover, the practical difficulties of frequent application are likely to limit its usefulness.<br /><br /><strong>DISCUSSION: </strong>Based on experimental studies, substantial amounts of ascorbic acid would need to be administered, preferably parenterally, soon after exposure to prevent systemic toxicity from chromium(VI) in humans. However, as ascorbic acid is a metabolic precursor of oxalate, the administration of ascorbic acid in high dose could lead to acute oxalate nephropathy, particularly in the presence of renal failure. While smaller doses of ascorbic acid (e.g., 10 g intravenously) are not toxic, such doses probably will not reduce the mortality from systemic chromium poisoning.<br /><br /><strong>CONCLUSION: </strong>There is currently insufficient evidence to advocate the use of ascorbic acid in the management of systemic chromium toxicity. Topical ascorbic acid may reduce dermal hexavalent chromium exposure, but this observation must be confirmed in controlled studies."
1233803,Messer et al. 1999,Effects of metallic ion toxicity on human gingival fibroblasts morphology,"Alloys used as implant materials release metal ions to surrounding tissues. Cytotoxic substances attack at the molecular level, and these effects are reflected in the structure of the cells and organelles. The objective of this study was to evaluate the cellular morphology and ultrastructural changes of cultured human gingival fibroblasts to salt solutions of ions (beryllium (Be+2), chromium (Cr+6 and Cr+3), nickel (Ni+2), molybdenum (Mo+6)) which may be released from nickel-chromium dental alloys. The concentrations chosen were based on previously conducted cell culture studies. Fibroblasts were exposed to the different ion concentrations for 24 or 72 h. Cellular morphology and ultrastructural features were examined using scanning electron microscopy and transmission electron microscopy. Ultrastructural alterations observed included irregular shaped nuclei for cells exposed to hexavalent chromium and nickel, pseudopodia for cells exposed to beryllium and molybdenum, and lipid droplet formation in cells exposed to nickel.","Effects of metallic ion toxicity on human gingival fibroblasts morphology Abs: Alloys used as implant materials release metal ions to surrounding tissues. Cytotoxic substances attack at the molecular level, and these effects are reflected in the structure of the cells and organelles. The objective of this study was to evaluate the cellular morphology and ultrastructural changes of cultured human gingival fibroblasts to salt solutions of ions (beryllium (Be+2), chromium (Cr+6 and Cr+3), nickel (Ni+2), molybdenum (Mo+6)) which may be released from nickel-chromium dental alloys. The concentrations chosen were based on previously conducted cell culture studies. Fibroblasts were exposed to the different ion concentrations for 24 or 72 h. Cellular morphology and ultrastructural features were examined using scanning electron microscopy and transmission electron microscopy. Ultrastructural alterations observed included irregular shaped nuclei for cells exposed to hexavalent chromium and nickel, pseudopodia for cells exposed to beryllium and molybdenum, and lipid droplet formation in cells exposed to nickel."
1233802,Shakoori et al. 1999,Chromium-tolerant bacteria isolated from industrial effluents and their use in detoxication of hexavalent chromium,"Three bacterial strains were isolated from effluents of leather (CMBL Cr13, CMBL Cr14) and steel (CMBL Cr15) industries for their possible use in chromium(VI) detoxication of industrial waste. CMBL Cr13 was found to tolerate chromium(VI) up to a concentration of 45 g/L in the medium, while CMBL Cr14 and CMBL Cr15 could tolerate up to 40 g/L. These bacteria were also checked for resistance to other metals. They resisted a lead concentration of 1 g/L and cadmium concentration of 550 mg/L in the medium. They showed optimum growth at pH 7.3-7.5 at a temperature of 35-37 degrees C. CrVI-reducing ability of the three strains ranged from 70 to 80% after 3 d of incubation. The possible use of these bacteria in environmental cleanup is discussed.","Chromium-tolerant bacteria isolated from industrial effluents and their use in detoxication of hexavalent chromium Abs: Three bacterial strains were isolated from effluents of leather (CMBL Cr13, CMBL Cr14) and steel (CMBL Cr15) industries for their possible use in chromium(VI) detoxication of industrial waste. CMBL Cr13 was found to tolerate chromium(VI) up to a concentration of 45 g/L in the medium, while CMBL Cr14 and CMBL Cr15 could tolerate up to 40 g/L. These bacteria were also checked for resistance to other metals. They resisted a lead concentration of 1 g/L and cadmium concentration of 550 mg/L in the medium. They showed optimum growth at pH 7.3-7.5 at a temperature of 35-37 degrees C. CrVI-reducing ability of the three strains ranged from 70 to 80% after 3 d of incubation. The possible use of these bacteria in environmental cleanup is discussed."
1233801,Sakurai et al. 1999,ESR characterization and metallokinetic analysis of Cr(V) in the blood of rats given carcinogen chromate(VI) compounds,"It has been shown that bio-trace metal elements are related to many diseases and the aging process. For many years, carcinogen hexavalent chromium (VI) has been known to be toxic to animals, but its dynamic toxicological mechanism is not sufficiently elucidated. Bioinorganic chemistry in terms of metallokinetic analysis of beneficial or toxic metal ions and their complexes is an important investigation for understanding their biochemical and physiological roles. We have tried to examine the real-time behavior of paramagnetic metal ions and complexes in animals, in which electron spin resonance (ESR) was capable of measuring paramagnetic species in chemical and biological systems. On the basis of our previous results on stable nitroxide spin probes, we have developed the in vivo blood circulation monitoring-electron spin resonance (BCM-ESR) method to analyze time-dependent ESR signal changes due to paramagnetic metal ions and their complexes in real time. When K2Cr2O7 or Na2Cr2O7 in saline was intravenously administered to rats, two ESR signals due to pentavalent chromium(V) were detectable in the circulating blood of rats. Cr(V) detected in the blood was indicated to be in the CrO(O4) and CrO(S2O2) coordination modes after the study on model complexes. From the changes of ESR signal intensities due to Cr(V) in the blood, the metallokinetic parameters were obtained using the pharmacokinetic analysis and the curve-fitting methods. The obtained results are important for understanding carcinogen chromate in terms of the formation of Cr(V) in animals. In addition, we propose the BCM-ESR method, which is useful to analyze the disposition of paramagnetic metal species in the blood of living animals.","ESR characterization and metallokinetic analysis of Cr(V) in the blood of rats given carcinogen chromate(VI) compounds Abs: It has been shown that bio-trace metal elements are related to many diseases and the aging process. For many years, carcinogen hexavalent chromium (VI) has been known to be toxic to animals, but its dynamic toxicological mechanism is not sufficiently elucidated. Bioinorganic chemistry in terms of metallokinetic analysis of beneficial or toxic metal ions and their complexes is an important investigation for understanding their biochemical and physiological roles. We have tried to examine the real-time behavior of paramagnetic metal ions and complexes in animals, in which electron spin resonance (ESR) was capable of measuring paramagnetic species in chemical and biological systems. On the basis of our previous results on stable nitroxide spin probes, we have developed the in vivo blood circulation monitoring-electron spin resonance (BCM-ESR) method to analyze time-dependent ESR signal changes due to paramagnetic metal ions and their complexes in real time. When K2Cr2O7 or Na2Cr2O7 in saline was intravenously administered to rats, two ESR signals due to pentavalent chromium(V) were detectable in the circulating blood of rats. Cr(V) detected in the blood was indicated to be in the CrO(O4) and CrO(S2O2) coordination modes after the study on model complexes. From the changes of ESR signal intensities due to Cr(V) in the blood, the metallokinetic parameters were obtained using the pharmacokinetic analysis and the curve-fitting methods. The obtained results are important for understanding carcinogen chromate in terms of the formation of Cr(V) in animals. In addition, we propose the BCM-ESR method, which is useful to analyze the disposition of paramagnetic metal species in the blood of living animals."
1233800,Blot et al. 2000,A cohort mortality study among gas generator utility workers,"An earlier cohort study tracked the mortality experience through 1988 of male employees at five utility companies in the United States. Workers employed by the Pacific Gas and Electric Company (PG&amp;E) were part of that study, but results for PG&amp;E employees overall or for those involved in gas generator plant operations where hexavalent chromium compounds were used in open and closed systems from the 1950s to early 1980s were not reported. To evaluate risk of lung cancer and other diseases, a cohort of 51,899 PG&amp;E male workers was followed for mortality from 1971 through 1997. Observed numbers of deaths were compared with those expected based on rates in the general California population, with standardized mortality ratios (SMR) and corresponding 95% confidence intervals (CI) calculated for the total cohort and for subsets defined by potential for gas generator plant exposure. A total of 10,591 deaths were observed, a number significantly less than expected (SMR, 0.89; 95% CI, 0.87 to 0.91). No significant excesses of total or specific cancers were observed, with SMR typically near or below 1.0. Lung cancer mortality in the entire cohort was close to expected (SMR, 0.98; 95% CI, 0.92 to 1.05), with no excess detected among persons who worked (SMR, 0.81; 95% CI, 0.35 to 1.60) or trained (SMR, 0.57; 95% CI, 0.12 to 1.67) at gas generator facilities. Furthermore, risk of lung cancer did not increase with increasing duration of employment or time since hire. The study thus provides no evidence that occupational exposures at PG&amp;E facilities resulted in increased risk of lung cancer or any other cause of death. The results indicate that any chromium exposures were of insufficient magnitude to result in increased risk of lung cancer.","A cohort mortality study among gas generator utility workers Abs: An earlier cohort study tracked the mortality experience through 1988 of male employees at five utility companies in the United States. Workers employed by the Pacific Gas and Electric Company (PG&amp;E) were part of that study, but results for PG&amp;E employees overall or for those involved in gas generator plant operations where hexavalent chromium compounds were used in open and closed systems from the 1950s to early 1980s were not reported. To evaluate risk of lung cancer and other diseases, a cohort of 51,899 PG&amp;E male workers was followed for mortality from 1971 through 1997. Observed numbers of deaths were compared with those expected based on rates in the general California population, with standardized mortality ratios (SMR) and corresponding 95% confidence intervals (CI) calculated for the total cohort and for subsets defined by potential for gas generator plant exposure. A total of 10,591 deaths were observed, a number significantly less than expected (SMR, 0.89; 95% CI, 0.87 to 0.91). No significant excesses of total or specific cancers were observed, with SMR typically near or below 1.0. Lung cancer mortality in the entire cohort was close to expected (SMR, 0.98; 95% CI, 0.92 to 1.05), with no excess detected among persons who worked (SMR, 0.81; 95% CI, 0.35 to 1.60) or trained (SMR, 0.57; 95% CI, 0.12 to 1.67) at gas generator facilities. Furthermore, risk of lung cancer did not increase with increasing duration of employment or time since hire. The study thus provides no evidence that occupational exposures at PG&amp;E facilities resulted in increased risk of lung cancer or any other cause of death. The results indicate that any chromium exposures were of insufficient magnitude to result in increased risk of lung cancer."
1233799,Saito et al. 2000,Laboratory measurement of hazardous fumes and gases at a point corresponding to breathing zone of welder during a CO2 arc welding,"Concentrations of fumes, ozone (O3), carbon monoxide (CO), nitric oxide (NO), manganese (Mn) and total and hexavalent chromium (Cr) as well as size distribution of fumes were measured at a point corresponding to the welder's breathing zone during CO2-arc welding, using a welding robot and three kinds of wires. Concentrations of fumes, O3, CO, Mn and total-Cr were found to exceed their corresponding occupational exposure limit (OEL) values, while the concentrations of NO and Cr(VI) were below those OEL levels. Airborne concentration of Mn exceeded its OEL value, and the Mn content was 8 times higher in welding fumes than in the wire. Using an additive equation of OEL and exposure concentration of each hazardous component, health risk in welders with combined exposure to welding fumes and gases was assessed as 18.6 to 46.0 times of OEL, which exceeded the unity. This finding suggests that effective protection of welders from the exposure can be attained by use of the supplied-air respirator or combined use of a dust respirator and a local exhaust system.","Laboratory measurement of hazardous fumes and gases at a point corresponding to breathing zone of welder during a CO2 arc welding Abs: Concentrations of fumes, ozone (O3), carbon monoxide (CO), nitric oxide (NO), manganese (Mn) and total and hexavalent chromium (Cr) as well as size distribution of fumes were measured at a point corresponding to the welder's breathing zone during CO2-arc welding, using a welding robot and three kinds of wires. Concentrations of fumes, O3, CO, Mn and total-Cr were found to exceed their corresponding occupational exposure limit (OEL) values, while the concentrations of NO and Cr(VI) were below those OEL levels. Airborne concentration of Mn exceeded its OEL value, and the Mn content was 8 times higher in welding fumes than in the wire. Using an additive equation of OEL and exposure concentration of each hazardous component, health risk in welders with combined exposure to welding fumes and gases was assessed as 18.6 to 46.0 times of OEL, which exceeded the unity. This finding suggests that effective protection of welders from the exposure can be attained by use of the supplied-air respirator or combined use of a dust respirator and a local exhaust system."
1233798,Carlisle et al. 2000,Apoptosis and P53 induction in human lung fibroblasts exposed to chromium (VI): Effect of ascorbate and tocopherol,"Some forms of hexavalent chromium [Cr(VI)] are known to cause damage to respiratory tract tissue, and are thought to be human lung carcinogens. Because Cr(VI) is mutagenic and carcinogenic at doses that evoke cell toxicity, the objective of these experiments was to examine the effect of Cr(VI) on the growth, survival, and mode of cell death in normal human lung fibroblasts (HLF cells). DNA adduct formation was monitored as a marker for bioavailability of genotoxic chromium. We also examined the modulation of these endpoints by vitamins C and E. Long-term Cr(VI) exposures were employed, which decreased clonogenic cell survival by 25% to 95% in a dose-dependent manner. The predominant cellular response to Cr(VI) was growth arrest. We found that Cr(VI) caused up to 20% of HLF cells to undergo apoptosis, and documented apoptotic morphology and the phagocytosis of apoptotic bodies by neighboring cells. P53 levels increased 4- to 6-fold in chromium-treated cells. In contrast with previous studies using CHO cells, the present study using HLFs found that pretreatment with either vitamin C or E did not exhibit a significant effect on Cr-induced apoptosis or clonogenic survival. In addition, pretreatment with vitamin C did not affect the p53 induction observed after chromium treatment. Neither vitamin had any effect on Cr-DNA adduct formation. These data indicate that although pretreatment with vitamin C or E alters the spectrum of cellular and/or genetic lesions induced by chromium(VI), neither vitamin altered the initiation or progression of apoptosis in diploid human lung cells.","Apoptosis and P53 induction in human lung fibroblasts exposed to chromium (VI): Effect of ascorbate and tocopherol Abs: Some forms of hexavalent chromium [Cr(VI)] are known to cause damage to respiratory tract tissue, and are thought to be human lung carcinogens. Because Cr(VI) is mutagenic and carcinogenic at doses that evoke cell toxicity, the objective of these experiments was to examine the effect of Cr(VI) on the growth, survival, and mode of cell death in normal human lung fibroblasts (HLF cells). DNA adduct formation was monitored as a marker for bioavailability of genotoxic chromium. We also examined the modulation of these endpoints by vitamins C and E. Long-term Cr(VI) exposures were employed, which decreased clonogenic cell survival by 25% to 95% in a dose-dependent manner. The predominant cellular response to Cr(VI) was growth arrest. We found that Cr(VI) caused up to 20% of HLF cells to undergo apoptosis, and documented apoptotic morphology and the phagocytosis of apoptotic bodies by neighboring cells. P53 levels increased 4- to 6-fold in chromium-treated cells. In contrast with previous studies using CHO cells, the present study using HLFs found that pretreatment with either vitamin C or E did not exhibit a significant effect on Cr-induced apoptosis or clonogenic survival. In addition, pretreatment with vitamin C did not affect the p53 induction observed after chromium treatment. Neither vitamin had any effect on Cr-DNA adduct formation. These data indicate that although pretreatment with vitamin C or E alters the spectrum of cellular and/or genetic lesions induced by chromium(VI), neither vitamin altered the initiation or progression of apoptosis in diploid human lung cells."
1233796,Shakoori et al. 2000,Hexavalent chromium reduction by a dichromate-resistant gram-positive bacterium isolated from effluents of tanneries,"A gram-positive, chromium (Cr)-resistant bacterial strain (ATCC 700729) was isolated from effluent of tanneries. It was grown in media containing potassium dichromate concentration up to 80 mg ml(-1) of the medium. The dichromate reducing capability of the bacterium was checked by estimating the amount of Cr VI in the medium before and after introduction of bacterial culture. The influence of factors like pH of the medium, concentration of Cr, and the amount of the inoculum was studied to determine the ability of the bacterium to reduce Cr VI in the medium under various conditions. In a medium containing dichromate 20 mg ml(-1) more than 87% reduction of dichromate ions was achieved within 72 h. The feasibility of the use of this bacterial strain for detoxification of dichromate in the industrial wastewater has been assessed. The isolated strain can be exploited for specific environmental clean-up operations.","Hexavalent chromium reduction by a dichromate-resistant gram-positive bacterium isolated from effluents of tanneries Abs: A gram-positive, chromium (Cr)-resistant bacterial strain (ATCC 700729) was isolated from effluent of tanneries. It was grown in media containing potassium dichromate concentration up to 80 mg ml(-1) of the medium. The dichromate reducing capability of the bacterium was checked by estimating the amount of Cr VI in the medium before and after introduction of bacterial culture. The influence of factors like pH of the medium, concentration of Cr, and the amount of the inoculum was studied to determine the ability of the bacterium to reduce Cr VI in the medium under various conditions. In a medium containing dichromate 20 mg ml(-1) more than 87% reduction of dichromate ions was achieved within 72 h. The feasibility of the use of this bacterial strain for detoxification of dichromate in the industrial wastewater has been assessed. The isolated strain can be exploited for specific environmental clean-up operations."
1233795,Smith and  Gadd 2000,Reduction and precipitation of chromate by mixed culture sulphate-reducing bacterial biofilms,"The ability of sulphate-reducing bacterial biofilms to reduce hexavalent chromium (Cr(VI)) to insoluble Cr(III), a process of environmental and biotechnological significance, was investigated. The reduction of chromate to insoluble form has been quantified and the effects of chromate on the carbon source utilization and sulphate-reducing activity of the bacterial biofilms evaluated. Using lactate as the carbon/energy source and in the presence of sulphate, reduction of 500 micromol l-1 Cr(VI) was monitored over a 48-h period where 88% of the total chromium was removed from solution. Mass balance calculations showed that ca 80% of the total chromium was precipitated out of solution with the bacterial biofilm retaining less than 10% of the chromium. Only ca 12% of the chromate added was not reduced to insoluble form. Although Cr(VI) did not have a significant effect on C source utilization, sulphate reduction was severely inhibited by 500 micromol-1 Cr(VI) and only ca 10% of the sulphate reducing activity detected in control biofilms occurred in the presence of Cr(VI). Low levels of sulphide were also produced in the presence of chromate, with control biofilms producing over 10-times more sulphide than Cr(VI)-exposed biofilms. Sulphide- or other chemically-mediated Cr(VI) reduction was not detected. The biological mechanism of Cr(VI) reduction is likely to be similar to that found in other sulphate-reducing bacteria.","Reduction and precipitation of chromate by mixed culture sulphate-reducing bacterial biofilms Abs: The ability of sulphate-reducing bacterial biofilms to reduce hexavalent chromium (Cr(VI)) to insoluble Cr(III), a process of environmental and biotechnological significance, was investigated. The reduction of chromate to insoluble form has been quantified and the effects of chromate on the carbon source utilization and sulphate-reducing activity of the bacterial biofilms evaluated. Using lactate as the carbon/energy source and in the presence of sulphate, reduction of 500 micromol l-1 Cr(VI) was monitored over a 48-h period where 88% of the total chromium was removed from solution. Mass balance calculations showed that ca 80% of the total chromium was precipitated out of solution with the bacterial biofilm retaining less than 10% of the chromium. Only ca 12% of the chromate added was not reduced to insoluble form. Although Cr(VI) did not have a significant effect on C source utilization, sulphate reduction was severely inhibited by 500 micromol-1 Cr(VI) and only ca 10% of the sulphate reducing activity detected in control biofilms occurred in the presence of Cr(VI). Low levels of sulphide were also produced in the presence of chromate, with control biofilms producing over 10-times more sulphide than Cr(VI)-exposed biofilms. Sulphide- or other chemically-mediated Cr(VI) reduction was not detected. The biological mechanism of Cr(VI) reduction is likely to be similar to that found in other sulphate-reducing bacteria."
1233794,Carlisle et al. 2000,Chromium(VI) induces p53-dependent apoptosis in diploid human lung and mouse dermal fibroblasts,"Some forms of hexavalent chromium [Cr(VI)] are known to cause damage to respiratory-tract tissue and DNA and are thought to be human lung carcinogens. In general, Cr(VI) is mutagenic and carcinogenic at doses that also evoke some cell death, and we previously showed that the predominant mode of death is apoptosis. Because p53 has been shown to initiate apoptosis after genotoxic insults, the objective of these experiments was to determine whether p53 is activated in and necessary for apoptosis of normal diploid human lung fibroblasts (HLF cells) after chromium exposure. By using annexin(V) staining and fluorescent microscopy, we found that Cr(VI) caused up to 14% of HLF cells to undergo apoptosis within 24 h after exposure. In addition, by using western blotting, we found that p53 protein levels increased fourfold to sixfold after exposure to sodium chromate. Because the major function of p53 is as a transcription factor, it must be translocated from the cytoplasm to the nucleus after chromate exposure to be active. Immunofluorescence studies using an antibody against p53 showed that, after chromate exposure, p53 was located in the nucleus of the treated HLF cells. The necessity of p53 for chromium-induced apoptosis was examined in two ways. One approach used dermal fibroblasts from p53 wild-type, heterozygous, and null mice, and the other approach used HLF cells that were transiently transfected with the human papilloma virus E6 gene, which targets p53 for degradation and creates a functional p53-null cell. These studies showed that chromium-induced apoptosis was p53 dependent. Mol. Carcinog. 28:111-118, 2000.","Chromium(VI) induces p53-dependent apoptosis in diploid human lung and mouse dermal fibroblasts Abs: Some forms of hexavalent chromium [Cr(VI)] are known to cause damage to respiratory-tract tissue and DNA and are thought to be human lung carcinogens. In general, Cr(VI) is mutagenic and carcinogenic at doses that also evoke some cell death, and we previously showed that the predominant mode of death is apoptosis. Because p53 has been shown to initiate apoptosis after genotoxic insults, the objective of these experiments was to determine whether p53 is activated in and necessary for apoptosis of normal diploid human lung fibroblasts (HLF cells) after chromium exposure. By using annexin(V) staining and fluorescent microscopy, we found that Cr(VI) caused up to 14% of HLF cells to undergo apoptosis within 24 h after exposure. In addition, by using western blotting, we found that p53 protein levels increased fourfold to sixfold after exposure to sodium chromate. Because the major function of p53 is as a transcription factor, it must be translocated from the cytoplasm to the nucleus after chromate exposure to be active. Immunofluorescence studies using an antibody against p53 showed that, after chromate exposure, p53 was located in the nucleus of the treated HLF cells. The necessity of p53 for chromium-induced apoptosis was examined in two ways. One approach used dermal fibroblasts from p53 wild-type, heterozygous, and null mice, and the other approach used HLF cells that were transiently transfected with the human papilloma virus E6 gene, which targets p53 for degradation and creates a functional p53-null cell. These studies showed that chromium-induced apoptosis was p53 dependent. Mol. Carcinog. 28:111-118, 2000."
1233793,Aizenberg et al. 2000,Metal exposure among abrasive blasting workers at four U.S. Air Force facilities,"Button Aerosol Samplers were used to monitor the personal exposure of workers performing abrasive blasting operations at four U.S. Air Force facilities. Inhalable aerosols containing 25 metals, including cadmium, lead, and chromium, were investigated. The Button Aerosol Sampler was chosen because of its ability to successfully withstand mechanical stress, prevent very large particles from collection, and protect the filter from overloading and shredding by rebound particles. In addition, previous studies have shown that the sampling efficiency of this personal Aerosol Sampler exhibits low sensitivity to the ambient air conditions and that it adequately follows the inhalability convention. Inductively coupled plasma (ICP) was used to analyze the collected samples for all 25 metals. In addition, visual absorption spectrophotometry (VAS) was used to analyze for hexavalent chromium because of the presence of strontium chromate. The collected samples yielded 8-hr time-weighted average (TWA) concentrations that were up to 250, 6, and 5 times higher than the permissible exposure limits (PELs) for cadmium, lead, and hexavalent chromium, respectively. Also, the chromium levels measured by the ICP and VAS exceeded the strontium chromate threshold limit value (TLV) by up to 640 and 950 times, respectively. No correlation was found between the ICP and VAS hexavalent chromium concentrations. The likely reasons of this were the presence of Cr (II) and (III) that cannot be detected by the VAS, and the chemical interference from iron and some other metals in the samples. The Button Aerosol Sampler was shown to be useful for the monitoring of workers' exposure to heavy metals during abrasive blasting operations.","Metal exposure among abrasive blasting workers at four U.S. Air Force facilities Abs: Button Aerosol Samplers were used to monitor the personal exposure of workers performing abrasive blasting operations at four U.S. Air Force facilities. Inhalable aerosols containing 25 metals, including cadmium, lead, and chromium, were investigated. The Button Aerosol Sampler was chosen because of its ability to successfully withstand mechanical stress, prevent very large particles from collection, and protect the filter from overloading and shredding by rebound particles. In addition, previous studies have shown that the sampling efficiency of this personal Aerosol Sampler exhibits low sensitivity to the ambient air conditions and that it adequately follows the inhalability convention. Inductively coupled plasma (ICP) was used to analyze the collected samples for all 25 metals. In addition, visual absorption spectrophotometry (VAS) was used to analyze for hexavalent chromium because of the presence of strontium chromate. The collected samples yielded 8-hr time-weighted average (TWA) concentrations that were up to 250, 6, and 5 times higher than the permissible exposure limits (PELs) for cadmium, lead, and hexavalent chromium, respectively. Also, the chromium levels measured by the ICP and VAS exceeded the strontium chromate threshold limit value (TLV) by up to 640 and 950 times, respectively. No correlation was found between the ICP and VAS hexavalent chromium concentrations. The likely reasons of this were the presence of Cr (II) and (III) that cannot be detected by the VAS, and the chemical interference from iron and some other metals in the samples. The Button Aerosol Sampler was shown to be useful for the monitoring of workers' exposure to heavy metals during abrasive blasting operations."
1233792,Pritchard et al. 2000,Cyclosporin A inhibits chromium(VI)-induced apoptosis and mitochondrial cytochrome c release and restores clonogenic survival in CHO cells,"A variety of key events in the molecular apoptotic pathway involve the mitochondria. Cyclosporin A (csA) affects the mitochondria by inhibiting the mitochondrial permeability transition (MPT), thereby preventing disruption of the transmembrane potential. The role of the MPT in apoptosis is not fully understood, but inhibition of the MPT may prevent the release of mitochondrial caspase activators, such as cytochrome c (cyt c), into the cytosol. Certain hexavalent chromium [Cr(VI)] compounds are known occupational respiratory tract toxins and carcinogens. We have previously shown that these compounds induce apoptosis as a predominant mode of cell death and that this effect can be observed in cell culture using soluble Cr(VI). We show here that Cr(VI)-induced apoptosis in Chinese hamster ovary (CHO) cells involves disruption of mitochondrial stability. Using a cyt c-specific monoclonal antibody, we observed a dose-dependent release of mitochondrial cyt c in cytosolic extracts of CHO cells exposed to apoptogenic doses of sodium chromate. Co-treatment of these cells with csA inhibited the release of cyt c and abrogated Cr(VI)-induced apoptosis as determined by a reduction in internucleosomal DNA fragmentation. Co-treatment with csA also markedly increased clonogenic survival of Cr(VI)-treated CHO cells. In contrast, the general caspase inhibitor Z-VAD-FMK markedly inhibited most of the morphological and biochemical parameters of apoptosis but did not prevent cyt c release and did not increase clonogenic survival. These results suggest that the MPT plays an important role in the regulation of mitochondrial cyt c release and that this may be a critical point in the apoptotic pathway in which cells are irreversibly committed to death.","Cyclosporin A inhibits chromium(VI)-induced apoptosis and mitochondrial cytochrome c release and restores clonogenic survival in CHO cells Abs: A variety of key events in the molecular apoptotic pathway involve the mitochondria. Cyclosporin A (csA) affects the mitochondria by inhibiting the mitochondrial permeability transition (MPT), thereby preventing disruption of the transmembrane potential. The role of the MPT in apoptosis is not fully understood, but inhibition of the MPT may prevent the release of mitochondrial caspase activators, such as cytochrome c (cyt c), into the cytosol. Certain hexavalent chromium [Cr(VI)] compounds are known occupational respiratory tract toxins and carcinogens. We have previously shown that these compounds induce apoptosis as a predominant mode of cell death and that this effect can be observed in cell culture using soluble Cr(VI). We show here that Cr(VI)-induced apoptosis in Chinese hamster ovary (CHO) cells involves disruption of mitochondrial stability. Using a cyt c-specific monoclonal antibody, we observed a dose-dependent release of mitochondrial cyt c in cytosolic extracts of CHO cells exposed to apoptogenic doses of sodium chromate. Co-treatment of these cells with csA inhibited the release of cyt c and abrogated Cr(VI)-induced apoptosis as determined by a reduction in internucleosomal DNA fragmentation. Co-treatment with csA also markedly increased clonogenic survival of Cr(VI)-treated CHO cells. In contrast, the general caspase inhibitor Z-VAD-FMK markedly inhibited most of the morphological and biochemical parameters of apoptosis but did not prevent cyt c release and did not increase clonogenic survival. These results suggest that the MPT plays an important role in the regulation of mitochondrial cyt c release and that this may be a critical point in the apoptotic pathway in which cells are irreversibly committed to death."
1233790,Arunkumar et al. 2000,Differential effect of chromium compounds on the immune response of the African mouth breeder Oreochromis mossambicus (Peters),"The objective of this study was to investigate the effect of trivalent (chromic chloride) and hexavalent (potassium dichromate) forms of chromium in the African mouth breeder Oreochromis mossambicus (Peters), with reference to the humoral immune response and lymphoid cells/organs. The 96 h LD50 for hexavalent and trivalent chromium was found to be 75 and 1,000microg fish(-1), respectively. Groups of fishes were injected intraperitoneally with 10, 1, 0.1 and 0.01% LD50 hexavalent and trivalent forms of chromium and subsequently immunised with bovine serum albumin (5 mg in 0.2 ml physiological saline). Both forms of chromium suppressed the antibody response, with hexavalent chromium being more suppressive than trivalent chromium. Reduction in spleen weight, splenocyte number and the percentage of blood lymphocytes was observed following administration of both forms of chromium. The possible immunological mechanisms behind the differential suppression of the antibody response and the reduction in spleen weight, splenocyte and lymphocyte counts are discussed.","Differential effect of chromium compounds on the immune response of the African mouth breeder Oreochromis mossambicus (Peters) Abs: The objective of this study was to investigate the effect of trivalent (chromic chloride) and hexavalent (potassium dichromate) forms of chromium in the African mouth breeder Oreochromis mossambicus (Peters), with reference to the humoral immune response and lymphoid cells/organs. The 96 h LD50 for hexavalent and trivalent chromium was found to be 75 and 1,000microg fish(-1), respectively. Groups of fishes were injected intraperitoneally with 10, 1, 0.1 and 0.01% LD50 hexavalent and trivalent forms of chromium and subsequently immunised with bovine serum albumin (5 mg in 0.2 ml physiological saline). Both forms of chromium suppressed the antibody response, with hexavalent chromium being more suppressive than trivalent chromium. Reduction in spleen weight, splenocyte number and the percentage of blood lymphocytes was observed following administration of both forms of chromium. The possible immunological mechanisms behind the differential suppression of the antibody response and the reduction in spleen weight, splenocyte and lymphocyte counts are discussed."
1233789,Haq et al. 2000,Effect of dichromate on population and growth of various protozoa isolated from industrial effluents,"Three protozoa belonging to genera Euglena, Vorticella and Stylonychia collected from industrial wastes were cultured in a medium containing inorganic salts, basically meant for the growth of algae. Protozoa showed rapid growth in the medium. Hexavalent chromium (K2Cr2O7) at a concentration of 5 micrograms/L in the medium adversely affected the growth of protozoa. At the end of eight days of Cr administration, the population of Euglena, Vorticella and Stylonychia increased 8-, 4.5- and 10-fold, respectively, as against 30-, 6.75- and 50-fold increase in the control cultures. No apparent death phase and no change in activity or morphology of protozoa was observed at this Cr concentration. The protozoa were also exposed to different metal ions, viz. Pb (2.42 mmol/L), Cr (0.48 mmol/L), Cd (0.36 mmol/L), administered in the culture medium for a period of 2 years. The metal tolerance for S. mytilus and V. microstoma was Pb &gt; Cr &gt; Cd. E. proxima could not tolerate any of the long-term metal treatments. Because of the ability of these protozoa to tolerate high concentrations of heavy metals, their potential role in remediation of heavy metals from industrial wastewater is considered.","Effect of dichromate on population and growth of various protozoa isolated from industrial effluents Abs: Three protozoa belonging to genera Euglena, Vorticella and Stylonychia collected from industrial wastes were cultured in a medium containing inorganic salts, basically meant for the growth of algae. Protozoa showed rapid growth in the medium. Hexavalent chromium (K2Cr2O7) at a concentration of 5 micrograms/L in the medium adversely affected the growth of protozoa. At the end of eight days of Cr administration, the population of Euglena, Vorticella and Stylonychia increased 8-, 4.5- and 10-fold, respectively, as against 30-, 6.75- and 50-fold increase in the control cultures. No apparent death phase and no change in activity or morphology of protozoa was observed at this Cr concentration. The protozoa were also exposed to different metal ions, viz. Pb (2.42 mmol/L), Cr (0.48 mmol/L), Cd (0.36 mmol/L), administered in the culture medium for a period of 2 years. The metal tolerance for S. mytilus and V. microstoma was Pb &gt; Cr &gt; Cd. E. proxima could not tolerate any of the long-term metal treatments. Because of the ability of these protozoa to tolerate high concentrations of heavy metals, their potential role in remediation of heavy metals from industrial wastewater is considered."
1233788,Mclean et al. 2000,Isolation and characterization of a chromium-reducing bacterium from a chromated copper arsenate-contaminated site,"A Gram-negative bacterium (CRB5) was isolated from a chromium-contaminated site that was capable of reducing hexavalent chromium to an insoluble precipitate, thereby removing this toxic chromium species from solution. Analysis of the 16S rRNA from the isolate revealed that it was a pseudomonad with high similarity to Pseudomaonas synxantha. CRB5 was tolerant to high concentrations of chromate (500 mg l(-1)) and can reduce Cr(VI) under aerobic and anaerobic conditions. It also exhibited a broad range of reduction efficiencies under minimal nutrient conditions at temperatures between 4 degrees C and 37 degrees C and at pH levels from 4 to 9. As reduction increased, so did total cellular protein, indicating that cell growth was a requirement for reduction. Under low nutrient conditions with CRB5 or when using non-sterile contaminated groundwater from the site, reduction of Cr(VI) was followed by a increase in solution turbidity as a result of the formation of fine-grained Cr(III) precipitates, most probably chromium hydroxide mineral phases such as Cr(OH)3. Chromium adsorption and precipitation, as observed by transmission electron microscopy coupled with energy dispersive X-ray spectroscopy (TEM/EDS), revealed that the surfaces of the cells were uniformly stained with bound Cr(III) and amorphous precipitates (as determined by selected area electron diffraction; SAED). A mass balance of chromium in a batch bioreactor revealed that up to 30% of the total Cr was as settable precipitates or bound to cells.","Isolation and characterization of a chromium-reducing bacterium from a chromated copper arsenate-contaminated site Abs: A Gram-negative bacterium (CRB5) was isolated from a chromium-contaminated site that was capable of reducing hexavalent chromium to an insoluble precipitate, thereby removing this toxic chromium species from solution. Analysis of the 16S rRNA from the isolate revealed that it was a pseudomonad with high similarity to Pseudomaonas synxantha. CRB5 was tolerant to high concentrations of chromate (500 mg l(-1)) and can reduce Cr(VI) under aerobic and anaerobic conditions. It also exhibited a broad range of reduction efficiencies under minimal nutrient conditions at temperatures between 4 degrees C and 37 degrees C and at pH levels from 4 to 9. As reduction increased, so did total cellular protein, indicating that cell growth was a requirement for reduction. Under low nutrient conditions with CRB5 or when using non-sterile contaminated groundwater from the site, reduction of Cr(VI) was followed by a increase in solution turbidity as a result of the formation of fine-grained Cr(III) precipitates, most probably chromium hydroxide mineral phases such as Cr(OH)3. Chromium adsorption and precipitation, as observed by transmission electron microscopy coupled with energy dispersive X-ray spectroscopy (TEM/EDS), revealed that the surfaces of the cells were uniformly stained with bound Cr(III) and amorphous precipitates (as determined by selected area electron diffraction; SAED). A mass balance of chromium in a batch bioreactor revealed that up to 30% of the total Cr was as settable precipitates or bound to cells."
1233787,Trzeciak et al. 2000,Genotoxicity of chromium in human gastric mucosa cells and peripheral blood lymphocytes evaluated by the single cell gel electrophoresis (comet assay),"Hexavalent chromium compounds are well-recognized carcinogens. They easily penetrate the cell membrane and are reduced inside the cell to their trivalent form, which is supposed to react directly with DNA. Chromium is present in some workplaces as well as in water resources and food chain, so it can interact with the mucosa of the gastrointestinal tract. In order to elucidate the genotoxic potency of chromium in human gastric mucosa (GM) cells, the DNA-damaging effect of potassium dichromate (K2Cr2O7) was investigated using alkaline single cell gel electrophoresis (comet assay). Biopsy samples were obtained during gastroscopy from macroscopically healthy tissue of the stomach. Parallel test with human peripheral blood lymphocytes was also performed. Both types of cells were incubated at 37 degrees C with 1.6 mM of K2Cr2O7 for 1 h and after washing, were placed in a chromium-free medium to examine DNA repair. Alkaline single cell gel electrophoresis (comet assay) was used to assess DNA damage and repair. Chromium introduced a damage to DNA both in the GM cells and lymphocytes. The effect induced by K2Cr2O7 in GM cells was comparable with that caused in the lymphocytes. Treated cells were able to recover within a 60-min incubation in a chromium-free medium at 37 degrees C. The results obtained indicate that hexavalent chromium compounds, which may be found in the diet, can interact directly with DNA of the mucosa of the stomach.","Genotoxicity of chromium in human gastric mucosa cells and peripheral blood lymphocytes evaluated by the single cell gel electrophoresis (comet assay) Abs: Hexavalent chromium compounds are well-recognized carcinogens. They easily penetrate the cell membrane and are reduced inside the cell to their trivalent form, which is supposed to react directly with DNA. Chromium is present in some workplaces as well as in water resources and food chain, so it can interact with the mucosa of the gastrointestinal tract. In order to elucidate the genotoxic potency of chromium in human gastric mucosa (GM) cells, the DNA-damaging effect of potassium dichromate (K2Cr2O7) was investigated using alkaline single cell gel electrophoresis (comet assay). Biopsy samples were obtained during gastroscopy from macroscopically healthy tissue of the stomach. Parallel test with human peripheral blood lymphocytes was also performed. Both types of cells were incubated at 37 degrees C with 1.6 mM of K2Cr2O7 for 1 h and after washing, were placed in a chromium-free medium to examine DNA repair. Alkaline single cell gel electrophoresis (comet assay) was used to assess DNA damage and repair. Chromium introduced a damage to DNA both in the GM cells and lymphocytes. The effect induced by K2Cr2O7 in GM cells was comparable with that caused in the lymphocytes. Treated cells were able to recover within a 60-min incubation in a chromium-free medium at 37 degrees C. The results obtained indicate that hexavalent chromium compounds, which may be found in the diet, can interact directly with DNA of the mucosa of the stomach."
1233786,Kulpa et al. 2000,"CYFRA 21-1, TPA-M, TPS, SCC-Ag and CEA in patients with squamous cell lung cancer and in chemical industry workers as a reference group","In etiology of lung cancer chemical carcinogenesis seems to be a very important factor. In the studies presented here the diagnostic usefulness of tumor markers in lung cancer was evaluated, using as a reference group workers of a chemical plant producing chromite and chromate pigments. The investigations of CYFRA 21-1, TPA-M, TPS, CEA and SCC-Ag were performed before treatment in a group of 76 squamous cell lung cancer patients in different stages of disease and in a reference group of 75 workers of the chemical company, who had been exposed to hexavalent chromium for longer than 1 year and had no clinical or radiological symptoms of lung diseases. In the squamous cell lung cancer group concentrations of all analyzed tumor markers were considered to be significantly higher than in the reference group. TPA assay demonstrated higher diagnostic performance than CYFRA 21-1 and the remaining tumor markers. At 0.95 specificity, the sensitivity of TPA was 0.79, CYFRA 21-1 -0.76, of TPS -0.29 whilst of CEA and SCC-Ag -0.31. The univariate analysis showed a significant prognostic value for clinical stages, only for CYFRA 21-1 and SCC-Ag. A significant relationship between marker level and survival was observed for CYFRA 21-1 as well as SCC-Ag levels. In a multivariate analysis CYFRA 21-1 and/or TPS remained significant predictors of survival.","CYFRA 21-1, TPA-M, TPS, SCC-Ag and CEA in patients with squamous cell lung cancer and in chemical industry workers as a reference group Abs: In etiology of lung cancer chemical carcinogenesis seems to be a very important factor. In the studies presented here the diagnostic usefulness of tumor markers in lung cancer was evaluated, using as a reference group workers of a chemical plant producing chromite and chromate pigments. The investigations of CYFRA 21-1, TPA-M, TPS, CEA and SCC-Ag were performed before treatment in a group of 76 squamous cell lung cancer patients in different stages of disease and in a reference group of 75 workers of the chemical company, who had been exposed to hexavalent chromium for longer than 1 year and had no clinical or radiological symptoms of lung diseases. In the squamous cell lung cancer group concentrations of all analyzed tumor markers were considered to be significantly higher than in the reference group. TPA assay demonstrated higher diagnostic performance than CYFRA 21-1 and the remaining tumor markers. At 0.95 specificity, the sensitivity of TPA was 0.79, CYFRA 21-1 -0.76, of TPS -0.29 whilst of CEA and SCC-Ag -0.31. The univariate analysis showed a significant prognostic value for clinical stages, only for CYFRA 21-1 and SCC-Ag. A significant relationship between marker level and survival was observed for CYFRA 21-1 as well as SCC-Ag levels. In a multivariate analysis CYFRA 21-1 and/or TPS remained significant predictors of survival."
1233784,Hadjispyrou et al. 2001,"Toxicity, bioaccumulation, and interactive effects of organotin, cadmium, and chromium on Artemia franciscana","The effects of three organotin compounds-trimethyltin chloride, dimethyltin dichloride, and dibutyltin diacetate-and two heavy metals-cadmium and hexavalent chromium-on Artemia franciscana mortality are investigated in this study. Of all the compounds tested in this work, trimethyltin chloride was, by far, the most toxic. The toxicity order for the five compounds was trimethyltin chloride &gt; potassium dichromate &gt; dimethyltin dichloride &gt; dibutyltin diacetate &gt; cadmium chloride. The big difference in toxicity between dialkyltin and trialkyltin was not accompanied by an equally big difference in bioaccumulation. At a Sn concentration in water of 10 mg/L, the bioconcentration factor was 50 for dimethyltin dichloride and 75 for trimethyltin chloride. At a Sn concentration in water of 100 mg/L, the bioconcentration factor for 6 for dimethyltin dichloride and 9 for trimethyltin chloride. The interactive effect of trimethyltin chloride and cadmium, as well as that of trimethyltin chloride and chromium, was found to be synergistic. Also found to be synergistic was the interactive effect of trimethyltin chloride with cadmium and chromium applied together.","Toxicity, bioaccumulation, and interactive effects of organotin, cadmium, and chromium on Artemia franciscana Abs: The effects of three organotin compounds-trimethyltin chloride, dimethyltin dichloride, and dibutyltin diacetate-and two heavy metals-cadmium and hexavalent chromium-on Artemia franciscana mortality are investigated in this study. Of all the compounds tested in this work, trimethyltin chloride was, by far, the most toxic. The toxicity order for the five compounds was trimethyltin chloride &gt; potassium dichromate &gt; dimethyltin dichloride &gt; dibutyltin diacetate &gt; cadmium chloride. The big difference in toxicity between dialkyltin and trialkyltin was not accompanied by an equally big difference in bioaccumulation. At a Sn concentration in water of 10 mg/L, the bioconcentration factor was 50 for dimethyltin dichloride and 75 for trimethyltin chloride. At a Sn concentration in water of 100 mg/L, the bioconcentration factor for 6 for dimethyltin dichloride and 9 for trimethyltin chloride. The interactive effect of trimethyltin chloride and cadmium, as well as that of trimethyltin chloride and chromium, was found to be synergistic. Also found to be synergistic was the interactive effect of trimethyltin chloride with cadmium and chromium applied together."
1233782,Niemelä et al. 2001,Stratification of welding fumes and grinding particles in a large factory hall equipped with displacement ventilation,"The purpose of the study was to investigate the performance of displacement ventilation in a large factory hall where large components of stainless steel for paper, pulp and chemical industries were manufactured. The performance of displacement ventilation was evaluated in terms of concentration distributions of welding fumes and grinding particles, flow field of the supply air and temperature distributions. Large differences in vertical stratification patterns between hexavalent chromium (Cr(VI)) and other particulate contaminants were observed. The concentration of Cr(VI) was notably lower in the zone of occupancy than in the upper part of the factory hall, whereas the concentrations of total airborne particles and trivalent chromium (Cr(III)) were higher in the occupied zone than in the upper zone. The stratification of Cr(VI) had the same tendency as the air temperature stratification caused by the displacement flow field.","Stratification of welding fumes and grinding particles in a large factory hall equipped with displacement ventilation Abs: The purpose of the study was to investigate the performance of displacement ventilation in a large factory hall where large components of stainless steel for paper, pulp and chemical industries were manufactured. The performance of displacement ventilation was evaluated in terms of concentration distributions of welding fumes and grinding particles, flow field of the supply air and temperature distributions. Large differences in vertical stratification patterns between hexavalent chromium (Cr(VI)) and other particulate contaminants were observed. The concentration of Cr(VI) was notably lower in the zone of occupancy than in the upper part of the factory hall, whereas the concentrations of total airborne particles and trivalent chromium (Cr(III)) were higher in the occupied zone than in the upper zone. The stratification of Cr(VI) had the same tendency as the air temperature stratification caused by the displacement flow field."
1233781,Pattanapipitpaisal et al. 2001,Chromate reduction and 16S rRNA identification of bacteria isolated from a Cr(VI)-contaminated site,"A gram-positive, hexavalent chromium [chromate: Cr(VI)]-tolerant bacterium, isolated from tannery waste from Pakistan, was identified as a Microbacterium sp. by 16S rRNA gene sequence homology. The strain (designated as MP30) reduced toxic Cr(VI) only under anaerobic conditions at the expense of acetate as the electron donor. The bacterium was able to grow aerobically in L-broth supplemented with 15 mM CrO4(2-) but then did not reduce Cr(VI). At a concentration of 2.4x10(9) cells/ml, 100 microM sodium chromate was reduced within 30 h; however, the maximum specific reduction rate was obtained at lower initial cell concentrations.","Chromate reduction and 16S rRNA identification of bacteria isolated from a Cr(VI)-contaminated site Abs: A gram-positive, hexavalent chromium [chromate: Cr(VI)]-tolerant bacterium, isolated from tannery waste from Pakistan, was identified as a Microbacterium sp. by 16S rRNA gene sequence homology. The strain (designated as MP30) reduced toxic Cr(VI) only under anaerobic conditions at the expense of acetate as the electron donor. The bacterium was able to grow aerobically in L-broth supplemented with 15 mM CrO4(2-) but then did not reduce Cr(VI). At a concentration of 2.4x10(9) cells/ml, 100 microM sodium chromate was reduced within 30 h; however, the maximum specific reduction rate was obtained at lower initial cell concentrations."
1233780,Hodges et al. 2001,Induction of DNA-strand breaks in human peripheral blood lymphocytes and A549 lung cells by sodium dichromate: association with 8-oxo-2-deoxyguanosine formation and inter-individual variability,"Hexavalent chromium [Cr(VI)] is a genotoxic carcinogen for which inhalation is a major potential route of exposure in occupational settings. In the present study, the ability of sodium dichromate to cause DNA strand breaks in three populations of cells, human whole blood cells, isolated human peripheral blood lymphocytes and cultured A549 lung epithelial cells, was investigated. Treatment with non-cytotoxic concentrations of sodium dichromate (for 1 h) resulted in a concentration-dependent increase in the number of DNA strand breaks as measured by the Comet assay. The lowest concentrations of sodium dichromate that resulted in a statistically significant (P &lt; 0.01) increase in the number of DNA strand breaks were 500, 50 and 10 microM, respectively, in these cells. The use of formamidopyrimidine glycosylase increased the sensitivity of detection of strand breaks in A549 cells 10-fold, suggesting a role for DNA base oxidation in the mechanism of dichromate-induced DNA strand breaks. In support of this hypothesis, immunocytochemistry indicated an elevation of 8-oxodeoxyguanosine in A549 cells treated with 10 and 500 microM sodium dichromate for 1 h. We also demonstrated 2.11- and 2.5-fold ranges in the level of control and dichromate (500 microM)-induced DNA strand breaks, respectively, in cells of whole blood within a group of healthy volunteers (n = 26). A statistically significant (P &lt; 0.001) positive Pearson's correlation (r = 0.606) was found between control and treated levels of DNA strand breaks, suggesting that factors responsible for relatively low levels of DNA strand breaks in untreated PBL may also offer protection against the formation of dichromate-induced DNA strand breaks.","Induction of DNA-strand breaks in human peripheral blood lymphocytes and A549 lung cells by sodium dichromate: association with 8-oxo-2-deoxyguanosine formation and inter-individual variability Abs: Hexavalent chromium [Cr(VI)] is a genotoxic carcinogen for which inhalation is a major potential route of exposure in occupational settings. In the present study, the ability of sodium dichromate to cause DNA strand breaks in three populations of cells, human whole blood cells, isolated human peripheral blood lymphocytes and cultured A549 lung epithelial cells, was investigated. Treatment with non-cytotoxic concentrations of sodium dichromate (for 1 h) resulted in a concentration-dependent increase in the number of DNA strand breaks as measured by the Comet assay. The lowest concentrations of sodium dichromate that resulted in a statistically significant (P &lt; 0.01) increase in the number of DNA strand breaks were 500, 50 and 10 microM, respectively, in these cells. The use of formamidopyrimidine glycosylase increased the sensitivity of detection of strand breaks in A549 cells 10-fold, suggesting a role for DNA base oxidation in the mechanism of dichromate-induced DNA strand breaks. In support of this hypothesis, immunocytochemistry indicated an elevation of 8-oxodeoxyguanosine in A549 cells treated with 10 and 500 microM sodium dichromate for 1 h. We also demonstrated 2.11- and 2.5-fold ranges in the level of control and dichromate (500 microM)-induced DNA strand breaks, respectively, in cells of whole blood within a group of healthy volunteers (n = 26). A statistically significant (P &lt; 0.001) positive Pearson's correlation (r = 0.606) was found between control and treated levels of DNA strand breaks, suggesting that factors responsible for relatively low levels of DNA strand breaks in untreated PBL may also offer protection against the formation of dichromate-induced DNA strand breaks."
1233779,Pritchard et al. 2001,Mechanism of apoptosis and determination of cellular fate in chromium(VI)-exposed populations of telomerase-immortalized human fibroblasts,"The cellular responses to carcinogen exposure influence cellular fate, which in turn modulates the neoplastic response. Certain hexavalent chromium [Cr(VI)] compounds are implicated as occupational respiratory carcinogens at doses that are both genotoxic and cytotoxic. We examined the mechanism of Cr(VI)-induced apoptosis in normal human fibroblasts (BJ) immortalized by human telomerase gene transfection (BJ-hTERT), and we assessed the spectrum of cumulative cellular fates [(a) regaining of replicative potential; (b) terminal growth arrest; or (c) apoptosis] for a narrow range of increasingly genotoxic doses of Cr(VI). Exposure of BJ-hTERT cells to Cr(VI) resulted in a dose-dependent increase in apoptosis that involved mitochondrial disruption as evidenced by mitochondrial membrane depolarization and cytochrome c release. The initial response to Cr(VI) exposure was inhibition of cell cycle progression. At the lowest dose tested (1 microM; 32% clonogenic survival), the cell cycle inhibition led to terminal growth arrest but no apoptosis. The fraction of terminally growth arrested cells increased as the dose was increased to 3 microM but then decreased at 4, 5, and 6 microM as apoptosis became the predominant cell fate. Our results suggest that cell populations exposed to Cr(VI) have a different spectrum of responses, depending on the extent of DNA damage, and that the regaining of replicative potential after relatively higher genotoxic exposures may be attributable to either escape from, or resistance to, terminal growth arrest or apoptosis.","Mechanism of apoptosis and determination of cellular fate in chromium(VI)-exposed populations of telomerase-immortalized human fibroblasts Abs: The cellular responses to carcinogen exposure influence cellular fate, which in turn modulates the neoplastic response. Certain hexavalent chromium [Cr(VI)] compounds are implicated as occupational respiratory carcinogens at doses that are both genotoxic and cytotoxic. We examined the mechanism of Cr(VI)-induced apoptosis in normal human fibroblasts (BJ) immortalized by human telomerase gene transfection (BJ-hTERT), and we assessed the spectrum of cumulative cellular fates [(a) regaining of replicative potential; (b) terminal growth arrest; or (c) apoptosis] for a narrow range of increasingly genotoxic doses of Cr(VI). Exposure of BJ-hTERT cells to Cr(VI) resulted in a dose-dependent increase in apoptosis that involved mitochondrial disruption as evidenced by mitochondrial membrane depolarization and cytochrome c release. The initial response to Cr(VI) exposure was inhibition of cell cycle progression. At the lowest dose tested (1 microM; 32% clonogenic survival), the cell cycle inhibition led to terminal growth arrest but no apoptosis. The fraction of terminally growth arrested cells increased as the dose was increased to 3 microM but then decreased at 4, 5, and 6 microM as apoptosis became the predominant cell fate. Our results suggest that cell populations exposed to Cr(VI) have a different spectrum of responses, depending on the extent of DNA damage, and that the regaining of replicative potential after relatively higher genotoxic exposures may be attributable to either escape from, or resistance to, terminal growth arrest or apoptosis."
1233778,O'Brien et al. 2001,Effects of glutathione on chromium-induced DNA crosslinking and DNA polymerase arrest,"Hexavalent chromium (Cr (VI)) is reduced intracellularly to Cr (V), Cr (IV) and Cr (III) by ascorbate (Asc), cysteine and glutathione (GSH). These metabolites induce a spectrum of genomic DNA damage resulting in the inhibition of DNA replication. Our previous studies have shown that treatment of DNA with Cr (III) or Cr (VI) plus Asc results in the formation of DNA-Cr-DNA crosslinks (Cr-DDC) and guanine-specific arrests of both prokaryotic and mammalian DNA polymerases. GSH not only acts as a reductant of Cr (VI) but also becomes crosslinked to DNA by Cr, thus, the focus of the present study was to examine the role of GSH in Cr-induced DNA damage and polymerase arrests. Co-incubation of Cr (III) with plasmid DNA in the presence of GSH led to the crosslinking of GSH to DNA. GSH co-treatment with Cr (III) also led to a decrease in the degree of Cr-induced DNA interstrand crosslinks relative to Cr (III) alone, without affecting total Cr DNA binding. DNA polymerase arrests were observed following treatment of DNA with Cr (III) alone, but were markedly reduced when GSH was added to the reaction mixture. Pre-formed polymerase-arresting lesions (Cr-DDC) were not removed by subsequent addition of GSH. Treatment of DNA with Cr (VI), in the presence of GSH, resulted in crosslinking of GSH to DNA, but failed to produce detectable DNA interstrand crosslinks or polymerase arrests. The inhibitory effect of GSH on Cr-induced polymerase arrest was further confirmed in human genomic DNA using quantitative PCR (QPCR) analysis. Treatment of genomic DNA with Cr (III) resulted in a marked inhibition of the amplification of a 1.6 kb target fragment of the p53 gene by Taq polymerase. This was almost completely prevented by co-treatment with GSH and Cr (III). These results indicate that Cr-induced DNA interstrand crosslinks, and not DNA-Cr-GSH crosslinks, are the principal lesions responsible for blocking DNA replication. Moreover, the formation of DNA-Cr-GSH crosslinks may actually preclude the formation of the polymerase arresting lesions.","Effects of glutathione on chromium-induced DNA crosslinking and DNA polymerase arrest Abs: Hexavalent chromium (Cr (VI)) is reduced intracellularly to Cr (V), Cr (IV) and Cr (III) by ascorbate (Asc), cysteine and glutathione (GSH). These metabolites induce a spectrum of genomic DNA damage resulting in the inhibition of DNA replication. Our previous studies have shown that treatment of DNA with Cr (III) or Cr (VI) plus Asc results in the formation of DNA-Cr-DNA crosslinks (Cr-DDC) and guanine-specific arrests of both prokaryotic and mammalian DNA polymerases. GSH not only acts as a reductant of Cr (VI) but also becomes crosslinked to DNA by Cr, thus, the focus of the present study was to examine the role of GSH in Cr-induced DNA damage and polymerase arrests. Co-incubation of Cr (III) with plasmid DNA in the presence of GSH led to the crosslinking of GSH to DNA. GSH co-treatment with Cr (III) also led to a decrease in the degree of Cr-induced DNA interstrand crosslinks relative to Cr (III) alone, without affecting total Cr DNA binding. DNA polymerase arrests were observed following treatment of DNA with Cr (III) alone, but were markedly reduced when GSH was added to the reaction mixture. Pre-formed polymerase-arresting lesions (Cr-DDC) were not removed by subsequent addition of GSH. Treatment of DNA with Cr (VI), in the presence of GSH, resulted in crosslinking of GSH to DNA, but failed to produce detectable DNA interstrand crosslinks or polymerase arrests. The inhibitory effect of GSH on Cr-induced polymerase arrest was further confirmed in human genomic DNA using quantitative PCR (QPCR) analysis. Treatment of genomic DNA with Cr (III) resulted in a marked inhibition of the amplification of a 1.6 kb target fragment of the p53 gene by Taq polymerase. This was almost completely prevented by co-treatment with GSH and Cr (III). These results indicate that Cr-induced DNA interstrand crosslinks, and not DNA-Cr-GSH crosslinks, are the principal lesions responsible for blocking DNA replication. Moreover, the formation of DNA-Cr-GSH crosslinks may actually preclude the formation of the polymerase arresting lesions."
1233777,Gardner and  Comber 2002,Determination of trace concentrations of hexavalent chromium,"A simple and sensitive solvent extraction-atomic spectrometric technique has been developed for the determination of hexavalent chromium in fresh and saline waters. The technique is based on the reaction of chromium with diphenylcarbazide. The method has been tested on a variety of water samples over an analytical range of 0-2 microg l(-1). A limit of detection of 0.024 microg l(-1) was achieved. Spiking recoveries in the range 87-115% were achieved in river water, drinking water and marine waters.","Determination of trace concentrations of hexavalent chromium Abs: A simple and sensitive solvent extraction-atomic spectrometric technique has been developed for the determination of hexavalent chromium in fresh and saline waters. The technique is based on the reaction of chromium with diphenylcarbazide. The method has been tested on a variety of water samples over an analytical range of 0-2 microg l(-1). A limit of detection of 0.024 microg l(-1) was achieved. Spiking recoveries in the range 87-115% were achieved in river water, drinking water and marine waters."
1233776,Hodges and  Chipman 2002,Down-regulation of the DNA-repair endonuclease 8-oxo-guanine DNA glycosylase 1 (hOGG1) by sodium dichromate in cultured human A549 lung carcinoma cells,"Hexavalent chromium is a genotoxic human pulmonary carcinogen that elevates DNA oxidation, apparently through the generation of reactive DNA-damaging intermediates including Cr(V), Cr(IV) and reactive oxygen species. We tested the hypothesis that elevation of DNA oxidation may also be through inhibition of the expression of the repair glycosylase for 8-oxo deoxyguanine (hOGG1) in cultured A549 human lung epithelial cells. Treatment with sodium dichromate (0-100 microM, 16 h) resulted in a concentration-dependent decrease in the levels of OGG1 mRNA as measured by both RT-PCR and RNase protection assay. Sodium dichromate at 25 microM and above gave a marked reduction of OGG1 mRNA expression which was not seen at 1 microM and below. No effect on the expression of the apurinic endonuclease hAPE or the house-keeping gene GAPDH was observed at any of the concentrations of sodium dichromate investigated. Treatment of cells with the pro-oxidant H(2)O(2) (0-200 microM) for 16 h had no detectable effect on the levels of OGG1 mRNA or protein expression suggesting that the effect of sodium dichromate is not mediated by H(2)O(2). Western blotting demonstrated that sodium dichromate (100 microM; 16 h and &gt;25 microM; 28 h) markedly reduced levels of OGG1 protein in nuclear cell extracts. Additionally, treatment of cells with sodium dichromate (&gt;25 microM, 28 h) resulted in a concentration-dependent decrease in the ability of nuclear extracts to nick a synthetic oligonucleotide containing 8-oxo deoxyguanine (8-oxo dG). We conclude that the elevation of 8-oxo dG levels observed in A549 cells treated with sodium dichromate may be, at least in part, due to a reduced capacity to repair endogenous and hexavalent chromium-induced 8-oxo dG.","Down-regulation of the DNA-repair endonuclease 8-oxo-guanine DNA glycosylase 1 (hOGG1) by sodium dichromate in cultured human A549 lung carcinoma cells Abs: Hexavalent chromium is a genotoxic human pulmonary carcinogen that elevates DNA oxidation, apparently through the generation of reactive DNA-damaging intermediates including Cr(V), Cr(IV) and reactive oxygen species. We tested the hypothesis that elevation of DNA oxidation may also be through inhibition of the expression of the repair glycosylase for 8-oxo deoxyguanine (hOGG1) in cultured A549 human lung epithelial cells. Treatment with sodium dichromate (0-100 microM, 16 h) resulted in a concentration-dependent decrease in the levels of OGG1 mRNA as measured by both RT-PCR and RNase protection assay. Sodium dichromate at 25 microM and above gave a marked reduction of OGG1 mRNA expression which was not seen at 1 microM and below. No effect on the expression of the apurinic endonuclease hAPE or the house-keeping gene GAPDH was observed at any of the concentrations of sodium dichromate investigated. Treatment of cells with the pro-oxidant H(2)O(2) (0-200 microM) for 16 h had no detectable effect on the levels of OGG1 mRNA or protein expression suggesting that the effect of sodium dichromate is not mediated by H(2)O(2). Western blotting demonstrated that sodium dichromate (100 microM; 16 h and &gt;25 microM; 28 h) markedly reduced levels of OGG1 protein in nuclear cell extracts. Additionally, treatment of cells with sodium dichromate (&gt;25 microM, 28 h) resulted in a concentration-dependent decrease in the ability of nuclear extracts to nick a synthetic oligonucleotide containing 8-oxo deoxyguanine (8-oxo dG). We conclude that the elevation of 8-oxo dG levels observed in A549 cells treated with sodium dichromate may be, at least in part, due to a reduced capacity to repair endogenous and hexavalent chromium-induced 8-oxo dG."
1233775,Zhang et al. 2002,"Comparison of the cytotoxicity, cellular uptake, and DNA-protein crosslinks induced by potassium chromate in lymphoblast cell lines derived from three different individuals","We are trying to understand individual differences in susceptibility to chromate toxicity by comparing three different lymphoblastic cell lines derived from three different individuals. We have compared the uptake of CrO4(2-), the release of LDH from cells, the proliferation ability of the cells, and the DNA-protein crosslinks in these lymphoblastic cell lines exposed to chromate. We report here that one lymphoblastic cell line, GM0922B, appears to be considerably less sensitive than the other two cells lines to the cytotoxic effects of hexavalent chromium. The diminished sensitivity is almost twofold and can be accounted for by the decreased uptake of hexavalent chromium, which results in less lactate dehydrogenase release, and greater tolerance to chromate inhibition of cell proliferation and less DNA-protein crosslinking. This lower uptake of chromate combined with interindividual differences in extracellular Cr(VI) reducing capacity are probably the two most important determinants of genetic susceptibility to chromate toxicity.","Comparison of the cytotoxicity, cellular uptake, and DNA-protein crosslinks induced by potassium chromate in lymphoblast cell lines derived from three different individuals Abs: We are trying to understand individual differences in susceptibility to chromate toxicity by comparing three different lymphoblastic cell lines derived from three different individuals. We have compared the uptake of CrO4(2-), the release of LDH from cells, the proliferation ability of the cells, and the DNA-protein crosslinks in these lymphoblastic cell lines exposed to chromate. We report here that one lymphoblastic cell line, GM0922B, appears to be considerably less sensitive than the other two cells lines to the cytotoxic effects of hexavalent chromium. The diminished sensitivity is almost twofold and can be accounted for by the decreased uptake of hexavalent chromium, which results in less lactate dehydrogenase release, and greater tolerance to chromate inhibition of cell proliferation and less DNA-protein crosslinking. This lower uptake of chromate combined with interindividual differences in extracellular Cr(VI) reducing capacity are probably the two most important determinants of genetic susceptibility to chromate toxicity."
1233773,Viamajala et al. 2002,Chromate/nitrite interactions in Shewanella oneidensis MR-1: evidence for multiple hexavalent chromium [Cr(VI)] reduction mechanisms dependent on physiological growth conditions,"Inhibition of hexavalent chromium [Cr(VI)] reduction due to nitrate and nitrite was observed during tests with Shewanella oneidensis MR-1 (previously named Shewanella putrefaciens MR-1 and henceforth referred to as MR-1). Initial Cr(VI) reduction rates were measured at various nitrite concentrations, and a mixed inhibition kinetic model was used to determine the kinetic parameters-maximum Cr(VI) reduction rate and inhibition constant [V(max,Cr(VI)) and K(i,Cr(VI))]. Values of V(max,Cr(VI)) and K(i,Cr(VI)) obtained with MR-1 cultures grown under denitrifying conditions were observed to be significantly different from the values obtained when the cultures were grown with fumarate as the terminal electron acceptor. It was also observed that a single V(max,Cr(VI)) and K(i,Cr(VI)) did not adequately describe the inhibition kinetics of either nitrate-grown or fumarate-grown cultures. The inhibition patterns indicate that Cr(VI) reduction in MR-1 is likely not limited to a single pathway, but occurs via different mechanisms some of which are dependent on growth conditions. Inhibition of nitrite reduction due to the presence of Cr(VI) was also studied, and the kinetic parameters V(max,NO2) and K(i,NO2) were determined. It was observed that these coefficients also differed significantly between MR-1 grown under denitrifying conditions and fumarate reducing conditions. The inhibition studies suggest the involvement of nitrite reductase in Cr(VI) reduction. Because nitrite reduction is part of the anaerobic respiration process, inhibition due to Cr(VI) might be a result of interaction with the components of the anaerobic respiration pathway such as nitrite reductase. Also, differences in the degree of inhibition of nitrite reduction activity by chromate at different growth conditions suggest that the toxicity mechanism of Cr(VI) might also be dependent on the conditions of growth. Cr(VI) reduction has been shown to occur via different pathways, but to our knowledge, multiple pathways within a single organism leading to Cr(VI) reduction has not been reported previously.","Chromate/nitrite interactions in Shewanella oneidensis MR-1: evidence for multiple hexavalent chromium [Cr(VI)] reduction mechanisms dependent on physiological growth conditions Abs: Inhibition of hexavalent chromium [Cr(VI)] reduction due to nitrate and nitrite was observed during tests with Shewanella oneidensis MR-1 (previously named Shewanella putrefaciens MR-1 and henceforth referred to as MR-1). Initial Cr(VI) reduction rates were measured at various nitrite concentrations, and a mixed inhibition kinetic model was used to determine the kinetic parameters-maximum Cr(VI) reduction rate and inhibition constant [V(max,Cr(VI)) and K(i,Cr(VI))]. Values of V(max,Cr(VI)) and K(i,Cr(VI)) obtained with MR-1 cultures grown under denitrifying conditions were observed to be significantly different from the values obtained when the cultures were grown with fumarate as the terminal electron acceptor. It was also observed that a single V(max,Cr(VI)) and K(i,Cr(VI)) did not adequately describe the inhibition kinetics of either nitrate-grown or fumarate-grown cultures. The inhibition patterns indicate that Cr(VI) reduction in MR-1 is likely not limited to a single pathway, but occurs via different mechanisms some of which are dependent on growth conditions. Inhibition of nitrite reduction due to the presence of Cr(VI) was also studied, and the kinetic parameters V(max,NO2) and K(i,NO2) were determined. It was observed that these coefficients also differed significantly between MR-1 grown under denitrifying conditions and fumarate reducing conditions. The inhibition studies suggest the involvement of nitrite reductase in Cr(VI) reduction. Because nitrite reduction is part of the anaerobic respiration process, inhibition due to Cr(VI) might be a result of interaction with the components of the anaerobic respiration pathway such as nitrite reductase. Also, differences in the degree of inhibition of nitrite reduction activity by chromate at different growth conditions suggest that the toxicity mechanism of Cr(VI) might also be dependent on the conditions of growth. Cr(VI) reduction has been shown to occur via different pathways, but to our knowledge, multiple pathways within a single organism leading to Cr(VI) reduction has not been reported previously."
1233772,Dennis et al. 2002,Control of occupational exposure to hexavalent chromium and ozone in tubular wire arc-welding processes by replacement of potassium by lithium or by addition of zinc,"Hexavalent chromium [Cr(VI)] and ozone are produced in many arc-welding processes. Cr(VI) is formed when welding with chromium-containing alloys and is a suspected carcinogen. Ozone is formed by the action of ultraviolet light from the arc on oxygen and can cause severe irritation to the eyes and mucous membranes. Previous work has demonstrated that reduction of sodium and potassium in manual metal arc-welding electrodes leads to substantial reductions in Cr(VI) concentrations in the fume as well as a reduction in the fume formation rate. In this paper replacement of potassium by lithium in a tubular wire welding electrode (self-shielding flux-cored) is shown to give reductions in Cr(VI) concentrations and fume formation rates. Previous work has also demonstrated that use of a tubular wire (metal cored) containing 1% zinc can, under certain conditions, result in a reduction in Cr(VI) formation rate and in ozone concentration near the arc but with a rise in the total fume formation rate. The effects of different shield gases and different levels of zinc are examined. An experimental chromium-containing tubular wire with 1% zinc was used with the following shield gases: argon, Argoshield 5, Argoshield 20, Helishield 101, Ar + 2% CO2, Ar + 5% CO2, Ar + 1% O2 and Ar + 2% O2. The wire gave &gt; 98% reduction in Cr(VI) formation rate compared to the control wire provided the shield gas contained no oxygen. When the shield gas did contain oxygen, 1% zinc enhanced Cr(VI) formation rate, resulting in more than double the rates measured when welding with the control wire. Experiments with zinc concentrations, from 0.018 to 0.9% using Helishield 101, gave results indicating that there is an optimum zinc concentration from the point of view of Cr(VI) reduction. Implications of the use of lithium or zinc on the overall exposure risk are discussed.","Control of occupational exposure to hexavalent chromium and ozone in tubular wire arc-welding processes by replacement of potassium by lithium or by addition of zinc Abs: Hexavalent chromium [Cr(VI)] and ozone are produced in many arc-welding processes. Cr(VI) is formed when welding with chromium-containing alloys and is a suspected carcinogen. Ozone is formed by the action of ultraviolet light from the arc on oxygen and can cause severe irritation to the eyes and mucous membranes. Previous work has demonstrated that reduction of sodium and potassium in manual metal arc-welding electrodes leads to substantial reductions in Cr(VI) concentrations in the fume as well as a reduction in the fume formation rate. In this paper replacement of potassium by lithium in a tubular wire welding electrode (self-shielding flux-cored) is shown to give reductions in Cr(VI) concentrations and fume formation rates. Previous work has also demonstrated that use of a tubular wire (metal cored) containing 1% zinc can, under certain conditions, result in a reduction in Cr(VI) formation rate and in ozone concentration near the arc but with a rise in the total fume formation rate. The effects of different shield gases and different levels of zinc are examined. An experimental chromium-containing tubular wire with 1% zinc was used with the following shield gases: argon, Argoshield 5, Argoshield 20, Helishield 101, Ar + 2% CO2, Ar + 5% CO2, Ar + 1% O2 and Ar + 2% O2. The wire gave &gt; 98% reduction in Cr(VI) formation rate compared to the control wire provided the shield gas contained no oxygen. When the shield gas did contain oxygen, 1% zinc enhanced Cr(VI) formation rate, resulting in more than double the rates measured when welding with the control wire. Experiments with zinc concentrations, from 0.018 to 0.9% using Helishield 101, gave results indicating that there is an optimum zinc concentration from the point of view of Cr(VI) reduction. Implications of the use of lithium or zinc on the overall exposure risk are discussed."
1233771,Poznyak et al. 2002,Chromium toxic effect monitoring using ozonation method,"The hexavalent chromium toxicity (in vitro) to plasma, erythrocytes, and semen lipids was evaluated. The ozonation technique is suggested to realize the rapid measurements of the lipid peroxidation (LPO) by means of the double bond indexes (DB-index and DB(cell)-index) calculation. The obtained experimental results permit to conclude that it is possible to detect the chromium effect on LPO by ozonation. The DB-index and DB(cell)-index determination in the plasma, erythrocytes, and sperm can be considered as a measure of this effect. Ozonation, suggested in this work, can provide the useful preliminary information for specialists and is a quantitative, fast, inexpensive, and simple method. In view of these comments, we conclude that the suggested ozonation method can be considered as the acceptable modern technique for the chromium toxic effect monitoring in vitro.","Chromium toxic effect monitoring using ozonation method Abs: The hexavalent chromium toxicity (in vitro) to plasma, erythrocytes, and semen lipids was evaluated. The ozonation technique is suggested to realize the rapid measurements of the lipid peroxidation (LPO) by means of the double bond indexes (DB-index and DB(cell)-index) calculation. The obtained experimental results permit to conclude that it is possible to detect the chromium effect on LPO by ozonation. The DB-index and DB(cell)-index determination in the plasma, erythrocytes, and sperm can be considered as a measure of this effect. Ozonation, suggested in this work, can provide the useful preliminary information for specialists and is a quantitative, fast, inexpensive, and simple method. In view of these comments, we conclude that the suggested ozonation method can be considered as the acceptable modern technique for the chromium toxic effect monitoring in vitro."
1233770,Sabty-Daily et al. 2002,The efficiency of alkaline extraction for the recovery of hexavalent chromium (CrVI) from paint samples and the effect of sample storage on CrVI recovery,"Workplace exposures to CrVI, a human carcinogen, are significant in spraying operations of chromate-containing paints. Accurate determination of CrVI in paint aerosol air samples is important in assessing a worker's exposure to CrVI. National Institute for Occupational Safety and Health method 7604 is widely used for determining CrVI in air samples. It utilizes an alkaline extraction procedure. It was historically validated for paint aerosol samples containing 24.5 to 61.5 microg of CrVI. The literature documented potential airborne CrVI exposures greater than 61.5 microg in recent paint spraying operations. The efficiency of the alkaline method at extracting CrVI from paint samples containing 250 to 3000 microg of CrVI was determined. Paint was prepared, sampled, extracted twice and then digested. Extracts were analyzed for CrVI and digestates of the residual Cr were analyzed for total Cr. Alkaline extraction of paint samples using NIOSH method 7604 resulted in quantitative recoveries for paint samples with CrVI filter loadings from 250 to 3000 microg. A decrease in CrVI extraction efficiency was observed in samples containing &gt; 1000 microg of CrVI. A second extraction improved the recovery of CrVI in these samples. Refrigerating paint aerosol samples for up to 2 weeks did not affect their CrVI content.","The efficiency of alkaline extraction for the recovery of hexavalent chromium (CrVI) from paint samples and the effect of sample storage on CrVI recovery Abs: Workplace exposures to CrVI, a human carcinogen, are significant in spraying operations of chromate-containing paints. Accurate determination of CrVI in paint aerosol air samples is important in assessing a worker's exposure to CrVI. National Institute for Occupational Safety and Health method 7604 is widely used for determining CrVI in air samples. It utilizes an alkaline extraction procedure. It was historically validated for paint aerosol samples containing 24.5 to 61.5 microg of CrVI. The literature documented potential airborne CrVI exposures greater than 61.5 microg in recent paint spraying operations. The efficiency of the alkaline method at extracting CrVI from paint samples containing 250 to 3000 microg of CrVI was determined. Paint was prepared, sampled, extracted twice and then digested. Extracts were analyzed for CrVI and digestates of the residual Cr were analyzed for total Cr. Alkaline extraction of paint samples using NIOSH method 7604 resulted in quantitative recoveries for paint samples with CrVI filter loadings from 250 to 3000 microg. A decrease in CrVI extraction efficiency was observed in samples containing &gt; 1000 microg of CrVI. A second extraction improved the recovery of CrVI in these samples. Refrigerating paint aerosol samples for up to 2 weeks did not affect their CrVI content."
1233768,Luque-García and  Luque de Castro 2002,Continuous ultrasound-assisted extraction of hexavalent chromium from soil with or without on-line preconcentration prior to photometric monitoring,"A continuous ultrasound-assisted extractor was coupled to a photometric detector in order to obtain a fully automated approach for the determination of CrVI in soil. The use of a flow injection (FI) manifold as interface between the extractor and the photometric detector allowed the monitoring of CrVI after extraction in a continuous manner. The coloured complex formed between 1,5-diphenylcarbazide (DPC) and CrVI was used as recommended in EPA method 7196A because it is one of the most sensitive and selective reactions for CrVI determination. A preconcentration minicolumn packed with a strong anion-exchange resin was placed between the extractor and the detector, providing a more sensitive method. The linear dynamic ranges were 1-10 and 0.25-7.5 mg l-1 for the methods without (method A) and with preconcentration (method B), respectively. The limits of detection were 4.52 ng for method A and 1.23 ng for method B. Both methods were applied to a natural contaminated soil and the results obtained agreed well with those obtained by the reference EPA method 3060A. The influence of different amounts of CrIII in the samples was also studied and the results showed that the proposed methods did not disturb the original species distribution.","Continuous ultrasound-assisted extraction of hexavalent chromium from soil with or without on-line preconcentration prior to photometric monitoring Abs: A continuous ultrasound-assisted extractor was coupled to a photometric detector in order to obtain a fully automated approach for the determination of CrVI in soil. The use of a flow injection (FI) manifold as interface between the extractor and the photometric detector allowed the monitoring of CrVI after extraction in a continuous manner. The coloured complex formed between 1,5-diphenylcarbazide (DPC) and CrVI was used as recommended in EPA method 7196A because it is one of the most sensitive and selective reactions for CrVI determination. A preconcentration minicolumn packed with a strong anion-exchange resin was placed between the extractor and the detector, providing a more sensitive method. The linear dynamic ranges were 1-10 and 0.25-7.5 mg l-1 for the methods without (method A) and with preconcentration (method B), respectively. The limits of detection were 4.52 ng for method A and 1.23 ng for method B. Both methods were applied to a natural contaminated soil and the results obtained agreed well with those obtained by the reference EPA method 3060A. The influence of different amounts of CrIII in the samples was also studied and the results showed that the proposed methods did not disturb the original species distribution."
1233767,O'Brien et al. 2002,Critical role of chromium (Cr)-DNA interactions in the formation of Cr-induced polymerase arresting lesions,"The genotoxicity associated with the metabolic reduction of hexavalent chromium [Cr(VI)] is complex and can impede DNA polymerase-mediated replication in vitro. The exact biochemical nature of Cr-induced polymerase arresting lesions (PALs) is not understood, but is believed to involve the formation of Cr-DNA interstrand cross-links (ICLs). The aim of this investigation was to determine the dependence of direct Cr-DNA interactions on the development of PALs in DNA treated with trivalent Cr [Cr(III)] or with Cr(VI) in the presence of ascorbic acid (Asc), a major intracellular reductant, using an in vitro, acellular system. The formation of Cr-DNA adducts, ICLs, and PALs was maximal at Asc:Cr(VI) molar ratios of 0.5-2, but gradually decreased at higher ratios. EDTA, a Cr(III) chelator, significantly decreased Cr-DNA binding and ICL and PAL formation. Co-treatment of DNA with Cr(VI)/Asc and mannitol, a Cr(V) chelator, selectively inhibited the formation of mono/bifunctional DNA adducts and PALs produced by Cr(VI) reduction, but had no effect on Cr(III)-DNA binding or Cr(III)-induced polymerase arrest. Blocking Cr-DNA phosphate interaction by preincubation of DNA with MgCl(2) abrogated DNA binding and ICL and PAL production. DNA strand breaks and abasic sites may lead to the in vitro arrest of DNA polymerases; however, we failed to detect significant increases in the frequency of these lesions following Cr(VI)/Asc treatment. These data indicate that the bifunctional adduction of Cr to DNA phosphates (ICLs) constitutes a major PAL. Furthermore, the generation of DNA strand breaks and abasic sites by Cr(VI) reduction is insufficient to explain PALs observed in vitro.","Critical role of chromium (Cr)-DNA interactions in the formation of Cr-induced polymerase arresting lesions Abs: The genotoxicity associated with the metabolic reduction of hexavalent chromium [Cr(VI)] is complex and can impede DNA polymerase-mediated replication in vitro. The exact biochemical nature of Cr-induced polymerase arresting lesions (PALs) is not understood, but is believed to involve the formation of Cr-DNA interstrand cross-links (ICLs). The aim of this investigation was to determine the dependence of direct Cr-DNA interactions on the development of PALs in DNA treated with trivalent Cr [Cr(III)] or with Cr(VI) in the presence of ascorbic acid (Asc), a major intracellular reductant, using an in vitro, acellular system. The formation of Cr-DNA adducts, ICLs, and PALs was maximal at Asc:Cr(VI) molar ratios of 0.5-2, but gradually decreased at higher ratios. EDTA, a Cr(III) chelator, significantly decreased Cr-DNA binding and ICL and PAL formation. Co-treatment of DNA with Cr(VI)/Asc and mannitol, a Cr(V) chelator, selectively inhibited the formation of mono/bifunctional DNA adducts and PALs produced by Cr(VI) reduction, but had no effect on Cr(III)-DNA binding or Cr(III)-induced polymerase arrest. Blocking Cr-DNA phosphate interaction by preincubation of DNA with MgCl(2) abrogated DNA binding and ICL and PAL production. DNA strand breaks and abasic sites may lead to the in vitro arrest of DNA polymerases; however, we failed to detect significant increases in the frequency of these lesions following Cr(VI)/Asc treatment. These data indicate that the bifunctional adduction of Cr to DNA phosphates (ICLs) constitutes a major PAL. Furthermore, the generation of DNA strand breaks and abasic sites by Cr(VI) reduction is insufficient to explain PALs observed in vitro."
1233766,Hansen et al. 2002,Quantitative aspects of contact allergy to chromium and exposure to chrome-tanned leather,"The potential of trivalent and hexavalent chromium to induce and elicit allergic contact dermatitis and the degree of chromium exposure from leather products are reviewed. Chromium dermatitis is often due to exposure in the occupational environment, with cement being one of the most common chromium sources. However, consumer products such as chromium(III)-tanned leather products are also an important source of chromium exposure. Apart from Cr(III), which is used for tanning, leather often also contains trace amounts of Cr(VI), which is formed by oxidation of Cr(III) during the tanning process. In a recent study of the Cr(VI) content of leather products bought on the Danish market, 35% of such articles had a Cr(VI) content above the detection limit of 3 p.p.m., ranging from 3.6 p.p.m. to 14.7 p.p.m. Leachable Cr(III) was detected at levels of 430-980 p.p.m. An examination of available dose-response studies showed that exposure to occluded patch test concentrations of 7-45 p.p.m. Cr(VI) elicits a reaction in 10% of the chromium-sensitive patients. When reviewing repeated open exposure studies, it is seen that either exposure to 5 p.p.m. Cr(VI) in the presence of 1% sodium lauryl sulfate (SLS) or exposure to 10 p.p.m. Cr(VI) alone both elicit eczema in chromium-sensitive patients. The eliciting capacity of Cr(III) has not been systematically investigated but, compared to Cr(VI), much higher concentrations are needed to elicit eczema.","Quantitative aspects of contact allergy to chromium and exposure to chrome-tanned leather Abs: The potential of trivalent and hexavalent chromium to induce and elicit allergic contact dermatitis and the degree of chromium exposure from leather products are reviewed. Chromium dermatitis is often due to exposure in the occupational environment, with cement being one of the most common chromium sources. However, consumer products such as chromium(III)-tanned leather products are also an important source of chromium exposure. Apart from Cr(III), which is used for tanning, leather often also contains trace amounts of Cr(VI), which is formed by oxidation of Cr(III) during the tanning process. In a recent study of the Cr(VI) content of leather products bought on the Danish market, 35% of such articles had a Cr(VI) content above the detection limit of 3 p.p.m., ranging from 3.6 p.p.m. to 14.7 p.p.m. Leachable Cr(III) was detected at levels of 430-980 p.p.m. An examination of available dose-response studies showed that exposure to occluded patch test concentrations of 7-45 p.p.m. Cr(VI) elicits a reaction in 10% of the chromium-sensitive patients. When reviewing repeated open exposure studies, it is seen that either exposure to 5 p.p.m. Cr(VI) in the presence of 1% sodium lauryl sulfate (SLS) or exposure to 10 p.p.m. Cr(VI) alone both elicit eczema in chromium-sensitive patients. The eliciting capacity of Cr(III) has not been systematically investigated but, compared to Cr(VI), much higher concentrations are needed to elicit eczema."
1233765,Iyer et al. 2002,Role of different valence states of chromium in the elicitation of allergic contact dermatitis,"Chromium, a known contact sensitizer, is present at high levels in certain detergent bars (40-50 p.p.m.) sold in India. A concern was whether chromium present in such detergent bars could sensitize users or their use lead to the elicitation of allergic contact dermatitis. Chromium present in detergent bars was analyzed for its valence state. It was found to be trivalent [Cr (III)] and not hexavalent [Cr (VI)]. An elicitation test on normal volunteers, as well as on volunteers who were sensitive to chromium, was carried out to determine the elicitation potential of chromium (III) in the bars. Of the 48 volunteers who completed the study, 30 did not show any positive response to either potassium dichromate, the positive control, or the detergent bar containing chromium (III). 18 volunteers who were identified as chromium-sensitive showed a positive response to potassium dichromate but not to the detergent bar containing trivalent chromium. This study clearly showed that the detergent bar with 40-50 p.p.m. of trivalent chromium did not elicit any allergic contact dermatitis even in individuals known to be chromium-sensitive. Hexavalent chromium (potassium dichromate) did however, elicit allergic contact dermatitis in these subjects.","Role of different valence states of chromium in the elicitation of allergic contact dermatitis Abs: Chromium, a known contact sensitizer, is present at high levels in certain detergent bars (40-50 p.p.m.) sold in India. A concern was whether chromium present in such detergent bars could sensitize users or their use lead to the elicitation of allergic contact dermatitis. Chromium present in detergent bars was analyzed for its valence state. It was found to be trivalent [Cr (III)] and not hexavalent [Cr (VI)]. An elicitation test on normal volunteers, as well as on volunteers who were sensitive to chromium, was carried out to determine the elicitation potential of chromium (III) in the bars. Of the 48 volunteers who completed the study, 30 did not show any positive response to either potassium dichromate, the positive control, or the detergent bar containing chromium (III). 18 volunteers who were identified as chromium-sensitive showed a positive response to potassium dichromate but not to the detergent bar containing trivalent chromium. This study clearly showed that the detergent bar with 40-50 p.p.m. of trivalent chromium did not elicit any allergic contact dermatitis even in individuals known to be chromium-sensitive. Hexavalent chromium (potassium dichromate) did however, elicit allergic contact dermatitis in these subjects."
1233764,Enander et al. 2002,Chemical characterization of sanding dust and methylene chloride usage in automotive refinishing: implications for occupational and environmental health,"Surface preparation activities conducted during automotive refinishing present several potential human health and environmental risks. This study examines the chemical composition of vehicle sanding dust and the prevalence of methylene chloride use as a basis for evaluating potential chemical exposures in the work environment, fugitive environmental releases, and take-home toxics. This article reports on the findings of (1) a statewide technology and work practices survey of 353 licensed auto body shops and (2) laboratory analyses of sanding dust representing more than 200 vehicles, 10 commercial body filler compounds, and work shirts worn during vehicle sanding while using nonventilated equipment. Survey data revealed that the majority of shops (78%) do not use ventilated sanding equipment, that most workers (55%) take their work clothes and shoes home at the end of the workday, and that 17% of the respondents used a methylene chloride-based paint stripper as an adjunct to mechanical sanding. Laboratory results showed that Pb, As, Cr, Mn, and Ni were present in the sanding dust at every facility tested. Lead concentrations in sanding dust were found to be highest at facilities that performed complete vehicle refinishing (range 770 to 7300 ppm) and at a collision repair shop that used a high-lead content body filler compound (1800 ppm). Hexavalent chromium also was found in two vocational high school paint dust samples at concentrations of 54 and 710 ppm. When total lead and chromium concentrations reached 7300 and 2300 ppm, respectively, facility sanding dust samples failed the U.S. Environmental Protection Agency's Toxicity Characteristic Leaching Procedure for hazardous waste. Metals found in the sanding dust also were present on the work shirts of technicians-ranging from 0.06 (Cd) to 81 (Mg) microg/inch2 of cloth-who sanded on paint without ventilated equipment. Results suggest that sanding dust and methylene chloride paint strippers used in vehicle resurfacing operations pose a potential hazard to human health and the environment.","Chemical characterization of sanding dust and methylene chloride usage in automotive refinishing: implications for occupational and environmental health Abs: Surface preparation activities conducted during automotive refinishing present several potential human health and environmental risks. This study examines the chemical composition of vehicle sanding dust and the prevalence of methylene chloride use as a basis for evaluating potential chemical exposures in the work environment, fugitive environmental releases, and take-home toxics. This article reports on the findings of (1) a statewide technology and work practices survey of 353 licensed auto body shops and (2) laboratory analyses of sanding dust representing more than 200 vehicles, 10 commercial body filler compounds, and work shirts worn during vehicle sanding while using nonventilated equipment. Survey data revealed that the majority of shops (78%) do not use ventilated sanding equipment, that most workers (55%) take their work clothes and shoes home at the end of the workday, and that 17% of the respondents used a methylene chloride-based paint stripper as an adjunct to mechanical sanding. Laboratory results showed that Pb, As, Cr, Mn, and Ni were present in the sanding dust at every facility tested. Lead concentrations in sanding dust were found to be highest at facilities that performed complete vehicle refinishing (range 770 to 7300 ppm) and at a collision repair shop that used a high-lead content body filler compound (1800 ppm). Hexavalent chromium also was found in two vocational high school paint dust samples at concentrations of 54 and 710 ppm. When total lead and chromium concentrations reached 7300 and 2300 ppm, respectively, facility sanding dust samples failed the U.S. Environmental Protection Agency's Toxicity Characteristic Leaching Procedure for hazardous waste. Metals found in the sanding dust also were present on the work shirts of technicians-ranging from 0.06 (Cd) to 81 (Mg) microg/inch2 of cloth-who sanded on paint without ventilated equipment. Results suggest that sanding dust and methylene chloride paint strippers used in vehicle resurfacing operations pose a potential hazard to human health and the environment."
1233763,Yazzie et al. 2003,Uranyl acetate causes DNA single strand breaks in vitro in the presence of ascorbate (vitamin C),"Uranium is a radioactive heavy metal with isotopes that decay on the geological time scale. People are exposed to uranium through uranium mining, processing, the resulting mine tailings, and the use of depleted uranium in the military. Acute exposures to uranium are chemically toxic to the kidney; however, little is known about chronic exposures, for example, if there is a direct chemical genotoxicity of uranium. The hypothesis that is being tested in the current work is that hexavalent uranium, as uranyl ion, may have a chemical genotoxicity similar to that of hexavalent chromium. In the current study, reactions of uranyl acetate (UA) and ascorbate (vitamin C) were observed to produce plasmid relaxation in pBluescript DNA. DNA strand breaks increased with increasing concentrations of a 1:1 reaction of UA and ascorbate but were not affected by increasing the ratio of ascorbate. Plasmid relaxation was inhibited by coincubation of reactions with catalase but not by coincubation with the radical scavengers mannitol, sodium azide, or 5,5-dimethyl-1-pyrroline-N-oxide. Reactions of UA and ascorbate monitored by (1)H NMR spectroscopy showed formation of a uranyl ascorbate complex, with no evidence of a dehydroascorbate product. A previous study inferred that hydroxyl radical formation was responsible for oxidative DNA damage in the presence of reactions of uranyl ion, hydrogen peroxide, and ascorbate [Miller et al. (2002) J. Bioinorg. Chem. 91, 246-252]. Current results, in the absence of added hydrogen peroxide, were not completely consistent with the interpretation that strand breaks were produced by a Fenton type generation of reactive oxygen species. Data were also consistent with the interpretation that a uranyl ascorbate complex was catalyzing hydrolysis of the DNA-phosphate backbone, in a manner similar to that known for the lanthanides. These data suggest that uranium may be directly genotoxic and may, like chromium, react with DNA by more than one pathway.","Uranyl acetate causes DNA single strand breaks in vitro in the presence of ascorbate (vitamin C) Abs: Uranium is a radioactive heavy metal with isotopes that decay on the geological time scale. People are exposed to uranium through uranium mining, processing, the resulting mine tailings, and the use of depleted uranium in the military. Acute exposures to uranium are chemically toxic to the kidney; however, little is known about chronic exposures, for example, if there is a direct chemical genotoxicity of uranium. The hypothesis that is being tested in the current work is that hexavalent uranium, as uranyl ion, may have a chemical genotoxicity similar to that of hexavalent chromium. In the current study, reactions of uranyl acetate (UA) and ascorbate (vitamin C) were observed to produce plasmid relaxation in pBluescript DNA. DNA strand breaks increased with increasing concentrations of a 1:1 reaction of UA and ascorbate but were not affected by increasing the ratio of ascorbate. Plasmid relaxation was inhibited by coincubation of reactions with catalase but not by coincubation with the radical scavengers mannitol, sodium azide, or 5,5-dimethyl-1-pyrroline-N-oxide. Reactions of UA and ascorbate monitored by (1)H NMR spectroscopy showed formation of a uranyl ascorbate complex, with no evidence of a dehydroascorbate product. A previous study inferred that hydroxyl radical formation was responsible for oxidative DNA damage in the presence of reactions of uranyl ion, hydrogen peroxide, and ascorbate [Miller et al. (2002) J. Bioinorg. Chem. 91, 246-252]. Current results, in the absence of added hydrogen peroxide, were not completely consistent with the interpretation that strand breaks were produced by a Fenton type generation of reactive oxygen species. Data were also consistent with the interpretation that a uranyl ascorbate complex was catalyzing hydrolysis of the DNA-phosphate backbone, in a manner similar to that known for the lanthanides. These data suggest that uranium may be directly genotoxic and may, like chromium, react with DNA by more than one pathway."
1233762,Ha et al. 2003,Chromium (VI) activates ataxia telangiectasia mutated (ATM) protein. Requirement of ATM for both apoptosis and recovery from terminal growth arrest,"The ataxia telangiectasia mutated (ATM) protein plays a central role in early stages of DNA double strand break (DSB) detection and controls cellular responses to this damage. Although hypersensitive to ionizing radiation-induced clonogenic lethality, ataxia telangiectasia cells are paradoxically deficient in their ability to undergo ionizing radiation-induced apoptosis. This contradiction illustrates the complexity of the central role of ATM in DNA damage response and the need for further understanding. Certain hexavalent chromium (Cr(VI)) compounds are implicated as occupational respiratory carcinogens at doses that are both genotoxic and cytotoxic. Cr(VI) induces a broad spectrum of DNA damage, but Cr(VI)-induced DSBs have not been reported. Here, we examined the role of ATM in the cellular response to Cr(VI) and found that Cr(VI) activates ATM. We also show that physiological targets of ATM, p53 Ser-15 and Chk2 Thr-68, were phosphorylated by Cr(VI) exposure in an ATM-dependent fashion. We found that ATM-/- cells were markedly resistant to Cr(VI)-induced apoptosis but considerably more sensitive to Cr(VI)-induced clonogenic lethality than wild type cells, indicating that resistance to Cr(VI)-induced apoptosis did not confer a selective survival advantage. However, analysis of long term growth arrest revealed a striking difference: ATM-/- cells were markedly less able to recover from Cr(VI)-induced growth arrest. This indicates that terminal growth arrest is the fate of these apoptosis-resistant cells. In summary, ATM is involved in cellular response to a complex genotoxin that may not directly induce DSBs. Our data suggest that ATM is a major signal initiator for genotoxin-induced apoptosis but, paradoxically, also contributes to maintenance of cell survival by facilitating recovery/escape from terminal growth arrest. The results also strongly suggest that terminal growth arrest is not merely an extended or even irreversible form of checkpoint arrest, but instead an independent and unique cell fate pathway.","Chromium (VI) activates ataxia telangiectasia mutated (ATM) protein. Requirement of ATM for both apoptosis and recovery from terminal growth arrest Abs: The ataxia telangiectasia mutated (ATM) protein plays a central role in early stages of DNA double strand break (DSB) detection and controls cellular responses to this damage. Although hypersensitive to ionizing radiation-induced clonogenic lethality, ataxia telangiectasia cells are paradoxically deficient in their ability to undergo ionizing radiation-induced apoptosis. This contradiction illustrates the complexity of the central role of ATM in DNA damage response and the need for further understanding. Certain hexavalent chromium (Cr(VI)) compounds are implicated as occupational respiratory carcinogens at doses that are both genotoxic and cytotoxic. Cr(VI) induces a broad spectrum of DNA damage, but Cr(VI)-induced DSBs have not been reported. Here, we examined the role of ATM in the cellular response to Cr(VI) and found that Cr(VI) activates ATM. We also show that physiological targets of ATM, p53 Ser-15 and Chk2 Thr-68, were phosphorylated by Cr(VI) exposure in an ATM-dependent fashion. We found that ATM-/- cells were markedly resistant to Cr(VI)-induced apoptosis but considerably more sensitive to Cr(VI)-induced clonogenic lethality than wild type cells, indicating that resistance to Cr(VI)-induced apoptosis did not confer a selective survival advantage. However, analysis of long term growth arrest revealed a striking difference: ATM-/- cells were markedly less able to recover from Cr(VI)-induced growth arrest. This indicates that terminal growth arrest is the fate of these apoptosis-resistant cells. In summary, ATM is involved in cellular response to a complex genotoxin that may not directly induce DSBs. Our data suggest that ATM is a major signal initiator for genotoxin-induced apoptosis but, paradoxically, also contributes to maintenance of cell survival by facilitating recovery/escape from terminal growth arrest. The results also strongly suggest that terminal growth arrest is not merely an extended or even irreversible form of checkpoint arrest, but instead an independent and unique cell fate pathway."
1233761,Carlton 2003,The impact of a change to inhalable occupational exposure limits: strontium chromate exposure in the U.S. Air Force,"The American Conference of Governmental Industrial Hygienists has announced its intention to replace all total particulate threshold limit values (TLVs) with size-selective TLVs. Because the U.S. Air Force has adopted the TLVs as its occupational exposure limits, the impact of this change is of interest, specifically for hexavalent chromium. This article reviews historical strontium chromate sampling data in the Air Force and the impact of its reinterpretation in comparison to an inhalable TLV. Based on the measured conversion factor between the 37-mm cassette and the IOM inhalable sampler, inhalable strontium chromate exposures will continue to exceed the TLV during all aircraft priming and most sanding procedures. In addition, inhalable exposures are expected to exceed 1000 times the TLV, greater than the highest currently assigned protection factor for airline respirators, during 25% of priming procedures. Without a change in the value of the current TLV time-weighted average of 0.5 microg/m(3), the Air Force will need to reduce strontium chromate levels, either by incorporating work practices that decrease worker productivity or considering a change to nonchromated primers.","The impact of a change to inhalable occupational exposure limits: strontium chromate exposure in the U.S. Air Force Abs: The American Conference of Governmental Industrial Hygienists has announced its intention to replace all total particulate threshold limit values (TLVs) with size-selective TLVs. Because the U.S. Air Force has adopted the TLVs as its occupational exposure limits, the impact of this change is of interest, specifically for hexavalent chromium. This article reviews historical strontium chromate sampling data in the Air Force and the impact of its reinterpretation in comparison to an inhalable TLV. Based on the measured conversion factor between the 37-mm cassette and the IOM inhalable sampler, inhalable strontium chromate exposures will continue to exceed the TLV during all aircraft priming and most sanding procedures. In addition, inhalable exposures are expected to exceed 1000 times the TLV, greater than the highest currently assigned protection factor for airline respirators, during 25% of priming procedures. Without a change in the value of the current TLV time-weighted average of 0.5 microg/m(3), the Air Force will need to reduce strontium chromate levels, either by incorporating work practices that decrease worker productivity or considering a change to nonchromated primers."
1233760,Partanen et al. 2003,Workplace carcinogen and pesticide exposures in Costa Rica,"The CAREX data system converts national workforce volumes and proportions of workers exposed to workplace carcinogens into numbers of exposed in 55 industrial categories. CAREX was adapted for Costa Rica for 27 carcinogens and seven groups of pesticides. Widespread workplace carcinogens in the 1.3 million workforce of Costa Rica are solar radiation (333,000 workers), diesel engine exhaust (278,000), environmental tobacco smoke (71,000), hexavalent chromium compounds (55,000), benzene (52,000), wood dust (32,000), silica dust (27,000), lead and inorganic lead compounds (19,000), and polycyclic aromatic compounds (17,000). The most ubiquitous pesticides were paraquat and diquat (175,000), mancozeb, maneb, and zineb (49,000), chlorothalonil (38,000), benomyl (19,000), and chlorophenoxy herbicides (11,000). Among women, formaldehyde, radon, and methylene chloride overrode pesticides, chromium, wood dust, and silica dust in numbers of exposed. High-risk sectors included agriculture, construction, personal and household services, land and water transport and allied services, pottery and similar industries, woodworks, mining, forestry and logging, fishing, manufacturing of electrical machinery, and bar and restaurant personnel.","Workplace carcinogen and pesticide exposures in Costa Rica Abs: The CAREX data system converts national workforce volumes and proportions of workers exposed to workplace carcinogens into numbers of exposed in 55 industrial categories. CAREX was adapted for Costa Rica for 27 carcinogens and seven groups of pesticides. Widespread workplace carcinogens in the 1.3 million workforce of Costa Rica are solar radiation (333,000 workers), diesel engine exhaust (278,000), environmental tobacco smoke (71,000), hexavalent chromium compounds (55,000), benzene (52,000), wood dust (32,000), silica dust (27,000), lead and inorganic lead compounds (19,000), and polycyclic aromatic compounds (17,000). The most ubiquitous pesticides were paraquat and diquat (175,000), mancozeb, maneb, and zineb (49,000), chlorothalonil (38,000), benomyl (19,000), and chlorophenoxy herbicides (11,000). Among women, formaldehyde, radon, and methylene chloride overrode pesticides, chromium, wood dust, and silica dust in numbers of exposed. High-risk sectors included agriculture, construction, personal and household services, land and water transport and allied services, pottery and similar industries, woodworks, mining, forestry and logging, fishing, manufacturing of electrical machinery, and bar and restaurant personnel."
1233759,Seishima et al. 2003,Cellular phone dermatitis with chromate allergy,"<strong>BACKGROUND: </strong>A patient with allergic contact dermatitis caused by hexavalent chromium plating on a cellular phone has already been reported.<br /><br /><strong>OBJECTIVES: </strong>This study described the clinical characteristics and results of patch tests in 8 patients with contact dermatitis possibly caused by handling a cellular phone.<br /><br /><strong>PATIENTS: </strong>The 8 patients were 4 males and 4 females aged from 14 to 54 years. They each noticed skin eruptions after 9-25 days of using a cellular phone. All patients had erythema, and 7 had papules on the hemilateral auricle or in the preauricular region. Three of 8 patients had a history of metal allergy. Chromate, aluminium and acrylnitrile-butadiene-styrene copolymer were used as plating on the cellular phones used by these patients.<br /><br /><strong>METHODS: </strong>Closed patch tests and photopatch tests were performed using metal standard antigens.<br /><br /><strong>RESULTS: </strong>The patch test was positive for 0.5, 0.1 and 0.05% potassium dichromate in all 8 patients. The photopatch test showed the same results. One patient was positive for 2% cobalt chloride and one for 5% nickel sulfate.<br /><br /><strong>CONCLUSION: </strong>It is important to consider the possibility of contact dermatitis due to a cellular phone, possibly caused by chromate, when the patients have erythema and papules on the hemilateral auricle or in the preauricular region.","Cellular phone dermatitis with chromate allergy Abs: <strong>BACKGROUND: </strong>A patient with allergic contact dermatitis caused by hexavalent chromium plating on a cellular phone has already been reported.<br /><br /><strong>OBJECTIVES: </strong>This study described the clinical characteristics and results of patch tests in 8 patients with contact dermatitis possibly caused by handling a cellular phone.<br /><br /><strong>PATIENTS: </strong>The 8 patients were 4 males and 4 females aged from 14 to 54 years. They each noticed skin eruptions after 9-25 days of using a cellular phone. All patients had erythema, and 7 had papules on the hemilateral auricle or in the preauricular region. Three of 8 patients had a history of metal allergy. Chromate, aluminium and acrylnitrile-butadiene-styrene copolymer were used as plating on the cellular phones used by these patients.<br /><br /><strong>METHODS: </strong>Closed patch tests and photopatch tests were performed using metal standard antigens.<br /><br /><strong>RESULTS: </strong>The patch test was positive for 0.5, 0.1 and 0.05% potassium dichromate in all 8 patients. The photopatch test showed the same results. One patient was positive for 2% cobalt chloride and one for 5% nickel sulfate.<br /><br /><strong>CONCLUSION: </strong>It is important to consider the possibility of contact dermatitis due to a cellular phone, possibly caused by chromate, when the patients have erythema and papules on the hemilateral auricle or in the preauricular region."
1233757,Pillay et al. 2003,Ageing of chromium(III)-bearing slag and its relation to the atmospheric oxidation of solid chromium(III)-oxide in the presence of calcium oxide,"Slag arising in ferrochromium and stainless steel production is known to contain residual levels of trivalent chromium. As the chromium is normally bound in the slag matrix in various silicate or spinel phases, and hence not easily mobilised, utilisation or controlled disposal of such slag is generally considered unproblematic. Experimental test work with a number of slag materials indicates, however, that very gradual oxidation of trivalent to hexavalent chromium does occur when the slag is exposed to atmospheric oxygen, rendering a quantifiable but small portion of chromium in this much more mobile and toxic form. Mechanisms and rates of the oxidation reaction were investigated in a number of long-term studies using both original slag materials and artificial mixes of chromium and calcium oxides. Powders of these materials, some of them rolled into balls, were left to age under different conditions for periods of up to 12 months. In the slag samples, which contained between 1 and 3 wt.% chromium, 1000-10000 microg Cr(VI) were found per gram of chromium within 6-9 months of exposure to an ambient atmosphere. The rate of the oxidation reaction decreased exponentially, and the reaction could generally be said to have ceased within 12 months. In mixtures of calcium and chromium oxides the oxidation reaction is presumed to occur at the boundaries between chromium oxide and calcium oxide phases through diffusion of oxygen along the grain boundaries and of Cr(3+) across the boundaries, resulting in the formation of calcium chromate. In the slags, where calcium and chromium oxide can form a solid solution, the oxidation is likely to occur at the exposed surface of grains containing this solution.","Ageing of chromium(III)-bearing slag and its relation to the atmospheric oxidation of solid chromium(III)-oxide in the presence of calcium oxide Abs: Slag arising in ferrochromium and stainless steel production is known to contain residual levels of trivalent chromium. As the chromium is normally bound in the slag matrix in various silicate or spinel phases, and hence not easily mobilised, utilisation or controlled disposal of such slag is generally considered unproblematic. Experimental test work with a number of slag materials indicates, however, that very gradual oxidation of trivalent to hexavalent chromium does occur when the slag is exposed to atmospheric oxygen, rendering a quantifiable but small portion of chromium in this much more mobile and toxic form. Mechanisms and rates of the oxidation reaction were investigated in a number of long-term studies using both original slag materials and artificial mixes of chromium and calcium oxides. Powders of these materials, some of them rolled into balls, were left to age under different conditions for periods of up to 12 months. In the slag samples, which contained between 1 and 3 wt.% chromium, 1000-10000 microg Cr(VI) were found per gram of chromium within 6-9 months of exposure to an ambient atmosphere. The rate of the oxidation reaction decreased exponentially, and the reaction could generally be said to have ceased within 12 months. In mixtures of calcium and chromium oxides the oxidation reaction is presumed to occur at the boundaries between chromium oxide and calcium oxide phases through diffusion of oxygen along the grain boundaries and of Cr(3+) across the boundaries, resulting in the formation of calcium chromate. In the slags, where calcium and chromium oxide can form a solid solution, the oxidation is likely to occur at the exposed surface of grains containing this solution."
1233756,Cheung and  Gu 2003,Reduction of chromate (CrO4(2-)) by an enrichment consortium and an isolate of marine sulfate-reducing bacteria,"An enrichment consortium and an isolate (isolate TKW) of sulfate-reducing bacteria (SRB) have been obtained from metal-contaminated marine sediments of Tokwawan, Hong Kong SAR. These bacteria are capable of reducing highly toxic and soluble hexavalent chromium (Cr6+) enzymatically into less toxic and insoluble trivalent chromium (Cr3+) under anaerobic conditions. The enrichment consortium almost completely (98.5%) reduced 0.6 mM Cr6+ in 168 h and the rate of reduction was 0.5 g (Cr6+) g(protein)(-1)h(-1). In comparison, with Cr6+ as the sole electron acceptor (as a surrogate for SO4(2-)), isolate TKW reduced 94.5% of the initially added Cr6+ (0.36 mM) in 288 h, with the rate of 0.26 g (Cr6+) g(protein)(-1)h(-1). Adsorption by these bacteria was not the major mechanism contributing to the transformation or removal of Cr6+. The biomass and Cr3+ in the cultures increased simultaneously with the reduction of Cr6+. These indigenous SRB might have potential application in bioremediation of metal contaminated sediments.","Reduction of chromate (CrO4(2-)) by an enrichment consortium and an isolate of marine sulfate-reducing bacteria Abs: An enrichment consortium and an isolate (isolate TKW) of sulfate-reducing bacteria (SRB) have been obtained from metal-contaminated marine sediments of Tokwawan, Hong Kong SAR. These bacteria are capable of reducing highly toxic and soluble hexavalent chromium (Cr6+) enzymatically into less toxic and insoluble trivalent chromium (Cr3+) under anaerobic conditions. The enrichment consortium almost completely (98.5%) reduced 0.6 mM Cr6+ in 168 h and the rate of reduction was 0.5 g (Cr6+) g(protein)(-1)h(-1). In comparison, with Cr6+ as the sole electron acceptor (as a surrogate for SO4(2-)), isolate TKW reduced 94.5% of the initially added Cr6+ (0.36 mM) in 288 h, with the rate of 0.26 g (Cr6+) g(protein)(-1)h(-1). Adsorption by these bacteria was not the major mechanism contributing to the transformation or removal of Cr6+. The biomass and Cr3+ in the cultures increased simultaneously with the reduction of Cr6+. These indigenous SRB might have potential application in bioremediation of metal contaminated sediments."
1233755,Racek 2003,[Chromium as an essential element],"Chromium was known for many years to be an element causing allergic reactions and having neurotoxic and carcinogenic effects. These effects can be observed especially in the case of hexavalent chromium. Only a little more than four decades ago trivalent chromium has been known as an essential element with relation to glycide and lipid metabolism. And only during several last years this chromium function has been revealed on a molecular level. After absorption in the gastrointestinal tract, chromium is most likely transported to cells bound to the plasma protein transferrin. Insulin initiates chromium transport into the cells where it is bound to the oligopeptide apochromodulin. This oligopeptide combined with four chromium(III) atoms forms chromodulin, which is important for amplifying the insulin signalling effect. After binding to insulin-activated receptor, chromodulin increases tyrosine kinase activity by one order. This enzyme forms a part of intracellular portion of insulin receptor. Chromium supplementation in people with chromium deficiency can improve glucose tolerance and some lipid metabolism parameters. The supplementation is indicated in persons with impaired glucose tolerance both in preclinical and manifested stadium of type 2 diabetes mellitus where increased lost of chromium in urine was documented. In these patients, chromium deficiency can participate in insulin resistance and hyperlipidaemia. Chromium is usually applied in the form of organic compounds: yeast extract or chromium(III) picolinate. Cr(III) picolinate can be reduced to compounds of Cr(II) in the cells which can then produce free hydroxyl radical in the so called Fenton reaction.","[Chromium as an essential element] Abs: Chromium was known for many years to be an element causing allergic reactions and having neurotoxic and carcinogenic effects. These effects can be observed especially in the case of hexavalent chromium. Only a little more than four decades ago trivalent chromium has been known as an essential element with relation to glycide and lipid metabolism. And only during several last years this chromium function has been revealed on a molecular level. After absorption in the gastrointestinal tract, chromium is most likely transported to cells bound to the plasma protein transferrin. Insulin initiates chromium transport into the cells where it is bound to the oligopeptide apochromodulin. This oligopeptide combined with four chromium(III) atoms forms chromodulin, which is important for amplifying the insulin signalling effect. After binding to insulin-activated receptor, chromodulin increases tyrosine kinase activity by one order. This enzyme forms a part of intracellular portion of insulin receptor. Chromium supplementation in people with chromium deficiency can improve glucose tolerance and some lipid metabolism parameters. The supplementation is indicated in persons with impaired glucose tolerance both in preclinical and manifested stadium of type 2 diabetes mellitus where increased lost of chromium in urine was documented. In these patients, chromium deficiency can participate in insulin resistance and hyperlipidaemia. Chromium is usually applied in the form of organic compounds: yeast extract or chromium(III) picolinate. Cr(III) picolinate can be reduced to compounds of Cr(II) in the cells which can then produce free hydroxyl radical in the so called Fenton reaction."
1233753,Shrivastava et al. 2003,Various cells of the immune system and intestine differ in their capacity to reduce hexavalent chromium,"The cells of the immune system form a strong line of defence against foreign substances. The present study was undertaken to investigate the capacity of different cells of Wistar rats to reduce potentially carcinogenic hexavalent chromium (Cr-VI) into less toxic trivalent chromium in vitro. 5 x 10(6) cells were incubated with 10 or 25 microg ml(-1) of Cr (VI) in the form of K2Cr2O7 at 37 degrees C in the presence of 5% CO2 in air. At various time periods the remaining amount of Cr (VI) was measured and the percentage of Cr (VI) reduced was calculated. Among the single cell suspensions from the splenic cells a peak reduction of 55% was observed with the total spleen cells, 40% with the B-lymphocyte-enriched subpopulation, 10% with T-lymphocytes and 24% with the macrophages. The reduction by splenic and peritoneal macrophages was similar. Total thymocytes reduced 54% of the Cr (VI). Since the most common route of entry of chromium is through drinking water and food, intestinal cells were also investigated. Among the intestinal cells the maximum reduction of 100% (of 10 microg ml(-1)) was observed with the upper villus cells and 72% with the middle villus cells while reduction was the least (4%) with the crypt cells. The reduction in the intestinal loop in situ was 100%. The time taken by each cell type for the peak reduction to Cr (VI) was markedly different. The findings thus show that the capacity of different cells in the body differs vastly in their capacity and time taken to reduce hexavalent chromium. The most efficient handling of Cr (VI) by the intestine, due to the presence of a variety of cells and bacteria, protects the body from its adverse effects.","Various cells of the immune system and intestine differ in their capacity to reduce hexavalent chromium Abs: The cells of the immune system form a strong line of defence against foreign substances. The present study was undertaken to investigate the capacity of different cells of Wistar rats to reduce potentially carcinogenic hexavalent chromium (Cr-VI) into less toxic trivalent chromium in vitro. 5 x 10(6) cells were incubated with 10 or 25 microg ml(-1) of Cr (VI) in the form of K2Cr2O7 at 37 degrees C in the presence of 5% CO2 in air. At various time periods the remaining amount of Cr (VI) was measured and the percentage of Cr (VI) reduced was calculated. Among the single cell suspensions from the splenic cells a peak reduction of 55% was observed with the total spleen cells, 40% with the B-lymphocyte-enriched subpopulation, 10% with T-lymphocytes and 24% with the macrophages. The reduction by splenic and peritoneal macrophages was similar. Total thymocytes reduced 54% of the Cr (VI). Since the most common route of entry of chromium is through drinking water and food, intestinal cells were also investigated. Among the intestinal cells the maximum reduction of 100% (of 10 microg ml(-1)) was observed with the upper villus cells and 72% with the middle villus cells while reduction was the least (4%) with the crypt cells. The reduction in the intestinal loop in situ was 100%. The time taken by each cell type for the peak reduction to Cr (VI) was markedly different. The findings thus show that the capacity of different cells in the body differs vastly in their capacity and time taken to reduce hexavalent chromium. The most efficient handling of Cr (VI) by the intestine, due to the presence of a variety of cells and bacteria, protects the body from its adverse effects."
1233752,de la Sienra et al. 2003,Potassium dichromate increases the micronucleus frequency in the crayfish Procambarus clarkii,"The assessment of biological effects on aquatic vertebrate and invertebrate species is frequently employed to monitor water pollution because it provides meaningful information on bioavailability and effective concentration levels. Of special concern are genotoxic agents that induce DNA alterations at subtoxic exposure levels. With the objective of developing a field-assay for the detection of genotoxic pollutants in water, we investigated the effects of hexavalent chromium in the haemolymph cells of Procambarus clarkii using the micronuclei (MN) test. The frequency of micronucleated cells significantly correlated with the amount of potassium dichromate in water and with the amount of chromium found in gills.","Potassium dichromate increases the micronucleus frequency in the crayfish Procambarus clarkii Abs: The assessment of biological effects on aquatic vertebrate and invertebrate species is frequently employed to monitor water pollution because it provides meaningful information on bioavailability and effective concentration levels. Of special concern are genotoxic agents that induce DNA alterations at subtoxic exposure levels. With the objective of developing a field-assay for the detection of genotoxic pollutants in water, we investigated the effects of hexavalent chromium in the haemolymph cells of Procambarus clarkii using the micronuclei (MN) test. The frequency of micronucleated cells significantly correlated with the amount of potassium dichromate in water and with the amount of chromium found in gills."
1233751,Séby et al. 2003,"Development of analytical procedures for determination of total chromium by quadrupole ICP-MS and high-resolution ICP-MS, and hexavalent chromium by HPLC-ICP-MS, in different materials used in the automotive industry","A European directive was recently adopted limiting the use of hazardous substances such as Pb, Hg, Cd, and Cr(VI) in vehicle manufacturing. From July 2003 a maximum of 2 g Cr(VI) will be authorised per vehicle in corrosion-preventing coatings of key components. As no standardised procedures are available to check if produced vehicles are in agreement with this directive, the objective of this work was to develop analytical procedures for total chromium and Cr(VI) determination in these materials. The first step of this study was to optimise digestion procedures for total chromium determination in plastic and metallic materials by inductively coupled plasma mass spectrometry (ICP-MS). High resolution (HR) ICP-MS was used to examine the influence of polyatomic interferences on the detection of the (52)Cr(+) and (53)Cr(+) isotopes. If there was strong interference with m/ z 52 for plastic materials, it was possible to use quadrupole ICP-MS for m/ z 53 if digestions were performed with HNO(3)+H(2)O(2). This mixture was also necessary for digestion of chromium from metallic materials. Extraction procedures in alkaline medium (NH(4)(+)/NH(3) buffer solution at pH 8.9) assisted by sonication were developed for determining Cr(VI) in four different corrosion-preventing coatings by HPLC-ICP-MS. After optimisation and validation with the only solid reference material certified for its Cr(VI) content (BCR 545; welding dusts), the efficiency of this extraction procedure for screw coatings was compared with that described in the EN ISO 3613 standard generally used in routine laboratories. For coatings comprising zinc and aluminium passivated in depth with chromium oxides the extraction procedure developed herein enabled determination of higher Cr(VI) concentrations. This was also observed for the screw covered with a chromium passivant layer on zinc-nickel. For coating comprising a chromium passivant layer on alkaline zinc the standardized extraction procedure was more efficient. In the case of painted metallic plate, because of a reactive matrix towards Cr(VI), its extraction without degradation was difficult to perform.","Development of analytical procedures for determination of total chromium by quadrupole ICP-MS and high-resolution ICP-MS, and hexavalent chromium by HPLC-ICP-MS, in different materials used in the automotive industry Abs: A European directive was recently adopted limiting the use of hazardous substances such as Pb, Hg, Cd, and Cr(VI) in vehicle manufacturing. From July 2003 a maximum of 2 g Cr(VI) will be authorised per vehicle in corrosion-preventing coatings of key components. As no standardised procedures are available to check if produced vehicles are in agreement with this directive, the objective of this work was to develop analytical procedures for total chromium and Cr(VI) determination in these materials. The first step of this study was to optimise digestion procedures for total chromium determination in plastic and metallic materials by inductively coupled plasma mass spectrometry (ICP-MS). High resolution (HR) ICP-MS was used to examine the influence of polyatomic interferences on the detection of the (52)Cr(+) and (53)Cr(+) isotopes. If there was strong interference with m/ z 52 for plastic materials, it was possible to use quadrupole ICP-MS for m/ z 53 if digestions were performed with HNO(3)+H(2)O(2). This mixture was also necessary for digestion of chromium from metallic materials. Extraction procedures in alkaline medium (NH(4)(+)/NH(3) buffer solution at pH 8.9) assisted by sonication were developed for determining Cr(VI) in four different corrosion-preventing coatings by HPLC-ICP-MS. After optimisation and validation with the only solid reference material certified for its Cr(VI) content (BCR 545; welding dusts), the efficiency of this extraction procedure for screw coatings was compared with that described in the EN ISO 3613 standard generally used in routine laboratories. For coatings comprising zinc and aluminium passivated in depth with chromium oxides the extraction procedure developed herein enabled determination of higher Cr(VI) concentrations. This was also observed for the screw covered with a chromium passivant layer on zinc-nickel. For coating comprising a chromium passivant layer on alkaline zinc the standardized extraction procedure was more efficient. In the case of painted metallic plate, because of a reactive matrix towards Cr(VI), its extraction without degradation was difficult to perform."
1233750,Crump et al. 2003,Dose-response and risk assessment of airborne hexavalent chromium and lung cancer mortality,"This study evaluates the dose-response relationship for inhalation exposure to hexavalent chromium [Cr(VI)] and lung cancer mortality for workers of a chromate production facility, and provides estimates of the carcinogenic potency. The data were analyzed using relative risk and additive risk dose-response models implemented with both Poisson and Cox regression. Potential confounding by birth cohort and smoking prevalence were also assessed. Lifetime cumulative exposure and highest monthly exposure were the dose metrics evaluated. The estimated lifetime additional risk of lung cancer mortality associated with 45 years of occupational exposure to 1 microg/m3 Cr(VI) (occupational exposure unit risk) was 0.00205 (90%CI: 0.00134, 0.00291) for the relative risk model and 0.00216 (90%CI: 0.00143, 0.00302) for the additive risk model assuming a linear dose response for cumulative exposure with a five-year lag. Extrapolating these findings to a continuous (e.g., environmental) exposure scenario yielded an environmental unit risk of 0.00978 (90%CI: 0.00640, 0.0138) for the relative risk model [e.g., a cancer slope factor of 34 (mg/kg-day)-1] and 0.0125 (90%CI: 0.00833, 0.0175) for the additive risk model. The relative risk model is preferred because it is more consistent with the expected trend for lung cancer risk with age. Based on statistical tests for exposure-related trend, there was no statistically significant increased lung cancer risk below lifetime cumulative occupational exposures of 1.0 mg-yr/m3, and no excess risk for workers whose highest average monthly exposure did not exceed the current Permissible Exposure Limit (52 microg/m3). It is acknowledged that this study had limited power to detect increases at these low exposure levels. These cancer potency estimates are comparable to those developed by U.S. regulatory agencies and should be useful for assessing the potential cancer hazard associated with inhaled Cr(VI).","Dose-response and risk assessment of airborne hexavalent chromium and lung cancer mortality Abs: This study evaluates the dose-response relationship for inhalation exposure to hexavalent chromium [Cr(VI)] and lung cancer mortality for workers of a chromate production facility, and provides estimates of the carcinogenic potency. The data were analyzed using relative risk and additive risk dose-response models implemented with both Poisson and Cox regression. Potential confounding by birth cohort and smoking prevalence were also assessed. Lifetime cumulative exposure and highest monthly exposure were the dose metrics evaluated. The estimated lifetime additional risk of lung cancer mortality associated with 45 years of occupational exposure to 1 microg/m3 Cr(VI) (occupational exposure unit risk) was 0.00205 (90%CI: 0.00134, 0.00291) for the relative risk model and 0.00216 (90%CI: 0.00143, 0.00302) for the additive risk model assuming a linear dose response for cumulative exposure with a five-year lag. Extrapolating these findings to a continuous (e.g., environmental) exposure scenario yielded an environmental unit risk of 0.00978 (90%CI: 0.00640, 0.0138) for the relative risk model [e.g., a cancer slope factor of 34 (mg/kg-day)-1] and 0.0125 (90%CI: 0.00833, 0.0175) for the additive risk model. The relative risk model is preferred because it is more consistent with the expected trend for lung cancer risk with age. Based on statistical tests for exposure-related trend, there was no statistically significant increased lung cancer risk below lifetime cumulative occupational exposures of 1.0 mg-yr/m3, and no excess risk for workers whose highest average monthly exposure did not exceed the current Permissible Exposure Limit (52 microg/m3). It is acknowledged that this study had limited power to detect increases at these low exposure levels. These cancer potency estimates are comparable to those developed by U.S. regulatory agencies and should be useful for assessing the potential cancer hazard associated with inhaled Cr(VI)."
1233749,Kim et al. 2003,"Oxidative stress, hogg1 expression and NF-kappaB activity in cells exposed to low level chromium","Chromium compounds are carcinogenic to the human lung, although the detailed biochemical mechanism is still unclear. To understand the carcinogenic mechanism in cells exposed to low level hexavalent chromium, we measured the generation of reactive oxygen species (ROS) and 8-hydroxydeoxyguanosine (8-OH-dG), the transcription of hogg1, which encodes an 8-OH-dG repair protein, and NF-kappaB activation levels in the A549 human lung epithelial cell line after exposure to Cr (VI) at concentrations of 12.5 to 800 microM. In A549 cells, ROS levels and DNA binding by NF-kappaB increased in proportion to the concentration of Cr (VI). These increases were diminished by pretreatment with catalase, superoxide dismutase, or D-mannitol, but the levels of 8-OH-dG and expression of hogg1 did not change significantly with Cr (VI) exposure. These results suggest that the induction of ROS and the activation of NF-kappaB are important in the carcinogenic mechanism of Cr (VI), but it is unlikely that Cr (VI) concentrations below 800 microM increase 8-OH-dG levels or the expression of hogg1.","Oxidative stress, hogg1 expression and NF-kappaB activity in cells exposed to low level chromium Abs: Chromium compounds are carcinogenic to the human lung, although the detailed biochemical mechanism is still unclear. To understand the carcinogenic mechanism in cells exposed to low level hexavalent chromium, we measured the generation of reactive oxygen species (ROS) and 8-hydroxydeoxyguanosine (8-OH-dG), the transcription of hogg1, which encodes an 8-OH-dG repair protein, and NF-kappaB activation levels in the A549 human lung epithelial cell line after exposure to Cr (VI) at concentrations of 12.5 to 800 microM. In A549 cells, ROS levels and DNA binding by NF-kappaB increased in proportion to the concentration of Cr (VI). These increases were diminished by pretreatment with catalase, superoxide dismutase, or D-mannitol, but the levels of 8-OH-dG and expression of hogg1 did not change significantly with Cr (VI) exposure. These results suggest that the induction of ROS and the activation of NF-kappaB are important in the carcinogenic mechanism of Cr (VI), but it is unlikely that Cr (VI) concentrations below 800 microM increase 8-OH-dG levels or the expression of hogg1."
1233748,Szelag et al. 2003,Assessment of efficacy of quercetin-5'-sulfonic acid sodium salt in the treatment of acute chromium poisoning: experimental studies,"Hexavalent chromium compounds exhibit higher toxicity than its trivalent compounds since chromium ions in the +6 oxidation state easily cross biological membranes. It has recently been proposed that substances reducing chromium ions from the +6 to the less toxic +3 oxidation state can be beneficial in management of acute chromium poisoning. In vitro studies also demonstrated quercetin-5 '-sulfonic acid sodium salt (NaQSA) to reduce chromium ions from the +6 to the +3 oxidation state. The aim of the study was to determine efficacy of NaQSA in treatment of acute poisoning with a hexavalent chromium compound. The experiment was carried out on male and female Wistar rats which were divided into 4 experimental (A,B,C,D) and control (K) groups. All animals received intragastrically a single CrO3 dose equal to its LD50. Thirty minutes after administration of CrO3, NaQSA was administered intragastrically at a dose of 50 mg/kg (group A) and 100 mg/kg (group B). In groups C and D, NaQSA was administered ip 2 h after administration of CrO3 and then twice a day for 4 days at doses of 50 mg/kg (group C) and 100 mg/kg (group D). Only intragastric administration of NaQSA at a dose of 100 mg/kg decreased mortality in acute poisoning with CrO3. In groups B and D, aminotransferase activity was statistically significantly dropping from day 7 of the experiment in comparison with the group K, which indicates lesser damage to the liver in animals treated with NaQSA. Bilirubin concentrations in groups B and D were also much lower than in the group K, but the difference between average bilirubin levels in these groups and the K was not statistically significant. The results of the study suggest the usefulness of NaQSA in the treatment of poisoning with hexavalent chromium compounds.","Assessment of efficacy of quercetin-5'-sulfonic acid sodium salt in the treatment of acute chromium poisoning: experimental studies Abs: Hexavalent chromium compounds exhibit higher toxicity than its trivalent compounds since chromium ions in the +6 oxidation state easily cross biological membranes. It has recently been proposed that substances reducing chromium ions from the +6 to the less toxic +3 oxidation state can be beneficial in management of acute chromium poisoning. In vitro studies also demonstrated quercetin-5 '-sulfonic acid sodium salt (NaQSA) to reduce chromium ions from the +6 to the +3 oxidation state. The aim of the study was to determine efficacy of NaQSA in treatment of acute poisoning with a hexavalent chromium compound. The experiment was carried out on male and female Wistar rats which were divided into 4 experimental (A,B,C,D) and control (K) groups. All animals received intragastrically a single CrO3 dose equal to its LD50. Thirty minutes after administration of CrO3, NaQSA was administered intragastrically at a dose of 50 mg/kg (group A) and 100 mg/kg (group B). In groups C and D, NaQSA was administered ip 2 h after administration of CrO3 and then twice a day for 4 days at doses of 50 mg/kg (group C) and 100 mg/kg (group D). Only intragastric administration of NaQSA at a dose of 100 mg/kg decreased mortality in acute poisoning with CrO3. In groups B and D, aminotransferase activity was statistically significantly dropping from day 7 of the experiment in comparison with the group K, which indicates lesser damage to the liver in animals treated with NaQSA. Bilirubin concentrations in groups B and D were also much lower than in the group K, but the difference between average bilirubin levels in these groups and the K was not statistically significant. The results of the study suggest the usefulness of NaQSA in the treatment of poisoning with hexavalent chromium compounds."
1233747,Cemeli et al. 2003,Antigenotoxic properties of selenium compounds on potassium dichromate and hydrogen peroxide,"Selenium is an environmental metal that occurs ubiquitously and is produced throughout the world for various industrial activities. Selenium has been reported to have anticarcinogenic and preventive effects in clinical and epidemiological studies. Selenium supplements can inhibit chemically-induced tumours. From the viewpoint of genotoxicity, selenium has not been adequately studied and an IARC review concluded that there were not sufficient data to consider it a carcinogen for man. In contrast, hexavalent chromium is classified as a known respiratory carcinogen producing DNA damage through free oxygen radicals. In the present study, a collaborative study has been carried out to evaluate the genotoxicity of selenium compounds and their possible interactions with potassium dichromate and hydrogen peroxide. Thus, in laboratory 1 (U.K.), the genotoxic effects of three selenium compounds were examined. Sodium selenate, sodium selenite, and selenous acid were investigated in the Ames test using strain TA102 and in the Comet assay using human lymphocytes, and also investigated for their interaction with potassium dichromate. In the Ames test, it was shown that potassium dichromate produced a highly mutagenic response, whilst the three selenium compounds did not. In combination, sodium selenate reduced the genotoxicity of potassium dichromate, but sodium selenite and selenous acid had no effect. In the Comet assay, potassium dichromate induced DNA damage, but so did the selenium compounds. In combination with potassium dichromate, however, only sodium selenate reduced its effect, whereas sodium selenite and selenous acid exacerbated DNA damage. In laboratory 2 (Spain), in the TK6 lymphoblastoid cell line, the Comet assay showed that sodium selenite was non-genotoxic, while potassium dichromate and hydrogen peroxide induced DNA damage. It was also shown that sodium selenite did not decrease the genotoxicity of potassium dichromate or hydrogen peroxide when administered as a pre-treatment or at the same time, or when potassium dichromate and sodium selenite treatments were for different time periods. Thus, only sodium selenate has shown antigenotoxic properties against potassium dichromate in the Ames test and in human lymphocytes in the Comet assay.","Antigenotoxic properties of selenium compounds on potassium dichromate and hydrogen peroxide Abs: Selenium is an environmental metal that occurs ubiquitously and is produced throughout the world for various industrial activities. Selenium has been reported to have anticarcinogenic and preventive effects in clinical and epidemiological studies. Selenium supplements can inhibit chemically-induced tumours. From the viewpoint of genotoxicity, selenium has not been adequately studied and an IARC review concluded that there were not sufficient data to consider it a carcinogen for man. In contrast, hexavalent chromium is classified as a known respiratory carcinogen producing DNA damage through free oxygen radicals. In the present study, a collaborative study has been carried out to evaluate the genotoxicity of selenium compounds and their possible interactions with potassium dichromate and hydrogen peroxide. Thus, in laboratory 1 (U.K.), the genotoxic effects of three selenium compounds were examined. Sodium selenate, sodium selenite, and selenous acid were investigated in the Ames test using strain TA102 and in the Comet assay using human lymphocytes, and also investigated for their interaction with potassium dichromate. In the Ames test, it was shown that potassium dichromate produced a highly mutagenic response, whilst the three selenium compounds did not. In combination, sodium selenate reduced the genotoxicity of potassium dichromate, but sodium selenite and selenous acid had no effect. In the Comet assay, potassium dichromate induced DNA damage, but so did the selenium compounds. In combination with potassium dichromate, however, only sodium selenate reduced its effect, whereas sodium selenite and selenous acid exacerbated DNA damage. In laboratory 2 (Spain), in the TK6 lymphoblastoid cell line, the Comet assay showed that sodium selenite was non-genotoxic, while potassium dichromate and hydrogen peroxide induced DNA damage. It was also shown that sodium selenite did not decrease the genotoxicity of potassium dichromate or hydrogen peroxide when administered as a pre-treatment or at the same time, or when potassium dichromate and sodium selenite treatments were for different time periods. Thus, only sodium selenate has shown antigenotoxic properties against potassium dichromate in the Ames test and in human lymphocytes in the Comet assay."
1233745,Fernandez-Sanchez et al. 2004,Effect of Fe0 quantity on the efficiency of integrated microbial-Fe0 treatment processes,"Batch experiments were conducted with different reaction systems to investigate how the treatment efficiency of integrated microbial-Fe0 processes is affected by the amount of Fe0 added. Abiotic experiments with hexavalent chromium and carbon tetrachloride mixtures corroborated that different pollutants could compete for reactive sites on the iron surface, which would hinder specific degradation rates when the available Fe0 surface area is relatively small (e.g., 11 m(2) l(-1)). In such cases, reductive precipitation of chromium could occlude reactive sites and significantly inhibit removal efficiency. Microbial participation in the cleanup process was also influenced by the amount of Fe0 added. Increasing the Fe0 dose (and thus the available surface area) had a stimulatory effect possibly due to a higher production of cathodic H2, which can be used as electron donor for reductive biotransformation of many pollutants. However, high Fe0 doses had an inhibitory effect due to a corrosion-induced increase in pH beyond the optimum range of the bacteria. This suggest that there may be a system-specific, optimum quantity of Fe0 that satisfies availability requirements to preclude contaminant competition for reactive sites and biological requirements for H2 production while minimizing inhibitory increases in pH. Results also confirmed extensive RDX mineralization in bioaugmented (but not in abiotic) Fe0 systems, and support the notion that permeable reactive iron barriers performance might be enhanced by the participation of some microorganisms.","Effect of Fe0 quantity on the efficiency of integrated microbial-Fe0 treatment processes Abs: Batch experiments were conducted with different reaction systems to investigate how the treatment efficiency of integrated microbial-Fe0 processes is affected by the amount of Fe0 added. Abiotic experiments with hexavalent chromium and carbon tetrachloride mixtures corroborated that different pollutants could compete for reactive sites on the iron surface, which would hinder specific degradation rates when the available Fe0 surface area is relatively small (e.g., 11 m(2) l(-1)). In such cases, reductive precipitation of chromium could occlude reactive sites and significantly inhibit removal efficiency. Microbial participation in the cleanup process was also influenced by the amount of Fe0 added. Increasing the Fe0 dose (and thus the available surface area) had a stimulatory effect possibly due to a higher production of cathodic H2, which can be used as electron donor for reductive biotransformation of many pollutants. However, high Fe0 doses had an inhibitory effect due to a corrosion-induced increase in pH beyond the optimum range of the bacteria. This suggest that there may be a system-specific, optimum quantity of Fe0 that satisfies availability requirements to preclude contaminant competition for reactive sites and biological requirements for H2 production while minimizing inhibitory increases in pH. Results also confirmed extensive RDX mineralization in bioaugmented (but not in abiotic) Fe0 systems, and support the notion that permeable reactive iron barriers performance might be enhanced by the participation of some microorganisms."
1233744,Chapman et al. 2004,Construction of a subtractive library from hexavalent chromium treated winter flounder (Pseudopleuronectes americanus) reveals alterations in non-selenium glutathione peroxidases,"Chromium is released during several industrial processes and has accumulated in some estuarine areas. Its effects on mammals have been widely studied, but relatively little information is available on its effects on fish. Gene expression changes are useful biomarkers that can provide information about toxicant exposure and effects, as well as the health of an organism and its ability to adapt to its surroundings. Therefore, we investigated the effects of Cr(VI) on gene expression in the sediment dwelling fish, winter flounder (Pseudopleuronectes americanus). Winter flounder ranging from 300 to 360 g were injected i.p. with Cr(VI) as chromium oxide at 25 microg/kg chromium in 0.15N KCl. Twenty-four hours following injections, winter flounder were euthanized with MS-222 and the livers were excised. Half of the livers were used to make cytosol and the other half were used to isolate mRNA for subtractive hybridization. Subtractive clones obtained were spotted onto nylon filters, which revealed several genes with potentially altered expression due to Cr(VI), including an alpha class GST, 1-Cys peroxiredoxin (a non-selenium glutathione peroxidase), a P-450 2X subfamily member, two elongation factors (EF-1 gamma and EF-2), and complement component C3. Semi-quantitative RT-PCR was performed and confirmed that Cr(VI) down-regulated complement component C3, an EST, and two potential glutathione peroxidases, GSTA3 and 1-Cys peroxiredoxin. In addition, cytosolic GSH peroxidase activity was reduced, and silver stained SDS-PAGE gels from glutathione-affinity purified cytosol demonstrated that a 27.1 kDa GSH-binding protein was down-regulated greater than 50%. Taken together, Cr(VI) significantly altered the expression of several genes including two potential glutathione peroxidases in winter flounder.","Construction of a subtractive library from hexavalent chromium treated winter flounder (Pseudopleuronectes americanus) reveals alterations in non-selenium glutathione peroxidases Abs: Chromium is released during several industrial processes and has accumulated in some estuarine areas. Its effects on mammals have been widely studied, but relatively little information is available on its effects on fish. Gene expression changes are useful biomarkers that can provide information about toxicant exposure and effects, as well as the health of an organism and its ability to adapt to its surroundings. Therefore, we investigated the effects of Cr(VI) on gene expression in the sediment dwelling fish, winter flounder (Pseudopleuronectes americanus). Winter flounder ranging from 300 to 360 g were injected i.p. with Cr(VI) as chromium oxide at 25 microg/kg chromium in 0.15N KCl. Twenty-four hours following injections, winter flounder were euthanized with MS-222 and the livers were excised. Half of the livers were used to make cytosol and the other half were used to isolate mRNA for subtractive hybridization. Subtractive clones obtained were spotted onto nylon filters, which revealed several genes with potentially altered expression due to Cr(VI), including an alpha class GST, 1-Cys peroxiredoxin (a non-selenium glutathione peroxidase), a P-450 2X subfamily member, two elongation factors (EF-1 gamma and EF-2), and complement component C3. Semi-quantitative RT-PCR was performed and confirmed that Cr(VI) down-regulated complement component C3, an EST, and two potential glutathione peroxidases, GSTA3 and 1-Cys peroxiredoxin. In addition, cytosolic GSH peroxidase activity was reduced, and silver stained SDS-PAGE gels from glutathione-affinity purified cytosol demonstrated that a 27.1 kDa GSH-binding protein was down-regulated greater than 50%. Taken together, Cr(VI) significantly altered the expression of several genes including two potential glutathione peroxidases in winter flounder."
1233743,Mäkinen and  Linnainmaa 2004,Dermal exposure to chromium in electroplating,"<strong>OBJECTIVES: </strong>The aim of the study was to measure the dermal and respiratory exposure levels of hexavalent chromium during electroplating work.<br /><br /><strong>METHODS: </strong>Potential dermal exposure of the body was measured with patch samples and actual exposure of hands with hand-wash samples. For comparison, personal air samples were also collected.<br /><br /><strong>RESULTS: </strong>The exposure varied widely between workers. The range of body and hand exposure to the electroplating solution was 0.17-28.1 mg/h and 0.04-6.37 mg/h, respectively. Hands and lower limbs were the most contaminated body parts.<br /><br /><strong>CONCLUSIONS: </strong>The results of breathing zone samples and dermal exposure did not correlate with each other. In manual electroplating processes, dermal exposure was higher than in semi-automatic and automatic processes. The amount of hexavalent chromium the workers were exposed to is probably high enough to cause a risk of skin sensitization.","Dermal exposure to chromium in electroplating Abs: <strong>OBJECTIVES: </strong>The aim of the study was to measure the dermal and respiratory exposure levels of hexavalent chromium during electroplating work.<br /><br /><strong>METHODS: </strong>Potential dermal exposure of the body was measured with patch samples and actual exposure of hands with hand-wash samples. For comparison, personal air samples were also collected.<br /><br /><strong>RESULTS: </strong>The exposure varied widely between workers. The range of body and hand exposure to the electroplating solution was 0.17-28.1 mg/h and 0.04-6.37 mg/h, respectively. Hands and lower limbs were the most contaminated body parts.<br /><br /><strong>CONCLUSIONS: </strong>The results of breathing zone samples and dermal exposure did not correlate with each other. In manual electroplating processes, dermal exposure was higher than in semi-automatic and automatic processes. The amount of hexavalent chromium the workers were exposed to is probably high enough to cause a risk of skin sensitization."
1233742,Isakov et al. 2004,Near-field dispersion modeling for regulatory applications,"This paper evaluates the application of dispersion models to estimate near-field pollutant concentrations in two case studies. The Industrial Source Complex Short-Term Model (ISCST3) was evaluated with hexavalent chromium measurements collected within 100 m of two facilities in Barrio Logan, San Diego, CA. ISCST3 provided reasonable estimates for higher pollutant concentrations but underestimated lower concentrations. To understand the observed distribution of concentrations in Barrio Logan, a recently conducted tracer experiment was analyzed. The tracer, sulfur hexafluoride, was released at ambient temperature from an urban facility at the University of California at Riverside, and concentrations were measured within 20 m of the source. Modeling results indicated that Industrial Source Complex-Plume Rise Model Enhancement and American Meteorological Society/U.S. Environmental Protection Agency Regulatory Model-Plume Rise Model Enhancement overestimated high concentrations and underestimated low concentrations. A diagnostic study with a simple Gaussian dispersion model that incorporated site-specific meteorology was used to evaluate model results. This study found that incorporating lateral meandering for nonbuoyant urban plumes in Gaussian dispersion models could improve concentration estimates even when downwash is not considered. Incorporating a meandering component in ISCST3 resulted in improvements in estimating hexavalent chromium concentrations in Barrio Logan. Credible near-source concentration estimates depend on accurate characterization of emissions, onsite micrometeorology, and a method to account for lateral meandering in the near field.","Near-field dispersion modeling for regulatory applications Abs: This paper evaluates the application of dispersion models to estimate near-field pollutant concentrations in two case studies. The Industrial Source Complex Short-Term Model (ISCST3) was evaluated with hexavalent chromium measurements collected within 100 m of two facilities in Barrio Logan, San Diego, CA. ISCST3 provided reasonable estimates for higher pollutant concentrations but underestimated lower concentrations. To understand the observed distribution of concentrations in Barrio Logan, a recently conducted tracer experiment was analyzed. The tracer, sulfur hexafluoride, was released at ambient temperature from an urban facility at the University of California at Riverside, and concentrations were measured within 20 m of the source. Modeling results indicated that Industrial Source Complex-Plume Rise Model Enhancement and American Meteorological Society/U.S. Environmental Protection Agency Regulatory Model-Plume Rise Model Enhancement overestimated high concentrations and underestimated low concentrations. A diagnostic study with a simple Gaussian dispersion model that incorporated site-specific meteorology was used to evaluate model results. This study found that incorporating lateral meandering for nonbuoyant urban plumes in Gaussian dispersion models could improve concentration estimates even when downwash is not considered. Incorporating a meandering component in ISCST3 resulted in improvements in estimating hexavalent chromium concentrations in Barrio Logan. Credible near-source concentration estimates depend on accurate characterization of emissions, onsite micrometeorology, and a method to account for lateral meandering in the near field."
1233740,Torricelli et al. 2004,"Cadmium tolerance, cysteine and thiol peptide levels in wild type and chromium-tolerant strains of Scenedesmus acutus (Chlorophyceae)","Two strains of the unicellular green alga Scenedesmus acutus with different sensitivity to hexavalent chromium were compared for their tolerance of cadmium, by means of growth and recovery tests, and determination of cysteine, reduced glutathione and phytochelatin content, after short-term exposure to various cadmium concentrations (from 1.125 to 27 microM). Growth experiments showed that, after 7-day treatments with cadmium, the chromium-tolerant strain reached a significantly higher cell density and, after 24-h exposure to Cd, was able to resume growth significantly better than the wild type. Constitutive level of cysteine was higher in the chromium-tolerant strain, while glutathione levels were similar in the two strains. The higher content of cysteine and the maintenance of both reduced glutathione and phytochelatin high levels in the presence of cadmium, support the higher cadmium co-tolerance of the chromium-tolerant strain in comparison with the wild type one.","Cadmium tolerance, cysteine and thiol peptide levels in wild type and chromium-tolerant strains of Scenedesmus acutus (Chlorophyceae) Abs: Two strains of the unicellular green alga Scenedesmus acutus with different sensitivity to hexavalent chromium were compared for their tolerance of cadmium, by means of growth and recovery tests, and determination of cysteine, reduced glutathione and phytochelatin content, after short-term exposure to various cadmium concentrations (from 1.125 to 27 microM). Growth experiments showed that, after 7-day treatments with cadmium, the chromium-tolerant strain reached a significantly higher cell density and, after 24-h exposure to Cd, was able to resume growth significantly better than the wild type. Constitutive level of cysteine was higher in the chromium-tolerant strain, while glutathione levels were similar in the two strains. The higher content of cysteine and the maintenance of both reduced glutathione and phytochelatin high levels in the presence of cadmium, support the higher cadmium co-tolerance of the chromium-tolerant strain in comparison with the wild type one."
1233739,Brown et al. 2004,Lung cancer and internal lung doses among plutonium workers at the Rocky Flats Plant: a case-control study,"The authors conducted a nested case-control study of the association between lung cancer mortality and cumulative internal lung doses among a cohort of workers employed at the Rocky Flats Plant in Colorado from 1951 to 1989. Cases (n = 180) were individually matched with controls (n = 720) on age, sex, and birth year. Annual doses to the lung from plutonium, americium, and uranium isotopes were calculated for each worker with an internal dosimetry model. Lung cancer risk was elevated among workers with cumulative internal lung doses of more than 400 mSv in several different analytical models. The dose-response relation was not consistent at high doses. Restricting analysis to those employed for 15-25 years produced a statistically significant linear trend with dose (chi-square = 67.2, p &lt; 0.001), suggesting a strong healthy worker survivor effect. The association between age at first internal lung dose and lung cancer mortality was statistically significant (odds ratio = 1.05, 95% confidence interval: 1.01, 1.10). No associations were found between lung cancer mortality and cumulative external penetrating radiation dose or cumulative exposures to asbestos, beryllium, hexavalent chromium, or nickel.","Lung cancer and internal lung doses among plutonium workers at the Rocky Flats Plant: a case-control study Abs: The authors conducted a nested case-control study of the association between lung cancer mortality and cumulative internal lung doses among a cohort of workers employed at the Rocky Flats Plant in Colorado from 1951 to 1989. Cases (n = 180) were individually matched with controls (n = 720) on age, sex, and birth year. Annual doses to the lung from plutonium, americium, and uranium isotopes were calculated for each worker with an internal dosimetry model. Lung cancer risk was elevated among workers with cumulative internal lung doses of more than 400 mSv in several different analytical models. The dose-response relation was not consistent at high doses. Restricting analysis to those employed for 15-25 years produced a statistically significant linear trend with dose (chi-square = 67.2, p &lt; 0.001), suggesting a strong healthy worker survivor effect. The association between age at first internal lung dose and lung cancer mortality was statistically significant (odds ratio = 1.05, 95% confidence interval: 1.01, 1.10). No associations were found between lung cancer mortality and cumulative external penetrating radiation dose or cumulative exposures to asbestos, beryllium, hexavalent chromium, or nickel."
1233737,Lee et al. 2004,Modified comet assay as a biomarker of sodium dichromate-induced oxidative DNA damage: Optimization and reproducibility,"Hexavalent chromium (Cr[VI]) is a genotoxic carcinogen that has been associated with an increased risk of nasal and respiratory tract cancers following occupational exposure. Although the precise mechanism(s) remain to be elucidated, there is evidence for a role of oxidative DNA damage in the genotoxicity of Cr(VI). In the current study, human white blood cells were treated in vitro with non-cytotoxic concentrations of sodium dichromate (1-100 microM) for 1 h. Analysis by immunocytochemistry indicated the presence of elevated levels of 8-oxo-7,8-dihydro-2'-deoxyguanosine at concentrations of sodium dichromate greater than 10 microM. In contrast, the lowest concentration of dichromate that resulted in a statistically significant increase in levels of formamidopyrimidine DNA glycosylase (FPG)-dependent DNA strand breaks was 100 nM (p<0.05). In addition, levels of both control and dichromate-induced FPG-dependent strand breaks from blood samples taken from the same individuals over 10 months proved remarkably reproducible in the individuals studied. The coefficients of variation over three different times of the year in control and dichromate-induced oxidative DNA damage for the four individuals were 54, 1, 37 and 4, and 45, 6, 21 and 18%, respectively. In summary, these results indicate that physiologically relevant, nanomolar concentrations of sodium dichromate cause DNA base oxidation in human white blood cells in vitro as assessed by the FPG-modified comet assay. Furthermore, comet assay data from an individual are reproducible over an extended period. This consistency is sufficient to suggest that the modified comet assay might prove to be a useful and sensitive biomonitoring tool for individuals occupationally exposed to hexavalent chromium.","Modified comet assay as a biomarker of sodium dichromate-induced oxidative DNA damage: Optimization and reproducibility Abs: Hexavalent chromium (Cr[VI]) is a genotoxic carcinogen that has been associated with an increased risk of nasal and respiratory tract cancers following occupational exposure. Although the precise mechanism(s) remain to be elucidated, there is evidence for a role of oxidative DNA damage in the genotoxicity of Cr(VI). In the current study, human white blood cells were treated in vitro with non-cytotoxic concentrations of sodium dichromate (1-100 microM) for 1 h. Analysis by immunocytochemistry indicated the presence of elevated levels of 8-oxo-7,8-dihydro-2'-deoxyguanosine at concentrations of sodium dichromate greater than 10 microM. In contrast, the lowest concentration of dichromate that resulted in a statistically significant increase in levels of formamidopyrimidine DNA glycosylase (FPG)-dependent DNA strand breaks was 100 nM (p<0.05). In addition, levels of both control and dichromate-induced FPG-dependent strand breaks from blood samples taken from the same individuals over 10 months proved remarkably reproducible in the individuals studied. The coefficients of variation over three different times of the year in control and dichromate-induced oxidative DNA damage for the four individuals were 54, 1, 37 and 4, and 45, 6, 21 and 18%, respectively. In summary, these results indicate that physiologically relevant, nanomolar concentrations of sodium dichromate cause DNA base oxidation in human white blood cells in vitro as assessed by the FPG-modified comet assay. Furthermore, comet assay data from an individual are reproducible over an extended period. This consistency is sufficient to suggest that the modified comet assay might prove to be a useful and sensitive biomonitoring tool for individuals occupationally exposed to hexavalent chromium."
1233736,Erdem et al. 2004,Cr(VI) reduction in aqueous solutions by siderite,"Hexavalent chromium is a common and toxic pollutant in soils and wastewaters. Reduction of the mobile Cr(VI) to less mobile and less toxic Cr(III) is a solution for decontamination of industrial effluents. In this study, the reduction of hexavalent chromium in aqueous solutions by siderite was investigated. The influences of amount of acid, contact time, siderite dosage, initial Cr(VI) concentration, temperature and particle size of siderite have been tested in batch runs. The process was found to be acid, temperature and concentration dependent. The amount of acid is the most effective parameter affecting the Cr(VI) reduction since carbonaceous gangue minerals consume acid by side reactions. The highest Cr(VI) reduction efficiency (100%) occurred in the 50 mg/l Cr(VI) solution containing two times acid with respect to stoichiometric amount of Cr(VI) and at the conditions of siderite dosage 20 g/l, contact time 120 min and temperature 25 degrees C. Reduction efficiency increased with increase in temperature and decrease in particle size. The reduction capacity of siderite was found to be 17 mg-Cr(VI)/g.","Cr(VI) reduction in aqueous solutions by siderite Abs: Hexavalent chromium is a common and toxic pollutant in soils and wastewaters. Reduction of the mobile Cr(VI) to less mobile and less toxic Cr(III) is a solution for decontamination of industrial effluents. In this study, the reduction of hexavalent chromium in aqueous solutions by siderite was investigated. The influences of amount of acid, contact time, siderite dosage, initial Cr(VI) concentration, temperature and particle size of siderite have been tested in batch runs. The process was found to be acid, temperature and concentration dependent. The amount of acid is the most effective parameter affecting the Cr(VI) reduction since carbonaceous gangue minerals consume acid by side reactions. The highest Cr(VI) reduction efficiency (100%) occurred in the 50 mg/l Cr(VI) solution containing two times acid with respect to stoichiometric amount of Cr(VI) and at the conditions of siderite dosage 20 g/l, contact time 120 min and temperature 25 degrees C. Reduction efficiency increased with increase in temperature and decrease in particle size. The reduction capacity of siderite was found to be 17 mg-Cr(VI)/g."
1233735,Wakeman et al. 2004,The ATM-SMC1 pathway is essential for activation of the chromium[VI]-induced S-phase checkpoint,"Hexavalent chromium (Cr[VI]) is a common industrial waste product, an environmental pollutant, and a recognized human carcinogen. Following cellular uptake, Cr[VI] can cause DNA damage, however, the mechanisms by which mammalian cells respond to Cr-induced DNA damage remain to be elucidated. Using single cell gel electrophoresis (e.g., Comet Assay) and immunofluoresence microscopy to detect the presence of gamma-H2AX foci, we find that Cr[VI] induces DNA double-strand breaks similar to ionizing radiation (IR). We also demonstrated that ataxia telangiectasia mutated (ATM) is activated in response to Cr[VI] and exposure to Cr[VI] triggers a dose and ATM-dependent S-phase arrest. Further, we document that ATM is required for phosphorylation of the structural maintenance of chromosome protein 1 (SMC1). Finally, we find that ATM-dependent phosphorylation of SMC1 is required to facilitate S-phase cell-cycle arrest in response to Cr[VI] exposure. Collectively, these results indicate that the ATM-SMC1 pathway plays a critical role in cellular response to Cr[VI].","The ATM-SMC1 pathway is essential for activation of the chromium[VI]-induced S-phase checkpoint Abs: Hexavalent chromium (Cr[VI]) is a common industrial waste product, an environmental pollutant, and a recognized human carcinogen. Following cellular uptake, Cr[VI] can cause DNA damage, however, the mechanisms by which mammalian cells respond to Cr-induced DNA damage remain to be elucidated. Using single cell gel electrophoresis (e.g., Comet Assay) and immunofluoresence microscopy to detect the presence of gamma-H2AX foci, we find that Cr[VI] induces DNA double-strand breaks similar to ionizing radiation (IR). We also demonstrated that ataxia telangiectasia mutated (ATM) is activated in response to Cr[VI] and exposure to Cr[VI] triggers a dose and ATM-dependent S-phase arrest. Further, we document that ATM is required for phosphorylation of the structural maintenance of chromosome protein 1 (SMC1). Finally, we find that ATM-dependent phosphorylation of SMC1 is required to facilitate S-phase cell-cycle arrest in response to Cr[VI] exposure. Collectively, these results indicate that the ATM-SMC1 pathway plays a critical role in cellular response to Cr[VI]."
1233734,Peña-Castro et al. 2004,Phenotypic plasticity in Scenedesmus incrassatulus (Chlorophyceae) in response to heavy metals stress,"The microalgae genus Scenedesmus is commonly found in freshwater bodies, wastewater facilities and water polluted with heavy metals. Phenotypic plasticity in Scenedesmus has been documented in response to a wide variety of conditions; however, heavy metals have not been comprehensively documented as phenotypic plasticity inducers. In this study, we report the phenotypic plasticity of Scenedesmus incrassatulus (a non-spiny, four-cell coenobium forming species) in response to EC(50) value of copper, cadmium and hexavalent chromium. S. incrassatulus was grown in batch cultures in the presence of each metal. Chlorophyll-a content, cell size, parameters derived from the schematic energy-flux model for photosystem II, and morphotype expressions were recorded. Divalent cation metals induced unicellular forms, and hexavalent chromium produced out-of-shape coenobia corresponding to various stages of autospore formation. The changes induced by divalent metals were interpreted as phenotypic plasticity, because they were always associated to population doublings and were reversible when toxicant pressure was removed (only for Cu). Copper was the best inductor of unicellular forms and also affected significantly all the photosynthetic parameters measured. The developed morphotypes could confer ecological advantages to S. incrassatulus in metal stressed environments.","Phenotypic plasticity in Scenedesmus incrassatulus (Chlorophyceae) in response to heavy metals stress Abs: The microalgae genus Scenedesmus is commonly found in freshwater bodies, wastewater facilities and water polluted with heavy metals. Phenotypic plasticity in Scenedesmus has been documented in response to a wide variety of conditions; however, heavy metals have not been comprehensively documented as phenotypic plasticity inducers. In this study, we report the phenotypic plasticity of Scenedesmus incrassatulus (a non-spiny, four-cell coenobium forming species) in response to EC(50) value of copper, cadmium and hexavalent chromium. S. incrassatulus was grown in batch cultures in the presence of each metal. Chlorophyll-a content, cell size, parameters derived from the schematic energy-flux model for photosystem II, and morphotype expressions were recorded. Divalent cation metals induced unicellular forms, and hexavalent chromium produced out-of-shape coenobia corresponding to various stages of autospore formation. The changes induced by divalent metals were interpreted as phenotypic plasticity, because they were always associated to population doublings and were reversible when toxicant pressure was removed (only for Cu). Copper was the best inductor of unicellular forms and also affected significantly all the photosynthetic parameters measured. The developed morphotypes could confer ecological advantages to S. incrassatulus in metal stressed environments."
1233733,Ha et al. 2004,Generation of S phase-dependent DNA double-strand breaks by Cr(VI) exposure: involvement of ATM in Cr(VI) induction of gamma-H2AX,"Certain hexavalent chromium [Cr(VI)] compounds are implicated as occupational respiratory carcinogens. Cr(VI) induces a broad spectrum of DNA damage, but Cr(VI)-induced DNA double-strand breaks (DSBs) have not been reported. Previously we found that Cr(VI) activates the ataxia telangiectasia mutated (ATM) kinase. ATM is activated specifically in response to DSBs. Therefore, the objective of this study was to investigate DSB induction by Cr(VI) exposure with the overarching hypothesis that S phase-dependent DSBs are produced by Cr(VI) exposure. To test this hypothesis, normal human fibroblasts were treated with either Cr(VI) or neocarzinostatin (NCS). DSBs were analyzed by both comet assay under neutral conditions, which detects primarily DNA DSBs, and phosphorylation of histone H2AX (gamma-H2AX) and the resultant formation of nuclear foci, which are considered to be indicative of DSBs. Induction of DSBs was observed after Cr(VI) exposure, however, the Cr(VI)-induced DSBs were abrogated by G(1) synchronization. Furthermore, our data showed that Cr(VI)-induced DSBs were only observed in the S phase population, whereas no significant DSBs were observed in Cr(VI)-treated G(1) synchronized cells. In contrast, NCS-induced DSBs were equally distributed in all cell cycle phases in both asynchronous and G(1) synchronized cells. Moreover, Cr(VI)-induced gamma-H2AX foci formation was restricted to PCNA-positive cells, whereas NCS-induced gamma-H2AX foci formed in both PCNA-positive and PCNA-negative cells. These results indicate that Cr(VI)-induced DSBs are S phase-dependent. Finally, our data showed that Cr(VI)-induced gamma-H2AX production was significantly decreased in ATM(-/-) cells compared with ATM(+/+) cells. Taken together, these results suggest that Cr(VI)-induced activation of ATM involves the formation of S phase-dependent DSBs. Examining the mechanism of Cr(VI)-induced DSBs will aid in understanding the interrelated mechanisms of Cr(VI) toxicity and carcinogenesis.","Generation of S phase-dependent DNA double-strand breaks by Cr(VI) exposure: involvement of ATM in Cr(VI) induction of gamma-H2AX Abs: Certain hexavalent chromium [Cr(VI)] compounds are implicated as occupational respiratory carcinogens. Cr(VI) induces a broad spectrum of DNA damage, but Cr(VI)-induced DNA double-strand breaks (DSBs) have not been reported. Previously we found that Cr(VI) activates the ataxia telangiectasia mutated (ATM) kinase. ATM is activated specifically in response to DSBs. Therefore, the objective of this study was to investigate DSB induction by Cr(VI) exposure with the overarching hypothesis that S phase-dependent DSBs are produced by Cr(VI) exposure. To test this hypothesis, normal human fibroblasts were treated with either Cr(VI) or neocarzinostatin (NCS). DSBs were analyzed by both comet assay under neutral conditions, which detects primarily DNA DSBs, and phosphorylation of histone H2AX (gamma-H2AX) and the resultant formation of nuclear foci, which are considered to be indicative of DSBs. Induction of DSBs was observed after Cr(VI) exposure, however, the Cr(VI)-induced DSBs were abrogated by G(1) synchronization. Furthermore, our data showed that Cr(VI)-induced DSBs were only observed in the S phase population, whereas no significant DSBs were observed in Cr(VI)-treated G(1) synchronized cells. In contrast, NCS-induced DSBs were equally distributed in all cell cycle phases in both asynchronous and G(1) synchronized cells. Moreover, Cr(VI)-induced gamma-H2AX foci formation was restricted to PCNA-positive cells, whereas NCS-induced gamma-H2AX foci formed in both PCNA-positive and PCNA-negative cells. These results indicate that Cr(VI)-induced DSBs are S phase-dependent. Finally, our data showed that Cr(VI)-induced gamma-H2AX production was significantly decreased in ATM(-/-) cells compared with ATM(+/+) cells. Taken together, these results suggest that Cr(VI)-induced activation of ATM involves the formation of S phase-dependent DSBs. Examining the mechanism of Cr(VI)-induced DSBs will aid in understanding the interrelated mechanisms of Cr(VI) toxicity and carcinogenesis."
1233732,Park et al. 2004,Hexavalent chromium and lung cancer in the chromate industry: a quantitative risk assessment,"The purpose of this investigation was to estimate excess lifetime risk of lung cancer death resulting from occupational exposure to hexavalent-chromium-containing dusts and mists. The mortality experience in a previously studied cohort of 2,357 chromate chemical production workers with 122 lung cancer deaths was analyzed with Poisson regression methods. Extensive records of air samples evaluated for water-soluble total hexavalent chromium were available for the entire employment history of this cohort. Six different models of exposure-response for hexavalent chromium were evaluated by comparing deviances and inspection of cubic splines. Smoking (pack-years) imputed from cigarette use at hire was included in the model. Lifetime risks of lung cancer death from exposure to hexavalent chromium (assuming up to 45 years of exposure) were estimated using an actuarial calculation that accounts for competing causes of death. A linear relative rate model gave a good and readily interpretable fit to the data. The estimated rate ratio for 1 mg/m3-yr of cumulative exposure to hexavalent chromium (as CrO3), with a lag of five years, was RR=2.44 (95% CI=1.54-3.83). The excess lifetime risk of lung cancer death from exposure to hexavalent chromium at the current OSHA permissible exposure limit (PEL) (0.10 mg/m3) was estimated to be 255 per 1,000 (95% CI: 109-416). This estimate is comparable to previous estimates by U.S. EPA, California EPA, and OSHA using different occupational data. Our analysis predicts that current occupational standards for hexavalent chromium permit a lifetime excess risk of dying of lung cancer that exceeds 1 in 10, which is consistent with previous risk assessments.","Hexavalent chromium and lung cancer in the chromate industry: a quantitative risk assessment Abs: The purpose of this investigation was to estimate excess lifetime risk of lung cancer death resulting from occupational exposure to hexavalent-chromium-containing dusts and mists. The mortality experience in a previously studied cohort of 2,357 chromate chemical production workers with 122 lung cancer deaths was analyzed with Poisson regression methods. Extensive records of air samples evaluated for water-soluble total hexavalent chromium were available for the entire employment history of this cohort. Six different models of exposure-response for hexavalent chromium were evaluated by comparing deviances and inspection of cubic splines. Smoking (pack-years) imputed from cigarette use at hire was included in the model. Lifetime risks of lung cancer death from exposure to hexavalent chromium (assuming up to 45 years of exposure) were estimated using an actuarial calculation that accounts for competing causes of death. A linear relative rate model gave a good and readily interpretable fit to the data. The estimated rate ratio for 1 mg/m3-yr of cumulative exposure to hexavalent chromium (as CrO3), with a lag of five years, was RR=2.44 (95% CI=1.54-3.83). The excess lifetime risk of lung cancer death from exposure to hexavalent chromium at the current OSHA permissible exposure limit (PEL) (0.10 mg/m3) was estimated to be 255 per 1,000 (95% CI: 109-416). This estimate is comparable to previous estimates by U.S. EPA, California EPA, and OSHA using different occupational data. Our analysis predicts that current occupational standards for hexavalent chromium permit a lifetime excess risk of dying of lung cancer that exceeds 1 in 10, which is consistent with previous risk assessments."
1233731,Steinhagen et al. 2004,Effect of hexavalent carcinogenic chromium on carp Cyprinus carpio immune cells,"Chromium is widely used in industrial processes, and is released into aquatic environments by electroplating, tannery and textile industries. Fishes in natural waters or in aquaculture facilities supplied with these waters are exposed to chromium waste and are presumed to be affected by deposits. Herein, we examine the effect of hexavalent chromium on carp Cyprinus carpio derived immune cells. In vitro exposure of carp leukocytes to hexavalent chromium induced cytotoxicity, decreased mitogen-induced lymphocyte activation and phagocyte functions at concentrations between 2 and 200 micromol Cr l(-1). Neutrophils responded to chromium challenge by changes in cell shape together with reduced nitric oxide and reactive oxygen production. This occurred at much lower concentrations than for the cytotoxic effects seen in leukocyte cultures derived from peripheral blood or pronephros. In a similar way, activation of carp lymphocytes by pokeweed mitogen was reduced in a dose-dependent manner, while cytotoxic effects on non-activated lymphocytes were observed at much higher doses of 200 micromol Cr l(-1). Altered lymphocyte and neutrophil functions are considered to be responsible for decreased resistance to pathogens observed in fishes under chronic chromium challenge.","Effect of hexavalent carcinogenic chromium on carp Cyprinus carpio immune cells Abs: Chromium is widely used in industrial processes, and is released into aquatic environments by electroplating, tannery and textile industries. Fishes in natural waters or in aquaculture facilities supplied with these waters are exposed to chromium waste and are presumed to be affected by deposits. Herein, we examine the effect of hexavalent chromium on carp Cyprinus carpio derived immune cells. In vitro exposure of carp leukocytes to hexavalent chromium induced cytotoxicity, decreased mitogen-induced lymphocyte activation and phagocyte functions at concentrations between 2 and 200 micromol Cr l(-1). Neutrophils responded to chromium challenge by changes in cell shape together with reduced nitric oxide and reactive oxygen production. This occurred at much lower concentrations than for the cytotoxic effects seen in leukocyte cultures derived from peripheral blood or pronephros. In a similar way, activation of carp lymphocytes by pokeweed mitogen was reduced in a dose-dependent manner, while cytotoxic effects on non-activated lymphocytes were observed at much higher doses of 200 micromol Cr l(-1). Altered lymphocyte and neutrophil functions are considered to be responsible for decreased resistance to pathogens observed in fishes under chronic chromium challenge."
1233730,van Wijngaarden et al. 2004,Evaluation of the exposure-response relationship of lung cancer mortality and occupational exposure to hexavalent chromium based on published epidemiological data,"Some have suggested a threshold mechanism for the carcinogenicity of exposure to hexavalent chromium, Cr(VI). We evaluated the nature of the exposure-response relationship between occupational exposure to Cr(VI) and respiratory cancer based on results of two recently published epidemiological cohort studies. The combined cohort comprised a total of 2,849 workers employed at two U.S. chromate production plants between 1940 and 1974. Standardized mortality ratios (SMRs) for lung cancer in relation to cumulative Cr(VI) exposure categories were reported using regional mortality rates. Linear additive and multiplicative relative risk regression models were fit to the SMRs of the individual and combined studies. Both models fit the data from the individual studies reasonably well; however, the fit was somewhat less adequate for the pooled data. Meta-analysis of the slope estimates obtained from the multiplicative relative risk model showed substantial heterogeneity between the two epidemiological studies. In conclusion, these data indicate that a linear dose response describes the relationship between Cr(VI) and lung cancer reasonably well, and therefore these analyses do not necessarily support the threshold hypothesis for the lung carcinogenicity of Cr(VI). However, these results must be interpreted with recognition of the limitations of the use of epidemiological data in the evaluation of nonlinear exposure-response patterns.","Evaluation of the exposure-response relationship of lung cancer mortality and occupational exposure to hexavalent chromium based on published epidemiological data Abs: Some have suggested a threshold mechanism for the carcinogenicity of exposure to hexavalent chromium, Cr(VI). We evaluated the nature of the exposure-response relationship between occupational exposure to Cr(VI) and respiratory cancer based on results of two recently published epidemiological cohort studies. The combined cohort comprised a total of 2,849 workers employed at two U.S. chromate production plants between 1940 and 1974. Standardized mortality ratios (SMRs) for lung cancer in relation to cumulative Cr(VI) exposure categories were reported using regional mortality rates. Linear additive and multiplicative relative risk regression models were fit to the SMRs of the individual and combined studies. Both models fit the data from the individual studies reasonably well; however, the fit was somewhat less adequate for the pooled data. Meta-analysis of the slope estimates obtained from the multiplicative relative risk model showed substantial heterogeneity between the two epidemiological studies. In conclusion, these data indicate that a linear dose response describes the relationship between Cr(VI) and lung cancer reasonably well, and therefore these analyses do not necessarily support the threshold hypothesis for the lung carcinogenicity of Cr(VI). However, these results must be interpreted with recognition of the limitations of the use of epidemiological data in the evaluation of nonlinear exposure-response patterns."
1233729,Sabty-Daily et al. 2005,Size distribution of chromate paint aerosol generated in a bench-scale spray booth,"Spray painters are potentially exposed to aerosols containing hexavalent chromium [Cr(VI)] via inhalation of chromate-based paint sprays. Evaluating the particle size distribution of a paint spray aerosol, and the variables that may affect this distribution, is necessary to determine the site and degree of respiratory deposition and the damage that may result from inhaled Cr(VI)-containing paint particles. This study examined the effect of spray gun atomization pressure, aerosol generation source and aerosol aging on the size distribution of chromate-based paint overspray aerosols generated in a bench-scale paint spray booth. The study also determined the effect of particle bounce inside a Marple personal cascade impactor on measured size distributions of paint spray aerosols. Marple personal cascade impactors with a modified inlet were used for sample collection. The data indicated that paint particle bounce did not occur inside the cascade impactors sufficiently to affect size distribution when using uncoated stainless steel or PVC substrate sampling media. A decrease in paint aerosol mass median aerodynamic diameter (MMAD) from 8.2 to 7.0 mum was observed as gun atomization pressure increased from 6 to 10 psi. Overspray aerosols were sampled at two locations in the spray booth. A downstream sampling position simulated the exposure of a worker standing between the painted surface and exhaust, a situation encountered in booths with multiple workers. The measured mean MMAD was 7.2 mum. The distance between the painted surface and sampler was varied to sample oversprays of varying ages between 2.8 and 7.7 s. Age was not a significant factor for determining MMAD. Overspray was sampled at a 90 degrees position to simulate a worker standing in front of the surface being painted with air flowing to the worker's side, a common situation in field applications. The resulting overspray MMAD averaged 5.9 mum. Direct-spray aerosols were sampled at ages from 5.3 to 11.7 s. Overspray and direct-spray results indicated that most of the change in aerosol size distribution occurred between the time the paint aerosol impacted the painted surface and the time the overspray became 2.8 s old. The overall mean MMAD of overspray in the study was 6.4 mum and may have been underestimated due to sampling efficiency biases. If inhaled by a worker, the overspray aerosols evaluated in this study would mostly deposit in the head airways region of the respiratory tract. Paint overspray aerosols contained Cr primarily in the Cr(VI) state.","Size distribution of chromate paint aerosol generated in a bench-scale spray booth Abs: Spray painters are potentially exposed to aerosols containing hexavalent chromium [Cr(VI)] via inhalation of chromate-based paint sprays. Evaluating the particle size distribution of a paint spray aerosol, and the variables that may affect this distribution, is necessary to determine the site and degree of respiratory deposition and the damage that may result from inhaled Cr(VI)-containing paint particles. This study examined the effect of spray gun atomization pressure, aerosol generation source and aerosol aging on the size distribution of chromate-based paint overspray aerosols generated in a bench-scale paint spray booth. The study also determined the effect of particle bounce inside a Marple personal cascade impactor on measured size distributions of paint spray aerosols. Marple personal cascade impactors with a modified inlet were used for sample collection. The data indicated that paint particle bounce did not occur inside the cascade impactors sufficiently to affect size distribution when using uncoated stainless steel or PVC substrate sampling media. A decrease in paint aerosol mass median aerodynamic diameter (MMAD) from 8.2 to 7.0 mum was observed as gun atomization pressure increased from 6 to 10 psi. Overspray aerosols were sampled at two locations in the spray booth. A downstream sampling position simulated the exposure of a worker standing between the painted surface and exhaust, a situation encountered in booths with multiple workers. The measured mean MMAD was 7.2 mum. The distance between the painted surface and sampler was varied to sample oversprays of varying ages between 2.8 and 7.7 s. Age was not a significant factor for determining MMAD. Overspray was sampled at a 90 degrees position to simulate a worker standing in front of the surface being painted with air flowing to the worker's side, a common situation in field applications. The resulting overspray MMAD averaged 5.9 mum. Direct-spray aerosols were sampled at ages from 5.3 to 11.7 s. Overspray and direct-spray results indicated that most of the change in aerosol size distribution occurred between the time the paint aerosol impacted the painted surface and the time the overspray became 2.8 s old. The overall mean MMAD of overspray in the study was 6.4 mum and may have been underestimated due to sampling efficiency biases. If inhaled by a worker, the overspray aerosols evaluated in this study would mostly deposit in the head airways region of the respiratory tract. Paint overspray aerosols contained Cr primarily in the Cr(VI) state."
1233727,Puzon et al. 2005,Formation of soluble organo-chromium(III) complexes after chromate reduction in the presence of cellular organics,"Microbial reduction of hexavalent chromium [Cr(VI)] to trivalent chromium [Cr(III)] has been investigated as a method for bioremediation of Cr(VI) contaminated environments. The produced Cr(III) is thought to be insoluble Cr(OH)3; however, recent reports suggested a more complex fate of Cr(III). A bacterial enzyme system, using NADH as the reductant, converts Cr(VI)to a soluble NAD+-Cr(III) complex, and cytochrome c-mediated Cr(VI) reduction produces cytochrome c-Cr(III) adducts. In this study, Cr(VI) reduction in the presence of cellular organic metabolites formed both soluble and insoluble organo-Cr(III) end-products. Several soluble end-products were characterized by absorbance spectroscopy and electron paramagnetic resonance spectrometry as organo-Cr(III) complexes, similar to the known ascorbate-Cr(III) complex. The complexes remained soluble and stable upon dialysis against distilled H20 and over a broad pH range. The ready formation of stable organo-Cr(III) complexes suggests that organo-Cr(III) complexes are rather common, likely representing an integral part of the natural cycling of chromium. Thus, organo-Cr(III) complexes may account for the mobile form of Cr(II) detected in the environment.","Formation of soluble organo-chromium(III) complexes after chromate reduction in the presence of cellular organics Abs: Microbial reduction of hexavalent chromium [Cr(VI)] to trivalent chromium [Cr(III)] has been investigated as a method for bioremediation of Cr(VI) contaminated environments. The produced Cr(III) is thought to be insoluble Cr(OH)3; however, recent reports suggested a more complex fate of Cr(III). A bacterial enzyme system, using NADH as the reductant, converts Cr(VI)to a soluble NAD+-Cr(III) complex, and cytochrome c-mediated Cr(VI) reduction produces cytochrome c-Cr(III) adducts. In this study, Cr(VI) reduction in the presence of cellular organic metabolites formed both soluble and insoluble organo-Cr(III) end-products. Several soluble end-products were characterized by absorbance spectroscopy and electron paramagnetic resonance spectrometry as organo-Cr(III) complexes, similar to the known ascorbate-Cr(III) complex. The complexes remained soluble and stable upon dialysis against distilled H20 and over a broad pH range. The ready formation of stable organo-Cr(III) complexes suggests that organo-Cr(III) complexes are rather common, likely representing an integral part of the natural cycling of chromium. Thus, organo-Cr(III) complexes may account for the mobile form of Cr(II) detected in the environment."
1233725,Wilkin et al. 2005,Chromium-removal processes during groundwater remediation by a zerovalent iron permeable reactive barrier,"Solid-phase associations of chromium were examined in core materials collected from a full-scale, zerovalent iron permeable reactive barrier (PRB) at the U.S. Coast Guard Support Center located near Elizabeth City, NC. The PRB was installed in 1996 to treat groundwater contaminated with hexavalent chromium. After eight years of operation, the PRB remains effective at reducing concentrations of Cr from average values &gt;1500 microg L(-1) in groundwater hydraulically upgradient of the PRB to values &lt;1 microg L(-1) in groundwater within and hydraulically downgradient of the PRB. Chromium removal from groundwater occurs at the leading edge of the PRB and also within the aquifer immediately upgradient of the PRB. These regions also witness the greatest amount of secondary mineral formation due to steep geochemical gradients that result from the corrosion of zerovalent iron. X-ray absorption near-edge structure (XANES) spectroscopy indicated that chromium is predominantly in the trivalent oxidation state, confirming that reductive processes are responsible for Cr sequestration. XANES spectra and microscopy results suggest that Cr is, in part, associated with iron sulfide grains formed as a consequence of microbially mediated sulfate reduction in and around the PRB. Results of this study provide evidence that secondary iron-bearing mineral products may enhance the capacity of zerovalent iron systems to remediate Cr in groundwater, either through redox reactions at the mineral-water interface or by the release of Fe(II) to solution via mineral dissolution and/or metal corrosion.","Chromium-removal processes during groundwater remediation by a zerovalent iron permeable reactive barrier Abs: Solid-phase associations of chromium were examined in core materials collected from a full-scale, zerovalent iron permeable reactive barrier (PRB) at the U.S. Coast Guard Support Center located near Elizabeth City, NC. The PRB was installed in 1996 to treat groundwater contaminated with hexavalent chromium. After eight years of operation, the PRB remains effective at reducing concentrations of Cr from average values &gt;1500 microg L(-1) in groundwater hydraulically upgradient of the PRB to values &lt;1 microg L(-1) in groundwater within and hydraulically downgradient of the PRB. Chromium removal from groundwater occurs at the leading edge of the PRB and also within the aquifer immediately upgradient of the PRB. These regions also witness the greatest amount of secondary mineral formation due to steep geochemical gradients that result from the corrosion of zerovalent iron. X-ray absorption near-edge structure (XANES) spectroscopy indicated that chromium is predominantly in the trivalent oxidation state, confirming that reductive processes are responsible for Cr sequestration. XANES spectra and microscopy results suggest that Cr is, in part, associated with iron sulfide grains formed as a consequence of microbially mediated sulfate reduction in and around the PRB. Results of this study provide evidence that secondary iron-bearing mineral products may enhance the capacity of zerovalent iron systems to remediate Cr in groundwater, either through redox reactions at the mineral-water interface or by the release of Fe(II) to solution via mineral dissolution and/or metal corrosion."
1233724,Chen and  Gu 2005,Preliminary studies on continuous chromium(VI) biological removal from wastewater by anaerobic-aerobic activated sludge process,"The long-term continuous chromium(VI) removal from synthetic wastewater affected by influent hexavalent chromium (Cr(VI)) and glucose concentrations were studied with an anaerobic-aerobic activated sludge process. It was observed that before activated sludge was acclimated, the chromium in the effluent increased immediately as the influent chromium increased. However, both Cr(VI) and total chromium (TCr) in the effluent significantly decreased after acclimation. In the acclimated activated sludge, the chromium removal efficiency was 100% Cr(VI) and 98.56% TCr at influent Cr(VI) levels of 20 mg/day, 100% Cr(VI) and 98.92% TCr at influent Cr(VI) levels of 40 mg/day, and 98.64% Cr(VI) and 97.16% TCr at influent Cr(VI) levels of 60 mg/day. The corresponding effluent Cr(VI) and TCr concentrations were 0 and 0.012 mg/l, 0 and 0.018 mg/l, and 0.034 mg/l and 0.071 mg/l, respectively. When the influent glucose increased from 1125 to 1500 mg/l at influent Cr(VI) dosage of 60 mg/day, the Cr(VI) and TCr removal efficiency with the acclimated activated sludge improved from 98.64% and 97.16% to 100% and 98.48%, respectively, and the chromium concentration in the effluent decreased from 0.034 mg/l of Cr(VI) and 0.071 mg/l of TCr to 0 (Cr(VI)) and 0.038 mg/l (TCr). The effluent COD and turbidity was around 40 mg/l and 0, respectively, after the activated sludge was acclimated. Further studies showed that after the activated sludge was acclimated, its specific dehydrogenases activity (SDA) and protein contents increased. The SDA and protein increased respectively 15% and 10% when influent Cr(VI) increased from 20 to 60 mg/day.","Preliminary studies on continuous chromium(VI) biological removal from wastewater by anaerobic-aerobic activated sludge process Abs: The long-term continuous chromium(VI) removal from synthetic wastewater affected by influent hexavalent chromium (Cr(VI)) and glucose concentrations were studied with an anaerobic-aerobic activated sludge process. It was observed that before activated sludge was acclimated, the chromium in the effluent increased immediately as the influent chromium increased. However, both Cr(VI) and total chromium (TCr) in the effluent significantly decreased after acclimation. In the acclimated activated sludge, the chromium removal efficiency was 100% Cr(VI) and 98.56% TCr at influent Cr(VI) levels of 20 mg/day, 100% Cr(VI) and 98.92% TCr at influent Cr(VI) levels of 40 mg/day, and 98.64% Cr(VI) and 97.16% TCr at influent Cr(VI) levels of 60 mg/day. The corresponding effluent Cr(VI) and TCr concentrations were 0 and 0.012 mg/l, 0 and 0.018 mg/l, and 0.034 mg/l and 0.071 mg/l, respectively. When the influent glucose increased from 1125 to 1500 mg/l at influent Cr(VI) dosage of 60 mg/day, the Cr(VI) and TCr removal efficiency with the acclimated activated sludge improved from 98.64% and 97.16% to 100% and 98.48%, respectively, and the chromium concentration in the effluent decreased from 0.034 mg/l of Cr(VI) and 0.071 mg/l of TCr to 0 (Cr(VI)) and 0.038 mg/l (TCr). The effluent COD and turbidity was around 40 mg/l and 0, respectively, after the activated sludge was acclimated. Further studies showed that after the activated sludge was acclimated, its specific dehydrogenases activity (SDA) and protein contents increased. The SDA and protein increased respectively 15% and 10% when influent Cr(VI) increased from 20 to 60 mg/day."
1233721,Singh et al. 2005,Thermal stabilization of metal finishing waste with clay,"Thermal treatment of metal finishing waste with locally available clay, in their varying ratios, was carried out at 850 degrees C and above temperatures. In the presence of 1:1 ratio of waste and clay a solidified product was obtained at 950 degrees C. Measurement of an appreciably high compressive strength, approximately 500 kg cm(-2) and a very small (0.4%) water absorption from the solidified product indicated its stable nature. Toxicity Characteristic Leaching Procedure (TCLP) test of the waste showed nearly 85 to 90% decrease of leaching of Fe, Cu, Ni, Zn, Mn and Cr after thermal treatment compared to their leaching without treatment. No hexavalent chromium (Cr(VI)) was observed from the leachate of the solidified product. This indicates the absence of re-oxidation phenomena of chromium during thermal treatment up to 950 degrees C. X - ray diffraction (XRD) of solidified product indicated the presence of hematite, and aluminum silicate as main phases of the solidified product. Involvement of the above waste metals with these phases during thermal treatment could be the reason for their immobilization.","Thermal stabilization of metal finishing waste with clay Abs: Thermal treatment of metal finishing waste with locally available clay, in their varying ratios, was carried out at 850 degrees C and above temperatures. In the presence of 1:1 ratio of waste and clay a solidified product was obtained at 950 degrees C. Measurement of an appreciably high compressive strength, approximately 500 kg cm(-2) and a very small (0.4%) water absorption from the solidified product indicated its stable nature. Toxicity Characteristic Leaching Procedure (TCLP) test of the waste showed nearly 85 to 90% decrease of leaching of Fe, Cu, Ni, Zn, Mn and Cr after thermal treatment compared to their leaching without treatment. No hexavalent chromium (Cr(VI)) was observed from the leachate of the solidified product. This indicates the absence of re-oxidation phenomena of chromium during thermal treatment up to 950 degrees C. X - ray diffraction (XRD) of solidified product indicated the presence of hematite, and aluminum silicate as main phases of the solidified product. Involvement of the above waste metals with these phases during thermal treatment could be the reason for their immobilization."
1233720,Zhitkovich et al. 2005,Killing of chromium-damaged cells by mismatch repair and its relevance to carcinogenesis,"Hexavalent chromium compounds are widespread environmental contaminants that are well recognized as human carcinogens and potent respiratory toxicants. Intracellular metabolism of chromium(VI) leads to the production of numerous chromium-DNA adducts that are primarily formed at the phosphate groups. The mechanism of toxicity of these DNA modifications in human cells has been uncertain for a long time because chromium and other phosphate-based adducts did not block DNA replication with purified polymerases. Our recent studies identified mismatch repair proteins as activators of toxic responses to chromium-DNA damage, which resolved an apparent discrepancy in genotoxic activity of chromium adducts in cells and in vitro. The discovered mechanism of toxicity provided the basis for a novel model of chromium carcinogenesis based on the selection of resistant clones that lack mismatch repair and progress to cancer due to high levels of spontaneous mutagenesis.","Killing of chromium-damaged cells by mismatch repair and its relevance to carcinogenesis Abs: Hexavalent chromium compounds are widespread environmental contaminants that are well recognized as human carcinogens and potent respiratory toxicants. Intracellular metabolism of chromium(VI) leads to the production of numerous chromium-DNA adducts that are primarily formed at the phosphate groups. The mechanism of toxicity of these DNA modifications in human cells has been uncertain for a long time because chromium and other phosphate-based adducts did not block DNA replication with purified polymerases. Our recent studies identified mismatch repair proteins as activators of toxic responses to chromium-DNA damage, which resolved an apparent discrepancy in genotoxic activity of chromium adducts in cells and in vitro. The discovered mechanism of toxicity provided the basis for a novel model of chromium carcinogenesis based on the selection of resistant clones that lack mismatch repair and progress to cancer due to high levels of spontaneous mutagenesis."
1233719,Aruldhas et al. 2005,Chronic chromium exposure-induced changes in testicular histoarchitecture are associated with oxidative stress: study in a non-human primate (Macaca radiata Geoffroy),"<strong>BACKGROUND: </strong>Reproductive toxicity of chromium is in dispute despite positive findings in rodents. Recently we reported epididymal toxicity of hexavalent chromium (CrVI) in bonnet monkeys and in this paper we report its testicular toxicity.<br /><br /><strong>METHODS: </strong>Adult monkeys (Macaca radiata) were given drinking water containing CrVI (100, 200, 400 p.p.m.) for 6 months and testes were removed for ultrastructural and biochemical analyses.<br /><br /><strong>RESULTS: </strong>CrVI treatment disrupted spermatogenesis, leading to accumulation of prematurely released spermatocytes, spermatids and uni- and multinucleate giant cells in the lumen of seminiferous tubules. Transmission electron microscopy revealed granulation of chromatin and vacuolation between acrosomal cap and manchette microtubules of elongated spermatids and in the Golgi area of round spermatids. Pachytene spermatocytes had fragmented chromatin and swollen mitochondria with collapsed cristae. Spermatocytes and spermatogonia in the basal compartment were unaffected. Macrophages containing phagocytosed sperm and dense inclusions in Sertoli cells were seen. Specific activities of the antioxidant enzymes superoxide dismutase, catalase, glutathione peroxidase, glutathione reductase and glucose-6-phosphate dehydrogenase and concentrations of the non-enzymatic antioxidants glutathione, vitamins A, C and E decreased, while concentrations of H(2)O(2) and hydroxyl radicals increased in the testis of chromium-treated monkeys. Withdrawal of chromium treatment for 6 months normalized spermatogenesis and the status of pro- and antioxidants in the testis.<br /><br /><strong>CONCLUSIONS: </strong>CrVI disrupts spermatogenesis by inducing free radical toxicity, and supplementation of antioxidant vitamins may be beneficial to the affected subjects.","Chronic chromium exposure-induced changes in testicular histoarchitecture are associated with oxidative stress: study in a non-human primate (Macaca radiata Geoffroy) Abs: <strong>BACKGROUND: </strong>Reproductive toxicity of chromium is in dispute despite positive findings in rodents. Recently we reported epididymal toxicity of hexavalent chromium (CrVI) in bonnet monkeys and in this paper we report its testicular toxicity.<br /><br /><strong>METHODS: </strong>Adult monkeys (Macaca radiata) were given drinking water containing CrVI (100, 200, 400 p.p.m.) for 6 months and testes were removed for ultrastructural and biochemical analyses.<br /><br /><strong>RESULTS: </strong>CrVI treatment disrupted spermatogenesis, leading to accumulation of prematurely released spermatocytes, spermatids and uni- and multinucleate giant cells in the lumen of seminiferous tubules. Transmission electron microscopy revealed granulation of chromatin and vacuolation between acrosomal cap and manchette microtubules of elongated spermatids and in the Golgi area of round spermatids. Pachytene spermatocytes had fragmented chromatin and swollen mitochondria with collapsed cristae. Spermatocytes and spermatogonia in the basal compartment were unaffected. Macrophages containing phagocytosed sperm and dense inclusions in Sertoli cells were seen. Specific activities of the antioxidant enzymes superoxide dismutase, catalase, glutathione peroxidase, glutathione reductase and glucose-6-phosphate dehydrogenase and concentrations of the non-enzymatic antioxidants glutathione, vitamins A, C and E decreased, while concentrations of H(2)O(2) and hydroxyl radicals increased in the testis of chromium-treated monkeys. Withdrawal of chromium treatment for 6 months normalized spermatogenesis and the status of pro- and antioxidants in the testis.<br /><br /><strong>CONCLUSIONS: </strong>CrVI disrupts spermatogenesis by inducing free radical toxicity, and supplementation of antioxidant vitamins may be beneficial to the affected subjects."
1233718,Lazaridis et al. 2005,Sorptive removal of trivalent and hexavalent chromium from binary aqueous solutions by composite alginate-goethite beads,"In this study, the removal of hexavalent and trivalent chromium ions from binary aqueous solutions by composite alginate-goethite beads was investigated in a batch mode. Equilibrium sorption experiments were carried out at different temperatures and pH values. The data were correlated with Langmuir and Freundlich equations. The thermodynamic parameters calculated were: change in free energy, in enthalpy, in entropy and the heat of adsorption. The influence of mixing rate, sorbent concentration and sorbent particle size was studied at kinetic runs. The effective diffusion coefficients were evaluated by employing the homogeneous diffusion model and the shrinking core model for hexavalent and trivalent chromium, respectively. Desorption experiments were conducted by employing various eluants showed that the loaded material could be regenerated satisfactorily.","Sorptive removal of trivalent and hexavalent chromium from binary aqueous solutions by composite alginate-goethite beads Abs: In this study, the removal of hexavalent and trivalent chromium ions from binary aqueous solutions by composite alginate-goethite beads was investigated in a batch mode. Equilibrium sorption experiments were carried out at different temperatures and pH values. The data were correlated with Langmuir and Freundlich equations. The thermodynamic parameters calculated were: change in free energy, in enthalpy, in entropy and the heat of adsorption. The influence of mixing rate, sorbent concentration and sorbent particle size was studied at kinetic runs. The effective diffusion coefficients were evaluated by employing the homogeneous diffusion model and the shrinking core model for hexavalent and trivalent chromium, respectively. Desorption experiments were conducted by employing various eluants showed that the loaded material could be regenerated satisfactorily."
1233717,O'Brien et al. 2005,Hypoxia impedes the formation of chromium DNA-adducts in a cell-free system,"The metabolic reduction of hexavalent chromium [Cr(VI)] in the presence of DNA generates several lesions which impede DNA replication and gene transcription. However, the relative contribution of molecular oxygen to Cr-induced genetic damage is unclear. To elucidate the role of dioxygen in Cr genotoxicity, we studied the formation of Cr-induced lesions in DNA treated with either Cr(VI) and the physiological reductant, ascorbic acid (Asc), or Cr(III), under ambient and hypoxic (&lt;1% oxygen) conditions. We found that hypoxia did not impede the reduction of Cr(VI) by Asc throughout a 2 h treatment. In contrast, Cr-DNA binding under these conditions was reduced up to 70% by hypoxia, and a 50-90% decrease in the frequency of Cr-induced Taq polymerase-arresting DNA adducts was also observed. In the presence of Cr(VI)/Asc, formation of Cr-DNA interstrand crosslinks (ICLs) under hypoxia was 50% or less of that under ambient conditions. Kinetic studies found that hypoxia reduced the rate at which Cr interacted with DNA, but not the ultimate steady state level of Cr-DNA binding. The inhibitory effect of hypoxia on Cr(VI)/Asc genotoxicity could not be explained solely by alterations in the reactivity of intermediate Cr(V) species because Cr(III)-DNA binding and Cr(III)-induced ICL formation were also impaired by hypoxia. Moreover, Cr(V) was generated to similar levels in ambient and hypoxic reactions. Hypoxia did not affect ICL formation by the inorganic chemotherapeutic agent cisplatin, suggesting that these effects were specific for Cr(III). Taken together, these results support a role for dioxygen in facilitating the formation of Cr-DNA coordination complexes.","Hypoxia impedes the formation of chromium DNA-adducts in a cell-free system Abs: The metabolic reduction of hexavalent chromium [Cr(VI)] in the presence of DNA generates several lesions which impede DNA replication and gene transcription. However, the relative contribution of molecular oxygen to Cr-induced genetic damage is unclear. To elucidate the role of dioxygen in Cr genotoxicity, we studied the formation of Cr-induced lesions in DNA treated with either Cr(VI) and the physiological reductant, ascorbic acid (Asc), or Cr(III), under ambient and hypoxic (&lt;1% oxygen) conditions. We found that hypoxia did not impede the reduction of Cr(VI) by Asc throughout a 2 h treatment. In contrast, Cr-DNA binding under these conditions was reduced up to 70% by hypoxia, and a 50-90% decrease in the frequency of Cr-induced Taq polymerase-arresting DNA adducts was also observed. In the presence of Cr(VI)/Asc, formation of Cr-DNA interstrand crosslinks (ICLs) under hypoxia was 50% or less of that under ambient conditions. Kinetic studies found that hypoxia reduced the rate at which Cr interacted with DNA, but not the ultimate steady state level of Cr-DNA binding. The inhibitory effect of hypoxia on Cr(VI)/Asc genotoxicity could not be explained solely by alterations in the reactivity of intermediate Cr(V) species because Cr(III)-DNA binding and Cr(III)-induced ICL formation were also impaired by hypoxia. Moreover, Cr(V) was generated to similar levels in ambient and hypoxic reactions. Hypoxia did not affect ICL formation by the inorganic chemotherapeutic agent cisplatin, suggesting that these effects were specific for Cr(III). Taken together, these results support a role for dioxygen in facilitating the formation of Cr-DNA coordination complexes."
1233716,Fatima et al. 2005,Effect of potassium dichromate on renal brush border membrane enzymes and phosphate transport in rats,"Chromium is widely used in industry but exposure to chromium compounds in the workplace can result in nephrotoxicity. Various nephrotoxicants affect the brush border membrane (BBM) lining the epithelial cells of the proximal tubule, but there have been no studies regarding the effect of potassium dichromate (K2Cr2O7), a hexavalent chromium compound, on renal BBM. In the present work, the effect of administering a single intraperitoneal dose (15 mg/kg body weight) of K2Cr2O7 on rat renal BBM enzymes and inorganic phosphate (Pi) transport was studied. The animals were administered normal saline (control) or K2Cr2O7 and sacrificed 1, 2, 4 and 8 days after treatment. K2Cr2O7 induced reversible damage to the rat kidney function as indicated by serum creatinine (Scr) and urea nitrogen levels. The activities of BBM marker enzymes were significantly decreased in isolated BBM vesicles (BBMV) and homogenates of cortex and medulla on 1, 2 and 4 days after administration of K2Cr2O7 with complete recovery to control values after 8 days. The decrease in the activities of the enzymes was mainly due to changes in maximum velocity (V(max)) values, while the Michaelis constant (Km) remained unchanged. The sodium dependent Pi transport across BBMV was reduced by 50% after treatment with K2Cr2O7. Thus, the administration of a single dose of K2Cr2O7 leads to impairment in the functions of renal BBM. These results suggest that the nephrotoxicity of K2Cr2O7 may be mediated, at least in part, by its effect on renal BBM.","Effect of potassium dichromate on renal brush border membrane enzymes and phosphate transport in rats Abs: Chromium is widely used in industry but exposure to chromium compounds in the workplace can result in nephrotoxicity. Various nephrotoxicants affect the brush border membrane (BBM) lining the epithelial cells of the proximal tubule, but there have been no studies regarding the effect of potassium dichromate (K2Cr2O7), a hexavalent chromium compound, on renal BBM. In the present work, the effect of administering a single intraperitoneal dose (15 mg/kg body weight) of K2Cr2O7 on rat renal BBM enzymes and inorganic phosphate (Pi) transport was studied. The animals were administered normal saline (control) or K2Cr2O7 and sacrificed 1, 2, 4 and 8 days after treatment. K2Cr2O7 induced reversible damage to the rat kidney function as indicated by serum creatinine (Scr) and urea nitrogen levels. The activities of BBM marker enzymes were significantly decreased in isolated BBM vesicles (BBMV) and homogenates of cortex and medulla on 1, 2 and 4 days after administration of K2Cr2O7 with complete recovery to control values after 8 days. The decrease in the activities of the enzymes was mainly due to changes in maximum velocity (V(max)) values, while the Michaelis constant (Km) remained unchanged. The sodium dependent Pi transport across BBMV was reduced by 50% after treatment with K2Cr2O7. Thus, the administration of a single dose of K2Cr2O7 leads to impairment in the functions of renal BBM. These results suggest that the nephrotoxicity of K2Cr2O7 may be mediated, at least in part, by its effect on renal BBM."
1233715,Xu and  Jaffé 2006,Effects of plants on the removal of hexavalent chromium in wetland sediments,"The effect of two wetland plants, Typha latifolia L. (cattail) and Phragmites australis (Cav.) Trin. ex Steud (common reed), on the fate of Cr(VI) in wetland sediments was investigated using greenhouse bench-scale microcosm experiments. The removal of Cr(VI) was monitored based on the vertical profiles of aqueous Cr(VI) in the sediments. The Cr(VI) removal rates were estimated taking into account plant transpiration, which was found to significantly concentrate dissolved species in the sediments. After correcting for evapotranspiration, the actual Cr(VI) removal rates were significantly higher than would be inferred from uncorrected profiles. On average, the Cr(VI) removal rates were 0.005 to 0.017 mg L(-1) d(-1), 0.0003 to 0.08 mg L(-1) d(-1), and 0.004 to 0.13 mg L(-1) d(-1) for the control, T. latifolia, and P. australis microcosms, respectively. The fate of the removed Cr(VI) was examined by determining the quantity and chemical speciation of the Cr in the sediment and plant materials. Chromium(III) was the dominant form of Cr in both the sediment and plants, and precipitation of Cr(III) in the sediment was the major pathway responsible for the disappearance of aqueous Cr(VI) from the pore water. Incubation results showed that abiotic reduction was the primary mechanism underlying Cr(VI) removal in the microcosm sediments. Organic compounds produced by plants, including root exudates and mineralization products of dead roots, are thought to be the factor that is either directly or indirectly responsible for the gap between Cr(VI) removal efficiencies in the sediments of the vegetated and unvegetated microcosms.","Effects of plants on the removal of hexavalent chromium in wetland sediments Abs: The effect of two wetland plants, Typha latifolia L. (cattail) and Phragmites australis (Cav.) Trin. ex Steud (common reed), on the fate of Cr(VI) in wetland sediments was investigated using greenhouse bench-scale microcosm experiments. The removal of Cr(VI) was monitored based on the vertical profiles of aqueous Cr(VI) in the sediments. The Cr(VI) removal rates were estimated taking into account plant transpiration, which was found to significantly concentrate dissolved species in the sediments. After correcting for evapotranspiration, the actual Cr(VI) removal rates were significantly higher than would be inferred from uncorrected profiles. On average, the Cr(VI) removal rates were 0.005 to 0.017 mg L(-1) d(-1), 0.0003 to 0.08 mg L(-1) d(-1), and 0.004 to 0.13 mg L(-1) d(-1) for the control, T. latifolia, and P. australis microcosms, respectively. The fate of the removed Cr(VI) was examined by determining the quantity and chemical speciation of the Cr in the sediment and plant materials. Chromium(III) was the dominant form of Cr in both the sediment and plants, and precipitation of Cr(III) in the sediment was the major pathway responsible for the disappearance of aqueous Cr(VI) from the pore water. Incubation results showed that abiotic reduction was the primary mechanism underlying Cr(VI) removal in the microcosm sediments. Organic compounds produced by plants, including root exudates and mineralization products of dead roots, are thought to be the factor that is either directly or indirectly responsible for the gap between Cr(VI) removal efficiencies in the sediments of the vegetated and unvegetated microcosms."
1233714,Arreola-Mendoza et al. 2006,Alpha-tocopherol protects against the renal damage caused by potassium dichromate,"Exposure to hexavalent chromium (Cr(6+)) causes mutagenic, carcinogenic, and toxic effects, some of which have been associated with its oxidative capacity. In the kidney, Cr(6+) has been claimed to provoke necrosis of the proximal tubular cells. Our aim was to assess the functional involvement of the different segments that form the nephron in a model of acute renal failure caused by potassium dichromate and the participation of oxidative damage in this process. We also studied the possible protective effect of alpha-tocopherol (alpha-TOC) against renal damage. Wistar female rats 200g body weight (bw) received potassium dichromate (15mg/kg, sc, single dose). Lipid peroxidation and renal function were evaluated on days 0, 1, 2, 3, 7, 10, and 14. A second group received alpha-TOC (125mg/kg, by gavage) 5 days before and during dichromate exposure (same dose as for the first group), and was monitored at 0, 2, and 7 days of exposure. Creatinine clearance, glucose and sodium fractional excretions, p-aminohippurate uptake, free-water and osmolal clearances were also measured. Thiobarbituric acid-reactive substances were quantified in renal cortex. The results revealed altered proximal tubule function, decreased glomerular filtration, and distal segment dysfunction, accompanied by oxidative damage 48h after exposure to dichromate. In the alpha-TOC-treated group proximal reabsorptive and secretory functions were preserved, suggesting that oxidative damage is a participating mechanism in dichromate toxicity on these functions. In contrast alpha-TOC did not prevent glomerular or distal dysfunction, indicating selectivity of the protection afforded by this compound on the toxicity of dichromate, at the several components of the nephron.","Alpha-tocopherol protects against the renal damage caused by potassium dichromate Abs: Exposure to hexavalent chromium (Cr(6+)) causes mutagenic, carcinogenic, and toxic effects, some of which have been associated with its oxidative capacity. In the kidney, Cr(6+) has been claimed to provoke necrosis of the proximal tubular cells. Our aim was to assess the functional involvement of the different segments that form the nephron in a model of acute renal failure caused by potassium dichromate and the participation of oxidative damage in this process. We also studied the possible protective effect of alpha-tocopherol (alpha-TOC) against renal damage. Wistar female rats 200g body weight (bw) received potassium dichromate (15mg/kg, sc, single dose). Lipid peroxidation and renal function were evaluated on days 0, 1, 2, 3, 7, 10, and 14. A second group received alpha-TOC (125mg/kg, by gavage) 5 days before and during dichromate exposure (same dose as for the first group), and was monitored at 0, 2, and 7 days of exposure. Creatinine clearance, glucose and sodium fractional excretions, p-aminohippurate uptake, free-water and osmolal clearances were also measured. Thiobarbituric acid-reactive substances were quantified in renal cortex. The results revealed altered proximal tubule function, decreased glomerular filtration, and distal segment dysfunction, accompanied by oxidative damage 48h after exposure to dichromate. In the alpha-TOC-treated group proximal reabsorptive and secretory functions were preserved, suggesting that oxidative damage is a participating mechanism in dichromate toxicity on these functions. In contrast alpha-TOC did not prevent glomerular or distal dysfunction, indicating selectivity of the protection afforded by this compound on the toxicity of dichromate, at the several components of the nephron."
1233713,Long et al. 2006,On-line dynamic extraction and automated determination of readily bioavailable hexavalent chromium in solid substrates using micro-sequential injection bead-injection lab-on-valve hyphenated with electrothermal atomic absorption spectrometry,"A novel and miniaturized micro-sequential injection bead-injection lab-on-valve (microSI-BI-LOV) fractionation system was developed for on-line microcolumn soil extraction under simulated environmental scenarios and accurate monitoring of the content of easily mobilisable hexavalent chromium in soil environments at the sub-low parts-per-million level. The flow system integrates dynamic leaching of hexavalent chromium using deionized water as recommended by the German Standard DIN 38414-S4 method; on-line pH adjustment of the extract by a 0.01 mol L(-1) Tris-HNO(3) buffer solution; isolation of the chromate leached from the matrix constituents onto a Q Sepharose strong anion-exchanger freshly packed into the microconduits of the microSI-assembly; air-segmented elution of the sorbed species by a 40 microL plug of 0.5 mol L(-1) NH(4)NO(3) (pH 8) eluent; and detection by electrothermal atomic absorption spectrometry (ETAAS). The effect of simulated acidic rain on the accessibility of chromate forms for plant uptake was also investigated. The proposed approach offers several advantages over conventional speciation/fractionation protocols in the batch mode, including immediate separation with concomitant preconcentration of the released chromate, minimization of Cr(vi) to Cr(iii) interconversion risks, enhanced accuracy, and non-existence of re-adsorption/re-distribution problems along with a detailed pattern of the kinetics of the leaching process. The reliability of the proposed method was evaluated via spiking of a moderately polluted agricultural soil material (San Joaquin Soil-Baseline Trace Element Concentrations) with water-soluble Cr(vi) salts at different concentration levels. The potential of the microSI-BI-LOV set-up with renewable surfaces for flame-AAS determination of high levels of readily bioavailable chromate in contaminated soils is also addressed.","On-line dynamic extraction and automated determination of readily bioavailable hexavalent chromium in solid substrates using micro-sequential injection bead-injection lab-on-valve hyphenated with electrothermal atomic absorption spectrometry Abs: A novel and miniaturized micro-sequential injection bead-injection lab-on-valve (microSI-BI-LOV) fractionation system was developed for on-line microcolumn soil extraction under simulated environmental scenarios and accurate monitoring of the content of easily mobilisable hexavalent chromium in soil environments at the sub-low parts-per-million level. The flow system integrates dynamic leaching of hexavalent chromium using deionized water as recommended by the German Standard DIN 38414-S4 method; on-line pH adjustment of the extract by a 0.01 mol L(-1) Tris-HNO(3) buffer solution; isolation of the chromate leached from the matrix constituents onto a Q Sepharose strong anion-exchanger freshly packed into the microconduits of the microSI-assembly; air-segmented elution of the sorbed species by a 40 microL plug of 0.5 mol L(-1) NH(4)NO(3) (pH 8) eluent; and detection by electrothermal atomic absorption spectrometry (ETAAS). The effect of simulated acidic rain on the accessibility of chromate forms for plant uptake was also investigated. The proposed approach offers several advantages over conventional speciation/fractionation protocols in the batch mode, including immediate separation with concomitant preconcentration of the released chromate, minimization of Cr(vi) to Cr(iii) interconversion risks, enhanced accuracy, and non-existence of re-adsorption/re-distribution problems along with a detailed pattern of the kinetics of the leaching process. The reliability of the proposed method was evaluated via spiking of a moderately polluted agricultural soil material (San Joaquin Soil-Baseline Trace Element Concentrations) with water-soluble Cr(vi) salts at different concentration levels. The potential of the microSI-BI-LOV set-up with renewable surfaces for flame-AAS determination of high levels of readily bioavailable chromate in contaminated soils is also addressed."
1233711,Apte et al. 2006,Extent of oxidation of Cr(III) to Cr(VI) under various conditions pertaining to natural environment,"Calculations show that oxidation of chromium oxide (Cr2O3) by oxygen and oxidation of chromium hydroxide (Cr(OH)3) by manganese dioxide (MnO2) are thermodynamically feasible in both aerobic and mildly anoxic environments. Experiments were carried out to determine the rate and extent of chromium oxidation under various conditions, i.e., when Cr2O3 was heated in the presence of oxygen, when Cr(OH)3 and MnO2 mixtures were suspended in aerobic or anoxic aqueous media at various pH values, when Cr(OH)3 and MnO2 mixtures interacted in moist aerobic conditions and when chromium assumed to be Cr(OH)3 and manganese assumed to be MnO2 interacted in the presence of competing electron donors/acceptors, as is the case in chromium-contaminated sludge. Results indicate that trivalent chromium in Cr2O3 could be readily converted to hexavalent chromium at a temperature range of 200-300 degrees C, with conversion rates of up to 50% in 12 h. In aqueous media, Cr(OH)3 was slowly converted to dissolved Cr(VI) in the presence of MnO2, both in aerobic and anoxic conditions, with conversion rates of up to 1% in 60 days. In moist aerobic conditions and in the presence of MnO2, Cr(OH)(3) slowly converted to hexavalent chromium, with up to 0.05% conversion observed in 90 days. Chromium oxidation also occurred in sludge samples, especially under aerobic conditions. However, such transformation was found to be transitory, with the Cr(VI) formed being ultimately reduced back to Cr(III) due to the presence of various reducing agents in the sludge. Nevertheless since up to 17% conversion of Cr(III) to Cr(VI) occurred in sludge under aerobic conditions by 30 days, there is real danger under field conditions of spreading Cr(VI) pollution due to possible intervening rainfall, runoff and percolation.","Extent of oxidation of Cr(III) to Cr(VI) under various conditions pertaining to natural environment Abs: Calculations show that oxidation of chromium oxide (Cr2O3) by oxygen and oxidation of chromium hydroxide (Cr(OH)3) by manganese dioxide (MnO2) are thermodynamically feasible in both aerobic and mildly anoxic environments. Experiments were carried out to determine the rate and extent of chromium oxidation under various conditions, i.e., when Cr2O3 was heated in the presence of oxygen, when Cr(OH)3 and MnO2 mixtures were suspended in aerobic or anoxic aqueous media at various pH values, when Cr(OH)3 and MnO2 mixtures interacted in moist aerobic conditions and when chromium assumed to be Cr(OH)3 and manganese assumed to be MnO2 interacted in the presence of competing electron donors/acceptors, as is the case in chromium-contaminated sludge. Results indicate that trivalent chromium in Cr2O3 could be readily converted to hexavalent chromium at a temperature range of 200-300 degrees C, with conversion rates of up to 50% in 12 h. In aqueous media, Cr(OH)3 was slowly converted to dissolved Cr(VI) in the presence of MnO2, both in aerobic and anoxic conditions, with conversion rates of up to 1% in 60 days. In moist aerobic conditions and in the presence of MnO2, Cr(OH)(3) slowly converted to hexavalent chromium, with up to 0.05% conversion observed in 90 days. Chromium oxidation also occurred in sludge samples, especially under aerobic conditions. However, such transformation was found to be transitory, with the Cr(VI) formed being ultimately reduced back to Cr(III) due to the presence of various reducing agents in the sludge. Nevertheless since up to 17% conversion of Cr(III) to Cr(VI) occurred in sludge under aerobic conditions by 30 days, there is real danger under field conditions of spreading Cr(VI) pollution due to possible intervening rainfall, runoff and percolation."
1233710,Song et al. 2006,Implication of chromium speciation on disposal of discarded CCA-treated wood,"The wood preservative chromated copper arsenate (CCA) contains hexavalent chromium [Cr(VI)] and the conversion of Cr(VI) to trivalent chromium [Cr(III)] drives fixation of the treatment chemicals to the wood fibers. Since the toxicity of Cr depends on its valence state, an assessment of the Cr species occurring in CCA-treated wood, as well as leachates and ashes from CCA-treated wood, is helpful when assessing implications for disposal. In this study, both new and weathered wood samples of CCA-treated wood and their ashes were evaluated for total Cr and Cr(VI) within the solid matrices and within leachates. Results show that for both new and weathered CCA-treated wood, Cr(VI) occurred in the range of 0.7-4% of the total Cr. Greater Cr leaching occurred at the pH extremes, with Cr(VI) only measured under alkaline pH values (pH &gt; 9.0). Total chromium concentrations from synthetic precipitation leaching procedure (SPLP) leachates from CCA-treated wood were consistently less than 3mg/L with Cr(VI) below detection limits. The results suggest that leaching of Cr(VI) from discarded CCA-treated wood should not be a concern in most landfill environments. One exception would be disposal in landfills with alkaline leachate; Cr(VI) was observed to leach from CCA-treated wood in the presence of alkaline leachate from crushed concrete. When CCA-treated wood is combusted, chromium becomes concentrated in the ash. Cr(VI) in ash from the combustion of CCA-treated wood was found between 4 and 7% of the total chromium. In ash from the combustion of wood recovered from construction and demolition (C&amp;D) debris (which contained some CCA-treated wood), Cr(VI) accounted for as much as 43% of the total Cr. Nearly, all of the Cr in SPLP leachates produced from the ash was in the Cr(VI) form. The degree of Cr(VI) leaching from the ash was highly dependent upon the alkalinity of the ash, with higher ash leachate pH resulting in greater concentrations of Cr(VI).","Implication of chromium speciation on disposal of discarded CCA-treated wood Abs: The wood preservative chromated copper arsenate (CCA) contains hexavalent chromium [Cr(VI)] and the conversion of Cr(VI) to trivalent chromium [Cr(III)] drives fixation of the treatment chemicals to the wood fibers. Since the toxicity of Cr depends on its valence state, an assessment of the Cr species occurring in CCA-treated wood, as well as leachates and ashes from CCA-treated wood, is helpful when assessing implications for disposal. In this study, both new and weathered wood samples of CCA-treated wood and their ashes were evaluated for total Cr and Cr(VI) within the solid matrices and within leachates. Results show that for both new and weathered CCA-treated wood, Cr(VI) occurred in the range of 0.7-4% of the total Cr. Greater Cr leaching occurred at the pH extremes, with Cr(VI) only measured under alkaline pH values (pH &gt; 9.0). Total chromium concentrations from synthetic precipitation leaching procedure (SPLP) leachates from CCA-treated wood were consistently less than 3mg/L with Cr(VI) below detection limits. The results suggest that leaching of Cr(VI) from discarded CCA-treated wood should not be a concern in most landfill environments. One exception would be disposal in landfills with alkaline leachate; Cr(VI) was observed to leach from CCA-treated wood in the presence of alkaline leachate from crushed concrete. When CCA-treated wood is combusted, chromium becomes concentrated in the ash. Cr(VI) in ash from the combustion of CCA-treated wood was found between 4 and 7% of the total chromium. In ash from the combustion of wood recovered from construction and demolition (C&amp;D) debris (which contained some CCA-treated wood), Cr(VI) accounted for as much as 43% of the total Cr. Nearly, all of the Cr in SPLP leachates produced from the ash was in the Cr(VI) form. The degree of Cr(VI) leaching from the ash was highly dependent upon the alkalinity of the ash, with higher ash leachate pH resulting in greater concentrations of Cr(VI)."
1233709,OSHA 2006,Occupational exposure to hexavalent chromium. Final rule,"The Occupational Safety and Health Administration (OSHA) is amending the existing standard which limits occupational exposure to hexavalent chromium (Cr(VI)). OSHA has determined based upon the best evidence currently available that at the current permissible exposure limit (PEL) for Cr(VI), workers face a significant risk to material impairment of their health. The evidence in the record for this rulemaking indicates that workers exposed to Cr(VI) are at an increased risk of developing lung cancer. The record also indicates that occupational exposure to Cr(VI) may result in asthma, and damage to the nasal epithelia and skin. The final rule establishes an 8-hour time-weighted average (TWA) exposure limit of 5 micrograms of Cr(VI) per cubic meter of air (5 [mu]g/cu m). This is a considerable reduction from the previous PEL of 1 milligram per 10 cubic meters of air (1 mg/10 cu m, or 100 [mu]g/cu m) reported as CrO3, which is equivalent to a limit of 52 [mu]g/cu m as Cr(VI). The final rule also contains ancillary provisions for worker protection such as requirements for exposure determination, preferred exposure control methods, including a compliance alternative for a small sector for which the new PEL is infeasible, respiratory protection, protective clothing and equipment, hygiene areas and practices, medical surveillance, recordkeeping, and start-up dates that include four years for the implementation of engineering controls to meet the PEL. The final standard separately regulates general industry, construction, and shipyards in order to tailor requirements to the unique circumstances found in each of these sectors. The PEL established by this rule reduces the significant risk posed to workers by occupational exposure to Cr(VI) to the maximum extent that is technologically and economically feasible.","Occupational exposure to hexavalent chromium. Final rule Abs: The Occupational Safety and Health Administration (OSHA) is amending the existing standard which limits occupational exposure to hexavalent chromium (Cr(VI)). OSHA has determined based upon the best evidence currently available that at the current permissible exposure limit (PEL) for Cr(VI), workers face a significant risk to material impairment of their health. The evidence in the record for this rulemaking indicates that workers exposed to Cr(VI) are at an increased risk of developing lung cancer. The record also indicates that occupational exposure to Cr(VI) may result in asthma, and damage to the nasal epithelia and skin. The final rule establishes an 8-hour time-weighted average (TWA) exposure limit of 5 micrograms of Cr(VI) per cubic meter of air (5 [mu]g/cu m). This is a considerable reduction from the previous PEL of 1 milligram per 10 cubic meters of air (1 mg/10 cu m, or 100 [mu]g/cu m) reported as CrO3, which is equivalent to a limit of 52 [mu]g/cu m as Cr(VI). The final rule also contains ancillary provisions for worker protection such as requirements for exposure determination, preferred exposure control methods, including a compliance alternative for a small sector for which the new PEL is infeasible, respiratory protection, protective clothing and equipment, hygiene areas and practices, medical surveillance, recordkeeping, and start-up dates that include four years for the implementation of engineering controls to meet the PEL. The final standard separately regulates general industry, construction, and shipyards in order to tailor requirements to the unique circumstances found in each of these sectors. The PEL established by this rule reduces the significant risk posed to workers by occupational exposure to Cr(VI) to the maximum extent that is technologically and economically feasible."
1233707,Birk et al. 2006,"Lung cancer mortality in the German chromate industry, 1958 to 1998","<strong>OBJECTIVES: </strong>We conducted a mortality study of two German chromate production facilities and evaluated possible dose-response relationships between hexavalent chromium exposure and lung cancer.<br /><br /><strong>METHODS: </strong>Mortality was followed-up through 1998 and limited to those employed since each plant converted to a no-lime production process. More than 12,000 urinalysis results of chromium levels were available, as was smoking information.<br /><br /><strong>RESULTS: </strong>All-cause mortality indicated a healthy worker effect (standardized mortality ratio [SMR] = 0.80, 95% confidence interval [CI] = 0.67-0.96); however, lung cancers appeared to be increased (SMR = 1.48, 95% CI = 0.93-2.25). No clear dose-response was found in stratified analyses by duration of employment and time since hire. On the basis of urinary chromium data, lung cancer risk was elevated only in the highest exposure group (SMR = 2.09, 95% CI = 1.08-3.65).<br /><br /><strong>CONCLUSIONS: </strong>These data suggest a possible threshold effect of occupational hexavalent chromium exposure on lung cancer.","Lung cancer mortality in the German chromate industry, 1958 to 1998 Abs: <strong>OBJECTIVES: </strong>We conducted a mortality study of two German chromate production facilities and evaluated possible dose-response relationships between hexavalent chromium exposure and lung cancer.<br /><br /><strong>METHODS: </strong>Mortality was followed-up through 1998 and limited to those employed since each plant converted to a no-lime production process. More than 12,000 urinalysis results of chromium levels were available, as was smoking information.<br /><br /><strong>RESULTS: </strong>All-cause mortality indicated a healthy worker effect (standardized mortality ratio [SMR] = 0.80, 95% confidence interval [CI] = 0.67-0.96); however, lung cancers appeared to be increased (SMR = 1.48, 95% CI = 0.93-2.25). No clear dose-response was found in stratified analyses by duration of employment and time since hire. On the basis of urinary chromium data, lung cancer risk was elevated only in the highest exposure group (SMR = 2.09, 95% CI = 1.08-3.65).<br /><br /><strong>CONCLUSIONS: </strong>These data suggest a possible threshold effect of occupational hexavalent chromium exposure on lung cancer."
1233706,Baral et al. 2006,Evaluation of aquatic toxicities of chromium and chromium-containing effluents in reference to chromium electroplating industries,"This study evaluated aquatic toxicities of chromium and chromium-containing laboratory samples representative of effluents from chromium electroplating industries, and compared the aquatic environmental risks of hexavalent and trivalent chromium electroplating operations. Trivalent chromium electroplating has emerged as an acceptable alternative to hazardous hexavalent chromium electroplating. This process substitution has reduced the human health impact in the workplace and minimized the production of hazardous sludge regulated under the Resource Conservation and Recovery Act (RCRA). The thrust behind this research was to investigate whether trivalent chromium electroplating operations have lower adverse impacts on standardized toxicity test organisms. Ceriodaphnia dubia and Pimephales promelas were used to investigate toxicities of trivalent chromium (Cr (III)), hexavalent chromium (Cr (VI)), and industrial effluents. In agreement with previous studies, Cr (III) was found to be less toxic than Cr (VI). Despite having several organic and inorganic constituents in the effluents obtained from trivalent chromium plating baths, they exhibited less adverse effects to C. dubia than effluents obtained from hexavalent chromium electroplating baths. Thus, transition from hexavalent to trivalent chromium electroplating processes may be justified. However, because of the presence of organic constituents such as formate, oxalate, and triethylene glycol in effluents, trivalent chromium electroplating operations may face additional regulatory requirements for removal of total organic carbon.","Evaluation of aquatic toxicities of chromium and chromium-containing effluents in reference to chromium electroplating industries Abs: This study evaluated aquatic toxicities of chromium and chromium-containing laboratory samples representative of effluents from chromium electroplating industries, and compared the aquatic environmental risks of hexavalent and trivalent chromium electroplating operations. Trivalent chromium electroplating has emerged as an acceptable alternative to hazardous hexavalent chromium electroplating. This process substitution has reduced the human health impact in the workplace and minimized the production of hazardous sludge regulated under the Resource Conservation and Recovery Act (RCRA). The thrust behind this research was to investigate whether trivalent chromium electroplating operations have lower adverse impacts on standardized toxicity test organisms. Ceriodaphnia dubia and Pimephales promelas were used to investigate toxicities of trivalent chromium (Cr (III)), hexavalent chromium (Cr (VI)), and industrial effluents. In agreement with previous studies, Cr (III) was found to be less toxic than Cr (VI). Despite having several organic and inorganic constituents in the effluents obtained from trivalent chromium plating baths, they exhibited less adverse effects to C. dubia than effluents obtained from hexavalent chromium electroplating baths. Thus, transition from hexavalent to trivalent chromium electroplating processes may be justified. However, because of the presence of organic constituents such as formate, oxalate, and triethylene glycol in effluents, trivalent chromium electroplating operations may face additional regulatory requirements for removal of total organic carbon."
1233704,Sedman et al. 2006,Review of the evidence regarding the carcinogenicity of hexavalent chromium in drinking water,"Recent analyses have revealed that 38% of municipal sources of drinking water in California have detectable levels of hexavalent chromium. This observation provided new impetus to characterize the carcinogenic risk associated with oral exposure to hexavalent chromium in drinking water. Notwithstanding the well-characterized increases in cancer associated with inhalation exposure to this chemical, the marked reduction of hexavalent chromium to trivalent chromium in the stomach suggests that exposure to hexavalent chromium in drinking water may not pose a carcinogenic risk. A reevaluation of studies that investigated the toxicokinetics, the genotoxicity, and the mechanism of carcinogenicity of hexavalent chromium, as well as the available human and animal cancer studies, was undertaken to determine if there is evidence that exposure to this chemical in drinking water may pose a carcinogenic risk. Mechanistic studies suggest the potential for a carcinogenic response if hexavalent chromium enters cells. Both toxicokinetic and genotoxicity studies indicate that a portion of an orally administered dose of hexavalent chromium is absorbed and gets into cells of several tissues, causing DNA damage. The only lifetime oral study of hexavalent chromium in animals conducted thus far yielded a statistically significant increase in stomach tumors compared to controls. Also, in a limited-term cancer study, co-exposure to hexavalent chromium in drinking water and ultraviolet light produced skin tumors in mice. The only available cancer study of humans exposed to hexavalent chromium in drinking water revealed a statistically significant increase in stomach tumors. Moreover, a meta-analysis of occupational studies also revealed a statistically significant increase in stomach cancers. The increases in stomach tumors in both human and animal studies, along with the toxicokinetic, genotoxic, and mechanistic data, suggest that oral exposure to this agent appears to pose a carcinogenic risk.","Review of the evidence regarding the carcinogenicity of hexavalent chromium in drinking water Abs: Recent analyses have revealed that 38% of municipal sources of drinking water in California have detectable levels of hexavalent chromium. This observation provided new impetus to characterize the carcinogenic risk associated with oral exposure to hexavalent chromium in drinking water. Notwithstanding the well-characterized increases in cancer associated with inhalation exposure to this chemical, the marked reduction of hexavalent chromium to trivalent chromium in the stomach suggests that exposure to hexavalent chromium in drinking water may not pose a carcinogenic risk. A reevaluation of studies that investigated the toxicokinetics, the genotoxicity, and the mechanism of carcinogenicity of hexavalent chromium, as well as the available human and animal cancer studies, was undertaken to determine if there is evidence that exposure to this chemical in drinking water may pose a carcinogenic risk. Mechanistic studies suggest the potential for a carcinogenic response if hexavalent chromium enters cells. Both toxicokinetic and genotoxicity studies indicate that a portion of an orally administered dose of hexavalent chromium is absorbed and gets into cells of several tissues, causing DNA damage. The only lifetime oral study of hexavalent chromium in animals conducted thus far yielded a statistically significant increase in stomach tumors compared to controls. Also, in a limited-term cancer study, co-exposure to hexavalent chromium in drinking water and ultraviolet light produced skin tumors in mice. The only available cancer study of humans exposed to hexavalent chromium in drinking water revealed a statistically significant increase in stomach tumors. Moreover, a meta-analysis of occupational studies also revealed a statistically significant increase in stomach cancers. The increases in stomach tumors in both human and animal studies, along with the toxicokinetic, genotoxic, and mechanistic data, suggest that oral exposure to this agent appears to pose a carcinogenic risk."
1233703,Martínez-Jerónimo et al. 2006,Effect of culture conditions and mother's age on the sensitivity of Daphnia magna Straus 1820 (Cladocera) neonates to hexavalent chromium,"Daphnia magna is a freshwater cladoceran used worldwide as test organism in aquatic toxicity assays. In Mexico there is a test protocol for this species; nevertheless, some aspects of the controlled neonate production, as well as the possible consequences of the reproducers' culture conditions on the response of neonates to the toxic substance, are not completely known. In the present study, we evaluated the effect of temperature and photoperiod on the acute toxicity of CrVI in D. magna neonates, aimed at providing useful information on the Median Lethal Concentration (LC50) to this heavy metal, which is used as reference toxicant in some laboratories. D. magna was cultured at 20 and 25 degrees C, in combination with two photoperiod values: 16:8 and 12:12 (light:dark) during 40 days; the green microalga Ankistrodesmus falcatus (4x10(5) cells ml(-1)) was supplied as food. Once the reproduction began, the neonates were removed and acute toxicity bioassays at 20 and 25 degrees C were performed, by exposing them to hexavalent chromium. We also determined changes in neonates' size at 20 and 25 degrees C. Chromium toxicity increased along with increasing temperatures, and LC50 values were slightly lower for the first and last clutches in the observed period, but these findings are not conclusive because of the large variability recorded. The average LC50's were 0.2076+/-0.0164 mg l(-1) (at 20 degrees C) and 0.1544+/-0.0175 mg l(-1) (at 25 degrees C). The reproducers' culture temperature had no effect on neonates' sensitivity to chromium, in spite of performing the tests at temperatures either lower or higher than those at which the neonates had been obtained. The length of neonates produced during the first two clutches (&lt;1.25 mm) was significantly lower than that measured in neonates of following reproductions (&gt;1.3 mm), and were smaller at 25 degrees C; however, this did not seem to affect their sensitivity to chromium.","Effect of culture conditions and mother's age on the sensitivity of Daphnia magna Straus 1820 (Cladocera) neonates to hexavalent chromium Abs: Daphnia magna is a freshwater cladoceran used worldwide as test organism in aquatic toxicity assays. In Mexico there is a test protocol for this species; nevertheless, some aspects of the controlled neonate production, as well as the possible consequences of the reproducers' culture conditions on the response of neonates to the toxic substance, are not completely known. In the present study, we evaluated the effect of temperature and photoperiod on the acute toxicity of CrVI in D. magna neonates, aimed at providing useful information on the Median Lethal Concentration (LC50) to this heavy metal, which is used as reference toxicant in some laboratories. D. magna was cultured at 20 and 25 degrees C, in combination with two photoperiod values: 16:8 and 12:12 (light:dark) during 40 days; the green microalga Ankistrodesmus falcatus (4x10(5) cells ml(-1)) was supplied as food. Once the reproduction began, the neonates were removed and acute toxicity bioassays at 20 and 25 degrees C were performed, by exposing them to hexavalent chromium. We also determined changes in neonates' size at 20 and 25 degrees C. Chromium toxicity increased along with increasing temperatures, and LC50 values were slightly lower for the first and last clutches in the observed period, but these findings are not conclusive because of the large variability recorded. The average LC50's were 0.2076+/-0.0164 mg l(-1) (at 20 degrees C) and 0.1544+/-0.0175 mg l(-1) (at 25 degrees C). The reproducers' culture temperature had no effect on neonates' sensitivity to chromium, in spite of performing the tests at temperatures either lower or higher than those at which the neonates had been obtained. The length of neonates produced during the first two clutches (&lt;1.25 mm) was significantly lower than that measured in neonates of following reproductions (&gt;1.3 mm), and were smaller at 25 degrees C; however, this did not seem to affect their sensitivity to chromium."
1233702,Chen et al. 2006,Application of a by-product of Lentinus edodes to the bioremediation of chromate contaminated water,"The agricultural by-product of Lentinus edodes was used as a novel biosorbent for bioremediation of chromate contaminated waste water in the simulated experimental conditions. The contact time, particle size, biosorbent dosage and optimum pH range were investigated to optimize the sorption condition. The biosorption by the biomass was strongly affected by pH. At pH 1.0-2.5, all hexavalent chromium was diminished, either removed by the biosorbent or reduced to less toxic trivalent chromium even in very high concentration of 1000 mg/L. The adsorbed hexavalent chromium and reduced trivalent chromium were both linearly dependent on the initial chromium concentration. Most uptake of Cr occurred at pH around 4. The maximum uptake of chromium was 21.5 mg/g when simulated with Langmuir model, which showed the potential biosorption capacity of this biomaterial. The change of oxidation-reduction potential (ORP) during biosorption process revealed strong reduction ability of this biosorbent. Comparing analysis from Fourier transform infrared spectrums indicated that nitrogen oxide and carboxyl groups were increased after biosorption. The energy-dispersive X-ray microanalyzer revealed the mechanism of cation exchange during biosorption.","Application of a by-product of Lentinus edodes to the bioremediation of chromate contaminated water Abs: The agricultural by-product of Lentinus edodes was used as a novel biosorbent for bioremediation of chromate contaminated waste water in the simulated experimental conditions. The contact time, particle size, biosorbent dosage and optimum pH range were investigated to optimize the sorption condition. The biosorption by the biomass was strongly affected by pH. At pH 1.0-2.5, all hexavalent chromium was diminished, either removed by the biosorbent or reduced to less toxic trivalent chromium even in very high concentration of 1000 mg/L. The adsorbed hexavalent chromium and reduced trivalent chromium were both linearly dependent on the initial chromium concentration. Most uptake of Cr occurred at pH around 4. The maximum uptake of chromium was 21.5 mg/g when simulated with Langmuir model, which showed the potential biosorption capacity of this biomaterial. The change of oxidation-reduction potential (ORP) during biosorption process revealed strong reduction ability of this biosorbent. Comparing analysis from Fourier transform infrared spectrums indicated that nitrogen oxide and carboxyl groups were increased after biosorption. The energy-dispersive X-ray microanalyzer revealed the mechanism of cation exchange during biosorption."
1233701,Ali Khan and  Ahmad 2006,Detoxification and bioremediation potential of a Pseudomonas fluorescens isolate against the major Indian water pollutants,"A Pseudomonas fluorescens strain was isolated from the soil of industrial estate of Aligarh, India. This strain was resistant to some of the major Indian water pollutants, namely Cd2+, Cr6+, Cu2+, Ni2+, Pb2+, BHC, 2,4-D, mancozeb and phenols up to the levels occurring in the highly polluted regions. Moreover, the test strain seems to have a great potential for the detoxification of these pollutants. The decrease in toxicity as determined by the Allium cepa test was recorded as 62.5% for the model water containing the mixture of test heavy metals, 71.9% for the pesticides, 73.2% for phenols, and 58.5% for combination of all these toxicants. These values were obtained after 24 hours, exposure to the immobilized cells of the test isolate in the calcium alginate matrix at the concentrations of these polutants supposedly present in the highly polluted water systems in India. The efficiency of bioremediation for certain heavy metals at the same concentrations by means of immobilized cells of the test Pseudomonas fluorescens isolate was estimated to be 75.9% for cadmium, 74.2% for hexavalent chromium and 61.0% for lead during the 24 hours' treatment. In view of the preliminary work, the test isolate seems to be a good candidate for the bioremediation of water pollutants.","Detoxification and bioremediation potential of a Pseudomonas fluorescens isolate against the major Indian water pollutants Abs: A Pseudomonas fluorescens strain was isolated from the soil of industrial estate of Aligarh, India. This strain was resistant to some of the major Indian water pollutants, namely Cd2+, Cr6+, Cu2+, Ni2+, Pb2+, BHC, 2,4-D, mancozeb and phenols up to the levels occurring in the highly polluted regions. Moreover, the test strain seems to have a great potential for the detoxification of these pollutants. The decrease in toxicity as determined by the Allium cepa test was recorded as 62.5% for the model water containing the mixture of test heavy metals, 71.9% for the pesticides, 73.2% for phenols, and 58.5% for combination of all these toxicants. These values were obtained after 24 hours, exposure to the immobilized cells of the test isolate in the calcium alginate matrix at the concentrations of these polutants supposedly present in the highly polluted water systems in India. The efficiency of bioremediation for certain heavy metals at the same concentrations by means of immobilized cells of the test Pseudomonas fluorescens isolate was estimated to be 75.9% for cadmium, 74.2% for hexavalent chromium and 61.0% for lead during the 24 hours' treatment. In view of the preliminary work, the test isolate seems to be a good candidate for the bioremediation of water pollutants."
1233699,Mandiwana et al. 2006,Electrothermal atomic absorption spectrometric determination of total and hexavalent chromium in atmospheric aerosols,"A method was developed which allow separate determination of Cr(VI) and total Cr from the same minute sample of atmospheric aerosols. Cr(VI) was leached was with 0.1M Na(2)CO(3) and the total Cr concentrations were determined after acid digestion. The method was validated by the analysis of certified reference materials, CRM 545, Mess-3 and Pacs-2 with good agreement between certified and found values. Cr concentrations in air samples taken around the chromium smelter show concentrations that exceed the maximum allowed levels in 8h with higher values closer to the smelter. The limit of detection (LOD) of the method for Cr(VI) determination in air samples was found to be 0.2 ng m(-3), i.e. lower than offered by the commonly preferred spectrophotometric and colorimetric techniques.","Electrothermal atomic absorption spectrometric determination of total and hexavalent chromium in atmospheric aerosols Abs: A method was developed which allow separate determination of Cr(VI) and total Cr from the same minute sample of atmospheric aerosols. Cr(VI) was leached was with 0.1M Na(2)CO(3) and the total Cr concentrations were determined after acid digestion. The method was validated by the analysis of certified reference materials, CRM 545, Mess-3 and Pacs-2 with good agreement between certified and found values. Cr concentrations in air samples taken around the chromium smelter show concentrations that exceed the maximum allowed levels in 8h with higher values closer to the smelter. The limit of detection (LOD) of the method for Cr(VI) determination in air samples was found to be 0.2 ng m(-3), i.e. lower than offered by the commonly preferred spectrophotometric and colorimetric techniques."
1233698,Rogers et al. 2006,Improving environmental risk management through historical impact assessments,"A historical contaminant impact assessment was conducted at 48 heavy manufacturing facilities located in 20 different states for a U.S.-based company. The facilities evaluated were industrial manufacturing sites that operated for as long as 100 yr and used several types of hazardous substances, including solvents and degreasers, oils and other petroleum products, paints and pigments, and heavy metals. The purpose of conducting the impact assessment was to provide direction and guidance on future environmental objectives and pollution prevention initiatives. The impact assessment involved examining historical investigative and remediation costs since 1985, types of contaminants, subsurface geology, hydrology, and regulatory requirements. The results reveled that 85% of the historical environmental costs were associated with hexavalent chromium and chlorinated solvents. Other contaminants, such as oils and other petroleum products and other heavy metals, were far more commonly detected but only accounted for the remaining 15% of costs. The results also indicated that the costs are also strongly associated with the type of geologic environment to which the chemicals were released. As a result of these findings, an aggressive pollution prevention program has been initiated to eliminate the use of those contaminants that are especially expensive to remediate and to develop stronger and more effective engineering controls at facilities located in sensitive ecological areas.","Improving environmental risk management through historical impact assessments Abs: A historical contaminant impact assessment was conducted at 48 heavy manufacturing facilities located in 20 different states for a U.S.-based company. The facilities evaluated were industrial manufacturing sites that operated for as long as 100 yr and used several types of hazardous substances, including solvents and degreasers, oils and other petroleum products, paints and pigments, and heavy metals. The purpose of conducting the impact assessment was to provide direction and guidance on future environmental objectives and pollution prevention initiatives. The impact assessment involved examining historical investigative and remediation costs since 1985, types of contaminants, subsurface geology, hydrology, and regulatory requirements. The results reveled that 85% of the historical environmental costs were associated with hexavalent chromium and chlorinated solvents. Other contaminants, such as oils and other petroleum products and other heavy metals, were far more commonly detected but only accounted for the remaining 15% of costs. The results also indicated that the costs are also strongly associated with the type of geologic environment to which the chemicals were released. As a result of these findings, an aggressive pollution prevention program has been initiated to eliminate the use of those contaminants that are especially expensive to remediate and to develop stronger and more effective engineering controls at facilities located in sensitive ecological areas."
1233696,Frazer 2006,Shiny science: a new substitute for hexavalent chromium,,Shiny science: a new substitute for hexavalent chromium Abs: 
1233695,Dermatas et al. 2006,Ettringite-induced heave in chromite ore processing residue (COPR) upon ferrous sulfate treatment,"A pilot-scale treatment study was implemented at a deposition site of chromite ore processing residue (COPR) in New Jersey. Ferrous sulfate heptahydrate (FeSO4 x 7H2O) was employed to reduce hexavalent chromium in two dosages with three types of soil mixing equipment. XANES analyses of treated samples cured for 240 days indicated that all treatment combinations failed to meet the Cr(VI) regulatory limit of 240 mg/kg. More importantly, the discrepancy between XANES and alkaline digestion results renders the latter unreliable for regulatory purposes when applied to ferrous-treated COPR. Regardless of Cr-(VI), the introduction of reductant containing sulfate, mechanical mixing, water, acidity, and the resulting temperature increase in treated COPR promoted dissolution of brownmillerite (Ca2FeAlO5), releasing alumina and alkalinity. The pH increase caused initially precipitated gypsum (CaSO4 x 2H2O) to progressively convert to ettringite (Ca6Al2(SO4)3 x 32H2O) and its associated volume expansion under both in situ and ex situ conditions, with a maximum of 0.8 m vertical swell within 40 days of curing. While Cr-(VI) treatment remains a challenge, the intentional exhaustion of the heave potential of COPR by transforming all Al sources to ettringite emerges as a possible solution to delayed ettringite formation, which would hamper site redevelopment.","Ettringite-induced heave in chromite ore processing residue (COPR) upon ferrous sulfate treatment Abs: A pilot-scale treatment study was implemented at a deposition site of chromite ore processing residue (COPR) in New Jersey. Ferrous sulfate heptahydrate (FeSO4 x 7H2O) was employed to reduce hexavalent chromium in two dosages with three types of soil mixing equipment. XANES analyses of treated samples cured for 240 days indicated that all treatment combinations failed to meet the Cr(VI) regulatory limit of 240 mg/kg. More importantly, the discrepancy between XANES and alkaline digestion results renders the latter unreliable for regulatory purposes when applied to ferrous-treated COPR. Regardless of Cr-(VI), the introduction of reductant containing sulfate, mechanical mixing, water, acidity, and the resulting temperature increase in treated COPR promoted dissolution of brownmillerite (Ca2FeAlO5), releasing alumina and alkalinity. The pH increase caused initially precipitated gypsum (CaSO4 x 2H2O) to progressively convert to ettringite (Ca6Al2(SO4)3 x 32H2O) and its associated volume expansion under both in situ and ex situ conditions, with a maximum of 0.8 m vertical swell within 40 days of curing. While Cr-(VI) treatment remains a challenge, the intentional exhaustion of the heave potential of COPR by transforming all Al sources to ettringite emerges as a possible solution to delayed ettringite formation, which would hamper site redevelopment."
1233694,Post and  Stern 2006,"Comments on article ""Toxicity and carcinogenicity of chromium compounds in humans"" by Costa and Klein","The recent article by Costa and Klein (2006) contains several inaccuracies about the federal drinking water standard for chromium. The federal drinking water standard for chromium is 100 ppb, not 50 ppb as stated by Costa and Klein, and it is based on non-carcinogenic effects, not a one in one million cancer risk level. The question of whether or not hexavalent chromium is carcinogenic via the oral route is the focus of much current interest and has major implications for regulation of chromium in drinking water and soil. The chronic drinking water study of hexavalent chromium currently being conducted by the National Toxicology Program will provide further information that will be useful in addressing this question.","Comments on article ""Toxicity and carcinogenicity of chromium compounds in humans"" by Costa and Klein Abs: The recent article by Costa and Klein (2006) contains several inaccuracies about the federal drinking water standard for chromium. The federal drinking water standard for chromium is 100 ppb, not 50 ppb as stated by Costa and Klein, and it is based on non-carcinogenic effects, not a one in one million cancer risk level. The question of whether or not hexavalent chromium is carcinogenic via the oral route is the focus of much current interest and has major implications for regulation of chromium in drinking water and soil. The chronic drinking water study of hexavalent chromium currently being conducted by the National Toxicology Program will provide further information that will be useful in addressing this question."
1233693,Martin et al. 2006,Ascorbate is a pro-oxidant in chromium-treated human lung cells,"The human A549 lung cell line is used in this study as a model to evaluate chromium toxicity and mutagenesis since inhalation exposure of this metal gives rise to an epidemiology that indicates the lung as a target organ of chromium toxicity. Hexavalent chromium is considered the carcinogenic form of chromium, however it must be reductively activated following uptake into cells in order to react with intracellular constituents. We have previously established that the fluorescent dyes, dichlorofluorescein (DCF) and dihydrorhodamine, are effective indicators of the reductive activation of chromium and are sensitive measures of the formation of highly reactive chromium species (RCS) intracellularly. In order to examine the role of the two common intracellular reductants, glutathione and ascorbic acid (Vitamin C) in generating RCS intracellularly, we manipulated their intracellular levels through the use of buthionine sulfoximine (BSO) or by the addition of ascorbate into the culture media. We found that the high levels of glutathione in this cancer cell line lowered endogenous oxidation levels markedly, and that, by decreasing intracellular glutathione, BSO not only generated a higher background level of endogenous intracellular oxidation but the chromium-stimulated oxidation also increased markedly. Contrary to it appellation as an anti-oxidant, ascorbic acid stimulated a strong pro-oxidant response upon chromium treatment and this pro-oxidant response was evident regardless of the levels of glutathione in the cells. Based on these results, we conclude that ascorbic acid acts as a pro-oxidant in chromium-treated cells.","Ascorbate is a pro-oxidant in chromium-treated human lung cells Abs: The human A549 lung cell line is used in this study as a model to evaluate chromium toxicity and mutagenesis since inhalation exposure of this metal gives rise to an epidemiology that indicates the lung as a target organ of chromium toxicity. Hexavalent chromium is considered the carcinogenic form of chromium, however it must be reductively activated following uptake into cells in order to react with intracellular constituents. We have previously established that the fluorescent dyes, dichlorofluorescein (DCF) and dihydrorhodamine, are effective indicators of the reductive activation of chromium and are sensitive measures of the formation of highly reactive chromium species (RCS) intracellularly. In order to examine the role of the two common intracellular reductants, glutathione and ascorbic acid (Vitamin C) in generating RCS intracellularly, we manipulated their intracellular levels through the use of buthionine sulfoximine (BSO) or by the addition of ascorbate into the culture media. We found that the high levels of glutathione in this cancer cell line lowered endogenous oxidation levels markedly, and that, by decreasing intracellular glutathione, BSO not only generated a higher background level of endogenous intracellular oxidation but the chromium-stimulated oxidation also increased markedly. Contrary to it appellation as an anti-oxidant, ascorbic acid stimulated a strong pro-oxidant response upon chromium treatment and this pro-oxidant response was evident regardless of the levels of glutathione in the cells. Based on these results, we conclude that ascorbic acid acts as a pro-oxidant in chromium-treated cells."
1233692,Roling et al. 2006,Hexavalent chromium reduces larval growth and alters gene expression in mummichog (Fundulus heteroclitus),"Hexavalent chromium [Cr(VI)] is a common bioavailable metal ion that causes oxidative stress, DNA adducts, and perturbs gene expression. Changes in gene expression are useful biomarkers of toxicant exposure that provide information about an organism's health, adaptability, and toxicant-specific effects. Therefore, we developed a cDNA array for the estuarine sentinel species mummichog (Fundulus heteroclitus). Mummichog larvae were exposed to concentrations ranging from 0 to 24 mg/L (462 microM) of Cr(VI) for 30 d, and growth was measured to determine the no-observable-effect concentration (1.5 mg/L) and the lowest-observable-effect concentration (3 mg/L). Body burdens from Cr(VI)-exposed fish showed a dose-dependent increase and were inversely correlated to body weight. Mummichog larvae exposed to Cr(VI) differentially expressed 16 genes in a dose-dependent manner, including GLUT-2, L-FABP, ATPase synthase 8, type II keratin, TBT-binding protein, and complement component C3-2. Many of these genes are involved in energy metabolism or growth, which is consistent with the reduced growth observed. In subsequent experiments, adults were exposed to Cr(VI) for 7 d at 0, 1.5, or 3 mg/L, because adult mummichog are used in monitoring Superfund sites. Hexavalent chromium altered the expression of 10 genes in adult liver, including HGFA, H-FABP, and complement component C3-2. Many of these genes also are involved in energy metabolism. The mummichog arrays provide a potential mechanism for the effects of Cr(VI) on growth. We anticipate using these arrays and the data they provide to monitor effects at polluted sites, to assess the bioavailability of chromium at these sites, and to investigate the efficacy of remediation in chromium-polluted estuaries.","Hexavalent chromium reduces larval growth and alters gene expression in mummichog (Fundulus heteroclitus) Abs: Hexavalent chromium [Cr(VI)] is a common bioavailable metal ion that causes oxidative stress, DNA adducts, and perturbs gene expression. Changes in gene expression are useful biomarkers of toxicant exposure that provide information about an organism's health, adaptability, and toxicant-specific effects. Therefore, we developed a cDNA array for the estuarine sentinel species mummichog (Fundulus heteroclitus). Mummichog larvae were exposed to concentrations ranging from 0 to 24 mg/L (462 microM) of Cr(VI) for 30 d, and growth was measured to determine the no-observable-effect concentration (1.5 mg/L) and the lowest-observable-effect concentration (3 mg/L). Body burdens from Cr(VI)-exposed fish showed a dose-dependent increase and were inversely correlated to body weight. Mummichog larvae exposed to Cr(VI) differentially expressed 16 genes in a dose-dependent manner, including GLUT-2, L-FABP, ATPase synthase 8, type II keratin, TBT-binding protein, and complement component C3-2. Many of these genes are involved in energy metabolism or growth, which is consistent with the reduced growth observed. In subsequent experiments, adults were exposed to Cr(VI) for 7 d at 0, 1.5, or 3 mg/L, because adult mummichog are used in monitoring Superfund sites. Hexavalent chromium altered the expression of 10 genes in adult liver, including HGFA, H-FABP, and complement component C3-2. Many of these genes also are involved in energy metabolism. The mummichog arrays provide a potential mechanism for the effects of Cr(VI) on growth. We anticipate using these arrays and the data they provide to monitor effects at polluted sites, to assess the bioavailability of chromium at these sites, and to investigate the efficacy of remediation in chromium-polluted estuaries."
1233691,Mian 2006,Effects of dairy wastewater on mosquitoes in southern California,"The effect of dairy pond water quality on mosquito biology was studied under laboratory conditions during 2004. Due to high turbidity and larval toxicity of raw water samples from dairy ponds with no mosquito breeding, water samples from both mosquito breeding and non-breeding ponds were filtered and diluted 5X with distilled water prior to being tested for sublethal effects on mosquito development. The diluted pond waters showed no significant deleterious effects on the overall development of Culex quiquefasciatus Say at 23.9 degrees and 26.6 degrees C. However, the 3rd and 4th instar larvae were significantly shorter and lighter in weight when reared in diluted water samples from mosquito non-breeding ponds. Similar effects were found on the developmental stages of Cx. tarsalis Coquillette. Data on water quality parameters of filtered pond waters showed higher levels of hexavalent chromium (4X), nitrites (10X), nitrates (2X), sulfates (5X), and salinity (2X) in water samples from non-breeding ponds. Based on these data, the presence of high levels of hexavalent chromium and sulfate appear to be responsible for the absence of mosquito breeding in some dairy ponds.","Effects of dairy wastewater on mosquitoes in southern California Abs: The effect of dairy pond water quality on mosquito biology was studied under laboratory conditions during 2004. Due to high turbidity and larval toxicity of raw water samples from dairy ponds with no mosquito breeding, water samples from both mosquito breeding and non-breeding ponds were filtered and diluted 5X with distilled water prior to being tested for sublethal effects on mosquito development. The diluted pond waters showed no significant deleterious effects on the overall development of Culex quiquefasciatus Say at 23.9 degrees and 26.6 degrees C. However, the 3rd and 4th instar larvae were significantly shorter and lighter in weight when reared in diluted water samples from mosquito non-breeding ponds. Similar effects were found on the developmental stages of Cx. tarsalis Coquillette. Data on water quality parameters of filtered pond waters showed higher levels of hexavalent chromium (4X), nitrites (10X), nitrates (2X), sulfates (5X), and salinity (2X) in water samples from non-breeding ponds. Based on these data, the presence of high levels of hexavalent chromium and sulfate appear to be responsible for the absence of mosquito breeding in some dairy ponds."
1233690,Speranza et al. 2007,Both trivalent and hexavalent chromium strongly alter in vitro germination and ultrastructure of kiwifruit pollen,"Due to its widespread industrial use, chromium is considered a dangerous environmental pollutant. It is known to inhibit plant growth and development. The present study provides the first evidence of the toxicity of this metal on the male haploid generation of a higher plant. Both Cr(III) and Cr(VI) species, supplied as CrCl(3) and CrO(3), respectively, exerted a strong dose-dependent inhibitory effect on kiwifruit pollen tube emergence and growth. Cr(III) resulted more effective than Cr(VI) in the 16-75microM interval; moreover, complete inhibition of germination was attained at much lower doses than Cr(VI). Also tube morphology was affected. While the plasma membrane was still undamaged in the large majority of the treated pollen grains, dramatic ultrastructural alterations were induced by chromium including chromatin condensation, swelling of mitochondria, cytoplasmic vacuolization, and perturbed arrangement of endoplasmic reticulum cisternae. Thus, it seems that the impact of the two chromium species on kiwifruit pollen may result in severe compromission of both essential structures and functions of the male gametophyte.","Both trivalent and hexavalent chromium strongly alter in vitro germination and ultrastructure of kiwifruit pollen Abs: Due to its widespread industrial use, chromium is considered a dangerous environmental pollutant. It is known to inhibit plant growth and development. The present study provides the first evidence of the toxicity of this metal on the male haploid generation of a higher plant. Both Cr(III) and Cr(VI) species, supplied as CrCl(3) and CrO(3), respectively, exerted a strong dose-dependent inhibitory effect on kiwifruit pollen tube emergence and growth. Cr(III) resulted more effective than Cr(VI) in the 16-75microM interval; moreover, complete inhibition of germination was attained at much lower doses than Cr(VI). Also tube morphology was affected. While the plasma membrane was still undamaged in the large majority of the treated pollen grains, dramatic ultrastructural alterations were induced by chromium including chromatin condensation, swelling of mitochondria, cytoplasmic vacuolization, and perturbed arrangement of endoplasmic reticulum cisternae. Thus, it seems that the impact of the two chromium species on kiwifruit pollen may result in severe compromission of both essential structures and functions of the male gametophyte."
1233688,Chrysochoou and  Dermatas 2007,Application of the Rietveld method to assess chromium(VI) speciation in chromite ore processing residue,"The Rietveld method allows the quantification of crystalline phases and amorphous material identified by X-ray powder diffraction (XRPD) and other diffraction methods. The method assists in determining the speciation of contaminants in solid matrices both qualitatively and quantitatively in a statistically defensible approach, as it does not focus on a microscale. Rietveld was applied to chromite ore processing residue (COPR), a cementitious waste containing hexavalent chromium. Calcium aluminum chromium oxide hydrates (CACs) were the crystalline phases identified by XRPD that bind Cr(6+) in COPR according to their chemical formula. Rietveld quantification, combined with mass balances on Cr(6+), showed that CACs may bind Cr(6+) in variable percentages, ranging from 25% to 85%. Analysis of duplicate samples showed that material variability is the predominant factor of uncertainty in evaluating the role of CACs in Cr(6+) speciation, provided that a consistent quantification strategy is pursued. The choice of strategy was performed on the basis of the pertinent literature, preliminary analyses of the equipment and the software settings, and mass balances. The correlation between the average CAC-bound Cr(6+) concentration and the total Cr(6+) for five samples (R(2)=0.94), extracted from different zones and soil borings, suggests that CACs are a primary sink for Cr(6+) in COPR.","Application of the Rietveld method to assess chromium(VI) speciation in chromite ore processing residue Abs: The Rietveld method allows the quantification of crystalline phases and amorphous material identified by X-ray powder diffraction (XRPD) and other diffraction methods. The method assists in determining the speciation of contaminants in solid matrices both qualitatively and quantitatively in a statistically defensible approach, as it does not focus on a microscale. Rietveld was applied to chromite ore processing residue (COPR), a cementitious waste containing hexavalent chromium. Calcium aluminum chromium oxide hydrates (CACs) were the crystalline phases identified by XRPD that bind Cr(6+) in COPR according to their chemical formula. Rietveld quantification, combined with mass balances on Cr(6+), showed that CACs may bind Cr(6+) in variable percentages, ranging from 25% to 85%. Analysis of duplicate samples showed that material variability is the predominant factor of uncertainty in evaluating the role of CACs in Cr(6+) speciation, provided that a consistent quantification strategy is pursued. The choice of strategy was performed on the basis of the pertinent literature, preliminary analyses of the equipment and the software settings, and mass balances. The correlation between the average CAC-bound Cr(6+) concentration and the total Cr(6+) for five samples (R(2)=0.94), extracted from different zones and soil borings, suggests that CACs are a primary sink for Cr(6+) in COPR."
1233687,Manning et al. 2007,Spectroscopic investigation of Cr(III)- and Cr(VI)-treated nanoscale zerovalent iron,"The reaction of hexavalent chromium (Cr(VI)) with zerovalent iron (Fe0) during soil and groundwater remediation is an important environmental process. This study used several techniques including X-ray photoelectron spectroscopy (XPS) and X-ray absorption spectroscopy to investigate nanometer scale Fe0 particles (nano Fe0) treated with Cr(III) and Cr(VI). X-ray diffraction and XPS analyses of oxidized nano Fe0 showed the crystalline Fe(III) phase is composed of lepidocrocite (gamma-FeOOH). Results of XPS Cr 2p data and Cr K-edge X-ray absorption near edge spectroscopy (XANES) provided evidence that Cr(VI) was entirely reduced to Cr(III) by nano Fe0 with no residual Cr(VI) after reaction. In addition, XPS and XANES results of Cr(III) precipitated as Cr(OH)3 in the presence of corroding nano Fe0 were nearly identical to the Cr(VI)-nano Fe0 reaction product. Detailed analysis of XPS O 1s line spectra revealed that both Cr(III)- and Cr(VI)-treated nano Fe0 yielded a predominantly hydroxylated Cr(OH)3 and/ or a mixed phase CrxFe(1 - x)(OH)3 product. The structure of the Cr(III)- and Cr(VI)-treated nano Fe0 determined using extended X-ray absorption fine structure spectroscopy (EXAFS) revealed octahedral Cr(III) with Cr-O interatomic distances between 1.97 and 1.98 A for both Cr(III) and Cr(VI) treatments and a pronounced Cr-Cr second interatomic shell at 3.01 A. Our results suggest that the reaction product of Cr(VI)-treated nano Fe0 is either a poorly ordered Cr(OH)3 precipitate or possibly a mixed phase CrxFe(1 - x)(OH)3 product, both of which are highly insoluble under environmental conditions.","Spectroscopic investigation of Cr(III)- and Cr(VI)-treated nanoscale zerovalent iron Abs: The reaction of hexavalent chromium (Cr(VI)) with zerovalent iron (Fe0) during soil and groundwater remediation is an important environmental process. This study used several techniques including X-ray photoelectron spectroscopy (XPS) and X-ray absorption spectroscopy to investigate nanometer scale Fe0 particles (nano Fe0) treated with Cr(III) and Cr(VI). X-ray diffraction and XPS analyses of oxidized nano Fe0 showed the crystalline Fe(III) phase is composed of lepidocrocite (gamma-FeOOH). Results of XPS Cr 2p data and Cr K-edge X-ray absorption near edge spectroscopy (XANES) provided evidence that Cr(VI) was entirely reduced to Cr(III) by nano Fe0 with no residual Cr(VI) after reaction. In addition, XPS and XANES results of Cr(III) precipitated as Cr(OH)3 in the presence of corroding nano Fe0 were nearly identical to the Cr(VI)-nano Fe0 reaction product. Detailed analysis of XPS O 1s line spectra revealed that both Cr(III)- and Cr(VI)-treated nano Fe0 yielded a predominantly hydroxylated Cr(OH)3 and/ or a mixed phase CrxFe(1 - x)(OH)3 product. The structure of the Cr(III)- and Cr(VI)-treated nano Fe0 determined using extended X-ray absorption fine structure spectroscopy (EXAFS) revealed octahedral Cr(III) with Cr-O interatomic distances between 1.97 and 1.98 A for both Cr(III) and Cr(VI) treatments and a pronounced Cr-Cr second interatomic shell at 3.01 A. Our results suggest that the reaction product of Cr(VI)-treated nano Fe0 is either a poorly ordered Cr(OH)3 precipitate or possibly a mixed phase CrxFe(1 - x)(OH)3 product, both of which are highly insoluble under environmental conditions."
1233684,Hillier et al. 2007,Hydrogarnet: a host phase for Cr(VI) in chromite ore processing residue (COPR) and other high pH wastes,"For understanding both the environmental behavior and developing remediation treatments for chromium ore processing residue (COPR) it is important to identify all the potentially soluble sources of Cr(VI). Hydrogarnet has been identified as a major phase in COPR and it has been previously speculated that it has a capacity to host Cr(VI). Here we provide direct evidence of this capacity by demonstrating the incorporation of Cr(VI) into laboratory synthesized hydrogarnet. Electron microscopy and energy dispersive X-ray microanalysis show incorporation of approximately 17000-22000 mg Cr(VI) kg(-1) hydrogarnet. X-ray powder diffraction data show that peak intensities are altered by chromium substitution and that chromium substituted hydrogarnets have a smaller unit cell than the pure Ca-Al end member. This is consistent with substitution of hydroxyl tetrahedra by smaller chromate tetrahedra. Electron energy loss spectroscopy confirms the tetrahedral coordination and hexavalent oxidation state of chromium in the hydrogarnets. The maximum amount of hexavalent chromium that can be introduced synthetically corresponds to a replacement of about one out of every eight hydroxyl tetrahedral per unit cell by a CrO4(2-) tetrahedra and tallies closely with the amount of chromium measured in hydrogarnets from COPR. Chromium-bearing hydrogarnet is the most abundant crystalline phase in millions of tons of COPR contaminating land around Glasgow, Scotland, and was recently identified in COPR from sites in North America. Calculations based on its abundance and its Cr(VI) content indicate that hydrogarnet can host as much as 50% of the Cr(VI) found in some COPR samples.","Hydrogarnet: a host phase for Cr(VI) in chromite ore processing residue (COPR) and other high pH wastes Abs: For understanding both the environmental behavior and developing remediation treatments for chromium ore processing residue (COPR) it is important to identify all the potentially soluble sources of Cr(VI). Hydrogarnet has been identified as a major phase in COPR and it has been previously speculated that it has a capacity to host Cr(VI). Here we provide direct evidence of this capacity by demonstrating the incorporation of Cr(VI) into laboratory synthesized hydrogarnet. Electron microscopy and energy dispersive X-ray microanalysis show incorporation of approximately 17000-22000 mg Cr(VI) kg(-1) hydrogarnet. X-ray powder diffraction data show that peak intensities are altered by chromium substitution and that chromium substituted hydrogarnets have a smaller unit cell than the pure Ca-Al end member. This is consistent with substitution of hydroxyl tetrahedra by smaller chromate tetrahedra. Electron energy loss spectroscopy confirms the tetrahedral coordination and hexavalent oxidation state of chromium in the hydrogarnets. The maximum amount of hexavalent chromium that can be introduced synthetically corresponds to a replacement of about one out of every eight hydroxyl tetrahedral per unit cell by a CrO4(2-) tetrahedra and tallies closely with the amount of chromium measured in hydrogarnets from COPR. Chromium-bearing hydrogarnet is the most abundant crystalline phase in millions of tons of COPR contaminating land around Glasgow, Scotland, and was recently identified in COPR from sites in North America. Calculations based on its abundance and its Cr(VI) content indicate that hydrogarnet can host as much as 50% of the Cr(VI) found in some COPR samples."
1233683,Venditti et al. 2007,Removal of chromate from water by a new CTAB-silica gelatin composite,"A novel composite able to remove hexavalent chromium Cr(VI) from aqueous solutions was obtained by adding the silica precursor tetraethoxysilane (TEOS) to the hexadecyltrimethylammonium bromide (CTAB) microemulsion-based gel. A physical characterization of the new matrix revealed high stability of the silica gelatin composite in water at high temperatures and at neutral pH. Good efficiency in removing chromate from neutral solutions was also demonstrated by the adsorption kinetics. In particular, the adsorption data of chromate obtained with the CTAB-silica gelatin composite at 25 degrees C and pH 7.5 are described by the Freundlich isotherm model. The specific role of CTAB in the silica gelatin composite was also evaluated by comparing the kinetics of the anionic AOT-silica gelatin composite to the CTAB one. The data collected clearly showed that the positively charged surfactant was necessary to efficiently adsorb Cr(VI) from aqueous solutions. SEM and pulsed gradient spin-echo NMR analysis of the composite demonstrated that the silicon is well assembled in the gelatin network, in which water molecules maintain a high mobility. The diffusion coefficient of water in this system was shown to remain close to the value of pure water. Finally, X-ray analyses of the elemental content in the CTAB-silica gelatin composite indicated no difference in terms of percentage of silica distributions in different areas of the matrix and suggested that chromium adsorption could take place in internal areas.","Removal of chromate from water by a new CTAB-silica gelatin composite Abs: A novel composite able to remove hexavalent chromium Cr(VI) from aqueous solutions was obtained by adding the silica precursor tetraethoxysilane (TEOS) to the hexadecyltrimethylammonium bromide (CTAB) microemulsion-based gel. A physical characterization of the new matrix revealed high stability of the silica gelatin composite in water at high temperatures and at neutral pH. Good efficiency in removing chromate from neutral solutions was also demonstrated by the adsorption kinetics. In particular, the adsorption data of chromate obtained with the CTAB-silica gelatin composite at 25 degrees C and pH 7.5 are described by the Freundlich isotherm model. The specific role of CTAB in the silica gelatin composite was also evaluated by comparing the kinetics of the anionic AOT-silica gelatin composite to the CTAB one. The data collected clearly showed that the positively charged surfactant was necessary to efficiently adsorb Cr(VI) from aqueous solutions. SEM and pulsed gradient spin-echo NMR analysis of the composite demonstrated that the silicon is well assembled in the gelatin network, in which water molecules maintain a high mobility. The diffusion coefficient of water in this system was shown to remain close to the value of pure water. Finally, X-ray analyses of the elemental content in the CTAB-silica gelatin composite indicated no difference in terms of percentage of silica distributions in different areas of the matrix and suggested that chromium adsorption could take place in internal areas."
1233682,Curtis et al. 2007,"The effects of nickel and chromium on human keratinocytes: differences in viability, cell associated metal and IL-1alpha release","This study was carried out to assess the effects of chromium and nickel upon isolated keratinocytes as an in vitro model of human skin. Keratinocytes were isolated from healthy volunteer skin samples of unknown metal sensitivity (n=10) and were compared with cells from patient biopsies of known metal sensitivity (n=7). Cells were dosed with a concentration range of nickel and chromium (0-10,000 microM) and cellular mitochondrial activity, viability, metal uptake and cytokine release were measured. Responses of primary versus passaged keratinocytes were also compared. Toxicity data from primary and passaged keratinocytes was statistically analysed by the non-linear Hill Plot model. Results showed that hexavalent chromium was significantly more cytotoxic, associated more with keratinocytes and induced a dose dependant release of IL-1alpha compared to nickel. Significant differences were observed between primary and passaged keratinocytes with regard to the toxicity of chromium and nickel and variation of response. No differences were observed in the cytotoxicity or cytokine release induced by chromium or nickel for the known sensitised biopsy patient samples (n=4) compared to patch test negative controls (n=3). The results from this study suggest human keratinocytes in vitro respond very differently to chromium and nickel.","The effects of nickel and chromium on human keratinocytes: differences in viability, cell associated metal and IL-1alpha release Abs: This study was carried out to assess the effects of chromium and nickel upon isolated keratinocytes as an in vitro model of human skin. Keratinocytes were isolated from healthy volunteer skin samples of unknown metal sensitivity (n=10) and were compared with cells from patient biopsies of known metal sensitivity (n=7). Cells were dosed with a concentration range of nickel and chromium (0-10,000 microM) and cellular mitochondrial activity, viability, metal uptake and cytokine release were measured. Responses of primary versus passaged keratinocytes were also compared. Toxicity data from primary and passaged keratinocytes was statistically analysed by the non-linear Hill Plot model. Results showed that hexavalent chromium was significantly more cytotoxic, associated more with keratinocytes and induced a dose dependant release of IL-1alpha compared to nickel. Significant differences were observed between primary and passaged keratinocytes with regard to the toxicity of chromium and nickel and variation of response. No differences were observed in the cytotoxicity or cytokine release induced by chromium or nickel for the known sensitised biopsy patient samples (n=4) compared to patch test negative controls (n=3). The results from this study suggest human keratinocytes in vitro respond very differently to chromium and nickel."
1233680,Dubey and  Gopal 2007,Adsorption of chromium(VI) on low cost adsorbents derived from agricultural waste material: a comparative study,"Two low cost adsorbents were prepared by using groundnut husk and were tested for the removal of chromium. All the experiments were carried out in batch process with chromium spiked samples of drinking water. Silver impregnated groundnut husk carbon and groundnut husk carbon were tested for the removal of chromium(VI). Effects of adsorbent quantity, pH, contact time and agitation rate were investigated on removal of chromium. The adsorption data were fitted well by Freundlich adsorption isotherm. Approximately, 97% of hexavalent chromium was removed at pH 3 within 5h. It was found that adsorbents chemically modified with an oxidizing agent demonstrated better chromium removal capabilities as compared to pure adsorbents in terms of their adsorption rate. On the basis of present studies, it can be concluded that groundnut husk carbon oxidized with silver treatment, has a higher chromium adsorption capacities.","Adsorption of chromium(VI) on low cost adsorbents derived from agricultural waste material: a comparative study Abs: Two low cost adsorbents were prepared by using groundnut husk and were tested for the removal of chromium. All the experiments were carried out in batch process with chromium spiked samples of drinking water. Silver impregnated groundnut husk carbon and groundnut husk carbon were tested for the removal of chromium(VI). Effects of adsorbent quantity, pH, contact time and agitation rate were investigated on removal of chromium. The adsorption data were fitted well by Freundlich adsorption isotherm. Approximately, 97% of hexavalent chromium was removed at pH 3 within 5h. It was found that adsorbents chemically modified with an oxidizing agent demonstrated better chromium removal capabilities as compared to pure adsorbents in terms of their adsorption rate. On the basis of present studies, it can be concluded that groundnut husk carbon oxidized with silver treatment, has a higher chromium adsorption capacities."
1233679,Martello et al. 2007,"Chromium geochemistry and bioaccumulation in sediments from the lower Hackensack River, New Jersey","Total and hexavalent chromium [Cr(VI)] were measured in sediment and sediment porewater in the lower Hackensack River (NJ) to assess the relationship between sediment geochemistry and chromium speciation, which in turn controls the mobility, bioavailability, and toxicity of chromium. Between 2003 and 2005, &gt;100 surface (0 to 15 cm) sediment samples were tested for total chromium and Cr(VI), acid-volatile sulfides (AVS), ferrous iron (Fe(II)), divalent manganese (Mn(II)), ammonia, and organic carbon. Sediment porewater samples were collected by centrifugation or using in situ samplers colocated with the collection of sediments. In whole sediments, total chromium and Cr(VI) concentrations ranged from 5 to 9190 mg/kg dry weight (dw) and from &lt;0.47 to 31 mg/kg dw, respectively. Sediment porewater concentrations ranged from &lt;10 to 83 microg/l for total chromium; Cr(VI) was not detected in sediment porewater (n = 78). Concentrations of AVS (ranging between &lt;10.6 to 4178 mg/kg) and other geochemistry measurements indicated anoxic, reducing conditions in the majority of sediment samples. In polychaetes (Nereis virens) and clams (Macoma nasuta) exposed in the laboratory for 28 days to sediments contained between 135 and 1780 mg/kg dw total chromium, concentrations in whole tissues after 24-hour depuration ranged between 1.2 and 14.8 mg/kg wet weight (ww; median 1.6 mg/kg ww) total chromium. In whole tissues of indigenous polychaetes collected from the sediment, tissue concentrations of total chromium ranged between 1.0 and 37.5 mg/kg ww (median = 2.1 mg/kg ww). Chromium concentrations in whole tissues of animals exposed in the field or in the laboratory showed no relationship with total chromium or Cr(VI) concentrations in the sediment. There were no statistical differences among animals exposed to sediments from site and reference locations. The results of this study are consistent with sediment studies conducted elsewhere indicating low chromium bioavailability in sediment under reducing conditions. This study also highlights the importance of sediment geochemistry and in situ porewater measurements to understand the ecological significance of chromium in sediment and the potential for human health and ecological exposures.","Chromium geochemistry and bioaccumulation in sediments from the lower Hackensack River, New Jersey Abs: Total and hexavalent chromium [Cr(VI)] were measured in sediment and sediment porewater in the lower Hackensack River (NJ) to assess the relationship between sediment geochemistry and chromium speciation, which in turn controls the mobility, bioavailability, and toxicity of chromium. Between 2003 and 2005, &gt;100 surface (0 to 15 cm) sediment samples were tested for total chromium and Cr(VI), acid-volatile sulfides (AVS), ferrous iron (Fe(II)), divalent manganese (Mn(II)), ammonia, and organic carbon. Sediment porewater samples were collected by centrifugation or using in situ samplers colocated with the collection of sediments. In whole sediments, total chromium and Cr(VI) concentrations ranged from 5 to 9190 mg/kg dry weight (dw) and from &lt;0.47 to 31 mg/kg dw, respectively. Sediment porewater concentrations ranged from &lt;10 to 83 microg/l for total chromium; Cr(VI) was not detected in sediment porewater (n = 78). Concentrations of AVS (ranging between &lt;10.6 to 4178 mg/kg) and other geochemistry measurements indicated anoxic, reducing conditions in the majority of sediment samples. In polychaetes (Nereis virens) and clams (Macoma nasuta) exposed in the laboratory for 28 days to sediments contained between 135 and 1780 mg/kg dw total chromium, concentrations in whole tissues after 24-hour depuration ranged between 1.2 and 14.8 mg/kg wet weight (ww; median 1.6 mg/kg ww) total chromium. In whole tissues of indigenous polychaetes collected from the sediment, tissue concentrations of total chromium ranged between 1.0 and 37.5 mg/kg ww (median = 2.1 mg/kg ww). Chromium concentrations in whole tissues of animals exposed in the field or in the laboratory showed no relationship with total chromium or Cr(VI) concentrations in the sediment. There were no statistical differences among animals exposed to sediments from site and reference locations. The results of this study are consistent with sediment studies conducted elsewhere indicating low chromium bioavailability in sediment under reducing conditions. This study also highlights the importance of sediment geochemistry and in situ porewater measurements to understand the ecological significance of chromium in sediment and the potential for human health and ecological exposures."
1233678,Das and  Guha 2007,Biosorption of chromium by Termitomyces clypeatus,"The manuscript describes removal of chromium from aqueous solution by biomass of different moulds and yeasts. The biomass of Termitomyces clypeatus (TCB) is found to be the most effective of all the fungal species tested. The sorption of hexavalent chromium by live TCB depends on the pH of the solution, the optimum pH value being 3.0. The process follows Langmuir isotherm (regression coefficient 0.998, chi(2)-square 5.03) model with uniform distribution over the surface which gets strong support from the X-ray elemental mapping of chromium adsorbed biomass. The amino, carboxyl, hydroxyl, and phosphate groups of the biomass are involved in chemical interaction with the chromate ion forming a cage like structure depicted by scanning electron microscopic (SEM) and Fourier transform infrared spectroscopic (FTIR) results. Desorption and FTIR studies also exhibited that Cr(6+) is reduced to trivalent chromium on binding to the cell surface. The level of chromium concentration present in the effluent of tannery industries' is reduced to a permissible limit using TCB as adsorbent.","Biosorption of chromium by Termitomyces clypeatus Abs: The manuscript describes removal of chromium from aqueous solution by biomass of different moulds and yeasts. The biomass of Termitomyces clypeatus (TCB) is found to be the most effective of all the fungal species tested. The sorption of hexavalent chromium by live TCB depends on the pH of the solution, the optimum pH value being 3.0. The process follows Langmuir isotherm (regression coefficient 0.998, chi(2)-square 5.03) model with uniform distribution over the surface which gets strong support from the X-ray elemental mapping of chromium adsorbed biomass. The amino, carboxyl, hydroxyl, and phosphate groups of the biomass are involved in chemical interaction with the chromate ion forming a cage like structure depicted by scanning electron microscopic (SEM) and Fourier transform infrared spectroscopic (FTIR) results. Desorption and FTIR studies also exhibited that Cr(6+) is reduced to trivalent chromium on binding to the cell surface. The level of chromium concentration present in the effluent of tannery industries' is reduced to a permissible limit using TCB as adsorbent."
1233677,Srivastava and  Thakur 2007,Evaluation of biosorption potency of Acinetobacter sp. for removal of hexavalent chromium from tannery effluent,"Two bacterial consortia were developed by continuous enrichment of microbial population of tannery and pulp and paper mill effluent contained Serratia mercascens, Pseudomonas fluorescence, Escherichia coli, Pseudomonas aeruginosa and Acinetobacter sp. identified by 16S rDNA method. The consortia evaluated for removal of chromate [(Cr(VI)] in shake flask culture indicated pulp and paper mill consortium had more potential for removal of chromate. Acinetobacter sp. isolated from pulp and paper mill consortium removed higher amount of chromate [Cr(VI)] under aerobic conditions. Parameters optimized in different carbon, nitrogen sources, and pH, indicated maximum removal of chromate in sodium acetate (0.2%), sodium nitrate (0.1%) and pH 7 by Acinetobacter sp. Bacteria was applied in 2-l bioreactor significantly removed chromate after 3 days. The results of the study indicated removal of more than 75% chromium by Acinetobacter sp. determined by diphenylcarbazide colorimetric assay and atomic absorption spectrophotometer after 7 days. Study of microbial [Cr(VI)] removal and identification of reduction intermediates has been hindered by the lack of analytical techniques. Therefore, removal of chromium was further substantiated by transmission electron microscopy (TEM), scanning electron microscopy (SEM) and energy-dispersive X-ray spectroscopy (EDX) which indicated bioaccumulation of chromium in the bacterial cells.","Evaluation of biosorption potency of Acinetobacter sp. for removal of hexavalent chromium from tannery effluent Abs: Two bacterial consortia were developed by continuous enrichment of microbial population of tannery and pulp and paper mill effluent contained Serratia mercascens, Pseudomonas fluorescence, Escherichia coli, Pseudomonas aeruginosa and Acinetobacter sp. identified by 16S rDNA method. The consortia evaluated for removal of chromate [(Cr(VI)] in shake flask culture indicated pulp and paper mill consortium had more potential for removal of chromate. Acinetobacter sp. isolated from pulp and paper mill consortium removed higher amount of chromate [Cr(VI)] under aerobic conditions. Parameters optimized in different carbon, nitrogen sources, and pH, indicated maximum removal of chromate in sodium acetate (0.2%), sodium nitrate (0.1%) and pH 7 by Acinetobacter sp. Bacteria was applied in 2-l bioreactor significantly removed chromate after 3 days. The results of the study indicated removal of more than 75% chromium by Acinetobacter sp. determined by diphenylcarbazide colorimetric assay and atomic absorption spectrophotometer after 7 days. Study of microbial [Cr(VI)] removal and identification of reduction intermediates has been hindered by the lack of analytical techniques. Therefore, removal of chromium was further substantiated by transmission electron microscopy (TEM), scanning electron microscopy (SEM) and energy-dispersive X-ray spectroscopy (EDX) which indicated bioaccumulation of chromium in the bacterial cells."
1233676,Patton et al. 2007,Evaluation of early life stage fall chinook salmon exposed to hexavalent chromium from a contaminated groundwater source,"We conducted a laboratory evaluation to assess the risk to early life stage (i.e., eyed egg to swim up) fall Chinook salmon (Oncorhynchus tshawytscha) for exposure to hexavalent chromium from a contaminated groundwater source. Local populations of fall Chinook salmon were exposed to Hanford Site source groundwater that was diluted with Columbia River water. Specific endpoints included survival, development rate, and growth. Tissue burdens of fish were also measured to estimate uptake and elimination rates of chromium. Survival, development, and growth of early life stage fall Chinook salmon were not adversely affected by extended exposures (i.e., 98 day) to hexavalent chromium ranging from 0.79 to 260 microg/l. Survival for all treatment levels and controls exceeded 98% at termination of the test. In addition, there were no differences among the mean lengths and weights of fish among all treatment groups. Whole-body concentrations of chromium in early life stage fall Chinook salmon had a typical dose-response pattern; i.e., those subjected to highest exposure concentrations and longest exposure intervals had higher tissue concentrations. Given the spatial extent of chromium concentrations at the Hanford Site, and the dynamics of the groundwater-river water interface, the current cleanup criterion of 10 microg/l chromium appear adequate to protect early life stage fall Chinook salmon. These findings, together with previous research indicate low risk to these populations.","Evaluation of early life stage fall chinook salmon exposed to hexavalent chromium from a contaminated groundwater source Abs: We conducted a laboratory evaluation to assess the risk to early life stage (i.e., eyed egg to swim up) fall Chinook salmon (Oncorhynchus tshawytscha) for exposure to hexavalent chromium from a contaminated groundwater source. Local populations of fall Chinook salmon were exposed to Hanford Site source groundwater that was diluted with Columbia River water. Specific endpoints included survival, development rate, and growth. Tissue burdens of fish were also measured to estimate uptake and elimination rates of chromium. Survival, development, and growth of early life stage fall Chinook salmon were not adversely affected by extended exposures (i.e., 98 day) to hexavalent chromium ranging from 0.79 to 260 microg/l. Survival for all treatment levels and controls exceeded 98% at termination of the test. In addition, there were no differences among the mean lengths and weights of fish among all treatment groups. Whole-body concentrations of chromium in early life stage fall Chinook salmon had a typical dose-response pattern; i.e., those subjected to highest exposure concentrations and longest exposure intervals had higher tissue concentrations. Given the spatial extent of chromium concentrations at the Hanford Site, and the dynamics of the groundwater-river water interface, the current cleanup criterion of 10 microg/l chromium appear adequate to protect early life stage fall Chinook salmon. These findings, together with previous research indicate low risk to these populations."
1233675,Fatima and  Mahmood 2007,Vitamin C attenuates potassium dichromate-induced nephrotoxicity and alterations in renal brush border membrane enzymes and phosphate transport in rats,"<strong>BACKGROUND: </strong>Exposure to chromium compounds can result in nephrotoxicity. The administration of potassium dichromate (K(2)Cr(2)O(7)), a hexavalent chromium compound, results in impairment in functions of renal brush border membrane (BBM).<br /><br /><strong>METHODS: </strong>The effect of vitamin C (ascorbic acid) on K(2)Cr(2)O(7)-induced nephrotoxicity, changes in BBM enzymes, Pi transport and the anti-oxidant status of rat kidney were studied. Animals were divided into 4 groups and were intraperitoneally given saline (control), vitamin C alone, K(2)Cr(2)O(7) alone and vitamin C plus K(2)Cr(2)O(7). Nephrotoxicity was evaluated by urea and creatinine levels in the serum. Anti-oxidant status was evaluated in kidney homogenates.<br /><br /><strong>RESULTS: </strong>A single dose of K(2)Cr(2)O(7) (15 mg/kg body weight) resulted in an increase of serum urea nitrogen and creatinine levels, increase in lipid peroxidation and decrease in total sulfhydryl groups. However, prior treatment with a single dose of vitamin C (250 mg/kg body weight) protected the kidney from the damaging effects of K(2)Cr(2)O(7). It greatly ameliorated the K(2)Cr(2)O(7)-induced nephrotoxicity and reduction in Pi transport, activities of catalase, Cu-Zn superoxide dismutase and BBM enzymes. This was accompanied by decrease in lipid peroxidation and recovery of sulfhydryl content of renal cortex.<br /><br /><strong>CONCLUSIONS: </strong>Vitamin C is an effective chemoprotectant against K(2)Cr(2)O(7)-induced acute renal failure and dysfunction of the renal BBM in rats.","Vitamin C attenuates potassium dichromate-induced nephrotoxicity and alterations in renal brush border membrane enzymes and phosphate transport in rats Abs: <strong>BACKGROUND: </strong>Exposure to chromium compounds can result in nephrotoxicity. The administration of potassium dichromate (K(2)Cr(2)O(7)), a hexavalent chromium compound, results in impairment in functions of renal brush border membrane (BBM).<br /><br /><strong>METHODS: </strong>The effect of vitamin C (ascorbic acid) on K(2)Cr(2)O(7)-induced nephrotoxicity, changes in BBM enzymes, Pi transport and the anti-oxidant status of rat kidney were studied. Animals were divided into 4 groups and were intraperitoneally given saline (control), vitamin C alone, K(2)Cr(2)O(7) alone and vitamin C plus K(2)Cr(2)O(7). Nephrotoxicity was evaluated by urea and creatinine levels in the serum. Anti-oxidant status was evaluated in kidney homogenates.<br /><br /><strong>RESULTS: </strong>A single dose of K(2)Cr(2)O(7) (15 mg/kg body weight) resulted in an increase of serum urea nitrogen and creatinine levels, increase in lipid peroxidation and decrease in total sulfhydryl groups. However, prior treatment with a single dose of vitamin C (250 mg/kg body weight) protected the kidney from the damaging effects of K(2)Cr(2)O(7). It greatly ameliorated the K(2)Cr(2)O(7)-induced nephrotoxicity and reduction in Pi transport, activities of catalase, Cu-Zn superoxide dismutase and BBM enzymes. This was accompanied by decrease in lipid peroxidation and recovery of sulfhydryl content of renal cortex.<br /><br /><strong>CONCLUSIONS: </strong>Vitamin C is an effective chemoprotectant against K(2)Cr(2)O(7)-induced acute renal failure and dysfunction of the renal BBM in rats."
1233674,Gavin et al. 2007,Identification of human cell responses to hexavalent chromium,"Hexavalent chromium [Cr(VI)] is a recognized environmental toxin with ubiquitous distribution in industrialized societies. Its concentration in ambient air derives from several sources including but not limited to chemical processes, the burning of fossil fuels and the production of cement. It is a food contaminant because of its deposition into bodies of water. The majority of published studies on the effects of Cr(VI) concern animal models and these studies have shown that it can induce a variety of cytotoxic and genotoxic reactions that affect the immune system. In order to identify the specific cellular impact of Cr(VI) on humans, we studied its effect on protein production and gene expression in human peripheral blood mononuclear cells (PBMC) obtained from both men and women of each major ethnic group including Caucasians, Hispanics, Asians and African-Americans. High-throughput protein profiling using bead-based protein arrays showed a concentration-dependent biphasic effect of Cr(VI) on the expression of many cytokines and chemokines by activated PBMC. High-density oligonucleotide microarray analysis identified several functional families of genes including those involved in immune response, intracellular signaling, cell cycle, apoptosis, RNA transport and binding, organelle organization and biogenesis that were strongly affected by Cr(VI). Cr(VI) suppressed many cellular receptor genes involved in immune response and activated many cell cycle-related and proapoptotic genes. These results defined responses that were unique to Cr(VI). This methodology defined an effective manner for identifying injurious/toxic human exposures to Cr(VI) at the cellular level that may facilitate the identification and monitoring of efficacious treatments for Cr(VI)-related maladies.","Identification of human cell responses to hexavalent chromium Abs: Hexavalent chromium [Cr(VI)] is a recognized environmental toxin with ubiquitous distribution in industrialized societies. Its concentration in ambient air derives from several sources including but not limited to chemical processes, the burning of fossil fuels and the production of cement. It is a food contaminant because of its deposition into bodies of water. The majority of published studies on the effects of Cr(VI) concern animal models and these studies have shown that it can induce a variety of cytotoxic and genotoxic reactions that affect the immune system. In order to identify the specific cellular impact of Cr(VI) on humans, we studied its effect on protein production and gene expression in human peripheral blood mononuclear cells (PBMC) obtained from both men and women of each major ethnic group including Caucasians, Hispanics, Asians and African-Americans. High-throughput protein profiling using bead-based protein arrays showed a concentration-dependent biphasic effect of Cr(VI) on the expression of many cytokines and chemokines by activated PBMC. High-density oligonucleotide microarray analysis identified several functional families of genes including those involved in immune response, intracellular signaling, cell cycle, apoptosis, RNA transport and binding, organelle organization and biogenesis that were strongly affected by Cr(VI). Cr(VI) suppressed many cellular receptor genes involved in immune response and activated many cell cycle-related and proapoptotic genes. These results defined responses that were unique to Cr(VI). This methodology defined an effective manner for identifying injurious/toxic human exposures to Cr(VI) at the cellular level that may facilitate the identification and monitoring of efficacious treatments for Cr(VI)-related maladies."
1233673,Rafael et al. 2007,A role for transforming growth factor-beta apoptotic signaling pathway in liver injury induced by ingestion of water contaminated with high levels of Cr(VI),"Hexavalent chromium [Cr(VI)] exposure is commonly associated with lung cancer. Although other adverse health effects have been reported, some authors, on assuming that orally ingested Cr(VI) is efficiently detoxified upon reduction by body fluids, believe that Cr(VI) do not target cells other than respiratory tract cells. In rodents, ingested Cr(VI)-contaminated water was reported to induce, in the liver, increases in TGF-beta transcripts. As TGF-beta dependent signaling pathways are closely associated with hepatic injury, the present study was undertaken addressing two specific issues: the effects of ingestion of water contaminated with high levels of Cr(VI) in rat liver structure and function; and the role of the TGF-beta pathway in Cr(VI)-induced liver injury. Examination of Wistar rats exposed to 20 ppm Cr(VI)-contaminated water for 10 weeks showed increased serum glucose and alanine aminotransferase (ALT) levels. Liver histological examination revealed hepatocellular apoptosis, further confirmed by immunohystochemical study of Caspase 3 expression. Liver gene expression analysis revealed increased expression of Smad2/Smad4 and Dapk, suggesting the involvement of the TGF-beta pathway in the apoptotic process. Since no changes in Smad3 expression were observed it appears apoptosis is using a Smad3-independent pathway. Increased expression of both Caspase 8 and Daxx genes suggests also the involvement of the Fas pathway. Gene expression analysis also revealed that a p160(ROCK)-Rho-independent pathway operates, leading to cell contraction and membrane blebbing, characteristic apoptotic features. These findings suggest that either the amount of Cr(VI) ingested overwhelmed the body fluids reductive capacity or some Cr(VI) escapes the reductive protection barrier, thus targeting the liver and inducing apoptosis.","A role for transforming growth factor-beta apoptotic signaling pathway in liver injury induced by ingestion of water contaminated with high levels of Cr(VI) Abs: Hexavalent chromium [Cr(VI)] exposure is commonly associated with lung cancer. Although other adverse health effects have been reported, some authors, on assuming that orally ingested Cr(VI) is efficiently detoxified upon reduction by body fluids, believe that Cr(VI) do not target cells other than respiratory tract cells. In rodents, ingested Cr(VI)-contaminated water was reported to induce, in the liver, increases in TGF-beta transcripts. As TGF-beta dependent signaling pathways are closely associated with hepatic injury, the present study was undertaken addressing two specific issues: the effects of ingestion of water contaminated with high levels of Cr(VI) in rat liver structure and function; and the role of the TGF-beta pathway in Cr(VI)-induced liver injury. Examination of Wistar rats exposed to 20 ppm Cr(VI)-contaminated water for 10 weeks showed increased serum glucose and alanine aminotransferase (ALT) levels. Liver histological examination revealed hepatocellular apoptosis, further confirmed by immunohystochemical study of Caspase 3 expression. Liver gene expression analysis revealed increased expression of Smad2/Smad4 and Dapk, suggesting the involvement of the TGF-beta pathway in the apoptotic process. Since no changes in Smad3 expression were observed it appears apoptosis is using a Smad3-independent pathway. Increased expression of both Caspase 8 and Daxx genes suggests also the involvement of the Fas pathway. Gene expression analysis also revealed that a p160(ROCK)-Rho-independent pathway operates, leading to cell contraction and membrane blebbing, characteristic apoptotic features. These findings suggest that either the amount of Cr(VI) ingested overwhelmed the body fluids reductive capacity or some Cr(VI) escapes the reductive protection barrier, thus targeting the liver and inducing apoptosis."
1233672,Panda 2007,Chromium-mediated oxidative stress and ultrastructural changes in root cells of developing rice seedlings,"Oxidative stress and ultrastructural changes under hexavalent chromium stress were investigated in developing rice seedlings. Chromium treatment for 24 or 48h resulted in inhibition of root length and dry biomass. Atomic absorption spectrometry analysis of roots showed that chromium accumulation increased with increase in concentration and duration of metal treatment. Chromium resulted in increased production of hydrogen peroxide and superoxide radical in root cells, which was a significant change after 48h of treatment. Time-course analysis of malondialdehyde content showed no substantial variation during early treatment periods (2, 6 or 12h). Increase in malondialdehyde content was observed only after 18h and it continued to increase until 48h after treatment. Loss of membrane integrity, analyzed in terms of Evans blue uptake in root cells, showed an increase in uptake of the reagent, indicating loss of membrane integrity. The antioxidant enzyme, viz., guaiacol peroxidase, was least affected, while glutathione reductase showed significant decline after 24 or 48h of metal treatment, followed by increased activity of superoxide dismutase. The level of ascorbate was not affected by chromium, while an increase in the level of glutathione was observed. At the ultrastructural level, potential damage to the root cell was noted after 48h at 100microM of chromium compared with controls.","Chromium-mediated oxidative stress and ultrastructural changes in root cells of developing rice seedlings Abs: Oxidative stress and ultrastructural changes under hexavalent chromium stress were investigated in developing rice seedlings. Chromium treatment for 24 or 48h resulted in inhibition of root length and dry biomass. Atomic absorption spectrometry analysis of roots showed that chromium accumulation increased with increase in concentration and duration of metal treatment. Chromium resulted in increased production of hydrogen peroxide and superoxide radical in root cells, which was a significant change after 48h of treatment. Time-course analysis of malondialdehyde content showed no substantial variation during early treatment periods (2, 6 or 12h). Increase in malondialdehyde content was observed only after 18h and it continued to increase until 48h after treatment. Loss of membrane integrity, analyzed in terms of Evans blue uptake in root cells, showed an increase in uptake of the reagent, indicating loss of membrane integrity. The antioxidant enzyme, viz., guaiacol peroxidase, was least affected, while glutathione reductase showed significant decline after 24 or 48h of metal treatment, followed by increased activity of superoxide dismutase. The level of ascorbate was not affected by chromium, while an increase in the level of glutathione was observed. At the ultrastructural level, potential damage to the root cell was noted after 48h at 100microM of chromium compared with controls."
1233671,Wise et al. 2008,Hexavalent chromium is cytotoxic and genotoxic to the North Atlantic right whale (Eubalaena glacialis) lung and testes fibroblasts,"Although hexavalent chromium is a known genotoxic agent in human and terrestrial mammals and is present in seawater and air, its effects on marine mammals including the endangered North Atlantic right whale are unknown and untested. The present study investigated the cytotoxic and genotoxic effects of hexavalent chromium in primary cultured North Atlantic right whale lung and testes fibroblasts and levels of total chromium in skin biopsies from North Atlantic right whales. Cytotoxicity was measured by clonogenic survival assay. Genotoxicity was measured as production of chromosome aberrations. Tissue chromium levels were determined from skin biopsies of healthy free-ranging whales in the Bay of Fundy using inductively coupled plasma optical emission spectroscopy. Hexavalent chromium-induced concentration-dependent increases in right whale lung and testes fibroblast cytotoxicity with the testes more sensitive to the cytotoxic effects. It also induced concentration-dependent increases in chromosomal aberrations in both cell types with no significant difference in sensitivity. Skin biopsy data indicate that North Atlantic right whales are exposed to chromium and accumulate a range of 4.9-10 microg Cr/g tissue with a mean of 7.1 microg/g. Hexavalent chromium is cytotoxic and genotoxic to North Atlantic right whale cells. The whales have tissue chromium levels that are concerning. These data support a hypothesis that chromium may be a concern for the health of the North Atlantic right whales. Considering these data with chromium chemistry, whale physiology and atmospheric chromium levels further suggest that inhalation may be an important exposure route.","Hexavalent chromium is cytotoxic and genotoxic to the North Atlantic right whale (Eubalaena glacialis) lung and testes fibroblasts Abs: Although hexavalent chromium is a known genotoxic agent in human and terrestrial mammals and is present in seawater and air, its effects on marine mammals including the endangered North Atlantic right whale are unknown and untested. The present study investigated the cytotoxic and genotoxic effects of hexavalent chromium in primary cultured North Atlantic right whale lung and testes fibroblasts and levels of total chromium in skin biopsies from North Atlantic right whales. Cytotoxicity was measured by clonogenic survival assay. Genotoxicity was measured as production of chromosome aberrations. Tissue chromium levels were determined from skin biopsies of healthy free-ranging whales in the Bay of Fundy using inductively coupled plasma optical emission spectroscopy. Hexavalent chromium-induced concentration-dependent increases in right whale lung and testes fibroblast cytotoxicity with the testes more sensitive to the cytotoxic effects. It also induced concentration-dependent increases in chromosomal aberrations in both cell types with no significant difference in sensitivity. Skin biopsy data indicate that North Atlantic right whales are exposed to chromium and accumulate a range of 4.9-10 microg Cr/g tissue with a mean of 7.1 microg/g. Hexavalent chromium is cytotoxic and genotoxic to North Atlantic right whale cells. The whales have tissue chromium levels that are concerning. These data support a hypothesis that chromium may be a concern for the health of the North Atlantic right whales. Considering these data with chromium chemistry, whale physiology and atmospheric chromium levels further suggest that inhalation may be an important exposure route."
1233670,Levitskaia et al. 2008,Direct spectrophotometric analysis of Cr(VI) using a liquid waveguide capillary cell,"Hexavalent chromium Cr(VI) is a notorious ground water contaminant toxic to humans and animals. Assessment of an exposure risk for aquatic receptors necessitates frequent Cr(VI) concentration data from a range of surface and groundwater locations at Cr(VI) contamination sites. In this work, we demonstrate that enhanced ultraviolet-visible (UV-vis) spectroscopy using a liquid waveguide capillary cell (LWCC) offers an easy-to-use and economical methodology for the determination of chromate anion CrO(4)(2-) in Hanford natural waters without chemical pretreatment and generation of hazardous waste. Direct determination of CrO(4)(2-) in actual surface and ground water samples with the complexities of competing ions, dissolved organics, and other potential interfering agents was achieved by measuring the chromate optical absorbance at 372 nm. For a 100 cm path length LWCC, the detection limit for chromate was found to be as low as 0.073 ppb. A quantitative relationship between the intensity of the absorbance signal and water pH allowed for the straightforward calculation of total Cr(VI) content in natural water. The described method is applicable for in-field monitoring of Cr(VI) in environmental water samples at trace levels.","Direct spectrophotometric analysis of Cr(VI) using a liquid waveguide capillary cell Abs: Hexavalent chromium Cr(VI) is a notorious ground water contaminant toxic to humans and animals. Assessment of an exposure risk for aquatic receptors necessitates frequent Cr(VI) concentration data from a range of surface and groundwater locations at Cr(VI) contamination sites. In this work, we demonstrate that enhanced ultraviolet-visible (UV-vis) spectroscopy using a liquid waveguide capillary cell (LWCC) offers an easy-to-use and economical methodology for the determination of chromate anion CrO(4)(2-) in Hanford natural waters without chemical pretreatment and generation of hazardous waste. Direct determination of CrO(4)(2-) in actual surface and ground water samples with the complexities of competing ions, dissolved organics, and other potential interfering agents was achieved by measuring the chromate optical absorbance at 372 nm. For a 100 cm path length LWCC, the detection limit for chromate was found to be as low as 0.073 ppb. A quantitative relationship between the intensity of the absorbance signal and water pH allowed for the straightforward calculation of total Cr(VI) content in natural water. The described method is applicable for in-field monitoring of Cr(VI) in environmental water samples at trace levels."
1233669,Di Gioacchino et al. 2008,Autophagy as an ultrastructural marker of heavy metal toxicity in human cord blood hematopoietic stem cells,"Stem cells are a key target of environmental toxicants, but little is known about their toxicological responses. We aimed at developing an in-vitro model based on adult human stem cells to identify biomarkers of heavy metal exposure. To this end we investigated the responses of human CD34+ hematopoietic progenitor cells to hexavalent chromium (Cr[VI]) and cadmium (Cd). Parallel cultures of CD34+ cells isolated from umbilical cord blood were exposed for 48 h to 0.1 microM and 10 microM Cr(VI) or Cd. Cultures treated with 10 microM Cr(VI) or Cd showed marked cell loss. Ultrastructural analysis of surviving cells revealed prominent autophagosomes/autophagolysosomes, which is diagnostic of autophagy, associated with mitochondrial damage and replication, dilatation of the rough endoplasmic reticulum and Golgi complex, cytoplasmic lipid droplets and chromatin condensation. Treated cells did not show the morphologic hallmarks of apoptosis. Treatment with 0.1 microM Cr(VI) or Cd did not result in cell loss, but at the ultrastructural level cells showed dilated endoplasmic reticulum and evidence of mitochondrial damage. We conclude that autophagy is implicated in the response of human hematopoietic stem cells to toxic concentrations of Cr(VI) and Cd. Autophagy, which mediates cell survival and death under stress, deserves further evaluation to be established as biomarker of metal exposure.","Autophagy as an ultrastructural marker of heavy metal toxicity in human cord blood hematopoietic stem cells Abs: Stem cells are a key target of environmental toxicants, but little is known about their toxicological responses. We aimed at developing an in-vitro model based on adult human stem cells to identify biomarkers of heavy metal exposure. To this end we investigated the responses of human CD34+ hematopoietic progenitor cells to hexavalent chromium (Cr[VI]) and cadmium (Cd). Parallel cultures of CD34+ cells isolated from umbilical cord blood were exposed for 48 h to 0.1 microM and 10 microM Cr(VI) or Cd. Cultures treated with 10 microM Cr(VI) or Cd showed marked cell loss. Ultrastructural analysis of surviving cells revealed prominent autophagosomes/autophagolysosomes, which is diagnostic of autophagy, associated with mitochondrial damage and replication, dilatation of the rough endoplasmic reticulum and Golgi complex, cytoplasmic lipid droplets and chromatin condensation. Treated cells did not show the morphologic hallmarks of apoptosis. Treatment with 0.1 microM Cr(VI) or Cd did not result in cell loss, but at the ultrastructural level cells showed dilated endoplasmic reticulum and evidence of mitochondrial damage. We conclude that autophagy is implicated in the response of human hematopoietic stem cells to toxic concentrations of Cr(VI) and Cd. Autophagy, which mediates cell survival and death under stress, deserves further evaluation to be established as biomarker of metal exposure."
1233666,Li et al. 2008,Low-cost supports used to immobilize fungi and reliable technique for removal hexavalent chromium in wastewater,"The main goal of this study was to exploit low-cost and efficient sorbents for the removal and recovery of Cr(VI) in wastewater. Three supports of sawdust, polyurethane and alginate were applied to immobilize living and dead R. cohnii cells, respectively. There was a distinct increase in the Cr(VI) removal efficiency before and after the HCl-pretreatment. Langmuir adsorption isotherm model was well used to describe the distribution of Cr(VI) between the liquid and solid phases in batch studies. The values of q0 predicted by Thomas model were near to experimental ones in the experiments of packed column. The breakthrough curves calculated with this model were consistent well with experimental ones at a largely extent. Desorption, regeneration and reuse of the packed column were studied. After 5 cycles, adsorption capacity was still kept at higher level, reaching to 91.4, 87.9, 91.4 and 93.3mg/l contrasted with the first cycle (94.1, 90.4, 94.8 and 98.5mg/l) and the desorption efficiency were 85.0%, 96.2%, 93.4% and 91.4% compared with the first cycle (87.6%, 95.4%, 96.7% and 94.3%), corresponding to living cells immobilized with sawdust, polyurethane, and dead cells immobilized with polyurethane and alginate, respectively. The results indicated that the packed columns with the immobilized living and dead R. cohnii cells were the better option to adsorb, desorb and recover Cr(VI) from wastewater.","Low-cost supports used to immobilize fungi and reliable technique for removal hexavalent chromium in wastewater Abs: The main goal of this study was to exploit low-cost and efficient sorbents for the removal and recovery of Cr(VI) in wastewater. Three supports of sawdust, polyurethane and alginate were applied to immobilize living and dead R. cohnii cells, respectively. There was a distinct increase in the Cr(VI) removal efficiency before and after the HCl-pretreatment. Langmuir adsorption isotherm model was well used to describe the distribution of Cr(VI) between the liquid and solid phases in batch studies. The values of q0 predicted by Thomas model were near to experimental ones in the experiments of packed column. The breakthrough curves calculated with this model were consistent well with experimental ones at a largely extent. Desorption, regeneration and reuse of the packed column were studied. After 5 cycles, adsorption capacity was still kept at higher level, reaching to 91.4, 87.9, 91.4 and 93.3mg/l contrasted with the first cycle (94.1, 90.4, 94.8 and 98.5mg/l) and the desorption efficiency were 85.0%, 96.2%, 93.4% and 91.4% compared with the first cycle (87.6%, 95.4%, 96.7% and 94.3%), corresponding to living cells immobilized with sawdust, polyurethane, and dead cells immobilized with polyurethane and alginate, respectively. The results indicated that the packed columns with the immobilized living and dead R. cohnii cells were the better option to adsorb, desorb and recover Cr(VI) from wastewater."
1233665,Klonowska et al. 2008,Hexavalent chromium reduction in Desulfovibrio vulgaris Hildenborough causes transitory inhibition of sulfate reduction and cell growth,"Desulfovibrio vulgaris Hildenborough is a well-studied sulfate reducer that can reduce heavy metals and radionuclides [e.g., Cr(VI) and U(VI)]. Cultures grown in a defined medium had a lag period of approximately 30 h when exposed to 0.05 mM Cr(VI). Substrate analyses revealed that although Cr(VI) was reduced within the first 5 h, growth was not observed for an additional 20 h. The growth lag could be explained by a decline in cell viability; however, during this time small amounts of lactate were still utilized without sulfate reduction or acetate formation. Approximately 40 h after Cr exposure (0.05 mM), sulfate reduction occurred concurrently with the accumulation of acetate. Similar amounts of hydrogen were produced by Cr-exposed cells compared to control cells, and lactate was not converted to glycogen during non-growth conditions. D. vulgaris cells treated with a reducing agent and then exposed to Cr(VI) still experienced a growth lag, but the addition of ascorbate at the time of Cr(VI) addition prevented the lag period. In addition, cells grown on pyruvate displayed more tolerance to Cr(VI) compared to lactate-grown cells. These results indicated that D. vulgaris utilized lactate during Cr(VI) exposure without the reduction of sulfate or production of acetate, and that ascorbate and pyruvate could protect D. vulgaris cells from Cr(VI)/Cr(III) toxicity.","Hexavalent chromium reduction in Desulfovibrio vulgaris Hildenborough causes transitory inhibition of sulfate reduction and cell growth Abs: Desulfovibrio vulgaris Hildenborough is a well-studied sulfate reducer that can reduce heavy metals and radionuclides [e.g., Cr(VI) and U(VI)]. Cultures grown in a defined medium had a lag period of approximately 30 h when exposed to 0.05 mM Cr(VI). Substrate analyses revealed that although Cr(VI) was reduced within the first 5 h, growth was not observed for an additional 20 h. The growth lag could be explained by a decline in cell viability; however, during this time small amounts of lactate were still utilized without sulfate reduction or acetate formation. Approximately 40 h after Cr exposure (0.05 mM), sulfate reduction occurred concurrently with the accumulation of acetate. Similar amounts of hydrogen were produced by Cr-exposed cells compared to control cells, and lactate was not converted to glycogen during non-growth conditions. D. vulgaris cells treated with a reducing agent and then exposed to Cr(VI) still experienced a growth lag, but the addition of ascorbate at the time of Cr(VI) addition prevented the lag period. In addition, cells grown on pyruvate displayed more tolerance to Cr(VI) compared to lactate-grown cells. These results indicated that D. vulgaris utilized lactate during Cr(VI) exposure without the reduction of sulfate or production of acetate, and that ascorbate and pyruvate could protect D. vulgaris cells from Cr(VI)/Cr(III) toxicity."
1233664,Lai and  Lo 2008,Removal of chromium (VI) by acid-washed zero-valent iron under various groundwater geochemistry conditions,"The hexavalent chromium (Cr(VI)) removal capacity of acid-washed zerovalent iron (AW-Fe0) was evaluated under different groundwater geochemistry conditions through column experiments. It was found that each gram of the AW-Fe0 could remove 0.65-1.76 mg of Cr(VI) from synthetic groundwater in the absence of bicarbonate (HCO3-), magnesium and/or calcium ions. Groundwater geochemistry was found to exert various degrees of impact on Cr(VI) removal by the AW-Fe0, in which HCO3- alone gave the mildest impact whereas the copresence of calcium and HCO3- exerted the greatest impact In comparison with the unwashed Fe0, the AW-Fe0 showed a poorer Cr(VI) removal capacity and was also more susceptible to the influence of the dissolved groundwater constituents on Cr(VI) removal,thereby indicating the unsuitability of using AW-Fe0 in permeable reactive barriers for remediation of Cr(VI)-contaminated groundwater. On the AW-Fe0 surface, where the indigenous iron precipitates were almost erased, trivalent chromium including chromium (III) oxides, hydroxides, and oxyhydroxides in irregular strip, chick footmark-liked or boulder-liked forms as well as Cr(III)-Cr(VI) mixed oxides were detected.","Removal of chromium (VI) by acid-washed zero-valent iron under various groundwater geochemistry conditions Abs: The hexavalent chromium (Cr(VI)) removal capacity of acid-washed zerovalent iron (AW-Fe0) was evaluated under different groundwater geochemistry conditions through column experiments. It was found that each gram of the AW-Fe0 could remove 0.65-1.76 mg of Cr(VI) from synthetic groundwater in the absence of bicarbonate (HCO3-), magnesium and/or calcium ions. Groundwater geochemistry was found to exert various degrees of impact on Cr(VI) removal by the AW-Fe0, in which HCO3- alone gave the mildest impact whereas the copresence of calcium and HCO3- exerted the greatest impact In comparison with the unwashed Fe0, the AW-Fe0 showed a poorer Cr(VI) removal capacity and was also more susceptible to the influence of the dissolved groundwater constituents on Cr(VI) removal,thereby indicating the unsuitability of using AW-Fe0 in permeable reactive barriers for remediation of Cr(VI)-contaminated groundwater. On the AW-Fe0 surface, where the indigenous iron precipitates were almost erased, trivalent chromium including chromium (III) oxides, hydroxides, and oxyhydroxides in irregular strip, chick footmark-liked or boulder-liked forms as well as Cr(III)-Cr(VI) mixed oxides were detected."
1233663,Goodale et al. 2008,The cytotoxicity and genotoxicity of hexavalent chromium in medaka (Oryzias latipes) cells,"Chromium is an increasing health concern for aquatic environments, however, the mechanism of chromium toxicity in aquatic species is yet unknown. We used a medaka (Oryzias latipes) fin cell line to investigate the cytotoxicity and genotoxicity of sodium chromate, a soluble form of hexavalent chromium. We used a clonogenic cytotoxicity assay to measure sodium chromate cytotoxicity, gamma-H2A.X immunofluoresence to measure DNA double-strand breaks, and chromosome damage to measure clastogenicity. We found that sodium chromate is cytotoxic to medaka fin cells, with toxicity increasing in a concentration-dependent manner. Treatments of 0.5, 1, 5, 10, 25, 50 and 100 microM sodium chromate caused 100, 103.5, 87.8, 77.5, 40.9, 15 and 2.7% survival, respectively, relative to the control. We visualized DNA double-strand breaks in medaka cells through the formation of gamma-H2A.X foci. Breaks could be detected at concentrations as low as 1 microM. We also found that sodium chromate induces chromosomal aberrations, causing chromatid lesions and exchanges that increase with concentration. Treatments of 0, 1, 5, 10 and 25 microM sodium chromate damaged 10.3, 17, 32.3, 43 and 51.6% of metaphases and induced 13, 23, 44, 69 and 118 total aberrations in 100 metaphases, respectively. These data show that hexavalent chromium is both cytotoxic and genotoxic to fish cells. Our results set the context for future work in the medaka cell culture model and provide important tools for investigating mechanisms of toxicity in aquatic organisms.","The cytotoxicity and genotoxicity of hexavalent chromium in medaka (Oryzias latipes) cells Abs: Chromium is an increasing health concern for aquatic environments, however, the mechanism of chromium toxicity in aquatic species is yet unknown. We used a medaka (Oryzias latipes) fin cell line to investigate the cytotoxicity and genotoxicity of sodium chromate, a soluble form of hexavalent chromium. We used a clonogenic cytotoxicity assay to measure sodium chromate cytotoxicity, gamma-H2A.X immunofluoresence to measure DNA double-strand breaks, and chromosome damage to measure clastogenicity. We found that sodium chromate is cytotoxic to medaka fin cells, with toxicity increasing in a concentration-dependent manner. Treatments of 0.5, 1, 5, 10, 25, 50 and 100 microM sodium chromate caused 100, 103.5, 87.8, 77.5, 40.9, 15 and 2.7% survival, respectively, relative to the control. We visualized DNA double-strand breaks in medaka cells through the formation of gamma-H2A.X foci. Breaks could be detected at concentrations as low as 1 microM. We also found that sodium chromate induces chromosomal aberrations, causing chromatid lesions and exchanges that increase with concentration. Treatments of 0, 1, 5, 10 and 25 microM sodium chromate damaged 10.3, 17, 32.3, 43 and 51.6% of metaphases and induced 13, 23, 44, 69 and 118 total aberrations in 100 metaphases, respectively. These data show that hexavalent chromium is both cytotoxic and genotoxic to fish cells. Our results set the context for future work in the medaka cell culture model and provide important tools for investigating mechanisms of toxicity in aquatic organisms."
1233659,Loyo et al. 2008,Immobilization of selenite on Fe3O4 and Fe/Fe3C ultrasmall particles,"The sorption of selenite ions onto Fe3O4 and Fe/Fe3C nanoparticles (NPs) was studied in aqueous solutions under anoxic conditions using gamma spectrometry and X-ray absorption spectrometry (XAS) techniques. This is the first study related to the remedial applications of Fe/Fe3C NPs. FesO4 NPs have been prepared by conventional coprecipitation of Fe(II) and Fe(III) in basic solutions. Stable Fe/Fe3C NPs have been prepared by Fe(CO)5 sonicating in diphenylmethane solutions and subsequently annealing the as-prepared product. Kinetic study demonstrated that Se(IV) sorption is extremely rapid: the equilibrium is reached in approximately 10 and 30 min for Fe3O4 and Fe/Fe3C NPs, respectively, at pH = 4.9-5.1 in solutions of 0.1 M NaCl. The distribution coefficients are also very high for both kinds of NPs (Kd &gt; 3000). Increasing the pH to 10.3 or adsorption of organic ligands, like L-lysine or dodecanoate, at the surface of NPs causes the decrease in Kd values. However, even in these cases Kd values exceed 150. Magnetic NPs loaded with selenium can be easily and completely removed from solution with a 0.4 T permanent magnet. XAS study revealed the absence of Se(IV) reduction during the sorption onto Fe3O4 NPs in the pH range of 4.8-8.0. By contrast, the removal of Se(IV) with Fe/Fe3C NPs in anaerobic conditions occurs via Se(IV) reduction to Se(-II) and subsequent formation of iron selenide at the particle surface. Thus, the Fe/Fe3C NPs are superior to Fe3O4 NPs due to their ability to immobilize rapidly and irreversibly Se(IV) via reductive mechanism. Presumably these particles could be also effective for the removal of other contaminants such as hexavalent chromium, actinides, technetium, and toxic organic compounds.","Immobilization of selenite on Fe3O4 and Fe/Fe3C ultrasmall particles Abs: The sorption of selenite ions onto Fe3O4 and Fe/Fe3C nanoparticles (NPs) was studied in aqueous solutions under anoxic conditions using gamma spectrometry and X-ray absorption spectrometry (XAS) techniques. This is the first study related to the remedial applications of Fe/Fe3C NPs. FesO4 NPs have been prepared by conventional coprecipitation of Fe(II) and Fe(III) in basic solutions. Stable Fe/Fe3C NPs have been prepared by Fe(CO)5 sonicating in diphenylmethane solutions and subsequently annealing the as-prepared product. Kinetic study demonstrated that Se(IV) sorption is extremely rapid: the equilibrium is reached in approximately 10 and 30 min for Fe3O4 and Fe/Fe3C NPs, respectively, at pH = 4.9-5.1 in solutions of 0.1 M NaCl. The distribution coefficients are also very high for both kinds of NPs (Kd &gt; 3000). Increasing the pH to 10.3 or adsorption of organic ligands, like L-lysine or dodecanoate, at the surface of NPs causes the decrease in Kd values. However, even in these cases Kd values exceed 150. Magnetic NPs loaded with selenium can be easily and completely removed from solution with a 0.4 T permanent magnet. XAS study revealed the absence of Se(IV) reduction during the sorption onto Fe3O4 NPs in the pH range of 4.8-8.0. By contrast, the removal of Se(IV) with Fe/Fe3C NPs in anaerobic conditions occurs via Se(IV) reduction to Se(-II) and subsequent formation of iron selenide at the particle surface. Thus, the Fe/Fe3C NPs are superior to Fe3O4 NPs due to their ability to immobilize rapidly and irreversibly Se(IV) via reductive mechanism. Presumably these particles could be also effective for the removal of other contaminants such as hexavalent chromium, actinides, technetium, and toxic organic compounds."
1233658,Li et al. 2008,A novel technology for biosorption and recovery hexavalent chromium in wastewater by bio-functional magnetic beads,"The goal of this study was to develop an applied technique for the removal and recovery of heavy metal in wastewater. It is novel that the Cr(VI) could be adsorbed and recovered by bio-functional magnetic beads. Furthermore, the magnetic separation technology would make their separation more convenient. The beads were constituted by the powder of Rhizopus cohnii and Fe(3)O(4) particles coated with alginate and polyvinyl alcohol (PVA). The parameters effecting Cr(VI) removal were obtained: the optimum pH 1.0 and optimum temperature 28 degrees C. The biosorption took place mainly in form of Cr(VI) and R. cohnii biomass played a key role in Cr(VI) adsorption. The model of Langmuir isotherm and Lagergren could be better used to fit the sorption process and kinetics, respectively. The beads still maintained predominant characteristics of adsorption, recovery and magnetism after five cycles for adsorption-desorption. The mechanism of adsorption was gained by Fourier transform infrared spectroscopy (FTIR), raman spectroscopy (RS) and scanning electron microscopy (SEM). The groups of -NH(3)(+), -NH(2)(+)-, and NH- played an important role in the Cr(VI) adsorption. Consequently, the beads exhibited the superior performances in Cr(VI) cleanup, separation and recovery and the perspective potential in application.","A novel technology for biosorption and recovery hexavalent chromium in wastewater by bio-functional magnetic beads Abs: The goal of this study was to develop an applied technique for the removal and recovery of heavy metal in wastewater. It is novel that the Cr(VI) could be adsorbed and recovered by bio-functional magnetic beads. Furthermore, the magnetic separation technology would make their separation more convenient. The beads were constituted by the powder of Rhizopus cohnii and Fe(3)O(4) particles coated with alginate and polyvinyl alcohol (PVA). The parameters effecting Cr(VI) removal were obtained: the optimum pH 1.0 and optimum temperature 28 degrees C. The biosorption took place mainly in form of Cr(VI) and R. cohnii biomass played a key role in Cr(VI) adsorption. The model of Langmuir isotherm and Lagergren could be better used to fit the sorption process and kinetics, respectively. The beads still maintained predominant characteristics of adsorption, recovery and magnetism after five cycles for adsorption-desorption. The mechanism of adsorption was gained by Fourier transform infrared spectroscopy (FTIR), raman spectroscopy (RS) and scanning electron microscopy (SEM). The groups of -NH(3)(+), -NH(2)(+)-, and NH- played an important role in the Cr(VI) adsorption. Consequently, the beads exhibited the superior performances in Cr(VI) cleanup, separation and recovery and the perspective potential in application."
1233657,Okeke et al. 2008,Environmental and kinetic parameters for Cr(VI) bioreduction by a bacterial monoculture purified from Cr(VI)-resistant consortium,"Hexavalent chromium, Cr(VI), is toxic to living systems. Widespread contamination of water and soil by Cr(VI) present a serious public health problem. Chromium-resistant bacteria can reduce and detoxify Cr(VI). Twelve bacteria resistant to high concentrations of Cr(VI) were isolated from soil enrichment cultures. Environmental parameters and kinetic parameters of Cr(VI) bioreduction by one monoculture isolate, identified by 16S rRNA gene sequence as Bacillus sp. PB2, were studied. The optimal temperature for growth and Cr(VI) reduction was 35 degrees C. The isolate grew luxuriantly and substantially reduced Cr(VI) at initial pH 7.5 to 9. Maximal Cr(VI) bioreduction occurred at initial pH 8.0. Substantial Cr(VI) bioreduction was observed in salt media, but removal efficiency was inversely related to salt concentration (1-9%). Michaelis-Menten hyperbolic equation and the Lineweaver-Burk double reciprocal plot were comparatively employed to determine the k (m) and V (max) of Cr(VI) bioreduction. A k (m) of 82.5 microg mL(-1) and V (max) of 7.78 microg mL(-1) h(-1) were calculated by nonlinear regression analysis of the hyperbola curve. Linear regression analysis of the double reciprocal plot revealed k (m) and V (max) of 80.9 microg mL(-1) and 10.6 microg mL(-1) h(-1), respectively. Time course studies displayed about 90% reduction of Cr(VI) at an initial concentration of 8,000 microg L(-1) in 8 h, with an estimated t (1/2) of 4 h. Data from time course analysis of the rate of Cr(VI) bioreduction fitted zero-order model, and the kinetic constant k was calculated to be 840 microg L(-1) h(-1). The monoculture isolate, Bacillus sp. PB2, strongly reduces Cr(VI) and could be used for bioremediation of Cr(VI)-contaminated aquatic and terrestrial environments.","Environmental and kinetic parameters for Cr(VI) bioreduction by a bacterial monoculture purified from Cr(VI)-resistant consortium Abs: Hexavalent chromium, Cr(VI), is toxic to living systems. Widespread contamination of water and soil by Cr(VI) present a serious public health problem. Chromium-resistant bacteria can reduce and detoxify Cr(VI). Twelve bacteria resistant to high concentrations of Cr(VI) were isolated from soil enrichment cultures. Environmental parameters and kinetic parameters of Cr(VI) bioreduction by one monoculture isolate, identified by 16S rRNA gene sequence as Bacillus sp. PB2, were studied. The optimal temperature for growth and Cr(VI) reduction was 35 degrees C. The isolate grew luxuriantly and substantially reduced Cr(VI) at initial pH 7.5 to 9. Maximal Cr(VI) bioreduction occurred at initial pH 8.0. Substantial Cr(VI) bioreduction was observed in salt media, but removal efficiency was inversely related to salt concentration (1-9%). Michaelis-Menten hyperbolic equation and the Lineweaver-Burk double reciprocal plot were comparatively employed to determine the k (m) and V (max) of Cr(VI) bioreduction. A k (m) of 82.5 microg mL(-1) and V (max) of 7.78 microg mL(-1) h(-1) were calculated by nonlinear regression analysis of the hyperbola curve. Linear regression analysis of the double reciprocal plot revealed k (m) and V (max) of 80.9 microg mL(-1) and 10.6 microg mL(-1) h(-1), respectively. Time course studies displayed about 90% reduction of Cr(VI) at an initial concentration of 8,000 microg L(-1) in 8 h, with an estimated t (1/2) of 4 h. Data from time course analysis of the rate of Cr(VI) bioreduction fitted zero-order model, and the kinetic constant k was calculated to be 840 microg L(-1) h(-1). The monoculture isolate, Bacillus sp. PB2, strongly reduces Cr(VI) and could be used for bioremediation of Cr(VI)-contaminated aquatic and terrestrial environments."
1233656,Radivojevic and  Cooper 2008,Extraction of hexavalent chromium from chromated copper arsenate treated wood under alkaline conditions,"Information on chromium (Cr) oxidation states is essential for the assessment of environmental and health risks associated with the overall life-cycle of chromated copper arsenate (CCA) treated wood products because of differences in toxicity between trivalent [Cr(III)] and hexavalent [Cr(VI)] chromium compounds. Hypothetical Cr(VI) fixation products were investigated in CCA type C treated sawdust of aspen and red pine during or following preservative fixation by extraction with Cr(VI)-specific extractants. Cr(VI) was found only in alkaline extracts of treated wood. A major source of Cr(VI) was method-induced oxidation of fixed Cr(III) during alkaline extraction, as confirmed by demonstrated oxidation of Cr(III) from CrCl3 treated wood. Oxidation of nontoxic and immobile Cr(III) to toxic and mobile Cr(VI) was facilitated by the presence of wood at pH &gt; 8.5. Thermodynamic equilibrium between Cr(III) and Cr(VI) is affected by pH, temperature, rates of dissolution of CrIII) compounds, and oxygen availability. Results of this study recommend against alkaline extraction protocols for determination of Cr(VI) in treated wood. This Cr oxidation mechanism can act as a previously unrecognized route for generation of hazardous Cr(VI) if CCA treated wood is exposed to alkaline conditions during its production, use, or waste management.","Extraction of hexavalent chromium from chromated copper arsenate treated wood under alkaline conditions Abs: Information on chromium (Cr) oxidation states is essential for the assessment of environmental and health risks associated with the overall life-cycle of chromated copper arsenate (CCA) treated wood products because of differences in toxicity between trivalent [Cr(III)] and hexavalent [Cr(VI)] chromium compounds. Hypothetical Cr(VI) fixation products were investigated in CCA type C treated sawdust of aspen and red pine during or following preservative fixation by extraction with Cr(VI)-specific extractants. Cr(VI) was found only in alkaline extracts of treated wood. A major source of Cr(VI) was method-induced oxidation of fixed Cr(III) during alkaline extraction, as confirmed by demonstrated oxidation of Cr(III) from CrCl3 treated wood. Oxidation of nontoxic and immobile Cr(III) to toxic and mobile Cr(VI) was facilitated by the presence of wood at pH &gt; 8.5. Thermodynamic equilibrium between Cr(III) and Cr(VI) is affected by pH, temperature, rates of dissolution of CrIII) compounds, and oxygen availability. Results of this study recommend against alkaline extraction protocols for determination of Cr(VI) in treated wood. This Cr oxidation mechanism can act as a previously unrecognized route for generation of hazardous Cr(VI) if CCA treated wood is exposed to alkaline conditions during its production, use, or waste management."
1233655,Caravelli et al. 2008,Reduction of hexavalent chromium by Sphaerotilus natans a filamentous micro-organism present in activated sludges,"Wastewaters produced by various industries may contain undesirable amounts of hexavalent chromium (Cr(VI)), as chromate and dichromate, a hazardous metal affecting flora and animals of aquatic ecosystems as well as human health. One removal strategy comprises the microbial reduction of Cr(VI) to Cr(III), a less soluble chemical species that is less toxic than Cr(VI). In this work, the ability to reduce Cr(VI) of Sphaerotilus natans, a filamentous bacterium usually found in activated sludge systems, was evaluated. In aerobic conditions, S. natans was able to efficiently reduce Cr(VI) to Cr(III) from dichromate solutions ranging between 4.5 and 80 mg Cr(VI)l(-1) in the presence of a carbonaceous source. A simultaneous evaluation of the microbial respiratory activity inhibition was also carried out to analyze the toxic effect of Cr(VI). Cr(VI) reduction by S. natans was mathematically modeled; chromium(VI) reduction rate depended on both Cr(VI) concentration and active biomass concentration. Although it is known that S. natans removes heavy metal cations such as Cr(III) by biosorption, the ability of this micro-organism to reduce Cr(VI), which behaves as an oxyanion in aqueous solutions, is a novel finding. The distinctive capacity to reduce Cr(VI) to Cr(III) than remain soluble or precipitated becomes S. natans a potential micro-organism to decontaminate wastewaters.","Reduction of hexavalent chromium by Sphaerotilus natans a filamentous micro-organism present in activated sludges Abs: Wastewaters produced by various industries may contain undesirable amounts of hexavalent chromium (Cr(VI)), as chromate and dichromate, a hazardous metal affecting flora and animals of aquatic ecosystems as well as human health. One removal strategy comprises the microbial reduction of Cr(VI) to Cr(III), a less soluble chemical species that is less toxic than Cr(VI). In this work, the ability to reduce Cr(VI) of Sphaerotilus natans, a filamentous bacterium usually found in activated sludge systems, was evaluated. In aerobic conditions, S. natans was able to efficiently reduce Cr(VI) to Cr(III) from dichromate solutions ranging between 4.5 and 80 mg Cr(VI)l(-1) in the presence of a carbonaceous source. A simultaneous evaluation of the microbial respiratory activity inhibition was also carried out to analyze the toxic effect of Cr(VI). Cr(VI) reduction by S. natans was mathematically modeled; chromium(VI) reduction rate depended on both Cr(VI) concentration and active biomass concentration. Although it is known that S. natans removes heavy metal cations such as Cr(III) by biosorption, the ability of this micro-organism to reduce Cr(VI), which behaves as an oxyanion in aqueous solutions, is a novel finding. The distinctive capacity to reduce Cr(VI) to Cr(III) than remain soluble or precipitated becomes S. natans a potential micro-organism to decontaminate wastewaters."
1233654,Rehman et al. 2008,Chromium tolerance and reduction potential of a Bacillus sp.ev3 isolated from metal contaminated wastewater,"This study was aimed at assessing the ability of Bacillus sp.ev3 to reduce hexavalent chromium into its trivalent form. Bacillus sp.ev3 could tolerate Cr(6+) (4800 microg/mL), Pb(2+) (800 microg/mL), Cu(2+) (200 microg/mL), Cd(2+) (50 microg/mL), Zn(2+) (400 microg/mL), Ni(2+) (4000 microg/mL) and Hg(2+) (50 microg/mL). Bacillus sp.ev3 showed optimum growth at 37 degrees C and pH at 7. Bacillus sp.ev3 could reduce 91% of chromium from the medium after 96 h and was also capable to reduce 84% chromium from the industrial effluents after 144 h. Cell free extracts of Bacillus sp.ev3 grown in the presence of Cr showed reduction of 70%, 45.6% and 27.4% at concentrations of 10 microg Cr(6+)/mL, 50 microg Cr(6+)/mL and 100 microg Cr(6+)/mL, respectively.","Chromium tolerance and reduction potential of a Bacillus sp.ev3 isolated from metal contaminated wastewater Abs: This study was aimed at assessing the ability of Bacillus sp.ev3 to reduce hexavalent chromium into its trivalent form. Bacillus sp.ev3 could tolerate Cr(6+) (4800 microg/mL), Pb(2+) (800 microg/mL), Cu(2+) (200 microg/mL), Cd(2+) (50 microg/mL), Zn(2+) (400 microg/mL), Ni(2+) (4000 microg/mL) and Hg(2+) (50 microg/mL). Bacillus sp.ev3 showed optimum growth at 37 degrees C and pH at 7. Bacillus sp.ev3 could reduce 91% of chromium from the medium after 96 h and was also capable to reduce 84% chromium from the industrial effluents after 144 h. Cell free extracts of Bacillus sp.ev3 grown in the presence of Cr showed reduction of 70%, 45.6% and 27.4% at concentrations of 10 microg Cr(6+)/mL, 50 microg Cr(6+)/mL and 100 microg Cr(6+)/mL, respectively."
1233653,Urrutia et al. 2008,Assessment of EDTA in chromium (III-VI) toxicity on marine intertidal crab (Petrolisthes laevigatus),"Chromium poses a potential threat to coastal ecosystems. We used standard toxicity bioassays (semi-static, chronic) to evaluate EDTA as a chelating agent for reducing trivalent and hexavalent chromium toxicity on Petrolisthes laevigatus. Crab survival decreased linearly with increased chromium concentrations and dropped significantly beginning at 40 mg/L Cr (VI) and 80 mg/L Cr (III). No significant differences were observed with Cr (III) + EDTA as compared with untreated controls. Cr (VI) toxicity was greater than that of Cr (III), with low individual survival rates. The protective effect of EDTA in the medium increased crab survival by 41%-48%.","Assessment of EDTA in chromium (III-VI) toxicity on marine intertidal crab (Petrolisthes laevigatus) Abs: Chromium poses a potential threat to coastal ecosystems. We used standard toxicity bioassays (semi-static, chronic) to evaluate EDTA as a chelating agent for reducing trivalent and hexavalent chromium toxicity on Petrolisthes laevigatus. Crab survival decreased linearly with increased chromium concentrations and dropped significantly beginning at 40 mg/L Cr (VI) and 80 mg/L Cr (III). No significant differences were observed with Cr (III) + EDTA as compared with untreated controls. Cr (VI) toxicity was greater than that of Cr (III), with low individual survival rates. The protective effect of EDTA in the medium increased crab survival by 41%-48%."
1233651,Koyama et al. 2008,Java medaka: a proposed new marine test fish for ecotoxicology,"Java medaka (Oryzias javanicus), which is distributed in estuarine waters of East to Southeast Asia, is proposed here for consideration as a new marine test fish. Semi-static acute toxicity tests were conducted at 26 degrees C for 1 week, 2 weeks, and 1 month old Java-medaka exposed to 4-chlorophenol and zinc, and 2 weeks olds exposed to potassium dichromate (hexavalent chromium) and sodium hypochlorite (residue chlorine). Ninety-six hours LC50s of 4-chlorophenol, zinc, hexavalent chromium, and residue chlorine were from 3.0 to 4.1, from 12.4 to 14.7, 7.4, and 0.05 mg/L, respectively. There were no large differences in sensitivity for 4-chlorophenol and zinc among the three growth stages. Compared with other fish species, these LC50s were relatively low suggesting that Java medaka has relatively high sensitivity to chemicals. This fish is quite easy to keep in the laboratory, with low mortalities at early stages and it takes about 3 months to mature from hatching, suggesting that this fish can be used not only for short-term toxicity tests but also for early life stage toxicity tests. From these results, Java-medaka is highly recommended as a marine test fish for ecotoxicity tests.","Java medaka: a proposed new marine test fish for ecotoxicology Abs: Java medaka (Oryzias javanicus), which is distributed in estuarine waters of East to Southeast Asia, is proposed here for consideration as a new marine test fish. Semi-static acute toxicity tests were conducted at 26 degrees C for 1 week, 2 weeks, and 1 month old Java-medaka exposed to 4-chlorophenol and zinc, and 2 weeks olds exposed to potassium dichromate (hexavalent chromium) and sodium hypochlorite (residue chlorine). Ninety-six hours LC50s of 4-chlorophenol, zinc, hexavalent chromium, and residue chlorine were from 3.0 to 4.1, from 12.4 to 14.7, 7.4, and 0.05 mg/L, respectively. There were no large differences in sensitivity for 4-chlorophenol and zinc among the three growth stages. Compared with other fish species, these LC50s were relatively low suggesting that Java medaka has relatively high sensitivity to chemicals. This fish is quite easy to keep in the laboratory, with low mortalities at early stages and it takes about 3 months to mature from hatching, suggesting that this fish can be used not only for short-term toxicity tests but also for early life stage toxicity tests. From these results, Java-medaka is highly recommended as a marine test fish for ecotoxicity tests."
1233650,Quinteros et al. 2008,Mechanisms of chromium (VI)-induced apoptosis in anterior pituitary cells,"Hexavalent chromium (Cr (VI)) is a highly toxic metal. Exposure to Cr (VI) compounds may affect reproductive functions. Due to the importance of anterior pituitary hormones on reproductive physiology we have studied the effects of Cr (VI) on anterior pituitary. We previously demonstrated that, after in vivo Cr (VI) administration, Cr accumulates in the pituitary gland and affects prolactin secretion. In vitro, Cr (VI) causes apoptosis in anterior pituitary cells due to oxidative stress generation. To better understand the mechanisms involved in Cr (VI)-induced apoptosis we studied: (a) whether Cr (VI) affects the intracellular antioxidant response and (b) which of the apoptotic factors participates in Cr (VI) effect. Our results show that Cr (VI) treatment induces a decrease in catalase and glutathione peroxidase (GPx) activity but does not modify glutathione reductase (GR) activity. Cr (VI) exposure causes an increase of GSH levels. p53 and Bax mRNA are also upregulated by the metal. Pifithrin alpha, a p53 transcriptional inhibitor, increases Cr (VI) cytotoxicity, suggesting a role of p53 as a survival molecule. The antioxidant N-acetyl-cysteine (NAC) could prevent Bax mRNA increase and caspase 3 activation, confirming that Cr (VI)-induced apoptosis involves oxidative stress generation.","Mechanisms of chromium (VI)-induced apoptosis in anterior pituitary cells Abs: Hexavalent chromium (Cr (VI)) is a highly toxic metal. Exposure to Cr (VI) compounds may affect reproductive functions. Due to the importance of anterior pituitary hormones on reproductive physiology we have studied the effects of Cr (VI) on anterior pituitary. We previously demonstrated that, after in vivo Cr (VI) administration, Cr accumulates in the pituitary gland and affects prolactin secretion. In vitro, Cr (VI) causes apoptosis in anterior pituitary cells due to oxidative stress generation. To better understand the mechanisms involved in Cr (VI)-induced apoptosis we studied: (a) whether Cr (VI) affects the intracellular antioxidant response and (b) which of the apoptotic factors participates in Cr (VI) effect. Our results show that Cr (VI) treatment induces a decrease in catalase and glutathione peroxidase (GPx) activity but does not modify glutathione reductase (GR) activity. Cr (VI) exposure causes an increase of GSH levels. p53 and Bax mRNA are also upregulated by the metal. Pifithrin alpha, a p53 transcriptional inhibitor, increases Cr (VI) cytotoxicity, suggesting a role of p53 as a survival molecule. The antioxidant N-acetyl-cysteine (NAC) could prevent Bax mRNA increase and caspase 3 activation, confirming that Cr (VI)-induced apoptosis involves oxidative stress generation."
1233649,Azad et al. 2008,Superoxide-mediated proteasomal degradation of Bcl-2 determines cell susceptibility to Cr(VI)-induced apoptosis,"Hexavalent chromium [Cr(VI)] compounds are redox cycling environmental carcinogens that induce apoptosis as the primary mode of cell death. Defects in apoptosis regulatory mechanisms contribute to carcinogenesis induced by Cr(VI). Activation of apoptosis signaling pathways is tightly linked with the generation of reactive oxygen species (ROS). Likewise, ROS have been implicated in the regulation of Cr(VI)-induced apoptosis and carcinogenicity; however, its role in Cr(VI)-induced apoptosis and the underlying mechanism are largely unknown. We report that ROS, specifically superoxide anion (.O(-)(2), mediates Cr(VI)-induced apoptosis of human lung epithelial H460 cells. H460 rho(0) cells that lack mitochondrial DNA demonstrated a significant decrease in ROS production and apoptotic response to Cr(VI), indicating the involvement of mitochondrial ROS in Cr(VI)-induced apoptosis. In agreement with this observation, we found that Cr(VI) induces apoptosis mainly through the mitochondrial death pathway via caspase-9 activation, which is negatively regulated by the antiapoptotic protein Bcl-2. Furthermore, .O(-)(2) induced apoptosis in response to Cr(VI) exposure by downregulating and degrading Bcl-2 protein through the ubiquitin-proteasomal pathway. This study reveals a novel mechanism linking .O(-)(2) with Bcl-2 stability and provides a new dimension to ROS-mediated Bcl-2 downregulation and apoptosis induction.","Superoxide-mediated proteasomal degradation of Bcl-2 determines cell susceptibility to Cr(VI)-induced apoptosis Abs: Hexavalent chromium [Cr(VI)] compounds are redox cycling environmental carcinogens that induce apoptosis as the primary mode of cell death. Defects in apoptosis regulatory mechanisms contribute to carcinogenesis induced by Cr(VI). Activation of apoptosis signaling pathways is tightly linked with the generation of reactive oxygen species (ROS). Likewise, ROS have been implicated in the regulation of Cr(VI)-induced apoptosis and carcinogenicity; however, its role in Cr(VI)-induced apoptosis and the underlying mechanism are largely unknown. We report that ROS, specifically superoxide anion (.O(-)(2), mediates Cr(VI)-induced apoptosis of human lung epithelial H460 cells. H460 rho(0) cells that lack mitochondrial DNA demonstrated a significant decrease in ROS production and apoptotic response to Cr(VI), indicating the involvement of mitochondrial ROS in Cr(VI)-induced apoptosis. In agreement with this observation, we found that Cr(VI) induces apoptosis mainly through the mitochondrial death pathway via caspase-9 activation, which is negatively regulated by the antiapoptotic protein Bcl-2. Furthermore, .O(-)(2) induced apoptosis in response to Cr(VI) exposure by downregulating and degrading Bcl-2 protein through the ubiquitin-proteasomal pathway. This study reveals a novel mechanism linking .O(-)(2) with Bcl-2 stability and provides a new dimension to ROS-mediated Bcl-2 downregulation and apoptosis induction."
1233648,Borthiry et al. 2008,Addition of DNA to Cr(VI) and cytochrome b5 containing proteoliposomes leads to generation of DNA strand breaks and Cr(III) complexes,"Chromium (Cr) is a cytotoxic metal that can be associated with a variety of types of DNA damage, including Cr-DNA adducts and strand breaks. Prior studies with purified human cytochrome b(5) and NADPH:P450 reductase in reconstituted proteoliposomes (PLs) demonstrated rapid reduction of Cr(VI) (hexavalent chromium, as CrO(4)(2-), and the generation of Cr(V), superoxide (O(2)(*-)), and hydroxyl radical (HO(*)). Studies reported here examined the potential for the species produced by this system to interact with DNA. Strand breaks of purified plasmid DNA increased over time aerobically, but were not observed in the absence of O(2). Cr(V) is formed under both conditions, so the breaks are not mediated directly by Cr(V). The aerobic strand breaks were significantly prevented by catalase and EtOH, but not by the metal chelator diethylenetriaminepentaacetic acid (DTPA), suggesting that they are largely due to HO(*) from Cr-mediated redox cycling. EPR was used to assess the formation of Cr-DNA complexes. Following a 10-min incubation of PLs, CrO(4)(2-), and plasmid DNA, intense EPR signals at g=5.7 and g=5.0 were observed. These signals are attributed to specific Cr(III) complexes with large zero field splitting (ZFS). Without DNA, the signals in the g=5 region were weak. The large ZFS signals were not seen, when Cr(III)Cl(3) was incubated with DNA, suggesting that the Cr(III)-DNA interactions are different when generated by the PLs. After 24 h, a broad signal at g=2 is attributed to Cr(III) complexes with a small ZFS. This g=2 signal was observed without DNA, but it was different from that seen with plasmid. It is concluded that EPR can detect specific Cr(III) complexes that depend on the presence of plasmid DNA and the manner in which the Cr(III) is formed.","Addition of DNA to Cr(VI) and cytochrome b5 containing proteoliposomes leads to generation of DNA strand breaks and Cr(III) complexes Abs: Chromium (Cr) is a cytotoxic metal that can be associated with a variety of types of DNA damage, including Cr-DNA adducts and strand breaks. Prior studies with purified human cytochrome b(5) and NADPH:P450 reductase in reconstituted proteoliposomes (PLs) demonstrated rapid reduction of Cr(VI) (hexavalent chromium, as CrO(4)(2-), and the generation of Cr(V), superoxide (O(2)(*-)), and hydroxyl radical (HO(*)). Studies reported here examined the potential for the species produced by this system to interact with DNA. Strand breaks of purified plasmid DNA increased over time aerobically, but were not observed in the absence of O(2). Cr(V) is formed under both conditions, so the breaks are not mediated directly by Cr(V). The aerobic strand breaks were significantly prevented by catalase and EtOH, but not by the metal chelator diethylenetriaminepentaacetic acid (DTPA), suggesting that they are largely due to HO(*) from Cr-mediated redox cycling. EPR was used to assess the formation of Cr-DNA complexes. Following a 10-min incubation of PLs, CrO(4)(2-), and plasmid DNA, intense EPR signals at g=5.7 and g=5.0 were observed. These signals are attributed to specific Cr(III) complexes with large zero field splitting (ZFS). Without DNA, the signals in the g=5 region were weak. The large ZFS signals were not seen, when Cr(III)Cl(3) was incubated with DNA, suggesting that the Cr(III)-DNA interactions are different when generated by the PLs. After 24 h, a broad signal at g=2 is attributed to Cr(III) complexes with a small ZFS. This g=2 signal was observed without DNA, but it was different from that seen with plasmid. It is concluded that EPR can detect specific Cr(III) complexes that depend on the presence of plasmid DNA and the manner in which the Cr(III) is formed."
1233645,Yu et al. 2008,Differences in uptake and translocation of hexavalent and trivalent chromium by two species of willows,"Uptake and translocation of chromium (Cr) by two willow species was investigated. Intact pre-rooted weeping willows (Salix babylonica L.) and hankow willows (Salix matsudana Koidz) were grown hydroponically and spiked with hexavalent chromium [Cr (VI)] or trivalent chromium [Cr (III)] at 25.0 +/- 0.5 degrees C for 120 h. Removal of leaves was also performed as a treatment to quantify the effect of transpiration on uptake and translocation of either of the Cr species. Although the two willow species were able to eliminate Cr (VI) and Cr (III) from the hydroponic solution, significant differences in the removal rate for both chemical species were observed between the two willows (p &lt; 0.05): faster removal rate for Cr (III) than Cr (VI) was detected in both willow species; hankow willows showed higher removal potential for both chemical species than weeping willows. Remarkable decreases in the removal rates for both Cr species were detected in the willows with leaves removed (p &lt; 0.05). The results from the treatments spiked with Cr (VI) also revealed that Cr was more mobile in plant materials of hankow willows than that in weeping willows (p &lt; 0.01), while higher translocation efficiency of Cr was observed in weeping willows than hankow willows for the Cr (III) treated (p &lt; 0.01). However, a convincing decrease in the translocation efficiency due to the removal of leaves was only observed in the treatments spiked with Cr (VI) (p &lt; 0.05). Substantial differences existed in the distribution of Cr species in plant materials after exposure of either of the chemical forms: roots and lower stems were the major sites for accumulation in weeping willows exposed to Cr (VI) and Cr (III), respectively; in contrast roots were the only sink in hankow willows exposed to both chemical species. The capacity of willows to assimilate both Cr species was also evaluated using detached leaves and roots of both willow species in sealed glass vessels in vivo. The results indicated that detached roots showed a more remarkable capacity to remove Cr (III) from the hydroponic solution than Cr (VI) (p &lt; 0.01). Although detached leaves of both willow species were able to efficiently eliminate Cr (III), neither of them reduced the concentration of Cr (VI) in the solution. The results suggests that different mechanisms for uptake, assimilation and translocation of Cr (VI) and Cr (III) exist in different willow species and phytoremediation of Cr should consider this factor for the proposed target effectively.","Differences in uptake and translocation of hexavalent and trivalent chromium by two species of willows Abs: Uptake and translocation of chromium (Cr) by two willow species was investigated. Intact pre-rooted weeping willows (Salix babylonica L.) and hankow willows (Salix matsudana Koidz) were grown hydroponically and spiked with hexavalent chromium [Cr (VI)] or trivalent chromium [Cr (III)] at 25.0 +/- 0.5 degrees C for 120 h. Removal of leaves was also performed as a treatment to quantify the effect of transpiration on uptake and translocation of either of the Cr species. Although the two willow species were able to eliminate Cr (VI) and Cr (III) from the hydroponic solution, significant differences in the removal rate for both chemical species were observed between the two willows (p &lt; 0.05): faster removal rate for Cr (III) than Cr (VI) was detected in both willow species; hankow willows showed higher removal potential for both chemical species than weeping willows. Remarkable decreases in the removal rates for both Cr species were detected in the willows with leaves removed (p &lt; 0.05). The results from the treatments spiked with Cr (VI) also revealed that Cr was more mobile in plant materials of hankow willows than that in weeping willows (p &lt; 0.01), while higher translocation efficiency of Cr was observed in weeping willows than hankow willows for the Cr (III) treated (p &lt; 0.01). However, a convincing decrease in the translocation efficiency due to the removal of leaves was only observed in the treatments spiked with Cr (VI) (p &lt; 0.05). Substantial differences existed in the distribution of Cr species in plant materials after exposure of either of the chemical forms: roots and lower stems were the major sites for accumulation in weeping willows exposed to Cr (VI) and Cr (III), respectively; in contrast roots were the only sink in hankow willows exposed to both chemical species. The capacity of willows to assimilate both Cr species was also evaluated using detached leaves and roots of both willow species in sealed glass vessels in vivo. The results indicated that detached roots showed a more remarkable capacity to remove Cr (III) from the hydroponic solution than Cr (VI) (p &lt; 0.01). Although detached leaves of both willow species were able to efficiently eliminate Cr (III), neither of them reduced the concentration of Cr (VI) in the solution. The results suggests that different mechanisms for uptake, assimilation and translocation of Cr (VI) and Cr (III) exist in different willow species and phytoremediation of Cr should consider this factor for the proposed target effectively."
1233644,Vanengelen et al. 2008,"Fe(III), Cr(VI), and Fe(III) mediated Cr(VI) reduction in alkaline media using a Halomonas isolate from Soap Lake, Washington","Hexavalent chromium is one of the most widely distributed environmental contaminants. Given the carcinogenic and mutagenic consequences of Cr(VI) exposure, the release of Cr(VI) into the environment has long been a major concern. While many reports of microbial Cr(VI) reduction are in circulation, very few have demonstrated Cr(VI) reduction under alkaline conditions. Since Cr(VI) exhibits higher mobility in alkaline soils relative to pH neutral soils, and since Cr contamination of alkaline soils is associated with a number of industrial activities, microbial Cr(VI) reduction under alkaline conditions requires attention.Soda lakes are the most stable alkaline environments on earth, and contain a wide diversity of alkaliphilic organisms. In this study, a bacterial isolate belonging to the Halomonas genus was obtained from Soap Lake, a chemically stratified alkaline lake located in central Washington State. The ability of this isolate to reduce Cr(VI) and Fe(III) was assessed under alkaline (pH = 9), anoxic, non-growth conditions with acetate as an electron donor. Metal reduction rates were quantified using Monod kinetics. In addition, Cr(VI) reduction experiments were carried out in the presence of Fe(III) to evaluate the possible enhancement of Cr(VI) reduction rates through electron shuttling mechanisms. While Fe(III) reduction rates were slow compared to previously reported rates, Cr(VI) reduction rates fell within range of previously reported rates.","Fe(III), Cr(VI), and Fe(III) mediated Cr(VI) reduction in alkaline media using a Halomonas isolate from Soap Lake, Washington Abs: Hexavalent chromium is one of the most widely distributed environmental contaminants. Given the carcinogenic and mutagenic consequences of Cr(VI) exposure, the release of Cr(VI) into the environment has long been a major concern. While many reports of microbial Cr(VI) reduction are in circulation, very few have demonstrated Cr(VI) reduction under alkaline conditions. Since Cr(VI) exhibits higher mobility in alkaline soils relative to pH neutral soils, and since Cr contamination of alkaline soils is associated with a number of industrial activities, microbial Cr(VI) reduction under alkaline conditions requires attention.Soda lakes are the most stable alkaline environments on earth, and contain a wide diversity of alkaliphilic organisms. In this study, a bacterial isolate belonging to the Halomonas genus was obtained from Soap Lake, a chemically stratified alkaline lake located in central Washington State. The ability of this isolate to reduce Cr(VI) and Fe(III) was assessed under alkaline (pH = 9), anoxic, non-growth conditions with acetate as an electron donor. Metal reduction rates were quantified using Monod kinetics. In addition, Cr(VI) reduction experiments were carried out in the presence of Fe(III) to evaluate the possible enhancement of Cr(VI) reduction rates through electron shuttling mechanisms. While Fe(III) reduction rates were slow compared to previously reported rates, Cr(VI) reduction rates fell within range of previously reported rates."
1233643,Kolomaznik et al. 2008,"Leather waste--potential threat to human health, and a new technology of its treatment","In this paper, the authors deal with the problem of processing various types of waste generated by leather industry, with special emphasis to chrome-tanned waste. The agent that makes this waste potentially hazardous is hexavalent chromium. Its compounds can have negative effects on human health and some CrVI salts are considered carcinogens. The authors present the risks of spontaneous oxidization of CrIII to CrVI in the open-air dumps as well as the possible risks of wearing bad quality shoes, in which the chromium content is not controlled. There are several ways of handling primary leather waste, but no satisfactory technology has been developed for the secondary waste (manipulation waste, e.g. leather scraps and used leather products). In this contribution, a new three-step hybrid technology of processing manipulation waste is presented and tested under laboratory, pilot-scale and industrial conditions. The filtrate can be used as a good quality NPK fertilizer. The solid product, titanium-chromium sludge, can serve as an inorganic pigment in glass and ceramic industry. Further, the authors propose selective collection of used leather products (e.g. old shoes), the hydrolysable parts of which can be also processed by the new hybrid technology.","Leather waste--potential threat to human health, and a new technology of its treatment Abs: In this paper, the authors deal with the problem of processing various types of waste generated by leather industry, with special emphasis to chrome-tanned waste. The agent that makes this waste potentially hazardous is hexavalent chromium. Its compounds can have negative effects on human health and some CrVI salts are considered carcinogens. The authors present the risks of spontaneous oxidization of CrIII to CrVI in the open-air dumps as well as the possible risks of wearing bad quality shoes, in which the chromium content is not controlled. There are several ways of handling primary leather waste, but no satisfactory technology has been developed for the secondary waste (manipulation waste, e.g. leather scraps and used leather products). In this contribution, a new three-step hybrid technology of processing manipulation waste is presented and tested under laboratory, pilot-scale and industrial conditions. The filtrate can be used as a good quality NPK fertilizer. The solid product, titanium-chromium sludge, can serve as an inorganic pigment in glass and ceramic industry. Further, the authors propose selective collection of used leather products (e.g. old shoes), the hydrolysable parts of which can be also processed by the new hybrid technology."
1233642,Mattagajasingh et al. 2008,Carcinogenic chromium(VI)-induced protein oxidation and lipid peroxidation: implications in DNA-protein crosslinking,"Hexavalent chromium [Cr(VI)] compounds are Group-I human carcinogens. Cr(VI)-induced DNA-protein crosslinks (DPCs) have been implicated in the mutagenic and carcinogenic effects of Cr(VI). Although multiple mechanisms have been suggested for Cr(VI)-induced DNA-protein crosslinking, the mechanism of formation of DNA-protein crosslinks is not well understood. In this study, we explored the hypothesis that Cr(VI)-induced DPCs could be formed via generation of protein carbonyls and malonaldehyde (MDA) through protein oxidation and lipid peroxidation, respectively. Treatment of human leukemic T-lymphocyte MOLT4 cells with potassium chromate induced the formation of protein carbonyls and DPCs within 2 h, but increased the level of MDA only after 4 h, in a dose-dependent manner. Chromate treatment of MOLT4 cell homogenates also resulted in increased formation of MDA and protein carbonyls in a dose-dependent manner. EPR spectrometry in combination with spin trapping techniques revealed that reaction of Cr(VI) with biological reductants such as NADPH, glutathione reductase or H(2)O(2) generates Cr(V) and (*)OH radicals. Pretreatment of cells with antioxidants such as alpha-tocopherol or Tiron inhibited chromate-induced increase in formation of protein carbonyls, MDA and DPCs, but pretreatment of cells with riboflavin or 3-aminotriazole, a catalase inhibitor, had the opposite effect. Our results, for the first time, demonstrate that Cr(VI) exposure increases the cellular level of protein carbonyls and that Cr(VI)-induced DPCs may be formed, at least in part, via generation of protein carbonyls.","Carcinogenic chromium(VI)-induced protein oxidation and lipid peroxidation: implications in DNA-protein crosslinking Abs: Hexavalent chromium [Cr(VI)] compounds are Group-I human carcinogens. Cr(VI)-induced DNA-protein crosslinks (DPCs) have been implicated in the mutagenic and carcinogenic effects of Cr(VI). Although multiple mechanisms have been suggested for Cr(VI)-induced DNA-protein crosslinking, the mechanism of formation of DNA-protein crosslinks is not well understood. In this study, we explored the hypothesis that Cr(VI)-induced DPCs could be formed via generation of protein carbonyls and malonaldehyde (MDA) through protein oxidation and lipid peroxidation, respectively. Treatment of human leukemic T-lymphocyte MOLT4 cells with potassium chromate induced the formation of protein carbonyls and DPCs within 2 h, but increased the level of MDA only after 4 h, in a dose-dependent manner. Chromate treatment of MOLT4 cell homogenates also resulted in increased formation of MDA and protein carbonyls in a dose-dependent manner. EPR spectrometry in combination with spin trapping techniques revealed that reaction of Cr(VI) with biological reductants such as NADPH, glutathione reductase or H(2)O(2) generates Cr(V) and (*)OH radicals. Pretreatment of cells with antioxidants such as alpha-tocopherol or Tiron inhibited chromate-induced increase in formation of protein carbonyls, MDA and DPCs, but pretreatment of cells with riboflavin or 3-aminotriazole, a catalase inhibitor, had the opposite effect. Our results, for the first time, demonstrate that Cr(VI) exposure increases the cellular level of protein carbonyls and that Cr(VI)-induced DPCs may be formed, at least in part, via generation of protein carbonyls."
1233640,Bansal et al. 2009,Removal of Cr(VI) from aqueous solutions using pre-consumer processing agricultural waste: a case study of rice husk,"This paper reports the feasibility of using pre-consumer processing agricultural waste to remove Cr(VI) from synthetic wastewater under different experimental conditions. For this, rice husk, has been used after pre-treatments (boiling and formaldehyde treatment). Effect of various process parameters, namely, pH, adsorbent dose, initial chromium concentration and contact time has been studied in batch systems. The removal of chromium was dependent on the physico-chemical characteristics of the adsorbent, adsorbate concentration and other studied process parameters. Maximum metal removal was observed at pH 2.0. The efficiencies of boiled and formaldehyde treated rice husk for Cr(VI) removal were 71.0% and 76.5% respectively for dilute solutions at 20gl(-1) adsorbent dose. The experimental data were analyzed using Freundlich, Langmuir and Dubinin-Radushkevich (D-R) isotherm models. It was found that Freundlich and D-R models fitted well. The results revealed that the hexavalent chromium is considerably adsorbed on rice husk and it could be an economical method for the removal of hexavalent chromium from aqueous systems. FTIR and SEM were recorded, before and after adsorption, to explore number and position of the functional groups available for Cr(VI) binding on to studied adsorbents and changes in adsorbent surface morphology.","Removal of Cr(VI) from aqueous solutions using pre-consumer processing agricultural waste: a case study of rice husk Abs: This paper reports the feasibility of using pre-consumer processing agricultural waste to remove Cr(VI) from synthetic wastewater under different experimental conditions. For this, rice husk, has been used after pre-treatments (boiling and formaldehyde treatment). Effect of various process parameters, namely, pH, adsorbent dose, initial chromium concentration and contact time has been studied in batch systems. The removal of chromium was dependent on the physico-chemical characteristics of the adsorbent, adsorbate concentration and other studied process parameters. Maximum metal removal was observed at pH 2.0. The efficiencies of boiled and formaldehyde treated rice husk for Cr(VI) removal were 71.0% and 76.5% respectively for dilute solutions at 20gl(-1) adsorbent dose. The experimental data were analyzed using Freundlich, Langmuir and Dubinin-Radushkevich (D-R) isotherm models. It was found that Freundlich and D-R models fitted well. The results revealed that the hexavalent chromium is considerably adsorbed on rice husk and it could be an economical method for the removal of hexavalent chromium from aqueous systems. FTIR and SEM were recorded, before and after adsorption, to explore number and position of the functional groups available for Cr(VI) binding on to studied adsorbents and changes in adsorbent surface morphology."
1233639,Nemr 2009,Potential of pomegranate husk carbon for Cr(VI) removal from wastewater: kinetic and isotherm studies,"Pomegranate husk was converted into activated carbon and tested for its ability to remove hexavalent chromium from wastewater. The new activated carbon was obtained from pomegranate husk by dehydration process using concentrated sulfuric acid. The important parameters for the adsorption process such as pH, metal concentration and sorbent weight were investigated. Batch equilibrium experiments exhibited that a maximum chromium uptake was obtained at pH 1.0. The maximum adsorption capacity for pomegranate husk activated carbon was 35.2mgg(-1) as calculated by Langmuir model. The ability of activated carbon to remove chromium from synthetic sea water, natural sea water and wastewater was investigated as well. Different isotherm models were used to analyze the experimental data and the models parameters were evaluated. This study showed that the removal of toxic chromium by activated carbon developed from pomegranate husk is a promising technique.","Potential of pomegranate husk carbon for Cr(VI) removal from wastewater: kinetic and isotherm studies Abs: Pomegranate husk was converted into activated carbon and tested for its ability to remove hexavalent chromium from wastewater. The new activated carbon was obtained from pomegranate husk by dehydration process using concentrated sulfuric acid. The important parameters for the adsorption process such as pH, metal concentration and sorbent weight were investigated. Batch equilibrium experiments exhibited that a maximum chromium uptake was obtained at pH 1.0. The maximum adsorption capacity for pomegranate husk activated carbon was 35.2mgg(-1) as calculated by Langmuir model. The ability of activated carbon to remove chromium from synthetic sea water, natural sea water and wastewater was investigated as well. Different isotherm models were used to analyze the experimental data and the models parameters were evaluated. This study showed that the removal of toxic chromium by activated carbon developed from pomegranate husk is a promising technique."
1233637,Kumar and  Chakraborty 2009,Fixed-bed column study for hexavalent chromium removal and recovery by short-chain polyaniline synthesized on jute fiber,"Fixed-bed column studies were conducted to evaluate performance of a short-chain polymer, polyaniline, synthesized on the surface of jute fiber (PANI-jute) for the removal of hexavalent chromium [Cr(VI)] in aqueous environment. Influent pH, column bed depth, influent Cr(VI) concentrations and influent flow rate were variable parameters for the present study. Optimum pH for total chromium removal was observed as 3 by electrostatic attraction of acid chromate ion (HCrO(4)(-)) with protonated amine group (NH(3)(+)) of PANI-jute. With increase in column bed depth from 40 to 60 cm, total chromium uptake by PANI-jute increased from 4.14 to 4.66 mg/g with subsequent increase in throughput volume from 9.84 to 12.6L at exhaustion point. The data obtained for total chromium removal were well described by BDST equation till 10% breakthrough. Adsorption rate constant and dynamic bed capacity at 10% breakthrough were observed as 0.01 L/mgh and 1069.46 mg/L, respectively. Adsorbed total chromium was recovered back from PANI-jute as non-toxic Cr(III) after ignition with more than 97% reduction in weight, minimizing the problem of solid waste disposal.","Fixed-bed column study for hexavalent chromium removal and recovery by short-chain polyaniline synthesized on jute fiber Abs: Fixed-bed column studies were conducted to evaluate performance of a short-chain polymer, polyaniline, synthesized on the surface of jute fiber (PANI-jute) for the removal of hexavalent chromium [Cr(VI)] in aqueous environment. Influent pH, column bed depth, influent Cr(VI) concentrations and influent flow rate were variable parameters for the present study. Optimum pH for total chromium removal was observed as 3 by electrostatic attraction of acid chromate ion (HCrO(4)(-)) with protonated amine group (NH(3)(+)) of PANI-jute. With increase in column bed depth from 40 to 60 cm, total chromium uptake by PANI-jute increased from 4.14 to 4.66 mg/g with subsequent increase in throughput volume from 9.84 to 12.6L at exhaustion point. The data obtained for total chromium removal were well described by BDST equation till 10% breakthrough. Adsorption rate constant and dynamic bed capacity at 10% breakthrough were observed as 0.01 L/mgh and 1069.46 mg/L, respectively. Adsorbed total chromium was recovered back from PANI-jute as non-toxic Cr(III) after ignition with more than 97% reduction in weight, minimizing the problem of solid waste disposal."
1233636,Hu et al. 2009,Removal of chromium from aqueous solution by using oxidized multiwalled carbon nanotubes,"The batch removal of hexavalent chromium (Cr(VI)) from aqueous solution by using oxidized multiwalled carbon nanotubes (MWCNTs) was studied under ambient conditions. The effect of pH, initial concentration of Cr(VI), MWCNT content, contact time and ionic strength on the removal of Cr(VI) was also investigated. The removal was favored at low pH with maximum removal at pH &lt;2. The adsorption kinetics was modeled by first-order reversible kinetics, pseudo-first-order kinetics, pseudo-second-order kinetics, and intraparticle diffusion models, respectively. The rate constants for all these kinetic models were calculated, and the results indicate that pseudo-second-order kinetics model was well suitable to model the kinetic adsorption of Cr(VI). The removal of chromium mainly depends on the occurrence of redox reaction of adsorbed Cr(VI) on the surface of oxidized MWCNTs to the formation of Cr(III), and subsequent the sorption of Cr(III) on MWCNTs appears as the leading mechanism for chromium uptake to MWCNTs. The presence of Cr(III) and Cr(VI) on oxidized MWCNTs was confirmed by the X-ray photoelectron spectroscopic analysis. The application of Langmuir and Freundlich isotherms are applied to fit the adsorption data of Cr(VI). Equilibrium data were well described by the typical Langmuir adsorption isotherm. Overall, the study demonstrated that MWCNTs can effectively remove Cr(VI) from aqueous solution under a wide range of experimental conditions, without significant Cr(III) release.","Removal of chromium from aqueous solution by using oxidized multiwalled carbon nanotubes Abs: The batch removal of hexavalent chromium (Cr(VI)) from aqueous solution by using oxidized multiwalled carbon nanotubes (MWCNTs) was studied under ambient conditions. The effect of pH, initial concentration of Cr(VI), MWCNT content, contact time and ionic strength on the removal of Cr(VI) was also investigated. The removal was favored at low pH with maximum removal at pH &lt;2. The adsorption kinetics was modeled by first-order reversible kinetics, pseudo-first-order kinetics, pseudo-second-order kinetics, and intraparticle diffusion models, respectively. The rate constants for all these kinetic models were calculated, and the results indicate that pseudo-second-order kinetics model was well suitable to model the kinetic adsorption of Cr(VI). The removal of chromium mainly depends on the occurrence of redox reaction of adsorbed Cr(VI) on the surface of oxidized MWCNTs to the formation of Cr(III), and subsequent the sorption of Cr(III) on MWCNTs appears as the leading mechanism for chromium uptake to MWCNTs. The presence of Cr(III) and Cr(VI) on oxidized MWCNTs was confirmed by the X-ray photoelectron spectroscopic analysis. The application of Langmuir and Freundlich isotherms are applied to fit the adsorption data of Cr(VI). Equilibrium data were well described by the typical Langmuir adsorption isotherm. Overall, the study demonstrated that MWCNTs can effectively remove Cr(VI) from aqueous solution under a wide range of experimental conditions, without significant Cr(III) release."
1233635,López-Luna et al. 2009,"Toxicity assessment of soil amended with tannery sludge, trivalent chromium and hexavalent chromium, using wheat, oat and sorghum plants","This work assessed the effect of soil amended with tannery sludge (0, 500, 1000, 2000, 4000 and 8000 mg Cr kg(-1)soil), Cr(3+) as CrCl(3).6H(2)O (0, 100, 250, 500, 1000 and 2000 mg Cr kg(-1)soil), and Cr(6+) as K(2)Cr(2)O(7) (0, 25, 50, 100, 200 and 500 mg Cr kg(-1)soil) on wheat, oat and sorghum plants. Seed germination, seedling growth (root and shoot) and Cr accumulation in dry tissue were measured. Toxicological parameters; medium effective concentration, no observed adverse effect concentration and low observed adverse effect concentration were determined. Root growth was the most sensitive assessment of Cr toxicity (P&lt;0.05). There was a significant correlation (P&lt;0.0001) between Cr accumulation in dry tissue and toxic effects on seedling growth. The three Cr sources had different accumulation and mobility patterns; tannery sludge was less toxic for all three plant species, followed by CrCl(3).6H(2)O and K(2)Cr(2)O(7).","Toxicity assessment of soil amended with tannery sludge, trivalent chromium and hexavalent chromium, using wheat, oat and sorghum plants Abs: This work assessed the effect of soil amended with tannery sludge (0, 500, 1000, 2000, 4000 and 8000 mg Cr kg(-1)soil), Cr(3+) as CrCl(3).6H(2)O (0, 100, 250, 500, 1000 and 2000 mg Cr kg(-1)soil), and Cr(6+) as K(2)Cr(2)O(7) (0, 25, 50, 100, 200 and 500 mg Cr kg(-1)soil) on wheat, oat and sorghum plants. Seed germination, seedling growth (root and shoot) and Cr accumulation in dry tissue were measured. Toxicological parameters; medium effective concentration, no observed adverse effect concentration and low observed adverse effect concentration were determined. Root growth was the most sensitive assessment of Cr toxicity (P&lt;0.05). There was a significant correlation (P&lt;0.0001) between Cr accumulation in dry tissue and toxic effects on seedling growth. The three Cr sources had different accumulation and mobility patterns; tannery sludge was less toxic for all three plant species, followed by CrCl(3).6H(2)O and K(2)Cr(2)O(7)."
1233634,Wise et al. 2009,Medaka (Oryzias latipes) as a sentinel species for aquatic animals: Medaka cells exhibit a similar genotoxic response as North Atlantic right whale cells,"Hexavalent chromium (Cr(VI)) is emerging as a major concern for aquatic environments, particularly marine environments. Medaka (Oryzias latipes) has been used as a model species for human and aquatic health, including the marine environment, though few studies have directly compared toxicological responses in medaka to humans or other aquatic species. We used a medaka fin cell line to compare the genotoxic response of medaka to Cr(VI) to the response observed in North Atlantic right whale cells to see if responses in medaka were similar to those of other aquatic species, particularly aquatic mammals. We used the production of chromosomal aberrations as a measure of genotoxicity. We found that in medaka cells, concentrations of 1, 5 and 10 microM sodium chromate damaged 17, 32 and 43% of metaphases, respectively and these same concentrations 1, 2.5, 5 and 10 microM sodium chromate damaged 14, 24 and 49% of metaphases, respectively, in North Atlantic right whale lung cells and 11, 32 and 41% of metaphases, respectively, in North Atlantic right whale testes cells. These data show that genotoxic responses in medaka are comparable to those seen in North Atlantic right whale cells, consistent with the hypothesis that medaka are a useful model for other aquatic species.","Medaka (Oryzias latipes) as a sentinel species for aquatic animals: Medaka cells exhibit a similar genotoxic response as North Atlantic right whale cells Abs: Hexavalent chromium (Cr(VI)) is emerging as a major concern for aquatic environments, particularly marine environments. Medaka (Oryzias latipes) has been used as a model species for human and aquatic health, including the marine environment, though few studies have directly compared toxicological responses in medaka to humans or other aquatic species. We used a medaka fin cell line to compare the genotoxic response of medaka to Cr(VI) to the response observed in North Atlantic right whale cells to see if responses in medaka were similar to those of other aquatic species, particularly aquatic mammals. We used the production of chromosomal aberrations as a measure of genotoxicity. We found that in medaka cells, concentrations of 1, 5 and 10 microM sodium chromate damaged 17, 32 and 43% of metaphases, respectively and these same concentrations 1, 2.5, 5 and 10 microM sodium chromate damaged 14, 24 and 49% of metaphases, respectively, in North Atlantic right whale lung cells and 11, 32 and 41% of metaphases, respectively, in North Atlantic right whale testes cells. These data show that genotoxic responses in medaka are comparable to those seen in North Atlantic right whale cells, consistent with the hypothesis that medaka are a useful model for other aquatic species."
1233633,Geier et al. 2009,Chromated metal products may be hazardous to patients with chromate allergy,"<strong>BACKGROUND: </strong>Hidden allergen exposure may contribute to persistence and relapse of chromate dermatitis. According to case reports, chromated metal products, such as screws, fittings, etc., may be relevant allergen sources for patients sensitized to chromate.<br /><br /><strong>OBJECTIVES: </strong>To examine concomitant patch test reactivity to potassium dichromate 0.5% petrolatum (pet.) and three different types of chromated metal rings.<br /><br /><strong>PATIENTS/METHODS: </strong>Patients with proven or suspected chromate allergy were patch tested with potassium dichromate 0.5% pet. and three different types of chromated metal rings (yellow, olive, and black). Hexavalent chromium Cr(VI) release from the patch tested rings was chemically analysed.<br /><br /><strong>RESULTS: </strong>Ninety-five patients were tested: 49/95 (52%) reacted to potassium dichromate and 25/95 (26%) reacted to black chromated rings. Reactions to chromated rings exclusively occurred in patients reacting to potassium dichromate. Of 20 patients with a strong reaction to potassium dichromate, 14 reacted to black chromated rings. These were shown to have a high Cr(VI) release. Only two patients reacted to the other chromated rings, which had a very low Cr(VI) release.<br /><br /><strong>CONCLUSIONS: </strong>Handling chromated metal products must be regarded a hazard to chromate-sensitive patients, in particular those with a strong sensitization.","Chromated metal products may be hazardous to patients with chromate allergy Abs: <strong>BACKGROUND: </strong>Hidden allergen exposure may contribute to persistence and relapse of chromate dermatitis. According to case reports, chromated metal products, such as screws, fittings, etc., may be relevant allergen sources for patients sensitized to chromate.<br /><br /><strong>OBJECTIVES: </strong>To examine concomitant patch test reactivity to potassium dichromate 0.5% petrolatum (pet.) and three different types of chromated metal rings.<br /><br /><strong>PATIENTS/METHODS: </strong>Patients with proven or suspected chromate allergy were patch tested with potassium dichromate 0.5% pet. and three different types of chromated metal rings (yellow, olive, and black). Hexavalent chromium Cr(VI) release from the patch tested rings was chemically analysed.<br /><br /><strong>RESULTS: </strong>Ninety-five patients were tested: 49/95 (52%) reacted to potassium dichromate and 25/95 (26%) reacted to black chromated rings. Reactions to chromated rings exclusively occurred in patients reacting to potassium dichromate. Of 20 patients with a strong reaction to potassium dichromate, 14 reacted to black chromated rings. These were shown to have a high Cr(VI) release. Only two patients reacted to the other chromated rings, which had a very low Cr(VI) release.<br /><br /><strong>CONCLUSIONS: </strong>Handling chromated metal products must be regarded a hazard to chromate-sensitive patients, in particular those with a strong sensitization."
1233632,Dubey and  Gopal 2009,Application of natural adsorbent from silver impregnated Arachis hypogaea based thereon in the processes of hexavalent chromium for the purification of water,"Different industries generate huge amounts of chromium, both in solid and liquid form which leached out and find their way to the aquifers. Here we report the removal of Cr(VI) by the silver impregnated activated carbon developed from agricultural waste material at pH 3 from drinking water. Result revealed that adsorption of chromium(VI) on silver impregnated groundnut husk carbon was endothermic in nature. Thermodynamic parameters such as the entropy change, enthalpy change and Gibbs free energy change were found to be 1.68 kJ mol(-1)K(-1), 0.46 kJ mol(-1) and -4.38 kJ mol(-1), respectively. The measured adsorption kinetics is well described by a pseudo first-order kinetic model. The effect of flow rate, column depth and initial concentration of chromium(VI) on the removal of chromium by the impregnated adsorbent is presented. Scanning Electron Microscope (SEM), Electron Dispersive X-ray Analysis (EDX) and FTIR analysis show that the silver is impregnated on the surface. Shifts in the FTIR spectra suggest that dichromate binding occurs with silver and other functional groups and that silver treated groundnut husk carbon removes chromium. The 96h static acute toxicity test was conducted to ensure the safe disposal of the used adsorbent.","Application of natural adsorbent from silver impregnated Arachis hypogaea based thereon in the processes of hexavalent chromium for the purification of water Abs: Different industries generate huge amounts of chromium, both in solid and liquid form which leached out and find their way to the aquifers. Here we report the removal of Cr(VI) by the silver impregnated activated carbon developed from agricultural waste material at pH 3 from drinking water. Result revealed that adsorption of chromium(VI) on silver impregnated groundnut husk carbon was endothermic in nature. Thermodynamic parameters such as the entropy change, enthalpy change and Gibbs free energy change were found to be 1.68 kJ mol(-1)K(-1), 0.46 kJ mol(-1) and -4.38 kJ mol(-1), respectively. The measured adsorption kinetics is well described by a pseudo first-order kinetic model. The effect of flow rate, column depth and initial concentration of chromium(VI) on the removal of chromium by the impregnated adsorbent is presented. Scanning Electron Microscope (SEM), Electron Dispersive X-ray Analysis (EDX) and FTIR analysis show that the silver is impregnated on the surface. Shifts in the FTIR spectra suggest that dichromate binding occurs with silver and other functional groups and that silver treated groundnut husk carbon removes chromium. The 96h static acute toxicity test was conducted to ensure the safe disposal of the used adsorbent."
1233631,Wei et al. 2009,Selective adsorption and separation of chromium (VI) on the magnetic iron-nickel oxide from waste nickel liquid,"The selective adsorption of Cr (VI) from the wastewater of Cr (VI)-Ni (II) by magnetically iron-nickel oxide was investigated in this study. Synthetic iron-nickel oxide magnetic particles in the co-sedimentation method were used as adsorbent to remove hexavalent chromium ions. The characteristic of adsorption was evaluated by Langmuir, Freundlich isotherm and Dubinin-Kaganer-Radushkevich (DKR) equations in the simulation wastewater of Cr (VI)-Ni (II) bi-system. The energy spectra and FT-IR analysis were used to test adsorbent before and after adsorption. The obtained results suggest that the uptake of chromium (VI) effect is obvious from phosphate anions and that from others is unobvious. The maximum adsorption capacity of hexavalent chromium is about 30 mg/g at pH 5.00+/-0.02, and it was reduced by increasing the total dissolved substance (TDS) of system. Adsorption energies E are about 10.310-21.321 kJ/mol which were obtained from DKR equation in difference TDS conditions. The regeneration shows that the iron-nickel oxide has good reuse performance and the hexavalent chromium was recycled. The major adsorption mechanism proposed was the ions exchange; however the surface coordination was a main role in the condition of TDS less than 200mg/L.","Selective adsorption and separation of chromium (VI) on the magnetic iron-nickel oxide from waste nickel liquid Abs: The selective adsorption of Cr (VI) from the wastewater of Cr (VI)-Ni (II) by magnetically iron-nickel oxide was investigated in this study. Synthetic iron-nickel oxide magnetic particles in the co-sedimentation method were used as adsorbent to remove hexavalent chromium ions. The characteristic of adsorption was evaluated by Langmuir, Freundlich isotherm and Dubinin-Kaganer-Radushkevich (DKR) equations in the simulation wastewater of Cr (VI)-Ni (II) bi-system. The energy spectra and FT-IR analysis were used to test adsorbent before and after adsorption. The obtained results suggest that the uptake of chromium (VI) effect is obvious from phosphate anions and that from others is unobvious. The maximum adsorption capacity of hexavalent chromium is about 30 mg/g at pH 5.00+/-0.02, and it was reduced by increasing the total dissolved substance (TDS) of system. Adsorption energies E are about 10.310-21.321 kJ/mol which were obtained from DKR equation in difference TDS conditions. The regeneration shows that the iron-nickel oxide has good reuse performance and the hexavalent chromium was recycled. The major adsorption mechanism proposed was the ions exchange; however the surface coordination was a main role in the condition of TDS less than 200mg/L."
1233630,Fahnestock et al. 2009,Selective detection of hexachromium ions by localized surface plasmon resonance measurements using gold nanoparticles/chitosan composite interfaces,"Selective removal of hexavalent chromium ions from aqueous solutions using a chitosan/gold nanoparticles composite film was demonstrated. Localized surface plasmon resonance (LSPR) was used to measure the interface stability and detect the incorporation of chromium ions over time. The effects of pH, ethylenediaminetetraacetic acid (EDTA), and various foreign ions such as trivalent chromium, sodium, calcium, phosphate, sulfate and chloride on the adsorption of hexavalent chromium were investigated.","Selective detection of hexachromium ions by localized surface plasmon resonance measurements using gold nanoparticles/chitosan composite interfaces Abs: Selective removal of hexavalent chromium ions from aqueous solutions using a chitosan/gold nanoparticles composite film was demonstrated. Localized surface plasmon resonance (LSPR) was used to measure the interface stability and detect the incorporation of chromium ions over time. The effects of pH, ethylenediaminetetraacetic acid (EDTA), and various foreign ions such as trivalent chromium, sodium, calcium, phosphate, sulfate and chloride on the adsorption of hexavalent chromium were investigated."
1233629,Nudler et al. 2009,Chromium VI administration induces oxidative stress in hypothalamus and anterior pituitary gland from male rats,"Hexavalent chromium (Cr VI)-containing compounds are known carcinogens which are present in industrial settings and in the environment. The major route of chromium exposure for the general population is oral intake. Previously we have observed that Cr VI affects anterior pituitary secretion and causes oxidative stress in vitro. The aim of the present work was to investigate if in vivo Cr VI treatment (100 ppm of Cr VI in drinking water for up 30 days) causes oxidative stress in hypothalamus and anterior pituitary gland from male rats. This treatment produced a 4-fold increase of chromium content in hypothalamus and 10-fold increase in anterior pituitary gland. Lipid peroxidation showed a significant increase in hypothalamus and anterior pituitary. Cr VI augmented superoxide dismutase activity in anterior pituitary gland and glutathione reductase activity in hypothalamus, but glutathione peroxidase and catalase activities remained unchanged in both tissues. Heme oxygenase-1 mRNA expression significantly rose in both tissues. Metallothionein 1 mRNA content increased in anterior pituitary and metallothionein 3 mRNA increased in hypothalamus. These results show, for the first time, that oral chronic administration of Cr VI produces oxidative stress on the hypothalamus and anterior pituitary gland which may affect normal endocrine function.","Chromium VI administration induces oxidative stress in hypothalamus and anterior pituitary gland from male rats Abs: Hexavalent chromium (Cr VI)-containing compounds are known carcinogens which are present in industrial settings and in the environment. The major route of chromium exposure for the general population is oral intake. Previously we have observed that Cr VI affects anterior pituitary secretion and causes oxidative stress in vitro. The aim of the present work was to investigate if in vivo Cr VI treatment (100 ppm of Cr VI in drinking water for up 30 days) causes oxidative stress in hypothalamus and anterior pituitary gland from male rats. This treatment produced a 4-fold increase of chromium content in hypothalamus and 10-fold increase in anterior pituitary gland. Lipid peroxidation showed a significant increase in hypothalamus and anterior pituitary. Cr VI augmented superoxide dismutase activity in anterior pituitary gland and glutathione reductase activity in hypothalamus, but glutathione peroxidase and catalase activities remained unchanged in both tissues. Heme oxygenase-1 mRNA expression significantly rose in both tissues. Metallothionein 1 mRNA content increased in anterior pituitary and metallothionein 3 mRNA increased in hypothalamus. These results show, for the first time, that oral chronic administration of Cr VI produces oxidative stress on the hypothalamus and anterior pituitary gland which may affect normal endocrine function."
1233628,Dai et al. 2009,Chromium reduces the in vitro activity and fidelity of DNA replication mediated by the human cell DNA synthesome,"Hexavalent chromium Cr(VI) is known to be a carcinogenic metal ion, with a complicated mechanism of action. It can be found within our environment in soil and water contaminated by manufacturing processes. Cr(VI) ion is readily taken up by cells, and is recognized to be both genotoxic and cytotoxic; following its reduction to the stable trivalent form of the ion, chromium(Cr(III)), within cells. This form of the ion is known to impede the activity of cellular DNA polymerase and polymerase-mediated DNA replication. Here, we report the effects of chromium on the activity and fidelity of the DNA replication process mediated by the human cell DNA synthesome. The DNA synthesome is a functional multiprotein complex that is fully competent to carry-out each phase of the DNA replication process. The IC(50) of Cr(III) toward the activity of DNA synthesome-associated DNA polymerases alpha, delta and epsilon is 15, 45 and 125 muM, respectively. Cr(III) inhibits synthesome-mediated DNA synthesis (IC(50)=88 muM), and significantly reduces the fidelity of synthesome-mediated DNA replication. The mutation frequency induced by the different concentrations of Cr(III) ion used in our assays ranges from 2-13 fold higher than that which occurs spontaneously, and the types of mutations include single nucleotide substitutions, insertions, and deletions. Single nucleotide substitutions are the predominant type of mutation, and they occur primarily at GC base-pairs. Cr(III) ion produces a lower number of transition and a higher number of transversion mutations than occur spontaneously. Unlike Cr(III), Cr(VI) ion has little effect on the in vitro DNA synthetic activity and fidelity of the DNA synthesome, but does significantly inhibit DNA synthesis in intact cells. Cell growth and proliferation is also arrested by increasing concentrations of Cr(VI) ion. Our studies provide evidence indicating that the chromium ion induced decrease in the fidelity and activity of synthesome mediated DNA replication correlates with the genotoxic and cytotoxic effects of this metal ion; and promotes cell killing via inhibition of the DNA polymerase activity mediating the DNA replication and repair processes utilized by human cells.","Chromium reduces the in vitro activity and fidelity of DNA replication mediated by the human cell DNA synthesome Abs: Hexavalent chromium Cr(VI) is known to be a carcinogenic metal ion, with a complicated mechanism of action. It can be found within our environment in soil and water contaminated by manufacturing processes. Cr(VI) ion is readily taken up by cells, and is recognized to be both genotoxic and cytotoxic; following its reduction to the stable trivalent form of the ion, chromium(Cr(III)), within cells. This form of the ion is known to impede the activity of cellular DNA polymerase and polymerase-mediated DNA replication. Here, we report the effects of chromium on the activity and fidelity of the DNA replication process mediated by the human cell DNA synthesome. The DNA synthesome is a functional multiprotein complex that is fully competent to carry-out each phase of the DNA replication process. The IC(50) of Cr(III) toward the activity of DNA synthesome-associated DNA polymerases alpha, delta and epsilon is 15, 45 and 125 muM, respectively. Cr(III) inhibits synthesome-mediated DNA synthesis (IC(50)=88 muM), and significantly reduces the fidelity of synthesome-mediated DNA replication. The mutation frequency induced by the different concentrations of Cr(III) ion used in our assays ranges from 2-13 fold higher than that which occurs spontaneously, and the types of mutations include single nucleotide substitutions, insertions, and deletions. Single nucleotide substitutions are the predominant type of mutation, and they occur primarily at GC base-pairs. Cr(III) ion produces a lower number of transition and a higher number of transversion mutations than occur spontaneously. Unlike Cr(III), Cr(VI) ion has little effect on the in vitro DNA synthetic activity and fidelity of the DNA synthesome, but does significantly inhibit DNA synthesis in intact cells. Cell growth and proliferation is also arrested by increasing concentrations of Cr(VI) ion. Our studies provide evidence indicating that the chromium ion induced decrease in the fidelity and activity of synthesome mediated DNA replication correlates with the genotoxic and cytotoxic effects of this metal ion; and promotes cell killing via inhibition of the DNA polymerase activity mediating the DNA replication and repair processes utilized by human cells."
1233627,Lin et al. 2009,Acute severe chromium poisoning after dermal exposure to hexavalent chromium,"Severe acute chromium poisoning related to dermal involvement has rarely been reported in the literature. We report a case of acute severe chromium poisoning through skin exposure as a result of a chemical burn of 15% of the body surface area and multiple organ failure after short-term exposure. Medical interventions, including mechanical ventilation, continuous venovenous hemofiltration, and plasmapheresis were performed. In addition, a chelating agent, dimercaptopropane sulfonic acid, was infused intravenously, combined with intravenous N-acetylcysteine and ascorbic acid as adjuvant therapy. The patient was discharged on day 33 without long-term sequelae. The consequence of transdermal exposure of hexavalent chromium should not be overlooked.","Acute severe chromium poisoning after dermal exposure to hexavalent chromium Abs: Severe acute chromium poisoning related to dermal involvement has rarely been reported in the literature. We report a case of acute severe chromium poisoning through skin exposure as a result of a chemical burn of 15% of the body surface area and multiple organ failure after short-term exposure. Medical interventions, including mechanical ventilation, continuous venovenous hemofiltration, and plasmapheresis were performed. In addition, a chelating agent, dimercaptopropane sulfonic acid, was infused intravenously, combined with intravenous N-acetylcysteine and ascorbic acid as adjuvant therapy. The patient was discharged on day 33 without long-term sequelae. The consequence of transdermal exposure of hexavalent chromium should not be overlooked."
1233624,Lushchak et al. 2009,Chromium(III) induces oxidative stress in goldfish liver and kidney,"In the environment chromium is found mainly in two valence states-hexavalent chromium (Cr6+) and trivalent chromium (Cr3+). The present study evaluates the effects of Cr3+ exposure on goldfish by analyzing parameters of oxidative stress and antioxidant defense in liver and kidney of fish given 96 h exposures to Cr3+ concentrations of 1, 2.5, 5 or 10 mg/l in aquarium water. Cr3+ exposure did not alter two parameters of oxidative stress-protein carbonyl content and lipid peroxide concentrations in either organ. However, Cr3+ exposure did decrease total glutathione concentration in liver by 34-69% and in kidney to 36-49% of the respective control values. Oxidized GSSG content fell by similar percentages so that the ratio [GSSG]/[total glutathione] remained constant at all Cr3+ exposure levels except in liver under the highest, 10 mg/l, exposure level. In liver, exposure to 1-5 mg/l Cr3+ led to a decrease in the activity of superoxide dismutase (SOD) by 29-36%, and at 10 mg/l Cr3+ the reduction was 54%, whereas in kidney approximately 30% reductions in SOD activity were seen at concentrations 1 and 10 mg/l Cr3+. Catalase activity was not significantly affected by 1-5 mg/l Cr3+, but was reduced by 57 and 42% in liver and kidney, respectively. Chromium exposure also reduced the activity of glutathione-S-transferase in both organs by 17-50% but did not affect glutathione reductase or glucose-6-phosphate dehydrogenase activities. A comparison of Cr3+ effects on goldfish liver and kidney metabolism indicates that the trivalent ion induces stronger oxidative stress than Cr6+ at the same concentrations.","Chromium(III) induces oxidative stress in goldfish liver and kidney Abs: In the environment chromium is found mainly in two valence states-hexavalent chromium (Cr6+) and trivalent chromium (Cr3+). The present study evaluates the effects of Cr3+ exposure on goldfish by analyzing parameters of oxidative stress and antioxidant defense in liver and kidney of fish given 96 h exposures to Cr3+ concentrations of 1, 2.5, 5 or 10 mg/l in aquarium water. Cr3+ exposure did not alter two parameters of oxidative stress-protein carbonyl content and lipid peroxide concentrations in either organ. However, Cr3+ exposure did decrease total glutathione concentration in liver by 34-69% and in kidney to 36-49% of the respective control values. Oxidized GSSG content fell by similar percentages so that the ratio [GSSG]/[total glutathione] remained constant at all Cr3+ exposure levels except in liver under the highest, 10 mg/l, exposure level. In liver, exposure to 1-5 mg/l Cr3+ led to a decrease in the activity of superoxide dismutase (SOD) by 29-36%, and at 10 mg/l Cr3+ the reduction was 54%, whereas in kidney approximately 30% reductions in SOD activity were seen at concentrations 1 and 10 mg/l Cr3+. Catalase activity was not significantly affected by 1-5 mg/l Cr3+, but was reduced by 57 and 42% in liver and kidney, respectively. Chromium exposure also reduced the activity of glutathione-S-transferase in both organs by 17-50% but did not affect glutathione reductase or glucose-6-phosphate dehydrogenase activities. A comparison of Cr3+ effects on goldfish liver and kidney metabolism indicates that the trivalent ion induces stronger oxidative stress than Cr6+ at the same concentrations."
1233623,Pillay et al. 2009,Multi-walled carbon nanotubes as adsorbents for the removal of parts per billion levels of hexavalent chromium from aqueous solution,"The adsorption capabilities for the removal of parts per billion levels (ppb) of hexavalent chromium by three adsorbents namely activated carbon, functionalized multi-walled carbon nanotubes (MWCNTs) and unfunctionalized multi-walled carbon nanotubes were investigated as a function of contact time, initial solution pH, initial Cr(VI) concentrations and the presence of competing anions. The unfunctionalized MWCNTs showed the highest adsorption capability with up to 98% of a 100 ppb Cr(VI) solution being adsorbed. Both functionalized and non-functionalized MWCNTs showed a superior adsorption capability to that of activated carbon. The removal of Cr(VI) was higher at lower pH. Furthermore, the uptake of Cr(VI) was hindered by the presence of the competing anions, Cl(-) and SO(4)(2-). Both Langmuir and Freundlich isotherms have been used to describe the Cr(VI) adsorption process. The major mechanisms for Cr(VI) removal have been identified as an ion exchange mechanism, intraparticle diffusion and electrostatic interactions. The adsorbed Cr(VI) could also be desorbed readily from the MWCNTs surface at high pH.","Multi-walled carbon nanotubes as adsorbents for the removal of parts per billion levels of hexavalent chromium from aqueous solution Abs: The adsorption capabilities for the removal of parts per billion levels (ppb) of hexavalent chromium by three adsorbents namely activated carbon, functionalized multi-walled carbon nanotubes (MWCNTs) and unfunctionalized multi-walled carbon nanotubes were investigated as a function of contact time, initial solution pH, initial Cr(VI) concentrations and the presence of competing anions. The unfunctionalized MWCNTs showed the highest adsorption capability with up to 98% of a 100 ppb Cr(VI) solution being adsorbed. Both functionalized and non-functionalized MWCNTs showed a superior adsorption capability to that of activated carbon. The removal of Cr(VI) was higher at lower pH. Furthermore, the uptake of Cr(VI) was hindered by the presence of the competing anions, Cl(-) and SO(4)(2-). Both Langmuir and Freundlich isotherms have been used to describe the Cr(VI) adsorption process. The major mechanisms for Cr(VI) removal have been identified as an ion exchange mechanism, intraparticle diffusion and electrostatic interactions. The adsorbed Cr(VI) could also be desorbed readily from the MWCNTs surface at high pH."
1233622,Yuan et al. 2009,Montmorillonite-supported magnetite nanoparticles for the removal of hexavalent chromium [Cr(VI)] from aqueous solutions,"Montmorillonite-supported magnetite nanoparticles were prepared by co-precipitation and hydrosol method. The obtained materials were characterized by X-ray diffraction, nitrogen adsorption, elemental analysis, differential scanning calorimetry, transmission electron microscopy and X-ray photoelectron spectroscopy. The average sizes of the magnetite nanoparticles without and with montmorillonite support are around 25 and 15 nm, respectively. The montmorillonite-supported magnetite nanoparticles exist on the surface or inside the interparticle pores of clays, with better dispersing and less coaggregation than the ones without montmorillonite support. Batch tests were carried out to investigate the removal mechanism of hexavalent chromium [Cr(VI)] by these synthesized magnetite nanoparticles. The Cr(VI) uptake was mainly governed by a physico-chemical process, which included an electrostatic attraction followed by a redox process in which Cr(VI) was reduced into trivalent chromium. The adsorption of Cr(VI) was highly pH-dependent and the kinetics of the adsorption followed the Pseudo-second-order model. The adsorption data of unsupported and clay-supported magnetite nanoparticles fit well with the Langmuir and Freundlich isotherm equations. The montmorillonite-supported magnetite nanoparticles showed a much better adsorption capacity per unit mass of magnetite (15.3mg/g) than unsupported magnetite (10.6 mg/g), and were more thermally stable than their unsupported counterparts. These fundamental results demonstrate that the montmorillonite-supported magnetite nanoparticles are readily prepared, enabling promising applications for the removal of Cr(VI) from aqueous solution.","Montmorillonite-supported magnetite nanoparticles for the removal of hexavalent chromium [Cr(VI)] from aqueous solutions Abs: Montmorillonite-supported magnetite nanoparticles were prepared by co-precipitation and hydrosol method. The obtained materials were characterized by X-ray diffraction, nitrogen adsorption, elemental analysis, differential scanning calorimetry, transmission electron microscopy and X-ray photoelectron spectroscopy. The average sizes of the magnetite nanoparticles without and with montmorillonite support are around 25 and 15 nm, respectively. The montmorillonite-supported magnetite nanoparticles exist on the surface or inside the interparticle pores of clays, with better dispersing and less coaggregation than the ones without montmorillonite support. Batch tests were carried out to investigate the removal mechanism of hexavalent chromium [Cr(VI)] by these synthesized magnetite nanoparticles. The Cr(VI) uptake was mainly governed by a physico-chemical process, which included an electrostatic attraction followed by a redox process in which Cr(VI) was reduced into trivalent chromium. The adsorption of Cr(VI) was highly pH-dependent and the kinetics of the adsorption followed the Pseudo-second-order model. The adsorption data of unsupported and clay-supported magnetite nanoparticles fit well with the Langmuir and Freundlich isotherm equations. The montmorillonite-supported magnetite nanoparticles showed a much better adsorption capacity per unit mass of magnetite (15.3mg/g) than unsupported magnetite (10.6 mg/g), and were more thermally stable than their unsupported counterparts. These fundamental results demonstrate that the montmorillonite-supported magnetite nanoparticles are readily prepared, enabling promising applications for the removal of Cr(VI) from aqueous solution."
1233621,Choi et al. 2009,Adsorption of Cr(VI) onto cationic surfactant-modified activated carbon,"Highly toxic oxyanions, such as hexavalent chromium (Cr(VI)), have caused adverse effects on human health. This study evaluated the feasibility of using cationic surfactant-modified activated carbon (AC) to remove Cr(VI). To modify activated carbon using a cationic surfactant, AC was mixed with a surfactant solution of 0.5 critical micelle concentration (CMC), at which concentration the surfactant molecules exist as mono-molecules. Adsorption kinetics and an isotherm model were used to study the adsorption characteristics of Cr(VI) onto MAC. The adsorption capacity of MAC for Cr(V) was enhanced compared to that of AC. MAC modified by hexadecyltrimethylammonium had a higher adsorption capacity for the removal of Cr(VI) than that modified by cetylpyridinium. The modification of AC by a cationic surfactant enhanced both its Cr(VI) adsorption rate and its Cr(VI) adsorption capacity. The breakthrough point of MAC for Cr(VI) was 100 times greater than for the raw AC. As a result, MAC is a promising adsorbent to treat Cr(VI) in an aqueous stream.","Adsorption of Cr(VI) onto cationic surfactant-modified activated carbon Abs: Highly toxic oxyanions, such as hexavalent chromium (Cr(VI)), have caused adverse effects on human health. This study evaluated the feasibility of using cationic surfactant-modified activated carbon (AC) to remove Cr(VI). To modify activated carbon using a cationic surfactant, AC was mixed with a surfactant solution of 0.5 critical micelle concentration (CMC), at which concentration the surfactant molecules exist as mono-molecules. Adsorption kinetics and an isotherm model were used to study the adsorption characteristics of Cr(VI) onto MAC. The adsorption capacity of MAC for Cr(V) was enhanced compared to that of AC. MAC modified by hexadecyltrimethylammonium had a higher adsorption capacity for the removal of Cr(VI) than that modified by cetylpyridinium. The modification of AC by a cationic surfactant enhanced both its Cr(VI) adsorption rate and its Cr(VI) adsorption capacity. The breakthrough point of MAC for Cr(VI) was 100 times greater than for the raw AC. As a result, MAC is a promising adsorbent to treat Cr(VI) in an aqueous stream."
1233620,Patlolla et al. 2009,"Potassium dichromate induced cytotoxicity, genotoxicity and oxidative stress in human liver carcinoma (HepG2) cells","Chromium is a widespread industrial waste. The soluble hexavalent chromium Cr (VI) is an environmental contaminant widely recognized to act as a carcinogen, mutagen and teratogen towards humans and animals. The fate of chromium in the environment is dependent on its oxidation state. Hexavalent chromium primarily enters the cells and undergoes metabolic reduction to trivalent chromium, resulting in the formation of reactive oxygen species together with oxidative tissue damage and a cascade of cellular events. However, the results from in vitro studies are often conflicting. The aim of this study was to develop a model to establish relationships between cytotoxicity, genotoxicity and oxidative stress, in human liver carcinoma [HepG2] cells exposed to potassium dichromate. HepG2 cells were cultured following standard protocols and exposed to various concentrations [0-50 microM] of potassium dichromate [K2Cr2O7]. Following exposure to the toxic metal, the MTT assay was performed to assess the cytotoxicity, the thiobarbituric acid test to evaluate the degree of lipid peroxidation as an indicator of oxidative stress and the alkaline comet assay was used to assess DNA damage to study genotoxicity. The results of the study indicated that potassium dichromate was cytotoxic to HepG2 cells. The LD(50) values of 8.83 +/- 0.89 microg/ml, 6.76 +/- 0.99 microg/ml, respectively, for cell mortality at 24 and 48 hrs were observed, indicating a dose- and time-dependent response with regard to the cytotoxic effects of potassium dichromate. A statistically significant increase in the concentration of malondialdehyde [MDA], an indicator of lipid peroxidation, was recorded in exposed cells [15.9 - 69.9 microM] compared to control [13 microM]. Similarly, a strong dose-response relationship (p&lt;0.05) was also obtained with respect to potassium dichromate induced DNA damage (comet assay) in HepG2 cells exposed [3.16 +/- 0.70 - 24.84 +/- 1.86 microns - mean comet tail length]; [12.4 +/- 1.45% - 76 +/- 1.49%-% tail DNA] to potassium dichromate than control [3.07 +/- 0.26 microns--mean comet tail length]; [2.69 + 0.19%-% Tail DNA], respectively. The results demonstrated that potassium dichromate was highly cytotoxic to HepG2 cells, and its cytotoxicity seems to be mediated by oxidative stress and DNA damage.","Potassium dichromate induced cytotoxicity, genotoxicity and oxidative stress in human liver carcinoma (HepG2) cells Abs: Chromium is a widespread industrial waste. The soluble hexavalent chromium Cr (VI) is an environmental contaminant widely recognized to act as a carcinogen, mutagen and teratogen towards humans and animals. The fate of chromium in the environment is dependent on its oxidation state. Hexavalent chromium primarily enters the cells and undergoes metabolic reduction to trivalent chromium, resulting in the formation of reactive oxygen species together with oxidative tissue damage and a cascade of cellular events. However, the results from in vitro studies are often conflicting. The aim of this study was to develop a model to establish relationships between cytotoxicity, genotoxicity and oxidative stress, in human liver carcinoma [HepG2] cells exposed to potassium dichromate. HepG2 cells were cultured following standard protocols and exposed to various concentrations [0-50 microM] of potassium dichromate [K2Cr2O7]. Following exposure to the toxic metal, the MTT assay was performed to assess the cytotoxicity, the thiobarbituric acid test to evaluate the degree of lipid peroxidation as an indicator of oxidative stress and the alkaline comet assay was used to assess DNA damage to study genotoxicity. The results of the study indicated that potassium dichromate was cytotoxic to HepG2 cells. The LD(50) values of 8.83 +/- 0.89 microg/ml, 6.76 +/- 0.99 microg/ml, respectively, for cell mortality at 24 and 48 hrs were observed, indicating a dose- and time-dependent response with regard to the cytotoxic effects of potassium dichromate. A statistically significant increase in the concentration of malondialdehyde [MDA], an indicator of lipid peroxidation, was recorded in exposed cells [15.9 - 69.9 microM] compared to control [13 microM]. Similarly, a strong dose-response relationship (p&lt;0.05) was also obtained with respect to potassium dichromate induced DNA damage (comet assay) in HepG2 cells exposed [3.16 +/- 0.70 - 24.84 +/- 1.86 microns - mean comet tail length]; [12.4 +/- 1.45% - 76 +/- 1.49%-% tail DNA] to potassium dichromate than control [3.07 +/- 0.26 microns--mean comet tail length]; [2.69 + 0.19%-% Tail DNA], respectively. The results demonstrated that potassium dichromate was highly cytotoxic to HepG2 cells, and its cytotoxicity seems to be mediated by oxidative stress and DNA damage."
1233619,Rivero-Huguet and  Marshall 2009,Reduction of hexavalent chromium mediated by micron- and nano-scale zero-valent metallic particles,"A variety of zero-valent metals (Al(0), Cu(0), Fe(0), Mg(0), Ni(0), Si(0) and Zn(0)), and Cu(0) and Fe(0) nano-sized particles were evaluated for reactivity towards the reduction of Cr(VI) in a surfactant preparation (Tween 20) under a selection of reaction conditions. At circum neutral pHs, a rapid inactivation of the surface was observed for almost all of the tested metals and complete reduction of Cr(VI) was achieved at acidic pH only by using Cu(0), Fe(0), Mg(0) or Zn(0). A considerable increase in reactivity (up to 100-fold) was observed for reductive remediation with nano-sized particles. The use of a solid support as a dispersant and stabilizer circumvented the tendency of freshly prepared nano-particles to either react with surrounding media or agglomerate, resulting in the formation of much larger flocs and appreciable loss in reactivity. The formation of clusters by polymeric structures provided an extra protection of the nano-particle surface with a striking improvement in their reactivity mainly at more alkaline conditions. Therefore the incorporation of an innocuous stabilizer can substantially enhance the stability of nano-particles for environmental transformations.","Reduction of hexavalent chromium mediated by micron- and nano-scale zero-valent metallic particles Abs: A variety of zero-valent metals (Al(0), Cu(0), Fe(0), Mg(0), Ni(0), Si(0) and Zn(0)), and Cu(0) and Fe(0) nano-sized particles were evaluated for reactivity towards the reduction of Cr(VI) in a surfactant preparation (Tween 20) under a selection of reaction conditions. At circum neutral pHs, a rapid inactivation of the surface was observed for almost all of the tested metals and complete reduction of Cr(VI) was achieved at acidic pH only by using Cu(0), Fe(0), Mg(0) or Zn(0). A considerable increase in reactivity (up to 100-fold) was observed for reductive remediation with nano-sized particles. The use of a solid support as a dispersant and stabilizer circumvented the tendency of freshly prepared nano-particles to either react with surrounding media or agglomerate, resulting in the formation of much larger flocs and appreciable loss in reactivity. The formation of clusters by polymeric structures provided an extra protection of the nano-particle surface with a striking improvement in their reactivity mainly at more alkaline conditions. Therefore the incorporation of an innocuous stabilizer can substantially enhance the stability of nano-particles for environmental transformations."
1233617,De Lucca et al. 2009,Effect of different doses of hexavalent chromium on mandibular growth and tooth eruption in juvenile Wistar rats,"Not only workers employed at industrial plants are exposed to intoxication with the element they manipulate, the population at large is also at risk of suffering health problems caused by contaminating wastes inadequately treated for their safe disposal. As a result certain toxic substances, such as hexavalent chromium,has reached the general population including children. The present study sought to evaluate the effect of intoxication with hexavalent chromium on body and mandibular growth and tooth eruption in suckling Wistar rats. Potassium dichromate was administered by gavage in a dose of 6.25 or 12.5mg/kg body weight (b.w.) to one of the two groups of 4-day-old Wistar rats during 10 days. Our results showed that the effects of chromium are dose-dependent. Morphometric studies of body growth showed lower body weight in both experimental groups and shorter tail length in animals receiving 12.5mg/kg b.w. dose of chromium, compared with controls. All parameters of mandibular growth were lower in the experimental group receiving 12.5mg/kg b.w. of chromium. Differences in tooth eruption were observed at the level of the first molar in animals receiving 12.5mg/kg and of the second molar in those receiving 6.25mg/kg b.w. of chromium. Chromium was found to affect all the studied parameters.","Effect of different doses of hexavalent chromium on mandibular growth and tooth eruption in juvenile Wistar rats Abs: Not only workers employed at industrial plants are exposed to intoxication with the element they manipulate, the population at large is also at risk of suffering health problems caused by contaminating wastes inadequately treated for their safe disposal. As a result certain toxic substances, such as hexavalent chromium,has reached the general population including children. The present study sought to evaluate the effect of intoxication with hexavalent chromium on body and mandibular growth and tooth eruption in suckling Wistar rats. Potassium dichromate was administered by gavage in a dose of 6.25 or 12.5mg/kg body weight (b.w.) to one of the two groups of 4-day-old Wistar rats during 10 days. Our results showed that the effects of chromium are dose-dependent. Morphometric studies of body growth showed lower body weight in both experimental groups and shorter tail length in animals receiving 12.5mg/kg b.w. dose of chromium, compared with controls. All parameters of mandibular growth were lower in the experimental group receiving 12.5mg/kg b.w. of chromium. Differences in tooth eruption were observed at the level of the first molar in animals receiving 12.5mg/kg and of the second molar in those receiving 6.25mg/kg b.w. of chromium. Chromium was found to affect all the studied parameters."
1233616,Nemec and  Barchowsky 2009,Signal transducer and activator of transcription 1 (STAT1) is essential for chromium silencing of gene induction in human airway epithelial cells,"Hexavalent chromium (Cr(VI)) promotes lung injury and pulmonary diseases through poorly defined mechanisms that may involve the silencing of inducible protective genes. The current study investigated the hypothesis that Cr(VI) actively signals through a signal transducer and activator of transcription 1 (STAT1)-dependent pathway to silence nickel (Ni)-induced expression of vascular endothelial cell growth factor A (VEGFA), an important mediator of lung injury and repair. In human bronchial airway epithelial (BEAS-2B) cells, Ni-induced VEGFA transcription by stimulating an extracellular regulated kinase (ERK) signaling cascade that involved Src kinase-activated Sp1 transactivation, as well as increased hypoxia-inducible factor-1 alpha (HIF-1 alpha) stabilization and DNA binding. Ni-stimulated ERK, Src, and HIF-1 alpha activities, as well as Ni-induced VEGFA transcript levels were inhibited in Cr(VI)-exposed cells. We previously demonstrated that Cr(VI) stimulates STAT1 to suppress VEGFA expression. In BEAS-2B cells stably expressing STAT1 short hairpin RNA, Cr(VI) increased VEGFA transcript levels and Sp1 transactivation. Moreover, in the absence of STAT1, Cr(VI), and Ni coexposures positively interacted to further increase VEGFA transcripts. This study demonstrates that metal-stimulated signaling cascades interact to regulate transcription and induction of adaptive or repair responses in airway cells. In addition, the data implicate STAT1 as a rate limiting mediator of Cr(VI)-stimulated gene regulation and suggest that cells lacking STAT1, such as many tumor cell lines, have opposite responses to Cr(VI) relative to normal cells.","Signal transducer and activator of transcription 1 (STAT1) is essential for chromium silencing of gene induction in human airway epithelial cells Abs: Hexavalent chromium (Cr(VI)) promotes lung injury and pulmonary diseases through poorly defined mechanisms that may involve the silencing of inducible protective genes. The current study investigated the hypothesis that Cr(VI) actively signals through a signal transducer and activator of transcription 1 (STAT1)-dependent pathway to silence nickel (Ni)-induced expression of vascular endothelial cell growth factor A (VEGFA), an important mediator of lung injury and repair. In human bronchial airway epithelial (BEAS-2B) cells, Ni-induced VEGFA transcription by stimulating an extracellular regulated kinase (ERK) signaling cascade that involved Src kinase-activated Sp1 transactivation, as well as increased hypoxia-inducible factor-1 alpha (HIF-1 alpha) stabilization and DNA binding. Ni-stimulated ERK, Src, and HIF-1 alpha activities, as well as Ni-induced VEGFA transcript levels were inhibited in Cr(VI)-exposed cells. We previously demonstrated that Cr(VI) stimulates STAT1 to suppress VEGFA expression. In BEAS-2B cells stably expressing STAT1 short hairpin RNA, Cr(VI) increased VEGFA transcript levels and Sp1 transactivation. Moreover, in the absence of STAT1, Cr(VI), and Ni coexposures positively interacted to further increase VEGFA transcripts. This study demonstrates that metal-stimulated signaling cascades interact to regulate transcription and induction of adaptive or repair responses in airway cells. In addition, the data implicate STAT1 as a rate limiting mediator of Cr(VI)-stimulated gene regulation and suggest that cells lacking STAT1, such as many tumor cell lines, have opposite responses to Cr(VI) relative to normal cells."
1233615,Caravelli and  Zaritzky 2009,About the performance of Sphaerotilus natans to reduce hexavalent chromium in batch and continuous reactors,"The hexavalent chromium biological reduction constitutes a safe and economical detoxification procedure of wastewaters containing Cr(VI). However, little research has been done to evaluate Cr(VI) tolerance and reduction capacity of microbial cultures under different growth conditions. The aims of this work were (a) to evaluate the capacity of Sphaerotilus natans to reduce Cr(VI) to Cr(III) in a continuous system limited in carbon and energy source or in nitrogen source, (b) to evaluate the toxic effect of Cr(VI) on this microorganism, (c) to carry out a complete analysis of Cr(VI) reduction by S. natans not only in continuous regime but also in batch system, and (d) to model the obtained results mathematically. S. natans exhibited great resistance to Cr(VI) (19-78 mg l(-1)) and optimal growth in continuous and batch systems using a mineral medium supplemented only with citric acid as organic substrate. In carbon- and energy-limited continuous systems, a maximum percentual decrease in Cr(VI) by 13% was reached for low influent Cr(VI) concentration (4.3-5.32 mg Cr(VI)l(-1)); the efficiency of the process did not notoriously increase as the length of cellular residence time was increased from 4.16 to 50h. A nitrogen-limited continuous operation with a cellular residence time of 28.5h resulted in a Cr(VI) decrease of approximately 26-32%. In batch system, a mathematical model allowed to predict the Cr(VI) concentration as a function of time and the ratio between the initial Cr(VI) concentration and that of the biomass. High concentrations of initial Cr(VI) and biomass produced the highest performance of the process of Cr(VI) reduction reached in batch system, aspects which should be considered in detoxification strategies of wastewaters.","About the performance of Sphaerotilus natans to reduce hexavalent chromium in batch and continuous reactors Abs: The hexavalent chromium biological reduction constitutes a safe and economical detoxification procedure of wastewaters containing Cr(VI). However, little research has been done to evaluate Cr(VI) tolerance and reduction capacity of microbial cultures under different growth conditions. The aims of this work were (a) to evaluate the capacity of Sphaerotilus natans to reduce Cr(VI) to Cr(III) in a continuous system limited in carbon and energy source or in nitrogen source, (b) to evaluate the toxic effect of Cr(VI) on this microorganism, (c) to carry out a complete analysis of Cr(VI) reduction by S. natans not only in continuous regime but also in batch system, and (d) to model the obtained results mathematically. S. natans exhibited great resistance to Cr(VI) (19-78 mg l(-1)) and optimal growth in continuous and batch systems using a mineral medium supplemented only with citric acid as organic substrate. In carbon- and energy-limited continuous systems, a maximum percentual decrease in Cr(VI) by 13% was reached for low influent Cr(VI) concentration (4.3-5.32 mg Cr(VI)l(-1)); the efficiency of the process did not notoriously increase as the length of cellular residence time was increased from 4.16 to 50h. A nitrogen-limited continuous operation with a cellular residence time of 28.5h resulted in a Cr(VI) decrease of approximately 26-32%. In batch system, a mathematical model allowed to predict the Cr(VI) concentration as a function of time and the ratio between the initial Cr(VI) concentration and that of the biomass. High concentrations of initial Cr(VI) and biomass produced the highest performance of the process of Cr(VI) reduction reached in batch system, aspects which should be considered in detoxification strategies of wastewaters."
1233614,Wang et al. 2009,Reactive oxygen species-induced cell death of rat primary astrocytes through mitochondria-mediated mechanism,"Astrocytes, the most abundant glial cell population in the central nervous system (CNS), play physiological roles in neuronal activities. Oxidative insult induced by the injury to the CNS causes neural cell death through extrinsic and intrinsic pathways. This study reports that reactive oxygen species (ROS) generated by exposure to the strong oxidizing agent, hexavalent chromium (Cr(VI)) as a chemical-induced oxidative stress model, caused astrocytes to undergo an apoptosis-like cell death through a caspase-3-independent mechanism. Although activating protein-1 (AP-1) and NF-kappaB were activated in Cr(VI)-primed astrocytes, the inhibition of their activity failed to increase astrocytic cell survival. The results further indicated that the reduction in mitochondrial membrane potential (MMP) was accompanied by an increase in the levels of ROS in Cr(VI)-primed astrocytes. Moreover, pretreatment of astrocytes with N-acetylcysteine (NAC), the potent ROS scavenger, attenuated ROS production and MMP loss in Cr(VI)-primed astrocytes, and significantly increased the survival of astrocytes, implying that the elevated ROS disrupted the mitochondrial function to result in the reduction of astrocytic cell viability. In addition, the nuclear expression of apoptosis-inducing factor (AIF) and endonuclease G (EndoG) was observed in Cr(VI)-primed astrocytes. Taken together, evidence shows that astrocytic cell death occurs by ROS-induced oxidative insult through a caspase-3-independent apoptotic mechanism involving the loss of MMP and an increase in the nuclear levels of mitochondrial pro-apoptosis proteins (AIF/EndoG). This mitochondria-mediated but caspase-3-independent apoptotic pathway may be involved in oxidative stress-induced astrocytic cell death in the injured CNS.","Reactive oxygen species-induced cell death of rat primary astrocytes through mitochondria-mediated mechanism Abs: Astrocytes, the most abundant glial cell population in the central nervous system (CNS), play physiological roles in neuronal activities. Oxidative insult induced by the injury to the CNS causes neural cell death through extrinsic and intrinsic pathways. This study reports that reactive oxygen species (ROS) generated by exposure to the strong oxidizing agent, hexavalent chromium (Cr(VI)) as a chemical-induced oxidative stress model, caused astrocytes to undergo an apoptosis-like cell death through a caspase-3-independent mechanism. Although activating protein-1 (AP-1) and NF-kappaB were activated in Cr(VI)-primed astrocytes, the inhibition of their activity failed to increase astrocytic cell survival. The results further indicated that the reduction in mitochondrial membrane potential (MMP) was accompanied by an increase in the levels of ROS in Cr(VI)-primed astrocytes. Moreover, pretreatment of astrocytes with N-acetylcysteine (NAC), the potent ROS scavenger, attenuated ROS production and MMP loss in Cr(VI)-primed astrocytes, and significantly increased the survival of astrocytes, implying that the elevated ROS disrupted the mitochondrial function to result in the reduction of astrocytic cell viability. In addition, the nuclear expression of apoptosis-inducing factor (AIF) and endonuclease G (EndoG) was observed in Cr(VI)-primed astrocytes. Taken together, evidence shows that astrocytic cell death occurs by ROS-induced oxidative insult through a caspase-3-independent apoptotic mechanism involving the loss of MMP and an increase in the nuclear levels of mitochondrial pro-apoptosis proteins (AIF/EndoG). This mitochondria-mediated but caspase-3-independent apoptotic pathway may be involved in oxidative stress-induced astrocytic cell death in the injured CNS."
1233613,Liu et al. 2009,The Werner syndrome protein functions in repair of Cr(VI)-induced replication-associated DNA damage,"Werner syndrome is a premature aging disorder characterized by cancer predisposition that is caused by loss of the Werner syndrome protein (WRN) helicase/exonuclease DNA repair protein. Hexavalent chromium is an environmental carcinogen and genotoxicant that is associated with respiratory cancers and induces several forms of DNA damage, including lesions that interfere with DNA replication. Based on the evidence that WRN protein facilitates repair of stalled and collapsed replication forks, we hypothesized that WRN functions in the cellular response to and recovery from Cr(VI)-induced genotoxicity and genomic instability. Here we report that human cells deficient in WRN protein are hypersensitive to Cr(VI) toxicity, and exhibit a delayed reduction in DNA breaks and stalled replication forks, indicated by gammaH2AX foci, during recovery from Cr(VI) exposure. Cr(VI)-induced WRN protein translocation from the nucleoli into nucleoplasmic foci in S-phase cells, and these foci colocalized with gammaH2AX foci indicating WRN responds to replication-associated DNA damage. As further evidence that Cr(VI) triggers stalled DNA replication, we observed Cr(VI) treatment induced an accumulation of cells in S-phase that exhibited high levels of gammaH2AX foci. Therefore, these data demonstrate a novel role for WRN protein in cellular protection against the environmental genotoxicant Cr(VI) and further provide evidence that Cr(VI) induces DNA replicative stress which has implications for aging and cancer.","The Werner syndrome protein functions in repair of Cr(VI)-induced replication-associated DNA damage Abs: Werner syndrome is a premature aging disorder characterized by cancer predisposition that is caused by loss of the Werner syndrome protein (WRN) helicase/exonuclease DNA repair protein. Hexavalent chromium is an environmental carcinogen and genotoxicant that is associated with respiratory cancers and induces several forms of DNA damage, including lesions that interfere with DNA replication. Based on the evidence that WRN protein facilitates repair of stalled and collapsed replication forks, we hypothesized that WRN functions in the cellular response to and recovery from Cr(VI)-induced genotoxicity and genomic instability. Here we report that human cells deficient in WRN protein are hypersensitive to Cr(VI) toxicity, and exhibit a delayed reduction in DNA breaks and stalled replication forks, indicated by gammaH2AX foci, during recovery from Cr(VI) exposure. Cr(VI)-induced WRN protein translocation from the nucleoli into nucleoplasmic foci in S-phase cells, and these foci colocalized with gammaH2AX foci indicating WRN responds to replication-associated DNA damage. As further evidence that Cr(VI) triggers stalled DNA replication, we observed Cr(VI) treatment induced an accumulation of cells in S-phase that exhibited high levels of gammaH2AX foci. Therefore, these data demonstrate a novel role for WRN protein in cellular protection against the environmental genotoxicant Cr(VI) and further provide evidence that Cr(VI) induces DNA replicative stress which has implications for aging and cancer."
1233612,Mishra and  Mohanty 2009,"Chronic exposure to sublethal hexavalent chromium affects organ histopathology and serum cortisol profile of a teleost, Channa punctatus (Bloch)","Effects of chronic exposures (one and two months) to sublethal doses of hexavalent chromium (2 and 4 mg/L potassium dichromate) on organ histopathology and serum cortisol profile were investigated and their overall impact on growth and behavior of a teleost fish, Channa punctatus was elucidated. Histopathological lesions were distinct in the vital organs gill, kidney and liver. The gill lamellae became lifted, fused, and showed oedema. Hyperplasia and hypertrophy of lamellar epithelial cells were distinct with desquamation. Hypertrophy of epithelial cells of renal tubules and reduction in tubular lumens were observed in the trunk kidney. The atrophy of the head kidney interrenal cells and decreased serum cortisol level indicated exhaustion of interrenal activity. Hepatocyte vacuolization and shrinkage, nuclear pyknosis and increase of sinusoidal spaces were observed in the liver. Abnormal behavioral patterns and reduced growth rate were also noticed in the exposed fish. The chronic hexavalent chromium exposure thus by affecting histopathology of gill, kidney (including interrenal tissue) and liver could impair the vital functions of respiration, excretion, metabolic regulation and maintenance of stress homeostasis which in the long-run may pose serious threat to fish health and affect their population.","Chronic exposure to sublethal hexavalent chromium affects organ histopathology and serum cortisol profile of a teleost, Channa punctatus (Bloch) Abs: Effects of chronic exposures (one and two months) to sublethal doses of hexavalent chromium (2 and 4 mg/L potassium dichromate) on organ histopathology and serum cortisol profile were investigated and their overall impact on growth and behavior of a teleost fish, Channa punctatus was elucidated. Histopathological lesions were distinct in the vital organs gill, kidney and liver. The gill lamellae became lifted, fused, and showed oedema. Hyperplasia and hypertrophy of lamellar epithelial cells were distinct with desquamation. Hypertrophy of epithelial cells of renal tubules and reduction in tubular lumens were observed in the trunk kidney. The atrophy of the head kidney interrenal cells and decreased serum cortisol level indicated exhaustion of interrenal activity. Hepatocyte vacuolization and shrinkage, nuclear pyknosis and increase of sinusoidal spaces were observed in the liver. Abnormal behavioral patterns and reduced growth rate were also noticed in the exposed fish. The chronic hexavalent chromium exposure thus by affecting histopathology of gill, kidney (including interrenal tissue) and liver could impair the vital functions of respiration, excretion, metabolic regulation and maintenance of stress homeostasis which in the long-run may pose serious threat to fish health and affect their population."
1233611,Geng et al. 2009,Preparation of chitosan-stabilized Fe(0) nanoparticles for removal of hexavalent chromium in water,"Chitosan-stabilized Fe(0) nanoparticles (CTO-Fe(0)) and Fe(0) nanoparticles synthesized in ethanol-water mixed system (EW-Fe(0)) were tested for reduction of Cr(VI) in water. Fourier transform infrared (FTIR) study suggested that nitrogen and oxygen atoms are the binding sites for chitosan on iron which was accountable for the stability of Fe(0) nanoparticles. While the EW-Fe(0) ignites spontaneously when exposed to air, the CTO-Fe(0) was still in zero valence state after exposure to air over 2-month period as shown by X-ray powder diffraction patterns. Batch experiments demonstrated that the maximum Cr(VI) reduction rates for CTO-Fe(0) was about 3 times higher than EW-Fe(0). Characterizations with high-resolution X-ray photoelectron spectroscopy (HR-XPS) revealed that Cr(VI) was reduced to Cr(III) and Fe(III) was the only component present on the Fe(0) nanoparticles surface. Additionally, chitosan can inhibited the formation of Fe(III)-Cr(III) precipitation due to its high ability to chelate Fe(III) which resulted in k(obs) for CTO-Fe(0) was about 1-3 times higher than EW-Fe(0). Due to the fast reaction kinetics and good stability against oxidation in air, the chitosan-stabilized Fe(0) nanoparticles have the potential to become an effective agent for in situ subsurface environment remediation.","Preparation of chitosan-stabilized Fe(0) nanoparticles for removal of hexavalent chromium in water Abs: Chitosan-stabilized Fe(0) nanoparticles (CTO-Fe(0)) and Fe(0) nanoparticles synthesized in ethanol-water mixed system (EW-Fe(0)) were tested for reduction of Cr(VI) in water. Fourier transform infrared (FTIR) study suggested that nitrogen and oxygen atoms are the binding sites for chitosan on iron which was accountable for the stability of Fe(0) nanoparticles. While the EW-Fe(0) ignites spontaneously when exposed to air, the CTO-Fe(0) was still in zero valence state after exposure to air over 2-month period as shown by X-ray powder diffraction patterns. Batch experiments demonstrated that the maximum Cr(VI) reduction rates for CTO-Fe(0) was about 3 times higher than EW-Fe(0). Characterizations with high-resolution X-ray photoelectron spectroscopy (HR-XPS) revealed that Cr(VI) was reduced to Cr(III) and Fe(III) was the only component present on the Fe(0) nanoparticles surface. Additionally, chitosan can inhibited the formation of Fe(III)-Cr(III) precipitation due to its high ability to chelate Fe(III) which resulted in k(obs) for CTO-Fe(0) was about 1-3 times higher than EW-Fe(0). Due to the fast reaction kinetics and good stability against oxidation in air, the chitosan-stabilized Fe(0) nanoparticles have the potential to become an effective agent for in situ subsurface environment remediation."
1233610,Espinoza-Quiñones et al. 2009,Root uptake and reduction of hexavalent chromium by aquatic macrophytes as assessed by high-resolution X-ray emission,"Aquatic macrophytes Salvinia auriculata, Pistia stratiotes and Eichhornia crassipes were chosen to investigate the Cr(VI) reduced by root-based biosorption in a chromium uptake experiment, using a high-resolution XRF technique. These plants were grown in hydroponics medium supplied with non-toxic Cr concentrations during a 27-day metal uptake experiment. The high-resolution Cr-Kbeta fluorescence spectra for dried root tissues and Cr reference material (100% Cr, Cr(2)O(3), and CrO(3)) were measured using an XRF spectrometer. For all species of aquatic plant treated with Cr(VI), the energy of the Cr-Kbeta(2,5) line was shifted around 8 eV below the same spectral line identified for the Cr(VI) reference, but it was also near to the line identified for the Cr(III) reference. Moreover, there was a lack of the strong Cr-Kbeta'' line assigned to the Cr(VI) reference material within the Cr(VI)-treated plant spectra, suggesting the reduction of Cr(VI) for other less toxic oxidation states of Cr. As all Cr-Kbeta spectra of root tissue species were compared, the peak energies and lineshape patterns of the Cr-Kbeta(2,5) line are coincident for the same aquatic plant species, when they were treated with Cr(III) and Cr(VI). Based on the experimental evidence, the Cr(VI) reduction process has happened during metal biosorption by these plants.","Root uptake and reduction of hexavalent chromium by aquatic macrophytes as assessed by high-resolution X-ray emission Abs: Aquatic macrophytes Salvinia auriculata, Pistia stratiotes and Eichhornia crassipes were chosen to investigate the Cr(VI) reduced by root-based biosorption in a chromium uptake experiment, using a high-resolution XRF technique. These plants were grown in hydroponics medium supplied with non-toxic Cr concentrations during a 27-day metal uptake experiment. The high-resolution Cr-Kbeta fluorescence spectra for dried root tissues and Cr reference material (100% Cr, Cr(2)O(3), and CrO(3)) were measured using an XRF spectrometer. For all species of aquatic plant treated with Cr(VI), the energy of the Cr-Kbeta(2,5) line was shifted around 8 eV below the same spectral line identified for the Cr(VI) reference, but it was also near to the line identified for the Cr(III) reference. Moreover, there was a lack of the strong Cr-Kbeta'' line assigned to the Cr(VI) reference material within the Cr(VI)-treated plant spectra, suggesting the reduction of Cr(VI) for other less toxic oxidation states of Cr. As all Cr-Kbeta spectra of root tissue species were compared, the peak energies and lineshape patterns of the Cr-Kbeta(2,5) line are coincident for the same aquatic plant species, when they were treated with Cr(III) and Cr(VI). Based on the experimental evidence, the Cr(VI) reduction process has happened during metal biosorption by these plants."
1233609,Parveen et al. 2009,Pycnogenol prevents potassium dichromate K2Cr2O7-induced oxidative damage and nephrotoxicity in rats,"Environmental and occupational exposure to chromium compounds, especially hexavalent chromium [Cr(VI)], is widely recognized as a potential nephrotoxic in humans and animals. Its toxicity is associated with overproduction of free radicals, which induces oxidative damage. Recent evidence indicates that Pycnogenol (PYC), French maritime pine bark extract, exhibits antioxidant potential and protects against various oxidative stressors. The aim of the present study was to examine the modulating impacts of PYC on potassium dichromate K2Cr2O7-induced oxidative damage and nephrotoxicity in rats. Male Wistar rats were divided into four groups. The first group was control, the second group was control plus pre-treated with PYC (10 mg/kg, body weight; in saline; intraperitoneally; once daily for 3 weeks) as drug control and the third group was saline pre-treated plus treated with a single injection of K2Cr2O7 (15 mg/kg, body weight; in saline; intraperitoneally) as toxicant group. The fourth group was PYC pre-treated plus K2Cr2O7 injected. Forty-eight hours after K2Cr2O7-treatment, blood was drawn for estimation of renal injury markers in serum. Rats were then sacrificed, and their kidneys were dissected for biochemical and histopathological assays. K2Cr2O7-treated rats showed significant increases in markers of renal injury in serum, including blood urea nitrogen (BUN), serum creatinine (Scr), and alkaline phosphatase (ALP), which were significantly (P &lt; 0.05) decreased by PYC pre-treatment. Moreover, prophylactic pre-treatment of rats with PYC significantly (P &lt; 0.05) ameliorated increased thiobarbituric reactive substances (TBARS), malonaldehyde (MDA) and protein carbonyl (PC), and decreased levels of glutathione (GSH) and catalase activity in the kidney homogenate of K2Cr2O7-treated rats. These results were also supported and confirmed with histopathological findings. The study suggests that PYC is effective in preventing K2Cr2O7-induced oxidative mediated nephrotoxicity, but more studies are needed to confirm the effects of PYC as a nephroprotective agent.","Pycnogenol prevents potassium dichromate K2Cr2O7-induced oxidative damage and nephrotoxicity in rats Abs: Environmental and occupational exposure to chromium compounds, especially hexavalent chromium [Cr(VI)], is widely recognized as a potential nephrotoxic in humans and animals. Its toxicity is associated with overproduction of free radicals, which induces oxidative damage. Recent evidence indicates that Pycnogenol (PYC), French maritime pine bark extract, exhibits antioxidant potential and protects against various oxidative stressors. The aim of the present study was to examine the modulating impacts of PYC on potassium dichromate K2Cr2O7-induced oxidative damage and nephrotoxicity in rats. Male Wistar rats were divided into four groups. The first group was control, the second group was control plus pre-treated with PYC (10 mg/kg, body weight; in saline; intraperitoneally; once daily for 3 weeks) as drug control and the third group was saline pre-treated plus treated with a single injection of K2Cr2O7 (15 mg/kg, body weight; in saline; intraperitoneally) as toxicant group. The fourth group was PYC pre-treated plus K2Cr2O7 injected. Forty-eight hours after K2Cr2O7-treatment, blood was drawn for estimation of renal injury markers in serum. Rats were then sacrificed, and their kidneys were dissected for biochemical and histopathological assays. K2Cr2O7-treated rats showed significant increases in markers of renal injury in serum, including blood urea nitrogen (BUN), serum creatinine (Scr), and alkaline phosphatase (ALP), which were significantly (P &lt; 0.05) decreased by PYC pre-treatment. Moreover, prophylactic pre-treatment of rats with PYC significantly (P &lt; 0.05) ameliorated increased thiobarbituric reactive substances (TBARS), malonaldehyde (MDA) and protein carbonyl (PC), and decreased levels of glutathione (GSH) and catalase activity in the kidney homogenate of K2Cr2O7-treated rats. These results were also supported and confirmed with histopathological findings. The study suggests that PYC is effective in preventing K2Cr2O7-induced oxidative mediated nephrotoxicity, but more studies are needed to confirm the effects of PYC as a nephroprotective agent."
1233607,Sánchez-Fortún et al. 2009,Toxicity and adaptation of Dictyosphaerium chlorelloides to extreme chromium contamination,"Metals are often spilled by industries into inland water environments, with adverse consequences. Numerous papers have reported that heavy metals produce massive destruction of algae. Nevertheless, algal populations seem to become tolerant when they have had previous exposures to heavy metals. Because the mechanisms allowing heavy metal tolerance of algae are not yet known, the present study analyzed the effect of hexavalent chromium on growth and photosynthetic performance of Dictyosphaerium chlorelloides, stressing on the adaptation mechanisms to chromium contamination. Growth and photosynthetic performance of algal cells were inhibited by Cr(VI) at 10 mg/L, and the 72-h median inhibition concentration was established as 1.64 and 1.54 mg/L, respectively. However, after further incubation for a three month period in an environment with 25 mg/L of chromium, some rare, chromium-resistant cells occasionally were found. A Luria-Delbrück fluctuation analysis was performed to distinguish between resistant algae arising from rare, spontaneous mutations and resistant algae arising from physiological adaptation and other adaptive mechanisms. Resistant cells arose only by spontaneous mutations before the addition of chromium, with a rate of 1.77 x 10(-6) mutants per cell division. From a practical point of view, the use of both chromium-sensitive and chromium-resistant genotypes could make possible a specific algal biosensor for chromium.","Toxicity and adaptation of Dictyosphaerium chlorelloides to extreme chromium contamination Abs: Metals are often spilled by industries into inland water environments, with adverse consequences. Numerous papers have reported that heavy metals produce massive destruction of algae. Nevertheless, algal populations seem to become tolerant when they have had previous exposures to heavy metals. Because the mechanisms allowing heavy metal tolerance of algae are not yet known, the present study analyzed the effect of hexavalent chromium on growth and photosynthetic performance of Dictyosphaerium chlorelloides, stressing on the adaptation mechanisms to chromium contamination. Growth and photosynthetic performance of algal cells were inhibited by Cr(VI) at 10 mg/L, and the 72-h median inhibition concentration was established as 1.64 and 1.54 mg/L, respectively. However, after further incubation for a three month period in an environment with 25 mg/L of chromium, some rare, chromium-resistant cells occasionally were found. A Luria-Delbrück fluctuation analysis was performed to distinguish between resistant algae arising from rare, spontaneous mutations and resistant algae arising from physiological adaptation and other adaptive mechanisms. Resistant cells arose only by spontaneous mutations before the addition of chromium, with a rate of 1.77 x 10(-6) mutants per cell division. From a practical point of view, the use of both chromium-sensitive and chromium-resistant genotypes could make possible a specific algal biosensor for chromium."
1233606,Narvekar and  Vaidya 2009,Role of functional groups on Aspergillus niger biomass in the detoxification of hexavalent chromium,"Chromium (VI) contamination is not uncommon, especially near industries involved in leather tanning, chrome painting, metal cleaning and processing, wood preservation and alloy preparation. The mutagenic and carcinogenic properties of Chromium (VI) necessitate effective remedial processes. Difficulties associated with chemical and physical techniques to remediate a Chromium (VI) contaminated site to EPA recommended level (50 ppm), in addition to higher costs involved, assert the need for bioremedial measures. Biosorption can be one such solution to clean up heavy metal contamination. The objective of this study was to examine the main aspects of a possible strategy for the removal of Chromium (VI), employing Aspergillus niger biomass. The roles played by amines, carboxylic acids, phosphates, in Chromium (VI) biosorption were studied. Amino and the carboxy groups on the fungal cell wall play an important role in sorption. However, the role of carboxy group was far less than amino group. Surface adsorption of Chromium (VI) was also seen by scanning electron microscopy (SEM) thus indicating involvement of ion-exchange and surface adsorption mechanism in removal of Chromium (VI) ions.","Role of functional groups on Aspergillus niger biomass in the detoxification of hexavalent chromium Abs: Chromium (VI) contamination is not uncommon, especially near industries involved in leather tanning, chrome painting, metal cleaning and processing, wood preservation and alloy preparation. The mutagenic and carcinogenic properties of Chromium (VI) necessitate effective remedial processes. Difficulties associated with chemical and physical techniques to remediate a Chromium (VI) contaminated site to EPA recommended level (50 ppm), in addition to higher costs involved, assert the need for bioremedial measures. Biosorption can be one such solution to clean up heavy metal contamination. The objective of this study was to examine the main aspects of a possible strategy for the removal of Chromium (VI), employing Aspergillus niger biomass. The roles played by amines, carboxylic acids, phosphates, in Chromium (VI) biosorption were studied. Amino and the carboxy groups on the fungal cell wall play an important role in sorption. However, the role of carboxy group was far less than amino group. Surface adsorption of Chromium (VI) was also seen by scanning electron microscopy (SEM) thus indicating involvement of ion-exchange and surface adsorption mechanism in removal of Chromium (VI) ions."
1233604,Graham and  Bouwer 2010,Rates of hexavalent chromium reduction in anoxic estuarine sediments: pH effects and the role of acid volatile sulfides,"Rates of Cr(VI) reduction were assessed in batch kinetic experiments using dilute suspensions of anoxic sediments collected from the Baltimore Harbor. Rapid and complete Cr(VI) reduction occurred on the time scale of minutes (pseudo-first-order rate constants ranged from 0.01 to 0.40 min(-1) for 1.0 g/L sediment suspensions at pH 7.0) via reaction with mineral surfaces. The reaction rate was first-order with respect to Cr(VI) concentration and proportional to the concentration of sediment acid volatile sulfides (AVS). AVS-normalized rates of Cr(VI) reduction decreased by approximately 2 orders of magnitude as the suspension pH increased from 5.0 to 8.2. The AVS-normalized rate constant was linearly correlated with the fraction of total dissolved Cr(VI) in the protonated HCrO(4)(-) form at a given pH (f(HCrO(4))((-))). The following rate law was found to describe all the experimental data: d[Cr(VI)]/dt = -k[AVS]f(HCrO(4))((-))[Cr(VI)](T), where the AVS- and pH-independent rate constant k = 3.14(+/-0.75) x 10(4) M(-1) min(-1). The results of this study suggest the importance of reactions between Cr(VI) and solid phase AVS constituents in controlling Cr(VI) fate in anoxic estuarine sediments, and indicate that Cr(VI) is unlikely to be a toxicological stressor in AVS-containing sediments.","Rates of hexavalent chromium reduction in anoxic estuarine sediments: pH effects and the role of acid volatile sulfides Abs: Rates of Cr(VI) reduction were assessed in batch kinetic experiments using dilute suspensions of anoxic sediments collected from the Baltimore Harbor. Rapid and complete Cr(VI) reduction occurred on the time scale of minutes (pseudo-first-order rate constants ranged from 0.01 to 0.40 min(-1) for 1.0 g/L sediment suspensions at pH 7.0) via reaction with mineral surfaces. The reaction rate was first-order with respect to Cr(VI) concentration and proportional to the concentration of sediment acid volatile sulfides (AVS). AVS-normalized rates of Cr(VI) reduction decreased by approximately 2 orders of magnitude as the suspension pH increased from 5.0 to 8.2. The AVS-normalized rate constant was linearly correlated with the fraction of total dissolved Cr(VI) in the protonated HCrO(4)(-) form at a given pH (f(HCrO(4))((-))). The following rate law was found to describe all the experimental data: d[Cr(VI)]/dt = -k[AVS]f(HCrO(4))((-))[Cr(VI)](T), where the AVS- and pH-independent rate constant k = 3.14(+/-0.75) x 10(4) M(-1) min(-1). The results of this study suggest the importance of reactions between Cr(VI) and solid phase AVS constituents in controlling Cr(VI) fate in anoxic estuarine sediments, and indicate that Cr(VI) is unlikely to be a toxicological stressor in AVS-containing sediments."
1233603,Clément et al. 2010,Effects of a physico-chemical treatment of a dredged sediment on its ecotoxicity after discharge in laboratory gravel pit microcosms,"In France, dredged sediments may be dumped into submerged gravel pits. As a consequence, adverse effects may be expected. In addition, groundwater quality may be impacted due to hydraulic communications with gravel pits. The immersion of dredged sediments into gravel pits should thus be restricted to clean or slightly contaminated sediments to minimize the impacts on aquatic ecosystems and human safe. For highly contaminated sediments, alternatives may be treatments aiming at removing or/and neutralizing contaminants. The Novosol treatment was aimed at neutralizing metals by complexation with orthophosphoric acid and discarding organic pollutants by calcination. The efficiency of the Novosol treatment was assessed in a scenario of sediment immersion into experimental laboratory gravel pits (LGP). A 180L water compartment was set up in each system so as to simulate the gravel pit, and various living organisms were introduced. Following a period of colonization and stabilization, raw and treated sediments were introduced into two different LGPs, and the fate and effects of pollutants were studied during the period of deposition and post-deposition. The treatment had positive effects on survival and development of benthic populations and reproduction of pond snails but the introduction of the treated sediment was followed by an increase in salinity (phosphates, sulphates) and a peak of hexavalent chromium at concentrations above drinkability limits and likely to have impaired invertebrate populations of the water column. The results of this study suggest that discharge of contaminated sediments at a high solid:liquid ratio (1:10) in gravel pits or equivalent aquatic ecosystems may have only limited effects on biota and ground water quality. The Novosol treatment should, however, be improved so as to increase efficiency of oxidised chromium complexation during the phosphatation step.","Effects of a physico-chemical treatment of a dredged sediment on its ecotoxicity after discharge in laboratory gravel pit microcosms Abs: In France, dredged sediments may be dumped into submerged gravel pits. As a consequence, adverse effects may be expected. In addition, groundwater quality may be impacted due to hydraulic communications with gravel pits. The immersion of dredged sediments into gravel pits should thus be restricted to clean or slightly contaminated sediments to minimize the impacts on aquatic ecosystems and human safe. For highly contaminated sediments, alternatives may be treatments aiming at removing or/and neutralizing contaminants. The Novosol treatment was aimed at neutralizing metals by complexation with orthophosphoric acid and discarding organic pollutants by calcination. The efficiency of the Novosol treatment was assessed in a scenario of sediment immersion into experimental laboratory gravel pits (LGP). A 180L water compartment was set up in each system so as to simulate the gravel pit, and various living organisms were introduced. Following a period of colonization and stabilization, raw and treated sediments were introduced into two different LGPs, and the fate and effects of pollutants were studied during the period of deposition and post-deposition. The treatment had positive effects on survival and development of benthic populations and reproduction of pond snails but the introduction of the treated sediment was followed by an increase in salinity (phosphates, sulphates) and a peak of hexavalent chromium at concentrations above drinkability limits and likely to have impaired invertebrate populations of the water column. The results of this study suggest that discharge of contaminated sediments at a high solid:liquid ratio (1:10) in gravel pits or equivalent aquatic ecosystems may have only limited effects on biota and ground water quality. The Novosol treatment should, however, be improved so as to increase efficiency of oxidised chromium complexation during the phosphatation step."
1233602,Soares et al. 2010,Chromium speciation analysis in bread samples,"Chromium is a controversial element with important essentiality and toxicity, depending on its different species; its speciation analysis in principal human foodstuffs, as in the case of bread, is of utmost importance. With this purpose, a method was validated, including a wet acid digestion procedure for total chromium dissolution, a selective alkaline extraction of hexavalent chromium, and ETAAS determination. The method was applied to the determination of total and hexavalent chromium in 152 bread samples. The total chromium contents were 47.3 +/- 20.0 and 50.9 +/- 22.2 microg/kg of dry weight for white and whole bread samples, respectively; those for hexavalent chromium were 5.65 +/- 5.44 and 6.82 +/- 4.88 microg/kg of dry weight. On the basis of a mean daily ingestion of three bread units, the calculated daily intake was up to 12.7 microg/day for total chromium and 1.98 microg/day for hexavalent chromium. Referring to total chromium, bread can contribute up to 10% of the Reference Daily Intake, 120 microg/day.","Chromium speciation analysis in bread samples Abs: Chromium is a controversial element with important essentiality and toxicity, depending on its different species; its speciation analysis in principal human foodstuffs, as in the case of bread, is of utmost importance. With this purpose, a method was validated, including a wet acid digestion procedure for total chromium dissolution, a selective alkaline extraction of hexavalent chromium, and ETAAS determination. The method was applied to the determination of total and hexavalent chromium in 152 bread samples. The total chromium contents were 47.3 +/- 20.0 and 50.9 +/- 22.2 microg/kg of dry weight for white and whole bread samples, respectively; those for hexavalent chromium were 5.65 +/- 5.44 and 6.82 +/- 4.88 microg/kg of dry weight. On the basis of a mean daily ingestion of three bread units, the calculated daily intake was up to 12.7 microg/day for total chromium and 1.98 microg/day for hexavalent chromium. Referring to total chromium, bread can contribute up to 10% of the Reference Daily Intake, 120 microg/day."
1233601,Wang et al. 2010,Apoptotic-related protein changes induced by hexavalent chromium in mice liver,"Although it has been reported that hexavalent chromium (Cr(VI)) could induce apoptosis in a variety of cell types, the molecular mechanisms underlying this process is still largely unknown. This study was undertaken to determine effects of single oral 0, 25, 50, and 100 mg/kg body weight doses of potassium dichromate on the expression level of p53, Bcl-2, Bax, cytochrome c, and caspase-3, which are vital regulators of apoptosis, in mice liver. The results showed that Cr(VI) could upregulate the protein expression of p53, Bax, cytochrome c, and caspase-3 and downregulate the expression of Bcl-2 in mice liver. All these results suggested that p53, Bcl-2, Bax, cytochrome c, and caspase-3 may be involved in the regulation of Cr(VI) induced apoptosis in vivo.","Apoptotic-related protein changes induced by hexavalent chromium in mice liver Abs: Although it has been reported that hexavalent chromium (Cr(VI)) could induce apoptosis in a variety of cell types, the molecular mechanisms underlying this process is still largely unknown. This study was undertaken to determine effects of single oral 0, 25, 50, and 100 mg/kg body weight doses of potassium dichromate on the expression level of p53, Bcl-2, Bax, cytochrome c, and caspase-3, which are vital regulators of apoptosis, in mice liver. The results showed that Cr(VI) could upregulate the protein expression of p53, Bax, cytochrome c, and caspase-3 and downregulate the expression of Bcl-2 in mice liver. All these results suggested that p53, Bcl-2, Bax, cytochrome c, and caspase-3 may be involved in the regulation of Cr(VI) induced apoptosis in vivo."
1233600,Iwasaki et al. 2010,Comparison of population-level effects of heavy metals on fathead minnow (Pimephales promelas),"To evaluate the population-level effects of heavy metals (copper, zinc, cadmium, hexavalent chromium, nickel) on fathead minnow, Pimephales promelas, we first estimated the concentration-effect relationships between the metal concentrations and individual traits (juvenile survivability, hatchability, fertility) by using toxicity data collected from the literature. A Leslie matrix model of fathead minnow was used to calculate population growth rates from these relationships. The population threshold concentrations (PTCs) leading to zero net growth of the fish population were as follows: Cu, 27.4; Cd, 33.2; Zn (soft water), 81.5; Zn (hard water), 85.8; Ni, 504.8; Cr, 3251.6 (microg L(-1)). By comparing the PTCs with no observed effect concentrations (NOECs), we found that some PTCs were equivalent to or even lower than the corresponding NOECs. This result suggests that current ecological risk assessments based on the NOECs can be inadequate for protecting aquatic populations and more efforts on the population-level studies are needed.","Comparison of population-level effects of heavy metals on fathead minnow (Pimephales promelas) Abs: To evaluate the population-level effects of heavy metals (copper, zinc, cadmium, hexavalent chromium, nickel) on fathead minnow, Pimephales promelas, we first estimated the concentration-effect relationships between the metal concentrations and individual traits (juvenile survivability, hatchability, fertility) by using toxicity data collected from the literature. A Leslie matrix model of fathead minnow was used to calculate population growth rates from these relationships. The population threshold concentrations (PTCs) leading to zero net growth of the fish population were as follows: Cu, 27.4; Cd, 33.2; Zn (soft water), 81.5; Zn (hard water), 85.8; Ni, 504.8; Cr, 3251.6 (microg L(-1)). By comparing the PTCs with no observed effect concentrations (NOECs), we found that some PTCs were equivalent to or even lower than the corresponding NOECs. This result suggests that current ecological risk assessments based on the NOECs can be inadequate for protecting aquatic populations and more efforts on the population-level studies are needed."
1233599,Gong et al. 2010,Stabilization of chromium: an alternative to make safe leathers,"In this study, the original causes for hexavalent chromium presence in the leather were first evaluated by ageing of chromium(III) solutions and chrome tanned hide powder (50 degrees C, UV lightening at 340 nm, 0-36 h). The results showed that the trivalent chromium at instable coordination state was easy to convert into hexavalent chromium in high pH environment, and the probability of the oxidation increased in this order: multi-coordinate chromium, mono-coordinate chromium, and free chromium. For this reason, the process for stabilizing chromium in the leather was designed with the specific material, which was mostly consisted of the reducers and the chelating agents. After treated with the developed process, these leathers were aged (50 degrees C, UV irradiance as 0.68 W/m(2) at 340 nm, 0-72 h) to estimate chromium(VI) presence. Hexavalent chromium was not found in these treated leathers even if the leathers were aged for 72 h. Moreover, the physical and mechanical properties for the leathers varied little after treating. In a word, an inherent safe and effective process was proved to avoid the formation of hexavalent chromium in the leather.","Stabilization of chromium: an alternative to make safe leathers Abs: In this study, the original causes for hexavalent chromium presence in the leather were first evaluated by ageing of chromium(III) solutions and chrome tanned hide powder (50 degrees C, UV lightening at 340 nm, 0-36 h). The results showed that the trivalent chromium at instable coordination state was easy to convert into hexavalent chromium in high pH environment, and the probability of the oxidation increased in this order: multi-coordinate chromium, mono-coordinate chromium, and free chromium. For this reason, the process for stabilizing chromium in the leather was designed with the specific material, which was mostly consisted of the reducers and the chelating agents. After treated with the developed process, these leathers were aged (50 degrees C, UV irradiance as 0.68 W/m(2) at 340 nm, 0-72 h) to estimate chromium(VI) presence. Hexavalent chromium was not found in these treated leathers even if the leathers were aged for 72 h. Moreover, the physical and mechanical properties for the leathers varied little after treating. In a word, an inherent safe and effective process was proved to avoid the formation of hexavalent chromium in the leather."
1233598,Liu et al. 2010,The Werner syndrome protein suppresses telomeric instability caused by chromium (VI) induced DNA replication stress,"Telomeres protect the chromosome ends and consist of guanine-rich repeats coated by specialized proteins. Critically short telomeres are associated with disease, aging and cancer. Defects in telomere replication can lead to telomere loss, which can be prevented by telomerase-mediated telomere elongation or activities of the Werner syndrome helicase/exonuclease protein (WRN). Both telomerase and WRN attenuate cytotoxicity induced by the environmental carcinogen hexavalent chromium (Cr(VI)), which promotes replication stress and DNA polymerase arrest. However, it is not known whether Cr(VI)-induced replication stress impacts telomere integrity. Here we report that Cr(VI) exposure of human fibroblasts induced telomeric damage as indicated by phosphorylated H2AX (gammaH2AX) at telomeric foci. The induced gammaH2AX foci occurred in S-phase cells, which is indicative of replication fork stalling or collapse. Telomere fluorescence in situ hybridization (FISH) of metaphase chromosomes revealed that Cr(VI) exposure induced an increase in telomere loss and sister chromatid fusions that were rescued by telomerase activity. Human cells depleted for WRN protein exhibited a delayed reduction in telomeric and non-telomeric damage, indicated by gammaH2AX foci, during recovery from Cr(VI) exposure, consistent with WRN roles in repairing damaged replication forks. Telomere FISH of chromosome spreads revealed that WRN protects against Cr(VI)-induced telomere loss and downstream chromosome fusions, but does not prevent chromosome fusions that retain telomere sequence at the fusion point. Our studies indicate that environmentally induced replication stress leads to telomere loss and aberrations that are suppressed by telomerase-mediated telomere elongation or WRN functions in replication fork restoration.","The Werner syndrome protein suppresses telomeric instability caused by chromium (VI) induced DNA replication stress Abs: Telomeres protect the chromosome ends and consist of guanine-rich repeats coated by specialized proteins. Critically short telomeres are associated with disease, aging and cancer. Defects in telomere replication can lead to telomere loss, which can be prevented by telomerase-mediated telomere elongation or activities of the Werner syndrome helicase/exonuclease protein (WRN). Both telomerase and WRN attenuate cytotoxicity induced by the environmental carcinogen hexavalent chromium (Cr(VI)), which promotes replication stress and DNA polymerase arrest. However, it is not known whether Cr(VI)-induced replication stress impacts telomere integrity. Here we report that Cr(VI) exposure of human fibroblasts induced telomeric damage as indicated by phosphorylated H2AX (gammaH2AX) at telomeric foci. The induced gammaH2AX foci occurred in S-phase cells, which is indicative of replication fork stalling or collapse. Telomere fluorescence in situ hybridization (FISH) of metaphase chromosomes revealed that Cr(VI) exposure induced an increase in telomere loss and sister chromatid fusions that were rescued by telomerase activity. Human cells depleted for WRN protein exhibited a delayed reduction in telomeric and non-telomeric damage, indicated by gammaH2AX foci, during recovery from Cr(VI) exposure, consistent with WRN roles in repairing damaged replication forks. Telomere FISH of chromosome spreads revealed that WRN protects against Cr(VI)-induced telomere loss and downstream chromosome fusions, but does not prevent chromosome fusions that retain telomere sequence at the fusion point. Our studies indicate that environmentally induced replication stress leads to telomere loss and aberrations that are suppressed by telomerase-mediated telomere elongation or WRN functions in replication fork restoration."
1233597,Geoffroy-Siraudin et al. 2010,Validation of a rat seminiferous tubule culture model as a suitable system for studying toxicant impact on meiosis effect of hexavalent chromium,"There is evidence that exposure to environmental factors is at least partly responsible for changes in semen quality observed over the past decades. The detection of reproductive toxicants under Registration, Evaluation and Authorisation of Chemicals (REACH) will impact animal use for regulatory safety testing. We first validated a model of culture of rat seminiferous tubules for toxicological studies on spermatogenesis. Then, using this model of culture, we assessed the deleterious effects of 1, 10, and 100 microg/l hexavalent chromium [Cr(VI)] on meiotic cells. The prophase I of meiosis was studied in vivo and ex vivo. Bromo-2'-deoxyuridine (BrdU) was used to describe the kinetics of germ cell differentiation. SCP3 labeling allowed to establish the distribution of the stages of the meiotic prophase I and to perform a qualitative study of the pachytene stage in the absence or presence of Cr(VI). The development of the meiotic step of pubertal rats was similar in vivo and ex vivo. The number of total cells appeared not affected by the presence of Cr(VI) irrespective of its concentration. However, the numbers of late spermatocytes and of round spermatids were decreased by Cr(VI) even at the lower concentration. The percentage of synaptonemal complex abnormalities increased slightly with the time of culture and dramatically with Cr(VI) concentrations. This model of culture appears suitable for toxicological studies. This study shows that Cr(VI) is toxic for meiotic cells even at low concentrations, and its toxicity increases in a dose-dependent manner.","Validation of a rat seminiferous tubule culture model as a suitable system for studying toxicant impact on meiosis effect of hexavalent chromium Abs: There is evidence that exposure to environmental factors is at least partly responsible for changes in semen quality observed over the past decades. The detection of reproductive toxicants under Registration, Evaluation and Authorisation of Chemicals (REACH) will impact animal use for regulatory safety testing. We first validated a model of culture of rat seminiferous tubules for toxicological studies on spermatogenesis. Then, using this model of culture, we assessed the deleterious effects of 1, 10, and 100 microg/l hexavalent chromium [Cr(VI)] on meiotic cells. The prophase I of meiosis was studied in vivo and ex vivo. Bromo-2'-deoxyuridine (BrdU) was used to describe the kinetics of germ cell differentiation. SCP3 labeling allowed to establish the distribution of the stages of the meiotic prophase I and to perform a qualitative study of the pachytene stage in the absence or presence of Cr(VI). The development of the meiotic step of pubertal rats was similar in vivo and ex vivo. The number of total cells appeared not affected by the presence of Cr(VI) irrespective of its concentration. However, the numbers of late spermatocytes and of round spermatids were decreased by Cr(VI) even at the lower concentration. The percentage of synaptonemal complex abnormalities increased slightly with the time of culture and dramatically with Cr(VI) concentrations. This model of culture appears suitable for toxicological studies. This study shows that Cr(VI) is toxic for meiotic cells even at low concentrations, and its toxicity increases in a dose-dependent manner."
1233596,Hazane-Puch et al. 2010,Chromium III histidinate exposure modulates gene expression in HaCaT human keratinocytes exposed to oxidative stress,"While the toxicity of hexavalent chromium is well established, trivalent chromium is an essential nutrient involved in insulin and glucose homeostasis. To study the antioxidant effects of Cr(III)His, cDNA arrays were used to investigate the modulation of gene expression by trivalent chromium histidinate (Cr(III)His) in HaCaT human keratinocytes submitted to hydrogen peroxide (H2O2). Array was composed by a set of 81 expressed sequences tags (ESTs) essentially represented by antioxidant and DNA repair genes. HaCaT were preincubated for 24 h with 50 microM Cr(III)His and were treated with 50 muM H2O2. Total RNAs were isolated immediately or 6 h after the stress. In Cr(III)His preincubated cells, transcripts related to antioxidant family were upregulated (glutathione synthetase, heme oxygenase 2, peroxiredoxin 4). In Cr(III)His preincubated cells and exposed to H2O2, increased expressions of polymerase delta 2 and antioxidant transcripts were observed. Biochemical methods performed in parallel to measure oxidative stress in cells showed that Cr(III)His supplementation before H2O2 stress protected HaCaT from thiol groups decrease and thiobarbituric acid reactive substances increase. In summary, these results give evidence of antioxidant gene expression and antioxidant protection in HaCaT preincubated with Cr(III)His and help to explain the lack of toxicity reported for Cr(III)His.","Chromium III histidinate exposure modulates gene expression in HaCaT human keratinocytes exposed to oxidative stress Abs: While the toxicity of hexavalent chromium is well established, trivalent chromium is an essential nutrient involved in insulin and glucose homeostasis. To study the antioxidant effects of Cr(III)His, cDNA arrays were used to investigate the modulation of gene expression by trivalent chromium histidinate (Cr(III)His) in HaCaT human keratinocytes submitted to hydrogen peroxide (H2O2). Array was composed by a set of 81 expressed sequences tags (ESTs) essentially represented by antioxidant and DNA repair genes. HaCaT were preincubated for 24 h with 50 microM Cr(III)His and were treated with 50 muM H2O2. Total RNAs were isolated immediately or 6 h after the stress. In Cr(III)His preincubated cells, transcripts related to antioxidant family were upregulated (glutathione synthetase, heme oxygenase 2, peroxiredoxin 4). In Cr(III)His preincubated cells and exposed to H2O2, increased expressions of polymerase delta 2 and antioxidant transcripts were observed. Biochemical methods performed in parallel to measure oxidative stress in cells showed that Cr(III)His supplementation before H2O2 stress protected HaCaT from thiol groups decrease and thiobarbituric acid reactive substances increase. In summary, these results give evidence of antioxidant gene expression and antioxidant protection in HaCaT preincubated with Cr(III)His and help to explain the lack of toxicity reported for Cr(III)His."
1233595,Dubber and  Gray 2010,Replacement of chemical oxygen demand (COD) with total organic carbon (TOC) for monitoring wastewater treatment performance to minimize disposal of toxic analytical waste,"Chemical oxygen demand (COD) is widely used for wastewater monitoring, design, modeling and plant operational analysis. However this method results in the production of hazardous wastes including mercury and hexavalent chromium. The study examined the replacement of COD with total organic carbon (TOC) for general performance monitoring by comparing their relationship with influent and effluent samples from 11 wastewater treatment plants. Biochemical oxygen demand (BOD5) was also included in the comparison as a control. The results show significant linear relationships between TOC, COD and BOD5 in settled (influent) domestic and municipal wastewaters, but only between COD and TOC in treated effluents. The study concludes that TOC can be reliably used for the generic replacement of both COD (COD=49.2+3.00*TOC) and BOD5 (BOD5=23.7+1.68*TOC) in influent wastewaters but only for COD (COD=7.25+2.99*TOC) in final effluents.","Replacement of chemical oxygen demand (COD) with total organic carbon (TOC) for monitoring wastewater treatment performance to minimize disposal of toxic analytical waste Abs: Chemical oxygen demand (COD) is widely used for wastewater monitoring, design, modeling and plant operational analysis. However this method results in the production of hazardous wastes including mercury and hexavalent chromium. The study examined the replacement of COD with total organic carbon (TOC) for general performance monitoring by comparing their relationship with influent and effluent samples from 11 wastewater treatment plants. Biochemical oxygen demand (BOD5) was also included in the comparison as a control. The results show significant linear relationships between TOC, COD and BOD5 in settled (influent) domestic and municipal wastewaters, but only between COD and TOC in treated effluents. The study concludes that TOC can be reliably used for the generic replacement of both COD (COD=49.2+3.00*TOC) and BOD5 (BOD5=23.7+1.68*TOC) in influent wastewaters but only for COD (COD=7.25+2.99*TOC) in final effluents."
1233594,Chiu et al. 2010,"Review of chromium (VI) apoptosis, cell-cycle-arrest, and carcinogenesis","Hexavalent chromium combines with glutathione in chloride intracellular channel carrier to form tetravalent and pentavalent chromium in plasma and organelle membranes. It also combines with NADH/NADPH to form pentavalent chromium in mitochondria. Tetravalent- and pentavalent- chromium (directly and indirectly) mediated DNA double strand breaks activate DNA damage signaling sensors: DNA-dependent-protein-kinase signals p53-dependent intrinsic mitochondrial apoptosis, and ataxia-telangiectasia-mutated and ataxia-telangiectasia-Rad3-related signal cell-arrest for DNA repair. Tetravalent chromium may be the most potent species since it causes DNA breaks and somatic recombination, but not apoptosis. Upon further failure of apoptosis and senescence/DNA-repair, damaged cells may become immortal with loss-of-heterozygosity and genetic plasticity.","Review of chromium (VI) apoptosis, cell-cycle-arrest, and carcinogenesis Abs: Hexavalent chromium combines with glutathione in chloride intracellular channel carrier to form tetravalent and pentavalent chromium in plasma and organelle membranes. It also combines with NADH/NADPH to form pentavalent chromium in mitochondria. Tetravalent- and pentavalent- chromium (directly and indirectly) mediated DNA double strand breaks activate DNA damage signaling sensors: DNA-dependent-protein-kinase signals p53-dependent intrinsic mitochondrial apoptosis, and ataxia-telangiectasia-mutated and ataxia-telangiectasia-Rad3-related signal cell-arrest for DNA repair. Tetravalent chromium may be the most potent species since it causes DNA breaks and somatic recombination, but not apoptosis. Upon further failure of apoptosis and senescence/DNA-repair, damaged cells may become immortal with loss-of-heterozygosity and genetic plasticity."
1233592,Itskos et al. 2010,Comparative uptake study of toxic elements from aqueous media by the different particle-size-fractions of fly ash,"The purpose of the study described in this paper was to determine the removal of Cr (total), Cr (VI), Cu, Ni, Pb, Zn and Cd from wastewater using different particle-size-fractions of highly calcareous and highly siliceous fly ashes (FAs). Three different Hellenic FAs (two calcareous and one siliceous) were tested for their capability of precipitating heavy metals from aqueous solutions. Each FA sample was separated into six different size-fractions with a grain diameter range of: [(0-25) (25-40) (40-90) (90-150) (150-400) and (&gt;400)] ?m. The different FA grain-fractions were evaluated in terms of their chemical composition, pH, Loss on Ignition (LOI) and CaO(f) (%). Batch adsorption experiments were then carried out, indicating that the various grain-fractions of the highly siliceous FA were more efficient in precipitating Cr (VI) but less capable of retaining Cd, Cu, Ni, Pb and Zn. On the other hand, the high-Ca fly ashes were proven to be more efficient in uptaking Cd, Cu, Ni, Pb and Zn, but less in hexavalent chromium. This particular tendency was also confirmed in the case of the different particle-size-fractions of same fly ashes. It was actually verified that FAs can be more effective in the field of industrial wastewater-remediation when separated into their size-fractions.","Comparative uptake study of toxic elements from aqueous media by the different particle-size-fractions of fly ash Abs: The purpose of the study described in this paper was to determine the removal of Cr (total), Cr (VI), Cu, Ni, Pb, Zn and Cd from wastewater using different particle-size-fractions of highly calcareous and highly siliceous fly ashes (FAs). Three different Hellenic FAs (two calcareous and one siliceous) were tested for their capability of precipitating heavy metals from aqueous solutions. Each FA sample was separated into six different size-fractions with a grain diameter range of: [(0-25) (25-40) (40-90) (90-150) (150-400) and (&gt;400)] ?m. The different FA grain-fractions were evaluated in terms of their chemical composition, pH, Loss on Ignition (LOI) and CaO(f) (%). Batch adsorption experiments were then carried out, indicating that the various grain-fractions of the highly siliceous FA were more efficient in precipitating Cr (VI) but less capable of retaining Cd, Cu, Ni, Pb and Zn. On the other hand, the high-Ca fly ashes were proven to be more efficient in uptaking Cd, Cu, Ni, Pb and Zn, but less in hexavalent chromium. This particular tendency was also confirmed in the case of the different particle-size-fractions of same fly ashes. It was actually verified that FAs can be more effective in the field of industrial wastewater-remediation when separated into their size-fractions."
1233591,Mahmood et al. 2010,Histopathological and biochemical changes in rat thyroid following acute exposure to hexavalent chromium,"Chromium in hexavalent form is highly toxic and a known carcinogen, although its effects on thyroid structure and function are relatively unexplored. Workers in an industrial environment can be, at times, exposed to this form of chromium. The present study was, therefore, designed using laboratory rats as a model system to investigate the effect on thyroid structure and function following two acute intraperitoneal doses of 30 mg/kg b.w. potassium dichromate administered within 48 hours. The results showed that hypothalamic chromium concentration increased (p&lt;0.05) while thyroid chromium concentration decreased (p&lt;0.01).The excretion of chromium in urine increased (p&lt;0.05). The treated thyroid sections revealed hyperplasia. Follicles were disorganized, clustered and collapsed, while some of them were fused. Interfollicular spaces widened. Morphometrical analysis showed significantly (p&lt;0.001) increased number of follicles whereas the follicular size significantly decreased (p&lt;0.001). Nuclei were regressed (p&lt;0.001); nuclear shapes were irregular; round, oval and shrunken. The membrane on the apical as well as the basal lamina side showed disruption. Colloid retraction within the follicles was noticeable in some sections stained with Periodic acid Schiff (PAS). Serum free tetra-iodothyronine (FT4) and free tri-iodothyronine (FT3) levels decreased (p&lt;0.01 and p&lt;0.001, respectively), while serum thyroid stimulating hormone (TSH) concentration increased (p&lt;0.01). Ultrastructural analysis showed disrupted basal laminae of the follicles, regressed nuclei and disrupted cell organelles. Acridine orange stained thyroid cells demonstrated excessive dead cells, whereas DNA fragmentation assay demonstrated percent decrease of hypothalamic, pituitary and thyroidal total DNA.","Histopathological and biochemical changes in rat thyroid following acute exposure to hexavalent chromium Abs: Chromium in hexavalent form is highly toxic and a known carcinogen, although its effects on thyroid structure and function are relatively unexplored. Workers in an industrial environment can be, at times, exposed to this form of chromium. The present study was, therefore, designed using laboratory rats as a model system to investigate the effect on thyroid structure and function following two acute intraperitoneal doses of 30 mg/kg b.w. potassium dichromate administered within 48 hours. The results showed that hypothalamic chromium concentration increased (p&lt;0.05) while thyroid chromium concentration decreased (p&lt;0.01).The excretion of chromium in urine increased (p&lt;0.05). The treated thyroid sections revealed hyperplasia. Follicles were disorganized, clustered and collapsed, while some of them were fused. Interfollicular spaces widened. Morphometrical analysis showed significantly (p&lt;0.001) increased number of follicles whereas the follicular size significantly decreased (p&lt;0.001). Nuclei were regressed (p&lt;0.001); nuclear shapes were irregular; round, oval and shrunken. The membrane on the apical as well as the basal lamina side showed disruption. Colloid retraction within the follicles was noticeable in some sections stained with Periodic acid Schiff (PAS). Serum free tetra-iodothyronine (FT4) and free tri-iodothyronine (FT3) levels decreased (p&lt;0.01 and p&lt;0.001, respectively), while serum thyroid stimulating hormone (TSH) concentration increased (p&lt;0.01). Ultrastructural analysis showed disrupted basal laminae of the follicles, regressed nuclei and disrupted cell organelles. Acridine orange stained thyroid cells demonstrated excessive dead cells, whereas DNA fragmentation assay demonstrated percent decrease of hypothalamic, pituitary and thyroidal total DNA."
1233590,Liu et al. 2010,Entrapment of nanoscale zero-valent iron in chitosan beads for hexavalent chromium removal from wastewater,Nanoscale zero-valent iron (NZVI) was successfully entrapped in chitosan (CS) beads for reduction of Cr (VI) from wastewater. The removal mechanism may include both physical adsorption of Cr (VI) on the surface or inside of CS-NZVI beads and subsequent reduction of Cr (VI) to Cr (III). The free amino groups and hydroxyl groups on CS may contribute little to hinder the formation of Fe(III)-Cr(III) precipitate. Entrapment of NZVI in CS beads prevents the particles from aggregation and oxidation. The results indicate that there is no significant difference between the reaction rates of bare NZVI and entrapped NZVI. Cr (VI) reduction kinetics follows a pseudo-first-order rate expression. The reduction capacity for Cr (VI) increases with increasing temperature and NZVI dosage but decreases with the increase in initial concentration of Cr (VI) and pH values. This study demonstrates that entrapment of NZVI in CS beads has the potential to become a promising technique for in situ groundwater remediation.,Entrapment of nanoscale zero-valent iron in chitosan beads for hexavalent chromium removal from wastewater Abs: Nanoscale zero-valent iron (NZVI) was successfully entrapped in chitosan (CS) beads for reduction of Cr (VI) from wastewater. The removal mechanism may include both physical adsorption of Cr (VI) on the surface or inside of CS-NZVI beads and subsequent reduction of Cr (VI) to Cr (III). The free amino groups and hydroxyl groups on CS may contribute little to hinder the formation of Fe(III)-Cr(III) precipitate. Entrapment of NZVI in CS beads prevents the particles from aggregation and oxidation. The results indicate that there is no significant difference between the reaction rates of bare NZVI and entrapped NZVI. Cr (VI) reduction kinetics follows a pseudo-first-order rate expression. The reduction capacity for Cr (VI) increases with increasing temperature and NZVI dosage but decreases with the increase in initial concentration of Cr (VI) and pH values. This study demonstrates that entrapment of NZVI in CS beads has the potential to become a promising technique for in situ groundwater remediation.
1233589,Samani et al. 2010,Removal of chromium from aqueous solution using polyaniline--poly ethylene glycol composite,"The adsorption of chromium compounds from solutions by a composite of polyaniline/poly ethylene glycol (PANi/PEG) was investigated in this study. Experiments were conducted in batch mode under various operational conditions including agitation time, solution pH, PANi/PEG dose and initial concentration of chromium salts. Results showed that concentration of PEG at synthesizing stage has a significant effect on the capacity of produced composite for removal of chromium. Morphologically, PANi/PEG composite is closely dependent on the concentration of PEG. Maximum removal of hexavalent chromium was experienced when 2g/L of PEG was used in synthesis of PANi/PEG. Removal of hexavalent chromium by PANi/PEG composite included surface adsorption and reduction reaction. The optimum pH was 5 and the equilibrium time for hexavalent chromium removal was about 30 min. Investigation of the isothermal characteristics showed that chromium adsorption by PANi/PEG composite was in high accordance with Langmuir's isotherm.","Removal of chromium from aqueous solution using polyaniline--poly ethylene glycol composite Abs: The adsorption of chromium compounds from solutions by a composite of polyaniline/poly ethylene glycol (PANi/PEG) was investigated in this study. Experiments were conducted in batch mode under various operational conditions including agitation time, solution pH, PANi/PEG dose and initial concentration of chromium salts. Results showed that concentration of PEG at synthesizing stage has a significant effect on the capacity of produced composite for removal of chromium. Morphologically, PANi/PEG composite is closely dependent on the concentration of PEG. Maximum removal of hexavalent chromium was experienced when 2g/L of PEG was used in synthesis of PANi/PEG. Removal of hexavalent chromium by PANi/PEG composite included surface adsorption and reduction reaction. The optimum pH was 5 and the equilibrium time for hexavalent chromium removal was about 30 min. Investigation of the isothermal characteristics showed that chromium adsorption by PANi/PEG composite was in high accordance with Langmuir's isotherm."
1233588,Das and  Mishra 2010,Biodegradation of the metallic carcinogen hexavalent chromium Cr(VI) by an indigenously isolated bacterial strain,"<strong>BACKGROUND: </strong>Hexavalent chromium [Cr(VI)], a potential mutagen and carcinogen, is regularly introduced into the environment through diverse anthropogenic activities, including electroplating, leather tanning, and pigment manufacturing. Human exposure to this toxic metal ion not only causes potential human health hazards but also affects other life forms. The World Health Organization, the International Agency for Research on Cancer, and the Environmental Protection Agency have determined that Cr(VI) compounds are known human carcinogens. The Sukinda valley in Jajpur District, Orissa, is known for its deposit of chromite ore, producing nearly 98% of the chromite ore in India and one of the prime open cast chromite ore mines in the world (CES, Orissa Newsletter).<br /><br /><strong>MATERIALS AND METHODS: </strong>Our investigation involved microbial remediation of Cr(VI) without producing any byproduct. Bacterial cultures tolerating high concentrations of Cr were isolated from the soil sample collected from the chromite-contaminated sites of Sukinda, and their bioaccumulation properties were investigated. Strains capable of growing at 250 mg/L Cr(VI) were considered as Cr resistant.<br /><br /><strong>RESULTS: </strong>The experimental investigation showed the maximum specific Cr uptake at pH 7 and temperature 30°C. At about 50 mg/L initial Cr(VI) concentrations, uptake of the selected potential strain exceeded 98% within 12 h of incubation. The bacterial isolate was identified by 16S rRNA sequencing as Brevebacterium casei.<br /><br /><strong>CONCLUSION: </strong>Results indicated promising approach for microbial remediation of effluents containing elevated levels of Cr(VI).","Biodegradation of the metallic carcinogen hexavalent chromium Cr(VI) by an indigenously isolated bacterial strain Abs: <strong>BACKGROUND: </strong>Hexavalent chromium [Cr(VI)], a potential mutagen and carcinogen, is regularly introduced into the environment through diverse anthropogenic activities, including electroplating, leather tanning, and pigment manufacturing. Human exposure to this toxic metal ion not only causes potential human health hazards but also affects other life forms. The World Health Organization, the International Agency for Research on Cancer, and the Environmental Protection Agency have determined that Cr(VI) compounds are known human carcinogens. The Sukinda valley in Jajpur District, Orissa, is known for its deposit of chromite ore, producing nearly 98% of the chromite ore in India and one of the prime open cast chromite ore mines in the world (CES, Orissa Newsletter).<br /><br /><strong>MATERIALS AND METHODS: </strong>Our investigation involved microbial remediation of Cr(VI) without producing any byproduct. Bacterial cultures tolerating high concentrations of Cr were isolated from the soil sample collected from the chromite-contaminated sites of Sukinda, and their bioaccumulation properties were investigated. Strains capable of growing at 250 mg/L Cr(VI) were considered as Cr resistant.<br /><br /><strong>RESULTS: </strong>The experimental investigation showed the maximum specific Cr uptake at pH 7 and temperature 30°C. At about 50 mg/L initial Cr(VI) concentrations, uptake of the selected potential strain exceeded 98% within 12 h of incubation. The bacterial isolate was identified by 16S rRNA sequencing as Brevebacterium casei.<br /><br /><strong>CONCLUSION: </strong>Results indicated promising approach for microbial remediation of effluents containing elevated levels of Cr(VI)."
1233587,Liu et al. 2010,Optical study of the reduction of hexavalent chromium by iron-based nanoparticles,"In this paper, a simple method was presented to measure the concentration change in the Cr(VI)-contained waste water during treatment by nanoparticles, based on its optical absorption spectral evolution which exhibits a good linear relationship between the absorbance of the peak at 348 nm and Cr6+ ion concentration. The iron and Fe/Pd bimetal nanoparticles were prepared and used for removal of Cr6+ in waste water. It has been found that presented method for concentration determination based on optical spectral evolution is effective and flexible. The nanoparticles have higher efficiency than normal iron powders and Fe/Pd bimetallic nanoparticles show faster removal of the Cr6+ than iron nanoparticles. The study is of importance in environmental remediation or pollution treatment of heavy metal ions in water and even soil.","Optical study of the reduction of hexavalent chromium by iron-based nanoparticles Abs: In this paper, a simple method was presented to measure the concentration change in the Cr(VI)-contained waste water during treatment by nanoparticles, based on its optical absorption spectral evolution which exhibits a good linear relationship between the absorbance of the peak at 348 nm and Cr6+ ion concentration. The iron and Fe/Pd bimetal nanoparticles were prepared and used for removal of Cr6+ in waste water. It has been found that presented method for concentration determination based on optical spectral evolution is effective and flexible. The nanoparticles have higher efficiency than normal iron powders and Fe/Pd bimetallic nanoparticles show faster removal of the Cr6+ than iron nanoparticles. The study is of importance in environmental remediation or pollution treatment of heavy metal ions in water and even soil."
1233586,Halasova et al. 2010,Lung cancer incidence and survival in chromium exposed individuals with respect to expression of anti-apoptotic protein survivin and tumor suppressor P53 protein,"<strong>OBJECTIVE: </strong>Workers chronically exposed to hexavalent chromium have elevated risk of lung cancer. Our study investigates the incidence of lung cancer types, age at onset of the disease, and survival time among chromium exposed workers with respect to the expression of anti-apoptotic p53 and pro-apoptotic survivin proteins.<br /><br /><strong>MATERIAL AND METHODS: </strong>67 chromium exposed workers and 104 male controls diagnosed with lung cancer were analyzed. The mean exposure time among workers was 16.7 ±10.0(SD) years (range 1- 41 years). To investigate the possible regulation of survivin by p53 we examined the expression of both proteins using immohistochemical visualization.<br /><br /><strong>RESULTS: </strong>Chromium exposure significantly decreases the age of onset of the disease by 3.5 years (62.2 ±9.1 in the exposed group vs. 65.7 ±10.5 years in controls; P=0.018). Small cell lung carcinoma (SCLC) amounted for 25.4% of all cases in chromium exposed workers and for 16.3% in non-exposed individuals. The mean survival time in the exposed group was 9.0 ±12.7 vs. 12.1 ±21.9 months in controls, but this difference was not significant. Survivin was predominantly expressed in both cell nucleus and cytoplasm, whereas p53 was expressed in the nucleus. There was a negative correlation between survivin and p53 expression. A decreased intensity of expression and fewer cells positive for survivin was detected in SCLC compared with other types of lung cancer. p53 was expressed in 94.1% and survivin in 79.6% of the samples analyzed.<br /><br /><strong>CONCLUSION: </strong>The study calls attention to decreased expression of survivin, as opposed to p53, in small cell lung carcinoma.","Lung cancer incidence and survival in chromium exposed individuals with respect to expression of anti-apoptotic protein survivin and tumor suppressor P53 protein Abs: <strong>OBJECTIVE: </strong>Workers chronically exposed to hexavalent chromium have elevated risk of lung cancer. Our study investigates the incidence of lung cancer types, age at onset of the disease, and survival time among chromium exposed workers with respect to the expression of anti-apoptotic p53 and pro-apoptotic survivin proteins.<br /><br /><strong>MATERIAL AND METHODS: </strong>67 chromium exposed workers and 104 male controls diagnosed with lung cancer were analyzed. The mean exposure time among workers was 16.7 ±10.0(SD) years (range 1- 41 years). To investigate the possible regulation of survivin by p53 we examined the expression of both proteins using immohistochemical visualization.<br /><br /><strong>RESULTS: </strong>Chromium exposure significantly decreases the age of onset of the disease by 3.5 years (62.2 ±9.1 in the exposed group vs. 65.7 ±10.5 years in controls; P=0.018). Small cell lung carcinoma (SCLC) amounted for 25.4% of all cases in chromium exposed workers and for 16.3% in non-exposed individuals. The mean survival time in the exposed group was 9.0 ±12.7 vs. 12.1 ±21.9 months in controls, but this difference was not significant. Survivin was predominantly expressed in both cell nucleus and cytoplasm, whereas p53 was expressed in the nucleus. There was a negative correlation between survivin and p53 expression. A decreased intensity of expression and fewer cells positive for survivin was detected in SCLC compared with other types of lung cancer. p53 was expressed in 94.1% and survivin in 79.6% of the samples analyzed.<br /><br /><strong>CONCLUSION: </strong>The study calls attention to decreased expression of survivin, as opposed to p53, in small cell lung carcinoma."
1233585,Rehr et al. 2010,Economic sources and spatial distribution of airborne chromium risks in the U.S,"We present a model that integrates the economic input-output approach of life cycle assessment with environmental fate, exposure, and risk assessment to estimate the spatial distribution of air toxic health risks due to sector-specific economic activity in the U.S. The model is used to relate the economic activity and exposure potential (population density and meteorology) associated with point source emissions of the heavy metal and carcinogen, hexavalent chromium, or Cr(VI), on a county basis. Total direct annual airborne emissions of Cr(VI) in the U.S. were 44 tonnes in 2002, with 97% from facilities in four major sectors: power generation, wood, plastics, and chemicals, metals, and scientific services. These include 6 tonnes of Cr(VI) emitted in the supply chains of these sectors. A highly variable national distribution of lifetime cancer risk is predicted, with a population-weighted mean of 2.7 x 10(-7), but with hot-spot counties with lifetime risks as high as 6 x 10(-6). Furthermore, high exposures and risks tend to occur in more highly populated counties. In particular, the population of Los Angeles County is exposed to the highest level of risk in the country and almost three-quarters of the total predicted cancer incidence due to inhalation of airborne Cr(VI) emissions. This finding can be attributed largely to the use of Cr(VI) as a corrosion inhibitor by the scientific services sector facilities in the county, the use of shorter facility stacks, and their sitting within a highly populated area. These results indicate that linking economic activity, emission estimates, and fate and transport models for air toxics can inform both life cycle impact and comparative health risk assessments, allowing us to better target emission reductions to minimize hot-spots of risk.","Economic sources and spatial distribution of airborne chromium risks in the U.S Abs: We present a model that integrates the economic input-output approach of life cycle assessment with environmental fate, exposure, and risk assessment to estimate the spatial distribution of air toxic health risks due to sector-specific economic activity in the U.S. The model is used to relate the economic activity and exposure potential (population density and meteorology) associated with point source emissions of the heavy metal and carcinogen, hexavalent chromium, or Cr(VI), on a county basis. Total direct annual airborne emissions of Cr(VI) in the U.S. were 44 tonnes in 2002, with 97% from facilities in four major sectors: power generation, wood, plastics, and chemicals, metals, and scientific services. These include 6 tonnes of Cr(VI) emitted in the supply chains of these sectors. A highly variable national distribution of lifetime cancer risk is predicted, with a population-weighted mean of 2.7 x 10(-7), but with hot-spot counties with lifetime risks as high as 6 x 10(-6). Furthermore, high exposures and risks tend to occur in more highly populated counties. In particular, the population of Los Angeles County is exposed to the highest level of risk in the country and almost three-quarters of the total predicted cancer incidence due to inhalation of airborne Cr(VI) emissions. This finding can be attributed largely to the use of Cr(VI) as a corrosion inhibitor by the scientific services sector facilities in the county, the use of shorter facility stacks, and their sitting within a highly populated area. These results indicate that linking economic activity, emission estimates, and fate and transport models for air toxics can inform both life cycle impact and comparative health risk assessments, allowing us to better target emission reductions to minimize hot-spots of risk."
1233584,Honeycutt 2011,Hexavalent chromium in Texas drinking water,,Hexavalent chromium in Texas drinking water Abs: 
1233583,Wienold et al. 2011,Elemental analysis of printed circuit boards considering the ROHS regulations,"The EU RoHS Directive (2002/95/EC of the European Parliament and of the Council) bans the placing of new electrical and electronic equipment containing more than agreed levels of lead, cadmium, mercury, hexavalent chromium, polybrominated biphenyl (PBB) and polybrominated diphenyl ether (PBDE) flame retardants on the EU market. It necessitates methods for the evaluation of RoHS compliance of assembled electronic equipment. In this study mounted printed circuit boards from personal computers were analyzed on their content of the three elements Cd, Pb and Hg which were limited by the EU RoHS directive. Main focus of the investigations was the influence of sample pre-treatment on the precision and reproducibility of the results. The sample preparation steps used were based on the guidelines given in EN 62321. Five different types of dissolution procedures were tested on different subsequent steps of sample treatment like cutting and milling. Elemental analysis was carried out using ICP-OES, XRF and CV-AFS (Hg). The results obtained showed that for decision-making with respect to RoHS compliance a size reduction of the material to be analyzed to particles ? 1.5mm can already be sufficient. However, to ensure analytical results with relative standard deviations of less than 20%, as recommended by the EN 62321, a much larger effort for sample processing towards smaller particle sizes might be required which strongly depends on the mass fraction of the element under investigation.","Elemental analysis of printed circuit boards considering the ROHS regulations Abs: The EU RoHS Directive (2002/95/EC of the European Parliament and of the Council) bans the placing of new electrical and electronic equipment containing more than agreed levels of lead, cadmium, mercury, hexavalent chromium, polybrominated biphenyl (PBB) and polybrominated diphenyl ether (PBDE) flame retardants on the EU market. It necessitates methods for the evaluation of RoHS compliance of assembled electronic equipment. In this study mounted printed circuit boards from personal computers were analyzed on their content of the three elements Cd, Pb and Hg which were limited by the EU RoHS directive. Main focus of the investigations was the influence of sample pre-treatment on the precision and reproducibility of the results. The sample preparation steps used were based on the guidelines given in EN 62321. Five different types of dissolution procedures were tested on different subsequent steps of sample treatment like cutting and milling. Elemental analysis was carried out using ICP-OES, XRF and CV-AFS (Hg). The results obtained showed that for decision-making with respect to RoHS compliance a size reduction of the material to be analyzed to particles ? 1.5mm can already be sufficient. However, to ensure analytical results with relative standard deviations of less than 20%, as recommended by the EN 62321, a much larger effort for sample processing towards smaller particle sizes might be required which strongly depends on the mass fraction of the element under investigation."
1233582,Soudani et al. 2011,Cardioprotective effects of selenium on chromium (VI)-induced toxicity in female rats,"Acute exposure to hexavalent chromium compounds can cause cardiotoxicity. Our study pertains to the protective effect of selenium against K(2)Cr(2)O(7)-induced cardiotoxicity. Female Wistar rats were divided into four groups of six each: group I served as controls which received standard diet; group II received in drinking water K(2)Cr(2)O(7) alone (700 ppm); group III received both K(2)Cr(2)O(7) and Se (0.5 Na(2)SeO(3) mg/kg of diet); group IV received Se (0.5 mg/kg of diet) for 3 weeks. The exposure of rats to chromium promoted oxidative stress with an increase in malondialdehyde levels and a decrease in antioxidant non-enzymatic levels such as glutathione, non-protein thiol and vitamin C, while, an increase in glutathione peroxidase, superoxide dismutase and catalase activities was observed. However, plasma transaminases, lactate dehydrogenase activities, cholesterol, triglycerides and low density lipoprotein-cholesterol levels increased, and high density lipoprotein-cholesterol decreased. Coadministration of Se restored the parameters cited above to near-normal values. The histopathological findings confirmed the biochemical results.","Cardioprotective effects of selenium on chromium (VI)-induced toxicity in female rats Abs: Acute exposure to hexavalent chromium compounds can cause cardiotoxicity. Our study pertains to the protective effect of selenium against K(2)Cr(2)O(7)-induced cardiotoxicity. Female Wistar rats were divided into four groups of six each: group I served as controls which received standard diet; group II received in drinking water K(2)Cr(2)O(7) alone (700 ppm); group III received both K(2)Cr(2)O(7) and Se (0.5 Na(2)SeO(3) mg/kg of diet); group IV received Se (0.5 mg/kg of diet) for 3 weeks. The exposure of rats to chromium promoted oxidative stress with an increase in malondialdehyde levels and a decrease in antioxidant non-enzymatic levels such as glutathione, non-protein thiol and vitamin C, while, an increase in glutathione peroxidase, superoxide dismutase and catalase activities was observed. However, plasma transaminases, lactate dehydrogenase activities, cholesterol, triglycerides and low density lipoprotein-cholesterol levels increased, and high density lipoprotein-cholesterol decreased. Coadministration of Se restored the parameters cited above to near-normal values. The histopathological findings confirmed the biochemical results."
1233580,Sun et al. 2011,Comparison of gene expression profiles in chromate transformed BEAS-2B cells,"<strong>BACKGROUND: </strong>Hexavalent chromium [Cr(VI)] is a potent human carcinogen. Occupational exposure has been associated with increased risk of respiratory cancer. Multiple mechanisms have been shown to contribute to Cr(VI) induced carcinogenesis, including DNA damage, genomic instability, and epigenetic modulation, however, the molecular mechanism and downstream genes mediating chromium's carcinogenicity remain to be elucidated.<br /><br /><strong>METHODS/RESULTS: </strong>We established chromate transformed cell lines by chronic exposure of normal human bronchial epithelial BEAS-2B cells to low doses of Cr(VI) followed by anchorage-independent growth. These transformed cell lines not only exhibited consistent morphological changes but also acquired altered and distinct gene expression patterns compared with normal BEAS-2B cells and control cell lines (untreated) that arose spontaneously in soft agar. Interestingly, the gene expression profiles of six Cr(VI) transformed cell lines were remarkably similar to each other yet differed significantly from that of either control cell lines or normal BEAS-2B cells. A total of 409 differentially expressed genes were identified in Cr(VI) transformed cells compared to control cells. Genes related to cell-to-cell junction were upregulated in all Cr(VI) transformed cells, while genes associated with the interaction between cells and their extracellular matrices were down-regulated. Additionally, expression of genes involved in cell proliferation and apoptosis were also changed.<br /><br /><strong>CONCLUSION: </strong>This study is the first to report gene expression profiling of Cr(VI) transformed cells. The gene expression changes across individual chromate exposed clones were remarkably similar to each other but differed significantly from the gene expression found in anchorage-independent clones that arose spontaneously. Our analysis identified many novel gene expression changes that may contribute to chromate induced cell transformation, and collectively this type of information will provide a better understanding of the mechanism underlying chromate carcinogenicity.","Comparison of gene expression profiles in chromate transformed BEAS-2B cells Abs: <strong>BACKGROUND: </strong>Hexavalent chromium [Cr(VI)] is a potent human carcinogen. Occupational exposure has been associated with increased risk of respiratory cancer. Multiple mechanisms have been shown to contribute to Cr(VI) induced carcinogenesis, including DNA damage, genomic instability, and epigenetic modulation, however, the molecular mechanism and downstream genes mediating chromium's carcinogenicity remain to be elucidated.<br /><br /><strong>METHODS/RESULTS: </strong>We established chromate transformed cell lines by chronic exposure of normal human bronchial epithelial BEAS-2B cells to low doses of Cr(VI) followed by anchorage-independent growth. These transformed cell lines not only exhibited consistent morphological changes but also acquired altered and distinct gene expression patterns compared with normal BEAS-2B cells and control cell lines (untreated) that arose spontaneously in soft agar. Interestingly, the gene expression profiles of six Cr(VI) transformed cell lines were remarkably similar to each other yet differed significantly from that of either control cell lines or normal BEAS-2B cells. A total of 409 differentially expressed genes were identified in Cr(VI) transformed cells compared to control cells. Genes related to cell-to-cell junction were upregulated in all Cr(VI) transformed cells, while genes associated with the interaction between cells and their extracellular matrices were down-regulated. Additionally, expression of genes involved in cell proliferation and apoptosis were also changed.<br /><br /><strong>CONCLUSION: </strong>This study is the first to report gene expression profiling of Cr(VI) transformed cells. The gene expression changes across individual chromate exposed clones were remarkably similar to each other but differed significantly from the gene expression found in anchorage-independent clones that arose spontaneously. Our analysis identified many novel gene expression changes that may contribute to chromate induced cell transformation, and collectively this type of information will provide a better understanding of the mechanism underlying chromate carcinogenicity."
1233579,Zhang and  Li 2011,Isolation and characterization of a chromium-resistant bacterium Serratia sp. Cr-10 from a chromate-contaminated site,"A novel bacterium, Cr-10, was isolated from a chromium-contaminated site and capable of removing toxic chromium species from solution by reducing hexavalent chromium to an insoluble precipitate. Sequence analysis of 16S rRNA gene of strain Cr-10 showed that it was most closely related to Serratia rubidaea JCM 1240(T) (97.68%). Physiological and chemotaxonomic data also supported that strain Cr-10 was identified as Serratia sp., a genus which was never specially reported chromate-resistant before. Serratia sp., Cr-10 was tolerant to a concentration of 1,500 mg Cr(VI) L(-1), which was the highest level reported until now. The optimum pH and temperature for reduction of Cr(VI) by Serratia sp. Cr-10 were found to be 7.0 and 37 °C, respectively. The Cr(VI) reduction was significantly influenced by additional carbon sources, and among them fructose and lactose offered maximum reduction, with a rate of 0.28 and 0.25 mg Cr(VI) L(-1) h(-1), respectively. The cell-free extracts and filtrate of the culture were able to reduce Cr(VI) while concentration of total chromium remained stable in the process, indicating that the enzyme-catalyzed mechanism was applied in Cr(VI) reduction by the isolate. Additionally, it was found that there was hardly any chromium on the cell surface of the strain, further supporting that reduction, rather than bioadsorption, plays a major role in the Cr(VI) removal.","Isolation and characterization of a chromium-resistant bacterium Serratia sp. Cr-10 from a chromate-contaminated site Abs: A novel bacterium, Cr-10, was isolated from a chromium-contaminated site and capable of removing toxic chromium species from solution by reducing hexavalent chromium to an insoluble precipitate. Sequence analysis of 16S rRNA gene of strain Cr-10 showed that it was most closely related to Serratia rubidaea JCM 1240(T) (97.68%). Physiological and chemotaxonomic data also supported that strain Cr-10 was identified as Serratia sp., a genus which was never specially reported chromate-resistant before. Serratia sp., Cr-10 was tolerant to a concentration of 1,500 mg Cr(VI) L(-1), which was the highest level reported until now. The optimum pH and temperature for reduction of Cr(VI) by Serratia sp. Cr-10 were found to be 7.0 and 37 °C, respectively. The Cr(VI) reduction was significantly influenced by additional carbon sources, and among them fructose and lactose offered maximum reduction, with a rate of 0.28 and 0.25 mg Cr(VI) L(-1) h(-1), respectively. The cell-free extracts and filtrate of the culture were able to reduce Cr(VI) while concentration of total chromium remained stable in the process, indicating that the enzyme-catalyzed mechanism was applied in Cr(VI) reduction by the isolate. Additionally, it was found that there was hardly any chromium on the cell surface of the strain, further supporting that reduction, rather than bioadsorption, plays a major role in the Cr(VI) removal."
1233578,Marouani et al. 2011,Embryotoxicity and fetotoxicity following intraperitoneal administrations of hexavalent chromium to pregnant rats,"Heavy metals are omnipresent in the environment, and industrial use has greatly increased their presence in soil, water and air. Their inevitable transfer to the human food chain remains an important environmental issue as many heavy metals cause a range of toxic effects, including developmental toxicity. Administration of chromium VI (1 and 2 mg/kg as potassium dichromate) through intraperitoneal (i.p.) injection during organogenesis (days 6 to 15 of gestation) in rats revealed embryo- and fetotoxic effects. Reduced fetal weight, retarded fetal development, number of fetuses per mother and high incidences of dead fetuses and resorptions in treated mothers were also observed. Gross morphological abnormalities, such as displayed form of edema, facial defect, lack of tail, hypotrophy, severs subdermal haemorrhage patches and hypotrophy of placenta were observed in fetuses after chromium VI-treated mothers. A skeletal development of fetuses presented an incomplete ossification in nasal, cranium, abdominal or caudal bones in rats treated with 1 mg/kg of chromium, whereas rats treated with 2 mg/kg showed ossification and absence of the sacral vertebrae compared with the control. At a higher dose of chromium, histological changes were found in fetuses with atrophy of theirs vital organs. Placental histological observations revealed a pronounced morphological alteration, with atrophy of decidual cells, a degenerated of chorionic villi and hypertrophy of blood lacuna. The present study suggests a risk to the developing embryo when the mother is exposed to a high concentration of chromium VI during organogenesis.","Embryotoxicity and fetotoxicity following intraperitoneal administrations of hexavalent chromium to pregnant rats Abs: Heavy metals are omnipresent in the environment, and industrial use has greatly increased their presence in soil, water and air. Their inevitable transfer to the human food chain remains an important environmental issue as many heavy metals cause a range of toxic effects, including developmental toxicity. Administration of chromium VI (1 and 2 mg/kg as potassium dichromate) through intraperitoneal (i.p.) injection during organogenesis (days 6 to 15 of gestation) in rats revealed embryo- and fetotoxic effects. Reduced fetal weight, retarded fetal development, number of fetuses per mother and high incidences of dead fetuses and resorptions in treated mothers were also observed. Gross morphological abnormalities, such as displayed form of edema, facial defect, lack of tail, hypotrophy, severs subdermal haemorrhage patches and hypotrophy of placenta were observed in fetuses after chromium VI-treated mothers. A skeletal development of fetuses presented an incomplete ossification in nasal, cranium, abdominal or caudal bones in rats treated with 1 mg/kg of chromium, whereas rats treated with 2 mg/kg showed ossification and absence of the sacral vertebrae compared with the control. At a higher dose of chromium, histological changes were found in fetuses with atrophy of theirs vital organs. Placental histological observations revealed a pronounced morphological alteration, with atrophy of decidual cells, a degenerated of chorionic villi and hypertrophy of blood lacuna. The present study suggests a risk to the developing embryo when the mother is exposed to a high concentration of chromium VI during organogenesis."
1233577,Das and  Singh 2011,Occupational health assessment of chromite toxicity among Indian miners,"Elevated concentration of hexavalent chromium pollution and contamination has contributed a major health hazard affecting more than 2 lakh mine workers and inhabitants residing in the Sukinda chromite mine of Odisha, India. Despite people suffering from several forms of ill health, physical and mental deformities, constant exposure to toxic wastes and chronic diseases as a result of chromite mining, there is a tragic gap in the availability of 'scientific' studies and data on the health hazards of mining in India. Occupational Safety and Health Administration, Odisha State Pollution Control Board and the Odisha Voluntary Health Association data were used to compile the possible occupational health hazards, hexavalent chromium exposure and diseases among Sukinda chromite mines workers. Studies were reviewed to determine the routes of exposure and possible mechanism of chromium induced carcinogenicity among the workers. Our studies suggest all forms of hexavalent chromium are regarded as carcinogenic to workers however the most important routes of occupational exposure to Cr (VI) are inhalation and dermal contact. This review article outlines the physical, chemical, biological and psychosocial occupational health hazards of chromite mining and associated metallurgical processes to monitor the mining environment as well as the miners exposed to these toxicants to foster a safe work environment. The authors anticipate that the outcome of this manuscript will have an impact on Indian chromite mining industry that will subsequently bring about improvements in work conditions, develop intervention experiments in occupational health and safety programs.","Occupational health assessment of chromite toxicity among Indian miners Abs: Elevated concentration of hexavalent chromium pollution and contamination has contributed a major health hazard affecting more than 2 lakh mine workers and inhabitants residing in the Sukinda chromite mine of Odisha, India. Despite people suffering from several forms of ill health, physical and mental deformities, constant exposure to toxic wastes and chronic diseases as a result of chromite mining, there is a tragic gap in the availability of 'scientific' studies and data on the health hazards of mining in India. Occupational Safety and Health Administration, Odisha State Pollution Control Board and the Odisha Voluntary Health Association data were used to compile the possible occupational health hazards, hexavalent chromium exposure and diseases among Sukinda chromite mines workers. Studies were reviewed to determine the routes of exposure and possible mechanism of chromium induced carcinogenicity among the workers. Our studies suggest all forms of hexavalent chromium are regarded as carcinogenic to workers however the most important routes of occupational exposure to Cr (VI) are inhalation and dermal contact. This review article outlines the physical, chemical, biological and psychosocial occupational health hazards of chromite mining and associated metallurgical processes to monitor the mining environment as well as the miners exposed to these toxicants to foster a safe work environment. The authors anticipate that the outcome of this manuscript will have an impact on Indian chromite mining industry that will subsequently bring about improvements in work conditions, develop intervention experiments in occupational health and safety programs."
1233576,Blanco-Romero et al. 2011,CAREX Nicaragua and Panama: Worker exposures to carcinogenic substances and pesticides,"This study provides data on numbers of workers exposed at work to selected carcinogens and pesticides in Nicaragua (35 substances) and Panama (31), based on a modification of the CAREX data system. Population censuses provided industry- and sex-specific workforce numbers. The activity- and sex-specific proportions of exposed workers were estimated by experts from governmental agencies, workers' organizations, and employers' representatives. Finally, the numbers of those occupied in each activity/sex category were multiplied by the proportions of those exposed in the same categories, yielding numbers of those exposed in these categories for each agent. The study revealed high proportions (&gt; 9%) of occupationally exposed workers in both countries for solar radiation and diesel engine emissions; environmental tobacco smoke in Panama; and some pesticides in Nicaragua. A high proportion of exposed was found for men for lead (12%), silica dust (10%), and hexavalent chromium (10%) in Panama.","CAREX Nicaragua and Panama: Worker exposures to carcinogenic substances and pesticides Abs: This study provides data on numbers of workers exposed at work to selected carcinogens and pesticides in Nicaragua (35 substances) and Panama (31), based on a modification of the CAREX data system. Population censuses provided industry- and sex-specific workforce numbers. The activity- and sex-specific proportions of exposed workers were estimated by experts from governmental agencies, workers' organizations, and employers' representatives. Finally, the numbers of those occupied in each activity/sex category were multiplied by the proportions of those exposed in the same categories, yielding numbers of those exposed in these categories for each agent. The study revealed high proportions (&gt; 9%) of occupationally exposed workers in both countries for solar radiation and diesel engine emissions; environmental tobacco smoke in Panama; and some pesticides in Nicaragua. A high proportion of exposed was found for men for lead (12%), silica dust (10%), and hexavalent chromium (10%) in Panama."
1233575,Shen and  Wang 1995,Modeling simultaneous hexavalent chromium reduction and phenol degradation by a defined coculture of bacteria,"Based on the kinetics of Cr(VI) reduction by Escherichia coli ATCC 33456 and phenol degradation by Pseudomonas putida DMP-1, a mathematical model is developed to describe simultaneous Cr(VI) reduction and phenol degradation in the coculture of the two species. The developed model incorporates the toxicity effects of Cr(VI) and phenol on phenol degradation and Cr(VI) reduction in the coculture. The model illustrates the inhibitory effects of phenol on Cr(VI) reduction and Cr(VI) toxicity toward phenol degradation. The model also reveals the recoveries of the activities of the repressed bacterial cells with continuous Cr(VI) reduction and phenol degradation in the coculture. The model is capable of predicting simultaneous Cr(VI) reduction and phenol degradation within a broad range of Cr(VI) and phenol concentrations and under an appropriate composition of populations. However, the model simulates lower concentrations of phenol than experimental observations once Cr(VI) is reduced to a low level (&lt;7 mg/L). The model simulation for Cr(VI) also deviates from experimental data when P. putida is outnumbered by E. coli by a ratio of 1:5. (c) 1995 John Wiley &amp; Sons, Inc.","Modeling simultaneous hexavalent chromium reduction and phenol degradation by a defined coculture of bacteria Abs: Based on the kinetics of Cr(VI) reduction by Escherichia coli ATCC 33456 and phenol degradation by Pseudomonas putida DMP-1, a mathematical model is developed to describe simultaneous Cr(VI) reduction and phenol degradation in the coculture of the two species. The developed model incorporates the toxicity effects of Cr(VI) and phenol on phenol degradation and Cr(VI) reduction in the coculture. The model illustrates the inhibitory effects of phenol on Cr(VI) reduction and Cr(VI) toxicity toward phenol degradation. The model also reveals the recoveries of the activities of the repressed bacterial cells with continuous Cr(VI) reduction and phenol degradation in the coculture. The model is capable of predicting simultaneous Cr(VI) reduction and phenol degradation within a broad range of Cr(VI) and phenol concentrations and under an appropriate composition of populations. However, the model simulates lower concentrations of phenol than experimental observations once Cr(VI) is reduced to a low level (&lt;7 mg/L). The model simulation for Cr(VI) also deviates from experimental data when P. putida is outnumbered by E. coli by a ratio of 1:5. (c) 1995 John Wiley &amp; Sons, Inc."
1233574,Shen and  Wang 1994,Modeling hexavalent chromium reduction in Escherichia coli 33456,"A model based on te analysis of the mechanism of enzymatic reactions was developed to characterize the rate and extent of microbial reduction of hexavalent chromium in Escherichia coli 33456. A finite reduction capacity (R(c)) was proposed and incorporated into the enzymatic model to regulate the toxicity effect on cells due to the oxidizing power of Cr(VI). The parameter values were determined by nonlinear least-square analysis using experimental data of anaerobic cultures. The obtained parameters were then used to predict Cr(VI) reduction in aerobic cultures along with a modification term of uncompetitive inhibition from molecular oxygen. The applicability of the developed model was demonstrated through excellent prediction of the results of batch studies conducted over range of initial Cr(VI) concentrations, initial cell densities, and DO levels. A sensitivity analysis revealed that the parameters obtained using the experimental data were unique, and neither change in K(c), the half-velocity constant, at high initial Cr(VI) concentrations nor change in R(c), the reduction capacity, at low initial Cr(VI) concentrations was sensitive to model prediction. (c) 1994 John Wiley &amp; Sons, Inc.","Modeling hexavalent chromium reduction in Escherichia coli 33456 Abs: A model based on te analysis of the mechanism of enzymatic reactions was developed to characterize the rate and extent of microbial reduction of hexavalent chromium in Escherichia coli 33456. A finite reduction capacity (R(c)) was proposed and incorporated into the enzymatic model to regulate the toxicity effect on cells due to the oxidizing power of Cr(VI). The parameter values were determined by nonlinear least-square analysis using experimental data of anaerobic cultures. The obtained parameters were then used to predict Cr(VI) reduction in aerobic cultures along with a modification term of uncompetitive inhibition from molecular oxygen. The applicability of the developed model was demonstrated through excellent prediction of the results of batch studies conducted over range of initial Cr(VI) concentrations, initial cell densities, and DO levels. A sensitivity analysis revealed that the parameters obtained using the experimental data were unique, and neither change in K(c), the half-velocity constant, at high initial Cr(VI) concentrations nor change in R(c), the reduction capacity, at low initial Cr(VI) concentrations was sensitive to model prediction. (c) 1994 John Wiley &amp; Sons, Inc."
1233573,Shrivastava et al. 2005,Effects of dengue virus infection on the spleen of male mice given hexavalent chromium with drinking water,"The present study was undertaken to investigate the effects of dengue virus (DV) infection in male mice given drinking water containing 250 ppm Cr (VI) and the normal control male mice given plain water to drink. On the basis of intake of water in 24 h, the average dose of Cr (VI) in each mouse was 14.8 mg/kg. After 3, 6, and 9 weeks of drinking Cr (VI), a set of five mice from each group were inoculated intracerebrally (ic) with a 1000 x LD(50) (100 times the lethal dose that kills 50% mice) dose of DV, and the effects on the spleen were studied at the fourth and eightth day postinoculation. It was observed that Cr (VI) drinking and DV infection led to reduction in the weight of the spleen, but the peak reduction was seen in Cr (VI)-fed mice infected with DV, being 30, 34, and 61% at 3, 6, and 9 weeks respectively. A similar response was seen with respect to the cytotoxic activity of spleen homogenates, phagocytic activity of macrophages, and the mitogenic response of spleen cells to concanavalin A from different groups of animals, being most marked (58 to 60%) at the ninth week of Cr (VI) drinking. This shows a summation of adverse effects of DV infection in mice preexposed to Cr (VI).","Effects of dengue virus infection on the spleen of male mice given hexavalent chromium with drinking water Abs: The present study was undertaken to investigate the effects of dengue virus (DV) infection in male mice given drinking water containing 250 ppm Cr (VI) and the normal control male mice given plain water to drink. On the basis of intake of water in 24 h, the average dose of Cr (VI) in each mouse was 14.8 mg/kg. After 3, 6, and 9 weeks of drinking Cr (VI), a set of five mice from each group were inoculated intracerebrally (ic) with a 1000 x LD(50) (100 times the lethal dose that kills 50% mice) dose of DV, and the effects on the spleen were studied at the fourth and eightth day postinoculation. It was observed that Cr (VI) drinking and DV infection led to reduction in the weight of the spleen, but the peak reduction was seen in Cr (VI)-fed mice infected with DV, being 30, 34, and 61% at 3, 6, and 9 weeks respectively. A similar response was seen with respect to the cytotoxic activity of spleen homogenates, phagocytic activity of macrophages, and the mitogenic response of spleen cells to concanavalin A from different groups of animals, being most marked (58 to 60%) at the ninth week of Cr (VI) drinking. This shows a summation of adverse effects of DV infection in mice preexposed to Cr (VI)."
1233572,Liu et al. 2010,Bioenergetics and DNA alteration of normal human fibroblasts by hexavalent chromium,"The effects of hexavalent chromium on mitochondria of normal human fibroblasts were investigated through the measurement of oxygen consumption, and its genotoxic effect through the analysis of chromium DNA adducts and oxidative DNA lesions. ROS production was also quantified. Chromium diminished oxygen consumption by cells in a concentration-dependent manner (IC(50)=66±8?M). This effect can be attributed to an alteration in mitochondrial functions, leading to defective glucose catabolism. The Comet assay, performed with and without the lesion-specific enzyme formamidopyrimidine-DNA glycosylase (Fpg), highlighted the extent of oxidative DNA base damage. DNA base damage was induced with low concentrations (0.5-3?M) of Cr(VI), whereas bioenergetic disturbance was only observed at higher concentrations (20-500?M).","Bioenergetics and DNA alteration of normal human fibroblasts by hexavalent chromium Abs: The effects of hexavalent chromium on mitochondria of normal human fibroblasts were investigated through the measurement of oxygen consumption, and its genotoxic effect through the analysis of chromium DNA adducts and oxidative DNA lesions. ROS production was also quantified. Chromium diminished oxygen consumption by cells in a concentration-dependent manner (IC(50)=66±8?M). This effect can be attributed to an alteration in mitochondrial functions, leading to defective glucose catabolism. The Comet assay, performed with and without the lesion-specific enzyme formamidopyrimidine-DNA glycosylase (Fpg), highlighted the extent of oxidative DNA base damage. DNA base damage was induced with low concentrations (0.5-3?M) of Cr(VI), whereas bioenergetic disturbance was only observed at higher concentrations (20-500?M)."
1233571,Mishra and  Mohanty 2008,"Acute toxicity impacts of hexavalent chromium on behavior and histopathology of gill, kidney and liver of the freshwater fish, Channa punctatus (Bloch)","Alteration in behavioral patterns and histopathology of gill, kidney and liver were studied in Channa punctatus, after acute exposure to hexavalent chromium. The 96h LC(50) of chromium salt, potassium dichromate was determined to be 41.75mg/L. The exposed fish displayed erratic swimming and became lethargic. The changes in gills were characterized by epithelial hyperplasia, lamellar fusion, oedema, epithelial lifting, epithelial necrosis and desquamation, aneurism as well as curling of secondary lamellae. Hypertrophy of epithelial cells of renal tubules with reduced lumens, atrophy of the renal tubules, glomeruli contraction in the Bowman's capsules and necrosis of haematopoietic tissues were observed in the trunk kidney of exposed fish. The interrenal cells of the head kidney exhibited distinct hypertrophy and vacuolization. The liver hepatocytes showed cytoplasmic vacuolization with the lateral nuclei arrangement. Hepatocytes atrophy and increase in sinusoidal space were also observed. The result showed that acute chromium toxicity severely affects the vital organs and normal behavior which may be deleterious for fish populations.","Acute toxicity impacts of hexavalent chromium on behavior and histopathology of gill, kidney and liver of the freshwater fish, Channa punctatus (Bloch) Abs: Alteration in behavioral patterns and histopathology of gill, kidney and liver were studied in Channa punctatus, after acute exposure to hexavalent chromium. The 96h LC(50) of chromium salt, potassium dichromate was determined to be 41.75mg/L. The exposed fish displayed erratic swimming and became lethargic. The changes in gills were characterized by epithelial hyperplasia, lamellar fusion, oedema, epithelial lifting, epithelial necrosis and desquamation, aneurism as well as curling of secondary lamellae. Hypertrophy of epithelial cells of renal tubules with reduced lumens, atrophy of the renal tubules, glomeruli contraction in the Bowman's capsules and necrosis of haematopoietic tissues were observed in the trunk kidney of exposed fish. The interrenal cells of the head kidney exhibited distinct hypertrophy and vacuolization. The liver hepatocytes showed cytoplasmic vacuolization with the lateral nuclei arrangement. Hepatocytes atrophy and increase in sinusoidal space were also observed. The result showed that acute chromium toxicity severely affects the vital organs and normal behavior which may be deleterious for fish populations."
1233570,Manerikar et al. 2008,In vitro and in vivo genotoxicity assessment of Cr(VI) using comet assay in earthworm coelomocytes,"Hexavalent chromium is the major terrestrial pollutant released from electroplating industries, tanneries, thermal power plants and sewage. Cr(VI) is reported genotoxicant in vertebrates. Sub-lethal level of Cr(VI) can cause DNA damage. Earthworms are ecologically important soil invertebrates, used for ecotoxicological studies. In present study coelomocytes of Dichogaster curgensis were used for assessing Cr(VI) genotoxicity using single cell gel electrophoresis [(SCGE) i.e. comet assay] following in vitro and in vivo exposures. Cr(VI) produces reactive oxygen species (ROS) in the cellular system, which can be a major cause of DNA damage. Dose dependent DNA damage was observed during in vitro exposure, while in vivo exposure showed increasing DNA damage till 30ppm in terms of arbitrary units and unexpected decrease in arbitrary units at 70 and 100ppm of Cr(VI). It is speculated that the decrease in arbitrary units at higher concentrations might be due to lower DNA mobility, caused by formation of different types of cross-links.","In vitro and in vivo genotoxicity assessment of Cr(VI) using comet assay in earthworm coelomocytes Abs: Hexavalent chromium is the major terrestrial pollutant released from electroplating industries, tanneries, thermal power plants and sewage. Cr(VI) is reported genotoxicant in vertebrates. Sub-lethal level of Cr(VI) can cause DNA damage. Earthworms are ecologically important soil invertebrates, used for ecotoxicological studies. In present study coelomocytes of Dichogaster curgensis were used for assessing Cr(VI) genotoxicity using single cell gel electrophoresis [(SCGE) i.e. comet assay] following in vitro and in vivo exposures. Cr(VI) produces reactive oxygen species (ROS) in the cellular system, which can be a major cause of DNA damage. Dose dependent DNA damage was observed during in vitro exposure, while in vivo exposure showed increasing DNA damage till 30ppm in terms of arbitrary units and unexpected decrease in arbitrary units at 70 and 100ppm of Cr(VI). It is speculated that the decrease in arbitrary units at higher concentrations might be due to lower DNA mobility, caused by formation of different types of cross-links."
1233569,Chandra et al. 2007,Effect of curcumin on chromium-induced oxidative damage in male reproductive system,"Hexavalent chromium, an environmental contaminant, undergoes redox cycling with generation of free radicals inside the biological system. Curcumin, the yellow bioactive component of turmeric has established its antioxidant activities. The present study evaluates possible ameliorating effects of curcumin on potassium dichromate (K(2)Cr(2)O(7)) (hexavalent chromium) induced reproductive toxicity in adult male Sprague-Dawley rats. Three experimental groups, each consisting of eight rats, were treated with 0.4mg K(2)Cr(2)O(7)/kg bw/day, 0.4mg K(2)Cr(2)O(7)/kg bw/day+20mg curcumin/kg bw on every alternate day and 20mg curcumin/kg bw on every alternate day, respectively, for 26 days. Altered testicular histology, reduced sperm count, low testosterone level, decreased accessory sex organs weight, enhanced lipid peroxidation along with reduced SOD and catalase activities were observed following K(2)Cr(2)O(7) exposure while curcumin supplementation along with K(2)Cr(2)O(7) exposure had shown to prevent the altered parameters. The results thus suggest that curcumin may have a protective role against chromium(VI) induced oxidative damage in male reproductive system.","Effect of curcumin on chromium-induced oxidative damage in male reproductive system Abs: Hexavalent chromium, an environmental contaminant, undergoes redox cycling with generation of free radicals inside the biological system. Curcumin, the yellow bioactive component of turmeric has established its antioxidant activities. The present study evaluates possible ameliorating effects of curcumin on potassium dichromate (K(2)Cr(2)O(7)) (hexavalent chromium) induced reproductive toxicity in adult male Sprague-Dawley rats. Three experimental groups, each consisting of eight rats, were treated with 0.4mg K(2)Cr(2)O(7)/kg bw/day, 0.4mg K(2)Cr(2)O(7)/kg bw/day+20mg curcumin/kg bw on every alternate day and 20mg curcumin/kg bw on every alternate day, respectively, for 26 days. Altered testicular histology, reduced sperm count, low testosterone level, decreased accessory sex organs weight, enhanced lipid peroxidation along with reduced SOD and catalase activities were observed following K(2)Cr(2)O(7) exposure while curcumin supplementation along with K(2)Cr(2)O(7) exposure had shown to prevent the altered parameters. The results thus suggest that curcumin may have a protective role against chromium(VI) induced oxidative damage in male reproductive system."
1233568,Zheng et al. 2006,Microcalorimetric investigation of the toxic action of Cr(VI) on the metabolism of Tetrahymena thermophila BF(5) during growth,"Tetrahymena thermophila BF(5) produce heat by metabolism and movement. Using a TAM air isothermal microcalorimeter, the power-time curves of the metabolism of T. thermophila BF(5) during growth were obtained and the action on them by the addition of Cr(VI) were studied. The morphological change with Cr(VI) coexisted and biomass change during the process of T. thermophila BF(5) growth were studied by light microscope. Chromium has been regarded as an essential trace element for life. However, hexavalent chromium is a known carcinogen, mutagen, cytotoxicant and strong oxidizing agent. Cr(VI) of different concentration have different effects on T. thermophila BF(5) growth with the phenomenon of low dose stimulation (0-3×10(-5)molL(-1)) and high dose inhibition (3×10(-5) to 2.4×10(-4)molL(-1)). The relationship between the growth rate constant (k) and c is a typical U-shaped curve, which is a characteristic of hormesis. T. thermophila BF(5) cannot grow at all when the concentration of Cr(VI) is up to 2.4×10(-4)molL(-1). The microscopic observations agree well with the results obtained by means of microcalorimetry. And T. thermophila BF(5) had obviously morphological changes by the addition of Cr(VI).","Microcalorimetric investigation of the toxic action of Cr(VI) on the metabolism of Tetrahymena thermophila BF(5) during growth Abs: Tetrahymena thermophila BF(5) produce heat by metabolism and movement. Using a TAM air isothermal microcalorimeter, the power-time curves of the metabolism of T. thermophila BF(5) during growth were obtained and the action on them by the addition of Cr(VI) were studied. The morphological change with Cr(VI) coexisted and biomass change during the process of T. thermophila BF(5) growth were studied by light microscope. Chromium has been regarded as an essential trace element for life. However, hexavalent chromium is a known carcinogen, mutagen, cytotoxicant and strong oxidizing agent. Cr(VI) of different concentration have different effects on T. thermophila BF(5) growth with the phenomenon of low dose stimulation (0-3×10(-5)molL(-1)) and high dose inhibition (3×10(-5) to 2.4×10(-4)molL(-1)). The relationship between the growth rate constant (k) and c is a typical U-shaped curve, which is a characteristic of hormesis. T. thermophila BF(5) cannot grow at all when the concentration of Cr(VI) is up to 2.4×10(-4)molL(-1). The microscopic observations agree well with the results obtained by means of microcalorimetry. And T. thermophila BF(5) had obviously morphological changes by the addition of Cr(VI)."
1233567,Arzate-Cárdenas and  Martínez-Jerónimo 2011,Age-altered susceptibility in hexavalent chromium-exposed Daphnia schodleri (Anomopoda: Daphniidae): integrated biomarker response implementation,"Daphnia schodleri is a naturally occurring cladoceran in Mexican freshwater bodies and its relative big size and short life cycle allow its use in toxicological bioassays. Generally, life stages at opposite sides of a normal distribution are considered to be the most susceptible and/or sensitive because of several sub-individual level processes, such as ageing, in which antioxidant activity decreases and reactive oxygen species (ROS) cannot be totally neutralized. Most aquatic populations are structured by organisms of different ages, in which physiological and biochemical responses differ (in magnitude) from each other. According to these statements, seven age groups of D. schodleri (0, 3, 5, 7, 14, 21, and 28 d) were exposed to Cr (VI) in both acute and non-lethal bioassays. Results from acute bioassays were used to estimate the chromium LC(50) values for every age group, which ranged from 0.12 to 0.61 mg L(-1), with a normal pattern distribution. Antioxidant enzymatic activity of superoxide dismutase (SOD), catalase (CAT), glutathione peroxidase (GPx), and glutathione reductase (GR) was assessed in organisms exposed to two sublethal Cr(VI) concentrations (0.032 and 0.0064 mg L(-1)). Results showed that neonates' antioxidant activity increased with respect to their controls; nevertheless, the same pattern was not seen in the other age groups. Moreover, GPx activities followed a decreasing pattern with respect to their control groups in organisms 3-d and older. In addition, GR activities were barely modified by chromium exposure of neonates, but not in the other age groups; CAT was only modified in younger daphnids. Once the biomarker responses were normalized, it was possible to observe that enzyme participation differed during the life cycle of this cladoceran and, as a result of their decreasing antioxidant activity, relatively old organisms could have lower capability to deal with pro-oxidant toxicants such as Cr(VI).","Age-altered susceptibility in hexavalent chromium-exposed Daphnia schodleri (Anomopoda: Daphniidae): integrated biomarker response implementation Abs: Daphnia schodleri is a naturally occurring cladoceran in Mexican freshwater bodies and its relative big size and short life cycle allow its use in toxicological bioassays. Generally, life stages at opposite sides of a normal distribution are considered to be the most susceptible and/or sensitive because of several sub-individual level processes, such as ageing, in which antioxidant activity decreases and reactive oxygen species (ROS) cannot be totally neutralized. Most aquatic populations are structured by organisms of different ages, in which physiological and biochemical responses differ (in magnitude) from each other. According to these statements, seven age groups of D. schodleri (0, 3, 5, 7, 14, 21, and 28 d) were exposed to Cr (VI) in both acute and non-lethal bioassays. Results from acute bioassays were used to estimate the chromium LC(50) values for every age group, which ranged from 0.12 to 0.61 mg L(-1), with a normal pattern distribution. Antioxidant enzymatic activity of superoxide dismutase (SOD), catalase (CAT), glutathione peroxidase (GPx), and glutathione reductase (GR) was assessed in organisms exposed to two sublethal Cr(VI) concentrations (0.032 and 0.0064 mg L(-1)). Results showed that neonates' antioxidant activity increased with respect to their controls; nevertheless, the same pattern was not seen in the other age groups. Moreover, GPx activities followed a decreasing pattern with respect to their control groups in organisms 3-d and older. In addition, GR activities were barely modified by chromium exposure of neonates, but not in the other age groups; CAT was only modified in younger daphnids. Once the biomarker responses were normalized, it was possible to observe that enzyme participation differed during the life cycle of this cladoceran and, as a result of their decreasing antioxidant activity, relatively old organisms could have lower capability to deal with pro-oxidant toxicants such as Cr(VI)."
1233564,Myers et al. 2010,"The pro-oxidant chromium(VI) inhibits mitochondrial complex I, complex II, and aconitase in the bronchial epithelium: EPR markers for Fe-S proteins","Hexavalent chromium (Cr(VI)) compounds (e.g., chromates) are strong oxidants that readily enter cells, where they are reduced to reactive Cr species that also facilitate reactive oxygen species generation. Recent studies demonstrated inhibition and oxidation of the thioredoxin system, with greater effects on mitochondrial thioredoxin (Trx2). This implies that Cr(VI)-induced oxidant stress may be especially directed at the mitochondria. Examination of other redox-sensitive mitochondrial functions showed that Cr(VI) treatments that cause Trx2 oxidation in human bronchial epithelial cells also result in pronounced and irreversible inhibition of aconitase, a TCA cycle enzyme that has an iron-sulfur (Fe-S) center that is labile with respect to certain oxidants. The activities of electron transport complexes I and II were also inhibited, whereas complex III was not. Electron paramagnetic resonance (EPR) studies of samples at liquid helium temperature (10K) showed a strong signal at g=1.94 that is consistent with the inhibition of electron flow through complex I and/or II. A signal at g=2.02 was also observed, which is consistent with oxidation of the Fe-S center of aconitase. The g=1.94 signal was particularly intense and remained after extracellular Cr(VI) was removed, whereas the g=2.02 signal declined in intensity after Cr(VI) was removed. A similar inhibition of these activities and analogous EPR findings were noted in bovine airways treated ex vivo with Cr(VI). Overall, the data support the hypothesis that Cr(VI) exposure has deleterious effects on a number of redox-sensitive core mitochondrial proteins. The g=1.94 signal could prove to be an important biomarker for oxidative damage resulting from Cr(VI) exposure. The EPR spectra simultaneously showed signals for Cr(V) and Cr(III), which verify Cr(VI) exposure and its intracellular reductive activation.","The pro-oxidant chromium(VI) inhibits mitochondrial complex I, complex II, and aconitase in the bronchial epithelium: EPR markers for Fe-S proteins Abs: Hexavalent chromium (Cr(VI)) compounds (e.g., chromates) are strong oxidants that readily enter cells, where they are reduced to reactive Cr species that also facilitate reactive oxygen species generation. Recent studies demonstrated inhibition and oxidation of the thioredoxin system, with greater effects on mitochondrial thioredoxin (Trx2). This implies that Cr(VI)-induced oxidant stress may be especially directed at the mitochondria. Examination of other redox-sensitive mitochondrial functions showed that Cr(VI) treatments that cause Trx2 oxidation in human bronchial epithelial cells also result in pronounced and irreversible inhibition of aconitase, a TCA cycle enzyme that has an iron-sulfur (Fe-S) center that is labile with respect to certain oxidants. The activities of electron transport complexes I and II were also inhibited, whereas complex III was not. Electron paramagnetic resonance (EPR) studies of samples at liquid helium temperature (10K) showed a strong signal at g=1.94 that is consistent with the inhibition of electron flow through complex I and/or II. A signal at g=2.02 was also observed, which is consistent with oxidation of the Fe-S center of aconitase. The g=1.94 signal was particularly intense and remained after extracellular Cr(VI) was removed, whereas the g=2.02 signal declined in intensity after Cr(VI) was removed. A similar inhibition of these activities and analogous EPR findings were noted in bovine airways treated ex vivo with Cr(VI). Overall, the data support the hypothesis that Cr(VI) exposure has deleterious effects on a number of redox-sensitive core mitochondrial proteins. The g=1.94 signal could prove to be an important biomarker for oxidative damage resulting from Cr(VI) exposure. The EPR spectra simultaneously showed signals for Cr(V) and Cr(III), which verify Cr(VI) exposure and its intracellular reductive activation."
1233563,Collins et al. 2010,Exposure to hexavalent chromium resulted in significantly higher tissue chromium burden compared with trivalent chromium following similar oral doses to male F344/N rats and female B6C3F1 mice,"In National Toxicology Program 2-year studies, hexavalent chromium [Cr(VI)] administered in drinking water was clearly carcinogenic in male and female rats and mice, resulting in small intestine epithelial neoplasms in mice at a dose equivalent to or within an order of magnitude of human doses that could result from consumption of chromium-contaminated drinking water, assuming that dose scales by body weight(3/4) (body weight raised to the 3/4 power). In contrast, exposure to trivalent chromium [Cr(III)] at much higher concentrations may have been carcinogenic in male rats but was not carcinogenic in mice or female rats. As part of these studies, total chromium was measured in tissues and excreta of additional groups of male rats and female mice. These data were used to infer the uptake and distribution of Cr(VI) because Cr(VI) is reduced to Cr(III) in vivo, and no methods are available to speciate tissue chromium. Comparable external doses resulted in much higher tissue chromium concentrations following exposure to Cr(VI) compared with Cr(III), indicating that a portion of the Cr(VI) escaped gastric reduction and was distributed systemically. Linear or supralinear dose responses of total chromium in tissues were observed following exposure to Cr(VI), indicating that these exposures did not saturate gastric reduction capacity. When Cr(VI) exposure was normalized to ingested dose, chromium concentrations in the liver and glandular stomach were higher in mice, whereas kidney concentrations were higher in rats. In vitro studies demonstrated that Cr(VI), but not Cr(III), is a substrate of the sodium/sulfate cotransporter, providing a partial explanation for the greater absorption of Cr(VI).","Exposure to hexavalent chromium resulted in significantly higher tissue chromium burden compared with trivalent chromium following similar oral doses to male F344/N rats and female B6C3F1 mice Abs: In National Toxicology Program 2-year studies, hexavalent chromium [Cr(VI)] administered in drinking water was clearly carcinogenic in male and female rats and mice, resulting in small intestine epithelial neoplasms in mice at a dose equivalent to or within an order of magnitude of human doses that could result from consumption of chromium-contaminated drinking water, assuming that dose scales by body weight(3/4) (body weight raised to the 3/4 power). In contrast, exposure to trivalent chromium [Cr(III)] at much higher concentrations may have been carcinogenic in male rats but was not carcinogenic in mice or female rats. As part of these studies, total chromium was measured in tissues and excreta of additional groups of male rats and female mice. These data were used to infer the uptake and distribution of Cr(VI) because Cr(VI) is reduced to Cr(III) in vivo, and no methods are available to speciate tissue chromium. Comparable external doses resulted in much higher tissue chromium concentrations following exposure to Cr(VI) compared with Cr(III), indicating that a portion of the Cr(VI) escaped gastric reduction and was distributed systemically. Linear or supralinear dose responses of total chromium in tissues were observed following exposure to Cr(VI), indicating that these exposures did not saturate gastric reduction capacity. When Cr(VI) exposure was normalized to ingested dose, chromium concentrations in the liver and glandular stomach were higher in mice, whereas kidney concentrations were higher in rats. In vitro studies demonstrated that Cr(VI), but not Cr(III), is a substrate of the sodium/sulfate cotransporter, providing a partial explanation for the greater absorption of Cr(VI)."
1233562,Sudha et al. 2011,Biomonitoring of genotoxic effects among shielded manual metal arc welders,"Hexavalent chromium Cr (VI) used in shielded metal arc welding is widely recognized to act as a carcinogen, mutagen and teratogen. The carcinogenic potential of metals is a major issue in defining human health risk from exposure. Hence in the present investigation, 66 welders and 60 control subjects with similar mean ages, smoking prevalences and alcohol consumption were enrolled for DNA damage analysis of buccal cells by micronucleus (MN) and comet assay. Welders showed a significant increase in micronucleated cells compared to controls and a larger mean comet tail length. The current study thus suggested that chronic occupational exposure to Cr (VI) during welding could lead to increased level of DNA damage. Understanding the complexity of the relationshipsbetween exposure, basal DNA damage and MN frequencies requires larger scale studies and application of complementary biomarkers.","Biomonitoring of genotoxic effects among shielded manual metal arc welders Abs: Hexavalent chromium Cr (VI) used in shielded metal arc welding is widely recognized to act as a carcinogen, mutagen and teratogen. The carcinogenic potential of metals is a major issue in defining human health risk from exposure. Hence in the present investigation, 66 welders and 60 control subjects with similar mean ages, smoking prevalences and alcohol consumption were enrolled for DNA damage analysis of buccal cells by micronucleus (MN) and comet assay. Welders showed a significant increase in micronucleated cells compared to controls and a larger mean comet tail length. The current study thus suggested that chronic occupational exposure to Cr (VI) during welding could lead to increased level of DNA damage. Understanding the complexity of the relationshipsbetween exposure, basal DNA damage and MN frequencies requires larger scale studies and application of complementary biomarkers."
1233561,Kaushik et al. 2011,Integrating photobiological hydrogen production with dye-metal bioremoval from simulated textile wastewater,"The study reports production of hydrogen in photobioreactors with free (PBR(Fr)) and immobilized (PBR(Imm)) Nostoc biomass at enhanced and sustained rates. Before running the photobioreactors, effects of different immobilization matrices and cyanobacterial dose on hydrogen production were studied in batch mode. As hydrogen production in the PBRs declined spent biomass from the photobioreactors were collected and utilized further for column biosorption of highly toxic dyes (Reactive Red 198+Crystal Violet) and metals (hexavalent chromium and bivalent cobalt) from simulated textile wastewater. Breakthrough time, adsorption capacity and exhaustion time of the biosorption column were studied. The photobioreactors with free and immobilized cyanobacterium produced hydrogen at average rates of 101 and 151 ?mol/h/mg Chl a, respectively over 15 days, while the adsorption capacity of the spent biomass was up to 1.4 and 0.23 mg/g for metals and 15 and 1.75 mg/g for the dyes, respectively in continuous column mode.","Integrating photobiological hydrogen production with dye-metal bioremoval from simulated textile wastewater Abs: The study reports production of hydrogen in photobioreactors with free (PBR(Fr)) and immobilized (PBR(Imm)) Nostoc biomass at enhanced and sustained rates. Before running the photobioreactors, effects of different immobilization matrices and cyanobacterial dose on hydrogen production were studied in batch mode. As hydrogen production in the PBRs declined spent biomass from the photobioreactors were collected and utilized further for column biosorption of highly toxic dyes (Reactive Red 198+Crystal Violet) and metals (hexavalent chromium and bivalent cobalt) from simulated textile wastewater. Breakthrough time, adsorption capacity and exhaustion time of the biosorption column were studied. The photobioreactors with free and immobilized cyanobacterium produced hydrogen at average rates of 101 and 151 ?mol/h/mg Chl a, respectively over 15 days, while the adsorption capacity of the spent biomass was up to 1.4 and 0.23 mg/g for metals and 15 and 1.75 mg/g for the dyes, respectively in continuous column mode."
1233560,Son et al. 2011,The dual roles of c-Jun NH2-terminal kinase signaling in Cr(VI)-induced apoptosis in JB6 cells,"Occupational exposure to chromium (Cr) compounds has been shown to cause serious toxic and carcinogenic effects. The skin is an important target for the compounds in industrially exposed Cr workers. c-Jun NH(2)-terminal kinase (JNK) regulates cell proliferation, apoptosis, and differentiation. This protein's effects on cellular response depend upon the cell type and stimuli. The mechanisms by which hexavalent chromium (Cr(VI)) leads to apoptosis in the skin are unclear at present. The aim of this study is to examine whether JNK regulates apoptosis in Cr(VI)-exposed mouse JB6 epidermal cells. The present study showed that Cr(VI) induced apoptotic cell death through JNK activation. The blockage of JNK by small interference RNA (si-RNA) transfection suppressed Cr(VI)-induced apoptotic cell death with the concomitant downregulation of antiapoptotic Bcl-2 family proteins, mitochondrial membrane depolarization (??m), caspase activation, and poly (ADP-ribose) polymerase cleavage. However, inhibition of c-Jun expression by si-RNA transfection enhanced cytotoxicity, which corresponded to increasing apoptosis and ??m. This phenomenon is associated with p53 activation caused by increasing reactive oxygen species (ROS) levels because of the downregulation of superoxide dismutase expression in si-c-Jun-transfected cells. Taken together, Cr(VI) induces apoptosis via JNK-mediated signaling, whereas c-Jun activation acts as an inhibitor of apoptotic signaling. Additionally, ROS generated by Cr(VI) is a pivotal regulator of JNK.","The dual roles of c-Jun NH2-terminal kinase signaling in Cr(VI)-induced apoptosis in JB6 cells Abs: Occupational exposure to chromium (Cr) compounds has been shown to cause serious toxic and carcinogenic effects. The skin is an important target for the compounds in industrially exposed Cr workers. c-Jun NH(2)-terminal kinase (JNK) regulates cell proliferation, apoptosis, and differentiation. This protein's effects on cellular response depend upon the cell type and stimuli. The mechanisms by which hexavalent chromium (Cr(VI)) leads to apoptosis in the skin are unclear at present. The aim of this study is to examine whether JNK regulates apoptosis in Cr(VI)-exposed mouse JB6 epidermal cells. The present study showed that Cr(VI) induced apoptotic cell death through JNK activation. The blockage of JNK by small interference RNA (si-RNA) transfection suppressed Cr(VI)-induced apoptotic cell death with the concomitant downregulation of antiapoptotic Bcl-2 family proteins, mitochondrial membrane depolarization (??m), caspase activation, and poly (ADP-ribose) polymerase cleavage. However, inhibition of c-Jun expression by si-RNA transfection enhanced cytotoxicity, which corresponded to increasing apoptosis and ??m. This phenomenon is associated with p53 activation caused by increasing reactive oxygen species (ROS) levels because of the downregulation of superoxide dismutase expression in si-c-Jun-transfected cells. Taken together, Cr(VI) induces apoptosis via JNK-mediated signaling, whereas c-Jun activation acts as an inhibitor of apoptotic signaling. Additionally, ROS generated by Cr(VI) is a pivotal regulator of JNK."
1233559,Soudani et al. 2011,Oxidative stress induced by chromium (VI) in bone of suckling rats,"Exposure to hexavalent chromium Cr(VI) compounds is of concern in many Cr-related industries and their surrounding environments. K(2)Cr(2)O(7) is widely recognized as an animal and human carcinogen, mutagen, and teratogen. The present study investigated the bone maturity of suckling rats whose mothers were treated with K(2)Cr(2)O(7). Experiments were carried out on female Wistar rats given 700 ppm of K(2)Cr(2)O(7) in their drinking water from the 14th day of pregnancy until day 14 after delivery. Exposing dams to K(2)Cr(2)O(7) caused disorders in the bone of their progeny. As corollary to this, malondialdehyde levels increased, while glutathione, a non-protein thiol and vitamin C decreased. Alteration of the antioxidant system in the treated group was also confirmed by the significant decline of superoxide dismutase, catalase, and glutathione peroxidase activities. Furthermore, K(2)Cr(2)O(7) induced changes in bone mineralization, especially calcium and phosphorus levels, which decreased. Whereas, in plasma and urine, they increased and decreased inversely. These results suggest that K(2)Cr(2)O(7) accelerated bone resorption activity. In fact, in treated pups, total tartrate-resistant acid phosphatase, which reflected bone resorption, was enhanced while total alkaline phosphatase, which reflected bone formation, was reduced. The impairment of bone function was corresponded histologically.","Oxidative stress induced by chromium (VI) in bone of suckling rats Abs: Exposure to hexavalent chromium Cr(VI) compounds is of concern in many Cr-related industries and their surrounding environments. K(2)Cr(2)O(7) is widely recognized as an animal and human carcinogen, mutagen, and teratogen. The present study investigated the bone maturity of suckling rats whose mothers were treated with K(2)Cr(2)O(7). Experiments were carried out on female Wistar rats given 700 ppm of K(2)Cr(2)O(7) in their drinking water from the 14th day of pregnancy until day 14 after delivery. Exposing dams to K(2)Cr(2)O(7) caused disorders in the bone of their progeny. As corollary to this, malondialdehyde levels increased, while glutathione, a non-protein thiol and vitamin C decreased. Alteration of the antioxidant system in the treated group was also confirmed by the significant decline of superoxide dismutase, catalase, and glutathione peroxidase activities. Furthermore, K(2)Cr(2)O(7) induced changes in bone mineralization, especially calcium and phosphorus levels, which decreased. Whereas, in plasma and urine, they increased and decreased inversely. These results suggest that K(2)Cr(2)O(7) accelerated bone resorption activity. In fact, in treated pups, total tartrate-resistant acid phosphatase, which reflected bone resorption, was enhanced while total alkaline phosphatase, which reflected bone formation, was reduced. The impairment of bone function was corresponded histologically."
1233558,Byrne et al. 2011,"Control of nanoparticle size, reactivity and magnetic properties during the bioproduction of magnetite by Geobacter sulfurreducens","The bioproduction of nanoscale magnetite by Fe(III)-reducing bacteria offers a potentially tunable, environmentally benign route to magnetic nanoparticle synthesis. Here, we demonstrate that it is possible to control the size of magnetite nanoparticles produced by Geobacter sulfurreducens by adjusting the total biomass introduced at the start of the process. The particles have a narrow size distribution and can be controlled within the range of 10-50 nm. X-ray diffraction analysis indicates that controlled production of a number of different biominerals is possible via this method including goethite, magnetite and siderite, but their formation is strongly dependent upon the rate of Fe(III) reduction and total concentration and rate of Fe(II) produced by the bacteria during the reduction process. Relative cation distributions within the structure of the nanoparticles have been investigated by x-ray magnetic circular dichroism and indicate the presence of a highly reduced surface layer which is not observed when magnetite is produced through abiotic methods. The enhanced Fe(II)-rich surface, combined with small particle size, has important environmental applications such as in the reductive bioremediation of organics, radionuclides and metals. In the case of Cr(VI), as a model high-valence toxic metal, optimized biogenic magnetite is able to reduce and sequester the toxic hexavalent chromium very efficiently to the less harmful trivalent form.","Control of nanoparticle size, reactivity and magnetic properties during the bioproduction of magnetite by Geobacter sulfurreducens Abs: The bioproduction of nanoscale magnetite by Fe(III)-reducing bacteria offers a potentially tunable, environmentally benign route to magnetic nanoparticle synthesis. Here, we demonstrate that it is possible to control the size of magnetite nanoparticles produced by Geobacter sulfurreducens by adjusting the total biomass introduced at the start of the process. The particles have a narrow size distribution and can be controlled within the range of 10-50 nm. X-ray diffraction analysis indicates that controlled production of a number of different biominerals is possible via this method including goethite, magnetite and siderite, but their formation is strongly dependent upon the rate of Fe(III) reduction and total concentration and rate of Fe(II) produced by the bacteria during the reduction process. Relative cation distributions within the structure of the nanoparticles have been investigated by x-ray magnetic circular dichroism and indicate the presence of a highly reduced surface layer which is not observed when magnetite is produced through abiotic methods. The enhanced Fe(II)-rich surface, combined with small particle size, has important environmental applications such as in the reductive bioremediation of organics, radionuclides and metals. In the case of Cr(VI), as a model high-valence toxic metal, optimized biogenic magnetite is able to reduce and sequester the toxic hexavalent chromium very efficiently to the less harmful trivalent form."
1233557,Kathiravan and  Muthukumar 2011,Ultrasound mediated reduction of Cr(VI) using sludge obtained during electrocoagulation,"This study presents the ultrasound mediated reduction of toxic hexavalent chromium (Cr(VI)) into non-toxic trivalent chromium (Cr(III)) using sludge obtained during the electrocoagulation of pharmaceutical wastewater (EC sludge). Experiments were carried out with and without ultrasound to explore its influence. The effect of initial concentration of Cr(VI) (100-200 mg/l), pH (6-8) and EC sludge dosage (5-10 g/l) on Cr(VI) reduction was studied. The morphological and functional group changes of EC sludge due to Cr(VI) reduction were analysed with scanning electron microscopy and Fourier transform infrared, respectively. The reduction rates observed in the presence of ultrasound were found to be higher than the rates observed for without ultrasound. The results concluded that the EC sludge can be successfully used for reduction of Cr(VI) at lower cost.","Ultrasound mediated reduction of Cr(VI) using sludge obtained during electrocoagulation Abs: This study presents the ultrasound mediated reduction of toxic hexavalent chromium (Cr(VI)) into non-toxic trivalent chromium (Cr(III)) using sludge obtained during the electrocoagulation of pharmaceutical wastewater (EC sludge). Experiments were carried out with and without ultrasound to explore its influence. The effect of initial concentration of Cr(VI) (100-200 mg/l), pH (6-8) and EC sludge dosage (5-10 g/l) on Cr(VI) reduction was studied. The morphological and functional group changes of EC sludge due to Cr(VI) reduction were analysed with scanning electron microscopy and Fourier transform infrared, respectively. The reduction rates observed in the presence of ultrasound were found to be higher than the rates observed for without ultrasound. The results concluded that the EC sludge can be successfully used for reduction of Cr(VI) at lower cost."
1233556,Singh et al. 2012,Removal of Cr(VI) by nanoscale zero-valent iron (nZVI) from soil contaminated with tannery wastes,"The illegal disposal of tannery wastes at Rania, Kanpur has resulted in accumulation of hexavalent chromium [Cr(VI)], a toxic heavy metal in soil posing risk to human health and environment. 27 soil samples were collected at various depths from Rania for the assessment of Cr(VI) level in soil. Out of 27 samples, five samples had shown significant level of Cr(VI) with an average concentration of 15.84 mg Kg(-1). Varied doses of nanoscale zero-valent iron (nZVI) were applied on Cr(VI) containing soil samples for remediation of Cr(VI). Results showed that 0.10 g L(-1) nZVI completely reduces Cr(VI) within 120 min following pseudo first order kinetics. Further, to test the efficacy of nZVI in field, soil windrow experiments were performed at the contaminated site. nZVI showed significant Cr(VI) reduction at field also, indicating it an effective tool for managing sites contaminated with Cr(VI).","Removal of Cr(VI) by nanoscale zero-valent iron (nZVI) from soil contaminated with tannery wastes Abs: The illegal disposal of tannery wastes at Rania, Kanpur has resulted in accumulation of hexavalent chromium [Cr(VI)], a toxic heavy metal in soil posing risk to human health and environment. 27 soil samples were collected at various depths from Rania for the assessment of Cr(VI) level in soil. Out of 27 samples, five samples had shown significant level of Cr(VI) with an average concentration of 15.84 mg Kg(-1). Varied doses of nanoscale zero-valent iron (nZVI) were applied on Cr(VI) containing soil samples for remediation of Cr(VI). Results showed that 0.10 g L(-1) nZVI completely reduces Cr(VI) within 120 min following pseudo first order kinetics. Further, to test the efficacy of nZVI in field, soil windrow experiments were performed at the contaminated site. nZVI showed significant Cr(VI) reduction at field also, indicating it an effective tool for managing sites contaminated with Cr(VI)."
1233555,Ray and  Sarkar 2012,Light and scanning electron microscopic studies on chromium-induced anemia in a murine model,"Blood hemoglobin level, hematocrit value and erythrocyte count were reduced by 17.5, 17.4 and 15.9%, respectively, as compared to the controls, in Swiss mice treated intraperitoneally with hexavalent chromium (4 mg of potassium dichromate per Kg for 5 day per week) for 2 weeks. Echinocytic transformation of 33.8% erythrocytes, as revealed by both light and scanning electron microscopy, indicated the anemia to be hemolytic in nature. Leucopenia was apparent after 2 weeks (mean leucocyte count: 4.91 thousand c mm(-1)), but not 1 week of treatment (mean count: 6.43 thousand c mm(-1)), However, cytochemical studies indicated that chromium did not interfere with iron utilization for hemoglobin synthesis and also, did not cause denaturation of already synthesized hemoglobin. The study hints to the necessity of periodic monitoring of blood in workers of chromium-dependent tanneries of Kolkata, India.","Light and scanning electron microscopic studies on chromium-induced anemia in a murine model Abs: Blood hemoglobin level, hematocrit value and erythrocyte count were reduced by 17.5, 17.4 and 15.9%, respectively, as compared to the controls, in Swiss mice treated intraperitoneally with hexavalent chromium (4 mg of potassium dichromate per Kg for 5 day per week) for 2 weeks. Echinocytic transformation of 33.8% erythrocytes, as revealed by both light and scanning electron microscopy, indicated the anemia to be hemolytic in nature. Leucopenia was apparent after 2 weeks (mean leucocyte count: 4.91 thousand c mm(-1)), but not 1 week of treatment (mean count: 6.43 thousand c mm(-1)), However, cytochemical studies indicated that chromium did not interfere with iron utilization for hemoglobin synthesis and also, did not cause denaturation of already synthesized hemoglobin. The study hints to the necessity of periodic monitoring of blood in workers of chromium-dependent tanneries of Kolkata, India."
1233554,Francisco et al. 2011,Metal-induced phosphate extracellular nanoparticulate formation in Ochrobactrum tritici 5bvl1,"Hexavalent chromium (Cr(VI)) is a toxic environmental contaminant which detoxification consists in reduction to Cr(III). In this work, the Cr(VI)-resistant and reducing Ochrobactrum tritici 5bvl1 produced phosphate nanoparticles upon exposure to Cr(VI) and Fe(III), effectively removing chromium from solution. Under Cr(VI) stress, higher siderophore production by strain 5bvl1 was observed. Cr(VI) toxicity was decreased in presence of Fe(III), increasing the growth and Cr(VI)-reduction rates in cell cultures, lowering the amount of morphologically compromised cells and promoting chromium immobilization as insoluble extracellular phosphate complexes. The formation of phosphate nanoparticles increased with Cr(VI) and Fe(III) concentrations and was also stimulated by Ni(II). Under these experimental conditions, nanoparticle formation occurred together with enhanced inorganic phosphate consumption by cells and increased polyphosphate kinase (PPK) activity. NMR analysis of the particles showed the presence of both polyphosphate and phosphonate together with orthophosphate, and FT-IR supported these results, also showing evidences of Cr(III) coordination. This work demonstrated that O. tritici 5bvl1 possesses protection mechanisms against chromium toxicity other than the presence of the Cr(VI) pump and SOD related enzymes previously described. Future assessment of the molecular regulation of production of these nanoparticles will open new perspectives for remediation of metal contaminated environments.","Metal-induced phosphate extracellular nanoparticulate formation in Ochrobactrum tritici 5bvl1 Abs: Hexavalent chromium (Cr(VI)) is a toxic environmental contaminant which detoxification consists in reduction to Cr(III). In this work, the Cr(VI)-resistant and reducing Ochrobactrum tritici 5bvl1 produced phosphate nanoparticles upon exposure to Cr(VI) and Fe(III), effectively removing chromium from solution. Under Cr(VI) stress, higher siderophore production by strain 5bvl1 was observed. Cr(VI) toxicity was decreased in presence of Fe(III), increasing the growth and Cr(VI)-reduction rates in cell cultures, lowering the amount of morphologically compromised cells and promoting chromium immobilization as insoluble extracellular phosphate complexes. The formation of phosphate nanoparticles increased with Cr(VI) and Fe(III) concentrations and was also stimulated by Ni(II). Under these experimental conditions, nanoparticle formation occurred together with enhanced inorganic phosphate consumption by cells and increased polyphosphate kinase (PPK) activity. NMR analysis of the particles showed the presence of both polyphosphate and phosphonate together with orthophosphate, and FT-IR supported these results, also showing evidences of Cr(III) coordination. This work demonstrated that O. tritici 5bvl1 possesses protection mechanisms against chromium toxicity other than the presence of the Cr(VI) pump and SOD related enzymes previously described. Future assessment of the molecular regulation of production of these nanoparticles will open new perspectives for remediation of metal contaminated environments."
1233553,Lupescu et al. 2012,Hexavalent chromium-induced erythrocyte membrane phospholipid asymmetry,"Hexavalent (VI) chromium is a global contaminant with cytotoxic activity. Chromium (VI) induces oxidative stress, inflammation, cell proliferation, malignant transformation and may trigger carcinogenesis and at the same time apoptosis. The toxic effects of chromium (VI) at least partially result from mitochondrial injury and DNA damage. Erythrocytes lack mitochondria and nuclei but may experience an apoptosis-like suicidal cell death, i.e. eryptosis, which is characterized by cell shrinkage and cell membrane scrambling with phosphatidylserine exposure at the cell surface. Eryptosis may result from increase of cytosolic Ca(2+) activity, ATP depletion and/or ceramide formation. The present study explored, whether chromium (VI) triggers eryptosis. Fluo-3-fluorescence was employed to determine cytosolic Ca(2+)-concentration, forward scatter to estimate cell volume, binding of fluorescent annexin V to detect phosphatidylserine exposure, hemoglobin concentration in the supernatant to quantify hemolysis, luciferin-luciferase to determine cytosolic ATP concentration and fluorescent anti-ceramide antibodies to uncover ceramide formation. A 48 h exposure to chromium (VI) (?10 ?M) significantly increased cytosolic Ca(2+)-concentration, decreased ATP concentration (20 ?M), decreased forward scatter, increased annexin V-binding and increased (albeit to a much smaller extent) hemolysis. Chromium (VI) did not significantly modify ceramide formation. The effect of 20 ?M chromium (VI) on annexin V binding was partially reversed in the nominal absence of Ca(2+). The present observations disclose a novel effect of chromium (VI), i.e. Ca(2+) entry and cytosolic ATP depletion in erythrocytes, effects resulting in eryptosis with cell shrinkage and cell membrane scrambling.","Hexavalent chromium-induced erythrocyte membrane phospholipid asymmetry Abs: Hexavalent (VI) chromium is a global contaminant with cytotoxic activity. Chromium (VI) induces oxidative stress, inflammation, cell proliferation, malignant transformation and may trigger carcinogenesis and at the same time apoptosis. The toxic effects of chromium (VI) at least partially result from mitochondrial injury and DNA damage. Erythrocytes lack mitochondria and nuclei but may experience an apoptosis-like suicidal cell death, i.e. eryptosis, which is characterized by cell shrinkage and cell membrane scrambling with phosphatidylserine exposure at the cell surface. Eryptosis may result from increase of cytosolic Ca(2+) activity, ATP depletion and/or ceramide formation. The present study explored, whether chromium (VI) triggers eryptosis. Fluo-3-fluorescence was employed to determine cytosolic Ca(2+)-concentration, forward scatter to estimate cell volume, binding of fluorescent annexin V to detect phosphatidylserine exposure, hemoglobin concentration in the supernatant to quantify hemolysis, luciferin-luciferase to determine cytosolic ATP concentration and fluorescent anti-ceramide antibodies to uncover ceramide formation. A 48 h exposure to chromium (VI) (?10 ?M) significantly increased cytosolic Ca(2+)-concentration, decreased ATP concentration (20 ?M), decreased forward scatter, increased annexin V-binding and increased (albeit to a much smaller extent) hemolysis. Chromium (VI) did not significantly modify ceramide formation. The effect of 20 ?M chromium (VI) on annexin V binding was partially reversed in the nominal absence of Ca(2+). The present observations disclose a novel effect of chromium (VI), i.e. Ca(2+) entry and cytosolic ATP depletion in erythrocytes, effects resulting in eryptosis with cell shrinkage and cell membrane scrambling."
1233552,Eleftheriou et al. 2012,"Effects of hexavalent chromium on microtubule organization, ER distribution and callose deposition in root tip cells of Allium cepa L","The subcellular targets of hexavalent chromium [Cr(VI)] were examined in Allium cepa root tips with confocal laser scanning microscopy. Cr(VI) exerted dose- and time-dependent negative effects on root growth rate, the mitotic index and microtubule (MT) organization during cell division cycle. Interphase MTs were more resistant than the mitotic ones, but when affected they were shorter, sparse and disoriented. The preprophase band of MTs became poorly organized, branched or with fragmented MTs, whilst neither a perinuclear array nor a prophase spindle was formed. Metaphase spindles converged to eccentric mini poles or consisted of dissimilar halves and were unable to correctly orient the chromosomes. Anaphase spindles were less disturbed, but chromatids failed to separate; neither did they move to the poles. At telophase, projecting, lagging or bridging chromosomes and micronuclei also occurred. Phragmoplasts were unilaterally developed, split, located at unexpected sites and frequently dissociated from the branched and misaligned cell plates. Chromosomal aberrations were directly correlated with MT disturbance. The morphology and distribution of endoplasmic reticulum was severely perturbed and presumably contributed to MT disassembly. Heavy callose apposition was also induced by Cr(VI), maybe in the context of a cellular defence reaction. Results indicate that MTs are one of the main subcellular targets of Cr(VI), MT impairment underlies chromosomal and mitotic aberrations, and MTs may constitute a reliable biomonitoring system for Cr(VI) toxicity in plants.","Effects of hexavalent chromium on microtubule organization, ER distribution and callose deposition in root tip cells of Allium cepa L Abs: The subcellular targets of hexavalent chromium [Cr(VI)] were examined in Allium cepa root tips with confocal laser scanning microscopy. Cr(VI) exerted dose- and time-dependent negative effects on root growth rate, the mitotic index and microtubule (MT) organization during cell division cycle. Interphase MTs were more resistant than the mitotic ones, but when affected they were shorter, sparse and disoriented. The preprophase band of MTs became poorly organized, branched or with fragmented MTs, whilst neither a perinuclear array nor a prophase spindle was formed. Metaphase spindles converged to eccentric mini poles or consisted of dissimilar halves and were unable to correctly orient the chromosomes. Anaphase spindles were less disturbed, but chromatids failed to separate; neither did they move to the poles. At telophase, projecting, lagging or bridging chromosomes and micronuclei also occurred. Phragmoplasts were unilaterally developed, split, located at unexpected sites and frequently dissociated from the branched and misaligned cell plates. Chromosomal aberrations were directly correlated with MT disturbance. The morphology and distribution of endoplasmic reticulum was severely perturbed and presumably contributed to MT disassembly. Heavy callose apposition was also induced by Cr(VI), maybe in the context of a cellular defence reaction. Results indicate that MTs are one of the main subcellular targets of Cr(VI), MT impairment underlies chromosomal and mitotic aberrations, and MTs may constitute a reliable biomonitoring system for Cr(VI) toxicity in plants."
1233551,Fibbi et al. 2012,"Distribution and mass balance of hexavalent and trivalent chromium in a subsurface, horizontal flow (SF-h) constructed wetland operating as post-treatment of textile wastewater for water reuse","In this study, during a two-year period, we investigated the fate of hexavalent and trivalent chromium in a full-scale subsurface horizontal flow constructed wetland planted with Phragmites australis. The reed bed operated as post-treatment of the effluent wastewater from an activated sludge plant serving the textile industrial district and the city of Prato (Italy). Chromium speciation was performed in influent and effluent wastewater and in water-suspended solids, at different depths and distances from the inlet; plants were also analyzed for total chromium along the same longitudinal profile. Removals of hexavalent and trivalent chromium equal to 72% and 26%, respectively were achieved. The mean hexavalent chromium outlet concentration was 1.6 ± 0.9 ?g l(-1) and complied with the Italian legal limits for water reuse. Chromium in water-suspended solids was in the trivalent form, thus indicating that its removal from wastewater was obtained by the reduction of hexavalent chromium to the trivalent form, followed by accumulation of the latter inside the reed bed. Chromium in water-suspended solids was significantly affected by the distance from the inlet. Chromium concentrations in the different plant organs followed the same trend of suspended solids along the longitudinal profile and were much lower than those found in the solid material, evidencing a low metal accumulation in P. australis.","Distribution and mass balance of hexavalent and trivalent chromium in a subsurface, horizontal flow (SF-h) constructed wetland operating as post-treatment of textile wastewater for water reuse Abs: In this study, during a two-year period, we investigated the fate of hexavalent and trivalent chromium in a full-scale subsurface horizontal flow constructed wetland planted with Phragmites australis. The reed bed operated as post-treatment of the effluent wastewater from an activated sludge plant serving the textile industrial district and the city of Prato (Italy). Chromium speciation was performed in influent and effluent wastewater and in water-suspended solids, at different depths and distances from the inlet; plants were also analyzed for total chromium along the same longitudinal profile. Removals of hexavalent and trivalent chromium equal to 72% and 26%, respectively were achieved. The mean hexavalent chromium outlet concentration was 1.6 ± 0.9 ?g l(-1) and complied with the Italian legal limits for water reuse. Chromium in water-suspended solids was in the trivalent form, thus indicating that its removal from wastewater was obtained by the reduction of hexavalent chromium to the trivalent form, followed by accumulation of the latter inside the reed bed. Chromium in water-suspended solids was significantly affected by the distance from the inlet. Chromium concentrations in the different plant organs followed the same trend of suspended solids along the longitudinal profile and were much lower than those found in the solid material, evidencing a low metal accumulation in P. australis."
1233550,Gangwar et al. 2011,Kinetin supplementation modifies chromium (VI) induced alterations in growth and ammonium assimilation in pea seedlings,"In the present study, impact of kinetin (KN; 10 and 100 ?M) supplementation on growth, ammonium (NH(4)(+)) assimilation and antioxidant system in pea under hexavalent chromium toxicity (Cr VI; 50, 100 and 250 ?M) was investigated. Chromium decreased growth, protein, and nitrogen, and activity of glutamine synthetase (GS) and glutamate synthase (GOGAT) while it increased NH(4)(+) content and activity of glutamate dehydrogenase (GDH). Kinetin at 100 ?M decreased growth and NH(4)(+) assimilation, and together with Cr, it increased Cr toxicity. Chromium and 100 ?M KN increased superoxide dismutase (SOD) and ascorbate peroxidase (APX) activities while decreasing activities of catalase (CAT), glutathione reductase (GR) and dehydroascorbate reductase (DHAR). Ascorbate and glutathione levels were decreased by Cr and 100 ?M KN. In contrast, supplementation of 10 ?M KN under Cr (VI) toxicity, protected NH(4)(+) assimilation and promoted growth of pea by increasing levels of some of the antioxidants i.e., CAT, GR, DHAR, ascorbate and glutathione. Results showed that 10 ?M KN increases Cr tolerance while 100 ?M KN exhibited opposite responses. These results could contribute to an understanding of the mechanisms of KN-mediated dual influence on metal tolerance in crop plants.","Kinetin supplementation modifies chromium (VI) induced alterations in growth and ammonium assimilation in pea seedlings Abs: In the present study, impact of kinetin (KN; 10 and 100 ?M) supplementation on growth, ammonium (NH(4)(+)) assimilation and antioxidant system in pea under hexavalent chromium toxicity (Cr VI; 50, 100 and 250 ?M) was investigated. Chromium decreased growth, protein, and nitrogen, and activity of glutamine synthetase (GS) and glutamate synthase (GOGAT) while it increased NH(4)(+) content and activity of glutamate dehydrogenase (GDH). Kinetin at 100 ?M decreased growth and NH(4)(+) assimilation, and together with Cr, it increased Cr toxicity. Chromium and 100 ?M KN increased superoxide dismutase (SOD) and ascorbate peroxidase (APX) activities while decreasing activities of catalase (CAT), glutathione reductase (GR) and dehydroascorbate reductase (DHAR). Ascorbate and glutathione levels were decreased by Cr and 100 ?M KN. In contrast, supplementation of 10 ?M KN under Cr (VI) toxicity, protected NH(4)(+) assimilation and promoted growth of pea by increasing levels of some of the antioxidants i.e., CAT, GR, DHAR, ascorbate and glutathione. Results showed that 10 ?M KN increases Cr tolerance while 100 ?M KN exhibited opposite responses. These results could contribute to an understanding of the mechanisms of KN-mediated dual influence on metal tolerance in crop plants."
1233549,Urbano et al. 2012,Molecular and cellular mechanisms of hexavalent chromium-induced lung cancer: An updated perspective,"For over a century, chromium (Cr) has found widespread industrial and commercial use, namely as a pigment, in the production of stainless steel and in chrome plating. The adverse health effects to the skin and respiratory tract of prolonged exposure to Cr have been known or suspected for a long time, but it was much more recently that the toxicity of this element was unequivocally attributed to its hexavalent state. Based on the combined results of extensive epidemiological studies, animal carcinogenicity studies and several types of other relevant data, authoritative regulatory agencies have found sufficient evidence to classify hexavalent chromium [Cr(VI)] compounds as encountered in the chromate production, chromate pigment production and chromium plating industries as carcinogenic to humans. Crucial for the development of novel strategies to prevent, detect and/or treat Cr(VI)-induced cancers is a detailed knowledge of the molecular and cellular mechanisms underlying these pathologies. Unfortunately, in spite of a considerable research effort, crucial facets of these mechanisms remain essentially unknown. This review is intended to provide a concise, integrated and critical perspective of the current state of knowledge concerning multiple aspects of Cr(VI) carcinogenesis. It will present recent theories of Cr(VI)-induced carcinogenesis and will include aspects not traditionally covered in other reviews, such as the possible involvement of the energy metabolism in this process. A brief discussion on the models that have been used in the studies of Cr(VI)-induced carcinogenicity will also be included, due to the impact of this parameter on the relevance of the results obtained.","Molecular and cellular mechanisms of hexavalent chromium-induced lung cancer: An updated perspective Abs: For over a century, chromium (Cr) has found widespread industrial and commercial use, namely as a pigment, in the production of stainless steel and in chrome plating. The adverse health effects to the skin and respiratory tract of prolonged exposure to Cr have been known or suspected for a long time, but it was much more recently that the toxicity of this element was unequivocally attributed to its hexavalent state. Based on the combined results of extensive epidemiological studies, animal carcinogenicity studies and several types of other relevant data, authoritative regulatory agencies have found sufficient evidence to classify hexavalent chromium [Cr(VI)] compounds as encountered in the chromate production, chromate pigment production and chromium plating industries as carcinogenic to humans. Crucial for the development of novel strategies to prevent, detect and/or treat Cr(VI)-induced cancers is a detailed knowledge of the molecular and cellular mechanisms underlying these pathologies. Unfortunately, in spite of a considerable research effort, crucial facets of these mechanisms remain essentially unknown. This review is intended to provide a concise, integrated and critical perspective of the current state of knowledge concerning multiple aspects of Cr(VI) carcinogenesis. It will present recent theories of Cr(VI)-induced carcinogenesis and will include aspects not traditionally covered in other reviews, such as the possible involvement of the energy metabolism in this process. A brief discussion on the models that have been used in the studies of Cr(VI)-induced carcinogenicity will also be included, due to the impact of this parameter on the relevance of the results obtained."
1233548,Garg et al. 2012,Strategies for chromium bioremediation of tannery effluent,"Bioremediation offers the possibility of using living organisms (bacteria, fungi, algae,or plants), but primarily microorganisms, to degrade or remove environmental contaminants, and transform them into nontoxic or less-toxic forms. The major advantages of bioremediation over conventional physicochemical and biological treatment methods include low cost, good efficiency, minimization of chemicals, reduced quantity of secondary sludge, regeneration of cell biomass, and the possibility of recover-ing pollutant metals. Leather industries, which extensively employ chromium compounds in the tanning process, discharge spent-chromium-laden effluent into nearby water bodies. Worldwide, chromium is known to be one of the most common inorganic contaminants of groundwater at pollutant hazardous sites. Hexavalent chromium poses a health risk to all forms of life. Bioremediation of chromium extant in tannery waste involves different strategies that include biosorption, bioaccumulation,bioreduction, and immobilization of biomaterial(s). Biosorption is a nondirected physiochemical interaction that occurs between metal species and the cellular components of biological species. It is metabolism-dependent when living biomass is employed, and metabolism-independent in dead cell biomass. Dead cell biomass is much more effective than living cell biomass at biosorping heavy metals, including chromium. Bioaccumulation is a metabolically active process in living organisms that works through adsorption, intracellular accumulation, and bioprecipitation mechanisms. In bioreduction processes, microorganisms alter the oxidation/reduction state of toxic metals through direct or indirect biological and chemical process(es).Bioreduction of Cr6+ to Cr3+ not only decreases the chromium toxicity to living organisms, but also helps precipitate chromium at a neutral pH for further physical removal,thus offering promise as a bioremediation strategy. However, biosorption, bioaccumulation, and bioreduction methods that rely on free cells for bioremediation suffer from Cr6 toxicity, and cell damage. Therefore, immobilization of microbial cell biomass enhances bioremediation and renders industrial bioremediation processes more economically viable from reduced free-cells toxicity, easier separation of biosorbents from the tannery effluent, ability to achieve multiple biosorption cycles, and desorption (elution) of metal(s) from matrices for reuse. Thus, microbial bioremediation can be a cost competitive strategy and beneficial bioresource for removing many hazardous contaminants from tannery and other industrial wastes.","Strategies for chromium bioremediation of tannery effluent Abs: Bioremediation offers the possibility of using living organisms (bacteria, fungi, algae,or plants), but primarily microorganisms, to degrade or remove environmental contaminants, and transform them into nontoxic or less-toxic forms. The major advantages of bioremediation over conventional physicochemical and biological treatment methods include low cost, good efficiency, minimization of chemicals, reduced quantity of secondary sludge, regeneration of cell biomass, and the possibility of recover-ing pollutant metals. Leather industries, which extensively employ chromium compounds in the tanning process, discharge spent-chromium-laden effluent into nearby water bodies. Worldwide, chromium is known to be one of the most common inorganic contaminants of groundwater at pollutant hazardous sites. Hexavalent chromium poses a health risk to all forms of life. Bioremediation of chromium extant in tannery waste involves different strategies that include biosorption, bioaccumulation,bioreduction, and immobilization of biomaterial(s). Biosorption is a nondirected physiochemical interaction that occurs between metal species and the cellular components of biological species. It is metabolism-dependent when living biomass is employed, and metabolism-independent in dead cell biomass. Dead cell biomass is much more effective than living cell biomass at biosorping heavy metals, including chromium. Bioaccumulation is a metabolically active process in living organisms that works through adsorption, intracellular accumulation, and bioprecipitation mechanisms. In bioreduction processes, microorganisms alter the oxidation/reduction state of toxic metals through direct or indirect biological and chemical process(es).Bioreduction of Cr6+ to Cr3+ not only decreases the chromium toxicity to living organisms, but also helps precipitate chromium at a neutral pH for further physical removal,thus offering promise as a bioremediation strategy. However, biosorption, bioaccumulation, and bioreduction methods that rely on free cells for bioremediation suffer from Cr6 toxicity, and cell damage. Therefore, immobilization of microbial cell biomass enhances bioremediation and renders industrial bioremediation processes more economically viable from reduced free-cells toxicity, easier separation of biosorbents from the tannery effluent, ability to achieve multiple biosorption cycles, and desorption (elution) of metal(s) from matrices for reuse. Thus, microbial bioremediation can be a cost competitive strategy and beneficial bioresource for removing many hazardous contaminants from tannery and other industrial wastes."
1233547,Wise and  Wise 2012,Chromium and genomic stability,"Many metals serve as micronutrients which protect against genomic instability. Chromium is most abundant in its trivalent and hexavalent forms. Trivalent chromium has historically been considered an essential element, though recent data indicate that while it can have pharmacological effects and value, it is not essential. There is no data indicating that trivalent chromium promotes genomic stability and, instead may promote genomic instability. Hexavalent chromium is widely accepted as highly toxic and carcinogenic with no nutritional value. Recent data indicate that it causes genomic instability and also has no role in promoting genomic stability.","Chromium and genomic stability Abs: Many metals serve as micronutrients which protect against genomic instability. Chromium is most abundant in its trivalent and hexavalent forms. Trivalent chromium has historically been considered an essential element, though recent data indicate that while it can have pharmacological effects and value, it is not essential. There is no data indicating that trivalent chromium promotes genomic stability and, instead may promote genomic instability. Hexavalent chromium is widely accepted as highly toxic and carcinogenic with no nutritional value. Recent data indicate that it causes genomic instability and also has no role in promoting genomic stability."
1233546,Zuo et al. 2012,Hexavalent chromium Cr(VI) up-regulates COX-2 expression through an NF?B/c-Jun/AP-1-dependent pathway,"<strong>BACKGROUND: </strong>Hexavalent chromium [Cr(VI)] is recognized as a human carcinogen via inhalation. However, the molecular mechanisms by which Cr(VI) causes cancers are not well understood.<br /><br /><strong>OBJECTIVES: </strong>We evaluated cyclooxygenase-2 (COX-2) expression and the signaling pathway leading to this induction due to Cr(VI) exposure in cultured cells.<br /><br /><strong>METHODS: </strong>We used the luciferase reporter assay and Western blotting to determine COX-2 induction by Cr(VI). We used dominant negative mutant, genetic knockout, gene knockdown, and chromatin immunoprecipitation approaches to elucidate the signaling pathway leading to COX-2 induction.<br /><br /><strong>RESULTS: </strong>We found that Cr(VI) exposure induced COX-2 expression in both normal human bronchial epithelial cells and mouse embryonic fibroblasts in a concentration- and time-dependent manner. Deletion of IKK? [inhibitor of transcription factor NF?B (I?B) kinase ?; an upstream kinase responsible for nuclear factor ?B (NF?B) activation] or overexpression of TAM67 (a dominant-negative mutant of c-Jun) dramatically inhibited the COX-2 induction due to Cr(VI), suggesting that both NF?B and c-Jun/AP-1 pathways were required for Cr(VI)-induced COX-2 expression. Our results show that p65 and c-Jun are two major components involved in NF?B and AP-1 activation, respectively. Moreover, our studies suggest crosstalk between NF?B and c-Jun/AP-1 pathways in cellular response to Cr(VI) exposure for COX-2 induction.<br /><br /><strong>CONCLUSION: </strong>We demonstrate for the first time that Cr(VI) is able to induce COX-2 expression via an NF?B/c-Jun/AP-1-dependent pathway. Our results provide novel insight into the molecular mechanisms linking Cr(VI) exposure to lung inflammation and carcinogenesis.","Hexavalent chromium Cr(VI) up-regulates COX-2 expression through an NF?B/c-Jun/AP-1-dependent pathway Abs: <strong>BACKGROUND: </strong>Hexavalent chromium [Cr(VI)] is recognized as a human carcinogen via inhalation. However, the molecular mechanisms by which Cr(VI) causes cancers are not well understood.<br /><br /><strong>OBJECTIVES: </strong>We evaluated cyclooxygenase-2 (COX-2) expression and the signaling pathway leading to this induction due to Cr(VI) exposure in cultured cells.<br /><br /><strong>METHODS: </strong>We used the luciferase reporter assay and Western blotting to determine COX-2 induction by Cr(VI). We used dominant negative mutant, genetic knockout, gene knockdown, and chromatin immunoprecipitation approaches to elucidate the signaling pathway leading to COX-2 induction.<br /><br /><strong>RESULTS: </strong>We found that Cr(VI) exposure induced COX-2 expression in both normal human bronchial epithelial cells and mouse embryonic fibroblasts in a concentration- and time-dependent manner. Deletion of IKK? [inhibitor of transcription factor NF?B (I?B) kinase ?; an upstream kinase responsible for nuclear factor ?B (NF?B) activation] or overexpression of TAM67 (a dominant-negative mutant of c-Jun) dramatically inhibited the COX-2 induction due to Cr(VI), suggesting that both NF?B and c-Jun/AP-1 pathways were required for Cr(VI)-induced COX-2 expression. Our results show that p65 and c-Jun are two major components involved in NF?B and AP-1 activation, respectively. Moreover, our studies suggest crosstalk between NF?B and c-Jun/AP-1 pathways in cellular response to Cr(VI) exposure for COX-2 induction.<br /><br /><strong>CONCLUSION: </strong>We demonstrate for the first time that Cr(VI) is able to induce COX-2 expression via an NF?B/c-Jun/AP-1-dependent pathway. Our results provide novel insight into the molecular mechanisms linking Cr(VI) exposure to lung inflammation and carcinogenesis."
1233545,Pandikumar and  Ramaraj 2012,Titanium dioxide-gold nanocomposite materials embedded in silicate sol-gel film catalyst for simultaneous photodegradation of hexavalent chromium and methylene blue,Aminosilicate sol-gel supported titanium dioxide-gold (EDAS/(TiO(2)-Au)(nps)) nanocomposite materials were synthesized by simple deposition-precipitation method and characterized. The photocatalytic oxidation and reduction activity of the EDAS/(TiO(2)-Au)(nps) film was evaluated using hexavalent chromium (Cr(VI)) and methylene blue (MB) dye under irradiation. The photocatalytic reduction of Cr(VI) to Cr(III) was studied in the presence of hole scavengers such as oxalic acid (OA) and methylene blue (MB). The photocatalytic degradation of MB was investigated in the presence and absence of Cr(VI). Presence of Au(nps) on the (TiO(2))(nps) surface and its dispersion in the silicate sol-gel film (EDAS/(TiO(2)-Au)(nps)) improved the photocatalytic reduction of Cr(VI) and oxidation of MB due to the effective interfacial electron transfer from the conduction band of the TiO(2) to Au(nps) by minimizing the charge recombination process when compared to the TiO(2) and (TiO(2)-Au)(nps) in the absence of EDAS. The EDAS/(TiO(2)-Au)(nps) nanocomposite materials provided beneficial role in the environmental remediation and purification process through synergistic photocatalytic activity by an advanced oxidation-reduction processes.,Titanium dioxide-gold nanocomposite materials embedded in silicate sol-gel film catalyst for simultaneous photodegradation of hexavalent chromium and methylene blue Abs: Aminosilicate sol-gel supported titanium dioxide-gold (EDAS/(TiO(2)-Au)(nps)) nanocomposite materials were synthesized by simple deposition-precipitation method and characterized. The photocatalytic oxidation and reduction activity of the EDAS/(TiO(2)-Au)(nps) film was evaluated using hexavalent chromium (Cr(VI)) and methylene blue (MB) dye under irradiation. The photocatalytic reduction of Cr(VI) to Cr(III) was studied in the presence of hole scavengers such as oxalic acid (OA) and methylene blue (MB). The photocatalytic degradation of MB was investigated in the presence and absence of Cr(VI). Presence of Au(nps) on the (TiO(2))(nps) surface and its dispersion in the silicate sol-gel film (EDAS/(TiO(2)-Au)(nps)) improved the photocatalytic reduction of Cr(VI) and oxidation of MB due to the effective interfacial electron transfer from the conduction band of the TiO(2) to Au(nps) by minimizing the charge recombination process when compared to the TiO(2) and (TiO(2)-Au)(nps) in the absence of EDAS. The EDAS/(TiO(2)-Au)(nps) nanocomposite materials provided beneficial role in the environmental remediation and purification process through synergistic photocatalytic activity by an advanced oxidation-reduction processes.
1233544,Nickens et al. 2012,Acquisition of mitochondrial dysregulation and resistance to mitochondrial-mediated apoptosis after genotoxic insult in normal human fibroblasts: a possible model for early stage carcinogenesis,"Acquisition of death-resistance is critical in the evolution of neoplasia. Our aim was to model the early stages of carcinogenesis by examining intracellular alterations in cells that have acquired apoptosis-resistance after exposure to a complex genotoxin. We previously generated sub-populations of BJ-hTERT human diploid fibroblasts, which have acquired death-resistance following exposure to hexavalent chromium [Cr(VI)], a broad-spectrum genotoxicant. Long-term exposure to certain forms of Cr(VI) is associated with respiratory carcinogenesis. Here, we report on the death-sensitivity of subclonal populations derived from clonogenic survivors of BJ-hTERT cells treated with 5 ?M Cr(VI) (DR1, DR2), or selected by dilution-based cloning without treatment (CC1). Following Cr(VI) treatment, CC1 cells downregulated expression of the anti-apoptotic protein Bcl-2 and exhibited extensive expression of cleaved caspase 3. In contrast, the DR cells exhibited no cleaved caspase 3 expression and maintained expression of Bcl-2 following recovery from 24 h Cr(VI) exposure. The DR cells also exhibited attenuated mitochondrial-membrane depolarization and mitochondrial retention of cytochrome c and SMAC/DIABLO following Cr(VI) exposure. The DR cells exhibited less basal mtDNA damage, as compared to CC1 cells, which correlates with intrinsic (non-induced) death-resistance. Notably, there was no difference in p53 protein expression before or after treatment among all cell lines. Taken together, our data suggest the presence of more resilient mitochondria in death-resistant cells, and that death-resistance can be acquired in normal human cells early after genotoxin exposure. We postulate that resistance to mitochondrial-mediated cell death and mitochondrial dysregulation may be an initial phenotypic alteration observed in early stage carcinogenesis.","Acquisition of mitochondrial dysregulation and resistance to mitochondrial-mediated apoptosis after genotoxic insult in normal human fibroblasts: a possible model for early stage carcinogenesis Abs: Acquisition of death-resistance is critical in the evolution of neoplasia. Our aim was to model the early stages of carcinogenesis by examining intracellular alterations in cells that have acquired apoptosis-resistance after exposure to a complex genotoxin. We previously generated sub-populations of BJ-hTERT human diploid fibroblasts, which have acquired death-resistance following exposure to hexavalent chromium [Cr(VI)], a broad-spectrum genotoxicant. Long-term exposure to certain forms of Cr(VI) is associated with respiratory carcinogenesis. Here, we report on the death-sensitivity of subclonal populations derived from clonogenic survivors of BJ-hTERT cells treated with 5 ?M Cr(VI) (DR1, DR2), or selected by dilution-based cloning without treatment (CC1). Following Cr(VI) treatment, CC1 cells downregulated expression of the anti-apoptotic protein Bcl-2 and exhibited extensive expression of cleaved caspase 3. In contrast, the DR cells exhibited no cleaved caspase 3 expression and maintained expression of Bcl-2 following recovery from 24 h Cr(VI) exposure. The DR cells also exhibited attenuated mitochondrial-membrane depolarization and mitochondrial retention of cytochrome c and SMAC/DIABLO following Cr(VI) exposure. The DR cells exhibited less basal mtDNA damage, as compared to CC1 cells, which correlates with intrinsic (non-induced) death-resistance. Notably, there was no difference in p53 protein expression before or after treatment among all cell lines. Taken together, our data suggest the presence of more resilient mitochondria in death-resistant cells, and that death-resistance can be acquired in normal human cells early after genotoxin exposure. We postulate that resistance to mitochondrial-mediated cell death and mitochondrial dysregulation may be an initial phenotypic alteration observed in early stage carcinogenesis."
1233543,Scarselli et al. 2012,Hexavalent chromium compounds in the workplace: assessing the extent and magnitude of occupational exposure in Italy,"Hexavalent chromium (Cr(VI)) compounds have been classified as carcinogenic to humans. This study evaluates the extent and magnitude of occupational exposures to Cr(VI) in Italy. Data were collected from exposure registries of companies compulsorily notified by the National Workers' Compensation Authority. Each measurement was characterized by economic activity sector, work force size, worker personal data, job description, year of measurement, and level of exposure. Descriptive statistical analysis was carried out on the retrieved information. The number of workers potentially exposed was estimated for some industrial sectors. A mixed-effects model was adopted to evaluate the association between exposure variables and exposure concentrations. Over 8400 measurements of Cr(VI) exposures were selected from the database of registries for 1996-2009. Most exposures occurred in the manufacture of fabricated metal products (&gt;50%), and the occupational group most frequently measured was metal finishing-, plating- and coating-machine operators (&gt;52%). Measurements were associated with various Cr(VI) compounds, including chromium trioxide, potassium dichromate, sodium dichromate, strontium chromate, and zinc chromate. Cr(VI) exposure has decreased in more recent years, and the fixed-effects (Cr(VI) compound, activity sector, size and location of the facility, job category, and year of measurement of the final statistical model explained more than 70% of the variance in the observed exposure data. This study summarized data recorded in the Italian occupational exposure database and identified specific exposure patterns to Cr(VI). The mean level of exposure to Cr(VI) was 30.41 ?g/m(3), and 50,118 workers were estimated at exposure risk in the selected industrial sectors. Systematic recording of occupational exposures is a source of data that allows recognition of high risk situations and improvements in exposure assessment for epidemiologic studies.","Hexavalent chromium compounds in the workplace: assessing the extent and magnitude of occupational exposure in Italy Abs: Hexavalent chromium (Cr(VI)) compounds have been classified as carcinogenic to humans. This study evaluates the extent and magnitude of occupational exposures to Cr(VI) in Italy. Data were collected from exposure registries of companies compulsorily notified by the National Workers' Compensation Authority. Each measurement was characterized by economic activity sector, work force size, worker personal data, job description, year of measurement, and level of exposure. Descriptive statistical analysis was carried out on the retrieved information. The number of workers potentially exposed was estimated for some industrial sectors. A mixed-effects model was adopted to evaluate the association between exposure variables and exposure concentrations. Over 8400 measurements of Cr(VI) exposures were selected from the database of registries for 1996-2009. Most exposures occurred in the manufacture of fabricated metal products (&gt;50%), and the occupational group most frequently measured was metal finishing-, plating- and coating-machine operators (&gt;52%). Measurements were associated with various Cr(VI) compounds, including chromium trioxide, potassium dichromate, sodium dichromate, strontium chromate, and zinc chromate. Cr(VI) exposure has decreased in more recent years, and the fixed-effects (Cr(VI) compound, activity sector, size and location of the facility, job category, and year of measurement of the final statistical model explained more than 70% of the variance in the observed exposure data. This study summarized data recorded in the Italian occupational exposure database and identified specific exposure patterns to Cr(VI). The mean level of exposure to Cr(VI) was 30.41 ?g/m(3), and 50,118 workers were estimated at exposure risk in the selected industrial sectors. Systematic recording of occupational exposures is a source of data that allows recognition of high risk situations and improvements in exposure assessment for epidemiologic studies."
1233542,Sahinkaya et al. 2012,Hexavalent chromium reduction in a sulfur reducing packed-bed bioreactor,"The most commonly used approach for the detoxification of hazardous industrial effluents and wastewaters containing Cr(VI) is its reduction to the much less toxic and immobile form of Cr(III). This study investigates the cleanup of Cr(VI) containing wastewaters using elemental sulfur as electron acceptor, for the production of hydrogen sulfide that induces Cr(VI) reduction. An elemental sulfur reducing packed-bed bioreactor was operated at 28-30°C for more than 250 days under varying influent Cr(VI) concentrations (5.0-50.0 mg/L) and hydraulic retention times (HRTs, 0.36-1.0 day). Ethanol or acetate (1000 mg/L COD) was used as carbon source and electron donor. The degree of COD oxidation varied between 30% and 85%, depending on the operating conditions and the type of organic carbon source. The oxidation of organic matter was coupled with the production of hydrogen sulfide, which reached a maximum concentration of 750 mg/L. The biologically produced hydrogen sulfide reduced Cr(VI) chemically to Cr(III) that precipitated in the reactor. Reduction of Cr(VI) and removal efficiency of total chromium always exceeded 97% and 85%, respectively, implying that the reduced chromium was retained in the bioreactor. This study showed that sulfur can be used as an electron acceptor to produce hydrogen sulfide that induces efficient reduction and immobilization of Cr(VI), thus enabling decontamination of Cr(VI) polluted wastewaters.","Hexavalent chromium reduction in a sulfur reducing packed-bed bioreactor Abs: The most commonly used approach for the detoxification of hazardous industrial effluents and wastewaters containing Cr(VI) is its reduction to the much less toxic and immobile form of Cr(III). This study investigates the cleanup of Cr(VI) containing wastewaters using elemental sulfur as electron acceptor, for the production of hydrogen sulfide that induces Cr(VI) reduction. An elemental sulfur reducing packed-bed bioreactor was operated at 28-30°C for more than 250 days under varying influent Cr(VI) concentrations (5.0-50.0 mg/L) and hydraulic retention times (HRTs, 0.36-1.0 day). Ethanol or acetate (1000 mg/L COD) was used as carbon source and electron donor. The degree of COD oxidation varied between 30% and 85%, depending on the operating conditions and the type of organic carbon source. The oxidation of organic matter was coupled with the production of hydrogen sulfide, which reached a maximum concentration of 750 mg/L. The biologically produced hydrogen sulfide reduced Cr(VI) chemically to Cr(III) that precipitated in the reactor. Reduction of Cr(VI) and removal efficiency of total chromium always exceeded 97% and 85%, respectively, implying that the reduced chromium was retained in the bioreactor. This study showed that sulfur can be used as an electron acceptor to produce hydrogen sulfide that induces efficient reduction and immobilization of Cr(VI), thus enabling decontamination of Cr(VI) polluted wastewaters."
1233541,Wu et al. 2012,Mechanism of the reduction of hexavalent chromium by organo-montmorillonite supported iron nanoparticles,"Iron nanoparticles exhibit greater reactivity than micro-sized Fe(0), and they impart advantages for groundwater remediation. In this paper, supported iron nanoparticles were synthesized to further enhance the speed and efficiency of remediation. Natural montmorillonite and organo-montmorillonite were chosen as supporting materials. The capacity of supported iron nanoparticles was evaluated, compared to unsupported iron nanoparticles, for the reduction of aqueous Cr(VI). The reduction of Cr(VI) was much greater with organo-montmorillonite supported iron nanoparticles and fitted the pseudo-second order equation better. With a dose at 0.47 g/L, a total removal capacity of 106 mg Cr/g Fe(0) was obtained. Other factors that affect the efficiency of Cr(VI) removal, such as pH values, the initial Cr(VI) concentration and storage time of nanoparticles were investigated. X-ray photoelectron spectrometry (XPS) and X-ray absorption near edge structure (XANES) were used to figure out the mechanism of the removal of Cr(VI). XPS indicated that the Cr(VI) bound to the particle surface was completely reduced to Cr(III) under a range of conditions. XANES confirmed that the Cr(VI) reacted with iron nanoparticles was completely reduced to Cr(III).","Mechanism of the reduction of hexavalent chromium by organo-montmorillonite supported iron nanoparticles Abs: Iron nanoparticles exhibit greater reactivity than micro-sized Fe(0), and they impart advantages for groundwater remediation. In this paper, supported iron nanoparticles were synthesized to further enhance the speed and efficiency of remediation. Natural montmorillonite and organo-montmorillonite were chosen as supporting materials. The capacity of supported iron nanoparticles was evaluated, compared to unsupported iron nanoparticles, for the reduction of aqueous Cr(VI). The reduction of Cr(VI) was much greater with organo-montmorillonite supported iron nanoparticles and fitted the pseudo-second order equation better. With a dose at 0.47 g/L, a total removal capacity of 106 mg Cr/g Fe(0) was obtained. Other factors that affect the efficiency of Cr(VI) removal, such as pH values, the initial Cr(VI) concentration and storage time of nanoparticles were investigated. X-ray photoelectron spectrometry (XPS) and X-ray absorption near edge structure (XANES) were used to figure out the mechanism of the removal of Cr(VI). XPS indicated that the Cr(VI) bound to the particle surface was completely reduced to Cr(III) under a range of conditions. XANES confirmed that the Cr(VI) reacted with iron nanoparticles was completely reduced to Cr(III)."
1233540,Basu and  Johnson 2012,Determination of hexavalent chromium reduction using cr stable isotopes: isotopic fractionation factors for permeable reactive barrier materials,"Cr stable isotope measurements can provide improved estimates of the extent of Cr(VI) reduction to less toxic Cr(III). The relationship between observed (53)Cr/(52)Cr ratio shifts and the extent of reduction can be calibrated by determining the isotopic fractionation factor for relevant reactions. Permeable reactive barriers (PRB) made of Fe(0) and in situ redox manipulation (ISRM) zones effectively remediate Cr-contaminated aquifers. Here, we determine the isotopic fractionations for dominant reductants in reactive barriers and reduced sediments obtained from an ISRM zone at the US DOE's Hanford site. In all cases, significant isotopic fractionation was observed; fractionation (expressed as ?) was -3.91‰ for Fe(II)-doped goethite, -2.11‰ for FeS, -2.65‰ for green rust, -2.67‰ for FeCO(3), and -3.18‰ for ISRM zone sediments. These results provide a better calibration of the relationship between Cr isotope ratios and the extent of Cr(VI) reduction and aid in interpretation of Cr isotope data from systems with reactive barriers.","Determination of hexavalent chromium reduction using cr stable isotopes: isotopic fractionation factors for permeable reactive barrier materials Abs: Cr stable isotope measurements can provide improved estimates of the extent of Cr(VI) reduction to less toxic Cr(III). The relationship between observed (53)Cr/(52)Cr ratio shifts and the extent of reduction can be calibrated by determining the isotopic fractionation factor for relevant reactions. Permeable reactive barriers (PRB) made of Fe(0) and in situ redox manipulation (ISRM) zones effectively remediate Cr-contaminated aquifers. Here, we determine the isotopic fractionations for dominant reductants in reactive barriers and reduced sediments obtained from an ISRM zone at the US DOE's Hanford site. In all cases, significant isotopic fractionation was observed; fractionation (expressed as ?) was -3.91‰ for Fe(II)-doped goethite, -2.11‰ for FeS, -2.65‰ for green rust, -2.67‰ for FeCO(3), and -3.18‰ for ISRM zone sediments. These results provide a better calibration of the relationship between Cr isotope ratios and the extent of Cr(VI) reduction and aid in interpretation of Cr isotope data from systems with reactive barriers."
1233539,Arzate-Cárdenas and  Martínez-Jerónimo 2012,Energy reserve modification in different age groups of Daphnia schoedleri (Anomopoda: Daphniidae) exposed to hexavalent chromium,"Caloric content is a reliable biomaker of effect since it is modified by exposure to toxicants that can alter basal metabolism. Since organisms' age modifies how energy resources are allocated and modifies the activity of antioxidant enzymes, the response to toxic agents could be altered with age. Seven age groups of Daphnia schoedleri (0, 3, 5, 7, 14, 21, and 28-day-old) were exposed for 24h to two sublethal concentrations of Cr(VI): 1/25 and 1/5 of the 48 h EC(50) of each age group, to determine the age at which susceptibility to Cr(VI) is highest. To evaluate energy content, carbohydrate, protein and lipid reserves were quantified and antioxidant enzymes activity was assessed (SOD, CAT, GPx, and GR). Furthermore, an integrative approach was applied to evaluate both sets of responses and interpret them as a whole in a simply visual way, achieved by the integrated biomarker response approach. Results indicate that Cr(VI) induced significant differences in all age groups. Seven and 14-day-old organisms were exposed to the highest concentrations (based on their EC50) and showed greater tolerance to this metal. Susceptibility to the toxicant was highest in younger specimens in which energy requirements are greater due to high growth rates (basal metabolism), as a result of which more energy reserves are expended to satisfy demands in terms of growth and response to toxicants.","Energy reserve modification in different age groups of Daphnia schoedleri (Anomopoda: Daphniidae) exposed to hexavalent chromium Abs: Caloric content is a reliable biomaker of effect since it is modified by exposure to toxicants that can alter basal metabolism. Since organisms' age modifies how energy resources are allocated and modifies the activity of antioxidant enzymes, the response to toxic agents could be altered with age. Seven age groups of Daphnia schoedleri (0, 3, 5, 7, 14, 21, and 28-day-old) were exposed for 24h to two sublethal concentrations of Cr(VI): 1/25 and 1/5 of the 48 h EC(50) of each age group, to determine the age at which susceptibility to Cr(VI) is highest. To evaluate energy content, carbohydrate, protein and lipid reserves were quantified and antioxidant enzymes activity was assessed (SOD, CAT, GPx, and GR). Furthermore, an integrative approach was applied to evaluate both sets of responses and interpret them as a whole in a simply visual way, achieved by the integrated biomarker response approach. Results indicate that Cr(VI) induced significant differences in all age groups. Seven and 14-day-old organisms were exposed to the highest concentrations (based on their EC50) and showed greater tolerance to this metal. Susceptibility to the toxicant was highest in younger specimens in which energy requirements are greater due to high growth rates (basal metabolism), as a result of which more energy reserves are expended to satisfy demands in terms of growth and response to toxicants."
1233537,Djouider 2012,Radiolytic formation of non-toxic Cr(III) from toxic Cr(VI) in formate containing aqueous solutions: A system for water treatment,"Toxic hexavalent chromium Cr(VI) in the form of potassium dichromate was radiolytically reduced to non-toxic trivalent chromium Cr(III) in N(2)O-saturated aqueous solutions containing formate. This reduction by the electron donor (CO(2)H/CO(2)(-)) produced by continuous radiolysis of water, was a linear function of the absorbed dose. This reaction was pH and dose rate dependent. pH was an important parameter in the reduction, as it affects both chemical speciation of Cr(VI) and formate. Possible mechanisms related to dose rate dependence of removal of Cr(VI) are presented. At pH 3 a decrease in the radiation induced reduction of Cr(VI) was observed with increasing hydrogen peroxide concentration. A mechanism to account for this variation is proposed. These findings suggest that irradiation of Cr(VI) solutions in presence of formate can be effective, economical and simple means for treatment of waste water contaminated with hexavalent Cr(VI).","Radiolytic formation of non-toxic Cr(III) from toxic Cr(VI) in formate containing aqueous solutions: A system for water treatment Abs: Toxic hexavalent chromium Cr(VI) in the form of potassium dichromate was radiolytically reduced to non-toxic trivalent chromium Cr(III) in N(2)O-saturated aqueous solutions containing formate. This reduction by the electron donor (CO(2)H/CO(2)(-)) produced by continuous radiolysis of water, was a linear function of the absorbed dose. This reaction was pH and dose rate dependent. pH was an important parameter in the reduction, as it affects both chemical speciation of Cr(VI) and formate. Possible mechanisms related to dose rate dependence of removal of Cr(VI) are presented. At pH 3 a decrease in the radiation induced reduction of Cr(VI) was observed with increasing hydrogen peroxide concentration. A mechanism to account for this variation is proposed. These findings suggest that irradiation of Cr(VI) solutions in presence of formate can be effective, economical and simple means for treatment of waste water contaminated with hexavalent Cr(VI)."
1233536,Guha et al. 2011,Antioxidant activity of Lawsonia inermis extracts inhibits Chromium(VI)-induced cellular and DNA toxicity,"Hexavalent chromium Cr(VI) is a very strong oxidant which consequently causes high cytotoxicity through oxidative stress. Prevention of Cr(VI)-induced cellular damage has been sought in this study in aqueous and methanolic extracts of Lawsonia inermis Linn. (Lythraceae), commonly known as Henna. The extracts showed significant (P < .05) potential in scavenging free radicals (DPPH(•) and ABTS(•+)) and Fe(3+), and in inhibiting lipid peroxidation. DNA damage caused by exposure of pBR322 to Cr(VI)-UV is markedly inhibited by both extracts in varying degrees. A distinct decline in Cr(VI)-induced cytotoxicity was noticed in MDA-MB-435S (human breast carcinoma) cells with an increase in dosage of both extracts individually. Furthermore, both extracts proved to contain a high content of phenolic compounds which were found to have a strong and significant (P < .05) positive correlation to the radical scavenging potential, lipid peroxidation inhibition capacity and cyto-protective efficiency against Cr(VI)-induced oxidative cellular damage. HPLC analysis identified some of the major phenolic compounds in both extracts, which might be responsible for the antioxidant potential and the properties of DNA and cyto-protection. This study contributes to the search for natural resources that might yield potent therapeutic drugs against Cr(VI)-induced oxidative cell damage.","Antioxidant activity of Lawsonia inermis extracts inhibits Chromium(VI)-induced cellular and DNA toxicity Abs: Hexavalent chromium Cr(VI) is a very strong oxidant which consequently causes high cytotoxicity through oxidative stress. Prevention of Cr(VI)-induced cellular damage has been sought in this study in aqueous and methanolic extracts of Lawsonia inermis Linn. (Lythraceae), commonly known as Henna. The extracts showed significant (P < .05) potential in scavenging free radicals (DPPH(•) and ABTS(•+)) and Fe(3+), and in inhibiting lipid peroxidation. DNA damage caused by exposure of pBR322 to Cr(VI)-UV is markedly inhibited by both extracts in varying degrees. A distinct decline in Cr(VI)-induced cytotoxicity was noticed in MDA-MB-435S (human breast carcinoma) cells with an increase in dosage of both extracts individually. Furthermore, both extracts proved to contain a high content of phenolic compounds which were found to have a strong and significant (P < .05) positive correlation to the radical scavenging potential, lipid peroxidation inhibition capacity and cyto-protective efficiency against Cr(VI)-induced oxidative cellular damage. HPLC analysis identified some of the major phenolic compounds in both extracts, which might be responsible for the antioxidant potential and the properties of DNA and cyto-protection. This study contributes to the search for natural resources that might yield potent therapeutic drugs against Cr(VI)-induced oxidative cell damage."
1233535,Batool et al. 2012,Hexavalent chromium reduction by bacteria from tannery effluent,"Chromium is generated from several industrial processes. It occurs in different oxidation states, but Cr(III) and Cr(VI) are the most common ones. Cr(VI) is a toxic, soluble environmental contaminant. Some bacteria are able to reduce hexavalent chromium to the insoluble and less toxic Cr(III), and thus chromate bioremediation is of considerable interest. An indigenous chromium-reducing bacterial strain, Rb-2, isolated from a tannery water sample, was identified as Ochrobactrum intermedium, on the basis of 16S rRNA gene sequencing. The influence of factors like temperature of incubation, initial concentration of Cr, mobility of bacteria, and different carbon sources were studied to test the ability of the bacterium to reduce Cr(VI) under variable environmental conditions. The ability of the bacterial strain to reduce hexavalent chromium in artificial and industrial sewage water was evaluated. It was observed that the mechanism of resistance to metal was not due to the change in the permeability barrier of the cell membrane, and the enzyme activity was found to be inductive. Intracellular reduction of Cr(VI) was proven by reductase assay using cell-free extract. Scanning electron microscopy revealed chromium precipitates on bacterial cell surfaces, and transmission electron microscopy showed the outer as well as inner distribution of Cr(VI). This bacterial strain can be useful for Cr(VI) detoxification under a wide range of environmental conditions.","Hexavalent chromium reduction by bacteria from tannery effluent Abs: Chromium is generated from several industrial processes. It occurs in different oxidation states, but Cr(III) and Cr(VI) are the most common ones. Cr(VI) is a toxic, soluble environmental contaminant. Some bacteria are able to reduce hexavalent chromium to the insoluble and less toxic Cr(III), and thus chromate bioremediation is of considerable interest. An indigenous chromium-reducing bacterial strain, Rb-2, isolated from a tannery water sample, was identified as Ochrobactrum intermedium, on the basis of 16S rRNA gene sequencing. The influence of factors like temperature of incubation, initial concentration of Cr, mobility of bacteria, and different carbon sources were studied to test the ability of the bacterium to reduce Cr(VI) under variable environmental conditions. The ability of the bacterial strain to reduce hexavalent chromium in artificial and industrial sewage water was evaluated. It was observed that the mechanism of resistance to metal was not due to the change in the permeability barrier of the cell membrane, and the enzyme activity was found to be inductive. Intracellular reduction of Cr(VI) was proven by reductase assay using cell-free extract. Scanning electron microscopy revealed chromium precipitates on bacterial cell surfaces, and transmission electron microscopy showed the outer as well as inner distribution of Cr(VI). This bacterial strain can be useful for Cr(VI) detoxification under a wide range of environmental conditions."
1233534,Myers 2012,The effects of chromium(VI) on the thioredoxin system: Implications for redox regulation,"Hexavalent chromium [Cr(VI)] compounds are highly redox active and have long been recognized as potent cytotoxins and carcinogens. The intracellular reduction of Cr(VI) generates reactive Cr intermediates, which are themselves strong oxidants, as well as superoxide, hydrogen peroxide, and hydroxyl radical. These probably contribute to the oxidative damage and effects on redox-sensitive transcription factors that have been reported. However, the identification of events that initiate these signaling changes has been elusive. More recent studies show that Cr(VI) causes irreversible inhibition of thioredoxin reductase (TrxR) and oxidation of thioredoxin (Trx) and peroxiredoxin (Prx). Mitochondrial Trx2/Prx3 are more sensitive to Cr(VI) treatment than cytosolic Trx1/Prx1, although both compartments show thiol oxidation with higher doses or longer treatments. Thiol redox proteomics demonstrate that Trx2, Prx3, and Trx1 are among the most sensitive proteins in cells to Cr(VI) treatment. Their oxidation could therefore represent initiating events that have widespread implications for protein thiol redox control and for multiple aspects of redox signaling. This review summarizes the effects of Cr(VI) on the TrxR/Trx system and how these events could influence a number of downstream redox signaling systems that are influenced by Cr(VI) exposure. Some of the signaling events discussed include the activation of apoptosis signal regulating kinase and MAP kinases (p38 and JNK) and the modulation of a number of redox-sensitive transcription factors including AP-1, NF-?B, p53, and Nrf2.","The effects of chromium(VI) on the thioredoxin system: Implications for redox regulation Abs: Hexavalent chromium [Cr(VI)] compounds are highly redox active and have long been recognized as potent cytotoxins and carcinogens. The intracellular reduction of Cr(VI) generates reactive Cr intermediates, which are themselves strong oxidants, as well as superoxide, hydrogen peroxide, and hydroxyl radical. These probably contribute to the oxidative damage and effects on redox-sensitive transcription factors that have been reported. However, the identification of events that initiate these signaling changes has been elusive. More recent studies show that Cr(VI) causes irreversible inhibition of thioredoxin reductase (TrxR) and oxidation of thioredoxin (Trx) and peroxiredoxin (Prx). Mitochondrial Trx2/Prx3 are more sensitive to Cr(VI) treatment than cytosolic Trx1/Prx1, although both compartments show thiol oxidation with higher doses or longer treatments. Thiol redox proteomics demonstrate that Trx2, Prx3, and Trx1 are among the most sensitive proteins in cells to Cr(VI) treatment. Their oxidation could therefore represent initiating events that have widespread implications for protein thiol redox control and for multiple aspects of redox signaling. This review summarizes the effects of Cr(VI) on the TrxR/Trx system and how these events could influence a number of downstream redox signaling systems that are influenced by Cr(VI) exposure. Some of the signaling events discussed include the activation of apoptosis signal regulating kinase and MAP kinases (p38 and JNK) and the modulation of a number of redox-sensitive transcription factors including AP-1, NF-?B, p53, and Nrf2."
1233533,Gurung et al. 2012,Semi-continuous detection of toxic hexavalent chromium using a sulfur-oxidizing bacteria biosensor,"Toxicity testing is becoming a useful tool for environmental risk assessment. A biosensor based on the metabolic properties of sulfur-oxidizing bacteria (SOB) has been applied for the detection of toxic chemicals in water. The methodology exploits the ability of SOB to oxidize elemental sulfur to sulfuric acid under aerobic conditions. The reaction results in an increase in electrical conductivity (EC) and a decrease in pH. Five hours after Cr(6+) was added to the SOB biosensor operated in semi-continuous mode (1 min rapid feeding and 29 min batch reaction), a decrease in effluent EC and an increase in pH (from 2-3 to 6) were detected due to Cr(6+) toxicity to SOB. The SOB biosensor is simple; it can detect toxic levels of Cr(6+) on the order of minutes to hours, a useful time scale for early warning detection systems designed to protect the environment from further degradation.","Semi-continuous detection of toxic hexavalent chromium using a sulfur-oxidizing bacteria biosensor Abs: Toxicity testing is becoming a useful tool for environmental risk assessment. A biosensor based on the metabolic properties of sulfur-oxidizing bacteria (SOB) has been applied for the detection of toxic chemicals in water. The methodology exploits the ability of SOB to oxidize elemental sulfur to sulfuric acid under aerobic conditions. The reaction results in an increase in electrical conductivity (EC) and a decrease in pH. Five hours after Cr(6+) was added to the SOB biosensor operated in semi-continuous mode (1 min rapid feeding and 29 min batch reaction), a decrease in effluent EC and an increase in pH (from 2-3 to 6) were detected due to Cr(6+) toxicity to SOB. The SOB biosensor is simple; it can detect toxic levels of Cr(6+) on the order of minutes to hours, a useful time scale for early warning detection systems designed to protect the environment from further degradation."
1233532,Singh et al. 2012,Removal of hexavalent chromium from contaminated ground water using zero-valent iron nanoparticles,"Batch experiments were conducted on ground water samples collected from a site contaminated with Cr(VI) to evaluate the redox potential of zero-valent iron (Fe(0)) nanoparticles for remediation of Cr(VI)-contaminated ground water. For this, various samples of contaminated ground water were allowed to react with various loadings of Fe(0) nanoparticles for a reaction period of 60 min. Data showed 100% reduction of Cr(VI) in all the contaminated ground water samples after treatment with 0.20 gL(-1) of Fe(0) nanoparticles. An increase in the reduction of Cr(VI) from 45% to 100% was noticed with the increase in the loading of Fe(0) nanoparticles from 0.05 to 0.20 gL(-1). Reaction kinetics of Cr(VI) reduction showed pseudo first-order kinetics with rate constant in the range of 1.1?×?10(-3) to 3.9?×?10(-3) min(-1). This work demonstrates the potential utility of Fe(0) nanoparticles in treatment and remediation of Cr(VI)-contaminated water source.","Removal of hexavalent chromium from contaminated ground water using zero-valent iron nanoparticles Abs: Batch experiments were conducted on ground water samples collected from a site contaminated with Cr(VI) to evaluate the redox potential of zero-valent iron (Fe(0)) nanoparticles for remediation of Cr(VI)-contaminated ground water. For this, various samples of contaminated ground water were allowed to react with various loadings of Fe(0) nanoparticles for a reaction period of 60 min. Data showed 100% reduction of Cr(VI) in all the contaminated ground water samples after treatment with 0.20 gL(-1) of Fe(0) nanoparticles. An increase in the reduction of Cr(VI) from 45% to 100% was noticed with the increase in the loading of Fe(0) nanoparticles from 0.05 to 0.20 gL(-1). Reaction kinetics of Cr(VI) reduction showed pseudo first-order kinetics with rate constant in the range of 1.1?×?10(-3) to 3.9?×?10(-3) min(-1). This work demonstrates the potential utility of Fe(0) nanoparticles in treatment and remediation of Cr(VI)-contaminated water source."
1233531,Kopec et al. 2012,Comparative toxicogenomic analysis of oral Cr(VI) exposure effects in rat and mouse small intestinal epithelia,"Continuous exposure to high concentrations of hexavalent chromium [Cr(VI)] in drinking water results in intestinal tumors in mice but not rats. Concentration-dependent gene expression effects were evaluated in female F344 rat duodenal and jejunal epithelia following 7 and 90days of exposure to 0.3-520mg/L (as sodium dichromate dihydrate, SDD) in drinking water. Whole-genome microarrays identified 3269 and 1815 duodenal, and 4557 and 1534 jejunal differentially expressed genes at 8 and 91days, respectively, with significant overlaps between the intestinal segments. Functional annotation identified gene expression changes associated with oxidative stress, cell cycle, cell death, and immune response that were consistent with reported changes in redox status and histopathology. Comparative analysis with B6C3F1 mouse data from a similarly designed study identified 2790 differentially expressed rat orthologs in the duodenum compared to 5013 mouse orthologs at day 8, and only 1504 rat and 3484 mouse orthologs at day 91. Automated dose-response modeling resulted in similar median EC(50)s in the rodent duodenal and jejunal mucosae. Comparative examination of differentially expressed genes also identified divergently regulated orthologs. Comparable numbers of differentially expressed genes were observed at equivalent Cr concentrations (?g Cr/g duodenum). However, mice accumulated higher Cr levels than rats at ?170mg/L SDD, resulting in a ~2-fold increase in the number of differentially expressed genes. These qualitative and quantitative differences in differential gene expression, which correlate with differences in tissue dose, likely contribute to the disparate intestinal tumor outcomes.","Comparative toxicogenomic analysis of oral Cr(VI) exposure effects in rat and mouse small intestinal epithelia Abs: Continuous exposure to high concentrations of hexavalent chromium [Cr(VI)] in drinking water results in intestinal tumors in mice but not rats. Concentration-dependent gene expression effects were evaluated in female F344 rat duodenal and jejunal epithelia following 7 and 90days of exposure to 0.3-520mg/L (as sodium dichromate dihydrate, SDD) in drinking water. Whole-genome microarrays identified 3269 and 1815 duodenal, and 4557 and 1534 jejunal differentially expressed genes at 8 and 91days, respectively, with significant overlaps between the intestinal segments. Functional annotation identified gene expression changes associated with oxidative stress, cell cycle, cell death, and immune response that were consistent with reported changes in redox status and histopathology. Comparative analysis with B6C3F1 mouse data from a similarly designed study identified 2790 differentially expressed rat orthologs in the duodenum compared to 5013 mouse orthologs at day 8, and only 1504 rat and 3484 mouse orthologs at day 91. Automated dose-response modeling resulted in similar median EC(50)s in the rodent duodenal and jejunal mucosae. Comparative examination of differentially expressed genes also identified divergently regulated orthologs. Comparable numbers of differentially expressed genes were observed at equivalent Cr concentrations (?g Cr/g duodenum). However, mice accumulated higher Cr levels than rats at ?170mg/L SDD, resulting in a ~2-fold increase in the number of differentially expressed genes. These qualitative and quantitative differences in differential gene expression, which correlate with differences in tissue dose, likely contribute to the disparate intestinal tumor outcomes."
1233530,Mishra and  Mohanty 2012,"Effect of sublethal hexavalent chromium exposure on the pituitary-ovarian axis of a teleost, Channa punctatus (Bloch)","Exposure to sublethal hexavalent chromium (as 2 and 4 mg L(-1) potassium dichromate for 1 and 2 months) during late preparatory to mid prespawning phase of annual reproductive cycle severely affected the pituitary-ovarian axis of a teleost Channa punctatus. Gonadosomatic index (GSI), ovarian histopathology, immunocytochemistry of the pituitary gonadotrophs (LH?-immunoreactive cells), and serum 17?-estradiol level revealed distinct dose and duration-dependent effects. Gonadosomatic index was declined. Diameter of ovary as well as ovarian follicles was reduced along with a distinct variation in the percentage of follicles. The greater percentage of previtellogenic follicles (stage I) and decline in vitellogenic ones (stage II and stage III) compared to control indicated the arrest of follicular development. The percentage of atretic follicles was also increased indicating toxic impact of metal on ovary. Decreased serum level of ovarian steroid 17?-estradiol further indicated the same. Chromium interference of the pituitary was demonstrated as atrophy and less immunointensity of LH-immunoreactive gonadotrophs. Thus, the hexavalent chromium impaired the pituitary-ovarian axis affecting at the sites of both pituitary and ovary. © 2010 Wiley Periodicals, Inc. Environ Toxicol, 2012.","Effect of sublethal hexavalent chromium exposure on the pituitary-ovarian axis of a teleost, Channa punctatus (Bloch) Abs: Exposure to sublethal hexavalent chromium (as 2 and 4 mg L(-1) potassium dichromate for 1 and 2 months) during late preparatory to mid prespawning phase of annual reproductive cycle severely affected the pituitary-ovarian axis of a teleost Channa punctatus. Gonadosomatic index (GSI), ovarian histopathology, immunocytochemistry of the pituitary gonadotrophs (LH?-immunoreactive cells), and serum 17?-estradiol level revealed distinct dose and duration-dependent effects. Gonadosomatic index was declined. Diameter of ovary as well as ovarian follicles was reduced along with a distinct variation in the percentage of follicles. The greater percentage of previtellogenic follicles (stage I) and decline in vitellogenic ones (stage II and stage III) compared to control indicated the arrest of follicular development. The percentage of atretic follicles was also increased indicating toxic impact of metal on ovary. Decreased serum level of ovarian steroid 17?-estradiol further indicated the same. Chromium interference of the pituitary was demonstrated as atrophy and less immunointensity of LH-immunoreactive gonadotrophs. Thus, the hexavalent chromium impaired the pituitary-ovarian axis affecting at the sites of both pituitary and ovary. © 2010 Wiley Periodicals, Inc. Environ Toxicol, 2012."
1233529,Medan et al. 2012,Multifunctional Role of Bcl-2 in Malignant Transformation and Tumorigenesis of Cr(VI)-Transformed Lung Cells,"B-cell lymphoma-2 (Bcl-2) is an antiapoptotic protein known to be important in the regulation of apoptosis in various cell types. However, its role in malignant transformation and tumorigenesis of human lung cells is not well understood. We previously reported that chronic exposure of human lung epithelial cells to the carcinogenic hexavalent chromium Cr(VI) caused malignant transformation and Bcl-2 upregulation; however, the role of Bcl-2 in the transformation is unclear. Using a gene silencing approach, we showed that Bcl-2 plays an important role in the malignant properties of Cr(VI)-transformed cells. Downregulation of Bcl-2 inhibited the invasive and proliferative properties of the cells as well as their colony forming and angiogenic activities, which are upregulated in the transformed cells as compared to control cells. Furthermore, animal studies showed the inhibitory effect of Bcl-2 knockdown on the tumorigenesis of Cr(VI)-transformed cells. The role of Bcl-2 in malignant transformation and tumorigenesis was confirmed by gene silencing experiments using human lung carcinoma NCI-H460 cells. These cells exhibited aggressive malignant phenotypes similar to those of Cr(VI)-transformed cells. Knockdown of Bcl-2 in the H460 cells inhibited malignant and tumorigenic properties of the cells, indicating the general role of Bcl-2 in human lung tumorigenesis. Ingenuity Pathways Analysis (IPA) revealed potential effectors of Bcl-2 in tumorigenesis regulation. Additionally, using IPA together with ectopic expression of p53, we show p53 as an upstream regulator of Bcl-2 in Cr(VI)-transformed cells. Together, our results indicate the novel and multifunctional role of Bcl-2 in malignant transformation and tumorigenesis of human lung epithelial cells chronically exposed to Cr(VI).","Multifunctional Role of Bcl-2 in Malignant Transformation and Tumorigenesis of Cr(VI)-Transformed Lung Cells Abs: B-cell lymphoma-2 (Bcl-2) is an antiapoptotic protein known to be important in the regulation of apoptosis in various cell types. However, its role in malignant transformation and tumorigenesis of human lung cells is not well understood. We previously reported that chronic exposure of human lung epithelial cells to the carcinogenic hexavalent chromium Cr(VI) caused malignant transformation and Bcl-2 upregulation; however, the role of Bcl-2 in the transformation is unclear. Using a gene silencing approach, we showed that Bcl-2 plays an important role in the malignant properties of Cr(VI)-transformed cells. Downregulation of Bcl-2 inhibited the invasive and proliferative properties of the cells as well as their colony forming and angiogenic activities, which are upregulated in the transformed cells as compared to control cells. Furthermore, animal studies showed the inhibitory effect of Bcl-2 knockdown on the tumorigenesis of Cr(VI)-transformed cells. The role of Bcl-2 in malignant transformation and tumorigenesis was confirmed by gene silencing experiments using human lung carcinoma NCI-H460 cells. These cells exhibited aggressive malignant phenotypes similar to those of Cr(VI)-transformed cells. Knockdown of Bcl-2 in the H460 cells inhibited malignant and tumorigenic properties of the cells, indicating the general role of Bcl-2 in human lung tumorigenesis. Ingenuity Pathways Analysis (IPA) revealed potential effectors of Bcl-2 in tumorigenesis regulation. Additionally, using IPA together with ectopic expression of p53, we show p53 as an upstream regulator of Bcl-2 in Cr(VI)-transformed cells. Together, our results indicate the novel and multifunctional role of Bcl-2 in malignant transformation and tumorigenesis of human lung epithelial cells chronically exposed to Cr(VI)."
1233528,Ciacci et al. 2012,"Effects of sublethal, environmentally relevant concentrations of hexavalent chromium in the gills of Mytilus galloprovincialis","Hexavalent chromium Cr(VI) is an important contaminant released from both domestic and industrial effluents, and represents the predominant chemical form of the metal in aquatic ecosystems. In the marine bivalve Mytilus galloprovincialis exposure to non-toxic, environmentally relevant concentrations of Cr(VI) was shown to modulate functional parameters and gene expression in both the digestive gland and hemocytes. In this work, the effects of exposure to Cr(VI) (0.1-1-10?gL(-1)animal(-1) for 96h) in mussel gills were investigated. Gill morphology and immunolocalization of GSH-transferase (GST), of components involved in cholinergic (AChE and ChAT), adrenergic (TH) and serotoninergic (5-HT(3) receptor) systems, regulating gill motility, were evaluated. Total glutathione content, activities of GSH-related enzymes (glutathione reductase - GSR, GST), of catalase, and of key glycolytic enzymes (phosphofructokinase - PFK and pyruvate kinase - PK) were determined. Moreover, mRNA expression of selected Mytilus genes (GST-?, metallothionein isoforms MT10 and MT20, HSP70 and 5-HT receptor) was assessed by RT-q-PCR. Cr(VI) exposure induced progressive changes in gill morphology and in immunoreactivity to components involved in neurotransmission that were particularly evident at the highest concentration tested, and associated with large metal accumulation. Cr(VI) increased the activities of GST and GSR, and total glutathione content to a different extent at different metal concentrations, this suggesting Cr(VI) detoxication/reduction at the site of metal entry. Cr(VI) exposure also increased the activity of glycolytic enzymes, indicating modulation of carbohydrate metabolism. Significant changes in transcription of different genes were observed. In particular, the mRNA level for the 5-HTR was increased, whereas both decreases and increases were observed for GST-?, MT10, MT20 and HSP70 mRNAs, showing sex- and concentration-related differences. The results demonstrate that Cr(VI) significantly affected functional and molecular parameters in mussel gills, and indicate that this tissue represents the major target of exposure to environmentally relevant concentrations of the metal.","Effects of sublethal, environmentally relevant concentrations of hexavalent chromium in the gills of Mytilus galloprovincialis Abs: Hexavalent chromium Cr(VI) is an important contaminant released from both domestic and industrial effluents, and represents the predominant chemical form of the metal in aquatic ecosystems. In the marine bivalve Mytilus galloprovincialis exposure to non-toxic, environmentally relevant concentrations of Cr(VI) was shown to modulate functional parameters and gene expression in both the digestive gland and hemocytes. In this work, the effects of exposure to Cr(VI) (0.1-1-10?gL(-1)animal(-1) for 96h) in mussel gills were investigated. Gill morphology and immunolocalization of GSH-transferase (GST), of components involved in cholinergic (AChE and ChAT), adrenergic (TH) and serotoninergic (5-HT(3) receptor) systems, regulating gill motility, were evaluated. Total glutathione content, activities of GSH-related enzymes (glutathione reductase - GSR, GST), of catalase, and of key glycolytic enzymes (phosphofructokinase - PFK and pyruvate kinase - PK) were determined. Moreover, mRNA expression of selected Mytilus genes (GST-?, metallothionein isoforms MT10 and MT20, HSP70 and 5-HT receptor) was assessed by RT-q-PCR. Cr(VI) exposure induced progressive changes in gill morphology and in immunoreactivity to components involved in neurotransmission that were particularly evident at the highest concentration tested, and associated with large metal accumulation. Cr(VI) increased the activities of GST and GSR, and total glutathione content to a different extent at different metal concentrations, this suggesting Cr(VI) detoxication/reduction at the site of metal entry. Cr(VI) exposure also increased the activity of glycolytic enzymes, indicating modulation of carbohydrate metabolism. Significant changes in transcription of different genes were observed. In particular, the mRNA level for the 5-HTR was increased, whereas both decreases and increases were observed for GST-?, MT10, MT20 and HSP70 mRNAs, showing sex- and concentration-related differences. The results demonstrate that Cr(VI) significantly affected functional and molecular parameters in mussel gills, and indicate that this tissue represents the major target of exposure to environmentally relevant concentrations of the metal."
1233512,Gabal et al. 1994,Occupational dermatoses among workers in a porcelain manufacturing factory,"The objectives of the present work are to determine the prevalence and risk factors of occurrence of occupational dermatoses among workers in a porcelain manufacturing factory. The study included 235 workers (132 males and 103 females). After history taking, dermatological examination was performed at the work place. Cases of contact dermatitis (CD) were patch tested using potassium dichromate 0.5%, Cobalt chloride 1% and Nickel sulphate 5% in petrolatum. Results showed that the prevalence of occupational dermatoses (OD) was 26.8% among exposed workers. The highest percentage of OD was found among workers in the decoration department. It represented 30.2% of all cases. CD was the commonest presentation among the studied group, it represented 27% of all cases of OD. Results of patch testing indicated that out of 17 cases of CD 12 cases (70%) were of the irritant variety and 5 cases (30%) were of the allergic type. The prevalence of OD was found to be affected by age, duration of work, type of exposure and daily bathing after work.","Occupational dermatoses among workers in a porcelain manufacturing factory Abs: The objectives of the present work are to determine the prevalence and risk factors of occurrence of occupational dermatoses among workers in a porcelain manufacturing factory. The study included 235 workers (132 males and 103 females). After history taking, dermatological examination was performed at the work place. Cases of contact dermatitis (CD) were patch tested using potassium dichromate 0.5%, Cobalt chloride 1% and Nickel sulphate 5% in petrolatum. Results showed that the prevalence of occupational dermatoses (OD) was 26.8% among exposed workers. The highest percentage of OD was found among workers in the decoration department. It represented 30.2% of all cases. CD was the commonest presentation among the studied group, it represented 27% of all cases of OD. Results of patch testing indicated that out of 17 cases of CD 12 cases (70%) were of the irritant variety and 5 cases (30%) were of the allergic type. The prevalence of OD was found to be affected by age, duration of work, type of exposure and daily bathing after work."
1233273,Adachi et al. 1991,Metal concentrations in lung tissue of subjects suffering from lung cancer,"Concentrations of nine metals (Fe, Ca, Mg, Zn, Cu, Co, Ni, Pb and Cr) concentrations in lung tissues from 224 lung cancer cases were compared with those in other cases to achieve an understanding of their contribution to the development of lung cancer and the varieties after the development of cancer. Comparisons of metal concentrations in each cell type of lung cancer were also performed. All cases were collected from routine autopsies in Tokyo and Saitama, Japan. The copper concentration in tissue from lung cancers was significantly higher than that in other specimens, although calcium, magnesium, zinc and cobalt concentrations in lung cancers were significantly lower than those in other cases. There were no significant differences in the 99% intervals (excluding extremely high values for occupationally exposed cases) for chromium, nickel and lead concentrations between lung cancers and other cases, although these values were lower in lung cancers. However, in comparisons of men only, the chromium concentration, the degree of lung contamination and the severity of pulmonary emphysema in lung cancer cases were significantly higher than those in other specimens. Moreover, percentages of lung cancer in men at each degree of contamination and each severity of emphysema increased with increasing grades. Thus, this finding could be evidence that the exposure to contaminants other than chromium and nickel in the air had affected the development of lung cancer, except for occupationally exposed individuals. Therefore, almost all chromium and nickel in lung tissue might not deposit in carcinogenic forms such as hexavalent chromium or nickel subsulfide.(ABSTRACT TRUNCATED AT 250 WORDS)","Metal concentrations in lung tissue of subjects suffering from lung cancer Abs: Concentrations of nine metals (Fe, Ca, Mg, Zn, Cu, Co, Ni, Pb and Cr) concentrations in lung tissues from 224 lung cancer cases were compared with those in other cases to achieve an understanding of their contribution to the development of lung cancer and the varieties after the development of cancer. Comparisons of metal concentrations in each cell type of lung cancer were also performed. All cases were collected from routine autopsies in Tokyo and Saitama, Japan. The copper concentration in tissue from lung cancers was significantly higher than that in other specimens, although calcium, magnesium, zinc and cobalt concentrations in lung cancers were significantly lower than those in other cases. There were no significant differences in the 99% intervals (excluding extremely high values for occupationally exposed cases) for chromium, nickel and lead concentrations between lung cancers and other cases, although these values were lower in lung cancers. However, in comparisons of men only, the chromium concentration, the degree of lung contamination and the severity of pulmonary emphysema in lung cancer cases were significantly higher than those in other specimens. Moreover, percentages of lung cancer in men at each degree of contamination and each severity of emphysema increased with increasing grades. Thus, this finding could be evidence that the exposure to contaminants other than chromium and nickel in the air had affected the development of lung cancer, except for occupationally exposed individuals. Therefore, almost all chromium and nickel in lung tissue might not deposit in carcinogenic forms such as hexavalent chromium or nickel subsulfide.(ABSTRACT TRUNCATED AT 250 WORDS)"
1233267,Kraus and  Muselinovi? 1991,Pre-employment screening for contact dermatitis among the pupils of a metal industry school,"79 male pupils of a metal industry school were investigated, none of whom had yet been occupationally exposed to metals or to cutting oils. In 1 or 2 years, depending on their grade and age, they would all be employees in the metal industry. Each was patch tested with nickel sulfate 5% pet., cobalt chloride 1% pet., and potassium dichromate 0.5% pet., and 28 had a positive reaction to 1 or more of the metals tested. This finding indicates the necessity not only for pre-employment patch testing in industries where contact dermatitis is likely to occur, but that patch testing should be done even earlier in school children, before they decide to enter certain occupations.","Pre-employment screening for contact dermatitis among the pupils of a metal industry school Abs: 79 male pupils of a metal industry school were investigated, none of whom had yet been occupationally exposed to metals or to cutting oils. In 1 or 2 years, depending on their grade and age, they would all be employees in the metal industry. Each was patch tested with nickel sulfate 5% pet., cobalt chloride 1% pet., and potassium dichromate 0.5% pet., and 28 had a positive reaction to 1 or more of the metals tested. This finding indicates the necessity not only for pre-employment patch testing in industries where contact dermatitis is likely to occur, but that patch testing should be done even earlier in school children, before they decide to enter certain occupations."
1233037,Sertoli et al. 1999,Epidemiological survey of contact dermatitis in Italy (1984-1993) by GIRDCA (Gruppo Italiano Ricerca Dermatiti da Contatto e Ambientali),"<strong>BACKGROUND: </strong>The Gruppo Italiano Ricerca Dermatiti da Contatto e Ambientali (GIRDCA) resolved to obtain the most relevant data regarding contact dermatitis (CD) in Italy by means of a multicenter epidemiological study, involving research units (RU) throughout the country. The survey was performed with the collaboration of Generale Per l'Informatica, Rome (GEPIN) over the periods 1984 to 1988 and 1989 to 1993. The analytical study (of a transverse kind) was aimed at supplying prevalence measures.<br /><br /><strong>MATERIALS AND METHODS: </strong>The number of subjects taking part in the survey was 42,839. All patients underwent patch testing with the GIRDCA standard series and were included in the survey only if the final diagnosis was either CD or eczematous dermatitis caused by contact. The main anamnestic, clinical data, and allergological test results of all patients were codified into a chart, and subsequently transcribed into a data bank. The data were then processed cumulatively and were statistically analysed by a chi-square for trend test.<br /><br /><strong>RESULTS: </strong>The four most frequent diagnoses (which, when considered together, make up 39,496 cases, or about 92% of all cases) proved to be nonoccupational allergic contact dermatitis (ACD), nonoccupational irritant contact dermatitis (ICD), occupational ACD, and occupational ICD. The haptens most frequently causing positive reactions in the total number of cases over the first 5 years were, in order of frequency: nickel sulphate, potassium dichromate, cobalt chloride, fragrance mix, balsam of Peru, and, in the second 5-year period, nickel sulphate, cobalt chloride, potassium dichromate, fragrance mix, and thimerosal. Occupational CD (ACD and ICD) was present in 11,694 cases overall, corresponding to approximately 27% of the total number of cases examined, and approximately 29% of all CD (including forms of nonoccupational CD). Regarding distribution by sex, a substantial equivalence of males and females for ACD, and a prevalence of females with ICD can be observed. Five occupations were reputed to be responsible for over 60% of total cases of occupational CD (housewives, bricklayers, workers in the metallurgic and mechanical industries, hairdressers, and healthcare personnel). Regarding the pathogenesis, a clearly dominant percentage of ACD may be observed among bricklayers and hairdressers, and of ICD among housewives. The haptens most frequently noted over the entire decade as the cause of positive reaction in occupational ACD were, in order of frequency, potassium dichromate, nickel sulphate, cobalt chloride, p-phenylenediamine and thiuram mix. Nonoccupational CD (ACD and ICD) was present in 27,802 cases overall, corresponding to about 65% of all cases under examination and over 70% of all CD (also including forms of occupational CD). In regard to distribution by sex, a clear dominance of females, as opposed to males, can be noted for ACD and also (although to a lesser extent) for ICD. The main products and materials (ie, components and relative substances) that are pinpointed as being responsible for nonoccupational ACD, were, in order of frequency, clothing accessories, cosmetics, topical pharmaceuticals, and clothing. The haptens most frequently recognized as the cause of positive reactions were, in order of frequency, nickel sulphate, fragrance mix, cobalt chloride, balsam of Peru, potassium dichromate, ethylenediamine, and diaminodiphenylmethane.","Epidemiological survey of contact dermatitis in Italy (1984-1993) by GIRDCA (Gruppo Italiano Ricerca Dermatiti da Contatto e Ambientali) Abs: <strong>BACKGROUND: </strong>The Gruppo Italiano Ricerca Dermatiti da Contatto e Ambientali (GIRDCA) resolved to obtain the most relevant data regarding contact dermatitis (CD) in Italy by means of a multicenter epidemiological study, involving research units (RU) throughout the country. The survey was performed with the collaboration of Generale Per l'Informatica, Rome (GEPIN) over the periods 1984 to 1988 and 1989 to 1993. The analytical study (of a transverse kind) was aimed at supplying prevalence measures.<br /><br /><strong>MATERIALS AND METHODS: </strong>The number of subjects taking part in the survey was 42,839. All patients underwent patch testing with the GIRDCA standard series and were included in the survey only if the final diagnosis was either CD or eczematous dermatitis caused by contact. The main anamnestic, clinical data, and allergological test results of all patients were codified into a chart, and subsequently transcribed into a data bank. The data were then processed cumulatively and were statistically analysed by a chi-square for trend test.<br /><br /><strong>RESULTS: </strong>The four most frequent diagnoses (which, when considered together, make up 39,496 cases, or about 92% of all cases) proved to be nonoccupational allergic contact dermatitis (ACD), nonoccupational irritant contact dermatitis (ICD), occupational ACD, and occupational ICD. The haptens most frequently causing positive reactions in the total number of cases over the first 5 years were, in order of frequency: nickel sulphate, potassium dichromate, cobalt chloride, fragrance mix, balsam of Peru, and, in the second 5-year period, nickel sulphate, cobalt chloride, potassium dichromate, fragrance mix, and thimerosal. Occupational CD (ACD and ICD) was present in 11,694 cases overall, corresponding to approximately 27% of the total number of cases examined, and approximately 29% of all CD (including forms of nonoccupational CD). Regarding distribution by sex, a substantial equivalence of males and females for ACD, and a prevalence of females with ICD can be observed. Five occupations were reputed to be responsible for over 60% of total cases of occupational CD (housewives, bricklayers, workers in the metallurgic and mechanical industries, hairdressers, and healthcare personnel). Regarding the pathogenesis, a clearly dominant percentage of ACD may be observed among bricklayers and hairdressers, and of ICD among housewives. The haptens most frequently noted over the entire decade as the cause of positive reaction in occupational ACD were, in order of frequency, potassium dichromate, nickel sulphate, cobalt chloride, p-phenylenediamine and thiuram mix. Nonoccupational CD (ACD and ICD) was present in 27,802 cases overall, corresponding to about 65% of all cases under examination and over 70% of all CD (also including forms of occupational CD). In regard to distribution by sex, a clear dominance of females, as opposed to males, can be noted for ACD and also (although to a lesser extent) for ICD. The main products and materials (ie, components and relative substances) that are pinpointed as being responsible for nonoccupational ACD, were, in order of frequency, clothing accessories, cosmetics, topical pharmaceuticals, and clothing. The haptens most frequently recognized as the cause of positive reactions were, in order of frequency, nickel sulphate, fragrance mix, cobalt chloride, balsam of Peru, potassium dichromate, ethylenediamine, and diaminodiphenylmethane."
1233034,Lestringant et al. 1999,Allergic contact dermatitis in the United Arab Emirates,"<strong>BACKGROUND: </strong>No data exist on allergic contact dermatitis (ACD) in the United Arab Emirates (UAE).<br /><br /><strong>AIM: </strong>Our aim was threefold: (i) to determine the incidence of ACD; (ii) to identify responsible allergens using the European Standard Series, TRUE TEST, and other substances; (iii) to tentatively explore population-specific reactions in Al Ain, UAE.<br /><br /><strong>DESIGN: </strong>This is a prospective, descriptive, hospital-based, study.<br /><br /><strong>SETTING: </strong>Tawam Hospital, Al Ain Medical District, UAE.<br /><br /><strong>PATIENTS: </strong>During the years 1989-1996, 373 patients (male: female = 2 : 3), presenting with cutaneous manifestations possibly related to contact allergy, were patch tested.<br /><br /><strong>RESULTS: </strong>93.8% of patients presented with dermatitis affecting mostly the hands (45.1%), feet (21.4%), face (12.6%), and legs (4.6%). Two hundred and twenty-four patients (60%) (male : female = 1 : 2) tested positive for at least one substance. Nickel was the commonest sensitizer (15%) in both genders. &quot;Fragrance mix&quot; (8%), p-tertiary butylphenolformaldehyde (p-TBPF) resin (7.5%), thiomersal (7.5%), chromium (7.2%), cobalt (6.4%), ethylenediamine (6.4%), neomycin (5.1%), and parabens (5.1%) were prominent allergens. Glutardialdehyde, an additional substance tested together with the European Standard Series, scored significantly (4.8%). Variations from the results reported from other countries may be explained by the specific lifestyles and customs of the UAE population.<br /><br /><strong>CONCLUSIONS: </strong>Substances contained in the TRUE TEST, plus glutardialdehyde, may be considered as the standard series for patch testing in the UAE population.","Allergic contact dermatitis in the United Arab Emirates Abs: <strong>BACKGROUND: </strong>No data exist on allergic contact dermatitis (ACD) in the United Arab Emirates (UAE).<br /><br /><strong>AIM: </strong>Our aim was threefold: (i) to determine the incidence of ACD; (ii) to identify responsible allergens using the European Standard Series, TRUE TEST, and other substances; (iii) to tentatively explore population-specific reactions in Al Ain, UAE.<br /><br /><strong>DESIGN: </strong>This is a prospective, descriptive, hospital-based, study.<br /><br /><strong>SETTING: </strong>Tawam Hospital, Al Ain Medical District, UAE.<br /><br /><strong>PATIENTS: </strong>During the years 1989-1996, 373 patients (male: female = 2 : 3), presenting with cutaneous manifestations possibly related to contact allergy, were patch tested.<br /><br /><strong>RESULTS: </strong>93.8% of patients presented with dermatitis affecting mostly the hands (45.1%), feet (21.4%), face (12.6%), and legs (4.6%). Two hundred and twenty-four patients (60%) (male : female = 1 : 2) tested positive for at least one substance. Nickel was the commonest sensitizer (15%) in both genders. &quot;Fragrance mix&quot; (8%), p-tertiary butylphenolformaldehyde (p-TBPF) resin (7.5%), thiomersal (7.5%), chromium (7.2%), cobalt (6.4%), ethylenediamine (6.4%), neomycin (5.1%), and parabens (5.1%) were prominent allergens. Glutardialdehyde, an additional substance tested together with the European Standard Series, scored significantly (4.8%). Variations from the results reported from other countries may be explained by the specific lifestyles and customs of the UAE population.<br /><br /><strong>CONCLUSIONS: </strong>Substances contained in the TRUE TEST, plus glutardialdehyde, may be considered as the standard series for patch testing in the UAE population."
1232694,Forte et al. 2008,"Metal allergens of growing significance: epidemiology, immunotoxicology, strategies for testing and prevention","Metal-induced allergic contact dermatitis (ACD) is expressed in a wide range of cutaneous reactions following dermal and systemic exposure to products such as cosmetics and tattoos, detergents, jewellery and piercing, leather tanning, articular prostheses and dental implants. Apart from the well known significance of nickel in developing ACD, other metals such as aluminium, beryllium, chromium, cobalt, copper, gold, iridium, mercury, palladium, platinum, rhodium and titanium represented emerging causes of skin hypersensitivity. Despite the European Union directives that limit the total nickel content in jewellery alloys, the water soluble chromium (VI) in cement, and metals banned in cosmetics, the diffusion of metal-induced ACD remained quite high. On this basis, a review on the epidemiology of metal allergens, the types of exposure, the skin penetration, the immune response, and the protein interaction is motivated. Moreover, in vivo and in vitro tests for the identification and potency of skin-sensitizing metals are here reviewed in a risk assessment framework for the protection of consumer's health. Avenues for ACD prevention and therapy such as observance of maximum allowable metal levels, optimization of metallurgic characteristics, efficacy of chelating agents and personal protection are also discussed.","Metal allergens of growing significance: epidemiology, immunotoxicology, strategies for testing and prevention Abs: Metal-induced allergic contact dermatitis (ACD) is expressed in a wide range of cutaneous reactions following dermal and systemic exposure to products such as cosmetics and tattoos, detergents, jewellery and piercing, leather tanning, articular prostheses and dental implants. Apart from the well known significance of nickel in developing ACD, other metals such as aluminium, beryllium, chromium, cobalt, copper, gold, iridium, mercury, palladium, platinum, rhodium and titanium represented emerging causes of skin hypersensitivity. Despite the European Union directives that limit the total nickel content in jewellery alloys, the water soluble chromium (VI) in cement, and metals banned in cosmetics, the diffusion of metal-induced ACD remained quite high. On this basis, a review on the epidemiology of metal allergens, the types of exposure, the skin penetration, the immune response, and the protein interaction is motivated. Moreover, in vivo and in vitro tests for the identification and potency of skin-sensitizing metals are here reviewed in a risk assessment framework for the protection of consumer's health. Avenues for ACD prevention and therapy such as observance of maximum allowable metal levels, optimization of metallurgic characteristics, efficacy of chelating agents and personal protection are also discussed."
1232530,Arrandale et al. 2012,Occupational contact allergens: are they also associated with occupational asthma?,"<strong>BACKGROUND: </strong>Workplace exposures that can potentially cause both allergic occupational contact dermatitis (AOCD) and occupational asthma (OA) are not clearly identified.<br /><br /><strong>METHODS: </strong>Occupational contact allergens (OCAs) were identified using North American Contact Dermatitis Group (NACDG) data. Reference documents and systematic reviews were used to determine whether each OCA had been reported to potentially cause OA. The presence or absence of a sensitizer notation in occupational hygiene reference documents was also examined.<br /><br /><strong>RESULTS: </strong>The 10 most common OCAs were: epoxy resin*, thiuram, carba mix, nickel sulfate*, cobalt chloride*, potassium dichromate*, glyceryl thioglycolate, p-phenylenediamine*, formaldehyde* and glutaraldehyde*. Seven (indicated by *) were determined to be possible causes of OA. Information on sensitizing potential from OH reference materials contained conflicting information.<br /><br /><strong>CONCLUSIONS: </strong>Several common OCAs can also potentially cause OA. Inhalation and dermal exposures to these agents should be controlled and both OA and AOCD should be considered as possible health outcomes. Increased consistency in sensitizer notations is needed.","Occupational contact allergens: are they also associated with occupational asthma? Abs: <strong>BACKGROUND: </strong>Workplace exposures that can potentially cause both allergic occupational contact dermatitis (AOCD) and occupational asthma (OA) are not clearly identified.<br /><br /><strong>METHODS: </strong>Occupational contact allergens (OCAs) were identified using North American Contact Dermatitis Group (NACDG) data. Reference documents and systematic reviews were used to determine whether each OCA had been reported to potentially cause OA. The presence or absence of a sensitizer notation in occupational hygiene reference documents was also examined.<br /><br /><strong>RESULTS: </strong>The 10 most common OCAs were: epoxy resin*, thiuram, carba mix, nickel sulfate*, cobalt chloride*, potassium dichromate*, glyceryl thioglycolate, p-phenylenediamine*, formaldehyde* and glutaraldehyde*. Seven (indicated by *) were determined to be possible causes of OA. Information on sensitizing potential from OH reference materials contained conflicting information.<br /><br /><strong>CONCLUSIONS: </strong>Several common OCAs can also potentially cause OA. Inhalation and dermal exposures to these agents should be controlled and both OA and AOCD should be considered as possible health outcomes. Increased consistency in sensitizer notations is needed."
1232527,Wang et al. 2011,Occupational hand dermatitis among cement workers in Taiwan,"<strong>BACKGROUND/PURPOSE: </strong>Occupational dermatitis among cement workers is a major occupational health concern. The two most important occupational hazards for cement workers are irritant and allergic cement contact dermatitis. The objective of this study was to investigate the severity of occupational cement contact dermatitis and the common allergens among cement workers in Taiwan.<br /><br /><strong>METHODS: </strong>A total of 97 cement workers from the Cement Workers' Association of Tainan City and County participated in this study. A structured questionnaire was used to evaluate the demographic data and work-related activities of these cement workers. A complete skin examination was conducted, and skin manifestations were assessed by a dermatologist. Allergens from European Standard Tray (Chemotechnique Diagnostic AB, Sweden) with a total of 25 substances were used for patch testing.<br /><br /><strong>RESULTS: </strong>Our results showed that 65 out of 97 cement workers were suffering from occupational cement hand contact dermatitis. The most affected skin area was the hand. Thickening of the dorsal surface of the hand, especially around the metacarpophalangeal joint area, and hyperkeratosis of the palm were the major skin manifestations. The results of the patch test showed that 24 out of 97 were allergic to potassium dichromate, nine were allergic to thiuram mix, nine were allergic to fragrance mix and seven were allergic to cobalt chloride. The final diagnosis, based on the results of the skin examination and the patch test, showed that 43 of 97 cement workers had irritant cement contact dermatitis and 22 had allergic cement contact dermatitis.<br /><br /><strong>CONCLUSION: </strong>We conclude that occupational cement hand dermatitis among cement workers is an important and severe issue in Taiwan, and the most common allergens among cement workers are potassium dichromate, thiuram mix, fragrance mix and cobalt chloride. The high positive rate of chromium hypersensitivity among cement workers reflects the urgency to regulate the addition of ferrous sulfate to cement in Taiwan.","Occupational hand dermatitis among cement workers in Taiwan Abs: <strong>BACKGROUND/PURPOSE: </strong>Occupational dermatitis among cement workers is a major occupational health concern. The two most important occupational hazards for cement workers are irritant and allergic cement contact dermatitis. The objective of this study was to investigate the severity of occupational cement contact dermatitis and the common allergens among cement workers in Taiwan.<br /><br /><strong>METHODS: </strong>A total of 97 cement workers from the Cement Workers' Association of Tainan City and County participated in this study. A structured questionnaire was used to evaluate the demographic data and work-related activities of these cement workers. A complete skin examination was conducted, and skin manifestations were assessed by a dermatologist. Allergens from European Standard Tray (Chemotechnique Diagnostic AB, Sweden) with a total of 25 substances were used for patch testing.<br /><br /><strong>RESULTS: </strong>Our results showed that 65 out of 97 cement workers were suffering from occupational cement hand contact dermatitis. The most affected skin area was the hand. Thickening of the dorsal surface of the hand, especially around the metacarpophalangeal joint area, and hyperkeratosis of the palm were the major skin manifestations. The results of the patch test showed that 24 out of 97 were allergic to potassium dichromate, nine were allergic to thiuram mix, nine were allergic to fragrance mix and seven were allergic to cobalt chloride. The final diagnosis, based on the results of the skin examination and the patch test, showed that 43 of 97 cement workers had irritant cement contact dermatitis and 22 had allergic cement contact dermatitis.<br /><br /><strong>CONCLUSION: </strong>We conclude that occupational cement hand dermatitis among cement workers is an important and severe issue in Taiwan, and the most common allergens among cement workers are potassium dichromate, thiuram mix, fragrance mix and cobalt chloride. The high positive rate of chromium hypersensitivity among cement workers reflects the urgency to regulate the addition of ferrous sulfate to cement in Taiwan."
1232515,Krecisz et al. ,Contact allergy to metals in adolescents. Nickel release from metal accessories 7 years after the implementation of the EU Nickel Directive in Poland,"Background. Contact allergy among adolescents is an important issue. Objectives. To assess the prevalence of contact allergy to metals in adolescents aged 15 years and nickel release from metal accessories that are in direct contact with the skin. Methods. Three hundred and nine females and 219 males, all 15 years old, from randomly selected secondary schools were examined and patch tested with nickel sulfate, cobalt chloride, palladium chloride, and potassium dichromate. Three hundred and ninety-nine metal accessories were tested with the dimethylglyoxime (DMG) test. Results.'Metal dermatitis' was reported by 19.4% of females and 0.5% of males. Positive patch test reactions were found in 8.5% of the adolescents (12.9% in females; 2.3% in males), namely to: nickel (12.3% of females; 1.4% of males); palladium (5.2% of females; 0.5% of males); cobalt (3.2% of females; 1.4% of males); and chromium (1.3% of females; 0.9% of males). Allergic contact dermatitis caused by metals was diagnosed in 9.7% of females and in 0.5% of males. Of the metal items, 26.1% gave positive DMG test results: 10.0% of earrings, 11.4% of snaps, and 56.2% of belt buckles. Conclusions. Despite the implementation of the Nickel Directive in Poland, nickel still remains an important causal factor for allergic contact dermatitis. Numerous metal accessories do not comply with the Directive.","Contact allergy to metals in adolescents. Nickel release from metal accessories 7 years after the implementation of the EU Nickel Directive in Poland Abs: Background. Contact allergy among adolescents is an important issue. Objectives. To assess the prevalence of contact allergy to metals in adolescents aged 15 years and nickel release from metal accessories that are in direct contact with the skin. Methods. Three hundred and nine females and 219 males, all 15 years old, from randomly selected secondary schools were examined and patch tested with nickel sulfate, cobalt chloride, palladium chloride, and potassium dichromate. Three hundred and ninety-nine metal accessories were tested with the dimethylglyoxime (DMG) test. Results.'Metal dermatitis' was reported by 19.4% of females and 0.5% of males. Positive patch test reactions were found in 8.5% of the adolescents (12.9% in females; 2.3% in males), namely to: nickel (12.3% of females; 1.4% of males); palladium (5.2% of females; 0.5% of males); cobalt (3.2% of females; 1.4% of males); and chromium (1.3% of females; 0.9% of males). Allergic contact dermatitis caused by metals was diagnosed in 9.7% of females and in 0.5% of males. Of the metal items, 26.1% gave positive DMG test results: 10.0% of earrings, 11.4% of snaps, and 56.2% of belt buckles. Conclusions. Despite the implementation of the Nickel Directive in Poland, nickel still remains an important causal factor for allergic contact dermatitis. Numerous metal accessories do not comply with the Directive."
1232230,Nomiyama et al. 1980,"Normal chromium levels in urine and blood of Japanese subjects determined by direct flameless atomic absorption spectrophotometry, and valency of chromium in urine after exposure to hexavalent chromium",Two hundred and thirty one urine and 20 blood samples of Japanese subjects from 4 geographic areas without known chromium pollution were assayed for chromium by direct flameless atomic absorption spectrophotometry. Normal chromium level in urine of Japanese subjects was 0.41 microg/L on an average. Urine level was less than 0.8 microg/L for all age and sex groups. Chromium levels in 2 hour urines did not correlate with those in 24 hours urine. Blood level of chromium was 2.9 ng/mL. A rabbit given an oral administration of 100 mg hexavalent chromium excreted 8.2 mg in 15 days after administration. No hexavalent chromium could be detected in urine. Ninety percent of the urinary excretion occurred within 2 days of administration.,"Normal chromium levels in urine and blood of Japanese subjects determined by direct flameless atomic absorption spectrophotometry, and valency of chromium in urine after exposure to hexavalent chromium Abs: Two hundred and thirty one urine and 20 blood samples of Japanese subjects from 4 geographic areas without known chromium pollution were assayed for chromium by direct flameless atomic absorption spectrophotometry. Normal chromium level in urine of Japanese subjects was 0.41 microg/L on an average. Urine level was less than 0.8 microg/L for all age and sex groups. Chromium levels in 2 hour urines did not correlate with those in 24 hours urine. Blood level of chromium was 2.9 ng/mL. A rabbit given an oral administration of 100 mg hexavalent chromium excreted 8.2 mg in 15 days after administration. No hexavalent chromium could be detected in urine. Ninety percent of the urinary excretion occurred within 2 days of administration."
1232229,Pepi and  Baldi 1992,Modulation of chromium(VI) toxicity by organic and inorganic sulfur species in yeasts from industrial wastes,"Two chromium(VI) resistant yeast strains (Candida sp. and Rhodosporidium sp.) were isolated from industrial wastes. Four different yeasts, three from the Industrial Yeast Collection and one of pharmaceutical origin, were also studied in relation to chromate toxicity and its alleviation by sulfur species. The growth of yeasts from industrial wastes was inhibited by 50% by high concentrations of Cr(VI): Candida sp. by 4 mM Cr(VI) and Rhodosporidium sp. by 10 mM Cr(VI) in Sabouraud Broth medium. The other Cr(VI)-sensitive yeasts were inhibited by 0.1 mM Cr(VI). The general mechanism of chromium resistance in Candida sp. and Rhodosporidium sp. was due to reduced uptake of chromium, but not to biological reduction from Cr(VI) to Cr(III). In Cr(VI)-sensitive yeasts, chromium was accumulated as much as 10-fold, as in Saccharomyces cerevisiae. Cr(VI) toxicity in Candida sp. was modulated from Cr(VI)-resistance to Cr(VI)-hypersensitivity depending on the addition of methionine, cysteine, sulfate and djenkolic acid. If Candida sp. was grown in the presence of S-amino acids, especially methionine, it was more resistant than if the sulfur source was sulfate. When sulfate transport was enhanced by addition of djenkolic acid, Candida sp. became hypersensitive. Rhosporidium sp. was always resistant to Cr(VI) because sulfate transport was inefficient and it assimilated sulfur as S-amino acids. Cr(VI)-sensitive yeasts required larger amounts of S-amino acids, especially methionine, to tolerate Cr(VI) toxicity. Cysteine was toxic for C.famata 6016 above 50 microM.","Modulation of chromium(VI) toxicity by organic and inorganic sulfur species in yeasts from industrial wastes Abs: Two chromium(VI) resistant yeast strains (Candida sp. and Rhodosporidium sp.) were isolated from industrial wastes. Four different yeasts, three from the Industrial Yeast Collection and one of pharmaceutical origin, were also studied in relation to chromate toxicity and its alleviation by sulfur species. The growth of yeasts from industrial wastes was inhibited by 50% by high concentrations of Cr(VI): Candida sp. by 4 mM Cr(VI) and Rhodosporidium sp. by 10 mM Cr(VI) in Sabouraud Broth medium. The other Cr(VI)-sensitive yeasts were inhibited by 0.1 mM Cr(VI). The general mechanism of chromium resistance in Candida sp. and Rhodosporidium sp. was due to reduced uptake of chromium, but not to biological reduction from Cr(VI) to Cr(III). In Cr(VI)-sensitive yeasts, chromium was accumulated as much as 10-fold, as in Saccharomyces cerevisiae. Cr(VI) toxicity in Candida sp. was modulated from Cr(VI)-resistance to Cr(VI)-hypersensitivity depending on the addition of methionine, cysteine, sulfate and djenkolic acid. If Candida sp. was grown in the presence of S-amino acids, especially methionine, it was more resistant than if the sulfur source was sulfate. When sulfate transport was enhanced by addition of djenkolic acid, Candida sp. became hypersensitive. Rhosporidium sp. was always resistant to Cr(VI) because sulfate transport was inefficient and it assimilated sulfur as S-amino acids. Cr(VI)-sensitive yeasts required larger amounts of S-amino acids, especially methionine, to tolerate Cr(VI) toxicity. Cysteine was toxic for C.famata 6016 above 50 microM."
1232228,Sheehan et al. 1992,Field evaluation of a sampling and analytical method for environmental levels of airborne hexavalent chromium,"Hexavalent chromium, Cr(VI), has been classified as a human respiratory carcinogen. Airborne Cr(VI) emissions are associated with a number of industrial sources including metal plating, tanning, chromite ore processing, and spray painting operations; combustion sources such as automobiles and incinerators; and fugitive dusts from contaminated soil. There has been considerable interest within industry and the regulatory community to assess the potential cancer risks of workers exposed to Cr(VI) at levels substantially below the threshold limit value (TLV) of 50 micrograms/m3. To date, only the workplace sampling and analytical method (National Institute for Occupational Safety and Health [NIOSH] Method 7600) has been validated for measuring airborne Cr(VI), and it can accurately measure concentrations only as low as 500 ng/m3. This paper describes the field evaluation of a sampling and analytical method for the quantitation of airborne Cr(VI) at concentrations 5000 times lower than the current standard method (as low as 0.1 ng/m3). The collection method uses three 500-mL Greenberg-Smith impingers in series, operated at 15 Lpm for 24 hr. All three impingers are filled with 200 mL of a slightly alkaline (pH approximately 8) sodium bicarbonate buffer solution. The results of validation tests showed that both Cr(VI) and trivalent chromium, Cr(III), were stable in the collection medium and that samples may be stored for up to 100 days without appreciable loss of Cr(VI). Method precision based on the pooled coefficient of variation for replicate samples was 10.4%, and method accuracy based on the mean percent recovery of spiked samples was 94%. Both the precision and accuracy of the impinger method were within NIOSH criteria. This method could be used to measure ambient concentrations of Cr(VI) in the workplace caused by fugitive emissions from manufacturing processes or chromium-contaminated soils at workplace concentrations well below the current TLV (50 micrograms/m3) or permissible exposure limit (100 micrograms/m3).","Field evaluation of a sampling and analytical method for environmental levels of airborne hexavalent chromium Abs: Hexavalent chromium, Cr(VI), has been classified as a human respiratory carcinogen. Airborne Cr(VI) emissions are associated with a number of industrial sources including metal plating, tanning, chromite ore processing, and spray painting operations; combustion sources such as automobiles and incinerators; and fugitive dusts from contaminated soil. There has been considerable interest within industry and the regulatory community to assess the potential cancer risks of workers exposed to Cr(VI) at levels substantially below the threshold limit value (TLV) of 50 micrograms/m3. To date, only the workplace sampling and analytical method (National Institute for Occupational Safety and Health [NIOSH] Method 7600) has been validated for measuring airborne Cr(VI), and it can accurately measure concentrations only as low as 500 ng/m3. This paper describes the field evaluation of a sampling and analytical method for the quantitation of airborne Cr(VI) at concentrations 5000 times lower than the current standard method (as low as 0.1 ng/m3). The collection method uses three 500-mL Greenberg-Smith impingers in series, operated at 15 Lpm for 24 hr. All three impingers are filled with 200 mL of a slightly alkaline (pH approximately 8) sodium bicarbonate buffer solution. The results of validation tests showed that both Cr(VI) and trivalent chromium, Cr(III), were stable in the collection medium and that samples may be stored for up to 100 days without appreciable loss of Cr(VI). Method precision based on the pooled coefficient of variation for replicate samples was 10.4%, and method accuracy based on the mean percent recovery of spiked samples was 94%. Both the precision and accuracy of the impinger method were within NIOSH criteria. This method could be used to measure ambient concentrations of Cr(VI) in the workplace caused by fugitive emissions from manufacturing processes or chromium-contaminated soils at workplace concentrations well below the current TLV (50 micrograms/m3) or permissible exposure limit (100 micrograms/m3)."
1232227,Ernst and  Bonde 1992,Sex hormones and epididymal sperm parameters in rats following sub-chronic treatment with hexavalent chromium,"Testicular atrophy and reduced epididymal sperm count are known to occur after i.p. administration of high doses of hexavalent chromium to rats. The effect of 0.5 mg kg-1 hexavalent chromium injected i.p. 5 d a week for 8 weeks was investigated in male Wistar rats. A significant reduction in epididymal sperm motility was found at the end of the exposure period. The reduction was reversed after an unexposed period of a further 8 weeks. In addition, a decrease in serum testosterone and an increase in FSH were found at the end of the exposure period. The results indicate that a number of mechanisms may be involved in the deleterious effects of chromate on male fecundity.","Sex hormones and epididymal sperm parameters in rats following sub-chronic treatment with hexavalent chromium Abs: Testicular atrophy and reduced epididymal sperm count are known to occur after i.p. administration of high doses of hexavalent chromium to rats. The effect of 0.5 mg kg-1 hexavalent chromium injected i.p. 5 d a week for 8 weeks was investigated in male Wistar rats. A significant reduction in epididymal sperm motility was found at the end of the exposure period. The reduction was reversed after an unexposed period of a further 8 weeks. In addition, a decrease in serum testosterone and an increase in FSH were found at the end of the exposure period. The results indicate that a number of mechanisms may be involved in the deleterious effects of chromate on male fecundity."
1232226,Bonde and  Ernst 1992,Sex hormones and semen quality in welders exposed to hexavalent chromium,"Recent experimental studies in rodents document the spermatotoxic effects of water-soluble hexavalent chromium. Welders comprise, worldwide, a major occupational group with acknowledged exposure to chromium. This study examines the relationship between semen quality and chromium in the urine and blood of a population of 30 tungsten inert gas (TIG) stainless steel welders, 30 mild steel welders and 47 non-welding workers. Each subject provided two to three semen samples. The chromium concentration ranged from 0.17 to 4.74 nmol mmol1 creatinine (median 1.08) in post-shift spot urine and from 6.0 to 46.4 nmol l-1 in blood. None of several semen parameters deteriorated with increasing level of internal exposure to chromium. Low-level exposure to hexavalent chromium associated with TIG stainless steel and mild steel welding do not appear to be a major hazard for human spermatogenesis.","Sex hormones and semen quality in welders exposed to hexavalent chromium Abs: Recent experimental studies in rodents document the spermatotoxic effects of water-soluble hexavalent chromium. Welders comprise, worldwide, a major occupational group with acknowledged exposure to chromium. This study examines the relationship between semen quality and chromium in the urine and blood of a population of 30 tungsten inert gas (TIG) stainless steel welders, 30 mild steel welders and 47 non-welding workers. Each subject provided two to three semen samples. The chromium concentration ranged from 0.17 to 4.74 nmol mmol1 creatinine (median 1.08) in post-shift spot urine and from 6.0 to 46.4 nmol l-1 in blood. None of several semen parameters deteriorated with increasing level of internal exposure to chromium. Low-level exposure to hexavalent chromium associated with TIG stainless steel and mild steel welding do not appear to be a major hazard for human spermatogenesis."
1232225,Turk and  Rietschel 1993,Effect of processing cement to concrete on hexavalent chromium levels,"Hexavalent chromium sensitization is known to occur from exposure to cement. Concrete is a mixture of cement, sand, rock, and water. Admixtures are compounds used to retard or accelerate concrete setting time. Some countries use ferrous sulfate to reduce hexavalent chromium in cement. We evaluated and compared hexavalent chromium levels in cement, rock (aggregate), and wet and dry concrete in samples from Singapore, Ireland, Denmark, Australia, and the United States. Cement from Denmark contains ferrous sulfate. The effect of representative admixtures on hexavalent chromium concentration in concrete was also evaluated, but technical limitations made evaluation difficult. Soluble chromium levels in cement ranged from 0.225 mg/kg in the US sample to 0.036 mg/kg in the Singapore sample. Aggregate chromium levels ranged from 0.083 mg/kg in the Denmark sample to &lt; 0.002 mg/kg in the Ireland sample. Fresh US concrete, with 1.27 mg/kg hexavalent chromium, contained the highest level. The Denmark sample, with ferrous sulfate added, was lowest (&lt; 0.01 mg/kg). Hardened concrete levels ranged from 0.104 mg/kg from the Ireland sample to 0.002 mg/kg from the Singapore sample. Therefore, hexavalent chromium levels do appear to be influenced by admixtures and by processing from powdered cement to dry concrete. Ferrous sulfate significantly reduced hexavalent chromium levels in fresh cement.","Effect of processing cement to concrete on hexavalent chromium levels Abs: Hexavalent chromium sensitization is known to occur from exposure to cement. Concrete is a mixture of cement, sand, rock, and water. Admixtures are compounds used to retard or accelerate concrete setting time. Some countries use ferrous sulfate to reduce hexavalent chromium in cement. We evaluated and compared hexavalent chromium levels in cement, rock (aggregate), and wet and dry concrete in samples from Singapore, Ireland, Denmark, Australia, and the United States. Cement from Denmark contains ferrous sulfate. The effect of representative admixtures on hexavalent chromium concentration in concrete was also evaluated, but technical limitations made evaluation difficult. Soluble chromium levels in cement ranged from 0.225 mg/kg in the US sample to 0.036 mg/kg in the Singapore sample. Aggregate chromium levels ranged from 0.083 mg/kg in the Denmark sample to &lt; 0.002 mg/kg in the Ireland sample. Fresh US concrete, with 1.27 mg/kg hexavalent chromium, contained the highest level. The Denmark sample, with ferrous sulfate added, was lowest (&lt; 0.01 mg/kg). Hardened concrete levels ranged from 0.104 mg/kg from the Ireland sample to 0.002 mg/kg from the Singapore sample. Therefore, hexavalent chromium levels do appear to be influenced by admixtures and by processing from powdered cement to dry concrete. Ferrous sulfate significantly reduced hexavalent chromium levels in fresh cement."
1232224,Gillies 1993,Dermatitis on construction sites,,Dermatitis on construction sites Abs: 
1232223,Hneihen et al. 1993,Differential binding of chromium(VI) and chromium(III) complexes to salmon sperm nuclei and nuclear DNA and isolated calf thymus DNA,"The binding of CrCl3.6H2O, Cr(NO3)3.9H2O, [Cr(L-His)2] (NO3)3.H2O, [Cr(L-Cys)(L-His)].3.5H2O, [Cr(L-His)(D-Pen)].H2O, Na[Cr(L-Cys)2].2H2O, K2[Cr(GS)2].3H2O, Na2-CrO4.4H2O, and Na2Cr2O7.2H2O to salmon sperm nuclei and nuclear DNA was determined. The Cr(III)-amino acid complexes and Cr(VI) exhibited significantly lower Cr-nuclei and Cr-DNA binding levels relative to the inorganic complexes CrCl3.6H2O and Cr(NO3)3.9H2O. The binding of CrCl3.6H2O, Cr(NO3)3.9H2O and Na2Cr2O7.2H2O to salmon sperm nuclei and nuclear DNA in the presence of rat lung cytosol was determined under the same conditions. For those complexes studied in both buffer and cytosol, the Cr-DNA binding levels for Cr(III) complexes were higher in buffer than in cytosol, while a relatively higher binding level was observed for Cr(VI) in cytosol than in buffer. Slightly lower nuclear protein levels were present in Cr(VI) incubations than in Cr(III) incubations with nuclei both in the presence and the absence of cytosol. The relative binding of CrCl3.6H2O, Cr(NO3)3.9H2O, [Cr(L-His)2](NO)3.H2O, [Cr(L-Cys) (L-His)].3.5H2O, [Cr(L-His)(D-Pen)].H2O, Na[Cr(L-Cys)2].2H2O and Na2CrO4.4H2O to isolated calf thymus DNA in buffer was also determined. Positively charged, labile inorganic Cr(III) complexes, CrCl3.6H2O and Cr(NO3)3.9H2O, exhibited higher binding to DNA than [Cr(L-His) (D-Pen)].H2O, and no binding to DNA was observed with Cr(VI) and the other neutral, positively and negatively charged, inert Cr(III)-amino acid complexes. Although labile aquo chromium(III) complexes are quite reactive with DNA, the reactivity of chromium(III), formed upon intracellular reduction of carcinogenic chromium(VI), toward DNA will be diminished by complexation with cellular proteins, peptides and amino acids.","Differential binding of chromium(VI) and chromium(III) complexes to salmon sperm nuclei and nuclear DNA and isolated calf thymus DNA Abs: The binding of CrCl3.6H2O, Cr(NO3)3.9H2O, [Cr(L-His)2] (NO3)3.H2O, [Cr(L-Cys)(L-His)].3.5H2O, [Cr(L-His)(D-Pen)].H2O, Na[Cr(L-Cys)2].2H2O, K2[Cr(GS)2].3H2O, Na2-CrO4.4H2O, and Na2Cr2O7.2H2O to salmon sperm nuclei and nuclear DNA was determined. The Cr(III)-amino acid complexes and Cr(VI) exhibited significantly lower Cr-nuclei and Cr-DNA binding levels relative to the inorganic complexes CrCl3.6H2O and Cr(NO3)3.9H2O. The binding of CrCl3.6H2O, Cr(NO3)3.9H2O and Na2Cr2O7.2H2O to salmon sperm nuclei and nuclear DNA in the presence of rat lung cytosol was determined under the same conditions. For those complexes studied in both buffer and cytosol, the Cr-DNA binding levels for Cr(III) complexes were higher in buffer than in cytosol, while a relatively higher binding level was observed for Cr(VI) in cytosol than in buffer. Slightly lower nuclear protein levels were present in Cr(VI) incubations than in Cr(III) incubations with nuclei both in the presence and the absence of cytosol. The relative binding of CrCl3.6H2O, Cr(NO3)3.9H2O, [Cr(L-His)2](NO)3.H2O, [Cr(L-Cys) (L-His)].3.5H2O, [Cr(L-His)(D-Pen)].H2O, Na[Cr(L-Cys)2].2H2O and Na2CrO4.4H2O to isolated calf thymus DNA in buffer was also determined. Positively charged, labile inorganic Cr(III) complexes, CrCl3.6H2O and Cr(NO3)3.9H2O, exhibited higher binding to DNA than [Cr(L-His) (D-Pen)].H2O, and no binding to DNA was observed with Cr(VI) and the other neutral, positively and negatively charged, inert Cr(III)-amino acid complexes. Although labile aquo chromium(III) complexes are quite reactive with DNA, the reactivity of chromium(III), formed upon intracellular reduction of carcinogenic chromium(VI), toward DNA will be diminished by complexation with cellular proteins, peptides and amino acids."
1232222,Dillon et al. 1993,In vitro DNA damage and mutations induced by a macrocyclic tetraamide chromium(V) complex: Implications for the role of Cr(V) peptide complexes in chromium-induced cancers,"Electron paramagnetic resonance and electronic absorption spectroscopies have shown that unlike the bidentate Cr(V) complex [Cr(ehba)2O]- (ehba = 2-hydroxy-2-ethylbutanoato(2-)), I, the macrocyclic tetradentate complex, [Cr (mampa-dcb)(O)]- (mampa-dcb = 5,6-(4,5-dichlorobenzo)-3,8,11,13-tetraoxo-2,2,9,9-tetrameth yl-12,12-diethyl-1, 4,7,10-tetraazacyclotridecane), II, is substitutionally inert. Low levels of DNA strand cleavage were observed after treatment with II under physiological conditions (50 mM sodium phosphate, pH 7.4, 37 degrees C) at concentrations as high as 2 mM for periods as long as 2 days. II also induces a lower number of revertants in mutation assays with Salmonella typhimurium TA100 than I when identical Cr concentrations are applied. The slopes of the linear portion of the dose-response curves are parallel, however, indicating that the mutagenicity of II is comparable to I. II is stable toward ligand exchange, reduction and disproportionation in the mutagenicity test medium and also in the presence of bacteria and the common cell reductant, glutathione. This indicates that ligand exchange with DNA and/or reduction to Cr(IV) are not responsible for the mutagenicity of II (unlike I). It is believed that II reversibly but weakly intercalates with DNA placing the Cr(V) center in close proximity for hydrogen atom abstraction or oxo-transfer reactions to ensure. This tetraamide complex is a good structural and biomimetic model for non-sulfur-containing Cr(V) peptide species that may form in vivo from reactions of Cr(VI) with peptides. Hence, it is likely to be relevant to understanding one possible mechanism by which Cr(VI) causes cancer.","In vitro DNA damage and mutations induced by a macrocyclic tetraamide chromium(V) complex: Implications for the role of Cr(V) peptide complexes in chromium-induced cancers Abs: Electron paramagnetic resonance and electronic absorption spectroscopies have shown that unlike the bidentate Cr(V) complex [Cr(ehba)2O]- (ehba = 2-hydroxy-2-ethylbutanoato(2-)), I, the macrocyclic tetradentate complex, [Cr (mampa-dcb)(O)]- (mampa-dcb = 5,6-(4,5-dichlorobenzo)-3,8,11,13-tetraoxo-2,2,9,9-tetrameth yl-12,12-diethyl-1, 4,7,10-tetraazacyclotridecane), II, is substitutionally inert. Low levels of DNA strand cleavage were observed after treatment with II under physiological conditions (50 mM sodium phosphate, pH 7.4, 37 degrees C) at concentrations as high as 2 mM for periods as long as 2 days. II also induces a lower number of revertants in mutation assays with Salmonella typhimurium TA100 than I when identical Cr concentrations are applied. The slopes of the linear portion of the dose-response curves are parallel, however, indicating that the mutagenicity of II is comparable to I. II is stable toward ligand exchange, reduction and disproportionation in the mutagenicity test medium and also in the presence of bacteria and the common cell reductant, glutathione. This indicates that ligand exchange with DNA and/or reduction to Cr(IV) are not responsible for the mutagenicity of II (unlike I). It is believed that II reversibly but weakly intercalates with DNA placing the Cr(V) center in close proximity for hydrogen atom abstraction or oxo-transfer reactions to ensure. This tetraamide complex is a good structural and biomimetic model for non-sulfur-containing Cr(V) peptide species that may form in vivo from reactions of Cr(VI) with peptides. Hence, it is likely to be relevant to understanding one possible mechanism by which Cr(VI) causes cancer."
1232218,Wainman et al. 1994,The extractability of Cr(VI) from contaminated soil in synthetic sweat,"Hexavalent chromium is a common skin irritant that can cause contact dermatitis in sensitized individuals. Soil samples from two chromium waste sites having different Cr(VI) concentrations were extracted in synthetic sweat solutions over a pH range of 4 to 8 and analyzed for Cr(VI). These extractions were performed to determine the potential availability of Cr(VI) from contaminated soils upon contact with human sweat. The samples were also extracted using the EPA Method 3060 alkaline digestion. Overall, hexavalent chromium was readily extractable from both samples in the solutions tested. One of the samples contained Cr(VI) crystals, known as blooms, and had a Cr(VI) concentration approximately 40 times greater than the sample without blooms. The pH of the synthetic sweat solution had little effect on the Cr(VI) concentration determined for the sample containing blooms, whereas the Cr(VI) concentration determined for the sample without blooms increased with increasing pH. The Cr(VI) extracted in the synthetic sweat solutions was consistently lower than the amount extracted by the EPA 3060 alkaline extraction.","The extractability of Cr(VI) from contaminated soil in synthetic sweat Abs: Hexavalent chromium is a common skin irritant that can cause contact dermatitis in sensitized individuals. Soil samples from two chromium waste sites having different Cr(VI) concentrations were extracted in synthetic sweat solutions over a pH range of 4 to 8 and analyzed for Cr(VI). These extractions were performed to determine the potential availability of Cr(VI) from contaminated soils upon contact with human sweat. The samples were also extracted using the EPA Method 3060 alkaline digestion. Overall, hexavalent chromium was readily extractable from both samples in the solutions tested. One of the samples contained Cr(VI) crystals, known as blooms, and had a Cr(VI) concentration approximately 40 times greater than the sample without blooms. The pH of the synthetic sweat solution had little effect on the Cr(VI) concentration determined for the sample containing blooms, whereas the Cr(VI) concentration determined for the sample without blooms increased with increasing pH. The Cr(VI) extracted in the synthetic sweat solutions was consistently lower than the amount extracted by the EPA 3060 alkaline extraction."
1232217,Pastides et al. 1994,A retrospective-cohort study of occupational exposure to hexavalent chromium,"A retrospective cohort study was conducted to examine the risk of mortality, cancer, and other adverse health outcomes, at the United States' largest chromate chemicals manufacturing facility in Castle Hayne, North Carolina. This facility, built in 1971, was designed to reduce the high levels of chromium exposure found at most older facilities. Exposure assessment was based on analysis of more than 5,000 personal breathing zone samples collected over a 15-year period. A questionnaire was used to collect relevant occupational, medical, smoking, and other information from current and former employees. Analysis of the cohort's mortality experience found no substantial departures from that expected based on external comparisons, although evidence of a healthy worker effect was observed. Internal cohort analyses were limited by relatively small numbers; however, a subgroup of employees who transferred from older facilities was found to have higher risks of mortality (odds ratio = 1.27 for each 3 years of previous exposure; 90% confidence interval (CI) = 1.07-1.51) and cancer (odds ratio = 1.22 for each 3 years of previous exposure; 90% CI = 1.03-1.45). While this subgroup represented only 11% of the individuals in this study, they accounted for 46% (6/13) of all observed cancers (excluding skin cancers) and 60% (3/5) of lung cancers. There was no increased risk of mortality or cancer among employees who worked only at the newer facility. As an etiologic research study, the results are limited by the relatively small number of subjects and short follow-up; nevertheless, the findings can be used to design and implement a prospective surveillance system for monitoring the health of chromate production workers.","A retrospective-cohort study of occupational exposure to hexavalent chromium Abs: A retrospective cohort study was conducted to examine the risk of mortality, cancer, and other adverse health outcomes, at the United States' largest chromate chemicals manufacturing facility in Castle Hayne, North Carolina. This facility, built in 1971, was designed to reduce the high levels of chromium exposure found at most older facilities. Exposure assessment was based on analysis of more than 5,000 personal breathing zone samples collected over a 15-year period. A questionnaire was used to collect relevant occupational, medical, smoking, and other information from current and former employees. Analysis of the cohort's mortality experience found no substantial departures from that expected based on external comparisons, although evidence of a healthy worker effect was observed. Internal cohort analyses were limited by relatively small numbers; however, a subgroup of employees who transferred from older facilities was found to have higher risks of mortality (odds ratio = 1.27 for each 3 years of previous exposure; 90% confidence interval (CI) = 1.07-1.51) and cancer (odds ratio = 1.22 for each 3 years of previous exposure; 90% CI = 1.03-1.45). While this subgroup represented only 11% of the individuals in this study, they accounted for 46% (6/13) of all observed cancers (excluding skin cancers) and 60% (3/5) of lung cancers. There was no increased risk of mortality or cancer among employees who worked only at the newer facility. As an etiologic research study, the results are limited by the relatively small number of subjects and short follow-up; nevertheless, the findings can be used to design and implement a prospective surveillance system for monitoring the health of chromate production workers."
1232213,Al-Sabti et al. 1994,Chromium-induced micronuclei in fish,"An investigation of the cytogenetic effects of chromium (Cr(VI) and Cr(III)) in Prussian carp (Carassius auratus gibelio) was made. For detecting cytogenetic damage, micronuclei induction in fish erythrocyte cells was employed. Fish were investigated 100 m above and 400 m below the discharge of leather waste products into the river Ljubljanica, and by exposing fish to three doses of chromium (Cr(VI) and Cr(III)) in the laboratory. The exposure of fish to various concentration levels (sub-lethal) of chromium under laboratory and field conditions caused an increase in the frequency of micronuclei compared with the control groups.","Chromium-induced micronuclei in fish Abs: An investigation of the cytogenetic effects of chromium (Cr(VI) and Cr(III)) in Prussian carp (Carassius auratus gibelio) was made. For detecting cytogenetic damage, micronuclei induction in fish erythrocyte cells was employed. Fish were investigated 100 m above and 400 m below the discharge of leather waste products into the river Ljubljanica, and by exposing fish to three doses of chromium (Cr(VI) and Cr(III)) in the laboratory. The exposure of fish to various concentration levels (sub-lethal) of chromium under laboratory and field conditions caused an increase in the frequency of micronuclei compared with the control groups."
1232212,Marini et al. 1995,Does welding stainless steel cause cancer?,,Does welding stainless steel cause cancer? Abs: 
1232211,Lu and  Yang 1995,Long-term exposure to chromium(VI) oxide leads to defects in sulfate transport system in Chinese hamster ovary cells,"Chromium(VI) resistant Chinese hamster ovary (CHO) cell lines were established in this study by exposing parental CHO-K1 cells to sequential increases in CrO3 concentration. The final concentration of CrO3 used for selection was 7 microM for Cr7 and 16 microM for Cr16 cells. Cr16-1 was a subclone derived from Cr16 cells. Next, these resistant cells were cultured in media without CrO3 for more than 6 months. The resistance of these cells to CrO3 was determined by colony-forming ability following a 24-h treatment. The LD50 of CrO3 for chromium(VI) resistant cells was at least 25-fold higher than that of the parental cells. The cellular growth rate, chromosome number, and the hprt mutation frequency of these chromium(VI) resistant cells were quite similar to their parental cells. The glutathione level, glutathione S-transferase, catalase activity, and metallothionine mRNA level in Cr7 and Cr16-1 cells were not significantly different from their parental cells. Furthermore, Cr16-1 cells were as sensitive as CHO-K1 cells to free-radical generating agents, including hydrogen peroxide, nickel chloride, and methanesulfonate methyl ester, and emetine, i.e., a protein synthesis inhibitor. The uptake of chromium(VI) and the remaining amount of this metal in these resistant and the parental cell lines were assayed by atomic absorption spectrophotometry. Experimental results indicated that a vastly smaller amount of CrO3 entered the resistant cell lines than their parental cells did. A comparison was made of the sulfate uptake abilities of CHO-K1 and chromium(VI) resistant cell lines. These results revealed that the uptake of sulfate anion was substantially reduced in Cr7 and Cr16-1 cells. Extracellular chloride reduced sulfate uptake in CHO-K1 but not in Cr16-1 cells. Therefore, the major causative for chromium(VI) resistance in these resistant cells could possibly be due to the defects in SO4(2-)/C1- transport system for uptake chromium(VI).","Long-term exposure to chromium(VI) oxide leads to defects in sulfate transport system in Chinese hamster ovary cells Abs: Chromium(VI) resistant Chinese hamster ovary (CHO) cell lines were established in this study by exposing parental CHO-K1 cells to sequential increases in CrO3 concentration. The final concentration of CrO3 used for selection was 7 microM for Cr7 and 16 microM for Cr16 cells. Cr16-1 was a subclone derived from Cr16 cells. Next, these resistant cells were cultured in media without CrO3 for more than 6 months. The resistance of these cells to CrO3 was determined by colony-forming ability following a 24-h treatment. The LD50 of CrO3 for chromium(VI) resistant cells was at least 25-fold higher than that of the parental cells. The cellular growth rate, chromosome number, and the hprt mutation frequency of these chromium(VI) resistant cells were quite similar to their parental cells. The glutathione level, glutathione S-transferase, catalase activity, and metallothionine mRNA level in Cr7 and Cr16-1 cells were not significantly different from their parental cells. Furthermore, Cr16-1 cells were as sensitive as CHO-K1 cells to free-radical generating agents, including hydrogen peroxide, nickel chloride, and methanesulfonate methyl ester, and emetine, i.e., a protein synthesis inhibitor. The uptake of chromium(VI) and the remaining amount of this metal in these resistant and the parental cell lines were assayed by atomic absorption spectrophotometry. Experimental results indicated that a vastly smaller amount of CrO3 entered the resistant cell lines than their parental cells did. A comparison was made of the sulfate uptake abilities of CHO-K1 and chromium(VI) resistant cell lines. These results revealed that the uptake of sulfate anion was substantially reduced in Cr7 and Cr16-1 cells. Extracellular chloride reduced sulfate uptake in CHO-K1 but not in Cr16-1 cells. Therefore, the major causative for chromium(VI) resistance in these resistant cells could possibly be due to the defects in SO4(2-)/C1- transport system for uptake chromium(VI)."
1232210,Mishra et al. 1995,Studies on uptake of trivalent and hexavalent chromium by maize (Zea mays),"Pot culture experiments were carried out to study the uptake and translocation of chromium from irrigation water when supplied in its trivalent and hexavalent states to maize plants grown in soil and sand culture. The uptake of chromium was observed to increase with increase in the concentration for both oxidation states of chromium. For the root, the observed order of uptake was CrIII sand &gt; CrVI sand &gt; CrIII soil &gt; CrVI soil, whereas in the lower shoot, upper shoot and fruit the order was CrVI sand &gt; CrVI soil &gt; CrIII sand &gt; CrIII soil. Significantly high uptake of chromium by roots in the sand culture (CrIII treatment) is attributed to the effect of root exudates and degradation products on the mobilization of CrIII. In aerial parts of the plants a higher uptake was observed when the initial supply was CrVI. The trends observed are explained on the basis of the redox behaviour of chromium.","Studies on uptake of trivalent and hexavalent chromium by maize (Zea mays) Abs: Pot culture experiments were carried out to study the uptake and translocation of chromium from irrigation water when supplied in its trivalent and hexavalent states to maize plants grown in soil and sand culture. The uptake of chromium was observed to increase with increase in the concentration for both oxidation states of chromium. For the root, the observed order of uptake was CrIII sand &gt; CrVI sand &gt; CrIII soil &gt; CrVI soil, whereas in the lower shoot, upper shoot and fruit the order was CrVI sand &gt; CrVI soil &gt; CrIII sand &gt; CrIII soil. Significantly high uptake of chromium by roots in the sand culture (CrIII treatment) is attributed to the effect of root exudates and degradation products on the mobilization of CrIII. In aerial parts of the plants a higher uptake was observed when the initial supply was CrVI. The trends observed are explained on the basis of the redox behaviour of chromium."
1232209,Capellmann et al. 1995,Influence of reducing compounds on the formation of DNA-protein cross-links in HL-60 cells induced by hexavalent chromium,"The influence of reducing compounds on the formation of DNA--protein cross-links induced by hexavalent chromium was studied in the human cell line HL-60. Analysis of cytoplasmic concentration of ascorbic acid and glutathione by HPLC in these cells showed that ascorbic acid was not detectable (detection limit: 0.1 nmol). The cellular content of glutathione was low (6 nmol/million cells). It could easily be depleted with diethylmaleate. The effect of glutathione, ascorbic acid and ascorbyl palmitate alone, or glutathione in combination with ascorbyl palmitate was investigated. It could be shown that glutathione increased DNA--protein cross-links in HL-60 cells by chromate significantly in a dose dependent manner, while pre-incubation with L-ascorbic acid and L-ascorbic acid-6-hexadecanate (ascorbyl palmitate) did not change the cross-linking activity of chromate significantly. Ascorbyl palmitate counteracted the increasing effect of glutathione on the concentration of DNA--protein cross-links in HL-60 cells after exposure to chromate. As ascorbic acid reacts much faster with hexavalent chromium at physiological pH than glutathione does, this suggests an influence of the reaction velocity of the redox reaction between hexavalent chromium and the reducing compounds on the toxification of Cr(VI) and formation of DNA--protein cross-links.","Influence of reducing compounds on the formation of DNA-protein cross-links in HL-60 cells induced by hexavalent chromium Abs: The influence of reducing compounds on the formation of DNA--protein cross-links induced by hexavalent chromium was studied in the human cell line HL-60. Analysis of cytoplasmic concentration of ascorbic acid and glutathione by HPLC in these cells showed that ascorbic acid was not detectable (detection limit: 0.1 nmol). The cellular content of glutathione was low (6 nmol/million cells). It could easily be depleted with diethylmaleate. The effect of glutathione, ascorbic acid and ascorbyl palmitate alone, or glutathione in combination with ascorbyl palmitate was investigated. It could be shown that glutathione increased DNA--protein cross-links in HL-60 cells by chromate significantly in a dose dependent manner, while pre-incubation with L-ascorbic acid and L-ascorbic acid-6-hexadecanate (ascorbyl palmitate) did not change the cross-linking activity of chromate significantly. Ascorbyl palmitate counteracted the increasing effect of glutathione on the concentration of DNA--protein cross-links in HL-60 cells after exposure to chromate. As ascorbic acid reacts much faster with hexavalent chromium at physiological pH than glutathione does, this suggests an influence of the reaction velocity of the redox reaction between hexavalent chromium and the reducing compounds on the toxification of Cr(VI) and formation of DNA--protein cross-links."
1232208,Chowdhury and  Mitra 1995,Spermatogenic and steroidogenic impairment after chromium treatment in rats,"Feeding of hexavalent chromium at doses of 20, 40 and 60 mg/kg daily for 90 days caused cellular impairment in rat testis. Spermatogenic inhibition coupled with deminution in testicular protein, DNA and RNA was significant at the doses 40 and 60 mg kg chromium. Decline of Leydig cell population and nuclear diameter indicated the steroidogenic impairment and the effect was confirmed by the significant inhibition of 3 beta-delta 5-hydroxy steroid dehydrogenase along with low level of serum testosterone.","Spermatogenic and steroidogenic impairment after chromium treatment in rats Abs: Feeding of hexavalent chromium at doses of 20, 40 and 60 mg/kg daily for 90 days caused cellular impairment in rat testis. Spermatogenic inhibition coupled with deminution in testicular protein, DNA and RNA was significant at the doses 40 and 60 mg kg chromium. Decline of Leydig cell population and nuclear diameter indicated the steroidogenic impairment and the effect was confirmed by the significant inhibition of 3 beta-delta 5-hydroxy steroid dehydrogenase along with low level of serum testosterone."
1232207,Hjollund et al. 1995,Male-mediated risk of spontaneous abortion with reference to stainless steel welding,"<strong>OBJECTIVES: </strong>It was hypothesized that the welding of stainless steel involves a risk of male-mediated developmental toxicity because of exposure to mutagenic substances, including hexavalent chromium. The purpose of the present study was to corroborate or refute earlier findings that spouses of stainless steel welders have an increased risk of spontaneous abortion.<br /><br /><strong>METHODS: </strong>The occurrence of spontaneous abortion among 2520 pregnancies of spouses of 1715 married metal workers from 1977 through 1987 was examined. Occupational histories were collected with a postal questionnaire in a previous study. Information on children born live, spontaneous abortion, and induced abortion was obtained from national medical registers.<br /><br /><strong>RESULTS: </strong>The proportion of spontaneous abortions was not increased for pregnancies at risk from stainless steel welding when compared with pregnancies not at risk (odds ratio 0.78, 95% confidence interval 0.55-1.1). The risk estimate was robust to adjustment for potential confounding effects of maternal age and parity and male smoking and alcohol consumption.<br /><br /><strong>CONCLUSIONS: </strong>This study does not corroborate earlier findings that spouses of stainless steel welders have increased risk of spontaneous abortion. A reanalysis indicated that earlier findings were probably biased because the job exposure of male metal workers is apparently modified by the outcome of their partners' first pregnancy.","Male-mediated risk of spontaneous abortion with reference to stainless steel welding Abs: <strong>OBJECTIVES: </strong>It was hypothesized that the welding of stainless steel involves a risk of male-mediated developmental toxicity because of exposure to mutagenic substances, including hexavalent chromium. The purpose of the present study was to corroborate or refute earlier findings that spouses of stainless steel welders have an increased risk of spontaneous abortion.<br /><br /><strong>METHODS: </strong>The occurrence of spontaneous abortion among 2520 pregnancies of spouses of 1715 married metal workers from 1977 through 1987 was examined. Occupational histories were collected with a postal questionnaire in a previous study. Information on children born live, spontaneous abortion, and induced abortion was obtained from national medical registers.<br /><br /><strong>RESULTS: </strong>The proportion of spontaneous abortions was not increased for pregnancies at risk from stainless steel welding when compared with pregnancies not at risk (odds ratio 0.78, 95% confidence interval 0.55-1.1). The risk estimate was robust to adjustment for potential confounding effects of maternal age and parity and male smoking and alcohol consumption.<br /><br /><strong>CONCLUSIONS: </strong>This study does not corroborate earlier findings that spouses of stainless steel welders have increased risk of spontaneous abortion. A reanalysis indicated that earlier findings were probably biased because the job exposure of male metal workers is apparently modified by the outcome of their partners' first pregnancy."
1232206,Goh and  Gan 1996,"Change in cement manufacturing process, a cause for decline in chromate allergy?","Hexavalent chromate in cement is the commonest cause of allergic contact dermatitis, especially among construction workers. Over the past decades, there has been a general decline in the prevalence of chromate allergy among construction workers. We suspect that a change in the constituents of cement, resulting in the lowering of hexavalent chromate, contributed to the decline. Slag (free from hexavalent chromate) from the iron-quenched, blast furnace process has been used as a substitute for clinker (which contains high hexavalent chromate) in manufacturing cement. As a result, the slag has diluted the hexavalent chromate content of cement. Our analytical study showed that slag is free from hexavalent chromate and that the hexavalent chromate of clinker ranged from 6-17 micrograms/g. Substituting slag for clinker resulted in dilution of hexavalent chromate in the cement. The hexavalent chromate content of cement declines proportionately with increasing proportion of slag, e.g., a cement containing 5% slag has a total hexavalent chromate concentration of 17.5 micrograms/g, whereas increasing the proportion of slag to 60% reduced the hexavalent chromate content to 7.1 micrograms/gm in the same cement.","Change in cement manufacturing process, a cause for decline in chromate allergy? Abs: Hexavalent chromate in cement is the commonest cause of allergic contact dermatitis, especially among construction workers. Over the past decades, there has been a general decline in the prevalence of chromate allergy among construction workers. We suspect that a change in the constituents of cement, resulting in the lowering of hexavalent chromate, contributed to the decline. Slag (free from hexavalent chromate) from the iron-quenched, blast furnace process has been used as a substitute for clinker (which contains high hexavalent chromate) in manufacturing cement. As a result, the slag has diluted the hexavalent chromate content of cement. Our analytical study showed that slag is free from hexavalent chromate and that the hexavalent chromate of clinker ranged from 6-17 micrograms/g. Substituting slag for clinker resulted in dilution of hexavalent chromate in the cement. The hexavalent chromate content of cement declines proportionately with increasing proportion of slag, e.g., a cement containing 5% slag has a total hexavalent chromate concentration of 17.5 micrograms/g, whereas increasing the proportion of slag to 60% reduced the hexavalent chromate content to 7.1 micrograms/gm in the same cement."
1232205,Lukanova et al. 1996,"Occupational exposure to Cr(VI): comparison between chromium levels in lymphocytes, erythrocytes, and urine","The relationships between chromium (Cr) levels in lymphocytes, erythrocytes, urine, and ambient air were compared among 14 chrome-platers from a metallurgic plant in Bulgaria and two groups of local controls, one from the same heavily polluted industrial town as the chrome-platers (n = 11) and one from a seaside resort town 100 km away (n = 6). Among the chrome-platers, the Cr concentration in peripheral lymphocytes was positively correlated with total Cr and Cr(VI) levels in ambient air and with Cr excretion in urine. As compared to the controls, the chrome-platers had mean Cr levels in lymphocytes twice as high, in erythrocytes ninefold higher, and in urine fourfold to eightfold higher. Although Cr levels in urine and lymphocytes were similar between the two control groups, levels in erythrocytes were 3 times higher among subjects from the industrial area than among those from the seaside town. The study suggests that lymphocyte Cr could be a good indicator of the Cr body burden caused by high exposures to Cr(VI), such as in electroplating operations. In these conditions, erythrocyte Cr may be less useful, possibly owing to increased toxicity due to the high affinity of erythrocytes for Cr. However, when exposure is lower, such as in most environmental situations, erythrocyte Cr should provide a better and more sensitive index than lymphocyte Cr. By contrast, urinary Cr, which provides information on total Cr exposure, including Cr(III) from dietary and environmental sources, does not seem to be of value for studying occupational exposure to Cr(VI).","Occupational exposure to Cr(VI): comparison between chromium levels in lymphocytes, erythrocytes, and urine Abs: The relationships between chromium (Cr) levels in lymphocytes, erythrocytes, urine, and ambient air were compared among 14 chrome-platers from a metallurgic plant in Bulgaria and two groups of local controls, one from the same heavily polluted industrial town as the chrome-platers (n = 11) and one from a seaside resort town 100 km away (n = 6). Among the chrome-platers, the Cr concentration in peripheral lymphocytes was positively correlated with total Cr and Cr(VI) levels in ambient air and with Cr excretion in urine. As compared to the controls, the chrome-platers had mean Cr levels in lymphocytes twice as high, in erythrocytes ninefold higher, and in urine fourfold to eightfold higher. Although Cr levels in urine and lymphocytes were similar between the two control groups, levels in erythrocytes were 3 times higher among subjects from the industrial area than among those from the seaside town. The study suggests that lymphocyte Cr could be a good indicator of the Cr body burden caused by high exposures to Cr(VI), such as in electroplating operations. In these conditions, erythrocyte Cr may be less useful, possibly owing to increased toxicity due to the high affinity of erythrocytes for Cr. However, when exposure is lower, such as in most environmental situations, erythrocyte Cr should provide a better and more sensitive index than lymphocyte Cr. By contrast, urinary Cr, which provides information on total Cr exposure, including Cr(III) from dietary and environmental sources, does not seem to be of value for studying occupational exposure to Cr(VI)."
1232204,Anjum et al. 1996,Effect of hexavalent chromium on drug-metabolizing enzymes in male domesticated rabbits,"We studied the effect of chromium on the drug-metabolizing enzymes (DME) in male New Zealand white rabbits, Oryctolagus cuniculus, with and without pretreatment with phenobarbitone (PB) and promethazine (PM). The activities of cytochrome P-450 (183%), aniline hydroxylase (ANH, 265%), acetanilide hydroxylase (ACH, 160%), benzphetamine demethylase (BD, 112%), aminopyrine demethylase (AD, 97%), N,N,-dimethyl aniline demethylase (DAD, 72%), and cytochrome-c-reductase (100%) were increased after PB treatment. The activities of cytochrome b5 and N,N,-dimethyl aniline N-oxide (DAO) were, however, decreased 79% and 47%, respectively. Most of the DME remained unaffected after PM treatment except for the increase in ANH (55%), ACH (56%), and BD (16%). Potassium dichromate administered to rabbits at a dose of 8 mg/kg body weight/day for 5 days resulted in an increase in the activities of ANH (108%), BD (76%), AD (25%), and DAD (49%), while that of cytochrome b5 and DAO were inhibited 81 and 77%, respectively. There was no effect on the activities of cytochrome P-450, ACH, and cytochrome-c-reductase. Chromium, administered to PB-pretreated animals decreased the activities of ANH (41%), ACH (35%), BD (34%), AD (30%), DAD (51%), cytochrome-c-reductase (72%), and DAO (62%). Other enzymes remained unaffected. When administered to PM-pretreated animals, the activities of ANH, BD, AD, and DAD increased 34, 69, 24 and 54%, respectively, whereas activities of cytochrome b5 and DAO were decreased 96 and 68%, respectively. All other DME remained unaffected.","Effect of hexavalent chromium on drug-metabolizing enzymes in male domesticated rabbits Abs: We studied the effect of chromium on the drug-metabolizing enzymes (DME) in male New Zealand white rabbits, Oryctolagus cuniculus, with and without pretreatment with phenobarbitone (PB) and promethazine (PM). The activities of cytochrome P-450 (183%), aniline hydroxylase (ANH, 265%), acetanilide hydroxylase (ACH, 160%), benzphetamine demethylase (BD, 112%), aminopyrine demethylase (AD, 97%), N,N,-dimethyl aniline demethylase (DAD, 72%), and cytochrome-c-reductase (100%) were increased after PB treatment. The activities of cytochrome b5 and N,N,-dimethyl aniline N-oxide (DAO) were, however, decreased 79% and 47%, respectively. Most of the DME remained unaffected after PM treatment except for the increase in ANH (55%), ACH (56%), and BD (16%). Potassium dichromate administered to rabbits at a dose of 8 mg/kg body weight/day for 5 days resulted in an increase in the activities of ANH (108%), BD (76%), AD (25%), and DAD (49%), while that of cytochrome b5 and DAO were inhibited 81 and 77%, respectively. There was no effect on the activities of cytochrome P-450, ACH, and cytochrome-c-reductase. Chromium, administered to PB-pretreated animals decreased the activities of ANH (41%), ACH (35%), BD (34%), AD (30%), DAD (51%), cytochrome-c-reductase (72%), and DAO (62%). Other enzymes remained unaffected. When administered to PM-pretreated animals, the activities of ANH, BD, AD, and DAD increased 34, 69, 24 and 54%, respectively, whereas activities of cytochrome b5 and DAO were decreased 96 and 68%, respectively. All other DME remained unaffected."
1232203,Kortenkamp et al. 1996,A role for molecular oxygen in the formation of DNA damage during the reduction of the carcinogen chromium (VI) by glutathione,"Although well-established as carcinogens, the way in which chromium (VI) compounds exert their carcinogenic, mutagenic, and DNA-damaging potential remains obscure. It is clear that inside cells chromium(VI) is activated to its ultimate carcinogenic form by reducing agents including glutathione (GSH). The present study is intended to clarify if Fenton mechanisms are likely to be important in the formation of DNA lesions by chromium(VI) in combination with GSH. In buffer solutions which were treated to remove Fenton-active metal ions as well as in those not further purified, chromate and GSH induced similar numbers of single-strand breaks (SSB) in isolated PM2 DNA. Molecular oxygen was found to be essential for the formation of SSB, but chromium(V) species arising from chromate/GSH, unless activated by oxygen, appeared to be unreactive toward DNA. Upon addition of Mn(II) to solutions of chromium(VI) and GSH a diminution of Mn(II) ESR signals was observed, good evidence for the presence of chromium(IV) species. Using gas chromatography/mass spectrometry in selective ion-monitoring mode and high-performance liquid chromatography with electrochemical detection, we were able to show that Cr(VI)/GSH failed to induce base modifications typical of hydroxyl radical attack on DNA. Experimental conditions which readily induced SSB gave rise to the formation of chromium-DNA adducts, clearly demonstrating that the generation of these two DNA lesions is not mutually exclusive. We conclude that models which ascribe the induction of chromium-DNA adducts to chromium(V) and the generation of oxidative DNA damage including SSB to hydrogen peroxide are oversimplistic. It is not necessary to invoke a mechanism requiring the presence of added hydrogen peroxide to account for the ability of Cr(VI)/GSH to cause SSB. Our findings suggest that the combination of GSH, molecular oxygen, and chromium(VI) can damage DNA via non-Fenton pathways.","A role for molecular oxygen in the formation of DNA damage during the reduction of the carcinogen chromium (VI) by glutathione Abs: Although well-established as carcinogens, the way in which chromium (VI) compounds exert their carcinogenic, mutagenic, and DNA-damaging potential remains obscure. It is clear that inside cells chromium(VI) is activated to its ultimate carcinogenic form by reducing agents including glutathione (GSH). The present study is intended to clarify if Fenton mechanisms are likely to be important in the formation of DNA lesions by chromium(VI) in combination with GSH. In buffer solutions which were treated to remove Fenton-active metal ions as well as in those not further purified, chromate and GSH induced similar numbers of single-strand breaks (SSB) in isolated PM2 DNA. Molecular oxygen was found to be essential for the formation of SSB, but chromium(V) species arising from chromate/GSH, unless activated by oxygen, appeared to be unreactive toward DNA. Upon addition of Mn(II) to solutions of chromium(VI) and GSH a diminution of Mn(II) ESR signals was observed, good evidence for the presence of chromium(IV) species. Using gas chromatography/mass spectrometry in selective ion-monitoring mode and high-performance liquid chromatography with electrochemical detection, we were able to show that Cr(VI)/GSH failed to induce base modifications typical of hydroxyl radical attack on DNA. Experimental conditions which readily induced SSB gave rise to the formation of chromium-DNA adducts, clearly demonstrating that the generation of these two DNA lesions is not mutually exclusive. We conclude that models which ascribe the induction of chromium-DNA adducts to chromium(V) and the generation of oxidative DNA damage including SSB to hydrogen peroxide are oversimplistic. It is not necessary to invoke a mechanism requiring the presence of added hydrogen peroxide to account for the ability of Cr(VI)/GSH to cause SSB. Our findings suggest that the combination of GSH, molecular oxygen, and chromium(VI) can damage DNA via non-Fenton pathways."
1232202,Xu et al. 1996,"Chromium(VI) treatment of normal human lung cells results in guanine-specific DNA polymerase arrest, DNA-DNA cross-links and S-phase blockade of cell cycle","Previous studies have shown that in vitro treatment of a synthetic double-stranded DNA template with chromium(III), or chromium(VI) in the presence of ascorbate, resulted in guanine-specific DNA polymerase arrests that correlated strongly with DNA-DNA cross-linking. In vivo chromium(VI) undergoes a more complicated intracellular cascade of reductive metabolism than is achievable in an in vitro model. Moreover, in living cells, DNA is highly packaged in the form of chromatin which may alter the accessibility of DNA to chromium. A repetitive primer-extension assay was employed to determine whether chromium forms polymerase-arresting lesions in vivo. Normal human lung fibroblasts treated with chromium(VI) exhibited adduct levels of 0.13-0.92 mmol Cr/mol DNA-nucleotides in the total genome (0.26-1.84 Cr adducts/Kbp DNA) and DNA interstrand cross-links. Genomic DNA was isolated and alphoid sequences (1-5% of the genome) were used as a substrate for repetitive primer extension using Taq polymerase. The results showed a dose-dependent, guanine-specific, replication termination, even at low doses resulting in greater than 90% survival. The same treatment resulted in dose-dependent suppression of thymidine incorporation into DNA immediately after treatment. Thymidine incorporation increased during the first 6 h after the 2-h exposure, probably related to the repair of the single strand breaks, but then returned to high suppression levels at 24 h. The chromate treatments inhibited cell growth by specific blocking of the progression of cells through S-phase of the cell cycle. The results confirmed our studies in cell-free systems and taken together they strongly indicate that guanine-guanine DNA interstrand cross-links induced by chromate in living cells is the lesion responsible for blocking DNA replication processivity.","Chromium(VI) treatment of normal human lung cells results in guanine-specific DNA polymerase arrest, DNA-DNA cross-links and S-phase blockade of cell cycle Abs: Previous studies have shown that in vitro treatment of a synthetic double-stranded DNA template with chromium(III), or chromium(VI) in the presence of ascorbate, resulted in guanine-specific DNA polymerase arrests that correlated strongly with DNA-DNA cross-linking. In vivo chromium(VI) undergoes a more complicated intracellular cascade of reductive metabolism than is achievable in an in vitro model. Moreover, in living cells, DNA is highly packaged in the form of chromatin which may alter the accessibility of DNA to chromium. A repetitive primer-extension assay was employed to determine whether chromium forms polymerase-arresting lesions in vivo. Normal human lung fibroblasts treated with chromium(VI) exhibited adduct levels of 0.13-0.92 mmol Cr/mol DNA-nucleotides in the total genome (0.26-1.84 Cr adducts/Kbp DNA) and DNA interstrand cross-links. Genomic DNA was isolated and alphoid sequences (1-5% of the genome) were used as a substrate for repetitive primer extension using Taq polymerase. The results showed a dose-dependent, guanine-specific, replication termination, even at low doses resulting in greater than 90% survival. The same treatment resulted in dose-dependent suppression of thymidine incorporation into DNA immediately after treatment. Thymidine incorporation increased during the first 6 h after the 2-h exposure, probably related to the repair of the single strand breaks, but then returned to high suppression levels at 24 h. The chromate treatments inhibited cell growth by specific blocking of the progression of cells through S-phase of the cell cycle. The results confirmed our studies in cell-free systems and taken together they strongly indicate that guanine-guanine DNA interstrand cross-links induced by chromate in living cells is the lesion responsible for blocking DNA replication processivity."
1232201,Tisch and  Maier 1996,[Squamous epithelial carcinoma of the tongue after occupational exposure to chromium VI compounds],"<strong>BACKGROUND: </strong>The major key risk factors of head and neck cancer are chronic alcohol and tobacco consumption. There ist further increasing evidence that exposure to hazardous occupational agents increases the cancer risk substantially.<br /><br /><strong>CASE REPORT: </strong>By means of a case report and an overview of the literature, the role of occupational exposure to hexavalent chromium compounds as a risk factor of head and neck cancer is analysed.<br /><br /><strong>RESULTS AND CONCLUSIONS: </strong>The mechanisms of chromium carcinogenesis are outlined. Possible interactions of life-style factors and occupational factors which may influence the cancer risk in a synergistic manner are also discussed. Critical analysis of the literature provides evidence of a possible role of occupational exposition to hexavalent chromium compounds as a risk factor for oral squamous cell cancer.","[Squamous epithelial carcinoma of the tongue after occupational exposure to chromium VI compounds] Abs: <strong>BACKGROUND: </strong>The major key risk factors of head and neck cancer are chronic alcohol and tobacco consumption. There ist further increasing evidence that exposure to hazardous occupational agents increases the cancer risk substantially.<br /><br /><strong>CASE REPORT: </strong>By means of a case report and an overview of the literature, the role of occupational exposure to hexavalent chromium compounds as a risk factor of head and neck cancer is analysed.<br /><br /><strong>RESULTS AND CONCLUSIONS: </strong>The mechanisms of chromium carcinogenesis are outlined. Possible interactions of life-style factors and occupational factors which may influence the cancer risk in a synergistic manner are also discussed. Critical analysis of the literature provides evidence of a possible role of occupational exposition to hexavalent chromium compounds as a risk factor for oral squamous cell cancer."
1232200,Edgehill 1996,Influence of chromium (VI) and acidic conditions on removal of pentachlorophenol from soil by Arthrobacter strain ATCC 33790,,Influence of chromium (VI) and acidic conditions on removal of pentachlorophenol from soil by Arthrobacter strain ATCC 33790 Abs: 
1232199,Nair et al. 1996,Mixture risk assessment: a case study of Monsanto experiences,"Monsanto employs several pragmatic approaches for evaluating the toxicity of mixtures. These approaches are similar to those recommended by many national and international agencies. When conducting hazard and risk assessments, priority is always given to using data collected directly on the mixture of concern. To provide an example of the first tier of evaluation, actual data on acute respiratory irritation studies on mixtures were evaluated to determine whether the principle of additivity was applicable to the mixture evaluated. If actual data on the mixture are unavailable, extrapolation across similar mixtures is considered. Because many formulations are quite similar in composition, the toxicity data from one mixture can be extended to a closely related mixture in a scientifically justifiable manner. An example of a family of products where such extrapolations have been made is presented to exemplify this second approach. Lastly, if data on similar mixtures are unavailable, data on component fractions are used to predict the toxicity of the mixture. In this third approach, process knowledge and scientific judgement are used to determine how the known toxicological properties of the individual fractions affect toxicity of the mixture. Three examples of plant effluents where toxicological data on fractions were used to predict the toxicity of the mixture are discussed. The results of the analysis are used to discuss the predictive value of each of the above mentioned toxicological approaches for evaluating chemical mixtures.","Mixture risk assessment: a case study of Monsanto experiences Abs: Monsanto employs several pragmatic approaches for evaluating the toxicity of mixtures. These approaches are similar to those recommended by many national and international agencies. When conducting hazard and risk assessments, priority is always given to using data collected directly on the mixture of concern. To provide an example of the first tier of evaluation, actual data on acute respiratory irritation studies on mixtures were evaluated to determine whether the principle of additivity was applicable to the mixture evaluated. If actual data on the mixture are unavailable, extrapolation across similar mixtures is considered. Because many formulations are quite similar in composition, the toxicity data from one mixture can be extended to a closely related mixture in a scientifically justifiable manner. An example of a family of products where such extrapolations have been made is presented to exemplify this second approach. Lastly, if data on similar mixtures are unavailable, data on component fractions are used to predict the toxicity of the mixture. In this third approach, process knowledge and scientific judgement are used to determine how the known toxicological properties of the individual fractions affect toxicity of the mixture. Three examples of plant effluents where toxicological data on fractions were used to predict the toxicity of the mixture are discussed. The results of the analysis are used to discuss the predictive value of each of the above mentioned toxicological approaches for evaluating chemical mixtures."
1232195,Anjum and  Shakoori 1997,Sublethal effects of hexavalent chromium on the body growth rate and liver function enzymes of phenobarbitone-pretreated and promethazine-pretreated rabbits,"Hepatotoxic effects of chromium have been studied on the liver function enzymes of male New Zealand white rabbits, Oryctolagus cuniculus, with and without pretreatment with phenobarbitone (PB) and promethazine (PM). The total body weight was decreased under all experimental conditions. After PB administration (5 mg/kg body wt/day for 5 days), the serum glutamate oxaloacetate transaminase (GOT), glutamate pyruvate transaminase (GPT), lactate dehydrogenase (LDH), and isocitrate dehydrogenase (ICDH) activities decreased 21%, 65%, 25%, and 37%, respectively, whereas the alkaline phosphatase (AP) activity increased 70%. After PM treatment (5 mg/kg body wt/day for 5 days) the serum GPT was inhibited 73%, whereas LDH activity was increased 37%. The hepatic GPT and AP activities decreased after PB (52% and 31%, respectively), and PM (48% and 44%, respectively) treatments, whereas the activities of LDH and ICDH increased (after PB: 817% and 109%, respectively, and after PM: 136% and 44%, respectively). Potassium dichromate, administered at a dose of 8 mg/kg body wt/day for 5 days, decreased serum GOT (44%), GPT (61%), LDH (63%), and AP (44%) activities. The hepatic GOT, GPT and AP activities were likewise decreased (86%, 51%, and 46%, respectively), whereas hepatic LDH and ICDH activities increased 667% and 193%, respectively. When administered to PB-pretreated animals, the serum GOT and AP activities were decreased (50% and 68%), whereas ICDH was increased (29%). The hepatic GOT, LDH, and ICDH activities increased 79%, 221%, and 130%, respectively. In the PM-pretreated animals, the chromium treatment inhibited the activities of serum GOT (48%), GPT (44%), and LDH (43%). The hepatic GPT, LDH, and ICDH activities increased 90%, 133%, and 52%, respectively.","Sublethal effects of hexavalent chromium on the body growth rate and liver function enzymes of phenobarbitone-pretreated and promethazine-pretreated rabbits Abs: Hepatotoxic effects of chromium have been studied on the liver function enzymes of male New Zealand white rabbits, Oryctolagus cuniculus, with and without pretreatment with phenobarbitone (PB) and promethazine (PM). The total body weight was decreased under all experimental conditions. After PB administration (5 mg/kg body wt/day for 5 days), the serum glutamate oxaloacetate transaminase (GOT), glutamate pyruvate transaminase (GPT), lactate dehydrogenase (LDH), and isocitrate dehydrogenase (ICDH) activities decreased 21%, 65%, 25%, and 37%, respectively, whereas the alkaline phosphatase (AP) activity increased 70%. After PM treatment (5 mg/kg body wt/day for 5 days) the serum GPT was inhibited 73%, whereas LDH activity was increased 37%. The hepatic GPT and AP activities decreased after PB (52% and 31%, respectively), and PM (48% and 44%, respectively) treatments, whereas the activities of LDH and ICDH increased (after PB: 817% and 109%, respectively, and after PM: 136% and 44%, respectively). Potassium dichromate, administered at a dose of 8 mg/kg body wt/day for 5 days, decreased serum GOT (44%), GPT (61%), LDH (63%), and AP (44%) activities. The hepatic GOT, GPT and AP activities were likewise decreased (86%, 51%, and 46%, respectively), whereas hepatic LDH and ICDH activities increased 667% and 193%, respectively. When administered to PB-pretreated animals, the serum GOT and AP activities were decreased (50% and 68%), whereas ICDH was increased (29%). The hepatic GOT, LDH, and ICDH activities increased 79%, 221%, and 130%, respectively. In the PM-pretreated animals, the chromium treatment inhibited the activities of serum GOT (48%), GPT (44%), and LDH (43%). The hepatic GPT, LDH, and ICDH activities increased 90%, 133%, and 52%, respectively."
1232194,Chen et al. 1997,"One-electron reduction of chromium(VI) by alpha-lipoic acid and related hydroxyl radical generation, dG hydroxylation and nuclear transcription factor-kappaB activation","Reaction of chromium(VI) with alpha-lipoic acid (reduced form, also called 1,2-dithiolane-3-pentanoic acid) generated Cr(V) and hydroxyl radical (*OH) as measured by electron spin resonance and ESR spin trapping. 5,5-Dimethyl-1-pyrroline was used as a spin trapping agent. Catalase inhibited the *OH generation and enhanced the Cr(V) formation. Superoxide dismutase had an opposite effect. H2O2 enhanced the *OH generation and decreased the Cr(V) formation in a dose-dependent manner. Metal chelators, EDTA, diethylenetriaminepentaacetic acid, deferoxamine, and 1, 10-phenanthroline inhibited *OH radical generation in the order of EDTA &gt; 1,10-phenanthroline &gt; DTPA &gt; deferoxamine. Oxygen consumption measurements indicated that molecular oxygen was used to generate *OH radical in the mixture of Cr(VI) and alpha-lipoic acid. H2O2 and superoxide radical (O2-) were involved as reactive intermediates. The *OH radical was generated via Cr(V)-mediated Fenton-like reaction (Cr(V) + H2O2 --&gt; Cr(VI) + OH- + *OH). HPLC measurements show that the *OH radical generated by this reaction is capable of generating 8-hydroxyl-2'-deoxyguanosine from 2-deoxyguanosine. Incubation of Cr(VI) with cultured Jurkat cells resulted in an activation of DNA binding activity of the nuclear factor (NF)-kappaB. Addition of alpha-lipoic acid enhanced the NF-kappaB activation, while the *OH radical scavenger, sodium formate, inhibited it, showing that alpha-lipoic acid enhanced Cr(VI)-induced NF-kappaB activation via free radical reactions. The results indicate that while alpha-lipoic acid is considered to be an antioxidant, it may be a cellular one-electron Cr(VI) reductant and could be involved in the mechanism of Cr(VI)-induced carcinogenesis.","One-electron reduction of chromium(VI) by alpha-lipoic acid and related hydroxyl radical generation, dG hydroxylation and nuclear transcription factor-kappaB activation Abs: Reaction of chromium(VI) with alpha-lipoic acid (reduced form, also called 1,2-dithiolane-3-pentanoic acid) generated Cr(V) and hydroxyl radical (*OH) as measured by electron spin resonance and ESR spin trapping. 5,5-Dimethyl-1-pyrroline was used as a spin trapping agent. Catalase inhibited the *OH generation and enhanced the Cr(V) formation. Superoxide dismutase had an opposite effect. H2O2 enhanced the *OH generation and decreased the Cr(V) formation in a dose-dependent manner. Metal chelators, EDTA, diethylenetriaminepentaacetic acid, deferoxamine, and 1, 10-phenanthroline inhibited *OH radical generation in the order of EDTA &gt; 1,10-phenanthroline &gt; DTPA &gt; deferoxamine. Oxygen consumption measurements indicated that molecular oxygen was used to generate *OH radical in the mixture of Cr(VI) and alpha-lipoic acid. H2O2 and superoxide radical (O2-) were involved as reactive intermediates. The *OH radical was generated via Cr(V)-mediated Fenton-like reaction (Cr(V) + H2O2 --&gt; Cr(VI) + OH- + *OH). HPLC measurements show that the *OH radical generated by this reaction is capable of generating 8-hydroxyl-2'-deoxyguanosine from 2-deoxyguanosine. Incubation of Cr(VI) with cultured Jurkat cells resulted in an activation of DNA binding activity of the nuclear factor (NF)-kappaB. Addition of alpha-lipoic acid enhanced the NF-kappaB activation, while the *OH radical scavenger, sodium formate, inhibited it, showing that alpha-lipoic acid enhanced Cr(VI)-induced NF-kappaB activation via free radical reactions. The results indicate that while alpha-lipoic acid is considered to be an antioxidant, it may be a cellular one-electron Cr(VI) reductant and could be involved in the mechanism of Cr(VI)-induced carcinogenesis."
1232193,Rafnsson et al. 1997,Risk of lung cancer among masons in Iceland,"<strong>OBJECTIVES: </strong>To estimate the risk of gastrointestinal cancer and lung cancer in a cohort of masons exposed to cement and hexavalent chromium by a follow up in the Icelandic Cancer Registry.<br /><br /><strong>METHODS: </strong>The cohort, 1172 men, was defined as those who had served their apprenticeship and were fully licensed as masons (cement finishers) in Iceland, were born after 1880 and were alive in 1955. The men were exposed to an aerosol of wet concrete, particularly when spraying. According to the analyses of urinary chromium the masons were exposed to hexavalent chromium. A computer file on masons was record linked to the Cancer Registry by making use of the personal identification numbers. Expected cancer incidence was calculated on the basis of number of person-years for each five-year age category during the individual calendar years of the study period and multiplied by the specific incidence for cause and calendar year for men in Iceland provided by the Cancer Registry.<br /><br /><strong>RESULTS: </strong>The standardised incidence ratio (SIR) for all cancers was 1.13 in the total cohort and 1.33 when allowance was made for 30 years to elapse before starting to count person years of risk. The risk for gastrointestinal cancers was not increased. The SIR for lung cancer was 1.69 in the total cohort and 1.77 when a lag of 30 years was included. The SIR for lung cancer among those born in 1920 or later was 1.86. Results from a postal questionnaire showed that fewer masons had never smoked and more masons had stopped smoking than the controls from the general population.<br /><br /><strong>CONCLUSION: </strong>The increased risk of lung cancer among the masons may be related to their work. The exposure information, although limited, supports the suggestion that hexavalent chromium in the cement may be the causal link, as information on the smoking habits indicate that the control for this important possible confounder is adequate.","Risk of lung cancer among masons in Iceland Abs: <strong>OBJECTIVES: </strong>To estimate the risk of gastrointestinal cancer and lung cancer in a cohort of masons exposed to cement and hexavalent chromium by a follow up in the Icelandic Cancer Registry.<br /><br /><strong>METHODS: </strong>The cohort, 1172 men, was defined as those who had served their apprenticeship and were fully licensed as masons (cement finishers) in Iceland, were born after 1880 and were alive in 1955. The men were exposed to an aerosol of wet concrete, particularly when spraying. According to the analyses of urinary chromium the masons were exposed to hexavalent chromium. A computer file on masons was record linked to the Cancer Registry by making use of the personal identification numbers. Expected cancer incidence was calculated on the basis of number of person-years for each five-year age category during the individual calendar years of the study period and multiplied by the specific incidence for cause and calendar year for men in Iceland provided by the Cancer Registry.<br /><br /><strong>RESULTS: </strong>The standardised incidence ratio (SIR) for all cancers was 1.13 in the total cohort and 1.33 when allowance was made for 30 years to elapse before starting to count person years of risk. The risk for gastrointestinal cancers was not increased. The SIR for lung cancer was 1.69 in the total cohort and 1.77 when a lag of 30 years was included. The SIR for lung cancer among those born in 1920 or later was 1.86. Results from a postal questionnaire showed that fewer masons had never smoked and more masons had stopped smoking than the controls from the general population.<br /><br /><strong>CONCLUSION: </strong>The increased risk of lung cancer among the masons may be related to their work. The exposure information, although limited, supports the suggestion that hexavalent chromium in the cement may be the causal link, as information on the smoking habits indicate that the control for this important possible confounder is adequate."
1232192,Zhang and  Li 1997,Cancer mortality in a Chinese population exposed to hexavalent chromium in water,"This report is a clarification and further analysis of our previously published mortality study regarding groundwater contamination with hexavalent chromium (Cr+6) in the JinZhou area of China between 1965 and 1978. In our previous report, we stated that a significant excess of overall cancer mortality was observed (P = 0.04) in five Cr(+6)-contaminated villages combined. Further analysis revealed no clear statistical increase in cancer mortality in the three villages adjacent to the source of the contamination (P = 0.25), where 57% of the wells exceeded the European Community safe drinking water standard of 0.05 ppm Cr+6. These results do not indicate an association of cancer mortality with exposure to Cr(+6)-contaminated groundwater, but might reflect the influence of lifestyle or environmental factors not related to Cr+6. Further follow-up of this cohort is recommended.","Cancer mortality in a Chinese population exposed to hexavalent chromium in water Abs: This report is a clarification and further analysis of our previously published mortality study regarding groundwater contamination with hexavalent chromium (Cr+6) in the JinZhou area of China between 1965 and 1978. In our previous report, we stated that a significant excess of overall cancer mortality was observed (P = 0.04) in five Cr(+6)-contaminated villages combined. Further analysis revealed no clear statistical increase in cancer mortality in the three villages adjacent to the source of the contamination (P = 0.25), where 57% of the wells exceeded the European Community safe drinking water standard of 0.05 ppm Cr+6. These results do not indicate an association of cancer mortality with exposure to Cr(+6)-contaminated groundwater, but might reflect the influence of lifestyle or environmental factors not related to Cr+6. Further follow-up of this cohort is recommended."
1232190,Liu et al. 1997,"Synthesis of Cr(IV)-GSH, its identification and its free hydroxyl radical generation: a model compound for Cr(VI) carcinogenicity","Current models of Cr(VI) carcinogenesis suggest an important role for Cr(IV) as an intermediate, toxic, carcinogenic species, but direct chemical evidence has been lacking. This is because Cr(IV) is a highly reactive oxidation state of Cr and few Cr(IV)-based compounds are known that can be used as a model compound containing a biological ligand. This study reports the isolation of such a stable Cr(IV) complex. The Cr(IV)-GSH complex has been synthesized through the reaction of Cr(VI) with GSH. Its electron paramagnetic resonance (EPR) spectrum exhibits g = 1.9629 and a peak-to-peak line width of 480 G in aqueous medium as well as in the powder form. Magnetic susceptibility measurements showed that the compound has a magnetic moment of 2.53 Bohr magneton per Cr, establishing that the Cr ion has two unpaired electrons, hence its identity as Cr(IV). The Cr(IV)-GSH complex is able to generate hydroxyl (.OH) radical in the presence of molecular oxygen in aqueous medium. Catalase inhibited the .OH radical generation while H2O2 enhanced it, indicating that the .OH radical was generated via a Fenton-like reaction, H2O2 being generated as an intermediate in the reduction of molecular oxygen. Metal ion chelators, deferoxamine and 1,10-phenanthroline, attenuated the generation of Cr(IV)-mediated .OH radical. In the case of deferoxamine, a deferoxamine-derived free radical was generated as shown by EPR measurements. The results imply that Cr(IV) may play an important role in the mechanism of Cr(VI)-induced carcinogenesis and Cr(IV)-GSH can be used as a model compound to study the role of Cr(IV) in this mechanism.","Synthesis of Cr(IV)-GSH, its identification and its free hydroxyl radical generation: a model compound for Cr(VI) carcinogenicity Abs: Current models of Cr(VI) carcinogenesis suggest an important role for Cr(IV) as an intermediate, toxic, carcinogenic species, but direct chemical evidence has been lacking. This is because Cr(IV) is a highly reactive oxidation state of Cr and few Cr(IV)-based compounds are known that can be used as a model compound containing a biological ligand. This study reports the isolation of such a stable Cr(IV) complex. The Cr(IV)-GSH complex has been synthesized through the reaction of Cr(VI) with GSH. Its electron paramagnetic resonance (EPR) spectrum exhibits g = 1.9629 and a peak-to-peak line width of 480 G in aqueous medium as well as in the powder form. Magnetic susceptibility measurements showed that the compound has a magnetic moment of 2.53 Bohr magneton per Cr, establishing that the Cr ion has two unpaired electrons, hence its identity as Cr(IV). The Cr(IV)-GSH complex is able to generate hydroxyl (.OH) radical in the presence of molecular oxygen in aqueous medium. Catalase inhibited the .OH radical generation while H2O2 enhanced it, indicating that the .OH radical was generated via a Fenton-like reaction, H2O2 being generated as an intermediate in the reduction of molecular oxygen. Metal ion chelators, deferoxamine and 1,10-phenanthroline, attenuated the generation of Cr(IV)-mediated .OH radical. In the case of deferoxamine, a deferoxamine-derived free radical was generated as shown by EPR measurements. The results imply that Cr(IV) may play an important role in the mechanism of Cr(VI)-induced carcinogenesis and Cr(IV)-GSH can be used as a model compound to study the role of Cr(IV) in this mechanism."
1232189,Buhl 1997,"Relative sensitivity of three endangered fishes, Colorado squawfish, bonytail, and razorback sucker, to selected metal pollutants","The acute toxicity of four metal pollutants to larval and juvenile stages of endangered Colorado squawfish (Ptychocheilus lucius), bonytail (Gila elegans), and razorback sucker (Xyrauchen texanus) were determined in a water quality representative of that in the Green River, Utah. The rank order of toxicity (96-hr LC50) of the metals to all species and life stages from most toxic to least toxic was mercury (57-168 micrograms/liter) &gt; cadmium (78-168 micrograms/liter) &gt; hexavalent chromium (32,000-123,000 micrograms/liter) &gt; lead (&gt; 170,000 micrograms/liter). In tests with lead, a precipitate formed in all test solutions and no mortalities occurred in these treatments. The larvae of each species were as sensitive or more sensitive than the juveniles to cadmium, hexavalent chromium, and mercury. Overall, the three species exhibited similar sensitivities to cadmium, hexavalent chromium, and mercury. Comparison of test results for the juveniles with toxicity values reported for other freshwater fishes tested in different water qualities indicates that the endangered fishes are more sensitive to cadmium than other cyprinids and centrarchids and less sensitive than salmonids, whereas their sensitivity to hexavalent chromium and mercury is similar to that of other cyprinids, centrarchids, and salmonids.","Relative sensitivity of three endangered fishes, Colorado squawfish, bonytail, and razorback sucker, to selected metal pollutants Abs: The acute toxicity of four metal pollutants to larval and juvenile stages of endangered Colorado squawfish (Ptychocheilus lucius), bonytail (Gila elegans), and razorback sucker (Xyrauchen texanus) were determined in a water quality representative of that in the Green River, Utah. The rank order of toxicity (96-hr LC50) of the metals to all species and life stages from most toxic to least toxic was mercury (57-168 micrograms/liter) &gt; cadmium (78-168 micrograms/liter) &gt; hexavalent chromium (32,000-123,000 micrograms/liter) &gt; lead (&gt; 170,000 micrograms/liter). In tests with lead, a precipitate formed in all test solutions and no mortalities occurred in these treatments. The larvae of each species were as sensitive or more sensitive than the juveniles to cadmium, hexavalent chromium, and mercury. Overall, the three species exhibited similar sensitivities to cadmium, hexavalent chromium, and mercury. Comparison of test results for the juveniles with toxicity values reported for other freshwater fishes tested in different water qualities indicates that the endangered fishes are more sensitive to cadmium than other cyprinids and centrarchids and less sensitive than salmonids, whereas their sensitivity to hexavalent chromium and mercury is similar to that of other cyprinids, centrarchids, and salmonids."
1232188,Costa 1997,Toxicity and carcinogenicity of Cr(VI) in animal models and humans,"The toxicity and carcinogenicity of hexavalent chromium (Cr) in animal and human models are reviewed. The focus of this review is not on the well-established fact that hexavalent Cr compounds of low and high water solubility can induce respiratory cancers, but rather this review addresses other types of cancers induced by exposure to hexavalent Cr compounds. Additionally, non-cancer endpoints are also discussed with documentation of human and animal studies showing non-cancer health effects of hexavalent Cr exposure on the respiratory system, GI system, immune system, liver, and kidney. There is an emerging understanding that because hexavalent chromate is isostructural with phosphate and sulfate, it is readily taken up by the G.I. tract and penetrates to many tissues and organs throughout the body. This is supported by animal studies and experiments using human volunteers. From the epidemiological studies, there is suggestive evidence that hexavalent Cr causes increased risk of bone, prostate, lymphomas, Hodgkins, leukemia, stomach, genital, renal, and bladder cancer, reflecting the ability of hexavalent chromate to penetrate all tissues in the body. A high accumulation of Cr(III) in all tissues and organs is a strong indication of the wide toxic potential of exposure to soluble hexavalent Cr in the drinking water and in the ambient environment.","Toxicity and carcinogenicity of Cr(VI) in animal models and humans Abs: The toxicity and carcinogenicity of hexavalent chromium (Cr) in animal and human models are reviewed. The focus of this review is not on the well-established fact that hexavalent Cr compounds of low and high water solubility can induce respiratory cancers, but rather this review addresses other types of cancers induced by exposure to hexavalent Cr compounds. Additionally, non-cancer endpoints are also discussed with documentation of human and animal studies showing non-cancer health effects of hexavalent Cr exposure on the respiratory system, GI system, immune system, liver, and kidney. There is an emerging understanding that because hexavalent chromate is isostructural with phosphate and sulfate, it is readily taken up by the G.I. tract and penetrates to many tissues and organs throughout the body. This is supported by animal studies and experiments using human volunteers. From the epidemiological studies, there is suggestive evidence that hexavalent Cr causes increased risk of bone, prostate, lymphomas, Hodgkins, leukemia, stomach, genital, renal, and bladder cancer, reflecting the ability of hexavalent chromate to penetrate all tissues in the body. A high accumulation of Cr(III) in all tissues and organs is a strong indication of the wide toxic potential of exposure to soluble hexavalent Cr in the drinking water and in the ambient environment."
1232187,Chen et al. 1998,The simulation of hexavalent chromium formation under various incineration conditions,"The formation of hexavalent chromium Cr(VI) during waste incineration processes is of interested because its carcinogenic characteristic. The objective of this study is to simulate the formation of Cr(VI) species under various operating temperatures and input waste compositions during incineration by a thermodynamic model. The results show that the major hexavalent chromium species are CrO2Cl2(g) and CrO3(g). Chlorine and oxygen can increase the formation of Cr(VI) species; while hydrogen, sulfur, sodium, and calcium can inhibit. The input waste composition has greater effect on the formation of hexavalent chromium species than operating temperature.","The simulation of hexavalent chromium formation under various incineration conditions Abs: The formation of hexavalent chromium Cr(VI) during waste incineration processes is of interested because its carcinogenic characteristic. The objective of this study is to simulate the formation of Cr(VI) species under various operating temperatures and input waste compositions during incineration by a thermodynamic model. The results show that the major hexavalent chromium species are CrO2Cl2(g) and CrO3(g). Chlorine and oxygen can increase the formation of Cr(VI) species; while hydrogen, sulfur, sodium, and calcium can inhibit. The input waste composition has greater effect on the formation of hexavalent chromium species than operating temperature."
1232186,Izzotti et al. 1998,"DNA fragmentation, DNA-protein crosslinks, 32P postlabeled nucleotidic modifications, and 8-hydroxy-2'-deoxyguanosine in the lung but not in the liver of rats receiving intratracheal instillations of chromium(VI). Chemoprevention by oral N-acetylcysteine","An in vivo study was carried out with the objectives of evaluating (a) the localization of DNA lesions resulting from exposure to chromium(VI) by the respiratory route, (b) the molecular nature of DNA alterations, and (c) modulation of DNA damage by a known chemopreventive agent. To this purpose, Sprague-Dawley rats received intratracheal instillations of sodium dichromate (0.25 mg/kg body weight) for three consecutive days, and the day after the last treatment lung and liver were removed for DNA purification. The results showed a selective localization of DNA lesions in the lung but not in the liver, which can be ascribed to toxicokinetics and metabolic characteristics of chromium(VI). DNA alterations included DNA-protein crosslinks, DNA fragmentation, nucleotidic modifications, and 8-hydroxy-2'-deoxyguanosine. The last two endpoints were evaluated, for the first time in chromium toxicology, by means of postlabeling procedures. This methodology was adapted to the detection of the DNA damage produced by those reactive oxygen species which result from the intracellular reduction of chromium(VI). The oral administration of the thiol N-acetylcysteine completely prevented any induction of DNA lesions in lung cells.","DNA fragmentation, DNA-protein crosslinks, 32P postlabeled nucleotidic modifications, and 8-hydroxy-2'-deoxyguanosine in the lung but not in the liver of rats receiving intratracheal instillations of chromium(VI). Chemoprevention by oral N-acetylcysteine Abs: An in vivo study was carried out with the objectives of evaluating (a) the localization of DNA lesions resulting from exposure to chromium(VI) by the respiratory route, (b) the molecular nature of DNA alterations, and (c) modulation of DNA damage by a known chemopreventive agent. To this purpose, Sprague-Dawley rats received intratracheal instillations of sodium dichromate (0.25 mg/kg body weight) for three consecutive days, and the day after the last treatment lung and liver were removed for DNA purification. The results showed a selective localization of DNA lesions in the lung but not in the liver, which can be ascribed to toxicokinetics and metabolic characteristics of chromium(VI). DNA alterations included DNA-protein crosslinks, DNA fragmentation, nucleotidic modifications, and 8-hydroxy-2'-deoxyguanosine. The last two endpoints were evaluated, for the first time in chromium toxicology, by means of postlabeling procedures. This methodology was adapted to the detection of the DNA damage produced by those reactive oxygen species which result from the intracellular reduction of chromium(VI). The oral administration of the thiol N-acetylcysteine completely prevented any induction of DNA lesions in lung cells."
1232185,Asmatullah and  Shakoori 1998,Embryotoxic and teratogenic effects of hexavalent chromium in developing chicks of Gallus domesticus,,Embryotoxic and teratogenic effects of hexavalent chromium in developing chicks of Gallus domesticus Abs: 
1232184,Dubrovskaya and  Wetterhahn 1998,Effects of Cr(VI) on the expression of the oxidative stress genes in human lung cells,"Intracellular metabolism of chromium(VI) [Cr(VI)] may lead to oxidative stress and this may account for the ability of Cr(VI) to act as a complete carcinogen. Therefore, we examined the effects of Cr(VI) treatment on the expression of oxidative stress genes in normal human lung LL 24 cells and human lung adenocarcinoma A549 cells. RT-PCR and northern blot analyses were used to determine the steady-state mRNA levels of catalase, glutathione S-transferase, glutathione reductase, Cu/Zn- and Mn-superoxide dismutases, glutathione peroxidase, NAD(P)H:quinone oxidoreductase, heme oxygenase and interleukin 8 in control cells and cells treated with 5-200 microM of Cr(VI). We found that only expression of the heme oxygenase gene is strongly elevated under the treatment with Cr(VI), and only in normal human lung LL 24 cells. Our data showed that even in the absence of Cr(VI) treatment, the level of heme oxygenase gene expression is much higher in A549 cells than in LL 24 cells. As glutathione is believed to play a protective role in cells against different forms of oxidative stress, we studied the correlation between intracellular glutathione levels and the inducibility of the heme oxygenase gene after treatment of cells with Cr(VI). Our results demonstrate that glutathione levels are increased by 35 % of control values in LL 24 cells treated with Cr(VI). The data obtained indicate that heme oxygenase, known to be a stress-inducible gene, may be involved in cellular pathways critical to the carcinogenic activity of Cr(VI) in normal human lung cells. Intracellular glutathione levels and reactive oxygen species do not appear to be primarily responsible for the stress response, induced by Cr(VI) in the studied human cells.","Effects of Cr(VI) on the expression of the oxidative stress genes in human lung cells Abs: Intracellular metabolism of chromium(VI) [Cr(VI)] may lead to oxidative stress and this may account for the ability of Cr(VI) to act as a complete carcinogen. Therefore, we examined the effects of Cr(VI) treatment on the expression of oxidative stress genes in normal human lung LL 24 cells and human lung adenocarcinoma A549 cells. RT-PCR and northern blot analyses were used to determine the steady-state mRNA levels of catalase, glutathione S-transferase, glutathione reductase, Cu/Zn- and Mn-superoxide dismutases, glutathione peroxidase, NAD(P)H:quinone oxidoreductase, heme oxygenase and interleukin 8 in control cells and cells treated with 5-200 microM of Cr(VI). We found that only expression of the heme oxygenase gene is strongly elevated under the treatment with Cr(VI), and only in normal human lung LL 24 cells. Our data showed that even in the absence of Cr(VI) treatment, the level of heme oxygenase gene expression is much higher in A549 cells than in LL 24 cells. As glutathione is believed to play a protective role in cells against different forms of oxidative stress, we studied the correlation between intracellular glutathione levels and the inducibility of the heme oxygenase gene after treatment of cells with Cr(VI). Our results demonstrate that glutathione levels are increased by 35 % of control values in LL 24 cells treated with Cr(VI). The data obtained indicate that heme oxygenase, known to be a stress-inducible gene, may be involved in cellular pathways critical to the carcinogenic activity of Cr(VI) in normal human lung cells. Intracellular glutathione levels and reactive oxygen species do not appear to be primarily responsible for the stress response, induced by Cr(VI) in the studied human cells."
1232183,Proctor et al. 1998,The prevalence of chromium allergy in the United States and its implications for setting soil cleanup: a cost-effectiveness case study,"Hexavalent chromium [Cr(VI)] elicits allergic contact dermatitis (ACD) among previously sensitized individuals, and some regulatory agencies have suggested the need for Cr(VI) soil standards that are protective of this health end point. To assess the cost effectiveness of implementing ACD-based standards, it is necessary to understand the prevalence of Cr(VI) sensitivity in the general population. More than 30 published studies from 1950 to 1997 were reviewed to determine the prevalence of Cr(VI) sensitivity. No random survey of the general United States (U.S.) population has been performed to date, but the prevalence of Cr(VI) sensitization among North American clinical cohorts (e.g., patients of dermatological clinics) was reported to be 1% in 1996. The prevalence of Cr(VI) sensitivity among the general U.S. population is estimated to be 0.08%. This estimate was calculated by dividing the current U.S. clinical prevalence estimate (1%) by the ratio of Cr(VI) sensitization in clinical vs general populations in The Netherlands (12). A retrospective cost/benefit analysis for sites in Jersey City, New Jersey, suggests that remediation of soils to protect against elicitation of ACD in sensitized individuals is not a cost-effective use of public health resources.","The prevalence of chromium allergy in the United States and its implications for setting soil cleanup: a cost-effectiveness case study Abs: Hexavalent chromium [Cr(VI)] elicits allergic contact dermatitis (ACD) among previously sensitized individuals, and some regulatory agencies have suggested the need for Cr(VI) soil standards that are protective of this health end point. To assess the cost effectiveness of implementing ACD-based standards, it is necessary to understand the prevalence of Cr(VI) sensitivity in the general population. More than 30 published studies from 1950 to 1997 were reviewed to determine the prevalence of Cr(VI) sensitivity. No random survey of the general United States (U.S.) population has been performed to date, but the prevalence of Cr(VI) sensitization among North American clinical cohorts (e.g., patients of dermatological clinics) was reported to be 1% in 1996. The prevalence of Cr(VI) sensitivity among the general U.S. population is estimated to be 0.08%. This estimate was calculated by dividing the current U.S. clinical prevalence estimate (1%) by the ratio of Cr(VI) sensitization in clinical vs general populations in The Netherlands (12). A retrospective cost/benefit analysis for sites in Jersey City, New Jersey, suggests that remediation of soils to protect against elicitation of ACD in sensitized individuals is not a cost-effective use of public health resources."
1232182,Al-Hamood et al. 1998,Sexual maturation and fertility of male and female mice exposed prenatally and postnatally to trivalent and hexavalent chromium compounds,"The reproductive toxicity of trivalent and hexavalent chromium compounds was investigated in male and female mice exposed to 1000 ppm chromium chloride and potassium dichromate via their mother during gestational and lactational periods. Fertility was reduced in male offspring exposed to either trivalent or hexavalent chromium compounds. Body weights and weights of testes, seminal vesicles and preputial glands were reduced in trivalent-exposed male offspring. The exposure of female mice offspring to trivalent and hexavalent chromium compounds delayed sexual maturation. Fertility was reduced in female offspring exposed to either trivalent or hexavalent chromium compounds. The exposure of female mice to hexavalent chromium compound reduced the number of implantations and viable fetuses respectively. Body weight and weights of ovaries and uteri were reduced in trivalent-exposed female offspring. The results indicate that under our experimental conditions, the exposure of male and female mice offspring to either trivalent or hexavalent chromium compounds during gestational and lactational periods impair reproductive functions and fertility in adulthood.","Sexual maturation and fertility of male and female mice exposed prenatally and postnatally to trivalent and hexavalent chromium compounds Abs: The reproductive toxicity of trivalent and hexavalent chromium compounds was investigated in male and female mice exposed to 1000 ppm chromium chloride and potassium dichromate via their mother during gestational and lactational periods. Fertility was reduced in male offspring exposed to either trivalent or hexavalent chromium compounds. Body weights and weights of testes, seminal vesicles and preputial glands were reduced in trivalent-exposed male offspring. The exposure of female mice offspring to trivalent and hexavalent chromium compounds delayed sexual maturation. Fertility was reduced in female offspring exposed to either trivalent or hexavalent chromium compounds. The exposure of female mice to hexavalent chromium compound reduced the number of implantations and viable fetuses respectively. Body weight and weights of ovaries and uteri were reduced in trivalent-exposed female offspring. The results indicate that under our experimental conditions, the exposure of male and female mice offspring to either trivalent or hexavalent chromium compounds during gestational and lactational periods impair reproductive functions and fertility in adulthood."
1232181,Bridgewater et al. 1998,Arrest of replication by mammalian DNA polymerases alpha and beta caused by chromium-DNA lesions,"We have previously shown that trivalent chromium, and hexavalent chromium in the presence of one of its primary in vivo reductants, ascorbate, can bind to DNA and form interstrand crosslinks capable of obstructing replication. This effect was demonstrated in vitro by using Sequenase Version 2.0 T7 DNA polymerase; its parent enzyme, the unmodified T7 DNA polymerase; and Escherichia coli polymerase I large (Klenow) fragment; and it was demonstrated ex vivo by using Taq polymerase and DNA from chromium-treated human lung cells as template. This study was performed to determine whether DNA-bound chromium affects mammalian DNA polymerases in the same manner. Two mammalian enzymes, DNA polymerase alpha and DNA polymerase beta, were used. DNA polymerase alpha is a processive enzyme believed to be the primary lagging-stand synthetase, whereas DNA polymerase beta is a non-processive enzyme believed to function in DNA repair by filling single stranded gaps one base at a time. DNA polymerase arrest assays were performed with each of these enzymes to replicate DNA with toxicologically relevant levels of chromium adducts produced by either trivalent chromium or hexavalent chromium and ascorbate. Both enzymes responded to chromium-DNA damage by arresting replication, and the arrests increased in a dose-dependent manner. Furthermore, the guanine-specific pattern of arrests produced when an exonuclease-free preparation of DNA polymerase beta was used corresponded exactly to the arrest patterns produced in vitro by the exonuclease-free enzyme Sequenase and ex vivo by Taq polymerase. These results suggest that replication arrest may be a common response of polymerases to DNA-chromium lesions and provide a plausible mechanism for the inhibition of DNA synthesis and S-phase cell-cycle delay that occurs in mammalian cells treated with genotoxic chromium compounds.","Arrest of replication by mammalian DNA polymerases alpha and beta caused by chromium-DNA lesions Abs: We have previously shown that trivalent chromium, and hexavalent chromium in the presence of one of its primary in vivo reductants, ascorbate, can bind to DNA and form interstrand crosslinks capable of obstructing replication. This effect was demonstrated in vitro by using Sequenase Version 2.0 T7 DNA polymerase; its parent enzyme, the unmodified T7 DNA polymerase; and Escherichia coli polymerase I large (Klenow) fragment; and it was demonstrated ex vivo by using Taq polymerase and DNA from chromium-treated human lung cells as template. This study was performed to determine whether DNA-bound chromium affects mammalian DNA polymerases in the same manner. Two mammalian enzymes, DNA polymerase alpha and DNA polymerase beta, were used. DNA polymerase alpha is a processive enzyme believed to be the primary lagging-stand synthetase, whereas DNA polymerase beta is a non-processive enzyme believed to function in DNA repair by filling single stranded gaps one base at a time. DNA polymerase arrest assays were performed with each of these enzymes to replicate DNA with toxicologically relevant levels of chromium adducts produced by either trivalent chromium or hexavalent chromium and ascorbate. Both enzymes responded to chromium-DNA damage by arresting replication, and the arrests increased in a dose-dependent manner. Furthermore, the guanine-specific pattern of arrests produced when an exonuclease-free preparation of DNA polymerase beta was used corresponded exactly to the arrest patterns produced in vitro by the exonuclease-free enzyme Sequenase and ex vivo by Taq polymerase. These results suggest that replication arrest may be a common response of polymerases to DNA-chromium lesions and provide a plausible mechanism for the inhibition of DNA synthesis and S-phase cell-cycle delay that occurs in mammalian cells treated with genotoxic chromium compounds."
1232180,Wang et al. 1999,Field method for the determination of hexavalent chromium by ultrasonication and strong anion-exchange solid-phase extraction,"A simple, fast, sensitive, and economical field method was developed and evaluated for the determination of hexavalent chromium (CrVI) in environmental and workplace air samples. By means of ultrasonic extraction in combination with a strong anion-exchange solid-phase extraction (SAE-SPE) technique, the filtration, isolation, and determination of CrVI in the presence of trivalent chromium (CrIII) and potential interferents was achieved. The method entails (1) ultrasonication in basic ammonium buffer solution to extract CrVI from environmental matrixes; (2) SAE-SPE to separate CrVI from CrIII and interferences; (3) elution/acidification of the eluate; (4) complexation of chromium with 1,5-diphenylcarbazide; and (5) spectrophotometric determination of the colored chromium-diphenylcarbazone complex. Several critical parameters were optimized in order to effect the extraction of both soluble (K2CrO4) and insoluble (PbCrO4) forms of CrVI without inducing CrIII oxidation or CrVI reduction. The method allowed for the dissolution and purification of CrVI from environmental and workplace air sample matrixes for up to 24 samples simultaneously in less than 90 min (including ultrasonication). The results demonstrated that the method was simple, fast, quantitative, and sufficiently sensitive for the determination of occupational exposures of CrVI. The method is applicable for on-site monitoring of CrVI in environmental and industrial hygiene samples.","Field method for the determination of hexavalent chromium by ultrasonication and strong anion-exchange solid-phase extraction Abs: A simple, fast, sensitive, and economical field method was developed and evaluated for the determination of hexavalent chromium (CrVI) in environmental and workplace air samples. By means of ultrasonic extraction in combination with a strong anion-exchange solid-phase extraction (SAE-SPE) technique, the filtration, isolation, and determination of CrVI in the presence of trivalent chromium (CrIII) and potential interferents was achieved. The method entails (1) ultrasonication in basic ammonium buffer solution to extract CrVI from environmental matrixes; (2) SAE-SPE to separate CrVI from CrIII and interferences; (3) elution/acidification of the eluate; (4) complexation of chromium with 1,5-diphenylcarbazide; and (5) spectrophotometric determination of the colored chromium-diphenylcarbazone complex. Several critical parameters were optimized in order to effect the extraction of both soluble (K2CrO4) and insoluble (PbCrO4) forms of CrVI without inducing CrIII oxidation or CrVI reduction. The method allowed for the dissolution and purification of CrVI from environmental and workplace air sample matrixes for up to 24 samples simultaneously in less than 90 min (including ultrasonication). The results demonstrated that the method was simple, fast, quantitative, and sufficiently sensitive for the determination of occupational exposures of CrVI. The method is applicable for on-site monitoring of CrVI in environmental and industrial hygiene samples."
1232179,Proctor et al. 1999,Need for improved science in standard setting for hexavalent chromium,,Need for improved science in standard setting for hexavalent chromium Abs: 
1232178,Yuann et al. 1999,"In vivo effects of ascorbate and glutathione on the uptake of chromium, formation of chromium(V), chromium-DNA binding and 8-hydroxy-2'-deoxyguanosine in liver and kidney of osteogenic disorder shionogi rats following treatment with chromium(VI)","Several previous in vitro studies have indicated that ascorbate and glutathione are the major reductants of Cr(VI) in cells. In order to evaluate the in vivo effects of ascorbate and glutathione on Cr(VI)-induced carcinogenesis, Cr uptake and the formation of Cr(V), Cr-DNA adducts and 8-hydroxy-2'-deoxyguanosine (8-OH-dG) were measured in the liver and kidney of Osteogenic Disorder Shionogi (ODS) rats that lack the ability to synthesize ascorbate. Despite a 10-fold difference in tissue ascorbate levels among different dietary ascorbate groups, the Cr(V) signal intensity, Cr uptake and total Cr-DNA binding were not affected in either organ. Treatment of ODS rats with Cr(VI) (10 mg/kg) had no substantial effect on the levels of ascorbate and glutathione in these tissues. The levels of Cr(V) and Cr-DNA binding were approximately 2-fold higher in the liver than in the kidney, although the levels of total Cr uptake were similar in both tissues. Cr uptake levels were significantly lower in the liver and kidney of ODS rats treated with high levels of ascorbate and a high dose of Cr(VI) (40 mg/kg), suggesting a detoxifying role played by plasma ascorbate. Similarly, modulation of glutathione levels by N-acetyl-L-cysteine, L-buthionine-S, R-sulfoximine or phorone in these animals by up to 2-fold had little or no consistent effect on Cr uptake, Cr-DNA binding, Cr(V) levels or 8-OH-dG formation in either organ. One possible explanation is that reduction of ascorbate and glutathione concentration to <10 and 50%, respectively, of normal in these two organs still provides threshold levels of these two reductants that are in excess of what is needed for significant reductive activation of Cr(VI). Alternatively, it is possible that ascorbate and glutathione do not play a major role in the formation of Cr(V), Cr-DNA binding or 8-OH-dG and that other cellular reductants, such as cysteine or other amino acids, might be more important reductants of Cr(VI) in vivo.","In vivo effects of ascorbate and glutathione on the uptake of chromium, formation of chromium(V), chromium-DNA binding and 8-hydroxy-2'-deoxyguanosine in liver and kidney of osteogenic disorder shionogi rats following treatment with chromium(VI) Abs: Several previous in vitro studies have indicated that ascorbate and glutathione are the major reductants of Cr(VI) in cells. In order to evaluate the in vivo effects of ascorbate and glutathione on Cr(VI)-induced carcinogenesis, Cr uptake and the formation of Cr(V), Cr-DNA adducts and 8-hydroxy-2'-deoxyguanosine (8-OH-dG) were measured in the liver and kidney of Osteogenic Disorder Shionogi (ODS) rats that lack the ability to synthesize ascorbate. Despite a 10-fold difference in tissue ascorbate levels among different dietary ascorbate groups, the Cr(V) signal intensity, Cr uptake and total Cr-DNA binding were not affected in either organ. Treatment of ODS rats with Cr(VI) (10 mg/kg) had no substantial effect on the levels of ascorbate and glutathione in these tissues. The levels of Cr(V) and Cr-DNA binding were approximately 2-fold higher in the liver than in the kidney, although the levels of total Cr uptake were similar in both tissues. Cr uptake levels were significantly lower in the liver and kidney of ODS rats treated with high levels of ascorbate and a high dose of Cr(VI) (40 mg/kg), suggesting a detoxifying role played by plasma ascorbate. Similarly, modulation of glutathione levels by N-acetyl-L-cysteine, L-buthionine-S, R-sulfoximine or phorone in these animals by up to 2-fold had little or no consistent effect on Cr uptake, Cr-DNA binding, Cr(V) levels or 8-OH-dG formation in either organ. One possible explanation is that reduction of ascorbate and glutathione concentration to <10 and 50%, respectively, of normal in these two organs still provides threshold levels of these two reductants that are in excess of what is needed for significant reductive activation of Cr(VI). Alternatively, it is possible that ascorbate and glutathione do not play a major role in the formation of Cr(V), Cr-DNA binding or 8-OH-dG and that other cellular reductants, such as cysteine or other amino acids, might be more important reductants of Cr(VI) in vivo."
1232177,Czakó-Vér et al. 1999,Hexavalent chromium uptake by sensitive and tolerant mutants of Schizosaccharomyces pombe,"Lysine and leucine auxotrophic, heterothallic (h+, h-) strains of Schizosaccharomyces pombe were used to obtain chromium (VI)-sensitive and -tolerant mutants by ultraviolet radiation-induced and nitrosoguanidine-induced mutagenesis. The minimal inhibitory concentrations of K2Cr2O7 on YEA media were 225 microM for the wild-type strain CW-6, 125 microM for the sensitive mutant CS-6.51 and 275 microM for the tolerant mutant CT-6.66. The mutants exhibited cross-sensitivity of various patterns to Cd2+, Cu2+, Ni2+, Zn2+ and VO3-(4). Cr(VI) was added to the actively growing cultures and the total chromium (TOCr) content of the cells was determined. The sensitive mutant exhibited a high bioaccumulation ability, with a dry biomass of 810 micrograms g-1 after 30 min, while the tolerant mutant had a significantly lower ability than the wild-type strain. In PIPES buffer, washed, lysine-starved biomasses were treated with 75 microM Cr(VI) and after 2 h, the TOCr and the organically bound chromium (OBCr) were determined. Under these conditions, the sensitive and tolerant mutants had the same TOCr content, 50% of which was OBCr. The wild-type strain exhibited a lower TOCr content than that of its mutants and only 35% of this was OBCr. The Cr(VI)-sensitivity was due to a significantly increased uptake of Cr(VI).","Hexavalent chromium uptake by sensitive and tolerant mutants of Schizosaccharomyces pombe Abs: Lysine and leucine auxotrophic, heterothallic (h+, h-) strains of Schizosaccharomyces pombe were used to obtain chromium (VI)-sensitive and -tolerant mutants by ultraviolet radiation-induced and nitrosoguanidine-induced mutagenesis. The minimal inhibitory concentrations of K2Cr2O7 on YEA media were 225 microM for the wild-type strain CW-6, 125 microM for the sensitive mutant CS-6.51 and 275 microM for the tolerant mutant CT-6.66. The mutants exhibited cross-sensitivity of various patterns to Cd2+, Cu2+, Ni2+, Zn2+ and VO3-(4). Cr(VI) was added to the actively growing cultures and the total chromium (TOCr) content of the cells was determined. The sensitive mutant exhibited a high bioaccumulation ability, with a dry biomass of 810 micrograms g-1 after 30 min, while the tolerant mutant had a significantly lower ability than the wild-type strain. In PIPES buffer, washed, lysine-starved biomasses were treated with 75 microM Cr(VI) and after 2 h, the TOCr and the organically bound chromium (OBCr) were determined. Under these conditions, the sensitive and tolerant mutants had the same TOCr content, 50% of which was OBCr. The wild-type strain exhibited a lower TOCr content than that of its mutants and only 35% of this was OBCr. The Cr(VI)-sensitivity was due to a significantly increased uptake of Cr(VI)."
1232176,Mattagajasingh and  Misra 1999,Analysis of EDTA-chelatable proteins from DNA-protein crosslinks induced by a carcinogenic chromium(VI) in cultured intact human cells,"DNA-protein crosslinks (DPCs) were induced in intact human leukemic T-lymphocyte MOLT4 cells or isolated nuclei by treatment with potassium chromate, chromium(III) chloride hexahydrate or x-rays. The proteins complexed to DNA were analyzed by two-dimensional SDS-polyacrylamide gel electrophoresis (PAGE). A group of identical non-histone proteins was crosslinked to DNA by any of the three treatments, except that a 51 kDa basic protein was additionally complexed to DNA when either potassium chromate or chromium(III) chloride hexahydrate was the crosslinking agent. Treatment of chromate-induced DNA-protein crosslinks with EDTA or thiourea followed by ultracentifugation dissociated the major proteins from the complex indicating that these proteins were crosslinked to DNA by direct participation of a EDTA-chelatable form of chromium such as Cr(III) through sulfur containing amino acid residues. The 51 kDa protein was not seen in the post-EDTA pellet but was present in the post-thiourea pellet, indicating that it was also crosslinked to DNA by Cr(III) through non-sulfur-containing amino acids. Digestion of x-rays-induced DPCs by DNase I also revealed this protein on two-dimensional gels indicating that the same protein was also crosslinked by oxidative mechanisms. The involvement of oxidative mechanisms in the crosslinking process was indicated as the majority of the proteins in chromate-induced DPCs were resistant to EDTA and thiourea treatment, and were found to crosslink to DNA when x-rays were used as the crosslinking agent. These results suggest that the chromate-induced DPCs are formed by the generation of reactive oxygen species during the intracellular chromate reduction as well as by the biologically generated Cr(III). About 19% of DNA-protein crosslinks actually involve Cr(III) crosslinking DNA to proteins, of which about 14% involve Cr(III) crosslinking DNA to proteins through non-sulfhydryl containing moieties and about 5% involve Cr(III) crosslinking DNA to sulfhydryl groups on proteins. The remaining 81% of DNA-protein crosslinks appear to be oxidatively crosslinked out of which about 45% appear to be through sulfhydryl groups and another 36% appear to be through non-sulfhydryl groups.","Analysis of EDTA-chelatable proteins from DNA-protein crosslinks induced by a carcinogenic chromium(VI) in cultured intact human cells Abs: DNA-protein crosslinks (DPCs) were induced in intact human leukemic T-lymphocyte MOLT4 cells or isolated nuclei by treatment with potassium chromate, chromium(III) chloride hexahydrate or x-rays. The proteins complexed to DNA were analyzed by two-dimensional SDS-polyacrylamide gel electrophoresis (PAGE). A group of identical non-histone proteins was crosslinked to DNA by any of the three treatments, except that a 51 kDa basic protein was additionally complexed to DNA when either potassium chromate or chromium(III) chloride hexahydrate was the crosslinking agent. Treatment of chromate-induced DNA-protein crosslinks with EDTA or thiourea followed by ultracentifugation dissociated the major proteins from the complex indicating that these proteins were crosslinked to DNA by direct participation of a EDTA-chelatable form of chromium such as Cr(III) through sulfur containing amino acid residues. The 51 kDa protein was not seen in the post-EDTA pellet but was present in the post-thiourea pellet, indicating that it was also crosslinked to DNA by Cr(III) through non-sulfur-containing amino acids. Digestion of x-rays-induced DPCs by DNase I also revealed this protein on two-dimensional gels indicating that the same protein was also crosslinked by oxidative mechanisms. The involvement of oxidative mechanisms in the crosslinking process was indicated as the majority of the proteins in chromate-induced DPCs were resistant to EDTA and thiourea treatment, and were found to crosslink to DNA when x-rays were used as the crosslinking agent. These results suggest that the chromate-induced DPCs are formed by the generation of reactive oxygen species during the intracellular chromate reduction as well as by the biologically generated Cr(III). About 19% of DNA-protein crosslinks actually involve Cr(III) crosslinking DNA to proteins, of which about 14% involve Cr(III) crosslinking DNA to proteins through non-sulfhydryl containing moieties and about 5% involve Cr(III) crosslinking DNA to sulfhydryl groups on proteins. The remaining 81% of DNA-protein crosslinks appear to be oxidatively crosslinked out of which about 45% appear to be through sulfhydryl groups and another 36% appear to be through non-sulfhydryl groups."
1232175,Caldeira et al. 1999,4-Chlorophenol degradation by a bacterial consortium: development of a granular activated carbon biofilm reactor,"A bacterial consortium that can degrade chloro- and nitrophenols has been isolated from the rhizosphere of Phragmitis communis. Degradation of 4-chlorophenol (4-CP) by a consortium attached to granular activated carbon (GAC) in a biofilm reactor was evaluated during both open and closed modes of operation. During the operation of the biofilm reactor, 4-CP was not detected in the column effluent, being either adsorbed to the GAC or biodegraded by the consortium. When 4-CP at 100 mg l-1 was fed to the column in open mode operation (20 mg g-1 GAC total supply), up to 27% was immediately available for biodegradation, the rest being adsorbed to the GAC. Biodegradation continued after the system was returned to closed mode operation, indicating that GAC bound 4-CP became available to the consortium. Biofilm batch cultures supplied with 10-216 mg 4-CP g-1 GAC suggested that a residual fraction of GAC-bound 4-CP was biologically unavailable. The consortium was able to metabolise 4-CP after perturbations by the addition of chromium (Cr VI) at 1-5 mg l-1 and nitrate at concentrations up to 400 mg l-1. The development of the biofilm structure was analysed by scanning electron microscopy and confocal laser scanning microscopy (CLSM) techniques. CLSM revealed a heterogeneous structure with a network of channels throughout the biofilm, partially occupied by microbial exopolymer structures.","4-Chlorophenol degradation by a bacterial consortium: development of a granular activated carbon biofilm reactor Abs: A bacterial consortium that can degrade chloro- and nitrophenols has been isolated from the rhizosphere of Phragmitis communis. Degradation of 4-chlorophenol (4-CP) by a consortium attached to granular activated carbon (GAC) in a biofilm reactor was evaluated during both open and closed modes of operation. During the operation of the biofilm reactor, 4-CP was not detected in the column effluent, being either adsorbed to the GAC or biodegraded by the consortium. When 4-CP at 100 mg l-1 was fed to the column in open mode operation (20 mg g-1 GAC total supply), up to 27% was immediately available for biodegradation, the rest being adsorbed to the GAC. Biodegradation continued after the system was returned to closed mode operation, indicating that GAC bound 4-CP became available to the consortium. Biofilm batch cultures supplied with 10-216 mg 4-CP g-1 GAC suggested that a residual fraction of GAC-bound 4-CP was biologically unavailable. The consortium was able to metabolise 4-CP after perturbations by the addition of chromium (Cr VI) at 1-5 mg l-1 and nitrate at concentrations up to 400 mg l-1. The development of the biofilm structure was analysed by scanning electron microscopy and confocal laser scanning microscopy (CLSM) techniques. CLSM revealed a heterogeneous structure with a network of channels throughout the biofilm, partially occupied by microbial exopolymer structures."
1232174,Ye et al. 1999,Role of reactive oxygen species and p53 in chromium(VI)-induced apoptosis,"Apoptosis is a programmed cell death mechanism to control cell number in tissues and to eliminate individual cells that may lead to disease states. The present study investigates chromium(VI) (Cr(VI))-induced apoptosis and the role of reactive oxygen species (ROS) and p53 in this response. Treatment of human lung epithelial cells (A549) with Cr(VI) caused apoptosis as measured by DNA fragmentation, mitochondria damage, and cell morphology. Cr(VI)-induced apoptosis is contributed to ROS generation, resulting from cellular reduction of Cr(VI) as measured by flow cytometric analysis of the stained cells, oxygen consumption, and electron spin resonance spin trapping. Scavengers of ROS, such as catalase, aspirin, and N-acetyl-L-cysteine, decreased Cr(VI)-induced apoptosis, whereas NADPH and glutathione reductase, enhancers of Cr(VI)-induced ROS generation, increased it. p53 is activated by Cr(VI), mostly by ROS-mediated free radical reactions. Cr(VI)-induced ROS generation occurred within a few minutes after Cr(VI) treatment of the cells, whereas p53 induction took at least 5 h. The level of Cr(VI)-induced apoptosis was similar in both p53-positive cells and p53-negative cells independent of p53 status in the early stage (0-3 h) of Cr(VI) treatment. However, at the later stage (3-24 h), the level of the apoptosis is higher in p53-positive cells than in p53-negative cells. These results suggest that ROS generated through Cr(VI) reduction is responsible to the early stage of apoptosis, whereas p53 contributes to the late stage of apoptosis and is responsible for the enhancement of Cr(VI)-induced apoptosis at this stage.","Role of reactive oxygen species and p53 in chromium(VI)-induced apoptosis Abs: Apoptosis is a programmed cell death mechanism to control cell number in tissues and to eliminate individual cells that may lead to disease states. The present study investigates chromium(VI) (Cr(VI))-induced apoptosis and the role of reactive oxygen species (ROS) and p53 in this response. Treatment of human lung epithelial cells (A549) with Cr(VI) caused apoptosis as measured by DNA fragmentation, mitochondria damage, and cell morphology. Cr(VI)-induced apoptosis is contributed to ROS generation, resulting from cellular reduction of Cr(VI) as measured by flow cytometric analysis of the stained cells, oxygen consumption, and electron spin resonance spin trapping. Scavengers of ROS, such as catalase, aspirin, and N-acetyl-L-cysteine, decreased Cr(VI)-induced apoptosis, whereas NADPH and glutathione reductase, enhancers of Cr(VI)-induced ROS generation, increased it. p53 is activated by Cr(VI), mostly by ROS-mediated free radical reactions. Cr(VI)-induced ROS generation occurred within a few minutes after Cr(VI) treatment of the cells, whereas p53 induction took at least 5 h. The level of Cr(VI)-induced apoptosis was similar in both p53-positive cells and p53-negative cells independent of p53 status in the early stage (0-3 h) of Cr(VI) treatment. However, at the later stage (3-24 h), the level of the apoptosis is higher in p53-positive cells than in p53-negative cells. These results suggest that ROS generated through Cr(VI) reduction is responsible to the early stage of apoptosis, whereas p53 contributes to the late stage of apoptosis and is responsible for the enhancement of Cr(VI)-induced apoptosis at this stage."
1232173,Vaglenov et al. 1999,Genotoxicity and radioresistance in electroplating workers exposed to chromium,"A biomonitoring study was carried out to investigate the genetic risk associated to occupational exposure to chromium. The induction of genetic damage was measured by analysing the frequency of micronuclei (MN) in peripheral blood lymphocytes. In addition to the 40 electroplater exposed workers who participated in the study, a group constituted by 18 volunteer donors, without exposure to chromium, was analysed as a control group. Measures of chromium levels at working place and in erythrocytes and urine were obtained, as indicators of exposure. The results from this study indicate that the blood from exposed workers contained higher levels of chromium, when compared with those obtained in the control group, and that a significant increase in the frequency of both the total number of MN and the number of binucleated cells carrying MN (BNMN) was detected. Furthermore, a good direct relationship was obtained between the amount of chromium present in air, erythrocytes or urine and the frequency of MN. To determine the existence of radioresistance as consequence of chromium exposure, the response of lymphocytes to the in vitro gamma-radiation was studied. The results of this experiment show a lower induction in the increase of the frequency of MN after challenge irradiation in the lymphocytes of chromium exposed workers, which should be indicative of an adaptive response.","Genotoxicity and radioresistance in electroplating workers exposed to chromium Abs: A biomonitoring study was carried out to investigate the genetic risk associated to occupational exposure to chromium. The induction of genetic damage was measured by analysing the frequency of micronuclei (MN) in peripheral blood lymphocytes. In addition to the 40 electroplater exposed workers who participated in the study, a group constituted by 18 volunteer donors, without exposure to chromium, was analysed as a control group. Measures of chromium levels at working place and in erythrocytes and urine were obtained, as indicators of exposure. The results from this study indicate that the blood from exposed workers contained higher levels of chromium, when compared with those obtained in the control group, and that a significant increase in the frequency of both the total number of MN and the number of binucleated cells carrying MN (BNMN) was detected. Furthermore, a good direct relationship was obtained between the amount of chromium present in air, erythrocytes or urine and the frequency of MN. To determine the existence of radioresistance as consequence of chromium exposure, the response of lymphocytes to the in vitro gamma-radiation was studied. The results of this experiment show a lower induction in the increase of the frequency of MN after challenge irradiation in the lymphocytes of chromium exposed workers, which should be indicative of an adaptive response."
1232172,Shi et al. 2000,Antioxidant properties of (-)-epicatechin-3-gallate and its inhibition of Cr(VI)-induced DNA damage and Cr(IV)- or TPA-stimulated NF-kappaB activation,"Electron spin resonance (ESR) spin trapping was utilized to investigate the scavenging effects on hydroxyl radicals (*OH) and superoxide radicals (O2*-) by (-)-epigallocatechin-3-gallate (EGCG), one of the major anticancer compounds in tea. The spin trap used was 5,5-dimethyl-pyrroline N-oxide (DMPO). The Fenton reaction (Fe2+ + H2O2--&gt;Fe3+ + *OH + OH-) was used as a source of *OH radicals. EGCG efficiently scavenges *OH radicals with reaction rate of 4.62 x 10(11) M(-1)sec(-1), which is an order of magnitude higher than several well recognized antioxidants, such as ascorbate, glutathione and cysteine. It also scavenges O2*- radicals as demonstrated by using xanthine and xanthine oxidase system as a source of O2*- radicals. Through its antioxidant properties, EGCG exhibited a protective effect against DNA damage induced by Cr(VI). EGCG also inhibited activation of nuclear transcription factor NF-kappaB induced by Cr(IV) and 12-o-tetradecanoylphorbol-13-acetate (TPA). The present studies provide a mechanistic basis for the reported anticarcinogenic properties of EGCG and related tea products.","Antioxidant properties of (-)-epicatechin-3-gallate and its inhibition of Cr(VI)-induced DNA damage and Cr(IV)- or TPA-stimulated NF-kappaB activation Abs: Electron spin resonance (ESR) spin trapping was utilized to investigate the scavenging effects on hydroxyl radicals (*OH) and superoxide radicals (O2*-) by (-)-epigallocatechin-3-gallate (EGCG), one of the major anticancer compounds in tea. The spin trap used was 5,5-dimethyl-pyrroline N-oxide (DMPO). The Fenton reaction (Fe2+ + H2O2--&gt;Fe3+ + *OH + OH-) was used as a source of *OH radicals. EGCG efficiently scavenges *OH radicals with reaction rate of 4.62 x 10(11) M(-1)sec(-1), which is an order of magnitude higher than several well recognized antioxidants, such as ascorbate, glutathione and cysteine. It also scavenges O2*- radicals as demonstrated by using xanthine and xanthine oxidase system as a source of O2*- radicals. Through its antioxidant properties, EGCG exhibited a protective effect against DNA damage induced by Cr(VI). EGCG also inhibited activation of nuclear transcription factor NF-kappaB induced by Cr(IV) and 12-o-tetradecanoylphorbol-13-acetate (TPA). The present studies provide a mechanistic basis for the reported anticarcinogenic properties of EGCG and related tea products."
1232171,Ning and  Grant 2000,The role of reduced glutathione and glutathione reductase in the cytotoxicity of chromium (VI) in osteoblasts,"It is accepted that to exert cytotoxicity and carcinogenicity chromium VI has to be reduced inside cells. The role of reduced glutathione (GSH) and glutathione reductase in the intracellular reduction of Cr VI was investigated using an immortalized rat osteoblast cell line, FFC. Alkaline phosphatase activity was the index of cytotoxicity measured. To investigate the role of GSH in Cr VI toxicity, GSH levels in the cells were elevated by pretreatment with L-cysteine, and depleted using buthionine sulfoximine (BSO), an inhibitor of GSH synthesis. Intracellular GSH levels were not depleted during the metabolism of Cr VI. Depletion of GSH by BSO caused the cells to be more resistant to the toxicity of Cr VI, indicating that GSH is involved in reduction of the Cr VI. Inhibition of glutathione reductase by carmustine (BCNU) partially protected against the cytotoxicity of Cr VI irrespective of the intracellular GSH. The cytotoxic response was similar if cells were pretreated with BCNU plus L-cysteine, or with BCNU plus BSO, although the GSH levels were markedly different. The results indicate that glutathione reductase plays an important role in the intracellular reduction of Cr VI in osteoblasts.","The role of reduced glutathione and glutathione reductase in the cytotoxicity of chromium (VI) in osteoblasts Abs: It is accepted that to exert cytotoxicity and carcinogenicity chromium VI has to be reduced inside cells. The role of reduced glutathione (GSH) and glutathione reductase in the intracellular reduction of Cr VI was investigated using an immortalized rat osteoblast cell line, FFC. Alkaline phosphatase activity was the index of cytotoxicity measured. To investigate the role of GSH in Cr VI toxicity, GSH levels in the cells were elevated by pretreatment with L-cysteine, and depleted using buthionine sulfoximine (BSO), an inhibitor of GSH synthesis. Intracellular GSH levels were not depleted during the metabolism of Cr VI. Depletion of GSH by BSO caused the cells to be more resistant to the toxicity of Cr VI, indicating that GSH is involved in reduction of the Cr VI. Inhibition of glutathione reductase by carmustine (BCNU) partially protected against the cytotoxicity of Cr VI irrespective of the intracellular GSH. The cytotoxic response was similar if cells were pretreated with BCNU plus L-cysteine, or with BCNU plus BSO, although the GSH levels were markedly different. The results indicate that glutathione reductase plays an important role in the intracellular reduction of Cr VI in osteoblasts."
1232170,Wang et al. 2000,The role of hydroxyl radical as a messenger in Cr(VI)-induced p53 activation,"The present study investigates whether reactive oxygen species (ROS) are involved in p53 activation, and if they are, which species is responsible for the activation. Our hypothesis is that hydroxyl radical (.OH) functions as a messenger for the activation of this tumor suppressor protein. Human lung epithelial cells (A549) were used to test this hypothesis. Cr(VI) was employed as the source of ROS due to its ability to generate a whole spectrum of ROS inside the cell. Cr(VI) is able to activate p53 by increasing the protein levels and enhancing both the DNA binding activity and transactivation ability of the protein. Increased cellular levels of superoxide radicals (O(2)(-).), hydrogen peroxide (H(2)O(2)), and.OH radicals were detected on the addition of Cr(VI) to the cells. Superoxide dismutase, by enhancing the production of H(2)O(2) from O(2)(-). radicals, increased p53 activity. Catalase, an H(2)O(2) scavenger, eliminated.OH radical generation and inhibited p53 activation. Sodium formate and aspirin,.OH radical scavengers, also suppressed p53 activation. Deferoxamine, a metal chelator, inhibited p53 activation by chelating Cr(V) to make it incapable of generating radicals from H(2)O(2). NADPH, which accelerated the one-electron reduction of Cr(VI) to Cr(V) and increased.OH radical generation, dramatically enhanced p53 activation. Thus.OH radical generated from Cr(VI) reduction in A549 cells is responsible for Cr(VI)-induced p53 activation.","The role of hydroxyl radical as a messenger in Cr(VI)-induced p53 activation Abs: The present study investigates whether reactive oxygen species (ROS) are involved in p53 activation, and if they are, which species is responsible for the activation. Our hypothesis is that hydroxyl radical (.OH) functions as a messenger for the activation of this tumor suppressor protein. Human lung epithelial cells (A549) were used to test this hypothesis. Cr(VI) was employed as the source of ROS due to its ability to generate a whole spectrum of ROS inside the cell. Cr(VI) is able to activate p53 by increasing the protein levels and enhancing both the DNA binding activity and transactivation ability of the protein. Increased cellular levels of superoxide radicals (O(2)(-).), hydrogen peroxide (H(2)O(2)), and.OH radicals were detected on the addition of Cr(VI) to the cells. Superoxide dismutase, by enhancing the production of H(2)O(2) from O(2)(-). radicals, increased p53 activity. Catalase, an H(2)O(2) scavenger, eliminated.OH radical generation and inhibited p53 activation. Sodium formate and aspirin,.OH radical scavengers, also suppressed p53 activation. Deferoxamine, a metal chelator, inhibited p53 activation by chelating Cr(V) to make it incapable of generating radicals from H(2)O(2). NADPH, which accelerated the one-electron reduction of Cr(VI) to Cr(V) and increased.OH radical generation, dramatically enhanced p53 activation. Thus.OH radical generated from Cr(VI) reduction in A549 cells is responsible for Cr(VI)-induced p53 activation."
1232169,Blasiak and  Kowalik 2000,A comparison of the in vitro genotoxicity of tri- and hexavalent chromium,"Chromium can be found in the environment in two main valence states: hexavalent (Cr(VI)) and trivalent (Cr(III)). Cr(VI) salts are well known human carcinogens, but the results from in vitro studies are often conflicting. Cr(VI) primarily enters the cells and undergoes metabolic reduction; however, the ultimate product of this reduction, Cr(III) predominates within the cell. In the present work, we compared the effects of tri- and hexavalent chromium on the DNA damage and repair in human lymphocytes using the alkaline single cell gel electrophoresis (comet assay). Potassium dichromate induced DNA damage in the lymphocytes, measured as the increase in comet tail moment. The effect was dose-dependent. Treated cells were able to recover within a 120-min incubation. Cr(III) caused greater DNA migration than Cr(VI). The lymphocytes did not show measurable DNA repair. Vitamin C at 50 microM reduced the extent of DNA migration. This was either due to a decrease in DNA strand breaks and/or alkali labile sites induced by Cr(VI) or to the formation of DNA crosslinks by Cr(VI) in the presence of vitamin C. Vitamin C, however, did not modify the effects of Cr(III). Catalase, an enzyme inactivating hydrogen peroxide, decreased the extent of DNA damage induced by Cr(VI) but not the one induced by Cr(III). Lymphocytes exposed to Cr(VI) and treated with endonuclease III, which recognizes oxidized pyrimidines, displayed greater extent of DNA damage than those not treated with the enzyme. Such an effect was not observed when Cr(III) was tested. The results obtained suggest that reactive oxygen species and hydrogen peroxide may be involved in the formation of DNA lesions by hexavalent chromium. The comet assay did not indicate the involvement of oxidative mechanisms in the DNA-damaging activity of trivalent chromium and we speculate that its binding to cellular ligands may play a role in its genotoxicity.","A comparison of the in vitro genotoxicity of tri- and hexavalent chromium Abs: Chromium can be found in the environment in two main valence states: hexavalent (Cr(VI)) and trivalent (Cr(III)). Cr(VI) salts are well known human carcinogens, but the results from in vitro studies are often conflicting. Cr(VI) primarily enters the cells and undergoes metabolic reduction; however, the ultimate product of this reduction, Cr(III) predominates within the cell. In the present work, we compared the effects of tri- and hexavalent chromium on the DNA damage and repair in human lymphocytes using the alkaline single cell gel electrophoresis (comet assay). Potassium dichromate induced DNA damage in the lymphocytes, measured as the increase in comet tail moment. The effect was dose-dependent. Treated cells were able to recover within a 120-min incubation. Cr(III) caused greater DNA migration than Cr(VI). The lymphocytes did not show measurable DNA repair. Vitamin C at 50 microM reduced the extent of DNA migration. This was either due to a decrease in DNA strand breaks and/or alkali labile sites induced by Cr(VI) or to the formation of DNA crosslinks by Cr(VI) in the presence of vitamin C. Vitamin C, however, did not modify the effects of Cr(III). Catalase, an enzyme inactivating hydrogen peroxide, decreased the extent of DNA damage induced by Cr(VI) but not the one induced by Cr(III). Lymphocytes exposed to Cr(VI) and treated with endonuclease III, which recognizes oxidized pyrimidines, displayed greater extent of DNA damage than those not treated with the enzyme. Such an effect was not observed when Cr(III) was tested. The results obtained suggest that reactive oxygen species and hydrogen peroxide may be involved in the formation of DNA lesions by hexavalent chromium. The comet assay did not indicate the involvement of oxidative mechanisms in the DNA-damaging activity of trivalent chromium and we speculate that its binding to cellular ligands may play a role in its genotoxicity."
1232166,Sutherland et al. 2000,Rats retain chromium in tissues following chronic ingestion of drinking water containing hexavalent chromium,"Humans have sometimes been exposed to as much as 10 ppm Cr(VI) in drinking water from contaminated wells. The risks to these individuals are not well understood because the digestive tract reduces some of the Cr(VI) to the less bioavailable Cr(III) prior to absorption, and the disposition of the remaining Cr(VI) has not been well studied. We determined tissue Cr concentrations in rats after chronic ingestion of Cr(VI) in drinking water at concentrations relevant to human exposure levels. Adult male and female Fischer 344 rats consumed ad libitum 0, 0.5, 3, or 10 ppm Cr(VI) as K2CrO4 in drinking water for 44 wk. Rats then were given deionized water 4-6 d prior to sample collection. Females given 3 or 10 ppm Cr(VI) consumed more Cr(VI) per unit of body weight than did males. Bone Cr concentrations were significantly elevated in rats that drank 10 ppm Cr(VI). Renal Cr concentrations were significantly elevated in male rats that drank 3 or 10 ppm Cr(VI) and in female rats dosed with 10 ppm Cr(VI). Female rats had elevated liver Cr concentrations after drinking 3 or 10 ppm Cr(VI). Testicular Cr concentrations were slightly elevated in rats that drank 10 ppm Cr(VI). Brain, ovarian, and whole-blood Cr concentrations were below detection limits in all exposure groups. Although tissue Cr accumulation may have resulted from absorption of Cr(III), it is poorly absorbed. Therefore, the increased tissue retention may also have resulted, in part, from increased absorption of Cr(VI) and its subsequent uptake from the systemic circulation.","Rats retain chromium in tissues following chronic ingestion of drinking water containing hexavalent chromium Abs: Humans have sometimes been exposed to as much as 10 ppm Cr(VI) in drinking water from contaminated wells. The risks to these individuals are not well understood because the digestive tract reduces some of the Cr(VI) to the less bioavailable Cr(III) prior to absorption, and the disposition of the remaining Cr(VI) has not been well studied. We determined tissue Cr concentrations in rats after chronic ingestion of Cr(VI) in drinking water at concentrations relevant to human exposure levels. Adult male and female Fischer 344 rats consumed ad libitum 0, 0.5, 3, or 10 ppm Cr(VI) as K2CrO4 in drinking water for 44 wk. Rats then were given deionized water 4-6 d prior to sample collection. Females given 3 or 10 ppm Cr(VI) consumed more Cr(VI) per unit of body weight than did males. Bone Cr concentrations were significantly elevated in rats that drank 10 ppm Cr(VI). Renal Cr concentrations were significantly elevated in male rats that drank 3 or 10 ppm Cr(VI) and in female rats dosed with 10 ppm Cr(VI). Female rats had elevated liver Cr concentrations after drinking 3 or 10 ppm Cr(VI). Testicular Cr concentrations were slightly elevated in rats that drank 10 ppm Cr(VI). Brain, ovarian, and whole-blood Cr concentrations were below detection limits in all exposure groups. Although tissue Cr accumulation may have resulted from absorption of Cr(III), it is poorly absorbed. Therefore, the increased tissue retention may also have resulted, in part, from increased absorption of Cr(VI) and its subsequent uptake from the systemic circulation."
1232165,Gardea-Torresdey et al. 2000,Characterization of Cr(VI) binding and reduction to Cr(III) by the agricultural byproducts of Avena monida (oat) biomass,"Chromium contamination of the environment has become an important issue due to the potential health threat it poses. Conventional technologies to clean up heavy metal ions from contaminated waters have been utilized, but these technologies are not cost-effective. However, the use of agricultural waste byproducts for the removal of Cr(VI) from contaminated waters may be a new cost-effective alternative. Oat byproducts from the Juarez Valley in Mexico were studied for the ability to bind Cr(VI) under different temperature and time conditions. The metal binding ability of oat byproducts was calculated from experimental data collected at temperatures of 8, 26, and 54 degrees C, and time exposures of 1, 6, 24, 48, and 72 h at each temperature. These results showed that the binding of Cr(VI) to oat biomass increased as time and temperature increased. The bound chromium was recovered from the oat biomass by treatment with 0.2M HCl. Through the use of X-ray absorption spectroscopy, the reduction of Cr(VI) to Cr(III) was determined to occur by the oat byproducts. These results indicate that the use of agricultural waste byproducts could be a better alternative for the removal and subsequent reduction of Cr(VI) to Cr(III) from contaminated waters.","Characterization of Cr(VI) binding and reduction to Cr(III) by the agricultural byproducts of Avena monida (oat) biomass Abs: Chromium contamination of the environment has become an important issue due to the potential health threat it poses. Conventional technologies to clean up heavy metal ions from contaminated waters have been utilized, but these technologies are not cost-effective. However, the use of agricultural waste byproducts for the removal of Cr(VI) from contaminated waters may be a new cost-effective alternative. Oat byproducts from the Juarez Valley in Mexico were studied for the ability to bind Cr(VI) under different temperature and time conditions. The metal binding ability of oat byproducts was calculated from experimental data collected at temperatures of 8, 26, and 54 degrees C, and time exposures of 1, 6, 24, 48, and 72 h at each temperature. These results showed that the binding of Cr(VI) to oat biomass increased as time and temperature increased. The bound chromium was recovered from the oat biomass by treatment with 0.2M HCl. Through the use of X-ray absorption spectroscopy, the reduction of Cr(VI) to Cr(III) was determined to occur by the oat byproducts. These results indicate that the use of agricultural waste byproducts could be a better alternative for the removal and subsequent reduction of Cr(VI) to Cr(III) from contaminated waters."
1232164,Zhitkovich et al. 2001,Non-oxidative mechanisms are responsible for the induction of mutagenesis by reduction of Cr(VI) with cysteine: role of ternary DNA adducts in Cr(III)-dependent mutagenesis,"Intracellular reduction of carcinogenic Cr(VI) generates Cr-DNA adducts formed through the coordination of Cr(III) to DNA phosphates (phosphotriester-type adduct). Here, we examined the role of Cr(III)-DNA adducts in mutagenesis induced by metabolism of Cr(VI) with cysteine. Reduction of Cr(VI) caused a strong oxidation of 2', 7'-dichlorofluoroscin (DCFH) and extensive Cr-DNA binding but no DNA breakage. Cr-DNA adducts induced unwinding of supercoiled plasmids and structural distortions in the DNA helix as detected by decreased ethidium bromide binding. Propagation of Cr-treated pSP189 plasmids in human fibroblasts led to a dose-dependent formation of the supF mutants and inhibition of replication. Blocking of Cr(III)-DNA binding by occupation of DNA phosphates with Mg(2+) or by sequestration of Cr(III) by inorganic phosphate or EDTA eliminated mutagenic responses and restored a normal yield of replicated plasmids. Dissociation of Cr(III) from DNA by a phosphate-based reversal procedure returned mutation frequency to background levels. The mutagenic responses at the different phases of the reduction reaction were unrelated to the amount of reduced Cr(VI) but reflected the number and the spectrum of Cr(III)-DNA adducts that were formed. Ternary cysteine-Cr(III)-DNA adducts were approximately 4-5 times more mutagenic than binary Cr(III)-DNA adducts. Although intermediate reaction products (CrV/IV, thiyl radicals) were capable of oxidizing DCFH, they were insufficiently reactive to damage DNA. Single-base substitutions at G/C pairs were the predominant type of Cr-induced mutations. The majority of mutations occurred at the sites where G had adjacent purine in the 3' or 5' position. Overall, our results present the first evidence that Cr(III)-DNA adducts play the dominant role in the mutagenicity caused by the metabolism of Cr(VI) by a biological reducing agent.","Non-oxidative mechanisms are responsible for the induction of mutagenesis by reduction of Cr(VI) with cysteine: role of ternary DNA adducts in Cr(III)-dependent mutagenesis Abs: Intracellular reduction of carcinogenic Cr(VI) generates Cr-DNA adducts formed through the coordination of Cr(III) to DNA phosphates (phosphotriester-type adduct). Here, we examined the role of Cr(III)-DNA adducts in mutagenesis induced by metabolism of Cr(VI) with cysteine. Reduction of Cr(VI) caused a strong oxidation of 2', 7'-dichlorofluoroscin (DCFH) and extensive Cr-DNA binding but no DNA breakage. Cr-DNA adducts induced unwinding of supercoiled plasmids and structural distortions in the DNA helix as detected by decreased ethidium bromide binding. Propagation of Cr-treated pSP189 plasmids in human fibroblasts led to a dose-dependent formation of the supF mutants and inhibition of replication. Blocking of Cr(III)-DNA binding by occupation of DNA phosphates with Mg(2+) or by sequestration of Cr(III) by inorganic phosphate or EDTA eliminated mutagenic responses and restored a normal yield of replicated plasmids. Dissociation of Cr(III) from DNA by a phosphate-based reversal procedure returned mutation frequency to background levels. The mutagenic responses at the different phases of the reduction reaction were unrelated to the amount of reduced Cr(VI) but reflected the number and the spectrum of Cr(III)-DNA adducts that were formed. Ternary cysteine-Cr(III)-DNA adducts were approximately 4-5 times more mutagenic than binary Cr(III)-DNA adducts. Although intermediate reaction products (CrV/IV, thiyl radicals) were capable of oxidizing DCFH, they were insufficiently reactive to damage DNA. Single-base substitutions at G/C pairs were the predominant type of Cr-induced mutations. The majority of mutations occurred at the sites where G had adjacent purine in the 3' or 5' position. Overall, our results present the first evidence that Cr(III)-DNA adducts play the dominant role in the mutagenicity caused by the metabolism of Cr(VI) by a biological reducing agent."
1232163,Nakano et al. 2001,Adsorption mechanism of hexavalent chromium by redox within condensed-tannin gel,"We have proposed a new recovery system of hexavalent chromium Cr(VI) that is of great toxicity utilizing condensed-tannin gels derived from a natural polymer with many polyhydroxyphenyl groups. The adsorption mechanism of Cr(VI) to the tannin molecules was clarified. The adsorption mechanism consists of four reaction steps; the esterification of chromate with tannin molecules, the reduction of Cr(VI) to trivalent chromium Cr(III), the formation of carboxyl group by the oxidation of tannin molecules and the ion exchange of the reduced Cr(III) with the carboxyl and hydroxyl groups. It was found in this recovery system that a large amount of proton was consumed accompanied with the reduction of Cr(VI) so that the acidic solution containing Cr(VI) was transferred automatically to neutral one by choosing an appropriate initial pH. The carboxyl group which was created by the oxidation of tannin molecules parallel to the reduction of Cr(VI) to Cr(III) contributed to an increase in the ion-exchange sites of the reduced Cr(III). The maximum adsorption capacity of Cr(VI) reached 287 mg Cr/g dry tannin gel under the conditions of 0.77 water content of tannin gel and the initial pH = 2. This adsorption capacity was five to ten times higher than that obtained by the ion exchange between ordinary Cr(III) and tannin molecules for the tannin gels prepared under similar conditions. The system proposed here will provide an important information on a zero-emission-oriented process because it has such advantages as higher adsorption capacity of chromium and lower volume of secondary wastes compared with conventional process.","Adsorption mechanism of hexavalent chromium by redox within condensed-tannin gel Abs: We have proposed a new recovery system of hexavalent chromium Cr(VI) that is of great toxicity utilizing condensed-tannin gels derived from a natural polymer with many polyhydroxyphenyl groups. The adsorption mechanism of Cr(VI) to the tannin molecules was clarified. The adsorption mechanism consists of four reaction steps; the esterification of chromate with tannin molecules, the reduction of Cr(VI) to trivalent chromium Cr(III), the formation of carboxyl group by the oxidation of tannin molecules and the ion exchange of the reduced Cr(III) with the carboxyl and hydroxyl groups. It was found in this recovery system that a large amount of proton was consumed accompanied with the reduction of Cr(VI) so that the acidic solution containing Cr(VI) was transferred automatically to neutral one by choosing an appropriate initial pH. The carboxyl group which was created by the oxidation of tannin molecules parallel to the reduction of Cr(VI) to Cr(III) contributed to an increase in the ion-exchange sites of the reduced Cr(III). The maximum adsorption capacity of Cr(VI) reached 287 mg Cr/g dry tannin gel under the conditions of 0.77 water content of tannin gel and the initial pH = 2. This adsorption capacity was five to ten times higher than that obtained by the ion exchange between ordinary Cr(III) and tannin molecules for the tannin gels prepared under similar conditions. The system proposed here will provide an important information on a zero-emission-oriented process because it has such advantages as higher adsorption capacity of chromium and lower volume of secondary wastes compared with conventional process."
1232161,Travacio et al. 2001,Chromium (VI) induces oxidative stress in the mouse brain,"Potassium dichromate was given to female Swiss mice (25 mg/kg per day) orally in water for 1-3 days. Brain homogenates were prepared to evaluate the occurrence of oxidative stress in this organ through the measurement of the antioxidant defense levels. and the extent of lipid peroxidation. In addition, mitochondrial fractions were isolated from brain homogenates to determine the production of reactive oxygen species in this subcellular fraction. The administration of potassium dichromate for 3 days caused increases of 72 and 74% in superoxide dismutase and catalase activities, respectively, in the homogenates. The treatment with this metal for 3 days increased brain homogenate chemiluminescence and thiobarbituric acid-reactive substances by 34 and 29%, respectively. The brain contents of the non-enzymatic antioxidants alpha-tocopherol and sulfhydryl groups decreased by 35 and 32%, respectively. Ascorbic acid levels were not modified by the administration of potassium dichromate. Finally, there was a significant increment in the mitochondrial production of oxidants in the brain of treated mice as compared with controls. These results suggest that chromium(VI) produces an increased formation of reactive oxygen species and brain lipid peroxidation. The increase in the antioxidant enzyme activities reflects an adaptive response against oxidative stress, while the reduction in the levels of non-enzymatic antioxidants might be due to their reaction with reactive oxygen species generated during the metabolism of chromium(VI).","Chromium (VI) induces oxidative stress in the mouse brain Abs: Potassium dichromate was given to female Swiss mice (25 mg/kg per day) orally in water for 1-3 days. Brain homogenates were prepared to evaluate the occurrence of oxidative stress in this organ through the measurement of the antioxidant defense levels. and the extent of lipid peroxidation. In addition, mitochondrial fractions were isolated from brain homogenates to determine the production of reactive oxygen species in this subcellular fraction. The administration of potassium dichromate for 3 days caused increases of 72 and 74% in superoxide dismutase and catalase activities, respectively, in the homogenates. The treatment with this metal for 3 days increased brain homogenate chemiluminescence and thiobarbituric acid-reactive substances by 34 and 29%, respectively. The brain contents of the non-enzymatic antioxidants alpha-tocopherol and sulfhydryl groups decreased by 35 and 32%, respectively. Ascorbic acid levels were not modified by the administration of potassium dichromate. Finally, there was a significant increment in the mitochondrial production of oxidants in the brain of treated mice as compared with controls. These results suggest that chromium(VI) produces an increased formation of reactive oxygen species and brain lipid peroxidation. The increase in the antioxidant enzyme activities reflects an adaptive response against oxidative stress, while the reduction in the levels of non-enzymatic antioxidants might be due to their reaction with reactive oxygen species generated during the metabolism of chromium(VI)."
1232160,Steinpress and  Ward 2001,The scientific process and Hollywood: the case of hexavalent chromium,,The scientific process and Hollywood: the case of hexavalent chromium Abs: 
1232159,Szulczewski et al. 2001,XANES spectroscopy studies of Cr(VI) reduction by thiols in organosulfur compounds and humic substances,The reduction of Cr(VI) by the thiol-containing compounds cysteine and glutathione and by reduced sulfur in humic substances was monitored with sulfur and chromium X-ray absorption near-edge structure (XANES) spectroscopy in chromium-contaminated soils. Reaction of humic acids with Cr(VI) resulted in a reduction of the peak area of thiols and an increase in the peak area of disulfides in the sulfur XANES spectra. Analysis of the sulfur XANES spectra in various systems indicates that the reduction of Cr(VI) by humic substances involves a thiol/disulfide redox couple analogous to that of the Cr(VI) reduction by the simple thiol-containing compounds cysteine and glutathione. A fraction of the hexavalent chromium present in industrially-contaminated soils was not reducible by thiols. Reduction of Cr(VI) to Cr(III) in soils by thiols has little effect on the pH of the system in contrast to the pH decrease resulting from reduction by Fe(II).,XANES spectroscopy studies of Cr(VI) reduction by thiols in organosulfur compounds and humic substances Abs: The reduction of Cr(VI) by the thiol-containing compounds cysteine and glutathione and by reduced sulfur in humic substances was monitored with sulfur and chromium X-ray absorption near-edge structure (XANES) spectroscopy in chromium-contaminated soils. Reaction of humic acids with Cr(VI) resulted in a reduction of the peak area of thiols and an increase in the peak area of disulfides in the sulfur XANES spectra. Analysis of the sulfur XANES spectra in various systems indicates that the reduction of Cr(VI) by humic substances involves a thiol/disulfide redox couple analogous to that of the Cr(VI) reduction by the simple thiol-containing compounds cysteine and glutathione. A fraction of the hexavalent chromium present in industrially-contaminated soils was not reducible by thiols. Reduction of Cr(VI) to Cr(III) in soils by thiols has little effect on the pH of the system in contrast to the pH decrease resulting from reduction by Fe(II).
1232158,Wielinga et al. 2001,Iron promoted reduction of chromate by dissimilatory iron-reducing bacteria,"Chromate is a priority pollutant within the U.S. and many other countries, the hazard of which can be mitigated by reduction to the trivalent form of chromium. Here we elucidate the reduction of Cr(VI) to Cr(III) via a closely coupled, biotic-abiotic reductive pathway under iron-reducing conditions. Injection of chromate into stirred-flow reactors containing Shewanella alga strain BrY and iron (hydr)oxides of varying stabilities results in complete reduction to Cr(III). The maximum sustainable Cr(VI) reduction rate was 5.5 micrograms CrVI.mg-cell-1.h-1 within ferric (hydr)oxide suspensions (surface area 10 m2). In iron limited systems (having HEPES as a buffer), iron was cycled suggesting it acts in a catalytic-type manner for the bacterial reduction of Cr(VI). BrY also reduced Cr(VI) directly; however, the rate of direct (enzymatic) reduction is considerably slower than by Fe(II)(aq) and is inhibited within 20 h due to chromate toxicity. Thus, dissimilatory iron reduction may provide a primary pathway for the sequestration and detoxification of chromate in anaerobic soils and water.","Iron promoted reduction of chromate by dissimilatory iron-reducing bacteria Abs: Chromate is a priority pollutant within the U.S. and many other countries, the hazard of which can be mitigated by reduction to the trivalent form of chromium. Here we elucidate the reduction of Cr(VI) to Cr(III) via a closely coupled, biotic-abiotic reductive pathway under iron-reducing conditions. Injection of chromate into stirred-flow reactors containing Shewanella alga strain BrY and iron (hydr)oxides of varying stabilities results in complete reduction to Cr(III). The maximum sustainable Cr(VI) reduction rate was 5.5 micrograms CrVI.mg-cell-1.h-1 within ferric (hydr)oxide suspensions (surface area 10 m2). In iron limited systems (having HEPES as a buffer), iron was cycled suggesting it acts in a catalytic-type manner for the bacterial reduction of Cr(VI). BrY also reduced Cr(VI) directly; however, the rate of direct (enzymatic) reduction is considerably slower than by Fe(II)(aq) and is inhibited within 20 h due to chromate toxicity. Thus, dissimilatory iron reduction may provide a primary pathway for the sequestration and detoxification of chromate in anaerobic soils and water."
1232157,Samanta et al. 2001,Continuous automated measurement of hexavalent chromium in airborne particulate matter,"An automated continuous instrument for the collection and measurement of aerosol Cr(VI) is described. The system alternately collects the sample on one of two glass fiber filters. After 15-min sample collection on one filter, the sampling switches over to the second filter. The freshly sampled filter is washed for 8.5 min, and the washings are preconcentrated on a minicolumn packed with anion exchange resin. The washed filter is dried with filtered hot air for the next 6.5 min so that it is ready for sampling at the end of the 15-min cycle. The preconcentrated Cr(VI) on the column is eluted with 0.1 M sodium perchlorate and then reacted with sym-1,5-diphenylcarbazide prior to absorbance detection with a light emitting diode-based dedicated flow-through absorbance detector. The detection limit (S/N = 3) is 5 ng of Cr(VI)/m3, orders of magnitude lower than current regulatory requirements. The instrument operates unattended over long periods. In continuous round-the-clock operation, filter replacement frequency is every 24-72 h, depending on dust loading. The system is portable for facile field deployment and permits fully automated rapid determinations at a very low analysis cost per sample.","Continuous automated measurement of hexavalent chromium in airborne particulate matter Abs: An automated continuous instrument for the collection and measurement of aerosol Cr(VI) is described. The system alternately collects the sample on one of two glass fiber filters. After 15-min sample collection on one filter, the sampling switches over to the second filter. The freshly sampled filter is washed for 8.5 min, and the washings are preconcentrated on a minicolumn packed with anion exchange resin. The washed filter is dried with filtered hot air for the next 6.5 min so that it is ready for sampling at the end of the 15-min cycle. The preconcentrated Cr(VI) on the column is eluted with 0.1 M sodium perchlorate and then reacted with sym-1,5-diphenylcarbazide prior to absorbance detection with a light emitting diode-based dedicated flow-through absorbance detector. The detection limit (S/N = 3) is 5 ng of Cr(VI)/m3, orders of magnitude lower than current regulatory requirements. The instrument operates unattended over long periods. In continuous round-the-clock operation, filter replacement frequency is every 24-72 h, depending on dust loading. The system is portable for facile field deployment and permits fully automated rapid determinations at a very low analysis cost per sample."
1232156,Pattison et al. 2001,Chromium(VI) reduction by catechol(amine)s results in DNA cleavage in vitro: relevance to chromium genotoxicity,"Catechols are found extensively in nature both as essential biomolecules and as the byproducts of normal oxidative damage of amino acids and proteins. They are also present in cigarette smoke and other atmospheric pollutants. Here, the interactions of reactive species generated in Cr(VI)/catechol(amine) mixtures with plasmid DNA have been investigated to model a potential route to Cr(VI)-induced genotoxicity. Reduction of Cr(VI) by 3,4-dihydroxyphenylalanine (DOPA) (1), dopamine (2), or adrenaline (3) produces species that cause extensive DNA damage, but the products of similar reactions with catechol (4) or 4-tert-butylcatechol (5) do not damage DNA. The Cr(VI)/catechol(amine) reactions have been studied at low added H(2)O(2) concentrations, which lead to enhanced DNA cleavage with 1 and induce DNA cleavage with 4. The Cr(V) and organic intermediates generated by the reactions of Cr(VI) with 1 or 4 in the presence of H(2)O(2) were characterized by EPR spectroscopy. The detected signals were assigned to Cr(V)-catechol, Cr(V)-peroxo, and mixed Cr(V)-catechol-peroxo complexes. Oxygen consumption during the reactions of Cr(VI) with 1, 2, 4, and 5 was studied, and H(2)O(2) production was quantified. Reactions of Cr(VI) with 1 and 2, but not 4 and 5, consume considerable amounts of dissolved O(2), and give extensive H(2)O(2) production. Extents of oxygen consumption and H(2)O(2) production during the reaction of Cr(VI) with enzymatically generated 1 and N-acetyl-DOPA (from the reaction of Tyr and N-acetyl-Tyr with tyrosinase, respectively) were correlated with the DNA cleaving abilities of the products of these reactions. The reaction of Cr(VI) with enzymatically generated 1 produced significant amounts of H(2)O(2) and caused significant DNA damage, but the N-acetyl-DOPA did not. The extent of in vitro DNA damage is reduced considerably by treatment of the Cr(VI)/catechol(amine) mixtures with catalase, which shows that the DNA damage is H(2)O(2)-dependent and that the major reactive intermediates are likely to be Cr(V)-peroxo and mixed Cr(V)-catechol-peroxo complexes, rather than Cr(V)-catechol intermediates.","Chromium(VI) reduction by catechol(amine)s results in DNA cleavage in vitro: relevance to chromium genotoxicity Abs: Catechols are found extensively in nature both as essential biomolecules and as the byproducts of normal oxidative damage of amino acids and proteins. They are also present in cigarette smoke and other atmospheric pollutants. Here, the interactions of reactive species generated in Cr(VI)/catechol(amine) mixtures with plasmid DNA have been investigated to model a potential route to Cr(VI)-induced genotoxicity. Reduction of Cr(VI) by 3,4-dihydroxyphenylalanine (DOPA) (1), dopamine (2), or adrenaline (3) produces species that cause extensive DNA damage, but the products of similar reactions with catechol (4) or 4-tert-butylcatechol (5) do not damage DNA. The Cr(VI)/catechol(amine) reactions have been studied at low added H(2)O(2) concentrations, which lead to enhanced DNA cleavage with 1 and induce DNA cleavage with 4. The Cr(V) and organic intermediates generated by the reactions of Cr(VI) with 1 or 4 in the presence of H(2)O(2) were characterized by EPR spectroscopy. The detected signals were assigned to Cr(V)-catechol, Cr(V)-peroxo, and mixed Cr(V)-catechol-peroxo complexes. Oxygen consumption during the reactions of Cr(VI) with 1, 2, 4, and 5 was studied, and H(2)O(2) production was quantified. Reactions of Cr(VI) with 1 and 2, but not 4 and 5, consume considerable amounts of dissolved O(2), and give extensive H(2)O(2) production. Extents of oxygen consumption and H(2)O(2) production during the reaction of Cr(VI) with enzymatically generated 1 and N-acetyl-DOPA (from the reaction of Tyr and N-acetyl-Tyr with tyrosinase, respectively) were correlated with the DNA cleaving abilities of the products of these reactions. The reaction of Cr(VI) with enzymatically generated 1 produced significant amounts of H(2)O(2) and caused significant DNA damage, but the N-acetyl-DOPA did not. The extent of in vitro DNA damage is reduced considerably by treatment of the Cr(VI)/catechol(amine) mixtures with catalase, which shows that the DNA damage is H(2)O(2)-dependent and that the major reactive intermediates are likely to be Cr(V)-peroxo and mixed Cr(V)-catechol-peroxo complexes, rather than Cr(V)-catechol intermediates."
1232155,Lehmann et al. 2001,Modelling the sorption of metals from aqueous solutions on goethite fixed-beds,"The research on separation methods of toxic metals from wastewater streams is continuous and intensive and, among them, sorption processes are considered of particular importance, mainly due to their effectiveness. The sorption of chromate anions and zinc cations from dilute aqueous solutions using a packed-bed (column configuration) of synthesised granulated goethite was investigated in the present study. The examined parameters during this investigation were the following: (1) the initial pH value of metal-laden aqueous solution (two representative values at acidic pH, 3.5 and 5.0, were tested); (2) the quantity of sorbent in the column, corresponding to bed height; and (3) the influence of ethylene diamine tetra acetic acid (EDTA) addition, a common, strong chelating agent. The Bed Depth-Service Time model has been applied to the sorption results in order to model the column operation. The removal efficiency of Cr(VI) anions by the sorptive column was found to be higher than that of Zn(II) cations. The presence of EDTA caused a certain decrease of removal efficiency for the case of hexavalent chromium, due to competition for the same sorption sites, while the removal of divalent zinc was increased, due to variation of cation speciation.","Modelling the sorption of metals from aqueous solutions on goethite fixed-beds Abs: The research on separation methods of toxic metals from wastewater streams is continuous and intensive and, among them, sorption processes are considered of particular importance, mainly due to their effectiveness. The sorption of chromate anions and zinc cations from dilute aqueous solutions using a packed-bed (column configuration) of synthesised granulated goethite was investigated in the present study. The examined parameters during this investigation were the following: (1) the initial pH value of metal-laden aqueous solution (two representative values at acidic pH, 3.5 and 5.0, were tested); (2) the quantity of sorbent in the column, corresponding to bed height; and (3) the influence of ethylene diamine tetra acetic acid (EDTA) addition, a common, strong chelating agent. The Bed Depth-Service Time model has been applied to the sorption results in order to model the column operation. The removal efficiency of Cr(VI) anions by the sorptive column was found to be higher than that of Zn(II) cations. The presence of EDTA caused a certain decrease of removal efficiency for the case of hexavalent chromium, due to competition for the same sorption sites, while the removal of divalent zinc was increased, due to variation of cation speciation."
1232154,de Lemos et al. 2001,Evaluation of basal micronucleus frequency and hexavalent chromium effects in fish erythrocytes,"Hexavalent chromium (Cr [VI]) genotoxicity was studied using fish micronucleus analysis in peripheral blood erythrocytes from Pimephales promelas, the fathead minnow. Forty-five- to 60-d-old fish were used to assess the spontaneous level of genotoxic damage. The genotoxic effect of Cr (VI) obtained from potassium dichromate (K2Cr2O7) in tests performed for 7-, 14-, and 21-d exposure periods was estimated. Significant micronucleated erythrocyte (MNE) induction was detected in fish exposed for 7 d to 2.5 mg/L of Cr (VI), and induction decreased after 21 d of exposure. The results suggest a handling effect in fish manipulated compared to those not manipulated, thus demonstrating the importance of including parallel negative controls in experimental design. Basal levels of MNE are reported, providing laboratory values for future assay quality control. The importance of determining the period with the highest expression of the genotoxic effects in this assay system was also confirmed.","Evaluation of basal micronucleus frequency and hexavalent chromium effects in fish erythrocytes Abs: Hexavalent chromium (Cr [VI]) genotoxicity was studied using fish micronucleus analysis in peripheral blood erythrocytes from Pimephales promelas, the fathead minnow. Forty-five- to 60-d-old fish were used to assess the spontaneous level of genotoxic damage. The genotoxic effect of Cr (VI) obtained from potassium dichromate (K2Cr2O7) in tests performed for 7-, 14-, and 21-d exposure periods was estimated. Significant micronucleated erythrocyte (MNE) induction was detected in fish exposed for 7 d to 2.5 mg/L of Cr (VI), and induction decreased after 21 d of exposure. The results suggest a handling effect in fish manipulated compared to those not manipulated, thus demonstrating the importance of including parallel negative controls in experimental design. Basal levels of MNE are reported, providing laboratory values for future assay quality control. The importance of determining the period with the highest expression of the genotoxic effects in this assay system was also confirmed."
1232152,S Bai and  Abraham 2001,Biosorption of Cr (VI) from aqueous solution by Rhizopus nigricans,"The study was aimed to quantify the Cr sorption ability of powdered biomass of Rhizopus nigricans at the best operating conditions. The influence of solution pH, agitation, Cr (VI) concentration, biomass dosage, contact time, biomass particle size and temperature were studied. The optimum pH for biosorption of Cr (VI) was found to be 2.0. Higher adsorption percentage was noted at lower initial concentrations of Cr ions, while the adsorption capacity of the biomass increased with increasing concentration of ions. Optimum biomass dosage was observed as 0.5% (w/v). More than 75% of the ions were removed within 30 min of contact and maximum removal was obtained after 8 h. Biomass particles of smaller size (90 microm) gave maximum adsorption (99.2%) at 100 mg/l concentration. The adsorption capacity increased with increase in temperature and agitation speed and the optimum were determined as 45 degrees C at 120 rpm. Freundlich and Langmuir isotherms were used to evaluate the data and the regression constants were derived. The adsorption rate constant values (Kad) were calculated for different initial concentration of Cr ions and the sorption was found to be higher at lower concentration (100 mg/l) of metal ion.","Biosorption of Cr (VI) from aqueous solution by Rhizopus nigricans Abs: The study was aimed to quantify the Cr sorption ability of powdered biomass of Rhizopus nigricans at the best operating conditions. The influence of solution pH, agitation, Cr (VI) concentration, biomass dosage, contact time, biomass particle size and temperature were studied. The optimum pH for biosorption of Cr (VI) was found to be 2.0. Higher adsorption percentage was noted at lower initial concentrations of Cr ions, while the adsorption capacity of the biomass increased with increasing concentration of ions. Optimum biomass dosage was observed as 0.5% (w/v). More than 75% of the ions were removed within 30 min of contact and maximum removal was obtained after 8 h. Biomass particles of smaller size (90 microm) gave maximum adsorption (99.2%) at 100 mg/l concentration. The adsorption capacity increased with increase in temperature and agitation speed and the optimum were determined as 45 degrees C at 120 rpm. Freundlich and Langmuir isotherms were used to evaluate the data and the regression constants were derived. The adsorption rate constant values (Kad) were calculated for different initial concentration of Cr ions and the sorption was found to be higher at lower concentration (100 mg/l) of metal ion."
1232151,Lapuma et al. 2001,Chromate concentration bias in primer paint particles,"Chromate-containing primer paints are used to prevent corrosion on metal surfaces. Chromate contains hexavalent chromium (Cr6+), a human carcinogen. The objective of this research was to determine if there is a bias in the fraction of chromate found in various particle sizes generated during primer painting operations. A solvent-based, aviation primer paint was sprayed using a high-volume, low-pressure spray gun. Paint particles were collected and separated by size with seven-stage cascade impactors. It was determined that particles with a mass aerodynamic diameter &lt; 2.0 microm contained significantly less Cr6+ per dry weight of paint than particles &gt; 2.0 microm (P &lt; 0.001). The median concentration of Cr6+ in particles &lt; 2.0 microm is 18 micro g of Cr/mg of dry paint and the median concentration for particles &gt; 2.0 microm is 70 microg of Cr/mg of dry paint. The mixed paint contains 18.75% strontium chromate, which equates to a ratio of 67 microg of Cr/mg of dry paint. Particles &gt; 2.0 microm are more likely to impact in the upper tracheobronchial regions of the lung where mucociliary clearance is relatively rapid. Additionally, chromate emissions from spraying operations may be overestimated because larger particles, which are more easily trapped on an air filter, contain more chromate than the smaller particles, which are more likely to bypass an air filter.","Chromate concentration bias in primer paint particles Abs: Chromate-containing primer paints are used to prevent corrosion on metal surfaces. Chromate contains hexavalent chromium (Cr6+), a human carcinogen. The objective of this research was to determine if there is a bias in the fraction of chromate found in various particle sizes generated during primer painting operations. A solvent-based, aviation primer paint was sprayed using a high-volume, low-pressure spray gun. Paint particles were collected and separated by size with seven-stage cascade impactors. It was determined that particles with a mass aerodynamic diameter &lt; 2.0 microm contained significantly less Cr6+ per dry weight of paint than particles &gt; 2.0 microm (P &lt; 0.001). The median concentration of Cr6+ in particles &lt; 2.0 microm is 18 micro g of Cr/mg of dry paint and the median concentration for particles &gt; 2.0 microm is 70 microg of Cr/mg of dry paint. The mixed paint contains 18.75% strontium chromate, which equates to a ratio of 67 microg of Cr/mg of dry paint. Particles &gt; 2.0 microm are more likely to impact in the upper tracheobronchial regions of the lung where mucociliary clearance is relatively rapid. Additionally, chromate emissions from spraying operations may be overestimated because larger particles, which are more easily trapped on an air filter, contain more chromate than the smaller particles, which are more likely to bypass an air filter."
1232150,Rehman and  Shakoori 2001,"Heavy metal resistance Chlorella spp., isolated from tannery effluents, and their role in remediation of hexavalent chromium in industrial waste water",,"Heavy metal resistance Chlorella spp., isolated from tannery effluents, and their role in remediation of hexavalent chromium in industrial waste water Abs: "
1232149,Teh et al. 2000,Sublethal effects of chromium-VI in the Asian clam (Potamocorbula amurensis),"Previously, we have shown that Asian clams (Potamocorbula amurensis) with highest metallic body burdens have highest prevalence of disease and lowest reproduction. The present study was designed to assess and validate potential sublethal toxicity of hexavalent chromium (Cr-VI) in clams under controlled laboratory exposure. For 7 days, three replicates of clam (n = 10 per replicate) were exposed to aqueous solution containing 0.00, 0.92, 8.40, or 25.6 mg l-1 of Cr-VI at 15 degrees C and 15 g l-1 salinity. Mortality reached 100% in the 25.6 mg l-1 group within 7 days. There was no significant difference in mortality among the control, 0.92, and 8.40 mg l-1 groups. Western blot analyses revealed significantly elevated stress protein hsp70 levels in the 8.40 mg l-1 treatment group. Histopathologic analyses revealed mild digestive gland (DG) atrophy in the control group. Clams exposed to 0.92 mg l-1 Cr-VI showed moderate DG atrophy, moderate granulomatous inflammation and necrosis in DG, ovary and testis. Lesions observed in the 8.40 mg l-1 treatment group included severe DG atrophy, severe granulomatous inflammation and necrosis in byssal gland, DG, gill, kidney, ovary and testis. In gills and testes of treated groups, apoptotic cells outnumbered mitotic cells. In addition, gills from clams in the 8.40 mg l-1 group showed enhanced hsp70 staining. Our studies support a cause-effect relationship between contaminants and reduced health in Asian clams and indicate the DGs, gills, and reproductive organs are principal targets of Cr-VI toxicity at sublethal concentrations. Results from this study suggest that Cr-VI may have played a role in the increased incidence of diseased clams seen in previous studies and these adverse effects may be working to decrease clam populations at sites with highest metallic contamination in the San Francisco Bay Estuary.","Sublethal effects of chromium-VI in the Asian clam (Potamocorbula amurensis) Abs: Previously, we have shown that Asian clams (Potamocorbula amurensis) with highest metallic body burdens have highest prevalence of disease and lowest reproduction. The present study was designed to assess and validate potential sublethal toxicity of hexavalent chromium (Cr-VI) in clams under controlled laboratory exposure. For 7 days, three replicates of clam (n = 10 per replicate) were exposed to aqueous solution containing 0.00, 0.92, 8.40, or 25.6 mg l-1 of Cr-VI at 15 degrees C and 15 g l-1 salinity. Mortality reached 100% in the 25.6 mg l-1 group within 7 days. There was no significant difference in mortality among the control, 0.92, and 8.40 mg l-1 groups. Western blot analyses revealed significantly elevated stress protein hsp70 levels in the 8.40 mg l-1 treatment group. Histopathologic analyses revealed mild digestive gland (DG) atrophy in the control group. Clams exposed to 0.92 mg l-1 Cr-VI showed moderate DG atrophy, moderate granulomatous inflammation and necrosis in DG, ovary and testis. Lesions observed in the 8.40 mg l-1 treatment group included severe DG atrophy, severe granulomatous inflammation and necrosis in byssal gland, DG, gill, kidney, ovary and testis. In gills and testes of treated groups, apoptotic cells outnumbered mitotic cells. In addition, gills from clams in the 8.40 mg l-1 group showed enhanced hsp70 staining. Our studies support a cause-effect relationship between contaminants and reduced health in Asian clams and indicate the DGs, gills, and reproductive organs are principal targets of Cr-VI toxicity at sublethal concentrations. Results from this study suggest that Cr-VI may have played a role in the increased incidence of diseased clams seen in previous studies and these adverse effects may be working to decrease clam populations at sites with highest metallic contamination in the San Francisco Bay Estuary."
1232148,Skowronski et al. 2001,Oral bioaccessibility of trivalent and hexavalent chromium in soil by simulated gastric fluid,"Chromium is found in soil from natural sources and anthropogenic activities. The ingestion of soil contaminated with chromium especially by children can have toxic consequences. Therefore, it is important to quantify the oral bioaccessibility of chromium in chromium in contaminated soil. In this study, chromium-51 as chromic (III) chloride and sodium chromate (VI), was mixed with an Atsion sandy soil and a Keyport clay soil and stored for 4 mo at either 21-25 degrees C or 2-4 degrees C. Utilizing simulated gastric conditions, the oral bioaccessibility of chromium in soil was determined. When the effects of soil on the bioaccessibility of chromium were compared, the data revealed the the bioaccessibility of chromium (III) from the clay soil was significantly lower than from the sandy at 21-25 degrees C. However, at 2-4 degrees C, more chromium (III) was extracted by synthetic gastric fluid from the clay soil than from the sandy soil. Temperature was also a factor as evidenced by the higher bioaccessibility of chromium (IV) in the sandy soil at 2-4 degrees C and of both chromium species in the clay soil at the same temperature. Reduction of the soluble chromium (VI) chemical to the nonsoluble chromium (III) compound in the acidic soils by naturally occurring organic matter in soil would explain the lower bioaccessibilty of chromium (VI) at 21-25 degrees C. At 2-4 degrees C, the data indicate that the rate of chromium (VI) reduction to chromium (III) was slowed. Although the results of this study are limited to one low concentration of chromium (III) and chromium (VI) and indicate that the bioaccessibility of chromium in soil can range between 18% and 72%, the data also suggest that there may be a potential health hazard from oral exposure to chromium in heavily contaminated sites. Therefore, more extensive research should be conducted to determine if thes findings can be extended to environmentally relevant concentrations.","Oral bioaccessibility of trivalent and hexavalent chromium in soil by simulated gastric fluid Abs: Chromium is found in soil from natural sources and anthropogenic activities. The ingestion of soil contaminated with chromium especially by children can have toxic consequences. Therefore, it is important to quantify the oral bioaccessibility of chromium in chromium in contaminated soil. In this study, chromium-51 as chromic (III) chloride and sodium chromate (VI), was mixed with an Atsion sandy soil and a Keyport clay soil and stored for 4 mo at either 21-25 degrees C or 2-4 degrees C. Utilizing simulated gastric conditions, the oral bioaccessibility of chromium in soil was determined. When the effects of soil on the bioaccessibility of chromium were compared, the data revealed the the bioaccessibility of chromium (III) from the clay soil was significantly lower than from the sandy at 21-25 degrees C. However, at 2-4 degrees C, more chromium (III) was extracted by synthetic gastric fluid from the clay soil than from the sandy soil. Temperature was also a factor as evidenced by the higher bioaccessibility of chromium (IV) in the sandy soil at 2-4 degrees C and of both chromium species in the clay soil at the same temperature. Reduction of the soluble chromium (VI) chemical to the nonsoluble chromium (III) compound in the acidic soils by naturally occurring organic matter in soil would explain the lower bioaccessibilty of chromium (VI) at 21-25 degrees C. At 2-4 degrees C, the data indicate that the rate of chromium (VI) reduction to chromium (III) was slowed. Although the results of this study are limited to one low concentration of chromium (III) and chromium (VI) and indicate that the bioaccessibility of chromium in soil can range between 18% and 72%, the data also suggest that there may be a potential health hazard from oral exposure to chromium in heavily contaminated sites. Therefore, more extensive research should be conducted to determine if thes findings can be extended to environmentally relevant concentrations."
1232147,Vasant et al. 2001,Apoptosis of lymphocytes in the presence of Cr(V) complexes: role in Cr(VI)-induced toxicity,"Cr(VI) compounds have been declared as a potent occupational carcinogen by IARC (1990) through epidemiological studies among workers in chrome plating, stainless-steel, and pigment industries. Studies relating to the role of intermediate oxidation states such as Cr(V) and Cr(IV) in Cr(VI)-induced carcinogenicity are gaining importance. In this study, issues relating to toxicity elicited by Cr(V) have been addressed and comparisons made with those relating to Cr(VI) employing human peripheral blood lymphocytes. Lymphocytes have been isolated from heparinized blood by Ficoll-Hypaque density gradient centrifugation and exposed to Cr(V) complexes viz. sodium bis(2-ethyl-2-hydroxybutyrato)oxochromate(V), Na[Cr(V)O(ehba)(2)], 1 and sodium bis(2-hydroxy-2-methylbutyrato)oxochromate(V), Na[Cr(V)O(hmba)(2)], 2 and Cr(VI). The phytohemagglutinin (PHA)-induced proliferation of lymphocytes has been found to be inhibited by the two complexes of Cr(V) and chromate Cr(VI) in a time- and concentration-dependent manner. Viability of cells decreases in the presence of Cr(V). Apoptosis appears to be the mode of cell death in the presence of both Cr(V) and Cr(VI). Pretreatment of cells with antioxidants before exposure to chromium(V) complexes reverse apoptosis partially. Possibility for the formation and implication of reactive oxygen species in Cr(V)-induced apoptosis of human lymphocyte cells has been indicated in this investigation. The intermediates of Cr(V) and radical species in the biotoxic pathways elicited by Cr(VI) seems feasible.","Apoptosis of lymphocytes in the presence of Cr(V) complexes: role in Cr(VI)-induced toxicity Abs: Cr(VI) compounds have been declared as a potent occupational carcinogen by IARC (1990) through epidemiological studies among workers in chrome plating, stainless-steel, and pigment industries. Studies relating to the role of intermediate oxidation states such as Cr(V) and Cr(IV) in Cr(VI)-induced carcinogenicity are gaining importance. In this study, issues relating to toxicity elicited by Cr(V) have been addressed and comparisons made with those relating to Cr(VI) employing human peripheral blood lymphocytes. Lymphocytes have been isolated from heparinized blood by Ficoll-Hypaque density gradient centrifugation and exposed to Cr(V) complexes viz. sodium bis(2-ethyl-2-hydroxybutyrato)oxochromate(V), Na[Cr(V)O(ehba)(2)], 1 and sodium bis(2-hydroxy-2-methylbutyrato)oxochromate(V), Na[Cr(V)O(hmba)(2)], 2 and Cr(VI). The phytohemagglutinin (PHA)-induced proliferation of lymphocytes has been found to be inhibited by the two complexes of Cr(V) and chromate Cr(VI) in a time- and concentration-dependent manner. Viability of cells decreases in the presence of Cr(V). Apoptosis appears to be the mode of cell death in the presence of both Cr(V) and Cr(VI). Pretreatment of cells with antioxidants before exposure to chromium(V) complexes reverse apoptosis partially. Possibility for the formation and implication of reactive oxygen species in Cr(V)-induced apoptosis of human lymphocyte cells has been indicated in this investigation. The intermediates of Cr(V) and radical species in the biotoxic pathways elicited by Cr(VI) seems feasible."
1232145,Miller et al. 2001,Chemical oxygen demand analysis of wastewater using trivalent manganese oxidant with chloride removal by sodium bismuthate pretreatment,"Current chemical oxygen demand (COD) analyses generate wastes containing hexavalent and trivalent chromium, mercury, and silver. Waste disposal is difficult, expensive, and poses environmental hazards. A new COD test is proposed that eliminates these metals and shortens analysis time, where trivalent manganese oxidant replaces hexavalent chromium (dichromate). A silver catalyst is not required. Optional pretreatment removes chloride via oxidation to chlorine using sodium bismuthate, eliminating the need for mercury. Sample aqueous and solid components are separated for chloride removal, then recombined for total COD measurement. Soluble and nonsoluble COD can be determined separately. Digestion at 150 degrees C is complete in 1 hour. Results are determined by titration or by spectrophotometric reading. Test wastes contain none of the metals regulated for disposal under the Resource Conservation and Recovery Act. Results are shown for selected organic compounds and various wastewaters. Statistical comparisons are made with dichromate COD and biochemical oxygen demand (BOD5) test values.","Chemical oxygen demand analysis of wastewater using trivalent manganese oxidant with chloride removal by sodium bismuthate pretreatment Abs: Current chemical oxygen demand (COD) analyses generate wastes containing hexavalent and trivalent chromium, mercury, and silver. Waste disposal is difficult, expensive, and poses environmental hazards. A new COD test is proposed that eliminates these metals and shortens analysis time, where trivalent manganese oxidant replaces hexavalent chromium (dichromate). A silver catalyst is not required. Optional pretreatment removes chloride via oxidation to chlorine using sodium bismuthate, eliminating the need for mercury. Sample aqueous and solid components are separated for chloride removal, then recombined for total COD measurement. Soluble and nonsoluble COD can be determined separately. Digestion at 150 degrees C is complete in 1 hour. Results are determined by titration or by spectrophotometric reading. Test wastes contain none of the metals regulated for disposal under the Resource Conservation and Recovery Act. Results are shown for selected organic compounds and various wastewaters. Statistical comparisons are made with dichromate COD and biochemical oxygen demand (BOD5) test values."
1232144,Sugden et al. 2001,"Direct oxidation of guanine and 7,8-dihydro-8-oxoguanine in DNA by a high-valent chromium complex: a possible mechanism for chromate genotoxicity","Intracellular reductive activation of the human carcinogen chromate, Cr(VI), is a necessary step in the formation of DNA lesions that lead to cancer. Reductive activation forms the transient metastable high-valent oxidation state of Cr(V) as a precursor to the final intracellularly stable oxidation state, Cr(III). In this study, we have used a model high-valent Cr(V) complex, N,N'-ethylenebis(salicylideneanimato)oxochromium(V), Cr(V)-Salen, to probe the mechanism of interaction between this oxidation state of chromium and DNA. This interaction was found to be specific toward the oxidation of the nucleic acid base guanine in unmodified single- and double-stranded oligonucleotides as measured by an increased level of DNA strand cleavage at these sites following piperidine treatment. Replacement of a single guanine residue in DNA with a more readily oxidized 7,8-dihydro-8-oxoguanine (8-oxo-G) base allowed for site-specific oxidation at this modified site within the DNA strand by the Cr(V)-Salen complex. HPLC and ESI-mass spectrometry were used to identify the modified guanine base lesions formed in the reaction of this high-valent chromium complex with the 8-oxo-G-containing DNA substrate. Two of these modified base lesions, identified as guanidinohydantoin and spiroiminodihydantoin, were found in the reaction of the Cr(V)-Salen complex with 8-oxo-G-modified DNA, while only one, spiroiminodihydantoin, was formed from oxidation of the 8-oxo-G nucleoside. A primer extension assay using the exo(-) Klenow fragment demonstrated polymerase arrest at the site of these base modifications as well as a high degree of misincorporation of adenine opposite the site of modification. These results suggest that mutations arising from G --&gt; T transversions would predominate with these lesions. The mechanism of damage and base oxidation products for the interaction between high-valent chromium and DNA described herein may be relevant to the in vivo formation of DNA damage leading to cancer in chromate-exposed human populations. These results also suggest how high-valent chromium can act as a cocarcinogen with 8-oxo-G-forming xenobiotics.","Direct oxidation of guanine and 7,8-dihydro-8-oxoguanine in DNA by a high-valent chromium complex: a possible mechanism for chromate genotoxicity Abs: Intracellular reductive activation of the human carcinogen chromate, Cr(VI), is a necessary step in the formation of DNA lesions that lead to cancer. Reductive activation forms the transient metastable high-valent oxidation state of Cr(V) as a precursor to the final intracellularly stable oxidation state, Cr(III). In this study, we have used a model high-valent Cr(V) complex, N,N'-ethylenebis(salicylideneanimato)oxochromium(V), Cr(V)-Salen, to probe the mechanism of interaction between this oxidation state of chromium and DNA. This interaction was found to be specific toward the oxidation of the nucleic acid base guanine in unmodified single- and double-stranded oligonucleotides as measured by an increased level of DNA strand cleavage at these sites following piperidine treatment. Replacement of a single guanine residue in DNA with a more readily oxidized 7,8-dihydro-8-oxoguanine (8-oxo-G) base allowed for site-specific oxidation at this modified site within the DNA strand by the Cr(V)-Salen complex. HPLC and ESI-mass spectrometry were used to identify the modified guanine base lesions formed in the reaction of this high-valent chromium complex with the 8-oxo-G-containing DNA substrate. Two of these modified base lesions, identified as guanidinohydantoin and spiroiminodihydantoin, were found in the reaction of the Cr(V)-Salen complex with 8-oxo-G-modified DNA, while only one, spiroiminodihydantoin, was formed from oxidation of the 8-oxo-G nucleoside. A primer extension assay using the exo(-) Klenow fragment demonstrated polymerase arrest at the site of these base modifications as well as a high degree of misincorporation of adenine opposite the site of modification. These results suggest that mutations arising from G --&gt; T transversions would predominate with these lesions. The mechanism of damage and base oxidation products for the interaction between high-valent chromium and DNA described herein may be relevant to the in vivo formation of DNA damage leading to cancer in chromate-exposed human populations. These results also suggest how high-valent chromium can act as a cocarcinogen with 8-oxo-G-forming xenobiotics."
1232141,Bagchi et al. 2001,"Chromium (VI)-induced oxidative stress, apoptotic cell death and modulation of p53 tumor suppressor gene","Chromium (VI) is a widely used industrial chemical, extensively used in paints, metal finishes, steel including stainless steel manufacturing, alloy cast irons, chrome, and wood treatment. On the contrary, chromium (III) salts such as chromium polynicotinate, chromium chloride and chromium picolinate, are used as micronutrients and nutritional supplements, and have been demonstrated to exhibit a significant number of health benefits in rodents and humans. However, the cause for the hexavalent chromium to induce cytotoxicity is not entirely understood. A series of in vitro and in vivo studies have demonstrated that chromium (VI) induces an oxidative stress through enhanced production of reactive oxygen species (ROS) leading to genomic DNA damage and oxidative deterioration of lipids and proteins. A cascade of cellular events occur following chromium (VI)-induced oxidative stress including enhanced production of superoxide anion and hydroxyl radicals, increased lipid peroxidation and genomic DNA fragmentation, modulation of intracellular oxidized states, activation of protein kinase C, apoptotic cell death and altered gene expression. In this paper, we have demonstrated concentration- and time-dependent effects of sodium dichromate (chromium (VI) or Cr (VI)) on enhanced production of superoxide anion and hydroxyl radicals, changes in intracellular oxidized states as determined by laser scanning confocal microscopy, DNA fragmentation and apoptotic cell death (by flow cytometry) in human peripheral blood mononuclear cells. These results were compared with the concentration-dependent effects of chromium (VI) on chronic myelogenous leukemic K562 cells and J774A.1 murine macrophage cells. Chromium (VI)-induced enhanced production of ROS, as well as oxidative tissue and DNA damage were observed in these cells. More pronounced effect was observed on chronic myelogenous leukemic K562 cells and J774A.1 murine macrophage cells. Furthermore, we have assessed the effect of a single oral LD50 dose of chromium (VI) on female C57BL/6Ntac and p53-deficient C57BL/6TSG p53 mice on enhanced production of superoxide anion, lipid peroxidation and DNA fragmentation in the hepatic and brain tissues. Chromium (VI)-induced more pronounced oxidative damage in p53 deficient mice. This in vivo study highlighted that apoptotic regulatory protein p53 may play a major role in chromium (VI)-induced oxidative stress and toxicity. Taken together, oxidative stress and oxidative tissue damage, and a cascade of cellular events including modulation of apoptotic regulatory gene p53 are involved in chromium (VI)-induced toxicity and carcinogenesis.","Chromium (VI)-induced oxidative stress, apoptotic cell death and modulation of p53 tumor suppressor gene Abs: Chromium (VI) is a widely used industrial chemical, extensively used in paints, metal finishes, steel including stainless steel manufacturing, alloy cast irons, chrome, and wood treatment. On the contrary, chromium (III) salts such as chromium polynicotinate, chromium chloride and chromium picolinate, are used as micronutrients and nutritional supplements, and have been demonstrated to exhibit a significant number of health benefits in rodents and humans. However, the cause for the hexavalent chromium to induce cytotoxicity is not entirely understood. A series of in vitro and in vivo studies have demonstrated that chromium (VI) induces an oxidative stress through enhanced production of reactive oxygen species (ROS) leading to genomic DNA damage and oxidative deterioration of lipids and proteins. A cascade of cellular events occur following chromium (VI)-induced oxidative stress including enhanced production of superoxide anion and hydroxyl radicals, increased lipid peroxidation and genomic DNA fragmentation, modulation of intracellular oxidized states, activation of protein kinase C, apoptotic cell death and altered gene expression. In this paper, we have demonstrated concentration- and time-dependent effects of sodium dichromate (chromium (VI) or Cr (VI)) on enhanced production of superoxide anion and hydroxyl radicals, changes in intracellular oxidized states as determined by laser scanning confocal microscopy, DNA fragmentation and apoptotic cell death (by flow cytometry) in human peripheral blood mononuclear cells. These results were compared with the concentration-dependent effects of chromium (VI) on chronic myelogenous leukemic K562 cells and J774A.1 murine macrophage cells. Chromium (VI)-induced enhanced production of ROS, as well as oxidative tissue and DNA damage were observed in these cells. More pronounced effect was observed on chronic myelogenous leukemic K562 cells and J774A.1 murine macrophage cells. Furthermore, we have assessed the effect of a single oral LD50 dose of chromium (VI) on female C57BL/6Ntac and p53-deficient C57BL/6TSG p53 mice on enhanced production of superoxide anion, lipid peroxidation and DNA fragmentation in the hepatic and brain tissues. Chromium (VI)-induced more pronounced oxidative damage in p53 deficient mice. This in vivo study highlighted that apoptotic regulatory protein p53 may play a major role in chromium (VI)-induced oxidative stress and toxicity. Taken together, oxidative stress and oxidative tissue damage, and a cascade of cellular events including modulation of apoptotic regulatory gene p53 are involved in chromium (VI)-induced toxicity and carcinogenesis."
1232140,Ye and  Shi 2001,Gene expression profile in response to chromium-induced cell stress in A549 cells,"Chromium (Cr) is a trace element required for life. Biological activities of Cr are complicated and remain to be fully investigated. It is known that the valence of Cr plays an important role in the biological activities of Cr. For example, Cr (VI) is classified as a metal carcinogen, but Cr (III) is widely used as a nutritional supplement. Establishment of a gene expression profile for Cr-induced cellular response is necessary to facilitate investigation of the biological activities of Cr. In the present study, a large-scale gene expression analysis was conducted using RNA of human lung epithelial cells after in vitro exposure to Cr (VI). Utilizing high-density oligonucleotide arrays representing 2400 genes, we observed that expression of 150 genes was up-regulated, and that of 70 genes were down-regulated by Cr (VI). Functional analysis of these responsive genes led to an outline of potential biological activities of Cr in six aspects. The gene expression profile reveals that Cr may involves in redox stress, calcium mobilization, energy metabolism, protein synthesis, cell cycle regulation and carcinogenesis in the cell. The results provide a critical clue for understanding molecular mechanisms of the biological activities of Cr.","Gene expression profile in response to chromium-induced cell stress in A549 cells Abs: Chromium (Cr) is a trace element required for life. Biological activities of Cr are complicated and remain to be fully investigated. It is known that the valence of Cr plays an important role in the biological activities of Cr. For example, Cr (VI) is classified as a metal carcinogen, but Cr (III) is widely used as a nutritional supplement. Establishment of a gene expression profile for Cr-induced cellular response is necessary to facilitate investigation of the biological activities of Cr. In the present study, a large-scale gene expression analysis was conducted using RNA of human lung epithelial cells after in vitro exposure to Cr (VI). Utilizing high-density oligonucleotide arrays representing 2400 genes, we observed that expression of 150 genes was up-regulated, and that of 70 genes were down-regulated by Cr (VI). Functional analysis of these responsive genes led to an outline of potential biological activities of Cr in six aspects. The gene expression profile reveals that Cr may involves in redox stress, calcium mobilization, energy metabolism, protein synthesis, cell cycle regulation and carcinogenesis in the cell. The results provide a critical clue for understanding molecular mechanisms of the biological activities of Cr."
1232139,Qian et al. 2001,Cr (VI) increases tyrosine phosphorylation through reactive oxygen species-mediated reactions,"While Cr (VI)-containing compounds are well established carcinogens, the mechanisms of their action remain to be investigated. In this study we show that Cr (VI) causes increased tyrosine phosphorylation in human lung epithelial A549 cells in a time-dependent manner. N-acetyl-cysteine (NAC), a general antioxidant, inhibited Cr (VI)-induced tyrosine phosphorylation. Catalase, a scavenger of H2O2, sodium formate and aspirin, scavengers of hydroxyl radical (*OH), also inhibited the increased tyrosine phosphorylation induced by Cr (VI). SOD, an inhibitor of superoxide radical (O2*-), caused less inhibition. ESR study shows that incubation of Cr (VI) with the A549 cells generates *OH radical. The generation of radical was decreased by addition of catalase and sodium formate, while SOD did not have any inhibitory effect. Oxygen consumption measurements show that addition of Cr (VI) to A549 cells resulted in enhanced molecular oxygen consumption. These results indicate that Cr (VI) can induce an increase in tyrosine phosphorylation. H2O2 and *OH radicals generated during the process are responsible for the increased tyrosine phosphorylation induced by Cr (VI).","Cr (VI) increases tyrosine phosphorylation through reactive oxygen species-mediated reactions Abs: While Cr (VI)-containing compounds are well established carcinogens, the mechanisms of their action remain to be investigated. In this study we show that Cr (VI) causes increased tyrosine phosphorylation in human lung epithelial A549 cells in a time-dependent manner. N-acetyl-cysteine (NAC), a general antioxidant, inhibited Cr (VI)-induced tyrosine phosphorylation. Catalase, a scavenger of H2O2, sodium formate and aspirin, scavengers of hydroxyl radical (*OH), also inhibited the increased tyrosine phosphorylation induced by Cr (VI). SOD, an inhibitor of superoxide radical (O2*-), caused less inhibition. ESR study shows that incubation of Cr (VI) with the A549 cells generates *OH radical. The generation of radical was decreased by addition of catalase and sodium formate, while SOD did not have any inhibitory effect. Oxygen consumption measurements show that addition of Cr (VI) to A549 cells resulted in enhanced molecular oxygen consumption. These results indicate that Cr (VI) can induce an increase in tyrosine phosphorylation. H2O2 and *OH radicals generated during the process are responsible for the increased tyrosine phosphorylation induced by Cr (VI)."
1232138,Krepkiy et al. 2001,Model reactions of Cr (VI) with DNA mediated by thiol species,"Model reactions were devised to investigate the capacity of physiologically interesting thiol compounds to mediate reactions between CrO4(2-) (Cr (VI)) and DNA. The sulfhydryl containing reagents included cysteine, glutathione, apo-metallothionein (apoMT). Zinc finger 3 of transcription factor IIIA (Zn-F3) of Xenopus laevis was investigated as a potential redox active site of reaction of Cr (VI) and thiol compounds. The DNA samples were calf thymus DNA and two oligomers, one of them specific for binding Zn-F3. Results showed that in the presence of Cr (VI) apoMT readily participated in damaging DNA in a reaction that appeared to be hydroxyl radical dependent. It also became cross-linked to oligomer and native DNA samples. In comparison, the other two thiol donors were largely inactive in these assays even though they, like apoMT, were able to reduce Cr (VI) to Cr (III) under the conditions of the experiments. Direct attempts to cross link thiols with DNA in the presence of Cr3+ were unsuccessful at pH 7.4. Together, the results indicate that apoMT can effectively collaborate with Cr (VI) in reactions that are deleterious to DNA.","Model reactions of Cr (VI) with DNA mediated by thiol species Abs: Model reactions were devised to investigate the capacity of physiologically interesting thiol compounds to mediate reactions between CrO4(2-) (Cr (VI)) and DNA. The sulfhydryl containing reagents included cysteine, glutathione, apo-metallothionein (apoMT). Zinc finger 3 of transcription factor IIIA (Zn-F3) of Xenopus laevis was investigated as a potential redox active site of reaction of Cr (VI) and thiol compounds. The DNA samples were calf thymus DNA and two oligomers, one of them specific for binding Zn-F3. Results showed that in the presence of Cr (VI) apoMT readily participated in damaging DNA in a reaction that appeared to be hydroxyl radical dependent. It also became cross-linked to oligomer and native DNA samples. In comparison, the other two thiol donors were largely inactive in these assays even though they, like apoMT, were able to reduce Cr (VI) to Cr (III) under the conditions of the experiments. Direct attempts to cross link thiols with DNA in the presence of Cr3+ were unsuccessful at pH 7.4. Together, the results indicate that apoMT can effectively collaborate with Cr (VI) in reactions that are deleterious to DNA."
1232137,Liu et al. 2001,On the mechanism of Cr (VI)-induced carcinogenesis: dose dependence of uptake and cellular responses,"Cr (VI) compounds are widely used industrial chemicals and are recognized human carcinogens. The mechanisms of carcinogenesis associated with these compounds remain to be investigated. The present study focused on dose-dependence of Cr (VI)-induced uptake and cellular responses. The results show that Cr (VI) is able to enter the cells (human lung epithelial cell line A549) at low concentration (&lt; 10 microM) and that the Cr (VI) uptake appears to be a combination of saturable transport and passive diffusion. Electron spin resonance (ESR) trapping measurements showed that upon stimulation with Cr (VI), A549 cells were able to generate reactive oxygen species (ROS). The amount of ROS generated depended on the Cr (VI) concentration. ROS generation involved NADPH-dependent flavoenzymes. Cr (VI) affected the following cellular parameters in a dose-dependent manner, (a) activation of nuclear transcription factors NF-kappaB, and p53, (b) DNA damage, (c) induction of cell apoptosis, and (d) inhibition of cell proliferation. The activation of transcription factors was assessed by electrophoretic mobility shift assay and western blot analysis, DNA damage by single cell gel electrophoresis assay, cell apoptosis by DNA fragmentation assay, and cell proliferation by a non-radioactive ELISA kit. At the concentration range used in the present study, no thresholds were found in all of these cell responses to Cr (VI). The results may guide further research to better understand and evaluate the risk of Cr (VI)-induced carcinogenesis at low levels of exposure.","On the mechanism of Cr (VI)-induced carcinogenesis: dose dependence of uptake and cellular responses Abs: Cr (VI) compounds are widely used industrial chemicals and are recognized human carcinogens. The mechanisms of carcinogenesis associated with these compounds remain to be investigated. The present study focused on dose-dependence of Cr (VI)-induced uptake and cellular responses. The results show that Cr (VI) is able to enter the cells (human lung epithelial cell line A549) at low concentration (&lt; 10 microM) and that the Cr (VI) uptake appears to be a combination of saturable transport and passive diffusion. Electron spin resonance (ESR) trapping measurements showed that upon stimulation with Cr (VI), A549 cells were able to generate reactive oxygen species (ROS). The amount of ROS generated depended on the Cr (VI) concentration. ROS generation involved NADPH-dependent flavoenzymes. Cr (VI) affected the following cellular parameters in a dose-dependent manner, (a) activation of nuclear transcription factors NF-kappaB, and p53, (b) DNA damage, (c) induction of cell apoptosis, and (d) inhibition of cell proliferation. The activation of transcription factors was assessed by electrophoretic mobility shift assay and western blot analysis, DNA damage by single cell gel electrophoresis assay, cell apoptosis by DNA fragmentation assay, and cell proliferation by a non-radioactive ELISA kit. At the concentration range used in the present study, no thresholds were found in all of these cell responses to Cr (VI). The results may guide further research to better understand and evaluate the risk of Cr (VI)-induced carcinogenesis at low levels of exposure."
1232136,Katz et al. 2001,Combining Drosophila melanogaster somatic-mutation-recombination and electron-spin-resonance-spectroscopy data to interpret epidemiologic observations on chromium carcinogenicity,"Lung cancers are significantly increased among workers exposed to chromate (Cr6+, Cr3+), chromium pigments (Cr6+) and chromium plating (Cr6+). Chromium lung burdens and cancer risk increase proportionately with duration of employment at long latencies. However, this epidemiologic information alone is insufficient in determining whether Cr6+ or Cr3+ are equally important in causing cancer. We have attempted to combine epidemiologic data with data from the Drosophila melanogaster somatic-mutation-recombination-test and from the in vitro electron-spin-resonance spectroscopy study to demonstrate that following somatic recombination plays a more important role than somatic mutation in chromium carcinogenesis. Cr4+ is more important than Cr5+ or Cr6+ in inducing somatic recombination while Cr6+ produces more and bigger clones than Cr4+ in somatic mutation. Cr3+ produces negative results in this fruit-fly wing-spot-assay. When the larvae and flies exposed to Cr6+ and Cr4+ are examined by ESR, only Cr5+ and Cr3+ are found. Thermodynamic parameters deltaE, deltaH, and deltaS are also estimated from these latter experiments to explain the relative importance of Cr6+, Cr4+, Cr3+ in chromium carcinogenesis among exposed industrial workers.","Combining Drosophila melanogaster somatic-mutation-recombination and electron-spin-resonance-spectroscopy data to interpret epidemiologic observations on chromium carcinogenicity Abs: Lung cancers are significantly increased among workers exposed to chromate (Cr6+, Cr3+), chromium pigments (Cr6+) and chromium plating (Cr6+). Chromium lung burdens and cancer risk increase proportionately with duration of employment at long latencies. However, this epidemiologic information alone is insufficient in determining whether Cr6+ or Cr3+ are equally important in causing cancer. We have attempted to combine epidemiologic data with data from the Drosophila melanogaster somatic-mutation-recombination-test and from the in vitro electron-spin-resonance spectroscopy study to demonstrate that following somatic recombination plays a more important role than somatic mutation in chromium carcinogenesis. Cr4+ is more important than Cr5+ or Cr6+ in inducing somatic recombination while Cr6+ produces more and bigger clones than Cr4+ in somatic mutation. Cr3+ produces negative results in this fruit-fly wing-spot-assay. When the larvae and flies exposed to Cr6+ and Cr4+ are examined by ESR, only Cr5+ and Cr3+ are found. Thermodynamic parameters deltaE, deltaH, and deltaS are also estimated from these latter experiments to explain the relative importance of Cr6+, Cr4+, Cr3+ in chromium carcinogenesis among exposed industrial workers."
1232135,Zhang et al. 2001,Cr (VI) induces cell growth arrest through hydrogen peroxide-mediated reactions,"Cr (VI) compounds are widely used in industries and are recognized human carcinogens. The mechanism of carcinogenesis associated with these compounds is not well understood. The present study focused on Cr (VI)-induced cell growth arrest in human lung epithelial A549 cells, using flow cytometric analysis of DNA content. Treatment of the cells with Cr (VI) at 1 microM caused a growth arrest at G2/M phase. An increase in Cr (VI) concentration enhanced the growth arrest. At a concentration of 25 microM, Cr (VI)-induced apoptosis became apparent. Superoxide dismutase (SOD) or sodium formate did not alter the Cr (VI)-induced cell growth arrest. While catalase inhibited growth, indicating H2O2 is an important mediator in Cr (VI)-induced G2/M phase arrest. Electron spin resonance (ESR) spin trapping measurements showed that incubation of cells with Cr (VI) generated hydroxyl radical (*OH). Catalase inhibited the *OH radical generation, indicating that H2O2 was generated from cells stimulated by Cr (VI), and that H2O2 functioned as a precursor for *OH radical generation. The formation of H2O2 from Cr (VI)-stimulated cells was also measured by the change in fluorescence of scopoletin in the presence of horseradish peroxidase. The mechanism of reactive oxygen species generation involved the reduction of molecular oxygen as shown by oxygen consumption assay. These results support the following conclusions: (a) Reactive oxygen species are generated in Cr (VI)-stimulated A549 cells through reduction of molecular oxygen, (b) Among the reactive oxygen species generated, H2O2 played a major role in causing G2/M phase arrest in human lung epithelial cells.","Cr (VI) induces cell growth arrest through hydrogen peroxide-mediated reactions Abs: Cr (VI) compounds are widely used in industries and are recognized human carcinogens. The mechanism of carcinogenesis associated with these compounds is not well understood. The present study focused on Cr (VI)-induced cell growth arrest in human lung epithelial A549 cells, using flow cytometric analysis of DNA content. Treatment of the cells with Cr (VI) at 1 microM caused a growth arrest at G2/M phase. An increase in Cr (VI) concentration enhanced the growth arrest. At a concentration of 25 microM, Cr (VI)-induced apoptosis became apparent. Superoxide dismutase (SOD) or sodium formate did not alter the Cr (VI)-induced cell growth arrest. While catalase inhibited growth, indicating H2O2 is an important mediator in Cr (VI)-induced G2/M phase arrest. Electron spin resonance (ESR) spin trapping measurements showed that incubation of cells with Cr (VI) generated hydroxyl radical (*OH). Catalase inhibited the *OH radical generation, indicating that H2O2 was generated from cells stimulated by Cr (VI), and that H2O2 functioned as a precursor for *OH radical generation. The formation of H2O2 from Cr (VI)-stimulated cells was also measured by the change in fluorescence of scopoletin in the presence of horseradish peroxidase. The mechanism of reactive oxygen species generation involved the reduction of molecular oxygen as shown by oxygen consumption assay. These results support the following conclusions: (a) Reactive oxygen species are generated in Cr (VI)-stimulated A549 cells through reduction of molecular oxygen, (b) Among the reactive oxygen species generated, H2O2 played a major role in causing G2/M phase arrest in human lung epithelial cells."
1232134,Chuang and  Yang 2001,Comparison of roles of three mitogen-activated protein kinases induced by chromium(VI) and cadmium in non-small-cell lung carcinoma cells,"Chromium(VI) [Cr(VI)] and cadmium (Cd) compounds are ubiquitous environmental carcinogens that have been associated with lung tumors and can induce apoptosis in various cell types. Three major mitogen-activation protein kinases (MAPKs), extracellular signal-regulated kinase (ERK), c-JUN N-terminal kinase (JNK) and p38, have been shown to regulate apoptosis. In this study we explore the abilities of Cr(VI) and Cd to activate JNK, p38 and ERK, including their roles in metal-mediated growth inhibition and apoptosis in a human non-small-cell lung carcinoma cell line, CL3. Exposure to K2Cr2O7 markedly activated JNK and p38 and moderately activated ERK in a dose- and time-dependent manner. The activated p38 decreased markedly and rapidly and the activated JNK decreased gradually when Cr(VI) was removed from media. At low cytotoxic doses, CdCl2 decreased ERK activity with concurrently transient activation of JNK, whereas at high cytotoxic doses it persistently activated all three MAPKs. The strength and duration of JNK and p38 activated by Cd were higher and longer than Cr(VI) did when compared at similar cytotoxic doses. In comparable experiment conditions Cd is a much stronger apoptotic inducer than Cr(VI) in CL3 cells. Cross-talk of MAPKs was observed in cells exposed to Cr(VI) but not Cd. Both metals could increase JNK activity through MKK7 but not MKK4. The Cd-activated JNK is involved in apoptosis, but the Cr-activated JNK is not. PD98059, an inhibitor of the ERK upstream activators MKK1/2, greatly enhanced the cytotoxicity and apoptosis of cells treated with low Cd doses. SB202190, an inhibitor of p38, decreased the cytotoxicity and apoptosis induced by high Cd doses. Conversely, neither SB202190 nor PD98059 altered Cr(VI)-induced cytotoxicity. The results suggest that JNK and p38 signals cooperatively participate in apoptosis induced by Cd and that the decreased ERK signal by low Cd doses contributes to growth inhibition or apoptosis. Oppositely, activation of ERK, JNK and p38 by Cr(VI) does not affect cytotoxicity.","Comparison of roles of three mitogen-activated protein kinases induced by chromium(VI) and cadmium in non-small-cell lung carcinoma cells Abs: Chromium(VI) [Cr(VI)] and cadmium (Cd) compounds are ubiquitous environmental carcinogens that have been associated with lung tumors and can induce apoptosis in various cell types. Three major mitogen-activation protein kinases (MAPKs), extracellular signal-regulated kinase (ERK), c-JUN N-terminal kinase (JNK) and p38, have been shown to regulate apoptosis. In this study we explore the abilities of Cr(VI) and Cd to activate JNK, p38 and ERK, including their roles in metal-mediated growth inhibition and apoptosis in a human non-small-cell lung carcinoma cell line, CL3. Exposure to K2Cr2O7 markedly activated JNK and p38 and moderately activated ERK in a dose- and time-dependent manner. The activated p38 decreased markedly and rapidly and the activated JNK decreased gradually when Cr(VI) was removed from media. At low cytotoxic doses, CdCl2 decreased ERK activity with concurrently transient activation of JNK, whereas at high cytotoxic doses it persistently activated all three MAPKs. The strength and duration of JNK and p38 activated by Cd were higher and longer than Cr(VI) did when compared at similar cytotoxic doses. In comparable experiment conditions Cd is a much stronger apoptotic inducer than Cr(VI) in CL3 cells. Cross-talk of MAPKs was observed in cells exposed to Cr(VI) but not Cd. Both metals could increase JNK activity through MKK7 but not MKK4. The Cd-activated JNK is involved in apoptosis, but the Cr-activated JNK is not. PD98059, an inhibitor of the ERK upstream activators MKK1/2, greatly enhanced the cytotoxicity and apoptosis of cells treated with low Cd doses. SB202190, an inhibitor of p38, decreased the cytotoxicity and apoptosis induced by high Cd doses. Conversely, neither SB202190 nor PD98059 altered Cr(VI)-induced cytotoxicity. The results suggest that JNK and p38 signals cooperatively participate in apoptosis induced by Cd and that the decreased ERK signal by low Cd doses contributes to growth inhibition or apoptosis. Oppositely, activation of ERK, JNK and p38 by Cr(VI) does not affect cytotoxicity."
1232133,Rock et al. 2001,"Hydrogen peroxide effects on chromium oxidation state and solubility in four diverse, chromium-enriched soils","High concentrations of H2O2 are being tested for in situ oxidation and remediation of buried organic contaminants in soils and groundwater. Peroxide is being considered as a direct chemical oxidant in Fenton-type reactions or as a source of oxidizing equivalents in bioremediation schemes. How H2O2 affects the oxidation state and solubility of Cr(III) and Cr(VI), common co-contaminants with organic chemicals, is explored here in four chemically diverse soils containing elevated levels of Cr. Soil contaminated with soluble Cr(VI) from chromite ore processing residue and soil containing high levels of recently reduced Cr (III) from electroplating waste both released dissolved Cr(VI) after single applications of up to 24 mM H2O2. In no case was there evidence that H202 reduced preexisting Cr(VI) to Cr(III), even though this would be allowed thermodynamically. Chromate in the leachates exceeded the U.S. EPA drinking water standard for total dissolved Cr (2 microM) by a factor of 10-1000. Anaerobic conditions in an organic-rich, tannery waste-contaminated soil protected Cr(III) from oxidation and mobilization. Mineral forms of Cr in serpentinitic soil near a former chromite mine also resisted oxidation on the time scale of days. Mobilization of Cr(VI) could be a hazardous consequence of using H2O2 for in situ remediation of chemically complex wastes, but H2O2 could prove attractive for ex situ treatment (i.e., soil washing). This paper demonstrates marked differences among Cr-contaminated soils in their capacity to release Cr(VI) upon chemical treatment with H2O2.","Hydrogen peroxide effects on chromium oxidation state and solubility in four diverse, chromium-enriched soils Abs: High concentrations of H2O2 are being tested for in situ oxidation and remediation of buried organic contaminants in soils and groundwater. Peroxide is being considered as a direct chemical oxidant in Fenton-type reactions or as a source of oxidizing equivalents in bioremediation schemes. How H2O2 affects the oxidation state and solubility of Cr(III) and Cr(VI), common co-contaminants with organic chemicals, is explored here in four chemically diverse soils containing elevated levels of Cr. Soil contaminated with soluble Cr(VI) from chromite ore processing residue and soil containing high levels of recently reduced Cr (III) from electroplating waste both released dissolved Cr(VI) after single applications of up to 24 mM H2O2. In no case was there evidence that H202 reduced preexisting Cr(VI) to Cr(III), even though this would be allowed thermodynamically. Chromate in the leachates exceeded the U.S. EPA drinking water standard for total dissolved Cr (2 microM) by a factor of 10-1000. Anaerobic conditions in an organic-rich, tannery waste-contaminated soil protected Cr(III) from oxidation and mobilization. Mineral forms of Cr in serpentinitic soil near a former chromite mine also resisted oxidation on the time scale of days. Mobilization of Cr(VI) could be a hazardous consequence of using H2O2 for in situ remediation of chemically complex wastes, but H2O2 could prove attractive for ex situ treatment (i.e., soil washing). This paper demonstrates marked differences among Cr-contaminated soils in their capacity to release Cr(VI) upon chemical treatment with H2O2."
1232132,Xie and  Zhuang 2001,"Chromium (VI)-induced production of reactive oxygen species, change of plasma membrane potential and dissipation of mitochondria membrane potential in Chinese hamster lung cell cultures","<strong>OBJECTIVE: </strong>To examine whether Reactive Oxygen Species (ROS) is generated, and whether plasma membrane potential and mitochondrial membrane potential are depolarized in Chinese Hamster Lung (CHL) cell lines exposed to Cr (VI).<br /><br /><strong>METHODS: </strong>CHL cells were incubated with Cr(VI) at 10 mumol/L, 2.5 mumol/L, 0.65 mumol/L for 3 and 6 hours, respectively. The production of ROS was performed by using 2,7-dichlorofluorescin diacetate; The changes in plasma membrane potential were estimated using fluorescent cationic dye DiBAC4; And the changes in mitochondria membrane potential were estimated using fluorescent dye Rhodamine 123.<br /><br /><strong>RESULTS: </strong>The ROS levels in CHL cells increased in all treated groups compared with the control group (P &lt; 0.01); The plasma membrane potential and mitochondrial membrane potential in CHL cells dissipated after incubated with Cr(VI) at 10 mumol/L for 3 hours and 6 hours (P &lt; 0.01), at 2.5 mumol/L for 6 hours (P &lt; 0.01 or 0.05).<br /><br /><strong>CONCLUSION: </strong>Cr(VI) causes the dissipation of plasma membrane potential and mitochondrial membrane potential in CHL cell cultures, and Cr(VI)-induced ROS may play a role in the injuries.","Chromium (VI)-induced production of reactive oxygen species, change of plasma membrane potential and dissipation of mitochondria membrane potential in Chinese hamster lung cell cultures Abs: <strong>OBJECTIVE: </strong>To examine whether Reactive Oxygen Species (ROS) is generated, and whether plasma membrane potential and mitochondrial membrane potential are depolarized in Chinese Hamster Lung (CHL) cell lines exposed to Cr (VI).<br /><br /><strong>METHODS: </strong>CHL cells were incubated with Cr(VI) at 10 mumol/L, 2.5 mumol/L, 0.65 mumol/L for 3 and 6 hours, respectively. The production of ROS was performed by using 2,7-dichlorofluorescin diacetate; The changes in plasma membrane potential were estimated using fluorescent cationic dye DiBAC4; And the changes in mitochondria membrane potential were estimated using fluorescent dye Rhodamine 123.<br /><br /><strong>RESULTS: </strong>The ROS levels in CHL cells increased in all treated groups compared with the control group (P &lt; 0.01); The plasma membrane potential and mitochondrial membrane potential in CHL cells dissipated after incubated with Cr(VI) at 10 mumol/L for 3 hours and 6 hours (P &lt; 0.01), at 2.5 mumol/L for 6 hours (P &lt; 0.01 or 0.05).<br /><br /><strong>CONCLUSION: </strong>Cr(VI) causes the dissipation of plasma membrane potential and mitochondrial membrane potential in CHL cell cultures, and Cr(VI)-induced ROS may play a role in the injuries."
1232131,Chen et al. 2002,Protective roles of NF-kappa B for chromium(VI)-induced cytotoxicity is revealed by expression of Ikappa B kinase-beta mutant,"To delineate the molecular mechanisms of NF-kappaB-mediated regulation of chromium(VI)-induced cell death, the signaling pathway leading to the activation of NF-kappaB was interrupted by stable transfection of a kinase-mutated form of IkappaB kinase beta (IKKbeta-KM). Here we demonstrate a novel role for the NF-kappaB transcription factor in inhibiting chromium(VI)-induced cell death. Inhibition of NF-kappaB by IKKbeta-KM or IKKbeta gene deficiency resulted in a spontaneous cleavage of Bcl-xL antiapoptotic protein due to the elevated caspase-3 activity. DNA microarray assay suggested a decreased expression of genes encoding antiapoptotic proteins, cIAP1 and cIAP2, in the cells overexpressing IKKbeta-KM. Chromium(VI) treatment of these NF-kappaB-inhibited cells induced necrotic-like cell death. Such chromium(VI)-induced cell killing could be partially inhibited by expression of exogenous cIAP1, an inhibitor of caspases, indicating that caspases along with others may be involved in chromium(VI)-induced cell death. These results suggest that NF-kappaB is essential for inhibiting toxic metal-induced cytotoxicity. Such inhibition may involve up-regulation of the expression of anti-death proteins including cIAP1 that prevents spontaneous caspase activation and subsequent cleavage of Bcl-xL protein.","Protective roles of NF-kappa B for chromium(VI)-induced cytotoxicity is revealed by expression of Ikappa B kinase-beta mutant Abs: To delineate the molecular mechanisms of NF-kappaB-mediated regulation of chromium(VI)-induced cell death, the signaling pathway leading to the activation of NF-kappaB was interrupted by stable transfection of a kinase-mutated form of IkappaB kinase beta (IKKbeta-KM). Here we demonstrate a novel role for the NF-kappaB transcription factor in inhibiting chromium(VI)-induced cell death. Inhibition of NF-kappaB by IKKbeta-KM or IKKbeta gene deficiency resulted in a spontaneous cleavage of Bcl-xL antiapoptotic protein due to the elevated caspase-3 activity. DNA microarray assay suggested a decreased expression of genes encoding antiapoptotic proteins, cIAP1 and cIAP2, in the cells overexpressing IKKbeta-KM. Chromium(VI) treatment of these NF-kappaB-inhibited cells induced necrotic-like cell death. Such chromium(VI)-induced cell killing could be partially inhibited by expression of exogenous cIAP1, an inhibitor of caspases, indicating that caspases along with others may be involved in chromium(VI)-induced cell death. These results suggest that NF-kappaB is essential for inhibiting toxic metal-induced cytotoxicity. Such inhibition may involve up-regulation of the expression of anti-death proteins including cIAP1 that prevents spontaneous caspase activation and subsequent cleavage of Bcl-xL protein."
1232130,Pourahmad and  O'Brien 2001,Biological reactive intermediates that mediate chromium (VI) toxicity,"1. Addition of Cr VI (dichromate) to isolated rat hepatocytes results in rapid glutathione oxidation, reactive oxygen species (ROS) formation, lipid peroxidation, decreased mitochondrial membrane potential and lysosomal membrane rupture before hepatocyte lysis occurred. 2. Cytotoxicity was prevented by ""ROS"" scavengers, antioxidants, and glutamine (ATP generator). Hepatocyte dichlorofluorescin oxidation (to determine ROS/Cr V formation) was inhibited by mannitol (a hydroxyl radical scavenger) or butylated hydroxyanisole and butylated hydroxytoluene (antioxidants). 3. The Cr VI reductive mechanism required for toxicity are not known. Cytotoxicity was also prevented by cytochrome P450 inhibitors, particularly CYP 2E1 inhibitors, but not inhibitors of DT diaphorase or glutathione reductase. This suggests that P450 reductase and/or reduced cytochrome P450 contributes to Cr VI reduction to Cr IV. 4. Glutathione depleted hepatocytes were resistant to Cr (VI) toxicity and much less dichlorofluorescin oxidation occurred. Reduction of dichromate by glutathione or cysteine in vitro was also accompanied by oxygen uptake and was inhibited by Mn II (a Cr IV reductant ). Cr VI induced cytotoxicity and ROS formation was also inhibited by Mn II which suggests that Cr IV and Cr IV.GSH mediate ""ROS"" formation in isolated hepatocytes. 5. In conclusion Cr VI cytotoxicity is associated with mitochondrial/lysosomal toxicity by the biological reactive intermediates Cr IV and ""ROS"".","Biological reactive intermediates that mediate chromium (VI) toxicity Abs: 1. Addition of Cr VI (dichromate) to isolated rat hepatocytes results in rapid glutathione oxidation, reactive oxygen species (ROS) formation, lipid peroxidation, decreased mitochondrial membrane potential and lysosomal membrane rupture before hepatocyte lysis occurred. 2. Cytotoxicity was prevented by ""ROS"" scavengers, antioxidants, and glutamine (ATP generator). Hepatocyte dichlorofluorescin oxidation (to determine ROS/Cr V formation) was inhibited by mannitol (a hydroxyl radical scavenger) or butylated hydroxyanisole and butylated hydroxytoluene (antioxidants). 3. The Cr VI reductive mechanism required for toxicity are not known. Cytotoxicity was also prevented by cytochrome P450 inhibitors, particularly CYP 2E1 inhibitors, but not inhibitors of DT diaphorase or glutathione reductase. This suggests that P450 reductase and/or reduced cytochrome P450 contributes to Cr VI reduction to Cr IV. 4. Glutathione depleted hepatocytes were resistant to Cr (VI) toxicity and much less dichlorofluorescin oxidation occurred. Reduction of dichromate by glutathione or cysteine in vitro was also accompanied by oxygen uptake and was inhibited by Mn II (a Cr IV reductant ). Cr VI induced cytotoxicity and ROS formation was also inhibited by Mn II which suggests that Cr IV and Cr IV.GSH mediate ""ROS"" formation in isolated hepatocytes. 5. In conclusion Cr VI cytotoxicity is associated with mitochondrial/lysosomal toxicity by the biological reactive intermediates Cr IV and ""ROS""."
1232129,Erdem et al. 2001,Cr(VI) reduction in aqueous solutions by using synthetic iron sulphide,"This study was carried out to reduce Cr(VI) in aqueous solutions by using synthetic iron sulphide. For that purpose, the effects of acid content, contact time, initial Cr(VI) concentration, temperature of the solution, particle size and dosage of iron sulphide on the Cr(VI) reduction were investigated. Reduction extent of Cr(VI) is, to a great extent, dependent on the amount of acid. The Cr(VI) in the solution containing two times the H2SO4 with respect to stoichiometric amount of Cr(VI) was completely reduced within 45 min by using 2.5 g litre(-1) iron sulphide at 25 degrees C. The reduction efficiency of Cr(VI) was increased with temperature of solution. The variation in particle size of iron sulphide did not affect the reduction yield of Cr(VI). The total reduction capacity of synthetic iron sulphide was found to be 237.6 mg Cr(VI) g(-1). The results related to shrinking particle model showed that the reduction reaction was chemically controlled and activation energy for theprocess was calculated as 38.4 kJ mol(-1).","Cr(VI) reduction in aqueous solutions by using synthetic iron sulphide Abs: This study was carried out to reduce Cr(VI) in aqueous solutions by using synthetic iron sulphide. For that purpose, the effects of acid content, contact time, initial Cr(VI) concentration, temperature of the solution, particle size and dosage of iron sulphide on the Cr(VI) reduction were investigated. Reduction extent of Cr(VI) is, to a great extent, dependent on the amount of acid. The Cr(VI) in the solution containing two times the H2SO4 with respect to stoichiometric amount of Cr(VI) was completely reduced within 45 min by using 2.5 g litre(-1) iron sulphide at 25 degrees C. The reduction efficiency of Cr(VI) was increased with temperature of solution. The variation in particle size of iron sulphide did not affect the reduction yield of Cr(VI). The total reduction capacity of synthetic iron sulphide was found to be 237.6 mg Cr(VI) g(-1). The results related to shrinking particle model showed that the reduction reaction was chemically controlled and activation energy for theprocess was calculated as 38.4 kJ mol(-1)."
1232128,Dubey et al. 2001,"Chromium (VI) in waters in parts of Sukinda chromite valley and health hazards, Orissa, India",,"Chromium (VI) in waters in parts of Sukinda chromite valley and health hazards, Orissa, India Abs: "
1232127,Gupta et al. 2001,Biosorption of chromium(VI) from aqueous solutions by green algae Spirogyra species,"Biosorption of heavy metals is an effective technology for the treatment of industrial wastewaters. Results are presented showing the sorption of Cr(VI) from solutions by biomass of filamentous algae Spirogyra species. Batch experiments were conducted to determine the adsorption properties of the biomass and it was observed that the adsorption capacity of the biomass strongly depends on equilibrium pH. Equilibrium isotherms were also obtained and maximum removal of Cr(VI) was around 14.7 x 10(3) mg metal, kg of dry weight biomass at a pH of 2.0 in 120 min with 5 mg/l of initial concentration. The results indicated that the biomass of Spirogyra species is suitable for the development of efficient biosorbent for the removal and recovery of Cr(VI) from wastewater.","Biosorption of chromium(VI) from aqueous solutions by green algae Spirogyra species Abs: Biosorption of heavy metals is an effective technology for the treatment of industrial wastewaters. Results are presented showing the sorption of Cr(VI) from solutions by biomass of filamentous algae Spirogyra species. Batch experiments were conducted to determine the adsorption properties of the biomass and it was observed that the adsorption capacity of the biomass strongly depends on equilibrium pH. Equilibrium isotherms were also obtained and maximum removal of Cr(VI) was around 14.7 x 10(3) mg metal, kg of dry weight biomass at a pH of 2.0 in 120 min with 5 mg/l of initial concentration. The results indicated that the biomass of Spirogyra species is suitable for the development of efficient biosorbent for the removal and recovery of Cr(VI) from wastewater."
1232126,Benova et al. 2002,Cytogenetic effects of hexavalent chromium in Bulgarian chromium platers,"The aim of the present study was to evaluate the genotoxic effects of hexavalent chromium (Cr(VI)) in vivo in exposed Bulgarian chromium platers by using classical cytogenetic and molecular cytogenetic analyses of peripheral lymphocytes and exfoliated buccal cells. No significant difference was observed between the exposed workers and the controls with regard to the frequency of cells with chromosome aberrations (CAs) using conventional Giemsa staining and in the frequency of sister chromatid exchanges (SCEs). However, there was a significant increase in the number of cells with micronuclei (MN) in peripheral lymphocytes from chromium exposed workers as compared to the controls. In the buccal cells from these workers, this increase was even more pronounced. Cytosine arabinoside (AraC), an inhibitor of DNA synthesis and repair, was found to significantly increase the levels of MN in vitro in the lymphocytes of both groups. The increase was more expressed in the lymphocytes of chromium exposed workers. Both centromere positive (C(+)) as well as centromere negative (C(-)) MN were observed by the fluorescence in situ hybridization (FISH) technique in both of the cell types studied. No difference between C(+) and C(-) MN frequencies was found in the lymphocytes as well as in the buccal cells. Thus, Cr(VI) appears to have both clastogenic as well as aneugenic effects in humans.","Cytogenetic effects of hexavalent chromium in Bulgarian chromium platers Abs: The aim of the present study was to evaluate the genotoxic effects of hexavalent chromium (Cr(VI)) in vivo in exposed Bulgarian chromium platers by using classical cytogenetic and molecular cytogenetic analyses of peripheral lymphocytes and exfoliated buccal cells. No significant difference was observed between the exposed workers and the controls with regard to the frequency of cells with chromosome aberrations (CAs) using conventional Giemsa staining and in the frequency of sister chromatid exchanges (SCEs). However, there was a significant increase in the number of cells with micronuclei (MN) in peripheral lymphocytes from chromium exposed workers as compared to the controls. In the buccal cells from these workers, this increase was even more pronounced. Cytosine arabinoside (AraC), an inhibitor of DNA synthesis and repair, was found to significantly increase the levels of MN in vitro in the lymphocytes of both groups. The increase was more expressed in the lymphocytes of chromium exposed workers. Both centromere positive (C(+)) as well as centromere negative (C(-)) MN were observed by the fluorescence in situ hybridization (FISH) technique in both of the cell types studied. No difference between C(+) and C(-) MN frequencies was found in the lymphocytes as well as in the buccal cells. Thus, Cr(VI) appears to have both clastogenic as well as aneugenic effects in humans."
1232125,Yurkow et al. 2002,Photochemical reduction of hexavalent chromium in glycerol-containing solutions,"Hexavalent chromium [Cr(VI)] in the form of potassium dichromate was photochemically reduced to trivalent chromium [Cr(III)] in aqueous solutions containing glycerol. This reaction occurred rapidly during irradiation with either unfiltered sunlight or a UVA-emitting light source. Photochemical reduction of Cr(VI) was pH-dependent and did not occur in dilute solutions of sodium hydroxide. In acidified solutions, the reduction occurred at elevated rates and at lower concentrations of glycerol. This reaction was found to be dependent on the unsubstituted alcohol groups of glycerol since alpha-phosphoglycerol and beta-phosphoglycerol did not support the photochemical reduction of Cr(VI). These findings suggest that glycerol or related polyols can be used for the remediation of hexavalent (toxic) chromium at contaminated environmental sites.","Photochemical reduction of hexavalent chromium in glycerol-containing solutions Abs: Hexavalent chromium [Cr(VI)] in the form of potassium dichromate was photochemically reduced to trivalent chromium [Cr(III)] in aqueous solutions containing glycerol. This reaction occurred rapidly during irradiation with either unfiltered sunlight or a UVA-emitting light source. Photochemical reduction of Cr(VI) was pH-dependent and did not occur in dilute solutions of sodium hydroxide. In acidified solutions, the reduction occurred at elevated rates and at lower concentrations of glycerol. This reaction was found to be dependent on the unsubstituted alcohol groups of glycerol since alpha-phosphoglycerol and beta-phosphoglycerol did not support the photochemical reduction of Cr(VI). These findings suggest that glycerol or related polyols can be used for the remediation of hexavalent (toxic) chromium at contaminated environmental sites."
1232121,Ellis et al. 2002,Chromium isotopes and the fate of hexavalent chromium in the environment,"Measurements of chromium (Cr) stable-isotope fractionation in laboratory experiments and natural waters show that lighter isotopes reacted preferentially during Cr(VI) reduction by magnetite and sediments. The 53Cr/52Cr ratio of the product was 3.4 +/- 0.1 per mil less than that of the reactant. 53Cr/52Cr shifts in water samples indicate the extent of reduction, a critical process that renders toxic Cr(VI) in the environment immobile and less toxic.","Chromium isotopes and the fate of hexavalent chromium in the environment Abs: Measurements of chromium (Cr) stable-isotope fractionation in laboratory experiments and natural waters show that lighter isotopes reacted preferentially during Cr(VI) reduction by magnetite and sediments. The 53Cr/52Cr ratio of the product was 3.4 +/- 0.1 per mil less than that of the reactant. 53Cr/52Cr shifts in water samples indicate the extent of reduction, a critical process that renders toxic Cr(VI) in the environment immobile and less toxic."
1232119,Flores-Tena and  Martínez-Tabchet 2001,The effect of chromium on the hemoglobin concentration of Limnodrilus hoffmeisteri (Oligochaeta: Tubificidae),"The purpose of this study was to determine the toxic effects of polluted sediments, mainly chromium, the El Niagara reservoir (Aguascalientes, Mexico) on a benthic oligochaete species. Acute toxicity tests with hexavalent chromium in an artificial sediment-water system resulted in 24-, 48-, and 96-h LC50 values of 49.53, 22.81, and 5.11 mg available chromium/kg dry sediment, respectivley, in Limnodrilus hoffmeisteri. The uptake of chromium by tubificids from artificial and polluted reservoir sediments was found to increase with metal concentration in sediments and exposure time. The increase was higher in experiments with artificial sediment. Cr concentration in worms was related to hemoglobin content, which decreased significantly when Cr concentrations were above 1.0 microg/g dry weight. Bioavailable chromium in the El Niágara reservoir sediments may be an important factor limiting the benthic species in this ecosystem.","The effect of chromium on the hemoglobin concentration of Limnodrilus hoffmeisteri (Oligochaeta: Tubificidae) Abs: The purpose of this study was to determine the toxic effects of polluted sediments, mainly chromium, the El Niagara reservoir (Aguascalientes, Mexico) on a benthic oligochaete species. Acute toxicity tests with hexavalent chromium in an artificial sediment-water system resulted in 24-, 48-, and 96-h LC50 values of 49.53, 22.81, and 5.11 mg available chromium/kg dry sediment, respectivley, in Limnodrilus hoffmeisteri. The uptake of chromium by tubificids from artificial and polluted reservoir sediments was found to increase with metal concentration in sediments and exposure time. The increase was higher in experiments with artificial sediment. Cr concentration in worms was related to hemoglobin content, which decreased significantly when Cr concentrations were above 1.0 microg/g dry weight. Bioavailable chromium in the El Niágara reservoir sediments may be an important factor limiting the benthic species in this ecosystem."
1232118,Pettine et al. 2002,Reduction of hexavalent chromium by H2O2 in acidic solutions,"The rates of the reduction of Cr(VI) with H2O2 were measured in NaCl solutions as a function of pH (1.5-4.8), temperature (5-40 degrees C), and ionic strength (I = 0.01-2 M) in the presence of an excess of reductant. The rate of Cr(VI) reduction is described by the general expression -d[Cr(VI)]/dt = k2[Cr(VI)](m)[H2O2](n)[H+](z), where m = 1 and n and z are two interdependent variables. The value of n is a function of pH between 2 and 4 (n = (3 x 10(a))/(1 + 10(a)), where a = -0.25 - 0.58pH + 0.26pH2) leveling off at pH &lt; 2 (where n approximately = 1) and pH &gt; 4 (where n approximately = 3). The rates of Cr(VI) reduction are acid-catalyzed, and the kinetic order z varies from about 1.8-0.5 with increasing H2O2 concentration, according to the equation z = 1.85 - 350.1H2O2 (M) which is valid for [H2O2] &lt; 0.004 M. The values of k2 (M(-(n+z)) min(-1)) are given by k2 = k/[H+](z) = k1/[H2O2](n)[H+](z), where k is the overall rate constant (M(-n) min(-1)) and k, is the pseudo-first-order rate constant (min(-1)). The values of k in the pH range 2-4 have been fitted to the equation log k = 2.14pH - 2.81 with sigma = +/- 0.18. The values of k2 are dependent on pH as well. Most of the results with H2O2 &lt; 3 mM are described by log k2 = 2.87pH - 0.55 with sigma = +/- 0.54. Experimental results suggest that the reduction of Cr(VI) to Cr(III) is controlled by the formation of Cr(V) intermediates. Values of k2 and k calculated from the above equations can be used to evaluate the rates of the reaction in acidic solutions under a wide range of experimental conditions, because the rates are independent of ionic strength, temperature, major ions, and micromolar levels of trace metals (Cu2+, Ni2+, Pb2+). The application of this rate law to environmental conditions suggests that this reaction may have a role in acidic solutions (aerosols and fog droplets) in the presence of high micromolar concentrations of H2O2.","Reduction of hexavalent chromium by H2O2 in acidic solutions Abs: The rates of the reduction of Cr(VI) with H2O2 were measured in NaCl solutions as a function of pH (1.5-4.8), temperature (5-40 degrees C), and ionic strength (I = 0.01-2 M) in the presence of an excess of reductant. The rate of Cr(VI) reduction is described by the general expression -d[Cr(VI)]/dt = k2[Cr(VI)](m)[H2O2](n)[H+](z), where m = 1 and n and z are two interdependent variables. The value of n is a function of pH between 2 and 4 (n = (3 x 10(a))/(1 + 10(a)), where a = -0.25 - 0.58pH + 0.26pH2) leveling off at pH &lt; 2 (where n approximately = 1) and pH &gt; 4 (where n approximately = 3). The rates of Cr(VI) reduction are acid-catalyzed, and the kinetic order z varies from about 1.8-0.5 with increasing H2O2 concentration, according to the equation z = 1.85 - 350.1H2O2 (M) which is valid for [H2O2] &lt; 0.004 M. The values of k2 (M(-(n+z)) min(-1)) are given by k2 = k/[H+](z) = k1/[H2O2](n)[H+](z), where k is the overall rate constant (M(-n) min(-1)) and k, is the pseudo-first-order rate constant (min(-1)). The values of k in the pH range 2-4 have been fitted to the equation log k = 2.14pH - 2.81 with sigma = +/- 0.18. The values of k2 are dependent on pH as well. Most of the results with H2O2 &lt; 3 mM are described by log k2 = 2.87pH - 0.55 with sigma = +/- 0.54. Experimental results suggest that the reduction of Cr(VI) to Cr(III) is controlled by the formation of Cr(V) intermediates. Values of k2 and k calculated from the above equations can be used to evaluate the rates of the reaction in acidic solutions under a wide range of experimental conditions, because the rates are independent of ionic strength, temperature, major ions, and micromolar levels of trace metals (Cu2+, Ni2+, Pb2+). The application of this rate law to environmental conditions suggests that this reaction may have a role in acidic solutions (aerosols and fog droplets) in the presence of high micromolar concentrations of H2O2."
1232117,Singh and  Singh 2002,Cr(VI) removal in acidic aqueous solution using iron-bearing industrial solid wastes and their stabilisation with cement,"In this study, iron-bearing industrial solid wastes iron filings, ETP sludge of steel and red mud of aluminium industries; were used for Cr(VI) removal at pH 3. A complete removal of Cr(VI) was found for initial 10 mg 1(-1) of 100 ml solutions in the presence of 2.5 g iron filings, 8 g ETP sludge and 10 g red mud for up to one hour of shaking at room temperature. After Cr(VI) removal, inclusion of chromium on the reacted iron filing surface was demonstrated by EDAX analysis. Leachability of chromium and iron from the reacted wastes was determined by using Toxicity Characteristics Leaching Procedure (TCLP). This test showed a very low level of leachability of chromium as Cr(III) and iron from the reacted wastes. To minimise their leachability further, Cr(VI)-reacted solid wastes were stabilised with Portland cement in their 3:1 ratio. Leachability tests of stabilised wastes by TCLP indicated a considerable decrease in leachability of chromium and iron compared with the that of reacted wastes alone. To explore the possibility of utilisation in building materials, bricks of cement-mixed Cr(VI)-reacted wastes were made and their comprehensive strength, durability and leachability under immersion conditions were measured.","Cr(VI) removal in acidic aqueous solution using iron-bearing industrial solid wastes and their stabilisation with cement Abs: In this study, iron-bearing industrial solid wastes iron filings, ETP sludge of steel and red mud of aluminium industries; were used for Cr(VI) removal at pH 3. A complete removal of Cr(VI) was found for initial 10 mg 1(-1) of 100 ml solutions in the presence of 2.5 g iron filings, 8 g ETP sludge and 10 g red mud for up to one hour of shaking at room temperature. After Cr(VI) removal, inclusion of chromium on the reacted iron filing surface was demonstrated by EDAX analysis. Leachability of chromium and iron from the reacted wastes was determined by using Toxicity Characteristics Leaching Procedure (TCLP). This test showed a very low level of leachability of chromium as Cr(III) and iron from the reacted wastes. To minimise their leachability further, Cr(VI)-reacted solid wastes were stabilised with Portland cement in their 3:1 ratio. Leachability tests of stabilised wastes by TCLP indicated a considerable decrease in leachability of chromium and iron compared with the that of reacted wastes alone. To explore the possibility of utilisation in building materials, bricks of cement-mixed Cr(VI)-reacted wastes were made and their comprehensive strength, durability and leachability under immersion conditions were measured."
1232116,Viamajala et al. 2002,Chromate reduction in Shewanella oneidensis MR-1 is an inducible process associated with anaerobic growth,"Cr(VI) reduction was observed during tests with Shewanella oneidensis MR-1 (previously named S. putrefaciens MR-1) while being grown with nitrate or fumarate as electron acceptor and lactate as electron donor. From the onset of anoxic growth on fumarate, we measured a gradual and progressive increase in the specific Cr(VI) reduction rate with incubation time until a maximum was reached at late exponential/early stationary phase. Under denitrifying conditions, the specific Cr(VI) reduction rate was inhibited by nitrite, which is produced during nitrate reduction. However, once nitrite was consumed, the specific reduction rate increased until a maximum was reached, again during the late exponential/early stationary phase. Thus, under both fumarate- and nitrate-reducing conditions, an increase in the specific Cr(VI) reduction rate was observed as the microorganisms transition from oxic to anoxic growth conditions, presumably as a result of induction of enzyme systems capable of reducing Cr(VI). Although Cr(VI) reduction has been studied in MR-1 and in other facultative bacteria under both oxic and anoxic conditions, a transition in specific reduction rates based on physiological conditions during growth is a novel finding. Such physiological responses provide information required for optimizing the operation of in situ systems for remediating groundwater contaminated with heavy metals and radionuclides, especially those that are characterized by temporal variations in oxygen content. Moreover, such information may point the way to a better understanding of the cellular processes used by soil bacteria to accomplish Cr(VI) reduction.","Chromate reduction in Shewanella oneidensis MR-1 is an inducible process associated with anaerobic growth Abs: Cr(VI) reduction was observed during tests with Shewanella oneidensis MR-1 (previously named S. putrefaciens MR-1) while being grown with nitrate or fumarate as electron acceptor and lactate as electron donor. From the onset of anoxic growth on fumarate, we measured a gradual and progressive increase in the specific Cr(VI) reduction rate with incubation time until a maximum was reached at late exponential/early stationary phase. Under denitrifying conditions, the specific Cr(VI) reduction rate was inhibited by nitrite, which is produced during nitrate reduction. However, once nitrite was consumed, the specific reduction rate increased until a maximum was reached, again during the late exponential/early stationary phase. Thus, under both fumarate- and nitrate-reducing conditions, an increase in the specific Cr(VI) reduction rate was observed as the microorganisms transition from oxic to anoxic growth conditions, presumably as a result of induction of enzyme systems capable of reducing Cr(VI). Although Cr(VI) reduction has been studied in MR-1 and in other facultative bacteria under both oxic and anoxic conditions, a transition in specific reduction rates based on physiological conditions during growth is a novel finding. Such physiological responses provide information required for optimizing the operation of in situ systems for remediating groundwater contaminated with heavy metals and radionuclides, especially those that are characterized by temporal variations in oxygen content. Moreover, such information may point the way to a better understanding of the cellular processes used by soil bacteria to accomplish Cr(VI) reduction."
1232115,Daulton et al. 2002,Electron energy loss spectroscopy techniques for the study of microbial chromium(VI) reduction,"Electron energy loss spectroscopy (EELS) techniques were used to determine oxidation state, at high spatial resolution, of chromium associated with the metal-reducing bacteria, Shewanella oneidensis, in anaerobic cultures containing Cr(VI)O4(2-). These techniques were applied to fixed cells examined in thin section by conventional transmission electron microscopy (TEM) as well as unfixed, hydrated bacteria examined by environmental cell (EC)-TEM. Two distinct populations of bacteria were observed by TEM: bacteria exhibiting low image contrast and bacteria exhibiting high contrast in their cell membrane (or boundary) structure which was often encrusted with high-contrast precipitates. Measurements by EELS demonstrated that cell boundaries became saturated with low concentrations of Cr and the precipitates encrusting bacterial cells contained a reduced form of Cr in oxidation state + 3 or lower.","Electron energy loss spectroscopy techniques for the study of microbial chromium(VI) reduction Abs: Electron energy loss spectroscopy (EELS) techniques were used to determine oxidation state, at high spatial resolution, of chromium associated with the metal-reducing bacteria, Shewanella oneidensis, in anaerobic cultures containing Cr(VI)O4(2-). These techniques were applied to fixed cells examined in thin section by conventional transmission electron microscopy (TEM) as well as unfixed, hydrated bacteria examined by environmental cell (EC)-TEM. Two distinct populations of bacteria were observed by TEM: bacteria exhibiting low image contrast and bacteria exhibiting high contrast in their cell membrane (or boundary) structure which was often encrusted with high-contrast precipitates. Measurements by EELS demonstrated that cell boundaries became saturated with low concentrations of Cr and the precipitates encrusting bacterial cells contained a reduced form of Cr in oxidation state + 3 or lower."
1232114,Rao et al. 2002,Green route for the utilization of chrome shavings (chromium-containing solid waste) in tanning industry,"Chromium-containing wastes from various industrial sectors are under critical review. Leather processing is one such industrial activity that generates chromium-bearing wastes in different forms. One of them is chrome shavings, and this contributes to an extent of 10% of the quantum of raw skins/hides processed, amounting to 0.8 million ton globally. In this study, the high protein content of chrome shavings has been utilized for reduction of chromium(VI) in the preparation of chrome tanning agent. This approach has been exploited for the development of two products: one with chrome shavings alone as reducing agent and the other with equal proportion of chrome shavings and molasses. The developed products exhibit more masking due to the formation of intermediate organic oligopeptides. This has been corroborated through the spectral, hydrolysis, and species-wise distribution studies. The formation of these organic masking agents helps in chrome tanning by shifting the precipitation point of chromium to relatively higher pH levels. Hence, the developed products find use as chrome tanning agents for leather processing, thus providing a means for better utilization of chrome shaving wastes.","Green route for the utilization of chrome shavings (chromium-containing solid waste) in tanning industry Abs: Chromium-containing wastes from various industrial sectors are under critical review. Leather processing is one such industrial activity that generates chromium-bearing wastes in different forms. One of them is chrome shavings, and this contributes to an extent of 10% of the quantum of raw skins/hides processed, amounting to 0.8 million ton globally. In this study, the high protein content of chrome shavings has been utilized for reduction of chromium(VI) in the preparation of chrome tanning agent. This approach has been exploited for the development of two products: one with chrome shavings alone as reducing agent and the other with equal proportion of chrome shavings and molasses. The developed products exhibit more masking due to the formation of intermediate organic oligopeptides. This has been corroborated through the spectral, hydrolysis, and species-wise distribution studies. The formation of these organic masking agents helps in chrome tanning by shifting the precipitation point of chromium to relatively higher pH levels. Hence, the developed products find use as chrome tanning agents for leather processing, thus providing a means for better utilization of chrome shaving wastes."
1232113,Fernandes et al. 2002,Chromium(VI) interaction with plant and animal mitochondrial bioenergetics: a comparative study,"The mechanism of Cr(VI)-induced toxicity in plants and animals has been assessed for mitochondrial bioenergetics and membrane damage in turnip root and rat liver mitochondria. By using succinate as the respiratory substrate, ADP/O and respiratory control ratio (RCR) were depressed as a function of Cr(VI) concentration. State 3 and uncoupled respiration were also depressed by Cr(VI). Rat mitochondria revealed a higher sensitivity to Cr(VI), as compared to turnip mitochondria. Rat mitochondrial state 4 respiration rate triplicated in contrast to negligible stimulation of turnip state 4 respiration. Chromium(VI) inhibited the activity of the NADH-ubiquinone oxidoreductase (complex I) from rat liver mitochondria and succinate-dehydrogenases (complex II) from plant and animal mitochondria. In rat liver mitochondria, complex I was more sensitive to Cr(VI) than complex II. The activity of cytochrome c oxidase (complex IV) was not sensitive to Cr(VI). Unique for plant mitochondria, exogenous NADH uncoupled respiration was unaffected by Cr(VI), indicating that the NADH dehydrogenase of the outer leaflet of the plant inner membrane, in addition to complexes III and IV, were insensitive to Cr(VI). The ATPase activity (complex V) was stimulated in rat liver mitochondria, but inhibited in turnip root mitochondria. In both, turnip and rat mitochondria, Cr(VI) depressed mitochondrial succinate-dependent transmembrane potential (Deltapsi) and phosphorylation efficiency, but it neither affected mitochondrial membrane permeabilization to protons (H+) nor induced membrane lipid peroxidation. However, Cr(VI) induced mitochondrial membrane permeabilization to K+, an effect that was more pronounced in turnip root than in rat liver mitochondria. In conclusion, Cr(VI)-induced perturbations of mitochondrial bioenergetics compromises energy-dependent biochemical processes and, therefore, may contribute to the basal mechanism underlying its toxic effects in plant and animal cells.","Chromium(VI) interaction with plant and animal mitochondrial bioenergetics: a comparative study Abs: The mechanism of Cr(VI)-induced toxicity in plants and animals has been assessed for mitochondrial bioenergetics and membrane damage in turnip root and rat liver mitochondria. By using succinate as the respiratory substrate, ADP/O and respiratory control ratio (RCR) were depressed as a function of Cr(VI) concentration. State 3 and uncoupled respiration were also depressed by Cr(VI). Rat mitochondria revealed a higher sensitivity to Cr(VI), as compared to turnip mitochondria. Rat mitochondrial state 4 respiration rate triplicated in contrast to negligible stimulation of turnip state 4 respiration. Chromium(VI) inhibited the activity of the NADH-ubiquinone oxidoreductase (complex I) from rat liver mitochondria and succinate-dehydrogenases (complex II) from plant and animal mitochondria. In rat liver mitochondria, complex I was more sensitive to Cr(VI) than complex II. The activity of cytochrome c oxidase (complex IV) was not sensitive to Cr(VI). Unique for plant mitochondria, exogenous NADH uncoupled respiration was unaffected by Cr(VI), indicating that the NADH dehydrogenase of the outer leaflet of the plant inner membrane, in addition to complexes III and IV, were insensitive to Cr(VI). The ATPase activity (complex V) was stimulated in rat liver mitochondria, but inhibited in turnip root mitochondria. In both, turnip and rat mitochondria, Cr(VI) depressed mitochondrial succinate-dependent transmembrane potential (Deltapsi) and phosphorylation efficiency, but it neither affected mitochondrial membrane permeabilization to protons (H+) nor induced membrane lipid peroxidation. However, Cr(VI) induced mitochondrial membrane permeabilization to K+, an effect that was more pronounced in turnip root than in rat liver mitochondria. In conclusion, Cr(VI)-induced perturbations of mitochondrial bioenergetics compromises energy-dependent biochemical processes and, therefore, may contribute to the basal mechanism underlying its toxic effects in plant and animal cells."
1232112,Hwang et al. 2002,Effects of ferrous iron and molecular oxygen on chromium(VI) redox kinetics in the presence of aquifer solids,"The kinetics and stoichiometry of the reduction of hexavalent chromium (Cr(VI)) with ferrous iron (Fe(II)) were examined in systems with and without aquifer solids. Cr(VI) reduction was rapid in the absence of solids, but demonstrated slower and more complex kinetics in the presence of aquifer solids. The aquifer solids removed Fe(II) from solution and a portion of the reducing capacity of Fe(II) was transferred to the aquifer solids. The solid phases were then able to continue to remove Cr(VI). This suggests in situ treatment of Cr(VI) by Fe(II) injection would be feasible in the aquifer environment. In general, re-oxidation of reduced chromium by molecular oxygen was not observed in our systems over time periods of nearly 1 year, suggesting that the potential for chromium solubilization under these oxidizing conditions will be low. An empirical model was developed to describe the reduction kinetics of Cr(VI) in the presence of solids. The model assumes that the reaction is brought about by pseudo-species of iron that react instantaneously, rapidly and slowly with Cr(VI). A fourth pseudo-species is assumed to be non-reactive. Model coefficients were determined by non-linear regression. The model was able to describe observed concentrations of chromium well, but analysis of model errors indicated the potential existence of a distribution of species with different reaction rates rather than just three distinct species. Another model was developed to predict concentrations of different pseudo-species depending on the total amount of Fe(II) added and the amount of aquifer solids present. This model assumed that pseudo-species could result from intrinsic characteristics of the aquifer solids as well as being formed by addition of Fe(II), which could sorb to the aquifer solids.","Effects of ferrous iron and molecular oxygen on chromium(VI) redox kinetics in the presence of aquifer solids Abs: The kinetics and stoichiometry of the reduction of hexavalent chromium (Cr(VI)) with ferrous iron (Fe(II)) were examined in systems with and without aquifer solids. Cr(VI) reduction was rapid in the absence of solids, but demonstrated slower and more complex kinetics in the presence of aquifer solids. The aquifer solids removed Fe(II) from solution and a portion of the reducing capacity of Fe(II) was transferred to the aquifer solids. The solid phases were then able to continue to remove Cr(VI). This suggests in situ treatment of Cr(VI) by Fe(II) injection would be feasible in the aquifer environment. In general, re-oxidation of reduced chromium by molecular oxygen was not observed in our systems over time periods of nearly 1 year, suggesting that the potential for chromium solubilization under these oxidizing conditions will be low. An empirical model was developed to describe the reduction kinetics of Cr(VI) in the presence of solids. The model assumes that the reaction is brought about by pseudo-species of iron that react instantaneously, rapidly and slowly with Cr(VI). A fourth pseudo-species is assumed to be non-reactive. Model coefficients were determined by non-linear regression. The model was able to describe observed concentrations of chromium well, but analysis of model errors indicated the potential existence of a distribution of species with different reaction rates rather than just three distinct species. Another model was developed to predict concentrations of different pseudo-species depending on the total amount of Fe(II) added and the amount of aquifer solids present. This model assumed that pseudo-species could result from intrinsic characteristics of the aquifer solids as well as being formed by addition of Fe(II), which could sorb to the aquifer solids."
1232111,Farmer et al. 2002,Chromium speciation and fractionation in ground and surface waters in the vicinity of chromite ore processing residue disposal sites,"Chromium concentrations of up to 91 mg l(-1) were found by ICP-OES for ground water from nine boreholes at four landfill sites in an area of S.E. Glasgow/S. Lanarkshire where high-lime chromite ore processing residue (COPR) from a local chemical works had been deposited from 1830 to 1968. Surface water concentrations of up to 6.7 mg l(-1) in a local tributary stream fell to 0.11 mg l(-1) in the River Clyde. Two independent techniques of complexation/colorimetry and speciated isotope dilution mass spectrometry (SIDMS) showed that Cr was predominantly (&gt;90%) in hexavalent form (CrVI) as CrO4(2-), as anticipated at the high pH (7.5-12.5) of the sites. Some differences between the implied and directly determined concentrations of dissolved CrIII, however, appeared related to the total organic carbon (TOC) content. This was most significant for the ground water from one borehole that had the highest TOC concentration of 300 mg l(-1) and at which &lt; 3% of Cr was in the form of CrVI. Subsequent ultrafiltration produced significant decreases in Cr concentration with decreasing size fractions, e.g. &lt;0.45 microm, &lt; 100 kDa, &lt;30 kDa and &lt; 1 kDa by the tangential-flow method. As this appeared related more to concentrations of humic substances than of TOC per se, horizontal bed gel electrophoresis of freeze-dried ultrafilter retentates was carried out to further characterise the CrIII-organic complex. This showed for the main Cr-containing fraction, 100 kDa-0.45 microm, that the Cr was associated with a dark brown band characteristic of organic (humic) matter. Comparison of gel electrophoresis and FTIR results for ultrafilter retentates of ground water from this borehole with those for a borehole at another site where CrVI predominated suggested the influence of carboxylate groups, both in reducing CrVI and in forming soluble CrIII-humic complexes. The implications of this for remediation strategies (especially those based on the addition of organic matter) designed to reduce highly mobile and carcinogenic Cr(VI)O4(2-) to the much less harmful CrIII as insoluble Cr(OH)3 are discussed.","Chromium speciation and fractionation in ground and surface waters in the vicinity of chromite ore processing residue disposal sites Abs: Chromium concentrations of up to 91 mg l(-1) were found by ICP-OES for ground water from nine boreholes at four landfill sites in an area of S.E. Glasgow/S. Lanarkshire where high-lime chromite ore processing residue (COPR) from a local chemical works had been deposited from 1830 to 1968. Surface water concentrations of up to 6.7 mg l(-1) in a local tributary stream fell to 0.11 mg l(-1) in the River Clyde. Two independent techniques of complexation/colorimetry and speciated isotope dilution mass spectrometry (SIDMS) showed that Cr was predominantly (&gt;90%) in hexavalent form (CrVI) as CrO4(2-), as anticipated at the high pH (7.5-12.5) of the sites. Some differences between the implied and directly determined concentrations of dissolved CrIII, however, appeared related to the total organic carbon (TOC) content. This was most significant for the ground water from one borehole that had the highest TOC concentration of 300 mg l(-1) and at which &lt; 3% of Cr was in the form of CrVI. Subsequent ultrafiltration produced significant decreases in Cr concentration with decreasing size fractions, e.g. &lt;0.45 microm, &lt; 100 kDa, &lt;30 kDa and &lt; 1 kDa by the tangential-flow method. As this appeared related more to concentrations of humic substances than of TOC per se, horizontal bed gel electrophoresis of freeze-dried ultrafilter retentates was carried out to further characterise the CrIII-organic complex. This showed for the main Cr-containing fraction, 100 kDa-0.45 microm, that the Cr was associated with a dark brown band characteristic of organic (humic) matter. Comparison of gel electrophoresis and FTIR results for ultrafilter retentates of ground water from this borehole with those for a borehole at another site where CrVI predominated suggested the influence of carboxylate groups, both in reducing CrVI and in forming soluble CrIII-humic complexes. The implications of this for remediation strategies (especially those based on the addition of organic matter) designed to reduce highly mobile and carcinogenic Cr(VI)O4(2-) to the much less harmful CrIII as insoluble Cr(OH)3 are discussed."
1232110,Desjardin et al. 2002,Effect of microbial activity on the mobility of chromium in soils,"The effect of microbial activity on the chemical state of chromium, in a contaminated soil located in the Rh?ne-Alpes region (France), has been investigated. This soil contained 4,700 mg kg(-1) Cr, with about 40% present in the soluble hexavalent form. Indigenous microbial activity was found to significantly reduce Cr(VI) to the less mobile form (III) when the soil was incubated at 30 degrees C in an aqueous medium containing glucose and nutrients. A Cr(VI)-reducing strain of Streptomyces thermocarboxydus was isolated from the contaminated soil. The strain was found to metabolize Cr(VI) in a similar manner as an exogenous inoculum of Pseudomonas fluorescens LB300, and to precipitate chromium as a Cr oxyhydroxide with a gammaCrOOH-like local structure. The Cr(VI)-reducing activity of S. thermocarboxydus was induced, or significantly accelerated, by the aggregation of bacterial cells or their adhesion to suspended solid particles, and was stimulated in pure culture by glycerol and chromate.","Effect of microbial activity on the mobility of chromium in soils Abs: The effect of microbial activity on the chemical state of chromium, in a contaminated soil located in the Rh?ne-Alpes region (France), has been investigated. This soil contained 4,700 mg kg(-1) Cr, with about 40% present in the soluble hexavalent form. Indigenous microbial activity was found to significantly reduce Cr(VI) to the less mobile form (III) when the soil was incubated at 30 degrees C in an aqueous medium containing glucose and nutrients. A Cr(VI)-reducing strain of Streptomyces thermocarboxydus was isolated from the contaminated soil. The strain was found to metabolize Cr(VI) in a similar manner as an exogenous inoculum of Pseudomonas fluorescens LB300, and to precipitate chromium as a Cr oxyhydroxide with a gammaCrOOH-like local structure. The Cr(VI)-reducing activity of S. thermocarboxydus was induced, or significantly accelerated, by the aggregation of bacterial cells or their adhesion to suspended solid particles, and was stimulated in pure culture by glycerol and chromate."
1232109,Dennis et al. 2002,Control of exposure to hexavalent chromium and ozone in gas metal arc welding of stainless steels by use of a secondary shield gas,"Previous work has demonstrated that the shield gas composition in gas metal arc welding can have a considerable effect on hexavalent chromium [Cr(VI)] concentration in the fume and on ozone concentrations near the arc. Normally a single shield gas is used. This paper describes a double shroud torch that allows used of concentric shield gases of different compositions. A solid stainless steel wire was used for welding. The double shroud torch used secondary shield gases containing small amounts of the reducing agents NO and C2H4. The Cr(VI) concentration in the fume and ozone concentration at a fixed point relative to the arc were measured and compared with results when using a single shield gas. Use of the reducing agents in secondary shielding using the double shroud torch was found to offer advantages for ozone concentration reduction compared with use in a conventional torch, but this was not found to be an advantage for reducing Cr(VI) concentrations.","Control of exposure to hexavalent chromium and ozone in gas metal arc welding of stainless steels by use of a secondary shield gas Abs: Previous work has demonstrated that the shield gas composition in gas metal arc welding can have a considerable effect on hexavalent chromium [Cr(VI)] concentration in the fume and on ozone concentrations near the arc. Normally a single shield gas is used. This paper describes a double shroud torch that allows used of concentric shield gases of different compositions. A solid stainless steel wire was used for welding. The double shroud torch used secondary shield gases containing small amounts of the reducing agents NO and C2H4. The Cr(VI) concentration in the fume and ozone concentration at a fixed point relative to the arc were measured and compared with results when using a single shield gas. Use of the reducing agents in secondary shielding using the double shroud torch was found to offer advantages for ozone concentration reduction compared with use in a conventional torch, but this was not found to be an advantage for reducing Cr(VI) concentrations."
1232108,Proctor et al. 2002,Is hexavalent chromium carcinogenic via ingestion? A weight-of-evidence review,"Hexavalent chromium [Cr(VI)] is recognized as a human carcinogen via inhalation, based on elevated rates of lung cancer among occupationally exposed workers in certain industries. Cr(VI) is also genotoxic in bacterial and mammalian cell lines. In contrast, scientific panels in the United States and abroad have reviewed the weight of evidence (WOE) and decided that the available data are insufficient to conclude that Cr(VI) is an oral carcinogen. A criterion of 0.2 ppb was established by a California agency for Cr(VI) in drinking water to prevent cancer, however, this criterion was withdrawn in November, 2001. This criterion was remarkably lower than the promulgated California and federal drinking-water standards for total chromium of 50 ppb and 100 ppb, respectively. Both of the promulgated standards are designed to be protective of humans who ingest Cr(VI). This article describes a WOE analysis to examine the likelihood that Cr(VI) in drinking water poses a cancer hazard at the current U.S. drinking-water standard. The results indicate that: (1) From the historical epidemiological studies, there are a few reports of increased rates of digestive system cancer among Cr(VI)-exposed workers, although most are not statistically significant; (2) the preponderance of evidence from recent epidemiological studies of Cr(VI)-exposed workers does not support an increased risk of cancer outside of the respiratory system; (3) studies of four environmentally exposed populations are negative; (4) there is only one lifetime animal feeding study, and the findings from that study are considered to be flawed and inconclusive; and (5) recent kinetics and in vivo genotoxicity data demonstrate that Cr(VI) is reduced to nontoxic Cr(III) in saliva, in the acidic conditions of the stomach, and in blood. In short, at concentrations at least as high as the current U.S. maximum contaminant level (100 ppb), and probably at least an order of magnitude higher, Cr(VI) is reduced to Cr(III) prior to or upon systemic absorption. The weight of scientific evidence supports that Cr(VI) is not carcinogenic in humans via the oral route of exposure at permissible drinking-water concentrations.","Is hexavalent chromium carcinogenic via ingestion? A weight-of-evidence review Abs: Hexavalent chromium [Cr(VI)] is recognized as a human carcinogen via inhalation, based on elevated rates of lung cancer among occupationally exposed workers in certain industries. Cr(VI) is also genotoxic in bacterial and mammalian cell lines. In contrast, scientific panels in the United States and abroad have reviewed the weight of evidence (WOE) and decided that the available data are insufficient to conclude that Cr(VI) is an oral carcinogen. A criterion of 0.2 ppb was established by a California agency for Cr(VI) in drinking water to prevent cancer, however, this criterion was withdrawn in November, 2001. This criterion was remarkably lower than the promulgated California and federal drinking-water standards for total chromium of 50 ppb and 100 ppb, respectively. Both of the promulgated standards are designed to be protective of humans who ingest Cr(VI). This article describes a WOE analysis to examine the likelihood that Cr(VI) in drinking water poses a cancer hazard at the current U.S. drinking-water standard. The results indicate that: (1) From the historical epidemiological studies, there are a few reports of increased rates of digestive system cancer among Cr(VI)-exposed workers, although most are not statistically significant; (2) the preponderance of evidence from recent epidemiological studies of Cr(VI)-exposed workers does not support an increased risk of cancer outside of the respiratory system; (3) studies of four environmentally exposed populations are negative; (4) there is only one lifetime animal feeding study, and the findings from that study are considered to be flawed and inconclusive; and (5) recent kinetics and in vivo genotoxicity data demonstrate that Cr(VI) is reduced to nontoxic Cr(III) in saliva, in the acidic conditions of the stomach, and in blood. In short, at concentrations at least as high as the current U.S. maximum contaminant level (100 ppb), and probably at least an order of magnitude higher, Cr(VI) is reduced to Cr(III) prior to or upon systemic absorption. The weight of scientific evidence supports that Cr(VI) is not carcinogenic in humans via the oral route of exposure at permissible drinking-water concentrations."
1232106,Gorbi et al. 2002,Is Cr(VI) toxicity to Daphnia magna modified by food availability or algal exudates? The hypothesis of a specific chromium/algae/exudates interaction,"The long-term effects of Cr(VI) on life history traits of Daphnia magna Straus were studied in relation to different feeding conditions or to the presence of Scenedesmus acutus exudates, which had proved to reduce chromium toxicity to the alga. In high feeding conditions the concentration of 14 microg Cr(VI)/L had negative effects on survival, growth and fecundity. In low feeding conditions the effects on growth were not evident, but daphnids changed the reproductive strategy normally adopted in case of food shortage and showed a daily rate of newborn production higher than control; however, newborn were of a smaller size and less resistant to starvation. The most relevant effect of Cr was a shortening of the daphnid life span, which was independent of the feeding conditions and occurred also when growth and daily rate of neonate production were not affected. The algal exudates resulted ineffective in reducing Cr toxicity to daphnids, but caused a strong decrease in daphnid fecundity. Further experiments on S. acutus demonstrated that the detoxifying effect observed in the algae might involve a specific Cr/algae/exudates interaction, which occurs only when the algae are previously subjected to a short-time stress by chromium.","Is Cr(VI) toxicity to Daphnia magna modified by food availability or algal exudates? The hypothesis of a specific chromium/algae/exudates interaction Abs: The long-term effects of Cr(VI) on life history traits of Daphnia magna Straus were studied in relation to different feeding conditions or to the presence of Scenedesmus acutus exudates, which had proved to reduce chromium toxicity to the alga. In high feeding conditions the concentration of 14 microg Cr(VI)/L had negative effects on survival, growth and fecundity. In low feeding conditions the effects on growth were not evident, but daphnids changed the reproductive strategy normally adopted in case of food shortage and showed a daily rate of newborn production higher than control; however, newborn were of a smaller size and less resistant to starvation. The most relevant effect of Cr was a shortening of the daphnid life span, which was independent of the feeding conditions and occurred also when growth and daily rate of neonate production were not affected. The algal exudates resulted ineffective in reducing Cr toxicity to daphnids, but caused a strong decrease in daphnid fecundity. Further experiments on S. acutus demonstrated that the detoxifying effect observed in the algae might involve a specific Cr/algae/exudates interaction, which occurs only when the algae are previously subjected to a short-time stress by chromium."
1232104,Thompson et al. 2002,Comparison of the toxicity of chromium III and chromium VI to cyanobacteria,,Comparison of the toxicity of chromium III and chromium VI to cyanobacteria Abs: 
1232103,Carriquiriborde and  Ronco 2002,"Sensitivity of the neotropical teleost Odonthestes bonariensis (pisces, Atherinidae) to chromium(VI), copper(II), and cadmium(II)",,"Sensitivity of the neotropical teleost Odonthestes bonariensis (pisces, Atherinidae) to chromium(VI), copper(II), and cadmium(II) Abs: "
1232100,Kim et al. 2002,Toxicity of hexavalent chromium to Daphnia magna: influence of reduction reaction by ferrous iron,"The reaction kinetics of hexavalent chromium with ferrous ions were studied to determine the influence of reduction on the toxicity of chromium to aquatic organisms. The changes in chemical forms of the chromate in the presence of ferrous ions were examined in a bioassay system using Daphnia magna as a test organism. This study demonstrated that the reaction kinetics of chromate with ferrous ions showed a significant decrease of chromate concentration with the second-order rate coefficient (k) for the reduction of Cr(VI) being determined as 55.2M(-1)s(-1). The concentration of Cr(VI) remaining in the solution decreased as the ratio of ferrous ion to chromate increased, revealing a non-stoichiometric reaction due to oxygenation and the moderately alkaline pH of the solutions. The toxicity test indicated that the bioavailability of chromate to D. magna was reduced in the presence of Fe(II) and that it decreased further with increasing Fe(II) concentrations. However, the toxic effect of chromate to aquatic organisms was not controlled kinetically in the presence of ferrous ions. It was also found that LC(50) of chromate to D. magna decreased about 1.5-fold as the test period increased from 24 to 48h in the presence of Fe(II).","Toxicity of hexavalent chromium to Daphnia magna: influence of reduction reaction by ferrous iron Abs: The reaction kinetics of hexavalent chromium with ferrous ions were studied to determine the influence of reduction on the toxicity of chromium to aquatic organisms. The changes in chemical forms of the chromate in the presence of ferrous ions were examined in a bioassay system using Daphnia magna as a test organism. This study demonstrated that the reaction kinetics of chromate with ferrous ions showed a significant decrease of chromate concentration with the second-order rate coefficient (k) for the reduction of Cr(VI) being determined as 55.2M(-1)s(-1). The concentration of Cr(VI) remaining in the solution decreased as the ratio of ferrous ion to chromate increased, revealing a non-stoichiometric reaction due to oxygenation and the moderately alkaline pH of the solutions. The toxicity test indicated that the bioavailability of chromate to D. magna was reduced in the presence of Fe(II) and that it decreased further with increasing Fe(II) concentrations. However, the toxic effect of chromate to aquatic organisms was not controlled kinetically in the presence of ferrous ions. It was also found that LC(50) of chromate to D. magna decreased about 1.5-fold as the test period increased from 24 to 48h in the presence of Fe(II)."
1232099,Assfalg et al. 2002,The metal reductase activity of some multiheme cytochromes c: NMR structural characterization of the reduction of chromium(VI) to chromium(III) by cytochrome c(7),"The redox reaction between CrO(4)(2-) and the fully reduced three-heme cytochrome c(7) from Desulfuromonas acetoxidans to give chromium(III) and the fully oxidized protein has been followed by NMR spectroscopy. The hyperfine coupling between the oxidized protein protons and chromium(III), which remains bound to the protein, gives rise to line-broadening effects on the NMR resonances that can be transformed into proton-metal distance restraints. Structure calculations based on these unconventional constraints allowed us to demonstrate that chromium(III) binds at a unique site and to locate it on the protein surface. The metal ion is located 7.9 +/- 0.4 A from the iron of heme IV, 16.3 +/- 0.7 A from the iron of heme III, and 22.5 +/- 0.5 A from the iron of heme I. Shift changes caused by the presence of unreactive MoO(4)(2-), a CrO(4)(2-) analogue, indicate the involvement of the same protein area in the anion binding. The titration of the oxidation of cytochrome c(7) shows a detailed mechanism of action. The presence of a specific binding site supports the hypothesis of the biological role of this cytochrome as a metal reductase.","The metal reductase activity of some multiheme cytochromes c: NMR structural characterization of the reduction of chromium(VI) to chromium(III) by cytochrome c(7) Abs: The redox reaction between CrO(4)(2-) and the fully reduced three-heme cytochrome c(7) from Desulfuromonas acetoxidans to give chromium(III) and the fully oxidized protein has been followed by NMR spectroscopy. The hyperfine coupling between the oxidized protein protons and chromium(III), which remains bound to the protein, gives rise to line-broadening effects on the NMR resonances that can be transformed into proton-metal distance restraints. Structure calculations based on these unconventional constraints allowed us to demonstrate that chromium(III) binds at a unique site and to locate it on the protein surface. The metal ion is located 7.9 +/- 0.4 A from the iron of heme IV, 16.3 +/- 0.7 A from the iron of heme III, and 22.5 +/- 0.5 A from the iron of heme I. Shift changes caused by the presence of unreactive MoO(4)(2-), a CrO(4)(2-) analogue, indicate the involvement of the same protein area in the anion binding. The titration of the oxidation of cytochrome c(7) shows a detailed mechanism of action. The presence of a specific binding site supports the hypothesis of the biological role of this cytochrome as a metal reductase."
1232098,Samantary 2002,Biochemical responses of Cr-tolerant and Cr-sensitive mung bean cultivars grown on varying levels of chromium,"Biochemical investigations were carried out in Cr-tolerant and Cr-sensitive cultivars of mung bean (Vigna radiata L.) with different concentrations of hexavalent chromium (as K2Cr2O7) in hydroponics culture. Seeds were germinated and grown in the presence or absence of chromium under controlled environmental conditions. Protein, pigment and enzyme analysis were conducted in both Cr-tolerant and Cr-sensitive cultivars of mung bean after 72 h of treatments. Chlorophyll and protein contents were reduced in Cr-sensitive cultivars more than those of the tolerant ones. The enzyme activity varied among the Cr-tolerant and Cr-sensitive ones. Activities of catalase, peroxidase, glucose-6-phosphate dehydrogenase and superoxide dismutase were greater in Cr-sensitive than tolerant cultivars.","Biochemical responses of Cr-tolerant and Cr-sensitive mung bean cultivars grown on varying levels of chromium Abs: Biochemical investigations were carried out in Cr-tolerant and Cr-sensitive cultivars of mung bean (Vigna radiata L.) with different concentrations of hexavalent chromium (as K2Cr2O7) in hydroponics culture. Seeds were germinated and grown in the presence or absence of chromium under controlled environmental conditions. Protein, pigment and enzyme analysis were conducted in both Cr-tolerant and Cr-sensitive cultivars of mung bean after 72 h of treatments. Chlorophyll and protein contents were reduced in Cr-sensitive cultivars more than those of the tolerant ones. The enzyme activity varied among the Cr-tolerant and Cr-sensitive ones. Activities of catalase, peroxidase, glucose-6-phosphate dehydrogenase and superoxide dismutase were greater in Cr-sensitive than tolerant cultivars."
1232095,Ding and  Shi 2002,Molecular mechanisms of Cr(VI)-induced carcinogenesis,"Although Cr(VI)-containing compounds are well documented carcinogens, their mechanism of action is still not well understood. Recent studies have suggested that reduction of Cr(VI) to its lower oxidation states and related free radical reactions play an important role in Cr(VI)-induced carcinogenesis. This article summarizes recent studies from our laboratory on (a) the reduction of Cr(VI) by ascorbate, diol- and thiol-containing molecules, certain flavoenzymes, cell organelles, intact cells, and whole animals; (b) free radical production in both non-cellular and cellular systems; and (c) Cr(VI)-induced DNA damage, activation of nuclear transcription factor KB (NF-kappaB), activator protein-1, p53, hypoxia-inducible factor-1, vascular endothelial growth factor, tyrosine phosphorylation, apoptosis, cell growth arrest, and gene expression profile.","Molecular mechanisms of Cr(VI)-induced carcinogenesis Abs: Although Cr(VI)-containing compounds are well documented carcinogens, their mechanism of action is still not well understood. Recent studies have suggested that reduction of Cr(VI) to its lower oxidation states and related free radical reactions play an important role in Cr(VI)-induced carcinogenesis. This article summarizes recent studies from our laboratory on (a) the reduction of Cr(VI) by ascorbate, diol- and thiol-containing molecules, certain flavoenzymes, cell organelles, intact cells, and whole animals; (b) free radical production in both non-cellular and cellular systems; and (c) Cr(VI)-induced DNA damage, activation of nuclear transcription factor KB (NF-kappaB), activator protein-1, p53, hypoxia-inducible factor-1, vascular endothelial growth factor, tyrosine phosphorylation, apoptosis, cell growth arrest, and gene expression profile."
1232094,Pattanapipitpaisal et al. 2002,Reduction of Cr(VI) and bioaccumulation of chromium by gram positive and gram negative microorganisms not previously exposed to Cr-stress,"Resistance to Cr(VI) is usually associated with its cellular exclusion, precluding enrichment techniques for the isolation of organisms accumulating Cr(VI) via bioreduction to insoluble Cr(III). A technique was developed to screen for potential Cr(VI) reduction in approx. 2000 isolates from a coastal environment, based on the non-specific reduction of selenite and tellurite to Se0 and Te0, and reduction of tetrazolium blue to insoluble blue formazan. The most promising strains were further screened in liquid culture, giving three, which were identified by 16S rRNA sequence analysis as Bacillus pumilus, Exiguobacterium aurantiacum and Pseudomonas synxantha, all of which reduced 100 microM Cr(VI) anaerobically, without growth. The respective removal of Cr(VI) was 90% and 80% by B. pumilus and E. aurantiacum after 48 h and 80% and by P. synxantha after 192 h. With the gram positive strains Cr(VI) promoted loss of flagella and, in the case of B. pumilus, lysis of some cells, but Cr was deposited as an exocellular precipitate which was identified as containing Cr and P using energy dispersive X-ray microanalysis (EDAX). This prompted the testing of Citrobacter sp. N14 (subsequently re-assigned by 16S rRNA sequence analysis and biochemical studies as a strain of Serratia) which bioprecipitates metal cation phosphates via enzymatically-liberated phosphate. This strain reduced Cr(VI) at a rate comparable to that of P. synxantha but Cr(III) was not bioprecipitated where La(III) was removed as LaPO4, even though a similar amount of phosphate was produced in the presence of Cr(III). Since B. pumilus removed most of the Cr(VI), with the formation of cell-bound CrPO4 implicated, this suggests that this strain could have future bioprocess potential.","Reduction of Cr(VI) and bioaccumulation of chromium by gram positive and gram negative microorganisms not previously exposed to Cr-stress Abs: Resistance to Cr(VI) is usually associated with its cellular exclusion, precluding enrichment techniques for the isolation of organisms accumulating Cr(VI) via bioreduction to insoluble Cr(III). A technique was developed to screen for potential Cr(VI) reduction in approx. 2000 isolates from a coastal environment, based on the non-specific reduction of selenite and tellurite to Se0 and Te0, and reduction of tetrazolium blue to insoluble blue formazan. The most promising strains were further screened in liquid culture, giving three, which were identified by 16S rRNA sequence analysis as Bacillus pumilus, Exiguobacterium aurantiacum and Pseudomonas synxantha, all of which reduced 100 microM Cr(VI) anaerobically, without growth. The respective removal of Cr(VI) was 90% and 80% by B. pumilus and E. aurantiacum after 48 h and 80% and by P. synxantha after 192 h. With the gram positive strains Cr(VI) promoted loss of flagella and, in the case of B. pumilus, lysis of some cells, but Cr was deposited as an exocellular precipitate which was identified as containing Cr and P using energy dispersive X-ray microanalysis (EDAX). This prompted the testing of Citrobacter sp. N14 (subsequently re-assigned by 16S rRNA sequence analysis and biochemical studies as a strain of Serratia) which bioprecipitates metal cation phosphates via enzymatically-liberated phosphate. This strain reduced Cr(VI) at a rate comparable to that of P. synxantha but Cr(III) was not bioprecipitated where La(III) was removed as LaPO4, even though a similar amount of phosphate was produced in the presence of Cr(III). Since B. pumilus removed most of the Cr(VI), with the formation of cell-bound CrPO4 implicated, this suggests that this strain could have future bioprocess potential."
1232093,Aksu et al. 2002,Equilibrium modelling of individual and simultaneous biosorption of chromium(VI) and nickel(II) onto dried activated sludge,"The biosorption of chromium(VI) and nickel(II) ions, both singly and in combination, by dried activated sludge was investigated in a batch system as a function of initial pH and single- and dual-metal ion concentrations. The working initial pH values for single chromium(VI) and nickel(II) biosorptions were determined as 1.0 and 4.5, respectively. It was observed that the co-ion effect on the equilibrium uptake became more pronounced as the co-ion concentration in solution increased and pH level increased for chromium(VI) and decreased for nickel(II). Adsorption isotherms were developed for both the single- and dual-metal ion systems at these two pH values and expressed by the mono- and multi-component Langmuir and Freundlich adsorption models and model parameters were estimated by the non-linear regression. It was seen that the mono-component adsorption equilibrium data fitted very well to both the mono-component adsorption models for both the components and the pH values studied while the multi-component Freundlich adsorption model adequately predicted the multi-component adsorption equilibrium data at moderate ranges of initial mixture concentrations for both the studied pH values.","Equilibrium modelling of individual and simultaneous biosorption of chromium(VI) and nickel(II) onto dried activated sludge Abs: The biosorption of chromium(VI) and nickel(II) ions, both singly and in combination, by dried activated sludge was investigated in a batch system as a function of initial pH and single- and dual-metal ion concentrations. The working initial pH values for single chromium(VI) and nickel(II) biosorptions were determined as 1.0 and 4.5, respectively. It was observed that the co-ion effect on the equilibrium uptake became more pronounced as the co-ion concentration in solution increased and pH level increased for chromium(VI) and decreased for nickel(II). Adsorption isotherms were developed for both the single- and dual-metal ion systems at these two pH values and expressed by the mono- and multi-component Langmuir and Freundlich adsorption models and model parameters were estimated by the non-linear regression. It was seen that the mono-component adsorption equilibrium data fitted very well to both the mono-component adsorption models for both the components and the pH values studied while the multi-component Freundlich adsorption model adequately predicted the multi-component adsorption equilibrium data at moderate ranges of initial mixture concentrations for both the studied pH values."
1232092,Castillo et al. 2002,Chemically facilitated chromium(VI) transport throughout an anion-exchange membrane application to an optical sensor for chromium(VI) monitoring,"The Raipore R1030 membrane, an anion-exchange membrane containing ammonium groups as ionogenic groups, was evaluated as the interface of an optical sensor for Cr(VI), and the effect of chemical parameters affecting Cr(VI) transport were studied. Good transport features were obtained, demonstrating the suitability of the Raipore R1030 membrane for this application. Thus, an optical sensor for chromium(VI) monitoring in industrial process waters was developed. The sensor is based on the renewable reagent approach and uses the Raipore R1030 membrane as the interface between the sample and the sensor head, which contains 1,5-diphenylcarbazide as spectrophotometric reagent for chromium. Chromium(VI) crosses the membrane and reacts with the reagent inside the sensor head, resulting in changes in the absorption of light. These changes are monitored in situ through a system of optical fibers. The sensor performance was tested by analysing samples from a waste water treatment plant for effluents from electroplating industries.","Chemically facilitated chromium(VI) transport throughout an anion-exchange membrane application to an optical sensor for chromium(VI) monitoring Abs: The Raipore R1030 membrane, an anion-exchange membrane containing ammonium groups as ionogenic groups, was evaluated as the interface of an optical sensor for Cr(VI), and the effect of chemical parameters affecting Cr(VI) transport were studied. Good transport features were obtained, demonstrating the suitability of the Raipore R1030 membrane for this application. Thus, an optical sensor for chromium(VI) monitoring in industrial process waters was developed. The sensor is based on the renewable reagent approach and uses the Raipore R1030 membrane as the interface between the sample and the sensor head, which contains 1,5-diphenylcarbazide as spectrophotometric reagent for chromium. Chromium(VI) crosses the membrane and reacts with the reagent inside the sensor head, resulting in changes in the absorption of light. These changes are monitored in situ through a system of optical fibers. The sensor performance was tested by analysing samples from a waste water treatment plant for effluents from electroplating industries."
1232091,Stasinakis et al. 2002,Effect of chromium(VI) on bacterial kinetics of heterotrophic biomass of activated sludge,"The effect of hexavalent chromium, Cr(VI), on the maximum specific growth rate, mu(m) and biomass yield, Y(H), of heterotrophic biomass was studied in batch tests conducted under high (= 10) and low (= 1.5) substrate-to-biomass ratios (S0/X0). The effects of sludge age and biomass acclimatization to Cr(VI) on the bacterial kinetics were also studied. The mu(m) values were determined by measuring oxygen uptake rate (OUR) and volatile suspended solids (VSS) increase. Cr(VI) concentrations equal or greater than 10 mg l(-1) inhibited the growth of unacclimatized activated sludge and caused a significant decrease in mu(m) and Y(H) values. The acclimatization of biomass and the selection of a high operating sludge age reduced the inhibitory effect of Cr(VI). At a sludge age of 20 days, Cr(VI) concentrations of &lt;10 mg l(-1) stimulated bacterial growth as evidenced by an increase in both the mu(m) and Y(H) values. Determining mu(m) values by OUR and VSS methods, revealed that the presence of Cr(VI) in unacclimatized biomass caused an inhibitory effect mostly on substrate oxidation, while in acclimatized biomass, anabolic pathways were inhibited more.","Effect of chromium(VI) on bacterial kinetics of heterotrophic biomass of activated sludge Abs: The effect of hexavalent chromium, Cr(VI), on the maximum specific growth rate, mu(m) and biomass yield, Y(H), of heterotrophic biomass was studied in batch tests conducted under high (= 10) and low (= 1.5) substrate-to-biomass ratios (S0/X0). The effects of sludge age and biomass acclimatization to Cr(VI) on the bacterial kinetics were also studied. The mu(m) values were determined by measuring oxygen uptake rate (OUR) and volatile suspended solids (VSS) increase. Cr(VI) concentrations equal or greater than 10 mg l(-1) inhibited the growth of unacclimatized activated sludge and caused a significant decrease in mu(m) and Y(H) values. The acclimatization of biomass and the selection of a high operating sludge age reduced the inhibitory effect of Cr(VI). At a sludge age of 20 days, Cr(VI) concentrations of &lt;10 mg l(-1) stimulated bacterial growth as evidenced by an increase in both the mu(m) and Y(H) values. Determining mu(m) values by OUR and VSS methods, revealed that the presence of Cr(VI) in unacclimatized biomass caused an inhibitory effect mostly on substrate oxidation, while in acclimatized biomass, anabolic pathways were inhibited more."
1232090,Gao et al. 2002,p38 Signaling-mediated hypoxia-inducible factor 1alpha and vascular endothelial growth factor induction by Cr(VI) in DU145 human prostate carcinoma cells,"Chromium(VI) (Cr(VI)) is widely used in industry and is a potent inducer of tumors in animals. The present study demonstrates that Cr(VI) induces hypoxia-inducible factor 1 (HIF-1) activity through the specific expression of HIF-1alpha but not HIF-1beta subunit and increases the level of vascular endothelial growth factor (VEGF) expression in DU145 human prostate carcinoma cells. To dissect the signaling pathways involved in Cr(VI)-induced HIF-1 expression, we found that p38 mitogen-activated protein kinase signaling was required for HIF-1alpha expression induced by Cr(VI). Neither phosphatidylinositol 3-kinase nor extracellular signal-regulated kinase activity was required for Cr(VI)-induced HIF-1 expression. Cr(VI) induced expression of HIF-1 and VEGF through the production of reactive oxygen species in DU145 cells. The major species of reactive oxygen species responsible for the induction of HIF-1 and VEGF expression is H(2)O(2). These results suggest that the expression of HIF-1 and VEGF induced by Cr(VI) may be an important signaling pathway in the Cr(VI)-induced carcinogenesis.","p38 Signaling-mediated hypoxia-inducible factor 1alpha and vascular endothelial growth factor induction by Cr(VI) in DU145 human prostate carcinoma cells Abs: Chromium(VI) (Cr(VI)) is widely used in industry and is a potent inducer of tumors in animals. The present study demonstrates that Cr(VI) induces hypoxia-inducible factor 1 (HIF-1) activity through the specific expression of HIF-1alpha but not HIF-1beta subunit and increases the level of vascular endothelial growth factor (VEGF) expression in DU145 human prostate carcinoma cells. To dissect the signaling pathways involved in Cr(VI)-induced HIF-1 expression, we found that p38 mitogen-activated protein kinase signaling was required for HIF-1alpha expression induced by Cr(VI). Neither phosphatidylinositol 3-kinase nor extracellular signal-regulated kinase activity was required for Cr(VI)-induced HIF-1 expression. Cr(VI) induced expression of HIF-1 and VEGF through the production of reactive oxygen species in DU145 cells. The major species of reactive oxygen species responsible for the induction of HIF-1 and VEGF expression is H(2)O(2). These results suggest that the expression of HIF-1 and VEGF induced by Cr(VI) may be an important signaling pathway in the Cr(VI)-induced carcinogenesis."
1232089,Gunaratnam et al. 2002,Pretreatment of rats with the inducing agents phenobarbitone and 3-methylcholanthrene ameliorates the toxicity of chromium (VI) in hepatocytes,"To exert cytotoxicity chromium VI (Cr(VI)) has to be reduced inside cells. This is achieved through both enzymatic and non-enzymatic mechanisms. Enzymatic mechanisms include DT-diaphorase, cytochrome P450, and NADPH cytochrome c reductase, and non-enzymatic mechanisms involve reduced glutathione (GSH) and ascorbic acid. The extent of cytotoxicity of Cr(VI) may thus be influenced by the availability of non-enzymatic reductants, and by the activities of the reductase enzymes. In the present paper we have investigated the effect of pretreatment with the inducing agents, phenobarbitone (PB) and 3-methylcholanthrene (3-MC), on the response of rat hepatocytes to Cr(VI). Pretreatment with PB increased the activity of NADPH cytochrome c reductase, and 3-MC increased DT-diaphorase activity in hepatocytes. Both inducers increased cytochrome P450 content, while neither influenced intracellular GSH content or the activity of glutathione reductase. Pretreatment with either PB or 3-MC resulted in amelioration of Cr(VI) toxicity both in terms of hepatocyte viability, and to a greater extent, in terms of Cr(VI) induced GSH loss. We propose that the inducing agents increase the amount of enzymatic reduction of Cr(VI) relative to non-enzymatic reduction. Thus, less GSH is used in the reduction of Cr(VI), and intracellular GSH does not fall as rapidly as in cells from control animals therefore cell integrity is better maintained. Exposure to environmental inducing agents in vivo may also alter the response of human tissues to Cr(VI).","Pretreatment of rats with the inducing agents phenobarbitone and 3-methylcholanthrene ameliorates the toxicity of chromium (VI) in hepatocytes Abs: To exert cytotoxicity chromium VI (Cr(VI)) has to be reduced inside cells. This is achieved through both enzymatic and non-enzymatic mechanisms. Enzymatic mechanisms include DT-diaphorase, cytochrome P450, and NADPH cytochrome c reductase, and non-enzymatic mechanisms involve reduced glutathione (GSH) and ascorbic acid. The extent of cytotoxicity of Cr(VI) may thus be influenced by the availability of non-enzymatic reductants, and by the activities of the reductase enzymes. In the present paper we have investigated the effect of pretreatment with the inducing agents, phenobarbitone (PB) and 3-methylcholanthrene (3-MC), on the response of rat hepatocytes to Cr(VI). Pretreatment with PB increased the activity of NADPH cytochrome c reductase, and 3-MC increased DT-diaphorase activity in hepatocytes. Both inducers increased cytochrome P450 content, while neither influenced intracellular GSH content or the activity of glutathione reductase. Pretreatment with either PB or 3-MC resulted in amelioration of Cr(VI) toxicity both in terms of hepatocyte viability, and to a greater extent, in terms of Cr(VI) induced GSH loss. We propose that the inducing agents increase the amount of enzymatic reduction of Cr(VI) relative to non-enzymatic reduction. Thus, less GSH is used in the reduction of Cr(VI), and intracellular GSH does not fall as rapidly as in cells from control animals therefore cell integrity is better maintained. Exposure to environmental inducing agents in vivo may also alter the response of human tissues to Cr(VI)."
1232088,Bagchi et al. 2002,Cytotoxicity and oxidative mechanisms of different forms of chromium,"Chromium exists mostly in two valence states in nature: hexavalent chromium [chromium(VI)] and trivalent chromium [chromium(III)]. Chromium(VI) is commonly used in industrial chrome plating, welding, painting, metal finishes, steel manufacturing, alloy, cast iron and wood treatment, and is a proven toxin, mutagen and carcinogen. The mechanistic cytotoxicity of chromium(VI) is not completely understood, however, a large number of studies demonstrated that chromium(VI) induces oxidative stress, DNA damage, apoptotic cell death and altered gene expression. Conversely, chromium(III) is essential for proper insulin function and is required for normal protein, fat and carbohydrate metabolism, and is acknowledged as a dietary supplement. In this paper, comparative concentration- and time-dependent effects of chromium(VI) and chromium(III) were demonstrated on increased production of reactive oxygen species (ROS) and lipid peroxidation, enhanced excretion of urinary lipid metabolites, DNA fragmentation and apoptotic cell death in both in vitro and in vivo models. Chromium(VI) demonstrated significantly higher toxicity as compared with chromium(III). To evaluate the role of p53 gene, the dose-dependent effects of chromium(VI) were assessed in female C57BL/6Ntac and p53-deficient C57BL/6TSG p53 mice on enhanced production of ROS, lipid peroxidation and DNA fragmentation in hepatic and brain tissues. Chromium(VI) induced more pronounced oxidative damage in multiple target organs in p53 deficient mice. Comparative studies of chromium(III) picolinate and niacin-bound chromium(III), two popular dietary supplements, reveal that chromium(III) picolinate produces significantly more oxidative stress and DNA damage. Studies have implicated the toxicity of chromium picolinate in renal impairment, skin blisters and pustules, anemia, hemolysis, tissue edema, liver dysfunction; neuronal cell injury, impaired cognitive, perceptual and motor activity; enhanced production of hydroxyl radicals, chromosomal aberration, depletion of antioxidant enzymes, and DNA damage. Recently, chromium picolinate has been shown to be mutagenic and picolinic acid moiety appears to be responsible as studies show that picolinic acid alone is clastogenic. Niacin-bound chromium(III) has been demonstrated to be more bioavailable and efficacious and no toxicity has been reported. In summary, these studies demonstrate that a cascade of cellular events including oxidative stress, genomic DNA damage and modulation of apoptotic regulatory gene p53 are involved in chromium(VI)-induced toxicity and carcinogenesis. The safety of chromium(III) is largely dependent on the ligand, and adequate clinical studies are warranted to demonstrate the safety and efficacy of chromium(III) for human consumption.","Cytotoxicity and oxidative mechanisms of different forms of chromium Abs: Chromium exists mostly in two valence states in nature: hexavalent chromium [chromium(VI)] and trivalent chromium [chromium(III)]. Chromium(VI) is commonly used in industrial chrome plating, welding, painting, metal finishes, steel manufacturing, alloy, cast iron and wood treatment, and is a proven toxin, mutagen and carcinogen. The mechanistic cytotoxicity of chromium(VI) is not completely understood, however, a large number of studies demonstrated that chromium(VI) induces oxidative stress, DNA damage, apoptotic cell death and altered gene expression. Conversely, chromium(III) is essential for proper insulin function and is required for normal protein, fat and carbohydrate metabolism, and is acknowledged as a dietary supplement. In this paper, comparative concentration- and time-dependent effects of chromium(VI) and chromium(III) were demonstrated on increased production of reactive oxygen species (ROS) and lipid peroxidation, enhanced excretion of urinary lipid metabolites, DNA fragmentation and apoptotic cell death in both in vitro and in vivo models. Chromium(VI) demonstrated significantly higher toxicity as compared with chromium(III). To evaluate the role of p53 gene, the dose-dependent effects of chromium(VI) were assessed in female C57BL/6Ntac and p53-deficient C57BL/6TSG p53 mice on enhanced production of ROS, lipid peroxidation and DNA fragmentation in hepatic and brain tissues. Chromium(VI) induced more pronounced oxidative damage in multiple target organs in p53 deficient mice. Comparative studies of chromium(III) picolinate and niacin-bound chromium(III), two popular dietary supplements, reveal that chromium(III) picolinate produces significantly more oxidative stress and DNA damage. Studies have implicated the toxicity of chromium picolinate in renal impairment, skin blisters and pustules, anemia, hemolysis, tissue edema, liver dysfunction; neuronal cell injury, impaired cognitive, perceptual and motor activity; enhanced production of hydroxyl radicals, chromosomal aberration, depletion of antioxidant enzymes, and DNA damage. Recently, chromium picolinate has been shown to be mutagenic and picolinic acid moiety appears to be responsible as studies show that picolinic acid alone is clastogenic. Niacin-bound chromium(III) has been demonstrated to be more bioavailable and efficacious and no toxicity has been reported. In summary, these studies demonstrate that a cascade of cellular events including oxidative stress, genomic DNA damage and modulation of apoptotic regulatory gene p53 are involved in chromium(VI)-induced toxicity and carcinogenesis. The safety of chromium(III) is largely dependent on the ligand, and adequate clinical studies are warranted to demonstrate the safety and efficacy of chromium(III) for human consumption."
1232087,Sun and  Huang 2002,Co-removal of hexavalent chromium during copper precipitation,"In our recent study using the nucleated precipitation technology to treat plating wastewater, it was found that about one half of hexavalent chromium was co-removed with copper, nickel and zinc. Since hexavalent chromium could not react with either hydroxide or carbonate to from precipitates, this study was undertaken to evaluate the mechanism(s) involved in the chromium co-removal. Batch tests were conducted with synthetic solutions containing either only copper or both copper and hexavalent chromium. Metal precipitation was induced by adding Na2CO3 to different pH, and the quantitative removal of copper and chromium was determined. Besides, the [Cr]/[Cu] molar ratio of produced precipitates were also assessed in conjunction with the EDAX analysis to determine their compositions. Experimental results indicate that for pure copper solution, precipitation begins at pH 6.0, and completes at pH 7.0. The chemical forms of the precipitates are copper carbonates [CuCO3 x Cu(OH)2 and CuCO3 x 2Cu(OH)2]. On the other hand, in a bi-metal solution of copper plus chromium, precipitation of copper begins at about pH 5.0, and copper precipitation is always accompanied by some chromium removal. From the removal stoichiometry of the two metals, it is found that at low pH, the co-removal is a result of &quot;co-precipitation&quot; which results in the formation of CuCrO4 crystallites. Once such crystallites are formed, they provide a heterogeneous environment which enhances an early formation of copper carbonate at a lower pH (below 5.5). It is further found that once copper carbonate precipitates are produced, the remaining soluble will precipitate in such form, and at this stage further removal of copper is no longer accompanied by additional chromium removal. The test data also reflect that the produced copper carbonates are positively charged, as verified by zeta potential measurement, at pH below 7.5. Thus they are able to adsorb some anionic chromium (existing as chromate) through electrostatic attraction and/or inorganic ligand exchange. At pH of 6 to 10, the extent of adsorption decreases with increasing pH, and the adsorption capacity seems to coincide with the progressive reduction of positive zeta potentials of the precipitated particles.","Co-removal of hexavalent chromium during copper precipitation Abs: In our recent study using the nucleated precipitation technology to treat plating wastewater, it was found that about one half of hexavalent chromium was co-removed with copper, nickel and zinc. Since hexavalent chromium could not react with either hydroxide or carbonate to from precipitates, this study was undertaken to evaluate the mechanism(s) involved in the chromium co-removal. Batch tests were conducted with synthetic solutions containing either only copper or both copper and hexavalent chromium. Metal precipitation was induced by adding Na2CO3 to different pH, and the quantitative removal of copper and chromium was determined. Besides, the [Cr]/[Cu] molar ratio of produced precipitates were also assessed in conjunction with the EDAX analysis to determine their compositions. Experimental results indicate that for pure copper solution, precipitation begins at pH 6.0, and completes at pH 7.0. The chemical forms of the precipitates are copper carbonates [CuCO3 x Cu(OH)2 and CuCO3 x 2Cu(OH)2]. On the other hand, in a bi-metal solution of copper plus chromium, precipitation of copper begins at about pH 5.0, and copper precipitation is always accompanied by some chromium removal. From the removal stoichiometry of the two metals, it is found that at low pH, the co-removal is a result of &quot;co-precipitation&quot; which results in the formation of CuCrO4 crystallites. Once such crystallites are formed, they provide a heterogeneous environment which enhances an early formation of copper carbonate at a lower pH (below 5.5). It is further found that once copper carbonate precipitates are produced, the remaining soluble will precipitate in such form, and at this stage further removal of copper is no longer accompanied by additional chromium removal. The test data also reflect that the produced copper carbonates are positively charged, as verified by zeta potential measurement, at pH below 7.5. Thus they are able to adsorb some anionic chromium (existing as chromate) through electrostatic attraction and/or inorganic ligand exchange. At pH of 6 to 10, the extent of adsorption decreases with increasing pH, and the adsorption capacity seems to coincide with the progressive reduction of positive zeta potentials of the precipitated particles."
1232086,Rao et al. 2002,Removal of Cr6 + and Ni2+ from aqueous solution using bagasse and fly ash,"Raw bagasse and fly ash, the waste generated in sugar mills and boilers respectively have been used as low-cost potential adsorbents. Raw bagasse was pretreated with 0.1N NaOH followed by 0.1N CH3COOH before its application. These low-cost adsorbents were used for the removal of chromium and nickel from an aqueous solution. The kinetics of adsorption and extent of adsorption at equilibrium are dependent on the physical and chemical characteristics of the adsorbent, adsorbate and experimental system. The effect of hydrogen ion concentration, contact time, sorbent dose, initial concentrations of adsorbate and adsorbent and particle size on the uptake of chromium and nickel were studied in batch experiments. The Sorption data has been correlated with Langmuir, Freundlich and Bhattacharya and Venkobachar adsorption models. The efficiencies of adsorbent materials for the removal of Cr(VI) and Ni(II) were found to be between 56.2 and 96.2% and 83.6 and 100%, respectively. These results were obtained at the optimized conditions of pH, contact time, sorbent dose, sorbate concentration of 100 mg/l and with the variation of adsorbent particles size between 0.075 and 4.75 mm. The order of selectivity is powdered activated carbon &gt; bagasse &gt; fly ash for Cr(VI) removal and powdered activated carbon &gt; fly ash &gt; bagasse for Ni(II) removal.","Removal of Cr6 + and Ni2+ from aqueous solution using bagasse and fly ash Abs: Raw bagasse and fly ash, the waste generated in sugar mills and boilers respectively have been used as low-cost potential adsorbents. Raw bagasse was pretreated with 0.1N NaOH followed by 0.1N CH3COOH before its application. These low-cost adsorbents were used for the removal of chromium and nickel from an aqueous solution. The kinetics of adsorption and extent of adsorption at equilibrium are dependent on the physical and chemical characteristics of the adsorbent, adsorbate and experimental system. The effect of hydrogen ion concentration, contact time, sorbent dose, initial concentrations of adsorbate and adsorbent and particle size on the uptake of chromium and nickel were studied in batch experiments. The Sorption data has been correlated with Langmuir, Freundlich and Bhattacharya and Venkobachar adsorption models. The efficiencies of adsorbent materials for the removal of Cr(VI) and Ni(II) were found to be between 56.2 and 96.2% and 83.6 and 100%, respectively. These results were obtained at the optimized conditions of pH, contact time, sorbent dose, sorbate concentration of 100 mg/l and with the variation of adsorbent particles size between 0.075 and 4.75 mm. The order of selectivity is powdered activated carbon &gt; bagasse &gt; fly ash for Cr(VI) removal and powdered activated carbon &gt; fly ash &gt; bagasse for Ni(II) removal."
1232085,Lurie and  Wolfe 2002,"Continuing exposure to hexavalent chromium, a known lung carcinogen: an analysis of OSHA compliance inspections, 1990-2000","<strong>BACKGROUND: </strong>Hexavalent chromium is widely recognized to be a lung carcinogen. However, the U.S. Occupational Safety and Health Administration (OSHA) has failed to reduce the permissible exposure limit (PEL), despite having acknowledged in 1994 that the current limit is too high. In 1993, Public Citizen and the Paper, Allied-Industrial, Chemical and Energy Workers International Union (PACE) petitioned to lower the PEL from the current 100 microg/m(3) to 0.5 microg/m(3) as an 8-hr time-weighted average (TWA).<br /><br /><strong>METHODS: </strong>To assess industry compliance with the current PEL, and to determine the feasibility of achieving the proposed lower limit of 0.5 microg/m(3), we conducted a secondary data analysis of OSHA's Integrated Management Information System (IMIS) database. This database contains 813 measurements of hexavalent chromium exposure from inspections performed during the years 1990-2000.<br /><br /><strong>RESULTS: </strong>There was a statistically significant decline in the annual number of measurements over the study period from 127 in 1990 to 67 in 2000 (F = 0.0009; linear regression). The median TWA measurement was 10 microg/m(3) (range: 0.01-13,960 microg/m(3)) and the median ceiling measurement was 40.5 microg/m(3) (range: 0.25-25,000 microg/m(3)). Neither median TWA nor median ceiling exposures (if hexavalent chromium was detected) declined significantly during the study period (F = 0.065 and 0.57, respectively). Overall, 13.7% of TWA measurements were at or below the Public Citizen/PACE proposed standard; 65.0% were between the Public Citizen/PACE proposal and the current OSHA PEL; and 21.3% exceeded the OSHA PEL. Compared to OSHA measurements, state measurements were less likely to detect hexavalent chromium (40.2% vs. 52.1%; P = 0.0007; chi-square) and less likely to issue any citation (9.3% vs. 19.1%; P = 0.0003), including citations for overexposure if the exposure exceeded the PEL (54.8% vs. 78.8%; P = 0.012).<br /><br /><strong>CONCLUSIONS: </strong>U.S. workers continue to be exposed to dangerously high hexavalent chromium levels, but low exposure levels were found in some industries. Further investigations should examine whether state plans provide weaker enforcement than federal OSHA.","Continuing exposure to hexavalent chromium, a known lung carcinogen: an analysis of OSHA compliance inspections, 1990-2000 Abs: <strong>BACKGROUND: </strong>Hexavalent chromium is widely recognized to be a lung carcinogen. However, the U.S. Occupational Safety and Health Administration (OSHA) has failed to reduce the permissible exposure limit (PEL), despite having acknowledged in 1994 that the current limit is too high. In 1993, Public Citizen and the Paper, Allied-Industrial, Chemical and Energy Workers International Union (PACE) petitioned to lower the PEL from the current 100 microg/m(3) to 0.5 microg/m(3) as an 8-hr time-weighted average (TWA).<br /><br /><strong>METHODS: </strong>To assess industry compliance with the current PEL, and to determine the feasibility of achieving the proposed lower limit of 0.5 microg/m(3), we conducted a secondary data analysis of OSHA's Integrated Management Information System (IMIS) database. This database contains 813 measurements of hexavalent chromium exposure from inspections performed during the years 1990-2000.<br /><br /><strong>RESULTS: </strong>There was a statistically significant decline in the annual number of measurements over the study period from 127 in 1990 to 67 in 2000 (F = 0.0009; linear regression). The median TWA measurement was 10 microg/m(3) (range: 0.01-13,960 microg/m(3)) and the median ceiling measurement was 40.5 microg/m(3) (range: 0.25-25,000 microg/m(3)). Neither median TWA nor median ceiling exposures (if hexavalent chromium was detected) declined significantly during the study period (F = 0.065 and 0.57, respectively). Overall, 13.7% of TWA measurements were at or below the Public Citizen/PACE proposed standard; 65.0% were between the Public Citizen/PACE proposal and the current OSHA PEL; and 21.3% exceeded the OSHA PEL. Compared to OSHA measurements, state measurements were less likely to detect hexavalent chromium (40.2% vs. 52.1%; P = 0.0007; chi-square) and less likely to issue any citation (9.3% vs. 19.1%; P = 0.0003), including citations for overexposure if the exposure exceeded the PEL (54.8% vs. 78.8%; P = 0.012).<br /><br /><strong>CONCLUSIONS: </strong>U.S. workers continue to be exposed to dangerously high hexavalent chromium levels, but low exposure levels were found in some industries. Further investigations should examine whether state plans provide weaker enforcement than federal OSHA."
1232084,Tao et al. 2002,A highly sensitive hexachromium monitor using water core optical fiber with UV LED,"A simply structured, cheap hexachromium monitor was developed. The monitor is based on UV/VIS absorption technique. A 2-m long water core optical fiber was employed as a long path length sample cell and a UV light emitting diode (LED) was used as a light source. The emission profile of the UV LED fits very well with the absorption spectrum of chromate ions in water. Therefore, the light-dispersing element, which is usually used in an optical spectrometer, is not necessary in this monitor design. The water core fiber as a long path length makes the monitor highly sensitive for hexachromium detection. This monitor is specific for hexachromium detection without interference from tri-valence chromium ions. A detection limit of 0.1 ng Cr(VI) ml(-1) was obtained with this simple monitor.","A highly sensitive hexachromium monitor using water core optical fiber with UV LED Abs: A simply structured, cheap hexachromium monitor was developed. The monitor is based on UV/VIS absorption technique. A 2-m long water core optical fiber was employed as a long path length sample cell and a UV light emitting diode (LED) was used as a light source. The emission profile of the UV LED fits very well with the absorption spectrum of chromate ions in water. Therefore, the light-dispersing element, which is usually used in an optical spectrometer, is not necessary in this monitor design. The water core fiber as a long path length makes the monitor highly sensitive for hexachromium detection. This monitor is specific for hexachromium detection without interference from tri-valence chromium ions. A detection limit of 0.1 ng Cr(VI) ml(-1) was obtained with this simple monitor."
1232083,Sugden and  Martin 2002,"Guanine and 7,8-dihydro-8-oxo-guanine-specific oxidation in DNA by chromium(V)","The hexavalent oxidation state of chromium [Cr(VI)] is a well-established human carcinogen, although the mechanism of cancer induction is currently unknown. Intracellular reduction of Cr(VI) forms Cr(V), which is thought to play a fundamental role in the mechanism of DNA damage by this carcinogen. Two separate pathways of DNA damage, an oxidative pathway and a metal-binding pathway, have been proposed to account for the lesions observed in cell systems. We have used a model Cr(V) complex, N,N-ethylenebis(salicylidene-animato)oxochromium(V) [Cr(V)-Salen], to investigate the oxidative pathway of DNA damage and to elucidate the lesions generated from this oxidation process. Reaction of Cr(V)-Salen with synthetic oligonucleotides produced guanine-specific lesions that were not 8-oxo-2'-deoxyguanosine, based on the inability of iridium(IV) to further oxidize these sites. Oxidation products were identified using a 7,8-dihydro-8-oxo-2'-deoxyguanosine (8-oxo-G) containing oligonucleotide to increase the yields of product for identification by electrospray ionization mass spectrometry. The guanine-based lesions observed by mass spectrometry corresponded to the lesions guanidinohydantoin and spiroiminodihydantoin. The effects of these Cr(V)-Salen-induced lesions on DNA replication fidelity was assayed using a polymerase-based misincorporation assay. These lesions produced G --&gt; T transversion mutations and polymerase stops at levels greater than those observed for 8-oxo-G. These data suggest a model by which chromate can cause DNA damage leading to mutations and cancer.","Guanine and 7,8-dihydro-8-oxo-guanine-specific oxidation in DNA by chromium(V) Abs: The hexavalent oxidation state of chromium [Cr(VI)] is a well-established human carcinogen, although the mechanism of cancer induction is currently unknown. Intracellular reduction of Cr(VI) forms Cr(V), which is thought to play a fundamental role in the mechanism of DNA damage by this carcinogen. Two separate pathways of DNA damage, an oxidative pathway and a metal-binding pathway, have been proposed to account for the lesions observed in cell systems. We have used a model Cr(V) complex, N,N-ethylenebis(salicylidene-animato)oxochromium(V) [Cr(V)-Salen], to investigate the oxidative pathway of DNA damage and to elucidate the lesions generated from this oxidation process. Reaction of Cr(V)-Salen with synthetic oligonucleotides produced guanine-specific lesions that were not 8-oxo-2'-deoxyguanosine, based on the inability of iridium(IV) to further oxidize these sites. Oxidation products were identified using a 7,8-dihydro-8-oxo-2'-deoxyguanosine (8-oxo-G) containing oligonucleotide to increase the yields of product for identification by electrospray ionization mass spectrometry. The guanine-based lesions observed by mass spectrometry corresponded to the lesions guanidinohydantoin and spiroiminodihydantoin. The effects of these Cr(V)-Salen-induced lesions on DNA replication fidelity was assayed using a polymerase-based misincorporation assay. These lesions produced G --&gt; T transversion mutations and polymerase stops at levels greater than those observed for 8-oxo-G. These data suggest a model by which chromate can cause DNA damage leading to mutations and cancer."
1232082,Zhitkovich et al. 2002,Reductive activation with cysteine represents a chromium(III)-dependent pathway in the induction of genotoxicity by carcinogenic chromium(VI),"Induction of DNA damage by carcinogenic hexavalent chromium compounds [Cr(VI)] results from its reduction to lower oxidation states. Reductive metabolism of Cr(VI) generates intermediate Cr(V/IV)species, organic radicals, and finally Cr(III), which forms stable complexes with many biological ligands, including DNA. To determine the biological significance of different reaction products, we examined genotoxic responses and the formation of DNA damage during reduction of Cr(VI) by its biological reducer, cysteine. We have found that cysteine-dependent activation of Cr(VI) led to the formation of Cr-DNA and cysteine-Cr-DNA adducts as well as interstrand DNA cross-links. The yield of binary and ternary DNA adducts was relatively constant at different concentrations of Cr(VI) and averaged approximately 54 and 45%, respectively. Interstrand DNA cross-links accounted on average for 1% of adducts, and their yield was even less significant at low Cr(VI) concentrations. Reduction of Cr(VI) in several commonly used buffers did not induce detectable damage to the sugar-phosphate backbone of DNA. Replication of Cr(VI)-modified plasmids in intact human fibroblasts has shown that cysteine-dependent metabolism of Cr(VI) resulted in the formation of mutagenic and replication-blocking DNA lesions. Selective elimination of Cr-DNA adducts from Cr(VI)-treated plasmids abolished all genotoxic responses, indicating that nonoxidative, Cr(III)-dependent reactions were responsible for the induction of both mutagenicity and replication blockage by Cr(VI). The demonstration of the mutagenic potential of Cr-DNA adducts suggests that these lesions can be explored in the development of specific and mechanistically important biomarkers of exposure to toxic forms of Cr.","Reductive activation with cysteine represents a chromium(III)-dependent pathway in the induction of genotoxicity by carcinogenic chromium(VI) Abs: Induction of DNA damage by carcinogenic hexavalent chromium compounds [Cr(VI)] results from its reduction to lower oxidation states. Reductive metabolism of Cr(VI) generates intermediate Cr(V/IV)species, organic radicals, and finally Cr(III), which forms stable complexes with many biological ligands, including DNA. To determine the biological significance of different reaction products, we examined genotoxic responses and the formation of DNA damage during reduction of Cr(VI) by its biological reducer, cysteine. We have found that cysteine-dependent activation of Cr(VI) led to the formation of Cr-DNA and cysteine-Cr-DNA adducts as well as interstrand DNA cross-links. The yield of binary and ternary DNA adducts was relatively constant at different concentrations of Cr(VI) and averaged approximately 54 and 45%, respectively. Interstrand DNA cross-links accounted on average for 1% of adducts, and their yield was even less significant at low Cr(VI) concentrations. Reduction of Cr(VI) in several commonly used buffers did not induce detectable damage to the sugar-phosphate backbone of DNA. Replication of Cr(VI)-modified plasmids in intact human fibroblasts has shown that cysteine-dependent metabolism of Cr(VI) resulted in the formation of mutagenic and replication-blocking DNA lesions. Selective elimination of Cr-DNA adducts from Cr(VI)-treated plasmids abolished all genotoxic responses, indicating that nonoxidative, Cr(III)-dependent reactions were responsible for the induction of both mutagenicity and replication blockage by Cr(VI). The demonstration of the mutagenic potential of Cr-DNA adducts suggests that these lesions can be explored in the development of specific and mechanistically important biomarkers of exposure to toxic forms of Cr."
1232080,Vilcheck et al. 2002,Fanconi anemia complementation group A cells are hypersensitive to chromium(VI)-induced toxicity,"Fanconi anemia (FA) is an autosomal recessive disorder characterized by diverse developmental abnormalities, progressive bone marrow failure, and a markedly increased incidence of malignancy. FA cells are hypersensitive to DNA cross-linking agents, suggesting a general defect in the repair of DNA cross-links. Some forms of hexavalent chromium [Cr(VI)] are implicated as respiratory carcinogens and induce several types of DNA lesions, including ternary DNA-Cr-DNA interstrand cross-links (Cr-DDC). We hypothesized that human FA complementation group A (FA-A) cells would be hypersensitive to Cr(VI) and Cr(VI)-induced apoptosis. Using phosphatidylserine translocation and caspase-3 activation, human FA-A fibroblasts were found to be markedly hypersensitive to chromium-induced apoptosis compared with CRL-1634 cells, which are normal human foreskin fibroblasts (CRL). The clonogenicity of FA-A cells was also significantly decreased compared with CRL cells after Cr(VI) treatment. There was no significant difference in either Cr(VI) uptake or Cr-DNA adduct formation between FA-A and CRL cells. These results show that FA-A cells are hypersensitive to Cr(VI) and Cr-induced apoptosis and that this hypersensitivity is not due to increased Cr(VI) uptake or increased Cr-DNA adduct formation. The results also suggest that Cr-DDC may be proapoptotic lesions. These results are the first to show that FA cells are hypersensitive to an environmentally relevant DNA cross-linking agent.","Fanconi anemia complementation group A cells are hypersensitive to chromium(VI)-induced toxicity Abs: Fanconi anemia (FA) is an autosomal recessive disorder characterized by diverse developmental abnormalities, progressive bone marrow failure, and a markedly increased incidence of malignancy. FA cells are hypersensitive to DNA cross-linking agents, suggesting a general defect in the repair of DNA cross-links. Some forms of hexavalent chromium [Cr(VI)] are implicated as respiratory carcinogens and induce several types of DNA lesions, including ternary DNA-Cr-DNA interstrand cross-links (Cr-DDC). We hypothesized that human FA complementation group A (FA-A) cells would be hypersensitive to Cr(VI) and Cr(VI)-induced apoptosis. Using phosphatidylserine translocation and caspase-3 activation, human FA-A fibroblasts were found to be markedly hypersensitive to chromium-induced apoptosis compared with CRL-1634 cells, which are normal human foreskin fibroblasts (CRL). The clonogenicity of FA-A cells was also significantly decreased compared with CRL cells after Cr(VI) treatment. There was no significant difference in either Cr(VI) uptake or Cr-DNA adduct formation between FA-A and CRL cells. These results show that FA-A cells are hypersensitive to Cr(VI) and Cr-induced apoptosis and that this hypersensitivity is not due to increased Cr(VI) uptake or increased Cr-DNA adduct formation. The results also suggest that Cr-DDC may be proapoptotic lesions. These results are the first to show that FA cells are hypersensitive to an environmentally relevant DNA cross-linking agent."
1232079,Viti et al. 2003,Characterization of Cr(VI)-resistant bacteria isolated from chromium-contaminated soil by tannery activity,"Bacterial strains, previously isolated from a chromium-polluted soil, were identified on the basis of Gram reaction and biochemical characteristics (Biolog system). Moreover, chromate MICs, chromate reduction capability, multiple heavy metal tolerance, and antibiotic susceptibility were tested for each isolate. All strains but one were Gram-positive and resistant to high concentrations of chromate. The most Cr(VI)-resistant isolate (22m M) was identified as Corynebacterium hoagii. All Cr(VI)-resistant strains except the isolate ChrC20 were capable of catalyzing the reduction of Cr(VI) to Cr(III), a less toxic and less water-soluble form of chromium. The only isolate Cr(VI)-sensitive, attributed to the Pseudomonas genus, also exhibited Cr(VI)-reduction. Isolates were also screened for the presence of plasmid DNA. The strains ChrC20 and ChrB20 harbored one and two plasmids of high molecular mass, respectively. This approach permitted selection of some bacterial strains, which could be used for bioremediation of Cr(VI)-polluted environments.","Characterization of Cr(VI)-resistant bacteria isolated from chromium-contaminated soil by tannery activity Abs: Bacterial strains, previously isolated from a chromium-polluted soil, were identified on the basis of Gram reaction and biochemical characteristics (Biolog system). Moreover, chromate MICs, chromate reduction capability, multiple heavy metal tolerance, and antibiotic susceptibility were tested for each isolate. All strains but one were Gram-positive and resistant to high concentrations of chromate. The most Cr(VI)-resistant isolate (22m M) was identified as Corynebacterium hoagii. All Cr(VI)-resistant strains except the isolate ChrC20 were capable of catalyzing the reduction of Cr(VI) to Cr(III), a less toxic and less water-soluble form of chromium. The only isolate Cr(VI)-sensitive, attributed to the Pseudomonas genus, also exhibited Cr(VI)-reduction. Isolates were also screened for the presence of plasmid DNA. The strains ChrC20 and ChrB20 harbored one and two plasmids of high molecular mass, respectively. This approach permitted selection of some bacterial strains, which could be used for bioremediation of Cr(VI)-polluted environments."
1232078,Wei et al. 2002,Thermal stabilization of chromium(VI) in kaolin,"Reduction of Cr(VI) by heating may be a useful detoxification mechanism for thermal immobilization. Using X-ray absorption spectroscopy, the change of speciation of chromium in 105 degrees C dried 3.7% Cr(VI)-sorbed kaolin further heated at 500, 900, or 1100 degrees C was studied. The 105 degrees C dried 3.7% Cr(VI)-sorbed kaolin sample was prepared by mixing 1.5 L of 0.257 M CrO3 solution (pH 0.71) with 0.5 kg of kaolin powder for 48 h, and then the slurry was heated (dried) at 105 degrees C until a constant weight was reached. The toxicity characteristic leaching procedure method was used to determine the percentage of leached chromium from all heated samples. In all 500-900 degrees C heated Cr(VI)-sorbed kaolin samples, Cr2O3 transformed from the hydrated Cr(VI) by a 4-h heat application was identified by the X-ray absorption near edge structure and extended X-ray absorption fine structure (EXAFS) spectroscopy as the key species that is leaching-resistant due to its low solubility. For the 1100 degrees C heated Cr(VI)-sorbed kaolin sample, the Fourier transform of its EXAFS spectrum indicates that the intensity of the peaks at 2.45 (Cr-Cr shell of Cr2O3) and 5.00 A (Cr-Cr and Cr-O shells of Cr2O3) without phase shift correction is either relatively smaller or disappearing, compared with that of the 500-900 degrees C heated Cr(VI)-sorbed kaolin samples. It is suggested that chromium octahedra were bridged to silica tetrahedra and incorporated in minerals formed at 1100 degrees C, such as mullite or sillimanite, since these phases were detected by XRD. Cr of this form is not easily leached.","Thermal stabilization of chromium(VI) in kaolin Abs: Reduction of Cr(VI) by heating may be a useful detoxification mechanism for thermal immobilization. Using X-ray absorption spectroscopy, the change of speciation of chromium in 105 degrees C dried 3.7% Cr(VI)-sorbed kaolin further heated at 500, 900, or 1100 degrees C was studied. The 105 degrees C dried 3.7% Cr(VI)-sorbed kaolin sample was prepared by mixing 1.5 L of 0.257 M CrO3 solution (pH 0.71) with 0.5 kg of kaolin powder for 48 h, and then the slurry was heated (dried) at 105 degrees C until a constant weight was reached. The toxicity characteristic leaching procedure method was used to determine the percentage of leached chromium from all heated samples. In all 500-900 degrees C heated Cr(VI)-sorbed kaolin samples, Cr2O3 transformed from the hydrated Cr(VI) by a 4-h heat application was identified by the X-ray absorption near edge structure and extended X-ray absorption fine structure (EXAFS) spectroscopy as the key species that is leaching-resistant due to its low solubility. For the 1100 degrees C heated Cr(VI)-sorbed kaolin sample, the Fourier transform of its EXAFS spectrum indicates that the intensity of the peaks at 2.45 (Cr-Cr shell of Cr2O3) and 5.00 A (Cr-Cr and Cr-O shells of Cr2O3) without phase shift correction is either relatively smaller or disappearing, compared with that of the 500-900 degrees C heated Cr(VI)-sorbed kaolin samples. It is suggested that chromium octahedra were bridged to silica tetrahedra and incorporated in minerals formed at 1100 degrees C, such as mullite or sillimanite, since these phases were detected by XRD. Cr of this form is not easily leached."
1232077,Shi and  Jiang 2002,Antioxidant properties of apple juice and its protection against Cr(VI)-induced cellular injury,"Reactive oxygen species (ROS) have been shown to cause a broad spectrum of damage to the biological system. ROS-mediated reactions are believed to play a key role in Cr(VI)-induced carcinogenesis. Using electron spin resonance (ESR) spin trapping, the present study shows that apple juice efficiently scavenged hydroxyl radicals generated by Cr(VI) reduction catalyzed byglutathione reductase/NADPH. Apple juice reduced Cr(VI)-induced lipid peroxidation, DNA damage, cell apoptosis, and NF-kappaB activation in human lung epithelial A549 cells. The lipid peroxidation was measured by a colorimetric assay, DNA damage by single cell gel electrophoresis assay, induction of cell apoptosis by flow cytometry, and activation of NF-kappaB by luciferase assay. The results show that through its antioxidant properties, apple juice can protect Cr(VI)-induced cellular injury and may help reduce its carcinogenic potentiaL","Antioxidant properties of apple juice and its protection against Cr(VI)-induced cellular injury Abs: Reactive oxygen species (ROS) have been shown to cause a broad spectrum of damage to the biological system. ROS-mediated reactions are believed to play a key role in Cr(VI)-induced carcinogenesis. Using electron spin resonance (ESR) spin trapping, the present study shows that apple juice efficiently scavenged hydroxyl radicals generated by Cr(VI) reduction catalyzed byglutathione reductase/NADPH. Apple juice reduced Cr(VI)-induced lipid peroxidation, DNA damage, cell apoptosis, and NF-kappaB activation in human lung epithelial A549 cells. The lipid peroxidation was measured by a colorimetric assay, DNA damage by single cell gel electrophoresis assay, induction of cell apoptosis by flow cytometry, and activation of NF-kappaB by luciferase assay. The results show that through its antioxidant properties, apple juice can protect Cr(VI)-induced cellular injury and may help reduce its carcinogenic potentiaL"
1232076,Kozlowski and  Walkowiak 2002,Removal of chromium(VI) from aqueous solutions by polymer inclusion membranes,"The transport through polymer inclusion membranes (PIMs) was found as the effective and selective method of chromium(VI) anions removal from chloride acidic aqueous solutions. The optimal PIMs content was as follows: 41 wt% of cellulose triacetate as the support, 23 wt% of tri-n-octylamine as the ionic carrier, and 36 wt% of o-nitrophenyl pentyl ether as the plasticizer. The results obtained show a linear decrease of permeability coefficient and initial flux values with source phase pH increase. Also linear decrease of initial flux in log-log scale with chromium(VI) concentration increase was observed. Value of slope of this relationship was found to be 0.96 which indicates a first order of chromium(VI) reaction with tri-n-octylamine at membrane/aqueous source interface. Transport of chromium(VI) through PIMs reduces the concentration of chromium(VI) in source aqueous phase from 1.0 to 0.0028 ppm, which is below permissible limit in drinking water in Poland. Competitive transport of chromium(VI), cadmium(II), zinc(II), and iron(III) from acidic aqueous solution across PIMs was found to be efficient for chromium(VI) (99%), and cadmium(II) (99%).","Removal of chromium(VI) from aqueous solutions by polymer inclusion membranes Abs: The transport through polymer inclusion membranes (PIMs) was found as the effective and selective method of chromium(VI) anions removal from chloride acidic aqueous solutions. The optimal PIMs content was as follows: 41 wt% of cellulose triacetate as the support, 23 wt% of tri-n-octylamine as the ionic carrier, and 36 wt% of o-nitrophenyl pentyl ether as the plasticizer. The results obtained show a linear decrease of permeability coefficient and initial flux values with source phase pH increase. Also linear decrease of initial flux in log-log scale with chromium(VI) concentration increase was observed. Value of slope of this relationship was found to be 0.96 which indicates a first order of chromium(VI) reaction with tri-n-octylamine at membrane/aqueous source interface. Transport of chromium(VI) through PIMs reduces the concentration of chromium(VI) in source aqueous phase from 1.0 to 0.0028 ppm, which is below permissible limit in drinking water in Poland. Competitive transport of chromium(VI), cadmium(II), zinc(II), and iron(III) from acidic aqueous solution across PIMs was found to be efficient for chromium(VI) (99%), and cadmium(II) (99%)."
1232075,Tseng and  Bielefeldt 2002,Low-temperature chromium(VI) biotransformation in soil with varying electron acceptors,"Effective and low-cost strategies for remediating chromium (Cr)-contaminated soil are needed. Chromium(VI) leaching from contaminated soil into ground water and surface water threatens water supplies and the environment. This study tested indigenous Cr(VI) microbial transformation in batch systems at 10 degrees C in the presence of various electron acceptors. The effects of carbon addition, spiked Cr(VI), and mixing highly contaminated soil with less contaminated soil were investigated. The results indicated that Cr(VI) can be biotransformed in the presence of different electron acceptors including oxygen, nitrate, sulfate, and iron. Sugar addition had the greatest effect on enhancing Cr(VI) removal. Less dissolved organic carbon (DOC) was consumed per amount of Cr(VI) transformed under anaerobic conditions [0.8-93 mg DOC/mg Cr(VI)] compared with aerobic conditions [1.4-265 mg DOC/mg Cr(VI)]. Toxicity of high concentrations (&lt; 160 mg/L) of spiked Cr(VI) were not evident. At Cr(VI) concentrations &gt; 40 mg/L, aerobic conditions promoted faster Cr(VI) reduction than anaerobic conditions with nitrate or sulfate present. Biotransformation of Cr(VI) in highly contaminated soil (22,000 mg Cr/kg) was facilitated by mixing with less-contaminated soil. The study results provide a framework for evaluating indigenous Cr(VI) microbial transformation and enhance the ability to develop strategies for soil treatment.","Low-temperature chromium(VI) biotransformation in soil with varying electron acceptors Abs: Effective and low-cost strategies for remediating chromium (Cr)-contaminated soil are needed. Chromium(VI) leaching from contaminated soil into ground water and surface water threatens water supplies and the environment. This study tested indigenous Cr(VI) microbial transformation in batch systems at 10 degrees C in the presence of various electron acceptors. The effects of carbon addition, spiked Cr(VI), and mixing highly contaminated soil with less contaminated soil were investigated. The results indicated that Cr(VI) can be biotransformed in the presence of different electron acceptors including oxygen, nitrate, sulfate, and iron. Sugar addition had the greatest effect on enhancing Cr(VI) removal. Less dissolved organic carbon (DOC) was consumed per amount of Cr(VI) transformed under anaerobic conditions [0.8-93 mg DOC/mg Cr(VI)] compared with aerobic conditions [1.4-265 mg DOC/mg Cr(VI)]. Toxicity of high concentrations (&lt; 160 mg/L) of spiked Cr(VI) were not evident. At Cr(VI) concentrations &gt; 40 mg/L, aerobic conditions promoted faster Cr(VI) reduction than anaerobic conditions with nitrate or sulfate present. Biotransformation of Cr(VI) in highly contaminated soil (22,000 mg Cr/kg) was facilitated by mixing with less-contaminated soil. The study results provide a framework for evaluating indigenous Cr(VI) microbial transformation and enhance the ability to develop strategies for soil treatment."
1232074,Lapuma and  Rhodes 2002,Chromate content versus particle size for aircraft paints,"Many industries rely on the corrosion inhibiting properties of chromate-containing primer paints to protect metal from oxidation. However, chromate contains hexavalent chromium (Cr(6+)), a known human carcinogen. The concentration of Cr(6+) as a function of paint particle size has important implications to worker health and environmental release from paint facilities. This research examines Cr(6+) content as a function of particle size for three types of aircraft primer paints: solvent-based epoxy-polyamide, water-based epoxy-polyamide, and solvent-based polyurethane. Cascade impactors were used to collect and separate paint particles based on their aerodynamic diameter, from 0.7 to 34.1 microm. The mass of the dry paint collected at each stage was determined and an atomic absorption spectrometer was used to analyze for Cr(6+) content. For all three paints, particles less than 7.0 microm contained disproportionately less Cr(6+) per mass of dry paint than larger particles, and the Cr(6+)concentration decreased substantially as particle size decreased. The smallest particles, 0.7 to 1.0 microm, contained approximately 10% of the Cr(6+) content, per mass of dry paint, compared to particles larger than 7.0 microm. The paint gun settings of air to paint ratio was found to have no influence on the Cr(6+) bias.","Chromate content versus particle size for aircraft paints Abs: Many industries rely on the corrosion inhibiting properties of chromate-containing primer paints to protect metal from oxidation. However, chromate contains hexavalent chromium (Cr(6+)), a known human carcinogen. The concentration of Cr(6+) as a function of paint particle size has important implications to worker health and environmental release from paint facilities. This research examines Cr(6+) content as a function of particle size for three types of aircraft primer paints: solvent-based epoxy-polyamide, water-based epoxy-polyamide, and solvent-based polyurethane. Cascade impactors were used to collect and separate paint particles based on their aerodynamic diameter, from 0.7 to 34.1 microm. The mass of the dry paint collected at each stage was determined and an atomic absorption spectrometer was used to analyze for Cr(6+) content. For all three paints, particles less than 7.0 microm contained disproportionately less Cr(6+) per mass of dry paint than larger particles, and the Cr(6+)concentration decreased substantially as particle size decreased. The smallest particles, 0.7 to 1.0 microm, contained approximately 10% of the Cr(6+) content, per mass of dry paint, compared to particles larger than 7.0 microm. The paint gun settings of air to paint ratio was found to have no influence on the Cr(6+) bias."
1232073,Lapuma et al. 2002,Chromate dissociation from three types of paint particles,"Chromate-containing primer paints are used to inhibit corrosion on metal surfaces. Though chromate contains hexavalent chromium (Cr(6+)), a human carcinogen, there is little epidemiological evidence of increased lung cancer among spray painters. One reason may be that the paint matrix hinders the release of Cr(6+) from the paint particle during the time that the particle is within the lungs. This study measures the mass of Cr(6+) released from particles originating from three types of paint particles: solvent-borne epoxy, water-borne epoxy, and polyurethane. Impingers were used to collect paint particles into water and particles were held in the water at rest for 1 and 24 h residence times. Particles were then separated from the water by centrifugation. The supernatant was tested for dissolved Cr(6+), which was compared to the total Cr(6+) (dissolved Cr(6+) plus Cr(6+) in particles). The mean fractions of Cr(6+) released into the water after 1 and 24 hours for each primer averaged: 70 and 85 (solvent epoxy), 74 and 84% (water epoxy), and 94 and 95% (polyurethane). Correlations between particle size and the fraction of Cr(6+) released indicate that smaller particles (&lt;5 microm) release a larger fraction of Cr(6+) versus larger particles (&gt;5 microm).","Chromate dissociation from three types of paint particles Abs: Chromate-containing primer paints are used to inhibit corrosion on metal surfaces. Though chromate contains hexavalent chromium (Cr(6+)), a human carcinogen, there is little epidemiological evidence of increased lung cancer among spray painters. One reason may be that the paint matrix hinders the release of Cr(6+) from the paint particle during the time that the particle is within the lungs. This study measures the mass of Cr(6+) released from particles originating from three types of paint particles: solvent-borne epoxy, water-borne epoxy, and polyurethane. Impingers were used to collect paint particles into water and particles were held in the water at rest for 1 and 24 h residence times. Particles were then separated from the water by centrifugation. The supernatant was tested for dissolved Cr(6+), which was compared to the total Cr(6+) (dissolved Cr(6+) plus Cr(6+) in particles). The mean fractions of Cr(6+) released into the water after 1 and 24 hours for each primer averaged: 70 and 85 (solvent epoxy), 74 and 84% (water epoxy), and 94 and 95% (polyurethane). Correlations between particle size and the fraction of Cr(6+) released indicate that smaller particles (&lt;5 microm) release a larger fraction of Cr(6+) versus larger particles (&gt;5 microm)."
1232071,Chmielnicka et al. 2002,Essential elements as early indicators of hexavalent chromium nephrotoxicity,"The kidney is the appropriate critical organ for indicating chronic exposure to chromium compounds. The present work investigates the effect of dose-dependent hexavalent chromium concentration in various tissues of rats, the disturbances in metabolism of zinc and copper in liver and kidney, and histopathological changes in kidneys. White Wistar rats were used. Animals were injected intraperitoneally at a dose of 0.5 and 5 mg Cr/kg as K2CrO4. The animals were sacrificed after single and repeated doses at 24 h after the last injection. Disturbances in the metabolism of zinc and copper in the kidney of rats occur when the concentration of chromium in this organ attains about 30 microg Cr/g. An increase in urinary output of these essential metals is a more sensitive indicator of nephrotoxicity than ultrastructural damage of kidney.","Essential elements as early indicators of hexavalent chromium nephrotoxicity Abs: The kidney is the appropriate critical organ for indicating chronic exposure to chromium compounds. The present work investigates the effect of dose-dependent hexavalent chromium concentration in various tissues of rats, the disturbances in metabolism of zinc and copper in liver and kidney, and histopathological changes in kidneys. White Wistar rats were used. Animals were injected intraperitoneally at a dose of 0.5 and 5 mg Cr/kg as K2CrO4. The animals were sacrificed after single and repeated doses at 24 h after the last injection. Disturbances in the metabolism of zinc and copper in the kidney of rats occur when the concentration of chromium in this organ attains about 30 microg Cr/g. An increase in urinary output of these essential metals is a more sensitive indicator of nephrotoxicity than ultrastructural damage of kidney."
1232070,Dirilgen and  Do?an 2002,Speciation of chromium in the presence of copper and zinc and their combined toxicity,"Speciation of chromium has attracted a great deal of interest in view of the toxic properties of Cr(6+) compared with the much less toxic Cr(3+). A freshwater plant, duckweed which is uniquely suitable for aquatic toxicity tests is utilized to study the growth responses and accumulation of chromium in the presence of copper and zinc. Speciation analysis was carried out by using differently activated alumina. Metal ion concentrations in the plant were determined by FAA spectrometry. Results of the present study revealed that the oxidation state of chromium as well as its concentration in media controlled the growth and the metal accumulation in duckweed. Regarding this, Lemna minor (common duckweed species) accumulated Cr(3+) in smaller quantities and it resulted in relatively larger growth responses, whereas Cr(6+) was accumulated in larger quantities and it yielded relatively smaller growth responses. Different types of metal interactions among chromium, copper, and zinc ions were evident. These interactions were classified as synergistic, antagonistic, and additive and they were strictly dependent on the oxidation state of the chromium ion.","Speciation of chromium in the presence of copper and zinc and their combined toxicity Abs: Speciation of chromium has attracted a great deal of interest in view of the toxic properties of Cr(6+) compared with the much less toxic Cr(3+). A freshwater plant, duckweed which is uniquely suitable for aquatic toxicity tests is utilized to study the growth responses and accumulation of chromium in the presence of copper and zinc. Speciation analysis was carried out by using differently activated alumina. Metal ion concentrations in the plant were determined by FAA spectrometry. Results of the present study revealed that the oxidation state of chromium as well as its concentration in media controlled the growth and the metal accumulation in duckweed. Regarding this, Lemna minor (common duckweed species) accumulated Cr(3+) in smaller quantities and it resulted in relatively larger growth responses, whereas Cr(6+) was accumulated in larger quantities and it yielded relatively smaller growth responses. Different types of metal interactions among chromium, copper, and zinc ions were evident. These interactions were classified as synergistic, antagonistic, and additive and they were strictly dependent on the oxidation state of the chromium ion."
1232069,O'Brien et al. 2002,Effects of hexavalent chromium on the survival and cell cycle distribution of DNA repair-deficient S. cerevisiae,"A broad spectrum of genetic damage results from exposure to hexavalent chromium. These lesions can result in DNA and RNA polymerase arrest, chromosomal aberrations, point mutations and deletions. Because of the complexity of Cr genotoxicity, the repair of Cr(VI)-induced DNA damage is poorly understood. Therefore, our aim was to investigate the sensitivities of DNA repair-deficient Saccharomyces cerevisiae strains to Cr(VI)-induced growth inhibition and lethality. Wild-type, translesion synthesis (rev3) and excision repair (apn1, ntg1, ntg2, rad1) mutants exhibited similar survival following Cr(VI) treatment (0-50mM) and underwent at least one population doubling within 2-4h post-treatment. The simultaneous loss of several excision repair genes (apn1 rad1 ntg1 ntg2) led to slower growth after Cr(VI) exposure (10mM) manifested as an initial delay in S phase progression. Higher concentrations of Cr(VI) (25mM) resulted in a prolonged transit through S phase in every strain tested. A G(2)/M arrest was evident within 1-2h after Cr(VI) treatment (10mM) in all strains and cells subsequently divided after this transient delay. In contrast to all other strains, only recombination-deficient (rad52, rad52 rev3) yeast were markedly hypersensitive towards Cr(VI) lethality. RAD52 mutant strains (rad52, rad52 rev3) also exhibited a significant delay (&gt;6h) in the resumption of replication after Cr(VI) exposure which was related to the immediate and apparently terminal arrest of these yeast in G(2)/M after Cr(VI) treatment. These results, taken together with the recombinogenic effects of Cr(VI) in yeast containing a functional RAD52 gene, suggest that RAD52-mediated recombination is critical for the normal processing of lethal Cr-induced genetic lesions and exit from G(2) arrest. Furthermore, only the combined inactivation of multiple excision repair genes affects cell growth after Cr(VI) treatment.","Effects of hexavalent chromium on the survival and cell cycle distribution of DNA repair-deficient S. cerevisiae Abs: A broad spectrum of genetic damage results from exposure to hexavalent chromium. These lesions can result in DNA and RNA polymerase arrest, chromosomal aberrations, point mutations and deletions. Because of the complexity of Cr genotoxicity, the repair of Cr(VI)-induced DNA damage is poorly understood. Therefore, our aim was to investigate the sensitivities of DNA repair-deficient Saccharomyces cerevisiae strains to Cr(VI)-induced growth inhibition and lethality. Wild-type, translesion synthesis (rev3) and excision repair (apn1, ntg1, ntg2, rad1) mutants exhibited similar survival following Cr(VI) treatment (0-50mM) and underwent at least one population doubling within 2-4h post-treatment. The simultaneous loss of several excision repair genes (apn1 rad1 ntg1 ntg2) led to slower growth after Cr(VI) exposure (10mM) manifested as an initial delay in S phase progression. Higher concentrations of Cr(VI) (25mM) resulted in a prolonged transit through S phase in every strain tested. A G(2)/M arrest was evident within 1-2h after Cr(VI) treatment (10mM) in all strains and cells subsequently divided after this transient delay. In contrast to all other strains, only recombination-deficient (rad52, rad52 rev3) yeast were markedly hypersensitive towards Cr(VI) lethality. RAD52 mutant strains (rad52, rad52 rev3) also exhibited a significant delay (&gt;6h) in the resumption of replication after Cr(VI) exposure which was related to the immediate and apparently terminal arrest of these yeast in G(2)/M after Cr(VI) treatment. These results, taken together with the recombinogenic effects of Cr(VI) in yeast containing a functional RAD52 gene, suggest that RAD52-mediated recombination is critical for the normal processing of lethal Cr-induced genetic lesions and exit from G(2) arrest. Furthermore, only the combined inactivation of multiple excision repair genes affects cell growth after Cr(VI) treatment."
1232068,Fruchter 2002,In situ treatment of chromium-contaminated groundwater,,In situ treatment of chromium-contaminated groundwater Abs: 
1232067,Singh and  Singh 2002,Influence of dissolved oxygen on aqueous Cr(VI) removal by ferrous ion,"Hexavalent chromium [Cr(VI)] is a highly toxic and carcnogenic pollutant, introduced to the environment due to several industrial activities. Ferrous iron (Fe(II)], an important natural reductant of the Cr(VI), and its release from iron-bearing materials is now becoming a viable alternative for transforming Cr(VI) to the relatively non toxic trivalent form of chromium [Cr(III)]. Cr(VI) removal by ferrous ion at different pH is widely discussed in the literature but the influence of dissolved oxygen on the Cr(VI) removal with respect to pH, is still a contradictory subject. In the present study a systematic approach has been made to estimate the Cr(VI) removal by ferrous ion in oxygen-free and oxygen-containing aqueous solutions of pH 3 to 7. Quantitative analysis results suggest that the influence of dissolved oxygen on the Cr(VI) reduction starts at pH 4. Though, its effect appears to be in significant up to pH 6, becomes quite pronounced at pH 7 because nearly 10 to 12% less removal of the Cr(VI) was observed in the presence of the stoichiometric requirement of three equivalents of Fe(II) in oxygenated solution of pH 7. This was evidenced by carrying detailed spectrophotometric absorption measurements of the Cr(VI) in the presence of Fe(II) in its different equivalent ratios in oxygenated and deoxygenated solutions.","Influence of dissolved oxygen on aqueous Cr(VI) removal by ferrous ion Abs: Hexavalent chromium [Cr(VI)] is a highly toxic and carcnogenic pollutant, introduced to the environment due to several industrial activities. Ferrous iron (Fe(II)], an important natural reductant of the Cr(VI), and its release from iron-bearing materials is now becoming a viable alternative for transforming Cr(VI) to the relatively non toxic trivalent form of chromium [Cr(III)]. Cr(VI) removal by ferrous ion at different pH is widely discussed in the literature but the influence of dissolved oxygen on the Cr(VI) removal with respect to pH, is still a contradictory subject. In the present study a systematic approach has been made to estimate the Cr(VI) removal by ferrous ion in oxygen-free and oxygen-containing aqueous solutions of pH 3 to 7. Quantitative analysis results suggest that the influence of dissolved oxygen on the Cr(VI) reduction starts at pH 4. Though, its effect appears to be in significant up to pH 6, becomes quite pronounced at pH 7 because nearly 10 to 12% less removal of the Cr(VI) was observed in the presence of the stoichiometric requirement of three equivalents of Fe(II) in oxygenated solution of pH 7. This was evidenced by carrying detailed spectrophotometric absorption measurements of the Cr(VI) in the presence of Fe(II) in its different equivalent ratios in oxygenated and deoxygenated solutions."
1232065,Bolan et al. 2003,Effects of organic amendments on the reduction and phytoavailability of chromate in mineral soil,"In this study, seven organic amendments (biosolid compost, farm yard manure, fish manure, horse manure, spent mushroom, pig manure, and poultry manure) were investigated for their effects on the reduction of hexavalent chromium [chromate, Cr(VI)] in a mineral soil (Manawatu sandy soil) low in organic matter content. Addition of organic amendments enhanced the rate of reduction of Cr(VI) to Cr(III) in the soil. At the same level of total organic carbon addition, there was a significant difference in the extent of Cr(VI) reduction among the soils treated with organic amendments. There was, however, a significant positive linear relationship between the extent of Cr(VI) reduction and the amount of dissolved organic carbon in the soil. The effect of biosolid compost on the uptake of Cr(VI) from the soil, treated with various levels of Cr(VI) (0-1200 mg Cr kg(-1) soil), was examined with mustard (Brassica juncea L.) plants. Increasing addition of Cr(VI) increased Cr concentration in plants, resulting in decreased plant growth (i.e., phytotoxicity). Addition of the biosolid compost was effective in reducing the phytotoxicity of Cr(VI). The redistribution of Cr(VI) in various soil components was evaluated by a sequential fractionation scheme. In the unamended soil, the concentration of Cr was higher in the organic-bound, oxide-bound, and residual fractions than in the soluble and exchangeable fractions. Addition of organic amendments also decreased the concentration of the soluble and exchangeable fractions but especially increased the organic-bound fraction in soil.","Effects of organic amendments on the reduction and phytoavailability of chromate in mineral soil Abs: In this study, seven organic amendments (biosolid compost, farm yard manure, fish manure, horse manure, spent mushroom, pig manure, and poultry manure) were investigated for their effects on the reduction of hexavalent chromium [chromate, Cr(VI)] in a mineral soil (Manawatu sandy soil) low in organic matter content. Addition of organic amendments enhanced the rate of reduction of Cr(VI) to Cr(III) in the soil. At the same level of total organic carbon addition, there was a significant difference in the extent of Cr(VI) reduction among the soils treated with organic amendments. There was, however, a significant positive linear relationship between the extent of Cr(VI) reduction and the amount of dissolved organic carbon in the soil. The effect of biosolid compost on the uptake of Cr(VI) from the soil, treated with various levels of Cr(VI) (0-1200 mg Cr kg(-1) soil), was examined with mustard (Brassica juncea L.) plants. Increasing addition of Cr(VI) increased Cr concentration in plants, resulting in decreased plant growth (i.e., phytotoxicity). Addition of the biosolid compost was effective in reducing the phytotoxicity of Cr(VI). The redistribution of Cr(VI) in various soil components was evaluated by a sequential fractionation scheme. In the unamended soil, the concentration of Cr was higher in the organic-bound, oxide-bound, and residual fractions than in the soluble and exchangeable fractions. Addition of organic amendments also decreased the concentration of the soluble and exchangeable fractions but especially increased the organic-bound fraction in soil."
1232064,Oliver et al. 2003,Microbial reduction of hexavalent chromium under vadose zone conditions,"Hexavalent chromium [Cr(VI)] is a common contaminant associated with nuclear reactors and fuel processing. Improper disposal at facilities in and and semiarid regions has contaminated underlying vadose zones and aquifers. The objectives of this study were to assess the potential for immobilizing Cr(VI) using a native microbial community to reduce soluble Cr(VI) to insoluble Cr(III) under conditions similar to those in the vadose zone, and to evaluate the potential for enhancing biological Cr(VI) reduction through nutrient addition. Batch microcosm and unsaturated flow column experiments were performed. Native microbial communities in subsurface sediments with no prior Cr(VI) exposure were shown to be capable of Cr(VI) reduction. In both the batch and column experiments, Cr(VI) reduction and loss from the aqueous phase were enhanced by adding high levels of both nitrate (NO3-) and organic C (molasses). Nutrient amendments resulted in up to 87% reduction of the initial 67 mg L(-1) Cr(VI) in an unsaturated batch experiment. Molasses and nitrate additions to 15 cm long unsaturated flow columns receiving 65 mg L(-1) Cr(VI) resulted in microbially mediated reduction and immobilization of 10% of the Cr during a 45-d experiment. All of the immobilized Cr was in the form of Cr(III), as shown by XANES analysis. This suggests that biostimulation of microbial Cr(VI) reduction in vadose zones by nutrient amendment is a promising strategy, and that immobilization of close to 100% of Cr contamination could be achieved in a thick vadose zone with longer flow paths and longer contact times than in this experiment.","Microbial reduction of hexavalent chromium under vadose zone conditions Abs: Hexavalent chromium [Cr(VI)] is a common contaminant associated with nuclear reactors and fuel processing. Improper disposal at facilities in and and semiarid regions has contaminated underlying vadose zones and aquifers. The objectives of this study were to assess the potential for immobilizing Cr(VI) using a native microbial community to reduce soluble Cr(VI) to insoluble Cr(III) under conditions similar to those in the vadose zone, and to evaluate the potential for enhancing biological Cr(VI) reduction through nutrient addition. Batch microcosm and unsaturated flow column experiments were performed. Native microbial communities in subsurface sediments with no prior Cr(VI) exposure were shown to be capable of Cr(VI) reduction. In both the batch and column experiments, Cr(VI) reduction and loss from the aqueous phase were enhanced by adding high levels of both nitrate (NO3-) and organic C (molasses). Nutrient amendments resulted in up to 87% reduction of the initial 67 mg L(-1) Cr(VI) in an unsaturated batch experiment. Molasses and nitrate additions to 15 cm long unsaturated flow columns receiving 65 mg L(-1) Cr(VI) resulted in microbially mediated reduction and immobilization of 10% of the Cr during a 45-d experiment. All of the immobilized Cr was in the form of Cr(III), as shown by XANES analysis. This suggests that biostimulation of microbial Cr(VI) reduction in vadose zones by nutrient amendment is a promising strategy, and that immobilization of close to 100% of Cr contamination could be achieved in a thick vadose zone with longer flow paths and longer contact times than in this experiment."
1232063,Quievryn et al. 2003,Genotoxicity and mutagenicity of chromium(VI)/ascorbate-generated DNA adducts in human and bacterial cells,"Reduction of carcinogenic Cr(VI) by vitamin C generates ascorbate-Cr(III)-DNA cross-links, binary Cr(III)-DNA adducts, and can potentially cause oxidative DNA damage by intermediate reaction products. Here, we examined the mutational spectrum and the importance of different forms of DNA damage in genotoxicity and mutagenicity of Cr(VI) activated by physiological concentrations of ascorbate. Reduction of Cr(VI) led to a dose-dependent formation of both mutagenic and replication-blocking DNA lesions as detected by propagation of the pSP189 plasmids in human fibroblasts. Disruption of Cr-DNA binding abolished mutagenic responses and normalized the yield of replicated plasmids, indicating that Cr-DNA adducts were responsible for both mutagenicity and genotoxicity of Cr(VI). The absence of DNA breaks and abasic sites confirmed the lack of a significant production of hydroxyl radicals and Cr(V)-peroxo complexes in Cr(VI)-ascorbate reactions. Ascorbate-Cr(III)-DNA cross-links were much more mutagenic than smaller Cr(III)-DNA adducts and accounted for more than 90% of Cr(VI) mutagenicity. Ternary adducts were also several times more potent in the inhibition of replication than binary complexes. The Cr(VI)-induced mutational spectrum consisted of an approximately equal number of deletions and G/C-targeted point mutations (51% G/C --&gt; T/A and 30% G/C --&gt; A/T). In Escherichia coli cells, Cr(VI)-induced DNA adducts were only highly genotoxic but not mutagenic under either normal or SOS-induced conditions. Lower toxicity and high mutagenicity of ascorbate-Cr(III)-DNA adducts in human cells may result from the recruitment of an error-prone bypass DNA polymerase(s) to the stalled replication forks. Our results suggest that phosphotriester-type DNA adducts could play a more important role in human than bacterial mutagenesis.","Genotoxicity and mutagenicity of chromium(VI)/ascorbate-generated DNA adducts in human and bacterial cells Abs: Reduction of carcinogenic Cr(VI) by vitamin C generates ascorbate-Cr(III)-DNA cross-links, binary Cr(III)-DNA adducts, and can potentially cause oxidative DNA damage by intermediate reaction products. Here, we examined the mutational spectrum and the importance of different forms of DNA damage in genotoxicity and mutagenicity of Cr(VI) activated by physiological concentrations of ascorbate. Reduction of Cr(VI) led to a dose-dependent formation of both mutagenic and replication-blocking DNA lesions as detected by propagation of the pSP189 plasmids in human fibroblasts. Disruption of Cr-DNA binding abolished mutagenic responses and normalized the yield of replicated plasmids, indicating that Cr-DNA adducts were responsible for both mutagenicity and genotoxicity of Cr(VI). The absence of DNA breaks and abasic sites confirmed the lack of a significant production of hydroxyl radicals and Cr(V)-peroxo complexes in Cr(VI)-ascorbate reactions. Ascorbate-Cr(III)-DNA cross-links were much more mutagenic than smaller Cr(III)-DNA adducts and accounted for more than 90% of Cr(VI) mutagenicity. Ternary adducts were also several times more potent in the inhibition of replication than binary complexes. The Cr(VI)-induced mutational spectrum consisted of an approximately equal number of deletions and G/C-targeted point mutations (51% G/C --&gt; T/A and 30% G/C --&gt; A/T). In Escherichia coli cells, Cr(VI)-induced DNA adducts were only highly genotoxic but not mutagenic under either normal or SOS-induced conditions. Lower toxicity and high mutagenicity of ascorbate-Cr(III)-DNA adducts in human cells may result from the recruitment of an error-prone bypass DNA polymerase(s) to the stalled replication forks. Our results suggest that phosphotriester-type DNA adducts could play a more important role in human than bacterial mutagenesis."
1232061,Juturu and  Komorowski 2003,Chromium compounds: cytotoxicity and carcinogenesis,,Chromium compounds: cytotoxicity and carcinogenesis Abs: 
1232060,Arias and  Tebo 2003,Cr(VI) reduction by sulfidogenic and nonsulfidogenic microbial consortia,"In time course experiments, bacterial community compositions were compared between a sulfidogenic and two nonsulfidogenic Cr(VI)-reducing consortia enriched from metal-contaminated sediments. The consortia were subjected to 0 and 0.85 mM or 1.35 mM Cr(VI), and Cr(VI) reduction, growth, and denaturing gradient gel electrophoresis profiles of PCR products of small-subunit (16S) ribosomal genes were compared. Results showed that although Cr(VI) was completely reduced by the three consortia, Cr(VI) inhibited cell growth, with sulfate-reducing bacteria being particularly sensitive to Cr(VI) toxicity relative to other bacteria in the consortia.","Cr(VI) reduction by sulfidogenic and nonsulfidogenic microbial consortia Abs: In time course experiments, bacterial community compositions were compared between a sulfidogenic and two nonsulfidogenic Cr(VI)-reducing consortia enriched from metal-contaminated sediments. The consortia were subjected to 0 and 0.85 mM or 1.35 mM Cr(VI), and Cr(VI) reduction, growth, and denaturing gradient gel electrophoresis profiles of PCR products of small-subunit (16S) ribosomal genes were compared. Results showed that although Cr(VI) was completely reduced by the three consortia, Cr(VI) inhibited cell growth, with sulfate-reducing bacteria being particularly sensitive to Cr(VI) toxicity relative to other bacteria in the consortia."
1232057,Ganeshjeevan et al. 2003,Determination of hexavalent chromium by on-line dialysis ion chromatography in a matrix of strong colourants and trivalent chromium,"Hexavalent chromium detection in the presence of a high load of colourants without any false positive and in-procedure oxidation of Cr(III) is an important area of study. Colourants are a class of interfering substances in many spectroscopic analyses and chromatographic separations and detection. A purification method using an on-line dialysis technique for ion chromatography (IC) has been developed to remove water-soluble anionic dyes and particulate colourants and other substances to facilitate Cr(VI) quantification and the method is discussed. The dialysis was optimized with Cr(VI) standard solutions for quantification. The efficacy of the procedure for the removal of anionic dyes and detection of Cr(VI) was checked with a Cr(VI) spiked synthetic preparation containing a water-soluble dye and trivalent chromium. Soluble Cr(VI) extracted with organic dyes from environmental samples was analyzed. The method has a detection limit of 5 microg/l, recovery rate of 100% and analysis time less than 20 min.","Determination of hexavalent chromium by on-line dialysis ion chromatography in a matrix of strong colourants and trivalent chromium Abs: Hexavalent chromium detection in the presence of a high load of colourants without any false positive and in-procedure oxidation of Cr(III) is an important area of study. Colourants are a class of interfering substances in many spectroscopic analyses and chromatographic separations and detection. A purification method using an on-line dialysis technique for ion chromatography (IC) has been developed to remove water-soluble anionic dyes and particulate colourants and other substances to facilitate Cr(VI) quantification and the method is discussed. The dialysis was optimized with Cr(VI) standard solutions for quantification. The efficacy of the procedure for the removal of anionic dyes and detection of Cr(VI) was checked with a Cr(VI) spiked synthetic preparation containing a water-soluble dye and trivalent chromium. Soluble Cr(VI) extracted with organic dyes from environmental samples was analyzed. The method has a detection limit of 5 microg/l, recovery rate of 100% and analysis time less than 20 min."
1232055,Alguacil and  Alonso 2003,Chromium(VI) removal through facilitated transport using CYANEX 923 as carrier and reducing stripping with hydrazine sulfate,"The transport of chromium(VI) through a flat-sheet supported liquid membrane (FSSLM) containing CYANEX 923 (mixture of phosphine oxides) as a carrier has been studied. The permeation of the metal is investigated as a function of various experimental variables: hydrodynamic conditions, concentration of chromium(VI) and HCI in the feed phase, CYANEX 923 concentration and diluent in the membrane, and strippant concentration in the receiving phase. By using hydrazine sulfate in the receiving phase, chromium(VI) is immediately reduced to the less toxic chromium(III). The aqueous mass transfer coefficient and the thickness of the aqueous boundary layer were calculated from the experimental results. The selectivity of CYANEX 923-based FSSLM toward different metal ions and the behavior of the system against other carriers is presented.","Chromium(VI) removal through facilitated transport using CYANEX 923 as carrier and reducing stripping with hydrazine sulfate Abs: The transport of chromium(VI) through a flat-sheet supported liquid membrane (FSSLM) containing CYANEX 923 (mixture of phosphine oxides) as a carrier has been studied. The permeation of the metal is investigated as a function of various experimental variables: hydrodynamic conditions, concentration of chromium(VI) and HCI in the feed phase, CYANEX 923 concentration and diluent in the membrane, and strippant concentration in the receiving phase. By using hydrazine sulfate in the receiving phase, chromium(VI) is immediately reduced to the less toxic chromium(III). The aqueous mass transfer coefficient and the thickness of the aqueous boundary layer were calculated from the experimental results. The selectivity of CYANEX 923-based FSSLM toward different metal ions and the behavior of the system against other carriers is presented."
1232053,Camargo et al. 2003,In vitro reduction of hexavalent chromium by a cell-free extract of Bacillus sp. ES 29 stimulated by Cu2+,"Chromium-resistant bacteria (CRB) isolated from soils can be used to reduce toxic Cr(VI) from contaminated environments. This study assessed in vitro reduction of hexavalent Cr using a cell-free extract (CFE) of CRB isolated from soil contaminated with dichromate. One isolate, ES 29, that substantially reduced Cr(VI) was identified as a Bacillus species by 16S rRNA gene-sequence homology. The isolate reduced Cr(VI) under aerobic conditions, using NADH as an electron donor and produced a soluble Cr(VI)-reducing enzyme stimulated by copper (Cu2+). The CFE of the bacterial isolate reduced 50% of Cr(VI) in 6 h. The Cr(VI)-reduction activity of the CFE had a Km of 7.09 microM and a Vmax of 0.171 micromol min(-1) mg(-1) protein. Mercury inhibited the enzyme, but not competitively, with a Vmax of 0.143 micromol min(-1) mg(-1) protein, a Km of 7.07 microM and a Ki of 1.58 microM. This study characterizes the enzymatic reduction of Cr(VI) by Bacillus sp. ES 29 which can be used for the bioremediation of chromate.","In vitro reduction of hexavalent chromium by a cell-free extract of Bacillus sp. ES 29 stimulated by Cu2+ Abs: Chromium-resistant bacteria (CRB) isolated from soils can be used to reduce toxic Cr(VI) from contaminated environments. This study assessed in vitro reduction of hexavalent Cr using a cell-free extract (CFE) of CRB isolated from soil contaminated with dichromate. One isolate, ES 29, that substantially reduced Cr(VI) was identified as a Bacillus species by 16S rRNA gene-sequence homology. The isolate reduced Cr(VI) under aerobic conditions, using NADH as an electron donor and produced a soluble Cr(VI)-reducing enzyme stimulated by copper (Cu2+). The CFE of the bacterial isolate reduced 50% of Cr(VI) in 6 h. The Cr(VI)-reduction activity of the CFE had a Km of 7.09 microM and a Vmax of 0.171 micromol min(-1) mg(-1) protein. Mercury inhibited the enzyme, but not competitively, with a Vmax of 0.143 micromol min(-1) mg(-1) protein, a Km of 7.07 microM and a Ki of 1.58 microM. This study characterizes the enzymatic reduction of Cr(VI) by Bacillus sp. ES 29 which can be used for the bioremediation of chromate."
1232051,Tzou et al. 2003,Effect of N-hydroxyethyl-ethylenediamine-triacetic acid (HEDTA) on Cr(VI) reduction by Fe(II),"The complexation of Fe(II) with organic ligand results in the decrease of redox potential, and enhances the reduction ability of Fe(II). An important example is the use of Fe(II)-organic complexes to accelerate Cr(VI) reduction. Dissolved O(2) and light can potentially affect Cr(VI) reduction; however, these two factors have not been adequately evaluated. A batch technique was used to investigate the Cr(VI) reduction as influenced by the light and dissolved O(2) using N-hydroxyethyl-ethylenediamine-triacetic acid (HEDTA) and Fe(II) solutions. The oxidation of Fe(II) by dissolved O(2) was rapid in the presence of HEDTA at low pH; nonetheless, the oxidation proceeded slowly when HEDTA was absent. Although Cr(VI) could be reduced by free Fe(II) at low pH, the reaction was considerably slower than that of systems involving HEDTA. The enhancement of Cr(VI) reduction by Fe(II) in the presence of high concentrations of HEDTA was achieved as a result of two processes. First, HEDTA acted as a ligand for expediting electron transfer between Fe(II) and Cr(VI). Secondly, HEDTA served as a reductant for Cr(VI) under illumination.","Effect of N-hydroxyethyl-ethylenediamine-triacetic acid (HEDTA) on Cr(VI) reduction by Fe(II) Abs: The complexation of Fe(II) with organic ligand results in the decrease of redox potential, and enhances the reduction ability of Fe(II). An important example is the use of Fe(II)-organic complexes to accelerate Cr(VI) reduction. Dissolved O(2) and light can potentially affect Cr(VI) reduction; however, these two factors have not been adequately evaluated. A batch technique was used to investigate the Cr(VI) reduction as influenced by the light and dissolved O(2) using N-hydroxyethyl-ethylenediamine-triacetic acid (HEDTA) and Fe(II) solutions. The oxidation of Fe(II) by dissolved O(2) was rapid in the presence of HEDTA at low pH; nonetheless, the oxidation proceeded slowly when HEDTA was absent. Although Cr(VI) could be reduced by free Fe(II) at low pH, the reaction was considerably slower than that of systems involving HEDTA. The enhancement of Cr(VI) reduction by Fe(II) in the presence of high concentrations of HEDTA was achieved as a result of two processes. First, HEDTA acted as a ligand for expediting electron transfer between Fe(II) and Cr(VI). Secondly, HEDTA served as a reductant for Cr(VI) under illumination."
1232048,Tokunaga et al. 2003,Distribution of chromium contamination and microbial activity in soil aggregates,"Biogeochemical transformations of redox-sensitive chemicals in soils can be strongly transport-controlled and localized. This was tested through experiments on chromium diffusion and reduction in soil aggregates that were exposed to chromate solutions. Reduction of soluble Cr(VI) to insoluble Cr(II) occurred only within the surface layer of aggregates with higher available organic carbon and higher microbial respiration. Sharply terminated Cr diffusion fronts develop when the reduction rate increases rapidly with depth. The final state of such aggregates consists of a Cr-contaminated exterior, and an uncontaminated core, each having different microbial community compositions and activity. Microbial activity was significantly higher in the more reducing soils, while total microbial biomass was similar in all of the soils. The small fraction of Cr(VI) remaining unreduced resides along external surfaces of aggregates, leaving it potentially available to future transport down the soil profile. Using the Thiele modulus, Cr(VI) reduction in soil aggregates is shown to be diffusion rate- and reaction rate-limited in anaerobic and aerobic aggregates, respectively. Thus, spatially resolved chemical and microbiological measurements are necessary within anaerobic soil aggregates to characterize and predict the fate of Cr contamination. Typical methods of soil sampling and analyses that average over redox gradients within aggregates can erase important biogeochemical spatial relations necessary for understanding these environments.","Distribution of chromium contamination and microbial activity in soil aggregates Abs: Biogeochemical transformations of redox-sensitive chemicals in soils can be strongly transport-controlled and localized. This was tested through experiments on chromium diffusion and reduction in soil aggregates that were exposed to chromate solutions. Reduction of soluble Cr(VI) to insoluble Cr(II) occurred only within the surface layer of aggregates with higher available organic carbon and higher microbial respiration. Sharply terminated Cr diffusion fronts develop when the reduction rate increases rapidly with depth. The final state of such aggregates consists of a Cr-contaminated exterior, and an uncontaminated core, each having different microbial community compositions and activity. Microbial activity was significantly higher in the more reducing soils, while total microbial biomass was similar in all of the soils. The small fraction of Cr(VI) remaining unreduced resides along external surfaces of aggregates, leaving it potentially available to future transport down the soil profile. Using the Thiele modulus, Cr(VI) reduction in soil aggregates is shown to be diffusion rate- and reaction rate-limited in anaerobic and aerobic aggregates, respectively. Thus, spatially resolved chemical and microbiological measurements are necessary within anaerobic soil aggregates to characterize and predict the fate of Cr contamination. Typical methods of soil sampling and analyses that average over redox gradients within aggregates can erase important biogeochemical spatial relations necessary for understanding these environments."
1232047,Rocchetta et al. 2003,Effects of hexavalent chromium in two strains of Euglena gracilis,,Effects of hexavalent chromium in two strains of Euglena gracilis Abs: 
1232046,Guha et al. 2003,Microbiological reduction of chromium(VI) in presence of pyrolusite-coated sand by Shewanella alga Simidu ATCC 55627 in laboratory column experiments,"Hexavalent chromium (Cr(VI)) was reduced to non-toxic trivalent chromium (Cr(III)) by a dissimilatory metal reducing bacteria, Shewanella alga Simidu (BrY-MT) ATCC 55627. A series of dynamic column experiments were conducted to provide an understanding of Cr(VI) reduction by the facultative anaerobe BrY-MT in the presence of pyrolusite (beta-MnO(2)) coated sand and uncoated-quartz sand. All dynamic column experiments were conducted under growth conditions using Cr(VI) as the terminal electron acceptor and lactate as the electron donor and energy source. Reduction of Cr(VI) was rapid (within 8 h) in columns packed with uncoated quartz sand and BrY-MT, whereas Cr(VI) reduction by BrY-MT was delayed (57 h) in the presence of beta-MnO(2)-coated sand. The role of beta-MnO(2) in this study was to provide oxidation of trivalent chromium (Cr(III)). BrY-MT attachment was higher on beta-MnO(2)-coated sand than on uncoated quartz sand at 10, 60, and 85.5 h. Results have shown that this particular strain of Shewanella did not appreciably reduce Mn(IV) to Mn(II) species nor biosorbed Cr and Mn during its metabolic activities.","Microbiological reduction of chromium(VI) in presence of pyrolusite-coated sand by Shewanella alga Simidu ATCC 55627 in laboratory column experiments Abs: Hexavalent chromium (Cr(VI)) was reduced to non-toxic trivalent chromium (Cr(III)) by a dissimilatory metal reducing bacteria, Shewanella alga Simidu (BrY-MT) ATCC 55627. A series of dynamic column experiments were conducted to provide an understanding of Cr(VI) reduction by the facultative anaerobe BrY-MT in the presence of pyrolusite (beta-MnO(2)) coated sand and uncoated-quartz sand. All dynamic column experiments were conducted under growth conditions using Cr(VI) as the terminal electron acceptor and lactate as the electron donor and energy source. Reduction of Cr(VI) was rapid (within 8 h) in columns packed with uncoated quartz sand and BrY-MT, whereas Cr(VI) reduction by BrY-MT was delayed (57 h) in the presence of beta-MnO(2)-coated sand. The role of beta-MnO(2) in this study was to provide oxidation of trivalent chromium (Cr(III)). BrY-MT attachment was higher on beta-MnO(2)-coated sand than on uncoated quartz sand at 10, 60, and 85.5 h. Results have shown that this particular strain of Shewanella did not appreciably reduce Mn(IV) to Mn(II) species nor biosorbed Cr and Mn during its metabolic activities."
1232045,Bai and  Abraham 2003,Studies on chromium(VI) adsorption-desorption using immobilized fungal biomass,"The aim of this study was to investigate the Cr(VI) biosorption potential of immobilized Rhizopus nigricans and to screen a variety of non-toxic desorbing agents, in order to find out possible application in multiple sorption-desorption cycles. The biomass was immobilized by various mechanisms and evaluated for removal of Cr(VI) from aqueous solution, mechanical stability to desorbents, and reuse in successive cycles. The finely powdered biomass, entrapped in five different polymeric matrices viz. calcium alginate, polyvinyl alcohol (PVA), polyacrylamide, polyisoprene, and polysulfone was compared for biosorption efficiency and stability to desorbents. Physical immobilization to polyurethane foam and coir fiber was less efficient than polymer entrapment methods. Of the different combinations (%, w/v) of biomass dose compared for each matrix, 8% (calcium alginate), 6% (polyacrylamide and PVA), 12% (polyisoprene), and 10% (polysulfone) were found to be the optimum. The Cr sorption capacity (mg Cr/g sorbent) of all immobilized biomass was lesser than the native, powdered biomass. The Cr sorption capacity decreased in the order of free biomass (119.2) &gt; polysulfone entrapped (101.5) &gt; polyisoprene immobilized (98.76) &gt; PVA immobilized (96.69) &gt; calcium alginate entrapped (84.29) &gt; polyacrylamide (45.56), at 500 mg/l concentration of Cr(VI). The degree of mechanical stability and chemical resistance of the immobilized systems were in the order of polysulfone &gt; polyisoprene &gt; PVA &gt; polyacrylamide &gt; calcium alginate. The bound Cr(VI) could be eluted successfully using 0.01 N NaOH, NaHCO3, and Na2CO3. The adsorption data for the native and the immobilized biomass was evaluated by the Freundlich isotherm model. The successive sorption-desorption studies employing polysulfone entrapped biomass indicated that the biomass beads could be regenerated and reused in more than 25 cycles and the regeneration efficiency was 75-78%.","Studies on chromium(VI) adsorption-desorption using immobilized fungal biomass Abs: The aim of this study was to investigate the Cr(VI) biosorption potential of immobilized Rhizopus nigricans and to screen a variety of non-toxic desorbing agents, in order to find out possible application in multiple sorption-desorption cycles. The biomass was immobilized by various mechanisms and evaluated for removal of Cr(VI) from aqueous solution, mechanical stability to desorbents, and reuse in successive cycles. The finely powdered biomass, entrapped in five different polymeric matrices viz. calcium alginate, polyvinyl alcohol (PVA), polyacrylamide, polyisoprene, and polysulfone was compared for biosorption efficiency and stability to desorbents. Physical immobilization to polyurethane foam and coir fiber was less efficient than polymer entrapment methods. Of the different combinations (%, w/v) of biomass dose compared for each matrix, 8% (calcium alginate), 6% (polyacrylamide and PVA), 12% (polyisoprene), and 10% (polysulfone) were found to be the optimum. The Cr sorption capacity (mg Cr/g sorbent) of all immobilized biomass was lesser than the native, powdered biomass. The Cr sorption capacity decreased in the order of free biomass (119.2) &gt; polysulfone entrapped (101.5) &gt; polyisoprene immobilized (98.76) &gt; PVA immobilized (96.69) &gt; calcium alginate entrapped (84.29) &gt; polyacrylamide (45.56), at 500 mg/l concentration of Cr(VI). The degree of mechanical stability and chemical resistance of the immobilized systems were in the order of polysulfone &gt; polyisoprene &gt; PVA &gt; polyacrylamide &gt; calcium alginate. The bound Cr(VI) could be eluted successfully using 0.01 N NaOH, NaHCO3, and Na2CO3. The adsorption data for the native and the immobilized biomass was evaluated by the Freundlich isotherm model. The successive sorption-desorption studies employing polysulfone entrapped biomass indicated that the biomass beads could be regenerated and reused in more than 25 cycles and the regeneration efficiency was 75-78%."
1232044,Deng et al. 2003,Effects of clay minerals on Cr(VI) reduction by organic compounds,"The objective of this study is to examine the effect of clay minerals (illite, montmorillonite, and kaolinite) on chromate (Cr(VI)) reduction by several low molecular weight organic compounds. Batch experiments at pH ranging from 3.0 to 6.0 and 25 degrees C showed that 2:1 layered clays illite and smectite catalyzed Cr(VI) reduction by oxalate. The catalytic effect increased as pH was decreased. The 1:1 clay kaolinite had no catalytic effect under comparable conditions. Direct Cr(VI) reduction by reactive moieties associated with illite and montmorillonite was observed, but at a much slower rate than the catalytic pathway. Cr(VI) reduction by glyoxylic acid, glycolic acid, lactic acid, and mandelic acid was accelerated by illite, although aqueous phase reduction might occur in parallel. These results suggest that Cr(VI) reduction rates in subsurface environments rich in organic compounds may be elevated through catalysis of surface-bound metals and/or soluble species from the clay minerals, and as a result, higher than those expected from aqueous phase reaction alone. Such rate enhancement for Cr(VI) reduction needs to be accounted for when developing new remedial techniques for chromium site remediation or assessing its natural attenuation.","Effects of clay minerals on Cr(VI) reduction by organic compounds Abs: The objective of this study is to examine the effect of clay minerals (illite, montmorillonite, and kaolinite) on chromate (Cr(VI)) reduction by several low molecular weight organic compounds. Batch experiments at pH ranging from 3.0 to 6.0 and 25 degrees C showed that 2:1 layered clays illite and smectite catalyzed Cr(VI) reduction by oxalate. The catalytic effect increased as pH was decreased. The 1:1 clay kaolinite had no catalytic effect under comparable conditions. Direct Cr(VI) reduction by reactive moieties associated with illite and montmorillonite was observed, but at a much slower rate than the catalytic pathway. Cr(VI) reduction by glyoxylic acid, glycolic acid, lactic acid, and mandelic acid was accelerated by illite, although aqueous phase reduction might occur in parallel. These results suggest that Cr(VI) reduction rates in subsurface environments rich in organic compounds may be elevated through catalysis of surface-bound metals and/or soluble species from the clay minerals, and as a result, higher than those expected from aqueous phase reaction alone. Such rate enhancement for Cr(VI) reduction needs to be accounted for when developing new remedial techniques for chromium site remediation or assessing its natural attenuation."
1232043,Proctor et al. 2003,"Workplace airborne hexavalent chromium concentrations for the Painesville, Ohio, chromate production plant (1943-1971)","Hexavalent chromium [Cr(VI)] is recognized as an inhalation carcinogen, based primarily on the increased incidence of lung cancer among occupationally exposed workers. To assess the carcinogenic potency of Cr(VI), both the U.S. Environmental Protection Agency and the Occupational Safety and Health Administration have relied on data from a 1930s cohort of workers from the Painesville, Ohio, chromate production plant. However, the exposure information for this cohort has several shortcomings. In an effort to provide better exposure information, we present here recently identified historical exposure data for the Painesville workers. More than 800 measurements of airborne Cr(VI) from 23 newly identified surveys conducted from 1943 to 1971 are presented. The results indicate that the highest Cr(VI) concentrations recorded at the plant occurred in shipping (e.g., bagging of dichromate), lime and ash, and filtering operations, with maximum yearly average Cr(VI) concentrations of 8.9, 2.7, and 2.3 mg/m(3), respectively. The locker rooms, laboratory, maintenance shop, and outdoor raw liquor storage areas had the lowest average Cr(VI) air concentrations over time, with yearly average concentrations that rarely exceeded the historical and current Threshold Limit Value TLV(R) of 0.05 mgCr(VI)/m(3) (0.1 mgCrO(3)/m(3)). Concentrations generally decreased in the plant over time. The average airborne concentration of Cr(VI) in the indoor operating areas of the plant in the 1940s was 0.72 mg/m(3), that from 1957 through 1964 was 0.27 mg/m(3), and that from 1965 through 1972 was 0.039 mg/m(3). Although in some ways limited, these data are of sufficient quality to allow for exposure reconstruction for workers employed at this plant from 1940 to 1972, and to provide the basis for an improved cancer risk assessment.","Workplace airborne hexavalent chromium concentrations for the Painesville, Ohio, chromate production plant (1943-1971) Abs: Hexavalent chromium [Cr(VI)] is recognized as an inhalation carcinogen, based primarily on the increased incidence of lung cancer among occupationally exposed workers. To assess the carcinogenic potency of Cr(VI), both the U.S. Environmental Protection Agency and the Occupational Safety and Health Administration have relied on data from a 1930s cohort of workers from the Painesville, Ohio, chromate production plant. However, the exposure information for this cohort has several shortcomings. In an effort to provide better exposure information, we present here recently identified historical exposure data for the Painesville workers. More than 800 measurements of airborne Cr(VI) from 23 newly identified surveys conducted from 1943 to 1971 are presented. The results indicate that the highest Cr(VI) concentrations recorded at the plant occurred in shipping (e.g., bagging of dichromate), lime and ash, and filtering operations, with maximum yearly average Cr(VI) concentrations of 8.9, 2.7, and 2.3 mg/m(3), respectively. The locker rooms, laboratory, maintenance shop, and outdoor raw liquor storage areas had the lowest average Cr(VI) air concentrations over time, with yearly average concentrations that rarely exceeded the historical and current Threshold Limit Value TLV(R) of 0.05 mgCr(VI)/m(3) (0.1 mgCrO(3)/m(3)). Concentrations generally decreased in the plant over time. The average airborne concentration of Cr(VI) in the indoor operating areas of the plant in the 1940s was 0.72 mg/m(3), that from 1957 through 1964 was 0.27 mg/m(3), and that from 1965 through 1972 was 0.039 mg/m(3). Although in some ways limited, these data are of sufficient quality to allow for exposure reconstruction for workers employed at this plant from 1940 to 1972, and to provide the basis for an improved cancer risk assessment."
1232042,Kinoshita et al. 2003,Evidence of hexavalent chromium ingestion,"We describe the application of histochemical demonstration of chromium in a case of fatal ingestion of potassium dichromate in a suicide attempt. Using 2-(8-quinolylazo)-4,5-di-p-tolylimidazole (QTI), we could demonstrate chromium in the erythrocyte of the victim, in situ. This finding provides a means of proving the hexavalent chromium ingestion.","Evidence of hexavalent chromium ingestion Abs: We describe the application of histochemical demonstration of chromium in a case of fatal ingestion of potassium dichromate in a suicide attempt. Using 2-(8-quinolylazo)-4,5-di-p-tolylimidazole (QTI), we could demonstrate chromium in the erythrocyte of the victim, in situ. This finding provides a means of proving the hexavalent chromium ingestion."
1232040,Gambelunghe et al. 2003,Primary DNA damage in chrome-plating workers,"In order to evaluate the primary DNA damage due to occupational exposure to chromium (VI), DNA strand-breaks and apoptosis in peripheral lymphocytes were measured in a group of 19 chrome-plating workers. DNA strand-breaks was assessed by alkaline (pH&gt;13) single-cell microgel electrophoresis ('comet') assay, while apoptosis was measured by flow-cytometry after propidium iodide staining of the cells. Concentrations of chromium in urine, erythrocytes and lymphocytes were investigated as biological indicators of exposure. A group of 18 hospital workers (control group I) and another 20 university personnel (control group II) without exposure to chromium were also studied as controls. The results of the study show that chrome-plating workers have higher levels of chromium in urine, erythrocytes and lymphocytes than unexposed workers. Comet tail moment values, assumed as index of DNA damage, are increased in chromium-exposed workers and results are significantly correlated to chromium lymphocyte concentrations. No difference emerged in the percentage of apoptotic nuclei in exposed and unexposed workers. The study confirms that measurements of chromium in erythrocytes and lymphocytes may provide useful information about recent and past exposure to hexavalent chromium at the workplace. The increase in DNA strand-breaks measured by comet assay suggests this test is valid for the biological monitoring of workers exposed to genotoxic compounds such as chromium (VI).","Primary DNA damage in chrome-plating workers Abs: In order to evaluate the primary DNA damage due to occupational exposure to chromium (VI), DNA strand-breaks and apoptosis in peripheral lymphocytes were measured in a group of 19 chrome-plating workers. DNA strand-breaks was assessed by alkaline (pH&gt;13) single-cell microgel electrophoresis ('comet') assay, while apoptosis was measured by flow-cytometry after propidium iodide staining of the cells. Concentrations of chromium in urine, erythrocytes and lymphocytes were investigated as biological indicators of exposure. A group of 18 hospital workers (control group I) and another 20 university personnel (control group II) without exposure to chromium were also studied as controls. The results of the study show that chrome-plating workers have higher levels of chromium in urine, erythrocytes and lymphocytes than unexposed workers. Comet tail moment values, assumed as index of DNA damage, are increased in chromium-exposed workers and results are significantly correlated to chromium lymphocyte concentrations. No difference emerged in the percentage of apoptotic nuclei in exposed and unexposed workers. The study confirms that measurements of chromium in erythrocytes and lymphocytes may provide useful information about recent and past exposure to hexavalent chromium at the workplace. The increase in DNA strand-breaks measured by comet assay suggests this test is valid for the biological monitoring of workers exposed to genotoxic compounds such as chromium (VI)."
1232039,Aldrich et al. 2003,Uptake and reduction of Cr(VI) to Cr(III) by mesquite (Prosopis spp.): chromate-plant interaction in hydroponics and solid media studied using XAS,"Chromium (Cr) is a well-established carcinogen that is a contaminant at half of the EPA Superfund sites in the United States. Two separate studies were performed to investigate the possibility that mesquite (Prosopis spp.), which is an indigenous desert plant species, can remove Cr from the environment via active transport systems to the aerial portions of the plant. The first study was performed by growing mesquite on solid media (agar) at Cr(VI) concentrations of 75 and 125 ppm. The accumulation found in the leaves under the present conditions indicated that mesquite could be classified as a hyperaccumulator of chromium. The second study was conducted to investigate the differences between the type of Cr ligand involved in Cr uptake with agar and hydroponic cultures. We used X-ray absorption spectroscopy (XAS) to determine the mechanisms involved in the uptake and binding of Cr(VI) in live mesquite tissue. The XAS results for this study showed that some of the supplied Cr(VI) was uptaken by the mesquite roots; however, the data analyses of the plant tissues demonstrated that it was fully reduced to Cr(III) in the leaf tissues. Experiments are currently being performed to evaluate the behavior of the Mesquite plant using lower Cr concentrations.","Uptake and reduction of Cr(VI) to Cr(III) by mesquite (Prosopis spp.): chromate-plant interaction in hydroponics and solid media studied using XAS Abs: Chromium (Cr) is a well-established carcinogen that is a contaminant at half of the EPA Superfund sites in the United States. Two separate studies were performed to investigate the possibility that mesquite (Prosopis spp.), which is an indigenous desert plant species, can remove Cr from the environment via active transport systems to the aerial portions of the plant. The first study was performed by growing mesquite on solid media (agar) at Cr(VI) concentrations of 75 and 125 ppm. The accumulation found in the leaves under the present conditions indicated that mesquite could be classified as a hyperaccumulator of chromium. The second study was conducted to investigate the differences between the type of Cr ligand involved in Cr uptake with agar and hydroponic cultures. We used X-ray absorption spectroscopy (XAS) to determine the mechanisms involved in the uptake and binding of Cr(VI) in live mesquite tissue. The XAS results for this study showed that some of the supplied Cr(VI) was uptaken by the mesquite roots; however, the data analyses of the plant tissues demonstrated that it was fully reduced to Cr(III) in the leaf tissues. Experiments are currently being performed to evaluate the behavior of the Mesquite plant using lower Cr concentrations."
1232038,Stasinakis et al. 2003,Chromium species behaviour in the activated sludge process,"The purpose of this research was to compare trivalent chromium (Cr(III)) and hexavalent chromium (Cr(VI)) removal by activated sludge and to investigate whether Cr(VI) reduction and/or Cr(III) oxidation occurs in a wastewater treatment system. Chromium removal by sludge harvested from sequencing batch reactors, determined by a series of batch experiments, generally followed a Freundlich isotherm model. Almost 90% of Cr(III) was adsorbed on the suspended solids while the rest was precipitated at pH 7.0. On the contrary, removal of Cr(VI) was minor and did not exceed 15% in all experiments under the same conditions. Increase of sludge age reduces Cr(III) removal, possibly because of Cr(III) sorption on slime polymers. Moreover, the decrease of suspended solids concentration and the acclimatization of biomass to Cr(VI) reduced the removal efficiency of Cr(III). Batch experiments showed that Cr(III) cannot be oxidized to Cr(VI) by activated sludge. On the contrary, Cr(VI) reduction is possible and is affected mainly by the initial concentration of organic substrate, which acts as electron donor for Cr(VI) reduction. Initial organic substrate concentration equal to or higher than 1000 mgl(-1) chemical oxygen demand permitted the nearly complete reduction of 5 mgl(-1) Cr(VI) in a 24-h batch experiment. Moreover, higher Cr(VI) reduction rates were obtained with higher Cr(VI) initial concentrations, expressed in mg Cr(VI) g(-1) VSS, while decrease of suspended solids concentration enhanced the specific Cr(VI) reduction rate.","Chromium species behaviour in the activated sludge process Abs: The purpose of this research was to compare trivalent chromium (Cr(III)) and hexavalent chromium (Cr(VI)) removal by activated sludge and to investigate whether Cr(VI) reduction and/or Cr(III) oxidation occurs in a wastewater treatment system. Chromium removal by sludge harvested from sequencing batch reactors, determined by a series of batch experiments, generally followed a Freundlich isotherm model. Almost 90% of Cr(III) was adsorbed on the suspended solids while the rest was precipitated at pH 7.0. On the contrary, removal of Cr(VI) was minor and did not exceed 15% in all experiments under the same conditions. Increase of sludge age reduces Cr(III) removal, possibly because of Cr(III) sorption on slime polymers. Moreover, the decrease of suspended solids concentration and the acclimatization of biomass to Cr(VI) reduced the removal efficiency of Cr(III). Batch experiments showed that Cr(III) cannot be oxidized to Cr(VI) by activated sludge. On the contrary, Cr(VI) reduction is possible and is affected mainly by the initial concentration of organic substrate, which acts as electron donor for Cr(VI) reduction. Initial organic substrate concentration equal to or higher than 1000 mgl(-1) chemical oxygen demand permitted the nearly complete reduction of 5 mgl(-1) Cr(VI) in a 24-h batch experiment. Moreover, higher Cr(VI) reduction rates were obtained with higher Cr(VI) initial concentrations, expressed in mg Cr(VI) g(-1) VSS, while decrease of suspended solids concentration enhanced the specific Cr(VI) reduction rate."
1232037,Megharaj et al. 2003,Toxicity of hexavalent chromium and its reduction by bacteria isolated from soil contaminated with tannery waste,"An Arthrobacter sp. and a Bacillus sp., isolated from a long-term tannery waste contaminated soil, were examined for their tolerance to hexavalent chromium [Cr(VI)] and their ability to reduce Cr(VI) to Cr(III), a detoxification process in cell suspensions and cell extracts. Both bacteria tolerated Cr(VI) at 100 mg/ml on a minimal salts agar medium supplemented with 0.5% glucose, but only Arthrobacter could grow in liquid medium at this concentration. Arthrobacter sp. could reduce Cr(VI) up to 50 microg/ml, while Bacillus sp. was not able to reduce Cr(VI) beyond 20 microg/ml. Arthrobacter sp. was distinctly superior to the Bacillus sp. in terms of their Cr(VI)-reducing ability and resistance to Cr(VI). Assays with permeabilized (treated with toluene or Triton X 100) cells and crude extracts demonstrated that the Cr(VI) reduction was mainly associated with the soluble protein fraction of the cell. Arthrobacter sp. has a great potential for bioremediation of Cr(VI)-containing waste.","Toxicity of hexavalent chromium and its reduction by bacteria isolated from soil contaminated with tannery waste Abs: An Arthrobacter sp. and a Bacillus sp., isolated from a long-term tannery waste contaminated soil, were examined for their tolerance to hexavalent chromium [Cr(VI)] and their ability to reduce Cr(VI) to Cr(III), a detoxification process in cell suspensions and cell extracts. Both bacteria tolerated Cr(VI) at 100 mg/ml on a minimal salts agar medium supplemented with 0.5% glucose, but only Arthrobacter could grow in liquid medium at this concentration. Arthrobacter sp. could reduce Cr(VI) up to 50 microg/ml, while Bacillus sp. was not able to reduce Cr(VI) beyond 20 microg/ml. Arthrobacter sp. was distinctly superior to the Bacillus sp. in terms of their Cr(VI)-reducing ability and resistance to Cr(VI). Assays with permeabilized (treated with toluene or Triton X 100) cells and crude extracts demonstrated that the Cr(VI) reduction was mainly associated with the soluble protein fraction of the cell. Arthrobacter sp. has a great potential for bioremediation of Cr(VI)-containing waste."
1232033,Yu et al. 2003,Adsorption of chromium from aqueous solutions by maple sawdust,"This paper presents the data for the effect of adsorbent dose, initial sorbate concentration, contact time, and pH on the adsorption of chromium(VI) on maple sawdust. Batch adsorption studies have been carried out. An empirical relationship has been obtained to predict the percentage chromium(VI) removal at any time for known values of sorbent and initial sorbate concentration. Under observed test conditions, the equilibrium adsorption data fits the linear Langmuir and Freundlich isotherms. The experimental result inferred that chelation ion exchange is one of the major adsorption mechanisms for binding metal ions to the maple sawdust.","Adsorption of chromium from aqueous solutions by maple sawdust Abs: This paper presents the data for the effect of adsorbent dose, initial sorbate concentration, contact time, and pH on the adsorption of chromium(VI) on maple sawdust. Batch adsorption studies have been carried out. An empirical relationship has been obtained to predict the percentage chromium(VI) removal at any time for known values of sorbent and initial sorbate concentration. Under observed test conditions, the equilibrium adsorption data fits the linear Langmuir and Freundlich isotherms. The experimental result inferred that chelation ion exchange is one of the major adsorption mechanisms for binding metal ions to the maple sawdust."
1232031,Bond and  Fendorf 2003,Kinetics and structural constraints of chromate reduction by green rusts,"Green rusts, ferrous-ferric iron oxides, occur in many anaerobic soils and sediments and are highly reactive, making them important phases impacting the fate and transport of environmental contaminants. Despite their potential importance in environmental settings, reactions involving green rusts remain rather poorly described. Chromate is a widespread contaminant having deleterious impacts on plant and animal health; its fate may in part be controlled by green rust. Here we examine chromate reduction by a series of green rust phases and resolve the reaction kinetics at pH 7. The overall kinetics of the reactions are well described by the expression d[Cr(VI)]/dt = -k[Cr(VI)][GR], and this model was successfully used to predict rates of reaction at varying chromium concentrations. The rates of reduction are controlled by the concentration of ferrous iron, surface area, and chemical structure of the green rust including layer spacing. On a mass basis, green rust (GR) chloride is the most rapid reductant of Cr(VI) followed by GRCO3 and GRSO4, with pseudo-first-order rate coefficients (k(obs)) (with respect to Cr(VI) concentration) ranging from 1.22 x 10(-3) to 3.7 x 10(-2) s(-1). Chromium(III)-substituted magnetite and lepidocrocite were identified as the major oxidation products. The nature of the oxidation products appears to be independent of the anionic class of green rust, but their respective concentrations display a dependence on the initial GR. The mole fraction of Fe(III) in the Cr(x),Fe(1-x)(OH)3 x nH2O reaction product ranged from 17% to 68%, leading to a highly stabilized (low solubility) phase.","Kinetics and structural constraints of chromate reduction by green rusts Abs: Green rusts, ferrous-ferric iron oxides, occur in many anaerobic soils and sediments and are highly reactive, making them important phases impacting the fate and transport of environmental contaminants. Despite their potential importance in environmental settings, reactions involving green rusts remain rather poorly described. Chromate is a widespread contaminant having deleterious impacts on plant and animal health; its fate may in part be controlled by green rust. Here we examine chromate reduction by a series of green rust phases and resolve the reaction kinetics at pH 7. The overall kinetics of the reactions are well described by the expression d[Cr(VI)]/dt = -k[Cr(VI)][GR], and this model was successfully used to predict rates of reaction at varying chromium concentrations. The rates of reduction are controlled by the concentration of ferrous iron, surface area, and chemical structure of the green rust including layer spacing. On a mass basis, green rust (GR) chloride is the most rapid reductant of Cr(VI) followed by GRCO3 and GRSO4, with pseudo-first-order rate coefficients (k(obs)) (with respect to Cr(VI) concentration) ranging from 1.22 x 10(-3) to 3.7 x 10(-2) s(-1). Chromium(III)-substituted magnetite and lepidocrocite were identified as the major oxidation products. The nature of the oxidation products appears to be independent of the anionic class of green rust, but their respective concentrations display a dependence on the initial GR. The mole fraction of Fe(III) in the Cr(x),Fe(1-x)(OH)3 x nH2O reaction product ranged from 17% to 68%, leading to a highly stabilized (low solubility) phase."
1232030,Blankert et al. 2003,Characterization of nonmutagenic Cr(III)-DNA interactions,"Exposure of cells or animals to carcinogenic chromium(VI) (Cr(VI)) produces Cr(III)-DNA adducts. The relevance of these lesions to Cr(VI)-induced tumors is unclear. Various Cr(III) complexes have been used to model the products resulting from Cr(VI) metabolism in order to gain mechanistic insights. The purpose of this study was to characterize interactions of Cr(III) complexes with DNA in order to evaluate their use as models for these purposes. The reactivity of DNA with chromic chloride hexahydrate (CrCl(3)) and sodium bis(l-cysteinato)chromium(III) dihydrate (Cr(cys)(2)(-)) was compared to that with cis-diamminedichloroplatinum(II) (cis-platin). Both Cr(III) and Pt(II) cause unwinding of supercoiled DNA that can be visualized as a mobility shift by gel electrophoresis. Chromic chloride was much less distorting than cis-platin, unwinding DNA by only 1-2 degrees, and Cr(cys)(2)(-) interacted with DNA only weakly. Consistent with in vitro studies, CrCl(3) produced Cr-DNA adducts in CHO AA8 cells at levels equivalent to those obtained with Cr(VI), whereas Cr(cys)(2)(-) did not produce significant adducts. Lesions produced by CrCl(3) were not mutagenic in the hypoxanthine-Gua-phosphoribosyl-transferase assay. These data are consistent with CrCl(3) producing a nondistorting lesion, perhaps by association with the phosphate backbone. There are two possible interpretations of these results: Either the Cr(III) products formed by Cr(VI) metabolism are not modeled by CrCl(3) and Cr(cys)(2)(-) complexes, or Cr(III) is not an active species for Cr(VI)-induced DNA damage. This study provides the first structural evidence for Cr(III)-DNA adducts. A molecular understanding of Cr(III)-DNA interactions will be necessary before we can determine their relevance in Cr(VI)-induced cancers.","Characterization of nonmutagenic Cr(III)-DNA interactions Abs: Exposure of cells or animals to carcinogenic chromium(VI) (Cr(VI)) produces Cr(III)-DNA adducts. The relevance of these lesions to Cr(VI)-induced tumors is unclear. Various Cr(III) complexes have been used to model the products resulting from Cr(VI) metabolism in order to gain mechanistic insights. The purpose of this study was to characterize interactions of Cr(III) complexes with DNA in order to evaluate their use as models for these purposes. The reactivity of DNA with chromic chloride hexahydrate (CrCl(3)) and sodium bis(l-cysteinato)chromium(III) dihydrate (Cr(cys)(2)(-)) was compared to that with cis-diamminedichloroplatinum(II) (cis-platin). Both Cr(III) and Pt(II) cause unwinding of supercoiled DNA that can be visualized as a mobility shift by gel electrophoresis. Chromic chloride was much less distorting than cis-platin, unwinding DNA by only 1-2 degrees, and Cr(cys)(2)(-) interacted with DNA only weakly. Consistent with in vitro studies, CrCl(3) produced Cr-DNA adducts in CHO AA8 cells at levels equivalent to those obtained with Cr(VI), whereas Cr(cys)(2)(-) did not produce significant adducts. Lesions produced by CrCl(3) were not mutagenic in the hypoxanthine-Gua-phosphoribosyl-transferase assay. These data are consistent with CrCl(3) producing a nondistorting lesion, perhaps by association with the phosphate backbone. There are two possible interpretations of these results: Either the Cr(III) products formed by Cr(VI) metabolism are not modeled by CrCl(3) and Cr(cys)(2)(-) complexes, or Cr(III) is not an active species for Cr(VI)-induced DNA damage. This study provides the first structural evidence for Cr(III)-DNA adducts. A molecular understanding of Cr(III)-DNA interactions will be necessary before we can determine their relevance in Cr(VI)-induced cancers."
1232029,Codd and  Lay 2003,"Oxochromium(V) species formed with 2,3-dehydro-2-deoxy-N-acetylneuraminic or N-acetylneuraminic (sialic) acids: an in vitro model system of oxochromium(V) species potentially stabilized in the respiratory tract upon inhalation of carcinogenic chromium(VI) compounds","The human respiratory tract is rich in sialoglycoconjugates. These polyfunctional, oxygen-rich molecules stabilize potentially genotoxic oxoCr(V) species, which has relevance to the metabolic fate of carcinogenic Cr(VI) compounds when inhaled as dusts, mists, and fumes during occupational exposure. A series of oxoCr(V) species formed from solutions of Cr(VI) and the reductant, glutathione (GSH), in the presence of an excess of small molecule ligands that model sialoglycoconjugates, either 2,3-dehydro-2-deoxy-N-acetylneuraminic acid (I) or N-acetylneuraminic acid (II), have been characterized as a function of pH value, using electron paramagnetic resonance (EPR) spectroscopy (Cr(V) = d(1)). Where [I] or [II] is in large excess of [Cr(V)-GSH], oxoCr(V)-I or -II species form (g(iso) = 1.97-1.98) via ligand-exchange reactions in which oxygen donor atoms from the carboxylic acid (I), tert-2-hydroxycarboxylato(2-) (II), and/or diolato(2-) groups (I, II) feature in the oxoCr(V) coordination sphere. At pH approximately 7.1 (where [Cr(V)-GSH]:[II] &lt; 1), the oxoCr(V)-II complexes remain EPR active for 24 h (with t(1/2) approximately 380 min). The parent EPR spectrum from oxoCr(V)-I or -II solutions represents the sum of spectra from individual linkage isomers; using EPR spectral simulation procedures, coupled with empirical EPR spectroscopic data for previously characterized oxoCr(V)-hydroxycarboxylato and -diolato species, a signature EPR spectrum has been predicted for each oxoCr(V)-I or -II linkage isomer, with defining g(iso) and (1)H a(iso) values and signal multiplicities. At pH values &gt; 7.0, the major EPR signal (g(iso) approximately 1.980) is a septet, indicating the presence of oxoCr(V)-I or oxoCr(V)-II species with coordination from two O(8),O(9)-diolato(2-) chelates, with six magnetically equivalent protons ((1)H a(iso) approximately 0.7 x 10(-)(4) cm(-)(1)). At pH values &lt; 7.0, where carboxylato binding competes with diolato binding, the species (g(iso) approximately 1.979) most likely feature mixed binding modes from one diolato(2-) and one tert-2-hydroxycarboxylato(2-) chelate (oxoCr(V)-II) or one diolato(2-) chelate, one monodentate carboxylato(1-) group, and aqua and/or hydroxo oxygen donors (oxoCr(V)-I). In I and II, the relative concentration of the oxoCr(V) linkage isomer featuring donation via the O(7),O(8) diolato group is about 1 order of magnitude smaller than the concentration of the O(8),O(9) linkage isomer. The dominance of oxoCr(V)-I or -II linkage isomers with O(8),O(9) donation correlates with the dihedral angle in these isomers (O(9)-C(9)-C(8)-O(8) approximately 65 degrees ) being more favorably disposed toward metal binding, as compared to the O(7),O(8) analogue (O(7)-C(7)-C(8)-O(8) approximately 163 degrees ). These results have important implications with respect to the nature of the oxoCr(V) species that may potentially form in the sialoglycoconjugate-rich environment of the human respiratory tract upon inhalation of carcinogenic Cr(VI) compounds.","Oxochromium(V) species formed with 2,3-dehydro-2-deoxy-N-acetylneuraminic or N-acetylneuraminic (sialic) acids: an in vitro model system of oxochromium(V) species potentially stabilized in the respiratory tract upon inhalation of carcinogenic chromium(VI) compounds Abs: The human respiratory tract is rich in sialoglycoconjugates. These polyfunctional, oxygen-rich molecules stabilize potentially genotoxic oxoCr(V) species, which has relevance to the metabolic fate of carcinogenic Cr(VI) compounds when inhaled as dusts, mists, and fumes during occupational exposure. A series of oxoCr(V) species formed from solutions of Cr(VI) and the reductant, glutathione (GSH), in the presence of an excess of small molecule ligands that model sialoglycoconjugates, either 2,3-dehydro-2-deoxy-N-acetylneuraminic acid (I) or N-acetylneuraminic acid (II), have been characterized as a function of pH value, using electron paramagnetic resonance (EPR) spectroscopy (Cr(V) = d(1)). Where [I] or [II] is in large excess of [Cr(V)-GSH], oxoCr(V)-I or -II species form (g(iso) = 1.97-1.98) via ligand-exchange reactions in which oxygen donor atoms from the carboxylic acid (I), tert-2-hydroxycarboxylato(2-) (II), and/or diolato(2-) groups (I, II) feature in the oxoCr(V) coordination sphere. At pH approximately 7.1 (where [Cr(V)-GSH]:[II] &lt; 1), the oxoCr(V)-II complexes remain EPR active for 24 h (with t(1/2) approximately 380 min). The parent EPR spectrum from oxoCr(V)-I or -II solutions represents the sum of spectra from individual linkage isomers; using EPR spectral simulation procedures, coupled with empirical EPR spectroscopic data for previously characterized oxoCr(V)-hydroxycarboxylato and -diolato species, a signature EPR spectrum has been predicted for each oxoCr(V)-I or -II linkage isomer, with defining g(iso) and (1)H a(iso) values and signal multiplicities. At pH values &gt; 7.0, the major EPR signal (g(iso) approximately 1.980) is a septet, indicating the presence of oxoCr(V)-I or oxoCr(V)-II species with coordination from two O(8),O(9)-diolato(2-) chelates, with six magnetically equivalent protons ((1)H a(iso) approximately 0.7 x 10(-)(4) cm(-)(1)). At pH values &lt; 7.0, where carboxylato binding competes with diolato binding, the species (g(iso) approximately 1.979) most likely feature mixed binding modes from one diolato(2-) and one tert-2-hydroxycarboxylato(2-) chelate (oxoCr(V)-II) or one diolato(2-) chelate, one monodentate carboxylato(1-) group, and aqua and/or hydroxo oxygen donors (oxoCr(V)-I). In I and II, the relative concentration of the oxoCr(V) linkage isomer featuring donation via the O(7),O(8) diolato group is about 1 order of magnitude smaller than the concentration of the O(8),O(9) linkage isomer. The dominance of oxoCr(V)-I or -II linkage isomers with O(8),O(9) donation correlates with the dihedral angle in these isomers (O(9)-C(9)-C(8)-O(8) approximately 65 degrees ) being more favorably disposed toward metal binding, as compared to the O(7),O(8) analogue (O(7)-C(7)-C(8)-O(8) approximately 163 degrees ). These results have important implications with respect to the nature of the oxoCr(V) species that may potentially form in the sialoglycoconjugate-rich environment of the human respiratory tract upon inhalation of carcinogenic Cr(VI) compounds."
1232028,Middleton et al. 2003,Cometabolism of Cr(VI) by Shewanella oneidensis MR-1 produces cell-associated reduced chromium and inhibits growth,"Microbial reduction is a promising strategy for chromium remediation, but the effects of competing electron acceptors are still poorly understood. We investigated chromate (Cr(VI)) reduction in batch cultures of Shewanella oneidensis MR-1 under aerobic and denitrifying conditions and in the absence of an additional electron acceptor. Growth and Cr(VI) removal patterns suggested a cometabolic reduction; in the absence of nitrate or oxygen, MR-1 reduced Cr(VI), but without any increase in viable cell counts and rates gradually decreased when cells were respiked. Only a small fraction (1.6%) of the electrons from lactate were transferred to Cr(VI). The 48-h transformation capacity (Tc) was 0.78 mg (15 micromoles) Cr(VI) reduced. [mg protein](-1) for high levels of Cr(VI) added as a single spike. For low levels of Cr(VI) added sequentially, Tc increased to 3.33 mg (64 micromoles) Cr(VI) reduced. [mg protein](-1), indicating that it is limited by toxicity at higher concentrations. During denitrification and aerobic growth, MR-1 reduced Cr(VI), with much faster rates under denitrifying conditions. Cr(VI) had no effect on nitrate reduction at 6 microM, was strongly inhibitory at 45 microM, and stopped nitrate reduction above 200 microM. Cr(VI) had no effect on aerobic growth at 60 microM, but severely inhibited growth above 150 microM. A factor that likely plays a role in Cr(VI) toxicity is intracellular reduced chromium. Transmission electron microscopy (TEM) and electron energy loss spectroscopy (EELS) of denitrifying cells exposed to Cr(VI) showed reduced chromium precipitates both extracellularly on the cell surface and, for the first time, as electron-dense round globules inside cells.","Cometabolism of Cr(VI) by Shewanella oneidensis MR-1 produces cell-associated reduced chromium and inhibits growth Abs: Microbial reduction is a promising strategy for chromium remediation, but the effects of competing electron acceptors are still poorly understood. We investigated chromate (Cr(VI)) reduction in batch cultures of Shewanella oneidensis MR-1 under aerobic and denitrifying conditions and in the absence of an additional electron acceptor. Growth and Cr(VI) removal patterns suggested a cometabolic reduction; in the absence of nitrate or oxygen, MR-1 reduced Cr(VI), but without any increase in viable cell counts and rates gradually decreased when cells were respiked. Only a small fraction (1.6%) of the electrons from lactate were transferred to Cr(VI). The 48-h transformation capacity (Tc) was 0.78 mg (15 micromoles) Cr(VI) reduced. [mg protein](-1) for high levels of Cr(VI) added as a single spike. For low levels of Cr(VI) added sequentially, Tc increased to 3.33 mg (64 micromoles) Cr(VI) reduced. [mg protein](-1), indicating that it is limited by toxicity at higher concentrations. During denitrification and aerobic growth, MR-1 reduced Cr(VI), with much faster rates under denitrifying conditions. Cr(VI) had no effect on nitrate reduction at 6 microM, was strongly inhibitory at 45 microM, and stopped nitrate reduction above 200 microM. Cr(VI) had no effect on aerobic growth at 60 microM, but severely inhibited growth above 150 microM. A factor that likely plays a role in Cr(VI) toxicity is intracellular reduced chromium. Transmission electron microscopy (TEM) and electron energy loss spectroscopy (EELS) of denitrifying cells exposed to Cr(VI) showed reduced chromium precipitates both extracellularly on the cell surface and, for the first time, as electron-dense round globules inside cells."
1232025,O'Hara et al. 2003,Selective activation of Src family kinases and JNK by low levels of chromium(VI),"Inhaled hexavalent chromium (Cr(VI)) promotes pulmonary disease and lung cancer through poorly defined mechanisms. These mechanisms were studied in A549 lung epithelial cells to investigate the hypothesis that nontoxic Cr(VI) exposures selectively activate cell signaling that shifts the balance of gene transcription. These studies demonstrated that nontoxic doses of Cr(VI) (10 microM) increased reactive oxygen species and selectively activated c-Jun N-terminal kinase (JNK), relative to ERK or p38 MAP kinase. In contrast, only toxic, nonselective levels of exogenous oxidants stimulated JNK. However, JNK activation in response to Cr(VI) and exogenous H(2)O(2) (1 mM) shared requirements for intracellular thiol oxidation, activation of Src family kinases, and p130(cas) (Cas). Cr(VI) did not mimic H(2)O(2)-mediated stimulation of JNK in fibroblasts containing only Src and did not activate Src or Yes in A549 cells. Instead, Fyn and Lck were activated in A549 cells, indicating activation of specific Src family kinases in response to Cr(VI). Finally, Cr(VI) was demonstrated to directly activate purified Fyn in vitro and the majority of this activation did not require oxidant generation. These data suggest that nontoxic levels of Cr(VI), which can shift patterns of gene transcription, are selective in their activation of cell signaling and that Cr(VI) can directly activate Src family kinases independently of reactive oxygen species generation.","Selective activation of Src family kinases and JNK by low levels of chromium(VI) Abs: Inhaled hexavalent chromium (Cr(VI)) promotes pulmonary disease and lung cancer through poorly defined mechanisms. These mechanisms were studied in A549 lung epithelial cells to investigate the hypothesis that nontoxic Cr(VI) exposures selectively activate cell signaling that shifts the balance of gene transcription. These studies demonstrated that nontoxic doses of Cr(VI) (10 microM) increased reactive oxygen species and selectively activated c-Jun N-terminal kinase (JNK), relative to ERK or p38 MAP kinase. In contrast, only toxic, nonselective levels of exogenous oxidants stimulated JNK. However, JNK activation in response to Cr(VI) and exogenous H(2)O(2) (1 mM) shared requirements for intracellular thiol oxidation, activation of Src family kinases, and p130(cas) (Cas). Cr(VI) did not mimic H(2)O(2)-mediated stimulation of JNK in fibroblasts containing only Src and did not activate Src or Yes in A549 cells. Instead, Fyn and Lck were activated in A549 cells, indicating activation of specific Src family kinases in response to Cr(VI). Finally, Cr(VI) was demonstrated to directly activate purified Fyn in vitro and the majority of this activation did not require oxidant generation. These data suggest that nontoxic levels of Cr(VI), which can shift patterns of gene transcription, are selective in their activation of cell signaling and that Cr(VI) can directly activate Src family kinases independently of reactive oxygen species generation."
1232024,Camargo et al. 2003,Chromate reduction by chromium-resistant bacteria isolated from soils contaminated with dichromate,"Extensive use of hexavalent chromium [Cr(VI)] in various industrial applications has caused substantial environmental contamination. Chromium-resistant bacteria isolated from soils can be used to remove toxic Cr(VI) from contaminated environments. This study was conducted to isolate chromium-resistant bacteria from soils contaminated with dichromate and describes the effects of some environmental factors such as pH, temperature, and time on Cr(VI) reduction and resistance. We found that chromium-resistant bacteria can tolerate 2500 mg L(-1) Cr(VI), but most of the isolates tolerated and reduced Cr(VI) at concentrations lower than 1500 mg L(-1). Chromate reduction activity of whole cells was detected in five isolates. Most of these isolates belong to the genus Bacillus as identified by the 16S rRNA gene sequencing. Maximal Cr(VI) reduction was observed at the optimum pH (7.0-9.0) and temperature (30 degrees C) of growth. One bacterial isolate (Bacillus sp. ES 29) was able to aerobically reduce 90% of Cr(VI) in six hours. The Cr(VI) reduction activity of the whole cells of five isolates had a K(M) of 0.271 (2.61 mM) to 1.51 mg L(-1) (14.50 mM) and a V(max) of 88.4 (14.17 nmol min(-1)) to 489 mg L9-1) h(-1) (78.36 nmol min(-1)). Our consortia and monocultures of these isolates can be useful for Cr(VI) detoxification at low and high concentrations in Cr(VI)-contaminated environments and under a wide range of environmental conditions.","Chromate reduction by chromium-resistant bacteria isolated from soils contaminated with dichromate Abs: Extensive use of hexavalent chromium [Cr(VI)] in various industrial applications has caused substantial environmental contamination. Chromium-resistant bacteria isolated from soils can be used to remove toxic Cr(VI) from contaminated environments. This study was conducted to isolate chromium-resistant bacteria from soils contaminated with dichromate and describes the effects of some environmental factors such as pH, temperature, and time on Cr(VI) reduction and resistance. We found that chromium-resistant bacteria can tolerate 2500 mg L(-1) Cr(VI), but most of the isolates tolerated and reduced Cr(VI) at concentrations lower than 1500 mg L(-1). Chromate reduction activity of whole cells was detected in five isolates. Most of these isolates belong to the genus Bacillus as identified by the 16S rRNA gene sequencing. Maximal Cr(VI) reduction was observed at the optimum pH (7.0-9.0) and temperature (30 degrees C) of growth. One bacterial isolate (Bacillus sp. ES 29) was able to aerobically reduce 90% of Cr(VI) in six hours. The Cr(VI) reduction activity of the whole cells of five isolates had a K(M) of 0.271 (2.61 mM) to 1.51 mg L(-1) (14.50 mM) and a V(max) of 88.4 (14.17 nmol min(-1)) to 489 mg L9-1) h(-1) (78.36 nmol min(-1)). Our consortia and monocultures of these isolates can be useful for Cr(VI) detoxification at low and high concentrations in Cr(VI)-contaminated environments and under a wide range of environmental conditions."
1232023,Baig et al. 2003,Laboratory scale studies on removal of chromium from industrial wastes,"Chromium being one of the major toxic pollutants is discharged from electroplating and chrome tanning processes and is also found in the effluents of dyes, paint pigments, manufacturing units etc. Chromium exists in aqueous systems in both trivalent (Cr(3+)) and hexavalent (Cr(6+)) forms. The hexavalent form is carcinogenic and toxic to aquatic life, whereas Cr(3+) is however comparatively less toxic. This study was undertaken to investigate the total chromium removal from industrial effluents by chemical means in order to achieve the Pakistan NEQS level of 1 mg/L by the methods of reduction and precipitation. The study was conducted in four phases. In phase I, the optimum pH and cost effective reducing agent among the four popular commercial chemicals was selected. As a result, pH of 2 was found to be most suitable and sodium meta bisulfate was found to be the most cost effective reducing agent respectively. Phase II showed that lower dose of sodium meta bisulfate was sufficient to obtain 100% efficiency in reducing Cr(6+) to Cr(3+), and it was noted that reaction time had no significance in the whole process. A design curve for reduction process was established which can act as a tool for treatment of industrial effluents. Phase III studies indicated the best pH was 8.5 for precipitation of Cr(3+) to chromium hydroxide by using lime. An efficiency of 100% was achievable and a settling time of 30 minutes produced clear effluent. Finally in Phase IV actual waste samples from chrome tanning and electroplating industries, when precipitated at pH of 12 gave 100% efficiency at a settling time of 30 minutes and confined that chemical means of reduction and precipitation is a feasible and viable solution for treating chromium wastes from industries.","Laboratory scale studies on removal of chromium from industrial wastes Abs: Chromium being one of the major toxic pollutants is discharged from electroplating and chrome tanning processes and is also found in the effluents of dyes, paint pigments, manufacturing units etc. Chromium exists in aqueous systems in both trivalent (Cr(3+)) and hexavalent (Cr(6+)) forms. The hexavalent form is carcinogenic and toxic to aquatic life, whereas Cr(3+) is however comparatively less toxic. This study was undertaken to investigate the total chromium removal from industrial effluents by chemical means in order to achieve the Pakistan NEQS level of 1 mg/L by the methods of reduction and precipitation. The study was conducted in four phases. In phase I, the optimum pH and cost effective reducing agent among the four popular commercial chemicals was selected. As a result, pH of 2 was found to be most suitable and sodium meta bisulfate was found to be the most cost effective reducing agent respectively. Phase II showed that lower dose of sodium meta bisulfate was sufficient to obtain 100% efficiency in reducing Cr(6+) to Cr(3+), and it was noted that reaction time had no significance in the whole process. A design curve for reduction process was established which can act as a tool for treatment of industrial effluents. Phase III studies indicated the best pH was 8.5 for precipitation of Cr(3+) to chromium hydroxide by using lime. An efficiency of 100% was achievable and a settling time of 30 minutes produced clear effluent. Finally in Phase IV actual waste samples from chrome tanning and electroplating industries, when precipitated at pH of 12 gave 100% efficiency at a settling time of 30 minutes and confined that chemical means of reduction and precipitation is a feasible and viable solution for treating chromium wastes from industries."
1232022,Lee et al. 2003,Use of waste iron metal for removal of Cr(VI) from water,"Cr(VI) removal from water was evaluated using waste iron particles in batch experimental mode. The reaction rates were inversely proportional to the initial Cr(VI) concentrations, and the reaction rates of Cr(VI) removal with the waste iron metal were faster than those with Peerless iron, a commercial zero-valent iron. The loss in iron reactivity due to the oxidation, from Fe(0) to Fe(II), ultimately to Fe(III), could be recovered by adding iron-reducing consortium (IRC) to the oxidized iron. Bacterial reduction of Cr(VI) also helped to decrease the aqueous concentration of Cr(VI), but the reduction of oxidized iron by IRC and the consequent reduction of Cr(VI) to Cr(III) by the reduced iron was more significant. Thus, reusing waste iron metal for Cr(VI) removal can reduce the cost of reactive media. Furthermore, the addition of IRC to the waste iron metal can accelerate the removal rate of Cr(VI), and can recover the reactivity of irons which were oxidized by Cr(VI).","Use of waste iron metal for removal of Cr(VI) from water Abs: Cr(VI) removal from water was evaluated using waste iron particles in batch experimental mode. The reaction rates were inversely proportional to the initial Cr(VI) concentrations, and the reaction rates of Cr(VI) removal with the waste iron metal were faster than those with Peerless iron, a commercial zero-valent iron. The loss in iron reactivity due to the oxidation, from Fe(0) to Fe(II), ultimately to Fe(III), could be recovered by adding iron-reducing consortium (IRC) to the oxidized iron. Bacterial reduction of Cr(VI) also helped to decrease the aqueous concentration of Cr(VI), but the reduction of oxidized iron by IRC and the consequent reduction of Cr(VI) to Cr(III) by the reduced iron was more significant. Thus, reusing waste iron metal for Cr(VI) removal can reduce the cost of reactive media. Furthermore, the addition of IRC to the waste iron metal can accelerate the removal rate of Cr(VI), and can recover the reactivity of irons which were oxidized by Cr(VI)."
1232020,Renner 2003,Allegations of manipulation lead to withdrawal of Cr(VI) report,,Allegations of manipulation lead to withdrawal of Cr(VI) report Abs: 
1232017,Howe et al. 2003,"Localization and speciation of chromium in subterranean clover using XRF, XANES, and EPR spectroscopy","Optimization of phytoremediation and assessment of potential health hazards from metals in the environment requires an understanding of absorption, localization, and transport of the target metal by plants. The objectives of this study were to localize Cr and determine the oxidation state and possible complexation mode of Cr in intact plant tissue by means of XANES, synchrotron XRF microprobe spectroscopy, and EPR spectroscopy. Subterranean clover (Trifolium brachycalycinum) was grown hydroponically with Cr(VI) (0.04-2.0 mmol L(-1)) and compared with plants grown without Cr and with inorganic Cr(III) and various Cr(III)-organic sources. The uptake, translocation, and form of Cr in the plant were dependent on the form and concentration of supplied Cr. Chromium was found predominately in the +3 oxidation state, regardless of the Cr source supplied to the plant, though at high Cr(VI) treatment concentrations, Cr(VI) and Cr(V) were also observed. At low Cr(VI) concentrations, the plant effectively reduced the toxic Cr(VI) to less toxic Cr(III), which was observed both as a Cr(III) hydroxide phase at the roots and as a Cr(III)-organic complex in the roots and shoots. At low Cr(VI) treatment concentrations, Cr in the leaves was observed predominately around the leaf margins, while at higher concentrations Cr was accumulated at leaf veins.","Localization and speciation of chromium in subterranean clover using XRF, XANES, and EPR spectroscopy Abs: Optimization of phytoremediation and assessment of potential health hazards from metals in the environment requires an understanding of absorption, localization, and transport of the target metal by plants. The objectives of this study were to localize Cr and determine the oxidation state and possible complexation mode of Cr in intact plant tissue by means of XANES, synchrotron XRF microprobe spectroscopy, and EPR spectroscopy. Subterranean clover (Trifolium brachycalycinum) was grown hydroponically with Cr(VI) (0.04-2.0 mmol L(-1)) and compared with plants grown without Cr and with inorganic Cr(III) and various Cr(III)-organic sources. The uptake, translocation, and form of Cr in the plant were dependent on the form and concentration of supplied Cr. Chromium was found predominately in the +3 oxidation state, regardless of the Cr source supplied to the plant, though at high Cr(VI) treatment concentrations, Cr(VI) and Cr(V) were also observed. At low Cr(VI) concentrations, the plant effectively reduced the toxic Cr(VI) to less toxic Cr(III), which was observed both as a Cr(III) hydroxide phase at the roots and as a Cr(III)-organic complex in the roots and shoots. At low Cr(VI) treatment concentrations, Cr in the leaves was observed predominately around the leaf margins, while at higher concentrations Cr was accumulated at leaf veins."
1232016,Dupont and  Guillon 2003,Removal of hexavalent chromium with a lignocellulosic substrate extracted from wheat bran,"In this paper, a new recovery system of the toxic hexavalent chromium Cr(VI) is proposed that uses a lignocellulosic substrate derived from the industrial treatment process of wheat bran. We studied the adsorption mechanism of Cr(VI) onto the lignocellulosic substrate and showed that the adsorption reaction consumes a large amount of protons goes along the reduction of Cr(VI) into Cr(III). The oxidation of lignin moieties takes place concurrently to the chromium reduction and leads to the formation of hydroxyl and carboxyl functions. The latter contribute to an increase in the number of ion-exchange sites for the reduced chromium. The maximum adsorption capacity for hexavalent chromium was found at about 35 mg g(-1) in an acidic medium. This is comparable to other natural substrates and ordinary adsorbents.","Removal of hexavalent chromium with a lignocellulosic substrate extracted from wheat bran Abs: In this paper, a new recovery system of the toxic hexavalent chromium Cr(VI) is proposed that uses a lignocellulosic substrate derived from the industrial treatment process of wheat bran. We studied the adsorption mechanism of Cr(VI) onto the lignocellulosic substrate and showed that the adsorption reaction consumes a large amount of protons goes along the reduction of Cr(VI) into Cr(III). The oxidation of lignin moieties takes place concurrently to the chromium reduction and leads to the formation of hydroxyl and carboxyl functions. The latter contribute to an increase in the number of ion-exchange sites for the reduced chromium. The maximum adsorption capacity for hexavalent chromium was found at about 35 mg g(-1) in an acidic medium. This is comparable to other natural substrates and ordinary adsorbents."
1232014,Lee et al. 2003,Treatment of Cr(VI) and phenol by illuminated TiO2,"Industrial wastewater from organic chemical manufacturing and metal plating industries may contain significant amounts of refractory organic matter and heavy metals. Heavy metals such as Cr(VI) and refractory organic matter like phenol were simultaneously removed by reduction and mineralization, respectively, during photocatalytic process. Therefore, this study was carried out to evaluate the effects of phenol on the removal of Cr(VI) in several environmental conditions. Cr(VI) and phenol were more effectively eliminated in UV/TiO2 condition than either by UV or TiO2-alone. The removal efficiencies of Cr(VI) increased as the pH of the TiO2 slurry decreased, the concentration of phenol increased up to 10 mg L(-1), and nitrogen gas was used. Otherwise, the removal efficiencies of phenol were higher at O2-purged system and neutral pH. Without regard to purging gases, complete Cr(VI) removal was observed at pH 4 after 80 min while 90% phenol destruction and 60% mineralization were found after 120 min. It wasfound that application of photocatalytic reaction by using illuminated TiO2 to treat wastewater containing both Cr(VI) and phenol was possible.","Treatment of Cr(VI) and phenol by illuminated TiO2 Abs: Industrial wastewater from organic chemical manufacturing and metal plating industries may contain significant amounts of refractory organic matter and heavy metals. Heavy metals such as Cr(VI) and refractory organic matter like phenol were simultaneously removed by reduction and mineralization, respectively, during photocatalytic process. Therefore, this study was carried out to evaluate the effects of phenol on the removal of Cr(VI) in several environmental conditions. Cr(VI) and phenol were more effectively eliminated in UV/TiO2 condition than either by UV or TiO2-alone. The removal efficiencies of Cr(VI) increased as the pH of the TiO2 slurry decreased, the concentration of phenol increased up to 10 mg L(-1), and nitrogen gas was used. Otherwise, the removal efficiencies of phenol were higher at O2-purged system and neutral pH. Without regard to purging gases, complete Cr(VI) removal was observed at pH 4 after 80 min while 90% phenol destruction and 60% mineralization were found after 120 min. It wasfound that application of photocatalytic reaction by using illuminated TiO2 to treat wastewater containing both Cr(VI) and phenol was possible."
1232013,Tokunaga et al. 2003,In situ reduction of chromium(VI) in heavily contaminated soils through organic carbon amendment,"Chromium has become an important soil contaminant at many sites, and facilitating in situ reduction of toxic Cr(VI) to nontoxic Cr(III) is becoming an attractive remediation strategy. Acceleration of Cr(VI) reduction in soils by addition of organic carbon was tested in columns pretreated with solutions containing 1000 and 10 000 mg L(-1) Cr(VI) to evaluate potential in situ remediation of highly contaminated soils. Solutions containing 0,800, or 4000 mg L(-1) organic carbon in the form of tryptic soy broth or lactate were diffused into the Cr(VI)-contaminated soils. Changes in Cr oxidation state were monitored through periodic micro-XANES analyses of soil columns. Effective first-order reduction rate constants ranged from 1.4 x 10(-8) to 1.5 x 10(-7) s(-1), with higher values obtained for lower levels of initial Cr(VI) and higher levels of organic carbon. Comparisons with sterile soils showed that microbially dependent processes were largely responsible for Cr(VI) reduction, except in the soils initially exposed to 10 000 mg L(-1) Cr(VI) solutions that receive little (800 mg L(-1)) or no organic carbon. However, the microbial populations (&lt; or = 2.1 x 10(5) g(-1)) in the viable soils are probably too low for direct enzymatic Cr(VI) reduction to be important. Thus, synergistic effects sustained in whole soil systems may have accounted for most of the observed reduction. These results show that acceleration of in situ Cr(VI) reduction with addition of organic carbon is possible in even heavily contaminated soils and suggest that microbially dependent reduction pathways can be dominant.","In situ reduction of chromium(VI) in heavily contaminated soils through organic carbon amendment Abs: Chromium has become an important soil contaminant at many sites, and facilitating in situ reduction of toxic Cr(VI) to nontoxic Cr(III) is becoming an attractive remediation strategy. Acceleration of Cr(VI) reduction in soils by addition of organic carbon was tested in columns pretreated with solutions containing 1000 and 10 000 mg L(-1) Cr(VI) to evaluate potential in situ remediation of highly contaminated soils. Solutions containing 0,800, or 4000 mg L(-1) organic carbon in the form of tryptic soy broth or lactate were diffused into the Cr(VI)-contaminated soils. Changes in Cr oxidation state were monitored through periodic micro-XANES analyses of soil columns. Effective first-order reduction rate constants ranged from 1.4 x 10(-8) to 1.5 x 10(-7) s(-1), with higher values obtained for lower levels of initial Cr(VI) and higher levels of organic carbon. Comparisons with sterile soils showed that microbially dependent processes were largely responsible for Cr(VI) reduction, except in the soils initially exposed to 10 000 mg L(-1) Cr(VI) solutions that receive little (800 mg L(-1)) or no organic carbon. However, the microbial populations (&lt; or = 2.1 x 10(5) g(-1)) in the viable soils are probably too low for direct enzymatic Cr(VI) reduction to be important. Thus, synergistic effects sustained in whole soil systems may have accounted for most of the observed reduction. These results show that acceleration of in situ Cr(VI) reduction with addition of organic carbon is possible in even heavily contaminated soils and suggest that microbially dependent reduction pathways can be dominant."
1232012,Sultan and  Hasnain 2003,Pseudomonad strains exhibiting high level Cr(VI) resistance and Cr(VI) detoxification potential,,Pseudomonad strains exhibiting high level Cr(VI) resistance and Cr(VI) detoxification potential Abs: 
1232011,Gaberell et al. 2003,Role of dissolved organic matter composition on the photoreduction of Cr(VI) to Cr(III) in the presence of iron,"The photochemical reduction of Cr(VI) by iron and aquatic dissolved organic matter (DOM) was investigated. DOM sampled from a number of surface waters (a eutrophic wetland, a blackwater stream, and river water from a mix-use watershed) was used in this study. Moreover, a fulvic acid from Lake Fryxell, Antarctica, was also used to represent a DOM derived from a strictly autochthonous source. Cr(VI) reduction to Cr(III) at pH 5.5 was observed for all target DOMs used in this study, but rates varied widely. In general, photoreduction rates increased with increasing iron concentrations, but the type of DOM appeared to influence the kinetics to a larger degree. The rate of reduction was significantly greater for DOM derived from terrestrial systems than from predominantly autochthonous materials even if additional iron was added to the later. A positive correlation was observed between rates of Cr(VI) photoreduction and properties of the isolated DOM samples whereby faster reduction was observed for larger more aromatic substrates. On the basis of the fast rates reported for the dark reduction of Cr(VI) to Cr(III) by Fe(II)-organic ligands, we hypothesize that the rate-limiting step in these reactions is the photoreduction of Fe(III) to Fe(II) by a ligand-to-metal charge-transfer pathway after absorption of light by Fe(III)-DOM complexes or by reduction of Fe(III) by superoxide or other intermediates formed after light absorption by DOM. Thus, the rate of Cr(VI) photoreduction to Cr(III) in natural sunlit waters is dependent upon both the amount of iron present and the nature of the dissolved organic matter substrate.","Role of dissolved organic matter composition on the photoreduction of Cr(VI) to Cr(III) in the presence of iron Abs: The photochemical reduction of Cr(VI) by iron and aquatic dissolved organic matter (DOM) was investigated. DOM sampled from a number of surface waters (a eutrophic wetland, a blackwater stream, and river water from a mix-use watershed) was used in this study. Moreover, a fulvic acid from Lake Fryxell, Antarctica, was also used to represent a DOM derived from a strictly autochthonous source. Cr(VI) reduction to Cr(III) at pH 5.5 was observed for all target DOMs used in this study, but rates varied widely. In general, photoreduction rates increased with increasing iron concentrations, but the type of DOM appeared to influence the kinetics to a larger degree. The rate of reduction was significantly greater for DOM derived from terrestrial systems than from predominantly autochthonous materials even if additional iron was added to the later. A positive correlation was observed between rates of Cr(VI) photoreduction and properties of the isolated DOM samples whereby faster reduction was observed for larger more aromatic substrates. On the basis of the fast rates reported for the dark reduction of Cr(VI) to Cr(III) by Fe(II)-organic ligands, we hypothesize that the rate-limiting step in these reactions is the photoreduction of Fe(III) to Fe(II) by a ligand-to-metal charge-transfer pathway after absorption of light by Fe(III)-DOM complexes or by reduction of Fe(III) by superoxide or other intermediates formed after light absorption by DOM. Thus, the rate of Cr(VI) photoreduction to Cr(III) in natural sunlit waters is dependent upon both the amount of iron present and the nature of the dissolved organic matter substrate."
1232008,Kalabegishvili et al. 2003,Electron spin resonance study of chromium(V) formation and decomposition by basalt-inhabiting bacteria,"Bacterial reduction of Cr(VI) to Cr(III) compounds may produce reactive intermediates Cr(V) and Cr(IV), which can affect the mobility and toxicity of chromium in environments. To address this important subject, we conducted an electron spin resonance (ESR) study to understand the kinetics of the formation and decomposition of Cr(V) during Cr(VI) reduction by different gram-positive Cr(VI)-tolerant bacteria, which were isolated from polluted basalts from the United States of America and the Republic of Georgia. Results from our batch experiments show that during Cr(VI) reduction, the macromolecules at the cell wall of these bacteria could act as an electron donor to Cr(VI) to form a stable square-pyramidal Cr(V) complexes, which were reduced further probably via a one-electron transfer pathway to form Cr(IV) and Cr(III) compounds. The Cr(V) peak at the ESR spectrum possessed superhyperfine splitting characteristic of the Cr(V) complexes with diol-containing molecules. It appears that the kinetics of Cr(V) formation and decomposition depended on the bacterial growth phase and on the species. Both formation and decomposition of Cr(V) occurred more quickly when Cr(VI) was added at the exponential phase. In comparison with other gram-positive bacteria from the republic of Georgia, the formation and decomposition of Cr(V) in Arthrobacter species from the Unites States was significantly slower.","Electron spin resonance study of chromium(V) formation and decomposition by basalt-inhabiting bacteria Abs: Bacterial reduction of Cr(VI) to Cr(III) compounds may produce reactive intermediates Cr(V) and Cr(IV), which can affect the mobility and toxicity of chromium in environments. To address this important subject, we conducted an electron spin resonance (ESR) study to understand the kinetics of the formation and decomposition of Cr(V) during Cr(VI) reduction by different gram-positive Cr(VI)-tolerant bacteria, which were isolated from polluted basalts from the United States of America and the Republic of Georgia. Results from our batch experiments show that during Cr(VI) reduction, the macromolecules at the cell wall of these bacteria could act as an electron donor to Cr(VI) to form a stable square-pyramidal Cr(V) complexes, which were reduced further probably via a one-electron transfer pathway to form Cr(IV) and Cr(III) compounds. The Cr(V) peak at the ESR spectrum possessed superhyperfine splitting characteristic of the Cr(V) complexes with diol-containing molecules. It appears that the kinetics of Cr(V) formation and decomposition depended on the bacterial growth phase and on the species. Both formation and decomposition of Cr(V) occurred more quickly when Cr(VI) was added at the exponential phase. In comparison with other gram-positive bacteria from the republic of Georgia, the formation and decomposition of Cr(V) in Arthrobacter species from the Unites States was significantly slower."
1232007,Hua and  Deng 2003,Influences of water vapor on Cr(VI) reduction by gaseous hydrogen sulfide,"In Situ Gaseous Reduction (ISGR) using hydrogen sulfide (H2S) is a technology developed for soil remediation by reductive immobilization of contaminants such as hexavalent chromium (Cr(VI)). Deploying the technology requires us to obtain a much-improved understanding of the interactions among the contaminants, H2S, and various soil components. In this study, Cr(VI) reduction by gaseous H2S was examined under various relative humidities (0-96.7%), concentrations of Cr(VI) (127-475 microg/g of solid), and H2S (0-800 ppm(v)) and by using Cr(VI) compounds with different solubilities. Glass beads with various average diameters (GA = 0.600 mm; GB = 0.212-0.300 mm; and GC = 0.106 mm) and silica (SA = 0.075-0.150 mm) were used as matrices to support K2CrO4, CaCrO4, PbCrO4, or BaCrO4, and reduction of these compounds by gaseous H2S was monitored by Cr(VI) analysis following extractions with distilled water or hot alkali solution. The results showed that Cr(VI) reduction relied on both the relative humidity of the gaseous stream and the size of particles onto which Cr(VI) was deposited. The relative humidity required for fast Cr(VI) reduction was 85% for GA, 61% for GB, 6% for SA, and 0% for GC. It was believed that a water film formed on the particle surfaces under appropriate humidity conditions, resulting in Cr(VI) compound dissolution and subsequent reduction. For nonsoluble Cr(VI) compounds including PbCrO4 and BaCrO4, no reduction by H2S was observed, even at high relative humidity (96.7%), due to lack of dissolution. This study indicated that ISGR treatment in soils requires appropriate moisture content in the subsurface or maintaining a suitable humidity in the treatment gas stream to maximize chromium immobilization.","Influences of water vapor on Cr(VI) reduction by gaseous hydrogen sulfide Abs: In Situ Gaseous Reduction (ISGR) using hydrogen sulfide (H2S) is a technology developed for soil remediation by reductive immobilization of contaminants such as hexavalent chromium (Cr(VI)). Deploying the technology requires us to obtain a much-improved understanding of the interactions among the contaminants, H2S, and various soil components. In this study, Cr(VI) reduction by gaseous H2S was examined under various relative humidities (0-96.7%), concentrations of Cr(VI) (127-475 microg/g of solid), and H2S (0-800 ppm(v)) and by using Cr(VI) compounds with different solubilities. Glass beads with various average diameters (GA = 0.600 mm; GB = 0.212-0.300 mm; and GC = 0.106 mm) and silica (SA = 0.075-0.150 mm) were used as matrices to support K2CrO4, CaCrO4, PbCrO4, or BaCrO4, and reduction of these compounds by gaseous H2S was monitored by Cr(VI) analysis following extractions with distilled water or hot alkali solution. The results showed that Cr(VI) reduction relied on both the relative humidity of the gaseous stream and the size of particles onto which Cr(VI) was deposited. The relative humidity required for fast Cr(VI) reduction was 85% for GA, 61% for GB, 6% for SA, and 0% for GC. It was believed that a water film formed on the particle surfaces under appropriate humidity conditions, resulting in Cr(VI) compound dissolution and subsequent reduction. For nonsoluble Cr(VI) compounds including PbCrO4 and BaCrO4, no reduction by H2S was observed, even at high relative humidity (96.7%), due to lack of dissolution. This study indicated that ISGR treatment in soils requires appropriate moisture content in the subsurface or maintaining a suitable humidity in the treatment gas stream to maximize chromium immobilization."
1232006,Pagano et al. 2003,Oxidative stress-related mechanisms are associated with xenobiotics exerting excess toxicity to Fanconi anemia cells,"An extensive body of evidence has demonstrated the sensitivity of Fanconi anemia (FA) cells to redox-active xenobiotics, such as mitomycin C, diepoxybutane, cisplatin, and 8-methoxypsoralen plus ultraviolet irradiation, with toxicity mechanisms that are consistent with a deficiency of FA cells in coping with oxidative stress. A recent study has reported on excess sensitivity of FA complementation A group cells to chromium VI [Cr(VI)] toxicity, by postulating that a deficiency in Cr-DNA cross-link removal by FA cells and formation of Cr(VI)-associated cross-links may be the mechanism of Cr(VI)-induced cytotoxicity. However, the report failed to demonstrate any enhanced Cr uptake or, especially, any increase in Cr-DNA adducts. Thus, well-established findings on Cr(VI)-induced oxidative stress may explain excess sensitivity of FA cells to Cr(VI) in terms of its inability to cope with the Cr(VI)-induced prooxidant state.","Oxidative stress-related mechanisms are associated with xenobiotics exerting excess toxicity to Fanconi anemia cells Abs: An extensive body of evidence has demonstrated the sensitivity of Fanconi anemia (FA) cells to redox-active xenobiotics, such as mitomycin C, diepoxybutane, cisplatin, and 8-methoxypsoralen plus ultraviolet irradiation, with toxicity mechanisms that are consistent with a deficiency of FA cells in coping with oxidative stress. A recent study has reported on excess sensitivity of FA complementation A group cells to chromium VI [Cr(VI)] toxicity, by postulating that a deficiency in Cr-DNA cross-link removal by FA cells and formation of Cr(VI)-associated cross-links may be the mechanism of Cr(VI)-induced cytotoxicity. However, the report failed to demonstrate any enhanced Cr uptake or, especially, any increase in Cr-DNA adducts. Thus, well-established findings on Cr(VI)-induced oxidative stress may explain excess sensitivity of FA cells to Cr(VI) in terms of its inability to cope with the Cr(VI)-induced prooxidant state."
1232005,Yoon et al. 2003,Fume generation and content of total chromium and hexavalent chromium in flux-cored arc welding,"This study was performed to investigate the fume generation rates (FGRs) and the concentrations of total chromium and hexavalent chromium when stainless steel was welded using flux-cored arc welding (FCAW) with CO2 gas. FGRs and concentrations of total chromium and hexavalent chromium were quantified using a method recommended by the American Welding Society, inductively coupled plasma-atomic emission spectroscopy (NIOSH Method 7300) and ion chromatography (modified NIOSH Method 7604), respectively. The amount of total fume generated was significantly related to the level of input power. The ranges of FGR were 189-344, 389-698 and 682-1157 mg/min at low, optimal and high input power, respectively. It was found that the FGRs increased with input power by an exponent of 1.19, and increased with current by an exponent of 1.75. The ranges of total chromium fume generation rate (FGRCr) were 3.83-8.27, 12.75-37.25 and 38.79-76.46 mg/min at low, optimal and high input power, respectively. The ranges of hexavalent chromium fume generation rate (FGRCr6+) were 0.46-2.89, 0.76-6.28 and 1.70-11.21 mg/min at low, optimal and high input power, respectively. Thus, hexavalent chromium, which is known to be a carcinogen, generated 1.9 (1.0-2.7) times and 3.7 (2.4-5.0) times as the input power increased from low to optimal and low to high, respectively. As a function of input power, the concentration of total chromium in the fume increased from 1.57-2.65 to 5.45-8.13% while the concentration of hexavalent chromium ranged from 0.15 to 1.08%. The soluble fraction of hexavalent chromium produced by FCAW was approximately 80-90% of total hexavalent chromium. The concentration of total chromium and the solubility of hexavalent chromium were similar to those reported from other studies of shielded metal arc welding fumes, and the concentration of hexavalent chromium was similar to that obtained for metal inert gas-welding fumes.","Fume generation and content of total chromium and hexavalent chromium in flux-cored arc welding Abs: This study was performed to investigate the fume generation rates (FGRs) and the concentrations of total chromium and hexavalent chromium when stainless steel was welded using flux-cored arc welding (FCAW) with CO2 gas. FGRs and concentrations of total chromium and hexavalent chromium were quantified using a method recommended by the American Welding Society, inductively coupled plasma-atomic emission spectroscopy (NIOSH Method 7300) and ion chromatography (modified NIOSH Method 7604), respectively. The amount of total fume generated was significantly related to the level of input power. The ranges of FGR were 189-344, 389-698 and 682-1157 mg/min at low, optimal and high input power, respectively. It was found that the FGRs increased with input power by an exponent of 1.19, and increased with current by an exponent of 1.75. The ranges of total chromium fume generation rate (FGRCr) were 3.83-8.27, 12.75-37.25 and 38.79-76.46 mg/min at low, optimal and high input power, respectively. The ranges of hexavalent chromium fume generation rate (FGRCr6+) were 0.46-2.89, 0.76-6.28 and 1.70-11.21 mg/min at low, optimal and high input power, respectively. Thus, hexavalent chromium, which is known to be a carcinogen, generated 1.9 (1.0-2.7) times and 3.7 (2.4-5.0) times as the input power increased from low to optimal and low to high, respectively. As a function of input power, the concentration of total chromium in the fume increased from 1.57-2.65 to 5.45-8.13% while the concentration of hexavalent chromium ranged from 0.15 to 1.08%. The soluble fraction of hexavalent chromium produced by FCAW was approximately 80-90% of total hexavalent chromium. The concentration of total chromium and the solubility of hexavalent chromium were similar to those reported from other studies of shielded metal arc welding fumes, and the concentration of hexavalent chromium was similar to that obtained for metal inert gas-welding fumes."
1232003,O'Brien et al. 2003,"Complexities of chromium carcinogenesis: role of cellular response, repair and recovery mechanisms","Certain hexavalent chromium (Cr(VI))-containing compounds are recognized occupational human lung carcinogens and may pose an environmental health risk. The carcinogenicity of Cr(VI) is targeted to particulate forms of moderate to low solubility. Soluble Cr(VI) oxyanions in the immediate cellular microenvironment traverse the cell membrane by non-specific anionic transporters. Cr(VI) is reductively metabolized within cells by agents including ascorbic acid (Asc), glutathione (GSH) and cysteine (Cys). During Cr(VI) reduction, a diverse range of genetic lesions are generated including Cr-DNA binary (mono) adducts, Cr-DNA ternary adducts, DNA protein crosslinks (DPCs), bi-functional (DNA interstrand crosslinks (ICLs)) adducts, single-strand breaks (SSBs) and oxidized bases. Some forms of Cr damage, such as ICLs, present physical barriers to DNA replication/transcription and, thus, likely promote a terminal cell fate such as apoptosis or terminal growth arrest. Other lesions, such as ternary DNA adducts, are potentially pre-mutagenic. Cr(VI) exposure elicits a classical DNA damage response within cells including activation of the p53 signaling pathway and cell cycle arrest or apoptosis. Moreover, Cr(VI) also induces the ATM-dependent DNA damage response pathway which is paradoxically required for both apoptosis and survival after Cr(VI) insult. In yeast, moderately cytotoxic concentrations of Cr(VI) result in an initial G1 arrest and delayed S phase progression, whereas less toxic levels of Cr(VI) induce G2 arrest, which requires homologous recombination for exit and survival. The past several years has witnessed many important advances in our understanding of the genetic/cellular damage produced by exposure to Cr(VI). Further information is needed regarding the potential involvement of oxygen radicals in Cr genotoxicity, the specific DNA repair pathways activated by Cr and the complex signaling mechanisms involved in the cellular response to Cr(VI). These pertinent issues must be considered in relation to the potential role that each plays in the induction of human respiratory tract cancer by particulate Cr(VI) compounds.","Complexities of chromium carcinogenesis: role of cellular response, repair and recovery mechanisms Abs: Certain hexavalent chromium (Cr(VI))-containing compounds are recognized occupational human lung carcinogens and may pose an environmental health risk. The carcinogenicity of Cr(VI) is targeted to particulate forms of moderate to low solubility. Soluble Cr(VI) oxyanions in the immediate cellular microenvironment traverse the cell membrane by non-specific anionic transporters. Cr(VI) is reductively metabolized within cells by agents including ascorbic acid (Asc), glutathione (GSH) and cysteine (Cys). During Cr(VI) reduction, a diverse range of genetic lesions are generated including Cr-DNA binary (mono) adducts, Cr-DNA ternary adducts, DNA protein crosslinks (DPCs), bi-functional (DNA interstrand crosslinks (ICLs)) adducts, single-strand breaks (SSBs) and oxidized bases. Some forms of Cr damage, such as ICLs, present physical barriers to DNA replication/transcription and, thus, likely promote a terminal cell fate such as apoptosis or terminal growth arrest. Other lesions, such as ternary DNA adducts, are potentially pre-mutagenic. Cr(VI) exposure elicits a classical DNA damage response within cells including activation of the p53 signaling pathway and cell cycle arrest or apoptosis. Moreover, Cr(VI) also induces the ATM-dependent DNA damage response pathway which is paradoxically required for both apoptosis and survival after Cr(VI) insult. In yeast, moderately cytotoxic concentrations of Cr(VI) result in an initial G1 arrest and delayed S phase progression, whereas less toxic levels of Cr(VI) induce G2 arrest, which requires homologous recombination for exit and survival. The past several years has witnessed many important advances in our understanding of the genetic/cellular damage produced by exposure to Cr(VI). Further information is needed regarding the potential involvement of oxygen radicals in Cr genotoxicity, the specific DNA repair pathways activated by Cr and the complex signaling mechanisms involved in the cellular response to Cr(VI). These pertinent issues must be considered in relation to the potential role that each plays in the induction of human respiratory tract cancer by particulate Cr(VI) compounds."
1232002,Tang et al. 2003,Sorption of Cr(VI) and Cu(II) in aqueous solution by ethylenediamine modified rice hull,"The sorption characteristics of Cr(VI) and Cu(II) by ethylenediamine modified rice hull from single and binary metal ion solutions were evaluated under various experimental conditions. Optimal Cr(VI) and Cu(II) removal from single metal ion solutions occurred at pH 2.0 and 5.5, respectively. Simultaneous removal of Cr(VI) and Cu(II) occurred at pH greater than 3.0. The sorption kinetics of Cr(VI) and Cu(II) from single and binary metal ion solutions were studied with reference to metal concentration, agitation rate and particle size. Sorption of Cr(VI) was more rapid than Cu(II). The kinetics of metal ion sorption fitted a pseudo-second order expression. The variation in the initial uptake rates was very small at an agitation rate beyond 150 rpm and sorption was generally independent of particle size. Equilibrium sorption data could be fitted into the Langmuir isotherm equation. Maximum sorption capacities of ethylenediamine modified rice hull for Cr(VI) at pH 2 and Cu(II) at pH 4 in single metal solutions were 0.45 and 0.06 mmol g(-1), respectively. This corresponds to an enhancement factor of 2.6 and 3 fold for Cr(VI) and Cu(II), respectively, compared to natural rice hull. A synergistic effect was observed for sorption of these ions in binary metal solutions.","Sorption of Cr(VI) and Cu(II) in aqueous solution by ethylenediamine modified rice hull Abs: The sorption characteristics of Cr(VI) and Cu(II) by ethylenediamine modified rice hull from single and binary metal ion solutions were evaluated under various experimental conditions. Optimal Cr(VI) and Cu(II) removal from single metal ion solutions occurred at pH 2.0 and 5.5, respectively. Simultaneous removal of Cr(VI) and Cu(II) occurred at pH greater than 3.0. The sorption kinetics of Cr(VI) and Cu(II) from single and binary metal ion solutions were studied with reference to metal concentration, agitation rate and particle size. Sorption of Cr(VI) was more rapid than Cu(II). The kinetics of metal ion sorption fitted a pseudo-second order expression. The variation in the initial uptake rates was very small at an agitation rate beyond 150 rpm and sorption was generally independent of particle size. Equilibrium sorption data could be fitted into the Langmuir isotherm equation. Maximum sorption capacities of ethylenediamine modified rice hull for Cr(VI) at pH 2 and Cu(II) at pH 4 in single metal solutions were 0.45 and 0.06 mmol g(-1), respectively. This corresponds to an enhancement factor of 2.6 and 3 fold for Cr(VI) and Cu(II), respectively, compared to natural rice hull. A synergistic effect was observed for sorption of these ions in binary metal solutions."
1232001,Hu et al. 2003,Immobilization of chromium(VI) with debris of aquatic plants,,Immobilization of chromium(VI) with debris of aquatic plants Abs: 
1231999,Tzou et al. 2003,Light-catalyzed chromium(VI) reduction by organic compounds and soil minerals,"Detoxification of Cr(VI) through reduction has been considered an effective method for reclaiming Cr-contaminated soil, sediment, and waste water. Organic matter is widely distributed in soil and aquatic systems; however, low Cr(VI) reduction rates inhibit the adoption of Cr reduction technologies by industry. Scientists have been aware of Cr(VI) reduction catalyzed by soil minerals; however, most of the studies focused on using semiconductors as catalysts with UV irradiation to accelerate the redox reactions. The objective of this study was to evaluate the rates of Cr(VI) reduction by fluorescence light in the presence of organic materials with or without specific soil minerals. Experimental results showed that dissolved organic compounds reduced Cr(VI) slowly under laboratory light; however, Cr(VI) reduction was greatly enhanced when growth chamber light was applied. Low photon flux (i.e., laboratory light) only enhanced Cr(VI) reduction by organics when Fe(III) was also present, because the Fe(II)-Fe(III) redox couple accelerated electron transfer and decreased electrostatic repulsion between reactants. Laboratory light was required to initiate Cr(VI) reduction catalyzed by TiO2; nonetheless, light-catalyzed Cr(VI) reduction by smectite and ferrihydrite could occur only when greater light energy was provided with a growth chamber light. Our results suggest a potential pathway for Cr(VI) reduction using naturally occurring organic compounds and colloids in acidic water systems or in surface soils when light is available.","Light-catalyzed chromium(VI) reduction by organic compounds and soil minerals Abs: Detoxification of Cr(VI) through reduction has been considered an effective method for reclaiming Cr-contaminated soil, sediment, and waste water. Organic matter is widely distributed in soil and aquatic systems; however, low Cr(VI) reduction rates inhibit the adoption of Cr reduction technologies by industry. Scientists have been aware of Cr(VI) reduction catalyzed by soil minerals; however, most of the studies focused on using semiconductors as catalysts with UV irradiation to accelerate the redox reactions. The objective of this study was to evaluate the rates of Cr(VI) reduction by fluorescence light in the presence of organic materials with or without specific soil minerals. Experimental results showed that dissolved organic compounds reduced Cr(VI) slowly under laboratory light; however, Cr(VI) reduction was greatly enhanced when growth chamber light was applied. Low photon flux (i.e., laboratory light) only enhanced Cr(VI) reduction by organics when Fe(III) was also present, because the Fe(II)-Fe(III) redox couple accelerated electron transfer and decreased electrostatic repulsion between reactants. Laboratory light was required to initiate Cr(VI) reduction catalyzed by TiO2; nonetheless, light-catalyzed Cr(VI) reduction by smectite and ferrihydrite could occur only when greater light energy was provided with a growth chamber light. Our results suggest a potential pathway for Cr(VI) reduction using naturally occurring organic compounds and colloids in acidic water systems or in surface soils when light is available."
1231998,NTP 2004,Chromium hexavalent compounds,,Chromium hexavalent compounds Abs: 
1231997,Melwanki and  Seetharamappa 2003,Spectrophotometric studies on the investigation of chromium in environmental samples,Isothipendyl hydrochloride is proposed as a sensitive and selective reagent for the rapid spectrophotometric determination of chromium(VI). The reagent instantaneously gives a red coloured species on reaction with chromium(VI) in phosphoric acid medium which exhibits maximum absorbance at 510 nm with Sandell's sensitivity of 2.28 ng cm(-2). Beer's law is valid over the concentraction range of 0.1-1.9 mg/l with an optimum concentration range of 0.2-1.7 mg/l. The method has been successfully applied to the analysis of chromium in environmental samples.,Spectrophotometric studies on the investigation of chromium in environmental samples Abs: Isothipendyl hydrochloride is proposed as a sensitive and selective reagent for the rapid spectrophotometric determination of chromium(VI). The reagent instantaneously gives a red coloured species on reaction with chromium(VI) in phosphoric acid medium which exhibits maximum absorbance at 510 nm with Sandell's sensitivity of 2.28 ng cm(-2). Beer's law is valid over the concentraction range of 0.1-1.9 mg/l with an optimum concentration range of 0.2-1.7 mg/l. The method has been successfully applied to the analysis of chromium in environmental samples.
1231996,Mise and  Rajamanya 2003,Adsorption studies of chromium (VI) on activated carbon derived from Sorghum vulgare (dried stem of Jowar),"The present work deals with the adsorption studies of chromium (VI) on activated carbon derived from Sorghum vulgare (dried stem of Jowar). The activated carbons were prepared by physical and chemical activation using H2SO4, H3PO4 activating agents of different imprignation Ratio (I.R.). The effect of adsorption of Cr (VI) on pH, particle size concentration, contact time and dosage have been studied. Removal of chromium (VI) attained in equilibrium maxium of 50 minutes and slightly decreases with increasing I.R. Adsorption obeys first order rate equation and Webber and Morris equation for pore diffusion. Adsorption increases with decrease in pH, is maximum at pH 2. Increase in imprignation ratio also increases surface area of Sorghum vulgare carbons.","Adsorption studies of chromium (VI) on activated carbon derived from Sorghum vulgare (dried stem of Jowar) Abs: The present work deals with the adsorption studies of chromium (VI) on activated carbon derived from Sorghum vulgare (dried stem of Jowar). The activated carbons were prepared by physical and chemical activation using H2SO4, H3PO4 activating agents of different imprignation Ratio (I.R.). The effect of adsorption of Cr (VI) on pH, particle size concentration, contact time and dosage have been studied. Removal of chromium (VI) attained in equilibrium maxium of 50 minutes and slightly decreases with increasing I.R. Adsorption obeys first order rate equation and Webber and Morris equation for pore diffusion. Adsorption increases with decrease in pH, is maximum at pH 2. Increase in imprignation ratio also increases surface area of Sorghum vulgare carbons."
1231994,Roldán et al. 2004,Kinetics and mechanism of the reduction of CrVI and CrV by D-lactobionic acid,"The oxidation of D-lactobionic acid by Cr(VI) yields the 2-ketoaldobionic acid and Cr(3+) as final products when a 20-times or higher excess of the aldobionic acid over Cr(VI) is used. The redox reaction takes place through a complex multistep mechanism, which involves the formation of intermediate Cr(IV) and Cr(V) species. Cr(IV) reacts with lactobionic acid much faster than Cr(V) and Cr(VI) do, and cannot be directly detected. However, the formation of CrO(2)(2+), observed by the first time for an acid saccharide/Cr(VI) system, provides indirect evidence for the intermediacy of Cr(IV) in the reaction path. Cr(VI) and the intermediate Cr(V) react with lactobionic acid at comparable rates, being the complete rate laws for the Cr(VI) and Cr(V) consumption expressed by: -d[Cr(VI)]/dt=[k(I)+k(II)[H(+)]][lactobionicacid][Cr(VI)], where k(I)=(4.1+/-0.1) x 10(-3) M(-1) s(-1) and k(II)=(2.1+/-0.1) x 10(-2) M(-2) s(-1); and -d[Cr(V)]/dt=[k(III)[H(+)]+(k(IV)+k(V)[H(+)])[lactobionicacid]] [Cr(V)], where k(III)=(1.8+/-0.1) x 10(-3) M(-1) s(-1), k(IV)=(1.1+/-0.1) x 10(-2) M(-1) s(-1) and k(V)=(1.0+/-0.1) x 10(-2) M(-2) s(-1), at 33 degrees C. The Electron Paramagnetic Resonance (EPR) spectra show that five-co-ordinate oxo-Cr(V) bischelates are formed at pH 1-5 with the aldobionic acid bound to Cr(V) through the alpha-hydroxyacid group.","Kinetics and mechanism of the reduction of CrVI and CrV by D-lactobionic acid Abs: The oxidation of D-lactobionic acid by Cr(VI) yields the 2-ketoaldobionic acid and Cr(3+) as final products when a 20-times or higher excess of the aldobionic acid over Cr(VI) is used. The redox reaction takes place through a complex multistep mechanism, which involves the formation of intermediate Cr(IV) and Cr(V) species. Cr(IV) reacts with lactobionic acid much faster than Cr(V) and Cr(VI) do, and cannot be directly detected. However, the formation of CrO(2)(2+), observed by the first time for an acid saccharide/Cr(VI) system, provides indirect evidence for the intermediacy of Cr(IV) in the reaction path. Cr(VI) and the intermediate Cr(V) react with lactobionic acid at comparable rates, being the complete rate laws for the Cr(VI) and Cr(V) consumption expressed by: -d[Cr(VI)]/dt=[k(I)+k(II)[H(+)]][lactobionicacid][Cr(VI)], where k(I)=(4.1+/-0.1) x 10(-3) M(-1) s(-1) and k(II)=(2.1+/-0.1) x 10(-2) M(-2) s(-1); and -d[Cr(V)]/dt=[k(III)[H(+)]+(k(IV)+k(V)[H(+)])[lactobionicacid]] [Cr(V)], where k(III)=(1.8+/-0.1) x 10(-3) M(-1) s(-1), k(IV)=(1.1+/-0.1) x 10(-2) M(-1) s(-1) and k(V)=(1.0+/-0.1) x 10(-2) M(-2) s(-1), at 33 degrees C. The Electron Paramagnetic Resonance (EPR) spectra show that five-co-ordinate oxo-Cr(V) bischelates are formed at pH 1-5 with the aldobionic acid bound to Cr(V) through the alpha-hydroxyacid group."
1231993,Wise et al. 2004,Telomerase-mediated lifespan extension of human bronchial cells does not affect hexavalent chromium-induced cytotoxicity or genotoxicity,"Hexavalent chromium (Cr(VI)) is a metal of increasing public health concern, as exposure to it is widespread and it is a well-established cause of human bronchial carcinomas and fibrosarcomas. The water-insoluble Cr(VI) salts are potent carcinogens compared to the water soluble salts; yet the genotoxic mechanisms of both may be mediated by soluble Cr(VI) ions. Currently, these mechanisms are poorly understood. Emerging evidence suggests that initial cell culture models used to study the general toxicity of Cr(VI) may be suboptimal for investigating mechanisms specific to human bronchial cells. Accordingly, we have developed a new model system of human bronchial cells by introducing hTERT, the catalytic subunit of human telomerase, into primary human bronchial fibroblasts (PHBF). We have isolated a stable, clonally derived cell line, WHTBF-6, that demonstrate reconstitution of telomerase activity and maintenance of telomere lengths with increasing culture age. WHTBF-6 has been characterized as having an extended in vitro lifespan, a normal growth rate, a normal diploid karyotype that is maintained over time, and exhibits serum-dependent contact-inhibited anchorage-dependent growth. Moreover, we find that both particulate and soluble hexavalent chromium induce a pattern and degree of cytotoxicity and clastogenicity in WHTBF-6 that is similar to the parental PHBF cells. Because telomerase does not compromise growth or the response to Cr(VI), our results indicate that this is an excellent system for studying the mechanisms of Cr(VI) and potentially other carcinogens implicated in the development of lung cancer.","Telomerase-mediated lifespan extension of human bronchial cells does not affect hexavalent chromium-induced cytotoxicity or genotoxicity Abs: Hexavalent chromium (Cr(VI)) is a metal of increasing public health concern, as exposure to it is widespread and it is a well-established cause of human bronchial carcinomas and fibrosarcomas. The water-insoluble Cr(VI) salts are potent carcinogens compared to the water soluble salts; yet the genotoxic mechanisms of both may be mediated by soluble Cr(VI) ions. Currently, these mechanisms are poorly understood. Emerging evidence suggests that initial cell culture models used to study the general toxicity of Cr(VI) may be suboptimal for investigating mechanisms specific to human bronchial cells. Accordingly, we have developed a new model system of human bronchial cells by introducing hTERT, the catalytic subunit of human telomerase, into primary human bronchial fibroblasts (PHBF). We have isolated a stable, clonally derived cell line, WHTBF-6, that demonstrate reconstitution of telomerase activity and maintenance of telomere lengths with increasing culture age. WHTBF-6 has been characterized as having an extended in vitro lifespan, a normal growth rate, a normal diploid karyotype that is maintained over time, and exhibits serum-dependent contact-inhibited anchorage-dependent growth. Moreover, we find that both particulate and soluble hexavalent chromium induce a pattern and degree of cytotoxicity and clastogenicity in WHTBF-6 that is similar to the parental PHBF cells. Because telomerase does not compromise growth or the response to Cr(VI), our results indicate that this is an excellent system for studying the mechanisms of Cr(VI) and potentially other carcinogens implicated in the development of lung cancer."
1231992,Wang et al. 2004,Role of reactive oxygen species and Cr(VI) in Ras-mediated signal transduction,"Previous studies have shown that a constitutively active isoform of Ras is able to produce superoxide radical (O2(-)). The present study investigate the mechanisms by which O2(-) radical mediates signals from Ras protein to the nucleus, leading to cellular responses such as apoptosis in Cr(VI)-stimulated cells. Two human prostate tumor cell lines, Ras(+), which overexpresses Ras, and Ras(-), which has a normal Ras level, were utilized. Compared to Ras(-) cells, Ras(+) cells exhibited higher susceptibility to apoptosis induced by Cr(VI). Catalase, sodium formate, and deferoxamine inhibited Cr(VI)-induced apoptosis. Similar differences were observed in both cellular DNA damage and the activation of p53 protein. The differences in Cr(VI)-induced cell responses in Ras(+) and Ras(-) cells were due to differences in the generation of free radicals between these two cells. ESR spin trapping measurements showed that Ras(+) cells generated more hydroxyl radical ((.)OH), O2(-) radical, and Cr(V) than Ras(-) cells following Cr(VI) stimulation. The generation of the reactive oxygen species (ROS) can be abolished by the addition of superoxide dismutase (SOD) or if the experiment were carried out in an argon atmosphere. Catalase inhibited spin adduct signals but was much less potent than SOD. The mechanism of ROS generation in Cr(VI)-stimulated Ras(+) cells involves the reduction of molecular oxygen to O2(-) radical by a flavoenzyme-containing NADPH oxidase complex as shown by oxygen consumption and diphenylene iodonium (DPI) inhibition. Results shown above support the following conclusions: (a) Ras protein mediates O2(-) radical generation through reduction of molecular oxygen by NADPH oxidase in Cr(VI)-stimulated cells. (b) The O2(-) radical and Cr(VI) produce other reactive species, including H2O2, OH radical, and Cr(V) through O2(-) dismutation and Haber-Weiss type of reactions. (c) Among these reactive species, (.)OH radical is responsible for the further transduction of signals from Ras to the nucleus, leading to various cell responses.","Role of reactive oxygen species and Cr(VI) in Ras-mediated signal transduction Abs: Previous studies have shown that a constitutively active isoform of Ras is able to produce superoxide radical (O2(-)). The present study investigate the mechanisms by which O2(-) radical mediates signals from Ras protein to the nucleus, leading to cellular responses such as apoptosis in Cr(VI)-stimulated cells. Two human prostate tumor cell lines, Ras(+), which overexpresses Ras, and Ras(-), which has a normal Ras level, were utilized. Compared to Ras(-) cells, Ras(+) cells exhibited higher susceptibility to apoptosis induced by Cr(VI). Catalase, sodium formate, and deferoxamine inhibited Cr(VI)-induced apoptosis. Similar differences were observed in both cellular DNA damage and the activation of p53 protein. The differences in Cr(VI)-induced cell responses in Ras(+) and Ras(-) cells were due to differences in the generation of free radicals between these two cells. ESR spin trapping measurements showed that Ras(+) cells generated more hydroxyl radical ((.)OH), O2(-) radical, and Cr(V) than Ras(-) cells following Cr(VI) stimulation. The generation of the reactive oxygen species (ROS) can be abolished by the addition of superoxide dismutase (SOD) or if the experiment were carried out in an argon atmosphere. Catalase inhibited spin adduct signals but was much less potent than SOD. The mechanism of ROS generation in Cr(VI)-stimulated Ras(+) cells involves the reduction of molecular oxygen to O2(-) radical by a flavoenzyme-containing NADPH oxidase complex as shown by oxygen consumption and diphenylene iodonium (DPI) inhibition. Results shown above support the following conclusions: (a) Ras protein mediates O2(-) radical generation through reduction of molecular oxygen by NADPH oxidase in Cr(VI)-stimulated cells. (b) The O2(-) radical and Cr(VI) produce other reactive species, including H2O2, OH radical, and Cr(V) through O2(-) dismutation and Haber-Weiss type of reactions. (c) Among these reactive species, (.)OH radical is responsible for the further transduction of signals from Ras to the nucleus, leading to various cell responses."
1231991,Wang et al. 2004,NF-kappaB prevents cells from undergoing Cr(VI)-induced apoptosis,"The transcription factor NF-kappaB has been reported to prevent cells from undergoing apoptosis as well as promote cell apoptosis. To investigate the role of NF-kappaB in Cr(VI)-induced apoptosis, two cell lines were developed from human bronchial epithelial BEAS-2B cells: IKK cells, which were stably transfected with IkappaBalpha expression vector, that have normal NF-kappaB activity, and KM cells, which were stably transfected with mutated IkappaBalpha kinase expression vector, that exhibit very little NF-kappaB activity. With Cr(VI) stimulation, KM cells, but not IKK cells, exhibited substantial cell death. Cell morphological and TUNEL analyses indicated that the KM cells showed apoptotic features. These results suggest that NF-kappaB activation is required to prevent the cells from undergoing Cr(VI)-induced apoptosis.","NF-kappaB prevents cells from undergoing Cr(VI)-induced apoptosis Abs: The transcription factor NF-kappaB has been reported to prevent cells from undergoing apoptosis as well as promote cell apoptosis. To investigate the role of NF-kappaB in Cr(VI)-induced apoptosis, two cell lines were developed from human bronchial epithelial BEAS-2B cells: IKK cells, which were stably transfected with IkappaBalpha expression vector, that have normal NF-kappaB activity, and KM cells, which were stably transfected with mutated IkappaBalpha kinase expression vector, that exhibit very little NF-kappaB activity. With Cr(VI) stimulation, KM cells, but not IKK cells, exhibited substantial cell death. Cell morphological and TUNEL analyses indicated that the KM cells showed apoptotic features. These results suggest that NF-kappaB activation is required to prevent the cells from undergoing Cr(VI)-induced apoptosis."
1231990,Ceryak et al. 2004,Induction of pro-apoptotic and cell cycle-inhibiting genes in chromium (VI)-treated human lung fibroblasts: Lack of effect of ERK,"Cell proliferation and apoptosis are controlled by tightly orchestrated signaling pathways that culminate in transcriptional activation/repression of multiple proteins. Dysregulation of cell cycle and/or apoptosis control may lead to genomic instability, neoplastic transformation and tumor progression. Under certain conditions, some hexavalent chromium [Cr(VI)] compounds are toxic and carcinogenic in the human respiratory tract, and we have shown that they induce apoptosis and/or cell cycle arrest in a p53-dependent fashion. There is increasing evidence linking extracellular signal-regulated kinase (ERK) activation with the DNA damage response, by both p53-dependent and -independent mechanisms. Here, the aim was to study the effect of Cr(VI) transcriptional regulation of key cell cycle inhibitors and pro- and anti-apoptotic proteins, as well as the role of ERK activation in the Cr(VI) genotoxic response. Diploid human lung fibroblasts were incubated with 3-9 uM Na2CrO4, and RNA was isolated at 4, 8, and 24 h, as well as 24 h after Cr(VI) exposure was terminated (recovery). mRNA expression was quantitated by RNase protection assay with a 32P-labeled multi-transcript probe containing gene sequences for the cdk inhibitors, p21waf1/cip1, p27kip1, p16INK4a, p15INK4b; the pro-apoptotic proteins bcl-XS and bax; the anti-apoptotic proteins bcl-W, bcl-XL, and bcl2, GADD45, and cyclin A. In general, bcl-W and bcl-XL expression were both downregulated after Cr exposure, to around 50% at 24 h, which was more pronounced after the recovery period. At Cr(VI) concentrations < or = 6 uM, bcl2 expression was upregulated. Of particular interest is that bax expression was reduced, in a dose and time-dependent fashion, however that of bcl-XS was elevated by nearly 3-fold after 8 h, and declined to control levels at the end of the recovery period. Expression of GADD45 and p21 were both upregulated by 2-fold at 8 h, but declined to control levels during recovery. Neither the expression of p27 nor that of p16 were apparently affected by Cr(VI) exposure, however the expression of p15 was markedly increased after exposure to all concentrations of Cr(VI). Finally, the expression of cyclin A was decreased after 24 h Cr(VI) exposure. Cr(VI) induced a transient burst of ERK activity (2-6-fold over control) around 0.5-3 h after exposure. However, inhibition of ERK activation with PD98059 had no effect on the Cr-induced alterations in gene expression. Moreover, Cr(VI)-induced clonogenic lethality, as assessed after 24 h exposure to 1 and 2 uM Cr(VI), was also not affected by ERK inhibition. These data suggest that both p53-dependent and -independent apoptotic and growth-inhibitory pathways are markedly affected by Cr(VI) exposure. However, the ability of Cr(VI) to affect key apoptotic and growth arresting genes, and thus clonogenic lethality, appears to be independent of ERK. Continued investigation into the cellular and molecular mechanisms of Cr(VI)-induced cell cycle and apoptosis control should further the understanding of Cr(VI)-associated carcinogenesis.","Induction of pro-apoptotic and cell cycle-inhibiting genes in chromium (VI)-treated human lung fibroblasts: Lack of effect of ERK Abs: Cell proliferation and apoptosis are controlled by tightly orchestrated signaling pathways that culminate in transcriptional activation/repression of multiple proteins. Dysregulation of cell cycle and/or apoptosis control may lead to genomic instability, neoplastic transformation and tumor progression. Under certain conditions, some hexavalent chromium [Cr(VI)] compounds are toxic and carcinogenic in the human respiratory tract, and we have shown that they induce apoptosis and/or cell cycle arrest in a p53-dependent fashion. There is increasing evidence linking extracellular signal-regulated kinase (ERK) activation with the DNA damage response, by both p53-dependent and -independent mechanisms. Here, the aim was to study the effect of Cr(VI) transcriptional regulation of key cell cycle inhibitors and pro- and anti-apoptotic proteins, as well as the role of ERK activation in the Cr(VI) genotoxic response. Diploid human lung fibroblasts were incubated with 3-9 uM Na2CrO4, and RNA was isolated at 4, 8, and 24 h, as well as 24 h after Cr(VI) exposure was terminated (recovery). mRNA expression was quantitated by RNase protection assay with a 32P-labeled multi-transcript probe containing gene sequences for the cdk inhibitors, p21waf1/cip1, p27kip1, p16INK4a, p15INK4b; the pro-apoptotic proteins bcl-XS and bax; the anti-apoptotic proteins bcl-W, bcl-XL, and bcl2, GADD45, and cyclin A. In general, bcl-W and bcl-XL expression were both downregulated after Cr exposure, to around 50% at 24 h, which was more pronounced after the recovery period. At Cr(VI) concentrations < or = 6 uM, bcl2 expression was upregulated. Of particular interest is that bax expression was reduced, in a dose and time-dependent fashion, however that of bcl-XS was elevated by nearly 3-fold after 8 h, and declined to control levels at the end of the recovery period. Expression of GADD45 and p21 were both upregulated by 2-fold at 8 h, but declined to control levels during recovery. Neither the expression of p27 nor that of p16 were apparently affected by Cr(VI) exposure, however the expression of p15 was markedly increased after exposure to all concentrations of Cr(VI). Finally, the expression of cyclin A was decreased after 24 h Cr(VI) exposure. Cr(VI) induced a transient burst of ERK activity (2-6-fold over control) around 0.5-3 h after exposure. However, inhibition of ERK activation with PD98059 had no effect on the Cr-induced alterations in gene expression. Moreover, Cr(VI)-induced clonogenic lethality, as assessed after 24 h exposure to 1 and 2 uM Cr(VI), was also not affected by ERK inhibition. These data suggest that both p53-dependent and -independent apoptotic and growth-inhibitory pathways are markedly affected by Cr(VI) exposure. However, the ability of Cr(VI) to affect key apoptotic and growth arresting genes, and thus clonogenic lethality, appears to be independent of ERK. Continued investigation into the cellular and molecular mechanisms of Cr(VI)-induced cell cycle and apoptosis control should further the understanding of Cr(VI)-associated carcinogenesis."
1231989,Martínez et al. 2004,Removal of chromium hexavalent from rinsing chromating waters electrochemical reduction in a laboratory pilot plant,"In this work, experiments in a 16 L operating volume laboratory pilot plant with ring iron rotary electrodes were performed, obtaining an overall kinetic equation rate of hexavalent chromium reduction concentration and current density-dependent. Other scale-up criteria such as Reynolds' number were also evaluated to ensure a completely stirred reactor at low energy expenditure. A dimensionless N(E) is a relationship between liquid properties and the electric charge supplied to the system. The number, which depends on the rotation iron ring electrode speed number and the current density, is proposed to be used as scale-up criterion. It was found that at N(Re) = 42,179 (130 rpm rotation electrodes rate) and at N(E) = 9.8 x 10(5) (current density of 113 A/m2), complete mixing was reached at minimum energy spent and the process becomes more efficient. In addition, it was found that the higher the current density, the less treatment time and less energy spent on agitation. After the electrochemical treatment the Cr(VI) concentration in the rinsing wastewater was less than 0.5 mg/L.","Removal of chromium hexavalent from rinsing chromating waters electrochemical reduction in a laboratory pilot plant Abs: In this work, experiments in a 16 L operating volume laboratory pilot plant with ring iron rotary electrodes were performed, obtaining an overall kinetic equation rate of hexavalent chromium reduction concentration and current density-dependent. Other scale-up criteria such as Reynolds' number were also evaluated to ensure a completely stirred reactor at low energy expenditure. A dimensionless N(E) is a relationship between liquid properties and the electric charge supplied to the system. The number, which depends on the rotation iron ring electrode speed number and the current density, is proposed to be used as scale-up criterion. It was found that at N(Re) = 42,179 (130 rpm rotation electrodes rate) and at N(E) = 9.8 x 10(5) (current density of 113 A/m2), complete mixing was reached at minimum energy spent and the process becomes more efficient. In addition, it was found that the higher the current density, the less treatment time and less energy spent on agitation. After the electrochemical treatment the Cr(VI) concentration in the rinsing wastewater was less than 0.5 mg/L."
1231988,Camargo et al. 2004,"Hexavalent chromium reduction by an actinomycete, arthrobacter crystallopoietes ES 32","Environmental contamination by hexavalent chromium, Cr(VI), presents a serious public health problem. This study assessed the reduction of Cr(VI) by intact cells and a cell-free extract (CFE) of an actinomycete, Arthrobacter crystallopoietes (strain ES 32), isolated from soil contaminated with dichromate. Both intact cells and CFE of A. crystallopoietes, displayed substantial reduction of Cr(VI). Intact cells reduced about 90% of the Cr(VI) added within 12 h and Cr(VI) was almost completely reduced after 24 h. The KM and Vmax of Cr(VI) bioreduction by intact cells were 2.61 microM and 0.0142 micromol/min/mg protein, respectively. Cell-free chromate reductase of the A. crystallopoietes (ES 32) reduced hexavalent chromium at a KM of 1.78 microM and a Vmax of 0.096 micromol/min/mg protein. The rate constant (k) of chromate reduction was inversely related to Cr(VI) concentration and the half-life (t1/2) of Cr(VI) reduction increased with increasing concentration. A. crystallopoietes produced a periplasmic chromate reductase that was stimulated by NADH. Results indicate that A. crystallopoietes ES 32 can be used to detoxify Cr(VI) in polluted sites, particularly in stressed environments.","Hexavalent chromium reduction by an actinomycete, arthrobacter crystallopoietes ES 32 Abs: Environmental contamination by hexavalent chromium, Cr(VI), presents a serious public health problem. This study assessed the reduction of Cr(VI) by intact cells and a cell-free extract (CFE) of an actinomycete, Arthrobacter crystallopoietes (strain ES 32), isolated from soil contaminated with dichromate. Both intact cells and CFE of A. crystallopoietes, displayed substantial reduction of Cr(VI). Intact cells reduced about 90% of the Cr(VI) added within 12 h and Cr(VI) was almost completely reduced after 24 h. The KM and Vmax of Cr(VI) bioreduction by intact cells were 2.61 microM and 0.0142 micromol/min/mg protein, respectively. Cell-free chromate reductase of the A. crystallopoietes (ES 32) reduced hexavalent chromium at a KM of 1.78 microM and a Vmax of 0.096 micromol/min/mg protein. The rate constant (k) of chromate reduction was inversely related to Cr(VI) concentration and the half-life (t1/2) of Cr(VI) reduction increased with increasing concentration. A. crystallopoietes produced a periplasmic chromate reductase that was stimulated by NADH. Results indicate that A. crystallopoietes ES 32 can be used to detoxify Cr(VI) in polluted sites, particularly in stressed environments."
1231987,Nurminen 2004,On the carcinogenicity risk assessment of chromium compounds,,On the carcinogenicity risk assessment of chromium compounds Abs: 
1231986,Pamukcu et al. 2004,Enhanced reduction of Cr(VI) by direct electric current in a contaminated clay,"The probable relation between diffuse double-layer processes and redox reactions that enhance degradation or conversion of contaminants under an applied electric field were examined in a clay medium. Kaolinite clay, precontaminated with hexavalent chromium, was the test soil medium. Analyte, containing ferrous iron, was transported through the kaolinite clay using direct electric current. The Cr(VI) reduction to Cr(III) was followed by measuring the soil redox potential and pH at discrete locations in the clay bed. The post-test distribution of Cr showed significantly more Cr(III) than Cr(VI) at low to slightly acidic pH distribution (2 &lt; pH &lt; 6) in clay. The stoichiometric analyses of measured chromium and iron species concentrations versus the measured redox potentials were compared to Nernst equation predictions of an equivalent aqueous system. An average of +0.37 V shift was measured from the linear Nernstian prediction of cell potential. The applied electric field appeared to provide additional &quot;cathodic current&quot; to drive forth the redox reactions. The redox potential shift was explained by possible overpotential development at the clay-water interfaces due to double-layer polarization under the applied field.","Enhanced reduction of Cr(VI) by direct electric current in a contaminated clay Abs: The probable relation between diffuse double-layer processes and redox reactions that enhance degradation or conversion of contaminants under an applied electric field were examined in a clay medium. Kaolinite clay, precontaminated with hexavalent chromium, was the test soil medium. Analyte, containing ferrous iron, was transported through the kaolinite clay using direct electric current. The Cr(VI) reduction to Cr(III) was followed by measuring the soil redox potential and pH at discrete locations in the clay bed. The post-test distribution of Cr showed significantly more Cr(III) than Cr(VI) at low to slightly acidic pH distribution (2 &lt; pH &lt; 6) in clay. The stoichiometric analyses of measured chromium and iron species concentrations versus the measured redox potentials were compared to Nernst equation predictions of an equivalent aqueous system. An average of +0.37 V shift was measured from the linear Nernstian prediction of cell potential. The applied electric field appeared to provide additional &quot;cathodic current&quot; to drive forth the redox reactions. The redox potential shift was explained by possible overpotential development at the clay-water interfaces due to double-layer polarization under the applied field."
1231984,Battaglia-Brunet et al. 2004,Chromate reduction at low sulphate concentration in hydrogen-fed bioreactors,"Aimed at developing a bioremediation process to treat Cr(VI)-bearing water at low sulphate concentration in order to reduce excess sulphide production, the highly toxic, mutagenic, and soluble Cr(VI) was reduced to the less toxic and insoluble Cr(III) in 2-litre fixed-bed reactors inoculated with the sulphate-reducing bacterium (SRB) Desulfomicrobium norvegicum, capable of performing direct enzymatic Cr(VI) reduction. H2 was used as the electron source. The fixed-films were developed on three different supports: a PVC cross-flow material, a pozzolana, and a ceramic granulate. The phased experiments began with a progressive increase of the Cr(VI) concentration in the feed to the column reactors, followed by a progressive decrease of the sulphate concentration. Inhibition by Cr(VI) was less pronounced with pozzolana than with the other supports; when the pozzolana column was fed with a medium containing 100 mg l(-1) Cr(VI) and only 250 mg l(-1) sulphate, the lowest residence time that could be applied for complete Cr(VI) reduction was 16 h. The molar ratio between the sulphate and Cr(VI) reduction rates was decreased down to 1.5, suggesting that indirect reaction with HS was not the sole mechanism of Cr(VI) reduction.","Chromate reduction at low sulphate concentration in hydrogen-fed bioreactors Abs: Aimed at developing a bioremediation process to treat Cr(VI)-bearing water at low sulphate concentration in order to reduce excess sulphide production, the highly toxic, mutagenic, and soluble Cr(VI) was reduced to the less toxic and insoluble Cr(III) in 2-litre fixed-bed reactors inoculated with the sulphate-reducing bacterium (SRB) Desulfomicrobium norvegicum, capable of performing direct enzymatic Cr(VI) reduction. H2 was used as the electron source. The fixed-films were developed on three different supports: a PVC cross-flow material, a pozzolana, and a ceramic granulate. The phased experiments began with a progressive increase of the Cr(VI) concentration in the feed to the column reactors, followed by a progressive decrease of the sulphate concentration. Inhibition by Cr(VI) was less pronounced with pozzolana than with the other supports; when the pozzolana column was fed with a medium containing 100 mg l(-1) Cr(VI) and only 250 mg l(-1) sulphate, the lowest residence time that could be applied for complete Cr(VI) reduction was 16 h. The molar ratio between the sulphate and Cr(VI) reduction rates was decreased down to 1.5, suggesting that indirect reaction with HS was not the sole mechanism of Cr(VI) reduction."
1231983,Ramírez-Ramírez et al. 2004,Cr(VI) reduction in a chromate-resistant strain of Candida maltosa isolated from the leather industry,"A Cr(VI)-resistant yeast was isolated from tanning liquors from a leather factory in Leon, Guanajuato, Mexico. Based on morphological and physiological analyses and the D1/D2 domain sequence of the 26S rDNA, the yeast was identified as Candida maltosa. Resistance of the strain to high Cr(VI) concentrations and its ability to chemically reduce chromium was studied. When compared to the three laboratory yeasts Candida albicans, Saccharomyces cerevisiae and Yarrowia lipolytica, the C. maltosa strain was found to tolerate chromate concentrations as high as 100 micro g/ml. In addition to this phenotypic trait, the C. maltosa strain showed ability to reduce Cr(VI). Chromate reduction occurred both in intact cells (grown in culture medium or in soil containing chromate) as well as in cell-free extracts. NADH-dependent chromate reductase activity was found associated with soluble protein and, to a lesser extent, with the membrane fraction.","Cr(VI) reduction in a chromate-resistant strain of Candida maltosa isolated from the leather industry Abs: A Cr(VI)-resistant yeast was isolated from tanning liquors from a leather factory in Leon, Guanajuato, Mexico. Based on morphological and physiological analyses and the D1/D2 domain sequence of the 26S rDNA, the yeast was identified as Candida maltosa. Resistance of the strain to high Cr(VI) concentrations and its ability to chemically reduce chromium was studied. When compared to the three laboratory yeasts Candida albicans, Saccharomyces cerevisiae and Yarrowia lipolytica, the C. maltosa strain was found to tolerate chromate concentrations as high as 100 micro g/ml. In addition to this phenotypic trait, the C. maltosa strain showed ability to reduce Cr(VI). Chromate reduction occurred both in intact cells (grown in culture medium or in soil containing chromate) as well as in cell-free extracts. NADH-dependent chromate reductase activity was found associated with soluble protein and, to a lesser extent, with the membrane fraction."
1231982,Erdem and  Tümen 2004,A study on dissolution properties of the sludges from Cr(VI) reduction-precipitation processes,"In this article, dissolution characteristics of Cr(VI) reduction-precipitation sludges in the solutions containing mineral acids, organic complexing materials or both are examined. For this purpose, the effects of pH, concentration of complex forming agent and contact time on dissolution of metals from two different sludges obtained by using sodium sulphite and ferrous sulphate as reducing agents are studied. In addition, pollution potentials of the sludges are determined by applying the toxicity tests of TCLP, SPLP, USEPA-1979, and USEPA-19X0. It was found that pH, contact time, concentration and type of complex forming substances are effective parameters on dissolution of metals from the sludges. In mineral acid solutions at pH 3, especially in the presence of organic complexing substances, chromium leached out from hydroxide sludges exceeds the concentration limits of USEPA for hazardous wastes. The amounts of chromium dissolved in the citric and ascorbic acid solutions and the amount of iron dissolved in the EDTA solution were found to be higher than in the other test solutions. Also, TCLP test shows that chromium hydroxide sludge obtained from sulphite reduction precipitation process of Cr(VI) is a potential hazardous solid. According to the results of this study, considering the probable presence of complexing agents in the disposal sites, toxicity test methods should be modified.","A study on dissolution properties of the sludges from Cr(VI) reduction-precipitation processes Abs: In this article, dissolution characteristics of Cr(VI) reduction-precipitation sludges in the solutions containing mineral acids, organic complexing materials or both are examined. For this purpose, the effects of pH, concentration of complex forming agent and contact time on dissolution of metals from two different sludges obtained by using sodium sulphite and ferrous sulphate as reducing agents are studied. In addition, pollution potentials of the sludges are determined by applying the toxicity tests of TCLP, SPLP, USEPA-1979, and USEPA-19X0. It was found that pH, contact time, concentration and type of complex forming substances are effective parameters on dissolution of metals from the sludges. In mineral acid solutions at pH 3, especially in the presence of organic complexing substances, chromium leached out from hydroxide sludges exceeds the concentration limits of USEPA for hazardous wastes. The amounts of chromium dissolved in the citric and ascorbic acid solutions and the amount of iron dissolved in the EDTA solution were found to be higher than in the other test solutions. Also, TCLP test shows that chromium hydroxide sludge obtained from sulphite reduction precipitation process of Cr(VI) is a potential hazardous solid. According to the results of this study, considering the probable presence of complexing agents in the disposal sites, toxicity test methods should be modified."
1231980,Testa et al. 2004,Heterogeneous photocatalytic reduction of chromium(VI) over TiO2 particles in the presence of oxalate: involvement of Cr(V) species,"Cr(VI) photocatalytic reduction experiments over TiO2 particles under near UV irradiation in the presence of excess oxalate were performed at acid pH (2 and 3) and under air and N2 bubbling. Initial photonic efficiencies for Cr(VI) reduction are nearly the same under aerobic and anaerobic conditions, but show a significant increase at the lowest pH. At pH 2, the addition of oxalate facilitates Cr(VI) reduction, hindering the electron-shuttle mechanism taking place in pure water. The oxalate synergistic effect at pH 2 is lower than that previously found for EDTA and negligible at pH 3. Chromium(V) oxalate concentration profiles were obtained by EPR spectroscopy in the presence of excess oxalate at pH 1.5. Coordinated Cr(V) complexes [Cr(V)(O)(Ox)2]-, [Cr(V)(OH2)(Ox)2]-, and [Cr(V)(O)(OH)2(Ox)]- were identified, on the basis of the comparison of their corresponding g values with recent literature data. The kinetic analysis of the temporal evolution of the paramagnetic Cr(V) species indicates also an effective photocatalytic degradation of chromium(V) oxalate complexes. This new evidence reinforces previous findings regarding sequential one-electron-transfer processes in Cr(VI) photocatalytic reduction, suggesting that this route may represent a general behavior for the Cr(VI) reduction over UV-irradiated TiO2 particles.","Heterogeneous photocatalytic reduction of chromium(VI) over TiO2 particles in the presence of oxalate: involvement of Cr(V) species Abs: Cr(VI) photocatalytic reduction experiments over TiO2 particles under near UV irradiation in the presence of excess oxalate were performed at acid pH (2 and 3) and under air and N2 bubbling. Initial photonic efficiencies for Cr(VI) reduction are nearly the same under aerobic and anaerobic conditions, but show a significant increase at the lowest pH. At pH 2, the addition of oxalate facilitates Cr(VI) reduction, hindering the electron-shuttle mechanism taking place in pure water. The oxalate synergistic effect at pH 2 is lower than that previously found for EDTA and negligible at pH 3. Chromium(V) oxalate concentration profiles were obtained by EPR spectroscopy in the presence of excess oxalate at pH 1.5. Coordinated Cr(V) complexes [Cr(V)(O)(Ox)2]-, [Cr(V)(OH2)(Ox)2]-, and [Cr(V)(O)(OH)2(Ox)]- were identified, on the basis of the comparison of their corresponding g values with recent literature data. The kinetic analysis of the temporal evolution of the paramagnetic Cr(V) species indicates also an effective photocatalytic degradation of chromium(V) oxalate complexes. This new evidence reinforces previous findings regarding sequential one-electron-transfer processes in Cr(VI) photocatalytic reduction, suggesting that this route may represent a general behavior for the Cr(VI) reduction over UV-irradiated TiO2 particles."
1231979,Gunaratnam and  Grant 2004,Damage to F-actin and cell death induced by chromium VI and nickel in primary monolayer cultures of rat hepatocytes,"The toxicity of hexavalent chromium and nickel was investigated using primary cultures of hepatocytes as an in vitro system. Cr VI and Ni are widely used in the steel and orthopaedic implant industry. Although their toxicity has been extensively investigated, the mechanism(s) of action is/are not fully understood. Monolayer cultures of hepatocytes (10(5) cells/cm2) were exposed to various concentrations of Cr VI and Ni for 24 h. Cells were stained with phalloidin-FITC for the detection of the cytoskeletal component, F-actin, and Annexin V-FITC and propidium iodide for the detection of the mode of cell death. Exposure of cells to Cr VI (1, 5, 10 and 50 microM) resulted in the loss of the cell cytoskeleton, and this was accompanied by membrane blebbing and shrinking of the cell. Ni, on the other hand, induced detectable damage to the cytoskeleton only at 500 microM. Staining of the cells with Annexin V and propidium iodide showed that Cr VI induces apoptosis at low concentrations (5 microM), and necrosis at higher concentrations (25 and 50 microM). Ni almost exclusively induced necrosis at 500 microM with very few cells undergoing apoptosis. Below this concentration it had no discernable effect on hepatocytes. Damage to the cell cytoskeleton caused by Cr VI may be an early indication of apoptosis in hepatocytes.","Damage to F-actin and cell death induced by chromium VI and nickel in primary monolayer cultures of rat hepatocytes Abs: The toxicity of hexavalent chromium and nickel was investigated using primary cultures of hepatocytes as an in vitro system. Cr VI and Ni are widely used in the steel and orthopaedic implant industry. Although their toxicity has been extensively investigated, the mechanism(s) of action is/are not fully understood. Monolayer cultures of hepatocytes (10(5) cells/cm2) were exposed to various concentrations of Cr VI and Ni for 24 h. Cells were stained with phalloidin-FITC for the detection of the cytoskeletal component, F-actin, and Annexin V-FITC and propidium iodide for the detection of the mode of cell death. Exposure of cells to Cr VI (1, 5, 10 and 50 microM) resulted in the loss of the cell cytoskeleton, and this was accompanied by membrane blebbing and shrinking of the cell. Ni, on the other hand, induced detectable damage to the cytoskeleton only at 500 microM. Staining of the cells with Annexin V and propidium iodide showed that Cr VI induces apoptosis at low concentrations (5 microM), and necrosis at higher concentrations (25 and 50 microM). Ni almost exclusively induced necrosis at 500 microM with very few cells undergoing apoptosis. Below this concentration it had no discernable effect on hepatocytes. Damage to the cell cytoskeleton caused by Cr VI may be an early indication of apoptosis in hepatocytes."
1231978,Guha 2004,Biogeochemical influence on transport of chromium in manganese sediments: experimental and modeling approaches,"Hexavalent chromium (Cr(VI)) was reduced to immobile and nontoxic Cr(III) by a dissimilatory metal reducing bacteria, Shewanella alga Simidu (BrY-MT) ATCC 55627. A series of kinetic batch and dynamic column experiments were conducted to provide an understanding of Cr(VI) reduction by the facultative anaerobe BrY-MT. Reduction of Cr(VI) was rapid (within 1 h) in columns packed with quartz sand and bacteria, whereas Cr(VI) reduction by BrY-MT was delayed (57 h) in the presence of beta-MnO2-coated sand. A mathematical model was developed and evaluated against data obtained from column experiments. The model takes into account (1) advective-dispersive transport of Cr(III), Cr(VI), lactate, and protein (mobile and immobile bacteria); (2) first-order kinetic adsorption of Cr(III) and lactate; (3) conversion of solid phase beta-MnO2 to solid phase MnOOH due to oxidation of Cr(III); (4) dual-Monod kinetics, where Cr(VI) is the electron acceptor and lactate is the electron donor. The breakthrough data for Cr(III), Cr(VI), lactate, and protein (mobile and immobile bacteria) were fitted simultaneously. The breakthrough data are well described by the mathematical model that considers the above processes. This result demonstrates the ability of the coupled hydrobiogeochemical model to simulate chromium transport in complex reactive systems.","Biogeochemical influence on transport of chromium in manganese sediments: experimental and modeling approaches Abs: Hexavalent chromium (Cr(VI)) was reduced to immobile and nontoxic Cr(III) by a dissimilatory metal reducing bacteria, Shewanella alga Simidu (BrY-MT) ATCC 55627. A series of kinetic batch and dynamic column experiments were conducted to provide an understanding of Cr(VI) reduction by the facultative anaerobe BrY-MT. Reduction of Cr(VI) was rapid (within 1 h) in columns packed with quartz sand and bacteria, whereas Cr(VI) reduction by BrY-MT was delayed (57 h) in the presence of beta-MnO2-coated sand. A mathematical model was developed and evaluated against data obtained from column experiments. The model takes into account (1) advective-dispersive transport of Cr(III), Cr(VI), lactate, and protein (mobile and immobile bacteria); (2) first-order kinetic adsorption of Cr(III) and lactate; (3) conversion of solid phase beta-MnO2 to solid phase MnOOH due to oxidation of Cr(III); (4) dual-Monod kinetics, where Cr(VI) is the electron acceptor and lactate is the electron donor. The breakthrough data for Cr(III), Cr(VI), lactate, and protein (mobile and immobile bacteria) were fitted simultaneously. The breakthrough data are well described by the mathematical model that considers the above processes. This result demonstrates the ability of the coupled hydrobiogeochemical model to simulate chromium transport in complex reactive systems."
1231977,Janssens de Bisthoven et al. 2004,"Behavioral bioassay with a local tadpole (Pleuroderma cinereum) from River Rocha, Bolivia, in river water spiked with chromium6+",,"Behavioral bioassay with a local tadpole (Pleuroderma cinereum) from River Rocha, Bolivia, in river water spiked with chromium6+ Abs: "
1231975,Czakó-Vér et al. 2004,Characterization of chromate-sensitive and -tolerant mutants of Schizosaccharomyces pombe,"Stable chromium(VI)-sensitive and -tolerant mutants were obtained by induced mutagenesis of Schizosaccharomyces pombe lysine and leucine auxotrophic heterothallic strains 6chr+ and 9chr+. Eleven of them were selected for further studies. Fast transport of 51CrO4(2-) was detected in a representative sensitive mutant, chr-51S, while the tolerant mutant chr1-66T and the parental strain 6chr+ exhibited significantly lower 51CrO4(2-) uptake. The segregation of tetrads of three selected CrVI-tolerant mutants, chr1-66T, chr1-14T and chr2-04T, strongly indicated that tolerance was determined by single mutations. Random spore analysis proved that the mutations of chr1-66T and chr1-14T were allelic and the mutation of mutant chr2-04T was not allelic with the mutation of chr1-66T. Recombinants carrying the ura4D18 selective marker were created for transformation experiments. Two of them (chr1-661T and chr2-046T) can be used to clone and identify the genes responsible for their CrVI tolerance phenotype.","Characterization of chromate-sensitive and -tolerant mutants of Schizosaccharomyces pombe Abs: Stable chromium(VI)-sensitive and -tolerant mutants were obtained by induced mutagenesis of Schizosaccharomyces pombe lysine and leucine auxotrophic heterothallic strains 6chr+ and 9chr+. Eleven of them were selected for further studies. Fast transport of 51CrO4(2-) was detected in a representative sensitive mutant, chr-51S, while the tolerant mutant chr1-66T and the parental strain 6chr+ exhibited significantly lower 51CrO4(2-) uptake. The segregation of tetrads of three selected CrVI-tolerant mutants, chr1-66T, chr1-14T and chr2-04T, strongly indicated that tolerance was determined by single mutations. Random spore analysis proved that the mutations of chr1-66T and chr1-14T were allelic and the mutation of mutant chr2-04T was not allelic with the mutation of chr1-66T. Recombinants carrying the ura4D18 selective marker were created for transformation experiments. Two of them (chr1-661T and chr2-046T) can be used to clone and identify the genes responsible for their CrVI tolerance phenotype."
1231974,Sawada et al. 2004,Removal of Cr(VI) from contaminated soil by electrokinetic remediation,"A new process for the removal of hexavalent chromium [Cr(VI)] contaminated soil is described. The process provides for an efficient removal of anionic chemicals from contaminated soils. Chromate anions were removed from the soil to the anodic reservoir by the moving force of electromigration. In this process, the chromate anions that accumulate in the anodic reservoir are simultaneously eliminated by using a column packed adsorbent. The adsorbent (immobilized tannin) used was chemically incorporated into cellulose. Cr(VI) was found to be adsorbed to this adsorbent efficiently. In the electrokinetic process, the pH of the aqueous solution in the anodic reservoir was decreased by the electrolysis of water. In the present study, the pH of the solution in the anodic reservoir is maintained at pH 6 by the addition of an aqueous alkaline solution during the electrokinetic process. The advantage of pH control is that it promotes the release of Cr(VI) from the soil by electromigration, thus permitting the maximum adsorption of Cr(VI) on the immobilized tannin. Simultaneous collection of Cr(VI) from the anodic reservoir leads to the protection from secondary contamination with Cr(VI).","Removal of Cr(VI) from contaminated soil by electrokinetic remediation Abs: A new process for the removal of hexavalent chromium [Cr(VI)] contaminated soil is described. The process provides for an efficient removal of anionic chemicals from contaminated soils. Chromate anions were removed from the soil to the anodic reservoir by the moving force of electromigration. In this process, the chromate anions that accumulate in the anodic reservoir are simultaneously eliminated by using a column packed adsorbent. The adsorbent (immobilized tannin) used was chemically incorporated into cellulose. Cr(VI) was found to be adsorbed to this adsorbent efficiently. In the electrokinetic process, the pH of the aqueous solution in the anodic reservoir was decreased by the electrolysis of water. In the present study, the pH of the solution in the anodic reservoir is maintained at pH 6 by the addition of an aqueous alkaline solution during the electrokinetic process. The advantage of pH control is that it promotes the release of Cr(VI) from the soil by electromigration, thus permitting the maximum adsorption of Cr(VI) on the immobilized tannin. Simultaneous collection of Cr(VI) from the anodic reservoir leads to the protection from secondary contamination with Cr(VI)."
1231972,Hayashi et al. 2004,Signal transduction of p53-independent apoptotic pathway induced by hexavalent chromium in U937 cells,"It has been reported that the hexavalent chromium compound (Cr(VI)) can induce both p53-dependent and p53-independent apoptosis. While a considerable amount of information is available on the p53-dependent pathway, only little is known about the p53-independent pathway. To elucidate the p53-independent mechanism, the roles of the Ca(2+)-calpain- and mitochondria-caspase-dependent pathways in apoptosis induced by Cr(VI) were investigated. When human lymphoma U937 cells, p53 mutated cells, were treated with 20 microM Cr(VI) for 24 h, nuclear morphological changes and DNA fragmentation were observed. Production of hydroxyl radicals revealed by electron paramagnetic resonance (EPR)-spin trapping, and increase of intracellular calcium ion concentration monitored by digital imaging were also observed in Cr(VI)-treated cells. An intracellular Ca(2+) chelator, BAPTA-AM, and calpain inhibitors suppressed the Cr(VI)-induced DNA fragmentation. The number of cells showing low mitochondrial membrane potential (MMP), high level of superoxide anion radicals (O(2)(-)), and high activity of caspase-3, which are indicators of mitochondria-caspase-dependent pathway, increased significantly in Cr(VI)-treated cells. An antioxidant, N-acetyl-l-cysteine (NAC), decreased DNA fragmentation and inhibited the changes in MMP, O(2)(-) formation, and activation of caspase-3 induced by Cr(VI). No increase of the expressions of Fas and phosphorylated JNK was observed after Cr(VI) treatment. Cell cycle analysis revealed that the fraction of G2/M phase tended to increase after 24 h of treatment, suggesting that Cr(VI)-induced apoptosis is related to the G2 block. These results indicate that Ca(2+)-calpain- and mitochondria-caspase-dependent pathways play significant roles in the Cr(VI)-induced apoptosis via the G2 block, which are independent of JNK and Fas activation. The inhibition of apoptosis and all its signal transductions by NAC suggests that intracellular reactive oxygen species (ROS) are important for both pathways in Cr(VI)-induced apoptosis of U937 cell.","Signal transduction of p53-independent apoptotic pathway induced by hexavalent chromium in U937 cells Abs: It has been reported that the hexavalent chromium compound (Cr(VI)) can induce both p53-dependent and p53-independent apoptosis. While a considerable amount of information is available on the p53-dependent pathway, only little is known about the p53-independent pathway. To elucidate the p53-independent mechanism, the roles of the Ca(2+)-calpain- and mitochondria-caspase-dependent pathways in apoptosis induced by Cr(VI) were investigated. When human lymphoma U937 cells, p53 mutated cells, were treated with 20 microM Cr(VI) for 24 h, nuclear morphological changes and DNA fragmentation were observed. Production of hydroxyl radicals revealed by electron paramagnetic resonance (EPR)-spin trapping, and increase of intracellular calcium ion concentration monitored by digital imaging were also observed in Cr(VI)-treated cells. An intracellular Ca(2+) chelator, BAPTA-AM, and calpain inhibitors suppressed the Cr(VI)-induced DNA fragmentation. The number of cells showing low mitochondrial membrane potential (MMP), high level of superoxide anion radicals (O(2)(-)), and high activity of caspase-3, which are indicators of mitochondria-caspase-dependent pathway, increased significantly in Cr(VI)-treated cells. An antioxidant, N-acetyl-l-cysteine (NAC), decreased DNA fragmentation and inhibited the changes in MMP, O(2)(-) formation, and activation of caspase-3 induced by Cr(VI). No increase of the expressions of Fas and phosphorylated JNK was observed after Cr(VI) treatment. Cell cycle analysis revealed that the fraction of G2/M phase tended to increase after 24 h of treatment, suggesting that Cr(VI)-induced apoptosis is related to the G2 block. These results indicate that Ca(2+)-calpain- and mitochondria-caspase-dependent pathways play significant roles in the Cr(VI)-induced apoptosis via the G2 block, which are independent of JNK and Fas activation. The inhibition of apoptosis and all its signal transductions by NAC suggests that intracellular reactive oxygen species (ROS) are important for both pathways in Cr(VI)-induced apoptosis of U937 cell."
1231971,Trumble and  Jensen 2004,"Ovipositional response, developmental effects and toxicity of hexavalent chromium to Megaselia scalaris, a terrestrial detritivore","The effects of hexavalent chromium (Cr VI) on ovipositional response, development, and survival of a common terrestrial detritivore, Megaselia scalaris (Diptera: Phoridae), were assessed in the laboratory. Ovipositing females did not discriminate between substrates containing 0, 50, 500, or 1000 microg/g, indicating a lack of avoidance behavior. Eggs placed on artificial diets containing up to 1000 microg/g either did not absorb Cr VI or were unaffected as measured by eclosion rates. However, development and survival of larvae were significantly reduced at the higher concentrations tested. Concentrations of 500 microg/g in their food increased larval development times by nearly 65%. At 1000 microg/g, larval developmental times doubled. The time required from onset to completion of pupariation was not significantly different regardless of Cr VI concentration. Although males eclosed before females, there was no significant difference between the sexes in the time required for adult eclosion. In addition, there were no significant differences in the percentage of males and females emerging from any of the treatments. At concentrations of 500 or 1000 microg/g, Cr VI decreased larval survival. Survival was reduced by 44.3% at 500 microg/g as compared with the controls. There was no additional mortality from the onset of the puparial stage to adult eclosion for larvae fed diets containing 500 microg/g Cr VI. At 1000 microg/g Cr VI, larval survival decreased by 86.6%. An additional 7.4% mortality was recorded in the puparial stage, for a decrease in total survival (larval plus puparial stages) of 94%. Thus, nearly all of the observed mortality occurred during the larval stage rather than the puparial stage. The population level implications of lack of avoidance of contaminated food and the effects of increased developmental times and reduced survivorship are discussed.","Ovipositional response, developmental effects and toxicity of hexavalent chromium to Megaselia scalaris, a terrestrial detritivore Abs: The effects of hexavalent chromium (Cr VI) on ovipositional response, development, and survival of a common terrestrial detritivore, Megaselia scalaris (Diptera: Phoridae), were assessed in the laboratory. Ovipositing females did not discriminate between substrates containing 0, 50, 500, or 1000 microg/g, indicating a lack of avoidance behavior. Eggs placed on artificial diets containing up to 1000 microg/g either did not absorb Cr VI or were unaffected as measured by eclosion rates. However, development and survival of larvae were significantly reduced at the higher concentrations tested. Concentrations of 500 microg/g in their food increased larval development times by nearly 65%. At 1000 microg/g, larval developmental times doubled. The time required from onset to completion of pupariation was not significantly different regardless of Cr VI concentration. Although males eclosed before females, there was no significant difference between the sexes in the time required for adult eclosion. In addition, there were no significant differences in the percentage of males and females emerging from any of the treatments. At concentrations of 500 or 1000 microg/g, Cr VI decreased larval survival. Survival was reduced by 44.3% at 500 microg/g as compared with the controls. There was no additional mortality from the onset of the puparial stage to adult eclosion for larvae fed diets containing 500 microg/g Cr VI. At 1000 microg/g Cr VI, larval survival decreased by 86.6%. An additional 7.4% mortality was recorded in the puparial stage, for a decrease in total survival (larval plus puparial stages) of 94%. Thus, nearly all of the observed mortality occurred during the larval stage rather than the puparial stage. The population level implications of lack of avoidance of contaminated food and the effects of increased developmental times and reduced survivorship are discussed."
1231970,Parks et al. 2004,Determination of total chromium in environmental water samples,"It is often desirable to quantify both dissolved Cr(VI) and total Cr in samples accurately. Various protocols are now being utilized to quantify the amount of total chromium in natural waters and each of these has possible interferences. This study describes the shortcomings of each method when particulate iron is present in a water sample, and a more rigorous digestion protocol is tested. Data from bench studies as well as a field survey of 21 water utilities are presented. Additionally, field data from several hundred water utility samples are presented to illustrate the potential for incomplete recovery of total chromium using accepted protocols.","Determination of total chromium in environmental water samples Abs: It is often desirable to quantify both dissolved Cr(VI) and total Cr in samples accurately. Various protocols are now being utilized to quantify the amount of total chromium in natural waters and each of these has possible interferences. This study describes the shortcomings of each method when particulate iron is present in a water sample, and a more rigorous digestion protocol is tested. Data from bench studies as well as a field survey of 21 water utilities are presented. Additionally, field data from several hundred water utility samples are presented to illustrate the potential for incomplete recovery of total chromium using accepted protocols."
1231968,Wang and  Li 2004,High-temperature reduction of chromium (VI) in solid alkali,"Chromium (VI) that exists in many industrial wastes is considered highly toxic. One of the most common ways to dispose of these wastes is to reduce chromium (VI) to chromium (III), which is less toxic and can be relatively easily removed or fixed. However, the reduction of chromium (VI) is often conducted in acidic solutions and the chromium (VI) in alkaline solid wastes is hardly to be fully removed. The present study describes a new method for reducing chromium (VI) in alkaline solid. By mixing alkaline solids containing chromium (VI) with an aqueous sucrose solution and then calcinating the resulting mixture at 400-600 degrees C in inertial gas, chromium (VI) can be easily reduced to an insoluble chromium oxide. The reduced fraction can reach up to 99% in 10-20 min under the conditions of temperature above 600 degrees C and sucrose/chromium &gt; or = 1 g/1 g.","High-temperature reduction of chromium (VI) in solid alkali Abs: Chromium (VI) that exists in many industrial wastes is considered highly toxic. One of the most common ways to dispose of these wastes is to reduce chromium (VI) to chromium (III), which is less toxic and can be relatively easily removed or fixed. However, the reduction of chromium (VI) is often conducted in acidic solutions and the chromium (VI) in alkaline solid wastes is hardly to be fully removed. The present study describes a new method for reducing chromium (VI) in alkaline solid. By mixing alkaline solids containing chromium (VI) with an aqueous sucrose solution and then calcinating the resulting mixture at 400-600 degrees C in inertial gas, chromium (VI) can be easily reduced to an insoluble chromium oxide. The reduced fraction can reach up to 99% in 10-20 min under the conditions of temperature above 600 degrees C and sucrose/chromium &gt; or = 1 g/1 g."
1231967,Gonzalez-Serrano et al. 2004,Removal of water pollutants with activated carbons prepared from H3PO4 activation of lignin from kraft black liquors,"Activated carbons with a high BET surface area and a well-developed porosity have been prepared from pyrolysis of H3PO4-impregnated lignin precipitated from kraft black liquors. Impregnation ratios within the range of 1-3 and activation temperatures of 623-873 K have been used, giving rise to carbons with different porous and surface chemical structure. Increasing the activation temperature and the impregnation ratio leads to a widening of the porous structure with a higher relative contribution of mesoporosity. The potential application of these carbons for the removal of water pollutants has been investigated by measuring their adsorption capacities for phenol, 2,4,5-trichlorophenol and Cr (VI) as representative of toxic contaminants found in industrial wastewaters. The results obtained compare well and even favorably with those reported in the literature for other activated carbons. An impregnation ratio and an activation temperature around 2 g H3PO4/g lignin and 700 K, respectively, are recommended as the best combination of operating conditions to prepare activated carbons for aqueous phase applications although at lower values of these two variables carbons with good adsorption capacities are also obtained.","Removal of water pollutants with activated carbons prepared from H3PO4 activation of lignin from kraft black liquors Abs: Activated carbons with a high BET surface area and a well-developed porosity have been prepared from pyrolysis of H3PO4-impregnated lignin precipitated from kraft black liquors. Impregnation ratios within the range of 1-3 and activation temperatures of 623-873 K have been used, giving rise to carbons with different porous and surface chemical structure. Increasing the activation temperature and the impregnation ratio leads to a widening of the porous structure with a higher relative contribution of mesoporosity. The potential application of these carbons for the removal of water pollutants has been investigated by measuring their adsorption capacities for phenol, 2,4,5-trichlorophenol and Cr (VI) as representative of toxic contaminants found in industrial wastewaters. The results obtained compare well and even favorably with those reported in the literature for other activated carbons. An impregnation ratio and an activation temperature around 2 g H3PO4/g lignin and 700 K, respectively, are recommended as the best combination of operating conditions to prepare activated carbons for aqueous phase applications although at lower values of these two variables carbons with good adsorption capacities are also obtained."
1231966,Shakoori et al. 2004,"Multiple metal resistance in the ciliate protozoan, Vorticella microstoma, isolated from industrial effluents and its potential in bioremediation of toxic wastes",,"Multiple metal resistance in the ciliate protozoan, Vorticella microstoma, isolated from industrial effluents and its potential in bioremediation of toxic wastes Abs: "
1231965,Wang et al. 2004,Direct fluorescence quantification of chromium(VI) in wastewater with organic nanoparticles sensor,"Under ultrasonic irradiation, organic fluorescence nanoparticles have been prepared by a reprecipitation method. Compared with single organic fluorophores, these nanoparticles are brighter, more stable against photobleaching and more water-soluble. They also have high room-temperature fluorescence quantum yields (approximately 20%) and a long fluorescence lifetime (approximately 0.2 micros). Based on the fluorescence quenching of nanoparticles by chromium(VI), a method for the selective determination of chromium(VI) without the separation of chromium(III) in water was developed. Under the optimal conditions, the linear range of the calibration curve was 7.0 x 10(-6) - 1.0 x 10(-4) mol L(-1). The detection limit was 2.8 x 10(-6) mol L(-1). The method is characterized by a short reaction time, stable fluorescence signals, simplicity and high selectivity. The present assay has been applied to the selective quantification of Cr(VI) in wastewater with satisfactory results.","Direct fluorescence quantification of chromium(VI) in wastewater with organic nanoparticles sensor Abs: Under ultrasonic irradiation, organic fluorescence nanoparticles have been prepared by a reprecipitation method. Compared with single organic fluorophores, these nanoparticles are brighter, more stable against photobleaching and more water-soluble. They also have high room-temperature fluorescence quantum yields (approximately 20%) and a long fluorescence lifetime (approximately 0.2 micros). Based on the fluorescence quenching of nanoparticles by chromium(VI), a method for the selective determination of chromium(VI) without the separation of chromium(III) in water was developed. Under the optimal conditions, the linear range of the calibration curve was 7.0 x 10(-6) - 1.0 x 10(-4) mol L(-1). The detection limit was 2.8 x 10(-6) mol L(-1). The method is characterized by a short reaction time, stable fluorescence signals, simplicity and high selectivity. The present assay has been applied to the selective quantification of Cr(VI) in wastewater with satisfactory results."
1231963,NTP 2002,Chromium hexavalent compounds,,Chromium hexavalent compounds Abs: 
1231962,Nkhalambayausi-Chirwa and  Wang 2004,Modeling hexavalent chromium removal in a Bacillus sp. fixed-film bioreactor,"A one-dimensional diffusion-reaction model was developed to simulate Cr(VI) reduction in a Bacillus sp. pure culture biofilm reactor with glucose as a sole supplied carbon and energy source. Substrate utilization and Cr(VI) reduction in the biofilm was best represented by a system of (second-order) partial differential equations (PDEs). The PDE system was solved by the (fourth-order) Runge-Kutta method adjusted for mass transport resistance using the (second-order) Crank-Nicholson and Backward Euler finite difference methods. A heuristic procedure (genetic search algorithm) was used to find global optimum values of Cr(VI) reduction and substrate utilization rate kinetic parameters. The fixed-film bioreactor system yielded higher values of the maximum specific Cr(VI) reduction rate coefficient and Cr(VI) reduction capacity (kmc = 0.062 1/h, and Rc = 0.13 mg/mg, respectively) than previously determined in batch reactors (kmc = 0.022 1/h and Rc = 0.012 mg/mg). The model predicted effluent Cr(VI) concentration well with 98.9% confidence (sigmay2 = 2.37 mg2/L2, N = 119) and effluent glucose with 96.4 % confidence (sigmay(w)2 = 5402 mg2/L2, N = 121, w = 100) over a wide range of Cr(VI) loadings (10-498 mg Cr(VI)/L/d).","Modeling hexavalent chromium removal in a Bacillus sp. fixed-film bioreactor Abs: A one-dimensional diffusion-reaction model was developed to simulate Cr(VI) reduction in a Bacillus sp. pure culture biofilm reactor with glucose as a sole supplied carbon and energy source. Substrate utilization and Cr(VI) reduction in the biofilm was best represented by a system of (second-order) partial differential equations (PDEs). The PDE system was solved by the (fourth-order) Runge-Kutta method adjusted for mass transport resistance using the (second-order) Crank-Nicholson and Backward Euler finite difference methods. A heuristic procedure (genetic search algorithm) was used to find global optimum values of Cr(VI) reduction and substrate utilization rate kinetic parameters. The fixed-film bioreactor system yielded higher values of the maximum specific Cr(VI) reduction rate coefficient and Cr(VI) reduction capacity (kmc = 0.062 1/h, and Rc = 0.13 mg/mg, respectively) than previously determined in batch reactors (kmc = 0.022 1/h and Rc = 0.012 mg/mg). The model predicted effluent Cr(VI) concentration well with 98.9% confidence (sigmay2 = 2.37 mg2/L2, N = 119) and effluent glucose with 96.4 % confidence (sigmay(w)2 = 5402 mg2/L2, N = 121, w = 100) over a wide range of Cr(VI) loadings (10-498 mg Cr(VI)/L/d)."
1231961,Mulyani et al. 2004,Biomimetic oxidation of chromium(III): does the antidiabetic activity of chromium(III) involve carcinogenic chromium(VI)?,,Biomimetic oxidation of chromium(III): does the antidiabetic activity of chromium(III) involve carcinogenic chromium(VI)? Abs: 
1231960,Muranaka et al. 2004,Involvement of ceramide in the mechanism of Cr(VI)-induced apoptosis of CHO cells,"Mitochondria reduce Cr(VI) to Cr(V) with concomitant generation of reactive oxygen species, thereby exhibiting cytotoxic effects leading to apoptosis in various types of cells. To clarify the mechanism by which Cr(VI) induces apoptosis, we examined the effect of Cr(VI) on Chinese hamster ovary (CHO) cells. Cr(VI) increased cellular levels of ceramide by activating acid sphingomyelinase (ASMase) and inhibiting the phosphorylation of pleckstrin homology domain-containing protein kinase B (Akt). Cr(VI) also induced cyclosporin A- and trifluoperazine-sensitive depolarization of mitochondria and activated caspase-3, 8 and 9, thereby causing fragmentation of cellular DNA. The presence of desipramine, an inhibitor of ASMase, and membrane permeable pCPT-cAMP suppressed the Cr(VI)-induced activation of caspases and DNA fragmentation. These results suggested that accumulation of ceramide play an important role in the Cr(VI)-induced apoptosis of CHO cells through activation of mitochondrial membrane permeability transition.","Involvement of ceramide in the mechanism of Cr(VI)-induced apoptosis of CHO cells Abs: Mitochondria reduce Cr(VI) to Cr(V) with concomitant generation of reactive oxygen species, thereby exhibiting cytotoxic effects leading to apoptosis in various types of cells. To clarify the mechanism by which Cr(VI) induces apoptosis, we examined the effect of Cr(VI) on Chinese hamster ovary (CHO) cells. Cr(VI) increased cellular levels of ceramide by activating acid sphingomyelinase (ASMase) and inhibiting the phosphorylation of pleckstrin homology domain-containing protein kinase B (Akt). Cr(VI) also induced cyclosporin A- and trifluoperazine-sensitive depolarization of mitochondria and activated caspase-3, 8 and 9, thereby causing fragmentation of cellular DNA. The presence of desipramine, an inhibitor of ASMase, and membrane permeable pCPT-cAMP suppressed the Cr(VI)-induced activation of caspases and DNA fragmentation. These results suggested that accumulation of ceramide play an important role in the Cr(VI)-induced apoptosis of CHO cells through activation of mitochondrial membrane permeability transition."
1231959,Mignini et al. 2004,"Individual susceptibility to hexavalent chromium of workers of shoe, hide, and leather industries. Immunological pattern of HLA-B8, DR3-positive subjects","<strong>BACKGROUND: </strong>This study was designed to examine the effects of hexavalent chromium [Cr(VI)] on the immunological pattern of shoe, hide, and leather industry workers, moving from the hypothesis that some haplotypes (HLA-B8,DR3) can be important hidden risk cofactors.<br /><br /><strong>METHODS: </strong>Workplaces of 20 firms were monitored for total and respirable dusts and for total and hexavalent chromium. Cr(VI) on materials was also measured. Assay of chromium levels in blood and urine of 44 serological human leukocytes antigen (HLA)-typed workers (20 exposed, 15 HLA-B8,DR3-negative/5-positive and 24 non-exposed, 18 HLA-B8,DR3-negative/6-positive subjects) was performed by atomic absorption, and lymphocyte subsets (FACS-analysis), mitogen-mediate lympho-proliferation ([3H]thymidine incorporation), cytokine levels (ELISA), natural killer (NK) cytotoxic activity (51Cr-release assay) were determined.<br /><br /><strong>RESULTS: </strong>The environmental parameter levels are lower than threshold limit value-time-weighted average (TLV-TWA); in the materials, the Cr(VI) values exceeded the levels allowed. The peripheral blood mononuclear cells (PBMC) proliferation and the T-helper1 (TH1) cytokine pattern of subjects chronically exposed were significantly raised; addition in vitro of Cr(VI) further stimulated these parameters and in general the entire TH1 system and NK activity. The TH2 system was unaltered. In the HLA-B8,DR3-positive workers, immunologically &quot;low responders&quot;, the addition of Cr(VI) in vitro caused a further reduction of the considered parameters in the exposed subjects with a dramatic deficit of the TH1 system.<br /><br /><strong>CONCLUSIONS: </strong>Results indicate the unsuitability of TLV-TWA as a line of demarcation between safe and dangerous Cr(VI) concentrations and the importance of individual genetic susceptibility for occupational and preventative medicine. In particular, the presence of the HLA-B8,DR3 alleles can represent an important cofactor of immunotoxic susceptibility consequent to chronic low-dose Cr(VI) exposure.","Individual susceptibility to hexavalent chromium of workers of shoe, hide, and leather industries. Immunological pattern of HLA-B8, DR3-positive subjects Abs: <strong>BACKGROUND: </strong>This study was designed to examine the effects of hexavalent chromium [Cr(VI)] on the immunological pattern of shoe, hide, and leather industry workers, moving from the hypothesis that some haplotypes (HLA-B8,DR3) can be important hidden risk cofactors.<br /><br /><strong>METHODS: </strong>Workplaces of 20 firms were monitored for total and respirable dusts and for total and hexavalent chromium. Cr(VI) on materials was also measured. Assay of chromium levels in blood and urine of 44 serological human leukocytes antigen (HLA)-typed workers (20 exposed, 15 HLA-B8,DR3-negative/5-positive and 24 non-exposed, 18 HLA-B8,DR3-negative/6-positive subjects) was performed by atomic absorption, and lymphocyte subsets (FACS-analysis), mitogen-mediate lympho-proliferation ([3H]thymidine incorporation), cytokine levels (ELISA), natural killer (NK) cytotoxic activity (51Cr-release assay) were determined.<br /><br /><strong>RESULTS: </strong>The environmental parameter levels are lower than threshold limit value-time-weighted average (TLV-TWA); in the materials, the Cr(VI) values exceeded the levels allowed. The peripheral blood mononuclear cells (PBMC) proliferation and the T-helper1 (TH1) cytokine pattern of subjects chronically exposed were significantly raised; addition in vitro of Cr(VI) further stimulated these parameters and in general the entire TH1 system and NK activity. The TH2 system was unaltered. In the HLA-B8,DR3-positive workers, immunologically &quot;low responders&quot;, the addition of Cr(VI) in vitro caused a further reduction of the considered parameters in the exposed subjects with a dramatic deficit of the TH1 system.<br /><br /><strong>CONCLUSIONS: </strong>Results indicate the unsuitability of TLV-TWA as a line of demarcation between safe and dangerous Cr(VI) concentrations and the importance of individual genetic susceptibility for occupational and preventative medicine. In particular, the presence of the HLA-B8,DR3 alleles can represent an important cofactor of immunotoxic susceptibility consequent to chronic low-dose Cr(VI) exposure."
1231955,Sobrero et al. 2004,"Comparative response of Lemnaceae clones to copper(II), chromium(VI), and cadmium(II) toxicity",,"Comparative response of Lemnaceae clones to copper(II), chromium(VI), and cadmium(II) toxicity Abs: "
1231954,Roberts and  Oris 2004,Multiple biomarker response in rainbow trout during exposure to hexavalent chromium,"This research investigated hexavalent chromium toxicity in rainbow trout using a panel of biomarkers at different levels of biological organization. A time-course experiment in which rainbow trout were exposed in hard water (63.5 mg/L CaCO3) to a sublethal concentration of hexavalent chromium (10 mg/L) for a period of 28 days was conducted. The responses of multiple biomarkers were measured in gill and liver tissues at varying time points. Significant differences in metallothionein induction, superoxide dismutase activity, lipid peroxidation, cellular morphology, and growth were observed. Results indicated that gill tissues were more sensitive than hepatic tissues to chromium toxicity, yet hepatic tissues appeared to play a larger role in the organism's adaptive response to chromium compared to gill tissues. This study highlights the importance of using a set of integrated biomarkers to assess contaminant exposure and effects.","Multiple biomarker response in rainbow trout during exposure to hexavalent chromium Abs: This research investigated hexavalent chromium toxicity in rainbow trout using a panel of biomarkers at different levels of biological organization. A time-course experiment in which rainbow trout were exposed in hard water (63.5 mg/L CaCO3) to a sublethal concentration of hexavalent chromium (10 mg/L) for a period of 28 days was conducted. The responses of multiple biomarkers were measured in gill and liver tissues at varying time points. Significant differences in metallothionein induction, superoxide dismutase activity, lipid peroxidation, cellular morphology, and growth were observed. Results indicated that gill tissues were more sensitive than hepatic tissues to chromium toxicity, yet hepatic tissues appeared to play a larger role in the organism's adaptive response to chromium compared to gill tissues. This study highlights the importance of using a set of integrated biomarkers to assess contaminant exposure and effects."
1231953,Legrand et al. 2004,Reduction of aqueous chromate by Fe(II)/Fe(III) carbonate green rust: kinetic and mechanistic studies,"This work describes the heterogeneous reaction between FeII in carbonate green rust and aqueous chromate, in NaHCO3 solutions at 25 degrees C, and at pH values of 9.3-9.6. Evidence for reduction of CrVI to CrIII and concomitant solid-state oxidation of lattice FeII to FeIII was found from FeII titration and from structural analysis of the solids using FTIR, XRD, SEM, and XPS methods. Results indicate the formation of ferric oxyhydroxycarbonate and the concomitant precipitation of CrIII monolayers at the surface of the iron compound that induce passivation effects and progressive rate limitations. The number of CrIII monolayers formed at the completion of the reaction depends on [FeII]t=0, the molar concentration of FeII(solid) at t=0; on [n(o)]t=0, the molar concentration of reaction sites present at the surface of the solid phase at t=0; and on [CrVI]t=0, the molar concentration of CrVI at t=0. Kinetic data were modeled using a model based on the formation of successive CrIII monolayers, -(d[CrVI]/dt) = sigma(1)j k(i)[S] [CrVI]([n(i - 1)] - [n(i)]) with k(i)[S] (in s(-1) L mol(-1)), the rate coefficient of formation of CrIII monolayer i, and [n(i)] and [n(i - 1)], the molar concentration of CrIII precipitated in monolayer i and monolayer i - 1, respectively. Good matching curves were obtained with kinetic coefficients: k(1)[S] = 5-8 x 10(-4), k(2)[S] = 0.5-3 x 10(-5), and k(3)[S] about 1.7 x 10(-6) s(-1) m(-2) L. The CrVI removal efficiency progressively decreases along with the accumulation of CrIII monolayers at the surface of carbonate green rust particles. In the case of thick green rust particles resulting from the corrosion of iron in permeable reactive barriers, the quantity of FeII readily accessible for efficient CrVI removal should be rather low.","Reduction of aqueous chromate by Fe(II)/Fe(III) carbonate green rust: kinetic and mechanistic studies Abs: This work describes the heterogeneous reaction between FeII in carbonate green rust and aqueous chromate, in NaHCO3 solutions at 25 degrees C, and at pH values of 9.3-9.6. Evidence for reduction of CrVI to CrIII and concomitant solid-state oxidation of lattice FeII to FeIII was found from FeII titration and from structural analysis of the solids using FTIR, XRD, SEM, and XPS methods. Results indicate the formation of ferric oxyhydroxycarbonate and the concomitant precipitation of CrIII monolayers at the surface of the iron compound that induce passivation effects and progressive rate limitations. The number of CrIII monolayers formed at the completion of the reaction depends on [FeII]t=0, the molar concentration of FeII(solid) at t=0; on [n(o)]t=0, the molar concentration of reaction sites present at the surface of the solid phase at t=0; and on [CrVI]t=0, the molar concentration of CrVI at t=0. Kinetic data were modeled using a model based on the formation of successive CrIII monolayers, -(d[CrVI]/dt) = sigma(1)j k(i)[S] [CrVI]([n(i - 1)] - [n(i)]) with k(i)[S] (in s(-1) L mol(-1)), the rate coefficient of formation of CrIII monolayer i, and [n(i)] and [n(i - 1)], the molar concentration of CrIII precipitated in monolayer i and monolayer i - 1, respectively. Good matching curves were obtained with kinetic coefficients: k(1)[S] = 5-8 x 10(-4), k(2)[S] = 0.5-3 x 10(-5), and k(3)[S] about 1.7 x 10(-6) s(-1) m(-2) L. The CrVI removal efficiency progressively decreases along with the accumulation of CrIII monolayers at the surface of carbonate green rust particles. In the case of thick green rust particles resulting from the corrosion of iron in permeable reactive barriers, the quantity of FeII readily accessible for efficient CrVI removal should be rather low."
1231952,Farrell and  Breslin 2004,Reduction of Cr(VI) at a polyaniline film: influence of film thickness and oxidation state,"Hexavalent chromium [Cr(VI)] is highly toxic, carcinogenic, and mutagenic to living organisms. In this paper, the reduction of Cr(VI) to the much less toxic trivalent state [Cr(III)] was studied at polyaniline films grown to different thickness. Much higher rates of Cr(VI) reduction were observed for the &quot;thick&quot; polyaniline films. This was explained in terms of the morphology of the polymer and the higher surface area of polymer in contact with the Cr(VI) solution. For &quot;thin&quot; polyaniline films, the Cr(VI) reduction reaction was found to obey pseudo-first-order kinetics for the duration of exposure. However, in the case of thick polyaniline layers, the Cr(VI) reduction reaction followed a two-stage process, with each stage obeying pseudo-first-order kinetics. This was explained in terms of oxidation of the polymer from the leucoemeraldine to the emeraldine state and then further oxidation of the polymer from the emeraldine to the pernigraniline state. Much higher rates of Cr(VI) reduction were observed on oxidation of the polymer from the leucoemeraldine to the emeraldine state.","Reduction of Cr(VI) at a polyaniline film: influence of film thickness and oxidation state Abs: Hexavalent chromium [Cr(VI)] is highly toxic, carcinogenic, and mutagenic to living organisms. In this paper, the reduction of Cr(VI) to the much less toxic trivalent state [Cr(III)] was studied at polyaniline films grown to different thickness. Much higher rates of Cr(VI) reduction were observed for the &quot;thick&quot; polyaniline films. This was explained in terms of the morphology of the polymer and the higher surface area of polymer in contact with the Cr(VI) solution. For &quot;thin&quot; polyaniline films, the Cr(VI) reduction reaction was found to obey pseudo-first-order kinetics for the duration of exposure. However, in the case of thick polyaniline layers, the Cr(VI) reduction reaction followed a two-stage process, with each stage obeying pseudo-first-order kinetics. This was explained in terms of oxidation of the polymer from the leucoemeraldine to the emeraldine state and then further oxidation of the polymer from the emeraldine to the pernigraniline state. Much higher rates of Cr(VI) reduction were observed on oxidation of the polymer from the leucoemeraldine to the emeraldine state."
1231951,Orescanin et al. 2004,Purification of electroplating wastewaters utilizing waste by-product ferrous sulfate and wood fly ash,"A new procedure for electroplating wastewater treatment using waste by-product (ferrous-sulfate) and waste (wood fly ash) is presented. Ferrous-sulfate was employed for Cr(VI) reduction whereas neutralization and heavy metal removal from electroplating wastewaters was performed using wood fly ash. Heavy metal removal efficiency varied from 97.5% for Cu to 99.973% for Zn. Satisfying results can be achieved already at the pH 8. The method is suitable for the purposes of wastewater treatment and disposal in compliance with environmental laws. Furthermore, it is technically simple, cost-efficient and requires less space compared to the classical methodology. According to the composition of its water extractable fraction remaining waste ash could be safely deposited on domestic waste repositories.","Purification of electroplating wastewaters utilizing waste by-product ferrous sulfate and wood fly ash Abs: A new procedure for electroplating wastewater treatment using waste by-product (ferrous-sulfate) and waste (wood fly ash) is presented. Ferrous-sulfate was employed for Cr(VI) reduction whereas neutralization and heavy metal removal from electroplating wastewaters was performed using wood fly ash. Heavy metal removal efficiency varied from 97.5% for Cu to 99.973% for Zn. Satisfying results can be achieved already at the pH 8. The method is suitable for the purposes of wastewater treatment and disposal in compliance with environmental laws. Furthermore, it is technically simple, cost-efficient and requires less space compared to the classical methodology. According to the composition of its water extractable fraction remaining waste ash could be safely deposited on domestic waste repositories."
1231950,Asatiani et al. 2004,Effect of chromium(VI) action on Arthrobacter oxydans,"Arthrobacter species is of interest because of its high potential for bioremediation. Bacteria can detoxify chromium, by either reduction or accumulation inside the bacteria and/or absorption of chromium(VI) (CrVI) on their surface, and efflux pump. The possible pathway of Cr(VI) reduction by Arthrobacter oxydans isolated from Columbia basalt rocks at a US DOE highly contaminated site (USA) has been considered in the present study. FTIR absorption spectroscopy showed that these bacteria reduce Cr(VI). In the present study the threshold Cr(VI) nontoxic concentration (35 microg/mL) for A. oxydans growing in liquid medium was estimated. Complete uptake of this concentration was achieved in about 10 days after chromium addition into the medium. At this concentration an increase in the protein isolated from the cell wall of A. oxydans was observed. This increased protein predominated independently of the growth phase at which Cr(VI) was added. Thermal analysis was used to identify any influence of Cr(VI) on the DNP complex of A. oxydans. According to the data obtained it can be supposed that Cr(VI) reduction predominantly occurs on the bacterial surface and that cell wall represents a permeable barrier for these bacteria at the non-toxic chromium action.","Effect of chromium(VI) action on Arthrobacter oxydans Abs: Arthrobacter species is of interest because of its high potential for bioremediation. Bacteria can detoxify chromium, by either reduction or accumulation inside the bacteria and/or absorption of chromium(VI) (CrVI) on their surface, and efflux pump. The possible pathway of Cr(VI) reduction by Arthrobacter oxydans isolated from Columbia basalt rocks at a US DOE highly contaminated site (USA) has been considered in the present study. FTIR absorption spectroscopy showed that these bacteria reduce Cr(VI). In the present study the threshold Cr(VI) nontoxic concentration (35 microg/mL) for A. oxydans growing in liquid medium was estimated. Complete uptake of this concentration was achieved in about 10 days after chromium addition into the medium. At this concentration an increase in the protein isolated from the cell wall of A. oxydans was observed. This increased protein predominated independently of the growth phase at which Cr(VI) was added. Thermal analysis was used to identify any influence of Cr(VI) on the DNP complex of A. oxydans. According to the data obtained it can be supposed that Cr(VI) reduction predominantly occurs on the bacterial surface and that cell wall represents a permeable barrier for these bacteria at the non-toxic chromium action."
1231949,Park et al. 2004,Reduction of hexavalent chromium with the brown seaweed Ecklonia biomass,"A new type of biomass, protonated brown seaweed Ecklonia sp., was used for the removal of Cr(VI). When synthetic wastewater containing Cr(VI) was placed in contact with the biomass, the Cr(VI) was completely reduced to Cr(III). The converted Cr(III) appeared in the solution phase or was partly bound to the biomass. The Cr(VI) removal efficiency was always 100% in the pH range of this study (pH 1 to approximately 5). Furthermore, the Cr(VI) reduction was independent of the Cr(III) concentration, the reaction product, suggesting that the reaction was an irreversible process under our conditions. Proton ions were consumed in the ratio of 1.15 +/- 0.02 mol of protons/mol of Cr(VI), and the rate of Cr(VI) reduction increased with decreasing the pH. An optimum pH existed for the removal efficiency of total chromium (Cr(VI) plus Cr(III)), but this increased with contact time, eventually reaching approximately pH 4 when the reaction was complete. The electrons required for the Cr(VI) reduction also caused the oxidation of the organic compounds in the biomass. One gram of the biomass could reduce 4.49 +/- 0.12 mmol of Cr(VI). From a practical viewpoint, the abundant and inexpensive Ecklonia biomass could be used for the conversion of toxic Cr(VI) into less toxic or nontoxic Cr(III).","Reduction of hexavalent chromium with the brown seaweed Ecklonia biomass Abs: A new type of biomass, protonated brown seaweed Ecklonia sp., was used for the removal of Cr(VI). When synthetic wastewater containing Cr(VI) was placed in contact with the biomass, the Cr(VI) was completely reduced to Cr(III). The converted Cr(III) appeared in the solution phase or was partly bound to the biomass. The Cr(VI) removal efficiency was always 100% in the pH range of this study (pH 1 to approximately 5). Furthermore, the Cr(VI) reduction was independent of the Cr(III) concentration, the reaction product, suggesting that the reaction was an irreversible process under our conditions. Proton ions were consumed in the ratio of 1.15 +/- 0.02 mol of protons/mol of Cr(VI), and the rate of Cr(VI) reduction increased with decreasing the pH. An optimum pH existed for the removal efficiency of total chromium (Cr(VI) plus Cr(III)), but this increased with contact time, eventually reaching approximately pH 4 when the reaction was complete. The electrons required for the Cr(VI) reduction also caused the oxidation of the organic compounds in the biomass. One gram of the biomass could reduce 4.49 +/- 0.12 mmol of Cr(VI). From a practical viewpoint, the abundant and inexpensive Ecklonia biomass could be used for the conversion of toxic Cr(VI) into less toxic or nontoxic Cr(III)."
1231947,Alguacil et al. 2004,The phosphine oxides Cyanex 921 and Cyanex 923 as carriers for facilitated transport of chromium (VI)-chloride aqueous solutions,"The behaviour of the phosphine oxides Cyanex 921 and Cyanex 923 in the facilitated transport of chromium (VI) from chloride solutions is described. Transport is studied as a function of several variables such as stirring speeds of the aqueous phases, membrane phase diluent, hydrochloric acid concentration in the source phase and chromium and carrier concentrations. The separation of chromium (VI) from other metals presented in the source phase as well as the behaviour of phosphine oxides with respect to other neutral organophosphorous derivatives (tri-n-butylphosphate (TBP) and dibutyl butylphosphonate (DBBP)) are also investigated. Moreover, by using hydrazine sulphate in the receiving phase, Cr(VI) is immediately reduced to the less toxic Cr(III).","The phosphine oxides Cyanex 921 and Cyanex 923 as carriers for facilitated transport of chromium (VI)-chloride aqueous solutions Abs: The behaviour of the phosphine oxides Cyanex 921 and Cyanex 923 in the facilitated transport of chromium (VI) from chloride solutions is described. Transport is studied as a function of several variables such as stirring speeds of the aqueous phases, membrane phase diluent, hydrochloric acid concentration in the source phase and chromium and carrier concentrations. The separation of chromium (VI) from other metals presented in the source phase as well as the behaviour of phosphine oxides with respect to other neutral organophosphorous derivatives (tri-n-butylphosphate (TBP) and dibutyl butylphosphonate (DBBP)) are also investigated. Moreover, by using hydrazine sulphate in the receiving phase, Cr(VI) is immediately reduced to the less toxic Cr(III)."
1231946,Xu et al. 2004,Reduction of hexavalent chromium by ascorbic acid in aqueous solutions,"Hexavalent chromium is a priority pollutant in the USA and many other countries. Reduction of Cr(VI) to Cr(III) is environmentally favorable as the latter species is not toxic to most living organisms and also has a low mobility and bioavailability. Reduction of Cr(VI) by ascorbic acid (vitamin C) as a reductant was studied using potassium dichromate solution as the model pollutant. Effects of concentration of vitamin C, pH, temperature, irradiation and reaction time on the reduction of Cr(VI) were examined. Cr(VI) might be reduced by vitamin C not only in acidic conditions but also in weakly alkaline solutions. The reduction of Cr(VI) by vitamin C might occur not only under irradiation but also in the dark. Vitamin C is an important biological reductant in humans and animals, and not toxic. It is water-soluble and can easily permeate through various types of soils. The results indicate that vitamin C could be used in effective remediation of Cr(VI)-contaminated soils and groundwater in a wide range of pH, with or without sunlight.","Reduction of hexavalent chromium by ascorbic acid in aqueous solutions Abs: Hexavalent chromium is a priority pollutant in the USA and many other countries. Reduction of Cr(VI) to Cr(III) is environmentally favorable as the latter species is not toxic to most living organisms and also has a low mobility and bioavailability. Reduction of Cr(VI) by ascorbic acid (vitamin C) as a reductant was studied using potassium dichromate solution as the model pollutant. Effects of concentration of vitamin C, pH, temperature, irradiation and reaction time on the reduction of Cr(VI) were examined. Cr(VI) might be reduced by vitamin C not only in acidic conditions but also in weakly alkaline solutions. The reduction of Cr(VI) by vitamin C might occur not only under irradiation but also in the dark. Vitamin C is an important biological reductant in humans and animals, and not toxic. It is water-soluble and can easily permeate through various types of soils. The results indicate that vitamin C could be used in effective remediation of Cr(VI)-contaminated soils and groundwater in a wide range of pH, with or without sunlight."
1231945,Kemner et al. 2004,Elemental and redox analysis of single bacterial cells by x-ray microbeam analysis,"High-energy x-ray fluorescence measurements were used to make elemental maps and qualitative chemical analyses of individual Pseudomonas fluorescens strain NCIMB 11764 cells. Marked differences between planktonic and adhered cells were seen in the morphology, elemental composition, and sensitivity to Cr(VI) of hydrated cells at spatial scales of 150 nm. This technology can be applied to natural geomicrobiological systems.","Elemental and redox analysis of single bacterial cells by x-ray microbeam analysis Abs: High-energy x-ray fluorescence measurements were used to make elemental maps and qualitative chemical analyses of individual Pseudomonas fluorescens strain NCIMB 11764 cells. Marked differences between planktonic and adhered cells were seen in the morphology, elemental composition, and sensitivity to Cr(VI) of hydrated cells at spatial scales of 150 nm. This technology can be applied to natural geomicrobiological systems."
1231944,Stasinakis et al. 2004,Investigation of Cr(VI) reduction in continuous-flow activated sludge systems,"The aim of this research was to investigate hexavalent chromium, Cr(VI), reduction by activated sludge and to evaluate the use of continuous-flow activated sludge systems for the treatment of Cr(VI)-containing wastewater. Three series of experiments were conducted using two parallel lab-scale activated sludge systems. During the first experiment, one system was used as a control, while the other received Cr(VI) concentrations equal to 0.5, 1, 3 and 5mg l(-1). For all concentrations added, approximately 40% of the added Cr(VI) was removed during the activated sludge process. Determination of chromium species in the dissolved and particulate phase revealed that the removed Cr(VI) was sorbed by the activated sludge flocs mainly as trivalent chromium, Cr(III), while the residual chromium in the dissolved phase was mainly detected as Cr(VI). Activated sludge ability to reduce Cr(VI) was independent of the acclimatization of biomass to Cr(VI) and it was not affected by the toxic effect of Cr(VI) on autotrophic and heterotrophic microorganisms. During the second experiment, both systems were operated under two different hydraulic residence time (theta equal to 20 and 28h) and three different initial organic substrate concentration (COD equal to 300, 150 and 0mg l(-1)). Cr(VI) reduction was favored by an increase of theta, while it was limited by influent COD concentration. Finally, at the last experiment the effect of anoxic and anaerobic reactors on Cr(VI) reduction was investigated. It was observed that the use of an anoxic zone or an anaerobic-anoxic zone ahead of the aerobic reactor favored Cr(VI) reduction, increasing mean percentage Cr(VI) reduction to almost 80%.","Investigation of Cr(VI) reduction in continuous-flow activated sludge systems Abs: The aim of this research was to investigate hexavalent chromium, Cr(VI), reduction by activated sludge and to evaluate the use of continuous-flow activated sludge systems for the treatment of Cr(VI)-containing wastewater. Three series of experiments were conducted using two parallel lab-scale activated sludge systems. During the first experiment, one system was used as a control, while the other received Cr(VI) concentrations equal to 0.5, 1, 3 and 5mg l(-1). For all concentrations added, approximately 40% of the added Cr(VI) was removed during the activated sludge process. Determination of chromium species in the dissolved and particulate phase revealed that the removed Cr(VI) was sorbed by the activated sludge flocs mainly as trivalent chromium, Cr(III), while the residual chromium in the dissolved phase was mainly detected as Cr(VI). Activated sludge ability to reduce Cr(VI) was independent of the acclimatization of biomass to Cr(VI) and it was not affected by the toxic effect of Cr(VI) on autotrophic and heterotrophic microorganisms. During the second experiment, both systems were operated under two different hydraulic residence time (theta equal to 20 and 28h) and three different initial organic substrate concentration (COD equal to 300, 150 and 0mg l(-1)). Cr(VI) reduction was favored by an increase of theta, while it was limited by influent COD concentration. Finally, at the last experiment the effect of anoxic and anaerobic reactors on Cr(VI) reduction was investigated. It was observed that the use of an anoxic zone or an anaerobic-anoxic zone ahead of the aerobic reactor favored Cr(VI) reduction, increasing mean percentage Cr(VI) reduction to almost 80%."
1231943,Hu et al. 2004,"Chromium(VI) enhances (+/-)-anti-7beta,8alpha-dihydroxy-9alpha,10alpha-epoxy-7,8,9,10-tetrahydrobenzo[a]pyrene-induced cytotoxicity and mutagenicity in mammalian cells through its inhibitory effect on nucleotide excision repair","Chromium(VI) [Cr(VI)], a ubiquitous environmental contaminant, is a well-known carcinogen to both humans and experimental animals, although it is a weak mutagen by itself. Occupational exposure to Cr(VI) is strongly associated with a high incidence of lung cancer, but the underlying mechanisms remain unclear. Tobacco smoking is the major cause of lung cancer, and polycyclic aromatic hydrocarbons (PAHs) in tobacco smoke are the major etiological agents. Since humans are frequently exposed to both Cr(VI) and PAHs, it is possible that Cr(VI) and PAHs have a synergistic effect on mutagenecity and cytotoxicity that contributes to the high incidence of lung cancer associated with exposure to both agents. In this study, we tested this possibility by determining the effect of Cr(VI) exposure on (+/-)-anti-7beta,8alpha-dihydroxy-9alpha,10alpha-epoxy-7,8,9,10-tetrahydrobenzo[a]pyrene (BPDE, an active metabolite of PAHs) induced cytotoxicity, mutagenicity, and DNA adduct formation in Chinese hamster ovary (CHO) cells. Using the adenine phosphoribosyltransferase (APRT(+)) --&gt; APRT(-) forward mutation assay, we found that while Cr(VI) alone induced low mutation frequency, it greatly enhanced BPDE-induced mutations in nucleotide excision repair (NER)-proficient CHO cells. Cr(VI) exposure also greatly enhanced BPDE-induced killing in NER-proficient cells. It is known that the cytotoxicity and mutagenicity of BPDE are mainly caused by the formation of DNA adduct, which are removed by NER. To test the possibility that the enhancement of cytotoxicity and mutagenicity by Cr(VI) is caused by the inhibition of NER, NER-deficient cells were used, and the enhancement effects of Cr(VI) were not observed in those cells. We further found that while Cr(VI) exposure does not change the total BPDE-DNA adduct formation, it significantly inhibited the repair of BPDE-DNA adducts from genomic DNA in NER-proficient cells. Using a host cell reactivation assay, we found that the repair of BPDE-DNA adduct in a luciferase reporter gene is greatly inhibited after Cr(VI) exposure in NER-proficient cells while not in NER-deficient cells. Together these results clearly demonstrate that Cr(VI) exposure can greatly enhance the mutagenicity and cytotoxicity of PAHs by inhibiting the cellular NER pathway, and this may constitute an important mechanism for Cr(VI)-induced human carcinogenesis.","Chromium(VI) enhances (+/-)-anti-7beta,8alpha-dihydroxy-9alpha,10alpha-epoxy-7,8,9,10-tetrahydrobenzo[a]pyrene-induced cytotoxicity and mutagenicity in mammalian cells through its inhibitory effect on nucleotide excision repair Abs: Chromium(VI) [Cr(VI)], a ubiquitous environmental contaminant, is a well-known carcinogen to both humans and experimental animals, although it is a weak mutagen by itself. Occupational exposure to Cr(VI) is strongly associated with a high incidence of lung cancer, but the underlying mechanisms remain unclear. Tobacco smoking is the major cause of lung cancer, and polycyclic aromatic hydrocarbons (PAHs) in tobacco smoke are the major etiological agents. Since humans are frequently exposed to both Cr(VI) and PAHs, it is possible that Cr(VI) and PAHs have a synergistic effect on mutagenecity and cytotoxicity that contributes to the high incidence of lung cancer associated with exposure to both agents. In this study, we tested this possibility by determining the effect of Cr(VI) exposure on (+/-)-anti-7beta,8alpha-dihydroxy-9alpha,10alpha-epoxy-7,8,9,10-tetrahydrobenzo[a]pyrene (BPDE, an active metabolite of PAHs) induced cytotoxicity, mutagenicity, and DNA adduct formation in Chinese hamster ovary (CHO) cells. Using the adenine phosphoribosyltransferase (APRT(+)) --&gt; APRT(-) forward mutation assay, we found that while Cr(VI) alone induced low mutation frequency, it greatly enhanced BPDE-induced mutations in nucleotide excision repair (NER)-proficient CHO cells. Cr(VI) exposure also greatly enhanced BPDE-induced killing in NER-proficient cells. It is known that the cytotoxicity and mutagenicity of BPDE are mainly caused by the formation of DNA adduct, which are removed by NER. To test the possibility that the enhancement of cytotoxicity and mutagenicity by Cr(VI) is caused by the inhibition of NER, NER-deficient cells were used, and the enhancement effects of Cr(VI) were not observed in those cells. We further found that while Cr(VI) exposure does not change the total BPDE-DNA adduct formation, it significantly inhibited the repair of BPDE-DNA adducts from genomic DNA in NER-proficient cells. Using a host cell reactivation assay, we found that the repair of BPDE-DNA adduct in a luciferase reporter gene is greatly inhibited after Cr(VI) exposure in NER-proficient cells while not in NER-deficient cells. Together these results clearly demonstrate that Cr(VI) exposure can greatly enhance the mutagenicity and cytotoxicity of PAHs by inhibiting the cellular NER pathway, and this may constitute an important mechanism for Cr(VI)-induced human carcinogenesis."
1231941,Krumschnabel and  Nawaz 2004,Acute toxicity of hexavalent chromium in isolated teleost hepatocytes,"Acute toxic effects of hexavalent chromium [Cr(VI)], a widely recognised carcinogenic, mutagenic and redox active metal, were investigated in isolated hepatocytes of goldfish (Carassius auratus). Exposure to 250 microM Cr(VI) induced a significant decrease of cell viability from 94% in controls to 88% and 84% after 30 min and 4 h of exposure, respectively. Cr-toxicity was associated with a concentration-dependent stimulation of the formation of reactive oxygen species (ROS). As one potential source of ROS formation we identified the lysosomal Fe(2+) pool, since the ferric ion chelator deferoxamin inhibited ROS formation by approximately 15%. Lysosomal membranes remained nevertheless intact during Cr-exposure, as determined from neutral red retention in this compartment. Another significant source of ROS appear to be the mitochondria, where a presumably uncoupled increase of respiration by 20-30% was triggered by the metal. Inhibition of mitochondrial respiration by cyanide caused an approximately 40% decrease of Cr-induced ROS-formation, whereas the uncoupling agent carbonyl cyanide m-chlorophenyl hydrazine was without effect. Cellular Ca(2+) homeostasis was not disturbed by Cr(VI) and thus played no role in this scenario. Overall, our data show that Cr(VI) is acutely toxic to goldfish hepatocytes, and its toxicity is associated with the induction of radical stress, presumably involving lysosomes and mitochondria as important sources of ROS formation.","Acute toxicity of hexavalent chromium in isolated teleost hepatocytes Abs: Acute toxic effects of hexavalent chromium [Cr(VI)], a widely recognised carcinogenic, mutagenic and redox active metal, were investigated in isolated hepatocytes of goldfish (Carassius auratus). Exposure to 250 microM Cr(VI) induced a significant decrease of cell viability from 94% in controls to 88% and 84% after 30 min and 4 h of exposure, respectively. Cr-toxicity was associated with a concentration-dependent stimulation of the formation of reactive oxygen species (ROS). As one potential source of ROS formation we identified the lysosomal Fe(2+) pool, since the ferric ion chelator deferoxamin inhibited ROS formation by approximately 15%. Lysosomal membranes remained nevertheless intact during Cr-exposure, as determined from neutral red retention in this compartment. Another significant source of ROS appear to be the mitochondria, where a presumably uncoupled increase of respiration by 20-30% was triggered by the metal. Inhibition of mitochondrial respiration by cyanide caused an approximately 40% decrease of Cr-induced ROS-formation, whereas the uncoupling agent carbonyl cyanide m-chlorophenyl hydrazine was without effect. Cellular Ca(2+) homeostasis was not disturbed by Cr(VI) and thus played no role in this scenario. Overall, our data show that Cr(VI) is acutely toxic to goldfish hepatocytes, and its toxicity is associated with the induction of radical stress, presumably involving lysosomes and mitochondria as important sources of ROS formation."
1231939,Hazelwood et al. 2004,Field method for the determination of insoluble or total hexavalent chromium in workplace air,"National Institute for Occupational Safety and Health method 7703 is a portable field procedure for the analysis of workplace air filter samples for hexavalent chromium (CrVI) content immediately after the samples are collected. The field method prescribes CrVI extraction from air filter samples with an ammonium sulfate/ammonium hydroxide extraction buffer using ultrasonic extraction (UE). Strong anion-exchange solid-phase extraction (SAE-SPE) is then used to separate CrVI from trivalent chromium and other interferences. Portable spectrophotometric measurement of CrVI is then conducted using the 1,5-diphenylcarbazide (DPC) method. However, it has been found that the ammonium extraction buffer does not adequately bring insoluble CrVI compounds into solution during the UE process. Thus, it was deemed necessary to modify the field method so that it would provide acceptable recoveries for insoluble CrVI compounds. To this end, a more alkaline extraction solution--sodium carbonate/sodium bicarbonate buffer--was investigated. The modified procedure using the highly alkaline extraction solution was demonstrated to be compatible with SAE-SPE cartridges when determining insoluble CrVI in air filter samples. It was found that the carbonate/bicarbonate buffer was equally effective for complete dissolution of both insoluble and soluble forms of CrVI. Furthermore, the modified procedure met desired performance criteria established for air sampling and analytical methods.","Field method for the determination of insoluble or total hexavalent chromium in workplace air Abs: National Institute for Occupational Safety and Health method 7703 is a portable field procedure for the analysis of workplace air filter samples for hexavalent chromium (CrVI) content immediately after the samples are collected. The field method prescribes CrVI extraction from air filter samples with an ammonium sulfate/ammonium hydroxide extraction buffer using ultrasonic extraction (UE). Strong anion-exchange solid-phase extraction (SAE-SPE) is then used to separate CrVI from trivalent chromium and other interferences. Portable spectrophotometric measurement of CrVI is then conducted using the 1,5-diphenylcarbazide (DPC) method. However, it has been found that the ammonium extraction buffer does not adequately bring insoluble CrVI compounds into solution during the UE process. Thus, it was deemed necessary to modify the field method so that it would provide acceptable recoveries for insoluble CrVI compounds. To this end, a more alkaline extraction solution--sodium carbonate/sodium bicarbonate buffer--was investigated. The modified procedure using the highly alkaline extraction solution was demonstrated to be compatible with SAE-SPE cartridges when determining insoluble CrVI in air filter samples. It was found that the carbonate/bicarbonate buffer was equally effective for complete dissolution of both insoluble and soluble forms of CrVI. Furthermore, the modified procedure met desired performance criteria established for air sampling and analytical methods."
1231936,Ochola and  Moo-Young 2004,Establishing and elucidating reduction as the removal mechanism of Cr(VI) by reclaimed limestone residual RLR (Modified Steel Slag),"The viability of utilizing Reclaimed Limestone Residual RLR (Modified Steel Slag) to remove hexavalent chromium Cr(VI) from the aqueous phase was investigated. A physical characterization of RLR showed that it is composed of various minerals some of which can reduce and others adsorb Cr(VI). Preliminary results showed that RLR significantly reduced the concentration of Cr(VI) from the aqueous phase. Adsorption competition tests with orthophosphate (HP04(2-)) and sulfate (SO4(2-)) showed that Cr(VI) was still effectively reduced from solution regardless of the competing anions present. Kinetic tests based on the relationship d[Cr(VI)]/dt = kCr[RLR]alpha[Cr(VI)]beta showed that under initially neutral to basic conditions kCr = 3.45+/-(0.25) x 10(-4) mg0.4 L(-0.4) h(-1), alpha = 0.9, and beta = -0.3, while under initially acidic conditions kCr = 5.65+/-(1.055) x 10(-1) mg(-0.4) L0.4 h(-1), alpha = 2.2, and beta = -0.8. Stirred batch tests with RLR in deionized water showed significant drops in the redox potential (Eh), and in the presence of oxygen Eh values dropped to between 50 and 100 mV while in the absence of oxygen Eh values as low as -200 mV were observed. These results lead to the conclusion that redox mechanisms were responsible for the reduction of hexavalent chromium by RLR.","Establishing and elucidating reduction as the removal mechanism of Cr(VI) by reclaimed limestone residual RLR (Modified Steel Slag) Abs: The viability of utilizing Reclaimed Limestone Residual RLR (Modified Steel Slag) to remove hexavalent chromium Cr(VI) from the aqueous phase was investigated. A physical characterization of RLR showed that it is composed of various minerals some of which can reduce and others adsorb Cr(VI). Preliminary results showed that RLR significantly reduced the concentration of Cr(VI) from the aqueous phase. Adsorption competition tests with orthophosphate (HP04(2-)) and sulfate (SO4(2-)) showed that Cr(VI) was still effectively reduced from solution regardless of the competing anions present. Kinetic tests based on the relationship d[Cr(VI)]/dt = kCr[RLR]alpha[Cr(VI)]beta showed that under initially neutral to basic conditions kCr = 3.45+/-(0.25) x 10(-4) mg0.4 L(-0.4) h(-1), alpha = 0.9, and beta = -0.3, while under initially acidic conditions kCr = 5.65+/-(1.055) x 10(-1) mg(-0.4) L0.4 h(-1), alpha = 2.2, and beta = -0.8. Stirred batch tests with RLR in deionized water showed significant drops in the redox potential (Eh), and in the presence of oxygen Eh values dropped to between 50 and 100 mV while in the absence of oxygen Eh values as low as -200 mV were observed. These results lead to the conclusion that redox mechanisms were responsible for the reduction of hexavalent chromium by RLR."
1231935,He et al. 2004,Inhibited Cr(VI) reduction by aqueous Fe(II) under hyperalkaline conditions,"This study investigated Cr(VI) reduction by dissolved Fe(II) in hyperalkaline pH conditions as found in fluid wastes associated with the U.S. nuclear weapons program. The results show that Cr(VI) reduction by Fe(II) at alkaline pH solutions proceeds very quickly. The amount of Cr(VI) removed from solution and the amount reduced increases with Fe(II):Cr(VI) ratio. However, the Cr(VI) reduction under alkaline pH condition is nonstoichiometric, probably due to Fe(II) precipitation and mixed iron(III)-chromium-(III) (oxy)hydroxides blocking Fe(II) surface sites, as well as removing Fe(II) from solution through O2 oxidation. After Cr(VI) was reduced to Cr(III), it precipitated out as mixed Fe(x)Cr1-xO3(solids) and various Fe(III) precipitates with an overall Cr:Fe ratio of 1:3; all Cr remaining in the solution phase was unreduced Cr(VI). EXAFS data showed that Cr-O and Cr-Cr distances in the precipitates equal to 1.98 and 3.01 A, respectively, consistent with the spinel-type structure as chromite.","Inhibited Cr(VI) reduction by aqueous Fe(II) under hyperalkaline conditions Abs: This study investigated Cr(VI) reduction by dissolved Fe(II) in hyperalkaline pH conditions as found in fluid wastes associated with the U.S. nuclear weapons program. The results show that Cr(VI) reduction by Fe(II) at alkaline pH solutions proceeds very quickly. The amount of Cr(VI) removed from solution and the amount reduced increases with Fe(II):Cr(VI) ratio. However, the Cr(VI) reduction under alkaline pH condition is nonstoichiometric, probably due to Fe(II) precipitation and mixed iron(III)-chromium-(III) (oxy)hydroxides blocking Fe(II) surface sites, as well as removing Fe(II) from solution through O2 oxidation. After Cr(VI) was reduced to Cr(III), it precipitated out as mixed Fe(x)Cr1-xO3(solids) and various Fe(III) precipitates with an overall Cr:Fe ratio of 1:3; all Cr remaining in the solution phase was unreduced Cr(VI). EXAFS data showed that Cr-O and Cr-Cr distances in the precipitates equal to 1.98 and 3.01 A, respectively, consistent with the spinel-type structure as chromite."
1231934,Prasad and  Singh 2004,Reactions of sulphur mustard on impregnated carbons,"Activated carbon of surface area 1100 m2/gm is impregnated with 4% sodium hydroxide plus 3% Cr(VI) as CrO3 with and without 5% ethylene diamine (EDA), 4% magnesium nitrate and 5% ruthenium chloride by using their aqueous solutions. These carbons are characterized for surface area analysis by BET conventional method and exposed to the vapours of sulphur mustard (HD) at room temperature (30 degrees C). After 24 h, the reaction products are extracted in dichloromethane and analyzed using gas chromatography and mass spectrometry (GC-MS). Hemisulphur mustard, thiodiglycol, 1,4-oxathiane are observed to be the products of reaction between sulphur mustard and NaOH/CrO3/C system, whereas on NaOH/CrO3/EDA/C system HD reacted to give 1,4-thiazane. On Mg(NO3)2/C system it gave hemisulphur mustard and thiodiglycol. On RuCl3/C system it degraded to divinyl sulphone. Residual sulphur mustard is observed along with reaction products in all systems studied. Reaction mechanisms are also proposed for these interesting surface reactions. Above-mentioned carbons can be used in filtration systems for protection against hazardous gases such as sulphur mustard.","Reactions of sulphur mustard on impregnated carbons Abs: Activated carbon of surface area 1100 m2/gm is impregnated with 4% sodium hydroxide plus 3% Cr(VI) as CrO3 with and without 5% ethylene diamine (EDA), 4% magnesium nitrate and 5% ruthenium chloride by using their aqueous solutions. These carbons are characterized for surface area analysis by BET conventional method and exposed to the vapours of sulphur mustard (HD) at room temperature (30 degrees C). After 24 h, the reaction products are extracted in dichloromethane and analyzed using gas chromatography and mass spectrometry (GC-MS). Hemisulphur mustard, thiodiglycol, 1,4-oxathiane are observed to be the products of reaction between sulphur mustard and NaOH/CrO3/C system, whereas on NaOH/CrO3/EDA/C system HD reacted to give 1,4-thiazane. On Mg(NO3)2/C system it gave hemisulphur mustard and thiodiglycol. On RuCl3/C system it degraded to divinyl sulphone. Residual sulphur mustard is observed along with reaction products in all systems studied. Reaction mechanisms are also proposed for these interesting surface reactions. Above-mentioned carbons can be used in filtration systems for protection against hazardous gases such as sulphur mustard."
1231933,Humphries et al. 2004,Continuous removal of Cr(VI) from aqueous solution catalysed by palladised biomass of Desulfovibrio vulgaris,"Growth-decoupled cells of Desulfovibrio vulgaris NCIMB 8303 can be used to reduce Pd(II) to cell-bound Pd(0) (Bio-Pd(0)), a bioinorganic catalyst capable of reducing hexavalent chromium to less toxic Cr(III), using formate as the electron donor. Magnetic resonance imaging showed that Bio-Pd(0), immobilized in chitosan and agar beads, is distinguishable from the surrounding gel and is evenly dispersed within the immobilization matrix. Agar-immobilized Bio-Pd(0) and 'chemical Pd(0)' were packed into continuous-flow reactors, and challenged with a solution containing 100 microM Cr(VI) (pH 7) at a flow rate of 2.4 ml h(-1). Agar-immobilized chemical Pd(0) columns lost Cr(VI) reducing ability by 160 h, whereas columns containing immobilized Bio-Pd(0) maintained 90% reduction until 680 h, after which reduction efficiency was gradually lost.","Continuous removal of Cr(VI) from aqueous solution catalysed by palladised biomass of Desulfovibrio vulgaris Abs: Growth-decoupled cells of Desulfovibrio vulgaris NCIMB 8303 can be used to reduce Pd(II) to cell-bound Pd(0) (Bio-Pd(0)), a bioinorganic catalyst capable of reducing hexavalent chromium to less toxic Cr(III), using formate as the electron donor. Magnetic resonance imaging showed that Bio-Pd(0), immobilized in chitosan and agar beads, is distinguishable from the surrounding gel and is evenly dispersed within the immobilization matrix. Agar-immobilized Bio-Pd(0) and 'chemical Pd(0)' were packed into continuous-flow reactors, and challenged with a solution containing 100 microM Cr(VI) (pH 7) at a flow rate of 2.4 ml h(-1). Agar-immobilized chemical Pd(0) columns lost Cr(VI) reducing ability by 160 h, whereas columns containing immobilized Bio-Pd(0) maintained 90% reduction until 680 h, after which reduction efficiency was gradually lost."
1231932,Morais et al. 2004,"Leucobacter chromiireducens sp. nov, and Leucobacter aridicollis sp. nov., two new species isolated from a chromium contaminated environment","Two strains designated strains L-1T and L-9T were isolated from activated sludge of a treatment plant that receives wastewater from the tannery industry contaminated with chromium. Phylogenetic analysis showed that the organisms represented two new species of the genus Leucobacter. Strains L-1T and L-9T could be distinguished from the type strain of L. komagatae and from the type strain of &quot;L. albus&quot; by the B-type peptidoglycan composition, fatty acid composition, several phenotypic and physiological characteristics. The major fatty acids of the organisms were iso- and anteiso-branched C15:0 and C17:0, straight-chain C16:0 was also found in relatively high proportions. The organisms were halotolerant, grew in medium containing 9% NaCl, and all strains, including the type strain of L. komagatae grew in medium containing 5 mM Cr(VI). On the basis of the distinct peptidoglycan composition, 16S ribosomal DNA sequence analysis, percentage of DNA-DNA reassociation values, and phenotypic characteristics we are of the opinion that strain L-1T represents a new species of the genus Leucobacter for which we propose the name Leucobacter chromiireducens and that strain L-9T represents an additional new species of the same genus for which we propose the name Leucobacter aridicollis.","Leucobacter chromiireducens sp. nov, and Leucobacter aridicollis sp. nov., two new species isolated from a chromium contaminated environment Abs: Two strains designated strains L-1T and L-9T were isolated from activated sludge of a treatment plant that receives wastewater from the tannery industry contaminated with chromium. Phylogenetic analysis showed that the organisms represented two new species of the genus Leucobacter. Strains L-1T and L-9T could be distinguished from the type strain of L. komagatae and from the type strain of &quot;L. albus&quot; by the B-type peptidoglycan composition, fatty acid composition, several phenotypic and physiological characteristics. The major fatty acids of the organisms were iso- and anteiso-branched C15:0 and C17:0, straight-chain C16:0 was also found in relatively high proportions. The organisms were halotolerant, grew in medium containing 9% NaCl, and all strains, including the type strain of L. komagatae grew in medium containing 5 mM Cr(VI). On the basis of the distinct peptidoglycan composition, 16S ribosomal DNA sequence analysis, percentage of DNA-DNA reassociation values, and phenotypic characteristics we are of the opinion that strain L-1T represents a new species of the genus Leucobacter for which we propose the name Leucobacter chromiireducens and that strain L-9T represents an additional new species of the same genus for which we propose the name Leucobacter aridicollis."
1231931,Altundogan et al. 2004,A study on the reduction of hexavalent chromium in aqueous solutions by vinasse,"Hexavalent chromium introduced to the water ecosystem is an important issue due to the toxic effect it poses. The first step of conventional treatment of wastewaters containing hexavalent chromium is its reduction to chromium (III) which is less toxic. The use of industrial waste material for the reduction of chromium (VI) may be a new cost-effective alternative. In this study, Cr(VI) reduction characteristics of vinasse which is a waste material of alcohol production from sugar beet molasses was investigated. The parameters of pH, temperature, concentrations of initial Cr(VI) and vinasse on the reduction of Cr(VI) were examined as a function of time by applying batch tests. Cr(VI) was almost completely reduced within about 270 min in the concentrations of Cr(VI) and vinasse of 80 mg l(-1) and 200 ml l(-1), respectively, at pH 3.0 and 25 degrees C. The results showed that reduction time can be shortened by increasing acidity and vinasse concentration or decreasing Cr(VI) initial concentration. Cr(VI) reduction process was found be obey first order kinetic model of homogenous phase reactions. The temperature was found to have a positive effect on the reduction process and the activation energy of process was calculated as 46.07 kJ mol(-1). Although the detoxification of wastewaters containing Cr(VI) via reducing it to Cr(III) by using vinasse seems to be cost-effective, the resulting effluent to be produced necessitates a further treatment to reduce organic pollution.","A study on the reduction of hexavalent chromium in aqueous solutions by vinasse Abs: Hexavalent chromium introduced to the water ecosystem is an important issue due to the toxic effect it poses. The first step of conventional treatment of wastewaters containing hexavalent chromium is its reduction to chromium (III) which is less toxic. The use of industrial waste material for the reduction of chromium (VI) may be a new cost-effective alternative. In this study, Cr(VI) reduction characteristics of vinasse which is a waste material of alcohol production from sugar beet molasses was investigated. The parameters of pH, temperature, concentrations of initial Cr(VI) and vinasse on the reduction of Cr(VI) were examined as a function of time by applying batch tests. Cr(VI) was almost completely reduced within about 270 min in the concentrations of Cr(VI) and vinasse of 80 mg l(-1) and 200 ml l(-1), respectively, at pH 3.0 and 25 degrees C. The results showed that reduction time can be shortened by increasing acidity and vinasse concentration or decreasing Cr(VI) initial concentration. Cr(VI) reduction process was found be obey first order kinetic model of homogenous phase reactions. The temperature was found to have a positive effect on the reduction process and the activation energy of process was calculated as 46.07 kJ mol(-1). Although the detoxification of wastewaters containing Cr(VI) via reducing it to Cr(III) by using vinasse seems to be cost-effective, the resulting effluent to be produced necessitates a further treatment to reduce organic pollution."
1231930,Bo?gelmez and  Güvendik 2004,Effects of taurine on oxidative stress parameters and chromium levels altered by acute hexavalent chromium exposure in mice kidney tissue,"The kidney has been regarded as a critical organ of toxicity induced by acute exposure to hexavalent chromium [Cr(VI)] compounds. Reactive intermediates and free radicals generated during reduction process might be responsible for Cr(VI) toxicity. In this study, the effects of pretreatment or posttreatment of taurine on Cr(VI)-induced oxidative stress and chromium accumulation in kidney tissue of Swiss albino mice were investigated. Single intraperitoneal (ip) potassium dichromate treatment (20 mgCr/kg), as Cr(VI) compound, significantly elevated the level of lipid peroxidation as compared with the control group (p&lt;0.05). This was accompanied by significant decreases in nonprotein sulfhydryls (NPSH) level, superoxide dismutase (SOD), and catalase (CAT) enzyme activities as well as a significant chromium accumulation (p&lt;0.05). Taurine administration (1 g/kg, ip) before or after Cr(VI) exposure resulted in reduction of lipid peroxidation levels and improvement in SOD enzyme activity (p&lt;0.05). On the other hand, administration of the antioxidant before Cr(VI) exposure restored the NPSH level and CAT enzyme activity and also reduced tissue chromium levels (p&lt;0.05), whereas posttreatment had only slight effects on these parameters. In view of the results, taurine seems to exert some beneficial effects against Cr(VI)-induced oxidative stress and chromium accumulation in mice kidney tissue.","Effects of taurine on oxidative stress parameters and chromium levels altered by acute hexavalent chromium exposure in mice kidney tissue Abs: The kidney has been regarded as a critical organ of toxicity induced by acute exposure to hexavalent chromium [Cr(VI)] compounds. Reactive intermediates and free radicals generated during reduction process might be responsible for Cr(VI) toxicity. In this study, the effects of pretreatment or posttreatment of taurine on Cr(VI)-induced oxidative stress and chromium accumulation in kidney tissue of Swiss albino mice were investigated. Single intraperitoneal (ip) potassium dichromate treatment (20 mgCr/kg), as Cr(VI) compound, significantly elevated the level of lipid peroxidation as compared with the control group (p&lt;0.05). This was accompanied by significant decreases in nonprotein sulfhydryls (NPSH) level, superoxide dismutase (SOD), and catalase (CAT) enzyme activities as well as a significant chromium accumulation (p&lt;0.05). Taurine administration (1 g/kg, ip) before or after Cr(VI) exposure resulted in reduction of lipid peroxidation levels and improvement in SOD enzyme activity (p&lt;0.05). On the other hand, administration of the antioxidant before Cr(VI) exposure restored the NPSH level and CAT enzyme activity and also reduced tissue chromium levels (p&lt;0.05), whereas posttreatment had only slight effects on these parameters. In view of the results, taurine seems to exert some beneficial effects against Cr(VI)-induced oxidative stress and chromium accumulation in mice kidney tissue."
1231927,Berry et al. 2004,Predicting the toxicity of chromium in sediments,"Chromium exists in sediments in two oxidation states: Cr(III), which is relatively insoluble and nontoxic, and Cr(VI), which is much more soluble and toxic. Chromium(VI) is thermodynamically unstable in anoxic sediments, and acid-volatile sulfide (AVS) is formed only in anoxic sediments; therefore sediments with measurable AVS concentrations should not contain toxic Cr(VI). If this hypothesis holds true, measuring AVS could form the basis for a theoretically based guideline for Cr in sediments. Ten-day water-only and spiked sediment toxicity tests with the amphipod Ampelisca abdita were performed with Cr(VI) and Cr(III), along with sediments collected from a site contaminated with high concentrations of Cr. In sediments where AVS exceeded analytical detection limits, Cr concentrations in interstitial water were very low (&lt;100 microg/L) and no significant toxicity to A. abdita was observed. In sediments in which AVS was not significantly greater than zero, Cr concentrations in interstitial waters increased significantly, with greater than 90% of the Cr present as Cr(VI), and mortality of A. abdita was elevated. These results demonstrate that measurements of AVS and interstitial water chromium can be useful in predicting the absence of acute effects from Cr contamination in sediments.","Predicting the toxicity of chromium in sediments Abs: Chromium exists in sediments in two oxidation states: Cr(III), which is relatively insoluble and nontoxic, and Cr(VI), which is much more soluble and toxic. Chromium(VI) is thermodynamically unstable in anoxic sediments, and acid-volatile sulfide (AVS) is formed only in anoxic sediments; therefore sediments with measurable AVS concentrations should not contain toxic Cr(VI). If this hypothesis holds true, measuring AVS could form the basis for a theoretically based guideline for Cr in sediments. Ten-day water-only and spiked sediment toxicity tests with the amphipod Ampelisca abdita were performed with Cr(VI) and Cr(III), along with sediments collected from a site contaminated with high concentrations of Cr. In sediments where AVS exceeded analytical detection limits, Cr concentrations in interstitial water were very low (&lt;100 microg/L) and no significant toxicity to A. abdita was observed. In sediments in which AVS was not significantly greater than zero, Cr concentrations in interstitial waters increased significantly, with greater than 90% of the Cr present as Cr(VI), and mortality of A. abdita was elevated. These results demonstrate that measurements of AVS and interstitial water chromium can be useful in predicting the absence of acute effects from Cr contamination in sediments."
1231926,Sun et al. 2005,Characterization of adsorbent composition in co-removal of hexavalent chromium with copper precipitation,"Mechanisms of hexavalent chromium co-removal with copper precipitation by dosing Na2CO3 were studied with a series of well-designed batch tests using solutions containing 150 mg l-1 Cu(II) and 60 mg l-1 Cr(VI). It was found that direct precipitation of chromium through formation of copper-chromium bearing precipitates (in the form of CuCrO4) was one of the main mechanisms contributing to chromium co-removal at pH close to 5.0, and adsorption of chromium at a higher pH by freshly formed copper-carbonate precipitates (adsorbent) contributed to further chromium co-removal. Since, according to solubility products, neither copper-carbonate nor copper-hydroxide precipitates can be produced at pH around 5.0 for a pure 150 mg l-1 copper precipitation, characterization of copper-carbonate precipitates (adsorbent) was carried out through developing pC-pH curves of the systems by both equilibrium calculations and MINEQL+ 4.5 (a chemical equilibrium modeling software), and also through laboratory determination of the precipitate composition, such as gravimetric analyses, inorganic carbon percentage and EDAX spectrum analyses. CuCO3.Cu(OH)2, or a combination of CuCO3.Cu(OH)2 (in majority) and Cu(OH)2 (in minority) were suggested to be the major constituent of the precipitates obtained from the copper solution with Na2CO3 dosing.","Characterization of adsorbent composition in co-removal of hexavalent chromium with copper precipitation Abs: Mechanisms of hexavalent chromium co-removal with copper precipitation by dosing Na2CO3 were studied with a series of well-designed batch tests using solutions containing 150 mg l-1 Cu(II) and 60 mg l-1 Cr(VI). It was found that direct precipitation of chromium through formation of copper-chromium bearing precipitates (in the form of CuCrO4) was one of the main mechanisms contributing to chromium co-removal at pH close to 5.0, and adsorption of chromium at a higher pH by freshly formed copper-carbonate precipitates (adsorbent) contributed to further chromium co-removal. Since, according to solubility products, neither copper-carbonate nor copper-hydroxide precipitates can be produced at pH around 5.0 for a pure 150 mg l-1 copper precipitation, characterization of copper-carbonate precipitates (adsorbent) was carried out through developing pC-pH curves of the systems by both equilibrium calculations and MINEQL+ 4.5 (a chemical equilibrium modeling software), and also through laboratory determination of the precipitate composition, such as gravimetric analyses, inorganic carbon percentage and EDAX spectrum analyses. CuCO3.Cu(OH)2, or a combination of CuCO3.Cu(OH)2 (in majority) and Cu(OH)2 (in minority) were suggested to be the major constituent of the precipitates obtained from the copper solution with Na2CO3 dosing."
1231925,Proctor et al. 2004,Estimating historical occupational exposure to airborne hexavalent chromium in a chromate production plant: 1940--1972,"This article presents a retrospective exposure assessment for 493 workers who were occupationally exposed to airborne hexavalent chromium, Cr(VI), at a Painesville, Ohio, chromate production plant from 1940-1972. Exposure estimates were reconstructed using a job-exposure matrix approach that related job titles with area monitoring data from 21 industrial hygiene surveys conducted from 1943 to 1971. No personal monitoring data were collected. Specifically, airborne Cr(VI) concentration profiles for 22 areas of the plant, termed job-exposure group (JEG) areas, were constructed for three distinct time periods (1940-1949, 1950-1964, and 1965-1972), with cut points based on known major plant and process changes. Average airborne Cr(VI) concentrations were the highest for the bridge crane operators (5.5 mg/m3) prior to 1965, although only four cohort members held this job title. Airborne concentrations for the rest of the production areas of the plant ranged from 1.9 mg/m3 for packers in the 1940s to 0.012 mg/m3 for ore mill operators after 1964. For nearly all JEG areas, exposures decreased over time, particularly after 1964. For example, average airborne concentrations in production areas of the plant decreased from 0.72 mg/m3 in the 1940s to 0.27 mg/m3 from 1950 to 1964, and the average was 0.039 mg/m3 after 1964. Former workers were interviewed to determine activity patterns in the plant by job title. This information was combined with Cr(VI) monitoring data to calculate cumulative occupational exposure for each worker. Cumulative exposures ranged from 0.003 to 23 (mg/m3) x years. The highest monthly 8-hour average exposure concentration for each worker ranged from 0.003 to 4.1 mg/m3. These exposure estimates have been combined with mortality data for this cohort to assess the lung cancer risk associated with inhaled Cr(VI), and a positive dose-response relationship was observed for increases in lung cancer mortality with measures of cumulative exposure and highest monthly exposure.","Estimating historical occupational exposure to airborne hexavalent chromium in a chromate production plant: 1940--1972 Abs: This article presents a retrospective exposure assessment for 493 workers who were occupationally exposed to airborne hexavalent chromium, Cr(VI), at a Painesville, Ohio, chromate production plant from 1940-1972. Exposure estimates were reconstructed using a job-exposure matrix approach that related job titles with area monitoring data from 21 industrial hygiene surveys conducted from 1943 to 1971. No personal monitoring data were collected. Specifically, airborne Cr(VI) concentration profiles for 22 areas of the plant, termed job-exposure group (JEG) areas, were constructed for three distinct time periods (1940-1949, 1950-1964, and 1965-1972), with cut points based on known major plant and process changes. Average airborne Cr(VI) concentrations were the highest for the bridge crane operators (5.5 mg/m3) prior to 1965, although only four cohort members held this job title. Airborne concentrations for the rest of the production areas of the plant ranged from 1.9 mg/m3 for packers in the 1940s to 0.012 mg/m3 for ore mill operators after 1964. For nearly all JEG areas, exposures decreased over time, particularly after 1964. For example, average airborne concentrations in production areas of the plant decreased from 0.72 mg/m3 in the 1940s to 0.27 mg/m3 from 1950 to 1964, and the average was 0.039 mg/m3 after 1964. Former workers were interviewed to determine activity patterns in the plant by job title. This information was combined with Cr(VI) monitoring data to calculate cumulative occupational exposure for each worker. Cumulative exposures ranged from 0.003 to 23 (mg/m3) x years. The highest monthly 8-hour average exposure concentration for each worker ranged from 0.003 to 4.1 mg/m3. These exposure estimates have been combined with mortality data for this cohort to assess the lung cancer risk associated with inhaled Cr(VI), and a positive dose-response relationship was observed for increases in lung cancer mortality with measures of cumulative exposure and highest monthly exposure."
1231924,Hu et al. 2004,Removal of Cr(VI) by magnetite nanoparticle,Magnetite nanoparticles were synthesized by sol-gel method. The highly crystalline nature of the magnetite structure with diameter of around 10 nm was characterized with transmission electron microscopy and X-ray diffractometry. The surface area was determined to be 198 m2/g. Batch experiments were carried out to determine the adsorption kinetics and mechanism of Cr(VI) by these magnetite nanoparticles. The Cr(VI) uptake was mainly governed by physico-chemical adsorption. The adsorption process was found to be pH and temperature dependent. The adsorption data fit well with the Freundlich isotherm equation. The Freundlich constants were calculated at different temperatures. The adsorption capacity increased with rising temperature. Preliminary results indicate that magnetite nanoparticles may be used as an adsorbent for removal of Cr(VI) from wastewater.,Removal of Cr(VI) by magnetite nanoparticle Abs: Magnetite nanoparticles were synthesized by sol-gel method. The highly crystalline nature of the magnetite structure with diameter of around 10 nm was characterized with transmission electron microscopy and X-ray diffractometry. The surface area was determined to be 198 m2/g. Batch experiments were carried out to determine the adsorption kinetics and mechanism of Cr(VI) by these magnetite nanoparticles. The Cr(VI) uptake was mainly governed by physico-chemical adsorption. The adsorption process was found to be pH and temperature dependent. The adsorption data fit well with the Freundlich isotherm equation. The Freundlich constants were calculated at different temperatures. The adsorption capacity increased with rising temperature. Preliminary results indicate that magnetite nanoparticles may be used as an adsorbent for removal of Cr(VI) from wastewater.
1231923,Gardea-Torresdey et al. 2005,Differential uptake and transport of trivalent and hexavalent chromium by tumbleweed (Salsola kali),"Experiments were conducted to determine the differential absorption of Cr species by tumbleweed (Salsola kali) as well as the effect of this heavy metal on plant growth and nutrient uptake. Tumbleweed seeds were grown in an agar-based media containing different concentrations of either Cr(III) or Cr(VI). The results demonstrated that the uptake of Cr was influenced by the Cr concentration in the growth medium and the speciation of this heavy metal. When supplied in the hexavalent form, the concentration of Cr in the different plant parts (2900, 790, and 600 mg kg(-1) for roots, stems, and leaves, respectively) was between 10 and 20 times higher than the amounts found when Cr was supplied in the trivalent form. In addition, it was found that in most of the experiments, Cr(III) exhibited more toxic effects on tumbleweed plants than Cr(VI). The size of roots of plants grown in 20 mg L(-1) Cr(III) were significantly smaller (p &lt; 0.05) than those grown in 20 mg L(-1) Cr(VI). Plants exposed to 20 mg L(-1) Cr(III) produced shoots significantly shorter (p &lt; 0.05) compared with the size of control plants and with those grown in 20 mg L(-1) Cr(VI). In addition, the absorption of macronutrients and microelements was in general lower when the plants were grown in the medium containing Cr(III). The amounts of Cr concentrated in the aerial plant parts under experimental conditions may indicate tumbleweed as a new option for the phytoremediation of Cr-contaminated soil.","Differential uptake and transport of trivalent and hexavalent chromium by tumbleweed (Salsola kali) Abs: Experiments were conducted to determine the differential absorption of Cr species by tumbleweed (Salsola kali) as well as the effect of this heavy metal on plant growth and nutrient uptake. Tumbleweed seeds were grown in an agar-based media containing different concentrations of either Cr(III) or Cr(VI). The results demonstrated that the uptake of Cr was influenced by the Cr concentration in the growth medium and the speciation of this heavy metal. When supplied in the hexavalent form, the concentration of Cr in the different plant parts (2900, 790, and 600 mg kg(-1) for roots, stems, and leaves, respectively) was between 10 and 20 times higher than the amounts found when Cr was supplied in the trivalent form. In addition, it was found that in most of the experiments, Cr(III) exhibited more toxic effects on tumbleweed plants than Cr(VI). The size of roots of plants grown in 20 mg L(-1) Cr(III) were significantly smaller (p &lt; 0.05) than those grown in 20 mg L(-1) Cr(VI). Plants exposed to 20 mg L(-1) Cr(III) produced shoots significantly shorter (p &lt; 0.05) compared with the size of control plants and with those grown in 20 mg L(-1) Cr(VI). In addition, the absorption of macronutrients and microelements was in general lower when the plants were grown in the medium containing Cr(III). The amounts of Cr concentrated in the aerial plant parts under experimental conditions may indicate tumbleweed as a new option for the phytoremediation of Cr-contaminated soil."
1231922,Park et al. 2005,Mechanism of hexavalent chromium removal by dead fungal biomass of Aspergillus niger,"When synthetic wastewater containing Cr(VI) was placed in contact with the dead fungal biomass of Aspergillus niger, the Cr(VI) was completely removed from aqueous solution, whereas Cr(III), which was not initially present, appeared in aqueous solution. Desorption and X-ray photoelectron spectroscopy (XPS) studies showed that most of the Cr bound on the biomass was in trivalent form. These results indicated that the main mechanism of Cr(VI) removal was a redox reaction between Cr(VI) and the dead fungal biomass, which is quite different from previously reported mechanisms. The influences of contact time, pH, Cr(VI) concentration, biomass concentration and temperature on Cr(VI) removal were also evaluated. The Cr(VI) removal rate increased with a decrease in pH and with increases in Cr(VI) concentration, biomass concentration and temperature. Although removal kinetics was dependent on the experimental conditions, Cr(VI) was completely removed in the aqueous solution. In conclusion, a new mechanism of Cr(VI) removal by the dead fungal biomass has been proposed. From a practical viewpoint, this abundant and inexpensive dead fungal biomass has potential application in the conversion of toxic Cr(VI) into less toxic or nontoxic Cr(III).","Mechanism of hexavalent chromium removal by dead fungal biomass of Aspergillus niger Abs: When synthetic wastewater containing Cr(VI) was placed in contact with the dead fungal biomass of Aspergillus niger, the Cr(VI) was completely removed from aqueous solution, whereas Cr(III), which was not initially present, appeared in aqueous solution. Desorption and X-ray photoelectron spectroscopy (XPS) studies showed that most of the Cr bound on the biomass was in trivalent form. These results indicated that the main mechanism of Cr(VI) removal was a redox reaction between Cr(VI) and the dead fungal biomass, which is quite different from previously reported mechanisms. The influences of contact time, pH, Cr(VI) concentration, biomass concentration and temperature on Cr(VI) removal were also evaluated. The Cr(VI) removal rate increased with a decrease in pH and with increases in Cr(VI) concentration, biomass concentration and temperature. Although removal kinetics was dependent on the experimental conditions, Cr(VI) was completely removed in the aqueous solution. In conclusion, a new mechanism of Cr(VI) removal by the dead fungal biomass has been proposed. From a practical viewpoint, this abundant and inexpensive dead fungal biomass has potential application in the conversion of toxic Cr(VI) into less toxic or nontoxic Cr(III)."
1231919,Cavas et al. 2005,"Induction of micronuclei and binuclei in blood, gill and liver cells of fishes subchronically exposed to cadmium chloride and copper sulphate","Common carp (Cyprinus carpio), Prussian carp (Carassius gibelio) and Peppered cory (Corydoras paleatus) were evaluated as target species to perform genotoxicity tests for heavy metals. Fishes were exposed to different doses of cadmium (0.005-0.1 mg/L) and copper (0.01-0.25 mg/L) for 21 days. Hexavalent chromium at a single dose of 5 mg/L was used as a positive control. Frequencies of micronuclei and binuclei were evaluated comparatively in peripheral blood erythrocytes, gill epithelial cells and liver cells. As a result it was observed that, fish species and their tissues showed differential sensitivity to the heavy metal treatment. In general, frequencies of micronucleated and binucleated cells significantly increased following the exposure for 21 days to copper, cadmium and chromium. On the other hand, gill and liver cells showed higher frequencies of micronuclei and binuclei than erythrocytes. Our results indicated the formation of micronuclei and binuclei in fish cells caused by their exposure to cadmium, copper and chromium, thus verifying results obtained earlier on mammals, which indicated that these heavy metals have cytotoxic and genotoxic effects. The suitability of the micronucleus assay in native fish species for the screening of aquatic genotoxicants is highlighted and the importance of target tissue selection in the piscine micronucleus test is emphasized.","Induction of micronuclei and binuclei in blood, gill and liver cells of fishes subchronically exposed to cadmium chloride and copper sulphate Abs: Common carp (Cyprinus carpio), Prussian carp (Carassius gibelio) and Peppered cory (Corydoras paleatus) were evaluated as target species to perform genotoxicity tests for heavy metals. Fishes were exposed to different doses of cadmium (0.005-0.1 mg/L) and copper (0.01-0.25 mg/L) for 21 days. Hexavalent chromium at a single dose of 5 mg/L was used as a positive control. Frequencies of micronuclei and binuclei were evaluated comparatively in peripheral blood erythrocytes, gill epithelial cells and liver cells. As a result it was observed that, fish species and their tissues showed differential sensitivity to the heavy metal treatment. In general, frequencies of micronucleated and binucleated cells significantly increased following the exposure for 21 days to copper, cadmium and chromium. On the other hand, gill and liver cells showed higher frequencies of micronuclei and binuclei than erythrocytes. Our results indicated the formation of micronuclei and binuclei in fish cells caused by their exposure to cadmium, copper and chromium, thus verifying results obtained earlier on mammals, which indicated that these heavy metals have cytotoxic and genotoxic effects. The suitability of the micronucleus assay in native fish species for the screening of aquatic genotoxicants is highlighted and the importance of target tissue selection in the piscine micronucleus test is emphasized."
1231917,Carré et al. 2005,Potential of laser ablation and laser desorption mass spectrometry to characterize organic and inorganic environmental pollutants on dust particles,"Stainless steel factories are known to release particles into the atmosphere. Such particulate matter contains significant amounts of heavy metals or toxic inorganic compounds and organic pollutants such as, for example, Cr(VI) and polycyclic aromatic hydrocarbons (PAHs). The investigation of Cr(VI) and PAHs is often complicated by the associated matrix. Organic and inorganic pollutants present in stainless steel dust particles have been investigated with the same laser microprobe mass spectrometer according to two original methodologies. These analytical methods do not require time-consuming pretreatment (extraction, solubilization) or preconcentration steps. More specifically, experiments are conducted with a Fourier transform ion cyclotron resonance mass spectrometer coupled to an ArF (193 nm) or a tripled frequency Nd-YAG (355 nm) laser. Experiments at 355 nm allow the nature of the most frequently occurring Cr(III)/Cr(VI) compounds in dust particles to be identified. Examination of PAHs at 193 nm is assisted by the formation of pi-complexes with 7,7',8,8'-tetracyanoquinodimethane to prevent their evaporation in the mass spectrometer during analysis and to ensure an increase in sensitivity.","Potential of laser ablation and laser desorption mass spectrometry to characterize organic and inorganic environmental pollutants on dust particles Abs: Stainless steel factories are known to release particles into the atmosphere. Such particulate matter contains significant amounts of heavy metals or toxic inorganic compounds and organic pollutants such as, for example, Cr(VI) and polycyclic aromatic hydrocarbons (PAHs). The investigation of Cr(VI) and PAHs is often complicated by the associated matrix. Organic and inorganic pollutants present in stainless steel dust particles have been investigated with the same laser microprobe mass spectrometer according to two original methodologies. These analytical methods do not require time-consuming pretreatment (extraction, solubilization) or preconcentration steps. More specifically, experiments are conducted with a Fourier transform ion cyclotron resonance mass spectrometer coupled to an ArF (193 nm) or a tripled frequency Nd-YAG (355 nm) laser. Experiments at 355 nm allow the nature of the most frequently occurring Cr(III)/Cr(VI) compounds in dust particles to be identified. Examination of PAHs at 193 nm is assisted by the formation of pi-complexes with 7,7',8,8'-tetracyanoquinodimethane to prevent their evaporation in the mass spectrometer during analysis and to ensure an increase in sensitivity."
1231916,Lee et al. 2005,"Interindividual variability in response to sodium dichromate-induced oxidative DNA damage: role of the Ser326Cys polymorphism in the DNA-repair protein of 8-oxo-7,8-dihydro-2'-deoxyguanosine DNA glycosylase 1","Although the genotoxic mechanism(s) of hexavalent chromium (CrVI) carcinogenicity remain to be fully elucidated, intracellular reduction of CrVI and concomitant generation of reactive intermediates including reactive oxygen species and subsequent oxidative damage to DNA is believed to contribute to the process of carcinogenesis. In the current study, substantial interindividual variation (7.19-25.84% and 8.79-34.72% tail DNA as assessed by conventional and FPG-modified comet assay, respectively) in levels of DNA strand breaks after in vitro treatment of WBC with sodium dichromate (100 micromol/L, 1 hour) was shown within a group of healthy adult volunteers (n = 72) as assessed by both comet and formamidopyrimidine glycosylase-modified comet assays. No statistically significant correlation between glutathione S-transferases M1 or T1, NADPH quinone oxidoreductase 1 (codon 187) and X-ray repair cross complementation factor 1 (codon 194) genotypes and individual levels of DNA damage were observed. However, individuals homozygous for the Cys(326) 8-oxo 7,8-dihydro-2'-deoxyguanosine glycosylase 1 (OGG1) polymorphism had a statistically significant elevation of formamidopyrimidine glycosylase-dependent oxidative DNA damage after treatment with sodium dichromate when compared with either Ser(326)/Ser(326) or Ser(326)/Cys(326) individuals (P = 0.008 and P = 0.003, respectively). In contrast, no effect of OGG1 genotype on background levels of oxidative DNA damage was observed. When individuals were divided on the basis of OGG1 genotype, Cys(326)/Cys(326) individuals had a statistically significant (P &lt; 0.05, one-way ANOVA followed by Tukey test) higher ratio of oxidative DNA damage to plasma antioxidant capacity than either Ser(326)/Ser(326) or Ser(326)/Cys(326) individuals. The results of this study suggest that the Cys(326)/Cys(326) OGG1 genotype may represent a phenotype that is deficient in the repair of 8-oxo-7,8-dihydro-2'-deoxyguanosine, but only under conditions of cellular oxidative stress. We hypothesize that this may be due to oxidation of the Cys(326) residue. In conclusion, the homozygous Cys(326) genotype may represent a biomarker of individual susceptibility of lung cancer risk in individuals that are occupationally exposed to CrVI.","Interindividual variability in response to sodium dichromate-induced oxidative DNA damage: role of the Ser326Cys polymorphism in the DNA-repair protein of 8-oxo-7,8-dihydro-2'-deoxyguanosine DNA glycosylase 1 Abs: Although the genotoxic mechanism(s) of hexavalent chromium (CrVI) carcinogenicity remain to be fully elucidated, intracellular reduction of CrVI and concomitant generation of reactive intermediates including reactive oxygen species and subsequent oxidative damage to DNA is believed to contribute to the process of carcinogenesis. In the current study, substantial interindividual variation (7.19-25.84% and 8.79-34.72% tail DNA as assessed by conventional and FPG-modified comet assay, respectively) in levels of DNA strand breaks after in vitro treatment of WBC with sodium dichromate (100 micromol/L, 1 hour) was shown within a group of healthy adult volunteers (n = 72) as assessed by both comet and formamidopyrimidine glycosylase-modified comet assays. No statistically significant correlation between glutathione S-transferases M1 or T1, NADPH quinone oxidoreductase 1 (codon 187) and X-ray repair cross complementation factor 1 (codon 194) genotypes and individual levels of DNA damage were observed. However, individuals homozygous for the Cys(326) 8-oxo 7,8-dihydro-2'-deoxyguanosine glycosylase 1 (OGG1) polymorphism had a statistically significant elevation of formamidopyrimidine glycosylase-dependent oxidative DNA damage after treatment with sodium dichromate when compared with either Ser(326)/Ser(326) or Ser(326)/Cys(326) individuals (P = 0.008 and P = 0.003, respectively). In contrast, no effect of OGG1 genotype on background levels of oxidative DNA damage was observed. When individuals were divided on the basis of OGG1 genotype, Cys(326)/Cys(326) individuals had a statistically significant (P &lt; 0.05, one-way ANOVA followed by Tukey test) higher ratio of oxidative DNA damage to plasma antioxidant capacity than either Ser(326)/Ser(326) or Ser(326)/Cys(326) individuals. The results of this study suggest that the Cys(326)/Cys(326) OGG1 genotype may represent a phenotype that is deficient in the repair of 8-oxo-7,8-dihydro-2'-deoxyguanosine, but only under conditions of cellular oxidative stress. We hypothesize that this may be due to oxidation of the Cys(326) residue. In conclusion, the homozygous Cys(326) genotype may represent a biomarker of individual susceptibility of lung cancer risk in individuals that are occupationally exposed to CrVI."
1231915,Hellerich and  Nikolaidis 2005,Sorption studies of mixed chromium and chlorinated ethenes at the field and laboratory scales,"The sorption and desorption behavior of hexavalent chromium and chlorinated ethenes in a sandy ground water aquifer with a low reduction capacity was evaluated by performing a variety of analyses and experiments at the laboratory (batch and column studies) and field (in situ injection-withdrawal experiment) scales. The partitioning coefficients determined from the field and laboratory experiments are generally similar. Both sets of experiments yielded relatively low partition coefficients for chromium and chlorinated ethenes. The column studies and injection-withdrawal experiment indicate that chromium has the potential to leach from aquifer sediments and act as a secondary source of contamination. However, the magnitude of the secondary source effect is not significant due to low concentrations of leachable contamination. The chromium sorption isotherm data were also simulated using the triple layer surface complexation model (TLM). The isotherm data were modeled using the TLM, illustrating the applicability of geochemical modeling for sorption of chromium to these sediments under variable pE-pH conditions.","Sorption studies of mixed chromium and chlorinated ethenes at the field and laboratory scales Abs: The sorption and desorption behavior of hexavalent chromium and chlorinated ethenes in a sandy ground water aquifer with a low reduction capacity was evaluated by performing a variety of analyses and experiments at the laboratory (batch and column studies) and field (in situ injection-withdrawal experiment) scales. The partitioning coefficients determined from the field and laboratory experiments are generally similar. Both sets of experiments yielded relatively low partition coefficients for chromium and chlorinated ethenes. The column studies and injection-withdrawal experiment indicate that chromium has the potential to leach from aquifer sediments and act as a secondary source of contamination. However, the magnitude of the secondary source effect is not significant due to low concentrations of leachable contamination. The chromium sorption isotherm data were also simulated using the triple layer surface complexation model (TLM). The isotherm data were modeled using the TLM, illustrating the applicability of geochemical modeling for sorption of chromium to these sediments under variable pE-pH conditions."
1231914,Gode and  Pehlivan 2005,Removal of Cr(VI) from aqueous solution by two Lewatit-anion exchange resins,"The sorption of hexavalent chromium, Cr(VI), from aqueous solutions on macroporous resins containing tertiary amine groups (Lewatit MP 62 and Lewatit M 610) was studied at varying Cr(VI) concentrations, adsorbent dose, pH, contact time and temperatures. The concentration of chromium in aqueous solution was determined by inductively coupled plasma spectrometry (ICP-AES). Batch shaking sorption experiments were carried out to evaluate the performance of Lewatit MP 62 and Lewatit M 610 anion exchange resins in the removal of Cr(VI) from aqueous solutions. The ion-exchange process, which is pH dependent, shows maximum removal of Cr(VI) in the pH range 2-6 for an initial Cr(VI) concentration of 100 ppm. The sorption increases with the decrease in pH and slightly decreases with the increase in temperature. Both ion exchangers had high bonding constants with Lewatit M 610 showing stronger binding. It was observed that the maximum adsorption capacity of 0.40 mmol of Cr(VI)/g for Lewatit MP 62 and 0.41 mmol of Cr(VI)/g for Lewatit M 610 was achieved at pH of 5.0. The thermodynamic parameters (free energy change, DeltaG degrees ; enthalpy change, DeltaS degrees ; and entropy change, DeltaH degrees ) for the sorption have been evaluated. The rise in temperature caused a slight decrease in the value of the equilibrium constant (Kc) for the sorption of Cr(VI) ion. The sorption of Cr(VI) on the resin was rapid during the first 15 min and equilibrium was found to be attained within 30 min. The sorption of Cr(VI) onto the resins followed reversible first-order rate kinetics. Such ion exchange resins can be used for the efficient removal of chromium from water and wastewater.","Removal of Cr(VI) from aqueous solution by two Lewatit-anion exchange resins Abs: The sorption of hexavalent chromium, Cr(VI), from aqueous solutions on macroporous resins containing tertiary amine groups (Lewatit MP 62 and Lewatit M 610) was studied at varying Cr(VI) concentrations, adsorbent dose, pH, contact time and temperatures. The concentration of chromium in aqueous solution was determined by inductively coupled plasma spectrometry (ICP-AES). Batch shaking sorption experiments were carried out to evaluate the performance of Lewatit MP 62 and Lewatit M 610 anion exchange resins in the removal of Cr(VI) from aqueous solutions. The ion-exchange process, which is pH dependent, shows maximum removal of Cr(VI) in the pH range 2-6 for an initial Cr(VI) concentration of 100 ppm. The sorption increases with the decrease in pH and slightly decreases with the increase in temperature. Both ion exchangers had high bonding constants with Lewatit M 610 showing stronger binding. It was observed that the maximum adsorption capacity of 0.40 mmol of Cr(VI)/g for Lewatit MP 62 and 0.41 mmol of Cr(VI)/g for Lewatit M 610 was achieved at pH of 5.0. The thermodynamic parameters (free energy change, DeltaG degrees ; enthalpy change, DeltaS degrees ; and entropy change, DeltaH degrees ) for the sorption have been evaluated. The rise in temperature caused a slight decrease in the value of the equilibrium constant (Kc) for the sorption of Cr(VI) ion. The sorption of Cr(VI) on the resin was rapid during the first 15 min and equilibrium was found to be attained within 30 min. The sorption of Cr(VI) onto the resins followed reversible first-order rate kinetics. Such ion exchange resins can be used for the efficient removal of chromium from water and wastewater."
1231913,Bayramo?lu et al. 2005,Modification of surface properties of Lentinus sajor-caju mycelia by physical and chemical methods: evaluation of their Cr6+ removal efficiencies from aqueous medium,"The hexavalent chromium biosorption onto untreated and heat-, acid- and alkali-treated Lentinus sajor-caju mycelia were studied from aqueous solutions. The particles sizes of the fungal mycelia ranged from 100 to 200 microm. The effect of pH, temperature, biosorbent dose, initial concentration of chromium ions, contact time parameters were investigated in a batch system. Biosorption equilibrium was established in about 4 h. The surface charge density of the fungal preparations varied with pH, and the maximum absorption of chromium ions on the fungal preparations were obtained at pH 2.0. The biosorption of chromium ions by the tested fungal preparations increased as the initial concentration of chromium ions increased in the medium. The maximum biosorption capacities of the untreated and heat, HCl- and NaOH-treated fungal biomass were 0.363, 0.613, 0.478 and 0.513 mmol Cr6+ per gram of dry biomass, respectively. The correlation regression coefficients and the Langmuir constant values show that the biosorption process can be well defined by Langmuir equation. The chromium adsorption data were analysed using the first- and the second-order kinetic models. The first-order equation is the most appropriate equation to predict the biosorption capacities of all the fungal preparations. In addition, the polarity and surface energy of the untreated and all the modified biomass film preparations were determined by contact angle measurement. All the tested fungal biomass preparations could be regenerated using 0.1 M NaOH solution.","Modification of surface properties of Lentinus sajor-caju mycelia by physical and chemical methods: evaluation of their Cr6+ removal efficiencies from aqueous medium Abs: The hexavalent chromium biosorption onto untreated and heat-, acid- and alkali-treated Lentinus sajor-caju mycelia were studied from aqueous solutions. The particles sizes of the fungal mycelia ranged from 100 to 200 microm. The effect of pH, temperature, biosorbent dose, initial concentration of chromium ions, contact time parameters were investigated in a batch system. Biosorption equilibrium was established in about 4 h. The surface charge density of the fungal preparations varied with pH, and the maximum absorption of chromium ions on the fungal preparations were obtained at pH 2.0. The biosorption of chromium ions by the tested fungal preparations increased as the initial concentration of chromium ions increased in the medium. The maximum biosorption capacities of the untreated and heat, HCl- and NaOH-treated fungal biomass were 0.363, 0.613, 0.478 and 0.513 mmol Cr6+ per gram of dry biomass, respectively. The correlation regression coefficients and the Langmuir constant values show that the biosorption process can be well defined by Langmuir equation. The chromium adsorption data were analysed using the first- and the second-order kinetic models. The first-order equation is the most appropriate equation to predict the biosorption capacities of all the fungal preparations. In addition, the polarity and surface energy of the untreated and all the modified biomass film preparations were determined by contact angle measurement. All the tested fungal biomass preparations could be regenerated using 0.1 M NaOH solution."
1231912,Hjollund et al. 2005,Spontaneous abortion in IVF couples--a role of male welding exposure,"<strong>BACKGROUND: </strong>Fume from welding of stainless steel contains hexavalent chromium, which in animal studies can induce paternally mediated spontaneous abortion. Human studies have shown conflicting results. The best studies include early pregnancy experience, but these are expensive to conduct. In vitro fertilization (IVF) provides new design opportunities. Our aim was to study pregnancy survival in IVF treated women with respect to paternal welding exposure.<br /><br /><strong>METHODS: </strong>We mailed a questionnaire to 5879 couples from the Danish IVF register that covers all IVF treatments after 1993 (response ratio 68.2%). A subgroup of male metal workers received a second questionnaire on exposure to welding (n = 319 men, response ratio 77%). Information on outcome was collected from national health registers. Survival of the first hCG-positive pregnancy was analysed using Cox regression.<br /><br /><strong>RESULTS: </strong>The proportion of pregnancies terminated by spontaneous abortion before 28 gestational weeks was 18% (n = 91 pregnancies) and 25% (n = 128) in pregnancies with paternal exposure to stainless steel welding and mild steel welding, respectively. In the reference group of 2925 pregnancies the abortion ratio was 28%. The risk ratio for pregnancies with paternal exposure to stainless steel was 0.6 (95% CI 0.4-1.0).<br /><br /><strong>CONCLUSIONS: </strong>We found no increased risk of spontaneous abortion in IVF treated women, who became pregnant by a man exposed to welding of any sort. Since the process of fertilization and selection of IVF pregnancies differs from natural pregnancies the negative results need not apply to other pregnancies.","Spontaneous abortion in IVF couples--a role of male welding exposure Abs: <strong>BACKGROUND: </strong>Fume from welding of stainless steel contains hexavalent chromium, which in animal studies can induce paternally mediated spontaneous abortion. Human studies have shown conflicting results. The best studies include early pregnancy experience, but these are expensive to conduct. In vitro fertilization (IVF) provides new design opportunities. Our aim was to study pregnancy survival in IVF treated women with respect to paternal welding exposure.<br /><br /><strong>METHODS: </strong>We mailed a questionnaire to 5879 couples from the Danish IVF register that covers all IVF treatments after 1993 (response ratio 68.2%). A subgroup of male metal workers received a second questionnaire on exposure to welding (n = 319 men, response ratio 77%). Information on outcome was collected from national health registers. Survival of the first hCG-positive pregnancy was analysed using Cox regression.<br /><br /><strong>RESULTS: </strong>The proportion of pregnancies terminated by spontaneous abortion before 28 gestational weeks was 18% (n = 91 pregnancies) and 25% (n = 128) in pregnancies with paternal exposure to stainless steel welding and mild steel welding, respectively. In the reference group of 2925 pregnancies the abortion ratio was 28%. The risk ratio for pregnancies with paternal exposure to stainless steel was 0.6 (95% CI 0.4-1.0).<br /><br /><strong>CONCLUSIONS: </strong>We found no increased risk of spontaneous abortion in IVF treated women, who became pregnant by a man exposed to welding of any sort. Since the process of fertilization and selection of IVF pregnancies differs from natural pregnancies the negative results need not apply to other pregnancies."
1231911,Marrero and  Manahan 2005,Retention of chromium (VI) on a macroporous char following ChemChar gasification and successive leaching with water and acids,"A granular macroporous char, triple-reverse-burn (TRB) char, was loaded with 23.40 mg Cr/g TRB char from an aqueous solution, and the retained metal was leached by water, 0.66 M nitric acid, concentrated nitric acid, and concentrated hydrochloric acid before and after treatment by a reductive thermal gasification process (ChemChar process developed by ChemChar Research, Inc., Columbia, Missouri). The chromium leachate was analyzed by flame atomic adsorption. Reverse- and forward-mode gasifications were performed on the metal-laden char. With the exception of a 10% mass loss of carbon, the reverse mode gasification process does not change the physical characteristics of the granular char, but does increase the retention of the chromium from 16.7 to 24.2%, depending on the leachant. The forward mode gasification process produces a vitrified (or glasslike) ash residue. There was an 11.6 to 13.1% increase in the retention of the chromium by the slag and ash when compared to the nongasified chromium-loaded TRB char. Chromium (VI) was effectively removed from solution by TRB char and found to be retained to a higher degree on the char after a reductive thermal treatment.","Retention of chromium (VI) on a macroporous char following ChemChar gasification and successive leaching with water and acids Abs: A granular macroporous char, triple-reverse-burn (TRB) char, was loaded with 23.40 mg Cr/g TRB char from an aqueous solution, and the retained metal was leached by water, 0.66 M nitric acid, concentrated nitric acid, and concentrated hydrochloric acid before and after treatment by a reductive thermal gasification process (ChemChar process developed by ChemChar Research, Inc., Columbia, Missouri). The chromium leachate was analyzed by flame atomic adsorption. Reverse- and forward-mode gasifications were performed on the metal-laden char. With the exception of a 10% mass loss of carbon, the reverse mode gasification process does not change the physical characteristics of the granular char, but does increase the retention of the chromium from 16.7 to 24.2%, depending on the leachant. The forward mode gasification process produces a vitrified (or glasslike) ash residue. There was an 11.6 to 13.1% increase in the retention of the chromium by the slag and ash when compared to the nongasified chromium-loaded TRB char. Chromium (VI) was effectively removed from solution by TRB char and found to be retained to a higher degree on the char after a reductive thermal treatment."
1231910,Humphries et al. 2005,Reduction of Cr(VI) by immobilized cells of Desulfovibrio vulgaris NCIMB 8303 and Microbacterium sp. NCIMB 13776,"Hexavalent chromium, a carcinogen and mutagen, can be reduced to Cr(III) by Desulfovibrio vulgaris NCIMB 8303 and Microbacterium sp. NCIMB 13776. This study examined Cr(VI) reduction by immobilized cells of the two strains in a common solution matrix using various entrapment matrices. Chitosan and PVA-borate beads did not retain integrity and supported low or no reduction of Cr(VI) by the cells. A commercial preparation (Lentikats) was stable but also did not support Cr(VI) reduction. K-carrageenan beads were stable in batch suspensions but gel integrity was lost after only 5 h in a flow-through system in the presence of 100 microM Cr(VI). The best immobilization matrices were agar and agarose, where the initial rates of reduction of Cr(VI) (from 500 microM solution) for D. vulgaris NCIMB 8303 and Microbacterium sp. NCIMB 13776 were 127 (agar) and 130 (agarose), and 15 (agar) and 12 (agarose) nmol h(-1) mg dry cell wt(-1), respectively. The higher removal of Cr(VI) by D. vulgaris was also seen in 14-mL packed-bed flow-through columns, where, at a flow rate of 2.4 mL h(-1), the percentage removal of Cr(VI) was approximately 95% and 60% for D. vulgaris and Microbacterium sp., respectively (agar-immobilized cells). The Cr(VI) reducing activities of D. vulgaris and Microbacterium sp. were lost after 159 and 140 h, respectively. Examination of the beads for structural integrity within the columns in situ using magnetic resonance imaging after 24 and 100 h of continuous operation against Cr(VI) (with negligible Cr retained within the columns) showed that agar beads were more stable with time. The most appropriate system for development of a continuous bioprocess is thus the use of D. vulgaris NCIMB 8303 immobilized in an agar gel matrix.","Reduction of Cr(VI) by immobilized cells of Desulfovibrio vulgaris NCIMB 8303 and Microbacterium sp. NCIMB 13776 Abs: Hexavalent chromium, a carcinogen and mutagen, can be reduced to Cr(III) by Desulfovibrio vulgaris NCIMB 8303 and Microbacterium sp. NCIMB 13776. This study examined Cr(VI) reduction by immobilized cells of the two strains in a common solution matrix using various entrapment matrices. Chitosan and PVA-borate beads did not retain integrity and supported low or no reduction of Cr(VI) by the cells. A commercial preparation (Lentikats) was stable but also did not support Cr(VI) reduction. K-carrageenan beads were stable in batch suspensions but gel integrity was lost after only 5 h in a flow-through system in the presence of 100 microM Cr(VI). The best immobilization matrices were agar and agarose, where the initial rates of reduction of Cr(VI) (from 500 microM solution) for D. vulgaris NCIMB 8303 and Microbacterium sp. NCIMB 13776 were 127 (agar) and 130 (agarose), and 15 (agar) and 12 (agarose) nmol h(-1) mg dry cell wt(-1), respectively. The higher removal of Cr(VI) by D. vulgaris was also seen in 14-mL packed-bed flow-through columns, where, at a flow rate of 2.4 mL h(-1), the percentage removal of Cr(VI) was approximately 95% and 60% for D. vulgaris and Microbacterium sp., respectively (agar-immobilized cells). The Cr(VI) reducing activities of D. vulgaris and Microbacterium sp. were lost after 159 and 140 h, respectively. Examination of the beads for structural integrity within the columns in situ using magnetic resonance imaging after 24 and 100 h of continuous operation against Cr(VI) (with negligible Cr retained within the columns) showed that agar beads were more stable with time. The most appropriate system for development of a continuous bioprocess is thus the use of D. vulgaris NCIMB 8303 immobilized in an agar gel matrix."
1231908,Hantson et al. 2005,Hexavalent chromium ingestion: biological markers of nephrotoxicity and genotoxicity,,Hexavalent chromium ingestion: biological markers of nephrotoxicity and genotoxicity Abs: 
1231907,Luippold et al. 2005,Low-level hexavalent chromium exposure and rate of mortality among US chromate production employees,"<strong>OBJECTIVE: </strong>Although numerous studies have reported an elevated lung cancer risk among chromium chemical production employees, few studies have focused on employees hired after major process changes and enhanced industrial hygiene controls were implemented.<br /><br /><strong>METHODS: </strong>This study examines the mortality experience of two post-change cohorts of chromate production employees constituting the current US chromium chemical industry.<br /><br /><strong>RESULTS: </strong>Mortality among chromium chemical workers generally was lower than expected on the basis of national and state-specific referent populations. Lung cancer mortality was 16% lower than expected, with only three lung cancer deaths (3.59 expected).<br /><br /><strong>CONCLUSION: </strong>The absence of an elevated lung cancer risk may be a favorable reflection of the post-change environment. However, longer follow-up allowing an appropriate latency for the entire cohort will be needed to confirm this conclusion.","Low-level hexavalent chromium exposure and rate of mortality among US chromate production employees Abs: <strong>OBJECTIVE: </strong>Although numerous studies have reported an elevated lung cancer risk among chromium chemical production employees, few studies have focused on employees hired after major process changes and enhanced industrial hygiene controls were implemented.<br /><br /><strong>METHODS: </strong>This study examines the mortality experience of two post-change cohorts of chromate production employees constituting the current US chromium chemical industry.<br /><br /><strong>RESULTS: </strong>Mortality among chromium chemical workers generally was lower than expected on the basis of national and state-specific referent populations. Lung cancer mortality was 16% lower than expected, with only three lung cancer deaths (3.59 expected).<br /><br /><strong>CONCLUSION: </strong>The absence of an elevated lung cancer risk may be a favorable reflection of the post-change environment. However, longer follow-up allowing an appropriate latency for the entire cohort will be needed to confirm this conclusion."
1231906,Chundawat and  Sood 2005,Vitamins deficiency in developing chick during chromium intoxication and protection thereof,"Deficiency of various vitamins in postnatally developing chick during chromium intoxication and their recovery during vitamins (B and E) and glutathione therapies has been investigated. Study was concentrated on liver, kidney, muscles and serum. Newly hatched chicks were reared in laboratory. They were treated with a daily dose of 10mg/kg/day potassium dichromate from 2nd to 8th day of their age. Thereafter, one group was sacrificed on 9th day. Second group was kept without intoxication for another 7 days and sacrificed on 16th day. Three groups of chromium pretoxicated animals were exposed to therapeutic agents like vitamins (B and E) and glutathione for another 7 days. These animals were sacrificed on 16th day of their age along with control. Study showed chromium intoxication decreases vitamins (B(1), B(2), B(6) and E) in all the tissues and serum. The maximum decrease was recorded in serum. The 7 days pretoxicated animals kept without any treatment for 7 days revealed a slow increase of vitamins with few exceptions. Nevertheless, the recovery of vitamins was quick and significant during vitamins and glutathione therapy and in some cases control level was achieved.","Vitamins deficiency in developing chick during chromium intoxication and protection thereof Abs: Deficiency of various vitamins in postnatally developing chick during chromium intoxication and their recovery during vitamins (B and E) and glutathione therapies has been investigated. Study was concentrated on liver, kidney, muscles and serum. Newly hatched chicks were reared in laboratory. They were treated with a daily dose of 10mg/kg/day potassium dichromate from 2nd to 8th day of their age. Thereafter, one group was sacrificed on 9th day. Second group was kept without intoxication for another 7 days and sacrificed on 16th day. Three groups of chromium pretoxicated animals were exposed to therapeutic agents like vitamins (B and E) and glutathione for another 7 days. These animals were sacrificed on 16th day of their age along with control. Study showed chromium intoxication decreases vitamins (B(1), B(2), B(6) and E) in all the tissues and serum. The maximum decrease was recorded in serum. The 7 days pretoxicated animals kept without any treatment for 7 days revealed a slow increase of vitamins with few exceptions. Nevertheless, the recovery of vitamins was quick and significant during vitamins and glutathione therapy and in some cases control level was achieved."
1231905,Lan et al. 2005,Catalysis of elemental sulfur nanoparticles on chromium(VI) reduction by sulfide under anaerobic conditions,"Chromate (CrVI) reduction by sulfide was conducted in anaerobic batch experimental systems. The molar ratio of the reduced CrVI to the oxidized S(-II) was 1:1.5 during the reaction, suggesting that the product of sulfide oxidation was elemental sulfur. Under the anaerobic condition, the reaction was pseudo first order initially with respect to CrVI, but the rate was dramatically accelerated at the later stage of the reaction. The rate acceleration was due to catalysis by elemental sulfur nanoparticles; dissolved species such as monomeric elemental sulfur and polysulfides appeared to be ineffective catalysts. Elemental sulfur nanoparticles were capable of adsorbing sulfide and such adsorbed sulfide exhibited much higher reactivity toward CrVI reduction than the aqueous-phase sulfide, resulting in the observed rate acceleration. Kinetic data under various reactant concentrations can be represented by the following empirical kinetic equation: -d[CrVI]/dt = k1 [CrVI][H2S]0.63 + k3[CrVI][triple bond S--SH]0.57. The first term on the right-hand side corresponds to the noncatalytic pathway, with k1 = 1.0 x 10(-3) (microM)(-0.63) min(-1) at pH 7.60 and 8.2 x 10(-5) (microM)-0.63 min(-1) at pH 8.10. The second term, k3[CrVI][triple bond S--SH]b, is the catalytic term with [triple bond S--SH] representing the adsorbed concentration of sulfide on the elemental sulfur nanoparticles (microM). The catalytic term is more important at the later stage of the reaction, as indicated by the observed kinetics and the enhancement of the reaction rate by externally added elemental sulfur nanoparticles. At pH 8.10, k3 = 0.0057 (microM)(-0.57) min(-1).","Catalysis of elemental sulfur nanoparticles on chromium(VI) reduction by sulfide under anaerobic conditions Abs: Chromate (CrVI) reduction by sulfide was conducted in anaerobic batch experimental systems. The molar ratio of the reduced CrVI to the oxidized S(-II) was 1:1.5 during the reaction, suggesting that the product of sulfide oxidation was elemental sulfur. Under the anaerobic condition, the reaction was pseudo first order initially with respect to CrVI, but the rate was dramatically accelerated at the later stage of the reaction. The rate acceleration was due to catalysis by elemental sulfur nanoparticles; dissolved species such as monomeric elemental sulfur and polysulfides appeared to be ineffective catalysts. Elemental sulfur nanoparticles were capable of adsorbing sulfide and such adsorbed sulfide exhibited much higher reactivity toward CrVI reduction than the aqueous-phase sulfide, resulting in the observed rate acceleration. Kinetic data under various reactant concentrations can be represented by the following empirical kinetic equation: -d[CrVI]/dt = k1 [CrVI][H2S]0.63 + k3[CrVI][triple bond S--SH]0.57. The first term on the right-hand side corresponds to the noncatalytic pathway, with k1 = 1.0 x 10(-3) (microM)(-0.63) min(-1) at pH 7.60 and 8.2 x 10(-5) (microM)-0.63 min(-1) at pH 8.10. The second term, k3[CrVI][triple bond S--SH]b, is the catalytic term with [triple bond S--SH] representing the adsorbed concentration of sulfide on the elemental sulfur nanoparticles (microM). The catalytic term is more important at the later stage of the reaction, as indicated by the observed kinetics and the enhancement of the reaction rate by externally added elemental sulfur nanoparticles. At pH 8.10, k3 = 0.0057 (microM)(-0.57) min(-1)."
1231904,Kyung et al. 2005,Simultaneous and synergistic conversion of dyes and heavy metal ions in aqueous TiO2 suspensions under visible-light illumination,"This study reports synergistic effects in the simultaneous conversion of dyes and heavy metal ions in aqueous TiO2/dye/metal ion systems (ternary components) under visible light (lambda &gt; 420 nm). TiO2/Cr(VI)/Acid Orange 7 (AO7), TiO2/Cr(VI)/Rhodamine B (RhB), TiO2/Ag+/AO7, and TiO2/Ag+/RhB were chosen as test systems. Although dyes can be degraded in TiO2 suspensions under visible light, their removal rates were markedly enhanced in the presence of metal ions. Similarly, the reduction rates of metal ions in visible-light-illuminated TiO2 suspensions were negligible, but they were highly accelerated with dyes present. In particular, the synergistic effect in the ternary system of TiO2/Cr(VI)/AO7 was outstanding. The presence of dissolved oxygen increased the photoreduction rate of Cr(VI) despite the fact that Cr(VI) and O2 are competing electron acceptors. This is ascribed to in-situ photogenerated H2O2 from O2, which acts as a reductant of Cr(VI). RhB and Ag+ ions could be also converted simultaneously under visible light both in the presence and absence of TiO2. The visible-light-induced reduction of Ag+ did not occur at all in TiO2/Ag+ system, but it was enabled in both TiO2/Ag+/ RhB and TiO2/Ag+/AO7 to generate Ag particles. On the other hand, the binary systems of Cr(VI)/AO7, Ag+/AO7, and Ag+/RhB show significant visible-light activities for the conversion of both dye and metal ion. In this case, metal ions and dyes seem to form complexes that induce intracomplex electron transfers upon visible-light absorption. The Cr(VI)/RhB system, however, exhibited insignificant visible-light reactivity.","Simultaneous and synergistic conversion of dyes and heavy metal ions in aqueous TiO2 suspensions under visible-light illumination Abs: This study reports synergistic effects in the simultaneous conversion of dyes and heavy metal ions in aqueous TiO2/dye/metal ion systems (ternary components) under visible light (lambda &gt; 420 nm). TiO2/Cr(VI)/Acid Orange 7 (AO7), TiO2/Cr(VI)/Rhodamine B (RhB), TiO2/Ag+/AO7, and TiO2/Ag+/RhB were chosen as test systems. Although dyes can be degraded in TiO2 suspensions under visible light, their removal rates were markedly enhanced in the presence of metal ions. Similarly, the reduction rates of metal ions in visible-light-illuminated TiO2 suspensions were negligible, but they were highly accelerated with dyes present. In particular, the synergistic effect in the ternary system of TiO2/Cr(VI)/AO7 was outstanding. The presence of dissolved oxygen increased the photoreduction rate of Cr(VI) despite the fact that Cr(VI) and O2 are competing electron acceptors. This is ascribed to in-situ photogenerated H2O2 from O2, which acts as a reductant of Cr(VI). RhB and Ag+ ions could be also converted simultaneously under visible light both in the presence and absence of TiO2. The visible-light-induced reduction of Ag+ did not occur at all in TiO2/Ag+ system, but it was enabled in both TiO2/Ag+/ RhB and TiO2/Ag+/AO7 to generate Ag particles. On the other hand, the binary systems of Cr(VI)/AO7, Ag+/AO7, and Ag+/RhB show significant visible-light activities for the conversion of both dye and metal ion. In this case, metal ions and dyes seem to form complexes that induce intracomplex electron transfers upon visible-light absorption. The Cr(VI)/RhB system, however, exhibited insignificant visible-light reactivity."
1231903,Willey et al. 2005,Oxidation of Fe(II) in rainwater,"Photochemically produced Fe(II) is oxidized within hours under environmentally realistic conditions in rainwater. The diurnal variation between photochemical production and reoxidation of Fe(II) observed in our laboratory accurately mimics the behavior of ferrous iron observed in field studies where the highest concentrations of dissolved Fe(ll) occur in afternoon rain during the period of maximum sunlight intensity followed by gradually decreasing concentrations eventually returning to early morning pre-light values. The experimental work presented here, along with the results of kinetics studies done by others, suggests thatthe primary process responsible for the decline in photochemically produced Fe(II) concentrations is oxidation by hydrogen peroxide. This reaction is first order with respect to both the concentrations of Fe(II) and H2O2. The second-order rate constant determined for six different authentic rain samples varied over an order of magnitude and was always less than or equal to the rate constant determined for this reaction in simple acidic solutions. Oxidation of photochemically produced ferrous iron by other oxidants including molecular oxygen, ozone, hydroxyl radical, hydroperoxyl/superoxide radical, and hexavalent chromium were found to be insignificant under the conditions present in rainwater. This study shows that Fe(II) occurs as at least two different chemical species in rain; photochemically produced Fe(II) that is oxidized over time periods of hours, and a background Fe(II) that is protected against oxidation, perhaps by organic complexation, and is stable against oxidation for days. Because the rate of oxidation of photochemically produced Fe(II) does not increase with increasing rainwater pH, the speciation of this more labile form of Fe(II) is also not controlled by simple hydrolysis reactions.","Oxidation of Fe(II) in rainwater Abs: Photochemically produced Fe(II) is oxidized within hours under environmentally realistic conditions in rainwater. The diurnal variation between photochemical production and reoxidation of Fe(II) observed in our laboratory accurately mimics the behavior of ferrous iron observed in field studies where the highest concentrations of dissolved Fe(ll) occur in afternoon rain during the period of maximum sunlight intensity followed by gradually decreasing concentrations eventually returning to early morning pre-light values. The experimental work presented here, along with the results of kinetics studies done by others, suggests thatthe primary process responsible for the decline in photochemically produced Fe(II) concentrations is oxidation by hydrogen peroxide. This reaction is first order with respect to both the concentrations of Fe(II) and H2O2. The second-order rate constant determined for six different authentic rain samples varied over an order of magnitude and was always less than or equal to the rate constant determined for this reaction in simple acidic solutions. Oxidation of photochemically produced ferrous iron by other oxidants including molecular oxygen, ozone, hydroxyl radical, hydroperoxyl/superoxide radical, and hexavalent chromium were found to be insignificant under the conditions present in rainwater. This study shows that Fe(II) occurs as at least two different chemical species in rain; photochemically produced Fe(II) that is oxidized over time periods of hours, and a background Fe(II) that is protected against oxidation, perhaps by organic complexation, and is stable against oxidation for days. Because the rate of oxidation of photochemically produced Fe(II) does not increase with increasing rainwater pH, the speciation of this more labile form of Fe(II) is also not controlled by simple hydrolysis reactions."
1231902,Fathima et al. 2005,Solid waste removes toxic liquid waste: adsorption of chromium(VI) by iron complexed protein waste,"The leather processing industry generates huge amounts of wastes, both in solid and liquid form. Fleshing from animal hides/skins is one such waste that is high in protein content. In this study, raw fleshing has been complexed with iron and is used for removal of chromium(VI). The effect of pH and the initial concentration of chromium(VI) on the removal of Cr(IV) by iron treated fleshing is presented. Iron treatment is shown to greatly improve adsorption of the fleshing for hexavalent chromium. The ultimate adsorption capacity of iron treated fleshing is 51 mg of chromium(VI) per gram of fleshing. That of untreated fleshing is 9 mg/g such that iron treatment increases the adsorption capacity of fleshing by 10-fold. The measured adsorption kinetics is well described by a pseudo-second-order kinetic model. The uptake of chromium(VI) by fleshing is best described by the Langmuir adsorption isotherm model. X-ray photoelectron spectroscopic (XPS) studies show that the iron is incorporated into the protein matrix. Shifts in XPS spectra suggest that dichromate binding occurs with iron at active adsorption sites and that iron treated fleshing removes chromium(VI) without reducing it to chromium(III).","Solid waste removes toxic liquid waste: adsorption of chromium(VI) by iron complexed protein waste Abs: The leather processing industry generates huge amounts of wastes, both in solid and liquid form. Fleshing from animal hides/skins is one such waste that is high in protein content. In this study, raw fleshing has been complexed with iron and is used for removal of chromium(VI). The effect of pH and the initial concentration of chromium(VI) on the removal of Cr(IV) by iron treated fleshing is presented. Iron treatment is shown to greatly improve adsorption of the fleshing for hexavalent chromium. The ultimate adsorption capacity of iron treated fleshing is 51 mg of chromium(VI) per gram of fleshing. That of untreated fleshing is 9 mg/g such that iron treatment increases the adsorption capacity of fleshing by 10-fold. The measured adsorption kinetics is well described by a pseudo-second-order kinetic model. The uptake of chromium(VI) by fleshing is best described by the Langmuir adsorption isotherm model. X-ray photoelectron spectroscopic (XPS) studies show that the iron is incorporated into the protein matrix. Shifts in XPS spectra suggest that dichromate binding occurs with iron at active adsorption sites and that iron treated fleshing removes chromium(VI) without reducing it to chromium(III)."
1231901,Krishna and  Philip 2005,Bioremediation of Cr(VI) in contaminated soils,"Ex situ treatment of hexavalent chromium (Cr(VI)) contaminated soil using a bioreactor-biosorption system was evaluated as a novel remediation alternative. Leaching of Cr(VI) from the contaminated soil using various eluents showed that desorption was strongly affected by the solution pH. The leaching process was accelerated at alkaline conditions (pH 9). Though, desorption potential of ethylene diamine tetra acetic acid (EDTA) was the maximum among various eluents tried, molasses (5 g/L) could also elute 72% of Cr(VI). Cr(VI) reduction studies were carried out under aerobic and facultative anaerobic conditions using the bacterial isolates from contaminated soil. Cr(VI) reduction was moderately higher in aerobic conditions than in facultative anaerobic conditions. The effect of various electron donors on Cr(VI) reduction was also investigated. Among five electron donors screened, peptone (10 g/L) showed maximum Cr(VI) reduction followed by molasses (10 g/L). The time required for complete Cr(VI) reduction was increased with increase in the initial Cr(VI) concentration. However, specific Cr(VI) reduction was increased with increase in initial Cr(VI) concentration. Sulfates and nitrates did not compete with Cr(VI) for accepting the electrons. A bioreactor was developed for the detoxification of Cr(VI). Above 80% of Cr(VI) reduction was achieved in the bioreactor with an initial Cr(VI) concentration of 50 mg/L at an HRT of 8 h. An adsorption column was developed using Ganoderm lucidum (a wood rooting fungus) as the adsorbent for the removal of trivalent chromium (Cr(III)) and excess electron donor from the effluent of the bioreactor. The specific Cr(III) adsorption capacity of G. lucidum in the column was 576 mg/g. The new biosystem seems to be a promising alternative for the ex situ bioremediation of Cr(VI) contaminated soils.","Bioremediation of Cr(VI) in contaminated soils Abs: Ex situ treatment of hexavalent chromium (Cr(VI)) contaminated soil using a bioreactor-biosorption system was evaluated as a novel remediation alternative. Leaching of Cr(VI) from the contaminated soil using various eluents showed that desorption was strongly affected by the solution pH. The leaching process was accelerated at alkaline conditions (pH 9). Though, desorption potential of ethylene diamine tetra acetic acid (EDTA) was the maximum among various eluents tried, molasses (5 g/L) could also elute 72% of Cr(VI). Cr(VI) reduction studies were carried out under aerobic and facultative anaerobic conditions using the bacterial isolates from contaminated soil. Cr(VI) reduction was moderately higher in aerobic conditions than in facultative anaerobic conditions. The effect of various electron donors on Cr(VI) reduction was also investigated. Among five electron donors screened, peptone (10 g/L) showed maximum Cr(VI) reduction followed by molasses (10 g/L). The time required for complete Cr(VI) reduction was increased with increase in the initial Cr(VI) concentration. However, specific Cr(VI) reduction was increased with increase in initial Cr(VI) concentration. Sulfates and nitrates did not compete with Cr(VI) for accepting the electrons. A bioreactor was developed for the detoxification of Cr(VI). Above 80% of Cr(VI) reduction was achieved in the bioreactor with an initial Cr(VI) concentration of 50 mg/L at an HRT of 8 h. An adsorption column was developed using Ganoderm lucidum (a wood rooting fungus) as the adsorbent for the removal of trivalent chromium (Cr(III)) and excess electron donor from the effluent of the bioreactor. The specific Cr(III) adsorption capacity of G. lucidum in the column was 576 mg/g. The new biosystem seems to be a promising alternative for the ex situ bioremediation of Cr(VI) contaminated soils."
1231899,Porter et al. 2005,Reductive activation of Cr(Vi) by nitric oxide synthase,"Chromium(VI) is a recognized toxicant whose effects have been linked to its reduction to lower oxidation states. Although Cr(VI) is reduced by several systems, it is anticipated that its reduction by nitric oxide synthase (NOS) could have significant effects in endothelial and brain cells that express high constitutive levels of the enzyme. This possibility was examined by electron paramagnetic resonance that showed the formation of a stable Cr(V) species from NOS/Cr(VI). The formation of Cr(V) was calcium/calmodulin-independent indicating that Cr(VI) to Cr(V) reduction occurs at the flavin-containing domain of NOS. Accordingly, Cr(VI) reduction by the reductase domain of NOS and the chimera protein cytochrome-P450-reductase+tail-nNOS also generated Cr(V). Activation of tetrahydrobiopterin (BH(4))-free NOS with calcium/calmodulin diminished Cr(V) steady-state levels while increasing superoxide formation. Since SOD restored Cr(V) to control levels, this result was taken as evidence for a reaction between Cr(V) and superoxide. Supplementation of NOS with BH(4) cofactor not only failed to increase Cr(V) yields but generated superoxide and hydroxyl radical. Since the holoenzyme does not generate superoxide, this reaction indicated that Cr(V) mediates the oxidation of BH(4)-bound to the enzyme. In the presence of L-arginine, however, Cr(VI) neither enhances superoxide release nor inhibits NO formation from fully active NOS. This suggests that L-arginine protects BH(4) from Cr(V)-mediated oxidation. While Cr(V) was inactive toward NO, spin trapping experiments with 5-tert-butoxycarbonyl 5-methyl-1-pyrroline N-oxide and oxygen consumption measurements showed that Cr(V) reacts with superoxide by a one-electron-transfer mechanism to generate oxygen and Cr(IV). Thus, reduction of Cr(VI) to Cr(V) by NOS occurs in resting and fully active states. It is likely that the reaction between Cr(V) and superoxide influences the cytotoxic mechanisms of Cr(VI) in cells.","Reductive activation of Cr(Vi) by nitric oxide synthase Abs: Chromium(VI) is a recognized toxicant whose effects have been linked to its reduction to lower oxidation states. Although Cr(VI) is reduced by several systems, it is anticipated that its reduction by nitric oxide synthase (NOS) could have significant effects in endothelial and brain cells that express high constitutive levels of the enzyme. This possibility was examined by electron paramagnetic resonance that showed the formation of a stable Cr(V) species from NOS/Cr(VI). The formation of Cr(V) was calcium/calmodulin-independent indicating that Cr(VI) to Cr(V) reduction occurs at the flavin-containing domain of NOS. Accordingly, Cr(VI) reduction by the reductase domain of NOS and the chimera protein cytochrome-P450-reductase+tail-nNOS also generated Cr(V). Activation of tetrahydrobiopterin (BH(4))-free NOS with calcium/calmodulin diminished Cr(V) steady-state levels while increasing superoxide formation. Since SOD restored Cr(V) to control levels, this result was taken as evidence for a reaction between Cr(V) and superoxide. Supplementation of NOS with BH(4) cofactor not only failed to increase Cr(V) yields but generated superoxide and hydroxyl radical. Since the holoenzyme does not generate superoxide, this reaction indicated that Cr(V) mediates the oxidation of BH(4)-bound to the enzyme. In the presence of L-arginine, however, Cr(VI) neither enhances superoxide release nor inhibits NO formation from fully active NOS. This suggests that L-arginine protects BH(4) from Cr(V)-mediated oxidation. While Cr(V) was inactive toward NO, spin trapping experiments with 5-tert-butoxycarbonyl 5-methyl-1-pyrroline N-oxide and oxygen consumption measurements showed that Cr(V) reacts with superoxide by a one-electron-transfer mechanism to generate oxygen and Cr(IV). Thus, reduction of Cr(VI) to Cr(V) by NOS occurs in resting and fully active states. It is likely that the reaction between Cr(V) and superoxide influences the cytotoxic mechanisms of Cr(VI) in cells."
1231898,Wei et al. 2005,XANES study of Cr sorbed by a kitchen waste compost from water,"A kitchen waste compost was used to sorb Cr for various times from water containing either Cr(NO3)3 or CrO3 in different concentrations. Scanning electron microscopy (SEM) results show that the composts have been partially oxidized by Cr(VI) during the sorption experiments. X-ray absorption near edge structure (XANES) simulation suggests that about 54.1-61.0% Cr sorbed on the compost is in form of organic Cr(III) through ionic exchange process with the rest being existent as Cr(NO3)3 in the Cr(III) sorption case; no Cr(OH)3 is observed or expected because the solution pH after sorption experiments is &lt;or= 3.31. However in the Cr(VI) sorption cases, about 18.0-24.9% of the total sorbed Cr is in form of Cr(OH)3 precipitate due to the Cr(VI) chemical reduction by the compost and a contaminant increase in solution pH to &gt;or= 5.94. Moreover, organic Cr(III) represents about 51.7-69.0% of the total sorbed Cr, and the rest (6.1-28.5%) is Cr(VI).","XANES study of Cr sorbed by a kitchen waste compost from water Abs: A kitchen waste compost was used to sorb Cr for various times from water containing either Cr(NO3)3 or CrO3 in different concentrations. Scanning electron microscopy (SEM) results show that the composts have been partially oxidized by Cr(VI) during the sorption experiments. X-ray absorption near edge structure (XANES) simulation suggests that about 54.1-61.0% Cr sorbed on the compost is in form of organic Cr(III) through ionic exchange process with the rest being existent as Cr(NO3)3 in the Cr(III) sorption case; no Cr(OH)3 is observed or expected because the solution pH after sorption experiments is &lt;or= 3.31. However in the Cr(VI) sorption cases, about 18.0-24.9% of the total sorbed Cr is in form of Cr(OH)3 precipitate due to the Cr(VI) chemical reduction by the compost and a contaminant increase in solution pH to &gt;or= 5.94. Moreover, organic Cr(III) represents about 51.7-69.0% of the total sorbed Cr, and the rest (6.1-28.5%) is Cr(VI)."
1231897,Zhou and  Yang 2004,Intensification of adsorption process by using the pyrolytic char from waste tires to remove chromium (VI) from wastewater,"Pyrolysis has the potential of transforming waste into valuable recyclable products. Pyrolytic char (PC) is one of the most important products from the pyrolysis of used tires. One of the most significant applications for pyrolytic char recovered is used for the removal of Cr(VI) in the wastewater effluent to control waste by waste. The surface chemistry properties of surface element distribution/concentration and chemical structure were examined for the pyrolytic char and the commercial activated carbon (CAC) respectively. The results showed that surfaces of PC possesses a large amount of ester and hydrocarbon graft, whereas there are mainly carbon functional components of C-OH, C=O and COOH on the surface of CAC. Therefore the surface electronegativity of PC is lower than that of CAC in the water. The repulsive interactions between the surfaces of PC and the negatively charged Cr(VI) ion are weaker than that of CAC, which results in an intensification of the adsorption process by the utilization of PC. The adsorption isotherms of Cr(VI) ion on the two kinds of carbons were determined experimentally. The larger adsorption amount on the PC in the case of Cr(VI) may be attributed mainly to its special surface micro-chemical environment. The mechanism of the removal Cr(VI) from aqueous solution was assumed to be the integration of adsorption and redox reaction. The adsorption was the rate-controlled step for Cr(VI) removal. The adsorption of Cr(VI) was identified as pseudo-second-order kinetics. The rate constants of adsorption were evaluated.","Intensification of adsorption process by using the pyrolytic char from waste tires to remove chromium (VI) from wastewater Abs: Pyrolysis has the potential of transforming waste into valuable recyclable products. Pyrolytic char (PC) is one of the most important products from the pyrolysis of used tires. One of the most significant applications for pyrolytic char recovered is used for the removal of Cr(VI) in the wastewater effluent to control waste by waste. The surface chemistry properties of surface element distribution/concentration and chemical structure were examined for the pyrolytic char and the commercial activated carbon (CAC) respectively. The results showed that surfaces of PC possesses a large amount of ester and hydrocarbon graft, whereas there are mainly carbon functional components of C-OH, C=O and COOH on the surface of CAC. Therefore the surface electronegativity of PC is lower than that of CAC in the water. The repulsive interactions between the surfaces of PC and the negatively charged Cr(VI) ion are weaker than that of CAC, which results in an intensification of the adsorption process by the utilization of PC. The adsorption isotherms of Cr(VI) ion on the two kinds of carbons were determined experimentally. The larger adsorption amount on the PC in the case of Cr(VI) may be attributed mainly to its special surface micro-chemical environment. The mechanism of the removal Cr(VI) from aqueous solution was assumed to be the integration of adsorption and redox reaction. The adsorption was the rate-controlled step for Cr(VI) removal. The adsorption of Cr(VI) was identified as pseudo-second-order kinetics. The rate constants of adsorption were evaluated."
1231896,Ozdemir et al. 2005,Effect of MnSO4 on the chromium removal from the leather industry wastewater,"Chromium (VI) is one of the heavy metals in water and wastewater that has the most toxic characteristic. Consequently, it is dangerous for human and environmental health. Various methods are used for removal of the chromium from wastewater, and new methods have been developed in recent years. Recent studies and investigations on the removal of environmental pollution selected methods that were economical, of optimum efficiently and could be carried out easily. In this study, the removal of Cr6+ in the leather industry wastewater is investigated using MnSO4 that was used easily and economically. Experimental studies are performed in two phases. In the first phase, the optimum MnSO4 dose for removal of Cr6+ was determined. In the second phase, the optimum pH was studied. About 96% removal of chromium was launched with 530 mg l(-1) MnSO4 dose at pH value 9 in the wastewater sample.","Effect of MnSO4 on the chromium removal from the leather industry wastewater Abs: Chromium (VI) is one of the heavy metals in water and wastewater that has the most toxic characteristic. Consequently, it is dangerous for human and environmental health. Various methods are used for removal of the chromium from wastewater, and new methods have been developed in recent years. Recent studies and investigations on the removal of environmental pollution selected methods that were economical, of optimum efficiently and could be carried out easily. In this study, the removal of Cr6+ in the leather industry wastewater is investigated using MnSO4 that was used easily and economically. Experimental studies are performed in two phases. In the first phase, the optimum MnSO4 dose for removal of Cr6+ was determined. In the second phase, the optimum pH was studied. About 96% removal of chromium was launched with 530 mg l(-1) MnSO4 dose at pH value 9 in the wastewater sample."
1231895,Rudolf et al. 2005,Hexavalent chromium disrupts the actin cytoskeleton and induces mitochondria-dependent apoptosis in human dermal fibroblasts,"Exposure to hexavalent chromium causes various adverse effects including deep skin ulcerations and allergic dermatitis. Because of many potential intracellular targets for hexavalent chromium toxicity, its mechanisms of action are not entirely understood. To investigate the role of the cytoskeleton and mitochondria in this process, primary human dermal fibroblasts were exposed to various concentrations of potassium chromate for 24 h. The followed markers included cell motility, cytoskeletal organization, oxidative stress, mitochondrial activity and activation of the apoptotic cascade. Potassium chromate (1.5-45 microM) induced time- and concentration-dependent cell shrinkage, reorganization of cytoskeleton and loss of motile activity in fibroblasts. In some cells this was followed by membrane blebbing. Dynamic changes in cell morphology were accompanied with the loss of mitochondrial membrane potential, increased oxidative stress and release of cytochrome c. Apoptosis was confirmed by detection of activated caspase-3 and nuclear fragmentation. The results indicate that in fibroblasts hexavalent chromium-induced damage to cytoskeleton and mitochondria might occur concurrently at relatively early stages of exposure. Furthermore, alterations of these targets seem to activate mitochondria-dependent and- independent apoptosis.","Hexavalent chromium disrupts the actin cytoskeleton and induces mitochondria-dependent apoptosis in human dermal fibroblasts Abs: Exposure to hexavalent chromium causes various adverse effects including deep skin ulcerations and allergic dermatitis. Because of many potential intracellular targets for hexavalent chromium toxicity, its mechanisms of action are not entirely understood. To investigate the role of the cytoskeleton and mitochondria in this process, primary human dermal fibroblasts were exposed to various concentrations of potassium chromate for 24 h. The followed markers included cell motility, cytoskeletal organization, oxidative stress, mitochondrial activity and activation of the apoptotic cascade. Potassium chromate (1.5-45 microM) induced time- and concentration-dependent cell shrinkage, reorganization of cytoskeleton and loss of motile activity in fibroblasts. In some cells this was followed by membrane blebbing. Dynamic changes in cell morphology were accompanied with the loss of mitochondrial membrane potential, increased oxidative stress and release of cytochrome c. Apoptosis was confirmed by detection of activated caspase-3 and nuclear fragmentation. The results indicate that in fibroblasts hexavalent chromium-induced damage to cytoskeleton and mitochondria might occur concurrently at relatively early stages of exposure. Furthermore, alterations of these targets seem to activate mitochondria-dependent and- independent apoptosis."
1231893,Astrup et al. 2005,Chromium release from waste incineration air-pollution-control residues,"Cr release overtime was investigated in batch experiments for eleven air-pollution-control residues from eight different municipal solid waste incinerators covering all majorflue gas cleaning technologies. Cr released during 168 h of contact with water showed significant variations among the residues studied. Also for the individual residue, large variations were observed depending on the liquid-to-solid ratio used in the leaching test and the degree of carbonation. It is argued that Al(0) present in the residues can control Cr leaching by reducing Cr(VI) released from the solid phase by dissolution and that exposure to oxygen-either prior to or during the leaching test-depletes the reduction capacity of Al(0) leading to increased Cr leaching. A dynamic model is shown to describe Cr release from all investigated residues by accounting for Al(0) oxidation with Cr(VI), O2, and water as well as Cr(VI) dissolution. The paper reveals that Al-O2-Cr(VI) interactions must be considered very carefully when interpreting Cr leaching data.","Chromium release from waste incineration air-pollution-control residues Abs: Cr release overtime was investigated in batch experiments for eleven air-pollution-control residues from eight different municipal solid waste incinerators covering all majorflue gas cleaning technologies. Cr released during 168 h of contact with water showed significant variations among the residues studied. Also for the individual residue, large variations were observed depending on the liquid-to-solid ratio used in the leaching test and the degree of carbonation. It is argued that Al(0) present in the residues can control Cr leaching by reducing Cr(VI) released from the solid phase by dissolution and that exposure to oxygen-either prior to or during the leaching test-depletes the reduction capacity of Al(0) leading to increased Cr leaching. A dynamic model is shown to describe Cr release from all investigated residues by accounting for Al(0) oxidation with Cr(VI), O2, and water as well as Cr(VI) dissolution. The paper reveals that Al-O2-Cr(VI) interactions must be considered very carefully when interpreting Cr leaching data."
1231892,Karthikeyan et al. 2005,Chromium(VI) adsorption from aqueous solution by Hevea Brasilinesis sawdust activated carbon,"Adsorption capacity of Cr(VI) onto Hevea Brasilinesis (Rubber wood) sawdust activated carbon was investigated in a batch system by considering the effects of various parameters like contact time, initial concentration, pH and temperature. Cr(VI) removal is pH dependent and found to be maximum at pH 2.0. Increases in adsorption capacity with increase in temperature indicate that the adsorption reaction is endothermic. Based on this study, the thermodynamic parameters like standard Gibb's free energy (DeltaG degrees ), standard enthalpy (DeltaH degrees ) and standard entropy (DeltaS degrees ) were evaluated. Adsorption kinetics of Cr(VI) ions onto rubber wood sawdust activated carbon were analyzed by pseudo first-order and pseudo second-order models. Pseudo second-order model was found to explain the kinetics of Cr(VI) adsorption most effectively. Intraparticle diffusion studies at different temperatures show that the mechanism of adsorption is mainly dependent on diffusion. The rate of intraparticle diffusion, film diffusion coefficient and pore diffusion coefficient at various temperatures were evaluated. The Langmuir, Freundlich and Temkin isotherm were used to describe the adsorption equilibrium studies of rubber wood sawdust activated carbon at different temperatures. Langmuir isotherm shows better fit than Freundlich and Temkin isotherm in the temperature range studied. The result shows that the rubber wood sawdust activated carbon can be efficiently used for the treatment of wastewaters containing chromium as a low cost alternative compared to commercial activated carbon and other adsorbents reported.","Chromium(VI) adsorption from aqueous solution by Hevea Brasilinesis sawdust activated carbon Abs: Adsorption capacity of Cr(VI) onto Hevea Brasilinesis (Rubber wood) sawdust activated carbon was investigated in a batch system by considering the effects of various parameters like contact time, initial concentration, pH and temperature. Cr(VI) removal is pH dependent and found to be maximum at pH 2.0. Increases in adsorption capacity with increase in temperature indicate that the adsorption reaction is endothermic. Based on this study, the thermodynamic parameters like standard Gibb's free energy (DeltaG degrees ), standard enthalpy (DeltaH degrees ) and standard entropy (DeltaS degrees ) were evaluated. Adsorption kinetics of Cr(VI) ions onto rubber wood sawdust activated carbon were analyzed by pseudo first-order and pseudo second-order models. Pseudo second-order model was found to explain the kinetics of Cr(VI) adsorption most effectively. Intraparticle diffusion studies at different temperatures show that the mechanism of adsorption is mainly dependent on diffusion. The rate of intraparticle diffusion, film diffusion coefficient and pore diffusion coefficient at various temperatures were evaluated. The Langmuir, Freundlich and Temkin isotherm were used to describe the adsorption equilibrium studies of rubber wood sawdust activated carbon at different temperatures. Langmuir isotherm shows better fit than Freundlich and Temkin isotherm in the temperature range studied. The result shows that the rubber wood sawdust activated carbon can be efficiently used for the treatment of wastewaters containing chromium as a low cost alternative compared to commercial activated carbon and other adsorbents reported."
1231891,Sumner et al. 2005,Oxidative protein damage causes chromium toxicity in yeast,"Oxidative damage in microbial cells occurs during exposure to the toxic metal chromium, but it is not certain whether such oxidation accounts for the toxicity of Cr. Here, a Saccharomyces cerevisiae sod1Delta mutant (defective for the Cu,Zn-superoxide dismutase) was found to be hypersensitive to Cr(VI) toxicity under aerobic conditions, but this phenotype was suppressed under anaerobic conditions. Studies with cells expressing a Sod1p variant (Sod1(H46C)) showed that the superoxide dismutase activity rather than the metal-binding function of Sod1p was required for Cr resistance. To help identify the macromolecular target(s) of Cr-dependent oxidative damage, cells deficient for the reduction of phospholipid hydroperoxides (gpx3Delta and gpx1Delta/gpx2Delta/gpx3Delta) and for the repair of DNA oxidation (ogg1Delta and rad30Delta/ogg1Delta) were tested, but were found not to be Cr-sensitive. In contrast, S. cerevisiae msraDelta (mxr1Delta) and msrbDelta (ycl033cDelta) mutants defective for peptide methionine sulfoxide reductase (MSR) activity exhibited a Cr sensitivity phenotype, and cells overexpressing these enzymes were Cr-resistant. Overexpression of MSRs also suppressed the Cr sensitivity of sod1Delta cells. The inference that protein oxidation is a primary mechanism of Cr toxicity was corroborated by an observed approximately 20-fold increase in the cellular levels of protein carbonyls within 30 min of Cr exposure. Carbonylation was not distributed evenly among the expressed proteins of the cells; certain glycolytic enzymes and heat-shock proteins were specifically targeted by Cr-dependent oxidative damage. This study establishes an oxidative mode of Cr toxicity in S. cerevisiae, which primarily involves oxidative damage to cellular proteins.","Oxidative protein damage causes chromium toxicity in yeast Abs: Oxidative damage in microbial cells occurs during exposure to the toxic metal chromium, but it is not certain whether such oxidation accounts for the toxicity of Cr. Here, a Saccharomyces cerevisiae sod1Delta mutant (defective for the Cu,Zn-superoxide dismutase) was found to be hypersensitive to Cr(VI) toxicity under aerobic conditions, but this phenotype was suppressed under anaerobic conditions. Studies with cells expressing a Sod1p variant (Sod1(H46C)) showed that the superoxide dismutase activity rather than the metal-binding function of Sod1p was required for Cr resistance. To help identify the macromolecular target(s) of Cr-dependent oxidative damage, cells deficient for the reduction of phospholipid hydroperoxides (gpx3Delta and gpx1Delta/gpx2Delta/gpx3Delta) and for the repair of DNA oxidation (ogg1Delta and rad30Delta/ogg1Delta) were tested, but were found not to be Cr-sensitive. In contrast, S. cerevisiae msraDelta (mxr1Delta) and msrbDelta (ycl033cDelta) mutants defective for peptide methionine sulfoxide reductase (MSR) activity exhibited a Cr sensitivity phenotype, and cells overexpressing these enzymes were Cr-resistant. Overexpression of MSRs also suppressed the Cr sensitivity of sod1Delta cells. The inference that protein oxidation is a primary mechanism of Cr toxicity was corroborated by an observed approximately 20-fold increase in the cellular levels of protein carbonyls within 30 min of Cr exposure. Carbonylation was not distributed evenly among the expressed proteins of the cells; certain glycolytic enzymes and heat-shock proteins were specifically targeted by Cr-dependent oxidative damage. This study establishes an oxidative mode of Cr toxicity in S. cerevisiae, which primarily involves oxidative damage to cellular proteins."
1231890,Sivakumar and  Subbhuraam 2005,Toxicity of chromium(III) and chromium(VI) to the earthworm Eisenia fetida,"The effects of Cr(III) and Cr(VI) on the survival, behavior, and morphology of the earthworm, Eisenia fetida, in water at pH 6, 7, and 8 and their toxicity in 10 different soils and an organic substrate have been assessed. A decrease in the pH of water resulted in increased toxicity of Cr to the earthworm. In water, both Cr species produced behavioral changes and morphological symptoms. The 48-h LC(50) values of Cr(III) at pH 6, 7, and 8 were 1.93, 2.55, and 2.78 mg/L, and those of Cr(VI) were 0.47, 0.61, and 0.63 mg/L, respectively. The 14-day median lethal concentrations (LC(50)) of Cr(III) and Cr(VI) for earthworm range from 1656 to 1902 mg/kg for Cr(III) and from 222 to 257 mg/kg for Cr(VI) in soil. In the organic substrate, the LC(50) values of Cr(III) and Cr(VI) were 1635 and 219 mg/kg, respectively. Stepwise multiple regression analysis predicted that clay content of soils accounted for 92% and 88% of the variation in the LC(50) values of Cr(III) and Cr(VI), respectively.","Toxicity of chromium(III) and chromium(VI) to the earthworm Eisenia fetida Abs: The effects of Cr(III) and Cr(VI) on the survival, behavior, and morphology of the earthworm, Eisenia fetida, in water at pH 6, 7, and 8 and their toxicity in 10 different soils and an organic substrate have been assessed. A decrease in the pH of water resulted in increased toxicity of Cr to the earthworm. In water, both Cr species produced behavioral changes and morphological symptoms. The 48-h LC(50) values of Cr(III) at pH 6, 7, and 8 were 1.93, 2.55, and 2.78 mg/L, and those of Cr(VI) were 0.47, 0.61, and 0.63 mg/L, respectively. The 14-day median lethal concentrations (LC(50)) of Cr(III) and Cr(VI) for earthworm range from 1656 to 1902 mg/kg for Cr(III) and from 222 to 257 mg/kg for Cr(VI) in soil. In the organic substrate, the LC(50) values of Cr(III) and Cr(VI) were 1635 and 219 mg/kg, respectively. Stepwise multiple regression analysis predicted that clay content of soils accounted for 92% and 88% of the variation in the LC(50) values of Cr(III) and Cr(VI), respectively."
1231888,Alvarez-Ayuso and  Nugteren 2005,Purification of chromium(VI) finishing wastewaters using calcined and uncalcined Mg-Al-CO3-hydrotalcite,"The applicability of calcined and uncalcined hydrotalcite for the purification of industrial effluents has been studied using chromium finishing wastewaters. Using a batch method, the influence of the initial concentration of chromium (10-450mg/l), hydrotalcite (HT) dose (0.5-5g/l) and time (0.5-72h) has been evaluated. The process could be described by the Langmuir model and gave a maximum removal of chromium of 16.3mg Cr(VI)/g on uncalcined HT and 128mg Cr(VI)/g on calcined hydrotalcite (C-HT). Removal using the calcined product provided an effective system to treat chromium finishing wastewaters with the most stringent discharge limit for such industrial streams being achieved with between two and four consecutive removal cycles on C-HT at a dose of 2g/l.","Purification of chromium(VI) finishing wastewaters using calcined and uncalcined Mg-Al-CO3-hydrotalcite Abs: The applicability of calcined and uncalcined hydrotalcite for the purification of industrial effluents has been studied using chromium finishing wastewaters. Using a batch method, the influence of the initial concentration of chromium (10-450mg/l), hydrotalcite (HT) dose (0.5-5g/l) and time (0.5-72h) has been evaluated. The process could be described by the Langmuir model and gave a maximum removal of chromium of 16.3mg Cr(VI)/g on uncalcined HT and 128mg Cr(VI)/g on calcined hydrotalcite (C-HT). Removal using the calcined product provided an effective system to treat chromium finishing wastewaters with the most stringent discharge limit for such industrial streams being achieved with between two and four consecutive removal cycles on C-HT at a dose of 2g/l."
1231886,He and  Traina 2005,Cr(VI) reduction and immobilization by magnetite under alkaline pH conditions: the role of passivation,"This study investigated Cr(VI) reduction and immobilization by magnetite under alkaline pH conditions similar to those present at the Hanford site. Compared to acidic and neutral pH, chromium(VI) reduction by magnetite at high pH conditions is limited (&lt;20% of potential reduction capacity), and the extent of reduction does not vary significantly with increasing NaOH concentration. This is due to the formation of maghemite, goethite, and/or Fe1-xCrxOOH, which may form a passivation layer on the magnetite surface, stopping further chromate reduction. Maghemite is formed in lower NaOH concentrations. The extent of goethite formation increases with NaOH concentration. Goethite may be formed through two mechanisms: (i) dissolution of magnetite leads to the precipitation of goethite and/or (ii) dissolution of newly formed maghemite intermediate, followed by precipitation of goethite. Extended X-ray absorption fine structure spectroscopy shows that Cr has a similar structural environment at alkaline pH as at acidic and circumneutral conditions.","Cr(VI) reduction and immobilization by magnetite under alkaline pH conditions: the role of passivation Abs: This study investigated Cr(VI) reduction and immobilization by magnetite under alkaline pH conditions similar to those present at the Hanford site. Compared to acidic and neutral pH, chromium(VI) reduction by magnetite at high pH conditions is limited (&lt;20% of potential reduction capacity), and the extent of reduction does not vary significantly with increasing NaOH concentration. This is due to the formation of maghemite, goethite, and/or Fe1-xCrxOOH, which may form a passivation layer on the magnetite surface, stopping further chromate reduction. Maghemite is formed in lower NaOH concentrations. The extent of goethite formation increases with NaOH concentration. Goethite may be formed through two mechanisms: (i) dissolution of magnetite leads to the precipitation of goethite and/or (ii) dissolution of newly formed maghemite intermediate, followed by precipitation of goethite. Extended X-ray absorption fine structure spectroscopy shows that Cr has a similar structural environment at alkaline pH as at acidic and circumneutral conditions."
1231885,Lee and  Hering 2005,"Oxidative dissolution of chromium(III) hydroxide at pH 9, 3, and 2 with product inhibition at pH 2","Hexavalent chromium, Cr(VI), can be immobilized under neutral to alkaline conditions by reduction to Cr(III); similarly, the mobility of naturally occurring Cr in soils and sediments can be limited by its occurrence in the +III oxidation state. Conversely, the oxidation of Cr(IIi) to Cr(VI) increases both its toxicity and often its mobility. Dissolution of Cr-(OH)3(s) in 0.01 M NaNO3 suspensions was examined in batch experiments in the presence and absence of the strong oxidant sodium hypochlorite (NaOCI). Dissolution of Cr(OH)3(s) (1.0 g/L) was accelerated in the presence of excess strong oxidant (20 mM) at pH 9 by a factor of ca. 200 and to a lesser extent at pH 2 and 3. Linear kinetics of oxidative dissolution was observed at pH 9 and 3. In contrast, the rate of Cr release at pH 2 decreased rapidly with time, and within 2.5 h, the dissolution reaction was completely inhibited. Under oxidizing conditions, Cr released into solution is expected to be present as Cr(VI), which sorbs strongly to Cr(OH)3(s) at low pH. Cr(VI) sorption followed a Langmuir isotherm and reached maximum sorption densities of 308 +/- 8 and 271 +/- 10 micromol/g at pH 3 and 2, respectively. However, sorption of Cr(VI) (putatively formed during oxidative dissolution) cannot explain the observed inhibition of the reaction because (1) sorption occurs at both pH 2 and 3 but inhibition only at pH 2 and (2) preequilibration of Cr(OH)3(s) with Cr(VI) did not affectthe rate of dissolution observed upon the addition of the oxidant. Thus, we hypothesize that the inhibition of (net) oxidative dissolution at pH 2 may be the result of secondary precipitation of a chromic hydroxy chromate phase.","Oxidative dissolution of chromium(III) hydroxide at pH 9, 3, and 2 with product inhibition at pH 2 Abs: Hexavalent chromium, Cr(VI), can be immobilized under neutral to alkaline conditions by reduction to Cr(III); similarly, the mobility of naturally occurring Cr in soils and sediments can be limited by its occurrence in the +III oxidation state. Conversely, the oxidation of Cr(IIi) to Cr(VI) increases both its toxicity and often its mobility. Dissolution of Cr-(OH)3(s) in 0.01 M NaNO3 suspensions was examined in batch experiments in the presence and absence of the strong oxidant sodium hypochlorite (NaOCI). Dissolution of Cr(OH)3(s) (1.0 g/L) was accelerated in the presence of excess strong oxidant (20 mM) at pH 9 by a factor of ca. 200 and to a lesser extent at pH 2 and 3. Linear kinetics of oxidative dissolution was observed at pH 9 and 3. In contrast, the rate of Cr release at pH 2 decreased rapidly with time, and within 2.5 h, the dissolution reaction was completely inhibited. Under oxidizing conditions, Cr released into solution is expected to be present as Cr(VI), which sorbs strongly to Cr(OH)3(s) at low pH. Cr(VI) sorption followed a Langmuir isotherm and reached maximum sorption densities of 308 +/- 8 and 271 +/- 10 micromol/g at pH 3 and 2, respectively. However, sorption of Cr(VI) (putatively formed during oxidative dissolution) cannot explain the observed inhibition of the reaction because (1) sorption occurs at both pH 2 and 3 but inhibition only at pH 2 and (2) preequilibration of Cr(OH)3(s) with Cr(VI) did not affectthe rate of dissolution observed upon the addition of the oxidant. Thus, we hypothesize that the inhibition of (net) oxidative dissolution at pH 2 may be the result of secondary precipitation of a chromic hydroxy chromate phase."
1231883,Park et al. 2005,Studies on hexavalent chromium biosorption by chemically-treated biomass of Ecklonia sp,"The biomass of the brown seaweed, Ecklonia sp., is capable of reducing Cr(VI) to Cr(III). However, very little is known about the mechanism of Cr(VI) reduction by the biomass. The aims of the present investigation were to enhance the Cr(VI)-reducing capacity of the biomass using various chemical treatments and to elucidate the mechanisms governing Cr(VI) reduction. Among the various chemical treatments, acid-treatment showed the best performance with regards the improvement of Cr(VI) removal from the aqueous phase, while organic solvent-treatment significantly improved the removal efficiency of total Cr in the equilibrium state. Based on FTIR study, the biomass was subjected to chemical modification of its amino and carboxyl groups, to examine their roles in the Cr(VI) removal from the aqueous phase. Methylation of the amino group significantly decreased the Cr(VI) removal rate, but amination of the carboxyl group significantly increased the Cr(VI) removal rate. Meanwhile, esterification of the carboxyl group and carboxylation of the amino group decreased the Cr(VI) removal rate, but the former showed a more negative effect than the latter. These findings indicated that the amino and carboxyl groups take part in the Cr(VI) removal from the aqueous phase. In conclusion, mechanisms for direct and indirect Cr(VI) removal are proposed, and some aspects for the application of this biomass to Cr(VI) detoxification are discussed.","Studies on hexavalent chromium biosorption by chemically-treated biomass of Ecklonia sp Abs: The biomass of the brown seaweed, Ecklonia sp., is capable of reducing Cr(VI) to Cr(III). However, very little is known about the mechanism of Cr(VI) reduction by the biomass. The aims of the present investigation were to enhance the Cr(VI)-reducing capacity of the biomass using various chemical treatments and to elucidate the mechanisms governing Cr(VI) reduction. Among the various chemical treatments, acid-treatment showed the best performance with regards the improvement of Cr(VI) removal from the aqueous phase, while organic solvent-treatment significantly improved the removal efficiency of total Cr in the equilibrium state. Based on FTIR study, the biomass was subjected to chemical modification of its amino and carboxyl groups, to examine their roles in the Cr(VI) removal from the aqueous phase. Methylation of the amino group significantly decreased the Cr(VI) removal rate, but amination of the carboxyl group significantly increased the Cr(VI) removal rate. Meanwhile, esterification of the carboxyl group and carboxylation of the amino group decreased the Cr(VI) removal rate, but the former showed a more negative effect than the latter. These findings indicated that the amino and carboxyl groups take part in the Cr(VI) removal from the aqueous phase. In conclusion, mechanisms for direct and indirect Cr(VI) removal are proposed, and some aspects for the application of this biomass to Cr(VI) detoxification are discussed."
1231882,Choo et al. 2006,Accumulation of chromium (VI) from aqueous solutions using water lilies (Nymphaea spontanea),"This study describes an investigation using tropical water lilies (Nymphaea spontanea) to remove hexavalent chromium from aqueous solutions and electroplating waste. The results show that water lilies are capable of accumulating substantial amount of Cr(VI), up to 2.119 mg g(-1) from a 10 mg l(-1) solution. The roots of the plant accumulated the highest amount of Cr(VI) followed by leaves and petioles, indicating that roots play an important role in the bioremediation process. The maturity of the plant exerts a great effect on the removal and accumulation of Cr(VI). Plants of 9 weeks old accumulated the most Cr(VI) followed by those of 6 and 3 weeks old. The results also show that removal of Cr(VI) by water lilies is more efficient when the metal is present singly than in the presence of Cu(II) or in waste solution. This may be largely associated with more pronounced phytotoxicity effect on the biochemical changes in the plants and saturation of binding sites. Significant toxicity effect on the plant was evident as shown in the reduction of chlorophyll, protein and sugar contents in plants exposed to Cr(VI) in this investigation.","Accumulation of chromium (VI) from aqueous solutions using water lilies (Nymphaea spontanea) Abs: This study describes an investigation using tropical water lilies (Nymphaea spontanea) to remove hexavalent chromium from aqueous solutions and electroplating waste. The results show that water lilies are capable of accumulating substantial amount of Cr(VI), up to 2.119 mg g(-1) from a 10 mg l(-1) solution. The roots of the plant accumulated the highest amount of Cr(VI) followed by leaves and petioles, indicating that roots play an important role in the bioremediation process. The maturity of the plant exerts a great effect on the removal and accumulation of Cr(VI). Plants of 9 weeks old accumulated the most Cr(VI) followed by those of 6 and 3 weeks old. The results also show that removal of Cr(VI) by water lilies is more efficient when the metal is present singly than in the presence of Cu(II) or in waste solution. This may be largely associated with more pronounced phytotoxicity effect on the biochemical changes in the plants and saturation of binding sites. Significant toxicity effect on the plant was evident as shown in the reduction of chlorophyll, protein and sugar contents in plants exposed to Cr(VI) in this investigation."
1231881,Vatsouria et al. 2005,Anaerobic co-reduction of chromate and nitrate by bacterial cultures of Staphylococcus epidermidis L-02,"Industrial wastewater is often polluted by Cr(VI) compounds, presenting a serious environmental problem. This study addresses the removal of toxic, mutagenic Cr(VI) by means of microbial reduction to Cr(III), which can then be precipitated as oxides or hydroxides and extracted from the aquatic system. A strain of Staphylococcus epidermidis L-02 was isolated from a bacterial consortium used for the remediation of a chromate-contaminated constructed wetland system. This strain reduced Cr(VI) by using pyruvate as an electron donor under anaerobic conditions. The aims of the present study were to investigate the specific rate of Cr(VI) reduction by the strain L-02, the effects of chromate and nitrate (available as electron acceptors) on the strain, and the interference of chromate and nitrate reduction processes. The presence of Cr(VI) decreased the growth rate of the bacterium. Chromate and nitrate reduction did not occur under sterile conditions but was observed during tests with the strain L-02. The presence of nitrate increased both the specific Cr(VI) reduction rate and the cell number. Under denitrifying conditions, Cr(VI) reduction was not inhibited by nitrite, which was produced during nitrate reduction. The average specific rate of chromate reduction reached 4.4 micromol Cr 10(10 )cells(-1 )h(-1), but was only 2.0 micromol Cr 10(10 )cells(-1 )h(-1) at 20 degrees C. The maximum specific rate was as high as 8.8-9.8 micromol Cr 10(10 )cells(-1 )h(-1). The role of nitrate in chromate reduction is discussed.","Anaerobic co-reduction of chromate and nitrate by bacterial cultures of Staphylococcus epidermidis L-02 Abs: Industrial wastewater is often polluted by Cr(VI) compounds, presenting a serious environmental problem. This study addresses the removal of toxic, mutagenic Cr(VI) by means of microbial reduction to Cr(III), which can then be precipitated as oxides or hydroxides and extracted from the aquatic system. A strain of Staphylococcus epidermidis L-02 was isolated from a bacterial consortium used for the remediation of a chromate-contaminated constructed wetland system. This strain reduced Cr(VI) by using pyruvate as an electron donor under anaerobic conditions. The aims of the present study were to investigate the specific rate of Cr(VI) reduction by the strain L-02, the effects of chromate and nitrate (available as electron acceptors) on the strain, and the interference of chromate and nitrate reduction processes. The presence of Cr(VI) decreased the growth rate of the bacterium. Chromate and nitrate reduction did not occur under sterile conditions but was observed during tests with the strain L-02. The presence of nitrate increased both the specific Cr(VI) reduction rate and the cell number. Under denitrifying conditions, Cr(VI) reduction was not inhibited by nitrite, which was produced during nitrate reduction. The average specific rate of chromate reduction reached 4.4 micromol Cr 10(10 )cells(-1 )h(-1), but was only 2.0 micromol Cr 10(10 )cells(-1 )h(-1) at 20 degrees C. The maximum specific rate was as high as 8.8-9.8 micromol Cr 10(10 )cells(-1 )h(-1). The role of nitrate in chromate reduction is discussed."
1231880,Poljsak et al. 2005,Pro-oxidative vs antioxidative properties of ascorbic acid in chromium(VI)-induced damage: an in vivo and in vitro approach,"The effect of antioxidant ascorbic acid (vitamin C) pretreatment on chromium(VI)-induced damage was investigated using the yeast Saccharomyces cerevisiae as a model organism. The objective of this study was to pretreat yeast cells with the antioxidant ascorbic acid in an effort to increase cell tolerance against reactive chromium intermediates and reactive oxygen species formed during chromium(VI) reduction. Intracellular oxidation was estimated using the fluorescence indicators dihidro-2,7-dichlorofluorescein, dihydroethidium and dihydrorhodamine 123. The role of ascorbic acid pretreatment on chromium(VI) toxicity was determined by measuring mitotic gene conversion, reverse mutations, 8-OHdG, hydroxyl radical, superoxide anion and chromium(V) formation. The chromium content in the biomass was determined by flame atomic absorption spectrometry. In the absence of chromium, ascorbic acid effectively protected the cells against endogenous reactive oxygen species formed during normal cellular metabolism. In vitro measurements employing EPR and the results of supercoiled DNA cleavage revealed that the pro-oxidative action of ascorbic acid during Cr(VI) reduction was concentration-dependent and that harmful hydroxyl radical and Cr(V) had formed following Cr(VI) reduction. However, the in vivo results highlighted the important role of increased cytosol reduction capacity related to modification of Cr(V) formation, increased chromium accumulation, better scavenging ability of superoxide anions and hydrogen peroxide, and consequently decreased cytotoxicity and genotoxicity in ascorbic acid pretreated cells. Ascorbic acid influenced Cr(VI) toxicity both as a reducing agent, by decreasing Cr(V) persistence, and as an antioxidant, by decreasing intracellular superoxide anion and hydrogen peroxide formation and by quenching free radicals formed during Cr(VI) to Cr(III) reduction. Increased 8-OHdG and decreased reduced glutathione in ascorbic acid-treated cells might induce an endogenous antioxidant defense system and thus increase cell tolerance against subsequent Cr-induced stress.","Pro-oxidative vs antioxidative properties of ascorbic acid in chromium(VI)-induced damage: an in vivo and in vitro approach Abs: The effect of antioxidant ascorbic acid (vitamin C) pretreatment on chromium(VI)-induced damage was investigated using the yeast Saccharomyces cerevisiae as a model organism. The objective of this study was to pretreat yeast cells with the antioxidant ascorbic acid in an effort to increase cell tolerance against reactive chromium intermediates and reactive oxygen species formed during chromium(VI) reduction. Intracellular oxidation was estimated using the fluorescence indicators dihidro-2,7-dichlorofluorescein, dihydroethidium and dihydrorhodamine 123. The role of ascorbic acid pretreatment on chromium(VI) toxicity was determined by measuring mitotic gene conversion, reverse mutations, 8-OHdG, hydroxyl radical, superoxide anion and chromium(V) formation. The chromium content in the biomass was determined by flame atomic absorption spectrometry. In the absence of chromium, ascorbic acid effectively protected the cells against endogenous reactive oxygen species formed during normal cellular metabolism. In vitro measurements employing EPR and the results of supercoiled DNA cleavage revealed that the pro-oxidative action of ascorbic acid during Cr(VI) reduction was concentration-dependent and that harmful hydroxyl radical and Cr(V) had formed following Cr(VI) reduction. However, the in vivo results highlighted the important role of increased cytosol reduction capacity related to modification of Cr(V) formation, increased chromium accumulation, better scavenging ability of superoxide anions and hydrogen peroxide, and consequently decreased cytotoxicity and genotoxicity in ascorbic acid pretreated cells. Ascorbic acid influenced Cr(VI) toxicity both as a reducing agent, by decreasing Cr(V) persistence, and as an antioxidant, by decreasing intracellular superoxide anion and hydrogen peroxide formation and by quenching free radicals formed during Cr(VI) to Cr(III) reduction. Increased 8-OHdG and decreased reduced glutathione in ascorbic acid-treated cells might induce an endogenous antioxidant defense system and thus increase cell tolerance against subsequent Cr-induced stress."
1231878,Xu et al. 2005,Kinetics of the reduction of chromium(VI) by vitamin C,"The kinetics of the reduction of Cr(VI) to Cr(III) by vitamin C was studied using potassium dichromate solution as the model pollutant. Effects of the concentration of vitamin C, pH, temperature, and irradiation on the reduction of Cr(VI) were examined. The kinetics of Cr(VI) reduction by vitamin C can be described as -d[Cr(VI)]/dt = 0.0156 (microM s(-1).[Cr(VI)][vitamin C] (pH 5), where dt is the differential function (d) of time (t). The activation entropy (deltaS) and enthalpy (deltaH) are 42.4 kJ mol(-1) and -71.0 J mol(-1) K(-1), respectively, and the activation energy at 298 K is 63.5 kJ mol(-1). The advantages of vitamin C as a reductant are as follows: It is an important biological reductant in humans and animals, and it is not toxic. Toxic Cr(VI) can be reduced by vitamin C not only in acidic conditions but also in alkaline solutions (pH 9); furthermore, the reduction was shown to occur both under the irradiation and in the dark. The present results suggest that vitamin C could be used effectively in the remediation of Cr(VI)-contaminated soil and groundwater in a wide range of pH, with or without sunlight.","Kinetics of the reduction of chromium(VI) by vitamin C Abs: The kinetics of the reduction of Cr(VI) to Cr(III) by vitamin C was studied using potassium dichromate solution as the model pollutant. Effects of the concentration of vitamin C, pH, temperature, and irradiation on the reduction of Cr(VI) were examined. The kinetics of Cr(VI) reduction by vitamin C can be described as -d[Cr(VI)]/dt = 0.0156 (microM s(-1).[Cr(VI)][vitamin C] (pH 5), where dt is the differential function (d) of time (t). The activation entropy (deltaS) and enthalpy (deltaH) are 42.4 kJ mol(-1) and -71.0 J mol(-1) K(-1), respectively, and the activation energy at 298 K is 63.5 kJ mol(-1). The advantages of vitamin C as a reductant are as follows: It is an important biological reductant in humans and animals, and it is not toxic. Toxic Cr(VI) can be reduced by vitamin C not only in acidic conditions but also in alkaline solutions (pH 9); furthermore, the reduction was shown to occur both under the irradiation and in the dark. The present results suggest that vitamin C could be used effectively in the remediation of Cr(VI)-contaminated soil and groundwater in a wide range of pH, with or without sunlight."
1231877,Kingston et al. 2005,Determination and evaluation of hexavalent chromium in power plant coal combustion by-products and cost-effective environmental remediation solutions using acid mine drainage,"The chromium species leaching from a coal combustion fly ash landfill has been characterized as well as a novel approach to treat leachates rich in hexavalent chromium, Cr(VI), by using another natural waste by-product, acid mine drainage (AMD), has been investigated during this study. It is observed that as much as 8% (approximately 10 microg g(-1) in fly ash) of total chromium is converted to the Cr(VI) species during oxidative combustion of coal and remains in the resulting ash as a stable species, however, it is significantly mobile in water based leaching. Approximately 1.23 +/- 0.01 microg g(-1) of Cr(VI) was found in the landfill leachate from permanent deposits of aged fly ash. This study also confirmed the use of AMD, which often is in close proximity to coal combustion by-product landfills, is an extremely effective and economical remediation option for the elimination of hexavalent chromium in fly ash generated leachate. Speciated isotope dilution mass spectrometry (SIDMS), as described in EPA Method 6800, was used to analytically evaluate and validate the field application of the ferrous iron and chromate chemistry in the remediation of Cr(VI) runoff.","Determination and evaluation of hexavalent chromium in power plant coal combustion by-products and cost-effective environmental remediation solutions using acid mine drainage Abs: The chromium species leaching from a coal combustion fly ash landfill has been characterized as well as a novel approach to treat leachates rich in hexavalent chromium, Cr(VI), by using another natural waste by-product, acid mine drainage (AMD), has been investigated during this study. It is observed that as much as 8% (approximately 10 microg g(-1) in fly ash) of total chromium is converted to the Cr(VI) species during oxidative combustion of coal and remains in the resulting ash as a stable species, however, it is significantly mobile in water based leaching. Approximately 1.23 +/- 0.01 microg g(-1) of Cr(VI) was found in the landfill leachate from permanent deposits of aged fly ash. This study also confirmed the use of AMD, which often is in close proximity to coal combustion by-product landfills, is an extremely effective and economical remediation option for the elimination of hexavalent chromium in fly ash generated leachate. Speciated isotope dilution mass spectrometry (SIDMS), as described in EPA Method 6800, was used to analytically evaluate and validate the field application of the ferrous iron and chromate chemistry in the remediation of Cr(VI) runoff."
1231874,Gonzalez et al. 2005,"Natural occurrence of hexavalent chromium in the Aromas Red Sands Aquifer, California","To address increasing concerns of chromium contamination in the drinking water of Santa Cruz County, we designed a study to investigate the source(s) and spatial gradients of the chromium concentration and speciation in local aquifers. This study was catalyzed by a report (January 2001) bythe Soquel Creek Water District of elevated hexavalent chromium concentrations ranging from 6 to 36 microg L(-1), approaching the state's maximum concentration limit of 50 microg L(-1), in the Aromas Red Sands aquifer. To test the accuracy of those preliminary measurements, we collected groundwater using trace metal clean techniques from 11 sites in Santa Cruz County, including 10 from the aquifer with reportedly elevated chromium concentrations and 1 from an adjacent aquifer, the Purisima, and analyzed them fortotal chromium using inductively couple plasma mass spectrometry. Nine of the reportedly 10 contaminated sites had total chromium concentrations ranging from 5 to 39 microg L(-1), while one from the control site was below the limit of detection (0.01 microg L(-1)). We also measured the speciation of chromium at all sites using a solid supported membrane extraction coupled with graphite furnace atomic absorption spectrometry and determined that on average 84% of total chromium was Cr(VI). In addition to the groundwater analyses, a series of extractions were performed on sediment samples from both the Aromas Red Sands and Purisima aquifers. These tests were used to empirically characterize sediment trace metal (Cr, Fe, Mn) distributions in five phases providing information about the origin, availability, reactivity, and mobilization of these trace metals. Results from groundwater and sediment samples indicate that the chromium is naturally occurring in the Aromas Red Sands aquifer, possibly by Cr(III) mineral deposits being oxidized to Cr(VI) by manganese oxides in the aquifer.","Natural occurrence of hexavalent chromium in the Aromas Red Sands Aquifer, California Abs: To address increasing concerns of chromium contamination in the drinking water of Santa Cruz County, we designed a study to investigate the source(s) and spatial gradients of the chromium concentration and speciation in local aquifers. This study was catalyzed by a report (January 2001) bythe Soquel Creek Water District of elevated hexavalent chromium concentrations ranging from 6 to 36 microg L(-1), approaching the state's maximum concentration limit of 50 microg L(-1), in the Aromas Red Sands aquifer. To test the accuracy of those preliminary measurements, we collected groundwater using trace metal clean techniques from 11 sites in Santa Cruz County, including 10 from the aquifer with reportedly elevated chromium concentrations and 1 from an adjacent aquifer, the Purisima, and analyzed them fortotal chromium using inductively couple plasma mass spectrometry. Nine of the reportedly 10 contaminated sites had total chromium concentrations ranging from 5 to 39 microg L(-1), while one from the control site was below the limit of detection (0.01 microg L(-1)). We also measured the speciation of chromium at all sites using a solid supported membrane extraction coupled with graphite furnace atomic absorption spectrometry and determined that on average 84% of total chromium was Cr(VI). In addition to the groundwater analyses, a series of extractions were performed on sediment samples from both the Aromas Red Sands and Purisima aquifers. These tests were used to empirically characterize sediment trace metal (Cr, Fe, Mn) distributions in five phases providing information about the origin, availability, reactivity, and mobilization of these trace metals. Results from groundwater and sediment samples indicate that the chromium is naturally occurring in the Aromas Red Sands aquifer, possibly by Cr(III) mineral deposits being oxidized to Cr(VI) by manganese oxides in the aquifer."
1231873,Hossain 2006,Graphical estimation of the dual-enzyme kinetic parameters for Cr(VI) reduction,"Chromium(VI) (Cr(VI)) contamination of soil and groundwater is a major environmental concern. Bioreduction of Cr(VI) by Shewanella oneidensis MR-1 (MR-1) can be considered a feasible option to reduce the toxic and mobile Cr(VI) to the less toxic and less mobile chromium(III) (Cr(III)). The reaction rate expression for Cr(VI) reduction is nonlinear and the rate constants are evaluated by employing nonlinear optimization techniques. The outcome of the optimization techniques, in general, depends on the initial estimate of the kinetic parameters which is not always available. A graphical approach based on sound mathematical reasoning has been developed which is accurate, simpler to use, and can provide the best initial estimate for nonlinear optimization.","Graphical estimation of the dual-enzyme kinetic parameters for Cr(VI) reduction Abs: Chromium(VI) (Cr(VI)) contamination of soil and groundwater is a major environmental concern. Bioreduction of Cr(VI) by Shewanella oneidensis MR-1 (MR-1) can be considered a feasible option to reduce the toxic and mobile Cr(VI) to the less toxic and less mobile chromium(III) (Cr(III)). The reaction rate expression for Cr(VI) reduction is nonlinear and the rate constants are evaluated by employing nonlinear optimization techniques. The outcome of the optimization techniques, in general, depends on the initial estimate of the kinetic parameters which is not always available. A graphical approach based on sound mathematical reasoning has been developed which is accurate, simpler to use, and can provide the best initial estimate for nonlinear optimization."
1231872,de Souza E Silva et al. 2006,Extraction and recovery of chromium from electroplating sludge,"This work reports a study of the extraction and recovery of chromium from the wastes (class I dangerous) generated by a galvanic manufacturer. Commercial HCl at room temperature was employed, and the conditions of the extraction process were optimized according to a sequential experimental design, which also included the acid concentration and contact time as variables. The best extraction conditions (80% v/v; 30 min; 97.6% Cr) for the chromic sludge were chosen in order to make the recovery process economically feasible. After each extraction, the residue was submitted to leaching essays, to assess environmental risks. It was found that sludge could be characterized as no longer dangerous. In the recovery study, a simple and low-cost technique was evaluated for selectivity based on an oxidation step with hydrogen peroxide. A 2(3) factorial design to assess the influence of oxidation time (min), temperature ( degrees C) and peroxide amount (mol/L) was employed. The best conditions, yielding a chromium recovery of about 92%, were a time of 60 min, a temperature of 60 degrees C and 2.1 mol/L peroxide. Additional essays revealed that the same result could be obtained with more economic conditions (40 min, 1.4 mol/L peroxide and 60 degrees C). This technique proved not only effective in comparison with existing alternatives, but also low costing.","Extraction and recovery of chromium from electroplating sludge Abs: This work reports a study of the extraction and recovery of chromium from the wastes (class I dangerous) generated by a galvanic manufacturer. Commercial HCl at room temperature was employed, and the conditions of the extraction process were optimized according to a sequential experimental design, which also included the acid concentration and contact time as variables. The best extraction conditions (80% v/v; 30 min; 97.6% Cr) for the chromic sludge were chosen in order to make the recovery process economically feasible. After each extraction, the residue was submitted to leaching essays, to assess environmental risks. It was found that sludge could be characterized as no longer dangerous. In the recovery study, a simple and low-cost technique was evaluated for selectivity based on an oxidation step with hydrogen peroxide. A 2(3) factorial design to assess the influence of oxidation time (min), temperature ( degrees C) and peroxide amount (mol/L) was employed. The best conditions, yielding a chromium recovery of about 92%, were a time of 60 min, a temperature of 60 degrees C and 2.1 mol/L peroxide. Additional essays revealed that the same result could be obtained with more economic conditions (40 min, 1.4 mol/L peroxide and 60 degrees C). This technique proved not only effective in comparison with existing alternatives, but also low costing."
1231870,Pandey et al. 2005,Antioxidative responses in relation to growth of mustard (Brassica juncea cv. Pusa Jaikisan) plants exposed to hexavalent chromium,"Effect of hexavalent chromium (Cr6+) was seen on Brassica juncea cv. Pusa Jaikisan grown for 15 days in hydroponic culture supplemented with 0.2, 2 and 20 microM Cr. The inhibitory response of Cr6+ on growth of B. juncea was concentration and time dependent. The stimulation of plant growth, observed in response to exposure to 0.2 microM Cr6+, during initial 5 days was reversed on prolonged treatment and at higher Cr6+ concentrations (2 and 20 microM Cr6+). Despite reduction in growth, chlorophyll content increased substantially on 15 days exposure to 20 microM Cr6+. Significant increases in lipid peroxidation and tissue concentration of H2O2 occurred in plants exposed to 2 and 20 microM Cr6+. Effect of Cr6+ on antioxidative enzymes in roots and leaves was differential. SOD and CAT activities at lower levels of Cr6+ supply remained higher all through the treatment. While APX was very susceptible to excess Cr6+, GR and GST increased at elevated levels of Cr6+. The results suggested Cr6+ induced depression in plant growth of B. juncea to be a function of increased cellular accumulation of Cr despite increase in the activities of some of the antioxidative enzymes.","Antioxidative responses in relation to growth of mustard (Brassica juncea cv. Pusa Jaikisan) plants exposed to hexavalent chromium Abs: Effect of hexavalent chromium (Cr6+) was seen on Brassica juncea cv. Pusa Jaikisan grown for 15 days in hydroponic culture supplemented with 0.2, 2 and 20 microM Cr. The inhibitory response of Cr6+ on growth of B. juncea was concentration and time dependent. The stimulation of plant growth, observed in response to exposure to 0.2 microM Cr6+, during initial 5 days was reversed on prolonged treatment and at higher Cr6+ concentrations (2 and 20 microM Cr6+). Despite reduction in growth, chlorophyll content increased substantially on 15 days exposure to 20 microM Cr6+. Significant increases in lipid peroxidation and tissue concentration of H2O2 occurred in plants exposed to 2 and 20 microM Cr6+. Effect of Cr6+ on antioxidative enzymes in roots and leaves was differential. SOD and CAT activities at lower levels of Cr6+ supply remained higher all through the treatment. While APX was very susceptible to excess Cr6+, GR and GST increased at elevated levels of Cr6+. The results suggested Cr6+ induced depression in plant growth of B. juncea to be a function of increased cellular accumulation of Cr despite increase in the activities of some of the antioxidative enzymes."
1231869,Pal et al. 2005,Reduction of hexavalent chromium by cell-free extract of Bacillus sphaericus AND 303 isolated from serpentine soil,"Cell-free extracts (CFEs) of chromium-resistant bacterium Bacillus sphaericus AND 303 isolated from serpentine soil of Andaman, India reduced Cr(VI) in in vitro condition, and the reductase activity was solely localized in the soluble cell-fractions (S12, S32, and S150). The enzyme was constitutive as the CFEs from cells grown in Cr(VI)-free and Cr(VI)-containing media reduced a more or less equal amount of Cr(VI). Optimum Cr(VI) reductase activity was obtained at an enzyme (S150) concentration equivalent to 4.56 mg protein/mL, 300 microM: Cr(VI) and pH 6.0 after 30 min incubation at 30 degrees C. The enzyme was heat labile; 80% of its activity was lost when exposed at 70 degrees C for 15 min. Kinetics of Cr(VI) reductase activity fit well with the linearized Lineweaver-Burk plot and showed a V(max) of 1.432 micromol Cr(VI)/mg protein/min and K(m) of 158.12 microM: Cr(VI). The presence of additional electron donors accelerated Cr(VI) reductase activity of CFE, and an increase of 28% activity over control was recorded with 1.0 microM: NADH. Heavy metal ions such as Ni(II), Cu(II), and Cd(II) were strong inhibitors of Cr(VI) reductase unlike that of 100 microM: Co(II), which retained 93% activity over control.","Reduction of hexavalent chromium by cell-free extract of Bacillus sphaericus AND 303 isolated from serpentine soil Abs: Cell-free extracts (CFEs) of chromium-resistant bacterium Bacillus sphaericus AND 303 isolated from serpentine soil of Andaman, India reduced Cr(VI) in in vitro condition, and the reductase activity was solely localized in the soluble cell-fractions (S12, S32, and S150). The enzyme was constitutive as the CFEs from cells grown in Cr(VI)-free and Cr(VI)-containing media reduced a more or less equal amount of Cr(VI). Optimum Cr(VI) reductase activity was obtained at an enzyme (S150) concentration equivalent to 4.56 mg protein/mL, 300 microM: Cr(VI) and pH 6.0 after 30 min incubation at 30 degrees C. The enzyme was heat labile; 80% of its activity was lost when exposed at 70 degrees C for 15 min. Kinetics of Cr(VI) reductase activity fit well with the linearized Lineweaver-Burk plot and showed a V(max) of 1.432 micromol Cr(VI)/mg protein/min and K(m) of 158.12 microM: Cr(VI). The presence of additional electron donors accelerated Cr(VI) reductase activity of CFE, and an increase of 28% activity over control was recorded with 1.0 microM: NADH. Heavy metal ions such as Ni(II), Cu(II), and Cd(II) were strong inhibitors of Cr(VI) reductase unlike that of 100 microM: Co(II), which retained 93% activity over control."
1231868,Russo et al. 2005,Molecular mechanisms of hexavalent chromium-induced apoptosis in human bronchoalveolar cells,"Hexavalent chromium (Cr[VI]) is classified by the International Agency for Research on Cancer as a group I carcinogen. Although the U.S. Occupational Safety and Health Administration was obliged to reduce the permissible exposure limit (PEL), it was reported that U.S. workers continue to be exposed to dangerously high Cr(VI) levels. In this study, we examined the role of p53 and target genes in a bronchoalveolar carcinoma isogenic cell line system and in primary human bronchial epithelial cells. p53-Negative parental H358 cell line, the same line in which the wild-type p53 expression vector (pC53-SN3) was introduced, and cells obtained from biopsies of human bronchus were exposed to chromate. Induction of DNA strand breaks were evaluated by alkaline elution assay, and apoptosis was analyzed by gel ladder, annexin V-PI staining, and ELISA, whereas p53 and target genes were evaluated by Western blots. Although Cr(VI) induced DNA strand breaks in both H358 cell clones, apoptosis was present only in the p53-transfected cells (H358p53(+/+)). In these cells, Cr(VI)-induced apoptosis is mediated by p53 upregulation of p53-upregulated modulator of apoptosis (PUMA), BAX translocation to mitochondria, cytochrome c release, and caspase-3 activation. In primary human bronchial epithelial cells expressing functional p53, Cr(VI) induced expression of PUMA and Noxa, which promote apoptosis through BAX. This result establishes p53 as the &quot;necessary&quot; player in Cr(VI)-induced apoptosis. To the best of our knowledge, this is the first report indicating strict correlation of Cr(VI) apoptosis to PUMA induction on primary human bronchoalveolar cells in short-term cultures.","Molecular mechanisms of hexavalent chromium-induced apoptosis in human bronchoalveolar cells Abs: Hexavalent chromium (Cr[VI]) is classified by the International Agency for Research on Cancer as a group I carcinogen. Although the U.S. Occupational Safety and Health Administration was obliged to reduce the permissible exposure limit (PEL), it was reported that U.S. workers continue to be exposed to dangerously high Cr(VI) levels. In this study, we examined the role of p53 and target genes in a bronchoalveolar carcinoma isogenic cell line system and in primary human bronchial epithelial cells. p53-Negative parental H358 cell line, the same line in which the wild-type p53 expression vector (pC53-SN3) was introduced, and cells obtained from biopsies of human bronchus were exposed to chromate. Induction of DNA strand breaks were evaluated by alkaline elution assay, and apoptosis was analyzed by gel ladder, annexin V-PI staining, and ELISA, whereas p53 and target genes were evaluated by Western blots. Although Cr(VI) induced DNA strand breaks in both H358 cell clones, apoptosis was present only in the p53-transfected cells (H358p53(+/+)). In these cells, Cr(VI)-induced apoptosis is mediated by p53 upregulation of p53-upregulated modulator of apoptosis (PUMA), BAX translocation to mitochondria, cytochrome c release, and caspase-3 activation. In primary human bronchial epithelial cells expressing functional p53, Cr(VI) induced expression of PUMA and Noxa, which promote apoptosis through BAX. This result establishes p53 as the &quot;necessary&quot; player in Cr(VI)-induced apoptosis. To the best of our knowledge, this is the first report indicating strict correlation of Cr(VI) apoptosis to PUMA induction on primary human bronchoalveolar cells in short-term cultures."
1231867,Su and  Ludwig 2005,Treatment of hexavalent chromium in chromite ore processing solid waste using a mixed reductant solution of ferrous sulfate and sodium dithionite,"We investigated a method for delivering ferrous iron into the subsurface to enhance chemical reduction of Cr(VI) in chromite ore processing solid waste (COPSW) derived from the production of ferrochrome alloy. The COPSW is characterized by high pH (8.5-11.5) and high Cr(VI) concentrations in the solid phase (up to 550 mg kg(-1)) and dissolved phase (3-57 mg L(-1)). The dominant solid-phase minerals are forsterite (Mg2SiO4), brucite (Mg-(OH)2), and hydrocalumite [Ca4(Al, Fe)2(OH)12X x 6H2O), X = (OH)2(2-), SO4(2-), CrO4(2-)]. The method utilizes FeSO4 in combination with Na2S2O4 to inhibit oxidation and precipitation of the ferrous iron, thereby preventing well and formation clogging. Laboratory batch tests using a 0.05 M FeSO4 + 0.05 M Na2S2O4 solution indicated effective treatment of both dissolved and solid-phase Cr(VI). Contrary to treatments with FeSO4 and FeCl2 alone, the combination resulted in both complete removal of Cr(VI) from solution and sustained Fe(ll) concentrations in solution after a 24 h period. A field test involving injection of 5700 L of a 0.07 M FeSO4 + 0.07 M Na2S2O4 solution into a COPSW saturated zone (pH 11.5) indicated no well and formation clogging during injection. Examination of a core collected 0.46 m from the injection well following injection indicated effective treatment of the solid phase Cr(VI) based on analysis of water, phosphate solution, and high temperature alkaline extracts. The combined reductant solution also imparted a residual treatment capacity to the COPSW allowing for subsequent treatment of dissolved phase Cr(VI); however, dissemination of the iron in the highly alkaline environment appeared to be impeded by the inability to sufficiently lower the pH with distance from the injection well to avoid precipitation of Fe(OH)2 and likely also FeCO3. Injection of a 0.2 M FeSO4 + 0.2 M Na2S2O4 solution into another COPSW saturated zone (pH 9) indicated much more effective dissemination of the injected iron.","Treatment of hexavalent chromium in chromite ore processing solid waste using a mixed reductant solution of ferrous sulfate and sodium dithionite Abs: We investigated a method for delivering ferrous iron into the subsurface to enhance chemical reduction of Cr(VI) in chromite ore processing solid waste (COPSW) derived from the production of ferrochrome alloy. The COPSW is characterized by high pH (8.5-11.5) and high Cr(VI) concentrations in the solid phase (up to 550 mg kg(-1)) and dissolved phase (3-57 mg L(-1)). The dominant solid-phase minerals are forsterite (Mg2SiO4), brucite (Mg-(OH)2), and hydrocalumite [Ca4(Al, Fe)2(OH)12X x 6H2O), X = (OH)2(2-), SO4(2-), CrO4(2-)]. The method utilizes FeSO4 in combination with Na2S2O4 to inhibit oxidation and precipitation of the ferrous iron, thereby preventing well and formation clogging. Laboratory batch tests using a 0.05 M FeSO4 + 0.05 M Na2S2O4 solution indicated effective treatment of both dissolved and solid-phase Cr(VI). Contrary to treatments with FeSO4 and FeCl2 alone, the combination resulted in both complete removal of Cr(VI) from solution and sustained Fe(ll) concentrations in solution after a 24 h period. A field test involving injection of 5700 L of a 0.07 M FeSO4 + 0.07 M Na2S2O4 solution into a COPSW saturated zone (pH 11.5) indicated no well and formation clogging during injection. Examination of a core collected 0.46 m from the injection well following injection indicated effective treatment of the solid phase Cr(VI) based on analysis of water, phosphate solution, and high temperature alkaline extracts. The combined reductant solution also imparted a residual treatment capacity to the COPSW allowing for subsequent treatment of dissolved phase Cr(VI); however, dissemination of the iron in the highly alkaline environment appeared to be impeded by the inability to sufficiently lower the pH with distance from the injection well to avoid precipitation of Fe(OH)2 and likely also FeCO3. Injection of a 0.2 M FeSO4 + 0.2 M Na2S2O4 solution into another COPSW saturated zone (pH 9) indicated much more effective dissemination of the injected iron."
1231866,Sun et al. 2005,Visible light Cr(VI) reduction and organic chemical oxidation by TiO2 photocatalysis,"Here we report the simultaneous Cr(VI) reduction and 4-chlorophenol (4-CP) oxidation in water under visible light (wavelength &gt; 400 nm) using commercial Degussa P25 TiO2. This remarkable observation was attributed to a synergistic effect among TiO2, Cr(VI), and 4-CP. It is well known that TiO2 alone cannot remove either 4-CP or Cr(VI) efficiently under visible light. Moreover, the interaction between Cr(VI) and 4-CP is minimal if not negligible. However, we found that the combination of TiO2, Cr(VI), and 4-CP together can enable efficient Cr(VI) reduction and 4-CP oxidation under visible light. The specific roles of the three ingredients in the synergistic system were studied parametrically. It was found that optimal concentrations of Cr(VI) and TiO2 exist for the Cr(VI) reduction and 4-CP oxidation. Cr(VI) was compared experimentally with other metals such as Cu(ll), Fe(lll), Mn(IV), Ce(IV), and V(V). Among all these metal ions, only Cr(VI) promotes the photocatalytic oxidation of 4-CP. The amount of 4-CP removed was directly related to the initial concentration of Cr(VI). The system was also tested with four other chemicals (aniline, salicylic acid, formic acid, and diethyl phosphoramidate). We found that the same phenomenon occurred for organics containing acid and/or phenolic groups. Cr(VI) was reduced at the same time as the organic chemicals being oxidized during photoreaction under visible light. The synergistic effect was also found with pure anatase TiO2 and rutile TiO2. This study demonstrates a possible economical way for environmental cleanup under visible light.","Visible light Cr(VI) reduction and organic chemical oxidation by TiO2 photocatalysis Abs: Here we report the simultaneous Cr(VI) reduction and 4-chlorophenol (4-CP) oxidation in water under visible light (wavelength &gt; 400 nm) using commercial Degussa P25 TiO2. This remarkable observation was attributed to a synergistic effect among TiO2, Cr(VI), and 4-CP. It is well known that TiO2 alone cannot remove either 4-CP or Cr(VI) efficiently under visible light. Moreover, the interaction between Cr(VI) and 4-CP is minimal if not negligible. However, we found that the combination of TiO2, Cr(VI), and 4-CP together can enable efficient Cr(VI) reduction and 4-CP oxidation under visible light. The specific roles of the three ingredients in the synergistic system were studied parametrically. It was found that optimal concentrations of Cr(VI) and TiO2 exist for the Cr(VI) reduction and 4-CP oxidation. Cr(VI) was compared experimentally with other metals such as Cu(ll), Fe(lll), Mn(IV), Ce(IV), and V(V). Among all these metal ions, only Cr(VI) promotes the photocatalytic oxidation of 4-CP. The amount of 4-CP removed was directly related to the initial concentration of Cr(VI). The system was also tested with four other chemicals (aniline, salicylic acid, formic acid, and diethyl phosphoramidate). We found that the same phenomenon occurred for organics containing acid and/or phenolic groups. Cr(VI) was reduced at the same time as the organic chemicals being oxidized during photoreaction under visible light. The synergistic effect was also found with pure anatase TiO2 and rutile TiO2. This study demonstrates a possible economical way for environmental cleanup under visible light."
1231865,Qin et al. 2005,"Hexavalent chromium removal by reduction with ferrous sulfate, coagulation, and filtration: a pilot-scale study","A flow-through pilot-scale system was tested for removal of Cr(VI) from contaminated groundwater in Glendale, California. The process consisted of the reduction of Cr(VI) to Cr(lll) using ferrous sulfate followed by coagulation and filtration. Results indicated that the technology could reduce influent Cr(VI) concentrations of 100 microg L(-1) to below detectable levels and also remove total Cr (Cr(VI) plus Cr(lll)) to very low concentrations (&lt; 5 microg L(-1)) under optimized conditions. Complete reduction of Cr(VI) to Cr(lll) was accomplished with Fe(ll) doses of 10-50 times the Cr(Vl) concentration even in the presence of significant dissolved oxygen levels. The overall Cr removal efficiency was largely determined by the filterability of Cr(lll) and Fe(lll) precipitates, of which a relatively high filtration pH (7.5-7.6) and high filter loading rate (6 gpm ft(-2)) had negative impacts. The pilot system was able to operate for an extended time period (23-46 h depending on the Fe:Cr mass ratio) before turbidity breakthrough or high head loss. Backwash water was effectively settled with low doses (0.2-1.0 mg L(-1)) of high molecular weight polymer. Backwash solids were found to be nonhazardous bythe toxicity characteristic leaching procedure but hazardous by the California waste extraction test.","Hexavalent chromium removal by reduction with ferrous sulfate, coagulation, and filtration: a pilot-scale study Abs: A flow-through pilot-scale system was tested for removal of Cr(VI) from contaminated groundwater in Glendale, California. The process consisted of the reduction of Cr(VI) to Cr(lll) using ferrous sulfate followed by coagulation and filtration. Results indicated that the technology could reduce influent Cr(VI) concentrations of 100 microg L(-1) to below detectable levels and also remove total Cr (Cr(VI) plus Cr(lll)) to very low concentrations (&lt; 5 microg L(-1)) under optimized conditions. Complete reduction of Cr(VI) to Cr(lll) was accomplished with Fe(ll) doses of 10-50 times the Cr(Vl) concentration even in the presence of significant dissolved oxygen levels. The overall Cr removal efficiency was largely determined by the filterability of Cr(lll) and Fe(lll) precipitates, of which a relatively high filtration pH (7.5-7.6) and high filter loading rate (6 gpm ft(-2)) had negative impacts. The pilot system was able to operate for an extended time period (23-46 h depending on the Fe:Cr mass ratio) before turbidity breakthrough or high head loss. Backwash water was effectively settled with low doses (0.2-1.0 mg L(-1)) of high molecular weight polymer. Backwash solids were found to be nonhazardous bythe toxicity characteristic leaching procedure but hazardous by the California waste extraction test."
1231864,Shrivastava et al. 2005,Effects of dengue virus infection on peripheral blood cells of mice exposed to hexavalent chromium with drinking water,"<strong>BACKGROUND & OBJECTIVE: </strong>The occupational and non-occupational exposure to hexavalent chromium Cr (VI) is common. The effect of chromium compromises the immune response of the host. Dengue virus (DV) infection causes various changes in the peripheral blood cells. It is, therefore, possible that the chromium toxicity may affect the disease process during DV infection. The present study aims to study the effects of dengue virus infection on peripheral blood cells of mice fed Cr (VI) with drinking water.<br /><br /><strong>METHODS: </strong>One group of mice was given ad libitum drinking water containing Cr (VI) and the other group used as the normal control mice was given plain water to drink. At the 3, 6 and 9 wk of Cr (VI) drinking, a set of mice from each group was inoculated intracerebrally (ic) with DV and studied at the 4th and 8th day post inoculation.<br /><br /><strong>RESULTS: </strong>It was observed that Cr (VI) drinking led to reduction in lymphocytes, haemoglobin and the haematocrit values while the granulocyte, monocyte and platelet counts were increased. On the other hand, most of the parameters were decreased following inoculation of normal mice with DV. In Cr (VI)-fed mice the effects of DV infection were minimal. The most significant finding of these experiments was that the reduction in platelet counts following inoculation with DV was markedly less in Cr (VI)-fed mice than that in DV-inoculated normal control mice.<br /><br /><strong>INTERPRETATION & CONCLUSION: </strong>Cr(VI) compounds have been declared as a potent occupational carcinogen. On the contrary, Cr(III) salts such as chromium polynicotinate, chromium chloride and chromium picolinate, are used as micronutrients and nutritional supplements, and have been shown to exhibit health benefits in animals and humans. Whether therapeutic doses of chromium (III) compounds may be able to prevent the DV-induced fall in platelet counts, needs to be investigated.","Effects of dengue virus infection on peripheral blood cells of mice exposed to hexavalent chromium with drinking water Abs: <strong>BACKGROUND & OBJECTIVE: </strong>The occupational and non-occupational exposure to hexavalent chromium Cr (VI) is common. The effect of chromium compromises the immune response of the host. Dengue virus (DV) infection causes various changes in the peripheral blood cells. It is, therefore, possible that the chromium toxicity may affect the disease process during DV infection. The present study aims to study the effects of dengue virus infection on peripheral blood cells of mice fed Cr (VI) with drinking water.<br /><br /><strong>METHODS: </strong>One group of mice was given ad libitum drinking water containing Cr (VI) and the other group used as the normal control mice was given plain water to drink. At the 3, 6 and 9 wk of Cr (VI) drinking, a set of mice from each group was inoculated intracerebrally (ic) with DV and studied at the 4th and 8th day post inoculation.<br /><br /><strong>RESULTS: </strong>It was observed that Cr (VI) drinking led to reduction in lymphocytes, haemoglobin and the haematocrit values while the granulocyte, monocyte and platelet counts were increased. On the other hand, most of the parameters were decreased following inoculation of normal mice with DV. In Cr (VI)-fed mice the effects of DV infection were minimal. The most significant finding of these experiments was that the reduction in platelet counts following inoculation with DV was markedly less in Cr (VI)-fed mice than that in DV-inoculated normal control mice.<br /><br /><strong>INTERPRETATION & CONCLUSION: </strong>Cr(VI) compounds have been declared as a potent occupational carcinogen. On the contrary, Cr(III) salts such as chromium polynicotinate, chromium chloride and chromium picolinate, are used as micronutrients and nutritional supplements, and have been shown to exhibit health benefits in animals and humans. Whether therapeutic doses of chromium (III) compounds may be able to prevent the DV-induced fall in platelet counts, needs to be investigated."
1231863,Niu et al. 2005,Removal of hexavalent chromium from aqueous solution by iron nanoparticles,"Groundwater remediation by nanoparticles has received increasing interest in recent years. This report presents a thorough evaluation of hexavalent chromium removal in aqueous solutions using iron (Fe(0)) nanoparticles. Cr(VI) is a major pollutant of groundwater. Zero-valent iron, an important natural reductant of Cr(VI), is an option in the remediation of contaminated sites, transforming Cr(VI) to essentially nontoxic Cr(III). At a dose of 0.4 g/L, 100% of Cr(VI) (20 mg/L) was degraded. The Cr(VI) removal efficiency decreased significantly with increasing initial pH. Different Fe(0) type was compared in the same conditions. The reactivity was in the order starch-stabilized Fe(0) nanoparticles&gt;Fe(0) nanoparticles&gt;Fe(0) powder&gt;Fe(0) filings. Electrochemical analysis of the reaction process led to the conclusion that Cr(OH)(3) should be the final product of Cr(VI). Iron nanoparticles are good choice for the remediation of heavy metals in groundwater.","Removal of hexavalent chromium from aqueous solution by iron nanoparticles Abs: Groundwater remediation by nanoparticles has received increasing interest in recent years. This report presents a thorough evaluation of hexavalent chromium removal in aqueous solutions using iron (Fe(0)) nanoparticles. Cr(VI) is a major pollutant of groundwater. Zero-valent iron, an important natural reductant of Cr(VI), is an option in the remediation of contaminated sites, transforming Cr(VI) to essentially nontoxic Cr(III). At a dose of 0.4 g/L, 100% of Cr(VI) (20 mg/L) was degraded. The Cr(VI) removal efficiency decreased significantly with increasing initial pH. Different Fe(0) type was compared in the same conditions. The reactivity was in the order starch-stabilized Fe(0) nanoparticles&gt;Fe(0) nanoparticles&gt;Fe(0) powder&gt;Fe(0) filings. Electrochemical analysis of the reaction process led to the conclusion that Cr(OH)(3) should be the final product of Cr(VI). Iron nanoparticles are good choice for the remediation of heavy metals in groundwater."
1231862,Rocchetta et al. 2006,Effect of chromium on the fatty acid composition of two strains of Euglena gracilis,"The effect of hexavalent chromium on fatty acid composition was studied in two strains of Euglena gracilis; UTEX 753 (from the Culture Collection of Algae of Texas University, USA) and MAT (isolated from a highly polluted River). Both were grown in photoauxotrophic and photoheterotrophic conditions and exposed to two metal concentrations, one below and one above IC50. The high malondialdehyde (MDA) levels (3 to 7-fold) obtained with chromium concentration above IC50, suggested the existence of metal-induced lipid peroxidation. Total lipid content increased only with concentration below IC50, whereas it was inhibited by higher metal concentration. Photoheterotrophic control strains exhibited a significantly higher proportion of saturated and polyunsaturated fatty acids. Polyunsaturated acids were most affected by chromium, especially those related to chloroplast structures. Ultra-structure studies showed clear thylakoid disorganization in all treated cells. The results indicate that hexavalent chromium affects levels of fatty acids, especially those related to photosynthetic activity.","Effect of chromium on the fatty acid composition of two strains of Euglena gracilis Abs: The effect of hexavalent chromium on fatty acid composition was studied in two strains of Euglena gracilis; UTEX 753 (from the Culture Collection of Algae of Texas University, USA) and MAT (isolated from a highly polluted River). Both were grown in photoauxotrophic and photoheterotrophic conditions and exposed to two metal concentrations, one below and one above IC50. The high malondialdehyde (MDA) levels (3 to 7-fold) obtained with chromium concentration above IC50, suggested the existence of metal-induced lipid peroxidation. Total lipid content increased only with concentration below IC50, whereas it was inhibited by higher metal concentration. Photoheterotrophic control strains exhibited a significantly higher proportion of saturated and polyunsaturated fatty acids. Polyunsaturated acids were most affected by chromium, especially those related to chloroplast structures. Ultra-structure studies showed clear thylakoid disorganization in all treated cells. The results indicate that hexavalent chromium affects levels of fatty acids, especially those related to photosynthetic activity."
1231861,Dweck et al. 2005,Hexavalent chromium study's conclusions unjustified,,Hexavalent chromium study's conclusions unjustified Abs: 
1231860,Yousef et al. 2006,Ameliorating effect of folic acid on chromium(VI)-induced changes in reproductive performance and seminal plasma biochemistry in male rabbits,"Chromium hexavalent (Cr(VI)) is a biologically active oxidized state of chromium. It is involved in the redox cycle, with the production of reactive oxygen species. Free radical scavenging properties and possible antioxidant activity of folic acid (FA) have been reported; therefore, the present study examined possible protective effects of FA on the reproductive toxicity of potassium dichromate (K2Cr2O7) in male New Zealand white rabbits. We monitored reproductive performance, lipid peroxidation, enzyme activities and biochemical parameters in seminal plasma. Six rabbits per treatment group (and a control group) were exposed: 8.3 microg/kg FA; 5 mg/kg potassium dichromate (contains 3.6 mg chromium(VI)) and 5 mg/kg potassium dichromate+8.3 microg/kg FA. Results showed that semen quality deteriorated following potassium dichromate exposure. Testosterone levels, body weight (BW), relative weights of testes (RTW) and epididymis (REW) all decreased. Levels of thiobarbituric acid-reactive substances increased, whereas the activities of glutathione S-transferase, transaminases and phosphatases decreased in the seminal plasma. FA alone significantly increased BW, RTW, REW, semen characteristics and seminal plasma enzymes, and decreased the levels of free radicals. Furthermore, FA can be effective in the protection of chromium-induced reproductive toxicity.","Ameliorating effect of folic acid on chromium(VI)-induced changes in reproductive performance and seminal plasma biochemistry in male rabbits Abs: Chromium hexavalent (Cr(VI)) is a biologically active oxidized state of chromium. It is involved in the redox cycle, with the production of reactive oxygen species. Free radical scavenging properties and possible antioxidant activity of folic acid (FA) have been reported; therefore, the present study examined possible protective effects of FA on the reproductive toxicity of potassium dichromate (K2Cr2O7) in male New Zealand white rabbits. We monitored reproductive performance, lipid peroxidation, enzyme activities and biochemical parameters in seminal plasma. Six rabbits per treatment group (and a control group) were exposed: 8.3 microg/kg FA; 5 mg/kg potassium dichromate (contains 3.6 mg chromium(VI)) and 5 mg/kg potassium dichromate+8.3 microg/kg FA. Results showed that semen quality deteriorated following potassium dichromate exposure. Testosterone levels, body weight (BW), relative weights of testes (RTW) and epididymis (REW) all decreased. Levels of thiobarbituric acid-reactive substances increased, whereas the activities of glutathione S-transferase, transaminases and phosphatases decreased in the seminal plasma. FA alone significantly increased BW, RTW, REW, semen characteristics and seminal plasma enzymes, and decreased the levels of free radicals. Furthermore, FA can be effective in the protection of chromium-induced reproductive toxicity."
1231859,Arakawa et al. 2006,Sequence specificity of Cr(III)-DNA adduct formation in the p53 gene: NGG sequences are preferential adduct-forming sites,"Hexavalent chromium [Cr(VI)] is a known etiological factor in human lung cancer. Cr(VI) exposure-related lung cancer has a high mutation incidence in the p53 gene. Upon intake in human cells Cr(VI) is reduced to Cr(III), which is able to conjugate with amino acids and consequently form either binary Cr(III)-DNA or ternary Cr(III)-amino acid-DNA adducts. Both binary and ternary Cr(III)-DNA adducts are mutagenic. We have found that the Escherichia coli nucleotide excision enzyme UvrABC nuclease is able to incise Cr(III)- and Cr(III)-histidine-modified plasmid DNA and the extent of incision is proportional to the amount of Cr(III)-DNA adducts in the plasmid. In order to determine the role of Cr(III)-DNA adducts in the mutagenesis of the p53 gene in human cancer using the UvrABC nuclease incision method, we have mapped the Cr(III)-DNA distribution in PCR DNA fragments amplified from exons 5, 7 and 8 of the p53 gene. We have found that the sequence specificities of Cr(III)-DNA and Cr(III)-histidine-DNA adducts in the p53 gene sequence are identical and that both types of adducts are preferentially formed at -NGG- sequences, including codons 245, 248 and 249, the mutational hotspots in human lung cancer. It has been found that Cr(III)-DNA adducts induce mainly G to T mutations. Therefore, these results suggest that Cr(III)-DNA adduct formation contributes to the p53 gene mutations in lung carcinogenesis.","Sequence specificity of Cr(III)-DNA adduct formation in the p53 gene: NGG sequences are preferential adduct-forming sites Abs: Hexavalent chromium [Cr(VI)] is a known etiological factor in human lung cancer. Cr(VI) exposure-related lung cancer has a high mutation incidence in the p53 gene. Upon intake in human cells Cr(VI) is reduced to Cr(III), which is able to conjugate with amino acids and consequently form either binary Cr(III)-DNA or ternary Cr(III)-amino acid-DNA adducts. Both binary and ternary Cr(III)-DNA adducts are mutagenic. We have found that the Escherichia coli nucleotide excision enzyme UvrABC nuclease is able to incise Cr(III)- and Cr(III)-histidine-modified plasmid DNA and the extent of incision is proportional to the amount of Cr(III)-DNA adducts in the plasmid. In order to determine the role of Cr(III)-DNA adducts in the mutagenesis of the p53 gene in human cancer using the UvrABC nuclease incision method, we have mapped the Cr(III)-DNA distribution in PCR DNA fragments amplified from exons 5, 7 and 8 of the p53 gene. We have found that the sequence specificities of Cr(III)-DNA and Cr(III)-histidine-DNA adducts in the p53 gene sequence are identical and that both types of adducts are preferentially formed at -NGG- sequences, including codons 245, 248 and 249, the mutational hotspots in human lung cancer. It has been found that Cr(III)-DNA adducts induce mainly G to T mutations. Therefore, these results suggest that Cr(III)-DNA adduct formation contributes to the p53 gene mutations in lung carcinogenesis."
1231858,She et al. 2005,Preparation of fluorescent polyvinyl alcohol keto-derivatives nanoparticles and selective determination of chromium(VI),"A novel fluorescent polyvinyl alcohol keto-derivatives nanoparticle (PVAK) has been prepared in one-step method. The nanoparticles has excitation and emission maxima at 349 and 462 nm, respectively. Based on the fluorescence quenching of PVAK by Cr(VI), we established a simple and selective fluorimetric method for the determination of Cr(VI) without separation of Cr(III) in water. The reaction conditions between Cr(VI) and PVAK were investigated in detail. Furthermore, the reaction mechanism between PVAK and Cr(VI) was also discussed. Under optimal experimental conditions, a limit of detection of 0.02 microg mL(-1) was achieved. The calibration curve was linear over the concentration range 0.1-13.2 microg mL(-1) with a correlation coefficient of 0.9987. The proposed method has been applied to the selective quantification of Cr(VI) in synthetic samples and waste-water samples with the satisfactory results.","Preparation of fluorescent polyvinyl alcohol keto-derivatives nanoparticles and selective determination of chromium(VI) Abs: A novel fluorescent polyvinyl alcohol keto-derivatives nanoparticle (PVAK) has been prepared in one-step method. The nanoparticles has excitation and emission maxima at 349 and 462 nm, respectively. Based on the fluorescence quenching of PVAK by Cr(VI), we established a simple and selective fluorimetric method for the determination of Cr(VI) without separation of Cr(III) in water. The reaction conditions between Cr(VI) and PVAK were investigated in detail. Furthermore, the reaction mechanism between PVAK and Cr(VI) was also discussed. Under optimal experimental conditions, a limit of detection of 0.02 microg mL(-1) was achieved. The calibration curve was linear over the concentration range 0.1-13.2 microg mL(-1) with a correlation coefficient of 0.9987. The proposed method has been applied to the selective quantification of Cr(VI) in synthetic samples and waste-water samples with the satisfactory results."
1231857,Shashidhar et al. 2006,Bench-scale column experiments to study the containment of Cr(VI) in confined aquifers by bio-transformation,"Bench-scale soil column experiments were conducted to study the effectiveness of Cr(VI) containment in confined aquifers using in situ bio-transformation. Batch adsorption studies were carried out to estimate the adsorption capacities of two different soils for Cr(VI) and Cr(III). Bio-kinetic parameters were evaluated for the enriched microbial system. The inhibition constant, evaluated using Monod's inhibition model, was found to be 11.46 mg/L of Cr(VI). Transport studies indicated that it would not be possible to contain Cr(VI) by adsorption alone. Transport and bio-transformation studies indicated that the pore velocity and the initial bio-mass concentration significantly affect the containment process. In situ bio-remediation is effective in the case of silty aquifers. Cr(VI) concentration of 25 mg/L was effectively contained within 60 cm of a confined silty aquifer. Cr(VI) containment could be achieved in sandy aquifers when the pore velocity was very low and the initial augmented bio-mass was high. A bio-barrier of approximately one meter width would be able to contain Cr(VI) if the initial Cr(VI) concentration is as much as 25 mg/L.","Bench-scale column experiments to study the containment of Cr(VI) in confined aquifers by bio-transformation Abs: Bench-scale soil column experiments were conducted to study the effectiveness of Cr(VI) containment in confined aquifers using in situ bio-transformation. Batch adsorption studies were carried out to estimate the adsorption capacities of two different soils for Cr(VI) and Cr(III). Bio-kinetic parameters were evaluated for the enriched microbial system. The inhibition constant, evaluated using Monod's inhibition model, was found to be 11.46 mg/L of Cr(VI). Transport studies indicated that it would not be possible to contain Cr(VI) by adsorption alone. Transport and bio-transformation studies indicated that the pore velocity and the initial bio-mass concentration significantly affect the containment process. In situ bio-remediation is effective in the case of silty aquifers. Cr(VI) concentration of 25 mg/L was effectively contained within 60 cm of a confined silty aquifer. Cr(VI) containment could be achieved in sandy aquifers when the pore velocity was very low and the initial augmented bio-mass was high. A bio-barrier of approximately one meter width would be able to contain Cr(VI) if the initial Cr(VI) concentration is as much as 25 mg/L."
1231856,Chen et al. 2005,Automation of liquid-liquid extraction-spectrophotometry using prolonged pseudo-liquid drops and handheld CCD for speciation of Cr(VI) and Cr(III) in water samples,"A simple spectrophotometric system, based on a prolonged pseudo-liquid drop device as an optical cell and a handheld charge coupled device (CCD) as a detector, was constructed for automatic liquid-liquid extraction and spectrophotometric speciation of trace Cr(VI) and Cr(III) in water samples. A tungsten halogen lamp was used as the light source, and a laboratory-constructed T-tube with two open ends was used to form the prolonged pseudo-liquid drop inside the tube. In the medium of perchloric acid solution, Cr(VI) reacted with 1,5-diphenylcarbazide (DPC); the formed complex was automatically extracted into n-pentanol, with a preconcentration ratio of about 5. The organic phase with extracted chromium complex was then pumped through the optical cell for absorbance measurement at 548 nm. Under optimal conditions, the calibration curve was linear in the range of 7.5 - 350 microg L(-1), with a correlation coefficient of 0.9993. The limit of detection (3sigma) was 7.5 microg L(-1). That Cr(III) species cannot react with DPC, but can be oxidized to Cr(VI) prior to determination, is the basis of the speciation analysis. The proposed speciation analysis was sensitive, yet simple, labor-effective, and cost-effective. It has been preliminarily applied for the speciation of Cr(VI) and Cr(III) in spiked river and tap water samples. It can also be used for other automatic liquid-liquid extraction-spectrophotometric determinations.","Automation of liquid-liquid extraction-spectrophotometry using prolonged pseudo-liquid drops and handheld CCD for speciation of Cr(VI) and Cr(III) in water samples Abs: A simple spectrophotometric system, based on a prolonged pseudo-liquid drop device as an optical cell and a handheld charge coupled device (CCD) as a detector, was constructed for automatic liquid-liquid extraction and spectrophotometric speciation of trace Cr(VI) and Cr(III) in water samples. A tungsten halogen lamp was used as the light source, and a laboratory-constructed T-tube with two open ends was used to form the prolonged pseudo-liquid drop inside the tube. In the medium of perchloric acid solution, Cr(VI) reacted with 1,5-diphenylcarbazide (DPC); the formed complex was automatically extracted into n-pentanol, with a preconcentration ratio of about 5. The organic phase with extracted chromium complex was then pumped through the optical cell for absorbance measurement at 548 nm. Under optimal conditions, the calibration curve was linear in the range of 7.5 - 350 microg L(-1), with a correlation coefficient of 0.9993. The limit of detection (3sigma) was 7.5 microg L(-1). That Cr(III) species cannot react with DPC, but can be oxidized to Cr(VI) prior to determination, is the basis of the speciation analysis. The proposed speciation analysis was sensitive, yet simple, labor-effective, and cost-effective. It has been preliminarily applied for the speciation of Cr(VI) and Cr(III) in spiked river and tap water samples. It can also be used for other automatic liquid-liquid extraction-spectrophotometric determinations."
1231855,Wakeman et al. 2005,Involvement of the p38 MAP kinase in Cr(VI)-induced growth arrest and apoptosis,"Hexavalent chromium [Cr(VI)] is a carcinogenic genotoxin commonly found in industry and the environment. DNA damage resulting from Cr(VI) exposure triggers numerous stress responses, including activation of cell cycle checkpoints and initiation of apoptosis. Mechanisms controlling these responses, while extensively studied, have yet to be fully elucidated. Here, we demonstrate that the p38 mitogen-activated protein kinase (MAPK) is activated by Cr(VI) exposure and that inhibition of p38 function using the selective inhibitor SB203580 results in abrogation of S-phase and G2 cell cycle checkpoints in response to Cr(VI). Also, we observe that inhibition of p38 results in decreased cell survival and increased percentage of apoptotic cells following Cr(VI) treatment. Taken together, these results indicate that p38 function is critical for optimal stress response induced by Cr(VI) exposure.","Involvement of the p38 MAP kinase in Cr(VI)-induced growth arrest and apoptosis Abs: Hexavalent chromium [Cr(VI)] is a carcinogenic genotoxin commonly found in industry and the environment. DNA damage resulting from Cr(VI) exposure triggers numerous stress responses, including activation of cell cycle checkpoints and initiation of apoptosis. Mechanisms controlling these responses, while extensively studied, have yet to be fully elucidated. Here, we demonstrate that the p38 mitogen-activated protein kinase (MAPK) is activated by Cr(VI) exposure and that inhibition of p38 function using the selective inhibitor SB203580 results in abrogation of S-phase and G2 cell cycle checkpoints in response to Cr(VI). Also, we observe that inhibition of p38 results in decreased cell survival and increased percentage of apoptotic cells following Cr(VI) treatment. Taken together, these results indicate that p38 function is critical for optimal stress response induced by Cr(VI) exposure."
1231854,O'Brien et al. 2005,Nucleotide excision repair functions in the removal of chromium-induced DNA damage in mammalian cells,"Some hexavalent chromium (Cr(VI))-containing compounds are human lung carcinogens. While ample information is available on the genetic lesions produced by Cr, surprisingly little is known regarding the cellular mechanisms involved in the removal of Cr-DNA adducts. Nucleotide excision repair (NER) is a highly versatile pathway that is responsive to a variety of DNA helix-distorting lesions. Binary Cr-DNA monoadducts do not produce a significant degree of helical distortion. However, these lesions are unstable due to the propensity of Cr(III) to form DNA adducts (DNA interstrand crosslinks, DNA-protein/amino acid ternary adducts) which may serve as substrates for NER. Therefore, the focus of this study was to determine the role of NER in the processing of Cr-DNA damage using normal (CHO-AA8) and NER-deficient [UV-5 (XP-D); UV-41 (ERCC4/XP-F)] hamster cells. We found that both UV-5 and UV-41 cells exhibited an increased sensitivity towards Cr(VI)-induced clonogenic lethality relative to AA8 cells and were completely deficient in the removal of Cr-DNA adducts. In contrast, repair-complemented UV-5 (expressing hamster XPD) and UV-41 (expressing human ERCC4) cells exhibited similar clonogenic survival and removed Cr-DNA adducts to a similar extent as AA8 cells. In order to extend these findings to the molecular level, we examined the ability of Cr(III)-damaged DNA to induce DNA repair synthesis in cell extracts. Repair synthesis was observed in reactions using extracts derived from AA8, or repair-complemented, but not NER-deficient cells. Cr(III)-induced repair resynthesis was sensitive to inhibition by the DNA polymerase delta/epsilon inhibitor, aphidicolin, but not 2',3'-dideoxythymidine triphosphate (ddTTP), a polymerase beta inhibitor. These results collectively suggest that NER functions in the protection of cells from Cr(VI) lethality and is essential for the removal of Cr(III)-DNA adducts. Consequently, NER may represent an important mechanism for preventing Cr(VI)-induced mutagenesis and neoplastic transformation.","Nucleotide excision repair functions in the removal of chromium-induced DNA damage in mammalian cells Abs: Some hexavalent chromium (Cr(VI))-containing compounds are human lung carcinogens. While ample information is available on the genetic lesions produced by Cr, surprisingly little is known regarding the cellular mechanisms involved in the removal of Cr-DNA adducts. Nucleotide excision repair (NER) is a highly versatile pathway that is responsive to a variety of DNA helix-distorting lesions. Binary Cr-DNA monoadducts do not produce a significant degree of helical distortion. However, these lesions are unstable due to the propensity of Cr(III) to form DNA adducts (DNA interstrand crosslinks, DNA-protein/amino acid ternary adducts) which may serve as substrates for NER. Therefore, the focus of this study was to determine the role of NER in the processing of Cr-DNA damage using normal (CHO-AA8) and NER-deficient [UV-5 (XP-D); UV-41 (ERCC4/XP-F)] hamster cells. We found that both UV-5 and UV-41 cells exhibited an increased sensitivity towards Cr(VI)-induced clonogenic lethality relative to AA8 cells and were completely deficient in the removal of Cr-DNA adducts. In contrast, repair-complemented UV-5 (expressing hamster XPD) and UV-41 (expressing human ERCC4) cells exhibited similar clonogenic survival and removed Cr-DNA adducts to a similar extent as AA8 cells. In order to extend these findings to the molecular level, we examined the ability of Cr(III)-damaged DNA to induce DNA repair synthesis in cell extracts. Repair synthesis was observed in reactions using extracts derived from AA8, or repair-complemented, but not NER-deficient cells. Cr(III)-induced repair resynthesis was sensitive to inhibition by the DNA polymerase delta/epsilon inhibitor, aphidicolin, but not 2',3'-dideoxythymidine triphosphate (ddTTP), a polymerase beta inhibitor. These results collectively suggest that NER functions in the protection of cells from Cr(VI) lethality and is essential for the removal of Cr(III)-DNA adducts. Consequently, NER may represent an important mechanism for preventing Cr(VI)-induced mutagenesis and neoplastic transformation."
1231853,Xie et al. 2006,Simultaneous photocatalytic reduction of Cr(VI) and oxidation of phenol over monoclinic BiVO4 under visible light irradiation,"BiVO4 powder with monoclinic structure was prepared and used as a visible-light catalyst simultaneously for the photooxidation of phenol and the photoreduction of Cr(VI). The photocatalytic efficiency was found to be rather low for either single phenol solution or single Cr(VI) solution. However, the photocatalytic reduction of Cr(VI) and photocatalytic oxidation of phenol proceed more rapidly for the coexistence system of phenol and Cr(VI) than for the single process, showing synergetic effect between the oxidation and reduction reactions. For the simultaneous photocatalytic reduction-oxidation process, the first-order kinetic constant of phenol degradation was 0.0314 min-1, being about six times higher than that for the photocatalytic process of single phenol. This result reveals the feasibility of using Cr(VI) as the electron scavenger of mBiVO4-mediated photocatalytic process of phenol degradation, and gives us an enlightenment to employ other semiconductor with a better visible light response but with a more positive band edge to efficiently degrade organic pollutants. This is the first report for simultaneous photocatalytic reduction of Cr(VI) and removal of phenol under visible light irradiation using photocatalyst mBiVO4.","Simultaneous photocatalytic reduction of Cr(VI) and oxidation of phenol over monoclinic BiVO4 under visible light irradiation Abs: BiVO4 powder with monoclinic structure was prepared and used as a visible-light catalyst simultaneously for the photooxidation of phenol and the photoreduction of Cr(VI). The photocatalytic efficiency was found to be rather low for either single phenol solution or single Cr(VI) solution. However, the photocatalytic reduction of Cr(VI) and photocatalytic oxidation of phenol proceed more rapidly for the coexistence system of phenol and Cr(VI) than for the single process, showing synergetic effect between the oxidation and reduction reactions. For the simultaneous photocatalytic reduction-oxidation process, the first-order kinetic constant of phenol degradation was 0.0314 min-1, being about six times higher than that for the photocatalytic process of single phenol. This result reveals the feasibility of using Cr(VI) as the electron scavenger of mBiVO4-mediated photocatalytic process of phenol degradation, and gives us an enlightenment to employ other semiconductor with a better visible light response but with a more positive band edge to efficiently degrade organic pollutants. This is the first report for simultaneous photocatalytic reduction of Cr(VI) and removal of phenol under visible light irradiation using photocatalyst mBiVO4."
1231851,Rodriguez and  Martinez 2005,Removal of Cr(VI) from wastewaters in a tubular electrochemical reactor,"This work aimed at studying the electrochemical reduction of the hexavalent chromium Cr(VI) by means of a tubular reactor operating under both continuous and batch regimes. It is shown that chromium (VI) reduction to chromium (III) was exerted not only by the oxidation of iron to Fe(II) released from the steel sacrifice anodes immersed in an acid solution to aid the overall process. Also, it is shown that there was an additional contribution to chromium reduction from an ancillary reaction at the cathode, where Fe(III) ions generated after the Cr(VI) reduction are again reduced to Fe(II), this being interpreted as a catalytic effect taking place. The results are presented at pH values of 1, 1.3, 1.7, and 2: it became clear that the variable affected the solubility of the species generated in solution. The initial chromium hexavalent concentration was 1000 mg L(- 1) and it was found that after treatment times ranging from 320 to 25 minutes this could reach values as low as 0.5 mg L(- 1), depending on the operating conditions.","Removal of Cr(VI) from wastewaters in a tubular electrochemical reactor Abs: This work aimed at studying the electrochemical reduction of the hexavalent chromium Cr(VI) by means of a tubular reactor operating under both continuous and batch regimes. It is shown that chromium (VI) reduction to chromium (III) was exerted not only by the oxidation of iron to Fe(II) released from the steel sacrifice anodes immersed in an acid solution to aid the overall process. Also, it is shown that there was an additional contribution to chromium reduction from an ancillary reaction at the cathode, where Fe(III) ions generated after the Cr(VI) reduction are again reduced to Fe(II), this being interpreted as a catalytic effect taking place. The results are presented at pH values of 1, 1.3, 1.7, and 2: it became clear that the variable affected the solubility of the species generated in solution. The initial chromium hexavalent concentration was 1000 mg L(- 1) and it was found that after treatment times ranging from 320 to 25 minutes this could reach values as low as 0.5 mg L(- 1), depending on the operating conditions."
1231850,Demoisson et al. 2005,Pyrite oxidation by hexavalent chromium: investigation of the chemical processes by monitoring of aqueous metal species,"Pyrite, an iron sulfide, occurs in many soils and sediments, making it an important natural reductant of toxic metal pollutants. This study investigated the processes leading to aqueous Cr(VI) reduction by pyrite in a closed thermostated (25 +/- 0.1 degrees C) system and under an argon atmosphere. Synthetic pyrite suspensions were reacted with a range of Cr(VI) solutions from 0 to 7 x 10(-4) M and at pH 2-8. Metal species concentrations were continuously monitored during a period lasting approximately 20 h. Preliminary experiments carried out in acidic media without Cr(VI) have shown that some pyrite dissolution occurred. Then, metal species concentration changes with time during pyrite oxidation by Cr(VI) solutions exhibited two distinct trends depending on the complete or incomplete Cr(VI) removal. As long as chromate existed in solution, the Cr-(Ill) to Fe(lIl) ratio was found to be an effective parameter to investigate the pyrite reaction stoichiometry with Cr(VI). Experimental values close to 2 suggest that sulfur compounds with oxidation states between 0 and 2 should be formed during pyrite oxidation by Cr(VI). If Cr(VI) was completely reduced from solution, then the pyrite oxidation by Fe(lll) ions took place to generate ferrous ions.","Pyrite oxidation by hexavalent chromium: investigation of the chemical processes by monitoring of aqueous metal species Abs: Pyrite, an iron sulfide, occurs in many soils and sediments, making it an important natural reductant of toxic metal pollutants. This study investigated the processes leading to aqueous Cr(VI) reduction by pyrite in a closed thermostated (25 +/- 0.1 degrees C) system and under an argon atmosphere. Synthetic pyrite suspensions were reacted with a range of Cr(VI) solutions from 0 to 7 x 10(-4) M and at pH 2-8. Metal species concentrations were continuously monitored during a period lasting approximately 20 h. Preliminary experiments carried out in acidic media without Cr(VI) have shown that some pyrite dissolution occurred. Then, metal species concentration changes with time during pyrite oxidation by Cr(VI) solutions exhibited two distinct trends depending on the complete or incomplete Cr(VI) removal. As long as chromate existed in solution, the Cr-(Ill) to Fe(lIl) ratio was found to be an effective parameter to investigate the pyrite reaction stoichiometry with Cr(VI). Experimental values close to 2 suggest that sulfur compounds with oxidation states between 0 and 2 should be formed during pyrite oxidation by Cr(VI). If Cr(VI) was completely reduced from solution, then the pyrite oxidation by Fe(lll) ions took place to generate ferrous ions."
1231849,Yang and  Lee 2006,Removal of Cr(VI) and humic acid by using TiO2 photocatalysis,"The removal efficiencies of Cr(VI) and HA, using a TiO(2)-mediated photocatalytic process, were investigated with variations in the pH, TiO(2) dosage and Cr(VI)/HA ratio. During the photocatalytic reaction, the total removal of Cr(VI) occurred through adsorption onto TiO(2), as well as its reduction to Cr(III). However, oxidation and adsorption were identified as important removal processes for the treatment of HA. Due to the anionic type adsorption onto TiO(2) and its acid-catalyzed photocatalytic reduction, the removal of Cr(VI) decreased with increasing pH, while that of HA increased with increasing pH. The TiO(2) dosage was also an important parameter for the removal of Cr(VI). As the TiO(2) dosage was increased to 2.5 g l(-1), the removal of Cr(VI) was continuously enhanced, but decreased at dosages above 3 g l(-1) due to the increased blockage of the incident UV light used for the photocatalytic reaction. The removal of Cr(VI) was greatly enhanced when the system contained both HA and Cr(VI) compared to Cr(VI) alone. Also, the removal of HA was greatly enhanced when the system contained both HA and Cr(VI) compared to HA alone. The removal of Cr(VI) was continuously enhanced as the HA concentration gradually increased; however, no further increase was observed above 20 mg l(-1) HA due to the increased absorption of the UV light. This result supports that the photocatalytic reaction, with illuminated TiO(2), could be applied to more effectively treat wastewater containing both Cr(VI) and HA than that containing a single species only.","Removal of Cr(VI) and humic acid by using TiO2 photocatalysis Abs: The removal efficiencies of Cr(VI) and HA, using a TiO(2)-mediated photocatalytic process, were investigated with variations in the pH, TiO(2) dosage and Cr(VI)/HA ratio. During the photocatalytic reaction, the total removal of Cr(VI) occurred through adsorption onto TiO(2), as well as its reduction to Cr(III). However, oxidation and adsorption were identified as important removal processes for the treatment of HA. Due to the anionic type adsorption onto TiO(2) and its acid-catalyzed photocatalytic reduction, the removal of Cr(VI) decreased with increasing pH, while that of HA increased with increasing pH. The TiO(2) dosage was also an important parameter for the removal of Cr(VI). As the TiO(2) dosage was increased to 2.5 g l(-1), the removal of Cr(VI) was continuously enhanced, but decreased at dosages above 3 g l(-1) due to the increased blockage of the incident UV light used for the photocatalytic reaction. The removal of Cr(VI) was greatly enhanced when the system contained both HA and Cr(VI) compared to Cr(VI) alone. Also, the removal of HA was greatly enhanced when the system contained both HA and Cr(VI) compared to HA alone. The removal of Cr(VI) was continuously enhanced as the HA concentration gradually increased; however, no further increase was observed above 20 mg l(-1) HA due to the increased absorption of the UV light. This result supports that the photocatalytic reaction, with illuminated TiO(2), could be applied to more effectively treat wastewater containing both Cr(VI) and HA than that containing a single species only."
1231848,Park et al. 2006,Comment on &quot;sorption of Cr(VI) from dilute solutions and wastewater by live and pretreated biomass of Aspergillus flavus&quot; by Deepa et al,,Comment on &quot;sorption of Cr(VI) from dilute solutions and wastewater by live and pretreated biomass of Aspergillus flavus&quot; by Deepa et al Abs: 
1231847,Levina et al. 2006,Binding of chromium(VI) to histones: implications for chromium(VI)-induced genotoxicity,"The first evidence has been obtained for Cr(VI) (chromate) binding to isolated calf thymus (CT) histones under physiological conditions (pH 7.4, Cl(-) concentration 152 mM, 310 K). No significant Cr(VI) binding under the same conditions was observed for other extracellular and intracellular proteins, including albumin, apo-transferrin and G-actin, as well as for CT DNA. The mode of Cr(VI) binding to histones was studied by vibrational, electronic and X-ray absorption (X-ray absorption near-edge structure and X-ray absorption fine structure) spectroscopies and molecular mechanics calculations. A proposed binding mechanism includes electrostatic interactions of CrO(4) (2-) with protonated Lys and Arg residues of histones, as well as the formation of hydrogen bonds with the protein backbone. Similarly, Cr(VI) can bind to nuclear localization signals (typically, Lys- and Arg-rich fragments) of other nuclear proteins. Selective binding of Cr(VI) to newly synthesized nuclear proteins (including histones) in the cytoplasm is likely to be responsible for the active transport of Cr(VI) into the nuclei of living cells.","Binding of chromium(VI) to histones: implications for chromium(VI)-induced genotoxicity Abs: The first evidence has been obtained for Cr(VI) (chromate) binding to isolated calf thymus (CT) histones under physiological conditions (pH 7.4, Cl(-) concentration 152 mM, 310 K). No significant Cr(VI) binding under the same conditions was observed for other extracellular and intracellular proteins, including albumin, apo-transferrin and G-actin, as well as for CT DNA. The mode of Cr(VI) binding to histones was studied by vibrational, electronic and X-ray absorption (X-ray absorption near-edge structure and X-ray absorption fine structure) spectroscopies and molecular mechanics calculations. A proposed binding mechanism includes electrostatic interactions of CrO(4) (2-) with protonated Lys and Arg residues of histones, as well as the formation of hydrogen bonds with the protein backbone. Similarly, Cr(VI) can bind to nuclear localization signals (typically, Lys- and Arg-rich fragments) of other nuclear proteins. Selective binding of Cr(VI) to newly synthesized nuclear proteins (including histones) in the cytoplasm is likely to be responsible for the active transport of Cr(VI) into the nuclei of living cells."
1231846,Gheju and  Iovi 2006,Kinetics of hexavalent chromium reduction by scrap iron,"The kinetics of Cr(VI) reduction by scrap iron was investigated in batch system, for aqueous solutions having low buffering capacities, as a function of pH (2.10-7.10), temperature (10-40 degrees C) and Cr(VI) concentration (19.2-576.9 microM). The results obtained using only the experimental data at initial times indicate zero-order kinetics at pH 2.10 and first-order kinetics over the pH range of 2.98-7.10. The reaction order with respect to H(+) concentration, over the pH range of 4.17-7.10 and Cr(VI) concentration range of 19.2-38.4 microM, was found to be 0.31. The effects of pH, Cr(VI) initial concentration and temperature were investigated; the observed Cr(VI) reduction rates increased with decreasing pH, increasing temperature and decreasing initial Cr(VI) concentration. The observed and overall rate coefficients were determined, and a kinetic expression was developed to describe reduction of chromium by scrap iron over the pH range of 4.17-7.10 and Cr(VI) concentration range of 19.2-38.4 microM.","Kinetics of hexavalent chromium reduction by scrap iron Abs: The kinetics of Cr(VI) reduction by scrap iron was investigated in batch system, for aqueous solutions having low buffering capacities, as a function of pH (2.10-7.10), temperature (10-40 degrees C) and Cr(VI) concentration (19.2-576.9 microM). The results obtained using only the experimental data at initial times indicate zero-order kinetics at pH 2.10 and first-order kinetics over the pH range of 2.98-7.10. The reaction order with respect to H(+) concentration, over the pH range of 4.17-7.10 and Cr(VI) concentration range of 19.2-38.4 microM, was found to be 0.31. The effects of pH, Cr(VI) initial concentration and temperature were investigated; the observed Cr(VI) reduction rates increased with decreasing pH, increasing temperature and decreasing initial Cr(VI) concentration. The observed and overall rate coefficients were determined, and a kinetic expression was developed to describe reduction of chromium by scrap iron over the pH range of 4.17-7.10 and Cr(VI) concentration range of 19.2-38.4 microM."
1231845,Lo et al. 2006,Hardness and carbonate effects on the reactivity of zero-valent iron for Cr(VI) removal,"Zero-valent iron (Fe0) was used to remove hexavalent chromium, Cr(VI), in groundwater via a coupled reduction-oxidation reaction. Nine columns were set up under various groundwater geochemistry to investigate the effects of hardness and carbonate on Cr(VI) removal. The Cr(VI) removal capacity of Fe0 was found to be about 4 mgCr/g Fe0 in the control column (i.e., column 1). A slight decrease in the Cr(VI) removal capacity was found in the presence of calcium hardness. However, there was a 17% drop in the Cr(VI) removal capacity when magnesium hardness was present at low to moderately hard level. Results also revealed that carbonate changed the morphology of the Fe0 by formation of pale green precipitates on the iron filings. Furthermore, there was a 33% decrease in the Cr(VI) removal capacity of Fe0 when both carbonate and hardness ions were present. In general, the presence of hardness ions and carbonate in groundwater have great impact on the Fe0 by formation of passivated precipitates, such as CaCO3, on the Fe0 surface resulting in a diminished lifespan of the Fe0 by blocking electron transfer.","Hardness and carbonate effects on the reactivity of zero-valent iron for Cr(VI) removal Abs: Zero-valent iron (Fe0) was used to remove hexavalent chromium, Cr(VI), in groundwater via a coupled reduction-oxidation reaction. Nine columns were set up under various groundwater geochemistry to investigate the effects of hardness and carbonate on Cr(VI) removal. The Cr(VI) removal capacity of Fe0 was found to be about 4 mgCr/g Fe0 in the control column (i.e., column 1). A slight decrease in the Cr(VI) removal capacity was found in the presence of calcium hardness. However, there was a 17% drop in the Cr(VI) removal capacity when magnesium hardness was present at low to moderately hard level. Results also revealed that carbonate changed the morphology of the Fe0 by formation of pale green precipitates on the iron filings. Furthermore, there was a 33% decrease in the Cr(VI) removal capacity of Fe0 when both carbonate and hardness ions were present. In general, the presence of hardness ions and carbonate in groundwater have great impact on the Fe0 by formation of passivated precipitates, such as CaCO3, on the Fe0 surface resulting in a diminished lifespan of the Fe0 by blocking electron transfer."
1231844,Paul and  Jacobs 2005,Spectrophotometric detection of iodide and chromic (III) in urine after oxidation to iodine and chromate (VI),"Tests for oxidizing adulterants in urine are a continuing challenge to the drug-testing program. Iodine was found to destroy morphine and 6-acetylmorphine almost immediately. The effects were less evident on 11 -nor-delta9-tetrahydrocannabinol-9-carboxylic acid (THC-acid). When the urine solution was tested for iodine by a chromogenic substrate, 2,2'-azino-bis(3-ethylbenzthiazoline-6-sulfonic acid) (ABTS), no iodine was detected. Masking drug and adulterant simultaneously made iodine a preferred oxidizing adulterant for drug abusers. In this study, the reduced iodide was oxidized by sodium nitrite to iodine. The excess nitrite was decomposed by sulfamic acid and the iodine was detected by ABTS. Linearity was 12.7 to 635 mg/L (0.1 to 5 mmol/L, y = 0.9966x + 0.0016, R2 = 1.0000). Precisions (coefficient of variation) were within +/- 4.1% and quantitative accuracies were within 97% of expected values (n=5). Chromate, iodate, periodate, and persulfate interfered with the method. To alleviate the problem, the positive specimens were tested again by an iodine-specific method. After oxidation, the samples were treated with sodium azide and ammonium thiocyanate. In presence of thiocyanate, the azide reduced iodine to iodide almost immediately, and the solutions showed negative response to ABTS. The results were compared with that of a control group tested without thiocyanate. When iodine was present, the ratios of thiocyanate to control were less than 6%. Chromate was also found to destroy THC-acid in urine, and during storage most of the chromate changed to chromic (III). In this study, chromic was oxidized to chromate by hydrogen peroxide and sodium hydroxide and detected by 1,5-diphenylcarbazide. Linearity was 5.2 to 156 mg/L (0.1 to 3.0 mmol/L, y = 1.0285x - 0.0034, R2 = 0.9998). Precisions were within +/- 8.5% and quantitative accuracies were within 92% of expected values (n=5). The test was not interfered by other oxidizing agents. Both iodide and chromic oxidation methods showed urine backgrounds less than 1.27 and 0.52 mg/L, respectively (&lt; 0.01 mmol/L). It indicated that a response more than 10 times of the background could be considered as oxidant contamination or adulteration of urine specimens.","Spectrophotometric detection of iodide and chromic (III) in urine after oxidation to iodine and chromate (VI) Abs: Tests for oxidizing adulterants in urine are a continuing challenge to the drug-testing program. Iodine was found to destroy morphine and 6-acetylmorphine almost immediately. The effects were less evident on 11 -nor-delta9-tetrahydrocannabinol-9-carboxylic acid (THC-acid). When the urine solution was tested for iodine by a chromogenic substrate, 2,2'-azino-bis(3-ethylbenzthiazoline-6-sulfonic acid) (ABTS), no iodine was detected. Masking drug and adulterant simultaneously made iodine a preferred oxidizing adulterant for drug abusers. In this study, the reduced iodide was oxidized by sodium nitrite to iodine. The excess nitrite was decomposed by sulfamic acid and the iodine was detected by ABTS. Linearity was 12.7 to 635 mg/L (0.1 to 5 mmol/L, y = 0.9966x + 0.0016, R2 = 1.0000). Precisions (coefficient of variation) were within +/- 4.1% and quantitative accuracies were within 97% of expected values (n=5). Chromate, iodate, periodate, and persulfate interfered with the method. To alleviate the problem, the positive specimens were tested again by an iodine-specific method. After oxidation, the samples were treated with sodium azide and ammonium thiocyanate. In presence of thiocyanate, the azide reduced iodine to iodide almost immediately, and the solutions showed negative response to ABTS. The results were compared with that of a control group tested without thiocyanate. When iodine was present, the ratios of thiocyanate to control were less than 6%. Chromate was also found to destroy THC-acid in urine, and during storage most of the chromate changed to chromic (III). In this study, chromic was oxidized to chromate by hydrogen peroxide and sodium hydroxide and detected by 1,5-diphenylcarbazide. Linearity was 5.2 to 156 mg/L (0.1 to 3.0 mmol/L, y = 1.0285x - 0.0034, R2 = 0.9998). Precisions were within +/- 8.5% and quantitative accuracies were within 92% of expected values (n=5). The test was not interfered by other oxidizing agents. Both iodide and chromic oxidation methods showed urine backgrounds less than 1.27 and 0.52 mg/L, respectively (&lt; 0.01 mmol/L). It indicated that a response more than 10 times of the background could be considered as oxidant contamination or adulteration of urine specimens."
1231842,Horton et al. 2006,Low temperature reduction of hexavalent chromium by a microbial enrichment consortium and a novel strain of Arthrobacter aurescens,"<strong>BACKGROUND: </strong>Chromium is a transition metal most commonly found in the environment in its trivalent [Cr(III)] and hexavalent [Cr(VI)] forms. The EPA maximum total chromium contaminant level for drinking water is 0.1 mg/l (0.1 ppm). Many water sources, especially underground sources, are at low temperatures (less than or equal to 15 Centigrade) year round. It is important to evaluate the possibility of microbial remediation of Cr(VI) contamination using microorganisms adapted to these low temperatures (psychrophiles).<br /><br /><strong>RESULTS: </strong>Core samples obtained from a Cr(VI) contaminated aquifer at the Hanford facility in Washington were enriched in Vogel Bonner medium at 10 Centigrade with 0, 25, 50, 100, 200, 400 and 1000 mg/l Cr(VI). The extent of Cr(VI) reduction was evaluated using the diphenyl carbazide assay. Resistance to Cr(VI) up to and including 1000 mg/l Cr(VI) was observed in the consortium experiments. Reduction was slow or not observed at and above 100 mg/l Cr(VI) using the enrichment consortium. Average time to complete reduction of Cr(VI) in the 30 and 60 mg/l Cr(VI) cultures of the consortium was 8 and 17 days, respectively at 10 Centigrade. Lyophilized consortium cells did not demonstrate adsorption of Cr(VI) over a 24 hour period. Successful isolation of a Cr(VI) reducing organism (designated P4) from the consortium was confirmed by 16S rDNA amplification and sequencing. Average time to complete reduction of Cr(VI) at 10 Centigrade in the 25 and 50 mg/l Cr(VI) cultures of the isolate P4 was 3 and 5 days, respectively. The 16S rDNA sequence from isolate P4 identified this organism as a strain of Arthrobacter aurescens, a species that has not previously been shown to be capable of low temperature Cr(VI) reduction.<br /><br /><strong>CONCLUSION: </strong>A. aurescens, indigenous to the subsurface, has the potential to be a predominant metal reducer in enhanced, in situ subsurface bioremediation efforts involving Cr(VI) and possibly other heavy metals and radionuclides.","Low temperature reduction of hexavalent chromium by a microbial enrichment consortium and a novel strain of Arthrobacter aurescens Abs: <strong>BACKGROUND: </strong>Chromium is a transition metal most commonly found in the environment in its trivalent [Cr(III)] and hexavalent [Cr(VI)] forms. The EPA maximum total chromium contaminant level for drinking water is 0.1 mg/l (0.1 ppm). Many water sources, especially underground sources, are at low temperatures (less than or equal to 15 Centigrade) year round. It is important to evaluate the possibility of microbial remediation of Cr(VI) contamination using microorganisms adapted to these low temperatures (psychrophiles).<br /><br /><strong>RESULTS: </strong>Core samples obtained from a Cr(VI) contaminated aquifer at the Hanford facility in Washington were enriched in Vogel Bonner medium at 10 Centigrade with 0, 25, 50, 100, 200, 400 and 1000 mg/l Cr(VI). The extent of Cr(VI) reduction was evaluated using the diphenyl carbazide assay. Resistance to Cr(VI) up to and including 1000 mg/l Cr(VI) was observed in the consortium experiments. Reduction was slow or not observed at and above 100 mg/l Cr(VI) using the enrichment consortium. Average time to complete reduction of Cr(VI) in the 30 and 60 mg/l Cr(VI) cultures of the consortium was 8 and 17 days, respectively at 10 Centigrade. Lyophilized consortium cells did not demonstrate adsorption of Cr(VI) over a 24 hour period. Successful isolation of a Cr(VI) reducing organism (designated P4) from the consortium was confirmed by 16S rDNA amplification and sequencing. Average time to complete reduction of Cr(VI) at 10 Centigrade in the 25 and 50 mg/l Cr(VI) cultures of the isolate P4 was 3 and 5 days, respectively. The 16S rDNA sequence from isolate P4 identified this organism as a strain of Arthrobacter aurescens, a species that has not previously been shown to be capable of low temperature Cr(VI) reduction.<br /><br /><strong>CONCLUSION: </strong>A. aurescens, indigenous to the subsurface, has the potential to be a predominant metal reducer in enhanced, in situ subsurface bioremediation efforts involving Cr(VI) and possibly other heavy metals and radionuclides."
1231841,Graham et al. 2006,Calcium polysulfide remediation of hexavalent chromium contamination from chromite ore processing residue,"Past disposal of high-lime chromite ore processing residue (COPR) from a chemical works in S.E. Glasgow, UK, has led to continuing release of toxic and carcinogenic hexavalent chromium (Cr(VI)) to groundwaters which are highly contaminated with Cr(VI)O4(2-). Traditional methods of remediating Cr(VI)-contaminated land, e.g. using ferrous sulfate and organic matter, have had limited success in converting Cr(VI) to less harmful and insoluble Cr(III). This paper describes the first application of calcium polysulfide (CaS(x)) to the remediation of contaminated groundwater and high-lime COPR in a series of laboratory experiments, which have demonstrated the effectiveness of the treatment in quantitatively and rapidly reducing Cr(VI) to Cr(III) over the pH range (8-12.5) typically found at the sites. Cr(III)-organic complexes, present in groundwater at one location, were also effectively precipitated upon treatment with CaS(x). The potential for large-scale use of CaS(x) in the remediation of Cr(VI) from COPR is also discussed.","Calcium polysulfide remediation of hexavalent chromium contamination from chromite ore processing residue Abs: Past disposal of high-lime chromite ore processing residue (COPR) from a chemical works in S.E. Glasgow, UK, has led to continuing release of toxic and carcinogenic hexavalent chromium (Cr(VI)) to groundwaters which are highly contaminated with Cr(VI)O4(2-). Traditional methods of remediating Cr(VI)-contaminated land, e.g. using ferrous sulfate and organic matter, have had limited success in converting Cr(VI) to less harmful and insoluble Cr(III). This paper describes the first application of calcium polysulfide (CaS(x)) to the remediation of contaminated groundwater and high-lime COPR in a series of laboratory experiments, which have demonstrated the effectiveness of the treatment in quantitatively and rapidly reducing Cr(VI) to Cr(III) over the pH range (8-12.5) typically found at the sites. Cr(III)-organic complexes, present in groundwater at one location, were also effectively precipitated upon treatment with CaS(x). The potential for large-scale use of CaS(x) in the remediation of Cr(VI) from COPR is also discussed."
1231840,Steiner et al. 2006,Ultrafast concentration and speciation of chromium(III) and (VI),"There is an increasing need to know the concentrations of chromium(III) and (VI) separately rather than only the total chromium content. A method is described for accomplishing this very quickly using only low-cost, portable equipment. Two small, resin-loaded extraction disks are placed one on top of the other in a plastic holder. Then a syringe containing the aqueous sample is attached to the holder and the sample is pushed through the disks. In a matter of seconds, all of the chromium(VI) is retained on the top anion-exchange disk and chromium(III) is extracted by the second cation-exchange disk. The concentrations on each disk are several hundredfold higher than they were in the original sample. The amounts of chromium(III) and (VI) extracted are measured directly on the surface of the respective disks by diffuse reflectance spectroscopy (DRS). Despite the low molar absorptivity of chromium(III) in aqueous solution, the concentration on the upper most layer on the extraction disk is high enough to permit the determination of chromium(III) in samples at the low mg/L range. Chromium(VI) can also be determined at low to sub-mg/L concentrations. A study of the cation-exchange disks was undertaken to compare the performance characteristics of disks containing sulfonated resins and those with iminodiacetate functionality. In addition, data are presented to show the effects of heating the iminodiacetate disks after the initial extraction. The disks were heated in hot water for 15-30 min to complete the slow complexation reaction on the surface.","Ultrafast concentration and speciation of chromium(III) and (VI) Abs: There is an increasing need to know the concentrations of chromium(III) and (VI) separately rather than only the total chromium content. A method is described for accomplishing this very quickly using only low-cost, portable equipment. Two small, resin-loaded extraction disks are placed one on top of the other in a plastic holder. Then a syringe containing the aqueous sample is attached to the holder and the sample is pushed through the disks. In a matter of seconds, all of the chromium(VI) is retained on the top anion-exchange disk and chromium(III) is extracted by the second cation-exchange disk. The concentrations on each disk are several hundredfold higher than they were in the original sample. The amounts of chromium(III) and (VI) extracted are measured directly on the surface of the respective disks by diffuse reflectance spectroscopy (DRS). Despite the low molar absorptivity of chromium(III) in aqueous solution, the concentration on the upper most layer on the extraction disk is high enough to permit the determination of chromium(III) in samples at the low mg/L range. Chromium(VI) can also be determined at low to sub-mg/L concentrations. A study of the cation-exchange disks was undertaken to compare the performance characteristics of disks containing sulfonated resins and those with iminodiacetate functionality. In addition, data are presented to show the effects of heating the iminodiacetate disks after the initial extraction. The disks were heated in hot water for 15-30 min to complete the slow complexation reaction on the surface."
1231839,Hook et al. 2006,"Gene expression patterns in rainbow trout, Oncorhynchus mykiss, exposed to a suite of model toxicants","The increased availability and use of DNA microarrays has allowed the characterization of gene expression patterns associated with exposure to different toxicants. An important question is whether toxicant induced changes in gene expression in fish are sufficiently diverse to allow for identification of specific modes of action and/or specific contaminants. In theory, each class of toxicant may generate a gene expression profile unique to its mode of toxic action. In this study, isogenic (cloned) rainbow trout Oncorhynchus mykiss were exposed to sublethal levels of a series of model toxicants with varying modes of action, including ethynylestradiol (xeno-estrogen), 2,2,4,4'-tetrabromodiphenyl ether (BDE-47, thyroid active), diquat (oxidant stressor), chromium VI, and benzo[a]pyrene (BaP) for a period of 1-3 weeks. An additional experiment measured trenbolone (anabolic steroid; model androgen) induced gene expression changes in sexually mature female trout. Following exposure, fish were euthanized, livers removed and RNA extracted. Fluorescently labeled cDNA were generated and hybridized against a commercially available Atlantic Salmon/Trout array (GRASP project, University of Victoria) spotted with 16,000 cDNA's. The slides were scanned to measure abundance of a given transcript in each sample relative to controls. Data were analyzed via Genespring (Silicon Genetics) to identify a list of up- and downregulated genes, as well as to determine gene clustering patterns that can be used as &quot;expression signatures&quot;. The results indicate each toxicant exposure caused between 64 and 222 genes to be significantly altered in expression. Most genes exhibiting altered expression responded to only one of the toxicants and relatively few were co-expressed in multiple treatments. For example, BaP and Diquat, both of which exert toxicity via oxidative stress, upregulated 28 of the same genes, of over 100 genes altered by either treatment. Other genes associated with steroidogenesis, p450 and estrogen responsive genes appear to be useful for selectively identifying toxicant mode of action in fish, suggesting a link between gene expression profile and mode of toxicity. Our array results showed good agreement with quantitative real time polymerase chain reaction (qRT PCR), which demonstrates that the arrays are an accurate measure of gene expression. The specificity of the gene expression profile in response to a model toxicant, the link between genes with altered expression and mode of toxic action, and the consistency between array and qRT PCR results all suggest that cDNA microarrays have the potential to screen environmental contaminants for biomarkers and mode of toxic action.","Gene expression patterns in rainbow trout, Oncorhynchus mykiss, exposed to a suite of model toxicants Abs: The increased availability and use of DNA microarrays has allowed the characterization of gene expression patterns associated with exposure to different toxicants. An important question is whether toxicant induced changes in gene expression in fish are sufficiently diverse to allow for identification of specific modes of action and/or specific contaminants. In theory, each class of toxicant may generate a gene expression profile unique to its mode of toxic action. In this study, isogenic (cloned) rainbow trout Oncorhynchus mykiss were exposed to sublethal levels of a series of model toxicants with varying modes of action, including ethynylestradiol (xeno-estrogen), 2,2,4,4'-tetrabromodiphenyl ether (BDE-47, thyroid active), diquat (oxidant stressor), chromium VI, and benzo[a]pyrene (BaP) for a period of 1-3 weeks. An additional experiment measured trenbolone (anabolic steroid; model androgen) induced gene expression changes in sexually mature female trout. Following exposure, fish were euthanized, livers removed and RNA extracted. Fluorescently labeled cDNA were generated and hybridized against a commercially available Atlantic Salmon/Trout array (GRASP project, University of Victoria) spotted with 16,000 cDNA's. The slides were scanned to measure abundance of a given transcript in each sample relative to controls. Data were analyzed via Genespring (Silicon Genetics) to identify a list of up- and downregulated genes, as well as to determine gene clustering patterns that can be used as &quot;expression signatures&quot;. The results indicate each toxicant exposure caused between 64 and 222 genes to be significantly altered in expression. Most genes exhibiting altered expression responded to only one of the toxicants and relatively few were co-expressed in multiple treatments. For example, BaP and Diquat, both of which exert toxicity via oxidative stress, upregulated 28 of the same genes, of over 100 genes altered by either treatment. Other genes associated with steroidogenesis, p450 and estrogen responsive genes appear to be useful for selectively identifying toxicant mode of action in fish, suggesting a link between gene expression profile and mode of toxicity. Our array results showed good agreement with quantitative real time polymerase chain reaction (qRT PCR), which demonstrates that the arrays are an accurate measure of gene expression. The specificity of the gene expression profile in response to a model toxicant, the link between genes with altered expression and mode of toxic action, and the consistency between array and qRT PCR results all suggest that cDNA microarrays have the potential to screen environmental contaminants for biomarkers and mode of toxic action."
1231838,Sultan and  Hasnain 2007,Reduction of toxic hexavalent chromium by Ochrobactrum intermedium strain SDCr-5 stimulated by heavy metals,"A Cr(VI) resistant bacterial strain SDCr-5, identified as Ochrobactrum intermedium on the basis of 16S rRNA gene sequencing, was tolerant to high concentrations of Cr(VI) up to 15 mg ml(-1) in acetate minimal medium. O. intermedium SDCr-5 reduced Cr(VI) under a wide range of concentrations from 100 to 1500 microg ml(-1) and reduction was optimum at 37 degrees C and pH 7. It reduced 200 and 721 microg ml(-1) Cr(VI) within 72 and 96 h, respectively. The rate of Cr(VI) reduction increased with concentration from 100 to 1500 microg ml(-1). The presence of heavy metal cations such as Cu(2+), Co(2+), Mn(2+) and Ni(2+) stimulated Cr(VI) reduction. Strain SDCr-5 might be useful for Cr(VI) detoxification under a wide range of environmental conditions.","Reduction of toxic hexavalent chromium by Ochrobactrum intermedium strain SDCr-5 stimulated by heavy metals Abs: A Cr(VI) resistant bacterial strain SDCr-5, identified as Ochrobactrum intermedium on the basis of 16S rRNA gene sequencing, was tolerant to high concentrations of Cr(VI) up to 15 mg ml(-1) in acetate minimal medium. O. intermedium SDCr-5 reduced Cr(VI) under a wide range of concentrations from 100 to 1500 microg ml(-1) and reduction was optimum at 37 degrees C and pH 7. It reduced 200 and 721 microg ml(-1) Cr(VI) within 72 and 96 h, respectively. The rate of Cr(VI) reduction increased with concentration from 100 to 1500 microg ml(-1). The presence of heavy metal cations such as Cu(2+), Co(2+), Mn(2+) and Ni(2+) stimulated Cr(VI) reduction. Strain SDCr-5 might be useful for Cr(VI) detoxification under a wide range of environmental conditions."
1231837,Park and  Stayner 2006,A search for thresholds and other nonlinearities in the relationship between hexavalent chromium and lung cancer,"The exposure-response relationship for airborne hexavalent chromium exposure and lung cancer mortality is well described by a linear relative rate model. However, categorical analyses have been interpreted to suggest the presence of a threshold. This study investigates nonlinear features of the exposure response in a cohort of 2,357 chemical workers with 122 lung cancer deaths. In Poisson regression, a simple model representing a two-step carcinogenesis process was evaluated. In a one-stage context, fractional polynomials were investigated. Cumulative exposure dose metrics were examined corresponding to cumulative exposure thresholds, exposure intensity (concentration) thresholds, dose-rate effects, and declining burden of accumulated effect on future risk. A simple two-stage model of carcinogenesis provided no improvement in fit. The best-fitting one-stage models used simple cumulative exposure with no threshold for exposure intensity and had sufficient power to rule out thresholds as large as 30 microg/m3 CrO3 (16 microg/m3 as Cr+6) (one-sided 95% confidence limit, likelihood ratio test). Slightly better-fitting models were observed with cumulative exposure thresholds of 0.03 and 0.5 mg-yr/m3 (as CrO3) with and without an exposure-race interaction term, respectively. With the best model, cumulative exposure thresholds as large as 0.4 mg-yr/m3 CrO3 were excluded (two-sided upper 95% confidence limit, likelihood ratio test). A small departure from dose-rate linearity was observed, corresponding to (intensity)0.8 but was not statistically significant. Models in which risk-inducing damage burdens declined over time, based on half-lives ranging from 0.1 to 40 years, fit less well than assuming a constant burden. A half-life of 8 years or less was excluded (one-sided 95% confidence limit). Examination of nonlinear features of the hexavalent chromium-lung cancer exposure response in a population used in a recent risk assessment supports using the traditional (lagged) cumulative exposure paradigm: no intensity (concentration) threshold, linearity in intensity, and constant increment in risk following exposure.","A search for thresholds and other nonlinearities in the relationship between hexavalent chromium and lung cancer Abs: The exposure-response relationship for airborne hexavalent chromium exposure and lung cancer mortality is well described by a linear relative rate model. However, categorical analyses have been interpreted to suggest the presence of a threshold. This study investigates nonlinear features of the exposure response in a cohort of 2,357 chemical workers with 122 lung cancer deaths. In Poisson regression, a simple model representing a two-step carcinogenesis process was evaluated. In a one-stage context, fractional polynomials were investigated. Cumulative exposure dose metrics were examined corresponding to cumulative exposure thresholds, exposure intensity (concentration) thresholds, dose-rate effects, and declining burden of accumulated effect on future risk. A simple two-stage model of carcinogenesis provided no improvement in fit. The best-fitting one-stage models used simple cumulative exposure with no threshold for exposure intensity and had sufficient power to rule out thresholds as large as 30 microg/m3 CrO3 (16 microg/m3 as Cr+6) (one-sided 95% confidence limit, likelihood ratio test). Slightly better-fitting models were observed with cumulative exposure thresholds of 0.03 and 0.5 mg-yr/m3 (as CrO3) with and without an exposure-race interaction term, respectively. With the best model, cumulative exposure thresholds as large as 0.4 mg-yr/m3 CrO3 were excluded (two-sided upper 95% confidence limit, likelihood ratio test). A small departure from dose-rate linearity was observed, corresponding to (intensity)0.8 but was not statistically significant. Models in which risk-inducing damage burdens declined over time, based on half-lives ranging from 0.1 to 40 years, fit less well than assuming a constant burden. A half-life of 8 years or less was excluded (one-sided 95% confidence limit). Examination of nonlinear features of the hexavalent chromium-lung cancer exposure response in a population used in a recent risk assessment supports using the traditional (lagged) cumulative exposure paradigm: no intensity (concentration) threshold, linearity in intensity, and constant increment in risk following exposure."
1231836,Montes-Holguin et al. 2006,Biochemical and spectroscopic studies of the response of Convolvulus arvensis L. to chromium(III) and chromium(VI) stress,"The objective of the present study was to determine the oxidative stress caused by hexavalent chromium (Cr[VI]), the chromium (Cr) uptake, and the Cr speciation in Convolvulus arvensis L. plants grown in hydroponics media containing either Cr(VI) or Cr(III). The results demonstrated that C. arvensis plants exposed to Cr(VI) concentrations ranging from 0 to 40 mg/L expressed higher ascorbate peroxidase specific activity in roots than in shoots. On the other hand, catalase activity monitored in plants exposed to 2 mg/L of Cr(VI) for 24 h increased in roots after a few hours of exposure. However, catalase activity in shoots revealed a decrement almost immediately after treatment was initiated. The results from x-ray absorption spectroscopic studies indicated that the oxidation state of the supplied Cr(III) remained the same in plant tissues. The supplied Cr(VI), however, was reduced to the trivalent form in plant tissues. The results of inductively coupled plasma/optical emission spectroscopy demonstrated that after 5 d, the roots of plants exposed to 40 mg/L of Cr(III) or Cr(VI) accumulated approximately 25,000 and 3,500 mg/kg dry weight of Cr, respectively. Nevertheless, shoots concentrated 1,500 and 2,000 mg/kg dry weight of Cr from Cr(III) and Cr(VI), respectively, which indicated that Cr moved faster into C. arvensis plants when supplied as Cr(VI).","Biochemical and spectroscopic studies of the response of Convolvulus arvensis L. to chromium(III) and chromium(VI) stress Abs: The objective of the present study was to determine the oxidative stress caused by hexavalent chromium (Cr[VI]), the chromium (Cr) uptake, and the Cr speciation in Convolvulus arvensis L. plants grown in hydroponics media containing either Cr(VI) or Cr(III). The results demonstrated that C. arvensis plants exposed to Cr(VI) concentrations ranging from 0 to 40 mg/L expressed higher ascorbate peroxidase specific activity in roots than in shoots. On the other hand, catalase activity monitored in plants exposed to 2 mg/L of Cr(VI) for 24 h increased in roots after a few hours of exposure. However, catalase activity in shoots revealed a decrement almost immediately after treatment was initiated. The results from x-ray absorption spectroscopic studies indicated that the oxidation state of the supplied Cr(III) remained the same in plant tissues. The supplied Cr(VI), however, was reduced to the trivalent form in plant tissues. The results of inductively coupled plasma/optical emission spectroscopy demonstrated that after 5 d, the roots of plants exposed to 40 mg/L of Cr(III) or Cr(VI) accumulated approximately 25,000 and 3,500 mg/kg dry weight of Cr, respectively. Nevertheless, shoots concentrated 1,500 and 2,000 mg/kg dry weight of Cr from Cr(III) and Cr(VI), respectively, which indicated that Cr moved faster into C. arvensis plants when supplied as Cr(VI)."
1231835,Goldbohm et al. 2006,"Risk estimation for carcinogens based on epidemiological data: a structured approach, illustrated by an example on chromium","It is generally recognized that human, epidemiological data, if available, are preferred as the starting point for quantitative risk analysis above the use of data from animal studies. Although methods to obtain proper risk estimates from epidemiological data are available, several impediments prevent their widespread application. These impediments include unfamiliarity with epidemiological methods and the lack of a structured and transparent approach. We described a framework to conduct quantitative cancer risk assessment based on epidemiological studies in a structured, transparent, and reproducible manner. Important features of the process include a weight-of-the-evidence approach, estimation of the optimal exposure-risk function by fitting a regression model to the epidemiological data, estimation of uncertainty introduced by potential biases and missing information in the epidemiological studies, and calculation of excess lifetime risk through a life table to take into account competing risks. Sensitivity analyses are a useful tool to obtain insight into the impact of assumptions made and the variability of the underlying data. The framework is sufficiently flexible to allow many types of data, ranging from published, sometimes incomplete data to detailed individual data, while maintaining an optimal result, i.e., a state-of-the-art risk estimate with confidence intervals, based on all available evidence of sufficient quality.","Risk estimation for carcinogens based on epidemiological data: a structured approach, illustrated by an example on chromium Abs: It is generally recognized that human, epidemiological data, if available, are preferred as the starting point for quantitative risk analysis above the use of data from animal studies. Although methods to obtain proper risk estimates from epidemiological data are available, several impediments prevent their widespread application. These impediments include unfamiliarity with epidemiological methods and the lack of a structured and transparent approach. We described a framework to conduct quantitative cancer risk assessment based on epidemiological studies in a structured, transparent, and reproducible manner. Important features of the process include a weight-of-the-evidence approach, estimation of the optimal exposure-risk function by fitting a regression model to the epidemiological data, estimation of uncertainty introduced by potential biases and missing information in the epidemiological studies, and calculation of excess lifetime risk through a life table to take into account competing risks. Sensitivity analyses are a useful tool to obtain insight into the impact of assumptions made and the variability of the underlying data. The framework is sufficiently flexible to allow many types of data, ranging from published, sometimes incomplete data to detailed individual data, while maintaining an optimal result, i.e., a state-of-the-art risk estimate with confidence intervals, based on all available evidence of sufficient quality."
1231834,Michaels et al. 2006,Selected science: an industry campaign to undermine an OSHA hexavalent chromium standard,"While exposure to hexavalent chromium (Cr(VI)) has been associated with increased lung cancer risk for more than 50 years, the chemical is not currently regulated by the U.S. Occupational Safety and Health Administration (OSHA) on the basis of its carcinogenicity. The agency was petitioned in 1993 and sued in 1997 and 2002 to lower the workplace Cr(VI) exposure limit, resulting in a court order to issue a final standard by February 2006. Faced with the threat of stronger regulation, the chromium industry initiated an effort to challenge the scientific evidence supporting a more protective standard. This effort included the use of &quot;product defense&quot; consultants to conduct post hoc analyses of a publicly-funded study to challenge results viewed unfavorably by the industry. The industry also commissioned a study of the mortality experience of workers at four low-exposure chromium plants, but did not make the results available to OSHA in a timely manner, despite multiple agency requests for precisely these sorts of data. The commissioned study found a statistically significant elevation in lung cancer risk among Cr(VI)-exposed workers at levels far below the current standard. This finding changed when the multi-plant cohort was divided into two statistically underpowered components and then published separately. The findings of the first paper published have been used by the chromium industry to attempt to slow OSHA's standard setting process. The second paper was withheld from OSHA until it was accepted for publication in a scientific journal, after the rulemaking record had closed. Studies funded by private sponsors that seek to influence public regulatory proceedings should be subject to the same access and reporting provisions as those applied to publicly funded science. Parties in regulatory proceedings should be required to disclose whether the studies were performed by researchers who had the right to present their findings without the sponsor's consent or influence, and to certify that all relevant data have been submitted to the public record, whether published or not.","Selected science: an industry campaign to undermine an OSHA hexavalent chromium standard Abs: While exposure to hexavalent chromium (Cr(VI)) has been associated with increased lung cancer risk for more than 50 years, the chemical is not currently regulated by the U.S. Occupational Safety and Health Administration (OSHA) on the basis of its carcinogenicity. The agency was petitioned in 1993 and sued in 1997 and 2002 to lower the workplace Cr(VI) exposure limit, resulting in a court order to issue a final standard by February 2006. Faced with the threat of stronger regulation, the chromium industry initiated an effort to challenge the scientific evidence supporting a more protective standard. This effort included the use of &quot;product defense&quot; consultants to conduct post hoc analyses of a publicly-funded study to challenge results viewed unfavorably by the industry. The industry also commissioned a study of the mortality experience of workers at four low-exposure chromium plants, but did not make the results available to OSHA in a timely manner, despite multiple agency requests for precisely these sorts of data. The commissioned study found a statistically significant elevation in lung cancer risk among Cr(VI)-exposed workers at levels far below the current standard. This finding changed when the multi-plant cohort was divided into two statistically underpowered components and then published separately. The findings of the first paper published have been used by the chromium industry to attempt to slow OSHA's standard setting process. The second paper was withheld from OSHA until it was accepted for publication in a scientific journal, after the rulemaking record had closed. Studies funded by private sponsors that seek to influence public regulatory proceedings should be subject to the same access and reporting provisions as those applied to publicly funded science. Parties in regulatory proceedings should be required to disclose whether the studies were performed by researchers who had the right to present their findings without the sponsor's consent or influence, and to certify that all relevant data have been submitted to the public record, whether published or not."
1231833,Schaeffer 2006,Microbes turn waste into a nanocatalyst,,Microbes turn waste into a nanocatalyst Abs: 
1231831,Yang et al. 2005,"The stepwise process of chromium-induced DNA breakage: characterization by electrochemistry, atomic force microscopy, and DNA electrophoresis","DNA conformational change and breakage induced by Cr(VI)-GSH interaction were characterized by the integrated tools of electrochemistry, atomic force microscopy (AFM), and DNA electrophoresis. While electrochemistry confirmed the formation of the active species generated from Cr(VI)-GSH reduction, which causes the DNA conformational changes, AFM imaging vividly demonstrated the stepwise process of the DNA denaturation and breakage for the first time. Our DNA electrophoresis further validated that the DNA breakage occurs unevenly at both of the single strands of the molecule. A scheme was drawn based on the experimental observations to explain the phenomenon of the Cr-induced DNA cleavage.","The stepwise process of chromium-induced DNA breakage: characterization by electrochemistry, atomic force microscopy, and DNA electrophoresis Abs: DNA conformational change and breakage induced by Cr(VI)-GSH interaction were characterized by the integrated tools of electrochemistry, atomic force microscopy (AFM), and DNA electrophoresis. While electrochemistry confirmed the formation of the active species generated from Cr(VI)-GSH reduction, which causes the DNA conformational changes, AFM imaging vividly demonstrated the stepwise process of the DNA denaturation and breakage for the first time. Our DNA electrophoresis further validated that the DNA breakage occurs unevenly at both of the single strands of the molecule. A scheme was drawn based on the experimental observations to explain the phenomenon of the Cr-induced DNA cleavage."
1231830,Mukhopadhyay et al. 2007,Removal of Cr(VI) from Cr-contaminated groundwater through electrochemical addition of Fe(II),"The conventional chemical reduction-precipitation technique in the removal of Cr(VI) from contaminated groundwater involves a two-step process whereby Cr(VI) is first reduced to Cr(III) at an acidic pH by a reducing agent and in a subsequent step, Cr(III) is precipitated as insoluble hydroxide at an alkaline pH. In a variation of this method, Fe(II) is added electrochemically to the Cr(VI) containing water. From a pure iron electrode, Fe(2+) ions are released into the solution and bring forth the reduction of Cr(VI). At the cathode, H(2)O is reduced whereby the OH(-) ions entering the solution keep the pH of the solution in the alkaline range. This latter fact greatly facilitates simultaneous reduction of Cr(VI) to Cr(III) and co-precipitation of hydroxides of trivalent Cr and Fe. On the basis of a set of experimental data, it is shown that this process is both thermodynamically and kinetically efficient, meaning, with the electrochemical method, rapid and nearly complete removal of Cr(VI) from a groundwater source with both high and low levels of Cr-contamination can be achieved. These factors make the electrochemical process superior to the conventional chemical process in remediation of Cr-contaminated groundwater.","Removal of Cr(VI) from Cr-contaminated groundwater through electrochemical addition of Fe(II) Abs: The conventional chemical reduction-precipitation technique in the removal of Cr(VI) from contaminated groundwater involves a two-step process whereby Cr(VI) is first reduced to Cr(III) at an acidic pH by a reducing agent and in a subsequent step, Cr(III) is precipitated as insoluble hydroxide at an alkaline pH. In a variation of this method, Fe(II) is added electrochemically to the Cr(VI) containing water. From a pure iron electrode, Fe(2+) ions are released into the solution and bring forth the reduction of Cr(VI). At the cathode, H(2)O is reduced whereby the OH(-) ions entering the solution keep the pH of the solution in the alkaline range. This latter fact greatly facilitates simultaneous reduction of Cr(VI) to Cr(III) and co-precipitation of hydroxides of trivalent Cr and Fe. On the basis of a set of experimental data, it is shown that this process is both thermodynamically and kinetically efficient, meaning, with the electrochemical method, rapid and nearly complete removal of Cr(VI) from a groundwater source with both high and low levels of Cr-contamination can be achieved. These factors make the electrochemical process superior to the conventional chemical process in remediation of Cr-contaminated groundwater."
1231828,Ewis et al. 2006,Surfactant protein B gene variations and susceptibility to lung cancer in chromate workers,"<strong>BACKGROUND: </strong>Hexavalent chromium has been extensively investigated regarding its mutagenicity and carcinogenicity; however, its mechanism for initiating and enhancing the development of lung cancer is still obscure. Biomarkers of exposure, effect or susceptibility are required for risk assessment and for epidemiologic research studies especially in occupational settings. Since the surfactant protein system (SP) is very important for normal lung function and for mediating local airway conditions and in the clearance of the upper respiratory tract from the occupational and environmental dusts, we hypothesize that SP genes may represent good candidates to study susceptibility for lung cancer.<br /><br /><strong>METHODS: </strong>Using PCR genotyping methods with gel electrophoresis and confirmation of results with precise DNA fragment size measurement on microchip electrophoresis, we analyzed SP-B intron-4 polymorphism in 230 subjects who were classified into groups; chromate-related lung cancer, control chromate workers who had not developed lung cancer, control individuals with non chromate-related adenocarcinoma or squamous cell carcinoma of the lungs, or healthy Japanese control individuals.<br /><br /><strong>RESULTS: </strong>Our results indicated that the SP-B variants (deletion/insertion) were significantly overrepresented (61.3%) in the chromate-related lung cancer group than other groups (X2 = 47.6; DF = 4, P = 0.0001). There was a significant difference between the chromate lung cancer group and both of the control groups, healthy individuals and chromate workers who did not develop lung cancer, showing odds ratios (OR) with 95% confidence intervals (CI) of 21.9 (7.3-65.7) and 19.0 (3.78-95.4), respectively. Compared with 46 non chromate-related SCC of the lung, the SP-B variants were significantly overrepresented in the chromate-related SCC (18/28; 64.3%) than the non-chromate SCC (11/46; 23.9%) of the lung samples (X(2) = 10.27, P = 0.01), OR with 95% CI is 5.73 (2.05-16.01).<br /><br /><strong>CONCLUSION: </strong>These findings indicate a very strong association of the SP-B intron-4 variants with mechanisms that may enhance lung cancer susceptibility, especially in workers who are employed in chromate industry. Moreover, confirmation of such results may help to suggest adding the SP-B intron-4 typing to be one of the screening tests of the pre-placement medical examination to confirm that the worker has no variations of the SP-B gene before being engaged in a chromium-related industry, with the intention of providing proper medical counseling.","Surfactant protein B gene variations and susceptibility to lung cancer in chromate workers Abs: <strong>BACKGROUND: </strong>Hexavalent chromium has been extensively investigated regarding its mutagenicity and carcinogenicity; however, its mechanism for initiating and enhancing the development of lung cancer is still obscure. Biomarkers of exposure, effect or susceptibility are required for risk assessment and for epidemiologic research studies especially in occupational settings. Since the surfactant protein system (SP) is very important for normal lung function and for mediating local airway conditions and in the clearance of the upper respiratory tract from the occupational and environmental dusts, we hypothesize that SP genes may represent good candidates to study susceptibility for lung cancer.<br /><br /><strong>METHODS: </strong>Using PCR genotyping methods with gel electrophoresis and confirmation of results with precise DNA fragment size measurement on microchip electrophoresis, we analyzed SP-B intron-4 polymorphism in 230 subjects who were classified into groups; chromate-related lung cancer, control chromate workers who had not developed lung cancer, control individuals with non chromate-related adenocarcinoma or squamous cell carcinoma of the lungs, or healthy Japanese control individuals.<br /><br /><strong>RESULTS: </strong>Our results indicated that the SP-B variants (deletion/insertion) were significantly overrepresented (61.3%) in the chromate-related lung cancer group than other groups (X2 = 47.6; DF = 4, P = 0.0001). There was a significant difference between the chromate lung cancer group and both of the control groups, healthy individuals and chromate workers who did not develop lung cancer, showing odds ratios (OR) with 95% confidence intervals (CI) of 21.9 (7.3-65.7) and 19.0 (3.78-95.4), respectively. Compared with 46 non chromate-related SCC of the lung, the SP-B variants were significantly overrepresented in the chromate-related SCC (18/28; 64.3%) than the non-chromate SCC (11/46; 23.9%) of the lung samples (X(2) = 10.27, P = 0.01), OR with 95% CI is 5.73 (2.05-16.01).<br /><br /><strong>CONCLUSION: </strong>These findings indicate a very strong association of the SP-B intron-4 variants with mechanisms that may enhance lung cancer susceptibility, especially in workers who are employed in chromate industry. Moreover, confirmation of such results may help to suggest adding the SP-B intron-4 typing to be one of the screening tests of the pre-placement medical examination to confirm that the worker has no variations of the SP-B gene before being engaged in a chromium-related industry, with the intention of providing proper medical counseling."
1231827,Wei and  Hsieh 2006,Effect of humic substance on thermal treatment of chromium(VI)-containing latosol soil,"Latosol soils contaminated with chromium(VI) [Cr(VI)], which is hazardous, can be recycled as raw materials for porcelain and construction sectors if a proper thermal stabilization process is implemented. This study investigates how thermal treatment affects Cr behavior during the sintering of latosol and deorganic latosol samples; both samples are artificially contaminated with CrO3. Approaches including X-ray absorption spectroscopy, scanning electron microscopy, N2-based Brunauer Emmett Teller surface analyzer, thermogravimetric analyzer/differential scanning calorimeter, and the toxicity characteristic leaching procedure promulgated by Taiwan Environmental Protection Administration are used in this study. After drying the Cr(VI)-contaminated latosol (i.e., containing 37,120 mg of Cr/kg sample) at 105 degrees C, approximately 80% of the doped CrO3 is chemically reduced to Cr(OH)3 by a humic substance naturally existing in the soil. In contrast, in the organics-free CrO3-contaminated latosol dried at 105 degrees C, only 9% of the doped CrO3 is reduced to Cr(OH)3. Heating the samples at 500 and 1100 degrees C transforms hazardous Cr(VI) into Cr(III) that is negligibly toxic; Cr2O3, which is insoluble, is detected as the most abundant Cr species. Moreover, formation of Cr2SiOs, which is suggested to relate to low Cr leaching, is only detected in the sample heated at 1100 degrees C. Surface morphology, surface area, and thermogravimetric analyzer/differential scanning calorimeter results demonstrate that thermal treatment at 1100 degrees C can incur considerable soil sintering/ melting if the humic substance in the soil has been heated off previously. Finally, Cr concentrations in the toxicity characteristic leaching procedure leachates collected from the samples thermally treated at 1100 degrees C for 4 hr are &lt; or =0.21 mg of Cr L(-1) that are much less than the Taiwan Environmental Protection Administration regulatory limit (&lt;5 mg of Cr L(-1)); consequently, these two samples are nonhazardous, and they have the potential for resource recycling. Conversely, Cr concentrations in the leachates from all 500 degrees C and 105 degrees C samples are in the 25.6-1279 mg L(-1) range.","Effect of humic substance on thermal treatment of chromium(VI)-containing latosol soil Abs: Latosol soils contaminated with chromium(VI) [Cr(VI)], which is hazardous, can be recycled as raw materials for porcelain and construction sectors if a proper thermal stabilization process is implemented. This study investigates how thermal treatment affects Cr behavior during the sintering of latosol and deorganic latosol samples; both samples are artificially contaminated with CrO3. Approaches including X-ray absorption spectroscopy, scanning electron microscopy, N2-based Brunauer Emmett Teller surface analyzer, thermogravimetric analyzer/differential scanning calorimeter, and the toxicity characteristic leaching procedure promulgated by Taiwan Environmental Protection Administration are used in this study. After drying the Cr(VI)-contaminated latosol (i.e., containing 37,120 mg of Cr/kg sample) at 105 degrees C, approximately 80% of the doped CrO3 is chemically reduced to Cr(OH)3 by a humic substance naturally existing in the soil. In contrast, in the organics-free CrO3-contaminated latosol dried at 105 degrees C, only 9% of the doped CrO3 is reduced to Cr(OH)3. Heating the samples at 500 and 1100 degrees C transforms hazardous Cr(VI) into Cr(III) that is negligibly toxic; Cr2O3, which is insoluble, is detected as the most abundant Cr species. Moreover, formation of Cr2SiOs, which is suggested to relate to low Cr leaching, is only detected in the sample heated at 1100 degrees C. Surface morphology, surface area, and thermogravimetric analyzer/differential scanning calorimeter results demonstrate that thermal treatment at 1100 degrees C can incur considerable soil sintering/ melting if the humic substance in the soil has been heated off previously. Finally, Cr concentrations in the toxicity characteristic leaching procedure leachates collected from the samples thermally treated at 1100 degrees C for 4 hr are &lt; or =0.21 mg of Cr L(-1) that are much less than the Taiwan Environmental Protection Administration regulatory limit (&lt;5 mg of Cr L(-1)); consequently, these two samples are nonhazardous, and they have the potential for resource recycling. Conversely, Cr concentrations in the leachates from all 500 degrees C and 105 degrees C samples are in the 25.6-1279 mg L(-1) range."
1231826,Atli et al. 2006,"Response of catalase activity to Ag+, Cd2+, Cr6+, Cu2+ and Zn2+ in five tissues of freshwater fish Oreochromis niloticus","Catalase (CAT, EC 1.11.1.6) is an important enzyme in antioxidant defense system protecting animals from oxidative stress. Freshwater fish Oreochromis niloticus were exposed for 96 h to different concentrations of Ag(+), Cd(2+), Cr(6+), Cu(2+) and Zn(2+), known to cause oxidative stress, and subsequently CAT activities in liver, kidney, gill, intestine and brain were measured. In vivo, CAT was stimulated by all metals except Ag(+) in the liver and the highest increase in CAT activity (183%) resulted from 1.0 mg Cd(2+)/L exposure, whereas 0.5 mg Ag(+)/L exposure resulted in a sharp decrease (44%). In tilapia kidney, cadmium and zinc had no significant effects on CAT activity, whereas 0.1 mg Cr(6+)/L exposure caused a decrease (44%). Cadmium and zinc did not significantly affect the CAT activity in gill; however, 0.5 mg Ag(+)/L exposure caused an increase (66%) and 1.5 mg Cr(6+)/L exposure caused a decrease (97%) in CAT activity. All metals, except Cu(2+)(41% increase), caused significant decreases in CAT activity in the intestine. In brain, 1.0 mg Zn(2+)/L resulted in an increase in CAT activity (126%), while 1.5 mg Ag(+)/L exposure caused a 54% decrease. In vitro, all metals -- except Ag(+) and Cu(2+) in kidney -- significantly inhibited the CAT activity in all tissues. Results emphasized that CAT may be considered as a sensitive bioindicator of the antioxidant defense system.","Response of catalase activity to Ag+, Cd2+, Cr6+, Cu2+ and Zn2+ in five tissues of freshwater fish Oreochromis niloticus Abs: Catalase (CAT, EC 1.11.1.6) is an important enzyme in antioxidant defense system protecting animals from oxidative stress. Freshwater fish Oreochromis niloticus were exposed for 96 h to different concentrations of Ag(+), Cd(2+), Cr(6+), Cu(2+) and Zn(2+), known to cause oxidative stress, and subsequently CAT activities in liver, kidney, gill, intestine and brain were measured. In vivo, CAT was stimulated by all metals except Ag(+) in the liver and the highest increase in CAT activity (183%) resulted from 1.0 mg Cd(2+)/L exposure, whereas 0.5 mg Ag(+)/L exposure resulted in a sharp decrease (44%). In tilapia kidney, cadmium and zinc had no significant effects on CAT activity, whereas 0.1 mg Cr(6+)/L exposure caused a decrease (44%). Cadmium and zinc did not significantly affect the CAT activity in gill; however, 0.5 mg Ag(+)/L exposure caused an increase (66%) and 1.5 mg Cr(6+)/L exposure caused a decrease (97%) in CAT activity. All metals, except Cu(2+)(41% increase), caused significant decreases in CAT activity in the intestine. In brain, 1.0 mg Zn(2+)/L resulted in an increase in CAT activity (126%), while 1.5 mg Ag(+)/L exposure caused a 54% decrease. In vitro, all metals -- except Ag(+) and Cu(2+) in kidney -- significantly inhibited the CAT activity in all tissues. Results emphasized that CAT may be considered as a sensitive bioindicator of the antioxidant defense system."
1231825,Prabakaran et al. 2006,Immune response and disease resistance of Oreochromis mossambicus to Aeromonas hydrophila after exposure to hexavalent chromium,"The objective of this study was to investigate the effect of chronic exposure to sublethal concentrations of hexavalent chromium (K2Cr2O7) on the immune response and disease resistance of Oreochromis mossambicus (Peters) to bacterial Aeromonas hydrophila infection. Fish (45 to 50 g) were exposed to 0.005, 0.05, 0.5, and 5 mg l(-1) [0.01, 0.1, 1, and 10% LC50, respectively] of hexavalent chromium Cr (VI) for 28 d. The specific immune response was assessed by antibody response to A. hydrophila by bacterial agglutination assay, and to sheep red blood cells (SRBC) by plaque forming cell (PFC) assay. In addition, nonspecific immune mechanisms were assessed by serum lysozyme activity and reactive nitrogen intermediates, the latter in terms of nitric oxide (NO) production by peripheral blood leucocytes. Overall immunity was assessed by disease resistance against live virulent A. hydrophila. The study clearly indicated that chronic exposure of fish to 0.5 and 5 mg l(-1) of chromium (VI) decreased both nonspecific and specific parameters of the immune system, which resulted in a lower disease resistance to A. hydrophila. Interestingly, 0.05 mg l(-1) of Cr (VI) enhanced disease resistance and both nonspecific and specific immune responses to A. hydrophila. Our study revealed a concentration-dependent modulation of the immune system by chromium (VI), as demonstrated by suppressive or stimulatory effects on lymphocytes, lysozyme, phagocytic killing mechanisms, and disease resistance in O. mossambicus.","Immune response and disease resistance of Oreochromis mossambicus to Aeromonas hydrophila after exposure to hexavalent chromium Abs: The objective of this study was to investigate the effect of chronic exposure to sublethal concentrations of hexavalent chromium (K2Cr2O7) on the immune response and disease resistance of Oreochromis mossambicus (Peters) to bacterial Aeromonas hydrophila infection. Fish (45 to 50 g) were exposed to 0.005, 0.05, 0.5, and 5 mg l(-1) [0.01, 0.1, 1, and 10% LC50, respectively] of hexavalent chromium Cr (VI) for 28 d. The specific immune response was assessed by antibody response to A. hydrophila by bacterial agglutination assay, and to sheep red blood cells (SRBC) by plaque forming cell (PFC) assay. In addition, nonspecific immune mechanisms were assessed by serum lysozyme activity and reactive nitrogen intermediates, the latter in terms of nitric oxide (NO) production by peripheral blood leucocytes. Overall immunity was assessed by disease resistance against live virulent A. hydrophila. The study clearly indicated that chronic exposure of fish to 0.5 and 5 mg l(-1) of chromium (VI) decreased both nonspecific and specific parameters of the immune system, which resulted in a lower disease resistance to A. hydrophila. Interestingly, 0.05 mg l(-1) of Cr (VI) enhanced disease resistance and both nonspecific and specific immune responses to A. hydrophila. Our study revealed a concentration-dependent modulation of the immune system by chromium (VI), as demonstrated by suppressive or stimulatory effects on lymphocytes, lysozyme, phagocytic killing mechanisms, and disease resistance in O. mossambicus."
1231824,Cao and  Zhang 2006,Stabilization of chromium ore processing residue (COPR) with nanoscale iron particles,"Laboratory batch experiments were conducted on heavily contaminated groundwater and chromium ore processing residue (COPR) samples to determine the rate and extent of hexavalent chromium [Cr(VI)] reduction and immobilization by nanoscale iron particles. Laboratory synthesized nanoscale iron particles (&lt;100 nm, specific surface area 35 m(2)/g) were used for this work. Groundwater ([Cr(VI)]=42.83 +/- 0.52 mg/L, pH 11.0+/-0.5) and COPR samples ([Cr(VI)] = 3280 +/- 90 mg/kg) were collected from an industrial site in New Jersey. Cr(VI) in the water and COPR samples was quickly reduced and precipitated out of the aqueous solution. The surface area normalized reaction rate constant of Cr(VI) reduction by nanoscale iron particles was 0.157 +/- 0.018 mg m(-2) min(-1), about 25 times greater than that by iron powders (100 mesh). One gram of nanoparticles can reduce 84.4-109.3mg Cr(VI) in the groundwater and 69.3-72.7 mg Cr(VI) in the COPR. This reduction capacity is 50-70 times greater than that of iron powders under the same experimental conditions.","Stabilization of chromium ore processing residue (COPR) with nanoscale iron particles Abs: Laboratory batch experiments were conducted on heavily contaminated groundwater and chromium ore processing residue (COPR) samples to determine the rate and extent of hexavalent chromium [Cr(VI)] reduction and immobilization by nanoscale iron particles. Laboratory synthesized nanoscale iron particles (&lt;100 nm, specific surface area 35 m(2)/g) were used for this work. Groundwater ([Cr(VI)]=42.83 +/- 0.52 mg/L, pH 11.0+/-0.5) and COPR samples ([Cr(VI)] = 3280 +/- 90 mg/kg) were collected from an industrial site in New Jersey. Cr(VI) in the water and COPR samples was quickly reduced and precipitated out of the aqueous solution. The surface area normalized reaction rate constant of Cr(VI) reduction by nanoscale iron particles was 0.157 +/- 0.018 mg m(-2) min(-1), about 25 times greater than that by iron powders (100 mesh). One gram of nanoparticles can reduce 84.4-109.3mg Cr(VI) in the groundwater and 69.3-72.7 mg Cr(VI) in the COPR. This reduction capacity is 50-70 times greater than that of iron powders under the same experimental conditions."
1231823,Neelavathi et al. 2004,Removal of toxic Cr(VI) by the adsorption of activated carbons prepared from Simarouba shells,"Removal of toxic Cr(VI) in aqueous medium was investigated using activated carbon adsorbents prepared from Simarouba glauca seed shells. The pH effect, Cr(VI) concentration, adsorbent dosage and contact time period were studied in batch experiment. The removal of Cr(VI) was in general most effective at pH range 2.0-4.0 and high Cr(VI) concentrations. Activated carbons are prepared at 80050 degrees C temperature. One is non-impregnated and the remaining three are impregnated with zinc chloride in 1:1,1:2,1:3 ratio. Important characteristics of activated carbons are also investigated. The data for all the adsorbents fit well to the Freundlich adsorption isotherm. The removal of Cr(VI) is around 97% was observed with 1:2 impregnated activated carbon at pH 3.0 where as other adsorbents showed much lower activities.","Removal of toxic Cr(VI) by the adsorption of activated carbons prepared from Simarouba shells Abs: Removal of toxic Cr(VI) in aqueous medium was investigated using activated carbon adsorbents prepared from Simarouba glauca seed shells. The pH effect, Cr(VI) concentration, adsorbent dosage and contact time period were studied in batch experiment. The removal of Cr(VI) was in general most effective at pH range 2.0-4.0 and high Cr(VI) concentrations. Activated carbons are prepared at 80050 degrees C temperature. One is non-impregnated and the remaining three are impregnated with zinc chloride in 1:1,1:2,1:3 ratio. Important characteristics of activated carbons are also investigated. The data for all the adsorbents fit well to the Freundlich adsorption isotherm. The removal of Cr(VI) is around 97% was observed with 1:2 impregnated activated carbon at pH 3.0 where as other adsorbents showed much lower activities."
1231822,Rocchetta et al. 2006,Chromium toxicity to Euglena gracilis strains depending on the physiocochemical properties of the culture medium,,Chromium toxicity to Euglena gracilis strains depending on the physiocochemical properties of the culture medium Abs: 
1231821,Kang et al. 2006,Determination of hexavalent chromium in cosmetic products by ion chromatography and postcolumn derivatization,"Chromium hydroxide green [Cr(2)O(OH)(4)] and chromium oxide green (Cr(2)O(3)) are colouring agents for use in cosmetic products. These colourants may contain chromium (VI), which cause skin allergies through percutaneous adsorption on the skin. Eye shadow is a representative cosmetic product in which significant colourants are used. We analysed the chromium (VI) in the eye shadows by ion chromatography and post column derivatization. We optimize conditions of chromium (VI) analysis in eye shadows. During the pretreatment procedure, there are no exchange of chromium (III) to chromium (VI). This method has a limit of quantification for chromium (VI) of 1.0 microg l(-1), recovery rate of 100 +/- 3% and analysis time less than 10 min. This result is 300 times more sensitive than the high-performance liquid chromatography method. We applied the optimized method to analyse 22 eye shadows and 6 colouring agents. 2 out of 22 of the products contained more than 5 mg l(-1). In our previous work, 5 mg l(-1) of Cr represented a threshold level. There was much more Cr(VI) in the colouring agents. The Cr(VI) in one of the colouring agents was 97.6 mg l(-1).","Determination of hexavalent chromium in cosmetic products by ion chromatography and postcolumn derivatization Abs: Chromium hydroxide green [Cr(2)O(OH)(4)] and chromium oxide green (Cr(2)O(3)) are colouring agents for use in cosmetic products. These colourants may contain chromium (VI), which cause skin allergies through percutaneous adsorption on the skin. Eye shadow is a representative cosmetic product in which significant colourants are used. We analysed the chromium (VI) in the eye shadows by ion chromatography and post column derivatization. We optimize conditions of chromium (VI) analysis in eye shadows. During the pretreatment procedure, there are no exchange of chromium (III) to chromium (VI). This method has a limit of quantification for chromium (VI) of 1.0 microg l(-1), recovery rate of 100 +/- 3% and analysis time less than 10 min. This result is 300 times more sensitive than the high-performance liquid chromatography method. We applied the optimized method to analyse 22 eye shadows and 6 colouring agents. 2 out of 22 of the products contained more than 5 mg l(-1). In our previous work, 5 mg l(-1) of Cr represented a threshold level. There was much more Cr(VI) in the colouring agents. The Cr(VI) in one of the colouring agents was 97.6 mg l(-1)."
1231820,Egilman and  Scout 2006,Corporate corruption of science--the case of chromium(VI),"Corporate infiltration of a panel convened to set standards for chromium(VI) in California, buttressed by the engineered production of dubious &quot;scientific&quot; literature advancing industry's goal, succeeded in skewing the panel's decision to protect industry profits rather than public health. This situation demonstrates the insidious and effective influence of industry on the regulatory process.","Corporate corruption of science--the case of chromium(VI) Abs: Corporate infiltration of a panel convened to set standards for chromium(VI) in California, buttressed by the engineered production of dubious &quot;scientific&quot; literature advancing industry's goal, succeeded in skewing the panel's decision to protect industry profits rather than public health. This situation demonstrates the insidious and effective influence of industry on the regulatory process."
1231818,Vutukuru 2005,"Acute effects of hexavalent chromium on survival, oxygen consumption, hematological parameters and some biochemical profiles of the Indian major carp, Labeo rohita","An attempt has been made in the present investigation to determine the acute toxicity of hexavalent chromium and its toxicological effects on survival, physiological, hematological and biochemical parameters of the widely consumed Indian major carp, Labeo rohita. Short-term acute toxicity tests were performed adopting renewal bioassay technique (USEPA, 1975) over a period of 96 h, using different concentrations of potassium dichromate to the fish and the 96 h LC[50] value was found to be 111.45 mg/l (Cr(+6) as 39.40 mg/l). ANOVA results showed that the normal respiratory activity of the fish was significantly affected and there is a depression in the metabolic rate at the end of 24, 48, 72 and 96 h exposure. The metal also induced significant decrease (p&lt;0.001) in the hematological parameters of the fish like total erythrocyte count, hemoglobin percent and absolute value Mean cell hemoglobin (MCH) both at the end of 24h and 96 h exposure indicating anemia. Appreciable decline in the biochemical profiles such as total glycogen, total lipids and total protein contents of the fish was also observed. However, the decrease in protein content was significant only at the end of 96 h. This study reflects the extent of the toxic effects of hexavalent chromium and the metal induced cumulative deleterious effects at various functional levels in the widely consumed freshwater fish, Labeo rohita.","Acute effects of hexavalent chromium on survival, oxygen consumption, hematological parameters and some biochemical profiles of the Indian major carp, Labeo rohita Abs: An attempt has been made in the present investigation to determine the acute toxicity of hexavalent chromium and its toxicological effects on survival, physiological, hematological and biochemical parameters of the widely consumed Indian major carp, Labeo rohita. Short-term acute toxicity tests were performed adopting renewal bioassay technique (USEPA, 1975) over a period of 96 h, using different concentrations of potassium dichromate to the fish and the 96 h LC[50] value was found to be 111.45 mg/l (Cr(+6) as 39.40 mg/l). ANOVA results showed that the normal respiratory activity of the fish was significantly affected and there is a depression in the metabolic rate at the end of 24, 48, 72 and 96 h exposure. The metal also induced significant decrease (p&lt;0.001) in the hematological parameters of the fish like total erythrocyte count, hemoglobin percent and absolute value Mean cell hemoglobin (MCH) both at the end of 24h and 96 h exposure indicating anemia. Appreciable decline in the biochemical profiles such as total glycogen, total lipids and total protein contents of the fish was also observed. However, the decrease in protein content was significant only at the end of 96 h. This study reflects the extent of the toxic effects of hexavalent chromium and the metal induced cumulative deleterious effects at various functional levels in the widely consumed freshwater fish, Labeo rohita."
1231817,Shukla and  Rai 2006,Hexavalent chromium induced changes in growth and biochemical responses of chromate-resistant bacterial strains isolated from tannery effluent,,Hexavalent chromium induced changes in growth and biochemical responses of chromate-resistant bacterial strains isolated from tannery effluent Abs: 
1231816,Park et al. 2007,Kinetics of the reduction of hexavalent chromium with the brown seaweed Ecklonia biomass,"The dead biomass of the brown seaweed, Ecklonia sp., is capable of reducing toxic Cr(VI) into less toxic or nontoxic Cr(III). However, little is known about the mechanism of Cr(VI) reduction by the biomass. The objective of this work was to develop a kinetic model for Cr(VI) biosorption, for supporting our mechanism. The reduction rate of Cr(VI) increased with increasing total chromate concentration, [Cr(VI)], and equivalent concentration of organic compounds, [OCs], and decreasing solution pH. It was found that the reduction rate of Cr(VI) was proportional to [Cr(VI)] and [OCs], suggesting the simple kinetic equation -d[Cr(VI)]/dt=k[Cr(VI)][OCs]. When considering the consumption of organic compounds due to the oxidation by Cr(VI), an average rate coefficient of 9.33 (+/-0.65)microM(-1)h(-1) was determined, at pH 2. Although the function of the pH could not be expressed in a mechanistic manner, an empirical model able to describe the pH dependence was obtained. It is expected that the developed rate equation could likely be used for design and performance predictions of biosorption processes for treating chromate wastewaters.","Kinetics of the reduction of hexavalent chromium with the brown seaweed Ecklonia biomass Abs: The dead biomass of the brown seaweed, Ecklonia sp., is capable of reducing toxic Cr(VI) into less toxic or nontoxic Cr(III). However, little is known about the mechanism of Cr(VI) reduction by the biomass. The objective of this work was to develop a kinetic model for Cr(VI) biosorption, for supporting our mechanism. The reduction rate of Cr(VI) increased with increasing total chromate concentration, [Cr(VI)], and equivalent concentration of organic compounds, [OCs], and decreasing solution pH. It was found that the reduction rate of Cr(VI) was proportional to [Cr(VI)] and [OCs], suggesting the simple kinetic equation -d[Cr(VI)]/dt=k[Cr(VI)][OCs]. When considering the consumption of organic compounds due to the oxidation by Cr(VI), an average rate coefficient of 9.33 (+/-0.65)microM(-1)h(-1) was determined, at pH 2. Although the function of the pH could not be expressed in a mechanistic manner, an empirical model able to describe the pH dependence was obtained. It is expected that the developed rate equation could likely be used for design and performance predictions of biosorption processes for treating chromate wastewaters."
1231815,Deng et al. 2006,"Photoreduction of chromium(VI) in the presence of algae, Chlorella vulgaris","In this thesis, the photochemical reduction of hexavalent chromium Cr(VI) in the presence of algae, Chlorella vulgaris, was investigated under the irradiation of metal halide lamps (lambda = 365 nm, 250 W). The affecting factors of photochemical reduction were studied in detail, such as exposure time, initial Cr(VI) concentration, initial algae concentration and pH. The rate of Cr(VI) photochemical reduction increased with algae concentration increasing, exposure time increasing, initial Cr(VI) concentration decreasing and the decrease of pH. When pH increased to 6, the rate of Cr(VI) photochemical reduction nearly vanished. When initial Cr(VI) concentration ranged from 0.4 to 1.0 mg L(-1) and initial algae concentration ranged from ABS(algae) (the absorbency of algae) = 0.025 to ABS(algae) = 0.180, According to the results of kinetic analyses, the kinetic equation of Cr(VI) photochemical reduction in aqueous solution with algae under 250 W metal halide lamps was V0 = kC(0)(0.1718)A(algae)(0.5235) (C0 was initial concentration of Cr(VI); A(algae) was initial concentration of algae) under the condition of pH 4.","Photoreduction of chromium(VI) in the presence of algae, Chlorella vulgaris Abs: In this thesis, the photochemical reduction of hexavalent chromium Cr(VI) in the presence of algae, Chlorella vulgaris, was investigated under the irradiation of metal halide lamps (lambda = 365 nm, 250 W). The affecting factors of photochemical reduction were studied in detail, such as exposure time, initial Cr(VI) concentration, initial algae concentration and pH. The rate of Cr(VI) photochemical reduction increased with algae concentration increasing, exposure time increasing, initial Cr(VI) concentration decreasing and the decrease of pH. When pH increased to 6, the rate of Cr(VI) photochemical reduction nearly vanished. When initial Cr(VI) concentration ranged from 0.4 to 1.0 mg L(-1) and initial algae concentration ranged from ABS(algae) (the absorbency of algae) = 0.025 to ABS(algae) = 0.180, According to the results of kinetic analyses, the kinetic equation of Cr(VI) photochemical reduction in aqueous solution with algae under 250 W metal halide lamps was V0 = kC(0)(0.1718)A(algae)(0.5235) (C0 was initial concentration of Cr(VI); A(algae) was initial concentration of algae) under the condition of pH 4."
1231814,Insel et al. 2006,Unified basis for the respirometric evaluation of inhibition for activated sludge,"This paper explores the merit of the oxygen uptake rate (OUR) profile obtained by means of respirometry as the basic mechanistic instrument for evaluating activated sludge inhibition. Experimental OUR data are generated using the synthetic peptone-based substrate and inhibition is tested with 60 mg/L hexavalent chromium and 33 mg/L nickel additions, corresponding to EC50 levels determined using the standard ISO 8192 procedure. Experimental results are evaluated by model calibration using ASM1 modified for dual hydrolysis and ASM3 modified for simultaneous growth. Model evaluations indicate that inhibition affects not only growth, but also other significant microbial mechanisms such as substrate storage and hydrolysis, leading to conclude that the proposed approach will enable to visualize the overall impact of the inhibitory compound on every stage of substrate biodegradation, through inspection and evaluation of the entire OUR profile.","Unified basis for the respirometric evaluation of inhibition for activated sludge Abs: This paper explores the merit of the oxygen uptake rate (OUR) profile obtained by means of respirometry as the basic mechanistic instrument for evaluating activated sludge inhibition. Experimental OUR data are generated using the synthetic peptone-based substrate and inhibition is tested with 60 mg/L hexavalent chromium and 33 mg/L nickel additions, corresponding to EC50 levels determined using the standard ISO 8192 procedure. Experimental results are evaluated by model calibration using ASM1 modified for dual hydrolysis and ASM3 modified for simultaneous growth. Model evaluations indicate that inhibition affects not only growth, but also other significant microbial mechanisms such as substrate storage and hydrolysis, leading to conclude that the proposed approach will enable to visualize the overall impact of the inhibitory compound on every stage of substrate biodegradation, through inspection and evaluation of the entire OUR profile."
1231813,Oliveira et al. 2006,Histopathological effects of hexavalent chronium in mouse kidney,,Histopathological effects of hexavalent chronium in mouse kidney Abs: 
1231812,Rani et al. 2006,Removal of Cr (VI) from aqueous solutions by Acacia nilotica bark,"Removal of hexavalent Cr from aqueous solutions by bark of Acacia nilotica L. was studied in batch process. Different parameters of adsorption viz. effect of pH, effect of dose and effect of contact time were studied. The percentage removal of Cr (VI) from synthetic sample was found to be 89.0 and 93.1% for 1.0 mm and 0.3 mm Acacia bark carbon (ABC) respectively and 60.9% and 68.1% for 1.0 mm and 0.3 mm Acacia bark untreated (ABU) respectively, in 30 min contact time. The optimum pH for both adsorbents was found to be 2.0 and adsorption equilibrium was found to be 30 min. for both adsorbents. The adsorption process was found to follow first order rate mechanism as well as Freundlich isotherm.","Removal of Cr (VI) from aqueous solutions by Acacia nilotica bark Abs: Removal of hexavalent Cr from aqueous solutions by bark of Acacia nilotica L. was studied in batch process. Different parameters of adsorption viz. effect of pH, effect of dose and effect of contact time were studied. The percentage removal of Cr (VI) from synthetic sample was found to be 89.0 and 93.1% for 1.0 mm and 0.3 mm Acacia bark carbon (ABC) respectively and 60.9% and 68.1% for 1.0 mm and 0.3 mm Acacia bark untreated (ABU) respectively, in 30 min contact time. The optimum pH for both adsorbents was found to be 2.0 and adsorption equilibrium was found to be 30 min. for both adsorbents. The adsorption process was found to follow first order rate mechanism as well as Freundlich isotherm."
1231811,Cokgor et al. 2007,Critical appraisal of respirometric methods for metal inhibition on activated sludge,"This paper evaluates the merit of oxygen uptake rate measurements for the assessment of metal inhibition on activated sludge. For this purpose, experiments are conducted to calculate EC50 levels of nickel and hexavalent chromium using the ISO 8192 procedure, yielding results that are highly variable and difficult to correlate, depending on the type of substrate and the initial food to microorganism ratio. Similar experiments based on continuous respirometric measurements to give the entire oxygen uptake rate profile provide a much better insight on the impact of inhibition on different biochemical processes taking place in the reactor. The results indicate that percent reduction of the amount of dissolved oxygen utilized after an appropriate reaction time is a much better index for the assessment of the inhibitory effects.","Critical appraisal of respirometric methods for metal inhibition on activated sludge Abs: This paper evaluates the merit of oxygen uptake rate measurements for the assessment of metal inhibition on activated sludge. For this purpose, experiments are conducted to calculate EC50 levels of nickel and hexavalent chromium using the ISO 8192 procedure, yielding results that are highly variable and difficult to correlate, depending on the type of substrate and the initial food to microorganism ratio. Similar experiments based on continuous respirometric measurements to give the entire oxygen uptake rate profile provide a much better insight on the impact of inhibition on different biochemical processes taking place in the reactor. The results indicate that percent reduction of the amount of dissolved oxygen utilized after an appropriate reaction time is a much better index for the assessment of the inhibitory effects."
1231810,Oh et al. 2007,Effect of amorphous silica and silica sand on removal of chromium(VI) by zero-valent iron,"The effect of two surfaces (amorphous silica and silica sand) on the reduction of chromium(VI) by zero-valent iron (Fe(0)) was investigated using batch reactors. The amendment of both surfaces significantly increased the rate and extent of Cr(VI) removal. The rate enhancement by amended surfaces is presumed to result from scavenging of Fe(0)-Cr(VI) reaction products by the provided surfaces, which minimized surface deactivation of Fe(0). The rate enhancing effect was greater for silica compared to sand, and the difference is attributed to silica's higher surface area, greater affinity for reaction products and pH buffering effect. For a given mass of Fe(0), the reactivity and longevity of Fe(0) to treat Cr(VI) increased with increasing dose of silica. Elemental analyses of the reacted iron and silica revealed that chromium removed from the solution was associated with both surfaces, with its mass distribution being approximately 1:1 per mass of iron and silica. The overall result suggests reductive precipitation was a predominant Cr(VI) removal pathway, which involves initial reduction of Cr(VI) to Cr(III), followed by formation of Cr(III)/Fe(III) hydroxides precipitates.","Effect of amorphous silica and silica sand on removal of chromium(VI) by zero-valent iron Abs: The effect of two surfaces (amorphous silica and silica sand) on the reduction of chromium(VI) by zero-valent iron (Fe(0)) was investigated using batch reactors. The amendment of both surfaces significantly increased the rate and extent of Cr(VI) removal. The rate enhancement by amended surfaces is presumed to result from scavenging of Fe(0)-Cr(VI) reaction products by the provided surfaces, which minimized surface deactivation of Fe(0). The rate enhancing effect was greater for silica compared to sand, and the difference is attributed to silica's higher surface area, greater affinity for reaction products and pH buffering effect. For a given mass of Fe(0), the reactivity and longevity of Fe(0) to treat Cr(VI) increased with increasing dose of silica. Elemental analyses of the reacted iron and silica revealed that chromium removed from the solution was associated with both surfaces, with its mass distribution being approximately 1:1 per mass of iron and silica. The overall result suggests reductive precipitation was a predominant Cr(VI) removal pathway, which involves initial reduction of Cr(VI) to Cr(III), followed by formation of Cr(III)/Fe(III) hydroxides precipitates."
1231809,De Flora et al. 2006,Oral chromium(VI) does not affect the frequency of micronuclei in hematopoietic cells of adult mice and of transplacentally exposed fetuses,"Chromium(VI) compounds are genotoxic in a variety of cellular systems. Their potential carcinogenicity is affected by toxicokinetic patterns restricting bioavailability to certain targets, and by metabolic pathways affecting interaction of chromate-derived reactive species with DNA. Epidemiological data indicate that chromium(VI) can be carcinogenic to the human respiratory tract following inhalation at doses that are only achieved in certain occupational settings. However, concern has been raised that adverse effects may also result from oral intake. In order to further explore this issue, we performed studies in BDF1 and Swiss mice of both genders and various age. Sodium dichromate dihydrate and potassium dichromate were administered either with the drinking water, up to a concentration of 500 mg chromium(VI)/l for up to 210 consecutive days, or in a single intragastric dose of 17.7 mg/kg body weight. Under these conditions, no increase of the micronucleus frequency was observed in either bone marrow or peripheral blood erythrocytes. Conversely, the same compounds induced a clastogenic damage following intraperitoneal injection, which by-passes detoxification mechanisms. In addition, due to the hypothesis that susceptibility may be increased during the period of embryogenesis, we treated pregnant mice, up to a concentration of 10mg chromium(VI)/l drinking water. There was no effect on the numbers of fetuses/dam and on body weight of fetuses. Again, no toxic or genotoxic effect was observed either in bone marrow of pregnant mice or in liver and peripheral blood of their fetuses. Thus, even at doses that largely exceed drinking water standards (up to 10,000 times) or by massive intragastric administration, chromium(VI) is not genotoxic to hematopoietic cells of either adult mice or transplacentally exposed fetuses. These conclusions are consistent with the poor toxicity and lack of carcinogenicity of oral chromium(VI), and are mechanistically explained by the high efficiency of chromium(VI) detoxification processes in the gastrointestinal tract.","Oral chromium(VI) does not affect the frequency of micronuclei in hematopoietic cells of adult mice and of transplacentally exposed fetuses Abs: Chromium(VI) compounds are genotoxic in a variety of cellular systems. Their potential carcinogenicity is affected by toxicokinetic patterns restricting bioavailability to certain targets, and by metabolic pathways affecting interaction of chromate-derived reactive species with DNA. Epidemiological data indicate that chromium(VI) can be carcinogenic to the human respiratory tract following inhalation at doses that are only achieved in certain occupational settings. However, concern has been raised that adverse effects may also result from oral intake. In order to further explore this issue, we performed studies in BDF1 and Swiss mice of both genders and various age. Sodium dichromate dihydrate and potassium dichromate were administered either with the drinking water, up to a concentration of 500 mg chromium(VI)/l for up to 210 consecutive days, or in a single intragastric dose of 17.7 mg/kg body weight. Under these conditions, no increase of the micronucleus frequency was observed in either bone marrow or peripheral blood erythrocytes. Conversely, the same compounds induced a clastogenic damage following intraperitoneal injection, which by-passes detoxification mechanisms. In addition, due to the hypothesis that susceptibility may be increased during the period of embryogenesis, we treated pregnant mice, up to a concentration of 10mg chromium(VI)/l drinking water. There was no effect on the numbers of fetuses/dam and on body weight of fetuses. Again, no toxic or genotoxic effect was observed either in bone marrow of pregnant mice or in liver and peripheral blood of their fetuses. Thus, even at doses that largely exceed drinking water standards (up to 10,000 times) or by massive intragastric administration, chromium(VI) is not genotoxic to hematopoietic cells of either adult mice or transplacentally exposed fetuses. These conclusions are consistent with the poor toxicity and lack of carcinogenicity of oral chromium(VI), and are mechanistically explained by the high efficiency of chromium(VI) detoxification processes in the gastrointestinal tract."
1231808,Wakeman and  Xu 2006,ATR regulates hexavalent chromium-induced S-phase checkpoint through phosphorylation of SMC1,"Hexavalent chromium (Cr[VI]) is an industrial waste product known to cause nasal and lung cancer in exposed workers. Intracellularly, Cr[VI] undergoes a series of enzymatic reductions resulting in the formation of reactive chromate intermediates and oxygen free radicals. These metabolites react with DNA to cause numerous types of genomic lesions, but the cellular response to these genotoxic insults is poorly understood. Recently, we demonstrated that in response to DNA damage induced by Cr[VI], an ataxia-telangiectasia mutated (ATM) and structural maintenance of chromosomal protein 1 (SMC1)-dependent S-phase checkpoint is activated. Interestingly, this checkpoint response was only ATM-dependent in cells exposed to low doses of Cr[VI], we demonstrate that the ATM and Rad3 related kinase, ATR, is required to activate the S-phase checkpoint. In response to all doses of Cr[VI], ATR is activated and phosphorylates SMC1 to facilitate the checkpoint. Further, chromatin binding ability of Rad17 is required for this process. Taken together, these results indicate that the Rad17-ATR-SMC1 pathway is essential for Cr[VI]-induced S-phase checkpoint activation.","ATR regulates hexavalent chromium-induced S-phase checkpoint through phosphorylation of SMC1 Abs: Hexavalent chromium (Cr[VI]) is an industrial waste product known to cause nasal and lung cancer in exposed workers. Intracellularly, Cr[VI] undergoes a series of enzymatic reductions resulting in the formation of reactive chromate intermediates and oxygen free radicals. These metabolites react with DNA to cause numerous types of genomic lesions, but the cellular response to these genotoxic insults is poorly understood. Recently, we demonstrated that in response to DNA damage induced by Cr[VI], an ataxia-telangiectasia mutated (ATM) and structural maintenance of chromosomal protein 1 (SMC1)-dependent S-phase checkpoint is activated. Interestingly, this checkpoint response was only ATM-dependent in cells exposed to low doses of Cr[VI], we demonstrate that the ATM and Rad3 related kinase, ATR, is required to activate the S-phase checkpoint. In response to all doses of Cr[VI], ATR is activated and phosphorylates SMC1 to facilitate the checkpoint. Further, chromatin binding ability of Rad17 is required for this process. Taken together, these results indicate that the Rad17-ATR-SMC1 pathway is essential for Cr[VI]-induced S-phase checkpoint activation."
1231807,Rudolf and  Cervinka 2006,"The role of intracellular zinc in chromium(VI)-induced oxidative stress, DNA damage and apoptosis","Several studies have demonstrated that zinc is required for the optimal functioning of the skin. Changes in intracellular zinc concentrations have been associated with both improved protection of skin cells against various noxious factors as well as with increased susceptibility to external stress. Still, little is known about the role of intracellular zinc in hexavalent chromium (Cr(VI))-induced skin injury. To address this question, the effects of zinc deficiency or supplementation on Cr(VI)-induced cytotoxicity, oxidative stress, DNA injury and cell death were investigated in human diploid dermal fibroblasts during 48 h. Zinc levels in fibroblasts were manipulated by pretreatment of cells with 100 microM ZnSO4 and 4 or 25 microM zinc chelator TPEN. Cr(VI) (50, 10 and 1 microM) was found to produce time- and dose-dependent cytotoxicity resulting in oxidative stress, suppression of antioxidant systems and activation of p53-dependent apoptosis which is reported for the first time in this model in relation to environmental Cr(VI). Increased intracellular zinc partially attenuated Cr(VI)-induced cytotoxicity, oxidative stress and apoptosis by enhancing cellular antioxidant systems while inhibiting Cr(VI)-dependent apoptosis by preventing the activation of caspase-3. Decreased intracellular zinc enhanced cytotoxic effects of all the tested Cr(VI) concentrations, leading to rapid loss of cell membrane integrity and nuclear dispersion--hallmarks of necrosis. These new findings suggest that Cr(VI) as a model environmental toxin may damage in deeper regions residing skin fibroblasts whose susceptibility to such toxin depends among others on their intracellular Zn levels. Further investigation of the impact of Zn status on skin cells as well as any other cell populations exposed to Cr(VI) or other heavy metals is warranted.","The role of intracellular zinc in chromium(VI)-induced oxidative stress, DNA damage and apoptosis Abs: Several studies have demonstrated that zinc is required for the optimal functioning of the skin. Changes in intracellular zinc concentrations have been associated with both improved protection of skin cells against various noxious factors as well as with increased susceptibility to external stress. Still, little is known about the role of intracellular zinc in hexavalent chromium (Cr(VI))-induced skin injury. To address this question, the effects of zinc deficiency or supplementation on Cr(VI)-induced cytotoxicity, oxidative stress, DNA injury and cell death were investigated in human diploid dermal fibroblasts during 48 h. Zinc levels in fibroblasts were manipulated by pretreatment of cells with 100 microM ZnSO4 and 4 or 25 microM zinc chelator TPEN. Cr(VI) (50, 10 and 1 microM) was found to produce time- and dose-dependent cytotoxicity resulting in oxidative stress, suppression of antioxidant systems and activation of p53-dependent apoptosis which is reported for the first time in this model in relation to environmental Cr(VI). Increased intracellular zinc partially attenuated Cr(VI)-induced cytotoxicity, oxidative stress and apoptosis by enhancing cellular antioxidant systems while inhibiting Cr(VI)-dependent apoptosis by preventing the activation of caspase-3. Decreased intracellular zinc enhanced cytotoxic effects of all the tested Cr(VI) concentrations, leading to rapid loss of cell membrane integrity and nuclear dispersion--hallmarks of necrosis. These new findings suggest that Cr(VI) as a model environmental toxin may damage in deeper regions residing skin fibroblasts whose susceptibility to such toxin depends among others on their intracellular Zn levels. Further investigation of the impact of Zn status on skin cells as well as any other cell populations exposed to Cr(VI) or other heavy metals is warranted."
1231806,O'Brien et al. 2006,Incision of trivalent chromium [Cr(III)]-induced DNA damage by Bacillus caldotenax UvrABC endonuclease,"Some hexavalent chromium [Cr(VI)]-containing compounds are lung carcinogens. Once within cells, Cr(VI) is reduced to trivalent chromium [Cr(III)] which displays an affinity for both DNA bases and the phosphate backbone. A diverse array of genetic lesions is produced by Cr including Cr-DNA monoadducts, DNA interstrand crosslinks (ICLs), DNA-Cr-protein crosslinks (DPCs), abasic sites, DNA strand breaks and oxidized bases. Despite the large amount of information available on the genotoxicity of Cr, little is known regarding the molecular mechanisms involved in the removal of these lesions from damaged DNA. Recent work indicates that nucleotide excision repair (NER) is involved in the processing of Cr-DNA adducts in human and rodent cells. In order to better understand this process at the molecular level and begin to identify the Cr-DNA adducts processed by NER, the incision of CrCl(3) [Cr(III)]-damaged plasmid DNA was studied using a thermal-resistant UvrABC NER endonuclease from Bacillus caldotenax (Bca). Treatment of plasmid DNA with Cr(III) (as CrCl(3)) increased DNA binding as a function of dose. For example, at a Cr(III) concentration of 1 microM we observed approximately 2 Cr(III)-DNA adducts per plasmid. At this same concentration of Cr(III) we found that approximately 17% of the plasmid DNA contained ICLs ( approximately 0.2 ICLs/plasmid). When plasmid DNA treated with Cr(III) (1 microM) was incubated with Bca UvrABC we observed approximately 0.8 incisions/plasmid. The formation of endonuclease IV-sensitive abasic lesions or Fpg-sensitive oxidized DNA bases was not detected suggesting that the incision of Cr(III)-damaged plasmid DNA by UvrABC was not related to the generation of oxidized DNA damage. Taken together, our data suggest that a sub-fraction of Cr(III)-DNA adducts is recognized and processed by the prokaryotic NER machinery and that ICLs are not necessarily the sole lesions generated by Cr(III) that are substrates for NER.","Incision of trivalent chromium [Cr(III)]-induced DNA damage by Bacillus caldotenax UvrABC endonuclease Abs: Some hexavalent chromium [Cr(VI)]-containing compounds are lung carcinogens. Once within cells, Cr(VI) is reduced to trivalent chromium [Cr(III)] which displays an affinity for both DNA bases and the phosphate backbone. A diverse array of genetic lesions is produced by Cr including Cr-DNA monoadducts, DNA interstrand crosslinks (ICLs), DNA-Cr-protein crosslinks (DPCs), abasic sites, DNA strand breaks and oxidized bases. Despite the large amount of information available on the genotoxicity of Cr, little is known regarding the molecular mechanisms involved in the removal of these lesions from damaged DNA. Recent work indicates that nucleotide excision repair (NER) is involved in the processing of Cr-DNA adducts in human and rodent cells. In order to better understand this process at the molecular level and begin to identify the Cr-DNA adducts processed by NER, the incision of CrCl(3) [Cr(III)]-damaged plasmid DNA was studied using a thermal-resistant UvrABC NER endonuclease from Bacillus caldotenax (Bca). Treatment of plasmid DNA with Cr(III) (as CrCl(3)) increased DNA binding as a function of dose. For example, at a Cr(III) concentration of 1 microM we observed approximately 2 Cr(III)-DNA adducts per plasmid. At this same concentration of Cr(III) we found that approximately 17% of the plasmid DNA contained ICLs ( approximately 0.2 ICLs/plasmid). When plasmid DNA treated with Cr(III) (1 microM) was incubated with Bca UvrABC we observed approximately 0.8 incisions/plasmid. The formation of endonuclease IV-sensitive abasic lesions or Fpg-sensitive oxidized DNA bases was not detected suggesting that the incision of Cr(III)-damaged plasmid DNA by UvrABC was not related to the generation of oxidized DNA damage. Taken together, our data suggest that a sub-fraction of Cr(III)-DNA adducts is recognized and processed by the prokaryotic NER machinery and that ICLs are not necessarily the sole lesions generated by Cr(III) that are substrates for NER."
1231805,Vilcheck et al. 2006,FANCD2 monoubiquitination and activation by hexavalent chromium [Cr(VI)] exposure: activation is not required for repair of Cr(VI)-induced DSBs,"Fanconi anemia (FA) is a rare autosomal recessive disorder characterized by congenital abnormalities, progressive bone marrow failure, and cancer susceptibility. FA cells are hypersensitive to DNA crosslinking agents. FA is a genetically heterogeneous disease with at least 11 complementation groups. The eight cloned FA proteins interact in a common pathway with established DNA-damage-response proteins, including BRCA1 and ATM. Six FA proteins (A, C, E, F, G, and L) regulate the monoubiquitination of FANCD2 after DNA damage by crosslinking agents, which targets FANCD2 to BRCA1 nuclear foci containing BRCA2 (FANCD1) and RAD51. Some forms of hexavalent chromium [Cr(VI)] are implicated as respiratory carcinogens and induce several types of DNA lesions, including DNA interstrand crosslinks. We have shown that FA-A fibroblasts are hypersensitive to both Cr(VI)-induced apoptosis and clonogenic lethality. Here we show that Cr(VI) treatment induced monoubiquitination of FANCD2 in normal human fibroblasts, providing the first molecular evidence of Cr(VI)-induced activation of the FA pathway. FA-A fibroblasts demonstrated no FANCD2 monoubiquitination, in keeping with the requirement of FA-A for this modification. We also found that Cr(VI) treatment induced significantly more S-phase-dependent DNA double strand breaks (DSBs), as measured by gamma-H2AX expression, in FA-A fibroblasts compared to normal cells. However, and notably, DSBs were repaired equally in both normal and FA-A fibroblasts during recovery from Cr(VI) treatment. While previous research on FA has defined the genetic causes of this disease, it is critical in terms of individual risk assessment to address how cells from FA patients respond to genotoxic insult.","FANCD2 monoubiquitination and activation by hexavalent chromium [Cr(VI)] exposure: activation is not required for repair of Cr(VI)-induced DSBs Abs: Fanconi anemia (FA) is a rare autosomal recessive disorder characterized by congenital abnormalities, progressive bone marrow failure, and cancer susceptibility. FA cells are hypersensitive to DNA crosslinking agents. FA is a genetically heterogeneous disease with at least 11 complementation groups. The eight cloned FA proteins interact in a common pathway with established DNA-damage-response proteins, including BRCA1 and ATM. Six FA proteins (A, C, E, F, G, and L) regulate the monoubiquitination of FANCD2 after DNA damage by crosslinking agents, which targets FANCD2 to BRCA1 nuclear foci containing BRCA2 (FANCD1) and RAD51. Some forms of hexavalent chromium [Cr(VI)] are implicated as respiratory carcinogens and induce several types of DNA lesions, including DNA interstrand crosslinks. We have shown that FA-A fibroblasts are hypersensitive to both Cr(VI)-induced apoptosis and clonogenic lethality. Here we show that Cr(VI) treatment induced monoubiquitination of FANCD2 in normal human fibroblasts, providing the first molecular evidence of Cr(VI)-induced activation of the FA pathway. FA-A fibroblasts demonstrated no FANCD2 monoubiquitination, in keeping with the requirement of FA-A for this modification. We also found that Cr(VI) treatment induced significantly more S-phase-dependent DNA double strand breaks (DSBs), as measured by gamma-H2AX expression, in FA-A fibroblasts compared to normal cells. However, and notably, DSBs were repaired equally in both normal and FA-A fibroblasts during recovery from Cr(VI) treatment. While previous research on FA has defined the genetic causes of this disease, it is critical in terms of individual risk assessment to address how cells from FA patients respond to genotoxic insult."
1231804,Mohan and  Pittman 2006,Activated carbons and low cost adsorbents for remediation of tri- and hexavalent chromium from water,"Hexavalent chromium is a well-known highly toxic metal, considered a priority pollutant. Industrial sources of Cr(VI) include leather tanning, cooling tower blowdown, plating, electroplating, anodizing baths, rinse waters, etc. The most common method applied for chromate control is reduction of Cr(VI) to its trivalent form in acid (pH approximately 2.0) and subsequent hydroxide precipitation of Cr(III) by increasing the pH to approximately 9.0-10.0 using lime. Existing overviews of chromium removal only cover selected technologies that have traditionally been used in chromium removal. Far less attention has been paid to adsorption. Herein, we provide the first review article that provides readers an overview of the sorption capacities of commercial developed carbons and other low cost sorbents for chromium remediation. After an overview of chromium contamination is provided, more than 300 papers on chromium remediation using adsorption are discussed to provide recent information about the most widely used adsorbents applied for chromium remediation. Efforts to establish the adsorption mechanisms of Cr(III) and Cr(VI) on various adsorbents are reviewed. Chromium's impact environmental quality, sources of chromium pollution and toxicological/health effects is also briefly introduced. Interpretations of the surface interactions are offered. Particular attention is paid to comparing the sorption efficiency and capacities of commercially available activated carbons to other low cost alternatives, including an extensive table.","Activated carbons and low cost adsorbents for remediation of tri- and hexavalent chromium from water Abs: Hexavalent chromium is a well-known highly toxic metal, considered a priority pollutant. Industrial sources of Cr(VI) include leather tanning, cooling tower blowdown, plating, electroplating, anodizing baths, rinse waters, etc. The most common method applied for chromate control is reduction of Cr(VI) to its trivalent form in acid (pH approximately 2.0) and subsequent hydroxide precipitation of Cr(III) by increasing the pH to approximately 9.0-10.0 using lime. Existing overviews of chromium removal only cover selected technologies that have traditionally been used in chromium removal. Far less attention has been paid to adsorption. Herein, we provide the first review article that provides readers an overview of the sorption capacities of commercial developed carbons and other low cost sorbents for chromium remediation. After an overview of chromium contamination is provided, more than 300 papers on chromium remediation using adsorption are discussed to provide recent information about the most widely used adsorbents applied for chromium remediation. Efforts to establish the adsorption mechanisms of Cr(III) and Cr(VI) on various adsorbents are reviewed. Chromium's impact environmental quality, sources of chromium pollution and toxicological/health effects is also briefly introduced. Interpretations of the surface interactions are offered. Particular attention is paid to comparing the sorption efficiency and capacities of commercially available activated carbons to other low cost alternatives, including an extensive table."
1231802,Suksabye et al. 2007,Chromium removal from electroplating wastewater by coir pith,"Coir pith is a by-product from padding used in mattress factories. It contains a high amount of lignin. Therefore, this study investigated the use of coir pith in the removal of hexavalent chromium from electroplating wastewater by varying the parameters, such as the system pH, contact time, adsorbent dosage, and temperature. The maximum removal (99.99%) was obtained at 2% (w/v) dosage, particle size &lt;75microm, at initial Cr(VI) 1647mgl(-1), system pH 2, and an equilibrium time of 18h. The adsorption isotherm of coir pith fitted reasonably well with the Langmuir model. The maximum Cr(VI) adsorption capacity of coir pith at 15, 30, 45 and 60 degrees C was 138.04, 197.23, 262.89 and 317.65mgCr(VI)g(-1) coir pith, respectively. Thermodynamic parameters indicated an endothermic process and the adsorption process was favored at high temperature. Desorption studies of Cr(VI) on coir pith and X-ray absorption near edge structure (XANES) suggested that most of the chromium bound on the coir pith was in Cr(III) form due to the fact that the toxic Cr(VI) adsorbed on the coir pith by electrostatic attraction was easily reduced to less toxic Cr(III). Fourier transform infrared (FT-IR) spectrometry analysis indicated that the carbonyl (CO) groups and methoxy (O-CH(3)) groups from the lignin structure in coir pith may be involved in the mechanism of chromium adsorption. The reduced Cr(III) on the coir pith surface may be bound with CO groups and O-CH(3) groups through coordinate covalent bonding in which a lone pair of electrons in the oxygen atoms of the methoxy and carbonyl groups can be donated to form a shared bond with Cr(III).","Chromium removal from electroplating wastewater by coir pith Abs: Coir pith is a by-product from padding used in mattress factories. It contains a high amount of lignin. Therefore, this study investigated the use of coir pith in the removal of hexavalent chromium from electroplating wastewater by varying the parameters, such as the system pH, contact time, adsorbent dosage, and temperature. The maximum removal (99.99%) was obtained at 2% (w/v) dosage, particle size &lt;75microm, at initial Cr(VI) 1647mgl(-1), system pH 2, and an equilibrium time of 18h. The adsorption isotherm of coir pith fitted reasonably well with the Langmuir model. The maximum Cr(VI) adsorption capacity of coir pith at 15, 30, 45 and 60 degrees C was 138.04, 197.23, 262.89 and 317.65mgCr(VI)g(-1) coir pith, respectively. Thermodynamic parameters indicated an endothermic process and the adsorption process was favored at high temperature. Desorption studies of Cr(VI) on coir pith and X-ray absorption near edge structure (XANES) suggested that most of the chromium bound on the coir pith was in Cr(III) form due to the fact that the toxic Cr(VI) adsorbed on the coir pith by electrostatic attraction was easily reduced to less toxic Cr(III). Fourier transform infrared (FT-IR) spectrometry analysis indicated that the carbonyl (CO) groups and methoxy (O-CH(3)) groups from the lignin structure in coir pith may be involved in the mechanism of chromium adsorption. The reduced Cr(III) on the coir pith surface may be bound with CO groups and O-CH(3) groups through coordinate covalent bonding in which a lone pair of electrons in the oxygen atoms of the methoxy and carbonyl groups can be donated to form a shared bond with Cr(III)."
1231801,Wei et al. 2006,Studies and application of catalytic kinetic spectrophotometric determination of trace chromium(VI) sensitized by microemulsion medium,A new catalytic kinetic spectrophotometric method for the determination of trace amount of chromium (VI) in microemulsion medium has been developed. The method is based on the catalytic effect of chromium (VI) on the oxidation of nuclear fast red in the presence of Tween-80 microemulsion and HAc-NaAc buffer solution (pH = 5.2). The linear ranges are in the range of 0 approximately 0.0480 microg mL(-1) of Cr (VI) at 528 nm and the detection limit is 1.56x10(-9)g mL(-1). The method has been applied in determination of Cr (VI) in water and food samples with satisfactory results. The relative standard deviation is less than 4.6 % and the recovery is 93.5 approximately 104 %.,Studies and application of catalytic kinetic spectrophotometric determination of trace chromium(VI) sensitized by microemulsion medium Abs: A new catalytic kinetic spectrophotometric method for the determination of trace amount of chromium (VI) in microemulsion medium has been developed. The method is based on the catalytic effect of chromium (VI) on the oxidation of nuclear fast red in the presence of Tween-80 microemulsion and HAc-NaAc buffer solution (pH = 5.2). The linear ranges are in the range of 0 approximately 0.0480 microg mL(-1) of Cr (VI) at 528 nm and the detection limit is 1.56x10(-9)g mL(-1). The method has been applied in determination of Cr (VI) in water and food samples with satisfactory results. The relative standard deviation is less than 4.6 % and the recovery is 93.5 approximately 104 %.
1231800,Aruldhas et al. 2006,"In vivo spermatotoxic effect of chromium as reflected in the epididymal epithelial principal cells, basal cells, and intraepithelial macrophages of a nonhuman primate (Macaca radiata Geoffroy)","<strong>OBJECTIVE: </strong>To understand, through a simulation experiment in a nonhuman primate model, the potential in vivo spermatotoxic toxic effect of hexavalent chromium (CrVI) in men who are occupationally or environmentally exposed to it.<br /><br /><strong>DESIGN: </strong>Controlled laboratory study.<br /><br /><strong>SETTING: </strong>Research laboratory in a department of endocrinology in a university in India.<br /><br /><strong>ANIMAL(S): </strong>Male bonnet monkey, Macaca radiata Geoffroy.<br /><br /><strong>INTERVENTION(S): </strong>Monkeys were exposed ad libitum to 100, 200, and 400 ppm CrVI, dissolved in drinking water, for a chronic period of 180 days.<br /><br /><strong>MAIN OUTCOME MEASURE(S): </strong>Examination of epididymis with a transmission electron microscope and assessment of the effect of CrVI in terms of accumulation of sperm-derived lipofuscin (LF) material in the principal cells, basal cells, and intraepithelial macrophages of the epithelium.<br /><br /><strong>RESULT(S): </strong>The abundance of basal cells and intraepithelial macrophages and the content of LF material in these cell types increased. The principal cells phagocytosed from the lumen the dead sperm resulting from CrVI exposure and processed them partially into LF material, which was acquired by the basal cells and intraepithelial macrophages and processed further. The LF material-laden basal cells and intraepithelial macrophages appeared to leave the epithelium, accompanied by recruitment of fresh basal cells and intraepithelial macrophages.<br /><br /><strong>CONCLUSION(S): </strong>Occupational or environmental exposure to CrVI, as would occur in the tannery, soap, and other industries in developing and underdeveloped countries, can be toxic in vivo to spermatozoa.","In vivo spermatotoxic effect of chromium as reflected in the epididymal epithelial principal cells, basal cells, and intraepithelial macrophages of a nonhuman primate (Macaca radiata Geoffroy) Abs: <strong>OBJECTIVE: </strong>To understand, through a simulation experiment in a nonhuman primate model, the potential in vivo spermatotoxic toxic effect of hexavalent chromium (CrVI) in men who are occupationally or environmentally exposed to it.<br /><br /><strong>DESIGN: </strong>Controlled laboratory study.<br /><br /><strong>SETTING: </strong>Research laboratory in a department of endocrinology in a university in India.<br /><br /><strong>ANIMAL(S): </strong>Male bonnet monkey, Macaca radiata Geoffroy.<br /><br /><strong>INTERVENTION(S): </strong>Monkeys were exposed ad libitum to 100, 200, and 400 ppm CrVI, dissolved in drinking water, for a chronic period of 180 days.<br /><br /><strong>MAIN OUTCOME MEASURE(S): </strong>Examination of epididymis with a transmission electron microscope and assessment of the effect of CrVI in terms of accumulation of sperm-derived lipofuscin (LF) material in the principal cells, basal cells, and intraepithelial macrophages of the epithelium.<br /><br /><strong>RESULT(S): </strong>The abundance of basal cells and intraepithelial macrophages and the content of LF material in these cell types increased. The principal cells phagocytosed from the lumen the dead sperm resulting from CrVI exposure and processed them partially into LF material, which was acquired by the basal cells and intraepithelial macrophages and processed further. The LF material-laden basal cells and intraepithelial macrophages appeared to leave the epithelium, accompanied by recruitment of fresh basal cells and intraepithelial macrophages.<br /><br /><strong>CONCLUSION(S): </strong>Occupational or environmental exposure to CrVI, as would occur in the tannery, soap, and other industries in developing and underdeveloped countries, can be toxic in vivo to spermatozoa."
1231798,Codd et al. 2006,Chromium(V) complexes generated in Arthrobacter oxydans by simulation analysis of EPR spectra,"Chromium(V) is an intermediate formed during the reduction of Cr(VI) to Cr(III) compounds by various bacteria. However, little is known about the nature, localization and reactivity of Cr(V) species in microbial systems. Electron paramagnetic resonance (EPR) spectroscopy was used to study the nature of Cr(V) complexes generated in basalt-inhabiting Gram-positive Arthrobacter oxydans bacteria after exposure to high concentrations of Cr(VI). Numerical simulations of the EPR spectroscopic data provide strong evidence for at least two different diolato-type oxoCr(V) complexes (I, g(iso)=1.9801; II, g(iso)=1.9796) involving bacterial cell wall macromolecules in the Cr(VI)-A. oxydans system. The relative concentrations of the two oxoCr(V)-diolato species differ when Cr(VI) is incubated with either untreated A. oxydans cells (I:II approximately 50:50) or lyophilized cells (I:II approximately 10:90). Based upon the magnitudes of the proton superhyperfine coupling constants ((1)H a(iso)) for species I and II, the EPR simulation model is unable to distinguish unambiguously whether the oxoCr(V)-diolato species are linear alkoxides or cyclic diols (carbohydrates). The oxygen-containing functional groups associated with teichoic acids are the most likely candidates for complexation with the Cr(V) ion.","Chromium(V) complexes generated in Arthrobacter oxydans by simulation analysis of EPR spectra Abs: Chromium(V) is an intermediate formed during the reduction of Cr(VI) to Cr(III) compounds by various bacteria. However, little is known about the nature, localization and reactivity of Cr(V) species in microbial systems. Electron paramagnetic resonance (EPR) spectroscopy was used to study the nature of Cr(V) complexes generated in basalt-inhabiting Gram-positive Arthrobacter oxydans bacteria after exposure to high concentrations of Cr(VI). Numerical simulations of the EPR spectroscopic data provide strong evidence for at least two different diolato-type oxoCr(V) complexes (I, g(iso)=1.9801; II, g(iso)=1.9796) involving bacterial cell wall macromolecules in the Cr(VI)-A. oxydans system. The relative concentrations of the two oxoCr(V)-diolato species differ when Cr(VI) is incubated with either untreated A. oxydans cells (I:II approximately 50:50) or lyophilized cells (I:II approximately 10:90). Based upon the magnitudes of the proton superhyperfine coupling constants ((1)H a(iso)) for species I and II, the EPR simulation model is unable to distinguish unambiguously whether the oxoCr(V)-diolato species are linear alkoxides or cyclic diols (carbohydrates). The oxygen-containing functional groups associated with teichoic acids are the most likely candidates for complexation with the Cr(V) ion."
1231797,Wang et al. 2006,"Oral administration of Cr(VI) induced oxidative stress, DNA damage and apoptotic cell death in mice","Potassium dichromate (Cr(VI)) was given orally to Swiss mice for 1 and 5 days with the dose of 25, 50 and 100 mg/kg body weight per day, respectively. Oxidative stress including the level of reactive oxygen species (ROS), the extent of lipid peroxidation and the activity of antioxidant enzymes in liver and kidney was determined. DNA damage in peripheral blood lymphocytes was determined by single-cell gel electrophoresis (comet assay). Apoptotic cell death in liver was detected using transmission electron microscopy and TUNEL assay. The results indicated that administration of Cr(VI) had caused a significant increase of ROS level in liver both after 1 and 5 days of exposure, accompanied with a dose-dependent decrease in superoxide dismutase (SOD) and catalase (CAT) activities. The malondialdehyde (MDA) content in liver was not changed as compared to the control animals. In contrast to the liver, no significant changes were observed in kidney on ROS, SOD, CAT and MDA as compared to the control animals. Dose- and time-dependent effects were observed on DNA damage after 1 and 5 days treatment. Significant difference was observed on the number of TUNEL positive liver cells between the control and Cr(VI) treatment groups. The apoptotic cells were also identified by characteristic ultrastructural features. The results obtained from the present study showed that Cr(VI) given orally to mice could induce dose- and time-dependent effects on DNA damage, hepatic oxidative stress and hepatocytes apoptosis. No significant oxidative stress observed in kidney in the study may suggest that the way of Cr(VI) exposure is an important factor affecting its toxicity.","Oral administration of Cr(VI) induced oxidative stress, DNA damage and apoptotic cell death in mice Abs: Potassium dichromate (Cr(VI)) was given orally to Swiss mice for 1 and 5 days with the dose of 25, 50 and 100 mg/kg body weight per day, respectively. Oxidative stress including the level of reactive oxygen species (ROS), the extent of lipid peroxidation and the activity of antioxidant enzymes in liver and kidney was determined. DNA damage in peripheral blood lymphocytes was determined by single-cell gel electrophoresis (comet assay). Apoptotic cell death in liver was detected using transmission electron microscopy and TUNEL assay. The results indicated that administration of Cr(VI) had caused a significant increase of ROS level in liver both after 1 and 5 days of exposure, accompanied with a dose-dependent decrease in superoxide dismutase (SOD) and catalase (CAT) activities. The malondialdehyde (MDA) content in liver was not changed as compared to the control animals. In contrast to the liver, no significant changes were observed in kidney on ROS, SOD, CAT and MDA as compared to the control animals. Dose- and time-dependent effects were observed on DNA damage after 1 and 5 days treatment. Significant difference was observed on the number of TUNEL positive liver cells between the control and Cr(VI) treatment groups. The apoptotic cells were also identified by characteristic ultrastructural features. The results obtained from the present study showed that Cr(VI) given orally to mice could induce dose- and time-dependent effects on DNA damage, hepatic oxidative stress and hepatocytes apoptosis. No significant oxidative stress observed in kidney in the study may suggest that the way of Cr(VI) exposure is an important factor affecting its toxicity."
1231794,Mutti and  Corradi 2006,Recent developments in human biomonitoring: non-invasive assessment of target tissue dose and effects of pneumotoxic metals,"Tobacco smoke and polluted environments substantially increase the lung burden of pneumotoxic chemicals, particularly pneumotoxic metallic elements. To achieve a better understanding of the early events between exposure to inhaled toxicants and the onset of adverse effects on the lung, the characterization of dose at the target organ would be extremely useful. Exhaled breath condensate (EBC), obtained by cooling exhaled air under conditions of spontaneous breathing, is a novel technique that could provide a non-invasive assessment of pulmonary pathobiology. Considering that EBC is water practically free of interfering solutes, it represents an ideal biological matrix for elemental characterization. Published data show that several toxic metals and trace elements are detectable in EBC, raising the possibility of using this medium to quantify the lung tissue dose of pneumotoxic substances. This novel approach may represent a significant advance over the analysis of alternative media (blood, serum, urine, hair), which are not as reliable (owing to interfering substances in the complex matrix) and reflect systemic rather than lung (target tissue) levels of both toxic metals and essential trace elements. Data obtained among workers occupationally exposed to either hard metals or chromium (VI) and in smokers with or without chronic obstructive pulmonary disease (COPD) are reviewed to show that--together with biomarkers of exposure--EBC also allows the simultaneous quantification of biomarkers of effect directly sampled from the epithelial lining fluid, thus providing novel insights on both kinetic and dynamic aspects of metal toxicology.","Recent developments in human biomonitoring: non-invasive assessment of target tissue dose and effects of pneumotoxic metals Abs: Tobacco smoke and polluted environments substantially increase the lung burden of pneumotoxic chemicals, particularly pneumotoxic metallic elements. To achieve a better understanding of the early events between exposure to inhaled toxicants and the onset of adverse effects on the lung, the characterization of dose at the target organ would be extremely useful. Exhaled breath condensate (EBC), obtained by cooling exhaled air under conditions of spontaneous breathing, is a novel technique that could provide a non-invasive assessment of pulmonary pathobiology. Considering that EBC is water practically free of interfering solutes, it represents an ideal biological matrix for elemental characterization. Published data show that several toxic metals and trace elements are detectable in EBC, raising the possibility of using this medium to quantify the lung tissue dose of pneumotoxic substances. This novel approach may represent a significant advance over the analysis of alternative media (blood, serum, urine, hair), which are not as reliable (owing to interfering substances in the complex matrix) and reflect systemic rather than lung (target tissue) levels of both toxic metals and essential trace elements. Data obtained among workers occupationally exposed to either hard metals or chromium (VI) and in smokers with or without chronic obstructive pulmonary disease (COPD) are reviewed to show that--together with biomarkers of exposure--EBC also allows the simultaneous quantification of biomarkers of effect directly sampled from the epithelial lining fluid, thus providing novel insights on both kinetic and dynamic aspects of metal toxicology."
1231793,Kumar et al. 2007,Hexavalent chromium removal from wastewater using aniline formaldehyde condensate coated silica gel,"A resinous polymer, aniline formaldehyde condensate (AFC) coated on silica gel was used as an adsorbent in batch system for removal of hexavalent chromium from aqueous solution by considering the effects of various parameters like reaction pH, dose of AFC coated silica gel, initial Cr(VI) concentration and aniline to formaldehyde ratio in AFC synthesis. The optimum pH for total chromium [Cr(VI) and Cr(III)] adsorption was observed as 3. Total chromium adsorption was second order and equilibrium was achieved within 90-120 min. Aniline to formaldehyde ratio of 1.6:1 during AFC synthesis was ideal for chromium removal. Total chromium adsorption followed Freundlich's isotherm with adsorption capacity of 65 mg/g at initial Cr(VI) 200mg/L. Total chromium removal was explained as combinations of electrostatic attraction of acid chromate ion by protonated AFC, reduction of Cr(VI) to Cr(III) and bond formation of Cr(III) with nitrogen atom of AFC. Almost 40-84% of adsorbed chromium was recovered during desorption by NaOH, EDTA and mineral acids. AFC coated silica gel can be effectively used for treatment of chromium containing wastewaters as an alternative.","Hexavalent chromium removal from wastewater using aniline formaldehyde condensate coated silica gel Abs: A resinous polymer, aniline formaldehyde condensate (AFC) coated on silica gel was used as an adsorbent in batch system for removal of hexavalent chromium from aqueous solution by considering the effects of various parameters like reaction pH, dose of AFC coated silica gel, initial Cr(VI) concentration and aniline to formaldehyde ratio in AFC synthesis. The optimum pH for total chromium [Cr(VI) and Cr(III)] adsorption was observed as 3. Total chromium adsorption was second order and equilibrium was achieved within 90-120 min. Aniline to formaldehyde ratio of 1.6:1 during AFC synthesis was ideal for chromium removal. Total chromium adsorption followed Freundlich's isotherm with adsorption capacity of 65 mg/g at initial Cr(VI) 200mg/L. Total chromium removal was explained as combinations of electrostatic attraction of acid chromate ion by protonated AFC, reduction of Cr(VI) to Cr(III) and bond formation of Cr(III) with nitrogen atom of AFC. Almost 40-84% of adsorbed chromium was recovered during desorption by NaOH, EDTA and mineral acids. AFC coated silica gel can be effectively used for treatment of chromium containing wastewaters as an alternative."
1231792,Michaels et al. 2006,"Lung cancer mortality in the German chromate industry, 1958 to 1998",,"Lung cancer mortality in the German chromate industry, 1958 to 1998 Abs: "
1231790,Tessier and  Pascal 2006,"Activation of MAP kinases by hexavalent chromium, manganese and nickel in human lung epithelial cells","Epidemiological studies indicate that workers who perform welding operations are at increased risk for bronchitis, siderosis, occupational asthma and lung cancer due to fume exposure. Welding fumes are a complex chemical mixture, and the metal composition is hypothesized to be an etiological factor in respiratory disease due to this exposure. In the present study, human lung epithelial cells in vitro responded to hexavalent chromium, manganese and nickel over a concentration range of 0.2-200 microM with a significant increase in intracellular phosphoprotein (a measure of stress response pathway activation). The mitogen-activated protein kinases ERK1/2, SAPK/JNK and p38 were activated via phosphorylation following 1-h exposures. Hexavalent chromium up-regulated p-38 phosphorylation 23-fold and SAPK/JNK phosphorylation 17-fold, with a comparatively modest 4-fold increase in ERK1/2 phosphorylation. Manganese caused a two- to four-fold increase in SAPK/JNK and ERK 1/2 phosphorylation, with no observed effects on p38 kinase. Nickel caused increased (two-fold) phosphorylation of ERK 1/2 only, and was not cytotoxic over the tested concentration range. The observed effects of welding fume metals on cellular signaling in lung epithelium demonstrate a potentially significant interplay between stress-response signaling (p38 and SAPK/JNK) and anti-apototic signaling (ERK 1/2) that is dependant on the specific metal or combination of metals involved.","Activation of MAP kinases by hexavalent chromium, manganese and nickel in human lung epithelial cells Abs: Epidemiological studies indicate that workers who perform welding operations are at increased risk for bronchitis, siderosis, occupational asthma and lung cancer due to fume exposure. Welding fumes are a complex chemical mixture, and the metal composition is hypothesized to be an etiological factor in respiratory disease due to this exposure. In the present study, human lung epithelial cells in vitro responded to hexavalent chromium, manganese and nickel over a concentration range of 0.2-200 microM with a significant increase in intracellular phosphoprotein (a measure of stress response pathway activation). The mitogen-activated protein kinases ERK1/2, SAPK/JNK and p38 were activated via phosphorylation following 1-h exposures. Hexavalent chromium up-regulated p-38 phosphorylation 23-fold and SAPK/JNK phosphorylation 17-fold, with a comparatively modest 4-fold increase in ERK1/2 phosphorylation. Manganese caused a two- to four-fold increase in SAPK/JNK and ERK 1/2 phosphorylation, with no observed effects on p38 kinase. Nickel caused increased (two-fold) phosphorylation of ERK 1/2 only, and was not cytotoxic over the tested concentration range. The observed effects of welding fume metals on cellular signaling in lung epithelium demonstrate a potentially significant interplay between stress-response signaling (p38 and SAPK/JNK) and anti-apototic signaling (ERK 1/2) that is dependant on the specific metal or combination of metals involved."
1231789,Liu et al. 2007,A TiO2/AC composite photocatalyst with high activity and easy separation prepared by a hydrothermal method,"In the present work, a TiO2/activated carbon (AC) photocatalyst with high activity and easy separation was prepared using a hydrothermal method. Phenol, methyl orange (MO) and Cr(VI) were used as target pollutants to test the activity and decantability. SEM, XRD, FTIR, diffuse reflectance spectra (UV/DRS) and N2 adsorption isotherms were used to characterize the crystalline and electronic structure. Results show that the AC composite has a significant effect on the TiO2 activity. With suitable AC content, the TiO2/xAC catalysts prepared were much more active. The TiO2/5AC catalyst exhibited easy separation and less deactivation after several runs, and was less sensitive to pH changes. UV/DRS revealed that no electronic bandgap changes in TiO2 occurred on addition of the AC. SEM and XRD results suggest that better TiO2 distribution can be achieved when an optimal AC content is used. A Ti-O-C bond was formed and a slight conjugation effect appeared between the AC bulk and TiO2. The advantages of the obtained TiO2/5AC catalyst revealed its great practical potential in wastewater treatment.","A TiO2/AC composite photocatalyst with high activity and easy separation prepared by a hydrothermal method Abs: In the present work, a TiO2/activated carbon (AC) photocatalyst with high activity and easy separation was prepared using a hydrothermal method. Phenol, methyl orange (MO) and Cr(VI) were used as target pollutants to test the activity and decantability. SEM, XRD, FTIR, diffuse reflectance spectra (UV/DRS) and N2 adsorption isotherms were used to characterize the crystalline and electronic structure. Results show that the AC composite has a significant effect on the TiO2 activity. With suitable AC content, the TiO2/xAC catalysts prepared were much more active. The TiO2/5AC catalyst exhibited easy separation and less deactivation after several runs, and was less sensitive to pH changes. UV/DRS revealed that no electronic bandgap changes in TiO2 occurred on addition of the AC. SEM and XRD results suggest that better TiO2 distribution can be achieved when an optimal AC content is used. A Ti-O-C bond was formed and a slight conjugation effect appeared between the AC bulk and TiO2. The advantages of the obtained TiO2/5AC catalyst revealed its great practical potential in wastewater treatment."
1231787,Puncochar 2006,Exposure determination and respirator selection under the OSHA Hexavalent Chromium Standards,,Exposure determination and respirator selection under the OSHA Hexavalent Chromium Standards Abs: 
1231786,Rocha et al. 2006,Influence of the drying conditions of Sargassum sp. alga on the bioadsorption of hexavalent chromium,"Industrial wastes containing synthetic organic compounds and heavy metals are among the most dangerous residues, whose growth has followed the increase in industrial activity. Heavy metals are readily assimilated into the food chain and therefore easily accumulated in the ecosystem. To remove heavy metals from aqueous solutions, marine algae may be used as adsorbents either in their natural form or after treatments by a cross-linking process to improve their mechanical resistance. Drying of biosorbents, such as marine algae, is mentioned in many previous works as a step preceding the adsorption/dessorption cycle. Concerning algae, drying of its fresh biomass allows for proper storage and enhances performance in the sorption of heavy metals. In this work, physical and morphological analyses of fresh and dried Sargassum sp. marine algae, harvested offshore São Sebastião, São Paulo state, Brazil, were performed in order to assess the influence of drying conditions on the biosorption process. Chromium concentrations were also determined in different parts of the algal structure before and after the biosorption process. The drying promoted structural changes in the algae, like shrinkage and porosity reduction. It was also observed that the chromium retention was dependent on the structural arrangement of the alga parts, in which the leaf was the major biosorbent.","Influence of the drying conditions of Sargassum sp. alga on the bioadsorption of hexavalent chromium Abs: Industrial wastes containing synthetic organic compounds and heavy metals are among the most dangerous residues, whose growth has followed the increase in industrial activity. Heavy metals are readily assimilated into the food chain and therefore easily accumulated in the ecosystem. To remove heavy metals from aqueous solutions, marine algae may be used as adsorbents either in their natural form or after treatments by a cross-linking process to improve their mechanical resistance. Drying of biosorbents, such as marine algae, is mentioned in many previous works as a step preceding the adsorption/dessorption cycle. Concerning algae, drying of its fresh biomass allows for proper storage and enhances performance in the sorption of heavy metals. In this work, physical and morphological analyses of fresh and dried Sargassum sp. marine algae, harvested offshore São Sebastião, São Paulo state, Brazil, were performed in order to assess the influence of drying conditions on the biosorption process. Chromium concentrations were also determined in different parts of the algal structure before and after the biosorption process. The drying promoted structural changes in the algae, like shrinkage and porosity reduction. It was also observed that the chromium retention was dependent on the structural arrangement of the alga parts, in which the leaf was the major biosorbent."
1231784,Aceves et al. 2007,"Effects of Cr3+, Cr6+ and tannery sludge on C and N mineralization and microbial activity in semi-arid soils","The aim of this study was to evaluate the effect of two Cr species (Cr(3+) and Cr(6+)) on N and C mineralization and dehydrogenase activity in semi-arid soils. The Cr species (250 mg kg(-1)soil) were either added alone or mixed with tannery sludge (0.0125 g g(-1)) to three soils: cultivated soils, and outside and under the canopy of mesquite trees were then incubated for 180 days at 25 degrees C. Sole Cr(6+) addition had a higher inhibition of CO(2) production rate in cultivated soil (58-73%) than in soils under the canopy and outside the canopy. Soil outside the canopy amended with Cr(6+) showed the highest inhibition of dehydrogenase activity (40-100%) followed by cultivated and under the canopy soils. However, Cr(6+) added alone increased the inhibition of nitrification in soil outside the canopy (68-84%, from 30 to 120 days), followed by under the canopy and cultivated soils. The addition of tannery sludge to Cr(6+) significantly reduce the CO(2) production rate and dehydrogenase activity in all three soils, and increased the inhibition of nitrification in the following order: outside the canopy, cultivated and under the canopy soils. The addition of Cr(3+) or Cr(3+) plus tannery sludge either stimulated or inhibited CO(2) production rate, dehydrogenate activity and ammonification in the three soils in no clearly defined order. Measurement of dehydrogenase activity was the best tool for assessing the harmful effect of Cr(6+) on soil microbial activity in semi-arid soils exposed for an extended period.","Effects of Cr3+, Cr6+ and tannery sludge on C and N mineralization and microbial activity in semi-arid soils Abs: The aim of this study was to evaluate the effect of two Cr species (Cr(3+) and Cr(6+)) on N and C mineralization and dehydrogenase activity in semi-arid soils. The Cr species (250 mg kg(-1)soil) were either added alone or mixed with tannery sludge (0.0125 g g(-1)) to three soils: cultivated soils, and outside and under the canopy of mesquite trees were then incubated for 180 days at 25 degrees C. Sole Cr(6+) addition had a higher inhibition of CO(2) production rate in cultivated soil (58-73%) than in soils under the canopy and outside the canopy. Soil outside the canopy amended with Cr(6+) showed the highest inhibition of dehydrogenase activity (40-100%) followed by cultivated and under the canopy soils. However, Cr(6+) added alone increased the inhibition of nitrification in soil outside the canopy (68-84%, from 30 to 120 days), followed by under the canopy and cultivated soils. The addition of tannery sludge to Cr(6+) significantly reduce the CO(2) production rate and dehydrogenase activity in all three soils, and increased the inhibition of nitrification in the following order: outside the canopy, cultivated and under the canopy soils. The addition of Cr(3+) or Cr(3+) plus tannery sludge either stimulated or inhibited CO(2) production rate, dehydrogenate activity and ammonification in the three soils in no clearly defined order. Measurement of dehydrogenase activity was the best tool for assessing the harmful effect of Cr(6+) on soil microbial activity in semi-arid soils exposed for an extended period."
1231783,Acevedo-Aguilar et al. 2006,"Hexavalent chromium removal in vitro and from industrial wastes, using chromate-resistant strains of filamentous fungi indigenous to contaminated wastes","Two chromate-resistant filamentous fungi, strains H13 and Ed8, were selected from seven independent fungal isolates indigenous to Cr(VI)-contaminated soil because of their ability to decrease hexavalent chromium levels in the growth medium. Morphophysiological studies identified strain H13 as a Penicillium sp. isolate and Ed8 as an Aspergillus sp. isolate. When incubated in minimal medium with glucose as a carbon source and in the presence of 50 microg/mL Cr(VI), these strains caused complete disappearance of Cr(VI) in the growth medium after about 72 h of incubation. Total chromium concentration in growth medium was constant during culture growth, and no accumulation of chromium in fungal biomass was observed. Quantitative determinations of oxidized and reduced chromium species during the reduction process revealed stoichiometric conversion of Cr(VI) to Cr(III). A decrease in Cr(VI) levels from industrial wastes was also induced by Ed8 or H13 biomass. These results indicate that chromate-resistant filamentous fungi with Cr(VI)-reducing capability could be useful for the removal of Cr(VI) contamination.","Hexavalent chromium removal in vitro and from industrial wastes, using chromate-resistant strains of filamentous fungi indigenous to contaminated wastes Abs: Two chromate-resistant filamentous fungi, strains H13 and Ed8, were selected from seven independent fungal isolates indigenous to Cr(VI)-contaminated soil because of their ability to decrease hexavalent chromium levels in the growth medium. Morphophysiological studies identified strain H13 as a Penicillium sp. isolate and Ed8 as an Aspergillus sp. isolate. When incubated in minimal medium with glucose as a carbon source and in the presence of 50 microg/mL Cr(VI), these strains caused complete disappearance of Cr(VI) in the growth medium after about 72 h of incubation. Total chromium concentration in growth medium was constant during culture growth, and no accumulation of chromium in fungal biomass was observed. Quantitative determinations of oxidized and reduced chromium species during the reduction process revealed stoichiometric conversion of Cr(VI) to Cr(III). A decrease in Cr(VI) levels from industrial wastes was also induced by Ed8 or H13 biomass. These results indicate that chromate-resistant filamentous fungi with Cr(VI)-reducing capability could be useful for the removal of Cr(VI) contamination."
1231782,Campbell et al. 2006,Magnitude and directional measures of water and Cr(VI) fluxes by passive flux meter,"A new configuration of the passive fluxmeter (PFM) is presented that provides for simultaneous measurements of both the magnitude and the direction of ambient groundwater specific discharge qo and Cr(VI) mass flux J(Cr). The PFM is configured as a cylindrical unit with an interior divided into a center section and three outer sectors, each packed with a granular anion exchange resin having high sorption capacity for the Cr(VI) oxyanions CrO4(2-) and HCrO4-. The sorbent in the center section is preloaded with benzoate as the &quot;resident&quot; tracer. Laboratory experiments were conducted in which PFMs were placed in porous packed bed columns, through which was passed a measured volume of synthetic groundwater containing Cr(VI). During the deployment period, some of the resident tracer is depleted while the Cr(VI) is sorbed. The resin was then removed from the four sectors separately and extracted to determine the &quot;captured&quot; mass of Cr(VI) and the residual mass of the resident tracer in each. Cumulative specific discharge, q0t, values were assessed using the residual mass of benzoate retained in the center section. The direction of this discharge theta was ascertained from the mass distribution of benzoate intercepted and retained in the outer three sections of the PFM. Cumulative chromium fluxes, J(Cr)t, were quantified using the total Cr(VI) mass intercepted and retained on the PFM. Experiments produced an average measurement error for direction theta of 3 degrees +/- 14 degrees, while the average measurement errors for q0 and J(Cr) were, respectively, -8% +/- 15% and -12% +/- 23%. Results demonstrate the potential utility of the new PFM configuration for characterizing groundwater and contaminant fluxes.","Magnitude and directional measures of water and Cr(VI) fluxes by passive flux meter Abs: A new configuration of the passive fluxmeter (PFM) is presented that provides for simultaneous measurements of both the magnitude and the direction of ambient groundwater specific discharge qo and Cr(VI) mass flux J(Cr). The PFM is configured as a cylindrical unit with an interior divided into a center section and three outer sectors, each packed with a granular anion exchange resin having high sorption capacity for the Cr(VI) oxyanions CrO4(2-) and HCrO4-. The sorbent in the center section is preloaded with benzoate as the &quot;resident&quot; tracer. Laboratory experiments were conducted in which PFMs were placed in porous packed bed columns, through which was passed a measured volume of synthetic groundwater containing Cr(VI). During the deployment period, some of the resident tracer is depleted while the Cr(VI) is sorbed. The resin was then removed from the four sectors separately and extracted to determine the &quot;captured&quot; mass of Cr(VI) and the residual mass of the resident tracer in each. Cumulative specific discharge, q0t, values were assessed using the residual mass of benzoate retained in the center section. The direction of this discharge theta was ascertained from the mass distribution of benzoate intercepted and retained in the outer three sections of the PFM. Cumulative chromium fluxes, J(Cr)t, were quantified using the total Cr(VI) mass intercepted and retained on the PFM. Experiments produced an average measurement error for direction theta of 3 degrees +/- 14 degrees, while the average measurement errors for q0 and J(Cr) were, respectively, -8% +/- 15% and -12% +/- 23%. Results demonstrate the potential utility of the new PFM configuration for characterizing groundwater and contaminant fluxes."
1231781,Sun et al. 2006,Characterization of primary precipitate composition formed during co-removal of Cr(VI) with Cu(II) in synthetic wastewater,"<strong>BACKGROUND, AIMS AND SCOPE: </strong>Hexavalent chromium [Cr(VI)] cannot react with either carbonate or hydroxide to form chromium precipitates. However, by using a precipitation technology to treat plating wastewater containing Cr(VI), Cu(II), Ni(II) and Zn(II), approximately 78% of Cr(VI) (initial 60 mg/L) was co-removed with the precipitation of Cu(II), Ni(II) and Zn(II) (each 150 mg/L) by dosing with Na2CO3 (Sun 2003). Direct precipitation by forming Cu(II)-Cr(VI) precipitates followed by adsorption of Cr(VI) onto freshly formed Cu-precipitates was subsequently found to be the main mechanism(s) involved in Cr(VI) co-removal with Cu(II) precipitation by dosing Na2CO3 stepwise to various pH values (Sun et al. 2003). This study was. carried out to further characterize the formation of primary precipitates during the early stages of copper precipitation and simultaneous removal of Cr(VI) with Cu(II).<br /><br /><strong>METHODS: </strong>Test metal-solutions were prepared with industrial grade chemicals: CuCl2 x 2H2O, Na2SO4 and K2Cr2207. NaCO3 was added drop-wise to synthetic metal-solution to progressively increase pH. For each pH increment, removal of soluble metals was detected by atomic absorption spectrophotometer (AAS) and surface morphology of precipitates was analyzed by scanning electron microscope (SEM). To further characterize the formation of primary precipitates, a series of MINEQL+ thermodynamic calculations/analyses and equilibrium calculations/ analyses were conducted.<br /><br /><strong>RESULTS AND DISCUSSION: </strong>MINEQL+ thermodynamic calculation indicated that, for a system containing 150 mg/L Cu(II) and 60 mg/L Cr(VI) with gradual Na2CO3 dosing, if any precipitates can be formed at pH 5.0 or lower, it should be in the form of CuCrO4. Comparison tests using systems containing the same equivalent of Cu(II) plus Cr(VI) and Cu(II) plus SO4(2-) showed that the precipitation occurred at a pH of around 5.0 in the Cu(II)-Cr(VI) system and around 6.0 in the Cu(II)-SO4(2-) system. The discrepancy of the precipitation was indeed caused by the formation of Cu-Cr precipitates. The initiation of copper removal at pH around 5.0 for the Cu-Cr co-removal test was not attributable to the formation of Cu-CO3 precipitates, instead, it was most likely through the formation of insoluble Cu-Cr precipitates, such as CuCrO4 and CuCrO4 x 2Cu(OH)2. Experimental tests, equilibrium calculations, MINEQL+ thermodynamic calculations and surface morphologies for systems using higher concentrations of Cu(II) and Cr(VI) further verified the most probable composition of primary precipitates is copper-chromate.<br /><br /><strong>CONCLUSION: </strong>In the Cu-Cr co-removal test with Na2O3 dosing to increase pH and induce metal precipitation, copper-chromate precipitates are the primary precipitates produced and contribute to the initial simultaneous removal of copper and chromium.","Characterization of primary precipitate composition formed during co-removal of Cr(VI) with Cu(II) in synthetic wastewater Abs: <strong>BACKGROUND, AIMS AND SCOPE: </strong>Hexavalent chromium [Cr(VI)] cannot react with either carbonate or hydroxide to form chromium precipitates. However, by using a precipitation technology to treat plating wastewater containing Cr(VI), Cu(II), Ni(II) and Zn(II), approximately 78% of Cr(VI) (initial 60 mg/L) was co-removed with the precipitation of Cu(II), Ni(II) and Zn(II) (each 150 mg/L) by dosing with Na2CO3 (Sun 2003). Direct precipitation by forming Cu(II)-Cr(VI) precipitates followed by adsorption of Cr(VI) onto freshly formed Cu-precipitates was subsequently found to be the main mechanism(s) involved in Cr(VI) co-removal with Cu(II) precipitation by dosing Na2CO3 stepwise to various pH values (Sun et al. 2003). This study was. carried out to further characterize the formation of primary precipitates during the early stages of copper precipitation and simultaneous removal of Cr(VI) with Cu(II).<br /><br /><strong>METHODS: </strong>Test metal-solutions were prepared with industrial grade chemicals: CuCl2 x 2H2O, Na2SO4 and K2Cr2207. NaCO3 was added drop-wise to synthetic metal-solution to progressively increase pH. For each pH increment, removal of soluble metals was detected by atomic absorption spectrophotometer (AAS) and surface morphology of precipitates was analyzed by scanning electron microscope (SEM). To further characterize the formation of primary precipitates, a series of MINEQL+ thermodynamic calculations/analyses and equilibrium calculations/ analyses were conducted.<br /><br /><strong>RESULTS AND DISCUSSION: </strong>MINEQL+ thermodynamic calculation indicated that, for a system containing 150 mg/L Cu(II) and 60 mg/L Cr(VI) with gradual Na2CO3 dosing, if any precipitates can be formed at pH 5.0 or lower, it should be in the form of CuCrO4. Comparison tests using systems containing the same equivalent of Cu(II) plus Cr(VI) and Cu(II) plus SO4(2-) showed that the precipitation occurred at a pH of around 5.0 in the Cu(II)-Cr(VI) system and around 6.0 in the Cu(II)-SO4(2-) system. The discrepancy of the precipitation was indeed caused by the formation of Cu-Cr precipitates. The initiation of copper removal at pH around 5.0 for the Cu-Cr co-removal test was not attributable to the formation of Cu-CO3 precipitates, instead, it was most likely through the formation of insoluble Cu-Cr precipitates, such as CuCrO4 and CuCrO4 x 2Cu(OH)2. Experimental tests, equilibrium calculations, MINEQL+ thermodynamic calculations and surface morphologies for systems using higher concentrations of Cu(II) and Cr(VI) further verified the most probable composition of primary precipitates is copper-chromate.<br /><br /><strong>CONCLUSION: </strong>In the Cu-Cr co-removal test with Na2O3 dosing to increase pH and induce metal precipitation, copper-chromate precipitates are the primary precipitates produced and contribute to the initial simultaneous removal of copper and chromium."
1231780,Rajesh et al. 2007,Solid phase extraction of chromium(VI) from aqueous solutions by adsorption of its ion-association complex with cetyltrimethylammoniumbromide on an alumina column,"A simple approach has been developed for the solid phase extraction of chromium(VI) based on the adsorption of its ion-association complex with cetyltrimethylammoniumbromide (CTABr) on an alumina column. The effect of various parameters such as acidity, stability of the column, sample volume, effect of diverse ions, etc. have been studied in detail. The adsorbed complex could be eluted using sodium hydroxide and the concentration of chromium has been established using visible spectrophotometry after complexation with diphenyl carbazide. The calibration graph was linear in the range 0-0.5 microg mL(-1) chromium(VI) with a detection limit of 5 microg L(-1). A highest preconcentration factor of 25 could be obtained for 250 mL sample volume. The data from the column studies were also studied using the Thomas model of adsorption. The experimental results obtained were correlated with the proposed model of adsorption. The Thomas rate constant k was found to be 0.0025 L/min mg and the maximum adsorption capacity q(o) was found to be 0.36 mgCr/g alumina at an initial chromium(VI) concentration of 1 mg L(-1). The validity of the method has been checked by applying it to study the recovery of chromium in spiked water samples and electroplating wastewater.","Solid phase extraction of chromium(VI) from aqueous solutions by adsorption of its ion-association complex with cetyltrimethylammoniumbromide on an alumina column Abs: A simple approach has been developed for the solid phase extraction of chromium(VI) based on the adsorption of its ion-association complex with cetyltrimethylammoniumbromide (CTABr) on an alumina column. The effect of various parameters such as acidity, stability of the column, sample volume, effect of diverse ions, etc. have been studied in detail. The adsorbed complex could be eluted using sodium hydroxide and the concentration of chromium has been established using visible spectrophotometry after complexation with diphenyl carbazide. The calibration graph was linear in the range 0-0.5 microg mL(-1) chromium(VI) with a detection limit of 5 microg L(-1). A highest preconcentration factor of 25 could be obtained for 250 mL sample volume. The data from the column studies were also studied using the Thomas model of adsorption. The experimental results obtained were correlated with the proposed model of adsorption. The Thomas rate constant k was found to be 0.0025 L/min mg and the maximum adsorption capacity q(o) was found to be 0.36 mgCr/g alumina at an initial chromium(VI) concentration of 1 mg L(-1). The validity of the method has been checked by applying it to study the recovery of chromium in spiked water samples and electroplating wastewater."
1231779,Jemec et al. 2007,The applicability of acetylcholinesterase and glutathione S-transferase in Daphnia magna toxicity test,"The most commonly used toxicity test worldwide is the acute Daphnia magna test. The relevance of acetylcholinesterase (AChE) and glutathione S-transferase (GST) activity in D. magna exposed to chromium, cadmium, and diazinon was evaluated in connection with this standard test. We found no link between enzyme activities and immobility. Concentrations of Cr(6+) up to 280 microg/L had no effect on AChE and GST activities, while 20% immobility was observed. At concentrations of 20-25 microg/L of Cd(2+) AChE activity was increased by about 50%. The effect of diazinon on both enzymes was insignificant up to concentrations that caused 27% immobility. Consequently, while the use of AChE and GST activities is recommended when the mode of action of chemicals is studied, the value of these biomarkers in routine acute toxicity tests is limited because the relationship between enzyme activities and immobility of D. magna exposed to different chemicals is unclear.","The applicability of acetylcholinesterase and glutathione S-transferase in Daphnia magna toxicity test Abs: The most commonly used toxicity test worldwide is the acute Daphnia magna test. The relevance of acetylcholinesterase (AChE) and glutathione S-transferase (GST) activity in D. magna exposed to chromium, cadmium, and diazinon was evaluated in connection with this standard test. We found no link between enzyme activities and immobility. Concentrations of Cr(6+) up to 280 microg/L had no effect on AChE and GST activities, while 20% immobility was observed. At concentrations of 20-25 microg/L of Cd(2+) AChE activity was increased by about 50%. The effect of diazinon on both enzymes was insignificant up to concentrations that caused 27% immobility. Consequently, while the use of AChE and GST activities is recommended when the mode of action of chemicals is studied, the value of these biomarkers in routine acute toxicity tests is limited because the relationship between enzyme activities and immobility of D. magna exposed to different chemicals is unclear."
1231777,Quinteros et al. 2007,In vivo and in vitro effects of chromium VI on anterior pituitary hormone release and cell viability,"Hexavalent chromium (Cr VI) is a highly toxic metal and an environmental pollutant. Different studies indicate that Cr VI exposure adversely affects reproductive functions. This metal has been shown to affect several tissues and organs but Cr VI effects on pituitary gland have not been reported. Anterior pituitary hormones are central for the body homeostasis and have a fundamental role in reproductive physiology. The aim of this study was to evaluate the effect of Cr VI at the pituitary level both in vivo and in vitro. We showed that Cr VI accumulates in the pituitary and hypothalamus, and decreases serum prolactin levels in vivo but observed no effects on LH levels. In anterior pituitary cells in culture, the effect of Cr VI on hormone secretion followed the same differential pattern. Besides, lactotrophs were more sensitive to the toxicity of the metal. As a result of oxidative stress generation, Cr VI induced apoptosis evidenced by nuclear fragmentation and caspase 3 activation. Our results indicate that the anterior pituitary gland can be a target of Cr VI toxicity in vivo and in vitro, thus producing a negative impact on the hypothalamic-pituitary-gonadal axis and affecting the normal endocrine function.","In vivo and in vitro effects of chromium VI on anterior pituitary hormone release and cell viability Abs: Hexavalent chromium (Cr VI) is a highly toxic metal and an environmental pollutant. Different studies indicate that Cr VI exposure adversely affects reproductive functions. This metal has been shown to affect several tissues and organs but Cr VI effects on pituitary gland have not been reported. Anterior pituitary hormones are central for the body homeostasis and have a fundamental role in reproductive physiology. The aim of this study was to evaluate the effect of Cr VI at the pituitary level both in vivo and in vitro. We showed that Cr VI accumulates in the pituitary and hypothalamus, and decreases serum prolactin levels in vivo but observed no effects on LH levels. In anterior pituitary cells in culture, the effect of Cr VI on hormone secretion followed the same differential pattern. Besides, lactotrophs were more sensitive to the toxicity of the metal. As a result of oxidative stress generation, Cr VI induced apoptosis evidenced by nuclear fragmentation and caspase 3 activation. Our results indicate that the anterior pituitary gland can be a target of Cr VI toxicity in vivo and in vitro, thus producing a negative impact on the hypothalamic-pituitary-gonadal axis and affecting the normal endocrine function."
1231776,Shashidhar et al. 2007,Development and validation of a model of bio-barriers for remediation of Cr(VI) contaminated aquifers using laboratory column experiments,"Bench scale transport and biotransformation experiments and mathematical model simulations were carried out to study the effectiveness of bio-barriers for the containment of hexavalent chromium in contaminated confined aquifers. Experimental results showed that a 10cm thick bio-barrier with an initial biomass concentration of 0.205mg/g of soil was able to completely contain a Cr(VI) plume of 25mg/L concentration. It was also observed that pore water velocity and initial biomass concentration are the most significant parameters in the containment of Cr(VI). The mathematical model developed is based on one-dimensional advection-dispersion reaction equations for Cr(VI) and molasses in saturated, homogeneous porous medium. The transport of Cr(VI) and molasses is coupled with adsorption and Monod's inhibition kinetics for immobile bacteria. It was found that, in general, the model was able to simulate the experimental results satisfactorily. However, there was disparity between the numerically simulated and experimental breakthrough curves for Cr(VI) and molasses in cases where there was high clay content and high microbial activity. The mathematical model could contribute towards improved designs of future bio-barriers for the remediation of Cr(VI) contaminated aquifers.","Development and validation of a model of bio-barriers for remediation of Cr(VI) contaminated aquifers using laboratory column experiments Abs: Bench scale transport and biotransformation experiments and mathematical model simulations were carried out to study the effectiveness of bio-barriers for the containment of hexavalent chromium in contaminated confined aquifers. Experimental results showed that a 10cm thick bio-barrier with an initial biomass concentration of 0.205mg/g of soil was able to completely contain a Cr(VI) plume of 25mg/L concentration. It was also observed that pore water velocity and initial biomass concentration are the most significant parameters in the containment of Cr(VI). The mathematical model developed is based on one-dimensional advection-dispersion reaction equations for Cr(VI) and molasses in saturated, homogeneous porous medium. The transport of Cr(VI) and molasses is coupled with adsorption and Monod's inhibition kinetics for immobile bacteria. It was found that, in general, the model was able to simulate the experimental results satisfactorily. However, there was disparity between the numerically simulated and experimental breakthrough curves for Cr(VI) and molasses in cases where there was high clay content and high microbial activity. The mathematical model could contribute towards improved designs of future bio-barriers for the remediation of Cr(VI) contaminated aquifers."
1231775,Molokwanne and  Chirwa 2006,"Biological Cr(VI) reduction in indigenous sludge cultures from Gauteng, South africa","The Cr(VI) reducing capability of an acclimated indigenous culture cultivated from primary sludge was evaluated in batch and packed-bed bioreactor systems. Performance evaluation was carried out in unmodified cultures, cultures modified by substituting terminal organisms in the consortium by a known Cr(VI)-reducing organism (Escherichia coli ATCC 33456), and pure cultures of Cr(VI)-reducing organisms. A high Cr(VI) reduction rate was observed in modified cultures and in the pure culture of the Cr(VI)-reducing bacteria (Bacillus sp.). Furthermore, the Bacillus sp. pure culture outperformed both the unmodified and modified consortium cultures in reducing Cr(VI). Abiotic Cr(VI) reduction activity was evaluated in heat-killed and azide (N3) inactivated control cultures. No significant Cr(VI) reduction was observed in the controls. This study is part of the continuing research to identify synergistic culture systems for treating toxic compounds from polluted environments.","Biological Cr(VI) reduction in indigenous sludge cultures from Gauteng, South africa Abs: The Cr(VI) reducing capability of an acclimated indigenous culture cultivated from primary sludge was evaluated in batch and packed-bed bioreactor systems. Performance evaluation was carried out in unmodified cultures, cultures modified by substituting terminal organisms in the consortium by a known Cr(VI)-reducing organism (Escherichia coli ATCC 33456), and pure cultures of Cr(VI)-reducing organisms. A high Cr(VI) reduction rate was observed in modified cultures and in the pure culture of the Cr(VI)-reducing bacteria (Bacillus sp.). Furthermore, the Bacillus sp. pure culture outperformed both the unmodified and modified consortium cultures in reducing Cr(VI). Abiotic Cr(VI) reduction activity was evaluated in heat-killed and azide (N3) inactivated control cultures. No significant Cr(VI) reduction was observed in the controls. This study is part of the continuing research to identify synergistic culture systems for treating toxic compounds from polluted environments."
1231773,Svecevicius 2006,Acute toxicity of hexavalent chromium to European freshwater fish,,Acute toxicity of hexavalent chromium to European freshwater fish Abs: 
1231769,Deiana et al. 2007,Reduction of Cr(VI) by caffeic acid,"In the soil-plant system, the Cr(VI) toxicity can be moderated through redox reactions involving phenolic substances. In such a context, we report the reducing activity of caffeic acid (CAF) towards Cr(VI) in aqueous phase. The redox reaction between Cr(VI) and CAF was studied as a function of both time and pH at different initial metal concentrations. The reaction was particularly effective at pH 2.5. The kinetic data indicate that the reaction proceeds through two steps: the first is faster and involves four electrons, the latter, which is slower, five electrons. The chromatograms evidence the formation of oxidation products (OP) with a different redox activity towards Cr(VI). A yield of Cr(III) equal to that obtained at pH 2.5 and pH 3.1 in about 7 and 25 h, respectively, was reached at pH 4.2 only after a much longer reaction time (50h). At pH&gt;4.2 the reaction occurred even more slowly, and its kinetic trend was more and more difficult to study at pH values higher than 5.0 due to the formation of precipitates. Other phenolics investigated (o-, m-, p-coumaric acids) showed a reducing activity negligible compared to that of CAF: about 30% of p-coumaric acid was oxidized at pH 2.5 only after two months of reaction.","Reduction of Cr(VI) by caffeic acid Abs: In the soil-plant system, the Cr(VI) toxicity can be moderated through redox reactions involving phenolic substances. In such a context, we report the reducing activity of caffeic acid (CAF) towards Cr(VI) in aqueous phase. The redox reaction between Cr(VI) and CAF was studied as a function of both time and pH at different initial metal concentrations. The reaction was particularly effective at pH 2.5. The kinetic data indicate that the reaction proceeds through two steps: the first is faster and involves four electrons, the latter, which is slower, five electrons. The chromatograms evidence the formation of oxidation products (OP) with a different redox activity towards Cr(VI). A yield of Cr(III) equal to that obtained at pH 2.5 and pH 3.1 in about 7 and 25 h, respectively, was reached at pH 4.2 only after a much longer reaction time (50h). At pH&gt;4.2 the reaction occurred even more slowly, and its kinetic trend was more and more difficult to study at pH values higher than 5.0 due to the formation of precipitates. Other phenolics investigated (o-, m-, p-coumaric acids) showed a reducing activity negligible compared to that of CAF: about 30% of p-coumaric acid was oxidized at pH 2.5 only after two months of reaction."
1231768,Yu et al. 2007,Hexavalent chromium induced stress and metabolic responses in hybrid willows,"Metabolic responses to hexavalent chromium (Cr(6+)) stress and the uptake and translocation of Cr(6+ )were investigated using pre-rooted hybrid willows (Salix matsudana Koidz x Salix alba L.) exposed to hydroponic solution spiked with K(2)CrO(4) at 24.0 +/- 1 degrees C for 192 h. Various physiological parameters of the plants were monitored to determine toxicity from Cr(6+ )exposure. At Cr(6+) treatments of &lt;or=2.1 mg Cr/l, the transpiration rate of plants was &gt; 50% higher than that of the non-treated control plants. As Cr concentrations were increased further, a slight increase in the transpiration rate was also observed compared with the controls. Negligible difference in the chlorophyll contents in leaves between the treated and the non-treated control plants was measured, except for willows exposed to 1.05 mg Cr/l. The response of soluble proteins in leaves of willows to Cr treatments was remarkable. Cr-induced toxicity appeared in all treatments resulting in reduced activities of catalase (CAT) and peroxidase (POD) compared to the controls. Superoxide dismutases (SOD) activity in the leaf cells showed a positive increase after Cr exposure. Of all selected parameters, soluble proteins in leaves were the most sensitive to Cr(6+ )doses, showing a significant linear correlation negatively (R (2) = 0.931). Uptake of Cr(6+) by willows grown in flasks was found to increase linearly with the added Cr(6+ )(a zero order kinetics), as indicated by the high R (2) (0.9322). Recovery of Cr in different parts of plant materials varied significantly with roots being the dominant site of Cr accumulation. Although the translocation to shoots was detected, the amount of Cr translocated to shoots was considerably small. The capacity of willows to assimilate Cr(6+ )was also evaluated using detached leaves and roots in sealed glass vessels in vivo. Uptake of Cr by roots was mediated possibly through an active transport mechanism, whereas the cuticle of leaves was the major obstacle to uptake Cr from the hydroponic solution. In addition, both cysteine and ascorbic acid showed a remarkable potential to reduce Cr(6+) at a neutral pH. Results indicated that the added Cr did not cause deleterious effects on plant physiological functions over a 192-h period of exposure. Significant removal of Cr from the hydroponic solution was observed in the presence of hybrid willows. The data also suggest that phytoremediation of Cr(6+) is possible and ecologically safe due to the minor translocation of Cr to aerial tissues.","Hexavalent chromium induced stress and metabolic responses in hybrid willows Abs: Metabolic responses to hexavalent chromium (Cr(6+)) stress and the uptake and translocation of Cr(6+ )were investigated using pre-rooted hybrid willows (Salix matsudana Koidz x Salix alba L.) exposed to hydroponic solution spiked with K(2)CrO(4) at 24.0 +/- 1 degrees C for 192 h. Various physiological parameters of the plants were monitored to determine toxicity from Cr(6+ )exposure. At Cr(6+) treatments of &lt;or=2.1 mg Cr/l, the transpiration rate of plants was &gt; 50% higher than that of the non-treated control plants. As Cr concentrations were increased further, a slight increase in the transpiration rate was also observed compared with the controls. Negligible difference in the chlorophyll contents in leaves between the treated and the non-treated control plants was measured, except for willows exposed to 1.05 mg Cr/l. The response of soluble proteins in leaves of willows to Cr treatments was remarkable. Cr-induced toxicity appeared in all treatments resulting in reduced activities of catalase (CAT) and peroxidase (POD) compared to the controls. Superoxide dismutases (SOD) activity in the leaf cells showed a positive increase after Cr exposure. Of all selected parameters, soluble proteins in leaves were the most sensitive to Cr(6+ )doses, showing a significant linear correlation negatively (R (2) = 0.931). Uptake of Cr(6+) by willows grown in flasks was found to increase linearly with the added Cr(6+ )(a zero order kinetics), as indicated by the high R (2) (0.9322). Recovery of Cr in different parts of plant materials varied significantly with roots being the dominant site of Cr accumulation. Although the translocation to shoots was detected, the amount of Cr translocated to shoots was considerably small. The capacity of willows to assimilate Cr(6+ )was also evaluated using detached leaves and roots in sealed glass vessels in vivo. Uptake of Cr by roots was mediated possibly through an active transport mechanism, whereas the cuticle of leaves was the major obstacle to uptake Cr from the hydroponic solution. In addition, both cysteine and ascorbic acid showed a remarkable potential to reduce Cr(6+) at a neutral pH. Results indicated that the added Cr did not cause deleterious effects on plant physiological functions over a 192-h period of exposure. Significant removal of Cr from the hydroponic solution was observed in the presence of hybrid willows. The data also suggest that phytoremediation of Cr(6+) is possible and ecologically safe due to the minor translocation of Cr to aerial tissues."
1231767,Cummings et al. 2007,Reduction of Cr(VI) under acidic conditions by the facultative Fe(lll)-reducing bacterium Acidiphilium cryptum,"The potential for biological reduction of Cr(VI) under acidic conditions was evaluated with the acidophilic, facultatively metal-reducing bacterium Acidiphilium cryptum strain JF-5 to explore the role of acidophilic microorganisms in the Cr cycle in low-pH environments. An anaerobic suspension of washed A. cryptum cells rapidly reduced 50 microM Cr(VI) at pH 3.2; biological reduction was detected from pH 1.7-4.7. The reduction product, confirmed by XANES analysis, was entirely Cr(III) that was associated predominantly with the cell biomass (70-80%) with the residual residing in the aqueous phase. Reduction of Cr(VI) showed a pH optimum similar to that for growth and was inhibited by 5 mM HgCl2, suggesting that the reaction was enzyme-mediated. Introduction of O2 into the reaction medium slowed the reduction rate only slightly, whereas soluble Fe(III) (as ferric sulfate) increased the rate dramatically, presumably by the shuttling of electrons from bioreduced Fe(II) to Cr(VI) in a coupled biotic-abiotic cycle. Starved cells could not reduce Cr(VI) when provided as sole electron acceptor, indicating that Cr(VI) reduction is not an energy-conserving process in A. cryptum. We speculate, rather, that Cr(VI) reduction is used here as a detoxification mechanism.","Reduction of Cr(VI) under acidic conditions by the facultative Fe(lll)-reducing bacterium Acidiphilium cryptum Abs: The potential for biological reduction of Cr(VI) under acidic conditions was evaluated with the acidophilic, facultatively metal-reducing bacterium Acidiphilium cryptum strain JF-5 to explore the role of acidophilic microorganisms in the Cr cycle in low-pH environments. An anaerobic suspension of washed A. cryptum cells rapidly reduced 50 microM Cr(VI) at pH 3.2; biological reduction was detected from pH 1.7-4.7. The reduction product, confirmed by XANES analysis, was entirely Cr(III) that was associated predominantly with the cell biomass (70-80%) with the residual residing in the aqueous phase. Reduction of Cr(VI) showed a pH optimum similar to that for growth and was inhibited by 5 mM HgCl2, suggesting that the reaction was enzyme-mediated. Introduction of O2 into the reaction medium slowed the reduction rate only slightly, whereas soluble Fe(III) (as ferric sulfate) increased the rate dramatically, presumably by the shuttling of electrons from bioreduced Fe(II) to Cr(VI) in a coupled biotic-abiotic cycle. Starved cells could not reduce Cr(VI) when provided as sole electron acceptor, indicating that Cr(VI) reduction is not an energy-conserving process in A. cryptum. We speculate, rather, that Cr(VI) reduction is used here as a detoxification mechanism."
1231766,Bencheikh-Latmani et al. 2007,Toxicity of Cr(lll) to Shewanella sp. strain MR-4 during Cr(VI) reduction,"Bioremediation of chromium through the reduction of hexavalent chromium (as the chromate ion, CrO42-) is based on the notion that the product, trivalent chromium (Cr(III)), is less toxic than chromate. In this study, we show that soluble Cr(III), present at pH 6-8 as the Cr3+ ion and/or hydroxyl complexes (henceforth referred to as uncomplexed Cr(III)), can be found transiently in significant concentrations and has a deleterious effect on Shewanella sp. MR-4. However, Cr(lll) complexed to an organic ligand or precipitated as Cr(OH)3(s) has little or no effect on cells. Similarly, during the reduction of Cr(VI) by strain MR-4, complexation of the product, Cr(lll), results in increased cell survival and extended Cr(VI) reduction activity. These results and gene expression data obtained by qRT-PCR (quantitative reverse transcription-PCR) suggestthatthe observed toxic effect of Cr(II) formed during Cr(VI) reduction or added as an uncomplexed species is due to the interference with basic cell activities such as DNA transcription and/or replication. Important implications for the bioremediation of Cr(VI)-contaminated sites emerge from this study: Cr(VI) reduction by Shewanella sp. MR-4 is enhanced and sustained by the presence of compounds able to complex Cr(III) as it is being formed but, in turn, the complexation of Cr(III) precludes its precipitation and immobilization.","Toxicity of Cr(lll) to Shewanella sp. strain MR-4 during Cr(VI) reduction Abs: Bioremediation of chromium through the reduction of hexavalent chromium (as the chromate ion, CrO42-) is based on the notion that the product, trivalent chromium (Cr(III)), is less toxic than chromate. In this study, we show that soluble Cr(III), present at pH 6-8 as the Cr3+ ion and/or hydroxyl complexes (henceforth referred to as uncomplexed Cr(III)), can be found transiently in significant concentrations and has a deleterious effect on Shewanella sp. MR-4. However, Cr(lll) complexed to an organic ligand or precipitated as Cr(OH)3(s) has little or no effect on cells. Similarly, during the reduction of Cr(VI) by strain MR-4, complexation of the product, Cr(lll), results in increased cell survival and extended Cr(VI) reduction activity. These results and gene expression data obtained by qRT-PCR (quantitative reverse transcription-PCR) suggestthatthe observed toxic effect of Cr(II) formed during Cr(VI) reduction or added as an uncomplexed species is due to the interference with basic cell activities such as DNA transcription and/or replication. Important implications for the bioremediation of Cr(VI)-contaminated sites emerge from this study: Cr(VI) reduction by Shewanella sp. MR-4 is enhanced and sustained by the presence of compounds able to complex Cr(III) as it is being formed but, in turn, the complexation of Cr(III) precludes its precipitation and immobilization."
1231763,Wazne et al. 2007,Assessment of calcium polysulfide for the remediation of hexavalent chromium in chromite ore processing residue (COPR),"Bench scale and pilot scale treatability studies were conducted to evaluate the remediation of hexavalent chromium [Cr(VI)] in chromite ore processing residue (COPR) using calcium polysulfide. The results from the bench scale study indicated that a calcium polysulfide dosage twice the molar stoichiometric requirement (2x) proved effective in meeting the New Jersey Department of Environmental Protection (NJDEP) total Cr(VI) and the Environmental Protection Agency (EPA) Toxicity Characteristic Leaching Procedure (TCLP) regulatory standards. The treatment results were more effective at pH 12 than at pH 9.5. X-ray powder diffraction (XRPD) and X-ray absorption near edge structure (XANES) spectroscopy were also used to assess the treatment performance. Based on the bench scale results, an ex-situ pugmill pilot program was implemented to evaluate the applicability of the calcium polysulfide treatment on a larger scale (1000-lb batch test). The pugmill treatment results met Cr(VI) and TCLP regulatory standards over a period of 15 months. XANES analysis indicated that approximately 62% of Cr(VI) was reduced by calcium polysulfide at stoichiometric ratio of 2x after a curing period of 10 months.","Assessment of calcium polysulfide for the remediation of hexavalent chromium in chromite ore processing residue (COPR) Abs: Bench scale and pilot scale treatability studies were conducted to evaluate the remediation of hexavalent chromium [Cr(VI)] in chromite ore processing residue (COPR) using calcium polysulfide. The results from the bench scale study indicated that a calcium polysulfide dosage twice the molar stoichiometric requirement (2x) proved effective in meeting the New Jersey Department of Environmental Protection (NJDEP) total Cr(VI) and the Environmental Protection Agency (EPA) Toxicity Characteristic Leaching Procedure (TCLP) regulatory standards. The treatment results were more effective at pH 12 than at pH 9.5. X-ray powder diffraction (XRPD) and X-ray absorption near edge structure (XANES) spectroscopy were also used to assess the treatment performance. Based on the bench scale results, an ex-situ pugmill pilot program was implemented to evaluate the applicability of the calcium polysulfide treatment on a larger scale (1000-lb batch test). The pugmill treatment results met Cr(VI) and TCLP regulatory standards over a period of 15 months. XANES analysis indicated that approximately 62% of Cr(VI) was reduced by calcium polysulfide at stoichiometric ratio of 2x after a curing period of 10 months."
1231762,Dutta et al. 2006,Anticlastogenic effect of redistilled cow's urine distillate in human peripheral lymphocytes challenged with manganese dioxide and hexavalent chromium,"<strong>OBJECTIVE: </strong>To study the anticlastogenic effect of redistilled cow's urine distillate (RCUD) in human peripheral lymphocytes (HLC) challenged with manganese dioxide and hexavalent chromium.<br /><br /><strong>METHODS: </strong>The anticlastogenic activity of redistilled cow's urine distillate was studied in human polymorphonuclear leukocytes (HPNLs) and human peripheral lymphocytes in vitro challenged with manganese dioxide and hexavalent chromium as established genotoxicants and clastogens which could cause induction of DNA strand break, chromosomal aberration and micronucleus. Three different levels of RCUD: 1 microL/mL, 50 microL/mL and 100 microL/mL, were used in the study.<br /><br /><strong>RESULTS: </strong>Manganese dioxide and hexavalent chromium caused statistically significant DNA strand break, chromosomal aberration and micronucleus formation, which could be protected by redistilled cow's urine distillate.<br /><br /><strong>CONCLUSION: </strong>The redistilled cow's urine distillate posseses strong antigenotoxic and anticlastogenic properties against HPNLs and HLC treated with Cr+6 and MnO2. This property is mainly due to the antioxidants present in RCUD.","Anticlastogenic effect of redistilled cow's urine distillate in human peripheral lymphocytes challenged with manganese dioxide and hexavalent chromium Abs: <strong>OBJECTIVE: </strong>To study the anticlastogenic effect of redistilled cow's urine distillate (RCUD) in human peripheral lymphocytes (HLC) challenged with manganese dioxide and hexavalent chromium.<br /><br /><strong>METHODS: </strong>The anticlastogenic activity of redistilled cow's urine distillate was studied in human polymorphonuclear leukocytes (HPNLs) and human peripheral lymphocytes in vitro challenged with manganese dioxide and hexavalent chromium as established genotoxicants and clastogens which could cause induction of DNA strand break, chromosomal aberration and micronucleus. Three different levels of RCUD: 1 microL/mL, 50 microL/mL and 100 microL/mL, were used in the study.<br /><br /><strong>RESULTS: </strong>Manganese dioxide and hexavalent chromium caused statistically significant DNA strand break, chromosomal aberration and micronucleus formation, which could be protected by redistilled cow's urine distillate.<br /><br /><strong>CONCLUSION: </strong>The redistilled cow's urine distillate posseses strong antigenotoxic and anticlastogenic properties against HPNLs and HLC treated with Cr+6 and MnO2. This property is mainly due to the antioxidants present in RCUD."
1231761,Borthiry et al. 2007,Reduction of hexavalent chromium by human cytochrome b5: generation of hydroxyl radical and superoxide,"The reduction of hexavalent chromium, Cr(VI), can generate reactive Cr intermediates and various types of oxidative stress. The potential role of human microsomal enzymes in free radical generation was examined using reconstituted proteoliposomes (PLs) containing purified cytochrome b(5) and NADPH:P450 reductase. Under aerobic conditions, the PLs reduced Cr(VI) to Cr(V) which was confirmed by ESR using isotopically pure (53)Cr(VI). When 5-diethoxyphosphoryl-5-methyl-1-pyrroline-N-oxide (DEPMPO) was included as a spin trap, a very prominent signal for the hydroxyl radical (HO()) adduct was observed as well as a smaller signal for the superoxide (O(2)(-)) adduct. These adducts were observed even at very low Cr(VI) concentrations (10 muM). NADPH, Cr(VI), O(2), and the PLs were all required for significant HO() generation. Superoxide dismutase eliminated the O(2)(-) adduct and resulted in a 30% increase in the HO() adduct. Catalase largely diminished the HO() adduct signal, indicating its dependence on H(2)O(2). Some sources of catalase were found to have Cr(VI)-reducing contaminants which could confound results, but a source of catalase free of these contaminants was used for these studies. Exogenous H(2)O(2) was not needed, indicating that it was generated by the PLs. Adding exogenous H(2)O(2), however, did increase the amount of DEPMPO/HO() adduct. The inclusion of formate yielded the carbon dioxide radical adduct of DEPMPO, and experiments with dimethyl sulfoxide (DMSO) plus the spin trap alpha-phenyl-N-tert-butylnitrone (PBN) yielded the methoxy and methyl radical adducts of PBN, confirming the generation of HO(). Quantification of the various species over time was consistent with a stoichiometric excess of HO() relative to the net amount of Cr(VI) reduced. This also represents the first demonstration of a role for cytochrome b(5) in the generation of HO(). Overall, the simultaneous generation of Cr(V) and H(2)O(2) by the PLs and the resulting generation of HO() at low Cr(VI) concentrations could have important implications for Cr(VI) toxicity.","Reduction of hexavalent chromium by human cytochrome b5: generation of hydroxyl radical and superoxide Abs: The reduction of hexavalent chromium, Cr(VI), can generate reactive Cr intermediates and various types of oxidative stress. The potential role of human microsomal enzymes in free radical generation was examined using reconstituted proteoliposomes (PLs) containing purified cytochrome b(5) and NADPH:P450 reductase. Under aerobic conditions, the PLs reduced Cr(VI) to Cr(V) which was confirmed by ESR using isotopically pure (53)Cr(VI). When 5-diethoxyphosphoryl-5-methyl-1-pyrroline-N-oxide (DEPMPO) was included as a spin trap, a very prominent signal for the hydroxyl radical (HO()) adduct was observed as well as a smaller signal for the superoxide (O(2)(-)) adduct. These adducts were observed even at very low Cr(VI) concentrations (10 muM). NADPH, Cr(VI), O(2), and the PLs were all required for significant HO() generation. Superoxide dismutase eliminated the O(2)(-) adduct and resulted in a 30% increase in the HO() adduct. Catalase largely diminished the HO() adduct signal, indicating its dependence on H(2)O(2). Some sources of catalase were found to have Cr(VI)-reducing contaminants which could confound results, but a source of catalase free of these contaminants was used for these studies. Exogenous H(2)O(2) was not needed, indicating that it was generated by the PLs. Adding exogenous H(2)O(2), however, did increase the amount of DEPMPO/HO() adduct. The inclusion of formate yielded the carbon dioxide radical adduct of DEPMPO, and experiments with dimethyl sulfoxide (DMSO) plus the spin trap alpha-phenyl-N-tert-butylnitrone (PBN) yielded the methoxy and methyl radical adducts of PBN, confirming the generation of HO(). Quantification of the various species over time was consistent with a stoichiometric excess of HO() relative to the net amount of Cr(VI) reduced. This also represents the first demonstration of a role for cytochrome b(5) in the generation of HO(). Overall, the simultaneous generation of Cr(V) and H(2)O(2) by the PLs and the resulting generation of HO() at low Cr(VI) concentrations could have important implications for Cr(VI) toxicity."
1231760,Mandiwana et al. 2007,Electrothermal atomic absorption spectrometric determination of Cr(VI) during ferrochrome production,"The level of the generation of hexavalent chromium during ferrochrome production was checked. The concentration of Cr(VI) increases with each stage of ferrochrome production, 7070microgg(-1) being the highest concentration encountered in the last stage of production (dust). This concentration exceeds the maximum acceptable total Cr concentration per 8h by a factor of more than 1000. It was further observed that there is a higher contamination of soil by this pollutant closer to the plant than further away. The highest concentrations of Cr(VI) in soil and grass were found to be 12.7 and 4.2microgg(-1), respectively. The results of the investigation indicate that the consumption of such grass by animals do not pose any health hazard, for concentrations of the toxic Cr species are very low. Therefore, the release of emissions, including dust, during ferrochrome production, is a major contributor to occupational diseases and death to people working in ferrochrome production plant or mine.","Electrothermal atomic absorption spectrometric determination of Cr(VI) during ferrochrome production Abs: The level of the generation of hexavalent chromium during ferrochrome production was checked. The concentration of Cr(VI) increases with each stage of ferrochrome production, 7070microgg(-1) being the highest concentration encountered in the last stage of production (dust). This concentration exceeds the maximum acceptable total Cr concentration per 8h by a factor of more than 1000. It was further observed that there is a higher contamination of soil by this pollutant closer to the plant than further away. The highest concentrations of Cr(VI) in soil and grass were found to be 12.7 and 4.2microgg(-1), respectively. The results of the investigation indicate that the consumption of such grass by animals do not pose any health hazard, for concentrations of the toxic Cr species are very low. Therefore, the release of emissions, including dust, during ferrochrome production, is a major contributor to occupational diseases and death to people working in ferrochrome production plant or mine."
1231759,Olad and  Nabavi 2007,Application of polyaniline for the reduction of toxic Cr(VI) in water,"Various oxidation states of polyaniline, as film and powder, were used for reduction of highly toxic Cr(VI) to less toxic Cr(III) ion. The effects of various parameters such as synthesis method, physical and oxidation state of polyaniline, film thickness, solution pH and initial Cr(VI) concentration on the kinetics and efficiency of reduction process were investigated. Results showed that a very broad concentration range of Cr(VI) solutions (10-10(5)ppb by emeraldine base and 10-10(6.5)ppb by leucoemeraldine) can be efficiently (&gt;98%) reduced by polyaniline as film or powder. Cr(VI) solutions with concentrations higher than these ranges were caused to the overoxidation and degradation of polymer. Decreasing of solution pH, increased the kinetics and performance of reduction process, but lowered the Cr(VI) concentration ranges caused the overoxidation and degradation of the polymer. Higher reduction efficiencies were obtained for thicker electrochemically synthesized polyaniline films and for thinner chemically prepared polyaniline free standing films. The ability or capacity of various forms of polyaniline in Cr(VI) reduction was evaluated as the milligrams of Cr(VI) reduced by one gram of various forms of polyaniline.","Application of polyaniline for the reduction of toxic Cr(VI) in water Abs: Various oxidation states of polyaniline, as film and powder, were used for reduction of highly toxic Cr(VI) to less toxic Cr(III) ion. The effects of various parameters such as synthesis method, physical and oxidation state of polyaniline, film thickness, solution pH and initial Cr(VI) concentration on the kinetics and efficiency of reduction process were investigated. Results showed that a very broad concentration range of Cr(VI) solutions (10-10(5)ppb by emeraldine base and 10-10(6.5)ppb by leucoemeraldine) can be efficiently (&gt;98%) reduced by polyaniline as film or powder. Cr(VI) solutions with concentrations higher than these ranges were caused to the overoxidation and degradation of polymer. Decreasing of solution pH, increased the kinetics and performance of reduction process, but lowered the Cr(VI) concentration ranges caused the overoxidation and degradation of the polymer. Higher reduction efficiencies were obtained for thicker electrochemically synthesized polyaniline films and for thinner chemically prepared polyaniline free standing films. The ability or capacity of various forms of polyaniline in Cr(VI) reduction was evaluated as the milligrams of Cr(VI) reduced by one gram of various forms of polyaniline."
1231758,Chang and  Kim 2007,Effect of sulfate reduction activity on biological treatment of hexavalent chromium [Cr(VI)] contaminated electroplating wastewater under sulfate-rich condition,"Electroplating wastewater (EW) containing heavy metals was treated by a two-stage packed-bed reactor system. The EW was highly contaminated with hexavalent chromium and other heavy metals as well as sulfate because sulfuric acid had been mainly used to polish the surface of metals to be electroplated. This acidic EW was effectively neutralized in an alkaline reactor where limestone had been packed. The neutralized wastewater together with organic wastewater from a starch-processing factory (SPW) was fed to a bioreactor packed with waste biomass. The SPW was used to supplement the electron donor in the sulfidogenic bioreactor. During the whole operation, we investigated the stoichiometry of electron to see what could be a major factor to remove Cr in the wastewater. The removal rates of sulfate and Cr(VI) were dependent on the consumption rate of organic materials in the wastewater. The stoichiometric studies also showed that about 63% of electrons from oxidation of organic materials were used to reduce sulfate. When the electrons of sulfide oxidation to elemental sulfur was at least 1.3 times higher than that of Cr(VI) reduction to Cr(III), Cr(VI) was completely removed. This result suggests that Cr(VI) reduction can be expected to take place under sulfate-rich anaerobic conditions, and sulfide produced by sulfate reducing bacteria could be used to immobilize soluble chromium through Cr(VI) reduction.","Effect of sulfate reduction activity on biological treatment of hexavalent chromium [Cr(VI)] contaminated electroplating wastewater under sulfate-rich condition Abs: Electroplating wastewater (EW) containing heavy metals was treated by a two-stage packed-bed reactor system. The EW was highly contaminated with hexavalent chromium and other heavy metals as well as sulfate because sulfuric acid had been mainly used to polish the surface of metals to be electroplated. This acidic EW was effectively neutralized in an alkaline reactor where limestone had been packed. The neutralized wastewater together with organic wastewater from a starch-processing factory (SPW) was fed to a bioreactor packed with waste biomass. The SPW was used to supplement the electron donor in the sulfidogenic bioreactor. During the whole operation, we investigated the stoichiometry of electron to see what could be a major factor to remove Cr in the wastewater. The removal rates of sulfate and Cr(VI) were dependent on the consumption rate of organic materials in the wastewater. The stoichiometric studies also showed that about 63% of electrons from oxidation of organic materials were used to reduce sulfate. When the electrons of sulfide oxidation to elemental sulfur was at least 1.3 times higher than that of Cr(VI) reduction to Cr(III), Cr(VI) was completely removed. This result suggests that Cr(VI) reduction can be expected to take place under sulfate-rich anaerobic conditions, and sulfide produced by sulfate reducing bacteria could be used to immobilize soluble chromium through Cr(VI) reduction."
1231757,El-Sikaily et al. 2007,Removal of toxic chromium from wastewater using green alga Ulva lactuca and its activated carbon,"Biosorption of heavy metals can be an effective process for the removal of toxic chromium ions from wastewater. In this study, the batch removal of toxic hexavalent chromium ions from aqueous solution, saline water and wastewater using marine dried green alga Ulva lactuca was investigated. Activated carbon prepared from U. lactuca by acid decomposition was also used for the removal of chromium from aqueous solution, saline water and wastewater. The chromium uptake was dependent on the initial pH and the initial chromium concentration, with pH approximately 1.0, being the optimum pH value. Langmuir, Freundlich, Redlich-Peterson and Koble-Corrigan isotherm models were fitted well the equilibrium data for both sorbents. The maximum efficiencies of chromium removal were 92 and 98% for U. lactuca and its activated carbon, respectively. The maximum adsorption capacity was found to be 10.61 and 112.36 mg g(-1) for dried green alga and activated carbon developed from it, respectively. The adsorption capacities of U. lactuca and its activated carbon were independent on the type of solution containing toxic chromium and the efficiency of removal was not affected by the replacing of aqueous solution by saline water or wastewater containing the same chromium concentration. Two hours were necessary to reach the sorption equilibrium. The chromium uptake by U. lactuca and its activated carbon form were best described by pseudo second-order rate model. This study verifies the possibility of using inactivated marine green alga U. lactuca and its activated carbon as valuable material for the removal of chromium from aqueous solutions, saline water or wastewater.","Removal of toxic chromium from wastewater using green alga Ulva lactuca and its activated carbon Abs: Biosorption of heavy metals can be an effective process for the removal of toxic chromium ions from wastewater. In this study, the batch removal of toxic hexavalent chromium ions from aqueous solution, saline water and wastewater using marine dried green alga Ulva lactuca was investigated. Activated carbon prepared from U. lactuca by acid decomposition was also used for the removal of chromium from aqueous solution, saline water and wastewater. The chromium uptake was dependent on the initial pH and the initial chromium concentration, with pH approximately 1.0, being the optimum pH value. Langmuir, Freundlich, Redlich-Peterson and Koble-Corrigan isotherm models were fitted well the equilibrium data for both sorbents. The maximum efficiencies of chromium removal were 92 and 98% for U. lactuca and its activated carbon, respectively. The maximum adsorption capacity was found to be 10.61 and 112.36 mg g(-1) for dried green alga and activated carbon developed from it, respectively. The adsorption capacities of U. lactuca and its activated carbon were independent on the type of solution containing toxic chromium and the efficiency of removal was not affected by the replacing of aqueous solution by saline water or wastewater containing the same chromium concentration. Two hours were necessary to reach the sorption equilibrium. The chromium uptake by U. lactuca and its activated carbon form were best described by pseudo second-order rate model. This study verifies the possibility of using inactivated marine green alga U. lactuca and its activated carbon as valuable material for the removal of chromium from aqueous solutions, saline water or wastewater."
1231756,Lee et al. 2007,Effects of the density of carboxyl groups in organic compounds on the photocatalytic reduction of Cr(VI) in a TiO2 suspension,"Photocatalytic reduction (PCR) of Cr(VI) in a TiO2 suspension was studied at pH 4 in the presence of organic compounds containing different numbers of carboxyl groups. The compounds studied were glycine (Gly), iminodiacetic acid (IDA), nitrilotriacetic acid (NTA), ethylenediaminetetraacetic acid (EDTA). In all the cases, near complete Cr(VI) removal was observed after 60 minutes. During PCR process, the aqueous Cr(VI) concentration measured with both Ion Chromatography and Atomic Absorption Spectrophotometery was different in the presence of IDA and EDTA as reaction proceeded while little difference was observed in a control test. This result suggests that a greater portion of reduced Cr(III) species was possibly dissolved through complex formation with IDA (Cr(III)-IDA) and EDTA (Cr(III)-EDTA) or with reaction intermediates (Cr(III)-organic complexes) during PCR compared to the control test. As the number of carboxyl group increased Cr(VI) reduction increased and showed a good linear relationship between initial rates of Cr(VI) reduction and adsorption density of carboxyl group of the surface of TiO2. The initial rate of Cr(VI) reduction in the presence of EDTA was 5 times greater than that in control. When the PCR process was applied in the treatment of real wastewater, an effective Cr(VI) reduction was observed with addition of EDTA.","Effects of the density of carboxyl groups in organic compounds on the photocatalytic reduction of Cr(VI) in a TiO2 suspension Abs: Photocatalytic reduction (PCR) of Cr(VI) in a TiO2 suspension was studied at pH 4 in the presence of organic compounds containing different numbers of carboxyl groups. The compounds studied were glycine (Gly), iminodiacetic acid (IDA), nitrilotriacetic acid (NTA), ethylenediaminetetraacetic acid (EDTA). In all the cases, near complete Cr(VI) removal was observed after 60 minutes. During PCR process, the aqueous Cr(VI) concentration measured with both Ion Chromatography and Atomic Absorption Spectrophotometery was different in the presence of IDA and EDTA as reaction proceeded while little difference was observed in a control test. This result suggests that a greater portion of reduced Cr(III) species was possibly dissolved through complex formation with IDA (Cr(III)-IDA) and EDTA (Cr(III)-EDTA) or with reaction intermediates (Cr(III)-organic complexes) during PCR compared to the control test. As the number of carboxyl group increased Cr(VI) reduction increased and showed a good linear relationship between initial rates of Cr(VI) reduction and adsorption density of carboxyl group of the surface of TiO2. The initial rate of Cr(VI) reduction in the presence of EDTA was 5 times greater than that in control. When the PCR process was applied in the treatment of real wastewater, an effective Cr(VI) reduction was observed with addition of EDTA."
1231755,Zakaria et al. 2007,Biological detoxification of Cr(VI) using wood-husk immobilized Acinetobacter haemolyticus,"Acinetobacter haemolyticus, a Gram-negative aerobic locally isolated bacterium, immobilized on wood-husk showed the ability to detoxify Cr(VI) to Cr(III). Wood-husk, a natural cellulose-based support material, packed in an upward-flow column was used as support material for bacterial attachment. Around 97% of the Cr(VI) in wastewater containing 15 mg L(-1) of Cr(VI) was reduced at a flow rate of 8.0 mL min(-1). The wastewater containing Cr(VI) was added with liquid pineapple wastewater as nutrient source for the bacteria. Electron microscopic examinations of the wood-husk after 42 days of column operation showed gradual colonization of the wood-husk by bacterial biofilm. The use of 0.1% (v/v) formaldehyde as a disinfecting agent inhibited growth of bacteria present in the final wastewater discharge. This finding is important in view of the ethical code regarding possible introduction of exogenous bacterial species into the environment.","Biological detoxification of Cr(VI) using wood-husk immobilized Acinetobacter haemolyticus Abs: Acinetobacter haemolyticus, a Gram-negative aerobic locally isolated bacterium, immobilized on wood-husk showed the ability to detoxify Cr(VI) to Cr(III). Wood-husk, a natural cellulose-based support material, packed in an upward-flow column was used as support material for bacterial attachment. Around 97% of the Cr(VI) in wastewater containing 15 mg L(-1) of Cr(VI) was reduced at a flow rate of 8.0 mL min(-1). The wastewater containing Cr(VI) was added with liquid pineapple wastewater as nutrient source for the bacteria. Electron microscopic examinations of the wood-husk after 42 days of column operation showed gradual colonization of the wood-husk by bacterial biofilm. The use of 0.1% (v/v) formaldehyde as a disinfecting agent inhibited growth of bacteria present in the final wastewater discharge. This finding is important in view of the ethical code regarding possible introduction of exogenous bacterial species into the environment."
1231754,Martí et al. 2007,Ecotoxicological tests assessment of soils polluted by chromium (VI) or pentachlorophenol,"Carbon mineralisation and plant germination and growth (Lactuca sativa seeds) tests have been performed in two soils of different properties, experimentally spiked with pentachlorophenol (PCP) or Cr (VI), in concentrations between 0.001 and 1000 mg kg(-1). The evaluation has been done considering the following parameters of carbon transformation test: soil cumulative basal respiration after 14 days incubation, substrate induced respiration after 12 h of glucose addition, and, in the plant germination and growth test: number of germinated seeds, root elongation and total biomass produced. The most sensitive assay found in our work has been carbon mineralisation test, from which the lowest toxic concentrations were obtained (especially substrate induced respiration test). In the plant germination and growth test, the measurement of root elongation has shown the best sensitiveness, followed by plant biomass and seed germination numbers. Regarding the contaminants, the highest toxicity, considering the minimum concentration with toxic effect, has been found in PCP (0.01 mg kg(-1)) in C mineralisation test in the granitic soil. For Cr, the minimum concentration with toxic effect has been 0.1 mg kg(-1), also in the C mineralisation test and the granitic soil. The granitic soil has shown more vulnerability to the pollutants assayed in the respiration test, whereas the calcareous soil has shown more vulnerability in the plant germination and growth test.","Ecotoxicological tests assessment of soils polluted by chromium (VI) or pentachlorophenol Abs: Carbon mineralisation and plant germination and growth (Lactuca sativa seeds) tests have been performed in two soils of different properties, experimentally spiked with pentachlorophenol (PCP) or Cr (VI), in concentrations between 0.001 and 1000 mg kg(-1). The evaluation has been done considering the following parameters of carbon transformation test: soil cumulative basal respiration after 14 days incubation, substrate induced respiration after 12 h of glucose addition, and, in the plant germination and growth test: number of germinated seeds, root elongation and total biomass produced. The most sensitive assay found in our work has been carbon mineralisation test, from which the lowest toxic concentrations were obtained (especially substrate induced respiration test). In the plant germination and growth test, the measurement of root elongation has shown the best sensitiveness, followed by plant biomass and seed germination numbers. Regarding the contaminants, the highest toxicity, considering the minimum concentration with toxic effect, has been found in PCP (0.01 mg kg(-1)) in C mineralisation test in the granitic soil. For Cr, the minimum concentration with toxic effect has been 0.1 mg kg(-1), also in the C mineralisation test and the granitic soil. The granitic soil has shown more vulnerability to the pollutants assayed in the respiration test, whereas the calcareous soil has shown more vulnerability in the plant germination and growth test."
1231753,Anjana et al. 2007,Biosorption of Cr(VI) by immobilized biomass of two indigenous strains of cyanobacteria isolated from metal contaminated soil,"Biosorption of Cr(VI) using native strains of cyanobacteria from metal contaminated soil in the premises of textile mill has been reported in this paper. Biosorption was studied as a function of pH (1-5), contact time (5-180 min) and initial chromium ion concentration (5-20mg/l) to find out the maximum biosorption capacity of alginate immobilized Nostoc calcicola HH-12 and Chroococcus sp. HH-11. The optimum conditions for Cr(VI) biosorption are almost same for the two strains (pH 3-4, contact time 30 min and initial chromium concentration of 20mg/l) however, the biomass of Chroococcus sp. HH-11 was found to be more suitable for the development of an efficient biosorbent for the removal of Cr(VI) from wastewater, as it showed higher values of q(m) and K(f), the Langmuir and Freundlich isotherm parameters. Both the isotherm models were suitable for describing the biosorption of Cr(VI) by the cyanobacterial biosorbents.","Biosorption of Cr(VI) by immobilized biomass of two indigenous strains of cyanobacteria isolated from metal contaminated soil Abs: Biosorption of Cr(VI) using native strains of cyanobacteria from metal contaminated soil in the premises of textile mill has been reported in this paper. Biosorption was studied as a function of pH (1-5), contact time (5-180 min) and initial chromium ion concentration (5-20mg/l) to find out the maximum biosorption capacity of alginate immobilized Nostoc calcicola HH-12 and Chroococcus sp. HH-11. The optimum conditions for Cr(VI) biosorption are almost same for the two strains (pH 3-4, contact time 30 min and initial chromium concentration of 20mg/l) however, the biomass of Chroococcus sp. HH-11 was found to be more suitable for the development of an efficient biosorbent for the removal of Cr(VI) from wastewater, as it showed higher values of q(m) and K(f), the Langmuir and Freundlich isotherm parameters. Both the isotherm models were suitable for describing the biosorption of Cr(VI) by the cyanobacterial biosorbents."
1231752,Jeen et al. 2007,Precipitates on granular iron in solutions containing calcium carbonate with trichloroethene and hexavalent chromium,"Mineralogical examination, using scanning electron microscopy (SEM), X-ray diffractometry (XRD), and optical microscopy, was conducted on the Fe0-bearing reactive materials derived from long-term column experiments undertaken to assess the treatment capacity of Fe0 under different geochemical conditions. The columns received either deionized water or solutions of differing dissolved calcium carbonate concentrations, together either with trichloroethene (TCE) or hexavalent chromium (Cr(VI)). The major reaction product in the columns receiving deionized water was magnetite-maghemite, and for the columns receiving dissolved calcium carbonate, the main products were iron hydroxy carbonate and aragonite. Replacement of Fe0 by reaction products occurred mainly at the edges of the Fe0 particles, and penetrative replacement was focused along cracks and along and around graphitic inclusions. Fibrous or flake-shaped iron hydroxy carbonate mostly replaced the edges of the Fe0 particles. Aragonite had needle-shaped morphology, and some occurred as clusters of crystals. Aragonite was deposited on iron hydroxy carbonate, thus providing at least a partial armoring effect. The mineral was also observed to cement groups of Fe0 particles into compact aggregates. The Cr was present mostly as Cr(III) in Cr(III)-Fe(III) (oxy)hydroxides and in trace amounts in iron hydroxy carbonate.","Precipitates on granular iron in solutions containing calcium carbonate with trichloroethene and hexavalent chromium Abs: Mineralogical examination, using scanning electron microscopy (SEM), X-ray diffractometry (XRD), and optical microscopy, was conducted on the Fe0-bearing reactive materials derived from long-term column experiments undertaken to assess the treatment capacity of Fe0 under different geochemical conditions. The columns received either deionized water or solutions of differing dissolved calcium carbonate concentrations, together either with trichloroethene (TCE) or hexavalent chromium (Cr(VI)). The major reaction product in the columns receiving deionized water was magnetite-maghemite, and for the columns receiving dissolved calcium carbonate, the main products were iron hydroxy carbonate and aragonite. Replacement of Fe0 by reaction products occurred mainly at the edges of the Fe0 particles, and penetrative replacement was focused along cracks and along and around graphitic inclusions. Fibrous or flake-shaped iron hydroxy carbonate mostly replaced the edges of the Fe0 particles. Aragonite had needle-shaped morphology, and some occurred as clusters of crystals. Aragonite was deposited on iron hydroxy carbonate, thus providing at least a partial armoring effect. The mineral was also observed to cement groups of Fe0 particles into compact aggregates. The Cr was present mostly as Cr(III) in Cr(III)-Fe(III) (oxy)hydroxides and in trace amounts in iron hydroxy carbonate."
1231750,Yao et al. 2008,Microcalorimetric study the toxic effect of hexavalent chromium on microbial activity of Wuhan brown sandy soil: an in vitro approach,"A multi-channel thermal activity monitor was applied to study soil microbial activity in Wuhan brown sandy soil in the presence of different concentrations of hexavalent chromium (K(2)Cr(2)O(7)). In order to stimulate the soil microbial activity, 5.0mg of glucose and 5.0mg of ammonium sulfate were added to a 1.20-g soil sample under a controlled humidity of 35%. The results show that the poisonous species of K(2)Cr(2)O(7) at an half inhibitory concentration (IC(50)) value of 4.27 microg mL(-1) against soil microbe, and an increase of the amount of hexavalent chromium is associated to a decrease in the microbial activity of the soil, probably due to an increase in the toxicity of hexavalent chromium, affecting strongly the life in this soil microbial environment. Our work also suggests that microcalorimetry is a fast, simple and more sensitive method that can be easily performed to study the toxicity of different species of heavy metals on microorganism compared to other biological methods.","Microcalorimetric study the toxic effect of hexavalent chromium on microbial activity of Wuhan brown sandy soil: an in vitro approach Abs: A multi-channel thermal activity monitor was applied to study soil microbial activity in Wuhan brown sandy soil in the presence of different concentrations of hexavalent chromium (K(2)Cr(2)O(7)). In order to stimulate the soil microbial activity, 5.0mg of glucose and 5.0mg of ammonium sulfate were added to a 1.20-g soil sample under a controlled humidity of 35%. The results show that the poisonous species of K(2)Cr(2)O(7) at an half inhibitory concentration (IC(50)) value of 4.27 microg mL(-1) against soil microbe, and an increase of the amount of hexavalent chromium is associated to a decrease in the microbial activity of the soil, probably due to an increase in the toxicity of hexavalent chromium, affecting strongly the life in this soil microbial environment. Our work also suggests that microcalorimetry is a fast, simple and more sensitive method that can be easily performed to study the toxicity of different species of heavy metals on microorganism compared to other biological methods."
1231749,Cole 2007,Complying with OSHA's hexavalent chromium standards,,Complying with OSHA's hexavalent chromium standards Abs: 
1231748,Trahan and  Watters 2007,These problems aren't set in stone,,These problems aren't set in stone Abs: 
1231747,Graham and  Hu 2007,The risk-benefit balance in the United States: who decides?,"A health policy decision often requires a balancing of risks, costs, and benefits. In this paper we illustrate that there is no uniform answer in the United States to the question of who decides the risk-benefit balance. We use a wide range of case examples from medicine and public health to show the different approaches that are used to allocate decision-making responsibility. Our ultimate purpose is to urge the U.S. health policy community to develop a more consistent way of thinking about how risk-benefit decisions could be guided by general principles.","The risk-benefit balance in the United States: who decides? Abs: A health policy decision often requires a balancing of risks, costs, and benefits. In this paper we illustrate that there is no uniform answer in the United States to the question of who decides the risk-benefit balance. We use a wide range of case examples from medicine and public health to show the different approaches that are used to allocate decision-making responsibility. Our ultimate purpose is to urge the U.S. health policy community to develop a more consistent way of thinking about how risk-benefit decisions could be guided by general principles."
1231746,Lalaouni et al. 2007,The interaction of chromium (VI) with macrophages: depletion of glutathione and inhibition of glutathione reductase,"There are reports of alterations in the number and functions of the cells of the immune system in patients with metal-on-metal (MOM) orthopaedic implants. These effects have been correlated with elevated chromium levels in the patients' blood. We have investigated the interactions of clinically relevant concentrations of Cr VI with macrophages in vitro, and the mechanisms responsible for its toxicity. Cr VI causes a concentration dependent decrease in macrophage viability above 1 microM as measured by the MTT and Neutral Red assays. This falls well within the range of circulating chromium serum concentrations measured in patients with MOM. Intracellular reduced glutathione (GSH) levels fall as a result, and most of the loss (86%) is accounted for by oxidation to the dimer, GSSG. Prior depletion of GSH does not sensitise the cells to Cr VI toxicity, implying that it is not involved in protecting the cells against the effects of Cr VI. During the metabolism of Cr VI, glutathione reductase activity is inhibited. In contrast, the activities of catalase and superoxide dismutase are not significantly altered. Prior inhibition of glutathione reductase activity protects against the toxicity of Cr VI to a significant extent, suggesting that it reduces Cr VI to a toxic metabolite.","The interaction of chromium (VI) with macrophages: depletion of glutathione and inhibition of glutathione reductase Abs: There are reports of alterations in the number and functions of the cells of the immune system in patients with metal-on-metal (MOM) orthopaedic implants. These effects have been correlated with elevated chromium levels in the patients' blood. We have investigated the interactions of clinically relevant concentrations of Cr VI with macrophages in vitro, and the mechanisms responsible for its toxicity. Cr VI causes a concentration dependent decrease in macrophage viability above 1 microM as measured by the MTT and Neutral Red assays. This falls well within the range of circulating chromium serum concentrations measured in patients with MOM. Intracellular reduced glutathione (GSH) levels fall as a result, and most of the loss (86%) is accounted for by oxidation to the dimer, GSSG. Prior depletion of GSH does not sensitise the cells to Cr VI toxicity, implying that it is not involved in protecting the cells against the effects of Cr VI. During the metabolism of Cr VI, glutathione reductase activity is inhibited. In contrast, the activities of catalase and superoxide dismutase are not significantly altered. Prior inhibition of glutathione reductase activity protects against the toxicity of Cr VI to a significant extent, suggesting that it reduces Cr VI to a toxic metabolite."
1231745,Orozco et al. 2008,Modelling Cr(VI) removal by a combined carbon-activated sludge system,"The combined carbon-activated sludge process has been proposed as an alternative to protect the biomass against toxic substances in wastewaters; however, the information about the effect of powdered-activated carbon (PAC) addition in activated sludge reactors for the treatment of wastewaters containing Cr(VI) is limited. The objectives of the present study were: (a) to evaluate the removal of hexavalent chromium by (i) activated sludge microorganisms in aerobic batch reactors, (ii) powdered-activated carbon, and (iii) the combined action of powdered-activated carbon and biomass; (b) to propose mathematical models that interpret the experimental results. Different Cr(VI) removal systems were tested: (S1) biomass (activated sludge), (S2) PAC, and (S3) the combined activated carbon-biomass system. A Monod-based mathematical model was used to describe the kinetics of Cr(VI) removal in the system S1. A first-order kinetics with respect to Cr(VI) and PAC respectively, was proposed to model the removal of Cr(VI) in the system S2. Cr(VI) removal in the combined carbon-biomass system (S3) was faster than both Cr(VI) removal using PAC or activated sludge individually. Results showed that the removal of Cr(VI) using the activated carbon-biomass system (S3) was adequately described by combining the kinetic equations proposed for the systems S1 and S2.","Modelling Cr(VI) removal by a combined carbon-activated sludge system Abs: The combined carbon-activated sludge process has been proposed as an alternative to protect the biomass against toxic substances in wastewaters; however, the information about the effect of powdered-activated carbon (PAC) addition in activated sludge reactors for the treatment of wastewaters containing Cr(VI) is limited. The objectives of the present study were: (a) to evaluate the removal of hexavalent chromium by (i) activated sludge microorganisms in aerobic batch reactors, (ii) powdered-activated carbon, and (iii) the combined action of powdered-activated carbon and biomass; (b) to propose mathematical models that interpret the experimental results. Different Cr(VI) removal systems were tested: (S1) biomass (activated sludge), (S2) PAC, and (S3) the combined activated carbon-biomass system. A Monod-based mathematical model was used to describe the kinetics of Cr(VI) removal in the system S1. A first-order kinetics with respect to Cr(VI) and PAC respectively, was proposed to model the removal of Cr(VI) in the system S2. Cr(VI) removal in the combined carbon-biomass system (S3) was faster than both Cr(VI) removal using PAC or activated sludge individually. Results showed that the removal of Cr(VI) using the activated carbon-biomass system (S3) was adequately described by combining the kinetic equations proposed for the systems S1 and S2."
1231744,Aravindhan et al. 2007,Biological removal of carcinogenic chromium(VI) using mixed Pseudomonas strains,"The contamination of soil and wastewaters with Cr(VI) is a major problem. It has been suggested that microbial methods for Cr(VI) reduction are better than chemical methods, as they do not add other ions or toxic chemicals to the environment. In this study an aerobic reduction of Cr(VI) to Cr(III) by employing mixed Pseudomonas cultures isolated from a marshy land has been reported. The role of chromium concentration, temperature, pH and additives on the microbial reduction of Cr(VI) has been investigated. NADH was found to enhance the rate of reduction of Cr(VI). Complete reduction of chromium(VI) has been possible even at chromium(VI) concentrations of 300 ppm. Ions like SO(4)(2-) and poly-phenols inhibited the metabolic activity relating to Cr(VI) reduction. Under optimal conditions 100 mg/L of Cr(VI) was completely reduced within 180 min.","Biological removal of carcinogenic chromium(VI) using mixed Pseudomonas strains Abs: The contamination of soil and wastewaters with Cr(VI) is a major problem. It has been suggested that microbial methods for Cr(VI) reduction are better than chemical methods, as they do not add other ions or toxic chemicals to the environment. In this study an aerobic reduction of Cr(VI) to Cr(III) by employing mixed Pseudomonas cultures isolated from a marshy land has been reported. The role of chromium concentration, temperature, pH and additives on the microbial reduction of Cr(VI) has been investigated. NADH was found to enhance the rate of reduction of Cr(VI). Complete reduction of chromium(VI) has been possible even at chromium(VI) concentrations of 300 ppm. Ions like SO(4)(2-) and poly-phenols inhibited the metabolic activity relating to Cr(VI) reduction. Under optimal conditions 100 mg/L of Cr(VI) was completely reduced within 180 min."
1231743,Poljsak and  Raspor 2008,The antioxidant and pro-oxidant activity of vitamin C and trolox in vitro: a comparative study,"The antioxidant and pro-oxidant properties of ascorbic acid (vitamin C) and the water-soluble analogue of alpha-tocopherol (trolox) were compared. Trolox has advantages over alpha-tocopherol, the latter being only lipid-soluble due to the presence of a carboxyl group in lieu of a phytol chain which imparts trolox with water solubility. Trolox is used as a standard antioxidant in biochemical studies against which the antioxidant capacity of compounds is compared. Although ascorbic acid and tocopherols possess strong antioxidant properties, they might also exhibit pro-oxidant properties in the presence of free transition metals. Thus, reactions detailed in this study were performed in the presence of Cr(VI) in an effort to investigate the potential of ascorbic acid and trolox to generate hydroxyl radicals in a Fenton-like reaction. Results obtained were derived from reactions containing the same concentration of ascorbic acid and trolox under identical experimental conditions. Hydroxyl radical formation was observed in the reaction of Cr(VI) with ascorbic acid resulting from ascorbic acid auto-oxidation and H2O2 formation. Hydroxyl radical formation was only detected in the reaction mixture containing Cr(VI) and trolox following the addition of H2O2.","The antioxidant and pro-oxidant activity of vitamin C and trolox in vitro: a comparative study Abs: The antioxidant and pro-oxidant properties of ascorbic acid (vitamin C) and the water-soluble analogue of alpha-tocopherol (trolox) were compared. Trolox has advantages over alpha-tocopherol, the latter being only lipid-soluble due to the presence of a carboxyl group in lieu of a phytol chain which imparts trolox with water solubility. Trolox is used as a standard antioxidant in biochemical studies against which the antioxidant capacity of compounds is compared. Although ascorbic acid and tocopherols possess strong antioxidant properties, they might also exhibit pro-oxidant properties in the presence of free transition metals. Thus, reactions detailed in this study were performed in the presence of Cr(VI) in an effort to investigate the potential of ascorbic acid and trolox to generate hydroxyl radicals in a Fenton-like reaction. Results obtained were derived from reactions containing the same concentration of ascorbic acid and trolox under identical experimental conditions. Hydroxyl radical formation was observed in the reaction of Cr(VI) with ascorbic acid resulting from ascorbic acid auto-oxidation and H2O2 formation. Hydroxyl radical formation was only detected in the reaction mixture containing Cr(VI) and trolox following the addition of H2O2."
1231742,Güell et al. 2007,Development of a selective optical sensor for Cr(VI) monitoring in polluted waters,"An optical sensor is described for the sensitive and selective determination of the Cr(VI) ion in aqueous solutions. The optode membrane is prepared by incorporating Aliquat 336 as an ionophore and a chromoionophore (4',5'-dibromofluorescein octadecyl ester) in a poly(vinyl chloride) (PVC) membrane containing ortho-nitrophenyloctyl ether (o-NPOE) as a plasticizer. The response to Cr(VI) is indicated by co-extraction of the target species and of hydrogen ions into the bulk of the membrane yielding large absorbance changes which can easily be measured in the visible spectral range. The optode membrane shows a reversible response in the concentration range of 1.1x10(-5)-1.0x10(-3) M and has been shown to be more selective towards the HCrO4(-) ion than other anions with a selectivity pattern HCrO4(-) &gt; SCN- approximately = ClO4(-) &gt; NO3(-) approximately = I- approximately = NO2(-) &gt; H2PO4(-) approximately = Cl- approximately = SO4(2-). The sensing method developed has successfully been applied to the determination of Cr(VI) in spiked river water as well as in electroplating rinse waters.","Development of a selective optical sensor for Cr(VI) monitoring in polluted waters Abs: An optical sensor is described for the sensitive and selective determination of the Cr(VI) ion in aqueous solutions. The optode membrane is prepared by incorporating Aliquat 336 as an ionophore and a chromoionophore (4',5'-dibromofluorescein octadecyl ester) in a poly(vinyl chloride) (PVC) membrane containing ortho-nitrophenyloctyl ether (o-NPOE) as a plasticizer. The response to Cr(VI) is indicated by co-extraction of the target species and of hydrogen ions into the bulk of the membrane yielding large absorbance changes which can easily be measured in the visible spectral range. The optode membrane shows a reversible response in the concentration range of 1.1x10(-5)-1.0x10(-3) M and has been shown to be more selective towards the HCrO4(-) ion than other anions with a selectivity pattern HCrO4(-) &gt; SCN- approximately = ClO4(-) &gt; NO3(-) approximately = I- approximately = NO2(-) &gt; H2PO4(-) approximately = Cl- approximately = SO4(2-). The sensing method developed has successfully been applied to the determination of Cr(VI) in spiked river water as well as in electroplating rinse waters."
1231741,Rajesh et al. 2008,Solid phase extraction of chromium(VI) from aqueous solutions by adsorption of its diphenylcarbazide complex on an Amberlite XAD-4 resin column,"A method has been developed for the solid phase extraction of chromium(VI) based on the adsorption of its diphenylcarbazide complex on an Amberlite XAD-4 resin column. The influence of acidity, stability of the column, sample volume, flow rate and interfering ions were studied in detail. The adsorbed complex could be eluted using acetone-sulfuric acid mixture and the concentration of chromium was determined using visible spectrophotometry. A detection limit of 6 microg L(-1) could be achieved. A preconcentration factor of 27 could be obtained for 400 mL sample volume. The validity of the method was checked in spiked water samples and electroplating wastewater.","Solid phase extraction of chromium(VI) from aqueous solutions by adsorption of its diphenylcarbazide complex on an Amberlite XAD-4 resin column Abs: A method has been developed for the solid phase extraction of chromium(VI) based on the adsorption of its diphenylcarbazide complex on an Amberlite XAD-4 resin column. The influence of acidity, stability of the column, sample volume, flow rate and interfering ions were studied in detail. The adsorbed complex could be eluted using acetone-sulfuric acid mixture and the concentration of chromium was determined using visible spectrophotometry. A detection limit of 6 microg L(-1) could be achieved. A preconcentration factor of 27 could be obtained for 400 mL sample volume. The validity of the method was checked in spiked water samples and electroplating wastewater."
1231740,Tirez et al. 2007,Validation of a European standard for the determination of hexavalent chromium in solid material,"A European standard for the determination of Cr(vi) in solid material has been elaborated in the framework of an international co-operation and finally validated in the course of an interlaboratory comparison. The procedure is based on the alkaline digestion prescribed by EPA method 3060A followed by ion chromatography and determines an operationally defined content of Cr(vi), including water-soluble and insoluble chromates. A preliminary robustness study was carried out in order to compare different extraction methodologies and to study the equivalency of different analytical methods for the determination of Cr(vi) in alkaline extracts of soil and waste materials. During an interlaboratory validation trial with 19 European laboratories a set of 4 samples (2 soil and 2 waste samples) was analysed to determine performance characteristics for different combinations of digestion and detection methods. With the procedures prescribed by the new European standard (EN 15192) acceptable results were obtained for both soil samples and one of the waste samples (sludge). However, for the second waste sample (fly ash) a large deviation in analytical results was observed. This indicates that particularly for waste materials a possible occurrence of strong matrix effects has to be considered and supplementary quality control data are needed in order to assess the validity of analytical results. The accuracy of the determination of Cr(vi) in solid matrices remains a challenging field in terms of maximum extraction efficiency and minimum species interconversion.","Validation of a European standard for the determination of hexavalent chromium in solid material Abs: A European standard for the determination of Cr(vi) in solid material has been elaborated in the framework of an international co-operation and finally validated in the course of an interlaboratory comparison. The procedure is based on the alkaline digestion prescribed by EPA method 3060A followed by ion chromatography and determines an operationally defined content of Cr(vi), including water-soluble and insoluble chromates. A preliminary robustness study was carried out in order to compare different extraction methodologies and to study the equivalency of different analytical methods for the determination of Cr(vi) in alkaline extracts of soil and waste materials. During an interlaboratory validation trial with 19 European laboratories a set of 4 samples (2 soil and 2 waste samples) was analysed to determine performance characteristics for different combinations of digestion and detection methods. With the procedures prescribed by the new European standard (EN 15192) acceptable results were obtained for both soil samples and one of the waste samples (sludge). However, for the second waste sample (fly ash) a large deviation in analytical results was observed. This indicates that particularly for waste materials a possible occurrence of strong matrix effects has to be considered and supplementary quality control data are needed in order to assess the validity of analytical results. The accuracy of the determination of Cr(vi) in solid matrices remains a challenging field in terms of maximum extraction efficiency and minimum species interconversion."
1231739,Shelnutt et al. 2007,Dermatological toxicity of hexavalent chromium,"Hexavalent chromium causes two types of dermatological toxicities: allergic contact dermatitis (ACD) and skin ulcers. This report reviews the etiology, prevalence, pathology, dose-response, and prognosis of both of these reactions. Reports in the literature indicate that repeated exposure to hexavalent chromium in concentrations of 4-25 ppm can both induce sensitization and elicit chromium ACD. Exposure to 20 ppm hexavalent chromium can cause skin ulcers in nonsensitized people. The prevalence of chromium sensitivity in cement workers, exposed to 10-20 ppm hexavalent chromium for years, is approximately 4-5%. Chromium ACD can be a chronic debilitating disease, perhaps because chromium is ubiquitous in foods and in the environment and is difficult to avoid. Due to the high rates of sensitization in populations chronically exposed to chromium and the chronic nature of chromium ACD, some investigators recommend reducing the hexavalent chromiumconcentrations in consumer products, such as detergents, to less than 5 ppm.","Dermatological toxicity of hexavalent chromium Abs: Hexavalent chromium causes two types of dermatological toxicities: allergic contact dermatitis (ACD) and skin ulcers. This report reviews the etiology, prevalence, pathology, dose-response, and prognosis of both of these reactions. Reports in the literature indicate that repeated exposure to hexavalent chromium in concentrations of 4-25 ppm can both induce sensitization and elicit chromium ACD. Exposure to 20 ppm hexavalent chromium can cause skin ulcers in nonsensitized people. The prevalence of chromium sensitivity in cement workers, exposed to 10-20 ppm hexavalent chromium for years, is approximately 4-5%. Chromium ACD can be a chronic debilitating disease, perhaps because chromium is ubiquitous in foods and in the environment and is difficult to avoid. Due to the high rates of sensitization in populations chronically exposed to chromium and the chronic nature of chromium ACD, some investigators recommend reducing the hexavalent chromiumconcentrations in consumer products, such as detergents, to less than 5 ppm."
1231738,Sun et al. 2007,Preparation of activated carbon with large specific surface area from reed black liquor,"Activated carbon with large specific surface area and well-developed porosity was prepared from pyrolysis of K2CO3-impregnated lignin precipitated from reed pulp black liquors. The impregnation ratio was 1:1. The effect of activation temperature upon the Brunauer-Emmett-Teller (BET) specific surface area and pore volume of the carbon was closely investigated. Increasing activation temperature led to an opening and widening of the porous structure below 800'C. Above 800'C, the excess widening of pore led to the decrease of BET surface area and micropore volume. The BET surface area and pore volume of the carbon activated at 800 degrees C were 1395 m(2) g(-1) and 0.7702 ml g(-1) , respectively. The potential application of the carbon activated at 800 degrees C for removal of Cr (VI) was also investigated. The experimental results showed that it had good adsorption capacity.","Preparation of activated carbon with large specific surface area from reed black liquor Abs: Activated carbon with large specific surface area and well-developed porosity was prepared from pyrolysis of K2CO3-impregnated lignin precipitated from reed pulp black liquors. The impregnation ratio was 1:1. The effect of activation temperature upon the Brunauer-Emmett-Teller (BET) specific surface area and pore volume of the carbon was closely investigated. Increasing activation temperature led to an opening and widening of the porous structure below 800'C. Above 800'C, the excess widening of pore led to the decrease of BET surface area and micropore volume. The BET surface area and pore volume of the carbon activated at 800 degrees C were 1395 m(2) g(-1) and 0.7702 ml g(-1) , respectively. The potential application of the carbon activated at 800 degrees C for removal of Cr (VI) was also investigated. The experimental results showed that it had good adsorption capacity."
1231736,Svecevicius 2007,Avoidance response of rainbow trout Oncorhynchus mykiss to hexavalent chromium solutions,"Laboratory tests were conducted on one-year-old rainbow trout Oncorhynchus mykiss to evaluate their ability to detect and avoid hexavalent chromium (Cr(6+)). Test fish were given a choice to discriminate between clean water and Cr(6+) solutions of six sublethal concentrations ranging from 0.0015 to 0.3 mg Cr/L in a counter-current flow, steep gradient chamber. The intensity of avoidance response reached a significant level at test concentrations of 0.003 mg Cr/L and higher, and was directly proportional to the Cr(6+) concentration logarithm. Avoidance threshold was estimated through regression analysis and to be 0.0017 mg Cr/L. This result is approximately sixfold lower than maximum-permitted concentration of 0.01 mg Cr/L accepted as the Lithuanian water-quality guideline for the protection of aquatic life.","Avoidance response of rainbow trout Oncorhynchus mykiss to hexavalent chromium solutions Abs: Laboratory tests were conducted on one-year-old rainbow trout Oncorhynchus mykiss to evaluate their ability to detect and avoid hexavalent chromium (Cr(6+)). Test fish were given a choice to discriminate between clean water and Cr(6+) solutions of six sublethal concentrations ranging from 0.0015 to 0.3 mg Cr/L in a counter-current flow, steep gradient chamber. The intensity of avoidance response reached a significant level at test concentrations of 0.003 mg Cr/L and higher, and was directly proportional to the Cr(6+) concentration logarithm. Avoidance threshold was estimated through regression analysis and to be 0.0017 mg Cr/L. This result is approximately sixfold lower than maximum-permitted concentration of 0.01 mg Cr/L accepted as the Lithuanian water-quality guideline for the protection of aquatic life."
1231735,Park et al. 2007,Reliable evidences that the removal mechanism of hexavalent chromium by natural biomaterials is adsorption-coupled reduction,"For the last few decades, over 200 papers have been published in the Cr(VI) biosorption research field. Most early studies have claimed that Cr(VI) was removed from aqueous phase through an anionic adsorption, but this approach has been lost old original position. It has been newly explained that these findings were misinterpreted due to errors in measuring the concentrations of different chromium species in the aqueous phase, insufficient contact time required for equilibrium and the lack of information about the oxidation state of the chromium bound to biomaterials. Although 'adsorption-coupled reduction' is now widely accepted as the mechanism of Cr(VI) biosorption by natural biomaterials, a number of researchers still believe that Cr(VI) is removed by anionic adsorption onto the biomaterials. Therefore, the objective of this study was to show reliable evidences that the removal mechanism of Cr(VI) by natural biomaterials is 'adsorption-coupled reduction'. Sixteen natural biomaterials were used to study the Cr(VI) biosorption. Not only Cr(VI) but also total Cr in the aqueous phase were analyzed. X-ray photoelectron spectroscope was also used to verify the oxidation state of the chromium bound to the biomaterials. Finally, the removal behavior of Cr(VI) by each biomaterial was described by a kinetic model based on a redox reaction.","Reliable evidences that the removal mechanism of hexavalent chromium by natural biomaterials is adsorption-coupled reduction Abs: For the last few decades, over 200 papers have been published in the Cr(VI) biosorption research field. Most early studies have claimed that Cr(VI) was removed from aqueous phase through an anionic adsorption, but this approach has been lost old original position. It has been newly explained that these findings were misinterpreted due to errors in measuring the concentrations of different chromium species in the aqueous phase, insufficient contact time required for equilibrium and the lack of information about the oxidation state of the chromium bound to biomaterials. Although 'adsorption-coupled reduction' is now widely accepted as the mechanism of Cr(VI) biosorption by natural biomaterials, a number of researchers still believe that Cr(VI) is removed by anionic adsorption onto the biomaterials. Therefore, the objective of this study was to show reliable evidences that the removal mechanism of Cr(VI) by natural biomaterials is 'adsorption-coupled reduction'. Sixteen natural biomaterials were used to study the Cr(VI) biosorption. Not only Cr(VI) but also total Cr in the aqueous phase were analyzed. X-ray photoelectron spectroscope was also used to verify the oxidation state of the chromium bound to the biomaterials. Finally, the removal behavior of Cr(VI) by each biomaterial was described by a kinetic model based on a redox reaction."
1231734,Figueiredo et al. 2007,Validation of an electrothermal atomization atomic absorption spectrometry method for quantification of total chromium and chromium(VI) in wild mushrooms and underlying soils,"An ETAAS method was validated to quantify total Cr and Cr(VI) in mushrooms and the underlying soils. The method includes a sample pretreatment for total Cr dissolution using a wet acid digestion procedure and a selective alkaline extraction for Cr(VI). The limits of detection were, expressed in microg/L, 0.15 and 0.17 for total Cr and Cr(VI), respectively. The linearity ranges under the optimized conditions were 0.15-25.0 and 0.17-20.0 microg/L for total Cr and Cr(VI), respectively. The limits of quantification were, expressed in microg/g of dry weight, 0.0163 and 0.0085 for total and hexavalent chromium, respectively. The precision of the instrumental method for total Cr and Cr(VI) was lower than 1.6%, and for the analytical method, it was lower than 10%. The accuracy of the method for Cr(VI) quantification was evaluated by the standard additions method, with the recoveries being higher than 90% for all of the added concentrations. For total Cr, certified reference materials (lichen CRM 482 and soil sample NCS ZC73001) were used. An interference study was also carried out in a mushroom simulated matrix, and it was verified that the deviations of the expected values were lower than 4.0% for both total Cr and Cr(VI). The validated method was applied to the evaluation of total Cr and Cr(VI) in 34 wild mushrooms and 34 respective underlying soil samples collected in two different regions of Portugal (Beira Interior and TrAs-os-Montes), with different locations regarded as noncontaminated or contaminated areas. The species were identified by a mycologist and subdivided into 10 genera and 15 species: Amanita (rubescens, muscaria, and ponderosa), Boletus (regius), Lactarius (deliciosus, vellereus, and piperatus), Suillus (granulatus and luteus), Tricholoma (acerbum), Agaricus (sylvicola), Volvariella (gloiocephala), Lecopaxillus (giganteus), Macrolepiota (procera), and Psilocybe (fascicularis). The mean values found for total Cr were 1.14 and 1.11 microg/g of dry weight, and for Cr(VI), the mean values were 0.103 and 0.143 microg/g of dry weight for cap and stalk, respectively. For soils, the mean concentrations found were, for total Cr, 84.0 microg/g and, for Cr(VI), 0.483 microg/g. The bioconcentration factors (BCFs) based on dry weight for cap and stalk were determined, and the values found, for both total Cr and Cr(VI), were always &lt;1, although for hexavalent chromium, the BCFs were 10 times higher than for total chromium.","Validation of an electrothermal atomization atomic absorption spectrometry method for quantification of total chromium and chromium(VI) in wild mushrooms and underlying soils Abs: An ETAAS method was validated to quantify total Cr and Cr(VI) in mushrooms and the underlying soils. The method includes a sample pretreatment for total Cr dissolution using a wet acid digestion procedure and a selective alkaline extraction for Cr(VI). The limits of detection were, expressed in microg/L, 0.15 and 0.17 for total Cr and Cr(VI), respectively. The linearity ranges under the optimized conditions were 0.15-25.0 and 0.17-20.0 microg/L for total Cr and Cr(VI), respectively. The limits of quantification were, expressed in microg/g of dry weight, 0.0163 and 0.0085 for total and hexavalent chromium, respectively. The precision of the instrumental method for total Cr and Cr(VI) was lower than 1.6%, and for the analytical method, it was lower than 10%. The accuracy of the method for Cr(VI) quantification was evaluated by the standard additions method, with the recoveries being higher than 90% for all of the added concentrations. For total Cr, certified reference materials (lichen CRM 482 and soil sample NCS ZC73001) were used. An interference study was also carried out in a mushroom simulated matrix, and it was verified that the deviations of the expected values were lower than 4.0% for both total Cr and Cr(VI). The validated method was applied to the evaluation of total Cr and Cr(VI) in 34 wild mushrooms and 34 respective underlying soil samples collected in two different regions of Portugal (Beira Interior and TrAs-os-Montes), with different locations regarded as noncontaminated or contaminated areas. The species were identified by a mycologist and subdivided into 10 genera and 15 species: Amanita (rubescens, muscaria, and ponderosa), Boletus (regius), Lactarius (deliciosus, vellereus, and piperatus), Suillus (granulatus and luteus), Tricholoma (acerbum), Agaricus (sylvicola), Volvariella (gloiocephala), Lecopaxillus (giganteus), Macrolepiota (procera), and Psilocybe (fascicularis). The mean values found for total Cr were 1.14 and 1.11 microg/g of dry weight, and for Cr(VI), the mean values were 0.103 and 0.143 microg/g of dry weight for cap and stalk, respectively. For soils, the mean concentrations found were, for total Cr, 84.0 microg/g and, for Cr(VI), 0.483 microg/g. The bioconcentration factors (BCFs) based on dry weight for cap and stalk were determined, and the values found, for both total Cr and Cr(VI), were always &lt;1, although for hexavalent chromium, the BCFs were 10 times higher than for total chromium."
1231733,Dutta et al. 2007,Modulatory effect of distillate of Ocimum sanctum leaf extract (Tulsi) on human lymphocytes against genotoxicants,"<strong>OBJECTIVE: </strong>To study the modulatory effect of distillate of Ocimum sanctum (traditionally known as Tulsi) leaf extract (DTLE) on genotoxicants.<br /><br /><strong>METHODS: </strong>In the present investigation, we studied the antigenotoxic and anticlastogenic effect of distillate of Tulsi leaf extract on (i) human polymorphonuclear leukocytes by evaluating the DNA strand break without metabolic activation against mitomycin C (MMC) and hexavalent chromium (Cr+6) and (ii) human peripheral lymphocytes (in vitro) with or without metabolic activation against mitomycin C (MMC), hexavalent chromium (Cr+6) and B[a]P by evaluating chromosomal aberration (CA) and micronucleus assay (MN). Three different doses of DTLE, 50 microL/mL, 100 microL/mL, and 200 microL/mL were selected on the basis of cytotoxicity assay and used for studying DNA strand break, chromosomal aberration and micronucleus emergence. The following positive controls were used for inducing genotoxicity and clastogenicity: MMC (0.29 micromol/L) for DNA strand break, chromosomal aberration and 0.51 micromol/L for micronucleus assay; Potassium dichromate (Cr+6) 600 micromol/L for DNA strand break and 5 micromol/L for chromosomal aberration and micronucleus assay; Benzo[a]pyrene (30 micromol/L) for chromosomal aberration and 40 micromol/L for micronucleus assay. The active ingredients present in the distillate of Tulsi leaf extract were identified by HPLC and LC-MS.<br /><br /><strong>RESULTS: </strong>Mitomycin C (MMC) and hexavalent chromium (Cr+6) induced statistically significant DNA strand break of respectively 69% and 71% (P&lt;0.001) as revealed by fluorometric analysis of DNA unwinding. Furthermore, the damage could be protected with DTLE (50 microL/mL, 100 microL/mL, and 200 microL/mL) on simultaneous treatment. Chromosomal aberration and micronucleus formation induced by MMC, Cr+6 and B[a]P were significantly protected (P&lt;0.001) by DTLE with and without metabolic activation.<br /><br /><strong>CONCLUSION: </strong>Distillate of Tulsi leaf extract possesses antioxidants contributed mainly by eugenol, luteolin and apigenin as identified by LC-MS. These active ingredients may have the protective effect against genotoxicants.","Modulatory effect of distillate of Ocimum sanctum leaf extract (Tulsi) on human lymphocytes against genotoxicants Abs: <strong>OBJECTIVE: </strong>To study the modulatory effect of distillate of Ocimum sanctum (traditionally known as Tulsi) leaf extract (DTLE) on genotoxicants.<br /><br /><strong>METHODS: </strong>In the present investigation, we studied the antigenotoxic and anticlastogenic effect of distillate of Tulsi leaf extract on (i) human polymorphonuclear leukocytes by evaluating the DNA strand break without metabolic activation against mitomycin C (MMC) and hexavalent chromium (Cr+6) and (ii) human peripheral lymphocytes (in vitro) with or without metabolic activation against mitomycin C (MMC), hexavalent chromium (Cr+6) and B[a]P by evaluating chromosomal aberration (CA) and micronucleus assay (MN). Three different doses of DTLE, 50 microL/mL, 100 microL/mL, and 200 microL/mL were selected on the basis of cytotoxicity assay and used for studying DNA strand break, chromosomal aberration and micronucleus emergence. The following positive controls were used for inducing genotoxicity and clastogenicity: MMC (0.29 micromol/L) for DNA strand break, chromosomal aberration and 0.51 micromol/L for micronucleus assay; Potassium dichromate (Cr+6) 600 micromol/L for DNA strand break and 5 micromol/L for chromosomal aberration and micronucleus assay; Benzo[a]pyrene (30 micromol/L) for chromosomal aberration and 40 micromol/L for micronucleus assay. The active ingredients present in the distillate of Tulsi leaf extract were identified by HPLC and LC-MS.<br /><br /><strong>RESULTS: </strong>Mitomycin C (MMC) and hexavalent chromium (Cr+6) induced statistically significant DNA strand break of respectively 69% and 71% (P&lt;0.001) as revealed by fluorometric analysis of DNA unwinding. Furthermore, the damage could be protected with DTLE (50 microL/mL, 100 microL/mL, and 200 microL/mL) on simultaneous treatment. Chromosomal aberration and micronucleus formation induced by MMC, Cr+6 and B[a]P were significantly protected (P&lt;0.001) by DTLE with and without metabolic activation.<br /><br /><strong>CONCLUSION: </strong>Distillate of Tulsi leaf extract possesses antioxidants contributed mainly by eugenol, luteolin and apigenin as identified by LC-MS. These active ingredients may have the protective effect against genotoxicants."
1231732,Martínez-Jerónimo and  Muñoz-Mejía 2007,Evaluation of the sensitivity of three cladoceran species widely distributed in Mexico to three reference toxicants,"Acute toxicity effects of sodium dodecyl sulfate (SDS), sodium pentachlorophenate (SPCP), and hexavalent chromium (Cr(VI)) were determined in Ceriodaphnia dubia, Daphnia pulex, and Simocephalus mixtus. Neonates were obtained from parthenogenetic females of different ages to establish the relative sensitivity of these species, in order to propose them as test organisms in the Mexican environmental standards. For C. dubia the average LC(50) (48 h) values were 8.59 +/- 1.08, 0.92 +/- 0.16, and 0.23 +/- 0.04; for D. pulex, 5.34 +/- 0.90, 1.49 +/- 0.29, and 0.28 +/- 0.06; whereas for S. mixtus, they were 4.50 +/- 0.41, 1.31 +/- 0.16, and 0.12 +/- 0.03 mg/L for SDS, SPCP, and Cr(VI), respectively. SDS and SPCP acute toxicity results depicted coefficients of variation of &lt;or= 40 % that were not related to the age of mothers. The same was observed for Cr(VI) with C. dubia, whereas for S. mixtus and D. pulex a reduction in neonates' sensitivity was determined for progeny produced by females older than 23 and 25 days, respectively; this situation establishes limits to the useful period of the culture for the supply of test organisms from these cladocerans. The less toxic reference toxicant was SDS. S. mixtus was the most sensitive cladoceran to SDS and Cr(VI), whereas C. dubia was the most sensitive to SPCP. Although differences existed in the culture conditions and in managing the production of newborns, results suggest the feasibility of using D. pulex and S. mixtus as test organisms in acute toxicity assessment as surrogates of D. magna, an exotic cladoceran in Mexico. Considering its short life-cycle, C. dubia could be used in chronic toxicity tests, as well as in acute toxicity tests, having in both situations the advantage of requiring lower volumes of test samples.","Evaluation of the sensitivity of three cladoceran species widely distributed in Mexico to three reference toxicants Abs: Acute toxicity effects of sodium dodecyl sulfate (SDS), sodium pentachlorophenate (SPCP), and hexavalent chromium (Cr(VI)) were determined in Ceriodaphnia dubia, Daphnia pulex, and Simocephalus mixtus. Neonates were obtained from parthenogenetic females of different ages to establish the relative sensitivity of these species, in order to propose them as test organisms in the Mexican environmental standards. For C. dubia the average LC(50) (48 h) values were 8.59 +/- 1.08, 0.92 +/- 0.16, and 0.23 +/- 0.04; for D. pulex, 5.34 +/- 0.90, 1.49 +/- 0.29, and 0.28 +/- 0.06; whereas for S. mixtus, they were 4.50 +/- 0.41, 1.31 +/- 0.16, and 0.12 +/- 0.03 mg/L for SDS, SPCP, and Cr(VI), respectively. SDS and SPCP acute toxicity results depicted coefficients of variation of &lt;or= 40 % that were not related to the age of mothers. The same was observed for Cr(VI) with C. dubia, whereas for S. mixtus and D. pulex a reduction in neonates' sensitivity was determined for progeny produced by females older than 23 and 25 days, respectively; this situation establishes limits to the useful period of the culture for the supply of test organisms from these cladocerans. The less toxic reference toxicant was SDS. S. mixtus was the most sensitive cladoceran to SDS and Cr(VI), whereas C. dubia was the most sensitive to SPCP. Although differences existed in the culture conditions and in managing the production of newborns, results suggest the feasibility of using D. pulex and S. mixtus as test organisms in acute toxicity assessment as surrogates of D. magna, an exotic cladoceran in Mexico. Considering its short life-cycle, C. dubia could be used in chronic toxicity tests, as well as in acute toxicity tests, having in both situations the advantage of requiring lower volumes of test samples."
1231731,Muñoz-Mejía et al. 2007,Comparative analysis between native and reference cladocerans to assess the toxic effects of products used by the oil industry in Mexico,"In this study, native cladocerans, Scapholeberis armata freyi and Macrothrix elegans, were collected from the region and their offspring were used as test organisms to assess the effects of 18 corrosion and scale inhibitors, widely used to protect oil pipelines. Daphnia magna and Ceriodaphnia dubia were used as international reference species, and their sensitivity was compared to native species and assessed with the reference toxicant Cr(VI). We also determined the correlation between the native and the reference species. Corrosion inhibitors were grouped according to their uses and acute toxicity gradient; those used for multifunction pipelines are considered moderately toxic (LC(50) of 10 to 100 mg/L), and the remainder as toxic (LC(50) between 1.0 and 10 mg/L). Scale inhibitors are considered non-toxic, since the LC(50) for the 4 species exceeded 2,000 mg/L. Sensitivity test to Cr(VI) indicated that M. elegans was the least sensitive species. There was a high correlation (&gt; 90%) in sensitivity among M. elegans, D. magna, and C. dubia to the corrosion inhibitors used. Hence, it is feasible to use these native species from Southeast Mexico as substitutes of the typical reference species.","Comparative analysis between native and reference cladocerans to assess the toxic effects of products used by the oil industry in Mexico Abs: In this study, native cladocerans, Scapholeberis armata freyi and Macrothrix elegans, were collected from the region and their offspring were used as test organisms to assess the effects of 18 corrosion and scale inhibitors, widely used to protect oil pipelines. Daphnia magna and Ceriodaphnia dubia were used as international reference species, and their sensitivity was compared to native species and assessed with the reference toxicant Cr(VI). We also determined the correlation between the native and the reference species. Corrosion inhibitors were grouped according to their uses and acute toxicity gradient; those used for multifunction pipelines are considered moderately toxic (LC(50) of 10 to 100 mg/L), and the remainder as toxic (LC(50) between 1.0 and 10 mg/L). Scale inhibitors are considered non-toxic, since the LC(50) for the 4 species exceeded 2,000 mg/L. Sensitivity test to Cr(VI) indicated that M. elegans was the least sensitive species. There was a high correlation (&gt; 90%) in sensitivity among M. elegans, D. magna, and C. dubia to the corrosion inhibitors used. Hence, it is feasible to use these native species from Southeast Mexico as substitutes of the typical reference species."
1231730,Weerasinghe et al. 2008,Phyto-remediation potential of Ipomoea aquatica for Cr(VI) mitigation,"Phyto-remedial efficiency of Ipomoea aquatica was examined at different experimental conditions for a period of 3 months. This plant was selected due to its easy establishment, tolerance and growing easiness. In all trials, the I. aquatica was grown in coir dust to ensure an inert medium. Essential growth nutrients were supplied externally using Albert solution. Once plant growth conditions were fixed, the model system was spiked with Cr(VI) solution in the range of 7-90 ppm. Up to 28 ppm Cr(VI), I. aquatica exhibits uniform absorption characteristics showing over 75% removal of added Cr(VI). At this stage I. aquatica was not affected and it showed no toxicity symptoms. Therefore, it is suited as a potential phyto-remediant. Further I. aquatica is a vegetable particularly in Asian region; therefore caution has to be taken when selecting it for human consumption due to its high chromium accumulation capacity.","Phyto-remediation potential of Ipomoea aquatica for Cr(VI) mitigation Abs: Phyto-remedial efficiency of Ipomoea aquatica was examined at different experimental conditions for a period of 3 months. This plant was selected due to its easy establishment, tolerance and growing easiness. In all trials, the I. aquatica was grown in coir dust to ensure an inert medium. Essential growth nutrients were supplied externally using Albert solution. Once plant growth conditions were fixed, the model system was spiked with Cr(VI) solution in the range of 7-90 ppm. Up to 28 ppm Cr(VI), I. aquatica exhibits uniform absorption characteristics showing over 75% removal of added Cr(VI). At this stage I. aquatica was not affected and it showed no toxicity symptoms. Therefore, it is suited as a potential phyto-remediant. Further I. aquatica is a vegetable particularly in Asian region; therefore caution has to be taken when selecting it for human consumption due to its high chromium accumulation capacity."
1231728,Xu et al. 2007,Photocatalytic reduction of hexavalent chromium and degradation of di-n-butyl phthalate in aqueous TiO2 suspensions under ultraviolet light irradiation,"Simultaneous photocatalytic reduction of chromium(VI) to the less toxic Cr(III) and degradation of di-n-butyl phthalate (DBP) in aqueous TiO2, suspension under ultraviolet light irradiation was investigated. The batch experiments were carried out in a photoreactor equipped with 350 nm lamps. The system containing Cr(VI) and DBP showed the synergistic photocatalytic decontamination as DBP facilitated Cr(VI) reduction, whereas Cr(VI) accelerated DBP degradation. This study demonstrated for the first time that two important environmental pollutants Cr(VI) and DBP could be eliminated simultaneously using UV/TiO2 process. The intermediate products of DBP degradation were identified by gas chromatography-mass spectrometry, and the reaction mechanism was proposed.","Photocatalytic reduction of hexavalent chromium and degradation of di-n-butyl phthalate in aqueous TiO2 suspensions under ultraviolet light irradiation Abs: Simultaneous photocatalytic reduction of chromium(VI) to the less toxic Cr(III) and degradation of di-n-butyl phthalate (DBP) in aqueous TiO2, suspension under ultraviolet light irradiation was investigated. The batch experiments were carried out in a photoreactor equipped with 350 nm lamps. The system containing Cr(VI) and DBP showed the synergistic photocatalytic decontamination as DBP facilitated Cr(VI) reduction, whereas Cr(VI) accelerated DBP degradation. This study demonstrated for the first time that two important environmental pollutants Cr(VI) and DBP could be eliminated simultaneously using UV/TiO2 process. The intermediate products of DBP degradation were identified by gas chromatography-mass spectrometry, and the reaction mechanism was proposed."
1231726,Costa et al. 2008,Electrochemical treatment of tannery wastewater using DSA electrodes,"In this work we studied the electrochemical treatment of a tannery wastewater using dimensionally stable anodes (DSA) containing tin, iridium, ruthenium, and titanium. The electrodes were prepared by thermal decomposition of the polymeric precursors. The electrolyses were performed under galvanostatic conditions, at room temperature. Effects of the oxide composition, current density, and effluent conductivity were investigated, and the current efficiency was calculated as a function of the time for the performed electrolyses. Results showed that all the studied electrodes led to a decrease in the content of both total phenolic compounds and total organic carbon (TOC), as well as lower absorbance in the UV-vis region. Toxicity tests using Daphnia similis demonstrated that the electrochemical treatment reduced the wastewater toxicity. The use of DSA type electrodes in the electrochemical treatment of tannery wastewater proved to be useful since it can promote a decrease in total phenolic compounds, TOC, absorbance, and toxicity.","Electrochemical treatment of tannery wastewater using DSA electrodes Abs: In this work we studied the electrochemical treatment of a tannery wastewater using dimensionally stable anodes (DSA) containing tin, iridium, ruthenium, and titanium. The electrodes were prepared by thermal decomposition of the polymeric precursors. The electrolyses were performed under galvanostatic conditions, at room temperature. Effects of the oxide composition, current density, and effluent conductivity were investigated, and the current efficiency was calculated as a function of the time for the performed electrolyses. Results showed that all the studied electrodes led to a decrease in the content of both total phenolic compounds and total organic carbon (TOC), as well as lower absorbance in the UV-vis region. Toxicity tests using Daphnia similis demonstrated that the electrochemical treatment reduced the wastewater toxicity. The use of DSA type electrodes in the electrochemical treatment of tannery wastewater proved to be useful since it can promote a decrease in total phenolic compounds, TOC, absorbance, and toxicity."
1231724,Saygi et al. 2008,Chromium speciation by solid phase extraction on Dowex M 4195 chelating resin and determination by atomic absorption spectrometry,"A solid phase extraction procedure has been established for chromium speciation in natural water samples prior to determination by atomic absorption spectrometry. The procedure is based on the solid phase extraction of the Cr(VI)- Dowex M 4195 chelating resin. After oxidation of Cr(III) to Cr(VI) by using H2O2, the presented method was applied to the determination of the total chromium. The level of Cr(III) is calculated by difference of total chromium and Cr(VI) levels. The procedure was optimized for some analytical parameters including pH, eluent type, flow rates of sample and eluent, matrix effects, etc. The presented method was applied for the speciation of chromium in natural water samples with satisfactory results (recoveries &gt;95%, RSDs &lt;10%). In the determinations of chromium species, flame atomic absorption spectrometer was used. The results were checked by using NIST SRM 2711 Montana soil and GBW 07603 Bush branched and leaves.","Chromium speciation by solid phase extraction on Dowex M 4195 chelating resin and determination by atomic absorption spectrometry Abs: A solid phase extraction procedure has been established for chromium speciation in natural water samples prior to determination by atomic absorption spectrometry. The procedure is based on the solid phase extraction of the Cr(VI)- Dowex M 4195 chelating resin. After oxidation of Cr(III) to Cr(VI) by using H2O2, the presented method was applied to the determination of the total chromium. The level of Cr(III) is calculated by difference of total chromium and Cr(VI) levels. The procedure was optimized for some analytical parameters including pH, eluent type, flow rates of sample and eluent, matrix effects, etc. The presented method was applied for the speciation of chromium in natural water samples with satisfactory results (recoveries &gt;95%, RSDs &lt;10%). In the determinations of chromium species, flame atomic absorption spectrometer was used. The results were checked by using NIST SRM 2711 Montana soil and GBW 07603 Bush branched and leaves."
1231723,Puzon et al. 2008,Mobility and recalcitrance of organo-chromium(III) complexes,"Hexavalent chromium [Cr(VI)] is a major industrial pollutant. Bioremediation of Cr(VI) to Cr(III) is a viable clean-up approach. However, Cr(VI) bioreduction also produces soluble organo-Cr(III) complexes, and little is known about their behavior in the environment. When tested with soil columns, citrate-Cr(III) showed little sorption to soil; malate-Cr(III) had limited partitioning with soil; and histidine-Cr(III) exhibited significant interaction with soil. It appears that the mobility varies depending on the organic ligand. Further, Ralstonia eutropha JMP 134 and Pseudomonas aeruginosa pAO1 readily degraded malate, citrate, and histidine, but not the corresponding organo-Cr(III) complexes. The recalcitrance is not due to toxicity, but the complexes are likely to cause hindrance to enzymes, as malate dehydrogenase and amino acid oxidase could not use malate-Cr(III) and histidine-Cr(III), respectively. The data are in agreement with the reports of soluble organo-Cr(III) complexes in the environment.","Mobility and recalcitrance of organo-chromium(III) complexes Abs: Hexavalent chromium [Cr(VI)] is a major industrial pollutant. Bioremediation of Cr(VI) to Cr(III) is a viable clean-up approach. However, Cr(VI) bioreduction also produces soluble organo-Cr(III) complexes, and little is known about their behavior in the environment. When tested with soil columns, citrate-Cr(III) showed little sorption to soil; malate-Cr(III) had limited partitioning with soil; and histidine-Cr(III) exhibited significant interaction with soil. It appears that the mobility varies depending on the organic ligand. Further, Ralstonia eutropha JMP 134 and Pseudomonas aeruginosa pAO1 readily degraded malate, citrate, and histidine, but not the corresponding organo-Cr(III) complexes. The recalcitrance is not due to toxicity, but the complexes are likely to cause hindrance to enzymes, as malate dehydrogenase and amino acid oxidase could not use malate-Cr(III) and histidine-Cr(III), respectively. The data are in agreement with the reports of soluble organo-Cr(III) complexes in the environment."
1231722,Panichev et al. 2008,The oxidation of Cr(III) to Cr(VI) in the environment by atmospheric oxygen during the bush fires,"The presence of Cr(VI) in soils and plants of remote unpolluted areas can be explained by partial oxidation of Cr(III) with atmospheric oxygen during seasonable bush fires, which are rather frequent event in South Africa. Experiments with thermal treatment of a veld grass, Hyperthelia dissoluta, in muffle furnace at high temperature, followed by electrothermal atomic absorption spectrometry (ETAAS) determination of chromium, show a remarkable increase in Cr(VI) concentration from initial 2.5 to 23.2% after the treatment of grass ash at 500 degrees C and to 58.1% at 900 degrees C. Before ETAAS determination, the two chromium species of interest were separated by the treatment of samples with 0.1M Na2CO3. Thermodynamic calculations confirm the possibility of Cr(III) to Cr(VI) oxidation with atmospheric oxygen at high temperature in alkaline media, which is typical for vegetation ash. Analysis of field samples show that percent of Cr(VI), in respect to the total amount of chromium increased from initial 2.5% in grass to 9.3% in ash of grass. Without oxidation the percent of Cr(VI) in grass and ash of grass should be a constant value. After the fire Cr(VI) concentration in top soil (0-3 cm) increased from 0.3+/-0.05 to 1.8+/-0.5 microg g(-1) and the total Cr from 26+/-9 to 69+/-14 microg g(-1). The reason for the appearance of additional amount of Cr on top soil can be explained by condensation of chromium species from flame and shouldering ash on a soil surface. The results of studies demonstrate that Cr(VI) is formed by Cr(III) oxidation with atmospheric oxygen at high temperature during bush fires.","The oxidation of Cr(III) to Cr(VI) in the environment by atmospheric oxygen during the bush fires Abs: The presence of Cr(VI) in soils and plants of remote unpolluted areas can be explained by partial oxidation of Cr(III) with atmospheric oxygen during seasonable bush fires, which are rather frequent event in South Africa. Experiments with thermal treatment of a veld grass, Hyperthelia dissoluta, in muffle furnace at high temperature, followed by electrothermal atomic absorption spectrometry (ETAAS) determination of chromium, show a remarkable increase in Cr(VI) concentration from initial 2.5 to 23.2% after the treatment of grass ash at 500 degrees C and to 58.1% at 900 degrees C. Before ETAAS determination, the two chromium species of interest were separated by the treatment of samples with 0.1M Na2CO3. Thermodynamic calculations confirm the possibility of Cr(III) to Cr(VI) oxidation with atmospheric oxygen at high temperature in alkaline media, which is typical for vegetation ash. Analysis of field samples show that percent of Cr(VI), in respect to the total amount of chromium increased from initial 2.5% in grass to 9.3% in ash of grass. Without oxidation the percent of Cr(VI) in grass and ash of grass should be a constant value. After the fire Cr(VI) concentration in top soil (0-3 cm) increased from 0.3+/-0.05 to 1.8+/-0.5 microg g(-1) and the total Cr from 26+/-9 to 69+/-14 microg g(-1). The reason for the appearance of additional amount of Cr on top soil can be explained by condensation of chromium species from flame and shouldering ash on a soil surface. The results of studies demonstrate that Cr(VI) is formed by Cr(III) oxidation with atmospheric oxygen at high temperature during bush fires."
1231721,Stummann et al. 2007,Embryotoxicity hazard assessment of methylmercury and chromium using embryonic stem cells,"The embryonic stem cell test (EST) has been scientifically validated (2001) as an in vitro embryotoxicity test, showing a good overall test accuracy of 78%. Methylmercury (MeHg) was the most significant outlayer identified, as the metal was the only strong in vivo embryotoxicant falsely predicted to be non-embryotoxic. The EST misclassification of MeHg, and the potential environmental exposure and developmental toxic hazards of heavy metals gave us the rationale to investigate whether the EST can correctly predict the embryotoxic potential of two heavy metals different from MeHg. The EST correctly classified trivalent chromium to be non-embryotoxic and hexavalent chromium to be embryotoxic, while we confirmed the misclassification of MeHg. MeHg causes developmental abnormalities in the brain. We therefore aimed to improve the in vitro prediction of MeHg embryotoxicity by including a neuronal ES cell differentiation assay. Differentiation of neuronal-like cells was demonstrated by real-time PCR experiments, showing up-regulation of several neuronal marker genes, and immunohistochemistry, demonstrating the appearance of nestin, neurofilament medium polypeptide, beta-tubulin III and microtubule-associated protein 2 (Mtap2) positive cells. We identified Mtap2 mRNA expression as a sensitive toxicological endpoint for MeHg-induced neuronal embryotoxicity, as Mtap2 mRNA was down-regulated in the presence of non-cytotoxic concentrations of MeHg. Noticeably, several other neuronal marker genes were unaffected by MeHg and Mtap2 expression was not affected until day 14 of differentiation. This implies that the total neuronal-like cell number was unchanged and that the down-regulation of Mtap2 expression reflects neuron-specific toxicity, i.e. instability of the neuron-specific microtubules, and arrest of the neuronal maturation. The fact, that most marker genes were unaffected by MeHg, stresses the importance of including an array of marker genes. In conclusion, our results imply that inclusion of additional target tissues and refinement of the current prediction model may enhance the predictive power of the EST.","Embryotoxicity hazard assessment of methylmercury and chromium using embryonic stem cells Abs: The embryonic stem cell test (EST) has been scientifically validated (2001) as an in vitro embryotoxicity test, showing a good overall test accuracy of 78%. Methylmercury (MeHg) was the most significant outlayer identified, as the metal was the only strong in vivo embryotoxicant falsely predicted to be non-embryotoxic. The EST misclassification of MeHg, and the potential environmental exposure and developmental toxic hazards of heavy metals gave us the rationale to investigate whether the EST can correctly predict the embryotoxic potential of two heavy metals different from MeHg. The EST correctly classified trivalent chromium to be non-embryotoxic and hexavalent chromium to be embryotoxic, while we confirmed the misclassification of MeHg. MeHg causes developmental abnormalities in the brain. We therefore aimed to improve the in vitro prediction of MeHg embryotoxicity by including a neuronal ES cell differentiation assay. Differentiation of neuronal-like cells was demonstrated by real-time PCR experiments, showing up-regulation of several neuronal marker genes, and immunohistochemistry, demonstrating the appearance of nestin, neurofilament medium polypeptide, beta-tubulin III and microtubule-associated protein 2 (Mtap2) positive cells. We identified Mtap2 mRNA expression as a sensitive toxicological endpoint for MeHg-induced neuronal embryotoxicity, as Mtap2 mRNA was down-regulated in the presence of non-cytotoxic concentrations of MeHg. Noticeably, several other neuronal marker genes were unaffected by MeHg and Mtap2 expression was not affected until day 14 of differentiation. This implies that the total neuronal-like cell number was unchanged and that the down-regulation of Mtap2 expression reflects neuron-specific toxicity, i.e. instability of the neuron-specific microtubules, and arrest of the neuronal maturation. The fact, that most marker genes were unaffected by MeHg, stresses the importance of including an array of marker genes. In conclusion, our results imply that inclusion of additional target tissues and refinement of the current prediction model may enhance the predictive power of the EST."
1231720,Xu et al. 2008,Solidification and leaching behaviours of Cr6+ in sludge ceramsite,"Making lightweight ceramsite with sewage sludge is a new effective approach for disposal of sludge. However, there is a concern as to whether the heavy metals such as Cr6+ in sewage sludge can be solidified in ceramsite after sintering. The configuration of Cr6+ in ceramsite was analyzed by X-ray diffraction (XRD) and leaching tests were conducted to determine the effects of sintering temperature, pH and H2O2 concentration on the stabilization of Cr6+ in ceramsite. The results show that leaching of Cr6+ changes little at temperatures above 900 degrees C, and both pH and H2O2 concentration have some effects on the leaching of Cr6+. Leaching test results indicate that Cr6+ is stabilized in ceramsite and cannot be easily released to the environment again as secondary pollution, which eliminates the concern for its application. XRD analysis of ceramsite sintered at 1000 degrees C reveals that the main compounds of Cr6+ in ceramsite are Cr2O3 and FeCrO4. The test results provides a better understanding of the factors that affect the mobility of Cr6+, and show it is a safe way to make ceramsite with sludge as an additive.","Solidification and leaching behaviours of Cr6+ in sludge ceramsite Abs: Making lightweight ceramsite with sewage sludge is a new effective approach for disposal of sludge. However, there is a concern as to whether the heavy metals such as Cr6+ in sewage sludge can be solidified in ceramsite after sintering. The configuration of Cr6+ in ceramsite was analyzed by X-ray diffraction (XRD) and leaching tests were conducted to determine the effects of sintering temperature, pH and H2O2 concentration on the stabilization of Cr6+ in ceramsite. The results show that leaching of Cr6+ changes little at temperatures above 900 degrees C, and both pH and H2O2 concentration have some effects on the leaching of Cr6+. Leaching test results indicate that Cr6+ is stabilized in ceramsite and cannot be easily released to the environment again as secondary pollution, which eliminates the concern for its application. XRD analysis of ceramsite sintered at 1000 degrees C reveals that the main compounds of Cr6+ in ceramsite are Cr2O3 and FeCrO4. The test results provides a better understanding of the factors that affect the mobility of Cr6+, and show it is a safe way to make ceramsite with sludge as an additive."
1231719,Wang et al. 2008,Removal of Cr(VI) from aqueous solutions by low-cost biosorbents: marine macroalgae and agricultural by-products,"In this study, adsorption of Cr(VI) onto the four low-cost biosorbents (Laminaria japonica, P. yezoensis Ueda, rice bran and wheat bran) was investigated depending on solution pH, contact time, adsorbent concentration and adsorption isotherms by employing batch adsorption technique. The adsorption capacities were significantly influenced by solution pH, with lower pH favoring higher Cr(VI) removal for various biosorbents. The ionic strength of NaCl was also observed to have a significant impact on the Cr(VI) adsorption due to the competition of Cl(-) in the aqueous solutions. The batch equilibrium data were correlated to Langmuir and Freundlich isotherms and the data fitted better to the Freundlich isotherm equation. The apparent thermodynamic parameters were calculated for each of the four biosorbents and the obtained numerical values showed that the Cr(VI) adsorption onto the various low-cost biosorbents is spontaneous, entropy-driven and endothermic processes. The batch kinetic data were correlated to the pseudo-first order and pseudo-second order models and the data fitted better to the pseudo-second order equation. An intraparticle diffusion model was applied to investigate the adsorption mechanisms. The adsorption capacities for various biosorbents studied in this work were inversely proportional to the adsorbent concentrations.","Removal of Cr(VI) from aqueous solutions by low-cost biosorbents: marine macroalgae and agricultural by-products Abs: In this study, adsorption of Cr(VI) onto the four low-cost biosorbents (Laminaria japonica, P. yezoensis Ueda, rice bran and wheat bran) was investigated depending on solution pH, contact time, adsorbent concentration and adsorption isotherms by employing batch adsorption technique. The adsorption capacities were significantly influenced by solution pH, with lower pH favoring higher Cr(VI) removal for various biosorbents. The ionic strength of NaCl was also observed to have a significant impact on the Cr(VI) adsorption due to the competition of Cl(-) in the aqueous solutions. The batch equilibrium data were correlated to Langmuir and Freundlich isotherms and the data fitted better to the Freundlich isotherm equation. The apparent thermodynamic parameters were calculated for each of the four biosorbents and the obtained numerical values showed that the Cr(VI) adsorption onto the various low-cost biosorbents is spontaneous, entropy-driven and endothermic processes. The batch kinetic data were correlated to the pseudo-first order and pseudo-second order models and the data fitted better to the pseudo-second order equation. An intraparticle diffusion model was applied to investigate the adsorption mechanisms. The adsorption capacities for various biosorbents studied in this work were inversely proportional to the adsorbent concentrations."
1231718,Srinivas et al. 2007,Reducing the allergenic hexavalent chromium in leather to hypoallergenic trivalent chromium for prevention of leather dermatitis,,Reducing the allergenic hexavalent chromium in leather to hypoallergenic trivalent chromium for prevention of leather dermatitis Abs: 
1231717,Morales et al. 2007,Efficient removal of hexavalent chromium by a tolerant Streptomyces sp. affected by the toxic effect of metal exposure,"<strong>AIMS: </strong>To isolate and analyse chromium-resistant micro-organisms suitable for bioremediation.<br /><br /><strong>METHODS AND RESULTS: </strong>Strain CG252, with a minimal inhibitory concentration of 500 microg ml(-1), was isolated from contaminated soils and identified as a Streptomyces sp. by 16S rDNA sequence analysis. Assays carried out at various Cr(VI) concentrations indicated that chromium removal was more efficient at lower concentrations and that this activity resulted in accumulation of Cr(III). Atomic adsorption analysis indicated that the chromium removed was not associated with cell mass and activity assays showed that the capacity to reduce Cr(VI) was most probably due to a soluble cytosolic enzyme. Cells grown as biofilms showed enhanced removal of Cr(VI) with respect to planktonic cells, while analysis of growth and colony morphology indicated that Cr(VI) had a toxic effect on this strain.<br /><br /><strong>CONCLUSIONS: </strong>Streptomyces sp. CG252 tolerated heavy metals and elevated levels of chromium, despite its negative effect on growth and development, and was efficient at removing Cr(VI) by promoting reduction to Cr(III).<br /><br /><strong>SIGNIFICANCE AND IMPACT OF THE STUDY: </strong>Strain CG252's capacity to tolerate heavy metals and to reduce Cr(VI) to the less toxic Cr(III), especially when forming biofilms, makes it a promising candidate for detoxification of sites containing this heavy metal.","Efficient removal of hexavalent chromium by a tolerant Streptomyces sp. affected by the toxic effect of metal exposure Abs: <strong>AIMS: </strong>To isolate and analyse chromium-resistant micro-organisms suitable for bioremediation.<br /><br /><strong>METHODS AND RESULTS: </strong>Strain CG252, with a minimal inhibitory concentration of 500 microg ml(-1), was isolated from contaminated soils and identified as a Streptomyces sp. by 16S rDNA sequence analysis. Assays carried out at various Cr(VI) concentrations indicated that chromium removal was more efficient at lower concentrations and that this activity resulted in accumulation of Cr(III). Atomic adsorption analysis indicated that the chromium removed was not associated with cell mass and activity assays showed that the capacity to reduce Cr(VI) was most probably due to a soluble cytosolic enzyme. Cells grown as biofilms showed enhanced removal of Cr(VI) with respect to planktonic cells, while analysis of growth and colony morphology indicated that Cr(VI) had a toxic effect on this strain.<br /><br /><strong>CONCLUSIONS: </strong>Streptomyces sp. CG252 tolerated heavy metals and elevated levels of chromium, despite its negative effect on growth and development, and was efficient at removing Cr(VI) by promoting reduction to Cr(III).<br /><br /><strong>SIGNIFICANCE AND IMPACT OF THE STUDY: </strong>Strain CG252's capacity to tolerate heavy metals and to reduce Cr(VI) to the less toxic Cr(III), especially when forming biofilms, makes it a promising candidate for detoxification of sites containing this heavy metal."
1231716,Castorina et al. 2008,Expression profile of ErbB receptor's family in human alveolar type 2-like cell line A549 exposed to hexavalent chromium,"Occupational exposure to hexavalent chromium (Cr (VI)) compounds is associated with increased risk of pulmonary disease. In the present study we have investigated temporal expression of ErbB's receptors family in A549 cells after exposure to Cr (VI). Treatment with 10 microM or 300 microM of Na2CrO4 induced apoptotic cell death within 24h. Based on data obtained by ELISA cell death detection method and fluorescence microscopy, the concentration of 10 microM was chosen to study the expression of ErbB receptors family. Such concentration reflects a condition of acute toxicity in which cells survived up to 24h. Real time quantitative PCR has been performed to analyze the expression profiles of ErbB family genes following chromium toxicity. The expression of EGFR and ErbB2 receptors was significantly reduced after 1h and 4h of treatment while ErbB2 receptor was significantly increased and EGFR receptor returned to basal value after 24h. Instead, ErbB3 receptor was overexpressed after 1h, returned to basal level after 4h and increased its level after 24h. Exposure to chromium did not change expression level of ErbB4 receptor in A549 cell line. The present data suggests that expression changes in ErbB receptors might have a role in the carcinogenic effects induced by this pneumotoxic agent.","Expression profile of ErbB receptor's family in human alveolar type 2-like cell line A549 exposed to hexavalent chromium Abs: Occupational exposure to hexavalent chromium (Cr (VI)) compounds is associated with increased risk of pulmonary disease. In the present study we have investigated temporal expression of ErbB's receptors family in A549 cells after exposure to Cr (VI). Treatment with 10 microM or 300 microM of Na2CrO4 induced apoptotic cell death within 24h. Based on data obtained by ELISA cell death detection method and fluorescence microscopy, the concentration of 10 microM was chosen to study the expression of ErbB receptors family. Such concentration reflects a condition of acute toxicity in which cells survived up to 24h. Real time quantitative PCR has been performed to analyze the expression profiles of ErbB family genes following chromium toxicity. The expression of EGFR and ErbB2 receptors was significantly reduced after 1h and 4h of treatment while ErbB2 receptor was significantly increased and EGFR receptor returned to basal value after 24h. Instead, ErbB3 receptor was overexpressed after 1h, returned to basal level after 4h and increased its level after 24h. Exposure to chromium did not change expression level of ErbB4 receptor in A549 cell line. The present data suggests that expression changes in ErbB receptors might have a role in the carcinogenic effects induced by this pneumotoxic agent."
1231715,Demirbas et al. 2008,Error analysis of equilibrium studies for the almond shell activated carbon adsorption of Cr(VI) from aqueous solutions,"In this study, the preparation of activated carbon from almond shell with H2SO4 activation and its ability to remove toxic hexavalent chromium from aqueous solutions are reported. The influences of several operating parameters such as pH, particle size and temperature on the adsorption capacity were investigated. Adsorption of Cr(VI) is found to be highly pH, particle size and temperature dependent. Four adsorption isotherm models namely, Langmuir, Freundlich, Tempkin and Dubinin-Radushkevich were used to analyze the equilibrium data. The Langmuir isotherm provided the best correlation for Cr(VI) onto the almond shell activated carbon (ASC). Adsorption capacity was calculated from the Langmuir isotherm as 190.3 mg/g at 323 K. Thermodynamic parameters were evaluated and the adsorption was endothermic showing monolayer adsorption of Cr(VI). Five error functions were used to treat the equilibrium data using non-linear optimization techniques for evaluating the fit of the isotherm equations. The highest correlation for the isotherm equations in this system was obtained for the Freundlich isotherm. ASC is found to be inexpensive and effective adsorbent for removal of Cr(VI) from aqueous solutions.","Error analysis of equilibrium studies for the almond shell activated carbon adsorption of Cr(VI) from aqueous solutions Abs: In this study, the preparation of activated carbon from almond shell with H2SO4 activation and its ability to remove toxic hexavalent chromium from aqueous solutions are reported. The influences of several operating parameters such as pH, particle size and temperature on the adsorption capacity were investigated. Adsorption of Cr(VI) is found to be highly pH, particle size and temperature dependent. Four adsorption isotherm models namely, Langmuir, Freundlich, Tempkin and Dubinin-Radushkevich were used to analyze the equilibrium data. The Langmuir isotherm provided the best correlation for Cr(VI) onto the almond shell activated carbon (ASC). Adsorption capacity was calculated from the Langmuir isotherm as 190.3 mg/g at 323 K. Thermodynamic parameters were evaluated and the adsorption was endothermic showing monolayer adsorption of Cr(VI). Five error functions were used to treat the equilibrium data using non-linear optimization techniques for evaluating the fit of the isotherm equations. The highest correlation for the isotherm equations in this system was obtained for the Freundlich isotherm. ASC is found to be inexpensive and effective adsorbent for removal of Cr(VI) from aqueous solutions."
1231712,Hook et al. 2008,"Gene expression profiles in rainbow trout, Onchorynchus mykiss, exposed to a simple chemical mixture","Among proposed uses for microarrays in environmental toxiciology is the identification of key contributors to toxicity within a mixture. However, it remains uncertain whether the transcriptomic profiles resulting from exposure to a mixture have patterns of altered gene expression that contain identifiable contributions from each toxicant component. We exposed isogenic rainbow trout Onchorynchus mykiss, to sublethal levels of ethynylestradiol, 2,2,4,4-tetrabromodiphenyl ether, and chromium VI or to a mixture of all three toxicants Fluorescently labeled complementary DNA (cDNA) were generated and hybridized against a commercially available Salmonid array spotted with 16,000 cDNAs. Data were analyzed using analysis of variance (p&lt;0.05) with a Benjamani-Hochberg multiple test correction (Genespring [Agilent] software package) to identify up and downregulated genes. Gene clustering patterns that can be used as &quot;expression signatures&quot; were determined using hierarchical cluster analysis. The gene ontology terms associated with significantly altered genes were also used to identify functional groups that were associated with toxicant exposure. Cross-ontological analytics approach was used to assign functional annotations to genes with &quot;unknown&quot; function. Our analysis indicates that transcriptomic profiles resulting from the mixture exposure resemble those of the individual contaminant exposures, but are not a simple additive list. However, patterns of altered genes representative of each component of the mixture are clearly discernible, and the functional classes of genes altered represent the individual components of the mixture. These findings indicate that the use of microarrays to identify transcriptomic profiles may aid in the identification of key stressors within a chemical mixture, ultimately improving environmental assessment.","Gene expression profiles in rainbow trout, Onchorynchus mykiss, exposed to a simple chemical mixture Abs: Among proposed uses for microarrays in environmental toxiciology is the identification of key contributors to toxicity within a mixture. However, it remains uncertain whether the transcriptomic profiles resulting from exposure to a mixture have patterns of altered gene expression that contain identifiable contributions from each toxicant component. We exposed isogenic rainbow trout Onchorynchus mykiss, to sublethal levels of ethynylestradiol, 2,2,4,4-tetrabromodiphenyl ether, and chromium VI or to a mixture of all three toxicants Fluorescently labeled complementary DNA (cDNA) were generated and hybridized against a commercially available Salmonid array spotted with 16,000 cDNAs. Data were analyzed using analysis of variance (p&lt;0.05) with a Benjamani-Hochberg multiple test correction (Genespring [Agilent] software package) to identify up and downregulated genes. Gene clustering patterns that can be used as &quot;expression signatures&quot; were determined using hierarchical cluster analysis. The gene ontology terms associated with significantly altered genes were also used to identify functional groups that were associated with toxicant exposure. Cross-ontological analytics approach was used to assign functional annotations to genes with &quot;unknown&quot; function. Our analysis indicates that transcriptomic profiles resulting from the mixture exposure resemble those of the individual contaminant exposures, but are not a simple additive list. However, patterns of altered genes representative of each component of the mixture are clearly discernible, and the functional classes of genes altered represent the individual components of the mixture. These findings indicate that the use of microarrays to identify transcriptomic profiles may aid in the identification of key stressors within a chemical mixture, ultimately improving environmental assessment."
1231711,Kiliç and  Dönmez 2008,"Environmental conditions affecting exopolysaccharide production by Pseudomonas aeruginosa, Micrococcus sp., and Ochrobactrum sp","Three different chromium-resistant microorganisms (Pseudomonas aeruginosa, Micrococcus sp., and Ochrobactrum sp.) were tested with regard to their EPS production at different pH levels, temperatures, Cr(VI) concentrations, and incubation periods. The optimum pH level was 7 for P. aeruginosa and Micrococcus sp., while it was 8 for Ochrobactrum sp. according to the highest EPS amount at 100 mg/L Cr(VI) concentration. The highest production of EPSs by the three bacteria was obtained under different environmental conditions. P. aeruginosa produced the highest EPS (863.3 mg/L) after incubation for 96 h on media with 50 mg/L Cr(VI) at 20 degrees C, Micrococcus sp. gave the highest yield (444.6 mg/L) after incubation for 72 h on media with 100 mg/L Cr(VI) at the same temperature, and Ochrobactrum sp. had the highest production (430.5 mg/L) on media with 150 mg/L Cr(VI) at 30 degrees C at the end of 48 h of incubation.","Environmental conditions affecting exopolysaccharide production by Pseudomonas aeruginosa, Micrococcus sp., and Ochrobactrum sp Abs: Three different chromium-resistant microorganisms (Pseudomonas aeruginosa, Micrococcus sp., and Ochrobactrum sp.) were tested with regard to their EPS production at different pH levels, temperatures, Cr(VI) concentrations, and incubation periods. The optimum pH level was 7 for P. aeruginosa and Micrococcus sp., while it was 8 for Ochrobactrum sp. according to the highest EPS amount at 100 mg/L Cr(VI) concentration. The highest production of EPSs by the three bacteria was obtained under different environmental conditions. P. aeruginosa produced the highest EPS (863.3 mg/L) after incubation for 96 h on media with 50 mg/L Cr(VI) at 20 degrees C, Micrococcus sp. gave the highest yield (444.6 mg/L) after incubation for 72 h on media with 100 mg/L Cr(VI) at the same temperature, and Ochrobactrum sp. had the highest production (430.5 mg/L) on media with 150 mg/L Cr(VI) at 30 degrees C at the end of 48 h of incubation."
1231708,Yu and  Gu 2008,Effect of available nitrogen on phytoavailability and bioaccumulation of hexavalent and trivalent chromium in hankow willows (Salix matsudana Koidz),"The effect of available nitrogen in nutrient solution on removal of two chemical forms of chromium (Cr) by plants was investigated. Pre-rooted hankow willows (Salix matsudana Koidz) were grown in a hydroponic solution system with or without nitrogen, and amended with hexavalent chromium [Cr (VI)] or trivalent chromium [Cr (III)] at 25.0+/-0.5 degrees C for 192 h. The results revealed that higher removal of Cr by plants was achieved from the hydroponic solutions without any nitrogen than those containing nitrogen. Although faster removal of Cr (VI) than Cr (III) was observed, translocation of Cr (III) within plant materials was more efficient than Cr (VI). Substantial difference existed in the distribution of Cr in different parts of plant tissues due to the nitrogen in nutrient solutions (p&lt;0.05): lower stems were the major sink for both Cr species in willows grown in the N-free nutrient solutions and more Cr was accumulated in the roots of plants in N-containing ones. No significant difference was found in the removal rate of Cr (VI) between willows grown in the N-free and N-containing solutions (p&gt;0.05). Removal rates of Cr (III) decreased linearly with the strength of nutrient solutions with or without N addition (p&lt;0.01). Translocation efficiencies of both Cr species increased proportionally with the strength of N-containing nutrient solutions and decreased with the strength of N-free nutrient solutions. Results suggest that uptake and translocation mechanisms of Cr (VI) and Cr (III) are apparently different in hankow willows. The presence of easily available nitrogen and other nutrient elements in the nutrient solutions had a more pronounced influence on the uptake of Cr (III) than Cr (VI). Nitrogen availability and quantities in the ambient environment will affect the translocation of both Cr species and their distribution in willows in phytoremediation.","Effect of available nitrogen on phytoavailability and bioaccumulation of hexavalent and trivalent chromium in hankow willows (Salix matsudana Koidz) Abs: The effect of available nitrogen in nutrient solution on removal of two chemical forms of chromium (Cr) by plants was investigated. Pre-rooted hankow willows (Salix matsudana Koidz) were grown in a hydroponic solution system with or without nitrogen, and amended with hexavalent chromium [Cr (VI)] or trivalent chromium [Cr (III)] at 25.0+/-0.5 degrees C for 192 h. The results revealed that higher removal of Cr by plants was achieved from the hydroponic solutions without any nitrogen than those containing nitrogen. Although faster removal of Cr (VI) than Cr (III) was observed, translocation of Cr (III) within plant materials was more efficient than Cr (VI). Substantial difference existed in the distribution of Cr in different parts of plant tissues due to the nitrogen in nutrient solutions (p&lt;0.05): lower stems were the major sink for both Cr species in willows grown in the N-free nutrient solutions and more Cr was accumulated in the roots of plants in N-containing ones. No significant difference was found in the removal rate of Cr (VI) between willows grown in the N-free and N-containing solutions (p&gt;0.05). Removal rates of Cr (III) decreased linearly with the strength of nutrient solutions with or without N addition (p&lt;0.01). Translocation efficiencies of both Cr species increased proportionally with the strength of N-containing nutrient solutions and decreased with the strength of N-free nutrient solutions. Results suggest that uptake and translocation mechanisms of Cr (VI) and Cr (III) are apparently different in hankow willows. The presence of easily available nitrogen and other nutrient elements in the nutrient solutions had a more pronounced influence on the uptake of Cr (III) than Cr (VI). Nitrogen availability and quantities in the ambient environment will affect the translocation of both Cr species and their distribution in willows in phytoremediation."
1231704,Raghunathan et al. 2009,Comparative chronic in vitro toxicity of hexavalent chromium to osteoblasts and monocytes,"There is increasing concern regarding the long-term biological effects of exposure to low concentrations of metal ions, particularly chromium, in patients following implantation of metal-on-metal hip prostheses. To investigate this, we have evaluated the chronic in vitro response to clinically relevant concentrations of chromium VI in osteoblasts and monocytes over a 4-week period in continuous culture. The cell viability, intracellular reduced glutathione content, glutathione reductase activity and expression, and expression of glutamate cysteine ligase were monitored in both cell types. Monocytes were more susceptible to the toxicity of the metal, and at the end of 4 weeks exposure to 0.5 microM Cr VI, the protein content of cultures had declined to 23.4% +/- 1.0% of control cultures. Both cell types demonstrated temporal increases in reduced glutathione levels, glutathione reductase activity, and glutamate cysteine ligase expression. Only osteoblasts showed a transcriptional increase in reductase expression. Data suggest that both cell types mount an adaptive response to chronic exposure to Cr VI, but this is more potent in osteoblasts, and results in the relative resilience of this cell type to the effects of Cr VI on cell viability.","Comparative chronic in vitro toxicity of hexavalent chromium to osteoblasts and monocytes Abs: There is increasing concern regarding the long-term biological effects of exposure to low concentrations of metal ions, particularly chromium, in patients following implantation of metal-on-metal hip prostheses. To investigate this, we have evaluated the chronic in vitro response to clinically relevant concentrations of chromium VI in osteoblasts and monocytes over a 4-week period in continuous culture. The cell viability, intracellular reduced glutathione content, glutathione reductase activity and expression, and expression of glutamate cysteine ligase were monitored in both cell types. Monocytes were more susceptible to the toxicity of the metal, and at the end of 4 weeks exposure to 0.5 microM Cr VI, the protein content of cultures had declined to 23.4% +/- 1.0% of control cultures. Both cell types demonstrated temporal increases in reduced glutathione levels, glutathione reductase activity, and glutamate cysteine ligase expression. Only osteoblasts showed a transcriptional increase in reductase expression. Data suggest that both cell types mount an adaptive response to chronic exposure to Cr VI, but this is more potent in osteoblasts, and results in the relative resilience of this cell type to the effects of Cr VI on cell viability."
1231702,Joseph et al. 2008,Heme-oxygenase 1 gene expression is a marker for hexavalent chromium-induced stress and toxicity in human dermal fibroblasts,"Several adverse health effects, including irritant and allergic contact dermatitis, have been reported among workers who are occupationally exposed to chromium-containing compounds. Human dermal fibroblasts were used as an in vitro experimental model to study the potential mechanisms underlying hexavalent chromium [Cr(VI)]-induced dermal toxicity. Exposure of the fibroblasts to 5 microM Cr(VI) (LC50 for a 24-h exposure period) followed by microarray analysis of the gene expression profile revealed overexpression of several genes including those involved in cell stress response. The cellular level of glutathione, the major antioxidant molecule present in the cells, was significantly lower in the Cr(VI)-treated cells compared to the corresponding control cells. The Cr(VI)-induced overexpression of heme-oxygenase 1 messenger RNA (HO-1) in the fibroblasts was significantly blocked by actinomycin D and by inhibitors of MAP kinase pathways. The Cr(VI)-induced cytotoxicity and the overexpression of the HO-1 gene were dependent on the glutathione level of the fibroblasts. Buthionine sulfoximine-mediated GSH depletion resulted in enhanced Cr(VI) cytotoxicity and further overexpression of the HO-1 gene. On the other hand, elevated cellular levels of glutathione resulting from pretreating the cells with GSH significantly protected the cells against the Cr(VI)-induced cytotoxicity and blocked the HO-1 gene's overexpression. Pretreating the fibroblasts with N-acetyl cysteine also significantly reduced the Cr(VI)-induced cytotoxicity and overexpression of the HO-1 gene. In conclusion, depletion of GSH leading to cellular stress is a major mechanism responsible for Cr(VI)-induced cytotoxicity. Furthermore, the expression level of HO-1 gene is a marker for Cr(VI)-induced cell stress leading to cytotoxicity.","Heme-oxygenase 1 gene expression is a marker for hexavalent chromium-induced stress and toxicity in human dermal fibroblasts Abs: Several adverse health effects, including irritant and allergic contact dermatitis, have been reported among workers who are occupationally exposed to chromium-containing compounds. Human dermal fibroblasts were used as an in vitro experimental model to study the potential mechanisms underlying hexavalent chromium [Cr(VI)]-induced dermal toxicity. Exposure of the fibroblasts to 5 microM Cr(VI) (LC50 for a 24-h exposure period) followed by microarray analysis of the gene expression profile revealed overexpression of several genes including those involved in cell stress response. The cellular level of glutathione, the major antioxidant molecule present in the cells, was significantly lower in the Cr(VI)-treated cells compared to the corresponding control cells. The Cr(VI)-induced overexpression of heme-oxygenase 1 messenger RNA (HO-1) in the fibroblasts was significantly blocked by actinomycin D and by inhibitors of MAP kinase pathways. The Cr(VI)-induced cytotoxicity and the overexpression of the HO-1 gene were dependent on the glutathione level of the fibroblasts. Buthionine sulfoximine-mediated GSH depletion resulted in enhanced Cr(VI) cytotoxicity and further overexpression of the HO-1 gene. On the other hand, elevated cellular levels of glutathione resulting from pretreating the cells with GSH significantly protected the cells against the Cr(VI)-induced cytotoxicity and blocked the HO-1 gene's overexpression. Pretreating the fibroblasts with N-acetyl cysteine also significantly reduced the Cr(VI)-induced cytotoxicity and overexpression of the HO-1 gene. In conclusion, depletion of GSH leading to cellular stress is a major mechanism responsible for Cr(VI)-induced cytotoxicity. Furthermore, the expression level of HO-1 gene is a marker for Cr(VI)-induced cell stress leading to cytotoxicity."
1231701,Mishra and  Mohanty 2008,"Histopathological effects of hexavalent chromium in the ovary of a fresh water fish, Channa punctatus (Bloch)","The histopathological effects of hexavalent chromium (Cr VI) in the ovary of a fresh water teleost, Channa punctatus were investigated. An exposure-dependent alteration in ovarian histology is reported. For both acute and chronic exposures to Cr (VI), the percentages of atretic oocytes were increased; this increase was more pronounced in the acute exposure group. A decrease in percentage of vitellogenic oocytes was observed in the chronic exposure group indicating impairment of vitellogenesis. The hepatocellular vacuolization and atrophy along with pyknotic nuclei in both acute and chronic chromium exposed fish liver supports the vitellogenic impairment. The observed alterations may be due to both direct cytotoxic effect of Cr (VI) on the ovary as well as mediation by overall systemic toxicity affecting other vital organs.","Histopathological effects of hexavalent chromium in the ovary of a fresh water fish, Channa punctatus (Bloch) Abs: The histopathological effects of hexavalent chromium (Cr VI) in the ovary of a fresh water teleost, Channa punctatus were investigated. An exposure-dependent alteration in ovarian histology is reported. For both acute and chronic exposures to Cr (VI), the percentages of atretic oocytes were increased; this increase was more pronounced in the acute exposure group. A decrease in percentage of vitellogenic oocytes was observed in the chronic exposure group indicating impairment of vitellogenesis. The hepatocellular vacuolization and atrophy along with pyknotic nuclei in both acute and chronic chromium exposed fish liver supports the vitellogenic impairment. The observed alterations may be due to both direct cytotoxic effect of Cr (VI) on the ovary as well as mediation by overall systemic toxicity affecting other vital organs."
1231700,Séby et al. 2008,Development of analytical procedures for the determination of hexavalent chromium in corrosion prevention coatings used in the automotive industry,"The European directive 2000/53/EC limits the use of Cr(VI) in vehicle manufacturing. Although a maximum of 2 g of Cr(VI) was authorised per vehicle for corrosion prevention coatings of key components, since July 2007 its use has been prohibited except for some particular applications. Therefore, the objective of this work was to develop direct analytical procedures for Cr(VI) determination in the different steel coatings used for screws. Instead of working directly with screws, the optimisation of the procedures was carried out with metallic plates homogeneously coated to improve the data comparability. Extraction of Cr(VI) from the metallic parts was performed by sonication. Two extraction solutions were tested: a direct water extraction solution used in standard protocols and an ammonium/ammonia buffer solution at pH 8.9. The extracts were further analysed for Cr speciation by high-performance liquid chromatography (HPLC) inductively coupled plasma (ICP) atomic emission spectrometry or HPLC ICP mass spectrometry depending on the concentration level. When possible, the coatings were also directly analysed by solid speciation techniques (X-ray photoelectron spectroscopy, XPS, and X-ray absorption near-edge structure, XANES) for validation of the results. Very good results between the different analytical approaches were obtained for the sample of coating made up of a heated paint containing Zn, Al and Cr when using the extracting buffer solution at pH 8.9. After a repeated four-step extraction procedure on the same portion test, taking into account the depth of the surface layer reached, good agreement with XPS and XANES results was obtained. In contrast, for the coatings composed of an alkaline Zn layer where Cr(VI) and Cr(III) are deposited, only the extraction procedure using water allowed the detection of Cr(VI). To elucidate the Cr(VI) reduction during extraction at pH 8.9, the reactivity of Cr(VI) towards different species of Zn generally present in the coatings (metallic Zn and zinc oxide) was studied. The results showed that metallic Zn rapidly reduces Cr(VI), whereas this reaction is less evident in the presence of zinc oxide. Water was then retained for coatings containing metallic Zn.","Development of analytical procedures for the determination of hexavalent chromium in corrosion prevention coatings used in the automotive industry Abs: The European directive 2000/53/EC limits the use of Cr(VI) in vehicle manufacturing. Although a maximum of 2 g of Cr(VI) was authorised per vehicle for corrosion prevention coatings of key components, since July 2007 its use has been prohibited except for some particular applications. Therefore, the objective of this work was to develop direct analytical procedures for Cr(VI) determination in the different steel coatings used for screws. Instead of working directly with screws, the optimisation of the procedures was carried out with metallic plates homogeneously coated to improve the data comparability. Extraction of Cr(VI) from the metallic parts was performed by sonication. Two extraction solutions were tested: a direct water extraction solution used in standard protocols and an ammonium/ammonia buffer solution at pH 8.9. The extracts were further analysed for Cr speciation by high-performance liquid chromatography (HPLC) inductively coupled plasma (ICP) atomic emission spectrometry or HPLC ICP mass spectrometry depending on the concentration level. When possible, the coatings were also directly analysed by solid speciation techniques (X-ray photoelectron spectroscopy, XPS, and X-ray absorption near-edge structure, XANES) for validation of the results. Very good results between the different analytical approaches were obtained for the sample of coating made up of a heated paint containing Zn, Al and Cr when using the extracting buffer solution at pH 8.9. After a repeated four-step extraction procedure on the same portion test, taking into account the depth of the surface layer reached, good agreement with XPS and XANES results was obtained. In contrast, for the coatings composed of an alkaline Zn layer where Cr(VI) and Cr(III) are deposited, only the extraction procedure using water allowed the detection of Cr(VI). To elucidate the Cr(VI) reduction during extraction at pH 8.9, the reactivity of Cr(VI) towards different species of Zn generally present in the coatings (metallic Zn and zinc oxide) was studied. The results showed that metallic Zn rapidly reduces Cr(VI), whereas this reaction is less evident in the presence of zinc oxide. Water was then retained for coatings containing metallic Zn."
1231697,Scheepers et al. 2008,Characterisation of exposure to total and hexavalent chromium of welders using biological monitoring,"Inhalation exposure to total and hexavalent chromium (TCr and HCr) was assessed by personal air sampling and biological monitoring in 53 welders and 20 references. Median inhalation exposure levels of TCr were 1.3, 6.0, and 5.4 microg/m(3) for welders of mild steel (MS, &lt;5% alloys), high alloy steel (HAS, &gt;5% alloys), and stainless steel (SS, &gt;26% alloys), respectively. The median exposures to HCr compounds were 0.23, 0.20, and 0.08 microg/m(3), respectively. Median concentrations of TCr in urine, blood plasma and erythrocytes were elevated in all welders, compared with the corresponding median concentrations in the reference group (p&lt;0.005). The TCr levels observed in plasma were two-fold higher in welders of SS and HAS than in welders of MS (p&lt;0.01). Exposure to HCr as indicated by median total content of Cr in erythrocytes was 10 microg/L in welders of SS, MS and HAS. Uptake of TCr during the shift was confirmed for welders of SS by a median increase of urinary TCr from pre- to post-shift of 0.30 microg/g creatinine. For welders of MS and HAS as a group TCr was not increased.","Characterisation of exposure to total and hexavalent chromium of welders using biological monitoring Abs: Inhalation exposure to total and hexavalent chromium (TCr and HCr) was assessed by personal air sampling and biological monitoring in 53 welders and 20 references. Median inhalation exposure levels of TCr were 1.3, 6.0, and 5.4 microg/m(3) for welders of mild steel (MS, &lt;5% alloys), high alloy steel (HAS, &gt;5% alloys), and stainless steel (SS, &gt;26% alloys), respectively. The median exposures to HCr compounds were 0.23, 0.20, and 0.08 microg/m(3), respectively. Median concentrations of TCr in urine, blood plasma and erythrocytes were elevated in all welders, compared with the corresponding median concentrations in the reference group (p&lt;0.005). The TCr levels observed in plasma were two-fold higher in welders of SS and HAS than in welders of MS (p&lt;0.01). Exposure to HCr as indicated by median total content of Cr in erythrocytes was 10 microg/L in welders of SS, MS and HAS. Uptake of TCr during the shift was confirmed for welders of SS by a median increase of urinary TCr from pre- to post-shift of 0.30 microg/g creatinine. For welders of MS and HAS as a group TCr was not increased."
1231695,Moon et al. 2008,Particle size and pH effects on remediation of chromite ore processing residue using calcium polysulfide (CaS5),"A long-term bench scale treatability study was performed to assess the ability to remediate chromite ore processing residue (COPR) using calcium polysulfide (CaS(5)). COPR materials were characterized with respect to particle size, pH, curing period and mineralogy. A stoichiometric ratio of sulfide species to hexavalent chromium (Cr(6+)) of 2 was used for the long-term treatment of COPR. The effectiveness of CaS(5) treatment was assessed using the toxicity characteristic leaching procedure (TCLP), alkaline digestion, and X-ray absorption near edge structure (XANES) analyses. The formation of ettringite, known as a heaving agent, was investigated following the treatment of CaS(5), using X-ray powder diffraction (XRPD) and scanning electron microscopy (SEM) along with an energy dispersive X-ray spectroscopy (EDX). Overall, after a curing period of 18 months, the TCLP total chromium (Cr) and alkaline digestion (Cr(6+)) results obtained from the treatability study showed that the concentrations were lower than 5 mg L(-1) and 9 mg kg(-1), respectively. However, XANES results obtained from samples cured for 18 months showed that all of the treated samples had higher Cr(6+) concentrations than shown using alkaline digestion. The lowest XANES Cr(6+) concentration of 610.2 mg kg(-1) was obtained from the sample with a particle size less than 0.075 mm and a pH value of 9. Particle size reduction prior to the addition of the reductant, along with pH reduction was found to be strongly associated with the treatment performance. Ettringite formation, due to pH increase over time in the samples, where the initial pH was adjusted to 9, was verified by XRPD and SEM-EDX analyses, indicating that a pH less than 9 should be maintained to avoid ettringite formation.","Particle size and pH effects on remediation of chromite ore processing residue using calcium polysulfide (CaS5) Abs: A long-term bench scale treatability study was performed to assess the ability to remediate chromite ore processing residue (COPR) using calcium polysulfide (CaS(5)). COPR materials were characterized with respect to particle size, pH, curing period and mineralogy. A stoichiometric ratio of sulfide species to hexavalent chromium (Cr(6+)) of 2 was used for the long-term treatment of COPR. The effectiveness of CaS(5) treatment was assessed using the toxicity characteristic leaching procedure (TCLP), alkaline digestion, and X-ray absorption near edge structure (XANES) analyses. The formation of ettringite, known as a heaving agent, was investigated following the treatment of CaS(5), using X-ray powder diffraction (XRPD) and scanning electron microscopy (SEM) along with an energy dispersive X-ray spectroscopy (EDX). Overall, after a curing period of 18 months, the TCLP total chromium (Cr) and alkaline digestion (Cr(6+)) results obtained from the treatability study showed that the concentrations were lower than 5 mg L(-1) and 9 mg kg(-1), respectively. However, XANES results obtained from samples cured for 18 months showed that all of the treated samples had higher Cr(6+) concentrations than shown using alkaline digestion. The lowest XANES Cr(6+) concentration of 610.2 mg kg(-1) was obtained from the sample with a particle size less than 0.075 mm and a pH value of 9. Particle size reduction prior to the addition of the reductant, along with pH reduction was found to be strongly associated with the treatment performance. Ettringite formation, due to pH increase over time in the samples, where the initial pH was adjusted to 9, was verified by XRPD and SEM-EDX analyses, indicating that a pH less than 9 should be maintained to avoid ettringite formation."
1231694,Li et al. 2009,The role of iron in hexavalent chromium reduction by municipal landfill leachate,"The function of iron (ferric (Fe(III)) and ferrous (Fe(II))) in the hexavalent chromium (Cr(VI)) reduction mechanism by bacteria in municipal landfill leachate (MLL) was assessed. Evidence of an &quot;electron shuttle&quot; mechanism was observed, whereby the Cr(VI) was reduced to trivalent chromium (Cr(III)) by Fe(II) with the resulting Fe(III) bacterially re-reduced to Fe(II). Typically, investigations on this electron shuttle mechanism have been performed in an artificial medium. As MLL comprises an elaborate mixture of bacteria, humic materials and organic and inorganic species, additional complexities were evident within the cycle in this study. Bioavailability of the Fe(III) for bacterial reduction, availability of bacterially produced Fe(II) for chemical Cr(VI) reduction and hydrolysis of Fe(II) and Fe(III) become prevalent during each phase of the shuttle cycle when MLL is present. Each of these factors contributes to the overall rate of bacterial Cr(VI) reduction in this media. This work highlights the need to consider local environmental conditions when assessing the bacterial reduction of Cr(VI).","The role of iron in hexavalent chromium reduction by municipal landfill leachate Abs: The function of iron (ferric (Fe(III)) and ferrous (Fe(II))) in the hexavalent chromium (Cr(VI)) reduction mechanism by bacteria in municipal landfill leachate (MLL) was assessed. Evidence of an &quot;electron shuttle&quot; mechanism was observed, whereby the Cr(VI) was reduced to trivalent chromium (Cr(III)) by Fe(II) with the resulting Fe(III) bacterially re-reduced to Fe(II). Typically, investigations on this electron shuttle mechanism have been performed in an artificial medium. As MLL comprises an elaborate mixture of bacteria, humic materials and organic and inorganic species, additional complexities were evident within the cycle in this study. Bioavailability of the Fe(III) for bacterial reduction, availability of bacterially produced Fe(II) for chemical Cr(VI) reduction and hydrolysis of Fe(II) and Fe(III) become prevalent during each phase of the shuttle cycle when MLL is present. Each of these factors contributes to the overall rate of bacterial Cr(VI) reduction in this media. This work highlights the need to consider local environmental conditions when assessing the bacterial reduction of Cr(VI)."
1231693,Zhou et al. 2008,Influence of complex reagents on removal of chromium(VI) by zero-valent iron,"The removal of Cr(VI) by zero-valent iron (Fe(0)) and the effect of three complex reagents, ethylenediaminetetraacetic acid (EDTA), NaF and 1,10-phenanthroline, on this reaction were investigated using batch reactors at pH values of 4, 5 and 6. The results indicate that the removal of Cr(VI) by Fe(0) is slow at pH 5.0 and that three complex reagents play different roles in the reaction. EDTA and NaF significantly enhance the reaction rate. The zero-order rate constants at pH 5.0 were 5.44 microM min(-1) in the presence of 4mM EDTA and 0.99 micrM min(-1) in the presence of 8 mM NaF, respectively, whereas that of control was only 0.33 micrM min(-1), even at pH=4.0. This enhancement is attributed to the formation of complex compounds between EDTA/NaF and reaction products, such as Cr(III) and Fe(III), which eliminate the precipitates of Cr(III), Fe(III) hydroxides and Cr(x)Fe(1-)(x)(OH)(3) and thus reduce surface passivation of Fe(0). In contrast, 1,10-phenanthroline, a complex reagent for Fe(II), dramatically decreases Cr(VI) reduction by Fe(0). At pH=4.0, the zero-order rate constant in the presence of 1mM of 1,10-phenanthroline was 0.02 micrM min(-1), decreasing by 99.7% and 93.9%, respectively, compared with the results in the presence and absence of EDTA. The results suggest that a pathway of the reduction of Cr(VI) to Cr(III) by Fe(0) may involve dissolution of Fe(0) to produce Fe(II), followed by reduction of Cr(VI) by Fe(II), rather than the direct reaction between Cr(VI) and Fe(0), in which Fe(0) transfers electrons to Cr(VI).","Influence of complex reagents on removal of chromium(VI) by zero-valent iron Abs: The removal of Cr(VI) by zero-valent iron (Fe(0)) and the effect of three complex reagents, ethylenediaminetetraacetic acid (EDTA), NaF and 1,10-phenanthroline, on this reaction were investigated using batch reactors at pH values of 4, 5 and 6. The results indicate that the removal of Cr(VI) by Fe(0) is slow at pH 5.0 and that three complex reagents play different roles in the reaction. EDTA and NaF significantly enhance the reaction rate. The zero-order rate constants at pH 5.0 were 5.44 microM min(-1) in the presence of 4mM EDTA and 0.99 micrM min(-1) in the presence of 8 mM NaF, respectively, whereas that of control was only 0.33 micrM min(-1), even at pH=4.0. This enhancement is attributed to the formation of complex compounds between EDTA/NaF and reaction products, such as Cr(III) and Fe(III), which eliminate the precipitates of Cr(III), Fe(III) hydroxides and Cr(x)Fe(1-)(x)(OH)(3) and thus reduce surface passivation of Fe(0). In contrast, 1,10-phenanthroline, a complex reagent for Fe(II), dramatically decreases Cr(VI) reduction by Fe(0). At pH=4.0, the zero-order rate constant in the presence of 1mM of 1,10-phenanthroline was 0.02 micrM min(-1), decreasing by 99.7% and 93.9%, respectively, compared with the results in the presence and absence of EDTA. The results suggest that a pathway of the reduction of Cr(VI) to Cr(III) by Fe(0) may involve dissolution of Fe(0) to produce Fe(II), followed by reduction of Cr(VI) by Fe(II), rather than the direct reaction between Cr(VI) and Fe(0), in which Fe(0) transfers electrons to Cr(VI)."
1231692,Yoon et al. 2009,Application of immobilized nanotubular TiO(2) electrode for photocatalytic hydrogen evolution: reduction of hexavalent chromium (Cr(VI)) in water,"In this study, immobilized TiO(2) electrode is applied to reduce toxic Cr(VI) to non-toxic Cr(III) in aqueous solution under UV irradiation. To overcome the limitation of powder TiO(2), a novel technique of immobilization based on anodization was applied and investigated under various experimental conditions. The anodization was performed at 20V-5 degrees C for 45min with 0.5% hydrofluoric acid, and then the anodized samples were annealed under oxygen stream in the range 450-850 degrees C. Based on the results of the experiments, the photocatalytic Cr(VI) reduction was favorable in acidic conditions, with approximately 98% of the Cr(VI) being reduced within 2h at pH 3. Among the samples tested under same anodizing condition, the nanotubular TiO(2) annealed at 450 and 550 degrees C showed highest reduction efficiencies of Cr(VI). In addition, the surface characterizations (zeta potential, XRD, and SEM) of these samples proved that the Cr(VI) reduction efficiency was higher under acidic conditions and at a lower annealing temperature. From this research, it was concluded that the anodized TiO(2) has the potential to be a useful technology for environmental remediation as well as photocatalytic hydrogen production from water.","Application of immobilized nanotubular TiO(2) electrode for photocatalytic hydrogen evolution: reduction of hexavalent chromium (Cr(VI)) in water Abs: In this study, immobilized TiO(2) electrode is applied to reduce toxic Cr(VI) to non-toxic Cr(III) in aqueous solution under UV irradiation. To overcome the limitation of powder TiO(2), a novel technique of immobilization based on anodization was applied and investigated under various experimental conditions. The anodization was performed at 20V-5 degrees C for 45min with 0.5% hydrofluoric acid, and then the anodized samples were annealed under oxygen stream in the range 450-850 degrees C. Based on the results of the experiments, the photocatalytic Cr(VI) reduction was favorable in acidic conditions, with approximately 98% of the Cr(VI) being reduced within 2h at pH 3. Among the samples tested under same anodizing condition, the nanotubular TiO(2) annealed at 450 and 550 degrees C showed highest reduction efficiencies of Cr(VI). In addition, the surface characterizations (zeta potential, XRD, and SEM) of these samples proved that the Cr(VI) reduction efficiency was higher under acidic conditions and at a lower annealing temperature. From this research, it was concluded that the anodized TiO(2) has the potential to be a useful technology for environmental remediation as well as photocatalytic hydrogen production from water."
1231690,Park et al. 2008,Development of a new Cr(VI)-biosorbent from agricultural biowaste,"Among useless but abundant agricultural biowastes such as banana skin, green tea waste, oak leaf, walnut shell, peanut shell and rice husk, in this study, banana skin was screened as the most efficient biomaterial to remove toxic Cr(VI) from aqueous solution. X-ray photoelectron spectroscopy (XPS) study revealed that the mechanism of Cr(VI) biosorption by banana skin was its complete reduction into Cr(III) in both aqueous and solid phases and partial binding of the reduced-Cr(III), in the range of pH 1.5-4 tested. One gram of banana skin could reduce 249.6 (+/-4.2)mg of Cr(VI) at initial pH 1.5. Namely, Cr(VI)-reducing capacity of banana skin was four times higher than that of a common chemical Cr(VI)-reductant, FeSO(4).7H(2)O. To diminish undesirable/serious organic leaching from the biomaterial and to enhance removal efficiency of total Cr, its powder was immobilized within Ca-alginate bead. The developed Cr(VI)-biosorbent could completely reduce toxic Cr(VI) to less toxic Cr(III) and could remove almost of the reduced-Cr(III) from aqueous phase. On the basis of removal mechanisms of Cr(VI) and total Cr by the Cr(VI)-biosorbent, a kinetic model was derived and could be successfully used to predict their removal behaviors in aqueous phase. In conclusion, our Cr(VI)-biosorbent must be a potent candidate to substitute for chemical reductants as well as adsorbents for treating Cr(VI)-bearing wastewaters.","Development of a new Cr(VI)-biosorbent from agricultural biowaste Abs: Among useless but abundant agricultural biowastes such as banana skin, green tea waste, oak leaf, walnut shell, peanut shell and rice husk, in this study, banana skin was screened as the most efficient biomaterial to remove toxic Cr(VI) from aqueous solution. X-ray photoelectron spectroscopy (XPS) study revealed that the mechanism of Cr(VI) biosorption by banana skin was its complete reduction into Cr(III) in both aqueous and solid phases and partial binding of the reduced-Cr(III), in the range of pH 1.5-4 tested. One gram of banana skin could reduce 249.6 (+/-4.2)mg of Cr(VI) at initial pH 1.5. Namely, Cr(VI)-reducing capacity of banana skin was four times higher than that of a common chemical Cr(VI)-reductant, FeSO(4).7H(2)O. To diminish undesirable/serious organic leaching from the biomaterial and to enhance removal efficiency of total Cr, its powder was immobilized within Ca-alginate bead. The developed Cr(VI)-biosorbent could completely reduce toxic Cr(VI) to less toxic Cr(III) and could remove almost of the reduced-Cr(III) from aqueous phase. On the basis of removal mechanisms of Cr(VI) and total Cr by the Cr(VI)-biosorbent, a kinetic model was derived and could be successfully used to predict their removal behaviors in aqueous phase. In conclusion, our Cr(VI)-biosorbent must be a potent candidate to substitute for chemical reductants as well as adsorbents for treating Cr(VI)-bearing wastewaters."
1231688,Bo?gelmez et al. 2008,The protective and antidotal effects of taurine on hexavalent chromium-induced oxidative stress in mice liver tissue,"Acute exposure to hexavalent chromium [Cr(VI)] compounds can cause hepatotoxicity. Reactive intermediates and free radicals generated during reduction process may be responsible for Cr(VI) toxicity. In this study, the effects of pretreatment or posttreatment of taurine on Cr(VI)-induced oxidative stress and chromium accumulation in liver tissue of Swiss Albino mice were investigated. Single intraperitoneal (ip) potassium dichromate treatment (20 mgCr/kg), as Cr(VI) compound, significantly elevated the level of lipid peroxidation as compared with control group (p &lt; 0.05). This was accompanied by significant decreases in nonprotein sulfhydryls (NPSHs) level, superoxide dismutase (SOD), and catalase (CAT) enzyme activities as well as a significant chromium accumulation in the tissue (p &lt; 0.05). Taurine administration (1 g/kg, ip) before or after Cr(VI) exposure resulted in reduction of lipid peroxidation (p &lt; 0.05) showed rebalancing effect on tissue NPSH levels either in pretreatment or in posttreatment (p &lt; 0.05). Enzyme activities of SOD and CAT were restored by taurine pretreatment (p &lt; 0.05), whereas posttreatment had less pronounced effects on these parameters. On the other hand, taurine treatment, before or after exposure, could exert only slight decreases in tissue Cr levels (p &gt; 0.05). In view of the results, taurine seems to exert some beneficial effects against Cr(VI)-induced oxidative stress in liver tissue.","The protective and antidotal effects of taurine on hexavalent chromium-induced oxidative stress in mice liver tissue Abs: Acute exposure to hexavalent chromium [Cr(VI)] compounds can cause hepatotoxicity. Reactive intermediates and free radicals generated during reduction process may be responsible for Cr(VI) toxicity. In this study, the effects of pretreatment or posttreatment of taurine on Cr(VI)-induced oxidative stress and chromium accumulation in liver tissue of Swiss Albino mice were investigated. Single intraperitoneal (ip) potassium dichromate treatment (20 mgCr/kg), as Cr(VI) compound, significantly elevated the level of lipid peroxidation as compared with control group (p &lt; 0.05). This was accompanied by significant decreases in nonprotein sulfhydryls (NPSHs) level, superoxide dismutase (SOD), and catalase (CAT) enzyme activities as well as a significant chromium accumulation in the tissue (p &lt; 0.05). Taurine administration (1 g/kg, ip) before or after Cr(VI) exposure resulted in reduction of lipid peroxidation (p &lt; 0.05) showed rebalancing effect on tissue NPSH levels either in pretreatment or in posttreatment (p &lt; 0.05). Enzyme activities of SOD and CAT were restored by taurine pretreatment (p &lt; 0.05), whereas posttreatment had less pronounced effects on these parameters. On the other hand, taurine treatment, before or after exposure, could exert only slight decreases in tissue Cr levels (p &gt; 0.05). In view of the results, taurine seems to exert some beneficial effects against Cr(VI)-induced oxidative stress in liver tissue."
1231687,Kalayarasan et al. 2008,Chromium (VI)-induced oxidative stress and apoptosis is reduced by garlic and its derivative S-allylcysteine through the activation of Nrf2 in the hepatocytes of Wistar rats,"Chromium (VI) compounds are genotoxic and carcinogenic in a variety of experimental systems. Garlic and its derivatives possess antioxidant properties to scavenge the toxic radicals. The mechanism by which garlic induces the antioxidant and phase II enzymes during oxidative stress-induced apoptosis is not known. This study aims to evaluate the protective role of aqueous garlic extract (AGE; 200 mg kg(-1) b.w.) and S-allylcysteine (SAC; 100 mg kg(-1) b.w.) on potassium dichromate-induced apoptosis and oxidative stress in the hepatocytes of Wistar rats. Activities of liver marker enzymes such as aspartate transaminase, alanine transaminase and lactate dehydrogenase were found to be increased in the serum of chromium-induced group, whereas administration of garlic extract and SAC restored the enzymes to near normal status. The activities of enzymic antioxidants (superoxide dismutase, catalase, glutathione peroxidase), non-enzymic antioxidants (vitamin C and vitamin E) and the levels of reduced glutathione were found to be decreased, while an increase in lipid peroxidation (LPO) and reactive oxygen species were observed in the liver tissues of chromium-induced group. Administration of AGE and SAC reversed the status of these parameters substantially. Histological and transmission electron microscopic studies support our findings. Confocal microscopic analysis using annexin-V showed the involvement of apoptosis. Further, the expression of a novel transcription factor, nuclear factor-E2 related factor 2 (Nrf2) was investigated using Immunofluorescence and Western blotting. The results show the promising role of Nrf2-mediated antioxidant defense of AGE and SAC against chromium toxicity.","Chromium (VI)-induced oxidative stress and apoptosis is reduced by garlic and its derivative S-allylcysteine through the activation of Nrf2 in the hepatocytes of Wistar rats Abs: Chromium (VI) compounds are genotoxic and carcinogenic in a variety of experimental systems. Garlic and its derivatives possess antioxidant properties to scavenge the toxic radicals. The mechanism by which garlic induces the antioxidant and phase II enzymes during oxidative stress-induced apoptosis is not known. This study aims to evaluate the protective role of aqueous garlic extract (AGE; 200 mg kg(-1) b.w.) and S-allylcysteine (SAC; 100 mg kg(-1) b.w.) on potassium dichromate-induced apoptosis and oxidative stress in the hepatocytes of Wistar rats. Activities of liver marker enzymes such as aspartate transaminase, alanine transaminase and lactate dehydrogenase were found to be increased in the serum of chromium-induced group, whereas administration of garlic extract and SAC restored the enzymes to near normal status. The activities of enzymic antioxidants (superoxide dismutase, catalase, glutathione peroxidase), non-enzymic antioxidants (vitamin C and vitamin E) and the levels of reduced glutathione were found to be decreased, while an increase in lipid peroxidation (LPO) and reactive oxygen species were observed in the liver tissues of chromium-induced group. Administration of AGE and SAC reversed the status of these parameters substantially. Histological and transmission electron microscopic studies support our findings. Confocal microscopic analysis using annexin-V showed the involvement of apoptosis. Further, the expression of a novel transcription factor, nuclear factor-E2 related factor 2 (Nrf2) was investigated using Immunofluorescence and Western blotting. The results show the promising role of Nrf2-mediated antioxidant defense of AGE and SAC against chromium toxicity."
1231686,Massara et al. 2008,"Hexavalent chromium removal by viable, granular anaerobic biomass","Hexavalent chromium in industrial wastewater is a major concern due to its extreme toxicity. This study investigates the removal of Cr(VI) using viable anaerobic granular biomass as a biosorbent. The effect of Cr(VI) concentration on biogas content and COD removal using batch studies indicated that the phase II (methanogenic-rich) culture was more sensitive than the phase I (acidogenic-rich) culture. Toxicity indices for both cultures using COD removal were developed based on linear-log interpolation. The median inhibition Cr(VI) concentration (IC(50)), for phase II cultures was found to be 263mg/L, while that for phase I cultures was 309mg/L. A sorption study was conducted on viable and non-viable (dried) phase I-rich biomass: both followed the Langmuir model. In addition, the biosorption capacity for metabolically inhibited biomass was 25% less indicating some level of cellular uptake associated with Cr(VI) removal. This study demonstrated the potential for a two-phase anaerobic treatment system for a Cr(VI)-contaminated effluent.","Hexavalent chromium removal by viable, granular anaerobic biomass Abs: Hexavalent chromium in industrial wastewater is a major concern due to its extreme toxicity. This study investigates the removal of Cr(VI) using viable anaerobic granular biomass as a biosorbent. The effect of Cr(VI) concentration on biogas content and COD removal using batch studies indicated that the phase II (methanogenic-rich) culture was more sensitive than the phase I (acidogenic-rich) culture. Toxicity indices for both cultures using COD removal were developed based on linear-log interpolation. The median inhibition Cr(VI) concentration (IC(50)), for phase II cultures was found to be 263mg/L, while that for phase I cultures was 309mg/L. A sorption study was conducted on viable and non-viable (dried) phase I-rich biomass: both followed the Langmuir model. In addition, the biosorption capacity for metabolically inhibited biomass was 25% less indicating some level of cellular uptake associated with Cr(VI) removal. This study demonstrated the potential for a two-phase anaerobic treatment system for a Cr(VI)-contaminated effluent."
1231685,Tsai and  Chen 2008,Voltammetric study and electrochemical detection of hexavalent chromium at gold nanoparticle-electrodeposited indium tinoxide (ITO) electrodes in acidic media,"The voltammetric behavior of hexavalent chromium species (Cr(VI)) was respectively studied at ITO, bulk Au, and Au-electrodeposited electrodes in 0.01 M NaCl aqueous solutions containing 0.01 M HCl. It was found that performance degradation of the ITO electrodes toward the reduction of Cr(VI) can be suppressed by modifying the electrode surface with gold nanoparticles (AuNPs), which were formed on ITO electrodes by potential-sweeping or potential-step electrodeposition in a 0.01 M Na(2)SO(4) solution containing 1 mM HAuCl(4) x 3 H(2)O and 0.01 M H(2)SO(4). After the modification, the surface of ITO electrodes turned to the characteristically red or blue color exhibited by AuNPs. The gold nanoparticle-electrodeposited indium-tinoxide electrode (AuNP-ITO) demonstrates unique catalytic behavior, higher sensitivity and stability in the reduction of Cr(VI). Cr(VI) species was detected by either cyclic voltammetry or hydrodynamic amperometry. By cyclic voltammetry, the dependence of cathodic peak current on concentration was linear from 5 to 100 microM with a detection limit of 2 microM (sigma=3), and linearity was obtained from 0.5 to 50 microM by hydrodynamic amperometry where a constant potential of +0.2V (vs. Ag/AgCl) was applied and a batch-injection cell was employed. For hydrodynamic amperometry, the detection limit was 0.1 microM (sigma=3).","Voltammetric study and electrochemical detection of hexavalent chromium at gold nanoparticle-electrodeposited indium tinoxide (ITO) electrodes in acidic media Abs: The voltammetric behavior of hexavalent chromium species (Cr(VI)) was respectively studied at ITO, bulk Au, and Au-electrodeposited electrodes in 0.01 M NaCl aqueous solutions containing 0.01 M HCl. It was found that performance degradation of the ITO electrodes toward the reduction of Cr(VI) can be suppressed by modifying the electrode surface with gold nanoparticles (AuNPs), which were formed on ITO electrodes by potential-sweeping or potential-step electrodeposition in a 0.01 M Na(2)SO(4) solution containing 1 mM HAuCl(4) x 3 H(2)O and 0.01 M H(2)SO(4). After the modification, the surface of ITO electrodes turned to the characteristically red or blue color exhibited by AuNPs. The gold nanoparticle-electrodeposited indium-tinoxide electrode (AuNP-ITO) demonstrates unique catalytic behavior, higher sensitivity and stability in the reduction of Cr(VI). Cr(VI) species was detected by either cyclic voltammetry or hydrodynamic amperometry. By cyclic voltammetry, the dependence of cathodic peak current on concentration was linear from 5 to 100 microM with a detection limit of 2 microM (sigma=3), and linearity was obtained from 0.5 to 50 microM by hydrodynamic amperometry where a constant potential of +0.2V (vs. Ag/AgCl) was applied and a batch-injection cell was employed. For hydrodynamic amperometry, the detection limit was 0.1 microM (sigma=3)."
1231684,Banu et al. 2008,"Lactational exposure to hexavalent chromium delays puberty by impairing ovarian development, steroidogenesis and pituitary hormone synthesis in developing Wistar rats","Hexavalent chromium (Cr-VI) is used in a wide range of industries. Cr-VI from chromate industries and atmospheric emissions contribute to the Cr contamination in the environment. Cr is a reproductive metal toxicant that can traverse the placental barrier and cause a wide range of fetal effects including ovotoxicity. Therefore, the goal of this study was to investigate the basic mechanisms involved in Cr(VI)-induced ovotoxicity, and the protective role of vitamin C on ovarian follicular development and function in Cr(VI)-induced reproductive toxicity using both in vivo and in vitro approaches. Lactating rats received potassium dichromate (200 mg/L) with or without vitamin C (500 mg/L), through drinking water from postpartum days 1-21. During postnatal days (PND) 1-21 the pups received Cr(VI) via the mother's milk. Pups from both control and treatment groups were continued on regular diet and water from PND-21 onwards, and euthanized on PND-21, -45 and -65. Cr(VI) decreased steroidogenesis, GH and PRL, increased FSH and did not alter LH. Cr(VI) delayed puberty, decreased follicle number, and extended estrous cycle. Spontaneously immortalized rat granulosa cells were treated with 12.5 microM (IC(50)) potassium dichromate for 12 and 24 h, with or without vitamin C pre-treatment. Cr(VI) decreased the mRNA expressions of StAR, SF-1, 17beta-HSD-1, 17beta-HSD-2, FSHR, LHR, ER alpha and ER beta. Vitamin C pre-treatment protected ovary and granulosa cells from the deleterious effects of Cr(VI) toxicity, both in vivo and in vitro. Therefore, Cr(VI) toxicity could be a potential risk to the reproductive system in developing females, and vitamin C plays a protective role against Cr(VI)-induced ovotoxicity.","Lactational exposure to hexavalent chromium delays puberty by impairing ovarian development, steroidogenesis and pituitary hormone synthesis in developing Wistar rats Abs: Hexavalent chromium (Cr-VI) is used in a wide range of industries. Cr-VI from chromate industries and atmospheric emissions contribute to the Cr contamination in the environment. Cr is a reproductive metal toxicant that can traverse the placental barrier and cause a wide range of fetal effects including ovotoxicity. Therefore, the goal of this study was to investigate the basic mechanisms involved in Cr(VI)-induced ovotoxicity, and the protective role of vitamin C on ovarian follicular development and function in Cr(VI)-induced reproductive toxicity using both in vivo and in vitro approaches. Lactating rats received potassium dichromate (200 mg/L) with or without vitamin C (500 mg/L), through drinking water from postpartum days 1-21. During postnatal days (PND) 1-21 the pups received Cr(VI) via the mother's milk. Pups from both control and treatment groups were continued on regular diet and water from PND-21 onwards, and euthanized on PND-21, -45 and -65. Cr(VI) decreased steroidogenesis, GH and PRL, increased FSH and did not alter LH. Cr(VI) delayed puberty, decreased follicle number, and extended estrous cycle. Spontaneously immortalized rat granulosa cells were treated with 12.5 microM (IC(50)) potassium dichromate for 12 and 24 h, with or without vitamin C pre-treatment. Cr(VI) decreased the mRNA expressions of StAR, SF-1, 17beta-HSD-1, 17beta-HSD-2, FSHR, LHR, ER alpha and ER beta. Vitamin C pre-treatment protected ovary and granulosa cells from the deleterious effects of Cr(VI) toxicity, both in vivo and in vitro. Therefore, Cr(VI) toxicity could be a potential risk to the reproductive system in developing females, and vitamin C plays a protective role against Cr(VI)-induced ovotoxicity."
1231683,Kimura et al. 2008,Chromium(VI) inhibits mouse metallothionein-I gene transcription by preventing the zinc-dependent formation of an MTF-1-p300 complex,"Mouse MT-I (metallothionein-I) transcription is regulated by MTF-1 (metal-response-element-binding transcription factor-1) which is recruited to the promoter in response to zinc. Cr(VI) [chromium(VI)] pretreatment blocks zinc-activation of the endogenous MT-I gene and attenuates zinc-activation of MT-I-promoter-driven luciferase reporter genes in transient transfection assays. Chromatin immunoprecipitation assays revealed that Cr(VI) only modestly reduces recruitment of MTF-1 to the MT-I promoter in response to zinc, but drastically reduces the recruitment of RNA polymerase II. These results suggest that Cr(VI) inhibits the ability of MTF-1 to transactivate this gene in response to zinc. Zinc has recently been shown to induce the formation of a co-activator complex containing MTF-1 and the histone acetyltransferase p300 which plays an essential role in the activation of MT-I transcription. In the present study, co-immunoprecipitation assays demonstrated that Cr(VI) pretreatment blocks the zinc-induced formation of this co-activator complex. Thus Cr(VI) inhibits mouse MT-I gene expression in response to zinc by interfering with the ability of MTF-1 to form a co-activator complex containing p300 and recruiting RNA polymerase II to the promoter.","Chromium(VI) inhibits mouse metallothionein-I gene transcription by preventing the zinc-dependent formation of an MTF-1-p300 complex Abs: Mouse MT-I (metallothionein-I) transcription is regulated by MTF-1 (metal-response-element-binding transcription factor-1) which is recruited to the promoter in response to zinc. Cr(VI) [chromium(VI)] pretreatment blocks zinc-activation of the endogenous MT-I gene and attenuates zinc-activation of MT-I-promoter-driven luciferase reporter genes in transient transfection assays. Chromatin immunoprecipitation assays revealed that Cr(VI) only modestly reduces recruitment of MTF-1 to the MT-I promoter in response to zinc, but drastically reduces the recruitment of RNA polymerase II. These results suggest that Cr(VI) inhibits the ability of MTF-1 to transactivate this gene in response to zinc. Zinc has recently been shown to induce the formation of a co-activator complex containing MTF-1 and the histone acetyltransferase p300 which plays an essential role in the activation of MT-I transcription. In the present study, co-immunoprecipitation assays demonstrated that Cr(VI) pretreatment blocks the zinc-induced formation of this co-activator complex. Thus Cr(VI) inhibits mouse MT-I gene expression in response to zinc by interfering with the ability of MTF-1 to form a co-activator complex containing p300 and recruiting RNA polymerase II to the promoter."
1231681,Boyle and  Kakouli-Duarte 2008,The effects of chromium VI on the fitness and on the beta-tubulin genes during in vivo development of the nematode Steinernema feltiae,"The entomopathogenic nematode (EPN), Steinernema feltiae, is a commonly occurring nematode in the soil in Ireland. Consequently, we have conducted investigations as to the utility of this species as a candidate organism for the detection of chromium in Irish soils. These experiments have demonstrated that S. feltiae can survive and reproduce in the presence of high concentrations of chromium VI. It was observed that concentrations as high as 1000 ppm have little effect on the ability of this organism to produce large numbers of progeny. Nematodes were not observed to reproduce above 1800 ppm. However, an increase in development times for the nematode in vivo was noted at concentrations of 400 ppm upwards. This paper also illustrates the effects upon the beta-tubulin genes within nematode populations exposed to chromium VI in vivo. DNA sequencing has shown that elevated levels of variations occur among the population treatments, although these variations do not appear to be dependent upon chromium concentration. These findings constitute this organism appropriate for further investigation for the development of sub-lethal end points and biomarkers for the detection and biomonitoring of chromium VI contamination in soil.","The effects of chromium VI on the fitness and on the beta-tubulin genes during in vivo development of the nematode Steinernema feltiae Abs: The entomopathogenic nematode (EPN), Steinernema feltiae, is a commonly occurring nematode in the soil in Ireland. Consequently, we have conducted investigations as to the utility of this species as a candidate organism for the detection of chromium in Irish soils. These experiments have demonstrated that S. feltiae can survive and reproduce in the presence of high concentrations of chromium VI. It was observed that concentrations as high as 1000 ppm have little effect on the ability of this organism to produce large numbers of progeny. Nematodes were not observed to reproduce above 1800 ppm. However, an increase in development times for the nematode in vivo was noted at concentrations of 400 ppm upwards. This paper also illustrates the effects upon the beta-tubulin genes within nematode populations exposed to chromium VI in vivo. DNA sequencing has shown that elevated levels of variations occur among the population treatments, although these variations do not appear to be dependent upon chromium concentration. These findings constitute this organism appropriate for further investigation for the development of sub-lethal end points and biomarkers for the detection and biomonitoring of chromium VI contamination in soil."
1231679,Samaras et al. 2009,Effect of hexavalent chromium on the activated sludge process and on the sludge protozoan community,"The objectives of this study were the determination of chromium effects to the performance of an activated sludge unit and the investigation of the response of the activated sludge protozoan community to Cr(VI). Two bench scale activated sludge reactors were supplied with synthetic sewage containing Cr(VI), at concentrations from 1 up to 50 mg L(-1). Protozoan species were identified and were related to the system efficiency. Variations in the abundance and diversity of the protozoan species were observed under various chromium concentrations. High removal rates of organics and nutrients were observed after the acclimatization of the activated sludge, which were related to the initial chromium(VI) concentration. Chromium(VI) removal efficiency was high in all cases. The protistan community was affected by the influent chromium content. Dominance of sessile species was observed in the reactor receiving 5 mg L(-1) influent chromium, whereas co-dominance of sessile and carnivorous species was observed in the reactors receiving higher chromium concentrations.","Effect of hexavalent chromium on the activated sludge process and on the sludge protozoan community Abs: The objectives of this study were the determination of chromium effects to the performance of an activated sludge unit and the investigation of the response of the activated sludge protozoan community to Cr(VI). Two bench scale activated sludge reactors were supplied with synthetic sewage containing Cr(VI), at concentrations from 1 up to 50 mg L(-1). Protozoan species were identified and were related to the system efficiency. Variations in the abundance and diversity of the protozoan species were observed under various chromium concentrations. High removal rates of organics and nutrients were observed after the acclimatization of the activated sludge, which were related to the initial chromium(VI) concentration. Chromium(VI) removal efficiency was high in all cases. The protistan community was affected by the influent chromium content. Dominance of sessile species was observed in the reactor receiving 5 mg L(-1) influent chromium, whereas co-dominance of sessile and carnivorous species was observed in the reactors receiving higher chromium concentrations."
1231677,Gupta and  Rastogi 2009,Biosorption of hexavalent chromium by raw and acid-treated green alga Oedogonium hatei from aqueous solutions,"The hexavalent chromium, Cr(VI), biosorption by raw and acid-treated Oedogonium hatei were studied from aqueous solutions. Batch experiments were conducted to determine the biosorption properties of the biomass. The optimum conditions of biosorption were found to be: a biomass dose of 0.8 g/L, contact time of 110 min, pH and temperature 2.0 and 318 K respectively. Both Langmuir and Freundlich isotherm equations could fit the equilibrium data. Under the optimal conditions, the biosorption capacities of the raw and acid-treated algae were 31 and 35.2 mg Cr(VI) per g of dry adsorbent, respectively. Thermodynamic parameters showed that the adsorption of Cr(VI) onto algal biomass was feasible, spontaneous and endothermic under studied conditions. The pseudo-first-order kinetic model adequately describe the kinetic data in comparison to second-order model and the process involving rate-controlling step is much complex involving both boundary layer and intra-particle diffusion processes. The physical and chemical properties of the biosorbent were determined and the nature of biomass-metal ions interactions were evaluated by FTIR analysis, which showed the participation of -COOH, -OH and -NH(2) groups in the biosorption process. Biosorbents could be regenerated using 0.1 M NaOH solution, with up to 75% recovery. Thus, the biomass used in this work proved to be effective materials for the treatment of chromium bearing aqueous solutions.","Biosorption of hexavalent chromium by raw and acid-treated green alga Oedogonium hatei from aqueous solutions Abs: The hexavalent chromium, Cr(VI), biosorption by raw and acid-treated Oedogonium hatei were studied from aqueous solutions. Batch experiments were conducted to determine the biosorption properties of the biomass. The optimum conditions of biosorption were found to be: a biomass dose of 0.8 g/L, contact time of 110 min, pH and temperature 2.0 and 318 K respectively. Both Langmuir and Freundlich isotherm equations could fit the equilibrium data. Under the optimal conditions, the biosorption capacities of the raw and acid-treated algae were 31 and 35.2 mg Cr(VI) per g of dry adsorbent, respectively. Thermodynamic parameters showed that the adsorption of Cr(VI) onto algal biomass was feasible, spontaneous and endothermic under studied conditions. The pseudo-first-order kinetic model adequately describe the kinetic data in comparison to second-order model and the process involving rate-controlling step is much complex involving both boundary layer and intra-particle diffusion processes. The physical and chemical properties of the biosorbent were determined and the nature of biomass-metal ions interactions were evaluated by FTIR analysis, which showed the participation of -COOH, -OH and -NH(2) groups in the biosorption process. Biosorbents could be regenerated using 0.1 M NaOH solution, with up to 75% recovery. Thus, the biomass used in this work proved to be effective materials for the treatment of chromium bearing aqueous solutions."
1231675,de La Paz Gómez-Díaz and  Martínez-Jerónimo 2009,Modification of the acute toxic response of Daphnia magna Straus 1820 to Cr(VI) by the effect of varying saline concentrations (NaCl),"Daphnia magna Straus is a freshwater organism that can strive in environments with a salinity of up to 12 psu, although its life cycle and survival are significantly affected by increasing salinities. Saline environments are not devoid of chemical contaminant influences, such as toxic metals; for freshwater species this could be another stress factor aside from that caused by salinity. In this study, we assessed the acute (48 h) toxicity produced by hexavalent chromium [Cr(VI)] in neonates of a D. magna strain previously acclimated to different salinities induced by adding NaCl to reconstituted hard water. The Mean Lethal Concentration (CL(50)) values determined for Cr(VI) were 0.14 +/- 0.12, 1.35 +/- 0.34, 1.79 +/- 0.41, 2.0 +/- 0.21, 2.02 +/- 0.075, and 2.6 +/- 0.23 mg l(-1) for salinities of 0.3, 1, 2, 3, 4, and 5 psu, respectively, evidencing that D. magna's sensitivity to Cr(VI) decreased with increasing salinity. The increase in tolerance could be due to a possible antagonic effect of NaCl on Cr(VI) rather than due to a reduction in Cr(VI) bioavailability due to the NaCl concentration. Although it was not demonstrated that the stress produced by salinity increased the sensitivity to the exposed toxicant, care must be exerted in inferring that the impact of contaminants, such as toxic metals, could be lower on freshwater species that sporadically or permanently strive in brackish water environments.","Modification of the acute toxic response of Daphnia magna Straus 1820 to Cr(VI) by the effect of varying saline concentrations (NaCl) Abs: Daphnia magna Straus is a freshwater organism that can strive in environments with a salinity of up to 12 psu, although its life cycle and survival are significantly affected by increasing salinities. Saline environments are not devoid of chemical contaminant influences, such as toxic metals; for freshwater species this could be another stress factor aside from that caused by salinity. In this study, we assessed the acute (48 h) toxicity produced by hexavalent chromium [Cr(VI)] in neonates of a D. magna strain previously acclimated to different salinities induced by adding NaCl to reconstituted hard water. The Mean Lethal Concentration (CL(50)) values determined for Cr(VI) were 0.14 +/- 0.12, 1.35 +/- 0.34, 1.79 +/- 0.41, 2.0 +/- 0.21, 2.02 +/- 0.075, and 2.6 +/- 0.23 mg l(-1) for salinities of 0.3, 1, 2, 3, 4, and 5 psu, respectively, evidencing that D. magna's sensitivity to Cr(VI) decreased with increasing salinity. The increase in tolerance could be due to a possible antagonic effect of NaCl on Cr(VI) rather than due to a reduction in Cr(VI) bioavailability due to the NaCl concentration. Although it was not demonstrated that the stress produced by salinity increased the sensitivity to the exposed toxicant, care must be exerted in inferring that the impact of contaminants, such as toxic metals, could be lower on freshwater species that sporadically or permanently strive in brackish water environments."
1231673,Poopal and  Laxman 2009,Chromate reduction by PVA-alginate immobilized Streptomyces griseus in a bioreactor,"Microbial reduction of toxic Cr6+ to the less toxic Cr3+ is potentially a useful bioremediation process. Among the matrices tested for whole cell immobilization of an efficient chromate-reducing Streptomyces griseus strain, PVA-alginate was the most effective and was used for reduction of Cr(VI) in a bioreactor. Cr6+ reduction efficiency decreased as Cr6+ was increased from 2 to 12 mg l(-1) but increased with an increase in biomass concentration. However, increasing the flow rate from 2 to 8 ml h(-1) did not significantly affect Cr(6+) reduction. The reduction was faster in simulated effluent than in synthetic medium and complete removal of 8 mg Cr6+ l(-1) from effluent and synthetic medium occurred in 2 and 12 h, respectively. Our results indicate that immobilized S. griseus cells could be applied for the large-scale bioremediation of chromate-containing effluents and wastewaters.","Chromate reduction by PVA-alginate immobilized Streptomyces griseus in a bioreactor Abs: Microbial reduction of toxic Cr6+ to the less toxic Cr3+ is potentially a useful bioremediation process. Among the matrices tested for whole cell immobilization of an efficient chromate-reducing Streptomyces griseus strain, PVA-alginate was the most effective and was used for reduction of Cr(VI) in a bioreactor. Cr6+ reduction efficiency decreased as Cr6+ was increased from 2 to 12 mg l(-1) but increased with an increase in biomass concentration. However, increasing the flow rate from 2 to 8 ml h(-1) did not significantly affect Cr(6+) reduction. The reduction was faster in simulated effluent than in synthetic medium and complete removal of 8 mg Cr6+ l(-1) from effluent and synthetic medium occurred in 2 and 12 h, respectively. Our results indicate that immobilized S. griseus cells could be applied for the large-scale bioremediation of chromate-containing effluents and wastewaters."
1231672,Jo et al. 2008,Iron monosulfide as a scavenger for dissolved hexavalent chromium and cadmium,"Iron sulfide minerals are common components of soil/sedimentary environments. Reactions near the surfaces of iron sulfides play important roles in metal retention, mobility, and bioavailability. A series of batch experiments was conducted to study the removal of aqueous chromium and cadmium by iron monosulfide. Hexavalent chromium was reduced to Cr(III) by iron monosulfide with simultaneous precipitation of chromium and iron oxyhydroxide. In contrast to chromium, the primary retention mechanism of cadmium by iron monosulfide was lattice exchange. Surface adsorption to iron monosulfide and precipitation with sulfide on the iron monosulfide surface also contributed to the removal of aqueous cadmium. New phases of both chromium and cadmium were confirmed with transmission electron microscopy. The solution pH was an important factor in this research; it can change particle surface charge and metal species, hence affecting the removal of chromium, but not cadmium. Ferrous ions without FeS exhibited less Cr(VI) removal than with FeS, which might be owing to sulfides from FeS and the existence of the solid phase. Iron monosulfide exhibited higher removal efficiency for chromium and cadmium than zero valent iron and other iron oxide minerals, and the synergistic effect of ferrous iron and sulfide appeared to cause this result.","Iron monosulfide as a scavenger for dissolved hexavalent chromium and cadmium Abs: Iron sulfide minerals are common components of soil/sedimentary environments. Reactions near the surfaces of iron sulfides play important roles in metal retention, mobility, and bioavailability. A series of batch experiments was conducted to study the removal of aqueous chromium and cadmium by iron monosulfide. Hexavalent chromium was reduced to Cr(III) by iron monosulfide with simultaneous precipitation of chromium and iron oxyhydroxide. In contrast to chromium, the primary retention mechanism of cadmium by iron monosulfide was lattice exchange. Surface adsorption to iron monosulfide and precipitation with sulfide on the iron monosulfide surface also contributed to the removal of aqueous cadmium. New phases of both chromium and cadmium were confirmed with transmission electron microscopy. The solution pH was an important factor in this research; it can change particle surface charge and metal species, hence affecting the removal of chromium, but not cadmium. Ferrous ions without FeS exhibited less Cr(VI) removal than with FeS, which might be owing to sulfides from FeS and the existence of the solid phase. Iron monosulfide exhibited higher removal efficiency for chromium and cadmium than zero valent iron and other iron oxide minerals, and the synergistic effect of ferrous iron and sulfide appeared to cause this result."
1231671,Caglieri et al. 2008,Exposure to low levels of hexavalent chromium: target doses and comparative effects on two human pulmonary cell lines,"Intracellular reduction of hexavalent chromium [Cr(VI)] is associated with the production of reactive oxygen species (ROS) and subsequent oxidative damage to different intracellular molecules like DNA, proteins and lipids is believed to contribute to the process of carcinogenesis. Aim of this study was to develop a model to establish a relationship between intracellular and macromolecule-bound chromium and some biomarkers of oxidative stress in two in vitro cell lines. Human lung adenocarcinoma (A549) and human bronchial epithelial (BEAS2B) cells were exposed for 3, 8 and 24 hours to relatively low doses (0.5--1--2 microM) of Cr(VI), i.e., to concentrations similar to what measured and reported by some authors in unexposed subjects and chromate workers. The results show that the differential cytotoxicity of Cr(VI) on the A549 and BEAS2B cell lines may be related both to their different polymorphism of Glutathione S-transferases genes and probably to their unlike permeability to Cr(VI). The glutathione decrease and the induction of HO-1 observed only in BEAS2B cells after Cr(VI) exposure strengthen the idea that glutathione S-transferases activity may accelerate the reduction of Cr(VI) to Cr(III) with the concomitant induction of oxidative stress. In conclusion, the determination of intracellular Cr in cellular models can be considered an important step in comparing in vitro and in vivo models on the basis of target doses and a promising approach to study the effects of pneumotoxic compounds.","Exposure to low levels of hexavalent chromium: target doses and comparative effects on two human pulmonary cell lines Abs: Intracellular reduction of hexavalent chromium [Cr(VI)] is associated with the production of reactive oxygen species (ROS) and subsequent oxidative damage to different intracellular molecules like DNA, proteins and lipids is believed to contribute to the process of carcinogenesis. Aim of this study was to develop a model to establish a relationship between intracellular and macromolecule-bound chromium and some biomarkers of oxidative stress in two in vitro cell lines. Human lung adenocarcinoma (A549) and human bronchial epithelial (BEAS2B) cells were exposed for 3, 8 and 24 hours to relatively low doses (0.5--1--2 microM) of Cr(VI), i.e., to concentrations similar to what measured and reported by some authors in unexposed subjects and chromate workers. The results show that the differential cytotoxicity of Cr(VI) on the A549 and BEAS2B cell lines may be related both to their different polymorphism of Glutathione S-transferases genes and probably to their unlike permeability to Cr(VI). The glutathione decrease and the induction of HO-1 observed only in BEAS2B cells after Cr(VI) exposure strengthen the idea that glutathione S-transferases activity may accelerate the reduction of Cr(VI) to Cr(III) with the concomitant induction of oxidative stress. In conclusion, the determination of intracellular Cr in cellular models can be considered an important step in comparing in vitro and in vivo models on the basis of target doses and a promising approach to study the effects of pneumotoxic compounds."
1231670,Amuda et al. 2009,Kinetics and equilibrium studies of adsorption of chromium(VI) ion from industrial wastewater using Chrysophyllum albidum (Sapotaceae) seed shells,"A new biosorbent has been prepared by coating Chrysophyllum albidum (Sapotaceae) seed shells with chitosan and/or oxidizing agents such as sulfuric acid. This study investigated the technical feasibility of activated and modified activated C. albidum seed shells carbons for the adsorption of chromium(VI) from aqueous solution. The sorption process with respect to its equilibria and kinetics as well as the effects of pH, contact time, adsorbent mass, adsorbate concentration and particle size on adsorption was also studied. The most effective pH range was found to be between 4.5 and 5 for the sorption of the metal ion. The pseudo-first-order rate equation by Lagergren and pseudo-second-order rate equation were tested on the kinetic data, the adsorption process followed pseudo-second-order rate kinetics, also, isotherm data was analyzed for possible agreement with the Langmuir and Freundlich adsorption isotherms, the Freundlich and Langmuir models for dynamics of metal ion uptake proposed in this work fitted the experimental data reasonably well. However, equilibrium sorption data were better represented by Langmuir model than Freundlich. The adsorption capacity calculated from Langmuir isotherm was 84.31, 76.23 and 59.63mgCr(VI)/g at initial pH of 3.0 at 30 degrees C for the particle size of 1.00-1.25mm with the use of 12.5, 16.5 and 2.1g/L of CACASC, CCASC and ACASC adsorbent mass, respectively. This readily available adsorbent is efficient in the uptake of Cr(VI) ion in aqueous solution, thus, it could be an excellent alternative for the removal of heavy metals and organic matter from water and wastewater.","Kinetics and equilibrium studies of adsorption of chromium(VI) ion from industrial wastewater using Chrysophyllum albidum (Sapotaceae) seed shells Abs: A new biosorbent has been prepared by coating Chrysophyllum albidum (Sapotaceae) seed shells with chitosan and/or oxidizing agents such as sulfuric acid. This study investigated the technical feasibility of activated and modified activated C. albidum seed shells carbons for the adsorption of chromium(VI) from aqueous solution. The sorption process with respect to its equilibria and kinetics as well as the effects of pH, contact time, adsorbent mass, adsorbate concentration and particle size on adsorption was also studied. The most effective pH range was found to be between 4.5 and 5 for the sorption of the metal ion. The pseudo-first-order rate equation by Lagergren and pseudo-second-order rate equation were tested on the kinetic data, the adsorption process followed pseudo-second-order rate kinetics, also, isotherm data was analyzed for possible agreement with the Langmuir and Freundlich adsorption isotherms, the Freundlich and Langmuir models for dynamics of metal ion uptake proposed in this work fitted the experimental data reasonably well. However, equilibrium sorption data were better represented by Langmuir model than Freundlich. The adsorption capacity calculated from Langmuir isotherm was 84.31, 76.23 and 59.63mgCr(VI)/g at initial pH of 3.0 at 30 degrees C for the particle size of 1.00-1.25mm with the use of 12.5, 16.5 and 2.1g/L of CACASC, CCASC and ACASC adsorbent mass, respectively. This readily available adsorbent is efficient in the uptake of Cr(VI) ion in aqueous solution, thus, it could be an excellent alternative for the removal of heavy metals and organic matter from water and wastewater."
1231669,Polti et al. 2009,Bioremediation of chromium(VI) contaminated soil by Streptomyces sp. MC1,"This work provides quantitative information on Cr(VI) reduction in soil samples by an indigenous actinomycete. Streptomyces sp. MC1, previously isolated from sugarcane, has shown ability to reduce Cr(VI) in liquid minimal medium. A reduction of 100 and 75% was obtained at initial Cr(VI) concentrations of 5 and 50 mg l(-1), respectively, after 48 h of incubation. Bioremediation ability of Streptomyces sp. MC1 was assayed in soil extracts and soil samples. Relative growth of Streptomyces sp. MC1 was 77 and 38% when grown in soil extract with 10 and 50 mg l(-1) of Cr(VI), respectively. MC1 was able to reduce 30% of Cr(VI) after 96 h of incubation with 10 mg l(-1) of Cr(VI), and reduction coincided with the exponential growth phase at pH 7 and 30 degrees C.In soil samples, Streptomyces sp. MC1 was able to reduce up to 94% of the Cr(VI) bioavailability (50 mg kg(-1)) after 7 d. These results were compared with non-inoculated soil samples with Cr(VI). Bioremediation activity of Streptomyces sp. MC1 was not inhibited by natural soil microbial flora. Besides, Streptomyces sp. MC1 growth was not inhibited by 50 mg kg(-1) of Cr(VI). In contrast to findings obtained by other authors, our results showed almost complete Cr(VI) removal from soil without any previous treatment, and without addition of any substrate and with a normal soil humidity level. These results confirm the Cr(VI)-contaminated soil bioremediation potential of Streptomyces sp. MC1.","Bioremediation of chromium(VI) contaminated soil by Streptomyces sp. MC1 Abs: This work provides quantitative information on Cr(VI) reduction in soil samples by an indigenous actinomycete. Streptomyces sp. MC1, previously isolated from sugarcane, has shown ability to reduce Cr(VI) in liquid minimal medium. A reduction of 100 and 75% was obtained at initial Cr(VI) concentrations of 5 and 50 mg l(-1), respectively, after 48 h of incubation. Bioremediation ability of Streptomyces sp. MC1 was assayed in soil extracts and soil samples. Relative growth of Streptomyces sp. MC1 was 77 and 38% when grown in soil extract with 10 and 50 mg l(-1) of Cr(VI), respectively. MC1 was able to reduce 30% of Cr(VI) after 96 h of incubation with 10 mg l(-1) of Cr(VI), and reduction coincided with the exponential growth phase at pH 7 and 30 degrees C.In soil samples, Streptomyces sp. MC1 was able to reduce up to 94% of the Cr(VI) bioavailability (50 mg kg(-1)) after 7 d. These results were compared with non-inoculated soil samples with Cr(VI). Bioremediation activity of Streptomyces sp. MC1 was not inhibited by natural soil microbial flora. Besides, Streptomyces sp. MC1 growth was not inhibited by 50 mg kg(-1) of Cr(VI). In contrast to findings obtained by other authors, our results showed almost complete Cr(VI) removal from soil without any previous treatment, and without addition of any substrate and with a normal soil humidity level. These results confirm the Cr(VI)-contaminated soil bioremediation potential of Streptomyces sp. MC1."
1231668,Tamblyn et al. 2009,A role for Mus81 in the repair of chromium-induced DNA damage,"Hexavalent chromium (Cr[VI]) is a toxic environmental contaminant that is capable of producing a broad spectrum of DNA damage. The ability of Cr[VI] to induce mutagenesis and neoplastic transformation has been attributed to its genotoxic action, however our understanding of molecular mechanisms involved in the repair of Cr[VI]-induced DNA damage remains incomplete. Here, we report that Mus81, an enzyme that participates with Eme1 in the resolution of replication fork damage caused by certain lesions, is involved in the repair of Cr[VI]-induced DNA damage. Mus81-deficient cells were found to be more susceptible to Cr[VI]-induced proliferation arrest and more sensitive to the long-term cytotoxic effects of Cr[VI] than isogenic wild-type cells. Following Cr[VI] exposure, Mus81-deficient cells displayed a lag in the disappearance of Rad51 foci, exhibited elevated replication-associated gamma-H2AX and showed an increased incidence of chromosomal instability compared to wild-type cells. Our findings support a role for Mus81 in the resolution of replication-associated DNA damage associated with this genotoxic agent, by converting Cr[VI]-DNA lesions into a form more amenable for homologous recombination.","A role for Mus81 in the repair of chromium-induced DNA damage Abs: Hexavalent chromium (Cr[VI]) is a toxic environmental contaminant that is capable of producing a broad spectrum of DNA damage. The ability of Cr[VI] to induce mutagenesis and neoplastic transformation has been attributed to its genotoxic action, however our understanding of molecular mechanisms involved in the repair of Cr[VI]-induced DNA damage remains incomplete. Here, we report that Mus81, an enzyme that participates with Eme1 in the resolution of replication fork damage caused by certain lesions, is involved in the repair of Cr[VI]-induced DNA damage. Mus81-deficient cells were found to be more susceptible to Cr[VI]-induced proliferation arrest and more sensitive to the long-term cytotoxic effects of Cr[VI] than isogenic wild-type cells. Following Cr[VI] exposure, Mus81-deficient cells displayed a lag in the disappearance of Rad51 foci, exhibited elevated replication-associated gamma-H2AX and showed an increased incidence of chromosomal instability compared to wild-type cells. Our findings support a role for Mus81 in the resolution of replication-associated DNA damage associated with this genotoxic agent, by converting Cr[VI]-DNA lesions into a form more amenable for homologous recombination."
1231666,Afolaranmi et al. 2010,The effect of anticoagulants on the distribution of chromium VI in blood fractions,"Metal-on-metal resurfacing arthroplasty is associated with elevated circulating levels of cobalt and chromium ions. To establish the long-term safety of metal-on-metal resurfacing arthroplasty, it has been recommended that during clinical follow-up of these patients, the levels of these metal ions in blood be monitored. In this article, we provide information on the distribution of chromium VI ions (the predominant form of chromium released by cobalt-chrome alloys in vivo and in vitro) in blood fractions. Chromium VI is predominantly partitioned into red blood cells compared with plasma (analysis of variance, P < .05). The extent of accumulation in red blood cells is influenced by the anticoagulant used to collect the blood, with EDTA giving a lower partitioning into red cells compared with sodium citrate and sodium heparin.","The effect of anticoagulants on the distribution of chromium VI in blood fractions Abs: Metal-on-metal resurfacing arthroplasty is associated with elevated circulating levels of cobalt and chromium ions. To establish the long-term safety of metal-on-metal resurfacing arthroplasty, it has been recommended that during clinical follow-up of these patients, the levels of these metal ions in blood be monitored. In this article, we provide information on the distribution of chromium VI ions (the predominant form of chromium released by cobalt-chrome alloys in vivo and in vitro) in blood fractions. Chromium VI is predominantly partitioned into red blood cells compared with plasma (analysis of variance, P < .05). The extent of accumulation in red blood cells is influenced by the anticoagulant used to collect the blood, with EDTA giving a lower partitioning into red cells compared with sodium citrate and sodium heparin."
1231664,Abbas and  Ali 2007,"Study the effect of hexavalent chromium on some biochemical, citotoxicological and histopathological aspects of the Orechromis spp. fish","In nature chromium occurs in divalent, trivalent and hexavalent forms. Hexavalent chromium predominates over the trivalent form in natural waters. Knowledge of acute toxicity of a xenobiotic often can be very helpful in predicting and preventing acute damage to aquatic life in receiving waters as well as in regulating toxic waste discharges. The 96 h LC50 tests can be used to obtain toxicity data as rapidly and inexpensively as possible. In the present study, results showed a significant decrease in total glycogen, total lipids and total protein of liver, muscles and gills after 24 and 96 h of exposure to 96 h LC50 of hexavalent chromium (43.7 mg L(-1)). Cytotoxicity of metals is important because some metals are potential mutagens able to induce tumors in humans and experimental animals, the treatment of(Cr VI) at 43.7 mg L(-1) was for 24 and 96 h, respectively. DNA was extracted after treatment from brain and liver of the tested fish. Our results showed appearance of polymorphic bands at the long treatment interval (96 h) ofhexavalent chromium. However, these bands were not appeared when the fish were exposed to the (Cr VI) for the short treatment interval (24 h). Histopathological changes were seen in liver, muscle and gills sections of chromium-exposed fishes. The obtained results were discussed in the study research.","Study the effect of hexavalent chromium on some biochemical, citotoxicological and histopathological aspects of the Orechromis spp. fish Abs: In nature chromium occurs in divalent, trivalent and hexavalent forms. Hexavalent chromium predominates over the trivalent form in natural waters. Knowledge of acute toxicity of a xenobiotic often can be very helpful in predicting and preventing acute damage to aquatic life in receiving waters as well as in regulating toxic waste discharges. The 96 h LC50 tests can be used to obtain toxicity data as rapidly and inexpensively as possible. In the present study, results showed a significant decrease in total glycogen, total lipids and total protein of liver, muscles and gills after 24 and 96 h of exposure to 96 h LC50 of hexavalent chromium (43.7 mg L(-1)). Cytotoxicity of metals is important because some metals are potential mutagens able to induce tumors in humans and experimental animals, the treatment of(Cr VI) at 43.7 mg L(-1) was for 24 and 96 h, respectively. DNA was extracted after treatment from brain and liver of the tested fish. Our results showed appearance of polymorphic bands at the long treatment interval (96 h) ofhexavalent chromium. However, these bands were not appeared when the fish were exposed to the (Cr VI) for the short treatment interval (24 h). Histopathological changes were seen in liver, muscle and gills sections of chromium-exposed fishes. The obtained results were discussed in the study research."
1231663,Muneer et al. 2009,Evaluation of consortia of microorganisms for efficient removal of hexavalent chromium from industrial wastewater,"The Chromium (Cr) uptake ability of Cr-resistant bacterium Bacillus thuringiensis, yeast Candida etschellsii, and a protozoan Stylonychia mytilus, isolated from industrial waste water, was evaluated individually and in different combinations. It was found that the three types of microorganisms grown together in a culture medium could collectively uptake 90% of Cr(6+) from the culture medium as against 82% by bacterium + protozoan or yeast + protozoan combined culture, each. Consortium of bacterium, yeast and ciliates therefore could make much more efficient inoculum for remediation of Cr-contaminated industrial waste water.","Evaluation of consortia of microorganisms for efficient removal of hexavalent chromium from industrial wastewater Abs: The Chromium (Cr) uptake ability of Cr-resistant bacterium Bacillus thuringiensis, yeast Candida etschellsii, and a protozoan Stylonychia mytilus, isolated from industrial waste water, was evaluated individually and in different combinations. It was found that the three types of microorganisms grown together in a culture medium could collectively uptake 90% of Cr(6+) from the culture medium as against 82% by bacterium + protozoan or yeast + protozoan combined culture, each. Consortium of bacterium, yeast and ciliates therefore could make much more efficient inoculum for remediation of Cr-contaminated industrial waste water."
1231662,Kerger et al. 2009,Cancer mortality in chinese populations surrounding an alloy plant with chromium smelting operations,"This report is a further characterization of data from an ecological cancer mortality study of a population (about 10,000) exposed to groundwater contaminated by hexavalent chromium [Cr(VI)] up to 20 mg/L near JinZhou City in the LiaoNing Province of China between 1960 and 1978. Prior reports showed an elevation in all-cancer mortality from 1970 to 1978 averaged across five agricultural villages with Cr(VI) in groundwater relative to average cancer rates for the district and province. The current study compares the cancer rates during the same time period for the same five exposed villages to those of four nearby areas with no Cr(VI) in groundwater. The use of a local comparison group is considered superior to the use of district or province averages because of the expected improved similarity among unmeasured covariates in nearby areas. The average lung-, stomach-, and all-cancer mortality rates for the three agricultural villages without Cr(VI) in groundwater were not statistically different from those of the five agricultural villages with Cr(VI) in groundwater. Also, three surrogate measures of village drinking-water Cr(VI) dose did not significantly correlate with cancer mortality rates in the five exposed villages. Further, the industrial town in which the Cr(VI) source was located had different demographics and a different pattern of stomach and lung cancers compared to the adjacent agricultural villages, regardless of Cr(VI) groundwater exposure. The results of other local investigations on cancer mortality and genotoxicity in the exposed populations are reviewed. The overall findings in the studied population do not indicate a dose-response relationship or a coherent pattern of association of lung-, stomach-, or all-cancer mortality with exposure to Cr(VI)-contaminated groundwater.","Cancer mortality in chinese populations surrounding an alloy plant with chromium smelting operations Abs: This report is a further characterization of data from an ecological cancer mortality study of a population (about 10,000) exposed to groundwater contaminated by hexavalent chromium [Cr(VI)] up to 20 mg/L near JinZhou City in the LiaoNing Province of China between 1960 and 1978. Prior reports showed an elevation in all-cancer mortality from 1970 to 1978 averaged across five agricultural villages with Cr(VI) in groundwater relative to average cancer rates for the district and province. The current study compares the cancer rates during the same time period for the same five exposed villages to those of four nearby areas with no Cr(VI) in groundwater. The use of a local comparison group is considered superior to the use of district or province averages because of the expected improved similarity among unmeasured covariates in nearby areas. The average lung-, stomach-, and all-cancer mortality rates for the three agricultural villages without Cr(VI) in groundwater were not statistically different from those of the five agricultural villages with Cr(VI) in groundwater. Also, three surrogate measures of village drinking-water Cr(VI) dose did not significantly correlate with cancer mortality rates in the five exposed villages. Further, the industrial town in which the Cr(VI) source was located had different demographics and a different pattern of stomach and lung cancers compared to the adjacent agricultural villages, regardless of Cr(VI) groundwater exposure. The results of other local investigations on cancer mortality and genotoxicity in the exposed populations are reviewed. The overall findings in the studied population do not indicate a dose-response relationship or a coherent pattern of association of lung-, stomach-, or all-cancer mortality with exposure to Cr(VI)-contaminated groundwater."
1231661,Svecevicius 2009,Use of behavioral responses of rainbow trout Oncorhynchus mykiss in identifying sublethal exposure to hexavalent chromium,"Laboratory tests were conducted in a flow-through apparatus on 1-year-old rainbow trout Oncorhynchus mykiss to evaluate the sensitivity of a number of their behavioral responses to hexavalent chromium (Cr(6+)). Test fish were exposed to Cr(6+) concentrations corresponding to 0.001-1 parts of the rainbow trout 96-h LC50 (0.029-28.5 mg Cr/L, respectively) in short-term (15 min) tests. Sensitivity parameter responses could be arranged into the following sequence: latent period of detection response = locomotor activity &gt; gill ventilation frequency &gt; coughing rate. All the rainbow trout responses were sensitive behavioral indicators of sublethal exposure. Behavioral responses meet the criteria as rapid tools for bioassay testing and could be easily standardized using Cr(6+) as a reference toxicant.","Use of behavioral responses of rainbow trout Oncorhynchus mykiss in identifying sublethal exposure to hexavalent chromium Abs: Laboratory tests were conducted in a flow-through apparatus on 1-year-old rainbow trout Oncorhynchus mykiss to evaluate the sensitivity of a number of their behavioral responses to hexavalent chromium (Cr(6+)). Test fish were exposed to Cr(6+) concentrations corresponding to 0.001-1 parts of the rainbow trout 96-h LC50 (0.029-28.5 mg Cr/L, respectively) in short-term (15 min) tests. Sensitivity parameter responses could be arranged into the following sequence: latent period of detection response = locomotor activity &gt; gill ventilation frequency &gt; coughing rate. All the rainbow trout responses were sensitive behavioral indicators of sublethal exposure. Behavioral responses meet the criteria as rapid tools for bioassay testing and could be easily standardized using Cr(6+) as a reference toxicant."
1231660,Das and  Guha 2009,Biosorption of hexavalent chromium by Termitomyces clypeatus biomass: kinetics and transmission electron microscopic study,"Biosorption of Cr(+6) by Termitomyces clypeatus has been investigated involving kinetics, transmission electron microscopy (TEM) and Fourier transform infrared spectroscopic (FTIR) studies. Kinetics experiments reveal that the uptake of chromium by live cell involves initial rapid surface binding followed by relatively slow intracellular accumulation. Of the different chromate analogues tested, only sulfate ion reduces the uptake of chromium to the extent of approximately 30% indicating chromate ions accumulation into the cytoplasm using sulfate transport system. Metabolic inhibitors, e.g. N,N'-dicyclohexylcarbodiimide, 2,4-ditrophenol and sodium azide inhibit chromate accumulation by approximately 30% in live cell. This indicates that accumulation of chromium into the cytoplasm occurs through the active transport system. TEM-EDXA analysis reveals that the chromium localizes in the cell wall and also in the cytoplasm. Reduction of chromate ions takes place by chromate reductase activity of cell-free extracts of T. clypeatus. FTIR study indicates that chromate ions accumulate into the cytoplasm and then reduced to less toxic Cr(+3) compounds.","Biosorption of hexavalent chromium by Termitomyces clypeatus biomass: kinetics and transmission electron microscopic study Abs: Biosorption of Cr(+6) by Termitomyces clypeatus has been investigated involving kinetics, transmission electron microscopy (TEM) and Fourier transform infrared spectroscopic (FTIR) studies. Kinetics experiments reveal that the uptake of chromium by live cell involves initial rapid surface binding followed by relatively slow intracellular accumulation. Of the different chromate analogues tested, only sulfate ion reduces the uptake of chromium to the extent of approximately 30% indicating chromate ions accumulation into the cytoplasm using sulfate transport system. Metabolic inhibitors, e.g. N,N'-dicyclohexylcarbodiimide, 2,4-ditrophenol and sodium azide inhibit chromate accumulation by approximately 30% in live cell. This indicates that accumulation of chromium into the cytoplasm occurs through the active transport system. TEM-EDXA analysis reveals that the chromium localizes in the cell wall and also in the cytoplasm. Reduction of chromate ions takes place by chromate reductase activity of cell-free extracts of T. clypeatus. FTIR study indicates that chromate ions accumulate into the cytoplasm and then reduced to less toxic Cr(+3) compounds."
1231659,Ashley et al. 2009,Evaluation of sequential extraction procedures for soluble and insoluble hexavalent chromium compounds in workplace air samples,"Because toxicities may differ for Cr(VI) compounds of varying solubility, some countries and organizations have promulgated different occupational exposure limits (OELs) for soluble and insoluble hexavalent chromium (Cr(VI)) compounds, and analytical methods are needed to determine these species in workplace air samples. To address this need, international standard methods ASTM D6832 and ISO 16740 have been published that describe sequential extraction techniques for soluble and insoluble Cr(VI) in samples collected from occupational settings. However, no published performance data were previously available for these Cr(VI) sequential extraction procedures. In this work, the sequential extraction methods outlined in the relevant international standards were investigated. The procedures tested involved the use of either deionized water or an ammonium sulfate/ammonium hydroxide buffer solution to target soluble Cr(VI) species. This was followed by extraction in a sodium carbonate/sodium hydroxide buffer solution to dissolve insoluble Cr(VI) compounds. Three-step sequential extraction with (1) water, (2) sulfate buffer and (3) carbonate buffer was also investigated. Sequential extractions were carried out on spiked samples of soluble, sparingly soluble and insoluble Cr(VI) compounds, and analyses were then generally carried out by using the diphenylcarbazide method. Similar experiments were performed on paint pigment samples and on airborne particulate filter samples collected from stainless steel welding. Potential interferences from soluble and insoluble Cr(III) compounds, as well as from Fe(II), were investigated. Interferences from Cr(III) species were generally absent, while the presence of Fe(II) resulted in low Cr(VI) recoveries. Two-step sequential extraction of spiked samples with (first) either water or sulfate buffer, and then carbonate buffer, yielded quantitative recoveries of soluble Cr(VI) and insoluble Cr(VI), respectively. Three-step sequential extraction gave excessively high recoveries of soluble Cr(VI), low recoveries of sparingly soluble Cr(VI), and quantitative recoveries of insoluble Cr(VI). Experiments on paint pigment samples using two-step extraction with water and carbonate buffer yielded varying percentages of relative fractions of soluble and insoluble Cr(VI). Sequential extractions of stainless steel welding fume air filter samples demonstrated the predominance of soluble Cr(VI) compounds in such samples. The performance data obtained in this work support the Cr(VI) sequential extraction procedures described in the international standards.","Evaluation of sequential extraction procedures for soluble and insoluble hexavalent chromium compounds in workplace air samples Abs: Because toxicities may differ for Cr(VI) compounds of varying solubility, some countries and organizations have promulgated different occupational exposure limits (OELs) for soluble and insoluble hexavalent chromium (Cr(VI)) compounds, and analytical methods are needed to determine these species in workplace air samples. To address this need, international standard methods ASTM D6832 and ISO 16740 have been published that describe sequential extraction techniques for soluble and insoluble Cr(VI) in samples collected from occupational settings. However, no published performance data were previously available for these Cr(VI) sequential extraction procedures. In this work, the sequential extraction methods outlined in the relevant international standards were investigated. The procedures tested involved the use of either deionized water or an ammonium sulfate/ammonium hydroxide buffer solution to target soluble Cr(VI) species. This was followed by extraction in a sodium carbonate/sodium hydroxide buffer solution to dissolve insoluble Cr(VI) compounds. Three-step sequential extraction with (1) water, (2) sulfate buffer and (3) carbonate buffer was also investigated. Sequential extractions were carried out on spiked samples of soluble, sparingly soluble and insoluble Cr(VI) compounds, and analyses were then generally carried out by using the diphenylcarbazide method. Similar experiments were performed on paint pigment samples and on airborne particulate filter samples collected from stainless steel welding. Potential interferences from soluble and insoluble Cr(III) compounds, as well as from Fe(II), were investigated. Interferences from Cr(III) species were generally absent, while the presence of Fe(II) resulted in low Cr(VI) recoveries. Two-step sequential extraction of spiked samples with (first) either water or sulfate buffer, and then carbonate buffer, yielded quantitative recoveries of soluble Cr(VI) and insoluble Cr(VI), respectively. Three-step sequential extraction gave excessively high recoveries of soluble Cr(VI), low recoveries of sparingly soluble Cr(VI), and quantitative recoveries of insoluble Cr(VI). Experiments on paint pigment samples using two-step extraction with water and carbonate buffer yielded varying percentages of relative fractions of soluble and insoluble Cr(VI). Sequential extractions of stainless steel welding fume air filter samples demonstrated the predominance of soluble Cr(VI) compounds in such samples. The performance data obtained in this work support the Cr(VI) sequential extraction procedures described in the international standards."
1231658,Janos et al. 2009,Reduction and immobilization of hexavalent chromium with coal- and humate-based sorbents,"Two kinds of the commercially available sorbents containing humic acids as active constituents were used for Cr(VI) reduction and removal, namely oxihumolite (naturally occurring weathered young brown coal) and iron humate (IH) (waste material produced during industrial manufacturing of humic substances). The mechanisms of the chromium removal involve the reduction of Cr(VI) (by humic substances or by Fe(II) ions) and subsequent binding of Cr(III) to a humic acid matrix. Other metal-binding mechanisms possibly effective in the process of Cr(VI) removal, e.g., coprecipitation or surface precipitation of Fe(III)/Cr(III) hydroxides, are also discussed. Oxihumolite was able to remove Cr(VI) from strongly acidic solutions with pH below ca. 2. IH, on the other hand, exhibited a maximum sorption capability in slightly acidic solutions with pH above ca. 3. Over the whole examined range (pH 1-5), however, IH was able to reduce Cr(VI) almost completely to its less toxic trivalent state. A sufficiently high sorption capacity (20 mg g(-1)) was found for chromium removal with IH in an unbuffered system, where the &quot;natural&quot; pH values governed by the buffering capacity of the sorbent itself ranged from 3.9 to 4.6. It follows from extraction studies with the loaded (spent) sorbents that chromium is bound strongly to the sorbent, and thus risks of its subsequent liberation into the environment are minimized. Similarity in the extraction behavior of the Cr(III)-loaded and Cr(VI)-loaded sorbents supported the above-mentioned mechanisms of the Cr(VI) removal.","Reduction and immobilization of hexavalent chromium with coal- and humate-based sorbents Abs: Two kinds of the commercially available sorbents containing humic acids as active constituents were used for Cr(VI) reduction and removal, namely oxihumolite (naturally occurring weathered young brown coal) and iron humate (IH) (waste material produced during industrial manufacturing of humic substances). The mechanisms of the chromium removal involve the reduction of Cr(VI) (by humic substances or by Fe(II) ions) and subsequent binding of Cr(III) to a humic acid matrix. Other metal-binding mechanisms possibly effective in the process of Cr(VI) removal, e.g., coprecipitation or surface precipitation of Fe(III)/Cr(III) hydroxides, are also discussed. Oxihumolite was able to remove Cr(VI) from strongly acidic solutions with pH below ca. 2. IH, on the other hand, exhibited a maximum sorption capability in slightly acidic solutions with pH above ca. 3. Over the whole examined range (pH 1-5), however, IH was able to reduce Cr(VI) almost completely to its less toxic trivalent state. A sufficiently high sorption capacity (20 mg g(-1)) was found for chromium removal with IH in an unbuffered system, where the &quot;natural&quot; pH values governed by the buffering capacity of the sorbent itself ranged from 3.9 to 4.6. It follows from extraction studies with the loaded (spent) sorbents that chromium is bound strongly to the sorbent, and thus risks of its subsequent liberation into the environment are minimized. Similarity in the extraction behavior of the Cr(III)-loaded and Cr(VI)-loaded sorbents supported the above-mentioned mechanisms of the Cr(VI) removal."
1231655,Geng et al. 2009,Kinetics of hexavalent chromium removal from water by chitosan-Fe0 nanoparticles,"Chitosan-Fe(0) nanoparticles (chitosan-Fe(0)) were prepared using nontoxic and biodegradable chitosan as a stabilizer. Batch experiments were conducted to evaluate the influences of initial Cr(VI) concentration and other factors on Cr(VI) reduction on the surface of the chitosan-Fe(0). The overall disappearance of Cr(VI) may include both physical adsorption of Cr(VI) onto the chitosan-Fe(0) surface and subsequent reduction of Cr(VI) to Cr(III). The rate of reduction of Cr(VI) to Cr(III) can be expressed by a pseudo-first-order reaction kinetics. The rate constants increase with the increase in temperature and iron loading but decrease with the increase in initial Cr(VI) concentration and pH. The apparent activation energy is found to be 33 kJ mol(-1), which is characteristic of a chemically controlled reaction. Characterization with high-resolution X-ray photoelectron spectroscopy reveals that after the reaction, relative to Cr(VI) and Fe(0), Cr(III) and Fe(III) are the predominant species on the surface of chitosan-Fe(0). Chitosan has also been found to inhibit the formation of Fe(III)-Cr(III) precipitation due to its high efficiency in chelating the Fe(III) ions. This study demonstrates that chitosan-Fe(0) has the potential to become an effective agent for in situ subsurface environment remediation.","Kinetics of hexavalent chromium removal from water by chitosan-Fe0 nanoparticles Abs: Chitosan-Fe(0) nanoparticles (chitosan-Fe(0)) were prepared using nontoxic and biodegradable chitosan as a stabilizer. Batch experiments were conducted to evaluate the influences of initial Cr(VI) concentration and other factors on Cr(VI) reduction on the surface of the chitosan-Fe(0). The overall disappearance of Cr(VI) may include both physical adsorption of Cr(VI) onto the chitosan-Fe(0) surface and subsequent reduction of Cr(VI) to Cr(III). The rate of reduction of Cr(VI) to Cr(III) can be expressed by a pseudo-first-order reaction kinetics. The rate constants increase with the increase in temperature and iron loading but decrease with the increase in initial Cr(VI) concentration and pH. The apparent activation energy is found to be 33 kJ mol(-1), which is characteristic of a chemically controlled reaction. Characterization with high-resolution X-ray photoelectron spectroscopy reveals that after the reaction, relative to Cr(VI) and Fe(0), Cr(III) and Fe(III) are the predominant species on the surface of chitosan-Fe(0). Chitosan has also been found to inhibit the formation of Fe(III)-Cr(III) precipitation due to its high efficiency in chelating the Fe(III) ions. This study demonstrates that chitosan-Fe(0) has the potential to become an effective agent for in situ subsurface environment remediation."
1231653,Leita et al. 2009,Soil humic acids may favour the persistence of hexavalent chromium in soil,"The interaction between hexavalent chromium Cr(VI), as K(2)CrO(4), and standard humic acids (HAs) in bulk solution was studied using three complementary analytical methods: UV-Visible spectroscopy, X-ray absorption spectroscopy and differential pulse stripping voltammetry. The observed UV-Vis and X-ray absorption spectra showed that, under our experimental conditions, HAs did not induce reduction of Cr(VI) to its trivalent chemical form. The interaction between Cr(VI) and HAs has rather led to the formation of Cr(VI)-HAs micelles via supramolecular chemical processes. The reported results could contribute towards explaining the relative persistence of ecotoxic hexavalent chromium in soils.","Soil humic acids may favour the persistence of hexavalent chromium in soil Abs: The interaction between hexavalent chromium Cr(VI), as K(2)CrO(4), and standard humic acids (HAs) in bulk solution was studied using three complementary analytical methods: UV-Visible spectroscopy, X-ray absorption spectroscopy and differential pulse stripping voltammetry. The observed UV-Vis and X-ray absorption spectra showed that, under our experimental conditions, HAs did not induce reduction of Cr(VI) to its trivalent chemical form. The interaction between Cr(VI) and HAs has rather led to the formation of Cr(VI)-HAs micelles via supramolecular chemical processes. The reported results could contribute towards explaining the relative persistence of ecotoxic hexavalent chromium in soils."
1231652,Raghunathan et al. 2010,Changes in protein expression associated with chronic in vitro exposure of hexavalent chromium to osteoblasts and monocytes: A proteomic approach,"Cr (VI) is a well-recognized environmental toxin and carcinogen. It is known to be released from orthopedic metal implants in-situ by biocorrosion and is speculated to play a role in periprosthetic osteolysis. It is hence essential to understand its long-term biological effects. We have assessed the in vitro responses of osteoblasts and monocytes to chronic exposure (3 weeks) to Cr (VI), at concentrations that have been measured in patients with metal implants, using two-dimensional gel electrophoresis. Cr (VI) exposure resulted in a differential time-dependent regulation of glycolytic, stress, and cytoskeletal proteins. The proteins that have been found to be altered in expression play an essential role in normal cellular functioning such as energy metabolism, cell signaling, and proliferation. The results highlight the complex molecular changes that occur in both cell types with long-term exposure to Cr and may be useful in establishing a series of clinically useful biomarkers to monitor long-term use of metallic implants.","Changes in protein expression associated with chronic in vitro exposure of hexavalent chromium to osteoblasts and monocytes: A proteomic approach Abs: Cr (VI) is a well-recognized environmental toxin and carcinogen. It is known to be released from orthopedic metal implants in-situ by biocorrosion and is speculated to play a role in periprosthetic osteolysis. It is hence essential to understand its long-term biological effects. We have assessed the in vitro responses of osteoblasts and monocytes to chronic exposure (3 weeks) to Cr (VI), at concentrations that have been measured in patients with metal implants, using two-dimensional gel electrophoresis. Cr (VI) exposure resulted in a differential time-dependent regulation of glycolytic, stress, and cytoskeletal proteins. The proteins that have been found to be altered in expression play an essential role in normal cellular functioning such as energy metabolism, cell signaling, and proliferation. The results highlight the complex molecular changes that occur in both cell types with long-term exposure to Cr and may be useful in establishing a series of clinically useful biomarkers to monitor long-term use of metallic implants."
1231651,Chai et al. 2009,Cr (VI) remediation by indigenous bacteria in soils contaminated by chromium-containing slag,"Hexavalent chromium (Cr) is a toxic element causing serious environmental threat. Recently, more and more attention is paid to the bio-remediation of Cr (VI) in the contaminated soils. Cr (VI) remediation by indigenous bacteria in soils contaminated by chromium-containing slag at a steel-alloy factory in Hunan Province, China, was investigated in the present study. The results showed that when sufficient nutrients were amended into the contaminated soils, total Cr (VI) concentration declined from the initial value of 462.8 to 10 mg kg(-1) at 10 days and the removal rate was 97.8%. Water soluble Cr (VI) decreased from the initial concentration of 383.8 to 1.7 mg kg(-1). Exchangeable Cr (VI) and carbonates-bound Cr (VI) were removed by 92.6% and 82.4%, respectively. Meanwhile, four Cr (VI) resistant bacterial strains were isolated from the soil under the chromium-containing slag. Only one strain showed a high ability for Cr (VI) reduction in liquid culture. This strain was identified as Pannonibacter phragmitetus sp. by gene sequencing of 16S rRNA. X-ray photoelectron spectroscope (XPS) analysis indicated that Cr (VI) was reduced into trivalent chromium. The results suggest that indigenous bacterial strains have potential application for Cr (VI) remediation in the soils contaminated by chromium-containing slag.","Cr (VI) remediation by indigenous bacteria in soils contaminated by chromium-containing slag Abs: Hexavalent chromium (Cr) is a toxic element causing serious environmental threat. Recently, more and more attention is paid to the bio-remediation of Cr (VI) in the contaminated soils. Cr (VI) remediation by indigenous bacteria in soils contaminated by chromium-containing slag at a steel-alloy factory in Hunan Province, China, was investigated in the present study. The results showed that when sufficient nutrients were amended into the contaminated soils, total Cr (VI) concentration declined from the initial value of 462.8 to 10 mg kg(-1) at 10 days and the removal rate was 97.8%. Water soluble Cr (VI) decreased from the initial concentration of 383.8 to 1.7 mg kg(-1). Exchangeable Cr (VI) and carbonates-bound Cr (VI) were removed by 92.6% and 82.4%, respectively. Meanwhile, four Cr (VI) resistant bacterial strains were isolated from the soil under the chromium-containing slag. Only one strain showed a high ability for Cr (VI) reduction in liquid culture. This strain was identified as Pannonibacter phragmitetus sp. by gene sequencing of 16S rRNA. X-ray photoelectron spectroscope (XPS) analysis indicated that Cr (VI) was reduced into trivalent chromium. The results suggest that indigenous bacterial strains have potential application for Cr (VI) remediation in the soils contaminated by chromium-containing slag."
1231650,Ali Kumbasar 2009,Extraction of chromium (VI) from multicomponent acidic solutions by emulsion liquid membranes using TOPO as extractant,"Experimental results for the extraction of chromium (VI) from multicomponent acidic solutions by emulsion liquid membrane (ELM) using trioctylphosphine oxide (TOPO) as extractant are presented. The membrane phase consists of kerosene as diluent, TOPO as extractant, ECA 4360J (a nonionic polyamine) as surfactant and (NH(4))(2)CO(3) solution as stripping phase. Effects of various parameters such as mixing speed, type and concentration of stripping solution, surfactant and extractant concentrations, and volume ratio of the membrane phase to internal stripping phase on Cr (VI) extraction were studied and optimum conditions were determined. Results show that with proper adjustment of experimental conditions for the extraction of Cr (VI) can be enhanced to a great extent. This study also examined the effects of concentrations of acid and metal ions in the feed phase for the extraction of Cr (VI) ions. The results also showed that by appropriate selection of the extraction and stability conditions, nearly all of the Cr (VI) ions (100-500 mg/L) present in the acidic feed solution containing 1000 mg/L from each of Cu (II), Zn (II), Co (II), Ni (II) and Cd (II) ions were extracted within a few minutes. Concentration variations of Cr (VI) and other ions in the acidic solutions were determined by atomic absorption spectrophotometry.","Extraction of chromium (VI) from multicomponent acidic solutions by emulsion liquid membranes using TOPO as extractant Abs: Experimental results for the extraction of chromium (VI) from multicomponent acidic solutions by emulsion liquid membrane (ELM) using trioctylphosphine oxide (TOPO) as extractant are presented. The membrane phase consists of kerosene as diluent, TOPO as extractant, ECA 4360J (a nonionic polyamine) as surfactant and (NH(4))(2)CO(3) solution as stripping phase. Effects of various parameters such as mixing speed, type and concentration of stripping solution, surfactant and extractant concentrations, and volume ratio of the membrane phase to internal stripping phase on Cr (VI) extraction were studied and optimum conditions were determined. Results show that with proper adjustment of experimental conditions for the extraction of Cr (VI) can be enhanced to a great extent. This study also examined the effects of concentrations of acid and metal ions in the feed phase for the extraction of Cr (VI) ions. The results also showed that by appropriate selection of the extraction and stability conditions, nearly all of the Cr (VI) ions (100-500 mg/L) present in the acidic feed solution containing 1000 mg/L from each of Cu (II), Zn (II), Co (II), Ni (II) and Cd (II) ions were extracted within a few minutes. Concentration variations of Cr (VI) and other ions in the acidic solutions were determined by atomic absorption spectrophotometry."
1231648,Espinoza-Quiñones et al. 2009,Inhibition effect on the Allium cepa L. root growth when using hexavalent chromium-doped river waters,"The effect of Cr(6+) on Allium cepa root length was studied using both clean and polluted river waters. Seven series of Cr(6+)-doped polluted and non-polluted river waters were used to grow onions. Chromium concentration (Cr(6+)) of 4.2 mg L(-1)(EC(50) value), doped in clean river water caused a 50% reduction of root length, while in organically polluted samples similar root growth inhibition occurred at 12.0 mg Cr(6+) L(-1). The results suggested that there was a dislocation to higher values in toxic chromium concentration in polluted river water due to the eutrophization level of river water.","Inhibition effect on the Allium cepa L. root growth when using hexavalent chromium-doped river waters Abs: The effect of Cr(6+) on Allium cepa root length was studied using both clean and polluted river waters. Seven series of Cr(6+)-doped polluted and non-polluted river waters were used to grow onions. Chromium concentration (Cr(6+)) of 4.2 mg L(-1)(EC(50) value), doped in clean river water caused a 50% reduction of root length, while in organically polluted samples similar root growth inhibition occurred at 12.0 mg Cr(6+) L(-1). The results suggested that there was a dislocation to higher values in toxic chromium concentration in polluted river water due to the eutrophization level of river water."
1231647,Hwang et al. 2009,Safety assessment of chromium by exposure from cosmetic products,"Low level impurities often reside in cosmetic products. The aim of the present study was to estimate the human exposure to chromium from cosmetic products purchased at a local market in South Korea, and to assess the risk on public health. Hexavalent chromium is an impurity substance that contaminates cosmetic products during manufacture. The potential for chromium to induce and elicit allergic contact dermatitis, as well as the degree of chromium exposure from cosmetic products, were assessed. Chromium exposure was estimated using the chromium concentrations found in cosmetic samples taken from the local market along with the expected user pattern data that was taken from the literature. Of the cosmetics we tested and available for purchase on the Korean market, seven had chromium contents above the detection limit of 0.1 ppm (0.1 microg/mL), ranging from 0.2 to 3.15 ppm. In risk assessment, scientifically defensible dose-response relationships must be established for the end points of concern. In the case of chromium contaminated cosmetic products, this includes conducting dose-response assessments for allergic contact dermatitis following dermal exposure. This dose-response information can then be integrated with site-specific exposure assessments to regulate consumer safety by use of these products. We found that dermal exposure to chromium concentrations ranging from 0.0002 to 0.003 microg/cm(2) does not appear to cause concern for eliciting allergic contact dermatitis.","Safety assessment of chromium by exposure from cosmetic products Abs: Low level impurities often reside in cosmetic products. The aim of the present study was to estimate the human exposure to chromium from cosmetic products purchased at a local market in South Korea, and to assess the risk on public health. Hexavalent chromium is an impurity substance that contaminates cosmetic products during manufacture. The potential for chromium to induce and elicit allergic contact dermatitis, as well as the degree of chromium exposure from cosmetic products, were assessed. Chromium exposure was estimated using the chromium concentrations found in cosmetic samples taken from the local market along with the expected user pattern data that was taken from the literature. Of the cosmetics we tested and available for purchase on the Korean market, seven had chromium contents above the detection limit of 0.1 ppm (0.1 microg/mL), ranging from 0.2 to 3.15 ppm. In risk assessment, scientifically defensible dose-response relationships must be established for the end points of concern. In the case of chromium contaminated cosmetic products, this includes conducting dose-response assessments for allergic contact dermatitis following dermal exposure. This dose-response information can then be integrated with site-specific exposure assessments to regulate consumer safety by use of these products. We found that dermal exposure to chromium concentrations ranging from 0.0002 to 0.003 microg/cm(2) does not appear to cause concern for eliciting allergic contact dermatitis."
1231645,Ly and  Kim 2009,Diagnostic assay of chromium (VI) in the ex vivo fluid of the urine of a smoker using a fluorine-doped handmade sensor,"A voltammetric diagnosis of a chromium (VI) ion was investigated using a fluorine-doped graphite pencil electrode. Square wave (SW) stripping working conditions were attained at a high range of 0.051-0.45 mg L(-1) and a microrange of 0.05-0.4 microg L(-1) in a 0.1 M NH(4)H(2)PO(4) electrolyte solution, at a relative standard deviation of 1.68% (RSD, n=15), using 10.0 microg L(-1) Cr(VI). A fast experimental time was used only for the 120 sec SW accumulation time. An analytical detection-limit (DL) of 0.008 microg L(-1) was attained. DL appeared to be more sensitive than common voltammetric and spectrophotometric assays. The developed sensor was applied to tap water and the urine of a smoker. It was found that the methods can be applicable for in vivo fluid or medicinal diagnosis.","Diagnostic assay of chromium (VI) in the ex vivo fluid of the urine of a smoker using a fluorine-doped handmade sensor Abs: A voltammetric diagnosis of a chromium (VI) ion was investigated using a fluorine-doped graphite pencil electrode. Square wave (SW) stripping working conditions were attained at a high range of 0.051-0.45 mg L(-1) and a microrange of 0.05-0.4 microg L(-1) in a 0.1 M NH(4)H(2)PO(4) electrolyte solution, at a relative standard deviation of 1.68% (RSD, n=15), using 10.0 microg L(-1) Cr(VI). A fast experimental time was used only for the 120 sec SW accumulation time. An analytical detection-limit (DL) of 0.008 microg L(-1) was attained. DL appeared to be more sensitive than common voltammetric and spectrophotometric assays. The developed sensor was applied to tap water and the urine of a smoker. It was found that the methods can be applicable for in vivo fluid or medicinal diagnosis."
1231644,Chhikara and  Dhankhar 2008,Biosorption of Cr (VI) ions from electroplating industrial effluent using immobilized Aspergillus niger biomass,"A fungus, Aspergillus niger was chemically treated with 0.1 M H2SO4 and 0.1 N NaOH to form biosorbent and it was immobilized in calcium alginate beads. The biosorption capacity of immobilized biosorbents for Cr (VI) was found to depend on pH, contact time, biosorbent dose and initial concentration of Cr (VI). The maximum uptake of Cr (VI) was 92.5, 95.9 and 98.4 mg respectively at a pH of 1.5 and with an increase in pH up to 10.5 the metal uptake decreased gradually up to 38.75, 50.19 and 65.28 mg respectively for acid treated, untreated and base treated fungal biosorbents. Increase in biosorbent dose up to 1 g of biomass and contact time up to 60 min resulted in an increase in biosorption from 19.6, 15.6 and 26.1 mg at a biosorbent dose of 0.1 g 100 ml(-1) to 92.45, 95.7 and 98.52 mg at a biosorbent dose of 1.0 g 100 ml(-1) and then further increase in adsorbent dose and contact time did not resulted in more Cr (VI) adsorption by per unit weight of biosorbent. The value of Kad (adsorption rate constant) revealed the pseudo-first order nature of biosorption. The percentage metal uptake by the biosorbent was found to decrease upto 62.33, 52.67 and 83.5 percent respectively for acid treated, untreated and base treated fungal biosorbents at the 300 mgl(-1) Cr (VI) ion concentration. The resulted data was found to fit well in Langmuir model of adsorption isotherm with a high value of correlation coefficient. The value of Qmax, b (Langmuir constants), R(L) (separation factor) and delta G (Gibb's free energy) revealed the favourable nature of adsorption. The biosorbed metal was eluted from the biosorbent by using 0.1 M H2SO4 as elutant. Immobilized biosorbent can be reused for five consecutive biosorption/desorption cycles without apparent loss of efficiency after its reconditioning. The biosorbent was found to perform well in the electroplating industrial effluent.","Biosorption of Cr (VI) ions from electroplating industrial effluent using immobilized Aspergillus niger biomass Abs: A fungus, Aspergillus niger was chemically treated with 0.1 M H2SO4 and 0.1 N NaOH to form biosorbent and it was immobilized in calcium alginate beads. The biosorption capacity of immobilized biosorbents for Cr (VI) was found to depend on pH, contact time, biosorbent dose and initial concentration of Cr (VI). The maximum uptake of Cr (VI) was 92.5, 95.9 and 98.4 mg respectively at a pH of 1.5 and with an increase in pH up to 10.5 the metal uptake decreased gradually up to 38.75, 50.19 and 65.28 mg respectively for acid treated, untreated and base treated fungal biosorbents. Increase in biosorbent dose up to 1 g of biomass and contact time up to 60 min resulted in an increase in biosorption from 19.6, 15.6 and 26.1 mg at a biosorbent dose of 0.1 g 100 ml(-1) to 92.45, 95.7 and 98.52 mg at a biosorbent dose of 1.0 g 100 ml(-1) and then further increase in adsorbent dose and contact time did not resulted in more Cr (VI) adsorption by per unit weight of biosorbent. The value of Kad (adsorption rate constant) revealed the pseudo-first order nature of biosorption. The percentage metal uptake by the biosorbent was found to decrease upto 62.33, 52.67 and 83.5 percent respectively for acid treated, untreated and base treated fungal biosorbents at the 300 mgl(-1) Cr (VI) ion concentration. The resulted data was found to fit well in Langmuir model of adsorption isotherm with a high value of correlation coefficient. The value of Qmax, b (Langmuir constants), R(L) (separation factor) and delta G (Gibb's free energy) revealed the favourable nature of adsorption. The biosorbed metal was eluted from the biosorbent by using 0.1 M H2SO4 as elutant. Immobilized biosorbent can be reused for five consecutive biosorption/desorption cycles without apparent loss of efficiency after its reconditioning. The biosorbent was found to perform well in the electroplating industrial effluent."
1231642,Qafoku et al. 2009,Pathways of aqueous Cr(VI) attenuation in a slightly alkaline oxic subsurface,"Column experiments combined with geochemical modeling, microscopic inspections, spectroscopic interrogations, and wet chemical extractions were used to study sediment-dependent Cr(VI) desorption, physical location, mineral association, and attenuation mechanism(s) in four freshly or naturally aged contaminated sediments exposed to concentrated Cr(VI) waste fluids. Results showed that majority of Cr(VI) mass was easily removed from the sediments (equilibrium site K(d) varied from 0 to 0.33 mL g(-1) and equilibrium site fraction was greater than 95%). Long tailings of time-dependent Cr(VI) concentrations above maximum contaminant level of 1.9 micromol L(-1) were also observed (kinetically controlled fraction K(d) and desorption reaction half-lives varied from 0 to 45 mL g(-1), and from 76.1 to 126 h, respectively). Microscopic and spectroscopic measurements confirmed that Cr was concentrated within fine-grained coatings in small areas mainly rich in phyllosilicates that contained both Cr(III) and Cr(VI). However, Cr(VI) reduction was neither significant nor complete. Under slightly alkaline and oxic conditions, contaminant Cr in the sediments occurred: (i) In the highly mobile pool (over 95% of total Cr); (ii) In the slow and time-dependent releasing pool, which served as long-term source of contamination; (iii) As reduced Cr(III) which most likely formed during Cr(VI) reaction with aqueous, sorbed, or structural Fe(II).","Pathways of aqueous Cr(VI) attenuation in a slightly alkaline oxic subsurface Abs: Column experiments combined with geochemical modeling, microscopic inspections, spectroscopic interrogations, and wet chemical extractions were used to study sediment-dependent Cr(VI) desorption, physical location, mineral association, and attenuation mechanism(s) in four freshly or naturally aged contaminated sediments exposed to concentrated Cr(VI) waste fluids. Results showed that majority of Cr(VI) mass was easily removed from the sediments (equilibrium site K(d) varied from 0 to 0.33 mL g(-1) and equilibrium site fraction was greater than 95%). Long tailings of time-dependent Cr(VI) concentrations above maximum contaminant level of 1.9 micromol L(-1) were also observed (kinetically controlled fraction K(d) and desorption reaction half-lives varied from 0 to 45 mL g(-1), and from 76.1 to 126 h, respectively). Microscopic and spectroscopic measurements confirmed that Cr was concentrated within fine-grained coatings in small areas mainly rich in phyllosilicates that contained both Cr(III) and Cr(VI). However, Cr(VI) reduction was neither significant nor complete. Under slightly alkaline and oxic conditions, contaminant Cr in the sediments occurred: (i) In the highly mobile pool (over 95% of total Cr); (ii) In the slow and time-dependent releasing pool, which served as long-term source of contamination; (iii) As reduced Cr(III) which most likely formed during Cr(VI) reaction with aqueous, sorbed, or structural Fe(II)."
1231641,Chai et al. 2009,Hexavalent chromium reduction by Pannonibacter phragmitetus BB isolated from soil under chromium-containing slag heap,"The objective of this study was to find an indigenous Cr(VI)-reducing bacterium that can effectively be used for Cr(VI) remediation in the contaminated soils. The results showed that one isolate from soil under a chromium-containing slag heap at a steel-alloy factory in China had a strong ability of reducing Cr(VI). It can completely reduce 500 mg L(-1) Cr (VI) within 24 h. Based on 16S rRNA gene sequence and similarity analysis, this isolate was identified as Pannonibacter phragmitetus and assigned as strain BB. Images of scanning electron microscopy (SEM) indicated that the cell surface of P. phragmitetus BB remained intact without cell rupture under 500 mg L(-1) Cr (VI) stress. The transmission electron microscopy (TEM) patterns showed that the Cr(VI) reduction products were both bound to the outer surface of the cells and dispersed in the culture medium, thereby suggesting that the reduction of Cr (VI) occurred extracellularly. Elemental analysis by energy dispersive X-ray (EDX) revealed that Cr was the major element comprising the reduction product. Furthermore, X-ray photoelectron spectroscope (XPS) verified that the Cr(VI) reduction product was Cr(III) compounds.","Hexavalent chromium reduction by Pannonibacter phragmitetus BB isolated from soil under chromium-containing slag heap Abs: The objective of this study was to find an indigenous Cr(VI)-reducing bacterium that can effectively be used for Cr(VI) remediation in the contaminated soils. The results showed that one isolate from soil under a chromium-containing slag heap at a steel-alloy factory in China had a strong ability of reducing Cr(VI). It can completely reduce 500 mg L(-1) Cr (VI) within 24 h. Based on 16S rRNA gene sequence and similarity analysis, this isolate was identified as Pannonibacter phragmitetus and assigned as strain BB. Images of scanning electron microscopy (SEM) indicated that the cell surface of P. phragmitetus BB remained intact without cell rupture under 500 mg L(-1) Cr (VI) stress. The transmission electron microscopy (TEM) patterns showed that the Cr(VI) reduction products were both bound to the outer surface of the cells and dispersed in the culture medium, thereby suggesting that the reduction of Cr (VI) occurred extracellularly. Elemental analysis by energy dispersive X-ray (EDX) revealed that Cr was the major element comprising the reduction product. Furthermore, X-ray photoelectron spectroscope (XPS) verified that the Cr(VI) reduction product was Cr(III) compounds."
1231639,Lal et al. 2009,AKT1 mediates bypass of the G1/S checkpoint after genotoxic stress in normal human cells,"Certain forms of hexavalent chromium [Cr(VI)] are human carcinogens. Our recent work has shown that a broad range protein tyrosine phosphatase (PTP) inhibitor, sodium orthovanadate (SOV), abrogated both Cr(VI)-induced growth arrest and clonogenic lethality. Notably, SOV enhanced Cr(VI) mutation frequency, ostensibly through forced survival of genetically damaged cells. In the present study, co-treatment with this PTP inhibitor bypassed the Cr(VI)-induced G(1)/S checkpoint arrest in diploid human lung fibroblasts (HLF). Moreover, the PTP inhibitor abrogated the Cr(VI)-induced decrease in the expression of key effectors of the G(1)/S checkpoint [Cyclin D1, phospho Ser 807/811 Rb (pRB), p27]. Cr(VI)-induced G(1) arrest was associated with the cytoplasmic appearance of pRb and the nuclear localization of p27, both of which were reversed by the PTP inhibitor. The PTP inhibitor's reversal of G(1)/S checkpoint effector localization after Cr exposure was found to be Akt1-dependent, as this was abrogated by transfection with either akt1 siRNA or an Akt1-kinase dead plasmid. Furthermore, Akt1 activation alone was sufficient to induce G(1)/S checkpoint bypass and to prevent Cr(VI)-induced changes in pRb and p27 localization. In conclusion, this work establishes Akt1 activation to be both sufficient to bypass the Cr(VI)-induced G(1)/S checkpoint, as well as necessary for the observed PTP inhibitor effects on key mediators of the G(1)/S transition. The potential for Akt to bypass G(1)/S checkpoint arrest in the face of genotoxic damage could increase genomic instability, which is a hallmark of neoplastic progression.","AKT1 mediates bypass of the G1/S checkpoint after genotoxic stress in normal human cells Abs: Certain forms of hexavalent chromium [Cr(VI)] are human carcinogens. Our recent work has shown that a broad range protein tyrosine phosphatase (PTP) inhibitor, sodium orthovanadate (SOV), abrogated both Cr(VI)-induced growth arrest and clonogenic lethality. Notably, SOV enhanced Cr(VI) mutation frequency, ostensibly through forced survival of genetically damaged cells. In the present study, co-treatment with this PTP inhibitor bypassed the Cr(VI)-induced G(1)/S checkpoint arrest in diploid human lung fibroblasts (HLF). Moreover, the PTP inhibitor abrogated the Cr(VI)-induced decrease in the expression of key effectors of the G(1)/S checkpoint [Cyclin D1, phospho Ser 807/811 Rb (pRB), p27]. Cr(VI)-induced G(1) arrest was associated with the cytoplasmic appearance of pRb and the nuclear localization of p27, both of which were reversed by the PTP inhibitor. The PTP inhibitor's reversal of G(1)/S checkpoint effector localization after Cr exposure was found to be Akt1-dependent, as this was abrogated by transfection with either akt1 siRNA or an Akt1-kinase dead plasmid. Furthermore, Akt1 activation alone was sufficient to induce G(1)/S checkpoint bypass and to prevent Cr(VI)-induced changes in pRb and p27 localization. In conclusion, this work establishes Akt1 activation to be both sufficient to bypass the Cr(VI)-induced G(1)/S checkpoint, as well as necessary for the observed PTP inhibitor effects on key mediators of the G(1)/S transition. The potential for Akt to bypass G(1)/S checkpoint arrest in the face of genotoxic damage could increase genomic instability, which is a hallmark of neoplastic progression."
1231638,Sinha et al. 2009,Multivariate modeling of chromium-induced oxidative stress and biochemical changes in plants of Pistia stratiotes L,"Biochemical changes in the plants of Pistia stratiotes L., a free floating macrophyte exposed to different concentrations of hexavalent chromium (0, 10, 40, 60, 80 and 160 microM) for 48, 96 and 144 h were studied. Chromium-induced oxidative stress in macrophyte was investigated using the multivariate modeling approaches. Cluster analysis rendered two fairly distinct clusters (roots and shoots) of similar characteristics in terms of their biochemical responses. Discriminant analysis identified ascorbate peroxidase (APX) as discriminating variable between the root and shoot tissues. Principal components analysis results suggested that malondialdehyde (MDA), superoxide dismutase (SOD), APX, non-protein thiols (NP-SH), cysteine, ascorbic acid, and Cr-accumulation are dominant in root tissues, whereas, protein and guaiacol peroxidase (GPX) in shoots of the plant. Discriminant partial least squares analysis results further confirmed that MDA, SOD, NP-SH, cysteine, GPX, APX, ascorbic acid and Cr-accumulation dominated in the root tissues, while protein in the shoot. Three-way analysis helped in visualizing simultaneous influence of metal concentration and exposure duration on biochemical variables in plant tissues. The multivariate approaches, thus, allowed for the interpretation of the induced biochemical changes in the plant tissues exposed to chromium, which otherwise using the conventional approaches is difficult.","Multivariate modeling of chromium-induced oxidative stress and biochemical changes in plants of Pistia stratiotes L Abs: Biochemical changes in the plants of Pistia stratiotes L., a free floating macrophyte exposed to different concentrations of hexavalent chromium (0, 10, 40, 60, 80 and 160 microM) for 48, 96 and 144 h were studied. Chromium-induced oxidative stress in macrophyte was investigated using the multivariate modeling approaches. Cluster analysis rendered two fairly distinct clusters (roots and shoots) of similar characteristics in terms of their biochemical responses. Discriminant analysis identified ascorbate peroxidase (APX) as discriminating variable between the root and shoot tissues. Principal components analysis results suggested that malondialdehyde (MDA), superoxide dismutase (SOD), APX, non-protein thiols (NP-SH), cysteine, ascorbic acid, and Cr-accumulation are dominant in root tissues, whereas, protein and guaiacol peroxidase (GPX) in shoots of the plant. Discriminant partial least squares analysis results further confirmed that MDA, SOD, NP-SH, cysteine, GPX, APX, ascorbic acid and Cr-accumulation dominated in the root tissues, while protein in the shoot. Three-way analysis helped in visualizing simultaneous influence of metal concentration and exposure duration on biochemical variables in plant tissues. The multivariate approaches, thus, allowed for the interpretation of the induced biochemical changes in the plant tissues exposed to chromium, which otherwise using the conventional approaches is difficult."
1231637,Lakshmanraj et al. 2009,Studies on the biosorption of hexavalent chromium from aqueous solutions by using boiled mucilaginous seeds of Ocimum americanum,"Investigations were carried out to study the chromium removal efficiency of boiled mucilaginous seeds of Ocimum americanum. Batch experiments were conducted to study the biosorption kinetics of chromium removal for the concentrations 10mg/L, 20mg/L and 40 mg/L of chromium(VI) solutions. The biosorbent dosage was 8 g dry seeds/L. The toxic hexavalent chromium was reduced to less toxic chromium(III) in the presence of seeds and the reduced chromium was adsorbed on the mucilage of seeds. Both the chromium(VI) and chromium(III) were present in the aqueous phase. The optimum chromium reduction and adsorption was observed at the pH value 1.5. The biosorption data fitted well with Langmuir isotherm. The biosorption capacity calculated from the Langmuir isotherm was q=32 mg chromium(III)/g of dry seeds. The continuous column study was also carried out at the flow rate of 27 mL/h for the initial concentration 25mg/L of chromium(VI) feed solution using a packed bed column filled with boiled mucilaginous seeds. The maximum reduction of chromium(VI) to chromium(III) in the packed bed was 80%. The percentage removal of reduced chromium from the aqueous solution was 56.25%. This value was maintained constant until 0.52 L of chromium(VI) solution was pumped through the packed bed column. Thus the naturally immobilized polysaccharides on the seeds mimic the microbial polysaccharides in terms of their ability to adsorb heavy metals with an added advantage of making the immobilization step unnecessary which is a major cost factor of the metal removal process when microbial exopolysaccharides used. The uniform size and spherical shape of swollen seeds give an additional advantage to use them in a packed bed column for continuous removal of chromium(VI) from aqueous solutions.","Studies on the biosorption of hexavalent chromium from aqueous solutions by using boiled mucilaginous seeds of Ocimum americanum Abs: Investigations were carried out to study the chromium removal efficiency of boiled mucilaginous seeds of Ocimum americanum. Batch experiments were conducted to study the biosorption kinetics of chromium removal for the concentrations 10mg/L, 20mg/L and 40 mg/L of chromium(VI) solutions. The biosorbent dosage was 8 g dry seeds/L. The toxic hexavalent chromium was reduced to less toxic chromium(III) in the presence of seeds and the reduced chromium was adsorbed on the mucilage of seeds. Both the chromium(VI) and chromium(III) were present in the aqueous phase. The optimum chromium reduction and adsorption was observed at the pH value 1.5. The biosorption data fitted well with Langmuir isotherm. The biosorption capacity calculated from the Langmuir isotherm was q=32 mg chromium(III)/g of dry seeds. The continuous column study was also carried out at the flow rate of 27 mL/h for the initial concentration 25mg/L of chromium(VI) feed solution using a packed bed column filled with boiled mucilaginous seeds. The maximum reduction of chromium(VI) to chromium(III) in the packed bed was 80%. The percentage removal of reduced chromium from the aqueous solution was 56.25%. This value was maintained constant until 0.52 L of chromium(VI) solution was pumped through the packed bed column. Thus the naturally immobilized polysaccharides on the seeds mimic the microbial polysaccharides in terms of their ability to adsorb heavy metals with an added advantage of making the immobilization step unnecessary which is a major cost factor of the metal removal process when microbial exopolysaccharides used. The uniform size and spherical shape of swollen seeds give an additional advantage to use them in a packed bed column for continuous removal of chromium(VI) from aqueous solutions."
1231636,Wu et al. 2009,Synthesis of zero-valent copper-chitosan nanocomposites and their application for treatment of hexavalent chromium,"This study used ionotropic crosslinking to synthesize chitosan-tripolyphosphate chelating resin beads, which are used to fabricate zero-valent copper-chitosan nanocomposites. The copper nanoparticles were dispersed on chitosan-tripolyphosphate beads, and were thus able to maintain appropriate dispersion and stability, which greatly improves their applicability. The fabrication process contains two steps: using chitosan-tripolyphosphate beads to adsorb Cu(II) ions, followed by chemical reduction to reduce Cu(II) ions to zero-valent copper. This study explored the adsorption of synthesized chitosan-tripolyphosphate beads to Cu(II) ions, and used SEM/EDS, XPS, and TEM to examine the properties of zero-valent copper-chitosan nanocomposites. The results showed that, the adsorption behavior of hexavalent chromium from aqueous solution onto fabricated nanocomposites has better adsorption capacity than that of the chitosan-tripolyphosphate beads.","Synthesis of zero-valent copper-chitosan nanocomposites and their application for treatment of hexavalent chromium Abs: This study used ionotropic crosslinking to synthesize chitosan-tripolyphosphate chelating resin beads, which are used to fabricate zero-valent copper-chitosan nanocomposites. The copper nanoparticles were dispersed on chitosan-tripolyphosphate beads, and were thus able to maintain appropriate dispersion and stability, which greatly improves their applicability. The fabrication process contains two steps: using chitosan-tripolyphosphate beads to adsorb Cu(II) ions, followed by chemical reduction to reduce Cu(II) ions to zero-valent copper. This study explored the adsorption of synthesized chitosan-tripolyphosphate beads to Cu(II) ions, and used SEM/EDS, XPS, and TEM to examine the properties of zero-valent copper-chitosan nanocomposites. The results showed that, the adsorption behavior of hexavalent chromium from aqueous solution onto fabricated nanocomposites has better adsorption capacity than that of the chitosan-tripolyphosphate beads."
1231634,Mishra and  Mohanty 2009,"Effect of hexavalent chromium exposure on the pituitary-interrenal axis of a teleost, Channa punctatus (Bloch)","The immunocytochemistry of pituitary corticotrophs, interrenal histopathology and serum cortisol assay revealed adverse effects of hexavalent chromium [Cr(VI)] exposure (as potassium dichromate; K(2)Cr(2)O(7)) on the pituitary-interrenal axis of a freshwater fish, Channa punctatus. On acute exposure (10, 20 and 40 mg L(-1) for 96 h), corticotrophs showed hypertrophy and intense immunoreactivity to anti-human (h) ACTH(1-29). Cytoplasmic degranulations in some of the cells were also noticed. On the contrary, atrophy and weak anti-h ACTH(1-29) immunoreactivity of corticotrophs was observed with the chronic exposure (2 and 4 mg L(-1) for one month). Exposure-dependent varied effects also reflected in the histopathology of head kidney interrenal tissue and serum cortisol levels. Acute exposure induced hypertrophy and degranulation of interrenal cells along with significant elevation of serum cortisol levels in a concentration-dependent manner (42+/-0.72, 44.6+/-1.34 and 52+/-3.06 ng mL(-1), respectively in 10, 20 and 40 mg L(-1) group, compared to 36.65+/-0.83 of control). Atrophy of interrenal cells and low serum cortisol levels as compared to that of control (34.1+/-0.78 and 29.3+/-0.92 ng mL(-1), respectively in 2 and 4 mg L(-1) groups) in chronic-exposed fish indicates attenuated functioning of the hypothalamic-pituitary-interrenal (HPI) axis. The stress response of the fish (under confinement) further confirmed the impairment of the HPI axis, as the elevation in serum cortisol levels were significantly less (258% and 166% of basal level, respectively in 2 and 4 mg L(-1) group, compared to 374% of control). The long-term interference of this axis by metal exposure therefore, may pose serious threat to fish making them unable to adapt to stress.","Effect of hexavalent chromium exposure on the pituitary-interrenal axis of a teleost, Channa punctatus (Bloch) Abs: The immunocytochemistry of pituitary corticotrophs, interrenal histopathology and serum cortisol assay revealed adverse effects of hexavalent chromium [Cr(VI)] exposure (as potassium dichromate; K(2)Cr(2)O(7)) on the pituitary-interrenal axis of a freshwater fish, Channa punctatus. On acute exposure (10, 20 and 40 mg L(-1) for 96 h), corticotrophs showed hypertrophy and intense immunoreactivity to anti-human (h) ACTH(1-29). Cytoplasmic degranulations in some of the cells were also noticed. On the contrary, atrophy and weak anti-h ACTH(1-29) immunoreactivity of corticotrophs was observed with the chronic exposure (2 and 4 mg L(-1) for one month). Exposure-dependent varied effects also reflected in the histopathology of head kidney interrenal tissue and serum cortisol levels. Acute exposure induced hypertrophy and degranulation of interrenal cells along with significant elevation of serum cortisol levels in a concentration-dependent manner (42+/-0.72, 44.6+/-1.34 and 52+/-3.06 ng mL(-1), respectively in 10, 20 and 40 mg L(-1) group, compared to 36.65+/-0.83 of control). Atrophy of interrenal cells and low serum cortisol levels as compared to that of control (34.1+/-0.78 and 29.3+/-0.92 ng mL(-1), respectively in 2 and 4 mg L(-1) groups) in chronic-exposed fish indicates attenuated functioning of the hypothalamic-pituitary-interrenal (HPI) axis. The stress response of the fish (under confinement) further confirmed the impairment of the HPI axis, as the elevation in serum cortisol levels were significantly less (258% and 166% of basal level, respectively in 2 and 4 mg L(-1) group, compared to 374% of control). The long-term interference of this axis by metal exposure therefore, may pose serious threat to fish making them unable to adapt to stress."
1231633,O'Brien et al. 2009,DNA polymerase zeta is essential for hexavalent chromium-induced mutagenesis,"Translesion synthesis (TLS) is a unique DNA damage tolerance mechanism involved in the replicative bypass of genetic lesions in favor of uninterrupted DNA replication. TLS is critical for the generation of mutations by many different chemical and physical agents, however, there is no information available regarding the role of TLS in carcinogenic metal-induced mutagenesis. Hexavalent chromium (Cr(VI))-containing compounds are highly complex genotoxins possessing both mutagenic and clastogenic activities. The focus of this work was to determine the impact that TLS has on Cr(VI)-induced mutagenesis in Saccharomyces cerevisiae. Wild-type yeast and strains deficient in TLS polymerases (i.e. Polzeta (rev3), Poleta (rad30)) were exposed to Cr(VI) and monitored for cell survival and forward mutagenesis at the CAN1 locus. In general, TLS deficiency had little impact on Cr(VI)-induced clonogenic lethality or cell growth. rad30 yeast exhibited higher levels of basal and induced mutagenesis compared to Wt and rev3 yeast. In contrast, rev3 yeast displayed attenuated Cr(VI)-induced mutagenesis. Moreover, deletion of REV3 in rad30 yeast (rad30 rev3) resulted in a significant decrease in basal and Cr(VI) mutagenesis relative to Wt and rad30 single mutants indicating that mutagenesis primarily depended upon Polzeta. Interestingly, rev3 yeast were similar to Wt yeast in susceptibility to Cr(VI)-induced frameshift mutations. Mutational analysis of the CAN1 gene revealed that Cr(VI)-induced base substitution mutations accounted for 83.9% and 100.0% of the total mutations in Wt and rev3 yeast, respectively. Insertions and deletions comprised 16.1% of the total mutations in Cr(VI) treated Wt yeast but were not observed rev3 yeast. This work provides novel information regarding the molecular mechanisms of Cr(VI)-induced mutagenesis and is the first report demonstrating a role for TLS in the fixation of mutations induced by a carcinogenic metal.","DNA polymerase zeta is essential for hexavalent chromium-induced mutagenesis Abs: Translesion synthesis (TLS) is a unique DNA damage tolerance mechanism involved in the replicative bypass of genetic lesions in favor of uninterrupted DNA replication. TLS is critical for the generation of mutations by many different chemical and physical agents, however, there is no information available regarding the role of TLS in carcinogenic metal-induced mutagenesis. Hexavalent chromium (Cr(VI))-containing compounds are highly complex genotoxins possessing both mutagenic and clastogenic activities. The focus of this work was to determine the impact that TLS has on Cr(VI)-induced mutagenesis in Saccharomyces cerevisiae. Wild-type yeast and strains deficient in TLS polymerases (i.e. Polzeta (rev3), Poleta (rad30)) were exposed to Cr(VI) and monitored for cell survival and forward mutagenesis at the CAN1 locus. In general, TLS deficiency had little impact on Cr(VI)-induced clonogenic lethality or cell growth. rad30 yeast exhibited higher levels of basal and induced mutagenesis compared to Wt and rev3 yeast. In contrast, rev3 yeast displayed attenuated Cr(VI)-induced mutagenesis. Moreover, deletion of REV3 in rad30 yeast (rad30 rev3) resulted in a significant decrease in basal and Cr(VI) mutagenesis relative to Wt and rad30 single mutants indicating that mutagenesis primarily depended upon Polzeta. Interestingly, rev3 yeast were similar to Wt yeast in susceptibility to Cr(VI)-induced frameshift mutations. Mutational analysis of the CAN1 gene revealed that Cr(VI)-induced base substitution mutations accounted for 83.9% and 100.0% of the total mutations in Wt and rev3 yeast, respectively. Insertions and deletions comprised 16.1% of the total mutations in Cr(VI) treated Wt yeast but were not observed rev3 yeast. This work provides novel information regarding the molecular mechanisms of Cr(VI)-induced mutagenesis and is the first report demonstrating a role for TLS in the fixation of mutations induced by a carcinogenic metal."
1231632,Li et al. 2009,Hexavalent chromium removal from aqueous solution by adsorption on aluminum magnesium mixed hydroxide,"A series of sols consisting of aluminum magnesium mixed hydroxide (AMH) nanoparticles with various Mg/Al molar ratios were prepared by coprecipitation. The use of AMH as adsorbent to remove Cr(VI) from aqueous solution was investigated. Adsorption experiments were carried out as a function of the Mg/Al molar ratio, pH, contact time, concentration of Cr(VI) and temperature. It was found that AMH with Mg/Al molar ratio 3 has the largest adsorption efficiency due to the smallest average particle diameter and the highest zeta potential; AMH was particularly effective for the Cr(VI) removal in a pH range from acid to slightly alkaline, even though the most effective pH range was between 2.5 and 5.0. The adsorption of Cr(VI) on AMH reached equilibrium within 150 min. The saturated adsorption capacities of AMH for Cr(VI) were 105.3-112.0mg/g at 20-40 degrees C. The interaction between the surface sites of AMH and the Cr(VI) ions may be a combination of both anion exchange and surface complexation. The pseudo-second-order model best described the adsorption kinetics of Cr(VI) onto AMH. The results showed that AMH can be used as a new adsorbent for Cr(VI) removal which has higher adsorption capacity and faster adsorption rate at pH values close to that at which pollutants are usually found in the environment.","Hexavalent chromium removal from aqueous solution by adsorption on aluminum magnesium mixed hydroxide Abs: A series of sols consisting of aluminum magnesium mixed hydroxide (AMH) nanoparticles with various Mg/Al molar ratios were prepared by coprecipitation. The use of AMH as adsorbent to remove Cr(VI) from aqueous solution was investigated. Adsorption experiments were carried out as a function of the Mg/Al molar ratio, pH, contact time, concentration of Cr(VI) and temperature. It was found that AMH with Mg/Al molar ratio 3 has the largest adsorption efficiency due to the smallest average particle diameter and the highest zeta potential; AMH was particularly effective for the Cr(VI) removal in a pH range from acid to slightly alkaline, even though the most effective pH range was between 2.5 and 5.0. The adsorption of Cr(VI) on AMH reached equilibrium within 150 min. The saturated adsorption capacities of AMH for Cr(VI) were 105.3-112.0mg/g at 20-40 degrees C. The interaction between the surface sites of AMH and the Cr(VI) ions may be a combination of both anion exchange and surface complexation. The pseudo-second-order model best described the adsorption kinetics of Cr(VI) onto AMH. The results showed that AMH can be used as a new adsorbent for Cr(VI) removal which has higher adsorption capacity and faster adsorption rate at pH values close to that at which pollutants are usually found in the environment."
1231631,Rivero-Huguet and  Marshall 2009,Reduction of hexavalent chromium mediated by micro- and nano-sized mixed metallic particles,"A variety of micron-scale mixed metallic particles (Pd/Fe, Ag/Fe, Cu/Fe, Zn/Fe, Co/Fe, Mg/Fe, Ni/Fe, Al/Fe, Si/Fe, Pd/Cu and Pd/Zn; and Pd/Cu/Fe, Pd/Zn/Fe and Zn/Cu/Fe) and selected nano-sized bimetallic analogs (Pd/Fe, Cu/Fe and Pd/Cu) were evaluated for reducting activity with Cr(VI) in a surfactant preparation (Tween 20) under a variety of reaction conditions. Relative to the reactivity of the zero-valent iron, the tested bimetallic mixtures (Pd/Fe&gt;Pd/Zn&gt;Ag/Fe&gt;Ni/Fe&gt;Zn/Fe&gt;Pd/Cu&gt;Cu/Fe) appreciably increased the pseudo-first-order rate constant. The Zn/Cu/Fe represented a cost-effective preparation providing comparable or improved kinetic parameters relative to the more expensive palladized bimetallic mixtures. The Pd/Fe, Cu/Fe and Pd/Cu nano-sized particles proved to be more reactive (up to 100-fold) for the reductive remediation of Cr(VI). The results were comparable when working with nano-sized Cu and Fe particles, suggesting that the cementation of a noble metal serves not only as a reaction catalyst but also provides protection to the metallic surface, impeding its rapid inactivation.","Reduction of hexavalent chromium mediated by micro- and nano-sized mixed metallic particles Abs: A variety of micron-scale mixed metallic particles (Pd/Fe, Ag/Fe, Cu/Fe, Zn/Fe, Co/Fe, Mg/Fe, Ni/Fe, Al/Fe, Si/Fe, Pd/Cu and Pd/Zn; and Pd/Cu/Fe, Pd/Zn/Fe and Zn/Cu/Fe) and selected nano-sized bimetallic analogs (Pd/Fe, Cu/Fe and Pd/Cu) were evaluated for reducting activity with Cr(VI) in a surfactant preparation (Tween 20) under a variety of reaction conditions. Relative to the reactivity of the zero-valent iron, the tested bimetallic mixtures (Pd/Fe&gt;Pd/Zn&gt;Ag/Fe&gt;Ni/Fe&gt;Zn/Fe&gt;Pd/Cu&gt;Cu/Fe) appreciably increased the pseudo-first-order rate constant. The Zn/Cu/Fe represented a cost-effective preparation providing comparable or improved kinetic parameters relative to the more expensive palladized bimetallic mixtures. The Pd/Fe, Cu/Fe and Pd/Cu nano-sized particles proved to be more reactive (up to 100-fold) for the reductive remediation of Cr(VI). The results were comparable when working with nano-sized Cu and Fe particles, suggesting that the cementation of a noble metal serves not only as a reaction catalyst but also provides protection to the metallic surface, impeding its rapid inactivation."
1231630,Wang et al. 2009,Diffusion of hexavalent chromium in chromium-containing slag as affected by microbial detoxification,"An electrochemical method was used to determine the diffusion coefficient of chromium(VI) in chromium-containing slag. A slag plate was prepared from the original slag or the detoxified slag by Achromobacter sp. CH-1. The results revealed that the apparent diffusion coefficient of Cr(VI) was 4.4 x 10(-9)m(2)s(-1) in original slag and 2.62 x 10(-8)m(2)s(-1) in detoxified slag. The results implied that detoxification of chromium-containing slag by Achromobacter sp. CH-1 could enhance Cr(VI) release. Meanwhile, the results of laboratory experiment showed that the residual total Cr(VI) in slag decreased from an initial value of 6.8 mg g(-1) to 0.338 mg g(-1) at the end of the detoxification process. The Cr(VI) released from slag was also reduced by Achromobacter sp. CH-1 strain since water soluble Cr(VI) in the leachate was not detected after 4 days. Therefore, Achromobacter sp. CH-1 has potential application for the bio-detoxification of chromium-containing slag.","Diffusion of hexavalent chromium in chromium-containing slag as affected by microbial detoxification Abs: An electrochemical method was used to determine the diffusion coefficient of chromium(VI) in chromium-containing slag. A slag plate was prepared from the original slag or the detoxified slag by Achromobacter sp. CH-1. The results revealed that the apparent diffusion coefficient of Cr(VI) was 4.4 x 10(-9)m(2)s(-1) in original slag and 2.62 x 10(-8)m(2)s(-1) in detoxified slag. The results implied that detoxification of chromium-containing slag by Achromobacter sp. CH-1 could enhance Cr(VI) release. Meanwhile, the results of laboratory experiment showed that the residual total Cr(VI) in slag decreased from an initial value of 6.8 mg g(-1) to 0.338 mg g(-1) at the end of the detoxification process. The Cr(VI) released from slag was also reduced by Achromobacter sp. CH-1 strain since water soluble Cr(VI) in the leachate was not detected after 4 days. Therefore, Achromobacter sp. CH-1 has potential application for the bio-detoxification of chromium-containing slag."
1231629,Arroyo et al. 2009,Effect of pH and chloride concentration on the removal of hexavalent chromium in a batch electrocoagulation reactor,"In this work, the effect of pH and chloride ions concentration on the removal of Cr(VI) from wastewater by batch electrocoagulation using iron plate electrodes has been investigated. The initial solution pH was adjusted with different concentrations of H(2)SO(4). The presence of chloride ions enhances the anode dissolution due to pitting corrosion. Fe(2+) ions formed during the anode dissolution cause the reduction of Cr(VI) to form Cr(III), which are co-precipitated with Fe(3+) ions at relatively low pH. The reduction degree of Cr(VI) to Cr(III) and the solubility of metal hydroxide species (both chromic and iron hydroxides) depend on pH. At higher concentrations of H(2)SO(4), the reduction of Cr(VI) to Cr(III) by Fe(2+) ions is preferred, but the coagulation of Fe(3+) and Cr(III) is favoured at the lower H(2)SO(4) concentrations.","Effect of pH and chloride concentration on the removal of hexavalent chromium in a batch electrocoagulation reactor Abs: In this work, the effect of pH and chloride ions concentration on the removal of Cr(VI) from wastewater by batch electrocoagulation using iron plate electrodes has been investigated. The initial solution pH was adjusted with different concentrations of H(2)SO(4). The presence of chloride ions enhances the anode dissolution due to pitting corrosion. Fe(2+) ions formed during the anode dissolution cause the reduction of Cr(VI) to form Cr(III), which are co-precipitated with Fe(3+) ions at relatively low pH. The reduction degree of Cr(VI) to Cr(III) and the solubility of metal hydroxide species (both chromic and iron hydroxides) depend on pH. At higher concentrations of H(2)SO(4), the reduction of Cr(VI) to Cr(III) by Fe(2+) ions is preferred, but the coagulation of Fe(3+) and Cr(III) is favoured at the lower H(2)SO(4) concentrations."
1231627,Stout et al. 2009,Hexavalent chromium is carcinogenic to F344/N rats and B6C3F1 mice after chronic oral exposure,"<strong>BACKGROUND: </strong>Hexavalent chromium [Cr(VI)] is a human carcinogen after inhalation exposure. Humans also ingest Cr(VI) from contaminated drinking water and soil; however, limited data exist on the oral toxicity and carcinogenicity of Cr(VI).<br /><br /><strong>OBJECTIVE: </strong>We characterized the chronic oral toxicity and carcinogenicity of Cr(VI) in rodents.<br /><br /><strong>METHODS: </strong>The National Toxicology Program (NTP) conducted 2-year drinking water studies of Cr(VI) (as sodium dichromate dihydrate) in male and female F344/N rats and B6C3F1 mice.<br /><br /><strong>RESULTS: </strong>Cr(VI) exposure resulted in increased incidences of rare neoplasms of the squamous epithelium that lines the oral cavity (oral mucosa and tongue) in male and female rats, and of the epithelium lining the small intestine in male and female mice. Cr(VI) exposure did not affect survival but resulted in reduced mean body weights and water consumption, due at least in part to poor palatability of the dosed water. Cr(VI) exposure resulted in transient microcytic hypochromic anemia in rats and microcytosis in mice. Nonneoplastic lesions included diffuse epithelial hyperplasia in the duodenum and jejunum of mice and histiocytic cell infiltration in the duodenum, liver, and mesenteric and pancreatic lymph nodes of rats and mice.<br /><br /><strong>CONCLUSIONS: </strong>Cr(VI) was carcinogenic after administration in drinking water to male and female rats and mice.","Hexavalent chromium is carcinogenic to F344/N rats and B6C3F1 mice after chronic oral exposure Abs: <strong>BACKGROUND: </strong>Hexavalent chromium [Cr(VI)] is a human carcinogen after inhalation exposure. Humans also ingest Cr(VI) from contaminated drinking water and soil; however, limited data exist on the oral toxicity and carcinogenicity of Cr(VI).<br /><br /><strong>OBJECTIVE: </strong>We characterized the chronic oral toxicity and carcinogenicity of Cr(VI) in rodents.<br /><br /><strong>METHODS: </strong>The National Toxicology Program (NTP) conducted 2-year drinking water studies of Cr(VI) (as sodium dichromate dihydrate) in male and female F344/N rats and B6C3F1 mice.<br /><br /><strong>RESULTS: </strong>Cr(VI) exposure resulted in increased incidences of rare neoplasms of the squamous epithelium that lines the oral cavity (oral mucosa and tongue) in male and female rats, and of the epithelium lining the small intestine in male and female mice. Cr(VI) exposure did not affect survival but resulted in reduced mean body weights and water consumption, due at least in part to poor palatability of the dosed water. Cr(VI) exposure resulted in transient microcytic hypochromic anemia in rats and microcytosis in mice. Nonneoplastic lesions included diffuse epithelial hyperplasia in the duodenum and jejunum of mice and histiocytic cell infiltration in the duodenum, liver, and mesenteric and pancreatic lymph nodes of rats and mice.<br /><br /><strong>CONCLUSIONS: </strong>Cr(VI) was carcinogenic after administration in drinking water to male and female rats and mice."
1231626,Mccullough 2009,Selecting respirators for hex chrome exposures,,Selecting respirators for hex chrome exposures Abs: 
1231625,Escudero et al. 2009,Modeling of kinetics of Cr(VI) sorption onto grape stalk waste in a stirred batch reactor,"Recently, Cr(VI) removal by grape stalks has been postulated to follow two mechanisms, adsorption and reduction to trivalent chromium. Nevertheless, the rate at which both processes take place and the possible simultaneity of both processes has not been investigated. In this work, kinetics of Cr(VI) sorption onto grape stalk waste has been studied. Experiments were carried out at different temperatures but at a constant pH (3+/-0.1) in a stirred batch reactor. Results showed that three steps take place in the process of Cr(VI) sorption onto grape stalk waste: Cr(VI) sorption, Cr(VI) reduction to Cr(III) and the adsorption of the formed Cr(III). Taking into account the evidences above mentioned, a model has been developed to predict Cr(VI) sorption on grape stalks on the basis of (i) irreversible reduction of Cr(VI) to Cr(III) reaction, whose reaction rate is assumed to be proportional to the Cr(VI) concentration in solution and (ii) adsorption and desorption of Cr(VI) and formed Cr(III) assuming that all the processes follow Langmuir type kinetics. The proposed model fits successfully the kinetic data obtained at different temperatures and describes the kinetics profile of total, hexavalent and trivalent chromium. The proposed model would be helpful for researchers in the field of Cr(VI) biosorption to design and predict the performance of sorption processes.","Modeling of kinetics of Cr(VI) sorption onto grape stalk waste in a stirred batch reactor Abs: Recently, Cr(VI) removal by grape stalks has been postulated to follow two mechanisms, adsorption and reduction to trivalent chromium. Nevertheless, the rate at which both processes take place and the possible simultaneity of both processes has not been investigated. In this work, kinetics of Cr(VI) sorption onto grape stalk waste has been studied. Experiments were carried out at different temperatures but at a constant pH (3+/-0.1) in a stirred batch reactor. Results showed that three steps take place in the process of Cr(VI) sorption onto grape stalk waste: Cr(VI) sorption, Cr(VI) reduction to Cr(III) and the adsorption of the formed Cr(III). Taking into account the evidences above mentioned, a model has been developed to predict Cr(VI) sorption on grape stalks on the basis of (i) irreversible reduction of Cr(VI) to Cr(III) reaction, whose reaction rate is assumed to be proportional to the Cr(VI) concentration in solution and (ii) adsorption and desorption of Cr(VI) and formed Cr(III) assuming that all the processes follow Langmuir type kinetics. The proposed model fits successfully the kinetic data obtained at different temperatures and describes the kinetics profile of total, hexavalent and trivalent chromium. The proposed model would be helpful for researchers in the field of Cr(VI) biosorption to design and predict the performance of sorption processes."
1231624,Paustenbach 2009,On the chromium reanalysis,,On the chromium reanalysis Abs: 
1231623,Kerger et al. 2009,Chromium(VI) ingestion and cancer,,Chromium(VI) ingestion and cancer Abs: 
1231620,Bansal et al. 2009,A comparative study for the removal of hexavalent chromium from aqueous solution by agriculture wastes' carbons,"This paper reports the feasibility of using agricultural waste and timber industry waste carbons to remove Cr(VI) from synthetic wastewater under different experimental conditions. For this, rice husk and saw dust have been used as adsorbent after sulphuric acid treatment. Effect of various process parameters, namely, pH, adsorbent dose, initial chromium concentration and contact time has been studied in batch systems. Maximum metal removal was observed at pH 2.0. The efficiencies of rice husk carbon (RHC) and saw dust carbon (SDC) for Cr(VI) removal were 91.75% and 94.33%, respectively for aqueous solutions (250 mg L(-1)) at 20 g L(-1) adsorbent dose. The experimental data was analyzed using Freundlich, Langmuir, Dubinin-Redushkevich (D-R) and Temkin isotherm models. It was found that Langmuir, D-R and Temkin models fitted well. The results revealed that the hexavalent chromium is considerably adsorbed on RHC and SDC and it could be an economical method for the removal of hexavalent chromium from aqueous systems. FTIR and SEM of the adsorbents were recorded in native and Cr(VI)-loaded state to explore the number and position of various functional groups available for Cr(VI) binding onto studied adsorbents and changes in adsorbent surface morphology. The surface area of RHC and SDC was 1.12 and 1.16 m(2)g(-1), respectively.","A comparative study for the removal of hexavalent chromium from aqueous solution by agriculture wastes' carbons Abs: This paper reports the feasibility of using agricultural waste and timber industry waste carbons to remove Cr(VI) from synthetic wastewater under different experimental conditions. For this, rice husk and saw dust have been used as adsorbent after sulphuric acid treatment. Effect of various process parameters, namely, pH, adsorbent dose, initial chromium concentration and contact time has been studied in batch systems. Maximum metal removal was observed at pH 2.0. The efficiencies of rice husk carbon (RHC) and saw dust carbon (SDC) for Cr(VI) removal were 91.75% and 94.33%, respectively for aqueous solutions (250 mg L(-1)) at 20 g L(-1) adsorbent dose. The experimental data was analyzed using Freundlich, Langmuir, Dubinin-Redushkevich (D-R) and Temkin isotherm models. It was found that Langmuir, D-R and Temkin models fitted well. The results revealed that the hexavalent chromium is considerably adsorbed on RHC and SDC and it could be an economical method for the removal of hexavalent chromium from aqueous systems. FTIR and SEM of the adsorbents were recorded in native and Cr(VI)-loaded state to explore the number and position of various functional groups available for Cr(VI) binding onto studied adsorbents and changes in adsorbent surface morphology. The surface area of RHC and SDC was 1.12 and 1.16 m(2)g(-1), respectively."
1231619,Wang and  Lo 2009,Synthesis of mesoporous magnetic gamma-Fe2O3 and its application to Cr(VI) removal from contaminated water,"In this study, mesoporous magnetic iron-oxide (gamma-Fe(2)O(3)) was synthesized as an adsorbent for Cr(VI) removal. For material synthesis, mesoporous silica (KIT-6) was used as a hard template and to drive iron precursor into KIT-6, a 'greener', affinity based impregnation method was employed, which involved using a nonpolar solvent (xylene) and led to recycling of the solvent. The results of Cr(VI) removal experiments showed that the synthesized mesoporous gamma-Fe(2)O(3) has a Cr(VI) adsorption capacity comparable with 10nm nonporous gamma-Fe(2)O(3) but simultaneously has a much faster separation than 10nm nonporous gamma-Fe(2)O(3) in the presence of an external magnetic field under the same experimental conditions. Cr(VI) adsorption capacity onto the mesoporous gamma-Fe(2)O(3) increased with decreasing solution pH and could be readily regenerated. Therefore, mesoporous gamma-Fe(2)O(3) presents a reusable adsorbent for a fast, convenient, and highly efficient removal of Cr(VI) from contaminated water.","Synthesis of mesoporous magnetic gamma-Fe2O3 and its application to Cr(VI) removal from contaminated water Abs: In this study, mesoporous magnetic iron-oxide (gamma-Fe(2)O(3)) was synthesized as an adsorbent for Cr(VI) removal. For material synthesis, mesoporous silica (KIT-6) was used as a hard template and to drive iron precursor into KIT-6, a 'greener', affinity based impregnation method was employed, which involved using a nonpolar solvent (xylene) and led to recycling of the solvent. The results of Cr(VI) removal experiments showed that the synthesized mesoporous gamma-Fe(2)O(3) has a Cr(VI) adsorption capacity comparable with 10nm nonporous gamma-Fe(2)O(3) but simultaneously has a much faster separation than 10nm nonporous gamma-Fe(2)O(3) in the presence of an external magnetic field under the same experimental conditions. Cr(VI) adsorption capacity onto the mesoporous gamma-Fe(2)O(3) increased with decreasing solution pH and could be readily regenerated. Therefore, mesoporous gamma-Fe(2)O(3) presents a reusable adsorbent for a fast, convenient, and highly efficient removal of Cr(VI) from contaminated water."
1231618,Rivero-Huguet and  Marshall 2009,Influence of various organic molecules on the reduction of hexavalent chromium mediated by zero-valent iron,"Hexavalent chromium is a priority pollutant in many countries. Reduction of Cr(VI) to Cr(III) is desirable as the latter specie is an essential nutrient for maintaining normal physiological function and also has a low mobility and bioavailability. A variety of naturally-occurring organic molecules (containing alpha-hydroxyl carbonyl, alpha-hydroxyl carboxylate, alpha-carbonyl carboxylate, phenolate, carboxylates and/or thiol groups, siderophore, ascorbic acid); chelating agents (ethylenediaminetetraacetic acid derivates, acetyacetone) and others were examined their reducing activity towards a surfactant preparation (Tween 20) containing Cr(VI) and Fe(0) under a variety of reaction conditions. An appreciable enhancement (up to 50-fold) of the pseudo-first-order rate constant was achieved at acidic and circum neutral pH values for those compounds capable of reducing Cr(VI) (alpha-hydroxyl carboxylate, ascorbic acid, cysteine). Comparable enhancements were obtained for certain chelating agents (ethylenediaminetetraacetic acid derivates and siderophores) which is attributed to the formation of complexes with reaction products, such as Cr(III) and Fe(III), which impede the precipitation of Cr(III) and Fe(III) hydroxides and Cr(x)Fe(1-)(x)(OH)(3) and thus reduce passivation of the Fe(0) surface. The results suggest that these molecules might be used in effective remediation mediated by Fe(0) of Cr(VI)-contaminated soils or groundwater in a wide range of pH, thus increasing reaction rates and long-term performance of permeable reductive barriers.","Influence of various organic molecules on the reduction of hexavalent chromium mediated by zero-valent iron Abs: Hexavalent chromium is a priority pollutant in many countries. Reduction of Cr(VI) to Cr(III) is desirable as the latter specie is an essential nutrient for maintaining normal physiological function and also has a low mobility and bioavailability. A variety of naturally-occurring organic molecules (containing alpha-hydroxyl carbonyl, alpha-hydroxyl carboxylate, alpha-carbonyl carboxylate, phenolate, carboxylates and/or thiol groups, siderophore, ascorbic acid); chelating agents (ethylenediaminetetraacetic acid derivates, acetyacetone) and others were examined their reducing activity towards a surfactant preparation (Tween 20) containing Cr(VI) and Fe(0) under a variety of reaction conditions. An appreciable enhancement (up to 50-fold) of the pseudo-first-order rate constant was achieved at acidic and circum neutral pH values for those compounds capable of reducing Cr(VI) (alpha-hydroxyl carboxylate, ascorbic acid, cysteine). Comparable enhancements were obtained for certain chelating agents (ethylenediaminetetraacetic acid derivates and siderophores) which is attributed to the formation of complexes with reaction products, such as Cr(III) and Fe(III), which impede the precipitation of Cr(III) and Fe(III) hydroxides and Cr(x)Fe(1-)(x)(OH)(3) and thus reduce passivation of the Fe(0) surface. The results suggest that these molecules might be used in effective remediation mediated by Fe(0) of Cr(VI)-contaminated soils or groundwater in a wide range of pH, thus increasing reaction rates and long-term performance of permeable reductive barriers."
1231617,Wood et al. 2010,Eolian transport of geogenic hexavalent chromium to ground water,"A conceptual model of eolian transport is proposed to address the widely distributed, high concentrations of hexavalent chromium (Cr(+6)) observed in ground water in the Emirate of Abu Dhabi, United Arab Emirates. Concentrations (30 to more than 1000 microg/L Cr(+6)) extend over thousands of square kilometers of ground water systems. It is hypothesized that the Cr is derived from weathering of chromium-rich pyroxenes and olivines present in ophiolite sequence of the adjacent Oman (Hajar) Mountains. Cr(+3) in the minerals is oxidized to Cr(+6) by reduction of manganese and is subsequently sorbed on iron and manganese oxide coatings of particles. When the surfaces of these particles are abraded in this arid environment, they release fine, micrometer-sized, coated particles that are easily transported over large distances by wind and subsequently deposited on the surface. During ground water recharge events, the readily soluble Cr(+6) is mobilized by rain water and transported by advective flow into the underlying aquifer. Chromium analyses of ground water, rain, dust, and surface (soil) deposits are consistent with this model, as are electron probe analyses of clasts derived from the eroding Oman ophiolite sequence. Ground water recharge flux is proposed to exercise some control over Cr(+6) concentration in the aquifer.","Eolian transport of geogenic hexavalent chromium to ground water Abs: A conceptual model of eolian transport is proposed to address the widely distributed, high concentrations of hexavalent chromium (Cr(+6)) observed in ground water in the Emirate of Abu Dhabi, United Arab Emirates. Concentrations (30 to more than 1000 microg/L Cr(+6)) extend over thousands of square kilometers of ground water systems. It is hypothesized that the Cr is derived from weathering of chromium-rich pyroxenes and olivines present in ophiolite sequence of the adjacent Oman (Hajar) Mountains. Cr(+3) in the minerals is oxidized to Cr(+6) by reduction of manganese and is subsequently sorbed on iron and manganese oxide coatings of particles. When the surfaces of these particles are abraded in this arid environment, they release fine, micrometer-sized, coated particles that are easily transported over large distances by wind and subsequently deposited on the surface. During ground water recharge events, the readily soluble Cr(+6) is mobilized by rain water and transported by advective flow into the underlying aquifer. Chromium analyses of ground water, rain, dust, and surface (soil) deposits are consistent with this model, as are electron probe analyses of clasts derived from the eroding Oman ophiolite sequence. Ground water recharge flux is proposed to exercise some control over Cr(+6) concentration in the aquifer."
1231616,Nastasovi? et al. 2009,Kinetics of hexavalent chromium sorption on amino-functionalized macroporous glycidyl methacrylate copolymer,"Two samples of macroporous crosslinked poly(glycidyl methacrylate-co-ethylene glycol dimethacrylate), poly(GMA-co-EGDMA), with different porosity parameters were synthesized by suspension copolymerization and functionalized with ethylene diamine and diethylene triamine. The kinetics of Cr(VI) sorption by amino-functionalized poly(GMA-co-EGDMA) was investigated under non-competitive conditions. Competitive kinetics was studied from following multicomponent solutions: Cu(II) and Cr(VI); Cu(II), Co(II), Cd(II) and Ni(II); Cr(VI), Cu(II), Co(II) and Cd(II) solutions. Two kinetic models (the pseudo-first and pseudo-second-order) were used to determine the best-fit equation for the metals sorption by poly(GMA-co-EGDMA)-en and poly(GMA-co-EGDMA)-deta.","Kinetics of hexavalent chromium sorption on amino-functionalized macroporous glycidyl methacrylate copolymer Abs: Two samples of macroporous crosslinked poly(glycidyl methacrylate-co-ethylene glycol dimethacrylate), poly(GMA-co-EGDMA), with different porosity parameters were synthesized by suspension copolymerization and functionalized with ethylene diamine and diethylene triamine. The kinetics of Cr(VI) sorption by amino-functionalized poly(GMA-co-EGDMA) was investigated under non-competitive conditions. Competitive kinetics was studied from following multicomponent solutions: Cu(II) and Cr(VI); Cu(II), Co(II), Cd(II) and Ni(II); Cr(VI), Cu(II), Co(II) and Cd(II) solutions. Two kinetic models (the pseudo-first and pseudo-second-order) were used to determine the best-fit equation for the metals sorption by poly(GMA-co-EGDMA)-en and poly(GMA-co-EGDMA)-deta."
1231615,Aber et al. 2009,Removal of Cr(VI) from polluted solutions by electrocoagulation: Modeling of experimental results using artificial neural network,"In the present work, the removal of Cr(VI) from synthetic and real wastewater using electrocoagulation (EC) process was studied. The influence of anode material, initial Cr(VI) concentration, initial pH of solution, type of electrolyte, current density and time of electrolysis was investigated. During 30 min of electrocoagulation, maximum removal efficiencies achieved by Al and Fe anodes were 0.15 and 0.98, respectively. High removal efficiency was achieved over pH range of 5-8. NaCl, Na(2)SO(4) and NaNO(3) were used as supporting electrolyte during the electrolysis. NaCl was more effective than Na(2)SO(4) and NaNO(3) in removal of hexavalent chromium. Also in this work, a real electroplating wastewater containing 17.1mg/l Cr(VI) was treated successfully using EC process. Artificial neural network (ANN) was utilized for modeling of experimental results. The model was developed using a 3-layer feed forward backpropagation network with 4, 10 and 1 neurons in first, second and third layers, respectively. A comparison between the model results and experimental data gave high correlation coefficient (R(2)=0.976) shows that the model is able to predict the concentration of residual Cr(VI) in the solution.","Removal of Cr(VI) from polluted solutions by electrocoagulation: Modeling of experimental results using artificial neural network Abs: In the present work, the removal of Cr(VI) from synthetic and real wastewater using electrocoagulation (EC) process was studied. The influence of anode material, initial Cr(VI) concentration, initial pH of solution, type of electrolyte, current density and time of electrolysis was investigated. During 30 min of electrocoagulation, maximum removal efficiencies achieved by Al and Fe anodes were 0.15 and 0.98, respectively. High removal efficiency was achieved over pH range of 5-8. NaCl, Na(2)SO(4) and NaNO(3) were used as supporting electrolyte during the electrolysis. NaCl was more effective than Na(2)SO(4) and NaNO(3) in removal of hexavalent chromium. Also in this work, a real electroplating wastewater containing 17.1mg/l Cr(VI) was treated successfully using EC process. Artificial neural network (ANN) was utilized for modeling of experimental results. The model was developed using a 3-layer feed forward backpropagation network with 4, 10 and 1 neurons in first, second and third layers, respectively. A comparison between the model results and experimental data gave high correlation coefficient (R(2)=0.976) shows that the model is able to predict the concentration of residual Cr(VI) in the solution."
1231614,Aceves et al. 2009,Distribution and mobility of Cr in tannery waste amended semi-arid soils under simulated rainfall,"This study was conducted to evaluate the distribution and mobility of Cr in tannery waste that has been added to semi-arid soils. In addition, the amount of total oxidizable soil Cr (III), Cr (VI), pH and soil microbial activities were determined. Tannery sludge alone or mixed with fleshing waste was added to two types of soils, which were then incubated at 25 degrees C for 6 months and subsequently subjected to simulated rainfall. The highest total amount of Cr loss occurred due to infiltration, regardless of the treatments. The Cr loss ranged from 0.452 to 0.825 microg g(-1) soil for all soils from 1 to 3 months, with the exception of those that were located under the canopy and treated with tannery sludge and fleshing waste, which had the highest runoff (from 1.312 to 1.667 microg Crg(-1) soil). The pH of the soil increased from 1 to 3 months (from 7.35 to 8.46), while the total oxidizable soil Cr (III) (2.12-4.31 mg g(-1) soil) peaked after 1 month of treatment. The majority of the fractionated chromium was bound to carbonates at initial time, 3 and 6 months prior to and after application of the simulated rainfall. The microbial activities decreased in each of the treated soils from initial time to 3 months; however, after 6 months bacterial activity increased, while pH decreased (from 8.03 to 7.63). Overall, these data suggest that pH is responsible for Cr loss in response to infiltration and runoff, Cr speciation and the equilibrium of Cr fractionation.","Distribution and mobility of Cr in tannery waste amended semi-arid soils under simulated rainfall Abs: This study was conducted to evaluate the distribution and mobility of Cr in tannery waste that has been added to semi-arid soils. In addition, the amount of total oxidizable soil Cr (III), Cr (VI), pH and soil microbial activities were determined. Tannery sludge alone or mixed with fleshing waste was added to two types of soils, which were then incubated at 25 degrees C for 6 months and subsequently subjected to simulated rainfall. The highest total amount of Cr loss occurred due to infiltration, regardless of the treatments. The Cr loss ranged from 0.452 to 0.825 microg g(-1) soil for all soils from 1 to 3 months, with the exception of those that were located under the canopy and treated with tannery sludge and fleshing waste, which had the highest runoff (from 1.312 to 1.667 microg Crg(-1) soil). The pH of the soil increased from 1 to 3 months (from 7.35 to 8.46), while the total oxidizable soil Cr (III) (2.12-4.31 mg g(-1) soil) peaked after 1 month of treatment. The majority of the fractionated chromium was bound to carbonates at initial time, 3 and 6 months prior to and after application of the simulated rainfall. The microbial activities decreased in each of the treated soils from initial time to 3 months; however, after 6 months bacterial activity increased, while pH decreased (from 8.03 to 7.63). Overall, these data suggest that pH is responsible for Cr loss in response to infiltration and runoff, Cr speciation and the equilibrium of Cr fractionation."
1231613,Hsu et al. 2009,Removal of hexavalent chromium from acidic aqueous solutions using rice straw-derived carbon,"This study evaluates the removal of Cr(VI) from water by carbon derived from the burning of rice straw. Rice straw was burned in the air to obtain rice carbon (RC), and then the removal of Cr(VI) by RC was investigated under various pHs and ionic strengths. After the experiments, the oxidation state of Cr bound to RC was analyzed using X-ray photoelectron spectroscopy, which revealed that Cr bound to RC was predominately in the trivalent form. The results showed that upon reacting with RC, Cr(VI) was reduced to Cr(III), which was either adsorbed on RC or released back into solution. The extent and rate of Cr(VI) removal increased with decreasing solution pH because the Cr(VI) adsorption and the subsequent reduction of adsorbed Cr(VI) to Cr(III) both occur preferentially at low pH. The minimal effect of ionic strength on the rates of Cr(VI) removal and Cr(III) adsorption indicated specific interactions between Cr(VI)/Cr(III) and their surface binding sites on RC. These results suggest that rice straw-based carbon may be effectively used at low pH as a substitute for activated carbon for the treatment of Cr(VI) contaminated water.","Removal of hexavalent chromium from acidic aqueous solutions using rice straw-derived carbon Abs: This study evaluates the removal of Cr(VI) from water by carbon derived from the burning of rice straw. Rice straw was burned in the air to obtain rice carbon (RC), and then the removal of Cr(VI) by RC was investigated under various pHs and ionic strengths. After the experiments, the oxidation state of Cr bound to RC was analyzed using X-ray photoelectron spectroscopy, which revealed that Cr bound to RC was predominately in the trivalent form. The results showed that upon reacting with RC, Cr(VI) was reduced to Cr(III), which was either adsorbed on RC or released back into solution. The extent and rate of Cr(VI) removal increased with decreasing solution pH because the Cr(VI) adsorption and the subsequent reduction of adsorbed Cr(VI) to Cr(III) both occur preferentially at low pH. The minimal effect of ionic strength on the rates of Cr(VI) removal and Cr(III) adsorption indicated specific interactions between Cr(VI)/Cr(III) and their surface binding sites on RC. These results suggest that rice straw-based carbon may be effectively used at low pH as a substitute for activated carbon for the treatment of Cr(VI) contaminated water."
1231612,Uluozlu et al. 2009,Speciation and separation of Cr(VI) and Cr(III) using coprecipitation with Ni2+/2-Nitroso-1-naphthol-4-sulfonic acid and determination by FAAS in water and food samples,"A speciation procedure for chromium(III) and chromium(VI) in the water and food samples has been established in the presented work. The procedure presented based on quantitative recoveries of Cr(III)&gt;95% using coprecipitation of Ni(2+)/2-Nitroso-1-naphthol-4-sulfonic acid. The total chromium was measured after reduction of Cr(VI) by concentrated H(2)SO(4) and ethanol. The Cr(VI) was calculated as the difference between the total Cr content and the Cr(III) contents. The analytical variables, pH, amounts of precipitate, sample volume for optimum recoveries of Cr(III) were investigated. The influences of the some alkaline and earth alkaline ions and some transition metals on the recoveries of analyte ions were also investigated. The preconcentration factor was 50. The detection limit (3 sigma) of the reagent blank for chromium(III) was 1.33 microg L(-1). The relative standard deviations for determinations were found to be &lt;7%, and % of relative error was calculated &lt;6%. The method was validated by certified reference materials of tea (GBW 07605) and bush branches and leaves (GBW 0703). The procedure was successfully applied to the speciation of chromium in natural water and food samples (fish, white cheese, cow's meat, black tea, boiled wheat).","Speciation and separation of Cr(VI) and Cr(III) using coprecipitation with Ni2+/2-Nitroso-1-naphthol-4-sulfonic acid and determination by FAAS in water and food samples Abs: A speciation procedure for chromium(III) and chromium(VI) in the water and food samples has been established in the presented work. The procedure presented based on quantitative recoveries of Cr(III)&gt;95% using coprecipitation of Ni(2+)/2-Nitroso-1-naphthol-4-sulfonic acid. The total chromium was measured after reduction of Cr(VI) by concentrated H(2)SO(4) and ethanol. The Cr(VI) was calculated as the difference between the total Cr content and the Cr(III) contents. The analytical variables, pH, amounts of precipitate, sample volume for optimum recoveries of Cr(III) were investigated. The influences of the some alkaline and earth alkaline ions and some transition metals on the recoveries of analyte ions were also investigated. The preconcentration factor was 50. The detection limit (3 sigma) of the reagent blank for chromium(III) was 1.33 microg L(-1). The relative standard deviations for determinations were found to be &lt;7%, and % of relative error was calculated &lt;6%. The method was validated by certified reference materials of tea (GBW 07605) and bush branches and leaves (GBW 0703). The procedure was successfully applied to the speciation of chromium in natural water and food samples (fish, white cheese, cow's meat, black tea, boiled wheat)."
1231611,Kathiravan et al. 2010,Sonoassisted microbial reduction of chromium,"This study presents sonoassisted microbial reduction of hexavalent chromium (Cr(VI)) using Bacillus sp. isolated from tannery effluent contaminated site. The experiments were carried out with free cells in the presence and absence of ultrasound. The optimum pH and temperature for the reduction of Cr(VI) by Bacillus sp. were found to be 7.0 and 37 degrees C, respectively. The Cr(VI) reduction was significantly influenced by the electron donors and among the various electron donors studied, glucose offered maximum reduction. The ultrasound-irradiated reduction of Cr(VI) with Bacillus sp. showed efficient Cr(VI) reduction. The percent reduction was found to increase with an increase in biomass concentration and decrease with an increase in initial concentration. The changes in the functional groups of Bacillus sp., before and after chromium reduction were observed with FTIR spectra. Microbial growth was described with Monod and Andrews model and best fit was observed with Andrews model.","Sonoassisted microbial reduction of chromium Abs: This study presents sonoassisted microbial reduction of hexavalent chromium (Cr(VI)) using Bacillus sp. isolated from tannery effluent contaminated site. The experiments were carried out with free cells in the presence and absence of ultrasound. The optimum pH and temperature for the reduction of Cr(VI) by Bacillus sp. were found to be 7.0 and 37 degrees C, respectively. The Cr(VI) reduction was significantly influenced by the electron donors and among the various electron donors studied, glucose offered maximum reduction. The ultrasound-irradiated reduction of Cr(VI) with Bacillus sp. showed efficient Cr(VI) reduction. The percent reduction was found to increase with an increase in biomass concentration and decrease with an increase in initial concentration. The changes in the functional groups of Bacillus sp., before and after chromium reduction were observed with FTIR spectra. Microbial growth was described with Monod and Andrews model and best fit was observed with Andrews model."
1231610,Neagu 2009,Removal of Cr(VI) onto functionalized pyridine copolymer with amide groups,"New pyridine strong base anion exchange resin has been prepared by the nucleophilic substitution reaction of 4-vinylpyridine:divinylbenzene copolymer of gel structure with 2-chloroacetamide as halogenated compound. The resulting resin was used to remove Cr(VI) from the aqueous solution. Batch adsorption studies have been carried out to determine the effect of the initial concentration of Cr(VI), adsorbent dose, pH, temperature and the presence of sulfate anions as counter ions. The process was found to be pH, solid/liquid ratio and concentration dependent. The adsorption capacities increase with the increase of the initial concentration of Cr(VI) and therefore, the resin exhibited the degree of usage of the strong base exchange capacities higher than 90% and the good efficiency in the chromium removal. At acidic pH and low concentration of the hexavalent chromium the synthesized pyridine resin offer much greater chromate removal capacities compared to alkaline pH. Equilibrium modeling of the process of Cr(VI) removal was carried out by using the Langmuir and Freundlich isotherms. The experimental data obeyed these isotherm models. Thermodynamic studies were performed and the parameters namely, DeltaG degrees , DeltaH degrees and DeltaS degrees showed the spontaneous and endothermic process of the adsorption of Cr(VI) on the pyridine resin. In the competitive adsorption studies, chromate/sulfate revealed the selectivity of the pyridine adsorbents towards chromium ions. This selectivity is explained by the adsorption of the transition metal anion on the pi bonds of the pyridine ring and the formation a sandwich arrangement with chromium anion and amide functional groups attached to the quaternary nitrogen atoms.","Removal of Cr(VI) onto functionalized pyridine copolymer with amide groups Abs: New pyridine strong base anion exchange resin has been prepared by the nucleophilic substitution reaction of 4-vinylpyridine:divinylbenzene copolymer of gel structure with 2-chloroacetamide as halogenated compound. The resulting resin was used to remove Cr(VI) from the aqueous solution. Batch adsorption studies have been carried out to determine the effect of the initial concentration of Cr(VI), adsorbent dose, pH, temperature and the presence of sulfate anions as counter ions. The process was found to be pH, solid/liquid ratio and concentration dependent. The adsorption capacities increase with the increase of the initial concentration of Cr(VI) and therefore, the resin exhibited the degree of usage of the strong base exchange capacities higher than 90% and the good efficiency in the chromium removal. At acidic pH and low concentration of the hexavalent chromium the synthesized pyridine resin offer much greater chromate removal capacities compared to alkaline pH. Equilibrium modeling of the process of Cr(VI) removal was carried out by using the Langmuir and Freundlich isotherms. The experimental data obeyed these isotherm models. Thermodynamic studies were performed and the parameters namely, DeltaG degrees , DeltaH degrees and DeltaS degrees showed the spontaneous and endothermic process of the adsorption of Cr(VI) on the pyridine resin. In the competitive adsorption studies, chromate/sulfate revealed the selectivity of the pyridine adsorbents towards chromium ions. This selectivity is explained by the adsorption of the transition metal anion on the pi bonds of the pyridine ring and the formation a sandwich arrangement with chromium anion and amide functional groups attached to the quaternary nitrogen atoms."
1231609,Velma et al. 2009,Ecotoxicology of hexavalent chromium in freshwater fish: a critical review,"Chromium (Cr) is a naturally occurring element found in rocks, animals, plants, and soil, predominantly in its insoluble trivalent form [Cr(III)]. Intense industrialization and other anthropogenic activities have led to the global occurrence of soluble hexavalent chromium Cr(VI), which is readily leached from soil to groundwater or surface water, in concentrations above permissible levels. The ecotoxicology of Cr(VI) is linked to its environmental persistence and the ability to induce a variety of adverse effects in biologic systems, including fish. In aquatic ecosystems, Cr(VI) exposure poses a significant threat to aquatic life. This paper reviews the fate and transport of Cr(VI) in the environment and its acute and chronic effects on fish. We also discuss Cr(VI) toxicity at the cellular, biochemical, and genetic levels. An attempt is made in this review to comprehend the staggered data on the toxic effects of Cr(VI) to various species of fish. Such data are extremely useful to the scientific community and public officials involved in health risk assessment and management of environmental contaminants as a guide to the best course of action to restore ecosystems and, in turn, to preserve human health.","Ecotoxicology of hexavalent chromium in freshwater fish: a critical review Abs: Chromium (Cr) is a naturally occurring element found in rocks, animals, plants, and soil, predominantly in its insoluble trivalent form [Cr(III)]. Intense industrialization and other anthropogenic activities have led to the global occurrence of soluble hexavalent chromium Cr(VI), which is readily leached from soil to groundwater or surface water, in concentrations above permissible levels. The ecotoxicology of Cr(VI) is linked to its environmental persistence and the ability to induce a variety of adverse effects in biologic systems, including fish. In aquatic ecosystems, Cr(VI) exposure poses a significant threat to aquatic life. This paper reviews the fate and transport of Cr(VI) in the environment and its acute and chronic effects on fish. We also discuss Cr(VI) toxicity at the cellular, biochemical, and genetic levels. An attempt is made in this review to comprehend the staggered data on the toxic effects of Cr(VI) to various species of fish. Such data are extremely useful to the scientific community and public officials involved in health risk assessment and management of environmental contaminants as a guide to the best course of action to restore ecosystems and, in turn, to preserve human health."
1231607,Kourtev et al. 2009,Inhibition of nitrate reduction by chromium (VI) in anaerobic soil microcosms,"Chromium is often found as a cocontaminant at sites polluted with organic compounds. For nitrate-respiring microbes, Cr(VI) may be not only directly toxic but may also specifically interfere with N reduction. In soil microcosms amended with organic electron donors, Cr(VI), and nitrate, bacteria oxidized added carbon, but relatively low doses of Cr(VI) caused a lag and then lower rates of CO(2) accumulation. Cr(VI) strongly inhibited nitrate reduction; it occurred only after soluble Cr(VI) could not be detected. However, Cr(VI) additions did not eliminate Cr-sensitive populations; after a second dose of Cr(VI), bacterial activity was strongly inhibited. Differences in microbial community composition (assayed by PCR-denaturing gradient gel electrophoresis) driven by different organic substrates (glucose and protein) were smaller than when other electron acceptors had been used. However, the selection of bacterial phylotypes was modified by Cr(VI). Nine isolated clades of facultatively anaerobic Cr(VI)-resistant bacteria were closely related to cultivated members of the phylum Actinobacteria or Firmicutes. In Bacillus cereus GNCR-4, the nature of the electron donor (fermentable or nonfermentable) affected Cr(VI) resistance level and anaerobic nitrate metabolism. Our results indicate that carbon utilization and nitrate reduction in these soils were contingent upon the reduction of added Cr(VI). The amount of Cr(VI) required to inhibit nitrate reduction was 10-fold less than for aerobic catabolism of the same organic substrate. We speculate that the resistance level of a microbial process is directly related to the diversity of microbes capable of conducting it.","Inhibition of nitrate reduction by chromium (VI) in anaerobic soil microcosms Abs: Chromium is often found as a cocontaminant at sites polluted with organic compounds. For nitrate-respiring microbes, Cr(VI) may be not only directly toxic but may also specifically interfere with N reduction. In soil microcosms amended with organic electron donors, Cr(VI), and nitrate, bacteria oxidized added carbon, but relatively low doses of Cr(VI) caused a lag and then lower rates of CO(2) accumulation. Cr(VI) strongly inhibited nitrate reduction; it occurred only after soluble Cr(VI) could not be detected. However, Cr(VI) additions did not eliminate Cr-sensitive populations; after a second dose of Cr(VI), bacterial activity was strongly inhibited. Differences in microbial community composition (assayed by PCR-denaturing gradient gel electrophoresis) driven by different organic substrates (glucose and protein) were smaller than when other electron acceptors had been used. However, the selection of bacterial phylotypes was modified by Cr(VI). Nine isolated clades of facultatively anaerobic Cr(VI)-resistant bacteria were closely related to cultivated members of the phylum Actinobacteria or Firmicutes. In Bacillus cereus GNCR-4, the nature of the electron donor (fermentable or nonfermentable) affected Cr(VI) resistance level and anaerobic nitrate metabolism. Our results indicate that carbon utilization and nitrate reduction in these soils were contingent upon the reduction of added Cr(VI). The amount of Cr(VI) required to inhibit nitrate reduction was 10-fold less than for aerobic catabolism of the same organic substrate. We speculate that the resistance level of a microbial process is directly related to the diversity of microbes capable of conducting it."
1231606,Tang et al. 2009,Adsorption of hexavalent chromium from aqueous solution on raw and modified activated carbon,"Hexavalent chromium [Cr(VI)] is toxic and readily adsorbed by some adsorbents; therefore, its removal from wastewater is extremely important. Batch adsorption of Cr(VI) from aqueous solution using raw and acid-modified activated carbon was investigated in this study. The Cr(VI) sorption was found to be dependent on pH, contact time, initial concentration of solution, adsorbent dose, and temperature. The maximum efficiencies of Cr(VI) removal were 97.67 and 99.87% for activated carbon (AC0) and modified activated carbon (AC1), respectively. The maximum adsorption capacity was found to be 4.75 and 5.95 mg/g for AC0 and AC1, respectively. Thermodynamic parameters indicate that the adsorption process was endothermic and spontaneous in nature. Freundlich adsorption isotherm model was fitted well the equilibrium data for both adsorbents. The Cr(VI) uptake by AC0 and AC1 followed pseudo first-order and second-order kinetics, but was best described by the pseudo second-order rate model. The results also showed that both film diffusion and intraparticle diffusion were concurrently operating, but that intraparticle diffusion controlled the adsorption mechanism.","Adsorption of hexavalent chromium from aqueous solution on raw and modified activated carbon Abs: Hexavalent chromium [Cr(VI)] is toxic and readily adsorbed by some adsorbents; therefore, its removal from wastewater is extremely important. Batch adsorption of Cr(VI) from aqueous solution using raw and acid-modified activated carbon was investigated in this study. The Cr(VI) sorption was found to be dependent on pH, contact time, initial concentration of solution, adsorbent dose, and temperature. The maximum efficiencies of Cr(VI) removal were 97.67 and 99.87% for activated carbon (AC0) and modified activated carbon (AC1), respectively. The maximum adsorption capacity was found to be 4.75 and 5.95 mg/g for AC0 and AC1, respectively. Thermodynamic parameters indicate that the adsorption process was endothermic and spontaneous in nature. Freundlich adsorption isotherm model was fitted well the equilibrium data for both adsorbents. The Cr(VI) uptake by AC0 and AC1 followed pseudo first-order and second-order kinetics, but was best described by the pseudo second-order rate model. The results also showed that both film diffusion and intraparticle diffusion were concurrently operating, but that intraparticle diffusion controlled the adsorption mechanism."
1231605,Somasundaram et al. 2009,"Experimental and mathematical modeling studies on Cr(VI) reduction by CRB, SRB and IRB, individually and in combination","Cr(VI) reduction studies were carried out with chromium reducing bacteria (CRB), sulphate reducing bacteria (SRB) and iron reducing bacteria (IRB), individually and in combination. Biokinetic parameters such as maximum specific growth rate (micro(max)), half saturation constant (K(s)), yield coefficient (Y(T)) and inhibition coefficient (K(i)) for individual cultures were evaluated. A mathematical model was proposed for simulating the chromium reduction, COD utilization and biomass growth, by individual cultures as well as by a combination of two or three different cultures, for different initial Cr(VI), SO(4)(2-) and Fe(III) concentrations. The biokinetic parameters evaluated from one set of experiments for individual cultures were utilized in all the validation studies. The performance of the mathematical model in terms of the dimensionless modified coefficient of efficiency (E) indicated that the proposed model simulates the system behavior very well.","Experimental and mathematical modeling studies on Cr(VI) reduction by CRB, SRB and IRB, individually and in combination Abs: Cr(VI) reduction studies were carried out with chromium reducing bacteria (CRB), sulphate reducing bacteria (SRB) and iron reducing bacteria (IRB), individually and in combination. Biokinetic parameters such as maximum specific growth rate (micro(max)), half saturation constant (K(s)), yield coefficient (Y(T)) and inhibition coefficient (K(i)) for individual cultures were evaluated. A mathematical model was proposed for simulating the chromium reduction, COD utilization and biomass growth, by individual cultures as well as by a combination of two or three different cultures, for different initial Cr(VI), SO(4)(2-) and Fe(III) concentrations. The biokinetic parameters evaluated from one set of experiments for individual cultures were utilized in all the validation studies. The performance of the mathematical model in terms of the dimensionless modified coefficient of efficiency (E) indicated that the proposed model simulates the system behavior very well."
1231604,Bhatti et al. 2009,Electrocoagulation removal of Cr(VI) from simulated wastewater using response surface methodology,"The present study envisages the performance of a laboratory scale electrocoagulation system for the removal of Cr(VI) from 100 mg l(-1) solution using Al-Al electrodes with an effective surface area of 100 cm(2), and placed 15 mm apart. The interaction between voltage x time, and amperage x time best explained the Cr(VI) reduction efficiency with the coefficient of determination (R(2)) being 0.8873 and 0.9270 respectively. Similarly, the square root of energy consumption in Cr(VI) reduction had a linear correlation with voltage x time (R(2)=0.8949), whereas, amperage x time better explained energy consumption (R(2)=0.9400). Response surface methodology was used for the optimization of process variables (pH, voltage and treatment time), response modeling and predictions. Maximum Cr(VI) reduction efficiency of 90.4% was achieved at pH 5, 24 V and 24 min treatment time, and the treatment consumed 137.2 KWh m(-3) of electrical energy. Multiple response optimization for maximizing Cr(VI) reduction efficiency and minimizing energy consumption showed 49.6% Cr(VI) removal at pH 5, 12.8 V and 24 min treatment time. The response models developed explained 95.2% variability for Cr(VI) reduction efficiency and 99.4% variability for energy consumption. Results of the prediction models were validated through laboratory scale batch experiments.","Electrocoagulation removal of Cr(VI) from simulated wastewater using response surface methodology Abs: The present study envisages the performance of a laboratory scale electrocoagulation system for the removal of Cr(VI) from 100 mg l(-1) solution using Al-Al electrodes with an effective surface area of 100 cm(2), and placed 15 mm apart. The interaction between voltage x time, and amperage x time best explained the Cr(VI) reduction efficiency with the coefficient of determination (R(2)) being 0.8873 and 0.9270 respectively. Similarly, the square root of energy consumption in Cr(VI) reduction had a linear correlation with voltage x time (R(2)=0.8949), whereas, amperage x time better explained energy consumption (R(2)=0.9400). Response surface methodology was used for the optimization of process variables (pH, voltage and treatment time), response modeling and predictions. Maximum Cr(VI) reduction efficiency of 90.4% was achieved at pH 5, 24 V and 24 min treatment time, and the treatment consumed 137.2 KWh m(-3) of electrical energy. Multiple response optimization for maximizing Cr(VI) reduction efficiency and minimizing energy consumption showed 49.6% Cr(VI) removal at pH 5, 12.8 V and 24 min treatment time. The response models developed explained 95.2% variability for Cr(VI) reduction efficiency and 99.4% variability for energy consumption. Results of the prediction models were validated through laboratory scale batch experiments."
1231603,Myers and  Myers 2009,The effects of hexavalent chromium on thioredoxin reductase and peroxiredoxins in human bronchial epithelial cells,"Inhalational exposure to hexavalent chromium (Cr(VI)) compounds (e.g., chromates) is of concern in many Cr-related industries and their surrounding environments. The bronchial epithelium is directly exposed to inhaled Cr(VI). Cr(VI) species gain easy access inside cells, where they are reduced to reactive Cr species, which may also contribute to the generation of reactive oxygen species. The thioredoxin (Trx) system promotes cell survival and has a major role in maintaining intracellular thiol redox balance. Previous studies with normal human bronchial epithelial cells (BEAS-2B) demonstrated that chromates cause dose- and time-dependent oxidation of Trx1 and Trx2. The Trx's keep many intracellular proteins reduced, including the peroxiredoxins (Prx's). Prx1 (cytosolic) and Prx3 (mitochondrial) were oxidized by Cr(VI) treatments that oxidized all, or nearly all, of the respective Trx's. Prx oxidation is therefore probably the result of a lack of reducing equivalents from Trx. Trx reductases (TrxR's) keep the Trx's largely in the reduced state. Cr(VI) caused pronounced inhibition of TrxR, but the levels of TrxR protein remained unchanged. The inhibition of TrxR was not reversed by removal of residual Cr(VI) or by NADPH, the endogenous electron donor for TrxR. In contrast, the oxidation of Trx1, Trx2, and Prx3 was reversible by disulfide reductants. Prolonged inhibition of TrxR in Cr(VI)-treated cells might contribute to the sustained oxidation of Trx's and Prx's. Reduced Trx binds to an N-terminal domain of apoptosis signaling kinase (ASK1), keeping ASK1 inactive. Cr(VI) treatments that significantly oxidized Trx1 resulted in pronounced dissociation of Trx1 from ASK1. Overall, the effects of Cr(VI) on the redox state and function of the Trx's, Prx's, and TrxR in the bronchial epithelium could have important implications for redox-sensitive cell signaling and tolerance of oxidant insults.","The effects of hexavalent chromium on thioredoxin reductase and peroxiredoxins in human bronchial epithelial cells Abs: Inhalational exposure to hexavalent chromium (Cr(VI)) compounds (e.g., chromates) is of concern in many Cr-related industries and their surrounding environments. The bronchial epithelium is directly exposed to inhaled Cr(VI). Cr(VI) species gain easy access inside cells, where they are reduced to reactive Cr species, which may also contribute to the generation of reactive oxygen species. The thioredoxin (Trx) system promotes cell survival and has a major role in maintaining intracellular thiol redox balance. Previous studies with normal human bronchial epithelial cells (BEAS-2B) demonstrated that chromates cause dose- and time-dependent oxidation of Trx1 and Trx2. The Trx's keep many intracellular proteins reduced, including the peroxiredoxins (Prx's). Prx1 (cytosolic) and Prx3 (mitochondrial) were oxidized by Cr(VI) treatments that oxidized all, or nearly all, of the respective Trx's. Prx oxidation is therefore probably the result of a lack of reducing equivalents from Trx. Trx reductases (TrxR's) keep the Trx's largely in the reduced state. Cr(VI) caused pronounced inhibition of TrxR, but the levels of TrxR protein remained unchanged. The inhibition of TrxR was not reversed by removal of residual Cr(VI) or by NADPH, the endogenous electron donor for TrxR. In contrast, the oxidation of Trx1, Trx2, and Prx3 was reversible by disulfide reductants. Prolonged inhibition of TrxR in Cr(VI)-treated cells might contribute to the sustained oxidation of Trx's and Prx's. Reduced Trx binds to an N-terminal domain of apoptosis signaling kinase (ASK1), keeping ASK1 inactive. Cr(VI) treatments that significantly oxidized Trx1 resulted in pronounced dissociation of Trx1 from ASK1. Overall, the effects of Cr(VI) on the redox state and function of the Trx's, Prx's, and TrxR in the bronchial epithelium could have important implications for redox-sensitive cell signaling and tolerance of oxidant insults."
1231602,Chrysochoou et al. 2009,Microstructural analyses of Cr(VI) speciation in chromite ore processing residue (COPR),"The speciation and distribution of Cr(VI) in the solid phase was investigated for two types of chromite ore processing residue (COPR) found at two deposition sites in the United States: gray-black (GB) granular and hard brown (HB) cemented COPR. COPR chemistry and mineralogy were investigated using micro-X-ray absorption spectroscopy and micro-X-ray diffraction, complemented by laboratory analyses. GB COPR contained 30% of its total Cr(VI) (6000 mg/kg) as large crystals (&gt;20 microm diameter) of a previously unreported Na-rich analog of calcium aluminum chromate hydrates. These Cr(VI)-rich phases are thought to be vulnerable to reductive and pH treatments. More than 50% of the Cr(VI) was located within nodules, not easily accessible to dissolved reductants, and bound to Fe-rich hydrogarnet, hydrotalcite, and possibly brucite. These phases are stable over a large pH range, thus harder to dissolve. Brownmillerite was also likely associated with physical entrapment of Cr(VI) in the interior of nodules. HB COPR contained no Cr(VI)-rich phases; all Cr(VI) was diffuse within the nodules and absent from the cementing matrix, with hydrogarnet and hydrotalcite being the main Cr(VI) binding phases. Treatment of HB COPR is challenging in terms of dissolving the acidity-resistant, inaccessible Cr(VI) compounds; the same applies to approximately 50% of Cr(VI) in GB COPR.","Microstructural analyses of Cr(VI) speciation in chromite ore processing residue (COPR) Abs: The speciation and distribution of Cr(VI) in the solid phase was investigated for two types of chromite ore processing residue (COPR) found at two deposition sites in the United States: gray-black (GB) granular and hard brown (HB) cemented COPR. COPR chemistry and mineralogy were investigated using micro-X-ray absorption spectroscopy and micro-X-ray diffraction, complemented by laboratory analyses. GB COPR contained 30% of its total Cr(VI) (6000 mg/kg) as large crystals (&gt;20 microm diameter) of a previously unreported Na-rich analog of calcium aluminum chromate hydrates. These Cr(VI)-rich phases are thought to be vulnerable to reductive and pH treatments. More than 50% of the Cr(VI) was located within nodules, not easily accessible to dissolved reductants, and bound to Fe-rich hydrogarnet, hydrotalcite, and possibly brucite. These phases are stable over a large pH range, thus harder to dissolve. Brownmillerite was also likely associated with physical entrapment of Cr(VI) in the interior of nodules. HB COPR contained no Cr(VI)-rich phases; all Cr(VI) was diffuse within the nodules and absent from the cementing matrix, with hydrogarnet and hydrotalcite being the main Cr(VI) binding phases. Treatment of HB COPR is challenging in terms of dissolving the acidity-resistant, inaccessible Cr(VI) compounds; the same applies to approximately 50% of Cr(VI) in GB COPR."
1231601,Sedumedi et al. 2009,Speciation of Cr(VI) in environmental samples in the vicinity of the ferrochrome smelter,"The impact of ferrochrome smelter on the contamination of its environment with toxic hexavalent chromium, Cr(VI), was assessed by analyzing smelter dusts, soil, grass and tree barks. For the separation of Cr(VI) from Cr(III), solid samples were treated with 0.1M Na(2)CO(3) and filtered through hydrophilic PDVF 0.45 microm filter prior to the determination of Cr(VI) by electrothermal atomic absorption spectrometry (ET-AAS). Ferrochrome smelter dust was found to contain significant levels of Cr(VI), viz. 43.5 microg g(-1) (cyclone dust), 2710 microg g(-1) (fine dust), and 7800 microg g(-1) (slimes dust) which exceeded the maximum acceptable risk concentration (20 microg g(-1)). The concentration of Cr(VI) in environmental samples of grass (3.4+/-0.2), soil (7.7+/-0.2), and tree bark (11.8+/-1.2) collected in the vicinity of the chrome smelter were higher as compared with the same kind of samples collected from uncontaminated area. The results of the investigation show that ferrochrome smelter is a source of environmental pollution with contamination factors of Cr(VI) ranging between 10 and 50.","Speciation of Cr(VI) in environmental samples in the vicinity of the ferrochrome smelter Abs: The impact of ferrochrome smelter on the contamination of its environment with toxic hexavalent chromium, Cr(VI), was assessed by analyzing smelter dusts, soil, grass and tree barks. For the separation of Cr(VI) from Cr(III), solid samples were treated with 0.1M Na(2)CO(3) and filtered through hydrophilic PDVF 0.45 microm filter prior to the determination of Cr(VI) by electrothermal atomic absorption spectrometry (ET-AAS). Ferrochrome smelter dust was found to contain significant levels of Cr(VI), viz. 43.5 microg g(-1) (cyclone dust), 2710 microg g(-1) (fine dust), and 7800 microg g(-1) (slimes dust) which exceeded the maximum acceptable risk concentration (20 microg g(-1)). The concentration of Cr(VI) in environmental samples of grass (3.4+/-0.2), soil (7.7+/-0.2), and tree bark (11.8+/-1.2) collected in the vicinity of the chrome smelter were higher as compared with the same kind of samples collected from uncontaminated area. The results of the investigation show that ferrochrome smelter is a source of environmental pollution with contamination factors of Cr(VI) ranging between 10 and 50."
1231600,Lin et al. 2009,Biodegradation of phenol with chromium(VI) reduction in an anaerobic fixed-biofilm process--kinetic model and reactor performance,"A mathematical model system was derived to describe the simultaneous removal of phenol biodegradation with chromium(VI) reduction in an anaerobic fixed-biofilm reactor. The model system incorporates diffusive mass transport and double Monod kinetics. The model was solved using a combination of the orthogonal collocation method and Gear's method. A laboratory-scale column reactor was employed to validate the kinetic model system. Batch kinetic tests were conducted independently to evaluate the biokinetic parameters used in the model simulation. The removal efficiencies of phenol and chromium(VI) in an anaerobic fixed-biofilm process were approximately 980 mg/g and 910 mg/g, respectively, under a steady-state condition. In the steady state, model-predicted biofilm thickness reached up to 350 microm and suspended cells in the effluent were 85 mg cell/l. The experimental results agree closely with the results of the model simulations.","Biodegradation of phenol with chromium(VI) reduction in an anaerobic fixed-biofilm process--kinetic model and reactor performance Abs: A mathematical model system was derived to describe the simultaneous removal of phenol biodegradation with chromium(VI) reduction in an anaerobic fixed-biofilm reactor. The model system incorporates diffusive mass transport and double Monod kinetics. The model was solved using a combination of the orthogonal collocation method and Gear's method. A laboratory-scale column reactor was employed to validate the kinetic model system. Batch kinetic tests were conducted independently to evaluate the biokinetic parameters used in the model simulation. The removal efficiencies of phenol and chromium(VI) in an anaerobic fixed-biofilm process were approximately 980 mg/g and 910 mg/g, respectively, under a steady-state condition. In the steady state, model-predicted biofilm thickness reached up to 350 microm and suspended cells in the effluent were 85 mg cell/l. The experimental results agree closely with the results of the model simulations."
1231599,Wu et al. 2009,Chromium (VI) reduction in aqueous solutions by Fe3O4-stabilized Fe0 nanoparticles,"This paper describes the use of highly reactive magnetite (Fe(3)O(4)) nanoparticles-stabilized Fe(0) nanocomposites for the reduction and mitigation of hexavalent chromium Cr(VI) species in aqueous solutions. Higher proportions of Fe(3)O(4) in the nanocomposites could increase the rate of Cr(VI) reduction. In the absence of magnetite, the Cr(VI) mitigation rate was just 51.4% after 60 min of reaction, while with an initial Fe(3)O(4) mass loading of 3 g l(-1), the Cr(VI) mitigation rate was nearly 100% after 60 min. The optimal ratio of Fe(3)O(4):Fe(0) for the mitigation of Cr(VI) was found to be 40:1. Otherwise, solution pHs significantly affected the rate of Cr(VI) reduction, with reactions occurring more rapidly under acidic or neutral than basic conditions. It is hypothesized that the high efficiency of the Fe(3)O(4) nanoparticles-stabilized Fe(0) nanocomposites for Cr(VI) reduction was a direct result of the attachment of Fe(0) nanoparticles to the surface of magnetite, which prevents the aggregation of nano-Fe(0), moreover, the electron transfer during the reduction process most likely takes place via Fe(0) nanoparticles that are located at the magnetite octahedral sites, which are versatile redox centers as they can accommodate both Fe(III) and Fe(II), and this will promote the reduction of Cr(VI). Cr(VI) reduction is coupled with nano-Fe(0) oxidation. Nano-Fe(0) particles are located at the magnetite octahedral sites. Ions of Fe(II) and Fe(III) accommodated by magnetite octahedral sites are products of nano-Fe(0) oxidation. Therefore, Cr(VI) reduction is mediated either by nano-Fe(0) (direct reduction) or Fe(II) species (indirect reduction). Additionally, catalytic Cr(VI) reduction by molecular H(2) (or atomic H) is possible.","Chromium (VI) reduction in aqueous solutions by Fe3O4-stabilized Fe0 nanoparticles Abs: This paper describes the use of highly reactive magnetite (Fe(3)O(4)) nanoparticles-stabilized Fe(0) nanocomposites for the reduction and mitigation of hexavalent chromium Cr(VI) species in aqueous solutions. Higher proportions of Fe(3)O(4) in the nanocomposites could increase the rate of Cr(VI) reduction. In the absence of magnetite, the Cr(VI) mitigation rate was just 51.4% after 60 min of reaction, while with an initial Fe(3)O(4) mass loading of 3 g l(-1), the Cr(VI) mitigation rate was nearly 100% after 60 min. The optimal ratio of Fe(3)O(4):Fe(0) for the mitigation of Cr(VI) was found to be 40:1. Otherwise, solution pHs significantly affected the rate of Cr(VI) reduction, with reactions occurring more rapidly under acidic or neutral than basic conditions. It is hypothesized that the high efficiency of the Fe(3)O(4) nanoparticles-stabilized Fe(0) nanocomposites for Cr(VI) reduction was a direct result of the attachment of Fe(0) nanoparticles to the surface of magnetite, which prevents the aggregation of nano-Fe(0), moreover, the electron transfer during the reduction process most likely takes place via Fe(0) nanoparticles that are located at the magnetite octahedral sites, which are versatile redox centers as they can accommodate both Fe(III) and Fe(II), and this will promote the reduction of Cr(VI). Cr(VI) reduction is coupled with nano-Fe(0) oxidation. Nano-Fe(0) particles are located at the magnetite octahedral sites. Ions of Fe(II) and Fe(III) accommodated by magnetite octahedral sites are products of nano-Fe(0) oxidation. Therefore, Cr(VI) reduction is mediated either by nano-Fe(0) (direct reduction) or Fe(II) species (indirect reduction). Additionally, catalytic Cr(VI) reduction by molecular H(2) (or atomic H) is possible."
1231598,Ramos-Ramírez et al. 2009,Adsorption isotherm studies of chromium (VI) from aqueous solutions using sol-gel hydrotalcite-like compounds,"In under-developed countries, industries such as paint and pigment manufacturing, leather tanning, chrome plating and textile processing, usually discharge effluents containing Cr(VI) and Cr(III) into municipal sanitary sewers. It has been reported that Cr(VI) acts as a powerful epithelial irritant and as a human carcinogen. In the present work, hydrotalcite-like compounds with a Mg/Al ratio=2 were synthesized by the sol-gel method. The hydrotalcite-like compounds and their corresponding thermally treated products were characterized by powder X-ray diffraction, infrared spectroscopy and N(2) adsorption. The hydrotalcite-like compounds and the heated solids were used as adsorbents for Cr(VI) in aqueous solutions. Adsorption isotherm studies of Cr(VI) from aqueous solution are described. The adsorbent capacity was determined using the Langmuir, Freundlich and Dubinin-Radushkevich adsorption isotherm models. The Cr(VI) adsorption isotherm data fit best to the Langmuir isotherm model. The maximum Cr(VI) uptake by hydrotalcite and the heated solids was determined using the Langmuir equation and was found to range between 26 and 29 mg Cr(VI)/g adsorbent.","Adsorption isotherm studies of chromium (VI) from aqueous solutions using sol-gel hydrotalcite-like compounds Abs: In under-developed countries, industries such as paint and pigment manufacturing, leather tanning, chrome plating and textile processing, usually discharge effluents containing Cr(VI) and Cr(III) into municipal sanitary sewers. It has been reported that Cr(VI) acts as a powerful epithelial irritant and as a human carcinogen. In the present work, hydrotalcite-like compounds with a Mg/Al ratio=2 were synthesized by the sol-gel method. The hydrotalcite-like compounds and their corresponding thermally treated products were characterized by powder X-ray diffraction, infrared spectroscopy and N(2) adsorption. The hydrotalcite-like compounds and the heated solids were used as adsorbents for Cr(VI) in aqueous solutions. Adsorption isotherm studies of Cr(VI) from aqueous solution are described. The adsorbent capacity was determined using the Langmuir, Freundlich and Dubinin-Radushkevich adsorption isotherm models. The Cr(VI) adsorption isotherm data fit best to the Langmuir isotherm model. The maximum Cr(VI) uptake by hydrotalcite and the heated solids was determined using the Langmuir equation and was found to range between 26 and 29 mg Cr(VI)/g adsorbent."
1231597,Yuan et al. 2010,Removal of hexavalent chromium [Cr(VI)] from aqueous solutions by the diatomite-supported/unsupported magnetite nanoparticles,"Diatomite-supported/unsupported magnetite nanoparticles were prepared by co-precipitation and hydrosol methods, and characterized by X-ray diffraction, nitrogen adsorption, elemental analysis, differential scanning calorimetry, transmission electron microscopy and X-ray photoelectron spectroscopy. The average sizes of the unsupported and supported magnetite nanoparticles are around 25 and 15 nm, respectively. The supported magnetite nanoparticles exist on the surface or inside the pores of diatom shells, with better dispersing and less coaggregation than the unsupported ones. The uptake of hexavalent chromium [Cr(VI)] on the synthesized magnetite nanoparticles was mainly governed by a physico-chemical process, which included an electrostatic attraction followed by a redox process in which Cr(VI) was reduced into trivalent chromium [Cr(III)]. The adsorption of Cr(VI) was highly pH-dependent and the kinetics of the adsorption followed a pseudo-second-order model. The adsorption data of diatomite-supported/unsupported magnetite fit well with the Langmuir isotherm equation. The supported magnetite showed a better adsorption capacity per unit mass of magnetite than unsupported magnetite, and was more thermally stable than their unsupported counterparts. These results indicate that the diatomite-supported/unsupported magnetite nanoparticles are readily prepared, enabling promising applications for the removal of Cr(VI) from aqueous solution.","Removal of hexavalent chromium [Cr(VI)] from aqueous solutions by the diatomite-supported/unsupported magnetite nanoparticles Abs: Diatomite-supported/unsupported magnetite nanoparticles were prepared by co-precipitation and hydrosol methods, and characterized by X-ray diffraction, nitrogen adsorption, elemental analysis, differential scanning calorimetry, transmission electron microscopy and X-ray photoelectron spectroscopy. The average sizes of the unsupported and supported magnetite nanoparticles are around 25 and 15 nm, respectively. The supported magnetite nanoparticles exist on the surface or inside the pores of diatom shells, with better dispersing and less coaggregation than the unsupported ones. The uptake of hexavalent chromium [Cr(VI)] on the synthesized magnetite nanoparticles was mainly governed by a physico-chemical process, which included an electrostatic attraction followed by a redox process in which Cr(VI) was reduced into trivalent chromium [Cr(III)]. The adsorption of Cr(VI) was highly pH-dependent and the kinetics of the adsorption followed a pseudo-second-order model. The adsorption data of diatomite-supported/unsupported magnetite fit well with the Langmuir isotherm equation. The supported magnetite showed a better adsorption capacity per unit mass of magnetite than unsupported magnetite, and was more thermally stable than their unsupported counterparts. These results indicate that the diatomite-supported/unsupported magnetite nanoparticles are readily prepared, enabling promising applications for the removal of Cr(VI) from aqueous solution."
1231595,Sahu et al. 2009,Response surface modeling and optimization of chromium(VI) removal from aqueous solution using Tamarind wood activated carbon in batch process,"The present paper discusses response surface methodology (RSM) as an efficient approach for predictive model building and optimization of chromium adsorption on developed activated carbon. In this work the application of RSM is presented for optimizing the removal of Cr(VI) ions from aqua solutions using activated carbon as adsorbent. All experiments were performed according to statistical designs in order to develop the predictive regression models used for optimization. The optimization of adsorption of chromium on activated carbon was carried out to ensure a high adsorption efficiency at low adsorbent dose and high initial concentration of Cr(VI). While the goal of adsorption of chromium optimization was to improve adsorption conditions in batch process, i.e., to minimize the adsorbent dose and to increase the initial concentration of Cr(VI). In the adsorption experiments a laboratory developed Tamarind wood activated carbon made of chemical activation (zinc chloride) was used. A 2(4) full factorial central composite design experimental design was employed. Analysis of variance (ANOVA) showed a high coefficient of determination value (R(2)=0.928) and satisfactory prediction second-order regression model was derived. Maximum chromium removal efficiency was predicted and experimentally validated. The optimum adsorbent dose, temperature, initial concentration of Cr(VI) and initial pH of the Cr(VI) solution were found to be 4.3g/l, 32 degrees C, 20.15 mg/l and 5.41 respectively. Under optimal value of process parameters, high removal (&gt;89%) was obtained for Cr(VI).","Response surface modeling and optimization of chromium(VI) removal from aqueous solution using Tamarind wood activated carbon in batch process Abs: The present paper discusses response surface methodology (RSM) as an efficient approach for predictive model building and optimization of chromium adsorption on developed activated carbon. In this work the application of RSM is presented for optimizing the removal of Cr(VI) ions from aqua solutions using activated carbon as adsorbent. All experiments were performed according to statistical designs in order to develop the predictive regression models used for optimization. The optimization of adsorption of chromium on activated carbon was carried out to ensure a high adsorption efficiency at low adsorbent dose and high initial concentration of Cr(VI). While the goal of adsorption of chromium optimization was to improve adsorption conditions in batch process, i.e., to minimize the adsorbent dose and to increase the initial concentration of Cr(VI). In the adsorption experiments a laboratory developed Tamarind wood activated carbon made of chemical activation (zinc chloride) was used. A 2(4) full factorial central composite design experimental design was employed. Analysis of variance (ANOVA) showed a high coefficient of determination value (R(2)=0.928) and satisfactory prediction second-order regression model was derived. Maximum chromium removal efficiency was predicted and experimentally validated. The optimum adsorbent dose, temperature, initial concentration of Cr(VI) and initial pH of the Cr(VI) solution were found to be 4.3g/l, 32 degrees C, 20.15 mg/l and 5.41 respectively. Under optimal value of process parameters, high removal (&gt;89%) was obtained for Cr(VI)."
1231594,Zhang et al. 2009,Impact of pyrolysis process on the chromium behavior of COPR,"The effect of pyrolysis process with sewage sludge on the chromium behavior of chromite ore processing residue (COPR) was examined in this study. The behavior of chromium was characterized in term of chromium oxidation test, pH-static leaching tests, column leaching test and sequential extraction test. As a sequence of pyrolysis process, the Cr(VI) in COPR was effectively reduced from 5057 mg kg(-1) for untreated COPR to 8.6 mg kg(-1) for treated COPR at temperature over 600 degrees C, which is far below the New Jersey Department of Environmental Protection regulatory limit of 240 mg kg(-1). As a result, the amount of exchangeable and carbonate-bound Cr fractions, the most mobile for the environment, were largely reduced. At the same time, the amount of the other three Cr fractions which are much less mobile become augmented. pH static test showed that the chromium in the treated COPR at pyrolysis temperature above 400 degrees C was quite stable at pH&gt;7. Column study also indicated that only negligible amount of chromium of the treated COPR at above 600 degrees C can be released by the acid rain.","Impact of pyrolysis process on the chromium behavior of COPR Abs: The effect of pyrolysis process with sewage sludge on the chromium behavior of chromite ore processing residue (COPR) was examined in this study. The behavior of chromium was characterized in term of chromium oxidation test, pH-static leaching tests, column leaching test and sequential extraction test. As a sequence of pyrolysis process, the Cr(VI) in COPR was effectively reduced from 5057 mg kg(-1) for untreated COPR to 8.6 mg kg(-1) for treated COPR at temperature over 600 degrees C, which is far below the New Jersey Department of Environmental Protection regulatory limit of 240 mg kg(-1). As a result, the amount of exchangeable and carbonate-bound Cr fractions, the most mobile for the environment, were largely reduced. At the same time, the amount of the other three Cr fractions which are much less mobile become augmented. pH static test showed that the chromium in the treated COPR at pyrolysis temperature above 400 degrees C was quite stable at pH&gt;7. Column study also indicated that only negligible amount of chromium of the treated COPR at above 600 degrees C can be released by the acid rain."
1231593,Decorosi et al. 2009,Characterization of two genes involved in chromate resistance in a Cr(VI)-hyper-resistant bacterium,"Mechanisms underlying chromate resistance in Cr(VI)-hyper-resistant Pseudomonas corrugata strain 28, isolated from a highly Cr(VI) polluted soil, were studied by analyzing its two Cr(VI)-sensitive mutants obtained by insertion mutagenesis. The mutants, namely Crg3 and Crg96, were characterized by the identification of disrupted genes, and by the high-throughput approach called Phenotype MicroArray (PM), which permitted the assay of 1,536 phenotypes simultaneously. Crg3 and Crg96 mutants were affected in a malic enzyme family gene and in a gene encoding for a RecG helicase, respectively. The application of PM provided a wealth of new information relating to the disrupted genes and permitted to establish that chromate resistance in P. corrugata strain 28 also depends on supply on NADPH required in repairing damage induced by chromate and on DNA integrity maintenance.","Characterization of two genes involved in chromate resistance in a Cr(VI)-hyper-resistant bacterium Abs: Mechanisms underlying chromate resistance in Cr(VI)-hyper-resistant Pseudomonas corrugata strain 28, isolated from a highly Cr(VI) polluted soil, were studied by analyzing its two Cr(VI)-sensitive mutants obtained by insertion mutagenesis. The mutants, namely Crg3 and Crg96, were characterized by the identification of disrupted genes, and by the high-throughput approach called Phenotype MicroArray (PM), which permitted the assay of 1,536 phenotypes simultaneously. Crg3 and Crg96 mutants were affected in a malic enzyme family gene and in a gene encoding for a RecG helicase, respectively. The application of PM provided a wealth of new information relating to the disrupted genes and permitted to establish that chromate resistance in P. corrugata strain 28 also depends on supply on NADPH required in repairing damage induced by chromate and on DNA integrity maintenance."
1231592,Venditti et al. 2010,Effects of sulfate ions and slightly acidic pH conditions on Cr(VI) adsorption onto silica gelatin composite,"The feasibility of utilizing CTAB-silica gelatin composite (C-SGC) to remove hexavalent chromium from aqueous solutions under different conditions was investigated. Removal of chromate was assessed through evaluation of the adsorption kinetics of chromate ions on the composite under equilibrium conditions in the presence of sulfate ions and at a slightly acidic pH condition (pH 5.8). Adsorption competition tests in the presence of sulfate ions showed that Cr(VI) was still effectively adsorbed from aqueous solution regardless of the presence of the competing anions. In fact, the adsorption kinetics performed at different initial chromate concentrations were unaffected by the presence of 100 mg L(-1) sulfate ions (pH 7.5). The equilibrium adsorption data were fitted by Freundlich adsorption isotherms which confirmed that the adsorption efficiency of chromium on the CTAB-silica gelatin composite was unchanged in the presence of sulfate ions. Further, the adsorption process was shown to be pH dependent and more efficient at slightly acidic pH (5.8). These findings demonstrated a high specificity of the CTAB-silica gelatin composite for chromium, and highlight the possibility of using this matrix for efficient removal of chromium from industrial wastewater without the need to eliminate contaminant sulfate ions.","Effects of sulfate ions and slightly acidic pH conditions on Cr(VI) adsorption onto silica gelatin composite Abs: The feasibility of utilizing CTAB-silica gelatin composite (C-SGC) to remove hexavalent chromium from aqueous solutions under different conditions was investigated. Removal of chromate was assessed through evaluation of the adsorption kinetics of chromate ions on the composite under equilibrium conditions in the presence of sulfate ions and at a slightly acidic pH condition (pH 5.8). Adsorption competition tests in the presence of sulfate ions showed that Cr(VI) was still effectively adsorbed from aqueous solution regardless of the presence of the competing anions. In fact, the adsorption kinetics performed at different initial chromate concentrations were unaffected by the presence of 100 mg L(-1) sulfate ions (pH 7.5). The equilibrium adsorption data were fitted by Freundlich adsorption isotherms which confirmed that the adsorption efficiency of chromium on the CTAB-silica gelatin composite was unchanged in the presence of sulfate ions. Further, the adsorption process was shown to be pH dependent and more efficient at slightly acidic pH (5.8). These findings demonstrated a high specificity of the CTAB-silica gelatin composite for chromium, and highlight the possibility of using this matrix for efficient removal of chromium from industrial wastewater without the need to eliminate contaminant sulfate ions."
1231589,Cogan et al. 2010,"DNA damaging bystander signalling from stem cells, cancer cells and fibroblasts after Cr(VI) exposure and its dependence on telomerase","The bystander effect is a feature of low dose radiation exposure and is characterized by a signaling process from irradiated cells to non irradiated cells, which causes DNA and chromosome damage in these 'nearest neighbour' cells. Here we show that a low and short dose of Cr(VI) can induce stem cells, cancer cells and fibroblasts to chronically secrete bystander signals, which cause DNA damage in neighboring cells. The Cr(VI) induced bystander signaling depended on the telomerase status of either cell. Telomerase negative fibroblasts were able to receive DNA damaging signals from telomerase positive or negative fibroblasts or telomerase positive cancer cells. However telomerase positive fibroblasts were resistant to signals from Cr(VI) exposed telomerase positive fibroblasts or cancer cells. Human embryonic stem cells, with positive Oct4 staining as a marker of pluripotency, showed no significant increase of DNA damage from adjacent Cr and mitomycin C exposed fibroblasts whilst those cells that were negatively stained did. This selectivity of DNA damaging bystander signaling could be an important consideration in developing therapies against cancer and in the safety and effectiveness of tissue engineering and transplantation using stem cells.","DNA damaging bystander signalling from stem cells, cancer cells and fibroblasts after Cr(VI) exposure and its dependence on telomerase Abs: The bystander effect is a feature of low dose radiation exposure and is characterized by a signaling process from irradiated cells to non irradiated cells, which causes DNA and chromosome damage in these 'nearest neighbour' cells. Here we show that a low and short dose of Cr(VI) can induce stem cells, cancer cells and fibroblasts to chronically secrete bystander signals, which cause DNA damage in neighboring cells. The Cr(VI) induced bystander signaling depended on the telomerase status of either cell. Telomerase negative fibroblasts were able to receive DNA damaging signals from telomerase positive or negative fibroblasts or telomerase positive cancer cells. However telomerase positive fibroblasts were resistant to signals from Cr(VI) exposed telomerase positive fibroblasts or cancer cells. Human embryonic stem cells, with positive Oct4 staining as a marker of pluripotency, showed no significant increase of DNA damage from adjacent Cr and mitomycin C exposed fibroblasts whilst those cells that were negatively stained did. This selectivity of DNA damaging bystander signaling could be an important consideration in developing therapies against cancer and in the safety and effectiveness of tissue engineering and transplantation using stem cells."
1231587,Elci et al. 2010,"Selective extraction of chromium(VI) using a leaching procedure with sodium carbonate from some plant leaves, soil and sediment samples","Speciation of chromium in some plant leaves, soil and sediment samples was carried out by selective leaching of Cr(VI) using a sodium carbonate leaching procedure. Total chromium from the samples was extracted using aqua regia and oxidative acid digestion, respectively. The concentrations of chromium species in the extracts were determined using by graphite furnace atomic absorption spectrometry (GFAAS). Uncoated graphite furnace tubes were used as an atomizer. Due to the presence of relatively high amounts of Na(2)CO(3) in the resulting samples, the possible influences of Na(2)CO(3) on the absorbance signals were checked. There is no interference of Na(2)CO(3) on the chromium absorbance up to 0.1 mol L(-1) Na(2)CO(3). A limit of detection (LOD) for determination of Cr(VI) in 0.1 Na(2)CO(3) solution by GFAAS was found to be 0.93 microg L(-1). The procedure was applied to environmental samples. The relative standard deviation, R.S.D. as precision for 10 replicate measurements of 20 microL(-1) Cr in processed soil sample was 4.2%.","Selective extraction of chromium(VI) using a leaching procedure with sodium carbonate from some plant leaves, soil and sediment samples Abs: Speciation of chromium in some plant leaves, soil and sediment samples was carried out by selective leaching of Cr(VI) using a sodium carbonate leaching procedure. Total chromium from the samples was extracted using aqua regia and oxidative acid digestion, respectively. The concentrations of chromium species in the extracts were determined using by graphite furnace atomic absorption spectrometry (GFAAS). Uncoated graphite furnace tubes were used as an atomizer. Due to the presence of relatively high amounts of Na(2)CO(3) in the resulting samples, the possible influences of Na(2)CO(3) on the absorbance signals were checked. There is no interference of Na(2)CO(3) on the chromium absorbance up to 0.1 mol L(-1) Na(2)CO(3). A limit of detection (LOD) for determination of Cr(VI) in 0.1 Na(2)CO(3) solution by GFAAS was found to be 0.93 microg L(-1). The procedure was applied to environmental samples. The relative standard deviation, R.S.D. as precision for 10 replicate measurements of 20 microL(-1) Cr in processed soil sample was 4.2%."
1231586,Guha et al. 2010,Aqueous extract of Phyllanthus amarus inhibits chromium(VI)-induced toxicity in MDA-MB-435S cells,"Cr(VI) (hexavalent) is a very strong oxidant which causes high cytotoxicity through oxidative stress in tissue systems. Its abundance in groundwater and drinking water in several parts of the world has been noted to cause severe toxicity to both flora and fauna. This study evaluated the effects of aqueous extract of Phyllanthus amarus Schum. &amp; Thon. against Cr(VI)-induced oxidative toxicity in vitro in MDA-MB-435S human breast carcinoma cells, along with an estimation of its antioxidant potential, inhibition of lipid peroxidation and determination of its polyphenolic composition. The extract showed significant (P&lt;0.05) potential in scavenging free radicals (DPPH() and ABTS()(+)) and Fe(+3), and in inhibiting lipid peroxidation. A distinct decline in Cr(VI)-induced cytotoxicity was noticed in MDA-MB-435S cells with an increase in extract dosage. Furthermore, the extract proved to contain a high content of phenolic compounds which were found to have strong and significant (P&lt;0.05) positive correlations to free-radical scavenging potential, lipid peroxidation inhibition capacity and cyto-protective efficiency against Cr(VI)-induced oxidative cellular damage. HPLC analysis identified some of the major phenolic compounds in it. It was concluded that P. amarus aqueous extract has high antioxidant potential (by virtue of its phenolic constituents) which simultaneously inhibits Cr(VI)-induced oxidative toxicity to MDA-MB-435S cells.","Aqueous extract of Phyllanthus amarus inhibits chromium(VI)-induced toxicity in MDA-MB-435S cells Abs: Cr(VI) (hexavalent) is a very strong oxidant which causes high cytotoxicity through oxidative stress in tissue systems. Its abundance in groundwater and drinking water in several parts of the world has been noted to cause severe toxicity to both flora and fauna. This study evaluated the effects of aqueous extract of Phyllanthus amarus Schum. &amp; Thon. against Cr(VI)-induced oxidative toxicity in vitro in MDA-MB-435S human breast carcinoma cells, along with an estimation of its antioxidant potential, inhibition of lipid peroxidation and determination of its polyphenolic composition. The extract showed significant (P&lt;0.05) potential in scavenging free radicals (DPPH() and ABTS()(+)) and Fe(+3), and in inhibiting lipid peroxidation. A distinct decline in Cr(VI)-induced cytotoxicity was noticed in MDA-MB-435S cells with an increase in extract dosage. Furthermore, the extract proved to contain a high content of phenolic compounds which were found to have strong and significant (P&lt;0.05) positive correlations to free-radical scavenging potential, lipid peroxidation inhibition capacity and cyto-protective efficiency against Cr(VI)-induced oxidative cellular damage. HPLC analysis identified some of the major phenolic compounds in it. It was concluded that P. amarus aqueous extract has high antioxidant potential (by virtue of its phenolic constituents) which simultaneously inhibits Cr(VI)-induced oxidative toxicity to MDA-MB-435S cells."
1231585,Macfie et al. 2010,Mechanism of DNA-protein cross-linking by chromium,"Hexavalent chromium is a known inducer of DNA-protein cross-links (DPCs) that contribute to repression of inducible genes and genotoxicity of this metal. Lymphocytic DPCs have also shown potential utility as biomarkers of human exposure to Cr(VI). Here, we examined the mechanism of DPC formation by Cr(VI) and the impact of its main cellular reducers. In vitro reactions of Cr(VI) with one-electron reducing thiols (glutathione and cysteine) or two-electron donating ascorbate were all efficient at DPC production, indicating a dispensable role of Cr(V). No Cr(VI) reducer was able to generate DPC in the presence of Cr(III)-chelating EDTA or phosphate. A critical role of Cr(III) in DNA-protein linkages was further confirmed by dissociation of Cr(VI)-induced DPC by phosphate. EDTA was very inefficient in DPC dissociation, indicating its poor suitability for testing of Cr(III)-mediated bridging and reversal of complex DPC. Reactions containing only one Cr-modified component (protein or DNA) showed that Cr(III)-DNA adduction was the initial step in DPC formation. Cross-linking proceeded slowly after the rapid formation of Cr-DNA adducts, indicating that protein conjugation was the rate-limiting step in DPC generation. Experiments with depletion of glutathione and restoration of ascorbate levels in human lung A549 cells showed that high cellular reducing capacity promotes DPC yield. Overall, our data provide evidence for a three-step cross-linking mechanism involving (i) reduction of Cr(VI) to Cr(III), (ii) Cr(III)-DNA binding, and (iii) protein capture by DNA-bound Cr(III) generating protein-Cr(III)-DNA cross-links.","Mechanism of DNA-protein cross-linking by chromium Abs: Hexavalent chromium is a known inducer of DNA-protein cross-links (DPCs) that contribute to repression of inducible genes and genotoxicity of this metal. Lymphocytic DPCs have also shown potential utility as biomarkers of human exposure to Cr(VI). Here, we examined the mechanism of DPC formation by Cr(VI) and the impact of its main cellular reducers. In vitro reactions of Cr(VI) with one-electron reducing thiols (glutathione and cysteine) or two-electron donating ascorbate were all efficient at DPC production, indicating a dispensable role of Cr(V). No Cr(VI) reducer was able to generate DPC in the presence of Cr(III)-chelating EDTA or phosphate. A critical role of Cr(III) in DNA-protein linkages was further confirmed by dissociation of Cr(VI)-induced DPC by phosphate. EDTA was very inefficient in DPC dissociation, indicating its poor suitability for testing of Cr(III)-mediated bridging and reversal of complex DPC. Reactions containing only one Cr-modified component (protein or DNA) showed that Cr(III)-DNA adduction was the initial step in DPC formation. Cross-linking proceeded slowly after the rapid formation of Cr-DNA adducts, indicating that protein conjugation was the rate-limiting step in DPC generation. Experiments with depletion of glutathione and restoration of ascorbate levels in human lung A549 cells showed that high cellular reducing capacity promotes DPC yield. Overall, our data provide evidence for a three-step cross-linking mechanism involving (i) reduction of Cr(VI) to Cr(III), (ii) Cr(III)-DNA binding, and (iii) protein capture by DNA-bound Cr(III) generating protein-Cr(III)-DNA cross-links."
1231583,Samadi et al. 2009,Adsorption of chromium (VI) from aqueous solution by sugar beet bagasse-based activated charcoal,"Chromium (VI) is known to be potentially carcinogenic and mutagenic in humans. A low-cost industrial solid bioadsorbent, bagasse-based activated charcoal (BAC), has been investigated for removal of chromium from aqueous solution. All the experiments were carried out in batch process with laboratory-prepared samples to study the effects of adsorbent dose, contact time, pH and initial concentration of Cr(VI). The removal of chromium ion was found to be highly dependent on the pH of the solution, adsorbent dose and contact time. Also the equilibrium adsorption was analyzed by the Freundlich and Langmuir isotherm models. It was found that the Freundlich isotherm model best described the sorption of chromium by sugar beet bagasse-based activated charcoal (r2 &gt; 0.9927). Experimental data of kinetic studies were fitted to pseudo-first-order, pseudo-second-order and modified pseudo-first-order models. The results showed pseudo-second order kinetics was best fitted to the collected data (r2 &gt; 0.9893). Optimum conditions for adsorption were determined at pH 2 and a contact time of 180 minutes (92.7% removal). These retention capacities suggest that BAC can provide a simple, effective, and cheap method for removing Cr(VI) ions from effluents and water resources.","Adsorption of chromium (VI) from aqueous solution by sugar beet bagasse-based activated charcoal Abs: Chromium (VI) is known to be potentially carcinogenic and mutagenic in humans. A low-cost industrial solid bioadsorbent, bagasse-based activated charcoal (BAC), has been investigated for removal of chromium from aqueous solution. All the experiments were carried out in batch process with laboratory-prepared samples to study the effects of adsorbent dose, contact time, pH and initial concentration of Cr(VI). The removal of chromium ion was found to be highly dependent on the pH of the solution, adsorbent dose and contact time. Also the equilibrium adsorption was analyzed by the Freundlich and Langmuir isotherm models. It was found that the Freundlich isotherm model best described the sorption of chromium by sugar beet bagasse-based activated charcoal (r2 &gt; 0.9927). Experimental data of kinetic studies were fitted to pseudo-first-order, pseudo-second-order and modified pseudo-first-order models. The results showed pseudo-second order kinetics was best fitted to the collected data (r2 &gt; 0.9893). Optimum conditions for adsorption were determined at pH 2 and a contact time of 180 minutes (92.7% removal). These retention capacities suggest that BAC can provide a simple, effective, and cheap method for removing Cr(VI) ions from effluents and water resources."
1231582,Asatiani et al. 2010,Response of antioxidant defense system to chromium (VI)-induced cytotoxicity in human diploid cells,"The aim of this study is to establish antioxidant indicators of chromium toxicity in fetal human lung fibroblasts (HLF). The results obtained corroborate and develop our earlier observation of low-dose and long-term action of Cr(VI) on human cells in culture. In the case of a nontoxic chromium dose, temporary oxidative stress is overcome by increased activity of the antioxidant system with correlation to cell cycle re-entry. The toxic concentrations misbalance the cell antioxidant defense systems and cause irreversible growth arrest and massive cell death by apoptosis. Sub-toxicity is defined as toxicity stretched in time. The activity of GPx (glutathione peroxidase) is proposed as a biomarker of oxidative stress caused by Cr(VI), and the GR (glutathione reductase) inhibition is considered as a marker of the toxicity developed under the complex Cr(VI) action. In HLF cells the glutathione dependent defense system is the first system destroyed in response to toxic chromium action. Only the balance between SOD (superoxide dismutase) and H(2)O(2) degrading enzymes (catalase and GPx), should play an important role in the fate of a cell, not individual enzymes.","Response of antioxidant defense system to chromium (VI)-induced cytotoxicity in human diploid cells Abs: The aim of this study is to establish antioxidant indicators of chromium toxicity in fetal human lung fibroblasts (HLF). The results obtained corroborate and develop our earlier observation of low-dose and long-term action of Cr(VI) on human cells in culture. In the case of a nontoxic chromium dose, temporary oxidative stress is overcome by increased activity of the antioxidant system with correlation to cell cycle re-entry. The toxic concentrations misbalance the cell antioxidant defense systems and cause irreversible growth arrest and massive cell death by apoptosis. Sub-toxicity is defined as toxicity stretched in time. The activity of GPx (glutathione peroxidase) is proposed as a biomarker of oxidative stress caused by Cr(VI), and the GR (glutathione reductase) inhibition is considered as a marker of the toxicity developed under the complex Cr(VI) action. In HLF cells the glutathione dependent defense system is the first system destroyed in response to toxic chromium action. Only the balance between SOD (superoxide dismutase) and H(2)O(2) degrading enzymes (catalase and GPx), should play an important role in the fate of a cell, not individual enzymes."
1231580,Desimoni and  Brunetti 2009,About estimating the limit of detection of heteroscedastic analytical systems,"The limit of detection is a fundamental figure of merit in chemical analysis. Many different approaches are available for its estimation, but only few allow analysing data characterized by a significant change of precision with concentration. Among these, the ISO 11843-2 approach is certainly the most suitable. However, its implementation may not look easy to operators needing to develop the necessary spreadsheets by commercial software packages. This paper is aimed to verifying if alternative approaches are available for getting acceptably approximate estimates of the limit of detection (LOD). Pragmatically, they were set-up by simply adapting some of the approaches already available in the literature, but compatible only with homoscedastic analytical systems. The results obtained by these alternative approaches when analysing a series of calibrations relevant to the electroanalytical determination of hexavalent chromium in some water samples were compared to those furnished by the ISO approach. The results allowed confirming the critical role of the numerosity of the available data on the consistency of any estimate. Even when using the ISO approach, reliable estimates were only obtained by performing a number of calibrations usually uncommon under standard routine conditions. In such a situation, the differences between the results obtained by all the examined approaches appear less important.","About estimating the limit of detection of heteroscedastic analytical systems Abs: The limit of detection is a fundamental figure of merit in chemical analysis. Many different approaches are available for its estimation, but only few allow analysing data characterized by a significant change of precision with concentration. Among these, the ISO 11843-2 approach is certainly the most suitable. However, its implementation may not look easy to operators needing to develop the necessary spreadsheets by commercial software packages. This paper is aimed to verifying if alternative approaches are available for getting acceptably approximate estimates of the limit of detection (LOD). Pragmatically, they were set-up by simply adapting some of the approaches already available in the literature, but compatible only with homoscedastic analytical systems. The results obtained by these alternative approaches when analysing a series of calibrations relevant to the electroanalytical determination of hexavalent chromium in some water samples were compared to those furnished by the ISO approach. The results allowed confirming the critical role of the numerosity of the available data on the consistency of any estimate. Even when using the ISO approach, reliable estimates were only obtained by performing a number of calibrations usually uncommon under standard routine conditions. In such a situation, the differences between the results obtained by all the examined approaches appear less important."
1231579,Michaels 2010,In response to a review of &quot;Doubt is Their Product&quot,,In response to a review of &quot;Doubt is Their Product&quot Abs: 
1231578,Fiúza et al. 2010,Heterogeneous kinetics of the reduction of chromium (VI) by elemental iron,"Zero valent iron (ZVI) has been extensively used as a reactive medium for the reduction of Cr(VI) to Cr(III) in reactive permeable barriers. The kinetic rate depends strongly on the superficial oxidation of the iron particles used and the preliminary washing of ZVI increases the rate. The reaction has been primarily modelled using a pseudo-first-order kinetics which is inappropriate for a heterogeneous reaction. We assumed a shrinking particle type model where the kinetic rate is proportional to the available iron surface area, to the initial volume of solution and to the chromium concentration raised to a power alpha which is the order of the chemical reaction occurring at surface. We assumed alpha=2/3 based on the likeness to the shrinking particle models with spherical symmetry. Kinetics studies were performed in order to evaluate the suitability of this approach. The influence of the following parameters was experimentally studied: initial available surface area, chromium concentration, temperature and pH. The assumed order for the reaction was confirmed. In addition, the rate constant was calculated from data obtained in different operating conditions. Digital pictures of iron balls were periodically taken and the image treatment allowed for establishing the time evolution of their size distribution.","Heterogeneous kinetics of the reduction of chromium (VI) by elemental iron Abs: Zero valent iron (ZVI) has been extensively used as a reactive medium for the reduction of Cr(VI) to Cr(III) in reactive permeable barriers. The kinetic rate depends strongly on the superficial oxidation of the iron particles used and the preliminary washing of ZVI increases the rate. The reaction has been primarily modelled using a pseudo-first-order kinetics which is inappropriate for a heterogeneous reaction. We assumed a shrinking particle type model where the kinetic rate is proportional to the available iron surface area, to the initial volume of solution and to the chromium concentration raised to a power alpha which is the order of the chemical reaction occurring at surface. We assumed alpha=2/3 based on the likeness to the shrinking particle models with spherical symmetry. Kinetics studies were performed in order to evaluate the suitability of this approach. The influence of the following parameters was experimentally studied: initial available surface area, chromium concentration, temperature and pH. The assumed order for the reaction was confirmed. In addition, the rate constant was calculated from data obtained in different operating conditions. Digital pictures of iron balls were periodically taken and the image treatment allowed for establishing the time evolution of their size distribution."
1231577,Kong and  Ni 2009,Determination of Cr(VI) concentration in diluted samples based on the paper test strip method,"At present, there are many methods for Cr(VI) concentration determination in diluted samples, however, these methods have their own inherent drawbacks, such as long response time, complicated pretreatment, expensive equipment etc. In this paper, a paper-based test strip method specific for determination of diluted Cr(VI) samples was developed. In this method, Aliquat 336, as an anion exchanger was loaded into filter paper to form a test strip. This test strip was used to pre-concentrate Cr(VI) when contacting with the diluted Cr(VI)-containing solution. The Cr(VI)-containing test strip was then immersed into a diphenylcarbazide (DPC) solution (a color forming solution), and the color intensity was correlated to the Cr(VI) concentration. The detection range of the present method was found to be 0.02-1.50 mg/L. The results also showed that the method gave a high selectivity for Cr(VI) in the diluted samples to be tested. The method was applied to synthesized samples and the results, which were compared to those from a reference method, showed that the developed method is an effective, reliable way for Cr(VI) determination in diluted samples.","Determination of Cr(VI) concentration in diluted samples based on the paper test strip method Abs: At present, there are many methods for Cr(VI) concentration determination in diluted samples, however, these methods have their own inherent drawbacks, such as long response time, complicated pretreatment, expensive equipment etc. In this paper, a paper-based test strip method specific for determination of diluted Cr(VI) samples was developed. In this method, Aliquat 336, as an anion exchanger was loaded into filter paper to form a test strip. This test strip was used to pre-concentrate Cr(VI) when contacting with the diluted Cr(VI)-containing solution. The Cr(VI)-containing test strip was then immersed into a diphenylcarbazide (DPC) solution (a color forming solution), and the color intensity was correlated to the Cr(VI) concentration. The detection range of the present method was found to be 0.02-1.50 mg/L. The results also showed that the method gave a high selectivity for Cr(VI) in the diluted samples to be tested. The method was applied to synthesized samples and the results, which were compared to those from a reference method, showed that the developed method is an effective, reliable way for Cr(VI) determination in diluted samples."
1231576,Mu et al. 2010,On the photocatalytic properties of elongated TiO2 nanoparticles for phenol degradation and Cr(VI) reduction,"Elongated TiO(2) nanoparticles with high aspect ratio have specific advantages in separation processes. In this study, TiO(2) nanofiber was prepared via a hydrothermal reaction, and TiO(2) nanoparticles with varied structural properties were obtained using hydrothermal and calcination post-treatments. Photocatalytic phenol degradation and Cr(VI) reduction over these catalysts was investigated. Results showed that hydrothermally prepared TiO(2) nanofiber consisted of titanate with high aspect ratio. Calcining the as-prepared TiO(2) nanofiber at 400 and 600 degrees C led to the crystalline phase transformation from titanate to TiO(2)-B and to the presence of mixed crystalline phases composed of TiO(2)-B and anatase. In contrast, hydrothermal post-treatment results in the generation of pure anatase TiO(2) nanoparticles. For photocatalytic phenol degradation, calcining the as-prepared TiO(2) nanofiber resulted in an enhanced catalytic activity, whereas TiO(2) nanoparticles obtained by calcination post-treatment showed lower catalytic activities for photocatalytic Cr(VI) reduction compared to as-prepared TiO(2) nanofiber. TiO(2) nanofiber modified using the hydrothermal post-treatment, however, exhibited the highest catalytic activity among TiO(2) nanoparticles examined for both photocatalytic phenol degradation and Cr(VI) reduction. Furthermore, TiO(2) nanoparticles obtained by hydrothermal post-treatment showed the best sedimentation efficiency, highlighting its prominent potential as a readily separable and recoverable photocatalyst.","On the photocatalytic properties of elongated TiO2 nanoparticles for phenol degradation and Cr(VI) reduction Abs: Elongated TiO(2) nanoparticles with high aspect ratio have specific advantages in separation processes. In this study, TiO(2) nanofiber was prepared via a hydrothermal reaction, and TiO(2) nanoparticles with varied structural properties were obtained using hydrothermal and calcination post-treatments. Photocatalytic phenol degradation and Cr(VI) reduction over these catalysts was investigated. Results showed that hydrothermally prepared TiO(2) nanofiber consisted of titanate with high aspect ratio. Calcining the as-prepared TiO(2) nanofiber at 400 and 600 degrees C led to the crystalline phase transformation from titanate to TiO(2)-B and to the presence of mixed crystalline phases composed of TiO(2)-B and anatase. In contrast, hydrothermal post-treatment results in the generation of pure anatase TiO(2) nanoparticles. For photocatalytic phenol degradation, calcining the as-prepared TiO(2) nanofiber resulted in an enhanced catalytic activity, whereas TiO(2) nanoparticles obtained by calcination post-treatment showed lower catalytic activities for photocatalytic Cr(VI) reduction compared to as-prepared TiO(2) nanofiber. TiO(2) nanofiber modified using the hydrothermal post-treatment, however, exhibited the highest catalytic activity among TiO(2) nanoparticles examined for both photocatalytic phenol degradation and Cr(VI) reduction. Furthermore, TiO(2) nanoparticles obtained by hydrothermal post-treatment showed the best sedimentation efficiency, highlighting its prominent potential as a readily separable and recoverable photocatalyst."
1231575,Nemec et al. 2010,Chromium(VI) stimulates Fyn to initiate innate immune gene induction in human airway epithelial cells,"Mechanisms for pathogenic metal signaling in airway injury or disease promotion are poorly understood. It is widely believed that one mechanism for pathogenic and possible carcinogenic effects of inhaled chromium (Cr(VI)) is inhibition of inducible gene transactivation. However, we recently reported that Cr(VI) inhibition of Sp1-dependent transactivation required signal transducer and activator of transcription 1 (STAT1)-dependent expression of an inhibitory protein in airway epithelium. Thus, Cr(VI) exposures can induce genes, and we hypothesized that this induction resulted from Cr(VI) signaling through an innate immune-like STAT1-dependent pathway initiated by Fyn. Exposure of human airway epithelial (BEAS-2B) cells to Cr(VI) selectively transactivated the STAT-responsive interferon-stimulated response element (ISRE) and induced ISRE-driven transactivation of interferon regulatory factor 7 (IRF7), without affecting the gamma interferon-activated site (GAS)-driven IRF1 expression. Cr(VI)-induced IRF7 was absent or greatly reduced in cells that lacked STAT1, were treated with the Src family kinase inhibitor, PP2, or lacked Fyn. Expressing Fyn, but not Src, in mouse embryonic fibroblasts cells null for Src, Yes, and Fyn restored Cr(VI)-stimulated STAT1 tyrosine phosphorylation and IRF7 expression. Finally, shRNA knockdown of Fyn in BEAS-2B cells prevented Cr(VI)-activated STAT1 transactivation of IRF7. These data support a novel mechanism through which Cr(VI) stimulates Fyn to initiate interferon-like signaling for STAT1-dependent gene transactivation.","Chromium(VI) stimulates Fyn to initiate innate immune gene induction in human airway epithelial cells Abs: Mechanisms for pathogenic metal signaling in airway injury or disease promotion are poorly understood. It is widely believed that one mechanism for pathogenic and possible carcinogenic effects of inhaled chromium (Cr(VI)) is inhibition of inducible gene transactivation. However, we recently reported that Cr(VI) inhibition of Sp1-dependent transactivation required signal transducer and activator of transcription 1 (STAT1)-dependent expression of an inhibitory protein in airway epithelium. Thus, Cr(VI) exposures can induce genes, and we hypothesized that this induction resulted from Cr(VI) signaling through an innate immune-like STAT1-dependent pathway initiated by Fyn. Exposure of human airway epithelial (BEAS-2B) cells to Cr(VI) selectively transactivated the STAT-responsive interferon-stimulated response element (ISRE) and induced ISRE-driven transactivation of interferon regulatory factor 7 (IRF7), without affecting the gamma interferon-activated site (GAS)-driven IRF1 expression. Cr(VI)-induced IRF7 was absent or greatly reduced in cells that lacked STAT1, were treated with the Src family kinase inhibitor, PP2, or lacked Fyn. Expressing Fyn, but not Src, in mouse embryonic fibroblasts cells null for Src, Yes, and Fyn restored Cr(VI)-stimulated STAT1 tyrosine phosphorylation and IRF7 expression. Finally, shRNA knockdown of Fyn in BEAS-2B cells prevented Cr(VI)-activated STAT1 transactivation of IRF7. These data support a novel mechanism through which Cr(VI) stimulates Fyn to initiate interferon-like signaling for STAT1-dependent gene transactivation."
1231571,Halasova et al. 2009,Human lung cancer and hexavalent chromium exposure,"<strong>OBJECTIVE: </strong>Workers chronically exposed to hexavalent chromium have higher incidence of lung cancer. Our study investigates incidence of lung cancer types, age at onset of the disease and survival time among chromium exposed workers (smelters, tapers, crane operators) in comparison to non-exposed persons.<br /><br /><strong>METHODS: </strong>64 chromium exposed workers and 104 male controls with diagnosed lung cancer were analysed. The average exposure time among workers was 16.71 +/- 10.02 (S.D.) years (range 1- 41 years).<br /><br /><strong>RESULTS: </strong>Chromium exposure significantly decreases the age at the onset of the disease by 3.51 years (62.20 +/- 9.08 years in exposed group and 65.71 +/- 10.50 years in control; P=0.018). Small cell lung carcinoma (SCLC) forms 25.0 % of all cases in chromium exposed workers and 16.34% in non exposed individuals. No correlation was found between the age at the diseases onset and time of exposure. The mean survival time in exposed group was 9.03 +/- 12.73 month, in control 12.14 +/- 21.94 month, but this difference was not significant (P=0.473).<br /><br /><strong>CONCLUSION: </strong>Occupational exposure to chromium was identified as an important risk factor of lung cancer, decreasing the age at the diseases onset. Higher percentage of SCLC was found in chromium exposed individuals.","Human lung cancer and hexavalent chromium exposure Abs: <strong>OBJECTIVE: </strong>Workers chronically exposed to hexavalent chromium have higher incidence of lung cancer. Our study investigates incidence of lung cancer types, age at onset of the disease and survival time among chromium exposed workers (smelters, tapers, crane operators) in comparison to non-exposed persons.<br /><br /><strong>METHODS: </strong>64 chromium exposed workers and 104 male controls with diagnosed lung cancer were analysed. The average exposure time among workers was 16.71 +/- 10.02 (S.D.) years (range 1- 41 years).<br /><br /><strong>RESULTS: </strong>Chromium exposure significantly decreases the age at the onset of the disease by 3.51 years (62.20 +/- 9.08 years in exposed group and 65.71 +/- 10.50 years in control; P=0.018). Small cell lung carcinoma (SCLC) forms 25.0 % of all cases in chromium exposed workers and 16.34% in non exposed individuals. No correlation was found between the age at the diseases onset and time of exposure. The mean survival time in exposed group was 9.03 +/- 12.73 month, in control 12.14 +/- 21.94 month, but this difference was not significant (P=0.473).<br /><br /><strong>CONCLUSION: </strong>Occupational exposure to chromium was identified as an important risk factor of lung cancer, decreasing the age at the diseases onset. Higher percentage of SCLC was found in chromium exposed individuals."
1231570,Lugo-Lugo et al. 2010,Cr(VI) reduction in wastewater using a bimetallic galvanic reactor,"The electrochemical reduction of Cr(VI)-Cr(III) in wastewater by iron and copper-iron bimetallic plates was evaluated and optimized. Iron has been used as a reducing agent, but in this work a copper-iron galvanic system in the form of bimetallic plates is applied to reducing hexavalent chromium. The optimal pH (2) and ratio of copper to iron surface areas (3.5:1) were determined in batch studies, achieving a 100% reduction in about 25 min. The Cr(VI) reduction kinetics for the bimetallic system fit a first order mechanism with a correlation of 0.9935. Thermodynamic analysis shows that the Cr(VI) reduction is possible at any pH value. However, at pH values above 3.0 for iron and 5.5 for chromium insoluble species appear, indicating that the reaction will be hindered. Continuous column studies indicate that the bimetallic copper-iron galvanic system has a reduction capacity of 9.5890 mg Cr(VI) cm(-2) iron, whereas iron alone only has a capacity of 0.1269 mg Cr(VI) cm(-2). The bimetallic copper-iron galvanic system is much more effective in reducing hexavalent chromium than iron alone. The exhausted plates were analyzed by SEM, EDS, and XRD to determine the mechanism and the surface effects, especially surface fouling.","Cr(VI) reduction in wastewater using a bimetallic galvanic reactor Abs: The electrochemical reduction of Cr(VI)-Cr(III) in wastewater by iron and copper-iron bimetallic plates was evaluated and optimized. Iron has been used as a reducing agent, but in this work a copper-iron galvanic system in the form of bimetallic plates is applied to reducing hexavalent chromium. The optimal pH (2) and ratio of copper to iron surface areas (3.5:1) were determined in batch studies, achieving a 100% reduction in about 25 min. The Cr(VI) reduction kinetics for the bimetallic system fit a first order mechanism with a correlation of 0.9935. Thermodynamic analysis shows that the Cr(VI) reduction is possible at any pH value. However, at pH values above 3.0 for iron and 5.5 for chromium insoluble species appear, indicating that the reaction will be hindered. Continuous column studies indicate that the bimetallic copper-iron galvanic system has a reduction capacity of 9.5890 mg Cr(VI) cm(-2) iron, whereas iron alone only has a capacity of 0.1269 mg Cr(VI) cm(-2). The bimetallic copper-iron galvanic system is much more effective in reducing hexavalent chromium than iron alone. The exhausted plates were analyzed by SEM, EDS, and XRD to determine the mechanism and the surface effects, especially surface fouling."
1231568,Costa et al. 2010,Controlled reduction of red mud waste to produce active systems for environmental applications: heterogeneous Fenton reaction and reduction of Cr(VI),"In this work, controlled reduction of red mud with H(2) was used to produce active systems for two different environmental applications, i.e. the heterogeneous Fenton reaction and the reduction of Cr(VI). Mössbauer, powder X-ray diffraction, thermal analyses and scanning electron microscopy analyses showed that at different temperatures, i.e. 300, 400, 500 and 600 degrees C, H(2) reduces red mud to different phases, mainly Fe(3)O(4), Fe(0)/Fe(3)O(4) and Fe(0). These Fe phases are dispersed on Al, Si and Ti oxides present in the red mud and show high reactivity towards two environmental applications, i.e. the heterogeneous Fenton reaction and the reduction of Cr(VI). Reduction with H(2) at 400 degrees C showed the best results for the oxidation of the model dye methylene blue with H(2)O(2) at neutral pH due to the presence of the composite Fe(0)/Fe(3)O(4). The reduced red mud at 500-600 degrees C produced Fe(0) highly active for the reduction of Cr(VI) in aqueous medium. Another feature of these red mud based system is that after deactivation due to extensive use they can be completely regenerated by simple treatment with H(2).","Controlled reduction of red mud waste to produce active systems for environmental applications: heterogeneous Fenton reaction and reduction of Cr(VI) Abs: In this work, controlled reduction of red mud with H(2) was used to produce active systems for two different environmental applications, i.e. the heterogeneous Fenton reaction and the reduction of Cr(VI). Mössbauer, powder X-ray diffraction, thermal analyses and scanning electron microscopy analyses showed that at different temperatures, i.e. 300, 400, 500 and 600 degrees C, H(2) reduces red mud to different phases, mainly Fe(3)O(4), Fe(0)/Fe(3)O(4) and Fe(0). These Fe phases are dispersed on Al, Si and Ti oxides present in the red mud and show high reactivity towards two environmental applications, i.e. the heterogeneous Fenton reaction and the reduction of Cr(VI). Reduction with H(2) at 400 degrees C showed the best results for the oxidation of the model dye methylene blue with H(2)O(2) at neutral pH due to the presence of the composite Fe(0)/Fe(3)O(4). The reduced red mud at 500-600 degrees C produced Fe(0) highly active for the reduction of Cr(VI) in aqueous medium. Another feature of these red mud based system is that after deactivation due to extensive use they can be completely regenerated by simple treatment with H(2)."
1231567,Tiwari et al. 2009,Chromium (VI) induced phytotoxicity and oxidative stress in pea (Pisum sativum L.): biochemical changes and translocation of essential nutrients,"Due to widespread industrial use, chromium (Cr) is considered a hazardous environmental pollutant. It is known to inhibit plant growth and development. The present study provides the evidence of the phytotoxicity of this metal on the pea (Pisum sativum L. cv Azad) plants. The plants of pea (Pisum sativum L.) were grown in refined sand under different concentrations i.e. 0.05, 0.1, 0.2, 0.3 and 0.4 mM of Cr (VI) in order to study the effect on growth and yield, photosynthetic pigments, relative water content, non-reducing sugar and protein with activity of certain enzymes like catalase, peroxidase, starch phosphorylase and ribonuclease. The analysis of the results showed that photosynthetic pigments (68.68%), relative water contents (62.77%), non-reducing sugar (66.66%) and protein (81.57%) were decrease along with reduction in plant height (52.69%) and leaf area (50.81%) of the pea plants. However, in response to various concentration of Cr exposed plants showed significant induction of reducing and total sugars with enzymes like catalase, starch phosphorylase and ribonuclease. The translocation of Cr in various part of pea plant have been found in order of root&gt; stem&gt; leaves&gt;seeds which ranged between 34.8 to 217.3 mg g(-1) d.wt. (dry weight) in roots, 6.5 to 173.13 mg g(-1) d.wt. in shoot, 4.2 to 74.43 mg g(-1) d.wt. in leaves and 0.94 to 8.64 mg g(-1) d.wt. in seeds, that is also reflected by the transfer factor of Cr from refined sand to tested species.","Chromium (VI) induced phytotoxicity and oxidative stress in pea (Pisum sativum L.): biochemical changes and translocation of essential nutrients Abs: Due to widespread industrial use, chromium (Cr) is considered a hazardous environmental pollutant. It is known to inhibit plant growth and development. The present study provides the evidence of the phytotoxicity of this metal on the pea (Pisum sativum L. cv Azad) plants. The plants of pea (Pisum sativum L.) were grown in refined sand under different concentrations i.e. 0.05, 0.1, 0.2, 0.3 and 0.4 mM of Cr (VI) in order to study the effect on growth and yield, photosynthetic pigments, relative water content, non-reducing sugar and protein with activity of certain enzymes like catalase, peroxidase, starch phosphorylase and ribonuclease. The analysis of the results showed that photosynthetic pigments (68.68%), relative water contents (62.77%), non-reducing sugar (66.66%) and protein (81.57%) were decrease along with reduction in plant height (52.69%) and leaf area (50.81%) of the pea plants. However, in response to various concentration of Cr exposed plants showed significant induction of reducing and total sugars with enzymes like catalase, starch phosphorylase and ribonuclease. The translocation of Cr in various part of pea plant have been found in order of root&gt; stem&gt; leaves&gt;seeds which ranged between 34.8 to 217.3 mg g(-1) d.wt. (dry weight) in roots, 6.5 to 173.13 mg g(-1) d.wt. in shoot, 4.2 to 74.43 mg g(-1) d.wt. in leaves and 0.94 to 8.64 mg g(-1) d.wt. in seeds, that is also reflected by the transfer factor of Cr from refined sand to tested species."
1231565,Vignati et al. 2010,Chromium(VI) is more toxic than chromium(III) to freshwater algae: a paradigm to revise?,"The behavior and toxicity of Cr(III) and Cr(VI) to the green algae Pseudokirchneriella subcapitata and Chlorella kessleri were studied in a standard culture medium (ISO medium) and, for P. subcapitata only, in ultrafiltered natural water enriched with all ISO components (modified ISO medium). In all solutions amended with Cr(III), initial chromium concentrations decreased by 60-90% over 72h (the duration of algal tests) indicating that protocols for testing poorly soluble substances are required to properly evaluate Cr(III) toxicity. After accounting for its behavior in test solutions, chromium(III) was 5-10 times more toxic than Cr(VI) in both media. For P. subcapitata, the average 72h EC50 of Cr(III) in ISO medium was 17.4+/-4.7 microg/L (n=9); lower than corresponding hardness-corrected Continuous Concentration Criteria of the US EPA and well within the range of Cr concentrations found in waters impacted by tannery discharges. These results follow from intrinsic chemical properties of Cr(III) in circumneutral solutions, so that the actual toxicity of Cr(III) to aquatic organisms may be generally underestimated.","Chromium(VI) is more toxic than chromium(III) to freshwater algae: a paradigm to revise? Abs: The behavior and toxicity of Cr(III) and Cr(VI) to the green algae Pseudokirchneriella subcapitata and Chlorella kessleri were studied in a standard culture medium (ISO medium) and, for P. subcapitata only, in ultrafiltered natural water enriched with all ISO components (modified ISO medium). In all solutions amended with Cr(III), initial chromium concentrations decreased by 60-90% over 72h (the duration of algal tests) indicating that protocols for testing poorly soluble substances are required to properly evaluate Cr(III) toxicity. After accounting for its behavior in test solutions, chromium(III) was 5-10 times more toxic than Cr(VI) in both media. For P. subcapitata, the average 72h EC50 of Cr(III) in ISO medium was 17.4+/-4.7 microg/L (n=9); lower than corresponding hardness-corrected Continuous Concentration Criteria of the US EPA and well within the range of Cr concentrations found in waters impacted by tannery discharges. These results follow from intrinsic chemical properties of Cr(III) in circumneutral solutions, so that the actual toxicity of Cr(III) to aquatic organisms may be generally underestimated."
1231563,Nancharaiah et al. 2010,Immobilization of Cr(VI) and its reduction to Cr(III) phosphate by granular biofilms comprising a mixture of microbes,"We assessed the potential of mixed microbial consortia, in the form of granular biofilms, to reduce chromate and remove it from synthetic minimal medium. In batch experiments, acetate-fed granular biofilms incubated aerobically reduced 0.2 mM Cr(VI) from a minimal medium at 0.15 mM day(-1) g(-1), with reduction of 0.17 mM day(-1) g(-1) under anaerobic conditions. There was negligible removal of Cr(VI) (i) without granular biofilms, (ii) with lyophilized granular biofilms, and (iii) with granules in the absence of an electron donor. Analyses by X-ray absorption near edge spectroscopy (XANES) of the granular biofilms revealed the conversion of soluble Cr(VI) to Cr(III). Extended X-ray absorption fine-structure (EXAFS) analysis of the Cr-laden granular biofilms demonstrated similarity to Cr(III) phosphate, indicating that Cr(III) was immobilized with phosphate on the biomass subsequent to microbial reduction. The sustained reduction of Cr(VI) by granular biofilms was confirmed in fed-batch experiments. Our study demonstrates the promise of granular-biofilm-based systems in treating Cr(VI)-containing effluents and wastewater.","Immobilization of Cr(VI) and its reduction to Cr(III) phosphate by granular biofilms comprising a mixture of microbes Abs: We assessed the potential of mixed microbial consortia, in the form of granular biofilms, to reduce chromate and remove it from synthetic minimal medium. In batch experiments, acetate-fed granular biofilms incubated aerobically reduced 0.2 mM Cr(VI) from a minimal medium at 0.15 mM day(-1) g(-1), with reduction of 0.17 mM day(-1) g(-1) under anaerobic conditions. There was negligible removal of Cr(VI) (i) without granular biofilms, (ii) with lyophilized granular biofilms, and (iii) with granules in the absence of an electron donor. Analyses by X-ray absorption near edge spectroscopy (XANES) of the granular biofilms revealed the conversion of soluble Cr(VI) to Cr(III). Extended X-ray absorption fine-structure (EXAFS) analysis of the Cr-laden granular biofilms demonstrated similarity to Cr(III) phosphate, indicating that Cr(III) was immobilized with phosphate on the biomass subsequent to microbial reduction. The sustained reduction of Cr(VI) by granular biofilms was confirmed in fed-batch experiments. Our study demonstrates the promise of granular-biofilm-based systems in treating Cr(VI)-containing effluents and wastewater."
1231562,Sun et al. 2010,Sorption and detoxification of chromium(VI) by aerobic granules functionalized with polyethylenimine,"This study describes the modification of aerobic granules by grafting polyethylenimine (PEI) for simultaneous sorption and detoxification of Cr(VI). After modification, the uptake capacity of modified aerobic granules (MAG) showed about 401.5 mg/g at pH 5.5 and increased by 274% compared to the control. Adsorption experiments were carried out as a function of contact time, pH and concentration of Cr(VI). It was found that the equilibrium sorption can be attained within 3 h and the process obeys the Redlich-Peterson isotherm model. The adsorption process is a function of pH of the solution, with the greater adsorption at pH 5.2. The interaction characteristics between the Cr and MAG were elucidated by applying FTIR and XPS analyses. FTIR results showed that the -NH2 groups in the sorbent are involved in the adsorption process. XPS results verified the presence of Cr(III) on the MAG surface in the pH range 1.5-8.5, suggesting that some Cr(VI) anions were reduced to Cr(III) during the sorption.","Sorption and detoxification of chromium(VI) by aerobic granules functionalized with polyethylenimine Abs: This study describes the modification of aerobic granules by grafting polyethylenimine (PEI) for simultaneous sorption and detoxification of Cr(VI). After modification, the uptake capacity of modified aerobic granules (MAG) showed about 401.5 mg/g at pH 5.5 and increased by 274% compared to the control. Adsorption experiments were carried out as a function of contact time, pH and concentration of Cr(VI). It was found that the equilibrium sorption can be attained within 3 h and the process obeys the Redlich-Peterson isotherm model. The adsorption process is a function of pH of the solution, with the greater adsorption at pH 5.2. The interaction characteristics between the Cr and MAG were elucidated by applying FTIR and XPS analyses. FTIR results showed that the -NH2 groups in the sorbent are involved in the adsorption process. XPS results verified the presence of Cr(III) on the MAG surface in the pH range 1.5-8.5, suggesting that some Cr(VI) anions were reduced to Cr(III) during the sorption."
1231561,Dutta et al. 2010,Reduction of hexavalent chromium in aqueous medium with zerovalent iron,"Hexavalent chromium, emanating primarily from the tannery and electroplating industries, can be reduced to the less toxic trivalent variety by several methods, including reduction with metallic iron. In the present work, electrolytic-grade iron dust was used to reduce chromium(VI) in the form of potassium dichromate. Loading of iron dust was varied from 0.5 to 1.0 g in 50 mL of solution; the pH of the medium was varied from 1.5 to 3.5; and the initial concentration of the dichromate solution was varied from 50 to 125 mg/L. Under the specified experimental conditions, maximum removal of the hexavalent chromium achieved was approximately 90% of its original value. The time-concentration data followed a pseudo-first-order kinetic model. The conversion and rate of reduction increased with an increase in iron loading and acidity of the medium, whereas an increase in the initial concentration of chromium(VI) caused a decrease in the reduction.","Reduction of hexavalent chromium in aqueous medium with zerovalent iron Abs: Hexavalent chromium, emanating primarily from the tannery and electroplating industries, can be reduced to the less toxic trivalent variety by several methods, including reduction with metallic iron. In the present work, electrolytic-grade iron dust was used to reduce chromium(VI) in the form of potassium dichromate. Loading of iron dust was varied from 0.5 to 1.0 g in 50 mL of solution; the pH of the medium was varied from 1.5 to 3.5; and the initial concentration of the dichromate solution was varied from 50 to 125 mg/L. Under the specified experimental conditions, maximum removal of the hexavalent chromium achieved was approximately 90% of its original value. The time-concentration data followed a pseudo-first-order kinetic model. The conversion and rate of reduction increased with an increase in iron loading and acidity of the medium, whereas an increase in the initial concentration of chromium(VI) caused a decrease in the reduction."
1231560,Samuel et al. 2011,Lactational hexavalent chromium exposure-induced oxidative stress in rat uterus is associated with delayed puberty and impaired gonadotropin levels,"Hexavalent chromium (CrVI) is a transition element utilized in many fields of modern industries. CrVI is a reproductive metal toxicant that can traverse the placental barrier and cause a wide range of fetal effects. Therefore, the present study was carried out to determine the CrVI-induced utero-toxicity. In the present study, lactating rats received drinking water containing CrVI (50 mg/L and 200 mg/L) from postnatal days (PND) 1-21. During PND 1-21, the pups received CrVI via the mother's milk. Pups from both control and treatment groups were continued on regular diet and water from PND-21 onwards and euthanized on PND-45 and -65. Specific activities antioxidants such as superoxide dismutase (SOD), catalase (CAT), glutathione peroxidase (GPx), glutathione reductase (GR), glutathione-S-transferase (GST) were estimated. Hydrogen peroxide (H?O?), lipid peroxidation (LPO) and serum gonadotropins viz. Luteinizing hormone (LH) and follicle stimulating hormone (FSH) were also assayed. Specific activities of SOD, CAT, GPX, GR and GST and serum testosterone and progesterone were significantly decreased, while H?O?, LPO and serum FSH was increased in 50-parts per million (ppm) and 200 ppm-treated rats in an age-dependent manner. These results suggest that lactational CrVI exposure induces oxidative stress in rat uterus by decreasing antioxidant enzymes, which were associated with delayed puberty and altered steroids and gonadotrophin levels.","Lactational hexavalent chromium exposure-induced oxidative stress in rat uterus is associated with delayed puberty and impaired gonadotropin levels Abs: Hexavalent chromium (CrVI) is a transition element utilized in many fields of modern industries. CrVI is a reproductive metal toxicant that can traverse the placental barrier and cause a wide range of fetal effects. Therefore, the present study was carried out to determine the CrVI-induced utero-toxicity. In the present study, lactating rats received drinking water containing CrVI (50 mg/L and 200 mg/L) from postnatal days (PND) 1-21. During PND 1-21, the pups received CrVI via the mother's milk. Pups from both control and treatment groups were continued on regular diet and water from PND-21 onwards and euthanized on PND-45 and -65. Specific activities antioxidants such as superoxide dismutase (SOD), catalase (CAT), glutathione peroxidase (GPx), glutathione reductase (GR), glutathione-S-transferase (GST) were estimated. Hydrogen peroxide (H?O?), lipid peroxidation (LPO) and serum gonadotropins viz. Luteinizing hormone (LH) and follicle stimulating hormone (FSH) were also assayed. Specific activities of SOD, CAT, GPX, GR and GST and serum testosterone and progesterone were significantly decreased, while H?O?, LPO and serum FSH was increased in 50-parts per million (ppm) and 200 ppm-treated rats in an age-dependent manner. These results suggest that lactational CrVI exposure induces oxidative stress in rat uterus by decreasing antioxidant enzymes, which were associated with delayed puberty and altered steroids and gonadotrophin levels."
1231559,Wise et al. 2010,The cytotoxicity and genotoxicity of hexavalent chromium in Steller sea lion lung fibroblasts compared to human lung fibroblasts,"In this study we directly compared soluble and particulate chromate cytotoxicity and genotoxicity in human (Homo sapiens) and sea lion (Eumetopias jubatus) lung fibroblasts. Our results show that hexavalent chromium induces increased cell death and chromosome damage in both human and sea lion cells with increasing intracellular chromium ion levels. The data further indicate that both sodium chromate and lead chromate are less cytotoxic and genotoxic to sea lion cells than human cells, based on an administered dose. Differences in chromium ion uptake explained some but not all of the reduced amounts of sodium chromate-induced cell death. By contrast, uptake differences could explain the differences in sodium chromate-induced chromosome damage and particulate chromate-induced toxicity. Altogether they indicate that while hexavalent chromium induces similar toxic effects in sea lion and human cells, there are different mechanisms underlying the toxic outcomes.","The cytotoxicity and genotoxicity of hexavalent chromium in Steller sea lion lung fibroblasts compared to human lung fibroblasts Abs: In this study we directly compared soluble and particulate chromate cytotoxicity and genotoxicity in human (Homo sapiens) and sea lion (Eumetopias jubatus) lung fibroblasts. Our results show that hexavalent chromium induces increased cell death and chromosome damage in both human and sea lion cells with increasing intracellular chromium ion levels. The data further indicate that both sodium chromate and lead chromate are less cytotoxic and genotoxic to sea lion cells than human cells, based on an administered dose. Differences in chromium ion uptake explained some but not all of the reduced amounts of sodium chromate-induced cell death. By contrast, uptake differences could explain the differences in sodium chromate-induced chromosome damage and particulate chromate-induced toxicity. Altogether they indicate that while hexavalent chromium induces similar toxic effects in sea lion and human cells, there are different mechanisms underlying the toxic outcomes."
1231558,Son et al. 2010,Cr(VI) induces mitochondrial-mediated and caspase-dependent apoptosis through reactive oxygen species-mediated p53 activation in JB6 Cl41 cells,"Cr(VI) compounds are known to cause serious toxic and carcinogenic effects. Cr(VI) exposure can lead to a severe damage to the skin, but the mechanisms involved in the Cr(VI)-mediated toxicity in the skin are unclear. The present study examined whether Cr(VI) induces cell death by apoptosis or necrosis using mouse skin epidermal cell line, JB6 Cl41 cells. We also investigated the cellular mechanisms of Cr(VI)-induced cell death. This study showed that Cr(VI) induced apoptotic cell death in a dose-dependent manner, as demonstrated by the appearance of cell shrinkage, the migration of cells into the sub-G1 phase, the increase of Annexin V positively stained cells, and the formation of nuclear DNA ladders. Cr(VI) treatment resulted in the increases of mitochondrial membrane depolarization and caspases activation. Electron spin resonance (ESR) and fluorescence analysis revealed that Cr(VI) increased intracellular levels of reactive oxygen species (ROS) such as hydrogen peroxide and superoxide anion radical in dose-dependent manner. Blockage of p53 by si-RNA transfection suppressed mitochondrial changes of Bcl-2 family composition, mitochondrial membrane depolarization, caspase activation and PARP cleavage, leading to the inhibition of Cr(VI)-induced apoptosis. Further, catalase treatment prevented p53 phosphorylation stimulated by Cr(VI) with the concomitant inhibition of caspase activation. These results suggest that Cr(VI) induced a mitochondrial-mediated and caspase-dependent apoptosis in skin epidermal cells through activation of p53, which are mainly mediated by reactive oxidants generated by the chemical.","Cr(VI) induces mitochondrial-mediated and caspase-dependent apoptosis through reactive oxygen species-mediated p53 activation in JB6 Cl41 cells Abs: Cr(VI) compounds are known to cause serious toxic and carcinogenic effects. Cr(VI) exposure can lead to a severe damage to the skin, but the mechanisms involved in the Cr(VI)-mediated toxicity in the skin are unclear. The present study examined whether Cr(VI) induces cell death by apoptosis or necrosis using mouse skin epidermal cell line, JB6 Cl41 cells. We also investigated the cellular mechanisms of Cr(VI)-induced cell death. This study showed that Cr(VI) induced apoptotic cell death in a dose-dependent manner, as demonstrated by the appearance of cell shrinkage, the migration of cells into the sub-G1 phase, the increase of Annexin V positively stained cells, and the formation of nuclear DNA ladders. Cr(VI) treatment resulted in the increases of mitochondrial membrane depolarization and caspases activation. Electron spin resonance (ESR) and fluorescence analysis revealed that Cr(VI) increased intracellular levels of reactive oxygen species (ROS) such as hydrogen peroxide and superoxide anion radical in dose-dependent manner. Blockage of p53 by si-RNA transfection suppressed mitochondrial changes of Bcl-2 family composition, mitochondrial membrane depolarization, caspase activation and PARP cleavage, leading to the inhibition of Cr(VI)-induced apoptosis. Further, catalase treatment prevented p53 phosphorylation stimulated by Cr(VI) with the concomitant inhibition of caspase activation. These results suggest that Cr(VI) induced a mitochondrial-mediated and caspase-dependent apoptosis in skin epidermal cells through activation of p53, which are mainly mediated by reactive oxidants generated by the chemical."
1231557,Wang et al. 2010,Reduction of hexavalent chromium by carboxymethyl cellulose-stabilized zero-valent iron nanoparticles,"The reduction of hexavalent chromium or Cr(VI) by zero-valent iron (Fe(0)) nanoparticles has received increasing attention in recent years. However, Fe(0) nanoparticles prepared using conventional methods suffered several drawbacks due to their high reactivity towards surrounding media, which led to the formation of much larger flocs and significant loss in reactivity. To overcome these problems, we synthesized Fe(0) nanoparticles by applying water-soluble carboxymethyl cellulose (CMC) as a stabilizer. CMC-stabilized Fe(0) nanoparticles displayed much less agglomeration but greater Cr(VI) reduced power than those prepared without a stabilizer. At a dose of 0.15 g L(-)(1), CMC-stabilized Fe(0) nanoparticles were able to reduce 100% of 10 mg L(-)(1) Cr(VI) in minutes. Several factors that may affect the efficiency of Cr(VI) removal were investigated. These included the concentration of CMC, the concentration of Fe(0) nanoparticles, the initial Cr(VI) concentration, the pH value, the reaction temperature and the concentration of the calcium cation in the reaction mixture. Our study suggested that the introduction of an innocuous stabilizer such as CMC could significantly improve the performance of Fe(0) nanoparticles for environmental remediation applications.","Reduction of hexavalent chromium by carboxymethyl cellulose-stabilized zero-valent iron nanoparticles Abs: The reduction of hexavalent chromium or Cr(VI) by zero-valent iron (Fe(0)) nanoparticles has received increasing attention in recent years. However, Fe(0) nanoparticles prepared using conventional methods suffered several drawbacks due to their high reactivity towards surrounding media, which led to the formation of much larger flocs and significant loss in reactivity. To overcome these problems, we synthesized Fe(0) nanoparticles by applying water-soluble carboxymethyl cellulose (CMC) as a stabilizer. CMC-stabilized Fe(0) nanoparticles displayed much less agglomeration but greater Cr(VI) reduced power than those prepared without a stabilizer. At a dose of 0.15 g L(-)(1), CMC-stabilized Fe(0) nanoparticles were able to reduce 100% of 10 mg L(-)(1) Cr(VI) in minutes. Several factors that may affect the efficiency of Cr(VI) removal were investigated. These included the concentration of CMC, the concentration of Fe(0) nanoparticles, the initial Cr(VI) concentration, the pH value, the reaction temperature and the concentration of the calcium cation in the reaction mixture. Our study suggested that the introduction of an innocuous stabilizer such as CMC could significantly improve the performance of Fe(0) nanoparticles for environmental remediation applications."
1231556,Costa et al. 2010,Induction of morphological changes in BEAS-2B human bronchial epithelial cells following chronic sub-cytotoxic and mildly cytotoxic hexavalent chromium exposures,"Certain hexavalent chromium (Cr(VI)) compounds are well established occupational respiratory tract carcinogens. However, despite extensive studies, the cellular and molecular mechanisms underlying Cr(VI)-induced lung cancer remain poorly understood. In fact, the models used were often suboptimal and yielded conflicting results that were heavily dependent upon the system and experimental conditions employed. Here, we investigated the effects of chronic subcytotoxic and mildly cytotoxic (0.1-2 microM) Cr(VI) exposures on cultures of human bronchial epithelial cells, the main targets of Cr(VI) carcinogenicity. Our studies with the nontumorigenic BEAS-2B cell line suggest that relatively short exposures (h) to sublethal Cr(VI) doses (0.1-1 microM) may render these cells less sensitive to contact inhibition. We have also observed a reduced sensitivity to Cr(VI)-induced apoptosis shortly after the beginning of exposure to a mildly cytotoxic Cr(VI) dose (2 microM). Further studies are needed to determine whether these two phenotypes are involved in the Cr(VI)-induced carcinogenic process. Additionally, evidence gathered in this study strongly points to a Cr(VI) interference with cell adhesion to the substratum and with cell-cell interactions. Finally, by chronically exposing BEAS-2B cells to mildly cytotoxic Cr(VI) doses (1 and 2 microM), we were able to induce changes in cell morphology and pattern of growth characteristic of an early phase of pre-malignant progression.","Induction of morphological changes in BEAS-2B human bronchial epithelial cells following chronic sub-cytotoxic and mildly cytotoxic hexavalent chromium exposures Abs: Certain hexavalent chromium (Cr(VI)) compounds are well established occupational respiratory tract carcinogens. However, despite extensive studies, the cellular and molecular mechanisms underlying Cr(VI)-induced lung cancer remain poorly understood. In fact, the models used were often suboptimal and yielded conflicting results that were heavily dependent upon the system and experimental conditions employed. Here, we investigated the effects of chronic subcytotoxic and mildly cytotoxic (0.1-2 microM) Cr(VI) exposures on cultures of human bronchial epithelial cells, the main targets of Cr(VI) carcinogenicity. Our studies with the nontumorigenic BEAS-2B cell line suggest that relatively short exposures (h) to sublethal Cr(VI) doses (0.1-1 microM) may render these cells less sensitive to contact inhibition. We have also observed a reduced sensitivity to Cr(VI)-induced apoptosis shortly after the beginning of exposure to a mildly cytotoxic Cr(VI) dose (2 microM). Further studies are needed to determine whether these two phenotypes are involved in the Cr(VI)-induced carcinogenic process. Additionally, evidence gathered in this study strongly points to a Cr(VI) interference with cell adhesion to the substratum and with cell-cell interactions. Finally, by chronically exposing BEAS-2B cells to mildly cytotoxic Cr(VI) doses (1 and 2 microM), we were able to induce changes in cell morphology and pattern of growth characteristic of an early phase of pre-malignant progression."
1231555,Velma and  Tchounwou 2010,"Chromium-induced biochemical, genotoxic and histopathologic effects in liver and kidney of goldfish, carassius auratus","Fish constitute an excellent model to understand the mechanistic aspects of metal toxicity vis-à-vis oxidative stress in aquatic ecosystems. Hexavalent chromium (Cr (VI)), due to its redox potential can induce oxidative stress (OS) in fish and impair their health. In the present investigation, we hypothesize that OS plays a key role in chromium induced toxicity in goldfish; leading to the production of reactive oxygen species (ROS) such as O(.)(2), H(2)O(2), OH(.), and subsequent modulation of the activities of antioxidant enzymes such as catalase (CAT), superoxide dismutase (SOD), metallothioneins (MT), glutathione proxidase (GPx), genotoxicity and histopathology. To test this hypothesis, antioxidant enzymes, DNA damage and histopathology assays were performed in liver and kidney tissues of goldfish exposed to different concentrations of Cr (VI) (LC(12.5), LC(25) and LC(50)) following 96h static renewal bioassay. The results of this study clearly show that the fish experienced OS as characterized by significant modulation of enzyme activities, induction of DNA damage and microscopic morphological changes in the liver and kidney. In both tissues, CAT activity was decreased whereas SOD activity and hydroperoxide levels were increased. In addition, GPx activity also increased significantly in higher test concentrations, especially in the kidney. MT induction and DNA damage were observed in both tissues in a concentration dependent manner. Microscopic examination of organ morphology indicated degeneration of liver tissue and necrosis of central vein. Necrosis of kidney tubular epithelial cells and tubules was observed at higher Cr (VI) concentrations. Taking together the findings of this study are helpful in organ-specific risk assessment of Cr (VI)-induced oxidative stress, genotoxicity and histopathology in fish.","Chromium-induced biochemical, genotoxic and histopathologic effects in liver and kidney of goldfish, carassius auratus Abs: Fish constitute an excellent model to understand the mechanistic aspects of metal toxicity vis-à-vis oxidative stress in aquatic ecosystems. Hexavalent chromium (Cr (VI)), due to its redox potential can induce oxidative stress (OS) in fish and impair their health. In the present investigation, we hypothesize that OS plays a key role in chromium induced toxicity in goldfish; leading to the production of reactive oxygen species (ROS) such as O(.)(2), H(2)O(2), OH(.), and subsequent modulation of the activities of antioxidant enzymes such as catalase (CAT), superoxide dismutase (SOD), metallothioneins (MT), glutathione proxidase (GPx), genotoxicity and histopathology. To test this hypothesis, antioxidant enzymes, DNA damage and histopathology assays were performed in liver and kidney tissues of goldfish exposed to different concentrations of Cr (VI) (LC(12.5), LC(25) and LC(50)) following 96h static renewal bioassay. The results of this study clearly show that the fish experienced OS as characterized by significant modulation of enzyme activities, induction of DNA damage and microscopic morphological changes in the liver and kidney. In both tissues, CAT activity was decreased whereas SOD activity and hydroperoxide levels were increased. In addition, GPx activity also increased significantly in higher test concentrations, especially in the kidney. MT induction and DNA damage were observed in both tissues in a concentration dependent manner. Microscopic examination of organ morphology indicated degeneration of liver tissue and necrosis of central vein. Necrosis of kidney tubular epithelial cells and tubules was observed at higher Cr (VI) concentrations. Taking together the findings of this study are helpful in organ-specific risk assessment of Cr (VI)-induced oxidative stress, genotoxicity and histopathology in fish."
1231554,Hu et al. 2010,Hexavalent chromium removal from near natural water by copper-iron bimetallic particles,"The reduction of hexavalent chromium (Cr(VI)) by zero-valent iron (ZVI) is self-inhibiting in near natural groundwater because insulating Fe(III)-Cr(III) (oxy)hydroxide film forms on the ZVI surface during the reaction. This study tries to overcome this deficiency by coating the surface of ZVI with copper to form copper-iron bimetallic particles. The Cr(VI) removal rate by ZVI rose significantly after the copper coating was applied. The copper loading needed for enhancing Cr(VI) removal was much higher than that needed for enhancing removal of chlorinated organic compounds or other oxidative contaminants, because of the higher oxidation potential of Cr(VI). The results of X-ray photoelectron spectroscopy (XPS) indicate that coating copper onto the surface of ZVI can not only increase the deepness of the oxidation film but also increase the oxidation state of iron in the film. This phenomenon means higher Cr(VI) removal capacity per unit weight of ZVI.","Hexavalent chromium removal from near natural water by copper-iron bimetallic particles Abs: The reduction of hexavalent chromium (Cr(VI)) by zero-valent iron (ZVI) is self-inhibiting in near natural groundwater because insulating Fe(III)-Cr(III) (oxy)hydroxide film forms on the ZVI surface during the reaction. This study tries to overcome this deficiency by coating the surface of ZVI with copper to form copper-iron bimetallic particles. The Cr(VI) removal rate by ZVI rose significantly after the copper coating was applied. The copper loading needed for enhancing Cr(VI) removal was much higher than that needed for enhancing removal of chlorinated organic compounds or other oxidative contaminants, because of the higher oxidation potential of Cr(VI). The results of X-ray photoelectron spectroscopy (XPS) indicate that coating copper onto the surface of ZVI can not only increase the deepness of the oxidation film but also increase the oxidation state of iron in the film. This phenomenon means higher Cr(VI) removal capacity per unit weight of ZVI."
1231553,Cleveland et al. 2009,Urate oxidase knockdown decreases oxidative stress in a murine hepatic cell line,"Humans, birds, and some primates do not express the uric acid degrading enzyme urate oxidase (UOX) and, as a result, have plasma uric acid concentrations higher than UOX expressing animals. Although high uric acid concentrations are suggested to increase the antioxidant defense system and provide a health advantage to animals without UOX, knockout mice lacking UOX develop pathological complications including gout and kidney failure. As an alternative to the knockout model, RNA interference was used to decrease UOX expression using stable transfection in a mouse hepatic cell line (ATCC, FL83B). Urate oxidase mRNA was reduced 66% (p &lt; 0.05) compared to wild type, as measured by real time RT-PCR. To determine if UOX knockdown resulted in enhanced protection against oxidative stress, cells were challenged with hexavalent chromium (Cr(VI)) or 3-morpholinosydnonimine hydrochloride (SIN-1). Compared to wild type, cells with UOX knockdown exhibited a 37.2 +/- 3.5% reduction (p &lt; 0.05) in the electron spin resonance (ESR) signal after being exposed to Cr(VI) and displayed less DNA fragmentation (p &lt; 0.05) following SIN-1 treatment. Cell viability decreased in wild type cells (p &lt; 0.05), but not cells with UOX knockdown, after treatment with SIN-1. These results are consistent with an increased intracellular uric acid concentration and an increased defense against oxidative stress.","Urate oxidase knockdown decreases oxidative stress in a murine hepatic cell line Abs: Humans, birds, and some primates do not express the uric acid degrading enzyme urate oxidase (UOX) and, as a result, have plasma uric acid concentrations higher than UOX expressing animals. Although high uric acid concentrations are suggested to increase the antioxidant defense system and provide a health advantage to animals without UOX, knockout mice lacking UOX develop pathological complications including gout and kidney failure. As an alternative to the knockout model, RNA interference was used to decrease UOX expression using stable transfection in a mouse hepatic cell line (ATCC, FL83B). Urate oxidase mRNA was reduced 66% (p &lt; 0.05) compared to wild type, as measured by real time RT-PCR. To determine if UOX knockdown resulted in enhanced protection against oxidative stress, cells were challenged with hexavalent chromium (Cr(VI)) or 3-morpholinosydnonimine hydrochloride (SIN-1). Compared to wild type, cells with UOX knockdown exhibited a 37.2 +/- 3.5% reduction (p &lt; 0.05) in the electron spin resonance (ESR) signal after being exposed to Cr(VI) and displayed less DNA fragmentation (p &lt; 0.05) following SIN-1 treatment. Cell viability decreased in wild type cells (p &lt; 0.05), but not cells with UOX knockdown, after treatment with SIN-1. These results are consistent with an increased intracellular uric acid concentration and an increased defense against oxidative stress."
1231550,Gatto et al. 2010,Occupational exposure to hexavalent chromium and cancers of the gastrointestinal tract: a meta-analysis,"<strong>INTRODUCTION: </strong>We conducted a systematic literature review and meta-analysis of oral cavity, esophageal, stomach, small intestine, colon, and rectal cancers among workers occupationally exposed to Cr(VI).<br /><br /><strong>METHODS: </strong>Using PubMed, studies published from 1950 to 2009 evaluating the relationship between Cr(VI) exposure and GI cancers were identified. Measures of effect and variability were extracted from 32 studies meeting specific inclusion criteria, and meta-analysis summary relative risk measures were calculated using random effects models and inverse variance weighting methods.<br /><br /><strong>RESULTS: </strong>Meta-standardized mortality ratios (SMRs) were, for cancer of the: oral cavity [1.02 (95% CI=0.77-1.34)]; esophagus [1.17 (95% CI=0.90-1.51)]; stomach [1.09 (95% CI=0.93-1.28)]; colon [0.89 (95% CI=0.70-1.12)]; and rectum [1.17 (95% CI=0.98-1.39)]. Analyses of more highly exposed subgroups included in the studies or subgroups based on geographic region or by industry with recognized Cr(VI) exposures (welding, chrome plating, chromate production, and pigment production) did not result in elevated meta-SMRs except for esophageal cancer among US cohorts [meta-SMR=1.49 (95% CI=1.06-2.09)]. However, that finding was based on a subgroup of only four studies, one of which was a PMR study. Potential confounding by socioeconomic status (SES), diet and/or smoking, or limitations due to the healthy-worker effect (HWE) were evaluated, and while smoking, diet and SES may be important factors that may have upwardly biased the meta-SMRs, HWE is not likely to have significantly affected the summary results. None of three studies reporting small intestine cancers observed a statistically significant increased risk.<br /><br /><strong>DISCUSSION: </strong>These meta-analyses and literature review indicate that Cr(VI)-exposed workers are not at a greater risk of GI cancers than the general population.","Occupational exposure to hexavalent chromium and cancers of the gastrointestinal tract: a meta-analysis Abs: <strong>INTRODUCTION: </strong>We conducted a systematic literature review and meta-analysis of oral cavity, esophageal, stomach, small intestine, colon, and rectal cancers among workers occupationally exposed to Cr(VI).<br /><br /><strong>METHODS: </strong>Using PubMed, studies published from 1950 to 2009 evaluating the relationship between Cr(VI) exposure and GI cancers were identified. Measures of effect and variability were extracted from 32 studies meeting specific inclusion criteria, and meta-analysis summary relative risk measures were calculated using random effects models and inverse variance weighting methods.<br /><br /><strong>RESULTS: </strong>Meta-standardized mortality ratios (SMRs) were, for cancer of the: oral cavity [1.02 (95% CI=0.77-1.34)]; esophagus [1.17 (95% CI=0.90-1.51)]; stomach [1.09 (95% CI=0.93-1.28)]; colon [0.89 (95% CI=0.70-1.12)]; and rectum [1.17 (95% CI=0.98-1.39)]. Analyses of more highly exposed subgroups included in the studies or subgroups based on geographic region or by industry with recognized Cr(VI) exposures (welding, chrome plating, chromate production, and pigment production) did not result in elevated meta-SMRs except for esophageal cancer among US cohorts [meta-SMR=1.49 (95% CI=1.06-2.09)]. However, that finding was based on a subgroup of only four studies, one of which was a PMR study. Potential confounding by socioeconomic status (SES), diet and/or smoking, or limitations due to the healthy-worker effect (HWE) were evaluated, and while smoking, diet and SES may be important factors that may have upwardly biased the meta-SMRs, HWE is not likely to have significantly affected the summary results. None of three studies reporting small intestine cancers observed a statistically significant increased risk.<br /><br /><strong>DISCUSSION: </strong>These meta-analyses and literature review indicate that Cr(VI)-exposed workers are not at a greater risk of GI cancers than the general population."
1231549,Marguí et al. 2010,Determination of water-soluble hexavalent chromium in clinker samples by wavelength-dispersive X-ray fluorescence spectrometry after concentration in activated layers,"The determination of hexavalent chromium (Cr(VI)) in cement-related material extracts is frequently monitored in cement industries to comply with the European Directive (2003/53/EC) that limits the use of cements containing more than 2 mg kg(-1) of water-soluble Cr(VI). In the present work, a rapid and simple method for the determination of water-soluble Cr(VI) in clinker samples has been developed. The analytical methodology is based on the combined use of a low cost Cr(VI) isolation procedure using activated layers followed by their analysis using wavelength-dispersive X-ray fluorescence (WDXRF) spectrometry. WDXRF instrumentation is a common tool used for determining the chemical composition of all materials involved in cement production and also for the quality control of the products produced in cement and concrete factories. Therefore, the presented methodology does not imply the use of additional instrumentation in cement-industries laboratories and can be used as a comparative method to the spectrophotometric reference (EN 196-10:2006). The analytical parameters evaluated (selectivity, limit of detection, linearity, and precision) prove to be suitable for the intended purpose, and the methodology has successfully been applied to determine water-soluble Cr(VI) in several clinker samples.","Determination of water-soluble hexavalent chromium in clinker samples by wavelength-dispersive X-ray fluorescence spectrometry after concentration in activated layers Abs: The determination of hexavalent chromium (Cr(VI)) in cement-related material extracts is frequently monitored in cement industries to comply with the European Directive (2003/53/EC) that limits the use of cements containing more than 2 mg kg(-1) of water-soluble Cr(VI). In the present work, a rapid and simple method for the determination of water-soluble Cr(VI) in clinker samples has been developed. The analytical methodology is based on the combined use of a low cost Cr(VI) isolation procedure using activated layers followed by their analysis using wavelength-dispersive X-ray fluorescence (WDXRF) spectrometry. WDXRF instrumentation is a common tool used for determining the chemical composition of all materials involved in cement production and also for the quality control of the products produced in cement and concrete factories. Therefore, the presented methodology does not imply the use of additional instrumentation in cement-industries laboratories and can be used as a comparative method to the spectrophotometric reference (EN 196-10:2006). The analytical parameters evaluated (selectivity, limit of detection, linearity, and precision) prove to be suitable for the intended purpose, and the methodology has successfully been applied to determine water-soluble Cr(VI) in several clinker samples."
1231548,Gnanamani et al. 2010,Microbial products (biosurfactant and extracellular chromate reductase) of marine microorganism are the potential agents reduce the oxidative stress induced by toxic heavy metals,"The present study demonstrates hexavalent chromium reduction and trivalent chromium tolerance behavior of marine Bacillus sp., MTCC 5514 through its extracellular enzyme reductase and biosurfactants production. The isolate reduces 10-2000 mg/L of hexavalent chromium to trivalent chromium with in 24-96 h respectively and the release of extracellular chromium reductase, found responsible for the reduction. Upon reduction, the concentration of trivalent chromium in the medium found comparatively less. Experimental results reveal, biosurfactants activity found responsible for the less concentration of Cr(III). Hypothetically, trivalent chromium upon formation get entrapped in the micelle of biosurfactants, prevents microbial cells from exposure towards trivalent chromium. Thus, the chosen isolate exhibit tolerance and growth with the increasing concentration of chromium.","Microbial products (biosurfactant and extracellular chromate reductase) of marine microorganism are the potential agents reduce the oxidative stress induced by toxic heavy metals Abs: The present study demonstrates hexavalent chromium reduction and trivalent chromium tolerance behavior of marine Bacillus sp., MTCC 5514 through its extracellular enzyme reductase and biosurfactants production. The isolate reduces 10-2000 mg/L of hexavalent chromium to trivalent chromium with in 24-96 h respectively and the release of extracellular chromium reductase, found responsible for the reduction. Upon reduction, the concentration of trivalent chromium in the medium found comparatively less. Experimental results reveal, biosurfactants activity found responsible for the less concentration of Cr(III). Hypothetically, trivalent chromium upon formation get entrapped in the micelle of biosurfactants, prevents microbial cells from exposure towards trivalent chromium. Thus, the chosen isolate exhibit tolerance and growth with the increasing concentration of chromium."
1231547,Liu et al. 2010,Effects of physicochemical factors on Cr(VI) removal from leachate by zero-valent iron and alpha-Fe(2)O(3) nanoparticles,"The effects of nanoparticle dosage, initial hexavalent chromium concentration, pH value, reaction temperature, and initial concentration of humic acid (HA) on chromate (CrO(4)(2-)) removal from landfill leachate by nanoscale zero-valent iron (NZVI) and hematite (alpha-Fe(2)O(3)) nanoparticles were examined in the present investigations. The Cr(VI) removal rate decreased as the initial Cr(VI) concentration and the reaction temperature increased, whereas corresponding removal rate by NZVI was higher than that of alpha-Fe(2)O(3). The optimum pH for the removal of Cr(VI) by NZVI was found to be 5.0 and more than 99.0% of Cr(VI) was removed within 5 h. However, the removal rate by alpha-Fe(2)O(3) decreased as pH increased. Presence of HA resulted in substantial reduction in the rate and extent of Cr(VI) removal by NZVI, whereas Cr(VI) removal rate by alpha-Fe(2)O(3) did not significantly decrease as HA concentration increased from 0.5 g/L to 3.0 g/L. Increasing the dosage of nanoparticles enhanced the rate constant and the removal of Cr(VI) by NZVI and alpha-Fe(2)O(3) followed pseudo-first-order reaction kinetics. The information should be very useful for the successful application of NZVI and alpha-Fe(2)O(3) for the treatment of groundwater or raw wastewater.","Effects of physicochemical factors on Cr(VI) removal from leachate by zero-valent iron and alpha-Fe(2)O(3) nanoparticles Abs: The effects of nanoparticle dosage, initial hexavalent chromium concentration, pH value, reaction temperature, and initial concentration of humic acid (HA) on chromate (CrO(4)(2-)) removal from landfill leachate by nanoscale zero-valent iron (NZVI) and hematite (alpha-Fe(2)O(3)) nanoparticles were examined in the present investigations. The Cr(VI) removal rate decreased as the initial Cr(VI) concentration and the reaction temperature increased, whereas corresponding removal rate by NZVI was higher than that of alpha-Fe(2)O(3). The optimum pH for the removal of Cr(VI) by NZVI was found to be 5.0 and more than 99.0% of Cr(VI) was removed within 5 h. However, the removal rate by alpha-Fe(2)O(3) decreased as pH increased. Presence of HA resulted in substantial reduction in the rate and extent of Cr(VI) removal by NZVI, whereas Cr(VI) removal rate by alpha-Fe(2)O(3) did not significantly decrease as HA concentration increased from 0.5 g/L to 3.0 g/L. Increasing the dosage of nanoparticles enhanced the rate constant and the removal of Cr(VI) by NZVI and alpha-Fe(2)O(3) followed pseudo-first-order reaction kinetics. The information should be very useful for the successful application of NZVI and alpha-Fe(2)O(3) for the treatment of groundwater or raw wastewater."
1231546,Wang et al. 2010,Reduction remediation of hexavalent chromium by bacterial flora in Cr(VI) aqueous solution,Chromium(VI) is a priority pollutant in soils and wastewaters and reduction of Cr(VI) to Cr(III) is a solution to this problem. In this study a low-cost method was proposed to adapt indigenous bacteria and use them to reduce Cr(VI) in solutions. The experiment results show that Cr(VI) could be efficiently reduced by indigenous bacteria under anaerobic and pH-unadjusted conditions. After about 24 h the concentration of Cr(VI) could be reduced from 21.74 mg/L to below 0.5 mg/L. The observed Cr(VI) reduction rates were affected by temperature and pH. Cr(VI) in aqueous solutions could be reduced to Cr(III) completely and partly be incepted by the organisms. Cr(VI) reduction was enzyme-mediated. It was not an energy-conserving process but a detoxification reaction. This method could be used in an anaerobic reactor to treat low-concentration wastewater or industrial water as the last step.,Reduction remediation of hexavalent chromium by bacterial flora in Cr(VI) aqueous solution Abs: Chromium(VI) is a priority pollutant in soils and wastewaters and reduction of Cr(VI) to Cr(III) is a solution to this problem. In this study a low-cost method was proposed to adapt indigenous bacteria and use them to reduce Cr(VI) in solutions. The experiment results show that Cr(VI) could be efficiently reduced by indigenous bacteria under anaerobic and pH-unadjusted conditions. After about 24 h the concentration of Cr(VI) could be reduced from 21.74 mg/L to below 0.5 mg/L. The observed Cr(VI) reduction rates were affected by temperature and pH. Cr(VI) in aqueous solutions could be reduced to Cr(III) completely and partly be incepted by the organisms. Cr(VI) reduction was enzyme-mediated. It was not an energy-conserving process but a detoxification reaction. This method could be used in an anaerobic reactor to treat low-concentration wastewater or industrial water as the last step.
1231545,Qureshi and  Mahmood 2010,Prospective role of ascorbic acid (vitamin C) in attenuating hexavalent chromium-induced functional and cellular damage in rat thyroid,"Occupational exposure to toxic heavy metals may render industrial workers with thyroid-related problems. Here, we examined the role of ascorbic acid (vitamin C) against hexavalent chromium Cr (VI)-induced damage in rat thyroid gland. Potassium dichromate (K2Cr2O7) and ascorbic acid doses were 60 microg and 120 mg kg(-1) body wt (intraperitoneally [i.p.]) respectively. Treatment regimens were group I rats, saline treated control; group II, only K2Cr2O7; group III, ascorbic acid 1 hour prior K2Cr2O7; group IV, simultaneous doses of ascorbic acid and K2Cr2O7, and group V, a combined premix dose of ascorbic acid and K2 Cr2O7 (2:1 ratio). Blood samples were taken before dosing the animals and 48 hours post exposure to determine the serum thyroid-stimulating hormone (TSH), free triiodothyronine (FT3) and free thyroxine (FT4) concentrations. Toward end of experiment, rats were sacrificed and thyroid glands were processed to evaluate the extent of cellular insult. Results showed significantly increased TSH and decreased FT3 and FT4 concentrations in groups II, III and IV rats as compared to control levels (p &lt; 0.05). In contrast, in group V rats, serum TSH, FT3 and FT4 concentrations neared control concentrations. Histopathologically, protective effect of ascorbic acid was found in group V rats only, where thyroid gland structure neared control thyroid except the follicular size that was decreased (p &lt; 0.05). Follicular density was no different from control. Basal laminae were intact, interfollicular spaces were normal. Colloid retraction and/or reabsorption were reduced maximally. Epithelial cell height was no different from control; epithelial follicular index increased only 1.3 fold, whereas nuclear-cytoplasmic (N/C) ratio was decreased by 14% only. The study indicates that the ascorbic acid may have the potential to protect thyroid gland from chromium toxicity; however, the study warrants further in-depth experimentation to precisely elucidate this role.","Prospective role of ascorbic acid (vitamin C) in attenuating hexavalent chromium-induced functional and cellular damage in rat thyroid Abs: Occupational exposure to toxic heavy metals may render industrial workers with thyroid-related problems. Here, we examined the role of ascorbic acid (vitamin C) against hexavalent chromium Cr (VI)-induced damage in rat thyroid gland. Potassium dichromate (K2Cr2O7) and ascorbic acid doses were 60 microg and 120 mg kg(-1) body wt (intraperitoneally [i.p.]) respectively. Treatment regimens were group I rats, saline treated control; group II, only K2Cr2O7; group III, ascorbic acid 1 hour prior K2Cr2O7; group IV, simultaneous doses of ascorbic acid and K2Cr2O7, and group V, a combined premix dose of ascorbic acid and K2 Cr2O7 (2:1 ratio). Blood samples were taken before dosing the animals and 48 hours post exposure to determine the serum thyroid-stimulating hormone (TSH), free triiodothyronine (FT3) and free thyroxine (FT4) concentrations. Toward end of experiment, rats were sacrificed and thyroid glands were processed to evaluate the extent of cellular insult. Results showed significantly increased TSH and decreased FT3 and FT4 concentrations in groups II, III and IV rats as compared to control levels (p &lt; 0.05). In contrast, in group V rats, serum TSH, FT3 and FT4 concentrations neared control concentrations. Histopathologically, protective effect of ascorbic acid was found in group V rats only, where thyroid gland structure neared control thyroid except the follicular size that was decreased (p &lt; 0.05). Follicular density was no different from control. Basal laminae were intact, interfollicular spaces were normal. Colloid retraction and/or reabsorption were reduced maximally. Epithelial cell height was no different from control; epithelial follicular index increased only 1.3 fold, whereas nuclear-cytoplasmic (N/C) ratio was decreased by 14% only. The study indicates that the ascorbic acid may have the potential to protect thyroid gland from chromium toxicity; however, the study warrants further in-depth experimentation to precisely elucidate this role."
1231544,Beauregard et al. 2010,Using non-invasive magnetic resonance imaging (MRI) to assess the reduction of Cr(VI) using a biofilm-palladium catalyst,"Industrial waste streams may contain contaminants that are valuable like Pd(II) and/or toxic and mutagenic like Cr(VI). Using Serratia sp. biofilm the former was biomineralized to produce a supported nanocrystalline Pd(0) catalyst, and this biofilm-Pd heterogeneous catalyst was then used to reduce Cr(VI) to less dangerous Cr(III) at room temperature, with formate as the electron donor. Cr(VI)((aq)) is non-paramagnetic while Cr(III)((aq)) is paramagnetic, which enabled spatial mapping of Cr species concentrations within the reactor cell using non-invasive magnetic resonance (MR) imaging experiments. Spatial reactivity heterogeneities were thus examined. In batch reactions, these could be attributed primarily to heterogeneity of Pd(0) distribution and to the development of gas bubbles within the reactor. In continuous flow reactions, spatial reactivity heterogeneities resulted primarily from heterogeneity of Cr(VI) delivery.","Using non-invasive magnetic resonance imaging (MRI) to assess the reduction of Cr(VI) using a biofilm-palladium catalyst Abs: Industrial waste streams may contain contaminants that are valuable like Pd(II) and/or toxic and mutagenic like Cr(VI). Using Serratia sp. biofilm the former was biomineralized to produce a supported nanocrystalline Pd(0) catalyst, and this biofilm-Pd heterogeneous catalyst was then used to reduce Cr(VI) to less dangerous Cr(III) at room temperature, with formate as the electron donor. Cr(VI)((aq)) is non-paramagnetic while Cr(III)((aq)) is paramagnetic, which enabled spatial mapping of Cr species concentrations within the reactor cell using non-invasive magnetic resonance (MR) imaging experiments. Spatial reactivity heterogeneities were thus examined. In batch reactions, these could be attributed primarily to heterogeneity of Pd(0) distribution and to the development of gas bubbles within the reactor. In continuous flow reactions, spatial reactivity heterogeneities resulted primarily from heterogeneity of Cr(VI) delivery."
1231543,Colica et al. 2010,Treatment of Cr(VI)-containing wastewaters with exopolysaccharide-producing cyanobacteria in pilot flow through and batch systems,"Seven exopolysaccharide-producing cyanobacteria were tested with regard to their capability to remove Cr(VI) from the wastewater of a plating industry. The cyanobacterium which showed, under lab conditions, the most promising features with regard to both Cr(VI) removal (about 12 mg of Cr(VI) removed per gram of dry biomass) and growth characteristics (highest growth rate and simplest culture medium) was Nostoc PCC7936. Furthermore, in lab experiments, it was also found that a HCl pretreatment is essential to abate the concentration of Cr(VI) in solution and that the viability of the biomass is not necessary. Subsequently, three pilot devices were tested, one batch (a dialysis cell) and two flow-through systems (a filter press and a column filled with quartz grain). The best performances were obtained with the filter press, where it was observed a sharp decrease in the concentration of Cr(VI), partly due to the adsorption of the metal by the biomass (about 50%) and partly due to its reduction to Cr(III). The results are discussed in terms of the role played by the different components (biomass and polysaccharide) of the cyanobacterial cultures in the removal of Cr(VI).","Treatment of Cr(VI)-containing wastewaters with exopolysaccharide-producing cyanobacteria in pilot flow through and batch systems Abs: Seven exopolysaccharide-producing cyanobacteria were tested with regard to their capability to remove Cr(VI) from the wastewater of a plating industry. The cyanobacterium which showed, under lab conditions, the most promising features with regard to both Cr(VI) removal (about 12 mg of Cr(VI) removed per gram of dry biomass) and growth characteristics (highest growth rate and simplest culture medium) was Nostoc PCC7936. Furthermore, in lab experiments, it was also found that a HCl pretreatment is essential to abate the concentration of Cr(VI) in solution and that the viability of the biomass is not necessary. Subsequently, three pilot devices were tested, one batch (a dialysis cell) and two flow-through systems (a filter press and a column filled with quartz grain). The best performances were obtained with the filter press, where it was observed a sharp decrease in the concentration of Cr(VI), partly due to the adsorption of the metal by the biomass (about 50%) and partly due to its reduction to Cr(III). The results are discussed in terms of the role played by the different components (biomass and polysaccharide) of the cyanobacterial cultures in the removal of Cr(VI)."
1231540,Kubrak et al. 2010,"Chromium effects on free radical processes in goldfish tissues: comparison of Cr(III) and Cr(VI) exposures on oxidative stress markers, glutathione status and antioxidant enzymes","The present study directly compared the effects of exposure to Cr6+ and Cr3+ (10 mg/L) over 24, 48 and 96 h on indices of oxidative stress and activities of antioxidant and related enzymes in goldfish brain, liver, kidney and gills. Glutathione status clearly demonstrated the development of oxidative stress, whereas changes in protein carbonyls and lipid peroxides were less pronounced. The activity of superoxide dismutase (SOD) was virtually unaffected after 24 or 96 h exposure, but 48 h exposure to Cr6+ reduced SOD activity in brain (by 30%), enhanced activity in kidney (by 28%) and had no effect on liver SOD. Chromium exposure for shorter times had no effect on catalase activity, whereas 96 h exposure depressed activity in liver, kidney and gills. Exposure to Cr6+ reduced catalase activity in liver by 53% and in kidney by 21%, while in gills it was reduced by 20 and 38% by exposure to Cr3+ and Cr6+, respectively. Exposure to chromium for 24 h did not affect glutathione-S-transferase activity, but treatment with Cr6+ for 48 h enhanced it in brain by 1.5-fold, whereas exposure to Cr3+ decreased activity by 29% in kidney. Fish treatment with chromium ions for 96 h decreased glutathione-S-transferase activity in liver by 51 and 25%, respectively. Chromium exposure had very little effect on the activities of GR or G6PDH. These data show that both chromium ions induced oxidative stress in goldfish tissues and affected the activity of antioxidant and associated enzymes.","Chromium effects on free radical processes in goldfish tissues: comparison of Cr(III) and Cr(VI) exposures on oxidative stress markers, glutathione status and antioxidant enzymes Abs: The present study directly compared the effects of exposure to Cr6+ and Cr3+ (10 mg/L) over 24, 48 and 96 h on indices of oxidative stress and activities of antioxidant and related enzymes in goldfish brain, liver, kidney and gills. Glutathione status clearly demonstrated the development of oxidative stress, whereas changes in protein carbonyls and lipid peroxides were less pronounced. The activity of superoxide dismutase (SOD) was virtually unaffected after 24 or 96 h exposure, but 48 h exposure to Cr6+ reduced SOD activity in brain (by 30%), enhanced activity in kidney (by 28%) and had no effect on liver SOD. Chromium exposure for shorter times had no effect on catalase activity, whereas 96 h exposure depressed activity in liver, kidney and gills. Exposure to Cr6+ reduced catalase activity in liver by 53% and in kidney by 21%, while in gills it was reduced by 20 and 38% by exposure to Cr3+ and Cr6+, respectively. Exposure to chromium for 24 h did not affect glutathione-S-transferase activity, but treatment with Cr6+ for 48 h enhanced it in brain by 1.5-fold, whereas exposure to Cr3+ decreased activity by 29% in kidney. Fish treatment with chromium ions for 96 h decreased glutathione-S-transferase activity in liver by 51 and 25%, respectively. Chromium exposure had very little effect on the activities of GR or G6PDH. These data show that both chromium ions induced oxidative stress in goldfish tissues and affected the activity of antioxidant and associated enzymes."
1231539,Velma and  Tchounwou 2011,"Hexavalent chromium-induced multiple biomarker responses in liver and kidney of goldfish, Carassius auratus","Hexavalent chromium [Cr (VI)] is a constituent of chromite ore. Although it is known to have several industrial and technological applications, its release into the aquatic environment as a result of chemical spill or inadequate waste discharge may hamper the health of aquatic organisms. In this study, we have investigated the effects of Cr (VI) on multiple biomarkers responses in goldfish under subchronic exposure conditions. Laboratory-acclimatized fish were exposed to 4.25 ppm and 8.57 ppm Cr (VI) for four weeks using a continuous flow-through system. During exposure, fish samples were collected on a weekly basis and analyzed for multiple biomarkers including catalase (CAT), superoxide dismutase (SOD), glutathione peroxidase (GPx), metallothionein (MT), and total protein in liver and kidney. Study results indicated that the CAT activity and total protein levels in Cr (VI) - treated goldfish did not significantly differ (P &gt; 0.05) from their respective controls during experimentation. However, highly significant up-regulations (P &lt; 0.05) of SOD, GPx, and MT expression in Cr (VI) - treated goldfish were recorded at different exposure times depending on Cr (VI) concentration, test organ, and/or biomarker of interest. For example, significantly higher liver GPx levels were found at weeks 2 and 3 in the 4.25 ppm concentration, and at weeks 3 and 4 in the 8.57 ppm, while kidney GPx levels were significantly higher at weeks 1, 2 and 3 in the 4.25 ppm concentration, and at weeks 2, 3 and 4 in the 8.57 ppm concentration. In summary, Cr (VI)-induced oxidative stress was characterized by statistically significant increases in SOD, GPx, and MT expression in goldfish tissues; with the kidney showing a relatively higher sensitivity to Cr (VI) toxicity compared with the liver.","Hexavalent chromium-induced multiple biomarker responses in liver and kidney of goldfish, Carassius auratus Abs: Hexavalent chromium [Cr (VI)] is a constituent of chromite ore. Although it is known to have several industrial and technological applications, its release into the aquatic environment as a result of chemical spill or inadequate waste discharge may hamper the health of aquatic organisms. In this study, we have investigated the effects of Cr (VI) on multiple biomarkers responses in goldfish under subchronic exposure conditions. Laboratory-acclimatized fish were exposed to 4.25 ppm and 8.57 ppm Cr (VI) for four weeks using a continuous flow-through system. During exposure, fish samples were collected on a weekly basis and analyzed for multiple biomarkers including catalase (CAT), superoxide dismutase (SOD), glutathione peroxidase (GPx), metallothionein (MT), and total protein in liver and kidney. Study results indicated that the CAT activity and total protein levels in Cr (VI) - treated goldfish did not significantly differ (P &gt; 0.05) from their respective controls during experimentation. However, highly significant up-regulations (P &lt; 0.05) of SOD, GPx, and MT expression in Cr (VI) - treated goldfish were recorded at different exposure times depending on Cr (VI) concentration, test organ, and/or biomarker of interest. For example, significantly higher liver GPx levels were found at weeks 2 and 3 in the 4.25 ppm concentration, and at weeks 3 and 4 in the 8.57 ppm, while kidney GPx levels were significantly higher at weeks 1, 2 and 3 in the 4.25 ppm concentration, and at weeks 2, 3 and 4 in the 8.57 ppm concentration. In summary, Cr (VI)-induced oxidative stress was characterized by statistically significant increases in SOD, GPx, and MT expression in goldfish tissues; with the kidney showing a relatively higher sensitivity to Cr (VI) toxicity compared with the liver."
1231538,Tekerlekopoulou et al. 2010,The effect of carbon source on microbial community structure and Cr(VI) reduction rate,"In the present work, the effect of the carbon source on microbial community structure in batch cultures derived from industrial sludge and hexavalent chromium reduction was studied. Experiments in aerobic batch reactors were carried out by amending industrial sludge with two different carbon sources: sodium acetate and sucrose. In each of the experiments performed, four different initial Cr(VI) concentrations of: 6, 13, 30 and 115 mg/L were tested. The change of carbon source in the batch reactor from sodium acetate to sucrose led to a 1.3-2.1 fold increase in chromium reduction rate and to a 5- to 9.5-fold increase in biomass. Analysis of the microbial structure in the batch reactor showed that the dominant communities were bacterial species (Acinetobacter lwoffii, Defluvibacter lusatiensis, Pseudoxanthomonas japonensis, Mesorhizium chacoense, and Flavobacterium suncheonense) when sodium acetate was used as carbon source and fungal strains (Trichoderma viride and Pichia jadinii), when sodium acetate was replaced by sucrose. These results indicate that the carbon source is a key parameter for microbial dynamics and enhanced chromium reduction and should be taken into account for efficient bioreactor design.","The effect of carbon source on microbial community structure and Cr(VI) reduction rate Abs: In the present work, the effect of the carbon source on microbial community structure in batch cultures derived from industrial sludge and hexavalent chromium reduction was studied. Experiments in aerobic batch reactors were carried out by amending industrial sludge with two different carbon sources: sodium acetate and sucrose. In each of the experiments performed, four different initial Cr(VI) concentrations of: 6, 13, 30 and 115 mg/L were tested. The change of carbon source in the batch reactor from sodium acetate to sucrose led to a 1.3-2.1 fold increase in chromium reduction rate and to a 5- to 9.5-fold increase in biomass. Analysis of the microbial structure in the batch reactor showed that the dominant communities were bacterial species (Acinetobacter lwoffii, Defluvibacter lusatiensis, Pseudoxanthomonas japonensis, Mesorhizium chacoense, and Flavobacterium suncheonense) when sodium acetate was used as carbon source and fungal strains (Trichoderma viride and Pichia jadinii), when sodium acetate was replaced by sucrose. These results indicate that the carbon source is a key parameter for microbial dynamics and enhanced chromium reduction and should be taken into account for efficient bioreactor design."
1231537,Zhang et al. 2010,Hexavalent chromium removal from aqueous solution by algal bloom residue derived activated carbon: equilibrium and kinetic studies,"A novel approach to prepare activated carbon from blue-green algal bloom residue has been tried for first time and its adsorption capability to remove hexavalent chromium Cr(VI) from aqueous solution has been examined. For this algal bloom residue derived activated carbon, the physical characters regarding adsorption capability were analyzed by scanning electron microscope (SEM), energy dispersive X-ray spectroscope (EDS) and Fourier transform infrared (FTIR) spectroscopy. Batch studies showed that initial pH, absorbent dosage, and initial concentration of Cr(VI) were important parameters for Cr(VI) absorption. It was found that initial pH of 1.0 was most favorable for Cr(VI) removal. The adsorption process followed the pseudo-second-order equation and Freundlich isotherm. The maximum adsorption capacity for Cr(VI) was 155.52 mg g(-1) in an acidic medium, which is comparable to best result from activated carbons derived from biomass. Therefore, this work put forward a nearly perfect solution which on one hand gets rid of environment-unfriendly algae residue while on the other hand produces high-quality activated carbon that is in return advantageous to environment protection.","Hexavalent chromium removal from aqueous solution by algal bloom residue derived activated carbon: equilibrium and kinetic studies Abs: A novel approach to prepare activated carbon from blue-green algal bloom residue has been tried for first time and its adsorption capability to remove hexavalent chromium Cr(VI) from aqueous solution has been examined. For this algal bloom residue derived activated carbon, the physical characters regarding adsorption capability were analyzed by scanning electron microscope (SEM), energy dispersive X-ray spectroscope (EDS) and Fourier transform infrared (FTIR) spectroscopy. Batch studies showed that initial pH, absorbent dosage, and initial concentration of Cr(VI) were important parameters for Cr(VI) absorption. It was found that initial pH of 1.0 was most favorable for Cr(VI) removal. The adsorption process followed the pseudo-second-order equation and Freundlich isotherm. The maximum adsorption capacity for Cr(VI) was 155.52 mg g(-1) in an acidic medium, which is comparable to best result from activated carbons derived from biomass. Therefore, this work put forward a nearly perfect solution which on one hand gets rid of environment-unfriendly algae residue while on the other hand produces high-quality activated carbon that is in return advantageous to environment protection."
1231536,Priyantha and  Bandaranayaka 2011,Interaction of Cr(VI) species with thermally treated brick clay,"<strong>PURPOSE: </strong>The purpose of this research is to investigate the interaction of Cr(VI) species, present as Cr?O?²?, at ambient temperature with brick clay pre-fired at different temperatures.<br /><br /><strong>METHODS: </strong>A multi-technique approach was used for this investigation. Experiments such as surface titrations, Langmuir and Freundlich adsorption isotherms, mass-firing temperature investigation, scanning electron microscopy, Fourier transform infrared spectra, X-ray fluorescence spectra, and X-ray diffraction were conducted in this investigation.<br /><br /><strong>RESULTS: </strong>Fired brick clay, which bears a negative charge according to surface titration measurements, shows affinity towards Cr(VI) species despite the negative charge of the source of Cr(VI). The Cr(VI)-brick clay heterogeneous system, which shows the strongest interaction with brick clay fired at 200 °C, obeys both the Langmuir and the Freundlich adsorption isotherms with high regression coefficients. Investigation on surface charge, constituents of brick clay, acid treatment of clay particles, and the effect of firing temperature suggests that the reduction of Cr(VI) to Cr(III) by reducing agents present in brick clay makes a significant contribution for adsorption of chromium species followed by subsequent removal. Scanning electron microscopic images support the adsorption of chromium species, and further, many metal ions are released as a result of Cr(VI)-brick clay interaction according to X-ray fluorescence studies.<br /><br /><strong>CONCLUSION: </strong>It is concluded that fired brick clay shows strong adsorption capacity on Cr(VI), having the maximum interaction with brick clay fired at 200 °C. It is proposed that this methodology be extended for treatment of effluents containing Cr(VI) species.","Interaction of Cr(VI) species with thermally treated brick clay Abs: <strong>PURPOSE: </strong>The purpose of this research is to investigate the interaction of Cr(VI) species, present as Cr?O?²?, at ambient temperature with brick clay pre-fired at different temperatures.<br /><br /><strong>METHODS: </strong>A multi-technique approach was used for this investigation. Experiments such as surface titrations, Langmuir and Freundlich adsorption isotherms, mass-firing temperature investigation, scanning electron microscopy, Fourier transform infrared spectra, X-ray fluorescence spectra, and X-ray diffraction were conducted in this investigation.<br /><br /><strong>RESULTS: </strong>Fired brick clay, which bears a negative charge according to surface titration measurements, shows affinity towards Cr(VI) species despite the negative charge of the source of Cr(VI). The Cr(VI)-brick clay heterogeneous system, which shows the strongest interaction with brick clay fired at 200 °C, obeys both the Langmuir and the Freundlich adsorption isotherms with high regression coefficients. Investigation on surface charge, constituents of brick clay, acid treatment of clay particles, and the effect of firing temperature suggests that the reduction of Cr(VI) to Cr(III) by reducing agents present in brick clay makes a significant contribution for adsorption of chromium species followed by subsequent removal. Scanning electron microscopic images support the adsorption of chromium species, and further, many metal ions are released as a result of Cr(VI)-brick clay interaction according to X-ray fluorescence studies.<br /><br /><strong>CONCLUSION: </strong>It is concluded that fired brick clay shows strong adsorption capacity on Cr(VI), having the maximum interaction with brick clay fired at 200 °C. It is proposed that this methodology be extended for treatment of effluents containing Cr(VI) species."
1231535,Bigorgne et al. 2010,"Genotoxic effects of nickel, trivalent and hexavalent chromium on the Eisenia fetida earthworm","The aim of this study was to examine genotoxic effects of nickel (Ni=105 mg kg(-1)), trivalent and hexavalent chromium (Cr=491 mg kg(-1)) on the Eisenia fetida earthworm after 2 and 4d of exposure to two different spiked soils (an artificial (OECD) and a natural one). DNA damages were evaluated on the earthworm's coelomocytes using the comet assay. After an exposure into OECD spiked soils, Ni did not induce genotoxic effect whereas Cr(III) and Cr(VI) revealed to be genotoxic after 2d of exposure. After 4d of exposure, only Cr(VI) still induced significant damages. In natural spiked soils, nickel and Cr(III) revealed to be genotoxic after 2 and 4d of exposure. Concerning Cr(VI) toxicity, all the earthworms died after 1d of exposure. These results underline the importance to take into account the nature and the speciation of metallic pollutants, although the experiment has been performed on spiked soil with higher bioavailibity than in contaminated natural soil.","Genotoxic effects of nickel, trivalent and hexavalent chromium on the Eisenia fetida earthworm Abs: The aim of this study was to examine genotoxic effects of nickel (Ni=105 mg kg(-1)), trivalent and hexavalent chromium (Cr=491 mg kg(-1)) on the Eisenia fetida earthworm after 2 and 4d of exposure to two different spiked soils (an artificial (OECD) and a natural one). DNA damages were evaluated on the earthworm's coelomocytes using the comet assay. After an exposure into OECD spiked soils, Ni did not induce genotoxic effect whereas Cr(III) and Cr(VI) revealed to be genotoxic after 2d of exposure. After 4d of exposure, only Cr(VI) still induced significant damages. In natural spiked soils, nickel and Cr(III) revealed to be genotoxic after 2 and 4d of exposure. Concerning Cr(VI) toxicity, all the earthworms died after 1d of exposure. These results underline the importance to take into account the nature and the speciation of metallic pollutants, although the experiment has been performed on spiked soil with higher bioavailibity than in contaminated natural soil."
1231530,Sarkar et al. 2010,Remediation of hexavalent chromium through adsorption by bentonite based Arquad® 2HT-75 organoclays,"Unlike hydrophobic organic pollutants, the potential of organoclays to adsorb inorganic ionic contaminants is relatively underexplored. The present study attempts to characterise bentonite (QB) based organoclays synthesised from a commercially available, low-cost alkyl ammonium surfactant Arquad® 2HT-75 (Aq) and test their ability to adsorb hexavalent chromium (Cr (VI)) in aqueous solution. XRD, FTIR and TGA characterisation techniques prove successful modification of the bentonite structure and reveal that higher surfactant loadings gives rise to more ordered surfactant conformation in the organoclays. The zeta potential values indicate that higher surfactant loadings also create positive charges on the organoclay surfaces. Detailed isothermal and kinetic studies show that the organoclays effectively remove hexavalent chromium (Cr (VI)) from aqueous solution by both physical and chemical adsorption processes. Higher surfactant loadings provide better adsorption efficiency. The adsorption performance is reasonably efficient under the levels of pH, temperature, electrolyte concentration and natural organic matter concentration that generally prevail in contaminated soil and water. This study shows that organoclay sorbents offer good potential for remediating Cr (VI) under real environmental conditions.","Remediation of hexavalent chromium through adsorption by bentonite based Arquad® 2HT-75 organoclays Abs: Unlike hydrophobic organic pollutants, the potential of organoclays to adsorb inorganic ionic contaminants is relatively underexplored. The present study attempts to characterise bentonite (QB) based organoclays synthesised from a commercially available, low-cost alkyl ammonium surfactant Arquad® 2HT-75 (Aq) and test their ability to adsorb hexavalent chromium (Cr (VI)) in aqueous solution. XRD, FTIR and TGA characterisation techniques prove successful modification of the bentonite structure and reveal that higher surfactant loadings gives rise to more ordered surfactant conformation in the organoclays. The zeta potential values indicate that higher surfactant loadings also create positive charges on the organoclay surfaces. Detailed isothermal and kinetic studies show that the organoclays effectively remove hexavalent chromium (Cr (VI)) from aqueous solution by both physical and chemical adsorption processes. Higher surfactant loadings provide better adsorption efficiency. The adsorption performance is reasonably efficient under the levels of pH, temperature, electrolyte concentration and natural organic matter concentration that generally prevail in contaminated soil and water. This study shows that organoclay sorbents offer good potential for remediating Cr (VI) under real environmental conditions."
1231529,Stern et al. 2010,Hexavalent chromium in house dust--a comparison between an area with historic contamination from chromate production and background locations,"In contrast to Cr(+3), Cr(+6) is carcinogenic and allergenic. Although Cr(+6) can occur naturally, it is thought that most soil Cr(+6) is anthropogenic, however, the extent of Cr(+6) in the background environment is unknown. Cr(+6)-containing chromite ore processing residue (COPR) from chromate manufacture was deposited in numerous locations in Jersey City (JC), New Jersey. In the 1990's, significantly elevated concentrations of total Cr (Cr(+6)+Cr(+3)) were found in house dust near COPR sites. We undertook a follow-up study to determine ongoing COPR exposure. We compared Cr(+6) in house dust in JC to selected background communities with no known sources of Cr(+6). Samples were collected from living areas, basements and window wells. Cr(+6) was detected in dust from all JC and background houses. In the JC homes, the mean (+ or - SD) Cr(+6) concentration for all samples was 3.9 + or - 7.0 microg/g (range: non-detect-90.4 microg/g), and the mean Cr(+6) loading was 5.8 + or - 15.7 microg/m(2) (range: non-detect-196.4 microg/m(2)). In background homes, the mean Cr(+6) concentrations of all samples was 4.6 + or - 7.8 microg/g, (range, 0.05-56.6 microg/g). The mean loading was 10.0 + or - 27.9 microg/m(2) (range, 0.22-169.3 microg/m(2)). There was no significant difference between Cr(+6) dust concentrations in Jersey City and background locations. Stratification by sample location within houses and sampling method gave similar results. Samples exceeding 20 microg/g were obtained only from single wood surfaces in different homes. Lower concentrations in window well samples suggests transport from outside is not the major source of indoor Cr(+6). Landscaping and groundcover may influence indoor Cr(+6). There appears to be a widespread low level background of Cr(+6) that is not elevated in Jersey City homes despite its historic COPR contamination. It is possible that house dust, in general, is a source of Cr(+6) exposure with potential implications for persistence of chromium allergic contact dermatitis.","Hexavalent chromium in house dust--a comparison between an area with historic contamination from chromate production and background locations Abs: In contrast to Cr(+3), Cr(+6) is carcinogenic and allergenic. Although Cr(+6) can occur naturally, it is thought that most soil Cr(+6) is anthropogenic, however, the extent of Cr(+6) in the background environment is unknown. Cr(+6)-containing chromite ore processing residue (COPR) from chromate manufacture was deposited in numerous locations in Jersey City (JC), New Jersey. In the 1990's, significantly elevated concentrations of total Cr (Cr(+6)+Cr(+3)) were found in house dust near COPR sites. We undertook a follow-up study to determine ongoing COPR exposure. We compared Cr(+6) in house dust in JC to selected background communities with no known sources of Cr(+6). Samples were collected from living areas, basements and window wells. Cr(+6) was detected in dust from all JC and background houses. In the JC homes, the mean (+ or - SD) Cr(+6) concentration for all samples was 3.9 + or - 7.0 microg/g (range: non-detect-90.4 microg/g), and the mean Cr(+6) loading was 5.8 + or - 15.7 microg/m(2) (range: non-detect-196.4 microg/m(2)). In background homes, the mean Cr(+6) concentrations of all samples was 4.6 + or - 7.8 microg/g, (range, 0.05-56.6 microg/g). The mean loading was 10.0 + or - 27.9 microg/m(2) (range, 0.22-169.3 microg/m(2)). There was no significant difference between Cr(+6) dust concentrations in Jersey City and background locations. Stratification by sample location within houses and sampling method gave similar results. Samples exceeding 20 microg/g were obtained only from single wood surfaces in different homes. Lower concentrations in window well samples suggests transport from outside is not the major source of indoor Cr(+6). Landscaping and groundcover may influence indoor Cr(+6). There appears to be a widespread low level background of Cr(+6) that is not elevated in Jersey City homes despite its historic COPR contamination. It is possible that house dust, in general, is a source of Cr(+6) exposure with potential implications for persistence of chromium allergic contact dermatitis."
1231527,Mauricio Gutiérrez et al. 2010,Isolation and characterization of hexavalent chromium-reducing rhizospheric bacteria from a wetland,"Scirpus americanus Pers. occurs naturally in &quot;San Germán,&quot; a pond that serves as a receptor of industrial wastewater in Guanajuato, México. This plant accumulates metals mainly in the root: concentrations (mg/kg) of Cr, As, Cd and Se were 970, 49, 41, and 85 respectively. Analysis of rhizosphere samples indicated bacterial population of 10(8) cfu g(-1) in media with 0.2 mM Cr(VI) and 10 mM sodium gluconate. Thirteen isolates were obtained and phylogenetic analyses (16S rRNA) indicated they corresponded to genera of Agrobacterium, Arthrobacter, Microbacterium, Curtobacterium, Rhodococcus, Xanthomonas and Pseudomonas. Cr(VI) reduction was evaluated using the diphenyl carbazide method. The isolates accomplished 5-40% (20 microM) of reduction in assays of resting cell and tolerated 0.5-5.0 mM Cr(VI). Eight strains used nitrate and thirteen used iron and chromium as electron acceptors to grow under anaerobic conditions. Cr(VI) reduction by five strains occurred at pH values (7-9) and NaCl concentrations (0.5-1.0 M) in basal medium. A mixed culture of strains (S17 and S28) reached a chromium removal of 100% at 0.2 mM Cr(VI) initial concentration. Aerobically, this consortium was capable of 93.8% Cr(VI) reduction of 81 microg L(-1) Cr(VI) of the industrial effluent, indicating their possible use in environmental cleanup.","Isolation and characterization of hexavalent chromium-reducing rhizospheric bacteria from a wetland Abs: Scirpus americanus Pers. occurs naturally in &quot;San Germán,&quot; a pond that serves as a receptor of industrial wastewater in Guanajuato, México. This plant accumulates metals mainly in the root: concentrations (mg/kg) of Cr, As, Cd and Se were 970, 49, 41, and 85 respectively. Analysis of rhizosphere samples indicated bacterial population of 10(8) cfu g(-1) in media with 0.2 mM Cr(VI) and 10 mM sodium gluconate. Thirteen isolates were obtained and phylogenetic analyses (16S rRNA) indicated they corresponded to genera of Agrobacterium, Arthrobacter, Microbacterium, Curtobacterium, Rhodococcus, Xanthomonas and Pseudomonas. Cr(VI) reduction was evaluated using the diphenyl carbazide method. The isolates accomplished 5-40% (20 microM) of reduction in assays of resting cell and tolerated 0.5-5.0 mM Cr(VI). Eight strains used nitrate and thirteen used iron and chromium as electron acceptors to grow under anaerobic conditions. Cr(VI) reduction by five strains occurred at pH values (7-9) and NaCl concentrations (0.5-1.0 M) in basal medium. A mixed culture of strains (S17 and S28) reached a chromium removal of 100% at 0.2 mM Cr(VI) initial concentration. Aerobically, this consortium was capable of 93.8% Cr(VI) reduction of 81 microg L(-1) Cr(VI) of the industrial effluent, indicating their possible use in environmental cleanup."
1231526,Jain et al. 2011,Investigation of Cr(VI) adsorption onto chemically treated Helianthus annuus: optimization using response surface methodology,"In the present study, chemically treated Helianthus annuus flowers (SHC) were used to optimize the removal efficiency for Cr(VI) by applying Response Surface Methodological approach. The surface structure of SHC was analyzed by Scanning Electron Microscopy (SEM) coupled with Energy Dispersive X-ray Analysis (EDX). Batch mode experiments were also carried out to assess the adsorption equilibrium in aqueous solution. The adsorption capacity (qe) was found to be 7.2 mg/g. The effect of three parameters, that is pH of the solution (2.0-7.0), initial concentration (10-70 mg/L) and adsorbent dose (0.05-0.5 g/100 mL) was studied for the removal of Cr(VI) by SHC. Box-Behnken model was used as an experimental design. The optimum pH, adsorbent dose and initial Cr(VI) concentration were found to be 2.0, 5.0 g/L and 40 mg/L, respectively. Under these conditions, removal efficiency of Cr(VI) was found to be 90.8%.","Investigation of Cr(VI) adsorption onto chemically treated Helianthus annuus: optimization using response surface methodology Abs: In the present study, chemically treated Helianthus annuus flowers (SHC) were used to optimize the removal efficiency for Cr(VI) by applying Response Surface Methodological approach. The surface structure of SHC was analyzed by Scanning Electron Microscopy (SEM) coupled with Energy Dispersive X-ray Analysis (EDX). Batch mode experiments were also carried out to assess the adsorption equilibrium in aqueous solution. The adsorption capacity (qe) was found to be 7.2 mg/g. The effect of three parameters, that is pH of the solution (2.0-7.0), initial concentration (10-70 mg/L) and adsorbent dose (0.05-0.5 g/100 mL) was studied for the removal of Cr(VI) by SHC. Box-Behnken model was used as an experimental design. The optimum pH, adsorbent dose and initial Cr(VI) concentration were found to be 2.0, 5.0 g/L and 40 mg/L, respectively. Under these conditions, removal efficiency of Cr(VI) was found to be 90.8%."
1231525,Driscoll et al. 2010,"Evaluation of hexavalent chromium in sediment pore water of the Hackensack River, New Jersey, USA","Pore water was collected from in situ passive samplers in Hackensack River sediments adjacent to a chromite ore processing residue site in Kearny, New Jersey. Although the sediments at this site contained more than 3,000 mg/kg of total chromium (Cr) and shallow groundwater adjacent to the shore contained more than 1,000 microg/L of hexavalent Cr [Cr(VI)], concentrations of dissolved total Cr and Cr(VI) in pore water (PW) samples were less than ambient water quality criteria for Cr(VI) (50 microg/L). Concentrations of dissolved total Cr in pore water ranged from &lt;2.0 to 5.3 microg/L, while Cr(VI) was not detected (&lt;10 microg/L). These findings are consistent with previous studies, which demonstrated limited bioavailability and toxicity of Cr in sediment at this site and others with similar conditions.","Evaluation of hexavalent chromium in sediment pore water of the Hackensack River, New Jersey, USA Abs: Pore water was collected from in situ passive samplers in Hackensack River sediments adjacent to a chromite ore processing residue site in Kearny, New Jersey. Although the sediments at this site contained more than 3,000 mg/kg of total chromium (Cr) and shallow groundwater adjacent to the shore contained more than 1,000 microg/L of hexavalent Cr [Cr(VI)], concentrations of dissolved total Cr and Cr(VI) in pore water (PW) samples were less than ambient water quality criteria for Cr(VI) (50 microg/L). Concentrations of dissolved total Cr in pore water ranged from &lt;2.0 to 5.3 microg/L, while Cr(VI) was not detected (&lt;10 microg/L). These findings are consistent with previous studies, which demonstrated limited bioavailability and toxicity of Cr in sediment at this site and others with similar conditions."
1231524,Stern 2010,A quantitative assessment of the carcinogenicity of hexavalent chromium by the oral route and its relevance to human exposure,"<strong>BACKGROUND: </strong>Hexavalent chromium (Cr(6+)) has long been recognized as an inhalation carcinogen. Useful data on its carcinogenicity by ingestion have been slower to develop. The 2008 NTP chronic bioassay of sodium dichromate dihydrate in drinking water found clear evidence of carcinogenicity in rodents and allows a generalizable estimate of the human ingestion cancer potency of Cr(6+).<br /><br /><strong>OBJECTIVES: </strong>To estimate the human ingestion cancer potency of Cr(6+) and evaluate its relevance for human exposure.<br /><br /><strong>METHODS: </strong>Tumors of the small intestine in male mice were selected as the critical endpoint, for the derivation of cancer potency. Following the 2005 USEPA Cancer Risk Assessment Guidelines, the point of departure in the dose-response data was defined using benchmark-dose modeling. Linear extrapolation was carried out from the point of departure and interspecies dose conversion was based on allometric scaling of body weight.<br /><br /><strong>RESULTS: </strong>Small intestine tumor incidence in male mice provided a robust and nearly identical fit with most available dose-response models using benchmark-dose modeling. A human equivalent cancer slope factor of 0.5 (mg/kg/day)(-1) was derived based on linear extrapolation from the point of departure. Statistical and kinetic analysis carried out on the NTP data as well as data reported in other studies support that the carcinogenicity of Cr(6+) did not result from an exceedance of the reduction capacity of the mouse gastrointestinal tract at the doses in the NTP study.<br /><br /><strong>CONCLUSIONS: </strong>Mouse gastric emptying time and human Cr(6+) dosing studies strongly suggest that even at doses considerably lower than those in the NTP study, Cr(6+) escapes reduction in both the mouse and human stomachs due to kinetic competition from Cr(6+) absorption and gastric emptying. The cancer potency derived from the NTP data is, therefore, deemed to be relevant and applicable to human exposure. Cr(6+) is, therefore, identified as &quot;likely to be carcinogenic to humans&quot; in accordance with the USEPA's cancer characterization rubric.","A quantitative assessment of the carcinogenicity of hexavalent chromium by the oral route and its relevance to human exposure Abs: <strong>BACKGROUND: </strong>Hexavalent chromium (Cr(6+)) has long been recognized as an inhalation carcinogen. Useful data on its carcinogenicity by ingestion have been slower to develop. The 2008 NTP chronic bioassay of sodium dichromate dihydrate in drinking water found clear evidence of carcinogenicity in rodents and allows a generalizable estimate of the human ingestion cancer potency of Cr(6+).<br /><br /><strong>OBJECTIVES: </strong>To estimate the human ingestion cancer potency of Cr(6+) and evaluate its relevance for human exposure.<br /><br /><strong>METHODS: </strong>Tumors of the small intestine in male mice were selected as the critical endpoint, for the derivation of cancer potency. Following the 2005 USEPA Cancer Risk Assessment Guidelines, the point of departure in the dose-response data was defined using benchmark-dose modeling. Linear extrapolation was carried out from the point of departure and interspecies dose conversion was based on allometric scaling of body weight.<br /><br /><strong>RESULTS: </strong>Small intestine tumor incidence in male mice provided a robust and nearly identical fit with most available dose-response models using benchmark-dose modeling. A human equivalent cancer slope factor of 0.5 (mg/kg/day)(-1) was derived based on linear extrapolation from the point of departure. Statistical and kinetic analysis carried out on the NTP data as well as data reported in other studies support that the carcinogenicity of Cr(6+) did not result from an exceedance of the reduction capacity of the mouse gastrointestinal tract at the doses in the NTP study.<br /><br /><strong>CONCLUSIONS: </strong>Mouse gastric emptying time and human Cr(6+) dosing studies strongly suggest that even at doses considerably lower than those in the NTP study, Cr(6+) escapes reduction in both the mouse and human stomachs due to kinetic competition from Cr(6+) absorption and gastric emptying. The cancer potency derived from the NTP data is, therefore, deemed to be relevant and applicable to human exposure. Cr(6+) is, therefore, identified as &quot;likely to be carcinogenic to humans&quot; in accordance with the USEPA's cancer characterization rubric."
1231523,Meeker et al. 2010,Hexavalent chromium exposure and control in welding tasks,"Studies of exposure to the lung carcinogen hexavalent chromium (CrVI) from welding tasks are limited, especially within the construction industry where overexposure may be common. In addition, despite the OSHA requirement that the use of engineering controls such as local exhaust ventilation (LEV) first be considered before relying on other strategies to reduce worker exposure to CrVI, data on the effectiveness of LEV to reduce CrVI exposures from welding are lacking. The goal of the present study was to characterize breathing zone air concentrations of CrVI during welding tasks and primary contributing factors in four datasets: (1) OSHA compliance data; (2) a publicly available database from The Welding Institute (TWI); (3) field survey data of construction welders collected by the Center for Construction Research and Training (CPWR); and (4) controlled welding trials conducted by CPWR to assess the effectiveness of a portable LEV unit to reduce CrVI exposure. In the OSHA (n = 181) and TWI (n = 124) datasets, which included very few samples from the construction industry, the OSHA permissible exposure level (PEL) for CrVI (5 ?g/m(3)) was exceeded in 9% and 13% of samples, respectively. CrVI concentrations measured in the CPWR field surveys (n = 43) were considerably higher, and 25% of samples exceeded the PEL. In the TWI and CPWR datasets, base metal, welding process, and LEV use were important predictors of CrVI concentrations. Only weak-to-moderate correlations were found between total particulate matter and CrVI, suggesting that total particulate matter concentrations are not a good surrogate for CrVI exposure in retrospective studies. Finally, in the controlled welding trials, LEV reduced median CrVI concentrations by 68% (p = 0.02). In conclusion, overexposure to CrVI in stainless steel welding is likely widespread, especially in certain operations such as shielded metal arc welding, which is commonly used in construction. However, exposure could be substantially reduced with proper use of LEV.","Hexavalent chromium exposure and control in welding tasks Abs: Studies of exposure to the lung carcinogen hexavalent chromium (CrVI) from welding tasks are limited, especially within the construction industry where overexposure may be common. In addition, despite the OSHA requirement that the use of engineering controls such as local exhaust ventilation (LEV) first be considered before relying on other strategies to reduce worker exposure to CrVI, data on the effectiveness of LEV to reduce CrVI exposures from welding are lacking. The goal of the present study was to characterize breathing zone air concentrations of CrVI during welding tasks and primary contributing factors in four datasets: (1) OSHA compliance data; (2) a publicly available database from The Welding Institute (TWI); (3) field survey data of construction welders collected by the Center for Construction Research and Training (CPWR); and (4) controlled welding trials conducted by CPWR to assess the effectiveness of a portable LEV unit to reduce CrVI exposure. In the OSHA (n = 181) and TWI (n = 124) datasets, which included very few samples from the construction industry, the OSHA permissible exposure level (PEL) for CrVI (5 ?g/m(3)) was exceeded in 9% and 13% of samples, respectively. CrVI concentrations measured in the CPWR field surveys (n = 43) were considerably higher, and 25% of samples exceeded the PEL. In the TWI and CPWR datasets, base metal, welding process, and LEV use were important predictors of CrVI concentrations. Only weak-to-moderate correlations were found between total particulate matter and CrVI, suggesting that total particulate matter concentrations are not a good surrogate for CrVI exposure in retrospective studies. Finally, in the controlled welding trials, LEV reduced median CrVI concentrations by 68% (p = 0.02). In conclusion, overexposure to CrVI in stainless steel welding is likely widespread, especially in certain operations such as shielded metal arc welding, which is commonly used in construction. However, exposure could be substantially reduced with proper use of LEV."
1231521,Jasso-Chávez et al. 2010,Toxic effects of Cr(VI) and Cr(III) on energy metabolism of heterotrophic Euglena gracilis,"To assess the toxic effect of Cr on energy metabolism, heterotrophic Euglena gracilis was grown in a medium that prompts high yield biomass and in the presence of different Cr(VI) or Cr(III) concentrations. The cell growth IC?? value was 12 and &gt;250?M for Cr(VI) and Cr(III), respectively; in these cells chromium was accumulated and a fraction compartmentalized into mitochondria, and synthesis of cysteine and glutathione was induced. Respiration of control isolated mitochondria was strongly inhibited by added Cr(VI) or Cr(III) with L-lactate or succinate as substrates. In turn, cellular and mitochondrial respiration, respiratory Complexes I, III and IV, glycolysis and cytosolic NAD(+)-alcohol and -lactate dehydrogenases from cells cultured with Cr(VI) were significantly lower than control, whereas AOX and external NADH dehydrogenase activities were unaltered or increased, respectively. Addition of Cr(VI) or Cr(III) to isolated mitochondria or cytosol from control- or Cr(VI)-grown cells induced inhibition of respiration, respiratory Complexes III, IV and AOX, and glycolytic pyruvate kinase; whereas Complex I, external NADH dehydrogenase, and other glycolytic enzymes were unaffected. Protein contents of mitochondrial Complexes I, III, IV and V, and ANT were diminished in Cr(VI)-grown cells. Decreased respiration and glycolysis induced by Cr(VI) resulted in lower cellular ATP content. Results suggested that Cr(VI) cytotoxicity altered gene expression (as widely documented) and hence enzyme content, and induced oxidative stress, but it was also related with direct enzyme inhibition; Cr(III) was also cytotoxic although at higher concentrations. These findings establish new paradigms for chromium toxicity: Cr(VI) direct enzyme inhibition and non-innocuous external Cr(III) toxicity.","Toxic effects of Cr(VI) and Cr(III) on energy metabolism of heterotrophic Euglena gracilis Abs: To assess the toxic effect of Cr on energy metabolism, heterotrophic Euglena gracilis was grown in a medium that prompts high yield biomass and in the presence of different Cr(VI) or Cr(III) concentrations. The cell growth IC?? value was 12 and &gt;250?M for Cr(VI) and Cr(III), respectively; in these cells chromium was accumulated and a fraction compartmentalized into mitochondria, and synthesis of cysteine and glutathione was induced. Respiration of control isolated mitochondria was strongly inhibited by added Cr(VI) or Cr(III) with L-lactate or succinate as substrates. In turn, cellular and mitochondrial respiration, respiratory Complexes I, III and IV, glycolysis and cytosolic NAD(+)-alcohol and -lactate dehydrogenases from cells cultured with Cr(VI) were significantly lower than control, whereas AOX and external NADH dehydrogenase activities were unaltered or increased, respectively. Addition of Cr(VI) or Cr(III) to isolated mitochondria or cytosol from control- or Cr(VI)-grown cells induced inhibition of respiration, respiratory Complexes III, IV and AOX, and glycolytic pyruvate kinase; whereas Complex I, external NADH dehydrogenase, and other glycolytic enzymes were unaffected. Protein contents of mitochondrial Complexes I, III, IV and V, and ANT were diminished in Cr(VI)-grown cells. Decreased respiration and glycolysis induced by Cr(VI) resulted in lower cellular ATP content. Results suggested that Cr(VI) cytotoxicity altered gene expression (as widely documented) and hence enzyme content, and induced oxidative stress, but it was also related with direct enzyme inhibition; Cr(III) was also cytotoxic although at higher concentrations. These findings establish new paradigms for chromium toxicity: Cr(VI) direct enzyme inhibition and non-innocuous external Cr(III) toxicity."
1231520,Piñón-Castillo et al. 2010,Hexavalent chromium reduction by bacterial consortia and pure strains from an alkaline industrial effluent,"<strong>AIMS: </strong>To characterize the bacterial consortia and isolates selected for their role in hexavalent chromium removal by adsorption and reduction.<br /><br /><strong>METHODS AND RESULTS: </strong>Bacterial consortia from industrial wastes revealed significant Cr(VI) removal after 15 days when incubated in medium M9 at pH 6·5 and 8·0. The results suggested chromium reduction. The bacterial consortia diversity (T-RFLP based on 16S rRNA gene) indicated a highest number of operational taxonomic units in an alkaline carbonate medium mimicking in situ conditions. However, incubations under such conditions revealed low Cr(VI) removal. Genomic libraries were obtained for the consortia exhibiting optimal Cr(VI) removal (M9 medium at pH 6·5 and 8·0). They revealed the dominance of 16S rRNA gene sequences related to the genera Pseudomonas/Stenotrophomonas or Enterobacter/Halomonas, respectively. Isolates related to Pseudomonas fluorescens and Enterobacter aerogenes were efficient in Cr(VI) reduction and adsorption to the biomass.<br /><br /><strong>CONCLUSIONS: </strong>Cr(VI) reduction was better at neutral pH rather than under in situ conditions (alkaline pH with carbonate). Isolated strains exhibited significant capacity for Cr(VI) reduction and adsorption.<br /><br /><strong>SIGNIFICANCE AND IMPACT OF STUDY: </strong>Bacterial communities from chromium-contaminated industrial wastes as well as isolates were able to remove Cr(VI). The results suggest a good potential for bioremediation of industrial wastes when optimal conditions are applied.","Hexavalent chromium reduction by bacterial consortia and pure strains from an alkaline industrial effluent Abs: <strong>AIMS: </strong>To characterize the bacterial consortia and isolates selected for their role in hexavalent chromium removal by adsorption and reduction.<br /><br /><strong>METHODS AND RESULTS: </strong>Bacterial consortia from industrial wastes revealed significant Cr(VI) removal after 15 days when incubated in medium M9 at pH 6·5 and 8·0. The results suggested chromium reduction. The bacterial consortia diversity (T-RFLP based on 16S rRNA gene) indicated a highest number of operational taxonomic units in an alkaline carbonate medium mimicking in situ conditions. However, incubations under such conditions revealed low Cr(VI) removal. Genomic libraries were obtained for the consortia exhibiting optimal Cr(VI) removal (M9 medium at pH 6·5 and 8·0). They revealed the dominance of 16S rRNA gene sequences related to the genera Pseudomonas/Stenotrophomonas or Enterobacter/Halomonas, respectively. Isolates related to Pseudomonas fluorescens and Enterobacter aerogenes were efficient in Cr(VI) reduction and adsorption to the biomass.<br /><br /><strong>CONCLUSIONS: </strong>Cr(VI) reduction was better at neutral pH rather than under in situ conditions (alkaline pH with carbonate). Isolated strains exhibited significant capacity for Cr(VI) reduction and adsorption.<br /><br /><strong>SIGNIFICANCE AND IMPACT OF STUDY: </strong>Bacterial communities from chromium-contaminated industrial wastes as well as isolates were able to remove Cr(VI). The results suggest a good potential for bioremediation of industrial wastes when optimal conditions are applied."
1231518,Nakayama et al. 2010,[Case of chemical burns caused by hexavalent chromium],"A 25-year-old man fell with his right lower limb into a pool of 40% hexavalent chromium at room temperature. At first, he showed no symptoms, but one hour later he felt itching along his right leg and went to a nearby hospital, where his left leg was washed with water. He was then referred to our hospital for further treatment. On the first day of hospitalization, only brownish areas of discoloration were noted around the inside of the right thigh and lower leg. In spite of our systemic treatment with N-acetylcystein and dimercaprol and local treatment with 10% ascorbic acid, the patient developed deep dermal chemical burns and those area increased from 1% to 5% . On the 12th day of hospitalization, skin transplantation was performed and the postoperative course was satisfactory. Even though injury to the skin caused by hexavalent chromium may seem minor at first, medical staff should be watchful with regard to such chemical burns since they can take a sudden turn for the worse.","[Case of chemical burns caused by hexavalent chromium] Abs: A 25-year-old man fell with his right lower limb into a pool of 40% hexavalent chromium at room temperature. At first, he showed no symptoms, but one hour later he felt itching along his right leg and went to a nearby hospital, where his left leg was washed with water. He was then referred to our hospital for further treatment. On the first day of hospitalization, only brownish areas of discoloration were noted around the inside of the right thigh and lower leg. In spite of our systemic treatment with N-acetylcystein and dimercaprol and local treatment with 10% ascorbic acid, the patient developed deep dermal chemical burns and those area increased from 1% to 5% . On the 12th day of hospitalization, skin transplantation was performed and the postoperative course was satisfactory. Even though injury to the skin caused by hexavalent chromium may seem minor at first, medical staff should be watchful with regard to such chemical burns since they can take a sudden turn for the worse."
1231517,Singh et al. 2011,"Removal of sulphate, COD and Cr(VI) in simulated and real wastewater by sulphate reducing bacteria enrichment in small bioreactor and FTIR study","The present study was conducted to investigate the chromium(VI), COD and sulphate removal efficiency from aqueous solution and treatment of real effluent (CETP) in a small scale bioreactor using sulphate reducing bacteria consortium. Effect of different hydraulic retention times (HRTs), initial metal concentrations, various carbon sources and temperatures were studied on removal of chromium(VI), COD and sulphate. Maximum chromium(VI) and sulphate removal was found to be 96.0% and 82.0%, respectively, at initial concentration of 50 mg l(-1) using lactate as carbon source. However, highest COD removal was 36.2% in medium containing fructose as the carbon source and electron donor. NADH dependent chromate reductase activity was not observed which indicated the anaerobic consortium. Initially consortium medium with a strong negative oxidation reduction potential indicated the reducing activity. The FTIR spectrum of the sulphate reducing bacteria consortium clearly shows the existence of the sulphate ions and signifies that sulfate reducing bacteria have used sulfate during the growth phase.","Removal of sulphate, COD and Cr(VI) in simulated and real wastewater by sulphate reducing bacteria enrichment in small bioreactor and FTIR study Abs: The present study was conducted to investigate the chromium(VI), COD and sulphate removal efficiency from aqueous solution and treatment of real effluent (CETP) in a small scale bioreactor using sulphate reducing bacteria consortium. Effect of different hydraulic retention times (HRTs), initial metal concentrations, various carbon sources and temperatures were studied on removal of chromium(VI), COD and sulphate. Maximum chromium(VI) and sulphate removal was found to be 96.0% and 82.0%, respectively, at initial concentration of 50 mg l(-1) using lactate as carbon source. However, highest COD removal was 36.2% in medium containing fructose as the carbon source and electron donor. NADH dependent chromate reductase activity was not observed which indicated the anaerobic consortium. Initially consortium medium with a strong negative oxidation reduction potential indicated the reducing activity. The FTIR spectrum of the sulphate reducing bacteria consortium clearly shows the existence of the sulphate ions and signifies that sulfate reducing bacteria have used sulfate during the growth phase."
1231516,Hu et al. 2011,"Adsorption of chromium (VI) by ethylenediamine-modified cross-linked magnetic chitosan resin: isotherms, kinetics and thermodynamics","The adsorption of chromium (VI) ions from aqueous solution by ethylenediamine-modified cross-linked magnetic chitosan resin (EMCMCR) was studied in a batch adsorption system. Chromium (VI) removal is pH dependent and the optimum adsorption was observed at pH 2.0. The adsorption rate was extremely fast and the equilibrium was established within 6-10min. The adsorption data could be well interpreted by the Langmuir and Temkin model. The maximum adsorption capacities obtained from the Langmuir model are 51.813mgg(-1), 48.780mgg(-1) and 45.872mgg(-1) at 293, 303 and 313K, respectively. The adsorption process could be described by pseudo-second-order kinetic model. The intraparticle diffusion study revealed that film diffusion might be involved in the present case. Thermodynamic parameters revealed the feasibility, spontaneity and exothermic nature of adsorption. The sorbents were successfully regenerated using 0.1N NaOH solutions.","Adsorption of chromium (VI) by ethylenediamine-modified cross-linked magnetic chitosan resin: isotherms, kinetics and thermodynamics Abs: The adsorption of chromium (VI) ions from aqueous solution by ethylenediamine-modified cross-linked magnetic chitosan resin (EMCMCR) was studied in a batch adsorption system. Chromium (VI) removal is pH dependent and the optimum adsorption was observed at pH 2.0. The adsorption rate was extremely fast and the equilibrium was established within 6-10min. The adsorption data could be well interpreted by the Langmuir and Temkin model. The maximum adsorption capacities obtained from the Langmuir model are 51.813mgg(-1), 48.780mgg(-1) and 45.872mgg(-1) at 293, 303 and 313K, respectively. The adsorption process could be described by pseudo-second-order kinetic model. The intraparticle diffusion study revealed that film diffusion might be involved in the present case. Thermodynamic parameters revealed the feasibility, spontaneity and exothermic nature of adsorption. The sorbents were successfully regenerated using 0.1N NaOH solutions."
1231514,Xie and  Cwiertny 2010,Use of dithionite to extend the reactive lifetime of nanoscale zero-valent iron treatment systems,"Nanoscale zero-valent iron (NZVI) represents a promising approach for source zone control, but concerns over its reactive lifetime might limit application. Here, we demonstrate that dithionite (S?O?²?), a reducing agent for in situ redox manipulation, can restore the reducing capacity of passivated NZVI. Slurries of NZVI were aged in the presence (3 days) and absence (60 days) of dissolved oxygen over a range of pH values (6-8). Upon loss of reactivity toward model pollutants{1,1,1,2-tetrachloroethane, hexavalent chromium [Cr(VI)], nitrobenzene}, aged suspensions were reacted with dithionite, and the composition and reactivity of the dithionite-treated materials were determined. NZVI aging products generally depended on pH and the presence of oxygen, whereas the amount of dithionite influenced the nature and reducing capacity of products generated from reaction with aged NZVI suspensions. Notably, air oxidation at pH ? 8 quickly exhausted NZVI reactivity despite preservation of significant Fe(0) in the particle core. Under these conditions, formation of a passive surface layer hindered the complete transformation of NZVI particles into iron(III) oxides, which occurred at lower pH. Reduction of this passive layer by low dithionite concentrations( 1 g/g of NZVI) restored suspension reactivity to levels equal to, and occasionally greater than, that of unaged NZVI. Multiple dithionite additions further improved pollutant removal, allowing at least a 15-fold increase in Cr(VI) removal [?300 mg of Cr(VI)/g of NZVI] relative to that of as-received NZVI [?20 mg of Cr(VI)/g of NZVI].","Use of dithionite to extend the reactive lifetime of nanoscale zero-valent iron treatment systems Abs: Nanoscale zero-valent iron (NZVI) represents a promising approach for source zone control, but concerns over its reactive lifetime might limit application. Here, we demonstrate that dithionite (S?O?²?), a reducing agent for in situ redox manipulation, can restore the reducing capacity of passivated NZVI. Slurries of NZVI were aged in the presence (3 days) and absence (60 days) of dissolved oxygen over a range of pH values (6-8). Upon loss of reactivity toward model pollutants{1,1,1,2-tetrachloroethane, hexavalent chromium [Cr(VI)], nitrobenzene}, aged suspensions were reacted with dithionite, and the composition and reactivity of the dithionite-treated materials were determined. NZVI aging products generally depended on pH and the presence of oxygen, whereas the amount of dithionite influenced the nature and reducing capacity of products generated from reaction with aged NZVI suspensions. Notably, air oxidation at pH ? 8 quickly exhausted NZVI reactivity despite preservation of significant Fe(0) in the particle core. Under these conditions, formation of a passive surface layer hindered the complete transformation of NZVI particles into iron(III) oxides, which occurred at lower pH. Reduction of this passive layer by low dithionite concentrations( 1 g/g of NZVI) restored suspension reactivity to levels equal to, and occasionally greater than, that of unaged NZVI. Multiple dithionite additions further improved pollutant removal, allowing at least a 15-fold increase in Cr(VI) removal [?300 mg of Cr(VI)/g of NZVI] relative to that of as-received NZVI [?20 mg of Cr(VI)/g of NZVI]."
1231513,Sau et al. 2010,Chromate reduction by cell-free extract of Bacillus firmus KUCr1,"Microbial enzymatic reduction of a toxic form of chromium [Cr(VI)] has been considered as an effective method for bioremediation of this metal. This study reports on the in vitro reduction of Cr(VI) using cell-free extracts from a Cr(VI) reducing Bacillus firmus KUCr1 strain. Chromium reductase was found to be constitutive and its activity was observed both in soluble cell fractions (S12 and S150 and membrane cell fraction (P150). The reductase activity of S12 fraction was found to be optimal at 40 microM Cr(VI) with enzyme concentration equivalent to 0.493 mg protein/ml. Enzyme activity was dependent on NADH or NADPH as electron donor; optimal temperature and pH for better enzyme activity were 70 degrees C and 5.6, respectively. The Km value of the reductase was 58.33 microM chromate having a V(max) of 11.42 microM/min/mg protein. The metabolic inhibitor like sodium azide inhibited reductase activity of membrane fraction of the cell-free extract. Metal ions like Cu2+, Co2+, Ni2+ and As3+ stimulated the enzyme but others, such as Ag+, Hg2+, Zn2+, Mn2+, Cd2+ and Pb2+, inhibited Cr(VI) reductase activity.","Chromate reduction by cell-free extract of Bacillus firmus KUCr1 Abs: Microbial enzymatic reduction of a toxic form of chromium [Cr(VI)] has been considered as an effective method for bioremediation of this metal. This study reports on the in vitro reduction of Cr(VI) using cell-free extracts from a Cr(VI) reducing Bacillus firmus KUCr1 strain. Chromium reductase was found to be constitutive and its activity was observed both in soluble cell fractions (S12 and S150 and membrane cell fraction (P150). The reductase activity of S12 fraction was found to be optimal at 40 microM Cr(VI) with enzyme concentration equivalent to 0.493 mg protein/ml. Enzyme activity was dependent on NADH or NADPH as electron donor; optimal temperature and pH for better enzyme activity were 70 degrees C and 5.6, respectively. The Km value of the reductase was 58.33 microM chromate having a V(max) of 11.42 microM/min/mg protein. The metabolic inhibitor like sodium azide inhibited reductase activity of membrane fraction of the cell-free extract. Metal ions like Cu2+, Co2+, Ni2+ and As3+ stimulated the enzyme but others, such as Ag+, Hg2+, Zn2+, Mn2+, Cd2+ and Pb2+, inhibited Cr(VI) reductase activity."
1231512,Raddatz et al. 2011,Cr stable isotopes in Snake River Plain aquifer groundwater: evidence for natural reduction of dissolved Cr(VI),"At Idaho National Laboratory, Cr(VI) concentrations in a groundwater plume once exceeded regulatory limits in some monitoring wells but have generally decreased over time. This study used Cr stable isotope measurements to determine if part of this decrease resulted from removal of Cr(VI) via reduction to insoluble Cr(III). Although waters in the study area contain dissolved oxygen, the basalt host rock contains abundant Fe(II) and may contain reducing microenvironments or aerobic microbes that reduce Cr(VI). In some contaminated locations, (53)Cr/(52)Cr ratios are close to that of the contaminant source, indicating a lack of Cr(VI) reduction. In other locations, ratios are elevated. Part of this shift may be caused by mixing with natural background Cr(VI), which is present at low concentrations but in some locations has elevated (53)Cr/(52)Cr. Some contaminated wells have (53)Cr/(52)Cr ratios greater than the maximum attainable by mixing between the inferred contaminant and the range of natural background observed in several uncontaminated wells, suggesting that Cr(VI) reduction has occurred. Definitive proof of reduction would require additional evidence. Depth profiles of (53)Cr/(52)Cr suggest that reduction occurs immediately below the water table, where basalts are likely least weathered and most reactive, and is weak or nonexistent at greater depth.","Cr stable isotopes in Snake River Plain aquifer groundwater: evidence for natural reduction of dissolved Cr(VI) Abs: At Idaho National Laboratory, Cr(VI) concentrations in a groundwater plume once exceeded regulatory limits in some monitoring wells but have generally decreased over time. This study used Cr stable isotope measurements to determine if part of this decrease resulted from removal of Cr(VI) via reduction to insoluble Cr(III). Although waters in the study area contain dissolved oxygen, the basalt host rock contains abundant Fe(II) and may contain reducing microenvironments or aerobic microbes that reduce Cr(VI). In some contaminated locations, (53)Cr/(52)Cr ratios are close to that of the contaminant source, indicating a lack of Cr(VI) reduction. In other locations, ratios are elevated. Part of this shift may be caused by mixing with natural background Cr(VI), which is present at low concentrations but in some locations has elevated (53)Cr/(52)Cr. Some contaminated wells have (53)Cr/(52)Cr ratios greater than the maximum attainable by mixing between the inferred contaminant and the range of natural background observed in several uncontaminated wells, suggesting that Cr(VI) reduction has occurred. Definitive proof of reduction would require additional evidence. Depth profiles of (53)Cr/(52)Cr suggest that reduction occurs immediately below the water table, where basalts are likely least weathered and most reactive, and is weak or nonexistent at greater depth."
1231509,Masood and  Malik 2011,Hexavalent chromium reduction by Bacillus sp. strain FM1 isolated from heavy-metal contaminated soil,"A Cr(VI) reducing bacterial strain FM1 was isolated from heavy metal contaminated agricultural soil irrigated with tannery effluents of Jajmau, Kanpur (India), and was identified as Bacillus sp. on the basis of biochemical methods and 16S rDNA gene sequence analysis. FM1 strain was found to be resistant to some toxic heavy metals (Cr(VI), Cr(III), Cu²+, Co²+, Cd²+, Ni²+ and Zn²+) up to several fold concentrations to the normal levels occurring in highly polluted region. FM1 was resistant to very high concentration of Cr(VI) (1,000 mg/L) and completely reduced 100 mg/L Cr(VI) within 48 h. Factors (pH, temperature, initial Cr(VI) concentration) affecting Cr(VI) reduction under culture condition were also evaluated. Reduction was optimum at 37 °C and pH 8. Cr(VI) reduction was enhanced by addition of glucose. The presence of heavy metal cations, such as Cu²+, Co²+, Cd²+, Ni²+ and Zn²+ showed differential effect on reduction. Since strain FM1 could grow in the presence of significant concentrations of metals and due to high Cr(VI) reduction ability, this bacterium may be potentially applicable in Cr(VI) detoxification.","Hexavalent chromium reduction by Bacillus sp. strain FM1 isolated from heavy-metal contaminated soil Abs: A Cr(VI) reducing bacterial strain FM1 was isolated from heavy metal contaminated agricultural soil irrigated with tannery effluents of Jajmau, Kanpur (India), and was identified as Bacillus sp. on the basis of biochemical methods and 16S rDNA gene sequence analysis. FM1 strain was found to be resistant to some toxic heavy metals (Cr(VI), Cr(III), Cu²+, Co²+, Cd²+, Ni²+ and Zn²+) up to several fold concentrations to the normal levels occurring in highly polluted region. FM1 was resistant to very high concentration of Cr(VI) (1,000 mg/L) and completely reduced 100 mg/L Cr(VI) within 48 h. Factors (pH, temperature, initial Cr(VI) concentration) affecting Cr(VI) reduction under culture condition were also evaluated. Reduction was optimum at 37 °C and pH 8. Cr(VI) reduction was enhanced by addition of glucose. The presence of heavy metal cations, such as Cu²+, Co²+, Cd²+, Ni²+ and Zn²+ showed differential effect on reduction. Since strain FM1 could grow in the presence of significant concentrations of metals and due to high Cr(VI) reduction ability, this bacterium may be potentially applicable in Cr(VI) detoxification."
1231508,Piau and  Aspray 2011,Effectiveness and longevity of a green/food waste derived compost packed column to reduce Cr(VI) contamination in groundwater,"PAS100 accredited compost derived from green and food waste sources was used to remediate groundwater containing Cr(VI) at a historically contaminated site in Falkirk, Scotland, UK. The compost was mixed with gravel at a ratio of 1:1 (v/v) to provide a reactive bedding material in an upflow column. The Cr(VI) concentration in the groundwater (inlet) ranged from 0.5 to 7.8 mg L(-1) during the 168 d trial period. After an acclimation period of 54 d, the flow rate was increased in the column from 5.8 to 8 mL min(-1). Cr(VI) in the outlet was less than 100 ?g L(-1) up to 134 d, after which the concentration steadily increased till 168 d. Compost analysis following completion of the trial confirmed that Cr(VI) was captured within the column. Anaerobic microbial reduction of Cr(VI) to Cr(III) was thought to be a key mechanism responsible for the longevity of the system to remove Cr(VI) from the groundwater. Requiring no additional organic carbon or nitrogen during the trial period, this setup represents a cost-effective treatment approach for low flow-through systems.","Effectiveness and longevity of a green/food waste derived compost packed column to reduce Cr(VI) contamination in groundwater Abs: PAS100 accredited compost derived from green and food waste sources was used to remediate groundwater containing Cr(VI) at a historically contaminated site in Falkirk, Scotland, UK. The compost was mixed with gravel at a ratio of 1:1 (v/v) to provide a reactive bedding material in an upflow column. The Cr(VI) concentration in the groundwater (inlet) ranged from 0.5 to 7.8 mg L(-1) during the 168 d trial period. After an acclimation period of 54 d, the flow rate was increased in the column from 5.8 to 8 mL min(-1). Cr(VI) in the outlet was less than 100 ?g L(-1) up to 134 d, after which the concentration steadily increased till 168 d. Compost analysis following completion of the trial confirmed that Cr(VI) was captured within the column. Anaerobic microbial reduction of Cr(VI) to Cr(III) was thought to be a key mechanism responsible for the longevity of the system to remove Cr(VI) from the groundwater. Requiring no additional organic carbon or nitrogen during the trial period, this setup represents a cost-effective treatment approach for low flow-through systems."
1231506,Dalcin et al. 2011,Evaluation of hexavalent chromium removal in a continuous biological filter with the use of central composite design (CCD),"Hexavalent chromium is frequently found in industrial effluents as a result of the industrial applications of this compound and its anti-corrosive features. However, hexavalent chromium is extremely toxic, and its discharge in water is regulated, with a maximum limit of 0.1 mg/L in accordance with legislation established by CONAMA-Brazil (no. 397, April 3, 2008). To achieve lower discharge values, it is necessary to reduce from Cr(VI) to Cr(III), which is less toxic, and an economic alternative involves biological removal of this compound. Residence time distributions (RTDs) were measured to evaluate the behavior of actual biofilter operation conditions in a biofilter flow. The medium residence time distributions used were 8 and 24 h (recommended by the legislation). To optimize this process, a central composite design was used, considering the initial chromium concentration and pH as the independent variables and the removal of hexavalent chromium as the response. The boundary curves and surface response showed optimal behavior at 3.94 mg/L [Cr(0)] and a pH of 6.2. The removal process of hexavalent chromium is mathematically described by the Michaelis-Menten kinetic model. This model appropriately represents the variation of chromium concentration along the bioreactor.","Evaluation of hexavalent chromium removal in a continuous biological filter with the use of central composite design (CCD) Abs: Hexavalent chromium is frequently found in industrial effluents as a result of the industrial applications of this compound and its anti-corrosive features. However, hexavalent chromium is extremely toxic, and its discharge in water is regulated, with a maximum limit of 0.1 mg/L in accordance with legislation established by CONAMA-Brazil (no. 397, April 3, 2008). To achieve lower discharge values, it is necessary to reduce from Cr(VI) to Cr(III), which is less toxic, and an economic alternative involves biological removal of this compound. Residence time distributions (RTDs) were measured to evaluate the behavior of actual biofilter operation conditions in a biofilter flow. The medium residence time distributions used were 8 and 24 h (recommended by the legislation). To optimize this process, a central composite design was used, considering the initial chromium concentration and pH as the independent variables and the removal of hexavalent chromium as the response. The boundary curves and surface response showed optimal behavior at 3.94 mg/L [Cr(0)] and a pH of 6.2. The removal process of hexavalent chromium is mathematically described by the Michaelis-Menten kinetic model. This model appropriately represents the variation of chromium concentration along the bioreactor."
1231505,Chen et al. 2011,Surface-modified Phanerochaete chrysosporium as a biosorbent for Cr(VI)-contaminated wastewater,"To improve the removal efficiency of heavy metals from wastewater, the surface of a fungal biomass was modified to obtain a high-capacity biosorbent for Cr(VI) in wastewater. The effects of pH, initial concentration, and sorption time on Cr(VI) removal by polyethylenimine (PEI)-modified Phanerochaete chrysosporium were investigated. The biomass adsorption capacity was significantly dependent on the pH of the solution, and the optimum pH was approximately 3.0. The maximum removal for Cr(VI) was 344.8 mg/g as determined with the Langmuir adsorption isotherm. Pseudo-first-order Lagergren model is better than pseudo-second-order Lagergren model when simulating the kinetic experiment results. Furthermore, an amount of Cr(VI) was reduced to Cr(III), indicating that some reactions occurred on the surface of the biomass leading to the reduction of Cr(VI). The point of zero potential for the modified biomass increased from an initial pH of 3.0 to a much higher value of 10.8, indicating that the PEI-modified biomass is better than the pristine biomass for adsorption of anionic adsorbates. Results showed that the PEI-modified biosorbent presented high efficiency in treating Cr(VI)-contaminated wastewater.","Surface-modified Phanerochaete chrysosporium as a biosorbent for Cr(VI)-contaminated wastewater Abs: To improve the removal efficiency of heavy metals from wastewater, the surface of a fungal biomass was modified to obtain a high-capacity biosorbent for Cr(VI) in wastewater. The effects of pH, initial concentration, and sorption time on Cr(VI) removal by polyethylenimine (PEI)-modified Phanerochaete chrysosporium were investigated. The biomass adsorption capacity was significantly dependent on the pH of the solution, and the optimum pH was approximately 3.0. The maximum removal for Cr(VI) was 344.8 mg/g as determined with the Langmuir adsorption isotherm. Pseudo-first-order Lagergren model is better than pseudo-second-order Lagergren model when simulating the kinetic experiment results. Furthermore, an amount of Cr(VI) was reduced to Cr(III), indicating that some reactions occurred on the surface of the biomass leading to the reduction of Cr(VI). The point of zero potential for the modified biomass increased from an initial pH of 3.0 to a much higher value of 10.8, indicating that the PEI-modified biomass is better than the pristine biomass for adsorption of anionic adsorbates. Results showed that the PEI-modified biosorbent presented high efficiency in treating Cr(VI)-contaminated wastewater."
1231503,Meyskens and  Yang 2011,Thinking about the role (largely ignored) of heavy metals in cancer prevention: hexavalent chromium and melanoma as a case in point,"Ultraviolet (UV) light exposure accounts for only 40-50% of the attributable risk for cutaneous melanoma (CM); also classical UV-induced lesions are rare in melanomas (especially among CM with NRAS or BRAF mutations). It is therefore likely that an additional environmental factor exists as familial and genetic factors play a role in less than 5%. A large amount of (largely forgotten) epidemiologic data indicates that heavy metal exposure is strongly associated with the development of CM. Also, epidemiologic studies of patients with joint replacement indicate a marked subsequent time-related increase in melanoma in patients with metal-on-metal hip arthroplasties. In these patients chromium and cobalt levels rise to 10x normal and stay elevated at levels two- to threefold normal for at least 10 years. Chromium is widely used in industry for its anticorrosive and steel-strengthening properties and is widespread in everyday materials. Our hypothesis is therefore that chromium, alone or in conjunction with UV, plays a major role in the pathogenesis of CM. We have incubated human neonatal melanocytes for more than 10 weeks in the presence of a wide range and concentrations of metals without effect except by hexavalent chromium Cr(VI)and to a lesser degree Co²(+). After prolonged culture, chromium-incubated cells produced foci and when replated secondary colonies formed. We have just begun to study this phenomenon in more detail and studies without and with different wavelengths of UV will be explored. Of interest is that aneuploidy (a universal chromosomal change in cutaneous melanoma) in lymphocytes in patients with hip-on-hip metal prostheses has been demonstrated by others.","Thinking about the role (largely ignored) of heavy metals in cancer prevention: hexavalent chromium and melanoma as a case in point Abs: Ultraviolet (UV) light exposure accounts for only 40-50% of the attributable risk for cutaneous melanoma (CM); also classical UV-induced lesions are rare in melanomas (especially among CM with NRAS or BRAF mutations). It is therefore likely that an additional environmental factor exists as familial and genetic factors play a role in less than 5%. A large amount of (largely forgotten) epidemiologic data indicates that heavy metal exposure is strongly associated with the development of CM. Also, epidemiologic studies of patients with joint replacement indicate a marked subsequent time-related increase in melanoma in patients with metal-on-metal hip arthroplasties. In these patients chromium and cobalt levels rise to 10x normal and stay elevated at levels two- to threefold normal for at least 10 years. Chromium is widely used in industry for its anticorrosive and steel-strengthening properties and is widespread in everyday materials. Our hypothesis is therefore that chromium, alone or in conjunction with UV, plays a major role in the pathogenesis of CM. We have incubated human neonatal melanocytes for more than 10 weeks in the presence of a wide range and concentrations of metals without effect except by hexavalent chromium Cr(VI)and to a lesser degree Co²(+). After prolonged culture, chromium-incubated cells produced foci and when replated secondary colonies formed. We have just begun to study this phenomenon in more detail and studies without and with different wavelengths of UV will be explored. Of interest is that aneuploidy (a universal chromosomal change in cutaneous melanoma) in lymphocytes in patients with hip-on-hip metal prostheses has been demonstrated by others."
1231502,Lee and  Kim 2010,Occupational respiratory cancer in Korea,"Malignant mesothelioma and lung cancer are representative examples of occupational cancer. Lung cancer is the leading cause of cancer death, and the incidence of malignant mesothelioma is expected to increase sharply in the near future. Although information about lung carcinogen exposure is limited, it is estimated that the number of workers exposed to carcinogens has declined. The first official case of occupational cancer was malignant mesothelioma caused by asbestos exposure in the asbestos textile industry in 1992. Since then, compensation for occupational respiratory cancer has increased. The majority of compensated lung cancer was due to underlying pneumoconiosis. Other main causative agents of occupational lung cancer included asbestos, hexavalent chromium, and crystalline silica. Related jobs included welders, foundry workers, platers, plumbers, and vehicle maintenance workers. Compensated malignant mesotheliomas were associated with asbestos exposure. Epidemiologic studies conducted in Korea have indicated an elevated risk of lung cancer in pneumoconiosis patients, foundry workers, and asbestos textile workers. Occupational respiratory cancer has increased during the last 10 to 20 yr though carcinogen-exposed population has declined in the same period. More efforts to advance the systems for the investigation, prevention and management of occupational respiratory cancer are needed.","Occupational respiratory cancer in Korea Abs: Malignant mesothelioma and lung cancer are representative examples of occupational cancer. Lung cancer is the leading cause of cancer death, and the incidence of malignant mesothelioma is expected to increase sharply in the near future. Although information about lung carcinogen exposure is limited, it is estimated that the number of workers exposed to carcinogens has declined. The first official case of occupational cancer was malignant mesothelioma caused by asbestos exposure in the asbestos textile industry in 1992. Since then, compensation for occupational respiratory cancer has increased. The majority of compensated lung cancer was due to underlying pneumoconiosis. Other main causative agents of occupational lung cancer included asbestos, hexavalent chromium, and crystalline silica. Related jobs included welders, foundry workers, platers, plumbers, and vehicle maintenance workers. Compensated malignant mesotheliomas were associated with asbestos exposure. Epidemiologic studies conducted in Korea have indicated an elevated risk of lung cancer in pneumoconiosis patients, foundry workers, and asbestos textile workers. Occupational respiratory cancer has increased during the last 10 to 20 yr though carcinogen-exposed population has declined in the same period. More efforts to advance the systems for the investigation, prevention and management of occupational respiratory cancer are needed."
1231501,Banu et al. 2011,"Hexavalent chromium-induced apoptosis of granulosa cells involves selective sub-cellular translocation of Bcl-2 members, ERK1/2 and p53","Hexavalent chromium (CrVI) has been widely used in industries throughout the world. Increased usage of CrVI and atmospheric emission of CrVI from catalytic converters of automobiles, and its improper disposal causes various health hazards including female infertility. Recently we have reported that lactational exposure to CrVI induced a delay/arrest in follicular development at the secondary follicular stage. In order to investigate the underlying mechanism, primary cultures of rat granulosa cells were treated with 10 ?M potassium dichromate (CrVI) for 12 and 24h, with or without vitamin C pre-treatment for 24h. The effects of CrVI on intrinsic apoptotic pathway(s) were investigated. Our data indicated that CrVI: (i) induced DNA fragmentation and increased apoptosis, (ii) increased cytochrome c release from the mitochondria to cytosol, (iii) downregulated anti-apoptotic Bcl-2, Bcl-XL, HSP70 and HSP90; upregulated pro-apoptotic BAX and BAD, (iv) altered translocation of Bcl-2, Bcl-XL, BAX, BAD, HSP70 and HSP90 to the mitochondria, (v) upregulated p-ERK and p-JNK, and selectively translocated p-ERK to the mitochondria and nucleus, (vi) activated caspase-3 and PARP, and (vii) increased phosphorylation of p53 at ser-6, ser-9, ser-15, ser-20, ser-37, ser-46 and ser-392, increased p53 transcriptional activation, and downregulated MDM-2. Vitamin C pre-treatment mitigated CrVI effects on apoptosis and related pathways. Our study, for the first time provides a clear insight into the effect of CrVI on multiple pathways that lead to apoptosis of granulosa cells which could be mitigated by vitamin C.","Hexavalent chromium-induced apoptosis of granulosa cells involves selective sub-cellular translocation of Bcl-2 members, ERK1/2 and p53 Abs: Hexavalent chromium (CrVI) has been widely used in industries throughout the world. Increased usage of CrVI and atmospheric emission of CrVI from catalytic converters of automobiles, and its improper disposal causes various health hazards including female infertility. Recently we have reported that lactational exposure to CrVI induced a delay/arrest in follicular development at the secondary follicular stage. In order to investigate the underlying mechanism, primary cultures of rat granulosa cells were treated with 10 ?M potassium dichromate (CrVI) for 12 and 24h, with or without vitamin C pre-treatment for 24h. The effects of CrVI on intrinsic apoptotic pathway(s) were investigated. Our data indicated that CrVI: (i) induced DNA fragmentation and increased apoptosis, (ii) increased cytochrome c release from the mitochondria to cytosol, (iii) downregulated anti-apoptotic Bcl-2, Bcl-XL, HSP70 and HSP90; upregulated pro-apoptotic BAX and BAD, (iv) altered translocation of Bcl-2, Bcl-XL, BAX, BAD, HSP70 and HSP90 to the mitochondria, (v) upregulated p-ERK and p-JNK, and selectively translocated p-ERK to the mitochondria and nucleus, (vi) activated caspase-3 and PARP, and (vii) increased phosphorylation of p53 at ser-6, ser-9, ser-15, ser-20, ser-37, ser-46 and ser-392, increased p53 transcriptional activation, and downregulated MDM-2. Vitamin C pre-treatment mitigated CrVI effects on apoptosis and related pathways. Our study, for the first time provides a clear insight into the effect of CrVI on multiple pathways that lead to apoptosis of granulosa cells which could be mitigated by vitamin C."
1231500,Kieling-Rubio et al. 2010,Germination and sporophytic development of Regnellidium diphyllum Lindman (Marsileaceae) in the presence of hexavalent chromium,"Regnellidium diphyllum Lindman is a heterosporous fern, growing in aquatic environments and surrounding wetlands, which is assumed to be threatened by increasing water pollution and disappearance of its natural habitats. Among contaminants, hexavalent chromium - Cr(VI) - is known to be present in effluents from some leather tanning factories. Megaspore germination tests were performed using Meyer's solution, at concentrations 0 (control), 0.1, 0.5, 1, 5, 10, 15, 20, 30, 50, and 80 mg.L?¹, from a standard solution of Titrisol® 1000 mg.L?¹. The primary development of apomictic sporophytes was studied using solutions containing 0.025 to 4.8 mg.L?¹ of Cr(VI). The experiments were conducted in a growth chamber at 24 ± 1 ºC and for a 12-hour photoperiod under fluorescent lights, providing a nominal irradiance of 77 µmol.m?²/s. Significant differences in megaspore germination, with subsequent sporophytic development, were verified from 0.5 mg.L?¹ Cr(VI) concentration onwards. Growth of primary root and primary and secondary leaves was significantly reduced at 3.2 mg.L?¹ Cr(VI) concentration or higher. Considering the pollution from Cr(VI) in some areas of R. diphyllum natural occurrence, these data indicate that low reproductive rates and disappearance of populations are likely to occur in these situations.","Germination and sporophytic development of Regnellidium diphyllum Lindman (Marsileaceae) in the presence of hexavalent chromium Abs: Regnellidium diphyllum Lindman is a heterosporous fern, growing in aquatic environments and surrounding wetlands, which is assumed to be threatened by increasing water pollution and disappearance of its natural habitats. Among contaminants, hexavalent chromium - Cr(VI) - is known to be present in effluents from some leather tanning factories. Megaspore germination tests were performed using Meyer's solution, at concentrations 0 (control), 0.1, 0.5, 1, 5, 10, 15, 20, 30, 50, and 80 mg.L?¹, from a standard solution of Titrisol® 1000 mg.L?¹. The primary development of apomictic sporophytes was studied using solutions containing 0.025 to 4.8 mg.L?¹ of Cr(VI). The experiments were conducted in a growth chamber at 24 ± 1 ºC and for a 12-hour photoperiod under fluorescent lights, providing a nominal irradiance of 77 µmol.m?²/s. Significant differences in megaspore germination, with subsequent sporophytic development, were verified from 0.5 mg.L?¹ Cr(VI) concentration onwards. Growth of primary root and primary and secondary leaves was significantly reduced at 3.2 mg.L?¹ Cr(VI) concentration or higher. Considering the pollution from Cr(VI) in some areas of R. diphyllum natural occurrence, these data indicate that low reproductive rates and disappearance of populations are likely to occur in these situations."
1231498,Kavita et al. 2011,Hexavalent chromium sorption by biomass of chromium tolerant Pythium sp,"The removal of Cr(VI) from aqueous solutions by live and pretreated fungal biomass of Pythium sp was investigated in a batch mode. The influence of biomass dose, solution pH, initial metal ion concentration, temperature and pretreatment of biomass on biosorption efficiency was studied. The acid pretreated biomass adsorbed 1.7 times more hexavalent chromium in comparison to untreated biomass. The chromium removal rate increased with decrease in pH and increase in Cr(VI) concentration, biomass dose and temperature. The adsorption data was described well by Freundlich isotherm model. Evaluation of biosorption mechanism using infrared spectroscopy showed the involvement of positively charged amino groups in Cr(VI) biosorption. The biosorption of Cr(VI) by Pythium sp. followed second order kinetics, the biosorption process was found to be spontaneous and endothermic with high affinity of biomass for Cr(VI).","Hexavalent chromium sorption by biomass of chromium tolerant Pythium sp Abs: The removal of Cr(VI) from aqueous solutions by live and pretreated fungal biomass of Pythium sp was investigated in a batch mode. The influence of biomass dose, solution pH, initial metal ion concentration, temperature and pretreatment of biomass on biosorption efficiency was studied. The acid pretreated biomass adsorbed 1.7 times more hexavalent chromium in comparison to untreated biomass. The chromium removal rate increased with decrease in pH and increase in Cr(VI) concentration, biomass dose and temperature. The adsorption data was described well by Freundlich isotherm model. Evaluation of biosorption mechanism using infrared spectroscopy showed the involvement of positively charged amino groups in Cr(VI) biosorption. The biosorption of Cr(VI) by Pythium sp. followed second order kinetics, the biosorption process was found to be spontaneous and endothermic with high affinity of biomass for Cr(VI)."
1231497,Zheng et al. 2011,"Characterization of hexavalent chromium interaction with Sargassum by X-ray absorption fine structure spectroscopy, X-ray photoelectron spectroscopy, and quantum chemistry calculation","Hexavalent chromium represents higher toxicity in aqueous solutions. It can be removed by such low-cost biosorbents as Sargassum sp. In this study, X-ray absorption fine structure spectroscopy, X-ray photoelectron spectroscopy, and quantum chemistry (QC) calculation were used to study the interactions between hexavalent chromium and Sargassum sp. during the biosorption. It was found that most of the adsorbed Cr(VI) ions were reduced to Cr(III) after the biosorption. The electrons for the reduction of Cr(VI) were possibly supplied from the Sargassum biomass, some organic compounds of which were oxidized. Cr(III) ions were coordinated with the oxygen atoms from either carboxyl or hydroxyl functional groups to form an octahedral structural metal complex. The coordination numbers of the formed Cr complex were 4-6, and bond length of Cr-O was 1.98Å. QC calculation proved the possible formation of the Cr(III) metal complex, and revealed that carboxyl from biomass could be strongly bound with Cr(III). A three-step removal mechanism of Cr(VI) by Sargassum was proposed.","Characterization of hexavalent chromium interaction with Sargassum by X-ray absorption fine structure spectroscopy, X-ray photoelectron spectroscopy, and quantum chemistry calculation Abs: Hexavalent chromium represents higher toxicity in aqueous solutions. It can be removed by such low-cost biosorbents as Sargassum sp. In this study, X-ray absorption fine structure spectroscopy, X-ray photoelectron spectroscopy, and quantum chemistry (QC) calculation were used to study the interactions between hexavalent chromium and Sargassum sp. during the biosorption. It was found that most of the adsorbed Cr(VI) ions were reduced to Cr(III) after the biosorption. The electrons for the reduction of Cr(VI) were possibly supplied from the Sargassum biomass, some organic compounds of which were oxidized. Cr(III) ions were coordinated with the oxygen atoms from either carboxyl or hydroxyl functional groups to form an octahedral structural metal complex. The coordination numbers of the formed Cr complex were 4-6, and bond length of Cr-O was 1.98Å. QC calculation proved the possible formation of the Cr(III) metal complex, and revealed that carboxyl from biomass could be strongly bound with Cr(III). A three-step removal mechanism of Cr(VI) by Sargassum was proposed."
1231496,Barmo et al. 2011,Pleiotropic effects of hexavalent chromium (CrVI) in Mytilus galloprovincialis digestive gland,"Hexavalent Chromium Cr(VI) is an important contaminant considered as a model oxidative toxicant released from both domestic and industrial effluents, and represents the predominant chemical form of the metal in aquatic ecosystems. On the other hand, in mammals the reduced form Cr(III) is considered an essential microelement, involved in regulation of lipid and carbohydrate metabolism; moreover, recent evidence suggests that Cr may have endocrine effects. In this work, the effects of Cr(VI) were investigated in the digestive gland of the marine bivalve Mytilus galloprovincialis. Mussels were exposed to 0.1-1-10-100 ?g Cr(VI) L(-1) animal(-1) for 96 h. At 100 ?g L(-1), a large increase in total Cr tissue content was observed; in these conditions, the lysosomal membranes were completely destabilized, whereas other lysosomal biomarkers (neutral lipids-NL and lipofuscin-LF), as well as different enzyme activities and gene expression were unaffected, this indicating severe stress conditions in the tissue. On the other hand, at lower concentrations, changes in other histochemical, biochemical and molecular endpoints were observed. In particular, at both 1 and 10 ?g L(-1), lysosomal destabilization was associated with significant NL and LF accumulation; however, no changes in catalase and GSH transferase (GST) activities were observed. At the same concentrations, GSSG reductase (GSR) activity was significantly increased, this probably reflecting the recycling of GSSG produced in the GSH-mediated intracellular reduction of Cr(VI). Increased activities of the key glycolytic enzymes PFK (phosphofructokinase) and PK (pyruvate kinase) were also observed, indicating that Cr(VI) could affect carbohydrate metabolism. Cr(VI) induced downregulation or no effects on the expression of metallothioneins MT10 and MT20, except for an increase in MT20 transcription in males. Moreover, significant up-regulation of the Mytilus estrogen receptor MeER2 and serotonin receptor (5-HTR) were observed in both sexes. The results demonstrate that exposure to Cr(VI) in the low ppb range did not result in strong toxicity or oxidative stress conditions in mussel digestive gland. On the other hand, our data support the hypothesis that low concentrations of the metal can exert pleiotropic effects on mussel physiology, from modulation of lipid and carbohydrate metabolism, to effects on the expression of estrogen-responsive genes.","Pleiotropic effects of hexavalent chromium (CrVI) in Mytilus galloprovincialis digestive gland Abs: Hexavalent Chromium Cr(VI) is an important contaminant considered as a model oxidative toxicant released from both domestic and industrial effluents, and represents the predominant chemical form of the metal in aquatic ecosystems. On the other hand, in mammals the reduced form Cr(III) is considered an essential microelement, involved in regulation of lipid and carbohydrate metabolism; moreover, recent evidence suggests that Cr may have endocrine effects. In this work, the effects of Cr(VI) were investigated in the digestive gland of the marine bivalve Mytilus galloprovincialis. Mussels were exposed to 0.1-1-10-100 ?g Cr(VI) L(-1) animal(-1) for 96 h. At 100 ?g L(-1), a large increase in total Cr tissue content was observed; in these conditions, the lysosomal membranes were completely destabilized, whereas other lysosomal biomarkers (neutral lipids-NL and lipofuscin-LF), as well as different enzyme activities and gene expression were unaffected, this indicating severe stress conditions in the tissue. On the other hand, at lower concentrations, changes in other histochemical, biochemical and molecular endpoints were observed. In particular, at both 1 and 10 ?g L(-1), lysosomal destabilization was associated with significant NL and LF accumulation; however, no changes in catalase and GSH transferase (GST) activities were observed. At the same concentrations, GSSG reductase (GSR) activity was significantly increased, this probably reflecting the recycling of GSSG produced in the GSH-mediated intracellular reduction of Cr(VI). Increased activities of the key glycolytic enzymes PFK (phosphofructokinase) and PK (pyruvate kinase) were also observed, indicating that Cr(VI) could affect carbohydrate metabolism. Cr(VI) induced downregulation or no effects on the expression of metallothioneins MT10 and MT20, except for an increase in MT20 transcription in males. Moreover, significant up-regulation of the Mytilus estrogen receptor MeER2 and serotonin receptor (5-HTR) were observed in both sexes. The results demonstrate that exposure to Cr(VI) in the low ppb range did not result in strong toxicity or oxidative stress conditions in mussel digestive gland. On the other hand, our data support the hypothesis that low concentrations of the metal can exert pleiotropic effects on mussel physiology, from modulation of lipid and carbohydrate metabolism, to effects on the expression of estrogen-responsive genes."
1231495,Proctor et al. 2011,A response to &quot;A quantitative assessment of the carcinogenicity of hexavalent chromium by the oral route and its relevance to human exposure&quot,,A response to &quot;A quantitative assessment of the carcinogenicity of hexavalent chromium by the oral route and its relevance to human exposure&quot Abs: 
1231494,Dogan et al. 2011,Chromium(VI) bioremoval by Pseudomonas bacteria: role of microbial exudates for natural attenuation and biotreatment of Cr(VI) contamination,"Laboratory batch and column experiments were conducted to investigate the role of microbial exudates, e.g., exopolymeric substance (EPS) and alginic acid, on microbial Cr(VI) reduction by two different Pseudomonas strains (P. putida P18 and P. aeuroginosa P16) as a method for treating subsurface environment contaminated with Cr(VI). Our results indicate that microbial exudates significantly enhanced microbial Cr(VI) reduction rates by forming less toxic and highly soluble organo-Cr(III) complexes despite the fact Cr(III) has a very low solubility under the experimental conditions studied (e.g., pH 7). The formation of soluble organo-Cr(III) complexes led to the protection of the cells and chromate reductases from inactivation. In systems with no organic ligands, soluble organo-Cr(III) end products were formed between Cr(III) and the EPS directly released by bacteria due to cell lysis. Our results also provide evidence that cell lysis played an important role in microbial Cr(VI) reduction by Pseudomonas bacteria due to the release of constitutive reductases that intracellularly and/or extracellularly catalyzed the reduction of Cr(VI) to Cr(III). The overall results highlight the need for incorporation of the release and formation of organo-Cr(III) complexes into reactive transport models to more accurately design and monitor in situ microbial remediation techniques for the treatment of subsurface systems contaminated with Cr(VI).","Chromium(VI) bioremoval by Pseudomonas bacteria: role of microbial exudates for natural attenuation and biotreatment of Cr(VI) contamination Abs: Laboratory batch and column experiments were conducted to investigate the role of microbial exudates, e.g., exopolymeric substance (EPS) and alginic acid, on microbial Cr(VI) reduction by two different Pseudomonas strains (P. putida P18 and P. aeuroginosa P16) as a method for treating subsurface environment contaminated with Cr(VI). Our results indicate that microbial exudates significantly enhanced microbial Cr(VI) reduction rates by forming less toxic and highly soluble organo-Cr(III) complexes despite the fact Cr(III) has a very low solubility under the experimental conditions studied (e.g., pH 7). The formation of soluble organo-Cr(III) complexes led to the protection of the cells and chromate reductases from inactivation. In systems with no organic ligands, soluble organo-Cr(III) end products were formed between Cr(III) and the EPS directly released by bacteria due to cell lysis. Our results also provide evidence that cell lysis played an important role in microbial Cr(VI) reduction by Pseudomonas bacteria due to the release of constitutive reductases that intracellularly and/or extracellularly catalyzed the reduction of Cr(VI) to Cr(III). The overall results highlight the need for incorporation of the release and formation of organo-Cr(III) complexes into reactive transport models to more accurately design and monitor in situ microbial remediation techniques for the treatment of subsurface systems contaminated with Cr(VI)."
1231493,Li et al. 2011,"Evaluating the toxicity of environmental concentrations of waterborne chromium (VI) to a model teleost, Oncorhynchus mykiss: a comparative study of in vivo and in vitro","Toxic effects of environmental concentrations (50, 100, and 200?g/L) of waterborne chromium (VI) were evaluated in rainbow trout by comparison of in vitro and in vivo assays. Multiple biomarkers were measured including oxidative stress indices and antioxidant response parameters in liver and brain, as well as Na(+)-K(+)-ATPase in gill. Superoxide dismutase (SOD) and glutathione reductase (GR) activities were significantly induced (1.54-fold and 1.37-fold, respectively) in fish brain in vivo, but no significant differences were observed in any other biomarker or in vivo test group. Oxidative stress was apparent in vitro as significantly higher levels of oxidative indices, with the highest induction of TBARS and CP found in brain at 200?g/L Cr(VI) (2.41-fold and 1.95-fold, respectively), and SOD and GR activities and reduced glutathione in brain were significantly inhibited (65%, 44%, and 36%, respectively). In vitro Na(+)-K(+)-ATPase activity in gill was also significantly inhibited at concentrations of 100 and 200?g/L (69% and 45%, respectively). Short-term exposure to environmental concentrations of Cr(VI) does not therefore evoke marked effects in fish in vivo. Based on the present results, a set of in vitro tests with tissue homogenate can be evoked more remarkable effects by the lower concentrations of Cr(VI) than in vivo, which could provide some useful information and might be a potential alternative approach for monitoring heavy metal pollution in aquatic environments. However, it needs more detailed studies in other area, such as hormonal response or genotoxicity, before these findings could be applied in the field investigation.","Evaluating the toxicity of environmental concentrations of waterborne chromium (VI) to a model teleost, Oncorhynchus mykiss: a comparative study of in vivo and in vitro Abs: Toxic effects of environmental concentrations (50, 100, and 200?g/L) of waterborne chromium (VI) were evaluated in rainbow trout by comparison of in vitro and in vivo assays. Multiple biomarkers were measured including oxidative stress indices and antioxidant response parameters in liver and brain, as well as Na(+)-K(+)-ATPase in gill. Superoxide dismutase (SOD) and glutathione reductase (GR) activities were significantly induced (1.54-fold and 1.37-fold, respectively) in fish brain in vivo, but no significant differences were observed in any other biomarker or in vivo test group. Oxidative stress was apparent in vitro as significantly higher levels of oxidative indices, with the highest induction of TBARS and CP found in brain at 200?g/L Cr(VI) (2.41-fold and 1.95-fold, respectively), and SOD and GR activities and reduced glutathione in brain were significantly inhibited (65%, 44%, and 36%, respectively). In vitro Na(+)-K(+)-ATPase activity in gill was also significantly inhibited at concentrations of 100 and 200?g/L (69% and 45%, respectively). Short-term exposure to environmental concentrations of Cr(VI) does not therefore evoke marked effects in fish in vivo. Based on the present results, a set of in vitro tests with tissue homogenate can be evoked more remarkable effects by the lower concentrations of Cr(VI) than in vivo, which could provide some useful information and might be a potential alternative approach for monitoring heavy metal pollution in aquatic environments. However, it needs more detailed studies in other area, such as hormonal response or genotoxicity, before these findings could be applied in the field investigation."
1231492,Priyantha and  Bandaranayaka 2011,Investigation of kinetics of Cr(VI)-fired brick clay interaction,"Fired brick clay is an excellent sorbent for the removal of heavy metal ions from waste water, owing to the availability of pores and interlayer spacing. Consequently, heat treatment of brick clay significantly affects the extent of interaction between the brick clay sorbent and adsorbates. The interaction between Cr(VI), available as Cr(2)O(7)(2-), and brick clay particles fired at temperatures between 200 °C and 600 °C follows pseudo second order kinetics, and the method of initial rates leads to the estimation of the average rate of the interaction process. Kinetics modeling suggests that the mass transfer of the interaction be mainly controlled by time-dependent intraparticle diffusion, as well as immobilization of Cr(VI) species within interlayer structure of the brick clay matrix and interparticle diffusion, both of which are time-independent.","Investigation of kinetics of Cr(VI)-fired brick clay interaction Abs: Fired brick clay is an excellent sorbent for the removal of heavy metal ions from waste water, owing to the availability of pores and interlayer spacing. Consequently, heat treatment of brick clay significantly affects the extent of interaction between the brick clay sorbent and adsorbates. The interaction between Cr(VI), available as Cr(2)O(7)(2-), and brick clay particles fired at temperatures between 200 °C and 600 °C follows pseudo second order kinetics, and the method of initial rates leads to the estimation of the average rate of the interaction process. Kinetics modeling suggests that the mass transfer of the interaction be mainly controlled by time-dependent intraparticle diffusion, as well as immobilization of Cr(VI) species within interlayer structure of the brick clay matrix and interparticle diffusion, both of which are time-independent."
1231490,Mishra et al. 2011,Tracing the tracks of genotoxicity by trivalent and hexavalent chromium in Drosophila melanogaster,"Mutagen sensitive strains (mus) in Drosophila are known for their hypersensitivity to mutagens and environmental carcinogens. Accordingly, these mutants were grouped in pre- and post-replication repair pathways. However, studying mutants belonging to one particular repair pathway may not be adequate for examining chemical-induced genotoxicity when other repair pathways may neutralize its effect. To test whether both pre-and post-replication pathways are involved and effect of Cr(III)- and Cr(VI)-induced genotoxicity in absence or presence of others, we used double mutant approach in D. melanogaster. We observed DNA damage as evident by changes in Comet assay DNA migration in cells of larvae of Oregon R(+) and single mutants of pre- (mei-9, mus201 and mus210) and post- (mei-41, mus209 and mus309) replication repair pathways and also in double mutants of different combinations (pre-pre, pre-post and post-post replication repair) exposed to increasing concentrations of Cr(VI) (0.0, 5.0, 10.0 and 20.0 ?g/ml) for 48 h. The damage was greater in pre-replication repair mutants after exposure to 5.0 ?g/ml Cr(VI), while effects on Oregon R(+) and post replication repair mutants were insignificant. Post-replication repair mutants revealed significant DNA damage after exposure to 20.0 ?g/ml Cr(VI). Further, double mutants generated in the above repair categories were examined for DNA damage following Cr(VI) exposure and a comparison of damage was studied between single and double mutants. Combinations of double mutants generated in the pre-pre replication repair pathways showed an indifferent interaction between the two mutants after Cr(VI) exposure while a synergistic interaction was evident in exposed post-post replication repair double mutants. Cr(III) (20.0 ?g/ml) exposure to these strains did not induce any significant DNA damage in their cells. The study suggests that both pre- and post-replication pathways are affected in Drosophila by Cr(VI) leading to genotoxicity, which may have consequences for metal-induced carcinogenesis.","Tracing the tracks of genotoxicity by trivalent and hexavalent chromium in Drosophila melanogaster Abs: Mutagen sensitive strains (mus) in Drosophila are known for their hypersensitivity to mutagens and environmental carcinogens. Accordingly, these mutants were grouped in pre- and post-replication repair pathways. However, studying mutants belonging to one particular repair pathway may not be adequate for examining chemical-induced genotoxicity when other repair pathways may neutralize its effect. To test whether both pre-and post-replication pathways are involved and effect of Cr(III)- and Cr(VI)-induced genotoxicity in absence or presence of others, we used double mutant approach in D. melanogaster. We observed DNA damage as evident by changes in Comet assay DNA migration in cells of larvae of Oregon R(+) and single mutants of pre- (mei-9, mus201 and mus210) and post- (mei-41, mus209 and mus309) replication repair pathways and also in double mutants of different combinations (pre-pre, pre-post and post-post replication repair) exposed to increasing concentrations of Cr(VI) (0.0, 5.0, 10.0 and 20.0 ?g/ml) for 48 h. The damage was greater in pre-replication repair mutants after exposure to 5.0 ?g/ml Cr(VI), while effects on Oregon R(+) and post replication repair mutants were insignificant. Post-replication repair mutants revealed significant DNA damage after exposure to 20.0 ?g/ml Cr(VI). Further, double mutants generated in the above repair categories were examined for DNA damage following Cr(VI) exposure and a comparison of damage was studied between single and double mutants. Combinations of double mutants generated in the pre-pre replication repair pathways showed an indifferent interaction between the two mutants after Cr(VI) exposure while a synergistic interaction was evident in exposed post-post replication repair double mutants. Cr(III) (20.0 ?g/ml) exposure to these strains did not induce any significant DNA damage in their cells. The study suggests that both pre- and post-replication pathways are affected in Drosophila by Cr(VI) leading to genotoxicity, which may have consequences for metal-induced carcinogenesis."
1231488,Tsao et al. 2011,"The expression of RKIP, RhoGDI, galectin, c-Myc and p53 in gastrointestinal system of Cr(VI)-exposed rats","Hexavalent chromium (CrVI) is considered to be a risk factor in the formation of human cancer. Raf kinase inhibitor protein (RKIP), Rho-GDI?, galectin, c-Myc and p53 play important roles in cancer formation. The purpose of this study was to determine if Cr(VI) induces the formation of gastrointestinal cancer. We explored the expression of RKIP, Rho-GDI?, galectin, c-Myc and p53 in the colon and stomach in rats exposed to chromium (CrVI). Thirty Wistar rats were divided into six groups which were chronically fed with 250, 500, 750, 1000 and 1250?ppm Na(2) Cr(2) O(7) and water for 60?days. The level of Cr(VI) was determined by electrothermal atomic absorption spectrometry. The expression of RKIP, Rho-GDI?, galectin, c-Myc and p53 of stomach and colon was measured by western blot. The gene expression of RKIP, Rho-GDI?, galectin, c-Myc and p53 of the stomach and colon was determined by RT-PCR. The results showed that the expression of p53 and Rho-GDI? was decreased in the stomach and colon of rats with Cr(VI) treatment. The expression of RKIP was decreased in the stomach and colon of rats treated with high-dose Cr(VI). The expression of c-Myc and gelectin-1 was increased in the stomach and colon of rats with Cr(VI) treatment. We concluded that the anomalous expression of RKIP, Rho-GDI?, galectin, c-Myc and p53 might be a dangerous index of cancer formation in the stomach and colon of rats with Cr(VI) exposure.","The expression of RKIP, RhoGDI, galectin, c-Myc and p53 in gastrointestinal system of Cr(VI)-exposed rats Abs: Hexavalent chromium (CrVI) is considered to be a risk factor in the formation of human cancer. Raf kinase inhibitor protein (RKIP), Rho-GDI?, galectin, c-Myc and p53 play important roles in cancer formation. The purpose of this study was to determine if Cr(VI) induces the formation of gastrointestinal cancer. We explored the expression of RKIP, Rho-GDI?, galectin, c-Myc and p53 in the colon and stomach in rats exposed to chromium (CrVI). Thirty Wistar rats were divided into six groups which were chronically fed with 250, 500, 750, 1000 and 1250?ppm Na(2) Cr(2) O(7) and water for 60?days. The level of Cr(VI) was determined by electrothermal atomic absorption spectrometry. The expression of RKIP, Rho-GDI?, galectin, c-Myc and p53 of stomach and colon was measured by western blot. The gene expression of RKIP, Rho-GDI?, galectin, c-Myc and p53 of the stomach and colon was determined by RT-PCR. The results showed that the expression of p53 and Rho-GDI? was decreased in the stomach and colon of rats with Cr(VI) treatment. The expression of RKIP was decreased in the stomach and colon of rats treated with high-dose Cr(VI). The expression of c-Myc and gelectin-1 was increased in the stomach and colon of rats with Cr(VI) treatment. We concluded that the anomalous expression of RKIP, Rho-GDI?, galectin, c-Myc and p53 might be a dangerous index of cancer formation in the stomach and colon of rats with Cr(VI) exposure."
1231487,Xu et al. 2011,Reduction of hexavalent chromium by Pannonibacter phragmitetus LSSE-09 coated with polyethylenimine-functionalized magnetic nanoparticles under alkaline conditions,"A novel cell separation and immobilization method for Cr (VI)-reduction under alkaline conditions was developed by using superparamagnetic Fe(3)O(4) nanoparticles (NPs). The Fe(3)O(4) NPs were synthesized by coprecipitation followed by modification with sodium citrate and polyethyleneimine (PEI). The surface-modified NPs were monodispersed and the particle size was about 15 nm with a saturation magnetization of 62.3 emu/g and an isoelectric point (pI) of 11.5 at room temperature. PEI-modified Fe(3)O(4) NPs possess positive zeta potential at pH below 11.5, presumable because of the high density of amine groups in the long chains of PEI molecules on the surface. At initial pH 9.0, Pannonibacter phragmitetus LSSE-09 cells were immobilized by PEI-modified NPs via electrostatic attraction and then separated with an external magnetic field. Compared to free cells, the coated cells not only had the same Cr (VI)-reduction activity but could also be easily separated from reaction mixtures by magnetic force. In addition, the magnetically immobilized cells retained high specific Cr (VI)-reduction activity over six batch cycles. The results suggest that the magnetic cell separation technology has potential application for Cr (VI) detoxification in alkaline wastewater.","Reduction of hexavalent chromium by Pannonibacter phragmitetus LSSE-09 coated with polyethylenimine-functionalized magnetic nanoparticles under alkaline conditions Abs: A novel cell separation and immobilization method for Cr (VI)-reduction under alkaline conditions was developed by using superparamagnetic Fe(3)O(4) nanoparticles (NPs). The Fe(3)O(4) NPs were synthesized by coprecipitation followed by modification with sodium citrate and polyethyleneimine (PEI). The surface-modified NPs were monodispersed and the particle size was about 15 nm with a saturation magnetization of 62.3 emu/g and an isoelectric point (pI) of 11.5 at room temperature. PEI-modified Fe(3)O(4) NPs possess positive zeta potential at pH below 11.5, presumable because of the high density of amine groups in the long chains of PEI molecules on the surface. At initial pH 9.0, Pannonibacter phragmitetus LSSE-09 cells were immobilized by PEI-modified NPs via electrostatic attraction and then separated with an external magnetic field. Compared to free cells, the coated cells not only had the same Cr (VI)-reduction activity but could also be easily separated from reaction mixtures by magnetic force. In addition, the magnetically immobilized cells retained high specific Cr (VI)-reduction activity over six batch cycles. The results suggest that the magnetic cell separation technology has potential application for Cr (VI) detoxification in alkaline wastewater."
1231486,Xu et al. 2011,Encapsulation of Pannonibacter phragmitetus LSSE-09 in alginate-carboxymethyl cellulose capsules for reduction of hexavalent chromium under alkaline conditions,"Cr(VI) was efficiently reduced to Cr(III) by Pannonibacter phragmitetus LSSE-09 encapsulated in liquid-core alginate-carboxymethyl cellulose capsules under alkaline conditions. Taking into account the physical properties of the capsules, the activity of encapsulated cells, and total Cr(III) concentration in the supernatant, optimal conditions (0.5% w/v sodium alginate; 2% w/v sodium carboxymethyl cellulose; 0.1 M CaCl?; 30-min gelation time) for LSSE-09 encapsulation were determined. At optimal conditions, a relatively high reduction rate of 4.20 mg g ((dry weight))?¹ min?¹ was obtained. Total Cr(III) concentration in the supernatant was significantly decreased after reduction, because 63.7% of the formed soluble organo-Cr(III) compounds compared with those of free cells were captured by the relatively smaller porous structure of alginate capsules. The optimal pH value (9.0) for Cr(VI) reduction was not changed after encapsulation. In addition, encapsulated LSSE-09 showed no appreciable loss in activity after eight repeated cycles at 37°C, and 85.7% of its initial activity remained after 35-day storage at 4°C. The results suggest that encapsulated LSSE-09 in alginate-carboxymethyl cellulose capsules has potential biotechnological applications for the detoxification of Cr(VI)-contaminated wastewater.","Encapsulation of Pannonibacter phragmitetus LSSE-09 in alginate-carboxymethyl cellulose capsules for reduction of hexavalent chromium under alkaline conditions Abs: Cr(VI) was efficiently reduced to Cr(III) by Pannonibacter phragmitetus LSSE-09 encapsulated in liquid-core alginate-carboxymethyl cellulose capsules under alkaline conditions. Taking into account the physical properties of the capsules, the activity of encapsulated cells, and total Cr(III) concentration in the supernatant, optimal conditions (0.5% w/v sodium alginate; 2% w/v sodium carboxymethyl cellulose; 0.1 M CaCl?; 30-min gelation time) for LSSE-09 encapsulation were determined. At optimal conditions, a relatively high reduction rate of 4.20 mg g ((dry weight))?¹ min?¹ was obtained. Total Cr(III) concentration in the supernatant was significantly decreased after reduction, because 63.7% of the formed soluble organo-Cr(III) compounds compared with those of free cells were captured by the relatively smaller porous structure of alginate capsules. The optimal pH value (9.0) for Cr(VI) reduction was not changed after encapsulation. In addition, encapsulated LSSE-09 showed no appreciable loss in activity after eight repeated cycles at 37°C, and 85.7% of its initial activity remained after 35-day storage at 4°C. The results suggest that encapsulated LSSE-09 in alginate-carboxymethyl cellulose capsules has potential biotechnological applications for the detoxification of Cr(VI)-contaminated wastewater."
1231485,Li Chen et al. 2012,Comparative cytotoxicity and genotoxicity of particulate and soluble hexavalent chromium in human and sperm whale (Physeter macrocephalus) skin cells,"Chromium (Cr) is a global marine pollutant, present in marine mammal tissues. Hexavalent chromium [Cr(VI)] is a known human carcinogen. In this study, we compare the cytotoxic and clastogenic effects of Cr(VI) in human (Homo sapiens) and sperm whale (Physeter macrocephalus) skin fibroblasts. Our data show that increasing concentrations of both particulate and soluble Cr(VI) induce increasing amounts of cytotoxicity and clastogenicity in human and sperm whale skin cells. Furthermore, the data show that sperm whale cells are resistant to these effects exhibiting less cytotoxicity and genotoxicity than the human cells. Differences in Cr uptake accounted for some but not all of the differences in particulate and soluble Cr(VI) genotoxicity, although it did explain the differences in particulate Cr(VI) cytotoxicity. Altogether, the data indicate that Cr(VI) is a genotoxic threat to whales, but also suggest that whales have evolved cellular mechanisms to protect them against the genotoxicity of environmental agents such as Cr(VI).","Comparative cytotoxicity and genotoxicity of particulate and soluble hexavalent chromium in human and sperm whale (Physeter macrocephalus) skin cells Abs: Chromium (Cr) is a global marine pollutant, present in marine mammal tissues. Hexavalent chromium [Cr(VI)] is a known human carcinogen. In this study, we compare the cytotoxic and clastogenic effects of Cr(VI) in human (Homo sapiens) and sperm whale (Physeter macrocephalus) skin fibroblasts. Our data show that increasing concentrations of both particulate and soluble Cr(VI) induce increasing amounts of cytotoxicity and clastogenicity in human and sperm whale skin cells. Furthermore, the data show that sperm whale cells are resistant to these effects exhibiting less cytotoxicity and genotoxicity than the human cells. Differences in Cr uptake accounted for some but not all of the differences in particulate and soluble Cr(VI) genotoxicity, although it did explain the differences in particulate Cr(VI) cytotoxicity. Altogether, the data indicate that Cr(VI) is a genotoxic threat to whales, but also suggest that whales have evolved cellular mechanisms to protect them against the genotoxicity of environmental agents such as Cr(VI)."
1231484,Kimura et al. 2011,Chromium (VI) inhibits mouse metallothionein-I gene transcription by modifying the transcription potential of the co-activator p300,"The production of the heavy metal-binding proteins, the metallothioneins (MTs), is induced by heavy metals such as Zn, Cd, and Hg. MTs maintain Zn homeostasis and attenuate heavy metal-induced cytotoxicity by sequestering these metals and lowering their intracellular concentrations. Previously, we had reported that Zn induced the formation of a co-activator complex containing metal response element-binding transcription factor-1 (MTF-1) and the histone acetyltransferase (HAT), p300, which plays an essential role in the activation of MT-1 transcription. In addition, we had shown that Cr(VI) inhibits Zn-induced MT-1 transcription by preventing the Zn-dependent formation of the MTF-1-p300 complex. In the current study, we have shown that the inhibition by Cr(VI) was partially overcome by the overexpression of p300 or MTF-1 in an MT-I promoter-driven luciferase reporter assay system and have used real-time RT-PCR to determine MT-I mRNA levels. It has been reported that Cr(VI) inhibits CYP1A1 transcription by crosslinking histone deacetylase (HDAC) to the promoter. The crosslink inhibits the recruitment of p300 to the MT-1 promoter and blocks HAT-dependent transactivation by p300. However, our results demonstrate that trichostatin A, an HDAC inhibitor, could not block the inhibitory effects of Cr(VI) on MT-1 transcription and that there were no significant differences in the in vitro inhibitory effects of Cr(VI), Cr(III), and Zn on p300 HAT activity. This suggests that the inhibitory effects of Cr(VI) on MT-I transcription may be due to its effects on the HAT-independent transactivation ability rather than the HAT-dependent, HDAC release-related transactivation ability of p300.","Chromium (VI) inhibits mouse metallothionein-I gene transcription by modifying the transcription potential of the co-activator p300 Abs: The production of the heavy metal-binding proteins, the metallothioneins (MTs), is induced by heavy metals such as Zn, Cd, and Hg. MTs maintain Zn homeostasis and attenuate heavy metal-induced cytotoxicity by sequestering these metals and lowering their intracellular concentrations. Previously, we had reported that Zn induced the formation of a co-activator complex containing metal response element-binding transcription factor-1 (MTF-1) and the histone acetyltransferase (HAT), p300, which plays an essential role in the activation of MT-1 transcription. In addition, we had shown that Cr(VI) inhibits Zn-induced MT-1 transcription by preventing the Zn-dependent formation of the MTF-1-p300 complex. In the current study, we have shown that the inhibition by Cr(VI) was partially overcome by the overexpression of p300 or MTF-1 in an MT-I promoter-driven luciferase reporter assay system and have used real-time RT-PCR to determine MT-I mRNA levels. It has been reported that Cr(VI) inhibits CYP1A1 transcription by crosslinking histone deacetylase (HDAC) to the promoter. The crosslink inhibits the recruitment of p300 to the MT-1 promoter and blocks HAT-dependent transactivation by p300. However, our results demonstrate that trichostatin A, an HDAC inhibitor, could not block the inhibitory effects of Cr(VI) on MT-1 transcription and that there were no significant differences in the in vitro inhibitory effects of Cr(VI), Cr(III), and Zn on p300 HAT activity. This suggests that the inhibitory effects of Cr(VI) on MT-I transcription may be due to its effects on the HAT-independent transactivation ability rather than the HAT-dependent, HDAC release-related transactivation ability of p300."
1231483,Morais et al. 2011,Chromium resistance strategies and toxicity: what makes Ochrobactrum tritici 5bvl1 a strain highly resistant,"Large-scale industrial use of chromium (Cr) resulted in widespread environmental contamination with hexavalent chromium (Cr(VI)). The ability of microorganisms to survive in these environments and detoxify chromate requires the presence of specific resistance systems. Several Cr(VI) resistant species, belonging to a variety of genera, have been isolated in recent years. Ochrobactrum tritici strain 5bvl1 is a model for a highly Cr(VI)-resistant and reducing microorganism, with different strategies to cope with chromium. The strain contains the transposon-located (TnOtChr) chromate resistance genes chrB, chrA, chrC, chrF. The chrB and chrA genes were found to be essential for the establishment of high resistance but not chrC or chrF genes. Other mechanisms involved in chromium resistance in this strain were related to strategies such as specific or unspecific Cr(VI) reduction, free-radical detoxifying activities, and repairing DNA damage. Expression of the chrB, chrC or chrF genes was related to increased resistance to superoxide-generating agents. Genetic analyses also showed that, the ruvB gene is related to chromium resistance in O. tritici 5bvl1. The RuvABC complex probably does not form when ruvB gene is interrupted, and the repair of DNA damage induced by chromium is prevented. Aerobic or anaerobic chromate reductase activity and other unspecific mechanisms for chromium reduction have been identified in different bacteria. In the strain O. tritici 5bvl1, several unspecific mechanisms were found. Dichromate and chromate have different effects on the physiology of the chromium resistant strains and dichromate seems to be more toxic. Toxicity of Cr(VI) was evaluated by following growth, reduction, respiration, glucose uptake assays and by comparing cell morphology.","Chromium resistance strategies and toxicity: what makes Ochrobactrum tritici 5bvl1 a strain highly resistant Abs: Large-scale industrial use of chromium (Cr) resulted in widespread environmental contamination with hexavalent chromium (Cr(VI)). The ability of microorganisms to survive in these environments and detoxify chromate requires the presence of specific resistance systems. Several Cr(VI) resistant species, belonging to a variety of genera, have been isolated in recent years. Ochrobactrum tritici strain 5bvl1 is a model for a highly Cr(VI)-resistant and reducing microorganism, with different strategies to cope with chromium. The strain contains the transposon-located (TnOtChr) chromate resistance genes chrB, chrA, chrC, chrF. The chrB and chrA genes were found to be essential for the establishment of high resistance but not chrC or chrF genes. Other mechanisms involved in chromium resistance in this strain were related to strategies such as specific or unspecific Cr(VI) reduction, free-radical detoxifying activities, and repairing DNA damage. Expression of the chrB, chrC or chrF genes was related to increased resistance to superoxide-generating agents. Genetic analyses also showed that, the ruvB gene is related to chromium resistance in O. tritici 5bvl1. The RuvABC complex probably does not form when ruvB gene is interrupted, and the repair of DNA damage induced by chromium is prevented. Aerobic or anaerobic chromate reductase activity and other unspecific mechanisms for chromium reduction have been identified in different bacteria. In the strain O. tritici 5bvl1, several unspecific mechanisms were found. Dichromate and chromate have different effects on the physiology of the chromium resistant strains and dichromate seems to be more toxic. Toxicity of Cr(VI) was evaluated by following growth, reduction, respiration, glucose uptake assays and by comparing cell morphology."
1231482,Zhang et al. 2011,Chronic occupational exposure to hexavalent chromium causes DNA damage in electroplating workers,"<strong>BACKGROUND: </strong>Occupational exposure to chromium compounds may result in adverse health effects. This study aims to investigate whether low-level hexavalent chromium (Cr(VI)) exposure can cause DNA damage in electroplating workers.<br /><br /><strong>METHODS: </strong>157 electroplating workers and 93 control subjects with no history of occupational exposure to chromium were recruited in Hangzhou, China. Chromium levels in erythrocytes were determined by graphite furnace atomic absorption spectrophotometer. DNA damage in peripheral lymphocytes was evaluated with the alkaline comet assay by three parameters: Olive tail moment, tail length and percent of DNA in the comet tail (tail DNA%). Urinary 8-OHdG levels were measured by ELISA.<br /><br /><strong>RESULTS: </strong>Chromium concentration in erythrocytes was about two times higher in electroplating workers (median: 4.41 ?g/L) than that in control subjects (1.54 ?g/L, P < 0.001). The medians (range) of Olive tail moment, tail length and tail DNA% in exposed workers were 1.13 (0.14-6.77), 11.17 (3.46-52.19) and 3.69 (0.65-16.20), and were significantly higher than those in control subjects (0.14 (0.01-0.39), 3.26 (3.00-4.00) and 0.69 (0.04-2.74), P < 0.001). Urinary 8-OHdG concentration was 13.65 (3.08-66.30) ?g/g creatinine in exposed workers and 8.31 (2.94-30.83) ?g/g creatinine in control subjects (P < 0.001). The differences of urinary 8-OHdG levels, Olive tail moment, tail length and tail DNA% between these two groups remained significant (P < 0.001) even after stratification by potential confounding factors such as age, gender, and smoking status. Chromium exposure was found to be positively associated with chromium levels in erythrocytes, urinary 8-OHdG levels, Olive tail moment, tail length and tail DNA%. Positive dose-response associations were also found between chromium levels in erythrocytes and Olive tail moment, tail length and tail DNA%.<br /><br /><strong>CONCLUSION: </strong>The findings in this study indicated that there was detectable chromium exposure in electroplating workers. Low-level occupational chromium exposure induced DNA damage.","Chronic occupational exposure to hexavalent chromium causes DNA damage in electroplating workers Abs: <strong>BACKGROUND: </strong>Occupational exposure to chromium compounds may result in adverse health effects. This study aims to investigate whether low-level hexavalent chromium (Cr(VI)) exposure can cause DNA damage in electroplating workers.<br /><br /><strong>METHODS: </strong>157 electroplating workers and 93 control subjects with no history of occupational exposure to chromium were recruited in Hangzhou, China. Chromium levels in erythrocytes were determined by graphite furnace atomic absorption spectrophotometer. DNA damage in peripheral lymphocytes was evaluated with the alkaline comet assay by three parameters: Olive tail moment, tail length and percent of DNA in the comet tail (tail DNA%). Urinary 8-OHdG levels were measured by ELISA.<br /><br /><strong>RESULTS: </strong>Chromium concentration in erythrocytes was about two times higher in electroplating workers (median: 4.41 ?g/L) than that in control subjects (1.54 ?g/L, P < 0.001). The medians (range) of Olive tail moment, tail length and tail DNA% in exposed workers were 1.13 (0.14-6.77), 11.17 (3.46-52.19) and 3.69 (0.65-16.20), and were significantly higher than those in control subjects (0.14 (0.01-0.39), 3.26 (3.00-4.00) and 0.69 (0.04-2.74), P < 0.001). Urinary 8-OHdG concentration was 13.65 (3.08-66.30) ?g/g creatinine in exposed workers and 8.31 (2.94-30.83) ?g/g creatinine in control subjects (P < 0.001). The differences of urinary 8-OHdG levels, Olive tail moment, tail length and tail DNA% between these two groups remained significant (P < 0.001) even after stratification by potential confounding factors such as age, gender, and smoking status. Chromium exposure was found to be positively associated with chromium levels in erythrocytes, urinary 8-OHdG levels, Olive tail moment, tail length and tail DNA%. Positive dose-response associations were also found between chromium levels in erythrocytes and Olive tail moment, tail length and tail DNA%.<br /><br /><strong>CONCLUSION: </strong>The findings in this study indicated that there was detectable chromium exposure in electroplating workers. Low-level occupational chromium exposure induced DNA damage."
1231481,Bhaumik et al. 2011,Enhanced removal of Cr(VI) from aqueous solution using polypyrrole/Fe3O4 magnetic nanocomposite,"Fe(3)O(4) coated polypyrrole (PPy) magnetic nanocomposite was prepared via in situ polymerization of pyrrole monomer for the removal of highly toxic Cr(VI). Structure and morphology of the prepared nanocomposite were characterized by attenuated total reflectance Fourier transform infrared spectroscopy (ATR-FTIR), X-ray diffraction pattern, Field emission scanning electron microscopy (FE-SEM) and high resolution transmission electron microscopy (HR-TEM). Electron spin resonance (ESR) studies confirmed that the nanocomposite is magnetic in nature. Up to 100% adsorption was found with 200mg/L Cr(VI) aqueous solution at pH 2. Adsorption of Cr(VI) on the surface of the adsorbent was confirmed by the ATR-FTIR and X-ray photoelectron spectroscopy (XPS). XPS studies also suggested that ion exchange and reduction on the surface of the nanocomposite may be the possible mechanism for Cr(VI) removal by the PPy/Fe(3)O(4) nanocomposite. Adsorption results showed that Cr(VI) removal efficiency by the nanocomposite decreased with an increase in pH. Adsorption kinetics was best described by the pseudo-second-order rate model. Isotherm data fitted well to the Langmuir isotherm model. Thermodynamic study revealed that the adsorption process is endothermic and spontaneous in nature. Desorption experiment showed that in spite of the very poor recovery of the adsorbed Cr(VI); the regenerated adsorbent can be reused successfully for two successive adsorption-desorption cycles without appreciable loss of its original capacity.","Enhanced removal of Cr(VI) from aqueous solution using polypyrrole/Fe3O4 magnetic nanocomposite Abs: Fe(3)O(4) coated polypyrrole (PPy) magnetic nanocomposite was prepared via in situ polymerization of pyrrole monomer for the removal of highly toxic Cr(VI). Structure and morphology of the prepared nanocomposite were characterized by attenuated total reflectance Fourier transform infrared spectroscopy (ATR-FTIR), X-ray diffraction pattern, Field emission scanning electron microscopy (FE-SEM) and high resolution transmission electron microscopy (HR-TEM). Electron spin resonance (ESR) studies confirmed that the nanocomposite is magnetic in nature. Up to 100% adsorption was found with 200mg/L Cr(VI) aqueous solution at pH 2. Adsorption of Cr(VI) on the surface of the adsorbent was confirmed by the ATR-FTIR and X-ray photoelectron spectroscopy (XPS). XPS studies also suggested that ion exchange and reduction on the surface of the nanocomposite may be the possible mechanism for Cr(VI) removal by the PPy/Fe(3)O(4) nanocomposite. Adsorption results showed that Cr(VI) removal efficiency by the nanocomposite decreased with an increase in pH. Adsorption kinetics was best described by the pseudo-second-order rate model. Isotherm data fitted well to the Langmuir isotherm model. Thermodynamic study revealed that the adsorption process is endothermic and spontaneous in nature. Desorption experiment showed that in spite of the very poor recovery of the adsorbed Cr(VI); the regenerated adsorbent can be reused successfully for two successive adsorption-desorption cycles without appreciable loss of its original capacity."
1231478,Contreras et al. 2011,"Biological Cr(VI) removal coupled with biomass growth, biomass decay, and multiple substrate limitation","In this work, a mathematical model for the biological reduction of Cr(VI), carbon and nitrogen sources consumption, and biomass growth under fully aerobic conditions was developed. The model comprises three types of aerobic heterotrophic cells (non-growing cells, growing cells with chromate reductase activity, and growing cells that have lost the chromate reductase activity), and five soluble compounds (organic substrate, ammonia nitrogen, non-metabolizable soluble products, dissolved oxygen, and hexavalent chromium). Two processes are considered responsible for the reduction of Cr(VI). The first one is the reduction of Cr(VI) coupled with growth, the second process is coupled with the endogenous decay of the biomass. The model was calibrated using the results obtained in batch cultures in the absence of carbon and nitrogen sources, using different initial Cr(VI) concentrations (0-100 mgCr L(-1)), two carbon sources (cheese whey and lactose), and different initial nitrogen to carbon ratio (0-50 mgN gCOD(-1)). The calibrated model was used to calculate steady-state values of TSS, soluble COD, TAN and Cr(VI) in continuous systems, obtaining a good agreement with the experimental data. The model also accurately predicted the transient concentration of Cr(VI) as a function of time in response to step changes of the inlet Cr(VI) concentration in continuous systems.","Biological Cr(VI) removal coupled with biomass growth, biomass decay, and multiple substrate limitation Abs: In this work, a mathematical model for the biological reduction of Cr(VI), carbon and nitrogen sources consumption, and biomass growth under fully aerobic conditions was developed. The model comprises three types of aerobic heterotrophic cells (non-growing cells, growing cells with chromate reductase activity, and growing cells that have lost the chromate reductase activity), and five soluble compounds (organic substrate, ammonia nitrogen, non-metabolizable soluble products, dissolved oxygen, and hexavalent chromium). Two processes are considered responsible for the reduction of Cr(VI). The first one is the reduction of Cr(VI) coupled with growth, the second process is coupled with the endogenous decay of the biomass. The model was calibrated using the results obtained in batch cultures in the absence of carbon and nitrogen sources, using different initial Cr(VI) concentrations (0-100 mgCr L(-1)), two carbon sources (cheese whey and lactose), and different initial nitrogen to carbon ratio (0-50 mgN gCOD(-1)). The calibrated model was used to calculate steady-state values of TSS, soluble COD, TAN and Cr(VI) in continuous systems, obtaining a good agreement with the experimental data. The model also accurately predicted the transient concentration of Cr(VI) as a function of time in response to step changes of the inlet Cr(VI) concentration in continuous systems."
1231477,Liu et al. 2011,Enhanced removal of trace Cr(VI) ions from aqueous solution by titanium oxide-Ag composite adsorbents,"Titanium oxide-Ag composite (TOAC) adsorbents were prepared by a facile solution route with Ag nanoparticles being homogeneously dispersed on layered titanium oxide materials. The as-synthesized TOAC exhibited a remarkable capability for trace Cr(VI) removal from an aqueous solution, where the concentration of Cr(VI) could be decreased to a level below 0.05 mg/L within 1h. We have systematically investigated the factors that influenced the adsorption of Cr(VI), for example, the pH value of the solution, and the contact time of TOAC with Cr(VI). We found that the adsorption of Cr(VI) was strongly pH-dependent. The adsorption behavior of Cr(VI) onto TOAC fitted well the Langmuir isotherm and a maximum adsorption capacity of Cr(VI) as 25.7 mg/g was achieved. The adsorption process followed the pseudo-second-order kinetic model, which implied that the adsorption was composed of two steps: the adsorption of Cr(VI) ions onto TOAC followed by the reduction of Cr(VI) to Cr(III) by Ag nanoparticles. Our results revealed that TOAC with high capacity of Cr(VI) removal had promising potential for wastewater treatment.","Enhanced removal of trace Cr(VI) ions from aqueous solution by titanium oxide-Ag composite adsorbents Abs: Titanium oxide-Ag composite (TOAC) adsorbents were prepared by a facile solution route with Ag nanoparticles being homogeneously dispersed on layered titanium oxide materials. The as-synthesized TOAC exhibited a remarkable capability for trace Cr(VI) removal from an aqueous solution, where the concentration of Cr(VI) could be decreased to a level below 0.05 mg/L within 1h. We have systematically investigated the factors that influenced the adsorption of Cr(VI), for example, the pH value of the solution, and the contact time of TOAC with Cr(VI). We found that the adsorption of Cr(VI) was strongly pH-dependent. The adsorption behavior of Cr(VI) onto TOAC fitted well the Langmuir isotherm and a maximum adsorption capacity of Cr(VI) as 25.7 mg/g was achieved. The adsorption process followed the pseudo-second-order kinetic model, which implied that the adsorption was composed of two steps: the adsorption of Cr(VI) ions onto TOAC followed by the reduction of Cr(VI) to Cr(III) by Ag nanoparticles. Our results revealed that TOAC with high capacity of Cr(VI) removal had promising potential for wastewater treatment."
1231476,Huang et al. 2011,Effect of set potential on hexavalent chromium reduction and electricity generation from biocathode microbial fuel cells,"Setting a biocathode potential at -300 mV improved the subsequent performance of an MFC for Cr(VI) reduction compared to a control (no set potential). With this set potential, the startup time was reduced to 19 days, the reduction of Cr(VI) was improved to 19.7 mg/L d, and the maximum power density was increased to 6.4 W/m(3) compared to the control (26 days, 14.0 mg/L d and 4.1 W/m(3)). Set potentials of -150 mV and -300 mV also improved system performance and led to similarly higher utilization of metabolic energy gained (PMEG) than set potentials of +200 mV and -450 mV. We observed putative pili at -150 and -300 mV potentials, and aggregated precipitates on bacterial surfaces in both poised and nonpoised controls. These tests show that there are optimal potentials that can be set for developing a Cr(VI) biocathode.","Effect of set potential on hexavalent chromium reduction and electricity generation from biocathode microbial fuel cells Abs: Setting a biocathode potential at -300 mV improved the subsequent performance of an MFC for Cr(VI) reduction compared to a control (no set potential). With this set potential, the startup time was reduced to 19 days, the reduction of Cr(VI) was improved to 19.7 mg/L d, and the maximum power density was increased to 6.4 W/m(3) compared to the control (26 days, 14.0 mg/L d and 4.1 W/m(3)). Set potentials of -150 mV and -300 mV also improved system performance and led to similarly higher utilization of metabolic energy gained (PMEG) than set potentials of +200 mV and -450 mV. We observed putative pili at -150 and -300 mV potentials, and aggregated precipitates on bacterial surfaces in both poised and nonpoised controls. These tests show that there are optimal potentials that can be set for developing a Cr(VI) biocathode."
1231471,Bala and  Thukral 2011,Phytoremediation of Cr(VI) by Spirodela polyrrhiza (L.) Schleiden employing reducing and chelating agents,"Phytoremediation of Cr(VI) by Spirodela polyrrhiza in binary combinations with low molecular weight organic compounds (LMWOCs) with a reducing or chelating potential, viz., ascorbic acid, citric acid, tartaric acid, oxalic acid, lactic acid, and glycerol was studied in Cr(VI) containing hydroponic media. Significant increase in the relative dry weight of plants with respect to Cr(VI) treated controls was observed with ascorbic acid and glycerol. The uptake of chromium by S. polyrrhiza followed Michaelis-Menten kinetics of active ion uptake. Interaction between Cr and ascorbic acid, oxalic acid, and lactic acid decreased Cr uptake, whereas citric acid, glycerol, and tartaric acid increased it. Supplementation of LMWOCs to Cr(VI) containing media decreased the MDA content of the plants. Multiple regression models revealed that LMWOCs decrease lipid peroxidation independently, as well as that induced by Cr(VI). It was found that superoxide dismutase (SOD), guaiacol peroxidase (GPX), and catalase (CAT) activities were increased significantly in plants growing in media containing Cr(VI). The study established that lactic acid, citric acid, ascorbic acid, and glycerol were most effective in increasing the Cr(VI) phytoremediating potential of S. polyrrhiza and LMWOCs with reducing or chelating properties decrease Cr(VI) stress in S. polyrrhiza.","Phytoremediation of Cr(VI) by Spirodela polyrrhiza (L.) Schleiden employing reducing and chelating agents Abs: Phytoremediation of Cr(VI) by Spirodela polyrrhiza in binary combinations with low molecular weight organic compounds (LMWOCs) with a reducing or chelating potential, viz., ascorbic acid, citric acid, tartaric acid, oxalic acid, lactic acid, and glycerol was studied in Cr(VI) containing hydroponic media. Significant increase in the relative dry weight of plants with respect to Cr(VI) treated controls was observed with ascorbic acid and glycerol. The uptake of chromium by S. polyrrhiza followed Michaelis-Menten kinetics of active ion uptake. Interaction between Cr and ascorbic acid, oxalic acid, and lactic acid decreased Cr uptake, whereas citric acid, glycerol, and tartaric acid increased it. Supplementation of LMWOCs to Cr(VI) containing media decreased the MDA content of the plants. Multiple regression models revealed that LMWOCs decrease lipid peroxidation independently, as well as that induced by Cr(VI). It was found that superoxide dismutase (SOD), guaiacol peroxidase (GPX), and catalase (CAT) activities were increased significantly in plants growing in media containing Cr(VI). The study established that lactic acid, citric acid, ascorbic acid, and glycerol were most effective in increasing the Cr(VI) phytoremediating potential of S. polyrrhiza and LMWOCs with reducing or chelating properties decrease Cr(VI) stress in S. polyrrhiza."
1231470,Linos et al. 2011,Oral ingestion of hexavalent chromium through drinking water and cancer mortality in an industrial area of Greece--an ecological study,"<strong>BACKGROUND: </strong>Hexavalent chromium is a known carcinogen when inhaled, but its carcinogenic potential when orally ingested remains controversial. Water contaminated with hexavalent chromium is a worldwide problem, making this a question of significant public health importance.<br /><br /><strong>METHODS: </strong>We conducted an ecological mortality study within the Oinofita region of Greece, where water has been contaminated with hexavalent chromium. We calculated gender, age, and period standardized mortality ratios (SMRs) for all deaths, cancer deaths, and specific cancer types of Oinofita residents over an 11-year period (1999 - 2009), using the greater prefecture of Voiotia as the standard population.<br /><br /><strong>RESULTS: </strong>A total of 474 deaths were observed. The SMR for all cause mortality was 98 (95% CI 89-107) and for all cancer mortality 114 (95% CI 94-136). The SMR for primary liver cancer was 1104 (95% CI 405-2403, p-value &lt; 0.001). Furthermore, statistically significantly higher SMRs were identified for lung cancer (SMR = 145, 95% CI 100-203, p-value = 0.047) and cancer of the kidney and other genitourinary organs among women (SMR = 368, 95% CI 119-858, p-value = 0.025). Elevated SMRs for several other cancers were also noted (lip, oral cavity and pharynx 344, stomach 121, female breast 134, prostate 128, and leukaemias 168), but these did not reach statistical significance.<br /><br /><strong>CONCLUSIONS: </strong>Elevated cancer mortality in the Oinofita area of Greece supports the hypothesis of hexavalent chromium carcinogenicity via the oral ingestion pathway of exposure. Further studies are needed to determine whether this association is causal, and to establish preventive guidelines and public health recommendations.","Oral ingestion of hexavalent chromium through drinking water and cancer mortality in an industrial area of Greece--an ecological study Abs: <strong>BACKGROUND: </strong>Hexavalent chromium is a known carcinogen when inhaled, but its carcinogenic potential when orally ingested remains controversial. Water contaminated with hexavalent chromium is a worldwide problem, making this a question of significant public health importance.<br /><br /><strong>METHODS: </strong>We conducted an ecological mortality study within the Oinofita region of Greece, where water has been contaminated with hexavalent chromium. We calculated gender, age, and period standardized mortality ratios (SMRs) for all deaths, cancer deaths, and specific cancer types of Oinofita residents over an 11-year period (1999 - 2009), using the greater prefecture of Voiotia as the standard population.<br /><br /><strong>RESULTS: </strong>A total of 474 deaths were observed. The SMR for all cause mortality was 98 (95% CI 89-107) and for all cancer mortality 114 (95% CI 94-136). The SMR for primary liver cancer was 1104 (95% CI 405-2403, p-value &lt; 0.001). Furthermore, statistically significantly higher SMRs were identified for lung cancer (SMR = 145, 95% CI 100-203, p-value = 0.047) and cancer of the kidney and other genitourinary organs among women (SMR = 368, 95% CI 119-858, p-value = 0.025). Elevated SMRs for several other cancers were also noted (lip, oral cavity and pharynx 344, stomach 121, female breast 134, prostate 128, and leukaemias 168), but these did not reach statistical significance.<br /><br /><strong>CONCLUSIONS: </strong>Elevated cancer mortality in the Oinofita area of Greece supports the hypothesis of hexavalent chromium carcinogenicity via the oral ingestion pathway of exposure. Further studies are needed to determine whether this association is causal, and to establish preventive guidelines and public health recommendations."
1231469,Stanley et al. 2011,Chromium-VI arrests cell cycle and decreases granulosa cell proliferation by down-regulating cyclin-dependent kinases (CDK) and cyclins and up-regulating CDK-inhibitors,"Environmental contamination with hexavalent chromium (CrVI) has been increasing in the drinking water of the USA and developing countries. CrVI causes various health problems including menstrual disorders and infertility. Recently, we reported that CrVI causes granulosa cell apoptosis through the intrinsic apoptotic pathway. Our previous studies showed that postnatal exposure to CrVI arrests follicle development. In order to explore the underlying mechanism, primary and immortalized granulosa cells from rats were treated with 10 ?M potassium dichromate and analyses of the cell cycle, and cell cycle regulatory proteins were performed. CrVI decreased cell proliferation as a result of cell cycle arrest and down-regulated cyclin-dependent kinases (CDK), cyclins, and PCNA while up-regulating CDK-inhibitors and down-regulating FSH receptor and ER?. Vitamin C mitigated the effects of CrVI. This study shows that CrVI causes cell cycle arrest in granulosa cells by altering cell cycle regulatory proteins with potential intervention by vitamin C.","Chromium-VI arrests cell cycle and decreases granulosa cell proliferation by down-regulating cyclin-dependent kinases (CDK) and cyclins and up-regulating CDK-inhibitors Abs: Environmental contamination with hexavalent chromium (CrVI) has been increasing in the drinking water of the USA and developing countries. CrVI causes various health problems including menstrual disorders and infertility. Recently, we reported that CrVI causes granulosa cell apoptosis through the intrinsic apoptotic pathway. Our previous studies showed that postnatal exposure to CrVI arrests follicle development. In order to explore the underlying mechanism, primary and immortalized granulosa cells from rats were treated with 10 ?M potassium dichromate and analyses of the cell cycle, and cell cycle regulatory proteins were performed. CrVI decreased cell proliferation as a result of cell cycle arrest and down-regulated cyclin-dependent kinases (CDK), cyclins, and PCNA while up-regulating CDK-inhibitors and down-regulating FSH receptor and ER?. Vitamin C mitigated the effects of CrVI. This study shows that CrVI causes cell cycle arrest in granulosa cells by altering cell cycle regulatory proteins with potential intervention by vitamin C."
1231468,Ravindranath et al. 2011,Raman chemical imaging of chromate reduction sites in a single bacterium using intracellularly grown gold nanoislands,"Imaging live molecular events within micro-organisms at single-cell resolution would deliver valuable mechanistic information much needed in understanding key biological processes. We present a surface-enhanced Raman (SERS) chemical imaging strategy as a first step toward exploring the intracellular bioreduction pockets of toxic chromate in Shewanella. In order to achieve this, we take advantage of an innate reductive mechanism in bacteria of reducing gold ions into intracellular gold nanoislands, which provide the necessary enhancement for SERS imaging. We show that SERS has the sensitivity and selectivity not only to identify but also to differentiate between the two stable valence forms of chromate in cells. The imaging platform was used to understand intracellular metal reduction activities in a ubiquitous metal-reducing organism, Shewanella oneidensis MR-1, by mapping chromate reduction.","Raman chemical imaging of chromate reduction sites in a single bacterium using intracellularly grown gold nanoislands Abs: Imaging live molecular events within micro-organisms at single-cell resolution would deliver valuable mechanistic information much needed in understanding key biological processes. We present a surface-enhanced Raman (SERS) chemical imaging strategy as a first step toward exploring the intracellular bioreduction pockets of toxic chromate in Shewanella. In order to achieve this, we take advantage of an innate reductive mechanism in bacteria of reducing gold ions into intracellular gold nanoislands, which provide the necessary enhancement for SERS imaging. We show that SERS has the sensitivity and selectivity not only to identify but also to differentiate between the two stable valence forms of chromate in cells. The imaging platform was used to understand intracellular metal reduction activities in a ubiquitous metal-reducing organism, Shewanella oneidensis MR-1, by mapping chromate reduction."
1231467,Xia et al. 2011,Chromium(VI) causes down regulation of biotinidase in human bronchial epithelial cells by modifications of histone acetylation,"Hexavalent chromium (Cr(VI)), a commonly used industrial metal, is a well-known mutagen and carcinogen, and occupational exposure can induce a broad spectrum of adverse health effects, including cancers. Although Cr(VI)-induced DNA damage is thought to be the primary mechanism of chromate genotoxicity and mutagenicity, there is an increasing number of reports showing that epigenetic mechanisms of gene regulation might be a central target of Cr(VI) toxicity. Epigenetic changes, such as changes in phosphorylation, altered DNA methylation status, histone acetylation and signaling pathways, have been observed after chromium exposure. Nevertheless, to better demonstrate the roles of epigenetic modifications in Cr(VI)-induced carcinogenesis, more work needs to be carried out. This study is aimed to investigate changes in biotinidase (BTD) and holocarboxylase synthetase (HCS), two major proteins which maintain homeostasis of the newfound epigenetic modification: histone biotinylation, in cells exposed to Cr(VI). The data showed that Cr(VI) decreased BTD expression at the transcriptional level in human bronchial epithelial cells (16HBE). In addition, using the epigenetic modifiers, 5-Aza-2'-deoxycytidine (Aza) and Trichostatin A (TSA), we found that modifications of histone acetylation reversed the inhibition of BTD, suggesting that Cr(VI) may cause down regulation of BTD by modifications of histone acetylation.","Chromium(VI) causes down regulation of biotinidase in human bronchial epithelial cells by modifications of histone acetylation Abs: Hexavalent chromium (Cr(VI)), a commonly used industrial metal, is a well-known mutagen and carcinogen, and occupational exposure can induce a broad spectrum of adverse health effects, including cancers. Although Cr(VI)-induced DNA damage is thought to be the primary mechanism of chromate genotoxicity and mutagenicity, there is an increasing number of reports showing that epigenetic mechanisms of gene regulation might be a central target of Cr(VI) toxicity. Epigenetic changes, such as changes in phosphorylation, altered DNA methylation status, histone acetylation and signaling pathways, have been observed after chromium exposure. Nevertheless, to better demonstrate the roles of epigenetic modifications in Cr(VI)-induced carcinogenesis, more work needs to be carried out. This study is aimed to investigate changes in biotinidase (BTD) and holocarboxylase synthetase (HCS), two major proteins which maintain homeostasis of the newfound epigenetic modification: histone biotinylation, in cells exposed to Cr(VI). The data showed that Cr(VI) decreased BTD expression at the transcriptional level in human bronchial epithelial cells (16HBE). In addition, using the epigenetic modifiers, 5-Aza-2'-deoxycytidine (Aza) and Trichostatin A (TSA), we found that modifications of histone acetylation reversed the inhibition of BTD, suggesting that Cr(VI) may cause down regulation of BTD by modifications of histone acetylation."
1231466,Hu et al. 2011,"Chromium induces chromosomal instability, which is partly due to deregulation of BubR1 and Emi1, two APC/C inhibitors","Disruption of cell cycle checkpoints and interference with the normal cell cycle progression frequently result in cell death or malignant transformation. Hexavalent chromium [Cr(VI)] is a well-known carcinogen that has been implicated in the occurrence of many types of human malignancies, including lung cancer. However, the exact mechanism by which Cr(VI) causes malignant transformation in the lung remains unknown. We have demonstrated that chronic exposure to a non-cytotoxic concentration of Cr(VI) induced a variety of chromosomal abnormalities, including premature sister chromatid separation, chromosomal breakage and the presence of lagging/misaligned chromosomes. After treatment with nocodazole, both HeLa and normal lung bronchial epithelial cells were arrested at mitosis. However, Cr(VI) significantly compromised M-phase arrest induced by nocodazole. Cr(VI) suppressed BubR1 activation and reduced expression of Emi1, leading to an unscheduled activation of APC/C. Consistent with this observation, Cr(VI) treatment caused enhanced polyubiquitination of geminin during mitotic release, while it deregulated the activity of Cdt1, a DNA replication licensing factor. Combined, these results suggest that Cr(VI)-induced chromosomal instability is partly due to a perturbation of APC/C activities, leading to chromosomal instability.","Chromium induces chromosomal instability, which is partly due to deregulation of BubR1 and Emi1, two APC/C inhibitors Abs: Disruption of cell cycle checkpoints and interference with the normal cell cycle progression frequently result in cell death or malignant transformation. Hexavalent chromium [Cr(VI)] is a well-known carcinogen that has been implicated in the occurrence of many types of human malignancies, including lung cancer. However, the exact mechanism by which Cr(VI) causes malignant transformation in the lung remains unknown. We have demonstrated that chronic exposure to a non-cytotoxic concentration of Cr(VI) induced a variety of chromosomal abnormalities, including premature sister chromatid separation, chromosomal breakage and the presence of lagging/misaligned chromosomes. After treatment with nocodazole, both HeLa and normal lung bronchial epithelial cells were arrested at mitosis. However, Cr(VI) significantly compromised M-phase arrest induced by nocodazole. Cr(VI) suppressed BubR1 activation and reduced expression of Emi1, leading to an unscheduled activation of APC/C. Consistent with this observation, Cr(VI) treatment caused enhanced polyubiquitination of geminin during mitotic release, while it deregulated the activity of Cdt1, a DNA replication licensing factor. Combined, these results suggest that Cr(VI)-induced chromosomal instability is partly due to a perturbation of APC/C activities, leading to chromosomal instability."
1231465,Pandey and  Mishra 2011,Organic-inorganic hybrid of chitosan/organoclay bionanocomposites for hexavalent chromium uptake,"Organic-inorganic hybrid of chitosan and nanoclay (Cloisite 10A) was chosen to develop a nanomaterial with combine properties of hydrophilicity of an organic polycation and adsorption capacity of inorganic polyanion. The chitosan/clay nanocomposite (CCN) was prepared by solvent casting method. The material synthesis was found most efficient in adsorbent behavior was studied in detail taking Cr(VI) as representative ion. The chemical, structural and textural characteristics of the material were determined by FTIR, XRD, TEM, SEM and EDAX analysis. XRD and TEM results indicated that an exfoliated structure was formed with addition of small amounts of MMT-Na+(montmorillonite-Na(+)) to the chitosan matrix. These composite material were used for the removal of chromium(VI) from aqueous solution. The conditions for the adsorption by the composite have been optimized and kinetics and thermodynamic studies were performed. Though the adsorption takes place in wide pH range, pH 3 was found most suitable and at this pH the adsorption data were modeled using the Langmuir and Freundlich isotherms at 15 °C and 35 °C, where the data fitted satisfactorily to Langmuir isotherms, the R(2) values being 0.998 and 0.999 respectively indicating unilayer adsorption. Based on Langmuir model, Q(o) was calculated to be 357.14 mg/g. The adsorption showed pseudo second order kinetics with a rate constant of 8.0763 × 10(-4) g mg(-1) min(-1) at 100 ppm Cr(VI) concentration.","Organic-inorganic hybrid of chitosan/organoclay bionanocomposites for hexavalent chromium uptake Abs: Organic-inorganic hybrid of chitosan and nanoclay (Cloisite 10A) was chosen to develop a nanomaterial with combine properties of hydrophilicity of an organic polycation and adsorption capacity of inorganic polyanion. The chitosan/clay nanocomposite (CCN) was prepared by solvent casting method. The material synthesis was found most efficient in adsorbent behavior was studied in detail taking Cr(VI) as representative ion. The chemical, structural and textural characteristics of the material were determined by FTIR, XRD, TEM, SEM and EDAX analysis. XRD and TEM results indicated that an exfoliated structure was formed with addition of small amounts of MMT-Na+(montmorillonite-Na(+)) to the chitosan matrix. These composite material were used for the removal of chromium(VI) from aqueous solution. The conditions for the adsorption by the composite have been optimized and kinetics and thermodynamic studies were performed. Though the adsorption takes place in wide pH range, pH 3 was found most suitable and at this pH the adsorption data were modeled using the Langmuir and Freundlich isotherms at 15 °C and 35 °C, where the data fitted satisfactorily to Langmuir isotherms, the R(2) values being 0.998 and 0.999 respectively indicating unilayer adsorption. Based on Langmuir model, Q(o) was calculated to be 357.14 mg/g. The adsorption showed pseudo second order kinetics with a rate constant of 8.0763 × 10(-4) g mg(-1) min(-1) at 100 ppm Cr(VI) concentration."
1231464,Gambelunghe et al. 2011,Phosphatidylserine metabolism in human lymphoblastic cells exposed to chromium (VI),"<strong>OBJECTIVE: </strong>Hexavalent chromium (Cr(VI)) compounds are widely found in different working environments. These compounds can cause apoptosis in human cells, but the mechanisms underlying chromium-induced apoptosis are not clear. A marker of apoptosis is the exposure of phosphatidylserine on cell membrane and the modification of phosphatidylserine metabolism. The aim of this study was to verify whether chromium could cause phosphatidylserine exposure and modification of its metabolism in human lymphoblastic leukemia cell line (MOLT-4).<br /><br /><strong>METHODS: </strong>Phosphatidylserine exposure was evaluated by annexin V binding whereas phosphatidylserine metabolism was studied measuring the incorporation of [³H]serine.<br /><br /><strong>RESULTS: </strong>Cell treatment with Cr(VI) increases phosphatidylserine exposure and cell apoptosis, but decreases the incorporation of [³H]serine into phosphatidylserine in a dose- and time-dependent manner.<br /><br /><strong>CONCLUSIONS: </strong>The Cr(VI)-induced apoptosis also through modification of phosphatidylserine exposure and metabolism.","Phosphatidylserine metabolism in human lymphoblastic cells exposed to chromium (VI) Abs: <strong>OBJECTIVE: </strong>Hexavalent chromium (Cr(VI)) compounds are widely found in different working environments. These compounds can cause apoptosis in human cells, but the mechanisms underlying chromium-induced apoptosis are not clear. A marker of apoptosis is the exposure of phosphatidylserine on cell membrane and the modification of phosphatidylserine metabolism. The aim of this study was to verify whether chromium could cause phosphatidylserine exposure and modification of its metabolism in human lymphoblastic leukemia cell line (MOLT-4).<br /><br /><strong>METHODS: </strong>Phosphatidylserine exposure was evaluated by annexin V binding whereas phosphatidylserine metabolism was studied measuring the incorporation of [³H]serine.<br /><br /><strong>RESULTS: </strong>Cell treatment with Cr(VI) increases phosphatidylserine exposure and cell apoptosis, but decreases the incorporation of [³H]serine into phosphatidylserine in a dose- and time-dependent manner.<br /><br /><strong>CONCLUSIONS: </strong>The Cr(VI)-induced apoptosis also through modification of phosphatidylserine exposure and metabolism."
1231463,Thompson et al. 2011,Investigation of the mode of action underlying the tumorigenic response induced in B6C3F1 mice exposed orally to hexavalent chromium,"Chronic ingestion of high concentrations of hexavalent chromium [Cr(VI)] in drinking water induces intestinal tumors in mice. To investigate the mode of action (MOA) underlying these tumors, a 90-day drinking water study was conducted using similar exposure conditions as in a previous cancer bioassay, as well as lower (heretofore unexamined) drinking water concentrations. Tissue samples were collected in mice exposed for 7 or 90 days and subjected to histopathological, biochemical, toxicogenomic, and toxicokinetic analyses. Described herein are the results of toxicokinetic, biochemical, and pathological findings. Following 90 days of exposure to 0.3-520 mg/l of sodium dichromate dihydrate (SDD), total chromium concentrations in the duodenum were significantly elevated at ? 14 mg/l. At these concentrations, significant decreases in the reduced-to-oxidized glutathione ratio (GSH/GSSG) were observed. Beginning at 60 mg/l, intestinal lesions were observed including villous cytoplasmic vacuolization. Atrophy, apoptosis, and crypt hyperplasia were evident at ? 170 mg/l. Protein carbonyls were elevated at concentrations ? 4 mg/l SDD, whereas oxidative DNA damage, as assessed by 8-hydroxydeoxyguanosine, was not increased in any treatment group. Significant decreases in the GSH/GSSG ratio and similar histopathological lesions as observed in the duodenum were also observed in the jejunum following 90 days of exposure. Cytokine levels (e.g., interleukin-1?) were generally depressed or unaltered at the termination of the study. Overall, the data suggest that Cr(VI) in drinking water can induce oxidative stress, villous cytotoxicity, and crypt hyperplasia in the mouse intestine and may underlie the MOA of intestinal carcinogenesis in mice.","Investigation of the mode of action underlying the tumorigenic response induced in B6C3F1 mice exposed orally to hexavalent chromium Abs: Chronic ingestion of high concentrations of hexavalent chromium [Cr(VI)] in drinking water induces intestinal tumors in mice. To investigate the mode of action (MOA) underlying these tumors, a 90-day drinking water study was conducted using similar exposure conditions as in a previous cancer bioassay, as well as lower (heretofore unexamined) drinking water concentrations. Tissue samples were collected in mice exposed for 7 or 90 days and subjected to histopathological, biochemical, toxicogenomic, and toxicokinetic analyses. Described herein are the results of toxicokinetic, biochemical, and pathological findings. Following 90 days of exposure to 0.3-520 mg/l of sodium dichromate dihydrate (SDD), total chromium concentrations in the duodenum were significantly elevated at ? 14 mg/l. At these concentrations, significant decreases in the reduced-to-oxidized glutathione ratio (GSH/GSSG) were observed. Beginning at 60 mg/l, intestinal lesions were observed including villous cytoplasmic vacuolization. Atrophy, apoptosis, and crypt hyperplasia were evident at ? 170 mg/l. Protein carbonyls were elevated at concentrations ? 4 mg/l SDD, whereas oxidative DNA damage, as assessed by 8-hydroxydeoxyguanosine, was not increased in any treatment group. Significant decreases in the GSH/GSSG ratio and similar histopathological lesions as observed in the duodenum were also observed in the jejunum following 90 days of exposure. Cytokine levels (e.g., interleukin-1?) were generally depressed or unaltered at the termination of the study. Overall, the data suggest that Cr(VI) in drinking water can induce oxidative stress, villous cytotoxicity, and crypt hyperplasia in the mouse intestine and may underlie the MOA of intestinal carcinogenesis in mice."
1231462,Fan et al. 2011,The synthesis of TiO2 and TiO2-Pt and their application in the removal of Cr (VI),"The deposition of noble metal on titanium dioxide (TiO2) has been considered as an effective strategy to improve the activity of TiO2. In this paper, TiO2 nanoparticles were prepared via a sol-gel route, followed by heat treatment at elevated temperatures. TiO2-Pt catalyst was prepared by deposition of platinum (Pt) on the surface of as-prepared TiO2 nanoparticles. TiO2 and TiO2-Pt were characterized by X-ray diffraction, transmission electron microscopy, Raman spectroscopy, ultraviolet-visible differential reflectance spectra and infrared spectroscopy. TiO2 and TiO2-Pt were used as heterogeneous catalysts for the removal of Cr (VI) under ultraviolet-light illumination. TiO2 prepared at low temperature had smaller particle size and higher specific surface area, and consequently had higher activity on the removal of Cr (VI). The Pt deposited on the surface of TiO2 favoured the separation of photo-produced electrons (e-) and holes (h+), inhibited the recombination of e- and h+, and enhanced Cr (VI) removal. However, its blocking of active sites also inhibited the removal of Cr (VI). The deposition of 1% (wt.%) Pt to TiO2 produced the optimum activity for the removal of Cr (VI). A lower pH favoured the adsorption of Cr (VI) on the surface of TiO2, and correspondingly enhanced the removal of Cr (VI).","The synthesis of TiO2 and TiO2-Pt and their application in the removal of Cr (VI) Abs: The deposition of noble metal on titanium dioxide (TiO2) has been considered as an effective strategy to improve the activity of TiO2. In this paper, TiO2 nanoparticles were prepared via a sol-gel route, followed by heat treatment at elevated temperatures. TiO2-Pt catalyst was prepared by deposition of platinum (Pt) on the surface of as-prepared TiO2 nanoparticles. TiO2 and TiO2-Pt were characterized by X-ray diffraction, transmission electron microscopy, Raman spectroscopy, ultraviolet-visible differential reflectance spectra and infrared spectroscopy. TiO2 and TiO2-Pt were used as heterogeneous catalysts for the removal of Cr (VI) under ultraviolet-light illumination. TiO2 prepared at low temperature had smaller particle size and higher specific surface area, and consequently had higher activity on the removal of Cr (VI). The Pt deposited on the surface of TiO2 favoured the separation of photo-produced electrons (e-) and holes (h+), inhibited the recombination of e- and h+, and enhanced Cr (VI) removal. However, its blocking of active sites also inhibited the removal of Cr (VI). The deposition of 1% (wt.%) Pt to TiO2 produced the optimum activity for the removal of Cr (VI). A lower pH favoured the adsorption of Cr (VI) on the surface of TiO2, and correspondingly enhanced the removal of Cr (VI)."
1231461,Lee and  Lim 2012,Inhibitory effect of SJSZ glycoprotein (38 kDa) on expression of heat shock protein 27 and 70 in chromium (VI)-treated hepatocytes,"Chromium (VI) is as an extremely toxic chemical substance, and is also an internationally recognized human carcinogen. The principal objective of this study was to determine whether or not Styrax japonica Siebold et al. Zuccarini (SJSZ) glycoprotein prevents hepatocarcinogenesis in chromium-treated BNL CL.2 cells and ICR mice. Firstly, it was evaluated that SJSZ glycoprotein has strong antioxidant character and scavenges radicals. In an effort to assess the chemopreventive effects of SJSZ glycoprotein on hepatocarcinogenesis, ICR mice were intraperitoneally injected with chromium (10 mg/kg, BW) for 8 weeks. After sacrifice, we evaluated indicators of liver tissue damage [the activities of lactate dehydrogenase (LDH) and alanine aminotransferase (ALT), and thiobarbituric acid-reactive substances (TBARS)], antioxidative enzymes [activities of superoxide dismutase (SOD), catalase (CAT) and gluthathione peroxidase (GPx)], and initiating hepatocarcinogenic indicator [heat shock protein (HSP) 27 and 70] and protein kinase C (PKC), p38 MAPK and PCNA via biochemical methods and immunoblot analysis. The results obtained from this study demonstrated that the SJSZ glycoprotein (50 ?g/ml) inhibited the production of intracellular ROS in BNL CL.2 cells. In addition, the SJSZ glycoprotein (10 mg/kg, BW) attenuated the levels of LDH, ALT, and TBARS, whereas it increased antioxidative enzymes in mouse serum. SJSZ glycoprotein attenuated the activity of HSP27, HSP70, PKC, MAPKs, and PCNA in BNL CL.2 cells and liver tissue. Taken together, our results indicate that SJSZ glycoprotein might be have a potent preventive effect against hepatocarcinogenesis induced by oxidative stress.","Inhibitory effect of SJSZ glycoprotein (38 kDa) on expression of heat shock protein 27 and 70 in chromium (VI)-treated hepatocytes Abs: Chromium (VI) is as an extremely toxic chemical substance, and is also an internationally recognized human carcinogen. The principal objective of this study was to determine whether or not Styrax japonica Siebold et al. Zuccarini (SJSZ) glycoprotein prevents hepatocarcinogenesis in chromium-treated BNL CL.2 cells and ICR mice. Firstly, it was evaluated that SJSZ glycoprotein has strong antioxidant character and scavenges radicals. In an effort to assess the chemopreventive effects of SJSZ glycoprotein on hepatocarcinogenesis, ICR mice were intraperitoneally injected with chromium (10 mg/kg, BW) for 8 weeks. After sacrifice, we evaluated indicators of liver tissue damage [the activities of lactate dehydrogenase (LDH) and alanine aminotransferase (ALT), and thiobarbituric acid-reactive substances (TBARS)], antioxidative enzymes [activities of superoxide dismutase (SOD), catalase (CAT) and gluthathione peroxidase (GPx)], and initiating hepatocarcinogenic indicator [heat shock protein (HSP) 27 and 70] and protein kinase C (PKC), p38 MAPK and PCNA via biochemical methods and immunoblot analysis. The results obtained from this study demonstrated that the SJSZ glycoprotein (50 ?g/ml) inhibited the production of intracellular ROS in BNL CL.2 cells. In addition, the SJSZ glycoprotein (10 mg/kg, BW) attenuated the levels of LDH, ALT, and TBARS, whereas it increased antioxidative enzymes in mouse serum. SJSZ glycoprotein attenuated the activity of HSP27, HSP70, PKC, MAPKs, and PCNA in BNL CL.2 cells and liver tissue. Taken together, our results indicate that SJSZ glycoprotein might be have a potent preventive effect against hepatocarcinogenesis induced by oxidative stress."
1231459,Wise and  Aboueissab 2011,Addendum to “The cytotoxicity and genotoxicity of hexavalent chromium in Steller sea lion lung fibroblasts compared to human lung fibroblasts” [Comp Biochem Physiol C Toxicol Pharmacol. 152(1)91–8,,Addendum to “The cytotoxicity and genotoxicity of hexavalent chromium in Steller sea lion lung fibroblasts compared to human lung fibroblasts” [Comp Biochem Physiol C Toxicol Pharmacol. 152(1)91–8 Abs: 
1231458,Panda et al. 2011,Removal of hexavalent chromium by biosorption process in rotating packed bed,"Removal of hexavalent chromium ions from an aqueous solution by crude tamarind (Tamarindus indica) fruit shell was examined in a rotating packed bed contactor by continuously recirculating a given volume of solution through the bed. Reduction of Cr(VI) to Cr(III) within the biosorbent appeared to be the removal mechanism. Depletion rate of Cr(VI) from, and release of reduced Cr(III) ions into the aqueous phase, was influenced by mass transfer resistance besides pH and packing depth. A mathematical model considering the reduction reaction to be irreversible and incorporating intraparticle and external phase mass transfer resistances represented the experimental data adequately. The study indicated that the limitations of fixed bed contactor operating under terrestrial gravity in intensifying mass transfer rates for this system can be overcome with rotating packed bed due to liquid flow under centrifugal acceleration.","Removal of hexavalent chromium by biosorption process in rotating packed bed Abs: Removal of hexavalent chromium ions from an aqueous solution by crude tamarind (Tamarindus indica) fruit shell was examined in a rotating packed bed contactor by continuously recirculating a given volume of solution through the bed. Reduction of Cr(VI) to Cr(III) within the biosorbent appeared to be the removal mechanism. Depletion rate of Cr(VI) from, and release of reduced Cr(III) ions into the aqueous phase, was influenced by mass transfer resistance besides pH and packing depth. A mathematical model considering the reduction reaction to be irreversible and incorporating intraparticle and external phase mass transfer resistances represented the experimental data adequately. The study indicated that the limitations of fixed bed contactor operating under terrestrial gravity in intensifying mass transfer rates for this system can be overcome with rotating packed bed due to liquid flow under centrifugal acceleration."
1231457,Molina-Jijón et al. 2011,Curcumin prevents Cr(VI)-induced renal oxidant damage by a mitochondrial pathway,"We report the role of mitochondria in the protective effects of curcumin, a well-known direct and indirect antioxidant, against the renal oxidant damage induced by the hexavalent chromium [Cr(VI)] compound potassium dichromate (K(2)Cr(2)O(7)) in rats. Curcumin was given daily by gavage using three different schemes: (1) complete treatment (100, 200, and 400 mg/kg bw 10 days before and 2 days after K(2)Cr(2)O(7) injection), (2) pretreatment (400 mg/kg bw for 10 days before K(2)Cr(2)O(7) injection), and (3) posttreatment (400 mg/kg bw 2 days after K(2)Cr(2)O(7) injection). Rats were sacrificed 48 h later after a single K(2)Cr(2)O(7) injection (15 mg/kg, sc) to evaluate renal and mitochondrial function and oxidant stress. Curcumin treatment (schemes 1 and 2) attenuated K(2)Cr(2)O(7)-induced renal dysfunction, histological damage, oxidant stress, and the decrease in antioxidant enzyme activity both in kidney tissue and in mitochondria. Curcumin pretreatment attenuated K(2)Cr(2)O(7)-induced mitochondrial dysfunction (alterations in oxygen consumption, ATP content, calcium retention, and mitochondrial membrane potential and decreased activity of complexes I, II, II-III, and V) but was unable to modify renal and mitochondrial Cr(VI) content or to chelate chromium. Curcumin posttreatment was unable to prevent K(2)Cr(2)O(7)-induced renal dysfunction. In further experiments performed in curcumin (400 mg/kg)-pretreated rats it was found that this antioxidant accumulated in kidney and activated Nrf2 at the time when K(2)Cr(2)O(7) was injected, suggesting that both direct and indirect antioxidant effects are involved in the protective effects of curcumin. These findings suggest that the preservation of mitochondrial function plays a key role in the protective effects of curcumin pretreatment against K(2)Cr(2)O(7)-induced renal oxidant damage.","Curcumin prevents Cr(VI)-induced renal oxidant damage by a mitochondrial pathway Abs: We report the role of mitochondria in the protective effects of curcumin, a well-known direct and indirect antioxidant, against the renal oxidant damage induced by the hexavalent chromium [Cr(VI)] compound potassium dichromate (K(2)Cr(2)O(7)) in rats. Curcumin was given daily by gavage using three different schemes: (1) complete treatment (100, 200, and 400 mg/kg bw 10 days before and 2 days after K(2)Cr(2)O(7) injection), (2) pretreatment (400 mg/kg bw for 10 days before K(2)Cr(2)O(7) injection), and (3) posttreatment (400 mg/kg bw 2 days after K(2)Cr(2)O(7) injection). Rats were sacrificed 48 h later after a single K(2)Cr(2)O(7) injection (15 mg/kg, sc) to evaluate renal and mitochondrial function and oxidant stress. Curcumin treatment (schemes 1 and 2) attenuated K(2)Cr(2)O(7)-induced renal dysfunction, histological damage, oxidant stress, and the decrease in antioxidant enzyme activity both in kidney tissue and in mitochondria. Curcumin pretreatment attenuated K(2)Cr(2)O(7)-induced mitochondrial dysfunction (alterations in oxygen consumption, ATP content, calcium retention, and mitochondrial membrane potential and decreased activity of complexes I, II, II-III, and V) but was unable to modify renal and mitochondrial Cr(VI) content or to chelate chromium. Curcumin posttreatment was unable to prevent K(2)Cr(2)O(7)-induced renal dysfunction. In further experiments performed in curcumin (400 mg/kg)-pretreated rats it was found that this antioxidant accumulated in kidney and activated Nrf2 at the time when K(2)Cr(2)O(7) was injected, suggesting that both direct and indirect antioxidant effects are involved in the protective effects of curcumin. These findings suggest that the preservation of mitochondrial function plays a key role in the protective effects of curcumin pretreatment against K(2)Cr(2)O(7)-induced renal oxidant damage."
1231456,Tsuyumoto and  Maruyama 2011,X-ray fluorescence analysis of hexavalent chromium using K? satellite peak observed as counterpart of X-ray absorption near-edge structure pre-edge peak,"A K? satellite peak in X-ray fluorescence (XRF) spectra is observed as a counterpart of the pre-edge peak of the X-ray absorption near edge structure (XANES). In K? emission of chromium, a small satellite peak is observed at 5.983-5.988 keV only for hexavalent chromium compounds such as CrO(3), Na(2)CrO(7)·2H(2)O, Na(2)CrO(4)·4H(2)O, K(2)Cr(2)O(7), K(2)CrO(4), Zn(2)CrO(4)(OH)(2)·2H(2)O, PbCrO(4), and BaCrO(4), together with the main peak at 5.947 keV, while trivalent chromium compounds such as Cr(2)O(3) and Cr(OH)(3)·nH(2)O show only the main peak at 5.947 keV. This corresponds to the fact that the K pre-edge peak in XANES is observed only for the hexavalent chromium compounds. The electronic level causing the satellite peak is almost at the same energy level as that causing the pre-edge peak. Our finding not only affects the interpretation of the origin of the pre-edge peaks but also leads to the simple speciation method of chromium compounds using XRF.","X-ray fluorescence analysis of hexavalent chromium using K? satellite peak observed as counterpart of X-ray absorption near-edge structure pre-edge peak Abs: A K? satellite peak in X-ray fluorescence (XRF) spectra is observed as a counterpart of the pre-edge peak of the X-ray absorption near edge structure (XANES). In K? emission of chromium, a small satellite peak is observed at 5.983-5.988 keV only for hexavalent chromium compounds such as CrO(3), Na(2)CrO(7)·2H(2)O, Na(2)CrO(4)·4H(2)O, K(2)Cr(2)O(7), K(2)CrO(4), Zn(2)CrO(4)(OH)(2)·2H(2)O, PbCrO(4), and BaCrO(4), together with the main peak at 5.947 keV, while trivalent chromium compounds such as Cr(2)O(3) and Cr(OH)(3)·nH(2)O show only the main peak at 5.947 keV. This corresponds to the fact that the K pre-edge peak in XANES is observed only for the hexavalent chromium compounds. The electronic level causing the satellite peak is almost at the same energy level as that causing the pre-edge peak. Our finding not only affects the interpretation of the origin of the pre-edge peaks but also leads to the simple speciation method of chromium compounds using XRF."
1231454,Xu et al. 2011,Recyclable magnetic photocatalysts of Fe2+/TiO2 hierarchical architecture with effective removal of Cr(VI) under UV light from water,"We report the synthesis and photocatalytic removal of Cr(VI) from water of hierarchical micro/nanostructured Fe(2+)/TiO(2) tubes. The TiO(2) tubes fabricated by a facile solvothermal approach show a three-level hierarchical architecture assembled from dense nanosheets nearly vertically standing on the surface of TiO(2) microtube. The nanosheets with a thickness of about 20 nm are composed of numerous TiO(2) nanocrystals with size in the range of 15-20 nm. Ferrous ions are doped into the hierarchical architecture by a reduction route. The Fe(2+)/TiO(2) catalyst demonstrates an effective removal of Cr(VI) from water under UV light and the removal effectiveness reaches 99.3% at the initial Cr(VI) concentration of 10 mg L(-1). The ferrous ion in the catalyst serves not as the photo-electron trap but as an intermedium of a two-step reduction. The TiO(2) photoreduces the Fe(2+) ions to Fe atoms firstly, then the Fe atoms reduce the Cr(VI) to Cr(III), and the later is removed by adsorption. The hierarchical architecture of the catalyst serves as a reactor for the photocatalytic reaction of Cr(VI) ions and an effective absorbent for the removal of Cr(III) ions. The catalyst can be easily magnetically separated from the wastewater after photocatalytic reaction and recycled after acid treatment.","Recyclable magnetic photocatalysts of Fe2+/TiO2 hierarchical architecture with effective removal of Cr(VI) under UV light from water Abs: We report the synthesis and photocatalytic removal of Cr(VI) from water of hierarchical micro/nanostructured Fe(2+)/TiO(2) tubes. The TiO(2) tubes fabricated by a facile solvothermal approach show a three-level hierarchical architecture assembled from dense nanosheets nearly vertically standing on the surface of TiO(2) microtube. The nanosheets with a thickness of about 20 nm are composed of numerous TiO(2) nanocrystals with size in the range of 15-20 nm. Ferrous ions are doped into the hierarchical architecture by a reduction route. The Fe(2+)/TiO(2) catalyst demonstrates an effective removal of Cr(VI) from water under UV light and the removal effectiveness reaches 99.3% at the initial Cr(VI) concentration of 10 mg L(-1). The ferrous ion in the catalyst serves not as the photo-electron trap but as an intermedium of a two-step reduction. The TiO(2) photoreduces the Fe(2+) ions to Fe atoms firstly, then the Fe atoms reduce the Cr(VI) to Cr(III), and the later is removed by adsorption. The hierarchical architecture of the catalyst serves as a reactor for the photocatalytic reaction of Cr(VI) ions and an effective absorbent for the removal of Cr(III) ions. The catalyst can be easily magnetically separated from the wastewater after photocatalytic reaction and recycled after acid treatment."
1231452,Ciacci et al. 2011,Immunomodulation in Mytilus galloprovincialis by non-toxic doses of hexavalent chromium,"In aquatic organisms, the immune function can be affected by exposure to environmental pollutants, including heavy metals. In vertebrate systems, different forms of Cr have been shown induce either immunostimulatory or immunosuppressive processes. Hexavalent Cr, Cr(VI), is an important contaminant released from both domestic and industrial effluents, and the predominant chemical form of the metal in aquatic ecosystems. In this work, the in vitro and in vivo effects of Cr(VI) on immune parameters of the marine bivalve Mytilus galloprovincialis were evaluated. Hemocyte incubation with different concentrations of Cr(VI) (0.1-1-10-100 ?M) induced a dose-dependent decrease in lysosomal membrane stability (LMS). Decreases in extracellular lysozyme release and phagocytic activity were also observed, with stronger effects at lower metal concentrations. On the other hand, in these conditions, Cr(VI) stimulated extracellular superoxide production and nitrite accumulation. The effects of Cr(VI) were also evaluated in mussels exposed to the metal (0.1-1-10 ?g L(-1), corresponding to nanomolar concentrations) for 96 h. Decreases in hemocyte LMS values and in serum lysozyme activity were observed with increasing metal concentrations. Decreased phagocytic activity and increased NO production were recorded, with stronger effects at lower concentrations. In these conditions, decreased Total Hemocyte Counts (THC), but no necrotic/apoptotic processes were observed. Moreover, Cr(VI) at both 0.1 and 1 ?g L(-1) seemed to induce significant changes in transcription of immune genes (lysozyme, Mytilin C, Myticin B, defensin, MgC1q), of the serotonin receptor (5-HTR) and of the stress protein HSP70, whereas that of the anti-apoptotic gene p53 was unaffected. Overall, the results indicate that exposure to non-toxic, environmentally relevant concentrations of Cr(VI) can modulate functional and molecular immune parameters in M. galloprovincialis.","Immunomodulation in Mytilus galloprovincialis by non-toxic doses of hexavalent chromium Abs: In aquatic organisms, the immune function can be affected by exposure to environmental pollutants, including heavy metals. In vertebrate systems, different forms of Cr have been shown induce either immunostimulatory or immunosuppressive processes. Hexavalent Cr, Cr(VI), is an important contaminant released from both domestic and industrial effluents, and the predominant chemical form of the metal in aquatic ecosystems. In this work, the in vitro and in vivo effects of Cr(VI) on immune parameters of the marine bivalve Mytilus galloprovincialis were evaluated. Hemocyte incubation with different concentrations of Cr(VI) (0.1-1-10-100 ?M) induced a dose-dependent decrease in lysosomal membrane stability (LMS). Decreases in extracellular lysozyme release and phagocytic activity were also observed, with stronger effects at lower metal concentrations. On the other hand, in these conditions, Cr(VI) stimulated extracellular superoxide production and nitrite accumulation. The effects of Cr(VI) were also evaluated in mussels exposed to the metal (0.1-1-10 ?g L(-1), corresponding to nanomolar concentrations) for 96 h. Decreases in hemocyte LMS values and in serum lysozyme activity were observed with increasing metal concentrations. Decreased phagocytic activity and increased NO production were recorded, with stronger effects at lower concentrations. In these conditions, decreased Total Hemocyte Counts (THC), but no necrotic/apoptotic processes were observed. Moreover, Cr(VI) at both 0.1 and 1 ?g L(-1) seemed to induce significant changes in transcription of immune genes (lysozyme, Mytilin C, Myticin B, defensin, MgC1q), of the serotonin receptor (5-HTR) and of the stress protein HSP70, whereas that of the anti-apoptotic gene p53 was unaffected. Overall, the results indicate that exposure to non-toxic, environmentally relevant concentrations of Cr(VI) can modulate functional and molecular immune parameters in M. galloprovincialis."
1231451,Gheju and  Balcu 2011,Removal of chromium from Cr(VI) polluted wastewaters by reduction with scrap iron and subsequent precipitation of resulted cations,"This work presents investigations on the total removal of chromium from Cr(VI) aqueous solutions by reduction with scrap iron and subsequent precipitation of the resulted cations with NaOH. The process was detrimentally affected by a compactly passivation film occurred at scrap iron surface, mainly composed of Cr(III) and Fe(III). Maximum removal efficiency of the Cr(total) and Fe(total) achieved in the clarifier under circumneutral and alkaline (pH 9.1) conditions was 98.5% and 100%, respectively. The optimum precipitation pH range which resulted from this study is 7.6-8.0. Fe(total) and Cr(total) were almost entirely removed in the clarifier as Fe(III) and Cr(III) species; however, after Cr(VI) breakthrough in column effluent, chromium was partially removed in the clarifier also as Cr(VI), by coprecipitation with cationic species. As long the column effluent was free of Cr(VI), the average Cr(total) removal efficiency of the packed column and clarifier was 10.8% and 78.8%, respectively. Our results clearly indicated that Cr(VI) contaminated wastewater can be successfully treated by combining reduction with scrap iron and chemical precipitation with NaOH.","Removal of chromium from Cr(VI) polluted wastewaters by reduction with scrap iron and subsequent precipitation of resulted cations Abs: This work presents investigations on the total removal of chromium from Cr(VI) aqueous solutions by reduction with scrap iron and subsequent precipitation of the resulted cations with NaOH. The process was detrimentally affected by a compactly passivation film occurred at scrap iron surface, mainly composed of Cr(III) and Fe(III). Maximum removal efficiency of the Cr(total) and Fe(total) achieved in the clarifier under circumneutral and alkaline (pH 9.1) conditions was 98.5% and 100%, respectively. The optimum precipitation pH range which resulted from this study is 7.6-8.0. Fe(total) and Cr(total) were almost entirely removed in the clarifier as Fe(III) and Cr(III) species; however, after Cr(VI) breakthrough in column effluent, chromium was partially removed in the clarifier also as Cr(VI), by coprecipitation with cationic species. As long the column effluent was free of Cr(VI), the average Cr(total) removal efficiency of the packed column and clarifier was 10.8% and 78.8%, respectively. Our results clearly indicated that Cr(VI) contaminated wastewater can be successfully treated by combining reduction with scrap iron and chemical precipitation with NaOH."
1231450,Kumar et al. 2012,Oxidative stress response and fatty acid changes associated with bioaccumulation of chromium [Cr(VI)] by a fresh water cyanobacterium Chroococcus sp,"Cr(VI) at 2.5, 5, 7.5 and 10 mg/l was removed over 1-5 days by a freshwater cyanobacterium, Chroococcus sp. 2.5 mg Cr(VI)/l gave the optimum rate. With 5 mg Cr(VI)/l, activities of superoxide dismutase and catalase were increased. Amounts of palmitic (16:0), stearic (18:0) and oleic acid (18:1) in the cell also increased after exposure to Cr(VI).","Oxidative stress response and fatty acid changes associated with bioaccumulation of chromium [Cr(VI)] by a fresh water cyanobacterium Chroococcus sp Abs: Cr(VI) at 2.5, 5, 7.5 and 10 mg/l was removed over 1-5 days by a freshwater cyanobacterium, Chroococcus sp. 2.5 mg Cr(VI)/l gave the optimum rate. With 5 mg Cr(VI)/l, activities of superoxide dismutase and catalase were increased. Amounts of palmitic (16:0), stearic (18:0) and oleic acid (18:1) in the cell also increased after exposure to Cr(VI)."
1231449,Thompson et al. 2012,Comparison of the effects of hexavalent chromium in the alimentary canal of F344 rats and B6C3F1 mice following exposure in drinking water: implications for carcinogenic modes of action,"Exposure to high concentrations of hexavalent chromium (Cr[VI]) in drinking water is reported to induce oral mucosa tumors in F344 rats and intestinal tumors in B6C3F1 mice. To investigate the modes of action underlying these tumors, 90-day drinking water studies (with interim necropsy at day 8) were conducted with concentrations of 0.1-182 mg/l Cr(VI), administered as 0.3-520 mg/l sodium dichromate dihydrate. Blood and tissue samples were analyzed for chromium content, oxidative stress, iron levels, and gross and microscopic lesions. Results for the F344 rats are described herein and compared with results from B6C3F1 mice published previously. After 90 days of exposure, total chromium concentrations in the rat and mouse oral mucosae were comparable, yet significant dose-dependent decreases in the reduced-to-oxidized glutathione ratio (GSH/GSSG) were observed only in rats. In the duodenum, changes in GSH/GSSG were only observed in mice. Levels of 8-hydroxydeoxyguanosine were not increased in the oral or duodenal mucosae of either species. Glutathione levels were increased in the duodenum but decreased in the jejunum of both species, indicating potential differential responses in the intestinal segments. Histiocytic infiltration was observed in the duodenum of both species, yet duodenal cytokines were repressed in mice but increased in rats. Serum and bone marrow iron levels were more decreased in rats than mice. Collectively, these data suggest that Cr(VI)-induced carcinogenesis in the rodent alimentary canal involves oxidative stress; however, differences in histopathology, cytokines, and iron status suggest potential contributions from other factors as well.","Comparison of the effects of hexavalent chromium in the alimentary canal of F344 rats and B6C3F1 mice following exposure in drinking water: implications for carcinogenic modes of action Abs: Exposure to high concentrations of hexavalent chromium (Cr[VI]) in drinking water is reported to induce oral mucosa tumors in F344 rats and intestinal tumors in B6C3F1 mice. To investigate the modes of action underlying these tumors, 90-day drinking water studies (with interim necropsy at day 8) were conducted with concentrations of 0.1-182 mg/l Cr(VI), administered as 0.3-520 mg/l sodium dichromate dihydrate. Blood and tissue samples were analyzed for chromium content, oxidative stress, iron levels, and gross and microscopic lesions. Results for the F344 rats are described herein and compared with results from B6C3F1 mice published previously. After 90 days of exposure, total chromium concentrations in the rat and mouse oral mucosae were comparable, yet significant dose-dependent decreases in the reduced-to-oxidized glutathione ratio (GSH/GSSG) were observed only in rats. In the duodenum, changes in GSH/GSSG were only observed in mice. Levels of 8-hydroxydeoxyguanosine were not increased in the oral or duodenal mucosae of either species. Glutathione levels were increased in the duodenum but decreased in the jejunum of both species, indicating potential differential responses in the intestinal segments. Histiocytic infiltration was observed in the duodenum of both species, yet duodenal cytokines were repressed in mice but increased in rats. Serum and bone marrow iron levels were more decreased in rats than mice. Collectively, these data suggest that Cr(VI)-induced carcinogenesis in the rodent alimentary canal involves oxidative stress; however, differences in histopathology, cytokines, and iron status suggest potential contributions from other factors as well."
1231448,Li et al. 2011,Removal of hexavalent chromium in soil and groundwater by supported nano zero-valent iron on silica fume,"Silica fume supported-Fe(0) nanoparticles (SF-Fe(0)) were prepared using commercial silica fume as a support. The feasibility of using this SF-Fe(0) for reductive immobilization of Cr(VI) was investigated through batch tests. Compared with unsupported Fe(0), SF-Fe(0) was significantly more active in Cr(VI) removal especially in 84 wt% silica fume loading. Silica fume had also been found to inhibit the formation of Fe(III)/Cr(III) precipitation on Fe nanoparticles' surface, which was increasing the deactivation resistance of iron. Cr(VI) was removed through physical adsorption of Cr(VI) onto the SF-Fe(0) surface and subsequent reduction of Cr(VI) to Cr(III). The rate of reduction of Cr(VI) could be expressed by pseudo first-order reaction kinetics. The rate constant increased with the increase in iron loading but decreased with the increase in initial Cr(VI) concentration. Furthermore, column tests showed that the SF-Fe(0) could be readily transported in model soil.","Removal of hexavalent chromium in soil and groundwater by supported nano zero-valent iron on silica fume Abs: Silica fume supported-Fe(0) nanoparticles (SF-Fe(0)) were prepared using commercial silica fume as a support. The feasibility of using this SF-Fe(0) for reductive immobilization of Cr(VI) was investigated through batch tests. Compared with unsupported Fe(0), SF-Fe(0) was significantly more active in Cr(VI) removal especially in 84 wt% silica fume loading. Silica fume had also been found to inhibit the formation of Fe(III)/Cr(III) precipitation on Fe nanoparticles' surface, which was increasing the deactivation resistance of iron. Cr(VI) was removed through physical adsorption of Cr(VI) onto the SF-Fe(0) surface and subsequent reduction of Cr(VI) to Cr(III). The rate of reduction of Cr(VI) could be expressed by pseudo first-order reaction kinetics. The rate constant increased with the increase in iron loading but decreased with the increase in initial Cr(VI) concentration. Furthermore, column tests showed that the SF-Fe(0) could be readily transported in model soil."
1231447,Malherbe et al. 2011,Evaluation of hexavalent chromium extraction method EPA method 3060A for soils using XANES spectroscopy,"Hexavalent chromium (Cr(VI)) occurrence in soils is generally determined using an extraction step to transfer it to the liquid phase where it is more easily detected and quantified. In this work, the performance of the most common extraction procedure (EPA Method 3060A) using NaOH-Na(2)CO(3) solutions is evaluated using X-ray absorption near edge structure spectroscopy (XANES), which enables the quantification of Cr(VI) directly in the solid state. Results obtained with both methods were compared for three solid samples with different matrices: a soil containing chromite ore processing residue (COPR), a loamy soil, and a paint sludge. Results showed that Cr(VI) contents determined by the two methods differ significantly, and that the EPA Method 3060A procedure underestimated the Cr(VI) content in all studied samples. The underestimation is particularly pronounced for COPR. Low extraction yield for EPA Method 3060A was found to be the main reason. The Cr(VI) present in COPR was found to be more concentrated in magnetic phases. This work provides new XANES analyses of SRM 2701 and its extraction residues for the purpose of benchmarking EPA 3060A performance.","Evaluation of hexavalent chromium extraction method EPA method 3060A for soils using XANES spectroscopy Abs: Hexavalent chromium (Cr(VI)) occurrence in soils is generally determined using an extraction step to transfer it to the liquid phase where it is more easily detected and quantified. In this work, the performance of the most common extraction procedure (EPA Method 3060A) using NaOH-Na(2)CO(3) solutions is evaluated using X-ray absorption near edge structure spectroscopy (XANES), which enables the quantification of Cr(VI) directly in the solid state. Results obtained with both methods were compared for three solid samples with different matrices: a soil containing chromite ore processing residue (COPR), a loamy soil, and a paint sludge. Results showed that Cr(VI) contents determined by the two methods differ significantly, and that the EPA Method 3060A procedure underestimated the Cr(VI) content in all studied samples. The underestimation is particularly pronounced for COPR. Low extraction yield for EPA Method 3060A was found to be the main reason. The Cr(VI) present in COPR was found to be more concentrated in magnetic phases. This work provides new XANES analyses of SRM 2701 and its extraction residues for the purpose of benchmarking EPA 3060A performance."
1231446,Wu et al. 2012,Epigallocatechin-3-gallate (EGCG) protects against chromate-induced toxicity in vitro,"Hexavalent chromium [Cr(VI)] is a human carcinogen that results in the generation of reactive oxygen species (ROS) and a variety of DNA lesions leading to cell death. Epigallocatechin-3-gallate (EGCG), the major polyphenol present in green tea, possesses potent antioxidative activity capable of protecting normal cells from various stimuli-induced oxidative stress and cell death. Here we demonstrated that co-treatment with EGCG protected human normal bronchial epithelial BEAS-2B cells from Cr(VI)-induced cell death in a dose-dependent manner. Cr(VI) induces apoptosis as the primary mode of cell death. Co-treatment of BEAS-2B cells with EGCG dose-dependently suppressed Cr(VI)-induced apoptosis. Fluorescence microscopic analyses and quantitative measurement revealed that EGCG significantly decreased intracellular levels of ROS induced by Cr(VI) exposure. Using a well-established K(+)/SDS precipitation assay, we further showed that EGCG was able to dose-dependently reduce DNA-protein cross-links (DPC), lesions that could be partially attributed to Cr(VI)-induced oxidative stress. Finally, analyses of Affymetrix microarray containing 28,869 well-annotated genes revealed that, among the 3412 genes changed more than 1.5-fold by Cr(VI) treatment, changes of 2404 genes (70%) were inhibited by pretreatment of EGCG. Real-time PCR confirmed the induction of 3 genes involved in cell death and apoptosis by Cr(VI), which was eliminated by EGCG. In contrast, Cr(VI) reduced the expression of 3 genes related to cellular defense, and this reduction was inhibited by EGCG. Our results indicate that EGCG protects BEAS-2B cells from Cr(VI)-induced cytotoxicity presumably by scavenging ROS and modulating a subset of genes. EGCG, therefore, might serve as a potential chemopreventive agent against Cr(VI) carcinogenesis.","Epigallocatechin-3-gallate (EGCG) protects against chromate-induced toxicity in vitro Abs: Hexavalent chromium [Cr(VI)] is a human carcinogen that results in the generation of reactive oxygen species (ROS) and a variety of DNA lesions leading to cell death. Epigallocatechin-3-gallate (EGCG), the major polyphenol present in green tea, possesses potent antioxidative activity capable of protecting normal cells from various stimuli-induced oxidative stress and cell death. Here we demonstrated that co-treatment with EGCG protected human normal bronchial epithelial BEAS-2B cells from Cr(VI)-induced cell death in a dose-dependent manner. Cr(VI) induces apoptosis as the primary mode of cell death. Co-treatment of BEAS-2B cells with EGCG dose-dependently suppressed Cr(VI)-induced apoptosis. Fluorescence microscopic analyses and quantitative measurement revealed that EGCG significantly decreased intracellular levels of ROS induced by Cr(VI) exposure. Using a well-established K(+)/SDS precipitation assay, we further showed that EGCG was able to dose-dependently reduce DNA-protein cross-links (DPC), lesions that could be partially attributed to Cr(VI)-induced oxidative stress. Finally, analyses of Affymetrix microarray containing 28,869 well-annotated genes revealed that, among the 3412 genes changed more than 1.5-fold by Cr(VI) treatment, changes of 2404 genes (70%) were inhibited by pretreatment of EGCG. Real-time PCR confirmed the induction of 3 genes involved in cell death and apoptosis by Cr(VI), which was eliminated by EGCG. In contrast, Cr(VI) reduced the expression of 3 genes related to cellular defense, and this reduction was inhibited by EGCG. Our results indicate that EGCG protects BEAS-2B cells from Cr(VI)-induced cytotoxicity presumably by scavenging ROS and modulating a subset of genes. EGCG, therefore, might serve as a potential chemopreventive agent against Cr(VI) carcinogenesis."
1231445,Plusquin et al. 2012,Reference genes for qPCR assays in toxic metal and salinity stress in two flatworm model organisms,"The flatworm species Schmidtea mediterranea and Macrostomum lignano have become new and innovative model organisms in stem cell, regeneration and tissue homeostasis research. Because of their unique stem cell system, (lab) technical advantages and their phylogenetic position within the Metazoa, they are also ideal candidate model organisms for toxicity assays. As stress and biomarker screenings are often performed at the transcriptional level, the aim of this study was to establish a set of reference genes for qPCR experiments for these two model organisms in different stress situations. We examined the transcriptional stability of nine potential reference genes (actb, tubb, ck2, cox4, cys, rpl13, gapdh, gm2ap, plscr1) to assess those that are most stable during altered stress conditions (exposure to carcinogenic metals and salinity stress). The gene expression stability was evaluated by means of geNorm and NormFinder algorithms. Sets of best reference genes in these analyses varied between different stress situations, although gm2ap and actb were stably transcribed during all tested combinations. In order to demonstrate the impact of bad normalisation, the stress-specific gene hsp90 was normalised to different sets of reference genes. In contrast to the normalisation according to GeNorm and NormFinder, normalisation of hsp90 in Macrostomum lignano during cadmium stress did not show a significant difference when normalised to only gapdh. On the other hand an increase of variability was noticed when normalised to all nine tested reference genes together. Testing appropriate reference genes is therefore strongly advisable in every new experimental condition.","Reference genes for qPCR assays in toxic metal and salinity stress in two flatworm model organisms Abs: The flatworm species Schmidtea mediterranea and Macrostomum lignano have become new and innovative model organisms in stem cell, regeneration and tissue homeostasis research. Because of their unique stem cell system, (lab) technical advantages and their phylogenetic position within the Metazoa, they are also ideal candidate model organisms for toxicity assays. As stress and biomarker screenings are often performed at the transcriptional level, the aim of this study was to establish a set of reference genes for qPCR experiments for these two model organisms in different stress situations. We examined the transcriptional stability of nine potential reference genes (actb, tubb, ck2, cox4, cys, rpl13, gapdh, gm2ap, plscr1) to assess those that are most stable during altered stress conditions (exposure to carcinogenic metals and salinity stress). The gene expression stability was evaluated by means of geNorm and NormFinder algorithms. Sets of best reference genes in these analyses varied between different stress situations, although gm2ap and actb were stably transcribed during all tested combinations. In order to demonstrate the impact of bad normalisation, the stress-specific gene hsp90 was normalised to different sets of reference genes. In contrast to the normalisation according to GeNorm and NormFinder, normalisation of hsp90 in Macrostomum lignano during cadmium stress did not show a significant difference when normalised to only gapdh. On the other hand an increase of variability was noticed when normalised to all nine tested reference genes together. Testing appropriate reference genes is therefore strongly advisable in every new experimental condition."
1231444,Topham et al. 2012,Control of Cr6+ emissions from gas metal arc welding using a silica precursor as a shielding gas additive,"Hexavalent chromium (Cr(6+)) emitted from welding poses serious health risks to workers exposed to welding fumes. In this study, tetramethylsilane (TMS) was added to shielding gas to control hazardous air pollutants produced during stainless steel welding. The silica precursor acted as an oxidation inhibitor when it decomposed in the high-temperature welding arc, limiting Cr(6+) formation. Additionally, a film of amorphous SiO(2) was deposited on fume particles to insulate them from oxidation. Experiments were conducted following the American Welding Society (AWS) method for fume generation and sampling in an AWS fume hood. The results showed that total shielding gas flow rate impacted the effectiveness of the TMS process. Increasing shielding gas flow rate led to increased reductions in Cr(6+) concentration when TMS was used. When 4.2% of a 30-lpm shielding gas flow was used as TMS carrier gas, Cr(6+) concentration in gas metal arc welding (GMAW) fumes was reduced to below the 2006 Occupational Safety and Health Administration standard (5 ?g m(-3)) and the efficiency was &gt;90%. The process also increased fume particle size from a mode size of 20 nm under baseline conditions to 180-300 nm when TMS was added in all shielding gas flow rates tested. SiO(2) particles formed in the process scavenged nanosized fume particles through intercoagulation. Transmission electron microscopy imagery provided visual evidence of an amorphous film of SiO(2) on some fume particles along with the presence of amorphous SiO(2) agglomerates. These results demonstrate the ability of vapor phase silica precursors to increase welding fume particle size and minimize chromium oxidation, thereby preventing the formation of hexavalent chromium.","Control of Cr6+ emissions from gas metal arc welding using a silica precursor as a shielding gas additive Abs: Hexavalent chromium (Cr(6+)) emitted from welding poses serious health risks to workers exposed to welding fumes. In this study, tetramethylsilane (TMS) was added to shielding gas to control hazardous air pollutants produced during stainless steel welding. The silica precursor acted as an oxidation inhibitor when it decomposed in the high-temperature welding arc, limiting Cr(6+) formation. Additionally, a film of amorphous SiO(2) was deposited on fume particles to insulate them from oxidation. Experiments were conducted following the American Welding Society (AWS) method for fume generation and sampling in an AWS fume hood. The results showed that total shielding gas flow rate impacted the effectiveness of the TMS process. Increasing shielding gas flow rate led to increased reductions in Cr(6+) concentration when TMS was used. When 4.2% of a 30-lpm shielding gas flow was used as TMS carrier gas, Cr(6+) concentration in gas metal arc welding (GMAW) fumes was reduced to below the 2006 Occupational Safety and Health Administration standard (5 ?g m(-3)) and the efficiency was &gt;90%. The process also increased fume particle size from a mode size of 20 nm under baseline conditions to 180-300 nm when TMS was added in all shielding gas flow rates tested. SiO(2) particles formed in the process scavenged nanosized fume particles through intercoagulation. Transmission electron microscopy imagery provided visual evidence of an amorphous film of SiO(2) on some fume particles along with the presence of amorphous SiO(2) agglomerates. These results demonstrate the ability of vapor phase silica precursors to increase welding fume particle size and minimize chromium oxidation, thereby preventing the formation of hexavalent chromium."
1231443,Shen et al. 2012,Removal of hexavalent Cr by coconut coir and derived chars--the effect of surface functionality,"The Cr(VI) removal by coconut coir (CC) and chars obtained at various pyrolysis temperatures were evaluated. Increasing the pyrolysis temperature resulted in an increased surface area of the chars, while the corresponding content of oxygen-containing functional groups of the chars decreased. The Cr(VI) removal by CC and CC-derived chars was primarily attributed to the reduction of Cr(VI) to Cr(III) by the materials and the extent and rate of the Cr(VI) reduction were determined by the oxygen-containing functional groups in the materials. The contribution of pure Cr(VI) adsorption to the overall Cr(VI) removal became relatively significant for the chars obtained at higher temperatures. Accordingly, to develop a cost-effective method for removing Cr(VI) from water, the original CC is more advantageous than the carbonaceous counterparts because no pyrolysis is required for the application and CC has a higher content of functional groups for reducing Cr(VI) to less toxic Cr(III).","Removal of hexavalent Cr by coconut coir and derived chars--the effect of surface functionality Abs: The Cr(VI) removal by coconut coir (CC) and chars obtained at various pyrolysis temperatures were evaluated. Increasing the pyrolysis temperature resulted in an increased surface area of the chars, while the corresponding content of oxygen-containing functional groups of the chars decreased. The Cr(VI) removal by CC and CC-derived chars was primarily attributed to the reduction of Cr(VI) to Cr(III) by the materials and the extent and rate of the Cr(VI) reduction were determined by the oxygen-containing functional groups in the materials. The contribution of pure Cr(VI) adsorption to the overall Cr(VI) removal became relatively significant for the chars obtained at higher temperatures. Accordingly, to develop a cost-effective method for removing Cr(VI) from water, the original CC is more advantageous than the carbonaceous counterparts because no pyrolysis is required for the application and CC has a higher content of functional groups for reducing Cr(VI) to less toxic Cr(III)."
1231442,Ozdener et al. 2011,Effect of hexavalent chromium on the growth and physiological and biochemical parameters on Brassica oleracea L. var. acephala DC,"In order to determine the toxic effect of chromium Cr(VI) on the seed germination, the root and shoot length, the root-cotyledonary leaves, the fresh and dry weight in eight-day-old seedlings Brassica oleracea L. var. acephala DC (kale) were treated with various concentrations of Cr in the growth medium. The accumulation of chromium in the tissues was determined in the cotyledons and the roots of the kale seedlings. High rate of Cr uptake was observed in the roots. But the organs could not accumulate large amount Cr. The effect of Cr on B. oleracea var. acephala was evaluated by changes in chlorophyll a, b, lipid peroxidation, proline, ascorbate, protein carbonyl groups, non-protein thiols and peroxidase activity. There were significant decreases in chlorophylls a, b content of the plants treated with Cr. Chromium treated kale seedlings had higher lipid peroxidation and the protein carbonyl groups in cotyledonary leaves than the roots. The changes refer to toxic effects of Cr. There were increases in the non-protein thiol, the total ascorbate, and proline content in the cotyledons and the roots of the seedlings grown on the media containing 0.1 and 0.15 mM Cr. The guaiacol peroxidase activity was higher in the roots of the seedlings than their cotyledons.","Effect of hexavalent chromium on the growth and physiological and biochemical parameters on Brassica oleracea L. var. acephala DC Abs: In order to determine the toxic effect of chromium Cr(VI) on the seed germination, the root and shoot length, the root-cotyledonary leaves, the fresh and dry weight in eight-day-old seedlings Brassica oleracea L. var. acephala DC (kale) were treated with various concentrations of Cr in the growth medium. The accumulation of chromium in the tissues was determined in the cotyledons and the roots of the kale seedlings. High rate of Cr uptake was observed in the roots. But the organs could not accumulate large amount Cr. The effect of Cr on B. oleracea var. acephala was evaluated by changes in chlorophyll a, b, lipid peroxidation, proline, ascorbate, protein carbonyl groups, non-protein thiols and peroxidase activity. There were significant decreases in chlorophylls a, b content of the plants treated with Cr. Chromium treated kale seedlings had higher lipid peroxidation and the protein carbonyl groups in cotyledonary leaves than the roots. The changes refer to toxic effects of Cr. There were increases in the non-protein thiol, the total ascorbate, and proline content in the cotyledons and the roots of the seedlings grown on the media containing 0.1 and 0.15 mM Cr. The guaiacol peroxidase activity was higher in the roots of the seedlings than their cotyledons."
1231441,Li et al. 2011,Stabilization of Fe(0) nanoparticles with silica fume for enhanced transport and remediation of hexavalent chromium in water and soil,"Effective in situ remediation of Cr(VI) in groundwater requires the successful delivery of reactive iron particles to the subsurface. Fe(0) nanoparticles (20-110 nm diameter) supported on silica fume were synthesized by borohydride reduction of an aqueous iron salt in the presence of a support material. The experimental result showed that attachment of Fe(0) nanoparticles on the commercial available sub-micrometer silica fume prevented them from aggregation while maintaining the particle reactivity. When the Fe(0) concentration was 0.4 g/L, 88.00% of 40 mg/L Cr(VI) was removed by silica fume-supported Fe(0) nanoparticles (SF-Fe(0) in 120 min, 22.55% higher than unsupported Fe(0). Furthermore, transport experiments confirmed that almost all unsupported Fe(0) was retained, whereas 51.50% and 38.29% of SF-Fe(0) were eluted from the vertical and horizontal sand column, respectively. Additionally, the effect of solution ionic strength on the transport ability of SF-Fe(0) was evaluated. The result showed that increase in the salt concentration led to a decrease in the mobility and also the divalent ion Ca2+ had a greater effect than that of monovalent ion Na+.","Stabilization of Fe(0) nanoparticles with silica fume for enhanced transport and remediation of hexavalent chromium in water and soil Abs: Effective in situ remediation of Cr(VI) in groundwater requires the successful delivery of reactive iron particles to the subsurface. Fe(0) nanoparticles (20-110 nm diameter) supported on silica fume were synthesized by borohydride reduction of an aqueous iron salt in the presence of a support material. The experimental result showed that attachment of Fe(0) nanoparticles on the commercial available sub-micrometer silica fume prevented them from aggregation while maintaining the particle reactivity. When the Fe(0) concentration was 0.4 g/L, 88.00% of 40 mg/L Cr(VI) was removed by silica fume-supported Fe(0) nanoparticles (SF-Fe(0) in 120 min, 22.55% higher than unsupported Fe(0). Furthermore, transport experiments confirmed that almost all unsupported Fe(0) was retained, whereas 51.50% and 38.29% of SF-Fe(0) were eluted from the vertical and horizontal sand column, respectively. Additionally, the effect of solution ionic strength on the transport ability of SF-Fe(0) was evaluated. The result showed that increase in the salt concentration led to a decrease in the mobility and also the divalent ion Ca2+ had a greater effect than that of monovalent ion Na+."
1231440,Masood and  Malik 2011,Biosorption of metal ions from aqueous solution and tannery effluent by Bacillus sp. FM1,"The metal binding capacity of Bacillus sp. FM1 isolated from soil irrigated with tannery effluent was assessed using synthetic metal solutions and tannery wastewater. Biosorption of Cr(VI) and Cu(II) ions from aqueous solutions using Bacillus was investigated as a function of pH, initial metal ion concentration and contact time. The optimum adsorption pH value observed for Cr(VI) and Cu(II) ions was 2 and 5, respectively. Metal ion uptake increased with increasing initial metal concentration but no significant difference was observed by increasing the time after 60 min. Maximum uptake capacity of chromium was estimated as 64.102 mg g(-1), and of copper to 78.125 mg g(-1). Equilibrium data were well described by the Langmuir and Freundlich adsorption relations. The presence of functional groups on the cell wall surface of the biomass that may interact with the metal ion was confirmed by Fourier Transform Infrared (FTIR) spectroscopy. The application of Bacillus to remove Cr(VI) and Cu(II) in tannery effluent revealed that the biomass was capable of removing both the metal ions. However, the biosorption performance was slightly lower compared to that of synthetic metal solutions. Several factors may be responsible for this difference. However, the most important factor appears to be the presence of other contaminants such as anions, organics, and other trace metals in the effluent.","Biosorption of metal ions from aqueous solution and tannery effluent by Bacillus sp. FM1 Abs: The metal binding capacity of Bacillus sp. FM1 isolated from soil irrigated with tannery effluent was assessed using synthetic metal solutions and tannery wastewater. Biosorption of Cr(VI) and Cu(II) ions from aqueous solutions using Bacillus was investigated as a function of pH, initial metal ion concentration and contact time. The optimum adsorption pH value observed for Cr(VI) and Cu(II) ions was 2 and 5, respectively. Metal ion uptake increased with increasing initial metal concentration but no significant difference was observed by increasing the time after 60 min. Maximum uptake capacity of chromium was estimated as 64.102 mg g(-1), and of copper to 78.125 mg g(-1). Equilibrium data were well described by the Langmuir and Freundlich adsorption relations. The presence of functional groups on the cell wall surface of the biomass that may interact with the metal ion was confirmed by Fourier Transform Infrared (FTIR) spectroscopy. The application of Bacillus to remove Cr(VI) and Cu(II) in tannery effluent revealed that the biomass was capable of removing both the metal ions. However, the biosorption performance was slightly lower compared to that of synthetic metal solutions. Several factors may be responsible for this difference. However, the most important factor appears to be the presence of other contaminants such as anions, organics, and other trace metals in the effluent."
1231437,Singh et al. 2012,An integrated approach to remove Cr(VI) using immobilized Chlorella minutissima grown in nutrient rich sewage wastewater,"The potential of an integrated system for sewage wastewater treatment and biosorption of chromium(VI) was evaluated using immobilized Chlorella minutissima cells. Immobilized algal cells were grown in sewage wastewater in designed photobioreactor for 48 h and then subjected to removal of Cr(VI) from synthetic wastewater. The effect of pH, Cr(VI) concentration, biosorbent dose on Cr(VI) removal was investigated. C. minutissima showed a higher NH(4)(+)-N and PO(4)(3-)-P removal efficiency (above 99% removal) than the NO(3)(2-)-N (58% removal) in 48 h. Biosorption of Cr(VI) was found to be highly dependent on solution pH, biosorbent dose and initial Cr(VI) concentration. Maximum Cr(VI) uptake 57.33 mg Cr(VI)/g dry biosorbent/L of solution was observed at pH2 with 20% (w/v) biosorbent. Further more than 90% of total Cr adsorbed could be recovered using 0.5 M NaOH as desorption medium.","An integrated approach to remove Cr(VI) using immobilized Chlorella minutissima grown in nutrient rich sewage wastewater Abs: The potential of an integrated system for sewage wastewater treatment and biosorption of chromium(VI) was evaluated using immobilized Chlorella minutissima cells. Immobilized algal cells were grown in sewage wastewater in designed photobioreactor for 48 h and then subjected to removal of Cr(VI) from synthetic wastewater. The effect of pH, Cr(VI) concentration, biosorbent dose on Cr(VI) removal was investigated. C. minutissima showed a higher NH(4)(+)-N and PO(4)(3-)-P removal efficiency (above 99% removal) than the NO(3)(2-)-N (58% removal) in 48 h. Biosorption of Cr(VI) was found to be highly dependent on solution pH, biosorbent dose and initial Cr(VI) concentration. Maximum Cr(VI) uptake 57.33 mg Cr(VI)/g dry biosorbent/L of solution was observed at pH2 with 20% (w/v) biosorbent. Further more than 90% of total Cr adsorbed could be recovered using 0.5 M NaOH as desorption medium."
1231436,Kopec et al. 2012,Genome-wide gene expression effects in B6C3F1 mouse intestinal epithelia following 7 and 90days of exposure to hexavalent chromium in drinking water,"Chronic administration of high doses of hexavalent chromium [Cr(VI)] as sodium dichromate dihydrate (SDD) elicits alimentary cancers in mice. To further elucidate key events underlying tumor formation, a 90-day drinking water study was conducted in B6C3F1 mice. Differential gene expression was examined in duodenal and jejunal epithelial samples following 7 or 90days of exposure to 0, 0.3, 4, 14, 60, 170 or 520mg/L SDD in drinking water. Genome-wide microarray analyses identified 6562 duodenal and 4448 jejunal unique differentially expressed genes at day 8, and 4630 and 4845 unique changes, respectively, in the duodenum and jejunum at day 91. Comparative analysis identified significant overlap in duodenal and jejunal differential gene expression. Automated dose-response modeling identified &gt;80% of the differentially expressed genes exhibited sigmoidal dose-response curves with EC(50) values ranging from 10 to 100mg/L SDD. Only 16 genes satisfying the dose-dependent differential expression criteria had EC(50) values &lt;10mg/L SDD, 3 of which were regulated by Nrf2, suggesting oxidative stress in response to SDD at low concentrations. Analyses of differentially expressed genes identified over-represented functions associated with oxidative stress, cell cycle, lipid metabolism, and immune responses consistent with the reported effects on redox status and histopathology at corresponding SDD drinking water concentrations. Collectively, these data are consistent with a mode of action involving oxidative stress and cytotoxicity as early key events. This suggests that the tumorigenic effects of chronic Cr(VI) oral exposure likely require chronic tissue damage and compensatory epithelial cell proliferation.","Genome-wide gene expression effects in B6C3F1 mouse intestinal epithelia following 7 and 90days of exposure to hexavalent chromium in drinking water Abs: Chronic administration of high doses of hexavalent chromium [Cr(VI)] as sodium dichromate dihydrate (SDD) elicits alimentary cancers in mice. To further elucidate key events underlying tumor formation, a 90-day drinking water study was conducted in B6C3F1 mice. Differential gene expression was examined in duodenal and jejunal epithelial samples following 7 or 90days of exposure to 0, 0.3, 4, 14, 60, 170 or 520mg/L SDD in drinking water. Genome-wide microarray analyses identified 6562 duodenal and 4448 jejunal unique differentially expressed genes at day 8, and 4630 and 4845 unique changes, respectively, in the duodenum and jejunum at day 91. Comparative analysis identified significant overlap in duodenal and jejunal differential gene expression. Automated dose-response modeling identified &gt;80% of the differentially expressed genes exhibited sigmoidal dose-response curves with EC(50) values ranging from 10 to 100mg/L SDD. Only 16 genes satisfying the dose-dependent differential expression criteria had EC(50) values &lt;10mg/L SDD, 3 of which were regulated by Nrf2, suggesting oxidative stress in response to SDD at low concentrations. Analyses of differentially expressed genes identified over-represented functions associated with oxidative stress, cell cycle, lipid metabolism, and immune responses consistent with the reported effects on redox status and histopathology at corresponding SDD drinking water concentrations. Collectively, these data are consistent with a mode of action involving oxidative stress and cytotoxicity as early key events. This suggests that the tumorigenic effects of chronic Cr(VI) oral exposure likely require chronic tissue damage and compensatory epithelial cell proliferation."
1231435,Xu et al. 2012,In vitro reduction of hexavalent chromium by cytoplasmic fractions of Pannonibacter phragmitetus LSSE-09 under aerobic and anaerobic conditions,"Hexavalent chromate reductase was characterized and was found to be localized in the cytoplasmic fraction of a chromium-resistant bacterium Pannonibacter phragmitetus LSSE-09. The Cr(VI) reductase activity of cell-free extract (S??) was significantly improved by external electron donors, such as NADH, glucose, acetate, formate, citrate, pyruvate, and lactate. The reductase activity was optimal at pH 7.0 with NADH as the electron donor. The aerobic and anaerobic Cr(VI)-reduction enhanced by 0.1 mM NADH were respectively 3.5 and 3.4 times as high as that without adding NADH. The Cr(VI) reductase activity was inhibited by Mn²?, Cd²?, Fe³?, and Hg²?, whereas Cu²? enhanced the chromate reductase activity by 29% aerobically and 33% anaerobically. The aerobic and anaerobic specific Michaelis-Menten constant K(m) of S?? fraction was estimated to be 64.95 and 47.65 ?mol L?¹, respectively. The soluble S??? fractions showed similar activity to S?? and could reduce 39.7% and 53.4% of Cr(VI) after 1 h of incubation aerobically and anaerobically while the periplasmic contents showed no obvious reduction activity, suggesting an effective enzymatic mechanism of Cr(VI) reduction in the cytoplasmic fractions of the bacterium. Results suggest that the enzymatic reduction of Cr(VI) could be useful for Cr(VI) detoxification in wastewater.","In vitro reduction of hexavalent chromium by cytoplasmic fractions of Pannonibacter phragmitetus LSSE-09 under aerobic and anaerobic conditions Abs: Hexavalent chromate reductase was characterized and was found to be localized in the cytoplasmic fraction of a chromium-resistant bacterium Pannonibacter phragmitetus LSSE-09. The Cr(VI) reductase activity of cell-free extract (S??) was significantly improved by external electron donors, such as NADH, glucose, acetate, formate, citrate, pyruvate, and lactate. The reductase activity was optimal at pH 7.0 with NADH as the electron donor. The aerobic and anaerobic Cr(VI)-reduction enhanced by 0.1 mM NADH were respectively 3.5 and 3.4 times as high as that without adding NADH. The Cr(VI) reductase activity was inhibited by Mn²?, Cd²?, Fe³?, and Hg²?, whereas Cu²? enhanced the chromate reductase activity by 29% aerobically and 33% anaerobically. The aerobic and anaerobic specific Michaelis-Menten constant K(m) of S?? fraction was estimated to be 64.95 and 47.65 ?mol L?¹, respectively. The soluble S??? fractions showed similar activity to S?? and could reduce 39.7% and 53.4% of Cr(VI) after 1 h of incubation aerobically and anaerobically while the periplasmic contents showed no obvious reduction activity, suggesting an effective enzymatic mechanism of Cr(VI) reduction in the cytoplasmic fractions of the bacterium. Results suggest that the enzymatic reduction of Cr(VI) could be useful for Cr(VI) detoxification in wastewater."
1231434,Chrysochoou et al. 2012,A comparative evaluation of hexavalent chromium treatment in contaminated soil by calcium polysulfide and green-tea nanoscale zero-valent iron,"A column study for hexavalent chromium (Cr(VI)) removal from contaminated soil was performed using calcium polysulfide (CPS) and nanoscale zero-valent iron stabilized with green tea extract (GT-nZVI). Injection of CPS at 12 times the stoichiometric requirement (12×) resulted in quantitative Cr(VI) removal for up to 195 days of equivalent groundwater flow. Solid-bound Cr(VI) was reduced up to &gt;99% (&lt;2mg/kg). Treatment with CPS resulted in a short-term release of high sulfur concentrations. Injections of 12× and 24× stoichiometric GT-nZVI resulted in decrease in leachate pH from 6 to 2.5, which rebounded to 4.5 after the equivalent of 45 days and remained stable for the next equivalent 3 years. Metals concentrations in the effluent (Pb, Cr and Fe) increased following injection and quickly decreased, such that the mass flux was low with respect to the total amounts in the solid. Aqueous Cr(VI) was non-detect for the majority of the monitoring time, but concentrations eventually increased with respect to the control sample. Solid-bound Cr(VI) concentrations decreased by 30% and 66% in the 12× and 24× treatments, respectively. The low efficiency was attributed to increased sorption to iron surfaces at pH 2.5 and slow dissolution of PbCrO4, both of which were identified by micro-X-ray fluorescence and absorption analyses.","A comparative evaluation of hexavalent chromium treatment in contaminated soil by calcium polysulfide and green-tea nanoscale zero-valent iron Abs: A column study for hexavalent chromium (Cr(VI)) removal from contaminated soil was performed using calcium polysulfide (CPS) and nanoscale zero-valent iron stabilized with green tea extract (GT-nZVI). Injection of CPS at 12 times the stoichiometric requirement (12×) resulted in quantitative Cr(VI) removal for up to 195 days of equivalent groundwater flow. Solid-bound Cr(VI) was reduced up to &gt;99% (&lt;2mg/kg). Treatment with CPS resulted in a short-term release of high sulfur concentrations. Injections of 12× and 24× stoichiometric GT-nZVI resulted in decrease in leachate pH from 6 to 2.5, which rebounded to 4.5 after the equivalent of 45 days and remained stable for the next equivalent 3 years. Metals concentrations in the effluent (Pb, Cr and Fe) increased following injection and quickly decreased, such that the mass flux was low with respect to the total amounts in the solid. Aqueous Cr(VI) was non-detect for the majority of the monitoring time, but concentrations eventually increased with respect to the control sample. Solid-bound Cr(VI) concentrations decreased by 30% and 66% in the 12× and 24× treatments, respectively. The low efficiency was attributed to increased sorption to iron surfaces at pH 2.5 and slow dissolution of PbCrO4, both of which were identified by micro-X-ray fluorescence and absorption analyses."
1231433,Sagar et al. 2012,Hexavalent chromium reduction and plant growth promotion by Staphylococcusarlettae strain Cr11,"Cr(VI), a mutagenic and carcinogenic pollutant in industrial effluents, was effectively reduced by an indigenous tannery effluent isolate Staphylococcus arlettae strain Cr11 under aerobic conditions. The isolate could tolerate Cr(VI) up to 2000 and 5000 mg L(-1) in liquid and solid media respectively. S. arlettae Cr11 effectively reduced 98% of 100 mg L(-1) Cr(VI) in 24h. Reduction for initial Cr(VI) concentrations of 500 and 1000 mg L(-1) was 98% and 75%, respectively in 120 h. The isolate was also positive for siderophore, indole acetic acid, ammonia and catalase production, phosphate solubilization and biofilm formation in the presence and absence of Cr(VI). The isolate showed halotolerance (10% NaCl) and cross tolerance to other toxic heavy metals such as Hg(2+), Ni(2+), Cd(2+) and Pb(2+). Bacterial inoculation of Triticum aestivum in controlled petri dish and soil environment showed significant increase in percent germination, root and shoot length as well as dry and wet weight in Cr(VI) treated and untreated samples. This is the first report of simultaneous Cr(VI) reduction and plant growth promotion for a S. arlettae strain.","Hexavalent chromium reduction and plant growth promotion by Staphylococcusarlettae strain Cr11 Abs: Cr(VI), a mutagenic and carcinogenic pollutant in industrial effluents, was effectively reduced by an indigenous tannery effluent isolate Staphylococcus arlettae strain Cr11 under aerobic conditions. The isolate could tolerate Cr(VI) up to 2000 and 5000 mg L(-1) in liquid and solid media respectively. S. arlettae Cr11 effectively reduced 98% of 100 mg L(-1) Cr(VI) in 24h. Reduction for initial Cr(VI) concentrations of 500 and 1000 mg L(-1) was 98% and 75%, respectively in 120 h. The isolate was also positive for siderophore, indole acetic acid, ammonia and catalase production, phosphate solubilization and biofilm formation in the presence and absence of Cr(VI). The isolate showed halotolerance (10% NaCl) and cross tolerance to other toxic heavy metals such as Hg(2+), Ni(2+), Cd(2+) and Pb(2+). Bacterial inoculation of Triticum aestivum in controlled petri dish and soil environment showed significant increase in percent germination, root and shoot length as well as dry and wet weight in Cr(VI) treated and untreated samples. This is the first report of simultaneous Cr(VI) reduction and plant growth promotion for a S. arlettae strain."
1231430,Chen et al. 2012,Simultaneous determination of Cr(III) and Cr(VI) in tannery wastewater using low pressure ion chromatography combined with flow injection spectrophotometry,"Trivalent and hexavalent chromium have been successfully separated and determined using low pressure ion chromatography combined with flow injection spectrophotometric analysis (LPIC-FIA). A column packed with crosslinking starch microspheres was used for on-line separation of Cr(III) from Cr(VI) in a flow-injection system because of its absorptive effect on Cr(III). To determine the concentration of Cr(III) and Cr(VI) in samples, we used 3.0 mmol/L nitric acid to elute adsorbed Cr(III) from the column and then used ceric sulfate-sulfuric acid as oxidant to convert all Cr(III) into Cr(VI). Then, Cr(VI) directly came from the samples and Cr(VI) came from Cr(III) successively formed a amaranthine complex with diphenycarbazide and the complex shows a maximum absorption at 530 nm. Analytical parameters including the concentration of eluent and oxidant solution, oxidizing temperature, length of oxidizing reaction coil, reaction coil and injection coil, interfering effects, etc., were optimized. The limit of detection was 1.25 ?g/L for Cr(VI) and 3.76 ?g/L for Cr(III). The linear relationship between absorption with the concentration of Cr(VI) and Cr(III) was 0.001-1.000 mg/L and 0.030-1.000 mg/L with correlation coefficients of 0.9995 and 0.9994, respectively. The relative standard deviation of Cr(VI) and Cr(III) was 1.21% and 1.66%, respectively (n=10). Major cations and anions did not show any interference. We validated this method through certified reference materials and through measuring the recovery in tannery wastewater.","Simultaneous determination of Cr(III) and Cr(VI) in tannery wastewater using low pressure ion chromatography combined with flow injection spectrophotometry Abs: Trivalent and hexavalent chromium have been successfully separated and determined using low pressure ion chromatography combined with flow injection spectrophotometric analysis (LPIC-FIA). A column packed with crosslinking starch microspheres was used for on-line separation of Cr(III) from Cr(VI) in a flow-injection system because of its absorptive effect on Cr(III). To determine the concentration of Cr(III) and Cr(VI) in samples, we used 3.0 mmol/L nitric acid to elute adsorbed Cr(III) from the column and then used ceric sulfate-sulfuric acid as oxidant to convert all Cr(III) into Cr(VI). Then, Cr(VI) directly came from the samples and Cr(VI) came from Cr(III) successively formed a amaranthine complex with diphenycarbazide and the complex shows a maximum absorption at 530 nm. Analytical parameters including the concentration of eluent and oxidant solution, oxidizing temperature, length of oxidizing reaction coil, reaction coil and injection coil, interfering effects, etc., were optimized. The limit of detection was 1.25 ?g/L for Cr(VI) and 3.76 ?g/L for Cr(III). The linear relationship between absorption with the concentration of Cr(VI) and Cr(III) was 0.001-1.000 mg/L and 0.030-1.000 mg/L with correlation coefficients of 0.9995 and 0.9994, respectively. The relative standard deviation of Cr(VI) and Cr(III) was 1.21% and 1.66%, respectively (n=10). Major cations and anions did not show any interference. We validated this method through certified reference materials and through measuring the recovery in tannery wastewater."
1231429,Arzate-Cárdenas and  Martínez-Jerónimo 2012,Energy resource reallocation in Daphnia schodleri (Anomopoda: Daphniidae) reproduction induced by exposure to hexavalent chromium,"Cladocerans are able to store energy in the form of macromolecules such as proteins, lipids and carbohydrates. However, their ability to do so depends to a large extent on their physiological and reproductive condition as well as their age. These macromolecules constitute the total caloric reserves of the body and may be modified as a result of environmental stress conditions by either physical or nutritional factors or by exposure to toxic compounds. Neonates of the freshwater cladoceran Daphnia schodleri were exposed to 0.0064, 0.032 and 0.064 mg L(-1) of hexavalent chromium - Cr(VI) - up to age 5, 7, 14, 21 or 28 d. Survival and fecundity of parthenogenetic females was evaluated for 28d (maximum exposure period). Body length and maximum width were determined in specimens of all ages. Caloric content was evaluated in progeny and females within each age group. Female survival was significantly lower with exposure to 0.064 mg L(-1) of Cr(VI) than with other treatments, and negative effects on reproduction were observed from the lowest concentration on. Largest adult size was attained by control specimens towards the end of the observation period, but no significant differences in neonate size occurred between concentrations. Energy content decreased in adults as toxicant concentration increased, but these females allocated a larger amount of energy reserves to their progeny as a possible compensation aimed at ensuring neonate survival in an adverse environment due to toxicant presence. Sublethal concentrations of Cr(VI) modified energy content in D. schodleri, affecting to varying degrees its survival, growth and reproduction.","Energy resource reallocation in Daphnia schodleri (Anomopoda: Daphniidae) reproduction induced by exposure to hexavalent chromium Abs: Cladocerans are able to store energy in the form of macromolecules such as proteins, lipids and carbohydrates. However, their ability to do so depends to a large extent on their physiological and reproductive condition as well as their age. These macromolecules constitute the total caloric reserves of the body and may be modified as a result of environmental stress conditions by either physical or nutritional factors or by exposure to toxic compounds. Neonates of the freshwater cladoceran Daphnia schodleri were exposed to 0.0064, 0.032 and 0.064 mg L(-1) of hexavalent chromium - Cr(VI) - up to age 5, 7, 14, 21 or 28 d. Survival and fecundity of parthenogenetic females was evaluated for 28d (maximum exposure period). Body length and maximum width were determined in specimens of all ages. Caloric content was evaluated in progeny and females within each age group. Female survival was significantly lower with exposure to 0.064 mg L(-1) of Cr(VI) than with other treatments, and negative effects on reproduction were observed from the lowest concentration on. Largest adult size was attained by control specimens towards the end of the observation period, but no significant differences in neonate size occurred between concentrations. Energy content decreased in adults as toxicant concentration increased, but these females allocated a larger amount of energy reserves to their progeny as a possible compensation aimed at ensuring neonate survival in an adverse environment due to toxicant presence. Sublethal concentrations of Cr(VI) modified energy content in D. schodleri, affecting to varying degrees its survival, growth and reproduction."
1231428,Panda and  Sarkar 2012,Isolation and identification of chromium-resistant bacteria: Test application for prevention of chromium toxicity in plant,"The purpose of this study was to isolate chromium resistant bacteria and characterize in depth before being applied for bioremediation or construction of chromium biosesnors. One of the major objectives was to identify the most useful strains with respect to chromium removal efficiency. Chromium resistant bacteria were isolated from tannery waste samples. These were characterized through biochemical tests and antibiotic assays. Cross metal reactivity, plasmid curing and cysteine quantifications were also performed. Gene sequencing was done for all the isolates and accession numbers received after submission to National Center for Biotechnology Information (NCBI). The removal capacity was also studied in broth cultures. The results were very encouraging since six new bacteria were recognised to withstand high concentrations of chromium. Out of these six bacteria, three i.e. Enterobacter aerogenes, Aeromonas sp., Acinetobacter sp. PD 12 performed very well by removing about 99% (average) from initial 19.8 ppm of Cr(VI) from a synthetic culture media. Enterobacter aerogenes, being the most efficient strain, was used to remediate hexavalent chromium from soil of potted plants- very encouraging results were obtained. These bacteria may be exploited for bioremediation of Cr (VI) and construction of microbial sensor in future.","Isolation and identification of chromium-resistant bacteria: Test application for prevention of chromium toxicity in plant Abs: The purpose of this study was to isolate chromium resistant bacteria and characterize in depth before being applied for bioremediation or construction of chromium biosesnors. One of the major objectives was to identify the most useful strains with respect to chromium removal efficiency. Chromium resistant bacteria were isolated from tannery waste samples. These were characterized through biochemical tests and antibiotic assays. Cross metal reactivity, plasmid curing and cysteine quantifications were also performed. Gene sequencing was done for all the isolates and accession numbers received after submission to National Center for Biotechnology Information (NCBI). The removal capacity was also studied in broth cultures. The results were very encouraging since six new bacteria were recognised to withstand high concentrations of chromium. Out of these six bacteria, three i.e. Enterobacter aerogenes, Aeromonas sp., Acinetobacter sp. PD 12 performed very well by removing about 99% (average) from initial 19.8 ppm of Cr(VI) from a synthetic culture media. Enterobacter aerogenes, being the most efficient strain, was used to remediate hexavalent chromium from soil of potted plants- very encouraging results were obtained. These bacteria may be exploited for bioremediation of Cr (VI) and construction of microbial sensor in future."
1231427,Alberto et al. 2011,Age effect on the antioxidant activity of Daphnia magna (Anomopoda: Daphniidae): does younger mean more sensitivity?,"It has been accepted that for most species newborns and senescent organisms are more sensitive than other ages to environmental stressors. Nevertheless, it must be considered that there are several biochemical and physiological compensatory processes which are not expressed with the same magnitude during the whole life cycle. With this aim, Daphnia magna individuals of different age were exposed to hexavalent chromium, Cr (VI), at two different sublethal concentrations (0.032 and 0.0064 mg l(-1)), and the activity of some antioxidant enzymes such as catalase (CAT), superoxide dismutase (SOD), glutathione reductase (GR) and glutathione peroxidase (GPx) were evaluated during most of the life cycle of this cladoceran. The antioxidant enzymatic activity showed an inverse relationship with respect to age. The activity of CAT, GR and GPx were increased in the two treated groups, at all life stages tested. On the other hand, the activity of SOD decreased in the same groups. Both, increase and decrease in the antioxidant enzymatic activities, showed significant differences with respect to the control group, being higher for the 0.032 mg l(-1) group. The Cr (VI) LC50 was also estimated for these age groups, finding statistical differences among them. Even though adults exhibited higher responses, these enzymatic activity changes should not be interpreted as higher sensitivity, since the daphnids acute chromium toxicity followed a different pattern, with increasing LC50 values according to age.","Age effect on the antioxidant activity of Daphnia magna (Anomopoda: Daphniidae): does younger mean more sensitivity? Abs: It has been accepted that for most species newborns and senescent organisms are more sensitive than other ages to environmental stressors. Nevertheless, it must be considered that there are several biochemical and physiological compensatory processes which are not expressed with the same magnitude during the whole life cycle. With this aim, Daphnia magna individuals of different age were exposed to hexavalent chromium, Cr (VI), at two different sublethal concentrations (0.032 and 0.0064 mg l(-1)), and the activity of some antioxidant enzymes such as catalase (CAT), superoxide dismutase (SOD), glutathione reductase (GR) and glutathione peroxidase (GPx) were evaluated during most of the life cycle of this cladoceran. The antioxidant enzymatic activity showed an inverse relationship with respect to age. The activity of CAT, GR and GPx were increased in the two treated groups, at all life stages tested. On the other hand, the activity of SOD decreased in the same groups. Both, increase and decrease in the antioxidant enzymatic activities, showed significant differences with respect to the control group, being higher for the 0.032 mg l(-1) group. The Cr (VI) LC50 was also estimated for these age groups, finding statistical differences among them. Even though adults exhibited higher responses, these enzymatic activity changes should not be interpreted as higher sensitivity, since the daphnids acute chromium toxicity followed a different pattern, with increasing LC50 values according to age."
1231425,Behnajady et al. 2012,Influence of operational parameters and kinetics analysis on the photocatalytic reduction of Cr(VI) by immobilized ZnO,"In the present work the performance of immobilized ZnO on a glass plate with the heat attachment method has been described for photoreduction of Cr(VI) to the less harmful Cr(III) at different operational parameters. The photoreduction of Cr(VI) on the surface of the immobilized ZnO catalyst was studied as a function of the pH of solution, initial Cr(VI) concentration and ultraviolet (UV) light intensity. Results indicated that the reduction rate decreases with increasing initial concentration of Cr(VI) and initial pH of solution, whereas it increases with increasing UV light intensity. The photoreduction rate of Cr(VI) on the surface of the immobilized ZnO in the presence of O2 as mobile gas is more than Ar and N2. The reduction process of Cr(VI) by immobilized ZnO also could be done under visible light irradiation. Pseudo first-order kinetics were observed for the photoreduction of Cr(VI) at different operational conditions. With non-linear regression analysis a mathematical kinetics model was developed for the pseudo first-order constant (k(ap)) as a function of operational parameters.","Influence of operational parameters and kinetics analysis on the photocatalytic reduction of Cr(VI) by immobilized ZnO Abs: In the present work the performance of immobilized ZnO on a glass plate with the heat attachment method has been described for photoreduction of Cr(VI) to the less harmful Cr(III) at different operational parameters. The photoreduction of Cr(VI) on the surface of the immobilized ZnO catalyst was studied as a function of the pH of solution, initial Cr(VI) concentration and ultraviolet (UV) light intensity. Results indicated that the reduction rate decreases with increasing initial concentration of Cr(VI) and initial pH of solution, whereas it increases with increasing UV light intensity. The photoreduction rate of Cr(VI) on the surface of the immobilized ZnO in the presence of O2 as mobile gas is more than Ar and N2. The reduction process of Cr(VI) by immobilized ZnO also could be done under visible light irradiation. Pseudo first-order kinetics were observed for the photoreduction of Cr(VI) at different operational conditions. With non-linear regression analysis a mathematical kinetics model was developed for the pseudo first-order constant (k(ap)) as a function of operational parameters."
1231424,University of Aston in Birmingham 1992,Initial submission: Letter from Dupont Chem to USEPA regarding a chromium report with cover letter and attachments,,Initial submission: Letter from Dupont Chem to USEPA regarding a chromium report with cover letter and attachments Abs: 
1231417,Cooper 1983,Mortality in Employees of Three Plants Which Produced Chromate Pigments,"A mortality study was conducted on 574 male workers from three facilities that produced chromate pigments. The cohort included workers who had been exposed to lead-chromate (7758976) for at least 6 months. Two of the facilities also had potential exposure to zinc-chromate (13530659). Additionally, one of these facilities had potential exposure to strontium-chromate (7789062) and barium-chromate (10294403). Causes of death were determined from company records or death certificates. Risk of death from lung cancer and other causes was described as a Standardized Mortality Ratio (SMR). Exposures to lead (7439921) and chromium (7440473) were estimated from company records and results of industrial hygiene surveys. Industrial hygiene surveys conducted at the time of the study showed that for the three facilities combined, the time weighted average concentrations exceeded OSHA limits for lead and chromium in nearly 50 percent of the samples collected. Company records and prior surveys indicated even higher concentrations. No attempt was made to correlate individual exposures with the mortality survey. The 246 males exposed to only lead-chromate were observed for 4768 person years. Twenty one deaths occurred, with 33.1 expected, giving an SMR of 63.5. The slight excess of lung cancer (3 observed and 2.3 expected), was not statistically significant. The 328 males exposed to lead-chromate and zinc-chromate with some exposures to strontium-chromate and barium-chromate were observed for 7457 person years. Sixty four deaths were observed (73.4 expected), giving an SMR of 87. There were 11 lung cancer deaths (4.8 expected), giving a statistically elevated SMR of 228. At one of the mixed exposure facilities, there were 5 stomach cancers (0.75 expected), giving a significantly elevated SMR of 667. The author concludes that exposure to zinc-chromate increases the risk of lung cancer and recommends investigation of the causes of the gastric cancers observed.","Mortality in Employees of Three Plants Which Produced Chromate Pigments Abs: A mortality study was conducted on 574 male workers from three facilities that produced chromate pigments. The cohort included workers who had been exposed to lead-chromate (7758976) for at least 6 months. Two of the facilities also had potential exposure to zinc-chromate (13530659). Additionally, one of these facilities had potential exposure to strontium-chromate (7789062) and barium-chromate (10294403). Causes of death were determined from company records or death certificates. Risk of death from lung cancer and other causes was described as a Standardized Mortality Ratio (SMR). Exposures to lead (7439921) and chromium (7440473) were estimated from company records and results of industrial hygiene surveys. Industrial hygiene surveys conducted at the time of the study showed that for the three facilities combined, the time weighted average concentrations exceeded OSHA limits for lead and chromium in nearly 50 percent of the samples collected. Company records and prior surveys indicated even higher concentrations. No attempt was made to correlate individual exposures with the mortality survey. The 246 males exposed to only lead-chromate were observed for 4768 person years. Twenty one deaths occurred, with 33.1 expected, giving an SMR of 63.5. The slight excess of lung cancer (3 observed and 2.3 expected), was not statistically significant. The 328 males exposed to lead-chromate and zinc-chromate with some exposures to strontium-chromate and barium-chromate were observed for 7457 person years. Sixty four deaths were observed (73.4 expected), giving an SMR of 87. There were 11 lung cancer deaths (4.8 expected), giving a statistically elevated SMR of 228. At one of the mixed exposure facilities, there were 5 stomach cancers (0.75 expected), giving a significantly elevated SMR of 667. The author concludes that exposure to zinc-chromate increases the risk of lung cancer and recommends investigation of the causes of the gastric cancers observed."
1231416,U.S. EPA 1983,Evaluation of the Potential Health Effects of Trivalent Chromium Compounds in the Refractories Indus with Cover Letter dated 071583 & EPA Receipt,"The quality of the documents listed in the Office of Toxic Substances database may not meet usual NTIS standards but are included to further the opportunity for the scientific and technical community to locate materials which may not be available elsewhere. The content is the responsibility of OTS. Sponsored by Environmental Protection Agency, Washington, DC. Office of Toxic Substances. fractories Institute commissioned Battelle Columbus Laboratories in the summer of 1981 to conduct an independent investigation to determine the effects of exposure to chromium compounds on human health and the environment. Battelle's study included a critical review of selected publications relating to chromina toxicity, a comprehensive survey of all 30 refractory plant locations in the United States, site visits to a representa- tive group of manufacturing plants, and an analytical assessment to determine if trivalent chromium compounds used in manufacturing refractories were con- verted to hexavalent materials during the manufacturing process.","Evaluation of the Potential Health Effects of Trivalent Chromium Compounds in the Refractories Indus with Cover Letter dated 071583 & EPA Receipt Abs: The quality of the documents listed in the Office of Toxic Substances database may not meet usual NTIS standards but are included to further the opportunity for the scientific and technical community to locate materials which may not be available elsewhere. The content is the responsibility of OTS. Sponsored by Environmental Protection Agency, Washington, DC. Office of Toxic Substances. fractories Institute commissioned Battelle Columbus Laboratories in the summer of 1981 to conduct an independent investigation to determine the effects of exposure to chromium compounds on human health and the environment. Battelle's study included a critical review of selected publications relating to chromina toxicity, a comprehensive survey of all 30 refractory plant locations in the United States, site visits to a representa- tive group of manufacturing plants, and an analytical assessment to determine if trivalent chromium compounds used in manufacturing refractories were con- verted to hexavalent materials during the manufacturing process."
1231413,Holland 1998,Chrome effects,Topics: carcinogens; chrome ulcer; chromium and compounds; dermatological effects; diseases of nose and sinuses; electroplating; legislation; medical supervision; occupational hygiene evaluation; perforation of the nasal septum; questionnaire survey; respiratory diseases; skin diseases; ulceration of the nasal mucosa; United Kingdom.,Chrome effects Abs: Topics: carcinogens; chrome ulcer; chromium and compounds; dermatological effects; diseases of nose and sinuses; electroplating; legislation; medical supervision; occupational hygiene evaluation; perforation of the nasal septum; questionnaire survey; respiratory diseases; skin diseases; ulceration of the nasal mucosa; United Kingdom.
1231405,Mcdonald 1988,"Unit: Harmful dusts, gases and vapours - Module: Personal sampling for mists","Training module designed for home study. It includes many practical exercises with answers. Contents: definition of mists; physical and biological properties; generation of mists; sampling techniques (in particular, for chromic acid and oil mist).","Unit: Harmful dusts, gases and vapours - Module: Personal sampling for mists Abs: Training module designed for home study. It includes many practical exercises with answers. Contents: definition of mists; physical and biological properties; generation of mists; sampling techniques (in particular, for chromic acid and oil mist)."
1231404,ANON 1986,Chromic acid,"Chemical safety information sheet. Exposure limit: ACGIH TLV = 0.05mg chromium/m|3|. Toxicity: irritation of skin, eyes and respiratory tract; perforation of the nasal septum; chemical burns.","Chromic acid Abs: Chemical safety information sheet. Exposure limit: ACGIH TLV = 0.05mg chromium/m|3|. Toxicity: irritation of skin, eyes and respiratory tract; perforation of the nasal septum; chemical burns."
1231403,ANON 1986,Soluble hexavalent chromium compounds in air,"Guidance note on a colorimetric field method using 1,5-diphenylcarbazide. Scope: suitable for sampling over periods of 1-8h. The lower analytical limit is 0.001mg Cr(VI)/m|3| for samples of 120L of air. Allowing for recovery and sampling errors, this is increased to 0.015mg Cr(VI)/m|3| for samples of 120L of air. The precision of the method is expected to be better than 12%, measured as a coefficient of variation for samples of a minimum of 120L in the range 0.025-0.1mg Cr(VI)/m|3|. Vanadium is the only interferent, but under the test conditions given interference is minimal. Addition information on soluble hexavalent chromium compounds: occurrence, uses, precautions, toxicity, first aid.","Soluble hexavalent chromium compounds in air Abs: Guidance note on a colorimetric field method using 1,5-diphenylcarbazide. Scope: suitable for sampling over periods of 1-8h. The lower analytical limit is 0.001mg Cr(VI)/m|3| for samples of 120L of air. Allowing for recovery and sampling errors, this is increased to 0.015mg Cr(VI)/m|3| for samples of 120L of air. The precision of the method is expected to be better than 12%, measured as a coefficient of variation for samples of a minimum of 120L in the range 0.025-0.1mg Cr(VI)/m|3|. Vanadium is the only interferent, but under the test conditions given interference is minimal. Addition information on soluble hexavalent chromium compounds: occurrence, uses, precautions, toxicity, first aid."
1231402,ANON 1986,Chromium compounds,"Chemical safety information sheet. Exposure limits (Ontario proposed regulations): TWA exposure = 0.50mg/m|3| for Class 1 chromium (metal and alloys, bivalent and trivalent compounds); TWA exposure = 0.02mg/m|3| for Class 2 chromium (hexavalent compounds, namely zinc, calcium, lead, barium and strontium chromate, and sintered chromium trioxide); TWA exposure = 0.02mg/m|3| for Class 3 chromium (all other hexavalent chromium compounds not included in Class 2); maximum concentration of exposure (15min) = 0.05mg/m|3| for Class 3 chromium. Toxicity of Class 1 compounds: carcinogenic and skin sensitising potential is lower than that of chromium VI compounds. Toxicity of Class 2 chromium: recognised carcinogens; powerful skin sensitisers. Toxicity of Class 3 compounds: ulceration of the nasal septum; chemical pneumonitis.","Chromium compounds Abs: Chemical safety information sheet. Exposure limits (Ontario proposed regulations): TWA exposure = 0.50mg/m|3| for Class 1 chromium (metal and alloys, bivalent and trivalent compounds); TWA exposure = 0.02mg/m|3| for Class 2 chromium (hexavalent compounds, namely zinc, calcium, lead, barium and strontium chromate, and sintered chromium trioxide); TWA exposure = 0.02mg/m|3| for Class 3 chromium (all other hexavalent chromium compounds not included in Class 2); maximum concentration of exposure (15min) = 0.05mg/m|3| for Class 3 chromium. Toxicity of Class 1 compounds: carcinogenic and skin sensitising potential is lower than that of chromium VI compounds. Toxicity of Class 2 chromium: recognised carcinogens; powerful skin sensitisers. Toxicity of Class 3 compounds: ulceration of the nasal septum; chemical pneumonitis."
1231384,Sarto et al. 1983,Chromosomal damage in workers exposed to chromic acid (CrO3),,Chromosomal damage in workers exposed to chromic acid (CrO3) Abs: 
1231381,Petrilli and  De Flora 1981,MUTAGENICITY OF CHROMIUM COMPOUNDS,,MUTAGENICITY OF CHROMIUM COMPOUNDS Abs: 
1231380,De Flora et al. 1981,Mutagenicity and toxicity of chromyl chloride,"Chromyl chloride (CC) (Cl2CrO2) is a liquid volatile Cr6+ compound prepared from CrO3, HCl and H2SO4. Due to its corrosive, explosive and toxic properties, CC is very difficult and dangerous to handle. At sub-lethal concentrations, the liquid phase of CC was mutagenic for S. typhimurium (TA100), both in the spot test and in the plate test. Toxic effects were generally prevailing on mutagenic effects in CC vapours, as tested by a variety of methods. In all cases S9 mix (Aroclor) decreased both toxic and mutagenic effects. On the whole, we have so far tested 18 Cr compounds in our lab. With the exception of Cr carbonyl and Cr yellow (both water-insoluble), all Cr6+ compounds (Na dichromate, chromic acid, Ca chromate, K chromate, NH4 chromate, Cr orange, Mo orange, Zn yellow and CC) were mutagenic in the Ames test. However, their mutagenicity was decreased by S9 mix and other metabolic systems. Conversely, with the exception of chromite (contaminated with Cr6+) all Cr3+ compounds (Cr-K sulfate, Cr nitrate, Cr chloride, Cr acetate, neochromium and Cr alum) were negative. Therefore, the mutagenic activity of Cr appears to depend on availability of Cr6+ ion to bacterial cells.","Mutagenicity and toxicity of chromyl chloride Abs: Chromyl chloride (CC) (Cl2CrO2) is a liquid volatile Cr6+ compound prepared from CrO3, HCl and H2SO4. Due to its corrosive, explosive and toxic properties, CC is very difficult and dangerous to handle. At sub-lethal concentrations, the liquid phase of CC was mutagenic for S. typhimurium (TA100), both in the spot test and in the plate test. Toxic effects were generally prevailing on mutagenic effects in CC vapours, as tested by a variety of methods. In all cases S9 mix (Aroclor) decreased both toxic and mutagenic effects. On the whole, we have so far tested 18 Cr compounds in our lab. With the exception of Cr carbonyl and Cr yellow (both water-insoluble), all Cr6+ compounds (Na dichromate, chromic acid, Ca chromate, K chromate, NH4 chromate, Cr orange, Mo orange, Zn yellow and CC) were mutagenic in the Ames test. However, their mutagenicity was decreased by S9 mix and other metabolic systems. Conversely, with the exception of chromite (contaminated with Cr6+) all Cr3+ compounds (Cr-K sulfate, Cr nitrate, Cr chloride, Cr acetate, neochromium and Cr alum) were negative. Therefore, the mutagenic activity of Cr appears to depend on availability of Cr6+ ion to bacterial cells."
1231379,Gentile et al. 1981,Chromium genotoxicity as influenced by complexation and rate effects,"Conclusions as to the mutagenicity and carcinogenicity of metal salts can be ambiguous and misleading, especially for metal ions having a high charge/radius ratio, hence a strong tendency to hydrolyze. Using the rec-assay, we determined whether the mutagenicity of chromium salts was reduced by complexation, as in the case of Cr(VI), or induced in the case of Cr(III). We find that several chelants, in proportion to concentration, reduce or eliminate the mutagenicity of Cr2O32?. These include EDTA, salicylate (SA), and Tiron (disodium 1,2-dihydroxybenzene-3,5-disulfonate). Cr(III) was rendered slightly mutagenic by salicylate and citrate. None of the chelating agents or their combinations were mutagenic.","Chromium genotoxicity as influenced by complexation and rate effects Abs: Conclusions as to the mutagenicity and carcinogenicity of metal salts can be ambiguous and misleading, especially for metal ions having a high charge/radius ratio, hence a strong tendency to hydrolyze. Using the rec-assay, we determined whether the mutagenicity of chromium salts was reduced by complexation, as in the case of Cr(VI), or induced in the case of Cr(III). We find that several chelants, in proportion to concentration, reduce or eliminate the mutagenicity of Cr2O32?. These include EDTA, salicylate (SA), and Tiron (disodium 1,2-dihydroxybenzene-3,5-disulfonate). Cr(III) was rendered slightly mutagenic by salicylate and citrate. None of the chelating agents or their combinations were mutagenic."
1231372,group 1984,Health assessment document for chromium. Final report,"The full document represents a comprehensive data base that considers all sources of chromium in the environment, the likelihood for its exposure to humans, and the possible consequences to man and lower organisms from its absorption. This information is integrated into a format that can serve as the basis for qualitative and quantitative risk assessments, while at the same time identifying gaps in our knowledge that limit accurate health assessment. Thus, it is expected that this document may serve the information needs of other government agencies and the private sector that may be involved in decision making and regulatory activities. Chromium is a metallic element which, when found in nature, is a stable mixture of four separate isotops. Inorganic chromium compounds occur in valence states ranging from -2 to +6; however, in the environment the Cr(III) and Cr(VI) states are the most stable. Chemically, the Cr(III) state is the most stable and important form of inorganic chromium complexes. Cr(IV) compounds comprise the most commercially important form of chromium, and they also appear to be the most significant chromium compounds from an environmental standpoint. Because Cr(VI) is readily reduced in the precence of organic material, it is rarely found in nature apart from deposition by anthropogenic sources. Although chromite ore is not currently mined in the United States, several chromium chemicals are domestically produced from imported ores. Sodium chromate, sodium dichromate, and chromic acid are three of the more important commercial chromium compounds produced in the United States. Metallurgical uses constitute about 60% of the largest market demand for chromium. Chemical uses are the second largest consumption sector at 21%, followed by refractory uses at 18%. Chromium emissions are released into the air, water, and land environments from a variety of industrial source categories including fossil fuel combustion, cement production, incineration, cooling towers, refractory production, leather tanneries, steel and alloy production, electroplating, and chromite ore refining. The largest chromium emission sources to the air are coal and oil combustion production, refractory plants, and steel and alloy plants. Principal sources of chromium in water systems include electroplating operations, leather tanneries, and textile manufacturing operations. Significant sources of chromium-containing solid wastes that are land disposed include chromite ore refining operations and chromium chemical production plants. Recent monitoring of the air in many urban and rural areas of the country has shown annual average chromium concentrations to be in the range of 0.0052 to 0.1568 ug/m3; in remote parts of the world, concentrations as low as 0.005 ng/m3 have been reported. The maximum concentration determined during any one 24-hour measurement was about 0.6839 ug/m3. The chromium concentration in the U.S. waters varies with the type of surrounding industrial sources and the type of underlying soils. An analysis of 3834 tap waters in representative U.S. cities showed a chromium concentration range from 0.4 to 8 ppb. Chromium levels in soils vary with soil origin and the degree of contamination from anthropogenic chromium sources. Tests on domestic soils have shown chromium concentrations ranging from 1 to 1000 ppm, with the average concentration ranging from 14 to about 70 ppm.","Health assessment document for chromium. Final report Abs: The full document represents a comprehensive data base that considers all sources of chromium in the environment, the likelihood for its exposure to humans, and the possible consequences to man and lower organisms from its absorption. This information is integrated into a format that can serve as the basis for qualitative and quantitative risk assessments, while at the same time identifying gaps in our knowledge that limit accurate health assessment. Thus, it is expected that this document may serve the information needs of other government agencies and the private sector that may be involved in decision making and regulatory activities. Chromium is a metallic element which, when found in nature, is a stable mixture of four separate isotops. Inorganic chromium compounds occur in valence states ranging from -2 to +6; however, in the environment the Cr(III) and Cr(VI) states are the most stable. Chemically, the Cr(III) state is the most stable and important form of inorganic chromium complexes. Cr(IV) compounds comprise the most commercially important form of chromium, and they also appear to be the most significant chromium compounds from an environmental standpoint. Because Cr(VI) is readily reduced in the precence of organic material, it is rarely found in nature apart from deposition by anthropogenic sources. Although chromite ore is not currently mined in the United States, several chromium chemicals are domestically produced from imported ores. Sodium chromate, sodium dichromate, and chromic acid are three of the more important commercial chromium compounds produced in the United States. Metallurgical uses constitute about 60% of the largest market demand for chromium. Chemical uses are the second largest consumption sector at 21%, followed by refractory uses at 18%. Chromium emissions are released into the air, water, and land environments from a variety of industrial source categories including fossil fuel combustion, cement production, incineration, cooling towers, refractory production, leather tanneries, steel and alloy production, electroplating, and chromite ore refining. The largest chromium emission sources to the air are coal and oil combustion production, refractory plants, and steel and alloy plants. Principal sources of chromium in water systems include electroplating operations, leather tanneries, and textile manufacturing operations. Significant sources of chromium-containing solid wastes that are land disposed include chromite ore refining operations and chromium chemical production plants. Recent monitoring of the air in many urban and rural areas of the country has shown annual average chromium concentrations to be in the range of 0.0052 to 0.1568 ug/m3; in remote parts of the world, concentrations as low as 0.005 ng/m3 have been reported. The maximum concentration determined during any one 24-hour measurement was about 0.6839 ug/m3. The chromium concentration in the U.S. waters varies with the type of surrounding industrial sources and the type of underlying soils. An analysis of 3834 tap waters in representative U.S. cities showed a chromium concentration range from 0.4 to 8 ppb. Chromium levels in soils vary with soil origin and the degree of contamination from anthropogenic chromium sources. Tests on domestic soils have shown chromium concentrations ranging from 1 to 1000 ppm, with the average concentration ranging from 14 to about 70 ppm."
1231371,Anonymous 1990,Chromium and chromium compounds,"There is sufficient evidence in humans for the carcinogenicity of chromium (VI) compounds as encountered in the chromate production, chromate pigment production and chromium plating industries. There is inadequate evidence in humans for the carcinogenicity of metallic chromium and of chromium (III) compounds. There is sufficient evidence in experimental animals for the carcinogenicity of calcium chromate, zinc chromates, strontium chromate and lead chromates. There is limited evidence in experimental animals for the carcinogenicity of chromium trioxide (chromic acid) and sodium dichromat. There is inadequate evidence in experimental animals for the carcinogenicity of metallic chromium, barium chromate and chromium (III) compounds. The Working Group made the overall evaluation on chromium (VI) compounds on the basis of the combined results of epidemiological studies, carcinogenicity studies in experimental animals, and several types of other relevant data which support the underlying concept that chromium (VI) ions generated at critical sites in the target cells are responsible for the carcinogenic action observed. Chromium (VI) is carcinogenic to humans (Group 1). Metallic chromium and chromium (III) compounds are not classifiable as to their carcinogenicity to humans (Group 3).","Chromium and chromium compounds Abs: There is sufficient evidence in humans for the carcinogenicity of chromium (VI) compounds as encountered in the chromate production, chromate pigment production and chromium plating industries. There is inadequate evidence in humans for the carcinogenicity of metallic chromium and of chromium (III) compounds. There is sufficient evidence in experimental animals for the carcinogenicity of calcium chromate, zinc chromates, strontium chromate and lead chromates. There is limited evidence in experimental animals for the carcinogenicity of chromium trioxide (chromic acid) and sodium dichromat. There is inadequate evidence in experimental animals for the carcinogenicity of metallic chromium, barium chromate and chromium (III) compounds. The Working Group made the overall evaluation on chromium (VI) compounds on the basis of the combined results of epidemiological studies, carcinogenicity studies in experimental animals, and several types of other relevant data which support the underlying concept that chromium (VI) ions generated at critical sites in the target cells are responsible for the carcinogenic action observed. Chromium (VI) is carcinogenic to humans (Group 1). Metallic chromium and chromium (III) compounds are not classifiable as to their carcinogenicity to humans (Group 3)."
1231370,standards 2000,Scientific basis for Swedish occupational standards XXI. Consensus report for Chromium and Chromium compounds,"Dose-response/dose-effect relationships. There are clear problems with deriving a reliable dose-response relationship for hexavalent chromium, since exposure data is sparse even in recent studies. In addition, there is often simultaneous exposure to nickel, asbestos and/or tobacco smoke, making it difficult to distinguish the specific effect of chromium. As shown by the summary in Table 3, bronchial irritation has been reported at chromic acid levels of 1-2 ug/m3 in air, and transient reductions in lung function parameters and chrome sores in the nose have been reported at levels of 2-20 ug/m3. Perforated nasal septa are reported at exposures of 11 ug/m3 hexavalent chromium, and their frequency rises with increasing exposure. At a total chromium level of 4-6 ug/m3 there are effects on the kidneys, with increased excretion of NAG and beta2-microglobulin. Renal effects have been observed among welders with urine chromium levels of 30 ug/g creatinine, and 15 ug/g creatinine has therefore been proposed as the threshold value for renal toxicity. Identical exposures seem to give rise to different chromium levels in biological samples from different individuals and also to differences in the severity of the toxic effects. Elevated frequencies of chromatid breaks have been observed in blood samples from stainless steel welders exposed to 35 ug/m3 hexavalent chromium (0.6-252 ug/m3), elevated frequencies of DNA-protein cross-linking at 70-80 ug/m3, and elevated frequencies of DNA strand breaks at 100 ug/m3. The lung cancer incidence among workers exposed to chromium is lower today than it was thirty years ago, probably because process methods and working conditions have been improved and exposure has been reduced. The Dutch Expert Committee for Occupational Standards has recently concluded that 40 years of exposure to 8 ug respirable hexavalent chromium dust/m3, with linear extrapolation, yields an additional lung cancer mortality risk of 1.4 cases per 100 exposed workers (22). Conclusions. The critical effect of occupational exposure to hexavalent chromium is its irritation of mucous membranes in the upper and lower respiratory passages. Mutagenic effects have also been observed in blood samples from chromium-exposed welders. Hexavalent chromium is corrosive to skin and mucous membranes, and skin contact can also induce contact allergy. Asthma has also been described. Hexavalent chromium is carcinogenic. Occupational exposure has been found to induce cancer in lungs and nose. Hexavalent chromium has caused reproductive disturbances in experimental animals. Trivalent chromium can cause skin irritation and allergic contact eczema. There are no data from which to determine a critical effect of exposure to trivalent chromium, metallic chromium or other chromium compounds.","Scientific basis for Swedish occupational standards XXI. Consensus report for Chromium and Chromium compounds Abs: Dose-response/dose-effect relationships. There are clear problems with deriving a reliable dose-response relationship for hexavalent chromium, since exposure data is sparse even in recent studies. In addition, there is often simultaneous exposure to nickel, asbestos and/or tobacco smoke, making it difficult to distinguish the specific effect of chromium. As shown by the summary in Table 3, bronchial irritation has been reported at chromic acid levels of 1-2 ug/m3 in air, and transient reductions in lung function parameters and chrome sores in the nose have been reported at levels of 2-20 ug/m3. Perforated nasal septa are reported at exposures of 11 ug/m3 hexavalent chromium, and their frequency rises with increasing exposure. At a total chromium level of 4-6 ug/m3 there are effects on the kidneys, with increased excretion of NAG and beta2-microglobulin. Renal effects have been observed among welders with urine chromium levels of 30 ug/g creatinine, and 15 ug/g creatinine has therefore been proposed as the threshold value for renal toxicity. Identical exposures seem to give rise to different chromium levels in biological samples from different individuals and also to differences in the severity of the toxic effects. Elevated frequencies of chromatid breaks have been observed in blood samples from stainless steel welders exposed to 35 ug/m3 hexavalent chromium (0.6-252 ug/m3), elevated frequencies of DNA-protein cross-linking at 70-80 ug/m3, and elevated frequencies of DNA strand breaks at 100 ug/m3. The lung cancer incidence among workers exposed to chromium is lower today than it was thirty years ago, probably because process methods and working conditions have been improved and exposure has been reduced. The Dutch Expert Committee for Occupational Standards has recently concluded that 40 years of exposure to 8 ug respirable hexavalent chromium dust/m3, with linear extrapolation, yields an additional lung cancer mortality risk of 1.4 cases per 100 exposed workers (22). Conclusions. The critical effect of occupational exposure to hexavalent chromium is its irritation of mucous membranes in the upper and lower respiratory passages. Mutagenic effects have also been observed in blood samples from chromium-exposed welders. Hexavalent chromium is corrosive to skin and mucous membranes, and skin contact can also induce contact allergy. Asthma has also been described. Hexavalent chromium is carcinogenic. Occupational exposure has been found to induce cancer in lungs and nose. Hexavalent chromium has caused reproductive disturbances in experimental animals. Trivalent chromium can cause skin irritation and allergic contact eczema. There are no data from which to determine a critical effect of exposure to trivalent chromium, metallic chromium or other chromium compounds."
1231369,Rimington et al. 1937,Studies upon the photosensitisation of animals in South Africa. X. The icterogenic factor in geeldikkop. Isolation of active principles from Lippia rehmanni Pears,"1. An improved method is described for the isolation of the icterogenic material from Lippia rehmanni Pears. (Verbenaceae). This takes advantage of the sparing solubility of the sodium salt of the active material in solutions containing sodium ions. 2. In addition to the two acids previously described, namely prisms M.P. 239 degrees and irregular plates melting with loss of weight at 158 degrees, resolidifying to melt ultimately at about 230 degrees, a third active acid has been found to be present in the mixture of crude sodium salts. This material crystallises in elongated regular plates, M.P. 161 degrees without resolidification or loss in weight. It is proposed to designate these materials Icterogenin A, C, and B respectively. 3. Comparison of the analytical data afforded by the free acids and their acetyl derivatives with microtitration experiments and the nitrogen content of the 2:4 dinitrophenylhydrazones, leads to the formula C34H52O6 as most probably representing the true composition of all three isomers. The possibliity of further substances being present in the mixture is not excluded. 4. In alcoholic solution, the Icterogenins A, B and C have optical rotatory powers of +72.0 degrees, +69.0 degrees and +70.5 degrees respectively. 5. Acetyl derivatives of Icterogenins A and B were prepared and found to be identical. The substance crystallised in needles M.P. 142 degrees. Saponification showed that one hydroxyl group had been acetylated. 6. The presence of one ketonic group in the molecule was shown by the preparation of the 2:4 dinitrophenylhydrazones crystallising in orange-yellow needles with M.P.'s 222-5 degrees, 226-9 degrees and 224-8 degrees respectively. 7. Chromic acid oxidation indicated the presence of an iso-propyl side chain. The formula of Icterogenin can thus be written C29H43O2. 8. Icterogenin, in a dose of 1.5 gm. or more per os to a sheep, causes bilirubinaemia within 24 hours, together with atony and stasis in the fore stomachs and large intestine. 9. By the intravenous route it was very toxic, quantities of 1 gm. causing death with shock-like symptoms. Lesser amounts cause bilirubinaemia and hurried respiration. 10. Upon the general systolic blood pressure, Icterogenin has no effect in doses of 0.1 gm. to a dog, but the pulse is slightly retarded and the pulse interval appreciably increased. 11. On the isolated heart, Icterogenin has a pronounced inhibitory effect in quantities of 1 mgm. added to the perfusion fluid. A systolic spasm gradually develops which, with larger doses, proves fatal. 12. The icterogenins inhibit the isolated intestinal strip in a concentration of 1 in 200,000, the muscle becoming relaxed. 13. Icterogenin is haemolytic in vitro in a concentration of 1 in 35,000. 14. Examination of the root bark of Lippia rehmanni shows that the highest concentration of Icterogenin is present in this tissue. 15. A quantitative experiment extending over a year shows that a translocation of Icterogenin takes place from the leaves to the root bark in Lippia plants. The effect of growth, season, etc. upon this mechanism has been studied and the bearing of the results upon the incidence of geeldikkop is discussed.","Studies upon the photosensitisation of animals in South Africa. X. The icterogenic factor in geeldikkop. Isolation of active principles from Lippia rehmanni Pears Abs: 1. An improved method is described for the isolation of the icterogenic material from Lippia rehmanni Pears. (Verbenaceae). This takes advantage of the sparing solubility of the sodium salt of the active material in solutions containing sodium ions. 2. In addition to the two acids previously described, namely prisms M.P. 239 degrees and irregular plates melting with loss of weight at 158 degrees, resolidifying to melt ultimately at about 230 degrees, a third active acid has been found to be present in the mixture of crude sodium salts. This material crystallises in elongated regular plates, M.P. 161 degrees without resolidification or loss in weight. It is proposed to designate these materials Icterogenin A, C, and B respectively. 3. Comparison of the analytical data afforded by the free acids and their acetyl derivatives with microtitration experiments and the nitrogen content of the 2:4 dinitrophenylhydrazones, leads to the formula C34H52O6 as most probably representing the true composition of all three isomers. The possibliity of further substances being present in the mixture is not excluded. 4. In alcoholic solution, the Icterogenins A, B and C have optical rotatory powers of +72.0 degrees, +69.0 degrees and +70.5 degrees respectively. 5. Acetyl derivatives of Icterogenins A and B were prepared and found to be identical. The substance crystallised in needles M.P. 142 degrees. Saponification showed that one hydroxyl group had been acetylated. 6. The presence of one ketonic group in the molecule was shown by the preparation of the 2:4 dinitrophenylhydrazones crystallising in orange-yellow needles with M.P.'s 222-5 degrees, 226-9 degrees and 224-8 degrees respectively. 7. Chromic acid oxidation indicated the presence of an iso-propyl side chain. The formula of Icterogenin can thus be written C29H43O2. 8. Icterogenin, in a dose of 1.5 gm. or more per os to a sheep, causes bilirubinaemia within 24 hours, together with atony and stasis in the fore stomachs and large intestine. 9. By the intravenous route it was very toxic, quantities of 1 gm. causing death with shock-like symptoms. Lesser amounts cause bilirubinaemia and hurried respiration. 10. Upon the general systolic blood pressure, Icterogenin has no effect in doses of 0.1 gm. to a dog, but the pulse is slightly retarded and the pulse interval appreciably increased. 11. On the isolated heart, Icterogenin has a pronounced inhibitory effect in quantities of 1 mgm. added to the perfusion fluid. A systolic spasm gradually develops which, with larger doses, proves fatal. 12. The icterogenins inhibit the isolated intestinal strip in a concentration of 1 in 200,000, the muscle becoming relaxed. 13. Icterogenin is haemolytic in vitro in a concentration of 1 in 35,000. 14. Examination of the root bark of Lippia rehmanni shows that the highest concentration of Icterogenin is present in this tissue. 15. A quantitative experiment extending over a year shows that a translocation of Icterogenin takes place from the leaves to the root bark in Lippia plants. The effect of growth, season, etc. upon this mechanism has been studied and the bearing of the results upon the incidence of geeldikkop is discussed."
1231365,Sundstrom et al. 1976,Environmental chemistry of substitutes for poly chlorinated biphenyls. I. Composition and properties of an alkyl chloro biphenyl product,"PESTAB. The composition of a technical alkylchloro- biphenyl mixture, proposed as a substitute for poly chlorinated biphenyls, has been investigated by spectral and chromatographic methods. Gas-liquid chromatography mass spectrometry revealed the presence of a large number of biphenyls substituted with 2 to 3 chlorine atoms and 0 to 4 isopropyl groups. The mixture was dechlorinated as a first step toward structure elucidation of the individual components. The behavior of the alkylchloro biphenyls during analytical cleanup steps such as thin layer chromatography and chromic acid oxidation was also investigated. (Author abstract by permission)","Environmental chemistry of substitutes for poly chlorinated biphenyls. I. Composition and properties of an alkyl chloro biphenyl product Abs: PESTAB. The composition of a technical alkylchloro- biphenyl mixture, proposed as a substitute for poly chlorinated biphenyls, has been investigated by spectral and chromatographic methods. Gas-liquid chromatography mass spectrometry revealed the presence of a large number of biphenyls substituted with 2 to 3 chlorine atoms and 0 to 4 isopropyl groups. The mixture was dechlorinated as a first step toward structure elucidation of the individual components. The behavior of the alkylchloro biphenyls during analytical cleanup steps such as thin layer chromatography and chromic acid oxidation was also investigated. (Author abstract by permission)"
1231361,Williams 1997,Occupational Skin Ulceration in Chrome Platers,"The incidence of skin ulceration was examined in 55 chrome platers from 17 companies. Previous skin ulceration was detected on the hands of 11 platers, of whom six had a single ulcer scar, two had two ulcer scars, one had three ulcer scars, and two had more than three ulcer scars. Active chrome ulcers were observed in two workers. The ulcers were most frequently found around the proximal interphalangeal joint and on the lateral areas of the terminal and middle pharynx of the middle and index fingers. The lesion developed into a central crater within days, which in turn developed into a scar within a period of weeks. Most ulcers healed spontaneously. Chrome platers reportedly developed ulcers often without seeking medical treatment. The author concludes that chrome platers need to avoid cuts and grazes. In addition, adequate personal protection should be provided to prevent skin contact with chromic-acid (7738945). Through employer and employee education and health surveillance, occupational physicians can play an important role in the prevention and management of occupational skin ulceration in chrome platers.","Occupational Skin Ulceration in Chrome Platers Abs: The incidence of skin ulceration was examined in 55 chrome platers from 17 companies. Previous skin ulceration was detected on the hands of 11 platers, of whom six had a single ulcer scar, two had two ulcer scars, one had three ulcer scars, and two had more than three ulcer scars. Active chrome ulcers were observed in two workers. The ulcers were most frequently found around the proximal interphalangeal joint and on the lateral areas of the terminal and middle pharynx of the middle and index fingers. The lesion developed into a central crater within days, which in turn developed into a scar within a period of weeks. Most ulcers healed spontaneously. Chrome platers reportedly developed ulcers often without seeking medical treatment. The author concludes that chrome platers need to avoid cuts and grazes. In addition, adequate personal protection should be provided to prevent skin contact with chromic-acid (7738945). Through employer and employee education and health surveillance, occupational physicians can play an important role in the prevention and management of occupational skin ulceration in chrome platers."
1231358,Foss et al. 1993,Studies of Toxic Aerosols via Elastic and Inelastic Light Scattering,"The chemical characteristics and evaporation rates of several potentially toxic aerosols were examined via elastic and inelastic light scattering measurements. Information was provided on diffusion controlled evaporation, apparatus, elastic light scattering, and Raman spectra. The aerosol systems that were selected for study included a commercial catalyst consisting of a mixture of stannous-octanoate (1912830) and 2-ethylhexanoic-acid (149575) as well as microdroplets emitted from open tanks of chromic-acid (13530682) solutions used for anodizing aluminum. Nanogram amounts of the materials were examined by suspending single microdroplets in an electrodynamic balance in a flow of air. The elastic scattering measurements provided data on phase functions and morphological resonance, while the inelastic light scattering measurements provided information on the molecular vibrational bond. Findings were consistent with previously reported data and infrared spectra. The authors conclude that microparticle Raman spectroscopy and elastic light scattering techniques can be used to obtain information on the chemical properties and evaporation rates of very small samples of toxic materials.","Studies of Toxic Aerosols via Elastic and Inelastic Light Scattering Abs: The chemical characteristics and evaporation rates of several potentially toxic aerosols were examined via elastic and inelastic light scattering measurements. Information was provided on diffusion controlled evaporation, apparatus, elastic light scattering, and Raman spectra. The aerosol systems that were selected for study included a commercial catalyst consisting of a mixture of stannous-octanoate (1912830) and 2-ethylhexanoic-acid (149575) as well as microdroplets emitted from open tanks of chromic-acid (13530682) solutions used for anodizing aluminum. Nanogram amounts of the materials were examined by suspending single microdroplets in an electrodynamic balance in a flow of air. The elastic scattering measurements provided data on phase functions and morphological resonance, while the inelastic light scattering measurements provided information on the molecular vibrational bond. Findings were consistent with previously reported data and infrared spectra. The authors conclude that microparticle Raman spectroscopy and elastic light scattering techniques can be used to obtain information on the chemical properties and evaporation rates of very small samples of toxic materials."
1231357,Pizzino 1993,Possible Chromate-Associated Urticaria,"A case of urticaria was described in a 26 year old black male employed by a company that did chrome electroplating of pipes. His job involved lifting pipes out of open baths of chromic-acid (13530682) and sulfuric-acid (7664939). Splashes were washed off with a water hose and no problems were reported during the patient's March 1984 through December 1985 employment. The dermatitis developed 1 month after his return to work in June of 1989. Topical steroid treatment was initiated, but before it was completed the man developed red welts (some measuring 5 inches across) over his entire body. This urticaria persisted for more than a year despite several courses of clemastine-fumarate and prednisone. He had lichenification and hyperpigmentation on the neck, upper arms, and forearms when examined by a dermatologist in September 1990. He was patch tested with the North American standard allergen series and reacted only to the chromate patch. Extensive testing for possible infectious, collagenous vascular, neoplastic, and other systemic diseases known to cause contact urticaria produced negative responses. The patient's symptoms resolved several months after he was removed from exposure. A review of the published literature found no mention of urticaria as a chromate induced skin disease. The author concludes that the etiology of the patient's urticaria is unknown. The possibility that it was caused by chromate exposure should be considered based on the temporal relationship to chromate exposure and the positive response to the chromate patch.","Possible Chromate-Associated Urticaria Abs: A case of urticaria was described in a 26 year old black male employed by a company that did chrome electroplating of pipes. His job involved lifting pipes out of open baths of chromic-acid (13530682) and sulfuric-acid (7664939). Splashes were washed off with a water hose and no problems were reported during the patient's March 1984 through December 1985 employment. The dermatitis developed 1 month after his return to work in June of 1989. Topical steroid treatment was initiated, but before it was completed the man developed red welts (some measuring 5 inches across) over his entire body. This urticaria persisted for more than a year despite several courses of clemastine-fumarate and prednisone. He had lichenification and hyperpigmentation on the neck, upper arms, and forearms when examined by a dermatologist in September 1990. He was patch tested with the North American standard allergen series and reacted only to the chromate patch. Extensive testing for possible infectious, collagenous vascular, neoplastic, and other systemic diseases known to cause contact urticaria produced negative responses. The patient's symptoms resolved several months after he was removed from exposure. A review of the published literature found no mention of urticaria as a chromate induced skin disease. The author concludes that the etiology of the patient's urticaria is unknown. The possibility that it was caused by chromate exposure should be considered based on the temporal relationship to chromate exposure and the positive response to the chromate patch."
1231355,Geehr and  Salluzzo 1992,Dermal Injuries and Burns from Hazardous Materials,"Injuries which happen to the skin as a result of burns from hazardous materials were discussed along with treatment options. Specific topics covered included basic principles and concepts of dermal injuries, alkali dermal injuries, components of the skin, predisposing factors to the development of cutaneous irritation, chromic-acid (1333820) burns, elemental metals, white phosphorus (7723140), organic acids, phenols, cresols, chreysilic acids, inorganic acids, hydrofluoric-acid (617129), aldehydes, epoxy resins, hot tar, organic solvents, aliphatic alcohols and glycols, sodium-hypochlorite, and physical agents causing dermal injury such as high pressure injection injuries, and microwave injuries. Important factors in planning a management strategy for chemical burns included not underestimating the extent of the initial injury, and the importance of evaluation and treatment by experienced personnel to reduce morbidity and mortality.","Dermal Injuries and Burns from Hazardous Materials Abs: Injuries which happen to the skin as a result of burns from hazardous materials were discussed along with treatment options. Specific topics covered included basic principles and concepts of dermal injuries, alkali dermal injuries, components of the skin, predisposing factors to the development of cutaneous irritation, chromic-acid (1333820) burns, elemental metals, white phosphorus (7723140), organic acids, phenols, cresols, chreysilic acids, inorganic acids, hydrofluoric-acid (617129), aldehydes, epoxy resins, hot tar, organic solvents, aliphatic alcohols and glycols, sodium-hypochlorite, and physical agents causing dermal injury such as high pressure injection injuries, and microwave injuries. Important factors in planning a management strategy for chemical burns included not underestimating the extent of the initial injury, and the importance of evaluation and treatment by experienced personnel to reduce morbidity and mortality."
1231352,Gupta 1990,Occupational Diseases of Teeth,"A review was presented of occupational dental diseases, including some studies of adverse environmental effects on rat teeth. Dental abrasion was a hazard among workers exposed to abrasive dusts. Organic dusts could cause staining of teeth, gingival pigmentation, generalized abrasion, calculus, gingivostomatitis or hemorrhage. Dental caries were widely reported among workers exposed to sugar dust. Staining of teeth could be caused by exposure to dusts of copper (7440508), nickel (7440020), iron (7439896), manganese (7439965), cadmium (7440439) and tin (7440315). Gum discoloration was reported with exposure to dusts of bismuth (7440699), chromium (7440473) salts, lead (7439921) and silver (7440224). Gingival and other oral diseases occurred with exposure to chromium salts, chromic-acid (7738945) or mercury (7439976). Fluorosis of developing teeth was seen with exposure to fluorine (7782414) compounds. There was a report of fluorosis in offspring of female workers exposed to cryolite (15096523) dust. Phosphorus (7723140) poisoning produced osteoporotic and carious alterations. Severe gingivitis was reported with arsenic (7440382) exposure, and arsenic-trioxide (1327533) could cause gingival ulceration. Tooth erosion could result from exposure to citric-acid (77929), tartaric-acid (133379), hydrochloric-acid (7647010), nitric-acid (7697372) and sulfuric-acid (7664939). Dental problems could result from abrasion or occupational injuries. Dental problems were reported among certain musicians, particularly wind instrumentalists. Radiation exposure could cause tooth, jaw and gum problems. Bleeding from gums was reported with high or low atmospheric pressures. Incisors of rats exposed to low pressures for 18 to 24 weeks showed mesenchymal changes that were augmented by concomitant exposure to cold. Superimposed heat counteracted these changes but produced ectodermal changes. Oral hygiene, proper working conditions and inclusion of dental and oral examinations in occupational health services were considered important.","Occupational Diseases of Teeth Abs: A review was presented of occupational dental diseases, including some studies of adverse environmental effects on rat teeth. Dental abrasion was a hazard among workers exposed to abrasive dusts. Organic dusts could cause staining of teeth, gingival pigmentation, generalized abrasion, calculus, gingivostomatitis or hemorrhage. Dental caries were widely reported among workers exposed to sugar dust. Staining of teeth could be caused by exposure to dusts of copper (7440508), nickel (7440020), iron (7439896), manganese (7439965), cadmium (7440439) and tin (7440315). Gum discoloration was reported with exposure to dusts of bismuth (7440699), chromium (7440473) salts, lead (7439921) and silver (7440224). Gingival and other oral diseases occurred with exposure to chromium salts, chromic-acid (7738945) or mercury (7439976). Fluorosis of developing teeth was seen with exposure to fluorine (7782414) compounds. There was a report of fluorosis in offspring of female workers exposed to cryolite (15096523) dust. Phosphorus (7723140) poisoning produced osteoporotic and carious alterations. Severe gingivitis was reported with arsenic (7440382) exposure, and arsenic-trioxide (1327533) could cause gingival ulceration. Tooth erosion could result from exposure to citric-acid (77929), tartaric-acid (133379), hydrochloric-acid (7647010), nitric-acid (7697372) and sulfuric-acid (7664939). Dental problems could result from abrasion or occupational injuries. Dental problems were reported among certain musicians, particularly wind instrumentalists. Radiation exposure could cause tooth, jaw and gum problems. Bleeding from gums was reported with high or low atmospheric pressures. Incisors of rats exposed to low pressures for 18 to 24 weeks showed mesenchymal changes that were augmented by concomitant exposure to cold. Superimposed heat counteracted these changes but produced ectodermal changes. Oral hygiene, proper working conditions and inclusion of dental and oral examinations in occupational health services were considered important."
1231350,Sumi and  Miyakawa 1990,Induction of Pituitary Tumors in Germ-Free Rats Exposed to Aspergillus versicolor,"Germ free rats monoassociated with Aspergillus-versicolor (A-versicolor) mold before birth and continually thereafter were used to clarify the role of the mold in tumorigenesis in the pituitary gland. Thirty three of 53 monoassociated germ free rats had pituitary tumors, while only three of 41 control germ free rats had such tumors. There was no neonatal mortality associated with exposure to A-versicolor. The first pituitary tumor of the experimental rats was observed in a female rat sacrificed on day 540. Most of the pituitary tumors were observed at final sacrifice. Ten cases of pituitary hyperplasia were noted in the experimental rats. Most of the adenomas were sharply circumscribed, demonstrating compression of surrounding normal tissue, while most of the hyperplasia were not sharply circumscribed. In the experimental rats pituitary adenoma was associated in five cases with parathyroid adenoma, three cases with islet cell adenoma, two cases with follicular adenoma of the thyroid, and one case with cortical adenoma of the adrenal. In two experimental cases pituitary adenoma was associated with both parathyroid and islet cell adenoma. In the germ free controls, none of the pituitary tumors were associated with other endocrine tumors. Chromic acid Schiff staining revealed the presence of mold spores in all of the lungs and the presence of mycelium in some of the intestinal tracts of treated cases, indicating mold infection. Lesions other than tumors in the experimental rats were characterized by many granulomas in the lung, nephron destruction in the kidney, necrosis in the liver, and fibrosis in the pancreas.","Induction of Pituitary Tumors in Germ-Free Rats Exposed to Aspergillus versicolor Abs: Germ free rats monoassociated with Aspergillus-versicolor (A-versicolor) mold before birth and continually thereafter were used to clarify the role of the mold in tumorigenesis in the pituitary gland. Thirty three of 53 monoassociated germ free rats had pituitary tumors, while only three of 41 control germ free rats had such tumors. There was no neonatal mortality associated with exposure to A-versicolor. The first pituitary tumor of the experimental rats was observed in a female rat sacrificed on day 540. Most of the pituitary tumors were observed at final sacrifice. Ten cases of pituitary hyperplasia were noted in the experimental rats. Most of the adenomas were sharply circumscribed, demonstrating compression of surrounding normal tissue, while most of the hyperplasia were not sharply circumscribed. In the experimental rats pituitary adenoma was associated in five cases with parathyroid adenoma, three cases with islet cell adenoma, two cases with follicular adenoma of the thyroid, and one case with cortical adenoma of the adrenal. In two experimental cases pituitary adenoma was associated with both parathyroid and islet cell adenoma. In the germ free controls, none of the pituitary tumors were associated with other endocrine tumors. Chromic acid Schiff staining revealed the presence of mold spores in all of the lungs and the presence of mycelium in some of the intestinal tracts of treated cases, indicating mold infection. Lesions other than tumors in the experimental rats were characterized by many granulomas in the lung, nephron destruction in the kidney, necrosis in the liver, and fibrosis in the pancreas."
1231349,Sanz et al. 1989,Nasal septum perforation in chromate-producing industry in Spain,"Nasal septum perforation and ulceration in workers employed in the chromate (13907454) producing industry was examined via a cross sectional study of 197 chrome (7440473) workers engaged in the production of chromates, bichromates, and chromic-acid (7738945) in Barcelona, Spain. Prevalence of perforations in those with chronic exposure was 31.4 percent (37 of 118 subjects), versus 4.3 percent (2 of 47) in those with intermittent exposure and 0 percent (0 of 32) in those with no exposure. Prevalence of ulcerations was 18.6 percent in those with chronic exposure, versus 14.9 percent in those with intermittent exposure and 0 percent in those with no exposure. Mean employment duration was approximately 18 years for all groups. The authors conclude that the prevalence of ulceration or perforation of the nasal septum is undoubtedly affected by the intensity and duration of exposure. The relatively high prevalence observed can be related to the toxic effects of chrome under poor environmental conditions.","Nasal septum perforation in chromate-producing industry in Spain Abs: Nasal septum perforation and ulceration in workers employed in the chromate (13907454) producing industry was examined via a cross sectional study of 197 chrome (7440473) workers engaged in the production of chromates, bichromates, and chromic-acid (7738945) in Barcelona, Spain. Prevalence of perforations in those with chronic exposure was 31.4 percent (37 of 118 subjects), versus 4.3 percent (2 of 47) in those with intermittent exposure and 0 percent (0 of 32) in those with no exposure. Prevalence of ulcerations was 18.6 percent in those with chronic exposure, versus 14.9 percent in those with intermittent exposure and 0 percent in those with no exposure. Mean employment duration was approximately 18 years for all groups. The authors conclude that the prevalence of ulceration or perforation of the nasal septum is undoubtedly affected by the intensity and duration of exposure. The relatively high prevalence observed can be related to the toxic effects of chrome under poor environmental conditions."
1231347,Burns and  Paterson 1989,Prompt Irrigation of Chemical Eye Injuries May Avert Severe Damage,"Causes and emergency treatment of chemical eye injuries were described. The possibility for injuries to occur to the eye may be present in many work locations. Alkali injuries have resulted from splashes with ammonia (7664417), used as a cleaning solution, in the manufacture of other chemicals, a fertilizer and a refrigerant; lye, used as a cleaner; lime or calcium-hydroxide (1305620), found in plaster, mortar and cement; potassium-hydroxide (1310583); and magnesium-hydroxide (1309428). Slightly less frequently damage has occurred from exposure to acidic substances such as sulfuric-acid (7664939) used in car batteries; sulfur-dioxide (7446095), used as a fruit and vegetable preservative and in bleach and refrigerants; hydrofluoric-acid (7664393); chromic-acid (1333820); hydrochloric-acid (7647010); nitric-acid (7697372); and acetic-acid (64197). Emergency care calls for copious irrigation of the external eye, keeping the eye open as much as possible during this process. A portable eye wash system should be available which will provide a continuous flushing of the eye during transport to an emergency care facility. The pH of the eye must return to normal before stopping the irrigation process. If necessary the eye can be irrigated with a dilute solution of EDTA to remove remaining particulates and return the pH to a normal range. Subsequent care depends on the severity of the injury.","Prompt Irrigation of Chemical Eye Injuries May Avert Severe Damage Abs: Causes and emergency treatment of chemical eye injuries were described. The possibility for injuries to occur to the eye may be present in many work locations. Alkali injuries have resulted from splashes with ammonia (7664417), used as a cleaning solution, in the manufacture of other chemicals, a fertilizer and a refrigerant; lye, used as a cleaner; lime or calcium-hydroxide (1305620), found in plaster, mortar and cement; potassium-hydroxide (1310583); and magnesium-hydroxide (1309428). Slightly less frequently damage has occurred from exposure to acidic substances such as sulfuric-acid (7664939) used in car batteries; sulfur-dioxide (7446095), used as a fruit and vegetable preservative and in bleach and refrigerants; hydrofluoric-acid (7664393); chromic-acid (1333820); hydrochloric-acid (7647010); nitric-acid (7697372); and acetic-acid (64197). Emergency care calls for copious irrigation of the external eye, keeping the eye open as much as possible during this process. A portable eye wash system should be available which will provide a continuous flushing of the eye during transport to an emergency care facility. The pH of the eye must return to normal before stopping the irrigation process. If necessary the eye can be irrigated with a dilute solution of EDTA to remove remaining particulates and return the pH to a normal range. Subsequent care depends on the severity of the injury."
1231346,Anonymous 1988,Chromium,"Following a brief discussion of the physical and chemical properties of chromium (7440473), this review considered the sources in the environment, environmental transport and distribution, environmental levels and human exposure, kinetics and metabolism, effects on organisms in the environment, effects on experimental animals and in-vitro test systems, effects on man, and an evaluation of the health risks for man. The main uses are in the metallurgical processing of ferrochromium and other metallurgical products, chiefly stainless steel, in the refractory processing of chrome bricks, and chemical processing to make chromic-acid and chromates. Occupational exposures can occur through the inhalation of metal dusts and fumes, and skin exposure. The effects on man were reviewed, including: the nutritional role of chromium; acute toxic effects; chronic toxic effects on the skin and mucous membrane, primary irritation of the skin, allergic contact dermatoses; effects on the lung such as bronchial irritation and sensitization; effects on the kidney; effects on the liver, gastrointestinal tract and circulatory system; teratogenicity; mutagenicity; carcinogenicity including lung cancer, cancer in other organs, and the relative risk between cancer risk and specific chromium compounds.","Chromium Abs: Following a brief discussion of the physical and chemical properties of chromium (7440473), this review considered the sources in the environment, environmental transport and distribution, environmental levels and human exposure, kinetics and metabolism, effects on organisms in the environment, effects on experimental animals and in-vitro test systems, effects on man, and an evaluation of the health risks for man. The main uses are in the metallurgical processing of ferrochromium and other metallurgical products, chiefly stainless steel, in the refractory processing of chrome bricks, and chemical processing to make chromic-acid and chromates. Occupational exposures can occur through the inhalation of metal dusts and fumes, and skin exposure. The effects on man were reviewed, including: the nutritional role of chromium; acute toxic effects; chronic toxic effects on the skin and mucous membrane, primary irritation of the skin, allergic contact dermatoses; effects on the lung such as bronchial irritation and sensitization; effects on the kidney; effects on the liver, gastrointestinal tract and circulatory system; teratogenicity; mutagenicity; carcinogenicity including lung cancer, cancer in other organs, and the relative risk between cancer risk and specific chromium compounds."
1231345,Anonymous 1986,"Soluble Hexavalent Chromium Compounds in Air. Colorimetric Field Method Using 1,5-Diphenylcarbazide","A colorimetric field method was described for the determination of soluble hexavalent chromium compounds in air using 1,5-diphenylcarbazide. Soluble hexavalent compounds include chromic-acid (1333820), chromic-acid-anhydride (1333820), and the chromates and dichromates of sodium, potassium, ammonium, and others. The use of protective clothing and need for proper ventilation systems were noted. Skin irritation, allergic contact dermatitis and nasal irritation have all been reported following exposures. In this method the soluble hexavalent chromium dust or mist is collected on an alkali treated PVC filter and extracted with 0.25 molar sulfuric-acid. The resultant solutions are then analyzed for hexavalent chromium by spectrophotometry (colorimetry), following the formation of a magenta chromogen by the addition of 0.15 percent 1,5-diphenylcarbazide in 1:1 water/acetone. The method was suitable for measurement periods from 1 to 8 hours. Vanadium was the only interferent, but under the conditions as given, this had little bearing. The lower analytical limit was 0.001 milligrams chromium/cubic meter for 120 liter samples of air.","Soluble Hexavalent Chromium Compounds in Air. Colorimetric Field Method Using 1,5-Diphenylcarbazide Abs: A colorimetric field method was described for the determination of soluble hexavalent chromium compounds in air using 1,5-diphenylcarbazide. Soluble hexavalent compounds include chromic-acid (1333820), chromic-acid-anhydride (1333820), and the chromates and dichromates of sodium, potassium, ammonium, and others. The use of protective clothing and need for proper ventilation systems were noted. Skin irritation, allergic contact dermatitis and nasal irritation have all been reported following exposures. In this method the soluble hexavalent chromium dust or mist is collected on an alkali treated PVC filter and extracted with 0.25 molar sulfuric-acid. The resultant solutions are then analyzed for hexavalent chromium by spectrophotometry (colorimetry), following the formation of a magenta chromogen by the addition of 0.15 percent 1,5-diphenylcarbazide in 1:1 water/acetone. The method was suitable for measurement periods from 1 to 8 hours. Vanadium was the only interferent, but under the conditions as given, this had little bearing. The lower analytical limit was 0.001 milligrams chromium/cubic meter for 120 liter samples of air."
1231343,Lenihan 1988,"Preliminary Survey Report: Control Technology for Gallium Arsenide Processing at Texas Instruments, Dallas, Texas, Report No. CT-163-16a","A study was conducted at Texas Instruments (SIC-3674), Dallas, Texas, to evaluate the technology currently available for controlling gallium-arsenide (1303000) (GaAs) dusts in the semiconductor industry. At this facility, GaAs optoelectronic devices were produced along with monolithic microwave integrated circuits and field effect transistors in low volume quantities. Hazardous chemicals used included methanol (67561), ammonia (7664417), silane (7803625), hydrochloric-acid (7647010), nitric-acid (7697372), hydrofluoric-acid (7664393), sulfuric-acid (7664939), chromic-acid (1333820), silicon-tetrafluoride (7783611), tellurium (13494809), and cadmium-telluride (1306258). A localized exhaust was being designed at this facility for cleaning crystal pullers. To clean the beryllium implanter saws, a dry bead blaster was employed. Chemical fume hoods were used in the production areas with 100 linear feet per minute being the minimum face velocity at 2 inches above the work surface. The minimum face velocity on the exhaust hoods for cleaning the ion implant source areas was 125 linear feet per minute. The coolant catch basin at the sawing or slicing operation for GaAs wafers was enclosed with a rubber skirting. A general summary of work practices, monitoring, and personal protective equipment was included. The author concludes that some useful control measures are employed at this facility for limiting the potential exposures.","Preliminary Survey Report: Control Technology for Gallium Arsenide Processing at Texas Instruments, Dallas, Texas, Report No. CT-163-16a Abs: A study was conducted at Texas Instruments (SIC-3674), Dallas, Texas, to evaluate the technology currently available for controlling gallium-arsenide (1303000) (GaAs) dusts in the semiconductor industry. At this facility, GaAs optoelectronic devices were produced along with monolithic microwave integrated circuits and field effect transistors in low volume quantities. Hazardous chemicals used included methanol (67561), ammonia (7664417), silane (7803625), hydrochloric-acid (7647010), nitric-acid (7697372), hydrofluoric-acid (7664393), sulfuric-acid (7664939), chromic-acid (1333820), silicon-tetrafluoride (7783611), tellurium (13494809), and cadmium-telluride (1306258). A localized exhaust was being designed at this facility for cleaning crystal pullers. To clean the beryllium implanter saws, a dry bead blaster was employed. Chemical fume hoods were used in the production areas with 100 linear feet per minute being the minimum face velocity at 2 inches above the work surface. The minimum face velocity on the exhaust hoods for cleaning the ion implant source areas was 125 linear feet per minute. The coolant catch basin at the sawing or slicing operation for GaAs wafers was enclosed with a rubber skirting. A general summary of work practices, monitoring, and personal protective equipment was included. The author concludes that some useful control measures are employed at this facility for limiting the potential exposures."
1231339,Santodonato et al. 1985,Monograph on Human Exposure to Chemicals in the Workplace: Chromic Acid,"This report summarizes and evaluates toxicologic information relevant to an occupational hazard assessment of chromic-acid (7738945), including chemical and physical properties, production and use, extent of occupational exposure, pharmacokinetics (absorption, distribution, metabolism, excretion), animal carcinogenicity and mutagenicity, and epidemiological studies. The wood preservation industry (SIC-2491) currently consumes about 20 percent of chromic-acid production. It is well known for producing skin ulceration, irritation, nasal septal perforation, and dermatitis. In chrome plating processes and anodizing by the electrolysis process, air concentrations are typically less than 50 micrograms/cubic meter (microg/m3). In air at chromated copper-arsenate production facilities surveys show air levels below 22microg/m3, and inside a building where wood preservatives are applied levels were at 0.3microg/m3. Animal studies have demonstrated that hexavalent chromium is absorbed rapidly across the lungs, but poorly from the gastrointestinal tract and skin. The trivalent state may accumulate in the spleen, liver, and bone marrow. Urine is the main route of excretion. Carcinogenicity has been indicated by intramuscular implantation of sintered chromium-trioxide (1333820) (chromic-acid), or by intrabronchial or subcutaneous implantation of various chromium salts in rats. Short term genotoxicity studies support these findings. Case reports and epidemiology studies have linked hexavalent chromium and increased cancer risk in humans. In the chromate production industry (SIC-2819), increased lung cancer risk is well documented.","Monograph on Human Exposure to Chemicals in the Workplace: Chromic Acid Abs: This report summarizes and evaluates toxicologic information relevant to an occupational hazard assessment of chromic-acid (7738945), including chemical and physical properties, production and use, extent of occupational exposure, pharmacokinetics (absorption, distribution, metabolism, excretion), animal carcinogenicity and mutagenicity, and epidemiological studies. The wood preservation industry (SIC-2491) currently consumes about 20 percent of chromic-acid production. It is well known for producing skin ulceration, irritation, nasal septal perforation, and dermatitis. In chrome plating processes and anodizing by the electrolysis process, air concentrations are typically less than 50 micrograms/cubic meter (microg/m3). In air at chromated copper-arsenate production facilities surveys show air levels below 22microg/m3, and inside a building where wood preservatives are applied levels were at 0.3microg/m3. Animal studies have demonstrated that hexavalent chromium is absorbed rapidly across the lungs, but poorly from the gastrointestinal tract and skin. The trivalent state may accumulate in the spleen, liver, and bone marrow. Urine is the main route of excretion. Carcinogenicity has been indicated by intramuscular implantation of sintered chromium-trioxide (1333820) (chromic-acid), or by intrabronchial or subcutaneous implantation of various chromium salts in rats. Short term genotoxicity studies support these findings. Case reports and epidemiology studies have linked hexavalent chromium and increased cancer risk in humans. In the chromate production industry (SIC-2819), increased lung cancer risk is well documented."
1231338,Rondia and  Closset 1985,Aerosol Versus Solution Composition In Occupational Exposures,"The composition of aerosols generated in workrooms where gas bubbles or liquid drops arise from solutions containing inorganic salts or acids was studied. In one factory, a solution of zinc-sulfate (7733020) in dilute sulfuric-acid (7664939) was electrolyzed to yield thick zinc (7440666) sheets of high purity. In a second factory, a steel foundry, aerosol was generated from metal coating operations involving chromic-acid (13530682) and phosphoric-acid (7664382) pickling solutions. The composition and concentration of the zinc aerosol were investigated by sampling for 1 to 3 days at a height of 1.5 meters between rows of 33 pits. Hydrogen bubbles escaping from the zinc solution formed a permanent aerosol above the pits. Particles were collected and washed with distilled water. The resulting solutions were analyzed by atomic absorption spectrophotometry, turbidimetry, and titrimetry. Particle diameters were measured. Operations in the surface treatment shop for steel consisted of chromium (7440473) plating, electropolishing, anodization, and phosphatation. The composition and concentration of aerosols were determined. The distribution of aerosols near the tanks was not homogeneous for each constituent in the various diameter classes. The bursting of the hydrogen micro bubbles at the surface of the zinc-sulfate solution yielded an aerosol of mostly large particles with a composition not fully comparable with the composition of the solution. The acidity/sulfate ratio decreased with particle diameter and the zinc/sulfate and manganese (7439965) sulfate ratios increased. The composition and concentration of aerosols in the steel foundry were not homogeneous for liquid constituents. Chromate (11104599) was more abundant in larger particles, whereas small particles contained more of the sulfate and phosphate particles. The authors conclude that further study is needed to verify the mechanism of aerosol formation from solutions.","Aerosol Versus Solution Composition In Occupational Exposures Abs: The composition of aerosols generated in workrooms where gas bubbles or liquid drops arise from solutions containing inorganic salts or acids was studied. In one factory, a solution of zinc-sulfate (7733020) in dilute sulfuric-acid (7664939) was electrolyzed to yield thick zinc (7440666) sheets of high purity. In a second factory, a steel foundry, aerosol was generated from metal coating operations involving chromic-acid (13530682) and phosphoric-acid (7664382) pickling solutions. The composition and concentration of the zinc aerosol were investigated by sampling for 1 to 3 days at a height of 1.5 meters between rows of 33 pits. Hydrogen bubbles escaping from the zinc solution formed a permanent aerosol above the pits. Particles were collected and washed with distilled water. The resulting solutions were analyzed by atomic absorption spectrophotometry, turbidimetry, and titrimetry. Particle diameters were measured. Operations in the surface treatment shop for steel consisted of chromium (7440473) plating, electropolishing, anodization, and phosphatation. The composition and concentration of aerosols were determined. The distribution of aerosols near the tanks was not homogeneous for each constituent in the various diameter classes. The bursting of the hydrogen micro bubbles at the surface of the zinc-sulfate solution yielded an aerosol of mostly large particles with a composition not fully comparable with the composition of the solution. The acidity/sulfate ratio decreased with particle diameter and the zinc/sulfate and manganese (7439965) sulfate ratios increased. The composition and concentration of aerosols in the steel foundry were not homogeneous for liquid constituents. Chromate (11104599) was more abundant in larger particles, whereas small particles contained more of the sulfate and phosphate particles. The authors conclude that further study is needed to verify the mechanism of aerosol formation from solutions."
1231337,Mcbee et al. 1985,Industrial Evaluation Of Sulfur Concrete In Corrosive Environments,"The use of sulfur (7704349) concrete in corrosive environments is reviewed. A sulfur concrete technology has been developed by the United States Bureau of Mines. The orginal impetus for the program was to develop new uses for sulfur and to utilize an anticipated surplus of sulfur. Modified sulfur cements are discussed. Such cements are prepared by reacting sulfur and dicyclopentadiene (77736) and cyclopentadiene oligomers. The sulfur is stabilized and may be used in the liquid state or solidified and flaked for later use. Modified sulfur concrete is discussed. The concretes are prepared by hot mixing sulfur cement with aggregates such as quartz (14808607) or limestone (1317653). Sulfur concretes prepared with quartz are acid resistant and concretes prepared with limestone are salt resistant. Modified sulfur concretes attain about 80 percent of their mechanical strength in 1 day and full strength in about 6 months. Installation of sulfur concrete is considered. Evaluation of modified sulfur concrete in industrial settings is discussed. Sulfur concretes have been tested under actual operating conditions in 50 corrosive environments at 40 commercial facilities over a 4 year period. The concretes showed no significant signs of strength loss or degradation, although minor degradation occurred in materials exposed to sodium-hydroxide (1310732), hot chromic-acid (13530682), and copper (7440508) slimes. Regular concrete materials were attacked and, in some cases, destroyed under the same conditions. Industrial testing of sulfur concretes is continuing to establish their durability and longevity. Sulfur concretes should find widespread application as replacements for materials that fail in acid and salt environments.","Industrial Evaluation Of Sulfur Concrete In Corrosive Environments Abs: The use of sulfur (7704349) concrete in corrosive environments is reviewed. A sulfur concrete technology has been developed by the United States Bureau of Mines. The orginal impetus for the program was to develop new uses for sulfur and to utilize an anticipated surplus of sulfur. Modified sulfur cements are discussed. Such cements are prepared by reacting sulfur and dicyclopentadiene (77736) and cyclopentadiene oligomers. The sulfur is stabilized and may be used in the liquid state or solidified and flaked for later use. Modified sulfur concrete is discussed. The concretes are prepared by hot mixing sulfur cement with aggregates such as quartz (14808607) or limestone (1317653). Sulfur concretes prepared with quartz are acid resistant and concretes prepared with limestone are salt resistant. Modified sulfur concretes attain about 80 percent of their mechanical strength in 1 day and full strength in about 6 months. Installation of sulfur concrete is considered. Evaluation of modified sulfur concrete in industrial settings is discussed. Sulfur concretes have been tested under actual operating conditions in 50 corrosive environments at 40 commercial facilities over a 4 year period. The concretes showed no significant signs of strength loss or degradation, although minor degradation occurred in materials exposed to sodium-hydroxide (1310732), hot chromic-acid (13530682), and copper (7440508) slimes. Regular concrete materials were attacked and, in some cases, destroyed under the same conditions. Industrial testing of sulfur concretes is continuing to establish their durability and longevity. Sulfur concretes should find widespread application as replacements for materials that fail in acid and salt environments."
1231336,Mihlan and  Willson 1984,"Preliminary Control Technology Survey Report No. CT-115-26a, Micro Power Systems, Inc., Santa Clara, California","A survey to assess control technology was conducted at Micro Power Systems, Incorporated (SIC-3674), Santa Clara, California, in January, 1982. Engineering controls included isolation, shielding, and local exhaust ventilation. Isolation was used in plasma etching, ion implantation, chemical vapor deposition, epitaxial silicon deposition, and metalization processes. Shielding was used in the ion implantation units to limit X-ray emissions, in plasma etching and epitaxial silicon deposition to control radiofrequency radiation emissions, and in substrate exposure to limit ultraviolet emissions. Local exhaust ventilation was used in wet chemical cleaning and etching, in photolithography processes, and in the diffusion furnaces. The electron beam evaporation, direct current sputtering, plasma etching, ion implantation, and chemical vapor and epitaxial silicon deposition processes were automated. Personal protective equipment used included safety glasses, face shields, acid resistant coveralls, and gloves. The facility had a health and safety program that included worker training in safety, materials handling, personal protective equipment, and hazard reporting. The facility retained consultants in industrial hygiene, safety, and health care. Recommendations include establishing a program of preplacement and periodic medical examinations and evaluation of the ability of the ventilation system to control chromic-acid (7738945), phenol (108952), and antimony-trioxide (1309644).","Preliminary Control Technology Survey Report No. CT-115-26a, Micro Power Systems, Inc., Santa Clara, California Abs: A survey to assess control technology was conducted at Micro Power Systems, Incorporated (SIC-3674), Santa Clara, California, in January, 1982. Engineering controls included isolation, shielding, and local exhaust ventilation. Isolation was used in plasma etching, ion implantation, chemical vapor deposition, epitaxial silicon deposition, and metalization processes. Shielding was used in the ion implantation units to limit X-ray emissions, in plasma etching and epitaxial silicon deposition to control radiofrequency radiation emissions, and in substrate exposure to limit ultraviolet emissions. Local exhaust ventilation was used in wet chemical cleaning and etching, in photolithography processes, and in the diffusion furnaces. The electron beam evaporation, direct current sputtering, plasma etching, ion implantation, and chemical vapor and epitaxial silicon deposition processes were automated. Personal protective equipment used included safety glasses, face shields, acid resistant coveralls, and gloves. The facility had a health and safety program that included worker training in safety, materials handling, personal protective equipment, and hazard reporting. The facility retained consultants in industrial hygiene, safety, and health care. Recommendations include establishing a program of preplacement and periodic medical examinations and evaluation of the ability of the ventilation system to control chromic-acid (7738945), phenol (108952), and antimony-trioxide (1309644)."
1231335,Franchini et al. 1984,Chromium,"Occupational exposure to chromium (7440473) was reviewed with regard to industrial uses, biological effects, and assessment of exposure. Chromium toxicity is primarily attributable to hexavalent and not trivalent compounds. Sources of chromium exposure to workers were identified as chromic-acid (7738945) mists and fumes during electroplating and welding, and pigment production dusts containing sodium-dichromate (10588019), potassium-chromate (7789006), and water soluble chromium(III)-sulfate (10101538). Lesions from prolonged exposure have been found to affect the skin, the respiratory tract, and the digestive system and include chronic ulcers, irritative and eczematous dermatitis, atrophy and hypertrophy of the nasal mucosa, chronic bronchitis, bronchial asthma, and gastroenterocolitis. An association between exposure to chromium(VI) (18540299) and cancer has been demonstrated. The primary biological indicator for assessment of chromium exposure is urinary chromium, measured on spot samples and adjusted for creatinine concentration or corrected to constant specific gravity. Total urinary chromium values yield current and past exposures, and the adjusted values are used to determine recent exposure. Other topics discussed included chemical and physical properties, metabolism, research needs, and guidelines for urinary chromium evaluation in field surveys.","Chromium Abs: Occupational exposure to chromium (7440473) was reviewed with regard to industrial uses, biological effects, and assessment of exposure. Chromium toxicity is primarily attributable to hexavalent and not trivalent compounds. Sources of chromium exposure to workers were identified as chromic-acid (7738945) mists and fumes during electroplating and welding, and pigment production dusts containing sodium-dichromate (10588019), potassium-chromate (7789006), and water soluble chromium(III)-sulfate (10101538). Lesions from prolonged exposure have been found to affect the skin, the respiratory tract, and the digestive system and include chronic ulcers, irritative and eczematous dermatitis, atrophy and hypertrophy of the nasal mucosa, chronic bronchitis, bronchial asthma, and gastroenterocolitis. An association between exposure to chromium(VI) (18540299) and cancer has been demonstrated. The primary biological indicator for assessment of chromium exposure is urinary chromium, measured on spot samples and adjusted for creatinine concentration or corrected to constant specific gravity. Total urinary chromium values yield current and past exposures, and the adjusted values are used to determine recent exposure. Other topics discussed included chemical and physical properties, metabolism, research needs, and guidelines for urinary chromium evaluation in field surveys."
1231333,Syrovadko 1983,Oxidising substances,"The toxicity and health hazards of oxidizing substances are reviewed. Oxidizing substances react with other compounds by simultaneously giving off electrons and undergoing a reduction. Oxidizing substances are divided into neutral substances such as ozone (10028156), lead-oxide (1335257), and nitrotoluene (1321126); alkaline substances such as potassium-permanganate (7722647) and oxygen (7782447); and acids such as chromic-acid (13530682), nitric-acid (7697372) and sulfuric-acid (7664939). The intensity of the action of oxidizing agents is related to their oxidizing/reducing potential. The production and industrial uses of oxidizing substances present a potential health hazard for the work force. The corrosive properties of acid oxidizing substances make them hazardous to humans and equipment; pipe connections, jackets, and packing become susceptible to corrosion that results in leaks. Most oxidizing agents are highly toxic. The acid compounds are irritants and give out asphyxiating fumes. Some oxidizers such as sulfuric-acid exert an effect on the gastrointestinal tract; manganese (7439965), chromium (7440473), and lead (7439921) cause diseases of the central nervous system such as Parkinsonism and of the lungs such as pneumoconiosis and pneumonitis. Serious cases of chronic lead poisoning may be encountered in industry. The most radical preventive measure is the rationalization of production processes. The author concludes that use of protective equipment such as acid proof protective clothing, footwear, gloves, and goggles may reduce exposure and hence the hazards caused by oxidizers.","Oxidising substances Abs: The toxicity and health hazards of oxidizing substances are reviewed. Oxidizing substances react with other compounds by simultaneously giving off electrons and undergoing a reduction. Oxidizing substances are divided into neutral substances such as ozone (10028156), lead-oxide (1335257), and nitrotoluene (1321126); alkaline substances such as potassium-permanganate (7722647) and oxygen (7782447); and acids such as chromic-acid (13530682), nitric-acid (7697372) and sulfuric-acid (7664939). The intensity of the action of oxidizing agents is related to their oxidizing/reducing potential. The production and industrial uses of oxidizing substances present a potential health hazard for the work force. The corrosive properties of acid oxidizing substances make them hazardous to humans and equipment; pipe connections, jackets, and packing become susceptible to corrosion that results in leaks. Most oxidizing agents are highly toxic. The acid compounds are irritants and give out asphyxiating fumes. Some oxidizers such as sulfuric-acid exert an effect on the gastrointestinal tract; manganese (7439965), chromium (7440473), and lead (7439921) cause diseases of the central nervous system such as Parkinsonism and of the lungs such as pneumoconiosis and pneumonitis. Serious cases of chronic lead poisoning may be encountered in industry. The most radical preventive measure is the rationalization of production processes. The author concludes that use of protective equipment such as acid proof protective clothing, footwear, gloves, and goggles may reduce exposure and hence the hazards caused by oxidizers."
1231327,Almaguer and  Kramkowski 1983,"Health hazard evaluation report no. HETA-82-116-1319, Modine Manufacturing, McHenry, Illinois","Environmental and breathing zone samples were analyzed for chromic-acid (7738945) and zinc (7440666) at the Modine Manufacturing Company (SIC-3479), McHenry, Illinois in March and May 1982. The request for an evaluation was made by an employee representative on suspicion of illness associated with the chrome dipping operation. Breathing zone samples showed 0.7 micrograms per cubic meter chromic-acid as hexavalent-chromium (18540299) (Cr-VI). The current NIOSH standard for Cr-VI is 1 microgram per cubic meter. Zinc chromates were not found in the air samples. Spot tests showed Cr-VI contamination throughout the dipping and buffing operations. Confidential medical questionnaires were given to seven employees working in the dipping operation. One case of dermatitis and numerous complaints of mucous membrane irritation, nausea, and lightheadedness were reported. The authors conclude that a health hazard did not exist due to airborne Cr-VI compounds or zinc chromates. A potential hazard did exist due to poor handling of the dip solution. Good personal hygiene and improved work practices are recommended.","Health hazard evaluation report no. HETA-82-116-1319, Modine Manufacturing, McHenry, Illinois Abs: Environmental and breathing zone samples were analyzed for chromic-acid (7738945) and zinc (7440666) at the Modine Manufacturing Company (SIC-3479), McHenry, Illinois in March and May 1982. The request for an evaluation was made by an employee representative on suspicion of illness associated with the chrome dipping operation. Breathing zone samples showed 0.7 micrograms per cubic meter chromic-acid as hexavalent-chromium (18540299) (Cr-VI). The current NIOSH standard for Cr-VI is 1 microgram per cubic meter. Zinc chromates were not found in the air samples. Spot tests showed Cr-VI contamination throughout the dipping and buffing operations. Confidential medical questionnaires were given to seven employees working in the dipping operation. One case of dermatitis and numerous complaints of mucous membrane irritation, nausea, and lightheadedness were reported. The authors conclude that a health hazard did not exist due to airborne Cr-VI compounds or zinc chromates. A potential hazard did exist due to poor handling of the dip solution. Good personal hygiene and improved work practices are recommended."
1231326,White et al. 1983,"Health hazard evaluation report no. HETA-77-011-1338, Inland Division, GMC, Dayton, Ohio","Worker exposures to wet rubber process chemicals were surveyed in February, July and October, 1977 and March, 1982 at the Inland Division of General Motors Corporation (SIC-3060) in Dayton, Ohio. The evaluation was requested by the United Rubber, Cork and Linoleum Workers, Local 87, on behalf of 600 workers concerned about skin and respiratory problems. Air sampling for organic vapors was conducted and workers completed medical questionnaires. Medical examinations, and medical records were reviewed. Exposures to 1,1,1-trichloroethane (71556), toluene (108883), trichloroethylene (79016), para-xylene (106423), o-xylene (95476), ammonia (7664417), ethyl-benzene (100414), total particulates, 2-ethoxyethanol (110805), isopropanol (67630), n-butyl-acetate (123864), and isobutylbutyrate (539902), were below acceptable OSHA standards. Twelve of 162 workers examined had active, healed, or healing skin rashes of potential occupational origin. Respiratory function tests did not identify any specific jobs or agents associated with impaired function, however four individuals with possible job related respiratory impairments were found. The authors conclude that no chemical exposure hazards exist at this facility. They recommend adherence to good personal and work hygiene practices, development of employee health and safety education programs, establishment of a safe vessel entry program, enclosure of the ammonia metering system, and isolation of the chromic-acid transfer lines.","Health hazard evaluation report no. HETA-77-011-1338, Inland Division, GMC, Dayton, Ohio Abs: Worker exposures to wet rubber process chemicals were surveyed in February, July and October, 1977 and March, 1982 at the Inland Division of General Motors Corporation (SIC-3060) in Dayton, Ohio. The evaluation was requested by the United Rubber, Cork and Linoleum Workers, Local 87, on behalf of 600 workers concerned about skin and respiratory problems. Air sampling for organic vapors was conducted and workers completed medical questionnaires. Medical examinations, and medical records were reviewed. Exposures to 1,1,1-trichloroethane (71556), toluene (108883), trichloroethylene (79016), para-xylene (106423), o-xylene (95476), ammonia (7664417), ethyl-benzene (100414), total particulates, 2-ethoxyethanol (110805), isopropanol (67630), n-butyl-acetate (123864), and isobutylbutyrate (539902), were below acceptable OSHA standards. Twelve of 162 workers examined had active, healed, or healing skin rashes of potential occupational origin. Respiratory function tests did not identify any specific jobs or agents associated with impaired function, however four individuals with possible job related respiratory impairments were found. The authors conclude that no chemical exposure hazards exist at this facility. They recommend adherence to good personal and work hygiene practices, development of employee health and safety education programs, establishment of a safe vessel entry program, enclosure of the ammonia metering system, and isolation of the chromic-acid transfer lines."
1231324,Choen and  Kramkowski 1974,Chromic Acid in Electroplating,"Investigations were conducted to determine the hazards facing workers in the electroplating industry. A review of the literature on chromic-acid (1333820) revealed five previous studies where an attempt was made to correlate exposure to effect. Each of these earlier studies determined levels of chromic-acid which were higher than those found in the current study. The results of medical examinations for the present study group indicated 35 of 37 (95%) workers in the chrome plating area had developed damage to the tissues in their noses, while a lesser number had developed skin damage. Workers employed for longer periods of time had developed higher grade lesions of the nasal mucosae. All except one worker in the comparison group had perfectly normal nasal tissue with no evidence of any damage. Environmental levels of chromic-acid in the work areas were very low, far too low to explain the medical findings using the current criteria. Observation of the workers indicated that the transfer of chromic-acid from work surfaces to nasal tissues may have been a significant factor. The authors suggest a reevaluation of the current restrictions of levels of chromic-acid may be in order based on these findings.","Chromic Acid in Electroplating Abs: Investigations were conducted to determine the hazards facing workers in the electroplating industry. A review of the literature on chromic-acid (1333820) revealed five previous studies where an attempt was made to correlate exposure to effect. Each of these earlier studies determined levels of chromic-acid which were higher than those found in the current study. The results of medical examinations for the present study group indicated 35 of 37 (95%) workers in the chrome plating area had developed damage to the tissues in their noses, while a lesser number had developed skin damage. Workers employed for longer periods of time had developed higher grade lesions of the nasal mucosae. All except one worker in the comparison group had perfectly normal nasal tissue with no evidence of any damage. Environmental levels of chromic-acid in the work areas were very low, far too low to explain the medical findings using the current criteria. Observation of the workers indicated that the transfer of chromic-acid from work surfaces to nasal tissues may have been a significant factor. The authors suggest a reevaluation of the current restrictions of levels of chromic-acid may be in order based on these findings."
1231323,Boeniger 1979,"Industrial Hygiene Survey Report at R. R. Donnelley Printing Company, Lancaster, Pennsylvania, Report No. IWS-077-34","A visit was made to the R. R. Donnelley Printing Company, Lancaster, Pennsylvania for the purpose of conducting an industrial hygiene survey of the facility including air sampling of ink mists, paper dust and carbon-monoxide (630080) (CO). The facility was constructed in 1972 and has been in continuous use as a web fed letterpress shop printing telephone books. The company employed about 70 pressmen, 100 bindery personnel and 15 plate makers. Ink mist concentrations at control panels ranged from 1.3 to 1.7mg/m3. The airborne exposure to respirable particles of carbon-black (1333864) was less than 0.05mg/m3 and to mineral-oil was less than 0.3 mg/m3. The author recommends that minimization of exposure to printing ink mist be continued. Periodic monitoring of the chromic-acid (1333820) plating tank should be done. Paper dust exposures, which they did not exceed current limits, should be lessened through improved ventilation or short term use of respirators.","Industrial Hygiene Survey Report at R. R. Donnelley Printing Company, Lancaster, Pennsylvania, Report No. IWS-077-34 Abs: A visit was made to the R. R. Donnelley Printing Company, Lancaster, Pennsylvania for the purpose of conducting an industrial hygiene survey of the facility including air sampling of ink mists, paper dust and carbon-monoxide (630080) (CO). The facility was constructed in 1972 and has been in continuous use as a web fed letterpress shop printing telephone books. The company employed about 70 pressmen, 100 bindery personnel and 15 plate makers. Ink mist concentrations at control panels ranged from 1.3 to 1.7mg/m3. The airborne exposure to respirable particles of carbon-black (1333864) was less than 0.05mg/m3 and to mineral-oil was less than 0.3 mg/m3. The author recommends that minimization of exposure to printing ink mist be continued. Periodic monitoring of the chromic-acid (1333820) plating tank should be done. Paper dust exposures, which they did not exceed current limits, should be lessened through improved ventilation or short term use of respirators."
1231321,Sheehy 1982,"Preliminary Control Technology Assessment of TWA Maintenance Facility, Kansas City, Missouri, Report No. CT-106-18a","An on site visit was made to the TWA Maintenance Facility (SIC-3471), Kansas City, Missouri for the purpose of evaluating methods used to control worker exposures to hazardous materials. Electroplating operations were housed in a large brick building at the site and the processes used include silver cyanide, copper cyanide, cadmium cyanide, and chromic-acid (1333820) baths. Cleaning and stripping operations include perchloroethylene (127184) degreasers, sulfuric-acid (7664939), nitric-acid (7697372), hydrochloric-acid (7647010) and caustic solutions, and nickel cyanide strip. Most of the plating and cleaning tanks were equipped with local exhaust ventilation. Four of the chrome tanks also had sliding covers. Local exhaust systems vented from three sides of the tanks and exhausted downward through an exhaust tunnel in the floor of the building. An electrically operated roll up cover was attached to the perchloroethylene degreaser along with a refrigerator chiller. A large make up air unit supplied air to the plating shop. Face shields, respirators and other safety equipment was available. A nurse was on duty at all times and the industrial hygiene concerns of the facility were handled by two full time persons. The authors recommend this shop for a detailed survey because of the number of potentially hazardous operations.","Preliminary Control Technology Assessment of TWA Maintenance Facility, Kansas City, Missouri, Report No. CT-106-18a Abs: An on site visit was made to the TWA Maintenance Facility (SIC-3471), Kansas City, Missouri for the purpose of evaluating methods used to control worker exposures to hazardous materials. Electroplating operations were housed in a large brick building at the site and the processes used include silver cyanide, copper cyanide, cadmium cyanide, and chromic-acid (1333820) baths. Cleaning and stripping operations include perchloroethylene (127184) degreasers, sulfuric-acid (7664939), nitric-acid (7697372), hydrochloric-acid (7647010) and caustic solutions, and nickel cyanide strip. Most of the plating and cleaning tanks were equipped with local exhaust ventilation. Four of the chrome tanks also had sliding covers. Local exhaust systems vented from three sides of the tanks and exhausted downward through an exhaust tunnel in the floor of the building. An electrically operated roll up cover was attached to the perchloroethylene degreaser along with a refrigerator chiller. A large make up air unit supplied air to the plating shop. Face shields, respirators and other safety equipment was available. A nurse was on duty at all times and the industrial hygiene concerns of the facility were handled by two full time persons. The authors recommend this shop for a detailed survey because of the number of potentially hazardous operations."
1231320,Spottswood 1981,"Preliminary Control Technology Assessment of Advance Plating Company, Ft. Worth, Texas, Report No. CT-106-20a","A walk through survey was made at Advance Plating Company, Ft. Worth, Texas, to evaluate the control methods in place at this facility. The company was engaged in decorative chrome plating of automobile and truck parts and welded wire products. A buffing and polishing operation was also run within the facility. There was one plating line with two nickel tanks, one chromium tank, two pretreatment tanks, and several rinse tanks. Engineering controls at this facility included general dilution ventilation with doors open for all but 2 months of the year. A 5 foot window exhaust fan was in operation at the time of the visit. Four other fans were used for air cooling. A mist suppressant was used to control chromic-acid (1333820) mists. Safety glasses and a paper dust mask were used by the polisher. No other protective equipment was used at the facility. Five persons were employed at this site, only one of whom was a polisher. The author does not recommend this site for an in depth control technology study, unless there is some future interest in evaluation of mist suppressants.","Preliminary Control Technology Assessment of Advance Plating Company, Ft. Worth, Texas, Report No. CT-106-20a Abs: A walk through survey was made at Advance Plating Company, Ft. Worth, Texas, to evaluate the control methods in place at this facility. The company was engaged in decorative chrome plating of automobile and truck parts and welded wire products. A buffing and polishing operation was also run within the facility. There was one plating line with two nickel tanks, one chromium tank, two pretreatment tanks, and several rinse tanks. Engineering controls at this facility included general dilution ventilation with doors open for all but 2 months of the year. A 5 foot window exhaust fan was in operation at the time of the visit. Four other fans were used for air cooling. A mist suppressant was used to control chromic-acid (1333820) mists. Safety glasses and a paper dust mask were used by the polisher. No other protective equipment was used at the facility. Five persons were employed at this site, only one of whom was a polisher. The author does not recommend this site for an in depth control technology study, unless there is some future interest in evaluation of mist suppressants."
1231319,Anonymous 1981,Chromium and Inorganic Compounds of Chromium in Air. Laboratory Method Using Atomic Absorption Spectrometry,"An analytical method was described for the detection of airborne chromium (7440473), oxides of chromium, soluble and insoluble salts, and chromic-acid (1333820) in the workplace atmosphere. Sampling periods run for 15 minutes to 8 hours. The method cannot distinguish between hexavalent chromium and chromium in other valence states. The sample is collected on a filter which is then treated with 50 percent nitric-acid containing hydrogen-peroxide. Atomic absorption spectrometry is used to analyze the resulting solution. It is recommended that the measurements be made at a wavelength of 357.9 nanometers without background correction. Sensitivity for chromium was 0.04 microgram/milliliter. The detection limit was 0.003mg/m3 for 30 liters of air. Cobalt, iron and nickel may suppress chromium atomic absorption; interference may also be caused by copper, barium, aluminum, calcium, and magnesium. A nitrous oxide/acetylene flame should be used when it is suspected that these other cations are present. A significant error may result from choosing the inappropriate sample volume.","Chromium and Inorganic Compounds of Chromium in Air. Laboratory Method Using Atomic Absorption Spectrometry Abs: An analytical method was described for the detection of airborne chromium (7440473), oxides of chromium, soluble and insoluble salts, and chromic-acid (1333820) in the workplace atmosphere. Sampling periods run for 15 minutes to 8 hours. The method cannot distinguish between hexavalent chromium and chromium in other valence states. The sample is collected on a filter which is then treated with 50 percent nitric-acid containing hydrogen-peroxide. Atomic absorption spectrometry is used to analyze the resulting solution. It is recommended that the measurements be made at a wavelength of 357.9 nanometers without background correction. Sensitivity for chromium was 0.04 microgram/milliliter. The detection limit was 0.003mg/m3 for 30 liters of air. Cobalt, iron and nickel may suppress chromium atomic absorption; interference may also be caused by copper, barium, aluminum, calcium, and magnesium. A nitrous oxide/acetylene flame should be used when it is suspected that these other cations are present. A significant error may result from choosing the inappropriate sample volume."
1231318,Sheehy 1982,"In-Depth Survey Report of Sodus Hardchrome, Inc., Sodus, Michigan, Report No. CT-106-13a","An in depth survey of possible occupational hazards was made at Sodus Hardchrome Inc. (SIC-3471), Sodus, Michigan. At this facility hardchrome plating of high tensile strength steel parts was carried out. These parts, including hydraulic cylinders ranging in size from 5 inches to 28 feet long, were used in construction, materials handling, and other heavy equipment. Plating solutions contain 28 ounces/gallon of chromic-acid (1333820) and were maintained at 130 to 140 degrees-F. All of the plating tanks had push/pull ventilation systems. The primary hazards to the workers arose from chromic-acid and sulfuric-acid (7664939) exposures. Personal and area air samples were collected for 3 consecutive days. Mean concentrations for all eight personal samples was 0.004mg/m3 for chromium-VI (18540299) and 0.2mg/m3 for sulfuric-acid. Area samples for total chromium ranged from less than 0.007mg/m3 to 0.057mg/m3. Sulfuric-acid concentrations ranged from 0.2 to 0.7mg/m3. These findings indicated that the chemical hazards were effectively controlled. When examining individual tanks in the process, it was determined that the control of hexavalent chromium emissions for tank 5 could be improved by increasing the exhaust rate and exercising more caution in rinsing chromic-acid off the plated parts.","In-Depth Survey Report of Sodus Hardchrome, Inc., Sodus, Michigan, Report No. CT-106-13a Abs: An in depth survey of possible occupational hazards was made at Sodus Hardchrome Inc. (SIC-3471), Sodus, Michigan. At this facility hardchrome plating of high tensile strength steel parts was carried out. These parts, including hydraulic cylinders ranging in size from 5 inches to 28 feet long, were used in construction, materials handling, and other heavy equipment. Plating solutions contain 28 ounces/gallon of chromic-acid (1333820) and were maintained at 130 to 140 degrees-F. All of the plating tanks had push/pull ventilation systems. The primary hazards to the workers arose from chromic-acid and sulfuric-acid (7664939) exposures. Personal and area air samples were collected for 3 consecutive days. Mean concentrations for all eight personal samples was 0.004mg/m3 for chromium-VI (18540299) and 0.2mg/m3 for sulfuric-acid. Area samples for total chromium ranged from less than 0.007mg/m3 to 0.057mg/m3. Sulfuric-acid concentrations ranged from 0.2 to 0.7mg/m3. These findings indicated that the chemical hazards were effectively controlled. When examining individual tanks in the process, it was determined that the control of hexavalent chromium emissions for tank 5 could be improved by increasing the exhaust rate and exercising more caution in rinsing chromic-acid off the plated parts."
1231317,Mcmahon et al. 1981,New Technology For Personal Sampling Of NO2 And NOx In The Workplace,"A personal sampler for measurement of occupational exposures to nitrogen-dioxide (10102440) and nitric-oxide (10102439) was developed. Constructed of polypropylene, the tubular sampler was small, light weight, unbreakable, and easily worn in the breathing zone. Samplers were designed to be worn with the exposed, open end facing down so that dust or particulate matter could not enter. Passive collection of nitric-oxide was performed by molecular diffusion and subsequent trapping of the molecules onto matrices coated with triethanolamine (TEA) at the closed end of the sampler. A chromic-acid disc was inserted behind the TEA coated screens in the sampler. The disc oxidized nitric-oxide to nitrogen-dioxide which then back diffused and was trapped on the TEA coated screens. Samples were analyzed up to 1 month after exposure by adding a 1.0 milliliter aliquot of azo dye reagent to the sampler, transferring the sample to a cuvette, and reading the transmittance of the resulting colored solution with a specially designed colorimeter. The colorimeter was designed to convert transmittance percent to absorbance and to derive a nanomole nitrogen-dioxide value for each sampler analyzed. The sensitivity range for the colorimeter was 0 to 20 parts per million (ppm). After use, the samplers were recycled by being washed and reloaded with fresh TEA coated screens and chromic-acid discs. Personal samplers and the colorimeter were contained in a complete kit designed for use in the field. Samplers were exposed in the laboratory to incrementally increased nitrogen-dioxide doses from 0 to 55ppm and analyzed 1 day later. Nitrogen-dioxide collection efficiency was linear and had an accuracy of approximately 10 percent for any given concentration. The authors conclude that this personal monitoring system with a designated colorimeter allows efficient collection and accurate monitoring of individual exposures to nitrogen-dioxide or nitric-oxide during a complete 8 hour work shift.","New Technology For Personal Sampling Of NO2 And NOx In The Workplace Abs: A personal sampler for measurement of occupational exposures to nitrogen-dioxide (10102440) and nitric-oxide (10102439) was developed. Constructed of polypropylene, the tubular sampler was small, light weight, unbreakable, and easily worn in the breathing zone. Samplers were designed to be worn with the exposed, open end facing down so that dust or particulate matter could not enter. Passive collection of nitric-oxide was performed by molecular diffusion and subsequent trapping of the molecules onto matrices coated with triethanolamine (TEA) at the closed end of the sampler. A chromic-acid disc was inserted behind the TEA coated screens in the sampler. The disc oxidized nitric-oxide to nitrogen-dioxide which then back diffused and was trapped on the TEA coated screens. Samples were analyzed up to 1 month after exposure by adding a 1.0 milliliter aliquot of azo dye reagent to the sampler, transferring the sample to a cuvette, and reading the transmittance of the resulting colored solution with a specially designed colorimeter. The colorimeter was designed to convert transmittance percent to absorbance and to derive a nanomole nitrogen-dioxide value for each sampler analyzed. The sensitivity range for the colorimeter was 0 to 20 parts per million (ppm). After use, the samplers were recycled by being washed and reloaded with fresh TEA coated screens and chromic-acid discs. Personal samplers and the colorimeter were contained in a complete kit designed for use in the field. Samplers were exposed in the laboratory to incrementally increased nitrogen-dioxide doses from 0 to 55ppm and analyzed 1 day later. Nitrogen-dioxide collection efficiency was linear and had an accuracy of approximately 10 percent for any given concentration. The authors conclude that this personal monitoring system with a designated colorimeter allows efficient collection and accurate monitoring of individual exposures to nitrogen-dioxide or nitric-oxide during a complete 8 hour work shift."
1231314,Anonymous 1980,Approved Occupational Health Guide: Electroplating,"Hazards associated with electroplating and anodizing operations are reviewed. All substances used in electroplating are potentially toxic, but poisoning and gassing are rare. Solutions used in electroplating include chromic-acid (13530682), nickel-sulfate (7786814), nickel-chloride (7718549), cadmium-cyanide (542836), zinc-sulfate (7733020), zinc-cyanide (557211), zinc-chloride (7646857), copper-sulfate (7758987), copper-cyanide (544923), and silver-cyanide (506649). Chromic-acid is strongly irritating to the skin and nasal and bronchial mucosa linings. Nickel (7440020) solutions can cause dermatitis. Cyanide (57125) solutions can form hydrogen-cyanide (74908) if allowed to come into contact with acid. Solvents used in degreasing can cause dermatitis and have toxic effects when vapors are inhaled. Alkalis used in cleaning can irritate the skin, conjunctivae, and respiratory mucosa. Acids used in dipping are corrosive to skin and conjuctivae, and acid mists may affect respiration. Engineering controls should be used to maintain concentrations of atmospheric contaminants given off by plating tanks below the recommended hygienic standards. Chromium (7440473) plating requires mechanical ventilation, although many other plating operations do not. Mists arising from tanks can be reduced by using patented surfactants or plastic chips on the plating solution surface. Tanks, pipe lines, and supply valves should be clearly labeled. Environmental sampling should be performed at regular intervals. Employees should be educated about the hazards involved and trained in the use of personal protective equipment and first aid. Eye washes and showers should be provided in areas where splashes are likely. Specific first aid procedures are given for cyanide poisoning.","Approved Occupational Health Guide: Electroplating Abs: Hazards associated with electroplating and anodizing operations are reviewed. All substances used in electroplating are potentially toxic, but poisoning and gassing are rare. Solutions used in electroplating include chromic-acid (13530682), nickel-sulfate (7786814), nickel-chloride (7718549), cadmium-cyanide (542836), zinc-sulfate (7733020), zinc-cyanide (557211), zinc-chloride (7646857), copper-sulfate (7758987), copper-cyanide (544923), and silver-cyanide (506649). Chromic-acid is strongly irritating to the skin and nasal and bronchial mucosa linings. Nickel (7440020) solutions can cause dermatitis. Cyanide (57125) solutions can form hydrogen-cyanide (74908) if allowed to come into contact with acid. Solvents used in degreasing can cause dermatitis and have toxic effects when vapors are inhaled. Alkalis used in cleaning can irritate the skin, conjunctivae, and respiratory mucosa. Acids used in dipping are corrosive to skin and conjuctivae, and acid mists may affect respiration. Engineering controls should be used to maintain concentrations of atmospheric contaminants given off by plating tanks below the recommended hygienic standards. Chromium (7440473) plating requires mechanical ventilation, although many other plating operations do not. Mists arising from tanks can be reduced by using patented surfactants or plastic chips on the plating solution surface. Tanks, pipe lines, and supply valves should be clearly labeled. Environmental sampling should be performed at regular intervals. Employees should be educated about the hazards involved and trained in the use of personal protective equipment and first aid. Eye washes and showers should be provided in areas where splashes are likely. Specific first aid procedures are given for cyanide poisoning."
1231313,Pryor 1978,"Health Hazard Evaluation Report, No. TA-77-81, Package Machinery Company, East Longmeadow, Massachusetts","Worker exposure to hazardous substances were evaluated on November 17, 1977 at Package Machinery Company (SIC-3551) in East Longmeadow, Massachusetts. The evaluation was requested by a company representative on behalf of about 400 production workers. General and personal air samples were collected in seven different work areas, and analyzed for various solvents, gases, and dusts. Workers completed symptom questionnaires. Workplace ventilation also was assessed. Air concentrations of free silica (14808607) (quartz) and cristobalite (14464461), total particulates, toluene (108883), methyl-ethyl-ketone (78933), iron-oxide (1309371), manganese (7439965), chromic-acid (7738945) and chromates, and carbon-monoxide (630080) were assessed. Concentrations were found to be below respective evaluation standards of 0.05 milligrams per cubic meter (mg/m3), 30mg/m3 divided by the percentage of quartz plus 2, 10mg/m3, 375mg/m3, 590mg/m3, 5.0mg/m3, 5.0mg/m3 (ceiling), 0.5mg/m3, and 35 parts per million. None of the workers reported job related health problems. Ventilation systems were not within design specifications for the polishing/buffing, dipping tank, and chrome plating exhaust systems. The author concludes that no hazardous chemical exposures exist. He recommends ventilation improvements, use of personal protective equipment, retesting at selected work sites, and establishment of a Material Safety Data Sheet file.","Health Hazard Evaluation Report, No. TA-77-81, Package Machinery Company, East Longmeadow, Massachusetts Abs: Worker exposure to hazardous substances were evaluated on November 17, 1977 at Package Machinery Company (SIC-3551) in East Longmeadow, Massachusetts. The evaluation was requested by a company representative on behalf of about 400 production workers. General and personal air samples were collected in seven different work areas, and analyzed for various solvents, gases, and dusts. Workers completed symptom questionnaires. Workplace ventilation also was assessed. Air concentrations of free silica (14808607) (quartz) and cristobalite (14464461), total particulates, toluene (108883), methyl-ethyl-ketone (78933), iron-oxide (1309371), manganese (7439965), chromic-acid (7738945) and chromates, and carbon-monoxide (630080) were assessed. Concentrations were found to be below respective evaluation standards of 0.05 milligrams per cubic meter (mg/m3), 30mg/m3 divided by the percentage of quartz plus 2, 10mg/m3, 375mg/m3, 590mg/m3, 5.0mg/m3, 5.0mg/m3 (ceiling), 0.5mg/m3, and 35 parts per million. None of the workers reported job related health problems. Ventilation systems were not within design specifications for the polishing/buffing, dipping tank, and chrome plating exhaust systems. The author concludes that no hazardous chemical exposures exist. He recommends ventilation improvements, use of personal protective equipment, retesting at selected work sites, and establishment of a Material Safety Data Sheet file."
1231312,Anania et al. 1978,"Health Hazard Evaluation Determination Report No. HHE-77-34-471, Midwest Steel Division, National Steel Corporation, Portage, Indiana","An evaluation of exposure of workers of the Midwest Steel Division of National Steel Corp. to organic solvents, acid mists, caustics, oil mists, asbestos and welding fumes during steel processing has been made. No basic steel is produced at this plant. Raw material in the form of hot rolled coils is received from other plants. The product is directed into one of three channels according to its intended use: 1) tin plate and tin free steel, 2) galvanized (SIC-3312), or 3) cold rolled products (SIC-3316). The survey included over fifteen different areas or processes. Results of the personal and area samples were used to evaluate employee exposures. The personal samples were attached near the breathing zone of the employees to collect a representative sample of air. Atmospheric samples for particulate oil mist and for sulfuric-acid (7664939) were collected. Atmospheric samples for total dust, chromic-acid (7738945), and zinc-oxide (1314132) were collected on 5 microgram polyvinyl-chloride (9002862) (PVC) filters. Atmospheric samples for methyl-chloroform (71556) were collected on activated charcoal tubes. Atmospheric samples for carbon-monoxide (630080) were taken using Drager colorimetric gas detector tube units. Atmospheric samples for hydrogen cyanide (7408) were collected. An atmospheric sample for asbestos (1332214) was collected on an 0.8 microgram mixed cellulose ester filter at a flow rate of 2.01pm. Atmospheric samples for sodium-hydroxide (1310732) were collected with a fritted glass bubbler. An employee exposure to asbestos at the Deep Well exceeded both ceiling values of 0.5 fibers/cc and 10 fibers/cc respectively. All other samples were below the evaluation criteria.","Health Hazard Evaluation Determination Report No. HHE-77-34-471, Midwest Steel Division, National Steel Corporation, Portage, Indiana Abs: An evaluation of exposure of workers of the Midwest Steel Division of National Steel Corp. to organic solvents, acid mists, caustics, oil mists, asbestos and welding fumes during steel processing has been made. No basic steel is produced at this plant. Raw material in the form of hot rolled coils is received from other plants. The product is directed into one of three channels according to its intended use: 1) tin plate and tin free steel, 2) galvanized (SIC-3312), or 3) cold rolled products (SIC-3316). The survey included over fifteen different areas or processes. Results of the personal and area samples were used to evaluate employee exposures. The personal samples were attached near the breathing zone of the employees to collect a representative sample of air. Atmospheric samples for particulate oil mist and for sulfuric-acid (7664939) were collected. Atmospheric samples for total dust, chromic-acid (7738945), and zinc-oxide (1314132) were collected on 5 microgram polyvinyl-chloride (9002862) (PVC) filters. Atmospheric samples for methyl-chloroform (71556) were collected on activated charcoal tubes. Atmospheric samples for carbon-monoxide (630080) were taken using Drager colorimetric gas detector tube units. Atmospheric samples for hydrogen cyanide (7408) were collected. An atmospheric sample for asbestos (1332214) was collected on an 0.8 microgram mixed cellulose ester filter at a flow rate of 2.01pm. Atmospheric samples for sodium-hydroxide (1310732) were collected with a fritted glass bubbler. An employee exposure to asbestos at the Deep Well exceeded both ceiling values of 0.5 fibers/cc and 10 fibers/cc respectively. All other samples were below the evaluation criteria."
1231311,Ruhe and  Andersen 1977,"Health Hazard Evaluation Determination, Report No. HHE-76-17-395, The Hayes and Albion Company, Spencerville, Ohio","A Health Hazard Evaluation investigation was conducted by NIOSH on April 1-2 and July 27-29, 1976, at the Hayes and Albion Company, Spencerville, Ohio, a plant engaged in the manufacturing of automobile trim and side molding (SIC-2396). An authorized employee representative requested the investigation for worker exposure to chemicals in the Anodizing Department, Stripping Room, Paint Room, Vinyl Assembly and Final Assembly area. On the basis of environmental sampling it has been determined that exposure to chromic-acid, sulfuric-acid (7664939), nitric-acid (7697372), methylene-chloride (75092), ethanol (64175), sodium-hydroxide, methyl-ethyl-ketone, toluene (108883), acetone (67641), carbon-monoxide (630080) and vinyl-chloride (75014) did not exceed recommended environmental criteria within the worksite areas. However, based on the answers to medical questionnaires completed by 30 affected workers, it is believed that workers in the spray painting and stripping areas may occasionally be exposed to excessive concentrations of methylene-chloride, methyl-ethyl-ketone (78933) and toluene, which are known to produce nose, throat and skin irritation. Recommendations are made for the use of respirators, establishing hazard educational programs, and servicing of exhaust ventilation systems to insure that they are operating at maximum efficiency.","Health Hazard Evaluation Determination, Report No. HHE-76-17-395, The Hayes and Albion Company, Spencerville, Ohio Abs: A Health Hazard Evaluation investigation was conducted by NIOSH on April 1-2 and July 27-29, 1976, at the Hayes and Albion Company, Spencerville, Ohio, a plant engaged in the manufacturing of automobile trim and side molding (SIC-2396). An authorized employee representative requested the investigation for worker exposure to chemicals in the Anodizing Department, Stripping Room, Paint Room, Vinyl Assembly and Final Assembly area. On the basis of environmental sampling it has been determined that exposure to chromic-acid, sulfuric-acid (7664939), nitric-acid (7697372), methylene-chloride (75092), ethanol (64175), sodium-hydroxide, methyl-ethyl-ketone, toluene (108883), acetone (67641), carbon-monoxide (630080) and vinyl-chloride (75014) did not exceed recommended environmental criteria within the worksite areas. However, based on the answers to medical questionnaires completed by 30 affected workers, it is believed that workers in the spray painting and stripping areas may occasionally be exposed to excessive concentrations of methylene-chloride, methyl-ethyl-ketone (78933) and toluene, which are known to produce nose, throat and skin irritation. Recommendations are made for the use of respirators, establishing hazard educational programs, and servicing of exhaust ventilation systems to insure that they are operating at maximum efficiency."
1231309,Anonymous 1977,Chromium Health And Safety Precautions,"The Health and Safety Executive Guidance Note on chromium is presented. Physical and chemical properties of chromium and chromium compounds are summarized. Hexavalent chromium (18540299) (Cr(VI)), as in chromates and chromic-acid, is the most important industrial form of chromium. Threshold limit values of chromium compounds are reviewed. Industrial uses of metallic chromium and chromium compounds are described. Toxic effects of chromium are discussed. Chromium is most active as a cause of occupational disease when it is in the Cr(VI) form. Poisoning results from inhaling droplets in water or dust, or by skin contact. Acute inhaling exposure to chromic-acid causes upper respiratory tract irritation and occasional asthmatic symptoms. Dermal exposure causes deep, sharply defined ulcers that are slow to heal. Chromates are also irritating to the skin and mucous membranes. These compounds can induce sensitization in exposed workers. Chronic exposure to chromates and dichromates has been associated with an increased incidence of lung cancer. Preventive measures are discussed. These include enclosure of process systems, local exhaust ventilation, good housekeeping practices, and use of personal protective clothing. Medical supervision and first aid measures are summarized.","Chromium Health And Safety Precautions Abs: The Health and Safety Executive Guidance Note on chromium is presented. Physical and chemical properties of chromium and chromium compounds are summarized. Hexavalent chromium (18540299) (Cr(VI)), as in chromates and chromic-acid, is the most important industrial form of chromium. Threshold limit values of chromium compounds are reviewed. Industrial uses of metallic chromium and chromium compounds are described. Toxic effects of chromium are discussed. Chromium is most active as a cause of occupational disease when it is in the Cr(VI) form. Poisoning results from inhaling droplets in water or dust, or by skin contact. Acute inhaling exposure to chromic-acid causes upper respiratory tract irritation and occasional asthmatic symptoms. Dermal exposure causes deep, sharply defined ulcers that are slow to heal. Chromates are also irritating to the skin and mucous membranes. These compounds can induce sensitization in exposed workers. Chronic exposure to chromates and dichromates has been associated with an increased incidence of lung cancer. Preventive measures are discussed. These include enclosure of process systems, local exhaust ventilation, good housekeeping practices, and use of personal protective clothing. Medical supervision and first aid measures are summarized."
1231308,Anonymous 1972,"M-S-A Universal Testing Kits, and Related Individual Kits (Mine Safety Appliances Company)","A description is given of the M-S-A Universal Tester, a portable apparatus for rapid measurement of atmospheric concentrations of a wide variety of toxic gases, mists, dusts and vapors. Kits are produced by the Mine Safety Appliances Co. Three types of detector systems are available: glass tubes containing stable chemicals, tubes to be freshly filled with unstable chemicals, and chemically impregnated filter papers. A measured volume of air is pulled through the detector at a controlled rate using a pump. Colorimetric changes or stain lengths produced in the detector by air contaminants are compared with charts to determine contaminant concentration. For analyzing most halogenated or nitrogenated compounds, a pyrolyzer accessory is available. The manually operated universal sampling pump can collect volumes of 25, 50, 75, or 100cc at rates controlled by rotating an indexed head placed over a protective filter and four orifices. Model 1 of the tester contains the pump, spare parts, operating instructions, and ordering instructions in a moisture and dust proof container measuring 13""x10""x2.5"" and with room for 12 packages of detector tubes. Model 2 contains Model 1 materials along with more space for carrying accessories. A Remote Sampling Kit includes an adaptor for fitting a 10, 25, or 50 sampling line (to be ordered separately) to the universal pump. Filter Paper and Reagent Kit accessories for the detection of arsine (7784421), boranes, chromic-acid (7738945) mists, hydrogen-fluoride (7664393), and unsymmetrical dimethyl-hydrazine (57147) in air are available.","M-S-A Universal Testing Kits, and Related Individual Kits (Mine Safety Appliances Company) Abs: A description is given of the M-S-A Universal Tester, a portable apparatus for rapid measurement of atmospheric concentrations of a wide variety of toxic gases, mists, dusts and vapors. Kits are produced by the Mine Safety Appliances Co. Three types of detector systems are available: glass tubes containing stable chemicals, tubes to be freshly filled with unstable chemicals, and chemically impregnated filter papers. A measured volume of air is pulled through the detector at a controlled rate using a pump. Colorimetric changes or stain lengths produced in the detector by air contaminants are compared with charts to determine contaminant concentration. For analyzing most halogenated or nitrogenated compounds, a pyrolyzer accessory is available. The manually operated universal sampling pump can collect volumes of 25, 50, 75, or 100cc at rates controlled by rotating an indexed head placed over a protective filter and four orifices. Model 1 of the tester contains the pump, spare parts, operating instructions, and ordering instructions in a moisture and dust proof container measuring 13""x10""x2.5"" and with room for 12 packages of detector tubes. Model 2 contains Model 1 materials along with more space for carrying accessories. A Remote Sampling Kit includes an adaptor for fitting a 10, 25, or 50 sampling line (to be ordered separately) to the universal pump. Filter Paper and Reagent Kit accessories for the detection of arsine (7784421), boranes, chromic-acid (7738945) mists, hydrogen-fluoride (7664393), and unsymmetrical dimethyl-hydrazine (57147) in air are available."
1231307,Anonymous 1973,Zinc Dermatitis and Discolorations,"Zinc-chloride (7646857) is a strong primary irritant, producing ulcerations resembling those produced by chromic-acid (7738945). Exposure can arise from dental fillings, preservation and fireproofing of timber, solder flux, and Hon's chemosurgery for skin cancer. Zinc-oxide is probably the most common cause of black dermographism produced by jewelry. Zinc-oxide is present in cosmetics, lotions, and dentifrices. Zinc-stearate (557051) is so soft that it cannot cause black dermographism. D'Alibour solution, containing zinc-sulfate (7733020), copper-sulfate (7758987) and camphorated water, is sometimes used as a wet dressing, but it has not been reported as a cause of allergic dermatitis. Zinc-pyrethione (13463417) is present in a 1 percent concentration in Head and Shoulders Shampoo. There is no specific reference made to chromium (7440473) in this paper.","Zinc Dermatitis and Discolorations Abs: Zinc-chloride (7646857) is a strong primary irritant, producing ulcerations resembling those produced by chromic-acid (7738945). Exposure can arise from dental fillings, preservation and fireproofing of timber, solder flux, and Hon's chemosurgery for skin cancer. Zinc-oxide is probably the most common cause of black dermographism produced by jewelry. Zinc-oxide is present in cosmetics, lotions, and dentifrices. Zinc-stearate (557051) is so soft that it cannot cause black dermographism. D'Alibour solution, containing zinc-sulfate (7733020), copper-sulfate (7758987) and camphorated water, is sometimes used as a wet dressing, but it has not been reported as a cause of allergic dermatitis. Zinc-pyrethione (13463417) is present in a 1 percent concentration in Head and Shoulders Shampoo. There is no specific reference made to chromium (7440473) in this paper."
1231306,Geissert 1976,"Health Hazard Evaluation Determination, Report No. HHE-75-158-299, Federal Products Corporation, Providence, Rhode Island","A Health Hazard Evaluation investigation was conducted by NIOSH on October 22-24, 1975, and January 27-29, 1976, at Federal Products, Providence, Rhode Island, a facility engaged in the manufacture of precision linear instruments (SIC-3545) and their accessories. The survey was prompted by a request from the employer regarding employee exposure to a variety of dusts, fumes and vapors. Measurements of workplace concentrations of airborne chemicals, evaluation of process operations and control measures, medical interviews, and a review of the pertinent literature led to the conclusion that exposures of employees to ammonia (7664417), beryllium (7440417), chromic-acid (7738945), lead (7439921), methyl-ethyl-ketone (78933), fumes, nitric-acid (7697372), nuisance dusts, oil mist, sodium-hydroxide (1310732), toluene-diisocyanate (1321386), 1,1,1-trichloroethane (71556), 1,1,2-trichloro-1,2,2-trifluoroethane (354585), welding fumes, mahogany wood dust and wood dust, and operations in the print shop, dark room and lapping were not toxic to employees. Employee exposure to free silica (7631869) at the vacu-blast operation was potentially toxic. Recommendations are made to reduce the dermatitis experienced by employees in some departments.","Health Hazard Evaluation Determination, Report No. HHE-75-158-299, Federal Products Corporation, Providence, Rhode Island Abs: A Health Hazard Evaluation investigation was conducted by NIOSH on October 22-24, 1975, and January 27-29, 1976, at Federal Products, Providence, Rhode Island, a facility engaged in the manufacture of precision linear instruments (SIC-3545) and their accessories. The survey was prompted by a request from the employer regarding employee exposure to a variety of dusts, fumes and vapors. Measurements of workplace concentrations of airborne chemicals, evaluation of process operations and control measures, medical interviews, and a review of the pertinent literature led to the conclusion that exposures of employees to ammonia (7664417), beryllium (7440417), chromic-acid (7738945), lead (7439921), methyl-ethyl-ketone (78933), fumes, nitric-acid (7697372), nuisance dusts, oil mist, sodium-hydroxide (1310732), toluene-diisocyanate (1321386), 1,1,1-trichloroethane (71556), 1,1,2-trichloro-1,2,2-trifluoroethane (354585), welding fumes, mahogany wood dust and wood dust, and operations in the print shop, dark room and lapping were not toxic to employees. Employee exposure to free silica (7631869) at the vacu-blast operation was potentially toxic. Recommendations are made to reduce the dermatitis experienced by employees in some departments."
1231304,Zumwalde 1974,"Preliminary Industrial Hygiene Survey of City Bumper Incorporated, Cincinnati, Ohio","A survey of a chrome plating facility (SIC-3471) was carried out for the purposes of familiarization with chrome plating operations, and obtaining preliminary environmental air measurements so that work environments with chromic-acid (7738945) exposure levels less than 0.05 and 0.10 milligram per cubic meter could be identified for more detailed industrial hygiene surveys. A total of 10 air samples, both personal and general area were taken for evaluation of chromic-acid. Wipe samples were collected from surfaces in the work environment and tested for hexavalent chromium (7440473). Ventilation measurements also were made in some areas.","Preliminary Industrial Hygiene Survey of City Bumper Incorporated, Cincinnati, Ohio Abs: A survey of a chrome plating facility (SIC-3471) was carried out for the purposes of familiarization with chrome plating operations, and obtaining preliminary environmental air measurements so that work environments with chromic-acid (7738945) exposure levels less than 0.05 and 0.10 milligram per cubic meter could be identified for more detailed industrial hygiene surveys. A total of 10 air samples, both personal and general area were taken for evaluation of chromic-acid. Wipe samples were collected from surfaces in the work environment and tested for hexavalent chromium (7440473). Ventilation measurements also were made in some areas."
1231303,Anonymous 1972,Chromic Acid Mist in Air,An atomic absorption method is described for the determination of chromic-acid (7738945) in air using nitrous-oxide (10024972) acetylene (74862) burner head. Atmospheric samples are obtained by drawing a measured volume of air through a 0.8 micron filter. The filter is wet ashed and analyzed for chromium (7440473) by atomic absorption spectroscopy using a nitrous-oxide-acetylene flame.,Chromic Acid Mist in Air Abs: An atomic absorption method is described for the determination of chromic-acid (7738945) in air using nitrous-oxide (10024972) acetylene (74862) burner head. Atmospheric samples are obtained by drawing a measured volume of air through a 0.8 micron filter. The filter is wet ashed and analyzed for chromium (7440473) by atomic absorption spectroscopy using a nitrous-oxide-acetylene flame.
1231302,Anonymous 1973,Acceptable Concentrations of Chromic Acid and Hexavalent Chromium Compounds,"The American National Standards Institute's acceptable concentrations for chromic-acid (7738945) and chromium (7440473) are presented for guidance in establishing engineering procedures to prevent objectionable concentrations of materials in the air of workplaces. The acceptable limit is 0.3 milligram chromium trioxide per cubic meter for chromic-acid and soluble chromates, based on an 8 hour work day, provided the time-weighted average concentration is at or below 0.1 milligram per cubic meter. If the work week is greater than 40 hours, the acceptable concentration shall be reduced proportionately. The value is based primarily on human experience with chromic-acid and soluble chromates. Extension to insoluble chromates is based largely on animal experiments in which different chromium compounds are compared. Effects of chromate dust and mist include cancer of the lung, nose bleeds, and perforation or ulceration of the nasal septum.","Acceptable Concentrations of Chromic Acid and Hexavalent Chromium Compounds Abs: The American National Standards Institute's acceptable concentrations for chromic-acid (7738945) and chromium (7440473) are presented for guidance in establishing engineering procedures to prevent objectionable concentrations of materials in the air of workplaces. The acceptable limit is 0.3 milligram chromium trioxide per cubic meter for chromic-acid and soluble chromates, based on an 8 hour work day, provided the time-weighted average concentration is at or below 0.1 milligram per cubic meter. If the work week is greater than 40 hours, the acceptable concentration shall be reduced proportionately. The value is based primarily on human experience with chromic-acid and soluble chromates. Extension to insoluble chromates is based largely on animal experiments in which different chromium compounds are compared. Effects of chromate dust and mist include cancer of the lung, nose bleeds, and perforation or ulceration of the nasal septum."
1231301,Zumwalde 1974,"Preliminary Industrial Hygiene Survey of Leonhardt Company, Cincinnati, Ohio","A survey was conducted of a plant involved in decorative chrome plating (SIC-3471), and preliminary environmental air measurements for chromic-acid were obtained. A total of ten air samples, both personal and general area were taken for evaluation of chromic-acid, and wipe samples were collected from various surfaces in the work environment and tested for hexavalent chromium (7440473).","Preliminary Industrial Hygiene Survey of Leonhardt Company, Cincinnati, Ohio Abs: A survey was conducted of a plant involved in decorative chrome plating (SIC-3471), and preliminary environmental air measurements for chromic-acid were obtained. A total of ten air samples, both personal and general area were taken for evaluation of chromic-acid, and wipe samples were collected from various surfaces in the work environment and tested for hexavalent chromium (7440473)."
1231300,Lucas and  Kramkowski 1975,"Health Hazard Evaluation Report No. HHE-74-87-221, Industrial Platers, Inc., Columbus, Ohio","An environmental medical study performed of the electroplating processes of the Industrial Platers, Inc. (SIC-3356), Columbus, Ohio, revealed that chromic-acid (13907454) exposure is a hazard for the employees within the hard chrome area. Four men had perforated nasal septa and 2 others to have some degree of septal ulceration. Cutaneous scars resulting from past chrome ulceration were noted in 9 of the 11 employees examined. While the majority of the signs and symptoms of chromate exposure elicited during this study dated back at least several years, there was evidence that adverse effects are continuing to occur within this plant. As evidence of this, are the five individuals in whom injected nasal mucosa were noted and the 2 men with active septal ulceration. While several workmen who are long-term employees described numerous beneficial changes in ventilation, it is apparent that some adverse effects from chromic-acid are still occurring. Workroom airborne concentrations of chromic-acid as measured during this evaluation were well below any existing or recommended standards. The observations of work practices, including the use of personal protective equipment, the presence of characteristic orange chromate stains on workers' skin and the results of spot tests in the work area suggest that much of the nasal and cutaneous pathology that have occurred and continue to occur within this plant probably result from direct contact with the hexavalent chromate ion rather than through airborne exposure.","Health Hazard Evaluation Report No. HHE-74-87-221, Industrial Platers, Inc., Columbus, Ohio Abs: An environmental medical study performed of the electroplating processes of the Industrial Platers, Inc. (SIC-3356), Columbus, Ohio, revealed that chromic-acid (13907454) exposure is a hazard for the employees within the hard chrome area. Four men had perforated nasal septa and 2 others to have some degree of septal ulceration. Cutaneous scars resulting from past chrome ulceration were noted in 9 of the 11 employees examined. While the majority of the signs and symptoms of chromate exposure elicited during this study dated back at least several years, there was evidence that adverse effects are continuing to occur within this plant. As evidence of this, are the five individuals in whom injected nasal mucosa were noted and the 2 men with active septal ulceration. While several workmen who are long-term employees described numerous beneficial changes in ventilation, it is apparent that some adverse effects from chromic-acid are still occurring. Workroom airborne concentrations of chromic-acid as measured during this evaluation were well below any existing or recommended standards. The observations of work practices, including the use of personal protective equipment, the presence of characteristic orange chromate stains on workers' skin and the results of spot tests in the work area suggest that much of the nasal and cutaneous pathology that have occurred and continue to occur within this plant probably result from direct contact with the hexavalent chromate ion rather than through airborne exposure."
1231299,Anonymous 1976,Occupation and Disease A Guide for Decision-Making,"This guide presents a general method for assembling and evaluating medical and environmental data to assist in deciding whether a disease condition is of occupational origin. Data are given for 15 specific disease producing agents: antimony (7440360), arsenic (7440382), asbestos (1332214), benzene (71432), beryllium (7440417), carbon-monoxide (630080), chromic-acid (1333820), coke oven emissions, cotton dust, lead (7439921) (inorganic), nitrogen-dioxide (10102440), noise, silica (7631869), sulfur-dioxide (7446095), and toluene-diisocyanate (584849). Detailed considerations are included covering medical, personal, family and occupational histories, clinical evaluation, signs and symptoms of occupational diseases, laboratory tests, epidemiological data, industrial hygiene sampling and evaluation data, and established standards for exposure to occupational disease producing agents. Also included are a discussion of aggravation of preexisting conditions and legal ramifications thereof; guidelines for assessing the qualifications of medical and industrial hygiene personnel who may present testimony; normal values for various biological tests and variables; sample questionnaires for evaluating respiratory symptoms; a listing of occupations with possible exposure to the 15 agents; and references giving toxicological data for these agents. (Contract No. 210-75-0075)","Occupation and Disease A Guide for Decision-Making Abs: This guide presents a general method for assembling and evaluating medical and environmental data to assist in deciding whether a disease condition is of occupational origin. Data are given for 15 specific disease producing agents: antimony (7440360), arsenic (7440382), asbestos (1332214), benzene (71432), beryllium (7440417), carbon-monoxide (630080), chromic-acid (1333820), coke oven emissions, cotton dust, lead (7439921) (inorganic), nitrogen-dioxide (10102440), noise, silica (7631869), sulfur-dioxide (7446095), and toluene-diisocyanate (584849). Detailed considerations are included covering medical, personal, family and occupational histories, clinical evaluation, signs and symptoms of occupational diseases, laboratory tests, epidemiological data, industrial hygiene sampling and evaluation data, and established standards for exposure to occupational disease producing agents. Also included are a discussion of aggravation of preexisting conditions and legal ramifications thereof; guidelines for assessing the qualifications of medical and industrial hygiene personnel who may present testimony; normal values for various biological tests and variables; sample questionnaires for evaluating respiratory symptoms; a listing of occupations with possible exposure to the 15 agents; and references giving toxicological data for these agents. (Contract No. 210-75-0075)"
1231298,Anonymous 1974,NIOSH Manual of Analytical Methods,"Analytical methods were presented for determining about 135 chemicals in the atmosphere, in the workplace, and in biological materials. Specifically, methods were given for determining lead (7439921), mercury (7439976), antimony (7440360), arsenic (7440382), and fluoride (16984488) in urine; lead and mercury in blood; nitrogen-dioxide (10102440), carbon-monoxide (630080), cyanide (57125), acrolein (107028), beryllium (7440417), formaldehyde (50000), organic solvents, hydrogen-sulfide (7783064), arsenic, 2,4-toluenediisocyanate (584849), sulfur-dioxide (7446095), p,p'-diphenylmethanediisocyanate (101688), vinyl-chloride (75014), cadmium (7440439), chromium (7440473), ozone (10028156), lead, parathion (56382), oil mists, aromatic amines, chromic-acid (1333820) mist, fluoride, hydrogen-fluoride (7664393), and mercury in air; free silica (7631869) in atmospheric dust; and quartz (14808607) in coal dust. For each analytical procedure described the principle of the method was presented followed by the range and sensitivity, possible interferences, precision and accuracy, advantages and disadvantages of the method, apparatus used, reagents, procedure, collection and shipping of samples, analysis of samples, calibration and standards, calculations, and citations to additional references of interest.","NIOSH Manual of Analytical Methods Abs: Analytical methods were presented for determining about 135 chemicals in the atmosphere, in the workplace, and in biological materials. Specifically, methods were given for determining lead (7439921), mercury (7439976), antimony (7440360), arsenic (7440382), and fluoride (16984488) in urine; lead and mercury in blood; nitrogen-dioxide (10102440), carbon-monoxide (630080), cyanide (57125), acrolein (107028), beryllium (7440417), formaldehyde (50000), organic solvents, hydrogen-sulfide (7783064), arsenic, 2,4-toluenediisocyanate (584849), sulfur-dioxide (7446095), p,p'-diphenylmethanediisocyanate (101688), vinyl-chloride (75014), cadmium (7440439), chromium (7440473), ozone (10028156), lead, parathion (56382), oil mists, aromatic amines, chromic-acid (1333820) mist, fluoride, hydrogen-fluoride (7664393), and mercury in air; free silica (7631869) in atmospheric dust; and quartz (14808607) in coal dust. For each analytical procedure described the principle of the method was presented followed by the range and sensitivity, possible interferences, precision and accuracy, advantages and disadvantages of the method, apparatus used, reagents, procedure, collection and shipping of samples, analysis of samples, calibration and standards, calculations, and citations to additional references of interest."
1231297,Samitz 1974,Prevention of Occupational Skin Diseases from Exposure to Chromic Acid and Chromates: Use of Ascorbic Acid,"A review of preventive measures for the control of the irritant and sensitizing action caused by chromates reveals that ascorbic acid is effective in preventing and treating a variety of such adverse reactions. A 10 percent ascorbic-acid (50817) solution shortens the time required for the healing of skin ulcers produced by potassium-chromate (7789006) in guinea-pigs, while the impregnation of ascorbic-acid into the filters of respirators enhances protection against inhalation of chromic-acid (7738945) mist. A preventive regimen with 10 percent aqueous ascorbic-acid proved effective in the printing industry and in the lithographing industry.","Prevention of Occupational Skin Diseases from Exposure to Chromic Acid and Chromates: Use of Ascorbic Acid Abs: A review of preventive measures for the control of the irritant and sensitizing action caused by chromates reveals that ascorbic acid is effective in preventing and treating a variety of such adverse reactions. A 10 percent ascorbic-acid (50817) solution shortens the time required for the healing of skin ulcers produced by potassium-chromate (7789006) in guinea-pigs, while the impregnation of ascorbic-acid into the filters of respirators enhances protection against inhalation of chromic-acid (7738945) mist. A preventive regimen with 10 percent aqueous ascorbic-acid proved effective in the printing industry and in the lithographing industry."
1231296,Rosensteel and  Lucas 1974,"Health Hazard Evaluation Determination Report No. HHE-73-40-116, Delco Morain Division, GMC Corporation, Dayton, Ohio","Analysis of samples of airborne particulates and medical evaluation at an industrial facility reveals that antimony (7440360), asbestos (1332214), chromic acid (7738945), copper (7440508), cyanide, iron (7439896), lead (7439921), nickel (7440020), cutting oils, sodium hydroxide (1310732), tin (7440315), and zinc stearate (557051) are not expected to cause toxic effects in exposed workers. The reported number of cases of dermatitis, upper respiratory irritation and eye irritation are apparently episodic and not judged to be excessive in the plant studied.","Health Hazard Evaluation Determination Report No. HHE-73-40-116, Delco Morain Division, GMC Corporation, Dayton, Ohio Abs: Analysis of samples of airborne particulates and medical evaluation at an industrial facility reveals that antimony (7440360), asbestos (1332214), chromic acid (7738945), copper (7440508), cyanide, iron (7439896), lead (7439921), nickel (7440020), cutting oils, sodium hydroxide (1310732), tin (7440315), and zinc stearate (557051) are not expected to cause toxic effects in exposed workers. The reported number of cases of dermatitis, upper respiratory irritation and eye irritation are apparently episodic and not judged to be excessive in the plant studied."
1231293,Ayer 1975,Epidemiologic Studies of Occupational Diseases,"A wide range of epidemiological studies was reported, each of which dealt with a sample of a working population and examined the effects on these workers of the chemicals and other hazardous materials to which they were exposed. Specific materials or exposures noted in these studies included acrylamide (79061), acrylonitrile (107131), aldrin (309002), arsenic (7440382), asbestos (1332214), benzene (71432), benzidine (92875), beryllium (7440417), budgerigars, carbon-disulfide (75150), carbon-monoxide (630080), chromium-oxide (1308389), Portland cement, chlorinated naphthalenes, chloromethyl-methyl-ether (107302), bischloromethyl-ether (542881), chromic-acid (1333820), coal, coke manufacture, cotton (along with flax, hemp, jute, and sisal), DDT (50293), dichlorvos (62737), diphenyl (92524), ferrosilicon, fibrous glass, fluorides, grain, granite, graphite (7782425), gum acacia, hair spray lacquer, iron-oxide (1309371), lead (7439921), lindane (58899), manganese (7439965), mercury (7439976), methyl-n-butylketone (591786), methylene-chloride (75092), nitrogen-oxides, oil mists, parathion (56382), paraquat (1910425), pesticides, polyvinyl-chloride (9002862), potash, proteolytic enzymes, silica (7631869), styrene (100425), solvents, sulfuric-acid (7664939), talc (14807966), trichloroethylene (79016), trichlorotrifluoroethane (76131), 2,4,5-trichlorophenoxyacetic-acid (93765), wood, and xylene (1330207).","Epidemiologic Studies of Occupational Diseases Abs: A wide range of epidemiological studies was reported, each of which dealt with a sample of a working population and examined the effects on these workers of the chemicals and other hazardous materials to which they were exposed. Specific materials or exposures noted in these studies included acrylamide (79061), acrylonitrile (107131), aldrin (309002), arsenic (7440382), asbestos (1332214), benzene (71432), benzidine (92875), beryllium (7440417), budgerigars, carbon-disulfide (75150), carbon-monoxide (630080), chromium-oxide (1308389), Portland cement, chlorinated naphthalenes, chloromethyl-methyl-ether (107302), bischloromethyl-ether (542881), chromic-acid (1333820), coal, coke manufacture, cotton (along with flax, hemp, jute, and sisal), DDT (50293), dichlorvos (62737), diphenyl (92524), ferrosilicon, fibrous glass, fluorides, grain, granite, graphite (7782425), gum acacia, hair spray lacquer, iron-oxide (1309371), lead (7439921), lindane (58899), manganese (7439965), mercury (7439976), methyl-n-butylketone (591786), methylene-chloride (75092), nitrogen-oxides, oil mists, parathion (56382), paraquat (1910425), pesticides, polyvinyl-chloride (9002862), potash, proteolytic enzymes, silica (7631869), styrene (100425), solvents, sulfuric-acid (7664939), talc (14807966), trichloroethylene (79016), trichlorotrifluoroethane (76131), 2,4,5-trichlorophenoxyacetic-acid (93765), wood, and xylene (1330207)."
1231292,Anonymous 1976,Current Intelligence Bulletin 4 Chrome Pigment,"Updated information on health hazards associated with lead-chromate (7758976) (chrome pigment) was discussed. Results of an epidemiologic study and an industrial hygiene survey of three lead-chromate facilities sponsored by the Dry Color Manufacturer's Association (DCMA) were summarized. The epidemiologic study, with a cohort of 548 men, showed that workers exposed to lead-chromate at two facilities had a three fold excess of respiratory cancer. Employees at the third facility, who had zinc-chromate (13530659) exposure as well as lead-chromate exposure, also had a significant excess of mortality due to respiratory cancer. Additionally, a seven fold excess in stomach cancer mortality was observed in employees at the third facility. The industrial hygiene survey showed that nearly half of the samples at the three facilities reached or exceeded the OSHA standards for lead (7439921) and chromium (7440473). The current standards at the time of this report were as follows: lead, 0.2mg/m3; chromium as soluble chromium or chromium salts, 0.5mg/m3, and chromium as chromic-acid (7738945) or chromates, 0.1mg/m3. It is concluded that the results of the DCMA epidemiologic and industrial hygiene studies indicate that lead-chromate should be regarded as a human carcinogen.","Current Intelligence Bulletin 4 Chrome Pigment Abs: Updated information on health hazards associated with lead-chromate (7758976) (chrome pigment) was discussed. Results of an epidemiologic study and an industrial hygiene survey of three lead-chromate facilities sponsored by the Dry Color Manufacturer's Association (DCMA) were summarized. The epidemiologic study, with a cohort of 548 men, showed that workers exposed to lead-chromate at two facilities had a three fold excess of respiratory cancer. Employees at the third facility, who had zinc-chromate (13530659) exposure as well as lead-chromate exposure, also had a significant excess of mortality due to respiratory cancer. Additionally, a seven fold excess in stomach cancer mortality was observed in employees at the third facility. The industrial hygiene survey showed that nearly half of the samples at the three facilities reached or exceeded the OSHA standards for lead (7439921) and chromium (7440473). The current standards at the time of this report were as follows: lead, 0.2mg/m3; chromium as soluble chromium or chromium salts, 0.5mg/m3, and chromium as chromic-acid (7738945) or chromates, 0.1mg/m3. It is concluded that the results of the DCMA epidemiologic and industrial hygiene studies indicate that lead-chromate should be regarded as a human carcinogen."
1231290,Anonymous 1976,NIOSH Analytical Methods for Set O,"Industrial hygiene sampling and analytical monitoring methods are described for chromic-acid (7738945) and chromates; chromium (7440473) in soluble chromic and chromous salts; magnesium-oxide (1309484) fume; chromium in metal and insoluble compounds; lead (7439921) and inorganic lead compounds; molybdenum (7439987) in insoluble compounds; and titanium dioxide (13463677). The methods are validated under the joint NIOSH Standards Completion Program for Set-O. For each compound, the analyte, matrix, OSHA standard and validation date are given, and the method is described in terms of the principle of the method, range and sensitivity, interferences, precision and accuracy, advantages and disadvantages, apparatus, reagents, detailed procedure, analysis, sample recovery, calibration and standards, calculations, and references. Compounds are collected by filter collection and analyses are by atomic absorption or colorimetry. The methods are verified as suitable for measuring airborne concentrations of the listed compounds, but other methods meeting the accuracy requirements may be used.","NIOSH Analytical Methods for Set O Abs: Industrial hygiene sampling and analytical monitoring methods are described for chromic-acid (7738945) and chromates; chromium (7440473) in soluble chromic and chromous salts; magnesium-oxide (1309484) fume; chromium in metal and insoluble compounds; lead (7439921) and inorganic lead compounds; molybdenum (7439987) in insoluble compounds; and titanium dioxide (13463677). The methods are validated under the joint NIOSH Standards Completion Program for Set-O. For each compound, the analyte, matrix, OSHA standard and validation date are given, and the method is described in terms of the principle of the method, range and sensitivity, interferences, precision and accuracy, advantages and disadvantages, apparatus, reagents, detailed procedure, analysis, sample recovery, calibration and standards, calculations, and references. Compounds are collected by filter collection and analyses are by atomic absorption or colorimetry. The methods are verified as suitable for measuring airborne concentrations of the listed compounds, but other methods meeting the accuracy requirements may be used."
1231289,Jelenko 1974,"Chemicals that ""burn""","Chemical insult to the skin or the enteric tract is reviewed. The manner in which chemical agents destroy tissue is described. It is noted that as a class these chemicals coagulate protein by reduction, oxidation, salt formation, corrosion, protoplasmic poisoning, metabolic competition and inhibition, desiccation, or the ischemic components of vesicant activity. The actions, toxic potential, and basic emergency therapy for various chemical agents that harm the skin or the enteric tract are summarized. Oxidizing agents such as chromic-acid (7738945), sodium-hypochlorite (7681529), and potassium-permanganate (7722647) are discussed. Reducing agents including alkyl mercuric agents, hydrochloric-acid (7647010), and nitric-acid (7697372) are considered. Corrosive agents including the phenols and cresols, white-phosphorous, dichromate salts, sodium metals, and the lyes are addressed. Among the protoplasmic poisons, the alkaloidal acids, acetic-acid (64175), formic-acid (64186), and the metabolic competitors and inhibitors are examined. Sulfuric-acid (7664939) and muriatic-acid (7647010) are described in the section on the desiccants. Cantharides, dimethyl-sulfoxide (67685), mustard-gas (505602), and lewisite (1306021) are considered in the discussion of the vesicants.","Chemicals that ""burn"" Abs: Chemical insult to the skin or the enteric tract is reviewed. The manner in which chemical agents destroy tissue is described. It is noted that as a class these chemicals coagulate protein by reduction, oxidation, salt formation, corrosion, protoplasmic poisoning, metabolic competition and inhibition, desiccation, or the ischemic components of vesicant activity. The actions, toxic potential, and basic emergency therapy for various chemical agents that harm the skin or the enteric tract are summarized. Oxidizing agents such as chromic-acid (7738945), sodium-hypochlorite (7681529), and potassium-permanganate (7722647) are discussed. Reducing agents including alkyl mercuric agents, hydrochloric-acid (7647010), and nitric-acid (7697372) are considered. Corrosive agents including the phenols and cresols, white-phosphorous, dichromate salts, sodium metals, and the lyes are addressed. Among the protoplasmic poisons, the alkaloidal acids, acetic-acid (64175), formic-acid (64186), and the metabolic competitors and inhibitors are examined. Sulfuric-acid (7664939) and muriatic-acid (7647010) are described in the section on the desiccants. Cantharides, dimethyl-sulfoxide (67685), mustard-gas (505602), and lewisite (1306021) are considered in the discussion of the vesicants."
1231288,Uytdenhoef 1939,A Few Reflections on Occupational Dermatoses,"Information on occupational dermatoses is reviewed based on results of investigations by the Belgian Center for Occupational Health. The nature, frequency, and social impact of the skin disorders resulting from occupational exposure are discussed. Chemicals commonly associated with occupational skin disorders are reviewed, along with findings of epidemiological investigations of workers exposed to caustics in the chemical, tannery, electrolytic plating, and photoengraving industries. The author concludes that the most common skin disorders are caused by by-products of coal and chromium (7440473). Skin disorders arise from involvement in production of compressed fuel, tar distillation, and production and handling of chromic-acid (7738945) and alkaline-bichromates. (French).","A Few Reflections on Occupational Dermatoses Abs: Information on occupational dermatoses is reviewed based on results of investigations by the Belgian Center for Occupational Health. The nature, frequency, and social impact of the skin disorders resulting from occupational exposure are discussed. Chemicals commonly associated with occupational skin disorders are reviewed, along with findings of epidemiological investigations of workers exposed to caustics in the chemical, tannery, electrolytic plating, and photoengraving industries. The author concludes that the most common skin disorders are caused by by-products of coal and chromium (7440473). Skin disorders arise from involvement in production of compressed fuel, tar distillation, and production and handling of chromic-acid (7738945) and alkaline-bichromates. (French)."
1231287,Anonymous 1966,Chromium compounds,"Chromium compounds include chromic-acid (7738945), chromates, and bichromates. Inhalation of dust or mist of chromates or chromic-acid can produce small, painless cutaneous ulcers as well as dermatitis from primary irritation or allergic hypersensitivity. Cutaneous allergy is not uncommon from hexavalent chromium compounds, but is extremely rare from trivalent chromium compounds. Systemic effects of exposure include allergic bronchial asthma from chromium trioxide fume. Bronchogenic carcinoma has occurred at an abnormally high rate among chromate workers. Special diagnostic tests include the determination of chromium (7440473) in blood and urine. The recommended threshold limit for chromic-acid and chromates is 0.1 milligrams per cubic meter of air. Potential occupational exposures include: abrasive makers, acetylene purifiers, adhesive workers, airplane sprayers, alloy makers, aluminum anodizers, battery industry, ceramic processing, cement industry, chrome alloy manufacturing, furniture industry, glass workers, leather industry, metalworking industry, and organic chemical synthesis.","Chromium compounds Abs: Chromium compounds include chromic-acid (7738945), chromates, and bichromates. Inhalation of dust or mist of chromates or chromic-acid can produce small, painless cutaneous ulcers as well as dermatitis from primary irritation or allergic hypersensitivity. Cutaneous allergy is not uncommon from hexavalent chromium compounds, but is extremely rare from trivalent chromium compounds. Systemic effects of exposure include allergic bronchial asthma from chromium trioxide fume. Bronchogenic carcinoma has occurred at an abnormally high rate among chromate workers. Special diagnostic tests include the determination of chromium (7440473) in blood and urine. The recommended threshold limit for chromic-acid and chromates is 0.1 milligrams per cubic meter of air. Potential occupational exposures include: abrasive makers, acetylene purifiers, adhesive workers, airplane sprayers, alloy makers, aluminum anodizers, battery industry, ceramic processing, cement industry, chrome alloy manufacturing, furniture industry, glass workers, leather industry, metalworking industry, and organic chemical synthesis."
1231286,Sterner 1943,"Determining Margins of Safety Criteria for Defining a ""Harmful"" Exposure","The practical problem of defining what is harmful in the occupational environment is discussed. When environmental conditions improve, a marginal zone is reached in which the injuries sustained are slight and quickly reversible or amount only to a tolerable discomfort. Another aspect of the problem is that of the relation of the industrial exposure to the possible increase in diseases not recognized as occupational in origin. The medical and hygiene examination of the workers and working environment is an essential factor in the evaluation of an exposure. An example of the ""normal"" values of hemoglobin and other blood constituents is given for a sample of workmen. Also given are the maximum permissible concentrations of gases and vapors such as acids, ketones, amines, hydrocarbons, alcohols, ethers, aldehydes, and chlorinated compounds; for fumes of metallic oxides and napthalenes; dusts such as asbestos (1332214), and silica (7631869); and for chromic-acid (7738945) and sulfuric-acid (7664939) mists. The maximum allowable concentration for sulfuric-acid is given as 5 milligrams per cubic meter of air.","Determining Margins of Safety Criteria for Defining a ""Harmful"" Exposure Abs: The practical problem of defining what is harmful in the occupational environment is discussed. When environmental conditions improve, a marginal zone is reached in which the injuries sustained are slight and quickly reversible or amount only to a tolerable discomfort. Another aspect of the problem is that of the relation of the industrial exposure to the possible increase in diseases not recognized as occupational in origin. The medical and hygiene examination of the workers and working environment is an essential factor in the evaluation of an exposure. An example of the ""normal"" values of hemoglobin and other blood constituents is given for a sample of workmen. Also given are the maximum permissible concentrations of gases and vapors such as acids, ketones, amines, hydrocarbons, alcohols, ethers, aldehydes, and chlorinated compounds; for fumes of metallic oxides and napthalenes; dusts such as asbestos (1332214), and silica (7631869); and for chromic-acid (7738945) and sulfuric-acid (7664939) mists. The maximum allowable concentration for sulfuric-acid is given as 5 milligrams per cubic meter of air."
1231285,Major 1922,Study on a Case of Chromic Acid Nephritis,"A case of chromic-acid poisoning is studied, with emphasis on kidney pathology and comparison with experimental chromate nephritis. The patient, suffering from an inoperable carcinoma of the face which had been treated by the application of chromic-acid (7738945) crystals, lived for 4 weeks after the development of the nephritis. Extensive studies of the blood and urine were carried out, marked variations from the normal were encountered and changes brought about by therapeutic measures were noted.","Study on a Case of Chromic Acid Nephritis Abs: A case of chromic-acid poisoning is studied, with emphasis on kidney pathology and comparison with experimental chromate nephritis. The patient, suffering from an inoperable carcinoma of the face which had been treated by the application of chromic-acid (7738945) crystals, lived for 4 weeks after the development of the nephritis. Extensive studies of the blood and urine were carried out, marked variations from the normal were encountered and changes brought about by therapeutic measures were noted."
1231281,Dankman 1952,Industrial Exposure to Chromates in New York State,"The most common industrial uses of chromates in New York State and the types of exposures associated with them, are reviewed briefly. The most toxic chromium (7440473) derivatives are the hexavalent and the trivalent compounds, while monochromates might be responsible for the high incidence of lung cancer in the chromate industry. The chief sources of exposure are the manufacturing of chromium salts, the chrome pigment industry, chrome plating operations, and the leather industry. In all these industries there are potential hazards arising from exposure to monochromates, bichromates and chromic-acid. Skin contact results in chrome ulcer, while inhalation may result in perforation of the nasal septa and systemic disease. Workers in the photoengraving industry are exposed to ammonium-bichromate (7789095).","Industrial Exposure to Chromates in New York State Abs: The most common industrial uses of chromates in New York State and the types of exposures associated with them, are reviewed briefly. The most toxic chromium (7440473) derivatives are the hexavalent and the trivalent compounds, while monochromates might be responsible for the high incidence of lung cancer in the chromate industry. The chief sources of exposure are the manufacturing of chromium salts, the chrome pigment industry, chrome plating operations, and the leather industry. In all these industries there are potential hazards arising from exposure to monochromates, bichromates and chromic-acid. Skin contact results in chrome ulcer, while inhalation may result in perforation of the nasal septa and systemic disease. Workers in the photoengraving industry are exposed to ammonium-bichromate (7789095)."
1231280,Loewenthal 1960,Reactions in Green Tattoos,"A case of allergic reaction in a green tattoo in a bricklayer is described. Sarcoid and nonsarcoid types of foreign body granuloma occurred in adjacent clinically identical lesions. Granulomatous epidermal reactions were associated with epidermal eczematous allergic reactions. Positive patch test reactions were obtained with potassium-bichromate (7778509) and with chromic-acid (1333820), but not tetravalent chromium (7440473).","Reactions in Green Tattoos Abs: A case of allergic reaction in a green tattoo in a bricklayer is described. Sarcoid and nonsarcoid types of foreign body granuloma occurred in adjacent clinically identical lesions. Granulomatous epidermal reactions were associated with epidermal eczematous allergic reactions. Positive patch test reactions were obtained with potassium-bichromate (7778509) and with chromic-acid (1333820), but not tetravalent chromium (7440473)."
1231277,Flury 1928,Moderne Gowerbliche Vergiftungen,"The increasing incidence of occupational intoxication is discussed with reference to heavy metals, air pollutants, and organic compounds. Acetylene (74862), a gas of low toxicity, has a lethal concentration (5-10 minute inhalation) of approximately 500,000ppm, a toxic concentration of 250,000ppm, and a tolerable concentration (the latter two for 30 minute to one hour inhalations) of 100,000ppm. Severe poisoning of workers has occurred during purification of acetylene using special washing devices filled with oxidizing agents such as chloride of lime and chromic-acid (7738945). Principal symptoms include peripheral facial nerve paralyses, loss of taste and smell, corneal ulceration, and difficulties in chewing and swallowing. Lewisite and dichloroethyl-sulfide, formed by reaction of acetylene with arsenic-trichloride (7784341) and sulfur-chloride (10025679), dull the senses of taste and smell, thus impairing the perception of danger. (German)","Moderne Gowerbliche Vergiftungen Abs: The increasing incidence of occupational intoxication is discussed with reference to heavy metals, air pollutants, and organic compounds. Acetylene (74862), a gas of low toxicity, has a lethal concentration (5-10 minute inhalation) of approximately 500,000ppm, a toxic concentration of 250,000ppm, and a tolerable concentration (the latter two for 30 minute to one hour inhalations) of 100,000ppm. Severe poisoning of workers has occurred during purification of acetylene using special washing devices filled with oxidizing agents such as chloride of lime and chromic-acid (7738945). Principal symptoms include peripheral facial nerve paralyses, loss of taste and smell, corneal ulceration, and difficulties in chewing and swallowing. Lewisite and dichloroethyl-sulfide, formed by reaction of acetylene with arsenic-trichloride (7784341) and sulfur-chloride (10025679), dull the senses of taste and smell, thus impairing the perception of danger. (German)"
1231276,Schwartz et al. 1948,Dermatoses Caused by Inorganic Acids and Organic Acids,"Occupational dermatoses, burns, and skin ulcerations caused by industrial use or manufacture of acids are discussed, with chemical properties, industrial applications, type injury caused and medical treatment given for inorganic acids (sulfuric-acid (7664939), nitric-acid (7697372), hydrochloric-acid (7647010), hydrofluoric-acid (7664393), anhydrous hydrofluoric-acid, chromic-acid (7738945), phosphoric-acid (7664382)) and organic-acids (acetic-acid (64197), carbolic-acid (108952), benzoic-acid (65850), oxalic-acid (144627), ricinoleic-acid (141220), picric-acid (88891), lactic-acid (50215), formic-acid (64186), salicylic-acid (69727), phthalic-acid (88993), abietic-acid (514103), and hydrocyanic-acid (74908)).","Dermatoses Caused by Inorganic Acids and Organic Acids Abs: Occupational dermatoses, burns, and skin ulcerations caused by industrial use or manufacture of acids are discussed, with chemical properties, industrial applications, type injury caused and medical treatment given for inorganic acids (sulfuric-acid (7664939), nitric-acid (7697372), hydrochloric-acid (7647010), hydrofluoric-acid (7664393), anhydrous hydrofluoric-acid, chromic-acid (7738945), phosphoric-acid (7664382)) and organic-acids (acetic-acid (64197), carbolic-acid (108952), benzoic-acid (65850), oxalic-acid (144627), ricinoleic-acid (141220), picric-acid (88891), lactic-acid (50215), formic-acid (64186), salicylic-acid (69727), phthalic-acid (88993), abietic-acid (514103), and hydrocyanic-acid (74908))."
1231273,Wong et al. 1971,"In Vitro Metabolism Of Dimethylaminopropylthiocinnamanilide (SQ 16,167) And Its Methylureido Analogue (SQ 11,447)","The metabolism of trans-2'-dimethylaminopropylthiocinnamanilide (33464867) (SQ-16,167) and its methylureido analog SQ-11,447 were investigated in Sprague-Dawley-rats, beagle-dogs, and a human subject. Livers were obtained from the test animals and from the deceased human after autopsy. Liver homogenates was prepared and 0.25 milligram per milliliter of SQ-16,167 or SQ-11,447 was added. The resulting extracts were chromatographed and studied under ultraviolet light. Chromatograms were also sprayed with chromic-acid in order to detect compounds with primary amino groups. Similar results were obtained with liver homogenates from rats, dogs, and the human subject. For SQ-16,167, two radioactive, ultraviolet absorbing spots were observed, indicating the existence of the unchanged SQ-16,167 and dimethylaminopropylthioaniline. SQ-11,447, after chromatography, produced a single ultraviolet absorbing spot, indicating it had remained unchanged. Chromic-acid findings were consistent with the above results. The authors conclude that the amide bond of SQ-16,167, and not SQ-11,447, is hydrolyzed readily by the livers of rats, dogs, and humans.","In Vitro Metabolism Of Dimethylaminopropylthiocinnamanilide (SQ 16,167) And Its Methylureido Analogue (SQ 11,447) Abs: The metabolism of trans-2'-dimethylaminopropylthiocinnamanilide (33464867) (SQ-16,167) and its methylureido analog SQ-11,447 were investigated in Sprague-Dawley-rats, beagle-dogs, and a human subject. Livers were obtained from the test animals and from the deceased human after autopsy. Liver homogenates was prepared and 0.25 milligram per milliliter of SQ-16,167 or SQ-11,447 was added. The resulting extracts were chromatographed and studied under ultraviolet light. Chromatograms were also sprayed with chromic-acid in order to detect compounds with primary amino groups. Similar results were obtained with liver homogenates from rats, dogs, and the human subject. For SQ-16,167, two radioactive, ultraviolet absorbing spots were observed, indicating the existence of the unchanged SQ-16,167 and dimethylaminopropylthioaniline. SQ-11,447, after chromatography, produced a single ultraviolet absorbing spot, indicating it had remained unchanged. Chromic-acid findings were consistent with the above results. The authors conclude that the amide bond of SQ-16,167, and not SQ-11,447, is hydrolyzed readily by the livers of rats, dogs, and humans."
1231272,Kober and  Hanson 1916,The Printing And Publishing Industry,"Occupational diseases and hazards in the printing industry (SIC-2751) are reviewed. Diseases of the respiratory system including tuberculosis are the chief occupational diseases of those in printing. Digestive organ diseases are also found. Type metal and type founding involve exposure to lead (7439921), arsenic (7440382), and antimony (7440360). Plumbago dust inhalation or ingestion in electrotyping predisposes to diseases of the respiratory organs, but also causes lead poisoning. The compositor is chiefly exposed to the inhalation and ingestion of the dust from the type cases. Danger from type case dust can be reduced by proper handwashing and construction of the cases. The operators in monotyping and linotyping are exposed to irritating acrolein (107028) vapors from fluxing metal. Suitable hoods and exhaust flues connected to the melting pots can obviate the problem. Molten metal in stereotyping involves handling of lead and exposure to its toxic effects. Electrotyping exposes workers to irritating fumes. Workers engaged in melting new metal and old slugs are exposed to the risk of plumbism from handling metal and breathing its toxic fumes. Binding room exposures to dust, heat, and wood alcohol (67561) are injurious. Workers in chromolithography are in danger of lead poisoning. Many also suffer from visual defects. Engravers have considerable eye strain. Photoengravers are exposed to gas fumes, acids, and ammonium-dichromate (7789095). Metal etchers are exposed to chromic-acid (13530682) causing chrome ulcers. Workers in photographic facilities are exposed to contaminated air and light and to industrial poisons such as bromine (7726956). Other conditions found are bronchial irritation, erythematous rash, and eczema. The author concludes that hazards to the respiratory organs can be reduced by use of sanitary and hygenic procedures and suitable exhaust and ventilation.","The Printing And Publishing Industry Abs: Occupational diseases and hazards in the printing industry (SIC-2751) are reviewed. Diseases of the respiratory system including tuberculosis are the chief occupational diseases of those in printing. Digestive organ diseases are also found. Type metal and type founding involve exposure to lead (7439921), arsenic (7440382), and antimony (7440360). Plumbago dust inhalation or ingestion in electrotyping predisposes to diseases of the respiratory organs, but also causes lead poisoning. The compositor is chiefly exposed to the inhalation and ingestion of the dust from the type cases. Danger from type case dust can be reduced by proper handwashing and construction of the cases. The operators in monotyping and linotyping are exposed to irritating acrolein (107028) vapors from fluxing metal. Suitable hoods and exhaust flues connected to the melting pots can obviate the problem. Molten metal in stereotyping involves handling of lead and exposure to its toxic effects. Electrotyping exposes workers to irritating fumes. Workers engaged in melting new metal and old slugs are exposed to the risk of plumbism from handling metal and breathing its toxic fumes. Binding room exposures to dust, heat, and wood alcohol (67561) are injurious. Workers in chromolithography are in danger of lead poisoning. Many also suffer from visual defects. Engravers have considerable eye strain. Photoengravers are exposed to gas fumes, acids, and ammonium-dichromate (7789095). Metal etchers are exposed to chromic-acid (13530682) causing chrome ulcers. Workers in photographic facilities are exposed to contaminated air and light and to industrial poisons such as bromine (7726956). Other conditions found are bronchial irritation, erythematous rash, and eczema. The author concludes that hazards to the respiratory organs can be reduced by use of sanitary and hygenic procedures and suitable exhaust and ventilation."
1231269,Anonymous 1953,Protection Of Workers Exposed To Chromium And Its Compounds,"Methods for protection of workers exposed to chromium (7440473) and chromium compounds are reviewed. The toxicity of chromium is discussed. It is noted that not all chromium compounds are equally toxic and that the chrome colors are lead chromates; the chief toxic danger is due to lead (7439921) content. Uses of chromic-acid (13530682) in industry are described. Modes of contact of workers with chromium, chromic-acid, and its compounds are examined. The action of chromic-acid and its compounds particularly affects the skin and mucous membranes. Chrome holes (skin ulcerations), irritation of the respiratory mucous membranes with nasal ulceration and perforation of the nasal septum, and chrome dermatitis are considered. Preventive measures that can eliminate the harmful effects of chromium compounds are discussed. Segregation of operations involving chromium compounds is suggested. Effective and efficient control of chromium mists can be gained only if forced exhaust ventilation is applied near the source of dispersion. Designs for plating tanks are suggested. Such designs employ exhaust slot control, adequate hoods, or a floating baffle of plastic chips or beads. Cleanliness in work areas is necessary. Protective clothing must be well designed and fit snugly. Provisions should also be made for frequent washing of the hands. The use of protective ointments is recommended. Respirators and goggles should only be used for short duration exposures; in general, workers should be protected by other measures. Periodic medical examination of workers is recommended. Methods for determining chromates in the working environment are described. The authors suggest that the maximum allowable concentration of chromium be 1 milligram of chromic-acid anhydride in 10 cubic meters of air for exposures not exceeding 8 hours daily.","Protection Of Workers Exposed To Chromium And Its Compounds Abs: Methods for protection of workers exposed to chromium (7440473) and chromium compounds are reviewed. The toxicity of chromium is discussed. It is noted that not all chromium compounds are equally toxic and that the chrome colors are lead chromates; the chief toxic danger is due to lead (7439921) content. Uses of chromic-acid (13530682) in industry are described. Modes of contact of workers with chromium, chromic-acid, and its compounds are examined. The action of chromic-acid and its compounds particularly affects the skin and mucous membranes. Chrome holes (skin ulcerations), irritation of the respiratory mucous membranes with nasal ulceration and perforation of the nasal septum, and chrome dermatitis are considered. Preventive measures that can eliminate the harmful effects of chromium compounds are discussed. Segregation of operations involving chromium compounds is suggested. Effective and efficient control of chromium mists can be gained only if forced exhaust ventilation is applied near the source of dispersion. Designs for plating tanks are suggested. Such designs employ exhaust slot control, adequate hoods, or a floating baffle of plastic chips or beads. Cleanliness in work areas is necessary. Protective clothing must be well designed and fit snugly. Provisions should also be made for frequent washing of the hands. The use of protective ointments is recommended. Respirators and goggles should only be used for short duration exposures; in general, workers should be protected by other measures. Periodic medical examination of workers is recommended. Methods for determining chromates in the working environment are described. The authors suggest that the maximum allowable concentration of chromium be 1 milligram of chromic-acid anhydride in 10 cubic meters of air for exposures not exceeding 8 hours daily."
1231267,Van Arsdell 1947,Toxicity of Chemicals in Electroplating,"The toxic nature of compounds used in the plating industry are reviewed. The possible effects that may result from inhalation, skin contact, and ingestion of these compounds are presented. Plating operations involving silver (7440224), tin (7440315), zinc (7440666), and their respective salts are described. Different types of aqueous solutions used in electroplating are discussed, including acid, neutral, and alkaline baths. Cyanide salts are extensively used throughout the plating industry. Sodium-sulfide (1313822), ammonium-sulfide (12135761), and potassium-sulfide (1312738) are frequently encountered. In certain respects these sulfides are even more dangerous than the cyanides. Oxalic-acid (144627) is used in anodizing while hydrogen-fluoride (7664393) is used in the chromic-acid plating bath and pickling solutions. Fluosilicic-acid (16961834) and fluoroboric-acid (16872110) are used in the lead and other baths. Both contain the toxic element fluorine. Toxic reactions and first aid procedures are tabularized. The table lists the toxic action of various compounds, and appropriate first aid procedures for eye and skin contact. The author suggests that knowledge of the signs of toxic exposure can help the worker recognize a hazardous situation before too much damage occurs.","Toxicity of Chemicals in Electroplating Abs: The toxic nature of compounds used in the plating industry are reviewed. The possible effects that may result from inhalation, skin contact, and ingestion of these compounds are presented. Plating operations involving silver (7440224), tin (7440315), zinc (7440666), and their respective salts are described. Different types of aqueous solutions used in electroplating are discussed, including acid, neutral, and alkaline baths. Cyanide salts are extensively used throughout the plating industry. Sodium-sulfide (1313822), ammonium-sulfide (12135761), and potassium-sulfide (1312738) are frequently encountered. In certain respects these sulfides are even more dangerous than the cyanides. Oxalic-acid (144627) is used in anodizing while hydrogen-fluoride (7664393) is used in the chromic-acid plating bath and pickling solutions. Fluosilicic-acid (16961834) and fluoroboric-acid (16872110) are used in the lead and other baths. Both contain the toxic element fluorine. Toxic reactions and first aid procedures are tabularized. The table lists the toxic action of various compounds, and appropriate first aid procedures for eye and skin contact. The author suggests that knowledge of the signs of toxic exposure can help the worker recognize a hazardous situation before too much damage occurs."
1231266,Stratton 1950,Health and Industrial Hazards in the Plating Industry,"Hazards which cause industrial accidents and health hazards in the plating industry (SIC-3471) are reviewed. Physical safety hazards such as wet conditions, and improper equipment, storage, and wiring are cited; and precautionary measures are reviewed, including the use and proper installation of good equipment, provision of personal protective equipment and safety devices, and establishment of an effective accident control program. Worker health hazards also are addressed, and operations involving potential chemical exposure hazards are described, such as grinding, polishing, buffing, degreasing, and wet cleaning. Specific hazards from toxic metals, solvents, damp environments, chromic-acid (1308141) poor ventilation, and cyanamide (74908) exposure are identified. National Safety Council recommendations which can be adapted to individual factory programs are examined. Hazards outside the factory, such as stream pollution, are considered. The author recommends methods of control of hazardous exposures in the electroplating industry, including provision of good equipment and operating conditions, use of good housekeeping practices, and implementation of an adequate managerial safety program.","Health and Industrial Hazards in the Plating Industry Abs: Hazards which cause industrial accidents and health hazards in the plating industry (SIC-3471) are reviewed. Physical safety hazards such as wet conditions, and improper equipment, storage, and wiring are cited; and precautionary measures are reviewed, including the use and proper installation of good equipment, provision of personal protective equipment and safety devices, and establishment of an effective accident control program. Worker health hazards also are addressed, and operations involving potential chemical exposure hazards are described, such as grinding, polishing, buffing, degreasing, and wet cleaning. Specific hazards from toxic metals, solvents, damp environments, chromic-acid (1308141) poor ventilation, and cyanamide (74908) exposure are identified. National Safety Council recommendations which can be adapted to individual factory programs are examined. Hazards outside the factory, such as stream pollution, are considered. The author recommends methods of control of hazardous exposures in the electroplating industry, including provision of good equipment and operating conditions, use of good housekeeping practices, and implementation of an adequate managerial safety program."
1231265,Molos 1947,Health Hazards in the Electroplating Industry,"Health hazards in the electroplating industry are reviewed. Hazards due to ingestion of dangerous substances are discussed, and the rarity of poisonings by this route is noted. Hazards from skin contact are described. Work process operations in which workers are exposed to hazardous chemicals are reviewed, including degreasing and lacquering processes. The use of protective clothing, washing facilities, and protective creams is discussed for prevention of skin contact. Also described are hazards due to contamination of the plating room atmosphere by vapors, mists, gases, fumes, and dusts. Local exhaust ventilation is discussed as a means of contamination control. Generation of chromic-acid (1308141) during chromium (7440473) plating operations is explained, and the use of floating plastic chips over a chromium plating tank to reduce atmospheric chromic-acid is evaluated. Potential hazards due to formation of hydrogen-cyanide gas are considered, and problems also are discussed in relation to cleaning, degreasing, pickling, and anodizing operations. Production of dusts during sandblasting, grinding, buffing, and polishing processes is reviewed. The author concludes that progress has been made in overcoming health hazards in the electroplating industry.","Health Hazards in the Electroplating Industry Abs: Health hazards in the electroplating industry are reviewed. Hazards due to ingestion of dangerous substances are discussed, and the rarity of poisonings by this route is noted. Hazards from skin contact are described. Work process operations in which workers are exposed to hazardous chemicals are reviewed, including degreasing and lacquering processes. The use of protective clothing, washing facilities, and protective creams is discussed for prevention of skin contact. Also described are hazards due to contamination of the plating room atmosphere by vapors, mists, gases, fumes, and dusts. Local exhaust ventilation is discussed as a means of contamination control. Generation of chromic-acid (1308141) during chromium (7440473) plating operations is explained, and the use of floating plastic chips over a chromium plating tank to reduce atmospheric chromic-acid is evaluated. Potential hazards due to formation of hydrogen-cyanide gas are considered, and problems also are discussed in relation to cleaning, degreasing, pickling, and anodizing operations. Production of dusts during sandblasting, grinding, buffing, and polishing processes is reviewed. The author concludes that progress has been made in overcoming health hazards in the electroplating industry."
1231264,Greenberg and  Lester 1944,A Micromethod for the Determination of Acetone and Ketone Bodies,"A method for the determination of acetone (67641) and ketones in blood and urine was evaluated. The solution to be analyzed along with 2 cubic centimeters (cc) of carbon-tetrachloride was added to 2cc of 2,4-dinitrophenylhydrazine. After shaking, the supernatant drawn off and the remaining contents were read colorimetrically and compared with carbon-tetrachloride readings. To determine ketone in blood and urine, a micro refluxing tube was used to maintain stable concentrations of sulfuric-acid (7664939) and dichromate (13907476) in the solution to extract acetone from the ketones. The amount of acetone-hydrazone (5281209) recovered from carbon-tetrachloride was less than that formed from the acetone hydrazine reaction. In blood and urine, the concentration of acetone obtained did not represent all ketone bodies, since only 86 percent of hydroxybutyric-acid formed from the dichromic-acid was oxidized to acetone. The authors conclude that the method is rapid, sensitive, and accurate for determining acetone content and determining ketone bodies.","A Micromethod for the Determination of Acetone and Ketone Bodies Abs: A method for the determination of acetone (67641) and ketones in blood and urine was evaluated. The solution to be analyzed along with 2 cubic centimeters (cc) of carbon-tetrachloride was added to 2cc of 2,4-dinitrophenylhydrazine. After shaking, the supernatant drawn off and the remaining contents were read colorimetrically and compared with carbon-tetrachloride readings. To determine ketone in blood and urine, a micro refluxing tube was used to maintain stable concentrations of sulfuric-acid (7664939) and dichromate (13907476) in the solution to extract acetone from the ketones. The amount of acetone-hydrazone (5281209) recovered from carbon-tetrachloride was less than that formed from the acetone hydrazine reaction. In blood and urine, the concentration of acetone obtained did not represent all ketone bodies, since only 86 percent of hydroxybutyric-acid formed from the dichromic-acid was oxidized to acetone. The authors conclude that the method is rapid, sensitive, and accurate for determining acetone content and determining ketone bodies."
1231263,Heasman and  Baldwin 1986,THE DESTRUCTION OF CHRYSOTILE ASBESTOS USING WASTE ACIDS,"HMTC A mixed nitric acid-chromic acid waste, a sulphuric acid waste, and a mixed sulphuric, hydrochloric, nitric, and chromic acid waste were used to degrade chrysotile asbestos, the major asbestos used in the United Kingdom. The release of magnesium, the major cation present in the asbestos tested, was the main experimental parameter. All samples were examined microscopically after acid exposure. Given sufficient time, 100% of the magnesium was leached from the asbestos by each waste acid tested. With nitricchromic acid, 80 +/- 20% of the magnesium was leached with an hour of shaking, while 1-2 days were required to leach 80 +/- 20% of the magnesium using the mixed acid waste. Up to 15 days were required to leach 80 +/- 20% of the magnesium using the sulphuric acid waste. Some fibrous residue remained after treatment with each type of acid waste. (15 ref.)","THE DESTRUCTION OF CHRYSOTILE ASBESTOS USING WASTE ACIDS Abs: HMTC A mixed nitric acid-chromic acid waste, a sulphuric acid waste, and a mixed sulphuric, hydrochloric, nitric, and chromic acid waste were used to degrade chrysotile asbestos, the major asbestos used in the United Kingdom. The release of magnesium, the major cation present in the asbestos tested, was the main experimental parameter. All samples were examined microscopically after acid exposure. Given sufficient time, 100% of the magnesium was leached from the asbestos by each waste acid tested. With nitricchromic acid, 80 +/- 20% of the magnesium was leached with an hour of shaking, while 1-2 days were required to leach 80 +/- 20% of the magnesium using the mixed acid waste. Up to 15 days were required to leach 80 +/- 20% of the magnesium using the sulphuric acid waste. Some fibrous residue remained after treatment with each type of acid waste. (15 ref.)"
1231262,Gardner and  Huisingh 1987,WASTE REDUCTION THROUGH MATERIAL AND PROCESS SUBSTITUTIONS: PROGRESS AND PROBLEMS ENCOUNTERED IN INDUSTRIAL IMPLEMENTATION,"HMTC Eleven examples of material and process substitutions that have reduced hazardous waste production are examined. Case studies provide information on replacing chlorinated with water-based degreasers; caustic metal cleaners with a pneumatic system; caustic metal cleaners with a high-pressure, hot-water, closedloop system; acidic metal cleaners with mechanical abrasion cleaners; chromic acid bright dip with sulfuric acid/peroxide dip; acidic methylene chloride paint with pneumatic paint stripping operations; mercury with selective membranes; cadmiumcontaining pigments with pigments that are less toxic; organic-based paint with water-based paint in metal coating; organic solvent-based coating with water-based coating in the pharmaceutical industry; and organic-based ink with water-based ink. Inequitable regulations and uneven enforcement prevent many companies from attempting material and process substitutions. (40 ref.)","WASTE REDUCTION THROUGH MATERIAL AND PROCESS SUBSTITUTIONS: PROGRESS AND PROBLEMS ENCOUNTERED IN INDUSTRIAL IMPLEMENTATION Abs: HMTC Eleven examples of material and process substitutions that have reduced hazardous waste production are examined. Case studies provide information on replacing chlorinated with water-based degreasers; caustic metal cleaners with a pneumatic system; caustic metal cleaners with a high-pressure, hot-water, closedloop system; acidic metal cleaners with mechanical abrasion cleaners; chromic acid bright dip with sulfuric acid/peroxide dip; acidic methylene chloride paint with pneumatic paint stripping operations; mercury with selective membranes; cadmiumcontaining pigments with pigments that are less toxic; organic-based paint with water-based paint in metal coating; organic solvent-based coating with water-based coating in the pharmaceutical industry; and organic-based ink with water-based ink. Inequitable regulations and uneven enforcement prevent many companies from attempting material and process substitutions. (40 ref.)"
1231261,Brooks 1985,METAL RECOVERY FROM WASTE ACIDS,"HMTC Bench-scale evaluation tests to determine the feasibility of separating metals, such as nickel, copper, and zinc, in the presence of chromium and iron from industrial waste pickling acids have been conducted. The separation concept evaluated consisted of adjusting the pH of the waste acids with alkalis to a moderate acid range of 2 to 5 to precipitate the bulk of the iron, followed by separation of the nickel, copper, and zinc using solvent extraction with lauric acid/xylene, cation exchange with a hydrogen resin, and precipitate flotation with lauric acid and sodium lauryl sulfate. Solvent extraction with a lauric acid/ xylene solution of the waste acid mixtures adjusted to a pH range of 2 to 5 yielded a greater than 67% separation of nickel and copper for chromic acid and the acidified sludges. (13 ref.)","METAL RECOVERY FROM WASTE ACIDS Abs: HMTC Bench-scale evaluation tests to determine the feasibility of separating metals, such as nickel, copper, and zinc, in the presence of chromium and iron from industrial waste pickling acids have been conducted. The separation concept evaluated consisted of adjusting the pH of the waste acids with alkalis to a moderate acid range of 2 to 5 to precipitate the bulk of the iron, followed by separation of the nickel, copper, and zinc using solvent extraction with lauric acid/xylene, cation exchange with a hydrogen resin, and precipitate flotation with lauric acid and sodium lauryl sulfate. Solvent extraction with a lauric acid/ xylene solution of the waste acid mixtures adjusted to a pH range of 2 to 5 yielded a greater than 67% separation of nickel and copper for chromic acid and the acidified sludges. (13 ref.)"
1231260,Tencer 1983,TOXIC METALS NO.4: CHROMIUM,"HMTC Chromium and its compounds are widely used in plating, as an alloying metal, corrosion inhibitive paint, tanning agent, wood preservative, paint pigment, fixative in wool dying and in photography. Exposures to chromium among Navy workers include chromic acid mists generated during electroplating and in the spraying of chromate-containing paints. Other less significant exposures, to hexavalent chromium occurs in the cutting or welding of chromiumcontaining steels. The skin is the main route of entry of chromium compounds. Although inhalation is not as common, it occurs during some plating operations and during the spraying of chromatecontaining paints. Excessive exposure results in symptoms such as chromate dermatitis--a rash resembling eczema. Chronic long term exposure often produces skin ulcers. Inhalation of chromic acid and chromates can cause gradual erosion of the nasal lining, cartilage perforation, and inflammation and ulceration of the larynx with occasional vocal cord involvement. Chronic inhalation of water-insoluble chromates is a suspect cause of human bronchial cancer (which has a latency period of 2025 years). Current Threshold Limit Value as an eight-hour time-weighted average is 0.5 milligrams per cubic meter of air for divalent and trivalent chromium, and 0.05 milligrams for hexavalent chromium.","TOXIC METALS NO.4: CHROMIUM Abs: HMTC Chromium and its compounds are widely used in plating, as an alloying metal, corrosion inhibitive paint, tanning agent, wood preservative, paint pigment, fixative in wool dying and in photography. Exposures to chromium among Navy workers include chromic acid mists generated during electroplating and in the spraying of chromate-containing paints. Other less significant exposures, to hexavalent chromium occurs in the cutting or welding of chromiumcontaining steels. The skin is the main route of entry of chromium compounds. Although inhalation is not as common, it occurs during some plating operations and during the spraying of chromatecontaining paints. Excessive exposure results in symptoms such as chromate dermatitis--a rash resembling eczema. Chronic long term exposure often produces skin ulcers. Inhalation of chromic acid and chromates can cause gradual erosion of the nasal lining, cartilage perforation, and inflammation and ulceration of the larynx with occasional vocal cord involvement. Chronic inhalation of water-insoluble chromates is a suspect cause of human bronchial cancer (which has a latency period of 2025 years). Current Threshold Limit Value as an eight-hour time-weighted average is 0.5 milligrams per cubic meter of air for divalent and trivalent chromium, and 0.05 milligrams for hexavalent chromium."
1231246,Horiguchi et al. 1980,Industrial chromium poisoning in the small and medium sized electroplating factories: 2,"HEEP COPYRIGHT: BIOL ABS. Actual conditions of Cr electro-plating factories manufacturing bicycle parts in S city near Osaka (Japan) were surveyed 20 yr ago. One factory was visited in Aug., 1977 to observe changes during the past 20 yr. Automation of the plating process and changes of plating method lowered the degree of workers' exposure to chromic acid and dusts.","Industrial chromium poisoning in the small and medium sized electroplating factories: 2 Abs: HEEP COPYRIGHT: BIOL ABS. Actual conditions of Cr electro-plating factories manufacturing bicycle parts in S city near Osaka (Japan) were surveyed 20 yr ago. One factory was visited in Aug., 1977 to observe changes during the past 20 yr. Automation of the plating process and changes of plating method lowered the degree of workers' exposure to chromic acid and dusts."
1231245,Beaulieu et al. 1980,A comparison of aerosol sampling techniques: Open vs. closed-face filter cassettes,"HEEP COPYRIGHT: BIOL ABS. Accepted practice by most professional industrial hygienists in government and industry is to use closed-face filter cassette techniques as standard sampling procedures for the majority of aerosols. A 2-phase field study was conducted to determine whether a gravimetric bias exists between open- and closed-face sampling methods. Phase I involved an in-depth analysis of the potential gravimetric viability as it applies to an industrial paint spray mist, and Phase II was a series of pilot studies, of small sample base, to determine if this phenomena exists over a range of aerosol types. Dusts of wood, grain, cellulose, Portland cement and perlite, welding fumes and chromic acid mist were sampled in Phase II. Paired breathing zone samples, open- and closed-face, 37 mm, 3-piece filter cassettes were utilized in both phases of the study; open-face concentrations were consistently higher than closed-face concentrations, with the exception of cellulose dust. Based on the concentration for both sampling techniques, the data suggest that closed-face sampling techniques (4.0 mm inlet diameter) might be size selective against large particles. This could lead to an underestimation of a worker's total aerosol exposure.","A comparison of aerosol sampling techniques: Open vs. closed-face filter cassettes Abs: HEEP COPYRIGHT: BIOL ABS. Accepted practice by most professional industrial hygienists in government and industry is to use closed-face filter cassette techniques as standard sampling procedures for the majority of aerosols. A 2-phase field study was conducted to determine whether a gravimetric bias exists between open- and closed-face sampling methods. Phase I involved an in-depth analysis of the potential gravimetric viability as it applies to an industrial paint spray mist, and Phase II was a series of pilot studies, of small sample base, to determine if this phenomena exists over a range of aerosol types. Dusts of wood, grain, cellulose, Portland cement and perlite, welding fumes and chromic acid mist were sampled in Phase II. Paired breathing zone samples, open- and closed-face, 37 mm, 3-piece filter cassettes were utilized in both phases of the study; open-face concentrations were consistently higher than closed-face concentrations, with the exception of cellulose dust. Based on the concentration for both sampling techniques, the data suggest that closed-face sampling techniques (4.0 mm inlet diameter) might be size selective against large particles. This could lead to an underestimation of a worker's total aerosol exposure."
1231244,Grant et al. 1980,"Terpenoid chemistry: 24. (1R)-1-Methoxymyodesert-3-ene, an iridoid constituent of Myoporum deserti (Myoporaceae)","HEEP COPYRIGHT: BIOL ABS. A common variety of M. deserti (Ellangowan Poison Bush) (a stock poison) yields an essential oil consisting largely of the iridoid monoterpene, (1R)-1-methoxymyodesert-3-ene, C11H18O2, (1R,4aS,7R,7aR)-1-methoxy-4,7-dimethyl-1,4a, 5,6,7,7a-hexahydrocyclopenta(c)pyran, boiling point 67?/2 mm, (alpha)D-165?. This cyclic acetal is hydrolyzed to methanol and a mixture of 2 epimeric cyclopentanoid dialdehydes which are oxidized to the 2 epimeric trans,trans-nepetalinic acids and yield (+)-(R)-actinidine with Brady's reagent. (1R)-1-Methoxymyodesert-3-ene is oxidized by ozone/hydrogen peroxide to (1R,2R,5R)-2-acetyl-5-methylcyclopentanecarboxylic acid. Hydrogenation yields mainly (1R)-methoxymyodesertan, hydrolyzed by aqueous maleic acid at room temperature to methanol and a cyclic hemiacetal, (1R,4R,4aR,7R,7aR)-4,7-dimethyl-1,3,4,4a,5,6,7,7a-octahydrocyclopenta(c)pyran-1-ol. Oxidation of this cis-cis-hemiacetal by bromine in acetate buffer yields a lactone further oxidized by chromic acid to (2R,1'S,2'R,3'R)-2-(2'-carboxy-3'-methylcyclopentyl)-propionic acid. (1R)-1-Methoxymyodesertan, refluxed with aqueous phthalic acid, yields (+)-(4R,4aR,7R)-4,7-dimethyl-3,4,4a,5,6,7-hexahydrocyclopenta(c)pyran. Treatment of the hexahydropenta(c)pyran, the cis,cis-hemiacetal or (1R)-1-methoxymyodesertan with hydrochloric acid yields a trans,trans-hemiacetal, (1R,4R,4aR,7R,7aS)-4,7-dimethyl-1,3,4,4a,5,6,7,7a-octahydrocyclopenta(c)pyran-1-ol, which equilibrates in solution to a mixture of alpha- and beta-anomers. Spectral studies of these and other products establish the configuration of the natural product at C1. (1R)-1-Methoxymyodesert-3-ene is not toxic to sheep as are the beta-substituted furans characteristic of most other chemovarieties of M. deserti.","Terpenoid chemistry: 24. (1R)-1-Methoxymyodesert-3-ene, an iridoid constituent of Myoporum deserti (Myoporaceae) Abs: HEEP COPYRIGHT: BIOL ABS. A common variety of M. deserti (Ellangowan Poison Bush) (a stock poison) yields an essential oil consisting largely of the iridoid monoterpene, (1R)-1-methoxymyodesert-3-ene, C11H18O2, (1R,4aS,7R,7aR)-1-methoxy-4,7-dimethyl-1,4a, 5,6,7,7a-hexahydrocyclopenta(c)pyran, boiling point 67?/2 mm, (alpha)D-165?. This cyclic acetal is hydrolyzed to methanol and a mixture of 2 epimeric cyclopentanoid dialdehydes which are oxidized to the 2 epimeric trans,trans-nepetalinic acids and yield (+)-(R)-actinidine with Brady's reagent. (1R)-1-Methoxymyodesert-3-ene is oxidized by ozone/hydrogen peroxide to (1R,2R,5R)-2-acetyl-5-methylcyclopentanecarboxylic acid. Hydrogenation yields mainly (1R)-methoxymyodesertan, hydrolyzed by aqueous maleic acid at room temperature to methanol and a cyclic hemiacetal, (1R,4R,4aR,7R,7aR)-4,7-dimethyl-1,3,4,4a,5,6,7,7a-octahydrocyclopenta(c)pyran-1-ol. Oxidation of this cis-cis-hemiacetal by bromine in acetate buffer yields a lactone further oxidized by chromic acid to (2R,1'S,2'R,3'R)-2-(2'-carboxy-3'-methylcyclopentyl)-propionic acid. (1R)-1-Methoxymyodesertan, refluxed with aqueous phthalic acid, yields (+)-(4R,4aR,7R)-4,7-dimethyl-3,4,4a,5,6,7-hexahydrocyclopenta(c)pyran. Treatment of the hexahydropenta(c)pyran, the cis,cis-hemiacetal or (1R)-1-methoxymyodesertan with hydrochloric acid yields a trans,trans-hemiacetal, (1R,4R,4aR,7R,7aS)-4,7-dimethyl-1,3,4,4a,5,6,7,7a-octahydrocyclopenta(c)pyran-1-ol, which equilibrates in solution to a mixture of alpha- and beta-anomers. Spectral studies of these and other products establish the configuration of the natural product at C1. (1R)-1-Methoxymyodesert-3-ene is not toxic to sheep as are the beta-substituted furans characteristic of most other chemovarieties of M. deserti."
1231239,Ito et al. 1978,A survey on environmental control in gilding factories,"HEEP COPYRIGHT: BIOL ABS. The recent revision and enforcement of the regulations dealing with labor hygiene improved environmental control in factories where chemical substances were used. In gilding factories, facilities for drainage and general hygiene in the labor environment improved since environmental pollution regulations were enforced. Most of these factories were small and 41.4% of them had 9 employees or less. The environmental control was conducted by an internal organization. Based on assessment data, the present study was performed to investigate the environmental control of chromic acid in those factories. The concentration of Cr was satisfactorily low and 97.75% of all factories showed 1/10 or less of the tolerable concentration. Exposure to the high Cr concentration for a short period is possible depending on the type of work, and the exposure concentration differs depending on the surface area of the gilding tank, the concentration and temperature of the gilding solution and the electric capacity. Labor hygiene problems which must be solved still remain although the environmental concentration of Cr is low. The current regulations require the assessment of chromic acid twice a year. Even in the same factory the concentration measured in summer and winter differed by 1:2.8. Because of the poor ventilation in the factory high concentrations were occasionally detected in winter. Although the number of cases studied was insufficient, the regular assessment of chromic acid should be performed in summer and winter.","A survey on environmental control in gilding factories Abs: HEEP COPYRIGHT: BIOL ABS. The recent revision and enforcement of the regulations dealing with labor hygiene improved environmental control in factories where chemical substances were used. In gilding factories, facilities for drainage and general hygiene in the labor environment improved since environmental pollution regulations were enforced. Most of these factories were small and 41.4% of them had 9 employees or less. The environmental control was conducted by an internal organization. Based on assessment data, the present study was performed to investigate the environmental control of chromic acid in those factories. The concentration of Cr was satisfactorily low and 97.75% of all factories showed 1/10 or less of the tolerable concentration. Exposure to the high Cr concentration for a short period is possible depending on the type of work, and the exposure concentration differs depending on the surface area of the gilding tank, the concentration and temperature of the gilding solution and the electric capacity. Labor hygiene problems which must be solved still remain although the environmental concentration of Cr is low. The current regulations require the assessment of chromic acid twice a year. Even in the same factory the concentration measured in summer and winter differed by 1:2.8. Because of the poor ventilation in the factory high concentrations were occasionally detected in winter. Although the number of cases studied was insufficient, the regular assessment of chromic acid should be performed in summer and winter."
1231236,Kieszkowski and  Jackson 1978,A clean water project in Poland,"HEEP COPYRIGHT: BIOL ABS. The major environmental problems in the metal finishing industry in Poland consist of wastewater pollution and air pollution, as well as large amounts of metal-bearing sludge from effluent treatment process. The wastewaters produced in metal finishing operations contain many toxic pollutants, such as cyanides, chromates, heavy metals, mineral acids, alkalis, oils, greases, detergents and organic solvents. The most common and generally employed effluent treatment technology consists of well-known, conventional chemical procedures that can be done both continuously and batch-wise. Most of the large plating shops are equipped with fully or partially automatic continuous, conventional effluent treatment plants. As far as air pollution control in plating shops is concerned, dry scrubbers are used to deal with chromic acid mist from chrome plating operations. However, sometimes wet scrubbers are used to absorb nitrogen oxide fumes from brass bright-dip operations. Much more important air pollution problems are encountered in the organic coatings industry, especially in paint shops. A serious environmental problem is created by the increasing amounts of heavy metals contained in watered sludge from effluent treatment operations, as well as organic sludges from spray paint application. The most promising newer effluent treatment and material recovery techniques, suitable to the Polish metal finishing conditions and necessary for better environmental protection, are discussed.","A clean water project in Poland Abs: HEEP COPYRIGHT: BIOL ABS. The major environmental problems in the metal finishing industry in Poland consist of wastewater pollution and air pollution, as well as large amounts of metal-bearing sludge from effluent treatment process. The wastewaters produced in metal finishing operations contain many toxic pollutants, such as cyanides, chromates, heavy metals, mineral acids, alkalis, oils, greases, detergents and organic solvents. The most common and generally employed effluent treatment technology consists of well-known, conventional chemical procedures that can be done both continuously and batch-wise. Most of the large plating shops are equipped with fully or partially automatic continuous, conventional effluent treatment plants. As far as air pollution control in plating shops is concerned, dry scrubbers are used to deal with chromic acid mist from chrome plating operations. However, sometimes wet scrubbers are used to absorb nitrogen oxide fumes from brass bright-dip operations. Much more important air pollution problems are encountered in the organic coatings industry, especially in paint shops. A serious environmental problem is created by the increasing amounts of heavy metals contained in watered sludge from effluent treatment operations, as well as organic sludges from spray paint application. The most promising newer effluent treatment and material recovery techniques, suitable to the Polish metal finishing conditions and necessary for better environmental protection, are discussed."
1231234,Yartseva et al. 1975,Synthesis of 1-glucosylisatins and their biological activity in animals with transplantable tumors and in in vitro systems,"HEEP COPYRIGHT: BIOL ABS. A new method of synthesis of 1-glycosylisatins by oxidation of O-acylated 1-glycosylindoles or 1-glycosylindolines by chromic acid is proposed. The oxidation of 1-beta-D-2',3',4',6-tetra-O-acetylglucopyranosylindole or 1-beta-D-2',3',4',6'-tetra-O-acetyglucopyranosylindoline furnished 1-beta-D-2',3',4',6'-tetra-O-acetyglucopyranosylisatin. The thiosemicarbazones of 1-glucopuranosylisatin or 1-glycopyranosylmethylisatins stimulate the growth of mouse adenocarcinoma 755.","Synthesis of 1-glucosylisatins and their biological activity in animals with transplantable tumors and in in vitro systems Abs: HEEP COPYRIGHT: BIOL ABS. A new method of synthesis of 1-glycosylisatins by oxidation of O-acylated 1-glycosylindoles or 1-glycosylindolines by chromic acid is proposed. The oxidation of 1-beta-D-2',3',4',6-tetra-O-acetylglucopyranosylindole or 1-beta-D-2',3',4',6'-tetra-O-acetyglucopyranosylindoline furnished 1-beta-D-2',3',4',6'-tetra-O-acetyglucopyranosylisatin. The thiosemicarbazones of 1-glucopuranosylisatin or 1-glycopyranosylmethylisatins stimulate the growth of mouse adenocarcinoma 755."
1231229,Berge and  Jaag 1973,"The nonparasitic diseases. Immission damage (gas, smoke and dust damage). Waste water damage including damage caused by solid wastes","HEEP COPYRIGHT: BIOL ABS. Aspects of protection for a wide range of plants, expecially cultivated plants, against immissions are discussed. Immissions include SO2 fluoride compounds, ammonia, H2S, nitrous gases, H2SO4, chromic acid, smog and peroxyacetyl nitrate, nitrite, lime, alkali, basalt, metal, arsenic and grain dusts, and ashes. The damage to the plants, their mode of effect, plant resistance and determination of these immissions in the atmosphere are discussed. The effect of waste water and solid wastes on plants and soil, the fertilizer value of some household and industrial wastewater and damage caused by alkali salts, trace elements, organic substances, detergents, radioisotopes, compost, sewage sludge, mineral oil products and solid industrial wastes are also discussed. An extensive bibliography is included at the end of each section.","The nonparasitic diseases. Immission damage (gas, smoke and dust damage). Waste water damage including damage caused by solid wastes Abs: HEEP COPYRIGHT: BIOL ABS. Aspects of protection for a wide range of plants, expecially cultivated plants, against immissions are discussed. Immissions include SO2 fluoride compounds, ammonia, H2S, nitrous gases, H2SO4, chromic acid, smog and peroxyacetyl nitrate, nitrite, lime, alkali, basalt, metal, arsenic and grain dusts, and ashes. The damage to the plants, their mode of effect, plant resistance and determination of these immissions in the atmosphere are discussed. The effect of waste water and solid wastes on plants and soil, the fertilizer value of some household and industrial wastewater and damage caused by alkali salts, trace elements, organic substances, detergents, radioisotopes, compost, sewage sludge, mineral oil products and solid industrial wastes are also discussed. An extensive bibliography is included at the end of each section."
1231228,Henning 1972,Chromium plating,Chrome liquors in contact with the skin can cause dermatitis or ulceration. Personal hygiene and the use of suitable protective clothing can prevent this. Chromic acid mist given off during processing can attack the nose leading to ulceration and eventually perforation of the nasal septum. Personal hygiene has a part to play in the prevention of nasal ulceration but the effective solution is to prevent the chromic acid mist from entering the air of the workroom. This can be achieved by the installation and use of correctly designed lip exhaust ventilation. Alternatively the emission of the spray can be prevented by the use of chemical suppressants which act either by reducing the surface tension of the liquid or by building up a layer of foam to act as a physical barrier.,Chromium plating Abs: Chrome liquors in contact with the skin can cause dermatitis or ulceration. Personal hygiene and the use of suitable protective clothing can prevent this. Chromic acid mist given off during processing can attack the nose leading to ulceration and eventually perforation of the nasal septum. Personal hygiene has a part to play in the prevention of nasal ulceration but the effective solution is to prevent the chromic acid mist from entering the air of the workroom. This can be achieved by the installation and use of correctly designed lip exhaust ventilation. Alternatively the emission of the spray can be prevented by the use of chemical suppressants which act either by reducing the surface tension of the liquid or by building up a layer of foam to act as a physical barrier.
1231227,Fregert et al. 1971,Sensitization to chromium and cobalt in processing of sulphage pulp,"HEEP COPYRIGHT: BIOL ABS. Two men working in the recovery process in a sulfate pulp factory developed eczema on their hands and faces. Both gave positive reactions to Cr and 1 also to Co at routine patch testing. This finding initiated examination of samples from different stages. In samples from the recovery process, both tri-and hexa-valent Cr and Co were found. The Cr is oxidized to hexavalent form in the lime kiln. The Cr and Co seem to be added to the process as Na2SO4, CaO and CaCO3, used as make-up chemicals. The content of Cr varied considerably. The highest content, 3300 mug Cr-6/g, was found in a special form of Na2SO4, chrome-cake, obtained as a by-product of production of chromic acid. Such Na2SO4 must not be used in pulp factories. Cr was also found in Na2SO4 of high technical and of pro analysis quality. This substance also occurs in detergents and is used in the determination of absorbed chromate in cement.","Sensitization to chromium and cobalt in processing of sulphage pulp Abs: HEEP COPYRIGHT: BIOL ABS. Two men working in the recovery process in a sulfate pulp factory developed eczema on their hands and faces. Both gave positive reactions to Cr and 1 also to Co at routine patch testing. This finding initiated examination of samples from different stages. In samples from the recovery process, both tri-and hexa-valent Cr and Co were found. The Cr is oxidized to hexavalent form in the lime kiln. The Cr and Co seem to be added to the process as Na2SO4, CaO and CaCO3, used as make-up chemicals. The content of Cr varied considerably. The highest content, 3300 mug Cr-6/g, was found in a special form of Na2SO4, chrome-cake, obtained as a by-product of production of chromic acid. Such Na2SO4 must not be used in pulp factories. Cr was also found in Na2SO4 of high technical and of pro analysis quality. This substance also occurs in detergents and is used in the determination of absorbed chromate in cement."
1231215,Barker 1998,STORAGE AND DISPOSAL,BIOSIS COPYRIGHT: BIOL ABS. RRM BOOK CHAPTER LAB WASTE DISPOSAL REFRIGERATORS FREEZERS REAGENT STORAGE EMERGENCY STORAGE ALIQUOTING ACIDS STORAGE DISPOSAL BASES MONOCLONAL ANTIBODIES POLYCLONAL ANTIBODIES DETERGENTS BUFFERS DNA ENZYMES ETHANOL GROWTH FACTORS CYTOKINES HAZARDOUS CHEMICALS LIPIDS MEDIA RADIOISOTOPES RNA SERUM METHODOLOGY BIOCHEMISTRY AND BIOPHYSICS DISPOSAL METHOD LABORATORY EQUIPMENT STORAGE METHOD LABORATORY METHOD BLOOD AND LYMPHATICS,STORAGE AND DISPOSAL Abs: BIOSIS COPYRIGHT: BIOL ABS. RRM BOOK CHAPTER LAB WASTE DISPOSAL REFRIGERATORS FREEZERS REAGENT STORAGE EMERGENCY STORAGE ALIQUOTING ACIDS STORAGE DISPOSAL BASES MONOCLONAL ANTIBODIES POLYCLONAL ANTIBODIES DETERGENTS BUFFERS DNA ENZYMES ETHANOL GROWTH FACTORS CYTOKINES HAZARDOUS CHEMICALS LIPIDS MEDIA RADIOISOTOPES RNA SERUM METHODOLOGY BIOCHEMISTRY AND BIOPHYSICS DISPOSAL METHOD LABORATORY EQUIPMENT STORAGE METHOD LABORATORY METHOD BLOOD AND LYMPHATICS
1231211,Titford 1996,Safety considerations in the use of silver stains,"BIOSIS COPYRIGHT: BIOL ABS. Silver stains are commonly used in histology laboratories to demonstrate a variety of tissue substances. With the passage of time, it has become evident that several of the chemicals used in silver stains, as well as silver compounds themselves, pose hazards to laboratory workers. Disposal of these chemicals also poses a problem. This article briefly outlines some of the hazards of working with the chemicals used in silver stains. A comprehensive chemical hygiene plan, which must be developed for each laboratory, provides a standard operating procedure for working safely with chemicals. Material safety data sheets provide information on each chemical used in the laboratory and must be available. The use of several of the chemicals employed in silver stains is covered by Federal, state, and local laws. The state and local laws may be more stringent than the Federal laws.","Safety considerations in the use of silver stains Abs: BIOSIS COPYRIGHT: BIOL ABS. Silver stains are commonly used in histology laboratories to demonstrate a variety of tissue substances. With the passage of time, it has become evident that several of the chemicals used in silver stains, as well as silver compounds themselves, pose hazards to laboratory workers. Disposal of these chemicals also poses a problem. This article briefly outlines some of the hazards of working with the chemicals used in silver stains. A comprehensive chemical hygiene plan, which must be developed for each laboratory, provides a standard operating procedure for working safely with chemicals. Material safety data sheets provide information on each chemical used in the laboratory and must be available. The use of several of the chemicals employed in silver stains is covered by Federal, state, and local laws. The state and local laws may be more stringent than the Federal laws."
1231209,Sullivan et al. 1995,RESPIRATORY DISEASE RISKS IN THE CONSTRUCTION INDUSTRY,BIOSIS COPYRIGHT: BIOL ABS. RRM LITERATURE REVIEW HUMAN LUNG CANCER PLEURAL FIBROSIS OCCUPATIONAL ASTHMA RESPIRATORY INFECTIONS RESPIRATORY DISTRESS SYNDROME MORBIDITY CHEMICALS,RESPIRATORY DISEASE RISKS IN THE CONSTRUCTION INDUSTRY Abs: BIOSIS COPYRIGHT: BIOL ABS. RRM LITERATURE REVIEW HUMAN LUNG CANCER PLEURAL FIBROSIS OCCUPATIONAL ASTHMA RESPIRATORY INFECTIONS RESPIRATORY DISTRESS SYNDROME MORBIDITY CHEMICALS
1231208,Maguire et al. 1995,Reduction of the efficiency of extraction of lipophilic chemicals from water by dissolved organic matter,"BIOSIS COPYRIGHT: BIOL ABS. A study was made of the efficiency of liquid-liquid extraction of eight chlorinated hydrocarbons of varying lipophilicity from filtered (1 muM) organic-free water, soil humic acid solution, lacustrine dissolved organic matter solution, and a natural water. The efficiency of hexane extraction of the spiked chemicals without pH adjustment (i.e., the conventional technique) was reduced with increasing concentration of dissolved organic matter (DOM) and increasing chemical lipophilicity. At the same time, increasing amounts of the more lipophilic chemicals were found in subsequent extracts of the water at pH 12, and after chromic acid oxidation of the DOM. The results indicated that conventional liquid-liquid extraction underestimates the concentrations of ""dissolved"" highly lipophilic chemicals in fresh water, the extent of the underestimation depending upon the nature of the DOM. Sixteen-day exposure experiments with filtered natural waters containing roughly 5 mg DOM ind","Reduction of the efficiency of extraction of lipophilic chemicals from water by dissolved organic matter Abs: BIOSIS COPYRIGHT: BIOL ABS. A study was made of the efficiency of liquid-liquid extraction of eight chlorinated hydrocarbons of varying lipophilicity from filtered (1 muM) organic-free water, soil humic acid solution, lacustrine dissolved organic matter solution, and a natural water. The efficiency of hexane extraction of the spiked chemicals without pH adjustment (i.e., the conventional technique) was reduced with increasing concentration of dissolved organic matter (DOM) and increasing chemical lipophilicity. At the same time, increasing amounts of the more lipophilic chemicals were found in subsequent extracts of the water at pH 12, and after chromic acid oxidation of the DOM. The results indicated that conventional liquid-liquid extraction underestimates the concentrations of ""dissolved"" highly lipophilic chemicals in fresh water, the extent of the underestimation depending upon the nature of the DOM. Sixteen-day exposure experiments with filtered natural waters containing roughly 5 mg DOM ind"
1231205,Ringo 1993,"The effect of chromic acid (Cr2O3) on aerobic populations associated with the intestinal epithelial mucosa of Arctic charr, Salvelinus alpinus (L.)","BIOSIS COPYRIGHT: BIOL ABS. Populations of aerobic heterotrophic bacteria present in the gastrointestinal tract of healthy Arctic charr, Salvelinus alpinus (L.), were estimated using the dilution plate technique. The gastrointestinal bacterial flora of fish fed an unsupplemented diet was dominated by Gram-negative bacteria of the genera Acinetobacter, Aeromonas, Agrobacterium, Alcaligenes, Cytophaga, Flavobacterium, Pseudomonas, and Vibrio, and Gram-positive bacteria of the genera Arthrobacter, Brevibacterium, Corynebacterium, Kurthia, Lactobacillus, Microbacterium, Micrococcus, Staphylococcus, and Streptococcus. The composition of the indigenous aerobic bacterial flora in the digestive tract, and especially the microorganisms isolated from the midgut and hindgut regions, was affected by inclusion of 1% chromic oxide (Cr2O3) in the diet. Many of the Gram-negative bacterial genera and some of the Gram-positive bacterial genera were not detectable in the Cr2O3-fed fish. The midgut and hindgut regio","The effect of chromic acid (Cr2O3) on aerobic populations associated with the intestinal epithelial mucosa of Arctic charr, Salvelinus alpinus (L.) Abs: BIOSIS COPYRIGHT: BIOL ABS. Populations of aerobic heterotrophic bacteria present in the gastrointestinal tract of healthy Arctic charr, Salvelinus alpinus (L.), were estimated using the dilution plate technique. The gastrointestinal bacterial flora of fish fed an unsupplemented diet was dominated by Gram-negative bacteria of the genera Acinetobacter, Aeromonas, Agrobacterium, Alcaligenes, Cytophaga, Flavobacterium, Pseudomonas, and Vibrio, and Gram-positive bacteria of the genera Arthrobacter, Brevibacterium, Corynebacterium, Kurthia, Lactobacillus, Microbacterium, Micrococcus, Staphylococcus, and Streptococcus. The composition of the indigenous aerobic bacterial flora in the digestive tract, and especially the microorganisms isolated from the midgut and hindgut regions, was affected by inclusion of 1% chromic oxide (Cr2O3) in the diet. Many of the Gram-negative bacterial genera and some of the Gram-positive bacterial genera were not detectable in the Cr2O3-fed fish. The midgut and hindgut regio"
1231203,Pegnam and  Pilat 1992,Airborne particulate emissions from a chromic acid anodizing process tank,"Particulate mass concentration, particle size distribution, and particle chemical composition measurements have been conducted on the gases exhausting from a chromic acid anodizing process tank. Particle mass concentrations in the 200 to 20,000 mug/m3 range were measured using open-faced filters (47 mm diameter) adjacent to the process tank liquid and with closed filters (90 mm diameter) in the exhaust duct. Particle size distributions, measured using University of Washington Mark 3 and Mark 20 Cascade impactors, showed the particle aerodynamic mass median diameter was about 3 microns. Chemical analysis of the particle samples obtained by the Modified EPA Method 5 sampling train, the Mark 20 UW Cascade Impactors, and by the 47 mm and 90 mm diameter filters showed Cr+6 concentrations in the 20 to 1,500 mug/m3 range with over 99 percent of the chromium in particles larger than 1.0 microns diameter. An integrating nephelometer was used to measure the light scattering coefficient of the exhaust gases upstream of the wet scrubber. The light scattering coefficient increased by a factor of about 2-3 over the background level during the 40 minute time period while a part was being anodized. The bscat values ranged from 3 x 1O~5 to 3 x 10~4 meters""1 for the aerosol particles less than about 6 microns aerodynamic diameter.","Airborne particulate emissions from a chromic acid anodizing process tank Abs: Particulate mass concentration, particle size distribution, and particle chemical composition measurements have been conducted on the gases exhausting from a chromic acid anodizing process tank. Particle mass concentrations in the 200 to 20,000 mug/m3 range were measured using open-faced filters (47 mm diameter) adjacent to the process tank liquid and with closed filters (90 mm diameter) in the exhaust duct. Particle size distributions, measured using University of Washington Mark 3 and Mark 20 Cascade impactors, showed the particle aerodynamic mass median diameter was about 3 microns. Chemical analysis of the particle samples obtained by the Modified EPA Method 5 sampling train, the Mark 20 UW Cascade Impactors, and by the 47 mm and 90 mm diameter filters showed Cr+6 concentrations in the 20 to 1,500 mug/m3 range with over 99 percent of the chromium in particles larger than 1.0 microns diameter. An integrating nephelometer was used to measure the light scattering coefficient of the exhaust gases upstream of the wet scrubber. The light scattering coefficient increased by a factor of about 2-3 over the background level during the 40 minute time period while a part was being anodized. The bscat values ranged from 3 x 1O~5 to 3 x 10~4 meters""1 for the aerosol particles less than about 6 microns aerodynamic diameter."
1231202,Meister and  Ogle 1992,A WASTE DISPOSAL PROGRAM FOR A UNIVERSITY ART DEPARTMENT,BIOSIS COPYRIGHT: BIOL ABS. RRM HUMAN MUTAGENS CARCINOGENS TERATOGENS CHROMIC ACID SILICA COPPER ACETATE NICKEL,A WASTE DISPOSAL PROGRAM FOR A UNIVERSITY ART DEPARTMENT Abs: BIOSIS COPYRIGHT: BIOL ABS. RRM HUMAN MUTAGENS CARCINOGENS TERATOGENS CHROMIC ACID SILICA COPPER ACETATE NICKEL
1231201,Dinman 1991,THE MODE OF ABSORPTION DISTRIBUTION AND ELIMINATION OF TOXIC MATERIALS,BIOSIS COPYRIGHT: BIOL ABS. RRM HUMAN INDUSTRIAL TOXICOLOGY MATHEMATICAL MODEL,THE MODE OF ABSORPTION DISTRIBUTION AND ELIMINATION OF TOXIC MATERIALS Abs: BIOSIS COPYRIGHT: BIOL ABS. RRM HUMAN INDUSTRIAL TOXICOLOGY MATHEMATICAL MODEL
1231200,Doshi et al. 1991,Iodine-129 in soil and grass samples around a nuclear reprocessing plant,"BIOSIS COPYRIGHT: BIOL ABS. Neutron activation analysis was used to determine 129I in soil and grass samples around a reprocessing plant. The method involved wet oxidation of samples, using chromic acid, followed by distillation, collection of iodine in alkaline solution, loading on Dowex-1, irradiation and post-irradiation purification steps. The gamma-activity of 130I isotope of the purified samples was measured for quantitative determination of 129I. The experimental results showed that 129I and the 129I/127I atomic ratio in soil samples varied from 1.09 10-4 to 5.33spectively. Further, the geometric mean of soil-to-plant transfer factor (Bv) for 129I was found to be 0.16 which was comparable with other published values.","Iodine-129 in soil and grass samples around a nuclear reprocessing plant Abs: BIOSIS COPYRIGHT: BIOL ABS. Neutron activation analysis was used to determine 129I in soil and grass samples around a reprocessing plant. The method involved wet oxidation of samples, using chromic acid, followed by distillation, collection of iodine in alkaline solution, loading on Dowex-1, irradiation and post-irradiation purification steps. The gamma-activity of 130I isotope of the purified samples was measured for quantitative determination of 129I. The experimental results showed that 129I and the 129I/127I atomic ratio in soil samples varied from 1.09 10-4 to 5.33spectively. Further, the geometric mean of soil-to-plant transfer factor (Bv) for 129I was found to be 0.16 which was comparable with other published values."
1231187,Donner et al. 1986,DIMERCAPTOPROPANESULFONIC-ACID IN THE TREATMENT OF ACUTE COPPER AND ACUTE CHROMIUM POISONING,BIOSIS COPYRIGHT: BIOL ABS. RRM ABSTRACT HUMAN ANTIDOTE-DRUG METABOLIC-DRUG COPPER SULFATE CHROMIC-ACID PHARMACODYNAMICS,DIMERCAPTOPROPANESULFONIC-ACID IN THE TREATMENT OF ACUTE COPPER AND ACUTE CHROMIUM POISONING Abs: BIOSIS COPYRIGHT: BIOL ABS. RRM ABSTRACT HUMAN ANTIDOTE-DRUG METABOLIC-DRUG COPPER SULFATE CHROMIC-ACID PHARMACODYNAMICS
1231182,Schreier et al. 1999,Total Organic Carbon as a screening method for petroleum hydrocarbons,"BIOSIS COPYRIGHT: BIOL ABS. Total Organic Carbon (TOC) was used to screen soil samples for petroleum hydrocarbon contamination at a former refinery in Ohio. TOC was measured in the field via wet oxidation using chromic acid and colorimetry. Selected samples were also analyzed for Total Petroleum Hydrocarbons (TPH). Comparison of TOC and TPH results demonstrated that for this site, TOC values greater than 30,000 mg/kg indicated TPH concentrations above the action level.","Total Organic Carbon as a screening method for petroleum hydrocarbons Abs: BIOSIS COPYRIGHT: BIOL ABS. Total Organic Carbon (TOC) was used to screen soil samples for petroleum hydrocarbon contamination at a former refinery in Ohio. TOC was measured in the field via wet oxidation using chromic acid and colorimetry. Selected samples were also analyzed for Total Petroleum Hydrocarbons (TPH). Comparison of TOC and TPH results demonstrated that for this site, TOC values greater than 30,000 mg/kg indicated TPH concentrations above the action level."
1231179,Culver 1911,Treatment of Epithelioma by Curetting Followed by Cauterization With Chromic Acid and Later by Exposure to X-Ray,,Treatment of Epithelioma by Curetting Followed by Cauterization With Chromic Acid and Later by Exposure to X-Ray Abs: 
1231173,Waters 1946,A study of the mechanism of oxidation with chromic acid,,A study of the mechanism of oxidation with chromic acid Abs: 
1231171,Silverman and  Ege 1947,A rapid method for the determination of chromic acid mist in air,A rapid method is described for the determination of chromic-acid (7738945) mist in air using a hand pump and papers impregnated with a stable s-diphenylcarbazide reagent. The filter papers are 99 percent efficient and can be analyzed on location by means of permanent standards. The impregnated filter papers are stable for long periods if kept free from light and air. The method is adapted to rapid analysis of plating room and other atmospheres for appraisal of health standards and ventilating equipment.,A rapid method for the determination of chromic acid mist in air Abs: A rapid method is described for the determination of chromic-acid (7738945) mist in air using a hand pump and papers impregnated with a stable s-diphenylcarbazide reagent. The filter papers are 99 percent efficient and can be analyzed on location by means of permanent standards. The impregnated filter papers are stable for long periods if kept free from light and air. The method is adapted to rapid analysis of plating room and other atmospheres for appraisal of health standards and ventilating equipment.
1231168,Hemingway et al. 1948,Determination of volatile reducing substances (alcohol or ether) in blood and gases using barium diphenylamine sulfonate as an indicator for chromic acid titration,,Determination of volatile reducing substances (alcohol or ether) in blood and gases using barium diphenylamine sulfonate as an indicator for chromic acid titration Abs: 
1231167,Slack and  Waters 1948,A study of the mechanism of oxidation with chromic acid,,A study of the mechanism of oxidation with chromic acid Abs: 
1231166,Cornforth and  Popjak 1949,Chromic acid oxidation of ethyl alcohol,,Chromic acid oxidation of ethyl alcohol Abs: 
1231165,Glickman and  Johannessen 1950,"The effect of a six percent solution of chromic acid on the gingiva of the albino rat: A correlated gross, biomicroscopic and histologic study",,"The effect of a six percent solution of chromic acid on the gingiva of the albino rat: A correlated gross, biomicroscopic and histologic study Abs: "
1231164,Meyers 1950,Acute pulmonary complications following inhalation of chromic acid mist: Preliminary observations of 2 patients who inhaled massive amounts of chromic acid,,Acute pulmonary complications following inhalation of chromic acid mist: Preliminary observations of 2 patients who inhaled massive amounts of chromic acid Abs: 
1231161,Hickinbottom and  Wood 1951,Course of the oxidation of olefins by chromic acid,,Course of the oxidation of olefins by chromic acid Abs: 
1231152,Ueo et al. 1963,Chromic acid oxidation of tazettine,,Chromic acid oxidation of tazettine Abs: 
1231150,Fristedt et al. 1965,SURVIVAL IN A CASE OF ACUTE ORAL CHROMIC ACID POISONING WITH ACUTE RENAL FAILURE TREATED BY HAEMODIALYSIS,,SURVIVAL IN A CASE OF ACUTE ORAL CHROMIC ACID POISONING WITH ACUTE RENAL FAILURE TREATED BY HAEMODIALYSIS Abs: 
1231148,Mccloskey 1965,VIRIDIN. II. OXIDATION BY CHROMIC ACID,,VIRIDIN. II. OXIDATION BY CHROMIC ACID Abs: 
1231147,Curtis 1965,The transformation and resolution of 8-aza steroids by fungi,"1. When (+/-)-8-aza-d-homo-oestrone 3-methyl ether was added to a culture of Aspergillus ochraceus, the laevo-rotatory enantiomer is reduced to a 17A alcohol. Thus (+/-)-8-aza-d-homo-oestrone 3-methyl ether has been resolved into both its components, the laevo-rotatory enantiomer being obtained by chromic acid oxidation of the alcohol, and the dextro-rotatory enantiomer as residual precursor from the fermentation. 2. Fungi have been found to demethylate the 3-methyl ethers of 8-aza steroids to the corresponding phenols. In particular, 8-aza-d-homo-oestrone 3-methyl ether was demethylated by Aspergillus flavus and 8-aza-d-homo-oestradiol 3-methyl ether by Cunninghamella blakesleeana.","The transformation and resolution of 8-aza steroids by fungi Abs: 1. When (+/-)-8-aza-d-homo-oestrone 3-methyl ether was added to a culture of Aspergillus ochraceus, the laevo-rotatory enantiomer is reduced to a 17A alcohol. Thus (+/-)-8-aza-d-homo-oestrone 3-methyl ether has been resolved into both its components, the laevo-rotatory enantiomer being obtained by chromic acid oxidation of the alcohol, and the dextro-rotatory enantiomer as residual precursor from the fermentation. 2. Fungi have been found to demethylate the 3-methyl ethers of 8-aza steroids to the corresponding phenols. In particular, 8-aza-d-homo-oestrone 3-methyl ether was demethylated by Aspergillus flavus and 8-aza-d-homo-oestradiol 3-methyl ether by Cunninghamella blakesleeana."
1231146,Samitz and  Katz 1965,Protection against inhalation of chromic acid mist. Use of filters impregnated with ascorbic acid,,Protection against inhalation of chromic acid mist. Use of filters impregnated with ascorbic acid Abs: 
1231145,Scott 1967,A method for the degradation of radioactive nicotinic acid,"A chemical degradation scheme is reported, which permits the measurement of the radioactivity of each carbon atom of nicotinic acid. Nicotinic acid is decarboxylated by heating with copper chromite to give carbon dioxide (C-7) and pyridine. The pyridine is converted into 4-nitropyridine 1-oxide, which is heated with aqueous calcium hypobromite to give tribromonitromethane. Combustion of the latter gives carbon dioxide derived from C-4 of the nicotinic acid. Nicotinic acid is also reduced to nipecotic acid, which is oxidized to succinic acid by acidic potassium permanganate. Stepwise degradation of the succinic acid by standard procedures gives two samples of carbon dioxide, which correspond to C-3, C-6 and C-4, C-5 of the nicotinic acid. Benzoylation of the nipecotic acid, followed by oxidation with permanganate at pH7, gives 5-amino-4-carboxyvaleric acid; this is converted into 2-methyleneglutaric acid by the action of nitrous acid. Hydrogenation of the 2-methyleneglutaric acid over rhodium in methanol gives 2-methylglutaric acid, which is oxidized with dilute chromic acid to acetic acid. Stepwise degradation of the acetic acid by standard procedures gives two samples of carbon dioxide, which correspond to C-2 and C-3 of the nicotinic acid. Thus the radioactivities of C-2, C-3, C-4 and C-7 are determined directly and those of C-5 and C-6 by difference. The method was shown to be isotopically valid for [2,3,7-(14)C]-, [4,6-(14)C(2)]- and [5-(14)C]-nicotinic acid.","A method for the degradation of radioactive nicotinic acid Abs: A chemical degradation scheme is reported, which permits the measurement of the radioactivity of each carbon atom of nicotinic acid. Nicotinic acid is decarboxylated by heating with copper chromite to give carbon dioxide (C-7) and pyridine. The pyridine is converted into 4-nitropyridine 1-oxide, which is heated with aqueous calcium hypobromite to give tribromonitromethane. Combustion of the latter gives carbon dioxide derived from C-4 of the nicotinic acid. Nicotinic acid is also reduced to nipecotic acid, which is oxidized to succinic acid by acidic potassium permanganate. Stepwise degradation of the succinic acid by standard procedures gives two samples of carbon dioxide, which correspond to C-3, C-6 and C-4, C-5 of the nicotinic acid. Benzoylation of the nipecotic acid, followed by oxidation with permanganate at pH7, gives 5-amino-4-carboxyvaleric acid; this is converted into 2-methyleneglutaric acid by the action of nitrous acid. Hydrogenation of the 2-methyleneglutaric acid over rhodium in methanol gives 2-methylglutaric acid, which is oxidized with dilute chromic acid to acetic acid. Stepwise degradation of the acetic acid by standard procedures gives two samples of carbon dioxide, which correspond to C-2 and C-3 of the nicotinic acid. Thus the radioactivities of C-2, C-3, C-4 and C-7 are determined directly and those of C-5 and C-6 by difference. The method was shown to be isotopically valid for [2,3,7-(14)C]-, [4,6-(14)C(2)]- and [5-(14)C]-nicotinic acid."
1231144,Sharawy and  Lobene 1967,"Local effect of five-percent chromic acid on the gingiva and teeth of mice, rats and hamsters",,"Local effect of five-percent chromic acid on the gingiva and teeth of mice, rats and hamsters Abs: "
1231140,Lillie and  Henderson 1968,A short chromic acid-hematoxylin stain for frozen sections of formol-fixed brain and spinal cord,,A short chromic acid-hematoxylin stain for frozen sections of formol-fixed brain and spinal cord Abs: 
1231139,Evrard and  Janssen 1968,Gas-liquid chromatographic determination of human fecal bile acids,"A method for the determination of total bile acids in human feces that is suitable for routine application is described and discussed. Bile acids are extracted from freeze-dried feces with acetic acid and toluene, in the presence of the internal standard 23-nordeoxycholic acid. After saponification of the extract, bile acids and the internal standard are methylated and converted by mild chromic acid oxidation into their ketonic derivatives. The resultant mixture of a few stable compounds can be separated and measured quantitatively by gas-liquid chromatography on a methylsiloxane polymer. A reference bile acid mixture including the internal standard is also taken through the entire procedure with each series of samples. It has been demonstrated that, in spite of the omission of the usual purification steps, the method is specific for bile acids.","Gas-liquid chromatographic determination of human fecal bile acids Abs: A method for the determination of total bile acids in human feces that is suitable for routine application is described and discussed. Bile acids are extracted from freeze-dried feces with acetic acid and toluene, in the presence of the internal standard 23-nordeoxycholic acid. After saponification of the extract, bile acids and the internal standard are methylated and converted by mild chromic acid oxidation into their ketonic derivatives. The resultant mixture of a few stable compounds can be separated and measured quantitatively by gas-liquid chromatography on a methylsiloxane polymer. A reference bile acid mixture including the internal standard is also taken through the entire procedure with each series of samples. It has been demonstrated that, in spite of the omission of the usual purification steps, the method is specific for bile acids."
1231138,Hradec and  Dolejs 1968,The chemical constitution of carcinolipin,"1. The neutral portion of the molecule of carcinolipin was found to be cholesterol by comparison of mixed melting points with cholesterol, its dibromide and its acetate. 2. The fatty acid present in carcinolipin was subjected to oxidative degradation by chromic acid and permanganate. Butan-2-one was the main neutral degradation product resulting from both these procedures. A mixture of dibasic acids was obtained after the oxidation with chromic acid. Permanganate oxidation yielded a complete homologous series of branched-chain C(5)-C(17) fatty acids. 3. The mass spectrum of the acid was characteristic for a saturated C(17) acid. The alcohol prepared by lithium aluminium hydride reduction of the original acid showed a mass spectrum typical for an anteiso compound. 4. Comparison of mixed melting points, gas-liquid-chromatographic behaviour and mass spectra of the fatty acid isolated from carcinolipin with an authentic sample of 14-methylhexadecanoic acid demonstrated the identity of these compounds. Cholesterol esters synthesized from authentic cholesterol and the fatty acid isolated from carcinolipin or synthetic 14-methylhexadecanoic acid showed an identical stimulating effect on the incorporation of labelled algal-protein hydrolysate into rat liver transfer RNA in vitro. 5. Mass spectra, results of oxidative degradations and comparisons with an authentic sample, as well as biological activity of the synthetic cholesterol 14-methylhexadecanoate, provided good evidence that carcinolipin is cholesterol (+)-14-methylhexadecanoate.","The chemical constitution of carcinolipin Abs: 1. The neutral portion of the molecule of carcinolipin was found to be cholesterol by comparison of mixed melting points with cholesterol, its dibromide and its acetate. 2. The fatty acid present in carcinolipin was subjected to oxidative degradation by chromic acid and permanganate. Butan-2-one was the main neutral degradation product resulting from both these procedures. A mixture of dibasic acids was obtained after the oxidation with chromic acid. Permanganate oxidation yielded a complete homologous series of branched-chain C(5)-C(17) fatty acids. 3. The mass spectrum of the acid was characteristic for a saturated C(17) acid. The alcohol prepared by lithium aluminium hydride reduction of the original acid showed a mass spectrum typical for an anteiso compound. 4. Comparison of mixed melting points, gas-liquid-chromatographic behaviour and mass spectra of the fatty acid isolated from carcinolipin with an authentic sample of 14-methylhexadecanoic acid demonstrated the identity of these compounds. Cholesterol esters synthesized from authentic cholesterol and the fatty acid isolated from carcinolipin or synthetic 14-methylhexadecanoic acid showed an identical stimulating effect on the incorporation of labelled algal-protein hydrolysate into rat liver transfer RNA in vitro. 5. Mass spectra, results of oxidative degradations and comparisons with an authentic sample, as well as biological activity of the synthetic cholesterol 14-methylhexadecanoate, provided good evidence that carcinolipin is cholesterol (+)-14-methylhexadecanoate."
1231137,Burlingame and  Simoneit 1968,Isoprenoid Fatty acids isolated from the kerogen matrix of the green river formation (eocene),"Demineralized oil shale was oxidized with chromic acid, and C(14) to C(22) isoprenoid fatty acids were isolated and identified. The major components of the branched-chain acid fraction after successive 3-, 6-, and 15-hour oxidations are C(15) and C(16) branched-chain acids; C(17), C(19) (norphytanic acid), and C(20) (phytanic acid) were obtained in lower concentration; no C(18) product was obtained. Separations were effected by column and gas-liquid chromatography, and the structures of individual components were determined by high- and low-resolution mass spectrometry.","Isoprenoid Fatty acids isolated from the kerogen matrix of the green river formation (eocene) Abs: Demineralized oil shale was oxidized with chromic acid, and C(14) to C(22) isoprenoid fatty acids were isolated and identified. The major components of the branched-chain acid fraction after successive 3-, 6-, and 15-hour oxidations are C(15) and C(16) branched-chain acids; C(17), C(19) (norphytanic acid), and C(20) (phytanic acid) were obtained in lower concentration; no C(18) product was obtained. Separations were effected by column and gas-liquid chromatography, and the structures of individual components were determined by high- and low-resolution mass spectrometry."
1231135,Tallent et al. 1968,Structure and intraglyceride distribution of coriolic acid,"Coriolic [(R)-13-hydroxy-cis-9,trans-11-octadecadienoic] acid (III, R=Z=H) was isolated as the methyl ester from twoCoriaria seed oils in 66 and 68% yields. The double bonds and hydroxyl group were located by periodate-permanganate oxidation before, and chromic acid oxidation after, hydrogenation of the double bonds. Alternatively the positions of the functional groups were indicated by a convenient micro-ozonolysis-gas-liquid chromatographic procedure. Determination of products from partial hydrolysis of theCoriaria oils with pancreatic lipase (EC 3.1.1.3) revealed a preference of the corioloyl group for the 1,3-positions in triglyceride molecules. The possible significance of coriolic acid as an intermediate in the biogenetic conversion of linoleic acid to conjugated trienoic acids is discussed.","Structure and intraglyceride distribution of coriolic acid Abs: Coriolic [(R)-13-hydroxy-cis-9,trans-11-octadecadienoic] acid (III, R=Z=H) was isolated as the methyl ester from twoCoriaria seed oils in 66 and 68% yields. The double bonds and hydroxyl group were located by periodate-permanganate oxidation before, and chromic acid oxidation after, hydrogenation of the double bonds. Alternatively the positions of the functional groups were indicated by a convenient micro-ozonolysis-gas-liquid chromatographic procedure. Determination of products from partial hydrolysis of theCoriaria oils with pancreatic lipase (EC 3.1.1.3) revealed a preference of the corioloyl group for the 1,3-positions in triglyceride molecules. The possible significance of coriolic acid as an intermediate in the biogenetic conversion of linoleic acid to conjugated trienoic acids is discussed."
1231133,Haslewood and  Tökés 1969,Comparative studies of bile salts. Bile salts of the lamprey Petromyzon marinus L,"1. Bile salts of Petromyzon marinus L. ammocoetes appeared to consist solely or chiefly of a crystalline substance, whose chromatographic and i.r.-spectral characteristics suggested that it was a monosulphate ester of a bile alcohol having the 3alpha,7alpha,12alpha-trihydroxy pattern of substitution in a 5alpha-steroid nucleus. 2. This substance on cleavage with dioxan-trichloroacetic acid gave petromyzonol, n.m.r. and mass-spectral examination of which suggested the structure 5alpha-cholane-3alpha,7alpha,12alpha,24-tetrol. 3. 3alpha,7alpha,12alpha-Trihydroxy-5alpha-cholanoic acid (allocholic acid) from the lizards Anolis lineatopus lineatopus Gray and Cyclura carinata Harlan (family Iguanidae) was esterified with propan-1-ol and reduced by lithium aluminium hydride to 5alpha-cholane-3alpha,7alpha,12alpha,24-tetrol, identical with petromyzonol. 4. Chromic acid oxidation of petromyzonol sulphate from lamprey bile, followed by acid hydrolysis, gave 24-hydroxy-5alpha-cholane-3,7,12-trione; hence the sulphate ester group is at C-24. 5. Petromyzonol sulphate is both primitive and unique: a study of its biogenesis might improve our understanding of evolution at the molecular level.","Comparative studies of bile salts. Bile salts of the lamprey Petromyzon marinus L Abs: 1. Bile salts of Petromyzon marinus L. ammocoetes appeared to consist solely or chiefly of a crystalline substance, whose chromatographic and i.r.-spectral characteristics suggested that it was a monosulphate ester of a bile alcohol having the 3alpha,7alpha,12alpha-trihydroxy pattern of substitution in a 5alpha-steroid nucleus. 2. This substance on cleavage with dioxan-trichloroacetic acid gave petromyzonol, n.m.r. and mass-spectral examination of which suggested the structure 5alpha-cholane-3alpha,7alpha,12alpha,24-tetrol. 3. 3alpha,7alpha,12alpha-Trihydroxy-5alpha-cholanoic acid (allocholic acid) from the lizards Anolis lineatopus lineatopus Gray and Cyclura carinata Harlan (family Iguanidae) was esterified with propan-1-ol and reduced by lithium aluminium hydride to 5alpha-cholane-3alpha,7alpha,12alpha,24-tetrol, identical with petromyzonol. 4. Chromic acid oxidation of petromyzonol sulphate from lamprey bile, followed by acid hydrolysis, gave 24-hydroxy-5alpha-cholane-3,7,12-trione; hence the sulphate ester group is at C-24. 5. Petromyzonol sulphate is both primitive and unique: a study of its biogenesis might improve our understanding of evolution at the molecular level."
1231131,Vessman and  Strömberg 1969,Determination of terodiline (Bicor) in serum by gas chromatography and electron capture detection of benzophenone formed by chromic acid oxidation,,Determination of terodiline (Bicor) in serum by gas chromatography and electron capture detection of benzophenone formed by chromic acid oxidation Abs: 
1231130,Johnson et al. 1969,Stereochemistry of microbiological hydroxylation. 3. Hydroxylation of 3-benzoyl-3-azabicyclo[3.3.1]nonane with Rhizopus arrhizus. Novel chromic acid oxidations of substrate and product,,Stereochemistry of microbiological hydroxylation. 3. Hydroxylation of 3-benzoyl-3-azabicyclo[3.3.1]nonane with Rhizopus arrhizus. Novel chromic acid oxidations of substrate and product Abs: 
1231129,Cherayil and  Scaria 1970,Thin-layer chromatography of tissue lipids without extraction,"Frozen tissue sections were applied directly to silica gel plates, and the lipids were separated by developing the plates in different solvent systems. Quantitation of the lipid classes was achieved by direct transmission densitometry after the plates were treated with a chromic acid-sulfuric acid spray.","Thin-layer chromatography of tissue lipids without extraction Abs: Frozen tissue sections were applied directly to silica gel plates, and the lipids were separated by developing the plates in different solvent systems. Quantitation of the lipid classes was achieved by direct transmission densitometry after the plates were treated with a chromic acid-sulfuric acid spray."
1231128,Vessman et al. 1970,"Gas chromatography and electron capture detection of benzophenone formed by chromic acid oxidation. 2. Determination of emepronium (Cetiprin), a quaternary ammonium compound in serum",,"Gas chromatography and electron capture detection of benzophenone formed by chromic acid oxidation. 2. Determination of emepronium (Cetiprin), a quaternary ammonium compound in serum Abs: "
1231127,Vessman et al. 1970,Gas chromatography and electron capture detection of benzophenone formed by chromic acid oxidation. 3. Applications in the determination of gem-diphenylsubstituted compounds,,Gas chromatography and electron capture detection of benzophenone formed by chromic acid oxidation. 3. Applications in the determination of gem-diphenylsubstituted compounds Abs: 
1231126,Vessman and  Hartvig 1971,Gas chromatography and electron capture detection of benzophenone formed by chromic acid oxidation. 4. Effects of ring substituents and chain length on benzophenone yield in some gem-diphenylsubstituted compounds,"IPA COPYRIGHT: ASHP The effects of ring substituents and chain length on benzophenone yield in 21 derivatives of diphenylalkanes, benzhydrol, diphenylpropylamine and 2-benzylpyridine were studied.","Gas chromatography and electron capture detection of benzophenone formed by chromic acid oxidation. 4. Effects of ring substituents and chain length on benzophenone yield in some gem-diphenylsubstituted compounds Abs: IPA COPYRIGHT: ASHP The effects of ring substituents and chain length on benzophenone yield in 21 derivatives of diphenylalkanes, benzhydrol, diphenylpropylamine and 2-benzylpyridine were studied."
1231125,Vessman and  Hartvig 1971,Gas chromatography and electron capture detection of benzophenone formed by chromic acid oxidation. 5. Formation rate of benzophenone in the chromic acid oxidation of some gem-diphenyl-substituted compounds,IPA COPYRIGHT: ASHP The rate of formation of benzophenone from diphenylmethane derivatives was studied. gem-Diphenylalkylamine derivatives with a piperazine ring linked to the alpha-carbon and o-chloro-substituted compounds were found to be oxidized very slowly. Increasing the chromium trioxide content in the reagent (chromium trioxide in glacial acetic acid containing 6% w/v of concentrated sulfuric acid) generally increased the rate of formation of benzophenone.,Gas chromatography and electron capture detection of benzophenone formed by chromic acid oxidation. 5. Formation rate of benzophenone in the chromic acid oxidation of some gem-diphenyl-substituted compounds Abs: IPA COPYRIGHT: ASHP The rate of formation of benzophenone from diphenylmethane derivatives was studied. gem-Diphenylalkylamine derivatives with a piperazine ring linked to the alpha-carbon and o-chloro-substituted compounds were found to be oxidized very slowly. Increasing the chromium trioxide content in the reagent (chromium trioxide in glacial acetic acid containing 6% w/v of concentrated sulfuric acid) generally increased the rate of formation of benzophenone.
1231121,Hodges et al. 1972,Purification of an ion-stimulated adenosine triphosphatase from plant roots: association with plasma membranes,"A membrane-bound adenosine triphosphatase (EC 3.6.1.3) that requires Mg(++) and that is stimulated by monovalent ions has been purified 7- to 8-fold from homogenates of oat (Avena sativa L. Cult. Goodfield) roots by discontinuous sucrose-gradient centrifugation. The enzyme was substrate specific; adenosine triphosphate was hydrolyzed 25 times more rapidly than other nucleoside triphosphates. The membrane fraction containing adenosine triphosphatase was enriched in plasma membranes, which were identified by the presence of a glucan synthetase (EC 2.4.1.12), a high sterol to phospholipid ratio, and by a stain consisting of periodic acid, chromic acid, and phosphotungstic acid that is specific for plant plasma membranes. Oat-root plasma membranes and the associated adenosine triphosphatase were purified on either a 6-layer discontinuous sucrose gradient or on a simplified gradient consisting of only two sucrose layers.These results represent the first demonstration that plant plasma membranes contain an adenosine triphosphatase that is activated by monovalent ions, and this finding further implicates the enzyme in the absorption of inorganic ions by plant roots.","Purification of an ion-stimulated adenosine triphosphatase from plant roots: association with plasma membranes Abs: A membrane-bound adenosine triphosphatase (EC 3.6.1.3) that requires Mg(++) and that is stimulated by monovalent ions has been purified 7- to 8-fold from homogenates of oat (Avena sativa L. Cult. Goodfield) roots by discontinuous sucrose-gradient centrifugation. The enzyme was substrate specific; adenosine triphosphate was hydrolyzed 25 times more rapidly than other nucleoside triphosphates. The membrane fraction containing adenosine triphosphatase was enriched in plasma membranes, which were identified by the presence of a glucan synthetase (EC 2.4.1.12), a high sterol to phospholipid ratio, and by a stain consisting of periodic acid, chromic acid, and phosphotungstic acid that is specific for plant plasma membranes. Oat-root plasma membranes and the associated adenosine triphosphatase were purified on either a 6-layer discontinuous sucrose gradient or on a simplified gradient consisting of only two sucrose layers.These results represent the first demonstration that plant plasma membranes contain an adenosine triphosphatase that is activated by monovalent ions, and this finding further implicates the enzyme in the absorption of inorganic ions by plant roots."
1231120,Utidjian 1973,Criteria for a recommended standard--occupational exposure to chromic acid,,Criteria for a recommended standard--occupational exposure to chromic acid Abs: 
1231119,Cooper 1973,Commentary: The criteria document for chromic acid,,Commentary: The criteria document for chromic acid Abs: 
1231118,Hartvig 1974,Gas chromatography and electron capture detection of benzophenone. IX. Identification of the chromic acid oxidation product of pipradrol,"The chromic acid oxidation product of pipradrol is identified as 6-benzoyl-1,2,3,4-tetrahydropyridine. The high electron capture response is shown to be due to an intramolecular hydrogen bonding which increases the stabilization of a captured electron.","Gas chromatography and electron capture detection of benzophenone. IX. Identification of the chromic acid oxidation product of pipradrol Abs: The chromic acid oxidation product of pipradrol is identified as 6-benzoyl-1,2,3,4-tetrahydropyridine. The high electron capture response is shown to be due to an intramolecular hydrogen bonding which increases the stabilization of a captured electron."
1231116,Dutt 1975,Feulgen staining of mammalian tissues fixed in picro-formol-acetic acid,"The paper describes a highly satisfactory method for in situ localization of DNA in tissues fixed in picro-formol-acetic acid or picro-formol-acetic-chromic acid mixtures following a technique in the Feulgen procedure as devised by the author. Mammalian tissues fixed in these fixatives can be hydrolysed in 6N HCl at 35 degrees C for 10 min, rinsed in water, stained with Schiff reagent after exposing the sections under UV light for 10 min, washed in water, dehydrated through a graduated series of ethanol, cleared in xylol and mounted in DPX. Sections of tissues fixed in picro-formol-acetic-chromic acid mixtures after acid hydrolysis when stained with an aqueous solution of basic fuchsin are also found to be very satisfactory for in situ localization of DNA.","Feulgen staining of mammalian tissues fixed in picro-formol-acetic acid Abs: The paper describes a highly satisfactory method for in situ localization of DNA in tissues fixed in picro-formol-acetic acid or picro-formol-acetic-chromic acid mixtures following a technique in the Feulgen procedure as devised by the author. Mammalian tissues fixed in these fixatives can be hydrolysed in 6N HCl at 35 degrees C for 10 min, rinsed in water, stained with Schiff reagent after exposing the sections under UV light for 10 min, washed in water, dehydrated through a graduated series of ethanol, cleared in xylol and mounted in DPX. Sections of tissues fixed in picro-formol-acetic-chromic acid mixtures after acid hydrolysis when stained with an aqueous solution of basic fuchsin are also found to be very satisfactory for in situ localization of DNA."
1231115,St Clair et al. 1975,"Evaluation of chromic oxide, glycerol triether, and beta-sitosterol as fecal flow markers in two species of nonhuman primates","Recovery of beta-sitosterol, glycerol triether (1-hexadecyl-2,3-didodecyl glycerol triether), and chromic oxide was studied in African green monkeys and stumptail macaques consuming diets containing 0.75 mg/Cal cholesterol and 38% of calories as safflower oil or butter. Following oral administration of these compounds, feces were collected daily for 9 days. For all animals, excretion of beta-sitosterol and glycerol triether paralleled one another almost exactly. Except for two animals, this was also true for chromic acid. Essentially 100% of the administered beta-sitosterol and 90-95% of the glycerol triether were recovered; excretion of these markers virtually was complete by day 3. Ninety-two percent of the beta-sitosterol was isolated in the nonsaponifiable lipid extract of the feces with less than 6% in the remaining aqueous phase. A maximum of 3.1% of the beta-sitosterol and 1.8% of the glycerol triether were found in the blood. For stumptail macaques, the major excretory form of beta-sitosterol was the 5 beta-derivative. African green monkeys were more variable; one animal excreted the bulk of the beta-sitosterol unchanged while others excreted greater than 80% as the ring-saturated 5 beta-derivative. Animals consuming the safflower oil containing diet consistently excreted a greater percentage of the beta-sitosterol unchanged, compared with those animals eating the butter containing diet. There was no evidence for steroid ring degradation in any of the animals used in this study.","Evaluation of chromic oxide, glycerol triether, and beta-sitosterol as fecal flow markers in two species of nonhuman primates Abs: Recovery of beta-sitosterol, glycerol triether (1-hexadecyl-2,3-didodecyl glycerol triether), and chromic oxide was studied in African green monkeys and stumptail macaques consuming diets containing 0.75 mg/Cal cholesterol and 38% of calories as safflower oil or butter. Following oral administration of these compounds, feces were collected daily for 9 days. For all animals, excretion of beta-sitosterol and glycerol triether paralleled one another almost exactly. Except for two animals, this was also true for chromic acid. Essentially 100% of the administered beta-sitosterol and 90-95% of the glycerol triether were recovered; excretion of these markers virtually was complete by day 3. Ninety-two percent of the beta-sitosterol was isolated in the nonsaponifiable lipid extract of the feces with less than 6% in the remaining aqueous phase. A maximum of 3.1% of the beta-sitosterol and 1.8% of the glycerol triether were found in the blood. For stumptail macaques, the major excretory form of beta-sitosterol was the 5 beta-derivative. African green monkeys were more variable; one animal excreted the bulk of the beta-sitosterol unchanged while others excreted greater than 80% as the ring-saturated 5 beta-derivative. Animals consuming the safflower oil containing diet consistently excreted a greater percentage of the beta-sitosterol unchanged, compared with those animals eating the butter containing diet. There was no evidence for steroid ring degradation in any of the animals used in this study."
1231113,Royle 1975,Toxicity of chromic acid in the chromium plating industry(2),"A population of chromium platers in the West Riding of Yorkshire, England, together with a closely matched control group of manual workers in the same area, were subjected to morbidity screening for respiratory symptoms; the plater population was also screened for the ulcerative and dermatitic lesions commonly seen in chromate handlers. A standard questionnaire was used, but no physical examinations or physiological tests were performed; questionnaires relating to 997 platers and 1117 controls were successfully completed. In general, respiratory symptoms were experienced to a greater extent by the plater population. A higher proportion of platers had worked in dusty jobs; when the populations were divided into dust-exposed and not-dust-exposed groups, the disparity in symptomatology was more marked in the group of dust-exposed subjects. An exception appeared in the case of effort dyspnea which, in its most severe form, affected practically the same proportion of each population. The prevalence of bronchial asthma was high in both platers (13.1%) and controls (9.8%), this increase being much more marked in the dust-exposed group. In the case of seasonal hay fever, 3.9% of platers and 5.5% of controls were affected. The risk of skin and intranasal ulceration increases, progressively, the longer the period of chromic acid exposure, whereas allergic contact dermatitis occurs equally in platers with short and longer exposure. An industrial hygiene survey, including air and dust analyses for chromic acid content, was carried out in 42 of the 54 plating plants from which the plater population was derived. In only 2 cases was the threshold limit value (TLV) for atmospheric chromic acid exceeded. Analyses of many dust scrapings showed chromic acid content of from 0-298 mg/g. No comparison figures are available, but it is thought that these are high, and that the dislodgement of such dust could form an intermittent inhalant hazard in chromium plating.","Toxicity of chromic acid in the chromium plating industry(2) Abs: A population of chromium platers in the West Riding of Yorkshire, England, together with a closely matched control group of manual workers in the same area, were subjected to morbidity screening for respiratory symptoms; the plater population was also screened for the ulcerative and dermatitic lesions commonly seen in chromate handlers. A standard questionnaire was used, but no physical examinations or physiological tests were performed; questionnaires relating to 997 platers and 1117 controls were successfully completed. In general, respiratory symptoms were experienced to a greater extent by the plater population. A higher proportion of platers had worked in dusty jobs; when the populations were divided into dust-exposed and not-dust-exposed groups, the disparity in symptomatology was more marked in the group of dust-exposed subjects. An exception appeared in the case of effort dyspnea which, in its most severe form, affected practically the same proportion of each population. The prevalence of bronchial asthma was high in both platers (13.1%) and controls (9.8%), this increase being much more marked in the dust-exposed group. In the case of seasonal hay fever, 3.9% of platers and 5.5% of controls were affected. The risk of skin and intranasal ulceration increases, progressively, the longer the period of chromic acid exposure, whereas allergic contact dermatitis occurs equally in platers with short and longer exposure. An industrial hygiene survey, including air and dust analyses for chromic acid content, was carried out in 42 of the 54 plating plants from which the plater population was derived. In only 2 cases was the threshold limit value (TLV) for atmospheric chromic acid exceeded. Analyses of many dust scrapings showed chromic acid content of from 0-298 mg/g. No comparison figures are available, but it is thought that these are high, and that the dislodgement of such dust could form an intermittent inhalant hazard in chromium plating."
1231112,Royle 1975,Toxicity of chromic acid in the chromium plating industry (1),"Commercial chromium plating has been an expanding industry in Great Britain since 1925. The annual numbers of cases of skin and nasal mucosal ulceration due to the effects of chrome contact, reported under the 1919 Regulations, show that Cr platers are affected in this way at least as frequently as chrome handlers in, e.g., the chrome-chemical and chrome-pigment industries. There is an increased risk of cancer, especially in the form of broncho-pulmonary carcinoma, among workers in these latter industries, but hitherto no evidence has been sought to discover whether a comparable situation is present in the Cr plating industry. A retrospective mortality study among Cr platers in the West Riding of Yorkshire (England) was carried out between Feb. 1969 and May 1972, and a prospective study was initiated on the latter date. Concurrently, a matched control population, consisting of manual workers with no occupational chrome contact, was defined and subjected to the same trace and interview and mortality search techniques. For the mortality survey, 1238 Cr platers and 1284 controls were available for study. Prior to May 1972, 109 (8.80%) deaths were found among the plater population, compared with 85 (6.62) among controls. Most of this increase in plater deaths was attributable to malignant neoplastic disease, which was certified as the cause of death in 39 (3.15%) platers and 21 (1.64%) controls (5.0% significant). The increase in cancer deaths among the platers was not confined to broncho-pulmonary cancer (17 platers, 10 controls), but showed itself to a similar extent in cancers at other sites (22 platers, 11 controls). Deaths due to non-neoplastic primary respiratory disease were slightly more numerous among platers (18 platers, 13 controls), but cardiovascular deaths and those with other causes were almost identical (52 platers, 51 controls). Further information will be furnished by the prospective mortality study, which, in its 1st 2 yr, has shown a similar trend in the distribution of certified causes of death.","Toxicity of chromic acid in the chromium plating industry (1) Abs: Commercial chromium plating has been an expanding industry in Great Britain since 1925. The annual numbers of cases of skin and nasal mucosal ulceration due to the effects of chrome contact, reported under the 1919 Regulations, show that Cr platers are affected in this way at least as frequently as chrome handlers in, e.g., the chrome-chemical and chrome-pigment industries. There is an increased risk of cancer, especially in the form of broncho-pulmonary carcinoma, among workers in these latter industries, but hitherto no evidence has been sought to discover whether a comparable situation is present in the Cr plating industry. A retrospective mortality study among Cr platers in the West Riding of Yorkshire (England) was carried out between Feb. 1969 and May 1972, and a prospective study was initiated on the latter date. Concurrently, a matched control population, consisting of manual workers with no occupational chrome contact, was defined and subjected to the same trace and interview and mortality search techniques. For the mortality survey, 1238 Cr platers and 1284 controls were available for study. Prior to May 1972, 109 (8.80%) deaths were found among the plater population, compared with 85 (6.62) among controls. Most of this increase in plater deaths was attributable to malignant neoplastic disease, which was certified as the cause of death in 39 (3.15%) platers and 21 (1.64%) controls (5.0% significant). The increase in cancer deaths among the platers was not confined to broncho-pulmonary cancer (17 platers, 10 controls), but showed itself to a similar extent in cancers at other sites (22 platers, 11 controls). Deaths due to non-neoplastic primary respiratory disease were slightly more numerous among platers (18 platers, 13 controls), but cardiovascular deaths and those with other causes were almost identical (52 platers, 51 controls). Further information will be furnished by the prospective mortality study, which, in its 1st 2 yr, has shown a similar trend in the distribution of certified causes of death."
1231111,Bowen et al. 1975,The distribution of oxidizable mucosubstances and polysaccharides in the planarian Polycelis tenuis Iijima,"A chromic acid oxidation-silver technique was used to localize polysaccharide material in Polycelis tenuis at the electron microscope level. In the epithelium, staining was observed within apical vacuoles and on the free surfaces of the cells. A similar staining was observed in relation to the glycocalyx of the pharyngeal epithelia and that of the flame cells. Silver was deposited in the basement membrane. In the parenchyma, the major components giving a positive reaction were the cyanophil and mucous gland cells. Particularly strong silver staining (confirmed by X-ray microanalysis) was observed in the granules and Golgi apparatus of the cyanophil cells. IDPase activity was also found in relation to the Golgi apparatus and its secretory products. The overall distribution of mucopolysaccharide material was confirmed with the PAS and Alcian blue techniques. The fine structural localization of the Alcian blue was also determined using electron microscopy and X-ray microanalysis.","The distribution of oxidizable mucosubstances and polysaccharides in the planarian Polycelis tenuis Iijima Abs: A chromic acid oxidation-silver technique was used to localize polysaccharide material in Polycelis tenuis at the electron microscope level. In the epithelium, staining was observed within apical vacuoles and on the free surfaces of the cells. A similar staining was observed in relation to the glycocalyx of the pharyngeal epithelia and that of the flame cells. Silver was deposited in the basement membrane. In the parenchyma, the major components giving a positive reaction were the cyanophil and mucous gland cells. Particularly strong silver staining (confirmed by X-ray microanalysis) was observed in the granules and Golgi apparatus of the cyanophil cells. IDPase activity was also found in relation to the Golgi apparatus and its secretory products. The overall distribution of mucopolysaccharide material was confirmed with the PAS and Alcian blue techniques. The fine structural localization of the Alcian blue was also determined using electron microscopy and X-ray microanalysis."
1231110,Pollow et al. 1975,Progesterone metabolism in normal human endometrium during the menstrual cycle and in endometrial carcinoma,"Different subcellular fractions (purity checked by electron microscopy and respective marker enzymes) were incubated with 0.1 muCi 14C-progesterone (10 muM) in 0.15 M phosphate buffer at pH 7.4 and 37 C under air for varying periods of time in the presence of NAD(P)H (500 muM). By the preparation of chromic acid oxidation products and acetates, thin-layer chromatography, and crystallisation to constant specific activity, the following metabolites were identified: 20alpha-hydroxypregn-4-en-3-one, 20alpha-hydroxy-5alpha-pregnan-3-one, 20alpha-hydroxy-5beta-pregnan-3-one, 5alpha-pregnane-3,20-dione, and 5beta-pregnane-3,20-dione, indicating the presence of a 20alpha-hydroxysteroid dehydrogenase (20alpha-HSD) and 5alpha- and 5beta-reductases. Most of the 20alpha-HSD activity was located in mitochondria (associated mainly with outer membranes) and microsomes. Purified nuclei and cytosol contained 1/6 to 1/18 of the activity of mitochondria and microsomes, respectively. SUBFRACTIONS OF ENDOMETRIAL CELLS ONLY CONTAINED EITHER 5ALPHA- OR 5BETA-REDUCTASE ACTIVITY. 5alpha-reductase activity was mainly associated with microsomes, 5beta-reductase activity was found only in the cytosol. While in normal endometrium specific enzyme activities in subcellular fractions depended on the phase of the cycle, in endometrial carcinoma it depended on the degree of tumour differentiation. The highest values of 5alpha-reductase activity were found in the early proliferative phase. 20alpha-HSD activity was highest in the middle of the secretory phase. The specific activity of the 5alpha-reductase increased with decreasing differentiation of the tumour while the specific activity of the 20alpha-HSD decreased. Kinetic parameters (Km-values, coenzyme requirements and maximum velocities) were determined. The Km-value for progesterone of the 20alpha-HSD in proliferative endometrium was significantly higher than in secretory endometrium, while the Km-values of the 5alpha- and 5beta-reductases were considerably lower during the proliferative than secretory phase.","Progesterone metabolism in normal human endometrium during the menstrual cycle and in endometrial carcinoma Abs: Different subcellular fractions (purity checked by electron microscopy and respective marker enzymes) were incubated with 0.1 muCi 14C-progesterone (10 muM) in 0.15 M phosphate buffer at pH 7.4 and 37 C under air for varying periods of time in the presence of NAD(P)H (500 muM). By the preparation of chromic acid oxidation products and acetates, thin-layer chromatography, and crystallisation to constant specific activity, the following metabolites were identified: 20alpha-hydroxypregn-4-en-3-one, 20alpha-hydroxy-5alpha-pregnan-3-one, 20alpha-hydroxy-5beta-pregnan-3-one, 5alpha-pregnane-3,20-dione, and 5beta-pregnane-3,20-dione, indicating the presence of a 20alpha-hydroxysteroid dehydrogenase (20alpha-HSD) and 5alpha- and 5beta-reductases. Most of the 20alpha-HSD activity was located in mitochondria (associated mainly with outer membranes) and microsomes. Purified nuclei and cytosol contained 1/6 to 1/18 of the activity of mitochondria and microsomes, respectively. SUBFRACTIONS OF ENDOMETRIAL CELLS ONLY CONTAINED EITHER 5ALPHA- OR 5BETA-REDUCTASE ACTIVITY. 5alpha-reductase activity was mainly associated with microsomes, 5beta-reductase activity was found only in the cytosol. While in normal endometrium specific enzyme activities in subcellular fractions depended on the phase of the cycle, in endometrial carcinoma it depended on the degree of tumour differentiation. The highest values of 5alpha-reductase activity were found in the early proliferative phase. 20alpha-HSD activity was highest in the middle of the secretory phase. The specific activity of the 5alpha-reductase increased with decreasing differentiation of the tumour while the specific activity of the 20alpha-HSD decreased. Kinetic parameters (Km-values, coenzyme requirements and maximum velocities) were determined. The Km-value for progesterone of the 20alpha-HSD in proliferative endometrium was significantly higher than in secretory endometrium, while the Km-values of the 5alpha- and 5beta-reductases were considerably lower during the proliferative than secretory phase."
1231109,Taylor 1975,Sudden deafness following chromic acid application to a perforation of the tympanic membrane,"It is current practice in the treatment of many ear diseases to instil locally into the ear potentially ototoxic agents. It is now becoming increasingly clear that some of these agents may pass from the middle to the inner ear despite the presence of intact labyrinthine windows and hence produce deafness. This paper reports a case of severe sensorineural deafness which developed following the application of chromic acid to a perforation of the tympanic membrane--a hitherto unrecognized complication. Therefore, the risks outlined above should be carefully considered prior to local therapy with any such agents and they should be applied with extreme caution.","Sudden deafness following chromic acid application to a perforation of the tympanic membrane Abs: It is current practice in the treatment of many ear diseases to instil locally into the ear potentially ototoxic agents. It is now becoming increasingly clear that some of these agents may pass from the middle to the inner ear despite the presence of intact labyrinthine windows and hence produce deafness. This paper reports a case of severe sensorineural deafness which developed following the application of chromic acid to a perforation of the tympanic membrane--a hitherto unrecognized complication. Therefore, the risks outlined above should be carefully considered prior to local therapy with any such agents and they should be applied with extreme caution."
1231107,Baier et al. 1975,Thromboresistance of glass after glow discharge treatment in argon,"Glow discharge treated (GDT) inorganic materials are sterile and free of all organic contaminants. Such materials implanted in the canine inferior vena cava often demonstrate significant thromboresistance. Standard Pyrex glass tubing was GDT in argon to provide a surface free energy above 70 dynes/cm, slight surface negativity, and other surface-physical modifications of its interface. Chromic acid cleaned lengths of the same tubing, and short segments whose edges were not fire-polished were used as controls. Upon canine implantation, the in vivo results were similar in independent surgical laboratories. The glass was implanted as 1.4 cm long rings or as 5 cm long tubes in separate medical centers according to different protocols. GDT specimens remained patent; all controls accumulated thrombi. A remarkably pure, low critical surface tension, labile protein coating covered all cylindrical lumens after 2 hr in vivo. This coating diminished within 2 weeks and was essentially absent after 480 days, eeven though scanning EM showed evidence of a micron thick luminal film, probably eroding glass. No emboli were found in the implant animal's kidney or lungs at any stage.","Thromboresistance of glass after glow discharge treatment in argon Abs: Glow discharge treated (GDT) inorganic materials are sterile and free of all organic contaminants. Such materials implanted in the canine inferior vena cava often demonstrate significant thromboresistance. Standard Pyrex glass tubing was GDT in argon to provide a surface free energy above 70 dynes/cm, slight surface negativity, and other surface-physical modifications of its interface. Chromic acid cleaned lengths of the same tubing, and short segments whose edges were not fire-polished were used as controls. Upon canine implantation, the in vivo results were similar in independent surgical laboratories. The glass was implanted as 1.4 cm long rings or as 5 cm long tubes in separate medical centers according to different protocols. GDT specimens remained patent; all controls accumulated thrombi. A remarkably pure, low critical surface tension, labile protein coating covered all cylindrical lumens after 2 hr in vivo. This coating diminished within 2 weeks and was essentially absent after 480 days, eeven though scanning EM showed evidence of a micron thick luminal film, probably eroding glass. No emboli were found in the implant animal's kidney or lungs at any stage."
1231105,Warchol et al. 1976,Glycoproteins in membranes of secretory granules of the anterior pituitary gland,"Rat anterior pituitary glands were examined by electron microscopy after staining with five different histochemical stains. Histochemical reactions were observed in the cell coat, cell membrane and the membrane surrounding the secretory granules in all anterior pituitary cells following staining with phosphotungstic acid (PTA), chromic acid and PTA, the periodic acid-thiosemicarbazide-silver protein method (PA-TSC-SP) of Thiéry, ruthenium red and concanavalin A. The staining was abolished when the sections were preincubated with pronase, neuraminidase or trypsin and subsequently exposed to PTA, chromic acid and PTA or PA-TSC-SP. The possible functional role of the glycoproteins present in the membrane surrounding the secretory granules is considered.","Glycoproteins in membranes of secretory granules of the anterior pituitary gland Abs: Rat anterior pituitary glands were examined by electron microscopy after staining with five different histochemical stains. Histochemical reactions were observed in the cell coat, cell membrane and the membrane surrounding the secretory granules in all anterior pituitary cells following staining with phosphotungstic acid (PTA), chromic acid and PTA, the periodic acid-thiosemicarbazide-silver protein method (PA-TSC-SP) of Thiéry, ruthenium red and concanavalin A. The staining was abolished when the sections were preincubated with pronase, neuraminidase or trypsin and subsequently exposed to PTA, chromic acid and PTA or PA-TSC-SP. The possible functional role of the glycoproteins present in the membrane surrounding the secretory granules is considered."
1231104,Dawson and  Filipe 1976,An ultrastructural application of silver methenamine to the study of mucin changes in the colonic mucosa adjacent to and remote from carcinoma,"A periodic acid-chromic acid-silver methenamine techniqe for visualizing glycoproteins at the electron microscope level was applied to colonic mucosa taken from areas adjacent to and remote from carcinoma. Normal control mucosa was obtained by biopsy of patients with no known gastrointestinal disease. Non-oxidized control sections were run in parallel. Quantitative and qualitative differences in glycoproteins were detected in the mucosa adjacent to carcinoma ('transitional' mucosa, as we call it) as compared with the normal. Furthermore, the vesicles in both the 'intermediate' and absorptive cells elaborate a glycoprotein product and it seems that a direct relationship exists between the increased vesiculation and the markedly developed 'fuzzy coat' in the 'transitional' mucosa. It is suggested that these findings may represent one of the features of an early stage of carcinogenesis. Histochemical and ultrastructural techniques of the kind used in this study may thus be of value in identifying or predicting malignancy in the colonic epithelium.","An ultrastructural application of silver methenamine to the study of mucin changes in the colonic mucosa adjacent to and remote from carcinoma Abs: A periodic acid-chromic acid-silver methenamine techniqe for visualizing glycoproteins at the electron microscope level was applied to colonic mucosa taken from areas adjacent to and remote from carcinoma. Normal control mucosa was obtained by biopsy of patients with no known gastrointestinal disease. Non-oxidized control sections were run in parallel. Quantitative and qualitative differences in glycoproteins were detected in the mucosa adjacent to carcinoma ('transitional' mucosa, as we call it) as compared with the normal. Furthermore, the vesicles in both the 'intermediate' and absorptive cells elaborate a glycoprotein product and it seems that a direct relationship exists between the increased vesiculation and the markedly developed 'fuzzy coat' in the 'transitional' mucosa. It is suggested that these findings may represent one of the features of an early stage of carcinogenesis. Histochemical and ultrastructural techniques of the kind used in this study may thus be of value in identifying or predicting malignancy in the colonic epithelium."
1231103,Carlsöö and  Ostberg 1976,On the occurrence of argyrophil cells in salivary glands,"Salivary glands (parotid, submandibular and sublingual glands) of nine mammalian species were investigated with respect to presence and localization of argyrophil and argentaffin cells. With the exception of the parotid gland of the rat, no positive staining was observed within the examined glands. In the rat parotid distinctly argyrophil cells could be demonstrated in the intercalated ducts. Histochemical studies of the cells, ultrastructural analysis of their cytoplasmic granules as well as their reactions to certain drugs indicate that these cells are of exocrine rather than of endocrine nature. After a subcutaneous injection of pilocarpine, the intensity of the argyrophil staining was markedly reduced. No specific catecholamine fluorescence could be detected within the cells, not even after pretreatment of the animals with high doses of L-DOPA. The membrane-bounded cytoplasmic granules of the intercalated duct cells furthermore displayed a strong positive staining reaction after treatment of ultrathin Vestopal sections with the periodic acid-chromic acid-silver technique of Rambourg et al. (1969).","On the occurrence of argyrophil cells in salivary glands Abs: Salivary glands (parotid, submandibular and sublingual glands) of nine mammalian species were investigated with respect to presence and localization of argyrophil and argentaffin cells. With the exception of the parotid gland of the rat, no positive staining was observed within the examined glands. In the rat parotid distinctly argyrophil cells could be demonstrated in the intercalated ducts. Histochemical studies of the cells, ultrastructural analysis of their cytoplasmic granules as well as their reactions to certain drugs indicate that these cells are of exocrine rather than of endocrine nature. After a subcutaneous injection of pilocarpine, the intensity of the argyrophil staining was markedly reduced. No specific catecholamine fluorescence could be detected within the cells, not even after pretreatment of the animals with high doses of L-DOPA. The membrane-bounded cytoplasmic granules of the intercalated duct cells furthermore displayed a strong positive staining reaction after treatment of ultrathin Vestopal sections with the periodic acid-chromic acid-silver technique of Rambourg et al. (1969)."
1231101,Friess 1976,Interdigitating reticulum cells in the popliteal lymph node of the rat. An ultrastructural and cytochemical study,"Electronmicroscopic and cytochemical studies were performed to localize interdigitating reticulum cells (IDC) in the popliteal lymph node of the rat. The morphological features of the IDC of the rat correspond to those described for other species, but also show similarities to normal macrophages in the rat. This is considered to be an argument in favour of the common origin of IDC's and macrophages. Ultrahistochemical studies with horseradish peroxidase (HRP) reveal no phagocytotic capacity of IDC's. After perfusion fixation containing ruthenium red (RR) the surface coat stains heavily: RR is also found deep in the membrane invaginations of the IDC, indicating the presence of polyanionic sialoglycoproteins. The post-capillary-venules (PVC) are very permeable to both HRP and RR. The phosphotungstic acid-chromic acid stain (PTA-CrA) also reveals glycoproteins in the surface coat; these glycoproteins are susceptible to alpha-neuraminidase, whereas glycoproteins in the Golgi complexes, lysosomes and in the vesicular complexes of IDC are not. The glycoproteins of the latter are susceptible to 0.1 N NaOH. These findings indicate that IDC produce different kinds of glycoprotein, one of which may be secreted and act as a factor for stimulating peripheral T-lymphocytes. Intimate contact between IDC's and PCV's could be observed. It is therefore conceivable that IDC's play an important role in the homing of T-lymphocytes.","Interdigitating reticulum cells in the popliteal lymph node of the rat. An ultrastructural and cytochemical study Abs: Electronmicroscopic and cytochemical studies were performed to localize interdigitating reticulum cells (IDC) in the popliteal lymph node of the rat. The morphological features of the IDC of the rat correspond to those described for other species, but also show similarities to normal macrophages in the rat. This is considered to be an argument in favour of the common origin of IDC's and macrophages. Ultrahistochemical studies with horseradish peroxidase (HRP) reveal no phagocytotic capacity of IDC's. After perfusion fixation containing ruthenium red (RR) the surface coat stains heavily: RR is also found deep in the membrane invaginations of the IDC, indicating the presence of polyanionic sialoglycoproteins. The post-capillary-venules (PVC) are very permeable to both HRP and RR. The phosphotungstic acid-chromic acid stain (PTA-CrA) also reveals glycoproteins in the surface coat; these glycoproteins are susceptible to alpha-neuraminidase, whereas glycoproteins in the Golgi complexes, lysosomes and in the vesicular complexes of IDC are not. The glycoproteins of the latter are susceptible to 0.1 N NaOH. These findings indicate that IDC produce different kinds of glycoprotein, one of which may be secreted and act as a factor for stimulating peripheral T-lymphocytes. Intimate contact between IDC's and PCV's could be observed. It is therefore conceivable that IDC's play an important role in the homing of T-lymphocytes."
1231098,Koehler et al. 1976,Association of latent cellulase activity with plasma membranes from kidney bean abscission zones,"Membranes isolated from abscission zones of Phaseolus vulgaris L., cv. Red Kidney, contained cellulase activity. This particulate activity was enhanced 10- to 20-fold by treatment with Triton X-100. Sucrose density gradient analyses of cell fractions showed that the membranes with which cellulase was associated had a peak equilibrium density of 1.16 to 1.17 g/cm(3) which coincided with that of ion-activated ATPase, a marker for plasma membranes. The membrane fraction having the highest cellulase activity also contained a high proportion of plasma membranes as shown by electron microscopy of sucrose density gradient fractions after staining by periodic acid-chromic acid-phosphotungstic acid. It was concluded that the particulate cellulase was associated with the plasma membrane.","Association of latent cellulase activity with plasma membranes from kidney bean abscission zones Abs: Membranes isolated from abscission zones of Phaseolus vulgaris L., cv. Red Kidney, contained cellulase activity. This particulate activity was enhanced 10- to 20-fold by treatment with Triton X-100. Sucrose density gradient analyses of cell fractions showed that the membranes with which cellulase was associated had a peak equilibrium density of 1.16 to 1.17 g/cm(3) which coincided with that of ion-activated ATPase, a marker for plasma membranes. The membrane fraction having the highest cellulase activity also contained a high proportion of plasma membranes as shown by electron microscopy of sucrose density gradient fractions after staining by periodic acid-chromic acid-phosphotungstic acid. It was concluded that the particulate cellulase was associated with the plasma membrane."
1231097,Pisam and  Ripoche 1976,Redistribution of surface macromolecules in dissociated epithelial cells,"A number of ultrastructural and cytochemical techniques were used to study intact epithelial cells lining the frog urinary bladder: high resolution autoradiography after administration of [3H]glucosamine or [3H]fucose; 125I iodination of external protein; concanavalin A-peroxidase, periodic acid-chromic acid silver methenamine; and colloidal thorium. Results indicate that the material (probably glycoprotein) coating the apical surface differs from that which lines the lateral and basal surfaces. After dissociation and isolation of the epithelial cells, the material previously confined to the apical surface invaded progressively the opened &quot;tight junctions&quot; (about 5 min), then the lateral membranes (about 40 min), and finally the basal membrane (about 80 min): at that time, the whole cell surface was entirely enveloped by the apical material. Since, on the one hand, the reacting material was confined to the apical surface when the tight junctions were closed (in intact epithelial cells) and since, on the other hand, the apical material was sliding down the laterobasal membranes when the tight junctions were opened (in dissociated cells), it may be concluded that tight junctions contribute to maintain the cell surface specialization in epithelia.","Redistribution of surface macromolecules in dissociated epithelial cells Abs: A number of ultrastructural and cytochemical techniques were used to study intact epithelial cells lining the frog urinary bladder: high resolution autoradiography after administration of [3H]glucosamine or [3H]fucose; 125I iodination of external protein; concanavalin A-peroxidase, periodic acid-chromic acid silver methenamine; and colloidal thorium. Results indicate that the material (probably glycoprotein) coating the apical surface differs from that which lines the lateral and basal surfaces. After dissociation and isolation of the epithelial cells, the material previously confined to the apical surface invaded progressively the opened &quot;tight junctions&quot; (about 5 min), then the lateral membranes (about 40 min), and finally the basal membrane (about 80 min): at that time, the whole cell surface was entirely enveloped by the apical material. Since, on the one hand, the reacting material was confined to the apical surface when the tight junctions were closed (in intact epithelial cells) and since, on the other hand, the apical material was sliding down the laterobasal membranes when the tight junctions were opened (in dissociated cells), it may be concluded that tight junctions contribute to maintain the cell surface specialization in epithelia."
1231096,Coghill and  Hopwood 1977,Electron histochemistry of mucosubstances in normal human rectal epithelium,"The electron microscopic histochemistry of mucosubstances in sigmoidoscopically and microscopically normal rectal biopsies was studied using techniques currently available. The deposition of Alcian Blue and Ruthenium Red and the distribution of Concanavalin A receptors were limited to the epithelial cell borders. Mucosubstances in the fuzzy coat, Golgi apparatus, lysosomes and secretory vesicles were demonstrated by the periodic acid-chromic acid oxidation methods. Glycogen was demonstrated in the epithelium by periodate oxidation methods and the complex cyanide technique. There was little difference in the distribution of mucosubstances in the epithelial cells at any level of the crypts. Phosphotungstic acid staining under controlled conditions gave a similar distribution of mucosubstances to those revealed by the oxidation techniques.","Electron histochemistry of mucosubstances in normal human rectal epithelium Abs: The electron microscopic histochemistry of mucosubstances in sigmoidoscopically and microscopically normal rectal biopsies was studied using techniques currently available. The deposition of Alcian Blue and Ruthenium Red and the distribution of Concanavalin A receptors were limited to the epithelial cell borders. Mucosubstances in the fuzzy coat, Golgi apparatus, lysosomes and secretory vesicles were demonstrated by the periodic acid-chromic acid oxidation methods. Glycogen was demonstrated in the epithelium by periodate oxidation methods and the complex cyanide technique. There was little difference in the distribution of mucosubstances in the epithelial cells at any level of the crypts. Phosphotungstic acid staining under controlled conditions gave a similar distribution of mucosubstances to those revealed by the oxidation techniques."
1231093,Peele et al. 1977,"Metabolism of naturally occurring propenylbenzene derivatives. III. Allylbenzene, propenyl benzene, and related metabolic products","The acidic and neutral urinary metabolites of allylbenzene, propenylbenzene, 1'-hydroxyallylbenzene, and cynnamyl alcohol were identified and related through a common metabolic scheme. The rat metabolizes allylbenzene to 1'-hydroxyallylbenzene which can rearrange to yield cinnamyl alcohol whick is further metabolized. This mechanism is proposed to account for the appearance of ""propenyl type"" metabolites from allylbenzene compounds. Propenylbenzene is oxidized to cynnamyl alcohol. Both 1'-hydroxyallylbenzene and cunnamyl alcohol are excreted unchanged in the neutral extract when given to rats. Allylbenzene and 1'-hydroxyallylbenzene yield basic ninhydrin-positive metabolites. Allylbenzene is first oxidized on the benzylic carbon to form 1'-hydroxyallylbenzene, which is further oxidized to form phenyl vinyl ketone, which condenses with the secondary amines piperidine and dimethylamine to form tertiary aminopropiophenones (Mannich bases). Analogous compounds, cinnamyl alcohol and propenylbenzene, do not yield Mannich base metabolites. This proposed metabolic scheme is consistent with the chemical mechanism operative in the synthesis of Mannich base from allylbenzene via chromic acid oxidation followed by amine addition.","Metabolism of naturally occurring propenylbenzene derivatives. III. Allylbenzene, propenyl benzene, and related metabolic products Abs: The acidic and neutral urinary metabolites of allylbenzene, propenylbenzene, 1'-hydroxyallylbenzene, and cynnamyl alcohol were identified and related through a common metabolic scheme. The rat metabolizes allylbenzene to 1'-hydroxyallylbenzene which can rearrange to yield cinnamyl alcohol whick is further metabolized. This mechanism is proposed to account for the appearance of ""propenyl type"" metabolites from allylbenzene compounds. Propenylbenzene is oxidized to cynnamyl alcohol. Both 1'-hydroxyallylbenzene and cunnamyl alcohol are excreted unchanged in the neutral extract when given to rats. Allylbenzene and 1'-hydroxyallylbenzene yield basic ninhydrin-positive metabolites. Allylbenzene is first oxidized on the benzylic carbon to form 1'-hydroxyallylbenzene, which is further oxidized to form phenyl vinyl ketone, which condenses with the secondary amines piperidine and dimethylamine to form tertiary aminopropiophenones (Mannich bases). Analogous compounds, cinnamyl alcohol and propenylbenzene, do not yield Mannich base metabolites. This proposed metabolic scheme is consistent with the chemical mechanism operative in the synthesis of Mannich base from allylbenzene via chromic acid oxidation followed by amine addition."
1231090,Michaels 1977,Glycoprotein containing vesicles in the surface epithelial cells of the ascending colon of the rat,"Recently, radioautographic studies have shown that cell coat glycoproteins are transported to the cell surface by vesicles both in the amoeba (Flickinger, '75) and in the epithelial cells of the ascending colon of the mouse (Michaels and Leblond, '76). In the current morphological and cytochemical study of the surface epithelial cells of the rat ascending colon, it is shown that filamentous material, resembling the cell coat, is contained in saccules toward the mature face of the Golgi apparatus and vesicles close to the apparatus and near the terminal web. The vesicles are limited by a unit membrane composed of asymmetric osmiophilic leaflets and similar to the plasma membrane. When stained by the periodic acid-chromic acid-silver methenamine technique, silver was precipitated on the cell components containing the filamentous material indicating the presence of glycoproteins. Narrow invaginations from the cell surface that may correspond to vesicles undergoing exocytosis were also positive for glycoproteins. The distribution of the filamentous material that was glycoprotein positive parallels the pathway followed by material that had been found to be labeled with a tritiated glycoprotein precursor (3H-fucose) in the epithelial cells of the ascending colon of the mouse. It is suggested that the system of vesicles in the rat colon cells is acting in a manner similar to the vesicles in the mouse cells to transport cell coat glycoproteins from the Golgi apparatus to the cell surface.","Glycoprotein containing vesicles in the surface epithelial cells of the ascending colon of the rat Abs: Recently, radioautographic studies have shown that cell coat glycoproteins are transported to the cell surface by vesicles both in the amoeba (Flickinger, '75) and in the epithelial cells of the ascending colon of the mouse (Michaels and Leblond, '76). In the current morphological and cytochemical study of the surface epithelial cells of the rat ascending colon, it is shown that filamentous material, resembling the cell coat, is contained in saccules toward the mature face of the Golgi apparatus and vesicles close to the apparatus and near the terminal web. The vesicles are limited by a unit membrane composed of asymmetric osmiophilic leaflets and similar to the plasma membrane. When stained by the periodic acid-chromic acid-silver methenamine technique, silver was precipitated on the cell components containing the filamentous material indicating the presence of glycoproteins. Narrow invaginations from the cell surface that may correspond to vesicles undergoing exocytosis were also positive for glycoproteins. The distribution of the filamentous material that was glycoprotein positive parallels the pathway followed by material that had been found to be labeled with a tritiated glycoprotein precursor (3H-fucose) in the epithelial cells of the ascending colon of the mouse. It is suggested that the system of vesicles in the rat colon cells is acting in a manner similar to the vesicles in the mouse cells to transport cell coat glycoproteins from the Golgi apparatus to the cell surface."
1231089,Dmitriev et al. 1977,Cell-wall lipopolysaccharide of the 'Shigella-like' Escherichia coli 058. Structure of the polysaccharide chain,"Two lipopolysaccharide preparations were obtained from Escherichia coli 058 by extraction with 45% aqueous phenol and fractional precipitation with cetyltrimethyl ammonium bromide (Cetavlon). Chemical analysis and polyacrylamide gel electrophoresis in the presence of sodium dodecylsulfate showed that the two preparations differed only in the extent of the O-specific polysaccharide moiety. The O-specific polysaccharide was characterized with proton magnetic resonance and infrared spectroscopy, optical rotation and paper electrophoresis. Using gas-liquid chromatography and ion-exchange chromatography, it was shown to contain D-mannose, 2-acetamido-2-deoxy-D-glucose, 3-O-(R-1'-carboxyethyl)-L-rhamnose (rhamnolactylic acid), and O-acetyl groups in the molar ratios of 2:1:1:1. The polysaccharide and oligosaccharides obtained from it were subjected to methylation and chromic acid oxidation. The results obtained indicated that the polysaccharide consists of tetrasaccharide repeating units in which the trisaccharide beta-GlcNAc1 - 4alphaMan-1 - 4(2/3-O-Ac)-Man is substituted at C-3 of the non-acetylated mannose with rhamnolactylic acid. The repeating units are joined through alpha-mannosyl-1 - 3-glucosamine bonds. This structure is identical with that of the cell wall polysaccharide of Shigella dysenteriae type 5.","Cell-wall lipopolysaccharide of the 'Shigella-like' Escherichia coli 058. Structure of the polysaccharide chain Abs: Two lipopolysaccharide preparations were obtained from Escherichia coli 058 by extraction with 45% aqueous phenol and fractional precipitation with cetyltrimethyl ammonium bromide (Cetavlon). Chemical analysis and polyacrylamide gel electrophoresis in the presence of sodium dodecylsulfate showed that the two preparations differed only in the extent of the O-specific polysaccharide moiety. The O-specific polysaccharide was characterized with proton magnetic resonance and infrared spectroscopy, optical rotation and paper electrophoresis. Using gas-liquid chromatography and ion-exchange chromatography, it was shown to contain D-mannose, 2-acetamido-2-deoxy-D-glucose, 3-O-(R-1'-carboxyethyl)-L-rhamnose (rhamnolactylic acid), and O-acetyl groups in the molar ratios of 2:1:1:1. The polysaccharide and oligosaccharides obtained from it were subjected to methylation and chromic acid oxidation. The results obtained indicated that the polysaccharide consists of tetrasaccharide repeating units in which the trisaccharide beta-GlcNAc1 - 4alphaMan-1 - 4(2/3-O-Ac)-Man is substituted at C-3 of the non-acetylated mannose with rhamnolactylic acid. The repeating units are joined through alpha-mannosyl-1 - 3-glucosamine bonds. This structure is identical with that of the cell wall polysaccharide of Shigella dysenteriae type 5."
1231088,Benchimol et al. 1977,An electron microscopic investigation of the surface coat of the electrocyte of electrophorus electricus,"The surface coat of the electrocyte of the main electric organ of Electrophorus electricus was studied using cytochemical methods (periodic acid-silver methanamine, periodic acid-chromic acid-silver methenamine, periodic acid-thiosemicarbazide-silver proteinate, Concanavalin A - horseradish peroxidase, ruthenium red, Alcian-blue lanthanum nitrate, colloidal iron hydroxide and cationized ferritin). The surface of the electrocyte presents perpendicularly oriented tubular invaginations of the cell membrane. The fibrous coat 50-100 nm thick, penetrates into the lumen of the invaginations. It is also observed in the synaptic clefts existent in the posterior face of the electrolyte. The coating of the surface membrane gives a positive reaction with all techniques used. Binding of colloidal iron hydroxide particles was observed only in the outer layer of the coat. With the Alcian-blue lanthanum nitrate technique , microtubules were observed in the cytoplasm of the electrocyte. The results indicate that the surface coat of the electrocyte contains mucopolysaccharides, glycoproteins, acid mucopolysaccharides and anionic sites detected at low (colloidal iron hydroxyde) and neutral (cationized ferritin) pH.","An electron microscopic investigation of the surface coat of the electrocyte of electrophorus electricus Abs: The surface coat of the electrocyte of the main electric organ of Electrophorus electricus was studied using cytochemical methods (periodic acid-silver methanamine, periodic acid-chromic acid-silver methenamine, periodic acid-thiosemicarbazide-silver proteinate, Concanavalin A - horseradish peroxidase, ruthenium red, Alcian-blue lanthanum nitrate, colloidal iron hydroxide and cationized ferritin). The surface of the electrocyte presents perpendicularly oriented tubular invaginations of the cell membrane. The fibrous coat 50-100 nm thick, penetrates into the lumen of the invaginations. It is also observed in the synaptic clefts existent in the posterior face of the electrolyte. The coating of the surface membrane gives a positive reaction with all techniques used. Binding of colloidal iron hydroxide particles was observed only in the outer layer of the coat. With the Alcian-blue lanthanum nitrate technique , microtubules were observed in the cytoplasm of the electrocyte. The results indicate that the surface coat of the electrocyte contains mucopolysaccharides, glycoproteins, acid mucopolysaccharides and anionic sites detected at low (colloidal iron hydroxyde) and neutral (cationized ferritin) pH."
1231086,Langenberg and  Sharpee 1978,Chromic-acid formaldehyde fixation of nucleic acids of bacteriophage phi6 and infectious bovine rhinotracheitis virus,"Bacteriophage phi6 nucleic acid was present as a torus after chromic acid-formaldehyde-OSO4 fixation and acetone and propylene oxide dehydration. A herpes virus, infectious bovine rhinotracheitis virus, had its DNA mostly as a torus, collapsed in the centre, or as a network, after glutaraldehyde-OSO4 fixation, but in an uncollapsed torus or network formation after chromic acid-formaldehyde-OSO4. This fixative stabilized nucleic acids, allowing acetone dehydration and plastic embedding without collapse of nucleic acid to the centre of the virion.","Chromic-acid formaldehyde fixation of nucleic acids of bacteriophage phi6 and infectious bovine rhinotracheitis virus Abs: Bacteriophage phi6 nucleic acid was present as a torus after chromic acid-formaldehyde-OSO4 fixation and acetone and propylene oxide dehydration. A herpes virus, infectious bovine rhinotracheitis virus, had its DNA mostly as a torus, collapsed in the centre, or as a network, after glutaraldehyde-OSO4 fixation, but in an uncollapsed torus or network formation after chromic acid-formaldehyde-OSO4. This fixative stabilized nucleic acids, allowing acetone dehydration and plastic embedding without collapse of nucleic acid to the centre of the virion."
1231085,Yunghans et al. 1978,Nature of the phosphotungstic acid-chromic acid (PACP) stain for plasma membranes of plants and mammalian sperm,"The selective staining of plasma membranes of plants and porcine spermatozoa given by a mixture consisting of 1% phosphotungstic acid in 10% chromic acid (PACP) applied following periodic acid destaining of glutaraldehyde-osmium tetroxide-fixed electron microscope sections is reduced or eliminated by prior extraction of the tissues with lipid solvents, including ethanol. The ethanol-soluble fraction of sperm contains constituents which restore the PACP-staining reaction when added to ethanol-extracted and lyophilized sperm. Analysis of the ethanol extracts by thin layer chromatography revealed two major components which reacted with both phosphotungstic acid (PTA) and alpha-naphthol detection reagents. These PTA-positive constituents were concentrated in plasma membranes of sperm; components with similar mobilities were found in fractions of plasma membranes from plants. Addition of the PTA-positive constituents from either sperm or plants to extracted and lyophilized sperm restored the PACP staining. The findings are interpreted to mean that one or more low molecular weight constituents (saccharides or glycolipids), rather than glycoproteins, concentrated in plaslma membranes are responsible for the unique PACP staining in both plants and porcine sperm.","Nature of the phosphotungstic acid-chromic acid (PACP) stain for plasma membranes of plants and mammalian sperm Abs: The selective staining of plasma membranes of plants and porcine spermatozoa given by a mixture consisting of 1% phosphotungstic acid in 10% chromic acid (PACP) applied following periodic acid destaining of glutaraldehyde-osmium tetroxide-fixed electron microscope sections is reduced or eliminated by prior extraction of the tissues with lipid solvents, including ethanol. The ethanol-soluble fraction of sperm contains constituents which restore the PACP-staining reaction when added to ethanol-extracted and lyophilized sperm. Analysis of the ethanol extracts by thin layer chromatography revealed two major components which reacted with both phosphotungstic acid (PTA) and alpha-naphthol detection reagents. These PTA-positive constituents were concentrated in plasma membranes of sperm; components with similar mobilities were found in fractions of plasma membranes from plants. Addition of the PTA-positive constituents from either sperm or plants to extracted and lyophilized sperm restored the PACP staining. The findings are interpreted to mean that one or more low molecular weight constituents (saccharides or glycolipids), rather than glycoproteins, concentrated in plaslma membranes are responsible for the unique PACP staining in both plants and porcine sperm."
1231083,Nagahashi et al. 1978,Purification of plasma membranes from roots of barley: specificity of the phosphotungstic Acid-chromic Acid stain,"Plasma membrane vesicles from roots of barley (Hordeum vulgare L., var. Arivat) had an equilibrium density in sucrose of about 1.16 grams per cubic centimeter, but could not be purified satisfactorily with the procedure developed for roots of other plant species. The reported procedure involving differential centrifugation to remove mitochondria (peak density of 1.18 grams per cubic centimeter) and subsequent density gradient centrifugation to purify plasma membrane vesicles was modified to include a narrower differential centrifugation fraction (13,000 to 40,000g instead of 13,000 to 80,000g) and a narrower density range in the sucrose gradient (1.15 to 1.18 grams per cubic centimeter instead of 1.15 to 1.20 grams per cubic centimeter). The fraction obtained by the modified procedure was between 60 and 70% pure as determined by staining with the phosphotungstic acid-chromic acid procedure, which was judged to be reliable for identifying plasma membrane vesicles in subcellular fractions from barley roots. The plasma membrane fraction was enriched in K(+)-stimulated ATPase activity at pH 6.5. The presence of nonspecific ATP-hydrolyzing activity in the plasma membrane fraction made it difficult to determine if the ATPase had properties in common with those reported for cation absorption in barley roots.","Purification of plasma membranes from roots of barley: specificity of the phosphotungstic Acid-chromic Acid stain Abs: Plasma membrane vesicles from roots of barley (Hordeum vulgare L., var. Arivat) had an equilibrium density in sucrose of about 1.16 grams per cubic centimeter, but could not be purified satisfactorily with the procedure developed for roots of other plant species. The reported procedure involving differential centrifugation to remove mitochondria (peak density of 1.18 grams per cubic centimeter) and subsequent density gradient centrifugation to purify plasma membrane vesicles was modified to include a narrower differential centrifugation fraction (13,000 to 40,000g instead of 13,000 to 80,000g) and a narrower density range in the sucrose gradient (1.15 to 1.18 grams per cubic centimeter instead of 1.15 to 1.20 grams per cubic centimeter). The fraction obtained by the modified procedure was between 60 and 70% pure as determined by staining with the phosphotungstic acid-chromic acid procedure, which was judged to be reliable for identifying plasma membrane vesicles in subcellular fractions from barley roots. The plasma membrane fraction was enriched in K(+)-stimulated ATPase activity at pH 6.5. The presence of nonspecific ATP-hydrolyzing activity in the plasma membrane fraction made it difficult to determine if the ATPase had properties in common with those reported for cation absorption in barley roots."
1231080,Cosner and  Troxler 1978,"Phycobiliprotein synthesis in protoplasts of the unicellular cyanophyte, Anacystis nidulans","Stable and metabolically active protoplasts were prepared from the unicellular cyanophyte, Anacystis nidulans, by enzymatic digestion of the cell wall with 0.1% lysozyme. The yield of protoplasts from intact algal cells was approx. 50%. Incorporation of L-[U-14C]leucine into cold trichloroacetic acid-insoluble material from protoplasts preparations was linear for 1.5 h and continued for an additional 2.5 h. Incorporation of radiolabeled leucine into hot trichloroacetic acid-insoluble material from protoplast preparations demonstrated protein synthesis in protoplasts in vitro. Phycocyanin is the principal phycobiliprotein and allophycocyanin is a minor phycobiliprotein in A. nidulans cells. The light-absorbing chromophore of both of these phycobiliproteins is the linear tetrapyrrole (bile pigment), phycocyanobilin. Radiolabeled phycocyanin and allophycocyanin were isolated from protoplast preparations which had been incubated with L-[U-14]leucine or delta-amino[4-14C] levulinic acid (a precursor of phycocyanobilin). The radio-labeled phycobiliproteins were purified by ammonium sulfate fractionation and ion-exchange chromatography on brushite columns. The specific radioactivity of phycocyanin and allophycocyanin in brushite column eluates (protoplasts incubated with radiolabeled leucine) was 106 000 and 82 000 dpm/mg, respectively. The specific radioactivity of phycocyanin and allophycocyanin in brushite column eluates (protoplasts incubated with radiolabeled delta-aminolevulinic acid) was 33 000 and 38 000 dpm/mg, respectively. Phycobiliproteins from protoplasts incubated with radiolabeled leucine were examined by sodium dodecyl sulfate-polyacrylamide gel electrophoresis. 25% of the incorporated radioactivity in protoplast lysates and approx. 60% of the incorporated radioactivity in protoplast lysates and approx. 60% of the incorporated ratioactivity in phycocyanin and allophycocyanin (in brushite column eluates) comigrated with the subunits of these phycobiliproteins on sodium dodecyl sulfate-polyacrylamide gels. Chromic acid degradation of phycobiliproteins from protoplast preparations incubated with delta-amino[4-14C] levulinic acid yielded radiolabeled imides which were derived from the phycocyanobilin chromophore. Imides from radiolabeled phycobiliproteins isolated from protoplast preparations incubated with L-[U-14C]leucine did not contain radioactivity. These results show that both the apoprotein and tetrapyrrolic moieties of phycocyanin and allophycocyanin were synthesized in A. nidulans protoplasts in vitro.","Phycobiliprotein synthesis in protoplasts of the unicellular cyanophyte, Anacystis nidulans Abs: Stable and metabolically active protoplasts were prepared from the unicellular cyanophyte, Anacystis nidulans, by enzymatic digestion of the cell wall with 0.1% lysozyme. The yield of protoplasts from intact algal cells was approx. 50%. Incorporation of L-[U-14C]leucine into cold trichloroacetic acid-insoluble material from protoplasts preparations was linear for 1.5 h and continued for an additional 2.5 h. Incorporation of radiolabeled leucine into hot trichloroacetic acid-insoluble material from protoplast preparations demonstrated protein synthesis in protoplasts in vitro. Phycocyanin is the principal phycobiliprotein and allophycocyanin is a minor phycobiliprotein in A. nidulans cells. The light-absorbing chromophore of both of these phycobiliproteins is the linear tetrapyrrole (bile pigment), phycocyanobilin. Radiolabeled phycocyanin and allophycocyanin were isolated from protoplast preparations which had been incubated with L-[U-14]leucine or delta-amino[4-14C] levulinic acid (a precursor of phycocyanobilin). The radio-labeled phycobiliproteins were purified by ammonium sulfate fractionation and ion-exchange chromatography on brushite columns. The specific radioactivity of phycocyanin and allophycocyanin in brushite column eluates (protoplasts incubated with radiolabeled leucine) was 106 000 and 82 000 dpm/mg, respectively. The specific radioactivity of phycocyanin and allophycocyanin in brushite column eluates (protoplasts incubated with radiolabeled delta-aminolevulinic acid) was 33 000 and 38 000 dpm/mg, respectively. Phycobiliproteins from protoplasts incubated with radiolabeled leucine were examined by sodium dodecyl sulfate-polyacrylamide gel electrophoresis. 25% of the incorporated radioactivity in protoplast lysates and approx. 60% of the incorporated radioactivity in protoplast lysates and approx. 60% of the incorporated ratioactivity in phycocyanin and allophycocyanin (in brushite column eluates) comigrated with the subunits of these phycobiliproteins on sodium dodecyl sulfate-polyacrylamide gels. Chromic acid degradation of phycobiliproteins from protoplast preparations incubated with delta-amino[4-14C] levulinic acid yielded radiolabeled imides which were derived from the phycocyanobilin chromophore. Imides from radiolabeled phycobiliproteins isolated from protoplast preparations incubated with L-[U-14C]leucine did not contain radioactivity. These results show that both the apoprotein and tetrapyrrolic moieties of phycocyanin and allophycocyanin were synthesized in A. nidulans protoplasts in vitro."
1231079,Verma et al. 1978,Isolation and characterization of the membrane envelope enclosing the bacteroids in soybean root nodules,"The membrane envelope enclosing the bacteroids in soybean root nodules is shown by ultrastructural and biochemical studies to be derived from, and to retain the characteristics of, the host cell plasma membrane. During the early stages of the infection process, which occurs through an invagination, Rhizobium becomes surrounded by the host cell wall and plasma membrane, forming the infection thread. The cell wall of the infection thread is degraded by cellulolytic enzyme(s), leaving behind the enclosed plasma membrane, the membrane envelope. Cellulase activity in young nodules increases two- to threefold as compared to uninfected roots, and this activity is localized in the cell wall matrix of the infection threads. Membrane envelopes were isolated by first preparing bacteroids enclosed in the envelopes on a discontinuous sucrose gradient followed by passage through a hypodermic needle, which released the bacteroids from the membranes. This membrane then sedimented at the interface of 34--45% sucrose (mean density of 1.14 g/cm3). Membranes were characterized by phosphotungstic acid (PTA)-chromic acid staining. ATPase activity, and localization, sensitivity to nonionic detergent Nonidet P-40 (NP-40) and sodium dodecyl sulfate (SDS) gel electrophoresis. These analyses revealed a close similarity between plasma membrane and the membrane envelope. Incorporation of radioactive amino acids into the membrane envelope proteins was sensitive to cycloheximide, suggesting that the biosynthesis of these proteins is primarily under host-cell control. No immunoreactive material to leghemoglobin antibodies was found inside or associated with the isolated bacteroids enclosed in the membrane envelope, and its location is confined to the host cell cytoplasmic matrix.","Isolation and characterization of the membrane envelope enclosing the bacteroids in soybean root nodules Abs: The membrane envelope enclosing the bacteroids in soybean root nodules is shown by ultrastructural and biochemical studies to be derived from, and to retain the characteristics of, the host cell plasma membrane. During the early stages of the infection process, which occurs through an invagination, Rhizobium becomes surrounded by the host cell wall and plasma membrane, forming the infection thread. The cell wall of the infection thread is degraded by cellulolytic enzyme(s), leaving behind the enclosed plasma membrane, the membrane envelope. Cellulase activity in young nodules increases two- to threefold as compared to uninfected roots, and this activity is localized in the cell wall matrix of the infection threads. Membrane envelopes were isolated by first preparing bacteroids enclosed in the envelopes on a discontinuous sucrose gradient followed by passage through a hypodermic needle, which released the bacteroids from the membranes. This membrane then sedimented at the interface of 34--45% sucrose (mean density of 1.14 g/cm3). Membranes were characterized by phosphotungstic acid (PTA)-chromic acid staining. ATPase activity, and localization, sensitivity to nonionic detergent Nonidet P-40 (NP-40) and sodium dodecyl sulfate (SDS) gel electrophoresis. These analyses revealed a close similarity between plasma membrane and the membrane envelope. Incorporation of radioactive amino acids into the membrane envelope proteins was sensitive to cycloheximide, suggesting that the biosynthesis of these proteins is primarily under host-cell control. No immunoreactive material to leghemoglobin antibodies was found inside or associated with the isolated bacteroids enclosed in the membrane envelope, and its location is confined to the host cell cytoplasmic matrix."
1231078,Abul-Hajj 1979,Steroid delta 4-5 beta-reductase in human mammary tumors,"Steroid delta 4-5 alpha- and delta 4-5 beta-reductase activity was determined in 16 human mammary tumors and 8 DMBA-induced rat mammary tumors using a spectrophotometric assay. Steroid delta 4-5 alpha-reductase was present in all tumors investigated while delta 4-5 beta-reductase was detected in only 6 estrogen receptor negative human breast tumors and absent in all estrogen receptor positive human breast tumors as well as in all rat mammary tumors. Further support for the presence of delta 4-5 beta-reductase was established by using a dual-labelling technique consisting of incubating tumor slices with [14C] testosterone and adding [3H] etiocholanolone, [3H] testosterone and [3H]-5 alpha-dihydrotestosterone at the end of the reaction. Following extraction and chromic acid oxidation, 4-androstenedione, 5 beta-androstanedione and 5 alpha-androstanedione were isolated and purified, and the constancy of the 14C/3H ratio was used as proof of 5 alpha-reductase and 5 beta-reductase. These results were shown to be consistent with the data obtained using the spectrophotometric assay.","Steroid delta 4-5 beta-reductase in human mammary tumors Abs: Steroid delta 4-5 alpha- and delta 4-5 beta-reductase activity was determined in 16 human mammary tumors and 8 DMBA-induced rat mammary tumors using a spectrophotometric assay. Steroid delta 4-5 alpha-reductase was present in all tumors investigated while delta 4-5 beta-reductase was detected in only 6 estrogen receptor negative human breast tumors and absent in all estrogen receptor positive human breast tumors as well as in all rat mammary tumors. Further support for the presence of delta 4-5 beta-reductase was established by using a dual-labelling technique consisting of incubating tumor slices with [14C] testosterone and adding [3H] etiocholanolone, [3H] testosterone and [3H]-5 alpha-dihydrotestosterone at the end of the reaction. Following extraction and chromic acid oxidation, 4-androstenedione, 5 beta-androstanedione and 5 alpha-androstanedione were isolated and purified, and the constancy of the 14C/3H ratio was used as proof of 5 alpha-reductase and 5 beta-reductase. These results were shown to be consistent with the data obtained using the spectrophotometric assay."
1231077,Giraud et al. 1979,"Ultrastructure and cytochemistry of the gastric mucosa of a reptile, Tiliqua scincoides","The gastric mucosa of a reptile, the lizard Tiliqua scincoides, has been examined by light and electron microscopy. The gastric pits lead into glands that are extensively coiled in the proximal stomach but become progressively shorter and straighter in the distal stomach. The following epithelial cell types have been identified: (i) Surface mucous cells (SMC) line the entire lumenal surface as well as the pits. They contain mucus granules that stain with periodic acid-Schiff and, like the granules of mammalian SMC, commonly contain an electron dense core that appears not to be mucus (periodic acid-chromic acid-silver methenamine nonreactive). (ii) Glandular mucous cells are present in glands throughout the mucosa. They are probably homologous with the mucous neck and antral gland cells of mammals; like SMC their mucus granules contain nonglycoprotein cores. (iii) Oxynticopeptic cells (OPC) are the predominant cell type in the proximal gland but become infrequent distally. Their fine structure resembles that of OPC in other nonmammalian vertebrates, with features like those of both parietal cells and zymogen cells of mammals. (iv) Endocrine cells of three different types have been identified. Two of these show close similarities to the EC and ECL cells of mammals.","Ultrastructure and cytochemistry of the gastric mucosa of a reptile, Tiliqua scincoides Abs: The gastric mucosa of a reptile, the lizard Tiliqua scincoides, has been examined by light and electron microscopy. The gastric pits lead into glands that are extensively coiled in the proximal stomach but become progressively shorter and straighter in the distal stomach. The following epithelial cell types have been identified: (i) Surface mucous cells (SMC) line the entire lumenal surface as well as the pits. They contain mucus granules that stain with periodic acid-Schiff and, like the granules of mammalian SMC, commonly contain an electron dense core that appears not to be mucus (periodic acid-chromic acid-silver methenamine nonreactive). (ii) Glandular mucous cells are present in glands throughout the mucosa. They are probably homologous with the mucous neck and antral gland cells of mammals; like SMC their mucus granules contain nonglycoprotein cores. (iii) Oxynticopeptic cells (OPC) are the predominant cell type in the proximal gland but become infrequent distally. Their fine structure resembles that of OPC in other nonmammalian vertebrates, with features like those of both parietal cells and zymogen cells of mammals. (iv) Endocrine cells of three different types have been identified. Two of these show close similarities to the EC and ECL cells of mammals."
1231076,Underwood 1979,Separation of polychlorinated biphenyls from DDT and its analogs using chromic acid and silica gel,"PESTAB. A method to separate and determine polychlorinated biphenyls (PCB's) in the presence of DDT and its analogs is described. A glass wool plug is placed in the bottom of a separation column to hold 4 g of silica gel. On top of the silica gel, 5 mm of sodium sulfate is added, and the column is pre-wet with 15 ml of hexane. p,p'-DDE must be calculated in this method before conversion through the use of chromic acid. The solution containing the PCB's and DDT is poured into a 125 ml separator along with an eluate of either hexane or petroleum ether. Add 5 ml of chromic acid reagent, then shake separator 2 min for each microgram of p,p'-DDE in the separator. The chromic acid reagent is prepared by dissolving 10 g of chromic acid in 6 ml of water with heat, then adding 120 ml of glacial acetic acid after cooling. The hexane containing the converted p,p'-DDE is transfered to the silica gel column. A 250 ml K-D equipped with a 5 ml tip is placed under the colunm to receive the various fractions. Each time a fraction is eluted, another K-D similarly equipped is placed beneath the column. The eluates are evaporated to the desired volume for injection on a GLC. PCB's will appear in the first fraction, and DDT and its analogs will appear in the second and third fractions.","Separation of polychlorinated biphenyls from DDT and its analogs using chromic acid and silica gel Abs: PESTAB. A method to separate and determine polychlorinated biphenyls (PCB's) in the presence of DDT and its analogs is described. A glass wool plug is placed in the bottom of a separation column to hold 4 g of silica gel. On top of the silica gel, 5 mm of sodium sulfate is added, and the column is pre-wet with 15 ml of hexane. p,p'-DDE must be calculated in this method before conversion through the use of chromic acid. The solution containing the PCB's and DDT is poured into a 125 ml separator along with an eluate of either hexane or petroleum ether. Add 5 ml of chromic acid reagent, then shake separator 2 min for each microgram of p,p'-DDE in the separator. The chromic acid reagent is prepared by dissolving 10 g of chromic acid in 6 ml of water with heat, then adding 120 ml of glacial acetic acid after cooling. The hexane containing the converted p,p'-DDE is transfered to the silica gel column. A 250 ml K-D equipped with a 5 ml tip is placed under the colunm to receive the various fractions. Each time a fraction is eluted, another K-D similarly equipped is placed beneath the column. The eluates are evaporated to the desired volume for injection on a GLC. PCB's will appear in the first fraction, and DDT and its analogs will appear in the second and third fractions."
1231074,Pedersen and  Mørch 1979,[Peroral chromic acid poisoning treated with emergency hemodialysis],,[Peroral chromic acid poisoning treated with emergency hemodialysis] Abs: 
1231073,Berkowitz and  Travis 1979,An electron microscope comparison of plasma membrane vesicles from meristematic and mature soybean root tissue,"Plasma membrane vesicles were isolated from homogenates of meristematic and mature soybean root tissue by differential sucrose gradient centrifugation. Vesicles were positively identified by the phosphotungstic acid-chromic acid procedure (PACP). The two preparations were comparable in size class distribution, mitochondrial contamination, and per cent plasma membrane vesicles present. Purity levels were estimated to be greater than 75%. The specificity of PACP was observed for a variety of cell types from both regions. Some variability in PACP staining was offset by careful modulation of the stain protocol and was found to be independent of developmental stage in subcellular fractions. Patchy or discontinuous staining, observed in both intact tissue and in subcellular fractions from both regions, was found to be a function of stain time.","An electron microscope comparison of plasma membrane vesicles from meristematic and mature soybean root tissue Abs: Plasma membrane vesicles were isolated from homogenates of meristematic and mature soybean root tissue by differential sucrose gradient centrifugation. Vesicles were positively identified by the phosphotungstic acid-chromic acid procedure (PACP). The two preparations were comparable in size class distribution, mitochondrial contamination, and per cent plasma membrane vesicles present. Purity levels were estimated to be greater than 75%. The specificity of PACP was observed for a variety of cell types from both regions. Some variability in PACP staining was offset by careful modulation of the stain protocol and was found to be independent of developmental stage in subcellular fractions. Patchy or discontinuous staining, observed in both intact tissue and in subcellular fractions from both regions, was found to be a function of stain time."
1231072,Rager et al. 1979,An improved silver stain for developing nervous tissue,"A reduced silver technique using physical development to stain embryonic nervous tissue is described. Brains are fixed in Bodian's fixative. Paraffin sections are pretreated with 1% chromic acid or 5% formol. They are impregnated with 0.01% silver nitrate dissolved in 0.1 M boric acid/sodium tetraborate buffer of pH 8 or with silver proteinate. Finally they are developed in a special physical developer which contains 0.1% silver nitrate, 0.01-0.1% formol as reducing agent, 2.5% sodium carbonate to buffer the solution at pH 10.3, 0.1% ammonium nitrate to prevent precipitation of silver hydroxide, and 5% tungstosilicic acid as a protective colloid. The development takes several minutes in this solution, thus the intensity of staining can be controlled easily. The method yields uniform, complete and reproducible staining of axons at all developmental stages of the nervous tissue and is easy to handle.","An improved silver stain for developing nervous tissue Abs: A reduced silver technique using physical development to stain embryonic nervous tissue is described. Brains are fixed in Bodian's fixative. Paraffin sections are pretreated with 1% chromic acid or 5% formol. They are impregnated with 0.01% silver nitrate dissolved in 0.1 M boric acid/sodium tetraborate buffer of pH 8 or with silver proteinate. Finally they are developed in a special physical developer which contains 0.1% silver nitrate, 0.01-0.1% formol as reducing agent, 2.5% sodium carbonate to buffer the solution at pH 10.3, 0.1% ammonium nitrate to prevent precipitation of silver hydroxide, and 5% tungstosilicic acid as a protective colloid. The development takes several minutes in this solution, thus the intensity of staining can be controlled easily. The method yields uniform, complete and reproducible staining of axons at all developmental stages of the nervous tissue and is easy to handle."
1231068,Dalager et al. 1980,Cancer mortality among workers exposed to zinc chromate paints,"To evaluate the carcinogenicity of chromium compounds among user industries, the proportionate mortality experience of spray painters exposed to zinc chromate primer paints and electroplaters exposed to chromic acid in the aircraft maintenance industry was examined. Compared to the mortality patterns of U.S. white males, no excess of cancer was found in the 48 deaths among electroplaters. Analysis of the 202 deaths among spray painters revealed a significant excess of cancer, primarily of the respiratory tract. The relative increase of respiratory cancer showed a positive gradient with the length of estimated exposure time, and was confined to painters whose interval from first employment to death was at least 20 years. The findings consistent with occupational exposure to chromium compounds, previously shown to be carcinogenic in manufacturing processes, but the effect of other paint constituents, tobacco smoking, or methodologic limitations could not be discounted.","Cancer mortality among workers exposed to zinc chromate paints Abs: To evaluate the carcinogenicity of chromium compounds among user industries, the proportionate mortality experience of spray painters exposed to zinc chromate primer paints and electroplaters exposed to chromic acid in the aircraft maintenance industry was examined. Compared to the mortality patterns of U.S. white males, no excess of cancer was found in the 48 deaths among electroplaters. Analysis of the 202 deaths among spray painters revealed a significant excess of cancer, primarily of the respiratory tract. The relative increase of respiratory cancer showed a positive gradient with the length of estimated exposure time, and was confined to painters whose interval from first employment to death was at least 20 years. The findings consistent with occupational exposure to chromium compounds, previously shown to be carcinogenic in manufacturing processes, but the effect of other paint constituents, tobacco smoking, or methodologic limitations could not be discounted."
1231067,Michaels 1980,Alterations in the distribution of glycoproteins in epithelial cells of murine colon after injection of tunicamycin,"Glycoproteins are associated with several structures of colonic absorptive cells of the mouse. These include the cell coat, Golgi apparatus and vesicles that transport the glycoproteins from the apparatus to the cell surface (Michaels and Leblond 1976). In many in vitro systems, the antibiotic tunicamycin inhibits the glycosylation of asparagine residues yielding carbohydrate-poor glycoproteins. In the present in vivo study, tunicamycin was injected into mice. The murine colonic epithelial cells were prepared routinely for electron microscopy and cytochemistry. Cells from the experimental and control animals were similar morphologically. However, staining by the periodic acid-chromic acid-silver methenamine technique, revealed differences in the distribution of glycoproteins. In animals that received the higher dosages of tunicamycin there was a substantial reduction in silver staining in both the Golgi apparatus and the vesicles of colonic epithelial cells compared to these structures in cells of identically treated control tissues, whereas the staining over the cell coat was not significantly altered. Possible explanations for the staining of the cell coat in the treated animals were provided in the text. This report demonstrates the feasibility of using tunicamycin in vivo and detection of the change obtained by the silver methenamine method.","Alterations in the distribution of glycoproteins in epithelial cells of murine colon after injection of tunicamycin Abs: Glycoproteins are associated with several structures of colonic absorptive cells of the mouse. These include the cell coat, Golgi apparatus and vesicles that transport the glycoproteins from the apparatus to the cell surface (Michaels and Leblond 1976). In many in vitro systems, the antibiotic tunicamycin inhibits the glycosylation of asparagine residues yielding carbohydrate-poor glycoproteins. In the present in vivo study, tunicamycin was injected into mice. The murine colonic epithelial cells were prepared routinely for electron microscopy and cytochemistry. Cells from the experimental and control animals were similar morphologically. However, staining by the periodic acid-chromic acid-silver methenamine technique, revealed differences in the distribution of glycoproteins. In animals that received the higher dosages of tunicamycin there was a substantial reduction in silver staining in both the Golgi apparatus and the vesicles of colonic epithelial cells compared to these structures in cells of identically treated control tissues, whereas the staining over the cell coat was not significantly altered. Possible explanations for the staining of the cell coat in the treated animals were provided in the text. This report demonstrates the feasibility of using tunicamycin in vivo and detection of the change obtained by the silver methenamine method."
1231065,Stratton et al. 1980,The ultrastructural histochemistry and stereoscanning electron microscopy of the rodent and amphibian surfactant systems,"Ultrastructural histochemical precedures were employed to determine the carbohydrate components and their contributions to the rodent and amphibian surfactant systems. Zirconium stained the rodent (rat) cytoplasm surrounding the multilamellar bodies, the Golgi, and was associated with the membrane structures of the compact lamellae of alveolar multilamellar bodies. In the rodent and amphibian (Rana pipiens), ruthenium red stain was observed within all tubular myelin surfactant matricies. The &quot;gutters,&quot; tubular myelin surfactant matrix, and intratubular myelin surfactant matrix materials all demonstrated a positive reaction product. The periodic acid-chromic acid-silver procedure revealed irregular channels extending from the multilamellar bodies to the surface of the rodent great alveolar pneumocyte. The extra-pulmonary and respiratory surfaces in both species were additionally studied by stereoscanning electron microscopy. The respiratory anatomy of the rodent was corroborated. The amphibian lung demonstrated three orders of septa, and in the expired state, tertiary septal pits. The amphibian primary septa were hollow, blind tubules containing respiratory surfaces.","The ultrastructural histochemistry and stereoscanning electron microscopy of the rodent and amphibian surfactant systems Abs: Ultrastructural histochemical precedures were employed to determine the carbohydrate components and their contributions to the rodent and amphibian surfactant systems. Zirconium stained the rodent (rat) cytoplasm surrounding the multilamellar bodies, the Golgi, and was associated with the membrane structures of the compact lamellae of alveolar multilamellar bodies. In the rodent and amphibian (Rana pipiens), ruthenium red stain was observed within all tubular myelin surfactant matricies. The &quot;gutters,&quot; tubular myelin surfactant matrix, and intratubular myelin surfactant matrix materials all demonstrated a positive reaction product. The periodic acid-chromic acid-silver procedure revealed irregular channels extending from the multilamellar bodies to the surface of the rodent great alveolar pneumocyte. The extra-pulmonary and respiratory surfaces in both species were additionally studied by stereoscanning electron microscopy. The respiratory anatomy of the rodent was corroborated. The amphibian lung demonstrated three orders of septa, and in the expired state, tertiary septal pits. The amphibian primary septa were hollow, blind tubules containing respiratory surfaces."
1231064,Travis and  Berkowitz 1980,Characterization of Soybean Plasma Membrane during Development: FREE STEROL COMPOSITION AND CONCANAVALIN A BINDING STUDIES,"PLASMA MEMBRANE PREPARATIONS FROM SOYBEAN ROOT AND HYPOCOTYL CONTAINED THE FOLLOWING FREE STEROLS: cholesterol, campesterol, stigmasterol, and sitosterol. The cholesterol level was relatively low in root plasma membrane (less than 0.5%) but was 1.4 to 2.4% in hypocotyl membrane. The relative levels of the three other sterols fluctuated with cellular development and tissue source. Campesterol level decreased with the development of both root and hypocotyl membrane. With development, stigmasterol increased greatly in root membrane but remained constant in hypocotyl membrane, and sitosterol, the major free sterol component of all membrane preparations, decreased in root membrane but increased slightly in hypocotyl membrane.Electron microscope studies indicated that all root plasma membrane preparations were equivalent in terms of relative purity. Hypocotyl membrane preparations contained significantly greater levels of contaminating membrane components.Root plasma membrane fractions were between 70 and 80% pure as determined by staining with the phosphotungstic acid-chromic acid procedure (PACP). Staining was most definitive for vesicles present in complete cross-section. Electron micrographs showed that vesicles treated with concanavalin A (Con A)-ferritin were extensively labeled at the outer surface indicating the presence of mannosyl and/or glucosyl residues at the vesicle surface. Densities of ferritin were highest on vesicles present in oblique section. PACP and Con A-ferritin were thus complementary with respect to topological specificity.The percentage of Con A-ferritin-labeled and/or PACP-stained vesicles in plasma membrane root preparations was greater than 80%. Con A did not bind in purified tonoplast preparations, and binding was reduced in regions of low PACP reactivity in a root membrane fraction containing a lowered proportion of plasma membrane. Con A specificity for the plasma membrane in subcellular membrane preparations is discussed.","Characterization of Soybean Plasma Membrane during Development: FREE STEROL COMPOSITION AND CONCANAVALIN A BINDING STUDIES Abs: PLASMA MEMBRANE PREPARATIONS FROM SOYBEAN ROOT AND HYPOCOTYL CONTAINED THE FOLLOWING FREE STEROLS: cholesterol, campesterol, stigmasterol, and sitosterol. The cholesterol level was relatively low in root plasma membrane (less than 0.5%) but was 1.4 to 2.4% in hypocotyl membrane. The relative levels of the three other sterols fluctuated with cellular development and tissue source. Campesterol level decreased with the development of both root and hypocotyl membrane. With development, stigmasterol increased greatly in root membrane but remained constant in hypocotyl membrane, and sitosterol, the major free sterol component of all membrane preparations, decreased in root membrane but increased slightly in hypocotyl membrane.Electron microscope studies indicated that all root plasma membrane preparations were equivalent in terms of relative purity. Hypocotyl membrane preparations contained significantly greater levels of contaminating membrane components.Root plasma membrane fractions were between 70 and 80% pure as determined by staining with the phosphotungstic acid-chromic acid procedure (PACP). Staining was most definitive for vesicles present in complete cross-section. Electron micrographs showed that vesicles treated with concanavalin A (Con A)-ferritin were extensively labeled at the outer surface indicating the presence of mannosyl and/or glucosyl residues at the vesicle surface. Densities of ferritin were highest on vesicles present in oblique section. PACP and Con A-ferritin were thus complementary with respect to topological specificity.The percentage of Con A-ferritin-labeled and/or PACP-stained vesicles in plasma membrane root preparations was greater than 80%. Con A did not bind in purified tonoplast preparations, and binding was reduced in regions of low PACP reactivity in a root membrane fraction containing a lowered proportion of plasma membrane. Con A specificity for the plasma membrane in subcellular membrane preparations is discussed."
1231062,Beaulieu et al. 1980,A comparison of aerosol sampling techniques: &quot;open&quot; versus &quot;closed-face&quot; filter cassettes,"Accepted practice by most professional industrial hygienists in government and industry is to use &quot;closed-face&quot; filter cassette techniques as standard sampling procedures for the majority of aerosols. A two-phase, field study was conducted to determine whether a gravimetric bias exists between &quot;open&quot; and &quot;closed-face&quot; sampling methods. Phase I involved an in-depth analysis of the potential gravimetric viability as it applies to an industrial paint spray mist, and Phase II was a series of pilot studies, of small sample base, to determine if this phenomena exists over a range of aerosol types. Dusts of wood, grain, cellulose, Portland cement and perlite, welding fumes, and chromic acid mist were sampled in Phase II. Paired breathing zone samples, &quot;open&quot; and &quot;closed-face&quot;, 37 mm, 3-piece filter cassettes were utilized in both phases of the study. In both phases of the study, &quot;open-face&quot; concentrations were consistently higher than &quot;closed-face&quot; concentrations, with the exception of cellulose dust. Based on the concentration for both sampling techniques, the data suggests that &quot;closed-face&quot; sampling techniques (4.0 mm inlet diameter) might be size selective against large particles. This could lead to an underestimation of a worker's total aerosol exposure.","A comparison of aerosol sampling techniques: &quot;open&quot; versus &quot;closed-face&quot; filter cassettes Abs: Accepted practice by most professional industrial hygienists in government and industry is to use &quot;closed-face&quot; filter cassette techniques as standard sampling procedures for the majority of aerosols. A two-phase, field study was conducted to determine whether a gravimetric bias exists between &quot;open&quot; and &quot;closed-face&quot; sampling methods. Phase I involved an in-depth analysis of the potential gravimetric viability as it applies to an industrial paint spray mist, and Phase II was a series of pilot studies, of small sample base, to determine if this phenomena exists over a range of aerosol types. Dusts of wood, grain, cellulose, Portland cement and perlite, welding fumes, and chromic acid mist were sampled in Phase II. Paired breathing zone samples, &quot;open&quot; and &quot;closed-face&quot;, 37 mm, 3-piece filter cassettes were utilized in both phases of the study. In both phases of the study, &quot;open-face&quot; concentrations were consistently higher than &quot;closed-face&quot; concentrations, with the exception of cellulose dust. Based on the concentration for both sampling techniques, the data suggests that &quot;closed-face&quot; sampling techniques (4.0 mm inlet diameter) might be size selective against large particles. This could lead to an underestimation of a worker's total aerosol exposure."
1231060,Del Conte 1981,Cell types with secretory granules reactive to silver-methenamine after periodic-chromic oxidation in the anterior hypophysis of a lizard. An electron microscopic study,"The number of cell types that in reptilian pars distalis react with periodic acid-Schiff's leucofuchsin is a controversial question. The problem has been investigated at ultrastructural level in the teiid lizard Cnemidophorus lemniscatus (L) with the periodic acid-chromic acid-silver methenamine technique, which gives comparable results. Reactive cells were correlated with types extensively studied with conventional methods for electron microscopy in diverse experimental conditions. The three secretory cell types that have granules intensely stained by silver are considered to produce glycoprotein hormones. One is constituted of rounded cells with small spherical granules evenly stained; they abound in caudal and ventral regions, and may be assimilated to thyrotrophs. The other two types are assumed to be gonadotrophs. Rostral gonadotrophs are large cells with round granules of very different sizes; polymorphic bodies and the content of dilated endoplasmic reticulum appear slightly stained. Caudal gonadotrophs are elongate cells with small granules of irregular shape, which diversely take silver. A fourth secretory cell type, of rostral localization, has medium-sized rounded granules, uniformly stained but with lesser intensity than those of glycoprotein-producing cells; these elements are considered corticotrophs and often contain few granules. The scanty granules of folliculo-stellate cells, as well as the luminal substance of intercellular canaliculi, are rather strongly reactive; a certain secretory role of these cells is assumed.","Cell types with secretory granules reactive to silver-methenamine after periodic-chromic oxidation in the anterior hypophysis of a lizard. An electron microscopic study Abs: The number of cell types that in reptilian pars distalis react with periodic acid-Schiff's leucofuchsin is a controversial question. The problem has been investigated at ultrastructural level in the teiid lizard Cnemidophorus lemniscatus (L) with the periodic acid-chromic acid-silver methenamine technique, which gives comparable results. Reactive cells were correlated with types extensively studied with conventional methods for electron microscopy in diverse experimental conditions. The three secretory cell types that have granules intensely stained by silver are considered to produce glycoprotein hormones. One is constituted of rounded cells with small spherical granules evenly stained; they abound in caudal and ventral regions, and may be assimilated to thyrotrophs. The other two types are assumed to be gonadotrophs. Rostral gonadotrophs are large cells with round granules of very different sizes; polymorphic bodies and the content of dilated endoplasmic reticulum appear slightly stained. Caudal gonadotrophs are elongate cells with small granules of irregular shape, which diversely take silver. A fourth secretory cell type, of rostral localization, has medium-sized rounded granules, uniformly stained but with lesser intensity than those of glycoprotein-producing cells; these elements are considered corticotrophs and often contain few granules. The scanty granules of folliculo-stellate cells, as well as the luminal substance of intercellular canaliculi, are rather strongly reactive; a certain secretory role of these cells is assumed."
1231058,Graf and  Klessen 1981,Glycogen in pancreatic islets of steroid diabetic rats. Carbohydrate histochemical detection and localization using an immunocytochemical technique,"In the islets of the rat pancreas, steroid diabetes induced by triamcinolon-acetonid leads to degranulation of the B cells and glycogen infiltration. The glycogen cannot be satisfactorily detected using methods like the chromic acid technique according to Bauer, staining with Best's carmine, or the usually applied periodic acid-Schiff (PAS) reaction. Glycogen detection is improved, however, when lead tetraacetate is used in place of periodic acid as oxidizing agent. When combining the carbohydrate detection method with the peroxidase--antiperoxidase (PAP) method used for immunocytochemical detection of the various pancreatic islet hormones, paraffin sections reveal that glycogen is primarily localized in granulated B cells; the degranulated B cells also contain glycogen, though in smaller amounts. In contrast, the islet cells containing somatostatin, glucagon and pancreatic polypeptide are nearly free of glycogen.","Glycogen in pancreatic islets of steroid diabetic rats. Carbohydrate histochemical detection and localization using an immunocytochemical technique Abs: In the islets of the rat pancreas, steroid diabetes induced by triamcinolon-acetonid leads to degranulation of the B cells and glycogen infiltration. The glycogen cannot be satisfactorily detected using methods like the chromic acid technique according to Bauer, staining with Best's carmine, or the usually applied periodic acid-Schiff (PAS) reaction. Glycogen detection is improved, however, when lead tetraacetate is used in place of periodic acid as oxidizing agent. When combining the carbohydrate detection method with the peroxidase--antiperoxidase (PAP) method used for immunocytochemical detection of the various pancreatic islet hormones, paraffin sections reveal that glycogen is primarily localized in granulated B cells; the degranulated B cells also contain glycogen, though in smaller amounts. In contrast, the islet cells containing somatostatin, glucagon and pancreatic polypeptide are nearly free of glycogen."
1231057,Bowes et al. 1981,Ultrastructural localisation of lactoferrin and glycoprotein in human bronchial glands,"The distribution of lactoferrin and glycoprotein in human bronchial glands has been studied by electron microscopy using an immunoperoxidase method to stain the former and a periodic acid-chromic acid-silver methenamine sequence for the latter, each applied to ultrathin Epon sections. The distribution of lactoferrin corresponds to that of lysozyme. Lactoferrin and lysozyme are both confined to serous acini where the granules show a variable pattern of staining. Some serous granules are filled uniformly with lactoferrin, some lack lactoferrin in a small central core or a thin peripheral rim, and some are completely devoid of lactoferrin. Glycoprotein is present in all mucous granules but only certain serous granules. The latter may be filled uniformly with glycoprotein or glycoprotein may form a thin peripheral coat about centrally located lactoferrin and lysozyme. An electron-dense central core found in some serous granules contains neither glycoprotein, lactoferrin, nor lysozyme.","Ultrastructural localisation of lactoferrin and glycoprotein in human bronchial glands Abs: The distribution of lactoferrin and glycoprotein in human bronchial glands has been studied by electron microscopy using an immunoperoxidase method to stain the former and a periodic acid-chromic acid-silver methenamine sequence for the latter, each applied to ultrathin Epon sections. The distribution of lactoferrin corresponds to that of lysozyme. Lactoferrin and lysozyme are both confined to serous acini where the granules show a variable pattern of staining. Some serous granules are filled uniformly with lactoferrin, some lack lactoferrin in a small central core or a thin peripheral rim, and some are completely devoid of lactoferrin. Glycoprotein is present in all mucous granules but only certain serous granules. The latter may be filled uniformly with glycoprotein or glycoprotein may form a thin peripheral coat about centrally located lactoferrin and lysozyme. An electron-dense central core found in some serous granules contains neither glycoprotein, lactoferrin, nor lysozyme."
1231055,Mollenhauer and  Morré 1981,Selective staining of dictyosome-like structures (DLS) from spermatocytes of the guinea pig using phosphotungstic acid at low pH,"Dictyosome-like structures (DLS) occur abundantly in primary spermatocytes of the guinea pig. DLS superficially resemble dictyosomes of Golgi apparatus in that they consist of stacked cisternae and react similarly to some cytochemical markers. DLS saccules are also present in residual bodies and in the cytoplasmic droplet of the sperm, but the stacked configuration (or dictyosome form) is seldom present at these stages of development. A mixture of 1% phosphotungstic acid in 10% chromic acid selectively stains the DLS and DLS saccules of guinea pig germ cells. The thick cisternae of spermatid Golgi apparatus and the sperm plasma membrane also stain, but endoplasmic reticulum and the parts of the Golgi apparatus other than the thick cisternae do not stain. The specificity of the stain is retained in crude homogenates as well as in purified cell fractions and may be helpful in identification of DLS in cell fractionation studies. Additionally, the information obtained provides clues to the origin and fate of DLS in the developing mammalian germ cells.","Selective staining of dictyosome-like structures (DLS) from spermatocytes of the guinea pig using phosphotungstic acid at low pH Abs: Dictyosome-like structures (DLS) occur abundantly in primary spermatocytes of the guinea pig. DLS superficially resemble dictyosomes of Golgi apparatus in that they consist of stacked cisternae and react similarly to some cytochemical markers. DLS saccules are also present in residual bodies and in the cytoplasmic droplet of the sperm, but the stacked configuration (or dictyosome form) is seldom present at these stages of development. A mixture of 1% phosphotungstic acid in 10% chromic acid selectively stains the DLS and DLS saccules of guinea pig germ cells. The thick cisternae of spermatid Golgi apparatus and the sperm plasma membrane also stain, but endoplasmic reticulum and the parts of the Golgi apparatus other than the thick cisternae do not stain. The specificity of the stain is retained in crude homogenates as well as in purified cell fractions and may be helpful in identification of DLS in cell fractionation studies. Additionally, the information obtained provides clues to the origin and fate of DLS in the developing mammalian germ cells."
1231053,Nile 1981,Safety. Chromic acid mist: is enough guidance given?--1,,Safety. Chromic acid mist: is enough guidance given?--1 Abs: 
1231052,Nie 1982,Safety. Chromic acid mist: is enough guidance given?--2,,Safety. Chromic acid mist: is enough guidance given?--2 Abs: 
1231049,Schiffl et al. 1982,Dialysis treatment of acute chromium intoxication and comparative efficacy of peritoneal versus hemodialysis in chromium removal,"External burns with chromic acid have been fatal even in cases with corrosions covering less than 10% of the body surface area. We observed a 19-year-old man with third-degree burns and chromium intoxication following accidental contact of both legs with chromium acid solution. The initial course was characterized by serum chromium levels known to be usually lethal (220 micrograms/100 ml), complete anuria, hepatic damage and progressive anemia. Aggressive peritoneal dialysis with a total duration of 252 h between the 4th and 22nd day after exposure caused a progressive decrease in serum chromium levels and resulted in a complete recovery after 35 days. The comparative efficacy of peritoneal versus hemodialysis in chromium removal was evaluated in 5 patients with acute renal failure who were treated with peritoneal dialysis and in 6 patients with end-stage renal failure who underwent hemodialysis. Following intravenous injection of 500 muCi51CrCl3 chromium clearance averaged 0.8 +/- 0.3 ml/min and 2.5 +/- 0.8 ml/min during peritoneal dialysis (n = 50) or hemodialysis (n = 24), respectively. It is concluded that hemodialysis is about 3 times as effective as peritoneal dialysis in chromium removal per unit of time. However, the possibility of applying uninterrupted peritoneal dialysis during the first few days suggests that this method is at least equivalent to hemodialysis for treatment in the initial stage of chromium intoxication.","Dialysis treatment of acute chromium intoxication and comparative efficacy of peritoneal versus hemodialysis in chromium removal Abs: External burns with chromic acid have been fatal even in cases with corrosions covering less than 10% of the body surface area. We observed a 19-year-old man with third-degree burns and chromium intoxication following accidental contact of both legs with chromium acid solution. The initial course was characterized by serum chromium levels known to be usually lethal (220 micrograms/100 ml), complete anuria, hepatic damage and progressive anemia. Aggressive peritoneal dialysis with a total duration of 252 h between the 4th and 22nd day after exposure caused a progressive decrease in serum chromium levels and resulted in a complete recovery after 35 days. The comparative efficacy of peritoneal versus hemodialysis in chromium removal was evaluated in 5 patients with acute renal failure who were treated with peritoneal dialysis and in 6 patients with end-stage renal failure who underwent hemodialysis. Following intravenous injection of 500 muCi51CrCl3 chromium clearance averaged 0.8 +/- 0.3 ml/min and 2.5 +/- 0.8 ml/min during peritoneal dialysis (n = 50) or hemodialysis (n = 24), respectively. It is concluded that hemodialysis is about 3 times as effective as peritoneal dialysis in chromium removal per unit of time. However, the possibility of applying uninterrupted peritoneal dialysis during the first few days suggests that this method is at least equivalent to hemodialysis for treatment in the initial stage of chromium intoxication."
1231048,Kang et al. 1982,Correlation between growth rate and cytochemistry in Morris hepatomas,"The correlation between the cytochemistry (glycoprotein, glycogen, glucose-6-phosphatase, catalase, alkaline phosphatase) and the growth rate of the fast-growing Morris hepatoma 3924A and the slow-growing Morris hepatoma 9618A was studied by utracytochemical techniques. By the chromic acid-phosphotungstic acid technique, acid glycoprotein is stained in glycocalyx, Golgi saccules and vesicles, and secretory granules of the tumor cells of both hepatomas. However, the hepatoma 3924A cells contain thicker glycocalyx and more numerous glycoprotein-rich granules than hepatoma 9618A cells. Abundant alpha and beta glycogen particles are found in hepatoma 3924A. Moderate glucose-6-phosphatase activity is observed in the cisternae of endoplasmic reticulum and nuclear envelope of hepatoma 9618A, but it is totally absent in hepatoma 3924A. High catalase activity is present in numerous peroxisomes of hepatoma 9618A. Hepatoma 3924A contains only a few catalase-positive microperoxisomes. Weak to moderate alkaline phosphatase is present in the plasma membrane and nuclear envelope of hepatoma 9618A cells, while hepatoma 3924A shows no activity of the enzyme. All the cytochemical parameters except glycoprotein show an inverse relationship with the growth rate of the hepatomas. The higher intracellular glycoprotein content of hepatoma 3924A may be related to differences in cell coat secretion (composition and activity) from the slower-growing hepatoma 9618A","Correlation between growth rate and cytochemistry in Morris hepatomas Abs: The correlation between the cytochemistry (glycoprotein, glycogen, glucose-6-phosphatase, catalase, alkaline phosphatase) and the growth rate of the fast-growing Morris hepatoma 3924A and the slow-growing Morris hepatoma 9618A was studied by utracytochemical techniques. By the chromic acid-phosphotungstic acid technique, acid glycoprotein is stained in glycocalyx, Golgi saccules and vesicles, and secretory granules of the tumor cells of both hepatomas. However, the hepatoma 3924A cells contain thicker glycocalyx and more numerous glycoprotein-rich granules than hepatoma 9618A cells. Abundant alpha and beta glycogen particles are found in hepatoma 3924A. Moderate glucose-6-phosphatase activity is observed in the cisternae of endoplasmic reticulum and nuclear envelope of hepatoma 9618A, but it is totally absent in hepatoma 3924A. High catalase activity is present in numerous peroxisomes of hepatoma 9618A. Hepatoma 3924A contains only a few catalase-positive microperoxisomes. Weak to moderate alkaline phosphatase is present in the plasma membrane and nuclear envelope of hepatoma 9618A cells, while hepatoma 3924A shows no activity of the enzyme. All the cytochemical parameters except glycoprotein show an inverse relationship with the growth rate of the hepatomas. The higher intracellular glycoprotein content of hepatoma 3924A may be related to differences in cell coat secretion (composition and activity) from the slower-growing hepatoma 9618A"
1231047,Fregert 1982,Rhinorrhea due to chromic acid etching in a chromium sensitive person,HEEP COPYRIGHT: BIOL ABS. NOTE ALLERGY DERMATITIS MASON,Rhinorrhea due to chromic acid etching in a chromium sensitive person Abs: HEEP COPYRIGHT: BIOL ABS. NOTE ALLERGY DERMATITIS MASON
1231045,Tanaka and  Hirata 1982,Ascospore development in the fission yeasts Schizosaccharomyces pombe and S. japonicus,"The fine structure of ascospore formation in the fission yeasts Schizosaccharomyces pombe and Schizosaccharomyces japonicus var. japonicus was studied by serial thin-sectioning and electron microscopy. The morphogenetic events were almost the same in both species. Ascospore development was initiated by the formation of the forespore membrane on the cytoplasmic side of the differentiated nucleus-associated organelle (NAO) in the interval between meiosis I and II in S. pombe, or during the post-meiotic nuclear division in S. japonicus, and the process proceeded almost synchronously through the two or four nuclei in the ascus. The forespore membrane developed by fusion of the cytoplasmic vesicles and this was clearly demonstrated in S. japonicus where the behaviour of vesicles involved in the forespore membrane development could be traced as they were marked by the presence of electron-dense granules. The staining technique, by phosphotungustic acid--chromic acid (PTA-CA) after treatment with periodic acid, was used to attempt to elucidate the origin and the nature of the forespore membrane. The method specific to plasmalemma-type membranes stained both ascus and ascospore plasmalemmas; the forespore membrane was not stained at first but developed the same affinity for stain as the plasma membrane in the course of ascospore development. The results suggest that the forespore membrane did not come directly from the ascus plasma membrane, but from another membrane system such as the endoplasmic reticulum. Spore wall material was deposited in the space between the inner and outer leaflets of the forespore membrane.","Ascospore development in the fission yeasts Schizosaccharomyces pombe and S. japonicus Abs: The fine structure of ascospore formation in the fission yeasts Schizosaccharomyces pombe and Schizosaccharomyces japonicus var. japonicus was studied by serial thin-sectioning and electron microscopy. The morphogenetic events were almost the same in both species. Ascospore development was initiated by the formation of the forespore membrane on the cytoplasmic side of the differentiated nucleus-associated organelle (NAO) in the interval between meiosis I and II in S. pombe, or during the post-meiotic nuclear division in S. japonicus, and the process proceeded almost synchronously through the two or four nuclei in the ascus. The forespore membrane developed by fusion of the cytoplasmic vesicles and this was clearly demonstrated in S. japonicus where the behaviour of vesicles involved in the forespore membrane development could be traced as they were marked by the presence of electron-dense granules. The staining technique, by phosphotungustic acid--chromic acid (PTA-CA) after treatment with periodic acid, was used to attempt to elucidate the origin and the nature of the forespore membrane. The method specific to plasmalemma-type membranes stained both ascus and ascospore plasmalemmas; the forespore membrane was not stained at first but developed the same affinity for stain as the plasma membrane in the course of ascospore development. The results suggest that the forespore membrane did not come directly from the ascus plasma membrane, but from another membrane system such as the endoplasmic reticulum. Spore wall material was deposited in the space between the inner and outer leaflets of the forespore membrane."
1231043,Platt-Aloia and  Thomson 1982,Freeze fracture of intact plant tissues,"A procedure for dissolving and handling replicas of cutinized leaves and other plant tissues is described. This technique yields comparatively large replicas which can include vascular tissue, epidermal cells and the cuticle. Dissolution of the tissue involves the sequential use of alcoholic KOH, sulfuric acid and chromic acid. The use of clean, uncoated grids for transfer of the tissue and replicas results in rapid, easy handling with a minimum of breakage or loss. The procedure is more efficient than previous methods and produces large replicas. This allows tissue orientation and more positive identification of cell types for better correlation of freeze fracture results with thin sections of similar material.","Freeze fracture of intact plant tissues Abs: A procedure for dissolving and handling replicas of cutinized leaves and other plant tissues is described. This technique yields comparatively large replicas which can include vascular tissue, epidermal cells and the cuticle. Dissolution of the tissue involves the sequential use of alcoholic KOH, sulfuric acid and chromic acid. The use of clean, uncoated grids for transfer of the tissue and replicas results in rapid, easy handling with a minimum of breakage or loss. The procedure is more efficient than previous methods and produces large replicas. This allows tissue orientation and more positive identification of cell types for better correlation of freeze fracture results with thin sections of similar material."
1231042,Aldrich and  Reiskind 1982,Membrane histochemistry of Physarum polycephalum myxamoebae,"Myxamoebae of Physarum polycephalum are the uninucleate, haploid stage of the organism. Histochemical studies were undertaken to characterize intracellular and plasma membranes, and to provide a basis for assaying subcellular fractions for enrichment in plasma membranes. Lead salts deposition techniques were employed for hydrolytic enzymes. Alcian blue-ruthenium red, osmium tetroxide-potassium ferrocyanide, and phosphotungstic acid-chromic acid stains were evaluated for specificity for plasma membranes. Glucose 6-phosphatase was localized in endoplasmic reticulum, Golgi apparatus, and perinuclear space. 5'-Nucleotidase was localized in food vacuoles, chromatin, and plasmalemma. Acid phosphatase was in food vacuoles and Golgi apparatus. Alkaline phosphatase was in food vacuoles and endoplasmic reticulum. We conclude that none of the above enzymes is suitable as a cytochemical marker for plasma membranes of Physarum myxamoebae, but recommend instead staining ultrathin sections of membrane pellets with phosphotungstic acid-chromic acid, which stains plasma membranes selectively.","Membrane histochemistry of Physarum polycephalum myxamoebae Abs: Myxamoebae of Physarum polycephalum are the uninucleate, haploid stage of the organism. Histochemical studies were undertaken to characterize intracellular and plasma membranes, and to provide a basis for assaying subcellular fractions for enrichment in plasma membranes. Lead salts deposition techniques were employed for hydrolytic enzymes. Alcian blue-ruthenium red, osmium tetroxide-potassium ferrocyanide, and phosphotungstic acid-chromic acid stains were evaluated for specificity for plasma membranes. Glucose 6-phosphatase was localized in endoplasmic reticulum, Golgi apparatus, and perinuclear space. 5'-Nucleotidase was localized in food vacuoles, chromatin, and plasmalemma. Acid phosphatase was in food vacuoles and Golgi apparatus. Alkaline phosphatase was in food vacuoles and endoplasmic reticulum. We conclude that none of the above enzymes is suitable as a cytochemical marker for plasma membranes of Physarum myxamoebae, but recommend instead staining ultrathin sections of membrane pellets with phosphotungstic acid-chromic acid, which stains plasma membranes selectively."
1231040,Michaels 1983,The effects of colchicine on the distribution of glycoprotein-containing vesicles in epithelial cells of the murine colon,"In murine colonic epithelial cells, cell-coat glycoproteins are transported to the cell surface in vesicles that originate at the Golgi apparatus. To determine the role of microtubules in the movement of these vesicles the antimicrotubule agent colchicine was injected into mice at several time intervals prior to sacrifice. In the mice that were treated with colchicine for 4.5 h it was observed that the polarity of the cells was disturbed. The Golgi apparatus and nucleus often appeared interchanged in their positions. The glycoprotein-containing vesicles, normally located apically, were sparse in that location, but abundant near the lateral plasma membranes of the cells at the level of the nucleus and Golgi apparatus. Straining by the periodic acid-chromic acid-silver methenamine technique for glycoproteins clearly revealed the reduction of vesicles apically and accumulation of vesicles laterally. The mechanism responsible for the movement of the vesicles to this location is unclear. It is suggested that the accumulation of vesicles in the lateral region may reflect some hindrance in the fusion of the vesicles with the lateral cell membranes.","The effects of colchicine on the distribution of glycoprotein-containing vesicles in epithelial cells of the murine colon Abs: In murine colonic epithelial cells, cell-coat glycoproteins are transported to the cell surface in vesicles that originate at the Golgi apparatus. To determine the role of microtubules in the movement of these vesicles the antimicrotubule agent colchicine was injected into mice at several time intervals prior to sacrifice. In the mice that were treated with colchicine for 4.5 h it was observed that the polarity of the cells was disturbed. The Golgi apparatus and nucleus often appeared interchanged in their positions. The glycoprotein-containing vesicles, normally located apically, were sparse in that location, but abundant near the lateral plasma membranes of the cells at the level of the nucleus and Golgi apparatus. Straining by the periodic acid-chromic acid-silver methenamine technique for glycoproteins clearly revealed the reduction of vesicles apically and accumulation of vesicles laterally. The mechanism responsible for the movement of the vesicles to this location is unclear. It is suggested that the accumulation of vesicles in the lateral region may reflect some hindrance in the fusion of the vesicles with the lateral cell membranes."
1231039,Goldberg et al. 1983,Lipids in the developing enamel of the rat incisor. Parallel histochemical and biochemical investigations,"Morphologic examination of the developing enamel of rat incisors showed the presence of cell processes and remnants. Histochemical investigation of rapid-frozen freeze-substituted samples, using p-phenylenediamine or a phosphotungstic acid chromic acid mixture, revealed osmiophilic components which were extractable in chloroform-methanol solution and were located inside the tubule-like structures of the extracellular matrix. The presecretory cell-rich and developing enamel zones underwent quantitative and qualitative lipid analysis. Comparison of the biochemical data as well as of the morphological observations, suggests a cellular origin for enamel lipids randomly adsorbed by extracellular matrix components during enamel processing. The nature of the material which appeared as an osmiophilic intra-tubular filling is still unresolved.","Lipids in the developing enamel of the rat incisor. Parallel histochemical and biochemical investigations Abs: Morphologic examination of the developing enamel of rat incisors showed the presence of cell processes and remnants. Histochemical investigation of rapid-frozen freeze-substituted samples, using p-phenylenediamine or a phosphotungstic acid chromic acid mixture, revealed osmiophilic components which were extractable in chloroform-methanol solution and were located inside the tubule-like structures of the extracellular matrix. The presecretory cell-rich and developing enamel zones underwent quantitative and qualitative lipid analysis. Comparison of the biochemical data as well as of the morphological observations, suggests a cellular origin for enamel lipids randomly adsorbed by extracellular matrix components during enamel processing. The nature of the material which appeared as an osmiophilic intra-tubular filling is still unresolved."
1231037,Yoshida et al. 1983,Partition of membrane particles in aqueous two-polymer phase system and its practical use for purification of plasma membranes from plants,"A simplified method for the isolation of a plasma membrane-enriched fraction from plants utilizing an aqueous two-polymer phase system is outlined. Mainly, the plant used was Orchard grass (Dactylis glomerata L.). The two-phase system consisted of 5.6% (w/w) of dextran T500 and 5.6% (w/w) of polyethyleneglycol 4000 in 0.5 molar sorbitol-15 millimolar Tris-maleate (pH 7.3), and 30 millimolar NaCl. In this system, the plasma membranes and the other membranes were preferentially partitioned into the top phase and into the lower phase, respectively. The purity of the isolated plasma membrane was sufficiently high even after a single partition (i.e. about 85% purity) and more than 90% purity was obtained after repeating the partition in a newly prepared lower phase. The plasma membrane was identified with the aid of phosphotungstic acid-chromic acid stain and the association of vanadate-sensitive Mg(2+)-ATPase. The plasma membrane-associated ATPase had a pH optimum at 6.5 and showed a high specificity for Mg(2+) and ATP. KCl stimulation was low (6% stimulation) at the pH optimum, but a relatively high stimulation (23%) occurred at pH 5.5. This method for plasma membrane isolation may be applicable to a wide variety of plants and plant tissue including green leaves.","Partition of membrane particles in aqueous two-polymer phase system and its practical use for purification of plasma membranes from plants Abs: A simplified method for the isolation of a plasma membrane-enriched fraction from plants utilizing an aqueous two-polymer phase system is outlined. Mainly, the plant used was Orchard grass (Dactylis glomerata L.). The two-phase system consisted of 5.6% (w/w) of dextran T500 and 5.6% (w/w) of polyethyleneglycol 4000 in 0.5 molar sorbitol-15 millimolar Tris-maleate (pH 7.3), and 30 millimolar NaCl. In this system, the plasma membranes and the other membranes were preferentially partitioned into the top phase and into the lower phase, respectively. The purity of the isolated plasma membrane was sufficiently high even after a single partition (i.e. about 85% purity) and more than 90% purity was obtained after repeating the partition in a newly prepared lower phase. The plasma membrane was identified with the aid of phosphotungstic acid-chromic acid stain and the association of vanadate-sensitive Mg(2+)-ATPase. The plasma membrane-associated ATPase had a pH optimum at 6.5 and showed a high specificity for Mg(2+) and ATP. KCl stimulation was low (6% stimulation) at the pH optimum, but a relatively high stimulation (23%) occurred at pH 5.5. This method for plasma membrane isolation may be applicable to a wide variety of plants and plant tissue including green leaves."
1231036,Franchini et al. 1983,Mortality experience among chromeplating workers. Initial findings,"A retrospective cohort study was conducted in nine chromeplating plants to examine the mortality of workers employed for at least one year during the period January 1951-December 1981. The study group totaled 178 individuals, 116 of whom were from ""hard"" and 62 from ""bright"" chromeplating plants. Vital status ascertainment was 97% complete. The total number of deaths was fairly close to the expected figure (15 observed, 15.2 expected), whereas deaths from tumors exceeded the expected number (8 observed, 4.2 expected). Individuals were distinguished into two subcohorts depending on the exposure intensity, which was much higher in hard than in bright chromeplating. Most deaths from cancer occurred among hard chromium platers, the excess against the expected rate being statistically significant (7 observed, 2.7 expected, p = 0.02). All deaths from lung cancer occurred in this subcohort (3 observed, 0.7 expected, p = 0.03). The increased mortality from cancer among chromium platers seems to be related to exposure intensity and strongly suggests the need for further studies on larger cohorts to confirm the carcinogenicity of chromic acid in man.","Mortality experience among chromeplating workers. Initial findings Abs: A retrospective cohort study was conducted in nine chromeplating plants to examine the mortality of workers employed for at least one year during the period January 1951-December 1981. The study group totaled 178 individuals, 116 of whom were from ""hard"" and 62 from ""bright"" chromeplating plants. Vital status ascertainment was 97% complete. The total number of deaths was fairly close to the expected figure (15 observed, 15.2 expected), whereas deaths from tumors exceeded the expected number (8 observed, 4.2 expected). Individuals were distinguished into two subcohorts depending on the exposure intensity, which was much higher in hard than in bright chromeplating. Most deaths from cancer occurred among hard chromium platers, the excess against the expected rate being statistically significant (7 observed, 2.7 expected, p = 0.02). All deaths from lung cancer occurred in this subcohort (3 observed, 0.7 expected, p = 0.03). The increased mortality from cancer among chromium platers seems to be related to exposure intensity and strongly suggests the need for further studies on larger cohorts to confirm the carcinogenicity of chromic acid in man."
1231035,Mcclung and  Wood 1983,Ultrastructural differentiation within the central nervous system between indolamines and catecholamines by energy dispersive X-ray analysis following paraformaldehyde pretreatment,"Dense bodies containing high amounts of chrome were localized in the perikarya of substantia nigra and dorsal raphe neurons following the cytochemical reaction of endogenous dopamine and serotonin (respectively) with glutaraldehyde-dichromate (GDC). Energy dispersive X-ray analysis of these bodies revealed chrome levels two to four times higher than those recorded from the cytoplasmic background. Pretreatment with paraformaldehyde blocked the GDC reaction within the dense bodies in the substantia nigra (chrome levels similar to background), while the chrome levels in the dense bodies of the raphe neurons remained elevated. This demonstrates that pretreatment with paraformaldehyde allows selective localization of central nervous system serotonin stores by the GDC technique.","Ultrastructural differentiation within the central nervous system between indolamines and catecholamines by energy dispersive X-ray analysis following paraformaldehyde pretreatment Abs: Dense bodies containing high amounts of chrome were localized in the perikarya of substantia nigra and dorsal raphe neurons following the cytochemical reaction of endogenous dopamine and serotonin (respectively) with glutaraldehyde-dichromate (GDC). Energy dispersive X-ray analysis of these bodies revealed chrome levels two to four times higher than those recorded from the cytoplasmic background. Pretreatment with paraformaldehyde blocked the GDC reaction within the dense bodies in the substantia nigra (chrome levels similar to background), while the chrome levels in the dense bodies of the raphe neurons remained elevated. This demonstrates that pretreatment with paraformaldehyde allows selective localization of central nervous system serotonin stores by the GDC technique."
1231031,Blomquist et al. 1983,Sampling and analysis of hexavalent chromium during exposure to chromic acid mist and welding fumes,"Sampling and analysis of hexavalent chromium during exposure to chromic acid mist and welding fumes. Scand j work environ &amp; health 9 (1983) 489-495. In view of the serious health effects of hexavalent chromium, the problems involved in its sampling and analysis in workroom air have been the subject of much concern. In this paper, the stability problems arising from the reduction of hexavalent to trivalent chromium during sampling, sample storage, and analysis are discussed. Replacement of sulfuric acid by a sodium acetate buffer (pH 4) as a leaching solution prior to analysis with the diphenylcarbazide (DPC) method is suggested and is demonstrated to be necessary in order to avoid reduction. Field samples were taken from two different industrial processes-manual metal arc welding on stainless steel without shield gas and chromium plating. A comparison was made of the DPC method, acidic dissolution with atomic absorption spectrophotometric (AAS) analysis, and the carbonate method. For chromic acid mist, the DPC method and AAS analysis were shown to give the same results. In the analysis of welding fumes, the modified DPC method gave the same results as the laborious and less sensitive carbonate method.","Sampling and analysis of hexavalent chromium during exposure to chromic acid mist and welding fumes Abs: Sampling and analysis of hexavalent chromium during exposure to chromic acid mist and welding fumes. Scand j work environ &amp; health 9 (1983) 489-495. In view of the serious health effects of hexavalent chromium, the problems involved in its sampling and analysis in workroom air have been the subject of much concern. In this paper, the stability problems arising from the reduction of hexavalent to trivalent chromium during sampling, sample storage, and analysis are discussed. Replacement of sulfuric acid by a sodium acetate buffer (pH 4) as a leaching solution prior to analysis with the diphenylcarbazide (DPC) method is suggested and is demonstrated to be necessary in order to avoid reduction. Field samples were taken from two different industrial processes-manual metal arc welding on stainless steel without shield gas and chromium plating. A comparison was made of the DPC method, acidic dissolution with atomic absorption spectrophotometric (AAS) analysis, and the carbonate method. For chromic acid mist, the DPC method and AAS analysis were shown to give the same results. In the analysis of welding fumes, the modified DPC method gave the same results as the laborious and less sensitive carbonate method."
1231028,Laitung and  Earley 1984,The role of surgery in chromic acid burns: our experience with two patients,"Two patients with chromic acid burns are described, one having a 10 per cent body surface area (BSA) burn, the other a 70 per cent BSA burn. Hexavalent chromium, being more mobile physiologically, is more toxic than trivalent chromium. Both, however, are readily absorbed through burned skin, and cause renal failure. For this reason, emergency excision of burned areas has been advocated as first line treatment. However, this is not always feasible as, for instance, when the size of the burn is large, and is of uncertain value when patients are referred late.","The role of surgery in chromic acid burns: our experience with two patients Abs: Two patients with chromic acid burns are described, one having a 10 per cent body surface area (BSA) burn, the other a 70 per cent BSA burn. Hexavalent chromium, being more mobile physiologically, is more toxic than trivalent chromium. Both, however, are readily absorbed through burned skin, and cause renal failure. For this reason, emergency excision of burned areas has been advocated as first line treatment. However, this is not always feasible as, for instance, when the size of the burn is large, and is of uncertain value when patients are referred late."
1231027,Kobayashi et al. 1984,A survival case of acute chromic acid poisoning treated by peritoneal dialysis,,A survival case of acute chromic acid poisoning treated by peritoneal dialysis Abs: 
1231025,Harry et al. 1984,[Acute renal failure following skin burns by chromic acid (chromium VI)],,[Acute renal failure following skin burns by chromic acid (chromium VI)] Abs: 
1231024,Wang et al. 1985,Chromic acid burns and acute chromium poisoning,The problems encountered during the treatment of a patient with burns covering 40 per cent of the body surface caused by hot chromic acid and the resulting chromium poisoning are described. Anuria developed on the second day after injury and the patient died on the sixth day.,Chromic acid burns and acute chromium poisoning Abs: The problems encountered during the treatment of a patient with burns covering 40 per cent of the body surface caused by hot chromic acid and the resulting chromium poisoning are described. Anuria developed on the second day after injury and the patient died on the sixth day.
1231023,Cardell et al. 1985,"SERGE, the subcellular site of initial hepatic glycogen deposition in the rat: a radioautographic and cytochemical study","Hormonal control of hepatic glycogen and blood glucose levels is one of the major homeostatic mechanisms in mammals: glycogen is synthesized when portal glucose concentration is sufficiently elevated and degraded when glucose levels are low. We have studied initial events of hepatic glycogen synthesis by injecting the synthetic glucocorticoid dexamethasone (DEX) into adrenalectomized rats fasted overnight. Hepatic glycogen levels are very low in adrenalectomized rats, and DEX causes rapid deposition of the complex carbohydrate. Investigation of the process of glycogen deposition was performed by light and electron microscopic (EM) radioautography using [3H]galactose as a glycogen precursor. Rats injected with DEX for 2-3 h and [3H]galactose one hour before being killed displayed an increasing number of intensely labeled hepatocytes. EM radioautography revealed silver grains over small (+/- 1 micron) ovoid or round areas of the cytosome that were rich in smooth endoplasmic reticulum (SER) and contained a high concentration of small dense particles. These distinct areas or foci of SER and presumptive glycogen (SERGE) were most numerous during initial periods of glycogen synthesis. After longer exposure to DEX (4-5 h) more typical deposits of cytoplasmic glycogen were evident in the SERGE regions. Several criteria indicated that the SERGE foci contained glycogen or presumptive glycogen: resemblance of the largest dense particles to beta-glycogen particles in EM; association of 3H-carbohydrate with the foci; removal of particles and label with alpha-amylase; and positive reaction with periodic acid-chromic acid-silver methenamine. The concentration of SER in the small foci and the association of newly formed glycogen particles with elements of SER suggest a role for this organelle in the initial synthesis of glycogen.","SERGE, the subcellular site of initial hepatic glycogen deposition in the rat: a radioautographic and cytochemical study Abs: Hormonal control of hepatic glycogen and blood glucose levels is one of the major homeostatic mechanisms in mammals: glycogen is synthesized when portal glucose concentration is sufficiently elevated and degraded when glucose levels are low. We have studied initial events of hepatic glycogen synthesis by injecting the synthetic glucocorticoid dexamethasone (DEX) into adrenalectomized rats fasted overnight. Hepatic glycogen levels are very low in adrenalectomized rats, and DEX causes rapid deposition of the complex carbohydrate. Investigation of the process of glycogen deposition was performed by light and electron microscopic (EM) radioautography using [3H]galactose as a glycogen precursor. Rats injected with DEX for 2-3 h and [3H]galactose one hour before being killed displayed an increasing number of intensely labeled hepatocytes. EM radioautography revealed silver grains over small (+/- 1 micron) ovoid or round areas of the cytosome that were rich in smooth endoplasmic reticulum (SER) and contained a high concentration of small dense particles. These distinct areas or foci of SER and presumptive glycogen (SERGE) were most numerous during initial periods of glycogen synthesis. After longer exposure to DEX (4-5 h) more typical deposits of cytoplasmic glycogen were evident in the SERGE regions. Several criteria indicated that the SERGE foci contained glycogen or presumptive glycogen: resemblance of the largest dense particles to beta-glycogen particles in EM; association of 3H-carbohydrate with the foci; removal of particles and label with alpha-amylase; and positive reaction with periodic acid-chromic acid-silver methenamine. The concentration of SER in the small foci and the association of newly formed glycogen particles with elements of SER suggest a role for this organelle in the initial synthesis of glycogen."
1231022,Harnik et al. 1985,"Synthesis of 19-hydroxyaldosterone and the 3 beta-hydroxy-5-ene analog of aldosterone, active mineralocorticoids","19-Hydroxyaldosterone (20) and the 3 beta-hydroxy-5-ene analog of aldosterone (HAA) (8) were synthesized from 21-acetoxy-4-pregnene-3,20-dion-20-ethylene ketal-18, 11 beta-lactone (2) as follows: the double bond was transposed from the 4,5 to the 5,6-position by enol acetylation to 3, followed by sodium borohydride reduction. Further reduction of the resulting lactone 4a with diisobutylaluminum hydride (DIBAH) furnished the 20-ketal of HAA 6, from which free HAA (8) and the 18,21-anhydro compound 7 were obtained by acid treatment. The [1H]NMR spectrum of 8 in CDCl3 showed it to be a mixture of two isomeric forms. Correlation with the known aldosterone-gamma-etiolactone (10) was established by periodate oxidation of HAA to the corresponding etiolactone 9 followed by chromic acid oxidation. The preparation of 20 was next effected in the following manner: the diacetate 4b was converted into the 6 beta, 19-oxido compound 13b by addition of hypobromous acid followed by the hypoiodite reaction of the bromohydrin 11. Mild saponification of 13b lead to the corresponding diol 13a, and was followed by selective oxidation to the 3-one 14, readily dehydrobrominated to 15a. Reductive ring opening furnished a mixture of the 19,21-diol 16a and its 5-ene isomer 16b, which was directly converted to the diketal 17. Reduction with DIBAH gave the hemiacetal 18, and hydrolysis of the latter 19-hydroxyaldosterone (20) as a water-soluble solid, accompanied by the 18,21-anhydro compound 19. 19-Hydroxyaldosterone exists in CHCl3 and water as a mixture of mainly two isomers. Periodate oxidation furnished the etiolactone 21. Preliminary results indicate that HAA and 19-hydroxyaldosterone are active mineralocorticoids in the Kagawa bioassay and short-circuit current measurements.","Synthesis of 19-hydroxyaldosterone and the 3 beta-hydroxy-5-ene analog of aldosterone, active mineralocorticoids Abs: 19-Hydroxyaldosterone (20) and the 3 beta-hydroxy-5-ene analog of aldosterone (HAA) (8) were synthesized from 21-acetoxy-4-pregnene-3,20-dion-20-ethylene ketal-18, 11 beta-lactone (2) as follows: the double bond was transposed from the 4,5 to the 5,6-position by enol acetylation to 3, followed by sodium borohydride reduction. Further reduction of the resulting lactone 4a with diisobutylaluminum hydride (DIBAH) furnished the 20-ketal of HAA 6, from which free HAA (8) and the 18,21-anhydro compound 7 were obtained by acid treatment. The [1H]NMR spectrum of 8 in CDCl3 showed it to be a mixture of two isomeric forms. Correlation with the known aldosterone-gamma-etiolactone (10) was established by periodate oxidation of HAA to the corresponding etiolactone 9 followed by chromic acid oxidation. The preparation of 20 was next effected in the following manner: the diacetate 4b was converted into the 6 beta, 19-oxido compound 13b by addition of hypobromous acid followed by the hypoiodite reaction of the bromohydrin 11. Mild saponification of 13b lead to the corresponding diol 13a, and was followed by selective oxidation to the 3-one 14, readily dehydrobrominated to 15a. Reductive ring opening furnished a mixture of the 19,21-diol 16a and its 5-ene isomer 16b, which was directly converted to the diketal 17. Reduction with DIBAH gave the hemiacetal 18, and hydrolysis of the latter 19-hydroxyaldosterone (20) as a water-soluble solid, accompanied by the 18,21-anhydro compound 19. 19-Hydroxyaldosterone exists in CHCl3 and water as a mixture of mainly two isomers. Periodate oxidation furnished the etiolactone 21. Preliminary results indicate that HAA and 19-hydroxyaldosterone are active mineralocorticoids in the Kagawa bioassay and short-circuit current measurements."
1231021,AYa et al. 1985,Two synthetic antigens related to Streptococcus pneumoniae type 3 capsular polysaccharide,"The synthesis of the allyl beta-glycosides (8 and 20, respectively) of beta-D-GlcpA-(1----4)-D-Glcp and beta-D-Glcp-(1----3)-D-GlcpA (overlapping disaccharide fragments A and B) in the linear chain of the capsular polysaccharide (S3) from Streptococcus pneumoniae type 3 is described. Oxidation of allyl 2,3,6,2',3',4'-hexa-O-acetyl-beta-cellobioside with chromic acid and saponification of the product gave 8. The synthesis of 20 involved glycosylation of methyl 5-O-acetyl-1,2-O-isopropylidene-alpha-D-glucofuranuronate or its 3-O-trityl derivative and subsequent furanose----pyranose transformation. The derivatives 8 and 20 were each copolymerised with acrylamide. In serological tests (enzyme immunoassay and passive hemagglutination), the resulting antigens exhibited the specificity of S3. It was concluded that fragment A was a much stronger immunodeterminant than fragment B.","Two synthetic antigens related to Streptococcus pneumoniae type 3 capsular polysaccharide Abs: The synthesis of the allyl beta-glycosides (8 and 20, respectively) of beta-D-GlcpA-(1----4)-D-Glcp and beta-D-Glcp-(1----3)-D-GlcpA (overlapping disaccharide fragments A and B) in the linear chain of the capsular polysaccharide (S3) from Streptococcus pneumoniae type 3 is described. Oxidation of allyl 2,3,6,2',3',4'-hexa-O-acetyl-beta-cellobioside with chromic acid and saponification of the product gave 8. The synthesis of 20 involved glycosylation of methyl 5-O-acetyl-1,2-O-isopropylidene-alpha-D-glucofuranuronate or its 3-O-trityl derivative and subsequent furanose----pyranose transformation. The derivatives 8 and 20 were each copolymerised with acrylamide. In serological tests (enzyme immunoassay and passive hemagglutination), the resulting antigens exhibited the specificity of S3. It was concluded that fragment A was a much stronger immunodeterminant than fragment B."
1231020,Dutton and  Lim 1985,Structure of the capsular polysaccharide of Klebsiella serotype K79,"The structure of the capsular polysaccharide from Klebsiella K79 was determined by the techniques of methylation, periodate oxidation, beta-elimination, chromic acid oxidation, and partial hydrolysis. N.m.r. spectroscopy (1H and 13C) was used extensively to establish the nature of the anomeric linkages of the polysaccharide and of oligosaccharides derived through degradative procedures. The polysaccharide was found to have the heptasaccharide, &quot;5 + 2&quot; repeating unit: (Formula: see text).","Structure of the capsular polysaccharide of Klebsiella serotype K79 Abs: The structure of the capsular polysaccharide from Klebsiella K79 was determined by the techniques of methylation, periodate oxidation, beta-elimination, chromic acid oxidation, and partial hydrolysis. N.m.r. spectroscopy (1H and 13C) was used extensively to establish the nature of the anomeric linkages of the polysaccharide and of oligosaccharides derived through degradative procedures. The polysaccharide was found to have the heptasaccharide, &quot;5 + 2&quot; repeating unit: (Formula: see text)."
1231018,Schindelmeiser 1986,"Light and electron microscopic study on complex carbohydrates in the testis of Salamandra salamandra L. (Amphibia, Urodela)","The distribution of complex carbohydrates was studied in the testis of the European fire salamander, Salamandra salamandra, by light- and electron-microscopic methods. The basal laminae and fibrous structures in the connective tissue between the lobules are PAS-positive. After alcianblue staining (at pH = 2.8), acid mucopolysaccharides could be demonstrated in steroid hormone-producing cells in the interstitial tissue between lobules containing spermatids, spermatozoa, and lobules after spermiation, as well as in most of the Sertoli cells in lobules after spermiation. In all spermatogenic stages from secondary spermatocytes to mature sperms, dictyosome-like structures and flat vesicles showed a distinct contrast enhancement, as did parts of the acrosome after treatment with the phosphotungstic acid-chromic acid method for electron microscopy.","Light and electron microscopic study on complex carbohydrates in the testis of Salamandra salamandra L. (Amphibia, Urodela) Abs: The distribution of complex carbohydrates was studied in the testis of the European fire salamander, Salamandra salamandra, by light- and electron-microscopic methods. The basal laminae and fibrous structures in the connective tissue between the lobules are PAS-positive. After alcianblue staining (at pH = 2.8), acid mucopolysaccharides could be demonstrated in steroid hormone-producing cells in the interstitial tissue between lobules containing spermatids, spermatozoa, and lobules after spermiation, as well as in most of the Sertoli cells in lobules after spermiation. In all spermatogenic stages from secondary spermatocytes to mature sperms, dictyosome-like structures and flat vesicles showed a distinct contrast enhancement, as did parts of the acrosome after treatment with the phosphotungstic acid-chromic acid method for electron microscopy."
1231016,Fetter and  Costello 1986,A procedure for obtaining complementary replicas of ultra-rapidly frozen sandwiched samples,"Complementary replicas of samples prepared for electron microscopy by the freeze-fracture/etch technique are extremely valuable in the interpretation of the exposed surfaces, the nature and location of the membrane fracture plane, and as an aid in the recognition of the potential artefacts of this technique. This paper describes a procedure for the preparation of complementary replicas of thin samples sandwiched between copper foil strips and frozen ultra-rapidly in the absence of chemical pretreatments. In this procedure, the copper foil support bearing the replica is floated on the surface of a chromic acid solution, resulting in the controlled dissolution of the copper metal. The replica which remains at the surface of the chromic acid is then stabilized against fragmentation during subsequent cleaning and rinsing steps by placing a 50 mesh gold grid on top of the replica. To minimize agitation of the replica/grid, all cleaning steps are performed in a single depression plate well. The clean replica/grid is picked up from below on a thin Formvar film, dried, and then separated from the extra film. Careful placement of the gold grid on the replicas and low magnification electron micrograph montages of the complementary grids facilitate the location of complementary regions and simplify examination of complementary specimen areas at higher magnification.","A procedure for obtaining complementary replicas of ultra-rapidly frozen sandwiched samples Abs: Complementary replicas of samples prepared for electron microscopy by the freeze-fracture/etch technique are extremely valuable in the interpretation of the exposed surfaces, the nature and location of the membrane fracture plane, and as an aid in the recognition of the potential artefacts of this technique. This paper describes a procedure for the preparation of complementary replicas of thin samples sandwiched between copper foil strips and frozen ultra-rapidly in the absence of chemical pretreatments. In this procedure, the copper foil support bearing the replica is floated on the surface of a chromic acid solution, resulting in the controlled dissolution of the copper metal. The replica which remains at the surface of the chromic acid is then stabilized against fragmentation during subsequent cleaning and rinsing steps by placing a 50 mesh gold grid on top of the replica. To minimize agitation of the replica/grid, all cleaning steps are performed in a single depression plate well. The clean replica/grid is picked up from below on a thin Formvar film, dried, and then separated from the extra film. Careful placement of the gold grid on the replicas and low magnification electron micrograph montages of the complementary grids facilitate the location of complementary regions and simplify examination of complementary specimen areas at higher magnification."
1231013,Bader 1986,Acute renal failure after chromic acid injection,,Acute renal failure after chromic acid injection Abs: 
1231012,Evangelista and  Sefton 1986,Coating of two polyether-polyurethanes and polyethylene with a heparin-poly-(vinyl alcohol) hydrogel,Two polyether-polyurethane elastomers (Pellethane and Biomer) and polyethylene were coated with a heparin-poly(vinyl alcohol) hydrogel. The requisite surface modification in preparation for coating consisted of glow discharge cleaning and acid treatment for the polyether-polyurethanes and glow discharge cleaning and chromic acid oxidation for polyethylene. The chemical modifications increased surface wettability. Surface analysis by attenuated total reflectance Fourier transform infrared spectroscopy indicated that the acid treatment caused hydrolysis of the polyether segments of Pellethane and Biomer. Prolonged partial thromboplastin times were observed on the coated films. The results of toluidine blue assay of heparin in the solution in which the coated films were immersed for a long time suggested that heparin was covalently bound in the coating. Such coating techniques extend the usefulness of the heparin-poly(vinyl alcohol) hydrogel to a number of medically important substrate materials.,Coating of two polyether-polyurethanes and polyethylene with a heparin-poly-(vinyl alcohol) hydrogel Abs: Two polyether-polyurethane elastomers (Pellethane and Biomer) and polyethylene were coated with a heparin-poly(vinyl alcohol) hydrogel. The requisite surface modification in preparation for coating consisted of glow discharge cleaning and acid treatment for the polyether-polyurethanes and glow discharge cleaning and chromic acid oxidation for polyethylene. The chemical modifications increased surface wettability. Surface analysis by attenuated total reflectance Fourier transform infrared spectroscopy indicated that the acid treatment caused hydrolysis of the polyether segments of Pellethane and Biomer. Prolonged partial thromboplastin times were observed on the coated films. The results of toluidine blue assay of heparin in the solution in which the coated films were immersed for a long time suggested that heparin was covalently bound in the coating. Such coating techniques extend the usefulness of the heparin-poly(vinyl alcohol) hydrogel to a number of medically important substrate materials.
1231011,Gustafsson et al. 1986,Immunohistochemical and ultrastructural observations on adenoid cystic carcinoma of salivary glands. With special reference to intermediate filaments and proteoglycan particles,"In adenoid cystic carcinoma (ACC) of salivary gland origin, intermediate filaments of tumour cells were investigated by immunohistochemical techniques and complex carbohydrates within the pseudocysts by ultrastructural methods. The intermediate filament proteins vimentin and cytokeratin were found in most neoplastic cells. The pseudocysts of the tumours were found to contain proteoglycan particles stainable after glutaraldehyde fixation--but not after osmium fixation alone. Ruthenium red (cationic dye) enhanced the staining whereas periodic acid-chromic acid-silver methenamine staining or phosphotungstic acid staining did not visualize the proteoglycan particles mainly containing acid proteoglycans which are normally produced by mesenchymal tissue. The cells of adenoid cystic carcinoma thus have an intermediate filament content and produce complex carbohydrates characteristic of both epithelial and mesenchymal tissue. Hence, an origin in an undifferentiated pluripotential cell seems plausible.","Immunohistochemical and ultrastructural observations on adenoid cystic carcinoma of salivary glands. With special reference to intermediate filaments and proteoglycan particles Abs: In adenoid cystic carcinoma (ACC) of salivary gland origin, intermediate filaments of tumour cells were investigated by immunohistochemical techniques and complex carbohydrates within the pseudocysts by ultrastructural methods. The intermediate filament proteins vimentin and cytokeratin were found in most neoplastic cells. The pseudocysts of the tumours were found to contain proteoglycan particles stainable after glutaraldehyde fixation--but not after osmium fixation alone. Ruthenium red (cationic dye) enhanced the staining whereas periodic acid-chromic acid-silver methenamine staining or phosphotungstic acid staining did not visualize the proteoglycan particles mainly containing acid proteoglycans which are normally produced by mesenchymal tissue. The cells of adenoid cystic carcinoma thus have an intermediate filament content and produce complex carbohydrates characteristic of both epithelial and mesenchymal tissue. Hence, an origin in an undifferentiated pluripotential cell seems plausible."
1231010,Walton et al. 1986,Age and sex incidence of allergic contact dermatitis,"A retrospective study of patients patch tested between 1968 and 1970 was undertaken and case records of 200 patients with unequivocal positive patch tests were studied for age and sex distribution. There was an overall female preponderance (61%), with 2 peaks of incidence in the 10-20 and 40-50 year age groups in females, but only 1 peak of incidence in the 40-50 year age group in males. There was a steady decline in all sensitivities after the 6th decade of life in both sexes. Nickel sensitivity was more common in females (92%), whereas dichromate sensitivity predominated in males (64%). Of the 200 patients, only 5(2.5%) were atopics, all of whom were females.","Age and sex incidence of allergic contact dermatitis Abs: A retrospective study of patients patch tested between 1968 and 1970 was undertaken and case records of 200 patients with unequivocal positive patch tests were studied for age and sex distribution. There was an overall female preponderance (61%), with 2 peaks of incidence in the 10-20 and 40-50 year age groups in females, but only 1 peak of incidence in the 40-50 year age group in males. There was a steady decline in all sensitivities after the 6th decade of life in both sexes. Nickel sensitivity was more common in females (92%), whereas dichromate sensitivity predominated in males (64%). Of the 200 patients, only 5(2.5%) were atopics, all of whom were females."
1231009,Goldberg and  Septier 1986,Ultrastructural location of complex carbohydrates in developing rat incisor enamel,"The ultrastructural distribution of complex carbohydrates in an early formation stage of rat incisor enamel was investigated by staining with the periodic acid-thiocarbohydrazide-silver proteinate reaction (PA-TCH-SP) for vicinal glycol-containing glycoconjugates, the phosphotungstic acid-chromic acid mixture (PTA) for glycoproteins, and the cationic dyes alcian blue or bismuth nitrate for sulfated glycoconjugates. In order to remove selectively sulfated complex carbohydrates, half of the serial sections obtained were digested with a bovine testicular hyaluronidase prior to staining. Far fewer electron-dense deposits were observed with the PA-TCH-SP method on hyaluronidase-treated sections, especially those subsequently treated for 48 hours with TCH. On the other hand, the minimal staining obtained with PTA was much more intense on sections treated with hyaluronidase where linear fiberlike structures were observed. With cationic dyes, staining of dotlike alignment structures and ground substance was obtained but was completely abolished by hyaluronidase treatment. Cuprolinic blue in a critical electrolyte concentration, ruthenium hexamine trichloride used with aldehyde during fixation, as well as rapid-freezing followed by freeze-substitution validate that this dotlike distribution is not an artefact of processing. The staining results demonstrated that the glycoproteins and sulfated complex carbohydrates in developing rat incisor enamel each display a specific distribution pattern. The glycoproteins were present as fiberlike structures and the sulfated carbohydrates appeared as dotlike formations located close to the surface of the fiberlike structures, and/or in the spaces between them.","Ultrastructural location of complex carbohydrates in developing rat incisor enamel Abs: The ultrastructural distribution of complex carbohydrates in an early formation stage of rat incisor enamel was investigated by staining with the periodic acid-thiocarbohydrazide-silver proteinate reaction (PA-TCH-SP) for vicinal glycol-containing glycoconjugates, the phosphotungstic acid-chromic acid mixture (PTA) for glycoproteins, and the cationic dyes alcian blue or bismuth nitrate for sulfated glycoconjugates. In order to remove selectively sulfated complex carbohydrates, half of the serial sections obtained were digested with a bovine testicular hyaluronidase prior to staining. Far fewer electron-dense deposits were observed with the PA-TCH-SP method on hyaluronidase-treated sections, especially those subsequently treated for 48 hours with TCH. On the other hand, the minimal staining obtained with PTA was much more intense on sections treated with hyaluronidase where linear fiberlike structures were observed. With cationic dyes, staining of dotlike alignment structures and ground substance was obtained but was completely abolished by hyaluronidase treatment. Cuprolinic blue in a critical electrolyte concentration, ruthenium hexamine trichloride used with aldehyde during fixation, as well as rapid-freezing followed by freeze-substitution validate that this dotlike distribution is not an artefact of processing. The staining results demonstrated that the glycoproteins and sulfated complex carbohydrates in developing rat incisor enamel each display a specific distribution pattern. The glycoproteins were present as fiberlike structures and the sulfated carbohydrates appeared as dotlike formations located close to the surface of the fiberlike structures, and/or in the spaces between them."
1231008,Tracy et al. 1987,Sequestration hypothesis of atherosclerosis,"Atherosclerosis of the human aorta has been studied by morphometric, chemical, and histochemical methods. Results of these separate approaches are converging upon a theory of pathogenesis. This theory begins with the standard view of a two stage process, intimal fibroplasia followed by atheronecrosis in the most thickened and aged places. The first stage, fibroplasia, can be described in terms of a stochastic process wherein smooth muscle cells, scattered in accordance with a Poison distribution, elaborate matrix materials over time, causing the realms of the cells to expand and to aggregate. The fusion of the expanded smooth muscle cell realms seems to mark the advent of necrosis. The second stage, atheronecrosis, can be described such that the probability of a necrotic core emerging at a site in a vessel is governed by the amount and the age of interstitial matrix materials at the site. Further evidence shows that the matrix materials tend to sequester lipids in greater than proportionate amounts as the intimal bulk increases. The sequestered perifibrous lipid is histochemically different from the lipids of the necrotic core, in that only the latter can be fixed with chromic acid. These results suggest that lipids undergo a qualitative change as well as a quantitative increase at the stage of impending necrosis. This qualitative change is governed by age, which raises the possibility that necrotizing toxicity accumulates in the sequestered lipid as it ages.","Sequestration hypothesis of atherosclerosis Abs: Atherosclerosis of the human aorta has been studied by morphometric, chemical, and histochemical methods. Results of these separate approaches are converging upon a theory of pathogenesis. This theory begins with the standard view of a two stage process, intimal fibroplasia followed by atheronecrosis in the most thickened and aged places. The first stage, fibroplasia, can be described in terms of a stochastic process wherein smooth muscle cells, scattered in accordance with a Poison distribution, elaborate matrix materials over time, causing the realms of the cells to expand and to aggregate. The fusion of the expanded smooth muscle cell realms seems to mark the advent of necrosis. The second stage, atheronecrosis, can be described such that the probability of a necrotic core emerging at a site in a vessel is governed by the amount and the age of interstitial matrix materials at the site. Further evidence shows that the matrix materials tend to sequester lipids in greater than proportionate amounts as the intimal bulk increases. The sequestered perifibrous lipid is histochemically different from the lipids of the necrotic core, in that only the latter can be fixed with chromic acid. These results suggest that lipids undergo a qualitative change as well as a quantitative increase at the stage of impending necrosis. This qualitative change is governed by age, which raises the possibility that necrotizing toxicity accumulates in the sequestered lipid as it ages."
1231007,Adachi 1987,[Effects of chromium compounds on the respiratory system. 5. Long term inhalation of chromic acid mist in electroplating by C57BL female mice and recapitulation of our experimental studies],"Long term inhalation of CrO3 mist by C57BL mice The effects of the chromic acid mist used in electroplating on the respiratory system of C57BL mice (female; n = 43) were examined histopathologically after exposure for 12 months to the mist (1.81 mgCr/m3-120 min, twice a week). Among the 23 mice sacrificed at 12 months after the first exposure, three cases of perforation in the nasal septs, a case of proliferative change of the tracheal epithelium, nine cases of emphysema and four of adenomatous metaplasia of the lungs were observed on antopsy. Among the 20 mice which were sacrificed six months after the last exposure, the same changes as the 12-month exposure group were also observed in the nasal septum, trachea and lungs, but papillomas observed in the nasal epithelia of six mice and adenoma in the lung of a mouse were new findings not seen in the 12-month exposure group. These results suggest that, in view of the low incidence of spontaneous lung tumor in C57BL mice, inhalation of chromic acid mist in electroplating might be a risk factor of lung cancer. Additionally, the occurrence of papillomas in the nasal epithelium demonstrates the need of directing attention to the possible development of cancer of the upper respiratory tract in chromium electroplating workers. Recapitulation on our experimental studies Upon completion of our five reports on the effects of chromium compounds on the respiratory system, a recapitulation of our experimental studies was made and compared with the findings of a number of reports on chromium. It was experimentally and epidemiologically confirmed that hexavalent chromium compounds act as carcinogens and cause specific biological effects on the respiratory system. These characteristics of hexavalent compounds might be attributable to the strong oxidizing potency and/or high permeability through the cell membrane. Furthermore, hexavalent compounds might be entirely different in biological action from trivalent compounds which are chemically most stable.","[Effects of chromium compounds on the respiratory system. 5. Long term inhalation of chromic acid mist in electroplating by C57BL female mice and recapitulation of our experimental studies] Abs: Long term inhalation of CrO3 mist by C57BL mice The effects of the chromic acid mist used in electroplating on the respiratory system of C57BL mice (female; n = 43) were examined histopathologically after exposure for 12 months to the mist (1.81 mgCr/m3-120 min, twice a week). Among the 23 mice sacrificed at 12 months after the first exposure, three cases of perforation in the nasal septs, a case of proliferative change of the tracheal epithelium, nine cases of emphysema and four of adenomatous metaplasia of the lungs were observed on antopsy. Among the 20 mice which were sacrificed six months after the last exposure, the same changes as the 12-month exposure group were also observed in the nasal septum, trachea and lungs, but papillomas observed in the nasal epithelia of six mice and adenoma in the lung of a mouse were new findings not seen in the 12-month exposure group. These results suggest that, in view of the low incidence of spontaneous lung tumor in C57BL mice, inhalation of chromic acid mist in electroplating might be a risk factor of lung cancer. Additionally, the occurrence of papillomas in the nasal epithelium demonstrates the need of directing attention to the possible development of cancer of the upper respiratory tract in chromium electroplating workers. Recapitulation on our experimental studies Upon completion of our five reports on the effects of chromium compounds on the respiratory system, a recapitulation of our experimental studies was made and compared with the findings of a number of reports on chromium. It was experimentally and epidemiologically confirmed that hexavalent chromium compounds act as carcinogens and cause specific biological effects on the respiratory system. These characteristics of hexavalent compounds might be attributable to the strong oxidizing potency and/or high permeability through the cell membrane. Furthermore, hexavalent compounds might be entirely different in biological action from trivalent compounds which are chemically most stable."
1231006,Kang et al. 1987,Immunoultrastructural studies of human NK cells: II. Effector-target cell binding and phagocytosis,"The binding of NK cells to a target cell appears to be a necessary step for NK cell-mediated cytolysis. In this report, we demonstrated effector-target binding by immunoelectron microscopy by using monoclonal antibodies against NK cells (Leu-7, Leu-11a) and T-cell subsets (Leu-2a/T8, Leu-3a/T4). The surfaces of NK and K562 cells were characterized by antitransferrin receptor antibody and various lectins. In addition, the controversial phagocytic activity of NK cells was studied by incubation of peripheral blood mononuclear cells with opsonized Staphylococcus aureus and labeling with anti-Leu-7 or anti-Leu-11a antibody. Results showed that only Leu-11a+ cells displayed a broad cell-to-cell contact with the target by a shallow intercellular interdigitation of cytoplasmic projections, while Leu-7+, Leu-2a+, or Leu3a+ cells showed only a partial contact with target without interdigitation. The Leu-11a+ cells were frequently observed in small clusters and in close association with monocytes. Cluster formation and association with monocytes were not observed in other NK and T-cell immunophenotypes. In Leu-11a+ cells conjugated with target cells, membrane-bound granules, small vesicles, parallel tubular arrays, Golgi apparatus, endoplasmic reticulum, and small vacuoles were evident and concentrated toward the target. The surface of NK cells was intensely stained for glycoprotein by chromic acid-phosphotungstic acid, whereas target cells were not stained. Transferrin receptors were stained only on the surface of target cells. Only the lectins RCA and UEA labeled the surfaces of both NK and target cells. Phagocytic vacuoles containing cell debris or fragments and ingested bacteria were found in the cytoplasm of Leu-11a+ cells but not in Leu-7+ cells. NK cells were also found within the cytoplasm of K562 target cells. All these findings suggest that Leu-11a+ cells are the true functional NK cells involved in NK cell-mediated cytolysis, phagocytosis, and emperipolesis. Therefore, the NK cell is probably &quot;a phagocyte in lymphocyte's clothing.&quot; The presence of peroxidase in the small vesicles of NK cells and endocytotic vesicles of target cells at the effector-target contact area indicates that cytolytic enzymes or factors derived from NK cells may be transported into the target by endocytosis.","Immunoultrastructural studies of human NK cells: II. Effector-target cell binding and phagocytosis Abs: The binding of NK cells to a target cell appears to be a necessary step for NK cell-mediated cytolysis. In this report, we demonstrated effector-target binding by immunoelectron microscopy by using monoclonal antibodies against NK cells (Leu-7, Leu-11a) and T-cell subsets (Leu-2a/T8, Leu-3a/T4). The surfaces of NK and K562 cells were characterized by antitransferrin receptor antibody and various lectins. In addition, the controversial phagocytic activity of NK cells was studied by incubation of peripheral blood mononuclear cells with opsonized Staphylococcus aureus and labeling with anti-Leu-7 or anti-Leu-11a antibody. Results showed that only Leu-11a+ cells displayed a broad cell-to-cell contact with the target by a shallow intercellular interdigitation of cytoplasmic projections, while Leu-7+, Leu-2a+, or Leu3a+ cells showed only a partial contact with target without interdigitation. The Leu-11a+ cells were frequently observed in small clusters and in close association with monocytes. Cluster formation and association with monocytes were not observed in other NK and T-cell immunophenotypes. In Leu-11a+ cells conjugated with target cells, membrane-bound granules, small vesicles, parallel tubular arrays, Golgi apparatus, endoplasmic reticulum, and small vacuoles were evident and concentrated toward the target. The surface of NK cells was intensely stained for glycoprotein by chromic acid-phosphotungstic acid, whereas target cells were not stained. Transferrin receptors were stained only on the surface of target cells. Only the lectins RCA and UEA labeled the surfaces of both NK and target cells. Phagocytic vacuoles containing cell debris or fragments and ingested bacteria were found in the cytoplasm of Leu-11a+ cells but not in Leu-7+ cells. NK cells were also found within the cytoplasm of K562 target cells. All these findings suggest that Leu-11a+ cells are the true functional NK cells involved in NK cell-mediated cytolysis, phagocytosis, and emperipolesis. Therefore, the NK cell is probably &quot;a phagocyte in lymphocyte's clothing.&quot; The presence of peroxidase in the small vesicles of NK cells and endocytotic vesicles of target cells at the effector-target contact area indicates that cytolytic enzymes or factors derived from NK cells may be transported into the target by endocytosis."
1231005,Murthy et al. 1987,"Utilization of immunogold labeling to compare the adsorption behavior of fibrinogen, fibronectin and albumin on polymers","Immunogold labeling followed by scanning electron microscopy (SEM) was used to examine the surface distribution of adsorbed plasma proteins. Adsorption was performed under various conditions on six different polymers; [low density polyethylene (PE), chromic acid-oxidized PE (OXPE), solution grade Biomer (SB), Teflon-(FEP), a laboratory synthesized polyurethane containing some zwitterions (ZW) and a polydimethylsiloxane based polyurethane (ZS) also containing zwitterions]. The proteins used were purified human and canine fibrinogen, fibronectin, and serum albumin. The immunogold staining technique was successful in the labeling of the adsorbed proteins. The adsorbed proteins were distributed differently on the polymers selected. Human and canine fibrinogen were found to cover all surfaces in a dense, uniform fashion. Albumin covered most surfaces in a less uniform fashion and on the zwitterionomers covered only a portion of the surface, leaving large bare patches. Fibronectin appeared to deposit unevenly, forming a network on part of the surface and uniformly coating other parts.","Utilization of immunogold labeling to compare the adsorption behavior of fibrinogen, fibronectin and albumin on polymers Abs: Immunogold labeling followed by scanning electron microscopy (SEM) was used to examine the surface distribution of adsorbed plasma proteins. Adsorption was performed under various conditions on six different polymers; [low density polyethylene (PE), chromic acid-oxidized PE (OXPE), solution grade Biomer (SB), Teflon-(FEP), a laboratory synthesized polyurethane containing some zwitterions (ZW) and a polydimethylsiloxane based polyurethane (ZS) also containing zwitterions]. The proteins used were purified human and canine fibrinogen, fibronectin, and serum albumin. The immunogold staining technique was successful in the labeling of the adsorbed proteins. The adsorbed proteins were distributed differently on the polymers selected. Human and canine fibrinogen were found to cover all surfaces in a dense, uniform fashion. Albumin covered most surfaces in a less uniform fashion and on the zwitterionomers covered only a portion of the surface, leaving large bare patches. Fibronectin appeared to deposit unevenly, forming a network on part of the surface and uniformly coating other parts."
1231004,Marschall et al. 1987,"6 alpha-glucuronidation of hyodeoxycholic acid by human liver, kidney and small bowel microsomes","Kinetic constants for the glucuronidation of hyodeoxycholic acid in man were determined using microsomal preparations of liver, kidney and small bowel. The affinity of hyodeoxycholic acid for the microsomal hepatic and extrahepatic enzymes was in the same range as previously observed for the monohydroxy bile acid lithocholic acid and about 3-14-times the affinity for the dihydroxy bile acids chenodeoxycholic, deoxycholic and ursodeoxycholic acids. The Vmax values for glucuronidation of hyodeoxycholic acid with hepatic microsomes were 10-30-times higher and with kidney microsomes 50-110-times higher than for the bile acids lacking a 6 alpha-hydroxy group. The site of glucuronidation was determined by gas chromatographic-mass spectrometric analysis of derivatives of products formed after periodate and chromic acid oxidation. Hyodeoxycholic acid glucuronides synthesized with microsomal preparations from the three organs were all found to be conjugated at the 6 alpha position. This has previously been shown to be the site of glucuronidation of endogenous hyodeoxycholic acid glucuronide excreted in urine.","6 alpha-glucuronidation of hyodeoxycholic acid by human liver, kidney and small bowel microsomes Abs: Kinetic constants for the glucuronidation of hyodeoxycholic acid in man were determined using microsomal preparations of liver, kidney and small bowel. The affinity of hyodeoxycholic acid for the microsomal hepatic and extrahepatic enzymes was in the same range as previously observed for the monohydroxy bile acid lithocholic acid and about 3-14-times the affinity for the dihydroxy bile acids chenodeoxycholic, deoxycholic and ursodeoxycholic acids. The Vmax values for glucuronidation of hyodeoxycholic acid with hepatic microsomes were 10-30-times higher and with kidney microsomes 50-110-times higher than for the bile acids lacking a 6 alpha-hydroxy group. The site of glucuronidation was determined by gas chromatographic-mass spectrometric analysis of derivatives of products formed after periodate and chromic acid oxidation. Hyodeoxycholic acid glucuronides synthesized with microsomal preparations from the three organs were all found to be conjugated at the 6 alpha position. This has previously been shown to be the site of glucuronidation of endogenous hyodeoxycholic acid glucuronide excreted in urine."
1231002,Zeeck et al. 1987,"The structure of manumycin. I. Characterization, structure elucidation and biological activity","Manumycin (1), produced by Streptomyces parvulus (strain Tü 64), was isolated from the mycelium by extraction with acetone and could easily be purified chromatographically. Chemical degradation of 1 (C31H38N2O7) gave 2-acetamino-3-hydroxycyclopent-2-enone (2) by acetolysis, 2,4,6-trimethyl-2,4-decadienoic acid (3) by alkaline hydrolysis, and 2-(2,4,6-trimethyl-2,4-decadienoylamino)-5,6-epoxy-1,4-benzoquinon e (5) by chromic acid oxidation. In connection with a detailed spectroscopic analysis, the structure of 1 could be elucidated and the (E)-configuration of the double bonds in the triene and diene chain was established. Manumycin exhibits biological activity against Gram-positive bacteria and fungi and furthermore, an inhibition of the developmental processes of some insects.","The structure of manumycin. I. Characterization, structure elucidation and biological activity Abs: Manumycin (1), produced by Streptomyces parvulus (strain Tü 64), was isolated from the mycelium by extraction with acetone and could easily be purified chromatographically. Chemical degradation of 1 (C31H38N2O7) gave 2-acetamino-3-hydroxycyclopent-2-enone (2) by acetolysis, 2,4,6-trimethyl-2,4-decadienoic acid (3) by alkaline hydrolysis, and 2-(2,4,6-trimethyl-2,4-decadienoylamino)-5,6-epoxy-1,4-benzoquinon e (5) by chromic acid oxidation. In connection with a detailed spectroscopic analysis, the structure of 1 could be elucidated and the (E)-configuration of the double bonds in the triene and diene chain was established. Manumycin exhibits biological activity against Gram-positive bacteria and fungi and furthermore, an inhibition of the developmental processes of some insects."
1231001,Thiericke et al. 1987,The structure of manumycin. III. Absolute configuration and conformational studies,"Chromic acid oxidation of manumycin (1), an antibiotic produced by Streptomyces parvulus (strain Tü 64), led to the isolation of 2-(2-methyl-4-oxo-2-pentenoylamino)-5,6-epoxy-1,4-benzoquinone (3) and (-)-(R)-2-methylhexanoic acid (4). From the absolute configuration of 4, determined by comparing its optical rotation with published data, follows the absolute configuration at the center of chirality in the diene side chain of manumycin (1) to be (6'R). Based on the direct comparison of the CD spectra of the two chromic acid oxidation products 2 and 3 with those of the antibiotic G7063-2 (5) and (-)-terreic acid (6) the stereochemistry at C-5 and C-6 of 1 was determined as (5R, 6S). From the negative CD-couplet of manumycin (1) its stereochemistry at C-4 was assigned as (4R).","The structure of manumycin. III. Absolute configuration and conformational studies Abs: Chromic acid oxidation of manumycin (1), an antibiotic produced by Streptomyces parvulus (strain Tü 64), led to the isolation of 2-(2-methyl-4-oxo-2-pentenoylamino)-5,6-epoxy-1,4-benzoquinone (3) and (-)-(R)-2-methylhexanoic acid (4). From the absolute configuration of 4, determined by comparing its optical rotation with published data, follows the absolute configuration at the center of chirality in the diene side chain of manumycin (1) to be (6'R). Based on the direct comparison of the CD spectra of the two chromic acid oxidation products 2 and 3 with those of the antibiotic G7063-2 (5) and (-)-terreic acid (6) the stereochemistry at C-5 and C-6 of 1 was determined as (5R, 6S). From the negative CD-couplet of manumycin (1) its stereochemistry at C-4 was assigned as (4R)."
1231000,Gruys et al. 1987,Synthesis and properties of 2-acetylthiamin pyrophosphate: an enzymatic reaction intermediate,"The synthesis of 2-acetylthiamin pyrophosphate (acetyl-TPP) is described. The synthesis of this compound is accomplished at 23 degrees C by the oxidation of 2-(1-hydroxyethyl)thiamin pyrophosphate using aqueous chromic acid as the oxidizing agent under conditions where Cr(III) coordination to the pyrophosphoryl moiety and hydrolysis of both the pyrophosphate and acetyl moieties were prevented. Although the chemical properties exhibited by acetyl-TPP are similar to those of the 2-acetyl-3,4-dimethylthiazolium ion examined by Lienhard [Lienhard, G.E. (1966) J. Am. Chem. Soc. 88, 5642-5649], significant differences exist because of the pyrimidine ring in acetyl-TPP. Characterization of acetyl-TPP by ultraviolet spectroscopy, 1H NMR, 13C NMR, and 31P NMR provided evidence that the compound in aqueous solution exists as an equilibrium mixture of keto, hydrate, and intramolecular carbinolamine forms. The equilibria for the hydration and carbinolamine formation reactions at pD 1.3 as determined by 1H NMR are strongly dependent on the temperature, showing an increase in the hydrate and carbinolamine forms at the expense of the keto form with decreasing temperature. The concentration of keto form also decreases with increasing pH. Acetyl-TPP is stable in aqueous acid but rapidly deacetylates at higher pH to form acetate and thiamin pyrophosphate. Trapping of the acetyl moiety in aqueous solution occurs efficiently with 1.0 M hydroxylamine at pH 5.5-6.5 to form acetohydroxamic acid and to a much smaller extent with 1.0 M 2-mercaptoethanol at pH 4.0 and 5.0 to form thio ester. Transfer of the acetyl group to 0.5 M dihydrolipoic acid at pH 5.0 and 1.0 M phosphate dianion at pH 7.0 is not observed to any significant extent in water. The kinetic and thermodynamic reactivity of acetyl-TPP with water and other nucleophiles is compatible with a hypothetical role for acyl-TPPs as enzymatic acyl-transfer intermediates.","Synthesis and properties of 2-acetylthiamin pyrophosphate: an enzymatic reaction intermediate Abs: The synthesis of 2-acetylthiamin pyrophosphate (acetyl-TPP) is described. The synthesis of this compound is accomplished at 23 degrees C by the oxidation of 2-(1-hydroxyethyl)thiamin pyrophosphate using aqueous chromic acid as the oxidizing agent under conditions where Cr(III) coordination to the pyrophosphoryl moiety and hydrolysis of both the pyrophosphate and acetyl moieties were prevented. Although the chemical properties exhibited by acetyl-TPP are similar to those of the 2-acetyl-3,4-dimethylthiazolium ion examined by Lienhard [Lienhard, G.E. (1966) J. Am. Chem. Soc. 88, 5642-5649], significant differences exist because of the pyrimidine ring in acetyl-TPP. Characterization of acetyl-TPP by ultraviolet spectroscopy, 1H NMR, 13C NMR, and 31P NMR provided evidence that the compound in aqueous solution exists as an equilibrium mixture of keto, hydrate, and intramolecular carbinolamine forms. The equilibria for the hydration and carbinolamine formation reactions at pD 1.3 as determined by 1H NMR are strongly dependent on the temperature, showing an increase in the hydrate and carbinolamine forms at the expense of the keto form with decreasing temperature. The concentration of keto form also decreases with increasing pH. Acetyl-TPP is stable in aqueous acid but rapidly deacetylates at higher pH to form acetate and thiamin pyrophosphate. Trapping of the acetyl moiety in aqueous solution occurs efficiently with 1.0 M hydroxylamine at pH 5.5-6.5 to form acetohydroxamic acid and to a much smaller extent with 1.0 M 2-mercaptoethanol at pH 4.0 and 5.0 to form thio ester. Transfer of the acetyl group to 0.5 M dihydrolipoic acid at pH 5.0 and 1.0 M phosphate dianion at pH 7.0 is not observed to any significant extent in water. The kinetic and thermodynamic reactivity of acetyl-TPP with water and other nucleophiles is compatible with a hypothetical role for acyl-TPPs as enzymatic acyl-transfer intermediates."
1230999,Horn et al. 1988,Light microscopical demonstration and zonal distribution of parasinusoidal cells (Ito cells) in normal human liver,"The parasinusoidal cells of the liver (Ito cells) were demonstrated light microscopically in autopsy specimens fixed in formalin and stained with Oil red O after dichromate treatment. The method allows examination of large samples containing numerous acini. Quantitative assessment showed a zonal gradient with 6.3 and 7.7 parasinusoidal cells per 62.5 X 10(3) micron2 in zone 1 and 3, respectively.","Light microscopical demonstration and zonal distribution of parasinusoidal cells (Ito cells) in normal human liver Abs: The parasinusoidal cells of the liver (Ito cells) were demonstrated light microscopically in autopsy specimens fixed in formalin and stained with Oil red O after dichromate treatment. The method allows examination of large samples containing numerous acini. Quantitative assessment showed a zonal gradient with 6.3 and 7.7 parasinusoidal cells per 62.5 X 10(3) micron2 in zone 1 and 3, respectively."
1230998,Wilson and  Lowensohn 1988,Validation of viscosity measurements for canine hepatic bile,"This study developed the validated standards for a known viscosity method by obtaining consistent viscosity measurements with defined precision, reproducibility and sensitivity limits for canine hepatic bile. Size 75 Cannon-Manning semimicro viscometers yielded the most precise viscosity measurements. With the development of proper handling methods for fresh bile samples, a precision defined by a coefficient of variation of less than or equal to +/- 0.3% was obtained. To maintain viscometer constancy, the viscometers must be cleaned with chromic acid after each bile test and pass reproducibility tests using defined distilled water viscosity tests.","Validation of viscosity measurements for canine hepatic bile Abs: This study developed the validated standards for a known viscosity method by obtaining consistent viscosity measurements with defined precision, reproducibility and sensitivity limits for canine hepatic bile. Size 75 Cannon-Manning semimicro viscometers yielded the most precise viscosity measurements. With the development of proper handling methods for fresh bile samples, a precision defined by a coefficient of variation of less than or equal to +/- 0.3% was obtained. To maintain viscometer constancy, the viscometers must be cleaned with chromic acid after each bile test and pass reproducibility tests using defined distilled water viscosity tests."
1230997,Lee and  Goh 1988,Occupational dermatosis among chrome platers,"14 (38%) of 37 chrome platers in 17 chrome electroplating factories surveyed had occupational contact dermatitis, chrome ulcers, or both. 7 had chrome ulcers, 6 had contact dermatitis and 1 had both. Another 16 (43%) workers had scars suggestive of previous chrome ulcers. Mucosal irritation was present in 57% of the workers. The most common was throat irritation (49%) followed by nasal irritation (41%). Mucosal irritation was more common in hard chrome platers, while skin ulcers and dermatitis were more common in bright chrome platers. Nasal septum perforation was seen in 1 worker. Skin ulceration appeared to be a more specific sign for occupational dermatosis in chrome platers than dermatitis when the prevalence rates were compared to controls. Of the 7 workers with chrome ulcers, only 1 was allergic to chromate. Of the 6 workers with dermatitis, 2 were allergic to chromate and 1 to nickel. The worker with ulceration and dermatitis was negative to chromate and nickel. Irritant factors are therefore important in the aetiology of contact dermatitis in these chrome platers.","Occupational dermatosis among chrome platers Abs: 14 (38%) of 37 chrome platers in 17 chrome electroplating factories surveyed had occupational contact dermatitis, chrome ulcers, or both. 7 had chrome ulcers, 6 had contact dermatitis and 1 had both. Another 16 (43%) workers had scars suggestive of previous chrome ulcers. Mucosal irritation was present in 57% of the workers. The most common was throat irritation (49%) followed by nasal irritation (41%). Mucosal irritation was more common in hard chrome platers, while skin ulcers and dermatitis were more common in bright chrome platers. Nasal septum perforation was seen in 1 worker. Skin ulceration appeared to be a more specific sign for occupational dermatosis in chrome platers than dermatitis when the prevalence rates were compared to controls. Of the 7 workers with chrome ulcers, only 1 was allergic to chromate. Of the 6 workers with dermatitis, 2 were allergic to chromate and 1 to nickel. The worker with ulceration and dermatitis was negative to chromate and nickel. Irritant factors are therefore important in the aetiology of contact dermatitis in these chrome platers."
1230995,Kato et al. 1988,The structures of katanosins A and B,"1H and 13C NMR studies on katanosin A confirmed the presence of eight usual amino acid residues which were previously deduced by amino acid analysis and suggested the presence of beta-hydroxyaspartic acid, beta-hydroxyleucine and beta-phenylserine residues. These amino acids were isolated and confirmed, including their stereochemistries, by comparison with the respective authentic specimens. Stereochemistries of the usual amino acids were determined by comparing the L-leucylated amino acids with reference compounds by HPLC. Lithium borohydride reduction and chromic acid oxidation of katanosin A and alkali-treated katanosin A elucidated a lactone linkage between the C-terminal Ser and phenylserine residues. Edman degradation on alkali-treated katanosin A clarified the total amino acid sequence. The difference in katanosins A and B was determined to be replacement of Val in A by Ile in B. Thus, the structures of katanosins A and B were elucidated.","The structures of katanosins A and B Abs: 1H and 13C NMR studies on katanosin A confirmed the presence of eight usual amino acid residues which were previously deduced by amino acid analysis and suggested the presence of beta-hydroxyaspartic acid, beta-hydroxyleucine and beta-phenylserine residues. These amino acids were isolated and confirmed, including their stereochemistries, by comparison with the respective authentic specimens. Stereochemistries of the usual amino acids were determined by comparing the L-leucylated amino acids with reference compounds by HPLC. Lithium borohydride reduction and chromic acid oxidation of katanosin A and alkali-treated katanosin A elucidated a lactone linkage between the C-terminal Ser and phenylserine residues. Edman degradation on alkali-treated katanosin A clarified the total amino acid sequence. The difference in katanosins A and B was determined to be replacement of Val in A by Ile in B. Thus, the structures of katanosins A and B were elucidated."
1230994,Mii et al. 1988,Intracytoplasmic crystalloid structures in a malignant fibrous histiocytoma: ultrastructural and cytochemical study,"Crystalloid structures were frequently observed in the cytoplasm of the tumor cells of a malignant fibrous histiocytoma arising in the left leg of a 71-year-old female. These structures were located in the cytoplasm of the fibroblastlike and histiocyte-like tumor cells. The structures consisted of an aggregate of dense granules without unit membrane. Neither glycoproteins nor polysaccharides were detected in these structures on sections stained with chromic acid-phosphotungstic acid or periodic acid-thiocarbohydrazide-silver proteinate. On sections from acrylate-embedded specimens, the structures were easily digested by trypsin and protease but were not sensitive to RNase. Although the significance and origin of these structures remain obscure, the results indicate that the crystalloid structures in the present study are mainly composed of proteinaceous substance.","Intracytoplasmic crystalloid structures in a malignant fibrous histiocytoma: ultrastructural and cytochemical study Abs: Crystalloid structures were frequently observed in the cytoplasm of the tumor cells of a malignant fibrous histiocytoma arising in the left leg of a 71-year-old female. These structures were located in the cytoplasm of the fibroblastlike and histiocyte-like tumor cells. The structures consisted of an aggregate of dense granules without unit membrane. Neither glycoproteins nor polysaccharides were detected in these structures on sections stained with chromic acid-phosphotungstic acid or periodic acid-thiocarbohydrazide-silver proteinate. On sections from acrylate-embedded specimens, the structures were easily digested by trypsin and protease but were not sensitive to RNase. Although the significance and origin of these structures remain obscure, the results indicate that the crystalloid structures in the present study are mainly composed of proteinaceous substance."
1230993,Grote et al. 1988,"Metabolic products of microorganisms. 245. Colabomycins, new antibiotics of the manumycin group from Streptomyces griseoflavus. II. Structure of colabomycin A","The structure of colabomycin A (1) was elucidated by a detailed spectroscopic analysis. Two-dimensional NMR spectroscopy experiments provided assignments of the proton and carbon resonances of the tetraene carboxamide chains occurring in 1. The configurations of eight out of nine double bonds were determined by analysis of their coupling constants. The absolute configurations of C-4 (4S), C-5 (5R) and C-6 (6S) were established from the CD spectra of the parent compound and of 2-(6-oxo-2,4-hexadienoylamino)-5,6-epoxy-1,4-benzoquinone (2), which was obtained from 1 by mild chromic acid oxidation.","Metabolic products of microorganisms. 245. Colabomycins, new antibiotics of the manumycin group from Streptomyces griseoflavus. II. Structure of colabomycin A Abs: The structure of colabomycin A (1) was elucidated by a detailed spectroscopic analysis. Two-dimensional NMR spectroscopy experiments provided assignments of the proton and carbon resonances of the tetraene carboxamide chains occurring in 1. The configurations of eight out of nine double bonds were determined by analysis of their coupling constants. The absolute configurations of C-4 (4S), C-5 (5R) and C-6 (6S) were established from the CD spectra of the parent compound and of 2-(6-oxo-2,4-hexadienoylamino)-5,6-epoxy-1,4-benzoquinone (2), which was obtained from 1 by mild chromic acid oxidation."
1230992,Henly and  Owen 1988,The synthesis of glycine conjugated 3-oxo-bile acids,"The glycine conjugates of the 3-oxo-derivatives of lithocholic, deoxycholic, chenodeoxycholic and cholic acids have been synthesized from their respective parent bile acid using established procedures. The reaction sequence involved oxidation using either chromic acid or silver carbonate--Celite followed by a conjugation step employing the peptide coupling reagent N-ethoxycarbonyl-2-ethoxy-1,2-dihydroquinoline. The final products were obtained in both high yield and purity for use as reference compounds in the analysis of conjugated bile acids in bile and faecal samples by high performance liquid chromatography. Analysis of the prepared 3-oxo-glycobile acids by fast atom bombardment negative ion mass spectrometry, infrared spectroscopy and nuclear magnetic resonance proton spectroscopy is also discussed along with the thin-layer chromatographic properties.","The synthesis of glycine conjugated 3-oxo-bile acids Abs: The glycine conjugates of the 3-oxo-derivatives of lithocholic, deoxycholic, chenodeoxycholic and cholic acids have been synthesized from their respective parent bile acid using established procedures. The reaction sequence involved oxidation using either chromic acid or silver carbonate--Celite followed by a conjugation step employing the peptide coupling reagent N-ethoxycarbonyl-2-ethoxy-1,2-dihydroquinoline. The final products were obtained in both high yield and purity for use as reference compounds in the analysis of conjugated bile acids in bile and faecal samples by high performance liquid chromatography. Analysis of the prepared 3-oxo-glycobile acids by fast atom bombardment negative ion mass spectrometry, infrared spectroscopy and nuclear magnetic resonance proton spectroscopy is also discussed along with the thin-layer chromatographic properties."
1230991,Porubek et al. 1988,"Enantioselective synthesis and preliminary metabolic studies of the optical isomers of 2-n-propyl-4-pentenoic acid, a hepatotoxic metabolite of valproic acid","The enantiomers of 2-n-propyl-4-pentenoic acid (delta 4-VPA), a known hepatotoxic metabolite of 2-n-propylpentanoic acid (valproix acid, VPA), were synthesized with the aid of the chiral auxiliaries (4S)-4-(2-propyl)-2-oxazolidone and (4R,5S)-4-methyl-5-phenyloxazolidone. Alkylation of the n-valeryl derivatives of these oxazolidones with allyl bromide, followed by reductive cleavage and chromic acid oxidation of the product, afforded the desired acids, (R)- and (S)-delta 4-VPA. Greater than 93% enantiomeric excess was achieved in the preparation of both enantiomers. Preliminary studies on the metabolic fate of (R)- and (S)-delta 4-VPA in freshly isolated rat hepatocytes revealed striking differences in the biotransformation of the two enantiomers. Quantification of two major metabolites of delta 4-VPA, viz., 4,5-diOH-VPA gamma-lactone and 2-n-propyl-2(E),4-pentadienoic acid (delta 2E,4-VPA), indicated that larger amounts of the gamma-lactone were formed in incubations utilizing (R)-delta 4-VPA as substrate, whereas production of the diene was greater in incubations with (S)-delta 4-VPA. On the basis of the premise that delta 4-VPA serves as a mechanism-based irreversible inhibitor of enzymes of the fatty acid beta-oxidation complex, these differences in metabolism suggest that the two enantiomers of delta 4-VPA may differ in their hepatotoxic potential.","Enantioselective synthesis and preliminary metabolic studies of the optical isomers of 2-n-propyl-4-pentenoic acid, a hepatotoxic metabolite of valproic acid Abs: The enantiomers of 2-n-propyl-4-pentenoic acid (delta 4-VPA), a known hepatotoxic metabolite of 2-n-propylpentanoic acid (valproix acid, VPA), were synthesized with the aid of the chiral auxiliaries (4S)-4-(2-propyl)-2-oxazolidone and (4R,5S)-4-methyl-5-phenyloxazolidone. Alkylation of the n-valeryl derivatives of these oxazolidones with allyl bromide, followed by reductive cleavage and chromic acid oxidation of the product, afforded the desired acids, (R)- and (S)-delta 4-VPA. Greater than 93% enantiomeric excess was achieved in the preparation of both enantiomers. Preliminary studies on the metabolic fate of (R)- and (S)-delta 4-VPA in freshly isolated rat hepatocytes revealed striking differences in the biotransformation of the two enantiomers. Quantification of two major metabolites of delta 4-VPA, viz., 4,5-diOH-VPA gamma-lactone and 2-n-propyl-2(E),4-pentadienoic acid (delta 2E,4-VPA), indicated that larger amounts of the gamma-lactone were formed in incubations utilizing (R)-delta 4-VPA as substrate, whereas production of the diene was greater in incubations with (S)-delta 4-VPA. On the basis of the premise that delta 4-VPA serves as a mechanism-based irreversible inhibitor of enzymes of the fatty acid beta-oxidation complex, these differences in metabolism suggest that the two enantiomers of delta 4-VPA may differ in their hepatotoxic potential."
1230990,Dutton et al. 1988,Escherichia coli serotype K44: an acidic capsular polysaccharide containing two 2-acetamido-2-deoxyhexoses,"The structure of the capsular polysaccharide from Escherichia coli O8:K44 (A):H- (K44 antigen) has been established using the techniques of methylation, beta-elimination, deamination, and Smith degradation. N.m.r. spectroscopy (13C and 1H) was used extensively to establish the nature of the anomeric linkages of the polysaccharide and of oligosaccharides derived through degradative procedures. The K antigen is comprised of repeating units of the linear tetrasaccharide shown. This acidic polysaccharide represents the first instance of an E. coli K antigen in this series (group A) that has been found to contain two different 2-acetamido-2-deoxyhexoses.","Escherichia coli serotype K44: an acidic capsular polysaccharide containing two 2-acetamido-2-deoxyhexoses Abs: The structure of the capsular polysaccharide from Escherichia coli O8:K44 (A):H- (K44 antigen) has been established using the techniques of methylation, beta-elimination, deamination, and Smith degradation. N.m.r. spectroscopy (13C and 1H) was used extensively to establish the nature of the anomeric linkages of the polysaccharide and of oligosaccharides derived through degradative procedures. The K antigen is comprised of repeating units of the linear tetrasaccharide shown. This acidic polysaccharide represents the first instance of an E. coli K antigen in this series (group A) that has been found to contain two different 2-acetamido-2-deoxyhexoses."
1230988,Lindberg and  Vesterberg 1989,Urinary excretion of chromium in chromeplaters after discontinued exposure,"In a previous study [Lindberg and Vesterberg, 1983a], excretion of chromium in urine (U-Cr) in chromeplaters was proposed for biological monitoring of ongoing exposure. Published reports were found about the decline of U-Cr after discontinued exposure in welders working in chromium-alloyed stainless steel, but not in chromeplaters. In this study, half-times (t1/2) were calculated for ten chromeplaters over a weekend, and for 23 chromeplaters over 31 days vacation. The results suggest that the excretion of chromium can be approximated to a two-compartment model. Estimated from the median values, an initial rapid phase with an assumed t1/2 of 2-3 days is followed by a phase with a t1/2 of approximately a month. Differences between the decline of U-Cr in chromeplaters and welders are discussed.","Urinary excretion of chromium in chromeplaters after discontinued exposure Abs: In a previous study [Lindberg and Vesterberg, 1983a], excretion of chromium in urine (U-Cr) in chromeplaters was proposed for biological monitoring of ongoing exposure. Published reports were found about the decline of U-Cr after discontinued exposure in welders working in chromium-alloyed stainless steel, but not in chromeplaters. In this study, half-times (t1/2) were calculated for ten chromeplaters over a weekend, and for 23 chromeplaters over 31 days vacation. The results suggest that the excretion of chromium can be approximated to a two-compartment model. Estimated from the median values, an initial rapid phase with an assumed t1/2 of 2-3 days is followed by a phase with a t1/2 of approximately a month. Differences between the decline of U-Cr in chromeplaters and welders are discussed."
1230986,Ray et al. 1989,Determination of brodifacoum and bromadiolone residues in rodent and canine liver,"A method to determine residue concentrations of anti-coagulant rodenticides, brodifacoum (BF) and bromadiolone (BD) in liver was developed, using gas chromatography/mass spectrometry. Nine dogs were given 1.1 mg of BF/kg of body weight, PO, in polyethylene glycol 400, one time. Rats were fed BF or BD (via commercial baits) in amounts from 0.28 to 11.25 mg/kg over 1- to 4-day periods. Fresh liver samples were collected at necropsy from all rats and 3 dogs, ground with Na2SO4, and extracted with CHCl3:MeOH (9:1). After evaporation and silica cartridge purification were performed, residues were oxidized with a 0.16M chromic acid solution, and an oxidation product (4-bromobenzoic acid) was partitioned into CHCl3. The methylated derivative (port derivatization with trimethylanilinium hydroxide) was assayed, using gas chromatography/mass spectrometry. Bromadiolone was detected in livers from rats given greater than 6 mg of BD/kg of body weight, but not in livers of rats given 1.25 mg of BD/kg. In contrast, BF was detected (with one exception) in livers from dogs (given 1.1 mg of BF/kg) and from rats given high (11.25 mg of BF/kg) and low (0.28 mg of BF/kg) doses. This protocol, which does not differentiate between BF and BD because of the formation of a common product after chromic acid oxidation, was used to diagnose anticoagulant toxicosis in 3 dogs, 1 human being and 1 llama naturally poisoned.","Determination of brodifacoum and bromadiolone residues in rodent and canine liver Abs: A method to determine residue concentrations of anti-coagulant rodenticides, brodifacoum (BF) and bromadiolone (BD) in liver was developed, using gas chromatography/mass spectrometry. Nine dogs were given 1.1 mg of BF/kg of body weight, PO, in polyethylene glycol 400, one time. Rats were fed BF or BD (via commercial baits) in amounts from 0.28 to 11.25 mg/kg over 1- to 4-day periods. Fresh liver samples were collected at necropsy from all rats and 3 dogs, ground with Na2SO4, and extracted with CHCl3:MeOH (9:1). After evaporation and silica cartridge purification were performed, residues were oxidized with a 0.16M chromic acid solution, and an oxidation product (4-bromobenzoic acid) was partitioned into CHCl3. The methylated derivative (port derivatization with trimethylanilinium hydroxide) was assayed, using gas chromatography/mass spectrometry. Bromadiolone was detected in livers from rats given greater than 6 mg of BD/kg of body weight, but not in livers of rats given 1.25 mg of BD/kg. In contrast, BF was detected (with one exception) in livers from dogs (given 1.1 mg of BF/kg) and from rats given high (11.25 mg of BF/kg) and low (0.28 mg of BF/kg) doses. This protocol, which does not differentiate between BF and BD because of the formation of a common product after chromic acid oxidation, was used to diagnose anticoagulant toxicosis in 3 dogs, 1 human being and 1 llama naturally poisoned."
1230985,Leduc et al. 1989,Multilayered distribution of peptidoglycan in the periplasmic space of Escherichia coli,"When a staining technique using phosphotungstic acid (PTA) in 10% (w/v) chromic acid was applied to cells of Escherichia coli, the periplasmic space was seen as a dark 15-nm-thick layer of uniform appearance and constant width. Our observations are consistent with peptidoglycan being the main material stained. Isolated sacculi as well as purified peptidoglycan (protein free) were also stained by the same procedure, the thickness of the peptidoglycan being 8.8 +/- 1.8 and 6.6 +/- 1.5 nm, respectively. The increased thickness of the PTA-stained layer in stationary phase cells correlated well with the increased thickness of isolated sacculi or purified peptidoglycan and with the increased amount of peptidoglycan in such cells. Thickness measurements on isolated peptidoglycan were compatible with a two to three layer structure for material from exponential phase cells and with a four to five layer structure for that from stationary phase cells. Furthermore, the results indicated an uneven distribution of peptidoglycan material in the periplasmic space, the peptidoglycan spanning the space from the inner to the outer membrane.","Multilayered distribution of peptidoglycan in the periplasmic space of Escherichia coli Abs: When a staining technique using phosphotungstic acid (PTA) in 10% (w/v) chromic acid was applied to cells of Escherichia coli, the periplasmic space was seen as a dark 15-nm-thick layer of uniform appearance and constant width. Our observations are consistent with peptidoglycan being the main material stained. Isolated sacculi as well as purified peptidoglycan (protein free) were also stained by the same procedure, the thickness of the peptidoglycan being 8.8 +/- 1.8 and 6.6 +/- 1.5 nm, respectively. The increased thickness of the PTA-stained layer in stationary phase cells correlated well with the increased thickness of isolated sacculi or purified peptidoglycan and with the increased amount of peptidoglycan in such cells. Thickness measurements on isolated peptidoglycan were compatible with a two to three layer structure for material from exponential phase cells and with a four to five layer structure for that from stationary phase cells. Furthermore, the results indicated an uneven distribution of peptidoglycan material in the periplasmic space, the peptidoglycan spanning the space from the inner to the outer membrane."
1230984,Roth and  Stacey 1989,Cytoplasmic membrane systems involved in bacterium release into soybean nodule cells as studied with two Bradyrhizobium japonicum mutant strains,"Two Bradyrhizobium japonicum, Tn5-induced, mutant strains, ML126 and ML150, were studied. Both induce host cell division to form normal-sized nodules that do not fix nitrogen and whose cells have very few bacteroids (Bar-). Early-infection (15 days post infection) cells have much endoplasmic reticulum (ER), numerous Golgi bodies, and large vacuoles that are probably secondary lysosomes. Later the cytoplasm of the host cells of both are dominated by hundreds of vesicles containing only finely fibrous material and that appear to originate by the degradation of the cell walls of the infection threads; they have been named &quot;infection-thread wall degradation vesicles&quot; (IWDV). Phosphotungstic acid-chromic acid (PACA) staining of thin sections shows that IWDV membranes and the plasma membranes of both the cells and infection threads usually stain quite intensely, while the membranes of other cell organelles do not. The membranes of the few symbiosomes present in the mutants also stain with PACA. This evidence suggests that largely the host-cell plasma membrane gives rise to both the vesicle and symbiosome membranes in these mutants. In cells induced by both mutants, ER appears to be deficient, a finding suggesting that an ER-synthesis signal is involved in the normal release process, that ER synthesis is prerequisite to a normal volume of release, and that insufficient ER can impair symbiosome formation. In the mutant-induced infections, normal lysosomes develop and engulf both symbiosomes and cytoplasmic vesicles, but the retardation of this activity is the probable cause of the cytoplasm becoming overloaded with vesicles.","Cytoplasmic membrane systems involved in bacterium release into soybean nodule cells as studied with two Bradyrhizobium japonicum mutant strains Abs: Two Bradyrhizobium japonicum, Tn5-induced, mutant strains, ML126 and ML150, were studied. Both induce host cell division to form normal-sized nodules that do not fix nitrogen and whose cells have very few bacteroids (Bar-). Early-infection (15 days post infection) cells have much endoplasmic reticulum (ER), numerous Golgi bodies, and large vacuoles that are probably secondary lysosomes. Later the cytoplasm of the host cells of both are dominated by hundreds of vesicles containing only finely fibrous material and that appear to originate by the degradation of the cell walls of the infection threads; they have been named &quot;infection-thread wall degradation vesicles&quot; (IWDV). Phosphotungstic acid-chromic acid (PACA) staining of thin sections shows that IWDV membranes and the plasma membranes of both the cells and infection threads usually stain quite intensely, while the membranes of other cell organelles do not. The membranes of the few symbiosomes present in the mutants also stain with PACA. This evidence suggests that largely the host-cell plasma membrane gives rise to both the vesicle and symbiosome membranes in these mutants. In cells induced by both mutants, ER appears to be deficient, a finding suggesting that an ER-synthesis signal is involved in the normal release process, that ER synthesis is prerequisite to a normal volume of release, and that insufficient ER can impair symbiosome formation. In the mutant-induced infections, normal lysosomes develop and engulf both symbiosomes and cytoplasmic vesicles, but the retardation of this activity is the probable cause of the cytoplasm becoming overloaded with vesicles."
1230983,Kim et al. 1989,CT findings of the nose and paranasal sinuses in chromium intoxication,"We performed computed tomography (CT) of the nose and paranasal sinuses in 21 patients with chromium induced septal perforation or thinning. Twenty patients showed various magnitudes of septal perforation. Twelve of 20 had perforation at the mid portion of the cartilaginous nasal septum. One patient had a sheet-like thinning of septal cartilage. Sixteen patients had mucosal thinning of the nasal conchas. In most cases, unilateral involvement of the inferior concha was seen. Eleven of 21 cases showed paranasal sinus mucosal thickening and one patient had a cyst or polyp in the sinus cavity. The main finding was nodular thickening of mucosa. Septal perforation by inhalation of chromic acid was located in the cartilaginous septum and there was no destruction of the bony septum and wall of the sinuses.","CT findings of the nose and paranasal sinuses in chromium intoxication Abs: We performed computed tomography (CT) of the nose and paranasal sinuses in 21 patients with chromium induced septal perforation or thinning. Twenty patients showed various magnitudes of septal perforation. Twelve of 20 had perforation at the mid portion of the cartilaginous nasal septum. One patient had a sheet-like thinning of septal cartilage. Sixteen patients had mucosal thinning of the nasal conchas. In most cases, unilateral involvement of the inferior concha was seen. Eleven of 21 cases showed paranasal sinus mucosal thickening and one patient had a cyst or polyp in the sinus cavity. The main finding was nodular thickening of mucosa. Septal perforation by inhalation of chromic acid was located in the cartilaginous septum and there was no destruction of the bony septum and wall of the sinuses."
1230982,Alexeeff et al. 1989,Chromium carcinogenicity: California strategies,"Hexavalent chromium was identified by California as a toxic air contaminant (TAC) in January 1986. The California Department of Health Services (CDHS) concurred with the findings of the International Agency for Research on Cancer that there is sufficient evidence to demonstrate the carcinogenicity of chromium in both animals and humans. CDHS did not find any compelling evidence demonstrating the existence of a threshold with respect to chromium carcinogenesis. Experimental data was judged inadequate to assess potential human reproductive risks from ambient exposures. Other health effects were not expected to occur at ambient levels. The theoretically increased lifetime carcinogenic risk from a continuous lifetime exposure to hexavalent chromium fell within the range 12-146 cancer cases per nanogram hexavalent chromium per cubic meter of air per million people exposed, depending on the potency estimate used. The primary sources found to contribute significantly to the risk of exposure were chrome platers, chromic acid anodizing facilities and cooling towers utilizing hexavalent chromium as a corrosion inhibitor. Evaluation of genotoxicity data, animal studies and epidemiological studies indicates that further consideration should be given to the potential carcinogenicity of hexavalent chromium via the oral route.","Chromium carcinogenicity: California strategies Abs: Hexavalent chromium was identified by California as a toxic air contaminant (TAC) in January 1986. The California Department of Health Services (CDHS) concurred with the findings of the International Agency for Research on Cancer that there is sufficient evidence to demonstrate the carcinogenicity of chromium in both animals and humans. CDHS did not find any compelling evidence demonstrating the existence of a threshold with respect to chromium carcinogenesis. Experimental data was judged inadequate to assess potential human reproductive risks from ambient exposures. Other health effects were not expected to occur at ambient levels. The theoretically increased lifetime carcinogenic risk from a continuous lifetime exposure to hexavalent chromium fell within the range 12-146 cancer cases per nanogram hexavalent chromium per cubic meter of air per million people exposed, depending on the potency estimate used. The primary sources found to contribute significantly to the risk of exposure were chrome platers, chromic acid anodizing facilities and cooling towers utilizing hexavalent chromium as a corrosion inhibitor. Evaluation of genotoxicity data, animal studies and epidemiological studies indicates that further consideration should be given to the potential carcinogenicity of hexavalent chromium via the oral route."
1230980,Ohtake et al. 1990,Chromate-resistance in a chromate-reducing strain of Enterobacter cloacae,"Resistance to toxic hexavalent chromium (chromate: CrO4(2)) in Enterobacter cloacae strain HO1, isolated from an activated sludge sample, was investigated under aerobic and anaerobic conditions. Decreased uptake of 51CrO4(2-) in E. cloacae strain HO1 was observed under aerobic conditions, when compared with a standard laboratory E. cloacae strain (IAM 1624). Under anaerobic conditions E. cloacae strain HO1 was able to reduce hexavalent chromium to the less toxic trivalent form. When E. clocacae strain HO1 was grown with nitrate anaerobically, the cells were observed to lose simultaneously their chromate-reducing ability and chromate-resistance under anaerobic conditions.","Chromate-resistance in a chromate-reducing strain of Enterobacter cloacae Abs: Resistance to toxic hexavalent chromium (chromate: CrO4(2)) in Enterobacter cloacae strain HO1, isolated from an activated sludge sample, was investigated under aerobic and anaerobic conditions. Decreased uptake of 51CrO4(2-) in E. cloacae strain HO1 was observed under aerobic conditions, when compared with a standard laboratory E. cloacae strain (IAM 1624). Under anaerobic conditions E. cloacae strain HO1 was able to reduce hexavalent chromium to the less toxic trivalent form. When E. clocacae strain HO1 was grown with nitrate anaerobically, the cells were observed to lose simultaneously their chromate-reducing ability and chromate-resistance under anaerobic conditions."
1230979,Dutton et al. 1990,The structure of Escherichia coli K31 antigen,"The capsular polysaccharide of Escherichia coli K31 has been found by methylation analysis and n.m.r. spectroscopy to be based on the hexasaccharide shown. The sequence of the repeating unit was deduced from the combined results of beta-elimination, lithium-ethylenediamine degradation, and hydrogen-fluoride and selective hydrolyses. The nature of the anomeric linkages, established by chromic acid oxidation, was confirmed by 1H-coupled 13C-n.m.r. spectroscopy. Two dimensional n.m.r. studies on a low molecular weight polymer obtained by bacteriophage depolymerization are also reported. (formula; see text)","The structure of Escherichia coli K31 antigen Abs: The capsular polysaccharide of Escherichia coli K31 has been found by methylation analysis and n.m.r. spectroscopy to be based on the hexasaccharide shown. The sequence of the repeating unit was deduced from the combined results of beta-elimination, lithium-ethylenediamine degradation, and hydrogen-fluoride and selective hydrolyses. The nature of the anomeric linkages, established by chromic acid oxidation, was confirmed by 1H-coupled 13C-n.m.r. spectroscopy. Two dimensional n.m.r. studies on a low molecular weight polymer obtained by bacteriophage depolymerization are also reported. (formula; see text)"
1230978,Nies et al. 1990,Nucleotide sequence and expression of a plasmid-encoded chromate resistance determinant from Alcaligenes eutrophus,"The nucleotide sequence of the 2.6-kilobase pair (kb) EcoRI fragment encoding chromate resistance (Chrr) on plasmid pMOL28 in Alcaligenes eutrophus was determined. Three open reading frames were assigned to three polypeptides which were expressed from this determinant in Escherichia coli under the control of a phage T7 transcription promoter. When the roles of the polypeptides and open reading frames were analyzed with deletion derivatives of the 2.6-kilobase fragment, the membrane-bound ChrA (401 amino acids) and ChrB (196 amino acids) polypeptides were essential for inducible chromate resistance and reduced accumulation of chromate, while the third open reading frame was not needed.","Nucleotide sequence and expression of a plasmid-encoded chromate resistance determinant from Alcaligenes eutrophus Abs: The nucleotide sequence of the 2.6-kilobase pair (kb) EcoRI fragment encoding chromate resistance (Chrr) on plasmid pMOL28 in Alcaligenes eutrophus was determined. Three open reading frames were assigned to three polypeptides which were expressed from this determinant in Escherichia coli under the control of a phage T7 transcription promoter. When the roles of the polypeptides and open reading frames were analyzed with deletion derivatives of the 2.6-kilobase fragment, the membrane-bound ChrA (401 amino acids) and ChrB (196 amino acids) polypeptides were essential for inducible chromate resistance and reduced accumulation of chromate, while the third open reading frame was not needed."
1230977,Malinin et al. 1990,Direct oxidation of lymphocytes by chromic acid does not induce blastogenesis,"Blastogenic and cytotoxic effects of hexavalent chromium were evaluated by direct, 2 and 20 min oxidation of lymphocytes by 10.0 to 0.0005 mM CrO3 at 0 degrees C. Oxidized cells exhibited concentration-dependent cytotoxicity and the inhibition of tritiated thymidine incorporation rates. When lymphocytes were oxidized first by 1.0 mM periodic acid (H5IO6) and thereafter by 1.0 mM CrO3, the viability and [3H]-TdR incorporation rates of sequentially oxidized cells were identical to the corresponding indicators of lymphocytes oxidized only by CrO3. The reversal of the oxidation sequence restored [3H]-TdR incorporation to control levels and increased cell survival. It is therefore concluded that direct interaction of hexavalent CrO3 with plasma membrane of lymphocytes results in concentration-dependent cytotoxicity and the inhibition of [3H]-TdR incorporation, but it does not induce blastogenesis.","Direct oxidation of lymphocytes by chromic acid does not induce blastogenesis Abs: Blastogenic and cytotoxic effects of hexavalent chromium were evaluated by direct, 2 and 20 min oxidation of lymphocytes by 10.0 to 0.0005 mM CrO3 at 0 degrees C. Oxidized cells exhibited concentration-dependent cytotoxicity and the inhibition of tritiated thymidine incorporation rates. When lymphocytes were oxidized first by 1.0 mM periodic acid (H5IO6) and thereafter by 1.0 mM CrO3, the viability and [3H]-TdR incorporation rates of sequentially oxidized cells were identical to the corresponding indicators of lymphocytes oxidized only by CrO3. The reversal of the oxidation sequence restored [3H]-TdR incorporation to control levels and increased cell survival. It is therefore concluded that direct interaction of hexavalent CrO3 with plasma membrane of lymphocytes results in concentration-dependent cytotoxicity and the inhibition of [3H]-TdR incorporation, but it does not induce blastogenesis."
1230975,Irie et al. 1990,"Ceramide dihexosides from the spermatozoa of the starfish, Asterias amurensis, consist of gentiobiosyl- cellobiosyl-, and lactosylceramide","Ceramide dihexoside was obtained from the spermatozoa of the starfish, Asterias amurensis. Gas-liquid chromatography of the methanolysate to determine the sugar composition of the lipid demonstrated an unequal ratio of glucose and galactose, implying that two or more glycolipids are present. They were separated by thin-layer chromatography on a borate-impregnated plate into two bands. From the results of methylation analysis and chromic acid oxidation, one was determined to be lactosylceramide, while the other was suggested to be a mixture of two diglucosylceramides: gentiobiosylceramide (Glc beta 1-6Glc beta 1-1Cer) and cellobiosylceramide (Glc beta 1-4Glc beta 1-1Cer). The molar ratio of gentiobiosyl-, cellobiosyl-, and lactosylceramide was estimated to be 0.7 : 0.3 : 1.0. Ceramide dihexosides obtained from another batch of the spermatozoa, collected at the same place in a different year, consisted almost exclusively of gentiobiosylceramide as confirmed by proton-nuclear magnetic resonance spectroscopy and fast-atom bombardment mass-spectrometry. The fatty acid compositions of these glycolipids were similar and the main acids were 14h:0, 15h:0, 16h:0, 18h:0, and 24h:1 (constituting more than 80% of the total acids). The long-chain base compositions were qualitatively similar and the major constituents were commonly d18:2, d18:3, d19:3, d22:2, and t22:1. Lactosylceramide was rich in t22:1, while diglucosylceramides were rich in d22:2.","Ceramide dihexosides from the spermatozoa of the starfish, Asterias amurensis, consist of gentiobiosyl- cellobiosyl-, and lactosylceramide Abs: Ceramide dihexoside was obtained from the spermatozoa of the starfish, Asterias amurensis. Gas-liquid chromatography of the methanolysate to determine the sugar composition of the lipid demonstrated an unequal ratio of glucose and galactose, implying that two or more glycolipids are present. They were separated by thin-layer chromatography on a borate-impregnated plate into two bands. From the results of methylation analysis and chromic acid oxidation, one was determined to be lactosylceramide, while the other was suggested to be a mixture of two diglucosylceramides: gentiobiosylceramide (Glc beta 1-6Glc beta 1-1Cer) and cellobiosylceramide (Glc beta 1-4Glc beta 1-1Cer). The molar ratio of gentiobiosyl-, cellobiosyl-, and lactosylceramide was estimated to be 0.7 : 0.3 : 1.0. Ceramide dihexosides obtained from another batch of the spermatozoa, collected at the same place in a different year, consisted almost exclusively of gentiobiosylceramide as confirmed by proton-nuclear magnetic resonance spectroscopy and fast-atom bombardment mass-spectrometry. The fatty acid compositions of these glycolipids were similar and the main acids were 14h:0, 15h:0, 16h:0, 18h:0, and 24h:1 (constituting more than 80% of the total acids). The long-chain base compositions were qualitatively similar and the major constituents were commonly d18:2, d18:3, d19:3, d22:2, and t22:1. Lactosylceramide was rich in t22:1, while diglucosylceramides were rich in d22:2."
1230974,Kortenkamp et al. 1990,The DNA cleavage induced by a chromium(V) complex and by chromate and glutathione is mediated by activated oxygen species,"The number of strand breaks induced by the combination of chromate and glutathione (GSH) in PM2 DNA was effectively reduced upon addition of the hydroxyl radical scavengers dimethyl sulphoxide (DMSO), formate and benzoate. Administration of catalase also led to a depression of DNA degradation whereas superoxide dismutase (SOD) had very little influence. Essentially the same results were obtained in experiments employing a chromium(V) complex Na4(GSH)4Cr.8H20, which is an intermediate chromium species isolated from the reduction of chromate by glutathione. DNA cleavage was dependent on the presence of iron (FeCl3). When compared with the number of breaks produced by FeCl3 and GSH alone, chromate stimulated the generation of single-strand breaks. These findings suggest that hydroxyl radicals are one ultimate DNA cleaving agent in both reactions. A reaction scheme for the production of hydroxyl radicals is proposed.","The DNA cleavage induced by a chromium(V) complex and by chromate and glutathione is mediated by activated oxygen species Abs: The number of strand breaks induced by the combination of chromate and glutathione (GSH) in PM2 DNA was effectively reduced upon addition of the hydroxyl radical scavengers dimethyl sulphoxide (DMSO), formate and benzoate. Administration of catalase also led to a depression of DNA degradation whereas superoxide dismutase (SOD) had very little influence. Essentially the same results were obtained in experiments employing a chromium(V) complex Na4(GSH)4Cr.8H20, which is an intermediate chromium species isolated from the reduction of chromate by glutathione. DNA cleavage was dependent on the presence of iron (FeCl3). When compared with the number of breaks produced by FeCl3 and GSH alone, chromate stimulated the generation of single-strand breaks. These findings suggest that hydroxyl radicals are one ultimate DNA cleaving agent in both reactions. A reaction scheme for the production of hydroxyl radicals is proposed."
1230973,Costa 1990,Analysis of DNA-protein complexes induced by chemical carcinogens,"DNA-protein complexes induced in intact cells by chromate have been isolated and compared with those formed by other agents such as cis-platinum. Actin has been identified as one of the major proteins that is complexed to the DNA by chromate based upon a number of criteria including, a molecular weight and isoelectric point identical to actin, positive reaction with actin polyclonal antibody, and proteolytic mapping. Chromate and cis-platinum both complex proteins of very similar molecular weight and isoelectric points and these complexes can be disrupted by exposure to chelating or reducing agents. These results suggest that the metal itself is participating in rather than catalyzing the formation of a DNA-protein complex. An antiserum which was raised to chromate-induced DNA-protein complexes reacted primarily with a 97,000 protein that could not be detected by silver staining. Western blots and slot blots were utilized to detect p97 DNA-protein complexes formed by cis-platinum, UV, formaldehyde, and chromate. Other work in this area, involving studying whether DNA-protein complexes are formed in actively transcribed DNA compared with genetically inactive DNA, is discussed. Methods to detect DNA-protein complexes, the stability and repair of these lesions, and characterization of DNA-protein complexes are reviewed. Nuclear matrix proteins have been identified as a major substrate for the formation of DNA-protein complexes and these findings are also reviewed.","Analysis of DNA-protein complexes induced by chemical carcinogens Abs: DNA-protein complexes induced in intact cells by chromate have been isolated and compared with those formed by other agents such as cis-platinum. Actin has been identified as one of the major proteins that is complexed to the DNA by chromate based upon a number of criteria including, a molecular weight and isoelectric point identical to actin, positive reaction with actin polyclonal antibody, and proteolytic mapping. Chromate and cis-platinum both complex proteins of very similar molecular weight and isoelectric points and these complexes can be disrupted by exposure to chelating or reducing agents. These results suggest that the metal itself is participating in rather than catalyzing the formation of a DNA-protein complex. An antiserum which was raised to chromate-induced DNA-protein complexes reacted primarily with a 97,000 protein that could not be detected by silver staining. Western blots and slot blots were utilized to detect p97 DNA-protein complexes formed by cis-platinum, UV, formaldehyde, and chromate. Other work in this area, involving studying whether DNA-protein complexes are formed in actively transcribed DNA compared with genetically inactive DNA, is discussed. Methods to detect DNA-protein complexes, the stability and repair of these lesions, and characterization of DNA-protein complexes are reviewed. Nuclear matrix proteins have been identified as a major substrate for the formation of DNA-protein complexes and these findings are also reviewed."
1230972,Terrill and  Gowar 1990,"Chromic acid burns; beware, be aggressive, be watchful",Two cases involving the development of systemic toxicity and prolonged wound healing in small percentage area burns to chromic acid are reported. The treatment of chromic acid burns is reviewed and a protocol of management suggested.,"Chromic acid burns; beware, be aggressive, be watchful Abs: Two cases involving the development of systemic toxicity and prolonged wound healing in small percentage area burns to chromic acid are reported. The treatment of chromic acid burns is reviewed and a protocol of management suggested."
1230970,Appenroth et al. 1991,Chromate nephrotoxicity in developing rats. Significance of Cr(VI) reduction in rat kidney tissue,"Chromate reduction was studied in 9000 x g supernatant of renal tissue. It was shown that GSH plays an important role. Additionally, heat-sensitive factor(s) seem to be involved. Age differences in chromate nephrotoxicity parallel differences in chromate reduction in vitro. The lower reductive activity of young rats can be raised to adult values by GSH-addition. Fasting reduces GSH concentration, as well as chromate nephrotoxicity, in vivo.","Chromate nephrotoxicity in developing rats. Significance of Cr(VI) reduction in rat kidney tissue Abs: Chromate reduction was studied in 9000 x g supernatant of renal tissue. It was shown that GSH plays an important role. Additionally, heat-sensitive factor(s) seem to be involved. Age differences in chromate nephrotoxicity parallel differences in chromate reduction in vitro. The lower reductive activity of young rats can be raised to adult values by GSH-addition. Fasting reduces GSH concentration, as well as chromate nephrotoxicity, in vivo."
1230969,Cervantes 1991,Bacterial interactions with chromate,"Hexavalent chromium compounds (chromates and dichromates) are highly toxic and are considered as mutagens and carcinogens. These compounds are discharged frequently to the environment as a result of diverse industrial processes. Some microorganisms are able to reduce hexavalent chromium to the less toxic trivalent form. Chromate pollution has promoted the selection of bacterial strains possessing chromate resistance determinants, usually carried by plasmids. Strains combining both abilities, i.e. resistance to and reduction of chromate, are potentially useful for detoxifying chromate polluted waste waters.","Bacterial interactions with chromate Abs: Hexavalent chromium compounds (chromates and dichromates) are highly toxic and are considered as mutagens and carcinogens. These compounds are discharged frequently to the environment as a result of diverse industrial processes. Some microorganisms are able to reduce hexavalent chromium to the less toxic trivalent form. Chromate pollution has promoted the selection of bacterial strains possessing chromate resistance determinants, usually carried by plasmids. Strains combining both abilities, i.e. resistance to and reduction of chromate, are potentially useful for detoxifying chromate polluted waste waters."
1230968,Lees 1991,Chromium and disease: review of epidemiologic studies with particular reference to etiologic information provided by measures of exposure,"Dozens of epidemiologic studies have been conducted since the late 1940s in an attempt to elucidate the relationship between exposure to chromium compounds and increased rates of certain cancers observed in several industries. The relationship between employment in industries producing chromium compounds from chromite ore and lung cancer has been well established in numerous studies. The relationship between exposure to certain chromium-based pigments and chromic acid and lung cancer, although not as strong, is fairly well accepted. The data concerning emissions from stainless-steel manufacturing and disease are contradictory. Although individual studies have indicated excesses of gastrointestinal and occasionally other cancers in these industries, results are not consistent and not universally accepted. There is general agreement that chromite ore does not have an associated risk of cancer. Although the chromium compound (or compounds) responsible for disease have yet to be identified, there is general agreement that hexavalent species are responsible for these diseases and that the trivalent species are not. Hypotheses about the carcinogenicity of specific chromium compounds generally relate to their solubility in body fluids. These hypotheses, however, have generally been produced as a result of toxicologic, not epidemiologic, investigation. Well-designed epidemiologic studies incorporating detailed assessments of worker exposures have the potential to help elucidate causality, identify specific carcinogenic compounds, and quantify risk in humans, eliminating the need to extrapolate from animal data. Although the need for exposure data crucial to this effort was identified in the earliest epidemiologic studies of chromium, such studies have not been conducted. As a result, little more is known today about the relationship between this chemical and disease in humans than was known 40 years ago.","Chromium and disease: review of epidemiologic studies with particular reference to etiologic information provided by measures of exposure Abs: Dozens of epidemiologic studies have been conducted since the late 1940s in an attempt to elucidate the relationship between exposure to chromium compounds and increased rates of certain cancers observed in several industries. The relationship between employment in industries producing chromium compounds from chromite ore and lung cancer has been well established in numerous studies. The relationship between exposure to certain chromium-based pigments and chromic acid and lung cancer, although not as strong, is fairly well accepted. The data concerning emissions from stainless-steel manufacturing and disease are contradictory. Although individual studies have indicated excesses of gastrointestinal and occasionally other cancers in these industries, results are not consistent and not universally accepted. There is general agreement that chromite ore does not have an associated risk of cancer. Although the chromium compound (or compounds) responsible for disease have yet to be identified, there is general agreement that hexavalent species are responsible for these diseases and that the trivalent species are not. Hypotheses about the carcinogenicity of specific chromium compounds generally relate to their solubility in body fluids. These hypotheses, however, have generally been produced as a result of toxicologic, not epidemiologic, investigation. Well-designed epidemiologic studies incorporating detailed assessments of worker exposures have the potential to help elucidate causality, identify specific carcinogenic compounds, and quantify risk in humans, eliminating the need to extrapolate from animal data. Although the need for exposure data crucial to this effort was identified in the earliest epidemiologic studies of chromium, such studies have not been conducted. As a result, little more is known today about the relationship between this chemical and disease in humans than was known 40 years ago."
1230967,Bendtsen and  Hansen 1991,Spectrophotometric flow injection determination of trace amounts of thiocyanate based on its reaction with 2-(5-bromo-2-pyridylazo)-5-diethylaminophenol and dichromate: assay of the thiocyanate level in saliva from smokers and non-smokers,"A simple and very sensitive spectrophotometric flow injection (FI) procedure for the determination of trace amounts of thiocyanate is described. The proposed method is based on the reaction between thiocyanate and 2-(5-bromo-2-pyridylazo)-5-diethylaminophenol, which, in 2 mol dm-3 acidic media in the presence of a strong oxidizing agent, produces an intensely coloured product. Several oxidants are potentially applicable, but it is shown that dichromate is preferable. As the reaction product formed is unstable and the signal inherently is recorded on a high background level, it is demonstrated that FI constitutes an ideal method in order to monitor reproducibly and repeatedly the kinetically transient signal that is obtained. Based on optimization by a factorial experimental design, the detection limit of the procedure was found to be 3.5 mumol dm-3, and the standard deviation between samples was 0.16 mumol dm-3. No significant interferences were observed; a 1000-fold excess of cyanide could readily be tolerated within the experimental error. With a sample volume of 50 microliters being injected, the sampling frequency was 60 samples h-1. The system was tested with saliva samples from non-smokers and smokers, and the results show that it is possible to distinguish between these two categories of individuals. As an added benefit, the detection limit of the analytical procedure allows the samples to be diluted 100-fold, so that centrifugation for 5 min is the only preliminary sample preparation that is necessary.","Spectrophotometric flow injection determination of trace amounts of thiocyanate based on its reaction with 2-(5-bromo-2-pyridylazo)-5-diethylaminophenol and dichromate: assay of the thiocyanate level in saliva from smokers and non-smokers Abs: A simple and very sensitive spectrophotometric flow injection (FI) procedure for the determination of trace amounts of thiocyanate is described. The proposed method is based on the reaction between thiocyanate and 2-(5-bromo-2-pyridylazo)-5-diethylaminophenol, which, in 2 mol dm-3 acidic media in the presence of a strong oxidizing agent, produces an intensely coloured product. Several oxidants are potentially applicable, but it is shown that dichromate is preferable. As the reaction product formed is unstable and the signal inherently is recorded on a high background level, it is demonstrated that FI constitutes an ideal method in order to monitor reproducibly and repeatedly the kinetically transient signal that is obtained. Based on optimization by a factorial experimental design, the detection limit of the procedure was found to be 3.5 mumol dm-3, and the standard deviation between samples was 0.16 mumol dm-3. No significant interferences were observed; a 1000-fold excess of cyanide could readily be tolerated within the experimental error. With a sample volume of 50 microliters being injected, the sampling frequency was 60 samples h-1. The system was tested with saliva samples from non-smokers and smokers, and the results show that it is possible to distinguish between these two categories of individuals. As an added benefit, the detection limit of the analytical procedure allows the samples to be diluted 100-fold, so that centrifugation for 5 min is the only preliminary sample preparation that is necessary."
1230964,Lin 1992,[Chronic chromate intoxication with renal tubular damage--report of a case],"A 46-year-old male chromium plating worker visited our hospital due to rhinorrhea, sneezing and cough with blood-tinged sputum for more than 10 years. He also had skin ulceration and chronic dermatitis on both hands Medical therapy was inefficient. Physical examinations revealed nasal septum perforation, severe inflammation of the nasopharynx cavity, and eczema of both hands. Laboratory investigations showed significant tubule proteinuria, enzymuria, hypercalciuria, etc. It is evident that renal tube damage was present in this patient. The blood chromium level was 25 ng/mL, and the 24-hour urine chromium excretion level was 2.8 mg/day. A pulmonary function test showed reduced functional residual capacity (FRC), which may be due to either long-term smoking or chromate acid exposure. To our knowledge this is the first case of renal tubal damage induced by chronic chromate intoxication Taiwan. Further evaluation of the occupational safety and health of chromium plating workers is needed on this island.","[Chronic chromate intoxication with renal tubular damage--report of a case] Abs: A 46-year-old male chromium plating worker visited our hospital due to rhinorrhea, sneezing and cough with blood-tinged sputum for more than 10 years. He also had skin ulceration and chronic dermatitis on both hands Medical therapy was inefficient. Physical examinations revealed nasal septum perforation, severe inflammation of the nasopharynx cavity, and eczema of both hands. Laboratory investigations showed significant tubule proteinuria, enzymuria, hypercalciuria, etc. It is evident that renal tube damage was present in this patient. The blood chromium level was 25 ng/mL, and the 24-hour urine chromium excretion level was 2.8 mg/day. A pulmonary function test showed reduced functional residual capacity (FRC), which may be due to either long-term smoking or chromate acid exposure. To our knowledge this is the first case of renal tubal damage induced by chronic chromate intoxication Taiwan. Further evaluation of the occupational safety and health of chromium plating workers is needed on this island."
1230963,Mappus et al. 1992,Synthesis and characterization by 1H and 13C nuclear magnetic resonance spectroscopy of 17 alpha-hexanoic derivatives of 5 alpha-dihydrotestosterone and testosterone,"The synthesis and characterization of 17 alpha-(6'-hexanoic acid) derivatives of 5 alpha-dihydrotestosterone and testosterone, useful as ligands for affinity chromatography purification or as precursors for affinity-labeling of androgen-binding proteins, is described. Alkynylation of 3-ethylenedioxy-, 3 beta-hydroxy-, and 3 beta,5-dihydroxy-5 alpha-androstan-17-one precursors with the potassium derivative of 5-hexyn-1-ol led to the corresponding 17 alpha-(6'-hydroxyhex-1'-ynyl) derivatives, which were hydrogenated over 10% Pt-C catalyst to give 17 alpha-(6'-hydroxyhexyl) derivatives. Chromic acid oxidation of the primary hydroxy group of the 3-ethylenedioxy-17-hexyl intermediate into carboxylic acid followed by acid cleavage of the 3-ketal group gave 17 alpha-(5'-carboxypentyl)-5 alpha-dihydrotestosterone, which was also obtained directly by chromic acid oxidation of the 3 beta-hydroxy intermediate. Chromic acid oxidation of the primary hydroxy group of the 3 beta,5 alpha-dihydroxy precursor resulted in a 5 alpha-hydroxy-3-oxo intermediate, which was dehydrated to give 17 alpha-(5'-carboxypentyl)testosterone. The 17 alpha configuration of these derivatives and of synthetic precursors was established by comparing their molecular rotations and their 1H and 13C nuclear magnetic resonance (NMR) spectra including solvent effects, with data reported for 17 alpha- or 17 beta-substituted steroid analogs as well as with 1H and 13C NMR reference data recorded in this work for 17 alpha-ethynyltestosterone, 17 alpha-ethynyl-19-nortestosterone, 17 alpha-ethyl-19-nortestosterone, 17 alpha-methyltestosterone, and 17 alpha-methyl-5 alpha-dihydrotestosterone.","Synthesis and characterization by 1H and 13C nuclear magnetic resonance spectroscopy of 17 alpha-hexanoic derivatives of 5 alpha-dihydrotestosterone and testosterone Abs: The synthesis and characterization of 17 alpha-(6'-hexanoic acid) derivatives of 5 alpha-dihydrotestosterone and testosterone, useful as ligands for affinity chromatography purification or as precursors for affinity-labeling of androgen-binding proteins, is described. Alkynylation of 3-ethylenedioxy-, 3 beta-hydroxy-, and 3 beta,5-dihydroxy-5 alpha-androstan-17-one precursors with the potassium derivative of 5-hexyn-1-ol led to the corresponding 17 alpha-(6'-hydroxyhex-1'-ynyl) derivatives, which were hydrogenated over 10% Pt-C catalyst to give 17 alpha-(6'-hydroxyhexyl) derivatives. Chromic acid oxidation of the primary hydroxy group of the 3-ethylenedioxy-17-hexyl intermediate into carboxylic acid followed by acid cleavage of the 3-ketal group gave 17 alpha-(5'-carboxypentyl)-5 alpha-dihydrotestosterone, which was also obtained directly by chromic acid oxidation of the 3 beta-hydroxy intermediate. Chromic acid oxidation of the primary hydroxy group of the 3 beta,5 alpha-dihydroxy precursor resulted in a 5 alpha-hydroxy-3-oxo intermediate, which was dehydrated to give 17 alpha-(5'-carboxypentyl)testosterone. The 17 alpha configuration of these derivatives and of synthetic precursors was established by comparing their molecular rotations and their 1H and 13C nuclear magnetic resonance (NMR) spectra including solvent effects, with data reported for 17 alpha- or 17 beta-substituted steroid analogs as well as with 1H and 13C NMR reference data recorded in this work for 17 alpha-ethynyltestosterone, 17 alpha-ethynyl-19-nortestosterone, 17 alpha-ethyl-19-nortestosterone, 17 alpha-methyltestosterone, and 17 alpha-methyl-5 alpha-dihydrotestosterone."
1230962,Kubo et al. 1992,"A novel ceramide trihexoside from the eggs of the sea urchin, Hemicentrotus pulcherrimus","Glucosylceramide (Glc beta 1-1Cer) and a novel ceramide trihexoside (Gal beta 1-6Gal beta 1-6Glc beta 1-1Cer) were purified from the eggs of the sea urchin, Hemicentrotus pulcherrimus. Their chemical structures were determined by gas-liquid chromatography, methylation analysis, chromic acid oxidation, enzymatic hydrolysis, enzyme-linked immunosorbent assay, fast atom bombardment mass spectrometry, and proton nuclear magnetic resonance spectroscopy. The ceramide trihexoside has a novel carbohydrate structure, and its core structure, Gal beta 1-6Glc, is also novel. The ceramide moieties of these glycolipids are almost identical. Two fatty acids, 22:1 and 22h:1, constitute more than 80% of the total acids. Long-chain bases are all phytosphingosine, approximately 90% of which is n-t18:0. The finding of melibiosylceramide (Gal alpha 1-6Glc beta 1-1Cer) from the eggs of another sea urchin species [Kubo, H. et al. (1988) J. Biochem. 104, 755-760] and the present finding of the novel ceramide trihexoside suggest that there are a variety of unique sugar structures in sea urchin glycosphingolipids.","A novel ceramide trihexoside from the eggs of the sea urchin, Hemicentrotus pulcherrimus Abs: Glucosylceramide (Glc beta 1-1Cer) and a novel ceramide trihexoside (Gal beta 1-6Gal beta 1-6Glc beta 1-1Cer) were purified from the eggs of the sea urchin, Hemicentrotus pulcherrimus. Their chemical structures were determined by gas-liquid chromatography, methylation analysis, chromic acid oxidation, enzymatic hydrolysis, enzyme-linked immunosorbent assay, fast atom bombardment mass spectrometry, and proton nuclear magnetic resonance spectroscopy. The ceramide trihexoside has a novel carbohydrate structure, and its core structure, Gal beta 1-6Glc, is also novel. The ceramide moieties of these glycolipids are almost identical. Two fatty acids, 22:1 and 22h:1, constitute more than 80% of the total acids. Long-chain bases are all phytosphingosine, approximately 90% of which is n-t18:0. The finding of melibiosylceramide (Gal alpha 1-6Glc beta 1-1Cer) from the eggs of another sea urchin species [Kubo, H. et al. (1988) J. Biochem. 104, 755-760] and the present finding of the novel ceramide trihexoside suggest that there are a variety of unique sugar structures in sea urchin glycosphingolipids."
1230960,Finley et al. 1992,An alternative to the USEPA's proposed inhalation reference concentrations for hexavalent and trivalent chromium,"The passage of the Clean Air Act Amendment of 1990 reflects a growing public concern over human exposure to air toxics. The EPA is currently identifying inhalation reference concentrations (RfCs) to be used as risk criteria for determining whether existing or predicted ambient levels of chemicals are above acceptable concentrations. This paper evaluates the risk assessment methods used by the EPA to develop the recently proposed RfC (0.002 micrograms/m3) for both trivalent chromium [Cr(III)] and hexavalent chromium [Cr(VI)]. Based on our evaluation, these RfC values do not appear to have been developed in accordance with standard Agency procedures or classic toxicology methods for setting RfCs. In particular, the &quot;key&quot; study used by the EPA [E. Lindberg and G. Hedenstierna (1983) Arch. Environ. Health 38, 367-374] as the basis for their proposal is not appropriate because it examined only the effects of exposure to chromic acid mist [Cr(VI)], even though most environmental exposure is to Cr(VI) and Cr(III) as a dust. The health hazards of Cr(VI) as an acid mist are significantly different from those associated with Cr(VI) as a dust. Further, the EPA's key study did not evaluate exposure to Cr(III), the toxicity of which is significantly different from both particulate Cr(VI) and chromic acid mist. Finally, the uncertainty factors used to account for data gaps were unusually high, thus providing RfC values equal to or below most naturally occurring environmental levels and standard analytical limits of detection. In this paper, we propose alternative RfCs for Cr(VI) as chromic acid mist and for Cr(VI) as a dust. Based on the Lindberg and Hedenstierna study, we derived an RfC of approximately 0.12 micrograms/m3 for chromic acid mist. An RfC of 1.2 micrograms/m3 is recommended for particulate Cr(VI) based on animal studies that evaluate long-term inhalation exposure to Cr(VI) dust. Due to its low toxicity, an RfC for Cr(III) is not warranted.","An alternative to the USEPA's proposed inhalation reference concentrations for hexavalent and trivalent chromium Abs: The passage of the Clean Air Act Amendment of 1990 reflects a growing public concern over human exposure to air toxics. The EPA is currently identifying inhalation reference concentrations (RfCs) to be used as risk criteria for determining whether existing or predicted ambient levels of chemicals are above acceptable concentrations. This paper evaluates the risk assessment methods used by the EPA to develop the recently proposed RfC (0.002 micrograms/m3) for both trivalent chromium [Cr(III)] and hexavalent chromium [Cr(VI)]. Based on our evaluation, these RfC values do not appear to have been developed in accordance with standard Agency procedures or classic toxicology methods for setting RfCs. In particular, the &quot;key&quot; study used by the EPA [E. Lindberg and G. Hedenstierna (1983) Arch. Environ. Health 38, 367-374] as the basis for their proposal is not appropriate because it examined only the effects of exposure to chromic acid mist [Cr(VI)], even though most environmental exposure is to Cr(VI) and Cr(III) as a dust. The health hazards of Cr(VI) as an acid mist are significantly different from those associated with Cr(VI) as a dust. Further, the EPA's key study did not evaluate exposure to Cr(III), the toxicity of which is significantly different from both particulate Cr(VI) and chromic acid mist. Finally, the uncertainty factors used to account for data gaps were unusually high, thus providing RfC values equal to or below most naturally occurring environmental levels and standard analytical limits of detection. In this paper, we propose alternative RfCs for Cr(VI) as chromic acid mist and for Cr(VI) as a dust. Based on the Lindberg and Hedenstierna study, we derived an RfC of approximately 0.12 micrograms/m3 for chromic acid mist. An RfC of 1.2 micrograms/m3 is recommended for particulate Cr(VI) based on animal studies that evaluate long-term inhalation exposure to Cr(VI) dust. Due to its low toxicity, an RfC for Cr(III) is not warranted."
1230958,Solaja et al. 1994,Oxidation of steroidal 5-en-3 beta-ols with Jones reagent in ether,"The two-phase oxidation of steroidal 5-en-3 beta-ol (via 5-en-3-ones) into corresponding 4-en-3,6-diones in diethyl ether with Jones reagent was investigated. It was found that the system Jones reagent/diethyl ether enables short reaction times and easy isolation of the obtained products. The exclusive abstraction of 4 alpha-hydrogen during oxidation, together with molecular mechanics (MM2), and semiempirical (PM3) calculations, suggest that boat conformation of ring A precedes the formation of corresponding radicals (or cations).","Oxidation of steroidal 5-en-3 beta-ols with Jones reagent in ether Abs: The two-phase oxidation of steroidal 5-en-3 beta-ol (via 5-en-3-ones) into corresponding 4-en-3,6-diones in diethyl ether with Jones reagent was investigated. It was found that the system Jones reagent/diethyl ether enables short reaction times and easy isolation of the obtained products. The exclusive abstraction of 4 alpha-hydrogen during oxidation, together with molecular mechanics (MM2), and semiempirical (PM3) calculations, suggest that boat conformation of ring A precedes the formation of corresponding radicals (or cations)."
1230957,Mwaura et al. 1994,Sample preparation technique for iodine determination in urine and water samples,"A simple method for iodine determination in urine and water samples is presented. After digestion of the sample with chromic acid, the iodate produced was converted to iodide by the addition of a strong solution of sodium sulphite. The iodide was then precipitated as palladium iodide using a solution of palladium chloride. The precipitate was filtered through membrane filter paper, air-dried and analyzed using the Energy Dispersive X-Ray Fluorescence (EDXRF) method.","Sample preparation technique for iodine determination in urine and water samples Abs: A simple method for iodine determination in urine and water samples is presented. After digestion of the sample with chromic acid, the iodate produced was converted to iodide by the addition of a strong solution of sodium sulphite. The iodide was then precipitated as palladium iodide using a solution of palladium chloride. The precipitate was filtered through membrane filter paper, air-dried and analyzed using the Energy Dispersive X-Ray Fluorescence (EDXRF) method."
1230955,Hayashi et al. 1994,"Nisamycin, a new manumycin group antibiotic from Streptomyces sp. K106. II. Structure determination and structure-activity relationships","Nisamycin, a novel manumycin group antibiotic, was isolated from the culture broth of Streptomyces sp. K106. Structural elucidation of nisamycin was achieved by detailed NMR spectral analyses and comparison of the NMR data of nisamycin with those of other manumycin group antibiotics. The structure was confirmed by chromic acid oxidation. The absolute stereochemistry of nisamycin was determined to be 4R, 5S and 6R from the CD spectra of nisamycin and chromic oxidation of nisamycin. In addition, some structure activity-relationships were examined.","Nisamycin, a new manumycin group antibiotic from Streptomyces sp. K106. II. Structure determination and structure-activity relationships Abs: Nisamycin, a novel manumycin group antibiotic, was isolated from the culture broth of Streptomyces sp. K106. Structural elucidation of nisamycin was achieved by detailed NMR spectral analyses and comparison of the NMR data of nisamycin with those of other manumycin group antibiotics. The structure was confirmed by chromic acid oxidation. The absolute stereochemistry of nisamycin was determined to be 4R, 5S and 6R from the CD spectra of nisamycin and chromic oxidation of nisamycin. In addition, some structure activity-relationships were examined."
1230954,Gandolfi et al. 1995,"Chromophore-modified antitumor anthracenediones: synthesis, DNA binding, and cytotoxic activity of 1,4-bis[(aminoalkyl)amino]benzo[g]-phthalazine-5,10-diones","As part of a program aimed at exploring the effect of the introduction of heteroatoms into the anthracene-9,10-dione chromophore, we have synthesized novel 1,4-bis[(aminoalkyl)amino]-benzo[g]phthalazine-5,10-diones (BPDs) 1 which are related to the antitumor agents ametantrone and mitoxantrone. Derivatives 1 were prepared by chromic acid oxidation of acylated benzo[g]phthalazines 5 followed by acid hydrolysis or by silylation-amination of 5,10-dihydroxybenzo[g]phthalazine-1,4-dione (8). The 1-[(aminoalkyl)amino]-4-amino congeners 2 were isolated in low yields as byproducts from the oxidation of 5. Against a panel of human tumor cell lines, the benzo[g]phthalazine-5,10-diones 1 and 2 exhibited cytotoxic activity comparable or even superior to that of mitoxantrone. In compounds 1, structure-activity relationships different than those operative in the carbocyclic series appeared to emerge. DNA-binding studies with the ametantrone-like compound 1c and its single-armed congener 2c indicated that the introduction of a 2,3-diaza subunit into the anthracene-9,10-dione chromophore reduces the affinity of the drug for DNA in comparison with ametantrone. On the other hand, the number of side-chain groups does not affect binding to a great extent. These findings seem to suggest mechanisms of cell death other than those induced by simple interaction of the 1,4-BPDs 1 and 2 with DNA.","Chromophore-modified antitumor anthracenediones: synthesis, DNA binding, and cytotoxic activity of 1,4-bis[(aminoalkyl)amino]benzo[g]-phthalazine-5,10-diones Abs: As part of a program aimed at exploring the effect of the introduction of heteroatoms into the anthracene-9,10-dione chromophore, we have synthesized novel 1,4-bis[(aminoalkyl)amino]-benzo[g]phthalazine-5,10-diones (BPDs) 1 which are related to the antitumor agents ametantrone and mitoxantrone. Derivatives 1 were prepared by chromic acid oxidation of acylated benzo[g]phthalazines 5 followed by acid hydrolysis or by silylation-amination of 5,10-dihydroxybenzo[g]phthalazine-1,4-dione (8). The 1-[(aminoalkyl)amino]-4-amino congeners 2 were isolated in low yields as byproducts from the oxidation of 5. Against a panel of human tumor cell lines, the benzo[g]phthalazine-5,10-diones 1 and 2 exhibited cytotoxic activity comparable or even superior to that of mitoxantrone. In compounds 1, structure-activity relationships different than those operative in the carbocyclic series appeared to emerge. DNA-binding studies with the ametantrone-like compound 1c and its single-armed congener 2c indicated that the introduction of a 2,3-diaza subunit into the anthracene-9,10-dione chromophore reduces the affinity of the drug for DNA in comparison with ametantrone. On the other hand, the number of side-chain groups does not affect binding to a great extent. These findings seem to suggest mechanisms of cell death other than those induced by simple interaction of the 1,4-BPDs 1 and 2 with DNA."
1230953,Alexander and  Aaseth 1995,Uptake of chromate in human red blood cells and isolated rat liver cells: the role of the anion carrier,"The transport of [51Cr]chromate into human erythrocytes and isolated rat hepatocytes has been investigated. It was found that uptake in both cell types could be inhibited by the established anion carrier inhibitor 4,4'-diisothiocyanatostilbene-2,2'-disulfonic acid. The uptake was very fast, and in kinetic studies a very low Km was found for both cell types, indicating either a high affinity of chromate for the carrier, and/or, more probably, an efficient intracellular reduction and trapping of 51Cr. The transport capacity, however, was of the same magnitude as for physiological substrates, such as lactate and sulfate. The uptake was temperature dependent and the activation energy was of the same magnitude as that for the physiological substrates. The uptake could be partly inhibited by high levels (mmol l-1) of lactate, pyruvate or sulfate. The uptake rate was greatly increased at lower pH (6.0 versus 7.4) which could indicate transport of the HCrO4- form or an increased intracellular rate of CrVI reduction. The results showed efficient uptake of 51CrO4(2-) by erythrocytes and hepatocytes. They were consistent with a mechanism of uptake which involved the cell membrane anion-exchange carrier in the transport and trapping of 51Cr within the cell.","Uptake of chromate in human red blood cells and isolated rat liver cells: the role of the anion carrier Abs: The transport of [51Cr]chromate into human erythrocytes and isolated rat hepatocytes has been investigated. It was found that uptake in both cell types could be inhibited by the established anion carrier inhibitor 4,4'-diisothiocyanatostilbene-2,2'-disulfonic acid. The uptake was very fast, and in kinetic studies a very low Km was found for both cell types, indicating either a high affinity of chromate for the carrier, and/or, more probably, an efficient intracellular reduction and trapping of 51Cr. The transport capacity, however, was of the same magnitude as for physiological substrates, such as lactate and sulfate. The uptake was temperature dependent and the activation energy was of the same magnitude as that for the physiological substrates. The uptake could be partly inhibited by high levels (mmol l-1) of lactate, pyruvate or sulfate. The uptake rate was greatly increased at lower pH (6.0 versus 7.4) which could indicate transport of the HCrO4- form or an increased intracellular rate of CrVI reduction. The results showed efficient uptake of 51CrO4(2-) by erythrocytes and hepatocytes. They were consistent with a mechanism of uptake which involved the cell membrane anion-exchange carrier in the transport and trapping of 51Cr within the cell."
1230951,Funayama et al. 1995,Recurrent meningitis in a case of congenital anterior sacral meningocele and agenesis of sacral and coccygeal vertebrae,"A rare case of recurrent meningitis due to congenital anterior sacral meningocele and agenesis of the sacral and coccygeal vertebrae is described. An autosomal dominant inheritance is demonstrated for lower cord malformation, and environmental factors (chromic acid or fumes) are discussed.","Recurrent meningitis in a case of congenital anterior sacral meningocele and agenesis of sacral and coccygeal vertebrae Abs: A rare case of recurrent meningitis due to congenital anterior sacral meningocele and agenesis of the sacral and coccygeal vertebrae is described. An autosomal dominant inheritance is demonstrated for lower cord malformation, and environmental factors (chromic acid or fumes) are discussed."
1230950,Hailey et al. 1996,Ultra-high molecular weight polyethylene wear debris generated in vivo and in laboratory tests; the influence of counterface roughness,"The objective of this study was to investigate the effect of counterface roughness and lubricant on the morphology of ultra-high molecular weight polyethylene (UHMWPE) wear debris generated in laboratory wear tests, and to compare this with debris isolated from explanted tissue. Laboratory tests used UHMWPE pins sliding against stainless steel counterfaces. Both water and serum lubricants were used in conjunction with rough and smooth counterfaces. The lubricants and tissue from revision hip surgery were processed to digest the proteins and permit filtration. This involved denaturing the proteins with potassium hydroxide (KOH), sedimentation of any remaining proteins, and further digestion of these proteins with chromic acid. All fractions were then passed through a 0.2 micron membrane, and the debris examined using scanning electron microscopy. The laboratory studies showed that the major variable influencing debris morphology was counterface roughness. The rougher counterfaces produced larger numbers of smaller particles, with a size range extending below 1 micron. For smooth counterfaces there were fewer of these small particles, and evidence of larger platelets, greater than 10 microns in diameter. Analysis of the debris from explanted tissues showed a wide variation in the particle size distribution, ranging from below 1 micron up to several millimetres in size. Of major clinical significance in relation to osteolysis and loosening is roughening of the femoral components, which may lead to greater numbers of the sub-micron-sized particles.","Ultra-high molecular weight polyethylene wear debris generated in vivo and in laboratory tests; the influence of counterface roughness Abs: The objective of this study was to investigate the effect of counterface roughness and lubricant on the morphology of ultra-high molecular weight polyethylene (UHMWPE) wear debris generated in laboratory wear tests, and to compare this with debris isolated from explanted tissue. Laboratory tests used UHMWPE pins sliding against stainless steel counterfaces. Both water and serum lubricants were used in conjunction with rough and smooth counterfaces. The lubricants and tissue from revision hip surgery were processed to digest the proteins and permit filtration. This involved denaturing the proteins with potassium hydroxide (KOH), sedimentation of any remaining proteins, and further digestion of these proteins with chromic acid. All fractions were then passed through a 0.2 micron membrane, and the debris examined using scanning electron microscopy. The laboratory studies showed that the major variable influencing debris morphology was counterface roughness. The rougher counterfaces produced larger numbers of smaller particles, with a size range extending below 1 micron. For smooth counterfaces there were fewer of these small particles, and evidence of larger platelets, greater than 10 microns in diameter. Analysis of the debris from explanted tissues showed a wide variation in the particle size distribution, ranging from below 1 micron up to several millimetres in size. Of major clinical significance in relation to osteolysis and loosening is roughening of the femoral components, which may lead to greater numbers of the sub-micron-sized particles."
1230949,Goldberg and  Septier 1996,"A comparative study of the transition between predentin and dentin, using various preparative procedures in the rat","The appearance of the junction between predentin and dentin of rat incisors was investigated after chemical fixation (aldehyde), physical fixation (high pressure freezing and freeze substitution) and by histochemistry. Physical fixation revealed a 1-2 micron wide intermediary zone, in which only the collagen fibers were mineralized. In dentin, which looked denser and more homogeneous, both collagen fibers and intercollagenous spaces were mineralized. The intermediary layer could not been seen after aldehyde fixation. When cationic dyes were used during fixation in order to retain proteoglycans, a 0.5-5 micron border zone located at the junction between predentin and dentin was densely stained on the dentin side, whereas in dentin only the interglobular network displayed electron density. The periodic acid-thiocarbohydrazide-silver proteinate reaction, visualizing glycoproteins, and the phosphotungstic acid/chromic acid mixture, which reveals glycoproteins and phosphorylated proteins, produced extensive staining of the transitional zone located at the dentin edge, whereas staining was weaker in dentin. These morphological and histochemical investigations support the existence of an intermediary zone in which mineralization occurs. This transitional zone between predentin and dentin has specific properties; therefore we propose it be termed metadentin.","A comparative study of the transition between predentin and dentin, using various preparative procedures in the rat Abs: The appearance of the junction between predentin and dentin of rat incisors was investigated after chemical fixation (aldehyde), physical fixation (high pressure freezing and freeze substitution) and by histochemistry. Physical fixation revealed a 1-2 micron wide intermediary zone, in which only the collagen fibers were mineralized. In dentin, which looked denser and more homogeneous, both collagen fibers and intercollagenous spaces were mineralized. The intermediary layer could not been seen after aldehyde fixation. When cationic dyes were used during fixation in order to retain proteoglycans, a 0.5-5 micron border zone located at the junction between predentin and dentin was densely stained on the dentin side, whereas in dentin only the interglobular network displayed electron density. The periodic acid-thiocarbohydrazide-silver proteinate reaction, visualizing glycoproteins, and the phosphotungstic acid/chromic acid mixture, which reveals glycoproteins and phosphorylated proteins, produced extensive staining of the transitional zone located at the dentin edge, whereas staining was weaker in dentin. These morphological and histochemical investigations support the existence of an intermediary zone in which mineralization occurs. This transitional zone between predentin and dentin has specific properties; therefore we propose it be termed metadentin."
1230947,Kuo et al. 1997,Nasal septum lesions and lung function in workers exposed to chromic acid in electroplating factories,"The objective of this study was to compare workers from chromium, nickel-chromium, and zinc electroplating factories with regards to nasal septum lesions and lung function. Also investigated was the relationship between chromium levels in air and urine. A total of 189 workers from 11 electroplating factories (three chromium, six nickel-chromium, two zinc) were chosen from central Taiwan. All subjects were interviewed by constructed-questionnaire, given a nasal examination by a certified otolaryngologist and a lung function test. In the chromium factories 30.8% of the workers showed evidence of nasal septum perforations and 38.5% showed evidence of nasal septum ulcers. A Mantel extension test for trend showed that workers in the chromium factories were 31.7 times more likely to experience nasal ulcers than nickel-chromium and zinc factory workers. Those who worked in the electroplating tank area were 4.2 times more likely to experience ulcers and those with over 9 years' experience were 30.8 times more likely. A comparison of lung function adjusted for age, gender and smoking habit among workers showed that vital capacity (VC), forced vital capacity (FVC), and forced expiratory volume in 1 s (FEV1) were all significantly decreased among chromium factory workers. Because the results showed that the workers' health is being severely damaged by the harmful environment of chromium electroplating factories, the authors wish to suggest improvements in the workplace are vitally needed to ensure the safety of the workers.","Nasal septum lesions and lung function in workers exposed to chromic acid in electroplating factories Abs: The objective of this study was to compare workers from chromium, nickel-chromium, and zinc electroplating factories with regards to nasal septum lesions and lung function. Also investigated was the relationship between chromium levels in air and urine. A total of 189 workers from 11 electroplating factories (three chromium, six nickel-chromium, two zinc) were chosen from central Taiwan. All subjects were interviewed by constructed-questionnaire, given a nasal examination by a certified otolaryngologist and a lung function test. In the chromium factories 30.8% of the workers showed evidence of nasal septum perforations and 38.5% showed evidence of nasal septum ulcers. A Mantel extension test for trend showed that workers in the chromium factories were 31.7 times more likely to experience nasal ulcers than nickel-chromium and zinc factory workers. Those who worked in the electroplating tank area were 4.2 times more likely to experience ulcers and those with over 9 years' experience were 30.8 times more likely. A comparison of lung function adjusted for age, gender and smoking habit among workers showed that vital capacity (VC), forced vital capacity (FVC), and forced expiratory volume in 1 s (FEV1) were all significantly decreased among chromium factory workers. Because the results showed that the workers' health is being severely damaged by the harmful environment of chromium electroplating factories, the authors wish to suggest improvements in the workplace are vitally needed to ensure the safety of the workers."
1230946,Rathkolb et al. 1997,Identification of leucocyte surface antigens in paraffin-embedded bovine tissues using a modified formalin dichromate fixation,"A modified fixative of formalin dichromate was combined with a cold embedding procedure for the preservation of bovine leucocyte surface antigens. Fourteen monoclonal antibodies recognizing seven bovine leucocyte surface antigens (BoCD1w2, BoCD4, BoCD8, BoWC1, BoWC3, BoWC4 and BoIgM) were applied as primary antisera in a sensitive avidin-biotin-peroxidase complex detection method. The staining results were compared with those obtained in cryostat and routinely formalin-fixed sections of corresponding tissue samples. Using the modified formalin dichromate fixative and the cold embedding procedure, all the leucocyte surface antigens tested were detectable immunohistologically in paraffin sections with a generally more distinct staining than in traditionally processed tissues. Morphological structures were better preserved than in cryostat sections but, to some extent, were poorer when compared with routinely formalinfixed tissues. However, this method suggests that there are only mild masking effects and provides an alternative to the use of unfixed material, particularly for morphological-immunohistochemical investigations.","Identification of leucocyte surface antigens in paraffin-embedded bovine tissues using a modified formalin dichromate fixation Abs: A modified fixative of formalin dichromate was combined with a cold embedding procedure for the preservation of bovine leucocyte surface antigens. Fourteen monoclonal antibodies recognizing seven bovine leucocyte surface antigens (BoCD1w2, BoCD4, BoCD8, BoWC1, BoWC3, BoWC4 and BoIgM) were applied as primary antisera in a sensitive avidin-biotin-peroxidase complex detection method. The staining results were compared with those obtained in cryostat and routinely formalin-fixed sections of corresponding tissue samples. Using the modified formalin dichromate fixative and the cold embedding procedure, all the leucocyte surface antigens tested were detectable immunohistologically in paraffin sections with a generally more distinct staining than in traditionally processed tissues. Morphological structures were better preserved than in cryostat sections but, to some extent, were poorer when compared with routinely formalinfixed tissues. However, this method suggests that there are only mild masking effects and provides an alternative to the use of unfixed material, particularly for morphological-immunohistochemical investigations."
1230945,Sorahan et al. 1998,"Lung cancer mortality in nickel/chromium platers, 1946-95","OBJECTIVES: To investigate mortality from lung cancer in nickel/chromium platers. METHODS: The mortality experience of a cohort of 1762 chrome workers (812 men, 950 women) from a large electroplating and light engineering plant in the Midlands, United Kingdom, was investigated for the period 1946-95. All subjects were first employed in chrome work at the plant during the period 1946-75, and had at least six months employment in jobs associated with exposure to chromic acid mist (hexavalent chromium). Detailed job histories were abstracted from original company personnel records and individual cumulative durations of employment in three types of chrome work were derived as time dependent variables (chrome bath work, other chrome work, any chrome work). Two analytical approaches were used--indirect standardisation and Poisson regression. RESULTS: Based on mortalities for the general population of England and Wales, male workers with some period of chrome bath work had higher lung cancer mortalities (observed deaths 40, expected deaths 25.41, standardised mortality ratio (SMR) 157, 95% confidence interval (95% CI) 113 to 214, p < 0.01) than did other male chrome workers (observed 9, expected 13.70, SMR 66, 95% CI 30 to 125). Similar findings were shown for female workers (chrome bath workers: observed 15, expected 8.57, SMR 175, 95% CI 98 to 289, p = 0.06; other chrome workers: observed 1, expected 4.37, SMR 23, 95% CI 1 to 127). Poisson regression was used to investigate risks of lung cancer relative to four categories of cumulative duration of chrome bath work and four categories of cumulative duration of other chrome work (none, < 1 y, 1-4 y, > or = 5 y). After adjusting for sex, age, calendar period, year of starting chrome work, period from first chrome work, and employment status (still employed v left employment), there was a significant positive trend (p < 0.05) between duration of chrome bath work and risks of mortality for lung cancer. Relative to a risk of unity for those chrome workers without any period of chrome bath work, risks were 2.83 (95% CI 1.47 to 5.45), 1.61 (95% CI 0.75 to 3.44), and 4.25 (95% CI 1.83 to 9.87) for the second, third, and fourth exposure categories, respectively. Duration of other chrome work was not a useful predictor of risks of lung cancer. Similar findings for both variables were obtained when adjustment was made for sex and age only. Similar findings for both variables were obtained relative to risk of chrome nasal ulceration. CONCLUSIONS: The findings are consistent with the hypothesis that soluble hexavalent chromium compounds are potent human lung carcinogens.","Lung cancer mortality in nickel/chromium platers, 1946-95 Abs: OBJECTIVES: To investigate mortality from lung cancer in nickel/chromium platers. METHODS: The mortality experience of a cohort of 1762 chrome workers (812 men, 950 women) from a large electroplating and light engineering plant in the Midlands, United Kingdom, was investigated for the period 1946-95. All subjects were first employed in chrome work at the plant during the period 1946-75, and had at least six months employment in jobs associated with exposure to chromic acid mist (hexavalent chromium). Detailed job histories were abstracted from original company personnel records and individual cumulative durations of employment in three types of chrome work were derived as time dependent variables (chrome bath work, other chrome work, any chrome work). Two analytical approaches were used--indirect standardisation and Poisson regression. RESULTS: Based on mortalities for the general population of England and Wales, male workers with some period of chrome bath work had higher lung cancer mortalities (observed deaths 40, expected deaths 25.41, standardised mortality ratio (SMR) 157, 95% confidence interval (95% CI) 113 to 214, p < 0.01) than did other male chrome workers (observed 9, expected 13.70, SMR 66, 95% CI 30 to 125). Similar findings were shown for female workers (chrome bath workers: observed 15, expected 8.57, SMR 175, 95% CI 98 to 289, p = 0.06; other chrome workers: observed 1, expected 4.37, SMR 23, 95% CI 1 to 127). Poisson regression was used to investigate risks of lung cancer relative to four categories of cumulative duration of chrome bath work and four categories of cumulative duration of other chrome work (none, < 1 y, 1-4 y, > or = 5 y). After adjusting for sex, age, calendar period, year of starting chrome work, period from first chrome work, and employment status (still employed v left employment), there was a significant positive trend (p < 0.05) between duration of chrome bath work and risks of mortality for lung cancer. Relative to a risk of unity for those chrome workers without any period of chrome bath work, risks were 2.83 (95% CI 1.47 to 5.45), 1.61 (95% CI 0.75 to 3.44), and 4.25 (95% CI 1.83 to 9.87) for the second, third, and fourth exposure categories, respectively. Duration of other chrome work was not a useful predictor of risks of lung cancer. Similar findings for both variables were obtained when adjustment was made for sex and age only. Similar findings for both variables were obtained relative to risk of chrome nasal ulceration. CONCLUSIONS: The findings are consistent with the hypothesis that soluble hexavalent chromium compounds are potent human lung carcinogens."
1230943,Fernandes et al. 1999,Human erythrocytes are protected against chromate-induced peroxidation,"In previous studies performed in this laboratory it was realized that in a broad concentration range (0.5-8 mM) dichromate does not induced red blood cell (RBC) peroxidation. To investigate the reasons behind RBC protection against chromate-induced peroxidation, the effects of 8 mM dichromate on white ghost and RBC peroxidation, RBC antioxidant system and hemoglobin status, as well as RBC osmotic fragility and morphology, were studied in more detail. It was observed that the peroxidation level induced by dichromate on RBCs is practically negligible when compared with the peroxidation induced in white ghosts. Furthermore, the osmotic fragility of RBCs exposed to dichromate is not altered, but the cells undergo echinocytic transformation, probably due to chromate-induced structural RBC membrane modifications. The activities of catalase, gluthatione peroxidase, and superoxide dismutase of RBCs exposed to dichromate were similar to those observed in controls, but the gluthatione reductase and GSH levels were significantly reduced (P&lt;0. 05). Concomitantly, GSSG and methemoglobin levels increased and NADH-methemoglobin reductase activity decreased. These results indicate that chromate does not induce RBC peroxidation, but does promote echinocytic shape transformation, oxidation of hemoglobin and GSH, and inhibition of gluthatione reductase and methemoglobin reductase. The enzymatic antioxidant defense system and hemoglobin oxidation are probably involved in the mechanism of RBC proctection against chromate-induced peroxidation, as is discussed.","Human erythrocytes are protected against chromate-induced peroxidation Abs: In previous studies performed in this laboratory it was realized that in a broad concentration range (0.5-8 mM) dichromate does not induced red blood cell (RBC) peroxidation. To investigate the reasons behind RBC protection against chromate-induced peroxidation, the effects of 8 mM dichromate on white ghost and RBC peroxidation, RBC antioxidant system and hemoglobin status, as well as RBC osmotic fragility and morphology, were studied in more detail. It was observed that the peroxidation level induced by dichromate on RBCs is practically negligible when compared with the peroxidation induced in white ghosts. Furthermore, the osmotic fragility of RBCs exposed to dichromate is not altered, but the cells undergo echinocytic transformation, probably due to chromate-induced structural RBC membrane modifications. The activities of catalase, gluthatione peroxidase, and superoxide dismutase of RBCs exposed to dichromate were similar to those observed in controls, but the gluthatione reductase and GSH levels were significantly reduced (P&lt;0. 05). Concomitantly, GSSG and methemoglobin levels increased and NADH-methemoglobin reductase activity decreased. These results indicate that chromate does not induce RBC peroxidation, but does promote echinocytic shape transformation, oxidation of hemoglobin and GSH, and inhibition of gluthatione reductase and methemoglobin reductase. The enzymatic antioxidant defense system and hemoglobin oxidation are probably involved in the mechanism of RBC proctection against chromate-induced peroxidation, as is discussed."
1230940,Antel 1999,Multiple sclerosis--emerging concepts of disease pathogenesis,"Multiple sclerosis has been recognized as a clinical pathologic entity for more than a century. The pioneering microscopic anatomic studies of Charcot illustrate the power of careful observations taking maximal advantage of available technology. Using carmine as 'a precious agent' to stain spinal cord hardened with dilute chromic acid, he described the characteristic myelin loss with relative but not absolute axonal preservation. This presentation summarizes how following the principle of careful application of emerging technologies to MS patients and their tissues, as described in this symposium, as the foundation for our continuing advances regarding the etiology and pathogenesis of MS.","Multiple sclerosis--emerging concepts of disease pathogenesis Abs: Multiple sclerosis has been recognized as a clinical pathologic entity for more than a century. The pioneering microscopic anatomic studies of Charcot illustrate the power of careful observations taking maximal advantage of available technology. Using carmine as 'a precious agent' to stain spinal cord hardened with dilute chromic acid, he described the characteristic myelin loss with relative but not absolute axonal preservation. This presentation summarizes how following the principle of careful application of emerging technologies to MS patients and their tissues, as described in this symposium, as the foundation for our continuing advances regarding the etiology and pathogenesis of MS."
1230939,Falch et al. 1999,"Selective inhibitors of glial GABA uptake: synthesis, absolute stereochemistry, and pharmacology of the enantiomers of 3-hydroxy-4-amino-4,5,6,7-tetrahydro-1,2-benzisoxazole (exo-THPO) and analogues","3-Methoxy-4,5,6,7-tetrahydro-1,2-benzisoxazol-4-one (20a), or the corresponding 3-ethoxy analogue (20b), and 3-chloro-4,5,6, 7-tetrahydro-1,2-benzisothiazol-4-one (51) were synthesized by regioselective chromic acid oxidation of the respective bicyclic tetrahydrobenzenes 19a,b and 50, and they were used as key intermediates for the syntheses of the target zwitterionic 3-isoxazolols 8-15 and 3-isothiazolols 16 and 17, respectively. These reaction sequences involved different reductive processes. Whereas (RS)-4-amino-3-hydroxy-4,5,6,7-tetrahydro-1,2-benzisoxazole (8, exo-THPO) was synthesized via aluminum amalgam reduction of oxime 22a or 22b, compounds 9, 11-13, and 15-17 were obtained via reductive aminations. Compound 10 was synthesized via N-ethylation of the N-Boc-protected primary amine 25. The enantiomers of 8 were obtained in high enantiomeric purities (ee &gt;/= 99.1%) via the diastereomeric amides 32 and 33, synthesized from the primary amine 23b and (R)-alpha-methoxyphenylacetyl chloride and subsequent separation by preparative HPLC. The enantiomers of 9 were prepared analogously from the secondary amine 27. On the basis of X-ray crystallographic analyses, the configuration of oxime 22a was shown to be E and the absolute configurations of (-)-8 x HCl and (+)-9 x HBr were established to be R. The effects of the target compounds on GABA uptake mechanisms in vitro were measured using a rat brain synaptosomal preparation and primary cultures of mouse cortical neurons and glia cells (astrocytes). Whereas the classical GABA uptake inhibitor, (R)-nipecotic acid (2), nonselectively inhibits neuronal (IC(50) = 12 microM) and glial (IC(50) = 16 microM) GABA uptake and 4,5,6,7-tetrahydroisoxazolo¿4,5-cpyridin-3-ol (1, THPO) shows some selectivity for glial (IC(50) = 268 microM) versus neuronal (IC(50) = 530 microM) GABA uptake, exo-THPO (8) was shown to be more potent as an inhibitor of glial (IC(50) = 200 microM) rather than neuronal (IC(50) = 900 microM) GABA uptake. This selectivity was more pronounced for 9, which showed IC(50) values of 40 and 500 microM as an inhibitor of glial and neuronal GABA uptake, respectively. These effects of 8 and 9 proved to be enantioselective, (R)-(-)-8 and (R)-(+)-9 being the active inhibitors of both uptake systems. The selectivity of 9 as a glial GABA uptake inhibitor was largely lost by replacing the N-methyl group of 9 by an ethyl group, compound 10 being an almost equipotent inhibitor of glial (IC(50) = 280 microM) and neuronal (IC(50) = 400 microM) GABA uptake. The remaining target compounds, 11-17, were very weak or inactive as inhibitors of both uptake systems. Compounds 9-13 and 15 were shown to be essentially inactive against isoniazide-induced convulsions in mice after subcutaneous administration. The isomeric pivaloyloxymethyl derivatives of 9, compounds 43 and 44, were synthesized and tested as potential prodrugs in the isoniazide animal model. Both 43 (ED(50) = 150 micromol/kg) and 44 (ED(50) = 220 micromol/kg) showed anticonvulsant effects, and this effect of 43 was shown to reside in the (R)-(+)-enantiomer, 45 (ED(50) = 44 micromol/kg). Compound 9 also showed anticonvulsant activity when administered intracerebroventricularly (ED(50) = 59 nmol).","Selective inhibitors of glial GABA uptake: synthesis, absolute stereochemistry, and pharmacology of the enantiomers of 3-hydroxy-4-amino-4,5,6,7-tetrahydro-1,2-benzisoxazole (exo-THPO) and analogues Abs: 3-Methoxy-4,5,6,7-tetrahydro-1,2-benzisoxazol-4-one (20a), or the corresponding 3-ethoxy analogue (20b), and 3-chloro-4,5,6, 7-tetrahydro-1,2-benzisothiazol-4-one (51) were synthesized by regioselective chromic acid oxidation of the respective bicyclic tetrahydrobenzenes 19a,b and 50, and they were used as key intermediates for the syntheses of the target zwitterionic 3-isoxazolols 8-15 and 3-isothiazolols 16 and 17, respectively. These reaction sequences involved different reductive processes. Whereas (RS)-4-amino-3-hydroxy-4,5,6,7-tetrahydro-1,2-benzisoxazole (8, exo-THPO) was synthesized via aluminum amalgam reduction of oxime 22a or 22b, compounds 9, 11-13, and 15-17 were obtained via reductive aminations. Compound 10 was synthesized via N-ethylation of the N-Boc-protected primary amine 25. The enantiomers of 8 were obtained in high enantiomeric purities (ee &gt;/= 99.1%) via the diastereomeric amides 32 and 33, synthesized from the primary amine 23b and (R)-alpha-methoxyphenylacetyl chloride and subsequent separation by preparative HPLC. The enantiomers of 9 were prepared analogously from the secondary amine 27. On the basis of X-ray crystallographic analyses, the configuration of oxime 22a was shown to be E and the absolute configurations of (-)-8 x HCl and (+)-9 x HBr were established to be R. The effects of the target compounds on GABA uptake mechanisms in vitro were measured using a rat brain synaptosomal preparation and primary cultures of mouse cortical neurons and glia cells (astrocytes). Whereas the classical GABA uptake inhibitor, (R)-nipecotic acid (2), nonselectively inhibits neuronal (IC(50) = 12 microM) and glial (IC(50) = 16 microM) GABA uptake and 4,5,6,7-tetrahydroisoxazolo¿4,5-cpyridin-3-ol (1, THPO) shows some selectivity for glial (IC(50) = 268 microM) versus neuronal (IC(50) = 530 microM) GABA uptake, exo-THPO (8) was shown to be more potent as an inhibitor of glial (IC(50) = 200 microM) rather than neuronal (IC(50) = 900 microM) GABA uptake. This selectivity was more pronounced for 9, which showed IC(50) values of 40 and 500 microM as an inhibitor of glial and neuronal GABA uptake, respectively. These effects of 8 and 9 proved to be enantioselective, (R)-(-)-8 and (R)-(+)-9 being the active inhibitors of both uptake systems. The selectivity of 9 as a glial GABA uptake inhibitor was largely lost by replacing the N-methyl group of 9 by an ethyl group, compound 10 being an almost equipotent inhibitor of glial (IC(50) = 280 microM) and neuronal (IC(50) = 400 microM) GABA uptake. The remaining target compounds, 11-17, were very weak or inactive as inhibitors of both uptake systems. Compounds 9-13 and 15 were shown to be essentially inactive against isoniazide-induced convulsions in mice after subcutaneous administration. The isomeric pivaloyloxymethyl derivatives of 9, compounds 43 and 44, were synthesized and tested as potential prodrugs in the isoniazide animal model. Both 43 (ED(50) = 150 micromol/kg) and 44 (ED(50) = 220 micromol/kg) showed anticonvulsant effects, and this effect of 43 was shown to reside in the (R)-(+)-enantiomer, 45 (ED(50) = 44 micromol/kg). Compound 9 also showed anticonvulsant activity when administered intracerebroventricularly (ED(50) = 59 nmol)."
1230938,Sorahan and  Harrington 2000,"Lung cancer in Yorkshire chrome platers, 1972-97","<strong>OBJECTIVES: </strong>To investigate mortality from lung cancer in chrome platers, a group exposed to chromic acid.<br /><br /><strong>METHODS: </strong>The mortality of a cohort of 1087 chrome platers (920 men, 167 women) from 54 plants situated in the West Riding of Yorkshire, United Kingdom, was investigated for the period 1972-97. All subjects were employed as chrome platers for &gt;/=3 months and all were alive on 31 May 1972. Mortality data were also available for a cohort of 1163 comparison workers with no known occupational exposure to chrome compounds (989 men, 174 women). Information on duration of chrome work and smoking habits collected for a cross sectional survey carried out in 1969-72 were available for 916 (84.3%) of the chrome platers; smoking habits were available for 1004 (86.3%) comparison workers. Two analytical approaches were used, indirect standardisation and Poisson regression.<br /><br /><strong>RESULTS: </strong>Based on serial mortality rates for the general population of England and Wales, significantly increased mortality from lung cancer was observed (obs) in male chrome platers (obs 60, expected (exp) 32.5, standardised mortality ratio (SMR) 185, p&lt;0. 001) but not in male comparison workers (obs 47, exp 36.9, SMR 127). Positive trends were not shown for duration of employment exposed to chrome, although data on working after 1972 were not available.<br /><br /><strong>CONCLUSIONS: </strong>Confident interpretation is not possible but occupational exposures to hexavalent chromium may well have been involved in the increased mortality from lung cancer found in this cohort of chrome platers.","Lung cancer in Yorkshire chrome platers, 1972-97 Abs: <strong>OBJECTIVES: </strong>To investigate mortality from lung cancer in chrome platers, a group exposed to chromic acid.<br /><br /><strong>METHODS: </strong>The mortality of a cohort of 1087 chrome platers (920 men, 167 women) from 54 plants situated in the West Riding of Yorkshire, United Kingdom, was investigated for the period 1972-97. All subjects were employed as chrome platers for &gt;/=3 months and all were alive on 31 May 1972. Mortality data were also available for a cohort of 1163 comparison workers with no known occupational exposure to chrome compounds (989 men, 174 women). Information on duration of chrome work and smoking habits collected for a cross sectional survey carried out in 1969-72 were available for 916 (84.3%) of the chrome platers; smoking habits were available for 1004 (86.3%) comparison workers. Two analytical approaches were used, indirect standardisation and Poisson regression.<br /><br /><strong>RESULTS: </strong>Based on serial mortality rates for the general population of England and Wales, significantly increased mortality from lung cancer was observed (obs) in male chrome platers (obs 60, expected (exp) 32.5, standardised mortality ratio (SMR) 185, p&lt;0. 001) but not in male comparison workers (obs 47, exp 36.9, SMR 127). Positive trends were not shown for duration of employment exposed to chrome, although data on working after 1972 were not available.<br /><br /><strong>CONCLUSIONS: </strong>Confident interpretation is not possible but occupational exposures to hexavalent chromium may well have been involved in the increased mortality from lung cancer found in this cohort of chrome platers."
1230937,Benczek et al. 2000,Prediction of toxic substances emission for occupational exposure assessment,"Methods for predicting organic solvents, chromic acid, mineral oil, styrene, and sulphuric acid emissions in painting, metal degreasing, wood preservation, chromium electroplating, turning, grinding, making glass fortified polyester laminates and lead batteries charging, injection moulding of polystyrene plastics, and making polyurethane foam processes are described. Experimentally introduced equations are based on the essential parameters of these processes. Knowing the emission and the total flow rate of ventilation, it is possible to calculate toxic agent concentration, which is the basis of occupational exposure assessment.","Prediction of toxic substances emission for occupational exposure assessment Abs: Methods for predicting organic solvents, chromic acid, mineral oil, styrene, and sulphuric acid emissions in painting, metal degreasing, wood preservation, chromium electroplating, turning, grinding, making glass fortified polyester laminates and lead batteries charging, injection moulding of polystyrene plastics, and making polyurethane foam processes are described. Experimentally introduced equations are based on the essential parameters of these processes. Knowing the emission and the total flow rate of ventilation, it is possible to calculate toxic agent concentration, which is the basis of occupational exposure assessment."
1230936,Shin and  Paik 2000,Reduction of hexavalent chromium collected on PVC filters,"Chromium exists at various valences, including elemental, trivalent, and hexavalent chromium, and undergoes reduction-oxidation reactions in the environment. Since hexavalent chromium is known as a human carcinogen, it is most important to evaluate the oxidation-reduction characteristics of the hexavalent chromium species. Although hexavalent chromium can be reduced to trivalent state, the detailed information on this in workplace environments is limited. The purpose of this study was to investigate hexavalent chromium reduction in time in various conditions. A pilot chrome plating operation was prepared and operated in a laboratory for this study. There was evidence that the hexavalent chromium was reduced by time after mist generation. The percentage ratio (with 95% confidence intervals in parentheses) of hexavalent chromium to total chromium was almost 100% (99.1 approximately 102.3) immediately after mist generation, and was reduced to 87.4% (84.8 approximately 89.9) at 1 hour and 81.0% (78.3 approximately 83.5) at 2 hours, respectively. Another test indicated that hexavalent chromium collected on PVC filters was also reduced by time after sampling. Hexavalent chromium was reduced to 90.8% (88.2 approximately 93.3) at 2 hours after sampling. It also was found that hexavalent chromium was reduced during storage in air. It is recommended that air samples of hexavalent chromium be protected against reduction during storage.","Reduction of hexavalent chromium collected on PVC filters Abs: Chromium exists at various valences, including elemental, trivalent, and hexavalent chromium, and undergoes reduction-oxidation reactions in the environment. Since hexavalent chromium is known as a human carcinogen, it is most important to evaluate the oxidation-reduction characteristics of the hexavalent chromium species. Although hexavalent chromium can be reduced to trivalent state, the detailed information on this in workplace environments is limited. The purpose of this study was to investigate hexavalent chromium reduction in time in various conditions. A pilot chrome plating operation was prepared and operated in a laboratory for this study. There was evidence that the hexavalent chromium was reduced by time after mist generation. The percentage ratio (with 95% confidence intervals in parentheses) of hexavalent chromium to total chromium was almost 100% (99.1 approximately 102.3) immediately after mist generation, and was reduced to 87.4% (84.8 approximately 89.9) at 1 hour and 81.0% (78.3 approximately 83.5) at 2 hours, respectively. Another test indicated that hexavalent chromium collected on PVC filters was also reduced by time after sampling. Hexavalent chromium was reduced to 90.8% (88.2 approximately 93.3) at 2 hours after sampling. It also was found that hexavalent chromium was reduced during storage in air. It is recommended that air samples of hexavalent chromium be protected against reduction during storage."
1230935,Raber and  Greschonig 2000,New preconditioning strategy for the determination of inorganic anions with capillary zone electrophoresis using indirect UV detection,"It is widely accepted that preconditioning procedures are indispensable in capillary electrophoresis in order to achieve reproducibility of migration times and peak areas. Several preconditioning strategies have been employed for electrophoretic determinations of inorganic anions using indirect UV detection including simple flushing with buffer or alkaline or acid pre-rinsing followed by flushing with electrolyte. We investigated the influence of various preconditioning strategies on the reproducibility of migration times and peak areas of inorganic anions. The electrolyte systems for indirect UV detection were based on pyromellitic acid and chromic acid respectively as UV absorbing probes and hexamethonium hydroxide as electroosmatic flow modifier. Preconditioning agents under investigation were electrolyte buffer, NaOH, HCl and the free acids of the UV absorbing probes. Investigations showed that reproducibility of migration times and peak areas can be significantly improved by acid pre-rinsing using the corresponding acid of the UV absorbing probes compared to preconditioning by flushing the capillary with buffer. In contrast to acid pre-rinsing using hydrochloric acid no interfering signals within the migration time window of inorganic anions under investigation can be observed. The optimized preconditioning procedure yields relative standard deviations of migration times less than 0.25% (n = 10). Relative standard deviations of corrected peak areas were below 5% applying acid preconditioning using pyromellitic acid.","New preconditioning strategy for the determination of inorganic anions with capillary zone electrophoresis using indirect UV detection Abs: It is widely accepted that preconditioning procedures are indispensable in capillary electrophoresis in order to achieve reproducibility of migration times and peak areas. Several preconditioning strategies have been employed for electrophoretic determinations of inorganic anions using indirect UV detection including simple flushing with buffer or alkaline or acid pre-rinsing followed by flushing with electrolyte. We investigated the influence of various preconditioning strategies on the reproducibility of migration times and peak areas of inorganic anions. The electrolyte systems for indirect UV detection were based on pyromellitic acid and chromic acid respectively as UV absorbing probes and hexamethonium hydroxide as electroosmatic flow modifier. Preconditioning agents under investigation were electrolyte buffer, NaOH, HCl and the free acids of the UV absorbing probes. Investigations showed that reproducibility of migration times and peak areas can be significantly improved by acid pre-rinsing using the corresponding acid of the UV absorbing probes compared to preconditioning by flushing the capillary with buffer. In contrast to acid pre-rinsing using hydrochloric acid no interfering signals within the migration time window of inorganic anions under investigation can be observed. The optimized preconditioning procedure yields relative standard deviations of migration times less than 0.25% (n = 10). Relative standard deviations of corrected peak areas were below 5% applying acid preconditioning using pyromellitic acid."
1230934,Deveney and  Whittington 2001,A technique for preserving pigmentation in some capsalid monogeneans for taxonomic purposes,"A technique is described to preserve the pigment found in the bodies and the intestine of some brightly coloured and darkly pigmented benedeniine capsalid monogeneans. Previous studies of these pigmented capsalids have proven difficult because the pigmentation usually disappears when the worms are fixed using preservatives containing concentrations of formalin over 5% and/or ethanol, acetic acid, chromic acid, picric acid and mercuric chloride. The technique developed here uses a fixative comprising glycerol, acetone and formalin (GAF). After fixation under light coverslip compression for three minutes, specimens are transferred to absolute acetone for three minutes and cleared in a mixture of nine parts cedar wood oil and one part absolute acetone before mounting in Canada balsam. Processing must be carried out quickly, as these chemicals will cause the pigments to fade if the specimens are exposed to them for too long. Pigmented benedeniines processed using this technique retain the distribution, intensity and colour observed in live worms. The colour and distribution of pigmentation in monogeneans may be of taxonomic importance and this technique aids preparation of whole-mounts suitable for registration as type-material.","A technique for preserving pigmentation in some capsalid monogeneans for taxonomic purposes Abs: A technique is described to preserve the pigment found in the bodies and the intestine of some brightly coloured and darkly pigmented benedeniine capsalid monogeneans. Previous studies of these pigmented capsalids have proven difficult because the pigmentation usually disappears when the worms are fixed using preservatives containing concentrations of formalin over 5% and/or ethanol, acetic acid, chromic acid, picric acid and mercuric chloride. The technique developed here uses a fixative comprising glycerol, acetone and formalin (GAF). After fixation under light coverslip compression for three minutes, specimens are transferred to absolute acetone for three minutes and cleared in a mixture of nine parts cedar wood oil and one part absolute acetone before mounting in Canada balsam. Processing must be carried out quickly, as these chemicals will cause the pigments to fade if the specimens are exposed to them for too long. Pigmented benedeniines processed using this technique retain the distribution, intensity and colour observed in live worms. The colour and distribution of pigmentation in monogeneans may be of taxonomic importance and this technique aids preparation of whole-mounts suitable for registration as type-material."
1230932,Lie Ken Jie and  Alam 2001,Novel azido fatty acid ester derivatives from conjugated C(18) enynoate,"Methyl octadec-11Z-en-9-ynoate (1) was epoxidized to give methyl 11,12-Z-epoxy-octadec-9-ynoate (2, 81%). Acid catalyzed ring opening of the epoxy ring of compound 2 gave methyl 11,12-dihydroxy-octadec-9-ynoate (3, 80%). The latter was treated with mesyl chloride to yield methyl 11,12-dimesyloxy-octadec-9-ynoate (4, 76%). Reaction of compound 4 with sodium azide furnished methyl 11-azido-12-mesyloxy-octadec-9-ynoate (5a, 49%) and methyl 11-azido-octadec-11E-en-9-ynoate (5b, 24%). Compound 2 was semi-hydrogenated over Lindlar catalyst to give methyl 11,12-Z-epoxy-octadec-9Z-enoate (6, 90%). This allylic epoxy fatty ester (6) was reacted with sodium azide to give a mixture of methyl 11-azido-12-hydroxy-octadec-9Z-enoate (7a) and methyl 9-azido-12-hydroxy-octadec-9E-enoate (7b), which could not be separated into individual components by silica chromatography. Chromic acid oxidation of the mixture of compounds 7a and 7b furnished methyl 9-azido-12-oxo-octadec-10E-enoate (8, 42% based on amount of compound 6 used) and an intractable mixture of polar compounds. The various products were characterized by NMR spectroscopic and mass spectral analyses.","Novel azido fatty acid ester derivatives from conjugated C(18) enynoate Abs: Methyl octadec-11Z-en-9-ynoate (1) was epoxidized to give methyl 11,12-Z-epoxy-octadec-9-ynoate (2, 81%). Acid catalyzed ring opening of the epoxy ring of compound 2 gave methyl 11,12-dihydroxy-octadec-9-ynoate (3, 80%). The latter was treated with mesyl chloride to yield methyl 11,12-dimesyloxy-octadec-9-ynoate (4, 76%). Reaction of compound 4 with sodium azide furnished methyl 11-azido-12-mesyloxy-octadec-9-ynoate (5a, 49%) and methyl 11-azido-octadec-11E-en-9-ynoate (5b, 24%). Compound 2 was semi-hydrogenated over Lindlar catalyst to give methyl 11,12-Z-epoxy-octadec-9Z-enoate (6, 90%). This allylic epoxy fatty ester (6) was reacted with sodium azide to give a mixture of methyl 11-azido-12-hydroxy-octadec-9Z-enoate (7a) and methyl 9-azido-12-hydroxy-octadec-9E-enoate (7b), which could not be separated into individual components by silica chromatography. Chromic acid oxidation of the mixture of compounds 7a and 7b furnished methyl 9-azido-12-oxo-octadec-10E-enoate (8, 42% based on amount of compound 6 used) and an intractable mixture of polar compounds. The various products were characterized by NMR spectroscopic and mass spectral analyses."
1230930,Katayama et al. 2001,Histoplasmosis in the lung of a race horse with yersiniosis,"A 4-year-old female thoroughbred race horse died of acute peritonitis caused by necrotizing granulomatous duodenitis. Yersinia enterocolitica was immunohistochemically demonstrated in macrophages in granulomas developed in the duodenum, lung, liver and abdominal lymph nodes. The yeast-like fungi were found in the cytoplasmic vacuoles of macrophages in the lung that infiltrated into the granulomas and surrounding alveoli with congestive edema. The yeast-like fungi were positively stained by Gomori-Grocott chromic acid methenamine silver stain and immuno-histochemically stained with anti-histoplasma antibody. In this case, it was considered that granulomas formed in the duodenum, lung, liver and abdominal lymph nodes were primarily caused by Yersinia enterocolitica due to idiopathic weakening of the immune system. Yeast-like fungi immunohistochemically identified as histoplasmas secondarily infected the lung. This is the first case regarded as equine histoplasmosis capsulati in Japan.","Histoplasmosis in the lung of a race horse with yersiniosis Abs: A 4-year-old female thoroughbred race horse died of acute peritonitis caused by necrotizing granulomatous duodenitis. Yersinia enterocolitica was immunohistochemically demonstrated in macrophages in granulomas developed in the duodenum, lung, liver and abdominal lymph nodes. The yeast-like fungi were found in the cytoplasmic vacuoles of macrophages in the lung that infiltrated into the granulomas and surrounding alveoli with congestive edema. The yeast-like fungi were positively stained by Gomori-Grocott chromic acid methenamine silver stain and immuno-histochemically stained with anti-histoplasma antibody. In this case, it was considered that granulomas formed in the duodenum, lung, liver and abdominal lymph nodes were primarily caused by Yersinia enterocolitica due to idiopathic weakening of the immune system. Yeast-like fungi immunohistochemically identified as histoplasmas secondarily infected the lung. This is the first case regarded as equine histoplasmosis capsulati in Japan."
1230928,Denk et al. 2002,Impurity profiling of pholcodine by liquid chromatography electrospray ionization mass spectrometry (LC-ESI-MS),"Previously, a dimorpholinoethyl pholcodine manufacturing impurity was reported to be present in some samples of pholcodine. Apart from this impurity and morphine, other unknown impurities were detected in all the samples analysed by HPLC and micellar electrokinetic capillary chromatography. In this study, liquid chromatography mass spectrometry (LC-MS) analysis of samples of pholcodine showed that two of the previously unidentified compounds had mass spectra with molecular ions which differed from pholcodine by 16 amu. From this observation and other experimental data it was concluded that they are hydroxy derivatives of pholcodine. 10-S-hydroxy-pholcodine, which was synthesized by the oxidation of pholcodine with chromic acid, had the same chromatographic properties as one of these compounds. An early eluting compound in the LC-MS chromatograms of pholcodine was identified as pholcodine-N-oxide by matching chromatographic and mass spectral data of a synthesized pholcodine-N-oxide standard. The reaction of pholcodine with m-chloroperoxybenzoic acid not only produced the mono N-oxide, but also pholcodine-di-N,N'-oxide.","Impurity profiling of pholcodine by liquid chromatography electrospray ionization mass spectrometry (LC-ESI-MS) Abs: Previously, a dimorpholinoethyl pholcodine manufacturing impurity was reported to be present in some samples of pholcodine. Apart from this impurity and morphine, other unknown impurities were detected in all the samples analysed by HPLC and micellar electrokinetic capillary chromatography. In this study, liquid chromatography mass spectrometry (LC-MS) analysis of samples of pholcodine showed that two of the previously unidentified compounds had mass spectra with molecular ions which differed from pholcodine by 16 amu. From this observation and other experimental data it was concluded that they are hydroxy derivatives of pholcodine. 10-S-hydroxy-pholcodine, which was synthesized by the oxidation of pholcodine with chromic acid, had the same chromatographic properties as one of these compounds. An early eluting compound in the LC-MS chromatograms of pholcodine was identified as pholcodine-N-oxide by matching chromatographic and mass spectral data of a synthesized pholcodine-N-oxide standard. The reaction of pholcodine with m-chloroperoxybenzoic acid not only produced the mono N-oxide, but also pholcodine-di-N,N'-oxide."
1230927,Kuo and  Wang 2002,Effect of rise distance on droplets generated from bubble bursting on the surface of chromic acid solutions,"In the processes of chromium electroplating, bursting bubbles are the major sources of chromium droplets that may lead to nasal septum disorders among workers. The gas bubbles form as a result of electrochemical reactions on the surfaces of pieces being plated, rise through the liquid, and then burst into droplets at liquid surfaces. The dimensions of the pieces being plated differ from piece to piece, and therefore the rise distance of the bubbles varies. This study is aimed at evaluating the effect of rise distance on the characteristics of droplets generated from bubbles bursting on the surface of chromic acid solutions by an experimental bubbling system. Two rise distances, 15 and 30 cm, were tested. An aerodynamic particle sizer was used to determine the droplet size distribution over the range of 0.8-30 microm. A Marple personal impactor was employed to collect droplet samples on polyvinyl chloride filters for Cr(VI) analysis. It was found that the Cr(VI) concentrations in droplets increased when the bubble rise distance increased. The result suggests that soluble ions such as Cr(VI) are scavenged by rising bubbles.","Effect of rise distance on droplets generated from bubble bursting on the surface of chromic acid solutions Abs: In the processes of chromium electroplating, bursting bubbles are the major sources of chromium droplets that may lead to nasal septum disorders among workers. The gas bubbles form as a result of electrochemical reactions on the surfaces of pieces being plated, rise through the liquid, and then burst into droplets at liquid surfaces. The dimensions of the pieces being plated differ from piece to piece, and therefore the rise distance of the bubbles varies. This study is aimed at evaluating the effect of rise distance on the characteristics of droplets generated from bubbles bursting on the surface of chromic acid solutions by an experimental bubbling system. Two rise distances, 15 and 30 cm, were tested. An aerodynamic particle sizer was used to determine the droplet size distribution over the range of 0.8-30 microm. A Marple personal impactor was employed to collect droplet samples on polyvinyl chloride filters for Cr(VI) analysis. It was found that the Cr(VI) concentrations in droplets increased when the bubble rise distance increased. The result suggests that soluble ions such as Cr(VI) are scavenged by rising bubbles."
1230926,Erkan et al. 2002,Comparative ultracytochemical study of the acrosome in four different Veneroida species from the Turkish coast,"Cytoplasmic acidic phosphoproteins and complex polysaccharides were stained with ammoniacal silver nitrate-formalin and phosphotungstic acid-chromic acid, respectively. In Cerastoderma glaucum (Cardiacea), acrosomal vesicle contents are differentiated into an apical intermediate-dense component and a basal dense region. PTA stained the apical component and silver stained the basal region and the apex of the acrosome. In Spisula subtruncata (Mactracea) the acrosome showed a PTA-stained apical component and a silver-positive basal dense region. In the Veneracea, Chamelea gallina and Pitar rudis show a tripartite acrosomal vesicle, with apical light, outer dense and inner intermediate-dense regions. In both species, the apical and inner components were stained by PTA, whereas silver stained all regions of the acrosomal vesicle in C. gallina and the apical and outer regions in P. rudis. In midpiece, only C. glaucum showed a positive silver reaction at the centriolar fossa.","Comparative ultracytochemical study of the acrosome in four different Veneroida species from the Turkish coast Abs: Cytoplasmic acidic phosphoproteins and complex polysaccharides were stained with ammoniacal silver nitrate-formalin and phosphotungstic acid-chromic acid, respectively. In Cerastoderma glaucum (Cardiacea), acrosomal vesicle contents are differentiated into an apical intermediate-dense component and a basal dense region. PTA stained the apical component and silver stained the basal region and the apex of the acrosome. In Spisula subtruncata (Mactracea) the acrosome showed a PTA-stained apical component and a silver-positive basal dense region. In the Veneracea, Chamelea gallina and Pitar rudis show a tripartite acrosomal vesicle, with apical light, outer dense and inner intermediate-dense regions. In both species, the apical and inner components were stained by PTA, whereas silver stained all regions of the acrosomal vesicle in C. gallina and the apical and outer regions in P. rudis. In midpiece, only C. glaucum showed a positive silver reaction at the centriolar fossa."
1230925,Tracy and  Walia 2002,A method to fix lipids for staining fat embolism in paraffin sections,"<strong>AIMS: </strong>To develop a method to preserve lipids in formalin-fixed tissues for staining in paraffin sections, and to illustrate its use in lung and brain of a fat embolism case, and in examples of fatty liver and atheroma.<br /><br /><strong>METHODS AND RESULTS: </strong>A saturated solution of linoleic acid in 70% ethylene glycol was prepared and tissues were exposed to this for 3 days at 56 degrees C. These tissues were treated with 2% chromic acid at 4 degrees C for 24 h followed by 24 h in 5% sodium bicarbonate, with appropriate rinsing between solutions. Paraffin sections of these tissues were stained with a lipid-soluble dye such as Oil Red O. Examples of fat embolism, fatty liver, and atheroma were shown photographically as illustrations of expected results.<br /><br /><strong>CONCLUSIONS: </strong>The demonstration of fat embolism with good quality tissue detail is made practical by the method, which is convenient and inexpensive. The method appears to be generally applicable to tissue lipids of various sorts, as exemplified by adipose tissue, fatty liver, and atheroma.","A method to fix lipids for staining fat embolism in paraffin sections Abs: <strong>AIMS: </strong>To develop a method to preserve lipids in formalin-fixed tissues for staining in paraffin sections, and to illustrate its use in lung and brain of a fat embolism case, and in examples of fatty liver and atheroma.<br /><br /><strong>METHODS AND RESULTS: </strong>A saturated solution of linoleic acid in 70% ethylene glycol was prepared and tissues were exposed to this for 3 days at 56 degrees C. These tissues were treated with 2% chromic acid at 4 degrees C for 24 h followed by 24 h in 5% sodium bicarbonate, with appropriate rinsing between solutions. Paraffin sections of these tissues were stained with a lipid-soluble dye such as Oil Red O. Examples of fat embolism, fatty liver, and atheroma were shown photographically as illustrations of expected results.<br /><br /><strong>CONCLUSIONS: </strong>The demonstration of fat embolism with good quality tissue detail is made practical by the method, which is convenient and inexpensive. The method appears to be generally applicable to tissue lipids of various sorts, as exemplified by adipose tissue, fatty liver, and atheroma."
1230924,Kabir-ud-Din et al. 2002,Influence of sodium dodecyl sulfate/TritonX-100 micelles on the oxidation of D-fructose by chromic acid in presence of HClO(4),"The kinetics of oxidation of D-fructose by chromic acid in aqueous and aqueous surfactant (sodium dodecyl sulfate, SDS, and alkylphenyl polyethylenglykol, TX-100) media have been investigated in the presence of HClO(4). The reaction is acid catalyzed and is associated with an induction period which is dependent on [H(+)], [surfactant] and temperature. The order of oxidation during induction under [D-fructose]&gt;[chromic acid] conditions is fractional in each reagent in both media. The rate constant was found to increase with [Mn(II)]. A mechanism has been proposed for the reaction. The micelles produce a catalytic effect in the range of SDS and TX-100 concentrations used, and the effect is explained by means of the pseudo-phase mass-action model. In the presence of SDS, the reaction is inhibited by electrolytes (NH(4)Br, NaBr, LiBr), and the inhibition order Na(+)&gt;Li(+)&gt;NH(4)(+) is explained on the basis of electrostatic considerations. The rate constant (k(m)), binding constants (K(S) and K(F)), and corresponding activation parameters (E(a), delta H( not equal ) and delta S( not equal )) have been evaluated and discussed. The order of reactivities of different sugars is found as: D-fructose&gt;D-arabinose&gt;D-xylose approximately D-glucose.","Influence of sodium dodecyl sulfate/TritonX-100 micelles on the oxidation of D-fructose by chromic acid in presence of HClO(4) Abs: The kinetics of oxidation of D-fructose by chromic acid in aqueous and aqueous surfactant (sodium dodecyl sulfate, SDS, and alkylphenyl polyethylenglykol, TX-100) media have been investigated in the presence of HClO(4). The reaction is acid catalyzed and is associated with an induction period which is dependent on [H(+)], [surfactant] and temperature. The order of oxidation during induction under [D-fructose]&gt;[chromic acid] conditions is fractional in each reagent in both media. The rate constant was found to increase with [Mn(II)]. A mechanism has been proposed for the reaction. The micelles produce a catalytic effect in the range of SDS and TX-100 concentrations used, and the effect is explained by means of the pseudo-phase mass-action model. In the presence of SDS, the reaction is inhibited by electrolytes (NH(4)Br, NaBr, LiBr), and the inhibition order Na(+)&gt;Li(+)&gt;NH(4)(+) is explained on the basis of electrostatic considerations. The rate constant (k(m)), binding constants (K(S) and K(F)), and corresponding activation parameters (E(a), delta H( not equal ) and delta S( not equal )) have been evaluated and discussed. The order of reactivities of different sugars is found as: D-fructose&gt;D-arabinose&gt;D-xylose approximately D-glucose."
1230923,Sadhra et al. 2002,Workers' understanding of chemical risks: electroplating case study,"<strong>BACKGROUND: </strong>There is limited research concerning how small companies in particular, respond to health and safety messages.<br /><br /><strong>AIMS: </strong>To understand individuals' knowledge and beliefs about chemical risks and to compare these with those of experts.<br /><br /><strong>METHODS: </strong>The use of chromic acid in particular, and also other chemicals associated with chrome plating were studied. All chromium plating firms were based in the West Midlands. The methodology involved initial face to face interviews (n = 21) with chromium platers, structured questionnaires (n = 84) to test the prevalence of beliefs identified in the interviews, an expert questionnaire, and a workshop to discuss findings. The responses of platers were compared with those of occupational health and safety experts.<br /><br /><strong>RESULTS: </strong>Although chromium platers appeared to understand the short term adverse effects of the chemicals to which they are exposed, their understanding of long term, or chronic effects appeared to be incomplete. They had good knowledge of acute effects based primarily on experience. Platers were aware of the hazardous nature of the chemicals with which they work, but did not draw distinction between the terms &quot;hazards&quot; and &quot;risks&quot;. They had difficulties articulating the effects of the chemicals and how exposure might occur; although it is inappropriate to equate this with lack of knowledge. A significant minority of platers displayed deficiencies in understanding key technical terms used in Safety Data Sheets.<br /><br /><strong>CONCLUSIONS: </strong>This study provides a method which can be used to gain some understanding of workers' knowledge and beliefs about risks that they are exposed to in the workplace. The study also identifies gaps between the platers' knowledge and beliefs and those of experts. New risk information needs to be designed which addresses the information needs of platers using language that they understand.","Workers' understanding of chemical risks: electroplating case study Abs: <strong>BACKGROUND: </strong>There is limited research concerning how small companies in particular, respond to health and safety messages.<br /><br /><strong>AIMS: </strong>To understand individuals' knowledge and beliefs about chemical risks and to compare these with those of experts.<br /><br /><strong>METHODS: </strong>The use of chromic acid in particular, and also other chemicals associated with chrome plating were studied. All chromium plating firms were based in the West Midlands. The methodology involved initial face to face interviews (n = 21) with chromium platers, structured questionnaires (n = 84) to test the prevalence of beliefs identified in the interviews, an expert questionnaire, and a workshop to discuss findings. The responses of platers were compared with those of occupational health and safety experts.<br /><br /><strong>RESULTS: </strong>Although chromium platers appeared to understand the short term adverse effects of the chemicals to which they are exposed, their understanding of long term, or chronic effects appeared to be incomplete. They had good knowledge of acute effects based primarily on experience. Platers were aware of the hazardous nature of the chemicals with which they work, but did not draw distinction between the terms &quot;hazards&quot; and &quot;risks&quot;. They had difficulties articulating the effects of the chemicals and how exposure might occur; although it is inappropriate to equate this with lack of knowledge. A significant minority of platers displayed deficiencies in understanding key technical terms used in Safety Data Sheets.<br /><br /><strong>CONCLUSIONS: </strong>This study provides a method which can be used to gain some understanding of workers' knowledge and beliefs about risks that they are exposed to in the workplace. The study also identifies gaps between the platers' knowledge and beliefs and those of experts. New risk information needs to be designed which addresses the information needs of platers using language that they understand."
1230922,McCrary 2002,Persistent nasal ulcer,,Persistent nasal ulcer Abs: 
1230921,Jha and  Chugh 2003,"Nephropathy associated with animal, plant, and chemical toxins in the tropics","Widespread human exposure to a variety of drugs, chemicals, and biologic products and recent awareness of their toxic manifestations has led to the recognition of toxic nephropathy as an important segment of renal disease in the tropical countries. Tropical nephrotoxins are distinctly different from those seen in the rest of the world and are derived from local fauna and flora or plant and chemical sources. The spectrum of exposure varies from country to country and even from community to community, depending on variations in the distribution of local plants and animal species and prevalent social practices. Acute renal failure (ARF), either alone or in association with liver failure, neurologic abnormalities, metabolic acidosis, disseminated intravascular coagulation, or pulmonary infections is the most common form of presentation. Traditional medicines prescribed by witch doctors (traditional healers) constitute a special class of nephrotoxins among several communities in Africa and Asia. The prevalence of nephropathy caused by traditional medicines is directly related to a combination of ignorance, poverty, lack of medical facilities, lax legislation, and widespread belief in indigenous systems of medicine in rural areas. These medicines are a mix of herbs and unknown chemicals administered orally or as enemas. Clustering of cases after exposure to a particular agent suggests the possibility of a toxic insult. Common animal nephrotoxins are venoms of viper snakes, sea snakes, stinging insects, and raw gallbladder and bile of carp and sheep. Botanical nephrotoxins are encountered both in common edible plants (djenkol beans, mushrooms) and medicinal herbs (impila, cat's claw). Mistaken identification of medicinal herbs by untrained workers and even deliberate trials of toxic substitutes derived from plants frequently lead to renal disease, the most commonly reported being the Chinese herbal nephropathy. Nephrotoxicity caused by chemicals can be secondary to accidental occupational exposure in industrial work places (eg, chromic acid), or after suicidal or homicidal use (eg, copper sulphate, ethylene dibromide, ethylene glycol). Late presentation and multiorgan dysfunction are associated with a high mortality. A high index of suspicion, careful history taking, and an awareness of local practices are essential for proper diagnosis and management of toxic nephropathies in the tropics.","Nephropathy associated with animal, plant, and chemical toxins in the tropics Abs: Widespread human exposure to a variety of drugs, chemicals, and biologic products and recent awareness of their toxic manifestations has led to the recognition of toxic nephropathy as an important segment of renal disease in the tropical countries. Tropical nephrotoxins are distinctly different from those seen in the rest of the world and are derived from local fauna and flora or plant and chemical sources. The spectrum of exposure varies from country to country and even from community to community, depending on variations in the distribution of local plants and animal species and prevalent social practices. Acute renal failure (ARF), either alone or in association with liver failure, neurologic abnormalities, metabolic acidosis, disseminated intravascular coagulation, or pulmonary infections is the most common form of presentation. Traditional medicines prescribed by witch doctors (traditional healers) constitute a special class of nephrotoxins among several communities in Africa and Asia. The prevalence of nephropathy caused by traditional medicines is directly related to a combination of ignorance, poverty, lack of medical facilities, lax legislation, and widespread belief in indigenous systems of medicine in rural areas. These medicines are a mix of herbs and unknown chemicals administered orally or as enemas. Clustering of cases after exposure to a particular agent suggests the possibility of a toxic insult. Common animal nephrotoxins are venoms of viper snakes, sea snakes, stinging insects, and raw gallbladder and bile of carp and sheep. Botanical nephrotoxins are encountered both in common edible plants (djenkol beans, mushrooms) and medicinal herbs (impila, cat's claw). Mistaken identification of medicinal herbs by untrained workers and even deliberate trials of toxic substitutes derived from plants frequently lead to renal disease, the most commonly reported being the Chinese herbal nephropathy. Nephrotoxicity caused by chemicals can be secondary to accidental occupational exposure in industrial work places (eg, chromic acid), or after suicidal or homicidal use (eg, copper sulphate, ethylene dibromide, ethylene glycol). Late presentation and multiorgan dysfunction are associated with a high mortality. A high index of suspicion, careful history taking, and an awareness of local practices are essential for proper diagnosis and management of toxic nephropathies in the tropics."
1230919,Lie Ken Jie et al. 2003,Novel halo-oxo-allenic fatty ester derivatives from epoxidized methyl santalbate (methyl trans-11-octadecen-9-ynoate),"Methyl santalbate (methyl trans-11-octadecen-9-ynoate) from Sandal wood seed oil, Santalbum alum) was epoxidized to methyl trans-11,12-epoxy-octadec-9-ynoate (1). Treatment of compound 1 with tetrabutylammonium dihydrogentrifluoride, and boron trifluoride etherate gave the corresponding anti- (2a) (57%) and syn- (2b) (35%) fluorohydrin derivatives, respectively. These reactions were regio- and stereoselective in nature. The structures of the anti- and syn- isomers were confirmed by NMR spectroscopy. Ring opening of the epoxy system of compound 1 with lithium chloride gave the anti-chlorohydrin derivative (3) (89%). Oxidation of either compound 2a or 2b gave the same fluoro-keto acetylenic fatty ester (4) (75%), and compound 3 on chromic acid oxidation yielded the corresponding chloro-keto acetylene (5) (73%). Isomerization of compounds 4 and 5 with potassium carbonate in dichloromethane furnished the requisite fluoro-allenic (6) (63%, methyl 11-fluoro-12-oxo-9,10-octadecadienoate) and chloro-allenic (7) (80%, methyl 11-chloro-12-oxo-9,10-octadecadienoate) C(18) fatty esters. All products were confirmed by a combination of spectrometric and spectroscopic techniques.","Novel halo-oxo-allenic fatty ester derivatives from epoxidized methyl santalbate (methyl trans-11-octadecen-9-ynoate) Abs: Methyl santalbate (methyl trans-11-octadecen-9-ynoate) from Sandal wood seed oil, Santalbum alum) was epoxidized to methyl trans-11,12-epoxy-octadec-9-ynoate (1). Treatment of compound 1 with tetrabutylammonium dihydrogentrifluoride, and boron trifluoride etherate gave the corresponding anti- (2a) (57%) and syn- (2b) (35%) fluorohydrin derivatives, respectively. These reactions were regio- and stereoselective in nature. The structures of the anti- and syn- isomers were confirmed by NMR spectroscopy. Ring opening of the epoxy system of compound 1 with lithium chloride gave the anti-chlorohydrin derivative (3) (89%). Oxidation of either compound 2a or 2b gave the same fluoro-keto acetylenic fatty ester (4) (75%), and compound 3 on chromic acid oxidation yielded the corresponding chloro-keto acetylene (5) (73%). Isomerization of compounds 4 and 5 with potassium carbonate in dichloromethane furnished the requisite fluoro-allenic (6) (63%, methyl 11-fluoro-12-oxo-9,10-octadecadienoate) and chloro-allenic (7) (80%, methyl 11-chloro-12-oxo-9,10-octadecadienoate) C(18) fatty esters. All products were confirmed by a combination of spectrometric and spectroscopic techniques."
1230918,Carlton 2003,Hexavalent chromium exposures during full-aircraft corrosion control,"Aluminum alloys used in the construction of modern aircraft are subject to corrosion. The principal means of controlling this corrosion in the U.S. Air Force are organic coatings. The organic coating system consists of a chromate conversion coat, epoxy resin primer, and polyurethane enamel topcoat. Hexavalent chromium (CrVI) is present in the conversion coat in the form of chromic acid and in the primer in the form of strontium chromate. CrVI inhalation exposures can occur when workers spray conversion coat onto bare metal and apply primer to the treated metal surface. In addition, mechanical abrasion of aircraft surfaces can generate particulates that contain chromates from previously applied primers and conversion coats. This study measured CrVI exposures during these corrosion control procedures. Mean time-weighted average (TWA) exposure to chromic acid during conversion coat treatment was 0.48 microg/m(3), below the current American Conference of Governmental Industrial Hygienists (ACGIH) threshold limit value (TLV(R)) TWA of 50 microg/m(3) for water-soluble CrVI compounds. Mean TWA exposures to strontium chromate were 5.33 microg/m(3) during mechanical abrasion and 83.8 microg/m(3) during primer application. These levels are in excess of the current ACGIH TLV-TWA of 0.5 microg/m(3) for strontium chromate. In the absence of a change from chromated to nonchromated conversion coats and primers, additional control measures are needed to reduce these exposures.","Hexavalent chromium exposures during full-aircraft corrosion control Abs: Aluminum alloys used in the construction of modern aircraft are subject to corrosion. The principal means of controlling this corrosion in the U.S. Air Force are organic coatings. The organic coating system consists of a chromate conversion coat, epoxy resin primer, and polyurethane enamel topcoat. Hexavalent chromium (CrVI) is present in the conversion coat in the form of chromic acid and in the primer in the form of strontium chromate. CrVI inhalation exposures can occur when workers spray conversion coat onto bare metal and apply primer to the treated metal surface. In addition, mechanical abrasion of aircraft surfaces can generate particulates that contain chromates from previously applied primers and conversion coats. This study measured CrVI exposures during these corrosion control procedures. Mean time-weighted average (TWA) exposure to chromic acid during conversion coat treatment was 0.48 microg/m(3), below the current American Conference of Governmental Industrial Hygienists (ACGIH) threshold limit value (TLV(R)) TWA of 50 microg/m(3) for water-soluble CrVI compounds. Mean TWA exposures to strontium chromate were 5.33 microg/m(3) during mechanical abrasion and 83.8 microg/m(3) during primer application. These levels are in excess of the current ACGIH TLV-TWA of 0.5 microg/m(3) for strontium chromate. In the absence of a change from chromated to nonchromated conversion coats and primers, additional control measures are needed to reduce these exposures."
1230917,Acharya et al. 2004,Potential role of vitamins in chromium induced spermatogenesis in Swiss mice,"Chromium (Cr) (VI) compounds are known carcinogens and mutagens. The mechanism of carcinogenicity and mutagenicity caused by chromium(VI) compounds remained unclear for several years. However, in the recent past chromium-induced carcinogenicity and/or mutagenicity was known to happen due to the generation of reactive oxygen species (ROS). In the present context, chromic acid (CrO(3)), a potential Cr(VI) compound could be able to generate reactive oxygen radicals in the testes of Swiss mice as evidenced from significantly higher lipid peroxidation compared to untreated controls. The cytotoxic effects of the compound on the testes are depicted in terms of significantly reduced sperm count level accompanied with increased abnormal sperm population in treated mice. Supplementation of vitamins like Vitamin C and Vitamin E (Vit C and Vit E) to CrO(3) injected mice groups could partially prevent the incidence of abnormal sperm population and increased the sperm count. Of the two vitamins, taken for the study, Vit C happens to be more effective in ameliorating germ cells from degeneration and from mutation to abnormal sperm. Possible antioxidative role of both the vitamins have been studied for significant decrease in lipid peroxidation associated with marked elevation in sperm count level and significant decrease in the percentage of abnormal sperm formation in CrO(3)-treated mice.","Potential role of vitamins in chromium induced spermatogenesis in Swiss mice Abs: Chromium (Cr) (VI) compounds are known carcinogens and mutagens. The mechanism of carcinogenicity and mutagenicity caused by chromium(VI) compounds remained unclear for several years. However, in the recent past chromium-induced carcinogenicity and/or mutagenicity was known to happen due to the generation of reactive oxygen species (ROS). In the present context, chromic acid (CrO(3)), a potential Cr(VI) compound could be able to generate reactive oxygen radicals in the testes of Swiss mice as evidenced from significantly higher lipid peroxidation compared to untreated controls. The cytotoxic effects of the compound on the testes are depicted in terms of significantly reduced sperm count level accompanied with increased abnormal sperm population in treated mice. Supplementation of vitamins like Vitamin C and Vitamin E (Vit C and Vit E) to CrO(3) injected mice groups could partially prevent the incidence of abnormal sperm population and increased the sperm count. Of the two vitamins, taken for the study, Vit C happens to be more effective in ameliorating germ cells from degeneration and from mutation to abnormal sperm. Possible antioxidative role of both the vitamins have been studied for significant decrease in lipid peroxidation associated with marked elevation in sperm count level and significant decrease in the percentage of abnormal sperm formation in CrO(3)-treated mice."
1230915,Pokkuluri et al. 2004,Family of cytochrome c7-type proteins from Geobacter sulfurreducens: structure of one cytochrome c7 at 1.45 A resolution,"The structure of a cytochrome c(7) (PpcA) from Geobacter sulfurreducens was determined by X-ray diffraction at 1.45 A resolution; the R factor is 18.2%. The protein contains a three-heme core that is surrounded by 71 amino acid residues. An unusual feature of this cytochrome is that it has 17 lysine residues, but only nine hydrophobic residues that are larger than alanine. The details of the structure are described and compared with those of cytochrome c(7) from Desulfuromonas acetoxidans and with cytochromes c(3). The two cytochrome c(7) molecules have sequences that are 46% identical, but the arrangements of the hemes in the two structures differ; the rms deviation of all alpha-carbons is 2.5 A. These cytochromes can reduce various metal ions. The reduction site of the chromate ion in D. acetoxidans is occupied by a sulfate ion in the crystal structure of PpcA. We identified four additional homologues of cytochrome c(7) in the G. sulfurreducens genome and three polymers of c(7)-type domains. Of the polymers, two have four repeats and one has nine repeats. On the basis of sequence alignments, one of the hemes in each of the cytochrome c(7)-type domains does not have the bis-histidine coordination. The packing of the molecules in the crystal structure of PpcA suggests that the polymers have an elongated conformation and might form a &quot;nanowire&quot;.","Family of cytochrome c7-type proteins from Geobacter sulfurreducens: structure of one cytochrome c7 at 1.45 A resolution Abs: The structure of a cytochrome c(7) (PpcA) from Geobacter sulfurreducens was determined by X-ray diffraction at 1.45 A resolution; the R factor is 18.2%. The protein contains a three-heme core that is surrounded by 71 amino acid residues. An unusual feature of this cytochrome is that it has 17 lysine residues, but only nine hydrophobic residues that are larger than alanine. The details of the structure are described and compared with those of cytochrome c(7) from Desulfuromonas acetoxidans and with cytochromes c(3). The two cytochrome c(7) molecules have sequences that are 46% identical, but the arrangements of the hemes in the two structures differ; the rms deviation of all alpha-carbons is 2.5 A. These cytochromes can reduce various metal ions. The reduction site of the chromate ion in D. acetoxidans is occupied by a sulfate ion in the crystal structure of PpcA. We identified four additional homologues of cytochrome c(7) in the G. sulfurreducens genome and three polymers of c(7)-type domains. Of the polymers, two have four repeats and one has nine repeats. On the basis of sequence alignments, one of the hemes in each of the cytochrome c(7)-type domains does not have the bis-histidine coordination. The packing of the molecules in the crystal structure of PpcA suggests that the polymers have an elongated conformation and might form a &quot;nanowire&quot;."
1230913,Tracy and  Walia 2004,Lipid fixation for fat staining in paraffin sections applied to lesions of atherosclerosis,"A new method to fix lipids for staining in paraffin sections was applied here to early lesions of atherosclerosis to test comparability with similar results using frozen-section fat stains. Small blocks of formalin-fixed human coronary artery were exposed to an emulsion of linoleic acid and lecithin in 70% ethylene glycol at 56 degrees C for 3 days. The unsaturated fatty acids partitioned into the tissue lipids for later fixation by chromic acid and could then be processed through paraffin-section for fat staining. Blocks of tissue from the same specimens were also processed for standard frozen-section fat staining. The types of early atherosclerotic lesions described by the American Heart Association Lesions Committee--types I, II, III, and IV--were demonstrated equally well using the two methods. Additional newly described patterns of lipid deposits were also revealed by both methods. The paraffin method showed no indication of omitting or adding anything compared with frozen sections. The surprising finding of unexpected patterns of lipid distribution in human coronary artery suggests that the method may prove to be useful. Those novel patterns were first observed with the more flexible paraffin method and later confirmed by the more tedious and demanding frozen-section method.","Lipid fixation for fat staining in paraffin sections applied to lesions of atherosclerosis Abs: A new method to fix lipids for staining in paraffin sections was applied here to early lesions of atherosclerosis to test comparability with similar results using frozen-section fat stains. Small blocks of formalin-fixed human coronary artery were exposed to an emulsion of linoleic acid and lecithin in 70% ethylene glycol at 56 degrees C for 3 days. The unsaturated fatty acids partitioned into the tissue lipids for later fixation by chromic acid and could then be processed through paraffin-section for fat staining. Blocks of tissue from the same specimens were also processed for standard frozen-section fat staining. The types of early atherosclerotic lesions described by the American Heart Association Lesions Committee--types I, II, III, and IV--were demonstrated equally well using the two methods. Additional newly described patterns of lipid deposits were also revealed by both methods. The paraffin method showed no indication of omitting or adding anything compared with frozen sections. The surprising finding of unexpected patterns of lipid distribution in human coronary artery suggests that the method may prove to be useful. Those novel patterns were first observed with the more flexible paraffin method and later confirmed by the more tedious and demanding frozen-section method."
1230911,Lin and  Tseng 2001,Surface characterization and platelet adhesion studies on polyethylene surface with hirudin immobilization,"Hirudin, a protein composed of 65 or 66 amino acid, is a newly risen anticoagulant agent and has been considered as the most potent thrombin inhibitor. Hirudin can block the active site of thrombin by means of its carboxylic acid reaction with the active regime of thrombin, and becomes a tightly bound complex, and thus controls the formation of thrombus. Hirudin was covalently immobilized onto the water-soluble carbodiimide preactivated and chromic acid oxidized PE surface. Surface chemistry analysis indicated that a certain amount of carboxylic acid groups was generated on the polyethylene surface after oxidation with chromic acid solution. The amount of carboxylic acid functional group increased with the oxidation time. In addition, polyethylene surface was etched by chromic acid solution, and a rougher surface was created. The morphology of oxidized polyethylene surface was similar to each other among the samples with oxidation time from 1 to 8 min. ESCA results indicated the number of hirudin molecules immobilized was constant at the reaction time studied. In vitro platelet adhesion assay indicated the number of adhered platelets on the oxidized polyethylene surface increased significantly after oxidation. In contrast, surface with hirudin immobilization showed a reduction in adhered platelet density than the chromic acid oxidized counterpart due to the decrease of platelet-activating capability by the hirudin-thrombin complex and the differences in the adsorbed protein composition.","Surface characterization and platelet adhesion studies on polyethylene surface with hirudin immobilization Abs: Hirudin, a protein composed of 65 or 66 amino acid, is a newly risen anticoagulant agent and has been considered as the most potent thrombin inhibitor. Hirudin can block the active site of thrombin by means of its carboxylic acid reaction with the active regime of thrombin, and becomes a tightly bound complex, and thus controls the formation of thrombus. Hirudin was covalently immobilized onto the water-soluble carbodiimide preactivated and chromic acid oxidized PE surface. Surface chemistry analysis indicated that a certain amount of carboxylic acid groups was generated on the polyethylene surface after oxidation with chromic acid solution. The amount of carboxylic acid functional group increased with the oxidation time. In addition, polyethylene surface was etched by chromic acid solution, and a rougher surface was created. The morphology of oxidized polyethylene surface was similar to each other among the samples with oxidation time from 1 to 8 min. ESCA results indicated the number of hirudin molecules immobilized was constant at the reaction time studied. In vitro platelet adhesion assay indicated the number of adhered platelets on the oxidized polyethylene surface increased significantly after oxidation. In contrast, surface with hirudin immobilization showed a reduction in adhered platelet density than the chromic acid oxidized counterpart due to the decrease of platelet-activating capability by the hirudin-thrombin complex and the differences in the adsorbed protein composition."
1230910,Hofsté et al. 1998,The effect of chromic acid treatment on the mechanical and tribological properties of aramid fibre reinforced ultra-high molecular weight polyethylene composite,"Surface oxidation of ultra-high molecular weight polyethylene (UHMWPE) powder has an influence on the mixing procedure of chopped fibres and UHMWPE powder. Due to this oxidation hydrogen bonds can be formed between the fibres and powder particles, leading to a more homogeneous fibre-powder mixture. This treatment improves the fibre-matrix interface and thus the physical properties of the composite. Chromic acid treatment also has an influence on the mechanical and tribological properties of the aramid-UHMWPE composite. Although only a relatively small improvement is observed in the modulus, yield stress and stress at break, of 33, 17 and 9%, respectively, a substantial enhancement in wear resistance of 117% is observed.","The effect of chromic acid treatment on the mechanical and tribological properties of aramid fibre reinforced ultra-high molecular weight polyethylene composite Abs: Surface oxidation of ultra-high molecular weight polyethylene (UHMWPE) powder has an influence on the mixing procedure of chopped fibres and UHMWPE powder. Due to this oxidation hydrogen bonds can be formed between the fibres and powder particles, leading to a more homogeneous fibre-powder mixture. This treatment improves the fibre-matrix interface and thus the physical properties of the composite. Chromic acid treatment also has an influence on the mechanical and tribological properties of the aramid-UHMWPE composite. Although only a relatively small improvement is observed in the modulus, yield stress and stress at break, of 33, 17 and 9%, respectively, a substantial enhancement in wear resistance of 117% is observed."
1230909,Sabty-Daily et al. 2005,Size distribution and speciation of chromium in paint spray aerosol at an aerospace facility,"Spray painters are potentially exposed to aerosol containing Cr(VI) via inhalation of chromate-based paint spray. Two field studies were conducted at an aerospace facility to determine the size distribution and speciation of Cr(VI) in paint spray aerosol. Sampled paint products consisted of sparingly soluble strontium chromate in an epoxy resin matrix, a matrix generally known for its durability and toughness. Personal aerosol samples were collected using Sierra Marple personal cascade impactors and analyzed for Cr(VI) and total Cr. The size distribution of total Cr particles in the paint aerosol had a Mass Median Aerodynamic Diameter (MMAD) of 7.5 mum [Geometric Standard Deviation (GSD = 2.7 mum)] in both field studies. The MMAD of Cr(VI) particles was 8.5 mum (GSD = 2.2 mum). Particles &gt;2 mum constituted 90% or more of the total Cr and the Cr(VI) mass, in all sampled paint aerosols and were lognormally distributed. The target site for respiratory deposition of Cr in the aerosol was estimated based on the mass distribution of Cr according to particle size. On an average, 62% of the Cr and Cr(VI) mass in the paint aerosol consisted of particles &gt;10 mum. This study showed that 71.8% of Cr(VI) mass in paint spray aerosol potentially inhaled by a spray painter may deposit in the head airways region. Only 2.0 and 1.4% of Cr(VI) mass in the paint aerosol may potentially deposit in the alveolar and tracheobronchial region, respectively. The ratio of Cr(VI) mass to total Cr mass was determined in bulk paint and the data indicate that Cr was predominantly in the Cr(VI) valence state, before spraying. The ratio of Cr(VI) mass to total Cr mass was also determined in paint aerosol samples. The data indicated that there was a reduction of Cr(VI) regardless of Cr aerosol particle size. Cr(VI) reduction occurred most likely during the 8 h sample collection time period. These findings are in agreement with the findings that observed Cr(VI) reduction during collection of airborne Cr(VI) in samples of chromic acid mist. The use of Cr(VI) stabilizing sampling media and the storage of samples at lower temperatures (4 degrees C ) during and after sampling may avoid the underestimation of Cr(VI).","Size distribution and speciation of chromium in paint spray aerosol at an aerospace facility Abs: Spray painters are potentially exposed to aerosol containing Cr(VI) via inhalation of chromate-based paint spray. Two field studies were conducted at an aerospace facility to determine the size distribution and speciation of Cr(VI) in paint spray aerosol. Sampled paint products consisted of sparingly soluble strontium chromate in an epoxy resin matrix, a matrix generally known for its durability and toughness. Personal aerosol samples were collected using Sierra Marple personal cascade impactors and analyzed for Cr(VI) and total Cr. The size distribution of total Cr particles in the paint aerosol had a Mass Median Aerodynamic Diameter (MMAD) of 7.5 mum [Geometric Standard Deviation (GSD = 2.7 mum)] in both field studies. The MMAD of Cr(VI) particles was 8.5 mum (GSD = 2.2 mum). Particles &gt;2 mum constituted 90% or more of the total Cr and the Cr(VI) mass, in all sampled paint aerosols and were lognormally distributed. The target site for respiratory deposition of Cr in the aerosol was estimated based on the mass distribution of Cr according to particle size. On an average, 62% of the Cr and Cr(VI) mass in the paint aerosol consisted of particles &gt;10 mum. This study showed that 71.8% of Cr(VI) mass in paint spray aerosol potentially inhaled by a spray painter may deposit in the head airways region. Only 2.0 and 1.4% of Cr(VI) mass in the paint aerosol may potentially deposit in the alveolar and tracheobronchial region, respectively. The ratio of Cr(VI) mass to total Cr mass was determined in bulk paint and the data indicate that Cr was predominantly in the Cr(VI) valence state, before spraying. The ratio of Cr(VI) mass to total Cr mass was also determined in paint aerosol samples. The data indicated that there was a reduction of Cr(VI) regardless of Cr aerosol particle size. Cr(VI) reduction occurred most likely during the 8 h sample collection time period. These findings are in agreement with the findings that observed Cr(VI) reduction during collection of airborne Cr(VI) in samples of chromic acid mist. The use of Cr(VI) stabilizing sampling media and the storage of samples at lower temperatures (4 degrees C ) during and after sampling may avoid the underestimation of Cr(VI)."
1230908,Soylu 2004,Ultrastructural characterisation of the host-pathogen interface in white blister-infected Arabidopsis leaves,"In this study transmission electron microscopy (TEM) was used to examine details of the host-pathogen interface in Arabidopsis thaliana cotyledons infected by Albugo candida, causal agent of white blister. After successful entry through stomatal pores, the pathogen developed a substomatal vesicle and subsequently produced intercellular hyphae. TEM observations revealed that coenocytic intercellular hyphae ramified and spread intercellularly throughout the host tissue forming several haustoria in host mesophyll cells. Intracellular haustoria were spherical and 4.5 microm in diameter. Each haustorium was connected to intercellular hyphae by a narrow, slender haustorium neck. The cytoplasm of the haustorium included the organelles characteristic of the pathogen. No obvious response was observed in host cells following formation of haustoria. Most of the mesophyll cells contained normal haustoria and the host cytoplasm displayed a high degree of structural integrity. Absence of host cell wall alteration and cell death in penetrated host cells suggest that the pathogen exerts considerable control over basic cellular processes and in this respect, response to this biotrophic Oomycete differs considerably from responses to other pathogens such as necrotrophs. Modification of the host plasma membrane (PM) along the cell wall and around the haustoria, was detected by applying the periodic acid-chromic acid-phosphotungstic acid (PACP) staining technique. After staining with PACP, the host PM was found to be intensely electron dense where it was adjacent to the host cell wall and the distal region of the haustorial neck. By contrast, the extrahaustorial membrane, where the host PM surrounded the haustorium, was consistently very lightly stained.","Ultrastructural characterisation of the host-pathogen interface in white blister-infected Arabidopsis leaves Abs: In this study transmission electron microscopy (TEM) was used to examine details of the host-pathogen interface in Arabidopsis thaliana cotyledons infected by Albugo candida, causal agent of white blister. After successful entry through stomatal pores, the pathogen developed a substomatal vesicle and subsequently produced intercellular hyphae. TEM observations revealed that coenocytic intercellular hyphae ramified and spread intercellularly throughout the host tissue forming several haustoria in host mesophyll cells. Intracellular haustoria were spherical and 4.5 microm in diameter. Each haustorium was connected to intercellular hyphae by a narrow, slender haustorium neck. The cytoplasm of the haustorium included the organelles characteristic of the pathogen. No obvious response was observed in host cells following formation of haustoria. Most of the mesophyll cells contained normal haustoria and the host cytoplasm displayed a high degree of structural integrity. Absence of host cell wall alteration and cell death in penetrated host cells suggest that the pathogen exerts considerable control over basic cellular processes and in this respect, response to this biotrophic Oomycete differs considerably from responses to other pathogens such as necrotrophs. Modification of the host plasma membrane (PM) along the cell wall and around the haustoria, was detected by applying the periodic acid-chromic acid-phosphotungstic acid (PACP) staining technique. After staining with PACP, the host PM was found to be intensely electron dense where it was adjacent to the host cell wall and the distal region of the haustorial neck. By contrast, the extrahaustorial membrane, where the host PM surrounded the haustorium, was consistently very lightly stained."
1230907,Cho and  Park 2005,Effect of coexisting compounds on the sorption and reduction of trichloroethylene with iron,"Batch experiments were performed to study the effect of coexisting compounds on trichloroethylene (TCE) dechlorination and sorption in the presence of iron. Competitive sorption of TCE was observed with naphthalene as a coexisting contaminant, but the TCE reduction rate slightly increased with naphthalene, which is hardly subject to reduction. With carbon tetrachloride, nitrate, and chromate as reducible cocontaminants, the competitive reduction of TCE was observed in binary-contaminant systems. The reduction rate constant of TCE by iron filings decreased 1.5 times with carbon tetrachloride because of the competition for electrons. The TCE reduction rate with nitrate decreased five times because of the competition for electrons and the enhanced passivation. The sorbed mass of TCE on iron surface with chromate increased more than that without chromate because of the formation of (Cr, Fe)(OH)3 precipitations.","Effect of coexisting compounds on the sorption and reduction of trichloroethylene with iron Abs: Batch experiments were performed to study the effect of coexisting compounds on trichloroethylene (TCE) dechlorination and sorption in the presence of iron. Competitive sorption of TCE was observed with naphthalene as a coexisting contaminant, but the TCE reduction rate slightly increased with naphthalene, which is hardly subject to reduction. With carbon tetrachloride, nitrate, and chromate as reducible cocontaminants, the competitive reduction of TCE was observed in binary-contaminant systems. The reduction rate constant of TCE by iron filings decreased 1.5 times with carbon tetrachloride because of the competition for electrons. The TCE reduction rate with nitrate decreased five times because of the competition for electrons and the enhanced passivation. The sorbed mass of TCE on iron surface with chromate increased more than that without chromate because of the formation of (Cr, Fe)(OH)3 precipitations."
1230905,Singer Pressman and  Aldstadt Iii 2005,A remote in situ monitor based on continuous flow analysis for the quantitation of sub-micromolar levels of hexavalent chromium in natural waters,"We describe the design, optimization, and application of a small, lightweight, deployable monitoring instrument for accurately measuring parts-per-billion levels of hexavalent Cr in surface waters at hourly intervals. The monitor quantifies Cr(vi) using a standard molecular absorbance spectroscopic method, i.e. by formation of a complex with 1,5-diphenylcarbazide (DPC). The continuous flow analysis (CFA) design uses narrow conduits (0.90 mm) that are hot-forged onto poly(methyl methacrylate) ('Plexiglas') plates based on the method of Jannasch et al.(Anal. Chem., 1994, 66, 3352). The sample stream is drawn through the manifold at 25 microl min(-1) using a mini-peristaltic pump; osmotic pumps (10 microl h(-1)) are used to continuously inject reagent (2.0 mM DPC, 0.60 M HNO(3), 5.0% w/v acetone, and 0.10% w/v Brij-35) and to periodically introduce quality control standards and a cleaning solution (0.50 M HNO(3)). The 'Z-type' optical cell uses a liquid-core waveguide (10 mm) to collimate the light-emitting diode source beam (lambda(max) 574 nm) to a broadband photodiode detector. Figures of merit are: 7 min cycle time, response within 28 min and clear-down within 31 min, low waste generation (&lt;40 ml d(-1)), detection limit (3sigma) of 48.4 microg l(-1) as Cr(vi) or 0.411 microM as chromic acid, 1.54% relative standard deviation at 100 microg l(-1), and selectivity for dissolved Cr(vi) in authentic surface water samples containing moderate levels (&gt;0.21% w/v) of total particulate matter. Using a test chamber containing Milwaukee Harbor water that was periodically fortified with Cr(vi) standards, continuous testing over a 15 day period (354 h) yielded results that were in excellent agreement (&lt;5% variation) with measurements made using an ICP-MS reference method. Drift in the calibration model over the test period was 1.23% and the variation in a 0.50 mg l(-1) Cr(vi) standard was 3.8%(n= 11). Known interferences to the DPC chemistry (Mo, V, and Hg at &gt;5 mg l(-1)) were undetected in the harbor water by ICP-MS.","A remote in situ monitor based on continuous flow analysis for the quantitation of sub-micromolar levels of hexavalent chromium in natural waters Abs: We describe the design, optimization, and application of a small, lightweight, deployable monitoring instrument for accurately measuring parts-per-billion levels of hexavalent Cr in surface waters at hourly intervals. The monitor quantifies Cr(vi) using a standard molecular absorbance spectroscopic method, i.e. by formation of a complex with 1,5-diphenylcarbazide (DPC). The continuous flow analysis (CFA) design uses narrow conduits (0.90 mm) that are hot-forged onto poly(methyl methacrylate) ('Plexiglas') plates based on the method of Jannasch et al.(Anal. Chem., 1994, 66, 3352). The sample stream is drawn through the manifold at 25 microl min(-1) using a mini-peristaltic pump; osmotic pumps (10 microl h(-1)) are used to continuously inject reagent (2.0 mM DPC, 0.60 M HNO(3), 5.0% w/v acetone, and 0.10% w/v Brij-35) and to periodically introduce quality control standards and a cleaning solution (0.50 M HNO(3)). The 'Z-type' optical cell uses a liquid-core waveguide (10 mm) to collimate the light-emitting diode source beam (lambda(max) 574 nm) to a broadband photodiode detector. Figures of merit are: 7 min cycle time, response within 28 min and clear-down within 31 min, low waste generation (&lt;40 ml d(-1)), detection limit (3sigma) of 48.4 microg l(-1) as Cr(vi) or 0.411 microM as chromic acid, 1.54% relative standard deviation at 100 microg l(-1), and selectivity for dissolved Cr(vi) in authentic surface water samples containing moderate levels (&gt;0.21% w/v) of total particulate matter. Using a test chamber containing Milwaukee Harbor water that was periodically fortified with Cr(vi) standards, continuous testing over a 15 day period (354 h) yielded results that were in excellent agreement (&lt;5% variation) with measurements made using an ICP-MS reference method. Drift in the calibration model over the test period was 1.23% and the variation in a 0.50 mg l(-1) Cr(vi) standard was 3.8%(n= 11). Known interferences to the DPC chemistry (Mo, V, and Hg at &gt;5 mg l(-1)) were undetected in the harbor water by ICP-MS."
1230904,Acharya et al. 2006,Testicular dysfunction and antioxidative defense system of Swiss mice after chromic acid exposure,"Chromic acid (CrO(3)), a hexavalent compound of chromium (Cr) that is widely used in different industries, has been associated with reproductive abnormalities in male Swiss mice. The mechanism of male reproductive toxicity is not clear. Metal-induced reactive oxygen species (ROS) may impair spermatogenesis or alter sperm morphology. Therefore, in the present study we investigated the induction of oxidative stress in the testes of mice over time (5th-8th weeks) after a single intraperitoneal dose (1mg/kg body weight) of CrO(3). Exposed animals showed significantly decreased sperm counts and markedly increased rates of sperm abnormality. Oxidative stress was measured in terms of malondialdehyde content, the activities of superoxide dismutase, peroxidase, and catalase, and non-enzymatic antioxidants such as ascorbic acid. The significant changes in exposed groups relative to controls suggest that CrO(3) exposure suppressed antioxidant enzymes and ascorbic acid with a concomitant increase in the level of lipid peroxidation and H(2)O(2) to adversely affect testicular function.","Testicular dysfunction and antioxidative defense system of Swiss mice after chromic acid exposure Abs: Chromic acid (CrO(3)), a hexavalent compound of chromium (Cr) that is widely used in different industries, has been associated with reproductive abnormalities in male Swiss mice. The mechanism of male reproductive toxicity is not clear. Metal-induced reactive oxygen species (ROS) may impair spermatogenesis or alter sperm morphology. Therefore, in the present study we investigated the induction of oxidative stress in the testes of mice over time (5th-8th weeks) after a single intraperitoneal dose (1mg/kg body weight) of CrO(3). Exposed animals showed significantly decreased sperm counts and markedly increased rates of sperm abnormality. Oxidative stress was measured in terms of malondialdehyde content, the activities of superoxide dismutase, peroxidase, and catalase, and non-enzymatic antioxidants such as ascorbic acid. The significant changes in exposed groups relative to controls suggest that CrO(3) exposure suppressed antioxidant enzymes and ascorbic acid with a concomitant increase in the level of lipid peroxidation and H(2)O(2) to adversely affect testicular function."
1230903,Patel and  Mishra 2006,"Oxidation of cholesterol by a biomimetic oxidant, cetyltrimethylammonium dichromate","The oxidation of cholesterol by cetyltrimethylammonium dichromate (CTADC) in dichloromethane (DCM) yielded 7-dehydrocholesterol, while with addition of acetic acid in DCM the product was found to be 5-cholesten-3-one. The kinetics of oxidation of cholesterol by CTADC in DCM, in the presence of acid, was investigated with change in [acid], [cholesterol], [CTADC], [surfactant], temperature, and solvents. The reaction was found to be first order with acetic acid and fractional order with CTADC and cholesterol. Michaelis-Menten-type kinetics was observed with respect to cholesterol. The solvent isotope effect was found to be k(D2O)/k(H2O) = 0.72. The observed experimental data suggest that the reaction occurs in reversed micellar system, akin to an enzymatic environment, and the reaction path involves the intermediate formation of an ester complex, which undergoes decomposition to give the product.","Oxidation of cholesterol by a biomimetic oxidant, cetyltrimethylammonium dichromate Abs: The oxidation of cholesterol by cetyltrimethylammonium dichromate (CTADC) in dichloromethane (DCM) yielded 7-dehydrocholesterol, while with addition of acetic acid in DCM the product was found to be 5-cholesten-3-one. The kinetics of oxidation of cholesterol by CTADC in DCM, in the presence of acid, was investigated with change in [acid], [cholesterol], [CTADC], [surfactant], temperature, and solvents. The reaction was found to be first order with acetic acid and fractional order with CTADC and cholesterol. Michaelis-Menten-type kinetics was observed with respect to cholesterol. The solvent isotope effect was found to be k(D2O)/k(H2O) = 0.72. The observed experimental data suggest that the reaction occurs in reversed micellar system, akin to an enzymatic environment, and the reaction path involves the intermediate formation of an ester complex, which undergoes decomposition to give the product."
1230902,Cao et al. 2006,Glow discharge plasma treatment of polyethylene tubing with tetraglyme results in ultralow fibrinogen adsorption and greatly reduced platelet adhesion,"Previous studies from our lab have shown that fibrinogen adsorption (Gamma(Fg)) must be reduced below 10 ng/cm(2) to significantly reduce platelet adhesion, and that radio frequency glow discharge (RFGD) treatment of polymeric films in the presence of tetraethylene glycol dimethyl ether (tetraglyme) can reduce Gamma(Fg) to the desired ultralow value. In this report, the effects of RFGD coatings of tetraglyme on the lumenal surface of PE tubing on Gamma(Fg) and on blood interactions both in vitro and ex vivo are described. Gamma(Fg) on the tetraglyme-coated PE tubing was reduced to the desired ultralow level (&lt;10 ng/cm(2)), and we also observed a significant decrease in adsorption of von Willebrand's factor. In vitro platelet adhesion from washed platelet suspensions, platelet rich plasma, or whole blood to tetraglyme-coated PE tubing was decreased compared to PE, polyurethane, or silicone rubber tubes. In addition, thrombin generation by platelets adherent to tetraglyme-coated PE was also much less than by platelets adherent to PE. When inserted in an ex vivo carotid artery-carotid artery shunt in sheep, the RFGD tetraglyme-coated PE exhibited a very low number of adherent platelets compared to heparin-coated, chromic acid-etched, or plain PE. The RFGD tetraglyme-coated PE tubes exhibited high protein and platelet resistance in vitro, and high platelet resistance ex vivo. The improved hemocompatibility is attributed to the unique chemical structure of RFGD tetraglyme that makes it highly protein resistant.","Glow discharge plasma treatment of polyethylene tubing with tetraglyme results in ultralow fibrinogen adsorption and greatly reduced platelet adhesion Abs: Previous studies from our lab have shown that fibrinogen adsorption (Gamma(Fg)) must be reduced below 10 ng/cm(2) to significantly reduce platelet adhesion, and that radio frequency glow discharge (RFGD) treatment of polymeric films in the presence of tetraethylene glycol dimethyl ether (tetraglyme) can reduce Gamma(Fg) to the desired ultralow value. In this report, the effects of RFGD coatings of tetraglyme on the lumenal surface of PE tubing on Gamma(Fg) and on blood interactions both in vitro and ex vivo are described. Gamma(Fg) on the tetraglyme-coated PE tubing was reduced to the desired ultralow level (&lt;10 ng/cm(2)), and we also observed a significant decrease in adsorption of von Willebrand's factor. In vitro platelet adhesion from washed platelet suspensions, platelet rich plasma, or whole blood to tetraglyme-coated PE tubing was decreased compared to PE, polyurethane, or silicone rubber tubes. In addition, thrombin generation by platelets adherent to tetraglyme-coated PE was also much less than by platelets adherent to PE. When inserted in an ex vivo carotid artery-carotid artery shunt in sheep, the RFGD tetraglyme-coated PE exhibited a very low number of adherent platelets compared to heparin-coated, chromic acid-etched, or plain PE. The RFGD tetraglyme-coated PE tubes exhibited high protein and platelet resistance in vitro, and high platelet resistance ex vivo. The improved hemocompatibility is attributed to the unique chemical structure of RFGD tetraglyme that makes it highly protein resistant."
1230899,Dülgergil et al. 2007,An industrial dental-erosion by chromic Acid: a case report,"A case of uncommon occupational dental erosion was reported in an individual who had worked in the war industry for twenty years. This occupation involved daily, at least 8 hours, inhalation of chromic acid being used for cleaning of barrel of cannons. The erosion manifested as dental sensitivity with excessive cervical erosion even with pulpal exposure in certain teeth. Moreover, due to the adverse effect of the chemical against to gingival and/or periodontal tissues, the lesions were extremely harmful with respect to the exposed root-cementum. After proper periodontal therapy, cervical lesions were treated conservatively with a compomer based restorative material without cavity preparation. Although today it is not common due to the well-controlled working conditions, occupational combined dental and medical problems via airborne fumes and/or elements can be seen at workers in chemical factories. A cumulative biohazardous effect is generally seen as not only medical but also dental disorders.","An industrial dental-erosion by chromic Acid: a case report Abs: A case of uncommon occupational dental erosion was reported in an individual who had worked in the war industry for twenty years. This occupation involved daily, at least 8 hours, inhalation of chromic acid being used for cleaning of barrel of cannons. The erosion manifested as dental sensitivity with excessive cervical erosion even with pulpal exposure in certain teeth. Moreover, due to the adverse effect of the chemical against to gingival and/or periodontal tissues, the lesions were extremely harmful with respect to the exposed root-cementum. After proper periodontal therapy, cervical lesions were treated conservatively with a compomer based restorative material without cavity preparation. Although today it is not common due to the well-controlled working conditions, occupational combined dental and medical problems via airborne fumes and/or elements can be seen at workers in chemical factories. A cumulative biohazardous effect is generally seen as not only medical but also dental disorders."
1230897,Dong et al. 2007,Jones oxidation and high performance liquid chromatographic analysis of cholesterol in biological samples,"A simple pre-column derivatization procedure for HPLC analysis of cholesterol in biological samples was developed. Cholesterol was treated with chromic acid and sulfuric acid in acetone (the Jones oxidation) and cholest-4-en-3,6-dione was formed. The reaction was finished in 5 min at room temperature and the product showed a strong UV absorbance at 250 nm that enabled an HPLC detection limit of 0.2 pmol. With stigmasterol as an internal standard, the reaction was applied to the analysis of total and free cholesterol in serum and high-density lipoproteins and the analysis showed a within-run and total coefficient of variation of about 0.2% and 0.5%, respectively.","Jones oxidation and high performance liquid chromatographic analysis of cholesterol in biological samples Abs: A simple pre-column derivatization procedure for HPLC analysis of cholesterol in biological samples was developed. Cholesterol was treated with chromic acid and sulfuric acid in acetone (the Jones oxidation) and cholest-4-en-3,6-dione was formed. The reaction was finished in 5 min at room temperature and the product showed a strong UV absorbance at 250 nm that enabled an HPLC detection limit of 0.2 pmol. With stigmasterol as an internal standard, the reaction was applied to the analysis of total and free cholesterol in serum and high-density lipoproteins and the analysis showed a within-run and total coefficient of variation of about 0.2% and 0.5%, respectively."
1230896,Ogawa et al. 2007,Four cases of chemical burns thought to be caused by exposure to chromic acid mist,,Four cases of chemical burns thought to be caused by exposure to chromic acid mist Abs: 
1230895,Robinett et al. 2010,Special considerations in hazardous materials burns,"Those practicing Emergency Medicine are frequently faced with a patient presenting with a chemical burn. Most dermal chemical burns are minor and do not require specialized treatment. Occasionally, however, the clinician may be in the position of responding to a chemical burn in which standard therapy of irrigation and good wound care may not be sufficient or, at worst, contraindicated. Several burn conditions will be reviewed, some of those requiring only specific decontamination techniques, as in hot tar, others posing special hazards to clinicians, as in elemental metals, and finally, examples are given of hazardous materials requiring attention to systemic effects, as in hydrofluoric acid.","Special considerations in hazardous materials burns Abs: Those practicing Emergency Medicine are frequently faced with a patient presenting with a chemical burn. Most dermal chemical burns are minor and do not require specialized treatment. Occasionally, however, the clinician may be in the position of responding to a chemical burn in which standard therapy of irrigation and good wound care may not be sufficient or, at worst, contraindicated. Several burn conditions will be reviewed, some of those requiring only specific decontamination techniques, as in hot tar, others posing special hazards to clinicians, as in elemental metals, and finally, examples are given of hazardous materials requiring attention to systemic effects, as in hydrofluoric acid."
1230894,Ishida et al. 2008,Comparison of preparation methods for the evaluation of nerve axons,"We have conducted a study to compare various preparation methods, including a certain number of new methods, to find which ones are best suited to the morphological evaluation of nerve fibers in the pyramidal tract of the human medulla oblongata. Our main concern was to find fixation and staining methods that would minimize errors, especially regarding the tissue shrinkage ratio and the ease of staining. From the two fixation methods we examined, the most satisfactory was the secondary chromic acid fixation (which gave the best overall results when followed by nitrocellulose embedding), as it gives the lowest shrinkage ratio with the narrowest range (10 +/- 0%). Among the ten staining methods we tested, we found that the most suitable for morphological evaluation were the discriminative staining methods (Luxol fast blue-Periodic acid-Schiff-Hematoxylin stain, Masson-Goldner-Goto method and modified Hematoxylin-Eosin stain) and the silver impregnation methods (Luxol fast blue-Silver impregnation and Luxol fast blue-Silver impregnation-Periodic acid-Schiff-Hematoxylin).","Comparison of preparation methods for the evaluation of nerve axons Abs: We have conducted a study to compare various preparation methods, including a certain number of new methods, to find which ones are best suited to the morphological evaluation of nerve fibers in the pyramidal tract of the human medulla oblongata. Our main concern was to find fixation and staining methods that would minimize errors, especially regarding the tissue shrinkage ratio and the ease of staining. From the two fixation methods we examined, the most satisfactory was the secondary chromic acid fixation (which gave the best overall results when followed by nitrocellulose embedding), as it gives the lowest shrinkage ratio with the narrowest range (10 +/- 0%). Among the ten staining methods we tested, we found that the most suitable for morphological evaluation were the discriminative staining methods (Luxol fast blue-Periodic acid-Schiff-Hematoxylin stain, Masson-Goldner-Goto method and modified Hematoxylin-Eosin stain) and the silver impregnation methods (Luxol fast blue-Silver impregnation and Luxol fast blue-Silver impregnation-Periodic acid-Schiff-Hematoxylin)."
1230893,Islam and  Das 2008,"Heteroaromatic N-base ligands in 1,10-phenanthroline- and 2,2'-bipyridyl-assisted chromic acid oxidation of (-)-L-sorbose in aqueous micellar acid media: a kinetic study","In aqueous sulfuric acid media, Cr(VI) oxidation of (-)-L-sorbose in the presence and absence of catalysts like 1,10-phenanthroline (phen), 2,2'-bipyridyl (bipy) have been carried out under the conditions, [(-)-L-sorbose](T)&gt;[Cr(VI)](T) at different temperatures. Under the experimental conditions, the monomeric species of Cr(VI) has been found kinetically active in the absence of phen and bipy catalysts, while in the heteroaromatic N-base catalysed path, the Cr(VI)-phen and Cr(VI)-bipy complexes have been suggested as the active oxidants. In the catalysed path, Cr(VI)-L complex (L=phen, bipy) receives a nucleophilic attack by the substrate to form a ternary complex which subsequently experiences a redox decomposition through two-electron transfer leading to the organic products and a Cr(IV)-L complex. Both the uncatalysed and catalysed paths show first-order dependence on [(-)-L-sorbose](T) and [Cr(VI)](T). The uncatalysed path shows second-order in [H(+)], while the catalysed path shows a first-order dependence on [H(+)]. The heteroaromatic N-base catalysed path is first-order in [phen](T) or [bipy](T). These findings remain unchanged in the presence of externally added surfactants. The cationic surfactant (i.e., N-cetylpyridinium chloride (CPC)) inhibits the rate in both the catalysed and uncatalysed paths, whereas the anionic surfactant (i.e., sodium dodecyl sulfate (SDS)) shows the rate accelerating effect for both the uncatalysed and catalysed paths. The observed micellar effects have been rationalised by considering the distribution of the reactants between the micellar and aqueous phases in terms of the proposed reaction mechanism.","Heteroaromatic N-base ligands in 1,10-phenanthroline- and 2,2'-bipyridyl-assisted chromic acid oxidation of (-)-L-sorbose in aqueous micellar acid media: a kinetic study Abs: In aqueous sulfuric acid media, Cr(VI) oxidation of (-)-L-sorbose in the presence and absence of catalysts like 1,10-phenanthroline (phen), 2,2'-bipyridyl (bipy) have been carried out under the conditions, [(-)-L-sorbose](T)&gt;[Cr(VI)](T) at different temperatures. Under the experimental conditions, the monomeric species of Cr(VI) has been found kinetically active in the absence of phen and bipy catalysts, while in the heteroaromatic N-base catalysed path, the Cr(VI)-phen and Cr(VI)-bipy complexes have been suggested as the active oxidants. In the catalysed path, Cr(VI)-L complex (L=phen, bipy) receives a nucleophilic attack by the substrate to form a ternary complex which subsequently experiences a redox decomposition through two-electron transfer leading to the organic products and a Cr(IV)-L complex. Both the uncatalysed and catalysed paths show first-order dependence on [(-)-L-sorbose](T) and [Cr(VI)](T). The uncatalysed path shows second-order in [H(+)], while the catalysed path shows a first-order dependence on [H(+)]. The heteroaromatic N-base catalysed path is first-order in [phen](T) or [bipy](T). These findings remain unchanged in the presence of externally added surfactants. The cationic surfactant (i.e., N-cetylpyridinium chloride (CPC)) inhibits the rate in both the catalysed and uncatalysed paths, whereas the anionic surfactant (i.e., sodium dodecyl sulfate (SDS)) shows the rate accelerating effect for both the uncatalysed and catalysed paths. The observed micellar effects have been rationalised by considering the distribution of the reactants between the micellar and aqueous phases in terms of the proposed reaction mechanism."
1230892,Zhao et al. 2008,[A case of acute chromic acid poisoning],,[A case of acute chromic acid poisoning] Abs: 
1230890,Souma et al. 2008,Morphological evaluation of the human pyramidal tract: gender and age differences,"Using a preparation method composed of secondary chromic acid fixation, nitrocellulose embedding and Luxol fast blue-PAS-hematoxylin stain (a discriminative staining method) for the purpose of axonal discrimination, we examined 43 human spinal cords (31 males and 12 females) at the C5 level to find the differences due to gender and aging in axons of the lateral corticospinal tract. These results can be of great help in understanding the motor functions in relation to gender differences and the aging process.","Morphological evaluation of the human pyramidal tract: gender and age differences Abs: Using a preparation method composed of secondary chromic acid fixation, nitrocellulose embedding and Luxol fast blue-PAS-hematoxylin stain (a discriminative staining method) for the purpose of axonal discrimination, we examined 43 human spinal cords (31 males and 12 females) at the C5 level to find the differences due to gender and aging in axons of the lateral corticospinal tract. These results can be of great help in understanding the motor functions in relation to gender differences and the aging process."
1230889,Baresic et al. 2009,Survival after severe acute chromic acid poisoning complicated with renal and liver failure,"Chromic acid is a strong metal acid and acute poisoning is very rare, but very serious with severe skin injury, renal and liver failure. The majority of published cases were suicide attempts with lethal outcomes. We describe the case of a 55-year-old man who had accidentally taken a sip of 20% chromic acid (estimated chromium intake: 2.3 g). Renal and liver failure were not present at presentation, but appeared later in the course of disease. He was treated with hemodialysis, no chelating agents or other methods for enhancing elimination were used. Liver and renal function improved over the next 30 days and the patient was discharged after 45 days of hospitalization with no need for dialysis. In the follow-up period of eight months his renal function remained depressed, but stable.","Survival after severe acute chromic acid poisoning complicated with renal and liver failure Abs: Chromic acid is a strong metal acid and acute poisoning is very rare, but very serious with severe skin injury, renal and liver failure. The majority of published cases were suicide attempts with lethal outcomes. We describe the case of a 55-year-old man who had accidentally taken a sip of 20% chromic acid (estimated chromium intake: 2.3 g). Renal and liver failure were not present at presentation, but appeared later in the course of disease. He was treated with hemodialysis, no chelating agents or other methods for enhancing elimination were used. Liver and renal function improved over the next 30 days and the patient was discharged after 45 days of hospitalization with no need for dialysis. In the follow-up period of eight months his renal function remained depressed, but stable."
1230887,Bai and  Achilefu 2011,Synthesis and spectroscopy of near infrared fluorescent dyes for investigating dichromic fluorescence,"We developed a series of near infrared (NIR) cyanine dyes to study dichromic fluorescence phenomenon, which provides new protocols for in vivo optical imaging. Preliminary spectroscopic studies show that dichromic fluorescence correlates with structural symmetry. This feature suggests the potential use of dichromic fluorescent molecules to study biological processes that can alter the structural symmetry of the molecular probes.","Synthesis and spectroscopy of near infrared fluorescent dyes for investigating dichromic fluorescence Abs: We developed a series of near infrared (NIR) cyanine dyes to study dichromic fluorescence phenomenon, which provides new protocols for in vivo optical imaging. Preliminary spectroscopic studies show that dichromic fluorescence correlates with structural symmetry. This feature suggests the potential use of dichromic fluorescent molecules to study biological processes that can alter the structural symmetry of the molecular probes."
1230886,Zhou et al. 2011,Serum cholesterol measured by isotope dilution liquid chromatography tandem mass spectrometry,"<strong>BACKGROUND: </strong>Accurate cholesterol measurements are essential for the prevention and management of cardiovascular diseases. Quality assurance of cholesterol measurements requires reference methods.<br /><br /><strong>METHODS: </strong>An isotope dilution liquid chromatography mass spectrometric (ID/LC/MS) method was developed. Serum samples were sampled volumetrically using automated dilutors, treated with potassium hydroxide and equilibrated with 3,4-(13)C(2) cholesterol. The natural cholesterol and the internal standard were extracted with hexane and oxidized to cholest-4-en-3,6-diones with chromic acid. The oxidation products were separated on reversed phase LC and detected by tandem MS. The method was calibrated using aqueous cholesterol calibrators and the calibration function was established with a polynomial regression.<br /><br /><strong>RESULTS: </strong>The correlation coefficients of the calibration curves were always &gt;0.9999. The coefficients of variation (CV) of the volumetric sampling and the LC/MS analysis averaged 0.22% and 0.50%, respectively, and the total measurement CV was 0.60%. Other sources of measurement uncertainty were minor. Results on certified reference materials agreed within 1% of the certified values.<br /><br /><strong>CONCLUSIONS: </strong>An ID/LC/MS method for serum cholesterol has been developed. The method is simple and accurate and may be used as a candidate reference method.","Serum cholesterol measured by isotope dilution liquid chromatography tandem mass spectrometry Abs: <strong>BACKGROUND: </strong>Accurate cholesterol measurements are essential for the prevention and management of cardiovascular diseases. Quality assurance of cholesterol measurements requires reference methods.<br /><br /><strong>METHODS: </strong>An isotope dilution liquid chromatography mass spectrometric (ID/LC/MS) method was developed. Serum samples were sampled volumetrically using automated dilutors, treated with potassium hydroxide and equilibrated with 3,4-(13)C(2) cholesterol. The natural cholesterol and the internal standard were extracted with hexane and oxidized to cholest-4-en-3,6-diones with chromic acid. The oxidation products were separated on reversed phase LC and detected by tandem MS. The method was calibrated using aqueous cholesterol calibrators and the calibration function was established with a polynomial regression.<br /><br /><strong>RESULTS: </strong>The correlation coefficients of the calibration curves were always &gt;0.9999. The coefficients of variation (CV) of the volumetric sampling and the LC/MS analysis averaged 0.22% and 0.50%, respectively, and the total measurement CV was 0.60%. Other sources of measurement uncertainty were minor. Results on certified reference materials agreed within 1% of the certified values.<br /><br /><strong>CONCLUSIONS: </strong>An ID/LC/MS method for serum cholesterol has been developed. The method is simple and accurate and may be used as a candidate reference method."
1230884,Huang et al. 2011,One-PCR-tube approach for in situ DNA isolation and detection,"Traditional real-time polymerase chain reaction (PCR) requires a purified DNA sample for PCR amplification and detection. This requires PCR tests be conducted in clean laboratories, and limits its applications for field tests. This work developed a method that can carry out DNA purification, amplification and detection in a single PCR tube. The polypropylene PCR tube was first treated with chromic acid and peptide nucleic acids (PNA) as DNA-capturer were immobilized on the internal surface of the tube. Cauliflower mosaic virus 35S (CaMV-35S) promoter in the crude extract was hybridized with the PNA on the tube surface, and the inhibitors, interfering agents and irrelevant DNA in the crude extract were effectively removed by rinsing with buffer solutions. The tube that has captured the target DNA can be used for the following real-time PCR (RT-PCR). By using this approach, the detection of less than 2500 copies of 35S plasmids in a complex sample could be completed within 3 hours. Chocolate samples were tested for real sample analysis, and 35S plasmids in genetically modified chocolate samples have been successfully identified with this method in situ. The novel One-PCR-tube method is competitive for commercial kits with the same time and simpler operation procedure. This method may be widely used for identifying food that contains modified DNA and specific pathogens in the field.","One-PCR-tube approach for in situ DNA isolation and detection Abs: Traditional real-time polymerase chain reaction (PCR) requires a purified DNA sample for PCR amplification and detection. This requires PCR tests be conducted in clean laboratories, and limits its applications for field tests. This work developed a method that can carry out DNA purification, amplification and detection in a single PCR tube. The polypropylene PCR tube was first treated with chromic acid and peptide nucleic acids (PNA) as DNA-capturer were immobilized on the internal surface of the tube. Cauliflower mosaic virus 35S (CaMV-35S) promoter in the crude extract was hybridized with the PNA on the tube surface, and the inhibitors, interfering agents and irrelevant DNA in the crude extract were effectively removed by rinsing with buffer solutions. The tube that has captured the target DNA can be used for the following real-time PCR (RT-PCR). By using this approach, the detection of less than 2500 copies of 35S plasmids in a complex sample could be completed within 3 hours. Chocolate samples were tested for real sample analysis, and 35S plasmids in genetically modified chocolate samples have been successfully identified with this method in situ. The novel One-PCR-tube method is competitive for commercial kits with the same time and simpler operation procedure. This method may be widely used for identifying food that contains modified DNA and specific pathogens in the field."
1230882,Lin et al. 2011,Preoxidation for colorimetric sensor array detection of VOCs,"A disposable preoxidation technique that dramatically improves the detection and identification of volatile organic compounds (VOCs) by a colorimetric sensor array is reported. Passing a vapor stream through a tube packed with chromic acid on silica immediately before the colorimetric sensor array substantially increases the sensitivity to less-reactive VOCs and improves the limits of detection (LODs) ~300-fold, permitting the detection, identification, and discrimination of 20 commonly found indoor VOC pollutants at both their immediately dangerous to life or health (IDLH) and permissible exposure limit (PEL) concentrations. The LODs of these pollutants were on average 1.4% of their respective PELs.","Preoxidation for colorimetric sensor array detection of VOCs Abs: A disposable preoxidation technique that dramatically improves the detection and identification of volatile organic compounds (VOCs) by a colorimetric sensor array is reported. Passing a vapor stream through a tube packed with chromic acid on silica immediately before the colorimetric sensor array substantially increases the sensitivity to less-reactive VOCs and improves the limits of detection (LODs) ~300-fold, permitting the detection, identification, and discrimination of 20 commonly found indoor VOC pollutants at both their immediately dangerous to life or health (IDLH) and permissible exposure limit (PEL) concentrations. The LODs of these pollutants were on average 1.4% of their respective PELs."
1230881,Xiang et al. 2011,Intensive chromic acid burns and acute chromium poisoning with acute renal failure,,Intensive chromic acid burns and acute chromium poisoning with acute renal failure Abs: 
1227793,Jo et al. 2008,Toxicity identification and reduction of wastewaters from a pigment manufacturing factory,"In this study, major toxicants in pigment wastewaters (i.e. raw wastewater and effluent) were determined by toxicity identification evaluations (TIEs), and changes in their toxicities due to combined gamma-ray (gamma-ray) and ozone treatments were evaluated. From TIE results using Daphnia magna, Cr(VI) and o-toluidine were identified as major toxicants in the raw wastewater with concentrations of 2.47 and 25.3mg l(-1), respectively. This was confirmed by subsequent spiking and mass balance approaches. For effluent, TIE results suggested that organic anions were likely responsible for the observed toxicities. Toxicity reduction tests showed that gamma-rays with ozone treatment after coagulation was more efficient in reducing toxicities in the raw wastewater (3.9-2.0 TU) than gamma-ray treatment alone (3.9-3.1 TU). For pigment effluent, gamma-ray/O3 treatment resulted in a complete removal of the acute toxicity.","Toxicity identification and reduction of wastewaters from a pigment manufacturing factory Abs: In this study, major toxicants in pigment wastewaters (i.e. raw wastewater and effluent) were determined by toxicity identification evaluations (TIEs), and changes in their toxicities due to combined gamma-ray (gamma-ray) and ozone treatments were evaluated. From TIE results using Daphnia magna, Cr(VI) and o-toluidine were identified as major toxicants in the raw wastewater with concentrations of 2.47 and 25.3mg l(-1), respectively. This was confirmed by subsequent spiking and mass balance approaches. For effluent, TIE results suggested that organic anions were likely responsible for the observed toxicities. Toxicity reduction tests showed that gamma-rays with ozone treatment after coagulation was more efficient in reducing toxicities in the raw wastewater (3.9-2.0 TU) than gamma-ray treatment alone (3.9-3.1 TU). For pigment effluent, gamma-ray/O3 treatment resulted in a complete removal of the acute toxicity."
1227466,Kiran et al. 2008,Speciation determination of chromium(III) and (VI) using preconcentration cloud point extraction with flame atomic absorption spectrometry (FAAS),"bis-[2-Hydroxy-1-naphthaldehyde] thiourea was synthesized and preconcentration cloud point extraction (CPE) for speciation determination of chromium(III) and (VI) in various environmental samples with flame atomic absorption spectrometry (FAAS) has been developed. Chromium(III) complexes with bis-[2-hydroxynaphthaldehyde] thiourea is subsequently entrapped in the surfactant micelles. After complexation of chromium(III) with reagent, the analyte was quantitatively extracted to the surfactant-rich phase in the non-ionic surfactant Triton X-100 after centrifugation. The effect of pH, concentration of chelating agent, surfactant, equilibration temperature and time on CPE was studied. The relative standard deviation was 2.13% and the limits of detection were around 0.18 microg L(-1).","Speciation determination of chromium(III) and (VI) using preconcentration cloud point extraction with flame atomic absorption spectrometry (FAAS) Abs: bis-[2-Hydroxy-1-naphthaldehyde] thiourea was synthesized and preconcentration cloud point extraction (CPE) for speciation determination of chromium(III) and (VI) in various environmental samples with flame atomic absorption spectrometry (FAAS) has been developed. Chromium(III) complexes with bis-[2-hydroxynaphthaldehyde] thiourea is subsequently entrapped in the surfactant micelles. After complexation of chromium(III) with reagent, the analyte was quantitatively extracted to the surfactant-rich phase in the non-ionic surfactant Triton X-100 after centrifugation. The effect of pH, concentration of chelating agent, surfactant, equilibration temperature and time on CPE was studied. The relative standard deviation was 2.13% and the limits of detection were around 0.18 microg L(-1)."
1225584,Suksabye et al. 2010,A reinvestigation of EXAFS and EPR spectroscopic measurements of chromium(VI) reduction by coir pith,"New measurements using extended X-ray absorption fine structure (EXAFS) and electron paramagnetic resonance (EPR) techniques are consistent with Cr in the Cr(III) oxidation state as the main product from the adsorption of Cr(VI) on coir pith. These confirm the previous X-ray measurements, but differ from the results of previous EPR studies, which indicated that Cr(V) was the main form of Cr. The reason for this discrepancy is the presence of a broad signal from Cr(III) in an unsymmetrical environment that was missed previously; the Cr(V) component is in fact only a minor reaction product. As a result of this problem with spectral acquisition and interpretation, some simple recommendations are presented for conducting EPR investigations on natural systems.","A reinvestigation of EXAFS and EPR spectroscopic measurements of chromium(VI) reduction by coir pith Abs: New measurements using extended X-ray absorption fine structure (EXAFS) and electron paramagnetic resonance (EPR) techniques are consistent with Cr in the Cr(III) oxidation state as the main product from the adsorption of Cr(VI) on coir pith. These confirm the previous X-ray measurements, but differ from the results of previous EPR studies, which indicated that Cr(V) was the main form of Cr. The reason for this discrepancy is the presence of a broad signal from Cr(III) in an unsymmetrical environment that was missed previously; the Cr(V) component is in fact only a minor reaction product. As a result of this problem with spectral acquisition and interpretation, some simple recommendations are presented for conducting EPR investigations on natural systems."
1223268,Barrera-Diaz et al. 2012,"A review of chemical, electrochemical and biological methods for aqueous Cr(VI) reduction","Hexavalent chromium is of particular environmental concern due to its toxicity and mobility and is challenging to remove from industrial wastewater. It is a strong oxidizing agent that is carcinogenic and mutagenic and diffuses quickly through soil and aquatic environments. It does not form insoluble compounds in aqueous solutions, so separation by precipitation is not feasible. While Cr(VI) oxyanions are very mobile and toxic in the environment, Cr(III) cations are not. Like many metal cations, Cr(III) forms insoluble precipitates. Thus, reducing Cr(VI) to Cr(III) simplifies its removal from effluent and also reduces its toxicity and mobility. In this review, we describe the environmental implications of Cr(VI) presence in aqueous solutions, the chemical species that could be present and then we describe the technologies available to efficiently reduce hexavalent chromium.","A review of chemical, electrochemical and biological methods for aqueous Cr(VI) reduction Abs: Hexavalent chromium is of particular environmental concern due to its toxicity and mobility and is challenging to remove from industrial wastewater. It is a strong oxidizing agent that is carcinogenic and mutagenic and diffuses quickly through soil and aquatic environments. It does not form insoluble compounds in aqueous solutions, so separation by precipitation is not feasible. While Cr(VI) oxyanions are very mobile and toxic in the environment, Cr(III) cations are not. Like many metal cations, Cr(III) forms insoluble precipitates. Thus, reducing Cr(VI) to Cr(III) simplifies its removal from effluent and also reduces its toxicity and mobility. In this review, we describe the environmental implications of Cr(VI) presence in aqueous solutions, the chemical species that could be present and then we describe the technologies available to efficiently reduce hexavalent chromium."
1222828,Cocco et al. 1996,Occupational risk factors for gastric cancer: an overview,BIOSIS COPYRIGHT: BIOL ABS. RRM LITERATURE REVIEW HUMAN OCCUPATIONAL HEALTH ONCOLOGY EPIDEMIOLOGY GASTRIC CANCER OCCUPATIONAL RISK FACTORS NITROSAMINES AGRICULTURAL CHEMICALS METALS IONIZING RADIATION ASBESTOS NITROGEN OXIDES POLYCYCLIC AROMATIC HYDROCARBONS DIGESTIVE SYSTEM DISEASE NEOPLASTIC DISEASE,Occupational risk factors for gastric cancer: an overview Abs: BIOSIS COPYRIGHT: BIOL ABS. RRM LITERATURE REVIEW HUMAN OCCUPATIONAL HEALTH ONCOLOGY EPIDEMIOLOGY GASTRIC CANCER OCCUPATIONAL RISK FACTORS NITROSAMINES AGRICULTURAL CHEMICALS METALS IONIZING RADIATION ASBESTOS NITROGEN OXIDES POLYCYCLIC AROMATIC HYDROCARBONS DIGESTIVE SYSTEM DISEASE NEOPLASTIC DISEASE
1222823,Basketter et al. 1994,The performance of the local lymph node assay with chemicals identified as contact allergens in the human maximization test,"For many years, tests in the guinea pig have been the favoured option for the identification of the skin sensitization potential of chemicals. However, the mouse has been used widely in immunology research and can represent a viable alternative. A variety of murine assays have been described, including several methods based on ear swelling as an endpoint. Another option is to assess induced lymph node cell proliferation and it is this which forms the basis of the murine local lymph node assay (LLNA). The LLNA has undergone several successful interlaboratory validations and compares well with standard guinea pig assays. In the present study, the performance of the LLNA was examined with chemicals tested previously in the human maximization test (HMT). 30 chemicals, 23 of which proved positive in the HMT and seven of which were negative, have been tested. All but four of the materials found positive in the HMT also tested positive in the LLNA. Of these four, sulfanilamide and paraben esters would not classify as skin sensitizers in the guinea pig maximization test and nickel has been found to yield variable results in a number of predictive animal tests. Of the seven substances which proved negative in the HMT, six were also negative in the LLNA, the exception being sodium dodecyl sulfate. These data demonstrate that the LLNA is able to identify accurately chemicals which have the potential to cause significant allergic contact dermatitis in humans.","The performance of the local lymph node assay with chemicals identified as contact allergens in the human maximization test Abs: For many years, tests in the guinea pig have been the favoured option for the identification of the skin sensitization potential of chemicals. However, the mouse has been used widely in immunology research and can represent a viable alternative. A variety of murine assays have been described, including several methods based on ear swelling as an endpoint. Another option is to assess induced lymph node cell proliferation and it is this which forms the basis of the murine local lymph node assay (LLNA). The LLNA has undergone several successful interlaboratory validations and compares well with standard guinea pig assays. In the present study, the performance of the LLNA was examined with chemicals tested previously in the human maximization test (HMT). 30 chemicals, 23 of which proved positive in the HMT and seven of which were negative, have been tested. All but four of the materials found positive in the HMT also tested positive in the LLNA. Of these four, sulfanilamide and paraben esters would not classify as skin sensitizers in the guinea pig maximization test and nickel has been found to yield variable results in a number of predictive animal tests. Of the seven substances which proved negative in the HMT, six were also negative in the LLNA, the exception being sodium dodecyl sulfate. These data demonstrate that the LLNA is able to identify accurately chemicals which have the potential to cause significant allergic contact dermatitis in humans."
1222795,Bosworth et al. 1987,A forward mutation assay using ampicillin-resistance in Escherichia coli designed for investigating the mutagenicity of biological samples,"The development of a bacterial mutation assay using forward mutation to ampicillin-resistance is described. It is a technically simple assay using Escherichia coli D494uvrB transformed with a multi-copy mutator plasmid pGW1700. Mutation is detected by an increase in the frequency of ampicillin-resistant colonies following treatment of bacteria with the test material during logarithmic growth. The determination of viable counts allows a correction factor to be applied to compensate for the effects of sample-induced growth enhancement or toxicity on the bacterial population. The assay has been tested with a range of reference mutagens. It is particularly sensitive to base-pair substitution mutagens, detecting these at doses equal to or less than those detected in the Salmonella/microsome assay or the SOS Chromotest. The assay also detects frameshift mutagens but with lower sensitivity than the Salmonella/microsome assay.","A forward mutation assay using ampicillin-resistance in Escherichia coli designed for investigating the mutagenicity of biological samples Abs: The development of a bacterial mutation assay using forward mutation to ampicillin-resistance is described. It is a technically simple assay using Escherichia coli D494uvrB transformed with a multi-copy mutator plasmid pGW1700. Mutation is detected by an increase in the frequency of ampicillin-resistant colonies following treatment of bacteria with the test material during logarithmic growth. The determination of viable counts allows a correction factor to be applied to compensate for the effects of sample-induced growth enhancement or toxicity on the bacterial population. The assay has been tested with a range of reference mutagens. It is particularly sensitive to base-pair substitution mutagens, detecting these at doses equal to or less than those detected in the Salmonella/microsome assay or the SOS Chromotest. The assay also detects frameshift mutagens but with lower sensitivity than the Salmonella/microsome assay."
1203265,Ishii and  Yoshikawa 1993,MICROBIAL BIOASSAY OF ACUTE TOXICITY BY THE PH INHIBITION METHOD AND COMPARISON OF IC(50) (PHI) WITH LD(50) FOR RATS AND MICE,"BIOSIS COPYRIGHT: BIOL ABS. A bioassay of the toxicity of 12 test chemicals is described using Klebsiella pneumonia grown at 35êC in a medium containing potassium citrate in which the pH increased steadily as the bacteria continued to grow. The chemicals tested were nine metallic ions, two alcohols, and phenol. The pH of the medium was recorded automatically every 3.6 h for 15 h. The 50% inhibitory concentrations (IC50) of the test chemicals (mg/l) were 0.9 for Hg, 2.9 for Cd, 2.9 for Cr6+, 7.5 for Cu, 19 for Cr3+, 25 for Zn, 50 for CN, 91 for Mn, 1,430 for phenol, 53,300 for ethanol, and 74,200 for methanol. LD50 values for rats given the compounds per os and for mice given them intraperitoneally were correlated with the IC50 values obtained by this method. The method might be used in preliminary screening for toxicity before tests in experimental animals.","MICROBIAL BIOASSAY OF ACUTE TOXICITY BY THE PH INHIBITION METHOD AND COMPARISON OF IC(50) (PHI) WITH LD(50) FOR RATS AND MICE Abs: BIOSIS COPYRIGHT: BIOL ABS. A bioassay of the toxicity of 12 test chemicals is described using Klebsiella pneumonia grown at 35êC in a medium containing potassium citrate in which the pH increased steadily as the bacteria continued to grow. The chemicals tested were nine metallic ions, two alcohols, and phenol. The pH of the medium was recorded automatically every 3.6 h for 15 h. The 50% inhibitory concentrations (IC50) of the test chemicals (mg/l) were 0.9 for Hg, 2.9 for Cd, 2.9 for Cr6+, 7.5 for Cu, 19 for Cr3+, 25 for Zn, 50 for CN, 91 for Mn, 1,430 for phenol, 53,300 for ethanol, and 74,200 for methanol. LD50 values for rats given the compounds per os and for mice given them intraperitoneally were correlated with the IC50 values obtained by this method. The method might be used in preliminary screening for toxicity before tests in experimental animals."
1200188,Mckenna and  Charleston 1992,THE SURVIVAL OF SARCOCYSTIS-GIGANTEA SPOROCYSTS FOLLOWING EXPOSURE TO VARIOUS CHEMICAL AND PHYSICAL AGENTS,"Using in vitro excystation as a measure of viability, it was found that at 4 degrees C Sarcocystis gigantea sporocysts survived considerably better in tap water (85% excystation after 174 days) than in either 2.5% potassium dichromate (15% excystation after 174 days) or 2% sulphuric acid (0% excystation after 5 days). Although they were able to resist 48 h suspension at room temperature in most laboratory reagents and disinfectants tested, six (sulphuric acid, ammonia, methanol, ethanol, potassium hydroxide, sodium hydroxide, Medol) had substantial sporocysticidal properties. Further investigation with three of these showed that sporocyst excystation was reduced from 65% to less than 10% following contact with 2.5% sulphuric acid for 1 h or with 2% ammonia or 4% Medol for 4 h. Sporocysts were either killed or had their ability to excyst severely impaired by heating to 60 degrees C and 55 degrees C for 5 and 60 min, respectively, by exposure to ultraviolet radiation at a dose of 4000 ET, or by prolonged storage in water at 24 degrees C. Sporocysts exposed to either constant or intermittent freezing at -18 degrees C suffered a comparatively slow decline in excystation rate with time, as did those subjected to desiccation. The duration of survival of desiccated sporocysts was inversely related to relative humidity and after 245 days at 33% relative humidity and temperatures of 15 degrees C or 24 degrees C, 60% of such sporocysts excysted.","THE SURVIVAL OF SARCOCYSTIS-GIGANTEA SPOROCYSTS FOLLOWING EXPOSURE TO VARIOUS CHEMICAL AND PHYSICAL AGENTS Abs: Using in vitro excystation as a measure of viability, it was found that at 4 degrees C Sarcocystis gigantea sporocysts survived considerably better in tap water (85% excystation after 174 days) than in either 2.5% potassium dichromate (15% excystation after 174 days) or 2% sulphuric acid (0% excystation after 5 days). Although they were able to resist 48 h suspension at room temperature in most laboratory reagents and disinfectants tested, six (sulphuric acid, ammonia, methanol, ethanol, potassium hydroxide, sodium hydroxide, Medol) had substantial sporocysticidal properties. Further investigation with three of these showed that sporocyst excystation was reduced from 65% to less than 10% following contact with 2.5% sulphuric acid for 1 h or with 2% ammonia or 4% Medol for 4 h. Sporocysts were either killed or had their ability to excyst severely impaired by heating to 60 degrees C and 55 degrees C for 5 and 60 min, respectively, by exposure to ultraviolet radiation at a dose of 4000 ET, or by prolonged storage in water at 24 degrees C. Sporocysts exposed to either constant or intermittent freezing at -18 degrees C suffered a comparatively slow decline in excystation rate with time, as did those subjected to desiccation. The duration of survival of desiccated sporocysts was inversely related to relative humidity and after 245 days at 33% relative humidity and temperatures of 15 degrees C or 24 degrees C, 60% of such sporocysts excysted."
1191792,Branca et al. 1996,"EPR and ENDOR studies on monoanionic complexes of 1,2-semiquinones with Cr-52, Cr-53(III)",,"EPR and ENDOR studies on monoanionic complexes of 1,2-semiquinones with Cr-52, Cr-53(III) Abs: "
1189742,Posta et al. 1996,Cr(III) and Cr(VI) on-line preconcentration and high-performance flow flame emission spectrometric determination in water samples,"BIOSIS COPYRIGHT: BIOL ABS. The concentration of chromium in environmental and biological samples (ground, sea, and drinking water, blood serum, urine) is too low (0.1-1 ng/ml) to be determined directly from the sample with either flame atomic absorption, ICP, or even ICP/MS methods. To determine the Cr(III) and Cr(VI) content of these samples is even more difficult. To solve this problem we combined a high-pressure liquid chromatographic separation method with atomic spectrometric detection. In addition to the Cr(VI) preconcentration, a new on-line preconcentration/elution method with a C18 HPLC column was developed to determine the Cr(III) concentration. For the preconcentration, in the case of Cr(VI), 0.05 M tetrabutylammonium bromide was used as an ion pair forming agent while 0.075 M potassium hydrogen phthalate was used to preconcentrate Cr(III). The eluent was a methanol-water mixture of 60% or 80%, respectively. One of the most effective methods of atomic spectrometry, hydraulic high-press","Cr(III) and Cr(VI) on-line preconcentration and high-performance flow flame emission spectrometric determination in water samples Abs: BIOSIS COPYRIGHT: BIOL ABS. The concentration of chromium in environmental and biological samples (ground, sea, and drinking water, blood serum, urine) is too low (0.1-1 ng/ml) to be determined directly from the sample with either flame atomic absorption, ICP, or even ICP/MS methods. To determine the Cr(III) and Cr(VI) content of these samples is even more difficult. To solve this problem we combined a high-pressure liquid chromatographic separation method with atomic spectrometric detection. In addition to the Cr(VI) preconcentration, a new on-line preconcentration/elution method with a C18 HPLC column was developed to determine the Cr(III) concentration. For the preconcentration, in the case of Cr(VI), 0.05 M tetrabutylammonium bromide was used as an ion pair forming agent while 0.075 M potassium hydrogen phthalate was used to preconcentrate Cr(III). The eluent was a methanol-water mixture of 60% or 80%, respectively. One of the most effective methods of atomic spectrometry, hydraulic high-press"
1189672,Trevaskis and  Trenerry 1996,An investigation into the determination of oxalic acid in vegetables by capillary electrophoresis,"BIOSIS COPYRIGHT: BIOL ABS. The presence of natural levels of oxalate in foods may have important dietary implications through interference with calcium availability as well as an effect on renal stone formation. Recently, capillary electrophoresis (CE) has been used to separate a number of commonly occurring organic and inorganic anions, including oxalate. Initial attempts to determine oxalic acid by CE using an electrolyte consisting of 5 mM sodium chromate and 0.05 mM OFM Anion-BT reagent were unsuccessful in the presence of the large chloride concentration from the extract solution due to co-migration of oxalate, molybdate (chosen as the most suitable compound for use as an internal standard) and naturally occurring nitrate. Changing the composition of the electrolyte to 10 mM sodium chromate, 4 mM Anion-BT reagent and adding 10% methanol produced baseline separation of oxalate, nitrate and molybdate in vegetable extracts, despite the presence of a huge chloride peak. The levels of oxalic acid","An investigation into the determination of oxalic acid in vegetables by capillary electrophoresis Abs: BIOSIS COPYRIGHT: BIOL ABS. The presence of natural levels of oxalate in foods may have important dietary implications through interference with calcium availability as well as an effect on renal stone formation. Recently, capillary electrophoresis (CE) has been used to separate a number of commonly occurring organic and inorganic anions, including oxalate. Initial attempts to determine oxalic acid by CE using an electrolyte consisting of 5 mM sodium chromate and 0.05 mM OFM Anion-BT reagent were unsuccessful in the presence of the large chloride concentration from the extract solution due to co-migration of oxalate, molybdate (chosen as the most suitable compound for use as an internal standard) and naturally occurring nitrate. Changing the composition of the electrolyte to 10 mM sodium chromate, 4 mM Anion-BT reagent and adding 10% methanol produced baseline separation of oxalate, nitrate and molybdate in vegetable extracts, despite the presence of a huge chloride peak. The levels of oxalic acid"
1186859,Wernersson and  Dave 1997,Phototoxicity identification by solid phase extraction and photoinduced toxicity to Daphnia magna,,Phototoxicity identification by solid phase extraction and photoinduced toxicity to Daphnia magna Abs: 
1183755,Rao et al. 1998,Speciative determination of chromium(VI) and chromium(III) using flow-injection on-line preconcentration and flame atomic-absorption spectrometric detection,"BIOSIS COPYRIGHT: BIOL ABS. A rapid, sensitive and selective method for the speciative determination of chromium(VI) and chromium(III) in sea-water samples by flame atomic-absorption spectrometry, using on-line preconcentration on a micro-column packed with C18 bonded silica gel, has been developed. This is based on the selective formation of diethyldithiocarbamate complexes of chromium(VI) in the 1-2 pH range and chromium(III) in the 4-9 pH range in the presence of manganese(II) (which enhances the chromium(III) signal ten-fold). The preconcentrated species desorbed by methanol directly from the column to the nebulizer-burner system using a flow rate of 4.0 ml/min. Five hundred-fold enrichment of Cr(III) and Cr(III) was observed with a detection limit of 0.02 mug/l for a 5 min preconcentration time. The effect of probable concomitant species in seawater was determined and a satisfactory recovery of 95-105% could be obtained. Linear calibration curves were obtained for both the species, Cr(VI) and","Speciative determination of chromium(VI) and chromium(III) using flow-injection on-line preconcentration and flame atomic-absorption spectrometric detection Abs: BIOSIS COPYRIGHT: BIOL ABS. A rapid, sensitive and selective method for the speciative determination of chromium(VI) and chromium(III) in sea-water samples by flame atomic-absorption spectrometry, using on-line preconcentration on a micro-column packed with C18 bonded silica gel, has been developed. This is based on the selective formation of diethyldithiocarbamate complexes of chromium(VI) in the 1-2 pH range and chromium(III) in the 4-9 pH range in the presence of manganese(II) (which enhances the chromium(III) signal ten-fold). The preconcentrated species desorbed by methanol directly from the column to the nebulizer-burner system using a flow rate of 4.0 ml/min. Five hundred-fold enrichment of Cr(III) and Cr(III) was observed with a detection limit of 0.02 mug/l for a 5 min preconcentration time. The effect of probable concomitant species in seawater was determined and a satisfactory recovery of 95-105% could be obtained. Linear calibration curves were obtained for both the species, Cr(VI) and"
1178290,Jie et al. 1999,Ultrasound assisted synthesis of pyrazole fatty ester derivatives from a key C-18 keto-allenic ester,,Ultrasound assisted synthesis of pyrazole fatty ester derivatives from a key C-18 keto-allenic ester Abs: 
1178138,Sun et al. 1999,"Quantitative analysis of manganese, chromium and molybdenum by ion-pair reversed-phase high-performance liquid chromatography with pre-column derivatization and UV-visible detection",,"Quantitative analysis of manganese, chromium and molybdenum by ion-pair reversed-phase high-performance liquid chromatography with pre-column derivatization and UV-visible detection Abs: "
1174393,Park et al. 2012,Dual ion beam irradiation of polymeric materials for the modification of optical properties with improved adhesion,,Dual ion beam irradiation of polymeric materials for the modification of optical properties with improved adhesion Abs: 
1170236,Headlam and  Lay 2001,EPR spectroscopic studies of the reduction of chromium(VI) by methanol in the presence of peptides. Formation of long-lived chromium(V) peptide complexes,"The synthesis and characterization of the first Cr(V) complexes with non-sulfur-containing peptides, which may mimic the chemistry of the intermediates in the formation of Cr-induced peptide-DNA cross-links in vivo, are reported. The reduction of Cr(VI) with methanol in the presence of a number of non-sulfur-containing peptides produced relatively stable Cr(V)-peptide complexes, which were characterized by EPR spectroscopy and electrospray mass spectrometry. The reaction of Cr(VI) with methanol alone (in the absence of peptide ligands) resulted in the formation of two Cr(V)-methanol intermediates, with giso values of 1.9765 and 1.9687. The methanol reduction of Cr(VI) in the presence of the glycine peptides, triglycine, tetraglycine, and pentaglycine resulted in the formation of both Cr(V)-methanol and Cr(V)-peptide intermediates, while only the Cr(V)-peptide complexes were detected in the reactions with the alanine peptides trialanine, tetraalanine, and pentaalanine. Similar EPR signals were observed for all of the Cr(V)-peptide complexes with giso values between approximately 1.986 and approximately 1.979, and AN values of (2.1-2.6) x 10(-4) cm-1.","EPR spectroscopic studies of the reduction of chromium(VI) by methanol in the presence of peptides. Formation of long-lived chromium(V) peptide complexes Abs: The synthesis and characterization of the first Cr(V) complexes with non-sulfur-containing peptides, which may mimic the chemistry of the intermediates in the formation of Cr-induced peptide-DNA cross-links in vivo, are reported. The reduction of Cr(VI) with methanol in the presence of a number of non-sulfur-containing peptides produced relatively stable Cr(V)-peptide complexes, which were characterized by EPR spectroscopy and electrospray mass spectrometry. The reaction of Cr(VI) with methanol alone (in the absence of peptide ligands) resulted in the formation of two Cr(V)-methanol intermediates, with giso values of 1.9765 and 1.9687. The methanol reduction of Cr(VI) in the presence of the glycine peptides, triglycine, tetraglycine, and pentaglycine resulted in the formation of both Cr(V)-methanol and Cr(V)-peptide intermediates, while only the Cr(V)-peptide complexes were detected in the reactions with the alanine peptides trialanine, tetraalanine, and pentaalanine. Similar EPR signals were observed for all of the Cr(V)-peptide complexes with giso values between approximately 1.986 and approximately 1.979, and AN values of (2.1-2.6) x 10(-4) cm-1."
1166113,Headlam et al. 2001,Dinuclear chromium(V) amino acid complexes from the reduction of chromium(VI) in the presence of amino acid ligands: XAFS characterization of a chromium(V) amino acid complex,"The first synthesis and characterization of Cr(V) complexes of non-sulfur-containing amino acids are reported. The reduction of Cr(VI) in methanol in the presence of amino acids glycine, alanine, and 2-amino-2-methylpropanoic acid (alpha-aminoisobutyric acid, Aib) yielded several Cr(V) EPR signals. For the reaction involving glycine, the only Cr(V) EPR signals detected were those of the Cr(V)-intermediate methanol complexes, which were also observed in the absence of amino acids. The reaction involving alanine yielded one Cr(V) signal with a g(iso) value of 1.9754 (a(iso) = 4.88 x 10(-4) cm(-1) and A(iso)(53Cr) = 17.89 x 10(-4) cm(-1)). However, a solid product isolated from the reaction solution was EPR silent and was characterized as a dioxo-bridged dimeric species, [Cr(V)2(mu-O)2(O)2(Ala)2(OCH3)2](2-), by multiple-scattering XAFS analysis and electrospray mass spectrometry. The EPR spectrum of the reduction reaction of Cr(VI) in the presence of Aib showed several different Cr(V) signals. Those observed at lower g(iso) values (1.9765, 1.9806) were assigned to Cr(V)-methanol intermediates, while the relatively broad six-line signal at g(iso) = 2.0058 was assigned as being due to a Cr(V) complex with coupling to a single deprotonated amine group of the amino acid. This was confirmed by simplification of the superhyperfine coupling lines from six to three when the deuterated ligand was substituted in the reaction. The reduction of Cr(VI) with excess alanine or Aib ligands resulted in the formation of tris-chelate Cr(III) complexes, which were analytically identical to complexes formed via Cr(III) synthesis methods. The fac-[Cr(Aib)3] complex was characterized by single-crystal X-ray diffraction.","Dinuclear chromium(V) amino acid complexes from the reduction of chromium(VI) in the presence of amino acid ligands: XAFS characterization of a chromium(V) amino acid complex Abs: The first synthesis and characterization of Cr(V) complexes of non-sulfur-containing amino acids are reported. The reduction of Cr(VI) in methanol in the presence of amino acids glycine, alanine, and 2-amino-2-methylpropanoic acid (alpha-aminoisobutyric acid, Aib) yielded several Cr(V) EPR signals. For the reaction involving glycine, the only Cr(V) EPR signals detected were those of the Cr(V)-intermediate methanol complexes, which were also observed in the absence of amino acids. The reaction involving alanine yielded one Cr(V) signal with a g(iso) value of 1.9754 (a(iso) = 4.88 x 10(-4) cm(-1) and A(iso)(53Cr) = 17.89 x 10(-4) cm(-1)). However, a solid product isolated from the reaction solution was EPR silent and was characterized as a dioxo-bridged dimeric species, [Cr(V)2(mu-O)2(O)2(Ala)2(OCH3)2](2-), by multiple-scattering XAFS analysis and electrospray mass spectrometry. The EPR spectrum of the reduction reaction of Cr(VI) in the presence of Aib showed several different Cr(V) signals. Those observed at lower g(iso) values (1.9765, 1.9806) were assigned to Cr(V)-methanol intermediates, while the relatively broad six-line signal at g(iso) = 2.0058 was assigned as being due to a Cr(V) complex with coupling to a single deprotonated amine group of the amino acid. This was confirmed by simplification of the superhyperfine coupling lines from six to three when the deuterated ligand was substituted in the reaction. The reduction of Cr(VI) with excess alanine or Aib ligands resulted in the formation of tris-chelate Cr(III) complexes, which were analytically identical to complexes formed via Cr(III) synthesis methods. The fac-[Cr(Aib)3] complex was characterized by single-crystal X-ray diffraction."
1162161,Thomas et al. 2002,Determination of hexavalent chromium at the level of the California Public Health Goal by ion chromatography,"Chromium is a primary drinking water contaminant in the USA with hexavalent chromium, Cr(VI), being the most toxic form of the metal. As a required step in developing a revised state drinking water standard for chromium, the California Department of Health Services recently issued a new Public Health Goal (PHG) of 2.5 microg/l for total chromium and 0.2 microg/l for Cr(VI). Hexavalent chromium can be determined (as chromate) by ion chromatography, as described in US Evironmental Protection Agency Method 218.6; however, the method as originally published does not allow sufficient sensitivity for analysis at the California PHG level of 0.2 microg/l. Modification of the conditions described in Method 218.6, including the use of a lower eluent flow-rate, larger reaction coil, and larger injection volume, significantly increases the method sensitivity. The modified method, which uses IonPac NG1 and AS7 guard and analytical columns, an eluent of 250 mM ammonium sulfate-100 mM ammonium hydroxide operated at 1.0 ml/min, a 1000 microl injection volume, and postcolumn reaction with 2 mM diphenylcarbazide-10% methanol-0.5 M sulfuric acid (using a 750 microl reaction coil) followed by UV-Vis detection at 530 nm, permits a method detection limit for chromate of 0.02 microg/l. This results in a quantitation limit of 0.06 microg/l, which is more than sufficient for analysis at the California PHG level. Calibration is linear over the range of 0.1-10 microg/l and quantitative recoveries (&gt;80%) are obtained for chromate spiked at 0.2 microg/l in drinking water. The modified method provides acceptable performance, in terms of chromate peak shape and recovery, in the presence of up to 1000 mg/l chloride or 2000 mg/l sulfate.","Determination of hexavalent chromium at the level of the California Public Health Goal by ion chromatography Abs: Chromium is a primary drinking water contaminant in the USA with hexavalent chromium, Cr(VI), being the most toxic form of the metal. As a required step in developing a revised state drinking water standard for chromium, the California Department of Health Services recently issued a new Public Health Goal (PHG) of 2.5 microg/l for total chromium and 0.2 microg/l for Cr(VI). Hexavalent chromium can be determined (as chromate) by ion chromatography, as described in US Evironmental Protection Agency Method 218.6; however, the method as originally published does not allow sufficient sensitivity for analysis at the California PHG level of 0.2 microg/l. Modification of the conditions described in Method 218.6, including the use of a lower eluent flow-rate, larger reaction coil, and larger injection volume, significantly increases the method sensitivity. The modified method, which uses IonPac NG1 and AS7 guard and analytical columns, an eluent of 250 mM ammonium sulfate-100 mM ammonium hydroxide operated at 1.0 ml/min, a 1000 microl injection volume, and postcolumn reaction with 2 mM diphenylcarbazide-10% methanol-0.5 M sulfuric acid (using a 750 microl reaction coil) followed by UV-Vis detection at 530 nm, permits a method detection limit for chromate of 0.02 microg/l. This results in a quantitation limit of 0.06 microg/l, which is more than sufficient for analysis at the California PHG level. Calibration is linear over the range of 0.1-10 microg/l and quantitative recoveries (&gt;80%) are obtained for chromate spiked at 0.2 microg/l in drinking water. The modified method provides acceptable performance, in terms of chromate peak shape and recovery, in the presence of up to 1000 mg/l chloride or 2000 mg/l sulfate."
1151004,Garcia et al. 2010,ABS polymer electroless plating through a one-step poly(acrylic acid) covalent grafting,"A new, efficient, palladium- and chromium-free process for the electroless plating of acrylonitrile-butadiene-styrene (ABS) polymers has been developed. The process is based on the ion-exchange properties of poly(acrylic acid) (PAA) chemically grafted onto ABS via a simple and one-step method that prevents using classical surface conditioning. Hence, ABS electroless plating can be obtained in three steps, namely: (i) the grafting of PAA onto ABS, (ii) the copper Cu(0) seeding of the ABS surface, and (iii) the nickel or copper metallization using commercial-like electroless plating bath. IR, XPS, and SEM were used to characterize each step of the process, and the Cu loading was quantified by atomic absorption spectroscopy. This process successfully compares with the commercial one based on chromic acid etching and palladium-based seed layer, because the final metallic layer showed excellent adhesion with the ABS substrate.","ABS polymer electroless plating through a one-step poly(acrylic acid) covalent grafting Abs: A new, efficient, palladium- and chromium-free process for the electroless plating of acrylonitrile-butadiene-styrene (ABS) polymers has been developed. The process is based on the ion-exchange properties of poly(acrylic acid) (PAA) chemically grafted onto ABS via a simple and one-step method that prevents using classical surface conditioning. Hence, ABS electroless plating can be obtained in three steps, namely: (i) the grafting of PAA onto ABS, (ii) the copper Cu(0) seeding of the ABS surface, and (iii) the nickel or copper metallization using commercial-like electroless plating bath. IR, XPS, and SEM were used to characterize each step of the process, and the Cu loading was quantified by atomic absorption spectroscopy. This process successfully compares with the commercial one based on chromic acid etching and palladium-based seed layer, because the final metallic layer showed excellent adhesion with the ABS substrate."
1141999,Yang et al. 1996,Direct Speciation of Selenite and Selenate with Thermospray Sample Introduction Methods,"The speciation of selenite (Se4) and selenate (Se6) with thermospray nebulization and inductively coupled plasma atomic emission spectrometry (ICP-AES) detection was reported. The effects of methanol, nitric-acid, and oxidant concentrations, and potential interferences from concomitants were described. When ICP-AES was used under aqueous conditions, the sensitivity to Se4 was one fourth that of Se6. Sensitivity for Se4, but not for Se6, was found to be reduced by addition of methanol to the mobile phase. The Se6e4 sensitivity ratio increased with methanol concentration and reached about 1000 at a methanol concentration of 10 to 50% volume/volume (v/v), allowing for the selective determination of Se6 in a sample with methanol added. Inspection of the thermospray nebulizer showed a deposition of metallic selenium formed by reduction of Se4 to selenium. The sensitivity of Se4 was highly dependent on the concentration of nitric-acid in 20% (v/v) methanol solution; Se4's sensitivity was sharply decreased due to a low concentration of nitric-acid (16.0 millimoles/liter (mmol/l)), while at nitric-acid concentrations above 0.016mmol/l, the reduction of Se4 by methanol was counterbalanced by nitric-acid oxidation. Se6 was found to be insignificantly affected by variations in nitric-acid concentration. Oxidizing reagents were added, and results indicated that an increase in the concentration of the oxidants potassium-dichromate or potassium-persulfate resulted in an increase in the sensitivity of Se4; at oxidant concentrations of 2.0mmol/l potassium-dichromate, and at 1.0mmol/l potassium-persulfate, Se4 sensitivity became equal to that for Se6. Under these conditions no reduction of Se4 or Se6 was observed. Interference studies with nickel(2) (Ni2), tin(2) (Sn2), and chromium(6) (Cr6) on the determination of Se6 and total selenium showed no effect by Ni2, and minimal interference by Sn2 and Cr6. A detection limit of 9.0 nanograms Se6/milliliter (ng/ml) was achieved containing 20% (v/v) methanol, compared to a limit of 2ng/ml for aqueous samples. Satisfactory results were obtained when spiked tap water was analyzed for Se4 and Se6 concentrations by first determining total selenium in a sample containing an oxidizer, then determining Se6 concentration in a sample to which methanol was added. The difference in the two readings was attributed to the concentration of Se4. The authors conclude that the described method provides a viable alternative for quantitative analysis of selenium species.","Direct Speciation of Selenite and Selenate with Thermospray Sample Introduction Methods Abs: The speciation of selenite (Se4) and selenate (Se6) with thermospray nebulization and inductively coupled plasma atomic emission spectrometry (ICP-AES) detection was reported. The effects of methanol, nitric-acid, and oxidant concentrations, and potential interferences from concomitants were described. When ICP-AES was used under aqueous conditions, the sensitivity to Se4 was one fourth that of Se6. Sensitivity for Se4, but not for Se6, was found to be reduced by addition of methanol to the mobile phase. The Se6e4 sensitivity ratio increased with methanol concentration and reached about 1000 at a methanol concentration of 10 to 50% volume/volume (v/v), allowing for the selective determination of Se6 in a sample with methanol added. Inspection of the thermospray nebulizer showed a deposition of metallic selenium formed by reduction of Se4 to selenium. The sensitivity of Se4 was highly dependent on the concentration of nitric-acid in 20% (v/v) methanol solution; Se4's sensitivity was sharply decreased due to a low concentration of nitric-acid (16.0 millimoles/liter (mmol/l)), while at nitric-acid concentrations above 0.016mmol/l, the reduction of Se4 by methanol was counterbalanced by nitric-acid oxidation. Se6 was found to be insignificantly affected by variations in nitric-acid concentration. Oxidizing reagents were added, and results indicated that an increase in the concentration of the oxidants potassium-dichromate or potassium-persulfate resulted in an increase in the sensitivity of Se4; at oxidant concentrations of 2.0mmol/l potassium-dichromate, and at 1.0mmol/l potassium-persulfate, Se4 sensitivity became equal to that for Se6. Under these conditions no reduction of Se4 or Se6 was observed. Interference studies with nickel(2) (Ni2), tin(2) (Sn2), and chromium(6) (Cr6) on the determination of Se6 and total selenium showed no effect by Ni2, and minimal interference by Sn2 and Cr6. A detection limit of 9.0 nanograms Se6/milliliter (ng/ml) was achieved containing 20% (v/v) methanol, compared to a limit of 2ng/ml for aqueous samples. Satisfactory results were obtained when spiked tap water was analyzed for Se4 and Se6 concentrations by first determining total selenium in a sample containing an oxidizer, then determining Se6 concentration in a sample to which methanol was added. The difference in the two readings was attributed to the concentration of Se4. The authors conclude that the described method provides a viable alternative for quantitative analysis of selenium species."
1117900,Cock and  Kalt 2010,Toxicity evaluation of Xanthorrhoea johnsonii leaf methanolic extract using the Artemia franciscana bioassay,"The toxicity of Xanthorrhoea johnsonii methanolic leaf extract was investigated using the Artemia franciscana nauplii bioassay. At 24 h, the extract produced an EC(50) of 361.0 ± 41.8 ?g/ml, indicating that it was substantially more toxic than the pesticide Mevinphos (1346.2 ± 80.1 ?g/ml) and approximately 4 fold less toxic than potassium dichromate (87.1 ± 5.2 ?g/ml). Whilst potassium dichromate LC(50) values remained constant across the 72-h test period, these values decreased for the extract and Mevinphos to similar values (199.8 ± 60.5 and 114 ± 12.8 ?g/ml, respectively), indicating their similar level of efficacy. Noteworthy was the apparent anesthetic effect of X. johnsonii leaf extract. Although the extract initially appeared to kill the A. franciscana nauplii, they were seen to temporarily recover by 48 h only to die by 72 h.","Toxicity evaluation of Xanthorrhoea johnsonii leaf methanolic extract using the Artemia franciscana bioassay Abs: The toxicity of Xanthorrhoea johnsonii methanolic leaf extract was investigated using the Artemia franciscana nauplii bioassay. At 24 h, the extract produced an EC(50) of 361.0 ± 41.8 ?g/ml, indicating that it was substantially more toxic than the pesticide Mevinphos (1346.2 ± 80.1 ?g/ml) and approximately 4 fold less toxic than potassium dichromate (87.1 ± 5.2 ?g/ml). Whilst potassium dichromate LC(50) values remained constant across the 72-h test period, these values decreased for the extract and Mevinphos to similar values (199.8 ± 60.5 and 114 ± 12.8 ?g/ml, respectively), indicating their similar level of efficacy. Noteworthy was the apparent anesthetic effect of X. johnsonii leaf extract. Although the extract initially appeared to kill the A. franciscana nauplii, they were seen to temporarily recover by 48 h only to die by 72 h."
1094263,Wang et al. 2010,Roles of MAPK pathway activation during cytokine induction in BEAS-2B cells exposed to fine World Trade Center (WTC) dust,"The World Trade Center (WTC) collapse on September 11, 2001 released copious amounts of particulate matter (PM) into the atmosphere of New York City. Follow-up studies on persons exposed to the dusts have revealed a severely increased rate for asthma and other respiratory illnesses. There have only been a few studies that have sought to discern the possible mechanisms underlying these untoward pathologies. In one study, an increased cytokine release was detected in cells exposed to WTC fine dusts (PM?.? fraction or WTC?.?). However, the mechanism(s) for these increases has yet to be fully defined. Because activation of the mitogen-activated protein kinase (MAPK) signaling pathways is known to cause cytokine induction, the current study was undertaken to analyze the possible involvement of these pathways in any increased cytokine formation by lung epithelial cells (as BEAS-2B cells) exposed to WTC?.?. Our results showed that exposure to WTC?.? for 5?hr increased interleukin-6 (IL-6) mRNA expression in BEAS-2B cells, as well as its protein levels in the culture media, in a dose-dependent manner. Besides IL-6, cytokine multiplex analyses revealed that formation of IL-8 and -10 was also elevated by the exposure. Both extracellular signal-regulated kinase (ERK) and p38, but not c-Jun N-terminal protein kinase, signaling pathways were found to be activated in cells exposed to WTC?.?. Inactivation of ERK signaling pathways by PD98059 effectively blocked IL-6, -8, and -10 induction by WTC?.?; the p38 kinase inhibitor SB203580 significantly decreased induction of IL-8 and -10. Together, our data demonstrated activation of MAPK signaling pathway(s) likely played an important role in the WTC?.?-induced formation of several inflammatory (and, subsequently, anti-inflammatory) cytokines. The results are important in that they help to define one mechanism via which the WTC dusts may have acted to cause the documented increases in asthma and other inflammation-associated respiratory dysfunctions in the individuals exposed to the dusts released from the WTC collapse.","Roles of MAPK pathway activation during cytokine induction in BEAS-2B cells exposed to fine World Trade Center (WTC) dust Abs: The World Trade Center (WTC) collapse on September 11, 2001 released copious amounts of particulate matter (PM) into the atmosphere of New York City. Follow-up studies on persons exposed to the dusts have revealed a severely increased rate for asthma and other respiratory illnesses. There have only been a few studies that have sought to discern the possible mechanisms underlying these untoward pathologies. In one study, an increased cytokine release was detected in cells exposed to WTC fine dusts (PM?.? fraction or WTC?.?). However, the mechanism(s) for these increases has yet to be fully defined. Because activation of the mitogen-activated protein kinase (MAPK) signaling pathways is known to cause cytokine induction, the current study was undertaken to analyze the possible involvement of these pathways in any increased cytokine formation by lung epithelial cells (as BEAS-2B cells) exposed to WTC?.?. Our results showed that exposure to WTC?.? for 5?hr increased interleukin-6 (IL-6) mRNA expression in BEAS-2B cells, as well as its protein levels in the culture media, in a dose-dependent manner. Besides IL-6, cytokine multiplex analyses revealed that formation of IL-8 and -10 was also elevated by the exposure. Both extracellular signal-regulated kinase (ERK) and p38, but not c-Jun N-terminal protein kinase, signaling pathways were found to be activated in cells exposed to WTC?.?. Inactivation of ERK signaling pathways by PD98059 effectively blocked IL-6, -8, and -10 induction by WTC?.?; the p38 kinase inhibitor SB203580 significantly decreased induction of IL-8 and -10. Together, our data demonstrated activation of MAPK signaling pathway(s) likely played an important role in the WTC?.?-induced formation of several inflammatory (and, subsequently, anti-inflammatory) cytokines. The results are important in that they help to define one mechanism via which the WTC dusts may have acted to cause the documented increases in asthma and other inflammation-associated respiratory dysfunctions in the individuals exposed to the dusts released from the WTC collapse."
1090801,Popper et al. 1993,Cytotoxicity of chromium-III and chromium-VI compounds. I. In vitro studies using different cell culture systems,"The cytotoxic effects of chromium-3 (Cr-3; as chloride, CrCl3) and -6 compounds (chromates as chromium trioxide, CrO3; barium and lead chromates, BaCrO4, PbCrO4; and as potassium dichromate, K2Cr2O7) were tested in an in vitro test battery. V79 hamster lung fibroblasts, rat pneumocytes type II (LEC), human adenocarcinoma cell line (A549), and guinea pig alveolar macrophages (AM) were incubated with different concentrations of Cr-3 and chromates, respectively. Cr-3 caused no cytotoxic damage to the cells, whereas chromates caused a dose-dependent cytotoxicity. Both Cr-3 and chromates were demonstrated by atomic absorption within the cell. Supernatants from AM experiments were shown to contain no fibroblast activating stimuli. It could be assumed that chromates have no fibrogenic properties. In addition, fibroblast growth and cell division were inhibited by chromates but not by Cr-3, as demonstrated by reduced uptake and nuclear incorporation of bromium desoxyuridine (BrDU) into fibroblasts. A prevention of cell cytotoxicity was attempted using superoxide dismutase (SOD) catalase, reduced glutathione (GSH), dithiothreitol (DTT) dimethyl sulfoxide (DMSO), EDTA, butylated hydroxytoluene (BHT), desferoxamine, alpha-tocopherol, and Trolox, respectively. Neither SOD, catalase, DMSO, EDTA, nor GSH prevented cell cytotoxicity in V79 or LEC cell cultures. However, DTT, which is intracellularly metabolized to glutathione, was able to reduce chromate-induced cell cytotoxicity, as did the radical scavengers BHT, desferoxamine, and Trolox, a water-soluble alpha-tocopherol derivate. Chromate cytotoxicity was therefore assumed to be mediated via the decrease of the intracellular GSH pool by either an overwhelming oxidation of GSH and/or inhibition of glutathione reductase. However, an additional mechanism or chromate-induced cytotoxicity must be assumed, because antioxidants were not able to inhibit completely toxic injury of the cells.","Cytotoxicity of chromium-III and chromium-VI compounds. I. In vitro studies using different cell culture systems Abs: The cytotoxic effects of chromium-3 (Cr-3; as chloride, CrCl3) and -6 compounds (chromates as chromium trioxide, CrO3; barium and lead chromates, BaCrO4, PbCrO4; and as potassium dichromate, K2Cr2O7) were tested in an in vitro test battery. V79 hamster lung fibroblasts, rat pneumocytes type II (LEC), human adenocarcinoma cell line (A549), and guinea pig alveolar macrophages (AM) were incubated with different concentrations of Cr-3 and chromates, respectively. Cr-3 caused no cytotoxic damage to the cells, whereas chromates caused a dose-dependent cytotoxicity. Both Cr-3 and chromates were demonstrated by atomic absorption within the cell. Supernatants from AM experiments were shown to contain no fibroblast activating stimuli. It could be assumed that chromates have no fibrogenic properties. In addition, fibroblast growth and cell division were inhibited by chromates but not by Cr-3, as demonstrated by reduced uptake and nuclear incorporation of bromium desoxyuridine (BrDU) into fibroblasts. A prevention of cell cytotoxicity was attempted using superoxide dismutase (SOD) catalase, reduced glutathione (GSH), dithiothreitol (DTT) dimethyl sulfoxide (DMSO), EDTA, butylated hydroxytoluene (BHT), desferoxamine, alpha-tocopherol, and Trolox, respectively. Neither SOD, catalase, DMSO, EDTA, nor GSH prevented cell cytotoxicity in V79 or LEC cell cultures. However, DTT, which is intracellularly metabolized to glutathione, was able to reduce chromate-induced cell cytotoxicity, as did the radical scavengers BHT, desferoxamine, and Trolox, a water-soluble alpha-tocopherol derivate. Chromate cytotoxicity was therefore assumed to be mediated via the decrease of the intracellular GSH pool by either an overwhelming oxidation of GSH and/or inhibition of glutathione reductase. However, an additional mechanism or chromate-induced cytotoxicity must be assumed, because antioxidants were not able to inhibit completely toxic injury of the cells."
1088967,Dennis et al. 1997,"The effects of welding parameters on ultra-violet light emissions, ozone and CrVI formation in MIG welding","This paper describes the relationships between ultra-violet emission, ozone generation and CrVI production in MIG welding which were measured as a function of shield gas flow rate, welding voltage, electrode stick-out and shield gas composition using an automatic welding rig that permitted MIG welding under reproducible conditions. The experimental results are interpreted in terms of the physico-chemical processes occurring in the micro- and macro-environments of the arc as part of research into process modification to reduce occupational exposure to ozone and CrVI production rates in MIG welding. We believe the techniques described here, and in particular the use of what we have termed u.v.-ozone measurements, will prove useful in further study of ozone generation and CrVI formation and may be applied in the investigation of engineering control of occupational exposure in MIG and other welding process such as Manual Metal Arc (MMA) and Tungsten Inert Gas (TIG).","The effects of welding parameters on ultra-violet light emissions, ozone and CrVI formation in MIG welding Abs: This paper describes the relationships between ultra-violet emission, ozone generation and CrVI production in MIG welding which were measured as a function of shield gas flow rate, welding voltage, electrode stick-out and shield gas composition using an automatic welding rig that permitted MIG welding under reproducible conditions. The experimental results are interpreted in terms of the physico-chemical processes occurring in the micro- and macro-environments of the arc as part of research into process modification to reduce occupational exposure to ozone and CrVI production rates in MIG welding. We believe the techniques described here, and in particular the use of what we have termed u.v.-ozone measurements, will prove useful in further study of ozone generation and CrVI formation and may be applied in the investigation of engineering control of occupational exposure in MIG and other welding process such as Manual Metal Arc (MMA) and Tungsten Inert Gas (TIG)."
1085802,White et al. 1983,Response of bovine alveolar macrophages in vitro to welding fume particles,"Alveolar macrophages (AM) from bovine lungs were exposed in culture to manual metal are (MMA) welding fume particles, chromium (Cr), UICC chrysotile A or anatase for 17-20 hr. All the welding particle samples were more cytotoxic to AM than to anatase. Particles from the welding of mild steel with a rutile-coated electrode were less cytotoxic than those produced with a basic-coated electrode. Particles from the welding of stainless steel were slightly more cytotoxic, and much of this activity was probably due to CrVI. Selective release of N-acetyl-beta-glucosaminidase (beta-NAG) was only detected after exposure of AM to chrysotile. Supplementation of the incubation medium with 10% serum increased the viability of all exposed AM cultures, an effect not produced by serum albumin alone. Incubation of particle samples with dipalmitoyl phosphatidylcholine (DPPC) prior to addition to AM reduced the cytotoxicity of the &quot;rutile&quot; welding particles and of chrysotile.","Response of bovine alveolar macrophages in vitro to welding fume particles Abs: Alveolar macrophages (AM) from bovine lungs were exposed in culture to manual metal are (MMA) welding fume particles, chromium (Cr), UICC chrysotile A or anatase for 17-20 hr. All the welding particle samples were more cytotoxic to AM than to anatase. Particles from the welding of mild steel with a rutile-coated electrode were less cytotoxic than those produced with a basic-coated electrode. Particles from the welding of stainless steel were slightly more cytotoxic, and much of this activity was probably due to CrVI. Selective release of N-acetyl-beta-glucosaminidase (beta-NAG) was only detected after exposure of AM to chrysotile. Supplementation of the incubation medium with 10% serum increased the viability of all exposed AM cultures, an effect not produced by serum albumin alone. Incubation of particle samples with dipalmitoyl phosphatidylcholine (DPPC) prior to addition to AM reduced the cytotoxicity of the &quot;rutile&quot; welding particles and of chrysotile."
1085792,Stern and  Pigott 1983,In vitro RPM fibrogenic potential assay of welding fumes,"The fibrogenic potential of 11 different welding fumes and metallic aerosols, considered to be reference standard surrogates for the commonly used welding technologies and applications responsible for 70% of welders exposure, is screened by using the rat peritoneal macrophage (RPM) in vitro bioassay. Only one class of fumes, that from the manual metal are welding of stainless steel, shows distinct fibrogenic potential. This fume, however, is not common to more than four or five of the heretofore 90 cases of pulmonary fibrosis reported among welders. Thus, although insoluble Cr(VI) is probably the active fibrogen in stainless steel fumes, an etiological factor common to all fibrogenic welding exposures must be sought; it is tentatively proposed to be NO chi, a potent experimental in vivo fibrogen copiously produced by certain welding processes and ubiquitous at low concentrations in the welding environment.","In vitro RPM fibrogenic potential assay of welding fumes Abs: The fibrogenic potential of 11 different welding fumes and metallic aerosols, considered to be reference standard surrogates for the commonly used welding technologies and applications responsible for 70% of welders exposure, is screened by using the rat peritoneal macrophage (RPM) in vitro bioassay. Only one class of fumes, that from the manual metal are welding of stainless steel, shows distinct fibrogenic potential. This fume, however, is not common to more than four or five of the heretofore 90 cases of pulmonary fibrosis reported among welders. Thus, although insoluble Cr(VI) is probably the active fibrogen in stainless steel fumes, an etiological factor common to all fibrogenic welding exposures must be sought; it is tentatively proposed to be NO chi, a potent experimental in vivo fibrogen copiously produced by certain welding processes and ubiquitous at low concentrations in the welding environment."
1085318,Pasanen et al. 1986,Cytotoxic effects of four types of welding fumes on macrophages in vitro: A comparative study,"The effects of fume particles given off by the manual metal arc (MMA) and metal inert gas (MIG) welding of stainless steel (SS) and mild steel (MS) were studied on rat alveolar macrophage cultures in vitro. The fumes were generated by welding, and particulate material obtained was collected on membrane filters. The macrophage cultures were exposed to the total dust and to its water-insoluble fractions. Cell variability and the release of both lactate dehydrogenase and one lysosomal enzyme from the cells to the medium were measured after an exposure period of 24 h. The cytotoxic control dust was DQ 12 quartz, and the inert control dust was pure titanium dioxide. According to the parameters studied, SS/MMA and MS/MMA welding fumes were cytotoxic to rat alveolar macrophages. The cytotoxic effect of SS/MMA welding fumes decreased after the samples had been washed with phosphate-buffered salt solution. The MIG welding fumes of SS and MS had markedly smaller effects on the cells. Diluted solutions of potassium chromate were also tested in order to investigate its role in the cytotoxicity of SS/MMA welding fumes. The results suggest that hexavalent chromium may be responsible for the cytotoxicity of SS/MMA.","Cytotoxic effects of four types of welding fumes on macrophages in vitro: A comparative study Abs: The effects of fume particles given off by the manual metal arc (MMA) and metal inert gas (MIG) welding of stainless steel (SS) and mild steel (MS) were studied on rat alveolar macrophage cultures in vitro. The fumes were generated by welding, and particulate material obtained was collected on membrane filters. The macrophage cultures were exposed to the total dust and to its water-insoluble fractions. Cell variability and the release of both lactate dehydrogenase and one lysosomal enzyme from the cells to the medium were measured after an exposure period of 24 h. The cytotoxic control dust was DQ 12 quartz, and the inert control dust was pure titanium dioxide. According to the parameters studied, SS/MMA and MS/MMA welding fumes were cytotoxic to rat alveolar macrophages. The cytotoxic effect of SS/MMA welding fumes decreased after the samples had been washed with phosphate-buffered salt solution. The MIG welding fumes of SS and MS had markedly smaller effects on the cells. Diluted solutions of potassium chromate were also tested in order to investigate its role in the cytotoxicity of SS/MMA welding fumes. The results suggest that hexavalent chromium may be responsible for the cytotoxicity of SS/MMA."
1084788,Donaldson and  Brown 1988,Assessment of mineral dust cytotoxicity toward rat alveolar macrophages using a 51Cr release assay,"An assay was developed to assess the cytotoxicity of mineral dust by measuring release of 51Cr from prelabeled rat alveolar macrophages. Optimal conditions for the assay are described, the most notable being use of 2% albumin instead of fetal calf serum. The assay demonstrated loss of label into the supernatant when prelabeled macrophages were cultured with the two pathogenic mineral dusts, quartz and chrysotile asbestos. In contrast the inert mineral dust titanium dioxide had very little effect on 51Cr release by rat alveolar macrophages.","Assessment of mineral dust cytotoxicity toward rat alveolar macrophages using a 51Cr release assay Abs: An assay was developed to assess the cytotoxicity of mineral dust by measuring release of 51Cr from prelabeled rat alveolar macrophages. Optimal conditions for the assay are described, the most notable being use of 2% albumin instead of fetal calf serum. The assay demonstrated loss of label into the supernatant when prelabeled macrophages were cultured with the two pathogenic mineral dusts, quartz and chrysotile asbestos. In contrast the inert mineral dust titanium dioxide had very little effect on 51Cr release by rat alveolar macrophages."
1083494,Kováciková and  Ginter 1995,Effect of ascorbic acid supplementation during the inhalation exposure of guinea-pigs to industrial dust on bronchoalveolar lavage and pulmonary enzymes,"The aim of this study was to investigate the interaction between ascorbic acid (AA) and inhaled particles separated from the dumped waste of a nickel smelter and refinery. Tricoloured male guinea pigs were exposed in an inhalation chamber to 50 mg kg-1 of < 5 microns particles that mainly consisted of metal oxides. Exposure lasted for 4 weeks (5 days per week and 5 h per day). The drinking water of half of the exposed and half of the control groups was supplemented with 1 g l-1 AA. Each group received 0.4 mmol kg-1 AA in their food. Ascorbic acid supplementation increased the pulmonary AA concentration in both exposed and control groups to the same extent, but in bronchoalveolar lavage fluid the increase was higher in control than in exposed guinea pigs. The number of alveolar macrophages was increased by exposure and AA increased the number only in the exposed group; the acid phosphatase activity of the alveolar macrophages was increased only by AA, and more in the exposed than in the control group. Alkaline phosphatase activity in bronchoalveolar lavage fluid was the same in both supplemented groups, but it was enhanced in the exposed group with a low intake of AA. Effects on lactate dehydrogenase were not consistent. Neither exposure nor AA influenced significantly this enzyme in bronchoalveolar lavage fluid, but in the lung both AA and exposure caused an increase in the activity. The levels were similar in the AA-treated control and exposed guinea pigs.","Effect of ascorbic acid supplementation during the inhalation exposure of guinea-pigs to industrial dust on bronchoalveolar lavage and pulmonary enzymes Abs: The aim of this study was to investigate the interaction between ascorbic acid (AA) and inhaled particles separated from the dumped waste of a nickel smelter and refinery. Tricoloured male guinea pigs were exposed in an inhalation chamber to 50 mg kg-1 of < 5 microns particles that mainly consisted of metal oxides. Exposure lasted for 4 weeks (5 days per week and 5 h per day). The drinking water of half of the exposed and half of the control groups was supplemented with 1 g l-1 AA. Each group received 0.4 mmol kg-1 AA in their food. Ascorbic acid supplementation increased the pulmonary AA concentration in both exposed and control groups to the same extent, but in bronchoalveolar lavage fluid the increase was higher in control than in exposed guinea pigs. The number of alveolar macrophages was increased by exposure and AA increased the number only in the exposed group; the acid phosphatase activity of the alveolar macrophages was increased only by AA, and more in the exposed than in the control group. Alkaline phosphatase activity in bronchoalveolar lavage fluid was the same in both supplemented groups, but it was enhanced in the exposed group with a low intake of AA. Effects on lactate dehydrogenase were not consistent. Neither exposure nor AA influenced significantly this enzyme in bronchoalveolar lavage fluid, but in the lung both AA and exposure caused an increase in the activity. The levels were similar in the AA-treated control and exposed guinea pigs."
1080200,Farmer et al. 2006,The implications of integrated assessment and modelling studies for the future remediation of chromite ore processing residue disposal sites,"Chromite ore processing residue (COPR) waste from a former chromium chemical works (1830-1968) is still contaminating groundwater in Glasgow, Scotland, with carcinogenic hexavalent chromium, Cr(VI). An integrated analytical, experimental and modelling approach has identified and accounted for mineral phases and processes responsible for the retention and release of Cr(VI) under prevailing field conditions. Both the nature of mineral phase retention and the buffered high pH of the sites, however, militate against direct remediative treatment of the source material, for example by the application of generic methods (e.g. FeSO4) that have been successfully employed elsewhere for the reduction of Cr(VI) to Cr(III) in other matrices. The interception and treatment of groundwater to remove Cr(VI) and the capping of sites to reduce human exposure to airborne Cr(VI)-contaminated dust may well be more realistic and effective, at least in the short to medium term.","The implications of integrated assessment and modelling studies for the future remediation of chromite ore processing residue disposal sites Abs: Chromite ore processing residue (COPR) waste from a former chromium chemical works (1830-1968) is still contaminating groundwater in Glasgow, Scotland, with carcinogenic hexavalent chromium, Cr(VI). An integrated analytical, experimental and modelling approach has identified and accounted for mineral phases and processes responsible for the retention and release of Cr(VI) under prevailing field conditions. Both the nature of mineral phase retention and the buffered high pH of the sites, however, militate against direct remediative treatment of the source material, for example by the application of generic methods (e.g. FeSO4) that have been successfully employed elsewhere for the reduction of Cr(VI) to Cr(III) in other matrices. The interception and treatment of groundwater to remove Cr(VI) and the capping of sites to reduce human exposure to airborne Cr(VI)-contaminated dust may well be more realistic and effective, at least in the short to medium term."
1080096,Mwinyihija et al. 2006,Ecotoxicological screening of Kenyan tannery dust using a luminescent-based bacterial biosensor,"Ecotoxicological screening of dust sampled throughout a Kenyan tannery was conducted using a luminescence (lux)-based bacterial biosensor for both solid and liquid assays. This was complemented by chemical analysis in an attempt to identify possible causative toxic components. The biosensor results showed a highly significant (p &lt; 0.001) difference in both solid and liquid phase toxicity in samples collected from various identified sampling points in the tannery. A positive correlation was observed between results of the solid and liquid phase techniques, for most of the sampling points indicating that the toxic contaminants were bioavailable both in the solid and liquid state. However, the results generally indicated toxicity associated with liquid phase except certain areas in solid phase such as chemical handling, buffing area and weighing. The most toxic tannery area identified was the weighing area (p &lt; 0.001), showing the lowest bioluminescence for both the solid (0.38 +/- 2.21) and liquid phases (0.01 +/- 0.001). Chromium was the metal present in the highest concentration indicating levels higher than the stipulated regulatory requirement of 0.5 mg Cr/m3 for total Cr (highest Cr concentration was at chemical handling at 209.24 mg l(-1)) in all dust samples. The weighing area had the highest Ni concentration (1.87 mg l(-1)) and the chemical handling area showed the highest Zn concentration (31.9 mg l(-1)). These results raise environmental health concerns, as occupational exposure to dust samples from this site has been shown to give rise to elevated concentrations (above the stipulated levels) of chromium in blood, urine and some body tissues, with inhalation being the main route. Health and Safety Executive (HSE), UK, and American Conference of Governmental Industrial Hygienist (ACGIH) and National Institute for Occupational Safety and Health (NIOSH), USA stipulates an occupational exposure limit of 0.5 mg Cr/m3 (8 h TWA) for total chromium. However, schedule 1 of Controls of substances hazardous to health (COSHH) regulations developed by HSE, indicate 0.05 mg m3 (8 h TWA reference periods) to be the limit for Cr (VI) exposure. The exposure limit for individual (e.g., Cr, Zn, Ni etc.) contaminants (homogeneity) was not exceeded, but potential impact of heterogeneity (multi-element synergistic effect) on toxicity requires application of the precautionary principle.","Ecotoxicological screening of Kenyan tannery dust using a luminescent-based bacterial biosensor Abs: Ecotoxicological screening of dust sampled throughout a Kenyan tannery was conducted using a luminescence (lux)-based bacterial biosensor for both solid and liquid assays. This was complemented by chemical analysis in an attempt to identify possible causative toxic components. The biosensor results showed a highly significant (p &lt; 0.001) difference in both solid and liquid phase toxicity in samples collected from various identified sampling points in the tannery. A positive correlation was observed between results of the solid and liquid phase techniques, for most of the sampling points indicating that the toxic contaminants were bioavailable both in the solid and liquid state. However, the results generally indicated toxicity associated with liquid phase except certain areas in solid phase such as chemical handling, buffing area and weighing. The most toxic tannery area identified was the weighing area (p &lt; 0.001), showing the lowest bioluminescence for both the solid (0.38 +/- 2.21) and liquid phases (0.01 +/- 0.001). Chromium was the metal present in the highest concentration indicating levels higher than the stipulated regulatory requirement of 0.5 mg Cr/m3 for total Cr (highest Cr concentration was at chemical handling at 209.24 mg l(-1)) in all dust samples. The weighing area had the highest Ni concentration (1.87 mg l(-1)) and the chemical handling area showed the highest Zn concentration (31.9 mg l(-1)). These results raise environmental health concerns, as occupational exposure to dust samples from this site has been shown to give rise to elevated concentrations (above the stipulated levels) of chromium in blood, urine and some body tissues, with inhalation being the main route. Health and Safety Executive (HSE), UK, and American Conference of Governmental Industrial Hygienist (ACGIH) and National Institute for Occupational Safety and Health (NIOSH), USA stipulates an occupational exposure limit of 0.5 mg Cr/m3 (8 h TWA) for total chromium. However, schedule 1 of Controls of substances hazardous to health (COSHH) regulations developed by HSE, indicate 0.05 mg m3 (8 h TWA reference periods) to be the limit for Cr (VI) exposure. The exposure limit for individual (e.g., Cr, Zn, Ni etc.) contaminants (homogeneity) was not exceeded, but potential impact of heterogeneity (multi-element synergistic effect) on toxicity requires application of the precautionary principle."
1079444,Huang et al. 2008,Systemic inflammation caused by white smoke inhalation in a combat exercise,"<strong>BACKGROUND: </strong>White smoke inhalation is an uncommon but potentially deadly cause of acute lung injury. No clinical spectrum or treatment protocol have been developed.<br /><br /><strong>METHODS: </strong>Twenty patients accidentally been exposed to white smoke during military training were the subjects of this study. We analyzed clinical manifestations, cytokine changes, and treatment outcomes.<br /><br /><strong>RESULTS: </strong>All patients initially presented with fever, dry cough, chest tightness, and shortness of breath. Twenty-five percent of these patients had severe acute lung injury requiring artificial ventilation support. Elevation of serum tumor necrosis factor-alpha was observed before treatment with antibiotics and glucocorticoids, but the elevation of transforming growth factor-beta(1) was delayed for 2 to 4 weeks after the accident. All the patients had leukocytosis, which correlated positively to disease severity and negatively to intensive treatments. Ninety-five percent of patients had varying degrees of restrictive ventilation impairment, and 85% of these patients had a significantly reduced diffusion capacity in the lungs. Seventy percent of these patients had transient impairment of liver function, which did not correlate to disease severity. The respiratory sequela of restrictive ventilation impairment developed in the most severely affected patients, whereas other tissue toxicities were mostly transient. Treatment included glucocorticoids, antibiotics, and respiratory therapy. All of the patients survived.<br /><br /><strong>CONCLUSION: </strong>A proper ventilation strategy, early pharmacologic therapy including glucocorticoids, and complication prevention may contribute to good treatment outcomes after white smoke inhalation.","Systemic inflammation caused by white smoke inhalation in a combat exercise Abs: <strong>BACKGROUND: </strong>White smoke inhalation is an uncommon but potentially deadly cause of acute lung injury. No clinical spectrum or treatment protocol have been developed.<br /><br /><strong>METHODS: </strong>Twenty patients accidentally been exposed to white smoke during military training were the subjects of this study. We analyzed clinical manifestations, cytokine changes, and treatment outcomes.<br /><br /><strong>RESULTS: </strong>All patients initially presented with fever, dry cough, chest tightness, and shortness of breath. Twenty-five percent of these patients had severe acute lung injury requiring artificial ventilation support. Elevation of serum tumor necrosis factor-alpha was observed before treatment with antibiotics and glucocorticoids, but the elevation of transforming growth factor-beta(1) was delayed for 2 to 4 weeks after the accident. All the patients had leukocytosis, which correlated positively to disease severity and negatively to intensive treatments. Ninety-five percent of patients had varying degrees of restrictive ventilation impairment, and 85% of these patients had a significantly reduced diffusion capacity in the lungs. Seventy percent of these patients had transient impairment of liver function, which did not correlate to disease severity. The respiratory sequela of restrictive ventilation impairment developed in the most severely affected patients, whereas other tissue toxicities were mostly transient. Treatment included glucocorticoids, antibiotics, and respiratory therapy. All of the patients survived.<br /><br /><strong>CONCLUSION: </strong>A proper ventilation strategy, early pharmacologic therapy including glucocorticoids, and complication prevention may contribute to good treatment outcomes after white smoke inhalation."
1079413,Scott and  Proctor 2008,Soil suspension/dispersion modeling methods for estimating health-based soil cleanup levels of hexavalent chromium at chromite ore processing residue sites,"The primary health concern associated with exposures to chromite ore processing residue (COPR)-affected soils is inhalation of hexavalent chromium [Cr(VI)] particulates. Site-specific soil alternative remediation standards (ARSs) are set using soil suspension and dispersion models to be protective of the theoretical excess cancer risk associated with inhalation of soil suspended by vehicle traffic and wind. The purpose of this study was to update a previous model comparison study that identified the 1995 AP-42 particulate emission model for vehicle traffic over unpaved roads and the Fugitive Dust Model (FDM) as the most appropriate model combination for estimating site-specific ARSs. Because the AP-42 model has been revised, we have updated our past evaluation. Specifically, the 2006 AP-42 particulate emissions model; the Industrial Source Complex-Short Term model, version 3 (ISCST3); and the American Meteorological Society/Environmental Protection Agency Regulatory Model (AERMOD) air dispersion models were evaluated, and the results were compared with those from the previously used modeling approaches. Two sites with and two sites without vehicle traffic were evaluated to determine if wind erosion is a significant source of emissions. For the two sites with vehicle traffic, both FDM and ISCST3 produced total suspended particulate (TSP) estimates that were, on average, within a factor of 2 of measured; whereas AERMOD produced estimates that were as much as 5-fold higher than measured. In general, the estimated TSP concentrations for FDM were higher than those for ISCST3. For airborne Cr(VI), the ISCST3 model produced estimates that were only 2- to 8-fold of the measured concentrations, and both FDM and AERMOD estimated airborne Cr(VI) concentrations that were approximately 4- to 14-fold higher than measured. Results using the 1995 AP-42 model were closer to measured than those from the 2006 AP-42 model. Wind erosion was an insignificant contributor to particulate emissions at COPR sites.","Soil suspension/dispersion modeling methods for estimating health-based soil cleanup levels of hexavalent chromium at chromite ore processing residue sites Abs: The primary health concern associated with exposures to chromite ore processing residue (COPR)-affected soils is inhalation of hexavalent chromium [Cr(VI)] particulates. Site-specific soil alternative remediation standards (ARSs) are set using soil suspension and dispersion models to be protective of the theoretical excess cancer risk associated with inhalation of soil suspended by vehicle traffic and wind. The purpose of this study was to update a previous model comparison study that identified the 1995 AP-42 particulate emission model for vehicle traffic over unpaved roads and the Fugitive Dust Model (FDM) as the most appropriate model combination for estimating site-specific ARSs. Because the AP-42 model has been revised, we have updated our past evaluation. Specifically, the 2006 AP-42 particulate emissions model; the Industrial Source Complex-Short Term model, version 3 (ISCST3); and the American Meteorological Society/Environmental Protection Agency Regulatory Model (AERMOD) air dispersion models were evaluated, and the results were compared with those from the previously used modeling approaches. Two sites with and two sites without vehicle traffic were evaluated to determine if wind erosion is a significant source of emissions. For the two sites with vehicle traffic, both FDM and ISCST3 produced total suspended particulate (TSP) estimates that were, on average, within a factor of 2 of measured; whereas AERMOD produced estimates that were as much as 5-fold higher than measured. In general, the estimated TSP concentrations for FDM were higher than those for ISCST3. For airborne Cr(VI), the ISCST3 model produced estimates that were only 2- to 8-fold of the measured concentrations, and both FDM and AERMOD estimated airborne Cr(VI) concentrations that were approximately 4- to 14-fold higher than measured. Results using the 1995 AP-42 model were closer to measured than those from the 2006 AP-42 model. Wind erosion was an insignificant contributor to particulate emissions at COPR sites."
1076245,Chang et al. 2011,Hexavalent chromium inhibited the expression of RKIP of heart in vivo and in vitro,"<strong>BACKGROUND: </strong>Chromium (Cr) is considered to be a risk factor to the cardiovascular effects of fine particulate matter components to PM2.5 from traffic in highway patrol officers. RKIP (raf kinase inhibitor protein) is a physiological inhibitor of GRK-2 (G-protein-coupled receptor kinase 2) and affects ?-adrenergic signaling and contractile activity in cardiomyocytes.<br /><br /><strong>OBJECTIVES: </strong>In this study, we explored the change of RKIP in heart of chromium (VI)-exposed rats and cultured myocardial cells with chromium (VI) treatment.<br /><br /><strong>METHOD: </strong>Wistar rats were divided into six groups which were chronically fed with 250, 500, 750, 1000, and 1250 ppm Na(2)Cr(2)O(7) and water for 60 days, respectively. Na(2)Cr(2)O(7) dose of 0.25, 0.5, 1.5, 3, 4.5, and 0 ppm (control group) was applied in cultured myocardial cells. The level of heart Cr (VI) was determined by electrothermal atomic absorption spectrometry. The expression of RKIP was measured by Western blot method. The MTT assay was used to measure the toxicity of myocardial cells with Cr (VI) treatment. The apoptosis test of myocardial cells was determined by caspase-3 colorimetric assay kit.<br /><br /><strong>RESULT: </strong>The result showed that the expression of RKIP in heart (in vivo) and myocardial cells (in vitro) was decreased following Cr (VI) dose-dependent treatment.<br /><br /><strong>CONCLUSION: </strong>We suggested that the decrement of RKIP of heart and myocardial cells with Cr (VI) treatment resulted in the function of cardiovascular system decreased.","Hexavalent chromium inhibited the expression of RKIP of heart in vivo and in vitro Abs: <strong>BACKGROUND: </strong>Chromium (Cr) is considered to be a risk factor to the cardiovascular effects of fine particulate matter components to PM2.5 from traffic in highway patrol officers. RKIP (raf kinase inhibitor protein) is a physiological inhibitor of GRK-2 (G-protein-coupled receptor kinase 2) and affects ?-adrenergic signaling and contractile activity in cardiomyocytes.<br /><br /><strong>OBJECTIVES: </strong>In this study, we explored the change of RKIP in heart of chromium (VI)-exposed rats and cultured myocardial cells with chromium (VI) treatment.<br /><br /><strong>METHOD: </strong>Wistar rats were divided into six groups which were chronically fed with 250, 500, 750, 1000, and 1250 ppm Na(2)Cr(2)O(7) and water for 60 days, respectively. Na(2)Cr(2)O(7) dose of 0.25, 0.5, 1.5, 3, 4.5, and 0 ppm (control group) was applied in cultured myocardial cells. The level of heart Cr (VI) was determined by electrothermal atomic absorption spectrometry. The expression of RKIP was measured by Western blot method. The MTT assay was used to measure the toxicity of myocardial cells with Cr (VI) treatment. The apoptosis test of myocardial cells was determined by caspase-3 colorimetric assay kit.<br /><br /><strong>RESULT: </strong>The result showed that the expression of RKIP in heart (in vivo) and myocardial cells (in vitro) was decreased following Cr (VI) dose-dependent treatment.<br /><br /><strong>CONCLUSION: </strong>We suggested that the decrement of RKIP of heart and myocardial cells with Cr (VI) treatment resulted in the function of cardiovascular system decreased."
1074318,Leonard et al. 2004,PbCrO4 mediates cellular responses via reactive oxygen species,"Exposure to certain particulate hexavalent chromium [Cr(VI)] compounds, such as lead chromate (PbCrO4), has been associated with lung cancer and respiratory tract toxicity. Previous studies indicate that the solubility of Cr(VI)-compounds is an important factor in Cr(VI)-induced carcinogenesis. The present study investigates reactive oxygen species (ROS) generation by PbCrO4 particles and cellular responses using RAW 264.7 cells. A mixture containing PbCrO4 and RAW 264.7 cells generated hydroxyl radical ((.)OH), using cellularly generated H2O2 as a precursor, as measured by electron spin resonance (ESR) spin trapping in combination with H2O2 and (.)OH scavengers, catalase and sodium formate. The effect of ascorbic acid on (.)OH radicals was also measured using ESR. Confocal microscopy showed that particles could become either bound to the cell surface or engulfed over a 120 min time period. H2O2 generation and O2 consumption were also increased after treatment of the cells with PbCrO4. Both NF-kappaB and AP-1 were activated after exposure to PbCrO4 particles as measured by the NF-kappaB or AP-1 luciferase reporter plasmid assay. Our investigation thus demonstrated that the RAW 264.7 cells phagocytized the PbCrO4 particles leading to accumulation of the particles within vacuoles in the cytoplasm. These particles could induce chronic production of ROS and activation of NF-kappaB and AP-1. Such induction of transcription pathways may be involved in the inflammatory and carcinogenic responses induced by Cr(VI)-containing particles.","PbCrO4 mediates cellular responses via reactive oxygen species Abs: Exposure to certain particulate hexavalent chromium [Cr(VI)] compounds, such as lead chromate (PbCrO4), has been associated with lung cancer and respiratory tract toxicity. Previous studies indicate that the solubility of Cr(VI)-compounds is an important factor in Cr(VI)-induced carcinogenesis. The present study investigates reactive oxygen species (ROS) generation by PbCrO4 particles and cellular responses using RAW 264.7 cells. A mixture containing PbCrO4 and RAW 264.7 cells generated hydroxyl radical ((.)OH), using cellularly generated H2O2 as a precursor, as measured by electron spin resonance (ESR) spin trapping in combination with H2O2 and (.)OH scavengers, catalase and sodium formate. The effect of ascorbic acid on (.)OH radicals was also measured using ESR. Confocal microscopy showed that particles could become either bound to the cell surface or engulfed over a 120 min time period. H2O2 generation and O2 consumption were also increased after treatment of the cells with PbCrO4. Both NF-kappaB and AP-1 were activated after exposure to PbCrO4 particles as measured by the NF-kappaB or AP-1 luciferase reporter plasmid assay. Our investigation thus demonstrated that the RAW 264.7 cells phagocytized the PbCrO4 particles leading to accumulation of the particles within vacuoles in the cytoplasm. These particles could induce chronic production of ROS and activation of NF-kappaB and AP-1. Such induction of transcription pathways may be involved in the inflammatory and carcinogenic responses induced by Cr(VI)-containing particles."
1072566,Cheng et al. 2011,Time trends of contact allergy to a modified European baseline series in Beijing between 2001 and 2006,"<strong>BACKGROUND: </strong>Monitoring trends of sensitivity rates in a population is useful for epidemiological surveillance. The time trends for sensitivity rates of allergens have not previously been reported in China.<br /><br /><strong>OBJECTIVES: </strong>The aim of the present study was to determine the prevalence and trends of contact allergy in patients with suspected allergic contact dermatitis in Beijing, China.<br /><br /><strong>PATIENTS/METHODS: </strong>A retrospective analysis of all patch test data from our database was performed. A total of 1354 patients with suspected allergic contact dermatitis between 2001 and 2006 were studied. Patch tests with 20 allergens or mixtures of allergens were performed and analysed.<br /><br /><strong>RESULTS: </strong>Sensitivity to potassium dichromate (50.1%) was most frequent, and sensitivity to imidazolidinyl urea (3.0%) was least frequent. Increasing trends in sensitivity rates for 10 allergens with significant linear regression were observed (p &lt; 0.05), including mercapto mix, black rubber mix, potassium dichromate, formaldehyde, epoxy resin, benzocaine, ethylenediamine dihydrochloride, paraben mix, tixocortol-21-pivalate, and sesquiterpene lactone mix. Sensitivity rates for the other 10 allergens remained stable or showed only a trend (fragrance mix) towards an increase (p(trend) &gt; 0.05).<br /><br /><strong>CONCLUSIONS: </strong>High sensitivity rates were observed in the study. Significant increasing trends in sensitivity rates for 10 allergens, probably reflecting increasing changes in exposure, were found.","Time trends of contact allergy to a modified European baseline series in Beijing between 2001 and 2006 Abs: <strong>BACKGROUND: </strong>Monitoring trends of sensitivity rates in a population is useful for epidemiological surveillance. The time trends for sensitivity rates of allergens have not previously been reported in China.<br /><br /><strong>OBJECTIVES: </strong>The aim of the present study was to determine the prevalence and trends of contact allergy in patients with suspected allergic contact dermatitis in Beijing, China.<br /><br /><strong>PATIENTS/METHODS: </strong>A retrospective analysis of all patch test data from our database was performed. A total of 1354 patients with suspected allergic contact dermatitis between 2001 and 2006 were studied. Patch tests with 20 allergens or mixtures of allergens were performed and analysed.<br /><br /><strong>RESULTS: </strong>Sensitivity to potassium dichromate (50.1%) was most frequent, and sensitivity to imidazolidinyl urea (3.0%) was least frequent. Increasing trends in sensitivity rates for 10 allergens with significant linear regression were observed (p &lt; 0.05), including mercapto mix, black rubber mix, potassium dichromate, formaldehyde, epoxy resin, benzocaine, ethylenediamine dihydrochloride, paraben mix, tixocortol-21-pivalate, and sesquiterpene lactone mix. Sensitivity rates for the other 10 allergens remained stable or showed only a trend (fragrance mix) towards an increase (p(trend) &gt; 0.05).<br /><br /><strong>CONCLUSIONS: </strong>High sensitivity rates were observed in the study. Significant increasing trends in sensitivity rates for 10 allergens, probably reflecting increasing changes in exposure, were found."
1071208,Xu et al. 2006,Simultaneous decontamination of hexavalent chromium and methyl tert-butyl ether by UV/TiO2 process,"Hexavalent chromium and methyl tert-butyl ether (MTBE) are two important environmental pollutants. Simultaneous decontamination of Cr(VI) and MTBE was studied by UV/TiO2 process. The influences of pH and the concentrations of pollutants on the kinetics of the photocatalytic reactions were evaluated. Dark adsorption tests showed that the acidic pH favored the adsorption of Cr(VI) while neutral pH favored the adsorption of MTBE. Under UV irradiation, Cr(VI) reduction was observed in Cr(VI)/TiO2 system, and MTBE oxidation was observed in MTBE/TiO2 system. The system containing Cr(VI) and MTBE by UV/TiO2 process demonstrated the synergistic effect between oxidation of MTBE and reduction of Cr(VI). The results demonstrated that two pollutants Cr(VI) and MTBE could be eliminated simultaneously by UV/TiO2 process. tert-Butyl formate, tert-butyl alcohol and acetone were identified as primary degradation products of MTBE by gas chromatography-mass spectrometry in the degradation of MTBE by UV/TiO2 process.","Simultaneous decontamination of hexavalent chromium and methyl tert-butyl ether by UV/TiO2 process Abs: Hexavalent chromium and methyl tert-butyl ether (MTBE) are two important environmental pollutants. Simultaneous decontamination of Cr(VI) and MTBE was studied by UV/TiO2 process. The influences of pH and the concentrations of pollutants on the kinetics of the photocatalytic reactions were evaluated. Dark adsorption tests showed that the acidic pH favored the adsorption of Cr(VI) while neutral pH favored the adsorption of MTBE. Under UV irradiation, Cr(VI) reduction was observed in Cr(VI)/TiO2 system, and MTBE oxidation was observed in MTBE/TiO2 system. The system containing Cr(VI) and MTBE by UV/TiO2 process demonstrated the synergistic effect between oxidation of MTBE and reduction of Cr(VI). The results demonstrated that two pollutants Cr(VI) and MTBE could be eliminated simultaneously by UV/TiO2 process. tert-Butyl formate, tert-butyl alcohol and acetone were identified as primary degradation products of MTBE by gas chromatography-mass spectrometry in the degradation of MTBE by UV/TiO2 process."
1071179,Samaratunga et al. 2005,Toluene/ter-butanol mixed solvent for the selective extraction of Cr(VI) from divalent heavy metals,"A solvent-extraction system comprising toluene/ter-butanol (ter-BuOH) mixed solvent as the organic phase was developed to selectively extract Cr(VI) from acidic chloride media in the presence of divalent metals, namely Cd(II), Co(II), Cu(II), Ni(II) and Zn(II) under 5 M CaCl2 salting-out conditions. Chromium(VI) was selectively extracted as a solvated ion-pair of [ter-BuOH2+ x CrO3Cl-] at ter-BuOH mole fractions of between 0.1 and 0.6 (9.0-57.2% in volume). Divalent metals were extracted at ter-BuOH mole fraction over 0.6 with extraction percents of Co (&lt; 20%), Cu (&lt; 15%), Ni (&lt; 10%) and Zn (&lt; 20%). The concentrations of Ca2+, water and ter-BuOH in the organic phase and ter-BuOH in the aqueous phase were determined to find out the effects on the extraction of Cr(VI). The chemical species of Cr(VI) in acidic chloride media containing 5 M CaCl2 and 0.1 M HCl was confirmed to be the CrO3Cl- species. The effects of the acid, salt concentrations in the aqueous phase and the solvent composition of a mixed organic solvent on the extraction of Cr(VI) were evaluated. Based on the above studies, the extraction mechanism was elucidated and the optimum extraction conditions were determined.","Toluene/ter-butanol mixed solvent for the selective extraction of Cr(VI) from divalent heavy metals Abs: A solvent-extraction system comprising toluene/ter-butanol (ter-BuOH) mixed solvent as the organic phase was developed to selectively extract Cr(VI) from acidic chloride media in the presence of divalent metals, namely Cd(II), Co(II), Cu(II), Ni(II) and Zn(II) under 5 M CaCl2 salting-out conditions. Chromium(VI) was selectively extracted as a solvated ion-pair of [ter-BuOH2+ x CrO3Cl-] at ter-BuOH mole fractions of between 0.1 and 0.6 (9.0-57.2% in volume). Divalent metals were extracted at ter-BuOH mole fraction over 0.6 with extraction percents of Co (&lt; 20%), Cu (&lt; 15%), Ni (&lt; 10%) and Zn (&lt; 20%). The concentrations of Ca2+, water and ter-BuOH in the organic phase and ter-BuOH in the aqueous phase were determined to find out the effects on the extraction of Cr(VI). The chemical species of Cr(VI) in acidic chloride media containing 5 M CaCl2 and 0.1 M HCl was confirmed to be the CrO3Cl- species. The effects of the acid, salt concentrations in the aqueous phase and the solvent composition of a mixed organic solvent on the extraction of Cr(VI) were evaluated. Based on the above studies, the extraction mechanism was elucidated and the optimum extraction conditions were determined."
1071090,Fong et al. 2007,Determination of mercury in whole blood and urine by inductively coupled plasma mass spectrometry,"The conventional method for the determination of mercury in clinical samples is cold vapor atomic absorption spectrometry. Sample digestion or pretreatment require large sample volume and long sample preparation time. The inductively coupled plasma mass spectrometry (ICP-MS) method developed in this study requires only 100 microL of sample with practically no preparation, except for dilution with diluent. Significant savings in sample volumes, reagents, technician time, and analysis time are realized. Among different types of diluents, the one containing acid, tert-butanol, and potassium dichromate gave the best results to remove the mercury memory effect. The interassay precisions for whole blood and urine were &lt; 5% and &lt; 8%, respectively, and the intra-assay precisions were &lt; 3% and &lt; 7%, respectively. The lower limits of detection were 0.13, 0.17, and 0.26 microg/L for aqueous standard, urine, and whole blood, respectively. The developed ICP-MS method correlated well with the atomic absorption method and can offer an alternative to the atomic absorption method for mercury analysis with less sample volume requirement as well as shorter analysis time.","Determination of mercury in whole blood and urine by inductively coupled plasma mass spectrometry Abs: The conventional method for the determination of mercury in clinical samples is cold vapor atomic absorption spectrometry. Sample digestion or pretreatment require large sample volume and long sample preparation time. The inductively coupled plasma mass spectrometry (ICP-MS) method developed in this study requires only 100 microL of sample with practically no preparation, except for dilution with diluent. Significant savings in sample volumes, reagents, technician time, and analysis time are realized. Among different types of diluents, the one containing acid, tert-butanol, and potassium dichromate gave the best results to remove the mercury memory effect. The interassay precisions for whole blood and urine were &lt; 5% and &lt; 8%, respectively, and the intra-assay precisions were &lt; 3% and &lt; 7%, respectively. The lower limits of detection were 0.13, 0.17, and 0.26 microg/L for aqueous standard, urine, and whole blood, respectively. The developed ICP-MS method correlated well with the atomic absorption method and can offer an alternative to the atomic absorption method for mercury analysis with less sample volume requirement as well as shorter analysis time."
1070702,Beveridge et al. 2010,"Lung cancer risk associated with occupational exposure to nickel, chromium VI, and cadmium in two population-based case-control studies in Montreal","<strong>BACKGROUND: </strong>Nickel, chromium VI, and cadmium have been identified as lung carcinogens in highly exposed cohorts. The purpose of this study was to examine the etiological link between lung cancer and these metals in occupations, that usually entail lower levels of exposure than those seen in historical cohorts.<br /><br /><strong>METHODS: </strong>Two population-based case-control studies were conducted in Montreal, from 1979 to 1986 and from 1996 to 2001, comprising 1,598 cases and 1,965 controls. A detailed job history was obtained to evaluate lifetime occupational exposure to many agents, including nickel, chromium VI, and cadmium compounds.<br /><br /><strong>RESULTS: </strong>Lung cancer odds ratios were increased only among former or non-smokers: 2.5 (95% CI: 1.3-4.7) for nickel exposure, 2.4 (95% CI: 1.2-4.8) for chromium VI, and 4.7 (95% CI: 1.5-14.3) for cadmium. The metals did not increase risk among smokers.<br /><br /><strong>CONCLUSIONS: </strong>While excess risks due to these metal compounds were barely discernable among smokers, carcinogenic effects were seen among non-smokers.","Lung cancer risk associated with occupational exposure to nickel, chromium VI, and cadmium in two population-based case-control studies in Montreal Abs: <strong>BACKGROUND: </strong>Nickel, chromium VI, and cadmium have been identified as lung carcinogens in highly exposed cohorts. The purpose of this study was to examine the etiological link between lung cancer and these metals in occupations, that usually entail lower levels of exposure than those seen in historical cohorts.<br /><br /><strong>METHODS: </strong>Two population-based case-control studies were conducted in Montreal, from 1979 to 1986 and from 1996 to 2001, comprising 1,598 cases and 1,965 controls. A detailed job history was obtained to evaluate lifetime occupational exposure to many agents, including nickel, chromium VI, and cadmium compounds.<br /><br /><strong>RESULTS: </strong>Lung cancer odds ratios were increased only among former or non-smokers: 2.5 (95% CI: 1.3-4.7) for nickel exposure, 2.4 (95% CI: 1.2-4.8) for chromium VI, and 4.7 (95% CI: 1.5-14.3) for cadmium. The metals did not increase risk among smokers.<br /><br /><strong>CONCLUSIONS: </strong>While excess risks due to these metal compounds were barely discernable among smokers, carcinogenic effects were seen among non-smokers."
1070452,Chervona et al. ,"Carcinogenic metals and the epigenome: understanding the effect of nickel, arsenic, and chromium","Carcinogenic metals, such as nickel, arsenic, and chromium, are widespread environmental and occupational pollutants. Chronic exposure to these metals has been connected with increased risks of numerous cancers and as well as non-carcinogenic health outcomes, including cardiovascular disease, neurologic deficits, neuro-developmental deficits in childhood, and hypertension. However, currently the specific molecular targets for metal toxicity and carcinogenicity are not fully understood. Here, we propose that the iron- and 2-oxoglutarate-dependent dioxygenase family enzymes, as well as, other histone modifying enzymes are important intracellular targets that mediate the toxicity and carcinogenicity of nickel, and maybe potential targets in chromium and arsenic induced carcinogenesis. Our data demonstrate that all three metals are capable of inducing post-translational histone modifications and affecting the enzymes that modulate them (i.e. the iron- and 2-oxoglutarate-dependent dioxygenase family, including HIF-prolyl hydroxylase PHD2, histone demethylase JHDM2A/JMJD1A, and DNA repair enzymes ABH3 and ABH2, and histone methyltransferases, G9a). Given the effects that these metals can exert on the epigenome, future studies of their involvement in histone modifying enzymes dynamics would deepen our understanding on their respective toxicities and carcinogenicities.","Carcinogenic metals and the epigenome: understanding the effect of nickel, arsenic, and chromium Abs: Carcinogenic metals, such as nickel, arsenic, and chromium, are widespread environmental and occupational pollutants. Chronic exposure to these metals has been connected with increased risks of numerous cancers and as well as non-carcinogenic health outcomes, including cardiovascular disease, neurologic deficits, neuro-developmental deficits in childhood, and hypertension. However, currently the specific molecular targets for metal toxicity and carcinogenicity are not fully understood. Here, we propose that the iron- and 2-oxoglutarate-dependent dioxygenase family enzymes, as well as, other histone modifying enzymes are important intracellular targets that mediate the toxicity and carcinogenicity of nickel, and maybe potential targets in chromium and arsenic induced carcinogenesis. Our data demonstrate that all three metals are capable of inducing post-translational histone modifications and affecting the enzymes that modulate them (i.e. the iron- and 2-oxoglutarate-dependent dioxygenase family, including HIF-prolyl hydroxylase PHD2, histone demethylase JHDM2A/JMJD1A, and DNA repair enzymes ABH3 and ABH2, and histone methyltransferases, G9a). Given the effects that these metals can exert on the epigenome, future studies of their involvement in histone modifying enzymes dynamics would deepen our understanding on their respective toxicities and carcinogenicities."
1070401,Landrot et al. ,Arsenic and chromium speciation in an urban contaminated soil,"The distribution and speciation of As and Cr in a contaminated soil were studied by synchrotron-based X-ray microfluorescence (?-XRF), microfocused X-ray absorption spectroscopy (?-XAS), and bulk extended X-ray absorption fine structure spectroscopy (EXAFS). The soil was taken from a park in Wilmington, DE, which had been an important center for the leather tanning industry along the Atlantic seaboard of the United States, until the early 20th century. Soil concentrations of As, Cr, and Pb measured at certain locations in the park greatly exceeded the background levels of these heavy metals in the State of Delaware. Results show that Cr(III) and As(V) species are mainly present in the soil, with insignificant amounts of Cr(VI) and As(III). Micro-XRF maps show that Cr and Fe are distributed together in regions where their concentrations are diffuse, and at local spots where their concentrations are high. Iron oxides, which can reduce Cr(VI) to Cr(III), are present at some of these hot spots where Cr and Fe are highly concentrated. Arsenic is mainly associated with Al in the soil, and to a minor extent with Fe. Arsenate may be sorbed to aluminum oxides, which might have transformed after a long period of time into an As-Al precipitate phase, having a structure and chemical composition similar to mansfieldite (AlAsO(4)?2H(2)O). The latter hypothesis is supported by the fact that only a small amount of As present in the soil was desorbed using the characteristic toxicity leaching procedure tests. This suggests that As is immobilized in the soil.","Arsenic and chromium speciation in an urban contaminated soil Abs: The distribution and speciation of As and Cr in a contaminated soil were studied by synchrotron-based X-ray microfluorescence (?-XRF), microfocused X-ray absorption spectroscopy (?-XAS), and bulk extended X-ray absorption fine structure spectroscopy (EXAFS). The soil was taken from a park in Wilmington, DE, which had been an important center for the leather tanning industry along the Atlantic seaboard of the United States, until the early 20th century. Soil concentrations of As, Cr, and Pb measured at certain locations in the park greatly exceeded the background levels of these heavy metals in the State of Delaware. Results show that Cr(III) and As(V) species are mainly present in the soil, with insignificant amounts of Cr(VI) and As(III). Micro-XRF maps show that Cr and Fe are distributed together in regions where their concentrations are diffuse, and at local spots where their concentrations are high. Iron oxides, which can reduce Cr(VI) to Cr(III), are present at some of these hot spots where Cr and Fe are highly concentrated. Arsenic is mainly associated with Al in the soil, and to a minor extent with Fe. Arsenate may be sorbed to aluminum oxides, which might have transformed after a long period of time into an As-Al precipitate phase, having a structure and chemical composition similar to mansfieldite (AlAsO(4)?2H(2)O). The latter hypothesis is supported by the fact that only a small amount of As present in the soil was desorbed using the characteristic toxicity leaching procedure tests. This suggests that As is immobilized in the soil."
1070358,Wang et al. 2012,Arsenic and chromium in drinking water promote tumorigenesis in a mouse colitis-associated colorectal cancer model and the potential mechanism is ROS-mediated Wnt/?-catenin signaling pathway,"Exposure to carcinogenic metals, such as trivalent arsenic [As(III)] and hexavalent chromium [Cr(VI)], through drinking water is a major global public health problem and is associated with various cancers. However, the mechanism of their carcinogenicity remains unclear. In this study, we used azoxymethane/dextran sodium sulfate (AOM/DSS)-induced mouse colitis-associated colorectal cancer model to investigate their tumorigenesis. Our results demonstrate that exposure to As(III) or Cr(VI), alone or in combination, together with AOM/DSS pretreatment has a promotion effect, increasing the colorectal tumor incidence, multiplicity, size, and grade, as well as cell inflammatory response. Two-dimensional differential gel electrophoresis coupled with mass spectrometry revealed that As(III) or Cr(VI) treatment alone significantly changed the density of proteins. The expression of ?-catenin and phospho-GSK was increased by treatment of carcinogenic metals alone. Concomitantly, the expression of NADPH oxidase1 (NOX1) and the level of 8-OHdG were also increased by treatment of carcinogenic metals alone. Antioxidant enzymes, such as superoxide dismutase (SOD) and catalase, were decreased. Similarly, in an in vitro system, exposure of CRL-1807 to carcinogenic metals increased reactive oxygen species (ROS) generation, the expression of ?-catenin, phospho-GSK, and NOX1. Inhibition of ROS generation by addition of SOD or catalase inhibited ?-catenin expression and activity. Our study provides a new animal model to study the carcinogenicity of As(III) and Cr(VI) and suggests that As(III) and Cr(VI) promote colorectal cancer tumorigenesis, at least partly, through ROS-mediated Wnt/?-catenin signaling pathway.","Arsenic and chromium in drinking water promote tumorigenesis in a mouse colitis-associated colorectal cancer model and the potential mechanism is ROS-mediated Wnt/?-catenin signaling pathway Abs: Exposure to carcinogenic metals, such as trivalent arsenic [As(III)] and hexavalent chromium [Cr(VI)], through drinking water is a major global public health problem and is associated with various cancers. However, the mechanism of their carcinogenicity remains unclear. In this study, we used azoxymethane/dextran sodium sulfate (AOM/DSS)-induced mouse colitis-associated colorectal cancer model to investigate their tumorigenesis. Our results demonstrate that exposure to As(III) or Cr(VI), alone or in combination, together with AOM/DSS pretreatment has a promotion effect, increasing the colorectal tumor incidence, multiplicity, size, and grade, as well as cell inflammatory response. Two-dimensional differential gel electrophoresis coupled with mass spectrometry revealed that As(III) or Cr(VI) treatment alone significantly changed the density of proteins. The expression of ?-catenin and phospho-GSK was increased by treatment of carcinogenic metals alone. Concomitantly, the expression of NADPH oxidase1 (NOX1) and the level of 8-OHdG were also increased by treatment of carcinogenic metals alone. Antioxidant enzymes, such as superoxide dismutase (SOD) and catalase, were decreased. Similarly, in an in vitro system, exposure of CRL-1807 to carcinogenic metals increased reactive oxygen species (ROS) generation, the expression of ?-catenin, phospho-GSK, and NOX1. Inhibition of ROS generation by addition of SOD or catalase inhibited ?-catenin expression and activity. Our study provides a new animal model to study the carcinogenicity of As(III) and Cr(VI) and suggests that As(III) and Cr(VI) promote colorectal cancer tumorigenesis, at least partly, through ROS-mediated Wnt/?-catenin signaling pathway."
1070155,Mitchell et al. 1988,Evaluation of the L5178Y mouse lymphoma cell mutagenesis assay: Intralaboratory results for sixty-three coded chemicals tested at sri international,,Evaluation of the L5178Y mouse lymphoma cell mutagenesis assay: Intralaboratory results for sixty-three coded chemicals tested at sri international Abs: 
1069076,WORK 1992,OCCUPATIONAL TOXICANTS VOL. 3,BIOSIS COPYRIGHT: BIOL ABS. RRM BOOK HUMAN ANIMAL ACETALDEHYDE ACRYLAMIDE BERYLLIUM O CHLOROANILINE M CHLOROANILINE P CHLOROANILINE CHLORODIFLUOROMETHANE COBALT CHLOROETHANE CHLOROPARAFFIN CHROMIUM 3 3' DIAMINOBENZIDINE 1 2 DICHLOROETHANE N N DIMETHYLANILINE DMSO FORMALDEHYDE LITHIUM HYDRIDE METHYL METHACRYLATE NITRIC ACID 2 NITROPROPANE ORGANIC PEROXIDES PENTACHLOROPHENOL TETRACHLOROPHENOL TETRAETHYL SILICATE O TOLUIDINE O TOLUIDINE HYDROCHLORIDE P TOLUIDINE TRICHLOROBENZENE 1 1 2 TRICHLORO-1 2 2-TRIFLUOROETHANE REPRODUCTIVE TOXICITY DEVELOPMENTAL TOXICITY GENOTOXICITY CARCINOGENICITY TOXICODYNAMICS,OCCUPATIONAL TOXICANTS VOL. 3 Abs: BIOSIS COPYRIGHT: BIOL ABS. RRM BOOK HUMAN ANIMAL ACETALDEHYDE ACRYLAMIDE BERYLLIUM O CHLOROANILINE M CHLOROANILINE P CHLOROANILINE CHLORODIFLUOROMETHANE COBALT CHLOROETHANE CHLOROPARAFFIN CHROMIUM 3 3' DIAMINOBENZIDINE 1 2 DICHLOROETHANE N N DIMETHYLANILINE DMSO FORMALDEHYDE LITHIUM HYDRIDE METHYL METHACRYLATE NITRIC ACID 2 NITROPROPANE ORGANIC PEROXIDES PENTACHLOROPHENOL TETRACHLOROPHENOL TETRAETHYL SILICATE O TOLUIDINE O TOLUIDINE HYDROCHLORIDE P TOLUIDINE TRICHLOROBENZENE 1 1 2 TRICHLORO-1 2 2-TRIFLUOROETHANE REPRODUCTIVE TOXICITY DEVELOPMENTAL TOXICITY GENOTOXICITY CARCINOGENICITY TOXICODYNAMICS
1067641,Aquino and  Stuckey 2004,Soluble microbial products formation in anaerobic chemostats in the presence of toxic compounds,"Anaerobic chemostats fed on glucose (approximately 10 g chemical oxygen demand (COD)/L) were used to investigate the effects of toxicity on soluble microbial product (SMP) formation. Addition of the toxic compounds chloroform and chromium increased the net accumulation of SMP, despite reducing the percentage of SMP in the effluent due to the overwhelming production of volatile fatty acids (VFAs). In the reactor spiked with chloroform the normalized accumulation of SMP (SMP/So) increased from 2% to 8%, whereas in the reactor spiked with Cr (VI) the SMP/So ratio reached as high as 20% after the spike, and in both cases SMP net accumulation was proportional to the concentration of toxicant. After the chloroform and chromium spikes biomass seemed to produce more extra cellular polymeric substances (EPS) suggesting that this might have helped them to cope with the stress. Chromatography results indicate that some of the high MW compounds present in the SMP might have been due to EPS release into the bulk solution, and that other compounds, probably released as a result of cell lysis, were also present. Hydrolysis of EPS did not seem to contribute to SMP accumulation in the presence of toxic compounds, and DNA analysis suggested that cell lysis products was an important contribution to SMP accumulation, in the presence of chromium.","Soluble microbial products formation in anaerobic chemostats in the presence of toxic compounds Abs: Anaerobic chemostats fed on glucose (approximately 10 g chemical oxygen demand (COD)/L) were used to investigate the effects of toxicity on soluble microbial product (SMP) formation. Addition of the toxic compounds chloroform and chromium increased the net accumulation of SMP, despite reducing the percentage of SMP in the effluent due to the overwhelming production of volatile fatty acids (VFAs). In the reactor spiked with chloroform the normalized accumulation of SMP (SMP/So) increased from 2% to 8%, whereas in the reactor spiked with Cr (VI) the SMP/So ratio reached as high as 20% after the spike, and in both cases SMP net accumulation was proportional to the concentration of toxicant. After the chloroform and chromium spikes biomass seemed to produce more extra cellular polymeric substances (EPS) suggesting that this might have helped them to cope with the stress. Chromatography results indicate that some of the high MW compounds present in the SMP might have been due to EPS release into the bulk solution, and that other compounds, probably released as a result of cell lysis, were also present. Hydrolysis of EPS did not seem to contribute to SMP accumulation in the presence of toxic compounds, and DNA analysis suggested that cell lysis products was an important contribution to SMP accumulation, in the presence of chromium."
1066484,Heil and  Reifferscheid 1992,Detection of mammalian carcinogens with an immunological DNA synthesis-inhibition test,"There is a close relationship between genotoxicity, mutagenicity and carcinogenicity. But the controversy of which short-term test system best recognizes human carcinogens is still going on. Currently, the Salmonella gene mutation assay ('Ames test') is the most widely used test for the screening of mutagens. However, many in vitro tests hold unsatisfactory validity data, presumably because of the inability of present short-term tests to detect non-genotoxic carcinogens, which are increasingly being brought into focus in the discussions of genesis of cancer. One principle often neglected in this context is the property of genotoxic agents to inhibit replicative DNA synthesis in (proliferating) eukaryotic cells. We believe that this early response to DNA damage is important in the multistage process of carcinogenesis. Accordingly, we proposed that a DNA synthesis-inhibition test should be included in the test batteries for carcinogen screening. In this paper we report the development of an appropriate DNA synthesis-inhibition test based on immunological techniques.","Detection of mammalian carcinogens with an immunological DNA synthesis-inhibition test Abs: There is a close relationship between genotoxicity, mutagenicity and carcinogenicity. But the controversy of which short-term test system best recognizes human carcinogens is still going on. Currently, the Salmonella gene mutation assay ('Ames test') is the most widely used test for the screening of mutagens. However, many in vitro tests hold unsatisfactory validity data, presumably because of the inability of present short-term tests to detect non-genotoxic carcinogens, which are increasingly being brought into focus in the discussions of genesis of cancer. One principle often neglected in this context is the property of genotoxic agents to inhibit replicative DNA synthesis in (proliferating) eukaryotic cells. We believe that this early response to DNA damage is important in the multistage process of carcinogenesis. Accordingly, we proposed that a DNA synthesis-inhibition test should be included in the test batteries for carcinogen screening. In this paper we report the development of an appropriate DNA synthesis-inhibition test based on immunological techniques."
1066307,Zhou et al. 2001,Catalytic effect of soil colloids on the reaction between CrVI and p-methoxyphenol,"Adsorption of CrVI and p-methoxyphenol (PMP) on soil colloids at different pH media was studied. The resulting k1 and n of 1.89 x 10(2) and 0.53 (r2 = 0.99) and k2 and b of 0.13 and 1.25 x 10(3) (r2 = 0.96) were obtained from Freundlich (Q = k1Caqn) and Langmuir [Q = k2bCaq/(1 + k2Caq)] simulation equations, respectively, for CrVI adsorption on soil colloids (pH 4.20). The adsorption of PMP on soil colloids in pH 5.72 media was simulated by five different equations and the results indicated that the Fritz-Schluender one (r2 = 1.00) was the most suitable among them. Adsorption quantity of CrVI and PMP on colloids increased with increasing acidity in the pH range of 3.5-9.0. Study of CrVI adsorption kinetics indicated that the adsorption equilibrium of CrVI was reached rapidly within 2 h. In pure aqueous solution, CrVI reduction by PMP was observed only when the media's pH was lower than 4.0. Oxidation and reduction reaction between CrVI and p-methoxyphenol obviously occurred when soil colloids were involved in this system, even at pH &gt; or = 7.0, which strongly suggested that minerals in soil colloids acted as catalysts to speed the reaction of CrVI and PMP. The oxidized product of PMP by CrVI, extracted by chloroform in acid media and analyzed by gas chromatography-mass spectrometry, was identified as benzoquinone. The reaction included two steps of one electron process.","Catalytic effect of soil colloids on the reaction between CrVI and p-methoxyphenol Abs: Adsorption of CrVI and p-methoxyphenol (PMP) on soil colloids at different pH media was studied. The resulting k1 and n of 1.89 x 10(2) and 0.53 (r2 = 0.99) and k2 and b of 0.13 and 1.25 x 10(3) (r2 = 0.96) were obtained from Freundlich (Q = k1Caqn) and Langmuir [Q = k2bCaq/(1 + k2Caq)] simulation equations, respectively, for CrVI adsorption on soil colloids (pH 4.20). The adsorption of PMP on soil colloids in pH 5.72 media was simulated by five different equations and the results indicated that the Fritz-Schluender one (r2 = 1.00) was the most suitable among them. Adsorption quantity of CrVI and PMP on colloids increased with increasing acidity in the pH range of 3.5-9.0. Study of CrVI adsorption kinetics indicated that the adsorption equilibrium of CrVI was reached rapidly within 2 h. In pure aqueous solution, CrVI reduction by PMP was observed only when the media's pH was lower than 4.0. Oxidation and reduction reaction between CrVI and p-methoxyphenol obviously occurred when soil colloids were involved in this system, even at pH &gt; or = 7.0, which strongly suggested that minerals in soil colloids acted as catalysts to speed the reaction of CrVI and PMP. The oxidized product of PMP by CrVI, extracted by chloroform in acid media and analyzed by gas chromatography-mass spectrometry, was identified as benzoquinone. The reaction included two steps of one electron process."
1065744,Sullivan 1992,"Cryogenics, oxidizers, reducing agents, and explosives","This chapter reviewed the hazards associated with exposure to cryogenics, oxidizers, reducing agents and explosives. Specific materials discussed under explosives include nitroglycerin (55630), cyclonite (121824), pentaerythritoltetranitrate (78115), 2,4,6-trinitrotoluene (118967), tetryl (479458), and picric-acid (88891). Major oxidizers and oxidizing agents reviewed included hydrogen-peroxide (7722841), benzoyl-peroxide (94360), peracetic-acid (79210), cumene-hydroperoxide (80159), and methyl-ethyl-ketone-peroxide (1338234). Halogenated oxidizers and halogen gases reviewed included perchloryl-fluoride (7616946), oxychlorinated compounds, chlorates, perchlorates, halogen gases, bromine (7726956), chlorine (7782505), fluorine (86737), iodine (7553562), bromine-pentafluoride (7789302), chlorine-trifluoride (7790912), chlorine-dioxide (10049044), oxygen-difluoride (7783417), ammonium-nitrate (6484522), ammonium-nitrite (13446485), and ammonium-picrate (131748). Chromates, chromium metals and chromium salts reviewed included chromic-acid (617129), chromyl-chloride (14977618), ammonium-dichromate (7789095), chromium-trioxide (1333820), permanganates, and potassium-persulfate (7727211). Reactive reducing chemicals reviewed included hydrazine (302012), monomethylhydrazine (60344), hydroxylamine (7803498), decaborane (17702419), pentaborane (19624227), boron-trifluoride (7637072), boron-tribromide (10294334), and lithium-hydride (7580678). Compressed flammable gases and cryogenic gases discussed included liquid hydrogen, liquified oxygen, liquified helium, liquefied natural gas, liquefied ammonia gas, and liquefied petroleum gas. KW - DCN-213184","Cryogenics, oxidizers, reducing agents, and explosives Abs: This chapter reviewed the hazards associated with exposure to cryogenics, oxidizers, reducing agents and explosives. Specific materials discussed under explosives include nitroglycerin (55630), cyclonite (121824), pentaerythritoltetranitrate (78115), 2,4,6-trinitrotoluene (118967), tetryl (479458), and picric-acid (88891). Major oxidizers and oxidizing agents reviewed included hydrogen-peroxide (7722841), benzoyl-peroxide (94360), peracetic-acid (79210), cumene-hydroperoxide (80159), and methyl-ethyl-ketone-peroxide (1338234). Halogenated oxidizers and halogen gases reviewed included perchloryl-fluoride (7616946), oxychlorinated compounds, chlorates, perchlorates, halogen gases, bromine (7726956), chlorine (7782505), fluorine (86737), iodine (7553562), bromine-pentafluoride (7789302), chlorine-trifluoride (7790912), chlorine-dioxide (10049044), oxygen-difluoride (7783417), ammonium-nitrate (6484522), ammonium-nitrite (13446485), and ammonium-picrate (131748). Chromates, chromium metals and chromium salts reviewed included chromic-acid (617129), chromyl-chloride (14977618), ammonium-dichromate (7789095), chromium-trioxide (1333820), permanganates, and potassium-persulfate (7727211). Reactive reducing chemicals reviewed included hydrazine (302012), monomethylhydrazine (60344), hydroxylamine (7803498), decaborane (17702419), pentaborane (19624227), boron-trifluoride (7637072), boron-tribromide (10294334), and lithium-hydride (7580678). Compressed flammable gases and cryogenic gases discussed included liquid hydrogen, liquified oxygen, liquified helium, liquefied natural gas, liquefied ammonia gas, and liquefied petroleum gas. KW - DCN-213184"
1060179,Klein et al. 1994,Metal mutagenesis in transgenic Chinese hamster cell lines,"Metals are toxic agents for which genotoxic effects are often difficult to demonstrate. To study metal mutagenesis, we have used two stable hprt/gpt+ transgenic cell lines that were derived from Chinese hamster V79 cells. Both the G12 and G10 cell lines are known to be very sensitive to clastogens such as X-rays and bleomycin, with the mutagenic response of the integrated xanthine guanine phosphoribosyl transferase (gpt) gene in G10 usually exceeding that of the same gene in the transgenic G12 cells. In studies with carcinogenic insoluble nickel compounds, a high level of mutagenesis was found at the gpt locus of G12 cells but not at the endogenous hypoxanthine phosphoribosyl transferase (hprt) locus of V79 cells. We have since demonstrated the similar recovery of a high frequency of viable G12 mutants with other insoluble nickel salts including nickel oxides (black and green). The relative mutant yield for the insoluble nickel compounds (G12 > G10) is the opposite of that obtained with nonmetal clastogens (G10 > G12). In the G12 cells, nickel mutagenesis may be related to the integration of the gpt sequence into a heterochromatic region of the genome. For some of the insoluble nickel compounds, significant inhibition of both cytotoxicity and mutant yield resulted when the G12 cells were pretreated with vitamin E. In comparison with the nickel studies, the mutagenic responses to chromium compounds in these cell lines were not as dramatic. Mutagenesis of the gpt target could not be demonstrated with other metals such as mercury or vanadium.","Metal mutagenesis in transgenic Chinese hamster cell lines Abs: Metals are toxic agents for which genotoxic effects are often difficult to demonstrate. To study metal mutagenesis, we have used two stable hprt/gpt+ transgenic cell lines that were derived from Chinese hamster V79 cells. Both the G12 and G10 cell lines are known to be very sensitive to clastogens such as X-rays and bleomycin, with the mutagenic response of the integrated xanthine guanine phosphoribosyl transferase (gpt) gene in G10 usually exceeding that of the same gene in the transgenic G12 cells. In studies with carcinogenic insoluble nickel compounds, a high level of mutagenesis was found at the gpt locus of G12 cells but not at the endogenous hypoxanthine phosphoribosyl transferase (hprt) locus of V79 cells. We have since demonstrated the similar recovery of a high frequency of viable G12 mutants with other insoluble nickel salts including nickel oxides (black and green). The relative mutant yield for the insoluble nickel compounds (G12 > G10) is the opposite of that obtained with nonmetal clastogens (G10 > G12). In the G12 cells, nickel mutagenesis may be related to the integration of the gpt sequence into a heterochromatic region of the genome. For some of the insoluble nickel compounds, significant inhibition of both cytotoxicity and mutant yield resulted when the G12 cells were pretreated with vitamin E. In comparison with the nickel studies, the mutagenic responses to chromium compounds in these cell lines were not as dramatic. Mutagenesis of the gpt target could not be demonstrated with other metals such as mercury or vanadium."
1060044,Antonini et al. 1999,Effect of welding fume solubility on lung macrophage viability and function in vitro,"It was shown previously that fumes generated from stainless steel (SS) welding induced more pneumotoxicity and were cleared from the lungs at a slower rate than fumes collected from mild steel (MS) welding. These differences in response may be attributed to the metal composition of SS and MS welding fumes. In this study, fumes with vastly different metal profiles were collected during gas metal arc (GMA) or flux-covered manual metal arc (MMA) welding using two different consumable electrodes, SS or MS. The collected samples were suspended in saline, incubated for 24 h at 37 degrees C, and centrifuged. The supernatant (soluble components) and pellets (insoluble particulates) were separated, and their effects on lung macrophage viability and the release of reactive oxygen species (ROS) by macrophages were examined in vitro. The soluble MMA-SS sample was shown to be the most cytotoxic to macrophages and to have the greatest effect on their function as compared to the GMA-SS and GMA-MS fumes. Neither the soluble nor insoluble forms of the GMA-MS sample had any marked effect on macrophage viability. The flux-covered MMA-SS fume was found to be much more water soluble as compared to either the GMA-SS or the GMA-MS fumes. The soluble fraction of the MMA-SS samples was comprised almost entirely of Cr. The small fraction of the GMA-MS sample that was soluble contained Mn with little Fe, while a more complex mixture was observed in the soluble portion of the GMA-SS sample, which contained Mn, Ni, Fe, Cr, and Cu. Data show that differences in the solubility of welding fumes influence the viability and ROS production of macrophages. The presence of soluble metals, such as Fe, Cr, Ni, Cu, and Mn, and the complexes formed by these different metals are likely important in the pulmonary responses observed after welding fume exposure.","Effect of welding fume solubility on lung macrophage viability and function in vitro Abs: It was shown previously that fumes generated from stainless steel (SS) welding induced more pneumotoxicity and were cleared from the lungs at a slower rate than fumes collected from mild steel (MS) welding. These differences in response may be attributed to the metal composition of SS and MS welding fumes. In this study, fumes with vastly different metal profiles were collected during gas metal arc (GMA) or flux-covered manual metal arc (MMA) welding using two different consumable electrodes, SS or MS. The collected samples were suspended in saline, incubated for 24 h at 37 degrees C, and centrifuged. The supernatant (soluble components) and pellets (insoluble particulates) were separated, and their effects on lung macrophage viability and the release of reactive oxygen species (ROS) by macrophages were examined in vitro. The soluble MMA-SS sample was shown to be the most cytotoxic to macrophages and to have the greatest effect on their function as compared to the GMA-SS and GMA-MS fumes. Neither the soluble nor insoluble forms of the GMA-MS sample had any marked effect on macrophage viability. The flux-covered MMA-SS fume was found to be much more water soluble as compared to either the GMA-SS or the GMA-MS fumes. The soluble fraction of the MMA-SS samples was comprised almost entirely of Cr. The small fraction of the GMA-MS sample that was soluble contained Mn with little Fe, while a more complex mixture was observed in the soluble portion of the GMA-SS sample, which contained Mn, Ni, Fe, Cr, and Cu. Data show that differences in the solubility of welding fumes influence the viability and ROS production of macrophages. The presence of soluble metals, such as Fe, Cr, Ni, Cu, and Mn, and the complexes formed by these different metals are likely important in the pulmonary responses observed after welding fume exposure."
1059985,Labra et al. 2010,The Combined Toxic and Genotoxic Effects of Chromium and Volatile Organic Contaminants to Pseudokirchneriella subcapitata,"In this report, the toxic effect of TCE (trichloroethylene), PCE (tetrachloroethylene), and potassium dichromate on P. subcapitata was investigated. The test was conducted at different concentrations of pollutants, starting from the European Community limit values defined for each analysed contaminant. Mixtures of pollutants were also tested to verify the combined effect of algae cells. Results suggest that both TCE and PCE were able to reduce P. subcapitata growth and metabolism starting from 0.05 and 0.02mgL super(-1) of contaminant, respectively. PCE seems to be substantially more toxic than TCE. Chromium produces a clear effect on algae growth and esterase activity only starting from 1mgL super(-1) of potassium dichromate; this result confirms the suitability of EU limit value. AFLP analysis showed that all tested pollutants produce DNA mutations probably due to oxygen radicals. Generally, chromium, at high concentrations, is more toxic and genotoxic that TCE or PCE. Test performed with a mixture of pollutants showed a synergic effect of chromium and organic compounds suggesting that the membrane damage induced from organic substances should increase the chromium cellular access.","The Combined Toxic and Genotoxic Effects of Chromium and Volatile Organic Contaminants to Pseudokirchneriella subcapitata Abs: In this report, the toxic effect of TCE (trichloroethylene), PCE (tetrachloroethylene), and potassium dichromate on P. subcapitata was investigated. The test was conducted at different concentrations of pollutants, starting from the European Community limit values defined for each analysed contaminant. Mixtures of pollutants were also tested to verify the combined effect of algae cells. Results suggest that both TCE and PCE were able to reduce P. subcapitata growth and metabolism starting from 0.05 and 0.02mgL super(-1) of contaminant, respectively. PCE seems to be substantially more toxic than TCE. Chromium produces a clear effect on algae growth and esterase activity only starting from 1mgL super(-1) of potassium dichromate; this result confirms the suitability of EU limit value. AFLP analysis showed that all tested pollutants produce DNA mutations probably due to oxygen radicals. Generally, chromium, at high concentrations, is more toxic and genotoxic that TCE or PCE. Test performed with a mixture of pollutants showed a synergic effect of chromium and organic compounds suggesting that the membrane damage induced from organic substances should increase the chromium cellular access."
1059807,Poljšak et al. 2006,Pro-oxidative versus antioxidative reactions between Trolox and Cr(VI): The role of H(2)O(2),"The effect of the Vitamin E model compound Trolox in reactions with Cr(VI) in the presence or absence of hydrogen peroxide was investigated. The aim of this study was to establish and discuss potential Trolox-mediated pro-oxidative reactions. The importance of the Trolox:Cr(VI) ratio in the Cr(VI) reduction process was determined from the EPR spectra and DNA cleavage reactions. In the absence of hydrogen peroxide, reduction of Cr(VI) occurred with concomitant oxidation of Trolox to the phenoxyl radical. In the presence of hydrogen peroxide, Cr(V), produced by the reduction of Cr(VI), reduced hydrogen peroxide to the hydroxyl radical. The latter was detected by spin-trapping the methyl radical following reaction with N-methyl sulfoxide. During Cr(VI) reduction with Trolox, DNA single- or double-strand breaks due to Trolox radical formation were not observed. Relaxed DNA appeared only when H(2)O(2) was added to Trolox/Cr(VI) mixtures most probably due to hydroxyl radical formation during the redox cycling of Cr(V/IV)-species. Fenton-like reactions do not play a significant role in the Trolox/Cr(VI) system in the absence of added H(2)O(2).","Pro-oxidative versus antioxidative reactions between Trolox and Cr(VI): The role of H(2)O(2) Abs: The effect of the Vitamin E model compound Trolox in reactions with Cr(VI) in the presence or absence of hydrogen peroxide was investigated. The aim of this study was to establish and discuss potential Trolox-mediated pro-oxidative reactions. The importance of the Trolox:Cr(VI) ratio in the Cr(VI) reduction process was determined from the EPR spectra and DNA cleavage reactions. In the absence of hydrogen peroxide, reduction of Cr(VI) occurred with concomitant oxidation of Trolox to the phenoxyl radical. In the presence of hydrogen peroxide, Cr(V), produced by the reduction of Cr(VI), reduced hydrogen peroxide to the hydroxyl radical. The latter was detected by spin-trapping the methyl radical following reaction with N-methyl sulfoxide. During Cr(VI) reduction with Trolox, DNA single- or double-strand breaks due to Trolox radical formation were not observed. Relaxed DNA appeared only when H(2)O(2) was added to Trolox/Cr(VI) mixtures most probably due to hydroxyl radical formation during the redox cycling of Cr(V/IV)-species. Fenton-like reactions do not play a significant role in the Trolox/Cr(VI) system in the absence of added H(2)O(2)."
1059489,Bulut et al. 2009,Leaching behavior of pollutants in ferrochrome arc furnace dust and its stabilization/solidification using ferrous sulphate and Portland cement,"In this study, dissolution properties under different conditions and pollution potential by toxicity characteristic leaching procedure (TCLP) of arc furnace dust generated in the production of ferrochrome were examined and some stabilization/solidification (S/S) techniques were applied to the dust depending on contaminants determined. Dissolution properties and pollution potentials of all the materials stabilized/solidified were also studied under the similar conditions. It was determined that the metallic components concentrations dissolved from the ferrochrome arc furnace dust (FAFD) except for chromium and zinc were below the detection limits. The chromium concentration dissolved from the FAFD by TCLP was found to be 9.8 mg/l. Portland cement (PC), PC-FeSO(4) and PC-sand-FeSO(4) mixtures for S/S of the FAFD were tested. Although metal ions in the cationic form were stabilized when the PC was only used, Cr(VI) in the sample was not changed depending on PC amount and remained in the soluble chromate form. The stabilization efficiency of Cr(VI) increased by the increasing amounts of PC and FeSO(4). The best S/S of the FAFD was accomplished when the 5 stoichiometric amounts of FeSO(4), 30% PC and 16% sand mixture were used. TCLP leaching results of the samples obtained under the optimum conditions were below the EPA landfilling limits.","Leaching behavior of pollutants in ferrochrome arc furnace dust and its stabilization/solidification using ferrous sulphate and Portland cement Abs: In this study, dissolution properties under different conditions and pollution potential by toxicity characteristic leaching procedure (TCLP) of arc furnace dust generated in the production of ferrochrome were examined and some stabilization/solidification (S/S) techniques were applied to the dust depending on contaminants determined. Dissolution properties and pollution potentials of all the materials stabilized/solidified were also studied under the similar conditions. It was determined that the metallic components concentrations dissolved from the ferrochrome arc furnace dust (FAFD) except for chromium and zinc were below the detection limits. The chromium concentration dissolved from the FAFD by TCLP was found to be 9.8 mg/l. Portland cement (PC), PC-FeSO(4) and PC-sand-FeSO(4) mixtures for S/S of the FAFD were tested. Although metal ions in the cationic form were stabilized when the PC was only used, Cr(VI) in the sample was not changed depending on PC amount and remained in the soluble chromate form. The stabilization efficiency of Cr(VI) increased by the increasing amounts of PC and FeSO(4). The best S/S of the FAFD was accomplished when the 5 stoichiometric amounts of FeSO(4), 30% PC and 16% sand mixture were used. TCLP leaching results of the samples obtained under the optimum conditions were below the EPA landfilling limits."
1059346,Kovacikova and  Chorvatovicova 1992,Inhalation Exposure of Rats to Metal Aerosol. I. Effects on Pulmonary Surfactant and Ascorbic Acid,"Pulmonary surfactant, a mixture of lipids and proteins, is stimulated by certain dusts. Female Wistar rats were exposed at 50 mg/m super(3) to nickel refinery aerosol for 5 h/d, 5 d/week for either four weeks or four months. At the end of the exposure period, pulmonary surfactant and ascorbic acid were determined for exposed and control animals. In the exposed animals, the amount of surfactant was 4.8 times higher than in the corresponding control group for both exposure durations. After four weeks of exposure, the level of pulmonary ascorbic acid was 56% higher than in the controls, but after four months of exposure, the level of ascorbic acid was only slightly increased.","Inhalation Exposure of Rats to Metal Aerosol. I. Effects on Pulmonary Surfactant and Ascorbic Acid Abs: Pulmonary surfactant, a mixture of lipids and proteins, is stimulated by certain dusts. Female Wistar rats were exposed at 50 mg/m super(3) to nickel refinery aerosol for 5 h/d, 5 d/week for either four weeks or four months. At the end of the exposure period, pulmonary surfactant and ascorbic acid were determined for exposed and control animals. In the exposed animals, the amount of surfactant was 4.8 times higher than in the corresponding control group for both exposure durations. After four weeks of exposure, the level of pulmonary ascorbic acid was 56% higher than in the controls, but after four months of exposure, the level of ascorbic acid was only slightly increased."
1058927,Sawatari and  Serita 1986,Determination of chromium speciation in fumes prepared by a plasma metal sprayer as a model of actual welding fumes,"Chromium in fumes generated in work environments including sites of welding work appears in various and complex states. Determination of chromium speciation in samples is useful for estimating the toxicity of such fumes. In the present study, determination of chromium speciation in chromium fumes prepared using a plasma metal sprayer, which are regarded as a model of actual fumes, was carried out. Fumes were treated with heated sodium carbonate solution, ammonium chloride-ammonia buffer solution at pH 9.5, Tris-HCl buffer solution at pH 7.5, hydrochloric acid, heated dilute sulfuric acid, distilled water, and a boiling mixture of sulfuric acid and perchloric acid in various series of the tests. The amounts of chromium (III) and chromium (VI) dissolved in each solution were determined, and the dissolution rates in those solutions were examined.","Determination of chromium speciation in fumes prepared by a plasma metal sprayer as a model of actual welding fumes Abs: Chromium in fumes generated in work environments including sites of welding work appears in various and complex states. Determination of chromium speciation in samples is useful for estimating the toxicity of such fumes. In the present study, determination of chromium speciation in chromium fumes prepared using a plasma metal sprayer, which are regarded as a model of actual fumes, was carried out. Fumes were treated with heated sodium carbonate solution, ammonium chloride-ammonia buffer solution at pH 9.5, Tris-HCl buffer solution at pH 7.5, hydrochloric acid, heated dilute sulfuric acid, distilled water, and a boiling mixture of sulfuric acid and perchloric acid in various series of the tests. The amounts of chromium (III) and chromium (VI) dissolved in each solution were determined, and the dissolution rates in those solutions were examined."
1058420,Jiao et al. 2011,Synchrotron-based XANES speciation of chromium in the oxy-fuel fly ash collected from lab-scale drop-tube furnace,"Speciation of chromium (Cr) in the fly ash collected from oxy-firing of Victorian brown coal has been reported for the first time to address the potential formation of toxic Cr(VI) and the variation of the quantities of Cr(III)-bearing species with flue gas composition. Synchrotron-based X-ray absorption near-edge structure (XANES) was employed for Cr speciation. Apart from a pure O(2)/CO(2) mixture (27/73, v/v) versus air, the O(2)/CO(2) mixtures doped with SO(2), HCl, and steam individually or together to simulate real flue gas have also been tested. Under all of the conditions tested here, the fractions of Cr(VI) in the fly ashes are insignificant, constituting no more than 5% of the total Cr. The test of Cr-doped brown coal in pyrolysis further confirmed that the Cr(VI) formation preferentially occurred through a local oxidation of Cr(III) at the oxygen-containing functions sites within coal matrix, rather than through an oxidation by external bulk O(2). This reaction is also highly temperature-dependent and slower than the interaction between Cr(III) and other metals such as iron oxide. Increasing temperature to 1000 °C inhibited the oxidation of Cr(IIII) to Cr(VI). Shifting the combustion gas from air to O(2)/CO(2) exerted little effect on the Cr(VI) formation. Instead, the formation of iron chromite (FeCr(2)O(4)) was facilitated in O(2)/CO(2), probably due to a strong reducing microenvironment formed by the CO(2) gasification reaction within the char matrix. The accumulation of HCl in flue gas favored the vaporization of chromium as gaseous chloride/oxychloride, as expected. The coexistence of SO(2) inhibited this phenomenon by promoting the formation of sulfate. The presence of steam was even beneficial for the inhibition of water-soluble Cr sulfate through stabilizing the majority of Cr into alumino-silicate which is in the slagging phase.","Synchrotron-based XANES speciation of chromium in the oxy-fuel fly ash collected from lab-scale drop-tube furnace Abs: Speciation of chromium (Cr) in the fly ash collected from oxy-firing of Victorian brown coal has been reported for the first time to address the potential formation of toxic Cr(VI) and the variation of the quantities of Cr(III)-bearing species with flue gas composition. Synchrotron-based X-ray absorption near-edge structure (XANES) was employed for Cr speciation. Apart from a pure O(2)/CO(2) mixture (27/73, v/v) versus air, the O(2)/CO(2) mixtures doped with SO(2), HCl, and steam individually or together to simulate real flue gas have also been tested. Under all of the conditions tested here, the fractions of Cr(VI) in the fly ashes are insignificant, constituting no more than 5% of the total Cr. The test of Cr-doped brown coal in pyrolysis further confirmed that the Cr(VI) formation preferentially occurred through a local oxidation of Cr(III) at the oxygen-containing functions sites within coal matrix, rather than through an oxidation by external bulk O(2). This reaction is also highly temperature-dependent and slower than the interaction between Cr(III) and other metals such as iron oxide. Increasing temperature to 1000 °C inhibited the oxidation of Cr(IIII) to Cr(VI). Shifting the combustion gas from air to O(2)/CO(2) exerted little effect on the Cr(VI) formation. Instead, the formation of iron chromite (FeCr(2)O(4)) was facilitated in O(2)/CO(2), probably due to a strong reducing microenvironment formed by the CO(2) gasification reaction within the char matrix. The accumulation of HCl in flue gas favored the vaporization of chromium as gaseous chloride/oxychloride, as expected. The coexistence of SO(2) inhibited this phenomenon by promoting the formation of sulfate. The presence of steam was even beneficial for the inhibition of water-soluble Cr sulfate through stabilizing the majority of Cr into alumino-silicate which is in the slagging phase."
1056767,Shakir et al. 2012,Ecotoxicological Risks Associated with Tannery Effluent Wastewater,"The problem of water pollution acquires greater relevance in the context of a developing agrarian economy like Pakistan. Even though, the leather industry is a leading economic sector in Pakistan, there is an increasing environmental concern regarding tanneries because they produce large amounts of potentially toxic wastewater containing both trivalent and hexavalent chromium, which are equally hazardous for human population, aquaculture and agricultural activities in the area. Therefore, we defined the scope of the present study as to employ different bioassays to determine the eco-toxic potential of tannery effluent wastewater (TW) and its chromium based components, i.e., potassium dichromate (K(2)Cr(2)O(7)) and chromium sulfate Cr(2)(SO(4))(3). Particle-induced X-ray emission (PIXE) analysis of TW was carried out to determine the concentration of chromium in TW and then equal concentrations of hexavalent (K(2)Cr(2)O(7)) and trivalent chromium Cr(2)(SO(4))(3) were obtained for this study. Cytotoxicity assay, artemia bioassay and phytotoxicity assay was utilized to investigate the eco-toxicological potential of different concentrations of TW, K(2)Cr(2)O(7) and Cr(2)(SO(4))(3). All the dilutions of TW, K(2)Cr(2)O(7) and Cr(2)(SO(4))(3) presented concentration dependent cytotoxic effects in these assays. The data clearly represents that among all three tested materials, different dilutions of K(2)Cr(2)O(7) caused significantly more damage (P&lt;0.001) to vero cell, brine shrimp and germination of maize seeds. Interestingly, the overall toxicity effects of TW treated groups were subsequent to K(2)Cr(2)O(7) treated group. Based on biological evidences presented in this article, it is concluded that hexavalent chromium (K(2)Cr(2)O(7)) and TW has got significant eco-damaging potential clearly elaborating that environmental burden in district Kasur is numerous and high levels of chromium is posing a considerable risk to the human population, aquaculture and agricultural industry that can obliterate ecosystem surrounding the tanneries.","Ecotoxicological Risks Associated with Tannery Effluent Wastewater Abs: The problem of water pollution acquires greater relevance in the context of a developing agrarian economy like Pakistan. Even though, the leather industry is a leading economic sector in Pakistan, there is an increasing environmental concern regarding tanneries because they produce large amounts of potentially toxic wastewater containing both trivalent and hexavalent chromium, which are equally hazardous for human population, aquaculture and agricultural activities in the area. Therefore, we defined the scope of the present study as to employ different bioassays to determine the eco-toxic potential of tannery effluent wastewater (TW) and its chromium based components, i.e., potassium dichromate (K(2)Cr(2)O(7)) and chromium sulfate Cr(2)(SO(4))(3). Particle-induced X-ray emission (PIXE) analysis of TW was carried out to determine the concentration of chromium in TW and then equal concentrations of hexavalent (K(2)Cr(2)O(7)) and trivalent chromium Cr(2)(SO(4))(3) were obtained for this study. Cytotoxicity assay, artemia bioassay and phytotoxicity assay was utilized to investigate the eco-toxicological potential of different concentrations of TW, K(2)Cr(2)O(7) and Cr(2)(SO(4))(3). All the dilutions of TW, K(2)Cr(2)O(7) and Cr(2)(SO(4))(3) presented concentration dependent cytotoxic effects in these assays. The data clearly represents that among all three tested materials, different dilutions of K(2)Cr(2)O(7) caused significantly more damage (P&lt;0.001) to vero cell, brine shrimp and germination of maize seeds. Interestingly, the overall toxicity effects of TW treated groups were subsequent to K(2)Cr(2)O(7) treated group. Based on biological evidences presented in this article, it is concluded that hexavalent chromium (K(2)Cr(2)O(7)) and TW has got significant eco-damaging potential clearly elaborating that environmental burden in district Kasur is numerous and high levels of chromium is posing a considerable risk to the human population, aquaculture and agricultural industry that can obliterate ecosystem surrounding the tanneries."
1056758,Schneider et al. 2012,Exposure to particulate hexavalent chromium exacerbates allergic asthma pathology,"Airborne hexavalent chromate, Cr(VI), has been identified by the Environmental Protection Agency as a possible health threat in urban areas, due to the carcinogenic potential of some of its forms. Particulate chromates are produced in many different industrial settings, with high levels of aerosolized forms historically documented. Along with an increased risk of lung cancer, a high incidence of allergic asthma has been reported in workers exposed to certain inhaled particulate Cr(VI) compounds. However, a direct causal association between Cr(VI) and allergic asthma has not been established. We recently showed that inhaled particulate Cr(VI) induces an innate neutrophilic inflammatory response in BALB/c mice. In the current studies we investigated how the inflammation induced by inhaled particulate Cr(VI) might alter the pathology of an allergic asthmatic response. We used a well-established mouse model of allergic asthma. Groups of ovalbumin protein (OVA)-primed mice were challenged either with OVA alone, or with a combination of OVA and particulate zinc chromate, and various parameters associated with asthmatic responses were measured. Co-exposure to particulate Cr(VI) and OVA mediated a mixed form of asthma in which both eosinophils and neutrophils are present in airways, tissue pathology is markedly exacerbated, and airway hyperresponsiveness is significantly increased. Taken together these findings suggest that inhalation of particulate forms of Cr(VI) may augment the severity of ongoing allergic asthma, as well as alter its phenotype. Such findings may have implications for asthmatics in settings in which airborne particulate Cr(VI) compounds are present at high levels.","Exposure to particulate hexavalent chromium exacerbates allergic asthma pathology Abs: Airborne hexavalent chromate, Cr(VI), has been identified by the Environmental Protection Agency as a possible health threat in urban areas, due to the carcinogenic potential of some of its forms. Particulate chromates are produced in many different industrial settings, with high levels of aerosolized forms historically documented. Along with an increased risk of lung cancer, a high incidence of allergic asthma has been reported in workers exposed to certain inhaled particulate Cr(VI) compounds. However, a direct causal association between Cr(VI) and allergic asthma has not been established. We recently showed that inhaled particulate Cr(VI) induces an innate neutrophilic inflammatory response in BALB/c mice. In the current studies we investigated how the inflammation induced by inhaled particulate Cr(VI) might alter the pathology of an allergic asthmatic response. We used a well-established mouse model of allergic asthma. Groups of ovalbumin protein (OVA)-primed mice were challenged either with OVA alone, or with a combination of OVA and particulate zinc chromate, and various parameters associated with asthmatic responses were measured. Co-exposure to particulate Cr(VI) and OVA mediated a mixed form of asthma in which both eosinophils and neutrophils are present in airways, tissue pathology is markedly exacerbated, and airway hyperresponsiveness is significantly increased. Taken together these findings suggest that inhalation of particulate forms of Cr(VI) may augment the severity of ongoing allergic asthma, as well as alter its phenotype. Such findings may have implications for asthmatics in settings in which airborne particulate Cr(VI) compounds are present at high levels."
1056644,Pandey et al. ,Effects of carbonation on the leachability and compressive strength of cement-solidified and geopolymer-solidified synthetic metal wastes,"The effects of accelerated carbonation on the compressive strength and leachability of fly ash-based geopolymer and ordinary portland cement (OPC) doped with Cd(II), Cr(III), Cr(VI), Cu(II), Pb(II) or Zn(II) salts were investigated. Cement was effective at immobilizing Cd, Cr(III), Cu, Pb and Zn under both the Synthetic Precipitation Leaching Procedure (SPLP) and the Toxicity Characteristic Leaching Procedure (TCLP), but ineffective for retaining Cr(VI). Carbonated cement maintained its ability to immobilize Cd, Cr(III), Pb and Zn, but, under acidic TCLP conditions, was much worse at retaining Cu. Geopolymer was effective at immobilizing Cr(III) and Cu, and, to a lesser degree, Cd, Pb and Zn in SPLP leaching tests. Only Cr(III) was immobilized under comparatively acidic TCLP testing conditions. Carbonation did not change the metal retention capacity of the geopolymer matrix. Metal doping caused compressive strengths of both geopolymer and cement to decrease. Carbonation increased the compressive strength of cement, but decreased that of the geopolymer. Geochemical equilibrium modeling provided insight on the mechanisms of metal immobilization.","Effects of carbonation on the leachability and compressive strength of cement-solidified and geopolymer-solidified synthetic metal wastes Abs: The effects of accelerated carbonation on the compressive strength and leachability of fly ash-based geopolymer and ordinary portland cement (OPC) doped with Cd(II), Cr(III), Cr(VI), Cu(II), Pb(II) or Zn(II) salts were investigated. Cement was effective at immobilizing Cd, Cr(III), Cu, Pb and Zn under both the Synthetic Precipitation Leaching Procedure (SPLP) and the Toxicity Characteristic Leaching Procedure (TCLP), but ineffective for retaining Cr(VI). Carbonated cement maintained its ability to immobilize Cd, Cr(III), Pb and Zn, but, under acidic TCLP conditions, was much worse at retaining Cu. Geopolymer was effective at immobilizing Cr(III) and Cu, and, to a lesser degree, Cd, Pb and Zn in SPLP leaching tests. Only Cr(III) was immobilized under comparatively acidic TCLP testing conditions. Carbonation did not change the metal retention capacity of the geopolymer matrix. Metal doping caused compressive strengths of both geopolymer and cement to decrease. Carbonation increased the compressive strength of cement, but decreased that of the geopolymer. Geochemical equilibrium modeling provided insight on the mechanisms of metal immobilization."
1056026,Kargacin et al. 1993,Mutagenic responses of nickel oxides and nickel sulfides in Chinese hamster V79 cell lines at the xanthine-guanine phosphoribosyl transferase locus,"Mutagenesis of several insoluble nickel compounds--crystalline nickel sulfide NiS, nickel subsulfide Ni3S2, nickel oxides (black and green) and soluble NiCl2 was studied in three Chinese hamster cell lines--at the hprt gene of the well-defined V79 cell line, and at gpt in two transgenic derivative cell lines G12 and G10. The transgenic cell line G12 responded very strongly to the insoluble Ni compounds, such that the gpt mutagenesis was at least 20 times higher than the spontaneous mutagenesis and in some experiments was even higher. In contrast the response of the G10 cells was much lower--the mutant frequencies only increased 2-3 times over the controls. In V79 cells, NiS and NiO (black) did not induce a mutagenic response at hprt. Soluble NiCl2 also exhibited no mutagenic activity in V79 cells and induced considerably lower activity than the insoluble compounds in the transgenic G12 cells. Following vitamin E pretreatment of G12 cells for 24 h prior to nickel exposure, increased cell survival was observed for several insoluble Ni compounds whereas vitamin E had no effect on NiCl2 cytotoxicity. With vitamin E pretreatment, significantly lower mutagenic responses in G12 cells were also noted for some insoluble Ni compounds, while no such effect was observed for NiCl2.","Mutagenic responses of nickel oxides and nickel sulfides in Chinese hamster V79 cell lines at the xanthine-guanine phosphoribosyl transferase locus Abs: Mutagenesis of several insoluble nickel compounds--crystalline nickel sulfide NiS, nickel subsulfide Ni3S2, nickel oxides (black and green) and soluble NiCl2 was studied in three Chinese hamster cell lines--at the hprt gene of the well-defined V79 cell line, and at gpt in two transgenic derivative cell lines G12 and G10. The transgenic cell line G12 responded very strongly to the insoluble Ni compounds, such that the gpt mutagenesis was at least 20 times higher than the spontaneous mutagenesis and in some experiments was even higher. In contrast the response of the G10 cells was much lower--the mutant frequencies only increased 2-3 times over the controls. In V79 cells, NiS and NiO (black) did not induce a mutagenic response at hprt. Soluble NiCl2 also exhibited no mutagenic activity in V79 cells and induced considerably lower activity than the insoluble compounds in the transgenic G12 cells. Following vitamin E pretreatment of G12 cells for 24 h prior to nickel exposure, increased cell survival was observed for several insoluble Ni compounds whereas vitamin E had no effect on NiCl2 cytotoxicity. With vitamin E pretreatment, significantly lower mutagenic responses in G12 cells were also noted for some insoluble Ni compounds, while no such effect was observed for NiCl2."
1055476,Deng et al. 2010,Removal of perfluorooctane sulfonate from wastewater by anion exchange resins: effects of resin properties and solution chemistry,"Perfluorooctane sulfonate (PFOS) is a new persistent organic pollutant of substantial environmental concern, and its removal from industrial wastewater is critical to eliminate its release into water environment. In this paper, six anion exchange resins with different polymer matrix, porosity, and functional group were evaluated for PFOS removal from simulated wastewater. Resin matrix displayed significant effect on the sorption kinetics and capacity of PFOS, and the polyacrylic resins including IRA67 and IRA958 exhibited faster sorption and higher sorption capacity for PFOS than the polystyrene resins due to the hydrophilic matrix. Sorption isotherms illustrated that the sorption capacity of PFOS on IRA67 and IRA958 was up to 4-5 mmol/g, and the amount of PFOS sorbed on the resins was more than chloride released from resins, indicating that other interactions besides anion exchange were involved in the sorption. Solution pH had little impact on the sorption of PFOS on IRA958, but displayed significant effect on IRA67 at pH above 10 due to the deprotonation of amine groups. The coexisting sulfate and hexavalent chromium in wastewater interfered with the sorption of PFOS because of their competitive sorption on the exchange sites. The spent resins were successfully regenerated using the mixture of NaCl and methanol solution. This work provided an understanding of sorption behavior and mechanism of PFOS on different anion exchange resins, and should result in more effective applications of ion exchange for PFOS removal from industrial wastewater.","Removal of perfluorooctane sulfonate from wastewater by anion exchange resins: effects of resin properties and solution chemistry Abs: Perfluorooctane sulfonate (PFOS) is a new persistent organic pollutant of substantial environmental concern, and its removal from industrial wastewater is critical to eliminate its release into water environment. In this paper, six anion exchange resins with different polymer matrix, porosity, and functional group were evaluated for PFOS removal from simulated wastewater. Resin matrix displayed significant effect on the sorption kinetics and capacity of PFOS, and the polyacrylic resins including IRA67 and IRA958 exhibited faster sorption and higher sorption capacity for PFOS than the polystyrene resins due to the hydrophilic matrix. Sorption isotherms illustrated that the sorption capacity of PFOS on IRA67 and IRA958 was up to 4-5 mmol/g, and the amount of PFOS sorbed on the resins was more than chloride released from resins, indicating that other interactions besides anion exchange were involved in the sorption. Solution pH had little impact on the sorption of PFOS on IRA958, but displayed significant effect on IRA67 at pH above 10 due to the deprotonation of amine groups. The coexisting sulfate and hexavalent chromium in wastewater interfered with the sorption of PFOS because of their competitive sorption on the exchange sites. The spent resins were successfully regenerated using the mixture of NaCl and methanol solution. This work provided an understanding of sorption behavior and mechanism of PFOS on different anion exchange resins, and should result in more effective applications of ion exchange for PFOS removal from industrial wastewater."
1050932,Banerjee et al. 2012,"Zinc oxide nano-particles--sonochemical synthesis, characterization and application for photo-remediation of heavy metal","Zinc oxide nanoparticles have been synthesized sonochemically from zinc acetate solution in aqueous methanol, ethanol and iso-propanol containing about 5 volume% of alcohol. Characterization with FESEM, XRD, AFM and BET surface area shows that the synthesized particles differ in shape and size. ZnO synthesized using isopropanol was observed to be the most crystalline one. The synthesized nanoparticles were used for the photocatalytic reduction of hexavalent chromium in aqueous medium under solar radiation. It was observed that the initial reduction rates varied with the difference in morphology of ZnO crystallites.","Zinc oxide nano-particles--sonochemical synthesis, characterization and application for photo-remediation of heavy metal Abs: Zinc oxide nanoparticles have been synthesized sonochemically from zinc acetate solution in aqueous methanol, ethanol and iso-propanol containing about 5 volume% of alcohol. Characterization with FESEM, XRD, AFM and BET surface area shows that the synthesized particles differ in shape and size. ZnO synthesized using isopropanol was observed to be the most crystalline one. The synthesized nanoparticles were used for the photocatalytic reduction of hexavalent chromium in aqueous medium under solar radiation. It was observed that the initial reduction rates varied with the difference in morphology of ZnO crystallites."
1049732,Wang and  Chiu 2007,Extraction of chromium(III) and chromium(VI) species from solid matrices using green solvent supercritical carbon dioxide,"Supercritical fluid extraction (SFE) provides an environmentally green technique to decontaminate chromium species from solid matrices using supercritical fluid carbon dioxide (ScCO2). Methanol and a small amount of water were found to significantly improve the extraction efficiency. The fluorinated chelating agent lithium bis(trifluoroethyl)-dithiocarbamate (LiFDDC) was effective in removing Cr ions in methanol-modified CO2 via in situ chelation/SFE technique. This paper indicates that the extraction efficiencies of Cr(III) and Cr(VI) from solid matrices can be greatly increased to more than 92% in the presence of a small amount of water, using 5% methanol-modified CO2 containing LiFDDC as an extractant. Chromium species in a wood waste sample in the form of chromated copper arsenate (CCA) can be extracted, but the extraction efficiency is not as good as expected, possibly due to the complications of the chemistry of Cr species in different oxidation states and to matrix effects.","Extraction of chromium(III) and chromium(VI) species from solid matrices using green solvent supercritical carbon dioxide Abs: Supercritical fluid extraction (SFE) provides an environmentally green technique to decontaminate chromium species from solid matrices using supercritical fluid carbon dioxide (ScCO2). Methanol and a small amount of water were found to significantly improve the extraction efficiency. The fluorinated chelating agent lithium bis(trifluoroethyl)-dithiocarbamate (LiFDDC) was effective in removing Cr ions in methanol-modified CO2 via in situ chelation/SFE technique. This paper indicates that the extraction efficiencies of Cr(III) and Cr(VI) from solid matrices can be greatly increased to more than 92% in the presence of a small amount of water, using 5% methanol-modified CO2 containing LiFDDC as an extractant. Chromium species in a wood waste sample in the form of chromated copper arsenate (CCA) can be extracted, but the extraction efficiency is not as good as expected, possibly due to the complications of the chemistry of Cr species in different oxidation states and to matrix effects."
1047982,Hori and  Iwasaki 2004,[Practical analysis of toxic substances useful for clinical toxicology-12-methanol],,[Practical analysis of toxic substances useful for clinical toxicology-12-methanol] Abs: 
1047096,Chen and  Cao 2005,Study on the photocatalytic reduction of dichromate and photocatalytic oxidation of dichlorvos,"In this paper, dichromate and dichlorvos are selected as the deputies of inorganic and organic pollutants, respectively, and TiO2/beads is used as a photocatalyst. The effects of various parameters, such as the amount of the photocatalyst, H2O2 concentration, metal ions, anions, pH value, and organic compounds on the photocatalytic reduction of dichromate and photocatalytic oxidation of dichlorvos are studied. From the studies, the differences of the parameters effect on the photocatalytic degradation of organic and inorganic pollutants are obtained. The results show that the optimum amount of the photocatalyst used is 6.0 g cm(-3) for the photocatalytic reactions. With the addition of a small amount of H2O2, the photocatalytic reduction of dichromate is inhibited while the photocatalytic oxidation of dichlorvos is accelerated. With the addition of trace amounts of Fe3+ or Cu2+, both the reactions are accelerated, and with the addition of Zn2+ and Na+, no obvious effects on the reactions are observed. Acidic solution is favorable for the photocatalytic reduction of dichromate; and acidic and alkaline solutions are favorable for the photocatalytic oxidation of dichlorvos. Adding SO4(2-), the photocatalytic oxidation is accelerated and adding Cl- the reaction is inhibited; and with the addition of trace amounts of SO4(2-), Cl- and NO3-, no obvious effects on the photocatalytic reduction of dichromate are observed. With the addition of methanol and toluene, the photocatalytic reduction of dichromate is accelerated, and the photocatalytic oxidation of dichlorvos is inhibited. The possible roles of the additives on the reactions are also discussed.","Study on the photocatalytic reduction of dichromate and photocatalytic oxidation of dichlorvos Abs: In this paper, dichromate and dichlorvos are selected as the deputies of inorganic and organic pollutants, respectively, and TiO2/beads is used as a photocatalyst. The effects of various parameters, such as the amount of the photocatalyst, H2O2 concentration, metal ions, anions, pH value, and organic compounds on the photocatalytic reduction of dichromate and photocatalytic oxidation of dichlorvos are studied. From the studies, the differences of the parameters effect on the photocatalytic degradation of organic and inorganic pollutants are obtained. The results show that the optimum amount of the photocatalyst used is 6.0 g cm(-3) for the photocatalytic reactions. With the addition of a small amount of H2O2, the photocatalytic reduction of dichromate is inhibited while the photocatalytic oxidation of dichlorvos is accelerated. With the addition of trace amounts of Fe3+ or Cu2+, both the reactions are accelerated, and with the addition of Zn2+ and Na+, no obvious effects on the reactions are observed. Acidic solution is favorable for the photocatalytic reduction of dichromate; and acidic and alkaline solutions are favorable for the photocatalytic oxidation of dichlorvos. Adding SO4(2-), the photocatalytic oxidation is accelerated and adding Cl- the reaction is inhibited; and with the addition of trace amounts of SO4(2-), Cl- and NO3-, no obvious effects on the photocatalytic reduction of dichromate are observed. With the addition of methanol and toluene, the photocatalytic reduction of dichromate is accelerated, and the photocatalytic oxidation of dichlorvos is inhibited. The possible roles of the additives on the reactions are also discussed."
1046412,Saleh et al. 2009,A validated HPLC method for separation and determination of promethazine enantiomers in pharmaceutical formulations,"A simple, rapid, and validated method for separation and determination of promethazine enantiomers was developed. Promethazine was separated and quantitated on a Vancomycin Chirobiotic V column (250 x 4.6 mm), using a mixture of methanol, acetic acid, and triethylamine (100:0.1:0.1%, by volume) as a mobile phase at 20 degrees C and at a flow rate of 1 mL/min. The UV-detector was set to 254 nm. Acetyl salicylic acid (Aspirin) was used as an internal standard. The applied HPLC method allowed separation and quantification of promethazine enantiomers with good linearity (r &gt; .999) in the studied range. The relative standard deviations (RSD) were 0.29 and 0.36 for the promethazine enantiomers with accuracy of 100.06 and 100.08. The limit of detection and limit of quantification of promethazine enantiomers were found to be 0.04 and 0.07 microg/mL, respectively. The method was validated through the parameters of linearity, accuracy, precision, and robustness. The HPLC method was applied for the quantitative determination of promethazine in pharmaceutical formulations.","A validated HPLC method for separation and determination of promethazine enantiomers in pharmaceutical formulations Abs: A simple, rapid, and validated method for separation and determination of promethazine enantiomers was developed. Promethazine was separated and quantitated on a Vancomycin Chirobiotic V column (250 x 4.6 mm), using a mixture of methanol, acetic acid, and triethylamine (100:0.1:0.1%, by volume) as a mobile phase at 20 degrees C and at a flow rate of 1 mL/min. The UV-detector was set to 254 nm. Acetyl salicylic acid (Aspirin) was used as an internal standard. The applied HPLC method allowed separation and quantification of promethazine enantiomers with good linearity (r &gt; .999) in the studied range. The relative standard deviations (RSD) were 0.29 and 0.36 for the promethazine enantiomers with accuracy of 100.06 and 100.08. The limit of detection and limit of quantification of promethazine enantiomers were found to be 0.04 and 0.07 microg/mL, respectively. The method was validated through the parameters of linearity, accuracy, precision, and robustness. The HPLC method was applied for the quantitative determination of promethazine in pharmaceutical formulations."
1043376,Hoshi et al. 1998,The simple and rapid spectrophotometric determination of trace chromium(VI) after preconcentration as its colored complex on chitin,"Preconcentration method with collection of metal complexes on a chitin has been applied to the spectrophotometric determination of chromium(VI) in water. The chromium(VI) is collected as its 1,5-diphenylcarbazide(DPC) complex on a column of chitin in the presence of dodecyl sulfate as counter-ion. The Cr-DPC complex retained on the chitin is eluted with a methanol-1 M acetic acid mixture (7:3, v/v), and the absorbance of the eluent is measured at 541 nm. Beer's law is obeyed over the concentration range of 0.05-0.6 mug of chromium(VI) in 1 ml of the eluent. The apparent molar absorptivity is 3.5x10(4) dm(3) mol(-1) cm(-1). The tolerance limits for Fe(III) is low, i.e. ten times that of chromium(VI), but some metal ions and common inorganic anions do not interfere in concentration range of 100-10 000 times that of chromium(VI). The present method can be applied to the determination of chromium(VI) in natural water samples.","The simple and rapid spectrophotometric determination of trace chromium(VI) after preconcentration as its colored complex on chitin Abs: Preconcentration method with collection of metal complexes on a chitin has been applied to the spectrophotometric determination of chromium(VI) in water. The chromium(VI) is collected as its 1,5-diphenylcarbazide(DPC) complex on a column of chitin in the presence of dodecyl sulfate as counter-ion. The Cr-DPC complex retained on the chitin is eluted with a methanol-1 M acetic acid mixture (7:3, v/v), and the absorbance of the eluent is measured at 541 nm. Beer's law is obeyed over the concentration range of 0.05-0.6 mug of chromium(VI) in 1 ml of the eluent. The apparent molar absorptivity is 3.5x10(4) dm(3) mol(-1) cm(-1). The tolerance limits for Fe(III) is low, i.e. ten times that of chromium(VI), but some metal ions and common inorganic anions do not interfere in concentration range of 100-10 000 times that of chromium(VI). The present method can be applied to the determination of chromium(VI) in natural water samples."
1043357,Foy and  Pacey 2000,Specific extraction of chromium(VI) using supercritical fluid extraction,"In some situations, it is no longer sufficient to give a total concentration of a metal. Instead, what is required to understand the potential toxicity of a sample is the concentration of metal species or oxidation state. When developing species specific methods, the major concern is that the integrity of the species ratio is not changed. In other words, the sample preparation or the analytical method will not convert metal ions from one oxidation state to another. Normal extraction techniques and chromatography methods have shown some tendencies to change species ratios. An ideal extraction method would extract the metal efficiently while retaining the metal's oxidation state. The properties of supercritical fluids should approach the ideal of retention of oxidation states. For example, the need for speciation of chromium is obvious since Cr(III) is considered an essential element while Cr(VI) is thought to be toxic and carcinogenic. This paper presents the results of a species specific extraction of Cr(VI) using two different carbamate derivatives as the chelator. Supercritical fluid extraction (SFE) coupled with a fluorinated dithiocarbamate and a methanol modifier allows extraction of 1 ppm Cr(VI) from a solid matrix with a recovery level of 88.4+/-2.57% using the NIST standard sample. The optimized conditions using the HP 7680 supercritical fluid extractor were: 0.1 ml of methanol, 0.05 ml of pure water, and 0.01 g of chelate via a saturation chamber.","Specific extraction of chromium(VI) using supercritical fluid extraction Abs: In some situations, it is no longer sufficient to give a total concentration of a metal. Instead, what is required to understand the potential toxicity of a sample is the concentration of metal species or oxidation state. When developing species specific methods, the major concern is that the integrity of the species ratio is not changed. In other words, the sample preparation or the analytical method will not convert metal ions from one oxidation state to another. Normal extraction techniques and chromatography methods have shown some tendencies to change species ratios. An ideal extraction method would extract the metal efficiently while retaining the metal's oxidation state. The properties of supercritical fluids should approach the ideal of retention of oxidation states. For example, the need for speciation of chromium is obvious since Cr(III) is considered an essential element while Cr(VI) is thought to be toxic and carcinogenic. This paper presents the results of a species specific extraction of Cr(VI) using two different carbamate derivatives as the chelator. Supercritical fluid extraction (SFE) coupled with a fluorinated dithiocarbamate and a methanol modifier allows extraction of 1 ppm Cr(VI) from a solid matrix with a recovery level of 88.4+/-2.57% using the NIST standard sample. The optimized conditions using the HP 7680 supercritical fluid extractor were: 0.1 ml of methanol, 0.05 ml of pure water, and 0.01 g of chelate via a saturation chamber."
1041414,Wang et al. 2010,Cloud point extraction combined with high-performance liquid chromatography for speciation of chromium(III) and chromium(VI) in environmental sediment samples,"A sensitive and simple method for high-performance liquid chromatography (HPLC) determination of traces of chromium species in lake sediments after preconcentration by cloud point extraction (CPE) has been developed. Simultaneous preconcentration of Cr(III) and Cr(VI) in sediment samples was achieved by CPE with 1-(2-thiazolylazo)-2-naphthol (TAN) as the chelating agent and non-ionic surfactant octylphenoxypolyethoxyethanol (Triton X-114) as the extractant. Baseline separation of the TAN chelates of Cr(III) and Cr(VI) was realized on a RP-C(18) column by using a mixture of methanol-water (69:31, v/v) solution and 4.5 mmol L(-1) CTMAB buffered with 0.03 mol L(-1) NaAc-HAc solution (pH 5.5) as the mobile phase at a flow rate of 0.8 mL min(-1). The variables affecting the complexation and extraction steps were examined. The precision (R.S.D.) for seven replicate injections of a mixture of 100 microg L(-1) of Cr(III) and Cr(VI) was 1.2 and 0.9% for the retention time, 4.7 and 2.7% for the peak area, respectively. The concentration factor was 45 for Cr(III) and 40 for Cr(VI). The detection limit (LOD) of this method, calculated as three times the standard deviation of the blank signals was 7.5 microg L(-1) for Cr(III) and 3.5 microg L(-1) for Cr(VI), respectively. The proposed procedure was applied to the speciation of chromium in sediment samples with satisfactory results.","Cloud point extraction combined with high-performance liquid chromatography for speciation of chromium(III) and chromium(VI) in environmental sediment samples Abs: A sensitive and simple method for high-performance liquid chromatography (HPLC) determination of traces of chromium species in lake sediments after preconcentration by cloud point extraction (CPE) has been developed. Simultaneous preconcentration of Cr(III) and Cr(VI) in sediment samples was achieved by CPE with 1-(2-thiazolylazo)-2-naphthol (TAN) as the chelating agent and non-ionic surfactant octylphenoxypolyethoxyethanol (Triton X-114) as the extractant. Baseline separation of the TAN chelates of Cr(III) and Cr(VI) was realized on a RP-C(18) column by using a mixture of methanol-water (69:31, v/v) solution and 4.5 mmol L(-1) CTMAB buffered with 0.03 mol L(-1) NaAc-HAc solution (pH 5.5) as the mobile phase at a flow rate of 0.8 mL min(-1). The variables affecting the complexation and extraction steps were examined. The precision (R.S.D.) for seven replicate injections of a mixture of 100 microg L(-1) of Cr(III) and Cr(VI) was 1.2 and 0.9% for the retention time, 4.7 and 2.7% for the peak area, respectively. The concentration factor was 45 for Cr(III) and 40 for Cr(VI). The detection limit (LOD) of this method, calculated as three times the standard deviation of the blank signals was 7.5 microg L(-1) for Cr(III) and 3.5 microg L(-1) for Cr(VI), respectively. The proposed procedure was applied to the speciation of chromium in sediment samples with satisfactory results."
1040766,Mohanty and  Cock 2010,Bioactivity of Syzygium jambos methanolic extracts: Antibacterial activity and toxicity,"Methanol extracts from S. jambos leaves were tested for antimicrobial activity and toxicity. S. jambos leaf extract inhibited the growth of 4 of the 14 bacteria tested (29%). Both gram-positive and gram-negative bacterial growths were inhibited by S. jambos leaf extract, although gram-positive bacteria appeared more susceptible. Two of the 10 gram-negative bacteria (20%) and 2 of the 4 gram-positive bacteria (50%) tested had their growths inhibited by the extract. The leaf extract also proved to be toxic in the Artemia franciscana bioassay, with a 48-h LC(50) of 387.9 ± 38.8 µg/mL, making it slightly more toxic than Mevinphos (505.3± 37.7 µg/mL) and approximately 5-fold less toxic than potassium dichromate (80.4 ± 4.3 µg/mL). Whilst potassium dichromate's LC(50) remained constant across the 72-hour test period (24-h LC(50), 86.3 ± 5.1; 72-h LC(50), 77.9 ± 4.9), the extract and Mevinphos LC(50) values decreased by 72 hours (87.0 ± 11.3 µg/mL and 103.9 ± 12.8 µg/mL, respectively), indicating their similar levels of toxicity in the assay.","Bioactivity of Syzygium jambos methanolic extracts: Antibacterial activity and toxicity Abs: Methanol extracts from S. jambos leaves were tested for antimicrobial activity and toxicity. S. jambos leaf extract inhibited the growth of 4 of the 14 bacteria tested (29%). Both gram-positive and gram-negative bacterial growths were inhibited by S. jambos leaf extract, although gram-positive bacteria appeared more susceptible. Two of the 10 gram-negative bacteria (20%) and 2 of the 4 gram-positive bacteria (50%) tested had their growths inhibited by the extract. The leaf extract also proved to be toxic in the Artemia franciscana bioassay, with a 48-h LC(50) of 387.9 ± 38.8 µg/mL, making it slightly more toxic than Mevinphos (505.3± 37.7 µg/mL) and approximately 5-fold less toxic than potassium dichromate (80.4 ± 4.3 µg/mL). Whilst potassium dichromate's LC(50) remained constant across the 72-hour test period (24-h LC(50), 86.3 ± 5.1; 72-h LC(50), 77.9 ± 4.9), the extract and Mevinphos LC(50) values decreased by 72 hours (87.0 ± 11.3 µg/mL and 103.9 ± 12.8 µg/mL, respectively), indicating their similar levels of toxicity in the assay."
1040415,Mulugeta et al. 2010,Optimization of an anion-exchange high performance liquid chromatography-inductively coupled plasma-mass spectrometric method for the speciation analysis of oxyanion-forming metals and metalloids in leachates from cement-based materials,"A method was developed for the speciation analysis of the oxyanions of As(III), As(V), Cr(VI), Mo(VI), Sb(III), Sb(V), Se(IV), Se(VI) and V(V) in leachates from cement-based materials, based on anion-exchange HPLC coupled with ICP-MS. The method was optimized in a two-step multivariate approach: the effect of sample pH and mobile phase composition on resolution, peak symmetry and analysis time was studied. Optimum conditions were then identified for the significant experimental factors by studying their interdependence. A mobile phase composition of 20 mM ammonium nitrate, 50 mM ammonium tartrate and pH 9.5 was found to be a compromise optimum for the separation of the target analytes using isocratic elution. The optimum condition provided separation of the analytes in less than 6 min, at a mobile phase flow rate of 1.0 mL/min. The signal intensities of the analytes were improved by adding 1% methanol to the mobile phase. The limit of detection of the method was in the range 0.2-2.2 ?g/L for the various species. The effect of sample constituents was studied using spiked concrete leachates. The method was used to determine the target oxyanionic species in leachates generated from a concrete material in the pH range 3.5-12.4; CrO(4)(2-), MoO(4)(2-) and VO(4)(3-) were detected in most of the leachates.","Optimization of an anion-exchange high performance liquid chromatography-inductively coupled plasma-mass spectrometric method for the speciation analysis of oxyanion-forming metals and metalloids in leachates from cement-based materials Abs: A method was developed for the speciation analysis of the oxyanions of As(III), As(V), Cr(VI), Mo(VI), Sb(III), Sb(V), Se(IV), Se(VI) and V(V) in leachates from cement-based materials, based on anion-exchange HPLC coupled with ICP-MS. The method was optimized in a two-step multivariate approach: the effect of sample pH and mobile phase composition on resolution, peak symmetry and analysis time was studied. Optimum conditions were then identified for the significant experimental factors by studying their interdependence. A mobile phase composition of 20 mM ammonium nitrate, 50 mM ammonium tartrate and pH 9.5 was found to be a compromise optimum for the separation of the target analytes using isocratic elution. The optimum condition provided separation of the analytes in less than 6 min, at a mobile phase flow rate of 1.0 mL/min. The signal intensities of the analytes were improved by adding 1% methanol to the mobile phase. The limit of detection of the method was in the range 0.2-2.2 ?g/L for the various species. The effect of sample constituents was studied using spiked concrete leachates. The method was used to determine the target oxyanionic species in leachates generated from a concrete material in the pH range 3.5-12.4; CrO(4)(2-), MoO(4)(2-) and VO(4)(3-) were detected in most of the leachates."
1038226,Daruliza et al. 2012,Anti-Candida activity and brine shrimp toxicity assay of Ganoderma boninense,"<strong>OBJECTIVES: </strong>Ganoderma (G.) boninense is a white rot fungus, which can be found in the palm oil tree. Several studies have shown that G. boninense has antimicrobial and antagonistic properties. However, there is limited information reported on antifungal properties especially on Candida (C) albicans. Hence, this study was conducted to determine the anti-Candida activity of G. boninense against C albicans.<br /><br /><strong>MATERIALS AND METHODS: </strong>Crude methanolic extracts of G. boninense was obtained by maceration method with 70% methanol. Anti-Candida test was carried out using disc diffusion assay, broth dilution method, time killing profile and brine shrimp toxicity assay.<br /><br /><strong>RESULTS AND CONCLUSIONS: </strong>Anti-Candida activity indicated that the mean zone of inhibition was 12.5 +/- 0.6 mm. The MIC value for C. albicans found to be 3.125 mg/ml. The result from time-killing profile showed that the growth of C albicans was inhibited hence decreases its exponential phase. For brine shrimp toxicity assay, the LC50 value was 3.59 mg/ml which proved that the extract of G. boninense is not toxic.","Anti-Candida activity and brine shrimp toxicity assay of Ganoderma boninense Abs: <strong>OBJECTIVES: </strong>Ganoderma (G.) boninense is a white rot fungus, which can be found in the palm oil tree. Several studies have shown that G. boninense has antimicrobial and antagonistic properties. However, there is limited information reported on antifungal properties especially on Candida (C) albicans. Hence, this study was conducted to determine the anti-Candida activity of G. boninense against C albicans.<br /><br /><strong>MATERIALS AND METHODS: </strong>Crude methanolic extracts of G. boninense was obtained by maceration method with 70% methanol. Anti-Candida test was carried out using disc diffusion assay, broth dilution method, time killing profile and brine shrimp toxicity assay.<br /><br /><strong>RESULTS AND CONCLUSIONS: </strong>Anti-Candida activity indicated that the mean zone of inhibition was 12.5 +/- 0.6 mm. The MIC value for C. albicans found to be 3.125 mg/ml. The result from time-killing profile showed that the growth of C albicans was inhibited hence decreases its exponential phase. For brine shrimp toxicity assay, the LC50 value was 3.59 mg/ml which proved that the extract of G. boninense is not toxic."
1035198,van Hoogstraten et al. 1992,Persistent immune tolerance to nickel and chromium by oral administration prior to cutaneous sensitization,"Oral administration of allergens, foreign proteins, or cell-bound antigens may induce systemic suppression of subsequent humoral and cell-mediated immune responses (&quot;oral tolerance&quot;). The induction of specific immune tolerance provides a potential strategy for treatment of T-cell-dependent immune diseases. Therefore, in depth studies into preconditions for optimal and persistent tolerance induction are mandatory. Here we report on such studies in a guinea pig model using the non-cross-reactive contact allergens nickel and chromium. Feeding per os of nickel sulfate or potassium dichromate did not trigger systemic TDTH-effector functions. Instead, short feeding periods led to a dose-dependent, and metal-specific, suppression of subsequently induced allergic contact hypersensitivity. Administration of the allergens onto the oral mucosa was most effective in the induction of immune tolerance. When first sensitizing attempts were delayed until 1 year after feeding, the degree of unresponsiveness was reduced. In contrast, with cutaneous contacts starting shortly after the feeding period, tolerance was fully stable and undiminished for at least 2 years. Thus, in orally treated guinea pigs cutaneous contacts provide boosting tolerogenic signals, supporting the view that oral tolerance does not result from clonal deletion but from active antigen-specific immunosuppression. Indeed, unresponsiveness to cutaneous immunization could be transferred by lymphoid cells from fed guinea pigs in a metal-specific way.","Persistent immune tolerance to nickel and chromium by oral administration prior to cutaneous sensitization Abs: Oral administration of allergens, foreign proteins, or cell-bound antigens may induce systemic suppression of subsequent humoral and cell-mediated immune responses (&quot;oral tolerance&quot;). The induction of specific immune tolerance provides a potential strategy for treatment of T-cell-dependent immune diseases. Therefore, in depth studies into preconditions for optimal and persistent tolerance induction are mandatory. Here we report on such studies in a guinea pig model using the non-cross-reactive contact allergens nickel and chromium. Feeding per os of nickel sulfate or potassium dichromate did not trigger systemic TDTH-effector functions. Instead, short feeding periods led to a dose-dependent, and metal-specific, suppression of subsequently induced allergic contact hypersensitivity. Administration of the allergens onto the oral mucosa was most effective in the induction of immune tolerance. When first sensitizing attempts were delayed until 1 year after feeding, the degree of unresponsiveness was reduced. In contrast, with cutaneous contacts starting shortly after the feeding period, tolerance was fully stable and undiminished for at least 2 years. Thus, in orally treated guinea pigs cutaneous contacts provide boosting tolerogenic signals, supporting the view that oral tolerance does not result from clonal deletion but from active antigen-specific immunosuppression. Indeed, unresponsiveness to cutaneous immunization could be transferred by lymphoid cells from fed guinea pigs in a metal-specific way."
1035170,Proctor and  Hong 2005,Relevance of rodent forestomach tumors in cancer risk assessment,"Studies have shown that most chemicals, which are known to be human carcinogens, also cause cancer in experimental animal models, but the converse is not as well established in that known animal carcinogens are not equally predictive of human carcinogenicity. A particularly controversial area in the use of animal data for human risk assessment is rodent forestomach tumors as a predictive tool for human carcinogenicity. Humans do not have a forestomach, but have histologically similar organs, including the oral cavity, pharynx, esophagus and glandular stomach. If tumors of the rodent forestomach are derived by a genotoxic mechanism, it is more likely that the agent is a human carcinogen as well. However, proliferative lesions in the rodent forestomach, including hyperplasia and compound-related tumors, may result from a combination of effects related to toxicokinetics, epithelial irritation, and/or dosing regimen and are less likely to be relevant for evaluating human carcinogenic potential. Hyperplasia is recognized as a preneoplastic lesion leading to forestomach papillomas and squamous cell carcinoma, but establishing the mechanism of action is critical to determining relevance to humans. We review the comparative anatomy and physiology of the rodent forestomach with human tissues and organs, forestomach tumor biology, regulatory practices and risk assessment guidance regarding the use of forestomach tumors for cancer risk assessment, examining specific chemicals, including benzo(a)pyrene, 1, 3-butadiene, epichlorohydrin, ethyl acrylate, hexavalent chromium, and mercuric chloride. A weight of evidence approach that combines criteria related to human exposure patterns, rodent tumor biology, genotoxicity, kinetics and comparative/mechanistic toxicology is proposed to evaluate human carcinogenic potential. Forestomach tumors resulting from chronic irritation associated with high-concentration drinking water and gavage dosing should not be used as the basis for determining carcinogenicity in humans or quantitative cancer potency estimates.","Relevance of rodent forestomach tumors in cancer risk assessment Abs: Studies have shown that most chemicals, which are known to be human carcinogens, also cause cancer in experimental animal models, but the converse is not as well established in that known animal carcinogens are not equally predictive of human carcinogenicity. A particularly controversial area in the use of animal data for human risk assessment is rodent forestomach tumors as a predictive tool for human carcinogenicity. Humans do not have a forestomach, but have histologically similar organs, including the oral cavity, pharynx, esophagus and glandular stomach. If tumors of the rodent forestomach are derived by a genotoxic mechanism, it is more likely that the agent is a human carcinogen as well. However, proliferative lesions in the rodent forestomach, including hyperplasia and compound-related tumors, may result from a combination of effects related to toxicokinetics, epithelial irritation, and/or dosing regimen and are less likely to be relevant for evaluating human carcinogenic potential. Hyperplasia is recognized as a preneoplastic lesion leading to forestomach papillomas and squamous cell carcinoma, but establishing the mechanism of action is critical to determining relevance to humans. We review the comparative anatomy and physiology of the rodent forestomach with human tissues and organs, forestomach tumor biology, regulatory practices and risk assessment guidance regarding the use of forestomach tumors for cancer risk assessment, examining specific chemicals, including benzo(a)pyrene, 1, 3-butadiene, epichlorohydrin, ethyl acrylate, hexavalent chromium, and mercuric chloride. A weight of evidence approach that combines criteria related to human exposure patterns, rodent tumor biology, genotoxicity, kinetics and comparative/mechanistic toxicology is proposed to evaluate human carcinogenic potential. Forestomach tumors resulting from chronic irritation associated with high-concentration drinking water and gavage dosing should not be used as the basis for determining carcinogenicity in humans or quantitative cancer potency estimates."
1035030,Pool-Zobel et al. 1994,Detection of genotoxic effects in human gastric and nasal mucosa cells isolated from biopsy samples,"To assess genotoxic burdens from chemicals, it is necessary to relate observations in experimental animals to humans. The success of this extrapolation would be increased by including data on chemical activities in human tissues. Therefore, we have developed techniques to assess DNA damage in human gastric and nasal mucosa (GM, NM) cells. Biopsy samples were obtained during gastroscopy from macroscopically healthy tissue of the stomach or from healthy nasal epithelia during surgery. The specimens were incubated for 30-45 min at 37 degrees C with a digestive solution. We obtained 1.5-8 x 10(6) GM cells and 5-10 x 10(5) NM cells per donor, both with viabilities of 80-95%. The cells were incubated in vitro for 1 hr at 37 degrees C with the test compounds added in their appropriate solvents. In GM cells, we studied N-methyl-N'-nitro-N-nitrosoguanidine (MNNG), sodium dichromate (Na2Cr2O7), nickel sulphate (NiSO4), cadmium sulphate (CdSO4), and lindane. In NM cells, lindane was investigated. Each compound was assessed for DNA damaging activity in cells of at least three different human donor samples using the microgel single cell assay. Similar studies were performed with GM and NM cells obtained from Sprague-Dawley rats. We have found human GM cells to be more sensitive to the genotoxic activity of MNNG than rat GM cells (low effective concentration [LEC] = 0.16 and 0.625 micrograms/ml for human and rat, respectively). Human cells were also more sensitive to the cytotoxic/genotoxic activity of NiSO4 (LEC = 5 and 19 mumoles/ml for human and rat, respectively). CdSO4 was genotoxic in human GM cells (LEC = 0.03-0.125 mumoles/ml), whereas no dose-related genotoxicity was observed in rat GM at concentrations up to 0.5 mumoles/ml. In contrast, approximately equal responses regarding genotoxicity and cytotoxicity were observed in rat and human GM for Na2Cr2O7 (0.25-1 mumoles/ml). Lindane, however, was genotoxic in three out of four rat GM but not in human GM cells (0.5-1 mumoles/ml), whereas it was active in both rat and human NM cells. Together with other recently published in vivo findings, our results with lindane can be interpreted according to a parallelogram approach. In view of possible human exposure situations and the sensitivities of the two target tissues from both species, the data imply that lindane will pose a health risk to humans by inhalation but not by ingestion.","Detection of genotoxic effects in human gastric and nasal mucosa cells isolated from biopsy samples Abs: To assess genotoxic burdens from chemicals, it is necessary to relate observations in experimental animals to humans. The success of this extrapolation would be increased by including data on chemical activities in human tissues. Therefore, we have developed techniques to assess DNA damage in human gastric and nasal mucosa (GM, NM) cells. Biopsy samples were obtained during gastroscopy from macroscopically healthy tissue of the stomach or from healthy nasal epithelia during surgery. The specimens were incubated for 30-45 min at 37 degrees C with a digestive solution. We obtained 1.5-8 x 10(6) GM cells and 5-10 x 10(5) NM cells per donor, both with viabilities of 80-95%. The cells were incubated in vitro for 1 hr at 37 degrees C with the test compounds added in their appropriate solvents. In GM cells, we studied N-methyl-N'-nitro-N-nitrosoguanidine (MNNG), sodium dichromate (Na2Cr2O7), nickel sulphate (NiSO4), cadmium sulphate (CdSO4), and lindane. In NM cells, lindane was investigated. Each compound was assessed for DNA damaging activity in cells of at least three different human donor samples using the microgel single cell assay. Similar studies were performed with GM and NM cells obtained from Sprague-Dawley rats. We have found human GM cells to be more sensitive to the genotoxic activity of MNNG than rat GM cells (low effective concentration [LEC] = 0.16 and 0.625 micrograms/ml for human and rat, respectively). Human cells were also more sensitive to the cytotoxic/genotoxic activity of NiSO4 (LEC = 5 and 19 mumoles/ml for human and rat, respectively). CdSO4 was genotoxic in human GM cells (LEC = 0.03-0.125 mumoles/ml), whereas no dose-related genotoxicity was observed in rat GM at concentrations up to 0.5 mumoles/ml. In contrast, approximately equal responses regarding genotoxicity and cytotoxicity were observed in rat and human GM for Na2Cr2O7 (0.25-1 mumoles/ml). Lindane, however, was genotoxic in three out of four rat GM but not in human GM cells (0.5-1 mumoles/ml), whereas it was active in both rat and human NM cells. Together with other recently published in vivo findings, our results with lindane can be interpreted according to a parallelogram approach. In view of possible human exposure situations and the sensitivities of the two target tissues from both species, the data imply that lindane will pose a health risk to humans by inhalation but not by ingestion."
1034937,Webb and  Carter 1984,An improved wet digestion procedure for the analysis of total arsenic in biological samples by direct hydride atomic absorption spectrophotometry,"The presence of dimethylarsinic acid (DMAA) in biological samples can cause an underestimation of total arsenic content when analyzed relative to an inorganic arsenic standard by direct hydride flame atomic absorption spectrophotometry. An acid digestion procedure is described that quantitatively recovers DMAA as well as monomethylarsonic acid, inorganic arsenic(III), and arsenic(V) from aqueous and biological samples. Methylated arsenicals are converted to inorganic arsenic by wet digestion with HNO3, H2SO4, and K2Cr2O7 and subsequently reduced to arsenic(III) with Nal. Arsine is generated with NaBH4 and converted to atomic arsenic following immediate introduction into a nitrogen-entrained air-hydrogen flame. This method produces a linear relationship to absorbance within a mass range of 50 to 300 ng arsenic/arsine reaction. A sensitivity of 2 ng arsenic and a detection limit of 7 ng arsenic/arsine reaction were also obtained. Recovery of DMAA from water, urine, feces, or whole blood ranged from 92 to 105% with a coefficient of variation of 5 to 10%.","An improved wet digestion procedure for the analysis of total arsenic in biological samples by direct hydride atomic absorption spectrophotometry Abs: The presence of dimethylarsinic acid (DMAA) in biological samples can cause an underestimation of total arsenic content when analyzed relative to an inorganic arsenic standard by direct hydride flame atomic absorption spectrophotometry. An acid digestion procedure is described that quantitatively recovers DMAA as well as monomethylarsonic acid, inorganic arsenic(III), and arsenic(V) from aqueous and biological samples. Methylated arsenicals are converted to inorganic arsenic by wet digestion with HNO3, H2SO4, and K2Cr2O7 and subsequently reduced to arsenic(III) with Nal. Arsine is generated with NaBH4 and converted to atomic arsenic following immediate introduction into a nitrogen-entrained air-hydrogen flame. This method produces a linear relationship to absorbance within a mass range of 50 to 300 ng arsenic/arsine reaction. A sensitivity of 2 ng arsenic and a detection limit of 7 ng arsenic/arsine reaction were also obtained. Recovery of DMAA from water, urine, feces, or whole blood ranged from 92 to 105% with a coefficient of variation of 5 to 10%."
1034488,Kharab and  Singh 1985,"Genotoxic effects of potassium dichromate, sodium arsenite, cobalt chloride and lead nitrate in diploid yeast","4 metal salts, potassium dichromate, sodium arsenite, cobalt chloride and lead nitrate were tested for their genotoxic effects in Saccharomyces cerevisiae. Potassium dichromate was the most potent agent for induction of gene conversion and reverse mutation. Sodium arsenite was virtually ineffective as a convertogen but gave a positive result for reversion. Cobalt chloride was the least toxic, exhibited a convertogenic activity but was only marginally active for reverse mutation. Lead nitrate was the most toxic salt but was genetically inactive.","Genotoxic effects of potassium dichromate, sodium arsenite, cobalt chloride and lead nitrate in diploid yeast Abs: 4 metal salts, potassium dichromate, sodium arsenite, cobalt chloride and lead nitrate were tested for their genotoxic effects in Saccharomyces cerevisiae. Potassium dichromate was the most potent agent for induction of gene conversion and reverse mutation. Sodium arsenite was virtually ineffective as a convertogen but gave a positive result for reversion. Cobalt chloride was the least toxic, exhibited a convertogenic activity but was only marginally active for reverse mutation. Lead nitrate was the most toxic salt but was genetically inactive."
1034435,de Ruiter et al. 1985,"Effect of heavy metals on cellular growth, metabolism and integrity of cultured Chinese hamster kidney cells","The effects of CdCl2, Na2CrO4, NaAsO2 and NiSO4 on cultured Chinese hamster kidney cells were studied over a concentration range for 48 h. Release of lactate dehydrogenase, a parameter of cell viability, was not closely related to cell proliferation except for Na2CrO4. A better correlation was obtained between glucose consumption and lactate production, and cellular growth. When studying toxic effects of metals in cell-culture systems, metabolic parameters should be determined in addition to cell viability and cellular growth. The results indicate that Chinese hamster kidney cells in culture might be useful to study mechanisms of metal-induced toxicity.","Effect of heavy metals on cellular growth, metabolism and integrity of cultured Chinese hamster kidney cells Abs: The effects of CdCl2, Na2CrO4, NaAsO2 and NiSO4 on cultured Chinese hamster kidney cells were studied over a concentration range for 48 h. Release of lactate dehydrogenase, a parameter of cell viability, was not closely related to cell proliferation except for Na2CrO4. A better correlation was obtained between glucose consumption and lactate production, and cellular growth. When studying toxic effects of metals in cell-culture systems, metabolic parameters should be determined in addition to cell viability and cellular growth. The results indicate that Chinese hamster kidney cells in culture might be useful to study mechanisms of metal-induced toxicity."
1033994,Stern 1983,Assessment of risk of lung cancer for welders,"Certain welding fumes contain significant amounts of chromium, manganese, and nickel, and trace amounts of arsenic and lead. These metals exhibit mutagenicity in one or more in vitro bioassays, and several are strongly suspected human carcinogens, albeit in unknown forms. It might, therefore, be expected that welders experience an excess risk of respiratory tract cancer because of their occupation. A survey of the world literature has disclosed 22 epidemiological studies of cancer incidence among welders, 16 of which yield a total of 586 cases of lung cancer observed, based on approximately 600,000 man-years at risk; a risk ratio of less than unity was excluded within 95% confidence limits for 5 of these studies. A risk ratio of 1.3 was not excluded in any study. Although there may be many possible origins to the excess risk, if welders of stainless steels suffer an &quot;equivalent lung cancer risk&quot; to that of chromate workers because of their equivalent chromium (VI) exposure, then a resulting three-fold risk ratio for 10% of all welders engaged in stainless steel welding would account for the total over-incidence experienced by the entire occupational group.","Assessment of risk of lung cancer for welders Abs: Certain welding fumes contain significant amounts of chromium, manganese, and nickel, and trace amounts of arsenic and lead. These metals exhibit mutagenicity in one or more in vitro bioassays, and several are strongly suspected human carcinogens, albeit in unknown forms. It might, therefore, be expected that welders experience an excess risk of respiratory tract cancer because of their occupation. A survey of the world literature has disclosed 22 epidemiological studies of cancer incidence among welders, 16 of which yield a total of 586 cases of lung cancer observed, based on approximately 600,000 man-years at risk; a risk ratio of less than unity was excluded within 95% confidence limits for 5 of these studies. A risk ratio of 1.3 was not excluded in any study. Although there may be many possible origins to the excess risk, if welders of stainless steels suffer an &quot;equivalent lung cancer risk&quot; to that of chromate workers because of their equivalent chromium (VI) exposure, then a resulting three-fold risk ratio for 10% of all welders engaged in stainless steel welding would account for the total over-incidence experienced by the entire occupational group."
1033125,Brandi et al. 1990,Growth delay and filamentation of Escherichia coli wild-type and Rec A cells in response to hexavalent chromium and other metal compounds,"The effects of hexavalent chromium (7440473) were investigated, focusing on the cytotoxic and filamentous response elicited by exposure of logarithmically growing Escherichia-coli (E-coli) wild type and Rec-A deficient strains to increasing concentrations of potassium-chromate (7789006). The effect of other metal compounds was also studied. E-coli cells were exposed to a wide range of potassium-chromate concentrations in the medium and, at various time intervals, cell growth was estimated in terms of turbidity at 600 nanometers. The turbidity of cultures of wild type E-coli was not significantly changed by concentrations of potassium-chromate below 8 micromolar (microM). At 16microM a slight reduction in turbidity occurred, but only after 3 hours of growth in the presence of the metal compound. A much higher toxicity was noted at 32microM concentrations. The Rec-A cells were more sensitive than the wild type strain. The findings indicated that the filamentous response is a sensitive parameter for monitoring metal compounds with an ability to induce DNA damage, although caution must be taken in interpreting negative results since other effects elicited by the metal itself may mask this type of response.","Growth delay and filamentation of Escherichia coli wild-type and Rec A cells in response to hexavalent chromium and other metal compounds Abs: The effects of hexavalent chromium (7440473) were investigated, focusing on the cytotoxic and filamentous response elicited by exposure of logarithmically growing Escherichia-coli (E-coli) wild type and Rec-A deficient strains to increasing concentrations of potassium-chromate (7789006). The effect of other metal compounds was also studied. E-coli cells were exposed to a wide range of potassium-chromate concentrations in the medium and, at various time intervals, cell growth was estimated in terms of turbidity at 600 nanometers. The turbidity of cultures of wild type E-coli was not significantly changed by concentrations of potassium-chromate below 8 micromolar (microM). At 16microM a slight reduction in turbidity occurred, but only after 3 hours of growth in the presence of the metal compound. A much higher toxicity was noted at 32microM concentrations. The Rec-A cells were more sensitive than the wild type strain. The findings indicated that the filamentous response is a sensitive parameter for monitoring metal compounds with an ability to induce DNA damage, although caution must be taken in interpreting negative results since other effects elicited by the metal itself may mask this type of response."
1032537,Saffiotti and  Bertolero 1989,Neoplastic transformation of BALB/3T3 cells by metals and the quest for induction of a metastatic phenotype,"In the mouse embryo cell line BALB/3T3 Clone A31-1-1, dose-dependent morphologic neoplastic transformation was obtained with NaAsO2, Na2HAsO4, CdCl2, and K2CrO4. Cellular uptake was four fold higher for As3+ than for As5+, and As5- was metabolized to As3+ in cytosol. Cytotoxicity and transformation rates were four fold higher for As3+ than As5+, but when correlated to cellular As burden they were equivalent. As3+ appears responsible for the transforming activity. The foci transformed by metals (or by other carcinogens) gave rise to tumorigenic cell lines (sc sarcomas in nude mice), none of which, however, induced metastases when tested by sc or by iv injection in nude mice. Thus carcinogens change this aneuploid cell line from a preneoplastic stage to the expression of malignant growth but not of metastatic activity. Metastatic and type IV collagenolytic activities can be induced by transfection of the c-Ha-ras oncogene and inhibited by the Ad2-E1a gene (so far shown in other cell types). It remains to be seen whether metal or other carcinogens can induce the nonmetastatic phenotype to become metastatic. The molecular mechanisms of metal carcinogenesis, studied in cell culture systems, in combination with other factors or oncogenes, may reveal the effect of individual metal carcinogens on discrete steps of the complex process of carcinogenesis.","Neoplastic transformation of BALB/3T3 cells by metals and the quest for induction of a metastatic phenotype Abs: In the mouse embryo cell line BALB/3T3 Clone A31-1-1, dose-dependent morphologic neoplastic transformation was obtained with NaAsO2, Na2HAsO4, CdCl2, and K2CrO4. Cellular uptake was four fold higher for As3+ than for As5+, and As5- was metabolized to As3+ in cytosol. Cytotoxicity and transformation rates were four fold higher for As3+ than As5+, but when correlated to cellular As burden they were equivalent. As3+ appears responsible for the transforming activity. The foci transformed by metals (or by other carcinogens) gave rise to tumorigenic cell lines (sc sarcomas in nude mice), none of which, however, induced metastases when tested by sc or by iv injection in nude mice. Thus carcinogens change this aneuploid cell line from a preneoplastic stage to the expression of malignant growth but not of metastatic activity. Metastatic and type IV collagenolytic activities can be induced by transfection of the c-Ha-ras oncogene and inhibited by the Ad2-E1a gene (so far shown in other cell types). It remains to be seen whether metal or other carcinogens can induce the nonmetastatic phenotype to become metastatic. The molecular mechanisms of metal carcinogenesis, studied in cell culture systems, in combination with other factors or oncogenes, may reveal the effect of individual metal carcinogens on discrete steps of the complex process of carcinogenesis."
1032475,Otsuka and  Ohsawa 1991,Differential susceptibility of T- and B-lymphocyte proliferation to cadmium: relevance to zinc requirement in T-lymphocyte proliferation,"Effect of zinc on an inhibitory action of cadmium to mitogen-induced lymphocyte proliferation was investigated. Cadmium at concentrations below 10 microM selectively inhibited concanavalin A-induced T-cell proliferation as compared with bacterial lipopolysaccharide-induced B-cell proliferation. Such differential susceptibility of T- and B-cell proliferation was not observed in the cases of other cations such as mercury, lead, nickel, molybdenum, chromium(VI) and arsenic (V). The inhibitory effect of 10 microM cadmium on T-cell proliferation was almost completely prevented by addition of 30 microM zinc to the culture medium, but was not by ferrous iron, nickel and copper. Further, cadmium exerted the same extent of inhibition even when it was added at 16 h after concanavalin A stimulation, and thereafter the inhibition gradually decreased. Correlated well with this observation, the protective effect of zinc was seen as far as it existed during the first 16 h of the mitogen stimulation. As intracellular cadmium content and a cadmium-induced metallothionein level were not changed by zinc addition, these observations strongly suggest that cadmium inhibits some zinc-dependent processes required for T-cell proliferation.","Differential susceptibility of T- and B-lymphocyte proliferation to cadmium: relevance to zinc requirement in T-lymphocyte proliferation Abs: Effect of zinc on an inhibitory action of cadmium to mitogen-induced lymphocyte proliferation was investigated. Cadmium at concentrations below 10 microM selectively inhibited concanavalin A-induced T-cell proliferation as compared with bacterial lipopolysaccharide-induced B-cell proliferation. Such differential susceptibility of T- and B-cell proliferation was not observed in the cases of other cations such as mercury, lead, nickel, molybdenum, chromium(VI) and arsenic (V). The inhibitory effect of 10 microM cadmium on T-cell proliferation was almost completely prevented by addition of 30 microM zinc to the culture medium, but was not by ferrous iron, nickel and copper. Further, cadmium exerted the same extent of inhibition even when it was added at 16 h after concanavalin A stimulation, and thereafter the inhibition gradually decreased. Correlated well with this observation, the protective effect of zinc was seen as far as it existed during the first 16 h of the mitogen stimulation. As intracellular cadmium content and a cadmium-induced metallothionein level were not changed by zinc addition, these observations strongly suggest that cadmium inhibits some zinc-dependent processes required for T-cell proliferation."
1032213,Hallenbeck et al. 1993,Cancer risk assessment for the inhalation of metals from municipal solid waste incinerators impacting Chicago,BIOSIS COPYRIGHT: BIOL ABS. RRM HUMAN AIR POLLUTION EFFECTS WASTE MANAGEMENT WEATHER CARCINOGEN INDUSTRIAL EMISSIONS HEAVY METALS ARSENIC BERYLLIUM CADMIUM CHROMIUM-VI 6 RISK ASSESSMENT EPA USA,Cancer risk assessment for the inhalation of metals from municipal solid waste incinerators impacting Chicago Abs: BIOSIS COPYRIGHT: BIOL ABS. RRM HUMAN AIR POLLUTION EFFECTS WASTE MANAGEMENT WEATHER CARCINOGEN INDUSTRIAL EMISSIONS HEAVY METALS ARSENIC BERYLLIUM CADMIUM CHROMIUM-VI 6 RISK ASSESSMENT EPA USA
1032078,Norseth 1988,Metal carcinogenesis,"Although case reports suggesting arsenic as a carcinogen appeared as early as 1880, and similar reports for chromium and nickel appeared in the 1930s, only in the last decades has there been a growing recognition of metals as an important class of occupational and environmental carcinogens. Extensive epidemiologic evidence has been published for an increased cancer risk in workers occupationally exposed to arsenic, chromium and nickel; more limited evidence exists for beryllium and cadmium. These epidemiologic results for some compounds for these metals have been properly supported by both animal studies and a number of short-term tests, but the mechanisms of action are still uncertain. In addition, experimental carcinogenesis have been demonstrated for lead and cis-platinum drugs, and limited experimental evidence of local sarcomas or teratomas exists for certain compounds of aluminum, manganese, titanium, copper and zinc.","Metal carcinogenesis Abs: Although case reports suggesting arsenic as a carcinogen appeared as early as 1880, and similar reports for chromium and nickel appeared in the 1930s, only in the last decades has there been a growing recognition of metals as an important class of occupational and environmental carcinogens. Extensive epidemiologic evidence has been published for an increased cancer risk in workers occupationally exposed to arsenic, chromium and nickel; more limited evidence exists for beryllium and cadmium. These epidemiologic results for some compounds for these metals have been properly supported by both animal studies and a number of short-term tests, but the mechanisms of action are still uncertain. In addition, experimental carcinogenesis have been demonstrated for lead and cis-platinum drugs, and limited experimental evidence of local sarcomas or teratomas exists for certain compounds of aluminum, manganese, titanium, copper and zinc."
1031466,Smith and  Steinmaus 2009,Health effects of arsenic and chromium in drinking water: recent human findings,"Even at high concentrations, arsenic-contaminated water is translucent, tasteless, and odorless. Yet almost every day, studies report a continually increasing plethora of toxic effects that have manifested in exposed populations throughout the world. In this article we focus on recent findings, in particular those associated with major contributions since 2006. Early life exposure, both in utero and in childhood, has been receiving increased attention, and remarkable increases in consequent mortality in young adults have been reported. New studies address the dose-response relationship between drinking-water arsenic concentrations and skin lesions, and new findings have emerged concerning arsenic and cardiovascular disease. We also review the increasing epidemiological evidence that the first step of methylation of inorganic arsenic to monomethylated arsenic (MMA) is actually an activation step rather than the first step in detoxification, as once thought. Hexavalent chromium differs from arsenic in that it discolors water, turning the water yellow at high concentrations. A controversial issue is whether chromium causes cancer when ingested. A recent publication supports the original findings in China of increased cancer mortality in a population where well water turned yellow with chromium.","Health effects of arsenic and chromium in drinking water: recent human findings Abs: Even at high concentrations, arsenic-contaminated water is translucent, tasteless, and odorless. Yet almost every day, studies report a continually increasing plethora of toxic effects that have manifested in exposed populations throughout the world. In this article we focus on recent findings, in particular those associated with major contributions since 2006. Early life exposure, both in utero and in childhood, has been receiving increased attention, and remarkable increases in consequent mortality in young adults have been reported. New studies address the dose-response relationship between drinking-water arsenic concentrations and skin lesions, and new findings have emerged concerning arsenic and cardiovascular disease. We also review the increasing epidemiological evidence that the first step of methylation of inorganic arsenic to monomethylated arsenic (MMA) is actually an activation step rather than the first step in detoxification, as once thought. Hexavalent chromium differs from arsenic in that it discolors water, turning the water yellow at high concentrations. A controversial issue is whether chromium causes cancer when ingested. A recent publication supports the original findings in China of increased cancer mortality in a population where well water turned yellow with chromium."
1030873,Norseth 1980,Asbestos and metals as carcinogens,"Increased incidences of lung carcinoma and pleural mesothelioma in humans exposed to asbestos have been irrefutably established. Different forms of asbestos may have different tumorigenic activities, depending on surface properties, durability, and size of the fibers. A number of metals, such as nickel, chromium, and arsenic, are known to be carcinogenic to humans; for beryllium and cadmium the epidemiologic evidence is less extensive. All these metals also induce genetic toxicity in vitro. For chromium the molecular mechanism of metal tumorigenesis has been extensively investigated; the hexavalent form is generally a much more potent mutagen than is chromium (III). Solubility seems to be necessary for the genotoxicity of nickel. At present it cannot be concluded that all metals act by the same carcinogenic mechanism, even though direct modification of DNA seems to be the common experimental finding.","Asbestos and metals as carcinogens Abs: Increased incidences of lung carcinoma and pleural mesothelioma in humans exposed to asbestos have been irrefutably established. Different forms of asbestos may have different tumorigenic activities, depending on surface properties, durability, and size of the fibers. A number of metals, such as nickel, chromium, and arsenic, are known to be carcinogenic to humans; for beryllium and cadmium the epidemiologic evidence is less extensive. All these metals also induce genetic toxicity in vitro. For chromium the molecular mechanism of metal tumorigenesis has been extensively investigated; the hexavalent form is generally a much more potent mutagen than is chromium (III). Solubility seems to be necessary for the genotoxicity of nickel. At present it cannot be concluded that all metals act by the same carcinogenic mechanism, even though direct modification of DNA seems to be the common experimental finding."
1030839,Castillo et al. 2008,Capabilities of microbore columns coupled to inductively coupled plasma mass spectrometry in speciation of arsenic and selenium,"The performance of microHPLC-microconcentric nebulizer-inductively coupled plasma-mass spectrometry (ICP-MS) coupling for the simultaneous determination of As(III), As(V), monomethylarsenic acid (MMA), dimethylarsinic acid (DMA), selenite (SeIV) and selenate (SeVI) in water was evaluated. The accurate reduction of the off-column dead volume, specially the capillary of the micronebulizer, as well as the optimization of chromatographic conditions led to the claimed advantages expected for microbore columns: a significant diminution of sample and solvent consumption without sacrificing sensitivity and the overall resolution in faster analysis time (less than 5 min). Detection limits are in the range 0.03-0.04 microg L(-1) for arsenic species and 0.35 microg L(-1) for selenium species. The developed method was validated by analysing different spiked environmental water samples. Linearity, tested up to 50 microg L(-1), showed correlation coefficients above 0.999 and no matrix effect for high saline water samples. Good accuracy and repeatability was obtained for spiked influent and effluent water treatment plant.","Capabilities of microbore columns coupled to inductively coupled plasma mass spectrometry in speciation of arsenic and selenium Abs: The performance of microHPLC-microconcentric nebulizer-inductively coupled plasma-mass spectrometry (ICP-MS) coupling for the simultaneous determination of As(III), As(V), monomethylarsenic acid (MMA), dimethylarsinic acid (DMA), selenite (SeIV) and selenate (SeVI) in water was evaluated. The accurate reduction of the off-column dead volume, specially the capillary of the micronebulizer, as well as the optimization of chromatographic conditions led to the claimed advantages expected for microbore columns: a significant diminution of sample and solvent consumption without sacrificing sensitivity and the overall resolution in faster analysis time (less than 5 min). Detection limits are in the range 0.03-0.04 microg L(-1) for arsenic species and 0.35 microg L(-1) for selenium species. The developed method was validated by analysing different spiked environmental water samples. Linearity, tested up to 50 microg L(-1), showed correlation coefficients above 0.999 and no matrix effect for high saline water samples. Good accuracy and repeatability was obtained for spiked influent and effluent water treatment plant."
1030669,Götzl and  Riepe 2001,Field procedures to assess soils and waste disposals,"The aim of this research was the development of rapid analytical test methods for arsenic, lead, cadmium, chromium(VI), copper, nickel, and zinc to classify waste materials into waste classes and assess contaminated soils for purification purposes. In order to estimate the danger potentials of contaminated soils, a rapid ecotoxicological method was developed (A. Götzl, H. Malissa, W. Riepe, FACT 3 (6) (1999) 329.). These rapid analytical and ecotoxicological tests offer an instrument to comprehensively assess soils and wastes. The developed rapid methods are suitable for the elution of different soils and wastes, the analysis of the eluates and also for waste waters with concentrations greater than 0.1 mg l(-1) arsenic, 0.5 mg l(-1) lead, 0.01 mg l(-1) cadmium, 0.1 mg l(-1) chromium(VI), 0.3 mg l(-1) copper, 0.5 mg l(-1) nickel and 0.1 mg l(-1) zinc in the eluate. Our developed rapid analytical test methods described below can be implemented on site, are of low cost and are not time-consuming (about 30 min). They also do not need to be carried out by highly qualified specialists only, they can also be easily applied by persons with some experience. The comparability of results obtained using the developed rapid test method and standardised methods was tested with various matrices.","Field procedures to assess soils and waste disposals Abs: The aim of this research was the development of rapid analytical test methods for arsenic, lead, cadmium, chromium(VI), copper, nickel, and zinc to classify waste materials into waste classes and assess contaminated soils for purification purposes. In order to estimate the danger potentials of contaminated soils, a rapid ecotoxicological method was developed (A. Götzl, H. Malissa, W. Riepe, FACT 3 (6) (1999) 329.). These rapid analytical and ecotoxicological tests offer an instrument to comprehensively assess soils and wastes. The developed rapid methods are suitable for the elution of different soils and wastes, the analysis of the eluates and also for waste waters with concentrations greater than 0.1 mg l(-1) arsenic, 0.5 mg l(-1) lead, 0.01 mg l(-1) cadmium, 0.1 mg l(-1) chromium(VI), 0.3 mg l(-1) copper, 0.5 mg l(-1) nickel and 0.1 mg l(-1) zinc in the eluate. Our developed rapid analytical test methods described below can be implemented on site, are of low cost and are not time-consuming (about 30 min). They also do not need to be carried out by highly qualified specialists only, they can also be easily applied by persons with some experience. The comparability of results obtained using the developed rapid test method and standardised methods was tested with various matrices."
1030183,Kim and  Na 1991,Effect of sodium dichromate on carbohydrate metabolism,"Subcutaneous injection of sodium dichromate into male Sprague-Dawley rats immediately produced a variety of metabolic changes in a dose-dependent manner. Serum lactate and glucose were significantly increased after dichromate treatment, reaching maximum levels at 15 and 30 min, respectively. Then, the toxicity progressively diminished. In contrast, a steady increase in blood urea nitrogen (BUN) concentration was caused by dichromate, reaching maximum levels at 60 min after the administration; elevated BUN levels were sustained for several hours thereafter. Unlike KCN (5 mg/kg, ip) and As2O3 (5 mg/kg, ip), dichromate rapidly decreased serum insulin within 15 min after intoxication in doses of 20 and 40 mg/kg; hypoinsulinemia lasted 60 min. However, insulin levels returned to the normal range at 120 min after treatment. Dichromate-induced metabolic disturbance was also observed in the 24 hr-fasted rats, the response of which was similar to normal rats except for later hyperglycemia. In both cases, the duration time was short (30 to 60 min). Adrenalectomy and insulin pretreatment had no effect on dichromate-induced hyperglycemia. These results suggest that dichromate-induced metabolic disturbance results from the concomitant effects of a sudden decrease in serum insulin level and its direct inhibitory effect on carbohydrate metabolism. In addition, the characteristic biphasic pattern of metabolic disturbance might be related to metabolic fate of dichromate in vivo.","Effect of sodium dichromate on carbohydrate metabolism Abs: Subcutaneous injection of sodium dichromate into male Sprague-Dawley rats immediately produced a variety of metabolic changes in a dose-dependent manner. Serum lactate and glucose were significantly increased after dichromate treatment, reaching maximum levels at 15 and 30 min, respectively. Then, the toxicity progressively diminished. In contrast, a steady increase in blood urea nitrogen (BUN) concentration was caused by dichromate, reaching maximum levels at 60 min after the administration; elevated BUN levels were sustained for several hours thereafter. Unlike KCN (5 mg/kg, ip) and As2O3 (5 mg/kg, ip), dichromate rapidly decreased serum insulin within 15 min after intoxication in doses of 20 and 40 mg/kg; hypoinsulinemia lasted 60 min. However, insulin levels returned to the normal range at 120 min after treatment. Dichromate-induced metabolic disturbance was also observed in the 24 hr-fasted rats, the response of which was similar to normal rats except for later hyperglycemia. In both cases, the duration time was short (30 to 60 min). Adrenalectomy and insulin pretreatment had no effect on dichromate-induced hyperglycemia. These results suggest that dichromate-induced metabolic disturbance results from the concomitant effects of a sudden decrease in serum insulin level and its direct inhibitory effect on carbohydrate metabolism. In addition, the characteristic biphasic pattern of metabolic disturbance might be related to metabolic fate of dichromate in vivo."
1030169,Buhl and  Hamilton 1991,"Relative sensitivity of early life stages of Arctic grayling, Coho salmon, and rainbow trout to nine inorganics","The acute toxicity of nine inorganics associated with placer mining sediments to early life stages of Arctic grayling (Thymallus arcticus), coho salmon (Oncorhynchus kisutch), and rainbow trout (O. mykiss) was determined in soft water (hardness, 41 mg liter-1 CaCO3) at 12 degrees C. The relative toxicities of the inorganics varied by four orders of magnitude; from most toxic to least toxic, the rank order was cadmium, silver, mercury, nickel, gold, arsenite, selenite, selenate, and hexavalent chromium. In general, juvenile life stages of the three species tested were more sensitive to these inorganics than the alevin life stage. Among juveniles, no single species was consistently more sensitive to the inorganics than another; among alevins, Arctic grayling were generally more sensitive than coho salmon and rainbow trout. Based on the results of the present study, estimated no-effect concentrations of arsenic and mercury, but not cadmium, chromium, gold, nickel, selenium, or silver, are close to their concentrations reported in streams with active placer mines in Alaska. Thus, arsenic (as arsenite(III)) and mercury may pose a hazard to Arctic grayling and coho salmon in Alaskan streams with active placer mines.","Relative sensitivity of early life stages of Arctic grayling, Coho salmon, and rainbow trout to nine inorganics Abs: The acute toxicity of nine inorganics associated with placer mining sediments to early life stages of Arctic grayling (Thymallus arcticus), coho salmon (Oncorhynchus kisutch), and rainbow trout (O. mykiss) was determined in soft water (hardness, 41 mg liter-1 CaCO3) at 12 degrees C. The relative toxicities of the inorganics varied by four orders of magnitude; from most toxic to least toxic, the rank order was cadmium, silver, mercury, nickel, gold, arsenite, selenite, selenate, and hexavalent chromium. In general, juvenile life stages of the three species tested were more sensitive to these inorganics than the alevin life stage. Among juveniles, no single species was consistently more sensitive to the inorganics than another; among alevins, Arctic grayling were generally more sensitive than coho salmon and rainbow trout. Based on the results of the present study, estimated no-effect concentrations of arsenic and mercury, but not cadmium, chromium, gold, nickel, selenium, or silver, are close to their concentrations reported in streams with active placer mines in Alaska. Thus, arsenic (as arsenite(III)) and mercury may pose a hazard to Arctic grayling and coho salmon in Alaskan streams with active placer mines."
1029295,Matos et al. 2009,Nephrotoxicity of CCA-treated wood: A comparative study with As(2)O(5) and CrO(3) on mice,"The purpose of this work was to assess the acute toxicity on male mice to a chromated copper arsenate (CCA) solution, a widespread wood preservative used in building industry until 2002. Animals were subcutaneously injected with CCA (7.2mg/kg arsenic and 10.2mg/kg chromium per body weight), CrO(3) (10.2mg/kg), As(2)O(5) (7.2mg/kg) and NaCl (0.9%) per se, during 48h and 96h, for histopathology, histochemistry, chromium and arsenic analysis. The results showed some histopathological changes within renal tubules lumen of CCA exposed animals (during 48h, and 96h), and CrO(3) (for the period of 96h). Furthermore, the renal levels of arsenic and chromium in treated animals were statistically more evident than controls. Although, the same contents of pentavalent arsenic and hexavalent chromium were injected into treated animals with CCA and with the prepared solutions of As(2)O(5) and CrO(3), a different distribution of the pattern of these compounds was observed in kidneys.","Nephrotoxicity of CCA-treated wood: A comparative study with As(2)O(5) and CrO(3) on mice Abs: The purpose of this work was to assess the acute toxicity on male mice to a chromated copper arsenate (CCA) solution, a widespread wood preservative used in building industry until 2002. Animals were subcutaneously injected with CCA (7.2mg/kg arsenic and 10.2mg/kg chromium per body weight), CrO(3) (10.2mg/kg), As(2)O(5) (7.2mg/kg) and NaCl (0.9%) per se, during 48h and 96h, for histopathology, histochemistry, chromium and arsenic analysis. The results showed some histopathological changes within renal tubules lumen of CCA exposed animals (during 48h, and 96h), and CrO(3) (for the period of 96h). Furthermore, the renal levels of arsenic and chromium in treated animals were statistically more evident than controls. Although, the same contents of pentavalent arsenic and hexavalent chromium were injected into treated animals with CCA and with the prepared solutions of As(2)O(5) and CrO(3), a different distribution of the pattern of these compounds was observed in kidneys."
1028965,Stummann et al. 2008,Embryotoxicity hazard assessment of cadmium and arsenic compounds using embryonic stem cells,"The Embryonic Stem Cell Test (EST) has been successfully validated as an in vitro method for detecting embryotoxicity, showing a good overall test accuracy of 78% [Genschow, E., Spielmann, H., Scholz, G., Seiler, A., Brown, N., Piersma, A., Brady, M., Clemann, N., Huuskonen, H., Paillard, F., Bremer, S., Becker, K., 2002. The ECVAM international validation study on in vitro embryotoxicity tests: results of the definitive phase and evaluation of prediction models. European Centre for the Validation of Alternative Methods. Altern. Lab. Anim. 30, 151-176]. Methylmercury was the only strong in vivo embryotoxicant falsely predicted as non-embryotoxic making the metal the most significant outlayer [Genschow, E., Spielmann, H., Scholz, G., Pohl, I., Seiler, A., Clemann, N., Bremer, S., Becker, K., 2004. Validation of the Embryonic Stem Cell Test in the international ECVAM validation study on three in vitro embryotoxicity tests. Altern. Lab. Anim. 32, 209-244]. The misclassification of methylmercury and the potential environmental exposure to developmental toxic heavy metals promoted our investigation of whether the EST applicability domain covers cadmium and arsenic compounds. The EST misclassified cadmium, arsenite and arsenate compounds as non-embryotoxic, even when including arsenic metabolites (methylarsonate, methylarsonous and dimethylarsinic). The reasons were the lack of higher cytotoxicity towards embryonic stem cells as compared to more mature cells (3T3 fibroblasts) or the absence of inhibition of cardiac differentiation by specific mechanisms rather than general cytotoxicity. Including EST data on heavy metals from the literature (lithium, methylmercury, trivalent chromium and hexavalent chromium) revealed that the test correctly predicted the embryotoxic potential of three out of the seven heavy metals, indicating an insufficient predictivity for such metals. Refinement of the EST prediction model and inclusion of additional toxicological endpoints could expand the applicability domain and enhance the predictive power of the test.","Embryotoxicity hazard assessment of cadmium and arsenic compounds using embryonic stem cells Abs: The Embryonic Stem Cell Test (EST) has been successfully validated as an in vitro method for detecting embryotoxicity, showing a good overall test accuracy of 78% [Genschow, E., Spielmann, H., Scholz, G., Seiler, A., Brown, N., Piersma, A., Brady, M., Clemann, N., Huuskonen, H., Paillard, F., Bremer, S., Becker, K., 2002. The ECVAM international validation study on in vitro embryotoxicity tests: results of the definitive phase and evaluation of prediction models. European Centre for the Validation of Alternative Methods. Altern. Lab. Anim. 30, 151-176]. Methylmercury was the only strong in vivo embryotoxicant falsely predicted as non-embryotoxic making the metal the most significant outlayer [Genschow, E., Spielmann, H., Scholz, G., Pohl, I., Seiler, A., Clemann, N., Bremer, S., Becker, K., 2004. Validation of the Embryonic Stem Cell Test in the international ECVAM validation study on three in vitro embryotoxicity tests. Altern. Lab. Anim. 32, 209-244]. The misclassification of methylmercury and the potential environmental exposure to developmental toxic heavy metals promoted our investigation of whether the EST applicability domain covers cadmium and arsenic compounds. The EST misclassified cadmium, arsenite and arsenate compounds as non-embryotoxic, even when including arsenic metabolites (methylarsonate, methylarsonous and dimethylarsinic). The reasons were the lack of higher cytotoxicity towards embryonic stem cells as compared to more mature cells (3T3 fibroblasts) or the absence of inhibition of cardiac differentiation by specific mechanisms rather than general cytotoxicity. Including EST data on heavy metals from the literature (lithium, methylmercury, trivalent chromium and hexavalent chromium) revealed that the test correctly predicted the embryotoxic potential of three out of the seven heavy metals, indicating an insufficient predictivity for such metals. Refinement of the EST prediction model and inclusion of additional toxicological endpoints could expand the applicability domain and enhance the predictive power of the test."
1028696,Biggart and  Costa 1986,Assessment of the uptake and mutagenicity of nickel chloride in salmonella tester strains,"NiCl2 was examined for mutagenic activity in a number of Salmonella tester strains. Conditions were established where there was substantial uptake of the metal into the bacterial cells. However, even when the metal ion was apparently taken up, as determined by metal association with cells, there was a lack of mutagenic activity. These results suggest that nickel is unable to induce basepair or frameshift mutations in Salmonella tester strains and are discussed in relationship to the low binding affinity of Ni(II) for DNA.","Assessment of the uptake and mutagenicity of nickel chloride in salmonella tester strains Abs: NiCl2 was examined for mutagenic activity in a number of Salmonella tester strains. Conditions were established where there was substantial uptake of the metal into the bacterial cells. However, even when the metal ion was apparently taken up, as determined by metal association with cells, there was a lack of mutagenic activity. These results suggest that nickel is unable to induce basepair or frameshift mutations in Salmonella tester strains and are discussed in relationship to the low binding affinity of Ni(II) for DNA."
1028655,Baker et al. 1986,Toxic and genotoxic action of electric-arc welding fumes on cultured mammalian cells,"Welding fumes generated by manual metal arc welding (MMAW) with an automatic welding machine were extracted with water and both the soluble and insoluble fractions were investigated for mitotic delay and for sister chromatid exchange (SCE) induction in cultured Chinese hamster lung (Don) cells. Five flux-coated electrodes of varying composition were chosen as representative of those available. In general, water-soluble and water-insoluble fractions induced SCE in proportion to their chromium(VI) content, and any contribution from chromium(III), fluorides, nickel, manganese or other fume constituents was minor. However, mitotic delay could not be explained in terms of the chromium(VI) concentration alone. This indicated that other components of both the soluble and insoluble fractions of the fumes were capable of inducing mitotic delay. The activity of insoluble fume fractions, either in mitotic delay- or in SCE-induction, was markedly less than that of soluble fractions. This was presumably because of the lower, though still significant, bioavailability of 'insoluble' components of the fume particles.","Toxic and genotoxic action of electric-arc welding fumes on cultured mammalian cells Abs: Welding fumes generated by manual metal arc welding (MMAW) with an automatic welding machine were extracted with water and both the soluble and insoluble fractions were investigated for mitotic delay and for sister chromatid exchange (SCE) induction in cultured Chinese hamster lung (Don) cells. Five flux-coated electrodes of varying composition were chosen as representative of those available. In general, water-soluble and water-insoluble fractions induced SCE in proportion to their chromium(VI) content, and any contribution from chromium(III), fluorides, nickel, manganese or other fume constituents was minor. However, mitotic delay could not be explained in terms of the chromium(VI) concentration alone. This indicated that other components of both the soluble and insoluble fractions of the fumes were capable of inducing mitotic delay. The activity of insoluble fume fractions, either in mitotic delay- or in SCE-induction, was markedly less than that of soluble fractions. This was presumably because of the lower, though still significant, bioavailability of 'insoluble' components of the fume particles."
1028633,Rasmuson 1985,Mutagenic effects of some water-soluble metal compounds in a somatic eye-color test system in Drosophila melanogaster,"Nickel, cadmium, lead, arsenic, manganese and chromium salts as well as MeHgOH were screened for mutagenicity, using a sensitive somatic eye-color test system in Drosophila melanogaster. The test is based on the insertion of a mobile element which causes instability in the white locus that is somatically enhanced by mutagens. This white locus expression is combined with a mutation, zeste, in another gene, to produce a light yellow eye color. Larval feeding with mutagens causes somatic mutations in the eye imaginal disc cells that develop into easily detectable red spots in the yellow eyes of adult males. Survival tests showed large differences in the toxicity of different metals, but only hexavalent chromium increased the frequency of somatic mutations above the control level. When combined treatments were carried out with MMS and various metals, sodium arsenite caused a reduction of the MMS-induced mutation frequency while methylmercury increased the frequency of somatic spots.","Mutagenic effects of some water-soluble metal compounds in a somatic eye-color test system in Drosophila melanogaster Abs: Nickel, cadmium, lead, arsenic, manganese and chromium salts as well as MeHgOH were screened for mutagenicity, using a sensitive somatic eye-color test system in Drosophila melanogaster. The test is based on the insertion of a mobile element which causes instability in the white locus that is somatically enhanced by mutagens. This white locus expression is combined with a mutation, zeste, in another gene, to produce a light yellow eye color. Larval feeding with mutagens causes somatic mutations in the eye imaginal disc cells that develop into easily detectable red spots in the yellow eyes of adult males. Survival tests showed large differences in the toxicity of different metals, but only hexavalent chromium increased the frequency of somatic mutations above the control level. When combined treatments were carried out with MMS and various metals, sodium arsenite caused a reduction of the MMS-induced mutation frequency while methylmercury increased the frequency of somatic spots."
1028625,Alley et al. 2009,The effect of PM10 on human lung fibroblasts,"Asthma diagnoses are increasing nationally with the highest rates in the New England states. Epidemiological studies have suggested a relationship between airborne particulate matter (PM) and severity of an asthma attack. However, because particulate matter, PM, is such a complex mixture, it is difficult to isolate the exacerbating factors. In this paper we investigate the effect of NIST (National Institute of Standards and Technology) and Maine PM and the soluble metals released from the PM on the growth of human lung fibroblasts. While the NIST PM itself had the most pronounced effect on cell survival rates, solutions of metals extracted from the PM also affected cell survival. Treatment of cells with 10, 50, 100 and 200 ug/cm(2) resulted in 84 +/- 13%, 69 +/- 15%, 58 +/- 14% and 58 +/- 16% survival, respectively. Appropriate concentrations of eight acid soluble metals from NIST PM were determined and tested on cells giving 91 +/- 11%, 87 +/- 10%, 72 +/- 18% and 66 +/- 20% survival, respectively. Soluble metals from Maine PM were extracted and mixtures of appropriate concentrations of these metals were used to treat cells, resulting in 88 +/- 5%, 81 +/- 5%, 79 +/- 3% and 57 +/- 9% survival rate. To determine which, if any, of the metals individually affected the cells, Mn, Cu, V and As were used to treat the cells. At the metal concentrations tested, only As and V affected cell survival.","The effect of PM10 on human lung fibroblasts Abs: Asthma diagnoses are increasing nationally with the highest rates in the New England states. Epidemiological studies have suggested a relationship between airborne particulate matter (PM) and severity of an asthma attack. However, because particulate matter, PM, is such a complex mixture, it is difficult to isolate the exacerbating factors. In this paper we investigate the effect of NIST (National Institute of Standards and Technology) and Maine PM and the soluble metals released from the PM on the growth of human lung fibroblasts. While the NIST PM itself had the most pronounced effect on cell survival rates, solutions of metals extracted from the PM also affected cell survival. Treatment of cells with 10, 50, 100 and 200 ug/cm(2) resulted in 84 +/- 13%, 69 +/- 15%, 58 +/- 14% and 58 +/- 16% survival, respectively. Appropriate concentrations of eight acid soluble metals from NIST PM were determined and tested on cells giving 91 +/- 11%, 87 +/- 10%, 72 +/- 18% and 66 +/- 20% survival, respectively. Soluble metals from Maine PM were extracted and mixtures of appropriate concentrations of these metals were used to treat cells, resulting in 88 +/- 5%, 81 +/- 5%, 79 +/- 3% and 57 +/- 9% survival rate. To determine which, if any, of the metals individually affected the cells, Mn, Cu, V and As were used to treat the cells. At the metal concentrations tested, only As and V affected cell survival."
1028566,Matos et al. 2009,Nephrotoxicity effects of the wood preservative chromium copper arsenate on mice: histopathological and quantitative approaches,"Chromium copper arsenate (CCA) was used for the protection of wood building materials until the restriction by EPA in 2002. During a short period of time 14-24h, a comparative nephrotoxicity study was performed regarding the effects of CCA and its compounds per se. Histopathological and histochemical features were correlated with the concentration of the total arsenic and chromium in mice kidney. Animals were subcutaneously injected with CCA (7.2mg/kg arsenic and 10.2mg/kg chromium per body weight), CrO3 (10.2mg/kg), As2O5 (7.2 mg/kg) and NaCl (0.9%) per se. The histopathological examination of the renal sections evidenced acute tubular necrosis in the groups of animals exposed to CCA (in both periods of time). Although the same contents of pentavalent arsenic and hexavalent chromium were injected in treated animals with CCA and with the prepared solutions of As2O5 and CrO3, the arsenic concentration on kidneys of CCA-exposed animals was much higher than those in animals exposed to As2O5 (32- and 28-fold higher at 14 and 24h, respectively). However, the elimination of chromium seems to occur similarly in the kidneys of animals treated with CCA and CrO(3)per se. Interactions among the components of CCA result in a marked decrease of the ability of kidney to eliminate simultaneously both analytes. The nephrotoxicity of CCA was higher than its components per se, evidencing a possible synergetic effect.","Nephrotoxicity effects of the wood preservative chromium copper arsenate on mice: histopathological and quantitative approaches Abs: Chromium copper arsenate (CCA) was used for the protection of wood building materials until the restriction by EPA in 2002. During a short period of time 14-24h, a comparative nephrotoxicity study was performed regarding the effects of CCA and its compounds per se. Histopathological and histochemical features were correlated with the concentration of the total arsenic and chromium in mice kidney. Animals were subcutaneously injected with CCA (7.2mg/kg arsenic and 10.2mg/kg chromium per body weight), CrO3 (10.2mg/kg), As2O5 (7.2 mg/kg) and NaCl (0.9%) per se. The histopathological examination of the renal sections evidenced acute tubular necrosis in the groups of animals exposed to CCA (in both periods of time). Although the same contents of pentavalent arsenic and hexavalent chromium were injected in treated animals with CCA and with the prepared solutions of As2O5 and CrO3, the arsenic concentration on kidneys of CCA-exposed animals was much higher than those in animals exposed to As2O5 (32- and 28-fold higher at 14 and 24h, respectively). However, the elimination of chromium seems to occur similarly in the kidneys of animals treated with CCA and CrO(3)per se. Interactions among the components of CCA result in a marked decrease of the ability of kidney to eliminate simultaneously both analytes. The nephrotoxicity of CCA was higher than its components per se, evidencing a possible synergetic effect."
1028243,Brasch et al. 2000,"Positive nickel patch tests do not intensify positive reactions to adjacent patch tests with dichromate: Results from a double-blind multicentre study of the German Contact Dermatitis Research Group (Deutsche Kontaktallergie-Gruppe, DKG)","The possible interference of neighbouring allergic patch-test reactions is still an open question. In this study, we investigated whether there is a distance-related mutual modification of neighbouring allergic patch-test reactions to nickel sulfate and potassium dichromate. We used a double-blind multicentre study design with randomized attachment of special TRUE Tests with 1, 3 and 7 cm distance between nickel sulfate and potassium dichromate patches. 589 patients with a history of nickel allergy (523 female, 66 male) were tested, with a mean age of 35 years. A log-linear modelling approach was used for statistical assessment of the relation between the distance separating neighbouring patch tests with nickel and dichromate and the reactions to the allergens. Non-reproducibility coefficients were compared by the generalized version of Fisher's exact test for arbitrary 2-dimensional contingency tables. For the left side of the back, virtually no differences (p=0.70) were found in the reaction patterns obtained for the 3 distances separating nickel and dichromate patch tests. On the right side of the back, the number of reactions to dichromate patches with only 1 cm distance from moderate/strong nickel reactions was lower than the number of positive dichromate tests at larger distances from nickel tests (on the border of statistical significance: p= 0.05). Corresponding side-related results were obtained for subgroups of patients with and without a history of atopic dermatitis. The non-reproducibility of reactions to dichromate was not significantly related to the distance between neighbouring tests. Our data argue against a ""spillover"" effect of strong/moderate nickel reactions, but indicate that such reactions may, under certain conditions, attenuate adjacent reactions to an unrelated allergen. In the case of future verification, this will have implications for the interpretation of patch tests.","Positive nickel patch tests do not intensify positive reactions to adjacent patch tests with dichromate: Results from a double-blind multicentre study of the German Contact Dermatitis Research Group (Deutsche Kontaktallergie-Gruppe, DKG) Abs: The possible interference of neighbouring allergic patch-test reactions is still an open question. In this study, we investigated whether there is a distance-related mutual modification of neighbouring allergic patch-test reactions to nickel sulfate and potassium dichromate. We used a double-blind multicentre study design with randomized attachment of special TRUE Tests with 1, 3 and 7 cm distance between nickel sulfate and potassium dichromate patches. 589 patients with a history of nickel allergy (523 female, 66 male) were tested, with a mean age of 35 years. A log-linear modelling approach was used for statistical assessment of the relation between the distance separating neighbouring patch tests with nickel and dichromate and the reactions to the allergens. Non-reproducibility coefficients were compared by the generalized version of Fisher's exact test for arbitrary 2-dimensional contingency tables. For the left side of the back, virtually no differences (p=0.70) were found in the reaction patterns obtained for the 3 distances separating nickel and dichromate patch tests. On the right side of the back, the number of reactions to dichromate patches with only 1 cm distance from moderate/strong nickel reactions was lower than the number of positive dichromate tests at larger distances from nickel tests (on the border of statistical significance: p= 0.05). Corresponding side-related results were obtained for subgroups of patients with and without a history of atopic dermatitis. The non-reproducibility of reactions to dichromate was not significantly related to the distance between neighbouring tests. Our data argue against a ""spillover"" effect of strong/moderate nickel reactions, but indicate that such reactions may, under certain conditions, attenuate adjacent reactions to an unrelated allergen. In the case of future verification, this will have implications for the interpretation of patch tests."
1028239,Francalanci et al. 2000,Multicentre study of allergic contact cheilitis from toothpastes,"The present work reports the results of a multicentre study of toothpaste allergic contact cheilitis (TACC) conducted by GIRDCA (Gruppo Italiano Ricerca Dermatiti da Contatto e Ambientali). The study examined 54 patients with eczematous lesions on the lips, the possible cause of which was suspected to be the use of toothpastes. Patch tests were conducted with a standard series, a specially-targeted series (toothpaste cheilitis series, TCS), and with suspected toothpaste(s). A stop-restart test (SRT) was carried out with these, together with a use test to identify possible alternative products. The TCS produced 17 positive reactions in 13 patients, the most frequent being to spearmint oil. Of the 54 patients, 5 displayed positive reactions only to the TCS. The patch tests with toothpaste produced positive reactions in 11/32 patients, the SRT a positive response in 10/12 cases. The diagnosis of TACC was confirmed in 15/54 patients. Alternative products were identified for 5 patients. In conclusion, the allergens most frequently responsible for TACC were the flavourings, and the additional series proved to be useful in many cases (together with patch tests with toothpastes and the SRT) for correct diagnosis and to initiate effective prevention.","Multicentre study of allergic contact cheilitis from toothpastes Abs: The present work reports the results of a multicentre study of toothpaste allergic contact cheilitis (TACC) conducted by GIRDCA (Gruppo Italiano Ricerca Dermatiti da Contatto e Ambientali). The study examined 54 patients with eczematous lesions on the lips, the possible cause of which was suspected to be the use of toothpastes. Patch tests were conducted with a standard series, a specially-targeted series (toothpaste cheilitis series, TCS), and with suspected toothpaste(s). A stop-restart test (SRT) was carried out with these, together with a use test to identify possible alternative products. The TCS produced 17 positive reactions in 13 patients, the most frequent being to spearmint oil. Of the 54 patients, 5 displayed positive reactions only to the TCS. The patch tests with toothpaste produced positive reactions in 11/32 patients, the SRT a positive response in 10/12 cases. The diagnosis of TACC was confirmed in 15/54 patients. Alternative products were identified for 5 patients. In conclusion, the allergens most frequently responsible for TACC were the flavourings, and the additional series proved to be useful in many cases (together with patch tests with toothpastes and the SRT) for correct diagnosis and to initiate effective prevention."
1028225,Wöhrl et al. 2001,A cream containing the chelator DTPA (diethylenetriaminepenta-acetic acid) can prevent contact allergic reactions to metals,"Chelating agents in protective barrier creams have often been used in the prevention of allergic contact dermatitis to nickel. In a pilot study, we demonstrated the preventive effect of 10% diethylenetriaminepentaacetic acid (DTPA) in an oil-in-water emulsion in nickel-sensitized patients. Now we reproduced these results in a randomized, double-blind study. Additionally, we investigated the efficacy of the barrier cream in other clinically relevant metal allergies. Individuals sensitized to various metals had a significant decrease in positive patch test reactions after pre-treatment with the DTPA-cream: 2.5% nickel sulfate (24/28 positive without pre-treatment versus 1/28 with pre-treatment; p&lt;0.0001), 5% nickel sulfate (30/32 versus 15/32; p=0.0003), 1% cobalt chloride (19/20 versus 6/20; p=0.001) and 5% copper sulfate (13/14 versus 5/14; p=0.02). However, the cream had no protective effect with 1% palladium chloride (17/23 versus 16/23) and with 0.5% potassium dichromate (9/13 versus 7/13). We conclude that the DTPA-cream clearly abrogates positive patch test reactions in nickel-, cobalt- and copper-sensitized subjects and that it may therefore be helpful in the management of allergic contact dermatitis.","A cream containing the chelator DTPA (diethylenetriaminepenta-acetic acid) can prevent contact allergic reactions to metals Abs: Chelating agents in protective barrier creams have often been used in the prevention of allergic contact dermatitis to nickel. In a pilot study, we demonstrated the preventive effect of 10% diethylenetriaminepentaacetic acid (DTPA) in an oil-in-water emulsion in nickel-sensitized patients. Now we reproduced these results in a randomized, double-blind study. Additionally, we investigated the efficacy of the barrier cream in other clinically relevant metal allergies. Individuals sensitized to various metals had a significant decrease in positive patch test reactions after pre-treatment with the DTPA-cream: 2.5% nickel sulfate (24/28 positive without pre-treatment versus 1/28 with pre-treatment; p&lt;0.0001), 5% nickel sulfate (30/32 versus 15/32; p=0.0003), 1% cobalt chloride (19/20 versus 6/20; p=0.001) and 5% copper sulfate (13/14 versus 5/14; p=0.02). However, the cream had no protective effect with 1% palladium chloride (17/23 versus 16/23) and with 0.5% potassium dichromate (9/13 versus 7/13). We conclude that the DTPA-cream clearly abrogates positive patch test reactions in nickel-, cobalt- and copper-sensitized subjects and that it may therefore be helpful in the management of allergic contact dermatitis."
1028123,Ryan et al. 2002,Examination of a vehicle for use with water soluble materials in the murine local lymph node assay,"The murine local lymph node assay (LLNA) is a validated method for identifying skin sensitization hazard. Vehicle choice can influence the sensitization potential of haptens in both the LLNA and in humans, therefore selection of an appropriate vehicle is important. Suggested vehicles for the LLNA include organic solvents and organic-aqueous mixtures. However, due to its high surface tension and poor wetting qualities, water is not recommended and therefore testing aqueous soluble materials can be problematic. The aims of this investigation were to identify a water-based vehicle that possesses better skin wetting properties than water alone, and to assess its performance relative to other solvents in the LLNA using aqueous soluble haptens. The selected wetting agent was the surfactant Pluronic(R) L92 (L92). Concentrations of L92 of up to 50% did not induce positive responses in the LLNA. 1% aqueous L92 was chosen for further examination. Dose-response analyses were performed with dinitrobenzene sulfonic acid (DNBS) and formaldehyde formulated either in water, 1% L92, dimethyl sulfoxide (DMSO) or dimethyl formamide (DMF). Potassium dichromate (PDC) and nickel sulfate were tested in 1% L92, DMSO or DMF. The highest concentration of potassium dichromate was retested in each vehicle and in water to assess the effect of the wetting agent. Estimates of the relative sensitizing potency in each vehicle were determined by calculation of EC3 values (the estimated concentration required to induce a threshold positive response). While DNBS and formaldehyde produced positive responses in all four vehicles, their relative potency varied among the vehicles. The rank ordering of potencies for both materials was, from highest to lowest, DMF &gt; or = DMSO &gt; 1% L92 &gt; water. Compared with water, use of 1% L92 resulted in &gt;2-fold increase in potency for DNBS and &gt;3-fold increase for formaldehyde. PDC was positive in DMF, DMSO and 1% L92. The potency ranking was DMF &gt; or = DMSO &gt; 1% L92. Re-evaluation of 0.5% PDC confirmed that formulations of both DMSO and DMF induced strong proliferative responses, whereas somewhat less proliferation was recorded with the 1% L92 vehicle. PDC in water was without activity. The performance of 1% L92 as a vehicle for nickel sulfate was assessed relative to DMSO and DMF. In DMSO, nickel sulfate produced a stimulation index (SI) &gt;3 at only the highest level. Testing in DMF induced low levels of proliferation, but failed to produce a SI of 3 at any concentration tested. When formulated in 1% L92, nickel sulfate caused a SI of 3 when tested at 2.5%. Based on the results of these experiments, for identification of sensitization hazard of aqueous soluble materials using the LLNA, DMF and DMSO are the preferred vehicles. However, if a test material is not soluble in DMF or DMSO, or if higher test concentrations can be achieved in an aqueous vehicle, then 1% L92 may provide a better alternative to water alone in terms of improved assay performance.","Examination of a vehicle for use with water soluble materials in the murine local lymph node assay Abs: The murine local lymph node assay (LLNA) is a validated method for identifying skin sensitization hazard. Vehicle choice can influence the sensitization potential of haptens in both the LLNA and in humans, therefore selection of an appropriate vehicle is important. Suggested vehicles for the LLNA include organic solvents and organic-aqueous mixtures. However, due to its high surface tension and poor wetting qualities, water is not recommended and therefore testing aqueous soluble materials can be problematic. The aims of this investigation were to identify a water-based vehicle that possesses better skin wetting properties than water alone, and to assess its performance relative to other solvents in the LLNA using aqueous soluble haptens. The selected wetting agent was the surfactant Pluronic(R) L92 (L92). Concentrations of L92 of up to 50% did not induce positive responses in the LLNA. 1% aqueous L92 was chosen for further examination. Dose-response analyses were performed with dinitrobenzene sulfonic acid (DNBS) and formaldehyde formulated either in water, 1% L92, dimethyl sulfoxide (DMSO) or dimethyl formamide (DMF). Potassium dichromate (PDC) and nickel sulfate were tested in 1% L92, DMSO or DMF. The highest concentration of potassium dichromate was retested in each vehicle and in water to assess the effect of the wetting agent. Estimates of the relative sensitizing potency in each vehicle were determined by calculation of EC3 values (the estimated concentration required to induce a threshold positive response). While DNBS and formaldehyde produced positive responses in all four vehicles, their relative potency varied among the vehicles. The rank ordering of potencies for both materials was, from highest to lowest, DMF &gt; or = DMSO &gt; 1% L92 &gt; water. Compared with water, use of 1% L92 resulted in &gt;2-fold increase in potency for DNBS and &gt;3-fold increase for formaldehyde. PDC was positive in DMF, DMSO and 1% L92. The potency ranking was DMF &gt; or = DMSO &gt; 1% L92. Re-evaluation of 0.5% PDC confirmed that formulations of both DMSO and DMF induced strong proliferative responses, whereas somewhat less proliferation was recorded with the 1% L92 vehicle. PDC in water was without activity. The performance of 1% L92 as a vehicle for nickel sulfate was assessed relative to DMSO and DMF. In DMSO, nickel sulfate produced a stimulation index (SI) &gt;3 at only the highest level. Testing in DMF induced low levels of proliferation, but failed to produce a SI of 3 at any concentration tested. When formulated in 1% L92, nickel sulfate caused a SI of 3 when tested at 2.5%. Based on the results of these experiments, for identification of sensitization hazard of aqueous soluble materials using the LLNA, DMF and DMSO are the preferred vehicles. However, if a test material is not soluble in DMF or DMSO, or if higher test concentrations can be achieved in an aqueous vehicle, then 1% L92 may provide a better alternative to water alone in terms of improved assay performance."
1028069,Sijerci? et al. 2003,"Frequency of standard and occupational contact allergens in Tuzla area, Bosnia and Herzegovina: retrospective study","Allergic contact dermatitis is acute or chronic inflammatory skin disease of allergic etiology, which develops as a result of delayed type of hypersensitivity, i.e. type IV reaction according to the Gell and Coombs classification. In the retrospective study, we reviewed medical records of 495 patients diagnosed with allergic contact dermatitis in the 1988-1998 period. The records were obtained from the Cabinet of Allergology of the Department of Dermatology and Venerology, Tuzla University Hospital Center. There were 312 women and 183 men, aged between 18 and 60 years. The patients were divided into 6 groups according to their occupation. Contact sensitization was established in 295 or 59.6% of them. The type and frequency of causative agent in allergic contact dermatitis depended on working environment. Potassium dichromate, a component part of cement, caused positive reaction in 48% of construction workers tested, which was significantly more than in the &quot;other occupation&quot; group, where 14.6% of patients showed positive reaction to potassium dichromate (p&lt;0.001). Formaldehyde, used in leather processing, was the most frequent among the four leading allergens in the group of shoe workers (13.3%), whereas charcoal tar (used in the metal processing) was the most frequent allergen in the group of metal workers (13.9%). Nickel sulfate, potassium dichromate, cobalt chloride, and urushiol were frequent allergens in the &quot;other occupation&quot; group, housewives, and textile workers. The listed allergens are present at large in everyday life as well as in particular occupations.","Frequency of standard and occupational contact allergens in Tuzla area, Bosnia and Herzegovina: retrospective study Abs: Allergic contact dermatitis is acute or chronic inflammatory skin disease of allergic etiology, which develops as a result of delayed type of hypersensitivity, i.e. type IV reaction according to the Gell and Coombs classification. In the retrospective study, we reviewed medical records of 495 patients diagnosed with allergic contact dermatitis in the 1988-1998 period. The records were obtained from the Cabinet of Allergology of the Department of Dermatology and Venerology, Tuzla University Hospital Center. There were 312 women and 183 men, aged between 18 and 60 years. The patients were divided into 6 groups according to their occupation. Contact sensitization was established in 295 or 59.6% of them. The type and frequency of causative agent in allergic contact dermatitis depended on working environment. Potassium dichromate, a component part of cement, caused positive reaction in 48% of construction workers tested, which was significantly more than in the &quot;other occupation&quot; group, where 14.6% of patients showed positive reaction to potassium dichromate (p&lt;0.001). Formaldehyde, used in leather processing, was the most frequent among the four leading allergens in the group of shoe workers (13.3%), whereas charcoal tar (used in the metal processing) was the most frequent allergen in the group of metal workers (13.9%). Nickel sulfate, potassium dichromate, cobalt chloride, and urushiol were frequent allergens in the &quot;other occupation&quot; group, housewives, and textile workers. The listed allergens are present at large in everyday life as well as in particular occupations."
1028026,Sockanathan et al. 2003,Oral lichenoid reaction due to chromate/cobalt in dental prosthesis,,Oral lichenoid reaction due to chromate/cobalt in dental prosthesis Abs: 
1027879,Son et al. 2004,Derivation and study of human epithelial cell lines resistant to killing by chromium trioxide,"CrO3 is cytotoxic for human epithelial 293 kidney cells over a narrow concentration range of approximately 2-8 microM (D50 approximately 3.0 microM); significantly greater toxicity is observed in clonogenic assays (D50 approximately 0.1-1.0 microM). Survival of a small fraction of cells (&lt; or = 0.1%) at CrO3 concentrations between 10(-5) to 10(-3) M, and first-order kinetics of cytotoxicity, rationalized the derivation of a new panel of transformed human epithelial cell lines resistant to cytotoxic concentrations of CrO3 over the range of 5-100 microM. Wild-type and Cr-resistant 293 cell lines display similar morphology under phase microscopy, but wild-type cells grow faster and reach stationary phase sooner than Cr-resistant cells. The Cr-resistant phenotype is stable, and it is specific, since Cr-resistant cells are killed by NiSO4 or by CdCl2 at concentrations equivalent to those that kill wild-type cells. Toxicity analysis curves subjected to target theory suggest that the Cr-resistant cell lines have fewer Cr-sensitive &quot;targets&quot; and have undergone a &quot;loss of function&quot; compared to wild-type cells. This loss of function may be related to significantly lower rates of uptake of Na2(51)CrO4,which correlate inversely with CrO3 concentrations used for the selection and maintenance of the Cr-resistant lines, and to reduced levels of an approximately 96-kDa protein in comparison to wild-type cells. This new panel of Cr-resistant transformed human epithelial kidney cell lines will be useful in comparative studies of genetic resistance and sensitivity to human Cr(VI) toxicity, sulfate transport, and growth control differences between wild-type and Cr-resistant cells.","Derivation and study of human epithelial cell lines resistant to killing by chromium trioxide Abs: CrO3 is cytotoxic for human epithelial 293 kidney cells over a narrow concentration range of approximately 2-8 microM (D50 approximately 3.0 microM); significantly greater toxicity is observed in clonogenic assays (D50 approximately 0.1-1.0 microM). Survival of a small fraction of cells (&lt; or = 0.1%) at CrO3 concentrations between 10(-5) to 10(-3) M, and first-order kinetics of cytotoxicity, rationalized the derivation of a new panel of transformed human epithelial cell lines resistant to cytotoxic concentrations of CrO3 over the range of 5-100 microM. Wild-type and Cr-resistant 293 cell lines display similar morphology under phase microscopy, but wild-type cells grow faster and reach stationary phase sooner than Cr-resistant cells. The Cr-resistant phenotype is stable, and it is specific, since Cr-resistant cells are killed by NiSO4 or by CdCl2 at concentrations equivalent to those that kill wild-type cells. Toxicity analysis curves subjected to target theory suggest that the Cr-resistant cell lines have fewer Cr-sensitive &quot;targets&quot; and have undergone a &quot;loss of function&quot; compared to wild-type cells. This loss of function may be related to significantly lower rates of uptake of Na2(51)CrO4,which correlate inversely with CrO3 concentrations used for the selection and maintenance of the Cr-resistant lines, and to reduced levels of an approximately 96-kDa protein in comparison to wild-type cells. This new panel of Cr-resistant transformed human epithelial kidney cell lines will be useful in comparative studies of genetic resistance and sensitivity to human Cr(VI) toxicity, sulfate transport, and growth control differences between wild-type and Cr-resistant cells."
1027735,Baur et al. 1994,[Bronchopulmonary precancerous conditions and tumors--risk groups from the occupational medicine viewpoint],"Risk groups with regard to bronchopulmonary precancerous and tumor diseases of occupational origin can be deduced from current occupational disease statistics. Most prominent are those working with asbestos. Each year about 250 asbestos-associated bronchial carcinomas and 400 mesotheliomas are recognized and compensated; the tendency is increasing. Because of the long latency time, the frequency peak will probably be reached in about 15 years in spite of the prohibition of asbestos usage. The second place is probably taken by malignomas among the underground uranium mine workers in Thuringia and Saxony (SDAG Wismut). Next come bronchial carcinomas with silicosis (carcinoma in scar tissue) after exposure to chromium(VI) and arsenic compounds as well as various other chemicals and metals. Dose-activity relationships are significant for all occupational carcinogenic agents, as there are also often syncancerogenic influences (especially smoking). From the data on previous loading, high risk groups, for example, among the insulation workers exposed to asbestos or uranium miners in the so-called &quot;wild years&quot;, can be defined. A suitable screening method for the detection of bronchopulmonary tumors in the early stages has not yet been established. Medical checkups for the respective risk groups concentrate on the early X-ray detection of circular foci. As shown by recent studies, cytological sputum diagnosis, (fluorescence) bronchoscopy, and BAL cytology must be employed much more frequently in the high risk groups so that the prognostically more favorable stages of preneoplasm and carcinoma in situ can be detected and possibly treated curatively. These procedures are currently reaching a considerably higher sensitivity with the help of modern molecular biology techniques (e.g. detection of tumor-associated genetic changes and gene products). This contributes to an improvement in surveillance examinations with increasing detection of the curable early forms of tumors. However, only the further development of primary prevention, i.e. the greatest possible minimization or, if possible, total elimination of contact with carcinogenic agents and the consequent control of occupational protection will lead to a drastic reduction in the occupational risk of cancer.","[Bronchopulmonary precancerous conditions and tumors--risk groups from the occupational medicine viewpoint] Abs: Risk groups with regard to bronchopulmonary precancerous and tumor diseases of occupational origin can be deduced from current occupational disease statistics. Most prominent are those working with asbestos. Each year about 250 asbestos-associated bronchial carcinomas and 400 mesotheliomas are recognized and compensated; the tendency is increasing. Because of the long latency time, the frequency peak will probably be reached in about 15 years in spite of the prohibition of asbestos usage. The second place is probably taken by malignomas among the underground uranium mine workers in Thuringia and Saxony (SDAG Wismut). Next come bronchial carcinomas with silicosis (carcinoma in scar tissue) after exposure to chromium(VI) and arsenic compounds as well as various other chemicals and metals. Dose-activity relationships are significant for all occupational carcinogenic agents, as there are also often syncancerogenic influences (especially smoking). From the data on previous loading, high risk groups, for example, among the insulation workers exposed to asbestos or uranium miners in the so-called &quot;wild years&quot;, can be defined. A suitable screening method for the detection of bronchopulmonary tumors in the early stages has not yet been established. Medical checkups for the respective risk groups concentrate on the early X-ray detection of circular foci. As shown by recent studies, cytological sputum diagnosis, (fluorescence) bronchoscopy, and BAL cytology must be employed much more frequently in the high risk groups so that the prognostically more favorable stages of preneoplasm and carcinoma in situ can be detected and possibly treated curatively. These procedures are currently reaching a considerably higher sensitivity with the help of modern molecular biology techniques (e.g. detection of tumor-associated genetic changes and gene products). This contributes to an improvement in surveillance examinations with increasing detection of the curable early forms of tumors. However, only the further development of primary prevention, i.e. the greatest possible minimization or, if possible, total elimination of contact with carcinogenic agents and the consequent control of occupational protection will lead to a drastic reduction in the occupational risk of cancer."
1027627,Carter 1995,Oxidation-reduction reactions of metal ions,"Several metal or metalloid ions exist in multiple oxidation states and can undergo electron transfer reactions that are important in biological and environmental systems. There are endogenous metal ions such as iron, copper, and cobalt that participate in oxidation-reduction reactions with species of oxygen like molecular dioxygen, superoxide, and hydrogen peroxide. These reactions may be modulated by endogenous reducing agents such as glutathione, ascorbate, and tocopherol. The reactions can be described in terms of thermodynamics through the use of standard electrode potentials. A favorable reaction will depend on the concentrations of the reactants and may depend on the pH and/or on the presence of organic ligands that form complexes with the metal or metalloid. Arsenate (As(V)) can react with glutathione in buffered aqueous solutions to produce arsenite (As(III)) and oxidized glutathione. This reaction may be important in the methylation reactions of arsenic. Arsenic species can decrease the red blood cell levels of reduced glutathione, but the products of oxidation and the mechanism of oxidation are more complex than those found in water alone. Chromium (VI) is thought to interact with DNA after first reacting with a reducing agent such as glutathione to form lower oxidation states of chromium. These examples illustrate the importance of oxidation-reduction reactions for toxic metals and metalloids.","Oxidation-reduction reactions of metal ions Abs: Several metal or metalloid ions exist in multiple oxidation states and can undergo electron transfer reactions that are important in biological and environmental systems. There are endogenous metal ions such as iron, copper, and cobalt that participate in oxidation-reduction reactions with species of oxygen like molecular dioxygen, superoxide, and hydrogen peroxide. These reactions may be modulated by endogenous reducing agents such as glutathione, ascorbate, and tocopherol. The reactions can be described in terms of thermodynamics through the use of standard electrode potentials. A favorable reaction will depend on the concentrations of the reactants and may depend on the pH and/or on the presence of organic ligands that form complexes with the metal or metalloid. Arsenate (As(V)) can react with glutathione in buffered aqueous solutions to produce arsenite (As(III)) and oxidized glutathione. This reaction may be important in the methylation reactions of arsenic. Arsenic species can decrease the red blood cell levels of reduced glutathione, but the products of oxidation and the mechanism of oxidation are more complex than those found in water alone. Chromium (VI) is thought to interact with DNA after first reacting with a reducing agent such as glutathione to form lower oxidation states of chromium. These examples illustrate the importance of oxidation-reduction reactions for toxic metals and metalloids."
1027401,Pearce et al. 1910,EXPERIMENTAL ACUTE NEPHRITIS: THE VASCULAR REACTIONS AND THE ELIMINATION OF NITROGEN,"By combining physiological and anatomical methods in the study of experimental nephritis it is possible to distinguish types of nephritis in which either tubular or vascular changes predominate, and are essentially characteristic of the lesion produced, but it is not possible to say that a given poison produces exclusively tubular or exclusively vascular lesions. The so-called epithelial poisons (potassium chromate, uranium nitrate and corrosive sublimate) present anatomical evidence of extensive tubular injury, and in the early stages show, on physiological study, no evidence of vascular injury other than exaggerated contraction and dilatation of the vessels and increased diuresis. On the other hand, the vascular poisons, arsenic and cantharidin, which produce but little injury to the tubules, tend to cause anuria and are characterized by minimal contraction and dilatation of the vessels and little or no flow of urine. From the physiological point of view these two types may be, for practical purposes, considered as examples of tubular and vascular nephritis. They are not, however, pure types; for the increased diuresis of the early tubular type is in itself evidence of vessel irritability and similar to the increased irritability caused by small doses of vascular poisons, and on the other hand, this essentially vascular lesion is accompanied by slight morphological changes in the tubular epithelium. Furthermore, the tubular lesions of chromium and uranium and corrosive sublimate pass into a stage closely resembling the vascular type, if not identical with it. Two forms of late tubular nephritis may be recognized. One of these, the anuric form, is accompanied by severe gastro-intestinal disturbance and evidence of approaching anuria; physiological tests show diminished power of dilatation of the vessels and corresponding inhibition of diuresis. The second form, the polyuric, is characterized by a condition of polyuria up to the moment of anesthesia; physiological tests show that the power of dilatation is retained, but little or no diuresis occurs. Whether the vascular incompetency of the anuric form of late tubular lesions is a natural consequence of the vessel irritability seen in the early stages or is the result of the elimination of secondary poisons through the glomeruli cannot be absolutely determined. The peculiar impermeability of the glomerulus following anesthetization in the polyuric form, which is essentially a stage of recovery, we hope to explain by investigations now in progress. Studies of the elimination of nitrogen show that in tubular nephritis, as represented by uranium nephritis, the output of nitrogen is considerably diminished. This apparently occurs also in chromate nephritis but is not clearly demonstrated. In both forms the onset of gastro-intestinal disturbances appears to bear a definite relation to the retention of nitrogen. On the other hand, as the nitrogen of the feces is not appreciably altered, these disturbances cannot be explained by the elimination through the intestine of toxic bodies of nitrogenous nature. The nitrogen elimination in the urine in vascular nephritis as represented by arsenic nephritis is not only not diminished but is greatly increased as the result of the increased metabolism caused by arsenic. If at the height of this increased elimination, uranium nitrate is administered, the nitrogen output is markedly diminished. These observations demonstrate that not only are the tubular lesions in arsenic nephritis of little moment, but also that serious injury of the epithelium, as that due to uranium, may cause a temporary nitrogen retention. A consideration of all the facts here presented allows us to conclude that although it is not possible to demonstrate that an experimental nephritis may be purely tubular or purely vascular, which is in accord with our clinical and pathological studies of human material, it is possible, if we combine the results of anatomical, physiological and chemical study, to recognize lesions which are predominantly tubular or vascular, or which change rather sharply from one to the other type, and are, therefore, of great value in the study of the problems of nephritis.","EXPERIMENTAL ACUTE NEPHRITIS: THE VASCULAR REACTIONS AND THE ELIMINATION OF NITROGEN Abs: By combining physiological and anatomical methods in the study of experimental nephritis it is possible to distinguish types of nephritis in which either tubular or vascular changes predominate, and are essentially characteristic of the lesion produced, but it is not possible to say that a given poison produces exclusively tubular or exclusively vascular lesions. The so-called epithelial poisons (potassium chromate, uranium nitrate and corrosive sublimate) present anatomical evidence of extensive tubular injury, and in the early stages show, on physiological study, no evidence of vascular injury other than exaggerated contraction and dilatation of the vessels and increased diuresis. On the other hand, the vascular poisons, arsenic and cantharidin, which produce but little injury to the tubules, tend to cause anuria and are characterized by minimal contraction and dilatation of the vessels and little or no flow of urine. From the physiological point of view these two types may be, for practical purposes, considered as examples of tubular and vascular nephritis. They are not, however, pure types; for the increased diuresis of the early tubular type is in itself evidence of vessel irritability and similar to the increased irritability caused by small doses of vascular poisons, and on the other hand, this essentially vascular lesion is accompanied by slight morphological changes in the tubular epithelium. Furthermore, the tubular lesions of chromium and uranium and corrosive sublimate pass into a stage closely resembling the vascular type, if not identical with it. Two forms of late tubular nephritis may be recognized. One of these, the anuric form, is accompanied by severe gastro-intestinal disturbance and evidence of approaching anuria; physiological tests show diminished power of dilatation of the vessels and corresponding inhibition of diuresis. The second form, the polyuric, is characterized by a condition of polyuria up to the moment of anesthesia; physiological tests show that the power of dilatation is retained, but little or no diuresis occurs. Whether the vascular incompetency of the anuric form of late tubular lesions is a natural consequence of the vessel irritability seen in the early stages or is the result of the elimination of secondary poisons through the glomeruli cannot be absolutely determined. The peculiar impermeability of the glomerulus following anesthetization in the polyuric form, which is essentially a stage of recovery, we hope to explain by investigations now in progress. Studies of the elimination of nitrogen show that in tubular nephritis, as represented by uranium nephritis, the output of nitrogen is considerably diminished. This apparently occurs also in chromate nephritis but is not clearly demonstrated. In both forms the onset of gastro-intestinal disturbances appears to bear a definite relation to the retention of nitrogen. On the other hand, as the nitrogen of the feces is not appreciably altered, these disturbances cannot be explained by the elimination through the intestine of toxic bodies of nitrogenous nature. The nitrogen elimination in the urine in vascular nephritis as represented by arsenic nephritis is not only not diminished but is greatly increased as the result of the increased metabolism caused by arsenic. If at the height of this increased elimination, uranium nitrate is administered, the nitrogen output is markedly diminished. These observations demonstrate that not only are the tubular lesions in arsenic nephritis of little moment, but also that serious injury of the epithelium, as that due to uranium, may cause a temporary nitrogen retention. A consideration of all the facts here presented allows us to conclude that although it is not possible to demonstrate that an experimental nephritis may be purely tubular or purely vascular, which is in accord with our clinical and pathological studies of human material, it is possible, if we combine the results of anatomical, physiological and chemical study, to recognize lesions which are predominantly tubular or vascular, or which change rather sharply from one to the other type, and are, therefore, of great value in the study of the problems of nephritis."
1027393,Eisenbrey 1911,A study of the elimination of phenolsulphonephthalein in various experimental lesions of the kidney,"The study of a variety of experimental renal lesions in the dog demonstrates that the phenolsulphonephthalein test of Rowntree and Geraghty is one of the most satisfactory and at the same time most delicate methods of estimating the functional activity of the kidney. The elimination of the test dye is decreased in so-called spontaneous nephritis and in experimental nephritis due to potassium chromate, uranium nitrate, cantharidin, diphtheria toxin, and arsenic, and in those lesions caused by snake venom, hemolytic serum, prolonged renal anemia, and extensive reduction of the kidney substance. Its elimination is not' diminished, but is increased, in the presence of the renal lesion caused by nephrotoxic immune serum, and for this discrepancy no explanation is at hand. The test is a reliable method of demonstrating improvement in the functional activity of the kidney, as is shown in our study of spontaneous nephritis. The increased elimination of the dye occurring after small doses of various irritants, which is frequently characteristic of the early stages of a severe nephritis, and which is seen also several days after unilateral nephrectomy, would appear to have an important relation to the problem of kidney function; and although probably not of clinical importance, it is worthy of further study as a phase of renal activity.","A study of the elimination of phenolsulphonephthalein in various experimental lesions of the kidney Abs: The study of a variety of experimental renal lesions in the dog demonstrates that the phenolsulphonephthalein test of Rowntree and Geraghty is one of the most satisfactory and at the same time most delicate methods of estimating the functional activity of the kidney. The elimination of the test dye is decreased in so-called spontaneous nephritis and in experimental nephritis due to potassium chromate, uranium nitrate, cantharidin, diphtheria toxin, and arsenic, and in those lesions caused by snake venom, hemolytic serum, prolonged renal anemia, and extensive reduction of the kidney substance. Its elimination is not' diminished, but is increased, in the presence of the renal lesion caused by nephrotoxic immune serum, and for this discrepancy no explanation is at hand. The test is a reliable method of demonstrating improvement in the functional activity of the kidney, as is shown in our study of spontaneous nephritis. The increased elimination of the dye occurring after small doses of various irritants, which is frequently characteristic of the early stages of a severe nephritis, and which is seen also several days after unilateral nephrectomy, would appear to have an important relation to the problem of kidney function; and although probably not of clinical importance, it is worthy of further study as a phase of renal activity."
1027364,Goto 1918,"EXPERIMENTAL ACUTE NEPHRITIS : A STUDY OF THE ACIDOSIS, NITROGEN AND CHLORIDE RETENTION, AND OF THE PROTECTIVE ACTION OF SODIUM BICARBONATE","1. In experimental nephritis caused by cantharidin, arsenic, diphtheria toxin, and potassium chromate, in addition to the retention of the non-protein and urea nitrogen and of the chlorides in blood, an acidosis occurs. 2. Sodium bicarbonate given by the stomach has the power of diminishing the acidosis in these types of nephritis. 3. The degree of increase in the non-protein and urea nitrogen content in the blood in mild nephritis varies considerably in different dogs receiving the same dose per kilo of a given poison. 4. Histological examination shows little if any influence resulting from the administration of sodium bicarbonate upon the grade of the nephritis induced by the poisons.","EXPERIMENTAL ACUTE NEPHRITIS : A STUDY OF THE ACIDOSIS, NITROGEN AND CHLORIDE RETENTION, AND OF THE PROTECTIVE ACTION OF SODIUM BICARBONATE Abs: 1. In experimental nephritis caused by cantharidin, arsenic, diphtheria toxin, and potassium chromate, in addition to the retention of the non-protein and urea nitrogen and of the chlorides in blood, an acidosis occurs. 2. Sodium bicarbonate given by the stomach has the power of diminishing the acidosis in these types of nephritis. 3. The degree of increase in the non-protein and urea nitrogen content in the blood in mild nephritis varies considerably in different dogs receiving the same dose per kilo of a given poison. 4. Histological examination shows little if any influence resulting from the administration of sodium bicarbonate upon the grade of the nephritis induced by the poisons."
1027227,Borghesan and  Bellotti 2007,Use of new &quot;barrier socks&quot; in contact allergic dermatitis,"We present the case of a fifty-year-old construction worker with contact allergic dermatitis in his feet. Given the limited results obtained with a costly topical therapy, we tried, for first time, using completely breathable &quot;barrier socks&quot;, which solved the persistent problem in a matter of days. In addition to the improvement in the patient's quality of life and the renewed possibility of his wearing protective shoes, a net reduction in the costs incurred with topical therapy was also obtained.","Use of new &quot;barrier socks&quot; in contact allergic dermatitis Abs: We present the case of a fifty-year-old construction worker with contact allergic dermatitis in his feet. Given the limited results obtained with a costly topical therapy, we tried, for first time, using completely breathable &quot;barrier socks&quot;, which solved the persistent problem in a matter of days. In addition to the improvement in the patient's quality of life and the renewed possibility of his wearing protective shoes, a net reduction in the costs incurred with topical therapy was also obtained."
1027178,Kuykendall et al. 2009,DNA-protein cross-links in erythrocytes of freshwater fish exposed to hexavalent chromium or divalent nickel,"DNA-protein cross-links (DPXs) in fish erythrocytes represent a potential biomarker for exposure to metal cations, such as hexavalent chromium (Cr[VI]) and divalent nickel (Ni[II]). Species-specific sensitivities to DPX formation were studied by coexposure of juvenile specimens of rainbow trout, hybrid bluegill, and channel catfish to waterborne metals, such as Cr(VI) and Ni(II). In a species comparison, 4 days of exposure to 2 ppm Cr(VI) induced highest DPXs in bluegill erythrocytes, followed by trout and catfish, at 186%, 97%, and 48% above controls, respectively. A similar pattern of species sensitivity was observed following co-exposure of the fish to 15 ppm Ni(II) for 4 days, with 237%, 124%, and 82% increased DPXs above control bluegill, trout, and catfish, respectively. Biological stability of Cr(VI)-induced DPXs was demonstrated in Cr(VI)-exposed bluegill, as DPX levels remained elevated for up to 20 days after discontinuation of exposure. Similar results were found following exposure of catfish to Ni(II), with detectable DPXs found 10 days after acute exposure. In both bluegill and catfish, a continued increase in DPX formation in erythrocytes was seen for 5-10 days after Cr(VI) was removed from tank water, suggesting that residual Cr(VI) may be involved in DPX formation following acute exposure of fish.","DNA-protein cross-links in erythrocytes of freshwater fish exposed to hexavalent chromium or divalent nickel Abs: DNA-protein cross-links (DPXs) in fish erythrocytes represent a potential biomarker for exposure to metal cations, such as hexavalent chromium (Cr[VI]) and divalent nickel (Ni[II]). Species-specific sensitivities to DPX formation were studied by coexposure of juvenile specimens of rainbow trout, hybrid bluegill, and channel catfish to waterborne metals, such as Cr(VI) and Ni(II). In a species comparison, 4 days of exposure to 2 ppm Cr(VI) induced highest DPXs in bluegill erythrocytes, followed by trout and catfish, at 186%, 97%, and 48% above controls, respectively. A similar pattern of species sensitivity was observed following co-exposure of the fish to 15 ppm Ni(II) for 4 days, with 237%, 124%, and 82% increased DPXs above control bluegill, trout, and catfish, respectively. Biological stability of Cr(VI)-induced DPXs was demonstrated in Cr(VI)-exposed bluegill, as DPX levels remained elevated for up to 20 days after discontinuation of exposure. Similar results were found following exposure of catfish to Ni(II), with detectable DPXs found 10 days after acute exposure. In both bluegill and catfish, a continued increase in DPX formation in erythrocytes was seen for 5-10 days after Cr(VI) was removed from tank water, suggesting that residual Cr(VI) may be involved in DPX formation following acute exposure of fish."
1027173,Bordel-Gómez et al. 2008,Isolated and concurrent prevalence of sensitization to transition metals in a Spanish population,"<strong>BACKGROUND: </strong>Positive patch test results to transition metals (nickel sulphate, palladium chloride, cobalt chloride and potassium dichromate) alone and in combinations with one another are well known. Numerous factors may play a role in isolated and concurrent sensitization to these allergens.<br /><br /><strong>OBJECTIVE: </strong>This study aims to describe the isolated and concurrent prevalence of sensitization to transition metals in a Spanish Dermatology Department, between 2000 and 2005, and to determine the prevalence of concomitant positive patch test reactions to different transitional metals.<br /><br /><strong>PATIENTS/METHODS: </strong>Patients (N= 1092) were tested with the standard series of our Allergic Contact Unity, using a standardized technique. Data from these patients were recorded on a computer entry form and analysed. Statistical analyses to evaluated associations of metal contact allergy were performed, and we evaluated the concordance among these associations of transition metals.<br /><br /><strong>RESULTS: </strong>Three hundred twenty (29.3%) patients reacted positively to nickel, 128 (11.7%) to palladium, 118 (10.8%) to cobalt and 82 (7.5%) to chromium. The prevalence of positive reactions to metals was 32.4%. The association of palladium-nickel was the most frequent, with an acceptable concordance (k= 0.46).<br /><br /><strong>CONCLUSION: </strong>This study illustrates that concomitant positive patch test reactions to different transitional metals are frequently seen in patients with allergic contact dermatitis. Our results reflect the high prevalence of sensitization to nickel in Spain.","Isolated and concurrent prevalence of sensitization to transition metals in a Spanish population Abs: <strong>BACKGROUND: </strong>Positive patch test results to transition metals (nickel sulphate, palladium chloride, cobalt chloride and potassium dichromate) alone and in combinations with one another are well known. Numerous factors may play a role in isolated and concurrent sensitization to these allergens.<br /><br /><strong>OBJECTIVE: </strong>This study aims to describe the isolated and concurrent prevalence of sensitization to transition metals in a Spanish Dermatology Department, between 2000 and 2005, and to determine the prevalence of concomitant positive patch test reactions to different transitional metals.<br /><br /><strong>PATIENTS/METHODS: </strong>Patients (N= 1092) were tested with the standard series of our Allergic Contact Unity, using a standardized technique. Data from these patients were recorded on a computer entry form and analysed. Statistical analyses to evaluated associations of metal contact allergy were performed, and we evaluated the concordance among these associations of transition metals.<br /><br /><strong>RESULTS: </strong>Three hundred twenty (29.3%) patients reacted positively to nickel, 128 (11.7%) to palladium, 118 (10.8%) to cobalt and 82 (7.5%) to chromium. The prevalence of positive reactions to metals was 32.4%. The association of palladium-nickel was the most frequent, with an acceptable concordance (k= 0.46).<br /><br /><strong>CONCLUSION: </strong>This study illustrates that concomitant positive patch test reactions to different transitional metals are frequently seen in patients with allergic contact dermatitis. Our results reflect the high prevalence of sensitization to nickel in Spain."
1027163,Carlsen et al. 2008,Associations between baseline allergens and polysensitization,"<strong>BACKGROUND: </strong>Identification of patients at risk of developing polysensitization is not possible at present. An association between weak sensitizers and polysensitization has been hypothesized.<br /><br /><strong>OBJECTIVES: </strong>To examine associations of 21 allergens in the European baseline series to polysensitization.<br /><br /><strong>PATIENTS/METHODS: </strong>From a database-based study with 14 998 patients patch tested with the European baseline series between 1985 and 2005, a group of 759 (5.1%) patients were polysensitized. Odds ratios were calculated to determine the relative contribution of each allergen to polysensitization.<br /><br /><strong>RESULTS: </strong>Seven allergens--parabens mix, N-isopropyl-N-phenyl-p-phenylenediamine, sesquiterpene lactone mix, wool alcohols, potassium dichromate, Myroxylon pereirae, and cobalt chloride - showed statistically significant positive associations to polysensitization. Five allergens p-phenylenediamine, neomycin sulfate, epoxy resin, primin, and nickel sulfate showed statistically significant negative associations to polysensitization. For the allergens with the strongest associations, only every second individual with these particular allergies had two or more additional allergies.<br /><br /><strong>CONCLUSIONS: </strong>No common denominator for the association between the allergens and the polysensitization was apparent, and any association, whether positive or negative, was relatively low. Based on these results, sensitization to specific baseline allergens cannot be used as risk indicators for polysensitization.","Associations between baseline allergens and polysensitization Abs: <strong>BACKGROUND: </strong>Identification of patients at risk of developing polysensitization is not possible at present. An association between weak sensitizers and polysensitization has been hypothesized.<br /><br /><strong>OBJECTIVES: </strong>To examine associations of 21 allergens in the European baseline series to polysensitization.<br /><br /><strong>PATIENTS/METHODS: </strong>From a database-based study with 14 998 patients patch tested with the European baseline series between 1985 and 2005, a group of 759 (5.1%) patients were polysensitized. Odds ratios were calculated to determine the relative contribution of each allergen to polysensitization.<br /><br /><strong>RESULTS: </strong>Seven allergens--parabens mix, N-isopropyl-N-phenyl-p-phenylenediamine, sesquiterpene lactone mix, wool alcohols, potassium dichromate, Myroxylon pereirae, and cobalt chloride - showed statistically significant positive associations to polysensitization. Five allergens p-phenylenediamine, neomycin sulfate, epoxy resin, primin, and nickel sulfate showed statistically significant negative associations to polysensitization. For the allergens with the strongest associations, only every second individual with these particular allergies had two or more additional allergies.<br /><br /><strong>CONCLUSIONS: </strong>No common denominator for the association between the allergens and the polysensitization was apparent, and any association, whether positive or negative, was relatively low. Based on these results, sensitization to specific baseline allergens cannot be used as risk indicators for polysensitization."
1027151,Schena et al. 2008,Sensitizing potential of triclosan and triclosan-based skin care products in patients with chronic eczema,"Triclosan is a lypophilic chlorophenol biocide with broad-spectrum antibacterial and antifungal activity. Triclosan-based topical products have been shown to be tolerated and beneficial in atopic dermatitis. The aim of this study was to evaluate the sensitizing potential of triclosan and triclosan-based creams in patients affected by eczematous dermatitis. Two hundred and seventy-five patients affected by chronic eczema (allergic contact dermatitis, irritant contact dermatitis, atopic eczema, nummular eczema, stasis dermatitis) were patch tested with standard patch test series as well as triclosan and triclosan-based products. Standard patch test series resulted positive in 164 patients (61%), with nickel sulfate, house dust mites, fragrance mix, propolis, thimerosal, myroxylon pereira, potassium dichromate, wool alcohols, and p-phenylenediamine the most common sensitizing haptens. Only two patients developed positive reactions to triclosan (0.7%) and four (1.4%) to triclosan-based products. The present study's results confirm that triclosan is well tolerated and has a very low sensitizing potential even in high-risk patients affected by eczema.","Sensitizing potential of triclosan and triclosan-based skin care products in patients with chronic eczema Abs: Triclosan is a lypophilic chlorophenol biocide with broad-spectrum antibacterial and antifungal activity. Triclosan-based topical products have been shown to be tolerated and beneficial in atopic dermatitis. The aim of this study was to evaluate the sensitizing potential of triclosan and triclosan-based creams in patients affected by eczematous dermatitis. Two hundred and seventy-five patients affected by chronic eczema (allergic contact dermatitis, irritant contact dermatitis, atopic eczema, nummular eczema, stasis dermatitis) were patch tested with standard patch test series as well as triclosan and triclosan-based products. Standard patch test series resulted positive in 164 patients (61%), with nickel sulfate, house dust mites, fragrance mix, propolis, thimerosal, myroxylon pereira, potassium dichromate, wool alcohols, and p-phenylenediamine the most common sensitizing haptens. Only two patients developed positive reactions to triclosan (0.7%) and four (1.4%) to triclosan-based products. The present study's results confirm that triclosan is well tolerated and has a very low sensitizing potential even in high-risk patients affected by eczema."
1027126,Collazo et al. 2008,Prevalence of contact allergens in a Hispanic population,"<strong>BACKGROUND: </strong>Patch testing has been used as a screening tool to identify those allergens responsible for the development of allergic contact dermatitis. The objectives of this study were to identify the most common allergens found at the Patch Testing Clinic (PTC) of the Department of Dermatology, Medical Sciences Campus (MSC) University of Puerto Rico (UPR), to correlate patch testing results with demographics and clinical data, and to compare the results with similar studies in other institutions.<br /><br /><strong>METHODS: </strong>A retrospective analysis of the records of patients who underwent patch testing for suspected acute allergic contact dermatitis at the Department of Dermatology of the Medical Sciences Campus of the UPR, from March 31, 2001 to May 31, 2005. Information regarding demographics, medical history, occupation, and test results was retrieved.<br /><br /><strong>RESULTS: </strong>The most common allergens identified were: carba mix, nickel sulphate, thiuram mix, paratertiary butylphenol formaldehyde resin, paraphenylenediamine, and neomycin sulphate. The most commonly affected area was the hands. A correlation was observed between paratertiary butylphenol and involvement of the feet, paraphenylenediamine and generalized dermatitis, and potassium dichromate and occupational exposure.<br /><br /><strong>CONCLUSIONS: </strong>Patch testing remains a worthwhile and quick diagnostic tool for the evaluation of patients with suspected allergic contact dermatitis.","Prevalence of contact allergens in a Hispanic population Abs: <strong>BACKGROUND: </strong>Patch testing has been used as a screening tool to identify those allergens responsible for the development of allergic contact dermatitis. The objectives of this study were to identify the most common allergens found at the Patch Testing Clinic (PTC) of the Department of Dermatology, Medical Sciences Campus (MSC) University of Puerto Rico (UPR), to correlate patch testing results with demographics and clinical data, and to compare the results with similar studies in other institutions.<br /><br /><strong>METHODS: </strong>A retrospective analysis of the records of patients who underwent patch testing for suspected acute allergic contact dermatitis at the Department of Dermatology of the Medical Sciences Campus of the UPR, from March 31, 2001 to May 31, 2005. Information regarding demographics, medical history, occupation, and test results was retrieved.<br /><br /><strong>RESULTS: </strong>The most common allergens identified were: carba mix, nickel sulphate, thiuram mix, paratertiary butylphenol formaldehyde resin, paraphenylenediamine, and neomycin sulphate. The most commonly affected area was the hands. A correlation was observed between paratertiary butylphenol and involvement of the feet, paraphenylenediamine and generalized dermatitis, and potassium dichromate and occupational exposure.<br /><br /><strong>CONCLUSIONS: </strong>Patch testing remains a worthwhile and quick diagnostic tool for the evaluation of patients with suspected allergic contact dermatitis."
1027124,Antonios et al. 2009,Metallic haptens induce differential phenotype of human dendritic cells through activation of mitogen-activated protein kinase and NF-kappaB pathways,"Dendritic cells (DCs) play a major role in the regulation of immune responses to a variety of antigens (Ag) and haptens which participate in the process of DC maturation. Indeed, metallic haptens are able to induce DC maturation in vitro but the mechanism of this maturation is not well understood. We and others have already shown that NiSO(4) activates p38 mitogen-activated protein kinases (p38MAPK), c-jun N-terminal kinase (JNK), extracellular signal-regulated kinase (ERK) and the transcription factor NF-kappaB during the early events of DCs maturation. However, the effect of other metallic haptens on DC maturation is still poorly understood. In the present study, using dendritic cells derived from CD34(+) cord blood cells, we showed that both NiSO(4) and CoCl(2) induced the expression of CD86, CD83, HLA-DR and CD40 and the production of IL-6 in human DCs while K(2)Cr(2)O(7) induced only a slight upregulation of CD86. Interestingly, only NiSO(4) was able to induce the production of IL-12p40. NiSO(4) and CoCl(2) but not K(2)Cr(2)O(7) were able to activate the MAPK pathway and the transcription factor NF-kappaB. The role of MAPKs in metals-induced DC maturation was then evaluated using well-described pharmacological inhibitors. Our results suggest that p38MAPK activation regulates the expression of CD86 and CD83 induced by NiSO(4) while it only affects the expression of CD83 induced by CoCl(2). IL-6 production induced by NiSO(4) and CoCl(2) strongly depended on all MAPKs. IL-12p40 synthesis after NiSO(4) treatment was regulated by both p38MAPK and JNK pathways whereas ERK may play an inhibitory role. Our results show that both NiSO(4) and CoCl(2) activate similar signaling pathways that are playing different roles in DC maturation depending on the hapten used.","Metallic haptens induce differential phenotype of human dendritic cells through activation of mitogen-activated protein kinase and NF-kappaB pathways Abs: Dendritic cells (DCs) play a major role in the regulation of immune responses to a variety of antigens (Ag) and haptens which participate in the process of DC maturation. Indeed, metallic haptens are able to induce DC maturation in vitro but the mechanism of this maturation is not well understood. We and others have already shown that NiSO(4) activates p38 mitogen-activated protein kinases (p38MAPK), c-jun N-terminal kinase (JNK), extracellular signal-regulated kinase (ERK) and the transcription factor NF-kappaB during the early events of DCs maturation. However, the effect of other metallic haptens on DC maturation is still poorly understood. In the present study, using dendritic cells derived from CD34(+) cord blood cells, we showed that both NiSO(4) and CoCl(2) induced the expression of CD86, CD83, HLA-DR and CD40 and the production of IL-6 in human DCs while K(2)Cr(2)O(7) induced only a slight upregulation of CD86. Interestingly, only NiSO(4) was able to induce the production of IL-12p40. NiSO(4) and CoCl(2) but not K(2)Cr(2)O(7) were able to activate the MAPK pathway and the transcription factor NF-kappaB. The role of MAPKs in metals-induced DC maturation was then evaluated using well-described pharmacological inhibitors. Our results suggest that p38MAPK activation regulates the expression of CD86 and CD83 induced by NiSO(4) while it only affects the expression of CD83 induced by CoCl(2). IL-6 production induced by NiSO(4) and CoCl(2) strongly depended on all MAPKs. IL-12p40 synthesis after NiSO(4) treatment was regulated by both p38MAPK and JNK pathways whereas ERK may play an inhibitory role. Our results show that both NiSO(4) and CoCl(2) activate similar signaling pathways that are playing different roles in DC maturation depending on the hapten used."
1027119,Das Gupta et al. 2008,Effect of garlic (Allium sativum) on heavy metal (nickel II and chromium VI) induced alteration of serum lipid profile in male albino rats,"We have studied the effect of simultaneous oral treatment of aqueous garlic extract (Allium sativum) on heavy metal (nickel II and chromium VI) induced changes in serum lipid profile. Nickel sulfate and potassium dichromate treated rats showed a significant increase in serum low density lipoprotein-cholesterol (LDL-C), very low density lipoprotein-cholesterol (VLDL-C) and triglyceride (TG) level as well as decrease in serum high density lipoprotein-cholesterol (HDL-C) level. Simultaneous garlic administration with nickel sulfate showed improvement in serum LDL-C, HDL-C, VLDL-C and TG level. But in case of potassium dichromate, garlic administration did not show satisfactory improvement in lipid profile except VLDL-C and TG level. The results indicate that garlic (Allium sativum) has some beneficial effect in preventing heavy metal (nickel and chromium VI) induced alteration of lipid profile.","Effect of garlic (Allium sativum) on heavy metal (nickel II and chromium VI) induced alteration of serum lipid profile in male albino rats Abs: We have studied the effect of simultaneous oral treatment of aqueous garlic extract (Allium sativum) on heavy metal (nickel II and chromium VI) induced changes in serum lipid profile. Nickel sulfate and potassium dichromate treated rats showed a significant increase in serum low density lipoprotein-cholesterol (LDL-C), very low density lipoprotein-cholesterol (VLDL-C) and triglyceride (TG) level as well as decrease in serum high density lipoprotein-cholesterol (HDL-C) level. Simultaneous garlic administration with nickel sulfate showed improvement in serum LDL-C, HDL-C, VLDL-C and TG level. But in case of potassium dichromate, garlic administration did not show satisfactory improvement in lipid profile except VLDL-C and TG level. The results indicate that garlic (Allium sativum) has some beneficial effect in preventing heavy metal (nickel and chromium VI) induced alteration of lipid profile."
1027101,Jagupilla et al. 2009,Effects of particle size and acid addition on the remediation of chromite ore processing residue using ferrous sulfate,"A bench-scale treatability study was conducted to assess the effects of particle size and acid addition on the remediation of chromite ore processing residue (COPR) using ferrous sulfate. The remediation scheme entailed the chemical reduction of hexavalent chromium [Cr(VI)] and the mitigation of swell potential. Leaching tests and the EQ3/6 geochemical model were used to estimate the acid dosage required to destabilize Cr(VI)-bearing and swell-causing minerals. The model predicted greater acid dosage than that estimated from the batch leaching tests. This indicated that mass transfer limitation may be playing a significant role in impeding the dissolution of COPR minerals following acid addition and hence hindering the remediation of COPR. Cr(VI) concentrations determined by alkaline digestion for the treated samples were less than the current NJDEP standard. However, Cr(VI) concentrations measured by X-ray absorption near edge structure (XANES) were greater than those measured by alkaline digestion. Greater Cr(VI) percentages were reduced for acid pretreated and also for smaller particle size COPR samples. Upon treatment, brownmillerite content was greatly reduced for the acid pretreated samples. Conversely, ettringite, a swell-causing mineral, was not observed in the treated COPR.","Effects of particle size and acid addition on the remediation of chromite ore processing residue using ferrous sulfate Abs: A bench-scale treatability study was conducted to assess the effects of particle size and acid addition on the remediation of chromite ore processing residue (COPR) using ferrous sulfate. The remediation scheme entailed the chemical reduction of hexavalent chromium [Cr(VI)] and the mitigation of swell potential. Leaching tests and the EQ3/6 geochemical model were used to estimate the acid dosage required to destabilize Cr(VI)-bearing and swell-causing minerals. The model predicted greater acid dosage than that estimated from the batch leaching tests. This indicated that mass transfer limitation may be playing a significant role in impeding the dissolution of COPR minerals following acid addition and hence hindering the remediation of COPR. Cr(VI) concentrations determined by alkaline digestion for the treated samples were less than the current NJDEP standard. However, Cr(VI) concentrations measured by X-ray absorption near edge structure (XANES) were greater than those measured by alkaline digestion. Greater Cr(VI) percentages were reduced for acid pretreated and also for smaller particle size COPR samples. Upon treatment, brownmillerite content was greatly reduced for the acid pretreated samples. Conversely, ettringite, a swell-causing mineral, was not observed in the treated COPR."
1027070,An et al. 2009,"Expression of surface markers on the human monocytic leukaemia cell line, THP-1, as indicators for the sensitizing potential of chemicals","<strong>BACKGROUND: </strong>Evaluation of skin sensitization potential is an important part of the safety assessment of cosmetic ingredients and topical drugs. Recently, evaluation of changes in surface marker expression induced in dendritic cells (DC) or DC surrogate cell lines following exposure to chemicals represents one approach for in vitro test methods.<br /><br /><strong>OBJECTIVE: </strong>The study aimed to test the change of expression patterns of surface markers on THP-1 cells by chemicals as a predictive in vitro method for contact sensitization.<br /><br /><strong>METHODS: </strong>We investigated the expression of CD54, CD86, CD83, CD80, and CD40 after a 1-day exposure to sensitizers (1-chloro-2,4-dinitrobenzene; 2,4-dinitrofluorobenzene; benzocaine; 5-chloro-2-methyl-4-isothiazolin-3-one; hexyl cinnamic aldehyde; eugenol; nickel sulfate hexahydrate; potassium dichromate; cobalt sulfate; 2-mercaptobenzothiazole; and ammonium tetrachloroplatinate) and non-sensitizers (sodium lauryl sulfate, benzalkonium chloride, lactic acid, salicylic acid, isopropanol, and dimethyl sulphoxide). The test concentrations were 0.1x, 0.5x, and 1x of the 50% inhibitory concentration, and the relative fluorescence intensity was used as an expression indicator.<br /><br /><strong>RESULT AND CONCLUSION: </strong>By evaluating the expression patterns of CD54, CD86, and CD40, we could classify the chemicals as sensitizers or non-sensitizers, but CD80 and CD83 showed non-specific patterns of expression. These data suggest that the THP-1 cells are good model for screening contact sensitizers and CD40 could be a useful marker complementary to CD54 and CD86.","Expression of surface markers on the human monocytic leukaemia cell line, THP-1, as indicators for the sensitizing potential of chemicals Abs: <strong>BACKGROUND: </strong>Evaluation of skin sensitization potential is an important part of the safety assessment of cosmetic ingredients and topical drugs. Recently, evaluation of changes in surface marker expression induced in dendritic cells (DC) or DC surrogate cell lines following exposure to chemicals represents one approach for in vitro test methods.<br /><br /><strong>OBJECTIVE: </strong>The study aimed to test the change of expression patterns of surface markers on THP-1 cells by chemicals as a predictive in vitro method for contact sensitization.<br /><br /><strong>METHODS: </strong>We investigated the expression of CD54, CD86, CD83, CD80, and CD40 after a 1-day exposure to sensitizers (1-chloro-2,4-dinitrobenzene; 2,4-dinitrofluorobenzene; benzocaine; 5-chloro-2-methyl-4-isothiazolin-3-one; hexyl cinnamic aldehyde; eugenol; nickel sulfate hexahydrate; potassium dichromate; cobalt sulfate; 2-mercaptobenzothiazole; and ammonium tetrachloroplatinate) and non-sensitizers (sodium lauryl sulfate, benzalkonium chloride, lactic acid, salicylic acid, isopropanol, and dimethyl sulphoxide). The test concentrations were 0.1x, 0.5x, and 1x of the 50% inhibitory concentration, and the relative fluorescence intensity was used as an expression indicator.<br /><br /><strong>RESULT AND CONCLUSION: </strong>By evaluating the expression patterns of CD54, CD86, and CD40, we could classify the chemicals as sensitizers or non-sensitizers, but CD80 and CD83 showed non-specific patterns of expression. These data suggest that the THP-1 cells are good model for screening contact sensitizers and CD40 could be a useful marker complementary to CD54 and CD86."
1027067,Theler et al. 2009,Clinical expression of nickel contact dermatitis primed by diagnostic patch test,"<strong>INTRODUCTION: </strong>Persistence of allergen and immunocompetent cells at sites of healed contact dermatitis has been reported. Flare-up reactions triggered by patch testing and after systemic provocation with allergen are well-known phenomena. To our knowledge, we report the first flare-up of a previous patch test site following casual cutaneous application of nickel in an individual with hitherto latent nickel sensitization.<br /><br /><strong>CASE REPORT: </strong>Patch testing in a 23-year-old female patient was performed for dermatitis following application of various gels and adhesive bandages: positive delayed-type hypersensitivity reactions were noted for nickel sulfate and potassium dichromate. The patient had never noticed skin reactions to nickel-containing items before. Three weeks following these patch tests, the patient wore earrings which in the past had been well tolerated. She subsequently developed dermatitis of both earlobes within hours and dermatitis at the site of nickel patch testing within a day.<br /><br /><strong>CONCLUSIONS: </strong>Nickel exposure for 48 h in a patch test is sufficient to induce overt delayed-type hypersensitivity on re-exposure with a previously tolerated antigen in a previously clinically unresponsive individual. Antigen and/or antigen-specific effector cells at the site of previous positive patch testing can be recruited into a delayed-type hypersensitivity reaction for a prolonged period of time.","Clinical expression of nickel contact dermatitis primed by diagnostic patch test Abs: <strong>INTRODUCTION: </strong>Persistence of allergen and immunocompetent cells at sites of healed contact dermatitis has been reported. Flare-up reactions triggered by patch testing and after systemic provocation with allergen are well-known phenomena. To our knowledge, we report the first flare-up of a previous patch test site following casual cutaneous application of nickel in an individual with hitherto latent nickel sensitization.<br /><br /><strong>CASE REPORT: </strong>Patch testing in a 23-year-old female patient was performed for dermatitis following application of various gels and adhesive bandages: positive delayed-type hypersensitivity reactions were noted for nickel sulfate and potassium dichromate. The patient had never noticed skin reactions to nickel-containing items before. Three weeks following these patch tests, the patient wore earrings which in the past had been well tolerated. She subsequently developed dermatitis of both earlobes within hours and dermatitis at the site of nickel patch testing within a day.<br /><br /><strong>CONCLUSIONS: </strong>Nickel exposure for 48 h in a patch test is sufficient to induce overt delayed-type hypersensitivity on re-exposure with a previously tolerated antigen in a previously clinically unresponsive individual. Antigen and/or antigen-specific effector cells at the site of previous positive patch testing can be recruited into a delayed-type hypersensitivity reaction for a prolonged period of time."
1027063,Czarnobilska et al. 2009,Contact hypersensitivity and allergic contact dermatitis among school children and teenagers with eczema,"<strong>BACKGROUND: </strong>Patch testing is an essential procedure in the investigation of eczema in children.<br /><br /><strong>OBJECTIVES: </strong>To analyse the frequency of contact hypersensitivity and allergic contact dermatitis among Polish children with eczema.<br /><br /><strong>PATIENTS/METHODS: </strong>During an allergy screening programme involving 9320 children aged 7 and 16 years, 12.6% reported symptoms of chronic/recurrent eczema. From this group, a representative sample of 229 eczema children underwent patch testing: 96 children aged 7 years and 133 teenagers aged 16 years. Patch testing was with 10 allergens: methylchloroisothiazolinone/methylisothiazolinone (MCI/MI), nickel sulfate, mercury ammonium chloride, thimerosal, cobalt chloride, potassium dichromate, lanolin, fragrance mix I, Myroxylon pereirae (balsam of Peru), and colophonium.<br /><br /><strong>RESULTS: </strong>49.4% tested children were found patch test (PT) positive. 43.8% of 7 year olds with eczema were PT positive, with sensitization to nickel sulfate (30.2%), thimerosal (10.4%), cobalt chloride (8.3%), fragrance mix I (7.3%), MCI/MI (6.3%), potassium dichromate (6.3%), M. pereirae (3.1%), mercury ammonium chloride (2.3%), and colophonium (1.0%). 52.6% teenagers were PT positive, with sensitization to nickel sulfate (23.3%), thimerosal (27.8%), cobalt chloride (10.5%), potassium dichromate (6.0%), mercury ammonium chloride (2.3%), M. pereirae (1.5%), and MCI/MI (0.8%). The final diagnosis of allergic contact dermatitis was confirmed in 36% of 7 year olds and 26% of 16 year olds.<br /><br /><strong>CONCLUSIONS: </strong>Every second child with eczema is PT positive, whereas every third child is finally diagnosed with allergic contact dermatitis.","Contact hypersensitivity and allergic contact dermatitis among school children and teenagers with eczema Abs: <strong>BACKGROUND: </strong>Patch testing is an essential procedure in the investigation of eczema in children.<br /><br /><strong>OBJECTIVES: </strong>To analyse the frequency of contact hypersensitivity and allergic contact dermatitis among Polish children with eczema.<br /><br /><strong>PATIENTS/METHODS: </strong>During an allergy screening programme involving 9320 children aged 7 and 16 years, 12.6% reported symptoms of chronic/recurrent eczema. From this group, a representative sample of 229 eczema children underwent patch testing: 96 children aged 7 years and 133 teenagers aged 16 years. Patch testing was with 10 allergens: methylchloroisothiazolinone/methylisothiazolinone (MCI/MI), nickel sulfate, mercury ammonium chloride, thimerosal, cobalt chloride, potassium dichromate, lanolin, fragrance mix I, Myroxylon pereirae (balsam of Peru), and colophonium.<br /><br /><strong>RESULTS: </strong>49.4% tested children were found patch test (PT) positive. 43.8% of 7 year olds with eczema were PT positive, with sensitization to nickel sulfate (30.2%), thimerosal (10.4%), cobalt chloride (8.3%), fragrance mix I (7.3%), MCI/MI (6.3%), potassium dichromate (6.3%), M. pereirae (3.1%), mercury ammonium chloride (2.3%), and colophonium (1.0%). 52.6% teenagers were PT positive, with sensitization to nickel sulfate (23.3%), thimerosal (27.8%), cobalt chloride (10.5%), potassium dichromate (6.0%), mercury ammonium chloride (2.3%), M. pereirae (1.5%), and MCI/MI (0.8%). The final diagnosis of allergic contact dermatitis was confirmed in 36% of 7 year olds and 26% of 16 year olds.<br /><br /><strong>CONCLUSIONS: </strong>Every second child with eczema is PT positive, whereas every third child is finally diagnosed with allergic contact dermatitis."
1027054,Dickel et al. 2009,Strip patch test vs. conventional patch test: investigation of dose-dependent test sensitivities in nickel- and chromium-sensitive subjects,"<strong>BACKGROUND: </strong>Tape stripping the skin prior to patch testing (strip patch test, SPT) may enhance percutaneous penetration of test substances and increase skin reactivity to test substances.<br /><br /><strong>OBJECTIVE: </strong>To evaluate the test sensitivity of SPT in compliance with our recently presented practical method vs. conventional patch test (PT) in nickel- and dichromate-sensitive subjects.<br /><br /><strong>METHODS: </strong>Thirty subjects participated in the prospective, randomized, controlled, investigator-blind study. Serial dilution tests of nickel sulphate (10,000-50 ppm aq.) and potassium dichromate (1000-5 ppm aq.) were used. Tests were applied in duplicate to both sides of the upper back of the subject, where one, randomly chosen side was tape stripped.<br /><br /><strong>RESULTS: </strong>According to the estimated test sensitivities, SPT is more sensitive than PT in nickel- and dichromate-sensitive subjects, regardless of the interindividual different numbers of tape strips. The superiority of the SPT grows with diminishing concentrations of the allergens.<br /><br /><strong>CONCLUSION: </strong>Test sensitivity of SPT vs. PT is increased. If no positive results are obtained by PT, the SPT could help to detect hidden allergens in case of weak sensitization or low concentration and poor percutaneous penetration of the test substances.","Strip patch test vs. conventional patch test: investigation of dose-dependent test sensitivities in nickel- and chromium-sensitive subjects Abs: <strong>BACKGROUND: </strong>Tape stripping the skin prior to patch testing (strip patch test, SPT) may enhance percutaneous penetration of test substances and increase skin reactivity to test substances.<br /><br /><strong>OBJECTIVE: </strong>To evaluate the test sensitivity of SPT in compliance with our recently presented practical method vs. conventional patch test (PT) in nickel- and dichromate-sensitive subjects.<br /><br /><strong>METHODS: </strong>Thirty subjects participated in the prospective, randomized, controlled, investigator-blind study. Serial dilution tests of nickel sulphate (10,000-50 ppm aq.) and potassium dichromate (1000-5 ppm aq.) were used. Tests were applied in duplicate to both sides of the upper back of the subject, where one, randomly chosen side was tape stripped.<br /><br /><strong>RESULTS: </strong>According to the estimated test sensitivities, SPT is more sensitive than PT in nickel- and dichromate-sensitive subjects, regardless of the interindividual different numbers of tape strips. The superiority of the SPT grows with diminishing concentrations of the allergens.<br /><br /><strong>CONCLUSION: </strong>Test sensitivity of SPT vs. PT is increased. If no positive results are obtained by PT, the SPT could help to detect hidden allergens in case of weak sensitization or low concentration and poor percutaneous penetration of the test substances."
1027053,Zug et al. 2009,Patch-test results of the North American Contact Dermatitis Group 2005-2006,"<strong>BACKGROUND: </strong>The North American Contact Dermatitis Group (NACDG) tests patients who have suspected allergic contact dermatitis with a broad series of screening allergens, and publishes periodic reports of its data.<br /><br /><strong>OBJECTIVE: </strong>To report the NACDG patch-test results from January 1, 2005, to December 31, 2006, and to compare results to pooled test data from the previous 10 years.<br /><br /><strong>METHODS: </strong>Standardized patch testing with 65 allergens was used at 13 centers in North America. Chi-square statistics were utilized for comparisons with previous NACDG data.<br /><br /><strong>RESULTS: </strong>NACDG patch-tested 4,454 patients; 12.3% (557) had an occupation-related skin condition, and 65.3% (2,907) had at least one allergic patch-test reaction. The 15 most frequently positive allergens were nickel sulfate (19.0%), Myroxilon pereirae (balsam of Peru, 11.9%), fragrance mix I (11.5%), quaternium-15 (10.3%), neomycin (10.0%), bacitracin (9.2%), formaldehyde (9.0%), cobalt chloride (8.4%), methyldibromoglutaronitrile/phenoxyethanol (5.8%), p-phenylenediamine (5.0%), potassium dichromate (4.8%), carba mix (3.9%), thiuram mix (3.9%), diazolidinylurea (3.7%), and 2-bromo-2-nitropropane-1,3-diol (3.4%). As compared to the 1994-2004 data, there were significant increases in rates of positivity to nickel, quaternium-15, potassium dichromate, lidocaine, and tea tree oil. Of patch-tested patients, 22.9% (1,019) had a relevant positive reaction to a supplementary allergen; 4.9% (219) had an occupationally relevant positive reaction to a supplementary allergen.<br /><br /><strong>CONCLUSION: </strong>Nickel has been the most frequently positive allergen detected by the NACDG; rates significantly increased in the current study period and most reactions were clinically relevant. Other common allergens were topical antibiotics, preservatives, fragrance mix I and paraphenylenediamine. Testing with an expanded allergen series and supplementary allergens enhances detection of relevant positive allergens.","Patch-test results of the North American Contact Dermatitis Group 2005-2006 Abs: <strong>BACKGROUND: </strong>The North American Contact Dermatitis Group (NACDG) tests patients who have suspected allergic contact dermatitis with a broad series of screening allergens, and publishes periodic reports of its data.<br /><br /><strong>OBJECTIVE: </strong>To report the NACDG patch-test results from January 1, 2005, to December 31, 2006, and to compare results to pooled test data from the previous 10 years.<br /><br /><strong>METHODS: </strong>Standardized patch testing with 65 allergens was used at 13 centers in North America. Chi-square statistics were utilized for comparisons with previous NACDG data.<br /><br /><strong>RESULTS: </strong>NACDG patch-tested 4,454 patients; 12.3% (557) had an occupation-related skin condition, and 65.3% (2,907) had at least one allergic patch-test reaction. The 15 most frequently positive allergens were nickel sulfate (19.0%), Myroxilon pereirae (balsam of Peru, 11.9%), fragrance mix I (11.5%), quaternium-15 (10.3%), neomycin (10.0%), bacitracin (9.2%), formaldehyde (9.0%), cobalt chloride (8.4%), methyldibromoglutaronitrile/phenoxyethanol (5.8%), p-phenylenediamine (5.0%), potassium dichromate (4.8%), carba mix (3.9%), thiuram mix (3.9%), diazolidinylurea (3.7%), and 2-bromo-2-nitropropane-1,3-diol (3.4%). As compared to the 1994-2004 data, there were significant increases in rates of positivity to nickel, quaternium-15, potassium dichromate, lidocaine, and tea tree oil. Of patch-tested patients, 22.9% (1,019) had a relevant positive reaction to a supplementary allergen; 4.9% (219) had an occupationally relevant positive reaction to a supplementary allergen.<br /><br /><strong>CONCLUSION: </strong>Nickel has been the most frequently positive allergen detected by the NACDG; rates significantly increased in the current study period and most reactions were clinically relevant. Other common allergens were topical antibiotics, preservatives, fragrance mix I and paraphenylenediamine. Testing with an expanded allergen series and supplementary allergens enhances detection of relevant positive allergens."
1027037,Goh et al. 1986,Cobalt and nickel content of Asian cements,"The total cobalt and nickel concentration of 11 brands of Asian cement ranged from 8.1 to 14.2 micrograms/g and 14.9 to 28.5 micrograms/g, respectively. These metals exist mainly as insoluble salts; the water-soluble concentration of cobalt and nickel in the cements ranged from 0.39 to 0.65 micrograms/g and from 0-1.2 micrograms/g, respectively. 1.5% (4/272) of construction workers in a prefabrication construction factory had cobalt sensitivity. All had allergic contact dermatitis from chromate in cement. No worker had isolated cobalt sensitivity and cement dermatitis. It appeared that sensitization to cobalt in cement occurs only secondarily to an existing cement dermatitis. 1.8% (5/272) workers had nickel sensitivity: 2 with allergic contact dermatitis to nickel in their watches, 2 were asymptomatic and 1 had allergic contact dermatitis to chromate and cobalt in cement. The low prevalence of cobalt and nickel sensitivity from cement was probably related to the low concentration of soluble cobalt and nickel salts in the cement. However, these insoluble salts can form soluble complexes with body fluids on eczematous skin and sensitize the skin.","Cobalt and nickel content of Asian cements Abs: The total cobalt and nickel concentration of 11 brands of Asian cement ranged from 8.1 to 14.2 micrograms/g and 14.9 to 28.5 micrograms/g, respectively. These metals exist mainly as insoluble salts; the water-soluble concentration of cobalt and nickel in the cements ranged from 0.39 to 0.65 micrograms/g and from 0-1.2 micrograms/g, respectively. 1.5% (4/272) of construction workers in a prefabrication construction factory had cobalt sensitivity. All had allergic contact dermatitis from chromate in cement. No worker had isolated cobalt sensitivity and cement dermatitis. It appeared that sensitization to cobalt in cement occurs only secondarily to an existing cement dermatitis. 1.8% (5/272) workers had nickel sensitivity: 2 with allergic contact dermatitis to nickel in their watches, 2 were asymptomatic and 1 had allergic contact dermatitis to chromate and cobalt in cement. The low prevalence of cobalt and nickel sensitivity from cement was probably related to the low concentration of soluble cobalt and nickel salts in the cement. However, these insoluble salts can form soluble complexes with body fluids on eczematous skin and sensitize the skin."
1027015,Zhou et al. 2009,"Effects of nickel, chromate, and arsenite on histone 3 lysine methylation","Occupational exposure to nickel (Ni), chromium (Cr), and arsenic (As) containing compounds has been associated with lung cancer and other adverse health effects. Their carcinogenic properties may be attributable in part, to activation and/or repression of gene expression induced by changes in the DNA methylation status and histone tail post-translational modifications. Here we show that individual treatment with nickel, chromate, and arsenite all affect the gene activating mark H3K4 methylation. We found that nickel (1 mM), chromate (10 microM), and arsenite (1 microM) significantly increase tri-methyl H3K4 after 24 h exposure in human lung carcinoma A549 cells. Seven days of exposure to lower levels of nickel (50 and 100 microM), chromate (0.5 and 1 microM) or arsenite (0.1, 0.5 and 1 microM) also increased tri-methylated H3K4 in A549 cells. This mark still remained elevated and inherited through cell division 7 days following removal of 1 microM arsenite. We also demonstrate by dual staining immunofluorescence microscopy that both H3K4 tri-methyl and H3K9 di-methyl marks increase globally after 24 h exposure to each metal treatment in A549 cells. However, the tri-methyl H3K4 and di-methyl H3K9 marks localize in different regions in the nucleus of the cell. Thus, our study provides further evidence that a mechanism(s) of carcinogenicity of nickel, chromate, and arsenite metal compounds may involve alterations of various histone tail modifications that may in turn affect the expression of genes that may cause transformation.","Effects of nickel, chromate, and arsenite on histone 3 lysine methylation Abs: Occupational exposure to nickel (Ni), chromium (Cr), and arsenic (As) containing compounds has been associated with lung cancer and other adverse health effects. Their carcinogenic properties may be attributable in part, to activation and/or repression of gene expression induced by changes in the DNA methylation status and histone tail post-translational modifications. Here we show that individual treatment with nickel, chromate, and arsenite all affect the gene activating mark H3K4 methylation. We found that nickel (1 mM), chromate (10 microM), and arsenite (1 microM) significantly increase tri-methyl H3K4 after 24 h exposure in human lung carcinoma A549 cells. Seven days of exposure to lower levels of nickel (50 and 100 microM), chromate (0.5 and 1 microM) or arsenite (0.1, 0.5 and 1 microM) also increased tri-methylated H3K4 in A549 cells. This mark still remained elevated and inherited through cell division 7 days following removal of 1 microM arsenite. We also demonstrate by dual staining immunofluorescence microscopy that both H3K4 tri-methyl and H3K9 di-methyl marks increase globally after 24 h exposure to each metal treatment in A549 cells. However, the tri-methyl H3K4 and di-methyl H3K9 marks localize in different regions in the nucleus of the cell. Thus, our study provides further evidence that a mechanism(s) of carcinogenicity of nickel, chromate, and arsenite metal compounds may involve alterations of various histone tail modifications that may in turn affect the expression of genes that may cause transformation."
1026989,Kleinsasser et al. 2001,Mutagen sensitivity of nasopharyngeal cancer patients,"Primary nasopharyngeal carcinomas (NPCs) may be of various types, including squamous cell carcinomas, undifferentiated carcinomas, and lymphoepitheliomas. Tumor initiation has been linked to the Epstein-Barr virus and, in some geographical regions, to alimentary factors. Possible hereditary components for the appearance of NPCs have not yet been clearly identified. In this study, genetic sensitivity to the genotoxic effects of carcinogenic xenobiotics as an endogenous risk factor of tumor initiation was investigated. The single cell microgel electrophoresis assay was used to quantify chemically-induced DNA damage in lymphocytes of 30 NPC patients and 30 non-tumor donors. The xenobiotics investigated were N'-nitrosodiethylamine, sodium dichromate, and nickel sulphate, with N-methyl-N'-nitro-N-nitrosoguanidine (MNNG) and dimethyl sulfoxide (DMSO) as positive and negative controls, respectively. The extent of DNA migration in the solvent control cultures was not significantly different between the two groups (1.2+/-0.5 mean Olive tail moment and standard deviation of 30 individuals for NPC patients; 1.1+/-0.4 for non-tumor donors). With constant exposure and electrophoretic conditions, genotoxic effects of varying degrees were induced by the different xenobiotics in tumor and non-tumor patients (nickel sulphate: 7.1+/-2.5 for NPC patients and 5.9+/-1.6 for non-tumor donors; sodium dichromate: 18.1+/-5.3 for NPC patients and 16.2+/-5.4 for non-tumor donors; MNNG: 47.8+/-13.3 for NPC patients and 52.7+/-13.6 for non-tumor donors). Only N'-nitrosodiethylamine proved to induce significantly more DNA migration in lymphocytes of tumor patients (9.8+/-3.1) as compared to non-tumor patients (8.2+/-2.3). Although for sodium dichromate the degree of DNA migration did not significantly differ, variability in migration patterns proved to be lower in the tumor group. Mutagen sensitivity of NPC patients was shown to be elevated for a selected xenobiotic, whereas a general elevation of DNA fragility was not present. Further studies on mutagen sensitivity as an endogenous risk factor influencing the susceptibility of patients at the time of first diagnosis of nasopharyngeal carcinomas are warranted.","Mutagen sensitivity of nasopharyngeal cancer patients Abs: Primary nasopharyngeal carcinomas (NPCs) may be of various types, including squamous cell carcinomas, undifferentiated carcinomas, and lymphoepitheliomas. Tumor initiation has been linked to the Epstein-Barr virus and, in some geographical regions, to alimentary factors. Possible hereditary components for the appearance of NPCs have not yet been clearly identified. In this study, genetic sensitivity to the genotoxic effects of carcinogenic xenobiotics as an endogenous risk factor of tumor initiation was investigated. The single cell microgel electrophoresis assay was used to quantify chemically-induced DNA damage in lymphocytes of 30 NPC patients and 30 non-tumor donors. The xenobiotics investigated were N'-nitrosodiethylamine, sodium dichromate, and nickel sulphate, with N-methyl-N'-nitro-N-nitrosoguanidine (MNNG) and dimethyl sulfoxide (DMSO) as positive and negative controls, respectively. The extent of DNA migration in the solvent control cultures was not significantly different between the two groups (1.2+/-0.5 mean Olive tail moment and standard deviation of 30 individuals for NPC patients; 1.1+/-0.4 for non-tumor donors). With constant exposure and electrophoretic conditions, genotoxic effects of varying degrees were induced by the different xenobiotics in tumor and non-tumor patients (nickel sulphate: 7.1+/-2.5 for NPC patients and 5.9+/-1.6 for non-tumor donors; sodium dichromate: 18.1+/-5.3 for NPC patients and 16.2+/-5.4 for non-tumor donors; MNNG: 47.8+/-13.3 for NPC patients and 52.7+/-13.6 for non-tumor donors). Only N'-nitrosodiethylamine proved to induce significantly more DNA migration in lymphocytes of tumor patients (9.8+/-3.1) as compared to non-tumor patients (8.2+/-2.3). Although for sodium dichromate the degree of DNA migration did not significantly differ, variability in migration patterns proved to be lower in the tumor group. Mutagen sensitivity of NPC patients was shown to be elevated for a selected xenobiotic, whereas a general elevation of DNA fragility was not present. Further studies on mutagen sensitivity as an endogenous risk factor influencing the susceptibility of patients at the time of first diagnosis of nasopharyngeal carcinomas are warranted."
1026962,Deng et al. 2006,Nickel potentiates the genotoxic effect of benzo[a]pyrene in Chinese hamster lung V79 cells,"The modulating effect of acute exposure to NiCl2 on the induction of chromosome aberrations by a model carcinogen, benzo[a]pyrene (B[a]P), was examined in Chinese hamster V79 lung cells. At concentrations up to 20 microg/ml (84.2 microM), NiCl2 did not significantly increase the frequency of chromosome aberrations in V79 cells when the cells were exposed concomitantly to 0.5 microg/ml B[a]P. Addition of the S15 liver microsomal fraction together with the B[a]P did not alter the results. Addition of NiCl2 2 hr before treatment of cells with 0.5 microg/ml B[a]P also did not result in a significant elevation of the frequency of chromosome aberrations, even at NiCl2 concentrations as high as 20 microg/ml. Contrasting sharply with these findings, when V79 cells were treated with NiCl2 immediately after B[a]P exposure, a significant increase in the frequency of chromosome damage was observed at NiCl2 concentrations as low as 5 microg/ml (21.1 microM). NiCl2-mediated enhancement of chromosome damage was also observed when V79 cells were exposed to the reactive B[a]P intermediate, benzo[a]pyrene-r-7,t-8-dihydrodiol-t-9,10-epoxide (BPDE). In the BPDE-treated cells, the level of NiCl2-mediated enhancement was similar to that observed with the tumor promoter 12-o-tetradecanoylphorbol-13-acetate (TPA, 100 ng/ml). These results are consistent with the view that the effect of nickel (II) on B[a]P-induced genetic damage is dependent on the relative times of exposure to Ni2+ and B[a]P. NiCl2 did not enhance the frequency of chromosome aberrations induced by Chromium (VI), regardless of the order of addition of the chemicals to the V79 cells. These results suggest that nickel may act as a promoter of chemically-induced genetic damage through induction of error-prone repair.","Nickel potentiates the genotoxic effect of benzo[a]pyrene in Chinese hamster lung V79 cells Abs: The modulating effect of acute exposure to NiCl2 on the induction of chromosome aberrations by a model carcinogen, benzo[a]pyrene (B[a]P), was examined in Chinese hamster V79 lung cells. At concentrations up to 20 microg/ml (84.2 microM), NiCl2 did not significantly increase the frequency of chromosome aberrations in V79 cells when the cells were exposed concomitantly to 0.5 microg/ml B[a]P. Addition of the S15 liver microsomal fraction together with the B[a]P did not alter the results. Addition of NiCl2 2 hr before treatment of cells with 0.5 microg/ml B[a]P also did not result in a significant elevation of the frequency of chromosome aberrations, even at NiCl2 concentrations as high as 20 microg/ml. Contrasting sharply with these findings, when V79 cells were treated with NiCl2 immediately after B[a]P exposure, a significant increase in the frequency of chromosome damage was observed at NiCl2 concentrations as low as 5 microg/ml (21.1 microM). NiCl2-mediated enhancement of chromosome damage was also observed when V79 cells were exposed to the reactive B[a]P intermediate, benzo[a]pyrene-r-7,t-8-dihydrodiol-t-9,10-epoxide (BPDE). In the BPDE-treated cells, the level of NiCl2-mediated enhancement was similar to that observed with the tumor promoter 12-o-tetradecanoylphorbol-13-acetate (TPA, 100 ng/ml). These results are consistent with the view that the effect of nickel (II) on B[a]P-induced genetic damage is dependent on the relative times of exposure to Ni2+ and B[a]P. NiCl2 did not enhance the frequency of chromosome aberrations induced by Chromium (VI), regardless of the order of addition of the chemicals to the V79 cells. These results suggest that nickel may act as a promoter of chemically-induced genetic damage through induction of error-prone repair."
1026939,Nguyen et al. 2008,Prevalence of patch test results from 1970 to 2002 in a multi-centre population in North America (NACDG),"<strong>BACKGROUND: </strong>The North American Contact Dermatitis Group (NACDG) has members who assess subjects with suspected allergic contact dermatitis (ACD) and patch tests them with the same screening allergens using a standardized procedure permitting analysis of long-term trends in patch test reactions.<br /><br /><strong>OBJECTIVE: </strong>This study reports the trends in prevalence patch test positivity of allergens by pooling data collected by the NACDG between 1970 and 2002.<br /><br /><strong>PATIENTS/METHODS: </strong>Patients were tested with the screening series of allergens, using a standardized technique. Data from these patients were recorded on a standard computer entry form and analysed. More than 100 allergens were tested on over 34,000 patients during several patch studies between the period. The Cochran-Armitage test of trend is used to evaluate changes in prevalence over time.<br /><br /><strong>RESULTS: </strong>4 trends are noticed: (1) The incidence of presumed allergic nickel (P &lt; 0.0001) and quaternium-15 (P &lt; 0.0001) reactions rose with consistency over the years. (2) While that of cinnamic aldehyde (P = 0.21) and p-phenylenediamine (P &lt; 0.0001) decreased. (3) The prevalence of positive reactions for potassium dichromate (P &lt; 0.0001) shows an initial steady decrease but then a sharp increase starting from the 1996 period. (4) In contrast, thiuram (P = 0.0008) and neomycin (P &lt; 0.0001) show an initial general increase, with a sharp decrease between 1998 and 2002.<br /><br /><strong>CONCLUSION: </strong>Implications for opportunities to prevent ACD by utilizing less-allergenic alternatives appear robust; however, we do not wish to over generalize interpretations because of important limitations.","Prevalence of patch test results from 1970 to 2002 in a multi-centre population in North America (NACDG) Abs: <strong>BACKGROUND: </strong>The North American Contact Dermatitis Group (NACDG) has members who assess subjects with suspected allergic contact dermatitis (ACD) and patch tests them with the same screening allergens using a standardized procedure permitting analysis of long-term trends in patch test reactions.<br /><br /><strong>OBJECTIVE: </strong>This study reports the trends in prevalence patch test positivity of allergens by pooling data collected by the NACDG between 1970 and 2002.<br /><br /><strong>PATIENTS/METHODS: </strong>Patients were tested with the screening series of allergens, using a standardized technique. Data from these patients were recorded on a standard computer entry form and analysed. More than 100 allergens were tested on over 34,000 patients during several patch studies between the period. The Cochran-Armitage test of trend is used to evaluate changes in prevalence over time.<br /><br /><strong>RESULTS: </strong>4 trends are noticed: (1) The incidence of presumed allergic nickel (P &lt; 0.0001) and quaternium-15 (P &lt; 0.0001) reactions rose with consistency over the years. (2) While that of cinnamic aldehyde (P = 0.21) and p-phenylenediamine (P &lt; 0.0001) decreased. (3) The prevalence of positive reactions for potassium dichromate (P &lt; 0.0001) shows an initial steady decrease but then a sharp increase starting from the 1996 period. (4) In contrast, thiuram (P = 0.0008) and neomycin (P &lt; 0.0001) show an initial general increase, with a sharp decrease between 1998 and 2002.<br /><br /><strong>CONCLUSION: </strong>Implications for opportunities to prevent ACD by utilizing less-allergenic alternatives appear robust; however, we do not wish to over generalize interpretations because of important limitations."
1026902,Cammarota et al. 2006,Matrix metalloproteinases and their inhibitors as biomarkers for metal toxicity in vitro,"Exposure to nickel and chromium, and their compounds, has been associated with adverse health effects. These metals are two human carcinogens whose pathogenesis involves active extracellular matrix degradation and remodelling. In this work we have compared the effects of in vitro exposure to nickel and chromium of a keratinocyte cell line (HaCat). The modulation of matrix metalloproteinase genes was used as biomarker of chemical damage. Confluent cells were constantly exposed to subtoxic chromium and nickel concentrations (10(-5) and 10(-7)M) up to 72 h. Total RNA was extracted and specific matrix metalloproteinase, and inhibitor, gene expression was analyzed by RT-PCR. Moreover, cell cycle alterations were evaluated by flow cytometry. Nickel and chromium showed different results, with an upregulation of MMP-2 mRNA production in nickel-treated cells while chromium exposure down-regulated MMP-2 mRNA production. This result could be correlated to the precocious (6h) over-expression of tissue inhibitor-1 (TIMP-1) mRNA in chromium-treated cells. Cell cycle analysis showed and increase of cells with 4N DNA. These results could be explained as a survival response of cells that escape metal induced apoptosis through the anti-apoptotic effects of TIMP-1. These cells that encompass the genotoxic insult may have a selective proliferation advantage, and therefore represent the precursor pool from which degenerating variants may emerge. To study if the chemical damage was reversible, subconfluent cells were stimulated only for 24 h, then the medium was replaced without metal. Cells were able to recover from nickel exposure, showing only weak alterations in specific mRNA expression and cell cycle alteration respect to control. Chromium-induced damage was irreversible. Our results demonstrated that there is an association between metal toxicity and expression of MMPs and their inhibitors. These biomarkers could be potentially useful to elaborate a prediction model of chemical toxicity.","Matrix metalloproteinases and their inhibitors as biomarkers for metal toxicity in vitro Abs: Exposure to nickel and chromium, and their compounds, has been associated with adverse health effects. These metals are two human carcinogens whose pathogenesis involves active extracellular matrix degradation and remodelling. In this work we have compared the effects of in vitro exposure to nickel and chromium of a keratinocyte cell line (HaCat). The modulation of matrix metalloproteinase genes was used as biomarker of chemical damage. Confluent cells were constantly exposed to subtoxic chromium and nickel concentrations (10(-5) and 10(-7)M) up to 72 h. Total RNA was extracted and specific matrix metalloproteinase, and inhibitor, gene expression was analyzed by RT-PCR. Moreover, cell cycle alterations were evaluated by flow cytometry. Nickel and chromium showed different results, with an upregulation of MMP-2 mRNA production in nickel-treated cells while chromium exposure down-regulated MMP-2 mRNA production. This result could be correlated to the precocious (6h) over-expression of tissue inhibitor-1 (TIMP-1) mRNA in chromium-treated cells. Cell cycle analysis showed and increase of cells with 4N DNA. These results could be explained as a survival response of cells that escape metal induced apoptosis through the anti-apoptotic effects of TIMP-1. These cells that encompass the genotoxic insult may have a selective proliferation advantage, and therefore represent the precursor pool from which degenerating variants may emerge. To study if the chemical damage was reversible, subconfluent cells were stimulated only for 24 h, then the medium was replaced without metal. Cells were able to recover from nickel exposure, showing only weak alterations in specific mRNA expression and cell cycle alteration respect to control. Chromium-induced damage was irreversible. Our results demonstrated that there is an association between metal toxicity and expression of MMPs and their inhibitors. These biomarkers could be potentially useful to elaborate a prediction model of chemical toxicity."
1026889,Kashani et al. 2005,Allergic contact dermatitis in Iran,"The frequency of sensitization to contact allergens varies in different countries because of both genetic and, more importantly, allergen exposure variations. The objective is to determine the frequency of sensitization to contact allergens in Iranian patients with dermatitis. 250 patients with a clinical diagnosis of contact dermatitis and/or atopic dermatitis were evaluated with a 28-allergen screening series recommended by the German Contact Dermatitis Research Group from September 2002 to April 2004 in Tehran, Iran. The patches were applied on the back of the patients, removed after 24 hr and the readings were taken on 24 hr, 48 hr and 72 hr after application. 126 patients (50.4%) showed at least 1 positive reaction, and 23 patients (9.2%) had more than 2 positive reactions. 189 (84.4%) of 224 positive reactions had past and/or present clinical relevance. The 5 most common allergens were nickel sulfate 70 (28.0%), cobalt chloride 32 (12.8%), para-tertiarybutyl phenol formaldehyde resin 20 (8.0%), potassium dichromate 13 (5.2%) and colophony 13 (5.2%). Contact allergy to nickel sulfate was significantly more common in female patients and in patients under 40 years of age (P &lt; 0.05). Nickel sulfate is the most common contact allergen in Iran, mostly affecting women and younger patients probably because of more exposure.","Allergic contact dermatitis in Iran Abs: The frequency of sensitization to contact allergens varies in different countries because of both genetic and, more importantly, allergen exposure variations. The objective is to determine the frequency of sensitization to contact allergens in Iranian patients with dermatitis. 250 patients with a clinical diagnosis of contact dermatitis and/or atopic dermatitis were evaluated with a 28-allergen screening series recommended by the German Contact Dermatitis Research Group from September 2002 to April 2004 in Tehran, Iran. The patches were applied on the back of the patients, removed after 24 hr and the readings were taken on 24 hr, 48 hr and 72 hr after application. 126 patients (50.4%) showed at least 1 positive reaction, and 23 patients (9.2%) had more than 2 positive reactions. 189 (84.4%) of 224 positive reactions had past and/or present clinical relevance. The 5 most common allergens were nickel sulfate 70 (28.0%), cobalt chloride 32 (12.8%), para-tertiarybutyl phenol formaldehyde resin 20 (8.0%), potassium dichromate 13 (5.2%) and colophony 13 (5.2%). Contact allergy to nickel sulfate was significantly more common in female patients and in patients under 40 years of age (P &lt; 0.05). Nickel sulfate is the most common contact allergen in Iran, mostly affecting women and younger patients probably because of more exposure."
1026881,Menezes et al. 2004,Hypersensitivity to metals in orthodontics,"To study the incidence of hypersensitivity to orthodontic metals, patch tests were carried out before and 2 months after the placement of orthodontic appliances in 38 patients (17 male, 21 female). The tested substances were cobalt chloride, copper sulfate, potassium dichromate, iron sulfate, manganese chloride, molybdenum salt, nickel sulfate, and titanium oxide. Eight strips containing the test substances were positioned on the patients' backs. They were removed after 48 hours and assessed by a dermatologist at 48 and 72 hours after antigen application. The obtained data were analyzed by the chi-square test and McNemar's chi-square test. Statistically significant positive reactions were observed for nickel sulfate (21.1%), potassium dichromate (21.1%), and manganese chloride (7.9%); reactions to nickel sulfate had the greatest intensity. No differences were observed between the reactions before and after placement of the orthodontic appliances; this indicates that they did not sensitize the patients or affect their tolerance to these metals during the study period. No statistical difference was observed regarding sex for any evaluated substance, although a greater tendency to positivity to nickel sulfate was observed among female patients and to potassium dichromate in male patients.","Hypersensitivity to metals in orthodontics Abs: To study the incidence of hypersensitivity to orthodontic metals, patch tests were carried out before and 2 months after the placement of orthodontic appliances in 38 patients (17 male, 21 female). The tested substances were cobalt chloride, copper sulfate, potassium dichromate, iron sulfate, manganese chloride, molybdenum salt, nickel sulfate, and titanium oxide. Eight strips containing the test substances were positioned on the patients' backs. They were removed after 48 hours and assessed by a dermatologist at 48 and 72 hours after antigen application. The obtained data were analyzed by the chi-square test and McNemar's chi-square test. Statistically significant positive reactions were observed for nickel sulfate (21.1%), potassium dichromate (21.1%), and manganese chloride (7.9%); reactions to nickel sulfate had the greatest intensity. No differences were observed between the reactions before and after placement of the orthodontic appliances; this indicates that they did not sensitize the patients or affect their tolerance to these metals during the study period. No statistical difference was observed regarding sex for any evaluated substance, although a greater tendency to positivity to nickel sulfate was observed among female patients and to potassium dichromate in male patients."
1026865,Dickel et al. 2002,Occupational relevance of positive standard patch-test results in employed persons with an initial report of an occupational skin disease,"<strong>OBJECTIVES: </strong>It is commonly accepted that the standard screening tray is an essential diagnostic test in patch testing supporting the diagnosis of contact dermatitis, the most common type of occupational skin disease (OSD). In this study standard patch-test results of employed persons with an initial report of an OSD were analyzed within 24 occupational groups.<br /><br /><strong>METHODS: </strong>An evaluation was made of employed persons recorded in the Register of Occupational Skin Diseases in Northern Bavaria (Berufskrankheitenregister Haut-Nordbayern; BKH-N) between 1990 and 1999, catering for those standard screening tray allergens tested over the 10-year period.<br /><br /><strong>RESULTS: </strong>Nickel sulfate was the most common sensitizer (29.5%), showing occupational relevance in only 11% of the cases sensitized. Other common sensitizers were cobalt chloride (13.5%), p-phenylenediamine free base (10.7%), potassium dichromate (9.8%), fragrance mix (5.4%), thiuram mix (4.2%), balsam of Peru (4.0%), chloromethylisothiazolinone/methylisothiazolinone (4.0%), and formaldehyde (4.0%). The most occupationally relevant sensitizers were thiuram mix (71%), epoxy resin (67%), p-phenylenediamine free base (59%), p-phenylenediamine-black-rubber mix/ N-isopropyl- N'-phenyl- p-phenylenediamine (53%), potassium dichromate (48%), formaldehyde (38%), chloromethylisothiazolinone/methylisothiazolinone (37%), and mercapto-mix/mercaptobenzothiazole (35%). Occupational groups at risk of acquiring delayed-type sensitization were, in particular, electroplaters, tile setters and terrazzo workers, construction and cement workers, solderers, wood processors, and leather and fur processors.<br /><br /><strong>CONCLUSIONS: </strong>The standard series contributes valuable information and asserts its position in clarifying the causes of OSDs. Based on the study results, the rate of occupationally relevant sensitization to each single allergen is demonstrated, and the difficulties in verifying the occupational relevance are discussed.","Occupational relevance of positive standard patch-test results in employed persons with an initial report of an occupational skin disease Abs: <strong>OBJECTIVES: </strong>It is commonly accepted that the standard screening tray is an essential diagnostic test in patch testing supporting the diagnosis of contact dermatitis, the most common type of occupational skin disease (OSD). In this study standard patch-test results of employed persons with an initial report of an OSD were analyzed within 24 occupational groups.<br /><br /><strong>METHODS: </strong>An evaluation was made of employed persons recorded in the Register of Occupational Skin Diseases in Northern Bavaria (Berufskrankheitenregister Haut-Nordbayern; BKH-N) between 1990 and 1999, catering for those standard screening tray allergens tested over the 10-year period.<br /><br /><strong>RESULTS: </strong>Nickel sulfate was the most common sensitizer (29.5%), showing occupational relevance in only 11% of the cases sensitized. Other common sensitizers were cobalt chloride (13.5%), p-phenylenediamine free base (10.7%), potassium dichromate (9.8%), fragrance mix (5.4%), thiuram mix (4.2%), balsam of Peru (4.0%), chloromethylisothiazolinone/methylisothiazolinone (4.0%), and formaldehyde (4.0%). The most occupationally relevant sensitizers were thiuram mix (71%), epoxy resin (67%), p-phenylenediamine free base (59%), p-phenylenediamine-black-rubber mix/ N-isopropyl- N'-phenyl- p-phenylenediamine (53%), potassium dichromate (48%), formaldehyde (38%), chloromethylisothiazolinone/methylisothiazolinone (37%), and mercapto-mix/mercaptobenzothiazole (35%). Occupational groups at risk of acquiring delayed-type sensitization were, in particular, electroplaters, tile setters and terrazzo workers, construction and cement workers, solderers, wood processors, and leather and fur processors.<br /><br /><strong>CONCLUSIONS: </strong>The standard series contributes valuable information and asserts its position in clarifying the causes of OSDs. Based on the study results, the rate of occupationally relevant sensitization to each single allergen is demonstrated, and the difficulties in verifying the occupational relevance are discussed."
1026863,Akasya-Hillenbrand and  Ozkaya-Bayazit 2002,Patch test results in 542 patients with suspected contact dermatitis in Turkey,"In this retrospective study, patch test results of 542 patients (303 female and 239 male), referred to our clinic between June 1996 and July 1999, were evaluated. All patients were patch tested with 32 allergens of an extended European standard series, 140 patients were tested with supplemental series, and 246 patients with their own substances. 280 (51.7%) patients had 1 or more positive results but allergic contact dermatitis, according to clinical relevance, was diagnosed in only 190 (67.9%) of these. Nickel sulfate was the most frequent sensitizer (19.1%), followed by potassium dichromate (11.8%), palladium chloride (9.4%), cobalt chloride (8.5%), and thiuram mix (7.7%). Frequencies of contact allergy to fragrance mix (5.5%), balsam of Peru (Myroxylon Pereirae resin) (2%), quaternium-15 (0.6%), and Kathon CG (methylchloroisothiazolinone+methylisothiazolinone) (0.2%) were relatively low, while no positive reactions were obtained to paraben mix in any case. Current clinical relevance to the present dermatitis was most frequently seen with carba mix (96.2%), thiuram mix (95.2%) and potassium dichromate (78.1%), whereas this rate was low for nickel (37.5%). In 85.8% of patients with allergic contact dermatitis, the responsible allergen was detected by testing with the extended standard series alone (18.4% identified by testing with the additional 10 allergens), in 11.6% by testing with the patients' own substances, and in 2.6% by testing with the supplemental series. Occupational contact dermatitis was diagnosed in 77 of the patients with positive reactions (27.5%), most of these being construction workers and house painters who showed relevant sensitizations to potassium dichromate, cobalt chloride, thiuram mix and carba mix. There was no statistically significant difference in the total contact sensitization rate between atopics and non-atopics, but contact sensitivity to nickel sulfate and palladium chloride was significantly higher among atopics. MOAHL index in % was: 44.1/14.2/24.9/ 54.4/2.4. In conclusion, we believe that similar large series of patients would be helpful to delineate the exact profile of contact dermatitis in Turkey.","Patch test results in 542 patients with suspected contact dermatitis in Turkey Abs: In this retrospective study, patch test results of 542 patients (303 female and 239 male), referred to our clinic between June 1996 and July 1999, were evaluated. All patients were patch tested with 32 allergens of an extended European standard series, 140 patients were tested with supplemental series, and 246 patients with their own substances. 280 (51.7%) patients had 1 or more positive results but allergic contact dermatitis, according to clinical relevance, was diagnosed in only 190 (67.9%) of these. Nickel sulfate was the most frequent sensitizer (19.1%), followed by potassium dichromate (11.8%), palladium chloride (9.4%), cobalt chloride (8.5%), and thiuram mix (7.7%). Frequencies of contact allergy to fragrance mix (5.5%), balsam of Peru (Myroxylon Pereirae resin) (2%), quaternium-15 (0.6%), and Kathon CG (methylchloroisothiazolinone+methylisothiazolinone) (0.2%) were relatively low, while no positive reactions were obtained to paraben mix in any case. Current clinical relevance to the present dermatitis was most frequently seen with carba mix (96.2%), thiuram mix (95.2%) and potassium dichromate (78.1%), whereas this rate was low for nickel (37.5%). In 85.8% of patients with allergic contact dermatitis, the responsible allergen was detected by testing with the extended standard series alone (18.4% identified by testing with the additional 10 allergens), in 11.6% by testing with the patients' own substances, and in 2.6% by testing with the supplemental series. Occupational contact dermatitis was diagnosed in 77 of the patients with positive reactions (27.5%), most of these being construction workers and house painters who showed relevant sensitizations to potassium dichromate, cobalt chloride, thiuram mix and carba mix. There was no statistically significant difference in the total contact sensitization rate between atopics and non-atopics, but contact sensitivity to nickel sulfate and palladium chloride was significantly higher among atopics. MOAHL index in % was: 44.1/14.2/24.9/ 54.4/2.4. In conclusion, we believe that similar large series of patients would be helpful to delineate the exact profile of contact dermatitis in Turkey."
1026817,Das Gupta et al. 2009,Effect of garlic (Allium sativum) on nickel II or chromium VI induced alterations of glucose homeostasis and hepatic antioxidant status under sub-chronic exposure conditions,"Garlic (Allium sativum) has a profound effect in reducing plasma glucose and increasing serum insulin in diabetic rats. We studied the effect of a garlic extract on nickel- or chromium-induced alteration of plasma glucose and hepatic glycogen levels and anti-oxidant status in rats. Adult male albino rats (n=36) divided into six groups of six animals each were treated as follows: Group I, untreated controls; Group II, fresh aqueous homogenate of garlic; Group III, nickel sulfate; Group IV, nickel sulfate + garlic; Group V, potassium dichromate; Group VI, potassium dichromate + garlic. In Groups IV and VI, the simultaneous administration of garlic abrogated a significant nickel- or chromium-induced increase in plasma glucose and decrease in liver glycogen. Nickel and chromium alone also increased lipid peroxide (LPO) and decreased glutathione levels, as well as the activity of superoxide dismutase (SOD), catalase, and glutathione peroxidase. Simultaneous garlic administration significantly reduced the LPO level and remarkably improved SOD activity. Hence, we postulate that the administration of garlic can prevent nickel II- or chromium VI-induced alterations in blood glucose homeostasis while exerting a hepatoprotective effect on glycogen levels and antioxidant status in male albino rats.","Effect of garlic (Allium sativum) on nickel II or chromium VI induced alterations of glucose homeostasis and hepatic antioxidant status under sub-chronic exposure conditions Abs: Garlic (Allium sativum) has a profound effect in reducing plasma glucose and increasing serum insulin in diabetic rats. We studied the effect of a garlic extract on nickel- or chromium-induced alteration of plasma glucose and hepatic glycogen levels and anti-oxidant status in rats. Adult male albino rats (n=36) divided into six groups of six animals each were treated as follows: Group I, untreated controls; Group II, fresh aqueous homogenate of garlic; Group III, nickel sulfate; Group IV, nickel sulfate + garlic; Group V, potassium dichromate; Group VI, potassium dichromate + garlic. In Groups IV and VI, the simultaneous administration of garlic abrogated a significant nickel- or chromium-induced increase in plasma glucose and decrease in liver glycogen. Nickel and chromium alone also increased lipid peroxide (LPO) and decreased glutathione levels, as well as the activity of superoxide dismutase (SOD), catalase, and glutathione peroxidase. Simultaneous garlic administration significantly reduced the LPO level and remarkably improved SOD activity. Hence, we postulate that the administration of garlic can prevent nickel II- or chromium VI-induced alterations in blood glucose homeostasis while exerting a hepatoprotective effect on glycogen levels and antioxidant status in male albino rats."
1026710,Cocker et al. 2007,Biomonitoring at the UK Health and Safety Laboratory,"The UK Health and Safety Laboratory (HSL) provides research and analytical support to the Health and Safety Executive, other Government Departments and employers. In the area of biomonitoring HSL conducts research studies and provides an analytical service for regular surveillance of worker exposure to hazardous substances. This paper gives brief examples of how data from such studies can be used to develop biological monitoring guidance values for isocyanates, polycyclic aromatic hydrocarbons and hexavalent chromium. In addition, a study of occupational exposure to copper chrome arsenic wood preservatives is briefly described to show how biological monitoring can be used for post-approval surveillance of a biocide.","Biomonitoring at the UK Health and Safety Laboratory Abs: The UK Health and Safety Laboratory (HSL) provides research and analytical support to the Health and Safety Executive, other Government Departments and employers. In the area of biomonitoring HSL conducts research studies and provides an analytical service for regular surveillance of worker exposure to hazardous substances. This paper gives brief examples of how data from such studies can be used to develop biological monitoring guidance values for isocyanates, polycyclic aromatic hydrocarbons and hexavalent chromium. In addition, a study of occupational exposure to copper chrome arsenic wood preservatives is briefly described to show how biological monitoring can be used for post-approval surveillance of a biocide."
1026558,Vutukuru et al. 2007,"Effect of arsenic and chromium on the serum amino-transferases activity in Indian major carp, Labeo rohita","Arsenic and hexavalent chromium toxicity results from their ability to interact with sulfahydryl groups of proteins and enzymes, and to substitute phosphorus in a variety of biochemical reactions. Alanine aminotransferase (ALT; E.C: 2.6.1.2) and Aspartate amino transferase (AST; EC 2.6.1.1) play a crucial role in transamination reactions and can be used as potential biomarkers to indicate hepatotoxicity and cellular damage. While histopathological studies in liver tissue require more time and expertise, simple and reliable biochemical analysis of ALT and AST can be used for a rapid assessment of tissue and cellular damage within 96 h. The main objective of this study was to determine the acute effects of arsenic and hexavalent chromium on the activity of ALT and AST in the Indian major carp, Labeo rohita for 24 h and 96 h. Significant increase in the activity of ALT (P &lt; 0.01) from controls in arsenic exposed fish indicates serious hepatic damage and distress condition to the fish. However, no such significant changes were observed in chromium-exposed fish suggesting that arsenic is more toxic to the fish. These findings indicate that ALT and AST are candidate biomarkers for arsenic-induced hepatotoxicity in Labeo rohita.","Effect of arsenic and chromium on the serum amino-transferases activity in Indian major carp, Labeo rohita Abs: Arsenic and hexavalent chromium toxicity results from their ability to interact with sulfahydryl groups of proteins and enzymes, and to substitute phosphorus in a variety of biochemical reactions. Alanine aminotransferase (ALT; E.C: 2.6.1.2) and Aspartate amino transferase (AST; EC 2.6.1.1) play a crucial role in transamination reactions and can be used as potential biomarkers to indicate hepatotoxicity and cellular damage. While histopathological studies in liver tissue require more time and expertise, simple and reliable biochemical analysis of ALT and AST can be used for a rapid assessment of tissue and cellular damage within 96 h. The main objective of this study was to determine the acute effects of arsenic and hexavalent chromium on the activity of ALT and AST in the Indian major carp, Labeo rohita for 24 h and 96 h. Significant increase in the activity of ALT (P &lt; 0.01) from controls in arsenic exposed fish indicates serious hepatic damage and distress condition to the fish. However, no such significant changes were observed in chromium-exposed fish suggesting that arsenic is more toxic to the fish. These findings indicate that ALT and AST are candidate biomarkers for arsenic-induced hepatotoxicity in Labeo rohita."
1026515,Lundholm et al. 2007,"Fate of Cu, Cr, and As during combustion of impregnated wood with and without peat additive","The E.U. Directive on incineration of waste regulates the harmful emissions of particles and twelve toxic elements, including copper, chromium, and arsenic. More information is critically needed on the speciation and behavior of these trace elements during combustion, including the effects of different process variables, as well as of different fuels and fuel mixtures. Using a 15 kW pellets-fueled grate burner, experiments were performed to determine the fate of copper, chromium, and arsenic during combustion of chromate copper arsenate (CCA) preservative wood. The effects of co-combustion of CCA-wood with peat were also studied since peat fuels previously have proved to generally reduce ash related problems. The fate and speciation of copper, chromium, and arsenic were determined from analysis of the flue gas particles and the bottom ash using SEM-EDS, XRD, XPS, and ICP-AES. In addition, chemical equilibrium model calculations were performed to interpret the experimental findings. The results revealed that about 5% copper, 15% chromium, and 60% arsenic were volatilized during combustion of pure CCA-wood, which is lower than predicted volatilization from the individual arsenic, chromium, and copper oxides. This is explained by the formation of more stable refractory complex oxide phases for which the stability trends and patterns are presented. When co-combusted with peat, an additional stabilization of these phases was obtained and thus a small but noteworthy decrease in volatilization of all three elements was observed. The major identified phases for all fuels were CuCrO2(s), (Fe, Mg, Cu)(Cr, Fe, Al)04(s), Cr2O3(s), and Ca3(AsO4)2(s). Arsenic was also identified in the fine particles as KH2AsO4(s) and As2O3(s). A strong indication of hexavalent chromium in the form of K2CrO4 or as a solid solution between K3Na(CrO4)2 and K3Na(SO4)2 was found in the fine particles. Good qualitative agreement was observed between experimental data and chemical equilibrium model calculations.","Fate of Cu, Cr, and As during combustion of impregnated wood with and without peat additive Abs: The E.U. Directive on incineration of waste regulates the harmful emissions of particles and twelve toxic elements, including copper, chromium, and arsenic. More information is critically needed on the speciation and behavior of these trace elements during combustion, including the effects of different process variables, as well as of different fuels and fuel mixtures. Using a 15 kW pellets-fueled grate burner, experiments were performed to determine the fate of copper, chromium, and arsenic during combustion of chromate copper arsenate (CCA) preservative wood. The effects of co-combustion of CCA-wood with peat were also studied since peat fuels previously have proved to generally reduce ash related problems. The fate and speciation of copper, chromium, and arsenic were determined from analysis of the flue gas particles and the bottom ash using SEM-EDS, XRD, XPS, and ICP-AES. In addition, chemical equilibrium model calculations were performed to interpret the experimental findings. The results revealed that about 5% copper, 15% chromium, and 60% arsenic were volatilized during combustion of pure CCA-wood, which is lower than predicted volatilization from the individual arsenic, chromium, and copper oxides. This is explained by the formation of more stable refractory complex oxide phases for which the stability trends and patterns are presented. When co-combusted with peat, an additional stabilization of these phases was obtained and thus a small but noteworthy decrease in volatilization of all three elements was observed. The major identified phases for all fuels were CuCrO2(s), (Fe, Mg, Cu)(Cr, Fe, Al)04(s), Cr2O3(s), and Ca3(AsO4)2(s). Arsenic was also identified in the fine particles as KH2AsO4(s) and As2O3(s). A strong indication of hexavalent chromium in the form of K2CrO4 or as a solid solution between K3Na(CrO4)2 and K3Na(SO4)2 was found in the fine particles. Good qualitative agreement was observed between experimental data and chemical equilibrium model calculations."
1025904,Sau et al. 2008,Isolation and characterization of a Cr(VI) reducing Bacillus firmus strain from industrial effluents,"A chromium resistant bacterial strain KUCr1 exhibiting potential Cr(VI) reducing ability under in vitro aerobic condition is reported. The bacterial strain showed varied degree of resistance to different heavy metals. The MIC of chromium to this strain was found to be 950 mM under aerobic culture condition in complex medium. The factors affecting Cr(VI) reduction by this strain under culture condition were evaluated. Maximal Cr(VI) reduction was observed at the pH 8 to 10 and at a temperature of 35 degrees C. Higher concentration of Cr(VI) slowed down the reduction, eventually all the metal could be reduced with longer incubation time. Different toxic metals showed differential effect on reduction. Cadmium and zinc were found to inhibit reduction. Cr(VI) reduction and bioremediation were found to be related to the growth supportive condition in terms of carbon, phosphorous and nitrogen supply in wastewater fed with tannery effluent indicating cell mass dependency of Cr(VI) reduction. Through biochemical characterization and 16S rDNA sequence analysis, the strain KUCr1, as the name given to it, was identified as a strain of Bacillus firmus.","Isolation and characterization of a Cr(VI) reducing Bacillus firmus strain from industrial effluents Abs: A chromium resistant bacterial strain KUCr1 exhibiting potential Cr(VI) reducing ability under in vitro aerobic condition is reported. The bacterial strain showed varied degree of resistance to different heavy metals. The MIC of chromium to this strain was found to be 950 mM under aerobic culture condition in complex medium. The factors affecting Cr(VI) reduction by this strain under culture condition were evaluated. Maximal Cr(VI) reduction was observed at the pH 8 to 10 and at a temperature of 35 degrees C. Higher concentration of Cr(VI) slowed down the reduction, eventually all the metal could be reduced with longer incubation time. Different toxic metals showed differential effect on reduction. Cadmium and zinc were found to inhibit reduction. Cr(VI) reduction and bioremediation were found to be related to the growth supportive condition in terms of carbon, phosphorous and nitrogen supply in wastewater fed with tannery effluent indicating cell mass dependency of Cr(VI) reduction. Through biochemical characterization and 16S rDNA sequence analysis, the strain KUCr1, as the name given to it, was identified as a strain of Bacillus firmus."
1025749,Rudolf and  Cervinka 2010,Nickel modifies the cytotoxicity of hexavalent chromium in human dermal fibroblasts,"We investigated combined effects of hexavalent chromium and nickel on viability, intracellular signaling and cell death of primary human skin fibroblasts during 24 h of exposure. We show that nickel at non-toxic concentrations prevents hexavalent chromium-induced cell damage and apoptosis, mainly by overexpression of heat shock proteins (HSPs), in particular HSP27 and activation of nuclear factor kappa B (NFkappaB) as demonstrated by specific knockdown of HSPs or NFkappaB. Conversely, cytotoxic nickel concentrations which induce apoptosis in dermal fibroblasts by themselves act to enhance hexavalent chromium effects in the same cells by stimulating oxidative stress and depleting ATP leading to rapid necrosis as demonstrated by markedly increased LDH release in exposed cells. Using specific pharmacological inhibitors it was further demonstrated that oxidative stress and PARP-1 activity are responsible for rapid necrosis. In conclusion, exposure of dermal fibroblasts to high nickel concentrations in combination with hexavalent chromium may result in rapid cell damage leading to necrosis while low nickel concentrations may prevent hexavalent chromium-induced cell death with potential accumulation of damaged but otherwise viable cells.","Nickel modifies the cytotoxicity of hexavalent chromium in human dermal fibroblasts Abs: We investigated combined effects of hexavalent chromium and nickel on viability, intracellular signaling and cell death of primary human skin fibroblasts during 24 h of exposure. We show that nickel at non-toxic concentrations prevents hexavalent chromium-induced cell damage and apoptosis, mainly by overexpression of heat shock proteins (HSPs), in particular HSP27 and activation of nuclear factor kappa B (NFkappaB) as demonstrated by specific knockdown of HSPs or NFkappaB. Conversely, cytotoxic nickel concentrations which induce apoptosis in dermal fibroblasts by themselves act to enhance hexavalent chromium effects in the same cells by stimulating oxidative stress and depleting ATP leading to rapid necrosis as demonstrated by markedly increased LDH release in exposed cells. Using specific pharmacological inhibitors it was further demonstrated that oxidative stress and PARP-1 activity are responsible for rapid necrosis. In conclusion, exposure of dermal fibroblasts to high nickel concentrations in combination with hexavalent chromium may result in rapid cell damage leading to necrosis while low nickel concentrations may prevent hexavalent chromium-induced cell death with potential accumulation of damaged but otherwise viable cells."
1025744,Helsing et al. 2010,Variability in patch test reactions--first report from the Norwegian Patch Test Registry,"<strong>BACKGROUND: </strong>A nation-wide Norwegian Patch Test Registry (NOLAR) was established in 2005 as a collaboration between six dermatology departments. International, multi-centre studies have documented great variability in the frequency of positive patch test reactions, considered as mainly due to heterogeneity of test populations.<br /><br /><strong>OBJECTIVES: </strong>To analyse the variability of positive test reactions by studying patch tests performed at the six collaborating departments, using standardized procedures.<br /><br /><strong>MATERIALS AND METHODS: </strong>Data from all patch tests (n = 2089) performed in 2007-2008 as registered in the NOLAR program. Differences between centres were analysed using Exact Pearson chi(2) test.<br /><br /><strong>RESULTS: </strong>Between the centres, positive test reactions (+, ++, or +++) varied significantly for 8 of the 26 allergens in the European Baseline Series. When considering strong reactions (++ or +++) only, the differences were statistically significant for six of these allergens, i.e. cobalt chloride, potassium dichromate, p-phenylenediamine, formaldehyde, paraben mix, and mercaptobenzothiazole.<br /><br /><strong>CONCLUSION: </strong>The results indicate regional differences in the prevalence of sensitization to certain allergens within the Norwegian population, although inter-observer differences cannot be ruled out as a factor.","Variability in patch test reactions--first report from the Norwegian Patch Test Registry Abs: <strong>BACKGROUND: </strong>A nation-wide Norwegian Patch Test Registry (NOLAR) was established in 2005 as a collaboration between six dermatology departments. International, multi-centre studies have documented great variability in the frequency of positive patch test reactions, considered as mainly due to heterogeneity of test populations.<br /><br /><strong>OBJECTIVES: </strong>To analyse the variability of positive test reactions by studying patch tests performed at the six collaborating departments, using standardized procedures.<br /><br /><strong>MATERIALS AND METHODS: </strong>Data from all patch tests (n = 2089) performed in 2007-2008 as registered in the NOLAR program. Differences between centres were analysed using Exact Pearson chi(2) test.<br /><br /><strong>RESULTS: </strong>Between the centres, positive test reactions (+, ++, or +++) varied significantly for 8 of the 26 allergens in the European Baseline Series. When considering strong reactions (++ or +++) only, the differences were statistically significant for six of these allergens, i.e. cobalt chloride, potassium dichromate, p-phenylenediamine, formaldehyde, paraben mix, and mercaptobenzothiazole.<br /><br /><strong>CONCLUSION: </strong>The results indicate regional differences in the prevalence of sensitization to certain allergens within the Norwegian population, although inter-observer differences cannot be ruled out as a factor."
1025737,Thyssen et al. 2010,Patch test reactivity to metal allergens following regulatory interventions: a 33-year retrospective study,"<strong>BACKGROUND: </strong>Contact allergy epidemics to chromate and nickel were addressed in Denmark in 1983 and 1990 by regulatory interventions.<br /><br /><strong>OBJECTIVES: </strong>To evaluate whether regulatory interventions on nickel and chromate exposure have reduced the proportion of strong patch test reactions.<br /><br /><strong>METHODS: </strong>22 506 patients with dermatitis aged 4-99 years were patch tested with nickel sulfate, potassium dichromate, or cobalt chloride between 1977 and 2009.<br /><br /><strong>RESULTS: </strong>The proportion of 3+ reactions to nickel sulfate was reduced and almost disappeared after the mid- and late 1980s (P-trend = 0.001). Today, 1+ and 2+ nickel reactions occur equally frequent. Cobalt chloride patch test reactivity reflected the nickel development to some degree. The proportion of 3+ reactions to potassium dichromate was reduced during the 1980s (P-trend = 0.13), whereas the proportion of 2+ reactions to potassium dichromate have increased in recent years.<br /><br /><strong>CONCLUSIONS: </strong>The decrease in nickel sulfate and cobalt chloride 3+ patch test reactivity began long before the Danish nickel regulation came into effect. This could be because of research activity at the time as well as political attention in Northern Europe. The chromate content in cement regulation may have changed the epidemiology of patch test reactivity; however, in recent years, 2+ reactions to chromate have increased markedly, a development that should be carefully followed.","Patch test reactivity to metal allergens following regulatory interventions: a 33-year retrospective study Abs: <strong>BACKGROUND: </strong>Contact allergy epidemics to chromate and nickel were addressed in Denmark in 1983 and 1990 by regulatory interventions.<br /><br /><strong>OBJECTIVES: </strong>To evaluate whether regulatory interventions on nickel and chromate exposure have reduced the proportion of strong patch test reactions.<br /><br /><strong>METHODS: </strong>22 506 patients with dermatitis aged 4-99 years were patch tested with nickel sulfate, potassium dichromate, or cobalt chloride between 1977 and 2009.<br /><br /><strong>RESULTS: </strong>The proportion of 3+ reactions to nickel sulfate was reduced and almost disappeared after the mid- and late 1980s (P-trend = 0.001). Today, 1+ and 2+ nickel reactions occur equally frequent. Cobalt chloride patch test reactivity reflected the nickel development to some degree. The proportion of 3+ reactions to potassium dichromate was reduced during the 1980s (P-trend = 0.13), whereas the proportion of 2+ reactions to potassium dichromate have increased in recent years.<br /><br /><strong>CONCLUSIONS: </strong>The decrease in nickel sulfate and cobalt chloride 3+ patch test reactivity began long before the Danish nickel regulation came into effect. This could be because of research activity at the time as well as political attention in Northern Europe. The chromate content in cement regulation may have changed the epidemiology of patch test reactivity; however, in recent years, 2+ reactions to chromate have increased markedly, a development that should be carefully followed."
1025695,Magen et al. 2011,Impact of contact sensitization in chronic spontaneous urticaria,"<strong>INTRODUCTION: </strong>Patch testing is performed to diagnose allergic contact dermatitis to avoid exposure to the revealed contact allergens. Nevertheless, patch testing is not routinely performed in the evaluation of patients with chronic idiopathic (spontaneous) urticaria (CIU). The objective of this study was to determine the frequency of sensitization to patch test allergens in severe CIU and assess a role of the allergen avoidance in CIU remission.<br /><br /><strong>METHODS: </strong>The cases of patients with severe CIU were retrospectively studied. The patients were patch tested using T.R.U.E. TEST. Three groups were studied: CIU with positive patch test group; CIU with negative patch test group and control group, which included the cases of not patch-tested patients with CIU. The groups were followed up monthly to assess changes in Chronic Urticaria Severity Score (CUSS) after allergen avoidance.<br /><br /><strong>RESULTS: </strong>Forty-three subjects with severe CIU were patch tested. Nickel sulphate was positive in 4 (9.3%) cases, potassium dichromate in 2 (4.7%) cases, cobalt, balsam of Peru, paraphenylene diamine, fragrance mix and epoxy resin were positive in 1 (2.3%) case. Their baseline CUSS (5.4 ± 0.5) improved significantly after 1 month of allergen avoidance (3.2 ± 1.1; P &lt; 0.001); but similar improvement of CUSS (5.3 ± 0.5) was seen in 34 patients with CIU with negative patch test (3.2 ± 1.3; P &lt; 0.001) and in 49 patients with CIU of control group (5.2 ± 0.4 to 3.4 ± 1.3; P &lt; 0 &lt; 0.001) after 1 month.<br /><br /><strong>CONCLUSIONS: </strong>There is no relationship between avoidance of contact allergens and the course of CIU.","Impact of contact sensitization in chronic spontaneous urticaria Abs: <strong>INTRODUCTION: </strong>Patch testing is performed to diagnose allergic contact dermatitis to avoid exposure to the revealed contact allergens. Nevertheless, patch testing is not routinely performed in the evaluation of patients with chronic idiopathic (spontaneous) urticaria (CIU). The objective of this study was to determine the frequency of sensitization to patch test allergens in severe CIU and assess a role of the allergen avoidance in CIU remission.<br /><br /><strong>METHODS: </strong>The cases of patients with severe CIU were retrospectively studied. The patients were patch tested using T.R.U.E. TEST. Three groups were studied: CIU with positive patch test group; CIU with negative patch test group and control group, which included the cases of not patch-tested patients with CIU. The groups were followed up monthly to assess changes in Chronic Urticaria Severity Score (CUSS) after allergen avoidance.<br /><br /><strong>RESULTS: </strong>Forty-three subjects with severe CIU were patch tested. Nickel sulphate was positive in 4 (9.3%) cases, potassium dichromate in 2 (4.7%) cases, cobalt, balsam of Peru, paraphenylene diamine, fragrance mix and epoxy resin were positive in 1 (2.3%) case. Their baseline CUSS (5.4 ± 0.5) improved significantly after 1 month of allergen avoidance (3.2 ± 1.1; P &lt; 0.001); but similar improvement of CUSS (5.3 ± 0.5) was seen in 34 patients with CIU with negative patch test (3.2 ± 1.3; P &lt; 0.001) and in 49 patients with CIU of control group (5.2 ± 0.4 to 3.4 ± 1.3; P &lt; 0 &lt; 0.001) after 1 month.<br /><br /><strong>CONCLUSIONS: </strong>There is no relationship between avoidance of contact allergens and the course of CIU."
1025692,Modjtahedi et al. 2011,Guinea pig sensitization assays: an experimental comparison of three methods,"<strong>PURPOSE: </strong>Guinea pig sensitization assays provide a critical tool in toxicological testing. Here, we investigate the relative sensitivities of the Guinea Pig Maximization Test (GPMT), the Open Epicutaneous Test (OET), and the Buehler test on seven common compounds.<br /><br /><strong>METHODS: </strong>Seven compounds (formalin, nickel sulfate, 2-benzothiazolethiol, neomycin sulfate, potassium dichromate, ethylenediamine, dihydrochloride, and cinnamyl alcohol) were investigated on 15 guinea pigs per assay. Differences between each assay were investigated individually for each compound in question, and cumulative comparisons were also performed.<br /><br /><strong>RESULTS: </strong>Cumulatively, differences in rates of sensitization between the GPMT and OET did not reach statistical significance; however, both tests produced higher sensitization rates than the Buehler test (1% significance level). Comparisons for individual compounds are outlined within the main text.<br /><br /><strong>CONCLUSIONS: </strong>Our results indicate a possible role for the OET in the testing of weakly allergenic compounds. Similarly, the Buehler test may hold greatest utility in the examination of strongly allergenic compounds, where high sensitivity is not necessary and limited exposure to subjects is desired. These findings may help guide experimental protocols and considerations.","Guinea pig sensitization assays: an experimental comparison of three methods Abs: <strong>PURPOSE: </strong>Guinea pig sensitization assays provide a critical tool in toxicological testing. Here, we investigate the relative sensitivities of the Guinea Pig Maximization Test (GPMT), the Open Epicutaneous Test (OET), and the Buehler test on seven common compounds.<br /><br /><strong>METHODS: </strong>Seven compounds (formalin, nickel sulfate, 2-benzothiazolethiol, neomycin sulfate, potassium dichromate, ethylenediamine, dihydrochloride, and cinnamyl alcohol) were investigated on 15 guinea pigs per assay. Differences between each assay were investigated individually for each compound in question, and cumulative comparisons were also performed.<br /><br /><strong>RESULTS: </strong>Cumulatively, differences in rates of sensitization between the GPMT and OET did not reach statistical significance; however, both tests produced higher sensitization rates than the Buehler test (1% significance level). Comparisons for individual compounds are outlined within the main text.<br /><br /><strong>CONCLUSIONS: </strong>Our results indicate a possible role for the OET in the testing of weakly allergenic compounds. Similarly, the Buehler test may hold greatest utility in the examination of strongly allergenic compounds, where high sensitivity is not necessary and limited exposure to subjects is desired. These findings may help guide experimental protocols and considerations."
1025687,Yin et al. 2011,"A retrospective study of patch tests in Chongqing, China from 2004 to 2009","<strong>BACKGROUND: </strong>There has been no previous report on allergens responsible for dermatitis in southwest China.<br /><br /><strong>OBJECTIVE: </strong>To investigate the prevalence of contact allergy in southwest China, we retrospectively analysed the patch testing results in our department from 2004 to 2009.<br /><br /><strong>METHODS: </strong>A total of 2758 patients were patch tested with the Chinese baseline series of contact allergens (Beijing Medical University), the most common baseline series used in China. The results from patch tests were collected, analysed, and compared with clinical findings.<br /><br /><strong>RESULTS: </strong>Of 2758 patients tested, 1826 (66.2%) were allergic to one or more common allergens. Five hundred (27.4%) patients had more than two contact allergies. One patient showed positive reactions to seven allergens. The most common allergens among the 1826 patients with positive reactions were nickel sulfate (39.5%), potassium dichromate (13.5%), thiomersal (11.6%), fragrance mix (6.9%), and rubber mix IV (5.8%). Nickel sensitivity was more common in female patients, and potassium dichromate sensitivity was more common in male patients (p &lt; 0.001).<br /><br /><strong>CONCLUSION: </strong>Contact allergy in southwest China has particular characteristics, and these findings should be helpful in the development of strategies to reduce contact allergy in this geographical region.","A retrospective study of patch tests in Chongqing, China from 2004 to 2009 Abs: <strong>BACKGROUND: </strong>There has been no previous report on allergens responsible for dermatitis in southwest China.<br /><br /><strong>OBJECTIVE: </strong>To investigate the prevalence of contact allergy in southwest China, we retrospectively analysed the patch testing results in our department from 2004 to 2009.<br /><br /><strong>METHODS: </strong>A total of 2758 patients were patch tested with the Chinese baseline series of contact allergens (Beijing Medical University), the most common baseline series used in China. The results from patch tests were collected, analysed, and compared with clinical findings.<br /><br /><strong>RESULTS: </strong>Of 2758 patients tested, 1826 (66.2%) were allergic to one or more common allergens. Five hundred (27.4%) patients had more than two contact allergies. One patient showed positive reactions to seven allergens. The most common allergens among the 1826 patients with positive reactions were nickel sulfate (39.5%), potassium dichromate (13.5%), thiomersal (11.6%), fragrance mix (6.9%), and rubber mix IV (5.8%). Nickel sensitivity was more common in female patients, and potassium dichromate sensitivity was more common in male patients (p &lt; 0.001).<br /><br /><strong>CONCLUSION: </strong>Contact allergy in southwest China has particular characteristics, and these findings should be helpful in the development of strategies to reduce contact allergy in this geographical region."
1025330,Jambeck et al. 2007,CCA-treated wood disposed in landfills and life-cycle trade-offs with waste-to-energy and MSW landfill disposal,"Chromated copper arsenate (CCA)-treated wood is a preservative treated wood construction product that grew in use in the 1970s for both residential and industrial applications. Although some countries have banned the use of the product for some applications, others have not, and the product continues to enter the waste stream from construction, demolition and remodeling projects. CCA-treated wood as a solid waste is managed in various ways throughout the world. In the US, CCA-treated wood is disposed primarily within landfills; however some of the wood is combusted in waste-to-energy (WTE) facilities. In other countries, the predominant disposal option for wood, sometimes including CCA-treated wood, is combustion for the production of energy. This paper presents an estimate of the quantity of CCA-treated wood entering the disposal stream in the US, as well as an examination of the trade-offs between landfilling and WTE combustion of CCA-treated wood through a life-cycle assessment and decision support tool (MSW DST). Based upon production statistics, the estimated life span and the phaseout of CCA-treated wood, recent disposal projections estimate the peak US disposal rate to occur in 2008, at 9.7 million m(3). CCA-treated wood, when disposed with construction and demolition (C&amp;D) debris and municipal solid waste (MSW), has been found to increase arsenic and chromium concentrations in leachate. For this reason, and because MSW landfills are lined, MSW landfills have been recommended as a preferred disposal option over unlined C&amp;D debris landfills. Between landfilling and WTE for the same mass of CCA-treated wood, WTE is more expensive (nearly twice the cost), but when operated in accordance with US Environmental Protection Agency (US EPA) regulations, it produces energy and does not emit fossil carbon emissions. If the wood is managed via WTE, less landfill area is required, which could be an influential trade-off in some countries. Although metals are concentrated in the ash in the WTE scenario, the MSW landfill scenario releases a greater amount of arsenic from leachate in a more dilute form. The WTE scenario releases more chromium from the ash on an annual basis. The WTE facility and subsequent ash disposal greatly concentrates the chromium, often oxidizing it to the more toxic and mobile Cr(VI) form. Elevated arsenic and chromium concentrations in the ash leachate may increase leachate management costs.","CCA-treated wood disposed in landfills and life-cycle trade-offs with waste-to-energy and MSW landfill disposal Abs: Chromated copper arsenate (CCA)-treated wood is a preservative treated wood construction product that grew in use in the 1970s for both residential and industrial applications. Although some countries have banned the use of the product for some applications, others have not, and the product continues to enter the waste stream from construction, demolition and remodeling projects. CCA-treated wood as a solid waste is managed in various ways throughout the world. In the US, CCA-treated wood is disposed primarily within landfills; however some of the wood is combusted in waste-to-energy (WTE) facilities. In other countries, the predominant disposal option for wood, sometimes including CCA-treated wood, is combustion for the production of energy. This paper presents an estimate of the quantity of CCA-treated wood entering the disposal stream in the US, as well as an examination of the trade-offs between landfilling and WTE combustion of CCA-treated wood through a life-cycle assessment and decision support tool (MSW DST). Based upon production statistics, the estimated life span and the phaseout of CCA-treated wood, recent disposal projections estimate the peak US disposal rate to occur in 2008, at 9.7 million m(3). CCA-treated wood, when disposed with construction and demolition (C&amp;D) debris and municipal solid waste (MSW), has been found to increase arsenic and chromium concentrations in leachate. For this reason, and because MSW landfills are lined, MSW landfills have been recommended as a preferred disposal option over unlined C&amp;D debris landfills. Between landfilling and WTE for the same mass of CCA-treated wood, WTE is more expensive (nearly twice the cost), but when operated in accordance with US Environmental Protection Agency (US EPA) regulations, it produces energy and does not emit fossil carbon emissions. If the wood is managed via WTE, less landfill area is required, which could be an influential trade-off in some countries. Although metals are concentrated in the ash in the WTE scenario, the MSW landfill scenario releases a greater amount of arsenic from leachate in a more dilute form. The WTE scenario releases more chromium from the ash on an annual basis. The WTE facility and subsequent ash disposal greatly concentrates the chromium, often oxidizing it to the more toxic and mobile Cr(VI) form. Elevated arsenic and chromium concentrations in the ash leachate may increase leachate management costs."
1025247,Martin et al. 2008,Removal of nuisance aqueous anions with Ferrilig,"The present study describes an improved synthesis of Ferrilig, an iron(III) salt of a commercially available immobilized ligand, IMLIG, called Octolig. The resulting composite, called &quot;Ferrilig&quot; was used to remove arsenate, chromate, molybdate, and selenite ions from aqueous solutions by means of column chromatography. The synthesis of Ferrilig was accomplished by treating an aqueous suspension of Octolig-21 with an equal weight of ferrous sulfate heptahydrate under nitrogen. The ferrous salt was then collected by sieving and allowed to oxidize to the iron (III) salt by exposure to air; treatment with dilute sodium hydroxide converted the composite to the hydroxide. Using 300 ppb As (as Na(2)HAsO(4).7H(2)O) and column chromatography, the arsenic concentration in the effluent was less than the detection limit (&lt; 2 ppb). Chromium as sodium chromate, molybdenum as (NH(4))(6) Mo(7)O(24).4H(2)O, and selenium as Na(2)Se0(3), were removed with fair success. The elements, their initial concentrations and their percentage removal (parenthetically) were: As (280 ppb, 99%), Cr (50.6 ppm, 95.5%), Mo (50.7 ppm, 94.6%), Se (258 ppm, 99.9%).","Removal of nuisance aqueous anions with Ferrilig Abs: The present study describes an improved synthesis of Ferrilig, an iron(III) salt of a commercially available immobilized ligand, IMLIG, called Octolig. The resulting composite, called &quot;Ferrilig&quot; was used to remove arsenate, chromate, molybdate, and selenite ions from aqueous solutions by means of column chromatography. The synthesis of Ferrilig was accomplished by treating an aqueous suspension of Octolig-21 with an equal weight of ferrous sulfate heptahydrate under nitrogen. The ferrous salt was then collected by sieving and allowed to oxidize to the iron (III) salt by exposure to air; treatment with dilute sodium hydroxide converted the composite to the hydroxide. Using 300 ppb As (as Na(2)HAsO(4).7H(2)O) and column chromatography, the arsenic concentration in the effluent was less than the detection limit (&lt; 2 ppb). Chromium as sodium chromate, molybdenum as (NH(4))(6) Mo(7)O(24).4H(2)O, and selenium as Na(2)Se0(3), were removed with fair success. The elements, their initial concentrations and their percentage removal (parenthetically) were: As (280 ppb, 99%), Cr (50.6 ppm, 95.5%), Mo (50.7 ppm, 94.6%), Se (258 ppm, 99.9%)."
1025128,Haubenstricker et al. 1990,Rapid toxicity testing based on mitochondrial respiratory activity,,Rapid toxicity testing based on mitochondrial respiratory activity Abs: 
1025102,Rank and  Nielsen 1994,Evaluation of the Allium anaphase-telophase test in relation to genotoxicity screening of industrial wastewater,"The Allium anaphase-telophase test was evaluated to find out if it could be recommended in the screening of wastewater for genotoxicity. Five mutagenic or carcinogenic chemicals usually found in wastewater were tested in the Allium anaphase-telophase test. Sodium dichromate (25 microM), benzene (100 microM), dichloromethane (175 microM) and 1,1,1-trichloromethane (175 microM) increased the frequency of chromosome aberrations in the root cells, whereas formaldehyde (1 mM) was found to be non-mutagenic in this test system. Other studies where chemicals were tested in the Allium test were reviewed. For 15 chemicals the results were compared with results from the Ames test, the Microscreen assay, and carcinogenicity tests in rodents. The sensitivity of the Allium test was calculated to be 82%. In conclusion the Allium test is recommended for the screening of wastewater because it has a high sensitivity, is cheap, rapid, easy to handle, and because it can be used on wastewater without pretreatment of the sample.","Evaluation of the Allium anaphase-telophase test in relation to genotoxicity screening of industrial wastewater Abs: The Allium anaphase-telophase test was evaluated to find out if it could be recommended in the screening of wastewater for genotoxicity. Five mutagenic or carcinogenic chemicals usually found in wastewater were tested in the Allium anaphase-telophase test. Sodium dichromate (25 microM), benzene (100 microM), dichloromethane (175 microM) and 1,1,1-trichloromethane (175 microM) increased the frequency of chromosome aberrations in the root cells, whereas formaldehyde (1 mM) was found to be non-mutagenic in this test system. Other studies where chemicals were tested in the Allium test were reviewed. For 15 chemicals the results were compared with results from the Ames test, the Microscreen assay, and carcinogenicity tests in rodents. The sensitivity of the Allium test was calculated to be 82%. In conclusion the Allium test is recommended for the screening of wastewater because it has a high sensitivity, is cheap, rapid, easy to handle, and because it can be used on wastewater without pretreatment of the sample."
1025064,Haubenstricker et al. 1990,Rapid toxicity testing based on yeast respiratory activity,,Rapid toxicity testing based on yeast respiratory activity Abs: 
1023818,Kazi and  Cooper 2006,Method to recover and reuse chromated copper arsenate wood preservative from spent treated wood,"The volume of chromated copper arsenate (CCA) treated wood products coming out of service is expected to increase dramatically during the next decade. There is a need for an alternative waste management approach to landfilling. This paper investigates the variables affecting extraction of CCA components from wood particles and the potential to oxidize and reuse the recovered chemicals. Most of the CCA components could be extracted by 10% H2O2 at 50 degrees C in 6 h with an average extraction efficiency of 95% for Cr, 94% for Cu and 98% for As. The extract containing Cr(III), Cu(II) and As(V) could be oxidized in several stages by aqueous 2.5% w/w H2O2 in less than 2 h to a condition where it was compatible with CCA treating solutions and could be reused for treating new wood. When the recovered extract was mixed with fresh CCA solution in different ratios, the mixed CCA-C solutions had similar solution stability as freshly prepared CCA-C solution and treated wood had similar leaching properties as wood treated with fresh solution.","Method to recover and reuse chromated copper arsenate wood preservative from spent treated wood Abs: The volume of chromated copper arsenate (CCA) treated wood products coming out of service is expected to increase dramatically during the next decade. There is a need for an alternative waste management approach to landfilling. This paper investigates the variables affecting extraction of CCA components from wood particles and the potential to oxidize and reuse the recovered chemicals. Most of the CCA components could be extracted by 10% H2O2 at 50 degrees C in 6 h with an average extraction efficiency of 95% for Cr, 94% for Cu and 98% for As. The extract containing Cr(III), Cu(II) and As(V) could be oxidized in several stages by aqueous 2.5% w/w H2O2 in less than 2 h to a condition where it was compatible with CCA treating solutions and could be reused for treating new wood. When the recovered extract was mixed with fresh CCA solution in different ratios, the mixed CCA-C solutions had similar solution stability as freshly prepared CCA-C solution and treated wood had similar leaching properties as wood treated with fresh solution."
1023550,Toal et al. 2005,Luminescent silole nanoparticles as chemoselective sensors for Cr(VI),"Colloidal suspensions of 3-aminopropylmethyl(tetraphenyl)silole nanoparticles can be used as selective chemosensors for carcinogenic chromium(VI) analyte. Methylhydrosilole is functionalized by hydrosilation of allylamine, and the colloid is prepared by the rapid addition of water to a THF solution of the silole. The method of detection is through electron-transfer quenching of the fluorescence of the silole colloid (lambda(em) = 485 nm at 360 nm excitation) by the analytes, with hundred parts per billion detection limits. Stern-Volmer plots are linear up to 10 ppm in the case of chromium, but exhibit saturation behavior near 5-10 ppm for arsenic. Dynamic light scattering experiments and AFM measurements show the particle sizes to be around 100 nm in diameter and dependent on solvent composition, with a particle size dispersity of +/-25%. The fluorescence lifetimes of the silole in solution and colloid are approximately 31 ps and approximately 4.3 ns, respectively, while the silole has a lifetime of 6 ns in the bulk solid. A minimum volume fraction of 80% water is necessary to precipitate the colloid from THF, and the luminescence continues to rise with higher water fractions. Colloids in a pH 7 phosphate-buffered suspension show both higher sensitivity and greater selectivity (100-fold) for CrO4(2-) detection than for other oxoanion interferents, NO3-, NO2-, SO4(2-), and ClO4-.","Luminescent silole nanoparticles as chemoselective sensors for Cr(VI) Abs: Colloidal suspensions of 3-aminopropylmethyl(tetraphenyl)silole nanoparticles can be used as selective chemosensors for carcinogenic chromium(VI) analyte. Methylhydrosilole is functionalized by hydrosilation of allylamine, and the colloid is prepared by the rapid addition of water to a THF solution of the silole. The method of detection is through electron-transfer quenching of the fluorescence of the silole colloid (lambda(em) = 485 nm at 360 nm excitation) by the analytes, with hundred parts per billion detection limits. Stern-Volmer plots are linear up to 10 ppm in the case of chromium, but exhibit saturation behavior near 5-10 ppm for arsenic. Dynamic light scattering experiments and AFM measurements show the particle sizes to be around 100 nm in diameter and dependent on solvent composition, with a particle size dispersity of +/-25%. The fluorescence lifetimes of the silole in solution and colloid are approximately 31 ps and approximately 4.3 ns, respectively, while the silole has a lifetime of 6 ns in the bulk solid. A minimum volume fraction of 80% water is necessary to precipitate the colloid from THF, and the luminescence continues to rise with higher water fractions. Colloids in a pH 7 phosphate-buffered suspension show both higher sensitivity and greater selectivity (100-fold) for CrO4(2-) detection than for other oxoanion interferents, NO3-, NO2-, SO4(2-), and ClO4-."
1023518,Fulladosa et al. 2005,"Effect of cadmium(II), chromium(VI), and arsenic(V) on long-term viability- and growth-inhibition assays using Vibrio fischeri marine bacteria","As a complement to previous results obtained using the standard Microtox acute-toxicity test, which is based on measuring the rapid decrease of bioluminescence (5 to 30 minutes of exposure) in Vibrio fischeri bacteria in the presence of toxicants, the long-term effects of Cd(II), Cr(VI), and As(V) were studied on growth rate and viability assays of the same bacteria adapted to longer-lasting cultures, i.e., 48 or 72 hours instead of 5 or 30 minutes. Effects on viability or growth, as studied by establishing dose- and time-response curves, confirmed that these poisonous chemicals were not particularly toxic to these bacteria. Nevertheless, in the case of Cr(VI), the viability-inhibition assay appeared to be more sensitive than the Microtox acute-toxicity test. Interestingly, it was possible to observe a clear hormesis phenomenon, especially for Cd(II), under the conditions of both viability- and growth-inhibition assays.","Effect of cadmium(II), chromium(VI), and arsenic(V) on long-term viability- and growth-inhibition assays using Vibrio fischeri marine bacteria Abs: As a complement to previous results obtained using the standard Microtox acute-toxicity test, which is based on measuring the rapid decrease of bioluminescence (5 to 30 minutes of exposure) in Vibrio fischeri bacteria in the presence of toxicants, the long-term effects of Cd(II), Cr(VI), and As(V) were studied on growth rate and viability assays of the same bacteria adapted to longer-lasting cultures, i.e., 48 or 72 hours instead of 5 or 30 minutes. Effects on viability or growth, as studied by establishing dose- and time-response curves, confirmed that these poisonous chemicals were not particularly toxic to these bacteria. Nevertheless, in the case of Cr(VI), the viability-inhibition assay appeared to be more sensitive than the Microtox acute-toxicity test. Interestingly, it was possible to observe a clear hormesis phenomenon, especially for Cd(II), under the conditions of both viability- and growth-inhibition assays."
1023501,Su et al. 2005,Phytotoxicity and phytoaccumulation of trivalent and hexavalent chromium in brake fern,"A recently recognized hyperaccumulator plant, Chinese brake fern (Pteris vittata), has been found to extract very high concentration of arsenic from arsenic-contaminated soil. Chromium usually is a coexisting contaminant with arsenic in most contaminated soils. The potential application of ferns for phytoremediation of chromium(III)- and chromium(VI)-contaminated soils and their phytotoxicity to ferns has not been studied before. In this study, chromium distribution and phytotoxicity at the plant and cellular levels of brake ferns were studied using chemical analyses and scanning electron microscopy. The results show a higher phytotoxicity of Cr from Cr(VI)-contaminated soil to Chinese brake fern than from Cr(III)-contaminated soil. Phytotoxicity symptoms included significant decreases both in fresh biomass weight and relative water content (RWC), and also in leaf chlorosis during the late stage of growing. At higher concentrations (500 mg/kg Cr[VI] and 1,000 mg/kg Cr[III] addition), plants showed reduction in the number of palisade and spongy parenchyma cells in leaves. Compared with other plant species reported for phytoremediation of Cr(VI)-contaminated soil, brake fern took up and accumulated significant amounts of Cr (up to 1,145 mg/kg in shoots and 5,717 mg/kg in roots) and did not die immediately from phytotoxicity. Our study suggests that Chinese brake fern is a potential candidate for phytoremediation of Cr(VI)-contaminated soils, even though plants showed severe phytotoxic symptoms at higher soil Cr concentrations.","Phytotoxicity and phytoaccumulation of trivalent and hexavalent chromium in brake fern Abs: A recently recognized hyperaccumulator plant, Chinese brake fern (Pteris vittata), has been found to extract very high concentration of arsenic from arsenic-contaminated soil. Chromium usually is a coexisting contaminant with arsenic in most contaminated soils. The potential application of ferns for phytoremediation of chromium(III)- and chromium(VI)-contaminated soils and their phytotoxicity to ferns has not been studied before. In this study, chromium distribution and phytotoxicity at the plant and cellular levels of brake ferns were studied using chemical analyses and scanning electron microscopy. The results show a higher phytotoxicity of Cr from Cr(VI)-contaminated soil to Chinese brake fern than from Cr(III)-contaminated soil. Phytotoxicity symptoms included significant decreases both in fresh biomass weight and relative water content (RWC), and also in leaf chlorosis during the late stage of growing. At higher concentrations (500 mg/kg Cr[VI] and 1,000 mg/kg Cr[III] addition), plants showed reduction in the number of palisade and spongy parenchyma cells in leaves. Compared with other plant species reported for phytoremediation of Cr(VI)-contaminated soil, brake fern took up and accumulated significant amounts of Cr (up to 1,145 mg/kg in shoots and 5,717 mg/kg in roots) and did not die immediately from phytotoxicity. Our study suggests that Chinese brake fern is a potential candidate for phytoremediation of Cr(VI)-contaminated soils, even though plants showed severe phytotoxic symptoms at higher soil Cr concentrations."
1023091,Kuehn and  Pattard 1990,Results of the harmful effects of water pollutants to green algae (Scenedesmus subspicatus) in the cell multiplication inhibition test,"BIOSIS COPYRIGHT: BIOL ABS. In the Scenedesmus cell multiplication inhibition test, 68 potentially hazardous substances were examined to determine the effect concentrations (EC). The tests were conducted in accordance with the test procedure DIN 38 412, Part 9 (draft standard). The green alga Scenedesmus subspicatus CHODAT was cultivated as the test organism. Twenty-five substances were examined according to the standardized test procedure. The procedure was modified somewhat for the examination of volatile and/or strongly smelling substances. For 21 of the tested substances the concentrations for the 72 h and/or 48 h EBC10 values were in the concentration range 0.0001-2 mg1-1. Thus, they proved very/highly toxic to the cell multiplication of Scenedesmus subspicatus. When compared with the results of the 21d Daphina reproduction test, monobromoacetic, monochloroacetic acid, chloroacetaldehyde and chloramine T proved very harmful to green algae.","Results of the harmful effects of water pollutants to green algae (Scenedesmus subspicatus) in the cell multiplication inhibition test Abs: BIOSIS COPYRIGHT: BIOL ABS. In the Scenedesmus cell multiplication inhibition test, 68 potentially hazardous substances were examined to determine the effect concentrations (EC). The tests were conducted in accordance with the test procedure DIN 38 412, Part 9 (draft standard). The green alga Scenedesmus subspicatus CHODAT was cultivated as the test organism. Twenty-five substances were examined according to the standardized test procedure. The procedure was modified somewhat for the examination of volatile and/or strongly smelling substances. For 21 of the tested substances the concentrations for the 72 h and/or 48 h EBC10 values were in the concentration range 0.0001-2 mg1-1. Thus, they proved very/highly toxic to the cell multiplication of Scenedesmus subspicatus. When compared with the results of the 21d Daphina reproduction test, monobromoacetic, monochloroacetic acid, chloroacetaldehyde and chloramine T proved very harmful to green algae."
1023036,Lin et al. 1992,Analysis of residual amino acid–DNA crosslinks induced in intact cells by nickel and chromium compounds,"Chinese hamster ovary cells were incubated with radioactive amino acids, the DNA was isolated by standard proteinase K/phenol/chloroform extraction and residual amino acids complexed to the DNA were examined as an index of metal induced DNA-protein crosslinks. Using this method, both chromate and nickel caused residual histidine and cysteine to be complexed with the DNA isolated from metal-treated cells. In the case of chromate, a number of amino acids were studied and Tyr, Thr and Cys were found to be complexed to DNA at a level (above the untreated control) that was statistically significant. Stability studies indicated that some of the chromate-induced DNA-protein complexes were mediated by direct participation of chromium(III), whereas others that were resistant to dissociation by EDTA and mercaptoethanol did not seem to involve direct chromium(III) participation. A significant portion of the cysteine complexed to DNA by chromate was believed to involve glutathione since treatment of cells with cycloheximide did not decrease chromate-induced cysteine-DNA crosslinks. In the case of nickel, most of the stable DNA-protein crosslinks did not involve direct metal participation and were probably oxidatively mediated by Ni(II)/Ni(III) redox cycling. These findings present new methodology for analysis of DNA-protein crosslinks by examination of residual amino acids associated with the DNA. This method should be highly sensitive and will yield important information about the mechanism of metal-induced DNA-protein crosslinks.","Analysis of residual amino acid–DNA crosslinks induced in intact cells by nickel and chromium compounds Abs: Chinese hamster ovary cells were incubated with radioactive amino acids, the DNA was isolated by standard proteinase K/phenol/chloroform extraction and residual amino acids complexed to the DNA were examined as an index of metal induced DNA-protein crosslinks. Using this method, both chromate and nickel caused residual histidine and cysteine to be complexed with the DNA isolated from metal-treated cells. In the case of chromate, a number of amino acids were studied and Tyr, Thr and Cys were found to be complexed to DNA at a level (above the untreated control) that was statistically significant. Stability studies indicated that some of the chromate-induced DNA-protein complexes were mediated by direct participation of chromium(III), whereas others that were resistant to dissociation by EDTA and mercaptoethanol did not seem to involve direct chromium(III) participation. A significant portion of the cysteine complexed to DNA by chromate was believed to involve glutathione since treatment of cells with cycloheximide did not decrease chromate-induced cysteine-DNA crosslinks. In the case of nickel, most of the stable DNA-protein crosslinks did not involve direct metal participation and were probably oxidatively mediated by Ni(II)/Ni(III) redox cycling. These findings present new methodology for analysis of DNA-protein crosslinks by examination of residual amino acids associated with the DNA. This method should be highly sensitive and will yield important information about the mechanism of metal-induced DNA-protein crosslinks."
1022908,Teschke et al. 1999,"Occupational exposure to chemical and biological agents in the nonproduction departments of pulp, paper, and paper product mills: an international study","As part of an international epidemiological study of workers in the pulp and paper industry, previously unpublished exposure measurements were assembled in a database. This article describes 7293 measurements in nonproduction departments from 147 mills in 11 countries. The greatest variety of agents was measured in the maintenance, construction, and cleaning department, where high exposures to asbestos, chromium [VI] compounds, copper, mercury in urine, nitrogen dioxide, ozone, styrene, sulfur dioxide, trichloroethylene, and welding fumes were observed. Measurements in the storage, yard, loading, and shipping department indicated high exposures to asbestos, carbon monoxide, fungal spores, nitrogen oxides, sulfur dioxide, and total dust. The steam and power generation department had high exposures to methyl mercaptan, silica, and total dust. Measurements in process and effluent water treatment, laboratory and research, engineering, and office, administration, and cafeteria areas had few elevated exposures. Throughout the nonproduction departments, measurements of pulp-production chemicals such as chlorine and sulfur compounds tended to be low, with many below detection limits. There were some problems with the available data; in particular, detection limits were often not specified, and the data tended to be clustered in such a way that sources of exposure variability could not be distinguished. Despite these problems, the data provide new insight into the exposures of nonproduction pulp and paper industry personnel.","Occupational exposure to chemical and biological agents in the nonproduction departments of pulp, paper, and paper product mills: an international study Abs: As part of an international epidemiological study of workers in the pulp and paper industry, previously unpublished exposure measurements were assembled in a database. This article describes 7293 measurements in nonproduction departments from 147 mills in 11 countries. The greatest variety of agents was measured in the maintenance, construction, and cleaning department, where high exposures to asbestos, chromium [VI] compounds, copper, mercury in urine, nitrogen dioxide, ozone, styrene, sulfur dioxide, trichloroethylene, and welding fumes were observed. Measurements in the storage, yard, loading, and shipping department indicated high exposures to asbestos, carbon monoxide, fungal spores, nitrogen oxides, sulfur dioxide, and total dust. The steam and power generation department had high exposures to methyl mercaptan, silica, and total dust. Measurements in process and effluent water treatment, laboratory and research, engineering, and office, administration, and cafeteria areas had few elevated exposures. Throughout the nonproduction departments, measurements of pulp-production chemicals such as chlorine and sulfur compounds tended to be low, with many below detection limits. There were some problems with the available data; in particular, detection limits were often not specified, and the data tended to be clustered in such a way that sources of exposure variability could not be distinguished. Despite these problems, the data provide new insight into the exposures of nonproduction pulp and paper industry personnel."
1022612,Magara et al. 1996,The behavior of inorganic constituents and disinfection by products in reverse osmosis water desalination process,"BIOSIS COPYRIGHT: BIOL ABS. The countries and regions which suffer from the shortage of fresh water resources have developed sea and brackish water desalination plants to supply drinking water. The desalination process has usually been designed from the rejection ratio of salt to meet the level of soluble residue, chloride concentration for drinking purposes. The Japanese government revised the drinking water quality standards to enhance an appropriate drinking water quality management for many hazardous micro-pollutants in drinking water. Since there has not been sufficient studies on the performance of R.O. desalination processes on micro hazardous constituents, the authors carried out a pilot plant study and field study of several desalination plants for the public water supply. Most of the constituents of R.O. filtrate meets the drinking water quality standard under the design and operational condition that to attain 99% of the salt rejection. However, Langlier's index, boron and bromoform pro","The behavior of inorganic constituents and disinfection by products in reverse osmosis water desalination process Abs: BIOSIS COPYRIGHT: BIOL ABS. The countries and regions which suffer from the shortage of fresh water resources have developed sea and brackish water desalination plants to supply drinking water. The desalination process has usually been designed from the rejection ratio of salt to meet the level of soluble residue, chloride concentration for drinking purposes. The Japanese government revised the drinking water quality standards to enhance an appropriate drinking water quality management for many hazardous micro-pollutants in drinking water. Since there has not been sufficient studies on the performance of R.O. desalination processes on micro hazardous constituents, the authors carried out a pilot plant study and field study of several desalination plants for the public water supply. Most of the constituents of R.O. filtrate meets the drinking water quality standard under the design and operational condition that to attain 99% of the salt rejection. However, Langlier's index, boron and bromoform pro"
1022609,Hastings and  Miller 1997,OLFACTORY LOSS SECONDARY TO TOXIC EXPOSURE,BIOSIS COPYRIGHT: BIOL ABS. RRM BOOK CHAPTER HUMAN MOUSE RAT HAMSTER PATIENT ANIMAL MODEL OTOLARYNGOLOGY TOXICOLOGY OLFACTORY DYSFUNCTION TOXIC CHEMICALS CONCENTRATION THRESHOLD LIMIT VALUE PERMISSIBLE EXPOSURE LIMIT OSHA OCCUPATIONAL HEALTH TOXIC METALS HEAVY METALS IRRITANT GASES GASES SOLVENTS MULTIPLE CHEMICAL SENSITIVITY ETIOLOGY TOXICITY IMMUNE SYSTEM DISEASE,OLFACTORY LOSS SECONDARY TO TOXIC EXPOSURE Abs: BIOSIS COPYRIGHT: BIOL ABS. RRM BOOK CHAPTER HUMAN MOUSE RAT HAMSTER PATIENT ANIMAL MODEL OTOLARYNGOLOGY TOXICOLOGY OLFACTORY DYSFUNCTION TOXIC CHEMICALS CONCENTRATION THRESHOLD LIMIT VALUE PERMISSIBLE EXPOSURE LIMIT OSHA OCCUPATIONAL HEALTH TOXIC METALS HEAVY METALS IRRITANT GASES GASES SOLVENTS MULTIPLE CHEMICAL SENSITIVITY ETIOLOGY TOXICITY IMMUNE SYSTEM DISEASE
1022298,Dziewinski et al. 1998,"Development and testing electrochemical methods for treatment metal salts, cyanides and organic compounds in waste stream","BIOSIS COPYRIGHT: BIOL ABS. Electrochemical methods to process radioactive and hazardous (mixed) wastes were studied at a bench scale. Cadmium, copper, mercury, and chromium salts, cyanides, and simple organic compounds were used in the tests. Effective conditions were found to process these waste components by electrolysis. The equipment used in the tests included flow-through cells, a membrane cell, and a graphite packed bed cell. The tested methods included an open cell electrolysis, use of pulsating current, and mediated electrooxidation. The experiments demonstrated the feasibility of applying electrochemical systems to treat the studied waste components. The great advantage of electrochemical systems is that the treatment of various wastes, or streams containing selected waste components, can be accomplished in a single treatment unit. Additional advantages of electrochemical systems are their safety, ability to recycle, and the fact that they are inclined to receive a positive public percep","Development and testing electrochemical methods for treatment metal salts, cyanides and organic compounds in waste stream Abs: BIOSIS COPYRIGHT: BIOL ABS. Electrochemical methods to process radioactive and hazardous (mixed) wastes were studied at a bench scale. Cadmium, copper, mercury, and chromium salts, cyanides, and simple organic compounds were used in the tests. Effective conditions were found to process these waste components by electrolysis. The equipment used in the tests included flow-through cells, a membrane cell, and a graphite packed bed cell. The tested methods included an open cell electrolysis, use of pulsating current, and mediated electrooxidation. The experiments demonstrated the feasibility of applying electrochemical systems to treat the studied waste components. The great advantage of electrochemical systems is that the treatment of various wastes, or streams containing selected waste components, can be accomplished in a single treatment unit. Additional advantages of electrochemical systems are their safety, ability to recycle, and the fact that they are inclined to receive a positive public percep"
1022009,Chang et al. 2011,Heavy metal analysis of ortho MTA and ProRoot MTA,"<strong>INTRODUCTION: </strong>Recently, several kinds of mineral trioxide aggregate (MTA)-based products have been introduced in endodontics. Ortho MTA (BioMTA, Seoul, Republic of Korea) is one of those products, which was developed for retrograde filling, perforation repair, orthograde root canal obturation, and direct pulp capping. The inclusion of heavy metals in MTA-based materials is of concern because they come into direct contact with hard and soft tissues. The aim of this study was to investigate and compare the levels of arsenic (As), chromium (Cr), hexavalent chromium (Cr(6+)), and lead (Pb) in Ortho MTA and ProRoot MTA.<br /><br /><strong>METHODS: </strong>One gram of each MTA was digested using a mixture of hydrochloric and nitric acids and filtered. The As, Cr, and Pb in the resulting filtrates were analyzed by inductively coupled plasma-optical emission spectrometry. The level of Cr(6+) was measured by the methods suggested in the Korean Standard L 5221. The results were statistically analyzed using the Mann-Whitney U test.<br /><br /><strong>RESULTS: </strong>The concentration of As in ProRoot MTA was 1.16 ppm, but As was not detected in Ortho MTA. Cr(6+) and Pb were not detected in either MTA. Ortho MTA contained significantly less Cr than ProRoot MTA (P &lt; .05).<br /><br /><strong>CONCLUSIONS: </strong>Ortho MTA and ProRoot MTA meet the ISO specification 9917-1 regarding the safety limits of As and Pb and are safe biomaterials when the purity of As, Cr(6+), and Pb is considered.","Heavy metal analysis of ortho MTA and ProRoot MTA Abs: <strong>INTRODUCTION: </strong>Recently, several kinds of mineral trioxide aggregate (MTA)-based products have been introduced in endodontics. Ortho MTA (BioMTA, Seoul, Republic of Korea) is one of those products, which was developed for retrograde filling, perforation repair, orthograde root canal obturation, and direct pulp capping. The inclusion of heavy metals in MTA-based materials is of concern because they come into direct contact with hard and soft tissues. The aim of this study was to investigate and compare the levels of arsenic (As), chromium (Cr), hexavalent chromium (Cr(6+)), and lead (Pb) in Ortho MTA and ProRoot MTA.<br /><br /><strong>METHODS: </strong>One gram of each MTA was digested using a mixture of hydrochloric and nitric acids and filtered. The As, Cr, and Pb in the resulting filtrates were analyzed by inductively coupled plasma-optical emission spectrometry. The level of Cr(6+) was measured by the methods suggested in the Korean Standard L 5221. The results were statistically analyzed using the Mann-Whitney U test.<br /><br /><strong>RESULTS: </strong>The concentration of As in ProRoot MTA was 1.16 ppm, but As was not detected in Ortho MTA. Cr(6+) and Pb were not detected in either MTA. Ortho MTA contained significantly less Cr than ProRoot MTA (P &lt; .05).<br /><br /><strong>CONCLUSIONS: </strong>Ortho MTA and ProRoot MTA meet the ISO specification 9917-1 regarding the safety limits of As and Pb and are safe biomaterials when the purity of As, Cr(6+), and Pb is considered."
1021976,Johnson et al. 2011,"Concentrations of arsenic, chromium, and nickel in toenail samples from Appalachian Kentucky residents","Lung cancer rates in Appalachian Kentucky are almost twice national rates; colorectal cancer rates are also elevated. Although smoking prevalence is high, it does not explain all excess risk. The area is characterized by poverty, low educational attainment, and unemployment. Coal production is a major industry. Pyrite contaminants of coal contain established human carcinogens, arsenic (As), chromium (Cr), and nickel (Ni). We compared biological exposure to As, Cr, and Ni for adults living in Appalachian Kentucky with residents of Jefferson, a non-Appalachian, urban county. We further compared lung and colon cancer rates, demographics, and smoking prevalence across the study areas. Toenail clipping analysis measured As, Cr, and Ni for residents of 23 rural Appalachian Kentucky counties and for Jefferson County. Reverse Kaplan-Meier statistical methodology addressed left-censored data. Appalachian residents were exposed to higher concentrations of As, Cr, and Ni than Jefferson County residents. Lung cancer incidence and mortality rates in Appalachia are higher than Jefferson County and elsewhere in the state, as are colorectal mortality rates. Environmental factors may contribute to the increased concentration of trace elements measured in residents of the Appalachian region. Routes of human exposure need to be determined.","Concentrations of arsenic, chromium, and nickel in toenail samples from Appalachian Kentucky residents Abs: Lung cancer rates in Appalachian Kentucky are almost twice national rates; colorectal cancer rates are also elevated. Although smoking prevalence is high, it does not explain all excess risk. The area is characterized by poverty, low educational attainment, and unemployment. Coal production is a major industry. Pyrite contaminants of coal contain established human carcinogens, arsenic (As), chromium (Cr), and nickel (Ni). We compared biological exposure to As, Cr, and Ni for adults living in Appalachian Kentucky with residents of Jefferson, a non-Appalachian, urban county. We further compared lung and colon cancer rates, demographics, and smoking prevalence across the study areas. Toenail clipping analysis measured As, Cr, and Ni for residents of 23 rural Appalachian Kentucky counties and for Jefferson County. Reverse Kaplan-Meier statistical methodology addressed left-censored data. Appalachian residents were exposed to higher concentrations of As, Cr, and Ni than Jefferson County residents. Lung cancer incidence and mortality rates in Appalachia are higher than Jefferson County and elsewhere in the state, as are colorectal mortality rates. Environmental factors may contribute to the increased concentration of trace elements measured in residents of the Appalachian region. Routes of human exposure need to be determined."
1021580,El-Hasan et al. 2011,Cr(VI)/Cr(III) and As(V)/As(III) ratio assessments in Jordanian spent oil shale produced by aerobic combustion and Anaerobic Pyrolysis,"With the increase in the awareness of the public in the environmental impact of oil shale utilization, it is of interest to reveal the mobility of potentially toxic trace elements in spent oil shale. Therefore, the Cr and As oxidation state in a representative Jordanian oil shale sample from the El-Lajjoun area were investigated upon different lab-scale furnace treatments. The anaerobic pyrolysis was performed in a retort flushed by nitrogen gas at temperatures in between 600 and 800 °C (pyrolytic oil shale, POS). The aerobic combustion was simply performed in porcelain cups heated in a muffle furnace for 4 h at temperatures in between 700 and 1000 °C (burned oil shale, BOS). The high loss-on-ignition in the BOS samples of up to 370 g kg(-1) results from both calcium carbonate and organic carbon degradation. The LOI leads to enrichment in the Cr concentrations from 480 mg kg(-1) in the original oil shale up to 675 mg kg(-1) in the ? 850 °C BOS samples. Arsenic concentrations were not much elevated beyond that in the average shale standard (13 mg kg(-1)). Synchrotron-based X-ray absorption near-edge structure (XANES) analysis revealed that within the original oil shale the oxidation states of Cr and As were lower than after its aerobic combustion. Cr(VI) increased from 0% in the untreated or pyrolyzed oil shale up to 60% in the BOS ash combusted at 850 °C, while As(V) increased from 64% in the original oil shale up to 100% in the BOS ash at 700 °C. No Cr was released from original oil shale and POS products by the European compliance leaching test CEN/TC 292 EN 12457-1 (1:2 solid/water ratio, 24 h shaking), whereas leachates from BOS samples showed Cr release in the order of one mmol L(-1). The leachable Cr content is dominated by chromate as revealed by catalytic adsorptive stripping voltammetry (CAdSV) which could cause harmful contamination of surface and groundwater in the semiarid environment of Jordan.","Cr(VI)/Cr(III) and As(V)/As(III) ratio assessments in Jordanian spent oil shale produced by aerobic combustion and Anaerobic Pyrolysis Abs: With the increase in the awareness of the public in the environmental impact of oil shale utilization, it is of interest to reveal the mobility of potentially toxic trace elements in spent oil shale. Therefore, the Cr and As oxidation state in a representative Jordanian oil shale sample from the El-Lajjoun area were investigated upon different lab-scale furnace treatments. The anaerobic pyrolysis was performed in a retort flushed by nitrogen gas at temperatures in between 600 and 800 °C (pyrolytic oil shale, POS). The aerobic combustion was simply performed in porcelain cups heated in a muffle furnace for 4 h at temperatures in between 700 and 1000 °C (burned oil shale, BOS). The high loss-on-ignition in the BOS samples of up to 370 g kg(-1) results from both calcium carbonate and organic carbon degradation. The LOI leads to enrichment in the Cr concentrations from 480 mg kg(-1) in the original oil shale up to 675 mg kg(-1) in the ? 850 °C BOS samples. Arsenic concentrations were not much elevated beyond that in the average shale standard (13 mg kg(-1)). Synchrotron-based X-ray absorption near-edge structure (XANES) analysis revealed that within the original oil shale the oxidation states of Cr and As were lower than after its aerobic combustion. Cr(VI) increased from 0% in the untreated or pyrolyzed oil shale up to 60% in the BOS ash combusted at 850 °C, while As(V) increased from 64% in the original oil shale up to 100% in the BOS ash at 700 °C. No Cr was released from original oil shale and POS products by the European compliance leaching test CEN/TC 292 EN 12457-1 (1:2 solid/water ratio, 24 h shaking), whereas leachates from BOS samples showed Cr release in the order of one mmol L(-1). The leachable Cr content is dominated by chromate as revealed by catalytic adsorptive stripping voltammetry (CAdSV) which could cause harmful contamination of surface and groundwater in the semiarid environment of Jordan."
1021508,Wolf et al. 2011,"Simultaneous speciation of arsenic, selenium, and chromium: species stability, sample preservation, and analysis of ash and soil leachates","An analytical method using high-performance liquid chromatography separation with inductively coupled plasma mass spectrometry (ICP-MS) detection previously developed for the determination of Cr(III) and Cr(VI) has been adapted to allow the determination of As(III), As(V), Se(IV), Se(VI), Cr(III), and Cr(VI) under the same chromatographic conditions. Using this method, all six inorganic species can be determined in less than 3 min. A dynamic reaction cell (DRC)-ICP-MS system was used to detect the species eluted from the chromatographic column in order to reduce interferences. A variety of reaction cell gases and conditions may be utilized with the DRC-ICP-MS, and final selection of conditions is determined by data quality objectives. Results indicated all starting standards, reagents, and sample vials should be thoroughly tested for contamination. Tests on species stability indicated that refrigeration at 10 °C was preferential to freezing for most species, particularly when all species were present, and that sample solutions and extracts should be analyzed as soon as possible to eliminate species instability and interconversion effects. A variety of environmental and geological samples, including waters and deionized water [leachates] and simulated biological leachates from soils and wildfire ashes have been analyzed using this method. Analytical spikes performed on each sample were used to evaluate data quality. Speciation analyses were conducted on deionized water leachates and simulated lung fluid leachates of ash and soils impacted by wildfires. These results show that, for leachates containing high levels of total Cr, the majority of the chromium was present in the hexavalent Cr(VI) form. In general, total and hexavalent chromium levels for samples taken from burned residential areas were higher than those obtained from non-residential forested areas. Arsenic, when found, was generally in the more oxidized As(V) form. Selenium (IV) and (VI) were present, but typically at low levels.","Simultaneous speciation of arsenic, selenium, and chromium: species stability, sample preservation, and analysis of ash and soil leachates Abs: An analytical method using high-performance liquid chromatography separation with inductively coupled plasma mass spectrometry (ICP-MS) detection previously developed for the determination of Cr(III) and Cr(VI) has been adapted to allow the determination of As(III), As(V), Se(IV), Se(VI), Cr(III), and Cr(VI) under the same chromatographic conditions. Using this method, all six inorganic species can be determined in less than 3 min. A dynamic reaction cell (DRC)-ICP-MS system was used to detect the species eluted from the chromatographic column in order to reduce interferences. A variety of reaction cell gases and conditions may be utilized with the DRC-ICP-MS, and final selection of conditions is determined by data quality objectives. Results indicated all starting standards, reagents, and sample vials should be thoroughly tested for contamination. Tests on species stability indicated that refrigeration at 10 °C was preferential to freezing for most species, particularly when all species were present, and that sample solutions and extracts should be analyzed as soon as possible to eliminate species instability and interconversion effects. A variety of environmental and geological samples, including waters and deionized water [leachates] and simulated biological leachates from soils and wildfire ashes have been analyzed using this method. Analytical spikes performed on each sample were used to evaluate data quality. Speciation analyses were conducted on deionized water leachates and simulated lung fluid leachates of ash and soils impacted by wildfires. These results show that, for leachates containing high levels of total Cr, the majority of the chromium was present in the hexavalent Cr(VI) form. In general, total and hexavalent chromium levels for samples taken from burned residential areas were higher than those obtained from non-residential forested areas. Arsenic, when found, was generally in the more oxidized As(V) form. Selenium (IV) and (VI) were present, but typically at low levels."
1021361,Huggins et al. 2004,Quantifying hazardous species in particulate matter derived from fossil-fuel combustion,"An analysis protocol that combines X-ray absorption near-edge structure spectroscopy with selective leaching has been developed to examine hazardous species in size-segregated particulate matter (PM) samples derived from the combustion of fossil fuels. The protocol has been used to identify and determine quantitatively the amounts of three important toxic species in combustion-derived PM: viz., nickel sulfides in residual oil fly ash (ROFA) PM, and Cr(VI) and As(III) species in coal fly ash PM. Although it has been assumed that these toxic species might exist in PM derived from fossil-fuel combustion, the results presented here constitute the first direct determination of them in combustion-derived PM and their potential bioavailability. Detailed information on the presence of these toxic species in PM samples is of significant interest to epidemiological and toxicological studies of the health effects of both source and ambient PM. Additionally, information is obtained on insoluble forms that may be useful for source attribution and on the distribution of phases between size fractions that may be related to formation mechanisms of specific toxic species during combustion.","Quantifying hazardous species in particulate matter derived from fossil-fuel combustion Abs: An analysis protocol that combines X-ray absorption near-edge structure spectroscopy with selective leaching has been developed to examine hazardous species in size-segregated particulate matter (PM) samples derived from the combustion of fossil fuels. The protocol has been used to identify and determine quantitatively the amounts of three important toxic species in combustion-derived PM: viz., nickel sulfides in residual oil fly ash (ROFA) PM, and Cr(VI) and As(III) species in coal fly ash PM. Although it has been assumed that these toxic species might exist in PM derived from fossil-fuel combustion, the results presented here constitute the first direct determination of them in combustion-derived PM and their potential bioavailability. Detailed information on the presence of these toxic species in PM samples is of significant interest to epidemiological and toxicological studies of the health effects of both source and ambient PM. Additionally, information is obtained on insoluble forms that may be useful for source attribution and on the distribution of phases between size fractions that may be related to formation mechanisms of specific toxic species during combustion."
1021318,Kraus and  Müller-Lux 2004,[Occupation related thoracic tumors],"It is estimated that about 4% of cancer mortality is attributed to occupational risk factors. Due to long latency periods it is often difficult to establish causal relationships. Thoracal cancer accounts for about 88% of all compensated occupational cancers in Germany. Most important exposures and diseases are asbestos-related lung cancer, asbestos-related malignant mesothelioma and radiation induced lung cancer (by Radon and its decay products). Lung cancer caused by nickel compounds, hexavalent chromium, arsenic and its compounds, coke oven gases and polycyclic aromatic hydrocarbons are rare. Silica-dust induced lung cancer can be compensated as occupational disease if a silicosis is present. In Germany every physician is obliged to notify a suspected occupational cancer as well as other occupational diseases.","[Occupation related thoracic tumors] Abs: It is estimated that about 4% of cancer mortality is attributed to occupational risk factors. Due to long latency periods it is often difficult to establish causal relationships. Thoracal cancer accounts for about 88% of all compensated occupational cancers in Germany. Most important exposures and diseases are asbestos-related lung cancer, asbestos-related malignant mesothelioma and radiation induced lung cancer (by Radon and its decay products). Lung cancer caused by nickel compounds, hexavalent chromium, arsenic and its compounds, coke oven gases and polycyclic aromatic hydrocarbons are rare. Silica-dust induced lung cancer can be compensated as occupational disease if a silicosis is present. In Germany every physician is obliged to notify a suspected occupational cancer as well as other occupational diseases."
1021167,Rao et al. 2009,Protective role of vitamin E on nickel and/or chromium induced oxidative stress in the mouse ovary,"In the present study, we report the invivo effects of nickel chloride (NiCl2; 8 and 16 mg/kg body weight) and/or potassium dichromate (K2Cr2O7; 5 and 10mg/kg body weight) in the ovary of adult mice. The protective role of vitamin E (2mg/kg body weight) along with their combination was also studied. Nickel and/or chromium to mice enhanced the levels of lipid peroxides in the ovary, which was accompanied by a significant decline in the levels of protein, glutathione, total ascorbic acid and activities of superoxide dismutase and catalase. Supplementation of vitamin E along with NiCl2 + K2Cr2O7 significantly lowered the levels of lipid peroxidation and enhanced the antioxidant status. Findings of the present study suggest that vitamin E exerts its protective effect against nickel and/or chromium induced toxicity by preventing lipid peroxidation and protecting antioxidant system in the mouse ovary.","Protective role of vitamin E on nickel and/or chromium induced oxidative stress in the mouse ovary Abs: In the present study, we report the invivo effects of nickel chloride (NiCl2; 8 and 16 mg/kg body weight) and/or potassium dichromate (K2Cr2O7; 5 and 10mg/kg body weight) in the ovary of adult mice. The protective role of vitamin E (2mg/kg body weight) along with their combination was also studied. Nickel and/or chromium to mice enhanced the levels of lipid peroxides in the ovary, which was accompanied by a significant decline in the levels of protein, glutathione, total ascorbic acid and activities of superoxide dismutase and catalase. Supplementation of vitamin E along with NiCl2 + K2Cr2O7 significantly lowered the levels of lipid peroxidation and enhanced the antioxidant status. Findings of the present study suggest that vitamin E exerts its protective effect against nickel and/or chromium induced toxicity by preventing lipid peroxidation and protecting antioxidant system in the mouse ovary."
1020605,Martínez-Bravo et al. 2001,"Multielemental determination of arsenic, selenium and chromium(VI) species in water by high-performance liquid chromatography-inductively coupled plasma mass spectrometry","A new method for the simultaneous chromatographic separation and determination of arsenite, arsenate, mono-methylarsonic acid, dimethylarsinic acid, selenite, selenate and hexavalent chromium in water is presented. Speciation was achieved by on-line coupling of anion-exchange LC and inductively coupled plasma mass spectrometry (ICP-MS). Optimisation of the chromatographic conditions led to baseline separation of the seven species in 14 min using gradient elution with NH4NO3 20 mM, pH 8.7-NH4NO3 60 mM, pH 8.7 as mobile phase. Detection limits are in the range 40-60 ng l(-1) for arsenic species, around 130 ng l(-1) for Cr(VI), and higher for Se(IV) and Se(VI) (1.2 and 1.4 microg l(-1) respectively). The method showed good accuracy and repeatability, and no interference of chloride on 75As, 77Se or 53Cr was observed. The developed method was applied to the analysis of several environmental surface water samples.","Multielemental determination of arsenic, selenium and chromium(VI) species in water by high-performance liquid chromatography-inductively coupled plasma mass spectrometry Abs: A new method for the simultaneous chromatographic separation and determination of arsenite, arsenate, mono-methylarsonic acid, dimethylarsinic acid, selenite, selenate and hexavalent chromium in water is presented. Speciation was achieved by on-line coupling of anion-exchange LC and inductively coupled plasma mass spectrometry (ICP-MS). Optimisation of the chromatographic conditions led to baseline separation of the seven species in 14 min using gradient elution with NH4NO3 20 mM, pH 8.7-NH4NO3 60 mM, pH 8.7 as mobile phase. Detection limits are in the range 40-60 ng l(-1) for arsenic species, around 130 ng l(-1) for Cr(VI), and higher for Se(IV) and Se(VI) (1.2 and 1.4 microg l(-1) respectively). The method showed good accuracy and repeatability, and no interference of chloride on 75As, 77Se or 53Cr was observed. The developed method was applied to the analysis of several environmental surface water samples."
1020571,Cocco 2001,Multifactorial aetiology of lung cancer among silica-exposed workers,"In 1997, the International Agency for Research on Cancer (IARC) upgraded its evaluation of crystalline silica to a Group 1 human carcinogen. Criticism against such decision is based on the lack of consistency in experimental results across animal species, violation of an important principle for causality, such as the replication of findings under different circumstances of exposure, and the lack of a clear dose-response curve. The most recent epidemiological literature on the silica-silicosis-lung cancer link replicates the inconsistent findings that have been characterising 50 years of scientific debate in the occupational arena. Exposure circumstances capable of modifying the silica-lung cancer association include chronic bronchitis, composition of the dust mixing, particularly concerning co-occurrence of other known or probable lung carcinogens, total respirable dust, concentration of silica in respirable dust, type of crystalline silica and particle surface characteristics. The hypothesis of a silicosis-mediated pathway points toward an unspecific mechanism shared with other fibrotic conditions, for which silica might be just one of the triggers. In envisaging a multivariate multistep model of lung cancer among silica-exposed workers, silica might be considered as a &quot;passive components of the sufficient cause&quot;, i.e., one of the associated risk factors, concurrent or subsequent to the &quot;active component(s) of the sufficient cause&quot; (including, for instance, smoking, asbestos, radon-daughters, arsenic, hexavalent chromium, nickel, polycyclic aromatic hydrocarbons (PAH), and diesel exhausts among the external risk factors; and DNA repair enzymes polymorphism and spontaneous inactivation of tumour suppressor genes among the internal risk factors), which adds up in modulating the tumoral development in not easily predictable directions. If silica acts as a human lung carcinogen depending on certain occupational exposure circumstances, perhaps those circumstances and not silica itself should be classified for their human carcinogenicity potential.","Multifactorial aetiology of lung cancer among silica-exposed workers Abs: In 1997, the International Agency for Research on Cancer (IARC) upgraded its evaluation of crystalline silica to a Group 1 human carcinogen. Criticism against such decision is based on the lack of consistency in experimental results across animal species, violation of an important principle for causality, such as the replication of findings under different circumstances of exposure, and the lack of a clear dose-response curve. The most recent epidemiological literature on the silica-silicosis-lung cancer link replicates the inconsistent findings that have been characterising 50 years of scientific debate in the occupational arena. Exposure circumstances capable of modifying the silica-lung cancer association include chronic bronchitis, composition of the dust mixing, particularly concerning co-occurrence of other known or probable lung carcinogens, total respirable dust, concentration of silica in respirable dust, type of crystalline silica and particle surface characteristics. The hypothesis of a silicosis-mediated pathway points toward an unspecific mechanism shared with other fibrotic conditions, for which silica might be just one of the triggers. In envisaging a multivariate multistep model of lung cancer among silica-exposed workers, silica might be considered as a &quot;passive components of the sufficient cause&quot;, i.e., one of the associated risk factors, concurrent or subsequent to the &quot;active component(s) of the sufficient cause&quot; (including, for instance, smoking, asbestos, radon-daughters, arsenic, hexavalent chromium, nickel, polycyclic aromatic hydrocarbons (PAH), and diesel exhausts among the external risk factors; and DNA repair enzymes polymorphism and spontaneous inactivation of tumour suppressor genes among the internal risk factors), which adds up in modulating the tumoral development in not easily predictable directions. If silica acts as a human lung carcinogen depending on certain occupational exposure circumstances, perhaps those circumstances and not silica itself should be classified for their human carcinogenicity potential."
1020553,Shi et al. 2004,Oxidative stress and apoptosis in metal ion-induced carcinogenesis,"Epidemiological evidence suggests that exposure to certain metals causes carcinogenesis. The mechanisms of metal-induced carcinogenesis have been pursued in chemical, biochemical, cellular, and animal models. Significant evidence has accumulated that oxidative stress may be a common pathway in cellular responses to exposure to different metals. For example, in the last few years evidence in support of a correlation between the generation of reactive oxygen species, DNA damage, tumor promotion, and arsenic exposure has strengthened. This article summarizes the current literature on metal-mediated oxidative stress, apoptosis, and their relation to metal-mediated carcinogenesis, concentrating on arsenic and chromium.","Oxidative stress and apoptosis in metal ion-induced carcinogenesis Abs: Epidemiological evidence suggests that exposure to certain metals causes carcinogenesis. The mechanisms of metal-induced carcinogenesis have been pursued in chemical, biochemical, cellular, and animal models. Significant evidence has accumulated that oxidative stress may be a common pathway in cellular responses to exposure to different metals. For example, in the last few years evidence in support of a correlation between the generation of reactive oxygen species, DNA damage, tumor promotion, and arsenic exposure has strengthened. This article summarizes the current literature on metal-mediated oxidative stress, apoptosis, and their relation to metal-mediated carcinogenesis, concentrating on arsenic and chromium."
1020536,Chen et al. 2001,Cell apoptosis induced by carcinogenic metals,"Well-documented evidence suggests that environmental and occupational exposure of toxic metals or metal-containing compounds can cause a number of human diseases, including inflammation and cancer, through DNA damage, protein modifications, or lipid peroxidation. This mini-review addresses the mechanisms of cell death induced by some carcinogenic metals, including arsenic (III), chromium (VI) and vanadium (V). A possible contribution of reactive oxygen species to metal-induced cell death is also discussed.","Cell apoptosis induced by carcinogenic metals Abs: Well-documented evidence suggests that environmental and occupational exposure of toxic metals or metal-containing compounds can cause a number of human diseases, including inflammation and cancer, through DNA damage, protein modifications, or lipid peroxidation. This mini-review addresses the mechanisms of cell death induced by some carcinogenic metals, including arsenic (III), chromium (VI) and vanadium (V). A possible contribution of reactive oxygen species to metal-induced cell death is also discussed."
1020484,Kazi and  Cooper 2002,Rapid-extraction oxidation process to recover and reuse copper chromium and arsenic from industrial wood preservative sludge,"Chromated copper arsenate (CCA) wood preservative can form insoluble sludges when the hexavalent chromium component is reduced by wood extractives, wood particles and preservative additives in the solution. This sludge accumulates in treating solution work tanks, sumps and in-line filters and must be disposed of as hazardous wastes by waste disposal companies at high costs. A number of commercial sludges were investigated and found to contain 18-94% copper, chromium and arsenic as oxides combined with sand, oil, wood particles, additives and wood extractives. We have developed a multi-stage recycling process whereby approximately 97% of the CCA components are recovered from the sludge. It involves extraction with sodium hypochlorite to remove and oxidize chromium (more than 90%) and extract most of the arsenic (approx. 80%) followed by extraction of the copper and remaining arsenic and chromium with phosphoric acid. The phosphoric acid extract contains some trivalent chromium, which is subsequently oxidized by sodium hypochlorite. The combined oxidized extract containing CrVI, CuII and AsV was compatible with CCA treating solutions and could be re-used commercially for treating wood without having a significant effect on the preservative fixation rate or the leach resistance of the treated wood. A cost analysis showed that the economic savings from recovery of CCA chemicals and reduced landfill costs exceeded the variable costs for materials and energy for the process by as much as Can $966 per tonne of sludge if sodium sulfite can be acquired in bulk quantities for the process.","Rapid-extraction oxidation process to recover and reuse copper chromium and arsenic from industrial wood preservative sludge Abs: Chromated copper arsenate (CCA) wood preservative can form insoluble sludges when the hexavalent chromium component is reduced by wood extractives, wood particles and preservative additives in the solution. This sludge accumulates in treating solution work tanks, sumps and in-line filters and must be disposed of as hazardous wastes by waste disposal companies at high costs. A number of commercial sludges were investigated and found to contain 18-94% copper, chromium and arsenic as oxides combined with sand, oil, wood particles, additives and wood extractives. We have developed a multi-stage recycling process whereby approximately 97% of the CCA components are recovered from the sludge. It involves extraction with sodium hypochlorite to remove and oxidize chromium (more than 90%) and extract most of the arsenic (approx. 80%) followed by extraction of the copper and remaining arsenic and chromium with phosphoric acid. The phosphoric acid extract contains some trivalent chromium, which is subsequently oxidized by sodium hypochlorite. The combined oxidized extract containing CrVI, CuII and AsV was compatible with CCA treating solutions and could be re-used commercially for treating wood without having a significant effect on the preservative fixation rate or the leach resistance of the treated wood. A cost analysis showed that the economic savings from recovery of CCA chemicals and reduced landfill costs exceeded the variable costs for materials and energy for the process by as much as Can $966 per tonne of sludge if sodium sulfite can be acquired in bulk quantities for the process."
1019913,Hartwig 1998,Carcinogenicity of metal compounds: possible role of DNA repair inhibition,"Compounds of chromium, nickel, cadmium, cobalt and arsenic are well-known carcinogens. However, their mode of action is still not fully understood, since, with the exception of chromium(VI), direct genotoxic effects are rather weak and/or restricted to comparatively high concentrations. However, current evidence suggests that DNA repair systems are very sensitive targets for nickel(II), cadmium(II), cobalt(II) and arsenic(III), leading to a diminished removal of endogenous DNA lesions and of DNA damage induced by environmental agents, which in turn may increase the risk of tumor formation. Nevertheless, the underlying mechanisms are quite different, depending for example on the ability of toxic metal ions to compete with magnesium ions or to displace zinc ions in zinc finger structures of DNA repair enzymes.","Carcinogenicity of metal compounds: possible role of DNA repair inhibition Abs: Compounds of chromium, nickel, cadmium, cobalt and arsenic are well-known carcinogens. However, their mode of action is still not fully understood, since, with the exception of chromium(VI), direct genotoxic effects are rather weak and/or restricted to comparatively high concentrations. However, current evidence suggests that DNA repair systems are very sensitive targets for nickel(II), cadmium(II), cobalt(II) and arsenic(III), leading to a diminished removal of endogenous DNA lesions and of DNA damage induced by environmental agents, which in turn may increase the risk of tumor formation. Nevertheless, the underlying mechanisms are quite different, depending for example on the ability of toxic metal ions to compete with magnesium ions or to displace zinc ions in zinc finger structures of DNA repair enzymes."
1019774,French et al. 1997,Assessment of health risks due to hazardous air pollutant emissions from electric utilities,"Hazardous air pollutant (HAP) emissions from electric utilities were evaluated. Cancer risks, as well as noncancer effects, due to inhalation exposure were assessed for 67 HAPs. Also, cancer risks due to multipathway exposure to radionuclide emissions were assessed. In addition, an assessment of the fate of mercury (Hg) through various environmental media was included. Results suggest arsenic, chromium, and nickel are the HAPs that present the highest cancer risk due to inhalation exposure. For noncancer effects due to inhalation exposure, hydrogen chloride appears to present the greatest potential concern. The risks due to multipathway exposure to radionuclides are estimated to be of similar magnitude to the risks posed by inhalation of arsenic and nickel. Mercury is of potential concern for multipathway exposures because it persists in the environmental and bioaccumulates in the aquatic food web. The study suggests there is a plausible link between Hg emissions from utilities and the Hg found in soil, water, and freshwater fish.","Assessment of health risks due to hazardous air pollutant emissions from electric utilities Abs: Hazardous air pollutant (HAP) emissions from electric utilities were evaluated. Cancer risks, as well as noncancer effects, due to inhalation exposure were assessed for 67 HAPs. Also, cancer risks due to multipathway exposure to radionuclide emissions were assessed. In addition, an assessment of the fate of mercury (Hg) through various environmental media was included. Results suggest arsenic, chromium, and nickel are the HAPs that present the highest cancer risk due to inhalation exposure. For noncancer effects due to inhalation exposure, hydrogen chloride appears to present the greatest potential concern. The risks due to multipathway exposure to radionuclides are estimated to be of similar magnitude to the risks posed by inhalation of arsenic and nickel. Mercury is of potential concern for multipathway exposures because it persists in the environmental and bioaccumulates in the aquatic food web. The study suggests there is a plausible link between Hg emissions from utilities and the Hg found in soil, water, and freshwater fish."
1019668,Hamilton et al. 1998,Molecular basis for effects of carcinogenic heavy metals on inducible gene expression,"Certain forms of the heavy metals arsenic and chromium are considered human carcinogens, although they are believed to act through very different mechanisms. Chromium(VI) is believed to act as a classic and mutagenic agent, and DNA/chromatin appears to be the principal target for its effects. In contrast, arsenic(III) is considered nongenotoxic, but is able to target specific cellular proteins, principally through sulfhydryl interactions. We had previously shown that various genotoxic chemical carcinogens, including chromium (VI), preferentially altered expression of several inducible genes but had little or no effect on constitutive gene expression. We were therefore interested in whether these carcinogenic heavy metals might target specific but distinct sites within cells, leading to alterations in gene expression that might contribute to the carcinogenic process. Arsenic(III) and chromium(VI) each significantly altered both basal and hormone-inducible expression of a model inducible gene, phosphoenolpyruvate carboxykinase (PEPCK), at nonovertly toxic doses in the chick embryo in vivo and rat hepatoma H411E cells in culture. We have recently developed two parallel cell culture approaches for examining the molecular basis for these effects. First, we are examining the effects of heavy metals on expression and activation of specific transcription factors known to be involved in regulation of susceptible inducible genes, and have recently observed significant but different effects of arsenic(III) and chromium(VI) on nuclear transcription factor binding. Second, we have developed cell lines with stably integrated PEPCK promoter-luciferase reporter gene constructs to examine effects of heavy metals on promoter function, and have also recently seen profound effects induced by both chromium(VI) and arsenic(III) in this system. These model systems should enable us to be able to identify the critical cis (DNA) and trans (protein) cellular targets of heavy metal exposure leading to alterations in expression of specific susceptible genes. It is anticipated that such information will provide valuable insight into the mechanistic basis for these effects as well as provide sensitive molecular biomarkers for evaluating human exposure.","Molecular basis for effects of carcinogenic heavy metals on inducible gene expression Abs: Certain forms of the heavy metals arsenic and chromium are considered human carcinogens, although they are believed to act through very different mechanisms. Chromium(VI) is believed to act as a classic and mutagenic agent, and DNA/chromatin appears to be the principal target for its effects. In contrast, arsenic(III) is considered nongenotoxic, but is able to target specific cellular proteins, principally through sulfhydryl interactions. We had previously shown that various genotoxic chemical carcinogens, including chromium (VI), preferentially altered expression of several inducible genes but had little or no effect on constitutive gene expression. We were therefore interested in whether these carcinogenic heavy metals might target specific but distinct sites within cells, leading to alterations in gene expression that might contribute to the carcinogenic process. Arsenic(III) and chromium(VI) each significantly altered both basal and hormone-inducible expression of a model inducible gene, phosphoenolpyruvate carboxykinase (PEPCK), at nonovertly toxic doses in the chick embryo in vivo and rat hepatoma H411E cells in culture. We have recently developed two parallel cell culture approaches for examining the molecular basis for these effects. First, we are examining the effects of heavy metals on expression and activation of specific transcription factors known to be involved in regulation of susceptible inducible genes, and have recently observed significant but different effects of arsenic(III) and chromium(VI) on nuclear transcription factor binding. Second, we have developed cell lines with stably integrated PEPCK promoter-luciferase reporter gene constructs to examine effects of heavy metals on promoter function, and have also recently seen profound effects induced by both chromium(VI) and arsenic(III) in this system. These model systems should enable us to be able to identify the critical cis (DNA) and trans (protein) cellular targets of heavy metal exposure leading to alterations in expression of specific susceptible genes. It is anticipated that such information will provide valuable insight into the mechanistic basis for these effects as well as provide sensitive molecular biomarkers for evaluating human exposure."
1019501,Kaltreider et al. 1999,Differential effects of arsenic(III) and chromium(VI) on nuclear transcription factor binding,"The toxic metals arsenic(III) and chromium(VI) are considered human carcinogens, although they may act through different mechanisms. We previously showed that when administered at single low, non-overtly toxic doses, chromium, arsenic, and several other chemical carcinogens preferentially alter expression of several model inducible genes in both whole-animal and cell-culture systems. In this study, we assessed whether chromium and arsenic target specific signaling pathways within cells to selectively modulate gene expression. We examined the effects of non-cytotoxic and cytotoxic doses of arsenic(III) and chromium(VI) on nuclear binding of the transcription factors AP-1, NF-kappaB, Sp1, and YB-1 in human MDA-MB-435 breast cancer and rat H4IIE hepatoma cells. These transcription factors were chosen because they may regulate many inducible genes, including those previously shown to be altered by metal treatments. We report that both arsenic and chromium significantly altered nuclear binding levels of these factors to their respective cis-acting elements. However, there were qualitative and quantitative differences in these effects that were dependent on the metal, time, dose, transcription factor, and cell line. These effects may play a significant role in metal-induced alterations in gene expression.","Differential effects of arsenic(III) and chromium(VI) on nuclear transcription factor binding Abs: The toxic metals arsenic(III) and chromium(VI) are considered human carcinogens, although they may act through different mechanisms. We previously showed that when administered at single low, non-overtly toxic doses, chromium, arsenic, and several other chemical carcinogens preferentially alter expression of several model inducible genes in both whole-animal and cell-culture systems. In this study, we assessed whether chromium and arsenic target specific signaling pathways within cells to selectively modulate gene expression. We examined the effects of non-cytotoxic and cytotoxic doses of arsenic(III) and chromium(VI) on nuclear binding of the transcription factors AP-1, NF-kappaB, Sp1, and YB-1 in human MDA-MB-435 breast cancer and rat H4IIE hepatoma cells. These transcription factors were chosen because they may regulate many inducible genes, including those previously shown to be altered by metal treatments. We report that both arsenic and chromium significantly altered nuclear binding levels of these factors to their respective cis-acting elements. However, there were qualitative and quantitative differences in these effects that were dependent on the metal, time, dose, transcription factor, and cell line. These effects may play a significant role in metal-induced alterations in gene expression."
1019457,Anderson 1999,"RESEARCH: Comparison of Temporal Trends in Ambient and Compliance Trace Element and PCB Data in Pool 2 of the Mississippi River, USA, 1985-1995","/ The Intergovernmental Task Force on Monitoring has suggested studies on ambient (in-stream) and compliance (wastewater) data to determine if monitoring can be reduced locally or nationally. The similarity in temporal trends between retrospective ambient and compliance water-quality data collected from Pool 2 of the Mississippi River, USA, was determined for 1985-1995. Constituents studied included the following trace elements: arsenic (As), cadmium (Cd), chromium (Cr), hexavalent chromium (Cr(6+)), copper (Cu), lead (Pb), mercury (Hg), nickel (Ni), selenium (Se), zinc (Zn), and polychlorinated biphenyls (PCBs). Water-column, bed-sediment, and fish-tissue (fillets) data collected by five government agencies comprised the ambient data set; effluent data from five registered facilities comprised the compliance data set. The nonparametric Mann-Kendall trend test indicated that 33% of temporal trends in all data were statistically significant (P &lt; 0.05). Possible reasons for this were low sample sizes, and a high percentage of samples below the analytical detection limit. Trends in compliance data were more distinct; most trace elements decreased significantly, probably due to improvements in wastewater treatment. Seven trace elements (Cr, Cd, Cu, Pb, Hg, Ni, and Zn) had statistically significant decreases in wastewater and portions of either or both ambient water and bed sediment. No trends were found in fish tissue. Inconsistency in trends between ambient and compliance data were often found for individual constituents, making overall similarity between the data sets difficult to determine. Logistical differences in monitoring programs, such as varying field and laboratory methods among agencies, made it difficult to assess ambient temporal trends.KEY WORDS: Mann-Kendall trend test; Ambient data; Compliance data; Trace elements; PCBs, Mississippi Riverhttp://link.springer-ny.com/link/service/journals/00267/bibs/24n4p497.html&lt;/HEA","RESEARCH: Comparison of Temporal Trends in Ambient and Compliance Trace Element and PCB Data in Pool 2 of the Mississippi River, USA, 1985-1995 Abs: / The Intergovernmental Task Force on Monitoring has suggested studies on ambient (in-stream) and compliance (wastewater) data to determine if monitoring can be reduced locally or nationally. The similarity in temporal trends between retrospective ambient and compliance water-quality data collected from Pool 2 of the Mississippi River, USA, was determined for 1985-1995. Constituents studied included the following trace elements: arsenic (As), cadmium (Cd), chromium (Cr), hexavalent chromium (Cr(6+)), copper (Cu), lead (Pb), mercury (Hg), nickel (Ni), selenium (Se), zinc (Zn), and polychlorinated biphenyls (PCBs). Water-column, bed-sediment, and fish-tissue (fillets) data collected by five government agencies comprised the ambient data set; effluent data from five registered facilities comprised the compliance data set. The nonparametric Mann-Kendall trend test indicated that 33% of temporal trends in all data were statistically significant (P &lt; 0.05). Possible reasons for this were low sample sizes, and a high percentage of samples below the analytical detection limit. Trends in compliance data were more distinct; most trace elements decreased significantly, probably due to improvements in wastewater treatment. Seven trace elements (Cr, Cd, Cu, Pb, Hg, Ni, and Zn) had statistically significant decreases in wastewater and portions of either or both ambient water and bed sediment. No trends were found in fish tissue. Inconsistency in trends between ambient and compliance data were often found for individual constituents, making overall similarity between the data sets difficult to determine. Logistical differences in monitoring programs, such as varying field and laboratory methods among agencies, made it difficult to assess ambient temporal trends.KEY WORDS: Mann-Kendall trend test; Ambient data; Compliance data; Trace elements; PCBs, Mississippi Riverhttp://link.springer-ny.com/link/service/journals/00267/bibs/24n4p497.html&lt;/HEA"
1019148,Tully et al. 2000,"Effects of arsenic, cadmium, chromium, and lead on gene expression regulated by a battery of 13 different promoters in recombinant HepG2 cells","Toxic metals occur naturally at low concentrations throughout the environment, but are found in higher concentrations at many of the hazardous waste sites on the EPA Superfund list. As part of the Agency for Toxic Substances and Disease Registry (ATSDR) mandate to evaluate the toxicity of metals and mixtures, we chose four of the high-priority metal pollutants from ATSDR's HAZDAT list, including arsenic, cadmium, chromium, and lead, to test in a commercially developed assay system, CAT-Tox(L) (Xenometrix). This assay employs a battery of recombinant HepG2 cell lines to test the transcriptional activation capacity of xenobiotics in any of 13 different signal transduction pathways. Our specific aims were to identify metal-responsive promoters and determine whether the pattern of gene expression changed with a mixture of metals. Humic acid was used in all assays as a carrier to help solubilize the metals and, in all cases, the cells were exposed to the humic acid-metal mixture for 48 h. Humic acid alone, at 50-100 microM, showed moderate activation of the XRE promoter, but little other notable activity. As(V), at doses of 50-250 microM, produced a complex profile of activity showing significant dose-dependent induction of the hMTIIA, GST Ya, HSP70, FOS, XRE, NFkappaBRE, GADD153, p53RE, and CRE promoters. Pb(II) showed dose-related induction of the GST Ya, XRE, hMTIIA, GRP78, and CYP IA1 promoters at doses in the range of 12-100 microM. Cd(II), at 1.25-15 microM, yielded significant dose-dependent induction of hMTIIA, XRE, CYP IA1, GST Ya, HSP70, NFkappaBRE, and FOS. Whereas Cr(III) yielded small, though significant inductions of the CRE, FOS, GADD153, and XRE promoters only at the highest dose (750 microM), Cr(VI) produced significant dose-related inductions of the p53RE, FOS, NFkappaBRE, XRE, GADD45, HSP70, and CRE promoters at much lower doses, in the range of 5-10 microM. Assays testing serial dilutions of a mixture comprising 7.5 microM Cd(II), 750 microM Cr(III), and 100 microM Pb(II) (the combination of metals most frequently found at National Priority List sites) showed significant dose-dependent induction of the hMTIIA promoter, but failed to show dose-related induction of any other promoter and showed no evidence of synergistic activation of gene expression by the metals in this mixture. Our results thus show metal activation of gene expression through several previously unreported signal transduction pathways, including As(V) induction of GST Ya, FOS, XRE, NFkBRE, GADD153, p53RE, and CRE; Pb(II) induction of GST Ya, XRE, Cyp IA1, and GADD153; Cd(II) induction of NFkBRE, Cyp IA1, XRE, and GST Ya; and Cr(VI) induction of p53RE, XRE, GADD45, HSP70, and CRE promoters, and thus suggest new insights into the biochemical mechanisms of toxicity and carcinogenicity of metals. It is also an important finding that no evidence of synergistic activity was detected with the mixture of Cd(II), Cr(III), and Pb(II) tested in these assays.","Effects of arsenic, cadmium, chromium, and lead on gene expression regulated by a battery of 13 different promoters in recombinant HepG2 cells Abs: Toxic metals occur naturally at low concentrations throughout the environment, but are found in higher concentrations at many of the hazardous waste sites on the EPA Superfund list. As part of the Agency for Toxic Substances and Disease Registry (ATSDR) mandate to evaluate the toxicity of metals and mixtures, we chose four of the high-priority metal pollutants from ATSDR's HAZDAT list, including arsenic, cadmium, chromium, and lead, to test in a commercially developed assay system, CAT-Tox(L) (Xenometrix). This assay employs a battery of recombinant HepG2 cell lines to test the transcriptional activation capacity of xenobiotics in any of 13 different signal transduction pathways. Our specific aims were to identify metal-responsive promoters and determine whether the pattern of gene expression changed with a mixture of metals. Humic acid was used in all assays as a carrier to help solubilize the metals and, in all cases, the cells were exposed to the humic acid-metal mixture for 48 h. Humic acid alone, at 50-100 microM, showed moderate activation of the XRE promoter, but little other notable activity. As(V), at doses of 50-250 microM, produced a complex profile of activity showing significant dose-dependent induction of the hMTIIA, GST Ya, HSP70, FOS, XRE, NFkappaBRE, GADD153, p53RE, and CRE promoters. Pb(II) showed dose-related induction of the GST Ya, XRE, hMTIIA, GRP78, and CYP IA1 promoters at doses in the range of 12-100 microM. Cd(II), at 1.25-15 microM, yielded significant dose-dependent induction of hMTIIA, XRE, CYP IA1, GST Ya, HSP70, NFkappaBRE, and FOS. Whereas Cr(III) yielded small, though significant inductions of the CRE, FOS, GADD153, and XRE promoters only at the highest dose (750 microM), Cr(VI) produced significant dose-related inductions of the p53RE, FOS, NFkappaBRE, XRE, GADD45, HSP70, and CRE promoters at much lower doses, in the range of 5-10 microM. Assays testing serial dilutions of a mixture comprising 7.5 microM Cd(II), 750 microM Cr(III), and 100 microM Pb(II) (the combination of metals most frequently found at National Priority List sites) showed significant dose-dependent induction of the hMTIIA promoter, but failed to show dose-related induction of any other promoter and showed no evidence of synergistic activation of gene expression by the metals in this mixture. Our results thus show metal activation of gene expression through several previously unreported signal transduction pathways, including As(V) induction of GST Ya, FOS, XRE, NFkBRE, GADD153, p53RE, and CRE; Pb(II) induction of GST Ya, XRE, Cyp IA1, and GADD153; Cd(II) induction of NFkBRE, Cyp IA1, XRE, and GST Ya; and Cr(VI) induction of p53RE, XRE, GADD45, HSP70, and CRE promoters, and thus suggest new insights into the biochemical mechanisms of toxicity and carcinogenicity of metals. It is also an important finding that no evidence of synergistic activity was detected with the mixture of Cd(II), Cr(III), and Pb(II) tested in these assays."
1018858,Canivet et al. 2001,Toxicity and bioaccumulation of arsenic and chromium in epigean and hypogean freshwater macroinvertebrates,"Lethal toxicity levels of two inorganic water pollutants, chromium (Cr6+) and arsenic (As3+), were determined toward six freshwater macroinvertebrate species collected from a single field site. Crustaceans were represented by two amphipod species, an epigean one (Gammarus fossarum) and a hypogean one (Niphargus rhenorhodanensis), and by an isopod species (Asellus aquaticus). There were two insect larvae, Heptagenia sulphurea (Ephemeroptera) and Hydropsiche pellucidula (Trichoptera) and a snail, Physa fontinalis. Median lethal concentrations (LC50s) were determined over 96-h and 240-h periods for chromium and over a 240-h period for arsenic. Arsenic bioaccumulation was studied, too. The macroinvertebrates tested showed a wide range of sensitivity and bioaccumulation. A comparison between 96-h and 240-h experiments demonstrated that there was an increase in toxicity values following a longer time exposure for chromium. Also chromium was more toxic toward crustaceans than arsenic; conversely, arsenic was more toxic for the insect larvae and snail tested here. The lethal concentrations determined for the two metals were discussed and compared to results from other toxicity studies. The use of such macroinvertebrates, collected in the field and tested for longer exposure periods than within the standardized 96-h tests, should provide more suitable results for monitoring the general environmental quality of freshwater systems.","Toxicity and bioaccumulation of arsenic and chromium in epigean and hypogean freshwater macroinvertebrates Abs: Lethal toxicity levels of two inorganic water pollutants, chromium (Cr6+) and arsenic (As3+), were determined toward six freshwater macroinvertebrate species collected from a single field site. Crustaceans were represented by two amphipod species, an epigean one (Gammarus fossarum) and a hypogean one (Niphargus rhenorhodanensis), and by an isopod species (Asellus aquaticus). There were two insect larvae, Heptagenia sulphurea (Ephemeroptera) and Hydropsiche pellucidula (Trichoptera) and a snail, Physa fontinalis. Median lethal concentrations (LC50s) were determined over 96-h and 240-h periods for chromium and over a 240-h period for arsenic. Arsenic bioaccumulation was studied, too. The macroinvertebrates tested showed a wide range of sensitivity and bioaccumulation. A comparison between 96-h and 240-h experiments demonstrated that there was an increase in toxicity values following a longer time exposure for chromium. Also chromium was more toxic toward crustaceans than arsenic; conversely, arsenic was more toxic for the insect larvae and snail tested here. The lethal concentrations determined for the two metals were discussed and compared to results from other toxicity studies. The use of such macroinvertebrates, collected in the field and tested for longer exposure periods than within the standardized 96-h tests, should provide more suitable results for monitoring the general environmental quality of freshwater systems."
1018785,Lin et al. 1995,Arsenic speciation using capillary zone electrophoresis with indirect ultraviolet detection,"The toxicological or biological importance of many trace elements in biological and environmental samples depends to a great extent on their quantities as well as their oxidation states and chemical forms. In this work, arsenic species (arsenate, arsenite, dimethylarsinate [DMA], and monomethylarsonate [MMA]) are determined using capillary zone electrophoresis (CZE) with indirect ultraviolet absorption detection. Sodium chromate is used as an electrolyte solution and to provide the chromophore. The effect of the pH of the solution on the separation of species of interest is discussed. The absolute detection limits are 5.2, 3.5, 15.6, and 15.6 pg for arsenate, arsenite, monomethylarsonate, and dimethylarsinate, respectively. A solution extracted from coal fly ash is analyzed using this method. The arsenate concentration is determined to be 5 micrograms/g. Arsenite, monomethylarsonate, and dimethylarsinate are not found. The advantages of using CZE as an efficient and sensitive separation method are discussed.","Arsenic speciation using capillary zone electrophoresis with indirect ultraviolet detection Abs: The toxicological or biological importance of many trace elements in biological and environmental samples depends to a great extent on their quantities as well as their oxidation states and chemical forms. In this work, arsenic species (arsenate, arsenite, dimethylarsinate [DMA], and monomethylarsonate [MMA]) are determined using capillary zone electrophoresis (CZE) with indirect ultraviolet absorption detection. Sodium chromate is used as an electrolyte solution and to provide the chromophore. The effect of the pH of the solution on the separation of species of interest is discussed. The absolute detection limits are 5.2, 3.5, 15.6, and 15.6 pg for arsenate, arsenite, monomethylarsonate, and dimethylarsinate, respectively. A solution extracted from coal fly ash is analyzed using this method. The arsenate concentration is determined to be 5 micrograms/g. Arsenite, monomethylarsonate, and dimethylarsinate are not found. The advantages of using CZE as an efficient and sensitive separation method are discussed."
1018716,Durant et al. 1995,"Elevated incidence of childhood leukemia in Woburn, Massachusetts: NIEHS Superfund Basic Research Program searches for causes","Between 1966 and 1986, the childhood leukemia rate in Woburn, Massachusetts, was 4-fold higher than the national average. A multidisciplinary research team from MIT, which is being supported by the NIEHS Superfund Basic Research Program, has explored the possible importance of a temporal correlation between the period of elevated leukemia and a previously unrecognized mobilization of toxic metals from a waste disposal site in north Woburn. Residents of Woburn may have been exposed to arsenic (70 micrograms/l) and chromium (240 micrograms/l) at levels in excess of federal drinking water standards (50 micrograms/l for each metal) by consuming municipal groundwater contaminated with these metals. Research is currently underway a) to elucidate the mechanisms and the pathways by which these metals were transported from the waste disposal site to the drinking water supply; b) to determine the identity of the principal human cell mutagens in samples of aquifer materials collected from the site of the municipal supply wells; and c) to measure the extent of exposure and genetic change in residents who consumed the contaminated well water.","Elevated incidence of childhood leukemia in Woburn, Massachusetts: NIEHS Superfund Basic Research Program searches for causes Abs: Between 1966 and 1986, the childhood leukemia rate in Woburn, Massachusetts, was 4-fold higher than the national average. A multidisciplinary research team from MIT, which is being supported by the NIEHS Superfund Basic Research Program, has explored the possible importance of a temporal correlation between the period of elevated leukemia and a previously unrecognized mobilization of toxic metals from a waste disposal site in north Woburn. Residents of Woburn may have been exposed to arsenic (70 micrograms/l) and chromium (240 micrograms/l) at levels in excess of federal drinking water standards (50 micrograms/l for each metal) by consuming municipal groundwater contaminated with these metals. Research is currently underway a) to elucidate the mechanisms and the pathways by which these metals were transported from the waste disposal site to the drinking water supply; b) to determine the identity of the principal human cell mutagens in samples of aquifer materials collected from the site of the municipal supply wells; and c) to measure the extent of exposure and genetic change in residents who consumed the contaminated well water."
1018706,Gonzalez et al. 1995,Inorganic pentavalent arsenic methylation by rats: effect of concentration and dichromate,"The effect of the administered arsenic (As) dose and the dichromate ion (Cr) on the methylation process of arsenic was studied in rats exposed to arsenate to elucidate the biotransformation of As. After oral administration of different As (V) and Cr (VI) concentrations, the different As metabolites (inorganic, methylarsonic acid [MMA] and dimethylarsinic acid [DMA] were separated by cation-exchange chromatography and measured by atomic absorption spectrophotometry. Administration of high doses of As produced enzymatic saturation and non-enzymatic depletion, with decreases in DMA levels. The presence of the dichromate ion supported arsenate methylation as it favored reduction of As (V) to As (III), but Cr (VI) produced a significant decrease in the total As excreted.","Inorganic pentavalent arsenic methylation by rats: effect of concentration and dichromate Abs: The effect of the administered arsenic (As) dose and the dichromate ion (Cr) on the methylation process of arsenic was studied in rats exposed to arsenate to elucidate the biotransformation of As. After oral administration of different As (V) and Cr (VI) concentrations, the different As metabolites (inorganic, methylarsonic acid [MMA] and dimethylarsinic acid [DMA] were separated by cation-exchange chromatography and measured by atomic absorption spectrophotometry. Administration of high doses of As produced enzymatic saturation and non-enzymatic depletion, with decreases in DMA levels. The presence of the dichromate ion supported arsenate methylation as it favored reduction of As (V) to As (III), but Cr (VI) produced a significant decrease in the total As excreted."
1018667,Kowalski et al. 1996,Arsenic and chromium enhance transformation of bovine papillomavirus DNA-transfected C3H/10T1/2 cells,"Tumor promoters such as phorbol esters, teleocidin and okadaic acid increase the numbers of multilayered, transformed foci produced by BPV DNA-transfected C3H/10T1/2 cells. We questioned whether arsenic and chromium, which are known human carcinogens also enhance transformation of BPV DNA-transfected C3H/10T1/2 cells. Cr(III) potassium sulfate at 100 microM enhanced transformation by 1.4-fold, but Cr(VI) as potassium chromate did not enhance transformation, although toxicity of potassium chromate may have prevented enhancement of transformation. Sodium arsenite (As(III) at 5 microM and sodium arsenate (As(V)) at 25 microM both enhanced neoplastic transformation by 6-fold. By comparison, in previous studies, sodium orthovanadate (V(IV)) or vanadyl sulfate (V(IV)) at 4 microM enhanced numbers of transformed foci by 25-50-fold. The comparatively strong enhancement of transformation by vanadium and phorbol esters suggests that neoplastic transformation may occur by mechanisms that are common to these compounds including alteration of tyrosine phosphorylation.","Arsenic and chromium enhance transformation of bovine papillomavirus DNA-transfected C3H/10T1/2 cells Abs: Tumor promoters such as phorbol esters, teleocidin and okadaic acid increase the numbers of multilayered, transformed foci produced by BPV DNA-transfected C3H/10T1/2 cells. We questioned whether arsenic and chromium, which are known human carcinogens also enhance transformation of BPV DNA-transfected C3H/10T1/2 cells. Cr(III) potassium sulfate at 100 microM enhanced transformation by 1.4-fold, but Cr(VI) as potassium chromate did not enhance transformation, although toxicity of potassium chromate may have prevented enhancement of transformation. Sodium arsenite (As(III) at 5 microM and sodium arsenate (As(V)) at 25 microM both enhanced neoplastic transformation by 6-fold. By comparison, in previous studies, sodium orthovanadate (V(IV)) or vanadyl sulfate (V(IV)) at 4 microM enhanced numbers of transformed foci by 25-50-fold. The comparatively strong enhancement of transformation by vanadium and phorbol esters suggests that neoplastic transformation may occur by mechanisms that are common to these compounds including alteration of tyrosine phosphorylation."
1018620,Hughes et al. 1995,Speciation in health risk assessments of metals: evaluation of effects associated with forms present in the environment,"Because metals occur in various forms in the environment, speciation is an issue which must be addressed in regulatory health risk assessment programs. The manner in which speciation was addressed in a federal program in Canada is discussed in this article. Under the Canadian Environmental Protection Act, four metals, including arsenic, cadmium, chromium, and nickel, and their compounds were assessed as priority substances to determine the risk to human health associated with exposure to levels present in the general environment in Canada. The extent to which the speciation of these metals could be considered in these assessments was largely determined by the nature of available data. Very few data were identified on speciation in environmental media to which humans are exposed. Based on available data on health effects, it was possible to conduct assessments on only one form each of arsenic and cadmium (i.e., inorganic arsenic and inorganic cadmium), two forms of chromium (trivalent and hexavalent), and four forms of inorganic nickel (oxidic, sulfidic, soluble, and metallic.","Speciation in health risk assessments of metals: evaluation of effects associated with forms present in the environment Abs: Because metals occur in various forms in the environment, speciation is an issue which must be addressed in regulatory health risk assessment programs. The manner in which speciation was addressed in a federal program in Canada is discussed in this article. Under the Canadian Environmental Protection Act, four metals, including arsenic, cadmium, chromium, and nickel, and their compounds were assessed as priority substances to determine the risk to human health associated with exposure to levels present in the general environment in Canada. The extent to which the speciation of these metals could be considered in these assessments was largely determined by the nature of available data. Very few data were identified on speciation in environmental media to which humans are exposed. Based on available data on health effects, it was possible to conduct assessments on only one form each of arsenic and cadmium (i.e., inorganic arsenic and inorganic cadmium), two forms of chromium (trivalent and hexavalent), and four forms of inorganic nickel (oxidic, sulfidic, soluble, and metallic."
1018386,Kachinskas et al. 1997,Arsenate suppression of human keratinocyte programming,"The human keratinocyte line SCC-9 has been used as a model for arsenate-induced perturbations of differentiation. Growth of these cells in 10 microM arsenate permitted the cultures to reach confluence, but prevented expression of 6 markers of suprabasal differentiation (involucrin, loricrin, filaggrin, spr 1, keratin 1 and keratin 10) as assayed by Northern blotting. By contrast, only slight alterations in mRNA levels were observed for one differentiation marker (keratinocyte transglutaminase) and for keratin 5, keratin 14, AP2 or glyceraldehyde phosphate dehydrogenase. The transition metal oxyanions vanadate and chromate had essentially the same suppressive effect on these markers as arsenate, while chronic treatment with tetradecanoylphorbol acetate was generally less effective in suppressing differentiation. To determine whether the previously observed arsenate-mediated alteration in AP1 and AP2 activities could account for the suppression of involucrin, a promoter analysis was conducted. Putative AP1 and AP2 response elements were identified in regions important for transcriptional activity of the 5'-flanking DNA. Mutations in two AP1 sites and one AP2 site were observed to decrease promoter activity significantly, and in combination, to reduce it to approximately 10% of that conferred by the native sequence. These results lend support to the working hypothesis that arsenate suppresses involucrin expression, and, more generally, keratinocyte programming, by altering the transcription factors AP1 and AP2.","Arsenate suppression of human keratinocyte programming Abs: The human keratinocyte line SCC-9 has been used as a model for arsenate-induced perturbations of differentiation. Growth of these cells in 10 microM arsenate permitted the cultures to reach confluence, but prevented expression of 6 markers of suprabasal differentiation (involucrin, loricrin, filaggrin, spr 1, keratin 1 and keratin 10) as assayed by Northern blotting. By contrast, only slight alterations in mRNA levels were observed for one differentiation marker (keratinocyte transglutaminase) and for keratin 5, keratin 14, AP2 or glyceraldehyde phosphate dehydrogenase. The transition metal oxyanions vanadate and chromate had essentially the same suppressive effect on these markers as arsenate, while chronic treatment with tetradecanoylphorbol acetate was generally less effective in suppressing differentiation. To determine whether the previously observed arsenate-mediated alteration in AP1 and AP2 activities could account for the suppression of involucrin, a promoter analysis was conducted. Putative AP1 and AP2 response elements were identified in regions important for transcriptional activity of the 5'-flanking DNA. Mutations in two AP1 sites and one AP2 site were observed to decrease promoter activity significantly, and in combination, to reduce it to approximately 10% of that conferred by the native sequence. These results lend support to the working hypothesis that arsenate suppresses involucrin expression, and, more generally, keratinocyte programming, by altering the transcription factors AP1 and AP2."
1017442,Saikia et al. 2011,Efficient removal of chromate and arsenate from individual and mixed system by malachite nanoparticles,"Malachite nanoparticles of 100-150 nm have been efficiently and for the first time used as an adsorbent for the removal of toxic arsenate and chromate. We report a high adsorption capacity for chromate and arsenate on malachite nanoparticle from both individual and mixed solution in pH ?4-5. However, the adsorption efficiency decreases with the increase of solution pH. Batch studies revealed that initial pH, temperature, malachite nanoparticles dose and initial concentration of chromate and arsenate were important parameters for the adsorption process. Thermodynamic analysis showed that adsorption of chromate and arsenate on malachite nanoparticles is endothermic and spontaneous. The adsorption of these anions has also been investigated quantitatively with the help of adsorption kinetics, isotherm, and selectivity coefficient (K) analysis. The adsorption data for both chromate and arsenate were fitted well in Langmuir isotherm and preferentially followed the second order kinetics. The binding affinity of chromate is found to be slightly higher than arsenate in a competitive adsorption process which leads to the comparatively higher adsorption of chromate on malachite nanoparticles surface.","Efficient removal of chromate and arsenate from individual and mixed system by malachite nanoparticles Abs: Malachite nanoparticles of 100-150 nm have been efficiently and for the first time used as an adsorbent for the removal of toxic arsenate and chromate. We report a high adsorption capacity for chromate and arsenate on malachite nanoparticle from both individual and mixed solution in pH ?4-5. However, the adsorption efficiency decreases with the increase of solution pH. Batch studies revealed that initial pH, temperature, malachite nanoparticles dose and initial concentration of chromate and arsenate were important parameters for the adsorption process. Thermodynamic analysis showed that adsorption of chromate and arsenate on malachite nanoparticles is endothermic and spontaneous. The adsorption of these anions has also been investigated quantitatively with the help of adsorption kinetics, isotherm, and selectivity coefficient (K) analysis. The adsorption data for both chromate and arsenate were fitted well in Langmuir isotherm and preferentially followed the second order kinetics. The binding affinity of chromate is found to be slightly higher than arsenate in a competitive adsorption process which leads to the comparatively higher adsorption of chromate on malachite nanoparticles surface."
1017369,Boffetta et al. 2011,"Occupational exposure to arsenic, cadmium, chromium, lead and nickel, and renal cell carcinoma: a case-control study from Central and Eastern Europe","<strong>OBJECTIVES: </strong>To investigate the risk of renal cell carcinoma (RCC) in Central and Eastern Europe in relation to exposure to known and suspected carcinogenic metals.<br /><br /><strong>METHODS: </strong>During 1999-2003, the authors conducted a hospital-based study in Czech Republic, Poland, Romania and Russia, including 1097 cases of RCC and 1476 controls. Occupational exposure to arsenic, cadmium, chromium(III), chromium(VI), lead and nickel was assessed by teams of local industrial hygiene experts, based on detailed occupational questionnaires.<br /><br /><strong>RESULTS: </strong>The ORs for RCC were 1.55 (95% CI 1.09 to 2.21) for exposure to lead and 1.40 (95% CI 0.69 to 2.85) for exposure to cadmium. No clear monotonic exposure-response relation was apparent for either duration of exposure or cumulative exposure to either metal, although the OR for the highest category of cumulative exposure to lead was 2.25 (95% CI 1.21 to 4.19). Exposure to other metals did not entail an increased risk of RCC.<br /><br /><strong>CONCLUSIONS: </strong>For cadmium, the lack of statistical significance of most results, potential confounding and the absence of clear dose-response relations suggest that an association with RCC is unlikely to be causal. In the case of lead, however, the elevated risk in the category of highest cumulative exposure is noteworthy and justifies further investigation.","Occupational exposure to arsenic, cadmium, chromium, lead and nickel, and renal cell carcinoma: a case-control study from Central and Eastern Europe Abs: <strong>OBJECTIVES: </strong>To investigate the risk of renal cell carcinoma (RCC) in Central and Eastern Europe in relation to exposure to known and suspected carcinogenic metals.<br /><br /><strong>METHODS: </strong>During 1999-2003, the authors conducted a hospital-based study in Czech Republic, Poland, Romania and Russia, including 1097 cases of RCC and 1476 controls. Occupational exposure to arsenic, cadmium, chromium(III), chromium(VI), lead and nickel was assessed by teams of local industrial hygiene experts, based on detailed occupational questionnaires.<br /><br /><strong>RESULTS: </strong>The ORs for RCC were 1.55 (95% CI 1.09 to 2.21) for exposure to lead and 1.40 (95% CI 0.69 to 2.85) for exposure to cadmium. No clear monotonic exposure-response relation was apparent for either duration of exposure or cumulative exposure to either metal, although the OR for the highest category of cumulative exposure to lead was 2.25 (95% CI 1.21 to 4.19). Exposure to other metals did not entail an increased risk of RCC.<br /><br /><strong>CONCLUSIONS: </strong>For cadmium, the lack of statistical significance of most results, potential confounding and the absence of clear dose-response relations suggest that an association with RCC is unlikely to be causal. In the case of lead, however, the elevated risk in the category of highest cumulative exposure is noteworthy and justifies further investigation."
1017243,Kim and  Choi 2011,Enhanced redox conversion of chromate and arsenite in ice,"The redox transformation of trace elements is critically affected by properties of the environmental media. While the environmentally important redox chemical reactions in aquatic environments have been extensively studied, those in the ice phase have been studied in only a few cases. In this work, chromium and arsenic species were selected as the model inorganic oxyanion contaminants for the study of redox chemical transformation in ice. We investigated (1) the reduction of hexavalent Cr(VI) (as chromate) by model organic acids (e.g., citric and oxalic acid) and (2) the simultaneous removal of Cr(VI) and As(III) (as arsenite) in ice phase in comparison with their counterparts in aqueous solution. The reduction of Cr(VI) by various organic acids (electron donors) was negligible in ambient aqueous solution but was significantly accelerated in ice. The simultaneous reduction of Cr(VI) and oxidation of As(III) in ice phase proceeded stoichiometrically, whereas their mutual conversion was insignificant in aqueous solution. The enhanced redox conversion of Cr(VI)/As(III) in ice is ascribed to the freeze concentration of both electron donors (e.g., organic acids, arsenites) and protons in the ice crystal grain boundaries. When the concentrations of both electron donors and protons were highly raised to an extreme, the removal rates of Cr(VI) in aqueous solution approached to those in ice. This specific combination of Cr(VI)/As(III) redox couple may provide an example that represents innumerable redox conversion reactions that could be greatly accelerated in ice/snow-covered or frozen environments.","Enhanced redox conversion of chromate and arsenite in ice Abs: The redox transformation of trace elements is critically affected by properties of the environmental media. While the environmentally important redox chemical reactions in aquatic environments have been extensively studied, those in the ice phase have been studied in only a few cases. In this work, chromium and arsenic species were selected as the model inorganic oxyanion contaminants for the study of redox chemical transformation in ice. We investigated (1) the reduction of hexavalent Cr(VI) (as chromate) by model organic acids (e.g., citric and oxalic acid) and (2) the simultaneous removal of Cr(VI) and As(III) (as arsenite) in ice phase in comparison with their counterparts in aqueous solution. The reduction of Cr(VI) by various organic acids (electron donors) was negligible in ambient aqueous solution but was significantly accelerated in ice. The simultaneous reduction of Cr(VI) and oxidation of As(III) in ice phase proceeded stoichiometrically, whereas their mutual conversion was insignificant in aqueous solution. The enhanced redox conversion of Cr(VI)/As(III) in ice is ascribed to the freeze concentration of both electron donors (e.g., organic acids, arsenites) and protons in the ice crystal grain boundaries. When the concentrations of both electron donors and protons were highly raised to an extreme, the removal rates of Cr(VI) in aqueous solution approached to those in ice. This specific combination of Cr(VI)/As(III) redox couple may provide an example that represents innumerable redox conversion reactions that could be greatly accelerated in ice/snow-covered or frozen environments."
1017120,Holmes and  Wise 2010,Mechanisms of metal-induced centrosome amplification,"Exposure to toxic and carcinogenic metals is widespread; however, their mechanisms of action remain largely unknown. One potential mechanism for metal-induced carcinogenicity and toxicity is centrosome amplification. Here we review the mechanisms for metal-induced centrosome amplification, including arsenic, chromium, mercury and nano-titanium dioxide.","Mechanisms of metal-induced centrosome amplification Abs: Exposure to toxic and carcinogenic metals is widespread; however, their mechanisms of action remain largely unknown. One potential mechanism for metal-induced carcinogenicity and toxicity is centrosome amplification. Here we review the mechanisms for metal-induced centrosome amplification, including arsenic, chromium, mercury and nano-titanium dioxide."
1016975,Rizki et al. 2002,Influence of sodium arsenite on the genotoxicity of potassium dichromate and ethyl methanesulfonate: studies with the wing spot test in Drosophila,"The wing spot test in Drosophila melanogaster was used to investigate the genotoxicity of arsenic and its effects on the action of two clearly genotoxic agents: potassium dichromate (PDC) and ethyl methanesulfonate (EMS). This assay is based on the principle that the loss of heterozygosity of the suitable recessive markers multiple wing hairs (mwh) and flare-3 (flr(3)) can lead to the formation of mutant clones of larval cells, which are then expressed as spots on the wings of adult flies. These spots can be attributed to different genotoxic events: either mitotic recombination or mutation (deletion, point mutation, and specific types of translocation). Pretreatments and chronic cotreatments were comparatively used for combined treatments. From the results obtained it is evident that sodium arsenite (SA) does not increase the frequency of any of the three categories of spots recorded (small, large, and twin spots) at the concentrations tested. The effects of SA in combination with PDC, in both cotreatments and pretreatments, indicate that SA almost suppressed the clones induced by PDC. Nevertheless, no effects of arsenic were observed with respect to the pre- and cotreatments with EMS. Thus, SA does not modify the frequencies of mutant clones induced by EMS.","Influence of sodium arsenite on the genotoxicity of potassium dichromate and ethyl methanesulfonate: studies with the wing spot test in Drosophila Abs: The wing spot test in Drosophila melanogaster was used to investigate the genotoxicity of arsenic and its effects on the action of two clearly genotoxic agents: potassium dichromate (PDC) and ethyl methanesulfonate (EMS). This assay is based on the principle that the loss of heterozygosity of the suitable recessive markers multiple wing hairs (mwh) and flare-3 (flr(3)) can lead to the formation of mutant clones of larval cells, which are then expressed as spots on the wings of adult flies. These spots can be attributed to different genotoxic events: either mitotic recombination or mutation (deletion, point mutation, and specific types of translocation). Pretreatments and chronic cotreatments were comparatively used for combined treatments. From the results obtained it is evident that sodium arsenite (SA) does not increase the frequency of any of the three categories of spots recorded (small, large, and twin spots) at the concentrations tested. The effects of SA in combination with PDC, in both cotreatments and pretreatments, indicate that SA almost suppressed the clones induced by PDC. Nevertheless, no effects of arsenic were observed with respect to the pre- and cotreatments with EMS. Thus, SA does not modify the frequencies of mutant clones induced by EMS."
1016624,Pourahmad et al. 2003,Carcinogenic metal induced sites of reactive oxygen species formation in hepatocytes,"Severe chronic liver disease results from the hepatic accumulation of copper nickel, cobalt or iron in humans and on the other hand cadmium, dichromate and arsenic may induce lung or kidney cancer. Acute or chronic CdCl2, HgCl2 or dichromate administration induces hepatic and nephrotoxicity in rodents. Oxidative stress is often cited as a possible cause but has not yet been measured. For the first time we have measured the reactive oxygen species (ROS) formation induced when cells are incubated with metals and determined its source. Hepatocytes incubated with 2',7'-dichlorofluorescin diacetate resulted in its rapid uptake and deacetylation by intracellular esterases to form 2',7'-dichlorofluorescin. A marked increase in ROS formation occurred with LD50 concentrations of cadmium [Cd(II)], Hg(II) or arsenite [As(III)] which was released by proton ionophores that uncouple oxidative phosphorylation. Uncouplers or oxidative phosphorylation also inhibited ROS formation induced by these metals, which suggests that mitochondria are major contributors to endogenous ROS formation. Glycolytic substrates also inhibited Cd(II)/Hg(II)/As(III)-induced ROS formation and confirms that mitochondria are the site of ROS formation. By contrast ROS formation by LD50 concentrations of Cu(II), Ni(II), Co(II) or dichromate [Cr(VI)] were not affected by uncouplers or glycolytic substrates. However they were inhibited by lysosomotropic agents or endogenous inhibitors [in contrast to Hg(II), Cd(II) or As(III)]. Furthermore Cu(II), Ni(II), Co(II) or Cr(VI) accumulated in the lysosomes and the ROS formed caused a loss of lysosomal membrane integrity. The release of lysosomal proteases and phospholipases also contributed to hepatocyte cytotoxicity. ROS formation and cytotoxicity induced by added H2O2 or generated by the intracellular redox cycling of nitrofurantoin was also inhibited by lysosomotropic agents and ferric chelators suggesting that lysosomal Fe(II) contributes to H2O2-induced cytotoxicity. In conclusion, lysosomes are sites of cytotoxic ROS formation with redox transition metals (CuII, CrVI, NiII, CoII) whereas mitochondria are the ROS sites for non-redox or poor redox cycling transition metals (CdII, HgII, AsIII).","Carcinogenic metal induced sites of reactive oxygen species formation in hepatocytes Abs: Severe chronic liver disease results from the hepatic accumulation of copper nickel, cobalt or iron in humans and on the other hand cadmium, dichromate and arsenic may induce lung or kidney cancer. Acute or chronic CdCl2, HgCl2 or dichromate administration induces hepatic and nephrotoxicity in rodents. Oxidative stress is often cited as a possible cause but has not yet been measured. For the first time we have measured the reactive oxygen species (ROS) formation induced when cells are incubated with metals and determined its source. Hepatocytes incubated with 2',7'-dichlorofluorescin diacetate resulted in its rapid uptake and deacetylation by intracellular esterases to form 2',7'-dichlorofluorescin. A marked increase in ROS formation occurred with LD50 concentrations of cadmium [Cd(II)], Hg(II) or arsenite [As(III)] which was released by proton ionophores that uncouple oxidative phosphorylation. Uncouplers or oxidative phosphorylation also inhibited ROS formation induced by these metals, which suggests that mitochondria are major contributors to endogenous ROS formation. Glycolytic substrates also inhibited Cd(II)/Hg(II)/As(III)-induced ROS formation and confirms that mitochondria are the site of ROS formation. By contrast ROS formation by LD50 concentrations of Cu(II), Ni(II), Co(II) or dichromate [Cr(VI)] were not affected by uncouplers or glycolytic substrates. However they were inhibited by lysosomotropic agents or endogenous inhibitors [in contrast to Hg(II), Cd(II) or As(III)]. Furthermore Cu(II), Ni(II), Co(II) or Cr(VI) accumulated in the lysosomes and the ROS formed caused a loss of lysosomal membrane integrity. The release of lysosomal proteases and phospholipases also contributed to hepatocyte cytotoxicity. ROS formation and cytotoxicity induced by added H2O2 or generated by the intracellular redox cycling of nitrofurantoin was also inhibited by lysosomotropic agents and ferric chelators suggesting that lysosomal Fe(II) contributes to H2O2-induced cytotoxicity. In conclusion, lysosomes are sites of cytotoxic ROS formation with redox transition metals (CuII, CrVI, NiII, CoII) whereas mitochondria are the ROS sites for non-redox or poor redox cycling transition metals (CdII, HgII, AsIII)."
1016576,Harris and  Shi 2003,Signaling by carcinogenic metals and metal-induced reactive oxygen species,"Epidemiological data indicate that exposure to metal and metalloid species, including arsenic(III), chromium(VI), and nickel(II), increases the risk of cancer, particularly of the lung and skin. Alterations in normal signal transduction as a result of exposure to carcinogenic metals, and to metal-catalyzed reactive oxygen species (ROS) formation, appear to play an important role in the etiology of metal-induced carcinogenesis. Signaling components affected by metals include growth factor receptors, G-proteins, MAP kinases, and nuclear transcription factors. This article reviews current literature on the effects of carcinogenic metals and metal-induced ROS on cancer-related signaling pathways. In addition, the mechanisms by which those changes occur, and the role of those changes in carcinogenesis are discussed.","Signaling by carcinogenic metals and metal-induced reactive oxygen species Abs: Epidemiological data indicate that exposure to metal and metalloid species, including arsenic(III), chromium(VI), and nickel(II), increases the risk of cancer, particularly of the lung and skin. Alterations in normal signal transduction as a result of exposure to carcinogenic metals, and to metal-catalyzed reactive oxygen species (ROS) formation, appear to play an important role in the etiology of metal-induced carcinogenesis. Signaling components affected by metals include growth factor receptors, G-proteins, MAP kinases, and nuclear transcription factors. This article reviews current literature on the effects of carcinogenic metals and metal-induced ROS on cancer-related signaling pathways. In addition, the mechanisms by which those changes occur, and the role of those changes in carcinogenesis are discussed."
1016538,Cederkvist et al. 2010,Full-scale removal of arsenate and chromate from water using a limestone and ochreous sludge mixture as a low-cost sorbent material,"The oxyanions arsenate (AsO4(3-)) and chromate (CrO4(2-)) are major freshwater contaminants. Arsenate is a problematic contaminant in drinking water reservoirs, and chromate limits the use of urban stormwater runoff. High-capacity, low-cost, energy-efficient treatment technologies are required for the removal of these toxic anions from freshwater sources. Using a 50-m-long dual porosity filter, with limestone as filtering grains, treating stormwater runoff from Copenhagen, Denmark, we tested if addition of the waste product ochreous sludge can improve the removal of arsenate (As) and chromate (Cr) without compromising the calcite's removal affinity fowards metallic cations. Upon on-site embedding of the ochreous sludge, removal of arsenic and chromium was improved greatly, and copper (Cu) removal remained high. Steady-state effluent concentrations were reduced from 31 to 2 microg As/L, 127 to 1.5 microg Cr/L, and 18 to 9.6 microg Cu/L upon mixing with the ochreous sludge. Limestone-ochreous sludge represents a promising low-cost oxyanion and cation sorbent operating at neutral pH without pH control.","Full-scale removal of arsenate and chromate from water using a limestone and ochreous sludge mixture as a low-cost sorbent material Abs: The oxyanions arsenate (AsO4(3-)) and chromate (CrO4(2-)) are major freshwater contaminants. Arsenate is a problematic contaminant in drinking water reservoirs, and chromate limits the use of urban stormwater runoff. High-capacity, low-cost, energy-efficient treatment technologies are required for the removal of these toxic anions from freshwater sources. Using a 50-m-long dual porosity filter, with limestone as filtering grains, treating stormwater runoff from Copenhagen, Denmark, we tested if addition of the waste product ochreous sludge can improve the removal of arsenate (As) and chromate (Cr) without compromising the calcite's removal affinity fowards metallic cations. Upon on-site embedding of the ochreous sludge, removal of arsenic and chromium was improved greatly, and copper (Cu) removal remained high. Steady-state effluent concentrations were reduced from 31 to 2 microg As/L, 127 to 1.5 microg Cr/L, and 18 to 9.6 microg Cu/L upon mixing with the ochreous sludge. Limestone-ochreous sludge represents a promising low-cost oxyanion and cation sorbent operating at neutral pH without pH control."
1016473,Lee and  Wilkin 2010,Iron hydroxy carbonate formation in zerovalent iron permeable reactive barriers: characterization and evaluation of phase stability,"Predicting the long-term potential of permeable reactive barriers for treating contaminated groundwater relies on understanding the endpoints of biogeochemical reactions between influent groundwater and the reactive medium. Iron hydroxy carbonate (chukanovite) is frequently observed as a secondary mineral precipitate in granular iron PRBs. Mineralogical characterization was carried out using X-ray diffraction, scanning electron microscopy, thermogravimetric analysis, and X-ray absorption spectroscopy on materials collected from three field-based PRBs in the US (East Helena, MT; Elizabeth City, NC; Denver Federal Center, CO). These PRBs were installed to treat a range of contaminants, including chlorinated organics, hexavalent chromium, and arsenic. Results obtained indicate that chukanovite is a prevalent secondary precipitate in the PRBs. Laboratory experiments on high-purity chukanovite separates were carried out to constrain the room-temperature solubility for this mineral. An estimated Gibbs energy of formation (Delta(f)G degrees) for chukanovite is -1174.4 +/- 6 kJ/mol. A mineral stability diagram is consistent with observations from the field. Water chemistry from the three reactive barriers falls inside the predicted stability field for chukanovite, at inorganic carbon concentrations intermediate to the stability fields of siderite and ferrous hydroxide. These new data will aid in developing better predictive models of mineral accumulation in zerovalent iron PRBs.","Iron hydroxy carbonate formation in zerovalent iron permeable reactive barriers: characterization and evaluation of phase stability Abs: Predicting the long-term potential of permeable reactive barriers for treating contaminated groundwater relies on understanding the endpoints of biogeochemical reactions between influent groundwater and the reactive medium. Iron hydroxy carbonate (chukanovite) is frequently observed as a secondary mineral precipitate in granular iron PRBs. Mineralogical characterization was carried out using X-ray diffraction, scanning electron microscopy, thermogravimetric analysis, and X-ray absorption spectroscopy on materials collected from three field-based PRBs in the US (East Helena, MT; Elizabeth City, NC; Denver Federal Center, CO). These PRBs were installed to treat a range of contaminants, including chlorinated organics, hexavalent chromium, and arsenic. Results obtained indicate that chukanovite is a prevalent secondary precipitate in the PRBs. Laboratory experiments on high-purity chukanovite separates were carried out to constrain the room-temperature solubility for this mineral. An estimated Gibbs energy of formation (Delta(f)G degrees) for chukanovite is -1174.4 +/- 6 kJ/mol. A mineral stability diagram is consistent with observations from the field. Water chemistry from the three reactive barriers falls inside the predicted stability field for chukanovite, at inorganic carbon concentrations intermediate to the stability fields of siderite and ferrous hydroxide. These new data will aid in developing better predictive models of mineral accumulation in zerovalent iron PRBs."
1016421,Chowdhury and  Yanful 2010,Arsenic and chromium removal by mixed magnetite-maghemite nanoparticles and the effect of phosphate on removal,"Adsorption of arsenic and chromium by mixed magnetite and maghemite nanoparticles from aqueous solution is a promising technology. In the present batch experimental study, a commercially grade nano-size 'magnetite', later identified in laboratory characterization to be mixed magnetite-maghemite nanoparticles, was used in the uptake of arsenic and chromium from different water samples. The intent was to identify or develop a practical method for future groundwater remediation. The results of the study showed 96-99% arsenic and chromium uptake under controlled pH conditions. The maximum arsenic adsorption occurred at pH 2 with values of 3.69 mg/g for arsenic(III) and 3.71 mg/g for arsenic(V) when the initial concentration was kept at 1.5 mg/L for both arsenic species, while chromium(VI) concentration was 2.4 mg/g at pH 2 with an initial chromium(VI) concentration of 1 mg/L. Thus magnetite-maghemite nanoparticles can readily adsorb arsenic and chromium in an acidic pH range. Redox potential and pH data helped to infer possible dominating species and oxidation states of arsenic and chromium in solution. The results also showed the limitation of arsenic and chromium uptake by the nano-size magnetite-maghemite mixture in the presence of a competing anion such as phosphate. At a fixed adsorbent concentration of 0.4 g/L, arsenic and chromium uptake decreased with increasing phosphate concentration. Nano-size magnetite-maghemite mixed particles adsorbed less than 50% arsenic from synthetic water containing more than 3 mg/L phosphate and 1.2 mg/L of initial arsenic concentration, and less than 50% chromium from synthetic water containing more than 5 mg/L phosphate and 1.0 mg/L of chromium(VI). In natural groundwater containing more than 5 mg/L phosphate and 1.13 mg/L of arsenic, less than 60% arsenic uptake was achieved. In this case, it is anticipated that an optimum design with magnetite-maghemite nanoparticles may achieve high arsenic uptake in field applications.","Arsenic and chromium removal by mixed magnetite-maghemite nanoparticles and the effect of phosphate on removal Abs: Adsorption of arsenic and chromium by mixed magnetite and maghemite nanoparticles from aqueous solution is a promising technology. In the present batch experimental study, a commercially grade nano-size 'magnetite', later identified in laboratory characterization to be mixed magnetite-maghemite nanoparticles, was used in the uptake of arsenic and chromium from different water samples. The intent was to identify or develop a practical method for future groundwater remediation. The results of the study showed 96-99% arsenic and chromium uptake under controlled pH conditions. The maximum arsenic adsorption occurred at pH 2 with values of 3.69 mg/g for arsenic(III) and 3.71 mg/g for arsenic(V) when the initial concentration was kept at 1.5 mg/L for both arsenic species, while chromium(VI) concentration was 2.4 mg/g at pH 2 with an initial chromium(VI) concentration of 1 mg/L. Thus magnetite-maghemite nanoparticles can readily adsorb arsenic and chromium in an acidic pH range. Redox potential and pH data helped to infer possible dominating species and oxidation states of arsenic and chromium in solution. The results also showed the limitation of arsenic and chromium uptake by the nano-size magnetite-maghemite mixture in the presence of a competing anion such as phosphate. At a fixed adsorbent concentration of 0.4 g/L, arsenic and chromium uptake decreased with increasing phosphate concentration. Nano-size magnetite-maghemite mixed particles adsorbed less than 50% arsenic from synthetic water containing more than 3 mg/L phosphate and 1.2 mg/L of initial arsenic concentration, and less than 50% chromium from synthetic water containing more than 5 mg/L phosphate and 1.0 mg/L of chromium(VI). In natural groundwater containing more than 5 mg/L phosphate and 1.13 mg/L of arsenic, less than 60% arsenic uptake was achieved. In this case, it is anticipated that an optimum design with magnetite-maghemite nanoparticles may achieve high arsenic uptake in field applications."
1016045,Tokar et al. 2011,Metal ions in human cancer development,"Metals have been in the environment during the entire evolution of man and the use of metals is key to human civilization. None-the-less, several very toxic species are included in the metallic elements and compounds either widely used by man and/or widely found in the human environment. This includes the five metallic agents considered human carcinogens, namely arsenic and arsenic compounds, beryllium and beryllium compounds, cadmium and cadmium compounds, chromium(VI) compounds, and nickel compounds, all of which are proven carcinogens in laboratory animals as well. There is significant human exposure to these carcinogenic inorganics, either occupationally, through the environment, or both. Inhalation is typical in the workplace while inhalation or ingestion occurs from environmental sources. Human metallic carcinogens frequently cause tumors at the portal of entry and lung cancers are the most common tumor after inhalation. Agent-specific tumors occur as well, like urinary bladder tumors after arsenic exposure, which are due to biokinetics or mechanisms that are specific to arsenic. Even in their simplest elemental form, metals are not inert, and they have biological activity. However, it should be kept in mind that these inorganic carcinogens, when in the atomic form, cannot be broken down into less toxic subunits, and this, in part, is why they are so important as environmental human carcinogens. This chapter focuses on the metallic agents that are known human carcinogens.","Metal ions in human cancer development Abs: Metals have been in the environment during the entire evolution of man and the use of metals is key to human civilization. None-the-less, several very toxic species are included in the metallic elements and compounds either widely used by man and/or widely found in the human environment. This includes the five metallic agents considered human carcinogens, namely arsenic and arsenic compounds, beryllium and beryllium compounds, cadmium and cadmium compounds, chromium(VI) compounds, and nickel compounds, all of which are proven carcinogens in laboratory animals as well. There is significant human exposure to these carcinogenic inorganics, either occupationally, through the environment, or both. Inhalation is typical in the workplace while inhalation or ingestion occurs from environmental sources. Human metallic carcinogens frequently cause tumors at the portal of entry and lung cancers are the most common tumor after inhalation. Agent-specific tumors occur as well, like urinary bladder tumors after arsenic exposure, which are due to biokinetics or mechanisms that are specific to arsenic. Even in their simplest elemental form, metals are not inert, and they have biological activity. However, it should be kept in mind that these inorganic carcinogens, when in the atomic form, cannot be broken down into less toxic subunits, and this, in part, is why they are so important as environmental human carcinogens. This chapter focuses on the metallic agents that are known human carcinogens."
1016019,Muller et al. 2011,An investigation of aircraft worker anemia: medical surveillance interpretation in an aging workforce,"<strong>OBJECTIVE: </strong>To identify exposures possibly contributing to anemia cases among hexavalent chromium medical surveillance program enrollees.<br /><br /><strong>METHODS: </strong>An investigation encompassed metals surveillance programs, extensive workplace sampling and remediation, consultation, evaluation of laboratory accuracy, and follow-up of anemic individuals.<br /><br /><strong>RESULTS: </strong>Workers had underlying medical conditions that affected surveillance results. There was a systemic error in classification based on hematocrit value. The prevalence of anemia in a workforce averaging 52 years old was 16%.<br /><br /><strong>CONCLUSIONS: </strong>Anemia may be more prevalent in middle-aged workers than expected. Modern laboratories generally report a calculated hematocrit value, and using hemoglobin for most classification purposes is preferred. Characteristics of a specific workforce, including age, health, hobbies, and diet, should be taken into account when interpreting medical surveillance program findings. The value of a team approach in addressing occupational health problems was demonstrated.","An investigation of aircraft worker anemia: medical surveillance interpretation in an aging workforce Abs: <strong>OBJECTIVE: </strong>To identify exposures possibly contributing to anemia cases among hexavalent chromium medical surveillance program enrollees.<br /><br /><strong>METHODS: </strong>An investigation encompassed metals surveillance programs, extensive workplace sampling and remediation, consultation, evaluation of laboratory accuracy, and follow-up of anemic individuals.<br /><br /><strong>RESULTS: </strong>Workers had underlying medical conditions that affected surveillance results. There was a systemic error in classification based on hematocrit value. The prevalence of anemia in a workforce averaging 52 years old was 16%.<br /><br /><strong>CONCLUSIONS: </strong>Anemia may be more prevalent in middle-aged workers than expected. Modern laboratories generally report a calculated hematocrit value, and using hemoglobin for most classification purposes is preferred. Characteristics of a specific workforce, including age, health, hobbies, and diet, should be taken into account when interpreting medical surveillance program findings. The value of a team approach in addressing occupational health problems was demonstrated."
1015974,Iqbal and  Bjorklund 2011,Colorimetric analysis of water and sand samples performed on a mobile phone,"Analysis of water and sand samples was done by reflectance measurements using a mobile phone. The phone's screen served as light source and front view camera as detector. Reflected intensities for white, red, green and blue colors were used to do principal component analysis for classification of several compounds and their concentrations in water. Analyses of colored solutions and colorimetric reactions based on widely available chemicals were performed. Classification of iron(III), chromium(VI) and sodium salt of humic acid was observed using reflected intensities from blue and green light for concentrations 2-10mg/l. Addition of complex forming sodium salt of ethylenediaminetetraacidic acid enabled the discrimination of Cu(II) ions in the 2-10mg/l concentration range based on reflection of red light. An alternate method using test strips for copper solutions with the phone as reader also demonstrated a detection limit of 2mg/l. Analysis of As(III) from 25 to 400 ?g/l based on reflection of red light was performed utilizing the bleaching reaction of tincture of iodine containing starch. Enhanced sensitivity to low concentrations of arsenic was obtained by including reflected intensities from white light in the analysis. Model colored sand samples representing discoloration caused by the presence of arsenic in groundwater were analyzed as a complementary method for arsenic detection.","Colorimetric analysis of water and sand samples performed on a mobile phone Abs: Analysis of water and sand samples was done by reflectance measurements using a mobile phone. The phone's screen served as light source and front view camera as detector. Reflected intensities for white, red, green and blue colors were used to do principal component analysis for classification of several compounds and their concentrations in water. Analyses of colored solutions and colorimetric reactions based on widely available chemicals were performed. Classification of iron(III), chromium(VI) and sodium salt of humic acid was observed using reflected intensities from blue and green light for concentrations 2-10mg/l. Addition of complex forming sodium salt of ethylenediaminetetraacidic acid enabled the discrimination of Cu(II) ions in the 2-10mg/l concentration range based on reflection of red light. An alternate method using test strips for copper solutions with the phone as reader also demonstrated a detection limit of 2mg/l. Analysis of As(III) from 25 to 400 ?g/l based on reflection of red light was performed utilizing the bleaching reaction of tincture of iodine containing starch. Enhanced sensitivity to low concentrations of arsenic was obtained by including reflected intensities from white light in the analysis. Model colored sand samples representing discoloration caused by the presence of arsenic in groundwater were analyzed as a complementary method for arsenic detection."
1012845,GBMAFS 1989,Great britain ministry of agriculture fisheries and food food surveillance paper no. 26. migration of substances from food contact materials into food the twenty-sixth report of the steering group on food surveillance progress report of the working party on chemical contaminants from food contact materials for 1984 to 1988,BIOSIS COPYRIGHT: BIOL ABS. RRM BOOK POLYCHLORINATED BIPHENYLS BUTADIENE REGENERATED CELLULOSE FILM PLASTICIZERS COLORING MATERIALS UK,Great britain ministry of agriculture fisheries and food food surveillance paper no. 26. migration of substances from food contact materials into food the twenty-sixth report of the steering group on food surveillance progress report of the working party on chemical contaminants from food contact materials for 1984 to 1988 Abs: BIOSIS COPYRIGHT: BIOL ABS. RRM BOOK POLYCHLORINATED BIPHENYLS BUTADIENE REGENERATED CELLULOSE FILM PLASTICIZERS COLORING MATERIALS UK
1012630,Davenport and  Ball 1979,Observations on the results of specific histochemical techniques and empirical staining methods on several tissue/organ types using a variety of fixing fluids,"Several histotechniques (Harris hematoxylin and alcoholic eosin, Gomori's reticulum method, Verhoeff's elastic stain; Gomori's trichrome, Mallory's aniline blue collagen stain and the Cameron and Steele method) were each used with a number of fixatives (Lavdowsky's chromic acid, Karnovsky's glutaraldehyde/paraformaldehyde, neutral buffered formalin, Lavdowsky's formalinacetic acid-alcohol, Zenker's and Helley's). Lavdowsky's chromic acid fixative provided superior results as compared to the other fixing fluids and its use was critical with respect to the trichrome or connective tissue staining procedures. The Cameron and Steele modification used with Lavdowsky's chromic acid fixative gave the best differentiation of tissue types and was also the most reproducible.","Observations on the results of specific histochemical techniques and empirical staining methods on several tissue/organ types using a variety of fixing fluids Abs: Several histotechniques (Harris hematoxylin and alcoholic eosin, Gomori's reticulum method, Verhoeff's elastic stain; Gomori's trichrome, Mallory's aniline blue collagen stain and the Cameron and Steele method) were each used with a number of fixatives (Lavdowsky's chromic acid, Karnovsky's glutaraldehyde/paraformaldehyde, neutral buffered formalin, Lavdowsky's formalinacetic acid-alcohol, Zenker's and Helley's). Lavdowsky's chromic acid fixative provided superior results as compared to the other fixing fluids and its use was critical with respect to the trichrome or connective tissue staining procedures. The Cameron and Steele modification used with Lavdowsky's chromic acid fixative gave the best differentiation of tissue types and was also the most reproducible."
1010810,David et al. 2011,Transcriptional responses in neonate and adult Daphnia magna in relation to relative susceptibility to genotoxicants,"Little information is available on the responses of lower animals to genotoxic chemicals or on their sensitivity for detecting genotoxic chemicals, especially at different life-stages, despite the established use of the water flea Daphnia magna in ecotoxicity testing. Comet assay methodology was developed and applied to daphnid cells but only limited, non-statistically significant responses to the genotoxicants sodium dichromate (0.2-1 ?M), chrysoidine (0.1-2 ?M), and mixtures of benzo-a-pyrene (BaP) and sodium dichromate were found (from 0.01 ?M BaP &amp; 0.1 ?M sodium dichromate to 0.25 ?M BaP &amp; 0.75 ?M sodium dichromate). Transcriptomic analyses using Agilent D. magna oligonucleotide microarrays were undertaken to assess the effect of a mixture of sodium dichromate and BaP (designed to produce both adducted and oxidised DNA) on gene transcription. Neonates (&lt;24h) and adults (day 7) were exposed for 6h and 24h at two combination concentration levels (0.02 ?M BaP &amp; 0.15 ?M sodium dichromate and 0.1 ?M BaP &amp; 0.75 ?M sodium dichromate). The greatest differences in transcriptional profile occurred between adults and neonates. Subsets of the transcriptional profiles distinguished genotoxicant-exposed animals from controls, both for neonates and adults. Higher transcript levels of DNA repair genes were found in adults and adults also displayed significant induction of DNA repair gene transcripts in response to exposure whereas neonates did not. Transcriptional changes in response to genotoxicant exposure proved more sensitive than measurement of DNA strand breaks by the Comet assay and the extensive differences in transcription between adults and neonates emphasized the importance of life stage in toxicant testing with Daphnia.","Transcriptional responses in neonate and adult Daphnia magna in relation to relative susceptibility to genotoxicants Abs: Little information is available on the responses of lower animals to genotoxic chemicals or on their sensitivity for detecting genotoxic chemicals, especially at different life-stages, despite the established use of the water flea Daphnia magna in ecotoxicity testing. Comet assay methodology was developed and applied to daphnid cells but only limited, non-statistically significant responses to the genotoxicants sodium dichromate (0.2-1 ?M), chrysoidine (0.1-2 ?M), and mixtures of benzo-a-pyrene (BaP) and sodium dichromate were found (from 0.01 ?M BaP &amp; 0.1 ?M sodium dichromate to 0.25 ?M BaP &amp; 0.75 ?M sodium dichromate). Transcriptomic analyses using Agilent D. magna oligonucleotide microarrays were undertaken to assess the effect of a mixture of sodium dichromate and BaP (designed to produce both adducted and oxidised DNA) on gene transcription. Neonates (&lt;24h) and adults (day 7) were exposed for 6h and 24h at two combination concentration levels (0.02 ?M BaP &amp; 0.15 ?M sodium dichromate and 0.1 ?M BaP &amp; 0.75 ?M sodium dichromate). The greatest differences in transcriptional profile occurred between adults and neonates. Subsets of the transcriptional profiles distinguished genotoxicant-exposed animals from controls, both for neonates and adults. Higher transcript levels of DNA repair genes were found in adults and adults also displayed significant induction of DNA repair gene transcripts in response to exposure whereas neonates did not. Transcriptional changes in response to genotoxicant exposure proved more sensitive than measurement of DNA strand breaks by the Comet assay and the extensive differences in transcription between adults and neonates emphasized the importance of life stage in toxicant testing with Daphnia."
1010473,Lijinsky 1990,NON-GENOTOXIC ENVIRONMENTAL CARCINOGENS,BIOSIS COPYRIGHT: BIOL ABS. RRM REVIEW RAT MOUSE HUMAN GUINEA-PIG STOMACH LIVER KIDNEY LUNG TUMORS CARBON TETRACHLORIDE LINDANE DIOXANE POLYCHLORINATED BIPHENYL ETHYLENETHIOUREA 1 1 DIMETHYLHYDRAZINE,NON-GENOTOXIC ENVIRONMENTAL CARCINOGENS Abs: BIOSIS COPYRIGHT: BIOL ABS. RRM REVIEW RAT MOUSE HUMAN GUINEA-PIG STOMACH LIVER KIDNEY LUNG TUMORS CARBON TETRACHLORIDE LINDANE DIOXANE POLYCHLORINATED BIPHENYL ETHYLENETHIOUREA 1 1 DIMETHYLHYDRAZINE
1010470,Walker 1990,EFFECTS OF CHEMICALS ON MICROORGANISMS,BIOSIS COPYRIGHT: BIOL ABS. RRM REVIEW WATER POLLUTION BACTERIAL TOXICITY TESTS ALGAL TOXICITY TESTS FUNGAL TOXICITY TESTS YEAST TOXICITY TESTS QUANTITATIVE STRUCTURE ACTIVITY RELATIONSHIPS,EFFECTS OF CHEMICALS ON MICROORGANISMS Abs: BIOSIS COPYRIGHT: BIOL ABS. RRM REVIEW WATER POLLUTION BACTERIAL TOXICITY TESTS ALGAL TOXICITY TESTS FUNGAL TOXICITY TESTS YEAST TOXICITY TESTS QUANTITATIVE STRUCTURE ACTIVITY RELATIONSHIPS
1010449,Beal 1990,Use of mouse liver tumor data in risk assessments performed by the USA EPA,BIOSIS COPYRIGHT: BIOL ABS. RRM INSECTICIDES BENZENE DERIVATIVES AROMATIC HYDROCARBONS NITROSAMINES,Use of mouse liver tumor data in risk assessments performed by the USA EPA Abs: BIOSIS COPYRIGHT: BIOL ABS. RRM INSECTICIDES BENZENE DERIVATIVES AROMATIC HYDROCARBONS NITROSAMINES
1010405,Batt and  Peterson 1988,RISK ASSESSMENT TECHNIQUES FOR CARCINOGENIC CHEMICALS,BIOSIS COPYRIGHT: BIOL ABS. RRM CHEMICAL INDUSTRY HAZARD PREDICTION INDUSTRIAL POLLUTION,RISK ASSESSMENT TECHNIQUES FOR CARCINOGENIC CHEMICALS Abs: BIOSIS COPYRIGHT: BIOL ABS. RRM CHEMICAL INDUSTRY HAZARD PREDICTION INDUSTRIAL POLLUTION
1010353,H and   1986,HANDLING AND MANAGEMENT OF HAZARDOUS MATERIALS AND WASTE,BIOSIS COPYRIGHT: BIOL ABS. RRM BOOK HUMAN POLYCHLORINATED BIPHENYLS ASBESTOS PESTICIDES ACID RAIN OIL SPILL RADIOACTIVE WASTE RESOURCE CONSERVATION AND RECOVERY ACT TOXIC SUBSTANCES CONTROL ACT,HANDLING AND MANAGEMENT OF HAZARDOUS MATERIALS AND WASTE Abs: BIOSIS COPYRIGHT: BIOL ABS. RRM BOOK HUMAN POLYCHLORINATED BIPHENYLS ASBESTOS PESTICIDES ACID RAIN OIL SPILL RADIOACTIVE WASTE RESOURCE CONSERVATION AND RECOVERY ACT TOXIC SUBSTANCES CONTROL ACT
1010352,Oser 1987,Toxicology then and now,"A review of the history of the evolution of the science of toxicology from the original concepts of Paracelsus through the early development of analytical chemistry and its contributions to the detection of toxic substances in foods and drugs as these have led to modern regulatory rules for public protection is presented. The legal actions taken to protect against adulteration of food prior to the early steps by the U.S. Department of Agriculture that concluded with the passage of the 1906 Food and Drug Act are systematically documented. The history is reviewed of the Food and Drug Administration's role in the use of animal toxicity studies to develop reasonable criteria for safety of foods and drugs for man. Modern concepts of molecular distribution, metabolism, and excretion of substances in the animal body are discussed as these impinge on the so-called “protection index.” The legal and often litigious controversies over the claimed carcinogenicity of chemical substances is documented with comments on the Delaney dilemma and the role of in vitro tests in toxicology. The review concludes with discussion of the hazards of use of stochastic mathematical models to assess carcinogenicity and suggests that the criteria employed in the report of the Scientific Committee of the Food Safety Council are properly structured to give a contemporary evaluation of all the currently available data. References give documentation of events over the past 200 years that explain the present state of toxicology as a discipline.","Toxicology then and now Abs: A review of the history of the evolution of the science of toxicology from the original concepts of Paracelsus through the early development of analytical chemistry and its contributions to the detection of toxic substances in foods and drugs as these have led to modern regulatory rules for public protection is presented. The legal actions taken to protect against adulteration of food prior to the early steps by the U.S. Department of Agriculture that concluded with the passage of the 1906 Food and Drug Act are systematically documented. The history is reviewed of the Food and Drug Administration's role in the use of animal toxicity studies to develop reasonable criteria for safety of foods and drugs for man. Modern concepts of molecular distribution, metabolism, and excretion of substances in the animal body are discussed as these impinge on the so-called “protection index.” The legal and often litigious controversies over the claimed carcinogenicity of chemical substances is documented with comments on the Delaney dilemma and the role of in vitro tests in toxicology. The review concludes with discussion of the hazards of use of stochastic mathematical models to assess carcinogenicity and suggests that the criteria employed in the report of the Scientific Committee of the Food Safety Council are properly structured to give a contemporary evaluation of all the currently available data. References give documentation of events over the past 200 years that explain the present state of toxicology as a discipline."
1010248,Weisburger 1994,GENERAL PRINCIPLES OF CHEMICAL CARCINOGENESIS,BIOSIS COPYRIGHT: BIOL ABS. RRM BOOK CHAPTER LITERATURE REVIEW HUMAN MAMMAL BENZENE POLYCYCLIC AROMATIC HYDROCARBONS NITROSAMINES HYDRAZINES ARSENIC ASBESTOS NICKEL CARCINOGENS NASAL CAVITY LUNG LARYNGEAL BREAST CANCERS,GENERAL PRINCIPLES OF CHEMICAL CARCINOGENESIS Abs: BIOSIS COPYRIGHT: BIOL ABS. RRM BOOK CHAPTER LITERATURE REVIEW HUMAN MAMMAL BENZENE POLYCYCLIC AROMATIC HYDROCARBONS NITROSAMINES HYDRAZINES ARSENIC ASBESTOS NICKEL CARCINOGENS NASAL CAVITY LUNG LARYNGEAL BREAST CANCERS
1010240,Kolb 1993,TERATOGENIC CHEMICALS IN UNDERGRADUATE CHEMISTRY LABORATORIES,BIOSIS COPYRIGHT: BIOL ABS. RRM BOOK CHAPTER HUMAN LABORATORY SAFETY PROCEDURES,TERATOGENIC CHEMICALS IN UNDERGRADUATE CHEMISTRY LABORATORIES Abs: BIOSIS COPYRIGHT: BIOL ABS. RRM BOOK CHAPTER HUMAN LABORATORY SAFETY PROCEDURES
1010169,Legault et al. 1996,Detecting genotoxic activity in industrial effluents using the SOS chromotest microplate assay,"BIOSIS COPYRIGHT: BIOL ABS. The SOS Chromotest, a cost-effective short-term bacterial genotoxicity screening assay, was performed to appraise its capacity for detecting the presence of soluble genotoxic activity in industrial effluent samples (organic and inorganic chemical plants, metallurgical plants, pulp and paper mills, municipal wastewater treatment plants). An optimized methodology, based on criteria taking into account beta-galactosidase activity (the indicator of SOS gene induction), alkaline phosphatase activity (the indicator of cytotoxicity), and two genotoxicity measurement end points (minimum genotoxic concentration and maximum induction factor), was employed to generate reliable results that overcame the potential interferences inherent to complex wastewaters. Of 48 effluent samples tested, 37 (77%) elicited a significant induction of the Escherichia coli PQ37 SOS response. Effluents from inorganic chemical plants and pulp and paper mills displayed the most potent responses, with an","Detecting genotoxic activity in industrial effluents using the SOS chromotest microplate assay Abs: BIOSIS COPYRIGHT: BIOL ABS. The SOS Chromotest, a cost-effective short-term bacterial genotoxicity screening assay, was performed to appraise its capacity for detecting the presence of soluble genotoxic activity in industrial effluent samples (organic and inorganic chemical plants, metallurgical plants, pulp and paper mills, municipal wastewater treatment plants). An optimized methodology, based on criteria taking into account beta-galactosidase activity (the indicator of SOS gene induction), alkaline phosphatase activity (the indicator of cytotoxicity), and two genotoxicity measurement end points (minimum genotoxic concentration and maximum induction factor), was employed to generate reliable results that overcame the potential interferences inherent to complex wastewaters. Of 48 effluent samples tested, 37 (77%) elicited a significant induction of the Escherichia coli PQ37 SOS response. Effluents from inorganic chemical plants and pulp and paper mills displayed the most potent responses, with an"
1010133,Meijers J et al. 1997,The predictive value of animal data in human cancer risk assessment,"BIOSIS COPYRIGHT: BIOL ABS. Carcinogenic effects of chemicals can be investigated in animal experiments and epidemiological studies of exposed humans, mostly in the workplace. In this article epidemiologic evidence is compared with the animal data for 35 chemicals. Risk calculations are compared for 22 chemicals. The chemicals showing no or unclear carcinogenic effects in humans were more likely to show toxic side effects in the animal studies, indicating that the test concentrations were above the maximum tolerated dose. In addition, the animal experiments with these chemicals more often showed neoplastic effects on multiple sites than chemicals for which clear positive epidemiological studies are available. These findings may explain the existence of discrepancies between the outcomes of animal testing and human studies. They suggest that carcinogenic effects in multiple organs in animals could be seen as ultimate manifestations of the side effects of the testing method and that they have limite","The predictive value of animal data in human cancer risk assessment Abs: BIOSIS COPYRIGHT: BIOL ABS. Carcinogenic effects of chemicals can be investigated in animal experiments and epidemiological studies of exposed humans, mostly in the workplace. In this article epidemiologic evidence is compared with the animal data for 35 chemicals. Risk calculations are compared for 22 chemicals. The chemicals showing no or unclear carcinogenic effects in humans were more likely to show toxic side effects in the animal studies, indicating that the test concentrations were above the maximum tolerated dose. In addition, the animal experiments with these chemicals more often showed neoplastic effects on multiple sites than chemicals for which clear positive epidemiological studies are available. These findings may explain the existence of discrepancies between the outcomes of animal testing and human studies. They suggest that carcinogenic effects in multiple organs in animals could be seen as ultimate manifestations of the side effects of the testing method and that they have limite"
1010112,Winder and  Gonzalez-Calderon 1998,USE OF EC CRITERIA FOR DETERMINING HEALTH AND ENVIRONMENTAL HAZARDS FOR CLASSIFICATION OF CHEMICALS FOR ENVIRONMENTAL RISK,BIOSIS COPYRIGHT: BIOL ABS. RRM JOURNAL ARTICLE RESEARCH AUSTRALIAN NATIONAL ENVIRONMENT PROTECTION COUNCIL HAZARDOUS SUBSTANCES EC CRITERIA EUROPEAN COMMUNITY CRITERIA HEALTH AND ENVIRONMENTAL HAZARDS CHEMICAL CLASSIFICATION ENVIRONMENTAL RISK NATIONAL POLLUTANT INVENTORY TOXICOLOGY GOVERNMENT AND LAW POLLUTION AUSTRALIA GOVERNMENT AGENCY,USE OF EC CRITERIA FOR DETERMINING HEALTH AND ENVIRONMENTAL HAZARDS FOR CLASSIFICATION OF CHEMICALS FOR ENVIRONMENTAL RISK Abs: BIOSIS COPYRIGHT: BIOL ABS. RRM JOURNAL ARTICLE RESEARCH AUSTRALIAN NATIONAL ENVIRONMENT PROTECTION COUNCIL HAZARDOUS SUBSTANCES EC CRITERIA EUROPEAN COMMUNITY CRITERIA HEALTH AND ENVIRONMENTAL HAZARDS CHEMICAL CLASSIFICATION ENVIRONMENTAL RISK NATIONAL POLLUTANT INVENTORY TOXICOLOGY GOVERNMENT AND LAW POLLUTION AUSTRALIA GOVERNMENT AGENCY
1010073,Henschler 1987,Risk assessment and evaluation of chemical carcinogens —Present and future strategies,BIOSIS COPYRIGHT: BIOL ABS. RRM HUMAN ANIMAL OCCUPATIONAL CANCER DELANEY CLAUSE NATIONAL CANCER INSTITUTE NATIONAL TOXICOLOGY PROGRAM,Risk assessment and evaluation of chemical carcinogens —Present and future strategies Abs: BIOSIS COPYRIGHT: BIOL ABS. RRM HUMAN ANIMAL OCCUPATIONAL CANCER DELANEY CLAUSE NATIONAL CANCER INSTITUTE NATIONAL TOXICOLOGY PROGRAM
1010060,Bailey et al. 1985,TIME-TOXICITY RELATIONSHIPS IN SHORT-TERM STATIC DYNAMIC AND PLUG-FLOW BIOASSAYS,BIOSIS COPYRIGHT: BIOL ABS. RRM BLUEGILL ACRYLONITRILE AMMONIA CHLOROBENZENE CHROMIC-ACID COPPER SULFATE XYLENE 2 ETHOXYETHYLACETATE METHYL METHACRYLATE SODIUM HYDROXIDE SULFURIC-ACID LC-50 WATER POLLUTION,TIME-TOXICITY RELATIONSHIPS IN SHORT-TERM STATIC DYNAMIC AND PLUG-FLOW BIOASSAYS Abs: BIOSIS COPYRIGHT: BIOL ABS. RRM BLUEGILL ACRYLONITRILE AMMONIA CHLOROBENZENE CHROMIC-ACID COPPER SULFATE XYLENE 2 ETHOXYETHYLACETATE METHYL METHACRYLATE SODIUM HYDROXIDE SULFURIC-ACID LC-50 WATER POLLUTION
1010009,González and  Agudo 1999,Occupational cancer in Spain,"The knowledge of specific problems of occupational cancer in Spain is scarce. The environment of the workplace has improved over the last few years after a long period distinguished by bad working conditions, incomplete legislation, and insufficient safety measures and control. It has been estimated that 3,083,479 workers (25.4% of employees) were exposed to carcinogens. The most common occupational exposures to carcinogenic agents were solar radiation, environmental tobacco smoke, silica, and w her European countries, the incidence of lung cancer and leukemia in Spain are one of the lowest, but it is rapidly increasing. The incidence of urinary bladder and larynx cancer, on the contrary, are one of the highest. Few studies on occupational cancer have been conducted in Spain. The main problems are the availability of death certificates and the quality of the information on occupation in mortality of statistics. It is necessary to improve methods of assessment of exposure","Occupational cancer in Spain Abs: The knowledge of specific problems of occupational cancer in Spain is scarce. The environment of the workplace has improved over the last few years after a long period distinguished by bad working conditions, incomplete legislation, and insufficient safety measures and control. It has been estimated that 3,083,479 workers (25.4% of employees) were exposed to carcinogens. The most common occupational exposures to carcinogenic agents were solar radiation, environmental tobacco smoke, silica, and w her European countries, the incidence of lung cancer and leukemia in Spain are one of the lowest, but it is rapidly increasing. The incidence of urinary bladder and larynx cancer, on the contrary, are one of the highest. Few studies on occupational cancer have been conducted in Spain. The main problems are the availability of death certificates and the quality of the information on occupation in mortality of statistics. It is necessary to improve methods of assessment of exposure"
1009821,Halebsky 1980,OCEAN INCINERATION OF TOXIC CHEMICAL WASTES,HEEP COPYRIGHT: BIOL ABS.,OCEAN INCINERATION OF TOXIC CHEMICAL WASTES Abs: HEEP COPYRIGHT: BIOL ABS.
1009583,NIOSH 1989,NIOSH manual of analytical methods: Third edition: Third supplement,"This supplement contained 34 methods of analysis for 69 toxic chemical compounds and served as an update to the NIOSH manual of analytical methods. Methods were selected on the basis of their use, input from the clients and NIOSH chemists on need for change, and the health implications of the compounds. Methods were included for acetaldehyde (75070), acetic-acid (64197), acrylonitrile (107131), aldehydes, aliphatic amines, aminoethanol compounds, asbestos (1332214) bulk and fibers, 1-butanethiol (109795), chlordane (57749), hexavalent chromium compounds, cyanuric-acid, (108805), ethyleneamines, endrin (72208), fibers, formaldehyde (50000), furfuryl-alcohol (98000), glutaraldehyde (111308), hydrogen-cyanide (74908), isocyanates, ketones, mercury (7439976), methyl-methacrylate (80626), nitrosamines, pentachlorophenol (87865), quartz (14808607) in coal mine dust, ribavirin (36791045), respirable crystalline silica, sulfur-dioxide (7446095), toluene diamines, and valeraldehyde (110623).","NIOSH manual of analytical methods: Third edition: Third supplement Abs: This supplement contained 34 methods of analysis for 69 toxic chemical compounds and served as an update to the NIOSH manual of analytical methods. Methods were selected on the basis of their use, input from the clients and NIOSH chemists on need for change, and the health implications of the compounds. Methods were included for acetaldehyde (75070), acetic-acid (64197), acrylonitrile (107131), aldehydes, aliphatic amines, aminoethanol compounds, asbestos (1332214) bulk and fibers, 1-butanethiol (109795), chlordane (57749), hexavalent chromium compounds, cyanuric-acid, (108805), ethyleneamines, endrin (72208), fibers, formaldehyde (50000), furfuryl-alcohol (98000), glutaraldehyde (111308), hydrogen-cyanide (74908), isocyanates, ketones, mercury (7439976), methyl-methacrylate (80626), nitrosamines, pentachlorophenol (87865), quartz (14808607) in coal mine dust, ribavirin (36791045), respirable crystalline silica, sulfur-dioxide (7446095), toluene diamines, and valeraldehyde (110623)."
1009565,Alavanja et al. 1990,Risk assessment for carcinogens: A comparison of approaches of the ACGIH and the EPA,The relative carcinogenic potency of 16 chemicals evaluated by both the U.S. Environmental Protection Agency (EPA) and the Chemical Substances Threshold Limit Values (CS-TLV) Committee of the American Conference of Governmental Industrial Hygienists (ACGIH) were compared. The estimated cancer risk resulting from occupational exposure to the threshold limit values (TLVs) were also computed using dose-response curves developed as a part of EPA quantitative risk assessments. Substantial agreement between the EPA and the CS-TLV Committee was found when the relative potency of these carcinogens was compared. Use of EPA's risk model to estimate lifetime cancer risk from occupational exposure at the TLV levels often resulted in high cancer risk estimates. The approaches used to assess cancer risk by both groups is described and a suggestion is made for incorporating existing quantitative risk assessments into the TLV evaluation procedure.,Risk assessment for carcinogens: A comparison of approaches of the ACGIH and the EPA Abs: The relative carcinogenic potency of 16 chemicals evaluated by both the U.S. Environmental Protection Agency (EPA) and the Chemical Substances Threshold Limit Values (CS-TLV) Committee of the American Conference of Governmental Industrial Hygienists (ACGIH) were compared. The estimated cancer risk resulting from occupational exposure to the threshold limit values (TLVs) were also computed using dose-response curves developed as a part of EPA quantitative risk assessments. Substantial agreement between the EPA and the CS-TLV Committee was found when the relative potency of these carcinogens was compared. Use of EPA's risk model to estimate lifetime cancer risk from occupational exposure at the TLV levels often resulted in high cancer risk estimates. The approaches used to assess cancer risk by both groups is described and a suggestion is made for incorporating existing quantitative risk assessments into the TLV evaluation procedure.
1009557,Anttila et al. 1993,Carcinogenic Chemicals in the Occupational Environment,"A study of exposures of Finnish workers to carcinogens was conducted. Data contained in registries of the Finnish Institute of Occupational Health (FIOH) were reviewed to determine the number of workers exposed to suspected carcinogens in their workplaces in 1989 and to identify specific carcinogen exposures that occurred between 1980 and 1985. Data on exposures to lead (7439921), styrene (100425), tetrachloroethylene (127184), and trichloroethylene (79016) obtained by FIOH surveys between 1973 and 1987 were examined to assess possible trends in exposure. A total of 17,118 workers in 1899 workplaces were registered as being exposed to carcinogens in 1989. Jobs most frequently listed as having carcinogen exposures were: engine repairman 17% of the total, welder 14%, metal plater 8%, engine installer 7%, and miscellaneous which accounted for 44% of the total jobs listed. The most common carcinogen exposures associated with these jobs were hexavalent chromium (Cr+6) compounds, nickel compounds, asbestos (1332214), and benzene (71432). At least 10,000 workers were estimated to be exposed annually to silica (14808607) and wood dust, tobacco smoke, lead, Cr+6 and nickel compounds, mineral fibers, asbestos, polycyclic aromatic hydrocarbons, and formaldehyde (50000). About 1000 workers were estimated to be exposed annually to acrylonitrile (107131), carbon-tetrachloride (56235), dioxane (123911), other organic solvents, polychlorinated biphenyls, and thiourea (62566). Occupational lead exposures decreased over time. Exposures to styrene and trichloroethylene decreased only slightly. Tetrachloroethylene exposures seemed to have remained constant. The authors conclude that on the basis of the FIOH data, more than 100,000 Finnish workers are probably exposed to carcinogens in their workplaces. Silica, wood dust, tobacco smoke, and lead are the most frequently encountered exposures.","Carcinogenic Chemicals in the Occupational Environment Abs: A study of exposures of Finnish workers to carcinogens was conducted. Data contained in registries of the Finnish Institute of Occupational Health (FIOH) were reviewed to determine the number of workers exposed to suspected carcinogens in their workplaces in 1989 and to identify specific carcinogen exposures that occurred between 1980 and 1985. Data on exposures to lead (7439921), styrene (100425), tetrachloroethylene (127184), and trichloroethylene (79016) obtained by FIOH surveys between 1973 and 1987 were examined to assess possible trends in exposure. A total of 17,118 workers in 1899 workplaces were registered as being exposed to carcinogens in 1989. Jobs most frequently listed as having carcinogen exposures were: engine repairman 17% of the total, welder 14%, metal plater 8%, engine installer 7%, and miscellaneous which accounted for 44% of the total jobs listed. The most common carcinogen exposures associated with these jobs were hexavalent chromium (Cr+6) compounds, nickel compounds, asbestos (1332214), and benzene (71432). At least 10,000 workers were estimated to be exposed annually to silica (14808607) and wood dust, tobacco smoke, lead, Cr+6 and nickel compounds, mineral fibers, asbestos, polycyclic aromatic hydrocarbons, and formaldehyde (50000). About 1000 workers were estimated to be exposed annually to acrylonitrile (107131), carbon-tetrachloride (56235), dioxane (123911), other organic solvents, polychlorinated biphenyls, and thiourea (62566). Occupational lead exposures decreased over time. Exposures to styrene and trichloroethylene decreased only slightly. Tetrachloroethylene exposures seemed to have remained constant. The authors conclude that on the basis of the FIOH data, more than 100,000 Finnish workers are probably exposed to carcinogens in their workplaces. Silica, wood dust, tobacco smoke, and lead are the most frequently encountered exposures."
1009513,Leduc et al. 1982,The effects of cyanides on aquatic organisms with emphasis upon freshwater fishes,"Free cyanide: Free cyanide, composed of the equilibrium summation of molecular HCN and the cyanide ion, is considered the primary toxic agent in the aquatic environment. In natural waters with a pH of 8.5 or lower, most of the free cyanide is in the form of molecular HCN. Simple cyanide: Simple cyanides, represented by the formula M(CN)X, exhibit a diverse range of aqueous solubilities and degrees of ionization. Soluble simple cyanides, notably some alkali cyanides, readily release cyanide ion in solution; the cyanide ion may then enter into equilibrium with molecular HCN. Complex cyanide: Transition metals of the ""d"" block and their near neighbours combine with cyanide ions to produce various complex cyanides, depending upon such factors as solution strength and stoichiometric proportions. Several metallocyanide compounds dissociate in aqueous solution, thereby generating complex cyanide ions. These ions may, depending upon conditions, further dissociate yielding cyanide ions. In general, complex ions are more stable than the parent metallocyanide and their subsequent dissociation may be relatively small. However, the extent to which a complex cyanide dissociates is of little importance in environmental systems; instead, the important factor is the rate at which cyanide bound in the complex exchanges with the cyanide ion (i.e. free cyanide) in solution. Toxicity of complex cyanides is usually related to the capacity of complex cyanide ions to release cyanide ions in solution, which then enter into an equilibrium with molecular HCN. Relatively small fluctuations in pH may have a significant effect upon toxicity, as has been demonstrated for the tetracyanonickelate II complex. Organocyanides (nitriles): Organic compounds containing the -CN group can be termed cyanides or nitriles, depending upon the nomenclature used. From the point of view of free cyanide toxicity, many organocyanide compounds are considered relatively innocuous in aqueous systems because of their low chemical reactivity and biodegradability. Most degradative mechanisms involve a cleavage of the CN bond and hence the cyanide ion is not generated. It should be kept in mind, however, that some nitriles are toxic per se, although such toxicity is not attributable to release of the cyanide ion. Cyanohydrins (R2C(OH)CN) and cyanogenic glycosides (R1R2C(OR3)CN), are special classes of nitriles in that under appropriate conditions, they will release cyanide ions (i.e. free cyanide) in solution. Other related compounds: Cyanides (mainly free and simple) may be converted to cyanates (compounds containing the group -OCN) during waste treatment. Aqueous solutions of cyanate hydrolyze to ammonia and bicarbonate. In the presence of reduced sulfur compounds, particularly polysulfide sulfur, cyanides are converted to thiocyanates (compounds containing the group -SCN). Thiocyanates are relatively more stable in aqueous solution than cyanates and may form complexes with a number of elements. Analytical methodology: Free cyanide can be selectively determined by variations of gas stripping and aqueous diffusion techniques. Analysis of total cyanides can be accomplished by acid distillation with detection by selective ion electrode, titration or colorimetry. Pretreatment and modifications to the acid distillation step are commonly employed to ascertain some fractions of total cyanide. Such modifications include cyanide amenable to chlorination, weak acid dissociable cyanide and simple versus complex cyanide. Qualitative differences existing between the measured fractions may have some bearing upon their toxicity. A comparison of different analytical methods used to measure various cyanide species is presented in Table 2-4. Environmental dynamics: Very little reliable information is available on sources, levels, fates and environmental dynamics of cyanide compounds in dilute aqueous systems. Sources: The presence of cyanides in natural waters is attributed to both natural processes and man-made activities. Although molecular HCN may be produced naturally by microorgani ms as well as from the cyanogenic degradation of glycosides, the environmental significance related to such sources has not been assessed. Compounds containing the cyanide group also enter the aquatic environment via point sources associated with certain industrial activities as well as nonpoint sources associated with the application of materials containing cyanide compounds. Detectable levels of cyanide in the environment (usually measured as some form of the total cyanide) are considered to result from improper management practices such as improper storage, handling and disposal of wastes. The pyrolysis of some cyanide-containing materials leads to the production of hydrogen cyanide; the atmospheric transport, transformation and possible entry into the aquatic environment have not been examined. Levels: The limited data that are available on the distribution of cyanide compounds in the aquatic environment have usually been obtained using techniques to measure only total cyanide, irrespective of the chemical species that may actually be present in such samples. Fragmentary information indicates that total cyanide concentrations in rural areas are related to the size of the watershed and seasonal run-off. Levels of total cyanide are found to be significantly lower in rural and wilderness waters than in waters of industrial origin. Fate in the aquatic environment: Very little information has appeared in the literature pertaining to the fate of cyanide compounds in natural waters. Depending upon the cyanide species in question and physicochemical conditions, such interactions as oxidation-reduction, volatilization, hydrolysis, photolysis, dissociation, photoaquation, biodegradation, biogenesis and precipitation-dissolution may be important. With few exceptions, studies have been conducted only under conditions which simulate highly concentrated process water or effluents. Dynamic interactions in an environmental context are virtually unexplored. Hydrogen cyanide is volatile, having a vapor pressure of 53.1 kPa at 10.2?C and will be in equilibrium with atmospheric HCN approximately according to Henry's Law. Volatilization is expected to be a significant means of free cyanide (and in some cases simple cyanide) removal from concentrated effluents: however, it may be a rate-determining step in dilute aqueous systems. Data on chemical oxidation and adsorption to solids of molecular HCN in dilute aqueous systems are unavailable. Numerous microorganisms have been identified that can degrade molecular HCN. Microbial degradation has been employed as a biological treatment method; however, acclimation to low levels of cyanides are required in order for the mixed cultures to be effective. The relationship between biological synthesis and degradation of molecular HCN, and its environmental significance, has not been investigated. If conditions in dilute aqueous systems are such that complex cyanide ions release cyanide ions, which will then enter into equilibrium with molecular HCN, the removal mechanisms indicated above will apply. Numerous metallocyanide complex ions are relatively stable in aqueous solution in the absence of ultraviolet and visible light. However, under certain conditions, photodecomposition, with subsequent release of cyanide ions, will occur. The significance of biological degradation, adsorption to solids and other relevant processes in dilute aqueous solution has not been assessed. It is postulated that some of the various mechanisms involved in the removal of cyanide compounds from the water column may result in localized pools or sinks of such material that, upon changing conditions, may release free cyanide or other cyanide-containing material back into the water column. Toxicology: Free cyanide: The acute mode of action of HCN is limited to binding those porphyrins that contain iron III, such as cytochrome oxidase, hydroperoxidases, and methemoglobin. At lethal levels, cyanide is therefore primarily a respiratory poison and one of the most rapidly effective toxicants known. Concentrations in the range of 3 -150 ug.L-1 HCN may be acutely toxic and include the lethal thresholds and median tolerance concentrations for most cold- and warm-water fishes. The acute toxicity of HCN can be influenced by several modifying factors; however, temperature appears to be most significant. The influence of temperature is related to the HCN concentrations present. At high, rapidly lethal concentrations, cyanide is more toxic at elevated temperatures whereas at relatively low, slowly lethal levels the opposite is true. At the chronic level of exposure, metabolic processes other than biological oxidation may be responsible for detrimental effects observed at HCN concentrations as low as 5 ug.L-1. Various responses of ecological significance have been measured. Reproductive impairment has been demonstrated under continuous chronic exposure to HCN at concentrations as low as 4 ug.L-1. All such tests have revealed significant detrimental effects upon reproductive processes at approximately 10 ug.L-1. Fertilized eggs are relatively resistant to free cyanide prior to blastulation, however, teratogenesis and mortality following blastulation, in addition to mortality of newly hatched larvae, have occurred at concentrations of approximately 60-100 ug.L-1. The growth of juvenile fish may be severely affected during chronic exposures to 10 ug.L-1, although transient growth enhancement has been demonstrated. Tolerance (e.g. levels affecting growth) may change with body size. Chronic exposure to 10 ug.L-1 HCN has been shown to elevate resting metabolic rate above basal levels. However, this oxidative stimulation in relatively inactive fish remains unexplained. The active swimming ability required for migration, feeding, and escape from predators is severely affected by free cyanide. An experimental situation simulating anadromous migration revealed osmoregulatory disturbances at 10 ug.L-1 HCN in fresh water, following a period of several days in salt water. Other related compounds: Few detailed toxicity tests have been conducted into the effects of simple cyanide-containing compounds upon aquatic organisms. Cyanates are believed to be relatively nontoxic although the 96-h LC50 for mercuric thiocyanate was determined to be 120 ug.L-1 for a marine invertebrate and 180 ug.L-1 for a freshwater fish. Cyanogen chloride is toxic to fish at 40 ug.L-1. Metallo- and organocyanides: The toxicity of metallocyanides may in part be related to molecular structures, as discussed in Section 2.5 of the text. An inherent toxicity is associated with tetracyanonickelate II, dicyanoargentate I, and dicyanocuprate I. The nickel complex, which may have an accumulative mode of action, has been estimated as lethally toxic to fish at 1.0 mg.L-1 as total cyanide. The toxic silver and copper complexes may not be significant in the environment because of their removal by wastewater treatment and their rapid dissociation upon dilution of effluents. Iron cyanide complexes are extremely stable in the absence of ultraviolet or visible light and are essentially nontoxic. However, they can undergo photolysis under certain circumstances and release toxic levels of free cyanide. The inherent toxicity associated with cobalt and mercury complexes (other than mercuric thiocyanate) has not been investigated. Toxicity of cyano complexes of chromium, cadmium, zinc, and lead has not been demonstrated; however, solutions of these complexes may produce toxic levels of free cyanide. Within the organocyanides is a group of cyanohydrins (e.g. lactonitrile) which may produce sufficient HCN via hydrolysis to elicit toxic responses in short-term exposure situations. Other nitriles are less toxic in acute conditions. For example, the 100-d LC50 for rainbow trout was estimated as 1.6 mg.L-1 as acrylonitrile. Chronic toxicity has not been adequately investigated. Multiple toxicity: Binary mixtures of free cyanide plus hexavalent chromium, zinc, or ammonia resulted in more fish lethalities than predicted by either response addition or concentration addition models. However, at sublethal levels, only the NH3-HC binary mixture had an interactive effect whereas Cr-HCN and Zn-HCN combinations demonstrated independent modes of action. Binary mixtures of arsenic plus free cyanide may elicit effects at sublethal levels which are predictable according to a response addition model.","The effects of cyanides on aquatic organisms with emphasis upon freshwater fishes Abs: Free cyanide: Free cyanide, composed of the equilibrium summation of molecular HCN and the cyanide ion, is considered the primary toxic agent in the aquatic environment. In natural waters with a pH of 8.5 or lower, most of the free cyanide is in the form of molecular HCN. Simple cyanide: Simple cyanides, represented by the formula M(CN)X, exhibit a diverse range of aqueous solubilities and degrees of ionization. Soluble simple cyanides, notably some alkali cyanides, readily release cyanide ion in solution; the cyanide ion may then enter into equilibrium with molecular HCN. Complex cyanide: Transition metals of the ""d"" block and their near neighbours combine with cyanide ions to produce various complex cyanides, depending upon such factors as solution strength and stoichiometric proportions. Several metallocyanide compounds dissociate in aqueous solution, thereby generating complex cyanide ions. These ions may, depending upon conditions, further dissociate yielding cyanide ions. In general, complex ions are more stable than the parent metallocyanide and their subsequent dissociation may be relatively small. However, the extent to which a complex cyanide dissociates is of little importance in environmental systems; instead, the important factor is the rate at which cyanide bound in the complex exchanges with the cyanide ion (i.e. free cyanide) in solution. Toxicity of complex cyanides is usually related to the capacity of complex cyanide ions to release cyanide ions in solution, which then enter into an equilibrium with molecular HCN. Relatively small fluctuations in pH may have a significant effect upon toxicity, as has been demonstrated for the tetracyanonickelate II complex. Organocyanides (nitriles): Organic compounds containing the -CN group can be termed cyanides or nitriles, depending upon the nomenclature used. From the point of view of free cyanide toxicity, many organocyanide compounds are considered relatively innocuous in aqueous systems because of their low chemical reactivity and biodegradability. Most degradative mechanisms involve a cleavage of the CN bond and hence the cyanide ion is not generated. It should be kept in mind, however, that some nitriles are toxic per se, although such toxicity is not attributable to release of the cyanide ion. Cyanohydrins (R2C(OH)CN) and cyanogenic glycosides (R1R2C(OR3)CN), are special classes of nitriles in that under appropriate conditions, they will release cyanide ions (i.e. free cyanide) in solution. Other related compounds: Cyanides (mainly free and simple) may be converted to cyanates (compounds containing the group -OCN) during waste treatment. Aqueous solutions of cyanate hydrolyze to ammonia and bicarbonate. In the presence of reduced sulfur compounds, particularly polysulfide sulfur, cyanides are converted to thiocyanates (compounds containing the group -SCN). Thiocyanates are relatively more stable in aqueous solution than cyanates and may form complexes with a number of elements. Analytical methodology: Free cyanide can be selectively determined by variations of gas stripping and aqueous diffusion techniques. Analysis of total cyanides can be accomplished by acid distillation with detection by selective ion electrode, titration or colorimetry. Pretreatment and modifications to the acid distillation step are commonly employed to ascertain some fractions of total cyanide. Such modifications include cyanide amenable to chlorination, weak acid dissociable cyanide and simple versus complex cyanide. Qualitative differences existing between the measured fractions may have some bearing upon their toxicity. A comparison of different analytical methods used to measure various cyanide species is presented in Table 2-4. Environmental dynamics: Very little reliable information is available on sources, levels, fates and environmental dynamics of cyanide compounds in dilute aqueous systems. Sources: The presence of cyanides in natural waters is attributed to both natural processes and man-made activities. Although molecular HCN may be produced naturally by microorgani ms as well as from the cyanogenic degradation of glycosides, the environmental significance related to such sources has not been assessed. Compounds containing the cyanide group also enter the aquatic environment via point sources associated with certain industrial activities as well as nonpoint sources associated with the application of materials containing cyanide compounds. Detectable levels of cyanide in the environment (usually measured as some form of the total cyanide) are considered to result from improper management practices such as improper storage, handling and disposal of wastes. The pyrolysis of some cyanide-containing materials leads to the production of hydrogen cyanide; the atmospheric transport, transformation and possible entry into the aquatic environment have not been examined. Levels: The limited data that are available on the distribution of cyanide compounds in the aquatic environment have usually been obtained using techniques to measure only total cyanide, irrespective of the chemical species that may actually be present in such samples. Fragmentary information indicates that total cyanide concentrations in rural areas are related to the size of the watershed and seasonal run-off. Levels of total cyanide are found to be significantly lower in rural and wilderness waters than in waters of industrial origin. Fate in the aquatic environment: Very little information has appeared in the literature pertaining to the fate of cyanide compounds in natural waters. Depending upon the cyanide species in question and physicochemical conditions, such interactions as oxidation-reduction, volatilization, hydrolysis, photolysis, dissociation, photoaquation, biodegradation, biogenesis and precipitation-dissolution may be important. With few exceptions, studies have been conducted only under conditions which simulate highly concentrated process water or effluents. Dynamic interactions in an environmental context are virtually unexplored. Hydrogen cyanide is volatile, having a vapor pressure of 53.1 kPa at 10.2?C and will be in equilibrium with atmospheric HCN approximately according to Henry's Law. Volatilization is expected to be a significant means of free cyanide (and in some cases simple cyanide) removal from concentrated effluents: however, it may be a rate-determining step in dilute aqueous systems. Data on chemical oxidation and adsorption to solids of molecular HCN in dilute aqueous systems are unavailable. Numerous microorganisms have been identified that can degrade molecular HCN. Microbial degradation has been employed as a biological treatment method; however, acclimation to low levels of cyanides are required in order for the mixed cultures to be effective. The relationship between biological synthesis and degradation of molecular HCN, and its environmental significance, has not been investigated. If conditions in dilute aqueous systems are such that complex cyanide ions release cyanide ions, which will then enter into equilibrium with molecular HCN, the removal mechanisms indicated above will apply. Numerous metallocyanide complex ions are relatively stable in aqueous solution in the absence of ultraviolet and visible light. However, under certain conditions, photodecomposition, with subsequent release of cyanide ions, will occur. The significance of biological degradation, adsorption to solids and other relevant processes in dilute aqueous solution has not been assessed. It is postulated that some of the various mechanisms involved in the removal of cyanide compounds from the water column may result in localized pools or sinks of such material that, upon changing conditions, may release free cyanide or other cyanide-containing material back into the water column. Toxicology: Free cyanide: The acute mode of action of HCN is limited to binding those porphyrins that contain iron III, such as cytochrome oxidase, hydroperoxidases, and methemoglobin. At lethal levels, cyanide is therefore primarily a respiratory poison and one of the most rapidly effective toxicants known. Concentrations in the range of 3 -150 ug.L-1 HCN may be acutely toxic and include the lethal thresholds and median tolerance concentrations for most cold- and warm-water fishes. The acute toxicity of HCN can be influenced by several modifying factors; however, temperature appears to be most significant. The influence of temperature is related to the HCN concentrations present. At high, rapidly lethal concentrations, cyanide is more toxic at elevated temperatures whereas at relatively low, slowly lethal levels the opposite is true. At the chronic level of exposure, metabolic processes other than biological oxidation may be responsible for detrimental effects observed at HCN concentrations as low as 5 ug.L-1. Various responses of ecological significance have been measured. Reproductive impairment has been demonstrated under continuous chronic exposure to HCN at concentrations as low as 4 ug.L-1. All such tests have revealed significant detrimental effects upon reproductive processes at approximately 10 ug.L-1. Fertilized eggs are relatively resistant to free cyanide prior to blastulation, however, teratogenesis and mortality following blastulation, in addition to mortality of newly hatched larvae, have occurred at concentrations of approximately 60-100 ug.L-1. The growth of juvenile fish may be severely affected during chronic exposures to 10 ug.L-1, although transient growth enhancement has been demonstrated. Tolerance (e.g. levels affecting growth) may change with body size. Chronic exposure to 10 ug.L-1 HCN has been shown to elevate resting metabolic rate above basal levels. However, this oxidative stimulation in relatively inactive fish remains unexplained. The active swimming ability required for migration, feeding, and escape from predators is severely affected by free cyanide. An experimental situation simulating anadromous migration revealed osmoregulatory disturbances at 10 ug.L-1 HCN in fresh water, following a period of several days in salt water. Other related compounds: Few detailed toxicity tests have been conducted into the effects of simple cyanide-containing compounds upon aquatic organisms. Cyanates are believed to be relatively nontoxic although the 96-h LC50 for mercuric thiocyanate was determined to be 120 ug.L-1 for a marine invertebrate and 180 ug.L-1 for a freshwater fish. Cyanogen chloride is toxic to fish at 40 ug.L-1. Metallo- and organocyanides: The toxicity of metallocyanides may in part be related to molecular structures, as discussed in Section 2.5 of the text. An inherent toxicity is associated with tetracyanonickelate II, dicyanoargentate I, and dicyanocuprate I. The nickel complex, which may have an accumulative mode of action, has been estimated as lethally toxic to fish at 1.0 mg.L-1 as total cyanide. The toxic silver and copper complexes may not be significant in the environment because of their removal by wastewater treatment and their rapid dissociation upon dilution of effluents. Iron cyanide complexes are extremely stable in the absence of ultraviolet or visible light and are essentially nontoxic. However, they can undergo photolysis under certain circumstances and release toxic levels of free cyanide. The inherent toxicity associated with cobalt and mercury complexes (other than mercuric thiocyanate) has not been investigated. Toxicity of cyano complexes of chromium, cadmium, zinc, and lead has not been demonstrated; however, solutions of these complexes may produce toxic levels of free cyanide. Within the organocyanides is a group of cyanohydrins (e.g. lactonitrile) which may produce sufficient HCN via hydrolysis to elicit toxic responses in short-term exposure situations. Other nitriles are less toxic in acute conditions. For example, the 100-d LC50 for rainbow trout was estimated as 1.6 mg.L-1 as acrylonitrile. Chronic toxicity has not been adequately investigated. Multiple toxicity: Binary mixtures of free cyanide plus hexavalent chromium, zinc, or ammonia resulted in more fish lethalities than predicted by either response addition or concentration addition models. However, at sublethal levels, only the NH3-HC binary mixture had an interactive effect whereas Cr-HCN and Zn-HCN combinations demonstrated independent modes of action. Binary mixtures of arsenic plus free cyanide may elicit effects at sublethal levels which are predictable according to a response addition model."
1009420,Shah and  Devi 1987,A new chelating ion-exchanger containing p-bromophenylhydroxamic acid as functional group-IV: column separations on a hydroxamic acid resin,"A new chelating resin based on macroreticular acrylonitrile-divinylbenzene copolymer and containing hydroxamic acid functional groups has been synthesized. It is highly stable in acidic and alkaline solutions. The sorption characteristics of Cu(II), Cd(II), Pb(II), Zn(II), U(VI), Cr(VI), V(V), Co(II), Ni(II), Ca(II) and Mg(II) have been investigated over the pH range 1.0-6.0. The effect of various electrolytes at different ionic strengths on the K(d) values for Cu(II), Cd(II), Pb(II) and Zn(II) has been studied systematically. Chromatographic separations of copper(II) and nickel(II) from cobalt (II), and of uranium(VI) from chromium(VI) by selective sorption at controlled pH, have been developed. The ion-exchanger can be used for purification of inorganic salts, and analysis of brass and bauxite.","A new chelating ion-exchanger containing p-bromophenylhydroxamic acid as functional group-IV: column separations on a hydroxamic acid resin Abs: A new chelating resin based on macroreticular acrylonitrile-divinylbenzene copolymer and containing hydroxamic acid functional groups has been synthesized. It is highly stable in acidic and alkaline solutions. The sorption characteristics of Cu(II), Cd(II), Pb(II), Zn(II), U(VI), Cr(VI), V(V), Co(II), Ni(II), Ca(II) and Mg(II) have been investigated over the pH range 1.0-6.0. The effect of various electrolytes at different ionic strengths on the K(d) values for Cu(II), Cd(II), Pb(II) and Zn(II) has been studied systematically. Chromatographic separations of copper(II) and nickel(II) from cobalt (II), and of uranium(VI) from chromium(VI) by selective sorption at controlled pH, have been developed. The ion-exchanger can be used for purification of inorganic salts, and analysis of brass and bauxite."
1008915,Garcia et al. 2010,Microscopic study of a ligand induced electroless plating process onto polymers,"The ligand induced electroless plating (LIEP) process was recently developed and thoroughly demonstrated with one of the most used polymers for plating processes: acrylonitrile-butadiene-styrene (ABS). This generic process is based, thanks to the use of diazonium salts as precursors, on the covalent grafting of a thin layer of poly(acrylic acid) (PAA) acting as ligand for metallic salts onto pristine polymer surfaces. This strategy takes advantage of the PAA ion exchange properties. Indeed, carboxylate groups contained in PAA allow one to complex copper ions which are eventually reduced and used as catalysts of the metallic deposition. Essentially based on ABS, ABS-PC (ABS-polycarbonate) and PA (polyamide) substrates, the present paper focuses on the role of the polymer substrate and the relationships between the macroscopic properties and microscopic characterizations such as infrared (IR), X-ray photoelectron spectroscopy (XPS), atomic force microscopy (AFM), and scanning electron microscopy (SEM). The adhesion strength of the metallic layer deposited via that LIEP process with the bulk polymer substrates was successfully compared with the adhesion of similar copper films deposited by the usual process based on chromic acid etching and palladium-based seed layer, by measuring the T-peel adhesion strength, and by carrying out the common industrial scotch tape test. Lastly, the electrical properties of the deposited layer were studied thanks to a four-point probe and scanning tunneling microscopy (STM) measurements.","Microscopic study of a ligand induced electroless plating process onto polymers Abs: The ligand induced electroless plating (LIEP) process was recently developed and thoroughly demonstrated with one of the most used polymers for plating processes: acrylonitrile-butadiene-styrene (ABS). This generic process is based, thanks to the use of diazonium salts as precursors, on the covalent grafting of a thin layer of poly(acrylic acid) (PAA) acting as ligand for metallic salts onto pristine polymer surfaces. This strategy takes advantage of the PAA ion exchange properties. Indeed, carboxylate groups contained in PAA allow one to complex copper ions which are eventually reduced and used as catalysts of the metallic deposition. Essentially based on ABS, ABS-PC (ABS-polycarbonate) and PA (polyamide) substrates, the present paper focuses on the role of the polymer substrate and the relationships between the macroscopic properties and microscopic characterizations such as infrared (IR), X-ray photoelectron spectroscopy (XPS), atomic force microscopy (AFM), and scanning electron microscopy (SEM). The adhesion strength of the metallic layer deposited via that LIEP process with the bulk polymer substrates was successfully compared with the adhesion of similar copper films deposited by the usual process based on chromic acid etching and palladium-based seed layer, by measuring the T-peel adhesion strength, and by carrying out the common industrial scotch tape test. Lastly, the electrical properties of the deposited layer were studied thanks to a four-point probe and scanning tunneling microscopy (STM) measurements."
1008466,Tarvainen 1995,Analysis of patients with allergic patch test reactions to a plastics and glues series,"839 patients were patch tested with a series of 31 plastics and glues allergens at a dermatologic clinic over a period of 7 years. 52 (6%) had a positive patch test reaction to 1 or more such allergens. Clinic charts of 47 patients (out of 52) were available for the study. All but 3 patients had dermatitis on their hands: 17 had only hand dermatitis. 25 (53%) patients' test results were of present or past relevance to their skin diseases. 11 patients (68%) with occupational allergic contact dermatitis (ACD) and 14 (45%) with non-occupational dermatitis had relevant reactions. p-tertiary-butylphenol-formaldehyde resin was the most common allergen (9 cases). 7 patients reacted to diaminodiphenylmethane. 5 patients, who had colophony allergy, reacted to abietic acid and 4 to abitol. There was no reaction to 14 test substances. Special series, such as this plastics and glues series, reveal the cause of ACD less frequently than standard series. However, there is no other way to confirm allergy to these usually industrial allergens, which can also sensitize through non-occupational exposure during hobby working or through unpolymerized monomer left in the finished plastic product.","Analysis of patients with allergic patch test reactions to a plastics and glues series Abs: 839 patients were patch tested with a series of 31 plastics and glues allergens at a dermatologic clinic over a period of 7 years. 52 (6%) had a positive patch test reaction to 1 or more such allergens. Clinic charts of 47 patients (out of 52) were available for the study. All but 3 patients had dermatitis on their hands: 17 had only hand dermatitis. 25 (53%) patients' test results were of present or past relevance to their skin diseases. 11 patients (68%) with occupational allergic contact dermatitis (ACD) and 14 (45%) with non-occupational dermatitis had relevant reactions. p-tertiary-butylphenol-formaldehyde resin was the most common allergen (9 cases). 7 patients reacted to diaminodiphenylmethane. 5 patients, who had colophony allergy, reacted to abietic acid and 4 to abitol. There was no reaction to 14 test substances. Special series, such as this plastics and glues series, reveal the cause of ACD less frequently than standard series. However, there is no other way to confirm allergy to these usually industrial allergens, which can also sensitize through non-occupational exposure during hobby working or through unpolymerized monomer left in the finished plastic product."
1008454,Maltoni et al. 1991,"Long-term carcinogenicity bioassays on industrial chemicals and man-made mineral fibers, at the Bentivoglio (BT) laboratories of the Bologna Institute of Oncology: Premises, programs, and results","After having stressed the need of primary prevention in the strategy for cancer control, the crucial role of the long-term carcinogenicity bioassays in providing scientific support to primary prevention has been focused. The state-of-the-art, the present inadequacies, the necessity of implementation, and the perspectives of the long-term carcinogenicity bioassays have been briefly reviewed. The performed and ongoing programs of carcinogenicity bioassays at the Bentivoglio (BT) Laboratories of the Bologna Institute of Oncology have been presented, together with the currently available results on several compounds of industrial and commercial relevance.","Long-term carcinogenicity bioassays on industrial chemicals and man-made mineral fibers, at the Bentivoglio (BT) laboratories of the Bologna Institute of Oncology: Premises, programs, and results Abs: After having stressed the need of primary prevention in the strategy for cancer control, the crucial role of the long-term carcinogenicity bioassays in providing scientific support to primary prevention has been focused. The state-of-the-art, the present inadequacies, the necessity of implementation, and the perspectives of the long-term carcinogenicity bioassays have been briefly reviewed. The performed and ongoing programs of carcinogenicity bioassays at the Bentivoglio (BT) Laboratories of the Bologna Institute of Oncology have been presented, together with the currently available results on several compounds of industrial and commercial relevance."
1005519,Ulitzur and  Barak 1988,Detection of genotoxicity of metallic compounds by the bacterial bioluminescence test,"Twenty metallic compounds were assayed for their genotoxic mutagenic activity by the bioluminescence test restoration of the luminescence of dark mutant of the luminous bacterium Photobacterium fischeri). The activity of the metals was tested in a liquid medium as well as on a solid medium. K2Cr2O7, MnCl2, BeCl2, KH2AsO4, ZnCl2 and Na2WO4 showed strong activity in liquid medium while AgNO3, Cd(OOCCH3)2, CoCl2, CuCl2, HgCl2, Na2SeO3 and Pb(NO3)2 were more active in the solid medium test. BaCl2, Na2MoO4, NaAsO2, NiSO4, Na2SeO4, RbCl, and SnCl2 were not active in the bioluminescence test. The correlation between the genotoxic activity of the tested metallic compounds in the bioluminescence test and other bacterial tests for genotoxic agents as well as the correlation between these results and the carcinogenicity of these compounds is discussed.","Detection of genotoxicity of metallic compounds by the bacterial bioluminescence test Abs: Twenty metallic compounds were assayed for their genotoxic mutagenic activity by the bioluminescence test restoration of the luminescence of dark mutant of the luminous bacterium Photobacterium fischeri). The activity of the metals was tested in a liquid medium as well as on a solid medium. K2Cr2O7, MnCl2, BeCl2, KH2AsO4, ZnCl2 and Na2WO4 showed strong activity in liquid medium while AgNO3, Cd(OOCCH3)2, CoCl2, CuCl2, HgCl2, Na2SeO3 and Pb(NO3)2 were more active in the solid medium test. BaCl2, Na2MoO4, NaAsO2, NiSO4, Na2SeO4, RbCl, and SnCl2 were not active in the bioluminescence test. The correlation between the genotoxic activity of the tested metallic compounds in the bioluminescence test and other bacterial tests for genotoxic agents as well as the correlation between these results and the carcinogenicity of these compounds is discussed."
1003593,Upreti et al. 2011,In vitro development of resistance to arsenite and chromium-VI in Lactobacilli strains as perspective attenuation of gastrointestinal disorder,"Inadvertent intake of inorganic arsenic and chromium through drinking water and food causing their toxic insults is a major health problem. Intestinal bacteria including Lactobacilli play important regulatory roles on intestinal homeostasis, and their loss is known to cause gastrointestinal (GI) disorders. Probiotic Lactobacilli resistance to arsenite and chromium-VI could be an importantfactorfor the perspective attenuation of Gl-disorders caused by these toxic metals/metalloid. In the present study resistance of arsenite (up to 32 ppm), Cr-VI (up to 64 ppm), and arsenite plus Cr-VI (32 ppm each) were developed under in vitro condition following chronological chronic exposures in Lactobacilli strains. Comparative study of biochemical parameters such as membrane transport enzymes and structural constituents; dehydrogenase and esterase activity tests, which are respective indicators for respiratory and energy producing processes, and the general heterotrophic activity of cells, of resistant strains showed similarities with their respective normal parent strains. The resistant strains were also found to be sensitive to antibiotics. Findings indicate that these resistant probiotic Lactobacilli would be useful in the prophylactic interventions of arsenic and chromium GI-toxicity.","In vitro development of resistance to arsenite and chromium-VI in Lactobacilli strains as perspective attenuation of gastrointestinal disorder Abs: Inadvertent intake of inorganic arsenic and chromium through drinking water and food causing their toxic insults is a major health problem. Intestinal bacteria including Lactobacilli play important regulatory roles on intestinal homeostasis, and their loss is known to cause gastrointestinal (GI) disorders. Probiotic Lactobacilli resistance to arsenite and chromium-VI could be an importantfactorfor the perspective attenuation of Gl-disorders caused by these toxic metals/metalloid. In the present study resistance of arsenite (up to 32 ppm), Cr-VI (up to 64 ppm), and arsenite plus Cr-VI (32 ppm each) were developed under in vitro condition following chronological chronic exposures in Lactobacilli strains. Comparative study of biochemical parameters such as membrane transport enzymes and structural constituents; dehydrogenase and esterase activity tests, which are respective indicators for respiratory and energy producing processes, and the general heterotrophic activity of cells, of resistant strains showed similarities with their respective normal parent strains. The resistant strains were also found to be sensitive to antibiotics. Findings indicate that these resistant probiotic Lactobacilli would be useful in the prophylactic interventions of arsenic and chromium GI-toxicity."
1000837,Choi et al. 2010,Various physico-chemical stress factors cause prophage induction in Nitrosospira multiformis 25196--an ammonia oxidizing bacteria,"Bacteriophages are viruses that infect bacteria and contribute significant changes in the overall bacterial community. Prophages are formed when temperate bacteriophages integrate their DNA into the bacterial chromosome during the lysogenic cycle of the phage infection to bacteria. The prophage (phage DNA integrated into bacterial genome) on the bacterial genome remains dormant, but can cause cell lysis under certain environmental conditions. This research examined the effect of various environmental stress factors on the ammonia oxidation and prophage induction in a model ammonia oxidizing bacteria Nitrosospira multiformis ATCC 25196. The factors included in the study were pH, temperature, organic carbon (COD), the presence of heavy metal in the form of chromium (VI) and the toxicity as potassium cyanide (KCN). The selected environmental factors are commonly encountered in wastewater treatment processes, where ammonia oxidizing bacteria play a pivotal role of converting ammonia into nitrite. All the factors could induce prophage from N. multiformis demonstrating that cell lysis due to prophage induction could be an important mechanism contributing to the frequent upset in ammonia oxidation efficiency in full scale treatment plants. Among the stress factors considered, pH in the acidic range was the most detrimental to the nitrification efficiency by N. multiformis. The number of virus like particles (VLPs) increased by 2.3E+10 at pH 5 in 5h under acidic pH conditions. The corresponding increases in VLPs at pH values of 7 and 8 were 9.67E+9 and 1.57E+10 in 5h respectively. Cell lysis due to stress resulting in phage induction seemed the primary reason for deteriorated ammonia oxidation by N. multiformis at lower concentrations of Cr (VI) and potassium cyanide. However, direct killing of N. multiformis due to the binding of Cr (VI) and potassium cyanide with cell protein as demonstrated in the literature at higher concentrations of these toxic compounds was the primary mechanism of cell lysis of N. multiformis. Organics represented by the chemical oxygen demand (COD) did not have any effect on the phage induction in N. multiformis. This AOB remained dormant at low temperature (4 degrees C) without any phage induction. Significant decrease in the number of live N. multiformis cells with a corresponding increase in the number of VLPs was recorded when the temperature was increased to 35 degrees C. Death of N. multiformis at 45 degrees C was attributed to the destruction of cell wall rather than to the phage induction.","Various physico-chemical stress factors cause prophage induction in Nitrosospira multiformis 25196--an ammonia oxidizing bacteria Abs: Bacteriophages are viruses that infect bacteria and contribute significant changes in the overall bacterial community. Prophages are formed when temperate bacteriophages integrate their DNA into the bacterial chromosome during the lysogenic cycle of the phage infection to bacteria. The prophage (phage DNA integrated into bacterial genome) on the bacterial genome remains dormant, but can cause cell lysis under certain environmental conditions. This research examined the effect of various environmental stress factors on the ammonia oxidation and prophage induction in a model ammonia oxidizing bacteria Nitrosospira multiformis ATCC 25196. The factors included in the study were pH, temperature, organic carbon (COD), the presence of heavy metal in the form of chromium (VI) and the toxicity as potassium cyanide (KCN). The selected environmental factors are commonly encountered in wastewater treatment processes, where ammonia oxidizing bacteria play a pivotal role of converting ammonia into nitrite. All the factors could induce prophage from N. multiformis demonstrating that cell lysis due to prophage induction could be an important mechanism contributing to the frequent upset in ammonia oxidation efficiency in full scale treatment plants. Among the stress factors considered, pH in the acidic range was the most detrimental to the nitrification efficiency by N. multiformis. The number of virus like particles (VLPs) increased by 2.3E+10 at pH 5 in 5h under acidic pH conditions. The corresponding increases in VLPs at pH values of 7 and 8 were 9.67E+9 and 1.57E+10 in 5h respectively. Cell lysis due to stress resulting in phage induction seemed the primary reason for deteriorated ammonia oxidation by N. multiformis at lower concentrations of Cr (VI) and potassium cyanide. However, direct killing of N. multiformis due to the binding of Cr (VI) and potassium cyanide with cell protein as demonstrated in the literature at higher concentrations of these toxic compounds was the primary mechanism of cell lysis of N. multiformis. Organics represented by the chemical oxygen demand (COD) did not have any effect on the phage induction in N. multiformis. This AOB remained dormant at low temperature (4 degrees C) without any phage induction. Significant decrease in the number of live N. multiformis cells with a corresponding increase in the number of VLPs was recorded when the temperature was increased to 35 degrees C. Death of N. multiformis at 45 degrees C was attributed to the destruction of cell wall rather than to the phage induction."
1000275,Hayashi and  Kashiwagi 2011,A Bayesian approach to probabilistic ecological risk assessment: risk comparison of nine toxic substances in Tokyo surface waters,"Quantitative risk comparison of toxic substances is necessary to decide which substances should be prioritized to achieve effective risk management. This study compared the ecological risk among nine major toxic substances (ammonia, bisphenol-A, chloroform, copper, hexavalent chromium, lead, manganese, nickel, and zinc) in Tokyo surface waters by adopting an integrated risk analysis procedure using Bayesian statistics.<br /><br /> Species sensitivity distributions of these substances were derived by using four Bayesian models. Environmental concentration distributions were derived by a hierarchical Bayesian model that explicitly considered the differences between within-site and between-site variations in environmental concentrations. Medians and confidence intervals of the expected potentially affected fraction (EPAF) of species were then computed by the Monte Carlo method.<br /><br /> The estimated EPAF values suggested that risk from nickel was highest and risk from zinc and ammonia were also high relative to other substances. The risk from copper was highest if bioavailability was not considered, although toxicity correction by a biotic ligand model greatly reduced the estimated risk. The risk from manganese was highest if a conservative risk index estimate (90% upper EPAF confidence limit) was selected.<br /><br /> It is suggested that zinc is not a predominant risk factor in Tokyo surface waters and strategic efforts are required to reduce the total ecological risk from multiple substances. The presented risk analysis procedure using EPAF and Bayesian statistics is expected to advance methodologies and practices in quantitative ecological risk comparison.","A Bayesian approach to probabilistic ecological risk assessment: risk comparison of nine toxic substances in Tokyo surface waters Abs: Quantitative risk comparison of toxic substances is necessary to decide which substances should be prioritized to achieve effective risk management. This study compared the ecological risk among nine major toxic substances (ammonia, bisphenol-A, chloroform, copper, hexavalent chromium, lead, manganese, nickel, and zinc) in Tokyo surface waters by adopting an integrated risk analysis procedure using Bayesian statistics.<br /><br /> Species sensitivity distributions of these substances were derived by using four Bayesian models. Environmental concentration distributions were derived by a hierarchical Bayesian model that explicitly considered the differences between within-site and between-site variations in environmental concentrations. Medians and confidence intervals of the expected potentially affected fraction (EPAF) of species were then computed by the Monte Carlo method.<br /><br /> The estimated EPAF values suggested that risk from nickel was highest and risk from zinc and ammonia were also high relative to other substances. The risk from copper was highest if bioavailability was not considered, although toxicity correction by a biotic ligand model greatly reduced the estimated risk. The risk from manganese was highest if a conservative risk index estimate (90% upper EPAF confidence limit) was selected.<br /><br /> It is suggested that zinc is not a predominant risk factor in Tokyo surface waters and strategic efforts are required to reduce the total ecological risk from multiple substances. The presented risk analysis procedure using EPAF and Bayesian statistics is expected to advance methodologies and practices in quantitative ecological risk comparison."
999143,Ennever and  Rosenkranz 1986,"Short-term test results for NTP noncarcinogens: an alternate, more predictive battery","A battery of short-term tests used to predict whether or not a chemical is a carcinogen must be both sensitive (correctly identifying carcinogens) and specific (correctly identifying noncarcinogens). A recent publication [Shelby and Stasiewicz, 1984, Environ Mutagen 6:871-876] of results in four short-term tests for 70 noncarcinogens tested under the aegis of the National Toxicology Program (NTP) indicates that the battery of short-term tests lacked specificity. We have analyzed these results using the Carcinogen Prediction and Battery Selection (CPBS) procedure and calculated that the specificity of the NTP battery is indeed very low, i.e., 0.50. Using published data from NTP, the Gene Tox program of EPA, and the collaborative study of the WHO International Programme on Chemical Safety, we have constructed an alternate battery that has fewer false positives; this battery has a specificity of 0.80. Thus, the lack of specificity of the original NTP battery does not imply that no set of short-term tests is able to predict carcinogenicity accurately.","Short-term test results for NTP noncarcinogens: an alternate, more predictive battery Abs: A battery of short-term tests used to predict whether or not a chemical is a carcinogen must be both sensitive (correctly identifying carcinogens) and specific (correctly identifying noncarcinogens). A recent publication [Shelby and Stasiewicz, 1984, Environ Mutagen 6:871-876] of results in four short-term tests for 70 noncarcinogens tested under the aegis of the National Toxicology Program (NTP) indicates that the battery of short-term tests lacked specificity. We have analyzed these results using the Carcinogen Prediction and Battery Selection (CPBS) procedure and calculated that the specificity of the NTP battery is indeed very low, i.e., 0.50. Using published data from NTP, the Gene Tox program of EPA, and the collaborative study of the WHO International Programme on Chemical Safety, we have constructed an alternate battery that has fewer false positives; this battery has a specificity of 0.80. Thus, the lack of specificity of the original NTP battery does not imply that no set of short-term tests is able to predict carcinogenicity accurately."
995782,Hutcheson et al. 1975,Studies of nutritional safety of some heavy metals in mice,"Heavy metals have been proposed as nutrient markers to allow the accurate determination of the time of passage, nutrient intake, or apparent utilization of multiple nutrients. In order to evaluate possible toxic effects of scandium, chromium, lanthanum, samarium, europium, dysprosium, terbium, thulium, and ytterbium oxides, and barium sulfate upon growth, general development, reproduction, and lactation, mice were fed different levels of these compounds for three generations. The amount of elements fed were 0,110, 100, and 1000 times the use amount. The use amounts were (in ppm2.) : Sc, 0.12; Cr, 0.02; La.0.40;; Sm. 0.80; Eu, 0.036:TB, 1.20; Dy, 1.20; Tm. 0.08; Tb, 0.12; and Ba, 0.008. The use amount was one-fifth of the concentration required for activation analysis. Mortality and morbidity were negligible. No consistent growth rate changes were observed; however, different groups showed different growth rates during different generations. The number of mice born showed no significant differences amoung treatment groups. Survival, growth rate, hematology, morphological development, maturation, reproduction, and lactational performance were comparable in mice fed the different levels of 10 heavy metal oxides to those mice fed the basal diet.","Studies of nutritional safety of some heavy metals in mice Abs: Heavy metals have been proposed as nutrient markers to allow the accurate determination of the time of passage, nutrient intake, or apparent utilization of multiple nutrients. In order to evaluate possible toxic effects of scandium, chromium, lanthanum, samarium, europium, dysprosium, terbium, thulium, and ytterbium oxides, and barium sulfate upon growth, general development, reproduction, and lactation, mice were fed different levels of these compounds for three generations. The amount of elements fed were 0,110, 100, and 1000 times the use amount. The use amounts were (in ppm2.) : Sc, 0.12; Cr, 0.02; La.0.40;; Sm. 0.80; Eu, 0.036:TB, 1.20; Dy, 1.20; Tm. 0.08; Tb, 0.12; and Ba, 0.008. The use amount was one-fifth of the concentration required for activation analysis. Mortality and morbidity were negligible. No consistent growth rate changes were observed; however, different groups showed different growth rates during different generations. The number of mice born showed no significant differences amoung treatment groups. Survival, growth rate, hematology, morphological development, maturation, reproduction, and lactational performance were comparable in mice fed the different levels of 10 heavy metal oxides to those mice fed the basal diet."
994166,Lee et al. 2001,Contact dermatitis in Korean dental technicians,"The high risk of occupational contact dermatitis in dental personnel are well accepted throughout the world. There are few reports concerning occupational skin disease in dental personnel in Korea. The purposes of this study were to investigate the frequency, characteristics and causative factors of contact dermatitis in Korean dental technicians. Recording of personal history, physical examination and patch tests with the Korean standard series and dental screening series were performed in 49 dental technicians. Most of the subjects were exposed to a variety of compounds, including acrylics, metals, plaster, alginate, etc. 22 (44.9%) subjects had contact dermatitis, present or past, and the site involved was the hand in all 22. The most common clinical feature of hand dermatitis was itching (77.3%); scaling, fissuring and erythema were other common clinical features. Metals, including potassium dichromate (24.5%), nickel sulfate (18.4%), mercury ammonium chloride (16.3%), cobalt chloride (12.2%) and palladium chloride (10.2%), showed high positive rates in patch test results of 49 dental technicians. 7 positive reactions to the various acrylics were found in 3 subjects. In our study, the frequency and clinical features of the contact dermatitis showed a similarity to other reports, though the patch test results were somewhat different; a higher patch-positive reaction to metals and a relatively lower patch-positive reaction to acrylics than the patch test results reported in Europe.","Contact dermatitis in Korean dental technicians Abs: The high risk of occupational contact dermatitis in dental personnel are well accepted throughout the world. There are few reports concerning occupational skin disease in dental personnel in Korea. The purposes of this study were to investigate the frequency, characteristics and causative factors of contact dermatitis in Korean dental technicians. Recording of personal history, physical examination and patch tests with the Korean standard series and dental screening series were performed in 49 dental technicians. Most of the subjects were exposed to a variety of compounds, including acrylics, metals, plaster, alginate, etc. 22 (44.9%) subjects had contact dermatitis, present or past, and the site involved was the hand in all 22. The most common clinical feature of hand dermatitis was itching (77.3%); scaling, fissuring and erythema were other common clinical features. Metals, including potassium dichromate (24.5%), nickel sulfate (18.4%), mercury ammonium chloride (16.3%), cobalt chloride (12.2%) and palladium chloride (10.2%), showed high positive rates in patch test results of 49 dental technicians. 7 positive reactions to the various acrylics were found in 3 subjects. In our study, the frequency and clinical features of the contact dermatitis showed a similarity to other reports, though the patch test results were somewhat different; a higher patch-positive reaction to metals and a relatively lower patch-positive reaction to acrylics than the patch test results reported in Europe."
988722,Xiong and  Peng 1999,Effect of the content of ammonium dichromate in dichromated gelatin on Cr 2P3/2 X-ray photoelectron spectroscopy,"The effect of the content of (NH(4))(2)Cr(2)O(7) in dichromated gelatin (DCG) on the binding energy of the Cr 2P(3/2) level was studied with x-ray photoelectron spectroscopy. It was found that the binding energy of the Cr 2P(3/2) level of chromium in DCG is lower than that of pure ammonium dichromate. When the content of (NH(4))(2)Cr(2)O(7) is not greater than 1%, the chromium in DCG has only one state, near 577.5 eV; when this content is between 1% and 20%, the chromium in DCG has two states, near 577.5 and 579.1 eV. The relative contents of these two states change with the content of (NH(4))(2)Cr(2)O(7). As the (NH(4))(2)Cr(2)O(7) content increases, the relative content of the state near 577.5 eV decreases almost linearly, but its absolute content first increases, then reaches a maximum at ~10% (NH(4))(2)Cr(2)O(7), and finally decreases. In addition, the absolute content of the state near 577.5 eV changes very slowly between 5% and 15% (NH(4))(2)Cr(2)O(7). According to these experimental results and holography data reported in the literature, it is inferred that the chromium of the state near 577.5 eV is the chromium that forms the latent image center after exposure and then forms the hologram after development. As a result the basis for the optimum content of (NH(4))(2)Cr(2)O(7) is found, and an approach to increasing sensitivity is suggested through this experiment.","Effect of the content of ammonium dichromate in dichromated gelatin on Cr 2P3/2 X-ray photoelectron spectroscopy Abs: The effect of the content of (NH(4))(2)Cr(2)O(7) in dichromated gelatin (DCG) on the binding energy of the Cr 2P(3/2) level was studied with x-ray photoelectron spectroscopy. It was found that the binding energy of the Cr 2P(3/2) level of chromium in DCG is lower than that of pure ammonium dichromate. When the content of (NH(4))(2)Cr(2)O(7) is not greater than 1%, the chromium in DCG has only one state, near 577.5 eV; when this content is between 1% and 20%, the chromium in DCG has two states, near 577.5 and 579.1 eV. The relative contents of these two states change with the content of (NH(4))(2)Cr(2)O(7). As the (NH(4))(2)Cr(2)O(7) content increases, the relative content of the state near 577.5 eV decreases almost linearly, but its absolute content first increases, then reaches a maximum at ~10% (NH(4))(2)Cr(2)O(7), and finally decreases. In addition, the absolute content of the state near 577.5 eV changes very slowly between 5% and 15% (NH(4))(2)Cr(2)O(7). According to these experimental results and holography data reported in the literature, it is inferred that the chromium of the state near 577.5 eV is the chromium that forms the latent image center after exposure and then forms the hologram after development. As a result the basis for the optimum content of (NH(4))(2)Cr(2)O(7) is found, and an approach to increasing sensitivity is suggested through this experiment."
980911,Shah et al. 2009,Sorption isotherms and kinetics of chromium uptake from wastewater using natural sorbent material,"Chromium (VI) which exists in many industrial wastewater is considered highly toxic. The aim of the present investigation was to study the reduction of chromium (VI) to chromium (III) and then removing it with the help of weathered basalt andesite products. Reduction of the chromium (VI) to chromium (III) by hydrazinium sulfate was investigated. The influence of hydronium ion concentration, contact time, hydrazinium sulphate dosage and temperature has been tested in batch runs. The process was found to be acid, temperature and concentration dependent. The suitability of weathered basalt andesite products as a potential sorbent was assessed for the removal of chromium (III) following batch mode of operation. The effect of various parameters such as hydronium ion concentration, shaking time, sorbent dose, initial metal ion concentration and temperature on the removal of chromium (III) front aqueous solution was studied. Thermodynamic parameters (Delta H degrees, Delta S degrees and Delta G degrees) for the sorption process were evaluated. Analysis of sorption obtained results showed that the sorption pattern followed the Freundlich, Langmuir and Dubinin-Kaganer-Radushkevich isotherms. The process Follows pseudo second order rate and surface diffusion is identified as the predominating mechanism. The sorption process was shown to be reversible by the recovery of sorbed chromium (III) upon extraction with 0.5 M nitric acid. The sorbent, before and after sorption, was characterized by fourier transform infrared spectrometer, X-ray diffraction, scanning electron microscope, transmision electron microscope and thermogravimetric analyse methodes. An increase in crystallanity after sorption of chromium was observed. An industrial effluent was successfully treated with the same sorbent with convincing results.","Sorption isotherms and kinetics of chromium uptake from wastewater using natural sorbent material Abs: Chromium (VI) which exists in many industrial wastewater is considered highly toxic. The aim of the present investigation was to study the reduction of chromium (VI) to chromium (III) and then removing it with the help of weathered basalt andesite products. Reduction of the chromium (VI) to chromium (III) by hydrazinium sulfate was investigated. The influence of hydronium ion concentration, contact time, hydrazinium sulphate dosage and temperature has been tested in batch runs. The process was found to be acid, temperature and concentration dependent. The suitability of weathered basalt andesite products as a potential sorbent was assessed for the removal of chromium (III) following batch mode of operation. The effect of various parameters such as hydronium ion concentration, shaking time, sorbent dose, initial metal ion concentration and temperature on the removal of chromium (III) front aqueous solution was studied. Thermodynamic parameters (Delta H degrees, Delta S degrees and Delta G degrees) for the sorption process were evaluated. Analysis of sorption obtained results showed that the sorption pattern followed the Freundlich, Langmuir and Dubinin-Kaganer-Radushkevich isotherms. The process Follows pseudo second order rate and surface diffusion is identified as the predominating mechanism. The sorption process was shown to be reversible by the recovery of sorbed chromium (III) upon extraction with 0.5 M nitric acid. The sorbent, before and after sorption, was characterized by fourier transform infrared spectrometer, X-ray diffraction, scanning electron microscope, transmision electron microscope and thermogravimetric analyse methodes. An increase in crystallanity after sorption of chromium was observed. An industrial effluent was successfully treated with the same sorbent with convincing results."
963843,Srivastava and  Jain 2011,In-situ monitoring of chromium cytotoxicity in sugarcane,"The potential of in-situ monitoring of cytotoxic effects of chromium through root-tip assay was studied in a sugarcane cultivar CoLk 8102 (Saccharum s. hybrid). Sugarcane setts supplied with graded concentrations of chromium (VI), exhibited a reduction of 85.92 and 95.10 % in mean root length at 40 and 80 ppm Cr dosages along with 61.25 and 82.50% reduction in mean root number/node respectively. Mitotic index of root tip cells of treated 'setts declined and the frequency of aberrant mitotic phases increased pan passu to the increasing chromium concentration. To compare and quantify the effect of graded chromium dosages on frequency of chromosome aberrations vis-a-vis inhibition of mitotic activity, a 'Decretion factor' (D.F.) has been used for the first time. The value of DF increased with the increase in the chromium dosages. The increase in chromosome aberration frequency was low at low chromium dosages (1 or 2 ppm), but the high Cr dosages (40 and 80 ppm), induced sharp reduction in mitotic efficiency of root system along with anomalies in the process of cell division and induced chromosome aberrations in sugarcane root meristem, which in turn affected the over all plant growth.","In-situ monitoring of chromium cytotoxicity in sugarcane Abs: The potential of in-situ monitoring of cytotoxic effects of chromium through root-tip assay was studied in a sugarcane cultivar CoLk 8102 (Saccharum s. hybrid). Sugarcane setts supplied with graded concentrations of chromium (VI), exhibited a reduction of 85.92 and 95.10 % in mean root length at 40 and 80 ppm Cr dosages along with 61.25 and 82.50% reduction in mean root number/node respectively. Mitotic index of root tip cells of treated 'setts declined and the frequency of aberrant mitotic phases increased pan passu to the increasing chromium concentration. To compare and quantify the effect of graded chromium dosages on frequency of chromosome aberrations vis-a-vis inhibition of mitotic activity, a 'Decretion factor' (D.F.) has been used for the first time. The value of DF increased with the increase in the chromium dosages. The increase in chromosome aberration frequency was low at low chromium dosages (1 or 2 ppm), but the high Cr dosages (40 and 80 ppm), induced sharp reduction in mitotic efficiency of root system along with anomalies in the process of cell division and induced chromosome aberrations in sugarcane root meristem, which in turn affected the over all plant growth."
956627,Ambushe et al. 2009,Speciation of chromium in cow's milk by solid-phase extraction/dynamic reaction cell inductively coupled plasma mass spectrometry (DRC-ICP-MS),,Speciation of chromium in cow's milk by solid-phase extraction/dynamic reaction cell inductively coupled plasma mass spectrometry (DRC-ICP-MS) Abs: 
947460,Matos et al. 2009,Speciation of chromium in river water samples contaminated with leather effluents by flame atomic absorption spectrometry after separation/preconcentration by cloud point extraction,,Speciation of chromium in river water samples contaminated with leather effluents by flame atomic absorption spectrometry after separation/preconcentration by cloud point extraction Abs: 
939934,Kumar et al. 2009,Cytoprotection against Cr(6+)-induced DNA damage by alpha-lipoic acid: implications in reducing occupational cancer risk,"Alpha-lipoic acid (LA), the metabolic antioxidant, was evaluated for its potential to protect against Cr(6+)-induced DNA damage. Potassium dichromate was administered to Swiss albino mice orally ad libitum at the doses of 5, 10 or 25 mg/kg body weight in drinking water to set DNA damage in cells, which was characterized in mouse peripheral blood mononuclear cells and bone marrow cells using single-cell gel electrophoresis and analyses of generated comets for Tail moment, Tail DNA and Tail length. DNA damage was dose dependent. Cytoprotection by LA was remarkable. LA (5, 10 and 25 mg/kg body weight intraperitoneally) in pre-, co- and post-toxicant administration schedule abrogated DNA damage substantially in both cell types. Protection by LA was also dose dependent. LA annulled DNA damage by Cr(6+) in plasmid relaxation assay. A negligible DNA damage resulted during interaction of Cr(6+) and LA. Compared to ascorbate, LA emerged as a better antioxidant and least DNA damaging. In conclusion, our study advocated an experimental therapeutic research potential in LA against Cr(6+)-induced DNA damage for reduction of occupational cancer risk in humans.","Cytoprotection against Cr(6+)-induced DNA damage by alpha-lipoic acid: implications in reducing occupational cancer risk Abs: Alpha-lipoic acid (LA), the metabolic antioxidant, was evaluated for its potential to protect against Cr(6+)-induced DNA damage. Potassium dichromate was administered to Swiss albino mice orally ad libitum at the doses of 5, 10 or 25 mg/kg body weight in drinking water to set DNA damage in cells, which was characterized in mouse peripheral blood mononuclear cells and bone marrow cells using single-cell gel electrophoresis and analyses of generated comets for Tail moment, Tail DNA and Tail length. DNA damage was dose dependent. Cytoprotection by LA was remarkable. LA (5, 10 and 25 mg/kg body weight intraperitoneally) in pre-, co- and post-toxicant administration schedule abrogated DNA damage substantially in both cell types. Protection by LA was also dose dependent. LA annulled DNA damage by Cr(6+) in plasmid relaxation assay. A negligible DNA damage resulted during interaction of Cr(6+) and LA. Compared to ascorbate, LA emerged as a better antioxidant and least DNA damaging. In conclusion, our study advocated an experimental therapeutic research potential in LA against Cr(6+)-induced DNA damage for reduction of occupational cancer risk in humans."
938846,Chanh and  Chanvattey 1967,"[Comparative study of sodium chromate, molybdate, tungstate and metavandate. V. Experiments on pigeons, chickens and rats]","The comparative toxicity of sodium-chromate (7775113), sodium-molybdate (13466165), sodium-tungstate (11120017), and sodium-metavanadate (13718268) was investigated in Columba-domestica-pigeons, Rhode-Island-Red-chicks, and Wistar-rats. Solutions were prepared containing 100 millimoles (mmol) molybdate, 50mmol chromate, or 10mmol tungstate or metavanadate in 100 milliliters of isotonic saline solution. The solutions were administered to anesthetized animals by slow intravenous perfusion until the animals died. Electrocardiographic recordings were made and stoppage of all electrical activity was the criterion for death. Average lethal doses were calculated. Sodium-metavanadate was the most toxic in all species. Sodium-molybdate was the least toxic. Rats were most resistant to sodium-chromate, and pigeons to the other three compounds. The authors conclude that the toxicity of each of the salts tested varies greatly from one animal species to another, and the relative resistance of the different species varies from one salt to another. (French)","[Comparative study of sodium chromate, molybdate, tungstate and metavandate. V. Experiments on pigeons, chickens and rats] Abs: The comparative toxicity of sodium-chromate (7775113), sodium-molybdate (13466165), sodium-tungstate (11120017), and sodium-metavanadate (13718268) was investigated in Columba-domestica-pigeons, Rhode-Island-Red-chicks, and Wistar-rats. Solutions were prepared containing 100 millimoles (mmol) molybdate, 50mmol chromate, or 10mmol tungstate or metavanadate in 100 milliliters of isotonic saline solution. The solutions were administered to anesthetized animals by slow intravenous perfusion until the animals died. Electrocardiographic recordings were made and stoppage of all electrical activity was the criterion for death. Average lethal doses were calculated. Sodium-metavanadate was the most toxic in all species. Sodium-molybdate was the least toxic. Rats were most resistant to sodium-chromate, and pigeons to the other three compounds. The authors conclude that the toxicity of each of the salts tested varies greatly from one animal species to another, and the relative resistance of the different species varies from one salt to another. (French)"
935476,Tsoi and  Sze-Yin leung 2010,Simultaneous determination of seven elemental species in estuarine waters by LC-ICP-DRC-MS,,Simultaneous determination of seven elemental species in estuarine waters by LC-ICP-DRC-MS Abs: 
935067,Wyszkowski and  Radziemska 2010,Effects of chromium(III and VI) on spring barley and maize biomass yield and content of nitrogenous compounds,"The aim of this study was to (1) determine the effects of trivalent Cr(III) or hexavalent chromium Cr(VI) soil contamination on biomass yield and nitrogenous compound content of spring barley (Hordeum vulgare L.) as the main crop and subsequently maize (Zea mays L.) grown successively, and (2) examine whether the neutralizing additives applied (compost, zeolite, and calcium oxide) may be effective in reducing adverse impact of chromium (Cr) on crops. Spring barley yield was markedly decreased by Cr compounds, particularly Cr(VI). In contrast, maize yield was significantly increased by Cr(VI). Hexavalent Cr exerted a greater effect than the Cr(III) form on nitrogen levels in spring barley. Chromium significantly increased ammonia nitrogen content in maize. The accumulation of NO(3)(-)-N in plants treated with Cr(VI) was lower than in controls. The application of compost, zeolite, and calcium oxide onto the soil increased yield of maize only in pots containing Cr(III). Neutralizing additives exerted a positive, increased effect on the N-total content of maize but not spring barley, which was apparent with calcium oxide. Accumulation of NH(4)(+)-N in maize in pots with Cr(VI) was increased by all additives applied. The content of nitrate nitrogen in spring barley was predominantly affected by addition of compost and calcium oxide into the soil, producing a significant rise in NO(3)(-)-N content. Chromium, especially Cr(VI), used at doses of 100 and 150 mg/kg soil exerted adverse effects in treated plants, particularly spring barley.","Effects of chromium(III and VI) on spring barley and maize biomass yield and content of nitrogenous compounds Abs: The aim of this study was to (1) determine the effects of trivalent Cr(III) or hexavalent chromium Cr(VI) soil contamination on biomass yield and nitrogenous compound content of spring barley (Hordeum vulgare L.) as the main crop and subsequently maize (Zea mays L.) grown successively, and (2) examine whether the neutralizing additives applied (compost, zeolite, and calcium oxide) may be effective in reducing adverse impact of chromium (Cr) on crops. Spring barley yield was markedly decreased by Cr compounds, particularly Cr(VI). In contrast, maize yield was significantly increased by Cr(VI). Hexavalent Cr exerted a greater effect than the Cr(III) form on nitrogen levels in spring barley. Chromium significantly increased ammonia nitrogen content in maize. The accumulation of NO(3)(-)-N in plants treated with Cr(VI) was lower than in controls. The application of compost, zeolite, and calcium oxide onto the soil increased yield of maize only in pots containing Cr(III). Neutralizing additives exerted a positive, increased effect on the N-total content of maize but not spring barley, which was apparent with calcium oxide. Accumulation of NH(4)(+)-N in maize in pots with Cr(VI) was increased by all additives applied. The content of nitrate nitrogen in spring barley was predominantly affected by addition of compost and calcium oxide into the soil, producing a significant rise in NO(3)(-)-N content. Chromium, especially Cr(VI), used at doses of 100 and 150 mg/kg soil exerted adverse effects in treated plants, particularly spring barley."
925282,Khan et al. 2010,Nephroprotective action of tocotrienol-rich fraction (TRF) from palm oil against potassium dichromate (K 2 Cr 2 O 7)-induced acute renal injury in rats,"Industrial and occupational exposure to chromium compounds, particularly hexavalent chromium (Cr(VI))-containing compounds are often known to cause acute renal injury (ARI) in humans and animals. Its nephrotoxicity is associated with an increased formation of reactive oxygen species and lipid peroxidation in renal tissue. Recent studies suggest that antioxidants of the vitamin E family have protective effects against metal toxicity. Tocotrienols are known to have greater antioxidant activity than tocopherols and protect more efficiently against some free radical-related diseases than does tocopherols. In the present study, ARI induced by potassium dichromate (K(2)Cr(2)O(7)) has been used as a model to investigate the possible nephroprotective effect of tocotrienol-rich fraction (TRF) from palm oil. Wistar male rats having an average body weight (bw) of 210 g were divided into four groups. The first group was taken as control and injected with vehicle alone while the second group was drug control and ingested with TRF (200mg/kg, bw, orally, once daily for 21 days); the third group served as toxicant and was pre-treated with saline, followed by a single subcutaneous (SC) injection of K(2)Cr(2)O(7) (15 mg/kg bw). The fourth group was pre-treated with TRF and subsequently injected with K(2)Cr(2)O(7) (same dose as for the third group). Renal functions, oxidative and nitrosative stress were evaluated on days 0, 1, 2, 4, 7, 11 and 14 after treatment with K(2)Cr(2)O(7). The results revealed altered proximal tubular function; decreased glomerular filtration accompanied by oxidative damage 48 h after exposure to dichromate; while in the TRF-treated group proximal reabsorptive function, glomerular function and the cellular redox status were sustained. These results were further supported and confirmed by histological findings. The study suggests that TRF is effective in preventing K(2)Cr(2)O(7)-induced acute renal injury, but more studies are needed to confirm the effects of TRF as a nephroprotective agent.","Nephroprotective action of tocotrienol-rich fraction (TRF) from palm oil against potassium dichromate (K 2 Cr 2 O 7)-induced acute renal injury in rats Abs: Industrial and occupational exposure to chromium compounds, particularly hexavalent chromium (Cr(VI))-containing compounds are often known to cause acute renal injury (ARI) in humans and animals. Its nephrotoxicity is associated with an increased formation of reactive oxygen species and lipid peroxidation in renal tissue. Recent studies suggest that antioxidants of the vitamin E family have protective effects against metal toxicity. Tocotrienols are known to have greater antioxidant activity than tocopherols and protect more efficiently against some free radical-related diseases than does tocopherols. In the present study, ARI induced by potassium dichromate (K(2)Cr(2)O(7)) has been used as a model to investigate the possible nephroprotective effect of tocotrienol-rich fraction (TRF) from palm oil. Wistar male rats having an average body weight (bw) of 210 g were divided into four groups. The first group was taken as control and injected with vehicle alone while the second group was drug control and ingested with TRF (200mg/kg, bw, orally, once daily for 21 days); the third group served as toxicant and was pre-treated with saline, followed by a single subcutaneous (SC) injection of K(2)Cr(2)O(7) (15 mg/kg bw). The fourth group was pre-treated with TRF and subsequently injected with K(2)Cr(2)O(7) (same dose as for the third group). Renal functions, oxidative and nitrosative stress were evaluated on days 0, 1, 2, 4, 7, 11 and 14 after treatment with K(2)Cr(2)O(7). The results revealed altered proximal tubular function; decreased glomerular filtration accompanied by oxidative damage 48 h after exposure to dichromate; while in the TRF-treated group proximal reabsorptive function, glomerular function and the cellular redox status were sustained. These results were further supported and confirmed by histological findings. The study suggests that TRF is effective in preventing K(2)Cr(2)O(7)-induced acute renal injury, but more studies are needed to confirm the effects of TRF as a nephroprotective agent."
920982,Smiri et al. 2010,RETRACTED: Redox regulation of the glutathione reductase/iso-glutaredoxin system in germinating pea seed exposed to cadmium,"This article has been retracted: please see Elsevier Policy on Article Withdrawal (http://www.elsevier.com/locate/withdrawalpolicy). The editors would like to confirm the retraction of this paper at the request of the co-authors who had no prior knowledge on the actions of the lead author. This article contains data that was duplicated in: Smiri M, Chaoui A, Rouhier N, Gelhaye E, Jacquot JP, El Ferjani E. Cadmium Affects the Glutathione/Glutaredoxin System in Germinating Pea Seeds. Biol. Trace Elem. Res., 142 (2010) 93-105, doi:10.1007/s12011-010-8749-3; Smiri M, Chaoui A, Rouhier N, Gelhaye E, Jacquot JP, El Ferjani E. Effect of cadmium on resumption of respiration in cotyledons of germinating pea seeds. Ecotox. Environ. Safe., 73 (2010) 1246-1254, doi:10.1016/j.ecoenv.2010.05.015; Smiri M, Chaoui A, Rouhier N, Gelhaye E, Jacquot JP, El Ferjani E. NAD pattern and NADH oxidase activity in pea (Pisum sativum L.) under cadmium toxicity. Physiol. Mol. Biol. Plants, 16 (2010) 305-315, doi:10.1007/s12298-010-0033-7; Smiri M, Chaoui A, Rouhier N, Gelhaye E, Jacquot JP, El Ferjani E. Oxidative damage and redox change in pea seeds treated with cadmium. C. R. Biol., 333 (2010) 801-807, doi:10.1016/j.crvi.2010.09.002; Smiri M, Chaoui A, Rouhier N, Kamel C, Gelhaye E, Jacquot JP, El Ferjani E. Cadmium induced mitochondrial redox changes in germinating pea seed. BioMetals, 23 (2010) 973-984, doi:10.1007/s10534-010-9344-y. The co-authors apologize for this unfortunate incident.","RETRACTED: Redox regulation of the glutathione reductase/iso-glutaredoxin system in germinating pea seed exposed to cadmium Abs: This article has been retracted: please see Elsevier Policy on Article Withdrawal (http://www.elsevier.com/locate/withdrawalpolicy). The editors would like to confirm the retraction of this paper at the request of the co-authors who had no prior knowledge on the actions of the lead author. This article contains data that was duplicated in: Smiri M, Chaoui A, Rouhier N, Gelhaye E, Jacquot JP, El Ferjani E. Cadmium Affects the Glutathione/Glutaredoxin System in Germinating Pea Seeds. Biol. Trace Elem. Res., 142 (2010) 93-105, doi:10.1007/s12011-010-8749-3; Smiri M, Chaoui A, Rouhier N, Gelhaye E, Jacquot JP, El Ferjani E. Effect of cadmium on resumption of respiration in cotyledons of germinating pea seeds. Ecotox. Environ. Safe., 73 (2010) 1246-1254, doi:10.1016/j.ecoenv.2010.05.015; Smiri M, Chaoui A, Rouhier N, Gelhaye E, Jacquot JP, El Ferjani E. NAD pattern and NADH oxidase activity in pea (Pisum sativum L.) under cadmium toxicity. Physiol. Mol. Biol. Plants, 16 (2010) 305-315, doi:10.1007/s12298-010-0033-7; Smiri M, Chaoui A, Rouhier N, Gelhaye E, Jacquot JP, El Ferjani E. Oxidative damage and redox change in pea seeds treated with cadmium. C. R. Biol., 333 (2010) 801-807, doi:10.1016/j.crvi.2010.09.002; Smiri M, Chaoui A, Rouhier N, Kamel C, Gelhaye E, Jacquot JP, El Ferjani E. Cadmium induced mitochondrial redox changes in germinating pea seed. BioMetals, 23 (2010) 973-984, doi:10.1007/s10534-010-9344-y. The co-authors apologize for this unfortunate incident."
917954,Lin et al. 2011,Polyacrylonitrile/ferrous chloride composite porous nanofibers and their strong Cr-removal performance,,Polyacrylonitrile/ferrous chloride composite porous nanofibers and their strong Cr-removal performance Abs: 
916159,Xu et al. 2011,Reduction of hexavalent chromium by Pannonibacter phragmitetus LSSE-09 stimulated with external electron donors under alkaline conditions,"A novel Cr (VI) resistant bacterial strain LSSE-09, identified as Pannonibacter phragmitetus, was isolated from industrial sludge. It has strong aerobic and anaerobic Cr (VI)-reduction potential under alkaline conditions. At 37 °C and pH 9.0, growing cells of strain LSSE-09 could completely reduce 100 and 1000 mg L(-1) Cr (VI)-Cr (III) within 9 and 24h, respectively under aerobic condition. Resting cells showed higher anaerobic reduction potential with the rate of 1.46 mg g(-1)((dry weight))min(-1), comparing with their aerobic reduction rate, 0.21 mg g(-1)min(-1). External electron donors, such as lactate, acetate, formate, pyruvate, citrate and glucose could highly increase the reduction rate, especially for aerobic reduction. The presence of 3000 mg L(-1) acetate enhanced anaerobic and aerobic Cr (VI)-reduction rates up to 9.47 mg g(-1)min(-1) and 4.42 mg g(-1)min(-1), respectively, which were 5 and 20 times faster than those without it. Strain LSSE-09 retained high activities over six batch cycles and NO(3)(-) and SO(4)(2-) had slightly negative effects on Cr (VI)-reduction rates. The results suggest that strain LSSE-09 has potential application for Cr (VI) detoxification in alkaline wastewater.","Reduction of hexavalent chromium by Pannonibacter phragmitetus LSSE-09 stimulated with external electron donors under alkaline conditions Abs: A novel Cr (VI) resistant bacterial strain LSSE-09, identified as Pannonibacter phragmitetus, was isolated from industrial sludge. It has strong aerobic and anaerobic Cr (VI)-reduction potential under alkaline conditions. At 37 °C and pH 9.0, growing cells of strain LSSE-09 could completely reduce 100 and 1000 mg L(-1) Cr (VI)-Cr (III) within 9 and 24h, respectively under aerobic condition. Resting cells showed higher anaerobic reduction potential with the rate of 1.46 mg g(-1)((dry weight))min(-1), comparing with their aerobic reduction rate, 0.21 mg g(-1)min(-1). External electron donors, such as lactate, acetate, formate, pyruvate, citrate and glucose could highly increase the reduction rate, especially for aerobic reduction. The presence of 3000 mg L(-1) acetate enhanced anaerobic and aerobic Cr (VI)-reduction rates up to 9.47 mg g(-1)min(-1) and 4.42 mg g(-1)min(-1), respectively, which were 5 and 20 times faster than those without it. Strain LSSE-09 retained high activities over six batch cycles and NO(3)(-) and SO(4)(2-) had slightly negative effects on Cr (VI)-reduction rates. The results suggest that strain LSSE-09 has potential application for Cr (VI) detoxification in alkaline wastewater."
903570,Pam-Huu-Chanh 1965,"The comparative toxicity of sodium chromate, molybdate, tungstate and metavanadate: II. Experiments on rabbits","The toxicities of sodium-chromate (7775113), sodium-molybdate (7631950), sodium-tungstate (11120017), and sodium-metavanadate (11105069) were investigated in Wistar-rats and Swiss-mice. The 24 hour maximum dose never fatal (MDNF) and minimum dose always fatal (mDAF) were determined, together with the median lethal dose (LD50), for each of the compounds. Clinical investigations of the symptomatology of intoxication were conducted. Experiments were performed using 2600 rats and 3000 mice. Symptomatology was similar in mice and rats during intoxication by each of the compounds. Animals given infra lethal doses of sodium-chromate showed no signs of poisoning; those treated with sodium-metavanadate showed signs of adynamia; and those given sodium-molybdate and sodium-tungstate showed prostration and a state of lethargy. Recuperation occurred in less than 1 hour after intoxication with sodium-molybdate, whereas there was a long coma and slow recovery in those given sodium-molybdate. Lethal doses given between MDNF and mDAF of the compounds produced the same poisoning syndrome; prostration after sodium-metavanadate was accompanied by some agitation. For sodium-chromate, the MDNF and mDAF were 0.13 and 0.34 millimoles per kilogram (mmol/kg), respectively, for mice and 0.20 and 0.75mmol/kg, respectively, for rats; LD50s were between 0.32 and 0.33mmol/kg for mice and between 0.375 and 0.37mmol/kg for rats. For sodium-molybdate, MDNF was 0.80mmol/kg for mice and 1.45mmol/kg for rats; mDAF was 1.85 and 3.50mmol/kg for mice and rats, respectively. LD50 ranged between 1.15 and 1.35mmol/kg for mice and 2.32 and 2.44mmol/kg for rats. For sodium-tungstate, MDNF was 0.30 and 0.20mmol/kg, and mDAF was 0.60 and 1.00mmol/kg for mice and rats, respectively. LD50s were 0.44 to 0.47mmol/kg for mice and 0.62 to 0.64mmol/kg for rats. Sodium-metavanadate produced MDNF of 0.18 and 0.008mmol/kg mDAF of 0.36 and 1.00mmol/kg in mice and rats, respectively; LD50s were 0.29 to 0.30 for mice and 0.22 to 0.27mmol/kg for rats. Sodium-molybdate was 6 times less toxic than sodium-chromate and 3 to 4 times less toxic than sodium-tungstate. Sodium-metavanadate and sodium-chromate were equally toxic in rats and mice.","The comparative toxicity of sodium chromate, molybdate, tungstate and metavanadate: II. Experiments on rabbits Abs: The toxicities of sodium-chromate (7775113), sodium-molybdate (7631950), sodium-tungstate (11120017), and sodium-metavanadate (11105069) were investigated in Wistar-rats and Swiss-mice. The 24 hour maximum dose never fatal (MDNF) and minimum dose always fatal (mDAF) were determined, together with the median lethal dose (LD50), for each of the compounds. Clinical investigations of the symptomatology of intoxication were conducted. Experiments were performed using 2600 rats and 3000 mice. Symptomatology was similar in mice and rats during intoxication by each of the compounds. Animals given infra lethal doses of sodium-chromate showed no signs of poisoning; those treated with sodium-metavanadate showed signs of adynamia; and those given sodium-molybdate and sodium-tungstate showed prostration and a state of lethargy. Recuperation occurred in less than 1 hour after intoxication with sodium-molybdate, whereas there was a long coma and slow recovery in those given sodium-molybdate. Lethal doses given between MDNF and mDAF of the compounds produced the same poisoning syndrome; prostration after sodium-metavanadate was accompanied by some agitation. For sodium-chromate, the MDNF and mDAF were 0.13 and 0.34 millimoles per kilogram (mmol/kg), respectively, for mice and 0.20 and 0.75mmol/kg, respectively, for rats; LD50s were between 0.32 and 0.33mmol/kg for mice and between 0.375 and 0.37mmol/kg for rats. For sodium-molybdate, MDNF was 0.80mmol/kg for mice and 1.45mmol/kg for rats; mDAF was 1.85 and 3.50mmol/kg for mice and rats, respectively. LD50 ranged between 1.15 and 1.35mmol/kg for mice and 2.32 and 2.44mmol/kg for rats. For sodium-tungstate, MDNF was 0.30 and 0.20mmol/kg, and mDAF was 0.60 and 1.00mmol/kg for mice and rats, respectively. LD50s were 0.44 to 0.47mmol/kg for mice and 0.62 to 0.64mmol/kg for rats. Sodium-metavanadate produced MDNF of 0.18 and 0.008mmol/kg mDAF of 0.36 and 1.00mmol/kg in mice and rats, respectively; LD50s were 0.29 to 0.30 for mice and 0.22 to 0.27mmol/kg for rats. Sodium-molybdate was 6 times less toxic than sodium-chromate and 3 to 4 times less toxic than sodium-tungstate. Sodium-metavanadate and sodium-chromate were equally toxic in rats and mice."
903477,Jelmert et al. 1995,Cytogenetic studies of stainless steel welders using the tungsten inert gas and metal inert gas methods for welding,"BIOSIS COPYRIGHT: BIOL ABS. Cytogenetic damage was studied in lymphocytes from 23 welders using the Tungsten Inert Gas (TIG), and 21 welders using the Metal Inert Gas (MIG) and/or Metal Active Gas (MAG) methods on stainless steel (SS). A matched reference group I, and a larger reference group II of 94 subjects studied during the same time period, was established for comparison. Whole blood conventional cultures (CC), cultures in which DNA synthesis and repair were inhibited (IC), and the sister chromatid exchange (SCE) assay were applied in the study. For the CC a statistically significant decrease in chromosome breaks and cells with aberrations was found for both TIG and MIG/MAG/SS welders when compared with reference group II. A non-significant decrease was found for the corresponding parameters for the two groups of welders when compared with their matched referents. A statistically significant negative association was found between measurements of total chromium (Cr) in inhaled air and SCE, an","Cytogenetic studies of stainless steel welders using the tungsten inert gas and metal inert gas methods for welding Abs: BIOSIS COPYRIGHT: BIOL ABS. Cytogenetic damage was studied in lymphocytes from 23 welders using the Tungsten Inert Gas (TIG), and 21 welders using the Metal Inert Gas (MIG) and/or Metal Active Gas (MAG) methods on stainless steel (SS). A matched reference group I, and a larger reference group II of 94 subjects studied during the same time period, was established for comparison. Whole blood conventional cultures (CC), cultures in which DNA synthesis and repair were inhibited (IC), and the sister chromatid exchange (SCE) assay were applied in the study. For the CC a statistically significant decrease in chromosome breaks and cells with aberrations was found for both TIG and MIG/MAG/SS welders when compared with reference group II. A non-significant decrease was found for the corresponding parameters for the two groups of welders when compared with their matched referents. A statistically significant negative association was found between measurements of total chromium (Cr) in inhaled air and SCE, an"
900928,Zhang et al. 2008,"Immunolocalization of Kim-1, RPA-1, and RPA-2 in kidney of gentamicin-, mercury-, or chromium-treated rats: relationship to renal distributions of iNOS and nitrotyrosine","Immunohistochemical studies for kidney injury molecule-1 (Kim-1), renal papillary antigen-1 (RPA-1), and renal papillary antigen-2 (RPA-2) were conducted to explore their relationship to inducible nitric oxide synthase (iNOS) and nitrotyrosine expression. Male Sprague-Dawley rats were exposed to gentamicin (100 mg/kg/day Gen, sc, for 3 days), mercury (0.25 mg Hg/kg, iv, single dose), or chromium (5 mg Cr/kg, sc, single dose) and kidney tissue was examined 24 hours or 72 hours after the last dose of the nephrotoxicant. Another group of kidneys was evaluated 24 hours after rats were administered 3 daily doses (50, 100, 150, 200, or 300 mg/kg/day) of Gen. Gen- and Cr-treated rats exhibited increased immunoreactivity of Kim-1, RPA-1, and RPA-2 largely in the S1/S2 segments and to a lesser extent in the S3 segments of the proximal tubule of the kidney, whereas Hg-treated rats showed increased immunoreactivity of Kim-1, RPA-1, and RPA-2 in the S3 segments. Up-regulation of Kim-1, RPA-1, and RPA-2 expression correlated with injured tubular epithelial cells and also correlated with immunoreactivity of iNOS and nitrotyrosine. It is possible that iNOS activation with nitrotyrosine production in injured nephron segments may be involved in the induction of Kim-1, RPA-1, and RPA-2 following exposure to nephrotoxicants.","Immunolocalization of Kim-1, RPA-1, and RPA-2 in kidney of gentamicin-, mercury-, or chromium-treated rats: relationship to renal distributions of iNOS and nitrotyrosine Abs: Immunohistochemical studies for kidney injury molecule-1 (Kim-1), renal papillary antigen-1 (RPA-1), and renal papillary antigen-2 (RPA-2) were conducted to explore their relationship to inducible nitric oxide synthase (iNOS) and nitrotyrosine expression. Male Sprague-Dawley rats were exposed to gentamicin (100 mg/kg/day Gen, sc, for 3 days), mercury (0.25 mg Hg/kg, iv, single dose), or chromium (5 mg Cr/kg, sc, single dose) and kidney tissue was examined 24 hours or 72 hours after the last dose of the nephrotoxicant. Another group of kidneys was evaluated 24 hours after rats were administered 3 daily doses (50, 100, 150, 200, or 300 mg/kg/day) of Gen. Gen- and Cr-treated rats exhibited increased immunoreactivity of Kim-1, RPA-1, and RPA-2 largely in the S1/S2 segments and to a lesser extent in the S3 segments of the proximal tubule of the kidney, whereas Hg-treated rats showed increased immunoreactivity of Kim-1, RPA-1, and RPA-2 in the S3 segments. Up-regulation of Kim-1, RPA-1, and RPA-2 expression correlated with injured tubular epithelial cells and also correlated with immunoreactivity of iNOS and nitrotyrosine. It is possible that iNOS activation with nitrotyrosine production in injured nephron segments may be involved in the induction of Kim-1, RPA-1, and RPA-2 following exposure to nephrotoxicants."
900789,Tonietto et al. 2010,"Simultaneous speciation of arsenic (As(III), MMA, DMA, and As(V)) and selenium (Se(IV), Se(VI), and SeCN-) in petroleum refinery aqueous streams","High-performance liquid chromatography (HPLC) coupled to an ICP-MS with an octapole reaction system (ORS) has been used to carry out quantitative speciation of selenium (Se) and arsenic (As) in the stream waters of a refining process. The argon dimers interfering with the (78)Se and (80)Se isotopes were suppressed by pressurizing the octapole chamber with 3.1 mL min(-1) H(2) and 0.5 mL min(-1) He. Four arsenic species arsenite--As(III), arsenate (As(V)), monomethylarsonic acid (MMA), and dimethylarsinic acid (DMA)--and three inorganic Se species--selenite Se(IV), selenate Se(VI), and selenocyanate (SeCN(-))--were separated in a single run by ion chromatography (IC) using gradient elution with 100 mmol L(-1) NH(4)NO(3), pH 8.5, adjusted by addition of NH(3), as eluent. Repeatabilities of peak position and of peak area evaluation were better than 1% and about 3%, respectively. Detection limits (as 3sigma of the baseline noise) were 81, 56, and 75 ng L(-1) for Se(IV), Se(VI), and SeCN(-), respectively, and 22, 19, 25, and 16 ng L(-1) for As(III), As(V), MMA, and DMA, respectively. Calibration curve R (2) values ranged between 0.996 and 0.999 for the arsenic and selenium species. Column recovery for ion chromatography was calculated to be 97 +/- 6% for combined arsenic species and 98 +/- 3% for combined selenium species. Because certified reference materials for As and Se speciation studies are still not commercially available, in order to check accuracy and precision the method was applied to certified reference materials, BCR 714, BCR 1714, and BCR 715 and to two different refinery samples--inlet and outlet wastewater. The method was successfully used to study the quantitative speciation of selenium and arsenic in petroleum refinery wastewaters.","Simultaneous speciation of arsenic (As(III), MMA, DMA, and As(V)) and selenium (Se(IV), Se(VI), and SeCN-) in petroleum refinery aqueous streams Abs: High-performance liquid chromatography (HPLC) coupled to an ICP-MS with an octapole reaction system (ORS) has been used to carry out quantitative speciation of selenium (Se) and arsenic (As) in the stream waters of a refining process. The argon dimers interfering with the (78)Se and (80)Se isotopes were suppressed by pressurizing the octapole chamber with 3.1 mL min(-1) H(2) and 0.5 mL min(-1) He. Four arsenic species arsenite--As(III), arsenate (As(V)), monomethylarsonic acid (MMA), and dimethylarsinic acid (DMA)--and three inorganic Se species--selenite Se(IV), selenate Se(VI), and selenocyanate (SeCN(-))--were separated in a single run by ion chromatography (IC) using gradient elution with 100 mmol L(-1) NH(4)NO(3), pH 8.5, adjusted by addition of NH(3), as eluent. Repeatabilities of peak position and of peak area evaluation were better than 1% and about 3%, respectively. Detection limits (as 3sigma of the baseline noise) were 81, 56, and 75 ng L(-1) for Se(IV), Se(VI), and SeCN(-), respectively, and 22, 19, 25, and 16 ng L(-1) for As(III), As(V), MMA, and DMA, respectively. Calibration curve R (2) values ranged between 0.996 and 0.999 for the arsenic and selenium species. Column recovery for ion chromatography was calculated to be 97 +/- 6% for combined arsenic species and 98 +/- 3% for combined selenium species. Because certified reference materials for As and Se speciation studies are still not commercially available, in order to check accuracy and precision the method was applied to certified reference materials, BCR 714, BCR 1714, and BCR 715 and to two different refinery samples--inlet and outlet wastewater. The method was successfully used to study the quantitative speciation of selenium and arsenic in petroleum refinery wastewaters."
900777,Tinjum et al. 2008,Mobilization of Cr(VI) from chromite ore processing residue through acid treatment,"Batch leaching studies on chromite ore processing residue (COPR) were performed using acids to investigate leaching of hexavalent chromium, Cr(VI), with respect to particle size, reaction time, and type of acid (HNO(3) and H(2)SO(4)). Aqueous Cr(VI) is maximized at approximately 0.04 mol Cr(VI) per kg of dry COPR at pH 7.6-8.1. Cr(VI) mobilized more slowly for larger particles, and the pH increased with time and increased more rapidly for smaller particles, suggesting that rate limitations occur in the solid phase. With H(2)SO(4), the pH stabilized at a higher value (8.8 for H(2)SO(4) vs. 8.0 for HNO(3)) and more rapidly (16 h vs. 30 h), and the differences in pH for different particle sizes were smaller. The acid neutralization capacity (ANC) of COPR is very large (8 mol HNO(3) per kg of dry COPR for a stable eluate pH of 7.5). Changes to the elemental and mineralogical composition and distribution in COPR particles after mixing with acid indicate that Cr(VI)-bearing solids dissolved. However, concentrations of Cr(VI) &gt;2800 mg kg(-1) (&gt;50% of the pre-treatment concentration) were still found after mixing with acid, regardless of the particle size, reaction time, or type of acid used. The residual Cr(VI) appears to be partially associated with poorly-ordered Fe and Al oxyhydroxides that precipitated in the interstitial areas of COPR particles. Remediation strategies that use HNO(3) or H(2)SO(4) to neutralize COPR or to maximize Cr(VI) in solution are likely to require extensive amounts of acid, may not mobilize all of the Cr(VI), and may require extended contact time, even under well-mixed conditions.","Mobilization of Cr(VI) from chromite ore processing residue through acid treatment Abs: Batch leaching studies on chromite ore processing residue (COPR) were performed using acids to investigate leaching of hexavalent chromium, Cr(VI), with respect to particle size, reaction time, and type of acid (HNO(3) and H(2)SO(4)). Aqueous Cr(VI) is maximized at approximately 0.04 mol Cr(VI) per kg of dry COPR at pH 7.6-8.1. Cr(VI) mobilized more slowly for larger particles, and the pH increased with time and increased more rapidly for smaller particles, suggesting that rate limitations occur in the solid phase. With H(2)SO(4), the pH stabilized at a higher value (8.8 for H(2)SO(4) vs. 8.0 for HNO(3)) and more rapidly (16 h vs. 30 h), and the differences in pH for different particle sizes were smaller. The acid neutralization capacity (ANC) of COPR is very large (8 mol HNO(3) per kg of dry COPR for a stable eluate pH of 7.5). Changes to the elemental and mineralogical composition and distribution in COPR particles after mixing with acid indicate that Cr(VI)-bearing solids dissolved. However, concentrations of Cr(VI) &gt;2800 mg kg(-1) (&gt;50% of the pre-treatment concentration) were still found after mixing with acid, regardless of the particle size, reaction time, or type of acid used. The residual Cr(VI) appears to be partially associated with poorly-ordered Fe and Al oxyhydroxides that precipitated in the interstitial areas of COPR particles. Remediation strategies that use HNO(3) or H(2)SO(4) to neutralize COPR or to maximize Cr(VI) in solution are likely to require extensive amounts of acid, may not mobilize all of the Cr(VI), and may require extended contact time, even under well-mixed conditions."
898753,Wang et al. 2011,Synthesis and structure of a bismuth(III)/chromium(VI) oxo cluster containing a Bi4Cr4O12 core,"Bismuth(III) compounds containing the Kläui's oxygen tripodal ligand [CpCo{P(O)(OEt)(2)}(3)](-) (L(OEt)(-)) have been synthesized, and their interactions with dichromate in aqueous media were studied. The treatment of Bi(5)O(OH)(9)(NO(3))(4) with NaL(OEt) in water afforded [L(OEt)Bi(NO(3))(2)](2) (1), whereas that of BiCl(3) with NaL(OEt) in CH(2)Cl(2) yielded L(OEt)BiCl(2) (2). Chloride abstraction of 2 with AgX afforded [L(OEt)BiX(2)](2) [X(-) = triflate (OTf(-)) (3), tosylate (OTs(-)) (4)]. In aqueous solutions at pH &gt; 4, 4 underwent ligand redistribution to give the bis(tripod) complex [(L(OEt))(2)Bi(H(2)O)][OTs] (5). The treatment of 4 with Na(2)Cr(2)O(7) in acetone/water afforded the Bi(III)/Cr(VI) oxo cluster [(L(OEt))(4)Bi(4)(?(3)-CrO(4))(2)(?(3)-Cr(2)O(7))(2)] (6) containing a unique Bi(4)Cr(4)O(12) oxometallic core. Compound 6 oxidized benzyl alcohol to give ca. 6 equiv of benzaldehyde. The reaction between 2 and CrO(3) yielded [L(OEt)Bi(OCrO(2)Cl)](2)(?-Cl)(2) (7). The crystal structures of complexes 4-7 have been determined.","Synthesis and structure of a bismuth(III)/chromium(VI) oxo cluster containing a Bi4Cr4O12 core Abs: Bismuth(III) compounds containing the Kläui's oxygen tripodal ligand [CpCo{P(O)(OEt)(2)}(3)](-) (L(OEt)(-)) have been synthesized, and their interactions with dichromate in aqueous media were studied. The treatment of Bi(5)O(OH)(9)(NO(3))(4) with NaL(OEt) in water afforded [L(OEt)Bi(NO(3))(2)](2) (1), whereas that of BiCl(3) with NaL(OEt) in CH(2)Cl(2) yielded L(OEt)BiCl(2) (2). Chloride abstraction of 2 with AgX afforded [L(OEt)BiX(2)](2) [X(-) = triflate (OTf(-)) (3), tosylate (OTs(-)) (4)]. In aqueous solutions at pH &gt; 4, 4 underwent ligand redistribution to give the bis(tripod) complex [(L(OEt))(2)Bi(H(2)O)][OTs] (5). The treatment of 4 with Na(2)Cr(2)O(7) in acetone/water afforded the Bi(III)/Cr(VI) oxo cluster [(L(OEt))(4)Bi(4)(?(3)-CrO(4))(2)(?(3)-Cr(2)O(7))(2)] (6) containing a unique Bi(4)Cr(4)O(12) oxometallic core. Compound 6 oxidized benzyl alcohol to give ca. 6 equiv of benzaldehyde. The reaction between 2 and CrO(3) yielded [L(OEt)Bi(OCrO(2)Cl)](2)(?-Cl)(2) (7). The crystal structures of complexes 4-7 have been determined."
897999,Sheha and  El-Zahhar 2008,Synthesis of some ferromagnetic composite resins and their metal removal characteristics in aqueous solutions,"In this study, a procedure for synthesis of new organic-inorganic magnetic composite resins was established. The procedure was based upon immobilization of magnetite (Mag) as a ferromagnetic material within the polymer poly(acrylic acid acrylonitrile) P(AA-AN) and the ion exchange resin (Amberlite IR 120). The produced magnetic resins, IR 120-PAN-Mag (R1) and P(AA-AN)-Mag (R2) were assessed as sorbents for Cr(VI). Various factors influencing the sorption of Cr(VI), e.g., pH, equilibrium time, initial concentration and temperature were studied. The sorption process was very fast initially and maximum sorption was achieved within 3h and pH 5.1. The kinetic of the system has been evaluated with pseudo first order model, second order model, Elovich model, intra-particle diffusion model and liquid film diffusion model. Chromium interaction with composite particles followed second-order kinetics with a correlation coefficient extremely high and closer to unity and rate constant (k(s)) has the values 1.68 x 10(-4) and 1.9 x 10(-4)g(mg(-1)min(-1)) for R1 and R2, respectively. The values of equilibrium sorption capacity (q(e)) are consistent with the modeled data and attain the range 893-951 mg g(-1). Kinetically, both pore diffusion and film diffusion are participating in ruling the diffusion of Cr(VI) ions. The sorption data gave good fits with Temkin and Flory-Huggins isotherm models. The isotherm parameters related to the heat of sorption are in the range 8-16 kJ mol(-1) which is the range of bonding energy for ion exchange interactions and so suggest an ion exchange mechanism for removal of Cr(VI) by the composite sorbents. The adsorption process was exothermic with DeltaH in the range of -73 to -97 kJ mol(-1). The negative values of Gibbs free energy confirm the feasibility and the spontaneous nature of Cr(VI) removal with these novel composites.","Synthesis of some ferromagnetic composite resins and their metal removal characteristics in aqueous solutions Abs: In this study, a procedure for synthesis of new organic-inorganic magnetic composite resins was established. The procedure was based upon immobilization of magnetite (Mag) as a ferromagnetic material within the polymer poly(acrylic acid acrylonitrile) P(AA-AN) and the ion exchange resin (Amberlite IR 120). The produced magnetic resins, IR 120-PAN-Mag (R1) and P(AA-AN)-Mag (R2) were assessed as sorbents for Cr(VI). Various factors influencing the sorption of Cr(VI), e.g., pH, equilibrium time, initial concentration and temperature were studied. The sorption process was very fast initially and maximum sorption was achieved within 3h and pH 5.1. The kinetic of the system has been evaluated with pseudo first order model, second order model, Elovich model, intra-particle diffusion model and liquid film diffusion model. Chromium interaction with composite particles followed second-order kinetics with a correlation coefficient extremely high and closer to unity and rate constant (k(s)) has the values 1.68 x 10(-4) and 1.9 x 10(-4)g(mg(-1)min(-1)) for R1 and R2, respectively. The values of equilibrium sorption capacity (q(e)) are consistent with the modeled data and attain the range 893-951 mg g(-1). Kinetically, both pore diffusion and film diffusion are participating in ruling the diffusion of Cr(VI) ions. The sorption data gave good fits with Temkin and Flory-Huggins isotherm models. The isotherm parameters related to the heat of sorption are in the range 8-16 kJ mol(-1) which is the range of bonding energy for ion exchange interactions and so suggest an ion exchange mechanism for removal of Cr(VI) by the composite sorbents. The adsorption process was exothermic with DeltaH in the range of -73 to -97 kJ mol(-1). The negative values of Gibbs free energy confirm the feasibility and the spontaneous nature of Cr(VI) removal with these novel composites."
897463,Shifu et al. 2008,Preparation and activity evaluation of p-n junction photocatalyst NiO/TiO2,"p-n Junction photocatalyst NiO/TiO2 was prepared by sol-gel method using Ni(NO3)2.6H2O and tetrabutyl titanate [Ti(OC4H9)4] as the raw materials. The p-n junction photocatalyst NiO/TiO2 was characterized by UV-vis diffuse reflection spectrum, X-ray powder diffraction (XRD) and X-ray photoelectron spectroscopy (XPS). The photocatalytic activity of the photocatalyst was evaluated by photocatalytic reduction of Cr2O7(2-) and photocatalytic oxidation of rhodamine B. The results show that, for photocatalytic reduction of Cr2O7(2-), the optimum percentage of doped-NiO is 0.5% (mole ratio of Ni/Ti). The photocatalytic activity of the p-n junction NiO/TiO2 is much higher than that of TiO2 on the photocatalytic reduction of Cr2O7(2-). However, the photocatalytic activity of the p-n junction photocatalyst NiO/TiO2 is much lower than that of TiO2 on the photocatalytic oxidation of rhodamine B. Namely, the p-n junction photocatalyst NiO/TiO2 has higher photocatalytic reduction activity, but lower photocatalytic oxidation activity. Effects of heat treatment on the photocatalytic activity of p-n junction photocatalyst NiO/TiO2 were investigated. The mechanisms of influence on the photocatalytic activity were also discussed by the p-n junction principle.","Preparation and activity evaluation of p-n junction photocatalyst NiO/TiO2 Abs: p-n Junction photocatalyst NiO/TiO2 was prepared by sol-gel method using Ni(NO3)2.6H2O and tetrabutyl titanate [Ti(OC4H9)4] as the raw materials. The p-n junction photocatalyst NiO/TiO2 was characterized by UV-vis diffuse reflection spectrum, X-ray powder diffraction (XRD) and X-ray photoelectron spectroscopy (XPS). The photocatalytic activity of the photocatalyst was evaluated by photocatalytic reduction of Cr2O7(2-) and photocatalytic oxidation of rhodamine B. The results show that, for photocatalytic reduction of Cr2O7(2-), the optimum percentage of doped-NiO is 0.5% (mole ratio of Ni/Ti). The photocatalytic activity of the p-n junction NiO/TiO2 is much higher than that of TiO2 on the photocatalytic reduction of Cr2O7(2-). However, the photocatalytic activity of the p-n junction photocatalyst NiO/TiO2 is much lower than that of TiO2 on the photocatalytic oxidation of rhodamine B. Namely, the p-n junction photocatalyst NiO/TiO2 has higher photocatalytic reduction activity, but lower photocatalytic oxidation activity. Effects of heat treatment on the photocatalytic activity of p-n junction photocatalyst NiO/TiO2 were investigated. The mechanisms of influence on the photocatalytic activity were also discussed by the p-n junction principle."
896579,Staniek et al. 2010,Genotoxicity assessment of chromium(III) propionate complex in the rat model using the comet assay,"The aim of the study was to assess genotoxicity of a chromium(III) propionate complex in rat's peripheral blood lymphocytes by the comet assay. The study was carried out on 18 12-weeks old female Wistar rats that were divided into three equal groups (six animals each): control (0), control-Cr(VI) and Cr(III)-tested rat fed ad libitum a basal diet and the diet supplemented either with 10 mg Cr(VI)/kg diet (given as K(2)Cr(2)O(7), equivalent of 1mg/kg body mass/day) or 1000 mg Cr(III)/kg diet (given as [Cr(3)O(O(2)CCH(2)CH(3))6(H(2)O)(3)]NO(3)), equivalent of 100mg Cr/kg body mass/day) for 4 weeks. High doses of supplementary Cr(III) were found to not affect body mass gain, feeding efficiency ratio and internal organ masses. Treatment of rats with the Cr(III) propionate complex, in contrast to Cr(VI), did not affect significantly the comet assay results in lymphocytes, which suggests that the compound does not exert genotoxic effects in rats.","Genotoxicity assessment of chromium(III) propionate complex in the rat model using the comet assay Abs: The aim of the study was to assess genotoxicity of a chromium(III) propionate complex in rat's peripheral blood lymphocytes by the comet assay. The study was carried out on 18 12-weeks old female Wistar rats that were divided into three equal groups (six animals each): control (0), control-Cr(VI) and Cr(III)-tested rat fed ad libitum a basal diet and the diet supplemented either with 10 mg Cr(VI)/kg diet (given as K(2)Cr(2)O(7), equivalent of 1mg/kg body mass/day) or 1000 mg Cr(III)/kg diet (given as [Cr(3)O(O(2)CCH(2)CH(3))6(H(2)O)(3)]NO(3)), equivalent of 100mg Cr/kg body mass/day) for 4 weeks. High doses of supplementary Cr(III) were found to not affect body mass gain, feeding efficiency ratio and internal organ masses. Treatment of rats with the Cr(III) propionate complex, in contrast to Cr(VI), did not affect significantly the comet assay results in lymphocytes, which suggests that the compound does not exert genotoxic effects in rats."
896336,Soudani et al. 2011,Nephrotoxicity induced by chromium (VI) in adult rats and their progeny,"To assess kidney damages in pregnant and lactating rats and in their suckling pups, Wistar female rats were given, through drinking water, 700 parts per million (ppm) of K(2)Cr(2)O(7) from the 14th day of pregnancy until day 14 after delivery. Toxicity was objectified by a significant increase in malondialdehyde (MDA), glutathione (GSH) and nitric oxide (NO) levels in kidney of chromium-treated mothers and their suckling pups. Moreover, lactate dehydrogenase (LDH) was increased in kidney and decreased in plasma of K(2)Cr(2)O(7)-treated rats. Activities of superoxide dismutase (SOD), catalase (CAT) and glutathione peroxidase (GPx) were increased in dams and decreased in their pups. Interestingly, these biochemical modifications were accompanied by higher plasma and lower urinary levels of creatinine, a specific indicator of glomerular function, and of urea than those of controls. Significant increase in creatinine clearance was also found in treated mothers and in their progeny. Histological studies showed an infiltration of mononuclear cells, necrosis and vascular congestion in kidney of pups and dams. Based on the present findings, K(2)Cr(2)O(7) administrated to female rats during late pregnancy and early postnatal periods provoked kidney damages in dams and their offspring.","Nephrotoxicity induced by chromium (VI) in adult rats and their progeny Abs: To assess kidney damages in pregnant and lactating rats and in their suckling pups, Wistar female rats were given, through drinking water, 700 parts per million (ppm) of K(2)Cr(2)O(7) from the 14th day of pregnancy until day 14 after delivery. Toxicity was objectified by a significant increase in malondialdehyde (MDA), glutathione (GSH) and nitric oxide (NO) levels in kidney of chromium-treated mothers and their suckling pups. Moreover, lactate dehydrogenase (LDH) was increased in kidney and decreased in plasma of K(2)Cr(2)O(7)-treated rats. Activities of superoxide dismutase (SOD), catalase (CAT) and glutathione peroxidase (GPx) were increased in dams and decreased in their pups. Interestingly, these biochemical modifications were accompanied by higher plasma and lower urinary levels of creatinine, a specific indicator of glomerular function, and of urea than those of controls. Significant increase in creatinine clearance was also found in treated mothers and in their progeny. Histological studies showed an infiltration of mononuclear cells, necrosis and vascular congestion in kidney of pups and dams. Based on the present findings, K(2)Cr(2)O(7) administrated to female rats during late pregnancy and early postnatal periods provoked kidney damages in dams and their offspring."
888103,Myers et al. 2011,The intracellular redox stress caused by hexavalent chromium is selective for proteins that have key roles in cell survival and thiol redox control,"Hexavalent chromium [Cr(VI)] compounds (e.g. chromates) are strong oxidants that readily enter cells where they are reduced to reactive Cr intermediates that can directly oxidize some cell components and can promote the generation of reactive oxygen and nitrogen species. Inhalation is a major route of exposure which directly exposes the bronchial epithelium. Previous studies with non-cancerous human bronchial epithelial cells (BEAS-2B) demonstrated that Cr(VI) treatment results in the irreversible inhibition of thioredoxin reductase (TrxR) and the oxidation of thioredoxins (Trx) and peroxiredoxins (Prx). The mitochondrial Trx/Prx system is somewhat more sensitive to Cr(VI) than the cytosolic Trx/Prx system, and other redox-sensitive mitochondrial functions are subsequently affected including electron transport complexes I and II. Studies reported here show that Cr(VI) does not cause indiscriminant thiol oxidation, and that the Trx/Prx system is among the most sensitive of cellular protein thiols. Trx/Prx oxidation is not unique to BEAS-2B cells, as it was also observed in primary human bronchial epithelial cells. Increasing the intracellular levels of ascorbate, an endogenous Cr(VI) reductant, did not alter the effects on TrxR, Trx, or Prx. The peroxynitrite scavenger MnTBAP did not protect TrxR, Trx, Prx, or the electron transport chain from the effects of Cr(VI), implying that peroxynitrite is not required for these effects. Nitration of tyrosine residues of TrxR was not observed following Cr(VI) treatment, further ruling out peroxynitrite as a significant contributor to the irreversible inhibition of TrxR. Cr(VI) treatments that disrupt the TrxR/Trx/Prx system did not cause detectable mitochondrial DNA damage. Overall, the redox stress that results from Cr(VI) exposure shows selectivity for key proteins which are known to be important for redox signaling, antioxidant defense, and cell survival.","The intracellular redox stress caused by hexavalent chromium is selective for proteins that have key roles in cell survival and thiol redox control Abs: Hexavalent chromium [Cr(VI)] compounds (e.g. chromates) are strong oxidants that readily enter cells where they are reduced to reactive Cr intermediates that can directly oxidize some cell components and can promote the generation of reactive oxygen and nitrogen species. Inhalation is a major route of exposure which directly exposes the bronchial epithelium. Previous studies with non-cancerous human bronchial epithelial cells (BEAS-2B) demonstrated that Cr(VI) treatment results in the irreversible inhibition of thioredoxin reductase (TrxR) and the oxidation of thioredoxins (Trx) and peroxiredoxins (Prx). The mitochondrial Trx/Prx system is somewhat more sensitive to Cr(VI) than the cytosolic Trx/Prx system, and other redox-sensitive mitochondrial functions are subsequently affected including electron transport complexes I and II. Studies reported here show that Cr(VI) does not cause indiscriminant thiol oxidation, and that the Trx/Prx system is among the most sensitive of cellular protein thiols. Trx/Prx oxidation is not unique to BEAS-2B cells, as it was also observed in primary human bronchial epithelial cells. Increasing the intracellular levels of ascorbate, an endogenous Cr(VI) reductant, did not alter the effects on TrxR, Trx, or Prx. The peroxynitrite scavenger MnTBAP did not protect TrxR, Trx, Prx, or the electron transport chain from the effects of Cr(VI), implying that peroxynitrite is not required for these effects. Nitration of tyrosine residues of TrxR was not observed following Cr(VI) treatment, further ruling out peroxynitrite as a significant contributor to the irreversible inhibition of TrxR. Cr(VI) treatments that disrupt the TrxR/Trx/Prx system did not cause detectable mitochondrial DNA damage. Overall, the redox stress that results from Cr(VI) exposure shows selectivity for key proteins which are known to be important for redox signaling, antioxidant defense, and cell survival."
868291,Ahmad et al. 2011,"Cr(VI) Induces Lipid Peroxidation, Protein Oxidation and Alters the Activities of Antioxidant Enzymes in Human Erythrocytes","The effect of potassium dichromate (K(2)Cr(2)O(7)), a hexavalent chromium compound, on human erythrocytes was studied under in vitro conditions. Incubation of erythrocytes with different concentrations of K(2)Cr(2)O(7) resulted in marked hemolysis in a concentration-dependent manner. K(2)Cr(2)O(7) treatment also caused significant increase in protein oxidation, lipid peroxidation and decrease in total sulfhydryl content, indicating that it causes oxidative stress in human erythrocytes. However, there was no concomitant nitrosative stress as the nitric oxide levels in hemolysates from K(2)Cr(2)O(7)-treated erythrocytes were lower than in control. Exposure of erythrocytes to K(2)Cr(2)O(7) decreased the activities of catalase, glutathione peroxidase, thioredoxin reductase, glucose-6-phosphate dehydrogenase, and glutathione reductase, whereas the activities of Cu-Zn superoxide dismutase and glutathione S-transferase were increased. These results show that K(2)Cr(2)O(7) induces oxidative stress and alters the antioxidant defense mechanism of human erythrocytes.","Cr(VI) Induces Lipid Peroxidation, Protein Oxidation and Alters the Activities of Antioxidant Enzymes in Human Erythrocytes Abs: The effect of potassium dichromate (K(2)Cr(2)O(7)), a hexavalent chromium compound, on human erythrocytes was studied under in vitro conditions. Incubation of erythrocytes with different concentrations of K(2)Cr(2)O(7) resulted in marked hemolysis in a concentration-dependent manner. K(2)Cr(2)O(7) treatment also caused significant increase in protein oxidation, lipid peroxidation and decrease in total sulfhydryl content, indicating that it causes oxidative stress in human erythrocytes. However, there was no concomitant nitrosative stress as the nitric oxide levels in hemolysates from K(2)Cr(2)O(7)-treated erythrocytes were lower than in control. Exposure of erythrocytes to K(2)Cr(2)O(7) decreased the activities of catalase, glutathione peroxidase, thioredoxin reductase, glucose-6-phosphate dehydrogenase, and glutathione reductase, whereas the activities of Cu-Zn superoxide dismutase and glutathione S-transferase were increased. These results show that K(2)Cr(2)O(7) induces oxidative stress and alters the antioxidant defense mechanism of human erythrocytes."
865788,Ostrowski et al. 2011,"Photochemistry of trans-Cr(cyclam)(ONO)2+, a nitric oxide precursor","Experimental and density functional theory (DFT) studies are described that are focused on outlining the reactivity of the known photochemical nitric oxide precursor trans-Cr(cyclam)(ONO)(2)(+) (&quot;CrONO&quot;, cyclam = 1,4,8,11-tetrazacycltetradecane). Studies in both aerated and deaerated aqueous media are described as are the roles of both the oxidant O(2) and a reductant such as glutathione in trapping the apparent Cr(IV) photoreaction intermediate trans-Cr(cyclam)(O)(ONO)(+). Also reported and characterized structurally is the Cr(V) product of long-term photolysis in the absence of reducing agents, the trans-dioxo species [trans-Cr(cyclam)(O)(2)](ClO(4)). Photosensitization experiments indicate that at least a significant fraction of the reaction occurs from the lowest energy doublet excited state(s). Lastly, cell culture experiments demonstrate that CrONO has little or no acute toxicity either before or after photolysis.","Photochemistry of trans-Cr(cyclam)(ONO)2+, a nitric oxide precursor Abs: Experimental and density functional theory (DFT) studies are described that are focused on outlining the reactivity of the known photochemical nitric oxide precursor trans-Cr(cyclam)(ONO)(2)(+) (&quot;CrONO&quot;, cyclam = 1,4,8,11-tetrazacycltetradecane). Studies in both aerated and deaerated aqueous media are described as are the roles of both the oxidant O(2) and a reductant such as glutathione in trapping the apparent Cr(IV) photoreaction intermediate trans-Cr(cyclam)(O)(ONO)(+). Also reported and characterized structurally is the Cr(V) product of long-term photolysis in the absence of reducing agents, the trans-dioxo species [trans-Cr(cyclam)(O)(2)](ClO(4)). Photosensitization experiments indicate that at least a significant fraction of the reaction occurs from the lowest energy doublet excited state(s). Lastly, cell culture experiments demonstrate that CrONO has little or no acute toxicity either before or after photolysis."
864259,Lacroix-Fralish et al. 2009,A centrifugal microanalysis system for the determination of nitrite and hexavalent chromium,"A centrifugal microanalysis system using spectrophotometric detection has been developed for the determination of nitrite and chromium VI. The system was designed to illustrate the potential of centrifugal microfluidic systems for on-site (field) analysis of waters. The performance was significantly better than manual/visual field test systems and approaches that of bench top systems with detection limits of 0.008 mg L(-1) NO(2)(-)-N and 0.03 mg L(-1) Cr(6+). The system used pre-loaded solid reagents on the disc, providing ease of use, and could process up to 24 samples simultaneously. Precision was enhanced by the use of a multiwavelength ratiometric blank estimation technique.","A centrifugal microanalysis system for the determination of nitrite and hexavalent chromium Abs: A centrifugal microanalysis system using spectrophotometric detection has been developed for the determination of nitrite and chromium VI. The system was designed to illustrate the potential of centrifugal microfluidic systems for on-site (field) analysis of waters. The performance was significantly better than manual/visual field test systems and approaches that of bench top systems with detection limits of 0.008 mg L(-1) NO(2)(-)-N and 0.03 mg L(-1) Cr(6+). The system used pre-loaded solid reagents on the disc, providing ease of use, and could process up to 24 samples simultaneously. Precision was enhanced by the use of a multiwavelength ratiometric blank estimation technique."
864086,Lv et al. 2011,Removal of chromium(VI) from wastewater by nanoscale zero-valent iron particles supported on multiwalled carbon nanotubes,"For the first time, nanoscale zero-valent iron (nZVI)-multiwalled carbon nanotube (MWCNT) nanocomposites were adopted to remove Cr(VI) from wastewater. Such composites were prepared through depositing nZVI particles onto MWCNTs by in situ reduction of ferrous sulfate and then characterized by TEM, SEM and XRD. The results showed that nZVI particles could disperse on the surface or into the network of MWCNTs. Compared to bare nZVI or nZVI-activated carbon composites, the nZVI-MWCNT nanocomposites exhibited around 36% higher efficiency on Cr(VI) removal. The mass ratio of nZVI to MWCNTs was optimized at 1:2, at ionic strength of 0.05M NaCl. The reaction followed a pseudo first-order model under different initial Cr(VI) concentrations and pHs. Low pH and initial Cr(VI) concentration could increase both removal efficiency and rate constants. Anions, such as SO(4)(2-), NO(3)(-) and HCO(3)(-), exhibited negative effects on the removal of Cr(VI), while the effects of PO(4)(3-) and SiO(3)(2-) were insignificant. Overall, nZVI-MWCNT nanocomposites offer a promising alternative material for the removal of Cr(VI) ions from wastewater.","Removal of chromium(VI) from wastewater by nanoscale zero-valent iron particles supported on multiwalled carbon nanotubes Abs: For the first time, nanoscale zero-valent iron (nZVI)-multiwalled carbon nanotube (MWCNT) nanocomposites were adopted to remove Cr(VI) from wastewater. Such composites were prepared through depositing nZVI particles onto MWCNTs by in situ reduction of ferrous sulfate and then characterized by TEM, SEM and XRD. The results showed that nZVI particles could disperse on the surface or into the network of MWCNTs. Compared to bare nZVI or nZVI-activated carbon composites, the nZVI-MWCNT nanocomposites exhibited around 36% higher efficiency on Cr(VI) removal. The mass ratio of nZVI to MWCNTs was optimized at 1:2, at ionic strength of 0.05M NaCl. The reaction followed a pseudo first-order model under different initial Cr(VI) concentrations and pHs. Low pH and initial Cr(VI) concentration could increase both removal efficiency and rate constants. Anions, such as SO(4)(2-), NO(3)(-) and HCO(3)(-), exhibited negative effects on the removal of Cr(VI), while the effects of PO(4)(3-) and SiO(3)(2-) were insignificant. Overall, nZVI-MWCNT nanocomposites offer a promising alternative material for the removal of Cr(VI) ions from wastewater."
861534,Faybishenko et al. 2008,In situ long-term reductive bioimmobilization of Cr(VI) in groundwater using hydrogen release compound,"The results of a field experiment designed to test the effectiveness of a novel approach for long-term, in situ bioimmobilization of toxic and soluble Cr(VI) in groundwater using a hydrogen release compound (HRC)--a slow release glycerol polylactate--are described. The field experiment was conducted at the Hanford Site (Washington), a U.S. Department of Energy nuclear production facility, using a combination of hydrogeological, geophysical, geochemical, and microbiological measurements and analyses of water samples and sediments. The results of this experiment show that a single HRC injection into groundwater stimulates an increase in biomass, a depletion of terminal electron acceptors O2, NO3-, and SO4(2-), and an increase in Fe2+, resulting in a significant decrease in soluble Cr(VI). The Cr(VI) concentration has remained below the background concentration in the downgradient pumping/ monitoring well, and below the detection limit in the injection well for more than 3 years after the HRC injection. The degree of sustainability of Cr(VI) reductive bioimmobilization under different redox conditions at this and other contaminated sites is currently under study.","In situ long-term reductive bioimmobilization of Cr(VI) in groundwater using hydrogen release compound Abs: The results of a field experiment designed to test the effectiveness of a novel approach for long-term, in situ bioimmobilization of toxic and soluble Cr(VI) in groundwater using a hydrogen release compound (HRC)--a slow release glycerol polylactate--are described. The field experiment was conducted at the Hanford Site (Washington), a U.S. Department of Energy nuclear production facility, using a combination of hydrogeological, geophysical, geochemical, and microbiological measurements and analyses of water samples and sediments. The results of this experiment show that a single HRC injection into groundwater stimulates an increase in biomass, a depletion of terminal electron acceptors O2, NO3-, and SO4(2-), and an increase in Fe2+, resulting in a significant decrease in soluble Cr(VI). The Cr(VI) concentration has remained below the background concentration in the downgradient pumping/ monitoring well, and below the detection limit in the injection well for more than 3 years after the HRC injection. The degree of sustainability of Cr(VI) reductive bioimmobilization under different redox conditions at this and other contaminated sites is currently under study."
855298,Bartyzel and  Cukrowska 2011,"Solid phase extraction method for the separation and determination of chromium(III) in the presence of chromium(VI) using silica gel modified by N,N'-bis-(?-methylsalicylidene)-2,2-dimethyl-1,3-propanediimine","N,N'-bis-(?-methylsalicylidene)-2,2-dimethyl-1,3-propanediimine (SBTD) modified silica gel was prepared and used as sorbent for solid phase extraction of Cr(III) ions from aqueous solution. This sorbent showed a high sorption affinity for Cr(III) while recovery of Cr(VI) was very low. The analyte ion retained on the column was eluted with 1 mol L(-1) HNO(3). The chromium ion in the eluent was determined by graphite furnace atomic absorption spectrometry. The effects of different parameters such as pH, eluent type and volume, Schiff's base concentration, sample and eluent flow rate, interfering ions and adsorbent amount were investigated.","Solid phase extraction method for the separation and determination of chromium(III) in the presence of chromium(VI) using silica gel modified by N,N'-bis-(?-methylsalicylidene)-2,2-dimethyl-1,3-propanediimine Abs: N,N'-bis-(?-methylsalicylidene)-2,2-dimethyl-1,3-propanediimine (SBTD) modified silica gel was prepared and used as sorbent for solid phase extraction of Cr(III) ions from aqueous solution. This sorbent showed a high sorption affinity for Cr(III) while recovery of Cr(VI) was very low. The analyte ion retained on the column was eluted with 1 mol L(-1) HNO(3). The chromium ion in the eluent was determined by graphite furnace atomic absorption spectrometry. The effects of different parameters such as pH, eluent type and volume, Schiff's base concentration, sample and eluent flow rate, interfering ions and adsorbent amount were investigated."
846402,Wang et al. 2011,NADPH oxidase activation is required in reactive oxygen species generation and cell transformation induced by hexavalent chromium,"Hexavalent chromium [Cr(VI)] is a well-known human carcinogen associated with the incidence of lung cancer. Although overproduction of reactive oxygen species (ROS) has been suggested to play a major role in its carcinogenicity, the mechanisms of Cr(VI)-induced ROS production remain unclear. In this study, we investigated the role of NADPH oxidase (NOX), one of the major sources of cellular ROS, in Cr(VI)-induced oxidative stress and carcinogenesis. We found that short-term exposure to Cr(VI) (2?M) resulted in a rapid increase in ROS generation in Beas-2B cells, and concomitantly increased NOX activity and expression of NOX members (NOX1-3 and NOX5) and subunits (p22(phox), p47(phox), p40(phox), and p67(phox)). Cr(VI) also induced phosphorylation of p47(phox) and membrane translocation of p47(phox) and p67(phox), further confirming NOX activation. Knockdown of p47(phox) with a short hairpin RNA attenuated the ROS production induced by Cr(VI). Chronic exposure (up to 3 months) to low doses of Cr(VI) (0.125, 0.25, and 0.5?M) also promoted ROS generation and the expression of NOX subunits, such as p47(phox) and p67(phox), but inhibited the expression of main antioxidant enzymes, such as superoxidase dismutase (SOD) and glutathione peroxidase (GPx). Chronic Cr(VI) exposure resulted in transformation of Beas-2B cells, increasing cell proliferation, anchorage independent growth in soft agar, and forming aggressive tumors in nude mice. Stable knockdown of p47(phox) or overexpression of SOD1, SOD2, or catalase (CAT) eliminated Cr(VI)-induced malignant transformation. Our results suggest that NOX plays an important role in Cr(VI)-induced ROS generation and carcinogenesis.","NADPH oxidase activation is required in reactive oxygen species generation and cell transformation induced by hexavalent chromium Abs: Hexavalent chromium [Cr(VI)] is a well-known human carcinogen associated with the incidence of lung cancer. Although overproduction of reactive oxygen species (ROS) has been suggested to play a major role in its carcinogenicity, the mechanisms of Cr(VI)-induced ROS production remain unclear. In this study, we investigated the role of NADPH oxidase (NOX), one of the major sources of cellular ROS, in Cr(VI)-induced oxidative stress and carcinogenesis. We found that short-term exposure to Cr(VI) (2?M) resulted in a rapid increase in ROS generation in Beas-2B cells, and concomitantly increased NOX activity and expression of NOX members (NOX1-3 and NOX5) and subunits (p22(phox), p47(phox), p40(phox), and p67(phox)). Cr(VI) also induced phosphorylation of p47(phox) and membrane translocation of p47(phox) and p67(phox), further confirming NOX activation. Knockdown of p47(phox) with a short hairpin RNA attenuated the ROS production induced by Cr(VI). Chronic exposure (up to 3 months) to low doses of Cr(VI) (0.125, 0.25, and 0.5?M) also promoted ROS generation and the expression of NOX subunits, such as p47(phox) and p67(phox), but inhibited the expression of main antioxidant enzymes, such as superoxidase dismutase (SOD) and glutathione peroxidase (GPx). Chronic Cr(VI) exposure resulted in transformation of Beas-2B cells, increasing cell proliferation, anchorage independent growth in soft agar, and forming aggressive tumors in nude mice. Stable knockdown of p47(phox) or overexpression of SOD1, SOD2, or catalase (CAT) eliminated Cr(VI)-induced malignant transformation. Our results suggest that NOX plays an important role in Cr(VI)-induced ROS generation and carcinogenesis."
844183,Schoonover et al. 2011,"Personal exposure to metal fume, NO2, and O3 among production welders and non-welders",The objective of this study was to characterize personal exposures to welding-related metals and gases for production welders and non-welders in a large manufacturing facility. Welding fume metals and irritant gases nitrogen dioxide (NO(2)) and ozone (O(3)) were sampled for thirty-eight workers. Personal exposure air samples for welding fume metals were collected on 37 mm open face cassettes and nitrogen dioxide and ozone exposure samples were collected with diffusive passive samplers. Samples were analyzed for metals using Inductively Coupled Plasma Mass Spectrometry (ICP-MS) and welding fume metal exposure concentrations were defined as the sum of welding-related metals mass per volume of air sampled. Welding fume metal exposures were highly variable among similar types of welding while NO(2) and O(3) exposure were less variable. Welding fume metal exposures were significantly higher 474 ?g/m(3) for welders than non-welders 60 ?g/m(3) (p=0.001). Welders were exposed to higher concentrations of NO(2) and O(3) than non-welders but the differences were not statistically significant. Welding fume metal exposure concentrations for welders performing gas metal arc welding (GMAW) and shielded metal arc welding (SMAW) were higher than welders performing gas tungsten arc welding (GTAW). Non-welders experienced exposures similar to GTAW welders despite a curtain wall barrier separating welding and non-welding work areas.,"Personal exposure to metal fume, NO2, and O3 among production welders and non-welders Abs: The objective of this study was to characterize personal exposures to welding-related metals and gases for production welders and non-welders in a large manufacturing facility. Welding fume metals and irritant gases nitrogen dioxide (NO(2)) and ozone (O(3)) were sampled for thirty-eight workers. Personal exposure air samples for welding fume metals were collected on 37 mm open face cassettes and nitrogen dioxide and ozone exposure samples were collected with diffusive passive samplers. Samples were analyzed for metals using Inductively Coupled Plasma Mass Spectrometry (ICP-MS) and welding fume metal exposure concentrations were defined as the sum of welding-related metals mass per volume of air sampled. Welding fume metal exposures were highly variable among similar types of welding while NO(2) and O(3) exposure were less variable. Welding fume metal exposures were significantly higher 474 ?g/m(3) for welders than non-welders 60 ?g/m(3) (p=0.001). Welders were exposed to higher concentrations of NO(2) and O(3) than non-welders but the differences were not statistically significant. Welding fume metal exposure concentrations for welders performing gas metal arc welding (GMAW) and shielded metal arc welding (SMAW) were higher than welders performing gas tungsten arc welding (GTAW). Non-welders experienced exposures similar to GTAW welders despite a curtain wall barrier separating welding and non-welding work areas."
841413,Monasterio et al. 2009,Determination of Cr(VI) and Cr(III) species in parenteral solutions using a nanostructured material packed-microcolumn and electrothermal atomic absorption spectrometry,"A sequential on-line preconcentration and separation system for Cr(VI) and Cr(III) species determination was developed in this work. For this purpose, a microcolumn filled with nanostructured alpha-alumina was used for on-line retention of Cr species in a flow-injection system. The method involves the selective elution of Cr(VI) with concentrated ammonia and Cr(III) with 1mol L(-1) nitric acid for sequential injection into an electrothermal atomic absorption spectrometer (ETAAS). Analytical parameters including pH, eluent type, flow rates of sample and eluent, interfering effects, etc., were optimized. The preconcentration factors for Cr(VI) and Cr(III) were 41 and 18, respectively. The limit of detection (LOD) was 1.9 ng L(-1) for Cr(VI) and 6.1 ng L(-1) for Cr(III). The calibration graph was linear with a correlation coefficient of 0.999. The relative standard deviation (RSD) was 8.6% for Cr(VI) and 6.1% for Cr(III) (c = 10 microg L(-1), n=10, sample volume = 25 mL). Verification of the accuracy was carried out by analysis of a standard reference material (NIST SRM 1643e &quot;Trace elements in natural water&quot;) with a reported Cr content of 20.40+/-0.24 microg L(-1). Using the proposed methodology the total Cr content, computed as sum of Cr(III) and Cr(VI), in this SRM was 20.26+/-0.96 microg L(-1). The method was successfully applied to the determination of Cr(VI) and Cr(III) species in parenteral solutions. Concentration of Cr(III) species was found to be in the range of 0.29-3.62 microg L(-1), while Cr(VI) species was not detected in the samples under study.","Determination of Cr(VI) and Cr(III) species in parenteral solutions using a nanostructured material packed-microcolumn and electrothermal atomic absorption spectrometry Abs: A sequential on-line preconcentration and separation system for Cr(VI) and Cr(III) species determination was developed in this work. For this purpose, a microcolumn filled with nanostructured alpha-alumina was used for on-line retention of Cr species in a flow-injection system. The method involves the selective elution of Cr(VI) with concentrated ammonia and Cr(III) with 1mol L(-1) nitric acid for sequential injection into an electrothermal atomic absorption spectrometer (ETAAS). Analytical parameters including pH, eluent type, flow rates of sample and eluent, interfering effects, etc., were optimized. The preconcentration factors for Cr(VI) and Cr(III) were 41 and 18, respectively. The limit of detection (LOD) was 1.9 ng L(-1) for Cr(VI) and 6.1 ng L(-1) for Cr(III). The calibration graph was linear with a correlation coefficient of 0.999. The relative standard deviation (RSD) was 8.6% for Cr(VI) and 6.1% for Cr(III) (c = 10 microg L(-1), n=10, sample volume = 25 mL). Verification of the accuracy was carried out by analysis of a standard reference material (NIST SRM 1643e &quot;Trace elements in natural water&quot;) with a reported Cr content of 20.40+/-0.24 microg L(-1). Using the proposed methodology the total Cr content, computed as sum of Cr(III) and Cr(VI), in this SRM was 20.26+/-0.96 microg L(-1). The method was successfully applied to the determination of Cr(VI) and Cr(III) species in parenteral solutions. Concentration of Cr(III) species was found to be in the range of 0.29-3.62 microg L(-1), while Cr(VI) species was not detected in the samples under study."
834433,Berlinger et al. 2009,Critical evaluation of sequential leaching procedures for the determination of Ni and Mn species in welding fumes,"In this work, welding fume samples were collected in a welding plant, where corrosion-resistant steel and unalloyed structural steel were welded by gas metal arc welding (GMAW) and manual metal arc welding (MMAW) techniques. The welding fumes were sampled with a fixed-point sampling strategy applying Higgins-Dewell cyclones. The following solutions were used to dissolve the different species of Ni and Mn: ammonium citrate solution [1.7% (m/v) diammonium hydrogen citrate and 0.5% (m/v) citric acid monohydrate] for 'soluble' Ni, 50:1 methanol-bromine solution for metallic Ni, 0.01 M ammonium acetate for soluble Mn, 25% acetic acid for Mn(0) and Mn(2+) and 0.5% hydroxylammonium chloride in 25% acetic acid for Mn(3+) and Mn(4+). 'Insoluble' Ni and Mn contents of the samples were determined after microwave-assisted digestion with the mixture of concentrated (cc). HNO(3), cc. HCl and cc. HF. The sample solutions were analysed by inductively coupled plasma quadrupole mass spectrometry and inductively coupled plasma atomic emission spectrometry. The levels of total Ni and Mn measured in the workplace air were different because of significant differences of the fume generation rates and the distributions of the components in the welding fumes between the welding processes. For quality control of the leaching process, dissolution of the pure stoichiometric Mn and Ni compounds and their mixtures weighing was investigated using the optimized leaching conditions. The results showed the adequacy of the procedure for the pure metal compounds. Based on the extraction procedures, the predominant oxidation states of Ni and Mn proved to be very different depending on the welding techniques and type of the welded steels. The largest amount of Mn in GMAW fumes were found as insoluble Mn (46 and 35% in case of corrosion-resistant steel and unalloyed structural steel, respectively), while MMAW fumes contain mainly soluble Mn, Mn(0) and Mn(2+) (78%) and Mn(3+) and Mn(4+) (54%) in case of corrosion-resistant steel and unalloyed structural steel, respectively. According to the results of the leaching procedures, GMAW fumes are rich in oxidic Ni (79%), while Ni compounds in welding fumes generated during MMAW are mainly in easily soluble form (44%). The crystalline phases were identified in each welding fume by X-ray powder diffraction (XRPD) technique as well. From the XRPD spectra, it is clear that GMAW fumes contain predominantly magnetite (FeFe(2)O(4)). In case of structural steel welding, there was a little amount of ferrite (alpha-Fe) also found. Welding fume generated during MMAW of structural steel contained a complex alkali-alkali earth fluoride phase (KCaF(3)-CaF(2)) and some magnetite and jakobsite (MnFe(2)O(4)). The XRPD results did not fully confirm the ones obtained from the extraction experiments. However, some results, for example the rate of soluble Ni and Mn compounds compared to the total, can be useful for further investigations of welding fumes.","Critical evaluation of sequential leaching procedures for the determination of Ni and Mn species in welding fumes Abs: In this work, welding fume samples were collected in a welding plant, where corrosion-resistant steel and unalloyed structural steel were welded by gas metal arc welding (GMAW) and manual metal arc welding (MMAW) techniques. The welding fumes were sampled with a fixed-point sampling strategy applying Higgins-Dewell cyclones. The following solutions were used to dissolve the different species of Ni and Mn: ammonium citrate solution [1.7% (m/v) diammonium hydrogen citrate and 0.5% (m/v) citric acid monohydrate] for 'soluble' Ni, 50:1 methanol-bromine solution for metallic Ni, 0.01 M ammonium acetate for soluble Mn, 25% acetic acid for Mn(0) and Mn(2+) and 0.5% hydroxylammonium chloride in 25% acetic acid for Mn(3+) and Mn(4+). 'Insoluble' Ni and Mn contents of the samples were determined after microwave-assisted digestion with the mixture of concentrated (cc). HNO(3), cc. HCl and cc. HF. The sample solutions were analysed by inductively coupled plasma quadrupole mass spectrometry and inductively coupled plasma atomic emission spectrometry. The levels of total Ni and Mn measured in the workplace air were different because of significant differences of the fume generation rates and the distributions of the components in the welding fumes between the welding processes. For quality control of the leaching process, dissolution of the pure stoichiometric Mn and Ni compounds and their mixtures weighing was investigated using the optimized leaching conditions. The results showed the adequacy of the procedure for the pure metal compounds. Based on the extraction procedures, the predominant oxidation states of Ni and Mn proved to be very different depending on the welding techniques and type of the welded steels. The largest amount of Mn in GMAW fumes were found as insoluble Mn (46 and 35% in case of corrosion-resistant steel and unalloyed structural steel, respectively), while MMAW fumes contain mainly soluble Mn, Mn(0) and Mn(2+) (78%) and Mn(3+) and Mn(4+) (54%) in case of corrosion-resistant steel and unalloyed structural steel, respectively. According to the results of the leaching procedures, GMAW fumes are rich in oxidic Ni (79%), while Ni compounds in welding fumes generated during MMAW are mainly in easily soluble form (44%). The crystalline phases were identified in each welding fume by X-ray powder diffraction (XRPD) technique as well. From the XRPD spectra, it is clear that GMAW fumes contain predominantly magnetite (FeFe(2)O(4)). In case of structural steel welding, there was a little amount of ferrite (alpha-Fe) also found. Welding fume generated during MMAW of structural steel contained a complex alkali-alkali earth fluoride phase (KCaF(3)-CaF(2)) and some magnetite and jakobsite (MnFe(2)O(4)). The XRPD results did not fully confirm the ones obtained from the extraction experiments. However, some results, for example the rate of soluble Ni and Mn compounds compared to the total, can be useful for further investigations of welding fumes."
834212,Chen et al. ,Renoprotective potential of Macrothelypteris torresiana via ameliorating oxidative stress and proinflammatory cytokines,"ETHNOPHARMACOLOGICAL RELEVANCE: Macrothelypteris torresiana is traditionally used in Chinese folk medicine for the treatment of edema for patients suffering from kidney/bladder problems due to its satisfactory therapeutic effectiveness. AIM OF THE STUDY: The aim of this study was to investigate the renoprotective nature of the total polyphenols fraction from Macrothelypteris torresiana (PMT). MATERIALS AND METHODS: The biochemical criterions of plasma and kidney tissues were evaluated to study the effects of PMT on puromycin aminonucleoside-induced chronic nephrotic syndrome (NS) in hyperlipidemic mice. RESULTS: In this study, the NS and hyperlipidemia were ameliorated after 9 weeks administration of PMT. Besides, PMT was able to modulate the level of renal oxidative stress and vascular endothelial growth factor-nitric oxide (VEGF-NO) pathway. CONCLUSIONS: It represented a potential resource of PMT for the treatment of NS involved in metabolic syndrome.","Renoprotective potential of Macrothelypteris torresiana via ameliorating oxidative stress and proinflammatory cytokines Abs: ETHNOPHARMACOLOGICAL RELEVANCE: Macrothelypteris torresiana is traditionally used in Chinese folk medicine for the treatment of edema for patients suffering from kidney/bladder problems due to its satisfactory therapeutic effectiveness. AIM OF THE STUDY: The aim of this study was to investigate the renoprotective nature of the total polyphenols fraction from Macrothelypteris torresiana (PMT). MATERIALS AND METHODS: The biochemical criterions of plasma and kidney tissues were evaluated to study the effects of PMT on puromycin aminonucleoside-induced chronic nephrotic syndrome (NS) in hyperlipidemic mice. RESULTS: In this study, the NS and hyperlipidemia were ameliorated after 9 weeks administration of PMT. Besides, PMT was able to modulate the level of renal oxidative stress and vascular endothelial growth factor-nitric oxide (VEGF-NO) pathway. CONCLUSIONS: It represented a potential resource of PMT for the treatment of NS involved in metabolic syndrome."
833190,Bayramo?lu et al. 2011,Reversible immobilization of uricase on conductive polyaniline brushes grafted on polyacrylonitrile film,"Polyacrylonitrile film (PAN) surfaces were modified with chemical polymerization of conductive polyaniline (PANI) in the presence of potassium dichromate as an oxidizing agent. The conductive films were used for immobilization of uricase. The surface resistance of the conductive film in this work was found to be 0.97 k?/cm. The maximum amount of immobilized enzyme on conductive film containing 2.4% PANI was about 216 ?g/cm(2). The optimum pH for free and immobilized enzymes was observed at 7.0 and 7.5, respectively. The K (m) values for free and immobilized uricase were found to be 94 and 138 ?M, respectively. V (max) values were calculated as 1.87 and 1.63 U/mg protein for the free and immobilized enzymes, respectively. Immobilized uricase exhibited ~68% of its original activity even after 2 months of storage at 4 °C while the free enzyme lost its initial activity within 4 weeks.","Reversible immobilization of uricase on conductive polyaniline brushes grafted on polyacrylonitrile film Abs: Polyacrylonitrile film (PAN) surfaces were modified with chemical polymerization of conductive polyaniline (PANI) in the presence of potassium dichromate as an oxidizing agent. The conductive films were used for immobilization of uricase. The surface resistance of the conductive film in this work was found to be 0.97 k?/cm. The maximum amount of immobilized enzyme on conductive film containing 2.4% PANI was about 216 ?g/cm(2). The optimum pH for free and immobilized enzymes was observed at 7.0 and 7.5, respectively. The K (m) values for free and immobilized uricase were found to be 94 and 138 ?M, respectively. V (max) values were calculated as 1.87 and 1.63 U/mg protein for the free and immobilized enzymes, respectively. Immobilized uricase exhibited ~68% of its original activity even after 2 months of storage at 4 °C while the free enzyme lost its initial activity within 4 weeks."
832156,Azad et al. 2010,Nitric oxide-mediated bcl-2 stabilization potentiates malignant transformation of human lung epithelial cells,"Hexavalent chromium (Cr(VI)) compounds are known human carcinogens associated with the incidence of lung cancer. Although a direct correlation between Cr(VI) exposure and lung cancer has been established, several studies aimed at generating animal models for Cr(VI) have yielded inconsistent data that do not affirmatively support findings from epidemiologic studies. Because the lack of a good animal model has hindered the identification of molecular mechanisms involved in Cr(VI) exposure, we developed an in vitro model that facilitates mechanistic studies of Cr(VI)-induced carcinogenesis. We report here that long-term exposure to Cr(VI) leads to the malignant transformation of nontumorigenic human lung epithelial cells. Cr(VI)-transformed cells exhibited loss of contact inhibition, colony formation, and increased rates of cell invasion, migration, and proliferation, as compared with passage-matched control cells. Cr(VI)-transformed cells evaded apoptosis by a mechanism involving S-nitrosylation and stabilization of Bcl-2 protein in a nitric oxide-dependent manner. This study establishes an important in vitro model that facilitates mechanistic studies of Cr(VI)-induced carcinogenesis, and elucidates a novel mechanism that causes apoptosis-resistant malignant transformation of nontumorigenic lung cells in response to a human carcinogen.","Nitric oxide-mediated bcl-2 stabilization potentiates malignant transformation of human lung epithelial cells Abs: Hexavalent chromium (Cr(VI)) compounds are known human carcinogens associated with the incidence of lung cancer. Although a direct correlation between Cr(VI) exposure and lung cancer has been established, several studies aimed at generating animal models for Cr(VI) have yielded inconsistent data that do not affirmatively support findings from epidemiologic studies. Because the lack of a good animal model has hindered the identification of molecular mechanisms involved in Cr(VI) exposure, we developed an in vitro model that facilitates mechanistic studies of Cr(VI)-induced carcinogenesis. We report here that long-term exposure to Cr(VI) leads to the malignant transformation of nontumorigenic human lung epithelial cells. Cr(VI)-transformed cells exhibited loss of contact inhibition, colony formation, and increased rates of cell invasion, migration, and proliferation, as compared with passage-matched control cells. Cr(VI)-transformed cells evaded apoptosis by a mechanism involving S-nitrosylation and stabilization of Bcl-2 protein in a nitric oxide-dependent manner. This study establishes an important in vitro model that facilitates mechanistic studies of Cr(VI)-induced carcinogenesis, and elucidates a novel mechanism that causes apoptosis-resistant malignant transformation of nontumorigenic lung cells in response to a human carcinogen."
830802,Altenburger et al. 2010,Proposing a pH stabilised nutrient medium for algal growth bioassays,"Ecotoxicological assessment of chemicals and contaminated sites relies on bioassays using apical endpoints such as detection of growth inhibition using suspension cultures of green algae. For valid effect assessment observable responses should be causally linked to chemical exposure and thus confounding factors should be minimised. In this study we report that concentration response relationships for substances in current standardised protocols for unicellular algal growth assays are prone to variation from ill-defined assay conditions. The currently used growth media are not optimised to provide a stable pH regime for an exposure period of 72h, resulting in undefined speciation for charged or ionising molecules. We therefore propose a modified pH-stabilised growth medium for algal bioassays and demonstrate that this can substantially reduce variation in effect determination for reference compounds.","Proposing a pH stabilised nutrient medium for algal growth bioassays Abs: Ecotoxicological assessment of chemicals and contaminated sites relies on bioassays using apical endpoints such as detection of growth inhibition using suspension cultures of green algae. For valid effect assessment observable responses should be causally linked to chemical exposure and thus confounding factors should be minimised. In this study we report that concentration response relationships for substances in current standardised protocols for unicellular algal growth assays are prone to variation from ill-defined assay conditions. The currently used growth media are not optimised to provide a stable pH regime for an exposure period of 72h, resulting in undefined speciation for charged or ionising molecules. We therefore propose a modified pH-stabilised growth medium for algal bioassays and demonstrate that this can substantially reduce variation in effect determination for reference compounds."
819555,O'Flaherty 1998,Physiologically based models of metal kinetics,"The issues confronting the modeler of metals kinetics are somewhat different from those with which the modeler of organic chemical behavior is faced. Particularly important features of metals kinetics include metal-protein binding and metal-metal interactions. Reduction, and for some metals oxidation, is frequently an intrinsic part of metal metabolism. Alkylation/dealkylation reactions may or may not render the metal less active, and the behavior of alkylated or dealkylated metabolites must often be included in a complete kinetic model. Despite these complexities, the kinetics of metals are as amenable to the techniques of physiologically based modeling as are the kinetics of organic chemicals. Like all models, those for metals kinetics have the potential to organize a variety of observations, sometimes including apparently inconsistent observations, into a coherent framework of behavior, to identify needs for more complete experimental information, and to assist the risk assessor in making judgments concerning dose-response relationships. Development of physiologically based models of the kinetic behavior of metals is in its very early stages. The kinetics of only four metals, arsenic, chromium, mercury, and lead, have been modeled with any degree of completeness. Of these, the lead model is the most fully realized at the present time. The chromium and mercury models are still in the process of development, and experimental data are being gathered to support further development and refinement of the arsenic model. We may expect to see continued progress made on these models and their practical applications, as well as the development of new models for other toxicologically significant metals such as cadmium, manganese, nickel, and aluminum.","Physiologically based models of metal kinetics Abs: The issues confronting the modeler of metals kinetics are somewhat different from those with which the modeler of organic chemical behavior is faced. Particularly important features of metals kinetics include metal-protein binding and metal-metal interactions. Reduction, and for some metals oxidation, is frequently an intrinsic part of metal metabolism. Alkylation/dealkylation reactions may or may not render the metal less active, and the behavior of alkylated or dealkylated metabolites must often be included in a complete kinetic model. Despite these complexities, the kinetics of metals are as amenable to the techniques of physiologically based modeling as are the kinetics of organic chemicals. Like all models, those for metals kinetics have the potential to organize a variety of observations, sometimes including apparently inconsistent observations, into a coherent framework of behavior, to identify needs for more complete experimental information, and to assist the risk assessor in making judgments concerning dose-response relationships. Development of physiologically based models of the kinetic behavior of metals is in its very early stages. The kinetics of only four metals, arsenic, chromium, mercury, and lead, have been modeled with any degree of completeness. Of these, the lead model is the most fully realized at the present time. The chromium and mercury models are still in the process of development, and experimental data are being gathered to support further development and refinement of the arsenic model. We may expect to see continued progress made on these models and their practical applications, as well as the development of new models for other toxicologically significant metals such as cadmium, manganese, nickel, and aluminum."
819363,O'Flaherty et al. 2001,A physiologically based model for the ingestion of chromium(III) and chromium(VI) by humans,"A physiologically based model of human chromium kinetics has been developed, based on an existing physiologically based model of human body and bone growth (O'Flaherty, 1993, Toxicol. Appl. Pharmacol. 118, 16-29; 1995a, Toxicol. Appl. Pharmacol. 131, 297-308; 2000, Toxicol. Sci. 55, 171-18) and an existing physiologically based model of chromium kinetics in rats (O'Flaherty, 1996, Toxicol. Appl. Pharmacol. 138, 54-64). Key features of the adapted model, specific to chromium, include differential absorption of Cr(VI) and Cr(III), rapid reduction of Cr(VI) to Cr(III) in all body fluids and tissues, modest incorporation of chromium into bone, and concentration-dependent urinary clearance consistent with parallel renal processes that conserve chromium efficiently at ambient exposure levels. The model does not include a physiologic lung compartment, but it can be used to estimate an upper limit on pulmonary absorption of inhaled chromium. The model was calibrated against blood and urine chromium concentration data from a group of controlled studies in which adult human volunteers drank solutions generally containing up to 10 mg/day of soluble inorganic salts of either Cr(III) (chromic chloride, CrCl(3)) or Cr(VI) (potassium dichromate, K(2)Cr(2)O(7)) (Finley et al., 1997, Toxicol. Appl. Pharmacol. 142, 151-159; Kerger et al., 1996, Toxicol. Appl. Pharmacol. 141, 145-158; Paustenbach et al., 1996, J. Toxicol. Environ. Health 49, 453-461). In one of the studies, in which the chromium was ingested in orange juice, urinary clearance was observed to be more rapid than when inorganic chromium was ingested. Chromium kinetics were shown not to be dependent on the oxidation state of the administered chromium except in respect to the amount absorbed at these ambient and moderate-to-high exposures. The fraction absorbed from administered Cr(VI) compounds was highly variable and was presumably strongly dependent on the degree of reduction in the gastrointestinal tract, that is, on the amount and nature of the stomach contents at the time of Cr(VI) ingestion. The physiologically based model is applicable to both single-dose oral studies and chronic oral exposure, in that it adequately reproduced the time dependence of blood plasma concentrations and rates of urinary chromium excretion in one of the subjects who, in a separate experiment, ingested daily 4 mg of an inorganic Cr(VI) salt in 5 subdivided doses of 0.8 mg each for a total of 17 days. The high degree of variability of fractional absorption of Cr(VI) from the gastrointestinal tract leads to uncertainty in the assignment of a meaningful value to this parameter as applied to single Cr(VI) doses. To model chronic oral chromium exposure at ambient or moderately above-ambient levels, the physiologically based model in its present form should be usable with urinary clearance set to a constant value of 1-2 liters/day and the gastrointestinal absorption rate constants set at 0.25/day for Cr(III) and 2.5/day for Cr(VI). The model code is given in full in the Appendix.","A physiologically based model for the ingestion of chromium(III) and chromium(VI) by humans Abs: A physiologically based model of human chromium kinetics has been developed, based on an existing physiologically based model of human body and bone growth (O'Flaherty, 1993, Toxicol. Appl. Pharmacol. 118, 16-29; 1995a, Toxicol. Appl. Pharmacol. 131, 297-308; 2000, Toxicol. Sci. 55, 171-18) and an existing physiologically based model of chromium kinetics in rats (O'Flaherty, 1996, Toxicol. Appl. Pharmacol. 138, 54-64). Key features of the adapted model, specific to chromium, include differential absorption of Cr(VI) and Cr(III), rapid reduction of Cr(VI) to Cr(III) in all body fluids and tissues, modest incorporation of chromium into bone, and concentration-dependent urinary clearance consistent with parallel renal processes that conserve chromium efficiently at ambient exposure levels. The model does not include a physiologic lung compartment, but it can be used to estimate an upper limit on pulmonary absorption of inhaled chromium. The model was calibrated against blood and urine chromium concentration data from a group of controlled studies in which adult human volunteers drank solutions generally containing up to 10 mg/day of soluble inorganic salts of either Cr(III) (chromic chloride, CrCl(3)) or Cr(VI) (potassium dichromate, K(2)Cr(2)O(7)) (Finley et al., 1997, Toxicol. Appl. Pharmacol. 142, 151-159; Kerger et al., 1996, Toxicol. Appl. Pharmacol. 141, 145-158; Paustenbach et al., 1996, J. Toxicol. Environ. Health 49, 453-461). In one of the studies, in which the chromium was ingested in orange juice, urinary clearance was observed to be more rapid than when inorganic chromium was ingested. Chromium kinetics were shown not to be dependent on the oxidation state of the administered chromium except in respect to the amount absorbed at these ambient and moderate-to-high exposures. The fraction absorbed from administered Cr(VI) compounds was highly variable and was presumably strongly dependent on the degree of reduction in the gastrointestinal tract, that is, on the amount and nature of the stomach contents at the time of Cr(VI) ingestion. The physiologically based model is applicable to both single-dose oral studies and chronic oral exposure, in that it adequately reproduced the time dependence of blood plasma concentrations and rates of urinary chromium excretion in one of the subjects who, in a separate experiment, ingested daily 4 mg of an inorganic Cr(VI) salt in 5 subdivided doses of 0.8 mg each for a total of 17 days. The high degree of variability of fractional absorption of Cr(VI) from the gastrointestinal tract leads to uncertainty in the assignment of a meaningful value to this parameter as applied to single Cr(VI) doses. To model chronic oral chromium exposure at ambient or moderately above-ambient levels, the physiologically based model in its present form should be usable with urinary clearance set to a constant value of 1-2 liters/day and the gastrointestinal absorption rate constants set at 0.25/day for Cr(III) and 2.5/day for Cr(VI). The model code is given in full in the Appendix."
819109,Paustenbach et al. 2003,Human health risk and exposure assessment of chromium (VI) in tap water,"Hexavalent chromium [Cr(VI)] has been detected in groundwater across the United States due to industrial and military operations, including plating, painting, cooling-tower water, and chromate production. Because inhalation of Cr(VI) can cause lung cancer in some persons exposed to a sufficient airborne concentration, questions have been raised about the possible hazards associated with exposure to Cr(VI) in tap water via ingestion, inhalation, and dermal contact. Although ingested Cr(VI) is generally known to be converted to Cr(III) in the stomach following ingestion, prior to the mid-1980s a quantitative analysis of the reduction capacity of the human stomach had not been conducted. Thus, risk assessments of the human health hazard posed by contaminated drinking water contained some degree of uncertainty. This article presents the results of nine studies, including seven dose reconstruction or simulation studies involving human volunteers, that quantitatively characterize the absorbed dose of Cr(VI) following contact with tap water via all routes of exposure. The methodology used here illustrates an approach that permits one to understand, within a very narrow range, the possible intake of Cr(VI) and the associated health risks for situations where little is known about historical concentrations of Cr(VI). Using red blood cell uptake and sequestration of chromium as an in vivo metric of Cr(VI) absorption, the primary conclusions of these studies were that: (1) oral exposure to concentrations of Cr(VI) in water up to 10 mg/L (ppm) does not overwhelm the reductive capacity of the stomach and blood, (2) the inhaled dose of Cr(VI) associated with showering at concentrations up to 10 mg/L is so small as to pose a de minimis cancer hazard, and (3) dermal exposures to Cr(VI) in water at concentrations as high as 22 mg/L do not overwhelm the reductive capacity of the skin or blood. Because Cr(VI) in water appears yellow at approximately 1-2 mg/L, the studies represent conditions beyond the worst-case scenario for voluntary human exposure. Based on a physiologically based pharmacokinetic model for chromium derived from published studies, coupled with the dose reconstruction studies presented in this article, the available information clearly indicates that (1) Cr(VI) ingested in tap water at concentrations below 2 mg/L is rapidly reduced to Cr(III), and (2) even trace amounts of Cr(VI) are not systemically circulated. This assessment indicates that exposure to Cr(VI) in tap water via all plausible routes of exposure, at concentrations well in excess of the current U.S. Environmental Protection Agency (EPA) maximum contaminant level of 100 microg/L (ppb), and perhaps those as high as several parts per million, should not pose an acute or chronic health hazard to humans. These conclusions are consistent with those recently reached by a panel of experts convened by the State of California.","Human health risk and exposure assessment of chromium (VI) in tap water Abs: Hexavalent chromium [Cr(VI)] has been detected in groundwater across the United States due to industrial and military operations, including plating, painting, cooling-tower water, and chromate production. Because inhalation of Cr(VI) can cause lung cancer in some persons exposed to a sufficient airborne concentration, questions have been raised about the possible hazards associated with exposure to Cr(VI) in tap water via ingestion, inhalation, and dermal contact. Although ingested Cr(VI) is generally known to be converted to Cr(III) in the stomach following ingestion, prior to the mid-1980s a quantitative analysis of the reduction capacity of the human stomach had not been conducted. Thus, risk assessments of the human health hazard posed by contaminated drinking water contained some degree of uncertainty. This article presents the results of nine studies, including seven dose reconstruction or simulation studies involving human volunteers, that quantitatively characterize the absorbed dose of Cr(VI) following contact with tap water via all routes of exposure. The methodology used here illustrates an approach that permits one to understand, within a very narrow range, the possible intake of Cr(VI) and the associated health risks for situations where little is known about historical concentrations of Cr(VI). Using red blood cell uptake and sequestration of chromium as an in vivo metric of Cr(VI) absorption, the primary conclusions of these studies were that: (1) oral exposure to concentrations of Cr(VI) in water up to 10 mg/L (ppm) does not overwhelm the reductive capacity of the stomach and blood, (2) the inhaled dose of Cr(VI) associated with showering at concentrations up to 10 mg/L is so small as to pose a de minimis cancer hazard, and (3) dermal exposures to Cr(VI) in water at concentrations as high as 22 mg/L do not overwhelm the reductive capacity of the skin or blood. Because Cr(VI) in water appears yellow at approximately 1-2 mg/L, the studies represent conditions beyond the worst-case scenario for voluntary human exposure. Based on a physiologically based pharmacokinetic model for chromium derived from published studies, coupled with the dose reconstruction studies presented in this article, the available information clearly indicates that (1) Cr(VI) ingested in tap water at concentrations below 2 mg/L is rapidly reduced to Cr(III), and (2) even trace amounts of Cr(VI) are not systemically circulated. This assessment indicates that exposure to Cr(VI) in tap water via all plausible routes of exposure, at concentrations well in excess of the current U.S. Environmental Protection Agency (EPA) maximum contaminant level of 100 microg/L (ppb), and perhaps those as high as several parts per million, should not pose an acute or chronic health hazard to humans. These conclusions are consistent with those recently reached by a panel of experts convened by the State of California."
818659,Hays et al. 2003,Refining the PBPK model for chromium(VI) in humans,"A physiologically based pharmacokinetic (PBPK) model for trivalent and hexavalent chromium [Cr(VI)] in humans was recently published (O'Flaherty et al., 2000). A critical parameter within the model is the rate at which Cr(VI) is reduced to Cr(III) in the gastrointestinal tract (GI). Two limitations of the current model are: 1) that it relies on limited data regarding the gastric reduction capacity of humans, and 2) the GI tract is described as a single combined stomach and small intestine (SI) compartment. This latter limitation requires that absorption and reduction processes be described as simultaneous competing reactions, whereas physiologically, reduction of Cr(VI) occurs primarily in the stomach followed by absorption in the SI. This work describes refinements to the current PBPK model. Specifically, we used new in vitro reduction rate data, simulating a variety of conditions (e.g., fasted, fed, antacids, diluted stomach fluid), to better quantify the rate of Cr(VI) reduction in the stomach, focusing on the rate within the first few minutes before transfer of stomach contents to the SI occurs while fasting. Based on these new data, first-order reduction rate constants and gastric half-lives were calculated to range from 10 to 0.7 minutes, with an average of 2.7 minutes. These rates are up to 14 times faster than that used in the current PBPK model. We also modified the current model, separating the stomach compartment (where reduction occurs) from the SI compartment (where reduction continues, but at a slower rate, and absorption occurs). The revised model provides vastly different estimates of the amount of Cr(VI) that might be absorbed systemically by humans following ingestion of Cr(VI), as compared to the first model. These results are valuable for understanding the potential risks associated with Cr(VI) in drinking water and the potential threshold for absorbing Cr(VI) following ingestion.","Refining the PBPK model for chromium(VI) in humans Abs: A physiologically based pharmacokinetic (PBPK) model for trivalent and hexavalent chromium [Cr(VI)] in humans was recently published (O'Flaherty et al., 2000). A critical parameter within the model is the rate at which Cr(VI) is reduced to Cr(III) in the gastrointestinal tract (GI). Two limitations of the current model are: 1) that it relies on limited data regarding the gastric reduction capacity of humans, and 2) the GI tract is described as a single combined stomach and small intestine (SI) compartment. This latter limitation requires that absorption and reduction processes be described as simultaneous competing reactions, whereas physiologically, reduction of Cr(VI) occurs primarily in the stomach followed by absorption in the SI. This work describes refinements to the current PBPK model. Specifically, we used new in vitro reduction rate data, simulating a variety of conditions (e.g., fasted, fed, antacids, diluted stomach fluid), to better quantify the rate of Cr(VI) reduction in the stomach, focusing on the rate within the first few minutes before transfer of stomach contents to the SI occurs while fasting. Based on these new data, first-order reduction rate constants and gastric half-lives were calculated to range from 10 to 0.7 minutes, with an average of 2.7 minutes. These rates are up to 14 times faster than that used in the current PBPK model. We also modified the current model, separating the stomach compartment (where reduction occurs) from the SI compartment (where reduction continues, but at a slower rate, and absorption occurs). The revised model provides vastly different estimates of the amount of Cr(VI) that might be absorbed systemically by humans following ingestion of Cr(VI), as compared to the first model. These results are valuable for understanding the potential risks associated with Cr(VI) in drinking water and the potential threshold for absorbing Cr(VI) following ingestion."
813242,Anon 1981,Hazardous materials section,"This section provides nomenclature, physical and chemical data, computerised structural formulas and new toxicity and hazard information about acetylacetone, acrylic acid, adipic acid, allyl alcohol, allyl chloride, 4-amino-2-nitrophenol, barium and its isotopes, carbachol, carbon-14, carbon monoxide, cholesterol, chromic oxide, 1-decene, 2,4-dichlorophenol, bis(2-ethylhexyl) phthalate, dimethyl cyanamide, ethyl alcohol, 2-ethylhexyl acrylate, fuel oils, heroin, hydrogen chloride, lead chromate, nitros oxide, 2-octanol, papain, paraffin and paraffin wax fume, potassium bromate, potassium chromate, potassium cyanate, quassin, strontium chromate, tallow, vinyl ether, m-xylene, 3,5-xylenol, zinc and its isotopes, zinc acetate, zinc chloride, zinc chromate, zinc fluroborate.","Hazardous materials section Abs: This section provides nomenclature, physical and chemical data, computerised structural formulas and new toxicity and hazard information about acetylacetone, acrylic acid, adipic acid, allyl alcohol, allyl chloride, 4-amino-2-nitrophenol, barium and its isotopes, carbachol, carbon-14, carbon monoxide, cholesterol, chromic oxide, 1-decene, 2,4-dichlorophenol, bis(2-ethylhexyl) phthalate, dimethyl cyanamide, ethyl alcohol, 2-ethylhexyl acrylate, fuel oils, heroin, hydrogen chloride, lead chromate, nitros oxide, 2-octanol, papain, paraffin and paraffin wax fume, potassium bromate, potassium chromate, potassium cyanate, quassin, strontium chromate, tallow, vinyl ether, m-xylene, 3,5-xylenol, zinc and its isotopes, zinc acetate, zinc chloride, zinc chromate, zinc fluroborate."
791157,Li et al. 1988,A review and analysis of the chinese hamster ovary hypoxanthine-guanine phosphoribosyltransferase assay to determine the mutagenicity of chemical agents a report of phase iii of the usa epa gene-tox program,BIOSIS COPYRIGHT: BIOL ABS. RRM REVIEW TOXICITY TESTING CARCINOGENICITY TESTING,A review and analysis of the chinese hamster ovary hypoxanthine-guanine phosphoribosyltransferase assay to determine the mutagenicity of chemical agents a report of phase iii of the usa epa gene-tox program Abs: BIOSIS COPYRIGHT: BIOL ABS. RRM REVIEW TOXICITY TESTING CARCINOGENICITY TESTING
790852,Rossman et al. 1991,Performance of 133 compounds in the lambda prophage induction endpoint of the microscreen assay and a comparison with s.typhimurium mutagenicity and rodent carcinogenicity assays,"The Microscreen assay was developed as a means of testing very small samples, as in complex mixture fractionation. It is a multi-endpoint assay which utilizes E. coli WP2s(?). Exposure takes place to serial dilutions of the test compound in microtitre wells (250 ?l) followed by sampling from wells in which growth has occurred (‘non-toxic wells’). Although a number of different endpoints can be measured, only the prophage induction endpoint (the first one developed) has been extensively tested. Results with 133 compounds are presented. These include 111 compounds which have been tested in the S. typhimurium assay and 66 compounds for which both rodent bioassay and S. typhimurium assay data exists. The concordance for the Microscreen assay and the S. typhimurium assay was 71%. For this group of compounds, the sensitivity of the Microscreen assay in detecting carcinogens was 76% compared with 58% for the S. typhimurium assay. However, the S. typhimurium assay was somewhat more specific (69%) compared with the Microscreen (56%). The overall association between carcinogenicity and Microscreen results was statistically significant (p = 0.029), whereas for the S. typhimurium assay the association with carcinogenicity was non-significant (p = 0.086). The Microscreen assay was able to detect halogenated compounds better than the S. typhimurium assay. The Microscreen assay should prove useful in complex mixture fractionation, or in other situations where sample size is limiting.","Performance of 133 compounds in the lambda prophage induction endpoint of the microscreen assay and a comparison with s.typhimurium mutagenicity and rodent carcinogenicity assays Abs: The Microscreen assay was developed as a means of testing very small samples, as in complex mixture fractionation. It is a multi-endpoint assay which utilizes E. coli WP2s(?). Exposure takes place to serial dilutions of the test compound in microtitre wells (250 ?l) followed by sampling from wells in which growth has occurred (‘non-toxic wells’). Although a number of different endpoints can be measured, only the prophage induction endpoint (the first one developed) has been extensively tested. Results with 133 compounds are presented. These include 111 compounds which have been tested in the S. typhimurium assay and 66 compounds for which both rodent bioassay and S. typhimurium assay data exists. The concordance for the Microscreen assay and the S. typhimurium assay was 71%. For this group of compounds, the sensitivity of the Microscreen assay in detecting carcinogens was 76% compared with 58% for the S. typhimurium assay. However, the S. typhimurium assay was somewhat more specific (69%) compared with the Microscreen (56%). The overall association between carcinogenicity and Microscreen results was statistically significant (p = 0.029), whereas for the S. typhimurium assay the association with carcinogenicity was non-significant (p = 0.086). The Microscreen assay was able to detect halogenated compounds better than the S. typhimurium assay. The Microscreen assay should prove useful in complex mixture fractionation, or in other situations where sample size is limiting."
789675,Stevenson et al. 2002,Measurement of the intracellular distribution of reduced glutathione in cultured rat hepatocytes using monochlorobimane and confocal laser scanning microscopy,"Intracellular reduced glutathione (GSH) plays a key role in protecting cells from toxicity by maintaining intracellular redox status, conjugating with electrophilic xenobiotics and free radicals, and detoxifying reactive peroxides. Several toxic chemicals interact with GSH during their metabolism, and in many cases it would be advantageous to monitor intracellular GSH distribution during that process. We present a novel method to monitor intracellular GSH levels utilising a new laser light source, InGaN laser, for confocal microscopy and fluorescent detection of monochlorobimane (mBCl) binding to GSH. The sensitivity of the method was compared with that obtained using o-phthalaldehyde (OPT) as a fluorochrome. In the presence of a source of glutathione S-transferase (GST), mBCl was specific for GSH, forming a fluorescent conjugate that was retained in hepatocytes for at least 35 min. mBCl was able to detect the GSH depleting effects caused by progressive inhibition of GSH synthesis by increasing concentrations of buthionine sulfoximine. It effectively monitored the rapid effects of menadione and chromium VI metabolism on intracellular GSH levels in the cytosol and nuclear compartments of the cells. The combination of a specific stain, a novel laser light source and confocal microscopy provide a valuable system for mechanistic studies of intracellular GSH distribution in toxicology studies.","Measurement of the intracellular distribution of reduced glutathione in cultured rat hepatocytes using monochlorobimane and confocal laser scanning microscopy Abs: Intracellular reduced glutathione (GSH) plays a key role in protecting cells from toxicity by maintaining intracellular redox status, conjugating with electrophilic xenobiotics and free radicals, and detoxifying reactive peroxides. Several toxic chemicals interact with GSH during their metabolism, and in many cases it would be advantageous to monitor intracellular GSH distribution during that process. We present a novel method to monitor intracellular GSH levels utilising a new laser light source, InGaN laser, for confocal microscopy and fluorescent detection of monochlorobimane (mBCl) binding to GSH. The sensitivity of the method was compared with that obtained using o-phthalaldehyde (OPT) as a fluorochrome. In the presence of a source of glutathione S-transferase (GST), mBCl was specific for GSH, forming a fluorescent conjugate that was retained in hepatocytes for at least 35 min. mBCl was able to detect the GSH depleting effects caused by progressive inhibition of GSH synthesis by increasing concentrations of buthionine sulfoximine. It effectively monitored the rapid effects of menadione and chromium VI metabolism on intracellular GSH levels in the cytosol and nuclear compartments of the cells. The combination of a specific stain, a novel laser light source and confocal microscopy provide a valuable system for mechanistic studies of intracellular GSH distribution in toxicology studies."
789554,Klapiszewska et al. 2003,Highly dispersed green silicate and oxide pigments precipitated from model systems of postgalvanic waste,"A procedure was worked out to obtain highly dispersed green silicate and oxide pigments precipitated from postgalvanic waste. The highly dispersed chromium(III) silicates and oxides were produced from the waste, originating from chromium plating, by reduction of Cr(VI) to Cr(III) employing various reducing agents. All the reductions were conducted in an acidic medium. Solutions of Cr(III), obtained in reducing processes, were employed to precipitate silicate pigments (using sodium metasilicate solution and containing mainly chromium(III) silicates) and oxide pigments (using sodium hydroxide and containing chromium(III) oxides). The precipitated silicates and oxides were subjected to a comprehensive physicochemical analysis (estimating bulk density, capacities to absorb water, dibutyl phthalate, paraffin oil, particle size distribution, and morphology of particle surface). Precipitation process (its parameters) and heating of the reactive mixture exerts a significant effect on the principal physicochemical properties of the pigments. The heating significantly affects first of all color shade of the obtained silicate and oxide pigments as well as their dispersion. Coprecipitated chromium(III) and iron(III) silicates exhibit a brownish color and a reasonably uniform character. Apart from primary agglomerates (in the range of 414-717 nm), they contain small amounts of secondary agglomerates (in the range of 4154-6445 nm). Best physicochemical parameters have been demonstrated by chromium pigments which have been precipitated from chromium solutions reduced using hydrogen peroxide. Chromium(III) oxides deserve particular distinction since their structure includes primary particles, primary agglomerates but is completely free of secondary agglomerates. The pigments manifest a brightly green color and a low capacity to absorb water (100 cm3 x 100 g(-1)). Application of hydrophobicity-inducing agents in the course of precipitation has corrected physicochemical parameters of both the oxides and silicates of chromium(II). Their bulk densities have been clearly decreased (to as low as below 250 g x L(-1) in the case of chromium(III) silicate), while capacities to absorb paraffin oil have increased to as much as 750 cm3 x 100 g(-1) for chromium(II) oxide. The respective particle size distribution has shown a tendency for disappearance of large accumulations of secondary agglomerates.","Highly dispersed green silicate and oxide pigments precipitated from model systems of postgalvanic waste Abs: A procedure was worked out to obtain highly dispersed green silicate and oxide pigments precipitated from postgalvanic waste. The highly dispersed chromium(III) silicates and oxides were produced from the waste, originating from chromium plating, by reduction of Cr(VI) to Cr(III) employing various reducing agents. All the reductions were conducted in an acidic medium. Solutions of Cr(III), obtained in reducing processes, were employed to precipitate silicate pigments (using sodium metasilicate solution and containing mainly chromium(III) silicates) and oxide pigments (using sodium hydroxide and containing chromium(III) oxides). The precipitated silicates and oxides were subjected to a comprehensive physicochemical analysis (estimating bulk density, capacities to absorb water, dibutyl phthalate, paraffin oil, particle size distribution, and morphology of particle surface). Precipitation process (its parameters) and heating of the reactive mixture exerts a significant effect on the principal physicochemical properties of the pigments. The heating significantly affects first of all color shade of the obtained silicate and oxide pigments as well as their dispersion. Coprecipitated chromium(III) and iron(III) silicates exhibit a brownish color and a reasonably uniform character. Apart from primary agglomerates (in the range of 414-717 nm), they contain small amounts of secondary agglomerates (in the range of 4154-6445 nm). Best physicochemical parameters have been demonstrated by chromium pigments which have been precipitated from chromium solutions reduced using hydrogen peroxide. Chromium(III) oxides deserve particular distinction since their structure includes primary particles, primary agglomerates but is completely free of secondary agglomerates. The pigments manifest a brightly green color and a low capacity to absorb water (100 cm3 x 100 g(-1)). Application of hydrophobicity-inducing agents in the course of precipitation has corrected physicochemical parameters of both the oxides and silicates of chromium(II). Their bulk densities have been clearly decreased (to as low as below 250 g x L(-1) in the case of chromium(III) silicate), while capacities to absorb paraffin oil have increased to as much as 750 cm3 x 100 g(-1) for chromium(II) oxide. The respective particle size distribution has shown a tendency for disappearance of large accumulations of secondary agglomerates."
789261,Brown et al. 2006,Molecular dynamics of the Shewanella oneidensis response to chromate stress,"Temporal genomic profiling and whole-cell proteomic analyses were performed to characterize the dynamic molecular response of the metal-reducing bacterium Shewanella oneidensis MR-1 to an acute chromate shock. The complex dynamics of cellular processes demand the integration of methodologies that describe biological systems at the levels of regulation, gene and protein expression, and metabolite production. Genomic microarray analysis of the transcriptome dynamics of midexponential phase cells subjected to 1 mm potassium chromate (K(2)CrO(4)) at exposure time intervals of 5, 30, 60, and 90 min revealed 910 genes that were differentially expressed at one or more time points. Strongly induced genes included those encoding components of a TonB1 iron transport system (tonB1-exbB1-exbD1), hemin ATP-binding cassette transporters (hmuTUV), TonB-dependent receptors as well as sulfate transporters (cysP, cysW-2, and cysA-2), and enzymes involved in assimilative sulfur metabolism (cysC, cysN, cysD, cysH, cysI, and cysJ). Transcript levels for genes with annotated functions in DNA repair (lexA, recX, recA, recN, dinP, and umuD), cellular detoxification (so1756, so3585, and so3586), and two-component signal transduction systems (so2426) were also significantly up-regulated (p &lt; 0.05) in Cr(VI)-exposed cells relative to untreated cells. By contrast, genes with functions linked to energy metabolism, particularly electron transport (e.g. so0902-03-04, mtrA, omcA, and omcB), showed dramatic temporal alterations in expression with the majority exhibiting repression. Differential proteomics based on multidimensional HPLC-MS/MS was used to complement the transcriptome data, resulting in comparable induction and repression patterns for a subset of corresponding proteins. In total, expression of 2,370 proteins were confidently verified with 624 (26%) of these annotated as hypothetical or conserved hypothetical proteins. The initial response of S. oneidensis to chromate shock appears to require a combination of different regulatory networks that involve genes with annotated functions in oxidative stress protection, detoxification, protein stress protection, iron and sulfur acquisition, and SOS-controlled DNA repair mechanisms.","Molecular dynamics of the Shewanella oneidensis response to chromate stress Abs: Temporal genomic profiling and whole-cell proteomic analyses were performed to characterize the dynamic molecular response of the metal-reducing bacterium Shewanella oneidensis MR-1 to an acute chromate shock. The complex dynamics of cellular processes demand the integration of methodologies that describe biological systems at the levels of regulation, gene and protein expression, and metabolite production. Genomic microarray analysis of the transcriptome dynamics of midexponential phase cells subjected to 1 mm potassium chromate (K(2)CrO(4)) at exposure time intervals of 5, 30, 60, and 90 min revealed 910 genes that were differentially expressed at one or more time points. Strongly induced genes included those encoding components of a TonB1 iron transport system (tonB1-exbB1-exbD1), hemin ATP-binding cassette transporters (hmuTUV), TonB-dependent receptors as well as sulfate transporters (cysP, cysW-2, and cysA-2), and enzymes involved in assimilative sulfur metabolism (cysC, cysN, cysD, cysH, cysI, and cysJ). Transcript levels for genes with annotated functions in DNA repair (lexA, recX, recA, recN, dinP, and umuD), cellular detoxification (so1756, so3585, and so3586), and two-component signal transduction systems (so2426) were also significantly up-regulated (p &lt; 0.05) in Cr(VI)-exposed cells relative to untreated cells. By contrast, genes with functions linked to energy metabolism, particularly electron transport (e.g. so0902-03-04, mtrA, omcA, and omcB), showed dramatic temporal alterations in expression with the majority exhibiting repression. Differential proteomics based on multidimensional HPLC-MS/MS was used to complement the transcriptome data, resulting in comparable induction and repression patterns for a subset of corresponding proteins. In total, expression of 2,370 proteins were confidently verified with 624 (26%) of these annotated as hypothetical or conserved hypothetical proteins. The initial response of S. oneidensis to chromate shock appears to require a combination of different regulatory networks that involve genes with annotated functions in oxidative stress protection, detoxification, protein stress protection, iron and sulfur acquisition, and SOS-controlled DNA repair mechanisms."
787610,Eliason and  Morose 2011,Safer alternatives assessment: The Massachusetts process as a model for state governments,"In 2006 the Massachusetts Toxics Use Reduction Institute conducted a study to determine if states could identify safer alternatives to five chemicals of concern. The chemicals investigated included di (2-ethylhexyl) phthalate (DEHP), formaldehyde, hexavalent chromium, lead and perchloroethylene. First, the Institute developed a methodology for assessing alternatives to these five chemicals that allowed it to quickly determine priority uses and alternatives to assess and to research the pertinent decision criteria, which included performance, technical, financial environmental and human health parameters. The methodology included important feedback from stakeholders in the state, which helped to focus and enhance the value of the work. Second, the Institute implemented the methodology over a ten month period. Based on the activities conducted by the Institute, safer alternatives were identified for each of the priority uses associated with the five chemicals studied. This report summarizes the methodology employed and provides examples of the results for one of the five chemicals, namely DEHP. The experience of the Institute and the information contained in this report indicates that alternatives assessment was a useful approach to organizing and evaluating information about chemicals and alternatives.","Safer alternatives assessment: The Massachusetts process as a model for state governments Abs: In 2006 the Massachusetts Toxics Use Reduction Institute conducted a study to determine if states could identify safer alternatives to five chemicals of concern. The chemicals investigated included di (2-ethylhexyl) phthalate (DEHP), formaldehyde, hexavalent chromium, lead and perchloroethylene. First, the Institute developed a methodology for assessing alternatives to these five chemicals that allowed it to quickly determine priority uses and alternatives to assess and to research the pertinent decision criteria, which included performance, technical, financial environmental and human health parameters. The methodology included important feedback from stakeholders in the state, which helped to focus and enhance the value of the work. Second, the Institute implemented the methodology over a ten month period. Based on the activities conducted by the Institute, safer alternatives were identified for each of the priority uses associated with the five chemicals studied. This report summarizes the methodology employed and provides examples of the results for one of the five chemicals, namely DEHP. The experience of the Institute and the information contained in this report indicates that alternatives assessment was a useful approach to organizing and evaluating information about chemicals and alternatives."
783005,Oberly et al. 1996,An evaluation of the twofold rule for assessing a positive response in the L5178Y TK+/- mouse lymphoma assay,"The L5178Y tk+/- mouse lymphoma assay (MLA) has been in use for more than 15 years as a tool for evaluating the mutagenic potential of various agents. As with other genetic toxicology test systems, one criterion for a positive response has been the requirement of at least a 2-fold increase in mutant frequency (MF) as compared to the respective MF of the solvent controls. More recently, an actual specific increase in MF has been proposed as a criterion for determining a positive response in the MLA; however, this may not be appropriate for laboratories with a low, yet stable, background MF. The twofold rule criterion was evaluated in our laboratory with 66 compounds. The mutagenic status of these compounds was previously determined in other test systems and at one or more laboratories, including Lilly Research Laboratories. The results of this evaluation demonstrate that the twofold rule is an effective method for identifying mutagenic agents in the MLA at LRL where a lower, yet acceptable, background mutation frequency is the norm. A small number of compounds (6) yielded results discordant with the literature; however, these compounds have been previously found to be either difficult to detect in genotoxic assays or to show specific sensitivity in the MLA.","An evaluation of the twofold rule for assessing a positive response in the L5178Y TK+/- mouse lymphoma assay Abs: The L5178Y tk+/- mouse lymphoma assay (MLA) has been in use for more than 15 years as a tool for evaluating the mutagenic potential of various agents. As with other genetic toxicology test systems, one criterion for a positive response has been the requirement of at least a 2-fold increase in mutant frequency (MF) as compared to the respective MF of the solvent controls. More recently, an actual specific increase in MF has been proposed as a criterion for determining a positive response in the MLA; however, this may not be appropriate for laboratories with a low, yet stable, background MF. The twofold rule criterion was evaluated in our laboratory with 66 compounds. The mutagenic status of these compounds was previously determined in other test systems and at one or more laboratories, including Lilly Research Laboratories. The results of this evaluation demonstrate that the twofold rule is an effective method for identifying mutagenic agents in the MLA at LRL where a lower, yet acceptable, background mutation frequency is the norm. A small number of compounds (6) yielded results discordant with the literature; however, these compounds have been previously found to be either difficult to detect in genotoxic assays or to show specific sensitivity in the MLA."
778812,Dierickx 1989,Cytotoxicity testing of 114 compounds by the determination of the protein content in Hep G2 cell cultures,"The cellular protein content measured in cultured Hep G2 cells was used as the endpoint for determining the cytotoxicity of a range of 114 chemical compounds. The relative toxicity of the test compounds was quantified by the determination of the PI(50), which is the concentration of xenobiotic required to produce a 50% reduction in protein content of the culture after 24 hr. Surfactants and heavy metals consistently had low PI(50) values. Hep G2 cells were very sensitive to compounds with more than one carboxyl group. Triacetin and glutathione were identified as false positives. The results suggest that the PI(50) assay could be a useful pre-screening method to test for the cytotoxicity of chemicals.","Cytotoxicity testing of 114 compounds by the determination of the protein content in Hep G2 cell cultures Abs: The cellular protein content measured in cultured Hep G2 cells was used as the endpoint for determining the cytotoxicity of a range of 114 chemical compounds. The relative toxicity of the test compounds was quantified by the determination of the PI(50), which is the concentration of xenobiotic required to produce a 50% reduction in protein content of the culture after 24 hr. Surfactants and heavy metals consistently had low PI(50) values. Hep G2 cells were very sensitive to compounds with more than one carboxyl group. Triacetin and glutathione were identified as false positives. The results suggest that the PI(50) assay could be a useful pre-screening method to test for the cytotoxicity of chemicals."
775092,Venditti * et al. 2000,"A Multidisciplinary Approach to Assess History, Environmental Risks, and Remediation Feasability of Soils Contaminated by Metallurgical Activities. Part A: Chemical and Physical Properties of Metals and Leaching Ability","Three soils contaminated by heavy metals (HMs) and aliphatic hydrocarbons originating from different industrial sources were characterized in a multidisciplinary study combining chemical, physical (Part A), and mineralogical (Part B) approaches to define history, environmental risks, and remediation feasibility. These were an agricultural soil located nearby a Zn/Pb smelter and two soils from a steel metallurgical (siderurgy) waste land. High Pb and Zn contents were reported for all, and high Cr, Cd, and aliphatic hydrocarbons were present in different combinations in two out of three soils. Carbonate matrixes more strongly cemented fine particles in the agricultural soil than in both siderurgical ones, but buffering capacities were stronger in the latter. After the disruption of these cements by ultrasounds, HM were concentrated in the &lt;50-microm fraction of the agricultural and of one siderurgical soil. Sequential extractions indicated for all the soils a preferential association of HM with carbonates, Fe-Mn oxides, organic matter, and sulfides. The stirring of one siderurgical soil with water resulted in an immediate leaching of hexavalent chromium (0.3 mg x L(-1)) involving potential ecotoxicological risks.","A Multidisciplinary Approach to Assess History, Environmental Risks, and Remediation Feasability of Soils Contaminated by Metallurgical Activities. Part A: Chemical and Physical Properties of Metals and Leaching Ability Abs: Three soils contaminated by heavy metals (HMs) and aliphatic hydrocarbons originating from different industrial sources were characterized in a multidisciplinary study combining chemical, physical (Part A), and mineralogical (Part B) approaches to define history, environmental risks, and remediation feasibility. These were an agricultural soil located nearby a Zn/Pb smelter and two soils from a steel metallurgical (siderurgy) waste land. High Pb and Zn contents were reported for all, and high Cr, Cd, and aliphatic hydrocarbons were present in different combinations in two out of three soils. Carbonate matrixes more strongly cemented fine particles in the agricultural soil than in both siderurgical ones, but buffering capacities were stronger in the latter. After the disruption of these cements by ultrasounds, HM were concentrated in the &lt;50-microm fraction of the agricultural and of one siderurgical soil. Sequential extractions indicated for all the soils a preferential association of HM with carbonates, Fe-Mn oxides, organic matter, and sulfides. The stirring of one siderurgical soil with water resulted in an immediate leaching of hexavalent chromium (0.3 mg x L(-1)) involving potential ecotoxicological risks."
772801,Van Der putte et al. 1981,"Effect of pH on uptake, tissue distribution and retention of hexavalent chromium in rainbow trout (Salmo gairdneri)","HEEP COPYRIGHT: BIOL ABS. Uptake, distribution and retention of Cr in rainbow trout (S. gairdneri) was studied after short-term (2-4 days) exposure to 51CrO42--containing Na2CrO4 solutions of different concentrations (2-50 mg/l Cr) and pH (7.8 and 6.5). At pH 7.8, highest contents of Cr were found in gill, liver, kidney and digestive tract of the trout. Cr was not distributed evenly among the different subcellular fractions of the tissues but was concentrated in the nuclear fraction of gill tissue and in the soluble fraction of kidney and liver tissue. Upon transfer of exposed fish to tap-water, Cr was rapidly eliminated from blood, gill and digestive tract. Cr contents remained high in kidney and liver. When the pH was decreased from 7.8 to 6.5, the lethal action of hexavalent Cr increased and a different pattern of accumulation and elimination of Cr was observed. The major differences were found in the gills, which concentrated significantly more Cr at pH 6.5 than at pH 7.8, irrespective of exposure time and concentration. As an ESR signal characteristic for trivalent or pentavalent Cr was detected in gills, the differences must have been partly due to the higher oxidizing action of hexavalent Cr at the lower pH.","Effect of pH on uptake, tissue distribution and retention of hexavalent chromium in rainbow trout (Salmo gairdneri) Abs: HEEP COPYRIGHT: BIOL ABS. Uptake, distribution and retention of Cr in rainbow trout (S. gairdneri) was studied after short-term (2-4 days) exposure to 51CrO42--containing Na2CrO4 solutions of different concentrations (2-50 mg/l Cr) and pH (7.8 and 6.5). At pH 7.8, highest contents of Cr were found in gill, liver, kidney and digestive tract of the trout. Cr was not distributed evenly among the different subcellular fractions of the tissues but was concentrated in the nuclear fraction of gill tissue and in the soluble fraction of kidney and liver tissue. Upon transfer of exposed fish to tap-water, Cr was rapidly eliminated from blood, gill and digestive tract. Cr contents remained high in kidney and liver. When the pH was decreased from 7.8 to 6.5, the lethal action of hexavalent Cr increased and a different pattern of accumulation and elimination of Cr was observed. The major differences were found in the gills, which concentrated significantly more Cr at pH 6.5 than at pH 7.8, irrespective of exposure time and concentration. As an ESR signal characteristic for trivalent or pentavalent Cr was detected in gills, the differences must have been partly due to the higher oxidizing action of hexavalent Cr at the lower pH."
772799,Van Der putte et al. 1981,Effect of pH on the acute toxicity of hexavalent chromium to rainbow trout (Salmo gairdneri),"HEEP COPYRIGHT: BIOL ABS. Acute toxicity of Cr(VI) to rainbow trout (S. gairdneri) increased with decreasing pH in the range 7.8-6.5. Morphological changes that could be associated with acute Cr(VI) poisoning at pH 7.8 were found in gills, kidney and stomach; those at pH 6.5 appeared to be restricted to the gills. At both pH values, similar alterations in plasma osmolality and hematocrit values of blood were found in fish surviving an exposure to acute toxic concentrations. To explain observed effects, hydrochromate (HCrO4-) and chromate (CrO42) were considered as the toxic species of Cr(VI). An attempt was made to calculate the relative toxicities of these ionic species from empirical toxicity relationships for weak acids in fish, as described in the literature.","Effect of pH on the acute toxicity of hexavalent chromium to rainbow trout (Salmo gairdneri) Abs: HEEP COPYRIGHT: BIOL ABS. Acute toxicity of Cr(VI) to rainbow trout (S. gairdneri) increased with decreasing pH in the range 7.8-6.5. Morphological changes that could be associated with acute Cr(VI) poisoning at pH 7.8 were found in gills, kidney and stomach; those at pH 6.5 appeared to be restricted to the gills. At both pH values, similar alterations in plasma osmolality and hematocrit values of blood were found in fish surviving an exposure to acute toxic concentrations. To explain observed effects, hydrochromate (HCrO4-) and chromate (CrO42) were considered as the toxic species of Cr(VI). An attempt was made to calculate the relative toxicities of these ionic species from empirical toxicity relationships for weak acids in fish, as described in the literature."
765727,Hendricks and  Larsen 1966,An evaluation of selected methods of collection and analysis of low concentrations of ozone,"Seven analytical methods for the analysis of low concentrations of ozone (10028156) (O3) were evaluated. A few problems associated with collection of O3 were assessed. One collection method used a short absorption train of granular chromic-acid and potassium-permanganate. This system resulted in a 15 percent loss in an 0.8 parts per million (ppm) ozone gas stream. Silica gel saturated with an 0.4 molar (M) concentration of sodium-dichromate and 0.72M sulfuric-acid in a Schwartz drying tube were used to remove nitrogen-dioxide. A recovery test with a Mylar bag given eight conditional treatments with 2ppm of ozone for 23 hours gave a 75 percent recovery after 90 minutes. The analytical method using potassium-iodide lacked specificity and was reported unsuitable for industrial hygiene investigations. The phenolphthalein method was sensitive, rapid and simple; however, this method also lacked specificity and was judged to be a poor choice for field use. A sodium-diphenylamine-sulfonate method was less subject to interferences than the previous two methods. The method was rapid and simple, but the reagent was expensive and sensitivity was poor. The fluorescein method had excellent sensitivity but standardization and reagent preparation was difficult. An analytical method using 4,4'-dimethoxystilbene was specific, but sensitivity was not satisfactory. There was also difficulty with the corrosive nature and unavailability of reagents. The nitrogen-dioxide equivalent method was sensitive, specific, and rapid, and the color developed was relatively stable. The rubber cracking method was rapid, simple, and relatively specific but less precise. The authors suggest that the rubber cracking method may be useful for preliminary surveys. They recommend the nitrogen-dioxide equivalent method for situations where the ozone concentration remains unchanged during the time of collection and analysis.","An evaluation of selected methods of collection and analysis of low concentrations of ozone Abs: Seven analytical methods for the analysis of low concentrations of ozone (10028156) (O3) were evaluated. A few problems associated with collection of O3 were assessed. One collection method used a short absorption train of granular chromic-acid and potassium-permanganate. This system resulted in a 15 percent loss in an 0.8 parts per million (ppm) ozone gas stream. Silica gel saturated with an 0.4 molar (M) concentration of sodium-dichromate and 0.72M sulfuric-acid in a Schwartz drying tube were used to remove nitrogen-dioxide. A recovery test with a Mylar bag given eight conditional treatments with 2ppm of ozone for 23 hours gave a 75 percent recovery after 90 minutes. The analytical method using potassium-iodide lacked specificity and was reported unsuitable for industrial hygiene investigations. The phenolphthalein method was sensitive, rapid and simple; however, this method also lacked specificity and was judged to be a poor choice for field use. A sodium-diphenylamine-sulfonate method was less subject to interferences than the previous two methods. The method was rapid and simple, but the reagent was expensive and sensitivity was poor. The fluorescein method had excellent sensitivity but standardization and reagent preparation was difficult. An analytical method using 4,4'-dimethoxystilbene was specific, but sensitivity was not satisfactory. There was also difficulty with the corrosive nature and unavailability of reagents. The nitrogen-dioxide equivalent method was sensitive, specific, and rapid, and the color developed was relatively stable. The rubber cracking method was rapid, simple, and relatively specific but less precise. The authors suggest that the rubber cracking method may be useful for preliminary surveys. They recommend the nitrogen-dioxide equivalent method for situations where the ozone concentration remains unchanged during the time of collection and analysis."
765343,Meharg 1994,Industrial accidents involving release of chemicals into the environment: Ecotoxicology,"BIOSIS COPYRIGHT: BIOL ABS. Major industrial accidents pose a serious threat to surrounding habitats. Each accident is unique in terms of pollutants released, pollutant concentrations and pollutant dispersal. The habitats receiving the pollutants are also unique. These factors mean that assessing the environmental and ecological impact of any given pollution event will be complex. Case histories of the biological impact of chemicals released from industrial accidents are reviewed to determine how to assess ecotoxicity of pollutants involved.","Industrial accidents involving release of chemicals into the environment: Ecotoxicology Abs: BIOSIS COPYRIGHT: BIOL ABS. Major industrial accidents pose a serious threat to surrounding habitats. Each accident is unique in terms of pollutants released, pollutant concentrations and pollutant dispersal. The habitats receiving the pollutants are also unique. These factors mean that assessing the environmental and ecological impact of any given pollution event will be complex. Case histories of the biological impact of chemicals released from industrial accidents are reviewed to determine how to assess ecotoxicity of pollutants involved."
759421,Sinha et al. 2010,"Metal accumulation, growth, antioxidants and oil yield of Brassica juncea L. exposed to different metals","In agricultural fields, heavy metal contamination is responsible for limiting the crop productivity and quality. This study reports that the plants of Brassica juncea L. cv. Pusa bold grown on contaminated substrates [Cu, Cr(VI), As(III), As(V)] under simulated field conditions have shown translocation of metals to the upper part and its sequestration in the leaves without significantly affecting on oil yield, except for Cr and higher concentration of As(V), compared to control. Decrease in the oil content in As(V) treated plants was observed in a dose dependent manner; however, maximum decrease was recorded in Cr treated plants. Among all the metal treatments, Cr was the most toxic as evident from the decrease in oil content, growth parameters and antioxidants. The accumulation of metals was below the detection limit in the seeds grown on 10 and 30 mg kg(-1) As(III) and Cr(VI); 10 mg kg(-1) As(V)) and thus can be recommended only for oil cultivation.","Metal accumulation, growth, antioxidants and oil yield of Brassica juncea L. exposed to different metals Abs: In agricultural fields, heavy metal contamination is responsible for limiting the crop productivity and quality. This study reports that the plants of Brassica juncea L. cv. Pusa bold grown on contaminated substrates [Cu, Cr(VI), As(III), As(V)] under simulated field conditions have shown translocation of metals to the upper part and its sequestration in the leaves without significantly affecting on oil yield, except for Cr and higher concentration of As(V), compared to control. Decrease in the oil content in As(V) treated plants was observed in a dose dependent manner; however, maximum decrease was recorded in Cr treated plants. Among all the metal treatments, Cr was the most toxic as evident from the decrease in oil content, growth parameters and antioxidants. The accumulation of metals was below the detection limit in the seeds grown on 10 and 30 mg kg(-1) As(III) and Cr(VI); 10 mg kg(-1) As(V)) and thus can be recommended only for oil cultivation."
758637,Bright et al. 1997,Occupational asthma due to chrome and nickel electroplating,"Exposure to chromium during electroplating is a recognised though poorly characterised cause of occupational asthma. The first series of such patients referred to a specialist occupational lung disease clinic is reported.<br /><br /> The diagnosis of occupational asthma was made from a history of asthma with rest day improvement and confirmed by specific bronchial provocation testing with potassium dichromate and nickel chloride.<br /><br /> Seven workers had been exposed to chrome and nickel fumes from electroplating for eight months to six years before asthma developed. One subject, although exposed for 11 years without symptoms, developed asthma after a single severe exposure during a ventilation failure. This was the only subject who had never smoked. The diagnosis was confirmed by specific bronchial challenges. Two workers had isolated immediate reactions, one a late asthmatic reaction, and four a dual response following exposure to nebulised potassium dichromate at 1-10 mg/ml. Two of the four subjects were also challenged with nebulised nickel chloride at 0.1-10 mg/ml. Two showed isolated late asthmatic reactions, in one at 0.1 mg/ml, where nickel was probably the primary sensitising agent. Four workers carried out two hourly measurements of peak expiratory flow over days at and away from work. All were scored as having occupational asthma using OASYS-2. Breathing zone air monitoring was carried out in 60 workers from four decorative and two hard chrome plating shops from workers with similar jobs to those sensitised. No measurement exceeded the current occupational exposure standard for chromate or nickel, the mean levels of chromate exposure for jobs similar to those of the affected workers were 9-15 micrograms/m3.<br /><br /> Chrome used in electroplating is a potential cause of occupational asthma. Sensitivity to chrome in electroplaters may occur in situations where exposure levels are likely to be within the current exposure standards. There may be cross reactivity with nickel. Inhalation challenge with nebulised potassium dichromate solution is helpful in making the specific diagnosis where doubt exists.","Occupational asthma due to chrome and nickel electroplating Abs: Exposure to chromium during electroplating is a recognised though poorly characterised cause of occupational asthma. The first series of such patients referred to a specialist occupational lung disease clinic is reported.<br /><br /> The diagnosis of occupational asthma was made from a history of asthma with rest day improvement and confirmed by specific bronchial provocation testing with potassium dichromate and nickel chloride.<br /><br /> Seven workers had been exposed to chrome and nickel fumes from electroplating for eight months to six years before asthma developed. One subject, although exposed for 11 years without symptoms, developed asthma after a single severe exposure during a ventilation failure. This was the only subject who had never smoked. The diagnosis was confirmed by specific bronchial challenges. Two workers had isolated immediate reactions, one a late asthmatic reaction, and four a dual response following exposure to nebulised potassium dichromate at 1-10 mg/ml. Two of the four subjects were also challenged with nebulised nickel chloride at 0.1-10 mg/ml. Two showed isolated late asthmatic reactions, in one at 0.1 mg/ml, where nickel was probably the primary sensitising agent. Four workers carried out two hourly measurements of peak expiratory flow over days at and away from work. All were scored as having occupational asthma using OASYS-2. Breathing zone air monitoring was carried out in 60 workers from four decorative and two hard chrome plating shops from workers with similar jobs to those sensitised. No measurement exceeded the current occupational exposure standard for chromate or nickel, the mean levels of chromate exposure for jobs similar to those of the affected workers were 9-15 micrograms/m3.<br /><br /> Chrome used in electroplating is a potential cause of occupational asthma. Sensitivity to chrome in electroplaters may occur in situations where exposure levels are likely to be within the current exposure standards. There may be cross reactivity with nickel. Inhalation challenge with nebulised potassium dichromate solution is helpful in making the specific diagnosis where doubt exists."
758636,Kumar et al. 2005,Semen quality of industrial workers occupationally exposed to chromium,"A total of sixty-one subjects occupationally exposed to chromium in an industry which manufactures chromium sulphate and fifteen control subjects from a nearby industry which does not manufacture any chromium related compounds were studied. The history of each subject was recorded on pre-designed form through interview and a routine medical examination was carried out. Blood samples (5-6 ml) were collected for the estimation of chromium and semen samples were collected for semen analysis and the determination of copper and zinc levels in the seminal plasma. Clinical examination revealed nasal perforation in 10 subjects (out of 61) in the exposed group as compared to none in the control group. A significantly higher level of chromium was observed in the blood of the exposed workers as compared to the control. The concentration of zinc in seminal plasma was lower while the level of copper was higher in the exposed group as compared to the control. However, these changes were not statistically significant. Statistically significant higher numbers of morphologically abnormal sperms were noticed in the exposed group with respect to the control. Further analysis of the data indicated that about 53% of the exposed subjects showed less than 30% normal forms as compared to 10% in control subjects. However, no significant alterations in semen volume, liquefaction time, mean pH value, sperm viability, concentration or motility, were noticed between chromium exposed and unexposed workers. The data also indicates that exposure to chromium has some effect on human sperm as a significant positive correlation (r=0.301) was observed between percentages of abnormal sperm morphology and blood chromium levels (p=0.016) after pooling all the data of the control and exposure groups.","Semen quality of industrial workers occupationally exposed to chromium Abs: A total of sixty-one subjects occupationally exposed to chromium in an industry which manufactures chromium sulphate and fifteen control subjects from a nearby industry which does not manufacture any chromium related compounds were studied. The history of each subject was recorded on pre-designed form through interview and a routine medical examination was carried out. Blood samples (5-6 ml) were collected for the estimation of chromium and semen samples were collected for semen analysis and the determination of copper and zinc levels in the seminal plasma. Clinical examination revealed nasal perforation in 10 subjects (out of 61) in the exposed group as compared to none in the control group. A significantly higher level of chromium was observed in the blood of the exposed workers as compared to the control. The concentration of zinc in seminal plasma was lower while the level of copper was higher in the exposed group as compared to the control. However, these changes were not statistically significant. Statistically significant higher numbers of morphologically abnormal sperms were noticed in the exposed group with respect to the control. Further analysis of the data indicated that about 53% of the exposed subjects showed less than 30% normal forms as compared to 10% in control subjects. However, no significant alterations in semen volume, liquefaction time, mean pH value, sperm viability, concentration or motility, were noticed between chromium exposed and unexposed workers. The data also indicates that exposure to chromium has some effect on human sperm as a significant positive correlation (r=0.301) was observed between percentages of abnormal sperm morphology and blood chromium levels (p=0.016) after pooling all the data of the control and exposure groups."
758635,Kitamura et al. 2003,Increase of olfactory threshold in plating factory workers exposed to chromium in Korea,"To disclose the effects of chromium (Cr) on olfactory function, olfactory threshold tests were conducted on 27 male plating workers (Cr workers) with signs and symptoms of olfactory irritation but without nasal septum perforation or ulcer and on 34 male control subjects in Korean plating factories. The Cr workers had been exposed to Cr fume for 0.9 to 18.2 (mean 7.9) years; their blood Cr concentrations (0.16-3.69, mean 1.29 microg/dl) were significantly higher than those of the 34 control subjects (0.04-1.95, mean 0.55 microg/dl). Scores on recognition thresholds among the Cr workers were significantly higher than those of the control subjects (p < 0.05) and related positively and significantly to the exposure periods of the 27 Cr workers (p < 0.05). Olfactory thresholds were not significantly different between the Cr workers with and without nasal signs or symptoms, except that the scores on the recognition threshold were significantly higher in those experiencing difficulty with smell (p < 0.05). It is suggested that olfactory threshold is affected by Cr without development of nasal septum perforation or ulceration.","Increase of olfactory threshold in plating factory workers exposed to chromium in Korea Abs: To disclose the effects of chromium (Cr) on olfactory function, olfactory threshold tests were conducted on 27 male plating workers (Cr workers) with signs and symptoms of olfactory irritation but without nasal septum perforation or ulcer and on 34 male control subjects in Korean plating factories. The Cr workers had been exposed to Cr fume for 0.9 to 18.2 (mean 7.9) years; their blood Cr concentrations (0.16-3.69, mean 1.29 microg/dl) were significantly higher than those of the 34 control subjects (0.04-1.95, mean 0.55 microg/dl). Scores on recognition thresholds among the Cr workers were significantly higher than those of the control subjects (p < 0.05) and related positively and significantly to the exposure periods of the 27 Cr workers (p < 0.05). Olfactory thresholds were not significantly different between the Cr workers with and without nasal signs or symptoms, except that the scores on the recognition threshold were significantly higher in those experiencing difficulty with smell (p < 0.05). It is suggested that olfactory threshold is affected by Cr without development of nasal septum perforation or ulceration."
758634,Kornhauser et al. 2002,Possible adverse effect of chromium in occupational exposure of tannery workers,"Our aim was to investigate the adverse effects of occupational exposure to trivalent chromium. We measured chromium and iron levels in serum and urine and hemoglobin levels in tannery workers and unexposed persons. We studied three groups of subjects. Group 1 included 15 non-smoking male tannery workers highly exposed to chromium from tanning and retanning departments. Group 2 included 14 non-smoking male tannery workers with moderate chromium exposure from dying, drying and finishing departments. Group 3 included 11 healthy, non-smoking male subjects without direct chromium exposure. Higher serum chromium levels were observed in groups 1 and 2 with respect to group 3 (mean values respectively: 0.43; 0.25 and 0.13 microg x l(-1)). Urine chromium levels in group 1 were higher than those in controls (mean values: 1.78 and 1.35 microg x l(-1)). In group 1 an inverse association was found between serum chromium and urine iron (-0.524), urine chromium and hemoglobin (-0.594) and between the urine chromium to iron ratio and hemoglobin (-0.693, p<0.05). The results suggest a chromium adverse effect on iron metabolism, possibly associated with excessive body chromium accumulation. In conclusion, chromium urine test could be recommended for diagnosis of chromium adverse effect on iron metabolism. Further studies are needed to quantify the relationship between urine chromium and hemoglobin metabolism.","Possible adverse effect of chromium in occupational exposure of tannery workers Abs: Our aim was to investigate the adverse effects of occupational exposure to trivalent chromium. We measured chromium and iron levels in serum and urine and hemoglobin levels in tannery workers and unexposed persons. We studied three groups of subjects. Group 1 included 15 non-smoking male tannery workers highly exposed to chromium from tanning and retanning departments. Group 2 included 14 non-smoking male tannery workers with moderate chromium exposure from dying, drying and finishing departments. Group 3 included 11 healthy, non-smoking male subjects without direct chromium exposure. Higher serum chromium levels were observed in groups 1 and 2 with respect to group 3 (mean values respectively: 0.43; 0.25 and 0.13 microg x l(-1)). Urine chromium levels in group 1 were higher than those in controls (mean values: 1.78 and 1.35 microg x l(-1)). In group 1 an inverse association was found between serum chromium and urine iron (-0.524), urine chromium and hemoglobin (-0.594) and between the urine chromium to iron ratio and hemoglobin (-0.693, p<0.05). The results suggest a chromium adverse effect on iron metabolism, possibly associated with excessive body chromium accumulation. In conclusion, chromium urine test could be recommended for diagnosis of chromium adverse effect on iron metabolism. Further studies are needed to quantify the relationship between urine chromium and hemoglobin metabolism."
758633,Li et al. 2001,Effect of Cr(VI) exposure on sperm quality: human and animal studies,"The semen status of male workers occupationally exposed to hexavalent chromium(VI) was investigated. Sperm counts from exposed workers were 47.05+/-2.13 x 10(6)/ml and those from control group 88.96+/-3.40 x 10(6)/ml. Sperm motility decreased from 81.92+/-0.41% for the control group to 69.71+/-0.93% for the exposed workers. The levels of zinc, lactate dehydrogenase (LDH), and lactate dehydrogenase C4 isoenzyme (LDH-x) in seminal plasma for the exposed workers were 1.48+/-0.07 micromol/ml, 1.05+/-0.02 x 10(3) U, and 0.47+/-0.01 x 10(3) U, respectively, which were significantly lower than those of 5.72+/-0.15 micromol/ml, 1.49+/-0.02 x 10(3) U, and 0.78+/-0.15 x 10(3) U for the control group, respectively. Follicle stimulating hormone (FSH) (7.34+/-0.34 x 10(-3) IU/ml) in serum from the exposed workers was significantly higher than that (2.41+/-0.08 x 10(-3) IU/ml) from the control group. On the other hand, there were no significant differences in semen volume, semen liquefaction time, luteinizing hormone (LH) level in serum, and Cr concentration in both serum and seminal plasma between the exposed workers and the control group. Feeding Cr(VI) to rats significantly reduced the epididymal sperm counts from 87.40+/-3.85 x 10(6)/g epididymis in control group to 21.40+/-1.20 x 10(6)/g epididymis at a CrO(3) dose of 10 mg/kg body weight and to 17.48+/-1.04 x 10(6)/g epididymis at a CrO(3) dose of 20 mg/kg body weight. Exposure of rats to Cr(VI) also significantly increased the sperm abnormality from 2.75+/-0.06% in the control group to 6.68+/-0.32% in the exposed group at a CrO(3) dose of 10 mg/kg body and to 7.6+/-0.15% at a CrO(3) dose of 20 mg/kg body weight. In exposed rats, there was visible disruption in germ cell arrangement near the walls of the seminiferous tubules. The diameters of seminiferous tubules in exposed rats were smaller. These results suggest that occupational exposure to chromium(VI) leads to alteration of semen status and may affect the reproductive success of exposed workers.","Effect of Cr(VI) exposure on sperm quality: human and animal studies Abs: The semen status of male workers occupationally exposed to hexavalent chromium(VI) was investigated. Sperm counts from exposed workers were 47.05+/-2.13 x 10(6)/ml and those from control group 88.96+/-3.40 x 10(6)/ml. Sperm motility decreased from 81.92+/-0.41% for the control group to 69.71+/-0.93% for the exposed workers. The levels of zinc, lactate dehydrogenase (LDH), and lactate dehydrogenase C4 isoenzyme (LDH-x) in seminal plasma for the exposed workers were 1.48+/-0.07 micromol/ml, 1.05+/-0.02 x 10(3) U, and 0.47+/-0.01 x 10(3) U, respectively, which were significantly lower than those of 5.72+/-0.15 micromol/ml, 1.49+/-0.02 x 10(3) U, and 0.78+/-0.15 x 10(3) U for the control group, respectively. Follicle stimulating hormone (FSH) (7.34+/-0.34 x 10(-3) IU/ml) in serum from the exposed workers was significantly higher than that (2.41+/-0.08 x 10(-3) IU/ml) from the control group. On the other hand, there were no significant differences in semen volume, semen liquefaction time, luteinizing hormone (LH) level in serum, and Cr concentration in both serum and seminal plasma between the exposed workers and the control group. Feeding Cr(VI) to rats significantly reduced the epididymal sperm counts from 87.40+/-3.85 x 10(6)/g epididymis in control group to 21.40+/-1.20 x 10(6)/g epididymis at a CrO(3) dose of 10 mg/kg body weight and to 17.48+/-1.04 x 10(6)/g epididymis at a CrO(3) dose of 20 mg/kg body weight. Exposure of rats to Cr(VI) also significantly increased the sperm abnormality from 2.75+/-0.06% in the control group to 6.68+/-0.32% in the exposed group at a CrO(3) dose of 10 mg/kg body and to 7.6+/-0.15% at a CrO(3) dose of 20 mg/kg body weight. In exposed rats, there was visible disruption in germ cell arrangement near the walls of the seminiferous tubules. The diameters of seminiferous tubules in exposed rats were smaller. These results suggest that occupational exposure to chromium(VI) leads to alteration of semen status and may affect the reproductive success of exposed workers."
758632,Liu et al. 1998,Urinary N-acetyl-beta-glucosaminidase as an indicator of renal dysfunction in electroplating workers,"To investigate chromium-induced renal dysfunction in electroplating workers.<br /><br /> A cross-sectional study was used to evaluate four biochemical markers of renal function. A total of 178 workers were divided into 3 comparable groups consisting of 34 hard-chrome plating workers, 98 nickel-chrome electroplating workers. and 46 aluminum anode-oxidation workers, who represented the reference group. Ambient and biological monitoring of urinary chromium were performed to measure exposure concentrations.<br /><br /> Overall, urinary chromium concentrations were highest among hard-chrome plating workers (geometric mean 2.44 microg/g creatinine), followed by nickel-chrome electroplating workers (0.31 microg/g creatinine) and aluminum workers (0.09 microg/g creatinine). Airborne chromium concentrations were also highest in the hard-chrome plating area (geometric mean 4.20 microg/m3), followed by the nickel-chrome electroplating area (0.58 microg/m3) and the aluminum area (0.43 microg/m3). A positive correlation was found between urinary chromium and airborne concentrations (r=0.54, P &lt; 0.01). Urinary concentrations of N-acetyl-beta-D-glucosaminidase (NAG) were also highest among hard-chrome plating workers (geometric mean 4.9 IU/g creatinine), followed by nickel-chrome workers (3.4 IU/g creatinine) and aluminum workers (2.9 IU/g creatinine). The prevalence of &quot;elevated&quot; NAG (&gt;7 IU/g creatinine) was significantly highest among hard-chrome plating workers (23.5%), then among nickel-chrome workers (7.1%) and aluminum workers (8.7%). Differences in beta2-microglobulin, total protein, and microalbumin were not significant.<br /><br /> The author's evidence indicates that NAG is an early indicator of renal dysfunction in hard-chrome plating workers.","Urinary N-acetyl-beta-glucosaminidase as an indicator of renal dysfunction in electroplating workers Abs: To investigate chromium-induced renal dysfunction in electroplating workers.<br /><br /> A cross-sectional study was used to evaluate four biochemical markers of renal function. A total of 178 workers were divided into 3 comparable groups consisting of 34 hard-chrome plating workers, 98 nickel-chrome electroplating workers. and 46 aluminum anode-oxidation workers, who represented the reference group. Ambient and biological monitoring of urinary chromium were performed to measure exposure concentrations.<br /><br /> Overall, urinary chromium concentrations were highest among hard-chrome plating workers (geometric mean 2.44 microg/g creatinine), followed by nickel-chrome electroplating workers (0.31 microg/g creatinine) and aluminum workers (0.09 microg/g creatinine). Airborne chromium concentrations were also highest in the hard-chrome plating area (geometric mean 4.20 microg/m3), followed by the nickel-chrome electroplating area (0.58 microg/m3) and the aluminum area (0.43 microg/m3). A positive correlation was found between urinary chromium and airborne concentrations (r=0.54, P &lt; 0.01). Urinary concentrations of N-acetyl-beta-D-glucosaminidase (NAG) were also highest among hard-chrome plating workers (geometric mean 4.9 IU/g creatinine), followed by nickel-chrome workers (3.4 IU/g creatinine) and aluminum workers (2.9 IU/g creatinine). The prevalence of &quot;elevated&quot; NAG (&gt;7 IU/g creatinine) was significantly highest among hard-chrome plating workers (23.5%), then among nickel-chrome workers (7.1%) and aluminum workers (8.7%). Differences in beta2-microglobulin, total protein, and microalbumin were not significant.<br /><br /> The author's evidence indicates that NAG is an early indicator of renal dysfunction in hard-chrome plating workers."
758630,Rosenman and  Stanbury 1996,Risk of lung cancer among former chromium smelter workers,"Hexavalent chromium is a known carcinogen. Previous epidemiologic studies in the 1950s of United States workers from seven facilities producing chromium compounds from chromite ore have reported a markedly increased risk for dying from lung cancer. As part of a high risk notification project of workers from four of these facilities, a mortality study was performed. The cohort was assembled in 1990-1991 from the Social Security records of four former chromate producing facilities in northern New Jersey. The study subjects were known to have worked at these facilities some time between 1937 and 1971. Proportionate mortality and proportionate cancer mortality ratios (PCMR) were calculated. The overall risk for lung cancer was a PCMR of 1.51 (confidence limits [CL] 1.29-1.74) for white men and 1.34 (CL 1.00-1.75) for black men. These risks increased with increasing duration of employment and latency since time of first employment. The PCMR for greater than 20 years duration of work and more than 20 years since first exposure was 1.94 (CL 1.15-3.06) for white men and 3.08 (CL 1.13-6.71) for black men. The risk for lung cancer for white men remains elevated more than 20 years after exposure has ceased (PCMR, 1.29; CL 1.03-1.60). The PCMR for nasal cavity/sinus cancer was also found to be a significantly increased, 5.18 (CL 2.37-11.30). A cluster of bladder cancer was seen among black workers from one facility, (PCMR, 3.30; CL 1.42-6.51). Despite the cessation of exposure, former chromium workers remain at significantly increased risk of lung cancer. Although there have been case reports of nasal cavity/ sinus cancer in association with chromium exposure, this is the first epidemiologic study to report a significant increase in these cancers. Limitations in this study include lack of exposure data and lack of information on smoking habits. The lack of increase in other smoking-related diseases besides lung cancer indicates that the increase in lung cancer cannot be attributed to cigarette smoking. The ongoing elevated risk of lung cancer after cessation of exposure emphasizes the need for developing early detection texts for lung cancer.","Risk of lung cancer among former chromium smelter workers Abs: Hexavalent chromium is a known carcinogen. Previous epidemiologic studies in the 1950s of United States workers from seven facilities producing chromium compounds from chromite ore have reported a markedly increased risk for dying from lung cancer. As part of a high risk notification project of workers from four of these facilities, a mortality study was performed. The cohort was assembled in 1990-1991 from the Social Security records of four former chromate producing facilities in northern New Jersey. The study subjects were known to have worked at these facilities some time between 1937 and 1971. Proportionate mortality and proportionate cancer mortality ratios (PCMR) were calculated. The overall risk for lung cancer was a PCMR of 1.51 (confidence limits [CL] 1.29-1.74) for white men and 1.34 (CL 1.00-1.75) for black men. These risks increased with increasing duration of employment and latency since time of first employment. The PCMR for greater than 20 years duration of work and more than 20 years since first exposure was 1.94 (CL 1.15-3.06) for white men and 3.08 (CL 1.13-6.71) for black men. The risk for lung cancer for white men remains elevated more than 20 years after exposure has ceased (PCMR, 1.29; CL 1.03-1.60). The PCMR for nasal cavity/sinus cancer was also found to be a significantly increased, 5.18 (CL 2.37-11.30). A cluster of bladder cancer was seen among black workers from one facility, (PCMR, 3.30; CL 1.42-6.51). Despite the cessation of exposure, former chromium workers remain at significantly increased risk of lung cancer. Although there have been case reports of nasal cavity/ sinus cancer in association with chromium exposure, this is the first epidemiologic study to report a significant increase in these cancers. Limitations in this study include lack of exposure data and lack of information on smoking habits. The lack of increase in other smoking-related diseases besides lung cancer indicates that the increase in lung cancer cannot be attributed to cigarette smoking. The ongoing elevated risk of lung cancer after cessation of exposure emphasizes the need for developing early detection texts for lung cancer."
758628,Moulin et al. 1993,Mortality from lung cancer and cardiovascular diseases among stainless-steel producing workers,"The mortality pattern of workers involved in the production of stainless steel (SS) was studied from 1968 to 1984 in order to investigate a possible risk of lung cancer in relation to exposure to chromium compounds, polycyclic aromatic hydrocarbons, and silica. The role of heat exposure in mortality from cardiovascular diseases also was examined. The cohort was comprised of 4,227 workers. Complete individual job histories were provided by the company (UGINE SA). The smoking habits of 24 percent of the cohort members were known from the interview of workers still active during the data collection. The observed numbers of deaths were compared with the expected ones based on national rates with adjustment for age, sex, and calendar time (standardized mortality ratio, SMR). No significant excesses of lung cancer were observed among workers employed in the manufacture of ferroalloys (SMR = 0.68) and in the melting and casting of SS (SMR = 1.04), whereas a significant excess appeared among SS foundry workers (SMR = 2.29). This excess was higher and remained significant among workers with more than 30 years since first employment in the foundry area (SMR = 3.34). Among subjects exposed to heat, no excess was observed for all cardiovascular diseases or for ischemic heart diseases.","Mortality from lung cancer and cardiovascular diseases among stainless-steel producing workers Abs: The mortality pattern of workers involved in the production of stainless steel (SS) was studied from 1968 to 1984 in order to investigate a possible risk of lung cancer in relation to exposure to chromium compounds, polycyclic aromatic hydrocarbons, and silica. The role of heat exposure in mortality from cardiovascular diseases also was examined. The cohort was comprised of 4,227 workers. Complete individual job histories were provided by the company (UGINE SA). The smoking habits of 24 percent of the cohort members were known from the interview of workers still active during the data collection. The observed numbers of deaths were compared with the expected ones based on national rates with adjustment for age, sex, and calendar time (standardized mortality ratio, SMR). No significant excesses of lung cancer were observed among workers employed in the manufacture of ferroalloys (SMR = 0.68) and in the melting and casting of SS (SMR = 1.04), whereas a significant excess appeared among SS foundry workers (SMR = 2.29). This excess was higher and remained significant among workers with more than 30 years since first employment in the foundry area (SMR = 3.34). Among subjects exposed to heat, no excess was observed for all cardiovascular diseases or for ischemic heart diseases."
758604,Boiano et al. 2000,Comparison of three sampling and analytical methods for the determination of airborne hexavalent chromium,"A field study was conducted with the goal of comparing the performance of three recently developed or modified sampling and analytical methods for the determination of airborne hexavalent chromium (Cr(VI)). The study was carried out in a hard chrome electroplating facility and in a jet engine manufacturing facility where airborne Cr(VI) was expected to be present. The analytical methods evaluated included two laboratory-based procedures (OSHA Method ID-215 and NIOSH Method 7605) and a field-portable method (NIOSH Method 7703). These three methods employ an identical sampling methodology: collection of Cr(VI)-containing aerosol on a polyvinyl chloride (PVC) filter housed in a sampling cassette, which is connected to a personal sampling pump calibrated at an appropriate flow rate. The basis of the analytical methods for all three methods involves extraction of the PVC filter in alkaline buffer solution, chemical isolation of the Cr(VI) ion, complexation of the Cr(VI) ion with 1,5-diphenylcarbazide, and spectrometric measurement of the violet chromium diphenylcarbazone complex at 540 nm. However, there are notable specific differences within the sample preparation procedures used in three methods. To assess the comparability of the three measurement protocols, a total of 20 side-by-side air samples were collected, equally divided between a chromic acid electroplating operation and a spray paint operation where water soluble forms of Cr(VI) were used. A range of Cr(VI) concentrations from 0.6 to 960 microg m(-3), with Cr(VI) mass loadings ranging from 0.4 to 32 microg, was measured at the two operations. The equivalence of the means of the log-transformed Cr(VI) concentrations obtained from the different analytical methods was compared. Based on analysis of variance (ANOVA) results, no statistically significant differences were observed between mean values measured using each of the three methods. Small but statistically significant differences were observed between results obtained from performance evaluation samples for the NIOSH field method and the OSHA laboratory method.","Comparison of three sampling and analytical methods for the determination of airborne hexavalent chromium Abs: A field study was conducted with the goal of comparing the performance of three recently developed or modified sampling and analytical methods for the determination of airborne hexavalent chromium (Cr(VI)). The study was carried out in a hard chrome electroplating facility and in a jet engine manufacturing facility where airborne Cr(VI) was expected to be present. The analytical methods evaluated included two laboratory-based procedures (OSHA Method ID-215 and NIOSH Method 7605) and a field-portable method (NIOSH Method 7703). These three methods employ an identical sampling methodology: collection of Cr(VI)-containing aerosol on a polyvinyl chloride (PVC) filter housed in a sampling cassette, which is connected to a personal sampling pump calibrated at an appropriate flow rate. The basis of the analytical methods for all three methods involves extraction of the PVC filter in alkaline buffer solution, chemical isolation of the Cr(VI) ion, complexation of the Cr(VI) ion with 1,5-diphenylcarbazide, and spectrometric measurement of the violet chromium diphenylcarbazone complex at 540 nm. However, there are notable specific differences within the sample preparation procedures used in three methods. To assess the comparability of the three measurement protocols, a total of 20 side-by-side air samples were collected, equally divided between a chromic acid electroplating operation and a spray paint operation where water soluble forms of Cr(VI) were used. A range of Cr(VI) concentrations from 0.6 to 960 microg m(-3), with Cr(VI) mass loadings ranging from 0.4 to 32 microg, was measured at the two operations. The equivalence of the means of the log-transformed Cr(VI) concentrations obtained from the different analytical methods was compared. Based on analysis of variance (ANOVA) results, no statistically significant differences were observed between mean values measured using each of the three methods. Small but statistically significant differences were observed between results obtained from performance evaluation samples for the NIOSH field method and the OSHA laboratory method."
758321,Sora et al. 1986,Disomic and diploid meiotic products induced in Saccharomyces cerevisiae by the salts of 27 elements,"The effects of salts of 27 elements on recombination and on the production of disomic and/or diploid spores during meiosis of Saccharomyces cerevisiae has been investigated. Be(NO3)2, MgSO4, FeSO4, CuSO4, AgNO3, Na2HAsO4 were inactive on the events studied during meiotic cell division. AuCl4, CdCl2, C4H6O4Pb, SnCl2, K2Cr2O7, RbCl induced both disomic and diploid spores. LiCl acted similarly and also affected recombination. Activity in the induction of disomic spores was shown by MnSO4, HgCl2 and SrCl2. CsCl, CaCl2, Na2MoO4, NiCl2, K2PtCl4 increased the frequency of diploid spores, while NaWO4, VOSO4, KCl, BaCl2 already increased recombination frequency. NaBiO3 showed an effect on meiotic recombination only. A decrease in the occurrence of both diploid and disomic spores was suggested by the data obtained with CoCl2.","Disomic and diploid meiotic products induced in Saccharomyces cerevisiae by the salts of 27 elements Abs: The effects of salts of 27 elements on recombination and on the production of disomic and/or diploid spores during meiosis of Saccharomyces cerevisiae has been investigated. Be(NO3)2, MgSO4, FeSO4, CuSO4, AgNO3, Na2HAsO4 were inactive on the events studied during meiotic cell division. AuCl4, CdCl2, C4H6O4Pb, SnCl2, K2Cr2O7, RbCl induced both disomic and diploid spores. LiCl acted similarly and also affected recombination. Activity in the induction of disomic spores was shown by MnSO4, HgCl2 and SrCl2. CsCl, CaCl2, Na2MoO4, NiCl2, K2PtCl4 increased the frequency of diploid spores, while NaWO4, VOSO4, KCl, BaCl2 already increased recombination frequency. NaBiO3 showed an effect on meiotic recombination only. A decrease in the occurrence of both diploid and disomic spores was suggested by the data obtained with CoCl2."
757476,Bardiya and  Bae 2005,Bioremediation potential of a perchlorate-enriched sewage sludge consortium,"The purpose of this work was to explore the reductive bioremediation potential of a perchlorate-enriched facultative anaerobic consortium. Rapid perchlorate reduction and bacterial growth were observed up to 1.84 g l(-1) of perchlorate, but not at 3.82 g l(-1) due to the toxicity. The specific growth rate of the mixed consortium was 0.1 h(-1). The consortium co-reduced perchlorate and nitrate with acetate as e- donor and carbon source. The presence of nitrate slowed down the perchlorate reduction rate. The other e- acceptors utilized include oxygen, chlorate, Cr(VI), and selenate. Over 95% of the 16 mg l(-1) of added Cr(VI) was reduced within 24 h of incubation with a high-density perchlorate-grown consortium. However, the consortium failed to couple growth with reduction of nitrite, sulfate, thiosulfate, and sulfite. During the search for autotrophic perchlorate reduction, many consortia from very diverse natural sources could not use sulfur compounds such as thiosulfate as e- donor.","Bioremediation potential of a perchlorate-enriched sewage sludge consortium Abs: The purpose of this work was to explore the reductive bioremediation potential of a perchlorate-enriched facultative anaerobic consortium. Rapid perchlorate reduction and bacterial growth were observed up to 1.84 g l(-1) of perchlorate, but not at 3.82 g l(-1) due to the toxicity. The specific growth rate of the mixed consortium was 0.1 h(-1). The consortium co-reduced perchlorate and nitrate with acetate as e- donor and carbon source. The presence of nitrate slowed down the perchlorate reduction rate. The other e- acceptors utilized include oxygen, chlorate, Cr(VI), and selenate. Over 95% of the 16 mg l(-1) of added Cr(VI) was reduced within 24 h of incubation with a high-density perchlorate-grown consortium. However, the consortium failed to couple growth with reduction of nitrite, sulfate, thiosulfate, and sulfite. During the search for autotrophic perchlorate reduction, many consortia from very diverse natural sources could not use sulfur compounds such as thiosulfate as e- donor."
757107,Du and  Espenson 2006,"Kinetics of the reaction of chromium(VI) with tris(1,10-phenanthroline)iron(II) ions in acidic solutions. Anion and medium effects: perchlorate versus triflate","Reinvestigation of the reaction between title reagents in aqueous acidic triflate and perchlorate media revealed an unusual difference: the reaction is strictly first-order with respect to the concentration of Fe(phen)3(2+) (phen = 1,10-phenanthroline) in the triflate medium but shows an additional, but we believe artifactual, higher-order term in the perchlorate medium. We postulate that the apparent orders with respect to [Fe(phen)3(2+)] in (H/Li)ClO4 do not indicate the actual chemical mechanism but, in whole or in part, the orders, particularly the higher-order component, reflect an interaction specific to Fe(phen)3(2+) or Fe(phen)3(3+) and ClO4(-) in solution. Data in (H/Li)O3SCF3 solutions indicate that, in the absence of added Fe(phen)3(3+), the first of the three sequential electron-transfer steps is rate controlling. Reactions started in the presence of the product Fe(phen)3(3+) occur somewhat more slowly, suggesting the first electron transfer is reversible. This finding allows the relative rate constants for Cr(V) oxidation and reduction to be evaluated, with limited precision, by two methods of analysis. The dependences on [Cr(VI)] can be resolved into contributions from the species HCrO4(-) and Cr2O7(2-), each of which in turn depends on [H+]. The reaction mechanism is discussed in light of the data obtained in the triflate medium. Further, the rate constants for certain steps can be considered in light of E0 for the Cr(VI)/(V) couple.","Kinetics of the reaction of chromium(VI) with tris(1,10-phenanthroline)iron(II) ions in acidic solutions. Anion and medium effects: perchlorate versus triflate Abs: Reinvestigation of the reaction between title reagents in aqueous acidic triflate and perchlorate media revealed an unusual difference: the reaction is strictly first-order with respect to the concentration of Fe(phen)3(2+) (phen = 1,10-phenanthroline) in the triflate medium but shows an additional, but we believe artifactual, higher-order term in the perchlorate medium. We postulate that the apparent orders with respect to [Fe(phen)3(2+)] in (H/Li)ClO4 do not indicate the actual chemical mechanism but, in whole or in part, the orders, particularly the higher-order component, reflect an interaction specific to Fe(phen)3(2+) or Fe(phen)3(3+) and ClO4(-) in solution. Data in (H/Li)O3SCF3 solutions indicate that, in the absence of added Fe(phen)3(3+), the first of the three sequential electron-transfer steps is rate controlling. Reactions started in the presence of the product Fe(phen)3(3+) occur somewhat more slowly, suggesting the first electron transfer is reversible. This finding allows the relative rate constants for Cr(V) oxidation and reduction to be evaluated, with limited precision, by two methods of analysis. The dependences on [Cr(VI)] can be resolved into contributions from the species HCrO4(-) and Cr2O7(2-), each of which in turn depends on [H+]. The reaction mechanism is discussed in light of the data obtained in the triflate medium. Further, the rate constants for certain steps can be considered in light of E0 for the Cr(VI)/(V) couple."
757019,Sorensen et al. 2006,Acute and chronic activity of perchlorate and hexavalent chromium contamination on the survival and development of Culex quinquefasciatus Say (Diptera: Culicidae),"Effects of water contamination with perchlorate and hexavalent chromium [Cr (VI)] on the mosquito Culex quinquefasciatus were assessed. The chronic (10-day) LC50s values for perchlorate and chromium were 74+/-8.0 mg/L and 0.41+/-0.15 mg/L, respectively. Relative Growth Index, a measure of growth and mortality rates in a population, was significantly reduced within 5 days for levels of perchlorate as low as 25 mg/L and for levels of chromium as low as 0.16 mg/L. Neither compound altered wing length of surviving adults. In combination, contaminants were synergistic, causing 14% more mortality than predicted. Acute (24-h) LC50 values for perchlorate and Cr (VI) were 17,000+/-3200 and 38+/-1.3 mg/L, respectively. Effects on mosquito larvae in contaminated environments are likely to be observed for Cr (VI) but not for perchlorate, which generally does not occur at levels as high as those shown here to affect larval mosquitoes.","Acute and chronic activity of perchlorate and hexavalent chromium contamination on the survival and development of Culex quinquefasciatus Say (Diptera: Culicidae) Abs: Effects of water contamination with perchlorate and hexavalent chromium [Cr (VI)] on the mosquito Culex quinquefasciatus were assessed. The chronic (10-day) LC50s values for perchlorate and chromium were 74+/-8.0 mg/L and 0.41+/-0.15 mg/L, respectively. Relative Growth Index, a measure of growth and mortality rates in a population, was significantly reduced within 5 days for levels of perchlorate as low as 25 mg/L and for levels of chromium as low as 0.16 mg/L. Neither compound altered wing length of surviving adults. In combination, contaminants were synergistic, causing 14% more mortality than predicted. Acute (24-h) LC50 values for perchlorate and Cr (VI) were 17,000+/-3200 and 38+/-1.3 mg/L, respectively. Effects on mosquito larvae in contaminated environments are likely to be observed for Cr (VI) but not for perchlorate, which generally does not occur at levels as high as those shown here to affect larval mosquitoes."
756320,Sorensen et al. 2009,Effects of pollutant accumulation by the invasive weed saltcedar (Tamarix ramosissima) on the biological control agent Diorhabda elongata (Coleoptera: Chrysomelidae),"Hydroponic greenhouse studies were used to investigate the effect of four anthropogenic pollutants (perchlorate (ClO4(-)), selenium (Se), manganese (Mn), and hexavalent chromium (Cr (VI))) on the biological control agent Diorhabda elongata Brullé. Contaminant concentrations were quantified for experimental Tamarix ramosissima Ledab. plants and D. elongata beetles. Growth of larvae was significantly reduced by Se contamination, but was not affected by the presence of perchlorate, Mn, or Cr (VI). All of the contaminants were transferred from plants to D. elongata beetles. Only Cr (VI) was accumulated at greater levels in beetles than in their food. Because T. ramosissima grows in disturbed areas, acquires salts readily, and utilizes groundwater, this plant is likely to accumulate anthropogenic pollutants in contaminated areas. This study is one of the first to investigate the potential of an anthropogenic pollutant to influence a weed biological control system.","Effects of pollutant accumulation by the invasive weed saltcedar (Tamarix ramosissima) on the biological control agent Diorhabda elongata (Coleoptera: Chrysomelidae) Abs: Hydroponic greenhouse studies were used to investigate the effect of four anthropogenic pollutants (perchlorate (ClO4(-)), selenium (Se), manganese (Mn), and hexavalent chromium (Cr (VI))) on the biological control agent Diorhabda elongata Brullé. Contaminant concentrations were quantified for experimental Tamarix ramosissima Ledab. plants and D. elongata beetles. Growth of larvae was significantly reduced by Se contamination, but was not affected by the presence of perchlorate, Mn, or Cr (VI). All of the contaminants were transferred from plants to D. elongata beetles. Only Cr (VI) was accumulated at greater levels in beetles than in their food. Because T. ramosissima grows in disturbed areas, acquires salts readily, and utilizes groundwater, this plant is likely to accumulate anthropogenic pollutants in contaminated areas. This study is one of the first to investigate the potential of an anthropogenic pollutant to influence a weed biological control system."
755397,Sarto et al. 1990,The micronucleus assay in human exfoliated cells of the nose and mouth: application to occupational exposures to chromic acid and ethylene oxide,"We have applied the micronucleus (MN) assay to exfoliated cells of buccal and nasal cavities to monitor the genotoxic risk in a group of workers exposed to chromic acid and in another group exposed to ethylene oxide (EtO). The first group comprised 16 subjects working in a 'hard' type chrome-plating factory showing increased chromium absorption and chromium-induced rhinopathy. The second group comprised 9 subjects working in a sterilization unit, exposed to EtO concentrations lower than 0.38 ppm as timed weighted average (TWA) for a working shift; 3 of them were involved in a acute exposure too. The frequency of MN in buccal mucosa was within the norm for exposure both to chromium and to EtO. The MN frequency in nasal mucosa was not altered in chromium platers, whereas a significant increase (p less than 0.01) in MN was found in 2 out of 3 subjects involved in the accidental EtO leakage and a non-significant increase in MN was found in the group chronically exposed to EtO.","The micronucleus assay in human exfoliated cells of the nose and mouth: application to occupational exposures to chromic acid and ethylene oxide Abs: We have applied the micronucleus (MN) assay to exfoliated cells of buccal and nasal cavities to monitor the genotoxic risk in a group of workers exposed to chromic acid and in another group exposed to ethylene oxide (EtO). The first group comprised 16 subjects working in a 'hard' type chrome-plating factory showing increased chromium absorption and chromium-induced rhinopathy. The second group comprised 9 subjects working in a sterilization unit, exposed to EtO concentrations lower than 0.38 ppm as timed weighted average (TWA) for a working shift; 3 of them were involved in a acute exposure too. The frequency of MN in buccal mucosa was within the norm for exposure both to chromium and to EtO. The MN frequency in nasal mucosa was not altered in chromium platers, whereas a significant increase (p less than 0.01) in MN was found in 2 out of 3 subjects involved in the accidental EtO leakage and a non-significant increase in MN was found in the group chronically exposed to EtO."
751355,Sánchez-Moreno et al. 2010,Screen-printed sensor for batch and flow injection potentiometric chromium(VI) monitoring,"A disposable screen-printed electrode was designed and evaluated for direct detection of chromium(VI) in batch and flow analysis. The carbon screen-printed electrode was modified with a graphite-epoxy composite. The optimal graphite-epoxy matrix contains 37.5% graphite powder, 12.5% diphenylcarbohydrazide, a selective compound for chromium(VI), and 50% epoxy resin. The principal analytical parameters of the potentiometric response in batch and flow analysis were optimized and calculated. The screen-printed sensor exhibits a response time of 20 +/- 1 s. In flow analysis, the analytical frequency of sampling is 70 injections per hour using 0.1 M NaNO(3) solution at pH 3 as the carrier, a flow rate of 2.5 mL.min(-1), and an injection sample volume of 0.50 mL. The sensor shows potentiometric responses that are very selective for chromium(VI) ions and optimal detection limits in both static mode (2.1 x 10(-7) M) and online analysis (9.4 x 10(-7) M). The disposable potentiometric sensor was employed to determine toxicity levels of chromium(VI) in mineral, tap, and river waters by flow-injection potentiometry and batch potentiometry. Chromium(VI) determination was also carried out with successful results in leachates from municipal solid waste landfills.","Screen-printed sensor for batch and flow injection potentiometric chromium(VI) monitoring Abs: A disposable screen-printed electrode was designed and evaluated for direct detection of chromium(VI) in batch and flow analysis. The carbon screen-printed electrode was modified with a graphite-epoxy composite. The optimal graphite-epoxy matrix contains 37.5% graphite powder, 12.5% diphenylcarbohydrazide, a selective compound for chromium(VI), and 50% epoxy resin. The principal analytical parameters of the potentiometric response in batch and flow analysis were optimized and calculated. The screen-printed sensor exhibits a response time of 20 +/- 1 s. In flow analysis, the analytical frequency of sampling is 70 injections per hour using 0.1 M NaNO(3) solution at pH 3 as the carrier, a flow rate of 2.5 mL.min(-1), and an injection sample volume of 0.50 mL. The sensor shows potentiometric responses that are very selective for chromium(VI) ions and optimal detection limits in both static mode (2.1 x 10(-7) M) and online analysis (9.4 x 10(-7) M). The disposable potentiometric sensor was employed to determine toxicity levels of chromium(VI) in mineral, tap, and river waters by flow-injection potentiometry and batch potentiometry. Chromium(VI) determination was also carried out with successful results in leachates from municipal solid waste landfills."
750698,Hoch et al. 2008,Carbothermal synthesis of carbon-supported nanoscale zero-valent iron particles for the remediation of hexavalent chromium,"Nanoscale, zero-valent iron is a promising reagent for in situ reduction of a variety of subsurface contaminants, but its utility in full-scale remediation projects is limited by material costs. Iron nanoparticles (20-100 nm diameter) supported on carbon (C-Fe0) were synthesized by reacting iron salts, adsorbed or impregnated from aqueous solutions onto 80 m2/g carbon black, at 600-800 degrees C under Ar. Similar products were obtained by heating the reactants under air in a covered alumina crucible. X-ray powder diffraction patterns show that Fe3O4 particles are formed at 300-500 degrees C in the initial stage of the reaction and that these particles are reduced to a mixture of alpha- and gamma-Fe nanoparticles above 600 degrees C. When C-Fe0 was combined with carboxymethylcellulose in a 5:1 weight ratio in water, the resulting material had similar transport properties to previously optimized nanoiron/polyanion suspensions in water-saturated sand columns. At a 10:3 Fe/Cr mole ratio, C-Fe0 reduced a 10 ppm Cr(VI) solution to approximately 1 ppm within three days. The surface area normalized first-order Cr removal rate was 1.2 h(-1) m(-2) under these conditions. These results demonstrate that reactive nanoiron with good transport properties in water-saturated porous media can be made in a scalable process from inexpensive starting materials by carbothermal reduction.","Carbothermal synthesis of carbon-supported nanoscale zero-valent iron particles for the remediation of hexavalent chromium Abs: Nanoscale, zero-valent iron is a promising reagent for in situ reduction of a variety of subsurface contaminants, but its utility in full-scale remediation projects is limited by material costs. Iron nanoparticles (20-100 nm diameter) supported on carbon (C-Fe0) were synthesized by reacting iron salts, adsorbed or impregnated from aqueous solutions onto 80 m2/g carbon black, at 600-800 degrees C under Ar. Similar products were obtained by heating the reactants under air in a covered alumina crucible. X-ray powder diffraction patterns show that Fe3O4 particles are formed at 300-500 degrees C in the initial stage of the reaction and that these particles are reduced to a mixture of alpha- and gamma-Fe nanoparticles above 600 degrees C. When C-Fe0 was combined with carboxymethylcellulose in a 5:1 weight ratio in water, the resulting material had similar transport properties to previously optimized nanoiron/polyanion suspensions in water-saturated sand columns. At a 10:3 Fe/Cr mole ratio, C-Fe0 reduced a 10 ppm Cr(VI) solution to approximately 1 ppm within three days. The surface area normalized first-order Cr removal rate was 1.2 h(-1) m(-2) under these conditions. These results demonstrate that reactive nanoiron with good transport properties in water-saturated porous media can be made in a scalable process from inexpensive starting materials by carbothermal reduction."
750076,Hu et al. 2005,Removal and recovery of Cr(VI) from wastewater by maghemite nanoparticles,"Hexavalent chromium existing in the effluent is a major concern for the metal-processing plant. In this study, a new method combining nanoparticle adsorption and magnetic separation was developed for the removal and recovery of Cr(VI) from wastewater. The nanoscale maghemite was synthesized, characterized, and evaluated as adsorbents of Cr(VI). Various factors influencing the adsorption of Cr(VI), e.g., pH, temperature, initial concentration, and coexisting common ions were studied. Adsorption reached equilibrium within 15 min and was independent of initial Cr concentration. The maximum adsorption occurred at pH 2.5. The adsorption data were analyzed and fitted well by Freundlich isotherm. Cr(VI) adsorption capacity of maghemite nanoparticles was compared favorably with other adsorbents like activated carbon and clay. Competition from common coexisting ions such as Na+, Ca2+, Mg2+, Cu2+, Ni2+, NO3-, and Cl- was ignorable, which illustrated the selective adsorption of Cr(VI) from wastewater. Regeneration studies verified that the maghemite nanoparticles, which underwent six successive adsorption-desorption processes, still retained the original metal removal capacity. In addition, the adsorption mechanisms were investigated using X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), and Raman spectroscopic techniques.","Removal and recovery of Cr(VI) from wastewater by maghemite nanoparticles Abs: Hexavalent chromium existing in the effluent is a major concern for the metal-processing plant. In this study, a new method combining nanoparticle adsorption and magnetic separation was developed for the removal and recovery of Cr(VI) from wastewater. The nanoscale maghemite was synthesized, characterized, and evaluated as adsorbents of Cr(VI). Various factors influencing the adsorption of Cr(VI), e.g., pH, temperature, initial concentration, and coexisting common ions were studied. Adsorption reached equilibrium within 15 min and was independent of initial Cr concentration. The maximum adsorption occurred at pH 2.5. The adsorption data were analyzed and fitted well by Freundlich isotherm. Cr(VI) adsorption capacity of maghemite nanoparticles was compared favorably with other adsorbents like activated carbon and clay. Competition from common coexisting ions such as Na+, Ca2+, Mg2+, Cu2+, Ni2+, NO3-, and Cl- was ignorable, which illustrated the selective adsorption of Cr(VI) from wastewater. Regeneration studies verified that the maghemite nanoparticles, which underwent six successive adsorption-desorption processes, still retained the original metal removal capacity. In addition, the adsorption mechanisms were investigated using X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), and Raman spectroscopic techniques."
749668,Hanaoka et al. 1997,Elevated serum levels of pantropic p53 proteins in chromium workers,"This study investigated the possibility of applying serum pantropic p53 proteins in molecular epidemiologic studies, as a biomarker of environmental carcinogenesis. The serum levels of pantropic p53 proteins were determined in workers with past exposure to hexavalent chromium compounds.<br /><br /> Thirty-one male workers occupationally exposed to hexavalent chromium compounds in the production of chromium compounds for 0 to 23 years served as the exposed group. The referents were 10 volunteers without work-related exposure to chemicals. In the determination of pantropic p53 proteins, commercially available kits for enzyme-linked immunosorbent assay were used which quantitatively detected both mutant and wild-type human p53 proteins.<br /><br /> The serum level of pantropic p53 proteins was in the range of 116.4 to 1122.6 pg/ml for the exposed workers and of 117.4 to 305.8 pg/ml for the referents. Nineteen percent of the exposed workers had a high p53 protein level (6 out of 31) when compared with the referents. All but 1 of the 6 workers had been occupationally exposed to chromium compounds for more than 11 years. Two of the 3 workers with a past history of lung cancer also showed high levels.<br /><br /> Our findings confirm that the application of p53 proteins as a biomarker of environmental carcinogenesis merits further exploration.","Elevated serum levels of pantropic p53 proteins in chromium workers Abs: This study investigated the possibility of applying serum pantropic p53 proteins in molecular epidemiologic studies, as a biomarker of environmental carcinogenesis. The serum levels of pantropic p53 proteins were determined in workers with past exposure to hexavalent chromium compounds.<br /><br /> Thirty-one male workers occupationally exposed to hexavalent chromium compounds in the production of chromium compounds for 0 to 23 years served as the exposed group. The referents were 10 volunteers without work-related exposure to chemicals. In the determination of pantropic p53 proteins, commercially available kits for enzyme-linked immunosorbent assay were used which quantitatively detected both mutant and wild-type human p53 proteins.<br /><br /> The serum level of pantropic p53 proteins was in the range of 116.4 to 1122.6 pg/ml for the exposed workers and of 117.4 to 305.8 pg/ml for the referents. Nineteen percent of the exposed workers had a high p53 protein level (6 out of 31) when compared with the referents. All but 1 of the 6 workers had been occupationally exposed to chromium compounds for more than 11 years. Two of the 3 workers with a past history of lung cancer also showed high levels.<br /><br /> Our findings confirm that the application of p53 proteins as a biomarker of environmental carcinogenesis merits further exploration."
749347,Lantzsch and  Gebel 1997,Genotoxicity of selected metal compounds in the SOS chromotest,"Knowledge concerning the genotoxicity of inorganic metal compounds in the SOS chromotest is limited. Up to now, only Cr(VI), Sn(II) and the platinum antitumor compound cisplatin(II) were shown to be genotoxic in this test system. However, for Cr(VI) and Sn(II), a positive reaction could only be achieved in cytotoxic dose ranges. The aim of the present study was to provide additional data concerning metal salt genotoxicity in the SOS chromotest. Therefore, 14 metal/metalloid salt compounds of platinum, palladium, rhodium, arsenic, antimony and chromium were tested. Four platinum salts, K2PtCl4, cis-Pt(NH3)2Cl2 (cisplatin), trans-Pt(NH3)2Cl2 (transplatin) and PtCl4 as well as two rhodium compounds tested, K2RhCl5 and (NH4)3RhCl6, could be shown to be genotoxic in the chromotest using the tester strain Escherichia coli PQ37. A moderate genotoxicity was shown by the two Cr(VI) compounds K2CrO4 and K2Cr2O7. All palladium compounds and all the other metal salts tested were unable to induce a significant SOS response.","Genotoxicity of selected metal compounds in the SOS chromotest Abs: Knowledge concerning the genotoxicity of inorganic metal compounds in the SOS chromotest is limited. Up to now, only Cr(VI), Sn(II) and the platinum antitumor compound cisplatin(II) were shown to be genotoxic in this test system. However, for Cr(VI) and Sn(II), a positive reaction could only be achieved in cytotoxic dose ranges. The aim of the present study was to provide additional data concerning metal salt genotoxicity in the SOS chromotest. Therefore, 14 metal/metalloid salt compounds of platinum, palladium, rhodium, arsenic, antimony and chromium were tested. Four platinum salts, K2PtCl4, cis-Pt(NH3)2Cl2 (cisplatin), trans-Pt(NH3)2Cl2 (transplatin) and PtCl4 as well as two rhodium compounds tested, K2RhCl5 and (NH4)3RhCl6, could be shown to be genotoxic in the chromotest using the tester strain Escherichia coli PQ37. A moderate genotoxicity was shown by the two Cr(VI) compounds K2CrO4 and K2Cr2O7. All palladium compounds and all the other metal salts tested were unable to induce a significant SOS response."
749289,Stern et al. 1993,Risk assessment of the allergic dermatitis potential of environmental exposure to hexavalent chromium,"Although hexavalent chromium, Cr(VI), is a potent sensitizer and inducer of allergic contact dermatitis and is found in many common materials, no standard or guideline currently exists for protection against these effects in environmental exposure. There appears to be a generalized allergenic potential among the various compounds of Cr(VI). Estimates of the prevalence of Cr sensitivity in the population are uncertain, but range from about 2% of the total population in Finland to as high as 20% in U.S. populations with a dermatitis. Based on the thresholds reported for nine separate patch-test studies and statistical analysis of the aggregate dose-response relationship from 72 separate observations from these studies and on studies of allergic responses to bleaches and detergents, the effective threshold for elicitation of allergic contact dermatitis in sensitized populations is about 10 ppm (mg/L) Cr(VI) (as chromium) in solution. Based on evaluation of the literature on cement dermatitis, the threshold concentration of extractable Cr(VI) in solid material may be as low as 10 ppm (microgram/g). For ingestion of Cr(VI), the lowest observed effect level (LOEL) dose for elicitation is 0.26 microgram/kg. In calculating the threshold concentration of Cr(VI) in soil for elicitation of contact dermatitis, extractability must be taken into account.","Risk assessment of the allergic dermatitis potential of environmental exposure to hexavalent chromium Abs: Although hexavalent chromium, Cr(VI), is a potent sensitizer and inducer of allergic contact dermatitis and is found in many common materials, no standard or guideline currently exists for protection against these effects in environmental exposure. There appears to be a generalized allergenic potential among the various compounds of Cr(VI). Estimates of the prevalence of Cr sensitivity in the population are uncertain, but range from about 2% of the total population in Finland to as high as 20% in U.S. populations with a dermatitis. Based on the thresholds reported for nine separate patch-test studies and statistical analysis of the aggregate dose-response relationship from 72 separate observations from these studies and on studies of allergic responses to bleaches and detergents, the effective threshold for elicitation of allergic contact dermatitis in sensitized populations is about 10 ppm (mg/L) Cr(VI) (as chromium) in solution. Based on evaluation of the literature on cement dermatitis, the threshold concentration of extractable Cr(VI) in solid material may be as low as 10 ppm (microgram/g). For ingestion of Cr(VI), the lowest observed effect level (LOEL) dose for elicitation is 0.26 microgram/kg. In calculating the threshold concentration of Cr(VI) in soil for elicitation of contact dermatitis, extractability must be taken into account."
749288,Bruynzeel et al. 1988,Irritant contact dermatitis and chrome-passivated metal,An outbreak of hand dermatitis is reported amongst employees working on a new assembly line of an electronics factory. 24 out of 41 employees had signs of irritant contact dermatitis. The fingertips and the dorsal parts of the hands were especially affected. Mechanical factors in combination with zinc-chromium compounds from galvanised steel seemed to be responsible for the dermatitis and the dry skin. The use of an emollient solved the problem.,Irritant contact dermatitis and chrome-passivated metal Abs: An outbreak of hand dermatitis is reported amongst employees working on a new assembly line of an electronics factory. 24 out of 41 employees had signs of irritant contact dermatitis. The fingertips and the dorsal parts of the hands were especially affected. Mechanical factors in combination with zinc-chromium compounds from galvanised steel seemed to be responsible for the dermatitis and the dry skin. The use of an emollient solved the problem.
749243,Fregert 1981,Chromium valencies and cement dermatitis,,Chromium valencies and cement dermatitis Abs: 
747284,Elangovan et al. 2009,Hexavalent Chromium Reduction by Free and Immobilized Cell-free Extract of Arthrobacter rhombi-RE,"In the present study, hexavalent chromium (Cr(VI)) reduction potential of chromium reductase associated with the cell-free extracts (CFE) of Arthrobacter rhombi-RE species was evaluated. Arthrobacter rhombi-RE, an efficient Cr(VI) reducing bacterium, was enriched and isolated from a chromium-contaminated site. Chromium reductase activity of Arthrobacter rhombi-RE strain was associated with the cell-free extract and the contribution of extracellular enzymes to Cr(VI) reduction was negligible. NADH enhanced the chromium reductase activity. The enzyme activity was optimal at a pH of 5.5 and a temperature of 30 degrees C. Among the ten electron donors screened, sodium pyruvate was the most effective one followed by NADH and propionic acid. Michaelis-Menten constant, K(m), and maximum reaction rate, V(max), obtained from the Lineweaver-Burk plot were 48 microM and 4.09 nM/mg protein/min, respectively, in presence of NADH as electron donor and 170.5 microM and 4.29 nM/mg protein/min, respectively, in presence of sodium pyruvate as electron donor. Ca(2+) enhanced the enzyme activity while Hg(2+), Cd(2+), Ba(2+), and Zn(2+) inhibited the enzyme activity. Among the various immobilization matrices screened, calcium alginate beads seemed to be the most effective one. Though immobilized enzyme system was able to reduce Cr(VI), the performance was not very encouraging in continuous mode of operation.","Hexavalent Chromium Reduction by Free and Immobilized Cell-free Extract of Arthrobacter rhombi-RE Abs: In the present study, hexavalent chromium (Cr(VI)) reduction potential of chromium reductase associated with the cell-free extracts (CFE) of Arthrobacter rhombi-RE species was evaluated. Arthrobacter rhombi-RE, an efficient Cr(VI) reducing bacterium, was enriched and isolated from a chromium-contaminated site. Chromium reductase activity of Arthrobacter rhombi-RE strain was associated with the cell-free extract and the contribution of extracellular enzymes to Cr(VI) reduction was negligible. NADH enhanced the chromium reductase activity. The enzyme activity was optimal at a pH of 5.5 and a temperature of 30 degrees C. Among the ten electron donors screened, sodium pyruvate was the most effective one followed by NADH and propionic acid. Michaelis-Menten constant, K(m), and maximum reaction rate, V(max), obtained from the Lineweaver-Burk plot were 48 microM and 4.09 nM/mg protein/min, respectively, in presence of NADH as electron donor and 170.5 microM and 4.29 nM/mg protein/min, respectively, in presence of sodium pyruvate as electron donor. Ca(2+) enhanced the enzyme activity while Hg(2+), Cd(2+), Ba(2+), and Zn(2+) inhibited the enzyme activity. Among the various immobilization matrices screened, calcium alginate beads seemed to be the most effective one. Though immobilized enzyme system was able to reduce Cr(VI), the performance was not very encouraging in continuous mode of operation."
744693,Olad et al. 2011,Removal of Toxic Hexavalent Chromium by Polyaniline Modified Clinoptilolite Nanoparticles,"In this work clinoptilolite nanoparticles were modified with conducting polyaniline by the polymerization of anilinium cations in and out side of the clinoptilolite channels and a nanocomposite of polyaniline/clinoptilolite was obtained. Cations (Na+, K+, Mg2+, Ca2+ ...) in the natural clinoptilolite structure were exchanged with anilinium cations by the treatment of clinoptilolite nanoparticles in an acidic solution of aniline monomer. The cation exchange process was confirmed by elemental analysis of nitrogen and carbon atoms of anilinium cations in clinoptilolite dry powder after treatment. The polyaniline/clinoptilolite nanocomposite was obtained by the oxidative polymerization of anilinium cations within the clinoptilolite structure. The polyaniline/clinoptilolite nanocomposite was characterized utilizing FT-IR and X-ray diffraction measurements and was used for the removal of Cr(VI) from aqueous solutions in chromate anion form as an important water pollutant. The effect of a number of parameters such as initial concentration of Cr(VI), amount of nanocomposite and contact time on the removal efficiency of Cr(VI) by polyaniline/clinoptilolite nanocomposite were determined and optimized. It was found that after 5 min of exposure of nanocomposite powder with Cr(VI) solutions in the concentration range of 25 to 100 ppm, more than 98% of chromate anions can be removed and the Cr(VI) removal capacity per one gram of nanocomposite is about 0.3 mmol of Cr(VI).","Removal of Toxic Hexavalent Chromium by Polyaniline Modified Clinoptilolite Nanoparticles Abs: In this work clinoptilolite nanoparticles were modified with conducting polyaniline by the polymerization of anilinium cations in and out side of the clinoptilolite channels and a nanocomposite of polyaniline/clinoptilolite was obtained. Cations (Na+, K+, Mg2+, Ca2+ ...) in the natural clinoptilolite structure were exchanged with anilinium cations by the treatment of clinoptilolite nanoparticles in an acidic solution of aniline monomer. The cation exchange process was confirmed by elemental analysis of nitrogen and carbon atoms of anilinium cations in clinoptilolite dry powder after treatment. The polyaniline/clinoptilolite nanocomposite was obtained by the oxidative polymerization of anilinium cations within the clinoptilolite structure. The polyaniline/clinoptilolite nanocomposite was characterized utilizing FT-IR and X-ray diffraction measurements and was used for the removal of Cr(VI) from aqueous solutions in chromate anion form as an important water pollutant. The effect of a number of parameters such as initial concentration of Cr(VI), amount of nanocomposite and contact time on the removal efficiency of Cr(VI) by polyaniline/clinoptilolite nanocomposite were determined and optimized. It was found that after 5 min of exposure of nanocomposite powder with Cr(VI) solutions in the concentration range of 25 to 100 ppm, more than 98% of chromate anions can be removed and the Cr(VI) removal capacity per one gram of nanocomposite is about 0.3 mmol of Cr(VI)."
738748,Oberholster et al. 2011,Assessment of the effect of nanomaterials on sediment-dwelling invertebrate Chironomus tentans larvae,"Studies were conducted to determine the effects of a panel of seven nanomaterials (NMs), namely: ?-alumina, ?-alumina, precipitated silica; silica fume, calcined silica fume, colloidal antimony pentoxide (Sb(2)O(5)), and superfine amorphous ferric oxide (Fe(2)O(3)), on sediment dwelling invertebrates Chironomus tentans under controlled laboratory conditions. Percentage survival, enzyme activities, growth development, and DNA fragmentation parameters were studied as acute, biochemical, and physiological toxicities of NMs, respectively. Quantitation of catalase and peroxidase enzyme activity demonstrated that toxicant stress of the NMs increased enzyme activity in a concentration dependent fashion across all treatments. The percentage growth length of the test specimens exposed to different NMs was significantly reduced compared to the negative control while only five concentrations were not in the toxic range, namely; Fe(2)O(3) (5 ?g/kg); silica fume (5 ?g/kg, 50 ?g/kg); Sb(2)O(5) (5 ?g/kg) and calcined silica fume (5 ?g/kg). Genotoxic stress assessed by use of DNA laddering showed complementary findings to the other ecotoxicological endpoints tested in this study--the percentage survival and growth length inhibition.","Assessment of the effect of nanomaterials on sediment-dwelling invertebrate Chironomus tentans larvae Abs: Studies were conducted to determine the effects of a panel of seven nanomaterials (NMs), namely: ?-alumina, ?-alumina, precipitated silica; silica fume, calcined silica fume, colloidal antimony pentoxide (Sb(2)O(5)), and superfine amorphous ferric oxide (Fe(2)O(3)), on sediment dwelling invertebrates Chironomus tentans under controlled laboratory conditions. Percentage survival, enzyme activities, growth development, and DNA fragmentation parameters were studied as acute, biochemical, and physiological toxicities of NMs, respectively. Quantitation of catalase and peroxidase enzyme activity demonstrated that toxicant stress of the NMs increased enzyme activity in a concentration dependent fashion across all treatments. The percentage growth length of the test specimens exposed to different NMs was significantly reduced compared to the negative control while only five concentrations were not in the toxic range, namely; Fe(2)O(3) (5 ?g/kg); silica fume (5 ?g/kg, 50 ?g/kg); Sb(2)O(5) (5 ?g/kg) and calcined silica fume (5 ?g/kg). Genotoxic stress assessed by use of DNA laddering showed complementary findings to the other ecotoxicological endpoints tested in this study--the percentage survival and growth length inhibition."
737709,Rosende et al. 2011,Highly integrated flow assembly for automated dynamic extraction and determination of readily bioaccessible chromium(VI) in soils exploiting carbon nanoparticle-based solid-phase extraction,"An automated dynamic leaching test integrated in a portable flow-based setup is herein proposed for reliable determination of readily bioaccessible Cr(VI) under worst-case scenarios in soils containing varying levels of contamination. The manifold is devised to accommodate bi-directional flow extraction followed by processing of extracts via either in-line clean-up/preconcentration using multi-walled carbon nanotubes or automatic dilution at will, along with Cr(VI) derivatization and flow-through spectrophotometric detection. The magnitude of readily mobilizable Cr(VI) pools was ascertained by resorting to water extraction as promulgated by current standard leaching tests. The role of carbon nanomaterials for the uptake of Cr(VI) in soil leachates and the configuration of the packed column integrated in the flow manifold were investigated in detail. The analytical performance of the proposed system for in vitro bioaccessibility tests was evaluated in chromium-enriched soils at environmentally relevant levels and in a standard reference soil material (SRM 2701) with a certified value of total hexavalent chromium. The automated method was proven to afford unbiased assessment of water-soluble Cr(VI) in soils as a result of the minimization of the chromium species transformation. By combination of the kinetic leaching profile and a first-order leaching model, the water-soluble Cr(VI) fraction in soils was determined in merely 6 h against >24 h taken in batchwise steady-state standard methods.","Highly integrated flow assembly for automated dynamic extraction and determination of readily bioaccessible chromium(VI) in soils exploiting carbon nanoparticle-based solid-phase extraction Abs: An automated dynamic leaching test integrated in a portable flow-based setup is herein proposed for reliable determination of readily bioaccessible Cr(VI) under worst-case scenarios in soils containing varying levels of contamination. The manifold is devised to accommodate bi-directional flow extraction followed by processing of extracts via either in-line clean-up/preconcentration using multi-walled carbon nanotubes or automatic dilution at will, along with Cr(VI) derivatization and flow-through spectrophotometric detection. The magnitude of readily mobilizable Cr(VI) pools was ascertained by resorting to water extraction as promulgated by current standard leaching tests. The role of carbon nanomaterials for the uptake of Cr(VI) in soil leachates and the configuration of the packed column integrated in the flow manifold were investigated in detail. The analytical performance of the proposed system for in vitro bioaccessibility tests was evaluated in chromium-enriched soils at environmentally relevant levels and in a standard reference soil material (SRM 2701) with a certified value of total hexavalent chromium. The automated method was proven to afford unbiased assessment of water-soluble Cr(VI) in soils as a result of the minimization of the chromium species transformation. By combination of the kinetic leaching profile and a first-order leaching model, the water-soluble Cr(VI) fraction in soils was determined in merely 6 h against >24 h taken in batchwise steady-state standard methods."
737569,Ashley et al. 2003,Sampling and analysis considerations for the determination of hexavalent chromium in workplace air,"Airborne hexavalent chromium (Cr[VI]) is a known human respiratory carcinogen and allergen. Workers in a variety of industries may be exposed to airborne hexavalent chromium, with exposures frequently occurring via inhalation and/or dermal contact. Analytical methods for the measurement of Cr(VI) compounds in workplace samples, rather than for the determination of total elemental chromium in workplace air, are often desired because exposure limit values for Cr(VI) compounds are much lower than for total Cr. For years, sampling and analytical test methods for airborne Cr(VI) have been investigated so as to provide means for occupational exposure assessment to this highly toxic species. Inter-conversion of trivalent chromium (Cr[III]) and Cr(VI) can sometimes occur during sampling and sample preparation, and efforts to minimize unwanted redox reactions involving these chromium valences have been sought. Because of differences in toxicity, there is also interest in the ability to differentiate between water-soluble and insoluble forms of Cr(VI), and procedures that provide solubility information concerning Cr(VI) compounds have been developed. This paper reviews the state of the art concerning the measurement of airborne Cr(VI) compounds in workplace aerosols and related samples.","Sampling and analysis considerations for the determination of hexavalent chromium in workplace air Abs: Airborne hexavalent chromium (Cr[VI]) is a known human respiratory carcinogen and allergen. Workers in a variety of industries may be exposed to airborne hexavalent chromium, with exposures frequently occurring via inhalation and/or dermal contact. Analytical methods for the measurement of Cr(VI) compounds in workplace samples, rather than for the determination of total elemental chromium in workplace air, are often desired because exposure limit values for Cr(VI) compounds are much lower than for total Cr. For years, sampling and analytical test methods for airborne Cr(VI) have been investigated so as to provide means for occupational exposure assessment to this highly toxic species. Inter-conversion of trivalent chromium (Cr[III]) and Cr(VI) can sometimes occur during sampling and sample preparation, and efforts to minimize unwanted redox reactions involving these chromium valences have been sought. Because of differences in toxicity, there is also interest in the ability to differentiate between water-soluble and insoluble forms of Cr(VI), and procedures that provide solubility information concerning Cr(VI) compounds have been developed. This paper reviews the state of the art concerning the measurement of airborne Cr(VI) compounds in workplace aerosols and related samples."
737543,Loyaux-Lawniczak et al. 2001,Behavior of hexavalent chromium in a polluted groundwater: Redox processes and immobilization in soils,"This work describes the chemical mechanisms governing transport and reduction of hexavalent chromium in soils of a contaminated industrial waste landfill. Groundwater and soil analyses indicate that the main source of chromium is a slag heap essentially consisting of mill tailings. In the groundwater, downstream migration of Cr(IV) is limited thanks to a redox mechanism involving chromate ions and ferrous ions or Fe(II)-bearing minerals. High Fe2+ concentrations in the groundwater are a result of pyrite residues from old activities at the site. Analyses of soil samples reveal that chromium is preferentially located in the soil profile at the fluctuation of the groundwater level. Grain size fractionation of four soil samples was performed, and fraction analyses show that chromium is preferentially accumulated in the clay fraction (<2 microm) and more specifically associated with montmorillonite particles. This work is a demonstration of the reduction of Cr(VI) by Fe(II) studied previously in the laboratory (Buerge, I. J.; Hug, S. J. Environ. Sci. Technol. 1997, 31, 1426-1432; Fendorf, S. E.; Li, G. Environ. Sci. Technol. 1996, 30, 1614-1617; Sedlak, D. L.; Chan, P. G. Geochim. Cosmochim. Acta 1997, 11, 2185-2192) in a field setting. Cr(VI) migration into the groundwater is stopped vertically by the very thick green clay unit and horizontally by the presence of Fe(II) acting as a chemical barrier. The specific site conditions safely prevent any extension of the Cr pollution.","Behavior of hexavalent chromium in a polluted groundwater: Redox processes and immobilization in soils Abs: This work describes the chemical mechanisms governing transport and reduction of hexavalent chromium in soils of a contaminated industrial waste landfill. Groundwater and soil analyses indicate that the main source of chromium is a slag heap essentially consisting of mill tailings. In the groundwater, downstream migration of Cr(IV) is limited thanks to a redox mechanism involving chromate ions and ferrous ions or Fe(II)-bearing minerals. High Fe2+ concentrations in the groundwater are a result of pyrite residues from old activities at the site. Analyses of soil samples reveal that chromium is preferentially located in the soil profile at the fluctuation of the groundwater level. Grain size fractionation of four soil samples was performed, and fraction analyses show that chromium is preferentially accumulated in the clay fraction (<2 microm) and more specifically associated with montmorillonite particles. This work is a demonstration of the reduction of Cr(VI) by Fe(II) studied previously in the laboratory (Buerge, I. J.; Hug, S. J. Environ. Sci. Technol. 1997, 31, 1426-1432; Fendorf, S. E.; Li, G. Environ. Sci. Technol. 1996, 30, 1614-1617; Sedlak, D. L.; Chan, P. G. Geochim. Cosmochim. Acta 1997, 11, 2185-2192) in a field setting. Cr(VI) migration into the groundwater is stopped vertically by the very thick green clay unit and horizontally by the presence of Fe(II) acting as a chemical barrier. The specific site conditions safely prevent any extension of the Cr pollution."
737522,Saraswathy and  Usharani 2007,Monitoring of cellular enzymes in the serum of electroplating workers at Coimbatore,"Chromium compounds are potent toxic and carcinogenic substances. With respect to toxicity, hepatic and renal toxicity have been reported both in workers and in animals exposed to chromium (VI). Chromium (VI) compounds induces DNA damage in vivo and in cultured cells as well as the cytotoxicity evaluated by the leakage of lactate dehydrogenase. The present study reports the cytotoxicity of chrome platers who are employed from 8 to 25 years in electroplating industries at Coimbatore, Tamilnadu. Blood samples were collected and estimated for glutamic oxaloacetic transaminase (GOT), glutamic pyruvic transaminase (GPT), alkaline phosphatase (ALP), lactate dehydrogenase (LDH), creatine phosphokinase (CPK) and total protein in the serum. The study revealed that there is a significant elevation in the level of LDH, ALP, CPK and transaminases and a decrease in total protein in serum. The results of the study suggests that chromium (VI), a hepatotoxic chemical may perhaps damage the plasma membrane resulting in leakage of enzymes in to the serum of chromeplaters.","Monitoring of cellular enzymes in the serum of electroplating workers at Coimbatore Abs: Chromium compounds are potent toxic and carcinogenic substances. With respect to toxicity, hepatic and renal toxicity have been reported both in workers and in animals exposed to chromium (VI). Chromium (VI) compounds induces DNA damage in vivo and in cultured cells as well as the cytotoxicity evaluated by the leakage of lactate dehydrogenase. The present study reports the cytotoxicity of chrome platers who are employed from 8 to 25 years in electroplating industries at Coimbatore, Tamilnadu. Blood samples were collected and estimated for glutamic oxaloacetic transaminase (GOT), glutamic pyruvic transaminase (GPT), alkaline phosphatase (ALP), lactate dehydrogenase (LDH), creatine phosphokinase (CPK) and total protein in the serum. The study revealed that there is a significant elevation in the level of LDH, ALP, CPK and transaminases and a decrease in total protein in serum. The results of the study suggests that chromium (VI), a hepatotoxic chemical may perhaps damage the plasma membrane resulting in leakage of enzymes in to the serum of chromeplaters."
737521,Fernández-Nieto et al. 2006,Occupational asthma due to chromium and nickel salts,"Exposure to chromium and nickel salts is a poorly characterized cause of occupational asthma.<br /><br /> We describe four patients with work-related asthma due to metallic salts. Skin-prick tests to potassium dichromate and nickel sulfate were performed. The patients underwent methacholine inhalation tests and specific inhalation challenges (SIC) with both chromium and nickel salts.<br /><br /> Two patients showed positive skin-prick tests to potassium dichromate and nickel sulfate. All patients had bronchial hyperresponsiveness to methacholine, which increased 24 h after SIC with metallic salts. SIC with potassium dichromate elicited late asthmatic reactions (LAR) in two workers, one subject had an early asthmatic reaction (EAR), and another subject showed a dual asthmatic reaction (DAR). SIC with nickel sulfate induced a DAR in one subject and a late asthmatic reaction in another.<br /><br /> Chromium and nickel salts can give rise to occupational asthma in exposed workers. The underlying mechanism may be IgE-mediated in some cases.","Occupational asthma due to chromium and nickel salts Abs: Exposure to chromium and nickel salts is a poorly characterized cause of occupational asthma.<br /><br /> We describe four patients with work-related asthma due to metallic salts. Skin-prick tests to potassium dichromate and nickel sulfate were performed. The patients underwent methacholine inhalation tests and specific inhalation challenges (SIC) with both chromium and nickel salts.<br /><br /> Two patients showed positive skin-prick tests to potassium dichromate and nickel sulfate. All patients had bronchial hyperresponsiveness to methacholine, which increased 24 h after SIC with metallic salts. SIC with potassium dichromate elicited late asthmatic reactions (LAR) in two workers, one subject had an early asthmatic reaction (EAR), and another subject showed a dual asthmatic reaction (DAR). SIC with nickel sulfate induced a DAR in one subject and a late asthmatic reaction in another.<br /><br /> Chromium and nickel salts can give rise to occupational asthma in exposed workers. The underlying mechanism may be IgE-mediated in some cases."
737520,Lockman 2002,Case report: Allergic contact dermatitis and new-onset asthma. Chromium exposure during leather tanning,,Case report: Allergic contact dermatitis and new-onset asthma. Chromium exposure during leather tanning Abs: 
737519,Uuksulainen et al. 2002,Self-reported occupational health hazards and measured exposures to airborne impurities and noise in shoe repair work,"The authors identified occupational risk factors of shoe repairers and measured their exposures to organic solvents, dust, chromium, degradation products of synthetic shoe materials, and noise. Exposures were measured in 11 shops selected from the workplaces of 82 repairers who responded to a questionnaire about their work environments. The questions dealt with, e.g., chemicals used, work related diseases, perceived hazards in the environment, ventilation, and use of personal protective equipment. Solvent vapor concentration averaged 1.95 (range 0.01-13.2) times the occupational limit (OL) of the mixture during gluing, with higher levels in facilities with no mechanical ventilation. TWA concentrations of organic solvents averaged 0.34 (range 0.01-1.23) times OLs in the breathing-zone samples. Of all shoe repair shops in Finland, 30% had no mechanical ventilation. Concentrations of airborne particles were 0.07-1.01 mg/m3, and those of insoluble and hexavalent chromium 0.10-0.32 and 0.01-0.08 microg/m3, respectively, near roughing, scoring and finishing machines. Several polymer degradation products were present in the air during machining of shoes. Ventilation exchange rates in shops with natural ventilation were less than once/hour. The repairers' average exposure to noise was below 85 dB. They reported many work-related diseases such as rhinitis (prevalence 21%), musculoskeletal disorders (16%), and dermatitis (9%). Measured dust concentrations were low, but the shoe repairers considered dust to be the most common hazard.","Self-reported occupational health hazards and measured exposures to airborne impurities and noise in shoe repair work Abs: The authors identified occupational risk factors of shoe repairers and measured their exposures to organic solvents, dust, chromium, degradation products of synthetic shoe materials, and noise. Exposures were measured in 11 shops selected from the workplaces of 82 repairers who responded to a questionnaire about their work environments. The questions dealt with, e.g., chemicals used, work related diseases, perceived hazards in the environment, ventilation, and use of personal protective equipment. Solvent vapor concentration averaged 1.95 (range 0.01-13.2) times the occupational limit (OL) of the mixture during gluing, with higher levels in facilities with no mechanical ventilation. TWA concentrations of organic solvents averaged 0.34 (range 0.01-1.23) times OLs in the breathing-zone samples. Of all shoe repair shops in Finland, 30% had no mechanical ventilation. Concentrations of airborne particles were 0.07-1.01 mg/m3, and those of insoluble and hexavalent chromium 0.10-0.32 and 0.01-0.08 microg/m3, respectively, near roughing, scoring and finishing machines. Several polymer degradation products were present in the air during machining of shoes. Ventilation exchange rates in shops with natural ventilation were less than once/hour. The repairers' average exposure to noise was below 85 dB. They reported many work-related diseases such as rhinitis (prevalence 21%), musculoskeletal disorders (16%), and dermatitis (9%). Measured dust concentrations were low, but the shoe repairers considered dust to be the most common hazard."
737518,Lee et al. 2002,Nasal septum perforation of welders,"During the periodic physical checkups in 1997-2000, the authors have found eleven cases of nasal septum perforation among 2,869 welders in Ulsan, Korea. They have not suffered from diseases and conditions that could cause septum perforation such as tuberculosis, syphilis, and long-term use of topical corticosteroids. And also they did not have trauma history and surgical experiences on their nasal septum. To investigate the cause of septum perforation we reviewed the past history of pre-employment, the results of annual working environment survey and the material safety data sheets of welding rods and steels with which they have dealt. We also analyzed the concentration of several metals of welding fume and the concentration of blood and urinary chromium. In the result, we assumed that the nasal septum perforation of welders was due to chronic exposure to low-level hexavalent chromium.","Nasal septum perforation of welders Abs: During the periodic physical checkups in 1997-2000, the authors have found eleven cases of nasal septum perforation among 2,869 welders in Ulsan, Korea. They have not suffered from diseases and conditions that could cause septum perforation such as tuberculosis, syphilis, and long-term use of topical corticosteroids. And also they did not have trauma history and surgical experiences on their nasal septum. To investigate the cause of septum perforation we reviewed the past history of pre-employment, the results of annual working environment survey and the material safety data sheets of welding rods and steels with which they have dealt. We also analyzed the concentration of several metals of welding fume and the concentration of blood and urinary chromium. In the result, we assumed that the nasal septum perforation of welders was due to chronic exposure to low-level hexavalent chromium."
737517,Huvinen et al. 2002,Respiratory health effects of long-term exposure to different chromium species in stainless steel production,"The aim of this study was to determine whether occupational exposure to chromite, trivalent chromium (Cr(3+)) or hexavalent chromium (Cr(6+)) causes respiratory diseases, an excess of respiratory symptoms, a decrease in pulmonary function or signs of pneumoconiosis among workers in stainless steel production. Altogether, 203 exposed workers and 81 referents with an average employment of 23 years were investigated for indicators of respiratory health on two occasions, in 1993 and in 1998. Data collection with a self-administered questionnaire, flow volume spirometry, measurement of diffusing capacity, chest radiography and laboratory tests were carried out by a mobile research unit. Exposure to different chromium species and other metals was monitored regularly and studied separately. No adverse respiratory health effects were observed in the group exposed to Cr(6+), either in comparison with the control group in the first cross-sectional study or during the additional 5 year follow-up. Among the Cr (3+) exposed people, the production of phlegm, shortness of breath and breathlessness on exertion were significantly more frequent than in the control group, but the frequency of the symptoms did not increase during the follow-up; no differences were observed in the lung function tests and the radiographic findings did not progress. In the chromite group, the prevalence of breathlessness on exertion was higher than in the control group. However, in the follow-up, the occurrence of symptoms did not differ from 1993 to 1998. In the first study, most parameters of lung function were lower among the smokers in the chromite group than among the smoking controls, but in 1998 the difference was less marked. An average exposure time of 23 years in modern ferrochromium and stainless steel production and low exposure to dusts and fumes containing Cr(6+), Cr(3+), nickel and molybdenum do not lead to respiratory changes detectable by lung function tests or radiography. The workers exposed to Cr(3+) had more respiratory symptoms than those in the control group. The workers in the chromite mine had lower lung function test results than the control group due to earlier exposure to higher dust concentrations.","Respiratory health effects of long-term exposure to different chromium species in stainless steel production Abs: The aim of this study was to determine whether occupational exposure to chromite, trivalent chromium (Cr(3+)) or hexavalent chromium (Cr(6+)) causes respiratory diseases, an excess of respiratory symptoms, a decrease in pulmonary function or signs of pneumoconiosis among workers in stainless steel production. Altogether, 203 exposed workers and 81 referents with an average employment of 23 years were investigated for indicators of respiratory health on two occasions, in 1993 and in 1998. Data collection with a self-administered questionnaire, flow volume spirometry, measurement of diffusing capacity, chest radiography and laboratory tests were carried out by a mobile research unit. Exposure to different chromium species and other metals was monitored regularly and studied separately. No adverse respiratory health effects were observed in the group exposed to Cr(6+), either in comparison with the control group in the first cross-sectional study or during the additional 5 year follow-up. Among the Cr (3+) exposed people, the production of phlegm, shortness of breath and breathlessness on exertion were significantly more frequent than in the control group, but the frequency of the symptoms did not increase during the follow-up; no differences were observed in the lung function tests and the radiographic findings did not progress. In the chromite group, the prevalence of breathlessness on exertion was higher than in the control group. However, in the follow-up, the occurrence of symptoms did not differ from 1993 to 1998. In the first study, most parameters of lung function were lower among the smokers in the chromite group than among the smoking controls, but in 1998 the difference was less marked. An average exposure time of 23 years in modern ferrochromium and stainless steel production and low exposure to dusts and fumes containing Cr(6+), Cr(3+), nickel and molybdenum do not lead to respiratory changes detectable by lung function tests or radiography. The workers exposed to Cr(3+) had more respiratory symptoms than those in the control group. The workers in the chromite mine had lower lung function test results than the control group due to earlier exposure to higher dust concentrations."
737516,Kuo and  Wu 2002,Effects of chromic acid exposure on immunological parameters among electroplating workers,"To investigate the immunological parameters of chromic acid exposure among electroplating workers.<br /><br /> Forty-six subjects were selected from five electroplating plants in central Taiwan. Each subject was interviewed by questionnaire, and urine chromium (urine-Cr) concentration was assessed. Immunological parameters were evaluated by interleukin (IL-2, IL-4, IL-6, IL-8, IL-10, TNF-alpha, IFN-gamma) and levels of lymphocyte subsets (T-cell, B-cell, T4, T8 and T4/T8).<br /><br /> Levels of IL-6 and IL-8 significantly increased in subjects with high urine Cr concentration, but TNF-alpha levels decreased. IL-2, IL-4, IL-10 and IFN-gamma were undetected. Flow cytometry was used to determine levels of lymphocyte subsets: only B-cells percentage had a negative correlation with urine-Cr. Smoking was an important factor that influenced levels of lymphocyte subsets.<br /><br /> Exposure to Cr has a detrimental effect on the immune system, so it is evident that worker exposure to chromic acid in the electroplating workplace must be reduced to a minimum.","Effects of chromic acid exposure on immunological parameters among electroplating workers Abs: To investigate the immunological parameters of chromic acid exposure among electroplating workers.<br /><br /> Forty-six subjects were selected from five electroplating plants in central Taiwan. Each subject was interviewed by questionnaire, and urine chromium (urine-Cr) concentration was assessed. Immunological parameters were evaluated by interleukin (IL-2, IL-4, IL-6, IL-8, IL-10, TNF-alpha, IFN-gamma) and levels of lymphocyte subsets (T-cell, B-cell, T4, T8 and T4/T8).<br /><br /> Levels of IL-6 and IL-8 significantly increased in subjects with high urine Cr concentration, but TNF-alpha levels decreased. IL-2, IL-4, IL-10 and IFN-gamma were undetected. Flow cytometry was used to determine levels of lymphocyte subsets: only B-cells percentage had a negative correlation with urine-Cr. Smoking was an important factor that influenced levels of lymphocyte subsets.<br /><br /> Exposure to Cr has a detrimental effect on the immune system, so it is evident that worker exposure to chromic acid in the electroplating workplace must be reduced to a minimum."
737515,Gibb et al. 2000,Clinical findings of irritation among chromium chemical production workers,"Several reports of workers in chromate production and chromeplating have indicated that exposure to hexavalent chromium is associated with skin and nasal irritation.<br /><br /> A cohort of 2, 357 workers first employed between 1950 and 1974 at a chromate production plant was identified. Clinical findings of irritation were identified by a physician as a result of routine examinations or visits to the medical clinic by members of the cohort. Percentages of the cohort with various clinical findings, the time from hire to occurrence of the first finding, and the mean and median annual hexavalent chromium (measured as CrO(3)) concentration for the job title where the clinical finding first occurred were determined. A proportional hazards model was used to evaluate the relationship between hexavalent chromium exposure and first occurrence of each of the clinical findings.<br /><br /> Nasal irritation and nasal ulceration were the most common clinical findings reported, occurring in more than 60% of the cohort. The average time to first occurrence of these findings was less than 3 months, whereas the time to first occurrence of the other findings ranged from 10 to 22 months. Median exposure to hexavalent chromium at the time of occurrence for most of the findings was about 20 microg/m(3). The proportional hazards model indicated that ulcerated nasal septum, irritated skin, and perforated eardrum were significantly associated with ambient hexavalent chromium exposure; all clinical findings with the exception of conjunctivitis and irritated skin were associated with the calendar year of hire, with the risk being lower as the calendar year of hire became more recent. Annual average ambient hexavalent chromium concentrations generally dropped in the plant over the period of the study.<br /><br /> Workers in the chromate production plant in this study experienced a variety of nasal and skin irritations. Irritated and ulcerated nasal septa, in particular, were quite common clinical findings, occurring in over 60% of the cohort, and they occurred in relatively short periods of time-less than 3 months from date of hire. Annual average concentrations of chromium may not be a good predictor of clinical findings of irritation. Am. J. Ind. Med. 38:127-131, 2000. Published 2000 Wiley-Liss, Inc.","Clinical findings of irritation among chromium chemical production workers Abs: Several reports of workers in chromate production and chromeplating have indicated that exposure to hexavalent chromium is associated with skin and nasal irritation.<br /><br /> A cohort of 2, 357 workers first employed between 1950 and 1974 at a chromate production plant was identified. Clinical findings of irritation were identified by a physician as a result of routine examinations or visits to the medical clinic by members of the cohort. Percentages of the cohort with various clinical findings, the time from hire to occurrence of the first finding, and the mean and median annual hexavalent chromium (measured as CrO(3)) concentration for the job title where the clinical finding first occurred were determined. A proportional hazards model was used to evaluate the relationship between hexavalent chromium exposure and first occurrence of each of the clinical findings.<br /><br /> Nasal irritation and nasal ulceration were the most common clinical findings reported, occurring in more than 60% of the cohort. The average time to first occurrence of these findings was less than 3 months, whereas the time to first occurrence of the other findings ranged from 10 to 22 months. Median exposure to hexavalent chromium at the time of occurrence for most of the findings was about 20 microg/m(3). The proportional hazards model indicated that ulcerated nasal septum, irritated skin, and perforated eardrum were significantly associated with ambient hexavalent chromium exposure; all clinical findings with the exception of conjunctivitis and irritated skin were associated with the calendar year of hire, with the risk being lower as the calendar year of hire became more recent. Annual average ambient hexavalent chromium concentrations generally dropped in the plant over the period of the study.<br /><br /> Workers in the chromate production plant in this study experienced a variety of nasal and skin irritations. Irritated and ulcerated nasal septa, in particular, were quite common clinical findings, occurring in over 60% of the cohort, and they occurred in relatively short periods of time-less than 3 months from date of hire. Annual average concentrations of chromium may not be a good predictor of clinical findings of irritation. Am. J. Ind. Med. 38:127-131, 2000. Published 2000 Wiley-Liss, Inc."
737513,Leroyer et al. 1998,Occupational asthma due to chromium,"We describe a 28-year-old subject employed as a roofer in a construction company since the age of 19, who developed work-related symptoms of a cough, shortness of breath, wheezing, rhinitis and headaches. A description of a usual day at work suggested that the symptoms worsened while he was sawing corrugated fiber cement. Baseline spirometry was normal, and there was a mild bronchial hyperresponsiveness to carbachol. A skin patch test to chromium was negative. A specific inhalation challenge showed a boderline fall in forced expiratory volume in 1 s (FEV1) after exposure to fiber cement dust. Exposure to nebulization of potassium dichromate (K2Cr2O7), at 0.1 mg.ml-1 for 30 min, was followed by an immediate fall by 20% FEV1. Simultaneously, a significant increase in bronchial hyperresponsiveness was demonstrated.","Occupational asthma due to chromium Abs: We describe a 28-year-old subject employed as a roofer in a construction company since the age of 19, who developed work-related symptoms of a cough, shortness of breath, wheezing, rhinitis and headaches. A description of a usual day at work suggested that the symptoms worsened while he was sawing corrugated fiber cement. Baseline spirometry was normal, and there was a mild bronchial hyperresponsiveness to carbachol. A skin patch test to chromium was negative. A specific inhalation challenge showed a boderline fall in forced expiratory volume in 1 s (FEV1) after exposure to fiber cement dust. Exposure to nebulization of potassium dichromate (K2Cr2O7), at 0.1 mg.ml-1 for 30 min, was followed by an immediate fall by 20% FEV1. Simultaneously, a significant increase in bronchial hyperresponsiveness was demonstrated."
737512,De Raeve et al. 1998,Dermal and respiratory sensitization to chromate in a cement floorer,"To report a well-documented case of both allergic contact dermatitis and occupational asthma due to chromate exposure in a 48-year-old floorer.<br /><br /> A 48-year-old floorer, occupationally exposed to cement and with a documented chromate contact dermatitis, reported dyspnea and wheezing after work. These conditions were demonstrated by self-measured sequential peak expiratory flows. A first bronchial provocation (BPT) with potassium dichromate (K2Cr2O7) (0.3% nebulized for a total of 60 minutes) led to pronounced and sustained decreases in forced expiratory volume in 1 second (FEV1) and forced vital capacity, accompanied by pruritus, a decrease in arterial PO2, a slight rise in temperature, and peripheral blood leukocytosis. (This concentration of K2Cr2O7 is not recommended for BPT). Bronchoalveolar lavage performed 2 days later showed 18% eosinophils. Tow years later, a BPT with a lower dose of K2Cr2O7 (0.01% for the total of 31 min) led to an ""earl late"" reaction (FEV1 dropped by 195 compared with the initial FEV1 value), accompanied by pruritus. A BPT with dry cement, containing 12 ppm hexavalent chromium, was borderline (FEV1 dropped by 13%), and a similar result (FEV1 dropped by 14%) was obtained after smoking five cigarettes, laced with 10 mg of cement per cigarette.<br /><br /> This report illustrates that a subject, with allergic contact dermatitis to chromates, may develop a respiratory allergic reaction to an airborne source of this metal. The main novelty of our report is that the smoking of cigarettes contaminated with cement may have been significant factor in the causation or elicitation of these reactions.","Dermal and respiratory sensitization to chromate in a cement floorer Abs: To report a well-documented case of both allergic contact dermatitis and occupational asthma due to chromate exposure in a 48-year-old floorer.<br /><br /> A 48-year-old floorer, occupationally exposed to cement and with a documented chromate contact dermatitis, reported dyspnea and wheezing after work. These conditions were demonstrated by self-measured sequential peak expiratory flows. A first bronchial provocation (BPT) with potassium dichromate (K2Cr2O7) (0.3% nebulized for a total of 60 minutes) led to pronounced and sustained decreases in forced expiratory volume in 1 second (FEV1) and forced vital capacity, accompanied by pruritus, a decrease in arterial PO2, a slight rise in temperature, and peripheral blood leukocytosis. (This concentration of K2Cr2O7 is not recommended for BPT). Bronchoalveolar lavage performed 2 days later showed 18% eosinophils. Tow years later, a BPT with a lower dose of K2Cr2O7 (0.01% for the total of 31 min) led to an ""earl late"" reaction (FEV1 dropped by 195 compared with the initial FEV1 value), accompanied by pruritus. A BPT with dry cement, containing 12 ppm hexavalent chromium, was borderline (FEV1 dropped by 13%), and a similar result (FEV1 dropped by 14%) was obtained after smoking five cigarettes, laced with 10 mg of cement per cigarette.<br /><br /> This report illustrates that a subject, with allergic contact dermatitis to chromates, may develop a respiratory allergic reaction to an airborne source of this metal. The main novelty of our report is that the smoking of cigarettes contaminated with cement may have been significant factor in the causation or elicitation of these reactions."
737511,Williams 1998,Nasal septal ulceration and perforation in jiggers,"The paper describes two cases of occupational ill-health in individuals working as jiggers in the chromium electroplating industry. Much has been written about the effects of chromic acid on the platers who may work directly over the plating baths, but a literature search failed to identify any reports of ill-health in those who work alongside platers preparing the items to be placed into the baths. One case of nasal ulceration and one of nasal septal perforation are described. Reference is made to the role of the 'responsible person' in health surveillance for such workers to allow early identification of occupationally acquired ill-health and prevention of further cases.","Nasal septal ulceration and perforation in jiggers Abs: The paper describes two cases of occupational ill-health in individuals working as jiggers in the chromium electroplating industry. Much has been written about the effects of chromic acid on the platers who may work directly over the plating baths, but a literature search failed to identify any reports of ill-health in those who work alongside platers preparing the items to be placed into the baths. One case of nasal ulceration and one of nasal septal perforation are described. Reference is made to the role of the 'responsible person' in health surveillance for such workers to allow early identification of occupationally acquired ill-health and prevention of further cases."
737510,Fagliano et al. 1997,Community exposure and medical screening near chromium waste sites in New Jersey,"Chromium waste slag containing potentially hazardous levels of hexavalent chromium was used as fill material at more than 160 residential, industrial, and recreational sites. Persons living or working in the vicinity of the sites may have been exposed through inhalation, ingestion, or skin contact with contaminated soils and dusts. In 1992-1993, the New Jersey Department of Health and Senior Services (NJDHSS) and the Environmental and Occupational Health Sciences Institute (EOHSI) conducted a screening project to assess exposure to chromium and to provide medical evaluations to people living in 14 residential areas or working in 78 workplaces near chromium waste sites. The screening included a physical examination for irritant or allergic effects and a urine chromium test for recent exposure. Participants were referred for follow-up medical evaluation if specific criteria were met. Of 800 residents and 938 workers receiving the screening physical examination, 32 adults were referred for follow-up evaluation. Of 806 residents and 934 workers submitting a urine specimen for chromium analysis, 158 adults and children had levels exceeding specified criteria and were referred for follow-up evaluation. The proportion of persons referred on the basis of the urine chromium test varied among screened groups. Multiple linear regression models showed that average urine chromium differences between residents and a comparison group, adjusting for potential confounders, were highest in children under 6 years of age. Most of the persons undergoing the follow-up medical examinations revealed no apparent clinical effects attributable to chromium exposure. The screening results indicated the need for expanded environmental evaluation in specific residential areas and workplaces.","Community exposure and medical screening near chromium waste sites in New Jersey Abs: Chromium waste slag containing potentially hazardous levels of hexavalent chromium was used as fill material at more than 160 residential, industrial, and recreational sites. Persons living or working in the vicinity of the sites may have been exposed through inhalation, ingestion, or skin contact with contaminated soils and dusts. In 1992-1993, the New Jersey Department of Health and Senior Services (NJDHSS) and the Environmental and Occupational Health Sciences Institute (EOHSI) conducted a screening project to assess exposure to chromium and to provide medical evaluations to people living in 14 residential areas or working in 78 workplaces near chromium waste sites. The screening included a physical examination for irritant or allergic effects and a urine chromium test for recent exposure. Participants were referred for follow-up medical evaluation if specific criteria were met. Of 800 residents and 938 workers receiving the screening physical examination, 32 adults were referred for follow-up evaluation. Of 806 residents and 934 workers submitting a urine specimen for chromium analysis, 158 adults and children had levels exceeding specified criteria and were referred for follow-up evaluation. The proportion of persons referred on the basis of the urine chromium test varied among screened groups. Multiple linear regression models showed that average urine chromium differences between residents and a comparison group, adjusting for potential confounders, were highest in children under 6 years of age. Most of the persons undergoing the follow-up medical examinations revealed no apparent clinical effects attributable to chromium exposure. The screening results indicated the need for expanded environmental evaluation in specific residential areas and workplaces."
737506,Huvinen et al. 1996,Respiratory health of workers exposed to low levels of chromium in stainless steel production,"To determine whether occupational exposure to chromite, trivalent chromium, or hexavalent chromium causes respiratory diseases, an excess of respiratory symptoms, a decrease in pulmonary function, or signs of pneumoconiosis among workers in an integrated chain of stainless steel production.<br /><br /> This cross sectional study was carried out in 1993 and the inclusion criterion was a minimum of eight years of employment in the same production department. A self administered questionnaire was collected, and spirometry, measurement of diffusing capacity, chest radiography, and laboratory tests were carried out by a mobile research unit.<br /><br /> There were 221 workers in the exposure groups and 95 in the control group. The average duration of employment was 18 years. No significant differences in the odds ratios (ORs) of the symptoms were found between the exposure and the control groups. In a logistic regression analysis age and smoking significantly explained the occurrence of most of the respiratory symptoms. The smokers in the chromite group had significantly lower forced vital capacity (FVC), forced expiratory volume in one second (FEV1), and diffusing capacity than the corresponding values of the control group. The analysis of variance between study groups, smoking, and exposure time, without modelling for interactions, showed that the chromite group had lower values for FVC, FEV1, and diffusing capacity than the other groups. The occurrence of small opacities was more frequent on the chest radiographs of the workers in the chromite group.<br /><br /> An average exposure time of 18 years in ferrochromium and stainless steel production and exposure to dusts containing low concentrations of hexavalent or trivalent chromium do not lead to any respiratory changes detectable by lung function tests or radiography nor to any increase in symptoms of respiratory diseases. The lung function values were lower and the occurrence of radiological findings was more frequent among the workers from the chromite mine than among the controls. The difference was partly caused by differences in age and smoking habits, but evidently also partly by higher exposures more than two decades ago or by the fibrous components of the dust.","Respiratory health of workers exposed to low levels of chromium in stainless steel production Abs: To determine whether occupational exposure to chromite, trivalent chromium, or hexavalent chromium causes respiratory diseases, an excess of respiratory symptoms, a decrease in pulmonary function, or signs of pneumoconiosis among workers in an integrated chain of stainless steel production.<br /><br /> This cross sectional study was carried out in 1993 and the inclusion criterion was a minimum of eight years of employment in the same production department. A self administered questionnaire was collected, and spirometry, measurement of diffusing capacity, chest radiography, and laboratory tests were carried out by a mobile research unit.<br /><br /> There were 221 workers in the exposure groups and 95 in the control group. The average duration of employment was 18 years. No significant differences in the odds ratios (ORs) of the symptoms were found between the exposure and the control groups. In a logistic regression analysis age and smoking significantly explained the occurrence of most of the respiratory symptoms. The smokers in the chromite group had significantly lower forced vital capacity (FVC), forced expiratory volume in one second (FEV1), and diffusing capacity than the corresponding values of the control group. The analysis of variance between study groups, smoking, and exposure time, without modelling for interactions, showed that the chromite group had lower values for FVC, FEV1, and diffusing capacity than the other groups. The occurrence of small opacities was more frequent on the chest radiographs of the workers in the chromite group.<br /><br /> An average exposure time of 18 years in ferrochromium and stainless steel production and exposure to dusts containing low concentrations of hexavalent or trivalent chromium do not lead to any respiratory changes detectable by lung function tests or radiography nor to any increase in symptoms of respiratory diseases. The lung function values were lower and the occurrence of radiological findings was more frequent among the workers from the chromite mine than among the controls. The difference was partly caused by differences in age and smoking habits, but evidently also partly by higher exposures more than two decades ago or by the fibrous components of the dust."
736124,van Loveren et al. 2008,Skin sensitization in chemical risk assessment: report of a WHO/IPCS international workshop focusing on dose-response assessment,"An international workshop was held in 2006 to evaluate experimental techniques for hazard identification and hazard characterization of sensitizing agents in terms of their ability to produce data, including dose-response information, to inform risk assessment. Human testing to identify skin sensitizers is discouraged for ethical reasons. Animal-free alternatives, such as quantitative structure-activity relationships and in vitro testing approaches, have not been sufficiently developed for such application. Guinea pig tests do not generally include dose-response assessment and are therefore not designed for the assessment of potency, defined as the relative ability of a chemical to induce sensitization in a previously naive individual. In contrast, the mouse local lymph node assay does include dose-response assessment and is appropriate for this purpose. Epidemiological evidence can be used only under certain circumstances for the evaluation of the sensitizing potency of chemicals, as it reflects degree of exposure as well as intrinsic potency. Nevertheless, human diagnostic patch test data and quantitative elicitation data have provided very important information in reducing allergic contact dermatitis risk and sensitization in the general population. It is therefore recommended that clinical data, particularly dose-response data derived from sensitized patients, be included in risk assessment.","Skin sensitization in chemical risk assessment: report of a WHO/IPCS international workshop focusing on dose-response assessment Abs: An international workshop was held in 2006 to evaluate experimental techniques for hazard identification and hazard characterization of sensitizing agents in terms of their ability to produce data, including dose-response information, to inform risk assessment. Human testing to identify skin sensitizers is discouraged for ethical reasons. Animal-free alternatives, such as quantitative structure-activity relationships and in vitro testing approaches, have not been sufficiently developed for such application. Guinea pig tests do not generally include dose-response assessment and are therefore not designed for the assessment of potency, defined as the relative ability of a chemical to induce sensitization in a previously naive individual. In contrast, the mouse local lymph node assay does include dose-response assessment and is appropriate for this purpose. Epidemiological evidence can be used only under certain circumstances for the evaluation of the sensitizing potency of chemicals, as it reflects degree of exposure as well as intrinsic potency. Nevertheless, human diagnostic patch test data and quantitative elicitation data have provided very important information in reducing allergic contact dermatitis risk and sensitization in the general population. It is therefore recommended that clinical data, particularly dose-response data derived from sensitized patients, be included in risk assessment."
736123,Duarte et al. 2010,Frequency of occupational contact dermatitis in an ambulatory of dermatologic allergy,"Occupational contact dermatitis (OCD) corresponds to 80% of the cases of skin diseases related to work.<br /><br /> To determine: the frequency of OCD in an ambulatory of allergy not specific for occupational dermatosis; the profile of these patients according to age, gender, color, profession, atopic history, duration and localization of the dermatosis; the diagnosed types of contact dermatitis; the main allergens and to compare the frequency of the main antigens with the results obtained from patients examined in the same period of time, without DCO.<br /><br /> During the three-year period from 2003 to 2006, 630 patients were examined and submitted to a battery of standardized contact patch tests and those who were diagnosed with OCD were selected.<br /><br /> Sixty-nine out of the 630 patients were diagnosed with OCD. The average age was 44.5 years. Forty-eight patients (70%of the cases) presented the disease on the hands. The most prevalent activities of patients suffering from the disease were household tasks (39%) and building construction (33%). The allergic contact dermatitis (ACD) occurred in 48 cases which represent 70% of the total number of cases and irritant contact dermatitis in 21 cases corresponding to 30% of the total number of cases. The main allergens were potassium dichromate 28 (41%), nickel sulfate 16 (23%) and carba-mix 16 (23%).<br /><br /> OCD was present in 10.9% of the patients. Concerning age the group in which the disease was more commonly found corresponded to the most productive group of the population. ACD corresponded to 48 cases, probably influenced by the long period of evolution of the dermatosis. Metal and rubber chemicals were the commonest allergens.","Frequency of occupational contact dermatitis in an ambulatory of dermatologic allergy Abs: Occupational contact dermatitis (OCD) corresponds to 80% of the cases of skin diseases related to work.<br /><br /> To determine: the frequency of OCD in an ambulatory of allergy not specific for occupational dermatosis; the profile of these patients according to age, gender, color, profession, atopic history, duration and localization of the dermatosis; the diagnosed types of contact dermatitis; the main allergens and to compare the frequency of the main antigens with the results obtained from patients examined in the same period of time, without DCO.<br /><br /> During the three-year period from 2003 to 2006, 630 patients were examined and submitted to a battery of standardized contact patch tests and those who were diagnosed with OCD were selected.<br /><br /> Sixty-nine out of the 630 patients were diagnosed with OCD. The average age was 44.5 years. Forty-eight patients (70%of the cases) presented the disease on the hands. The most prevalent activities of patients suffering from the disease were household tasks (39%) and building construction (33%). The allergic contact dermatitis (ACD) occurred in 48 cases which represent 70% of the total number of cases and irritant contact dermatitis in 21 cases corresponding to 30% of the total number of cases. The main allergens were potassium dichromate 28 (41%), nickel sulfate 16 (23%) and carba-mix 16 (23%).<br /><br /> OCD was present in 10.9% of the patients. Concerning age the group in which the disease was more commonly found corresponded to the most productive group of the population. ACD corresponded to 48 cases, probably influenced by the long period of evolution of the dermatosis. Metal and rubber chemicals were the commonest allergens."
736122,Geier et al. 2011,Occupational contact allergy in the building trade in Germany: influence of preventive measures and changing exposure,"Since 1993, assiduous efforts have been made in Germany to lower the incidence of allergic cement dermatitis by reducing the content of hexavalent chromium (Cr VI). Usage of epoxy resin systems has considerably increased in the building trade in the same period. We analysed data of the Information Network of Departments of Dermatology (IVDK) to evaluate the influence of these changing occupational exposures on frequencies of sensitization.<br /><br /> IVDK data of 1,153 men working in the building trade (bricklayers, tile setters etc.) presenting with occupational skin disease in the years 1994-2008 were analysed, taking into consideration not only the year of patch testing, but also beginning and duration of work in the building trade.<br /><br /> While contact sensitization to chromate decreased from 43.1 to 29.0%, sensitization to epoxy resin increased from 8.4 to 12.4%. Logistic regression analysis revealed that, compared to those who had already worked before 1994, patients having started to work in building trade after 1999 had a significantly decreased risk of chromate sensitization (odds ratio 0.42) and a significantly increased risk of sensitization to epoxy resin (odds ratio 2.79). Additionally, risk of thiuram sensitization increased with the duration of employment.<br /><br /> Our data confirm that reducing Cr VI content of cement is useful in preventing allergic cement eczema, as previously found in Scandinavia. In contrast, the increasing prevalence of contact sensitization to epoxy resin components in the building trade is alarming. Preventive measures, which have already been implemented, have to be enforced.","Occupational contact allergy in the building trade in Germany: influence of preventive measures and changing exposure Abs: Since 1993, assiduous efforts have been made in Germany to lower the incidence of allergic cement dermatitis by reducing the content of hexavalent chromium (Cr VI). Usage of epoxy resin systems has considerably increased in the building trade in the same period. We analysed data of the Information Network of Departments of Dermatology (IVDK) to evaluate the influence of these changing occupational exposures on frequencies of sensitization.<br /><br /> IVDK data of 1,153 men working in the building trade (bricklayers, tile setters etc.) presenting with occupational skin disease in the years 1994-2008 were analysed, taking into consideration not only the year of patch testing, but also beginning and duration of work in the building trade.<br /><br /> While contact sensitization to chromate decreased from 43.1 to 29.0%, sensitization to epoxy resin increased from 8.4 to 12.4%. Logistic regression analysis revealed that, compared to those who had already worked before 1994, patients having started to work in building trade after 1999 had a significantly decreased risk of chromate sensitization (odds ratio 0.42) and a significantly increased risk of sensitization to epoxy resin (odds ratio 2.79). Additionally, risk of thiuram sensitization increased with the duration of employment.<br /><br /> Our data confirm that reducing Cr VI content of cement is useful in preventing allergic cement eczema, as previously found in Scandinavia. In contrast, the increasing prevalence of contact sensitization to epoxy resin components in the building trade is alarming. Preventive measures, which have already been implemented, have to be enforced."
736121,Milingou et al. 2010,Patch tests in children: A review of 13 years of experience in comparison with previous data,"The true prevalence of allergic contact dermatitis (ACD) in children remains unknown. Our aim was to compare the results of patch tests in children with suspected ACD between two different periods of time and identify possible changes in emerging allergens. We compared contact allergens, gender, age distribution, and personal history of atopic dermatitis (AD), in correlation with the positivity of patch tests, between two equal periods of time (232 children tested during 1980-1993, period A, and 255 children during 1994-2007, period B) in the same region and in the same institution. Patch test positivity was 47.8% in period A, and 60% in period B (p = 0.083). The most common allergens in period A were: nickel sulfate (16.3%), cobalt chloride (8.6%), fragrance mix (7.3%), potassium dichromate (4.3%), and thimerosal only (1.7%). In period B, the allergen distribution was as follows: nickel sulfate (21.56%), thimerosal (18.03%), cobalt chloride (12.9%), potassium dichromate (9.4%), and fragrance mix (4.7%). Girls were more likely to have a positive patch test compared with boys, with reactions in 53% of girls and 39% of boys in period A (p = 0.003), and 61% of girls and 58% of boys in period B (p = 0.691). Twenty-nine per cent of patients with positive results had a personal history of AD in period A and 44% in period B (p = 0.015). Differences in the positivity of allergens between different time periods reflect changes in habits, of allergens exposure or preventive measures.","Patch tests in children: A review of 13 years of experience in comparison with previous data Abs: The true prevalence of allergic contact dermatitis (ACD) in children remains unknown. Our aim was to compare the results of patch tests in children with suspected ACD between two different periods of time and identify possible changes in emerging allergens. We compared contact allergens, gender, age distribution, and personal history of atopic dermatitis (AD), in correlation with the positivity of patch tests, between two equal periods of time (232 children tested during 1980-1993, period A, and 255 children during 1994-2007, period B) in the same region and in the same institution. Patch test positivity was 47.8% in period A, and 60% in period B (p = 0.083). The most common allergens in period A were: nickel sulfate (16.3%), cobalt chloride (8.6%), fragrance mix (7.3%), potassium dichromate (4.3%), and thimerosal only (1.7%). In period B, the allergen distribution was as follows: nickel sulfate (21.56%), thimerosal (18.03%), cobalt chloride (12.9%), potassium dichromate (9.4%), and fragrance mix (4.7%). Girls were more likely to have a positive patch test compared with boys, with reactions in 53% of girls and 39% of boys in period A (p = 0.003), and 61% of girls and 58% of boys in period B (p = 0.691). Twenty-nine per cent of patients with positive results had a personal history of AD in period A and 44% in period B (p = 0.015). Differences in the positivity of allergens between different time periods reflect changes in habits, of allergens exposure or preventive measures."
736120,Dickel et al. 2010,Increased sensitivity of patch testing by standardized tape stripping beforehand: a multicentre diagnostic accuracy study,"As a modification of patch testing, the strip patch test was established to obtain more sensitive and reliable test results. Comparative data on diagnostic accuracy for both tests are missing.<br /><br /> To compare the diagnostic accuracy of strip patch tests and patch tests in detecting sensitizations in patients with suspected allergic contact dermatitis by using patient history as the reference standard.<br /><br /> In a multicentre, prospective, investigator-blinded study 790 patients were enrolled. The defined reference standard was established prior to patch testing. Patch tests were performed with nickel sulfate, potassium dichromate, and lanolin alcohol. Duplicate tests were simultaneously performed on both sides of the back, of which one randomly chosen side was tape stripped beforehand, according to a standardized procedure. Primary outcome was the difference in sensitivity between strip patch test and patch test.<br /><br /> Seven hundred and eighty-seven patients were included in the analysis. Strip patch tests detected considerably more sensitization to nickel sulfate and potassium dichromate than patch tests: differences of sensitivities were 16.4% (95% CI, 8.7-24.1%) for nickel sulfate and 25.0% (95% CI, 8.9-41.0%) for potassium dichromate, both favouring the strip patch test.<br /><br /> The standardized strip patch test proved to be accurate and clinically safe and is promising to improve diagnosis of allergic contact dermatitis beyond the patch test.","Increased sensitivity of patch testing by standardized tape stripping beforehand: a multicentre diagnostic accuracy study Abs: As a modification of patch testing, the strip patch test was established to obtain more sensitive and reliable test results. Comparative data on diagnostic accuracy for both tests are missing.<br /><br /> To compare the diagnostic accuracy of strip patch tests and patch tests in detecting sensitizations in patients with suspected allergic contact dermatitis by using patient history as the reference standard.<br /><br /> In a multicentre, prospective, investigator-blinded study 790 patients were enrolled. The defined reference standard was established prior to patch testing. Patch tests were performed with nickel sulfate, potassium dichromate, and lanolin alcohol. Duplicate tests were simultaneously performed on both sides of the back, of which one randomly chosen side was tape stripped beforehand, according to a standardized procedure. Primary outcome was the difference in sensitivity between strip patch test and patch test.<br /><br /> Seven hundred and eighty-seven patients were included in the analysis. Strip patch tests detected considerably more sensitization to nickel sulfate and potassium dichromate than patch tests: differences of sensitivities were 16.4% (95% CI, 8.7-24.1%) for nickel sulfate and 25.0% (95% CI, 8.9-41.0%) for potassium dichromate, both favouring the strip patch test.<br /><br /> The standardized strip patch test proved to be accurate and clinically safe and is promising to improve diagnosis of allergic contact dermatitis beyond the patch test."
736119,Ertam et al. 2008,"Patch-test results of an academic department in Izmir, Turkey","With the development of industry, the numbers of allergens are increasing, and the frequency of these allergens show variations from country to country. The aim of this retrospective study was to determine the distribution of patch-test results by age, gender, and occupation in our region.<br /><br /> In a retrospective study, the patch-test results of 3,017 patients were evaluated. The results were statistically examined by frequency of age, gender, and occupation. Chi-square and Fisher exact tests were used for statistical evaluation.<br /><br /> Of 3,017 patients, 1,975 (65.5%) were female and 1,042 (34.5%) were male. Their ages ranged from 5 to 85 years (mean, 40.38 +/-14.69 years). In 944 (31.3%) patients, at least one positive reaction to an allergen was observed. The allergens that most commonly caused positive reactions were nickel sulfate (12.2%), cobalt chloride (7.1%), potassium dichromate (5.6%), and balsam of Peru (2.8%). Balsam of Peru and nickel were the most common allergens in female patients older than 45 years and in female patients younger than 35 years, respectively.<br /><br /> Nickel sulfate and cobalt chloride were found to be the most common allergens. The most frequently seen allergens were nickel sulfate (in females) and fragrance (in males).","Patch-test results of an academic department in Izmir, Turkey Abs: With the development of industry, the numbers of allergens are increasing, and the frequency of these allergens show variations from country to country. The aim of this retrospective study was to determine the distribution of patch-test results by age, gender, and occupation in our region.<br /><br /> In a retrospective study, the patch-test results of 3,017 patients were evaluated. The results were statistically examined by frequency of age, gender, and occupation. Chi-square and Fisher exact tests were used for statistical evaluation.<br /><br /> Of 3,017 patients, 1,975 (65.5%) were female and 1,042 (34.5%) were male. Their ages ranged from 5 to 85 years (mean, 40.38 +/-14.69 years). In 944 (31.3%) patients, at least one positive reaction to an allergen was observed. The allergens that most commonly caused positive reactions were nickel sulfate (12.2%), cobalt chloride (7.1%), potassium dichromate (5.6%), and balsam of Peru (2.8%). Balsam of Peru and nickel were the most common allergens in female patients older than 45 years and in female patients younger than 35 years, respectively.<br /><br /> Nickel sulfate and cobalt chloride were found to be the most common allergens. The most frequently seen allergens were nickel sulfate (in females) and fragrance (in males)."
736118,Balato et al. 2008,"Contact sensitization of older patients in an academic department in Naples, Italy","Contact allergy develops in predisposed individuals as a consequence of environmental exposure to allergens. Exposure patterns change over time because of many factors (sex, age, occupation, fashion trends, official regulations), and the delayed hypersensitivity response depends significantly on the age of the subject.<br /><br /> The aim of the present study was to investigate the prevalence of contact sensitization in older patients (older than 65 years) referred to our allergologic clinic.<br /><br /> All patients were patch-tested with the standard series of the Societè Italiana di Dermatologia Allergologica, Professionale e Ambientale, and 32 patients were also tested with additional series.<br /><br /> Of 117 examined subjects, 48 (41%) developed at least one positive reaction whereas 22 of 117 (19%) showed more than one sensitization. Allergic contact dermatitis was detected in 13% of our sample. The five most frequent allergens were nickel sulfate (13.7%), potassium dichromate (11.1%), cobalt chloride (7.7%), para-phenylenediamine (5.2%), and balsam of Peru (4.3%).<br /><br /> These findings suggest an age-dependent decline of overall positive patch-test reactions but a higher sensitization rate to some allergens.","Contact sensitization of older patients in an academic department in Naples, Italy Abs: Contact allergy develops in predisposed individuals as a consequence of environmental exposure to allergens. Exposure patterns change over time because of many factors (sex, age, occupation, fashion trends, official regulations), and the delayed hypersensitivity response depends significantly on the age of the subject.<br /><br /> The aim of the present study was to investigate the prevalence of contact sensitization in older patients (older than 65 years) referred to our allergologic clinic.<br /><br /> All patients were patch-tested with the standard series of the Societè Italiana di Dermatologia Allergologica, Professionale e Ambientale, and 32 patients were also tested with additional series.<br /><br /> Of 117 examined subjects, 48 (41%) developed at least one positive reaction whereas 22 of 117 (19%) showed more than one sensitization. Allergic contact dermatitis was detected in 13% of our sample. The five most frequent allergens were nickel sulfate (13.7%), potassium dichromate (11.1%), cobalt chloride (7.7%), para-phenylenediamine (5.2%), and balsam of Peru (4.3%).<br /><br /> These findings suggest an age-dependent decline of overall positive patch-test reactions but a higher sensitization rate to some allergens."
736115,Bock et al. 2003,Occupational skin disease in the construction industry,"Construction workers have a substantial risk of developing irritant and/or allergic contact dermatitis. Unfortunately, however, there is little population-based epidemiological data relating to occupational skin diseases (OSD) in the European construction industry that allow assessment of preventive measures.<br /><br /> In this investigation, the yearly incidence rates and causes of OSD in the construction industry were analysed on the basis of our register in Northern Bavaria.<br /><br /> From 1990 until 1999, all incidences of OSD in the construction industry were recorded prospectively. This enables the calculation of incidence rates of OSD in relation to the employed population in Northern Bavaria as recorded by the German Federal Employment Office.<br /><br /> In the construction industry, a total of 335 OSD were registered. These comprise 9.0% of all OSD in the register. We classified them into four relevant groups: (A) tile setters and terrazzo workers (incidence per 10 000 employees = 19.9); (B) painters (7.8); (C) construction and cement workers (5.2); and (D) wood processors (2.6). The overall incidence was 5.1 per 10 000 employees over 10 years, which is a little below average for the entire register (6.7). Of these, 43.6% were at least 40 years old. Allergic contact dermatitis (61.5%) occurred more often than irritant contact dermatitis (44.5%). Potassium dichromate caused roughly half of all cases of sensitization found to be occupationally relevant in the construction industry (152 cases) followed by epoxy resin (40) and cobalt chloride (32).<br /><br /> The results indicate that potassium dichromate is still the most important allergen in the construction industry of Northern Bavaria; there has been no significant decline during the 1990s. This contrasts with the Scandinavian countries, where the prevalence of potassium dichromate sensitization declined following the reduction of chromium VI levels resulting from the addition of ferrous sulphate to cement. Within the construction industry, tile setters and terrazzo workers have a strikingly high incidence of OSD.","Occupational skin disease in the construction industry Abs: Construction workers have a substantial risk of developing irritant and/or allergic contact dermatitis. Unfortunately, however, there is little population-based epidemiological data relating to occupational skin diseases (OSD) in the European construction industry that allow assessment of preventive measures.<br /><br /> In this investigation, the yearly incidence rates and causes of OSD in the construction industry were analysed on the basis of our register in Northern Bavaria.<br /><br /> From 1990 until 1999, all incidences of OSD in the construction industry were recorded prospectively. This enables the calculation of incidence rates of OSD in relation to the employed population in Northern Bavaria as recorded by the German Federal Employment Office.<br /><br /> In the construction industry, a total of 335 OSD were registered. These comprise 9.0% of all OSD in the register. We classified them into four relevant groups: (A) tile setters and terrazzo workers (incidence per 10 000 employees = 19.9); (B) painters (7.8); (C) construction and cement workers (5.2); and (D) wood processors (2.6). The overall incidence was 5.1 per 10 000 employees over 10 years, which is a little below average for the entire register (6.7). Of these, 43.6% were at least 40 years old. Allergic contact dermatitis (61.5%) occurred more often than irritant contact dermatitis (44.5%). Potassium dichromate caused roughly half of all cases of sensitization found to be occupationally relevant in the construction industry (152 cases) followed by epoxy resin (40) and cobalt chloride (32).<br /><br /> The results indicate that potassium dichromate is still the most important allergen in the construction industry of Northern Bavaria; there has been no significant decline during the 1990s. This contrasts with the Scandinavian countries, where the prevalence of potassium dichromate sensitization declined following the reduction of chromium VI levels resulting from the addition of ferrous sulphate to cement. Within the construction industry, tile setters and terrazzo workers have a strikingly high incidence of OSD."
736114,Greig et al. 2000,Prevalence of delayed hypersensitivity to the European standard series in a self-selected population,"There are limited reports of the prevalence of positive reactions in healthy adults to patch tests with standard allergens; there are no recent comprehensive studies from Australia. Healthy adult volunteers (n = 219) from the Western Australian community were patch tested using the European standard series of allergens. Seventy-seven (35%) reacted to at least one allergen, positive patch tests being most prevalent to nickel sulfate (20%), potassium dichromate (9%), cobalt chloride (6%) and fragrance mix (4%). Prevalence of positive patch tests to nickel and chromate was higher than that reported for another healthy population, which may stem from self-selection of volunteers or geographical differences, including extent of exposure to allergens.","Prevalence of delayed hypersensitivity to the European standard series in a self-selected population Abs: There are limited reports of the prevalence of positive reactions in healthy adults to patch tests with standard allergens; there are no recent comprehensive studies from Australia. Healthy adult volunteers (n = 219) from the Western Australian community were patch tested using the European standard series of allergens. Seventy-seven (35%) reacted to at least one allergen, positive patch tests being most prevalent to nickel sulfate (20%), potassium dichromate (9%), cobalt chloride (6%) and fragrance mix (4%). Prevalence of positive patch tests to nickel and chromate was higher than that reported for another healthy population, which may stem from self-selection of volunteers or geographical differences, including extent of exposure to allergens."
736113,Fowler et al. 1999,An environmental hazard assessment of low-level dermal exposure to hexavalent chromium in solution among chromium-sensitized volunteers,"To evaluate the potential for elicitation of allergic contact dermatitis from contact with standing water in the environment, 26 persons known to be allergic to hexavalent chromium [Cr(VI)] were exposed to 25 to 29 mg/L Cr(VI) by immersion of one arm for 30 minutes per day on 3 consecutive days in a potassium dichromate bath. Sixteen of the 26 volunteers demonstrated either no or an equivocal response to the Cr(VI) challenge. Ten of the volunteers developed a few papules or vesicles (1 to approximately 15), mild redness, and pruritus on the Cr(VI)-challenged arm. Histopathological examination of the papules revealed spongiosis and perieccrine and perivascular inflammation. The responses were diagnosed as acute perieccrine reactions. It was concluded that exposure to similar concentrations of Cr(VI) in the environment does not pose an allergic contact dermatitis hazard, even to Cr-sensitized persons.","An environmental hazard assessment of low-level dermal exposure to hexavalent chromium in solution among chromium-sensitized volunteers Abs: To evaluate the potential for elicitation of allergic contact dermatitis from contact with standing water in the environment, 26 persons known to be allergic to hexavalent chromium [Cr(VI)] were exposed to 25 to 29 mg/L Cr(VI) by immersion of one arm for 30 minutes per day on 3 consecutive days in a potassium dichromate bath. Sixteen of the 26 volunteers demonstrated either no or an equivocal response to the Cr(VI) challenge. Ten of the volunteers developed a few papules or vesicles (1 to approximately 15), mild redness, and pruritus on the Cr(VI)-challenged arm. Histopathological examination of the papules revealed spongiosis and perieccrine and perivascular inflammation. The responses were diagnosed as acute perieccrine reactions. It was concluded that exposure to similar concentrations of Cr(VI) in the environment does not pose an allergic contact dermatitis hazard, even to Cr-sensitized persons."
736112,Kosann et al. 1998,Six-hour versus 48-hour patch testing with varying concentrations of potassium dichromate,"This study examines the possibility of using patch contact times shorter in duration than the standard 48 hours. Using varying concentrations of potassium dichromate (K2Cr2O7), this study analyzed results from two sets of patches applied to the backs of 11 subjects for durations of 6 and 48 hours, respectively. Results showed that after the 48-hour application period, all subjects reacted to K2Cr2O7 at some concentration. For the patches applied for 6 hours, 7 of the 11 subjects (64%) reacted to K2Cr2O7 at some concentration. Minimum elicitation thresholds (METs), the lowest concentration at which a reaction was observed, were established for both the 6-hour and 48-hour application times. The ratio of an individual's 6-hour MET to their 48-hour MET was calculated to evaluate the feasibility of patch testing with a higher concentration of an allergen for a shorter time period. Although the results clearly indicated that a higher concentration of allergen is required in order to elicit a reaction at 6 versus 48 hours, a fair amount of interindividual variability is exhibited by these 6-hour to 48-hour MET ratios. This observed variability would seem to preclude the use of 6-hour duration patch contact times for routine patch testing with K2Cr2O7.","Six-hour versus 48-hour patch testing with varying concentrations of potassium dichromate Abs: This study examines the possibility of using patch contact times shorter in duration than the standard 48 hours. Using varying concentrations of potassium dichromate (K2Cr2O7), this study analyzed results from two sets of patches applied to the backs of 11 subjects for durations of 6 and 48 hours, respectively. Results showed that after the 48-hour application period, all subjects reacted to K2Cr2O7 at some concentration. For the patches applied for 6 hours, 7 of the 11 subjects (64%) reacted to K2Cr2O7 at some concentration. Minimum elicitation thresholds (METs), the lowest concentration at which a reaction was observed, were established for both the 6-hour and 48-hour application times. The ratio of an individual's 6-hour MET to their 48-hour MET was calculated to evaluate the feasibility of patch testing with a higher concentration of an allergen for a shorter time period. Although the results clearly indicated that a higher concentration of allergen is required in order to elicit a reaction at 6 versus 48 hours, a fair amount of interindividual variability is exhibited by these 6-hour to 48-hour MET ratios. This observed variability would seem to preclude the use of 6-hour duration patch contact times for routine patch testing with K2Cr2O7."
736111,Sharma and  Chakrabarti 1998,"Common contact sensitizers in Chandigarh, India. A study of 200 patients with the European standard series","200 patients (122 male, 78 female) with suspected allergic contact dermatitis were patch tested with the European standard series (ESS) and the results compared with other Asian centres. 131 (65.5%) patients showed 1 or more patch test positives to the ESS. Patch tests were positive to all allergens except primin. Potassium dichromate was the most common allergen (20.5%) followed by nickel sulfate (16.5%), SQL mix (14%), PPD (11.5%), cobalt (8%), fragrance mix (7.5%), formaldehyde (6.5%), colophony (5.5%), neomycin sulfate and mercapto mix (5% each). In women, nickel sulfate was the commonest allergen (30.8%) followed by SQL mix (16.7%) and potassium dichromate (15.4%). In men, potassium dichromate was the commonest sensitizer (23.8%) followed by SQL mix and PPD (12.3% each). Our results are at variance with other centres in Asia. SQL mix was able to detect less than 1/2 (42.2%) of patients allergic to ethanolic dilutions of ether extracts of parthenium. We conclude that the European standard series, with exclusion of primin, is suitable for detection of allergic contact dermatitis in India. However, SQL mix is not a adequate screen for parthenium sensitivity and patch testing with extracts of the plant should be continued, wherever indicated.","Common contact sensitizers in Chandigarh, India. A study of 200 patients with the European standard series Abs: 200 patients (122 male, 78 female) with suspected allergic contact dermatitis were patch tested with the European standard series (ESS) and the results compared with other Asian centres. 131 (65.5%) patients showed 1 or more patch test positives to the ESS. Patch tests were positive to all allergens except primin. Potassium dichromate was the most common allergen (20.5%) followed by nickel sulfate (16.5%), SQL mix (14%), PPD (11.5%), cobalt (8%), fragrance mix (7.5%), formaldehyde (6.5%), colophony (5.5%), neomycin sulfate and mercapto mix (5% each). In women, nickel sulfate was the commonest allergen (30.8%) followed by SQL mix (16.7%) and potassium dichromate (15.4%). In men, potassium dichromate was the commonest sensitizer (23.8%) followed by SQL mix and PPD (12.3% each). Our results are at variance with other centres in Asia. SQL mix was able to detect less than 1/2 (42.2%) of patients allergic to ethanolic dilutions of ether extracts of parthenium. We conclude that the European standard series, with exclusion of primin, is suitable for detection of allergic contact dermatitis in India. However, SQL mix is not a adequate screen for parthenium sensitivity and patch testing with extracts of the plant should be continued, wherever indicated."
736110,El Samahy and  El-Kerdani 1997,Value of patch testing in atopic dermatitis,"Because patients with atopic dermatitis are less prone to type IV allergies, there has been controversy regarding the role of patch testing in these patients.<br /><br /> The present study was conducted to evaluate the role of patch testing in atopic individuals.<br /><br /> One-hundred patients with hand eczema were patch tested using the standard patch test battery (HERMAL, Kurt Herrmann, Reinbek, West Germany) and the Finn chamber units. The total immunoglobulin class E (IgE) level was determined and correlated to the results of patch testing.<br /><br /> Eighty-seven patients had positive patch test reactions. Among the 87 patients, 39 (44.8%) had atopic dermatitis. The most common allergens yielding positive results were nickel sulfate, 2.5%, (58.6%); potassium dichromate, 0.25% (56.3%); carba mix, 3%, (44.82%); formaldehyde, 1% in H2O, (40.22%); neomycin sulfate, 20%, (33.3%); and balsam of Peru 25%, (17.24%) respectively. Patients with atopic dermatitis were more frequently sensitive to neomycin sulfate than nonatopics.<br /><br /> Patients with atopic dermatitis should be patch tested when indicated because they also develop contact allergic sensitization to a significant degree. Our observations indicate that patch testing with standard allergens often adds valuable information about contact sensitivity in these patients.","Value of patch testing in atopic dermatitis Abs: Because patients with atopic dermatitis are less prone to type IV allergies, there has been controversy regarding the role of patch testing in these patients.<br /><br /> The present study was conducted to evaluate the role of patch testing in atopic individuals.<br /><br /> One-hundred patients with hand eczema were patch tested using the standard patch test battery (HERMAL, Kurt Herrmann, Reinbek, West Germany) and the Finn chamber units. The total immunoglobulin class E (IgE) level was determined and correlated to the results of patch testing.<br /><br /> Eighty-seven patients had positive patch test reactions. Among the 87 patients, 39 (44.8%) had atopic dermatitis. The most common allergens yielding positive results were nickel sulfate, 2.5%, (58.6%); potassium dichromate, 0.25% (56.3%); carba mix, 3%, (44.82%); formaldehyde, 1% in H2O, (40.22%); neomycin sulfate, 20%, (33.3%); and balsam of Peru 25%, (17.24%) respectively. Patients with atopic dermatitis were more frequently sensitive to neomycin sulfate than nonatopics.<br /><br /> Patients with atopic dermatitis should be patch tested when indicated because they also develop contact allergic sensitization to a significant degree. Our observations indicate that patch testing with standard allergens often adds valuable information about contact sensitivity in these patients."
736109,Zachariae et al. 1996,Chromium allergy in consecutive patients in a country where ferrous sulfate has been added to cement since 1981,"Cement eczema used to be a common occupational disease in Denmark. Since 1981, ferrous sulfate has been added to all cement produced in Denmark to reduce the amount of soluble hexavalent chromate to below 2 mg/kg (2 ppm). The aim of the study was to analyse a material of consecutive chromate-sensitive patients in an urban tertiary referral centre with respect to primary cause of sensitization, in a geographical area where the risk of chromate exposure from cement had been reduced. In the 6-year period January 1989 to December 1994, a total of 4511 patients were patch tested with the European standard series, including chromate. 79 patients, 31 male and 48 female, were diagnosed as chromate sensitive. Relevant chromate exposure was established in 34 of these 79 patients. Leather was the most frequent source of chromate sensitization (19 out of 34) (47%). Chromate sensitization from cement was considered likely in 10 out of 34 subjects. Of these, 7 had been sensitized before 1981, 2 had been sensitized by non-occupational exposure to cement, and only 1 had been sensitized from occupational cement exposure in the 6-year period.","Chromium allergy in consecutive patients in a country where ferrous sulfate has been added to cement since 1981 Abs: Cement eczema used to be a common occupational disease in Denmark. Since 1981, ferrous sulfate has been added to all cement produced in Denmark to reduce the amount of soluble hexavalent chromate to below 2 mg/kg (2 ppm). The aim of the study was to analyse a material of consecutive chromate-sensitive patients in an urban tertiary referral centre with respect to primary cause of sensitization, in a geographical area where the risk of chromate exposure from cement had been reduced. In the 6-year period January 1989 to December 1994, a total of 4511 patients were patch tested with the European standard series, including chromate. 79 patients, 31 male and 48 female, were diagnosed as chromate sensitive. Relevant chromate exposure was established in 34 of these 79 patients. Leather was the most frequent source of chromate sensitization (19 out of 34) (47%). Chromate sensitization from cement was considered likely in 10 out of 34 subjects. Of these, 7 had been sensitized before 1981, 2 had been sensitized by non-occupational exposure to cement, and only 1 had been sensitized from occupational cement exposure in the 6-year period."
736003,Pellerin and  Booker 2000,Reflections on hexavalent chromium: Health hazards of an industrial heavyweight,"Chromium has been used commercially in the United States for more than 100 years in metal alloys and other compounds, as a pigment, and in the tanning and metal plating industries, and many studies have looked at its effects in terms of occupational health. But, although scientists know that Cr(VI) is a human carcinogen and that it can cause other deleterious health effects including kidney and liver damage, certain questions remain about the metal's effects, such as which routes of exposures are dangerous for humans.","Reflections on hexavalent chromium: Health hazards of an industrial heavyweight Abs: Chromium has been used commercially in the United States for more than 100 years in metal alloys and other compounds, as a pigment, and in the tanning and metal plating industries, and many studies have looked at its effects in terms of occupational health. But, although scientists know that Cr(VI) is a human carcinogen and that it can cause other deleterious health effects including kidney and liver damage, certain questions remain about the metal's effects, such as which routes of exposures are dangerous for humans."
735980,James et al. 1997,Oxidation-reduction chemistry of chromium: Relevance to the regulation and remediation of chromate-contaminated soils,"Developing health-protective clean-up standards and remediation strategies for chromium-contaminated soils based on the hexavalent forms of this heavy metal is a complex and controversial issue, because certain forms of Cr(III) can oxidize to Cr(VI) and Cr(VI) can be reduced to Cr(III) under diverse soil conditions. The extent of oxidation of Cr(III) in soils amended with wastes is based on four interacting parameters: (1) solubility and form of Cr(III) related to oxidation (waste oxidation potential, or WOP), (2) reactive soil Mn(III,IV) (hydr)oxide levels (soil oxidation potential for Cr(III), or SOP), (3) soil potential for Cr(VI) reduction (soil reduction potential, or SRP), and (4) soil-waste pH as a modifier of the first three parameters (pH modification value, or PMV). Each of these four parameters can be quantified with laboratory tests and ranked numerically; the sum of which is the Potential Chromium Oxidation Score (PCOS) for assessing the relative hazard of a waste-soil combination. The PCOS value is proposed as the basis for setting acceptable maximum limits for Cr(III)-containing wastes in particular soil environments to maintain Cr(VI) levels at or below health-based limits. Adjusting and controlling the PCOS parameters will allow practitioners to design remediation strategies and regulators to establish Cr clean-up standards under soil conditions that minimize Cr(III) oxidation and maximize Cr(VI) reduction. Effective remediation of Cr(VI)-Contaminated soils by reduction depends on three principles: (1) reduction of Cr(VI) to forms of Cr(III) that are inert toward re- oxidation, (2) the absence of undesirable reaction products (e.g., the oxidized forms of certain reducing agents), and (3) establishment or maintenance of soil pH and Eh conditions that favor reduction of Cr(VI) and disfavor the oxidation of Cr(III). This article focuses on the importance of understanding the waste forms of Cr and the redox-related properties of Cr-contaminated soils in the design of remedial goals to protect human health and ecological function.","Oxidation-reduction chemistry of chromium: Relevance to the regulation and remediation of chromate-contaminated soils Abs: Developing health-protective clean-up standards and remediation strategies for chromium-contaminated soils based on the hexavalent forms of this heavy metal is a complex and controversial issue, because certain forms of Cr(III) can oxidize to Cr(VI) and Cr(VI) can be reduced to Cr(III) under diverse soil conditions. The extent of oxidation of Cr(III) in soils amended with wastes is based on four interacting parameters: (1) solubility and form of Cr(III) related to oxidation (waste oxidation potential, or WOP), (2) reactive soil Mn(III,IV) (hydr)oxide levels (soil oxidation potential for Cr(III), or SOP), (3) soil potential for Cr(VI) reduction (soil reduction potential, or SRP), and (4) soil-waste pH as a modifier of the first three parameters (pH modification value, or PMV). Each of these four parameters can be quantified with laboratory tests and ranked numerically; the sum of which is the Potential Chromium Oxidation Score (PCOS) for assessing the relative hazard of a waste-soil combination. The PCOS value is proposed as the basis for setting acceptable maximum limits for Cr(III)-containing wastes in particular soil environments to maintain Cr(VI) levels at or below health-based limits. Adjusting and controlling the PCOS parameters will allow practitioners to design remediation strategies and regulators to establish Cr clean-up standards under soil conditions that minimize Cr(III) oxidation and maximize Cr(VI) reduction. Effective remediation of Cr(VI)-Contaminated soils by reduction depends on three principles: (1) reduction of Cr(VI) to forms of Cr(III) that are inert toward re- oxidation, (2) the absence of undesirable reaction products (e.g., the oxidized forms of certain reducing agents), and (3) establishment or maintenance of soil pH and Eh conditions that favor reduction of Cr(VI) and disfavor the oxidation of Cr(III). This article focuses on the importance of understanding the waste forms of Cr and the redox-related properties of Cr-contaminated soils in the design of remedial goals to protect human health and ecological function."
735979,Barceloux and  Barceloux 1999,Chromium,"Chromium occurs primarily in the trivalent state (III), which is the most stable form, or in the hexavalent state (VI), which is a strong oxidizing agent. Elemental chromium (0) does not occur naturally on earth. Trivalent chromium (III) is an essential trace metal necessary for the formation of glucose tolerance factor and for the metabolism of insulin. Commercial applications of chromium compounds include tanning (III), corrosion inhibition, plating, glassware-cleaning solutions, wood preservatives (VI), manufacture of safety matches, metal finishing (VI), and the production of pigments (III, VI). Hexavalent chromium (VI) contaminated local soil when chromium waste slag was part of the fill material present in residential, public, and industrial areas. In some urban areas, about two-thirds of the chromium in air results from the emission of hexavalent chromium from fossil fuel combustion and steel production. The remaining chromium in air is the trivalent form. The residence time of chromium in air is <10 days, depending on the particle size. Trivalent compounds generally have low toxicity and the gastrointestinal tract poorly absorbs these compounds. Hexavalent chromium is a skin and mucous membrane irritant and some of these hexavalent compounds are strong corrosive agents. Hexavalent chromium compounds also produce an allergic contact dermatitis characterized by eczema. Sensitivity to trivalent compounds is much less frequent, but some workers may react to high concentrations of these compounds. Hexavalent chromium is recognized by the International Agency for Research on Cancer and by the US Toxicology Program as a pulmonary carcinogen. The increased risk of lung cancer occurs primarily in workers exposed to hexavalent chromium dust during the refining of chromite ore and the production of chromate pigments. Although individual studies suggest the possibility of an excess incidence of cancer at sites outside the lung, the results from these studies are inconsistent.","Chromium Abs: Chromium occurs primarily in the trivalent state (III), which is the most stable form, or in the hexavalent state (VI), which is a strong oxidizing agent. Elemental chromium (0) does not occur naturally on earth. Trivalent chromium (III) is an essential trace metal necessary for the formation of glucose tolerance factor and for the metabolism of insulin. Commercial applications of chromium compounds include tanning (III), corrosion inhibition, plating, glassware-cleaning solutions, wood preservatives (VI), manufacture of safety matches, metal finishing (VI), and the production of pigments (III, VI). Hexavalent chromium (VI) contaminated local soil when chromium waste slag was part of the fill material present in residential, public, and industrial areas. In some urban areas, about two-thirds of the chromium in air results from the emission of hexavalent chromium from fossil fuel combustion and steel production. The remaining chromium in air is the trivalent form. The residence time of chromium in air is <10 days, depending on the particle size. Trivalent compounds generally have low toxicity and the gastrointestinal tract poorly absorbs these compounds. Hexavalent chromium is a skin and mucous membrane irritant and some of these hexavalent compounds are strong corrosive agents. Hexavalent chromium compounds also produce an allergic contact dermatitis characterized by eczema. Sensitivity to trivalent compounds is much less frequent, but some workers may react to high concentrations of these compounds. Hexavalent chromium is recognized by the International Agency for Research on Cancer and by the US Toxicology Program as a pulmonary carcinogen. The increased risk of lung cancer occurs primarily in workers exposed to hexavalent chromium dust during the refining of chromite ore and the production of chromate pigments. Although individual studies suggest the possibility of an excess incidence of cancer at sites outside the lung, the results from these studies are inconsistent."
735969,Kerger et al. 1996,Refined exposure assessment for ingestion of tapwater contaminated with hexavalent chromium: Consideration of exogenous and endogenous reducing agents,"Laboratory studies were conducted to determine how rapidly and completely chromium (VI) [Cr(VI)] is reduced upon contact with common beverages mixed with tapwater. Studies were performed for five common beverages (coffee, tea, orange juice, Kool Aid, and powdered lemonade) spiked with either 10 or 50 mg Cr(VI)/l. The concentrations of Cr(VI) were measured at several time intervals for up to four hours. It was demonstrated that each of these beverages had the capacity to reduce a concentration of > or = 8 mg Cr(VI)/l within a 15-minute time frame, and that continued monitoring of the beverages revealed greater reduction of the Cr(VI). These findings are consistent with the observation that many foods and beverages, as well as endogenous body fluids such as saliva and gastric juices, are capable of reducing substantial quantities of Cr(VI) to Cr(III). Our exposure assessment shows that the estimated high-end ingested dose of Cr(VI) from tapwater at both 1 and 5 mg Cr(VI)/l is generally two to three orders of magnitude below doses shown to have no adverse health effect in animal studies. When considered in conjunction with studies demonstrating that the reductive capacity of gastric juices may exceed 50 mg Cr(VI) daily, these observations suggest that little or no Cr(VI) is likely to be absorbed orally at a reasonable water concentration of Cr(VI), since tapwater is bright yellow at 5 mg Cr(VI)/l.","Refined exposure assessment for ingestion of tapwater contaminated with hexavalent chromium: Consideration of exogenous and endogenous reducing agents Abs: Laboratory studies were conducted to determine how rapidly and completely chromium (VI) [Cr(VI)] is reduced upon contact with common beverages mixed with tapwater. Studies were performed for five common beverages (coffee, tea, orange juice, Kool Aid, and powdered lemonade) spiked with either 10 or 50 mg Cr(VI)/l. The concentrations of Cr(VI) were measured at several time intervals for up to four hours. It was demonstrated that each of these beverages had the capacity to reduce a concentration of > or = 8 mg Cr(VI)/l within a 15-minute time frame, and that continued monitoring of the beverages revealed greater reduction of the Cr(VI). These findings are consistent with the observation that many foods and beverages, as well as endogenous body fluids such as saliva and gastric juices, are capable of reducing substantial quantities of Cr(VI) to Cr(III). Our exposure assessment shows that the estimated high-end ingested dose of Cr(VI) from tapwater at both 1 and 5 mg Cr(VI)/l is generally two to three orders of magnitude below doses shown to have no adverse health effect in animal studies. When considered in conjunction with studies demonstrating that the reductive capacity of gastric juices may exceed 50 mg Cr(VI) daily, these observations suggest that little or no Cr(VI) is likely to be absorbed orally at a reasonable water concentration of Cr(VI), since tapwater is bright yellow at 5 mg Cr(VI)/l."
735968,Blade et al. 2007,Hexavalent chromium exposures and exposure-control technologies in American enterprise: results of a NIOSH field research study,"The National Institute for Occupational Safety and Health (NIOSH) conducted 21 field surveys in selected industries to characterize workers' exposures to hexavalent chromium-containing airborne particulate and to evaluate existing technologies for controlling these exposures. Hexavalent chromium Cr(VI) is a respiratory irritant and chronic inhalation may cause lung cancer. Primary evaluation methods included collection of full work shift, personal breathing-zone (PBZ) air samples for Cr(VI), measurement of ventilation system parameters, and documentation of processes and work practices. This study emphasized evaluation of engineering exposure control measures, so PBZ exposures were measured on the outside of personal protective equipment, for example, respirators. Field surveys were conducted in two chromium electroplating facilities, including one where full-shift PBZ exposures to Cr(VI) ranged from 3.0 to 16 times the 1 micro g/m(3)NIOSH recommended exposure limit (REL) despite several engineering controls on the plating tanks. At a painting and coating facility that used Cr(VI)-containing products, full-shift exposures of painters and helpers (2.4 to 55 micro g/m(3)) exceeded the REL, but LEV effectiveness was limited. Other operations evaluated included welding in construction; metal cutting operations on chromium-containing materials in ship breaking; chromate-paint removal with abrasive blasting; atomized alloy-spray coating; foundry operations; printing; and the manufacture of refractory brick, colored glass, prefabricated concrete products, and treated wood products. NIOSH researchers concluded that, in many of the evaluated processes, Cr(VI) exposures at or below the current NIOSH REL are achievable. However, for some processes, it is unclear whether controlling exposures to this range is consistently achievable without respirator use. Some operations involving the application of coatings and finishes may be among those most difficult to control to this range. Most operations judged to be moderately difficult to control to this range involve joining and cutting metals with relatively high chromium content. Nonetheless, exposures in a wide variety of other processes were judged more easily controllable to the current REL or below, or were found to be minimal, including some operations meeting the general descriptions named above but with different specific operating parameters producing lower Cr(VI) exposures.","Hexavalent chromium exposures and exposure-control technologies in American enterprise: results of a NIOSH field research study Abs: The National Institute for Occupational Safety and Health (NIOSH) conducted 21 field surveys in selected industries to characterize workers' exposures to hexavalent chromium-containing airborne particulate and to evaluate existing technologies for controlling these exposures. Hexavalent chromium Cr(VI) is a respiratory irritant and chronic inhalation may cause lung cancer. Primary evaluation methods included collection of full work shift, personal breathing-zone (PBZ) air samples for Cr(VI), measurement of ventilation system parameters, and documentation of processes and work practices. This study emphasized evaluation of engineering exposure control measures, so PBZ exposures were measured on the outside of personal protective equipment, for example, respirators. Field surveys were conducted in two chromium electroplating facilities, including one where full-shift PBZ exposures to Cr(VI) ranged from 3.0 to 16 times the 1 micro g/m(3)NIOSH recommended exposure limit (REL) despite several engineering controls on the plating tanks. At a painting and coating facility that used Cr(VI)-containing products, full-shift exposures of painters and helpers (2.4 to 55 micro g/m(3)) exceeded the REL, but LEV effectiveness was limited. Other operations evaluated included welding in construction; metal cutting operations on chromium-containing materials in ship breaking; chromate-paint removal with abrasive blasting; atomized alloy-spray coating; foundry operations; printing; and the manufacture of refractory brick, colored glass, prefabricated concrete products, and treated wood products. NIOSH researchers concluded that, in many of the evaluated processes, Cr(VI) exposures at or below the current NIOSH REL are achievable. However, for some processes, it is unclear whether controlling exposures to this range is consistently achievable without respirator use. Some operations involving the application of coatings and finishes may be among those most difficult to control to this range. Most operations judged to be moderately difficult to control to this range involve joining and cutting metals with relatively high chromium content. Nonetheless, exposures in a wide variety of other processes were judged more easily controllable to the current REL or below, or were found to be minimal, including some operations meeting the general descriptions named above but with different specific operating parameters producing lower Cr(VI) exposures."
735967,Fryzek et al. 2001,Cancer mortality in relation to environmental chromium exposure,"From the 1950s to the 1980s, hexavalent chromium compounds were used as additives at certain water-cooling towers at three southern California gas compressor facilities. Claims of potential residential chromium exposure prompted the examination of age-adjusted mortality rates during 1989 to 1998 for lung cancer, all cancer, and all deaths for neighborhoods near versus distant from the plants. Differences in the rates between areas tended to be small and not statistically significant. The only significant difference was a lower, rather than higher, rate of total cancer among women in the potentially exposed areas. Study limitations preclude a definitive assessment of risk, but similar to previous investigations of cancer in relation to environmental chromium exposure in other locations, this study found no evidence of a cancer hazard among residents living near these California gas compressor facilities.","Cancer mortality in relation to environmental chromium exposure Abs: From the 1950s to the 1980s, hexavalent chromium compounds were used as additives at certain water-cooling towers at three southern California gas compressor facilities. Claims of potential residential chromium exposure prompted the examination of age-adjusted mortality rates during 1989 to 1998 for lung cancer, all cancer, and all deaths for neighborhoods near versus distant from the plants. Differences in the rates between areas tended to be small and not statistically significant. The only significant difference was a lower, rather than higher, rate of total cancer among women in the potentially exposed areas. Study limitations preclude a definitive assessment of risk, but similar to previous investigations of cancer in relation to environmental chromium exposure in other locations, this study found no evidence of a cancer hazard among residents living near these California gas compressor facilities."
735966,Paustenbach et al. 1997,Urinary chromium as a biological marker of environmental exposure: What are the limitations,"Public concern has mounted recently about environmental exposures to chromium in soil, tap water, and ambient air. In response, agencies charged with protecting public health have attempted to study exposure by monitoring urinary chromium levels among potentially exposed populations. While urinary biomonitoring of occupationally exposed workers has been successfully used to assess high-level inhalation exposures in the workplace, evaluating low-level environmental exposures has been problematic. Due to these problems, before an extensive biological monitoring study is conducted of those exposed to low levels of environmental chromium, several issues must be resolved. First, exposures to chromium must occur at the same time as sampling, because the biological half-life of chromium in urine is very short (less than 2 days). Second, reduced bioavailability and bioaccessibility via the oral and dermal routes of exposure limit the capacity of urinary monitoring to measure environmental exposures (e.g., systemic dose is too small to be measured). Third, the dose of chromium must be sufficient such that it may be reliably measured above background levels in urine (range of 0.2 to 2 microg/liter) and above the analytical limit of detection (0.2 microg/liter). Fourth, the inter- and intrapersonal variability in background levels of urinary chromium is known to be significant and influenced by food and beverage intake, smoking, and exercise. Thus, the role of each factor must be carefully understood. Finally, it is imperative to have developed a complete understanding of the clinical significance of elevated urinary chromium levels before a study is performed, because higher than background levels, in and of themselves, are not indicative of a significant health concern. The route of exposure, valence of chromium to which people were exposed, exposure time, and duration must all be understood before the biological data can be implemented. We have conducted a total of nine human exposure studies over the past 3 years in an attempt to understand the kinetics of chromium and the impact on urinary, red blood cell (RBC), and plasma biomonitoring programs. The results of these studies are described here and our recommendations are offered for how to design and implement a urinary chromium biomonitoring study. In our view, given some evidence that the dose of hexavalent chromium [Cr(VI)] is sufficient to be measurable above background concentrations of total chromium [Cr(III) and Cr(VI)], duplicated measurements of chromium in plasma and RBCs are, in most cases, a more definitive gauge of environmental exposure than urinary biomonitoring.","Urinary chromium as a biological marker of environmental exposure: What are the limitations Abs: Public concern has mounted recently about environmental exposures to chromium in soil, tap water, and ambient air. In response, agencies charged with protecting public health have attempted to study exposure by monitoring urinary chromium levels among potentially exposed populations. While urinary biomonitoring of occupationally exposed workers has been successfully used to assess high-level inhalation exposures in the workplace, evaluating low-level environmental exposures has been problematic. Due to these problems, before an extensive biological monitoring study is conducted of those exposed to low levels of environmental chromium, several issues must be resolved. First, exposures to chromium must occur at the same time as sampling, because the biological half-life of chromium in urine is very short (less than 2 days). Second, reduced bioavailability and bioaccessibility via the oral and dermal routes of exposure limit the capacity of urinary monitoring to measure environmental exposures (e.g., systemic dose is too small to be measured). Third, the dose of chromium must be sufficient such that it may be reliably measured above background levels in urine (range of 0.2 to 2 microg/liter) and above the analytical limit of detection (0.2 microg/liter). Fourth, the inter- and intrapersonal variability in background levels of urinary chromium is known to be significant and influenced by food and beverage intake, smoking, and exercise. Thus, the role of each factor must be carefully understood. Finally, it is imperative to have developed a complete understanding of the clinical significance of elevated urinary chromium levels before a study is performed, because higher than background levels, in and of themselves, are not indicative of a significant health concern. The route of exposure, valence of chromium to which people were exposed, exposure time, and duration must all be understood before the biological data can be implemented. We have conducted a total of nine human exposure studies over the past 3 years in an attempt to understand the kinetics of chromium and the impact on urinary, red blood cell (RBC), and plasma biomonitoring programs. The results of these studies are described here and our recommendations are offered for how to design and implement a urinary chromium biomonitoring study. In our view, given some evidence that the dose of hexavalent chromium [Cr(VI)] is sufficient to be measurable above background concentrations of total chromium [Cr(III) and Cr(VI)], duplicated measurements of chromium in plasma and RBCs are, in most cases, a more definitive gauge of environmental exposure than urinary biomonitoring."
735965,Vitale et al. 1997,"Environmental monitoring of chromium in air, soil, and water","Historical uses of chromium have resulted in its widespread release into the environment. In recent years, a significant amount of research has evaluated the impact of chromium on human health and the environment. Additionally, numerous analytical methods have been developed to identify and quantitate chromium in environmental media in response to various state and federal mandates such as CERCLA, RCRA, CWA, CAA, and SWDA. Due to the significant toxicity differences between trivalent [Cr(III)] and hexavalent [Cr(VI)] chromium, it is essential that chromium be quantified in these two distinct valence states to assess the potential risks to exposure to each in environmental media. Speciation is equally important because of their marked differences in environmental behavior. As the knowledge of risks associated with each valence state has grown and regulatory requirements have evolved, methods to accurately quantitate these species at ever-decreasing concentrations within environmental media have also evolved. This paper addresses the challenges of chromium species quantitation and some of the most relevant current methods used for environmental monitoring, including ASTM Method D5281 for air, SW-846 Methods 3060A, 7196A and 7199 for soils, sediments, and waste, and U.S. EPA Method 218.6 for water.","Environmental monitoring of chromium in air, soil, and water Abs: Historical uses of chromium have resulted in its widespread release into the environment. In recent years, a significant amount of research has evaluated the impact of chromium on human health and the environment. Additionally, numerous analytical methods have been developed to identify and quantitate chromium in environmental media in response to various state and federal mandates such as CERCLA, RCRA, CWA, CAA, and SWDA. Due to the significant toxicity differences between trivalent [Cr(III)] and hexavalent [Cr(VI)] chromium, it is essential that chromium be quantified in these two distinct valence states to assess the potential risks to exposure to each in environmental media. Speciation is equally important because of their marked differences in environmental behavior. As the knowledge of risks associated with each valence state has grown and regulatory requirements have evolved, methods to accurately quantitate these species at ever-decreasing concentrations within environmental media have also evolved. This paper addresses the challenges of chromium species quantitation and some of the most relevant current methods used for environmental monitoring, including ASTM Method D5281 for air, SW-846 Methods 3060A, 7196A and 7199 for soils, sediments, and waste, and U.S. EPA Method 218.6 for water."
735964,Losi et al. 1994,Environmental biochemistry of chromium,"Chromium is a d-block transitional element with many industrial uses. It occurs naturally in various crustal materials and is discharged to the environment as industrial waste. Although it can occur in a number of oxidation states, only 3+ and 6+ are found in environmental systems. The environmental behavior of Cr is largely a function of its oxidation state. Hexavalent Cr compounds (mainly chromates and dichromates) are considered toxic to a variety of terrestrial and aquatic organisms and are mobile in soil/water systems, much more so than trivalent Cr compounds. This is largely because of differing chemical properties: Hexavalent Cr compounds are strong oxidizers and highly soluble, while trivalent Cr compounds tend to form relatively inert precipitates at near-neutral pH. The trivalent state is generally considered to be the stable form in equilibrium with most soil/water systems. A diagram of the Cr cycle in soils and water is given in Fig. 6 (Bartlett 1991). This illustration provides a summary of environmentally relevant reactions. Beginning with hexavalent Cr that is released into the environment as industrial waste, there are a number of possible fates, including pollution of soil and surface water and leaching into groundwater, where it may remain stable and, in turn, can be taken up by plants or animals, and adsorption/precipitation, involving soil colloids and/or organic matter. Herein lies much of the environmental concern associated with the hexavalent form. A portion of the Cr(VI) will be reduced to the trivalent form by inorganic electron donors, such as Fe2+ and S2-, or by bioprocesses involving organic matter. Following this conversion, Cr3+ can be expected to precipitate as oxides and hydroxides or to form complexes with numerous ligands. This fraction includes a vast majority of global Cr reserves. Soluble Cr3+ complexes, such as those formed with citrate, can undergo oxidation when they come in contact with manganese dioxide, thus reforming hexavalent Cr. In trace amounts, Cr is an essential component of animal nutrition, functioning mainly in glucose metabolism, and possibly in fat metabolism. While shown to be nonessential for plants, it is required by some microbes, possibly as a cofactor for specific enzyme systems. Bacteria with plasmid-conferred resistance to Cr(VI) have been isolated from water, soil, and sediments, and the resistance mechanisms have been somewhat characterized. One of the chief mechanisms is bioreduction of toxic Cr(VI) to the relatively nontoxic Cr(III). This has been shown to occur directly, by enzymatic processes at the cell membrane, and indirectly, with microbially produced H2S acting as the reductant.(ABSTRACT TRUNCATED AT 400 WORDS)","Environmental biochemistry of chromium Abs: Chromium is a d-block transitional element with many industrial uses. It occurs naturally in various crustal materials and is discharged to the environment as industrial waste. Although it can occur in a number of oxidation states, only 3+ and 6+ are found in environmental systems. The environmental behavior of Cr is largely a function of its oxidation state. Hexavalent Cr compounds (mainly chromates and dichromates) are considered toxic to a variety of terrestrial and aquatic organisms and are mobile in soil/water systems, much more so than trivalent Cr compounds. This is largely because of differing chemical properties: Hexavalent Cr compounds are strong oxidizers and highly soluble, while trivalent Cr compounds tend to form relatively inert precipitates at near-neutral pH. The trivalent state is generally considered to be the stable form in equilibrium with most soil/water systems. A diagram of the Cr cycle in soils and water is given in Fig. 6 (Bartlett 1991). This illustration provides a summary of environmentally relevant reactions. Beginning with hexavalent Cr that is released into the environment as industrial waste, there are a number of possible fates, including pollution of soil and surface water and leaching into groundwater, where it may remain stable and, in turn, can be taken up by plants or animals, and adsorption/precipitation, involving soil colloids and/or organic matter. Herein lies much of the environmental concern associated with the hexavalent form. A portion of the Cr(VI) will be reduced to the trivalent form by inorganic electron donors, such as Fe2+ and S2-, or by bioprocesses involving organic matter. Following this conversion, Cr3+ can be expected to precipitate as oxides and hydroxides or to form complexes with numerous ligands. This fraction includes a vast majority of global Cr reserves. Soluble Cr3+ complexes, such as those formed with citrate, can undergo oxidation when they come in contact with manganese dioxide, thus reforming hexavalent Cr. In trace amounts, Cr is an essential component of animal nutrition, functioning mainly in glucose metabolism, and possibly in fat metabolism. While shown to be nonessential for plants, it is required by some microbes, possibly as a cofactor for specific enzyme systems. Bacteria with plasmid-conferred resistance to Cr(VI) have been isolated from water, soil, and sediments, and the resistance mechanisms have been somewhat characterized. One of the chief mechanisms is bioreduction of toxic Cr(VI) to the relatively nontoxic Cr(III). This has been shown to occur directly, by enzymatic processes at the cell membrane, and indirectly, with microbially produced H2S acting as the reductant.(ABSTRACT TRUNCATED AT 400 WORDS)"
735962,Rai et al. 1989,Environmental chemistry of chromium,"The processes that control the environmental chemistry of chromium include redox transformation, precipitation/dissolution, and adsorption/desorption reactions. Commonly occurring reductants, such as ferrous iron and organic material, can transform Cr(VI) to Cr(III), but manganese oxides are the only inorganic oxidants found in the environment that cause the rapid oxidation of Cr(III) to Cr(VI). In the trivalent state, chromium readily forms compounds such as Cr(OH)3 and (Cr,Fe)(OH)3. These solids show amphoteric solubility behavior, with hydroxo complexes being the dominant aqueous species of Cr(III). The relatively low solubilities of Cr(OH)3 and (Cr,Fe)(OH)3 limit Cr(III) concentrations to less than the drinking water limit over much of the pH range of environmental interest. In the hexavalent state, the formation of the Ba(S,Cr)O4 solid solution controls the dissolved chromium concentrations in environments that contain BaSO4. In the absence of solubility-controlling Cr(VI) solids, Cr(VI) concentrations in acidic to slightly alkaline conditions are expected to be limited by adsorption. Iron oxides are the most important absorbents for aqueous Cr(VI) species in most soil environments. Although these processes are complex and interrelated, each must be considered to predict the aqueous concentrations, mobility, and toxicity of chromium in the environment.","Environmental chemistry of chromium Abs: The processes that control the environmental chemistry of chromium include redox transformation, precipitation/dissolution, and adsorption/desorption reactions. Commonly occurring reductants, such as ferrous iron and organic material, can transform Cr(VI) to Cr(III), but manganese oxides are the only inorganic oxidants found in the environment that cause the rapid oxidation of Cr(III) to Cr(VI). In the trivalent state, chromium readily forms compounds such as Cr(OH)3 and (Cr,Fe)(OH)3. These solids show amphoteric solubility behavior, with hydroxo complexes being the dominant aqueous species of Cr(III). The relatively low solubilities of Cr(OH)3 and (Cr,Fe)(OH)3 limit Cr(III) concentrations to less than the drinking water limit over much of the pH range of environmental interest. In the hexavalent state, the formation of the Ba(S,Cr)O4 solid solution controls the dissolved chromium concentrations in environments that contain BaSO4. In the absence of solubility-controlling Cr(VI) solids, Cr(VI) concentrations in acidic to slightly alkaline conditions are expected to be limited by adsorption. Iron oxides are the most important absorbents for aqueous Cr(VI) species in most soil environments. Although these processes are complex and interrelated, each must be considered to predict the aqueous concentrations, mobility, and toxicity of chromium in the environment."
734950,Chou et al. 2007,Chemical-specific health consultation for chromated copper arsenate chemical mixture: Port of Djibouti,"The Agency for Toxic Substances and Disease Registry (ATSDR) prepared this health consultation to provide support for assessing the public health implications of hazardous chemical exposure, primarily through drinking water, related to releases of chromated copper arsenate (CCA) in the port of Djibouti. CCA from a shipment, apparently intended for treating electric poles, is leaking into the soil in the port area. CCA is a pesticide used to protect wood against decay-causing organisms. This mixture commonly contains chromium(VI) (hexavalent chromium) as chromic acid, arsenic(V) (pentavalent arsenic) as arsenic pentoxide and copper (II) (divalent copper) as cupric oxide, often in an aqueous solution or concentrate. Experimental studies of the fate of CCA in soil and monitoring studies of wood-preserving sites where CCA was spilled on the soil indicate that the chromium(VI), arsenic and copper components of CCA can leach from soil into groundwater and surface water. In addition, at CCA wood-preserving sites, substantial concentrations of chromium(VI), arsenic and copper remained in the soil and were leachable into water four years after the use of CCA was discontinued, suggesting prolonged persistence in soil, with continued potential for leaching. The degree of leaching depended on soil composition and the extent of soil contamination with CCA. In general, leaching was highest for chromium(VI), intermediate for arsenic and lowest for copper. Thus, the potential for contamination of sources of drinking water exists. Although arsenic that is leached from CCA-contaminated soil into surface water may accumulate in the tissues of fish and shellfish, most of the arsenic in these animals will be in a form (often called fish arsenic) that is less harmful. Copper, which leaches less readily than the other components, can accumulate in tissues of mussels and oysters. Chromium is not likely to accumulate in the tissues of fish and shellfish. Limited studies of air concentrations during cleanup of CCA-contaminated soil at wood- preserving sites showed that air levels of chromium(VI), arsenic and copper were below the occupational standards. Workers directly involved in the repackaging, containment or cleanup of leaking containers of CCA or of soil saturated with CCA, however, may be exposed to high levels of CCA through direct dermal contact, inhalation of aerosols or particulates and inadvertent ingestion. Few studies have been conducted on the health effects of CCA. CCA as a concentrated solution is corrosive to the skin eyes and digestive tract. Studies of workers exposed to CCA in wood-preserving plants have not found adverse health effects in these workers, but the studies involved small numbers of workers and therefore are not definitive. People exposed to very high levels of CCA, from sawing wood that still had liquid CCA in it or from living in a home contaminated with ash containing high levels of chromium(VI), arsenic and copper, experienced serious health effects including nosebleeds, digestive system pain and bleeding, itching skin, darkened urine, nervous system effects such as tingling or numbness of the hands and feet and confusion, and rashes or thickening and peeling of the skin. These health effects of the mixture are at least qualitatively reflective of the health effects of the individual components of CCA (arsenic, chromium(VI) and copper). For a given mixture, the critical effects of the individual components are of particular concern, as are any effects in common that may become significant due to additivity or interactions among the components. Effects of concern for CCA, based on the known effects of the individual components, include cancer (arsenic by the oral route, arsenic and chromium(VI) by the inhalation route), irritant or corrosive effects (all three mixture components), the unique dermal effects of arsenic, neurologic effects (arsenic and chromium(VI), and hematologic, hepatic and renal effects (all three components). Because arsenic, chromium(VI), and copper components affect some of the same target organs, they may have additive toxicity toward those organs. Few studies have investigated the potential toxic interactions among the components (arsenic, chromium(VI) and copper) of CCA. The available interaction studies and also possible mechanisms of interaction were evaluated using a weight-of-evidence approach. The conclusion is that there is no strong evidence that interactions among the components of CCA will result in a marked increase in toxicity. This conclusion reflects a lack of well designed interaction studies as well as uncertainties regarding potential mechanisms of interaction. Confidence in the conclusion is low. Workers exposed to high levels of CCA during cleanup of leaking containers of CCA or soil heavily contaminated with CCA should wear protective clothing and respirators if air concentrations of arsenic are above 10 microg/m3. In addition, they should not eat, drink or use tobacco products during exposure to CCA, and should thoroughly wash after skin contact with CCA and before eating, drinking, using tobacco products or using restrooms. When protective clothing becomes contaminated with CCA, it should be changed, and the contaminated clothing should be disposed off in a manner approved for pesticide disposal. Workers should leave all protective clothing, including work shoes and boots, at the workplace, so that CCA will not be carried into their cars and homes, which would endanger other people. People not involved in the cleanup of the CCA and who are not wearing protective clothing should be prevented from entering contaminated areas. Leaking containers of CCA must be repackaged and contained to prevent direct exposure of on-site personnel; and contaminated soil needs to be removed to prevent the CCA from leaching into surface water and groundwater, thereby contaminating sources of drinking water.","Chemical-specific health consultation for chromated copper arsenate chemical mixture: Port of Djibouti Abs: The Agency for Toxic Substances and Disease Registry (ATSDR) prepared this health consultation to provide support for assessing the public health implications of hazardous chemical exposure, primarily through drinking water, related to releases of chromated copper arsenate (CCA) in the port of Djibouti. CCA from a shipment, apparently intended for treating electric poles, is leaking into the soil in the port area. CCA is a pesticide used to protect wood against decay-causing organisms. This mixture commonly contains chromium(VI) (hexavalent chromium) as chromic acid, arsenic(V) (pentavalent arsenic) as arsenic pentoxide and copper (II) (divalent copper) as cupric oxide, often in an aqueous solution or concentrate. Experimental studies of the fate of CCA in soil and monitoring studies of wood-preserving sites where CCA was spilled on the soil indicate that the chromium(VI), arsenic and copper components of CCA can leach from soil into groundwater and surface water. In addition, at CCA wood-preserving sites, substantial concentrations of chromium(VI), arsenic and copper remained in the soil and were leachable into water four years after the use of CCA was discontinued, suggesting prolonged persistence in soil, with continued potential for leaching. The degree of leaching depended on soil composition and the extent of soil contamination with CCA. In general, leaching was highest for chromium(VI), intermediate for arsenic and lowest for copper. Thus, the potential for contamination of sources of drinking water exists. Although arsenic that is leached from CCA-contaminated soil into surface water may accumulate in the tissues of fish and shellfish, most of the arsenic in these animals will be in a form (often called fish arsenic) that is less harmful. Copper, which leaches less readily than the other components, can accumulate in tissues of mussels and oysters. Chromium is not likely to accumulate in the tissues of fish and shellfish. Limited studies of air concentrations during cleanup of CCA-contaminated soil at wood- preserving sites showed that air levels of chromium(VI), arsenic and copper were below the occupational standards. Workers directly involved in the repackaging, containment or cleanup of leaking containers of CCA or of soil saturated with CCA, however, may be exposed to high levels of CCA through direct dermal contact, inhalation of aerosols or particulates and inadvertent ingestion. Few studies have been conducted on the health effects of CCA. CCA as a concentrated solution is corrosive to the skin eyes and digestive tract. Studies of workers exposed to CCA in wood-preserving plants have not found adverse health effects in these workers, but the studies involved small numbers of workers and therefore are not definitive. People exposed to very high levels of CCA, from sawing wood that still had liquid CCA in it or from living in a home contaminated with ash containing high levels of chromium(VI), arsenic and copper, experienced serious health effects including nosebleeds, digestive system pain and bleeding, itching skin, darkened urine, nervous system effects such as tingling or numbness of the hands and feet and confusion, and rashes or thickening and peeling of the skin. These health effects of the mixture are at least qualitatively reflective of the health effects of the individual components of CCA (arsenic, chromium(VI) and copper). For a given mixture, the critical effects of the individual components are of particular concern, as are any effects in common that may become significant due to additivity or interactions among the components. Effects of concern for CCA, based on the known effects of the individual components, include cancer (arsenic by the oral route, arsenic and chromium(VI) by the inhalation route), irritant or corrosive effects (all three mixture components), the unique dermal effects of arsenic, neurologic effects (arsenic and chromium(VI), and hematologic, hepatic and renal effects (all three components). Because arsenic, chromium(VI), and copper components affect some of the same target organs, they may have additive toxicity toward those organs. Few studies have investigated the potential toxic interactions among the components (arsenic, chromium(VI) and copper) of CCA. The available interaction studies and also possible mechanisms of interaction were evaluated using a weight-of-evidence approach. The conclusion is that there is no strong evidence that interactions among the components of CCA will result in a marked increase in toxicity. This conclusion reflects a lack of well designed interaction studies as well as uncertainties regarding potential mechanisms of interaction. Confidence in the conclusion is low. Workers exposed to high levels of CCA during cleanup of leaking containers of CCA or soil heavily contaminated with CCA should wear protective clothing and respirators if air concentrations of arsenic are above 10 microg/m3. In addition, they should not eat, drink or use tobacco products during exposure to CCA, and should thoroughly wash after skin contact with CCA and before eating, drinking, using tobacco products or using restrooms. When protective clothing becomes contaminated with CCA, it should be changed, and the contaminated clothing should be disposed off in a manner approved for pesticide disposal. Workers should leave all protective clothing, including work shoes and boots, at the workplace, so that CCA will not be carried into their cars and homes, which would endanger other people. People not involved in the cleanup of the CCA and who are not wearing protective clothing should be prevented from entering contaminated areas. Leaking containers of CCA must be repackaged and contained to prevent direct exposure of on-site personnel; and contaminated soil needs to be removed to prevent the CCA from leaching into surface water and groundwater, thereby contaminating sources of drinking water."
733760,Gruber and  Jennette 1978,Metabolism of the carcinogen chromate by rat liver microsomes,"The metabolism of chromate by rat liver microsomes has been studied. Incubation of chromate with microsomes in the presence of the enzyme cofactor NADPH, resulted in reduction of chromate. In the absence of NADPH no reduction occurred. Only a small amount of chromate reduction was seen with NADPH in the absence of microsomes. Time course studies, microsome and NADPH concentration dependence studies resulted in conditions giving complete reduction of chromate. The possible relationship of metabolism of chromate to its carcinogenicity and mutagenicity is discussed.","Metabolism of the carcinogen chromate by rat liver microsomes Abs: The metabolism of chromate by rat liver microsomes has been studied. Incubation of chromate with microsomes in the presence of the enzyme cofactor NADPH, resulted in reduction of chromate. In the absence of NADPH no reduction occurred. Only a small amount of chromate reduction was seen with NADPH in the absence of microsomes. Time course studies, microsome and NADPH concentration dependence studies resulted in conditions giving complete reduction of chromate. The possible relationship of metabolism of chromate to its carcinogenicity and mutagenicity is discussed."
733759,Standeven and  Wetterhahn 1992,"Ascorbate is the principal reductant of chromium(VI) in rat lung ultrafiltrates and cytosols, and mediates chromium-DNA binding in vitro","Chromium(VI) reductase activity was measured in ultrafiltrates of rat lung after various pretreatments in vitro at 37 degrees C and pH 7.0. Pretreatment of ultrafiltrates with L-ascorbate oxidase (EC 1.10.3.3), which specifically eliminated ascorbate, blocked approximately 95% of chromium(VI) reductase activity in ultrafiltrates. Preincubation of ultrafiltrates with heat-denatured ascorbate oxidase or the sulfhydryl-blocking agent N-ethylmaleimide (NEM) had no significant effect on Cr(VI) reductase activity. In rat lung cytosols, L-ascorbate oxidase blocked approximately 95% and NEM blocked approximately 15% of Cr(VI) reductase activity. The extent of inhibition of Cr(VI) reductase activity in cytosols by L-ascorbate oxidase was significantly decreased to approximately 75% after addition of 1.0 mM NADPH. When Cr(VI) was incubated with salmon sperm nuclei suspended in rat lung cytosol for 15 min, Cr became bound to nuclear DNA. This Cr-DNA binding was completely inhibited by preincubation of rat lung cytosols with L-ascorbate oxidase and inhibited approximately 60% by preincubation with NEM. Taken together these data suggest that ascorbate and/or ascorbate-dependent factors are the principal reductants of Cr(VI) in both ultrafiltrates and cytosols prepared from rat lung and ascorbate-dependent metabolism of Cr(VI) results in Cr binding to nuclear DNA in vitro. Although sulfhydryl-containing factors and NADPH-dependent factors only make a minor contribution to Cr(VI) reduction in rat lung cytosols, sulfhydryls may be significantly involved in the binding of Cr to nuclear DNA.","Ascorbate is the principal reductant of chromium(VI) in rat lung ultrafiltrates and cytosols, and mediates chromium-DNA binding in vitro Abs: Chromium(VI) reductase activity was measured in ultrafiltrates of rat lung after various pretreatments in vitro at 37 degrees C and pH 7.0. Pretreatment of ultrafiltrates with L-ascorbate oxidase (EC 1.10.3.3), which specifically eliminated ascorbate, blocked approximately 95% of chromium(VI) reductase activity in ultrafiltrates. Preincubation of ultrafiltrates with heat-denatured ascorbate oxidase or the sulfhydryl-blocking agent N-ethylmaleimide (NEM) had no significant effect on Cr(VI) reductase activity. In rat lung cytosols, L-ascorbate oxidase blocked approximately 95% and NEM blocked approximately 15% of Cr(VI) reductase activity. The extent of inhibition of Cr(VI) reductase activity in cytosols by L-ascorbate oxidase was significantly decreased to approximately 75% after addition of 1.0 mM NADPH. When Cr(VI) was incubated with salmon sperm nuclei suspended in rat lung cytosol for 15 min, Cr became bound to nuclear DNA. This Cr-DNA binding was completely inhibited by preincubation of rat lung cytosols with L-ascorbate oxidase and inhibited approximately 60% by preincubation with NEM. Taken together these data suggest that ascorbate and/or ascorbate-dependent factors are the principal reductants of Cr(VI) in both ultrafiltrates and cytosols prepared from rat lung and ascorbate-dependent metabolism of Cr(VI) results in Cr binding to nuclear DNA in vitro. Although sulfhydryl-containing factors and NADPH-dependent factors only make a minor contribution to Cr(VI) reduction in rat lung cytosols, sulfhydryls may be significantly involved in the binding of Cr to nuclear DNA."
733758,Standeven and  Wetterhahn 1991,Ascorbate is the principal reductant of chromium (VI) in rat liver and kidney ultrafiltrates,"Chromium (VI) reductase activity was measured in ultrafiltrates of rat liver and kidney after various pretreatments in vitro at 37 degrees C and pH 7.0. Preincubation of ultrafiltrates with L-ascorbate oxidase (EC 1.10.3.3), which specifically eliminated ascorbate, blocked approximately 80% of the Cr(VI) reductase activity. Heat-denatured ascorbate oxidase had no effect on Cr(VI) reductase activity in ultrafiltrates. Preincubation of ultrafiltrates with N-ethylmaleimide, which non-specifically blocked sulfhydryls, including reduced glutathione, decreased Cr(VI) reductase activity by only 20%. Treatment of male Sprague-Dawley rats with phorone decreased non-protein sulfhydryl (NPSH) levels in rat liver by greater than 90% and tripled reduced ascorbate levels 2 h after treatment. Ultrafiltrates of liver prepared from phorone-treated rats had twice the Cr(VI) reductase activity of control ultrafiltrates, and greater than 95% of this activity could be blocked by preincubation with ascorbate oxidase. Treatment of rats with sodium dichromate (20 mg/kg) caused a significant decrease in ascorbate levels in kidney but not liver, and no change in NPSH levels in kidney or liver, 15 min after treatment. We conclude that ascorbate is the major reductant of Cr(VI) in rat liver and kidney ultrafiltrates and may well be the major non-enzymatic reductant of Cr(VI) in rat liver and kidney in vivo.","Ascorbate is the principal reductant of chromium (VI) in rat liver and kidney ultrafiltrates Abs: Chromium (VI) reductase activity was measured in ultrafiltrates of rat liver and kidney after various pretreatments in vitro at 37 degrees C and pH 7.0. Preincubation of ultrafiltrates with L-ascorbate oxidase (EC 1.10.3.3), which specifically eliminated ascorbate, blocked approximately 80% of the Cr(VI) reductase activity. Heat-denatured ascorbate oxidase had no effect on Cr(VI) reductase activity in ultrafiltrates. Preincubation of ultrafiltrates with N-ethylmaleimide, which non-specifically blocked sulfhydryls, including reduced glutathione, decreased Cr(VI) reductase activity by only 20%. Treatment of male Sprague-Dawley rats with phorone decreased non-protein sulfhydryl (NPSH) levels in rat liver by greater than 90% and tripled reduced ascorbate levels 2 h after treatment. Ultrafiltrates of liver prepared from phorone-treated rats had twice the Cr(VI) reductase activity of control ultrafiltrates, and greater than 95% of this activity could be blocked by preincubation with ascorbate oxidase. Treatment of rats with sodium dichromate (20 mg/kg) caused a significant decrease in ascorbate levels in kidney but not liver, and no change in NPSH levels in kidney or liver, 15 min after treatment. We conclude that ascorbate is the major reductant of Cr(VI) in rat liver and kidney ultrafiltrates and may well be the major non-enzymatic reductant of Cr(VI) in rat liver and kidney in vivo."
733757,Debetto and  Luciani 1988,Toxic effect of chromium on cellular metabolism,"The cytotoxic action of Cr(VI) in intact mammalian cells is strictly related to its carrier-mediated transport across the plasma membrane and its reduction to Cr(III) inside the cell. A marked decrease in the ratio of reduced/oxidized glutathione in rat thymocytes treated with dichromate indicates an involvement of glutathione in the reduction of Cr(VI) to Cr(III) in these cells. Intracellular chromium is shown to interfere with specific steps of cellular energy metabolism in that it produces severe unbalance of purine ribonucleotide pools in hamster fibroblast cultures and inhibition of mitochondrial oxygen consumption in rat thymocytes at micromolar concentrations. To what extent the effects caused by Cr(VI) are directly related to the reduction process or to the subsequent binding of Cr(III), and possibly of Cr(V), to biological molecules playing a critical role in cell physiology, remains to be elucidated.","Toxic effect of chromium on cellular metabolism Abs: The cytotoxic action of Cr(VI) in intact mammalian cells is strictly related to its carrier-mediated transport across the plasma membrane and its reduction to Cr(III) inside the cell. A marked decrease in the ratio of reduced/oxidized glutathione in rat thymocytes treated with dichromate indicates an involvement of glutathione in the reduction of Cr(VI) to Cr(III) in these cells. Intracellular chromium is shown to interfere with specific steps of cellular energy metabolism in that it produces severe unbalance of purine ribonucleotide pools in hamster fibroblast cultures and inhibition of mitochondrial oxygen consumption in rat thymocytes at micromolar concentrations. To what extent the effects caused by Cr(VI) are directly related to the reduction process or to the subsequent binding of Cr(III), and possibly of Cr(V), to biological molecules playing a critical role in cell physiology, remains to be elucidated."
733756,De Flora et al. 1987,Circadian reduction of chromium in the gastric environment,"Samples of gastric juice from variously treated subjects efficiently reduced hexavalent chromium and decreased its mutagenicity. Chromium reduction was due to thermostable components of gastric secretions and was favoured by the acidity of the intragastric environment. The circadian monitoring of pH and of chromium reduction, as assessed by colorimetric analysis at hourly intervals, showed a basal activity (less than 10 micrograms/ml gastric juice) during the night and interdigestive periods, and peaks (tens of micrograms/ml) during the 3-4-h periods after each meal. Assays in the Ames reversion test confirmed that the decrease in mutagenicity of sodium dichromate produced by gastric juice was significantly enhanced after meals. This physiological mechanism is expected to provide an important protective barrier against the oral toxicity of this metal, and may explain its lack of oral carcinogenicity.","Circadian reduction of chromium in the gastric environment Abs: Samples of gastric juice from variously treated subjects efficiently reduced hexavalent chromium and decreased its mutagenicity. Chromium reduction was due to thermostable components of gastric secretions and was favoured by the acidity of the intragastric environment. The circadian monitoring of pH and of chromium reduction, as assessed by colorimetric analysis at hourly intervals, showed a basal activity (less than 10 micrograms/ml gastric juice) during the night and interdigestive periods, and peaks (tens of micrograms/ml) during the 3-4-h periods after each meal. Assays in the Ames reversion test confirmed that the decrease in mutagenicity of sodium dichromate produced by gastric juice was significantly enhanced after meals. This physiological mechanism is expected to provide an important protective barrier against the oral toxicity of this metal, and may explain its lack of oral carcinogenicity."
733755,Wiegand et al. 1985,Fast uptake kinetics in vitro of 51Cr (VI) by red blood cells of man and rat,"Fast transport kinetics of 51Cr (VI) into red blood cells (RBCs) in vitro were studied. No significant species differences were found between RBCs of man and rat. The uptake of 51Cr (VI) by RBCs in whole blood was composed of two different first order processes of different velocities (apparent t 1/2 of 22.7 s and 10.4 min for man and 6.9 s and 10.1 min for rat, respectively). However, even after longer time periods a fixed portion of approximately 15% of the administered dose remained in the plasma and did not penetrate into RBCs Over the entire concentration range studied (10 microM-50 mM), the fast initial uptake followed Michaelis-Menten kinetics. The maximal capacity of this Cr(VI) transport into RBCs of man and rat was 3.1 X 10(8) CrO4(2-) ions X cell-1 X min-1 and 2.5 X 10(8) CrO4(-2) ions X cell-1 X min-1, respectively. It is likely that Cr(VI) is transported into RBCs via a physiological anion carrier (""band-3-protein"").","Fast uptake kinetics in vitro of 51Cr (VI) by red blood cells of man and rat Abs: Fast transport kinetics of 51Cr (VI) into red blood cells (RBCs) in vitro were studied. No significant species differences were found between RBCs of man and rat. The uptake of 51Cr (VI) by RBCs in whole blood was composed of two different first order processes of different velocities (apparent t 1/2 of 22.7 s and 10.4 min for man and 6.9 s and 10.1 min for rat, respectively). However, even after longer time periods a fixed portion of approximately 15% of the administered dose remained in the plasma and did not penetrate into RBCs Over the entire concentration range studied (10 microM-50 mM), the fast initial uptake followed Michaelis-Menten kinetics. The maximal capacity of this Cr(VI) transport into RBCs of man and rat was 3.1 X 10(8) CrO4(2-) ions X cell-1 X min-1 and 2.5 X 10(8) CrO4(-2) ions X cell-1 X min-1, respectively. It is likely that Cr(VI) is transported into RBCs via a physiological anion carrier (""band-3-protein"")."
733752,Pratt and  Myers 1993,Enzymatic reduction of chromium(VI) by human hepatic microsomes,"The reduction of chromium(VI) by human hepatic microsomes was investigated. The reduction rates were proportional to the amount of microsomes added and reduction was mediated by an NADPH-dependent enzymatic system which exhibited a Km for chromate of 1.04 +/- 0.18 microM and a Vmax of 5.03 +/- 0.49 nmol/min/mg protein. Relative to incubation under 0% O2, 21% O2 inhibited microsomal Cr(VI) reduction in three individuals by 53, 36 and 37%. Cr(VI) reduction was not inhibited by metyrapone, carbon monoxide, aminopyrine, piperonyl butoxide or chloroform, suggesting that cytochrome P450s did not play a major role. Thallium trichloride (0.13 and 0.26 mM), a known flavoprotein inhibitor, caused a complete inhibition of both Cr(VI) reduction and NADPH:cytochrome P450 (c) reductase activity. A partial inhibition of Cr(VI) reduction was seen in the presence of n-octylamine, which may suggest a possible role for flavin-containing monooxygenase (FMO). Overall, human microsomal Cr(VI) reduction is very different from the P450-mediated microsomal reduction observed in rodents. Specifically, the human system is much less oxygen-sensitive, has a much greater affinity for chromate and is apparently mediated by flavoproteins.","Enzymatic reduction of chromium(VI) by human hepatic microsomes Abs: The reduction of chromium(VI) by human hepatic microsomes was investigated. The reduction rates were proportional to the amount of microsomes added and reduction was mediated by an NADPH-dependent enzymatic system which exhibited a Km for chromate of 1.04 +/- 0.18 microM and a Vmax of 5.03 +/- 0.49 nmol/min/mg protein. Relative to incubation under 0% O2, 21% O2 inhibited microsomal Cr(VI) reduction in three individuals by 53, 36 and 37%. Cr(VI) reduction was not inhibited by metyrapone, carbon monoxide, aminopyrine, piperonyl butoxide or chloroform, suggesting that cytochrome P450s did not play a major role. Thallium trichloride (0.13 and 0.26 mM), a known flavoprotein inhibitor, caused a complete inhibition of both Cr(VI) reduction and NADPH:cytochrome P450 (c) reductase activity. A partial inhibition of Cr(VI) reduction was seen in the presence of n-octylamine, which may suggest a possible role for flavin-containing monooxygenase (FMO). Overall, human microsomal Cr(VI) reduction is very different from the P450-mediated microsomal reduction observed in rodents. Specifically, the human system is much less oxygen-sensitive, has a much greater affinity for chromate and is apparently mediated by flavoproteins."
733751,O'Flaherty 1996,A physiologically based model of chromium kinetics in the rat,"A physiologically based model of chromium kinetics in rats has been developed. The general structure of the model is similar to that of a model of lead kinetics in rats. Like lead chromium exchanges between plasma and the bone surfaces in contact with plasma, and also like lead, although with much lower efficiency, it can become incorporated into actively mineralizing bone. Both processes are included in the model. Parallel absorption and disposition schemes for chromium(VI) and chromium(III) are linked in the model by reduction processes occurring throughout the body, including the lung and gastrointestinal tract. Examination of a number of data sets from studies in which chromium salts were administered to rats intravenously, orally, or by intratracheal instillation established that intravenous administration, on the one hand, and oral or pulmonary administration, on the other hand, result in different disposition patterns. The model was calibrated based on published oral and intratracheal kinetic studies in rats given soluble chromium(III) and chromium(VI) salts. In the most complete of these studies, chromium concentrations were monitored in individual tissues for 42 days following intratracheal administration of a soluble chromium(VI) salt. Inclusion in the model of a urinary excretion delay was necessary in order to fit excretion data from two other intratracheal studies. Model predictions of blood chromium concentrations are compared with the results of a published kinetic study in which rats were administered a soluble chromium(VI) salt by inhalation.","A physiologically based model of chromium kinetics in the rat Abs: A physiologically based model of chromium kinetics in rats has been developed. The general structure of the model is similar to that of a model of lead kinetics in rats. Like lead chromium exchanges between plasma and the bone surfaces in contact with plasma, and also like lead, although with much lower efficiency, it can become incorporated into actively mineralizing bone. Both processes are included in the model. Parallel absorption and disposition schemes for chromium(VI) and chromium(III) are linked in the model by reduction processes occurring throughout the body, including the lung and gastrointestinal tract. Examination of a number of data sets from studies in which chromium salts were administered to rats intravenously, orally, or by intratracheal instillation established that intravenous administration, on the one hand, and oral or pulmonary administration, on the other hand, result in different disposition patterns. The model was calibrated based on published oral and intratracheal kinetic studies in rats given soluble chromium(III) and chromium(VI) salts. In the most complete of these studies, chromium concentrations were monitored in individual tissues for 42 days following intratracheal administration of a soluble chromium(VI) salt. Inclusion in the model of a urinary excretion delay was necessary in order to fit excretion data from two other intratracheal studies. Model predictions of blood chromium concentrations are compared with the results of a published kinetic study in which rats were administered a soluble chromium(VI) salt by inhalation."
733750,Kuo et al. 1997,Concentration and size distribution of airborne hexavalent chromium in electroplating factories,"Studies have shown that chromium from electroplating factories can cause respiratory problems to workers after prolonged exposure. Since Taiwan has a relatively high number of electroplating factories and minimal data regarding chromium's effect on workers, the authors undertook this study focusing on the size distribution of airborne hexavalent chromium and its concentration levels within the factory. Both area and personal sampling were conducted using a particle fractionating sampler. Samples were analyzed using visible spectrophotometry. A comparison of three types of factories-chromium, nickel-chromium, and zinc-showed that the highest concentrations were found in chromium electroplating factories near the electroplating tank. Hexavalent chromium particles obtained from area sampling had mass median diameters between 1.67-6.38 microns and 0.75-4.73 microns for personal sampling. Particles of this high concentration and small size can enter and cause considerable damage to the respiratory tract.","Concentration and size distribution of airborne hexavalent chromium in electroplating factories Abs: Studies have shown that chromium from electroplating factories can cause respiratory problems to workers after prolonged exposure. Since Taiwan has a relatively high number of electroplating factories and minimal data regarding chromium's effect on workers, the authors undertook this study focusing on the size distribution of airborne hexavalent chromium and its concentration levels within the factory. Both area and personal sampling were conducted using a particle fractionating sampler. Samples were analyzed using visible spectrophotometry. A comparison of three types of factories-chromium, nickel-chromium, and zinc-showed that the highest concentrations were found in chromium electroplating factories near the electroplating tank. Hexavalent chromium particles obtained from area sampling had mass median diameters between 1.67-6.38 microns and 0.75-4.73 microns for personal sampling. Particles of this high concentration and small size can enter and cause considerable damage to the respiratory tract."
733749,De Flora et al. 1997,Estimates of the chromium(VI) reducing capacity in human body compartments as a mechanism for attenuating its potential toxicity and carcinogenicity,"Estimates of the overall reducing capacity of hexavalent chromium(VI) in some human body compartments were made by relating the specific reducing activity of body fluids, cell populations or organs to their average volume, number, or weight. Although these data do not have absolute precision or universal applicability, they provide a rationale for predicting and interpreting the health effects of chromium(VI). The available evidence strongly indicates that chromium(VI) reduction in body fluids and long-lived non-target cells is expected to greatly attenuate its potential toxicity and genotoxicity, to imprint a threshold character to the carcinogenesis process, and to restrict the possible targets of its activity. For example, the chromium(VI) sequestering capacity of whole blood (187-234 mg per individual) and the reducing capacity of red blood cells (at least 93-128 mg) explain why this metal is not a systemic toxicant, except at very high doses, and also explain its lack of carcinogenicity at a distance from the portal of entry into the organism. Reduction by fluids in the digestive tract, e.g. by saliva (0.7-2.1 mg/day) and gastric juice (at least 84-88 mg/day), and sequestration by intestinal bacteria (11-24 mg eliminated daily with feces) account for the poor intestinal absorption of chromium(VI). The chromium(VI) escaping reduction in the digestive tract will be detoxified in the blood of the portal vein system and then in the liver, having an overall reducing capacity of 3300 mg. These processes give reasons for the poor oral toxicity of chromium(VI) and its lack of carcinogenicity when introduced by the oral route or swallowed following reflux from the respiratory tract. In terminal airways chromium(VI) is reduced in the epithelial lining fluid (0.9-1.8 mg) and in pulmonary alveolar macrophages (136 mg). The peripheral lung parenchyma has an overall reducing capacity of 260 mg chromium(VI), with a slightly higher specific activity as compared to the bronchial tree. Therefore, even in the respiratory tract, which is the only consistent target of chromium(VI) carcinogenicity in humans (lung and sinonasal cavities), there are barriers hampering its carcinogenicity. These hurdles could be only overwhelmed under conditions of massive exposure by inhalation, as it occurred in certain work environments prior to the implementation of suitable industrial hygiene measures.","Estimates of the chromium(VI) reducing capacity in human body compartments as a mechanism for attenuating its potential toxicity and carcinogenicity Abs: Estimates of the overall reducing capacity of hexavalent chromium(VI) in some human body compartments were made by relating the specific reducing activity of body fluids, cell populations or organs to their average volume, number, or weight. Although these data do not have absolute precision or universal applicability, they provide a rationale for predicting and interpreting the health effects of chromium(VI). The available evidence strongly indicates that chromium(VI) reduction in body fluids and long-lived non-target cells is expected to greatly attenuate its potential toxicity and genotoxicity, to imprint a threshold character to the carcinogenesis process, and to restrict the possible targets of its activity. For example, the chromium(VI) sequestering capacity of whole blood (187-234 mg per individual) and the reducing capacity of red blood cells (at least 93-128 mg) explain why this metal is not a systemic toxicant, except at very high doses, and also explain its lack of carcinogenicity at a distance from the portal of entry into the organism. Reduction by fluids in the digestive tract, e.g. by saliva (0.7-2.1 mg/day) and gastric juice (at least 84-88 mg/day), and sequestration by intestinal bacteria (11-24 mg eliminated daily with feces) account for the poor intestinal absorption of chromium(VI). The chromium(VI) escaping reduction in the digestive tract will be detoxified in the blood of the portal vein system and then in the liver, having an overall reducing capacity of 3300 mg. These processes give reasons for the poor oral toxicity of chromium(VI) and its lack of carcinogenicity when introduced by the oral route or swallowed following reflux from the respiratory tract. In terminal airways chromium(VI) is reduced in the epithelial lining fluid (0.9-1.8 mg) and in pulmonary alveolar macrophages (136 mg). The peripheral lung parenchyma has an overall reducing capacity of 260 mg chromium(VI), with a slightly higher specific activity as compared to the bronchial tree. Therefore, even in the respiratory tract, which is the only consistent target of chromium(VI) carcinogenicity in humans (lung and sinonasal cavities), there are barriers hampering its carcinogenicity. These hurdles could be only overwhelmed under conditions of massive exposure by inhalation, as it occurred in certain work environments prior to the implementation of suitable industrial hygiene measures."
733748,Corbett et al. 1997,Systemic uptake of chromium in human volunteers following dermal contact with hexavalent chromium (22 mg/L),"This study examined the systemic uptake of chromium in four human volunteers following three hours of contact with water containing hexavalent chromium [Cr(VI)] at a concentration of 22 mg/L. Volunteers were immersed below the shoulders in water at 91 +/- 2.5 degrees F. On the day prior to the experiment and for five days afterwards, samples of urine, plasma, and red blood cells (RBCs) were collected and analyzed for total chromium. Red blood cell chromium concentrations were used as a specific biomarker for systemic uptake of Cr(VI). Although total chromium concentrations in RBCs and plasma increased relative to historical background concentrations on the day of exposure, no sustained elevation of chromium concentrations was observed in RBCs or plasma of the volunteers tested. Since absorption of chromium in the hexavalent state would result in the irreversible binding of Cr(VI) to hemoglobin within the RBC (manifested as a sustained elevation of total chromium concentrations in the RBC), the pattern of blood uptake and urinary excretion observed was consistent with uptake and distribution of chromium in the trivalent state. Small increases were observed in the concentration of total chromium in urine within 48 h of exposure, indicating that some trivalent chromium [Cr(III)] may have penetrated the skin at a rate of about 3.3 x 10(-5) to 4.1 x 10(-4) micrograms/ cm2-h. In short, the data indicated that a 3-h contact with Cr(VI) at concentrations in water plausible for environmental exposure (e.g., swimming) was not expected to result in systemic uptake of measurable amounts of Cr(VI), although a small quantity of Cr(VI) may have penetrated the skin where it was subsequently reduced to Cr(III) prior to systemic uptake.","Systemic uptake of chromium in human volunteers following dermal contact with hexavalent chromium (22 mg/L) Abs: This study examined the systemic uptake of chromium in four human volunteers following three hours of contact with water containing hexavalent chromium [Cr(VI)] at a concentration of 22 mg/L. Volunteers were immersed below the shoulders in water at 91 +/- 2.5 degrees F. On the day prior to the experiment and for five days afterwards, samples of urine, plasma, and red blood cells (RBCs) were collected and analyzed for total chromium. Red blood cell chromium concentrations were used as a specific biomarker for systemic uptake of Cr(VI). Although total chromium concentrations in RBCs and plasma increased relative to historical background concentrations on the day of exposure, no sustained elevation of chromium concentrations was observed in RBCs or plasma of the volunteers tested. Since absorption of chromium in the hexavalent state would result in the irreversible binding of Cr(VI) to hemoglobin within the RBC (manifested as a sustained elevation of total chromium concentrations in the RBC), the pattern of blood uptake and urinary excretion observed was consistent with uptake and distribution of chromium in the trivalent state. Small increases were observed in the concentration of total chromium in urine within 48 h of exposure, indicating that some trivalent chromium [Cr(III)] may have penetrated the skin at a rate of about 3.3 x 10(-5) to 4.1 x 10(-4) micrograms/ cm2-h. In short, the data indicated that a 3-h contact with Cr(VI) at concentrations in water plausible for environmental exposure (e.g., swimming) was not expected to result in systemic uptake of measurable amounts of Cr(VI), although a small quantity of Cr(VI) may have penetrated the skin where it was subsequently reduced to Cr(III) prior to systemic uptake."
733746,Liu et al. 1997,Reduction of carcinogenic chromium(VI) on the skin of living rats,"The reduction of chromate (Cr(VI)) on the skin of living rats was investigated using the technique of in vivo electron paramagnetic resonance (EPR) spectroscopy with a surface coil resonator. Topical application of aqueous solution of Cr(VI) on the skin of rats generated the transient species, Cr(V). Partial removal of the stratum corneum increased the rates of formation and decay of Cr(V), as well as Cr(V) signal intensity. The results demonstrate that skin represents one route for chromium to enter into animals and humans. The generation of reactive Cr(V) species in the reduction of Cr(VI) by the skin may play an important role in the mechanism of Cr(VI)-induced skin cancer. These findings indicate the potential for in vivo EPR spectroscopy for studying the metabolism of paramagnetic reactive species in chemical and biochemical reactions occurring in/on the skin of both small and large animals, and possibly humans.","Reduction of carcinogenic chromium(VI) on the skin of living rats Abs: The reduction of chromate (Cr(VI)) on the skin of living rats was investigated using the technique of in vivo electron paramagnetic resonance (EPR) spectroscopy with a surface coil resonator. Topical application of aqueous solution of Cr(VI) on the skin of rats generated the transient species, Cr(V). Partial removal of the stratum corneum increased the rates of formation and decay of Cr(V), as well as Cr(V) signal intensity. The results demonstrate that skin represents one route for chromium to enter into animals and humans. The generation of reactive Cr(V) species in the reduction of Cr(VI) by the skin may play an important role in the mechanism of Cr(VI)-induced skin cancer. These findings indicate the potential for in vivo EPR spectroscopy for studying the metabolism of paramagnetic reactive species in chemical and biochemical reactions occurring in/on the skin of both small and large animals, and possibly humans."
733745,De Flora 2000,Threshold mechanisms and site specificity in chromium(VI) carcinogenesis,"Ten years have elapsed since the International Agency for Research on Cancer (IARC) evaluated the carcinogenicity of chromium and chromium compounds. Further studies performed during the last decade have provided further epidemiological, experimental and mechanistic data which support the IARC conclusions. A wealth of results indicate that, at variance with chromium(0) and chromium(III), chromium(VI) can induce a variety of genetic and related effects in vitro. The lack of carcinogenicity of chromium(0) and chromium(III) compounds in experimental animals is well established, and only a minority of animal carcinogenicity data with chromium(VI) compounds were positive (30 out of 70, i.e. 42.9%). Moreover, most positive studies used administration routes which do not mimic any human exposure and by-pass physiological defense mechanisms. Typically, positive results were only obtained at implantation sites and at the highest dose tested. Exposure to chromium(VI) has been known for more than a century to be associated with induction of cancer in humans. Carcinogenicity requires massive exposures, as is only encountered in well defined occupational settings, and is site specific, being specifically targeted to the lung and, in some cases, to the sinonasal cavity. Increased death rates for cancers at other sites, which were occasionally reported in some epidemiological studies, were almost invariably not statistically significant, and inconsistent (being counterbalanced by other studies which apparently showed decreased rates for the same cancers). As we recently quantified in human body compartments, chromium(VI) can be reduced in body fluids and non-target cells, which results in its detoxification, due to the poor ability of chromium(III) to cross cell membranes. In target cells, chromium(VI) tends to be metabolized by a network of mechanisms leading to generation of reduced chromium species and reactive oxygen species, which will result either in activation or in detoxification depending on the site of the intracellular reduction and its proximity to DNA. When introduced by the oral route, chromium(VI) is efficiently detoxified upon reduction by saliva and gastric juice, and sequestration by intestinal bacteria. If some chromium(VI) is absorbed by the intestine, it is massively reduced in the blood of the portal system and then in the liver. These mechanisms explain the lack of genotoxicity, carcinogenicity, and induction of other long-term health effects of chromium (VI) by the oral route. Within the respiratory tract, chromium(VI) is reduced in the epithelial-lining fluid, pulmonary alveolar macrophages, bronchial tree and peripheral lung parenchyma cells. Hence, lung cancer can only be induced when chromium(VI) doses overwhelm these defense mechanisms. The efficient uptake and reduction of chromium(VI) in red blood cells explains its lack of carcinogenicity at a distance from the portal of entry into the body. All experimental and epidemiological data, and the underlying mechanisms, point to the occurrence of thresholds in chromium(VI) carcinogenesis.","Threshold mechanisms and site specificity in chromium(VI) carcinogenesis Abs: Ten years have elapsed since the International Agency for Research on Cancer (IARC) evaluated the carcinogenicity of chromium and chromium compounds. Further studies performed during the last decade have provided further epidemiological, experimental and mechanistic data which support the IARC conclusions. A wealth of results indicate that, at variance with chromium(0) and chromium(III), chromium(VI) can induce a variety of genetic and related effects in vitro. The lack of carcinogenicity of chromium(0) and chromium(III) compounds in experimental animals is well established, and only a minority of animal carcinogenicity data with chromium(VI) compounds were positive (30 out of 70, i.e. 42.9%). Moreover, most positive studies used administration routes which do not mimic any human exposure and by-pass physiological defense mechanisms. Typically, positive results were only obtained at implantation sites and at the highest dose tested. Exposure to chromium(VI) has been known for more than a century to be associated with induction of cancer in humans. Carcinogenicity requires massive exposures, as is only encountered in well defined occupational settings, and is site specific, being specifically targeted to the lung and, in some cases, to the sinonasal cavity. Increased death rates for cancers at other sites, which were occasionally reported in some epidemiological studies, were almost invariably not statistically significant, and inconsistent (being counterbalanced by other studies which apparently showed decreased rates for the same cancers). As we recently quantified in human body compartments, chromium(VI) can be reduced in body fluids and non-target cells, which results in its detoxification, due to the poor ability of chromium(III) to cross cell membranes. In target cells, chromium(VI) tends to be metabolized by a network of mechanisms leading to generation of reduced chromium species and reactive oxygen species, which will result either in activation or in detoxification depending on the site of the intracellular reduction and its proximity to DNA. When introduced by the oral route, chromium(VI) is efficiently detoxified upon reduction by saliva and gastric juice, and sequestration by intestinal bacteria. If some chromium(VI) is absorbed by the intestine, it is massively reduced in the blood of the portal system and then in the liver. These mechanisms explain the lack of genotoxicity, carcinogenicity, and induction of other long-term health effects of chromium (VI) by the oral route. Within the respiratory tract, chromium(VI) is reduced in the epithelial-lining fluid, pulmonary alveolar macrophages, bronchial tree and peripheral lung parenchyma cells. Hence, lung cancer can only be induced when chromium(VI) doses overwhelm these defense mechanisms. The efficient uptake and reduction of chromium(VI) in red blood cells explains its lack of carcinogenicity at a distance from the portal of entry into the body. All experimental and epidemiological data, and the underlying mechanisms, point to the occurrence of thresholds in chromium(VI) carcinogenesis."
733744,Matey et al. 2000,Chromic acid burns: Early aggressive excision is the best method to prevent systemic toxicity,"Chromium poisoning can occur from the cutaneous absorption of chromium from burns that are as small as 1% of the total body surface area. In this case report, we describe a patient with 10% total body surface area burns caused by hot chromic acid. The amount of chromium removed by peritoneal dialysis and the amount of chromium in the urine were estimated, as well as the chromium content in the excised skin, serum, and red blood cells. The extent of chromium load from this type of injury and subsequent risk of systemic poisoning is not predictable, and we therefore believe that systemic toxicity is best prevented by early excision of the burned skin.","Chromic acid burns: Early aggressive excision is the best method to prevent systemic toxicity Abs: Chromium poisoning can occur from the cutaneous absorption of chromium from burns that are as small as 1% of the total body surface area. In this case report, we describe a patient with 10% total body surface area burns caused by hot chromic acid. The amount of chromium removed by peritoneal dialysis and the amount of chromium in the urine were estimated, as well as the chromium content in the excised skin, serum, and red blood cells. The extent of chromium load from this type of injury and subsequent risk of systemic poisoning is not predictable, and we therefore believe that systemic toxicity is best prevented by early excision of the burned skin."
733743,Jannetto et al. 2001,Cytochrome b(5) plays a key role in human microsomal chromium(VI) reduction,"The reduction of chromium(VI) to Cr(III) results in the formation of reactive intermediates that contribute to the cytotoxicity, genotoxicity, and carcinogenicity of Cr(VI)-containing compounds. Previous studies suggest that human microsomal Cr(VI) reduction likely proceeds through cytochrome b(5). In order to better understand Cr(VI) toxicity in humans, the role of cytochrome b(5) in combination with P450 reductase was examined in the reductive transformation of Cr(VI). Proteoliposomes containing human recombinant cytochrome b(5) and P450 reductase were constructed. The ability of P450 reductase to mediate efficient electron transfer from NADPH to cytochrome b(5) was confirmed by spectral analysis. The NADPH-dependent Cr(VI) reduction rate mediated by proteoliposomes was then compared to that of human microsomes. When these rates were normalized to equivalent cytochrome b(5) concentrations, the NADPH-dependent Cr(VI) reduction rates mediated by human microsomes were essentially identical to those for proteoliposomes containing cytochrome b(5) plus P450 reductase. Proteoliposomes containing only P450 reductase or cytochrome b(5) exhibited poor Cr(VI) reducing capabilities. Since it had been previously shown that trace amounts of iron (Fe) could dramatically stimulate microsomal Cr(VI) reduction, the ability of Fe to stimulate Cr(VI) reduction by proteoliposomes was examined. Both ferric chloride (FeCl(3)) and ferric adenosine-5'-diphosphate (FeADP) were shown to stimulate Cr(VI) reduction; this stimulation could be abolished by the addition of deferoxamine, a specific Fe(III) chelator. The NADPH-dependent reduction rates of various ferric complexes by proteoliposomes were sufficient to account for the increased Cr(VI) reduction rates seen with the addition of FeCl(3) or FeADP. Cr(V) was detected by electron paramagnetic resonance (EPR) spectroscopy as a transient intermediate formed during NADPH-dependent Cr(VI) reduction mediated by proteoliposomes containing cytochrome b(5) and P450 reductase. Overall, cytochrome b(5) in combination with P450 reductase can account for the majority of the NADPH-dependent Cr(VI) reduction seen with human microsomes.","Cytochrome b(5) plays a key role in human microsomal chromium(VI) reduction Abs: The reduction of chromium(VI) to Cr(III) results in the formation of reactive intermediates that contribute to the cytotoxicity, genotoxicity, and carcinogenicity of Cr(VI)-containing compounds. Previous studies suggest that human microsomal Cr(VI) reduction likely proceeds through cytochrome b(5). In order to better understand Cr(VI) toxicity in humans, the role of cytochrome b(5) in combination with P450 reductase was examined in the reductive transformation of Cr(VI). Proteoliposomes containing human recombinant cytochrome b(5) and P450 reductase were constructed. The ability of P450 reductase to mediate efficient electron transfer from NADPH to cytochrome b(5) was confirmed by spectral analysis. The NADPH-dependent Cr(VI) reduction rate mediated by proteoliposomes was then compared to that of human microsomes. When these rates were normalized to equivalent cytochrome b(5) concentrations, the NADPH-dependent Cr(VI) reduction rates mediated by human microsomes were essentially identical to those for proteoliposomes containing cytochrome b(5) plus P450 reductase. Proteoliposomes containing only P450 reductase or cytochrome b(5) exhibited poor Cr(VI) reducing capabilities. Since it had been previously shown that trace amounts of iron (Fe) could dramatically stimulate microsomal Cr(VI) reduction, the ability of Fe to stimulate Cr(VI) reduction by proteoliposomes was examined. Both ferric chloride (FeCl(3)) and ferric adenosine-5'-diphosphate (FeADP) were shown to stimulate Cr(VI) reduction; this stimulation could be abolished by the addition of deferoxamine, a specific Fe(III) chelator. The NADPH-dependent reduction rates of various ferric complexes by proteoliposomes were sufficient to account for the increased Cr(VI) reduction rates seen with the addition of FeCl(3) or FeADP. Cr(V) was detected by electron paramagnetic resonance (EPR) spectroscopy as a transient intermediate formed during NADPH-dependent Cr(VI) reduction mediated by proteoliposomes containing cytochrome b(5) and P450 reductase. Overall, cytochrome b(5) in combination with P450 reductase can account for the majority of the NADPH-dependent Cr(VI) reduction seen with human microsomes."
733741,Zhitkovich 2005,Importance of chromium-DNA adducts in mutagenicity and toxicity of chromium(VI),,Importance of chromium-DNA adducts in mutagenicity and toxicity of chromium(VI) Abs: 
733740,Van Lierde et al. 2006,In vitro permeation of chromium species through porcine and human skin as determined by capillary electrophoresis-inductively coupled plasma-sector field mass spectrometry,"Since the species that trigger chromium allergy are not yet known, it is important to gain more of an insight into the mechanism of chromium transport through the skin and into the relationship between chromium allergy and chromium species. In vitro permeation studies with porcine and human skin were performed using a Franz static diffusion cell. Investigations attempted to elucidate (i) which Cr compounds are able to permeate through skin, (ii) the influence the Cr concentration in the donor solution has on the Cr permeation, and (iii) the effect that the time of exposure to the donor solution has on Cr permeation. Capillary electrophoresis hyphenated to inductively coupled plasma-sector field mass spectrometry (CE-ICP-SFMS) was used to separate and quantify the Cr species in the receptor fluid. 50 mmol L(-1) phosphate buffer (pH 2.5) was used for CE separation, and two different electrophoretic runs were carried out (in the positive and negative modes). Pneumatic nebulization (PN)-ICP-SFMS was used in order to quantify the total amount of Cr absorbed by the skin after microwave-assisted acid digestion of the tissue. Cr(VI) was found to pass most easily through the skin. Nevertheless, Cr(VI) was also shown to be absorbed more efficiently by the skin than Cr(III), an observation attributed to a more pronounced rejection of the positively charged Cr(III) ions by the skin barrier. These results were in good agreement with in vitro permeation studies previously reported in the literature in which other analytical techniques were used. Differences observed in the permeation of Cr following the application of aqueous Cr donor solutions and Cr-containing simulated sweat donor solutions are also described.","In vitro permeation of chromium species through porcine and human skin as determined by capillary electrophoresis-inductively coupled plasma-sector field mass spectrometry Abs: Since the species that trigger chromium allergy are not yet known, it is important to gain more of an insight into the mechanism of chromium transport through the skin and into the relationship between chromium allergy and chromium species. In vitro permeation studies with porcine and human skin were performed using a Franz static diffusion cell. Investigations attempted to elucidate (i) which Cr compounds are able to permeate through skin, (ii) the influence the Cr concentration in the donor solution has on the Cr permeation, and (iii) the effect that the time of exposure to the donor solution has on Cr permeation. Capillary electrophoresis hyphenated to inductively coupled plasma-sector field mass spectrometry (CE-ICP-SFMS) was used to separate and quantify the Cr species in the receptor fluid. 50 mmol L(-1) phosphate buffer (pH 2.5) was used for CE separation, and two different electrophoretic runs were carried out (in the positive and negative modes). Pneumatic nebulization (PN)-ICP-SFMS was used in order to quantify the total amount of Cr absorbed by the skin after microwave-assisted acid digestion of the tissue. Cr(VI) was found to pass most easily through the skin. Nevertheless, Cr(VI) was also shown to be absorbed more efficiently by the skin than Cr(III), an observation attributed to a more pronounced rejection of the positively charged Cr(III) ions by the skin barrier. These results were in good agreement with in vitro permeation studies previously reported in the literature in which other analytical techniques were used. Differences observed in the permeation of Cr following the application of aqueous Cr donor solutions and Cr-containing simulated sweat donor solutions are also described."
733739,Goldoni et al. 2006,Determination of hexavalent chromium in exhaled breath condensate and environmental air among chrome plating workers,"Chromium speciation has attracted attention because of the different toxicity of Cr(III), which is considered relatively non-toxic, and Cr(VI), which can cross cell membranes mainly as a chromate anion and has been classified as a class I human carcinogen. The aims of the present study were to measure soluble Cr(VI) levels in environmental samples, to develop a simple method of quantifying Cr(VI) in exhaled breath condensate (EBC), and to follow the kinetics of EBC Cr(VI) in chrome plating workers.Personal air samples were collected from 10 chrome platers; EBC was collected from the same workers immediately after the work shift on Tuesday and before the work shift on the following Wednesday. Environmental and EBC Cr(VI) levels were determined by means of colorimetry and electrothermal absorption atomic spectrometry, respectively.The method of detecting Cr(VI) in environmental air was based on the extraction of the Cr(VI)-diphenylcarbazide (Cr(VI)-DPC) complex in 1-butanol, whereas EBC Cr(VI) was determined using a solvent extraction of Cr(VI) as an ion pair with tetrabutylammonium ion, and subsequent direct determination of the complex (Cr(VI)-DPC) in EBC.Kinetic data showed that airborne Cr(VI) was reduced by 50% in airway lining fluid sampled at the end of exposure and that there was a further 50% reduction after about 15 h. The persistence of Cr(VI) in EBC supports the use of EBC in assessing target tissue levels of Cr(VI).","Determination of hexavalent chromium in exhaled breath condensate and environmental air among chrome plating workers Abs: Chromium speciation has attracted attention because of the different toxicity of Cr(III), which is considered relatively non-toxic, and Cr(VI), which can cross cell membranes mainly as a chromate anion and has been classified as a class I human carcinogen. The aims of the present study were to measure soluble Cr(VI) levels in environmental samples, to develop a simple method of quantifying Cr(VI) in exhaled breath condensate (EBC), and to follow the kinetics of EBC Cr(VI) in chrome plating workers.Personal air samples were collected from 10 chrome platers; EBC was collected from the same workers immediately after the work shift on Tuesday and before the work shift on the following Wednesday. Environmental and EBC Cr(VI) levels were determined by means of colorimetry and electrothermal absorption atomic spectrometry, respectively.The method of detecting Cr(VI) in environmental air was based on the extraction of the Cr(VI)-diphenylcarbazide (Cr(VI)-DPC) complex in 1-butanol, whereas EBC Cr(VI) was determined using a solvent extraction of Cr(VI) as an ion pair with tetrabutylammonium ion, and subsequent direct determination of the complex (Cr(VI)-DPC) in EBC.Kinetic data showed that airborne Cr(VI) was reduced by 50% in airway lining fluid sampled at the end of exposure and that there was a further 50% reduction after about 15 h. The persistence of Cr(VI) in EBC supports the use of EBC in assessing target tissue levels of Cr(VI)."
733738,Levina et al. 2007,X-ray absorption and EPR spectroscopic studies of the biotransformations of chromium(VI) in mammalian cells. Is chromodulin an artifact of isolation methods?,"Very different biological activities are usually ascribed to Cr(VI) (a toxin and carcinogen) and Cr(III) (an antidiabetic agent), although recent evidence suggests that both these types of actions are likely to arise from cellular uptake of varying concentrations of Cr(VI). The first systematic study of XANES spectra of Cr(III) complexes formed in Cr(VI)-treated mammalian cells (A549, HepG2, V79, and C2C12 cell lines), and in subcellular fractions of A549 cells, has been performed using a library of XANES spectra of model Cr(III) complexes. The results of multiple linear regression analyses of XANES spectra, in combination with multiple-scattering fits of XAFS spectra, indicate that Cr(III) formed in Cr(VI)-treated cells is most likely to bind to carboxylato, amine, and imidazole residues of amino acids, and to a lesser extent to hydroxo or aqua ligands. A combination of XANES and EPR spectroscopic data for Cr(VI)-treated cells indicates that the main component of Cr(III) formed in such cells is bound to high-molecular-mass ligands (>30 kDa, probably proteins), but significant redistribution of Cr(III) occurs during the cell lysis, which leads to the formation of a low-molecular-mass (<30 kDa) Cr(III)-containing fraction. The spectroscopic (XANES, XAFS, and EPR) properties of this fraction were strikingly similar to those of the purported natural Cr(III)-containing factor, chromodulin, that was reported to be isolated from the reaction of Cr(VI) with liver. These data support the hypothesis that a chromodulin-like species, which is formed from such a reaction, is an artifact of the reported isolation procedure.","X-ray absorption and EPR spectroscopic studies of the biotransformations of chromium(VI) in mammalian cells. Is chromodulin an artifact of isolation methods? Abs: Very different biological activities are usually ascribed to Cr(VI) (a toxin and carcinogen) and Cr(III) (an antidiabetic agent), although recent evidence suggests that both these types of actions are likely to arise from cellular uptake of varying concentrations of Cr(VI). The first systematic study of XANES spectra of Cr(III) complexes formed in Cr(VI)-treated mammalian cells (A549, HepG2, V79, and C2C12 cell lines), and in subcellular fractions of A549 cells, has been performed using a library of XANES spectra of model Cr(III) complexes. The results of multiple linear regression analyses of XANES spectra, in combination with multiple-scattering fits of XAFS spectra, indicate that Cr(III) formed in Cr(VI)-treated cells is most likely to bind to carboxylato, amine, and imidazole residues of amino acids, and to a lesser extent to hydroxo or aqua ligands. A combination of XANES and EPR spectroscopic data for Cr(VI)-treated cells indicates that the main component of Cr(III) formed in such cells is bound to high-molecular-mass ligands (>30 kDa, probably proteins), but significant redistribution of Cr(III) occurs during the cell lysis, which leads to the formation of a low-molecular-mass (<30 kDa) Cr(III)-containing fraction. The spectroscopic (XANES, XAFS, and EPR) properties of this fraction were strikingly similar to those of the purported natural Cr(III)-containing factor, chromodulin, that was reported to be isolated from the reaction of Cr(VI) with liver. These data support the hypothesis that a chromodulin-like species, which is formed from such a reaction, is an artifact of the reported isolation procedure."
733737,Salnikow and  Zhitkovich 2008,"Genetic and epigenetic mechanisms in metal carcinogenesis and cocarcinogenesis: Nickel, arsenic, and chromium","Chronic exposure to nickel(II), chromium(VI), or inorganic arsenic (iAs) has long been known to increase cancer incidence among affected individuals. Recent epidemiological studies have found that carcinogenic risks associated with chromate and iAs exposures were substantially higher than previously thought, which led to major revisions of the federal standards regulating ambient and drinking water levels. Genotoxic effects of Cr(VI) and iAs are strongly influenced by their intracellular metabolism, which creates several reactive intermediates and byproducts. Toxic metals are capable of potent and surprisingly selective activation of stress-signaling pathways, which are known to contribute to the development of human cancers. Depending on the metal, ascorbate (vitamin C) has been found to act either as a strong enhancer or suppressor of toxic responses in human cells. In addition to genetic damage via both oxidative and nonoxidative (DNA adducts) mechanisms, metals can also cause significant changes in DNA methylation and histone modifications, leading to epigenetic silencing or reactivation of gene expression. In vitro genotoxicity experiments and recent animal carcinogenicity studies provided strong support for the idea that metals can act as cocarcinogens in combination with nonmetal carcinogens. Cocarcinogenic and comutagenic effects of metals are likely to stem from their ability to interfere with DNA repair processes. Overall, metal carcinogenesis appears to require the formation of specific metal complexes, chromosomal damage, and activation of signal transduction pathways promoting survival and expansion of genetically/epigenetically altered cells.","Genetic and epigenetic mechanisms in metal carcinogenesis and cocarcinogenesis: Nickel, arsenic, and chromium Abs: Chronic exposure to nickel(II), chromium(VI), or inorganic arsenic (iAs) has long been known to increase cancer incidence among affected individuals. Recent epidemiological studies have found that carcinogenic risks associated with chromate and iAs exposures were substantially higher than previously thought, which led to major revisions of the federal standards regulating ambient and drinking water levels. Genotoxic effects of Cr(VI) and iAs are strongly influenced by their intracellular metabolism, which creates several reactive intermediates and byproducts. Toxic metals are capable of potent and surprisingly selective activation of stress-signaling pathways, which are known to contribute to the development of human cancers. Depending on the metal, ascorbate (vitamin C) has been found to act either as a strong enhancer or suppressor of toxic responses in human cells. In addition to genetic damage via both oxidative and nonoxidative (DNA adducts) mechanisms, metals can also cause significant changes in DNA methylation and histone modifications, leading to epigenetic silencing or reactivation of gene expression. In vitro genotoxicity experiments and recent animal carcinogenicity studies provided strong support for the idea that metals can act as cocarcinogens in combination with nonmetal carcinogens. Cocarcinogenic and comutagenic effects of metals are likely to stem from their ability to interfere with DNA repair processes. Overall, metal carcinogenesis appears to require the formation of specific metal complexes, chromosomal damage, and activation of signal transduction pathways promoting survival and expansion of genetically/epigenetically altered cells."
733736,Borthiry et al. 2008,Reductive activation of hexavalent chromium by human lung epithelial cells: Generation of Cr(V) and Cr(V)-thiol species,"Chromium(VI) compounds (e.g. chromates) are cytotoxic, mutagenic, and potentially carcinogenic. The reduction of Cr(VI) can yield reactive intermediates such as Cr(V) and reactive oxygen species. Bronchial epithelial cells are the primary site of pulmonary exposure to inhaled Cr(VI) and are the primary cells from which Cr(VI)-associated human cancers arise. BEAS-2B cells were used here as a model of normal human bronchial epithelium for studies on the reductive activation of Cr(VI). Cells incubated with Na(2)CrO(4) exhibited two Cr(V) ESR signals, g=1.979 and 1.985, which persisted for at least 1h. The g=1.979 signal is similar to that generated in vitro by human microsomes and by proteoliposomes containing P450 reductase and cytochrome b(5). Unlike many cells in culture, these cells continued to express P450 reductase and cytochrome b(5). Studies with the non-selective thiol oxidant diamide indicated that the g=1.985 signal was thiol-dependent whereas the g=1.979 signal was not. Pretreatment with phenazine methosulfate eliminated both Cr(V) signals suggesting that Cr(V) generation is largely NAD(P)H-dependent. ESR spectra indicated that a portion of the Cr(VI) was rapidly reduced to Cr(III). Cells incubated with an insoluble chromate, ZnCrO(4), also generated both Cr(V) signals, whereas Cr(V) was not detected with insoluble PbCrO(4). In clonogenic assays, the cells were very sensitive to Na(2)CrO(4) and ZnCrO(4), but considerably less sensitive to PbCrO(4).","Reductive activation of hexavalent chromium by human lung epithelial cells: Generation of Cr(V) and Cr(V)-thiol species Abs: Chromium(VI) compounds (e.g. chromates) are cytotoxic, mutagenic, and potentially carcinogenic. The reduction of Cr(VI) can yield reactive intermediates such as Cr(V) and reactive oxygen species. Bronchial epithelial cells are the primary site of pulmonary exposure to inhaled Cr(VI) and are the primary cells from which Cr(VI)-associated human cancers arise. BEAS-2B cells were used here as a model of normal human bronchial epithelium for studies on the reductive activation of Cr(VI). Cells incubated with Na(2)CrO(4) exhibited two Cr(V) ESR signals, g=1.979 and 1.985, which persisted for at least 1h. The g=1.979 signal is similar to that generated in vitro by human microsomes and by proteoliposomes containing P450 reductase and cytochrome b(5). Unlike many cells in culture, these cells continued to express P450 reductase and cytochrome b(5). Studies with the non-selective thiol oxidant diamide indicated that the g=1.985 signal was thiol-dependent whereas the g=1.979 signal was not. Pretreatment with phenazine methosulfate eliminated both Cr(V) signals suggesting that Cr(V) generation is largely NAD(P)H-dependent. ESR spectra indicated that a portion of the Cr(VI) was rapidly reduced to Cr(III). Cells incubated with an insoluble chromate, ZnCrO(4), also generated both Cr(V) signals, whereas Cr(V) was not detected with insoluble PbCrO(4). In clonogenic assays, the cells were very sensitive to Na(2)CrO(4) and ZnCrO(4), but considerably less sensitive to PbCrO(4)."
733735,Goldoni et al. 2010,"Chromium in exhaled breath condensate (EBC), erythrocytes, plasma and urine in the biomonitoring of chrome-plating workers exposed to soluble Cr(VI)","Chromium (Cr) levels measured in exhaled breath condensate (EBC-Cr) and urine (Cr-U) at the beginning and end of working shifts were related to those measured in erythrocytes (Cr-RBC) and plasma in 14 non-smoking male chrome-plating workers exposed to Cr(VI) in soluble aerosol form who did not report any significant current or past respiratory disease. Cr-U mainly correlated with Cr-P (Cr in plasma) at the end of the working shift (r(2) = 0.59, p < 0.01), whereas Cr-RBC correlated with EBC-Cr (r(2) = 0.32, p < 0.05); at the beginning of the shift, the only significant correlation was between Cr-U and Cr-RBC (r(2) = 0.74, p < 0.01). The clearance of Cr(iii) arising from Cr(VI) reduction was rapid, thus making Cr-U and Cr-P ideal biomarkers of the most recent exposure, whereas Cr-RBC may represent the fraction of Cr(VI) that reaches the bloodstream in non-reduced form and therefore depends on the airway inhaled dose represented by EBC-Cr. Cr-RBC clearance is slower and not only involves the free diffusion of Cr(iii) from RBC to plasma, but probably also involves more complicated kinetic phenomena involving other tissues and organs, which may explain the correlation between Cr-RBC and Cr-U and the lack of correlation Cr-RBC and Cr-P at least 36 h after the last exposure. In conclusion, our findings reinforce the idea that measuring Cr in EBC can significantly contribute to traditional biomonitoring by providing specific information at the target organ level and integrating our knowledge of Cr toxicokinetics.","Chromium in exhaled breath condensate (EBC), erythrocytes, plasma and urine in the biomonitoring of chrome-plating workers exposed to soluble Cr(VI) Abs: Chromium (Cr) levels measured in exhaled breath condensate (EBC-Cr) and urine (Cr-U) at the beginning and end of working shifts were related to those measured in erythrocytes (Cr-RBC) and plasma in 14 non-smoking male chrome-plating workers exposed to Cr(VI) in soluble aerosol form who did not report any significant current or past respiratory disease. Cr-U mainly correlated with Cr-P (Cr in plasma) at the end of the working shift (r(2) = 0.59, p < 0.01), whereas Cr-RBC correlated with EBC-Cr (r(2) = 0.32, p < 0.05); at the beginning of the shift, the only significant correlation was between Cr-U and Cr-RBC (r(2) = 0.74, p < 0.01). The clearance of Cr(iii) arising from Cr(VI) reduction was rapid, thus making Cr-U and Cr-P ideal biomarkers of the most recent exposure, whereas Cr-RBC may represent the fraction of Cr(VI) that reaches the bloodstream in non-reduced form and therefore depends on the airway inhaled dose represented by EBC-Cr. Cr-RBC clearance is slower and not only involves the free diffusion of Cr(iii) from RBC to plasma, but probably also involves more complicated kinetic phenomena involving other tissues and organs, which may explain the correlation between Cr-RBC and Cr-U and the lack of correlation Cr-RBC and Cr-P at least 36 h after the last exposure. In conclusion, our findings reinforce the idea that measuring Cr in EBC can significantly contribute to traditional biomonitoring by providing specific information at the target organ level and integrating our knowledge of Cr toxicokinetics."
733433,Vreeburg et al. 1991,Successful induction of allergic contact dermatitis to mercury and chromium in mice,"Availability of reproducible mouse models for allergic contact dermatitis (ACD) to the metal allergens nickel, mercury and chromium, would be of great value for pathogenetic and preventive studies. We explored epicutaneous sensitization to nickel, mercury and chromium in mice in which oral grooming of the sensitization site was prevented by a plaster cast around the abdomen and lower thorax. This procedure was based on earlier findings that oral ingestion of allergen could prevent contact sensitization. The present results show that BALB/c mice can be readily sensitized to mercury and chromium using this epicutaneous casting method, without the further use of adjuvants. With nickel, however, neither this method, nor conventional methods involving the use of Freund's complete adjuvant (FCA) were effective.","Successful induction of allergic contact dermatitis to mercury and chromium in mice Abs: Availability of reproducible mouse models for allergic contact dermatitis (ACD) to the metal allergens nickel, mercury and chromium, would be of great value for pathogenetic and preventive studies. We explored epicutaneous sensitization to nickel, mercury and chromium in mice in which oral grooming of the sensitization site was prevented by a plaster cast around the abdomen and lower thorax. This procedure was based on earlier findings that oral ingestion of allergen could prevent contact sensitization. The present results show that BALB/c mice can be readily sensitized to mercury and chromium using this epicutaneous casting method, without the further use of adjuvants. With nickel, however, neither this method, nor conventional methods involving the use of Freund's complete adjuvant (FCA) were effective."
733432,Mor et al. 1988,Successful contact sensitization to chromate in mice,"Mice of the randomly bred strain ICR and of the inbred strain BALB/c could be successfully sensitized to chromate by repeated topical applications of a solution of potassium bichromate in dimethyl sulfoxide. The specificity of chromium sensitization was ascertained by ear tests, specific desensitization by intravenous injection of potassium bichromate and by histological ear sections showing marked infiltrates of leukocytes following ear application of chromium-dimethyl sulfoxide in already sensitized animals. It is concluded that mice may provide a useful experimental model for study of contact sensitivity to chromium.","Successful contact sensitization to chromate in mice Abs: Mice of the randomly bred strain ICR and of the inbred strain BALB/c could be successfully sensitized to chromate by repeated topical applications of a solution of potassium bichromate in dimethyl sulfoxide. The specificity of chromium sensitization was ascertained by ear tests, specific desensitization by intravenous injection of potassium bichromate and by histological ear sections showing marked infiltrates of leukocytes following ear application of chromium-dimethyl sulfoxide in already sensitized animals. It is concluded that mice may provide a useful experimental model for study of contact sensitivity to chromium."
733431,Kimber et al. 1990,Contact sensitization of mice to nickel sulphate and potassium dichromate,"The ability of nickel sulphate and potassium dichromate to induce contact sensitization in mice has been investigated. Topical exposure of mice to 0.5% potassium dichromate in dimethylsulphoxide (DMSO) under occlusion resulted in specific contact sensitization in each of 7 experiments. Although sensitization to nickel sulphate under the same conditions was weak and somewhat variable, evidence for significant levels of contact allergy was obtained in 4 of 7 experiments. In addition, repeated topical application of both nickel sulphate and potassium dichromate in DMSO was found to result in the induction of lymphocyte proliferative responses in lymph nodes draining the site of exposure. These data indicate that epicutaneous exposure to both metal salts may cause specific contact sensitization in mice.","Contact sensitization of mice to nickel sulphate and potassium dichromate Abs: The ability of nickel sulphate and potassium dichromate to induce contact sensitization in mice has been investigated. Topical exposure of mice to 0.5% potassium dichromate in dimethylsulphoxide (DMSO) under occlusion resulted in specific contact sensitization in each of 7 experiments. Although sensitization to nickel sulphate under the same conditions was weak and somewhat variable, evidence for significant levels of contact allergy was obtained in 4 of 7 experiments. In addition, repeated topical application of both nickel sulphate and potassium dichromate in DMSO was found to result in the induction of lymphocyte proliferative responses in lymph nodes draining the site of exposure. These data indicate that epicutaneous exposure to both metal salts may cause specific contact sensitization in mice."
732752,Sauvant et al. 1999,Tetrahymena pyriformis: a tool for toxicological studies. A review,"Among protozoa, Tetrahymena pyriformis is the most commonly ciliated model used for laboratory research. After a brief description of the morphology and biology of Tetrahymena pyriformis, this article focuses on the most important and recent investigations performed with this species in toxicology and ecotoxicology. The methodological features of its culture, and main tests, based on cell growth rate, biochemical markers, behavioral changes and motility, are discussed. Examples of xenobiotics (organic and inorganic substances, pharmaceutical drugs, water pollutants) tested with Tetrahymena pyriformis are also given.","Tetrahymena pyriformis: a tool for toxicological studies. A review Abs: Among protozoa, Tetrahymena pyriformis is the most commonly ciliated model used for laboratory research. After a brief description of the morphology and biology of Tetrahymena pyriformis, this article focuses on the most important and recent investigations performed with this species in toxicology and ecotoxicology. The methodological features of its culture, and main tests, based on cell growth rate, biochemical markers, behavioral changes and motility, are discussed. Examples of xenobiotics (organic and inorganic substances, pharmaceutical drugs, water pollutants) tested with Tetrahymena pyriformis are also given."
732578,Aiyar et al. 1989,"Role of chromium(V), glutathione thiyl radical and hydroxyl radical intermediates in Chromium(VI)-induced DNA Damage","In vitro chromium(VI) is unreactive toward DNA under physiological conditions. Therefore, the ability of chromium(VI) to damage DNA depends on the presence of cellular components capable of forming “reactive intermediates”; upon reaction with chromium(VI). We have examined the role of glutathione and hydrogen peroxide in chromium(VI)-induced DNA damage in vitro. Reaction of glutathione with chromium(VI) produced significant levels of two chromium(V) complexes and glutathione thiyl radical, whereas reaction of chromium(VI) with hydrogen peroxide produced hydroxyl radical without producing detectable levels of chromium(V). Reaction of DNA with chromium(VI) in the presence of glutathione resulted in Cr-DNA adducts with little DNA strand breakage. Reaction of DNA with chromium(Vl) in the presence of hydrogen peroxide produced the 8-hydroxydeoxyguanosine adduct and extensive DNA strand breakage in the absence of significant Cr-DNA adduct formation. These results suggest that the nature of chromium(VI)-induced DNA damage will be strongly dependent on the reactive intermediates, i.e. chromium(V) complexes, glutathione thiyl radical and hydroxyl radical, produced by cellular components and systems active in chromium(VI) metabolism.","Role of chromium(V), glutathione thiyl radical and hydroxyl radical intermediates in Chromium(VI)-induced DNA Damage Abs: In vitro chromium(VI) is unreactive toward DNA under physiological conditions. Therefore, the ability of chromium(VI) to damage DNA depends on the presence of cellular components capable of forming “reactive intermediates”; upon reaction with chromium(VI). We have examined the role of glutathione and hydrogen peroxide in chromium(VI)-induced DNA damage in vitro. Reaction of glutathione with chromium(VI) produced significant levels of two chromium(V) complexes and glutathione thiyl radical, whereas reaction of chromium(VI) with hydrogen peroxide produced hydroxyl radical without producing detectable levels of chromium(V). Reaction of DNA with chromium(VI) in the presence of glutathione resulted in Cr-DNA adducts with little DNA strand breakage. Reaction of DNA with chromium(Vl) in the presence of hydrogen peroxide produced the 8-hydroxydeoxyguanosine adduct and extensive DNA strand breakage in the absence of significant Cr-DNA adduct formation. These results suggest that the nature of chromium(VI)-induced DNA damage will be strongly dependent on the reactive intermediates, i.e. chromium(V) complexes, glutathione thiyl radical and hydroxyl radical, produced by cellular components and systems active in chromium(VI) metabolism."
732572,Perrault et al. 1995,Physico-chemical fate of chromium compounds in the sheep lung model,"Transmission electron microscopy (TEM) equipped with energy-dispersive x-ray analysis (EDX), electron spectroscopy for chemical analysis (ESCA), secondary ion mass spectrometry (SIMS), and laser microprobe for mass analysis (LAMMA) were used to follow the fate of chromium compounds deposited in the sheep tracheal lobe. Four chromium compounds were used: two chromium(VI) compounds (lead chromate and chromium trioxide) and two chromium(III) compounds (chronic oxide and chromium sulfate). Chromium trioxide is very soluble and the other three are slightly soluble. The compositions, concentrations, and sizes of particles were determined in the bronchoalveolar lavages (BAL) at d 2, 3, 5, and 30 after instillation and on the lung samples collected at d 31. The concentrations of particles in the BAL samples separated the chromium compounds in two groups where Cr2O3 and PbCrO4 (as Pb) were higher than Cr2(SO4)3, PbCrO4 (as Cr), and CrO3. The half-life for alveolar clearance of Cr2O3 and Cr2(SO4)3 has been calculated respectively at 11 and 80 d. Prismatic PbCrO4 particles break up in the lung and sustain a high concentration of isometric particles of lead chromate and another lead-containing compound in the BAL. The CrO3 instilled particles react with endogenous compounds or are transformed to insoluble hydroxyl complexes instead of diffusing very rapidly through the alveolar-capillary barrier. The alveolar clearance as measured in the BAL is not different from the control.","Physico-chemical fate of chromium compounds in the sheep lung model Abs: Transmission electron microscopy (TEM) equipped with energy-dispersive x-ray analysis (EDX), electron spectroscopy for chemical analysis (ESCA), secondary ion mass spectrometry (SIMS), and laser microprobe for mass analysis (LAMMA) were used to follow the fate of chromium compounds deposited in the sheep tracheal lobe. Four chromium compounds were used: two chromium(VI) compounds (lead chromate and chromium trioxide) and two chromium(III) compounds (chronic oxide and chromium sulfate). Chromium trioxide is very soluble and the other three are slightly soluble. The compositions, concentrations, and sizes of particles were determined in the bronchoalveolar lavages (BAL) at d 2, 3, 5, and 30 after instillation and on the lung samples collected at d 31. The concentrations of particles in the BAL samples separated the chromium compounds in two groups where Cr2O3 and PbCrO4 (as Pb) were higher than Cr2(SO4)3, PbCrO4 (as Cr), and CrO3. The half-life for alveolar clearance of Cr2O3 and Cr2(SO4)3 has been calculated respectively at 11 and 80 d. Prismatic PbCrO4 particles break up in the lung and sustain a high concentration of isometric particles of lead chromate and another lead-containing compound in the BAL. The CrO3 instilled particles react with endogenous compounds or are transformed to insoluble hydroxyl complexes instead of diffusing very rapidly through the alveolar-capillary barrier. The alveolar clearance as measured in the BAL is not different from the control."
732571,Myers and  Myers 1998,Iron stimulates the rate of reduction of hexavalent chromium by human microsomes,"The NADPH-dependent reduction of chromium (VI), a known carcinogen, by hepatic microsomes was very similar for all five humans examined, with an apparent Km for chromate of 1.04-1.68 microM, and a Vmax of 10.4-10.7 nmol/min/mg protein. Inhibitor studies indicate no role for cytochrome P450s, but a prominent role for flavoproteins, which could include P450 reductase, flavin-containing mono-oxygenase and cytochrome b5. Relative to anaerobic conditions, Cr(VI) reduction was inhibited only 26-37% by room air, which indicates that human microsomal Cr(VI) reduction could still proceed at significant rates, even in tissues with high O2 tensions. Studies with lung microsomes from one human exhibited Vmax and Km values that were two-thirds lower and 2.8-fold greater, respectively, than those of hepatic microsomes from the same individual; other Cr(VI)-reducing parameters were similar for lung and liver. Various forms of exogenous iron, when present at 0.76-6.3 microM, markedly enhanced both liver and lung microsomal rates and Vmax of Cr(VI) reduction, but did not significantly alter the other Cr(VI)-reducing parameters (Km, effects of O2 and inhibitors). These iron levels were 3.1- to 26-fold lower than the initial Cr(VI) concentration, which suggests that iron is serving a catalytic role. The ratio of human microsomal Cr(VI) reduction rates under aerobic versus anaerobic conditions remained fairly constant, regardless of iron concentration. Small increases in intracellular iron could therefore lead to large increases in the rate and extent of microsomal Cr(VI) reduction. Individuals that are simultaneously exposed to Cr(VI) and to agents that increase intracellular iron could therefore be at potentially greater risk for Cr(VI) toxicity and carcinogenicity.","Iron stimulates the rate of reduction of hexavalent chromium by human microsomes Abs: The NADPH-dependent reduction of chromium (VI), a known carcinogen, by hepatic microsomes was very similar for all five humans examined, with an apparent Km for chromate of 1.04-1.68 microM, and a Vmax of 10.4-10.7 nmol/min/mg protein. Inhibitor studies indicate no role for cytochrome P450s, but a prominent role for flavoproteins, which could include P450 reductase, flavin-containing mono-oxygenase and cytochrome b5. Relative to anaerobic conditions, Cr(VI) reduction was inhibited only 26-37% by room air, which indicates that human microsomal Cr(VI) reduction could still proceed at significant rates, even in tissues with high O2 tensions. Studies with lung microsomes from one human exhibited Vmax and Km values that were two-thirds lower and 2.8-fold greater, respectively, than those of hepatic microsomes from the same individual; other Cr(VI)-reducing parameters were similar for lung and liver. Various forms of exogenous iron, when present at 0.76-6.3 microM, markedly enhanced both liver and lung microsomal rates and Vmax of Cr(VI) reduction, but did not significantly alter the other Cr(VI)-reducing parameters (Km, effects of O2 and inhibitors). These iron levels were 3.1- to 26-fold lower than the initial Cr(VI) concentration, which suggests that iron is serving a catalytic role. The ratio of human microsomal Cr(VI) reduction rates under aerobic versus anaerobic conditions remained fairly constant, regardless of iron concentration. Small increases in intracellular iron could therefore lead to large increases in the rate and extent of microsomal Cr(VI) reduction. Individuals that are simultaneously exposed to Cr(VI) and to agents that increase intracellular iron could therefore be at potentially greater risk for Cr(VI) toxicity and carcinogenicity."
732570,Mancuso 1997,Chromium as an industrial carcinogen: Part II. Chromium in human tissues,"A continuation of the findings in a study of workers hired in 1931-1937 in a chromate plant, directed at the evaluation of the carcinogenic risk of insoluble, soluble, and total chromium. Chemical analyses of tissues of autopsies, identified by age at hire, cumulative exposure to insoluble, soluble, and total chromium and interval since last exposure are cited for three lung cancer cases. Histological identification of insoluble chromium was demonstrated. Marked deposition and retention of concentrations of chromium was noted 18.0 years since last exposure. In one case with cumulative exposure to insoluble chromium of 10.74 mg versus 0.63 mg for soluble chromium and histological demonstration of insoluble chromium, chrysotile was also identified.","Chromium as an industrial carcinogen: Part II. Chromium in human tissues Abs: A continuation of the findings in a study of workers hired in 1931-1937 in a chromate plant, directed at the evaluation of the carcinogenic risk of insoluble, soluble, and total chromium. Chemical analyses of tissues of autopsies, identified by age at hire, cumulative exposure to insoluble, soluble, and total chromium and interval since last exposure are cited for three lung cancer cases. Histological identification of insoluble chromium was demonstrated. Marked deposition and retention of concentrations of chromium was noted 18.0 years since last exposure. In one case with cumulative exposure to insoluble chromium of 10.74 mg versus 0.63 mg for soluble chromium and histological demonstration of insoluble chromium, chrysotile was also identified."
732568,Kiilunen 1997,Occupational exposure to chromium and nickel in the 1980s in Finland,"Two large data bases accumulated from the 1980s at the Finnish Institute of Occupational Health, one with results on urinary chromium and nickel analyses and the other with results on total and hexavalent chromium and nickel, were compiled and analysed in order to clarify the occupational exposure during the 1980s, and to reveal possible trends in the exposure of workers in different jobs. The data were processed in three batches: years 1980-1982, 1983-1985 and 1986-1989. The median values of urinary chromium exceeded the biomonitoring action level, BAL, in metal workers, and the mean values exceeded the BAL in both metal workers and plasma cutters. Among all worker groups the median values of urinary chromium remained quite stable during the study period. The median values of urinary nickel concentration did not exceed the BAL in any worker group studied, but an increasing trend was observed among moulders. In the breathing zone of grinders, the median value of total or trivalent chromium exceeded the occupational exposure limit, OEL. The medial of hexavalent chromium concentration in the breathing zone of metal sprayers and spray painters was higher than the OEL. No decreasing trend in exposure could be observed during the 10-year period in breathing zone air.","Occupational exposure to chromium and nickel in the 1980s in Finland Abs: Two large data bases accumulated from the 1980s at the Finnish Institute of Occupational Health, one with results on urinary chromium and nickel analyses and the other with results on total and hexavalent chromium and nickel, were compiled and analysed in order to clarify the occupational exposure during the 1980s, and to reveal possible trends in the exposure of workers in different jobs. The data were processed in three batches: years 1980-1982, 1983-1985 and 1986-1989. The median values of urinary chromium exceeded the biomonitoring action level, BAL, in metal workers, and the mean values exceeded the BAL in both metal workers and plasma cutters. Among all worker groups the median values of urinary chromium remained quite stable during the study period. The median values of urinary nickel concentration did not exceed the BAL in any worker group studied, but an increasing trend was observed among moulders. In the breathing zone of grinders, the median value of total or trivalent chromium exceeded the occupational exposure limit, OEL. The medial of hexavalent chromium concentration in the breathing zone of metal sprayers and spray painters was higher than the OEL. No decreasing trend in exposure could be observed during the 10-year period in breathing zone air."
732562,Corbett et al. 1998,In vitro reduction kinetics of hexavalent chromium in human blood,"This study examines time- and concentration-dependent changes in distribution of hexavalent chromium [Cr(VI)] and total chromium [Cr-(TOT)] in reconstituted human blood following addition of potassium dichromate. Fresh human blood stabilized with EDTA was obtained from human volunteers soon after meal ingestion and at 2.5 h after a light meal (herein defined as &quot;2.5-h fasted&quot; conditions). Cr(VI) spiked into plasma under 2.5-h fasting conditions at 3.0-12.5 micrograms/L was stable for several hours, indicating a lack of appreciable reductive capacity in isolated plasma. Spiked plasma following a recent meal exhibited immediate but variable reduction of Cr(VI) up to 300 micrograms/L. When the spiked plasma was recombined with the red blood cell (RBC) fraction, rapid reduction occurred in both the plasma and the RBC fractions based on measurement of Cr(VI) and Cr(TOT). The data indicate that plasma reduction capacity is enhanced by a recent meal, but may be overwhelmed at Cr(VI) concentrations between 2000 and 10,000 micrograms/L. These data also suggest that the RBC fraction apparently has the capacity to reduce Cr(VI) at concentrations in blood up to 15,000 micrograms/L, and that the rate of Cr(VI) uptake into RBCs may not exceed the rate of intracellular reduction at these concentrations.","In vitro reduction kinetics of hexavalent chromium in human blood Abs: This study examines time- and concentration-dependent changes in distribution of hexavalent chromium [Cr(VI)] and total chromium [Cr-(TOT)] in reconstituted human blood following addition of potassium dichromate. Fresh human blood stabilized with EDTA was obtained from human volunteers soon after meal ingestion and at 2.5 h after a light meal (herein defined as &quot;2.5-h fasted&quot; conditions). Cr(VI) spiked into plasma under 2.5-h fasting conditions at 3.0-12.5 micrograms/L was stable for several hours, indicating a lack of appreciable reductive capacity in isolated plasma. Spiked plasma following a recent meal exhibited immediate but variable reduction of Cr(VI) up to 300 micrograms/L. When the spiked plasma was recombined with the red blood cell (RBC) fraction, rapid reduction occurred in both the plasma and the RBC fractions based on measurement of Cr(VI) and Cr(TOT). The data indicate that plasma reduction capacity is enhanced by a recent meal, but may be overwhelmed at Cr(VI) concentrations between 2000 and 10,000 micrograms/L. These data also suggest that the RBC fraction apparently has the capacity to reduce Cr(VI) at concentrations in blood up to 15,000 micrograms/L, and that the rate of Cr(VI) uptake into RBCs may not exceed the rate of intracellular reduction at these concentrations."
732558,Aiyar et al. 1991,Reaction of chromium(VI) with glutathione or with hydrogen peroxide: identification of reactive intermediates and their role in chromium(VI)-induced DNA damage,"The types of reactive intermediates generated upon reduction of chromium(VI) by glutathione or hydrogen peroxide and the resulting DNA damage have been determined. In vitro, reaction of chromium(VI) with glutathione led to formation of two chromium(V) complexes and the glutathione thiyl radical. When chromium(VI) was reacted with DNA in the presence of glutathione, chromium-DNA adducts were obtained, with no DNA strand breakage. The level of chromium-DNA adduct formation correlated with chromium(V) formation. Reaction of chromium(VI) with hydrogen peroxide led to formation of hydroxyl radical. No chromium(V) was detectable at 24 degrees C (297 K); however, low levels of the tetraperoxochromium(V) complex were detected at 77 K. Reaction of chromium(VI) with DNA in the presence of hydrogen peroxide produced significant DNA strand breakage and the 8-hydroxydeoxyguanosine adduct, whose formation correlated with hydroxyl radical production. No significant chromium-DNA adduct formation was detected. Thus, the nature of chromium(VI)-induced DNA damage appears to be dependent on the reactive intermediates, i.e. chromium(V) or hydroxyl radical, produced during the reduction of chromium(VI).","Reaction of chromium(VI) with glutathione or with hydrogen peroxide: identification of reactive intermediates and their role in chromium(VI)-induced DNA damage Abs: The types of reactive intermediates generated upon reduction of chromium(VI) by glutathione or hydrogen peroxide and the resulting DNA damage have been determined. In vitro, reaction of chromium(VI) with glutathione led to formation of two chromium(V) complexes and the glutathione thiyl radical. When chromium(VI) was reacted with DNA in the presence of glutathione, chromium-DNA adducts were obtained, with no DNA strand breakage. The level of chromium-DNA adduct formation correlated with chromium(V) formation. Reaction of chromium(VI) with hydrogen peroxide led to formation of hydroxyl radical. No chromium(V) was detectable at 24 degrees C (297 K); however, low levels of the tetraperoxochromium(V) complex were detected at 77 K. Reaction of chromium(VI) with DNA in the presence of hydrogen peroxide produced significant DNA strand breakage and the 8-hydroxydeoxyguanosine adduct, whose formation correlated with hydroxyl radical production. No significant chromium-DNA adduct formation was detected. Thus, the nature of chromium(VI)-induced DNA damage appears to be dependent on the reactive intermediates, i.e. chromium(V) or hydroxyl radical, produced during the reduction of chromium(VI)."
730669,Derelanko et al. 1999,"Thirteen-week subchronic rat inhalation toxicity study with a recovery phase of trivalent chromium compounds, chromic oxide, and basic chromium sulfate","The toxicity of trivalent chromium compounds; chromic oxide and basic chromium sulfate, was investigated in rats in a 13-week nose-only inhalation study that included a 13-week recovery period. Nose-only exposures to insoluble chromic oxide dust at 4.4, 15, or 44 mg/m3 or soluble basic chromium sulfate dust at 17, 54, or 168 mg/m3 (trivalent chromium equivalent concentrations of 3, 10, and 30 mg/m3) were carried out for 6 h/day, 5 days/week. No compound-related mortality occurred. General toxic effects, only observed with high-exposure levels of basic chromium sulfate, included sporadic signs of labored breathing and depressed body weights. No apparent compound-related effects were noted for sperm motility or morphology, for any concentration of either test material. Bronchoalveolar lavage fluid evaluations showed test material in mononuclear cells with chromic oxide and increased neutrophils, protein, lactic dehydrogenase and cellular debris with basic chromium sulfate. The principle effects for both materials were primarily to the respiratory tract. Chromic oxide caused pathological changes in the bronchial and mediastinal lymphatic tissue and lungs, consisting of the presence of pigment-laden macrophages, lymphoid and septal hyperplasia, and interstitial inflammation similar to that observed with other inert dusts. Basic chromium sulfate produced more severe and widespread effects in the nasal cavity, larynx, lungs, and mediastinal lymph node. Effects were characterized by accumulation of foreign material, infiltration of alveolar macrophages, septal cell hyperplasia, and granulomatous and chronic inflammation. Pigment was still present in chromic oxide and, to a lesser extent, in basic chromium sulfate-treated animals after the 13-week recovery period, with partial recovery of the pathological lesions. A NOAEL was not established for either test material, but 4.4 mg/m3 was thought to be near the NOAEL level for subchronic exposure to chromic oxide. The results of this study indicate significant differences in toxicity to the respiratory tract between trivalent chromium compounds chromic oxide and basic chromium sulfate. These are likely related to differences in acidity and water solubility, rather than chromium concentration per se. This conclusion is substantiated by the lack of effect on other internal organs.","Thirteen-week subchronic rat inhalation toxicity study with a recovery phase of trivalent chromium compounds, chromic oxide, and basic chromium sulfate Abs: The toxicity of trivalent chromium compounds; chromic oxide and basic chromium sulfate, was investigated in rats in a 13-week nose-only inhalation study that included a 13-week recovery period. Nose-only exposures to insoluble chromic oxide dust at 4.4, 15, or 44 mg/m3 or soluble basic chromium sulfate dust at 17, 54, or 168 mg/m3 (trivalent chromium equivalent concentrations of 3, 10, and 30 mg/m3) were carried out for 6 h/day, 5 days/week. No compound-related mortality occurred. General toxic effects, only observed with high-exposure levels of basic chromium sulfate, included sporadic signs of labored breathing and depressed body weights. No apparent compound-related effects were noted for sperm motility or morphology, for any concentration of either test material. Bronchoalveolar lavage fluid evaluations showed test material in mononuclear cells with chromic oxide and increased neutrophils, protein, lactic dehydrogenase and cellular debris with basic chromium sulfate. The principle effects for both materials were primarily to the respiratory tract. Chromic oxide caused pathological changes in the bronchial and mediastinal lymphatic tissue and lungs, consisting of the presence of pigment-laden macrophages, lymphoid and septal hyperplasia, and interstitial inflammation similar to that observed with other inert dusts. Basic chromium sulfate produced more severe and widespread effects in the nasal cavity, larynx, lungs, and mediastinal lymph node. Effects were characterized by accumulation of foreign material, infiltration of alveolar macrophages, septal cell hyperplasia, and granulomatous and chronic inflammation. Pigment was still present in chromic oxide and, to a lesser extent, in basic chromium sulfate-treated animals after the 13-week recovery period, with partial recovery of the pathological lesions. A NOAEL was not established for either test material, but 4.4 mg/m3 was thought to be near the NOAEL level for subchronic exposure to chromic oxide. The results of this study indicate significant differences in toxicity to the respiratory tract between trivalent chromium compounds chromic oxide and basic chromium sulfate. These are likely related to differences in acidity and water solubility, rather than chromium concentration per se. This conclusion is substantiated by the lack of effect on other internal organs."
730668,Bashar et al. 1997,The teratogenic effects of mercury disulfate and dichromate on pregnant female Wysoto mice,"The treatment of one-hundred pregnant mice with mercury disulfate and dichromate solutions has yielded some interesting results. The embryos inside these mice were at the sixth week of birth development at the time of exposure. After an exposure period of ten to twenty consecutive days, the embryos were shown to develop irregular heart beats and show irregular movement. Once the time for the actual birth of these embryos had arrived, it was discovered that they developed defective limbs, noses, and eyes as a result of being exposed to these two teratogenic heavy metal solutions. Further analysis showed that the Nervous systems of these embryos appeared to be damaged by the exposure to the mercury solution in that they exhibited constant twiching and random responses to stimuli that were not even present. A few of the embryos exposed to the dichromate solution showed a malformation of sex organs and in some cases a change in the normal white coloring.","The teratogenic effects of mercury disulfate and dichromate on pregnant female Wysoto mice Abs: The treatment of one-hundred pregnant mice with mercury disulfate and dichromate solutions has yielded some interesting results. The embryos inside these mice were at the sixth week of birth development at the time of exposure. After an exposure period of ten to twenty consecutive days, the embryos were shown to develop irregular heart beats and show irregular movement. Once the time for the actual birth of these embryos had arrived, it was discovered that they developed defective limbs, noses, and eyes as a result of being exposed to these two teratogenic heavy metal solutions. Further analysis showed that the Nervous systems of these embryos appeared to be damaged by the exposure to the mercury solution in that they exhibited constant twiching and random responses to stimuli that were not even present. A few of the embryos exposed to the dichromate solution showed a malformation of sex organs and in some cases a change in the normal white coloring."
730664,Zhitkovich et al. 1998,Utilization of DNA-protein cross-links as a biomarker of chromium exposure,"Human exposure to carcinogenic Cr(VI) compounds is found among workers in a large number of professional groups, and it can also occur through environmental pollution. A significant number of toxic waste sites contain Cr as a major contaminant. In this paper we summarize our efforts to apply measurements of DNA-protein cross-links (DPC) as test for biologically active doses of Cr(VI). DPC were found at elevated levels in lymphocytes in several human populations with low to medium Cr exposures. At high exposure to Cr(VI), exemplified by a group of Bulgarian chromeplaters, DPC plateaued and adducts' levels were similar to those found in environmentally exposed individuals. Lymphocytic DPC correlated strongly with Cr levels in erythrocytes that are indicative of Cr(VI) exposure. DPC in lymphocytes were not confounded by such variables as smoking, age, body weight, gender, or ethnicity. A new version of the cross-link assay offers improved sensitivity and requires a small amount of biologic material. Preliminary results indicate that the ability of DPC to reach detectable levels at low levels of Cr exposure could be related to a lack of repair of these lesions in lymphoid cells. Cr(III)-mediated cross-links of DNA with peptide glutathione or single amino acids were mutagenic in human cells, with a relationship of higher molecular weight of the peptide/amino acid correlating with a more potent mutagenic response. We speculate that bulky DPC could also have a significant promutagenic effect. The current methodology does not allow specific determination of Cr-induced DPC; however, demonstrated sensitivity of DPC measurements and the assay's large sample capacity may allow this assay to be used as the initial screening test for the occurrence of DNA damage in Cr(VI)-exposed populations.","Utilization of DNA-protein cross-links as a biomarker of chromium exposure Abs: Human exposure to carcinogenic Cr(VI) compounds is found among workers in a large number of professional groups, and it can also occur through environmental pollution. A significant number of toxic waste sites contain Cr as a major contaminant. In this paper we summarize our efforts to apply measurements of DNA-protein cross-links (DPC) as test for biologically active doses of Cr(VI). DPC were found at elevated levels in lymphocytes in several human populations with low to medium Cr exposures. At high exposure to Cr(VI), exemplified by a group of Bulgarian chromeplaters, DPC plateaued and adducts' levels were similar to those found in environmentally exposed individuals. Lymphocytic DPC correlated strongly with Cr levels in erythrocytes that are indicative of Cr(VI) exposure. DPC in lymphocytes were not confounded by such variables as smoking, age, body weight, gender, or ethnicity. A new version of the cross-link assay offers improved sensitivity and requires a small amount of biologic material. Preliminary results indicate that the ability of DPC to reach detectable levels at low levels of Cr exposure could be related to a lack of repair of these lesions in lymphoid cells. Cr(III)-mediated cross-links of DNA with peptide glutathione or single amino acids were mutagenic in human cells, with a relationship of higher molecular weight of the peptide/amino acid correlating with a more potent mutagenic response. We speculate that bulky DPC could also have a significant promutagenic effect. The current methodology does not allow specific determination of Cr-induced DPC; however, demonstrated sensitivity of DPC measurements and the assay's large sample capacity may allow this assay to be used as the initial screening test for the occurrence of DNA damage in Cr(VI)-exposed populations."
730663,Zeidler-Erdely et al. 2008,Pulmonary inflammation and tumor induction in lung tumor susceptible A/J and resistant C57BL/6J mice exposed to welding fume,"ABSTRACT:<br /><br /> Welding fume has been categorized as ""possibly carcinogenic"" to humans. Our objectives were to characterize the lung response to carcinogenic and non-carcinogenic metal-containing welding fumes and to determine if these fumes caused increased lung tumorigenicity in A/J mice, a lung tumor susceptible strain. We exposed male A/J and C57BL/6J, a lung tumor resistant strain, by pharyngeal aspiration four times (once every 3 days) to 85 mug of gas metal arc-mild steel (GMA-MS), GMA-stainless steel (SS), or manual metal arc-SS (MMA-SS) fume, or to 25.5 mug soluble hexavalent chromium (S-Cr). Shams were exposed to saline vehicle. Bronchoalveolar lavage (BAL) was done at 2, 7, and 28 days post-exposure. For the lung tumor study, gross tumor counts and histopathological changes were assessed in A/J mice at 48 and 78 weeks post-exposure.<br /><br /> BAL revealed notable strain-dependent differences with regards to the degree and resolution of the inflammatory response after exposure to the fumes. At 48 weeks, carcinogenic metal-containing GMA-SS fume caused the greatest increase in tumor multiplicity and incidence, but this was not different from sham. By 78 weeks, tumor incidence in the GMA-SS group versus sham approached significance (p = 0.057). A significant increase in perivascular/peribronchial lymphoid infiltrates for the GMA-SS group versus sham and an increased persistence of this fume in lung cells compared to the other welding fumes was found.<br /><br /> The increased persistence of GMA-SS fume in combination with its metal composition may trigger a chronic, but mild, inflammatory state in the lung possibly enhancing tumorigenesis in this susceptible mouse strain.","Pulmonary inflammation and tumor induction in lung tumor susceptible A/J and resistant C57BL/6J mice exposed to welding fume Abs: ABSTRACT:<br /><br /> Welding fume has been categorized as ""possibly carcinogenic"" to humans. Our objectives were to characterize the lung response to carcinogenic and non-carcinogenic metal-containing welding fumes and to determine if these fumes caused increased lung tumorigenicity in A/J mice, a lung tumor susceptible strain. We exposed male A/J and C57BL/6J, a lung tumor resistant strain, by pharyngeal aspiration four times (once every 3 days) to 85 mug of gas metal arc-mild steel (GMA-MS), GMA-stainless steel (SS), or manual metal arc-SS (MMA-SS) fume, or to 25.5 mug soluble hexavalent chromium (S-Cr). Shams were exposed to saline vehicle. Bronchoalveolar lavage (BAL) was done at 2, 7, and 28 days post-exposure. For the lung tumor study, gross tumor counts and histopathological changes were assessed in A/J mice at 48 and 78 weeks post-exposure.<br /><br /> BAL revealed notable strain-dependent differences with regards to the degree and resolution of the inflammatory response after exposure to the fumes. At 48 weeks, carcinogenic metal-containing GMA-SS fume caused the greatest increase in tumor multiplicity and incidence, but this was not different from sham. By 78 weeks, tumor incidence in the GMA-SS group versus sham approached significance (p = 0.057). A significant increase in perivascular/peribronchial lymphoid infiltrates for the GMA-SS group versus sham and an increased persistence of this fume in lung cells compared to the other welding fumes was found.<br /><br /> The increased persistence of GMA-SS fume in combination with its metal composition may trigger a chronic, but mild, inflammatory state in the lung possibly enhancing tumorigenesis in this susceptible mouse strain."
730662,Werfel et al. 1998,Elevated DNA single-strand breakage frequencies in lymphocytes of welders exposed to chromium and nickel,"DNA damage (alkaline filter elution) and sister chromatid exchange (SCE) frequencies were measured in lymphocytes of 39 welders and 39 controls. The welders showed a significantly higher rate of DNA single-strand breakages and significantly elevated SCE values. These results are not in accordance with those of a former study in which only DNA-protein cross-links were measured. The different results may be explained on the basis of different exposure levels for chromium(VI) and nickel. Both methods are not specific but sensitive enough to measure genotoxic damage after occupational exposure to chromium(VI) and nickel in the range of threshold values for the workplace on a collective basis. Additionally, the results indicate that DNA single-strand breakage and DNA-protein cross-links show different increases depending on the exposure levels for chromium and nickel.","Elevated DNA single-strand breakage frequencies in lymphocytes of welders exposed to chromium and nickel Abs: DNA damage (alkaline filter elution) and sister chromatid exchange (SCE) frequencies were measured in lymphocytes of 39 welders and 39 controls. The welders showed a significantly higher rate of DNA single-strand breakages and significantly elevated SCE values. These results are not in accordance with those of a former study in which only DNA-protein cross-links were measured. The different results may be explained on the basis of different exposure levels for chromium(VI) and nickel. Both methods are not specific but sensitive enough to measure genotoxic damage after occupational exposure to chromium(VI) and nickel in the range of threshold values for the workplace on a collective basis. Additionally, the results indicate that DNA single-strand breakage and DNA-protein cross-links show different increases depending on the exposure levels for chromium and nickel."
730661,Wang et al. 2010,"Hexavalent chromium induced ROS formation, Akt, NF-kappaB, and MAPK activation, and TNF-alpha and IL-1alpha production in keratinocytes","In certain cell types, it has been found that, hexavalent chromium could increase ROS formation, activate cell signaling and stimulate the release of cytokines. But, in keratinocytes, these effects have not yet fully been demonstrated. Our aim is to observe the above effects of hexavalent chromium on keratinocytes. By utilizing HaCaT cells and the skin of albino guinea pigs, we showed that hexavalent chromium could increase ROS formation, activate the Akt, NF-kB, and MAPK pathways as well as increase the production of cytokines, including TNF-alpha and IL-1alpha. The release of these cytokines from keratinocytes is considered to be a key participant in the pathogenesis of contact hypersensitivity. Among cement workers, chromium hypersensitivity is an important occupational skin disease issue. Therefore, the observations of our study help us better understand the role of hexavalent chromium on the development of chromium hypersensitivity, which might provide clues for clinicians in the development of chemopreventative agents for the prevention of chromium hypersensitivity among cement workers.","Hexavalent chromium induced ROS formation, Akt, NF-kappaB, and MAPK activation, and TNF-alpha and IL-1alpha production in keratinocytes Abs: In certain cell types, it has been found that, hexavalent chromium could increase ROS formation, activate cell signaling and stimulate the release of cytokines. But, in keratinocytes, these effects have not yet fully been demonstrated. Our aim is to observe the above effects of hexavalent chromium on keratinocytes. By utilizing HaCaT cells and the skin of albino guinea pigs, we showed that hexavalent chromium could increase ROS formation, activate the Akt, NF-kB, and MAPK pathways as well as increase the production of cytokines, including TNF-alpha and IL-1alpha. The release of these cytokines from keratinocytes is considered to be a key participant in the pathogenesis of contact hypersensitivity. Among cement workers, chromium hypersensitivity is an important occupational skin disease issue. Therefore, the observations of our study help us better understand the role of hexavalent chromium on the development of chromium hypersensitivity, which might provide clues for clinicians in the development of chemopreventative agents for the prevention of chromium hypersensitivity among cement workers."
730660,Wang et al. 2010,N-acetylcysteine inhibits chromium hypersensitivity in coadjuvant chromium-sensitized albino guinea pigs by suppressing the effects of reactive oxygen species,"Chromium hypersensitivity is an important issue in occupational skin disease. When hexavalent chromium enters the cell, it can be reduced to trivalent chromium, resulting in the formation of reactive oxygen species (ROS). ROS are considered to play an important role in the progression of allergic contact dermatitis. N-acetylcysteine (NAC) could increase glutathione levels in the skin and act as an antioxidant.<br /><br /> We attempted to demonstrate that NAC could inhibit chromium hypersensitivity in a coadjuvant chromium-sensitized albino guinea pig model by counteracting the formation of ROS.<br /><br /> We utilized a coadjuvant chromium-sensitized albino guinea pig model to evaluate both the severity of the skin reaction by intradermal and epicutaneous elicitation tests and the sensitization rate of chromium hypersensitivity in NAC-treated and NAC-untreated albino guinea pigs (GP). Furthermore, three ROS parameters, including H(2)O(2,) malondialdehyde (MDA) levels in the skin and the oxygen radical absorbance capacity (ORAC) in plasma, were analyzed in NAC-treated and NAC-untreated coadjuvant chromium-sensitized albino GP.<br /><br /> The severity of the skin reaction in the intradermal and epicutaneous elicitation test significantly diminished when the albino GP were treated with a dose of 1200 mg/kg/day of NAC. This dose also significantly decreased the sensitization rate of chromium hypersensitivity. In addition, treatment with 1200 mg/kg/day of NAC significantly reduced the H(2)O(2) and MDA levels in the skin and significantly increased the ORAC in the plasma of albino GP. Therefore, NAC could be a potential chemopreventative agent to prevent the progression of chromium hypersensitivity.","N-acetylcysteine inhibits chromium hypersensitivity in coadjuvant chromium-sensitized albino guinea pigs by suppressing the effects of reactive oxygen species Abs: Chromium hypersensitivity is an important issue in occupational skin disease. When hexavalent chromium enters the cell, it can be reduced to trivalent chromium, resulting in the formation of reactive oxygen species (ROS). ROS are considered to play an important role in the progression of allergic contact dermatitis. N-acetylcysteine (NAC) could increase glutathione levels in the skin and act as an antioxidant.<br /><br /> We attempted to demonstrate that NAC could inhibit chromium hypersensitivity in a coadjuvant chromium-sensitized albino guinea pig model by counteracting the formation of ROS.<br /><br /> We utilized a coadjuvant chromium-sensitized albino guinea pig model to evaluate both the severity of the skin reaction by intradermal and epicutaneous elicitation tests and the sensitization rate of chromium hypersensitivity in NAC-treated and NAC-untreated albino guinea pigs (GP). Furthermore, three ROS parameters, including H(2)O(2,) malondialdehyde (MDA) levels in the skin and the oxygen radical absorbance capacity (ORAC) in plasma, were analyzed in NAC-treated and NAC-untreated coadjuvant chromium-sensitized albino GP.<br /><br /> The severity of the skin reaction in the intradermal and epicutaneous elicitation test significantly diminished when the albino GP were treated with a dose of 1200 mg/kg/day of NAC. This dose also significantly decreased the sensitization rate of chromium hypersensitivity. In addition, treatment with 1200 mg/kg/day of NAC significantly reduced the H(2)O(2) and MDA levels in the skin and significantly increased the ORAC in the plasma of albino GP. Therefore, NAC could be a potential chemopreventative agent to prevent the progression of chromium hypersensitivity."
730659,Vanoirbeek et al. 2003,Kinetics of an intratracheally administered chromium catalyst in rats,"Chromium-based catalysts are used for the synthesis of polyethylene, but little is known about the hazard and biomonitoring possibilities of this type of chromium for workers who may be occupationally exposed to such compounds. Therefore, the bioavailability and toxicokinetics of chromium were studied in male Wistar rats after a single intratracheal instillation (2 ml/kg body weight) of various doses (1, 5, or 25 mg/kg body weight) of the catalyst (approximately 1% chromium bound to an amorphous silica matrix), either before (CAT-Cr[III]) or after (CAT-Cr[VI]) heat treatment. The results were compared with those of equivalent amounts of two chromium salts (CrCl(3) and K(2) Cr(2) O (7). Each dose group was composed of three rats. The concentration of chromium was determined by atomic absorption spectrometry in urine (collected daily for 7 d) and in plasma, erythrocytes, lung, and liver tissue obtained 2 d (only highest concentration) and 7 d after dosing. On d 2, a significant increase in lung weight was found in the animals treated with the highest dose of the hexavalent Cr products. On d 7, on the basis of body weights, lung weights, and lung histology, there was no overt toxicity, except after the highest dose of CAT-Cr(VI). The elimination of all forms of chromium was apparently monoexponential, with calculated half-life elimination times in urine of 4-11 h for Cr(III) (CAT-Cr[III] and CrCl3 ) and 8-21 h for Cr(VI) (CAT-Cr[VI] and K(2) Cr(2) O(7). On d 2, the erythro-cytes Cr concentrations were significantly higher for the hexavalent Cr products than for the trivalent Cr products. After 7 d, the erythrocytes Cr concentrations were significantly increased above control values (3 microg/L) only in rats treated with the 2 highest doses of Cr( VI) compounds (12 and 64 microg/L for K(2) Cr(2) O(7), and 14 and 79 microg/L for CAT-Cr[VI]). The present study shows that intratracheally instilled Cr(VI) and Cr(III) have different toxicokinetic profiles and that the Cr(VI) catalyst has the same bioavailability and excretion kinetics as a water-soluble Cr(VI) salt. Exposure to chromium compounds could be monitored by measuring Cr concen-trations in urine (shortly after exposure) and in erythrocytes (also at later time points after high Cr[VI] exposure).","Kinetics of an intratracheally administered chromium catalyst in rats Abs: Chromium-based catalysts are used for the synthesis of polyethylene, but little is known about the hazard and biomonitoring possibilities of this type of chromium for workers who may be occupationally exposed to such compounds. Therefore, the bioavailability and toxicokinetics of chromium were studied in male Wistar rats after a single intratracheal instillation (2 ml/kg body weight) of various doses (1, 5, or 25 mg/kg body weight) of the catalyst (approximately 1% chromium bound to an amorphous silica matrix), either before (CAT-Cr[III]) or after (CAT-Cr[VI]) heat treatment. The results were compared with those of equivalent amounts of two chromium salts (CrCl(3) and K(2) Cr(2) O (7). Each dose group was composed of three rats. The concentration of chromium was determined by atomic absorption spectrometry in urine (collected daily for 7 d) and in plasma, erythrocytes, lung, and liver tissue obtained 2 d (only highest concentration) and 7 d after dosing. On d 2, a significant increase in lung weight was found in the animals treated with the highest dose of the hexavalent Cr products. On d 7, on the basis of body weights, lung weights, and lung histology, there was no overt toxicity, except after the highest dose of CAT-Cr(VI). The elimination of all forms of chromium was apparently monoexponential, with calculated half-life elimination times in urine of 4-11 h for Cr(III) (CAT-Cr[III] and CrCl3 ) and 8-21 h for Cr(VI) (CAT-Cr[VI] and K(2) Cr(2) O(7). On d 2, the erythro-cytes Cr concentrations were significantly higher for the hexavalent Cr products than for the trivalent Cr products. After 7 d, the erythrocytes Cr concentrations were significantly increased above control values (3 microg/L) only in rats treated with the 2 highest doses of Cr( VI) compounds (12 and 64 microg/L for K(2) Cr(2) O(7), and 14 and 79 microg/L for CAT-Cr[VI]). The present study shows that intratracheally instilled Cr(VI) and Cr(III) have different toxicokinetic profiles and that the Cr(VI) catalyst has the same bioavailability and excretion kinetics as a water-soluble Cr(VI) salt. Exposure to chromium compounds could be monitored by measuring Cr concen-trations in urine (shortly after exposure) and in erythrocytes (also at later time points after high Cr[VI] exposure)."
730658,Toya et al. 1999,Hexavalent chromium responsible for lung lesions induced by intratracheal instillation of chromium fumes in rats,"Lung toxicity of chromium fumes (Cr fumes) was examined by a single intratracheal instillation into rats of 10.6 mg and 21.3 mg Cr fumes/kg body weight and by repeated (3 times) instillations of 10.8 mg and 21.7 mg Cr fumes/kg. The pathological changes were compared with those induced by single administrations of 3.2 mg and 19.2 mg Na2CO3 solution-insoluble fraction of Cr fumes (Cr-Fr)/kg and 20.8 mg commercially available chromium (III) oxide powder (Cr (III) oxide)/kg. Single and repeated administrations of Cr fumes suppressed growth rate in a dose-dependent manner, but administrations of Cr-Fr and Cr (III) oxide did not. A single administration of Cr fumes produced granulomas in the entire airways and alveoli with progressive fibrotic changes, as well as severe mobilization and destruction of macrophages and foamy cells. Those histopathological changes were aggravated by the repeated administration of Cr fumes. On the other hand, single administrations of Cr-Fr and Cr (III) oxide produced no remarkable histopathological changes. Cr fumes were found to be composed of 73.5% chromium (III) oxide and 26.5% chromium (VI) oxide. The primary particles of Cr fumes and Cr-Fr were similar, 0.02 micron in size (sigma g: 1.25), and Cr (III) oxide particles were 0.30 micron in size (sigma g: 1.53), measured by analytical electron microscopy (ATEM). Diffuse clusters of the primary particles in Cr fumes were identified as Cr (VI) oxide. The present results suggested that the lung toxicity of Cr fumes was mainly caused by these Cr (VI) oxide (CrO3) particles in Cr fumes.","Hexavalent chromium responsible for lung lesions induced by intratracheal instillation of chromium fumes in rats Abs: Lung toxicity of chromium fumes (Cr fumes) was examined by a single intratracheal instillation into rats of 10.6 mg and 21.3 mg Cr fumes/kg body weight and by repeated (3 times) instillations of 10.8 mg and 21.7 mg Cr fumes/kg. The pathological changes were compared with those induced by single administrations of 3.2 mg and 19.2 mg Na2CO3 solution-insoluble fraction of Cr fumes (Cr-Fr)/kg and 20.8 mg commercially available chromium (III) oxide powder (Cr (III) oxide)/kg. Single and repeated administrations of Cr fumes suppressed growth rate in a dose-dependent manner, but administrations of Cr-Fr and Cr (III) oxide did not. A single administration of Cr fumes produced granulomas in the entire airways and alveoli with progressive fibrotic changes, as well as severe mobilization and destruction of macrophages and foamy cells. Those histopathological changes were aggravated by the repeated administration of Cr fumes. On the other hand, single administrations of Cr-Fr and Cr (III) oxide produced no remarkable histopathological changes. Cr fumes were found to be composed of 73.5% chromium (III) oxide and 26.5% chromium (VI) oxide. The primary particles of Cr fumes and Cr-Fr were similar, 0.02 micron in size (sigma g: 1.25), and Cr (III) oxide particles were 0.30 micron in size (sigma g: 1.53), measured by analytical electron microscopy (ATEM). Diffuse clusters of the primary particles in Cr fumes were identified as Cr (VI) oxide. The present results suggested that the lung toxicity of Cr fumes was mainly caused by these Cr (VI) oxide (CrO3) particles in Cr fumes."
730656,Spiekstra et al. 2005,"Induction of cytokine (interleukin-1alpha and tumor necrosis factor-alpha) and chemokine (CCL20, CCL27, and CXCL8) alarm signals after allergen and irritant exposure","The immune system is called into action by alarm signals generated from injured tissues. We examined the nature of these alarm signals after exposure of skin residential cells to contact allergens (nickel sulfate and potassium dichromate) and a contact irritant [sodium dodecyl sulfate (SDS)]. Nickel sulfate, potassium dichromate, and SDS were applied topically to the stratum corneum of human skin equivalents. A similar concentration-dependent increase in chemokine (CCL20, CCL27, and CXCL8) secretion was observed for all three chemicals. Exposure to nickel sulfate and SDS was investigated in more detail: similar to chemokine secretion, no difference was observed in the time- and concentration-dependent increase in pro-inflammatory cytokine [interleukin-1alpha (IL-1alpha) and tumor necrosis factor-alpha (TNF-alpha)] secretion. Maximal increase in IL-1alpha secretion occurred within 2 h after exposure to both nickel sulfate and SDS and prior to increased chemokine secretion. TNF-alpha secretion was detectable 8 h after chemical exposure. After allergen or irritant exposure, increased CCL20 and CXCL8, but not CCL27, secretion was inhibited by neutralizing human antibodies to either IL-1alpha or TNF-alpha. Our data show that alarm signals consist of primary and secondary signals. IL-1alpha and TNF-alpha are released as primary alarm signals, which trigger the release of secondary chemokine (CCL20 and CXCL8) alarm signals. However, some chemokines, for example, CCL27 can be secreted in an IL-1alpha and TNF-alpha independent manner. Our data suggest that skin residential cells respond to both allergen and irritant exposure by releasing mediators that initiate infiltration of immune responsive cells into the skin.","Induction of cytokine (interleukin-1alpha and tumor necrosis factor-alpha) and chemokine (CCL20, CCL27, and CXCL8) alarm signals after allergen and irritant exposure Abs: The immune system is called into action by alarm signals generated from injured tissues. We examined the nature of these alarm signals after exposure of skin residential cells to contact allergens (nickel sulfate and potassium dichromate) and a contact irritant [sodium dodecyl sulfate (SDS)]. Nickel sulfate, potassium dichromate, and SDS were applied topically to the stratum corneum of human skin equivalents. A similar concentration-dependent increase in chemokine (CCL20, CCL27, and CXCL8) secretion was observed for all three chemicals. Exposure to nickel sulfate and SDS was investigated in more detail: similar to chemokine secretion, no difference was observed in the time- and concentration-dependent increase in pro-inflammatory cytokine [interleukin-1alpha (IL-1alpha) and tumor necrosis factor-alpha (TNF-alpha)] secretion. Maximal increase in IL-1alpha secretion occurred within 2 h after exposure to both nickel sulfate and SDS and prior to increased chemokine secretion. TNF-alpha secretion was detectable 8 h after chemical exposure. After allergen or irritant exposure, increased CCL20 and CXCL8, but not CCL27, secretion was inhibited by neutralizing human antibodies to either IL-1alpha or TNF-alpha. Our data show that alarm signals consist of primary and secondary signals. IL-1alpha and TNF-alpha are released as primary alarm signals, which trigger the release of secondary chemokine (CCL20 and CXCL8) alarm signals. However, some chemokines, for example, CCL27 can be secreted in an IL-1alpha and TNF-alpha independent manner. Our data suggest that skin residential cells respond to both allergen and irritant exposure by releasing mediators that initiate infiltration of immune responsive cells into the skin."
730654,Sellappa et al. 2010,Evaluation of DNA damage induction and repair inhibition in welders exposed to hexavalent chromium,"The soluble hexavalent chromium Cr (VI) used in industrial welding is an environmental contaminant widely recognized to act as a carcinogen, mutagen and teratogen towards humans and animals. The carcinogenic potential of metals is a major issue in defining human health risk from exposure. In the present investigation, 93 welders and 60 control subjects with similar mean ages, smoking prevalences and alcohol consumption were enrolled for DNA damage analysis in blood leucocytes by Micronucleus assay (MN) and the Comet assay. DNA repair inhibition was also analyzed by assessing XPD gene polymorphism. Welders showed a significant increase in micronucleated cells compared to controls with respect to their smoking habits and alcohol consumption, age and years of exposure (P<0.05). Results indicated that the welders had a larger mean comet tail length than that of the controls (P<0.05). The current study suggested that chronic occupational exposure to Cr (VI) during welding could lead to increased levels of DNA damage and repair inhibition.","Evaluation of DNA damage induction and repair inhibition in welders exposed to hexavalent chromium Abs: The soluble hexavalent chromium Cr (VI) used in industrial welding is an environmental contaminant widely recognized to act as a carcinogen, mutagen and teratogen towards humans and animals. The carcinogenic potential of metals is a major issue in defining human health risk from exposure. In the present investigation, 93 welders and 60 control subjects with similar mean ages, smoking prevalences and alcohol consumption were enrolled for DNA damage analysis in blood leucocytes by Micronucleus assay (MN) and the Comet assay. DNA repair inhibition was also analyzed by assessing XPD gene polymorphism. Welders showed a significant increase in micronucleated cells compared to controls with respect to their smoking habits and alcohol consumption, age and years of exposure (P<0.05). Results indicated that the welders had a larger mean comet tail length than that of the controls (P<0.05). The current study suggested that chronic occupational exposure to Cr (VI) during welding could lead to increased levels of DNA damage and repair inhibition."
730651,Pistoor et al. 1996,Novel predictive assay for contact allergens using human skin explant cultures,"Contact allergens sensitize the immune system by the binding to and subsequent activation of Langerhans cells (LCs), the antigen-presenting cells of the skin. At present, new chemicals are usually tested for their contact allergenicity in animal models. To develop an animal-replacing predictive in vivo assay for the identification of potential contact allergens, we compared the effects of epicutaneous application of six known contact allergens, five known irritants and two dermatologically inactive chemicals on LCs in skin biopsy cultures from seven healthy donors. Immunohistochemical analysis of cryostat sections of all the biopsies treated with contact allergens showed 1) a large reduction in the number of LCs in epidermis, as evaluated by a decrease in human leukocyte antigens (HLA)-DR-expressing cells, and CD1a-expressing cells and 2) accumulation of the remaining LCs at the epidermal-dermal junction. In contrast, the irritants, inactive chemicals, and solvents did not induce these changes. Morphometrical analysis indicated that the contact allergen-induced reduction in the number of HLA-DR+ and CD1a+ LCs per millimeter of epidermis was significant and was dependent on the concentration of the contact allergens. Flow cytometric analysis of isolated epidermal cells confirmed the immunohistochemical findings. In combination, these results suggest that the culture of ex vivo human skin explants provides a promising model to predict potential allergenicity of newly produced chemical compounds and can therefore replace current animal models.","Novel predictive assay for contact allergens using human skin explant cultures Abs: Contact allergens sensitize the immune system by the binding to and subsequent activation of Langerhans cells (LCs), the antigen-presenting cells of the skin. At present, new chemicals are usually tested for their contact allergenicity in animal models. To develop an animal-replacing predictive in vivo assay for the identification of potential contact allergens, we compared the effects of epicutaneous application of six known contact allergens, five known irritants and two dermatologically inactive chemicals on LCs in skin biopsy cultures from seven healthy donors. Immunohistochemical analysis of cryostat sections of all the biopsies treated with contact allergens showed 1) a large reduction in the number of LCs in epidermis, as evaluated by a decrease in human leukocyte antigens (HLA)-DR-expressing cells, and CD1a-expressing cells and 2) accumulation of the remaining LCs at the epidermal-dermal junction. In contrast, the irritants, inactive chemicals, and solvents did not induce these changes. Morphometrical analysis indicated that the contact allergen-induced reduction in the number of HLA-DR+ and CD1a+ LCs per millimeter of epidermis was significant and was dependent on the concentration of the contact allergens. Flow cytometric analysis of isolated epidermal cells confirmed the immunohistochemical findings. In combination, these results suggest that the culture of ex vivo human skin explants provides a promising model to predict potential allergenicity of newly produced chemical compounds and can therefore replace current animal models."
730649,Pan et al. 2009,Elucidation of the percutaneous absorption of chromium compounds by functional proteomics,"Chromium compounds are known to be associated with cytotoxicity and carcinogenicity when applied via a skin route. The aim of this study was to evaluate the skin permeability and toxicological profiles of four chromium species. Chromium permeation across the skin, as determined by an in vitro Franz cell, decreased in the order of sodium chromate>potassium chromate>potassium dichromate>chromium nitrate. The uptake of chromium species within the skin generally showed a contrary trend to the results of permeation, although differences among the various compounds were not large. Levels of in vivo skin deposition of the four compounds showed no statistically significant differences. Potassium chromate produced the greatest disruption of the skin structure as determined by HE staining, followed in order by sodium chromate, potassium dichromate, and chromium nitrate. This indicates that hexavalent chromium elicited greater toxicity to the skin compared to trivalent chromium. A similar result was observed for the viability of skin fibroblasts. To improve our understanding of the molecular mechanisms leading to functional changes in proteins, proteomic tools, including 2-DE and MS techniques combined with sequence database correlations, were applied to identify target proteins altered by pathologic states. Eight protein spots, corresponding to cutaneous enzymes involved in energy metabolism and chaperon proteins, which were identified and discussed in this study, were associated with skin cytotoxicity, immunity, and carcinogenesis. In addition, functional proteomics of skin tissues may provide a promising tool for developing therapeutic strategies and can serve as the basis for further research.","Elucidation of the percutaneous absorption of chromium compounds by functional proteomics Abs: Chromium compounds are known to be associated with cytotoxicity and carcinogenicity when applied via a skin route. The aim of this study was to evaluate the skin permeability and toxicological profiles of four chromium species. Chromium permeation across the skin, as determined by an in vitro Franz cell, decreased in the order of sodium chromate>potassium chromate>potassium dichromate>chromium nitrate. The uptake of chromium species within the skin generally showed a contrary trend to the results of permeation, although differences among the various compounds were not large. Levels of in vivo skin deposition of the four compounds showed no statistically significant differences. Potassium chromate produced the greatest disruption of the skin structure as determined by HE staining, followed in order by sodium chromate, potassium dichromate, and chromium nitrate. This indicates that hexavalent chromium elicited greater toxicity to the skin compared to trivalent chromium. A similar result was observed for the viability of skin fibroblasts. To improve our understanding of the molecular mechanisms leading to functional changes in proteins, proteomic tools, including 2-DE and MS techniques combined with sequence database correlations, were applied to identify target proteins altered by pathologic states. Eight protein spots, corresponding to cutaneous enzymes involved in energy metabolism and chaperon proteins, which were identified and discussed in this study, were associated with skin cytotoxicity, immunity, and carcinogenesis. In addition, functional proteomics of skin tissues may provide a promising tool for developing therapeutic strategies and can serve as the basis for further research."
730648,Nersesyan 2003,Cytogenetic effects of hexavalent chromium in Bulgaria,,Cytogenetic effects of hexavalent chromium in Bulgaria Abs: 
730647,Mignini et al. 2009,"Immunological pattern alteration in shoe, hide, and leather industry workers exposed to hexavalent chromium","The aim of this work was to assess the effects of hexavalent chromium [Cr(VI)] on shoe, leather, and hide industry workers, based on the assumption that Cr(VI) can behave as an environmental immunological ""stressor.""<br /><br /> The immunological patterns of 84 male subjects were studied in relation to Cr(VI) hematic and urinary levels. Cr(VI) was measured through atomic absorption. Lymphocyte subsets, mitogen-mediated lymphocyte-proliferation, cytokine levels, and natural killer (NK) cytotoxic activity were also assayed.<br /><br /> The urinary levels of the total amount of Cr(VI) were significantly higher in a subgroup of exposed subjects (group B) than in the control or in the lower exposed (group A). In group B, Cr(VI) caused a decrease in the density of glucocorticoid receptors (GR) on peripheral blood mononuclear cells (PBMC) and a increase of IL-6. Cr(VI) did not modify NK-mediated cytotoxicity, the plasmatic levels of inflammatory cytokines and related soluble receptors, and prostaglandin levels, while it tended to increase lymphocyte sensitivity to mitogens and the production of immunomodulant cytokines (IFN-gamma, IL-4, and IL-2). The experimental addition of Cr(VI) to the in vitro lymphocyte culture determined a significant inhibition of phagocytosis percentage, index, and killing percentage. These effects were neutralized by exogenous IFN-gamma.<br /><br /> Cr(VI) could represent an environmental immunological stressor whose effects can be evaluated through laboratory surveys. The lymphocyte mitogen-induced proliferation, GR receptor on PBMC, and IL-6 plasma levels may represent a discriminating element between Cr(VI)-induced stress and other kinds of stress.","Immunological pattern alteration in shoe, hide, and leather industry workers exposed to hexavalent chromium Abs: The aim of this work was to assess the effects of hexavalent chromium [Cr(VI)] on shoe, leather, and hide industry workers, based on the assumption that Cr(VI) can behave as an environmental immunological ""stressor.""<br /><br /> The immunological patterns of 84 male subjects were studied in relation to Cr(VI) hematic and urinary levels. Cr(VI) was measured through atomic absorption. Lymphocyte subsets, mitogen-mediated lymphocyte-proliferation, cytokine levels, and natural killer (NK) cytotoxic activity were also assayed.<br /><br /> The urinary levels of the total amount of Cr(VI) were significantly higher in a subgroup of exposed subjects (group B) than in the control or in the lower exposed (group A). In group B, Cr(VI) caused a decrease in the density of glucocorticoid receptors (GR) on peripheral blood mononuclear cells (PBMC) and a increase of IL-6. Cr(VI) did not modify NK-mediated cytotoxicity, the plasmatic levels of inflammatory cytokines and related soluble receptors, and prostaglandin levels, while it tended to increase lymphocyte sensitivity to mitogens and the production of immunomodulant cytokines (IFN-gamma, IL-4, and IL-2). The experimental addition of Cr(VI) to the in vitro lymphocyte culture determined a significant inhibition of phagocytosis percentage, index, and killing percentage. These effects were neutralized by exogenous IFN-gamma.<br /><br /> Cr(VI) could represent an environmental immunological stressor whose effects can be evaluated through laboratory surveys. The lymphocyte mitogen-induced proliferation, GR receptor on PBMC, and IL-6 plasma levels may represent a discriminating element between Cr(VI)-induced stress and other kinds of stress."
730646,Maeng et al. 2003,Changes of 8-OH-dG levels in DNA and its base excision repair activity in rat lungs after inhalation exposure to hexavalent chromium,"According to the toxicological and epidemiological studies, hexavalent chromium (Cr) is associated with increase of lung cancer risk. Genotoxic effects, such as chromosomal aberrations, and cellular oxidative DNA damage by reactive oxygen species produced by hexavalent Cr exposure may play an important role in its carcinogenesis. To clarify whether reactive oxygen species are involved in its mechanism, we examined the levels of 8-hydroxydeoxyguanine (8-OH-dG) and its base excision repair activities in the lung tissues of rats that repeatedly inhaled a sodium chromate solution mist for 1, 2, and 3 weeks. The levels of 8-OH-dG increased significantly in the lung tissues of the rats exposed for 1 week at the low concentration (0.18 mg/m(3), P<0.05), as compared with the controls. However, there was no difference in the 8-OH-dG levels at the higher concentration or with more than 2 weeks of exposure. The 8-OH-dG repair activities decreased in a dose-dependent manner during 2 weeks of exposure, on the contrary they recovered at 3 weeks of repeated exposure. These results suggest that the DNA damage caused by hexavalent Cr inhalation is induced by the generation of reactive oxygen species and by inhibition of base excision repair activity during the earlier phase of exposure. However, the 8-OH-dG levels and its repair activities recovered to the level of the controls in the latter inhalation exposure period.","Changes of 8-OH-dG levels in DNA and its base excision repair activity in rat lungs after inhalation exposure to hexavalent chromium Abs: According to the toxicological and epidemiological studies, hexavalent chromium (Cr) is associated with increase of lung cancer risk. Genotoxic effects, such as chromosomal aberrations, and cellular oxidative DNA damage by reactive oxygen species produced by hexavalent Cr exposure may play an important role in its carcinogenesis. To clarify whether reactive oxygen species are involved in its mechanism, we examined the levels of 8-hydroxydeoxyguanine (8-OH-dG) and its base excision repair activities in the lung tissues of rats that repeatedly inhaled a sodium chromate solution mist for 1, 2, and 3 weeks. The levels of 8-OH-dG increased significantly in the lung tissues of the rats exposed for 1 week at the low concentration (0.18 mg/m(3), P<0.05), as compared with the controls. However, there was no difference in the 8-OH-dG levels at the higher concentration or with more than 2 weeks of exposure. The 8-OH-dG repair activities decreased in a dose-dependent manner during 2 weeks of exposure, on the contrary they recovered at 3 weeks of repeated exposure. These results suggest that the DNA damage caused by hexavalent Cr inhalation is induced by the generation of reactive oxygen species and by inhibition of base excision repair activity during the earlier phase of exposure. However, the 8-OH-dG levels and its repair activities recovered to the level of the controls in the latter inhalation exposure period."
730644,Lai et al. 1998,Sister chromatid exchange induced by chromium compounds in human lymphocytes,"The objective of this study was to study was to compare chromium (Cr), nickel-chromium (Ni-Cr), and control groups for sister chromatid exchange (SCE) in lymphocytes to obtain an understanding of the mutagenic effect of Cr(VI) in humans. Subjects totaled 91 persons from the 3 groups, including 14 Cr and 34 Ni-Cr electroplating workers and 43 control group members. Results showed that blood and urine Cr concentrations were highest among Cr workers (11.39 microg/l, 14.7 microg/g creatinine), next highest among Ni-Cr workers (5.28 microg/l, 6.2 microg/g creatinine), and lowest among the control group (2.36 microg/l, NA). After adjustment for smoking habits, SCE/cell values were 10.6, 9.4, and 8.3 for Cr workers, Ni-Cr workers, and controls, respectively. A synergetic effect was shown on HFC (high-frequency cells) percentages for Cr workers who also smoked. Odds ratios were 31.78 and 3.66 that Cr and Ni-Cr workers would have higher HFC percentages than the control group, respectively. The authors conclude that SCE in lymphocytes is useful for evaluation of the biological effects of environmental mutagens.","Sister chromatid exchange induced by chromium compounds in human lymphocytes Abs: The objective of this study was to study was to compare chromium (Cr), nickel-chromium (Ni-Cr), and control groups for sister chromatid exchange (SCE) in lymphocytes to obtain an understanding of the mutagenic effect of Cr(VI) in humans. Subjects totaled 91 persons from the 3 groups, including 14 Cr and 34 Ni-Cr electroplating workers and 43 control group members. Results showed that blood and urine Cr concentrations were highest among Cr workers (11.39 microg/l, 14.7 microg/g creatinine), next highest among Ni-Cr workers (5.28 microg/l, 6.2 microg/g creatinine), and lowest among the control group (2.36 microg/l, NA). After adjustment for smoking habits, SCE/cell values were 10.6, 9.4, and 8.3 for Cr workers, Ni-Cr workers, and controls, respectively. A synergetic effect was shown on HFC (high-frequency cells) percentages for Cr workers who also smoked. Odds ratios were 31.78 and 3.66 that Cr and Ni-Cr workers would have higher HFC percentages than the control group, respectively. The authors conclude that SCE in lymphocytes is useful for evaluation of the biological effects of environmental mutagens."
730643,Kuo et al. 2003,Chromium (VI) induced oxidative damage to DNA: increase of urinary 8-hydroxydeoxyguanosine concentrations (8-OHdG) among electroplating workers,"To investigate the concentration of urinary 8-hydroxydeoxyguanosine (8-OHdG) among electroplating workers in Taiwan.<br /><br /> Fifty workers were selected from five chromium (Cr) electroplating plants in central Taiwan. The 20 control subjects were office workers with no previous exposure to Cr. Urinary 8-OHdG concentrations were determined using high performance liquid chromatography with electrochemical detection.<br /><br /> Urinary 8-OHdG concentrations among Cr workers (1149.5 pmol/kg/day) were higher than those in the control group (730.2 pmol/kg/day). There was a positive correlation between urinary 8-OHdG concentrations and urinary Cr concentration (r = 0.447, p < 0.01), and urinary 8-OHdG correlated positively with airborne Cr concentration (r = 0.285). Using multiple regression analysis, the factors that affected urinary 8-OHdG concentrations were alcohol, the common cold, and high urinary Cr concentration. There was a high correlation of urinary 8-OHdG with both smoking and drinking, but multiple regression analysis showed that smoking was not a significant factor. Age and gender were also non-significant factors.<br /><br /> 8-OHdG, which is an indicator of oxidative DNA damage, was a sensitive biomarker for Cr exposure.","Chromium (VI) induced oxidative damage to DNA: increase of urinary 8-hydroxydeoxyguanosine concentrations (8-OHdG) among electroplating workers Abs: To investigate the concentration of urinary 8-hydroxydeoxyguanosine (8-OHdG) among electroplating workers in Taiwan.<br /><br /> Fifty workers were selected from five chromium (Cr) electroplating plants in central Taiwan. The 20 control subjects were office workers with no previous exposure to Cr. Urinary 8-OHdG concentrations were determined using high performance liquid chromatography with electrochemical detection.<br /><br /> Urinary 8-OHdG concentrations among Cr workers (1149.5 pmol/kg/day) were higher than those in the control group (730.2 pmol/kg/day). There was a positive correlation between urinary 8-OHdG concentrations and urinary Cr concentration (r = 0.447, p < 0.01), and urinary 8-OHdG correlated positively with airborne Cr concentration (r = 0.285). Using multiple regression analysis, the factors that affected urinary 8-OHdG concentrations were alcohol, the common cold, and high urinary Cr concentration. There was a high correlation of urinary 8-OHdG with both smoking and drinking, but multiple regression analysis showed that smoking was not a significant factor. Age and gender were also non-significant factors.<br /><br /> 8-OHdG, which is an indicator of oxidative DNA damage, was a sensitive biomarker for Cr exposure."
730642,Klein et al. 2001,Carcinogenicity assays of wood dust and wood additives in rats exposed by long-term inhalation,"This study evaluates whether wood dust and/or wood preservatives develop a carcinogenic potential against the tissues of the airways of rats.<br /><br /> The formation of tumors of the respiratory tract after exposure to wood dust was studied in six groups of approximately 60 female Fischer 344 rats exposed by long-term inhalation to mean concentrations of (1) 18 mg/m3 of untreated oak wood dust, (2) wood preservatives containing ca. 1 microgram/m3 lindane and 0.2 microgram/m3 of pentachlorophenol (PCP) in the exposure air, or lindane and 18 micrograms/m3 of PCP (group lindane/PCP vapors, and group oak wood treated with lindane/PCP), (3) 21 or 39 micrograms/m3 of sodium dichromate (calculated as CrO3, group chromate aerosol and group oak wood with chromate), and 72 micrograms/m3 of N-nitrosodimethylamine vapors as positive control. The negative control group consisted of 115 animals (sham-exposed).<br /><br /> Tumors of the nasal cavity developed in two rats exposed to chromate aerosol or in combination with wood dust (2/102, 2%). Malignant tumors of the lower respiratory tract were induced only in exposed groups of rats (three adenocarcinomas of the lung and four bronchiolar lung carcinomas, 7/254, 2.8%). More respiratory tract tumors were observed in rats exposed to chromate or wood with chromate (5/102, 5%), also in groups exposed to oak wood dust (oak untreated, oak + chromate, oak + lindane/PCP; together 5/155, 3.2%). Analysis of 'unpreserved' oak wood dust revealed up to 5 micrograms/m3 of chromate. When this exposure was taken into account, eight of nine animals with respiratory tract tumors (including nasal cavity) had exposure to chromate, while only one tumor occurred in the group lindane/PCP. Otherwise the incidence of systemic tumors was increased in animals exposed to lindane/PCP, due in particular to a significantly increased incidence of liver tumors (OR = 3.7; 1.24-11.3; P = 0.019). Fatal (mucoepidermoid) tumors were induced by N-nitrosodimethylamine (NDMA) in the positive control (14/46, 30%). No such tumors of the respiratory tract were observed in the negative control.<br /><br /> Tumors in the respiratory tract were found only in exposed animals, predominantly in the groups which inhaled oak wood dust and chromate stain. Chromate may play a decisive role for the etiology of tumors of the nasal cavity in wood workers. This assumption should be supported by further dose-response studies.","Carcinogenicity assays of wood dust and wood additives in rats exposed by long-term inhalation Abs: This study evaluates whether wood dust and/or wood preservatives develop a carcinogenic potential against the tissues of the airways of rats.<br /><br /> The formation of tumors of the respiratory tract after exposure to wood dust was studied in six groups of approximately 60 female Fischer 344 rats exposed by long-term inhalation to mean concentrations of (1) 18 mg/m3 of untreated oak wood dust, (2) wood preservatives containing ca. 1 microgram/m3 lindane and 0.2 microgram/m3 of pentachlorophenol (PCP) in the exposure air, or lindane and 18 micrograms/m3 of PCP (group lindane/PCP vapors, and group oak wood treated with lindane/PCP), (3) 21 or 39 micrograms/m3 of sodium dichromate (calculated as CrO3, group chromate aerosol and group oak wood with chromate), and 72 micrograms/m3 of N-nitrosodimethylamine vapors as positive control. The negative control group consisted of 115 animals (sham-exposed).<br /><br /> Tumors of the nasal cavity developed in two rats exposed to chromate aerosol or in combination with wood dust (2/102, 2%). Malignant tumors of the lower respiratory tract were induced only in exposed groups of rats (three adenocarcinomas of the lung and four bronchiolar lung carcinomas, 7/254, 2.8%). More respiratory tract tumors were observed in rats exposed to chromate or wood with chromate (5/102, 5%), also in groups exposed to oak wood dust (oak untreated, oak + chromate, oak + lindane/PCP; together 5/155, 3.2%). Analysis of 'unpreserved' oak wood dust revealed up to 5 micrograms/m3 of chromate. When this exposure was taken into account, eight of nine animals with respiratory tract tumors (including nasal cavity) had exposure to chromate, while only one tumor occurred in the group lindane/PCP. Otherwise the incidence of systemic tumors was increased in animals exposed to lindane/PCP, due in particular to a significantly increased incidence of liver tumors (OR = 3.7; 1.24-11.3; P = 0.019). Fatal (mucoepidermoid) tumors were induced by N-nitrosodimethylamine (NDMA) in the positive control (14/46, 30%). No such tumors of the respiratory tract were observed in the negative control.<br /><br /> Tumors in the respiratory tract were found only in exposed animals, predominantly in the groups which inhaled oak wood dust and chromate stain. Chromate may play a decisive role for the etiology of tumors of the nasal cavity in wood workers. This assumption should be supported by further dose-response studies."
730641,Kim et al. 2004,Subchronic inhalation toxicity of soluble hexavalent chromium trioxide in rats,"We performed a 90-day repeated-dose inhalation toxicity study of soluble hexavalent chromium trioxide (CrO3 (VI)). Male Sprague-Dawley (SD) rats were exposed to doses of CrO3 in the form of 0.5 approximately 5.0 microm aerosol at 0.00, 0.20, 0.50, and 1.25 mg/m3 for 6 h/day, 5 days/week for 13 weeks using inhalation chamber. CrO3 induced decrease of activity, alopecia and nasal hemorrhage. Body weights of the high-dose 1.25-mg/m3 exposure group were significantly lower than those of the control group. Hematological results revealed the reduction of the number of red blood cell and hematocrit values in the 1.25-mg/m3 exposure group. In addition, the hemoglobin values in the 0.50- and 1.25-mg/m3 exposure groups were significantly decreased compared with those of the control group. Clinical biochemical measurements revealed the reduction in total protein, albumin and alanine aminotransferase (ALT) level of the 0.50- and 1.25-mg/m3 exposure groups. Microscopic examination of the lung showed inflammation reactions caused by Cr exposure. In conclusion, the 13-week repeated exposure with soluble CrO3 demonstrated the injury in SD rats with the no observed adverse effect level (NOAEL) under 0.20 mg/m3.","Subchronic inhalation toxicity of soluble hexavalent chromium trioxide in rats Abs: We performed a 90-day repeated-dose inhalation toxicity study of soluble hexavalent chromium trioxide (CrO3 (VI)). Male Sprague-Dawley (SD) rats were exposed to doses of CrO3 in the form of 0.5 approximately 5.0 microm aerosol at 0.00, 0.20, 0.50, and 1.25 mg/m3 for 6 h/day, 5 days/week for 13 weeks using inhalation chamber. CrO3 induced decrease of activity, alopecia and nasal hemorrhage. Body weights of the high-dose 1.25-mg/m3 exposure group were significantly lower than those of the control group. Hematological results revealed the reduction of the number of red blood cell and hematocrit values in the 1.25-mg/m3 exposure group. In addition, the hemoglobin values in the 0.50- and 1.25-mg/m3 exposure groups were significantly decreased compared with those of the control group. Clinical biochemical measurements revealed the reduction in total protein, albumin and alanine aminotransferase (ALT) level of the 0.50- and 1.25-mg/m3 exposure groups. Microscopic examination of the lung showed inflammation reactions caused by Cr exposure. In conclusion, the 13-week repeated exposure with soluble CrO3 demonstrated the injury in SD rats with the no observed adverse effect level (NOAEL) under 0.20 mg/m3."
730640,Kim et al. 1999,Exposure to hexavalent chromium does not increase 8-hydroxydeoxyguanosine levels in Korean chromate pigment workers,"This study was performed to determine whether chromium exposure increased 8-hydroxydeoxyguanosine levels in respiratory epithelial and white blood cells of chromate pigment workers. The subjects of this study were 22 chromium pigment workers and 16 controls in a chromate pigments factory. To estimate the level of exposure, hexavalent chromium concentrations in the factory air were measured. Chrominum concentrations of venous blood and spot urine, and 8-hydroxydeoxyguanosine levels in DNA extracted from sputum and white blood cells were determined. Correlation coefficients were calculated between them and their statistical significance was tested. Hexavalent chromium concentration in the factory air ranged from below limit of detection to 0.5150 mg/m3. Chromium levels in blood and 8-hydroxydeoxyguanosine levels in DNA extracted from venous blood and sputum were not statistically different between the two groups. Urine chromium level was significantly higher among workers. Among the correlation coefficients between blood chromium concentration, urine chromium concentration, blood 8-OH-dG level, and sputum 8-OH-dG level, none was statistically significant for workers, controls, and total subjects. Duration of employment did not show any significant correlation with those four variables, either. These results suggest that neither the hydroxyl radical nor 8-hydroxydeoxyguanosine is formed by the reduction of hexavalent chromium, or that one or both of these is formed and then effectively removed by oxygen free radical scavengers or 8-hydroxydeoxyguanosine repair enzymes. Since increased exposure to hexavalent chromium did not result in increased 8-hydroxydeoxyguanosine levels, it is unlikely that hexavalent chromium induces lung cancer through 8-hydroxydeoxyguanosine formation.","Exposure to hexavalent chromium does not increase 8-hydroxydeoxyguanosine levels in Korean chromate pigment workers Abs: This study was performed to determine whether chromium exposure increased 8-hydroxydeoxyguanosine levels in respiratory epithelial and white blood cells of chromate pigment workers. The subjects of this study were 22 chromium pigment workers and 16 controls in a chromate pigments factory. To estimate the level of exposure, hexavalent chromium concentrations in the factory air were measured. Chrominum concentrations of venous blood and spot urine, and 8-hydroxydeoxyguanosine levels in DNA extracted from sputum and white blood cells were determined. Correlation coefficients were calculated between them and their statistical significance was tested. Hexavalent chromium concentration in the factory air ranged from below limit of detection to 0.5150 mg/m3. Chromium levels in blood and 8-hydroxydeoxyguanosine levels in DNA extracted from venous blood and sputum were not statistically different between the two groups. Urine chromium level was significantly higher among workers. Among the correlation coefficients between blood chromium concentration, urine chromium concentration, blood 8-OH-dG level, and sputum 8-OH-dG level, none was statistically significant for workers, controls, and total subjects. Duration of employment did not show any significant correlation with those four variables, either. These results suggest that neither the hydroxyl radical nor 8-hydroxydeoxyguanosine is formed by the reduction of hexavalent chromium, or that one or both of these is formed and then effectively removed by oxygen free radical scavengers or 8-hydroxydeoxyguanosine repair enzymes. Since increased exposure to hexavalent chromium did not result in increased 8-hydroxydeoxyguanosine levels, it is unlikely that hexavalent chromium induces lung cancer through 8-hydroxydeoxyguanosine formation."
730639,Kalahasthi et al. 2006,Effect of chromium(VI) on the status of plasma lipid peroxidation and erythrocyte antioxidant enzymes in chromium plating workers,"The present study was carried out to determine the effect of chromium(VI) on the status of plasma lipid peroxidation and erythrocyte antioxidant enzymes in workers exposed to chromium during chromium plating process.<br /><br /> Fifty subjects working in chromium plating process formed the study group. An equal number of age-sex matched subjects working in administrative units formed the control group. The control subjects were residing in the same city but away from the work place of study group subjects. Urinary chromium levels were determined by using a graphite furnace atomic absorption spectrophotometer. The plasma lipid peroxidation and erythrocyte antioxidant enzymes were determined by using spectrophotmetric methods.<br /><br /> A significant increase of plasma lipid peroxidation and a significant decrease of superoxide dismutase and glutathione peroxidase levels were noted in the study group as compared with the controls. The level of plasma lipid peroxidation was positively and erythrocyte antioxidant enzymes were negatively and significantly correlated with chromium levels in urine. Multiple regression analysis was assessed the oxidative stress associated with chromium and life style confounding factors such as BMI, coffee, tea, alcohol and smoking. The multiple regression analysis showed that the urine chromium levels >10 micro g/g of creatinine, smoking, consumption of green vegetables and BMI variables were significantly associated with the levels of oxidative stress.<br /><br /> The results show that the increased plasma lipid peroxidation and decreased antioxidant enzymes (superoxide dismutase and glutathione peroxidase) observed in chromium-exposed workers could be used as biomarkers of oxidative stress.","Effect of chromium(VI) on the status of plasma lipid peroxidation and erythrocyte antioxidant enzymes in chromium plating workers Abs: The present study was carried out to determine the effect of chromium(VI) on the status of plasma lipid peroxidation and erythrocyte antioxidant enzymes in workers exposed to chromium during chromium plating process.<br /><br /> Fifty subjects working in chromium plating process formed the study group. An equal number of age-sex matched subjects working in administrative units formed the control group. The control subjects were residing in the same city but away from the work place of study group subjects. Urinary chromium levels were determined by using a graphite furnace atomic absorption spectrophotometer. The plasma lipid peroxidation and erythrocyte antioxidant enzymes were determined by using spectrophotmetric methods.<br /><br /> A significant increase of plasma lipid peroxidation and a significant decrease of superoxide dismutase and glutathione peroxidase levels were noted in the study group as compared with the controls. The level of plasma lipid peroxidation was positively and erythrocyte antioxidant enzymes were negatively and significantly correlated with chromium levels in urine. Multiple regression analysis was assessed the oxidative stress associated with chromium and life style confounding factors such as BMI, coffee, tea, alcohol and smoking. The multiple regression analysis showed that the urine chromium levels >10 micro g/g of creatinine, smoking, consumption of green vegetables and BMI variables were significantly associated with the levels of oxidative stress.<br /><br /> The results show that the increased plasma lipid peroxidation and decreased antioxidant enzymes (superoxide dismutase and glutathione peroxidase) observed in chromium-exposed workers could be used as biomarkers of oxidative stress."
730638,Izzotti et al. 2002,Selective induction of gene expression in rat lung by hexavalent chromium,"Multigene-expression analysis provides a formidable tool for evaluating cellular functions, under either physiological or pathological conditions, and for assessing their modulation by exogenous agents. We investigated multigene expression in the liver and lung of rats receiving intratracheal instillations of sodium dichromate for 3 consecutive days. Nylon membrane cDNA arrays were hybridized with standardized amounts of (32)P-labeled probes, and the results were normalized by making reference to housekeeping genes. The basal expression of 52 of 216 tested genes was 2.1-11.1 times higher in the liver than in the lung of control rats. No alteration of gene expression occurred in the liver of chromium(VI)-treated rats, consistent with the fact that this metal species, being reduced upstream, can exert effects only locally but not at a distance from the respiratory tract. In contrast, the expression of 56 genes was increased 2.1 to 3.0 times in the lung as an early response to chromium(VI) administration. The altered genes are involved in the metabolic reduction of chromium(VI) and in a variety of interconnected functions, such as multidrug resistance and stress response, protein and DNA repair mechanisms, signal transduction pathways, apoptosis, and cell-cycle modulation. Thus, short-term treatment with chromium(VI) by intratracheal administration triggered a variety of defense processes in the lung. Although the use of selected genes does not provide an exhaustive picture of overall gene expression, these findings contribute to our understanding of chromium toxicology and provide a further mechanistic support to the involvement of thresholds in chromium(VI) carcinogenesis.","Selective induction of gene expression in rat lung by hexavalent chromium Abs: Multigene-expression analysis provides a formidable tool for evaluating cellular functions, under either physiological or pathological conditions, and for assessing their modulation by exogenous agents. We investigated multigene expression in the liver and lung of rats receiving intratracheal instillations of sodium dichromate for 3 consecutive days. Nylon membrane cDNA arrays were hybridized with standardized amounts of (32)P-labeled probes, and the results were normalized by making reference to housekeeping genes. The basal expression of 52 of 216 tested genes was 2.1-11.1 times higher in the liver than in the lung of control rats. No alteration of gene expression occurred in the liver of chromium(VI)-treated rats, consistent with the fact that this metal species, being reduced upstream, can exert effects only locally but not at a distance from the respiratory tract. In contrast, the expression of 56 genes was increased 2.1 to 3.0 times in the lung as an early response to chromium(VI) administration. The altered genes are involved in the metabolic reduction of chromium(VI) and in a variety of interconnected functions, such as multidrug resistance and stress response, protein and DNA repair mechanisms, signal transduction pathways, apoptosis, and cell-cycle modulation. Thus, short-term treatment with chromium(VI) by intratracheal administration triggered a variety of defense processes in the lung. Although the use of selected genes does not provide an exhaustive picture of overall gene expression, these findings contribute to our understanding of chromium toxicology and provide a further mechanistic support to the involvement of thresholds in chromium(VI) carcinogenesis."
730637,Izzotti et al. 2004,Proteomic analysis as related to transcriptome data in the lung of chromium(VI)-treated rats,"Assessing the parallelism between transcriptome data and proteome data represents one of the major challenges of post-genomic research. We evaluated the levels of 380 proteins in lung S12 fractions from Sprague-Dawley rats by antibody microarrays. Approximately half of these proteins were detectable under physiological conditions. There was a poor parallelism between mRNA and protein levels for a subset of 84 coinciding or related activities, whose gene expression had previously been investigated by cDNA array. The proportion of detectable proteins was almost twice as high as the proportion of transcriptionally active genes, which reflects the longer half-life of proteins compared to mRNA. Following the local stimulus provided by a short-term and high-dose exposure to sodium dichromate by the intra-tracheal route, 64 additional proteins were detectable in lung S12 fractions, and the correlation between gene expression and protein levels became significant. Sixteen proteins were increased more than twice following chromium(VI) administration. They included ten activities involved in the positive regulation of the cell cycle, three proteins involved in stress response and protein repair, two pro-apoptotic activities, and one protein involved in lipoprotein catabolism. An increase of P53 protein was detected by Western blot in lung nuclear fractions. Post-genomic analyses, highlighting the stimulation of defence mechanisms triggered by DNA damage, contribute to explain the previously reported discrepancy between the ability of chromium(VI) to induce oxidative stress and genotoxic damage in the lung and its failure to induce lung tumors under comparable experimental conditions. The proteome analysis showed a prominent role of apoptosis, counter-balanced by a positive regulation of the cell cycle aimed at replacing lost cells. In conclusion, our results suggest that, under basal conditions, mRNA undergoes a selective inactivation and post-transcriptional regulation resulting in de-coupling of transcriptome data and proteome data. However, this parallelism is re-established when the cell undergoes genotoxic damage.","Proteomic analysis as related to transcriptome data in the lung of chromium(VI)-treated rats Abs: Assessing the parallelism between transcriptome data and proteome data represents one of the major challenges of post-genomic research. We evaluated the levels of 380 proteins in lung S12 fractions from Sprague-Dawley rats by antibody microarrays. Approximately half of these proteins were detectable under physiological conditions. There was a poor parallelism between mRNA and protein levels for a subset of 84 coinciding or related activities, whose gene expression had previously been investigated by cDNA array. The proportion of detectable proteins was almost twice as high as the proportion of transcriptionally active genes, which reflects the longer half-life of proteins compared to mRNA. Following the local stimulus provided by a short-term and high-dose exposure to sodium dichromate by the intra-tracheal route, 64 additional proteins were detectable in lung S12 fractions, and the correlation between gene expression and protein levels became significant. Sixteen proteins were increased more than twice following chromium(VI) administration. They included ten activities involved in the positive regulation of the cell cycle, three proteins involved in stress response and protein repair, two pro-apoptotic activities, and one protein involved in lipoprotein catabolism. An increase of P53 protein was detected by Western blot in lung nuclear fractions. Post-genomic analyses, highlighting the stimulation of defence mechanisms triggered by DNA damage, contribute to explain the previously reported discrepancy between the ability of chromium(VI) to induce oxidative stress and genotoxic damage in the lung and its failure to induce lung tumors under comparable experimental conditions. The proteome analysis showed a prominent role of apoptosis, counter-balanced by a positive regulation of the cell cycle aimed at replacing lost cells. In conclusion, our results suggest that, under basal conditions, mRNA undergoes a selective inactivation and post-transcriptional regulation resulting in de-coupling of transcriptome data and proteome data. However, this parallelism is re-established when the cell undergoes genotoxic damage."
730636,Huvinen et al. 2002,"Nasal cell micronuclei, cytology and clinical symptoms in stainless steel production workers exposed to chromium","The objective of the present study was to determine whether workers in stainless steel production with low exposure to various forms of chromium show an increase in micronucleated nasal cells or an excess of nasal symptoms or disease. Altogether, 48 workers employed in a stainless steel production chain were studied, 29 of them in the steel melting shop with exposure to hexavalent chromium (Cr(6+)), 14 in the sintering and crushing departments of the ferrochromium plant with exposure to trivalent chromium (Cr(3+)) and five in the mine with exposure to chromite ore (Cr(3+)). Thirty-nine workers from the cold rolling mill, with very low exposure to chromium, served as referents. All the subjects were never smokers with a minimum of 14 years employment in the same department. There were no significant differences between the exposure groups and the referents regarding the mean frequency of centromere-negative or centromere-positive micronuclei (studied by pancentromeric fluorescence in situ hybridization), nasal diseases and symptoms or mucociliary clearance of the nasal cavity. No statistically significant differences in the incidence of cell atypia or inflammatory cells were detected between the exposed workers and the reference group, except for an increase in lymphocytes among the chromite ore workers. Anterior rhinoscopy indicated slight inflammatory changes in nasal mucosa and secretion more often in the Cr(6+) and Cr(3+) groups than in the referents, the Cr(6+)-exposed workers showing more livid or oedemic epithelium. In conclusion, the stainless steel production workers, with low exposure to dusts or fumes containing hexavalent or trivalent chromium, did not show clinical changes in the nasal mucosa or an increase in nasal cell micronuclei or symptoms of nasal diseases, except for slight changes in the nasal epithelium and secretion.","Nasal cell micronuclei, cytology and clinical symptoms in stainless steel production workers exposed to chromium Abs: The objective of the present study was to determine whether workers in stainless steel production with low exposure to various forms of chromium show an increase in micronucleated nasal cells or an excess of nasal symptoms or disease. Altogether, 48 workers employed in a stainless steel production chain were studied, 29 of them in the steel melting shop with exposure to hexavalent chromium (Cr(6+)), 14 in the sintering and crushing departments of the ferrochromium plant with exposure to trivalent chromium (Cr(3+)) and five in the mine with exposure to chromite ore (Cr(3+)). Thirty-nine workers from the cold rolling mill, with very low exposure to chromium, served as referents. All the subjects were never smokers with a minimum of 14 years employment in the same department. There were no significant differences between the exposure groups and the referents regarding the mean frequency of centromere-negative or centromere-positive micronuclei (studied by pancentromeric fluorescence in situ hybridization), nasal diseases and symptoms or mucociliary clearance of the nasal cavity. No statistically significant differences in the incidence of cell atypia or inflammatory cells were detected between the exposed workers and the reference group, except for an increase in lymphocytes among the chromite ore workers. Anterior rhinoscopy indicated slight inflammatory changes in nasal mucosa and secretion more often in the Cr(6+) and Cr(3+) groups than in the referents, the Cr(6+)-exposed workers showing more livid or oedemic epithelium. In conclusion, the stainless steel production workers, with low exposure to dusts or fumes containing hexavalent or trivalent chromium, did not show clinical changes in the nasal mucosa or an increase in nasal cell micronuclei or symptoms of nasal diseases, except for slight changes in the nasal epithelium and secretion."
730635,Huang et al. 1999,Lipid peroxidation in workers exposed to hexavalent chromium,"The aim of this study was to investigate whether exposure to hexavalent chromium induces lipid peroxidation in human. This study involved 25 chrome-plating factory workers and a reference group of 28 control subjects. The whole-blood and urinary chromium concentrations were determined by graphite furnace atomic absorption spectrophotometry. Malondialdehyde (MDA), the product of lipid peroxidation, was determined by high-performance liquid chromatography, and the activities of protective enzymes were measured by ultraviolet-visible spectrophotometry. In the chrome-plating workers, the mean concentrations of chromium in blood and urine were 5.98 microg/L and 5.25 microg/g creatinine, respectively; the mean concentrations of MDA in blood and urine were 1.7 micromol/L and 2.24 micromol/g creatinine. The concentrations of both chromium and MDA in blood and urine were significantly higher in the chromium-exposed workers. The activities of superoxide dismutase (SOD), glutathione peroxidase (GPX), and catalase (CAT) were not markedly different between control and exposed workers. Data suggest that MDA may be used as a biomarker for occupational chromium exposure. Antioxidant enzymic activities are not a suitable marker for chromium exposure.","Lipid peroxidation in workers exposed to hexavalent chromium Abs: The aim of this study was to investigate whether exposure to hexavalent chromium induces lipid peroxidation in human. This study involved 25 chrome-plating factory workers and a reference group of 28 control subjects. The whole-blood and urinary chromium concentrations were determined by graphite furnace atomic absorption spectrophotometry. Malondialdehyde (MDA), the product of lipid peroxidation, was determined by high-performance liquid chromatography, and the activities of protective enzymes were measured by ultraviolet-visible spectrophotometry. In the chrome-plating workers, the mean concentrations of chromium in blood and urine were 5.98 microg/L and 5.25 microg/g creatinine, respectively; the mean concentrations of MDA in blood and urine were 1.7 micromol/L and 2.24 micromol/g creatinine. The concentrations of both chromium and MDA in blood and urine were significantly higher in the chromium-exposed workers. The activities of superoxide dismutase (SOD), glutathione peroxidase (GPX), and catalase (CAT) were not markedly different between control and exposed workers. Data suggest that MDA may be used as a biomarker for occupational chromium exposure. Antioxidant enzymic activities are not a suitable marker for chromium exposure."
730634,Hjollund et al. 2000,Male-mediated spontaneous abortion among spouses of stainless steel welders,"Male-mediated spontaneous abortion has never been documented for humans. The welding of stainless steel is associated with the pulmonary absorption of hexavalent chromium, which has genotoxic effects on germ cells in rodents. Clinical and early subclinical spontaneous abortions were examined among spouses of stainless-steel welders.<br /><br /> A cohort of first-pregnancy planners was recruited from members of the union of metal workers and 3 other trade unions. The cohort was followed for 6 menstrual cycles from the cessation of contraceptive use. Altogether, 280 pregnancies were conceived, of which 35 were detected by human chorionic gonadotrophic hormone analysis and did not survive to a clinically recognized pregnancy. Information on exposure was collected prospectively in relation to the outcome and was available for all cycles resulting in a pregnancy. Information on pregnancy outcome was collected for all 245 clinically recognized pregnancies.<br /><br /> Increased risk of spontaneous abortion was found for pregnancies with exposure to paternal stainless-steel welding (adjusted relative risk 3.5, 95% confidence interval 1.3-9.1). The results were consistent in analyses of both biochemically and clinically recognized abortions. There was no increased risk for spontaneous abortion in pregnancies with paternal exposure to the welding of metals other than stainless steel.<br /><br /> Male welding of stainless steel was associated with an increased risk of spontaneous abortion in spouses. A mutagenic effect of hexavalent chromium has been found previously in both somatic and germ cells, and the findings could be due to mutations in the male genome.","Male-mediated spontaneous abortion among spouses of stainless steel welders Abs: Male-mediated spontaneous abortion has never been documented for humans. The welding of stainless steel is associated with the pulmonary absorption of hexavalent chromium, which has genotoxic effects on germ cells in rodents. Clinical and early subclinical spontaneous abortions were examined among spouses of stainless-steel welders.<br /><br /> A cohort of first-pregnancy planners was recruited from members of the union of metal workers and 3 other trade unions. The cohort was followed for 6 menstrual cycles from the cessation of contraceptive use. Altogether, 280 pregnancies were conceived, of which 35 were detected by human chorionic gonadotrophic hormone analysis and did not survive to a clinically recognized pregnancy. Information on exposure was collected prospectively in relation to the outcome and was available for all cycles resulting in a pregnancy. Information on pregnancy outcome was collected for all 245 clinically recognized pregnancies.<br /><br /> Increased risk of spontaneous abortion was found for pregnancies with exposure to paternal stainless-steel welding (adjusted relative risk 3.5, 95% confidence interval 1.3-9.1). The results were consistent in analyses of both biochemically and clinically recognized abortions. There was no increased risk for spontaneous abortion in pregnancies with paternal exposure to the welding of metals other than stainless steel.<br /><br /> Male welding of stainless steel was associated with an increased risk of spontaneous abortion in spouses. A mutagenic effect of hexavalent chromium has been found previously in both somatic and germ cells, and the findings could be due to mutations in the male genome."
730633,Henshaw et al. 1999,Differentiation of normal human keratinocytes influences hexavalent chromium uptake and distribution and the ability of cells to withstand Cr(VI) cytotoxicity,"The degree of differentiation of normal human keratinocytes determines the biology of the cells to a large extent. We have previously documented that keratinocytes from different donors differ significantly in their ability to withstand hexavalent chromium [Cr(VI)]-induced cytotoxicity. Several factors may contribute to this differing donor sensitivity to Cr(VI). The aims of this study were to investigate to what extent keratinocyte differentiation might influence Cr(VI) uptake and the ability of cells to withstand Cr(VI)-induced cytotoxicity. Keratinocytes from different donors were cultured under identical conditions and exposed to Cr(VI) (as potassium dichromate) at different points during their maturation process. The degree of differentiation of the cells was assessed using a quantitative assay for involucrin and related to the Cr(VI) cytotoxicity experienced by the cells. Chromium content was measured in whole cell, cytosolic and particulate fractions. While proliferative keratinocytes exposed to Cr(VI) showed a high degree of cytotoxicity to dichromate exposure, the more differentiated cells showed significantly less cytotoxicity but a higher uptake of the metal ion into the cells. The relative percentage of cytosolic chromium was high in the proliferative cells and decreased as the cells matured, suggesting that differentiated cultures were binding most of the chromium to the particulate fraction. Total chromium also increased during differentiation. The use of the channel-blocking agent 4, 4'-diisothiocyanate-2-2'-stilbenedisulphonic acid confirmed the spatial differences of chromium accumulation in the phenotypically different cultures, in that it prevented Cr(VI) entry into the proliferative cells and attenuated dichromate cytotoxicity in these cultures, but had no effect on the Cr(VI) uptake in differentiated cells, nor did it reduce its cytotoxicity. These data support the hypothesis that the upper differentiated layers of the epidermis are able to offer considerable physical protection to the lower proliferative layers from chemical pro-oxidants.","Differentiation of normal human keratinocytes influences hexavalent chromium uptake and distribution and the ability of cells to withstand Cr(VI) cytotoxicity Abs: The degree of differentiation of normal human keratinocytes determines the biology of the cells to a large extent. We have previously documented that keratinocytes from different donors differ significantly in their ability to withstand hexavalent chromium [Cr(VI)]-induced cytotoxicity. Several factors may contribute to this differing donor sensitivity to Cr(VI). The aims of this study were to investigate to what extent keratinocyte differentiation might influence Cr(VI) uptake and the ability of cells to withstand Cr(VI)-induced cytotoxicity. Keratinocytes from different donors were cultured under identical conditions and exposed to Cr(VI) (as potassium dichromate) at different points during their maturation process. The degree of differentiation of the cells was assessed using a quantitative assay for involucrin and related to the Cr(VI) cytotoxicity experienced by the cells. Chromium content was measured in whole cell, cytosolic and particulate fractions. While proliferative keratinocytes exposed to Cr(VI) showed a high degree of cytotoxicity to dichromate exposure, the more differentiated cells showed significantly less cytotoxicity but a higher uptake of the metal ion into the cells. The relative percentage of cytosolic chromium was high in the proliferative cells and decreased as the cells matured, suggesting that differentiated cultures were binding most of the chromium to the particulate fraction. Total chromium also increased during differentiation. The use of the channel-blocking agent 4, 4'-diisothiocyanate-2-2'-stilbenedisulphonic acid confirmed the spatial differences of chromium accumulation in the phenotypically different cultures, in that it prevented Cr(VI) entry into the proliferative cells and attenuated dichromate cytotoxicity in these cultures, but had no effect on the Cr(VI) uptake in differentiated cells, nor did it reduce its cytotoxicity. These data support the hypothesis that the upper differentiated layers of the epidermis are able to offer considerable physical protection to the lower proliferative layers from chemical pro-oxidants."
730632,Hemmati et al. 2008,Comparison of the preventive effect of vitamin C and E on hexavalent chromium induced pulmonary fibrosis in rat,"Many studies have shown that hexavalent chromium (Cr(6+)) compounds cause variety of toxicity, such as carcinogenic effects and pulmonary fibrosis. The aim of this study was to investigate the effect of vitamins C and E on hexavalent chromium-induced lung fibrosis in animal model. Rats weighing 180-210 g were used during the study. The negative control group received a single dose of 0.2 ml intratracheal normal saline. Other groups were given single intratracheal instillation of 50 mg/kg sodium dichromate in saline vehicle and then treated with either vitamin C or E orally. Vit C group treated with 75 mg/kg/day vit C. Vit E group treated with 20 mg/kg/day vit E. Vit C+E group treated with 75 mg/kg/day vit C + 20 mg/kg/day vit E. Three weeks after such treatments animals were killed, lungs were removed for histology and biochemical investigation. Collagen and hydroxyproline content of lung tissue were determined using spectrophotometric methods. Hexavalent chromium caused marked alveolar thickening associated with fibroblasts and myofibroblasts proliferation and collagen production in interstitial tissue leading to pulmonary fibrosis. Administration of vitamins C and E reduced the fibrotic damage in lung tissue. The combination of vit E and C had more pronounced effect. From this study it can be concluded that co-administration of vit C & E may significantly diminish the toxic effects of hexavalent chromium on lung.","Comparison of the preventive effect of vitamin C and E on hexavalent chromium induced pulmonary fibrosis in rat Abs: Many studies have shown that hexavalent chromium (Cr(6+)) compounds cause variety of toxicity, such as carcinogenic effects and pulmonary fibrosis. The aim of this study was to investigate the effect of vitamins C and E on hexavalent chromium-induced lung fibrosis in animal model. Rats weighing 180-210 g were used during the study. The negative control group received a single dose of 0.2 ml intratracheal normal saline. Other groups were given single intratracheal instillation of 50 mg/kg sodium dichromate in saline vehicle and then treated with either vitamin C or E orally. Vit C group treated with 75 mg/kg/day vit C. Vit E group treated with 20 mg/kg/day vit E. Vit C+E group treated with 75 mg/kg/day vit C + 20 mg/kg/day vit E. Three weeks after such treatments animals were killed, lungs were removed for histology and biochemical investigation. Collagen and hydroxyproline content of lung tissue were determined using spectrophotometric methods. Hexavalent chromium caused marked alveolar thickening associated with fibroblasts and myofibroblasts proliferation and collagen production in interstitial tissue leading to pulmonary fibrosis. Administration of vitamins C and E reduced the fibrotic damage in lung tissue. The combination of vit E and C had more pronounced effect. From this study it can be concluded that co-administration of vit C & E may significantly diminish the toxic effects of hexavalent chromium on lung."
730630,Halasova et al. 2008,Chromosomal damage and polymorphisms of DNA repair genes XRCC1 and XRCC3 in workers exposed to chromium,"Welders, chronically exposed to hexavalent chromium, may exhibit disturbances in chromosomal integrity. Our study investigates chromosomal damage related to chromium exposure, considering the role of polymorphisms in relevant DNA repair genes.<br /><br /> 39 male welders exposed to chromium for 10.2+/-1.67 years and 31 male controls were assayed for structural chromosomal aberrations (conventional cytogenetic analysis). DNA repair gene polymorphisms were determined by Real-Time allelic discrimination assay.<br /><br /> Total chromosomal aberrations were moderately, but statistically not significant, higher in exposed individuals (1.96%) than in controls (1.55%). Chromosomal type breaks were almost two-fold higher in exposed than in control individuals. The highest frequency of total chromosomal aberrations was recorded in individuals with homozygous variant Gln/Gln cariers (2.14%) in XRCC1* Arg-399Gln and the lowest in those with the wild-type Arg/Arg cariers (1.33%). Polymorphisms in XRCC3 gene did not modulate the frequencies of CAs, CTAs and CSAs.<br /><br /> Understanding the effects of chromium on chromosomal integrity in relation to individual susceptibility may be a basis for preventive measures in working process.","Chromosomal damage and polymorphisms of DNA repair genes XRCC1 and XRCC3 in workers exposed to chromium Abs: Welders, chronically exposed to hexavalent chromium, may exhibit disturbances in chromosomal integrity. Our study investigates chromosomal damage related to chromium exposure, considering the role of polymorphisms in relevant DNA repair genes.<br /><br /> 39 male welders exposed to chromium for 10.2+/-1.67 years and 31 male controls were assayed for structural chromosomal aberrations (conventional cytogenetic analysis). DNA repair gene polymorphisms were determined by Real-Time allelic discrimination assay.<br /><br /> Total chromosomal aberrations were moderately, but statistically not significant, higher in exposed individuals (1.96%) than in controls (1.55%). Chromosomal type breaks were almost two-fold higher in exposed than in control individuals. The highest frequency of total chromosomal aberrations was recorded in individuals with homozygous variant Gln/Gln cariers (2.14%) in XRCC1* Arg-399Gln and the lowest in those with the wild-type Arg/Arg cariers (1.33%). Polymorphisms in XRCC3 gene did not modulate the frequencies of CAs, CTAs and CSAs.<br /><br /> Understanding the effects of chromium on chromosomal integrity in relation to individual susceptibility may be a basis for preventive measures in working process."
730629,Goulart et al. 2005,Lipoperoxidation products and thiol antioxidants in chromium exposed workers,"Hexavalent chromium is an established carcinogenic agent, which is not directly reactive with DNA. Its genotoxicity involves a reduction step, producing reactive oxygen species and radicals, and also lower valence forms which form stable complexes with intracellular macromolecules. The trivalent form of chromium may directly react with the genetic material and has also been shown to generate oxidative damage in vitro. To further evaluate the importance of in vivo oxidative DNA damage in the toxicity of each valence form, we conducted a comparative study on hexavalent and trivalent chromium-exposed workers (manual metal arc stainless steel welders and leather tanning workers), focusing on the total oxidative status by quantifying the level of lipoperoxidation products in urine. Thiol antioxidants are important in response to oxidative stress, and therefore, the concentration of glutathione and cysteine in peripheral blood lymphocytes was also determined. Chromium exposure was evaluated by quantifying total chromium in plasma and urine. Both groups had a significant increase in lipid peroxidation products expressed as malondialdehyde (MDA) in urine (tanners 1.42 +/- 0.61 micromol/g creatinine, welders 1.67 +/- 1.13 micromol/g creatinine versus controls 0.81 +/- 0.26 micromol/g creatinine, P < 0.005 in both cases) but only welders had a significant decrease in glutathione concentration in lymphocytes. There was a positive correlation between chromium in plasma and urinary MDA in welders, but not in tanners. This work is part of a larger study of which major results have been published previously including cytogenetics and DNA-protein cross-links in workers exposed to the two different forms of chromium. These results are compared with the results of oxidative damage from this study.","Lipoperoxidation products and thiol antioxidants in chromium exposed workers Abs: Hexavalent chromium is an established carcinogenic agent, which is not directly reactive with DNA. Its genotoxicity involves a reduction step, producing reactive oxygen species and radicals, and also lower valence forms which form stable complexes with intracellular macromolecules. The trivalent form of chromium may directly react with the genetic material and has also been shown to generate oxidative damage in vitro. To further evaluate the importance of in vivo oxidative DNA damage in the toxicity of each valence form, we conducted a comparative study on hexavalent and trivalent chromium-exposed workers (manual metal arc stainless steel welders and leather tanning workers), focusing on the total oxidative status by quantifying the level of lipoperoxidation products in urine. Thiol antioxidants are important in response to oxidative stress, and therefore, the concentration of glutathione and cysteine in peripheral blood lymphocytes was also determined. Chromium exposure was evaluated by quantifying total chromium in plasma and urine. Both groups had a significant increase in lipid peroxidation products expressed as malondialdehyde (MDA) in urine (tanners 1.42 +/- 0.61 micromol/g creatinine, welders 1.67 +/- 1.13 micromol/g creatinine versus controls 0.81 +/- 0.26 micromol/g creatinine, P < 0.005 in both cases) but only welders had a significant decrease in glutathione concentration in lymphocytes. There was a positive correlation between chromium in plasma and urinary MDA in welders, but not in tanners. This work is part of a larger study of which major results have been published previously including cytogenetics and DNA-protein cross-links in workers exposed to the two different forms of chromium. These results are compared with the results of oxidative damage from this study."
730628,Elsaieed and  Nada 2002,Teratogenicity of hexavalent chromium in rats and the beneficial role of ginseng,,Teratogenicity of hexavalent chromium in rats and the beneficial role of ginseng Abs: 
730626,D'Agostini et al. 2002,Induction of apoptosis in the lung but not in the liver of rats receiving intra-tracheal instillations of chromium(VI),"Several studies have shown that hexavalent chromium [Cr(VI)] induces apoptosis in a variety of in vitro test systems. We instilled intra-tracheally either saline or sodium dichromate (0.25 mg/kg body weight), for three consecutive days, to Sprague-Dawley rats. TUNEL analyses showed a marked increase of the apoptotic index in both bronchial epithelium and lung parenchyma of Cr(VI)-treated rats, but no effect was detected in their liver. In parallel, the expression of 13 out of 18 apoptosis-related genes, evaluated by cDNA array analysis, was significantly enhanced in rat lung. The overexpressed genes included c-Jun N-terminal kinases 1, 2 and 3, bcl-x, bcl-2-associated death promoter and bcl-2-related ovarian killer protein, caspases 1, 3 and 6, DNase I precursor, DNA topoisomerases I and II alpha, and poly(ADP-ribose) polymerase. The enhancement of p53 expression in the lung was borderline to statistical significance. Expressions of bcl-2, bax-alpha, mdm2 and DNA topoisomerase IIB were not enhanced to a significant extent in lung. No induction of gene expression was observed in rat liver. RT-PCR analyses confirmed that Cr(VI) enhances the expression of c-Jun N-terminal kinase 1, caspase 6, and DNase I precursor but not that of bcl-2 in lung, while none of these genes was overexpressed in the liver of Cr(VI)-treated rats. The lack of stimulation of apoptosis in the liver parallels the failure of Cr(VI) to produce genotoxic damage, as we previously observed under identical experimental conditions. These negative findings may be ascribed to reduction of Cr(VI) to Cr(III) when traveling from the respiratory tract to the liver. On the other hand, induction of apoptosis in the respiratory tract parallels the occurrence of genotoxic effects and oxidative DNA damage produced by Cr(VI) in the same tissue. As previously shown in another laboratory, Cr(VI) did not induce lung tumors after 30 months of administration of the same daily dose. Therefore, apoptosis is likely to provide a protective mechanism at a post-genotoxic stage of Cr(VI) carcinogenesis.","Induction of apoptosis in the lung but not in the liver of rats receiving intra-tracheal instillations of chromium(VI) Abs: Several studies have shown that hexavalent chromium [Cr(VI)] induces apoptosis in a variety of in vitro test systems. We instilled intra-tracheally either saline or sodium dichromate (0.25 mg/kg body weight), for three consecutive days, to Sprague-Dawley rats. TUNEL analyses showed a marked increase of the apoptotic index in both bronchial epithelium and lung parenchyma of Cr(VI)-treated rats, but no effect was detected in their liver. In parallel, the expression of 13 out of 18 apoptosis-related genes, evaluated by cDNA array analysis, was significantly enhanced in rat lung. The overexpressed genes included c-Jun N-terminal kinases 1, 2 and 3, bcl-x, bcl-2-associated death promoter and bcl-2-related ovarian killer protein, caspases 1, 3 and 6, DNase I precursor, DNA topoisomerases I and II alpha, and poly(ADP-ribose) polymerase. The enhancement of p53 expression in the lung was borderline to statistical significance. Expressions of bcl-2, bax-alpha, mdm2 and DNA topoisomerase IIB were not enhanced to a significant extent in lung. No induction of gene expression was observed in rat liver. RT-PCR analyses confirmed that Cr(VI) enhances the expression of c-Jun N-terminal kinase 1, caspase 6, and DNase I precursor but not that of bcl-2 in lung, while none of these genes was overexpressed in the liver of Cr(VI)-treated rats. The lack of stimulation of apoptosis in the liver parallels the failure of Cr(VI) to produce genotoxic damage, as we previously observed under identical experimental conditions. These negative findings may be ascribed to reduction of Cr(VI) to Cr(III) when traveling from the respiratory tract to the liver. On the other hand, induction of apoptosis in the respiratory tract parallels the occurrence of genotoxic effects and oxidative DNA damage produced by Cr(VI) in the same tissue. As previously shown in another laboratory, Cr(VI) did not induce lung tumors after 30 months of administration of the same daily dose. Therefore, apoptosis is likely to provide a protective mechanism at a post-genotoxic stage of Cr(VI) carcinogenesis."
730623,Cohen et al. 2003,Impact of coexposure to ozone on the carcinogenic potential of inhaled chromium. 1. Effects on retention and on extra- and intracellular distribution,"A health hazard to welders is development of lung cancer. It is believed that this is likely due, in part, to the presence in welding fumes of several hexavalent chromium (Cr[VI]) species, whose solubility depends primarily on which process (i.e., manual metal arc verus metal-inert gas) is used. However, inhalation of Cr alone is uncommon in this setting. Thus, an examination of potential contributions from other coinhalants in creating or enhancing conditions whereby inhaled fume-associated Cr (primarily the insoluble forms) may initiate cancer is critical to increasing our understanding and preventing this particular occupational disease. One major chemical species formed and released during welding is ozone (O3). Though implications of adverse pulmonary effects from individual exposure to Cr or O3 have been investigated, those from simultaneous exposure are unclear. To begin to address whether the carcinogenic potential of insoluble Cr[VI] agents might be enhanced in hosts inhaling mixtures of Cr and O3 versus Cr alone, analyses of total lung Cr burden, Cr retention in lung epithelium and interstitium, and potential shifts in lung cell distribution of Cr from the cytoplasm to nuclei were undertaken in F-344 rats exposed nose-only (5 h/d, 5 d/wk for up to 48 wk) to an extrapolated occupationally relevant level of Cr (360 micrograms Cr/m3 as calcium chromate) alone and in combination with 0.3 ppm O3. Overall, there was only a nominal effect from O3 on Cr retention or on distribution of Cr particles among extracellular sites and within lung cells. However, there were O3-related effects upon mechanisms for clearing the Cr from the deep lung, specifically at the levels of particle uptake and postphagocytic/endocytic processing by macrophages. This O3 exposure-related shift in normal pulmonary clearance might potentially increase the health risk in workers exposed to other insoluble or poorly soluble carcinogenic Cr compounds.","Impact of coexposure to ozone on the carcinogenic potential of inhaled chromium. 1. Effects on retention and on extra- and intracellular distribution Abs: A health hazard to welders is development of lung cancer. It is believed that this is likely due, in part, to the presence in welding fumes of several hexavalent chromium (Cr[VI]) species, whose solubility depends primarily on which process (i.e., manual metal arc verus metal-inert gas) is used. However, inhalation of Cr alone is uncommon in this setting. Thus, an examination of potential contributions from other coinhalants in creating or enhancing conditions whereby inhaled fume-associated Cr (primarily the insoluble forms) may initiate cancer is critical to increasing our understanding and preventing this particular occupational disease. One major chemical species formed and released during welding is ozone (O3). Though implications of adverse pulmonary effects from individual exposure to Cr or O3 have been investigated, those from simultaneous exposure are unclear. To begin to address whether the carcinogenic potential of insoluble Cr[VI] agents might be enhanced in hosts inhaling mixtures of Cr and O3 versus Cr alone, analyses of total lung Cr burden, Cr retention in lung epithelium and interstitium, and potential shifts in lung cell distribution of Cr from the cytoplasm to nuclei were undertaken in F-344 rats exposed nose-only (5 h/d, 5 d/wk for up to 48 wk) to an extrapolated occupationally relevant level of Cr (360 micrograms Cr/m3 as calcium chromate) alone and in combination with 0.3 ppm O3. Overall, there was only a nominal effect from O3 on Cr retention or on distribution of Cr particles among extracellular sites and within lung cells. However, there were O3-related effects upon mechanisms for clearing the Cr from the deep lung, specifically at the levels of particle uptake and postphagocytic/endocytic processing by macrophages. This O3 exposure-related shift in normal pulmonary clearance might potentially increase the health risk in workers exposed to other insoluble or poorly soluble carcinogenic Cr compounds."
730622,Clottens et al. 1996,Assessment of the ear swelling test and the local lymph node assay in hamsters,"In a hamster model, we compared contact sensitivity to the metal salt, potassium dichromate, to that of oxazolone, a well-known strong sensitizing agent. Using the ear swelling test, originally developed in mice, no significant differences could be observed between animals treated with potassium dichromate and controls, although oxazolone-treated animals showed a significant increase in ear thickness compared to controls. These observations were confirmed using the local lymph node assay (LLNA) where oxazolone proved to be a strong sensitizing agent, and potassium dichromate only resulted in a weak response. When the draining auricular lymph nodes were compared with the inguinal lymph nodes in the LLNA, more pronounced effects were obtained with the auricular lymph nodes. This study indicates that, also in hamsters, the LLNA is a feasible sensitization test system.","Assessment of the ear swelling test and the local lymph node assay in hamsters Abs: In a hamster model, we compared contact sensitivity to the metal salt, potassium dichromate, to that of oxazolone, a well-known strong sensitizing agent. Using the ear swelling test, originally developed in mice, no significant differences could be observed between animals treated with potassium dichromate and controls, although oxazolone-treated animals showed a significant increase in ear thickness compared to controls. These observations were confirmed using the local lymph node assay (LLNA) where oxazolone proved to be a strong sensitizing agent, and potassium dichromate only resulted in a weak response. When the draining auricular lymph nodes were compared with the inguinal lymph nodes in the LLNA, more pronounced effects were obtained with the auricular lymph nodes. This study indicates that, also in hamsters, the LLNA is a feasible sensitization test system."
730621,Cheng et al. 2000,Chromium(VI)-induced mutagenesis in the lungs of big blue transgenic mice,"The mutagenic activity of the hexavalent chromium [Cr(VI)] compound potassium dichromate was examined in the Big Blue transgenic mouse lung, the target organ for Cr(VI) carcinogenesis in humans. Mice were exposed to Cr(VI) by intratracheal instillation of a potassium dichromate (K2Cr2O7) solution. Analysis of the deposition of Cr in mouse lungs revealed that the procedure reproducibly resulted in about 5% retention of the Cr in the lung. Lower but measurable levels were detected in kidney and liver. We found a dose-dependent and time-dependent increase in the mutant frequency in the mouse lung. A significant elevation of the mutant frequency above the spontaneous background was observed two weeks after Cr(VI) intratracheal instillation and at doses above 3 mg/kg. Depletion of tissue glutathione (GSH) levels by buthionine sulfoximine (BSO) before Cr(VI) treatment led to a decrease in the Cr(VI)-induced mutant frequency, compared to that in the animals with normal GSH levels, suggesting a role for GSH in the generation of reactive intermediates during the intracellular reduction of Cr(VI). Sequence analysis for the Cr(VI)-induced mutants revealed a similarity to the spontaneous mutational spectrum observed in mouse lungs, consistent with the generation of oxidative-type DNA damage by Cr(VI). These results demonstrate that Cr(VI) is mutagenic in mouse lung, the target organ for human carcinogenesis.","Chromium(VI)-induced mutagenesis in the lungs of big blue transgenic mice Abs: The mutagenic activity of the hexavalent chromium [Cr(VI)] compound potassium dichromate was examined in the Big Blue transgenic mouse lung, the target organ for Cr(VI) carcinogenesis in humans. Mice were exposed to Cr(VI) by intratracheal instillation of a potassium dichromate (K2Cr2O7) solution. Analysis of the deposition of Cr in mouse lungs revealed that the procedure reproducibly resulted in about 5% retention of the Cr in the lung. Lower but measurable levels were detected in kidney and liver. We found a dose-dependent and time-dependent increase in the mutant frequency in the mouse lung. A significant elevation of the mutant frequency above the spontaneous background was observed two weeks after Cr(VI) intratracheal instillation and at doses above 3 mg/kg. Depletion of tissue glutathione (GSH) levels by buthionine sulfoximine (BSO) before Cr(VI) treatment led to a decrease in the Cr(VI)-induced mutant frequency, compared to that in the animals with normal GSH levels, suggesting a role for GSH in the generation of reactive intermediates during the intracellular reduction of Cr(VI). Sequence analysis for the Cr(VI)-induced mutants revealed a similarity to the spontaneous mutational spectrum observed in mouse lungs, consistent with the generation of oxidative-type DNA damage by Cr(VI). These results demonstrate that Cr(VI) is mutagenic in mouse lung, the target organ for human carcinogenesis."
730620,Cheng et al. 1998,"Analysis of repair and mutagenesis of chromium-induced DNA damage in yeast, mammalian cells, and transgenic mice","Chromium (Cr) is a widespread environmental contaminant and a known human carcinogen. We have used shuttle vector systems in yeast, mammalian cells, and transgenic mice to characterize the mutational specificity and premutational DNA damage induced by Cr(VI) and its reduction intermediates in order to elucidate the mechanism by which Cr induces mutations. In the yeast system, treatment of vector-containing cells with Cr(VI) results in a dose-dependent increase in mutations in the SUP4-o target gene of the vector; mutagenesis is enhanced in an apn-1 yeast mutant, deficient in the capacity to repair oxidative-type DNA damage. In vector-containing mammalian cells, treatment with Cr(VI) also results in a dose-dependent increase in mutations in the vector target gene supF. The Cr-induced mutations in supF occurred mostly at G:C base pairs and were widely distributed across the gene, a pattern similar to those observed with ionizing radiation or hydrogen peroxide. These results support the hypothesis that Cr(VI)-induced oxidative-type DNA damage is responsible for Cr mutagenesis in the cell. Recently these studies were extended into the Big Blue transgenic mouse system in which Cr-induced mutagenesis was observed in the lung, the target organ for Cr carcinogenesis in humans. Analysis of the spectrum of these mutations will test whether Cr mutagenesis occurs by similar mechanisms in the intact animal as in cell culture systems and yeast.","Analysis of repair and mutagenesis of chromium-induced DNA damage in yeast, mammalian cells, and transgenic mice Abs: Chromium (Cr) is a widespread environmental contaminant and a known human carcinogen. We have used shuttle vector systems in yeast, mammalian cells, and transgenic mice to characterize the mutational specificity and premutational DNA damage induced by Cr(VI) and its reduction intermediates in order to elucidate the mechanism by which Cr induces mutations. In the yeast system, treatment of vector-containing cells with Cr(VI) results in a dose-dependent increase in mutations in the SUP4-o target gene of the vector; mutagenesis is enhanced in an apn-1 yeast mutant, deficient in the capacity to repair oxidative-type DNA damage. In vector-containing mammalian cells, treatment with Cr(VI) also results in a dose-dependent increase in mutations in the vector target gene supF. The Cr-induced mutations in supF occurred mostly at G:C base pairs and were widely distributed across the gene, a pattern similar to those observed with ionizing radiation or hydrogen peroxide. These results support the hypothesis that Cr(VI)-induced oxidative-type DNA damage is responsible for Cr mutagenesis in the cell. Recently these studies were extended into the Big Blue transgenic mouse system in which Cr-induced mutagenesis was observed in the lung, the target organ for Cr carcinogenesis in humans. Analysis of the spectrum of these mutations will test whether Cr mutagenesis occurs by similar mechanisms in the intact animal as in cell culture systems and yeast."
730619,Caglieri et al. 2006,The effect of inhaled chromium on different exhaled breath condensate biomarkers among chrome-plating workers,"Chromium is corrosive, cytotoxic, and carcinogenic for humans and can induce acute and chronic lung tissue toxicity. The aim of this study was to investigate Cr levels in exhaled breath condensate (EBC) of workers exposed to Cr(VI) and to assess their relationship with biochemical changes in the airways by analyzing EBC biomarkers of oxidative stress, namely, hydrogen peroxide (H2O2) and malondialdehyde (MDA). EBC samples were collected from 24 chrome-plating workers employed in a chrome-plating plant both before and after the Friday work shift and before the work shift on the following Monday. Cr-EBC levels increased from the beginning (5.3 microg/L) to the end of Friday (6.4 microg/L) but were considerably lower on Monday morning (2.8 microg/L). A similar trend was observed for H2O2-EBC levels (which increased from 0.36 microM to 0.59 microM on Friday and were 0.19 microM on Monday morning) and MDA-EBC levels (which increased from 8.2 nM to 9.7 nM on Friday and were 6.6 nM on Monday). Cr-EBC levels correlated with those of H2O2-EBC (r = 0.54, p < 0.01) and MDA-EBC (r = 0.59, p < 0.01), as well as with urinary Cr levels (r = 0.25, p < 0.05). The results of this study demonstrate that EBC is a suitable matrix that can be used to investigate both Cr levels and biomarkers of free radical production sampling the epithelial-lining fluid of workers exposed to Cr(VI).","The effect of inhaled chromium on different exhaled breath condensate biomarkers among chrome-plating workers Abs: Chromium is corrosive, cytotoxic, and carcinogenic for humans and can induce acute and chronic lung tissue toxicity. The aim of this study was to investigate Cr levels in exhaled breath condensate (EBC) of workers exposed to Cr(VI) and to assess their relationship with biochemical changes in the airways by analyzing EBC biomarkers of oxidative stress, namely, hydrogen peroxide (H2O2) and malondialdehyde (MDA). EBC samples were collected from 24 chrome-plating workers employed in a chrome-plating plant both before and after the Friday work shift and before the work shift on the following Monday. Cr-EBC levels increased from the beginning (5.3 microg/L) to the end of Friday (6.4 microg/L) but were considerably lower on Monday morning (2.8 microg/L). A similar trend was observed for H2O2-EBC levels (which increased from 0.36 microM to 0.59 microM on Friday and were 0.19 microM on Monday morning) and MDA-EBC levels (which increased from 8.2 nM to 9.7 nM on Friday and were 6.6 nM on Monday). Cr-EBC levels correlated with those of H2O2-EBC (r = 0.54, p < 0.01) and MDA-EBC (r = 0.59, p < 0.01), as well as with urinary Cr levels (r = 0.25, p < 0.05). The results of this study demonstrate that EBC is a suitable matrix that can be used to investigate both Cr levels and biomarkers of free radical production sampling the epithelial-lining fluid of workers exposed to Cr(VI)."
730617,Beaver et al. 2009,"Lung inflammation, injury, and proliferative response after repetitive particulate hexavalent chromium exposure","Chronic inflammation is implicated in the development of several human cancers, including lung cancer. Certain particulate hexavalent chromium [Cr(VI)] compounds are well-documented human respiratory carcinogens that release genotoxic soluble chromate and are associated with fibrosis, fibrosarcomas, adenocarcinomas, and squamous cell carcinomas of the lung. Despite this, little is known about the pathologic injury and immune responses after repetitive exposure to particulate chromates.<br /><br /> In this study we investigated the lung injury, inflammation, proliferation, and survival signaling responses after repetitive exposure to particulate chromate.<br /><br /> BALB/c mice were repetitively treated with particulate basic zinc chromate or saline using an intranasal exposure regimen. We assessed lungs for Cr(VI)-induced changes by bronchoalveolar lavage, histologic examination, and immunohistochemistry.<br /><br /> Single exposure to Cr(VI) resulted in inflammation of lung tissue that persists for up to 21 days. Repetitive Cr(VI) exposure induced a neutrophilic inflammatory airway response 24 hr after each treatment. Neutrophils were subsequently replaced by increasing numbers of macrophages by 5 days after treatment. Repetitive Cr(VI) exposure induced chronic peribronchial inflammation with alveolar and interstitial pneumonitis dominated by lymphocytes and macrophages. Moreover, chronic toxic mucosal injury was observed and accompanied by increased airway pro-matrix metalloprotease-9. Injury and inflammation correlated with airways becoming immunoreactive for phosphorylation of the survival signaling protein Akt and the proliferation marker Ki-67. We observed a reactive proliferative response in epithelial cells lining airways of chromate-exposed animals.<br /><br /> These data illustrate that repetitive exposure to particulate chromate induces chronic injury and an inflammatory microenvironment that may promote Cr(VI) carcinogenesis.","Lung inflammation, injury, and proliferative response after repetitive particulate hexavalent chromium exposure Abs: Chronic inflammation is implicated in the development of several human cancers, including lung cancer. Certain particulate hexavalent chromium [Cr(VI)] compounds are well-documented human respiratory carcinogens that release genotoxic soluble chromate and are associated with fibrosis, fibrosarcomas, adenocarcinomas, and squamous cell carcinomas of the lung. Despite this, little is known about the pathologic injury and immune responses after repetitive exposure to particulate chromates.<br /><br /> In this study we investigated the lung injury, inflammation, proliferation, and survival signaling responses after repetitive exposure to particulate chromate.<br /><br /> BALB/c mice were repetitively treated with particulate basic zinc chromate or saline using an intranasal exposure regimen. We assessed lungs for Cr(VI)-induced changes by bronchoalveolar lavage, histologic examination, and immunohistochemistry.<br /><br /> Single exposure to Cr(VI) resulted in inflammation of lung tissue that persists for up to 21 days. Repetitive Cr(VI) exposure induced a neutrophilic inflammatory airway response 24 hr after each treatment. Neutrophils were subsequently replaced by increasing numbers of macrophages by 5 days after treatment. Repetitive Cr(VI) exposure induced chronic peribronchial inflammation with alveolar and interstitial pneumonitis dominated by lymphocytes and macrophages. Moreover, chronic toxic mucosal injury was observed and accompanied by increased airway pro-matrix metalloprotease-9. Injury and inflammation correlated with airways becoming immunoreactive for phosphorylation of the survival signaling protein Akt and the proliferation marker Ki-67. We observed a reactive proliferative response in epithelial cells lining airways of chromate-exposed animals.<br /><br /> These data illustrate that repetitive exposure to particulate chromate induces chronic injury and an inflammatory microenvironment that may promote Cr(VI) carcinogenesis."
730616,Beaver et al. 2009,"Lung injury, inflammation and Akt signaling following inhalation of particulate hexavalent chromium","Certain particulate hexavalent chromium [Cr(VI)] compounds are human respiratory carcinogens that release genotoxic soluble chromate, and are associated with fibrosis, fibrosarcomas, adenocarcinomas and squamous cell carcinomas of the lung. We postulate that inflammatory processes and mediators may contribute to the etiology of Cr(VI) carcinogenesis, however the immediate (0-24 h) pathologic injury and immune responses after exposure to particulate chromates have not been adequately investigated. Our aim was to determine the nature of the lung injury, inflammatory response, and survival signaling responses following intranasal exposure of BALB/c mice to particulate basic zinc chromate. Factors associated with lung injury, inflammation and survival signaling were measured in airway lavage fluid and in lung tissue. A single chromate exposure induced an acute immune response in the lung, characterized by a rapid and significant increase in IL-6 and GRO-alpha levels, an influx of neutrophils, and a decline in macrophages in lung airways. Histological examination of lung tissue in animals challenged with a single chromate exposure revealed an increase in bronchiolar cell apoptosis and mucosal injury. Furthermore, chromate exposure induced injury and inflammation that progressed to alveolar and interstitial pneumonitis. Finally, a single Cr(VI) challenge resulted in a rapid and persistent increase in the number of airways immunoreactive for phosphorylation of the survival signaling protein Akt, on serine 473. These data illustrate that chromate induces both survival signaling and an inflammatory response in the lung, which we postulate may contribute to early oncogenesis.","Lung injury, inflammation and Akt signaling following inhalation of particulate hexavalent chromium Abs: Certain particulate hexavalent chromium [Cr(VI)] compounds are human respiratory carcinogens that release genotoxic soluble chromate, and are associated with fibrosis, fibrosarcomas, adenocarcinomas and squamous cell carcinomas of the lung. We postulate that inflammatory processes and mediators may contribute to the etiology of Cr(VI) carcinogenesis, however the immediate (0-24 h) pathologic injury and immune responses after exposure to particulate chromates have not been adequately investigated. Our aim was to determine the nature of the lung injury, inflammatory response, and survival signaling responses following intranasal exposure of BALB/c mice to particulate basic zinc chromate. Factors associated with lung injury, inflammation and survival signaling were measured in airway lavage fluid and in lung tissue. A single chromate exposure induced an acute immune response in the lung, characterized by a rapid and significant increase in IL-6 and GRO-alpha levels, an influx of neutrophils, and a decline in macrophages in lung airways. Histological examination of lung tissue in animals challenged with a single chromate exposure revealed an increase in bronchiolar cell apoptosis and mucosal injury. Furthermore, chromate exposure induced injury and inflammation that progressed to alveolar and interstitial pneumonitis. Finally, a single Cr(VI) challenge resulted in a rapid and persistent increase in the number of airways immunoreactive for phosphorylation of the survival signaling protein Akt, on serine 473. These data illustrate that chromate induces both survival signaling and an inflammatory response in the lung, which we postulate may contribute to early oncogenesis."
730615,Balansky et al. 2000,Less than additive interaction between cigarette smoke and chromium(VI) in inducing clastogenic damage in rodents,"A combination of tobacco smoking with certain agents has been shown to exert synergistic carcinogenic effects. On the other hand, antagonism betweeen smoke and other pulmonary carcinogens has also been documented by both epidemiological and experimental data. In spite of a very large number of studies carried out for decades in workers exposed to hexavalent chromium, the influence of smoking habits on lung carcinogenesis induced by this metal has not been clarified. For this reason, we performed two studies evaluating clastogenic effects in rodents. In the first one, BDF(1) mice were exposed whole-body to mainstream cigarette smoke for 5 days and, on the last day, they received an i.p. injection of potassium dichromate. In the second study, Sprague-Dawley rats were exposed whole-body to environmental cigarette smoke for 18 consecutive days and for the same period of time they received daily intra-tracheal instillations of sodium dichromate. Individually, the two hexavalent chromium salts and cigarette smoke, either mainstream or environmental, enhanced the frequency of micronuclei in bone marrow polychromatic erythrocytes of both mice and rats. Moreover, individual exposure to either environmental cigarette smoke or sodium dichromate enhanced the frequency of micronuclei and multiple nuclei in pulmonary alveolar macrophages of rats. In both studies, combined exposure to cigarette smoke and hexavalent chromium produced less than additive clastogenic effects. These results are consistent with our previous data, showing that hexavalent chromium and either benzo[a]pyrene or cigarette smoke condensate behave antagonistically in in vitro mutagenicity test systems and that the chromium reducing capacity of human pulmonary alveolar macrophages and peripheral lung parenchyma is enhanced in smokers. Taken together, in the absence of any epidemiological evidence, these findings rule out any occurrence of synergism between cigarette smoke and hexavalent chromium, at least in certain stages of the carcinogenesis process.","Less than additive interaction between cigarette smoke and chromium(VI) in inducing clastogenic damage in rodents Abs: A combination of tobacco smoking with certain agents has been shown to exert synergistic carcinogenic effects. On the other hand, antagonism betweeen smoke and other pulmonary carcinogens has also been documented by both epidemiological and experimental data. In spite of a very large number of studies carried out for decades in workers exposed to hexavalent chromium, the influence of smoking habits on lung carcinogenesis induced by this metal has not been clarified. For this reason, we performed two studies evaluating clastogenic effects in rodents. In the first one, BDF(1) mice were exposed whole-body to mainstream cigarette smoke for 5 days and, on the last day, they received an i.p. injection of potassium dichromate. In the second study, Sprague-Dawley rats were exposed whole-body to environmental cigarette smoke for 18 consecutive days and for the same period of time they received daily intra-tracheal instillations of sodium dichromate. Individually, the two hexavalent chromium salts and cigarette smoke, either mainstream or environmental, enhanced the frequency of micronuclei in bone marrow polychromatic erythrocytes of both mice and rats. Moreover, individual exposure to either environmental cigarette smoke or sodium dichromate enhanced the frequency of micronuclei and multiple nuclei in pulmonary alveolar macrophages of rats. In both studies, combined exposure to cigarette smoke and hexavalent chromium produced less than additive clastogenic effects. These results are consistent with our previous data, showing that hexavalent chromium and either benzo[a]pyrene or cigarette smoke condensate behave antagonistically in in vitro mutagenicity test systems and that the chromium reducing capacity of human pulmonary alveolar macrophages and peripheral lung parenchyma is enhanced in smokers. Taken together, in the absence of any epidemiological evidence, these findings rule out any occurrence of synergism between cigarette smoke and hexavalent chromium, at least in certain stages of the carcinogenesis process."
730614,Balachandar et al. 2010,"Evaluation of the genetic alterations in direct and indirect exposures of hexavalent chromium [Cr(VI)] in leather tanning industry workers North Arcot District, South India","The focal aim of the present study was to identify the genetic alterations occurring in the tannery workers and surrounding inhabitants chronically exposed to hexavalent chromium [Cr(VI)].<br /><br /> A total of 108 samples which includes 72 exposed subjects [36 directly exposed (DE) subjects and 36 indirectly exposed (IE) subjects] and 36 controls were recruited for this study. The exposed subjects and controls were selected based on the Cr level present in air and their urine. Directly exposed subjects were categorized based on their work duration in the tannery industries, whereas the indirectly exposed subjects were categorized based on their year of residence in the place adjacent to tannery industries for more than 3 decades. Controls were normal and healthy. Age was matched for the exposed subjects and controls. The exposed subjects as well as the controls were categorized based on their age (group I, <40 years; group II, >41 years). Cell cultures were established from blood samples (5 ml from each subject) collected from the subjects (exposed subjects and controls) after obtaining informed consent. G-banding (Giemsa staining) of the cultures, micronucleus (MN) assay and comet assay were used to identify the genetic alterations of individuals exposed to Cr(VI) in comparison with the controls.<br /><br /> A higher degree of total CA [12 ± 8.49 (21-25 years)] and MN [18.69 ± 7.39 (11-15 years)] was found in DE subjects compared to other groups. In IE subjects, elevated levels of CA [5.67 ± 1.15 (51-60 years)] and MN [25 ± 9.89 (71-80 years)] were observed. As expected, controls exhibited minimal number of alterations. The overall CA frequency due to Cr exposure was significantly different from that of the controls for both chromatid and chromosome type aberrations (P < 0.05 by ANOVA). The MN/1,000 binucleated cells were significantly increased (P < 0.05) in the peripheral lymphocytes of DE and IE subjects in comparison with controls. The mean tail length of comet assay for DE, IE and controls were analyzed. The mean tail length of DE subjects [4.21 (3.21-10.98)] was higher compared to that of IE subjects [3.98 (2.98-11.27)] and controls [3.01 (2.68-9.40)].<br /><br /> In conclusion, this work shows a clear genotoxic effect associated with chromium exposure, both directly and indirectly. Our result reinforces the higher sensitivity of cytogenetic assays for the biomonitoring of occupationally exposed populations. There is a strong need to educate those who work with potentially hazardous heavy about its adverse effects and highlight the importance of using protective measures.","Evaluation of the genetic alterations in direct and indirect exposures of hexavalent chromium [Cr(VI)] in leather tanning industry workers North Arcot District, South India Abs: The focal aim of the present study was to identify the genetic alterations occurring in the tannery workers and surrounding inhabitants chronically exposed to hexavalent chromium [Cr(VI)].<br /><br /> A total of 108 samples which includes 72 exposed subjects [36 directly exposed (DE) subjects and 36 indirectly exposed (IE) subjects] and 36 controls were recruited for this study. The exposed subjects and controls were selected based on the Cr level present in air and their urine. Directly exposed subjects were categorized based on their work duration in the tannery industries, whereas the indirectly exposed subjects were categorized based on their year of residence in the place adjacent to tannery industries for more than 3 decades. Controls were normal and healthy. Age was matched for the exposed subjects and controls. The exposed subjects as well as the controls were categorized based on their age (group I, <40 years; group II, >41 years). Cell cultures were established from blood samples (5 ml from each subject) collected from the subjects (exposed subjects and controls) after obtaining informed consent. G-banding (Giemsa staining) of the cultures, micronucleus (MN) assay and comet assay were used to identify the genetic alterations of individuals exposed to Cr(VI) in comparison with the controls.<br /><br /> A higher degree of total CA [12 ± 8.49 (21-25 years)] and MN [18.69 ± 7.39 (11-15 years)] was found in DE subjects compared to other groups. In IE subjects, elevated levels of CA [5.67 ± 1.15 (51-60 years)] and MN [25 ± 9.89 (71-80 years)] were observed. As expected, controls exhibited minimal number of alterations. The overall CA frequency due to Cr exposure was significantly different from that of the controls for both chromatid and chromosome type aberrations (P < 0.05 by ANOVA). The MN/1,000 binucleated cells were significantly increased (P < 0.05) in the peripheral lymphocytes of DE and IE subjects in comparison with controls. The mean tail length of comet assay for DE, IE and controls were analyzed. The mean tail length of DE subjects [4.21 (3.21-10.98)] was higher compared to that of IE subjects [3.98 (2.98-11.27)] and controls [3.01 (2.68-9.40)].<br /><br /> In conclusion, this work shows a clear genotoxic effect associated with chromium exposure, both directly and indirectly. Our result reinforces the higher sensitivity of cytogenetic assays for the biomonitoring of occupationally exposed populations. There is a strong need to educate those who work with potentially hazardous heavy about its adverse effects and highlight the importance of using protective measures."
730613,Aoyama et al. 2007,Contact sensitizer potassium dichromate alters lymphocyte populations in draining lymph nodes and blood in mice,"ABSTRACT Chromium is a common human contact allergen, but it is not known whether chromates cause contact hypersensitivity by immunological mechanisms similar to those induced by strong haptens. To understand the immunological events of contact hypersensitivity to chromates, we investigated whether and how chromate sensitization alters lymphocyte subsets in draining lymph nodes (DLNs), blood, and spleens in mice. BALB/c mice were sensitized by painting their ears with 0.5% potassium dichromate or vehicle alone on 3 consecutive days. Flow cytometric analysis of lymphocyte surface antigens showed that the chromate exposure significantly increased the percentage of B cells and decreased the percentages of T cells in the DLNs. This was accompanied by a relative increase in T cells and a relative decrease in B cells in peripheral blood. In contrast to the chromate, sodium dodecyl sulfate (a skin irritant) did not affect B cells or T cells in the three compartments. Moreover, sensitization to the chromate led to dose-dependent decreases in the percentages of CD4(+) T cells and CD8(+) T cells in the DLNs. However, CD4(+) and CD8(+) memory T cells were significantly increased in the blood and DLNs of the chromate-sensitized mice. Additionally, the percentage of B cells in the DLNs but not blood was dose-dependently increased in the chromate-sensitized mice. Histologically, B-cell areas were dramatically enlarged in the DLNs of the chromate-sensitized mice. Thus, this report provides basic information to further elucidate the role of individual lymphocyte subsets in contact hypersensitivity to chromates.","Contact sensitizer potassium dichromate alters lymphocyte populations in draining lymph nodes and blood in mice Abs: ABSTRACT Chromium is a common human contact allergen, but it is not known whether chromates cause contact hypersensitivity by immunological mechanisms similar to those induced by strong haptens. To understand the immunological events of contact hypersensitivity to chromates, we investigated whether and how chromate sensitization alters lymphocyte subsets in draining lymph nodes (DLNs), blood, and spleens in mice. BALB/c mice were sensitized by painting their ears with 0.5% potassium dichromate or vehicle alone on 3 consecutive days. Flow cytometric analysis of lymphocyte surface antigens showed that the chromate exposure significantly increased the percentage of B cells and decreased the percentages of T cells in the DLNs. This was accompanied by a relative increase in T cells and a relative decrease in B cells in peripheral blood. In contrast to the chromate, sodium dodecyl sulfate (a skin irritant) did not affect B cells or T cells in the three compartments. Moreover, sensitization to the chromate led to dose-dependent decreases in the percentages of CD4(+) T cells and CD8(+) T cells in the DLNs. However, CD4(+) and CD8(+) memory T cells were significantly increased in the blood and DLNs of the chromate-sensitized mice. Additionally, the percentage of B cells in the DLNs but not blood was dose-dependently increased in the chromate-sensitized mice. Histologically, B-cell areas were dramatically enlarged in the DLNs of the chromate-sensitized mice. Thus, this report provides basic information to further elucidate the role of individual lymphocyte subsets in contact hypersensitivity to chromates."
730612,Antonini et al. 2005,"Effect of stainless steel manual metal arc welding fume on free radical production, DNA damage, and apoptosis induction","Questions exist concerning the potential carcinogenic effects after welding fume exposure. Welding processes that use stainless steel (SS) materials can produce fumes that may contain metals (e.g., Cr, Ni) known to be carcinogenic to humans. The objective was to determine the effect of in vitro and in vivo welding fume treatment on free radical generation, DNA damage, cytotoxicity and apoptosis induction, all factors possibly involved with the pathogenesis of lung cancer. SS welding fume was collected during manual metal arc welding (MMA). Elemental analysis indicated that the MMA-SS sample was highly soluble in water, and a majority (87%) of the soluble metal was Cr. Using electron spin resonance (ESR), the SS welding fume had the ability to produce the biologically reactive hydroxyl radical (*OH), likely as a result of the reduction of Cr(VI) to Cr(V). In vitro treatment with the MMA-SS sample caused a concentration-dependent increase in DNA damage and lung macrophage death. In addition, a time-dependent increase in the number of apoptotic cells in lung tissue was observed after in vivo treatment with the welding fume. In summary, a soluble MMA-SS welding fume was found to generate reactive oxygen species and cause DNA damage, lung macrophage cytotoxicity and in vivo lung cell apoptosis. These responses have been shown to be involved in various toxicological and carcinogenic processes. The effects observed appear to be related to the soluble component of the MMA-SS sample that is predominately Cr. A more comprehensive in vivo animal study is ongoing in the laboratory that is continuing these experiments to try to elucidate the potential mechanisms that may be involved with welding fume-induced lung disease.","Effect of stainless steel manual metal arc welding fume on free radical production, DNA damage, and apoptosis induction Abs: Questions exist concerning the potential carcinogenic effects after welding fume exposure. Welding processes that use stainless steel (SS) materials can produce fumes that may contain metals (e.g., Cr, Ni) known to be carcinogenic to humans. The objective was to determine the effect of in vitro and in vivo welding fume treatment on free radical generation, DNA damage, cytotoxicity and apoptosis induction, all factors possibly involved with the pathogenesis of lung cancer. SS welding fume was collected during manual metal arc welding (MMA). Elemental analysis indicated that the MMA-SS sample was highly soluble in water, and a majority (87%) of the soluble metal was Cr. Using electron spin resonance (ESR), the SS welding fume had the ability to produce the biologically reactive hydroxyl radical (*OH), likely as a result of the reduction of Cr(VI) to Cr(V). In vitro treatment with the MMA-SS sample caused a concentration-dependent increase in DNA damage and lung macrophage death. In addition, a time-dependent increase in the number of apoptotic cells in lung tissue was observed after in vivo treatment with the welding fume. In summary, a soluble MMA-SS welding fume was found to generate reactive oxygen species and cause DNA damage, lung macrophage cytotoxicity and in vivo lung cell apoptosis. These responses have been shown to be involved in various toxicological and carcinogenic processes. The effects observed appear to be related to the soluble component of the MMA-SS sample that is predominately Cr. A more comprehensive in vivo animal study is ongoing in the laboratory that is continuing these experiments to try to elucidate the potential mechanisms that may be involved with welding fume-induced lung disease."
730128,Siemiatycki et al. 1994,"Occupational risk factors for bladder cancer: Results from a case-control study in Montreal, Quebec, Canada","A population-based case-control study of the associations between various cancers and occupational exposures was carried out in Montreal, Quebec, Canada. Between 1979 and 1986, 484 persons with pathologically confirmed cases of bladder cancer and 1,879 controls with cancers at other sites were interviewed, as was a series of 533 population controls. The job histories of these subjects were evaluated by a team of chemist/hygienists for evidence of exposure to a list of 294 workplace chemicals, and information on relevant non-occupational confounders was obtained. On the basis of results of preliminary analyses and literature review, 19 occupations, 11 industries, and 23 substances were selected for in-depth multivariate analysis. Logistic regression analyses were carried out to estimate the odds ratio between each of these occupational circumstances and bladder cancer. There was weak evidence that the following substances may be risk factors for bladder cancer: natural gas combustion products, aromatic amines, cadmium compounds, photographic products, acrylic fibers, polyethylene, titanium dioxide, and chlorine. Among the substances evaluated which showed no evidence of an association were benzo(a)pyrene, leather dust, and formaldehyde. Several occupations and industries were associated with bladder cancer, including motor vehicle drivers and textile dyers.","Occupational risk factors for bladder cancer: Results from a case-control study in Montreal, Quebec, Canada Abs: A population-based case-control study of the associations between various cancers and occupational exposures was carried out in Montreal, Quebec, Canada. Between 1979 and 1986, 484 persons with pathologically confirmed cases of bladder cancer and 1,879 controls with cancers at other sites were interviewed, as was a series of 533 population controls. The job histories of these subjects were evaluated by a team of chemist/hygienists for evidence of exposure to a list of 294 workplace chemicals, and information on relevant non-occupational confounders was obtained. On the basis of results of preliminary analyses and literature review, 19 occupations, 11 industries, and 23 substances were selected for in-depth multivariate analysis. Logistic regression analyses were carried out to estimate the odds ratio between each of these occupational circumstances and bladder cancer. There was weak evidence that the following substances may be risk factors for bladder cancer: natural gas combustion products, aromatic amines, cadmium compounds, photographic products, acrylic fibers, polyethylene, titanium dioxide, and chlorine. Among the substances evaluated which showed no evidence of an association were benzo(a)pyrene, leather dust, and formaldehyde. Several occupations and industries were associated with bladder cancer, including motor vehicle drivers and textile dyers."
724284,Vergieva 1993,Adverse effects of environmental chemicals on the outcome of human pregnancy,,Adverse effects of environmental chemicals on the outcome of human pregnancy Abs: 
723745,Wise et al. 2011,The genotoxicity of particulate and soluble chromate in sperm whale (physeter macrocephalus) skin fibroblasts,"Hexavalent chromium is a marine pollutant of concern, both for the health of ocean ecosystems and for public health. Hexavalent chromium is known to induce genotoxicity in human and other terrestrial mammals. It is also known to be present in both water and air in the marine environment. However, currently there are limited data concerning both chromium levels and its toxicological effects in marine mammals. This study investigated the cytotoxic and genotoxic effects of soluble and particulate hexavalent chromium in sperm whale skin fibroblasts. Both forms of hexavalent chromium induced concentration-dependent increases in cytotoxicity and genotoxicity indicating that these compounds can be a health risk if the whales are exposed to them. These data support a hypothesis that chromium is a concern in the marine environment in general and for the health of sperm whales in particular.","The genotoxicity of particulate and soluble chromate in sperm whale (physeter macrocephalus) skin fibroblasts Abs: Hexavalent chromium is a marine pollutant of concern, both for the health of ocean ecosystems and for public health. Hexavalent chromium is known to induce genotoxicity in human and other terrestrial mammals. It is also known to be present in both water and air in the marine environment. However, currently there are limited data concerning both chromium levels and its toxicological effects in marine mammals. This study investigated the cytotoxic and genotoxic effects of soluble and particulate hexavalent chromium in sperm whale skin fibroblasts. Both forms of hexavalent chromium induced concentration-dependent increases in cytotoxicity and genotoxicity indicating that these compounds can be a health risk if the whales are exposed to them. These data support a hypothesis that chromium is a concern in the marine environment in general and for the health of sperm whales in particular."
711024,Tajima et al. 2010,Pulmonary injury and antioxidant response in mice exposed to arsenate and hexavalent chromium and their combination,"Chromated copper arsenate, which is used worldwide as a wood preservative, can adversely affect human health. Accumulating evidence suggests that chromium (Cr) and arsenic (As) can potentially disrupt the redox balance and cause respiratory diseases and cancer in humans. The present study was designed to determine the combined toxic effects of these metals in the lungs and to clarify the specific molecules that are stimulated by combined exposure to both metals. Male C57BL/6J mice were intratracheally instilled with arsenate [As(V)], hexavalent chromium [Cr(VI)], or a combination of both metals. Mice were sacrificed 2 days after treatment to collect bronchoalveolar lavage fluid and lung tissue samples. Inflammation, cytotoxicity, apoptosis, and oxidative stress markers were measured. Our results indicated that administration of Cr(VI) alone or in combination with As(V) induced neutrophil-dominant inflammation as well as phosphorylation of mitogen-activated protein kinases; effects of treatment with As(V) alone were comparatively less potent. By analyzing the production of interleukin-6 and activity of lactate dehydrogenase and caspase, we confirmed that co-treatment intensified pulmonary injury and that it was accompanied by oxidative stress, as confirmed by marked increases in the production of reactive oxygen species, reduced glutathione content, and thioredoxin reductase (TRXRD) activity. Expressed mRNA levels of heme oxygenase-1, glutamylcysteine ligase, glutathione peroxidase 2, thioredoxin (TRX) 1, and TRXRD1 were also enhanced by co-treatment, whereas treatment with As(V) alone reduced the mRNA expression level of TRX2. Our data suggest that co-treatment with As(V) exacerbated Cr(VI)-induced pulmonary injury and that this effect may be exerted through a disruption in the balance among several antioxidant genes.","Pulmonary injury and antioxidant response in mice exposed to arsenate and hexavalent chromium and their combination Abs: Chromated copper arsenate, which is used worldwide as a wood preservative, can adversely affect human health. Accumulating evidence suggests that chromium (Cr) and arsenic (As) can potentially disrupt the redox balance and cause respiratory diseases and cancer in humans. The present study was designed to determine the combined toxic effects of these metals in the lungs and to clarify the specific molecules that are stimulated by combined exposure to both metals. Male C57BL/6J mice were intratracheally instilled with arsenate [As(V)], hexavalent chromium [Cr(VI)], or a combination of both metals. Mice were sacrificed 2 days after treatment to collect bronchoalveolar lavage fluid and lung tissue samples. Inflammation, cytotoxicity, apoptosis, and oxidative stress markers were measured. Our results indicated that administration of Cr(VI) alone or in combination with As(V) induced neutrophil-dominant inflammation as well as phosphorylation of mitogen-activated protein kinases; effects of treatment with As(V) alone were comparatively less potent. By analyzing the production of interleukin-6 and activity of lactate dehydrogenase and caspase, we confirmed that co-treatment intensified pulmonary injury and that it was accompanied by oxidative stress, as confirmed by marked increases in the production of reactive oxygen species, reduced glutathione content, and thioredoxin reductase (TRXRD) activity. Expressed mRNA levels of heme oxygenase-1, glutamylcysteine ligase, glutathione peroxidase 2, thioredoxin (TRX) 1, and TRXRD1 were also enhanced by co-treatment, whereas treatment with As(V) alone reduced the mRNA expression level of TRX2. Our data suggest that co-treatment with As(V) exacerbated Cr(VI)-induced pulmonary injury and that this effect may be exerted through a disruption in the balance among several antioxidant genes."
710735,Newton and  Lilly 1986,Tissue-specific clastogenic effects of chromium and selenium salts in vivo,"The clastogenic effects of inorganic compounds of chromium (K2Cr2O7) and selenium (Na2SeO3) on the chromosomes of rat lymphocytes and bone marrow have been investigated. In vitro exposure of rat lymphocytes to K2Cr2O7 gave highly significant and dose-related increases in abnormal metaphases at 6 concentrations from 7 X 10(-6) M to 3.2 X 10(-5) M. Similar in vitro exposure of lymphocytes to Na2SeO3 showed that it was clastogenic at concentrations of 7.5 X 10(-6) M, 1 X 10(-5) M and 2.5 X 10(-5) M. However, with in vivo exposures of K2Cr2O7 (i.p. and i.v.) it was only possible to demonstrate clastogenicity in lymphocytes at sublethal concentrations (36 mg/kg X 2 i.v.) and then only if the results were tested against all controls combined (1900 metaphases, 19 animals). On the other hand, very highly significant clastogenic effects were obtained in bone marrow cells exposed in vivo to K2Cr2O7 at 21 mg/kg i.p. and 12, 18, 24 and 36 mg/kg i.v. In vivo exposure to Na2SeO3, with concentrations up to 6 mg/kg X 2 i.v., caused no significant increase in abnormal metaphases in lymphocytes but 5 and 6 mg/kg X 2 i.v. caused a significant increase in abnormal metaphases in bone marrow. These results suggest that K2Cr2O7 and Na2SeO3 are acting as 'S' dependent chemicals. Although not directly comparable, they are compatible with the warnings given by other authors both on the detection of aberrations in lymphocytes after chronic exposure in man and on short-term testing of lymphocytes at low doses related to human exposure.","Tissue-specific clastogenic effects of chromium and selenium salts in vivo Abs: The clastogenic effects of inorganic compounds of chromium (K2Cr2O7) and selenium (Na2SeO3) on the chromosomes of rat lymphocytes and bone marrow have been investigated. In vitro exposure of rat lymphocytes to K2Cr2O7 gave highly significant and dose-related increases in abnormal metaphases at 6 concentrations from 7 X 10(-6) M to 3.2 X 10(-5) M. Similar in vitro exposure of lymphocytes to Na2SeO3 showed that it was clastogenic at concentrations of 7.5 X 10(-6) M, 1 X 10(-5) M and 2.5 X 10(-5) M. However, with in vivo exposures of K2Cr2O7 (i.p. and i.v.) it was only possible to demonstrate clastogenicity in lymphocytes at sublethal concentrations (36 mg/kg X 2 i.v.) and then only if the results were tested against all controls combined (1900 metaphases, 19 animals). On the other hand, very highly significant clastogenic effects were obtained in bone marrow cells exposed in vivo to K2Cr2O7 at 21 mg/kg i.p. and 12, 18, 24 and 36 mg/kg i.v. In vivo exposure to Na2SeO3, with concentrations up to 6 mg/kg X 2 i.v., caused no significant increase in abnormal metaphases in lymphocytes but 5 and 6 mg/kg X 2 i.v. caused a significant increase in abnormal metaphases in bone marrow. These results suggest that K2Cr2O7 and Na2SeO3 are acting as 'S' dependent chemicals. Although not directly comparable, they are compatible with the warnings given by other authors both on the detection of aberrations in lymphocytes after chronic exposure in man and on short-term testing of lymphocytes at low doses related to human exposure."
700925,Albert et al. 2005,Analysis of a cluster of cases of Wegener granulomatosis,"BACKGROUND: Wegener granulomatosis is a chronic inflammatory autoimmune disease of unknown etiology. The sporadic occurrence, lack of familial or genetic associations, and rising incidence suggest possible exposure to environmental agents as causative for this disease. OBJECTIVE: The objective of this study was to examine possible environmental triggers of Wegener granulomatosis. METHODS: While conducting an environmental survey of potential precipitants of Wegener granulomatosis on a cohort of patients seen at Doylestown Hospital and at the University of Pennsylvania, we identified a cluster of cases in the Dublin, Pennsylvania, region. Through hospital records and patient contacts, we located 7 cases diagnosed in a 3-year period within a 10-mile radius of an Environmental Protection Agency (EPA) Superfund toxic waste site. The radius of inclusion represents a population of approximately 50,000 individuals. Assuming complete ascertainment of cases--which is unlikely given the methods used to acquire patients--the prevalence is 2- to 4-fold greater than the expected rate of 3 per 100,000. We identified toxins at or above ""action level"" within the demarcated geographic region using published data from the EPA. Furthermore, we queried patients regarding their particular chemical exposures. RESULTS: These patients with Wegener granulomatosis were possibly exposed to high levels of trichloroethylene (TCE), vinyl chloride, methyl tertiary-butyl ether (MTBE), dichloroethene (DCE), and chromic acid from several industrial waste sites within the area. Additionally, these patients reported a total of greater than 30 possible exposures, including the aforesaid chemical contaminants. Three of 5 patients whose water source is known had well water that exposed them to industrial runoff and necessitated EPA intervention. CONCLUSION: This data, along with other epidemiologic studies, suggest possible toxic exposures as potentially correctable risk factors for Wegener granulomatosis. We encourage clinicians to seek data that suggests an unusual environmental exposure and to solicit information that might implicate an industrial source for these exposures.","Analysis of a cluster of cases of Wegener granulomatosis Abs: BACKGROUND: Wegener granulomatosis is a chronic inflammatory autoimmune disease of unknown etiology. The sporadic occurrence, lack of familial or genetic associations, and rising incidence suggest possible exposure to environmental agents as causative for this disease. OBJECTIVE: The objective of this study was to examine possible environmental triggers of Wegener granulomatosis. METHODS: While conducting an environmental survey of potential precipitants of Wegener granulomatosis on a cohort of patients seen at Doylestown Hospital and at the University of Pennsylvania, we identified a cluster of cases in the Dublin, Pennsylvania, region. Through hospital records and patient contacts, we located 7 cases diagnosed in a 3-year period within a 10-mile radius of an Environmental Protection Agency (EPA) Superfund toxic waste site. The radius of inclusion represents a population of approximately 50,000 individuals. Assuming complete ascertainment of cases--which is unlikely given the methods used to acquire patients--the prevalence is 2- to 4-fold greater than the expected rate of 3 per 100,000. We identified toxins at or above ""action level"" within the demarcated geographic region using published data from the EPA. Furthermore, we queried patients regarding their particular chemical exposures. RESULTS: These patients with Wegener granulomatosis were possibly exposed to high levels of trichloroethylene (TCE), vinyl chloride, methyl tertiary-butyl ether (MTBE), dichloroethene (DCE), and chromic acid from several industrial waste sites within the area. Additionally, these patients reported a total of greater than 30 possible exposures, including the aforesaid chemical contaminants. Three of 5 patients whose water source is known had well water that exposed them to industrial runoff and necessitated EPA intervention. CONCLUSION: This data, along with other epidemiologic studies, suggest possible toxic exposures as potentially correctable risk factors for Wegener granulomatosis. We encourage clinicians to seek data that suggests an unusual environmental exposure and to solicit information that might implicate an industrial source for these exposures."
700749,Hayashi et al. 1982,High-sensitivity in micronucleus induction of a mouse strain (MS),,High-sensitivity in micronucleus induction of a mouse strain (MS) Abs: 
699919,Gibb et al. 2000,Lung cancer among workers in chromium chemical production,"An elevated risk of lung cancer among workers in chromate production facilities has previously been reported. This excess risk is believed to be the result of exposure to hexavalent chromium. There have been mixed reports about whether trivalent chromium exposure is also associated with an excess lung cancer risk. Previous studies of measured hexavalent chromium exposure and lung cancer risk have not examined cigarette smoking as a risk factor.<br /><br /> A cohort of 2,357 workers first employed between 1950 and 1974 at a chromate production plant was identified. Vital status of the workers was followed until December 31, 1992. Work histories of cohort members were compiled from the beginning of employment through 1985, the year the plant closed. Annual average exposure estimates, based on historical exposure measurements, were made for each job title in the plant for the years 1950-1985. These exposure estimates were used to calculate the cumulative hexavalent chromium exposure of each member of the study population. Following closure of the plant, settled dust samples were collected and analyzed for hexavalent and trivalent chromium. The trivalent/hexavalent concentration ratios in each plant area were combined with historic air-sampling data to estimate cumulative trivalent chromium exposure for each individual in the study cohort. Smoking status (yes/no) as of the beginning of employment and clinical signs of potential chromium irritation were identified from company records.<br /><br /> Cumulative hexavalent chromium exposure showed a strong dose-response relationship for lung cancer. Clinical signs of irritation, cumulative trivalent chromium exposure, and duration of work were not found to be associated with a risk of lung cancer when included in a proportional hazards model with cumulative hexavalent chromium exposure and smoking. Age-specific data on cumulative hexavalent chromium exposure, observed and expected numbers of lung cancer cases, and person-years of observation are provided.<br /><br /> Cumulative hexavalent chromium exposure was associated with an increased lung cancer risk; cumulative trivalent chromium exposure was not. The excess risk of lung cancer associated with cumulative hexavalent chromium exposure was not confounded by smoking status. The current study offers the best quantitative evidence to date of the relationship between hexavalent chromium exposure and lung cancer. Am. J. Ind. Med. 38:115-126, 2000. Published 2000 Wiley-Liss, Inc.","Lung cancer among workers in chromium chemical production Abs: An elevated risk of lung cancer among workers in chromate production facilities has previously been reported. This excess risk is believed to be the result of exposure to hexavalent chromium. There have been mixed reports about whether trivalent chromium exposure is also associated with an excess lung cancer risk. Previous studies of measured hexavalent chromium exposure and lung cancer risk have not examined cigarette smoking as a risk factor.<br /><br /> A cohort of 2,357 workers first employed between 1950 and 1974 at a chromate production plant was identified. Vital status of the workers was followed until December 31, 1992. Work histories of cohort members were compiled from the beginning of employment through 1985, the year the plant closed. Annual average exposure estimates, based on historical exposure measurements, were made for each job title in the plant for the years 1950-1985. These exposure estimates were used to calculate the cumulative hexavalent chromium exposure of each member of the study population. Following closure of the plant, settled dust samples were collected and analyzed for hexavalent and trivalent chromium. The trivalent/hexavalent concentration ratios in each plant area were combined with historic air-sampling data to estimate cumulative trivalent chromium exposure for each individual in the study cohort. Smoking status (yes/no) as of the beginning of employment and clinical signs of potential chromium irritation were identified from company records.<br /><br /> Cumulative hexavalent chromium exposure showed a strong dose-response relationship for lung cancer. Clinical signs of irritation, cumulative trivalent chromium exposure, and duration of work were not found to be associated with a risk of lung cancer when included in a proportional hazards model with cumulative hexavalent chromium exposure and smoking. Age-specific data on cumulative hexavalent chromium exposure, observed and expected numbers of lung cancer cases, and person-years of observation are provided.<br /><br /> Cumulative hexavalent chromium exposure was associated with an increased lung cancer risk; cumulative trivalent chromium exposure was not. The excess risk of lung cancer associated with cumulative hexavalent chromium exposure was not confounded by smoking status. The current study offers the best quantitative evidence to date of the relationship between hexavalent chromium exposure and lung cancer. Am. J. Ind. Med. 38:115-126, 2000. Published 2000 Wiley-Liss, Inc."
689869,Li Chen et al. 2009,Particulate hexavalent chromium is cytotoxic and genotoxic to the North Atlantic right whale (Eubalaena glacialis) lung and skin fibroblasts,"Hexavalent chromium compounds are present in the atmosphere and oceans and are established mutagens and carcinogens in human and terrestrial mammals. However, the adverse effects of these toxicants in marine mammals are uncertain. Previously, we reported that North Atlantic right whales, one of the most endangered great whales, have tissue chromium levels that are high, levels that may pose a risk to the whale's health. Furthermore, the study suggested that inhalation may be an important exposure route. Exposure to chromium through inhalation is mainly because of particulate compounds. However, the toxicity of particulate chromium compounds in marine mammal cells is unknown. Accordingly, in this study, we tested the cytotoxic and genotoxic effects of particulate hexavalent chromium in primary cultured lung and skin fibroblasts from the endangered North Atlantic right whale. Cytotoxicity was measured by clonogenic survival assay, and genotoxicity was measured as production of chromosome aberrations. Particulate hexavalent chromium induced cytotoxicity and genotoxicity in a concentration-dependent manner in both right whale lung and skin fibroblasts. Lung fibroblasts were more resistant to chromium cytotoxicity, but presented with more chromosome damage than skin fibroblasts. These data further support the hypothesis that chromium may be a health concern for the endangered North Atlantic right whale.","Particulate hexavalent chromium is cytotoxic and genotoxic to the North Atlantic right whale (Eubalaena glacialis) lung and skin fibroblasts Abs: Hexavalent chromium compounds are present in the atmosphere and oceans and are established mutagens and carcinogens in human and terrestrial mammals. However, the adverse effects of these toxicants in marine mammals are uncertain. Previously, we reported that North Atlantic right whales, one of the most endangered great whales, have tissue chromium levels that are high, levels that may pose a risk to the whale's health. Furthermore, the study suggested that inhalation may be an important exposure route. Exposure to chromium through inhalation is mainly because of particulate compounds. However, the toxicity of particulate chromium compounds in marine mammal cells is unknown. Accordingly, in this study, we tested the cytotoxic and genotoxic effects of particulate hexavalent chromium in primary cultured lung and skin fibroblasts from the endangered North Atlantic right whale. Cytotoxicity was measured by clonogenic survival assay, and genotoxicity was measured as production of chromosome aberrations. Particulate hexavalent chromium induced cytotoxicity and genotoxicity in a concentration-dependent manner in both right whale lung and skin fibroblasts. Lung fibroblasts were more resistant to chromium cytotoxicity, but presented with more chromosome damage than skin fibroblasts. These data further support the hypothesis that chromium may be a health concern for the endangered North Atlantic right whale."
688911,Ikarashi et al. 1992,"Differences of draining lymph node cell proliferation among mice, rats and guinea pigs following exposure to metal allergens","Contact sensitivities of three well known metal allergens (nickel sulfate, potassium dichromate and cobalt chloride) were examined using the local lymph node assay in CBA/N mice, F344 rats and Hartley guinea pigs. The effect of various species sera on lymph node cell (LNC) proliferation was also investigated. Exposure to potassium dichromate and cobalt chloride induced significant LNC proliferative responses in the three species. The LNC responses to potassium dichromate in the rats were higher than those in the mice and guinea pigs. Mice exhibited the highest response to cobalt chloride among the three species, whereas, exposure to nickel sulfate failed to induce a marked LNC proliferation. Increased draining lymph node weights and LNC numbers were also observed following exposure to the metal salts. However, these parameters were less sensitive compared with the LNC proliferative response. There was a large difference in the lymph node weight between individual guinea pigs. The [methyl-3H]thymidine incorporation into LNC of each species cultured in the presence of the homologous serum in vitro was lower than in the presence or absence of fetal calf serum. However, there was no significant difference in stimulation indices among the different culture conditions. The local lymph node assay may be performed in rats as well as in mice for the detection of metal allergens.","Differences of draining lymph node cell proliferation among mice, rats and guinea pigs following exposure to metal allergens Abs: Contact sensitivities of three well known metal allergens (nickel sulfate, potassium dichromate and cobalt chloride) were examined using the local lymph node assay in CBA/N mice, F344 rats and Hartley guinea pigs. The effect of various species sera on lymph node cell (LNC) proliferation was also investigated. Exposure to potassium dichromate and cobalt chloride induced significant LNC proliferative responses in the three species. The LNC responses to potassium dichromate in the rats were higher than those in the mice and guinea pigs. Mice exhibited the highest response to cobalt chloride among the three species, whereas, exposure to nickel sulfate failed to induce a marked LNC proliferation. Increased draining lymph node weights and LNC numbers were also observed following exposure to the metal salts. However, these parameters were less sensitive compared with the LNC proliferative response. There was a large difference in the lymph node weight between individual guinea pigs. The [methyl-3H]thymidine incorporation into LNC of each species cultured in the presence of the homologous serum in vitro was lower than in the presence or absence of fetal calf serum. However, there was no significant difference in stimulation indices among the different culture conditions. The local lymph node assay may be performed in rats as well as in mice for the detection of metal allergens."
688799,Ishidate et al. 1988,A comparative analysis of data on the clastogenicity of 951 chemical substances tested in mammalian cell cultures,A literature review was conducted using original papers published during 1964–1985 on the in vitro clastogenicity of chemical substances. Results of tests on 951 chemical substances were abstracted from over 240 reports to form the database. The evaluation of these data relied on each author's original conclusion on a positive or negative outcome.,A comparative analysis of data on the clastogenicity of 951 chemical substances tested in mammalian cell cultures Abs: A literature review was conducted using original papers published during 1964–1985 on the in vitro clastogenicity of chemical substances. Results of tests on 951 chemical substances were abstracted from over 240 reports to form the database. The evaluation of these data relied on each author's original conclusion on a positive or negative outcome.
684096,Caspary et al. 1988,Evaluation of the L5178Y mouse lymphoma cell mutagenesis assay: interlaboratory reproducibility and assessment,"The L5178Y mouse lymphoma cell mutagenesis assay is used to detect the mutagenic activity of chemicals in a mammalian cell system. To evaluate this assay we compared the results of assays performed independently on 63 chemicals by laboratories at SRI International and Litton Bionetics, Inc. The two laboratories used similar protocols. The solvent and positive control mutant frequencies and cloning efficiencies obtained by the two laboratories were similar, which justified the use of the same quality-control criteria and analytical procedures for analyzing the results from both laboratories. The rate of concordance between the two laboratories was 92% for tests in the absence of S9 activation and 95% for tests in its presence. The results of the assays agreed for 57 of the 63 chemicals; three chemicals could not be compared because there were questionable calls in at least one of the laboratories; the results disagreed for the three remaining chemicals. The concordance rate for these overall assay evaluations was 95%. The interlaboratory concordance rates were similar to concordance rates for replicate experiments within the laboratories (96% at LBI, 94% at SRI). The mouse lymphoma cell mutagenicity results are concordant with the rodent chronic assay results in 78% of 50 chemicals and with the Salmonella assay results in 79% of 56 chemicals. Fifteen carcinogens were examined for genotoxic effects in mouse lymphoma, Salmonella, Chinese hamster ovary (CHO) chromosomal aberration, and CHO sister chromatid exchange assay. Eight of these were positive in all four assays. Of the seven noncarcinogens that were tested in these four assays, none was negative in all four. The main conclusion to be drawn from this study is that the mouse lymphoma cell forward mutation assay, as performed and evaluated in this study, detects chemical mutagenicity in a manner that is highly consistent with other genetic endpoints as well as rodent carcinogenicity studies. Thus the assay quality control and response criteria established in this study led not only to a high degree of reproducibility but also to an apparently reliable detection of mutagenic activity.","Evaluation of the L5178Y mouse lymphoma cell mutagenesis assay: interlaboratory reproducibility and assessment Abs: The L5178Y mouse lymphoma cell mutagenesis assay is used to detect the mutagenic activity of chemicals in a mammalian cell system. To evaluate this assay we compared the results of assays performed independently on 63 chemicals by laboratories at SRI International and Litton Bionetics, Inc. The two laboratories used similar protocols. The solvent and positive control mutant frequencies and cloning efficiencies obtained by the two laboratories were similar, which justified the use of the same quality-control criteria and analytical procedures for analyzing the results from both laboratories. The rate of concordance between the two laboratories was 92% for tests in the absence of S9 activation and 95% for tests in its presence. The results of the assays agreed for 57 of the 63 chemicals; three chemicals could not be compared because there were questionable calls in at least one of the laboratories; the results disagreed for the three remaining chemicals. The concordance rate for these overall assay evaluations was 95%. The interlaboratory concordance rates were similar to concordance rates for replicate experiments within the laboratories (96% at LBI, 94% at SRI). The mouse lymphoma cell mutagenicity results are concordant with the rodent chronic assay results in 78% of 50 chemicals and with the Salmonella assay results in 79% of 56 chemicals. Fifteen carcinogens were examined for genotoxic effects in mouse lymphoma, Salmonella, Chinese hamster ovary (CHO) chromosomal aberration, and CHO sister chromatid exchange assay. Eight of these were positive in all four assays. Of the seven noncarcinogens that were tested in these four assays, none was negative in all four. The main conclusion to be drawn from this study is that the mouse lymphoma cell forward mutation assay, as performed and evaluated in this study, detects chemical mutagenicity in a manner that is highly consistent with other genetic endpoints as well as rodent carcinogenicity studies. Thus the assay quality control and response criteria established in this study led not only to a high degree of reproducibility but also to an apparently reliable detection of mutagenic activity."
677658,Greenway and  Gerstenberger 2010,"An evaluation of lead contamination in plastic toys collected from day care centers in the Las Vegas Valley, Nevada, USA","Childhood exposure to environmental lead continues to be a major health concern. This study examined lead content within the plastic of children's toys collected from licensed day care centers in the Las Vegas valley, Nevada. It was hypothesized that the use of lead as a plastics stabilizer would result in elevated lead (?600 ppm) in polyvinyl chloride plastics (PVC) compared to non-PVC plastics. It was also hypothesized that, due to the use of lead chromate as a coloring agent, yellow toys would contain higher concentrations of lead (?600 ppm) than toys of other colors. Toy samples were limited to those found in day care centers in Las Vegas, Nevada. 10 day care centers were visited and approximately 50 toy samples were taken from each center. Of the 535 toys tested, 29 contained lead in excess of 600 parts per million (ppm). Of those 29 toys, 20 were PVC and 17 were yellow. Both of the two hypotheses were strongly supported by the data.","An evaluation of lead contamination in plastic toys collected from day care centers in the Las Vegas Valley, Nevada, USA Abs: Childhood exposure to environmental lead continues to be a major health concern. This study examined lead content within the plastic of children's toys collected from licensed day care centers in the Las Vegas valley, Nevada. It was hypothesized that the use of lead as a plastics stabilizer would result in elevated lead (?600 ppm) in polyvinyl chloride plastics (PVC) compared to non-PVC plastics. It was also hypothesized that, due to the use of lead chromate as a coloring agent, yellow toys would contain higher concentrations of lead (?600 ppm) than toys of other colors. Toy samples were limited to those found in day care centers in Las Vegas, Nevada. 10 day care centers were visited and approximately 50 toy samples were taken from each center. Of the 535 toys tested, 29 contained lead in excess of 600 parts per million (ppm). Of those 29 toys, 20 were PVC and 17 were yellow. Both of the two hypotheses were strongly supported by the data."
677643,Wedrychowski et al. 1986,DNA-protein crosslinking by heavy metals in Novikoff hepatoma,"Crosslinking of proteins to DNA was studied in live intact Novikoff ascites hepatoma cells exposed in vitro to salts of chromium VI, III, and II, nickel II, cadmium II, and to CoCl2, As2O3, and AlK(SO4)2. DNA-protein complexes were separated by high-speed centrifugation of cells solubilized in buffered 4% sodium dodecyl sulfate and assayed by polyacrylamide gel electrophoresis. Hexavalent chromium compounds formed DNA-protein complexes very efficiently. The trivalent, poorly soluble, cupric chromite was nearly as efficient crosslinker as hexavalent Cr, perhaps because phagocytosis facilitated its entry into the cells. The more basic divalent form produced hardly any crosslinks. Most of the crosslinked proteins were common to all of the chromium salts employed. Nickel salts formed DNA-protein crosslinks less efficiently. Most proteins crosslinked by this metal had a high molecular weight ranging from 94,000 to 200,000. There was little qualitative difference between the crosslinked protein patterns for several various nickel (II) salts. Similar results were obtained for cells incubated with cadmium salts. Most of the proteins crosslinked by cadmium had high molecular weights and were similar to those crosslinked by nickel (II). Relatively weak, but significant, Crosslinking was also observed when the Novikoff hepatoma cells were exposed to CoCl2, As2O3, or AlK(SO4)2.","DNA-protein crosslinking by heavy metals in Novikoff hepatoma Abs: Crosslinking of proteins to DNA was studied in live intact Novikoff ascites hepatoma cells exposed in vitro to salts of chromium VI, III, and II, nickel II, cadmium II, and to CoCl2, As2O3, and AlK(SO4)2. DNA-protein complexes were separated by high-speed centrifugation of cells solubilized in buffered 4% sodium dodecyl sulfate and assayed by polyacrylamide gel electrophoresis. Hexavalent chromium compounds formed DNA-protein complexes very efficiently. The trivalent, poorly soluble, cupric chromite was nearly as efficient crosslinker as hexavalent Cr, perhaps because phagocytosis facilitated its entry into the cells. The more basic divalent form produced hardly any crosslinks. Most of the crosslinked proteins were common to all of the chromium salts employed. Nickel salts formed DNA-protein crosslinks less efficiently. Most proteins crosslinked by this metal had a high molecular weight ranging from 94,000 to 200,000. There was little qualitative difference between the crosslinked protein patterns for several various nickel (II) salts. Similar results were obtained for cells incubated with cadmium salts. Most of the proteins crosslinked by cadmium had high molecular weights and were similar to those crosslinked by nickel (II). Relatively weak, but significant, Crosslinking was also observed when the Novikoff hepatoma cells were exposed to CoCl2, As2O3, or AlK(SO4)2."
677639,Hamilton-Koch et al. 1986,Metal-induced DNA damage and repair in human diploid fibroblasts and Chinese hamster ovary cells,"Cloning efficiency and DNA strand breaks induction were compared in human diploid fibroblasts (HSBP) and chinese hamster ovary (CHO) cells treated with various metal salts. Cadmium (Cd2+), nickel (Ni2+) and chromate (Cr2O7) reduced the cloning efficiency of HSBP cells more than that of CHO cells whereas the reverse was true after treatment with mercury (Hg2+), manganese (Mn2+) and cobalt (Co2+). The effects on cloning efficiency did not consistently correlate with DNA strand breaking activity as all metals except Cr(VI) were more effective at producing DNA strand breaks in CHO cells than in human cells. The differential responses of the two cell types was shown to be only partially due to differences in cellular uptake of metals. DNA breaks induced in human cells by Hg2+ and Cr2O7 were shown most likely to be alkaline labile sites rather than true strand breaks since no damage was detected in a nick translation assay which measures the amount of free 3'-OH terminals. Damage induced by Mn2+ and Co2+, however, appeared to be comprised at least in part by true DNA strand breaks. DNA damage was also induced in HSBP cells following treatment with selenium but only in the presence of reduced glutathione. These studies indicate that DNA damage is not as major a consequence following some metal treatments in human cells as it appears to be in rodent cells. This suggests that rodent models for risk estimation of metal-induced tumorigenesis may not always be appropriate for extrapolation to humans.","Metal-induced DNA damage and repair in human diploid fibroblasts and Chinese hamster ovary cells Abs: Cloning efficiency and DNA strand breaks induction were compared in human diploid fibroblasts (HSBP) and chinese hamster ovary (CHO) cells treated with various metal salts. Cadmium (Cd2+), nickel (Ni2+) and chromate (Cr2O7) reduced the cloning efficiency of HSBP cells more than that of CHO cells whereas the reverse was true after treatment with mercury (Hg2+), manganese (Mn2+) and cobalt (Co2+). The effects on cloning efficiency did not consistently correlate with DNA strand breaking activity as all metals except Cr(VI) were more effective at producing DNA strand breaks in CHO cells than in human cells. The differential responses of the two cell types was shown to be only partially due to differences in cellular uptake of metals. DNA breaks induced in human cells by Hg2+ and Cr2O7 were shown most likely to be alkaline labile sites rather than true strand breaks since no damage was detected in a nick translation assay which measures the amount of free 3'-OH terminals. Damage induced by Mn2+ and Co2+, however, appeared to be comprised at least in part by true DNA strand breaks. DNA damage was also induced in HSBP cells following treatment with selenium but only in the presence of reduced glutathione. These studies indicate that DNA damage is not as major a consequence following some metal treatments in human cells as it appears to be in rodent cells. This suggests that rodent models for risk estimation of metal-induced tumorigenesis may not always be appropriate for extrapolation to humans."
677603,Tso and  Fung 1981,Mutagenicity of metallic cations,"Of the seven putative carcinogenic cations tested by the Salmonella assay for mutagenicity, only chromium at its +6 oxidation state was found to be mutagenic. The validity of the Salmonella assay in screening metallic and/or organometallic cations are discussed, as are the explanations to this discrepancy.","Mutagenicity of metallic cations Abs: Of the seven putative carcinogenic cations tested by the Salmonella assay for mutagenicity, only chromium at its +6 oxidation state was found to be mutagenic. The validity of the Salmonella assay in screening metallic and/or organometallic cations are discussed, as are the explanations to this discrepancy."
677596,Kharab and  Singh 1987,"Induction of respiratory deficiency in yeast by salts of chromium, arsenic, cobalt and lead",BIOSIS COPYRIGHT: BIOL ABS. RRM SACCHAROMYCES-CEREVISIAE HEAVY METAL TOXICITY,"Induction of respiratory deficiency in yeast by salts of chromium, arsenic, cobalt and lead Abs: BIOSIS COPYRIGHT: BIOL ABS. RRM SACCHAROMYCES-CEREVISIAE HEAVY METAL TOXICITY"
672992,Liden and  Wahlberg 1994,Cross-reactivity to metal compounds studied in guinea pigs induced with chromate or cobalt,"Multiple sensitivity to metals is often seen in humans. This may be due to cross-reactivity or to multiple sensitization. The pattern of cross-reactivity to some metal compounds was studied, using the guinea pig maximization test method. Animals were induced with K2Cr2O7 and CoCl2, respectively, and then challenged with K2Cr2O7, CoCl2, NiSO4, PdCl2 and RhCl3. No simultaneous reactivity was recorded. This supports the view that simultaneous reactivity in patients to nickel-cobalt and to chromate-cobalt is due to multiple exposure and sensitization, and not to cross-reactivity. The purity of the test compounds was analysed.","Cross-reactivity to metal compounds studied in guinea pigs induced with chromate or cobalt Abs: Multiple sensitivity to metals is often seen in humans. This may be due to cross-reactivity or to multiple sensitization. The pattern of cross-reactivity to some metal compounds was studied, using the guinea pig maximization test method. Animals were induced with K2Cr2O7 and CoCl2, respectively, and then challenged with K2Cr2O7, CoCl2, NiSO4, PdCl2 and RhCl3. No simultaneous reactivity was recorded. This supports the view that simultaneous reactivity in patients to nickel-cobalt and to chromate-cobalt is due to multiple exposure and sensitization, and not to cross-reactivity. The purity of the test compounds was analysed."
672989,Hariya et al. 1999,Development of a non-radioactive endpoint in a modified local lymph node assay,"A murine local lymph node assay (LLNA) has been developed as an alternative to guinea pig models for contact sensitization testing. Although the LLNA appears to be a little less sensitive than the most stringent of guinea pig assays, it provides a rapid, objective, quantitative and cost-effective method for screening strong contact sensitizers and has advantages with respect to animal welfare. However, a potential disadvantage is the need for the use of radioactive material. We have reported previously that an ex vivo assay based on similar principles to the original in vivo LLNA, but using a non-radioactive endopoint, was valid for the prediction of strong sensitizers. This ex vivo assay was not sensitive enough to allow prediction of moderately potent ones. In this study, we propose a new parameter, Corrected IL-2 Index (CII), for the prediction of moderate sensitizers. To obtain CII the IL-2 release in the supernatant of the cell culture is corrected for lymph node weight ratio and ratio of CD4-positive subset. We found that CII predicted the allergenicity of moderate sensitizers, including the ones recommended by the OECD in guideline 406, such as mercaptobenzothiazole and hexyl cinnamic aldehyde. The allergenicity of metal salts, such as potassium dichromate, ammonium tetrachloroplatinate and cobalt chloride, was also predicted by the CII. We conclude that the use of CII as an index significantly increases the sensitivity of the ex vivo method so that moderate sensitizers may also be detected.","Development of a non-radioactive endpoint in a modified local lymph node assay Abs: A murine local lymph node assay (LLNA) has been developed as an alternative to guinea pig models for contact sensitization testing. Although the LLNA appears to be a little less sensitive than the most stringent of guinea pig assays, it provides a rapid, objective, quantitative and cost-effective method for screening strong contact sensitizers and has advantages with respect to animal welfare. However, a potential disadvantage is the need for the use of radioactive material. We have reported previously that an ex vivo assay based on similar principles to the original in vivo LLNA, but using a non-radioactive endopoint, was valid for the prediction of strong sensitizers. This ex vivo assay was not sensitive enough to allow prediction of moderately potent ones. In this study, we propose a new parameter, Corrected IL-2 Index (CII), for the prediction of moderate sensitizers. To obtain CII the IL-2 release in the supernatant of the cell culture is corrected for lymph node weight ratio and ratio of CD4-positive subset. We found that CII predicted the allergenicity of moderate sensitizers, including the ones recommended by the OECD in guideline 406, such as mercaptobenzothiazole and hexyl cinnamic aldehyde. The allergenicity of metal salts, such as potassium dichromate, ammonium tetrachloroplatinate and cobalt chloride, was also predicted by the CII. We conclude that the use of CII as an index significantly increases the sensitivity of the ex vivo method so that moderate sensitizers may also be detected."
671478,Thompson et al. 2011,Application of the U.S. EPA mode of action framework for purposes of guiding future research: A case study involving the oral carcinogenicity of hexavalent chromium,"Mode of action (MOA) analysis provides a systematic description of key events leading to adverse health effects in animal bioassays for the purpose of informing human health risk assessment. Uncertainties and data gaps identified in the MOA analysis may also be used to guide future research to improve understanding of the MOAs underlying a specific toxic response and foster development of toxicokinetic and toxicodynamic models. An MOA analysis, consistent with approaches outlined in the MOA Framework as described in the Guidelines for Carcinogen Risk Assessment, was conducted to evaluate small intestinal tumors observed in mice chronically exposed to relatively high concentrations of hexavalent chromium (Cr(VI)) in drinking water. Based on review of the literature, key events in the MOA are hypothesized to include saturation of the reductive capacity of the upper gastrointestinal tract, absorption of Cr(VI) into the intestinal epithelium, oxidative stress and inflammation, cell proliferation, direct and/or indirect DNA modification, and mutagenesis. Although available data generally support the plausibility of these key events, several unresolved questions and data gaps were identified, highlighting the need for obtaining critical toxicokinetic and toxicodynamic data in the target tissue and in the low-dose range. Experimental assays that can address these data gaps are discussed along with strategies for comparisons between responsive and nonresponsive tissues and species. This analysis provides a practical application of MOA Framework guidance and is instructive for the design of studies to improve upon the information available for quantitative risk assessment.","Application of the U.S. EPA mode of action framework for purposes of guiding future research: A case study involving the oral carcinogenicity of hexavalent chromium Abs: Mode of action (MOA) analysis provides a systematic description of key events leading to adverse health effects in animal bioassays for the purpose of informing human health risk assessment. Uncertainties and data gaps identified in the MOA analysis may also be used to guide future research to improve understanding of the MOAs underlying a specific toxic response and foster development of toxicokinetic and toxicodynamic models. An MOA analysis, consistent with approaches outlined in the MOA Framework as described in the Guidelines for Carcinogen Risk Assessment, was conducted to evaluate small intestinal tumors observed in mice chronically exposed to relatively high concentrations of hexavalent chromium (Cr(VI)) in drinking water. Based on review of the literature, key events in the MOA are hypothesized to include saturation of the reductive capacity of the upper gastrointestinal tract, absorption of Cr(VI) into the intestinal epithelium, oxidative stress and inflammation, cell proliferation, direct and/or indirect DNA modification, and mutagenesis. Although available data generally support the plausibility of these key events, several unresolved questions and data gaps were identified, highlighting the need for obtaining critical toxicokinetic and toxicodynamic data in the target tissue and in the low-dose range. Experimental assays that can address these data gaps are discussed along with strategies for comparisons between responsive and nonresponsive tissues and species. This analysis provides a practical application of MOA Framework guidance and is instructive for the design of studies to improve upon the information available for quantitative risk assessment."
670644,Rui et al. 2010,"Nickel, cobalt and chromate sensitization and occupation","BACKGROUND: Exposure to nickel, cobalt and chromate are important causes of occupational contact dermatitis. OBJECTIVES: To estimate the prevalence of nickel, cobalt and chromate allergy in a population of consecutive patients and to investigate the possible association with individual and occupational risk factors. PATIENTS/METHODS: A total of 14 464 patients (67.6% women and 32.4% men) with suspected allergic dermatitis underwent patch tests. The associations between patch test results and occupations were studied by multivariate logistic regression analysis. RESULTS: About 24.6% of the patients reacted positively to nickel sulphate, 10.2% to cobalt chloride and 8.7% to potassium dichromate. Nickel sensitization was higher in women aged 26-35 years in comparison with the youngest group (15-25 years) and the older group (> 45 years). In women, the prevalence of positive reactions to nickel was positively associated with metal and mechanical work (OR 1.54; 95%, CI 1.16-2.05). Chromate sensitization was more prevalent in building trade workers for both women (OR 1.58; 95% CI 1.00-2.49) and men (OR 2.24; 95% CI 1.55-3.22). Cobalt sensitization was associated with textile and leather work in women (OR 1.52; 95% CI 1.09-2.12) and with cleaning work in men (OR 1.86; 95% CI 1.18-2.93). CONCLUSIONS: Our study showed interesting associations between some occupations and nickel, chromate and cobalt allergy.","Nickel, cobalt and chromate sensitization and occupation Abs: BACKGROUND: Exposure to nickel, cobalt and chromate are important causes of occupational contact dermatitis. OBJECTIVES: To estimate the prevalence of nickel, cobalt and chromate allergy in a population of consecutive patients and to investigate the possible association with individual and occupational risk factors. PATIENTS/METHODS: A total of 14 464 patients (67.6% women and 32.4% men) with suspected allergic dermatitis underwent patch tests. The associations between patch test results and occupations were studied by multivariate logistic regression analysis. RESULTS: About 24.6% of the patients reacted positively to nickel sulphate, 10.2% to cobalt chloride and 8.7% to potassium dichromate. Nickel sensitization was higher in women aged 26-35 years in comparison with the youngest group (15-25 years) and the older group (> 45 years). In women, the prevalence of positive reactions to nickel was positively associated with metal and mechanical work (OR 1.54; 95%, CI 1.16-2.05). Chromate sensitization was more prevalent in building trade workers for both women (OR 1.58; 95% CI 1.00-2.49) and men (OR 2.24; 95% CI 1.55-3.22). Cobalt sensitization was associated with textile and leather work in women (OR 1.52; 95% CI 1.09-2.12) and with cleaning work in men (OR 1.86; 95% CI 1.18-2.93). CONCLUSIONS: Our study showed interesting associations between some occupations and nickel, chromate and cobalt allergy."
670625,Merritt et al. 1989,"Elimination of nickel, cobalt, and chromium following repeated injections of high dose metal salts","A study was conducted to determine the ability of hamsters to eliminate in the urine, or store in the organs, large quantities of metal salts given over a period of several months. In addition, the effect of prior immunization on metal ion clearance was determined. The results indicated that nickel was rapidly eliminated in the urine and that the level in the organs was similar to that of control animals. Cobalt was eliminated more slowly than was nickel. The organ levels of cobalt were similar to those of control animals with a slight elevation in the liver of the injected animals. Chromium was eliminated in the urine very slowly, was red cell associated, and the levels were elevated in all the organs (liver, lung, spleen, kidney) compared to control. Prior immunization with metal salts increased the storage of chromium.","Elimination of nickel, cobalt, and chromium following repeated injections of high dose metal salts Abs: A study was conducted to determine the ability of hamsters to eliminate in the urine, or store in the organs, large quantities of metal salts given over a period of several months. In addition, the effect of prior immunization on metal ion clearance was determined. The results indicated that nickel was rapidly eliminated in the urine and that the level in the organs was similar to that of control animals. Cobalt was eliminated more slowly than was nickel. The organ levels of cobalt were similar to those of control animals with a slight elevation in the liver of the injected animals. Chromium was eliminated in the urine very slowly, was red cell associated, and the levels were elevated in all the organs (liver, lung, spleen, kidney) compared to control. Prior immunization with metal salts increased the storage of chromium."
670615,Lazarov 2006,European Standard Series patch test results from a contact dermatitis clinic in Israel during the 7-year period from 1998 to 2004,"The results of a 7-year retrospective study (1998-2004) from patch testing with the European Standard Series (ESS) establishing the frequency of sensitization in a contact dermatitis clinic in Israel are presented. 23 allergens were patch tested on 2156 patients, 1462 females (67.8%) and 694 males (32.2%). Atopy and asthma were present in 21.9% of the patients. One or more allergic reactions were observed in 937 patients (43.5%). The highest yield of patch test positives from the 1076 positive reactions were obtained from nickel sulfate (13.9%), fragrance mix (7.1%), potassium dichromate (3.8%), Balsam of Peru (3.6%), CL+Me-isothiazolinone (3.4%) and cobalt chloride (3.4%). Allergens which produced the least amount of positive results were primin and clioquinol. Allergic contact dermatitis (ACD) was established in 32.8%, whereas occupationally related allergic (8.0) and irritant contact dermatitis (5.6%) affected a total of 13.6% of the cases studied. The most common clinical forms of dermatitis were chronic dermatitis (47.7%) followed by acute dermatitis (22.8%), and lichenification and hyperkeratosis (7.9%). The hands (30.7%), face and neck (23.9%) and extremities (11.3%) were the most frequently affected areas. Four allergens in our study differed from the top 10 allergens in Europe namely: Cl+Me-isothiazolinone, formaldehyde, 4-tert-butylphenol formaldehyde resin and sesquiterpene lactone mix reflecting an existing difference in environmental exposure. Our study is the first to provide data on the frequency of sensitization and important allergens in the aetiology of ACD in Israel. In spite of the existing differences with Europe, we conclude that ESS is an appropriate screening system for the diagnosis of ACD in Israel.","European Standard Series patch test results from a contact dermatitis clinic in Israel during the 7-year period from 1998 to 2004 Abs: The results of a 7-year retrospective study (1998-2004) from patch testing with the European Standard Series (ESS) establishing the frequency of sensitization in a contact dermatitis clinic in Israel are presented. 23 allergens were patch tested on 2156 patients, 1462 females (67.8%) and 694 males (32.2%). Atopy and asthma were present in 21.9% of the patients. One or more allergic reactions were observed in 937 patients (43.5%). The highest yield of patch test positives from the 1076 positive reactions were obtained from nickel sulfate (13.9%), fragrance mix (7.1%), potassium dichromate (3.8%), Balsam of Peru (3.6%), CL+Me-isothiazolinone (3.4%) and cobalt chloride (3.4%). Allergens which produced the least amount of positive results were primin and clioquinol. Allergic contact dermatitis (ACD) was established in 32.8%, whereas occupationally related allergic (8.0) and irritant contact dermatitis (5.6%) affected a total of 13.6% of the cases studied. The most common clinical forms of dermatitis were chronic dermatitis (47.7%) followed by acute dermatitis (22.8%), and lichenification and hyperkeratosis (7.9%). The hands (30.7%), face and neck (23.9%) and extremities (11.3%) were the most frequently affected areas. Four allergens in our study differed from the top 10 allergens in Europe namely: Cl+Me-isothiazolinone, formaldehyde, 4-tert-butylphenol formaldehyde resin and sesquiterpene lactone mix reflecting an existing difference in environmental exposure. Our study is the first to provide data on the frequency of sensitization and important allergens in the aetiology of ACD in Israel. In spite of the existing differences with Europe, we conclude that ESS is an appropriate screening system for the diagnosis of ACD in Israel."
670604,Keegan et al. 2008,"A systematic comparison of the actual, potential, and theoretical health effects of cobalt and chromium exposures from industry and surgical implants","Humans are exposed to cobalt (Co) and chromium (Cr) from industry and surgical devices, most notably orthopedic joint replacements. This review compares the potential health effects of exposure to Co and Cr contaminants from these two different sources, both in the locally exposed tissues and at sites distant to the primary exposure. Surgical implantation results largely in exposures to ions, corrosion products, and particles of Co and Cr. Industrial exposures are predominantly to metal compounds and particles. Although there are large literatures on industrial and surgical exposures to these metals, there has yet to be a systematic comparison of the two to test whether more general lessons might be learned about the human toxicology of Co and Cr. Both industrial and surgical exposures cause inflammatory and other immune reactions in the directly exposed tissues. In the lung there is a well-established risk of cancer following long-term exposures to hexavalent Cr; however, the development of sarcoma in the connective tissues adjacent to implants in response to metal particles is rare. Both types of exposure are associated with changes in the peripheral blood, including evidence of oxidative stress, and altered numbers of circulating immune cells. There is dissemination of Co and Cr to sites distant to the orthopedic implant, but less is known about systemic dissemination of these metals away from the lung. The effects of industrial exposures in the reproductive, renal, and cardiac systems have been investigated, but this has yet to be explored after surgical exposures. The form of the metal (and associated elements) in both instances is key to the toxicological effects arising in the body and further characterization of debris released from devices is certainly recommended, as is the impact of nanotoxicology on the health and safety of workers and patients. Biomonitoring schemes currently used in industry could be translated, if required, into suitable programs for orthopedic out-patients. Cross-communication between experts in industrial and occupational medicine and regulatory agencies may be useful.","A systematic comparison of the actual, potential, and theoretical health effects of cobalt and chromium exposures from industry and surgical implants Abs: Humans are exposed to cobalt (Co) and chromium (Cr) from industry and surgical devices, most notably orthopedic joint replacements. This review compares the potential health effects of exposure to Co and Cr contaminants from these two different sources, both in the locally exposed tissues and at sites distant to the primary exposure. Surgical implantation results largely in exposures to ions, corrosion products, and particles of Co and Cr. Industrial exposures are predominantly to metal compounds and particles. Although there are large literatures on industrial and surgical exposures to these metals, there has yet to be a systematic comparison of the two to test whether more general lessons might be learned about the human toxicology of Co and Cr. Both industrial and surgical exposures cause inflammatory and other immune reactions in the directly exposed tissues. In the lung there is a well-established risk of cancer following long-term exposures to hexavalent Cr; however, the development of sarcoma in the connective tissues adjacent to implants in response to metal particles is rare. Both types of exposure are associated with changes in the peripheral blood, including evidence of oxidative stress, and altered numbers of circulating immune cells. There is dissemination of Co and Cr to sites distant to the orthopedic implant, but less is known about systemic dissemination of these metals away from the lung. The effects of industrial exposures in the reproductive, renal, and cardiac systems have been investigated, but this has yet to be explored after surgical exposures. The form of the metal (and associated elements) in both instances is key to the toxicological effects arising in the body and further characterization of debris released from devices is certainly recommended, as is the impact of nanotoxicology on the health and safety of workers and patients. Biomonitoring schemes currently used in industry could be translated, if required, into suitable programs for orthopedic out-patients. Cross-communication between experts in industrial and occupational medicine and regulatory agencies may be useful."
670543,Akyol et al. 2005,Contact sensitivity to standard series allergens in 1038 patients with contact dermatitis in Turkey,"We planned to determine the frequency of sensitivity to European standard patch test allergens in 1038 patients with contact dermatitis. From 1992 to 2004, 1038 patients with the diagnosis of contact dermatitis were patch tested with the European standard series. Seven hundred and five patients were female (67.9%) and 333 patients were male (32.1%). A total of 336 patients (32.3%) had one or more positive patch test reactions. The most common allergens were nickel (17.6%), cobalt chloride (5.3%), potassium dichromate (4.6%), neomycin (2.4%), fragrance mix (2.1%) and balsam of Peru (2.1%). Contact sensitivity to potassium dichromate and thiuram was significantly more frequent in male patients, whereas nickel and primin sensitivity was significantly more frequent in female patients. Higher sensitivity rates for potassium dichromate, neomycin, balsam of Peru, wool alcohol, fragrance mix and primin were noted in patients over 40 years of age. Sensitivity rates of the standard series allergens were all similar in atopic patients and in non-atopic patients. Metals, neomycin and fragrances are the leading allergens in Turkey. Although fragrances are among the most important sensitizers, sensitivity rates to fragrances and also to preservatives are much lower than the rates in Europe and the US.","Contact sensitivity to standard series allergens in 1038 patients with contact dermatitis in Turkey Abs: We planned to determine the frequency of sensitivity to European standard patch test allergens in 1038 patients with contact dermatitis. From 1992 to 2004, 1038 patients with the diagnosis of contact dermatitis were patch tested with the European standard series. Seven hundred and five patients were female (67.9%) and 333 patients were male (32.1%). A total of 336 patients (32.3%) had one or more positive patch test reactions. The most common allergens were nickel (17.6%), cobalt chloride (5.3%), potassium dichromate (4.6%), neomycin (2.4%), fragrance mix (2.1%) and balsam of Peru (2.1%). Contact sensitivity to potassium dichromate and thiuram was significantly more frequent in male patients, whereas nickel and primin sensitivity was significantly more frequent in female patients. Higher sensitivity rates for potassium dichromate, neomycin, balsam of Peru, wool alcohol, fragrance mix and primin were noted in patients over 40 years of age. Sensitivity rates of the standard series allergens were all similar in atopic patients and in non-atopic patients. Metals, neomycin and fragrances are the leading allergens in Turkey. Although fragrances are among the most important sensitizers, sensitivity rates to fragrances and also to preservatives are much lower than the rates in Europe and the US."
670494,Kawanishi et al. 1994,Active oxygen species in DNA damage induced by carcinogenic metal compounds,"Some carcinogenic metal compounds [chromate(VI), Fe(III) nitrilotriacetate, cobalt(II), and nickel(II)[ induced formation of various oxygen radical species in the presence of hydrogen peroxide. These oxygen radicals were suggested to give different kinds of site-specific DNA damage; 8-hydroxyl-2'-deoxyguanosine formation is included in the DNA damage. Using pulsed-field gel electrophoresis, nickel sulfide was shown to induce oxidative DNA cleavage in cultured cells. On the basis of these findings, we have emphasized the role of oxygen radicals in metal carcinogenesis.","Active oxygen species in DNA damage induced by carcinogenic metal compounds Abs: Some carcinogenic metal compounds [chromate(VI), Fe(III) nitrilotriacetate, cobalt(II), and nickel(II)[ induced formation of various oxygen radical species in the presence of hydrogen peroxide. These oxygen radicals were suggested to give different kinds of site-specific DNA damage; 8-hydroxyl-2'-deoxyguanosine formation is included in the DNA damage. Using pulsed-field gel electrophoresis, nickel sulfide was shown to induce oxidative DNA cleavage in cultured cells. On the basis of these findings, we have emphasized the role of oxygen radicals in metal carcinogenesis."
669228,Tomasik and  Warren 1996,The use of daphnia in studies of metal pollution of aquatic systems,BIOSIS COPYRIGHT: BIOL ABS. RRM LITERATURE REVIEW DAPHNIA ECOTOXICOLOGY BIOINDICATOR,The use of daphnia in studies of metal pollution of aquatic systems Abs: BIOSIS COPYRIGHT: BIOL ABS. RRM LITERATURE REVIEW DAPHNIA ECOTOXICOLOGY BIOINDICATOR
668469,Tra et al. 1998,"Pollution of water and agricultural soils in Tuliem and Thanhtri districts of Hanoi City, Vietnam: A report","BIOSIS COPYRIGHT: BIOL ABS. Limited information is available on the quality of water and agricultural soils in Tuliem and Thanhtri districts of Hanoi city. Based on the Vietnam standard for the quality of water and soils, 14 water and 22 soil samples in Thanhtri district, and 7 water and 14 soil samples in Tuliem district were collected and analyzed for the prescribed parameters. In comparison with the Vietnam standard for the quality of water and soils, quality of water and soils in Tuliem and Thanhtri districts was evaluated. Quality of water as agricultural use was as follows: pH was neutral; EC was between 0.18 and 0.59 dS/m; COD was below the limit; no sample was over the limit value for Zn, but one, three and two samples exceeded the limit values for Cu, Pb and Cd, respectively. Quality of agricultural soils was as follows: pH ranged from 5.40 to 7.00; all soil samples showed total N content below 0.25% and available P2O5 more than 20 mg/kg; contamination of several heavy metals was indicate","Pollution of water and agricultural soils in Tuliem and Thanhtri districts of Hanoi City, Vietnam: A report Abs: BIOSIS COPYRIGHT: BIOL ABS. Limited information is available on the quality of water and agricultural soils in Tuliem and Thanhtri districts of Hanoi city. Based on the Vietnam standard for the quality of water and soils, 14 water and 22 soil samples in Thanhtri district, and 7 water and 14 soil samples in Tuliem district were collected and analyzed for the prescribed parameters. In comparison with the Vietnam standard for the quality of water and soils, quality of water and soils in Tuliem and Thanhtri districts was evaluated. Quality of water as agricultural use was as follows: pH was neutral; EC was between 0.18 and 0.59 dS/m; COD was below the limit; no sample was over the limit value for Zn, but one, three and two samples exceeded the limit values for Cu, Pb and Cd, respectively. Quality of agricultural soils was as follows: pH ranged from 5.40 to 7.00; all soil samples showed total N content below 0.25% and available P2O5 more than 20 mg/kg; contamination of several heavy metals was indicate"
668456,Templeton 1999,Biomedical aspects of trace element speciation,"BIOSIS COPYRIGHT: BIOL ABS. Speciation affects the bioavailability and toxicity of elements and so is important in toxicology and nutrition. Exploitation of speciation profiles in medical management is widely unexplored. Isotopic speciation in the body can also offer clues to sources of exposure. The redox state of some elements determines toxicity and affects transport across biological barriers. Distinguishing inorganic from organometallic forms of Hg, Pb, and Sn is important to assess exposure to the more toxic organome ult to define because of the complex composition of the biological fluid, including amino and other organic acids, and thiols. Albumin and/or transferrin dominate the macromolecular species of many essential and non-essential elements.","Biomedical aspects of trace element speciation Abs: BIOSIS COPYRIGHT: BIOL ABS. Speciation affects the bioavailability and toxicity of elements and so is important in toxicology and nutrition. Exploitation of speciation profiles in medical management is widely unexplored. Isotopic speciation in the body can also offer clues to sources of exposure. The redox state of some elements determines toxicity and affects transport across biological barriers. Distinguishing inorganic from organometallic forms of Hg, Pb, and Sn is important to assess exposure to the more toxic organome ult to define because of the complex composition of the biological fluid, including amino and other organic acids, and thiols. Albumin and/or transferrin dominate the macromolecular species of many essential and non-essential elements."
668225,Namiesnik and  Zygmunt 1999,Role of reference materials in analysis of environmental pollutants,"BIOSIS COPYRIGHT: BIOL ABS. This paper discusses the importance and use of reference materials for quality assurance and quality control in environmental analysis. The general classification of reference materials and categorisation of those for chemical composition are presented. The most common reference materials for pollutants in air, water, waste water, soil, sediments, sludge and some biological materials and their producers are tabulated. Definitions, practical recommendations on selection and handling, and applicat","Role of reference materials in analysis of environmental pollutants Abs: BIOSIS COPYRIGHT: BIOL ABS. This paper discusses the importance and use of reference materials for quality assurance and quality control in environmental analysis. The general classification of reference materials and categorisation of those for chemical composition are presented. The most common reference materials for pollutants in air, water, waste water, soil, sediments, sludge and some biological materials and their producers are tabulated. Definitions, practical recommendations on selection and handling, and applicat"
668112,Levina et al. 1999,In vitro plasmid DNA cleavage by chromium(V) and -(IV) 2-hydroxycarboxylato complexes,"The ability of relatively stable Cr(V) and Cr(IV) complexes with 2-hydroxycarboxylato ligands [2-ethyl-2-hydroxybutanoate(2-) = ehba; (1R,3R,4R,5R)-1,3,4,5-tetrahydroxycyclohexanecarboxylate(2-) = quinate = qa] to induce single-strand breaks in plasmid DNA has been studied under a wide range of reaction conditions. The Cr(V) complex, Na[CrVO(ehba)2], causes substantial DNA cleavage at pH 4.0-8.0 [[Cr(V)]0 = 0.010-0.75 mM, phosphate buffer, and 37 degrees C]. The DNA cleavage is inhibited by the presence of excess ligand, by exclusion of O2, or by addition of organic compounds, such as alcohols, carboxylic acids, or DMSO, but it is not affected by traces of catalytic metals [Fe(III) or Cu(II)] or by addition of catalase. The Cr(IV)-qa complexes, unlike the Cr(V) complexes, are able to cleave DNA in the presence of the ligand in a large excess [[Cr(IV)]0 = 0.50 mM, [qa] = 20-100 mM, pH 3.5-6.0, and 37 degrees C]. This is the first direct evidence for DNA cleavage induced by well-characterized Cr(IV) complexes. The proposed mechanism for DNA cleavage includes the following: (i) partial aquation of the bis-chelated Cr(V) and -(IV) complexes with the formation of reactive monochelated forms, (ii) binding of the Cr(V) and -(IV) monochelates to the phosphate backbone of DNA, (iii) one- or two-electron oxidations at the deoxyribose moieties of DNA by Cr(V) and -(IV), and (iv) cleavage of the resulting DNA radicals or cations with or without participation of O2. The patterns of DNA damage by Cr(V) and -(IV) can include strand breaks, generation of abasic sites, and the formation of Cr(III)-DNA complexes.","In vitro plasmid DNA cleavage by chromium(V) and -(IV) 2-hydroxycarboxylato complexes Abs: The ability of relatively stable Cr(V) and Cr(IV) complexes with 2-hydroxycarboxylato ligands [2-ethyl-2-hydroxybutanoate(2-) = ehba; (1R,3R,4R,5R)-1,3,4,5-tetrahydroxycyclohexanecarboxylate(2-) = quinate = qa] to induce single-strand breaks in plasmid DNA has been studied under a wide range of reaction conditions. The Cr(V) complex, Na[CrVO(ehba)2], causes substantial DNA cleavage at pH 4.0-8.0 [[Cr(V)]0 = 0.010-0.75 mM, phosphate buffer, and 37 degrees C]. The DNA cleavage is inhibited by the presence of excess ligand, by exclusion of O2, or by addition of organic compounds, such as alcohols, carboxylic acids, or DMSO, but it is not affected by traces of catalytic metals [Fe(III) or Cu(II)] or by addition of catalase. The Cr(IV)-qa complexes, unlike the Cr(V) complexes, are able to cleave DNA in the presence of the ligand in a large excess [[Cr(IV)]0 = 0.50 mM, [qa] = 20-100 mM, pH 3.5-6.0, and 37 degrees C]. This is the first direct evidence for DNA cleavage induced by well-characterized Cr(IV) complexes. The proposed mechanism for DNA cleavage includes the following: (i) partial aquation of the bis-chelated Cr(V) and -(IV) complexes with the formation of reactive monochelated forms, (ii) binding of the Cr(V) and -(IV) monochelates to the phosphate backbone of DNA, (iii) one- or two-electron oxidations at the deoxyribose moieties of DNA by Cr(V) and -(IV), and (iv) cleavage of the resulting DNA radicals or cations with or without participation of O2. The patterns of DNA damage by Cr(V) and -(IV) can include strand breaks, generation of abasic sites, and the formation of Cr(III)-DNA complexes."
667949,Hachimi et al. 1998,"Speciation of chromium, lead and nickel compounds by laser microprobe mass spectrometry and application to environmental and biological samples","BIOSIS COPYRIGHT: BIOL ABS. Laser microprobe mass spectrometry with time-of-flight analyser is evaluated as a tool to perform speciation of chromium, nickel and lead compounds in solids with a lateral resolution in the mu range. Commercial instruments irradiate the sample at 266 nm while a tunable dye laser is fitted to some experimental set-ups. The analytical merits of both approaches are surveyed and their application to selected test cases in the field of environment and biological tissue analysis at the sub-cellular level is presented. A comparison between TOF LMMS and mu-Raman for the speciation of given components in large industrial airbone particles is discussed.","Speciation of chromium, lead and nickel compounds by laser microprobe mass spectrometry and application to environmental and biological samples Abs: BIOSIS COPYRIGHT: BIOL ABS. Laser microprobe mass spectrometry with time-of-flight analyser is evaluated as a tool to perform speciation of chromium, nickel and lead compounds in solids with a lateral resolution in the mu range. Commercial instruments irradiate the sample at 266 nm while a tunable dye laser is fitted to some experimental set-ups. The analytical merits of both approaches are surveyed and their application to selected test cases in the field of environment and biological tissue analysis at the sub-cellular level is presented. A comparison between TOF LMMS and mu-Raman for the speciation of given components in large industrial airbone particles is discussed."
667943,Guilhermino et al. 1998,Should the use of inhibition of cholinesterases as a specific biomarker for organophosphate and carbamate pesticides be questioned?,"BIOSIS COPYRIGHT: BIOL ABS. Recently there has been evidence that contaminants other than organophosphate and carbamate pesticides may inhibit the activity of the enzyme acetylcholinesterase (AChE) both under in vitro and in vivo conditions. In this study we investigated the in vitro effect of three detergents (dodecyl benzyl sulphonate (DBS), sodium dodecyl sulphate (SDS) and a mixture commonly used as domestic detergent (X)) and three metals (molybdenum, barium and chromium (VI)) on AChE activity of Mytilus galloprovincialis haemolymph. All the detergents tested significantly inhibited the activity of the enzyme. The lowest observed effect concentrations were equal to 12.5 for DBS and 50 mg l-1 for SDS and X. Among the metals, molybdenum and barium had no effect on AChE activity, whereas chromium (VI) significantly depressed the activity of the enzyme at concentrations equal to or higher than 25 mg l-1. These results suggest that the use of AChE as a specific biomarker for organophosphate and c","Should the use of inhibition of cholinesterases as a specific biomarker for organophosphate and carbamate pesticides be questioned? Abs: BIOSIS COPYRIGHT: BIOL ABS. Recently there has been evidence that contaminants other than organophosphate and carbamate pesticides may inhibit the activity of the enzyme acetylcholinesterase (AChE) both under in vitro and in vivo conditions. In this study we investigated the in vitro effect of three detergents (dodecyl benzyl sulphonate (DBS), sodium dodecyl sulphate (SDS) and a mixture commonly used as domestic detergent (X)) and three metals (molybdenum, barium and chromium (VI)) on AChE activity of Mytilus galloprovincialis haemolymph. All the detergents tested significantly inhibited the activity of the enzyme. The lowest observed effect concentrations were equal to 12.5 for DBS and 50 mg l-1 for SDS and X. Among the metals, molybdenum and barium had no effect on AChE activity, whereas chromium (VI) significantly depressed the activity of the enzyme at concentrations equal to or higher than 25 mg l-1. These results suggest that the use of AChE as a specific biomarker for organophosphate and c"
667709,Miller et al. 2010,Characterizing exposures to airborne metals and nanoparticle emissions in a refinery,"An air quality survey was conducted at a precious metals refinery in order to evaluate worker exposures to airborne metals and to provide detailed characterization of the aerosols. Two areas within the refinery were characterized: a furnace room and an electro-refining area. In line with standard survey practices, both personal and area air filter samples were collected on 37-mm filters and analyzed for metals by inductively coupled plasma–atomic emission spectroscopy. In addition to the standard sampling, measurements were conducted using other tools, designed to provide enhanced characterization of the workplace aerosols. The number concentration and number-weighted particle size distribution of airborne particles were measured with a fast mobility particle sizer (FMPS). Custom-designed software was used to correlate particle concentration data with spatial location data to generate contour maps of particle number concentrations in the work areas. Short-term samples were collected in areas of localized high concentrations and analyzed using transmission electron microscopy (TEM) and energy dispersive spectroscopy (EDS) to determine particle morphology and elemental chemistry. Analysis of filter samples indicated that all of the workers were exposed to levels of silver above the Occupational Safety and Health Administration permissible exposure limit of 0.01 mg m?3 even though the localized ventilation was functioning. Measurements with the FMPS indicated that particle number concentrations near the furnace increased up to 1000-fold above the baseline during the pouring of molten metal. Spatial mapping revealed localized elevated particle concentrations near the furnaces and plumes of particles rising into the stairwells and traveling to the upper work areas. Results of TEM/EDS analyses confirmed the high number of nanoparticles measured by the FMPS and indicated the aerosols were rich in metals including silver, lead, antimony, selenium, and zinc. Results of the survey were used to deduce appropriate strategies for mitigation of worker exposure to airborne metals.","Characterizing exposures to airborne metals and nanoparticle emissions in a refinery Abs: An air quality survey was conducted at a precious metals refinery in order to evaluate worker exposures to airborne metals and to provide detailed characterization of the aerosols. Two areas within the refinery were characterized: a furnace room and an electro-refining area. In line with standard survey practices, both personal and area air filter samples were collected on 37-mm filters and analyzed for metals by inductively coupled plasma–atomic emission spectroscopy. In addition to the standard sampling, measurements were conducted using other tools, designed to provide enhanced characterization of the workplace aerosols. The number concentration and number-weighted particle size distribution of airborne particles were measured with a fast mobility particle sizer (FMPS). Custom-designed software was used to correlate particle concentration data with spatial location data to generate contour maps of particle number concentrations in the work areas. Short-term samples were collected in areas of localized high concentrations and analyzed using transmission electron microscopy (TEM) and energy dispersive spectroscopy (EDS) to determine particle morphology and elemental chemistry. Analysis of filter samples indicated that all of the workers were exposed to levels of silver above the Occupational Safety and Health Administration permissible exposure limit of 0.01 mg m?3 even though the localized ventilation was functioning. Measurements with the FMPS indicated that particle number concentrations near the furnace increased up to 1000-fold above the baseline during the pouring of molten metal. Spatial mapping revealed localized elevated particle concentrations near the furnaces and plumes of particles rising into the stairwells and traveling to the upper work areas. Results of TEM/EDS analyses confirmed the high number of nanoparticles measured by the FMPS and indicated the aerosols were rich in metals including silver, lead, antimony, selenium, and zinc. Results of the survey were used to deduce appropriate strategies for mitigation of worker exposure to airborne metals."
666747,Loscutoff and  Poore 1993,Ambient air toxics data from California's toxic air contaminant monitoring program,Biosis copyright: biol abs. rrm meeting paper book chapter air pollution seasonality usa,Ambient air toxics data from California's toxic air contaminant monitoring program Abs: Biosis copyright: biol abs. rrm meeting paper book chapter air pollution seasonality usa
665479,Fernandez-Sempere et al. 1997,Characterization of tannery wastes: Comparison of three leachability tests,"BIOSIS COPYRIGHT: BIOL ABS. 12 samples from different tanning industries and corresponding to leather wastes and semi-processed leather trimmings and shavings have been characterized. The characterization includes the determination of moisture level, reactivity, analysis of dry sample, analysis of the effluent from the leachability test and toxicity test with Photobacterium phosphoreum and Daphnia magna. The leachability of Cr, Zn, Pb, Cd, Ni, Cu, Ba and phenolic compounds was evaluated by three different methods: the extraction procedure (EP) according to the Spanish legislation (very similar to the EP test from USEPA), the extraction procedure from the EEC proposal of Directive and the toxicity characteristic leaching procedure (TCLP) from the USEPA.","Characterization of tannery wastes: Comparison of three leachability tests Abs: BIOSIS COPYRIGHT: BIOL ABS. 12 samples from different tanning industries and corresponding to leather wastes and semi-processed leather trimmings and shavings have been characterized. The characterization includes the determination of moisture level, reactivity, analysis of dry sample, analysis of the effluent from the leachability test and toxicity test with Photobacterium phosphoreum and Daphnia magna. The leachability of Cr, Zn, Pb, Cd, Ni, Cu, Ba and phenolic compounds was evaluated by three different methods: the extraction procedure (EP) according to the Spanish legislation (very similar to the EP test from USEPA), the extraction procedure from the EEC proposal of Directive and the toxicity characteristic leaching procedure (TCLP) from the USEPA."
665378,Hoekstra et al. 1994,Variation in the Sensitivity of Aquatic Species to Toxicants,BIOSIS COPYRIGHT: BIOL ABS. RRM RESEARCH ARTICLE 1 HYDROZOA 2 STELLEROIDEA 8 BIVALVIA 14 GASTROPODA 3 TURBELLARIA 2 DIGONONTA 2 MONOGONONTA 2 HIRUDINEA 5 OLIGOCHAETA 6 POLYCHAETA 34 MALACOSTRACA 12 MAXILLOPODA 12 PHYLLOPODA 41 INSECTA 5 AMPHIBIA 47 OSTEICHTHYES 196 SPECIES 26 CHEMICALS PESTICIDE METAL ECOSYSTEM HAZARD ASSESSMENT SPECIES SENSITIVITY TAXONOMIC CLASSIFICATION RELATIONSHIP,Variation in the Sensitivity of Aquatic Species to Toxicants Abs: BIOSIS COPYRIGHT: BIOL ABS. RRM RESEARCH ARTICLE 1 HYDROZOA 2 STELLEROIDEA 8 BIVALVIA 14 GASTROPODA 3 TURBELLARIA 2 DIGONONTA 2 MONOGONONTA 2 HIRUDINEA 5 OLIGOCHAETA 6 POLYCHAETA 34 MALACOSTRACA 12 MAXILLOPODA 12 PHYLLOPODA 41 INSECTA 5 AMPHIBIA 47 OSTEICHTHYES 196 SPECIES 26 CHEMICALS PESTICIDE METAL ECOSYSTEM HAZARD ASSESSMENT SPECIES SENSITIVITY TAXONOMIC CLASSIFICATION RELATIONSHIP
665017,Kauppinen et al. 1997,"International data base of exposure measurements in the pulp, paper and paper product industries","An international data base of exposure measurements in the pulp, paper and paper product industries was constructed to be used in exposure assessment for epidemiology studies and hazard control. Industrial hygiene and biological monitoring data were collected from countries participating in the multicentric study of the International Agency for Research on Cancer. Each measurement was characterized by country, mill type and number, department, job, agent measured, sampling method, measurement result in the standard unit, duration and date of sampling, assessment of representativeness, measurer, purpose of measurements, and remarks (e.g. on measurement sites and biases). Over 31,000 measurement results on 246 different chemical agents from 13 countries were available from pulp (45% of measurements), paper/paperboard/recycling (12%) and paper product (11%) mills or from their non-production departments (23%). Most measurements (82%) were carried out after 1980. The most frequently measured group of agents was inorganic gases (35%), followed by organic compounds (25%), solvents (18%), mineral dusts (12%), metals (6%) and bioaerosols (3%). Over 90% of the measurements were without an obvious bias, but their true representativeness is difficult to assess. Concentrations of various agents, including sulfur dioxide, chlorine dioxide, carbon monoxide, nitrogen dioxide, ozone, ammonia, formaldehyde and some solvents, often exceeded current occupational exposure limits. This data base summarizes a great deal of previously unpublished exposure data, provides a unique opportunity to study exposure patterns at the international level and identifies exposure situations that require further attention and investigation.","International data base of exposure measurements in the pulp, paper and paper product industries Abs: An international data base of exposure measurements in the pulp, paper and paper product industries was constructed to be used in exposure assessment for epidemiology studies and hazard control. Industrial hygiene and biological monitoring data were collected from countries participating in the multicentric study of the International Agency for Research on Cancer. Each measurement was characterized by country, mill type and number, department, job, agent measured, sampling method, measurement result in the standard unit, duration and date of sampling, assessment of representativeness, measurer, purpose of measurements, and remarks (e.g. on measurement sites and biases). Over 31,000 measurement results on 246 different chemical agents from 13 countries were available from pulp (45% of measurements), paper/paperboard/recycling (12%) and paper product (11%) mills or from their non-production departments (23%). Most measurements (82%) were carried out after 1980. The most frequently measured group of agents was inorganic gases (35%), followed by organic compounds (25%), solvents (18%), mineral dusts (12%), metals (6%) and bioaerosols (3%). Over 90% of the measurements were without an obvious bias, but their true representativeness is difficult to assess. Concentrations of various agents, including sulfur dioxide, chlorine dioxide, carbon monoxide, nitrogen dioxide, ozone, ammonia, formaldehyde and some solvents, often exceeded current occupational exposure limits. This data base summarizes a great deal of previously unpublished exposure data, provides a unique opportunity to study exposure patterns at the international level and identifies exposure situations that require further attention and investigation."
664815,Cornelis et al. 1997,"International Union of Pure and Applied Chemistry Clinical Chemistry Division, Commission on Toxicology (C-TOX)1, Commission on Nomenclature, Properties and Units (C-NPU)2 and International Federation of Clinical Chemistry, Scientific Division Committee on Nomenclature, Properties and Units (C-NPU)2 Properties and Units in the Clinical Laboratory Sciences. IX. Properties and Units in Trace Elements (IUPAC-IFCC Technical report 1997)","BIOSIS COPYRIGHT: BIOL ABS. This document is the first recommendation on the presentation of trace elements and their values in clinical laboratory sciences from IFCC and IUPAC. It forms part of the ongoing effort to standardize requests and reporting of laboratory data for transmission across cultural and linguistic domains, without attempting to standardize the language used by clinicians and laboratory practitioners. Subsequent documents deal with syntax, kinds-of-property, and properties and units used in other areas of clinical laboratory sciences.","International Union of Pure and Applied Chemistry Clinical Chemistry Division, Commission on Toxicology (C-TOX)1, Commission on Nomenclature, Properties and Units (C-NPU)2 and International Federation of Clinical Chemistry, Scientific Division Committee on Nomenclature, Properties and Units (C-NPU)2 Properties and Units in the Clinical Laboratory Sciences. IX. Properties and Units in Trace Elements (IUPAC-IFCC Technical report 1997) Abs: BIOSIS COPYRIGHT: BIOL ABS. This document is the first recommendation on the presentation of trace elements and their values in clinical laboratory sciences from IFCC and IUPAC. It forms part of the ongoing effort to standardize requests and reporting of laboratory data for transmission across cultural and linguistic domains, without attempting to standardize the language used by clinicians and laboratory practitioners. Subsequent documents deal with syntax, kinds-of-property, and properties and units used in other areas of clinical laboratory sciences."
664739,Boscolo et al. 1997,Effects of chromium on lymphocyte subsets and immunoglobulins from normal population and exposed workers,"Blood lymphocyte subsets and serum immunoglobulins were studied in 15 men (mean age: 35 years), not exposed to toxic agents, and in 15 healthy men, exposed to dust containing several compounds (including lead chromate), working in a factory producing plastic materials. Worker blood lead and urine chromium (Cr) levels were significantly higher than controls, while serum Cr concentration was unchanged. In the worker blood, CD4+ helper-inducer (mainly CD4+-CD45RO- “virgin”), CD5--CD19+ B, CD3--CD25+ activated B and CD3--HLA-DR+ activated B and natural killer (NK) lymphocytes were significantly reduced (about 30–50 %). The investigated workers were exposed to hexavalent Cr, as lead chromate, whereas normal population (control group) was mainly exposed to trivalent Cr. In the control group, urinary Cr showed a significant positive correlation with CD16+-56+ NK, CD5+-CD19+ B and HLA-DR+ activated T, B and NK lymphocytes and a negative correlation with serum IgA immunoglobuins; moreover, serum Cr was significantly correlated with all blood lymphocytes and HLA-DR+, CD3--HLA--DR+ and CD3--CD25+ lymphocyte subsets. These data suggest that trivalent Cr may be involved in mechanisms regulating the immune response in humans.","Effects of chromium on lymphocyte subsets and immunoglobulins from normal population and exposed workers Abs: Blood lymphocyte subsets and serum immunoglobulins were studied in 15 men (mean age: 35 years), not exposed to toxic agents, and in 15 healthy men, exposed to dust containing several compounds (including lead chromate), working in a factory producing plastic materials. Worker blood lead and urine chromium (Cr) levels were significantly higher than controls, while serum Cr concentration was unchanged. In the worker blood, CD4+ helper-inducer (mainly CD4+-CD45RO- “virgin”), CD5--CD19+ B, CD3--CD25+ activated B and CD3--HLA-DR+ activated B and natural killer (NK) lymphocytes were significantly reduced (about 30–50 %). The investigated workers were exposed to hexavalent Cr, as lead chromate, whereas normal population (control group) was mainly exposed to trivalent Cr. In the control group, urinary Cr showed a significant positive correlation with CD16+-56+ NK, CD5+-CD19+ B and HLA-DR+ activated T, B and NK lymphocytes and a negative correlation with serum IgA immunoglobuins; moreover, serum Cr was significantly correlated with all blood lymphocytes and HLA-DR+, CD3--HLA--DR+ and CD3--CD25+ lymphocyte subsets. These data suggest that trivalent Cr may be involved in mechanisms regulating the immune response in humans."
664319,Milner et al. 1996,Chemical Injury,Biosis copyright: biol abs. rrm book chapter human chemical burn,Chemical Injury Abs: Biosis copyright: biol abs. rrm book chapter human chemical burn
664318,Mccray 2001,Nonmetals Test and Evaluation: Delivery Order 0007: The Development of On-Aircraft Surface Preparations Utilizing Sol-Gel Coatings for Adhesive Bonding Aluminum Alloys,"Final rept. 1 Jan 1998-30 May 2001. High-performance surface preparations for adhesive bonding of metals typically require the use of strong acids or bases, volatile organic compounds (VOCs), and hexavalent chromium. Surface preparations used for on-aircraft repair of aluminum rely on hazardous materials or inconvenient processing steps, or they do not yield adequate bond performance. Grit-blast/silane (GBS)', phosphoric acid containment system (PACS)2, which is a version of phosphoric acid anodize (PAA)3, and certain acid paste etches are the high-performance surface treatments currently available for on-aircraft application. All are used in conjunction with chromated, high- VOC primers. All are time consuming for on- aircraft repair. Furthermore,, their use is becoming more difficult due to existing and proposed environmental, safety, and health regulations.","Nonmetals Test and Evaluation: Delivery Order 0007: The Development of On-Aircraft Surface Preparations Utilizing Sol-Gel Coatings for Adhesive Bonding Aluminum Alloys Abs: Final rept. 1 Jan 1998-30 May 2001. High-performance surface preparations for adhesive bonding of metals typically require the use of strong acids or bases, volatile organic compounds (VOCs), and hexavalent chromium. Surface preparations used for on-aircraft repair of aluminum rely on hazardous materials or inconvenient processing steps, or they do not yield adequate bond performance. Grit-blast/silane (GBS)', phosphoric acid containment system (PACS)2, which is a version of phosphoric acid anodize (PAA)3, and certain acid paste etches are the high-performance surface treatments currently available for on-aircraft application. All are used in conjunction with chromated, high- VOC primers. All are time consuming for on- aircraft repair. Furthermore,, their use is becoming more difficult due to existing and proposed environmental, safety, and health regulations."
664086,Sankararamakrishnan et al. 2006,Removal of hexavalent chromium using a novel cross linked xanthated chitosan,"Suitability of a novel cross linked, chemically modified chitosan as highly efficient adsorbent for the recovery of toxic chromium(VI) was studied. After cross linking with glutaraldehyde, xanthate group was grafted onto the back bone of chitosan. Sorption was found to be both pH and concentration dependent, with pH 3 being the optimum value. Both, chemically modified beads (CMCB) and flakes (CMCF) followed a pseudo-second-order kinetics with a rate constant of 2.037 and 4.639 g/mg/min, respectively. The equilibrium data followed the Langmuir isotherm model with maximum capacities of 625 mg/g and 256.4 mg/g and for CMCF and CMCB respectively. Desorption studies revealed the reusability of the sorbent for at least 10 cycles without any significant change in adsorption capacities.","Removal of hexavalent chromium using a novel cross linked xanthated chitosan Abs: Suitability of a novel cross linked, chemically modified chitosan as highly efficient adsorbent for the recovery of toxic chromium(VI) was studied. After cross linking with glutaraldehyde, xanthate group was grafted onto the back bone of chitosan. Sorption was found to be both pH and concentration dependent, with pH 3 being the optimum value. Both, chemically modified beads (CMCB) and flakes (CMCF) followed a pseudo-second-order kinetics with a rate constant of 2.037 and 4.639 g/mg/min, respectively. The equilibrium data followed the Langmuir isotherm model with maximum capacities of 625 mg/g and 256.4 mg/g and for CMCF and CMCB respectively. Desorption studies revealed the reusability of the sorbent for at least 10 cycles without any significant change in adsorption capacities."
663851,Chopwdhury 2003,Effect of industrial chemicals on male reproductive organ,"Exposure to industrial chemicals like lead, mercury, selenium, chromium, benzene hexachloride cyclohexane, formaldehyde, chlordecone, carbon disulphide, vinyl chloride and many others adversely affect male reproductive function. Lead exposure causes sperm tail abnormalities. Semen lead concentration was correspondingly increased with blood lead levels in those subjects who were exposed to lead 6 h daily over an average period of 6 years. Mercury affects the process of steroidogenesis and reduces testosterone blood levels. Exposure to selenium dioxide causes significant alterations in sperm morphology. Stainless steel workers exposed to the fumes of hexavalent chromium suffer an increased risk of reduced sperm quality and count. Benzene hexachloride cyclohexane (BHC), the cheapest insecticide, is a potent male gonadotoxic agent. The industrial exposure to formaldehyde of male workers causes the diminution of steroidogenesis. Dibromochloropropane (DBCP), a fumigant against nematodes, causes infertility in male workers. Chlordecone, a highly stable chlorinated hydrocarbon pesticide, causes oligospermia and reduction in motility. Exposure to carbon disulphide causes androgenic deficiency. Vinyl chloride monomer, a plasticiser, showed wide ranging sperm abnormalities. The toxic insult of these chemicals on male gametogenic and non-gametogenic cells may be due to sperm protein damage, oxidative damage to sperm head DNA and nuclear protein or oxidative damage of sperm by ROS. Germinal cell injury due to exposure of chemicals involves the interaction of androgen binding protein-heat shock protein 27 (ABP-hsp 27) and protein kinase (PKA)","Effect of industrial chemicals on male reproductive organ Abs: Exposure to industrial chemicals like lead, mercury, selenium, chromium, benzene hexachloride cyclohexane, formaldehyde, chlordecone, carbon disulphide, vinyl chloride and many others adversely affect male reproductive function. Lead exposure causes sperm tail abnormalities. Semen lead concentration was correspondingly increased with blood lead levels in those subjects who were exposed to lead 6 h daily over an average period of 6 years. Mercury affects the process of steroidogenesis and reduces testosterone blood levels. Exposure to selenium dioxide causes significant alterations in sperm morphology. Stainless steel workers exposed to the fumes of hexavalent chromium suffer an increased risk of reduced sperm quality and count. Benzene hexachloride cyclohexane (BHC), the cheapest insecticide, is a potent male gonadotoxic agent. The industrial exposure to formaldehyde of male workers causes the diminution of steroidogenesis. Dibromochloropropane (DBCP), a fumigant against nematodes, causes infertility in male workers. Chlordecone, a highly stable chlorinated hydrocarbon pesticide, causes oligospermia and reduction in motility. Exposure to carbon disulphide causes androgenic deficiency. Vinyl chloride monomer, a plasticiser, showed wide ranging sperm abnormalities. The toxic insult of these chemicals on male gametogenic and non-gametogenic cells may be due to sperm protein damage, oxidative damage to sperm head DNA and nuclear protein or oxidative damage of sperm by ROS. Germinal cell injury due to exposure of chemicals involves the interaction of androgen binding protein-heat shock protein 27 (ABP-hsp 27) and protein kinase (PKA)"
661946,Gonzalez et al. 1995,Gastrointestinal absorption of inorganic arsenic (V): The effect of concentration and interactions with phosphate and dichromate,"The absorption of inorganic pentavalent arsenic (As) by the rat small intestine was investigated using 2 different procedures: In vivo determination of overall extent of gastrointestinal absorption; and an intestinal perfusion technique. The aim was to determine the effect of concentration and the interaction with phosphate and dichromate anions on gastrointestinal absorption of As to understand the mechanism of As absorption at intestinal level. The results indicate there is a direct relationship, although not proportional, between the received dose and the absorbed amount of As. Intestinal absorption of As appears carried out by a saturable transport process. The phosphate produces a pronounced decrease in the intestinal absorption of As due to the fact that phosphate and As can share the same transport mechanism which is an active secondary carrier-mediated system depending on Na+ and H+ gradient. Addition of dichromate to perfusion buffers significantly (p > 0.05) increased As absorption. Several hypothesis may explain this fact: Dichromate produces pH modifications at the intracellular level, providing an adequate H(+)-gradient for As absorption; dichromate exerts a caustic effect, which damages the intestinal wall at the microvilli level. This allows free diffusion of As through the resulting openings.","Gastrointestinal absorption of inorganic arsenic (V): The effect of concentration and interactions with phosphate and dichromate Abs: The absorption of inorganic pentavalent arsenic (As) by the rat small intestine was investigated using 2 different procedures: In vivo determination of overall extent of gastrointestinal absorption; and an intestinal perfusion technique. The aim was to determine the effect of concentration and the interaction with phosphate and dichromate anions on gastrointestinal absorption of As to understand the mechanism of As absorption at intestinal level. The results indicate there is a direct relationship, although not proportional, between the received dose and the absorbed amount of As. Intestinal absorption of As appears carried out by a saturable transport process. The phosphate produces a pronounced decrease in the intestinal absorption of As due to the fact that phosphate and As can share the same transport mechanism which is an active secondary carrier-mediated system depending on Na+ and H+ gradient. Addition of dichromate to perfusion buffers significantly (p > 0.05) increased As absorption. Several hypothesis may explain this fact: Dichromate produces pH modifications at the intracellular level, providing an adequate H(+)-gradient for As absorption; dichromate exerts a caustic effect, which damages the intestinal wall at the microvilli level. This allows free diffusion of As through the resulting openings."
661838,Paxman and  Robinson 1990,Regulation of occupational carcinogens under OSHA's air contaminants standard,"BIOSIS COPYRIGHT: BIOL ABS. We compare the information used by the Occupational Safety and Health Administration (OSHA) to regulate carcinogens under its 1989 Air Contaminants Standard to publicity available information on substances with potential carcinogenic activity. Carcinogenicity evaluations were obtained from the National Institute for Occupational Safety and Health (NIOSH), the American Conference of Governmental Industrial Hygienists (ACGIH), the National Toxicology Program (NTP), the Environmental Protection Agency (EPA), and the International Agency for Research on Cancer (IARC). We focus on three sets of substances: those which we regulated as carcinogens by OSHA in the Standard, those which were included in the Standard but whose exposure limits are based on noncarcinogenic effects, and those substances designated as potential carcinogens by NIOSH, ACGIH, and/or NTP but which were excluded from the Standard. The data indicate that OSHA relied almost exlcusively upon the recommendation","Regulation of occupational carcinogens under OSHA's air contaminants standard Abs: BIOSIS COPYRIGHT: BIOL ABS. We compare the information used by the Occupational Safety and Health Administration (OSHA) to regulate carcinogens under its 1989 Air Contaminants Standard to publicity available information on substances with potential carcinogenic activity. Carcinogenicity evaluations were obtained from the National Institute for Occupational Safety and Health (NIOSH), the American Conference of Governmental Industrial Hygienists (ACGIH), the National Toxicology Program (NTP), the Environmental Protection Agency (EPA), and the International Agency for Research on Cancer (IARC). We focus on three sets of substances: those which we regulated as carcinogens by OSHA in the Standard, those which were included in the Standard but whose exposure limits are based on noncarcinogenic effects, and those substances designated as potential carcinogens by NIOSH, ACGIH, and/or NTP but which were excluded from the Standard. The data indicate that OSHA relied almost exlcusively upon the recommendation"
660865,Lewalter and  Miksche 1991,Individual variation and immunological effects in human biomonitoring,"The contribution of individual enzymatic and/or immunological factors to the metabolism and toxic effects of chemical agents was examined by evaluating case reports of exposures to aromatic amines, chlorinated aromatic hydrocarbons, and hexavalent chromium (7440473) compounds. Studies have suggested an association between the activity of N-acetyl-transferase enzymes and the ability to detoxify aromatic amines. The acetylation status of workers exposed to agents such as benzidine (92875), beta-naphthylamine (91598), or 4-aminodiphenyl (92671) has been reported to be related to risk of tumor development. In addition, the risk of formation of conjugates between aromatic amines and proteins such as hemoglobin has been associated with the acetylation status as well as the immunologic susceptibility of an individual. An enzymatic polymorphism in oxidative liver metabolism has been postulated to affect the degree of detoxification of reactive intermediates resulting from the metabolism of chlorobenzene (108907). Additionally, the reduction capacity of plasma has been implicated in influencing the chromium concentration in different blood compartments. Human chromium-VI metabolism has been reported to be dependent upon the ascorbic-acid and sulfhydryl group activities present in plasma or erythrocytes. Metabolic intermediates of certain chemical agents have been reported to affect the status of lymphocytes, the proliferation rate of which has been associated with protein adduct formation. Adduct formation rate was therefore proposed as a possible means of evaluation of the immune consequences of chemical exposure. The contribution of confounding factors such as diet and lifestyle habits was discussed.","Individual variation and immunological effects in human biomonitoring Abs: The contribution of individual enzymatic and/or immunological factors to the metabolism and toxic effects of chemical agents was examined by evaluating case reports of exposures to aromatic amines, chlorinated aromatic hydrocarbons, and hexavalent chromium (7440473) compounds. Studies have suggested an association between the activity of N-acetyl-transferase enzymes and the ability to detoxify aromatic amines. The acetylation status of workers exposed to agents such as benzidine (92875), beta-naphthylamine (91598), or 4-aminodiphenyl (92671) has been reported to be related to risk of tumor development. In addition, the risk of formation of conjugates between aromatic amines and proteins such as hemoglobin has been associated with the acetylation status as well as the immunologic susceptibility of an individual. An enzymatic polymorphism in oxidative liver metabolism has been postulated to affect the degree of detoxification of reactive intermediates resulting from the metabolism of chlorobenzene (108907). Additionally, the reduction capacity of plasma has been implicated in influencing the chromium concentration in different blood compartments. Human chromium-VI metabolism has been reported to be dependent upon the ascorbic-acid and sulfhydryl group activities present in plasma or erythrocytes. Metabolic intermediates of certain chemical agents have been reported to affect the status of lymphocytes, the proliferation rate of which has been associated with protein adduct formation. Adduct formation rate was therefore proposed as a possible means of evaluation of the immune consequences of chemical exposure. The contribution of confounding factors such as diet and lifestyle habits was discussed."
660818,Hooper et al. 1992,Regulation of priority carcinogens and reproductive or developmental toxicants,"In California, 370 carcinogens and 112 reproductive/developmental toxicants have been identified as a result of the State's Safe Drinking Water and Toxic Enforcement Act of 1986. They include pesticides, solvents, metals, industrial intermediates, environmental mixtures, and reactive agents. Occupational, environmental, and consumer product exposures that involve these agents are regulated under the Act. At levels of concern, businesses must provide warnings for and limit discharges of those chemicals. The lists of chemicals were compiled following systematic review of published data, including technical reports from the U.S. Public Health Service--National Toxicology Program (NTP), and evaluation of recommendations from authoritative bodies such as the International Agency for Research on Cancer (IARC) and the U.S. Environmental Protection Agency (USEPA). Given the large number of chemicals that are carcinogens or reproductive/developmental toxicants, regulatory concerns should focus on those that have high potential for human exposure, e.g., widely distributed or easily absorbed solvents, metals, environmental mixtures, or reactive agents. In this paper, we present a list of 33 potential priority carcinogens and reproductive/developmental toxicants, including alcoholic beverages, asbestos, benzene, chlorinated solvents, formaldehyde, glycol ethers, lead, tobacco smoke, and toluene.","Regulation of priority carcinogens and reproductive or developmental toxicants Abs: In California, 370 carcinogens and 112 reproductive/developmental toxicants have been identified as a result of the State's Safe Drinking Water and Toxic Enforcement Act of 1986. They include pesticides, solvents, metals, industrial intermediates, environmental mixtures, and reactive agents. Occupational, environmental, and consumer product exposures that involve these agents are regulated under the Act. At levels of concern, businesses must provide warnings for and limit discharges of those chemicals. The lists of chemicals were compiled following systematic review of published data, including technical reports from the U.S. Public Health Service--National Toxicology Program (NTP), and evaluation of recommendations from authoritative bodies such as the International Agency for Research on Cancer (IARC) and the U.S. Environmental Protection Agency (USEPA). Given the large number of chemicals that are carcinogens or reproductive/developmental toxicants, regulatory concerns should focus on those that have high potential for human exposure, e.g., widely distributed or easily absorbed solvents, metals, environmental mixtures, or reactive agents. In this paper, we present a list of 33 potential priority carcinogens and reproductive/developmental toxicants, including alcoholic beverages, asbestos, benzene, chlorinated solvents, formaldehyde, glycol ethers, lead, tobacco smoke, and toluene."
660306,Morgan 1997,The Biological Exposure Indices: A key component in protecting workers from toxic chemicals,"BIOSIS COPYRIGHT: BIOL ABS. Biological monitoring of exposure to chemicals in the workplace is an important component of exposure assessment and prevention of adverse health effects. It should be employed in conjunction with ambient air monitoring to provide information on the absorbed dose of a chemical agent and the effect of all routes of exposure. Judgments regarding the acceptable level of a chemical or its metabolite in biological samples are facilitated by comparison to a reference value. The American Conference of Governmental Industrial Hygienists has established a series of recommended reference values called the Biological Exposure Indices (BEI). The history and characteristics of the BEI are reviewed, and their suitability for use by occupational health specialists is examined. A number of challenges and stimuli to the continued development and improvement of these reference values are described, and the impact of recent advances in macromolecular biology is assessed.","The Biological Exposure Indices: A key component in protecting workers from toxic chemicals Abs: BIOSIS COPYRIGHT: BIOL ABS. Biological monitoring of exposure to chemicals in the workplace is an important component of exposure assessment and prevention of adverse health effects. It should be employed in conjunction with ambient air monitoring to provide information on the absorbed dose of a chemical agent and the effect of all routes of exposure. Judgments regarding the acceptable level of a chemical or its metabolite in biological samples are facilitated by comparison to a reference value. The American Conference of Governmental Industrial Hygienists has established a series of recommended reference values called the Biological Exposure Indices (BEI). The history and characteristics of the BEI are reviewed, and their suitability for use by occupational health specialists is examined. A number of challenges and stimuli to the continued development and improvement of these reference values are described, and the impact of recent advances in macromolecular biology is assessed."
659885,Churn 1993,Industrial Wastes Chemical and Allied Products,BIOSIS COPYRIGHT: BIOL ABS. RRM REVIEW WASTEWATER TREATMENT WASTE MANAGEMENT SOIL POLLUTION CONTROL GROUNDWATER POLLUTION CONTROL CLEAN WATER ACT LEGISLATION REGULATION CHEMISTRY ANALYTICAL METHODS GOVERNMENT POLICY VOC DEVELOPING COUNTRIES,Industrial Wastes Chemical and Allied Products Abs: BIOSIS COPYRIGHT: BIOL ABS. RRM REVIEW WASTEWATER TREATMENT WASTE MANAGEMENT SOIL POLLUTION CONTROL GROUNDWATER POLLUTION CONTROL CLEAN WATER ACT LEGISLATION REGULATION CHEMISTRY ANALYTICAL METHODS GOVERNMENT POLICY VOC DEVELOPING COUNTRIES
659767,Assmuth 1996,"Comparative risk analysis of waste site toxicants by indices based on concentration distributions, fluxes, environmental fate and critical effects","The environmental risks associated with toxicants in leachate emissions from 43 Finnish waste sites were analysed and prioritized by site-aggregating procedures using various linear models and indices based on statistics of observed concentration distributions, on available data concerning volatilization and decay, on flux estimates and on toxic values to humans and to aquatic organisms. Considering only concentrations (90% fractiles of distributions) and effect criteria, 1,2-dichloroethane, 2,4,6-trichlorophenol and trichloroethene were the most important toxicants in terms of drinking water standard violation, while PCBs and Cr along with 1,2-dichloroethane displayed the values of carcinogenic risk index, and Cu, PCBs, toluene and endrin ranked highest in terms of aquatic ecotoxicity. The distributions of ecotoxicity indices reached rather consistently more alarming levels than those of health risk indices. When sinks were accounted for, the persistent and nonvolatile","Comparative risk analysis of waste site toxicants by indices based on concentration distributions, fluxes, environmental fate and critical effects Abs: The environmental risks associated with toxicants in leachate emissions from 43 Finnish waste sites were analysed and prioritized by site-aggregating procedures using various linear models and indices based on statistics of observed concentration distributions, on available data concerning volatilization and decay, on flux estimates and on toxic values to humans and to aquatic organisms. Considering only concentrations (90% fractiles of distributions) and effect criteria, 1,2-dichloroethane, 2,4,6-trichlorophenol and trichloroethene were the most important toxicants in terms of drinking water standard violation, while PCBs and Cr along with 1,2-dichloroethane displayed the values of carcinogenic risk index, and Cu, PCBs, toluene and endrin ranked highest in terms of aquatic ecotoxicity. The distributions of ecotoxicity indices reached rather consistently more alarming levels than those of health risk indices. When sinks were accounted for, the persistent and nonvolatile"
659416,Reed et al. 1998,Physicochemical Processes,BIOSIS COPYRIGHT: BIOL ABS. RRM LITERATURE REVIEW PARTICLE SIZE DISTRIBUTION PARTICLE REMOVAL PRECIPITATION COAGULATION FLOCCULATION SEDIMENTATION FLOTATION INORGANIC CHEMICALS SORPTION ORGANIC CHEMICALS MEMBRANE PROCESSES OXIDATION REDUCTION AIR STRIPPING METHODOLOGY SANITATION POLLUTION CONTROL WATER TREATMENT WATER TREATMENT METHOD,Physicochemical Processes Abs: BIOSIS COPYRIGHT: BIOL ABS. RRM LITERATURE REVIEW PARTICLE SIZE DISTRIBUTION PARTICLE REMOVAL PRECIPITATION COAGULATION FLOCCULATION SEDIMENTATION FLOTATION INORGANIC CHEMICALS SORPTION ORGANIC CHEMICALS MEMBRANE PROCESSES OXIDATION REDUCTION AIR STRIPPING METHODOLOGY SANITATION POLLUTION CONTROL WATER TREATMENT WATER TREATMENT METHOD
659412,Pollis et al. 1998,Effects of Chemicals on Microorganisms,"Staples et al. (1997) reviewed and summarized the database of acute and chronic aquatic toxicity data for 18 phthalate esters for freshwater and saltwater aquatic microorganisms and algae as well as freshwater and saltwater invertebrates and fish. Phthalate esters are commonly used in polyvinyl chloride (PVC) and are found in plastic tubing, floor tiles, automobile upholstery, etc. The results of most studies indicate that acute and chronic toxicity to microorganisms, algae, aquatic invertebrates, and fish are limited to the lower molecular weight phthalate esters (i.e., dimethylphthalate, diethylphthalate, diallylphthalate, dipropylphthalate, dibutylphthalate, diisobutylphthalate, and butylbenzylphthalate). In contrast, higher molecular weight phthalate esters are not acutely or chronically toxic to aquatic organisms. Altogether, nearly 400 test results covering more than 60 species of microorganisms, algae, invertebrates, and fish are reported for both freshwater and saltwater aquatic species.","Effects of Chemicals on Microorganisms Abs: Staples et al. (1997) reviewed and summarized the database of acute and chronic aquatic toxicity data for 18 phthalate esters for freshwater and saltwater aquatic microorganisms and algae as well as freshwater and saltwater invertebrates and fish. Phthalate esters are commonly used in polyvinyl chloride (PVC) and are found in plastic tubing, floor tiles, automobile upholstery, etc. The results of most studies indicate that acute and chronic toxicity to microorganisms, algae, aquatic invertebrates, and fish are limited to the lower molecular weight phthalate esters (i.e., dimethylphthalate, diethylphthalate, diallylphthalate, dipropylphthalate, dibutylphthalate, diisobutylphthalate, and butylbenzylphthalate). In contrast, higher molecular weight phthalate esters are not acutely or chronically toxic to aquatic organisms. Altogether, nearly 400 test results covering more than 60 species of microorganisms, algae, invertebrates, and fish are reported for both freshwater and saltwater aquatic species."
658823,Jop et al. 1992,Application of the Short-Term Chronic Test with Ceriodaphnia-Dubia in Identifying Sources of Toxicity in Industrial Wastewaters,Biosis copyright: biol abs. rrm invertebrate wastewater treatment water pollution control risk assessment regulation epa usa,Application of the Short-Term Chronic Test with Ceriodaphnia-Dubia in Identifying Sources of Toxicity in Industrial Wastewaters Abs: Biosis copyright: biol abs. rrm invertebrate wastewater treatment water pollution control risk assessment regulation epa usa
658534,Cozzani et al. 1998,Formation of hazardous compounds by unwanted reactions in industrial accidents,"'Unwanted reactions' caused by the accidental contact of reactive substances may result in either physical effects, such as fire or explosions, or chemical effects, as the formation and release of hazardous reaction products. To help to develop criteria for identifying such reactions, a number of industrial accidents caused by 'unwanted reactions' were analyzed. The chemical systems more frequently involved in these accidents and the substances released were identified. The process operations during which the accidents took place and the immediate causes of the accidents were also examined. Simple criteria for the identification of hazard conditions with respect to 'unwanted reaction' accidents were derived from European Council Directive 67/548 for the classification, packaging and labelling of dangerous substances. The validity of these criteria was verified using the data on accidental events.","Formation of hazardous compounds by unwanted reactions in industrial accidents Abs: 'Unwanted reactions' caused by the accidental contact of reactive substances may result in either physical effects, such as fire or explosions, or chemical effects, as the formation and release of hazardous reaction products. To help to develop criteria for identifying such reactions, a number of industrial accidents caused by 'unwanted reactions' were analyzed. The chemical systems more frequently involved in these accidents and the substances released were identified. The process operations during which the accidents took place and the immediate causes of the accidents were also examined. Simple criteria for the identification of hazard conditions with respect to 'unwanted reaction' accidents were derived from European Council Directive 67/548 for the classification, packaging and labelling of dangerous substances. The validity of these criteria was verified using the data on accidental events."
658249,Mark and  Solbe 1998,Analysis of the ECETOC aquatic toxicity (EAT) database. V - The relevance of Daphnia magna as a representative test species,"The ECETOC Aquatic Toxicity database was used to investigate the response of the Cladoceran Daphnia magna Straus in various types of toxicity test and to compare its sensitivity with that of other invertebrates and fish. Repeatability of 48-h EC50 data was good, the range being no more than a factor of 3 for eight of the eleven chemicals where multiple results were available. In 21-day tests, for both EC50 and NOEC, reproduction was a more sensitive endpoint than growth or lethality, but not markedly so. There was no general rule that D. magna was more, or less, sensitive than other invertebrates, including D. pulex. Lindane and Endosulphan were more toxic to fish than to Daphnia but the reverse was the case for Parathion, copper, a cationic surfactant and to a lesser extent cadmium. For another eight substances 48-hour tests with Daphnia would have predicted the 96-h EC50 to freshwater fish within a factor of 5 or less. The same was true for long-term studies with Daphnia and fish: there was no consistent difference in sensitivity (except that Daphnia was always more sensitive to metals) and the crustacean could be used to predict long-term toxicity to fish within a factor of 2 for half the non-metals and a factor of 5 for three-quarters of non-metals.","Analysis of the ECETOC aquatic toxicity (EAT) database. V - The relevance of Daphnia magna as a representative test species Abs: The ECETOC Aquatic Toxicity database was used to investigate the response of the Cladoceran Daphnia magna Straus in various types of toxicity test and to compare its sensitivity with that of other invertebrates and fish. Repeatability of 48-h EC50 data was good, the range being no more than a factor of 3 for eight of the eleven chemicals where multiple results were available. In 21-day tests, for both EC50 and NOEC, reproduction was a more sensitive endpoint than growth or lethality, but not markedly so. There was no general rule that D. magna was more, or less, sensitive than other invertebrates, including D. pulex. Lindane and Endosulphan were more toxic to fish than to Daphnia but the reverse was the case for Parathion, copper, a cationic surfactant and to a lesser extent cadmium. For another eight substances 48-hour tests with Daphnia would have predicted the 96-h EC50 to freshwater fish within a factor of 5 or less. The same was true for long-term studies with Daphnia and fish: there was no consistent difference in sensitivity (except that Daphnia was always more sensitive to metals) and the crustacean could be used to predict long-term toxicity to fish within a factor of 2 for half the non-metals and a factor of 5 for three-quarters of non-metals."
658035,Peters 1999,Chelant extraction of heavy metals from contaminated soils,"BIOSIS COPYRIGHT: BIOL ABS. The current state of the art regarding the use of chelating agents to extract heavy metal contaminants has been addressed. Results are presented for treatability studies conducted as worst-case and representative soils from Aberdeen Proving Ground's J-Field for extraction of copper (Cu), lead (Pb), and zinc (Zn). The particle size distribution characteristics of the soils determined from hydrometer tests are approximately 60% sand, 30% silt, and 10% clay. Sequential extractions were performed on reducible oxides). The metals Cu, Pb, Zn, and Cr have greater than 70% of their distribution informs amenable to soil washing techniques, while Cd, Mn, and Fe are somewhat less amenable to soil washing using chelant extraction. However, the concentrations of Cd and Mn are low in the contaminated soil. From the batch chelant extraction studies, ethylenediaminetetraacetic acid (EDTA), citric acid, and nitrilotriacetic acid (NTA) were all effective in removing copper, lead, and zin","Chelant extraction of heavy metals from contaminated soils Abs: BIOSIS COPYRIGHT: BIOL ABS. The current state of the art regarding the use of chelating agents to extract heavy metal contaminants has been addressed. Results are presented for treatability studies conducted as worst-case and representative soils from Aberdeen Proving Ground's J-Field for extraction of copper (Cu), lead (Pb), and zinc (Zn). The particle size distribution characteristics of the soils determined from hydrometer tests are approximately 60% sand, 30% silt, and 10% clay. Sequential extractions were performed on reducible oxides). The metals Cu, Pb, Zn, and Cr have greater than 70% of their distribution informs amenable to soil washing techniques, while Cd, Mn, and Fe are somewhat less amenable to soil washing using chelant extraction. However, the concentrations of Cd and Mn are low in the contaminated soil. From the batch chelant extraction studies, ethylenediaminetetraacetic acid (EDTA), citric acid, and nitrilotriacetic acid (NTA) were all effective in removing copper, lead, and zin"
657960,Di Toro et al. 1991,Technical Basis for Establishing Sediment Quality Criteria for Nonionic Organic Chemicals Using Equilibrium Partitioning,Biosis copyright: biol abs. rrm review organism toxicity ecosystem contamination environmental analysis method,Technical Basis for Establishing Sediment Quality Criteria for Nonionic Organic Chemicals Using Equilibrium Partitioning Abs: Biosis copyright: biol abs. rrm review organism toxicity ecosystem contamination environmental analysis method
657893,Roff et al. 2004,Dermal exposure to electroplating fluids and metalworking fluids in the UK,"This paper describes workplace dermal exposure measurements that were carried out by the Health and Safety Laboratory as part of the EU RISKOFDERM project. Exposure to metalworking fluids (MWFs) was measured at three sites on 25 subjects who were 'mechanically treating solid objects' as they loaded and supervised milling and boring machines and lathes. Thirty-one samples were obtained, of which 18 were exposures to neat mineral oils and 13 to water-oil mixes. All subjects wore Tyvek whole-body oversuits that were analysed in their entirety to extract the MWF. The geometric mean surface loading rate of the 31 oversuits was 62 micro g/cm(2)/h (GSD = 4.6) and of the seven pairs of sampling gloves (worn inside protective gloves) was 2900 micro g/cm(2)/h (GSD = 1.67). Exposure to electroplating fluids was measured at three sites on 27 subjects who were dipping objects into tanks of either chromic acid, nickel sulphate, copper sulphate, copper cyanide or zinc hydroxide. All subjects wore Tyvek whole-body oversuits that were surface scanned over their areas using a portable X-ray fluorescence spectrometer to detect all the metal atoms simultaneously. Contamination was assessed using the method of Dirichlet tessellation. The geometric mean surface loading rate of the 26 oversuits was 37 micro g/cm(2)/h (GSD = 3.5) and of the 25 pairs of sampling gloves (worn inside protective gloves) was 190 micro g/cm(2)/h (GSD = 2.75). Almost all of the electroplating samples were below the limit of quantification. More than one species of metal atoms was found on some of the samples afterwards, indicating cross-contamination from other baths during the sampling period","Dermal exposure to electroplating fluids and metalworking fluids in the UK Abs: This paper describes workplace dermal exposure measurements that were carried out by the Health and Safety Laboratory as part of the EU RISKOFDERM project. Exposure to metalworking fluids (MWFs) was measured at three sites on 25 subjects who were 'mechanically treating solid objects' as they loaded and supervised milling and boring machines and lathes. Thirty-one samples were obtained, of which 18 were exposures to neat mineral oils and 13 to water-oil mixes. All subjects wore Tyvek whole-body oversuits that were analysed in their entirety to extract the MWF. The geometric mean surface loading rate of the 31 oversuits was 62 micro g/cm(2)/h (GSD = 4.6) and of the seven pairs of sampling gloves (worn inside protective gloves) was 2900 micro g/cm(2)/h (GSD = 1.67). Exposure to electroplating fluids was measured at three sites on 27 subjects who were dipping objects into tanks of either chromic acid, nickel sulphate, copper sulphate, copper cyanide or zinc hydroxide. All subjects wore Tyvek whole-body oversuits that were surface scanned over their areas using a portable X-ray fluorescence spectrometer to detect all the metal atoms simultaneously. Contamination was assessed using the method of Dirichlet tessellation. The geometric mean surface loading rate of the 26 oversuits was 37 micro g/cm(2)/h (GSD = 3.5) and of the 25 pairs of sampling gloves (worn inside protective gloves) was 190 micro g/cm(2)/h (GSD = 2.75). Almost all of the electroplating samples were below the limit of quantification. More than one species of metal atoms was found on some of the samples afterwards, indicating cross-contamination from other baths during the sampling period"
656795,Harrison et al. 2004,What is responsible for the carcinogenicity of PM2.5?,"Aims: To test whether exposure to known chemical carcinogens in the atmosphere is capable of explaining the association between concentrations of PM2.5 and lung cancer mortality observed in the extended ACS Cohort Study.(1) Methods: Taking account of possible cancer latency periods, lung cancer rates due to exposure to As, Cr(VI), Ni, and polycyclic aromatic hydrocarbons (PAHs) were calculated based on a review of historic measurements from the United States and the use of unit risk factors. The predicted rates were compared with rates of cancer attributable to PM2.5 derived from data in the ACS study.(1) Results: Despite many uncertainties, the lung cancer rates predicted due to exposure to US urban concentrations of the carcinogenic substances arsenic, nickel, chromium, and PAHs measured in 1960 and earlier ( and hence allowing for a latency period) were within the range predicted on the basis of the ACS Cohort Study due to exposure of PM2.5. There are, however, many caveats, most particularly that for the chemical carcinogens to be responsible for the effects attributed to PM2.5 by Pope and colleagues,(1) the concentrations of chemical carcinogens at the time of relevant exposures would need to be correlated with the concentrations of PM2.5 in US urban areas measured between 1979 and 2000 and used in the ACS study. Conclusions: While many uncertainties remain, it appears plausible that known chemical carcinogens are responsible for the lung cancers attributed to PM2.5 exposure in the extended ACS Cohort Study. However, the possibility should not be ruled out that particulate matter is capable of causing lung cancer independent of the presence of known carcinogens.","What is responsible for the carcinogenicity of PM2.5? Abs: Aims: To test whether exposure to known chemical carcinogens in the atmosphere is capable of explaining the association between concentrations of PM2.5 and lung cancer mortality observed in the extended ACS Cohort Study.(1) Methods: Taking account of possible cancer latency periods, lung cancer rates due to exposure to As, Cr(VI), Ni, and polycyclic aromatic hydrocarbons (PAHs) were calculated based on a review of historic measurements from the United States and the use of unit risk factors. The predicted rates were compared with rates of cancer attributable to PM2.5 derived from data in the ACS study.(1) Results: Despite many uncertainties, the lung cancer rates predicted due to exposure to US urban concentrations of the carcinogenic substances arsenic, nickel, chromium, and PAHs measured in 1960 and earlier ( and hence allowing for a latency period) were within the range predicted on the basis of the ACS Cohort Study due to exposure of PM2.5. There are, however, many caveats, most particularly that for the chemical carcinogens to be responsible for the effects attributed to PM2.5 by Pope and colleagues,(1) the concentrations of chemical carcinogens at the time of relevant exposures would need to be correlated with the concentrations of PM2.5 in US urban areas measured between 1979 and 2000 and used in the ACS study. Conclusions: While many uncertainties remain, it appears plausible that known chemical carcinogens are responsible for the lung cancers attributed to PM2.5 exposure in the extended ACS Cohort Study. However, the possibility should not be ruled out that particulate matter is capable of causing lung cancer independent of the presence of known carcinogens."
656254,Cohen et al. 2010,Effects of metal compounds with distinct physicochemical properties on iron homeostasis and antibacterial activity in the lungs: Chromium and vanadium,"In situ reactions of metal ions or their compounds are important mechanisms by which particles alter lung immune responses. The authors hypothesized that major determinants of the immunomodulatory effect of any metal include its redox behavior/properties, oxidation state, and/or solubility, and that the toxicities arising from differences in physicochemical parameters are manifest, in part, via differential shifts in lung iron (Fe) homeostasis. To test the hypotheses, immunomodulatory potentials for both pentavalent vanadium (VV; as soluble metavanadate or insoluble vanadium pentoxide) and hexavalent chromium (CrVI; as soluble sodium chromate or insoluble calcium chromate) were quantified in rats after inhalation (5h/day for 5 days) of each at 100 microg metal/m3. Differences in effects on local bacterial resistance between the two VV, and between each CrVI, agents suggested that solubility might be a determinant of in situ immunotoxicity. For the soluble forms, VV had a greater impact on resistance than CrVI, indicating that redox behavior/properties was likely also a determinant. The soluble VV agent was the strongest immunomodulant. Regarding Fe homeostasis, both VV agents had dramatic effects on airway Fe levels. Both also impacted local immune/airway epithelial cell Fe levels in that there were significant increases in production of select cytokines/chemokines whose genes are subject to regulation by HIF-1 (whose intracellular longevity is related to cell Fe status). Our findings contribute to a better understanding of the role that metal compound properties play in respiratory disease pathogenesis and provide a rationale for differing pulmonary immunotoxicities of commonly encountered ambient metal pollutants.","Effects of metal compounds with distinct physicochemical properties on iron homeostasis and antibacterial activity in the lungs: Chromium and vanadium Abs: In situ reactions of metal ions or their compounds are important mechanisms by which particles alter lung immune responses. The authors hypothesized that major determinants of the immunomodulatory effect of any metal include its redox behavior/properties, oxidation state, and/or solubility, and that the toxicities arising from differences in physicochemical parameters are manifest, in part, via differential shifts in lung iron (Fe) homeostasis. To test the hypotheses, immunomodulatory potentials for both pentavalent vanadium (VV; as soluble metavanadate or insoluble vanadium pentoxide) and hexavalent chromium (CrVI; as soluble sodium chromate or insoluble calcium chromate) were quantified in rats after inhalation (5h/day for 5 days) of each at 100 microg metal/m3. Differences in effects on local bacterial resistance between the two VV, and between each CrVI, agents suggested that solubility might be a determinant of in situ immunotoxicity. For the soluble forms, VV had a greater impact on resistance than CrVI, indicating that redox behavior/properties was likely also a determinant. The soluble VV agent was the strongest immunomodulant. Regarding Fe homeostasis, both VV agents had dramatic effects on airway Fe levels. Both also impacted local immune/airway epithelial cell Fe levels in that there were significant increases in production of select cytokines/chemokines whose genes are subject to regulation by HIF-1 (whose intracellular longevity is related to cell Fe status). Our findings contribute to a better understanding of the role that metal compound properties play in respiratory disease pathogenesis and provide a rationale for differing pulmonary immunotoxicities of commonly encountered ambient metal pollutants."
654686,Aitken et al. 1994,Treatment Systems Activated Sludge and Other Aerobic Suspended Culture Processes,BIOSIS COPYRIGHT: BIOL ABS. RRM LITERATURE REVIEW COLIFORMS PROTOZOA WATER QUALITY BIORETENTION HERBICIDE PESTICIDE STORMWATER POLLUTION MUNICIPAL WASTE WATER TREATMENT DRINKING WATER MATHEMATICAL MODEL TOXICITY SEDIMENTATION FLOTATION,Treatment Systems Activated Sludge and Other Aerobic Suspended Culture Processes Abs: BIOSIS COPYRIGHT: BIOL ABS. RRM LITERATURE REVIEW COLIFORMS PROTOZOA WATER QUALITY BIORETENTION HERBICIDE PESTICIDE STORMWATER POLLUTION MUNICIPAL WASTE WATER TREATMENT DRINKING WATER MATHEMATICAL MODEL TOXICITY SEDIMENTATION FLOTATION
651998,Alvarez et al. 2007,The adsorption of chromium (VI) from industrial wastewater by acid and base-activated lignocellulosic residues,"This study deals with the adsorption of Cr(VI) from synthetic and industrial wastewater, produced by a sewage plant. The activated carbons were prepared from a lignocellulosic raw material by thermal treatment at 450 and 650 degrees C in the presence of acid (AlCl(3), HCl, H(3)PO(4) and H(2)SO(4)) and base (NaOH) agents. To optimize the adsorption of Cr(VI), the chemical modifications caused by each activating agent (related to the capability of Cr(VI) removal), and the optimal experimental conditions of the pH, Cr(VI) concentration, adsorbent dose and residence time, were studied. Thus, treatment with H(3)PO(4) gives rise to carbons with a high surface area and high efficiency for Cr(VI) removal at short equilibrium times. In contrast, the generation of active surface sites by means of NaOH requires longer equilibrium times, the adsorption being less effective than in the former case. The adsorption isotherms obey the Langmuir equation only in the first stages of the reaction but fit the Freundlich equations over the whole range studied, so the heat of adsorption can be easily calculated. The results also show that the activated carbons obtained can be recovered by filtration with an efficiency of 30% in the third cycle.","The adsorption of chromium (VI) from industrial wastewater by acid and base-activated lignocellulosic residues Abs: This study deals with the adsorption of Cr(VI) from synthetic and industrial wastewater, produced by a sewage plant. The activated carbons were prepared from a lignocellulosic raw material by thermal treatment at 450 and 650 degrees C in the presence of acid (AlCl(3), HCl, H(3)PO(4) and H(2)SO(4)) and base (NaOH) agents. To optimize the adsorption of Cr(VI), the chemical modifications caused by each activating agent (related to the capability of Cr(VI) removal), and the optimal experimental conditions of the pH, Cr(VI) concentration, adsorbent dose and residence time, were studied. Thus, treatment with H(3)PO(4) gives rise to carbons with a high surface area and high efficiency for Cr(VI) removal at short equilibrium times. In contrast, the generation of active surface sites by means of NaOH requires longer equilibrium times, the adsorption being less effective than in the former case. The adsorption isotherms obey the Langmuir equation only in the first stages of the reaction but fit the Freundlich equations over the whole range studied, so the heat of adsorption can be easily calculated. The results also show that the activated carbons obtained can be recovered by filtration with an efficiency of 30% in the third cycle."
651772,Rusznak et al. 1999,Cigarette smoke potentiates house dust mite allergen-induced increase in the permeability of human bronchial epithelial cells in vitro,"Although studies have suggested that exposure to cigarette smoke (CS) may be associated with the development of atopy, the mechanisms underlying this are not clearly understood. It has been suggested that CS impairs the barrier function of the airway epithelium, leading to increased access of allergens such as those of the house dust mite (HDM) Dermatophagoides pteronyssinus (Der p) to antigen-presenting cells, with subsequent allergic sensitization. In order to test this hypothesis, we established primary explant cultures of human bronchial epithelial cells (HBEC) in cell culture inserts, and exposed these for 20 min, 1 h, 3 h, and 6 h to CS or air in the absence or presence of 300 ng/ml Der p, and then further incubated the cultures over a period of 24 h. The HBEC cultures were assessed for changes in permeability as measured by changes in: (1) electrical resistance (ER); and (2) passage of 14C-labeled bovine serum albumin (14C-BSA) and Der p allergens across the HBEC cultures. We also assessed the effects of protease inhibitors and the antioxidant glutathione (GSH) in this experimental system. Damage to HBEC cultures was assessed by the release of [51Cr]sodium chromate from prelabeled cells, and by release of lactate dehydrogenase (LDH). Twenty minutes of exposure to CS as compared with exposure to air did not significantly alter either the ER or passage of 14C-BSA across the HBEC cultures. In contrast, incubation with Der p led to a significant increase in the permeability of HBEC cultures, an effect that was enhanced by exposure to CS but was abrogated by the specific protease inhibitors and GSH. Passage of Der p was also increased by exposure to CS. Exposure of HBEC cultures to CS led to a significant release of 51Cr and LDH from these cells as compared with cells exposed to air. This effect was augmented further when HBEC cultures were incubated with Der p. Exposure of HBEC cultures for 1 h, 3 h, and 6 h to CS led to a markedly significant dose- and time-dependent increase in the permeability of these cells. These results suggest that exposure to CS significantly enhances Der p-induced decreases in electrical resistance and the increased passage across HBEC cultures of 14C-BSA and of the Der p allergen itself.","Cigarette smoke potentiates house dust mite allergen-induced increase in the permeability of human bronchial epithelial cells in vitro Abs: Although studies have suggested that exposure to cigarette smoke (CS) may be associated with the development of atopy, the mechanisms underlying this are not clearly understood. It has been suggested that CS impairs the barrier function of the airway epithelium, leading to increased access of allergens such as those of the house dust mite (HDM) Dermatophagoides pteronyssinus (Der p) to antigen-presenting cells, with subsequent allergic sensitization. In order to test this hypothesis, we established primary explant cultures of human bronchial epithelial cells (HBEC) in cell culture inserts, and exposed these for 20 min, 1 h, 3 h, and 6 h to CS or air in the absence or presence of 300 ng/ml Der p, and then further incubated the cultures over a period of 24 h. The HBEC cultures were assessed for changes in permeability as measured by changes in: (1) electrical resistance (ER); and (2) passage of 14C-labeled bovine serum albumin (14C-BSA) and Der p allergens across the HBEC cultures. We also assessed the effects of protease inhibitors and the antioxidant glutathione (GSH) in this experimental system. Damage to HBEC cultures was assessed by the release of [51Cr]sodium chromate from prelabeled cells, and by release of lactate dehydrogenase (LDH). Twenty minutes of exposure to CS as compared with exposure to air did not significantly alter either the ER or passage of 14C-BSA across the HBEC cultures. In contrast, incubation with Der p led to a significant increase in the permeability of HBEC cultures, an effect that was enhanced by exposure to CS but was abrogated by the specific protease inhibitors and GSH. Passage of Der p was also increased by exposure to CS. Exposure of HBEC cultures to CS led to a significant release of 51Cr and LDH from these cells as compared with cells exposed to air. This effect was augmented further when HBEC cultures were incubated with Der p. Exposure of HBEC cultures for 1 h, 3 h, and 6 h to CS led to a markedly significant dose- and time-dependent increase in the permeability of these cells. These results suggest that exposure to CS significantly enhances Der p-induced decreases in electrical resistance and the increased passage across HBEC cultures of 14C-BSA and of the Der p allergen itself."
651714,Gong et al. 1997,Determination of tributyltin in toluene extract from sea water by graphite furnace atomic absorption spectrometry with a new matrix modifier,"A new matrix modifier composed of calcium and chromium[VI] was proposed for the determination of tributyltin (TBT) in toluene extract from sea water containing sediment by graphite furnace atomic absorption spectrometry (GFAAS). Fourteen inorganic and organic compounds (barium, calcium, chromium[VI], lanthanum, magnesium, nickel, palladium, strontium, calcium-chromium[VI], calcium-strontium, nickel isocaprylate, 5%-, 10%-aqueous solution of ascorbic acid and toluene-saturated solution of ascorbic acid) as a matrix modifier were comparatively studied and a matrix modifier composed from 5 microg of calcium and 1 microg of chromium[VI] was found to give the best performance. The interference effects of co-existing elements in sea water containing sediment (aluminium, iron, magnesium, sodium and strontium) were studied. TBT in eight toluene extracts was determined by GFAAS with the proposed matrix modifier. The relative standard deviation was 3.0% for 63 ng ml(-1) of TBT (n = 11). The recoveries were 88-104%. The characteristic mass was 7 pg. The linearity range was 0-250 ng mg(-1).","Determination of tributyltin in toluene extract from sea water by graphite furnace atomic absorption spectrometry with a new matrix modifier Abs: A new matrix modifier composed of calcium and chromium[VI] was proposed for the determination of tributyltin (TBT) in toluene extract from sea water containing sediment by graphite furnace atomic absorption spectrometry (GFAAS). Fourteen inorganic and organic compounds (barium, calcium, chromium[VI], lanthanum, magnesium, nickel, palladium, strontium, calcium-chromium[VI], calcium-strontium, nickel isocaprylate, 5%-, 10%-aqueous solution of ascorbic acid and toluene-saturated solution of ascorbic acid) as a matrix modifier were comparatively studied and a matrix modifier composed from 5 microg of calcium and 1 microg of chromium[VI] was found to give the best performance. The interference effects of co-existing elements in sea water containing sediment (aluminium, iron, magnesium, sodium and strontium) were studied. TBT in eight toluene extracts was determined by GFAAS with the proposed matrix modifier. The relative standard deviation was 3.0% for 63 ng ml(-1) of TBT (n = 11). The recoveries were 88-104%. The characteristic mass was 7 pg. The linearity range was 0-250 ng mg(-1)."
651692,Bernstein and  Vaughan 1999,Cultured keratinocytes in in vitro dermatotoxicological investigation: a review,"The keratinocyte is responsible for the architecture of the epidermis, that portion of the skin that forms the environmental barrier necessary for survival. It also interacts with other cell types in the epidermis in response to various environmental influences. This cell type is used frequently for in vitro cutaneous toxicological investigations as an alternative to whole-animal studies. Several areas of cutaneous research using cultured keratinocytes are germane as regards the scope of this journal. The following areas of biomedical research were reviewed: (1) dermatotoxicology, including environmental chemicals, antiseptics, drugs, metals, and pesticides; (2) immunotoxicology, including inflammation and allergic dermatitis; (3) radiation, including ultraviolet and x-irradiation; and (4) the development of assays as alternatives to whole-animal testing. Due to the abundance of such investigations reported in the last 30 years, this review is limited mainly to reviewing reports published in this decade.","Cultured keratinocytes in in vitro dermatotoxicological investigation: a review Abs: The keratinocyte is responsible for the architecture of the epidermis, that portion of the skin that forms the environmental barrier necessary for survival. It also interacts with other cell types in the epidermis in response to various environmental influences. This cell type is used frequently for in vitro cutaneous toxicological investigations as an alternative to whole-animal studies. Several areas of cutaneous research using cultured keratinocytes are germane as regards the scope of this journal. The following areas of biomedical research were reviewed: (1) dermatotoxicology, including environmental chemicals, antiseptics, drugs, metals, and pesticides; (2) immunotoxicology, including inflammation and allergic dermatitis; (3) radiation, including ultraviolet and x-irradiation; and (4) the development of assays as alternatives to whole-animal testing. Due to the abundance of such investigations reported in the last 30 years, this review is limited mainly to reviewing reports published in this decade."
648150,Wise et al. 2003,Barium chromate is cytotoxic and genotoxic to human lung cells,"Hexavalent chromium (Cr(VI)) compounds are widely accepted as human lung carcinogens. However, there have been few investigations of the genotoxicity of Cr(VI) in human lung cells. Moreover, our knowledge of the effects of Cr(VI) in human lung cells is further limited because the available data generally focus on the effects of only lead chromate (PbCrO(4)) and sodium chromate (Na(2)CrO(4)). To fully understand these carcinogenic compounds, the genotoxic effects to its target cells need to be evaluated for additional Cr(VI) salts. Accordingly, we investigated the cytotoxicity and clastogenicity of barium chromate (BC) in a human lung cell culture model (WTHBF-6 cells). We found that BC induced concentration-dependent cytotoxicity in WTHBF-6 cells, with relative survival of 88%, 74%, 67%, 12%, 3%, and 0.1% after exposure to 0.01, 0.05, 0.1, 0.5, 1, and 5 microg/cm(2) BC, respectively. Similarly, the amount of chromosomal damage also increased with concentration after a 24-h exposure. Specifically, 0.01, 0.05, 0.1, and 0.5 microg/cm(2) BaCrO(4) damaged 5%, 9%, 22%, and 49% of metaphase cells, with the total damage reaching 5, 10, 28, and 65 aberrations per 100 metaphases, respectively. Concentrations of 1 and 5 microg/cm(2) BC induced a profound cell cycle delay, and no metaphases were observed. The spectrum of damage included chromatid and chromosome-type lesions consistent with mechanistic events associated with the activation of oncogenes and inactivation of tumor suppressor genes. Overall the data indicate that BC is cytotoxic and genotoxic to human lung cells.","Barium chromate is cytotoxic and genotoxic to human lung cells Abs: Hexavalent chromium (Cr(VI)) compounds are widely accepted as human lung carcinogens. However, there have been few investigations of the genotoxicity of Cr(VI) in human lung cells. Moreover, our knowledge of the effects of Cr(VI) in human lung cells is further limited because the available data generally focus on the effects of only lead chromate (PbCrO(4)) and sodium chromate (Na(2)CrO(4)). To fully understand these carcinogenic compounds, the genotoxic effects to its target cells need to be evaluated for additional Cr(VI) salts. Accordingly, we investigated the cytotoxicity and clastogenicity of barium chromate (BC) in a human lung cell culture model (WTHBF-6 cells). We found that BC induced concentration-dependent cytotoxicity in WTHBF-6 cells, with relative survival of 88%, 74%, 67%, 12%, 3%, and 0.1% after exposure to 0.01, 0.05, 0.1, 0.5, 1, and 5 microg/cm(2) BC, respectively. Similarly, the amount of chromosomal damage also increased with concentration after a 24-h exposure. Specifically, 0.01, 0.05, 0.1, and 0.5 microg/cm(2) BaCrO(4) damaged 5%, 9%, 22%, and 49% of metaphase cells, with the total damage reaching 5, 10, 28, and 65 aberrations per 100 metaphases, respectively. Concentrations of 1 and 5 microg/cm(2) BC induced a profound cell cycle delay, and no metaphases were observed. The spectrum of damage included chromatid and chromosome-type lesions consistent with mechanistic events associated with the activation of oncogenes and inactivation of tumor suppressor genes. Overall the data indicate that BC is cytotoxic and genotoxic to human lung cells."
647215,Williams et al. 1994,The EPC approach to estimating safety from exposure to environmental chemicals,"Reference doses (RfDs) and reference concentrations (RfCs) developed by the United States Environmental Protection Agency (USEPA) are typically used in the quantitation of risk of potential adverse human health effects from exposure to environmental chemicals. For a large number of chemicals, however, USEPA RfDs and RfCs have not yet been determined. Thus, for risk assessments that involve a large number of chemicals, there is insufficient toxicity information with which to evaluate potential adverse human health effects for all chemicals present at a particular site. Due to this insufficiency, the risk assessor must either (1) ignore potential exposures on the assumption that omitting these exposures does not significantly alter decisions concerning the remediation of the site or (2) undertake a lengthy and costly analysis to generate the necessary RfDs or RfCs. A potential solution to this problem is to develop estimated permissible concentrations (EPCs), values which represent permissible environmental concentrations or related acceptable daily dosages derived from occupational exposure limits. In the present analysis, acceptable daily dosages determined using the EPC method were compared to USEPA RfDs or RfCs which were converted to dosages based on standard exposure assumptions. Based on a comparative analysis of EPCs and USEPA reference values for 103 chemicals, it was found that EPC daily dosages represent a reasonably conservative surrogate value when USEPA or state reference values are unavailable. Given that there are hundreds of chemicals with occupational exposure limits but no state or USEPA reference values, acceptance of the EPC methodology would provide an interim solution for the problem of insufficient toxicity information for a substantial number of environmental chemical contaminants.","The EPC approach to estimating safety from exposure to environmental chemicals Abs: Reference doses (RfDs) and reference concentrations (RfCs) developed by the United States Environmental Protection Agency (USEPA) are typically used in the quantitation of risk of potential adverse human health effects from exposure to environmental chemicals. For a large number of chemicals, however, USEPA RfDs and RfCs have not yet been determined. Thus, for risk assessments that involve a large number of chemicals, there is insufficient toxicity information with which to evaluate potential adverse human health effects for all chemicals present at a particular site. Due to this insufficiency, the risk assessor must either (1) ignore potential exposures on the assumption that omitting these exposures does not significantly alter decisions concerning the remediation of the site or (2) undertake a lengthy and costly analysis to generate the necessary RfDs or RfCs. A potential solution to this problem is to develop estimated permissible concentrations (EPCs), values which represent permissible environmental concentrations or related acceptable daily dosages derived from occupational exposure limits. In the present analysis, acceptable daily dosages determined using the EPC method were compared to USEPA RfDs or RfCs which were converted to dosages based on standard exposure assumptions. Based on a comparative analysis of EPCs and USEPA reference values for 103 chemicals, it was found that EPC daily dosages represent a reasonably conservative surrogate value when USEPA or state reference values are unavailable. Given that there are hundreds of chemicals with occupational exposure limits but no state or USEPA reference values, acceptance of the EPC methodology would provide an interim solution for the problem of insufficient toxicity information for a substantial number of environmental chemical contaminants."
647155,Versteeg et al. 1997,Ceriodaphnia and daphnia: A comparison of their sensitivity to xenobiotics and utility as a test species,"A comparison between Ceriodaphnia sp. and other Cladoceran species including Daphnia magna and D. pulex was made in terms of their life history, geographical distribution, available acute and chronic toxicity test methods and their sensitivity to compounds. Standardized methods currently exist to conduct acute and chronic toxicity tests with C. dubia and this species has received considerable attention in North America. Rewons for this attention include the taxonomic closeness to D. magna, distribution throughout North America, relatively short duration of chronic reproductive toxicity tests (seven days), and Ceriodaphnia's sensitivity. Our review of the literature demonstrates the pandemic distribution of Ceriodaphnia (Europe, Asia, and North America included), the ecological importance of Ceriodaphnia species in freshwater plankton communities, and comparative acute and chronic sensitivity to a broad array of compounds and effluents.","Ceriodaphnia and daphnia: A comparison of their sensitivity to xenobiotics and utility as a test species Abs: A comparison between Ceriodaphnia sp. and other Cladoceran species including Daphnia magna and D. pulex was made in terms of their life history, geographical distribution, available acute and chronic toxicity test methods and their sensitivity to compounds. Standardized methods currently exist to conduct acute and chronic toxicity tests with C. dubia and this species has received considerable attention in North America. Rewons for this attention include the taxonomic closeness to D. magna, distribution throughout North America, relatively short duration of chronic reproductive toxicity tests (seven days), and Ceriodaphnia's sensitivity. Our review of the literature demonstrates the pandemic distribution of Ceriodaphnia (Europe, Asia, and North America included), the ecological importance of Ceriodaphnia species in freshwater plankton communities, and comparative acute and chronic sensitivity to a broad array of compounds and effluents."
646017,Namasivayam and  Sangeetha 2006,"Recycling of agricultural solid waste, coir pith: removal of anions, heavy metals, organics and dyes from water by adsorption onto ZnCl2 activated coir pith carbon","The abundant lignocellulosic agricultural waste, coir pith is used to develop ZnCl(2) activated carbon and applied to the removal of toxic anions, heavy metals, organic compounds and dyes from water. Sorption of inorganic anions such as nitrate, thiocyanate, selenite, chromium(VI), vanadium(V), sulfate, molybdate, phosphate and heavy metals such as nickel(II) and mercury(II) has been studied. Removal of organics such as resorcinol, 4-nitrophenol, catechol, bisphenol A, 2-aminophenol, quinol, O-cresol, phenol and 2-chlorophenol has also been investigated. Uptake of acidic dyes such as acid brilliant blue, acid violet, basic dyes such as methylene blue, rhodamine B, direct dyes such as direct red 12B, congo red and reactive dyes such as procion red, procion orange were also examined to assess the possible use of the adsorbent for the treatment of contaminated ground water. Favorable conditions for maximum removal of all adsorbates at the adsorbate concentration of 20 mg/L were used. Results show that ZnCl(2) activated coir pith carbon is effective for the removal of toxic pollutants from water.","Recycling of agricultural solid waste, coir pith: removal of anions, heavy metals, organics and dyes from water by adsorption onto ZnCl2 activated coir pith carbon Abs: The abundant lignocellulosic agricultural waste, coir pith is used to develop ZnCl(2) activated carbon and applied to the removal of toxic anions, heavy metals, organic compounds and dyes from water. Sorption of inorganic anions such as nitrate, thiocyanate, selenite, chromium(VI), vanadium(V), sulfate, molybdate, phosphate and heavy metals such as nickel(II) and mercury(II) has been studied. Removal of organics such as resorcinol, 4-nitrophenol, catechol, bisphenol A, 2-aminophenol, quinol, O-cresol, phenol and 2-chlorophenol has also been investigated. Uptake of acidic dyes such as acid brilliant blue, acid violet, basic dyes such as methylene blue, rhodamine B, direct dyes such as direct red 12B, congo red and reactive dyes such as procion red, procion orange were also examined to assess the possible use of the adsorbent for the treatment of contaminated ground water. Favorable conditions for maximum removal of all adsorbates at the adsorbate concentration of 20 mg/L were used. Results show that ZnCl(2) activated coir pith carbon is effective for the removal of toxic pollutants from water."
645963,Kong 1998,Metal Toxicity on the Dechlorination of Monochlorophenols in Fresh and Acclimated Anaerobic Sediment Slurries,Investigates metal toxicity on the dechlorination of monochlorophenols in fresh and acclimated anaerobic sediment slurries. Dechlorination methods; Inhibition of dechlorination; Inhibitory effects of specific metals; Role of chlorophenols.,Metal Toxicity on the Dechlorination of Monochlorophenols in Fresh and Acclimated Anaerobic Sediment Slurries Abs: Investigates metal toxicity on the dechlorination of monochlorophenols in fresh and acclimated anaerobic sediment slurries. Dechlorination methods; Inhibition of dechlorination; Inhibitory effects of specific metals; Role of chlorophenols.
645194,Sumida et al. 2005,On-line preconcentration using dual mini-columns for the speciation of chromium(III) and chromium(VI) and its application to water samples as studied by inductively coupled plasma-atomic emission spectrometry,"On-line preconcentration system for the selective, sensitive and simultaneous determination of chromium species was investigated. Dual mini-columns containing chelating resin were utilized for the speciation and preconcentration of Cr(III) and Cr(VI) in water samples. In this system, Cr(III) was collected on first column packed with iminodiacetate resin. Cr(VI) in the effluent from the first column was reduced to Cr(III), which was collected on the second column packed with iminodiacetate resin. Hydroxyammonium chloride was examined as a potential reducing agent for Cr(VI) to Cr(III). The effects of pH, sample flow rate, column length, and interfering ions on the recoveries of Cr(III) were carefully studied. Five millilitres of a sample solution was introduced into the system. The collected species were then sequentially washed by 1M ammonium acetate, eluted by 2M nitric acid and measured by ICP-AES. The detection limit for Cr(III) and Cr(VI) was 0.08 and 0.15mugl(-1), respectively. The total analysis time was about 9.4min. The developed method was successfully applied to the speciation of chromium in river, tap water and wastewater samples with satisfied results.","On-line preconcentration using dual mini-columns for the speciation of chromium(III) and chromium(VI) and its application to water samples as studied by inductively coupled plasma-atomic emission spectrometry Abs: On-line preconcentration system for the selective, sensitive and simultaneous determination of chromium species was investigated. Dual mini-columns containing chelating resin were utilized for the speciation and preconcentration of Cr(III) and Cr(VI) in water samples. In this system, Cr(III) was collected on first column packed with iminodiacetate resin. Cr(VI) in the effluent from the first column was reduced to Cr(III), which was collected on the second column packed with iminodiacetate resin. Hydroxyammonium chloride was examined as a potential reducing agent for Cr(VI) to Cr(III). The effects of pH, sample flow rate, column length, and interfering ions on the recoveries of Cr(III) were carefully studied. Five millilitres of a sample solution was introduced into the system. The collected species were then sequentially washed by 1M ammonium acetate, eluted by 2M nitric acid and measured by ICP-AES. The detection limit for Cr(III) and Cr(VI) was 0.08 and 0.15mugl(-1), respectively. The total analysis time was about 9.4min. The developed method was successfully applied to the speciation of chromium in river, tap water and wastewater samples with satisfied results."
643932,Nickens et al. 2010,Chromium genotoxicity: A double-edged sword,"Certain forms of hexavalent chromium [Cr(VI)] are known respiratory carcinogens that induce a broad spectrum of DNA damage. Cr(VI)-carcinogenesis may be initiated or promoted through several mechanistic processes including, the intracellular metabolic reduction of Cr(VI) producing chromium species capable of interacting with DNA to yield genotoxic and mutagenic effects, Cr(VI)-induced inflammatory/immunological responses, and alteration of survival signaling pathways. Cr(VI) enters the cell through non-specific anion channels, and is metabolically reduced by agents including ascorbate, glutathione, and cysteine to Cr(V), Cr(IV), and Cr(III). Cr(III) has a weak membrane permeability capacity and is unable to cross the cell membrane, thereby trapping it within the cell where it can bind to DNA and produce genetic damage leading to genomic instability. Structural genetic lesions produced by the intracellular reduction of Cr(VI) include DNA adducts, DNA-strand breaks, DNA-protein crosslinks, oxidized bases, abasic sites, and DNA inter- and intrastrand crosslinks. The damage induced by Cr(VI) can lead to dysfunctional DNA replication and transcription, aberrant cell cycle checkpoints, dysregulated DNA repair mechanisms, microsatelite instability, inflammatory responses, and the disruption of key regulatory gene networks responsible for the balance of cell survival and cell death, which may all play an important role in Cr(VI) carcinogenesis. Several lines of evidence have indicated that neoplastic progression is a result of consecutive genetic/epigenetic changes that provide cellular survival advantages, and ultimately lead to the conversion of normal human cells to malignant cancer cells. This review is based on studies that provide a glimpse into Cr(VI) carcinogenicity via mechanisms including Cr(VI)-induced death-resistance, the involvement of DNA repair mechanisms in survival after chromium exposure, and the activation of survival signaling cascades in response to Cr(VI) genotoxicity.","Chromium genotoxicity: A double-edged sword Abs: Certain forms of hexavalent chromium [Cr(VI)] are known respiratory carcinogens that induce a broad spectrum of DNA damage. Cr(VI)-carcinogenesis may be initiated or promoted through several mechanistic processes including, the intracellular metabolic reduction of Cr(VI) producing chromium species capable of interacting with DNA to yield genotoxic and mutagenic effects, Cr(VI)-induced inflammatory/immunological responses, and alteration of survival signaling pathways. Cr(VI) enters the cell through non-specific anion channels, and is metabolically reduced by agents including ascorbate, glutathione, and cysteine to Cr(V), Cr(IV), and Cr(III). Cr(III) has a weak membrane permeability capacity and is unable to cross the cell membrane, thereby trapping it within the cell where it can bind to DNA and produce genetic damage leading to genomic instability. Structural genetic lesions produced by the intracellular reduction of Cr(VI) include DNA adducts, DNA-strand breaks, DNA-protein crosslinks, oxidized bases, abasic sites, and DNA inter- and intrastrand crosslinks. The damage induced by Cr(VI) can lead to dysfunctional DNA replication and transcription, aberrant cell cycle checkpoints, dysregulated DNA repair mechanisms, microsatelite instability, inflammatory responses, and the disruption of key regulatory gene networks responsible for the balance of cell survival and cell death, which may all play an important role in Cr(VI) carcinogenesis. Several lines of evidence have indicated that neoplastic progression is a result of consecutive genetic/epigenetic changes that provide cellular survival advantages, and ultimately lead to the conversion of normal human cells to malignant cancer cells. This review is based on studies that provide a glimpse into Cr(VI) carcinogenicity via mechanisms including Cr(VI)-induced death-resistance, the involvement of DNA repair mechanisms in survival after chromium exposure, and the activation of survival signaling cascades in response to Cr(VI) genotoxicity."
643931,Liu and  Shi 2001,In vivo reduction of chromium (VI) and its related free radical generation,"Chromium (VI) compounds are widely recognized as human carcinogens. Extensive studies in vitro and in model systems indicate that the reactive intermediate, Cr (V), generated by cellular reduction of Cr (VI), is likely the candidate for the ultimate carcinogenic form of chromium compounds. Here we review our current understanding of the in vivo reduction of Cr (VI) and its related free radical generation. Our results demonstrate that Cr (V) is indeed generated from the reduction of Cr (VI) in vivo, and that Cr (V) thus formed can mediate the generation of free radicals. Cr (V) and its related free radicals are very likely to be involved in the mechanism of Cr (VI)-induced toxicity and carcinogenesis. These studies also illustrate that in vivo EPR spectroscopy and magnetic resonance imaging can be very useful and powerful tools for studying paramagnetic metal ions in chemical and biochemical reactions occurring in intact animals.","In vivo reduction of chromium (VI) and its related free radical generation Abs: Chromium (VI) compounds are widely recognized as human carcinogens. Extensive studies in vitro and in model systems indicate that the reactive intermediate, Cr (V), generated by cellular reduction of Cr (VI), is likely the candidate for the ultimate carcinogenic form of chromium compounds. Here we review our current understanding of the in vivo reduction of Cr (VI) and its related free radical generation. Our results demonstrate that Cr (V) is indeed generated from the reduction of Cr (VI) in vivo, and that Cr (V) thus formed can mediate the generation of free radicals. Cr (V) and its related free radicals are very likely to be involved in the mechanism of Cr (VI)-induced toxicity and carcinogenesis. These studies also illustrate that in vivo EPR spectroscopy and magnetic resonance imaging can be very useful and powerful tools for studying paramagnetic metal ions in chemical and biochemical reactions occurring in intact animals."
635074,Steele et al. 1989,Evaluation of a rat tracheal epithelial cell culture assay system to identify respiratory carcinogens,"To evaluate a short-term epithelial cell assay system to detect respiratory carcinogens, primary cultures of rat tracheal epithelial cells were exposed to a series of 17 compounds and scored for morphologically transformed cell colonies 28 days later. The test compounds included known carcinogens and noncarcinogens in volatile or liquids form. Tracheal epithelial cells were isolated from F344 rats, plated onto collagen-coated dishes, and exposed to the test compounds on day 1 for 24 hours. At day 30 the cultures were fixed, stained, and scored for colonies having a density greater than 1,300 cells/min2. With standardized protocols, such colonies are very infrequent in media and solvent control cultures. Concentration levels for each chemical were chosen over a range from nontoxic to toxic levels. Highly positive compounds in this assay included benzo(a)pyrene, benzo(l)acean-thyrlene, 3-methylcholanthrene, and formaldehyde. Compounds which were negative in this assay included pyrene, benzo(e)pyrene, and 4-nitroquinoline-N-oxide. Examining the concordance of in vitro results with whole animal carcinogenesis studies revealed an accuracy of 88% with one false-positive and one false-negative compound. The results of these studies indicate that the rat tracheal epithelial cell assay may be useful in identifying potential respiratory carcinogens in our environment.","Evaluation of a rat tracheal epithelial cell culture assay system to identify respiratory carcinogens Abs: To evaluate a short-term epithelial cell assay system to detect respiratory carcinogens, primary cultures of rat tracheal epithelial cells were exposed to a series of 17 compounds and scored for morphologically transformed cell colonies 28 days later. The test compounds included known carcinogens and noncarcinogens in volatile or liquids form. Tracheal epithelial cells were isolated from F344 rats, plated onto collagen-coated dishes, and exposed to the test compounds on day 1 for 24 hours. At day 30 the cultures were fixed, stained, and scored for colonies having a density greater than 1,300 cells/min2. With standardized protocols, such colonies are very infrequent in media and solvent control cultures. Concentration levels for each chemical were chosen over a range from nontoxic to toxic levels. Highly positive compounds in this assay included benzo(a)pyrene, benzo(l)acean-thyrlene, 3-methylcholanthrene, and formaldehyde. Compounds which were negative in this assay included pyrene, benzo(e)pyrene, and 4-nitroquinoline-N-oxide. Examining the concordance of in vitro results with whole animal carcinogenesis studies revealed an accuracy of 88% with one false-positive and one false-negative compound. The results of these studies indicate that the rat tracheal epithelial cell assay may be useful in identifying potential respiratory carcinogens in our environment."
632551,Parent et al. 2000,Occupational risk factors for renal cell carcinoma in Montreal,"BACKGROUND: Little is known about the role of workplace exposures on the risk of renal cell cancer. METHODS: A population-based case-control study was undertaken in Montreal to assess the association between hundreds of occupational circumstances and several cancer sites, including the kidney. A total of 142 male patients with pathologically confirmed renal cell carcinoma, 1900 controls with cancer at other sites and 533 population-based controls were interviewed. Detailed job histories and relevant data on potential confounders were obtained. A group of chemists-hygienists evaluated each job reported and translated them into a history of occupational exposures using a checklist of 294 substances. Multivariate logistic regression models using either population, cancer controls, or a pool of both groups were used to estimate odds ratios. RESULTS: There were some indications of excess risks among printers, nursery workers (gardening), aircraft mechanics, farmers, and horticulturists, as well as in the following industries: printing-related services, defense services, wholesale trade, and retail trade. Notwithstanding the low precision of many of the odds ratio estimates, the following workplace exposures showed some evidence of excess risk: chromium compounds, chromium (VI) compounds, inorganic acid solutions, styrene-butadiene rubber, ozone, hydrogen sulphide, ultraviolet radiation, hair dust, felt dust, jet fuel engine emissions, jet fuel, aviation gasoline, phosphoric acid and inks. CONCLUSIONS: For most of these associations there exist no, or very little, previous data. Some associations provide suggestive evidence for further studies.","Occupational risk factors for renal cell carcinoma in Montreal Abs: BACKGROUND: Little is known about the role of workplace exposures on the risk of renal cell cancer. METHODS: A population-based case-control study was undertaken in Montreal to assess the association between hundreds of occupational circumstances and several cancer sites, including the kidney. A total of 142 male patients with pathologically confirmed renal cell carcinoma, 1900 controls with cancer at other sites and 533 population-based controls were interviewed. Detailed job histories and relevant data on potential confounders were obtained. A group of chemists-hygienists evaluated each job reported and translated them into a history of occupational exposures using a checklist of 294 substances. Multivariate logistic regression models using either population, cancer controls, or a pool of both groups were used to estimate odds ratios. RESULTS: There were some indications of excess risks among printers, nursery workers (gardening), aircraft mechanics, farmers, and horticulturists, as well as in the following industries: printing-related services, defense services, wholesale trade, and retail trade. Notwithstanding the low precision of many of the odds ratio estimates, the following workplace exposures showed some evidence of excess risk: chromium compounds, chromium (VI) compounds, inorganic acid solutions, styrene-butadiene rubber, ozone, hydrogen sulphide, ultraviolet radiation, hair dust, felt dust, jet fuel engine emissions, jet fuel, aviation gasoline, phosphoric acid and inks. CONCLUSIONS: For most of these associations there exist no, or very little, previous data. Some associations provide suggestive evidence for further studies."
632392,Mccarthy et al. 2009,Characterization of the chronic risk and hazard of hazardous air pollutants in the United States using ambient monitoring data,"BACKGROUND: Ambient measurements of hazardous air pollutants (air toxics) have been used to validate model-predicted concentrations of air toxics but have not been used to perform risk screening at the national level. OBJECTIVES: We used ambient concentrations of routinely measured air toxics to determine the relative importance of individual air toxics for chronic cancer and noncancer exposures. METHODS: We compiled 3-year averages for ambient measurement of air toxics collected at monitoring locations in the United States from 2003 through 2005. We then used national distributions of risk-weighted concentrations to identify the air toxics of most concern. RESULTS: Concentrations of benzene, carbon tetrachloride, arsenic, 1,3-butadiene, and acetaldehyde were above the 10(-6) cancer risk level at most sites nationally with a high degree of confidence. Concentrations of tetrachloroethylene, ethylene oxide, acrylonitrile, and 1,4-dichlorobenzene were also often greater than the 10(-6) cancer risk level, but we have less confidence in the estimated risk associated with these pollutants. Formaldehyde and chromium VI concentrations were either above or below the 10(-6) cancer risk level, depending on the choice of agency-recommended 10(-6) level. The method detection limits of eight additional pollutants were too high to rule out that concentrations were above the 10(-6) cancer risk level. Concentrations of 52 compounds compared with chronic noncancer benchmarks indicated that only acrolein concentrations were greater than the noncancer reference concentration at most monitoring sites. CONCLUSIONS: Most pollutants with national site-level averages greater than health benchmarks were also pollutants of concern identified in modeled national-scale risk assessments. Current monitoring networks need more sensitive ambient measurement techniques to better characterize the air toxics problem in the United States.","Characterization of the chronic risk and hazard of hazardous air pollutants in the United States using ambient monitoring data Abs: BACKGROUND: Ambient measurements of hazardous air pollutants (air toxics) have been used to validate model-predicted concentrations of air toxics but have not been used to perform risk screening at the national level. OBJECTIVES: We used ambient concentrations of routinely measured air toxics to determine the relative importance of individual air toxics for chronic cancer and noncancer exposures. METHODS: We compiled 3-year averages for ambient measurement of air toxics collected at monitoring locations in the United States from 2003 through 2005. We then used national distributions of risk-weighted concentrations to identify the air toxics of most concern. RESULTS: Concentrations of benzene, carbon tetrachloride, arsenic, 1,3-butadiene, and acetaldehyde were above the 10(-6) cancer risk level at most sites nationally with a high degree of confidence. Concentrations of tetrachloroethylene, ethylene oxide, acrylonitrile, and 1,4-dichlorobenzene were also often greater than the 10(-6) cancer risk level, but we have less confidence in the estimated risk associated with these pollutants. Formaldehyde and chromium VI concentrations were either above or below the 10(-6) cancer risk level, depending on the choice of agency-recommended 10(-6) level. The method detection limits of eight additional pollutants were too high to rule out that concentrations were above the 10(-6) cancer risk level. Concentrations of 52 compounds compared with chronic noncancer benchmarks indicated that only acrolein concentrations were greater than the noncancer reference concentration at most monitoring sites. CONCLUSIONS: Most pollutants with national site-level averages greater than health benchmarks were also pollutants of concern identified in modeled national-scale risk assessments. Current monitoring networks need more sensitive ambient measurement techniques to better characterize the air toxics problem in the United States."
631194,Mossman 2003,Serial review: Role of reactive oxygen and nitrogen species (ROS/RNS) in lung injury and diseases,"Chronic environmental and occupational exposures to low levels of metals arc associated with increased incidence ofpulmonary and cardiopulmonary diseases. The cellular and molecular mechanisms of action of metals in the lung are unresolved and involve complex pleiotrophic effects. These effects are mediated by direct reaction of the metals with cellular macromolecules and indirect effects of reactive oxygen species generated when cells are exposed to metals. This review focuses on cell signaling pathways activated by two metals, chromium and nickel, that are known to promote a variety of lung diseases, including fibrosis, obstructive disease, and cancer. These signaling pathways are discussed in relation to the inclusion or exclusion of reactive oxygen in mediating cellular activation following metal exposures.","Serial review: Role of reactive oxygen and nitrogen species (ROS/RNS) in lung injury and diseases Abs: Chronic environmental and occupational exposures to low levels of metals arc associated with increased incidence ofpulmonary and cardiopulmonary diseases. The cellular and molecular mechanisms of action of metals in the lung are unresolved and involve complex pleiotrophic effects. These effects are mediated by direct reaction of the metals with cellular macromolecules and indirect effects of reactive oxygen species generated when cells are exposed to metals. This review focuses on cell signaling pathways activated by two metals, chromium and nickel, that are known to promote a variety of lung diseases, including fibrosis, obstructive disease, and cancer. These signaling pathways are discussed in relation to the inclusion or exclusion of reactive oxygen in mediating cellular activation following metal exposures."
631052,Trevisan et al. 1999,Glutamine synthetase activity in rat urine as sensitive marker to detect S3 segment-specific injury of proximal tubule induced by xenobiotics,"The possibility of detecting segment-specific injury of the proximal tubule by means of urinary enzymes was investigated in rats. Urinary glutamine synthetase, an enzyme exclusively localized in the S3 segment, and N-acetyl-beta-D-glucosaminidase, prevalently a S1-S2, but S3 enzyme also, were determined after single treatment with 100 mg/kg body wt. of hexachloro-1:3-butadiene (HCBD; i.p.), toxic for the S3 segment, or 25 mg/kg body wt. of potassium dichromate (s.c.), toxic for the S1-S2 segments. Excretion of total urinary proteins was also measured. In addition, a dose-response relationship was determined between three doses (50, 100 and 200 mg/kg body wt.) of HCBD and glutamine synthetase activity in urine. Glutamine synthetase activity, measured according to a new assay for urine based on modification of methods developed for organs, increased in the urine only when the S3 segment of the proximal tubule was damaged, as demonstrated by histological findings of the kidneys. HCBD caused early excretion of the enzyme related to the necrosis of the S3 segment, whereas potassium dichromate caused a slight increase only when the resulting lesion to this segment (vacuolization) began to develop. On the contrary, N-acetyl-beta-D-glucosaminidase activity showed the peak of excretion 24 and 34 h after treatment with HCBD or potassium dichromate, respectively, according to the histological findings of necrosis of the S3 segment (the former) and vacuolization of the S1-S2 segments (the latter). Excretion of total urinary proteins reached the peak 24 h (HCBD) and 48 h (potassium dichromate) after treatment. HCBD at 200 mg/kg body wt, caused a peak of glutamine synthetase activity in urine 10 h after injection, whereas the peak caused by doses of 50 and 100 mg/kg body wt. occurred 24 h following treatment. The peak of enzyme activity in urine significantly increased with the dose. The results suggest that the measurement of urinary activity of S3 segment-specific enzyme as glutamine synthetase allows us to detect early S3 segment-specific injury of the proximal tubule. In addition, the method for urinary enzyme activity appears sensitive, simple and fast","Glutamine synthetase activity in rat urine as sensitive marker to detect S3 segment-specific injury of proximal tubule induced by xenobiotics Abs: The possibility of detecting segment-specific injury of the proximal tubule by means of urinary enzymes was investigated in rats. Urinary glutamine synthetase, an enzyme exclusively localized in the S3 segment, and N-acetyl-beta-D-glucosaminidase, prevalently a S1-S2, but S3 enzyme also, were determined after single treatment with 100 mg/kg body wt. of hexachloro-1:3-butadiene (HCBD; i.p.), toxic for the S3 segment, or 25 mg/kg body wt. of potassium dichromate (s.c.), toxic for the S1-S2 segments. Excretion of total urinary proteins was also measured. In addition, a dose-response relationship was determined between three doses (50, 100 and 200 mg/kg body wt.) of HCBD and glutamine synthetase activity in urine. Glutamine synthetase activity, measured according to a new assay for urine based on modification of methods developed for organs, increased in the urine only when the S3 segment of the proximal tubule was damaged, as demonstrated by histological findings of the kidneys. HCBD caused early excretion of the enzyme related to the necrosis of the S3 segment, whereas potassium dichromate caused a slight increase only when the resulting lesion to this segment (vacuolization) began to develop. On the contrary, N-acetyl-beta-D-glucosaminidase activity showed the peak of excretion 24 and 34 h after treatment with HCBD or potassium dichromate, respectively, according to the histological findings of necrosis of the S3 segment (the former) and vacuolization of the S1-S2 segments (the latter). Excretion of total urinary proteins reached the peak 24 h (HCBD) and 48 h (potassium dichromate) after treatment. HCBD at 200 mg/kg body wt, caused a peak of glutamine synthetase activity in urine 10 h after injection, whereas the peak caused by doses of 50 and 100 mg/kg body wt. occurred 24 h following treatment. The peak of enzyme activity in urine significantly increased with the dose. The results suggest that the measurement of urinary activity of S3 segment-specific enzyme as glutamine synthetase allows us to detect early S3 segment-specific injury of the proximal tubule. In addition, the method for urinary enzyme activity appears sensitive, simple and fast"
631033,Teschke et al. 1997,Surveillance of nasal and bladder cancer to locate sources of exposure to occupational carcinogens,"OBJECTIVE: To locate sources of occupational exposure to nasal and bladder carcinogens for surveillance follow up in British Columbia, Canada. METHODS: Incident cases of nasal cancer (n = 48), bladder cancer (n = 105), and population based controls (n = 159) matched for sex and age, were interviewed about their jobs, exposures, and smoking histories. Odds ratios (ORs) were calculated for 57 occupational groups with stratified exact methods to control for age, sex, and smoking. RESULTS: Occupational groups at increased risk of nasal cancer included: textile workers (six cases, OR 7.6); miners, drillers, and blasters (six cases, OR 3.5); welders (two cases, OR 3.5); pulp and paper workers (three cases, OR 3.1); and plumbers and pipefitters (two cases, OR 3.0). Nasal cancer ORs were not increased in occupations exposed to wood dust, possibly due to low exposures in local wood industries. Strongly increased risks of bladder cancer were found for sheet metal workers (four cases, OR 5.3), miners (19 cases, OR 4.5), gardeners (six cases, OR 3.7), and hairdressers (three cases, OR 3.2). Among occupations originally considered at risk, the following had increased risks of bladder cancer: painters (four cases, OR 2.8); laundry workers (five cases, OR 2.3); chemical and petroleum workers (15 cases, OR 1.8); machinists (eight cases, OR 1.6); and textile workers (three cases, OR 1.5). CONCLUSIONS: Occupational groups with increased risks and three or more cases with similar duties were selected for surveillance follow up. For nasal cancer, these included textile workers (five were garment makers) and pulp and paper workers (three performed maintenance tasks likely to entail stainless steel welding). For bladder cancer, these included miners (12 worked underground), machinists (five worked in traditional machining), hairdressers (three had applied hair dyes), and laundry workers (three were drycleaners)","Surveillance of nasal and bladder cancer to locate sources of exposure to occupational carcinogens Abs: OBJECTIVE: To locate sources of occupational exposure to nasal and bladder carcinogens for surveillance follow up in British Columbia, Canada. METHODS: Incident cases of nasal cancer (n = 48), bladder cancer (n = 105), and population based controls (n = 159) matched for sex and age, were interviewed about their jobs, exposures, and smoking histories. Odds ratios (ORs) were calculated for 57 occupational groups with stratified exact methods to control for age, sex, and smoking. RESULTS: Occupational groups at increased risk of nasal cancer included: textile workers (six cases, OR 7.6); miners, drillers, and blasters (six cases, OR 3.5); welders (two cases, OR 3.5); pulp and paper workers (three cases, OR 3.1); and plumbers and pipefitters (two cases, OR 3.0). Nasal cancer ORs were not increased in occupations exposed to wood dust, possibly due to low exposures in local wood industries. Strongly increased risks of bladder cancer were found for sheet metal workers (four cases, OR 5.3), miners (19 cases, OR 4.5), gardeners (six cases, OR 3.7), and hairdressers (three cases, OR 3.2). Among occupations originally considered at risk, the following had increased risks of bladder cancer: painters (four cases, OR 2.8); laundry workers (five cases, OR 2.3); chemical and petroleum workers (15 cases, OR 1.8); machinists (eight cases, OR 1.6); and textile workers (three cases, OR 1.5). CONCLUSIONS: Occupational groups with increased risks and three or more cases with similar duties were selected for surveillance follow up. For nasal cancer, these included textile workers (five were garment makers) and pulp and paper workers (three performed maintenance tasks likely to entail stainless steel welding). For bladder cancer, these included miners (12 worked underground), machinists (five worked in traditional machining), hairdressers (three had applied hair dyes), and laundry workers (three were drycleaners)"
629488,Storer et al. 1996,Revalidation of the in vitro alkaline elution/rat hepatocyte assay for DNA damage: Improved criteria for assessment of cytotoxicity and genotoxicity and results for 81 compounds,"The in vitro alkaline elution/rat hepatocyte assay is a sensitive assay for genotoxicity, measured as DNA strand breaks induced in primary cultures of rat hepatocytes after 3-h treatments with test compounds. Since DNA degradation can be rapid and extensive in dead and/or dying cells, the original criteria for a positive result in the assay were that a compound induce a 3.0-fold or greater increase in the elution slope (for the terminal phase of alkaline elution from 3 to 9 h) in the absence of significant cytotoxicity (defined as relative cell viability of less than 70% by trypan blue dye exclusion; TBDE). Recently we have shown that false-positive results can still be obtained due to cytotoxicity when loss of membrane integrity is a late event in toxic cell death relative to the induction of endonucleolytic DNA degradation. To improve the ability of the assay to discriminate between genotoxic vs. cytotoxic effects of chemicals, we have evaluated additional assays of cytotoxicity including cell adenosine triphosphate (ATP) and potassium (K+) content, tetrazolium dye reduction (MTT), TBDE after a further 3-h recovery incubation without test chemicals (delayed toxicity), cell blebbing and endonucleolytic DNA degradation (double-strand breaks; DSBs) assessed by pulsed-field gel electrophoresis (PFGE). We have also evaluated 2 parameters derived from the elution data which can indicate extensive, cytotoxicity-induced DNA degradation: the fraction of the DNA recovered in the neutral lysis/rinse fraction and the gamma-intercept of the extrapolation of the 3-9-h segment of the elution curve. Twenty-eight rodent non-carcinogens that are negative (or inconclusive) in the Ames assay with no, or limited, other evidence of genotoxicity, and 33 genotoxins, most of which are also carcinogens, were evaluated. The results showed that DNA degradation as measured by a 1-h PACE (Programmed Autonomously Controlled Electrodes)/PFGE assay was a sensitive indicator of cytotoxicity which correlated well with results of the other cytotoxicity indicators. The delayed TBDE (after a 3-h recovery), intracellular potassium and ATP assays as well as the gamma-intercept parameter were also shown to be sensitive and in some cases complementary measures of cytotoxicity. Using new criteria based on these data of an induced slope (treatment slope-negative control slope) of 0.020 for the 3- to 9-h elution period and cytotoxicity limits of 70% relative viability for the delayed TBDE assay and 50% for intracellular ATP content, the assay scores the genotoxicity of these 61 reference compounds with an overall accuracy of 92%. Test results using these new criteria are provided for an additional 20 compounds (5 non-genotoxic carcinogens and 15 compounds whose genotoxic and carcinogenic potential are unknown or equivocal).","Revalidation of the in vitro alkaline elution/rat hepatocyte assay for DNA damage: Improved criteria for assessment of cytotoxicity and genotoxicity and results for 81 compounds Abs: The in vitro alkaline elution/rat hepatocyte assay is a sensitive assay for genotoxicity, measured as DNA strand breaks induced in primary cultures of rat hepatocytes after 3-h treatments with test compounds. Since DNA degradation can be rapid and extensive in dead and/or dying cells, the original criteria for a positive result in the assay were that a compound induce a 3.0-fold or greater increase in the elution slope (for the terminal phase of alkaline elution from 3 to 9 h) in the absence of significant cytotoxicity (defined as relative cell viability of less than 70% by trypan blue dye exclusion; TBDE). Recently we have shown that false-positive results can still be obtained due to cytotoxicity when loss of membrane integrity is a late event in toxic cell death relative to the induction of endonucleolytic DNA degradation. To improve the ability of the assay to discriminate between genotoxic vs. cytotoxic effects of chemicals, we have evaluated additional assays of cytotoxicity including cell adenosine triphosphate (ATP) and potassium (K+) content, tetrazolium dye reduction (MTT), TBDE after a further 3-h recovery incubation without test chemicals (delayed toxicity), cell blebbing and endonucleolytic DNA degradation (double-strand breaks; DSBs) assessed by pulsed-field gel electrophoresis (PFGE). We have also evaluated 2 parameters derived from the elution data which can indicate extensive, cytotoxicity-induced DNA degradation: the fraction of the DNA recovered in the neutral lysis/rinse fraction and the gamma-intercept of the extrapolation of the 3-9-h segment of the elution curve. Twenty-eight rodent non-carcinogens that are negative (or inconclusive) in the Ames assay with no, or limited, other evidence of genotoxicity, and 33 genotoxins, most of which are also carcinogens, were evaluated. The results showed that DNA degradation as measured by a 1-h PACE (Programmed Autonomously Controlled Electrodes)/PFGE assay was a sensitive indicator of cytotoxicity which correlated well with results of the other cytotoxicity indicators. The delayed TBDE (after a 3-h recovery), intracellular potassium and ATP assays as well as the gamma-intercept parameter were also shown to be sensitive and in some cases complementary measures of cytotoxicity. Using new criteria based on these data of an induced slope (treatment slope-negative control slope) of 0.020 for the 3- to 9-h elution period and cytotoxicity limits of 70% relative viability for the delayed TBDE assay and 50% for intracellular ATP content, the assay scores the genotoxicity of these 61 reference compounds with an overall accuracy of 92%. Test results using these new criteria are provided for an additional 20 compounds (5 non-genotoxic carcinogens and 15 compounds whose genotoxic and carcinogenic potential are unknown or equivocal)."
629377,Pauli and  Berger 1997,"Toxicological comparisons of Tetrahymena species, end points and growth media: Supplementary investigations to the pilot ring test","Parallel to an international Pilot Ring Test to standardize a mutigeneration test protocol with the protozoon Tetrahymena pyriformis supplementary investigations were made. Effects on growth rate and 46 h population density were measured using an extended set of 12 chemicals, a further Tetrahymena-species (T. thermophila) and 4 different media (axenic and bacteria based). Results are compared for sensitivity with effects on additional end points (chemosensory response, respiration and vitality). Both species exhibit similar sensitivity towards the chemicals. In some cases the media composition influenced the toxic potential of chemicals. Both growth parameters proved to be a sensitive integral end point for toxicological studies, confirming the one point, photometric measurement of population density after 46 hours in axenic (preferably proteose peptone-) medium an obvious choice for a standard test procedure.","Toxicological comparisons of Tetrahymena species, end points and growth media: Supplementary investigations to the pilot ring test Abs: Parallel to an international Pilot Ring Test to standardize a mutigeneration test protocol with the protozoon Tetrahymena pyriformis supplementary investigations were made. Effects on growth rate and 46 h population density were measured using an extended set of 12 chemicals, a further Tetrahymena-species (T. thermophila) and 4 different media (axenic and bacteria based). Results are compared for sensitivity with effects on additional end points (chemosensory response, respiration and vitality). Both species exhibit similar sensitivity towards the chemicals. In some cases the media composition influenced the toxic potential of chemicals. Both growth parameters proved to be a sensitive integral end point for toxicological studies, confirming the one point, photometric measurement of population density after 46 hours in axenic (preferably proteose peptone-) medium an obvious choice for a standard test procedure."
629313,Matsumoto et al. 1994,Treatment systems: Physicochemical processes,"Part of Water Environment Research's annual Literature Review. The physicochemical processes subsection of the treatment systems section of the review contains segments on general issues, precipitation, coagulation/flocculation, sedimentation and flotation, filtration, membrane processes, sorption of inorganics, sorption of organics, oxidation/reduction, air stripping, and mixed processes.","Treatment systems: Physicochemical processes Abs: Part of Water Environment Research's annual Literature Review. The physicochemical processes subsection of the treatment systems section of the review contains segments on general issues, precipitation, coagulation/flocculation, sedimentation and flotation, filtration, membrane processes, sorption of inorganics, sorption of organics, oxidation/reduction, air stripping, and mixed processes."
629301,Marshall et al. 1995,Analytic study to evaluate associations between hazardous waste sites and birth defects,"A study was conducted to evaluate the risk of two types of birth defects (central nervous system and musculoskeletal defects) associated with mothers' exposure to solvents, metals, and pesticides through residence near hazardous waste sites. The only environmental factor showing a statistically significant elevation in risk was living within one mile of industrial or commercial facilities emitting solvents into the air. Residence near these facilities showed elevated risk for central nervous system defects but no elevated risks for musculoskeletal defects.","Analytic study to evaluate associations between hazardous waste sites and birth defects Abs: A study was conducted to evaluate the risk of two types of birth defects (central nervous system and musculoskeletal defects) associated with mothers' exposure to solvents, metals, and pesticides through residence near hazardous waste sites. The only environmental factor showing a statistically significant elevation in risk was living within one mile of industrial or commercial facilities emitting solvents into the air. Residence near these facilities showed elevated risk for central nervous system defects but no elevated risks for musculoskeletal defects."
629263,Larsen et al. 1997,Progress in an ecotoxicological standard protocol with protozoa: results from a pilot ring test with Tetrahymena pyriformis,"The aim of this project was to develop a standardized multigeneration growth inhibition test protocol to assess the sublethal effects of industrial chemicals and pesticides on protozoans. The inclusion of a test with protozoa would be an ecologically relevant supplement to the existing basic set in aquatic toxicity testing. The different aspects evaluated in the pilot ring study include: two media, two volumes, two end points and two different methods to measure the cell density. Taking into account the aim to develop a simple, sensitive, reproducible and cost effective test, recommendations are made for a standardized protocol.","Progress in an ecotoxicological standard protocol with protozoa: results from a pilot ring test with Tetrahymena pyriformis Abs: The aim of this project was to develop a standardized multigeneration growth inhibition test protocol to assess the sublethal effects of industrial chemicals and pesticides on protozoans. The inclusion of a test with protozoa would be an ecologically relevant supplement to the existing basic set in aquatic toxicity testing. The different aspects evaluated in the pilot ring study include: two media, two volumes, two end points and two different methods to measure the cell density. Taking into account the aim to develop a simple, sensitive, reproducible and cost effective test, recommendations are made for a standardized protocol."
629174,Hall et al. 1995,The influence of salinity on the toxicity of various classes of chemicals to aquatic biota,"The objective of this study was to review all available aquatic toxicity literature regarding the effects of salinity on the toxicity of various classes of inorganic and organic chemicals. Toxicity data for studies in which toxicity was assessed at various salinities were organized by chemical classes and trophic groups. Seventy percent of the studies were conducted with either crustaceans or fish. The other 30% were with mollusks, annelids, zooplankton, bacteria, phytoplankton, or fungi. Results from 173 data entries showed that negative correlations (toxicity increasing with decreasing salinity) were reported most frequently (55%), followed by no correlations (27%) and positive correlations (18%). The toxicity of most metals such as cadmium, chromium, copper, mercury, nickel, and zinc was reported to increase with decreasing salinity. This finding is likely related to the greater bioavailability of the free metal ion (toxic form) at lower salinity conditions. There was generally no consistent trend for the toxicity of most organic chemicals with salinity. The one exception to this was reported with organophosphate insecticides, the toxicity of which appeared to increase with increasing salinity. Physiological characteristics of the various test species were important in determining the toxicity of the various classes of chemicals at a range of salinities. Results from various studies showed that euryhaline species were more resistant to toxic conditions at isosmotic salinities due to minimization of osmotic stress. Specific examples showed that fish were more resistant to toxic chemicals at middle salinities when compared with either lower or higher extremes. Life history and ecology of test species were important factors to consider when interpreting salinity/contaminant interaction data.","The influence of salinity on the toxicity of various classes of chemicals to aquatic biota Abs: The objective of this study was to review all available aquatic toxicity literature regarding the effects of salinity on the toxicity of various classes of inorganic and organic chemicals. Toxicity data for studies in which toxicity was assessed at various salinities were organized by chemical classes and trophic groups. Seventy percent of the studies were conducted with either crustaceans or fish. The other 30% were with mollusks, annelids, zooplankton, bacteria, phytoplankton, or fungi. Results from 173 data entries showed that negative correlations (toxicity increasing with decreasing salinity) were reported most frequently (55%), followed by no correlations (27%) and positive correlations (18%). The toxicity of most metals such as cadmium, chromium, copper, mercury, nickel, and zinc was reported to increase with decreasing salinity. This finding is likely related to the greater bioavailability of the free metal ion (toxic form) at lower salinity conditions. There was generally no consistent trend for the toxicity of most organic chemicals with salinity. The one exception to this was reported with organophosphate insecticides, the toxicity of which appeared to increase with increasing salinity. Physiological characteristics of the various test species were important in determining the toxicity of the various classes of chemicals at a range of salinities. Results from various studies showed that euryhaline species were more resistant to toxic conditions at isosmotic salinities due to minimization of osmotic stress. Specific examples showed that fish were more resistant to toxic chemicals at middle salinities when compared with either lower or higher extremes. Life history and ecology of test species were important factors to consider when interpreting salinity/contaminant interaction data."
628971,Andersen et al. 1999,Work-related cancer in the Nordic countries,"This report presents 20 years` of cancer incidence data by occupational group for the Nordic populations. The study covers the 10 million people aged 25–64 years at the time of the 1970 censuses in Denmark, Finland, Norway, and Sweden, and the 1 million incident cancer cases diagnosed among these people during the subsequent 20 years. The project was undertaken as a cohort study with linkage of individual records based on the personal identification numbers used in all the Nordic countries. In the 1970 censuses, information on occupation for each economically active member of the household was provided in free text in self-administered questionnaires. The data were centrally coded and computerized in the statistical offices. Norway, Sweden, and Finland used the Nordic Classification of Occupations, while Denmark used a national coding scheme. However, all the data could be reclassified into 53 occupational groups and 1 group of economically inactive persons. Person-years at risk were accumulated from 1 January 1971 until the date of emigration, date of death or 31 December 1987 in Denmark, 1989 in Sweden, 1990 in Finland, and 1991 in Norway. The 4 countries all had nationwide registration of incident cancer cases during the entire study period. All incident cancer cases during the individual risk periods were included in the analysis. Despite minor differences between the countries, the International Classification of Diseases, 7th revision, formed the core basis for the diagnostic coding in all 4 countries. For the present study the incident cancer cases have been classified into 35 broad diagnostic groups. The observed number of cancer cases in each group of persons defined by country, gender, and occupation was compared with the expected number calculated from the age-, gender-, and period-specific person-years and the incidence rates for the national population. The result has been presented as a standardized incidence ratio (SIR), defined as the observed number of cases divided by the expected number and multiplied by 100. In the tables of this report, all the SIR values for which the upper limit of the 95% confidence interval is below 100 are printed in green and all those for which the lower limit of the confidence interval is above 100 are printed in red. For all cancers combined, the study showed a wide variation among the men, from an SIR of 79 for farmers to 159 for waiters. The occupations with the highest SIR values also included seamen and workers producing beverages and tobacco. Among the women the SIR values varied from 83 for gardeners to 129 for tobacco workers. Low SIR values were found for farmers and teachers. Outdoor workers such as fishermen and gardeners had the highest risk of lip cancer, while the lowest risk was found among indoor workers such as physicians and artistic workers. Almost all pleural cancers are associated with asbestos exposure. Accordingly, plumbers, welders, mechanics, and seamen were the occupations with the highest risk. There was also an excess risk of pleural cancer in the occupational group of technical, chemical, physical, and biological workers, including, among others, engineers and chemists potentially exposed to asbestos. The wood workers included in the present study had the highest risk of nasal cancer. Most studies of nasal cancer have shown increased risks associated with exposure to wood dust, both for those in furniture making and for those exposed exclusively to soft wood. Nickel refinery workers are also known for their high risk of nasal cancer. In the present study they were included in the occupational group of smelting workers. Lung cancer was the most frequent cancer among men in the present study. Tobacco smoking is the major risk factor for this disease, but occupational exposures also play an important role. Waiters and tobacco workers had the highest risk of lung cancer. Miners and quarry workers also had a high risk of lung cancer, which may be related to their exposure to silica dust and radon daughters. Among women, tobacco workers had the highest risk of lung cancer and farmers and gardeners had the lowest risk. Waiters had the highest risk of bladder cancer for men, and they were one of the groups at highest risk among the women. Chimney sweeps and male hairdressers also had high SIR values for bladder cancer. Chimney sweeps are exposed to polycyclic aromatic hydrocarbons from chimney soot, and the carcinogenicity of these compounds is well documented. Almost all occupational groups with low SIR values for bladder cancer also had low SIR values for lung cancer, groups such as farmers, gardeners, and those working in pedagogical work. Exposure to the known hepatocarcinogens, Hepatitis B virus and aflatoxins is rare in the Nordic countries, and a large proportion of primary liver cancers can therefore be attributed to alcohol consumption. When primary liver cancer was classified by occupation, high risks were found for occupational groups with easy access to alcohol at the workplace or with cultural traditions for high alcohol consumption. Among men, waiters, journalists, cooks, beverage workers, and seamen had the highest risk. The lowest SIR values were found for farmers, forestry workers, teachers, wood workers, and gardeners. The risk of colon cancer has been related to sedentary work. The findings in the present study were in agreement, especially for men with this pattern, as journalists and physicians had the highest risk and outdoor workers such as farmers and forestry workers had the lowest risk. The occupational categories with the highest risks of breast cancer in the present study are accompanied by a university or equivalent education. This pattern is in agreement with a relatively late age at first birth among the well-educated Nordic women from the relevant birth cohorts. Malignant melanoma showed the same strong social gradient as cancers of the colon and breast. The major risk factor for malignant melanoma is intermittent sunlight exposure and sunburns of susceptible persons, which occur particularly during leisure time. The Nordic countries are well known for equity and free and equal access to health care for all citizens. The present study shows that the risk of cancer, even under these circumstances, is highly dependent on the person`s position in society.","Work-related cancer in the Nordic countries Abs: This report presents 20 years` of cancer incidence data by occupational group for the Nordic populations. The study covers the 10 million people aged 25–64 years at the time of the 1970 censuses in Denmark, Finland, Norway, and Sweden, and the 1 million incident cancer cases diagnosed among these people during the subsequent 20 years. The project was undertaken as a cohort study with linkage of individual records based on the personal identification numbers used in all the Nordic countries. In the 1970 censuses, information on occupation for each economically active member of the household was provided in free text in self-administered questionnaires. The data were centrally coded and computerized in the statistical offices. Norway, Sweden, and Finland used the Nordic Classification of Occupations, while Denmark used a national coding scheme. However, all the data could be reclassified into 53 occupational groups and 1 group of economically inactive persons. Person-years at risk were accumulated from 1 January 1971 until the date of emigration, date of death or 31 December 1987 in Denmark, 1989 in Sweden, 1990 in Finland, and 1991 in Norway. The 4 countries all had nationwide registration of incident cancer cases during the entire study period. All incident cancer cases during the individual risk periods were included in the analysis. Despite minor differences between the countries, the International Classification of Diseases, 7th revision, formed the core basis for the diagnostic coding in all 4 countries. For the present study the incident cancer cases have been classified into 35 broad diagnostic groups. The observed number of cancer cases in each group of persons defined by country, gender, and occupation was compared with the expected number calculated from the age-, gender-, and period-specific person-years and the incidence rates for the national population. The result has been presented as a standardized incidence ratio (SIR), defined as the observed number of cases divided by the expected number and multiplied by 100. In the tables of this report, all the SIR values for which the upper limit of the 95% confidence interval is below 100 are printed in green and all those for which the lower limit of the confidence interval is above 100 are printed in red. For all cancers combined, the study showed a wide variation among the men, from an SIR of 79 for farmers to 159 for waiters. The occupations with the highest SIR values also included seamen and workers producing beverages and tobacco. Among the women the SIR values varied from 83 for gardeners to 129 for tobacco workers. Low SIR values were found for farmers and teachers. Outdoor workers such as fishermen and gardeners had the highest risk of lip cancer, while the lowest risk was found among indoor workers such as physicians and artistic workers. Almost all pleural cancers are associated with asbestos exposure. Accordingly, plumbers, welders, mechanics, and seamen were the occupations with the highest risk. There was also an excess risk of pleural cancer in the occupational group of technical, chemical, physical, and biological workers, including, among others, engineers and chemists potentially exposed to asbestos. The wood workers included in the present study had the highest risk of nasal cancer. Most studies of nasal cancer have shown increased risks associated with exposure to wood dust, both for those in furniture making and for those exposed exclusively to soft wood. Nickel refinery workers are also known for their high risk of nasal cancer. In the present study they were included in the occupational group of smelting workers. Lung cancer was the most frequent cancer among men in the present study. Tobacco smoking is the major risk factor for this disease, but occupational exposures also play an important role. Waiters and tobacco workers had the highest risk of lung cancer. Miners and quarry workers also had a high risk of lung cancer, which may be related to their exposure to silica dust and radon daughters. Among women, tobacco workers had the highest risk of lung cancer and farmers and gardeners had the lowest risk. Waiters had the highest risk of bladder cancer for men, and they were one of the groups at highest risk among the women. Chimney sweeps and male hairdressers also had high SIR values for bladder cancer. Chimney sweeps are exposed to polycyclic aromatic hydrocarbons from chimney soot, and the carcinogenicity of these compounds is well documented. Almost all occupational groups with low SIR values for bladder cancer also had low SIR values for lung cancer, groups such as farmers, gardeners, and those working in pedagogical work. Exposure to the known hepatocarcinogens, Hepatitis B virus and aflatoxins is rare in the Nordic countries, and a large proportion of primary liver cancers can therefore be attributed to alcohol consumption. When primary liver cancer was classified by occupation, high risks were found for occupational groups with easy access to alcohol at the workplace or with cultural traditions for high alcohol consumption. Among men, waiters, journalists, cooks, beverage workers, and seamen had the highest risk. The lowest SIR values were found for farmers, forestry workers, teachers, wood workers, and gardeners. The risk of colon cancer has been related to sedentary work. The findings in the present study were in agreement, especially for men with this pattern, as journalists and physicians had the highest risk and outdoor workers such as farmers and forestry workers had the lowest risk. The occupational categories with the highest risks of breast cancer in the present study are accompanied by a university or equivalent education. This pattern is in agreement with a relatively late age at first birth among the well-educated Nordic women from the relevant birth cohorts. Malignant melanoma showed the same strong social gradient as cancers of the colon and breast. The major risk factor for malignant melanoma is intermittent sunlight exposure and sunburns of susceptible persons, which occur particularly during leisure time. The Nordic countries are well known for equity and free and equal access to health care for all citizens. The present study shows that the risk of cancer, even under these circumstances, is highly dependent on the person`s position in society."
628903,Grant 1998,Higher plant assays for the detection of genotoxicity in air polluted environments,"Since the beginning of time pollution has been created by human activities. However, the intensity and the severity of the different kinds of pollution have emerged only in the last few decades and many intricate facets have been revealed. It is gradually being recognized that our health and the ecosystem are being severely affected by environmental chemicals that enter the atmosphere. Plants comprise a large portion of our biosphere and constitute a vital link in the food chain. In this review, types of mutagenic chemicals found both indoor and outdoor are given and several higher plant bioassays for screening and monitoring environmental mutagens are discussed. One plant ideal for monitoring and testing for air pollution is Tradescantia. This species has been used to test for mutagenicity of radioisotope-contaminated air following the Chernobyl nuclear accident and monitoring around nuclear power plants. One of the greatest contributions of plant bioassays will be their continued use for ambient air monitoring and testing for genotoxicity which can be carried out on a global scale.","Higher plant assays for the detection of genotoxicity in air polluted environments Abs: Since the beginning of time pollution has been created by human activities. However, the intensity and the severity of the different kinds of pollution have emerged only in the last few decades and many intricate facets have been revealed. It is gradually being recognized that our health and the ecosystem are being severely affected by environmental chemicals that enter the atmosphere. Plants comprise a large portion of our biosphere and constitute a vital link in the food chain. In this review, types of mutagenic chemicals found both indoor and outdoor are given and several higher plant bioassays for screening and monitoring environmental mutagens are discussed. One plant ideal for monitoring and testing for air pollution is Tradescantia. This species has been used to test for mutagenicity of radioisotope-contaminated air following the Chernobyl nuclear accident and monitoring around nuclear power plants. One of the greatest contributions of plant bioassays will be their continued use for ambient air monitoring and testing for genotoxicity which can be carried out on a global scale."
628586,Sugden et al. 2004,Oxidative activation of the human carcinogen chromate by arsenite: A model for synergistic metal activation leading to oxidative DNA damage,"Human exposure to toxic metals and metalloids in the environment seldom occurs from a single pure compound. Most environmental exposure profiles are heterogeneous with co-exposure occurring coincident with multiple toxic metal species. This co-exposure to metals and metalloids in complex mixtures can result in a synergistic, additive or even depletive toxic response. The complexity of interactions presented by metal mixtures presents a need for convenient and sensitive methods to determine potential toxic responses from such co-exposure. We have studied the reaction between the two commonly associated toxic metals of chromate, Cr(VI), and arsenite, As(III), with regards to the ability of As(III) to reductively activate Cr(VI) to generate oxidative stress and DNA damage. Using a DCF-based fluorescent dye assay we have demonstrated that the redox reaction between As(III) and Cr(VI) yields high valent intermediates of chromium, Cr(V), that are highly oxidizing. This induction of oxidizing potential was dose dependent and did not occur with As(III) or Cr(VI) alone or, with the other major oxidation state of arsenic, arsenate, As(V). The mechanism of oxidation of DCFH to the fluorescent species, DCF, in this reaction was through a direct, metal-based oxidation since addition of radical scavengers did not significantly decrease oxidation of the dye in this system. The addition of a ligand that stabilizes the high valent Cr(V) oxidation state, 2-ethyl-2-hydroxybutyric acid (EHBA), to the chromate and arsenite mixture resulted in an enhancement of DCF fluorescence. The DCF fluorescence observed with the Cr(VI) and As(III) mixture was also found to correlate with oxidative DNA damage as measured by a plasmid nicking assay. These data show how metal-metal interactions in environmental mixtures could result in the synergistic induction of oxidative stress and DNA damage. Further, these data demonstrate the utility of the DCF fluorescence assay as a sensitive method for screening synergistic redox interactions in metal mixtures.","Oxidative activation of the human carcinogen chromate by arsenite: A model for synergistic metal activation leading to oxidative DNA damage Abs: Human exposure to toxic metals and metalloids in the environment seldom occurs from a single pure compound. Most environmental exposure profiles are heterogeneous with co-exposure occurring coincident with multiple toxic metal species. This co-exposure to metals and metalloids in complex mixtures can result in a synergistic, additive or even depletive toxic response. The complexity of interactions presented by metal mixtures presents a need for convenient and sensitive methods to determine potential toxic responses from such co-exposure. We have studied the reaction between the two commonly associated toxic metals of chromate, Cr(VI), and arsenite, As(III), with regards to the ability of As(III) to reductively activate Cr(VI) to generate oxidative stress and DNA damage. Using a DCF-based fluorescent dye assay we have demonstrated that the redox reaction between As(III) and Cr(VI) yields high valent intermediates of chromium, Cr(V), that are highly oxidizing. This induction of oxidizing potential was dose dependent and did not occur with As(III) or Cr(VI) alone or, with the other major oxidation state of arsenic, arsenate, As(V). The mechanism of oxidation of DCFH to the fluorescent species, DCF, in this reaction was through a direct, metal-based oxidation since addition of radical scavengers did not significantly decrease oxidation of the dye in this system. The addition of a ligand that stabilizes the high valent Cr(V) oxidation state, 2-ethyl-2-hydroxybutyric acid (EHBA), to the chromate and arsenite mixture resulted in an enhancement of DCF fluorescence. The DCF fluorescence observed with the Cr(VI) and As(III) mixture was also found to correlate with oxidative DNA damage as measured by a plasmid nicking assay. These data show how metal-metal interactions in environmental mixtures could result in the synergistic induction of oxidative stress and DNA damage. Further, these data demonstrate the utility of the DCF fluorescence assay as a sensitive method for screening synergistic redox interactions in metal mixtures."
628583,Ikarashi et al. 1996,"Evaluation of skin sensitization potential of nickel, chromium, titanium and zirconium salts using guinea-pigs and mice","Contact sensitization capacity of four metal salts, nickel sulphate (NiSO4), potassium dichromate (K2Cr2O7), titanium chloride (TiCl4) and zirconium chloride (ZrCl4), was evaluated using guinea-pigs and mice. In the guinea-pig sensitization tests, we set up an injection concentration to 1% for all chemicals, and changed the challenge concentration. Guinea-pigs were sensitized with NiSO4, K2Cr2O7 and TiCl4. Among the test metal salts, K2Cr2O7 showed the highest sensitization rate and strongest skin reactions. ZrCl4 did not cause any sensitization responses under our experimental conditions. Minimum challenge concentration to cause a skin response was < 0.25% for K2Cr2O7, 0.5% for NiSO4 and 2% for TiCl4, respectively. A sensitive mouse lymph node assay (SLNA) also determined NiSO4 and K2Cr2O7 as a sensitizer. In the SLNA, TiCl4 caused mild lymph node responses, but was classified as a non-sensitizer as well as ZrCl4. Considering these results, the order of sensitization potential was K2Cr2O7 > NiSO4 > ZrCl4. NiSO4- and K2CrO7-sensitized animals did not show any reactions to ZrCl4 and TiCl4. No cross-reaction among these metal salts was found.","Evaluation of skin sensitization potential of nickel, chromium, titanium and zirconium salts using guinea-pigs and mice Abs: Contact sensitization capacity of four metal salts, nickel sulphate (NiSO4), potassium dichromate (K2Cr2O7), titanium chloride (TiCl4) and zirconium chloride (ZrCl4), was evaluated using guinea-pigs and mice. In the guinea-pig sensitization tests, we set up an injection concentration to 1% for all chemicals, and changed the challenge concentration. Guinea-pigs were sensitized with NiSO4, K2Cr2O7 and TiCl4. Among the test metal salts, K2Cr2O7 showed the highest sensitization rate and strongest skin reactions. ZrCl4 did not cause any sensitization responses under our experimental conditions. Minimum challenge concentration to cause a skin response was < 0.25% for K2Cr2O7, 0.5% for NiSO4 and 2% for TiCl4, respectively. A sensitive mouse lymph node assay (SLNA) also determined NiSO4 and K2Cr2O7 as a sensitizer. In the SLNA, TiCl4 caused mild lymph node responses, but was classified as a non-sensitizer as well as ZrCl4. Considering these results, the order of sensitization potential was K2Cr2O7 > NiSO4 > ZrCl4. NiSO4- and K2CrO7-sensitized animals did not show any reactions to ZrCl4 and TiCl4. No cross-reaction among these metal salts was found."
628271,Upreti et al. 2007,Experimental exposure of arsenic in cultured rat intestinal epithelial cells and cell line: Toxicological consequences,"Arsenic is a naturally occurring metalloid and the drinking water contamination by inorganic arsenic remains a major public health problem. The trivalent arsenic (arsenite) is more toxic than the pentavalent form (arsenate), and is known to cause gastrointestinal toxicity. Specific immortal cell lines are considered to be suitable for toxicity screening and testing of chemicals as they are easy to handle and possess most of the biochemical pathways present in the corresponding cells present in vivo. The present study was designed to evaluate and compare the in vitro toxicity of arsenite on rat intestinal epithelial cell line (IEC-6) and primary cultures of rat intestinal epithelial cells (IEC). To evaluate in vitro toxicity, cultures of IEC and IEC-6 cells were assessed for viability, morphometric analysis, membrane transport enzymes and structural constituents for membrane damage, dehydrogenase activity test for respiratory and energy producing processes and esterase activity test for intra and extra cellular degradation, following the post exposures to arsenite (0-20 ppm). Significantly similar concentration-dependent changes in these toxicity-screening parameters in IEC and IEC-6 were observed. Highest tested concentration of arsenite (20 ppm) was found to be detrimental in both IEC and IEC-6. Furthermore, to evaluate arsenite toxicity in epithelial cells of rat intestine, intestinal loops were filled with arsenite solutions and incubated for 30 min in situ. In situ studies also showed a significant arsenite concentration-dependent decline in epithelial cell membrane transport enzyme activities and total hexose and sialic acid contents. Concomitant release of membrane enzymes, hexose and sialic acid in the intestinal luminal fluid following higher arsenite exposures further indicated partial membrane damage. Similar morphological changes in IEC and IEC-6 were also evident. These findings also suggest that IEC-6 cell lines are suitable for initial screening of gastrointestinal cellular toxicity caused by arsenite.","Experimental exposure of arsenic in cultured rat intestinal epithelial cells and cell line: Toxicological consequences Abs: Arsenic is a naturally occurring metalloid and the drinking water contamination by inorganic arsenic remains a major public health problem. The trivalent arsenic (arsenite) is more toxic than the pentavalent form (arsenate), and is known to cause gastrointestinal toxicity. Specific immortal cell lines are considered to be suitable for toxicity screening and testing of chemicals as they are easy to handle and possess most of the biochemical pathways present in the corresponding cells present in vivo. The present study was designed to evaluate and compare the in vitro toxicity of arsenite on rat intestinal epithelial cell line (IEC-6) and primary cultures of rat intestinal epithelial cells (IEC). To evaluate in vitro toxicity, cultures of IEC and IEC-6 cells were assessed for viability, morphometric analysis, membrane transport enzymes and structural constituents for membrane damage, dehydrogenase activity test for respiratory and energy producing processes and esterase activity test for intra and extra cellular degradation, following the post exposures to arsenite (0-20 ppm). Significantly similar concentration-dependent changes in these toxicity-screening parameters in IEC and IEC-6 were observed. Highest tested concentration of arsenite (20 ppm) was found to be detrimental in both IEC and IEC-6. Furthermore, to evaluate arsenite toxicity in epithelial cells of rat intestine, intestinal loops were filled with arsenite solutions and incubated for 30 min in situ. In situ studies also showed a significant arsenite concentration-dependent decline in epithelial cell membrane transport enzyme activities and total hexose and sialic acid contents. Concomitant release of membrane enzymes, hexose and sialic acid in the intestinal luminal fluid following higher arsenite exposures further indicated partial membrane damage. Similar morphological changes in IEC and IEC-6 were also evident. These findings also suggest that IEC-6 cell lines are suitable for initial screening of gastrointestinal cellular toxicity caused by arsenite."
627931,O'Hara et al. 2006,Chromium (VI) inhibits heme oxygenase-1 expression in vivo and in arsenic-exposed human airway epithelial cells,"Inhaled hexavalent chromium (Cr(VI)) promotes lung injury and pulmonary diseases through poorly defined mechanisms. One hypothesis for this lung pathogenesis is that Cr(VI) silences induction of cytoprotective genes, such as heme oxygenase-1 (HO-1), whose total lung mRNA levels were reduced 21 days after nasal instillation of potassium dichromate in C57BL/6 mice. To investigate the mechanisms for this inhibition, Cr(VI) effects on basal and arsenic (As(III))-induced HO-1 expression were examined in cultured human bronchial epithelial (BEAS-2B) cells. An effect of Cr(VI) on the low basal HO-1 mRNA and protein levels in BEAS-2B cells was not detectible. In contrast, Cr(VI) added to the cells before As(III), but not simultaneously with As(III), attenuated As(III)-induced HO-1 expression. Transient transfection with luciferase reporter gene constructs controlled by the full length ho-1 promoter or deletion mutants demonstrated that this inhibition occurred in the E1 enhancer region containing critical antioxidant response elements (ARE). Cr(VI) pretreatment inhibited As(III)-induced activity of a transiently expressed reporter construct regulated by three ARE tandem repeats. The mechanism for this Cr(VI)-attenuated transactivation appeared to be Cr(VI) reduction of the nuclear levels of the transcription factor Nrf2 and As(III)-stimulated Nrf2 transcriptional complex binding to the ARE cis element. Finally, exposing cells to Cr(VI) prior to co-exposure with As(III) synergized for apoptosis and loss of membrane integrity. These data suggest that Cr(VI) silences induction of ARE-driven genes required for protection from secondary insults. The data also have important implications for understanding the toxic mechanisms of low level, mixed metal exposures in the lung.","Chromium (VI) inhibits heme oxygenase-1 expression in vivo and in arsenic-exposed human airway epithelial cells Abs: Inhaled hexavalent chromium (Cr(VI)) promotes lung injury and pulmonary diseases through poorly defined mechanisms. One hypothesis for this lung pathogenesis is that Cr(VI) silences induction of cytoprotective genes, such as heme oxygenase-1 (HO-1), whose total lung mRNA levels were reduced 21 days after nasal instillation of potassium dichromate in C57BL/6 mice. To investigate the mechanisms for this inhibition, Cr(VI) effects on basal and arsenic (As(III))-induced HO-1 expression were examined in cultured human bronchial epithelial (BEAS-2B) cells. An effect of Cr(VI) on the low basal HO-1 mRNA and protein levels in BEAS-2B cells was not detectible. In contrast, Cr(VI) added to the cells before As(III), but not simultaneously with As(III), attenuated As(III)-induced HO-1 expression. Transient transfection with luciferase reporter gene constructs controlled by the full length ho-1 promoter or deletion mutants demonstrated that this inhibition occurred in the E1 enhancer region containing critical antioxidant response elements (ARE). Cr(VI) pretreatment inhibited As(III)-induced activity of a transiently expressed reporter construct regulated by three ARE tandem repeats. The mechanism for this Cr(VI)-attenuated transactivation appeared to be Cr(VI) reduction of the nuclear levels of the transcription factor Nrf2 and As(III)-stimulated Nrf2 transcriptional complex binding to the ARE cis element. Finally, exposing cells to Cr(VI) prior to co-exposure with As(III) synergized for apoptosis and loss of membrane integrity. These data suggest that Cr(VI) silences induction of ARE-driven genes required for protection from secondary insults. The data also have important implications for understanding the toxic mechanisms of low level, mixed metal exposures in the lung."
627745,Bower et al. 2005,Conference overview: Molecular mechanisms of metal toxicity and carcinogenesis,"Chronic exposure to many heavy metals and metal-derivatives is associated with an increased risk of cancer, although the mechanisms of tumorigenesis are largely unknown. Approximately 125 scientists attended the 3rd Conference on Molecular Mechanisms of Metal Toxicity and Carcinogenesis and presented the latest research concerning these mechanisms. Major areas of focus included exposure assessment and biomarker identification, roles of ROS and antioxidants in carcinogenesis, mechanisms of metal-induced DNA damage, metal signalling, and the development of animal models for use in metal toxicology studies. Here we highlight some of the research presented, and summarize the conference proceedings.","Conference overview: Molecular mechanisms of metal toxicity and carcinogenesis Abs: Chronic exposure to many heavy metals and metal-derivatives is associated with an increased risk of cancer, although the mechanisms of tumorigenesis are largely unknown. Approximately 125 scientists attended the 3rd Conference on Molecular Mechanisms of Metal Toxicity and Carcinogenesis and presented the latest research concerning these mechanisms. Major areas of focus included exposure assessment and biomarker identification, roles of ROS and antioxidants in carcinogenesis, mechanisms of metal-induced DNA damage, metal signalling, and the development of animal models for use in metal toxicology studies. Here we highlight some of the research presented, and summarize the conference proceedings."
627477,Luster et al. 1995,Role of keratinocyte-derived cytokines in chemical toxicity,"Following appropriate stimulation, such as with tumor promoters, ultraviolet light or various chemical agents, keratinocytes synthesize and secrete cytokines which can mediate or participate in dermatotoxic responses such as inflammation, hyperkeratosis, hypersensitivity and skin cancer. We have determined the qualitative and quantitative cytokine response in primary human keratinocyte cultures following exposure to several non-sensitizing contact irritants, sensitizers and ulcerative agents as well as a skin carcinogen. The chemicals were also administered to mice to assess whether the dermatotoxic response correlated with the in vitro production of keratinocyte-derived cytokines. Due to the complex cellular interactions that occur in the skin, it was not possible to identify specific cytokine profiles for most of the classes of dermatotoxic agents studied. However, the non-sensitizing contact irritants produced relative increases in the synthesis and secretion of the proinflammatory cytokines, interleukin-1 and tumor necrosis factor-alpha, as well as the neutrophil chemotactic cytokine, interleukin-8 compared to the other chemical agents. While ulcerative compounds as well as irritants elicited neutrophils to the site of chemical application when applied to the mouse skin, time-dependent and chemical-specific patterns of inflammation were detected. Treatment of human keratinocyte cultures with arsenic, a human skin carcinogen, resulted in a unique cytokine profile characterized by induction of growth factors, including transforming growth factor-alpha and granulocyte-macrophage colony stimulating factor. Treatment of v-Ha-ras transgenic mice, an animal model for skin cancer, with arsenic caused an increase in the number of papillomas as well as overexpression of these growth factors suggesting that they participate in arsenic-induced skin papilloma development. These studies indicate a diverse role exists for keratinocyte-derived cytokines in dermatotoxic actions.","Role of keratinocyte-derived cytokines in chemical toxicity Abs: Following appropriate stimulation, such as with tumor promoters, ultraviolet light or various chemical agents, keratinocytes synthesize and secrete cytokines which can mediate or participate in dermatotoxic responses such as inflammation, hyperkeratosis, hypersensitivity and skin cancer. We have determined the qualitative and quantitative cytokine response in primary human keratinocyte cultures following exposure to several non-sensitizing contact irritants, sensitizers and ulcerative agents as well as a skin carcinogen. The chemicals were also administered to mice to assess whether the dermatotoxic response correlated with the in vitro production of keratinocyte-derived cytokines. Due to the complex cellular interactions that occur in the skin, it was not possible to identify specific cytokine profiles for most of the classes of dermatotoxic agents studied. However, the non-sensitizing contact irritants produced relative increases in the synthesis and secretion of the proinflammatory cytokines, interleukin-1 and tumor necrosis factor-alpha, as well as the neutrophil chemotactic cytokine, interleukin-8 compared to the other chemical agents. While ulcerative compounds as well as irritants elicited neutrophils to the site of chemical application when applied to the mouse skin, time-dependent and chemical-specific patterns of inflammation were detected. Treatment of human keratinocyte cultures with arsenic, a human skin carcinogen, resulted in a unique cytokine profile characterized by induction of growth factors, including transforming growth factor-alpha and granulocyte-macrophage colony stimulating factor. Treatment of v-Ha-ras transgenic mice, an animal model for skin cancer, with arsenic caused an increase in the number of papillomas as well as overexpression of these growth factors suggesting that they participate in arsenic-induced skin papilloma development. These studies indicate a diverse role exists for keratinocyte-derived cytokines in dermatotoxic actions."
627451,Andrew et al. 2003,Genomic and proteomic profiling of responses to toxic metals in human lung cells,"Examining global effects of toxic metals on gene expression can be useful for elucidating patterns of biological response, discovering underlying mechanisms of toxicity, and identifying candidate metal-specific genetic markers of exposure and response. Using a 1,200 gene nylon array, we examined changes in gene expression following low-dose, acute exposures of cadmium, chromium, arsenic, nickel, or mitomycin C (MMC) in BEAS-2B human bronchial epithelial cells. Total RNA was isolated from cells exposed to 3 M Cd(II) (as cadmium chloride), 10 M Cr(VI) (as sodium dichromate), 3 g/cm2 Ni(II) (as nickel subsulfide), 5 M or 50 M As(III) (as sodium arsenite), or 1 M MMC for 4 hr. Expression changes were verified at the protein level for several genes. Only a small subset of genes was differentially expressed in response to each agent: Cd, Cr, Ni, As (5 M), As (50 M), and MMC each differentially altered the expression of 25, 44, 31, 110, 65, and 16 individual genes, respectively. Few genes were commonly expressed among the various treatments. Only one gene was altered in response to all four metals (hsp90), and no gene overlapped among all five treatments. We also compared low-dose (5 M, noncytotoxic) and high-dose (50 M, cytotoxic) arsenic treatments, which surprisingly, affected expression of almost completely nonoverlapping subsets of genes, suggesting a threshold switch from a survival-based biological response at low doses to a death response at high doses.","Genomic and proteomic profiling of responses to toxic metals in human lung cells Abs: Examining global effects of toxic metals on gene expression can be useful for elucidating patterns of biological response, discovering underlying mechanisms of toxicity, and identifying candidate metal-specific genetic markers of exposure and response. Using a 1,200 gene nylon array, we examined changes in gene expression following low-dose, acute exposures of cadmium, chromium, arsenic, nickel, or mitomycin C (MMC) in BEAS-2B human bronchial epithelial cells. Total RNA was isolated from cells exposed to 3 M Cd(II) (as cadmium chloride), 10 M Cr(VI) (as sodium dichromate), 3 g/cm2 Ni(II) (as nickel subsulfide), 5 M or 50 M As(III) (as sodium arsenite), or 1 M MMC for 4 hr. Expression changes were verified at the protein level for several genes. Only a small subset of genes was differentially expressed in response to each agent: Cd, Cr, Ni, As (5 M), As (50 M), and MMC each differentially altered the expression of 25, 44, 31, 110, 65, and 16 individual genes, respectively. Few genes were commonly expressed among the various treatments. Only one gene was altered in response to all four metals (hsp90), and no gene overlapped among all five treatments. We also compared low-dose (5 M, noncytotoxic) and high-dose (50 M, cytotoxic) arsenic treatments, which surprisingly, affected expression of almost completely nonoverlapping subsets of genes, suggesting a threshold switch from a survival-based biological response at low doses to a death response at high doses."
626915,Maier et al. 2000,"Disruption of dioxin-inducible phase I and phase II gene expression patterns by cadmium, chromium, and arsenic","Recent work suggesting that cellular oxidative stress exerts an inhibitory effect on aromatic hydrocarbon receptor (AHR)-dependent gene expression led us to test the hypothesis that pro-oxidant environmental pollutants might alter the induction of detoxification genes by 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD), an AHR ligand. We found that, in mouse hepatoma Hepa-1 cells, TCDD-inducible cytochrome P450, Cyp1a1, and nicotinamide adenine dinucleotide phosphate-quinone oxidoreductase (Nqo1) mRNA accumulation were differentially affected by cadmium (Cd2+), chromium (Cr6+), and arsenic (As3+). Cadmium or arsenic did not change Cyp1a1 mRNA levels but did enhance TCDD-inducible levels of Nqo1 mRNA, an effect that paralleled the ability of these metals to activate a -galactosidase gene reporter system regulated by an electrophile response promoter element. Chromium inhibited mRNA accumulation for both Cyp1a1 and Nqo1. Manipulation of cellular thiol status did not modify the response to combined chromium-TCDD exposure, suggesting that the response was not caused by oxidative stress. Chromium did not block DNA-binding competence of the AHR and did not have an effect on mRNA stability, but it inhibited Cyp1a1 gene transcription and the expression of an AHR-dependent luciferase reporter. These data indicate that coexposure to pro-oxidant metals and AHR ligands, which is common in the environment, can disrupt the regulation of phase I and phase II detoxification genes, leading to imbalances in gene expression that may have important consequences for the toxicity of complex mixtures. Mol. Carcinog. 28:225-235, 2000. © 2000 Wiley-Liss, Inc.","Disruption of dioxin-inducible phase I and phase II gene expression patterns by cadmium, chromium, and arsenic Abs: Recent work suggesting that cellular oxidative stress exerts an inhibitory effect on aromatic hydrocarbon receptor (AHR)-dependent gene expression led us to test the hypothesis that pro-oxidant environmental pollutants might alter the induction of detoxification genes by 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD), an AHR ligand. We found that, in mouse hepatoma Hepa-1 cells, TCDD-inducible cytochrome P450, Cyp1a1, and nicotinamide adenine dinucleotide phosphate-quinone oxidoreductase (Nqo1) mRNA accumulation were differentially affected by cadmium (Cd2+), chromium (Cr6+), and arsenic (As3+). Cadmium or arsenic did not change Cyp1a1 mRNA levels but did enhance TCDD-inducible levels of Nqo1 mRNA, an effect that paralleled the ability of these metals to activate a -galactosidase gene reporter system regulated by an electrophile response promoter element. Chromium inhibited mRNA accumulation for both Cyp1a1 and Nqo1. Manipulation of cellular thiol status did not modify the response to combined chromium-TCDD exposure, suggesting that the response was not caused by oxidative stress. Chromium did not block DNA-binding competence of the AHR and did not have an effect on mRNA stability, but it inhibited Cyp1a1 gene transcription and the expression of an AHR-dependent luciferase reporter. These data indicate that coexposure to pro-oxidant metals and AHR ligands, which is common in the environment, can disrupt the regulation of phase I and phase II detoxification genes, leading to imbalances in gene expression that may have important consequences for the toxicity of complex mixtures. Mol. Carcinog. 28:225-235, 2000. © 2000 Wiley-Liss, Inc."
626735,Luce et al. 1993,Sinonasal cancer and occupational exposure to formaldehyde and other substances,"A case-control study of cancer of the nose and paranasal sinuses was conducted in France to determine whether occupational exposure to formaldehyde was associated with an Increased risk of sinonasal cancer. Exposures to 14 other substances or groups of substances were also studied (wood dust, leather dust, textile dust, flour dust, sugar dust, coal/coke dust, nickel compounds, chromium compounds, chromium VI, welding fumes, soldering fumes, cutting oils, paints and lacquers, glues and adhesives). Cases (n = 207) and controls (n = 409) were interviewed to obtain detailed information on job history and other potential risk factors for sinonasal cancer. In addition, a questionnaire specially designed for this study was used to help assess exposures to formaldehyde and other substances of interest. The questionnaires were translated into history of occupational exposure by an expert in industrial hygiene, without knowledge of case-control status. Several exposure variables (lifetime average level, duration, cumulative level) were used to describe the risks related to exposure to formaldehyde. Potential confounding factors (occupational and non occupational) were examined and adjusted for when necessary. No significant association was found between exposure to formaldehyde and squamous-cell carcinomas of the sinonasal cavities. Because of the strong association between exposure to wood dust and nasal adenocarcinoma, it was not possible to assess an independent effect of formaldehyde on this type of cancer. However, among males exposed to medium or high levels of wood dust, the risk of adenocarcinoma associated with formaldehyde was significantly elevated for the highest exposure categories for average level (OR = 5.3, 95% confidence interval = 1.3-22.2), cumulative level (OR = 6.9, 95% CI = 1.7- 28.2) and duration of exposure (OR = 6.9,95% CI = 1.7-27.8). Although a residual confounding effect of wood dust could not be excluded, this study suggests that exposure to both formaldehyde and wood dust may increase the risk of nasal adenocarcinoma, by comparison with the risk due to wood dust alone. This study also indicated an increased risk among males who had been exposed to glues and adhesives, for all histologic types, which was not explained by a confounding effect of paints and lacquers, wood dust or formaldehyde. No other significant association was observed.","Sinonasal cancer and occupational exposure to formaldehyde and other substances Abs: A case-control study of cancer of the nose and paranasal sinuses was conducted in France to determine whether occupational exposure to formaldehyde was associated with an Increased risk of sinonasal cancer. Exposures to 14 other substances or groups of substances were also studied (wood dust, leather dust, textile dust, flour dust, sugar dust, coal/coke dust, nickel compounds, chromium compounds, chromium VI, welding fumes, soldering fumes, cutting oils, paints and lacquers, glues and adhesives). Cases (n = 207) and controls (n = 409) were interviewed to obtain detailed information on job history and other potential risk factors for sinonasal cancer. In addition, a questionnaire specially designed for this study was used to help assess exposures to formaldehyde and other substances of interest. The questionnaires were translated into history of occupational exposure by an expert in industrial hygiene, without knowledge of case-control status. Several exposure variables (lifetime average level, duration, cumulative level) were used to describe the risks related to exposure to formaldehyde. Potential confounding factors (occupational and non occupational) were examined and adjusted for when necessary. No significant association was found between exposure to formaldehyde and squamous-cell carcinomas of the sinonasal cavities. Because of the strong association between exposure to wood dust and nasal adenocarcinoma, it was not possible to assess an independent effect of formaldehyde on this type of cancer. However, among males exposed to medium or high levels of wood dust, the risk of adenocarcinoma associated with formaldehyde was significantly elevated for the highest exposure categories for average level (OR = 5.3, 95% confidence interval = 1.3-22.2), cumulative level (OR = 6.9, 95% CI = 1.7- 28.2) and duration of exposure (OR = 6.9,95% CI = 1.7-27.8). Although a residual confounding effect of wood dust could not be excluded, this study suggests that exposure to both formaldehyde and wood dust may increase the risk of nasal adenocarcinoma, by comparison with the risk due to wood dust alone. This study also indicated an increased risk among males who had been exposed to glues and adhesives, for all histologic types, which was not explained by a confounding effect of paints and lacquers, wood dust or formaldehyde. No other significant association was observed."
626459,Gustavsson et al. 1998,"Occupational exposures and squamous cell carcinoma of the oral cavity, pharynx, larynx, and oesophagus: A case-control study in Sweden","OBJECTIVES: This community based case-referent study was initiated to investigate aetiological factors for squamous cell carcinoma of the upper gastrointestinal tract. METHODS: The study was based on all Swedish men aged 40-79 living in two regions of Sweden during 1988-90. Within that base, efforts were made to identify all incident cases of squamous cell carcinoma of the oral cavity, oropharynx and hypopharynx, larynx, and oesophagus. Referents were selected as a stratified (age, region) random sample of the base. The response was 90% among cases and 85% among referents. There were 545 cases and 641 referents in the final study group. The study subjects were interviewed about several lifestyle factors and a life history of occupations and work tasks. The exposure to 17 specific agents were coded by an occupational hygienist. The relative risk (RR) of cancer was calculated by logistic regression, standardising for age, geographical region, and alcohol and tobacco consumption. RESULTS: Exposure to asbestos was associated with an increased risk of laryngeal cancer, and a dose-response relation was present. The RR was 1.8 (95% confidence interval (95% CI) 1.1 to 3.0) in the highest exposure group. More than eight years of exposure to welding fumes was associated with an increased risk of pharyngeal cancer (RR 2.3 (1.1 to 4.7)), and laryngeal cancer (RR 2.0 (1.0 to 3.7)). There were indications of a dose-response for duration of exposure. Associations were also found for high exposure to polycyclic aromatic hydrocarbons (PAHs) and oesophageal cancer, RR 1.9 (1.1 to 3.2). Exposure to wood dust was associated with a decreased risk of cancer at the studied sites. CONCLUSIONS: Some of the present findings confirm known or suspected associations--such as asbestos and laryngeal cancer. The study indicates that welding may cause an increased risk of pharyngeal as well as laryngeal cancer. The findings corroborate an association between exposure to PAHs and oesophageal cancer.","Occupational exposures and squamous cell carcinoma of the oral cavity, pharynx, larynx, and oesophagus: A case-control study in Sweden Abs: OBJECTIVES: This community based case-referent study was initiated to investigate aetiological factors for squamous cell carcinoma of the upper gastrointestinal tract. METHODS: The study was based on all Swedish men aged 40-79 living in two regions of Sweden during 1988-90. Within that base, efforts were made to identify all incident cases of squamous cell carcinoma of the oral cavity, oropharynx and hypopharynx, larynx, and oesophagus. Referents were selected as a stratified (age, region) random sample of the base. The response was 90% among cases and 85% among referents. There were 545 cases and 641 referents in the final study group. The study subjects were interviewed about several lifestyle factors and a life history of occupations and work tasks. The exposure to 17 specific agents were coded by an occupational hygienist. The relative risk (RR) of cancer was calculated by logistic regression, standardising for age, geographical region, and alcohol and tobacco consumption. RESULTS: Exposure to asbestos was associated with an increased risk of laryngeal cancer, and a dose-response relation was present. The RR was 1.8 (95% confidence interval (95% CI) 1.1 to 3.0) in the highest exposure group. More than eight years of exposure to welding fumes was associated with an increased risk of pharyngeal cancer (RR 2.3 (1.1 to 4.7)), and laryngeal cancer (RR 2.0 (1.0 to 3.7)). There were indications of a dose-response for duration of exposure. Associations were also found for high exposure to polycyclic aromatic hydrocarbons (PAHs) and oesophageal cancer, RR 1.9 (1.1 to 3.2). Exposure to wood dust was associated with a decreased risk of cancer at the studied sites. CONCLUSIONS: Some of the present findings confirm known or suspected associations--such as asbestos and laryngeal cancer. The study indicates that welding may cause an increased risk of pharyngeal as well as laryngeal cancer. The findings corroborate an association between exposure to PAHs and oesophageal cancer."
626336,Fornace 1982,Detection of DNA single-strand breaks produced during the repair of damage by DNA-protein cross-linking agents,"In this investigation, the combination of 1-beta-D-arabinofuranosylcytosine and hydroxyurea was used to inhibit the polymerase step of DNA excision repair. The DNA single-strand breaks (SSB), which accumulated in the presence of these agents, were measured by alkaline elution. With this approach, DNA SSB were detected in normal human fibroblasts after exposure to trans-platinum(II)diamminedichloride, formaldehyde, or potassium chromate. These agents all share the common feature that they induce DNA-protein cross-links in mammalian cells. In the case of trans-platinum(II)diamminedichloride or formaldehyde, the frequency of these SSB was markedly less in excision-deficient xeroderma pigmentosum cells. With chromate, a high level of SSB was induced in both normal and xeroderma pigmentosum cells; these results indicate that chromate damage to DNA is repaired by a mechanism different than the classical excision pathway since xeroderma pigmentosum cells responded normally. Several other agents were investigated with this approach, and no SSB were detected with nickel sulfate, 12-O-tetradecanoylphorbol-13-acetate or asbestos fibers in the presence of the polymerase inhibitor. This approach was found to be a very sensitive method to detect DNA excision repair.","Detection of DNA single-strand breaks produced during the repair of damage by DNA-protein cross-linking agents Abs: In this investigation, the combination of 1-beta-D-arabinofuranosylcytosine and hydroxyurea was used to inhibit the polymerase step of DNA excision repair. The DNA single-strand breaks (SSB), which accumulated in the presence of these agents, were measured by alkaline elution. With this approach, DNA SSB were detected in normal human fibroblasts after exposure to trans-platinum(II)diamminedichloride, formaldehyde, or potassium chromate. These agents all share the common feature that they induce DNA-protein cross-links in mammalian cells. In the case of trans-platinum(II)diamminedichloride or formaldehyde, the frequency of these SSB was markedly less in excision-deficient xeroderma pigmentosum cells. With chromate, a high level of SSB was induced in both normal and xeroderma pigmentosum cells; these results indicate that chromate damage to DNA is repaired by a mechanism different than the classical excision pathway since xeroderma pigmentosum cells responded normally. Several other agents were investigated with this approach, and no SSB were detected with nickel sulfate, 12-O-tetradecanoylphorbol-13-acetate or asbestos fibers in the presence of the polymerase inhibitor. This approach was found to be a very sensitive method to detect DNA excision repair."
626094,Hald et al. 2009,Allergens associated with severe symptoms of hand eczema and a poor prognosis,"BACKGROUND: Contact allergy is frequent among persons with hand eczema and may be associated with a poor prognosis. OBJECTIVES: To identify allergens associated with the most severe initial clinical symptoms and the worst prognosis in a cohort of hand eczema patients followed for 6 months. METHODS: The study population comprised 799 consecutive hand eczema patients enrolled during January 2006-February 2007. All patients were patch tested with the European baseline series. Severity assessment of the hand eczema was performed initially and at the 6-month follow-up using a validated scoring system (HECSI). With logistic regression analyses, associations of severe hand eczema or a poor prognosis with 15 individual allergens were analysed and adjusted for by sex, age, atopic dermatitis and other allergens. RESULTS: At baseline, greater severity of hand eczema was associated with a positive patch test to formaldehyde, methyldibromo glutaronitrile, sesquiterpene lactone mix, nickel sulfate and potassium dichromate. A poor prognosis was associated with chromate allergy, odds ratio: 4.18 (95% CI: 1.42-12.28). CONCLUSIONS: Nickel, chromate, formaldehyde, methyldibromo glutaronitrile and sesquiterpene lactone mix were allergens associated with the greatest severity of hand eczema. Patients with chromate allergy had the worst prognosis.","Allergens associated with severe symptoms of hand eczema and a poor prognosis Abs: BACKGROUND: Contact allergy is frequent among persons with hand eczema and may be associated with a poor prognosis. OBJECTIVES: To identify allergens associated with the most severe initial clinical symptoms and the worst prognosis in a cohort of hand eczema patients followed for 6 months. METHODS: The study population comprised 799 consecutive hand eczema patients enrolled during January 2006-February 2007. All patients were patch tested with the European baseline series. Severity assessment of the hand eczema was performed initially and at the 6-month follow-up using a validated scoring system (HECSI). With logistic regression analyses, associations of severe hand eczema or a poor prognosis with 15 individual allergens were analysed and adjusted for by sex, age, atopic dermatitis and other allergens. RESULTS: At baseline, greater severity of hand eczema was associated with a positive patch test to formaldehyde, methyldibromo glutaronitrile, sesquiterpene lactone mix, nickel sulfate and potassium dichromate. A poor prognosis was associated with chromate allergy, odds ratio: 4.18 (95% CI: 1.42-12.28). CONCLUSIONS: Nickel, chromate, formaldehyde, methyldibromo glutaronitrile and sesquiterpene lactone mix were allergens associated with the greatest severity of hand eczema. Patients with chromate allergy had the worst prognosis."
626079,Le Curieux et al. 1993,Comparison of three short-term assays: Results on seven chemicals. Potential contribution to the control of water genotoxicity,"Three short-term assays (the SOS chromotest, the Ames fluctuation test and the newt micronucleus test) were used to evaluate the genotoxicity of seven chemicals (4-nitroquinoline 1-oxide, potassium dichromate, formaldehyde, sodium hypochlorite, benzo[a]pyrene, cyclophosphamide and 2-naphthylamine). In the SOS chromotest, all seven compounds except sodium hypochlorite and cyclophosphamide were found to induce primary DNA damage in E. coli. With the Ames fluctuation test, all seven chemicals except sodium hypochlorite showed mutagenic activity on Salmonella typhimurium TA100, TA102 or TA98. The newt micronucleus assay detected a clastogenic effect of all seven compounds except formaldehyde on the peripheral blood erythrocytes of Pleurodeles waltl larvae. For each compound, the sensitivity of the tests was compared; (1) the SOS chromotest is the least sensitive assay in every case, (2) the Ames fluctuation test is the most sensitive assay for studied chemicals with direct genotoxic effect and (3) the newt micronucleus assay is the most sensitive test for tested compounds with indirect genotoxic activity. The potential contribution of these three tests in the monitoring of water genotoxicity is discussed.","Comparison of three short-term assays: Results on seven chemicals. Potential contribution to the control of water genotoxicity Abs: Three short-term assays (the SOS chromotest, the Ames fluctuation test and the newt micronucleus test) were used to evaluate the genotoxicity of seven chemicals (4-nitroquinoline 1-oxide, potassium dichromate, formaldehyde, sodium hypochlorite, benzo[a]pyrene, cyclophosphamide and 2-naphthylamine). In the SOS chromotest, all seven compounds except sodium hypochlorite and cyclophosphamide were found to induce primary DNA damage in E. coli. With the Ames fluctuation test, all seven chemicals except sodium hypochlorite showed mutagenic activity on Salmonella typhimurium TA100, TA102 or TA98. The newt micronucleus assay detected a clastogenic effect of all seven compounds except formaldehyde on the peripheral blood erythrocytes of Pleurodeles waltl larvae. For each compound, the sensitivity of the tests was compared; (1) the SOS chromotest is the least sensitive assay in every case, (2) the Ames fluctuation test is the most sensitive assay for studied chemicals with direct genotoxic effect and (3) the newt micronucleus assay is the most sensitive test for tested compounds with indirect genotoxic activity. The potential contribution of these three tests in the monitoring of water genotoxicity is discussed."
626038,Garrett and  Lewtas 1983,Cellular toxicity in Chinese hamster ovary cell cultures: I. Analysis of cytotoxicity endpoints for twenty-nine priority pollutants,"Chinese hamster ovary cells were exposed to 29 toxic chemical substances which were representative of several classes of compounds listed by the Natural Resources Defense Council Consent Decree as priority toxic pollutants. After cell cultures were exposed to the test substance, cell samples were assayed for protein and DNA synthesis, ATP, cell number, and viability. A filter-disk technique employing a batch-washing procedure was used for the determination of protein and DNA synthesis. Dose-response data were obtained for 15 of the more toxic agents including chlorinated aromatics, metallic compounds, phenols, and polychlorinated biphenyls. Estimates of the sample concentrations necessary to produce a 50% reduction in response were used to compare cytotoxicity endpoints. ATP and protein synthesis were approximately equally effective as indicators of cellular toxicity. Cadmium chloride, nickel nitrate, arsenic trioxide, and potassium chromate produced a more pronounced effect on DNA synthesis than on ATP or protein synthesis. The dose-response relationship for protein and DNA synthesis was a smooth, continuous function for responses as low as 1 to 2% of the control. On a log-log scale, the dose-response relation yielded a unique pattern for several chemical classes. A ranking of the compounds based on their inhibition of DNA synthesis was compared to a ranking obtained from the literature for whole-animal toxicity. With the exception of the polychlorinated biphenyls, the in vitro results correlated well with animal test data.","Cellular toxicity in Chinese hamster ovary cell cultures: I. Analysis of cytotoxicity endpoints for twenty-nine priority pollutants Abs: Chinese hamster ovary cells were exposed to 29 toxic chemical substances which were representative of several classes of compounds listed by the Natural Resources Defense Council Consent Decree as priority toxic pollutants. After cell cultures were exposed to the test substance, cell samples were assayed for protein and DNA synthesis, ATP, cell number, and viability. A filter-disk technique employing a batch-washing procedure was used for the determination of protein and DNA synthesis. Dose-response data were obtained for 15 of the more toxic agents including chlorinated aromatics, metallic compounds, phenols, and polychlorinated biphenyls. Estimates of the sample concentrations necessary to produce a 50% reduction in response were used to compare cytotoxicity endpoints. ATP and protein synthesis were approximately equally effective as indicators of cellular toxicity. Cadmium chloride, nickel nitrate, arsenic trioxide, and potassium chromate produced a more pronounced effect on DNA synthesis than on ATP or protein synthesis. The dose-response relationship for protein and DNA synthesis was a smooth, continuous function for responses as low as 1 to 2% of the control. On a log-log scale, the dose-response relation yielded a unique pattern for several chemical classes. A ranking of the compounds based on their inhibition of DNA synthesis was compared to a ranking obtained from the literature for whole-animal toxicity. With the exception of the polychlorinated biphenyls, the in vitro results correlated well with animal test data."
625735,Chou et al. 1998,Minimal risk levels (MRLs) for hazardous substances,"The Comprehensive Environmental Response, Compensation, and Liability Act (CERCLA) (42 U.S.C 9604 et seq.), as amended by the Superfund Amendments and Reauthorization Act (SARA) (Pub. L. 99-499), requires that the Agency for Toxic Substances and Disease Registry (ATSDR) develop jointly with the U.S. Environmental Protection Agency (USEPA), in order of priority, a list of hazardous substances most commonly found at facilities on the CERCLA National Priorities List (NPL) (42 U.S.C 9604(i)(2)); prepare toxicological profiles for each substance included on the priority list of hazardous substances, and ascertain in the toxicological profiles, significant human exposure levels (SHELs) for hazardous substances in the environment, and the associated acute, subacute, and chronic health effects (42 U.S.C 9604(i)(3)); and assure the initiation of a research program to fill identified data needs associated with the substances (42 U.S.C. 9604(i)(5)). The ATSDR Minimal Risk Levels were developed as an initial response to the mandate and to provide screening levels for health assessors and other responders to identify contaminants and potential health effects that may be of concern at hazardous waste sites and releases. An MRL is an estimate of the daily human exposure to a hazardous substance that is likely to be without appreciable risk of adverse noncancer health effects over a specified duration of exposure. In this paper, we describe ATSDR's current approach for deriving MRLs for priority hazardous substances. The MRLs for a particular substance are published in the toxicological profile for that substance. A listing of the current published MRLs as of December 1997 is also provided.","Minimal risk levels (MRLs) for hazardous substances Abs: The Comprehensive Environmental Response, Compensation, and Liability Act (CERCLA) (42 U.S.C 9604 et seq.), as amended by the Superfund Amendments and Reauthorization Act (SARA) (Pub. L. 99-499), requires that the Agency for Toxic Substances and Disease Registry (ATSDR) develop jointly with the U.S. Environmental Protection Agency (USEPA), in order of priority, a list of hazardous substances most commonly found at facilities on the CERCLA National Priorities List (NPL) (42 U.S.C 9604(i)(2)); prepare toxicological profiles for each substance included on the priority list of hazardous substances, and ascertain in the toxicological profiles, significant human exposure levels (SHELs) for hazardous substances in the environment, and the associated acute, subacute, and chronic health effects (42 U.S.C 9604(i)(3)); and assure the initiation of a research program to fill identified data needs associated with the substances (42 U.S.C. 9604(i)(5)). The ATSDR Minimal Risk Levels were developed as an initial response to the mandate and to provide screening levels for health assessors and other responders to identify contaminants and potential health effects that may be of concern at hazardous waste sites and releases. An MRL is an estimate of the daily human exposure to a hazardous substance that is likely to be without appreciable risk of adverse noncancer health effects over a specified duration of exposure. In this paper, we describe ATSDR's current approach for deriving MRLs for priority hazardous substances. The MRLs for a particular substance are published in the toxicological profile for that substance. A listing of the current published MRLs as of December 1997 is also provided."
625621,Wise et al. 2010,Silver nanospheres are cytotoxic and genotoxic to fish cells,"Nanoparticles are being widely investigated for a range of applications due to their unique physical properties. For example, silver nanoparticles are used in commercial products for their antibacterial and antifungal properties. Some of these products are likely to result in silver nanoparticles reaching the aquatic environment. As such, nanoparticles pose a health concern for humans and aquatic species. We used a medaka (Oryzias latipes) cell line to investigate the cytotoxicity and genotoxicity of 30nm diameter silver nanospheres. Treatments of 0.05, 0.3, 0.5, 3 and 5microg/cm(2) induced 80, 45.7, 24.3, 1 and 0.1% survival, respectively, in a colony forming assay. Silver nanoparticles also induced chromosomal aberrations and aneuploidy. Treatments of 0, 0.05, 0.1 and 0.3microg/cm(2) induced damage in 8, 10.8, 16 and 15.8% of metaphases and 10.8, 15.6, 24 and 24 total aberrations in 100 metaphases, respectively. These data show that silver nanoparticles are cytotoxic and genotoxic to fish cells.","Silver nanospheres are cytotoxic and genotoxic to fish cells Abs: Nanoparticles are being widely investigated for a range of applications due to their unique physical properties. For example, silver nanoparticles are used in commercial products for their antibacterial and antifungal properties. Some of these products are likely to result in silver nanoparticles reaching the aquatic environment. As such, nanoparticles pose a health concern for humans and aquatic species. We used a medaka (Oryzias latipes) cell line to investigate the cytotoxicity and genotoxicity of 30nm diameter silver nanospheres. Treatments of 0.05, 0.3, 0.5, 3 and 5microg/cm(2) induced 80, 45.7, 24.3, 1 and 0.1% survival, respectively, in a colony forming assay. Silver nanoparticles also induced chromosomal aberrations and aneuploidy. Treatments of 0, 0.05, 0.1 and 0.3microg/cm(2) induced damage in 8, 10.8, 16 and 15.8% of metaphases and 10.8, 15.6, 24 and 24 total aberrations in 100 metaphases, respectively. These data show that silver nanoparticles are cytotoxic and genotoxic to fish cells."
616757,Pournourmohammadi et al. 2008,Study on the oxidative stress status among cement plant workers,"The cement industry is considered as a major pollution problem because of dust and particulate matter emitted at various steps of cement production. In the present study, volunteer male workers from a cement factory were studied for oxidative and nitrosative stress biomarkers in relation to their serum levels of aluminum (Al) and chromium (Cr). The subjects were divided into two groups of direct and indirect exposure. Subject who worked in production steps were considered as direct exposure group, and those who worked in administration building were considered as indirect exposure group. For comparison, healthy subjects at the same age and socio-economic status were tested as a control group. Serum levels of lipid peroxidation (LP), total antioxidant capacity (TAC), total thiol molecules (TTM), and nitric oxide (NO) as well as Al and Cr were measured. The results indicated a significant increase in Al (P = 0.001) and Cr (P = 0.009) levels in direct-exposed workers in comparison to healthy control group. Further, a significant increase in Al (P = 0.002) and Cr (P = 0.009) levels was observed in direct-exposed workers as compared to indirect-exposed one. Serum levels of TTM and TAC were significantly lower in both direct-and indirect- exposed groups in comparison to healthy control group (P = 0.00). Serum TTM and TAC were significantly lower in direct-exposed workers as compared to indirect-exposed ones (P = 0.00 and P = 0.024, respectively). There was no significant difference on the level of LP and NO among groups. A correlation was found between serum level of Cr, TAC, and platelets between direct-and indirect-exposed groups (P < 0.05). Further correlation was found among serum level of Cr and those of TTM, platelets, and chronic disease (P < 0.05). Chronic disease had a significant influence adjusted to other predictor variables on the post-shift values of Al (P < 0.05). Although plasma levels of Al and Cr were found in normal ranges,... [ABSTRACT FROM AUTHOR] Copyright of Human & Experimental Toxicology is the property of Sage Publications, Ltd. and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts)","Study on the oxidative stress status among cement plant workers Abs: The cement industry is considered as a major pollution problem because of dust and particulate matter emitted at various steps of cement production. In the present study, volunteer male workers from a cement factory were studied for oxidative and nitrosative stress biomarkers in relation to their serum levels of aluminum (Al) and chromium (Cr). The subjects were divided into two groups of direct and indirect exposure. Subject who worked in production steps were considered as direct exposure group, and those who worked in administration building were considered as indirect exposure group. For comparison, healthy subjects at the same age and socio-economic status were tested as a control group. Serum levels of lipid peroxidation (LP), total antioxidant capacity (TAC), total thiol molecules (TTM), and nitric oxide (NO) as well as Al and Cr were measured. The results indicated a significant increase in Al (P = 0.001) and Cr (P = 0.009) levels in direct-exposed workers in comparison to healthy control group. Further, a significant increase in Al (P = 0.002) and Cr (P = 0.009) levels was observed in direct-exposed workers as compared to indirect-exposed one. Serum levels of TTM and TAC were significantly lower in both direct-and indirect- exposed groups in comparison to healthy control group (P = 0.00). Serum TTM and TAC were significantly lower in direct-exposed workers as compared to indirect-exposed ones (P = 0.00 and P = 0.024, respectively). There was no significant difference on the level of LP and NO among groups. A correlation was found between serum level of Cr, TAC, and platelets between direct-and indirect-exposed groups (P < 0.05). Further correlation was found among serum level of Cr and those of TTM, platelets, and chronic disease (P < 0.05). Chronic disease had a significant influence adjusted to other predictor variables on the post-shift values of Al (P < 0.05). Although plasma levels of Al and Cr were found in normal ranges,... [ABSTRACT FROM AUTHOR] Copyright of Human & Experimental Toxicology is the property of Sage Publications, Ltd. and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts)"
616497,Pierre et al. 2008,Biomonitoring of two types of chromium exposure in an electroplating shop,"This study is concerned with two specific chromium (Cr) exposure situations at a hard-process electroplating company. Its aims are to define variations in urinary Cr concentration and to clarify their exposure relationships. Airborne chromium exposure and urinary excretion were measured for a-one week period. The majority of the exposed population was divided into two groups distinguishing chromium plating and polishing functions. Analysis of airborne Cr distinguished water soluble Cr(VI), water total soluble Cr and water insoluble Cr. Volunteers provided 6Ã¢â‚¬â€œ7 urine samples per day for a monitoring period of 7 days. Differences between the two groups appear in relation to the type of exposure. Low concentration water soluble Cr(VI) (5.3 ÃŽÂ¼g/m<sup>3</sup> maximum) in electroplating shops is practically undetected in other workshops. Water insoluble Cr present in low concentration in electroplating exceeds 1 mg/m<sup>3</sup> in polishing shops. Total soluble Cr concentrations are similar in these two activities (3Ã¢Ë†â€™10 ÃŽÂ¼g/m<sup>3</sup>). In polishing, 0.4% of the Cr aerosol comprises soluble Cr. Urinary Cr varied according to a 24 h cycle in similar manner in both groups throughout the monitoring week. Minimum values (3Ã¢â‚¬â€œ10 ÃŽÂ¼g/g crea) occurred when starting a work shift, following by a rapid rise as soon as exposure commenced, whilst maximum values (12Ã¢â‚¬â€œ30 ÃŽÂ¼g/g crea) were recorded towards the end of the work shift. Although uncorrelated with soluble Cr(VI), urinary Cr (24 h) is effectively related to the soluble fraction of airborne chromium. In the case of chromium electroplating, correspondence between exposure and excretion appears to be governed by relationships different to those emerging from stainless steel welding, from which current biological limit values have been derived. ABSTRACT FROM AUTHOR Copyright of International Archives of Occupational & Environmental Health is the property of Springer Science & Business Media B.V. and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts)","Biomonitoring of two types of chromium exposure in an electroplating shop Abs: This study is concerned with two specific chromium (Cr) exposure situations at a hard-process electroplating company. Its aims are to define variations in urinary Cr concentration and to clarify their exposure relationships. Airborne chromium exposure and urinary excretion were measured for a-one week period. The majority of the exposed population was divided into two groups distinguishing chromium plating and polishing functions. Analysis of airborne Cr distinguished water soluble Cr(VI), water total soluble Cr and water insoluble Cr. Volunteers provided 6Ã¢â‚¬â€œ7 urine samples per day for a monitoring period of 7 days. Differences between the two groups appear in relation to the type of exposure. Low concentration water soluble Cr(VI) (5.3 ÃŽÂ¼g/m<sup>3</sup> maximum) in electroplating shops is practically undetected in other workshops. Water insoluble Cr present in low concentration in electroplating exceeds 1 mg/m<sup>3</sup> in polishing shops. Total soluble Cr concentrations are similar in these two activities (3Ã¢Ë†â€™10 ÃŽÂ¼g/m<sup>3</sup>). In polishing, 0.4% of the Cr aerosol comprises soluble Cr. Urinary Cr varied according to a 24 h cycle in similar manner in both groups throughout the monitoring week. Minimum values (3Ã¢â‚¬â€œ10 ÃŽÂ¼g/g crea) occurred when starting a work shift, following by a rapid rise as soon as exposure commenced, whilst maximum values (12Ã¢â‚¬â€œ30 ÃŽÂ¼g/g crea) were recorded towards the end of the work shift. Although uncorrelated with soluble Cr(VI), urinary Cr (24 h) is effectively related to the soluble fraction of airborne chromium. In the case of chromium electroplating, correspondence between exposure and excretion appears to be governed by relationships different to those emerging from stainless steel welding, from which current biological limit values have been derived. ABSTRACT FROM AUTHOR Copyright of International Archives of Occupational & Environmental Health is the property of Springer Science & Business Media B.V. and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts)"
616139,Patlolla et al. 2009,"Oxidative Stress, DNA Damage, and Antioxidant Enzyme Activity Induced by Hexavalent Chromium in Sprague-Dawley Rats","Chromium is a widespread industrial compound. The soluble hexavalent chromium Cr (VI) is an environmental contaminant widely recognized as carcinogen, mutagen, and teratogen toward humans and animals. The fate of chromium in the environment is dependent on its oxidation state. The reduction of Cr (VI) to Cr (III) results in the formation of reactive intermediates leading to oxidative tissue damage and cellular injury. In the present investigation, Potassium dichromate was given intraperitoneally to Sprague-Dawley rats for 5 days with the doses of 2.5, 5.0, 7.5, and 10 mg/kg body weight per day. Oxidative stress including the level of reactive oxygen species (ROS), the extent of lipid peroxidation and the activity of antioxidant enzymes in both liver and kidney was determined. DNA damage in peripheral blood lymphocytes was determined by single-cell gel electrophoresis (comet assay). The results indicated that administration of Cr (VI) had caused a significant increase of ROS level in both liver and kidney after 5 days of exposure, accompanied with a dose-dependent increase in superoxide dismutase and catalase activities. The malondialdehyde content in liver and kidney was elevated as compared with the control animals. Dose- and time-dependent effects were observed on DNA damage after 24, 48, 72, and 96 h posttreatment. The results obtained from the present study showed that Cr (VI) could induce dose- and time-dependent effects on DNA damage, both liver and kidney show defense against chromium-induced oxidative stress by enhancing their antioxidant enzyme activity. However, liver was found to exhibit more antioxidant defense than the kidney. (C) 2008 Wiley Periodicals, Inc. Environ Toxicol 24: 66-73, 2009.","Oxidative Stress, DNA Damage, and Antioxidant Enzyme Activity Induced by Hexavalent Chromium in Sprague-Dawley Rats Abs: Chromium is a widespread industrial compound. The soluble hexavalent chromium Cr (VI) is an environmental contaminant widely recognized as carcinogen, mutagen, and teratogen toward humans and animals. The fate of chromium in the environment is dependent on its oxidation state. The reduction of Cr (VI) to Cr (III) results in the formation of reactive intermediates leading to oxidative tissue damage and cellular injury. In the present investigation, Potassium dichromate was given intraperitoneally to Sprague-Dawley rats for 5 days with the doses of 2.5, 5.0, 7.5, and 10 mg/kg body weight per day. Oxidative stress including the level of reactive oxygen species (ROS), the extent of lipid peroxidation and the activity of antioxidant enzymes in both liver and kidney was determined. DNA damage in peripheral blood lymphocytes was determined by single-cell gel electrophoresis (comet assay). The results indicated that administration of Cr (VI) had caused a significant increase of ROS level in both liver and kidney after 5 days of exposure, accompanied with a dose-dependent increase in superoxide dismutase and catalase activities. The malondialdehyde content in liver and kidney was elevated as compared with the control animals. Dose- and time-dependent effects were observed on DNA damage after 24, 48, 72, and 96 h posttreatment. The results obtained from the present study showed that Cr (VI) could induce dose- and time-dependent effects on DNA damage, both liver and kidney show defense against chromium-induced oxidative stress by enhancing their antioxidant enzyme activity. However, liver was found to exhibit more antioxidant defense than the kidney. (C) 2008 Wiley Periodicals, Inc. Environ Toxicol 24: 66-73, 2009."
615850,Pandey and  Upadhyay 2005,Effect of micellar aggregates on the kinetics of oxidation of ?-aminoacids by chloramine-T in perchloric acid medium,"The kinetics of oxidation of some @a-aminoacids viz. alanine, phenylalanine and valine by chloramine-T in HClO""4 medium have been investigated in absence and in presence of three types of surfactants, viz. an anionic (sodium lauryl...","Effect of micellar aggregates on the kinetics of oxidation of ?-aminoacids by chloramine-T in perchloric acid medium Abs: The kinetics of oxidation of some @a-aminoacids viz. alanine, phenylalanine and valine by chloramine-T in HClO""4 medium have been investigated in absence and in presence of three types of surfactants, viz. an anionic (sodium lauryl..."
615096,Nieto Castillo et al. 2008,Changes in chromium distribution during the electrodialytic remediation of a Cr (VI)-contaminated soil,"A laboratory study has been carried out to determine the feasibility of in situ remediation of chromium (VI)-contaminated soil using electrodialysis in relation to its speciation in soil. This technique is best suited for low-permeability soils or sediments, which may be difficult to remediate by other means and implies the application of a low-intensity direct current to the soil, which is separated from the electrode compartments by ion-exchange membranes. A clayey soil was prepared for use in the experiments and was characterized before being mixed with a solution of potassium dichromate for several days to produce a final Cr content of 4,056 mg/kg of soil dry wt. Remediation tests were carried out under constant-voltage conditions for periods of 7Ã¢â‚¬â€œ14 days and the evolution of applied current to the cell, pH, and conductivity of the electrolytes were recorded periodically. Fractionation of chromium was determined for soil samples before and after remediation using a standardized four-step sequential extraction procedure (SEP) with acetic acid, hydroxylamine, hydrogen peroxide, and aqua regia solutions. Results show that chromium is mobilized from the most labile phases (soluble/exchangeable/carbonate). In a 15 V test, SEP results show that the amount of chromium extracted in the first step drops from 80% to 9%, but also that changes in the total chromium distribution occur during the treatment with some transferred to other soil phases that are more difficult to mobilize. ABSTRACT FROM AUTHOR Copyright of Environmental Geochemistry & Health is the property of Springer Science & Business Media B.V. and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts)","Changes in chromium distribution during the electrodialytic remediation of a Cr (VI)-contaminated soil Abs: A laboratory study has been carried out to determine the feasibility of in situ remediation of chromium (VI)-contaminated soil using electrodialysis in relation to its speciation in soil. This technique is best suited for low-permeability soils or sediments, which may be difficult to remediate by other means and implies the application of a low-intensity direct current to the soil, which is separated from the electrode compartments by ion-exchange membranes. A clayey soil was prepared for use in the experiments and was characterized before being mixed with a solution of potassium dichromate for several days to produce a final Cr content of 4,056 mg/kg of soil dry wt. Remediation tests were carried out under constant-voltage conditions for periods of 7Ã¢â‚¬â€œ14 days and the evolution of applied current to the cell, pH, and conductivity of the electrolytes were recorded periodically. Fractionation of chromium was determined for soil samples before and after remediation using a standardized four-step sequential extraction procedure (SEP) with acetic acid, hydroxylamine, hydrogen peroxide, and aqua regia solutions. Results show that chromium is mobilized from the most labile phases (soluble/exchangeable/carbonate). In a 15 V test, SEP results show that the amount of chromium extracted in the first step drops from 80% to 9%, but also that changes in the total chromium distribution occur during the treatment with some transferred to other soil phases that are more difficult to mobilize. ABSTRACT FROM AUTHOR Copyright of Environmental Geochemistry & Health is the property of Springer Science & Business Media B.V. and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts)"
613155,Manhas et al. 2008,Oxidative degradation of non-ionic surfactant (TritonX-100) by chromium(VI),"Abstract: Degradation of polyoxyethylene chain of non-ionic surfactant (TritonX-100) by chromium(VI) has been studied spectrophotometrically under different experimental conditions. The reaction rate bears a first-order dependence on the [Cr(VI)] under pseudo-first-order conditions, [TritonX-100]Ã¢â€°Â«[Cr(VI)] in presence of 1.16moldm<sup>Ã¢Ë†â€™3</sup> perchloric acid. The observed rate constant (k obs) was 3.3Ãƒâ€”10<sup>Ã¢Ë†â€™4</sup> to 3.5Ãƒâ€”10<sup>Ã¢Ë†â€™4</sup> s<sup>Ã¢Ë†â€™1</sup> and the half-life (t 1/2) was 33Ã¢â‚¬â€œ35min for chromium(VI). The effects of total [TritonX-100] and [H<sup>+</sup>] on the reaction rate were determined. Reducing nature of non-ionic TritonX-100 surfactant is found to be due to the presence of Ã¢â‚¬â€œOH group in the polyoxyethylene chain. It was observed that monomeric and non-ionic micelles of TritonX-100 were oxidized by chromium(VI). When [TritonX-100] was less than its critical micelle concentration (cmc) the k obs values increased from 0.76Ãƒâ€”10<sup>Ã¢Ë†â€™4</sup> to 1.5Ãƒâ€”10<sup>Ã¢Ë†â€™4</sup> s<sup>Ã¢Ë†â€™1</sup>. As the [TritonX-100] was greater than the cmc, the k obs values increases from 2.1Ãƒâ€”10<sup>Ã¢Ë†â€™4</sup> to 8.2Ãƒâ€”10<sup>Ã¢Ë†â€™4</sup> s<sup>Ã¢Ë†â€™1</sup> in presence of constant [HClO4] (1.16moldm<sup>Ã¢Ë†â€™3</sup>) at 40Ã‚Â°C. A comparison was made of the oxidative degradation rates of TritonX-100 with different metal ion oxidants. The order of the effectiveness of different oxidants was as follows: permanganate>diperiodatoargentate(III)>chromium(VI)>cerium(IV). [Copyright 2008 Elsevier] Copyright of Colloids & Surfaces A: Phys. Eng. Asp. is the property of Elsevier Science Publishers B.V. and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts)","Oxidative degradation of non-ionic surfactant (TritonX-100) by chromium(VI) Abs: Abstract: Degradation of polyoxyethylene chain of non-ionic surfactant (TritonX-100) by chromium(VI) has been studied spectrophotometrically under different experimental conditions. The reaction rate bears a first-order dependence on the [Cr(VI)] under pseudo-first-order conditions, [TritonX-100]Ã¢â€°Â«[Cr(VI)] in presence of 1.16moldm<sup>Ã¢Ë†â€™3</sup> perchloric acid. The observed rate constant (k obs) was 3.3Ãƒâ€”10<sup>Ã¢Ë†â€™4</sup> to 3.5Ãƒâ€”10<sup>Ã¢Ë†â€™4</sup> s<sup>Ã¢Ë†â€™1</sup> and the half-life (t 1/2) was 33Ã¢â‚¬â€œ35min for chromium(VI). The effects of total [TritonX-100] and [H<sup>+</sup>] on the reaction rate were determined. Reducing nature of non-ionic TritonX-100 surfactant is found to be due to the presence of Ã¢â‚¬â€œOH group in the polyoxyethylene chain. It was observed that monomeric and non-ionic micelles of TritonX-100 were oxidized by chromium(VI). When [TritonX-100] was less than its critical micelle concentration (cmc) the k obs values increased from 0.76Ãƒâ€”10<sup>Ã¢Ë†â€™4</sup> to 1.5Ãƒâ€”10<sup>Ã¢Ë†â€™4</sup> s<sup>Ã¢Ë†â€™1</sup>. As the [TritonX-100] was greater than the cmc, the k obs values increases from 2.1Ãƒâ€”10<sup>Ã¢Ë†â€™4</sup> to 8.2Ãƒâ€”10<sup>Ã¢Ë†â€™4</sup> s<sup>Ã¢Ë†â€™1</sup> in presence of constant [HClO4] (1.16moldm<sup>Ã¢Ë†â€™3</sup>) at 40Ã‚Â°C. A comparison was made of the oxidative degradation rates of TritonX-100 with different metal ion oxidants. The order of the effectiveness of different oxidants was as follows: permanganate>diperiodatoargentate(III)>chromium(VI)>cerium(IV). [Copyright 2008 Elsevier] Copyright of Colloids & Surfaces A: Phys. Eng. Asp. is the property of Elsevier Science Publishers B.V. and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts)"
613137,Mancuso et al. 2008,Postdeployment Evaluation of Health Risk Communication after Exposure to a Toxic Industrial Chemical,"Increasing emphasis is being placed on the appropriate communication of deployment-related risks among military service members. This report validates risk communication on the postdeployment health assessment (PDHA), in the context of a known, low-level exposure to a toxic industrial chemical. In late 2003. 245 soldiers were exposed to hexavalent chromium at an industrial site in Iraq; of those, 227 had completed PDHAs on file for review. Despite being directed to document this exposure upon redeployment, only 55 soldiers (24.2%) specifically reported chromium exposure. Increasing age and time at the industrial site were associated with increased reporting of exposure. Although providers documented deployment exposure concerns for only 65.4% of this population, this was much more often than for other redeploying service members. The PDHA is a risk assessment and risk communication tool that has sources of misclassification, and results must be interpreted with caution when individual or population occupational and environmental risks resulting from deployment are assessed. [ABSTRACT FROM AUTHOR] Copyright of Military Medicine is the property of Association of Military Surgeons of the United States and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts)","Postdeployment Evaluation of Health Risk Communication after Exposure to a Toxic Industrial Chemical Abs: Increasing emphasis is being placed on the appropriate communication of deployment-related risks among military service members. This report validates risk communication on the postdeployment health assessment (PDHA), in the context of a known, low-level exposure to a toxic industrial chemical. In late 2003. 245 soldiers were exposed to hexavalent chromium at an industrial site in Iraq; of those, 227 had completed PDHAs on file for review. Despite being directed to document this exposure upon redeployment, only 55 soldiers (24.2%) specifically reported chromium exposure. Increasing age and time at the industrial site were associated with increased reporting of exposure. Although providers documented deployment exposure concerns for only 65.4% of this population, this was much more often than for other redeploying service members. The PDHA is a risk assessment and risk communication tool that has sources of misclassification, and results must be interpreted with caution when individual or population occupational and environmental risks resulting from deployment are assessed. [ABSTRACT FROM AUTHOR] Copyright of Military Medicine is the property of Association of Military Surgeons of the United States and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts)"
611900,Lewinska et al. 2008,The nitroxide antioxidant Tempol affects metal-induced cyto- and genotoxicity in human lymphocytes in vitro,"Abstract: Stable, membrane-permeating nitroxide radicals have been reported to possess antioxidant activity in various experimental systems while, in parallel, they have been considered to be evidently harmful oxidants. The aim of this study was to evaluate the role of the piperidine nitroxide 4-hydroxy-2,2,6,6-tetramethylpiperidine-1-oxyl (Tempol) in the modulation of cyto- and genotoxicity in human lymphocytes in vitro by cadmium and chromium, which depend, at least in part, on formation of reactive oxygen species. The cytokinesis-block micronucleus (CBMN) assay to measure micronucleus (MN) formation, the nuclear division index (NDI) and the percentage of apoptotic and necrotic cells were assessed after exposure human lymphocytes to Cd(II), Cr(III) and Cr(VI) or co-incubation with these metals and Tempol. We found a significant ability of 5Ã¢â‚¬â€œ50ÃŽÂ¼M Tempol to diminish toxic effects of the agents tested. In every system studied, Tempol decreased the micronucleus frequency and the percentage of apoptotic and necrotic cells, while it increased the nuclear division index (p <0.05). We observed adverse effects when 0.1Ã¢â‚¬â€œ1mM Tempol alone was used: inhibition of cell growth, induction of apoptotic and necrotic cell death and chromosomal damage (p <0.05). Collectively, we demonstrated that Tempol can be considered as a potent anti-apoptotic and antigenotoxic agent, but also as a cytotoxic and clastogenic chemical, depending on the concentration applied. [Copyright 2008 Elsevier] Copyright of Mutation Research/Genetic Toxicology & Environmental Mutagenesis is the property of Elsevier Science Publishers B.V. and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts)","The nitroxide antioxidant Tempol affects metal-induced cyto- and genotoxicity in human lymphocytes in vitro Abs: Abstract: Stable, membrane-permeating nitroxide radicals have been reported to possess antioxidant activity in various experimental systems while, in parallel, they have been considered to be evidently harmful oxidants. The aim of this study was to evaluate the role of the piperidine nitroxide 4-hydroxy-2,2,6,6-tetramethylpiperidine-1-oxyl (Tempol) in the modulation of cyto- and genotoxicity in human lymphocytes in vitro by cadmium and chromium, which depend, at least in part, on formation of reactive oxygen species. The cytokinesis-block micronucleus (CBMN) assay to measure micronucleus (MN) formation, the nuclear division index (NDI) and the percentage of apoptotic and necrotic cells were assessed after exposure human lymphocytes to Cd(II), Cr(III) and Cr(VI) or co-incubation with these metals and Tempol. We found a significant ability of 5Ã¢â‚¬â€œ50ÃŽÂ¼M Tempol to diminish toxic effects of the agents tested. In every system studied, Tempol decreased the micronucleus frequency and the percentage of apoptotic and necrotic cells, while it increased the nuclear division index (p <0.05). We observed adverse effects when 0.1Ã¢â‚¬â€œ1mM Tempol alone was used: inhibition of cell growth, induction of apoptotic and necrotic cell death and chromosomal damage (p <0.05). Collectively, we demonstrated that Tempol can be considered as a potent anti-apoptotic and antigenotoxic agent, but also as a cytotoxic and clastogenic chemical, depending on the concentration applied. [Copyright 2008 Elsevier] Copyright of Mutation Research/Genetic Toxicology & Environmental Mutagenesis is the property of Elsevier Science Publishers B.V. and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts)"
610947,K'Owino et al. 2007,Tuning the surfaces of palladium nanoparticles for the catalytic conversion of Cr(VI) to Cr(III),"This work reports the feasibility of using Pd nanoparticles as innovative catalysts in the conversion of reducible contaminants from toxic to benign forms. Cr(VI) is a known carcinogen while the trivalent chromium salts are believed to be non-toxic. The ability of Pd nanoparticles to catalyze the rapid reduction of Cr(VI) to Cr(m) using reactive sulfur intermediates produced in situ was therefore studied. Using a microchamber set at 130 degrees C, the reduction mixture consists of palladium nanoparticles and sulfur (PdNPs/S), which generated highly reducing sulfur intermediates that effected the reduction of Cr(VI) to Cr(m) by 1st order reaction kinetics. UV-visible spectroscopy and cyclic voltammetry were employed to monitor the reduction process. The results showed that 99.8% of 400 mu M Cr(VI) was reduced to Cr(m) by PdNPs/S in one hour compared to 2.1 % by a control experiment consisting of sulfur only. The rate of Cr(VI) reduction was found to be dependent on temperature and pH and was greatly enhanced by the addition of PdNPs. Subsequent application of this approach in the reduction of Cr(VI) in soil and aqueous media was conducted. In contrast to the control experiments with and without PdNPs or Sulfur, greater than 92% conversion rate was obtained in the presence of PdNPs/S within I hour. This represents over a 500-fold improvement in conversion rate compared to current microbial approaches. XPS analysis provided the confirmation regarding the oxidation states of Cr(VI), Cr(m) and the nature of the reactive intermediates. This work offers PdNPs/S as a new interface for the reduction of high oxidation state heavy metal pollutants.","Tuning the surfaces of palladium nanoparticles for the catalytic conversion of Cr(VI) to Cr(III) Abs: This work reports the feasibility of using Pd nanoparticles as innovative catalysts in the conversion of reducible contaminants from toxic to benign forms. Cr(VI) is a known carcinogen while the trivalent chromium salts are believed to be non-toxic. The ability of Pd nanoparticles to catalyze the rapid reduction of Cr(VI) to Cr(m) using reactive sulfur intermediates produced in situ was therefore studied. Using a microchamber set at 130 degrees C, the reduction mixture consists of palladium nanoparticles and sulfur (PdNPs/S), which generated highly reducing sulfur intermediates that effected the reduction of Cr(VI) to Cr(m) by 1st order reaction kinetics. UV-visible spectroscopy and cyclic voltammetry were employed to monitor the reduction process. The results showed that 99.8% of 400 mu M Cr(VI) was reduced to Cr(m) by PdNPs/S in one hour compared to 2.1 % by a control experiment consisting of sulfur only. The rate of Cr(VI) reduction was found to be dependent on temperature and pH and was greatly enhanced by the addition of PdNPs. Subsequent application of this approach in the reduction of Cr(VI) in soil and aqueous media was conducted. In contrast to the control experiments with and without PdNPs or Sulfur, greater than 92% conversion rate was obtained in the presence of PdNPs/S within I hour. This represents over a 500-fold improvement in conversion rate compared to current microbial approaches. XPS analysis provided the confirmation regarding the oxidation states of Cr(VI), Cr(m) and the nature of the reactive intermediates. This work offers PdNPs/S as a new interface for the reduction of high oxidation state heavy metal pollutants."
610135,Keane et al. 2009,Hexavalent chromium content in stainless steel welding fumes is dependent on the welding process and shield gas type,"Occupational exposure to welding fumes is a known health hazard. To isolate elements in stainless steel welding fumes with high potential for adverse health outcomes, fumes were generated using a robotic gas metal arc system, using four shield gases of varying oxygen content. The objective was to measure Cr-VI concentrations in a broad spectrum of gas metal arc welding processes, and identify processes of exceptionally high or low Cr-VI content. The gases used were 95% Ar/5% O-2, 98% Ar/2% O-2, 95% Ar/5% CO2, and 75% He/25% Ar. The welder was operated in axial spray mode (Ar/O-2, Ar/CO2), short-circuit (SC) mode (Ar/CO2 low voltage and He/Ar), and pulsed axial-spray mode (98% Ar/2% O-2). Results indicate large differences in Cr-VI in the fumes, with Ar/O-2 (Pulsed) > Ar/O-2 > Ar/CO2 > Ar/CO2 (SC) > He/Ar; values were 3000 +/- 300, 2800 +/- 85, 2600 +/- 120, 1400 +/- 190, and 320 +/- 290 ppm respectively (means +/- standard errors for 2 runs and 3 replicates per run). Respective rates of Cr-VI generation were 1.5, 3.2, 4.4, 1.3, and 0.46 mu g/min; generation rates were also calculated in terms of mu g Cr-VI per metre of wire used. The generation rates of Cr-VI increased with increasing O-3 concentrations. Particle size measurements indicated similar distributions, but somewhat higher > 0.6 mu m fractions for the short-circuit mode samples. Fumes were also sampled into 2 selected size ranges, a microspatter fraction (>= 0.6 mu m) and a fine (<0.6 mu m) fraction; analysis indicated that Cr-VI is primarily associated with particles <.6 mu m. The conclusion of the study is that Cr-VI concentrations vary significantly with welding type and shield gas type, and this presents an opportunity to tailor welding practices to lessen Cr-VI exposures in workplaces by selecting low Cr-VI-generating processes. Short-circuit processes generated less Cr-VI than axial-spray methods, and inert gas shielding gave lower Cr-VI content than shielding with active gases. A short circuit He/Ar shielded process and a pulsed axial spray Ar/O-2 process were both identified as having substantially lower Cr-VI generation rates per unit of wire used relative to the other processes studied.","Hexavalent chromium content in stainless steel welding fumes is dependent on the welding process and shield gas type Abs: Occupational exposure to welding fumes is a known health hazard. To isolate elements in stainless steel welding fumes with high potential for adverse health outcomes, fumes were generated using a robotic gas metal arc system, using four shield gases of varying oxygen content. The objective was to measure Cr-VI concentrations in a broad spectrum of gas metal arc welding processes, and identify processes of exceptionally high or low Cr-VI content. The gases used were 95% Ar/5% O-2, 98% Ar/2% O-2, 95% Ar/5% CO2, and 75% He/25% Ar. The welder was operated in axial spray mode (Ar/O-2, Ar/CO2), short-circuit (SC) mode (Ar/CO2 low voltage and He/Ar), and pulsed axial-spray mode (98% Ar/2% O-2). Results indicate large differences in Cr-VI in the fumes, with Ar/O-2 (Pulsed) > Ar/O-2 > Ar/CO2 > Ar/CO2 (SC) > He/Ar; values were 3000 +/- 300, 2800 +/- 85, 2600 +/- 120, 1400 +/- 190, and 320 +/- 290 ppm respectively (means +/- standard errors for 2 runs and 3 replicates per run). Respective rates of Cr-VI generation were 1.5, 3.2, 4.4, 1.3, and 0.46 mu g/min; generation rates were also calculated in terms of mu g Cr-VI per metre of wire used. The generation rates of Cr-VI increased with increasing O-3 concentrations. Particle size measurements indicated similar distributions, but somewhat higher > 0.6 mu m fractions for the short-circuit mode samples. Fumes were also sampled into 2 selected size ranges, a microspatter fraction (>= 0.6 mu m) and a fine (<0.6 mu m) fraction; analysis indicated that Cr-VI is primarily associated with particles <.6 mu m. The conclusion of the study is that Cr-VI concentrations vary significantly with welding type and shield gas type, and this presents an opportunity to tailor welding practices to lessen Cr-VI exposures in workplaces by selecting low Cr-VI-generating processes. Short-circuit processes generated less Cr-VI than axial-spray methods, and inert gas shielding gave lower Cr-VI content than shielding with active gases. A short circuit He/Ar shielded process and a pulsed axial spray Ar/O-2 process were both identified as having substantially lower Cr-VI generation rates per unit of wire used relative to the other processes studied."
607903,Heung et al. 2007,Emissions of chromium(VI) from arc welding,"The presence of Cr in the +6 oxidation state (Cr[VI]) is still observed in ambient air samples in California despite steps taken to reduce emissions from plating operations. One known source of emission of Cr(VI) is welding, especially with high Cr-content materials, such as stainless steels. An experimental effort was undertaken to expand and update Cr(VI) emission factors by conducting tests on four types of arc-welding operations: gas-metal arc welding (GMAW), shielded metal arc welding (SMAW), flux-core arc welding, and pulsed GMAW. Standard American Welding Society hood results were compared with a total enclosure method that permitted isokinetic sampling for particle size-cut measurement, as well as total collection of the aerosol. The fraction of Cr(VI) emitted per unit mass of Cr electrode consumed was determined. Consistent with AP-42 data, initial results indicate that a significant fraction of the total Cr in the aerosol is in the +6 oxidation state. The fraction of Cr(VI) and total aerosol mass produced by the different arc welding methods varies with the type of welding process used. Self-shielded electrodes that do not use a shield gas, for example, SMAW, produce greater amounts of Cr(VI) per unit mass of electrode consumed. The formation of Cr(VI) from standard electrode wires used for welding mild steel was below the method detection limit after eliminating an artifact in the analytical method used.","Emissions of chromium(VI) from arc welding Abs: The presence of Cr in the +6 oxidation state (Cr[VI]) is still observed in ambient air samples in California despite steps taken to reduce emissions from plating operations. One known source of emission of Cr(VI) is welding, especially with high Cr-content materials, such as stainless steels. An experimental effort was undertaken to expand and update Cr(VI) emission factors by conducting tests on four types of arc-welding operations: gas-metal arc welding (GMAW), shielded metal arc welding (SMAW), flux-core arc welding, and pulsed GMAW. Standard American Welding Society hood results were compared with a total enclosure method that permitted isokinetic sampling for particle size-cut measurement, as well as total collection of the aerosol. The fraction of Cr(VI) emitted per unit mass of Cr electrode consumed was determined. Consistent with AP-42 data, initial results indicate that a significant fraction of the total Cr in the aerosol is in the +6 oxidation state. The fraction of Cr(VI) and total aerosol mass produced by the different arc welding methods varies with the type of welding process used. Self-shielded electrodes that do not use a shield gas, for example, SMAW, produce greater amounts of Cr(VI) per unit mass of electrode consumed. The formation of Cr(VI) from standard electrode wires used for welding mild steel was below the method detection limit after eliminating an artifact in the analytical method used."
606708,Goldoni et al. 2008,Chromium in exhaled breath condensate and pulmonary tissue of non-small cell lung cancer patients,"Chromium in exhaled breath condensate (EBC) has recently been proposed as a biomarker of pulmonary exposure. The aim of this study was to measure the Cr levels in the EBC and pulmonary tissue of patients with early, operable non-small cell lung cancer (NSCLC) who had not been occupationally exposed to Cr before and after tumour resection and to correlate Cr in lung tissue with that in EBC. Cr levels in the EBC and pulmonary tissue of 20 NSCLC patients were measured by means of electrothermal atomic absorption before and after tumour resection. Cr levels were also measured in the urine of 15 of these patients. The pre-surgery EBC Cr levels of the NSCLC patients were not different from those of the controls, but both EBC and urinary Cr levels increased after surgery. There was a significant correlation between Cr levels in EBC and pulmonary tissue ( R = 0.55, P = 0.01), but not between these and urinary Cr levels. Cr levels in EBC and urine of NSCLC patients were increased after surgical intervention. Measured Cr EBC levels were by one order of magnitude lower than those observed in moderately exposed workers. This fact, together with the correlation between Cr in EBC and in pulmonary tissue, confirms that EBC is a promising biological fluid to test pulmonary exposure to Cr, giving complementary information to that provided by urinary Cr, not correlated with EBC and tissue. ABSTRACT FROM AUTHOR Copyright of International Archives of Occupational & Environmental Health is the property of Springer Science & Business Media B.V. and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts)","Chromium in exhaled breath condensate and pulmonary tissue of non-small cell lung cancer patients Abs: Chromium in exhaled breath condensate (EBC) has recently been proposed as a biomarker of pulmonary exposure. The aim of this study was to measure the Cr levels in the EBC and pulmonary tissue of patients with early, operable non-small cell lung cancer (NSCLC) who had not been occupationally exposed to Cr before and after tumour resection and to correlate Cr in lung tissue with that in EBC. Cr levels in the EBC and pulmonary tissue of 20 NSCLC patients were measured by means of electrothermal atomic absorption before and after tumour resection. Cr levels were also measured in the urine of 15 of these patients. The pre-surgery EBC Cr levels of the NSCLC patients were not different from those of the controls, but both EBC and urinary Cr levels increased after surgery. There was a significant correlation between Cr levels in EBC and pulmonary tissue ( R = 0.55, P = 0.01), but not between these and urinary Cr levels. Cr levels in EBC and urine of NSCLC patients were increased after surgical intervention. Measured Cr EBC levels were by one order of magnitude lower than those observed in moderately exposed workers. This fact, together with the correlation between Cr in EBC and in pulmonary tissue, confirms that EBC is a promising biological fluid to test pulmonary exposure to Cr, giving complementary information to that provided by urinary Cr, not correlated with EBC and tissue. ABSTRACT FROM AUTHOR Copyright of International Archives of Occupational & Environmental Health is the property of Springer Science & Business Media B.V. and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts)"
606353,Ge et al. 2008,Chromium (VI) induces insulin resistance in 3T3-L1 adipocytes through elevated reactive oxygen species generation,"Reactive oxygen species (ROS) have been proposed to be involved in the development of insulin resistance, although the exact molecular link between ROS and insulin resistance remains to be determined. Chromium (Cr(VI)) is known as an inducer of ROS. Therefore, this study examined whether Cr(VI) could induce insulin resistance. It demonstrated that Cr(VI) treatment significantly inhibited insulin-stimulated glucose uptake and attenuated insulin signalling. Moreover, Cr(VI) treatment markedly increased the intracellular levels of superoxide anion, hydrogen peroxide and hydroxyl radical. N-acetylcysteine, superoxide dismutase and catalase can block the ROS generation and alleviate the insulin resistance induced by Cr(VI) treatment. In addition, Cr(VI) treatment induced endoplasmic reticulum (ER) stress and JNK activation and these effects were diminished by N-acetylcysteine. These results suggested that ROS generation through Cr(VI) treatment cause ER stress, JNK activation and insulin resistance in adipocytes. Therefore, the oxidative stress could be a potential interventional target for insulin-resistance related diseases. [ABSTRACT FROM AUTHOR] Copyright of Free Radical Research is the property of Taylor & Francis Ltd and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts)","Chromium (VI) induces insulin resistance in 3T3-L1 adipocytes through elevated reactive oxygen species generation Abs: Reactive oxygen species (ROS) have been proposed to be involved in the development of insulin resistance, although the exact molecular link between ROS and insulin resistance remains to be determined. Chromium (Cr(VI)) is known as an inducer of ROS. Therefore, this study examined whether Cr(VI) could induce insulin resistance. It demonstrated that Cr(VI) treatment significantly inhibited insulin-stimulated glucose uptake and attenuated insulin signalling. Moreover, Cr(VI) treatment markedly increased the intracellular levels of superoxide anion, hydrogen peroxide and hydroxyl radical. N-acetylcysteine, superoxide dismutase and catalase can block the ROS generation and alleviate the insulin resistance induced by Cr(VI) treatment. In addition, Cr(VI) treatment induced endoplasmic reticulum (ER) stress and JNK activation and these effects were diminished by N-acetylcysteine. These results suggested that ROS generation through Cr(VI) treatment cause ER stress, JNK activation and insulin resistance in adipocytes. Therefore, the oxidative stress could be a potential interventional target for insulin-resistance related diseases. [ABSTRACT FROM AUTHOR] Copyright of Free Radical Research is the property of Taylor & Francis Ltd and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts)"
604308,Demoisson et al. 2007,Investigation of pyrite oxidation by hexavalent chromium: Solution species and surface chemistry,Pyrite oxidation processes by aqueous Cr(VI) were investigated at 25@?^oC under an argon atmosphere. Synthetic pyrite suspensions (6 g@?L^-^1) were reacted for 20 h with a range of Cr(VI) solutions from 0 to 700 @mM and at pH 2-12. The main...,Investigation of pyrite oxidation by hexavalent chromium: Solution species and surface chemistry Abs: Pyrite oxidation processes by aqueous Cr(VI) were investigated at 25@?^oC under an argon atmosphere. Synthetic pyrite suspensions (6 g@?L^-^1) were reacted for 20 h with a range of Cr(VI) solutions from 0 to 700 @mM and at pH 2-12. The main...
601895,Branco et al. 2008,The Chromate-Inducible chrBACF Operon from the Transposable Element TnOtChr Confers Resistance to Chromium(VI) and Superoxide,"Large-scale industrial use of chromium(VI) has resulted in widespread contamination with carcinogenic chromium(VI). The abilities of microorganisms to survive in these environments and to detoxify chromate require the presence of specific resistance systems. Here we report identification of the transposon-located (TnOtChr) chromate resistance genes from the highly tolerant strain Ochrobactrum tritici 5bvl1 surviving chromate concentrations of >50 mM. The 7,189-bp-long TnOtChr of the mixed Tn21/Tn3 transposon subfamily contains a group of chrB, chrA, chrC, and chrF genes situated between divergently transcribed resolvase and transposase genes. The chrB and chrA genes, but not chrF or chrC, were essential for establishment of high resistance in chromium-sensitive O. tritici. The chr promoter was strongly induced by chromate or dichromate, but it was completely unresponsive to Cr(III), oxidants, sulfate, or other oxyanions. Plasmid reporter experiments identified ChrB as a chromate-sensing regulator of chr expression. Induction of the chr operon suppressed accumulation of cellular Cr through the activity of a chromate efflux pump encoded by chrA. Expression of chrB, chrC, or chrF in an Escherichia coli sodA sodB double mutant restored its aerobic growth in minimal medium and conferred resistance to superoxide-generating agents menadione and paraquat. Nitroblue tetrazolium staining on native gels showed that ChrC protein had superoxide dismutase activity. TnOtChr appears to represent a mobile genetic system for the distribution of the chromate-regulated resistance operon. The presence of three genes protecting against superoxide toxicity should provide an additional survival advantage to TnOtChr-containing cells in the environments with multiple redox-active contaminants. [ABSTRACT FROM AUTHOR] Copyright of Journal of Bacteriology is the property of American Society for Microbiology and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts)","The Chromate-Inducible chrBACF Operon from the Transposable Element TnOtChr Confers Resistance to Chromium(VI) and Superoxide Abs: Large-scale industrial use of chromium(VI) has resulted in widespread contamination with carcinogenic chromium(VI). The abilities of microorganisms to survive in these environments and to detoxify chromate require the presence of specific resistance systems. Here we report identification of the transposon-located (TnOtChr) chromate resistance genes from the highly tolerant strain Ochrobactrum tritici 5bvl1 surviving chromate concentrations of >50 mM. The 7,189-bp-long TnOtChr of the mixed Tn21/Tn3 transposon subfamily contains a group of chrB, chrA, chrC, and chrF genes situated between divergently transcribed resolvase and transposase genes. The chrB and chrA genes, but not chrF or chrC, were essential for establishment of high resistance in chromium-sensitive O. tritici. The chr promoter was strongly induced by chromate or dichromate, but it was completely unresponsive to Cr(III), oxidants, sulfate, or other oxyanions. Plasmid reporter experiments identified ChrB as a chromate-sensing regulator of chr expression. Induction of the chr operon suppressed accumulation of cellular Cr through the activity of a chromate efflux pump encoded by chrA. Expression of chrB, chrC, or chrF in an Escherichia coli sodA sodB double mutant restored its aerobic growth in minimal medium and conferred resistance to superoxide-generating agents menadione and paraquat. Nitroblue tetrazolium staining on native gels showed that ChrC protein had superoxide dismutase activity. TnOtChr appears to represent a mobile genetic system for the distribution of the chromate-regulated resistance operon. The presence of three genes protecting against superoxide toxicity should provide an additional survival advantage to TnOtChr-containing cells in the environments with multiple redox-active contaminants. [ABSTRACT FROM AUTHOR] Copyright of Journal of Bacteriology is the property of American Society for Microbiology and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts)"
599864,Alexopoulos et al. 2008,Biological Monitoring of Hexavalent Chromium and Serum Levels of the Senescence Biomarker Apolipoprotein J/Clusterin in Welders,"Welding fumes contain metals and other toxic substances known or strongly suspected to be related with oxidative stress and premature cellular senescence. Apolipoprotein J/Clusterin (ApoJ/CLU) is a glycoprotein that is differentially regulated in various physiological and disease states including ageing and age-related diseases. In vitro data showed that exposure of human diploid fibroblasts to hexavalent chromium (Cr(VI)) resulted in premature senescence and significant upregulation of the ApoJ/CLU protein. In this study we analyzed blood and urine samples from shipyard industry welders being exposed to different levels of Cr(VI) over a period of five months in order to assay in vivo the relation of ApoJ/CLU serum levels with Cr(VI). Our findings confirmed the previously reported in vitro data since reduction of Cr levels, after a worksite intervention, associated with lower levels of ApoJ/CLU serum levels. We concluded that the human ApoJ/CLU gene is responsive to the acute in vivo oxidative stress induced by heavy metals such as hexavalent chromium. [ABSTRACT FROM AUTHOR] Copyright of Bioinorganic Chemistry & Applications is the property of Hindawi Publishing Corporation and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts)","Biological Monitoring of Hexavalent Chromium and Serum Levels of the Senescence Biomarker Apolipoprotein J/Clusterin in Welders Abs: Welding fumes contain metals and other toxic substances known or strongly suspected to be related with oxidative stress and premature cellular senescence. Apolipoprotein J/Clusterin (ApoJ/CLU) is a glycoprotein that is differentially regulated in various physiological and disease states including ageing and age-related diseases. In vitro data showed that exposure of human diploid fibroblasts to hexavalent chromium (Cr(VI)) resulted in premature senescence and significant upregulation of the ApoJ/CLU protein. In this study we analyzed blood and urine samples from shipyard industry welders being exposed to different levels of Cr(VI) over a period of five months in order to assay in vivo the relation of ApoJ/CLU serum levels with Cr(VI). Our findings confirmed the previously reported in vitro data since reduction of Cr levels, after a worksite intervention, associated with lower levels of ApoJ/CLU serum levels. We concluded that the human ApoJ/CLU gene is responsive to the acute in vivo oxidative stress induced by heavy metals such as hexavalent chromium. [ABSTRACT FROM AUTHOR] Copyright of Bioinorganic Chemistry & Applications is the property of Hindawi Publishing Corporation and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts)"
597702,Bjorge et al. 1996,DNA damage in testicular cells in vitro: The response of rat and human cells to known testicular toxicants,"Abstract of poster presented at the 25th Annual Meeting of the European Environmental Mutagen Society 18-23 June 1995, Noordwijkerhout, The Netherlands","DNA damage in testicular cells in vitro: The response of rat and human cells to known testicular toxicants Abs: Abstract of poster presented at the 25th Annual Meeting of the European Environmental Mutagen Society 18-23 June 1995, Noordwijkerhout, The Netherlands"
597309,Altamirano-Lozano et al. 1998,Effect of metal compounds on boar sperm motility in vitro,,Effect of metal compounds on boar sperm motility in vitro Abs: 
597100,Amlacher 1982,Short-term tests in screening programs of environmental chemical carcinogens,,Short-term tests in screening programs of environmental chemical carcinogens Abs: 
596330,Kerckaert et al. 1996,Use of the Syrian hamster embryo cell transformation assay for determining the carcinogenic potential of heavy metal compounds,"Cobalt sulfate hydrate, gallium arsenide, molybdenum trioxide, vanadium pentoxide, and nickel sulfate heptahydrate were tested in the Syrian hamster embryo (SHE) assay in order to increase the SHE assay database for heavy metals. All five compounds produced significant morphological transformation at one or more doses in a dose-responsive manner. Cobalt sulfate hydrate, gallium arsenide, molybdenum trioxide, and nickel (II) sulfate heptahydrate were all positive with a 24-hr exposure, suggesting direct DNA perturbation. Vanadium pentoxide was negative with a 24-hr exposure, but positive with a 7-day exposure. This pattern of response (24-hr SHE negative/7-day SHE positive) has been seen with other chemicals which have tumor promotion-like characteristics. Since the inception of the use of the SHE cell transformation assay for detecting the neoplastic transformation potential of chemicals, over 42 heavy metal compounds have been tested in this assay. Based on the 24 metal compounds which have been tested in the SHE, Salmonella, and some type of rodent bioassay, the SHE assay is 92% concordant with rodent bioassay carcinogenicity results, including a sensitivity of 95% (21/22) and a specificity of 50% (1/2). At this time, the measure of SHE assay specificity for rodent carcinogenicity of metals is limited by the paucity of metal compounds which are rodent noncarcinogens. The Salmonella assay results are only 33% concordant with the rodent bioassay for these same chemicals. This relatively high concordance between the SHE assay and the rodent bioassay carcinogenicity results demonstrates the utility of the SHE assay for determining the carcinogenic potential of heavy metal compounds in rodent cancer bioassays.","Use of the Syrian hamster embryo cell transformation assay for determining the carcinogenic potential of heavy metal compounds Abs: Cobalt sulfate hydrate, gallium arsenide, molybdenum trioxide, vanadium pentoxide, and nickel sulfate heptahydrate were tested in the Syrian hamster embryo (SHE) assay in order to increase the SHE assay database for heavy metals. All five compounds produced significant morphological transformation at one or more doses in a dose-responsive manner. Cobalt sulfate hydrate, gallium arsenide, molybdenum trioxide, and nickel (II) sulfate heptahydrate were all positive with a 24-hr exposure, suggesting direct DNA perturbation. Vanadium pentoxide was negative with a 24-hr exposure, but positive with a 7-day exposure. This pattern of response (24-hr SHE negative/7-day SHE positive) has been seen with other chemicals which have tumor promotion-like characteristics. Since the inception of the use of the SHE cell transformation assay for detecting the neoplastic transformation potential of chemicals, over 42 heavy metal compounds have been tested in this assay. Based on the 24 metal compounds which have been tested in the SHE, Salmonella, and some type of rodent bioassay, the SHE assay is 92% concordant with rodent bioassay carcinogenicity results, including a sensitivity of 95% (21/22) and a specificity of 50% (1/2). At this time, the measure of SHE assay specificity for rodent carcinogenicity of metals is limited by the paucity of metal compounds which are rodent noncarcinogens. The Salmonella assay results are only 33% concordant with the rodent bioassay for these same chemicals. This relatively high concordance between the SHE assay and the rodent bioassay carcinogenicity results demonstrates the utility of the SHE assay for determining the carcinogenic potential of heavy metal compounds in rodent cancer bioassays."
592286,Xu et al. 2005,Enhancing effect of iron on chromate reduction by Cellulomonas flavigena,"Cr(VI) is considerably toxic and the detoxification of Cr(VI) is of great importance. This study investigated the effect of iron on Cr(VI) reduction by Cellulomonas flavigena. The results demonstrated that addition of FeCl3 or lepidocrocite promoted Cr(VI) reduction, with the reduction ratio of above 90 and 80% achieved, respectively, but addition of hematite did not lead to the increase of reduction ratio, which suggests that the effect of iron on chromate reduction appears different with the diversity of iron-oxides. In this study, the effect of initial Cr(VI) and Fe(III) concentration on Cr(VI) reduction and the change of pH value were also investigated. The reduction ratio increased with the increase of the initial concentration ratio of Fe(III)/Cr(VI). The value of pH gradually increased from 7.0 to around 9.0.","Enhancing effect of iron on chromate reduction by Cellulomonas flavigena Abs: Cr(VI) is considerably toxic and the detoxification of Cr(VI) is of great importance. This study investigated the effect of iron on Cr(VI) reduction by Cellulomonas flavigena. The results demonstrated that addition of FeCl3 or lepidocrocite promoted Cr(VI) reduction, with the reduction ratio of above 90 and 80% achieved, respectively, but addition of hematite did not lead to the increase of reduction ratio, which suggests that the effect of iron on chromate reduction appears different with the diversity of iron-oxides. In this study, the effect of initial Cr(VI) and Fe(III) concentration on Cr(VI) reduction and the change of pH value were also investigated. The reduction ratio increased with the increase of the initial concentration ratio of Fe(III)/Cr(VI). The value of pH gradually increased from 7.0 to around 9.0."
587820,Thacker et al. 2007,Reduction of chromate by cell-free extract of Brucella sp. isolated from Cr(VI) contaminated sites,"A locally isolated gram negative strain of Brucella sp., identified by biochemical methods and 16SrRNA analysis, reduced chromate to 100%, 94.1%, 93.2%, 66.9% and 41.6% at concentrations of 50, 100, 150, 200 and 300Â mgÂ l-1, respectively at pH 7 and temperature 37Â Â°C. Increasing concentrations of Cr(VI) in the medium lowered the growth rate but could not be directly correlated with the amount of Cr(VI) reduced. The strain also exhibited multiple heavy metal (Ni,Â Zn,Â Hg,Â Pb,Â Co) tolerance and resistance to various antibiotics. Assay with crude cell-free extracts demonstrated that the hexavalent chromium reduction was mainly associated with the soluble fraction of the cell. High Cr(VI) concentration resistance and high Cr(VI) reducing ability of the strain make it a suitable candidate for bioremediation.","Reduction of chromate by cell-free extract of Brucella sp. isolated from Cr(VI) contaminated sites Abs: A locally isolated gram negative strain of Brucella sp., identified by biochemical methods and 16SrRNA analysis, reduced chromate to 100%, 94.1%, 93.2%, 66.9% and 41.6% at concentrations of 50, 100, 150, 200 and 300Â mgÂ l-1, respectively at pH 7 and temperature 37Â Â°C. Increasing concentrations of Cr(VI) in the medium lowered the growth rate but could not be directly correlated with the amount of Cr(VI) reduced. The strain also exhibited multiple heavy metal (Ni,Â Zn,Â Hg,Â Pb,Â Co) tolerance and resistance to various antibiotics. Assay with crude cell-free extracts demonstrated that the hexavalent chromium reduction was mainly associated with the soluble fraction of the cell. High Cr(VI) concentration resistance and high Cr(VI) reducing ability of the strain make it a suitable candidate for bioremediation."
587819,Thacker et al. 2006,Hexavalent chromium reduction by Providencia sp,"A gram-negative chromate reducing bacteria (UTDM314) was isolated from the contaminated sites of chemical industries, which is identified as Providencia sp. by biochemical methods and 16SrRNA analysis. The bacterial isolate could grow and reduce chromate to 100% at a concentration ranging from 100-300Â mg/l and 99.31% at a concentration of 400Â mg/l, pH 7 and temperature 37Â Â°C. It also exhibited multiple heavy metal (Ni, Zn, Hg, Pb, Co) tolerance. Assay with resting cells, permeablized cells (treated with toluene and Triton X100) and crude cell free extracts demonstrated that the hexavalent chromium reduction is mainly associated with the soluble fraction of the cell. Providencia sp. has a great potential for bioremediation of Cr(VI) containing wastes. This approach permits selection of bacterial strains, which could be used for specific environmental clean up operations.","Hexavalent chromium reduction by Providencia sp Abs: A gram-negative chromate reducing bacteria (UTDM314) was isolated from the contaminated sites of chemical industries, which is identified as Providencia sp. by biochemical methods and 16SrRNA analysis. The bacterial isolate could grow and reduce chromate to 100% at a concentration ranging from 100-300Â mg/l and 99.31% at a concentration of 400Â mg/l, pH 7 and temperature 37Â Â°C. It also exhibited multiple heavy metal (Ni, Zn, Hg, Pb, Co) tolerance. Assay with resting cells, permeablized cells (treated with toluene and Triton X100) and crude cell free extracts demonstrated that the hexavalent chromium reduction is mainly associated with the soluble fraction of the cell. Providencia sp. has a great potential for bioremediation of Cr(VI) containing wastes. This approach permits selection of bacterial strains, which could be used for specific environmental clean up operations."
583387,Santoyo and  Strathern 2008,Non-homologous end joining is important for repair of Cr(VI)-induced DNA damage in Saccharomyces cerevisiae,"Summary Hexavalent chromium is known to be a potent carcinogen that leads to many different DNA lesions, including DNA-protein crosslinks, and single- and double-strand breaks. In Saccharomyces cerevisiae, DNA double-strand breaks are mainly repaired by either homologous recombination (HR) or non-homologous end-joining (NHEJ) repair pathways. Here, we show that mutants deficient in NHEJ (yku70[Delta], rad50[Delta], dnl4[Delta], mre11[Delta], xrs2[Delta]) of S. cerevisiae are more sensitive to Cr(VI) toxic effects than wild-type cells. Also, a deletion mutant of SAE2 showed a similar sensitivity to Cr(VI), even though it has no apparent direct role in NHEJ. We also found that double mutants in HR and NHEJ (yku70[Delta]/rad52[Delta], rad50[Delta]/rad52[Delta], dnl4[Delta]/rad52[Delta], mre11[Delta]/rad52[Delta], xrs2[Delta]/rad52[Delta]) are synergistically more sensitive to Cr(VI) exposure than any of the single mutants, indicating that both repair pathways are involved in the repair of Cr(VI)-induced lesions. Finally, when the NHEJ mutants were exposed to Cr(VI) under anaerobic growth conditions, Cr(VI) toxicity was suppressed.","Non-homologous end joining is important for repair of Cr(VI)-induced DNA damage in Saccharomyces cerevisiae Abs: Summary Hexavalent chromium is known to be a potent carcinogen that leads to many different DNA lesions, including DNA-protein crosslinks, and single- and double-strand breaks. In Saccharomyces cerevisiae, DNA double-strand breaks are mainly repaired by either homologous recombination (HR) or non-homologous end-joining (NHEJ) repair pathways. Here, we show that mutants deficient in NHEJ (yku70[Delta], rad50[Delta], dnl4[Delta], mre11[Delta], xrs2[Delta]) of S. cerevisiae are more sensitive to Cr(VI) toxic effects than wild-type cells. Also, a deletion mutant of SAE2 showed a similar sensitivity to Cr(VI), even though it has no apparent direct role in NHEJ. We also found that double mutants in HR and NHEJ (yku70[Delta]/rad52[Delta], rad50[Delta]/rad52[Delta], dnl4[Delta]/rad52[Delta], mre11[Delta]/rad52[Delta], xrs2[Delta]/rad52[Delta]) are synergistically more sensitive to Cr(VI) exposure than any of the single mutants, indicating that both repair pathways are involved in the repair of Cr(VI)-induced lesions. Finally, when the NHEJ mutants were exposed to Cr(VI) under anaerobic growth conditions, Cr(VI) toxicity was suppressed."
574493,Mazzer et al. 2007,Mechanisms of DNA damage and insight into mutations by chromium(VI) in the presence of glutathione,"The mechanisms of hexavalent chromium(VI) induced DNA damage were unveiled by detecting products of single- and double-stranded DNA in the presence of glutathione. The absence of a detectable hydroxyl radical in the reactions indicates that DNA damage was exclusively by hypervalent chromium species. Polyacrylamide gel electrophoresis (PAGE) experiments with 32-mer single-stranded oligonucleotide and its complementary duplex revealed cleavages largely at purine bases with significant enhancement of such cleavages in the presence of a base. Quantitative estimations of bases released by HPLC before and after enzymatic digestion with exonucleases unequivocally established the excessive release of purine bases. This release was accompanied by the concomitant formation of phosphoglycolate as characterized by liquid chromatography-mass spectrometry (LC-MS). These data connote that the preponderance DNA damage is due to an oxidation specifically at H4' of the ribose moiety leading to the formation of apurinic sites. In addition to the oxidation at H4', DNA oxidation was also initiated through H5' site as evidenced by the identification of furfural. This pathway appears to be non-selective and more abundant for ssDNA as cleavages were observed at both purine and pyrimidine bases. Finally, the detection of guanidinohydantoin as a minor product points the involvement of an oxygen activated hypervalent chromium species, perhaps a peroxo-chromium species. Both major and minor pathways lead to cleavages at purine sites for ds-DNA and are consistent with the observation that DNA cleavage was enhanced in the presence of a base. In contrast, when hydrogen peroxide was added to the reactions, random DNA cleavages were apparent indicating involvement of multiple species including a hydroxyl radical. These data pinpoint mutation mechanisms induced by chromium(VI) in the presence of glutathione due to transversion either by inserting the wrong bases opposite to the apurinic sites during replication or by purine-purine mismatch.","Mechanisms of DNA damage and insight into mutations by chromium(VI) in the presence of glutathione Abs: The mechanisms of hexavalent chromium(VI) induced DNA damage were unveiled by detecting products of single- and double-stranded DNA in the presence of glutathione. The absence of a detectable hydroxyl radical in the reactions indicates that DNA damage was exclusively by hypervalent chromium species. Polyacrylamide gel electrophoresis (PAGE) experiments with 32-mer single-stranded oligonucleotide and its complementary duplex revealed cleavages largely at purine bases with significant enhancement of such cleavages in the presence of a base. Quantitative estimations of bases released by HPLC before and after enzymatic digestion with exonucleases unequivocally established the excessive release of purine bases. This release was accompanied by the concomitant formation of phosphoglycolate as characterized by liquid chromatography-mass spectrometry (LC-MS). These data connote that the preponderance DNA damage is due to an oxidation specifically at H4' of the ribose moiety leading to the formation of apurinic sites. In addition to the oxidation at H4', DNA oxidation was also initiated through H5' site as evidenced by the identification of furfural. This pathway appears to be non-selective and more abundant for ssDNA as cleavages were observed at both purine and pyrimidine bases. Finally, the detection of guanidinohydantoin as a minor product points the involvement of an oxygen activated hypervalent chromium species, perhaps a peroxo-chromium species. Both major and minor pathways lead to cleavages at purine sites for ds-DNA and are consistent with the observation that DNA cleavage was enhanced in the presence of a base. In contrast, when hydrogen peroxide was added to the reactions, random DNA cleavages were apparent indicating involvement of multiple species including a hydroxyl radical. These data pinpoint mutation mechanisms induced by chromium(VI) in the presence of glutathione due to transversion either by inserting the wrong bases opposite to the apurinic sites during replication or by purine-purine mismatch."
565754,Hsu et al. 2007,The removal and recovery of Cr(VI) by Li/Al layered double hydroxide (LDH),"Hexavalent Cr has been identified as one of the toxic metals commonly present in industrial effluents. Among the treatment techniques developed for removing Cr(VI) from waste waters, sorption is most commonly applied, due to its simplicity and efficiency. However, few adsorbents can be recycled and reused cost-effectively. In this study, the removal and recovery of Cr(VI) from water using Li/Al LDH was investigated. The removal of Cr(VI) by Li/Al LDH was evaluated in a batch mode. The results demonstrated that Cr(VI) adsorption onto Li/Al LDH occurs by replacing the Cl- that originally exists in the interlayer of the adsorbent. The degree of Cr(VI) adsorption observed for Li/Al LDH was relatively high and the process occurred rapidly; however, a portion of adsorbed Cr(VI) was gradually desorbed, due to the Li de-intercalation of Li/Al LDH. Lithium de-intercalation from Li/Al LDH with interlayer Cl- and interlayer Cr(VI) follows the first order kinetics and has the activation energies of 76.6 and 41.5Â kJÂ mol-1, respectively. The properties of thermal unstablility and the high adsorption capacity of Li/Al LDH may lead to the development of an innovative technique for the removal of Cr(VI) from Cr(VI)-containing wastewater. That is, Li/Al LDH may be used as an effective adsorbent for the adsorption of Cr(VI) in an ambient environment. Following the adsorptive process, the adsorbed Cr(VI) may be released, using heated water to treat the Cr(VI)-containing Li/Al LDH particles. Through this hydrothermal treatment of the used adsorbent, Cr(VI) can be recovered and the solid product (gibbsite) can be recycled for further use.","The removal and recovery of Cr(VI) by Li/Al layered double hydroxide (LDH) Abs: Hexavalent Cr has been identified as one of the toxic metals commonly present in industrial effluents. Among the treatment techniques developed for removing Cr(VI) from waste waters, sorption is most commonly applied, due to its simplicity and efficiency. However, few adsorbents can be recycled and reused cost-effectively. In this study, the removal and recovery of Cr(VI) from water using Li/Al LDH was investigated. The removal of Cr(VI) by Li/Al LDH was evaluated in a batch mode. The results demonstrated that Cr(VI) adsorption onto Li/Al LDH occurs by replacing the Cl- that originally exists in the interlayer of the adsorbent. The degree of Cr(VI) adsorption observed for Li/Al LDH was relatively high and the process occurred rapidly; however, a portion of adsorbed Cr(VI) was gradually desorbed, due to the Li de-intercalation of Li/Al LDH. Lithium de-intercalation from Li/Al LDH with interlayer Cl- and interlayer Cr(VI) follows the first order kinetics and has the activation energies of 76.6 and 41.5Â kJÂ mol-1, respectively. The properties of thermal unstablility and the high adsorption capacity of Li/Al LDH may lead to the development of an innovative technique for the removal of Cr(VI) from Cr(VI)-containing wastewater. That is, Li/Al LDH may be used as an effective adsorbent for the adsorption of Cr(VI) in an ambient environment. Following the adsorptive process, the adsorbed Cr(VI) may be released, using heated water to treat the Cr(VI)-containing Li/Al LDH particles. Through this hydrothermal treatment of the used adsorbent, Cr(VI) can be recovered and the solid product (gibbsite) can be recycled for further use."
565121,Hill et al. 2008,Hypersensitivity to chromium-induced DNA damage correlates with constitutive deregulation of upstream p53 kinases in p21-/- HCT116 colon cancer cells,"The cyclin-dependent kinase inhibitor p21CIP1/WAF1 is a key component in cell cycle control and apoptosis, directing an anti-apoptotic response following DNA damage. Chromium exposure resulted in a 500-1000 fold increase in apoptosis-induced cell death in p21-/- HCT116 cells compared to wild-type or p53-/- cells. p53 shRNA (or transient p53 siRNA) into p21-/- HCT116 cells reduced Cr(VI) sensitivity, suggesting the enhanced apoptosis in p21-/- cells is p53-dependent. Under non-DNA damage conditions, the p53 level in p21-/- cells was significantly higher than in wild-type cells, due to enhanced p53 phosphorylation and stabilization rather than elevated p53 transcription. Wild-type cells showed significant p53 protein induction upon DNA damage whereas p21-/- cells showed no p53 increase. p21-/- cells display the constitutive activation of upstream p53 kinases (ATM, DNA-PK, ATR, AKT and p38). 2D gel analysis revealed p53 patterns in p21-/- cells were distinct from those in wild-type cells before and after chromium exposure. Our results suggest that p21 has an important role in the cellular response to normal replicative stress and its absence leads to a ""chronic DNA damage"" state that primes the cell for p53-dependent apoptosis.","Hypersensitivity to chromium-induced DNA damage correlates with constitutive deregulation of upstream p53 kinases in p21-/- HCT116 colon cancer cells Abs: The cyclin-dependent kinase inhibitor p21CIP1/WAF1 is a key component in cell cycle control and apoptosis, directing an anti-apoptotic response following DNA damage. Chromium exposure resulted in a 500-1000 fold increase in apoptosis-induced cell death in p21-/- HCT116 cells compared to wild-type or p53-/- cells. p53 shRNA (or transient p53 siRNA) into p21-/- HCT116 cells reduced Cr(VI) sensitivity, suggesting the enhanced apoptosis in p21-/- cells is p53-dependent. Under non-DNA damage conditions, the p53 level in p21-/- cells was significantly higher than in wild-type cells, due to enhanced p53 phosphorylation and stabilization rather than elevated p53 transcription. Wild-type cells showed significant p53 protein induction upon DNA damage whereas p21-/- cells showed no p53 increase. p21-/- cells display the constitutive activation of upstream p53 kinases (ATM, DNA-PK, ATR, AKT and p38). 2D gel analysis revealed p53 patterns in p21-/- cells were distinct from those in wild-type cells before and after chromium exposure. Our results suggest that p21 has an important role in the cellular response to normal replicative stress and its absence leads to a ""chronic DNA damage"" state that primes the cell for p53-dependent apoptosis."
558111,Desai et al. 2008,Hexavalent chromate reductase activity in cytosolic fractions of Pseudomonas sp. G1DM21 isolated from Cr(VI) contaminated industrial landfill,"Hexavalent chromate reductase activity was localized and characterized in vitro in cytosolic fraction of a newly isolated Pseudomonas sp. G1DM21. The suspended culture of the bacterium reduced 99.7% of 500Â [mu]M Cr(VI) and 93.06% of 1000Â [mu]M Cr(VI) in 48Â h. The suspended culture repeatedly reduced 100Â [mu]M Cr(VI) within 6Â h up to four consecutive inputs. The permeabilized cells of the bacterium reduced 92% of 100Â [mu]M Cr(VI) within 6Â h. The cell-free extracts (CFE) reduced 90% of 100Â [mu]M Cr(VI) in 120Â min. The Km and Vmax determined for chromate reductase activity in the CFE were 175Â [mu]M Cr(VI) and 1.6Â [mu]moles/min/mg of protein, respectively, the Km and Vmax determined in the presence of 0.5Â mM NADH were 150Â [mu]M Cr(VI) and 2.0Â [mu]moles/min/mg of protein, respectively. Hexavalent chromate reductase activity was maximum at 30Â Â°C and pH 7.0. Relative molecular mass (Mr) of the native Cr(VI) reductase in the cytosolic fraction was estimated as 61.7Â kDa. The Cr(VI) reductase activity increased in the presence of metal ions like Cu2+, Mg2+, Na+ and electron donors like citrate, succinate, acetate and was significantly inhibited in the presence of metal ions like Hg2+, Ag+, Cd2+, disulfide reducers like 2-mercaptoethanol, while the respiratory inhibitors had a minute effect on the activity. Scanning probe atomic force microscopy (AFM) analysis indicates that exposure of Pseudomonas sp. G1DM21 to 1Â mM Cr(VI) for 24Â h, leads to an increase in cell length and height.","Hexavalent chromate reductase activity in cytosolic fractions of Pseudomonas sp. G1DM21 isolated from Cr(VI) contaminated industrial landfill Abs: Hexavalent chromate reductase activity was localized and characterized in vitro in cytosolic fraction of a newly isolated Pseudomonas sp. G1DM21. The suspended culture of the bacterium reduced 99.7% of 500Â [mu]M Cr(VI) and 93.06% of 1000Â [mu]M Cr(VI) in 48Â h. The suspended culture repeatedly reduced 100Â [mu]M Cr(VI) within 6Â h up to four consecutive inputs. The permeabilized cells of the bacterium reduced 92% of 100Â [mu]M Cr(VI) within 6Â h. The cell-free extracts (CFE) reduced 90% of 100Â [mu]M Cr(VI) in 120Â min. The Km and Vmax determined for chromate reductase activity in the CFE were 175Â [mu]M Cr(VI) and 1.6Â [mu]moles/min/mg of protein, respectively, the Km and Vmax determined in the presence of 0.5Â mM NADH were 150Â [mu]M Cr(VI) and 2.0Â [mu]moles/min/mg of protein, respectively. Hexavalent chromate reductase activity was maximum at 30Â Â°C and pH 7.0. Relative molecular mass (Mr) of the native Cr(VI) reductase in the cytosolic fraction was estimated as 61.7Â kDa. The Cr(VI) reductase activity increased in the presence of metal ions like Cu2+, Mg2+, Na+ and electron donors like citrate, succinate, acetate and was significantly inhibited in the presence of metal ions like Hg2+, Ag+, Cd2+, disulfide reducers like 2-mercaptoethanol, while the respiratory inhibitors had a minute effect on the activity. Scanning probe atomic force microscopy (AFM) analysis indicates that exposure of Pseudomonas sp. G1DM21 to 1Â mM Cr(VI) for 24Â h, leads to an increase in cell length and height."
553085,Bosisio et al. 2009,"Developmental toxicity, uptake and distribution of sodium chromate assayed by frog embryo teratogenesis assay-Xenopus (FETAX)","The embryotoxicity and teratogenicity of Cr(VI) on the survival and morphology of the anuran Xenopus laevis have been assessed by frog embryo teratogenesis assay-Xenopus(FETAX). The lethal median (LC50) and teratogenic median (TC50) concentration values of Cr(VI) were 890Â ÂµM and 260Â ÂµM, respectively. The calculated teratogenic index (TI) value was 3.42, suggesting that hexavalent chromium has a teratogenic potential. Malformations of embryos included lifting of the body, coiling of the tail and body oedema. Furthermore, the chromium salt caused significant growth retardation at 25Â ÂµM exposure concentrations. The use of radiolabelled 51Cr(VI) allowed the determination of the time course uptake of Cr in Xenopus exposed to concentrations ranging from 0.025 to 500Â ÂµM. The evaluation of its distribution into the body (head-abdomen-tail) was evaluated at different exposure times. Chromium is taken up at 24Â h by Xenopus embryos for all concentrations tested. At 48Â h post fertilization (stage of larva) the amount of Cr accumulated by the two-day-old larva ranged from 0.42 to 580Â pg mg-Â 1 wet weight at 0.025 and 500Â ÂµM respectively. These amounts were lower than those at 24Â h (2.77 to 11016Â pg mg-Â 1 wet weight embryo) reaching values of the same order of magnitude at 120Â h (five-days-old larva). Since at 48Â h Xenopus development leads to a swimming embryo, the observed uptake at 24Â h could be the result of the binding of Cr to jelly coat compounds surrounding the embryo body as confirmed by gel filtration experiments on 51Cr-jelly coat. The interaction of Cr with jelly coat is in agreement with the role of jelly coat in protecting the embryo against pathogen and chemical toxins to ensure fertilization. This work further supports the hypothesis that Cr contamination of surface waters could contribute to explain the reported worldwide depletion of frog population.","Developmental toxicity, uptake and distribution of sodium chromate assayed by frog embryo teratogenesis assay-Xenopus (FETAX) Abs: The embryotoxicity and teratogenicity of Cr(VI) on the survival and morphology of the anuran Xenopus laevis have been assessed by frog embryo teratogenesis assay-Xenopus(FETAX). The lethal median (LC50) and teratogenic median (TC50) concentration values of Cr(VI) were 890Â ÂµM and 260Â ÂµM, respectively. The calculated teratogenic index (TI) value was 3.42, suggesting that hexavalent chromium has a teratogenic potential. Malformations of embryos included lifting of the body, coiling of the tail and body oedema. Furthermore, the chromium salt caused significant growth retardation at 25Â ÂµM exposure concentrations. The use of radiolabelled 51Cr(VI) allowed the determination of the time course uptake of Cr in Xenopus exposed to concentrations ranging from 0.025 to 500Â ÂµM. The evaluation of its distribution into the body (head-abdomen-tail) was evaluated at different exposure times. Chromium is taken up at 24Â h by Xenopus embryos for all concentrations tested. At 48Â h post fertilization (stage of larva) the amount of Cr accumulated by the two-day-old larva ranged from 0.42 to 580Â pg mg-Â 1 wet weight at 0.025 and 500Â ÂµM respectively. These amounts were lower than those at 24Â h (2.77 to 11016Â pg mg-Â 1 wet weight embryo) reaching values of the same order of magnitude at 120Â h (five-days-old larva). Since at 48Â h Xenopus development leads to a swimming embryo, the observed uptake at 24Â h could be the result of the binding of Cr to jelly coat compounds surrounding the embryo body as confirmed by gel filtration experiments on 51Cr-jelly coat. The interaction of Cr with jelly coat is in agreement with the role of jelly coat in protecting the embryo against pathogen and chemical toxins to ensure fertilization. This work further supports the hypothesis that Cr contamination of surface waters could contribute to explain the reported worldwide depletion of frog population."
552905,Bonfranceschi et al. 2009,Study of the heavy metal phytoextraction capacity of two forage species growing in an hydroponic environment,"Sorghum and alfalfa are two important forage crops. We studied their capacity for accumulating heavy metals in hydroponic experiments. Cadmium, nickel (as divalent cations) and chromium (trivalent and hexavalent) were added individually to the nutrient solution in a range of concentrations from 1 to 80Â mg/l. Cr(III) was complexed with EDTA to increase its bioavailability. In alfalfa the increases in the concentration of Cr(III) and Cr(VI) favoured translocation of the metals to the upper parts of the plants, while with Ni(II) the level of translocated metal remained almost unchanged. In sorghum, both Cr(VI) and Ni(II) produced similar results to those in alfalfa, but increases in the concentrations of Cd(II) and Cr(III) in the solution lead to a higher accumulation of the metal at the root level. The concentrations referred to the dry biomass of alfalfa were 500Â mg/kg (aerial parts) and 1500Â mg/kg (roots) of Cr(III), simultaneously enhancing plant growth. Sorghum captured 500 and 1100Â mg/kg (in aerial parts) and 300 and 2000Â mg/kg (in roots) for Ni(II) and Cd(II) respectively, without significant damage to its biomass. The results show that alfalfa and sorghum can not only grow in the presence of high heavy metal concentration but also capture and translocate them to the aerial parts; because of these results special attention should be given to these crop plants for their possible use in phytoremediation of large contaminated areas but especially to avoid the possible introduction of the metals accumulated in aerial parts into the food chain when those plants grow in contaminated areas.","Study of the heavy metal phytoextraction capacity of two forage species growing in an hydroponic environment Abs: Sorghum and alfalfa are two important forage crops. We studied their capacity for accumulating heavy metals in hydroponic experiments. Cadmium, nickel (as divalent cations) and chromium (trivalent and hexavalent) were added individually to the nutrient solution in a range of concentrations from 1 to 80Â mg/l. Cr(III) was complexed with EDTA to increase its bioavailability. In alfalfa the increases in the concentration of Cr(III) and Cr(VI) favoured translocation of the metals to the upper parts of the plants, while with Ni(II) the level of translocated metal remained almost unchanged. In sorghum, both Cr(VI) and Ni(II) produced similar results to those in alfalfa, but increases in the concentrations of Cd(II) and Cr(III) in the solution lead to a higher accumulation of the metal at the root level. The concentrations referred to the dry biomass of alfalfa were 500Â mg/kg (aerial parts) and 1500Â mg/kg (roots) of Cr(III), simultaneously enhancing plant growth. Sorghum captured 500 and 1100Â mg/kg (in aerial parts) and 300 and 2000Â mg/kg (in roots) for Ni(II) and Cd(II) respectively, without significant damage to its biomass. The results show that alfalfa and sorghum can not only grow in the presence of high heavy metal concentration but also capture and translocate them to the aerial parts; because of these results special attention should be given to these crop plants for their possible use in phytoremediation of large contaminated areas but especially to avoid the possible introduction of the metals accumulated in aerial parts into the food chain when those plants grow in contaminated areas."
552864,Boloorchi et al. 2007,BrÃ»lure parÂ acide chromiqueÂ : prévention systématique deÂ laÂ toxicité systémique,"RÃ©sumÃ© Les brÃ»lures par acide chromique peuvent engendrer une toxicitÃ© systÃ©mique par absorption cutanÃ©e du chrome dÃ¨s les surfaces brÃ»lÃ©es supÃ©rieures Ã  1Â % de la surface corporelle totale (SCT). Pour illustrer la nÃ©cessitÃ© de prÃ©venir de maniÃ¨re systÃ©matique la toxicitÃ© par l'instauration d'un traitement spÃ©cifique devant toute exposition, nous vous prÃ©sentons le cas d'un patient ayant prÃ©sentÃ© une intoxication systÃ©mique au chrome dans la situation la moins sÃ©vÃ¨re de brÃ»lure chimique par acide chromiqueÂ : l'acide chromique Ã©tait fortement diluÃ© Ã  0,02Â %, la brÃ»lure Ã©tait du deuxiÃ¨me degrÃ© superficiel, thermique et chimique, sur l'avant-bras, et reprÃ©sentait 1Â % de la SCT. MalgrÃ© le traitement spÃ©cifique instaurÃ©, notre patient a eu un passage systÃ©mique du chrome, toutefois sans retentissement sur les fonctions rÃ©nale et hÃ©patique. Il a cicatrisÃ© en deux semaines et ses chromes sÃ©riques et urinaires se sont normalisÃ©s en trois semaines. Sans ce traitement spÃ©cifique prÃ©coce rÃ©alisÃ© dÃ¨s les urgences, quel aurait Ã©tÃ© le retentissement d'une intoxication systÃ©mique encore plus prononcÃ©eÂ ? Chromic acid burns can lead to systemic toxicity by cutaneous absorption of the chrome seen surfaces more than 1% of the total body surface area. In order to illustrate the necessity of anticipate systematically this toxicity by a specific treatment, we describe the case of a patient with systemic toxicity in the least severe situation of chromic acid burn: the chromic acid was diluted to 0,02%, the burn was superficial second degree, both thermic and chemical, on the forearm, and extended only to 1% of the total body surface area. In spite of the specific treatment, our patient had a blood transfer of the chrome, however without any consequences on the renal and hepatic functions. He cicatrised in 2Â weeks, and his blood and urinary chromium levels were normalised in 3Â weeks. Without this specific early treatment, what would have been the consequences of a systemic toxicity even more important?","BrÃ»lure parÂ acide chromiqueÂ : prévention systématique deÂ laÂ toxicité systémique Abs: RÃ©sumÃ© Les brÃ»lures par acide chromique peuvent engendrer une toxicitÃ© systÃ©mique par absorption cutanÃ©e du chrome dÃ¨s les surfaces brÃ»lÃ©es supÃ©rieures Ã  1Â % de la surface corporelle totale (SCT). Pour illustrer la nÃ©cessitÃ© de prÃ©venir de maniÃ¨re systÃ©matique la toxicitÃ© par l'instauration d'un traitement spÃ©cifique devant toute exposition, nous vous prÃ©sentons le cas d'un patient ayant prÃ©sentÃ© une intoxication systÃ©mique au chrome dans la situation la moins sÃ©vÃ¨re de brÃ»lure chimique par acide chromiqueÂ : l'acide chromique Ã©tait fortement diluÃ© Ã  0,02Â %, la brÃ»lure Ã©tait du deuxiÃ¨me degrÃ© superficiel, thermique et chimique, sur l'avant-bras, et reprÃ©sentait 1Â % de la SCT. MalgrÃ© le traitement spÃ©cifique instaurÃ©, notre patient a eu un passage systÃ©mique du chrome, toutefois sans retentissement sur les fonctions rÃ©nale et hÃ©patique. Il a cicatrisÃ© en deux semaines et ses chromes sÃ©riques et urinaires se sont normalisÃ©s en trois semaines. Sans ce traitement spÃ©cifique prÃ©coce rÃ©alisÃ© dÃ¨s les urgences, quel aurait Ã©tÃ© le retentissement d'une intoxication systÃ©mique encore plus prononcÃ©eÂ ? Chromic acid burns can lead to systemic toxicity by cutaneous absorption of the chrome seen surfaces more than 1% of the total body surface area. In order to illustrate the necessity of anticipate systematically this toxicity by a specific treatment, we describe the case of a patient with systemic toxicity in the least severe situation of chromic acid burn: the chromic acid was diluted to 0,02%, the burn was superficial second degree, both thermic and chemical, on the forearm, and extended only to 1% of the total body surface area. In spite of the specific treatment, our patient had a blood transfer of the chrome, however without any consequences on the renal and hepatic functions. He cicatrised in 2Â weeks, and his blood and urinary chromium levels were normalised in 3Â weeks. Without this specific early treatment, what would have been the consequences of a systemic toxicity even more important?"
549311,Akhtar et al. 2010,An economically viable method for the removal of selected divalent metal ions from aqueous solutions using activated rice husk,"Biosorption of divalent metal ions, i.e. Pb(II), Cd(II), Zn(II) and Cu(II) onto rice husk activated (RHA) is investigated over pH range (1-10) via batch adsorption technique. The chemical and thermal activation of rice husk with 0.1Â M HNO3 and 1Â M K2CO3 at 473Â K enhanced the removal efficiency of RHA (35Â Â±Â 2.1-99Â Â±Â 0.5%, 33Â Â±Â 1.2-97Â Â±Â 0.6%, 32Â Â±Â 1.3-96Â Â±Â 0.8% and 28Â Â±Â 1.8-95Â Â±Â 0.9% before and after treatment, respectively). The surface area analysis of RHA by BET (Brunauer, Emmett and Teller) nitrogen adsorption method provided pore area and average pore diameter to be 542Â Â±Â 2.3Â m2Â g-1 and 1076Â Â±Â 5.6Â nm respectively. SEM and FTIR analyses of RHA were carried out to determine the surface morphology and functional groups involved in metal binding mechanism, respectively. The adsorption equilibrium was well described by Freundlich, Langmuir and Dubinin-Radushkevish (D-R) isotherm models by employing (4.8-48, 8.9-89, 15.3-153 and 15.7-157)Â Ã?Â 10-5Â M solution concentrations of sorbates, respectively, at equilibrium time of 20Â min at pH 6 and onto 0.2Â g of sorbent. The kinetics of mass transfer and intra-particle diffusion for metal ions sorption onto RHA were studied with Lagergren and Morris-Weber kinetic models. The numerical values of thermodynamic parameters indicated the exothermic nature, spontaneity and feasibility of the sorption process. The desorption study of metal components from RHA surface was carried out with 0.1Â M HCl. The sorption mechanism developed illustrates the strong interactions of sorbates with the active sites of the sorbent coupled with efficient and environmentally clean exploitation of rice waste product.","An economically viable method for the removal of selected divalent metal ions from aqueous solutions using activated rice husk Abs: Biosorption of divalent metal ions, i.e. Pb(II), Cd(II), Zn(II) and Cu(II) onto rice husk activated (RHA) is investigated over pH range (1-10) via batch adsorption technique. The chemical and thermal activation of rice husk with 0.1Â M HNO3 and 1Â M K2CO3 at 473Â K enhanced the removal efficiency of RHA (35Â Â±Â 2.1-99Â Â±Â 0.5%, 33Â Â±Â 1.2-97Â Â±Â 0.6%, 32Â Â±Â 1.3-96Â Â±Â 0.8% and 28Â Â±Â 1.8-95Â Â±Â 0.9% before and after treatment, respectively). The surface area analysis of RHA by BET (Brunauer, Emmett and Teller) nitrogen adsorption method provided pore area and average pore diameter to be 542Â Â±Â 2.3Â m2Â g-1 and 1076Â Â±Â 5.6Â nm respectively. SEM and FTIR analyses of RHA were carried out to determine the surface morphology and functional groups involved in metal binding mechanism, respectively. The adsorption equilibrium was well described by Freundlich, Langmuir and Dubinin-Radushkevish (D-R) isotherm models by employing (4.8-48, 8.9-89, 15.3-153 and 15.7-157)Â Ã?Â 10-5Â M solution concentrations of sorbates, respectively, at equilibrium time of 20Â min at pH 6 and onto 0.2Â g of sorbent. The kinetics of mass transfer and intra-particle diffusion for metal ions sorption onto RHA were studied with Lagergren and Morris-Weber kinetic models. The numerical values of thermodynamic parameters indicated the exothermic nature, spontaneity and feasibility of the sorption process. The desorption study of metal components from RHA surface was carried out with 0.1Â M HCl. The sorption mechanism developed illustrates the strong interactions of sorbates with the active sites of the sorbent coupled with efficient and environmentally clean exploitation of rice waste product."
548629,Zahoor and  Rehman 2009,Isolation of Cr(VI) reducing bacteria from industrial effluents and their potential use in bioremediation of chromium containing wastewater,"The present study was aimed to assess the ability of Bacillus sp. JDM-2-1 and Staphylococcus capitis to reduce hexavalent chromium into its trivalent form. Bacillus sp. JDM-2-1 could tolerate Cr(VI) (4800 mu g/mL) and S. capitis could tolerate Cr(VI) (2800 mu g/mL). Both organisms were able to resist Cd super(2+) (50 mu g/mL), Cu super(2+) (200 mu g/mL), Pb super(2+) (800 mu g/mL), Hg super(2+) (50 mu g/mL) and Ni super(2+) (4000 mu g/mL). S. capitis resisted Zn super(2+) at 700 mu g/mL while Bacillus sp. JDM-2-1 only showed resistance up to 50 mu g/mL. Bacillus sp. JDM-2-1 and S. capitis showed optimum growth at pH 6 and 7, respectively, while both bacteria showed optimum growth at 37 degree C. Bacillus sp. JDM-2-1 and S. capitis could reduce 85% and 81% of hexavalent chromium from the medium after 96 h and were also capable of reducing hexavalent chromium 86% and 89%, respectively, from the industrial effluents after 144 h. Cell free extracts of Bacillus sp. JDM-2-1 and S. capitis showed reduction of 83% and 70% at concentration of 10 mu g Cr(VI)/mL, respectively. The presence of an induced protein having molecular weight around 25 kDa in the presence of chromium points out a possible role of this protein in chromium reduction. The bacterial isolates can be exploited for the bioremediation of hexavalent chromium containing wastes, since they seem to have a potential to reduce the toxic hexavalent form to its nontoxic trivalent form.","Isolation of Cr(VI) reducing bacteria from industrial effluents and their potential use in bioremediation of chromium containing wastewater Abs: The present study was aimed to assess the ability of Bacillus sp. JDM-2-1 and Staphylococcus capitis to reduce hexavalent chromium into its trivalent form. Bacillus sp. JDM-2-1 could tolerate Cr(VI) (4800 mu g/mL) and S. capitis could tolerate Cr(VI) (2800 mu g/mL). Both organisms were able to resist Cd super(2+) (50 mu g/mL), Cu super(2+) (200 mu g/mL), Pb super(2+) (800 mu g/mL), Hg super(2+) (50 mu g/mL) and Ni super(2+) (4000 mu g/mL). S. capitis resisted Zn super(2+) at 700 mu g/mL while Bacillus sp. JDM-2-1 only showed resistance up to 50 mu g/mL. Bacillus sp. JDM-2-1 and S. capitis showed optimum growth at pH 6 and 7, respectively, while both bacteria showed optimum growth at 37 degree C. Bacillus sp. JDM-2-1 and S. capitis could reduce 85% and 81% of hexavalent chromium from the medium after 96 h and were also capable of reducing hexavalent chromium 86% and 89%, respectively, from the industrial effluents after 144 h. Cell free extracts of Bacillus sp. JDM-2-1 and S. capitis showed reduction of 83% and 70% at concentration of 10 mu g Cr(VI)/mL, respectively. The presence of an induced protein having molecular weight around 25 kDa in the presence of chromium points out a possible role of this protein in chromium reduction. The bacterial isolates can be exploited for the bioremediation of hexavalent chromium containing wastes, since they seem to have a potential to reduce the toxic hexavalent form to its nontoxic trivalent form."
547876,Saeed et al. 2005,"Removal and recovery of lead( II) from single and multimetal (Cd, Cu, Ni, Zn) solutions by crop milling waste (black gram husk)","The study reports removal of heavy metals when present singly or in binary and ternary systems by the milling agrowaste of Cicer arientinum (chickpea var. black gram) as the biosorbent. The biosorbent removed heavy metal ions efficiently from aqueous solutions with the selectivity order of Pb > Cd > Zn > Cu > Ni. The biosorption of metal ions by black gram husk (BGH) increased as the initial metal concentration increased. Biosorption equilibrium was established within 30 min, which was well described by the Langmuir and Freundlich adsorption isotherms. The maximum amount of heavy metals (q sub(max)) adsorbed at equilibrium was 49.97, 39.99, 33.81, 25.73 and 19.56 mg/g BGH biomass for Pb, Cd, Zn, Cu and Ni, respectively. The biosorption capacities were found to be pH dependent and the maximum adsorption occurred at the solution pH 5. Efficiency of the biosorbent to remove Pb from binary and ternary solutions with Cd, Cu, Ni and Zn was the same level as it was when present singly. The presence of Pb in the binary and ternary solutions also did not significantly affect the sorption of other metals. Breakthrough curves for continuous removal of Pb from single, binary and ternary metal solutions are reported for inlet-effluent equilibrium. Complete desorption of Pb and other metals in single and multimetal solutions was achieved with 0.1 M HCl in both shake flask and fixed bed column studies. This is the first report of removal of the highly toxic Pb, Cd, and other heavy metals in binary and ternary systems based on the biosorption by an agrowaste. The potential of application for the treatment of solutions containing these heavy metals in multimetal solutions is indicated.","Removal and recovery of lead( II) from single and multimetal (Cd, Cu, Ni, Zn) solutions by crop milling waste (black gram husk) Abs: The study reports removal of heavy metals when present singly or in binary and ternary systems by the milling agrowaste of Cicer arientinum (chickpea var. black gram) as the biosorbent. The biosorbent removed heavy metal ions efficiently from aqueous solutions with the selectivity order of Pb > Cd > Zn > Cu > Ni. The biosorption of metal ions by black gram husk (BGH) increased as the initial metal concentration increased. Biosorption equilibrium was established within 30 min, which was well described by the Langmuir and Freundlich adsorption isotherms. The maximum amount of heavy metals (q sub(max)) adsorbed at equilibrium was 49.97, 39.99, 33.81, 25.73 and 19.56 mg/g BGH biomass for Pb, Cd, Zn, Cu and Ni, respectively. The biosorption capacities were found to be pH dependent and the maximum adsorption occurred at the solution pH 5. Efficiency of the biosorbent to remove Pb from binary and ternary solutions with Cd, Cu, Ni and Zn was the same level as it was when present singly. The presence of Pb in the binary and ternary solutions also did not significantly affect the sorption of other metals. Breakthrough curves for continuous removal of Pb from single, binary and ternary metal solutions are reported for inlet-effluent equilibrium. Complete desorption of Pb and other metals in single and multimetal solutions was achieved with 0.1 M HCl in both shake flask and fixed bed column studies. This is the first report of removal of the highly toxic Pb, Cd, and other heavy metals in binary and ternary systems based on the biosorption by an agrowaste. The potential of application for the treatment of solutions containing these heavy metals in multimetal solutions is indicated."
546663,Hua et al. 2009,The determination of hexavalent chromium (Cr super(6) super(+)) in electronic and electrical components and products to comply with RoHS regulations,"Toxicity of hexavalent chromium (Cr super(6) super(+)) was focused on with a publication of EU RoHS directive, a novel method to determine hexavalent chromium is developed. It is a combination of energy dispersion X-ray fluorescence spectrometry (EDXRF), spot test, alkali digestion and UV-vis spectrophotometric analysis. First, by EDXRF screening, the presence or absence of element Cr was established. Spot test was followed to identify the valent state of chromium because Cr super(6) super(+) and Cr super(3) super(+) normally coexist. After alkali digestion, Cr(VI) was separated without an undersired Cr(VI)-Cr(III) interconversions. With a color reagent (DPC) to chelated with Cr(VI), the solution was finally detected by a UV-vis spectrophotometer at a wavelength of 540nm which is the basis of analyzing Cr(VI) quantitatively. Some parameters affecting analyses were studied. It was found that when pH in the final solution was 2.0, the extraction time was 60min, the extraction temperature was 90 super(o)C, pH during the extraction process was 7.5-8.5, and a mixed buffer solution (0.5M K sub(2)HPO sub(4)/0.5M KH sub(2)PO sub(4)) was added up to 1ml, colorimetric reagent was added to 2ml, it is optimal for extraction. Under this condition, interferences from Fe super(3) super(+), Pb super(2) super(+), Ag super(+), etc., were overcome. It was also found that the curves are rectilinear in the range of 0-500 mu gl super(-) super(1), the correlation coefficient is up to 0.999924, and the recovery rates are more than 85%, the Cr(III)-DPCO complex can be kept stable for 24h with a relative humidity (RH) range of 60-90%, and a temperature range of 5-40 super(o)C. So it can be concluded that the proposed method has a good sensitivity and high precision. It is a more convincing and reliable method due to its relative standard deviation (R.S.D.) <1% after six replicate determinations of Cr(VI) in an Fe-Ni alloy sample.","The determination of hexavalent chromium (Cr super(6) super(+)) in electronic and electrical components and products to comply with RoHS regulations Abs: Toxicity of hexavalent chromium (Cr super(6) super(+)) was focused on with a publication of EU RoHS directive, a novel method to determine hexavalent chromium is developed. It is a combination of energy dispersion X-ray fluorescence spectrometry (EDXRF), spot test, alkali digestion and UV-vis spectrophotometric analysis. First, by EDXRF screening, the presence or absence of element Cr was established. Spot test was followed to identify the valent state of chromium because Cr super(6) super(+) and Cr super(3) super(+) normally coexist. After alkali digestion, Cr(VI) was separated without an undersired Cr(VI)-Cr(III) interconversions. With a color reagent (DPC) to chelated with Cr(VI), the solution was finally detected by a UV-vis spectrophotometer at a wavelength of 540nm which is the basis of analyzing Cr(VI) quantitatively. Some parameters affecting analyses were studied. It was found that when pH in the final solution was 2.0, the extraction time was 60min, the extraction temperature was 90 super(o)C, pH during the extraction process was 7.5-8.5, and a mixed buffer solution (0.5M K sub(2)HPO sub(4)/0.5M KH sub(2)PO sub(4)) was added up to 1ml, colorimetric reagent was added to 2ml, it is optimal for extraction. Under this condition, interferences from Fe super(3) super(+), Pb super(2) super(+), Ag super(+), etc., were overcome. It was also found that the curves are rectilinear in the range of 0-500 mu gl super(-) super(1), the correlation coefficient is up to 0.999924, and the recovery rates are more than 85%, the Cr(III)-DPCO complex can be kept stable for 24h with a relative humidity (RH) range of 60-90%, and a temperature range of 5-40 super(o)C. So it can be concluded that the proposed method has a good sensitivity and high precision. It is a more convincing and reliable method due to its relative standard deviation (R.S.D.) <1% after six replicate determinations of Cr(VI) in an Fe-Ni alloy sample."
546476,Goyal and  Srivastava 2009,Characterization of novel Zea mays based biomaterial designed for toxic metals biosorption,"Structural modifications onto Zea mays Cob powder, ZMCP lead to the formation of novel biomaterial with increased sorption efficiency and environmental stability for the abatement of Pb (II), Cd (II), Ni (II) and Cr (III) in single as well as multi-metal ion solutions. Synthetic strategy for strengthening the functional groups, COO super(-) responsible for binding of metal species has been applied using acetylation, succination and graft co-polymerization processes. The resultant novel biomaterial exhibits enhancement in sorption efficiency from 2 to 15% and stability in terms of regeneration cycles from 3 to 5, evidence to support biomaterial designed has been provided on the basis of SEM, FTIR and TGA. The findings open up new avenues in the modern Green Technology of water treatment using biosorbent-possessing potential for commercialization.","Characterization of novel Zea mays based biomaterial designed for toxic metals biosorption Abs: Structural modifications onto Zea mays Cob powder, ZMCP lead to the formation of novel biomaterial with increased sorption efficiency and environmental stability for the abatement of Pb (II), Cd (II), Ni (II) and Cr (III) in single as well as multi-metal ion solutions. Synthetic strategy for strengthening the functional groups, COO super(-) responsible for binding of metal species has been applied using acetylation, succination and graft co-polymerization processes. The resultant novel biomaterial exhibits enhancement in sorption efficiency from 2 to 15% and stability in terms of regeneration cycles from 3 to 5, evidence to support biomaterial designed has been provided on the basis of SEM, FTIR and TGA. The findings open up new avenues in the modern Green Technology of water treatment using biosorbent-possessing potential for commercialization."
545650,Barrera et al. 2006,Removal of chromium and toxic ions present in mine drainage by Ectodermis of Opuntia,"This work presents conditions for hexavalent and trivalent chromium removal from aqueous solutions using natural, protonated and thermally treated Ectodermis of Opuntia. A removal of 77% of Cr(VI) and 99% of Cr(III) can be achieved. The sorbent material is characterized using scanning electron microscopy, energy dispersive X-ray spectroscopy, infrared spectroscopy, thermogravimetric analysis, before and after the contact with the chromium containing aqueous media. The results obtained from the characterization techniques indicate that the metal ion remains on the surface of the sorbent material. The percentage removal is found to depend on the initial chromium concentration and pH. The Cr(VI) and Cr(III) uptake process is maximum at pH 4, using 0.1g of sorbent per liter of aqueous solution. The natural Ectodermis of Opuntia showed a chromium adsorption capacity that was adequately described by the Langmuir adsorption isotherm. Finally, an actual mine drainage sample that contained Cd, Cr, Cu, Fe Zn, Ni and Pb was tested under optimal conditions for chromium removal and Ectodermis of Opuntia was found to be a suitable sorbent material. The use of this waste material for the treatment of metal-containing aqueous solutions as well as mine drainage is effective and economical.","Removal of chromium and toxic ions present in mine drainage by Ectodermis of Opuntia Abs: This work presents conditions for hexavalent and trivalent chromium removal from aqueous solutions using natural, protonated and thermally treated Ectodermis of Opuntia. A removal of 77% of Cr(VI) and 99% of Cr(III) can be achieved. The sorbent material is characterized using scanning electron microscopy, energy dispersive X-ray spectroscopy, infrared spectroscopy, thermogravimetric analysis, before and after the contact with the chromium containing aqueous media. The results obtained from the characterization techniques indicate that the metal ion remains on the surface of the sorbent material. The percentage removal is found to depend on the initial chromium concentration and pH. The Cr(VI) and Cr(III) uptake process is maximum at pH 4, using 0.1g of sorbent per liter of aqueous solution. The natural Ectodermis of Opuntia showed a chromium adsorption capacity that was adequately described by the Langmuir adsorption isotherm. Finally, an actual mine drainage sample that contained Cd, Cr, Cu, Fe Zn, Ni and Pb was tested under optimal conditions for chromium removal and Ectodermis of Opuntia was found to be a suitable sorbent material. The use of this waste material for the treatment of metal-containing aqueous solutions as well as mine drainage is effective and economical."
540942,Zvinowanda et al. 2009,A novel adsorbent for heavy metal remediation in aqueous environments,"The objective of this study was to investigate the possibility of using maize tassel as an alternative adsorbent for the removal of chromium (VI) and cadmium (II) ions from aqueous solutions. The effect of pH, solution temperature, contact time, initial metal ion concentration and adsorbent dose on the adsorption of chromium (VI) and cadmium (II) by tassel was investigated using batch methods. Adsorption for both chromium (VI) and cadmium (II) was found to be highly pH dependent compared to the other parameters investigated. Obtained results gave an adsorption capacity of 79.1% for chromium (VI) at pH 2, exposure time of 1h at 25 degrees C. Maximum capacity of cadmium of 88% was obtained in the pH range of 5-6 at 25 degrees C after exposure time of 1 h. The adsorption capacities of tassel for both chromium (VI) and cadmium (II) were found to be comparable to those of other commercial adsorbents currently in use for the removal of heavy metals from aqueous wastes. These results have demonstrated the immense potential of maize tassel as an alternative adsorbent for toxic metal ions remediation in polluted water and wastewater.","A novel adsorbent for heavy metal remediation in aqueous environments Abs: The objective of this study was to investigate the possibility of using maize tassel as an alternative adsorbent for the removal of chromium (VI) and cadmium (II) ions from aqueous solutions. The effect of pH, solution temperature, contact time, initial metal ion concentration and adsorbent dose on the adsorption of chromium (VI) and cadmium (II) by tassel was investigated using batch methods. Adsorption for both chromium (VI) and cadmium (II) was found to be highly pH dependent compared to the other parameters investigated. Obtained results gave an adsorption capacity of 79.1% for chromium (VI) at pH 2, exposure time of 1h at 25 degrees C. Maximum capacity of cadmium of 88% was obtained in the pH range of 5-6 at 25 degrees C after exposure time of 1 h. The adsorption capacities of tassel for both chromium (VI) and cadmium (II) were found to be comparable to those of other commercial adsorbents currently in use for the removal of heavy metals from aqueous wastes. These results have demonstrated the immense potential of maize tassel as an alternative adsorbent for toxic metal ions remediation in polluted water and wastewater."
539002,Zawadzka et al. 2007,"Pyridine-2,6-bis(thiocarboxylic acid) produced by Pseudomonas stutzeri KC reduces chromium(VI) and precipitates mercury, cadmium, lead and arsenic","Interactions of the Pseudomonas stutzeri KC siderophore pyridine-2,6-bis(thiocarboxylic acid) (pdtc) with chromium(VI), mercury(II), cadmium(II), lead(II), and arsenic(III) are described. Pdtc was found to reduce Cr(VI) to Cr(III) in both bacterial cultures and in abiotic reactions with chemically synthesized pdtc. Cr(III) subsequently formed complexes with pdtc and pdtc hydrolysis products, and their presence was confirmed using electrospray ionization-mass spectrometry (ESI-MS). Cr(III):pdtc complexes were found to slowly release Cr(III) as chromium sulfide and possibly Cr(III) oxides. Pdtc also formed poorly soluble complexes with Hg, Cd, Pb, and As(III). Hydrolysis of those complexes led to the formation of their respective metal sulfides as confirmed by energy dispersive X-ray spectroscopy (EDS) elemental analysis. The pdtc-producing strain P. stutzeri KC showed higher tolerance to most of these metals as compared to a pdtc-negative mutant. A novel role of pdtc is postulated as its involvement in providing an extracellular pool of thiols that are used for redox processes in detoxification of the bacterial extracellular environment. These redox processes can be mediated by transition metal:pdtc complexes.","Pyridine-2,6-bis(thiocarboxylic acid) produced by Pseudomonas stutzeri KC reduces chromium(VI) and precipitates mercury, cadmium, lead and arsenic Abs: Interactions of the Pseudomonas stutzeri KC siderophore pyridine-2,6-bis(thiocarboxylic acid) (pdtc) with chromium(VI), mercury(II), cadmium(II), lead(II), and arsenic(III) are described. Pdtc was found to reduce Cr(VI) to Cr(III) in both bacterial cultures and in abiotic reactions with chemically synthesized pdtc. Cr(III) subsequently formed complexes with pdtc and pdtc hydrolysis products, and their presence was confirmed using electrospray ionization-mass spectrometry (ESI-MS). Cr(III):pdtc complexes were found to slowly release Cr(III) as chromium sulfide and possibly Cr(III) oxides. Pdtc also formed poorly soluble complexes with Hg, Cd, Pb, and As(III). Hydrolysis of those complexes led to the formation of their respective metal sulfides as confirmed by energy dispersive X-ray spectroscopy (EDS) elemental analysis. The pdtc-producing strain P. stutzeri KC showed higher tolerance to most of these metals as compared to a pdtc-negative mutant. A novel role of pdtc is postulated as its involvement in providing an extracellular pool of thiols that are used for redox processes in detoxification of the bacterial extracellular environment. These redox processes can be mediated by transition metal:pdtc complexes."
538564,Yu and  Gu 2008,The role of EDTA in phytoextraction of hexavalent and trivalent chromium by two willow trees,"Effects of the synthetic chelator ethylenediamine tetraacetate (EDTA) on uptake and internal translocation of hexavalent and trivalent chromium by plants were investigated. Two different concentrations of EDTA were studied for enhancing the uptake and translocation of Cr from the hydroponic solution spiked with K2CrO4 or CrCl3 maintained at 24.0 +/- 1 degrees C. Faster removal of Cr3+ than Cr6+ by hybrid willows (Salix matsudana Koidz x Salix alba L.) from the plant growth media was observed. Negligible effect of EDTA on the uptake of Cr6+ was found, but significant decrease of the Cr concentration in roots was measured. Although the translocation of Cr6+ within plant materials was detected in response to EDTA concentration, the amount of Cr6+ translocated to the lower stems was considerably small. EDTA in the nutrient media showed a negative effect on the uptake of Cr3+ by hybrid willows; the removal rates of Cr3+ were significantly decreased. Translocation of Cr3+ into the stems and leaves was undetectable, but roots were the exclusive sink for Cr3+ accumulation. Weeping willows (Salix babylonica L.) showed lower removal rates for both chemical forms of Cr than hybrid willows. Although EDTA had a minor effect on Cr6+ uptake by weeping willows, positive effect on Cr6+ translocation within plant materials was observed. It was also determined that EDTA in plant growth media significantly decreased the amount of Cr3+ taken up by plants, but significantly increased Cr3+ mobilization from roots to stems. Results indicated that EDTA was unable to increase the uptake of Cr6+ by both plant species, but translocation of Cr6+-EDTA within plant materials was possible. Addition of EDTA in the nutrient media showed a strong influence on the uptake and translocation of Cr3+ in both willows. Cr3+-EDTA in tissues of weeping willows was more mobile than that in hybrid willows. The information has important implications for the use of metal chelator in plant nutritional research.","The role of EDTA in phytoextraction of hexavalent and trivalent chromium by two willow trees Abs: Effects of the synthetic chelator ethylenediamine tetraacetate (EDTA) on uptake and internal translocation of hexavalent and trivalent chromium by plants were investigated. Two different concentrations of EDTA were studied for enhancing the uptake and translocation of Cr from the hydroponic solution spiked with K2CrO4 or CrCl3 maintained at 24.0 +/- 1 degrees C. Faster removal of Cr3+ than Cr6+ by hybrid willows (Salix matsudana Koidz x Salix alba L.) from the plant growth media was observed. Negligible effect of EDTA on the uptake of Cr6+ was found, but significant decrease of the Cr concentration in roots was measured. Although the translocation of Cr6+ within plant materials was detected in response to EDTA concentration, the amount of Cr6+ translocated to the lower stems was considerably small. EDTA in the nutrient media showed a negative effect on the uptake of Cr3+ by hybrid willows; the removal rates of Cr3+ were significantly decreased. Translocation of Cr3+ into the stems and leaves was undetectable, but roots were the exclusive sink for Cr3+ accumulation. Weeping willows (Salix babylonica L.) showed lower removal rates for both chemical forms of Cr than hybrid willows. Although EDTA had a minor effect on Cr6+ uptake by weeping willows, positive effect on Cr6+ translocation within plant materials was observed. It was also determined that EDTA in plant growth media significantly decreased the amount of Cr3+ taken up by plants, but significantly increased Cr3+ mobilization from roots to stems. Results indicated that EDTA was unable to increase the uptake of Cr6+ by both plant species, but translocation of Cr6+-EDTA within plant materials was possible. Addition of EDTA in the nutrient media showed a strong influence on the uptake and translocation of Cr3+ in both willows. Cr3+-EDTA in tissues of weeping willows was more mobile than that in hybrid willows. The information has important implications for the use of metal chelator in plant nutritional research."
538238,Yongpisanphop et al. 2005,Toxicity and accumulation of lead and chromium in Hydrocotyle umbellata,"The aquatic plant, Hydrocotyle umbellata, was studied for its toxicity and accumulation of lead (Pb) and chromium (Cr) in a synthetic solution. Plants were cultured in a modified Hoagland's nutrient solutions supplemented with 20, 40, 60, 80, and 100 mg Pb/l as lead nitrate [Pb(NO3)(2)] and 2, 4, 6, 8, and 10 mg Cr/l as potassium dichromate (K2Cr2O7). They were separately harvested after 3, 6, 9, and 12 days. Plants exposed to Pb and Cr showed significant decreases in the biomass productivity and total chlorophyll content when the exposure time and metal concentration were increased. The accumulation of Pb and Cr in the plants was significantly increased, but it was not linear with the exposure time and metal concentration. Both metals were accumulated higher in the roots than in the shoots. The bioconcentration factor of Pb was higher than that of Cr at the same exposure time, indicating a higher accumulation potential of Pb than Cr in H. umbellata. Toxicity symptoms of both metals showed a reduction in the production of new plantlets, withering of petioles, and change in color of roots from light green to dark brown. Pb caused leaf chlorosis, whereas Cr caused leaf necrosis. The toxicity symptoms increased when the exposure time and metal concentration were increased.","Toxicity and accumulation of lead and chromium in Hydrocotyle umbellata Abs: The aquatic plant, Hydrocotyle umbellata, was studied for its toxicity and accumulation of lead (Pb) and chromium (Cr) in a synthetic solution. Plants were cultured in a modified Hoagland's nutrient solutions supplemented with 20, 40, 60, 80, and 100 mg Pb/l as lead nitrate [Pb(NO3)(2)] and 2, 4, 6, 8, and 10 mg Cr/l as potassium dichromate (K2Cr2O7). They were separately harvested after 3, 6, 9, and 12 days. Plants exposed to Pb and Cr showed significant decreases in the biomass productivity and total chlorophyll content when the exposure time and metal concentration were increased. The accumulation of Pb and Cr in the plants was significantly increased, but it was not linear with the exposure time and metal concentration. Both metals were accumulated higher in the roots than in the shoots. The bioconcentration factor of Pb was higher than that of Cr at the same exposure time, indicating a higher accumulation potential of Pb than Cr in H. umbellata. Toxicity symptoms of both metals showed a reduction in the production of new plantlets, withering of petioles, and change in color of roots from light green to dark brown. Pb caused leaf chlorosis, whereas Cr caused leaf necrosis. The toxicity symptoms increased when the exposure time and metal concentration were increased."
536756,Xie et al. 2008,Deficient repair of particulate hexavalent chromium-induced DNA double strand breaks leads to neoplastic transformation,"Hexavalent chromium (Cr(VI)) is a potent respiratory toxicant and carcinogen. The most carcinogenic for tris of Cr(VI) are the particulate salts such as lead chromate, which deposit and persist in the respiratory tract after inhalation. We demonstrate here that particulate chromate induces DNA double strand breaks in human lung cells with 0.1, 0.5, and 1 mu g/cm(3) lead chromate inducing 1.5, 2, and 5 relative increases in the percent of DNA in the comet tail, respectively. These lesions are repaired within 24h and require Mre11 expression for their repair. Particulate chromate also caused Mre11 to co-localize with gamma-H2A.X and ATM. Failure to repair these breaks with Mre11-induced neoplastic transformation including loss of cell contact inhibition and anchorage-independent growth. A 5-day exposure to lead chromate induced loss of cell contact inhibition in a concentration-dependent manner with 0, 0.1, 0.5, and 1 mu g/cm(2) lead chromate inducing 1, 78, and 103 foci in 20 dishes, respectively. These data indicate that Mre11 is critical to repairing particulate Cr(VI)-induced double strand breaks and preventing Cr(VI)-induced neoplastic transformation. (C) 2007 Elsevier B.V. All rights reserved.","Deficient repair of particulate hexavalent chromium-induced DNA double strand breaks leads to neoplastic transformation Abs: Hexavalent chromium (Cr(VI)) is a potent respiratory toxicant and carcinogen. The most carcinogenic for tris of Cr(VI) are the particulate salts such as lead chromate, which deposit and persist in the respiratory tract after inhalation. We demonstrate here that particulate chromate induces DNA double strand breaks in human lung cells with 0.1, 0.5, and 1 mu g/cm(3) lead chromate inducing 1.5, 2, and 5 relative increases in the percent of DNA in the comet tail, respectively. These lesions are repaired within 24h and require Mre11 expression for their repair. Particulate chromate also caused Mre11 to co-localize with gamma-H2A.X and ATM. Failure to repair these breaks with Mre11-induced neoplastic transformation including loss of cell contact inhibition and anchorage-independent growth. A 5-day exposure to lead chromate induced loss of cell contact inhibition in a concentration-dependent manner with 0, 0.1, 0.5, and 1 mu g/cm(2) lead chromate inducing 1, 78, and 103 foci in 20 dishes, respectively. These data indicate that Mre11 is critical to repairing particulate Cr(VI)-induced double strand breaks and preventing Cr(VI)-induced neoplastic transformation. (C) 2007 Elsevier B.V. All rights reserved."
536754,Xie et al. 2009,Zinc chromate induces chromosome instability and DNA double strand breaks in human lung cells,"Hexavalent chromium Cr(VI) is a respiratory toxicant and carcinogen, with Solubility playing an important role in its carcinogenic potential. Zinc chromate, a water insoluble or 'particulate' Cr(VI) compound, has been shown to be carcinogenic in epidemiology studies and to induce tumors in experimental animals, but its genotoxicity is poorly understood. Our study shows that zinc chromate induced concentration-dependent increases in cytotoxicity, chromosome damage and DNA double strand breaks in human lung cells. In response to zinc chromate-induced breaks, MRE11 expression was increased and ATM and ATR were phosphorylated, indicating that the DNA double strand break repair system was initiated in the cells. In addition, our data show that zinc chromate-induced double strand breaks were only observed in the G2/M phase population, with no significant amount of double strand breaks observed in G1 and S phase cells. These data will aid in understanding the mechanisms of zinc chromate toxicity and carcinogenesis. (C) 2008 Elsevier Inc. All rights reserved.","Zinc chromate induces chromosome instability and DNA double strand breaks in human lung cells Abs: Hexavalent chromium Cr(VI) is a respiratory toxicant and carcinogen, with Solubility playing an important role in its carcinogenic potential. Zinc chromate, a water insoluble or 'particulate' Cr(VI) compound, has been shown to be carcinogenic in epidemiology studies and to induce tumors in experimental animals, but its genotoxicity is poorly understood. Our study shows that zinc chromate induced concentration-dependent increases in cytotoxicity, chromosome damage and DNA double strand breaks in human lung cells. In response to zinc chromate-induced breaks, MRE11 expression was increased and ATM and ATR were phosphorylated, indicating that the DNA double strand break repair system was initiated in the cells. In addition, our data show that zinc chromate-induced double strand breaks were only observed in the G2/M phase population, with no significant amount of double strand breaks observed in G1 and S phase cells. These data will aid in understanding the mechanisms of zinc chromate toxicity and carcinogenesis. (C) 2008 Elsevier Inc. All rights reserved."
536753,Xie et al. 2007,Neoplastic transformation of human bronchial cells by lead chromate particles,"Particulate hexavalent chromium(Cr(VI)) is a well-established human lung carcinogen with widespread exposure among people in occupational settings and the general public. However, no studies have examined the chromate-induced malignant transformation of human lung epithelial cells, its predominant target. Human papillomavirus-immortalized human bronchial epithelial (BEP2D) cells were used to better understand the mechanisms involved in human bronchial carcinogenesis induced by particulate chromate. We found that aneuploid cells increased in a concentration-dependent manner after chronic exposure to lead chromate. Moreover, chronic exposure to lead chromate induced BEP2D cell transformation. Transformed BEP2D cells developed through a series of sequential steps, including altered cell morphology, loss of cell contact inhibition and anchorage-independent growth. Specifically, a 5-day exposure to lead chromate induced foci formation with 0, 1, 5, and 10 mu g/cm(2) lead chromate inducing 0, 7, 3, and 15 foci in 10 dishes. Anchorage independence was observed in cell lines derived from these foci. These foci-derived cells also showed centrosome amplification and increases in aneuploid metaphases. Our study demonstrates that particulate Cr(VI) is able to transform human bronchial epithelial cells, and that chromosome instability may play an important role in particulate Cr(Vi)-induced neoplastic transformation.","Neoplastic transformation of human bronchial cells by lead chromate particles Abs: Particulate hexavalent chromium(Cr(VI)) is a well-established human lung carcinogen with widespread exposure among people in occupational settings and the general public. However, no studies have examined the chromate-induced malignant transformation of human lung epithelial cells, its predominant target. Human papillomavirus-immortalized human bronchial epithelial (BEP2D) cells were used to better understand the mechanisms involved in human bronchial carcinogenesis induced by particulate chromate. We found that aneuploid cells increased in a concentration-dependent manner after chronic exposure to lead chromate. Moreover, chronic exposure to lead chromate induced BEP2D cell transformation. Transformed BEP2D cells developed through a series of sequential steps, including altered cell morphology, loss of cell contact inhibition and anchorage-independent growth. Specifically, a 5-day exposure to lead chromate induced foci formation with 0, 1, 5, and 10 mu g/cm(2) lead chromate inducing 0, 7, 3, and 15 foci in 10 dishes. Anchorage independence was observed in cell lines derived from these foci. These foci-derived cells also showed centrosome amplification and increases in aneuploid metaphases. Our study demonstrates that particulate Cr(VI) is able to transform human bronchial epithelial cells, and that chromosome instability may play an important role in particulate Cr(Vi)-induced neoplastic transformation."
536476,Wu et al. 2009,Multiplexed assay panel of cytotoxicity in HK-2 cells for detection of renal proximal tubule injury potential of compounds,"Proximal tubules of the kidneys are one of the most common targets of nephrotoxic drugs and chemicals. Screens to predict nephrotoxic potential of compounds with insights to mechanisms of toxicity facilitate lead optimization, guide structure-activity relationships, minimize risks of clinical nephrotoxicity and therefore are valuable in the process of drug discovery. We developed and characterized an in vitro assay multiplexed to measure several endpoints of cytotoxicity using HK-2 cells. Assays for lactate dehydrogenase, cellular caspase 3/7 activation, resazurin dye reduction and Hoechst 33342 DNA staining were multiplexed to maximize the ability to detect cell injury. Assays were performed after 5- or 24-h incubations to further enhance the sensitivity of detection of toxicity. Individual assays were optimized for cell density, assay linearity and assay performance under multiplexed conditions. Inducers of apoptosis (stauro-sporine) and necrosis (perhexiline) were used to validate the mechanistic aspects of cell death. Nephrotoxic compounds (5-fluorouracil, gentamicin, cisplatin, acetaminophen, para-aminophenol, potassium dichromate, ibuprofen, doxorubicin, cyclosporine, citrinin, puromycin) were used to determine the potential of this method to detect proximal tubule toxicity of compounds. Overall, this cost-effective multiplexed platform is more sensitive than a single endpoint assay, provides mechanistic cues of toxicity and is amenable for higher throughput screening. (c) 2009 Elsevier Ltd. All rights reserved.","Multiplexed assay panel of cytotoxicity in HK-2 cells for detection of renal proximal tubule injury potential of compounds Abs: Proximal tubules of the kidneys are one of the most common targets of nephrotoxic drugs and chemicals. Screens to predict nephrotoxic potential of compounds with insights to mechanisms of toxicity facilitate lead optimization, guide structure-activity relationships, minimize risks of clinical nephrotoxicity and therefore are valuable in the process of drug discovery. We developed and characterized an in vitro assay multiplexed to measure several endpoints of cytotoxicity using HK-2 cells. Assays for lactate dehydrogenase, cellular caspase 3/7 activation, resazurin dye reduction and Hoechst 33342 DNA staining were multiplexed to maximize the ability to detect cell injury. Assays were performed after 5- or 24-h incubations to further enhance the sensitivity of detection of toxicity. Individual assays were optimized for cell density, assay linearity and assay performance under multiplexed conditions. Inducers of apoptosis (stauro-sporine) and necrosis (perhexiline) were used to validate the mechanistic aspects of cell death. Nephrotoxic compounds (5-fluorouracil, gentamicin, cisplatin, acetaminophen, para-aminophenol, potassium dichromate, ibuprofen, doxorubicin, cyclosporine, citrinin, puromycin) were used to determine the potential of this method to detect proximal tubule toxicity of compounds. Overall, this cost-effective multiplexed platform is more sensitive than a single endpoint assay, provides mechanistic cues of toxicity and is amenable for higher throughput screening. (c) 2009 Elsevier Ltd. All rights reserved."
535670,Wise et al. 2009,Particulate and soluble hexavalent chromium are cytotoxic and genotoxic to Steller sea lion lung cells,"Hexavalent chromium is an environmental contaminant. Within the environment, marine waters are a common site for hexavalent chromium deposition. We have recently reported significantly high levels of chromium in skin tissue from North Atlantic right whales, These findings demonstrate that marine species are being exposed to chromium. It is possible that such exposures may be playing a role in population declines evident among certain marine mammals, such as the Steller sea lion. We developed a Steller sea lion lung cell line from Steller sea lion lung tissue. Hexavalent chromium was cytotoxic to these primary lung fibroblasts as 1, 2.5, 5, 10 and 25 mu M sodium chromate induced 104, 99, 92, 58 and 11% relative survival, respectively. It was also genotoxic as 0, 1, 2.5, 5 and 10 mu M sodium chromate damaged chromosomes in 6,11,21,36, and 39% of metaphases and damaged 6,12,27,49 and 57 total aberrations in 100 metaphases, respectively. We also considered the toxicity of particulate hexavalent chromium, as it is the more potent carcinogen in humans. We found that 0.1, 0.5,1,5 and 10 mu g/cm(2) particulate chromate induced 95, 88, 91, 70, and 52% relative cell survival, respectively. These concentrations were genotoxic and damaged chromosomes in 9, 13, 18, and 23% of metaphases and induced 9, 15, 20 and 30 total aberrations per 100 metaphases, respectively. These data indicate that if sufficiently exposed, chromium may adversely affect the struggling Steller sea lion population. It would be prudent to investigate the effects chromium has in other Steller sea lion organs in order to derive a better understanding of how chromium in the marine environment may be affecting the declining Steller sea lion population. (C) 2008 Elsevier B.V. All rights reserved","Particulate and soluble hexavalent chromium are cytotoxic and genotoxic to Steller sea lion lung cells Abs: Hexavalent chromium is an environmental contaminant. Within the environment, marine waters are a common site for hexavalent chromium deposition. We have recently reported significantly high levels of chromium in skin tissue from North Atlantic right whales, These findings demonstrate that marine species are being exposed to chromium. It is possible that such exposures may be playing a role in population declines evident among certain marine mammals, such as the Steller sea lion. We developed a Steller sea lion lung cell line from Steller sea lion lung tissue. Hexavalent chromium was cytotoxic to these primary lung fibroblasts as 1, 2.5, 5, 10 and 25 mu M sodium chromate induced 104, 99, 92, 58 and 11% relative survival, respectively. It was also genotoxic as 0, 1, 2.5, 5 and 10 mu M sodium chromate damaged chromosomes in 6,11,21,36, and 39% of metaphases and damaged 6,12,27,49 and 57 total aberrations in 100 metaphases, respectively. We also considered the toxicity of particulate hexavalent chromium, as it is the more potent carcinogen in humans. We found that 0.1, 0.5,1,5 and 10 mu g/cm(2) particulate chromate induced 95, 88, 91, 70, and 52% relative cell survival, respectively. These concentrations were genotoxic and damaged chromosomes in 9, 13, 18, and 23% of metaphases and induced 9, 15, 20 and 30 total aberrations per 100 metaphases, respectively. These data indicate that if sufficiently exposed, chromium may adversely affect the struggling Steller sea lion population. It would be prudent to investigate the effects chromium has in other Steller sea lion organs in order to derive a better understanding of how chromium in the marine environment may be affecting the declining Steller sea lion population. (C) 2008 Elsevier B.V. All rights reserved"
535668,Wise et al. 2006,Particulate and soluble hexavalent chromium ate cytotoxic and genotoxic to human lung epithelial cells,"Particulate hexavalent chromium (Cr(VI)) is a well-established human lung carcinogen. It is currently a major public health concern, there is widespread exposure to it in occupational settings and to the general public. However, despite the potential widespread exposure and the fact that the lung is its target organ, few studies have considered the toxic effects of particulate Cr(VI) in human lung cells. Accordingly, we used-lead chromate as a model particulate Cr(VI) compound and determined its cytotoxicity and genotoxicity in cultured human bronchial epithelial cells, using BEP2D cells as a model cell line. We found that lead chromate induced concentration-dependent cytotoxicity in BEP2D cells after a 24 h exposure. Specifically, the relative survival was 78, 59, 53, 46 and 0% after exposure to 0.5, 1, 5, 10 and 50 mu g/cm(2) lead chromate, respectively. Similarly, the amount of chromosome damage increased with concentration after 24 h exposure to lead chromate. Specifically, 0.5, 1, 5 and 10 mu g/cm(2) damaged 10, 13, 20 and 28% of metaphase cells with the total amount of damage reaching 11, 15, 24 and 36 aberrations per 100 metaphases, respectively. Lead chromate (50 mu g/cm(2) lead chromate) induced profound cell cycle delay and no metaphases were found. In addition we investigated the effects of soluble hexavalent chromium, sodium chromate, in this cell line. We found that 1, 2.5, 5 and 10 mu M sodium chromate induced 66, 35, 0 and 0% relative survival, respectively. The amount of chromosome damage increased with concentration after 24 It exposure to sodium chromate. Specifically, 1, 2.5 and 5 mu M damaged 25, 34 and 41% of metaphase cells with the total amount of damage reaching 33, 59 and 70 aberrations per 100 metaphases, respectively. Ten micromolar sodium chromate induced profound cell cycle delay and no metaphases were found. Overall the data clearly indicate that hexavalent Cr(VI) is cytotoxic and genotoxic to human lung epithelial cells. (c) 2006 Elsevier B.V. All rights reserved.","Particulate and soluble hexavalent chromium ate cytotoxic and genotoxic to human lung epithelial cells Abs: Particulate hexavalent chromium (Cr(VI)) is a well-established human lung carcinogen. It is currently a major public health concern, there is widespread exposure to it in occupational settings and to the general public. However, despite the potential widespread exposure and the fact that the lung is its target organ, few studies have considered the toxic effects of particulate Cr(VI) in human lung cells. Accordingly, we used-lead chromate as a model particulate Cr(VI) compound and determined its cytotoxicity and genotoxicity in cultured human bronchial epithelial cells, using BEP2D cells as a model cell line. We found that lead chromate induced concentration-dependent cytotoxicity in BEP2D cells after a 24 h exposure. Specifically, the relative survival was 78, 59, 53, 46 and 0% after exposure to 0.5, 1, 5, 10 and 50 mu g/cm(2) lead chromate, respectively. Similarly, the amount of chromosome damage increased with concentration after 24 h exposure to lead chromate. Specifically, 0.5, 1, 5 and 10 mu g/cm(2) damaged 10, 13, 20 and 28% of metaphase cells with the total amount of damage reaching 11, 15, 24 and 36 aberrations per 100 metaphases, respectively. Lead chromate (50 mu g/cm(2) lead chromate) induced profound cell cycle delay and no metaphases were found. In addition we investigated the effects of soluble hexavalent chromium, sodium chromate, in this cell line. We found that 1, 2.5, 5 and 10 mu M sodium chromate induced 66, 35, 0 and 0% relative survival, respectively. The amount of chromosome damage increased with concentration after 24 It exposure to sodium chromate. Specifically, 1, 2.5 and 5 mu M damaged 25, 34 and 41% of metaphase cells with the total amount of damage reaching 33, 59 and 70 aberrations per 100 metaphases, respectively. Ten micromolar sodium chromate induced profound cell cycle delay and no metaphases were found. Overall the data clearly indicate that hexavalent Cr(VI) is cytotoxic and genotoxic to human lung epithelial cells. (c) 2006 Elsevier B.V. All rights reserved."
534728,Werner et al. 2007,Use of micro-XANES to speciate chromium in airborne fine particles in the Sacramento Valley,"While particulate matter (PM) in the atmosphere can lead to a wide array of negative health effects, the cause of toxicity is largely unknown. One aspect of PM that likely affects health is the chemical composition, in particular the transition metals within the particles. Chromium is one transition metal of interest due to its two major oxidation states, with Cr(III)being much less toxic compared to Cr(VI). Using microfocused X-ray absorption near edge structure (micro-XANES), we analyzed the Cr speciation in fine particles (diameters <= 2.5 mu m) collected at three sites in the Sacramento Valley of northern California. The microfocused X-ray beam enables us to look at very small areas on the filter with a resolution of typically 5-7 micrometers. With XANES we are able to not only distinguish between Cr(VI) and Cr(III), but also to identify different types of Cr(III) and more reduced Cr species. At all of our sampling sites the main Cr species were Cr(III), with Cr-(OH)(3) or a Cr-Fe, chromite-like, phase being the dominant species. Cr(VI)-containing particles were found only in the most urban-site. All three sites contained some reduced Cr species, either Cr(0) or Cr3C2, although these were minor components. This work demonstrates that micro-XANES can be used as a minimally invasive analytical tool to investigate the composition of ambient PM.","Use of micro-XANES to speciate chromium in airborne fine particles in the Sacramento Valley Abs: While particulate matter (PM) in the atmosphere can lead to a wide array of negative health effects, the cause of toxicity is largely unknown. One aspect of PM that likely affects health is the chemical composition, in particular the transition metals within the particles. Chromium is one transition metal of interest due to its two major oxidation states, with Cr(III)being much less toxic compared to Cr(VI). Using microfocused X-ray absorption near edge structure (micro-XANES), we analyzed the Cr speciation in fine particles (diameters <= 2.5 mu m) collected at three sites in the Sacramento Valley of northern California. The microfocused X-ray beam enables us to look at very small areas on the filter with a resolution of typically 5-7 micrometers. With XANES we are able to not only distinguish between Cr(VI) and Cr(III), but also to identify different types of Cr(III) and more reduced Cr species. At all of our sampling sites the main Cr species were Cr(III), with Cr-(OH)(3) or a Cr-Fe, chromite-like, phase being the dominant species. Cr(VI)-containing particles were found only in the most urban-site. All three sites contained some reduced Cr species, either Cr(0) or Cr3C2, although these were minor components. This work demonstrates that micro-XANES can be used as a minimally invasive analytical tool to investigate the composition of ambient PM."
534357,Wei et al. 2005,Molecular study of thermal immobilization of Chromium(VI) with clay,"Clay that contains kaolinite has been used extensively as a raw material for manufacturing of bricks and china at 900-1100 degrees C. This study used clay to stabilize the contaminant chromium(VI) [Cr(VI)] through a heating process at 500-1100 degrees C. X-ray absorption spectroscopic results indicated that the 500-900 degrees C heating process transformed hazardous Cr(VI) to nontoxic Cr(III); Cr2O3 was the species detected as most abundant. The 1100 degrees C heating process caused the formation of Cr2SiO5, which was not detected in the samples heated at 500-900 degrees C. Fourier transformed extended X-ray absorption fine structure spectra were fitted by use of WinXAS software. Phase shifts and backscatter(ing) amplitudes for specific atom pairs, based on the crystallographic data for CrO3 and Cr2O3, were theoretically calculated with the FEFF software. The processed XAS data show that the first shell coordination numbers were similar to each other as the temperature was increased from 500 to 900 degrees C and 1100 degrees C, implying that their Cr(III) crystallite size was relatively similar. The interatomic distance between the target center element and the first shell for the 500-1100 degrees C samples was 1.98 angstrom. The Debye-Waller factor for the 1100 degrees C sample was increased compared with the 500 and 900 degrees C samples and probably indicates the formation of Cr2SiO5.","Molecular study of thermal immobilization of Chromium(VI) with clay Abs: Clay that contains kaolinite has been used extensively as a raw material for manufacturing of bricks and china at 900-1100 degrees C. This study used clay to stabilize the contaminant chromium(VI) [Cr(VI)] through a heating process at 500-1100 degrees C. X-ray absorption spectroscopic results indicated that the 500-900 degrees C heating process transformed hazardous Cr(VI) to nontoxic Cr(III); Cr2O3 was the species detected as most abundant. The 1100 degrees C heating process caused the formation of Cr2SiO5, which was not detected in the samples heated at 500-900 degrees C. Fourier transformed extended X-ray absorption fine structure spectra were fitted by use of WinXAS software. Phase shifts and backscatter(ing) amplitudes for specific atom pairs, based on the crystallographic data for CrO3 and Cr2O3, were theoretically calculated with the FEFF software. The processed XAS data show that the first shell coordination numbers were similar to each other as the temperature was increased from 500 to 900 degrees C and 1100 degrees C, implying that their Cr(III) crystallite size was relatively similar. The interatomic distance between the target center element and the first shell for the 500-1100 degrees C samples was 1.98 angstrom. The Debye-Waller factor for the 1100 degrees C sample was increased compared with the 500 and 900 degrees C samples and probably indicates the formation of Cr2SiO5."
533819,Wani et al. 2007,"Chromium reduction, plant growth-promoting potentials, and metal solubilizatrion by Bacillus sp. isolated from alluvial soil","The plant growth-promoting potentials, production of siderophore and solubilization of insoluble phosphorus (P) and zinc and lead by the chromium (vi) -reducing Bacillus species, PSB 1, PSB 7, and PSB 10, was assessed both in the presence and absence of chromium under in vitro conditions. The Bacillus strains tolerated chromium up to the concentration of 500 (PSB1), 400 (PSB7), and 550 mu g ml(-1) (PSB10), respectively, on nutrient agar plates. Bacillus sp. PSB 10 reduced Cr (vi) by 87% at pH 7, which was followed by Bacillus sp. PSB 1 (83%) and PSB 7 (74%) in nutrient broth after 120 h of incubation. A concentration of 50 mu g ml(-1) of Cr (vi) was completely reduced by Bacillus sp. PSB 1 and PSB 10 (after 100 h) and PSB 7 (after 120 h). The Bacillus strains PSB 1, PSB 7, and PSB 10 produced 19.3, 17.7, and 17.4 mu g ml(-1) of indole acetic acid, respectively, in luria bertani broth at 100 mu g ml(-1) of tryptophan, which consistently decreased with an increase in chromium concentration. The Bacillus strains were positive for siderophore, HCN, and ammonia both in the absence and presence of chromium. The Bacillus strains solubilized 375 (PSB 1), 340 (PSB 7), and 379 (PSB 10) mu g ml(-1) P, respectively, in Pikovskaya broth devoid of chromium. In contrast, chromium at 150 mu g ml(-1) reduced the amount of P solubilized by 17 (PSB 1), 15 (PSB 7), and 9% (PSB 10) compared to control. The tested bacterial strains solubilized a considerable amount of zinc and lead in nutrient broth both in the absence and presence of chromium. Generally, the chromium reduction and the plant growth-promoting potentials of chromium-reducing Bacillus were strongly correlated at the tested concentration of chromium. The present observations demonstrated that the chromium-reducing, metal-solubilizing, and plant growth-promoting potentials of the Bacillus strains PSB1, PSB 7, and PSB10 were not adversely affected by the chromium application and, hence, may be applied for raising the productivity of crops under metal-contaminated soils.","Chromium reduction, plant growth-promoting potentials, and metal solubilizatrion by Bacillus sp. isolated from alluvial soil Abs: The plant growth-promoting potentials, production of siderophore and solubilization of insoluble phosphorus (P) and zinc and lead by the chromium (vi) -reducing Bacillus species, PSB 1, PSB 7, and PSB 10, was assessed both in the presence and absence of chromium under in vitro conditions. The Bacillus strains tolerated chromium up to the concentration of 500 (PSB1), 400 (PSB7), and 550 mu g ml(-1) (PSB10), respectively, on nutrient agar plates. Bacillus sp. PSB 10 reduced Cr (vi) by 87% at pH 7, which was followed by Bacillus sp. PSB 1 (83%) and PSB 7 (74%) in nutrient broth after 120 h of incubation. A concentration of 50 mu g ml(-1) of Cr (vi) was completely reduced by Bacillus sp. PSB 1 and PSB 10 (after 100 h) and PSB 7 (after 120 h). The Bacillus strains PSB 1, PSB 7, and PSB 10 produced 19.3, 17.7, and 17.4 mu g ml(-1) of indole acetic acid, respectively, in luria bertani broth at 100 mu g ml(-1) of tryptophan, which consistently decreased with an increase in chromium concentration. The Bacillus strains were positive for siderophore, HCN, and ammonia both in the absence and presence of chromium. The Bacillus strains solubilized 375 (PSB 1), 340 (PSB 7), and 379 (PSB 10) mu g ml(-1) P, respectively, in Pikovskaya broth devoid of chromium. In contrast, chromium at 150 mu g ml(-1) reduced the amount of P solubilized by 17 (PSB 1), 15 (PSB 7), and 9% (PSB 10) compared to control. The tested bacterial strains solubilized a considerable amount of zinc and lead in nutrient broth both in the absence and presence of chromium. Generally, the chromium reduction and the plant growth-promoting potentials of chromium-reducing Bacillus were strongly correlated at the tested concentration of chromium. The present observations demonstrated that the chromium-reducing, metal-solubilizing, and plant growth-promoting potentials of the Bacillus strains PSB1, PSB 7, and PSB10 were not adversely affected by the chromium application and, hence, may be applied for raising the productivity of crops under metal-contaminated soils."
530882,Van Lierde et al. 2005,Capillary electrophoresis hyphenated to inductively coupled plasma-sector field-mass spectrometry for the detection of chromium species after incubation of chromium in simulated sweat,"The presence of chromium in chromium-tanned leather represents a considerable health problem since it can lead to chronic allergic contact dermatitis. Apart from trivalent chromium (Cr(III)), which is used for tanning, leather often contains hexavalent chromium (Cr(VI)), resulting from the oxidation of Cr(III) during the tanning process. This study deals With the chromium compounds in simulated sweat when brought into contact with Cr(III) or Cr(VI) and with chromium-tanned leathers. A capillary electrophoresis (CE) method was developed, with inductively coupled plasma-sector field-mass spectrometry (ICP-SF-MS) for element-specific detection. Two different electrophoretic runs, applying once the positive and once the negative polarity mode, were necessary for the detection of positively and negatively charged chromium species. Although sometimes described in the literature, a pre-run derivatization of the chromium-species was not performed here to prevent species transformation. 50 mmol(.)L(-1) sodium phosphate at a pH of 2.5 was used as CE separation buffer and as make-up liquid for the CE-ICP-SF-MS interface. When applied to simulated sweat samples incubated with Cr(VI), this method showed that methionine is responsible for the reduction of Cr(VI) into Cr(III), which, at its turn, forms a complex with lactic acid. In the case of sweat plus Cr(III), the latter step was also seen. Applied to simulated sweat in contact with leather samples, the method developed showed the presence of the former species among a much more complex pattern.","Capillary electrophoresis hyphenated to inductively coupled plasma-sector field-mass spectrometry for the detection of chromium species after incubation of chromium in simulated sweat Abs: The presence of chromium in chromium-tanned leather represents a considerable health problem since it can lead to chronic allergic contact dermatitis. Apart from trivalent chromium (Cr(III)), which is used for tanning, leather often contains hexavalent chromium (Cr(VI)), resulting from the oxidation of Cr(III) during the tanning process. This study deals With the chromium compounds in simulated sweat when brought into contact with Cr(III) or Cr(VI) and with chromium-tanned leathers. A capillary electrophoresis (CE) method was developed, with inductively coupled plasma-sector field-mass spectrometry (ICP-SF-MS) for element-specific detection. Two different electrophoretic runs, applying once the positive and once the negative polarity mode, were necessary for the detection of positively and negatively charged chromium species. Although sometimes described in the literature, a pre-run derivatization of the chromium-species was not performed here to prevent species transformation. 50 mmol(.)L(-1) sodium phosphate at a pH of 2.5 was used as CE separation buffer and as make-up liquid for the CE-ICP-SF-MS interface. When applied to simulated sweat samples incubated with Cr(VI), this method showed that methionine is responsible for the reduction of Cr(VI) into Cr(III), which, at its turn, forms a complex with lactic acid. In the case of sweat plus Cr(III), the latter step was also seen. Applied to simulated sweat in contact with leather samples, the method developed showed the presence of the former species among a much more complex pattern."
530081,Urbano et al. 2008,"Hexavalent chromium exposure, genomic instability and lung cancer","World-wide, several million workers experience occupational exposure to different hexavalent chromium [Cr(VI)] compounds (chromates) which have long been recognized as human respiratory tract carcinogens through chronic exposure. Although the majority of lung cancers were found among Cr(VI)-exposed workers who smoked, smoking does not affect chromium accumulation in the lung and chromate exposure was clearly established as an independent risk factor for lung cancer. Compatible with the smoking-unrelated origin of the majority of chromate malignancies are the findings that the molecular features of chromate- and smoking-associated cancers are very different and that the location of chromate lung tumors, i.e. the bronchial bifurcations, corresponds to the sites of chromium accumulation in ex-chromate workers. More recent studies also revealed that environmental exposure to particulate Cr(VI) compounds is increasing due to chromium-containing dusts generated from industrial waste disposal, portland cement, concrete pavement, milling, demolition, cigarette smoke and fuel combustion. Experimentally, it has been demonstrated that Cr(VI) compounds can neoplastically transform cells in culture. They are also genotoxic and can induce a wide spectrum of DNA damage, gene mutations, sister chromatid exchanges and chromosomal aberrations. Albeit extensive information and studies on Cr(VI)-induced effects, the mechanisms mediating Cr(VI)-induced toxicity and carcinogenicity are still poorly understood. This happens mostly due to the use, in a vast majority of the studies, of inadequate model systems and exposure regimens, as well as to the restricted access to lung tumor tissues from Cr(VI)-exposed workers, critical for the identification of consistent cellular and molecular changes. Consequently, additional studies using adequate model systems and exposure regimens mimicking occupational exposure conditions will have to be performed in order to understand the signalling mechanisms involved in the cellular response to Cr(VI), as well as the role of genomic instability and of specific DNA repair pathways in the development of this pathology. Knowledge of these pertinent issues will be a step forward for the discovery of biomarkers of malignant transformation that might lead to new treatment approaches or new ways to prevent this particular subtype of lung cancer. This review will discuss several aspects underlying Cr(VI)-induced carcinogenicity. However, particular emphasis will be given to the recently identified roles of Cr(VI)-induced DNA lesions, particularly single- and double-strand breaks, on genomic instability, one of the hallmarks of lung cancer.","Hexavalent chromium exposure, genomic instability and lung cancer Abs: World-wide, several million workers experience occupational exposure to different hexavalent chromium [Cr(VI)] compounds (chromates) which have long been recognized as human respiratory tract carcinogens through chronic exposure. Although the majority of lung cancers were found among Cr(VI)-exposed workers who smoked, smoking does not affect chromium accumulation in the lung and chromate exposure was clearly established as an independent risk factor for lung cancer. Compatible with the smoking-unrelated origin of the majority of chromate malignancies are the findings that the molecular features of chromate- and smoking-associated cancers are very different and that the location of chromate lung tumors, i.e. the bronchial bifurcations, corresponds to the sites of chromium accumulation in ex-chromate workers. More recent studies also revealed that environmental exposure to particulate Cr(VI) compounds is increasing due to chromium-containing dusts generated from industrial waste disposal, portland cement, concrete pavement, milling, demolition, cigarette smoke and fuel combustion. Experimentally, it has been demonstrated that Cr(VI) compounds can neoplastically transform cells in culture. They are also genotoxic and can induce a wide spectrum of DNA damage, gene mutations, sister chromatid exchanges and chromosomal aberrations. Albeit extensive information and studies on Cr(VI)-induced effects, the mechanisms mediating Cr(VI)-induced toxicity and carcinogenicity are still poorly understood. This happens mostly due to the use, in a vast majority of the studies, of inadequate model systems and exposure regimens, as well as to the restricted access to lung tumor tissues from Cr(VI)-exposed workers, critical for the identification of consistent cellular and molecular changes. Consequently, additional studies using adequate model systems and exposure regimens mimicking occupational exposure conditions will have to be performed in order to understand the signalling mechanisms involved in the cellular response to Cr(VI), as well as the role of genomic instability and of specific DNA repair pathways in the development of this pathology. Knowledge of these pertinent issues will be a step forward for the discovery of biomarkers of malignant transformation that might lead to new treatment approaches or new ways to prevent this particular subtype of lung cancer. This review will discuss several aspects underlying Cr(VI)-induced carcinogenicity. However, particular emphasis will be given to the recently identified roles of Cr(VI)-induced DNA lesions, particularly single- and double-strand breaks, on genomic instability, one of the hallmarks of lung cancer."
530058,Upreti et al. 2005,A comparative study on rat intestinal epithelial cells and resident gut bacteria: (I) - Effect of hexavalent chromium,"Toxicants including heavy metals reaching the intestine following ingestion through food and water primarily interact with an ecosystem of eukaryotic and prokaryotic cells. Gut bacteria having a dynamic interrelationship with intestinal epithelial cells are known to play important and specific metabolic, trophic,and protective functions. The present study was undertaken to compare the effects of hexavalent chromium on rat intestinal epithelial cells and the resident gut bacteria following in vitro and in vivo exposures. The survival rate and viability pattern of two types of cells were comparable. Under in vitro conditions, the gut bacteria were quick to reduce Cr (VI) in early time periods, while, at 30 h time, both types of cells showed similar capacity for the reduction of Cr (VI). Chromium intoxication (10 ppm of Cr (VI) in drinking water for 10 weeks) caused significant decrease in membrane alkaline phosphatase and Ca2+-Mg2+-ATPase activities of intestinal epithelial cells as well as of three gut bacteria viz. Escherichia coli, Pseudomonas sp, and Lactobacillus sp. Major structural membrane constituents like carbohydrates and phospholipids also showed significant decline in both types of cells. These findings indicate that 10 ppm and higher Cr concentrations may cause toxic insult, resulting in impaired intestinal functional efficacy. It also implies that the gut bacteria can be used at least for preliminary screening of heavy metals gastrointestinal toxicity.","A comparative study on rat intestinal epithelial cells and resident gut bacteria: (I) - Effect of hexavalent chromium Abs: Toxicants including heavy metals reaching the intestine following ingestion through food and water primarily interact with an ecosystem of eukaryotic and prokaryotic cells. Gut bacteria having a dynamic interrelationship with intestinal epithelial cells are known to play important and specific metabolic, trophic,and protective functions. The present study was undertaken to compare the effects of hexavalent chromium on rat intestinal epithelial cells and the resident gut bacteria following in vitro and in vivo exposures. The survival rate and viability pattern of two types of cells were comparable. Under in vitro conditions, the gut bacteria were quick to reduce Cr (VI) in early time periods, while, at 30 h time, both types of cells showed similar capacity for the reduction of Cr (VI). Chromium intoxication (10 ppm of Cr (VI) in drinking water for 10 weeks) caused significant decrease in membrane alkaline phosphatase and Ca2+-Mg2+-ATPase activities of intestinal epithelial cells as well as of three gut bacteria viz. Escherichia coli, Pseudomonas sp, and Lactobacillus sp. Major structural membrane constituents like carbohydrates and phospholipids also showed significant decline in both types of cells. These findings indicate that 10 ppm and higher Cr concentrations may cause toxic insult, resulting in impaired intestinal functional efficacy. It also implies that the gut bacteria can be used at least for preliminary screening of heavy metals gastrointestinal toxicity."
529946,Ulucinar and  Onar 2005,Effect of organic Cr(III) complexes on chromium speciation,"Chromium speciation in the presence of organic chromium(III) complexes was investigated using solid-phase extraction. The adsorptions of Cr(VI) and Cr(III) on alumina and pumice powder were studied. Maximum sorption of Cr(VI) was obtained by alumina (90.22%), while Cr(III) was highly adsorbed onto pumice powder (86.65%). This result shows that pumice may be a new and promising adsorbent for Cr(Ill). The experimental equilibrium data for Cr(VI) adsorption onto alumina and Cr(III) sorption onto pumice were analysed using Langmuir and Freundlich isotherms. The separation and adsorption of Cr(VI), Cr(Ill) and five organic chromium(III) complexes onto pumice and alumina at different pH values were evaluated. Ethylenediaminetetraacetate (EDTA), oxalate, citrate, glycine, alanine and 8-hydroxyqinoline were used as ligands. Sorption of alanine and ethylenediaminetetraacetate complexes was higher onto alumina than pumice at pH > 3. The enhancement of adsorption of chromium(III) complexes onto pumice was achieved by surface modification of pumice using a surfactant, namely hexadecyltrimethylammoniumbromur (HDTMA). The presence of surfactant enhanced the adsorption of Cr(III) citrate, oxalate, glycine and 8-hydroxyquinoline complexes onto pumice. However, the adsorption of EDTA and alanine complexes decreased, with ratio of 13.40% and 4.00% respectively. Here we demonstrate that chromium speciation methods depending on adsorption onto various adsorbents including alumina may lead erroneous results. Analytical measurements were performed by flame AAS, data were obtained by standard addition method.","Effect of organic Cr(III) complexes on chromium speciation Abs: Chromium speciation in the presence of organic chromium(III) complexes was investigated using solid-phase extraction. The adsorptions of Cr(VI) and Cr(III) on alumina and pumice powder were studied. Maximum sorption of Cr(VI) was obtained by alumina (90.22%), while Cr(III) was highly adsorbed onto pumice powder (86.65%). This result shows that pumice may be a new and promising adsorbent for Cr(Ill). The experimental equilibrium data for Cr(VI) adsorption onto alumina and Cr(III) sorption onto pumice were analysed using Langmuir and Freundlich isotherms. The separation and adsorption of Cr(VI), Cr(Ill) and five organic chromium(III) complexes onto pumice and alumina at different pH values were evaluated. Ethylenediaminetetraacetate (EDTA), oxalate, citrate, glycine, alanine and 8-hydroxyqinoline were used as ligands. Sorption of alanine and ethylenediaminetetraacetate complexes was higher onto alumina than pumice at pH > 3. The enhancement of adsorption of chromium(III) complexes onto pumice was achieved by surface modification of pumice using a surfactant, namely hexadecyltrimethylammoniumbromur (HDTMA). The presence of surfactant enhanced the adsorption of Cr(III) citrate, oxalate, glycine and 8-hydroxyquinoline complexes onto pumice. However, the adsorption of EDTA and alanine complexes decreased, with ratio of 13.40% and 4.00% respectively. Here we demonstrate that chromium speciation methods depending on adsorption onto various adsorbents including alumina may lead erroneous results. Analytical measurements were performed by flame AAS, data were obtained by standard addition method."
529445,Tudor et al. 2006,Seashells: Detoxifying agents for metal-contaminated waters,"Effective treatments of industrial waste streams and toxic spills containing heavy metals depend on the rapid removal of high concentrations of metal ions. Here we describe such a method using minimally-processed waste mollusk and crustacean exoskeletons. The process of metal extraction and immobilization was studied using atomic absorption, SEM/EDAX, and x-ray diffraction to investigate both solution and mineral phases. Compared to calcium carbonates of geologic origin, biomineralized shell materials exhibit extremely rapid sequestration of metal ions: a 10,000 mg L-1 Pb solution for example, can be reduced to less than about 0.5 mg L-1 in five minutes using comminuted shell of clam (M. mercenaria), while at higher initial concentrations, both clam and oyster (C. virginica) shell can extract almost twice their weight of Pb. The uptake mechanism involves the exchange of Ca for Pb in the inorganic fraction of the shell structure. Results highlight the importance of both surface area and the presence of the organic matrix of biominerals in determining the rate and quantity of metal ions abstracted, and the uniquely coherent residues produced in the process.","Seashells: Detoxifying agents for metal-contaminated waters Abs: Effective treatments of industrial waste streams and toxic spills containing heavy metals depend on the rapid removal of high concentrations of metal ions. Here we describe such a method using minimally-processed waste mollusk and crustacean exoskeletons. The process of metal extraction and immobilization was studied using atomic absorption, SEM/EDAX, and x-ray diffraction to investigate both solution and mineral phases. Compared to calcium carbonates of geologic origin, biomineralized shell materials exhibit extremely rapid sequestration of metal ions: a 10,000 mg L-1 Pb solution for example, can be reduced to less than about 0.5 mg L-1 in five minutes using comminuted shell of clam (M. mercenaria), while at higher initial concentrations, both clam and oyster (C. virginica) shell can extract almost twice their weight of Pb. The uptake mechanism involves the exchange of Ca for Pb in the inorganic fraction of the shell structure. Results highlight the importance of both surface area and the presence of the organic matrix of biominerals in determining the rate and quantity of metal ions abstracted, and the uniquely coherent residues produced in the process."
527170,Taseli et al. 2008,Influence of nickel (II) and chromium (VI) on the laboratory scale rotating biological contactor,"High concentration of heavy metals is toxic for most microorganisms and cause strict damage in wastewater treatment operations and often a physico-chemical pretreatment prior to biological treatment is considered necessary. However, in this study it has been shown that biological systems can adapt to Ni (II) and Cr (VI) when their concentration is below 10 and 20 mg/L, respectively. The aim of this study was to evaluate the effect of Ni (II) and Cr (VI) on the lab-scale rotating biological contactor process. It was found that, addition of Ni (II) up to 10 mg/L did not reduce the chemical oxygen demand removal efficiency and on the contrary concentrations below 10 mg/L improved the performance. The influent Ni (II) concentration of 1 mg/L was the concentration where the treatment efficiency produced a maximum COD removal of 86.5%. Moreover, Ni (II) concentration above 10 mg/L was relatively toxic to the system and produced lower treatment efficiencies than the baseline study without Ni (II). Turbidity and suspended solids removals were not stimulated to a great extent with nickel. Addition of Ni (II) did not seem to affect the pH of the system during treatment. The dissolved oxygen concentration did not drop below 4 mg/L at all concentrations of Ni (II) indicating aerobic conditions prevailed in the system. Experiments conducted with Cr (VI) revealed that addition of Cr (VI) up to 20 mg/L did not reduce the COD removal efficiency and on the contrary concentrations below 20 mg/L improved the performance. The influent Cr (VI) concentration of 1 mg/L was the concentration where the treatment efficiency produced a maximum COD removal of 88%. Turbidity and SS removals were more efficient at 5 mg/L Cr (VI) concentration, rather than 1 mg/L, which lead to the conclusion that 5 mg/L Cr (VI) concentration is the optimum concentration, in terms of COD, turbidity and SS removals. Similar with Ni (II) experiments, addition of Cr (VI) did not significantly affect the pH value of the effluent. The DO concentration remained above 5 mg/L.","Influence of nickel (II) and chromium (VI) on the laboratory scale rotating biological contactor Abs: High concentration of heavy metals is toxic for most microorganisms and cause strict damage in wastewater treatment operations and often a physico-chemical pretreatment prior to biological treatment is considered necessary. However, in this study it has been shown that biological systems can adapt to Ni (II) and Cr (VI) when their concentration is below 10 and 20 mg/L, respectively. The aim of this study was to evaluate the effect of Ni (II) and Cr (VI) on the lab-scale rotating biological contactor process. It was found that, addition of Ni (II) up to 10 mg/L did not reduce the chemical oxygen demand removal efficiency and on the contrary concentrations below 10 mg/L improved the performance. The influent Ni (II) concentration of 1 mg/L was the concentration where the treatment efficiency produced a maximum COD removal of 86.5%. Moreover, Ni (II) concentration above 10 mg/L was relatively toxic to the system and produced lower treatment efficiencies than the baseline study without Ni (II). Turbidity and suspended solids removals were not stimulated to a great extent with nickel. Addition of Ni (II) did not seem to affect the pH of the system during treatment. The dissolved oxygen concentration did not drop below 4 mg/L at all concentrations of Ni (II) indicating aerobic conditions prevailed in the system. Experiments conducted with Cr (VI) revealed that addition of Cr (VI) up to 20 mg/L did not reduce the COD removal efficiency and on the contrary concentrations below 20 mg/L improved the performance. The influent Cr (VI) concentration of 1 mg/L was the concentration where the treatment efficiency produced a maximum COD removal of 88%. Turbidity and SS removals were more efficient at 5 mg/L Cr (VI) concentration, rather than 1 mg/L, which lead to the conclusion that 5 mg/L Cr (VI) concentration is the optimum concentration, in terms of COD, turbidity and SS removals. Similar with Ni (II) experiments, addition of Cr (VI) did not significantly affect the pH value of the effluent. The DO concentration remained above 5 mg/L."
525936,Suzuki and  Mcdermot 2006,Infrared spectra of US automobile original finishes. VII. Extended range FT-IR and XRF analyses of inorganic pigments in situ-Nickel Titanate and Chrome Titanate,"The identification, analysis, and occurrence in U.S. automobile original finishes (1974-1989) of Nickel Titanate (yellow) and Chrome Titanate (yellow-orange) are described in this report. The titanate pigments are based on the rutile (titanium dioxide) structure and there are only minor differences between the infrared absorptions of rutile and the titanates. Titanate pigment absorptions in paint spectra can thus be easily mistaken for those of rutile. Each of the titanates, however, contains two elements in addition to titanium that can serve to distinguish them using elemental analyses. Fourier transform infrared (4000-220 cm(-1)) and X-ray fluorescence instruments were used in combination for the in situ analysis of the titanates. In addition to titanium, nickel, and antimony, the three main detectable elements comprising Nickel Titanate, all of the commercial products of this pigment that were examined also contained impurities of zirconium, niobium, and usually lead. These elements were also detected in most of the monocoats in which Nickel Titanate was identified, as well as in the Chrome Titanate pigments, and the zirconium to niobium ratio was found to exhibit a wide variation. Nickel Titanate is a relatively common pigment that was identified in nearly three dozen U.S. automobile yellow nonmetallic monocoats (1974-1989), while Chrome Titanate appears to have been used in only a few yellow and orange nonmetallic monocoats. The use of the titanate pigments likely increased after this time period as they were replacements for lead chromate pigments (last used in a U.S. automobile original finish in the early 1990s), and are more amenable for use in basecoat/clearcoat finishes than in monocoats. Minor distortions of the infrared absorptions of rutile, anatase, and the titanates obtained using accessories with diamond windows were noted, and their origins are discussed.","Infrared spectra of US automobile original finishes. VII. Extended range FT-IR and XRF analyses of inorganic pigments in situ-Nickel Titanate and Chrome Titanate Abs: The identification, analysis, and occurrence in U.S. automobile original finishes (1974-1989) of Nickel Titanate (yellow) and Chrome Titanate (yellow-orange) are described in this report. The titanate pigments are based on the rutile (titanium dioxide) structure and there are only minor differences between the infrared absorptions of rutile and the titanates. Titanate pigment absorptions in paint spectra can thus be easily mistaken for those of rutile. Each of the titanates, however, contains two elements in addition to titanium that can serve to distinguish them using elemental analyses. Fourier transform infrared (4000-220 cm(-1)) and X-ray fluorescence instruments were used in combination for the in situ analysis of the titanates. In addition to titanium, nickel, and antimony, the three main detectable elements comprising Nickel Titanate, all of the commercial products of this pigment that were examined also contained impurities of zirconium, niobium, and usually lead. These elements were also detected in most of the monocoats in which Nickel Titanate was identified, as well as in the Chrome Titanate pigments, and the zirconium to niobium ratio was found to exhibit a wide variation. Nickel Titanate is a relatively common pigment that was identified in nearly three dozen U.S. automobile yellow nonmetallic monocoats (1974-1989), while Chrome Titanate appears to have been used in only a few yellow and orange nonmetallic monocoats. The use of the titanate pigments likely increased after this time period as they were replacements for lead chromate pigments (last used in a U.S. automobile original finish in the early 1990s), and are more amenable for use in basecoat/clearcoat finishes than in monocoats. Minor distortions of the infrared absorptions of rutile, anatase, and the titanates obtained using accessories with diamond windows were noted, and their origins are discussed."
525636,Sun et al. 2009,Modulation of histone methylation and MLH1 gene silencing by hexavalent chromium,"Hexavalent chromium [Cr(VI)] is a mutagen and carcinogen, and Occupational exposure can lead to lung cancers and other adverse health effects. Genetic changes resulting from DNA damage have been proposed as an important: mechanism that mediates chromate's carcinogenicity. Here we show that chromate exposure of human lung A549 cells increased global levels of di- and tri-methylated histone H3 lysine 9 (H3K9) and lysine 4 (H3K4) but decreased the levels Of tFi-methylated histone H3 lysine 27 (H3K27) and di-methylated histone H3 arginine 2 (H3R2). Most interestingly, H3K9 dimethylation was enriched in the human MLH1 gene promoter following chromate exposure and this was correlated with decreased MLH1 mRNA expression. Chromate exposure increased the protein as well as mRNA levels of G9a a histone methyltransferase that specifically methylates H3K9. This Cr(VI)-induced increase in G9a may account for the global elevation of H3K9 dimethylation. Furthermore, Supplementation with ascorbate, the primary reductant of Cr(VI) and also an essential cofactor for the histone demethylase activity, partially reversed the H3K9 dimethylation induced by chromate. Thus our studies Suggest that Cr(VI) may target histone methyltransferases and demethylases, which in turn affect both global and gene promoter specific histone methylation, leading to the silencing of specific tumor suppressor genes Such as MLH1. (C) 2009 Elsevier Inc. All rights reserved.","Modulation of histone methylation and MLH1 gene silencing by hexavalent chromium Abs: Hexavalent chromium [Cr(VI)] is a mutagen and carcinogen, and Occupational exposure can lead to lung cancers and other adverse health effects. Genetic changes resulting from DNA damage have been proposed as an important: mechanism that mediates chromate's carcinogenicity. Here we show that chromate exposure of human lung A549 cells increased global levels of di- and tri-methylated histone H3 lysine 9 (H3K9) and lysine 4 (H3K4) but decreased the levels Of tFi-methylated histone H3 lysine 27 (H3K27) and di-methylated histone H3 arginine 2 (H3R2). Most interestingly, H3K9 dimethylation was enriched in the human MLH1 gene promoter following chromate exposure and this was correlated with decreased MLH1 mRNA expression. Chromate exposure increased the protein as well as mRNA levels of G9a a histone methyltransferase that specifically methylates H3K9. This Cr(VI)-induced increase in G9a may account for the global elevation of H3K9 dimethylation. Furthermore, Supplementation with ascorbate, the primary reductant of Cr(VI) and also an essential cofactor for the histone demethylase activity, partially reversed the H3K9 dimethylation induced by chromate. Thus our studies Suggest that Cr(VI) may target histone methyltransferases and demethylases, which in turn affect both global and gene promoter specific histone methylation, leading to the silencing of specific tumor suppressor genes Such as MLH1. (C) 2009 Elsevier Inc. All rights reserved."
525379,Subramanian et al. 2006,Reproductive toxicity of chromium in adult bonnet monkeys (Macaca radiata Geoffrey). Reversible oxidative stress in the semen,"The present study was designed to test the hypothesis that oxidative stress mediates chromium-induced reproductive toxicity. Monthly semen samples were collected from adult monkeys (Macaca radiata), which were exposed to varying doses (50, 100, 200 and 400 ppm) of chromium (as potassium dichromate) for 6 months through drinking water. Chromium treatment decreased sperm count, sperm forward motility and the specific activities of antioxidant enzymes, superoxide dismutase and catalase, and the concentration of reduced glutathione in both seminal plasma and sperm in a dose- and duration-dependent manner. On the other hand, the quantum of hydrogen peroxide in the seminal plasma/sperm from monkeys exposed to chromium increased with increasing dose and duration of chromium exposure. All these changes were reversed after 6 months of chromium-free exposure period. Simultaneous supplementation of vitamin C (0.5 g/L; 1.0 g/L; 2.0 g/L) prevented the development of chromium-induced oxidative stress. Data support the hypothesis and show that chronic chromium exposure induces a reversible oxidative stress in the seminal plasma and sperm by creating an imbalance between reactive oxygen species and antioxidant system, leading to sperm death and reduced motility of live sperm. (c) 2006 Elsevier Inc. All rights reserved.","Reproductive toxicity of chromium in adult bonnet monkeys (Macaca radiata Geoffrey). Reversible oxidative stress in the semen Abs: The present study was designed to test the hypothesis that oxidative stress mediates chromium-induced reproductive toxicity. Monthly semen samples were collected from adult monkeys (Macaca radiata), which were exposed to varying doses (50, 100, 200 and 400 ppm) of chromium (as potassium dichromate) for 6 months through drinking water. Chromium treatment decreased sperm count, sperm forward motility and the specific activities of antioxidant enzymes, superoxide dismutase and catalase, and the concentration of reduced glutathione in both seminal plasma and sperm in a dose- and duration-dependent manner. On the other hand, the quantum of hydrogen peroxide in the seminal plasma/sperm from monkeys exposed to chromium increased with increasing dose and duration of chromium exposure. All these changes were reversed after 6 months of chromium-free exposure period. Simultaneous supplementation of vitamin C (0.5 g/L; 1.0 g/L; 2.0 g/L) prevented the development of chromium-induced oxidative stress. Data support the hypothesis and show that chronic chromium exposure induces a reversible oxidative stress in the seminal plasma and sperm by creating an imbalance between reactive oxygen species and antioxidant system, leading to sperm death and reduced motility of live sperm. (c) 2006 Elsevier Inc. All rights reserved."
524137,Stackpole et al. 2007,Homologous recombination repair protects against particulate chromate-induced chromosome instability in Chinese hamster cells,"Particulate hexavalent chromium [Cr(VI)] compounds are well-established human carcinogens. Cr(VI)-induced tumors are characterized by chromosomal instability (CIN); however, the mechanisms of this effect are unknown. We investigated the hypothesis that homologous recombination (HR) repair of DNA double-strand breaks protect cells from Cr(VI)-induced CIN by focusing on the XRCC3 and RAD51C genes, which play an important role in cellular resistance to DNA double-strand breaks. We used Chinese hamster cells defective in each HR gene (irs3 for RAD51C and irs1SF for XRCC3) and compared with their wildtype parental and cDNA-complemented controls. We found that the intracellular Cr ion levels varied among the cell lines after particulate chromate treatment. Importantly, accounting for differences in Cr ion levels, we discovered that XRCC3 and RAD51C cells treated with lead chromate had increased cytotoxicity and chromosomal aberrations, relative to wildtype and cDNA-complimented cells. We also observed the emergence of high levels of chromatid exchanges in the two mutant cell lines. For example, 1 mu g/cm(2) lead chromate induced 20 and 32 exchanges in XRCC3- and RAD51C-deficient cells, respectively, whereas no exchanges were detected in the wildtype and cDNA-complemented cells. These observations suggest that HR protects cells from Cr(VI)-induced CIN, consistent with the ability of particulate Cr(VI) to induce double-strand breaks. (c) 2007 Elsevier B.V. All rights reserved.","Homologous recombination repair protects against particulate chromate-induced chromosome instability in Chinese hamster cells Abs: Particulate hexavalent chromium [Cr(VI)] compounds are well-established human carcinogens. Cr(VI)-induced tumors are characterized by chromosomal instability (CIN); however, the mechanisms of this effect are unknown. We investigated the hypothesis that homologous recombination (HR) repair of DNA double-strand breaks protect cells from Cr(VI)-induced CIN by focusing on the XRCC3 and RAD51C genes, which play an important role in cellular resistance to DNA double-strand breaks. We used Chinese hamster cells defective in each HR gene (irs3 for RAD51C and irs1SF for XRCC3) and compared with their wildtype parental and cDNA-complemented controls. We found that the intracellular Cr ion levels varied among the cell lines after particulate chromate treatment. Importantly, accounting for differences in Cr ion levels, we discovered that XRCC3 and RAD51C cells treated with lead chromate had increased cytotoxicity and chromosomal aberrations, relative to wildtype and cDNA-complimented cells. We also observed the emergence of high levels of chromatid exchanges in the two mutant cell lines. For example, 1 mu g/cm(2) lead chromate induced 20 and 32 exchanges in XRCC3- and RAD51C-deficient cells, respectively, whereas no exchanges were detected in the wildtype and cDNA-complemented cells. These observations suggest that HR protects cells from Cr(VI)-induced CIN, consistent with the ability of particulate Cr(VI) to induce double-strand breaks. (c) 2007 Elsevier B.V. All rights reserved."
521498,Shrestha et al. 2007,Investigations on different positions of electrodes and their effects on the distribution of Cr at the water sediment interface,"In most mining areas, significant concentrations of metals such as Pb, Cu, Cr, Zn, Cd, Fe, Mn, Co, Ni, Hg, Ar, halogenated organic compounds and radionuclides are found. Of those, Cr is one of the well-known heavy metals that forms toxic species. It is necessary to study the mobilization and accumulation of Cr at the sediment water interface in an electric field at varying different positions and conditions of the electrode arrangement. The tests were carried out with a natural sediment containing heavy metals from the river Weisse Elster (Germany). The electrokinctic experiments have been performed in columns filled with sediment using electrodes made of conductive polymers (polyethylene with carbon black) at a maximum current density of 0.5 mA/cm(2). The experimental results suggest that the mobilization and accumulation of Cr highly depends on chemical factors for e.g., pH value, redox potential, respectively redox status and the content of Fe, Al and organic matter in the soil or sediment. The sorption of Cr (III, VI) is very high in the pH range > 4.5. As expected, a high mobilization of Cr (III, VI) was seen in the case of the experiments with the anode at the sediment, because the pH value was lower than mentioned above. On the opposite, the best conditions for the Cr (III, VI) immobilization is high pH values (cathode at the sediment).","Investigations on different positions of electrodes and their effects on the distribution of Cr at the water sediment interface Abs: In most mining areas, significant concentrations of metals such as Pb, Cu, Cr, Zn, Cd, Fe, Mn, Co, Ni, Hg, Ar, halogenated organic compounds and radionuclides are found. Of those, Cr is one of the well-known heavy metals that forms toxic species. It is necessary to study the mobilization and accumulation of Cr at the sediment water interface in an electric field at varying different positions and conditions of the electrode arrangement. The tests were carried out with a natural sediment containing heavy metals from the river Weisse Elster (Germany). The electrokinctic experiments have been performed in columns filled with sediment using electrodes made of conductive polymers (polyethylene with carbon black) at a maximum current density of 0.5 mA/cm(2). The experimental results suggest that the mobilization and accumulation of Cr highly depends on chemical factors for e.g., pH value, redox potential, respectively redox status and the content of Fe, Al and organic matter in the soil or sediment. The sorption of Cr (III, VI) is very high in the pH range > 4.5. As expected, a high mobilization of Cr (III, VI) was seen in the case of the experiments with the anode at the sediment, because the pH value was lower than mentioned above. On the opposite, the best conditions for the Cr (III, VI) immobilization is high pH values (cathode at the sediment)."
518327,Savery et al. 2007,Role of the Fancg gene in protecting cells from particulate chromate-induced chromosome instability,"Particulate hexavalent chromium (Cr(VI)) is a known human lung carcinogen. Cr(VI)-induced tumors exhibit chromosome instability (CIN), but the mechanisms underlying these effects are unknown. We investigated a possible role for the Fanconi anemia (FA) pathway in particulate Cr(VI)-induced chromosomal damage by focusing on the Fancg gene, which plays an important role in cellular resistance to DNA interstrand crosslinks. We used the isogenic Chinese hamster ovary (CHO) KO40fancg mutant compared with parental and gene-complemented cells. We found that fancg cells treated with lead chromate had lower intracellular Cr ion levels than control cell lines. Accounting for differences of Cr ion levels between cell lines, we discovered that fancg cells treated with lead chromate had increased cytotoxicity and chromosomal aberrations, which was not observed after restoring the Fancg gene. Chromosomal damage was manifest as increased total chromosome damage and percent metaphases with damage, specifically an increase in chromatid and isochromatid breaks. We conclude that Fancg protects cells from particulate Cr(VI)-induced cytotoxicity and chromosome damage, which is consistent with the known sensitivity of fancg cells to crosslinking damage and the ability of Cr(VI) to produce crosslinks. (c) 2006 Elsevier B.V. All rights reserved.","Role of the Fancg gene in protecting cells from particulate chromate-induced chromosome instability Abs: Particulate hexavalent chromium (Cr(VI)) is a known human lung carcinogen. Cr(VI)-induced tumors exhibit chromosome instability (CIN), but the mechanisms underlying these effects are unknown. We investigated a possible role for the Fanconi anemia (FA) pathway in particulate Cr(VI)-induced chromosomal damage by focusing on the Fancg gene, which plays an important role in cellular resistance to DNA interstrand crosslinks. We used the isogenic Chinese hamster ovary (CHO) KO40fancg mutant compared with parental and gene-complemented cells. We found that fancg cells treated with lead chromate had lower intracellular Cr ion levels than control cell lines. Accounting for differences of Cr ion levels between cell lines, we discovered that fancg cells treated with lead chromate had increased cytotoxicity and chromosomal aberrations, which was not observed after restoring the Fancg gene. Chromosomal damage was manifest as increased total chromosome damage and percent metaphases with damage, specifically an increase in chromatid and isochromatid breaks. We conclude that Fancg protects cells from particulate Cr(VI)-induced cytotoxicity and chromosome damage, which is consistent with the known sensitivity of fancg cells to crosslinking damage and the ability of Cr(VI) to produce crosslinks. (c) 2006 Elsevier B.V. All rights reserved."
515405,Rodrigues and  Formoso 2005,Exposure to selected heavy metals through water ingestion in an area under the influence of tanneries,"This study evaluated the potential toxicological risk posed to human health due to the exposure to heavy metals by water ingestion in an area affected by tanneries - the Cadeia-Feitoria hydrographic basin (Brazil). River water was collected at 10 sites, every 3 months, from July 1999 to April 2000. After acid digestion, total metal concentration was determined by inductively coupled plasma optical emission spectrometry (Cd, Cu, Cr, Ni, Zn), flame atomic absorption (Al, Fe, Pb, Mn), or cold vapor atomic absorption spectrometry (Hg). Cr(VI) was complexed with diphenyl-carbazide and detected by UV-vis spectrometry. In order to quantify the risk of exposure, the risk assessment methodology employed by the Environmental Protection Agency of the United States was applied at a screening level. The assumed scenarios included extreme exposure patterns ( ingestion of untreated water, conversion of Cr(III) to Cr(VI), temporal peaks of pollution). Fe, Al, Cd, Hg, and Pb were not included in the risk analysis, since they showed a low toxicity potential or were undetected in the samples. The selected metals presented Hazard Quotients < 1, in the following order of increasing risk: Cu < Cr( III) < Zn < Ni < Mn < Cr(VI). Hazard indexes, representing the additive effect of contaminants, were also low in the basin (< 1), but comparatively increased in the lower reach of Feitoria and Cadeia Rivers. Although noncarcinogenic risk levels did not suggest possible adverse toxicological effects to the human population, a considerable deviation from background conditions was observed downstream the area where tanneries are mainly located.","Exposure to selected heavy metals through water ingestion in an area under the influence of tanneries Abs: This study evaluated the potential toxicological risk posed to human health due to the exposure to heavy metals by water ingestion in an area affected by tanneries - the Cadeia-Feitoria hydrographic basin (Brazil). River water was collected at 10 sites, every 3 months, from July 1999 to April 2000. After acid digestion, total metal concentration was determined by inductively coupled plasma optical emission spectrometry (Cd, Cu, Cr, Ni, Zn), flame atomic absorption (Al, Fe, Pb, Mn), or cold vapor atomic absorption spectrometry (Hg). Cr(VI) was complexed with diphenyl-carbazide and detected by UV-vis spectrometry. In order to quantify the risk of exposure, the risk assessment methodology employed by the Environmental Protection Agency of the United States was applied at a screening level. The assumed scenarios included extreme exposure patterns ( ingestion of untreated water, conversion of Cr(III) to Cr(VI), temporal peaks of pollution). Fe, Al, Cd, Hg, and Pb were not included in the risk analysis, since they showed a low toxicity potential or were undetected in the samples. The selected metals presented Hazard Quotients < 1, in the following order of increasing risk: Cu < Cr( III) < Zn < Ni < Mn < Cr(VI). Hazard indexes, representing the additive effect of contaminants, were also low in the basin (< 1), but comparatively increased in the lower reach of Feitoria and Cadeia Rivers. Although noncarcinogenic risk levels did not suggest possible adverse toxicological effects to the human population, a considerable deviation from background conditions was observed downstream the area where tanneries are mainly located."
515391,Rodrigues et al. 2009,Human bronchial epithelial cells malignantly transformed by hexavalent chromium exhibit an aneuploid phenotype but no microsatellite instability,"Hexavalent chromium [Cr(VI)] is a well-recognized human lung carcinogen. In order to gain further insight into Cr(VI)-induced carcinogenesis, we have established an adequate in vitro cellular model for the study of this process. To this end, BEAS-2B cells were used. Chronic exposure of cells to 1 mu M Cr(VI) induced changes in the cells' ploicly and a decrease in cloning efficiency, although cultures continued to progress to confluence. After prolonged exposure (12 passages), the culture became heterogeneous, exhibiting areas where apparently normal epithelial cells and morphologically altered cells coexisted. Subsequent culture at a very low density strongly accentuated the Cr(Vi)-induced changes in morphology and pattern of growth. Three individual colonies were then ring-cloned and expanded into three subclonal aneuploid cell lines. These subclonal cell lines showed changes in growth pattern and morphology, as well as a karyotype drift concomitant with the overexpression of genes commonly involved in malignant transformation (c-MYC. EGFR, HIF-1 alpha and LDH-A). Moreover, when one of these cell lines (RenG2) was injected into nude mice, it showed the ability to induce tumors. This cell line revealed no microsatellite instability (MSI), which points to the expression of a functional MLH1 protein and an active mismatch repair (MMR) system. Therefore, the progression to malignancy of the BEAS-2B cells involved Cr(Vi)-induced transformants that retained the ability to repair DNA damage, suggesting that genotoxicity underlies the ongoing carcinogenic process. (C) 2009 Elsevier B.V. All rights reserved.","Human bronchial epithelial cells malignantly transformed by hexavalent chromium exhibit an aneuploid phenotype but no microsatellite instability Abs: Hexavalent chromium [Cr(VI)] is a well-recognized human lung carcinogen. In order to gain further insight into Cr(VI)-induced carcinogenesis, we have established an adequate in vitro cellular model for the study of this process. To this end, BEAS-2B cells were used. Chronic exposure of cells to 1 mu M Cr(VI) induced changes in the cells' ploicly and a decrease in cloning efficiency, although cultures continued to progress to confluence. After prolonged exposure (12 passages), the culture became heterogeneous, exhibiting areas where apparently normal epithelial cells and morphologically altered cells coexisted. Subsequent culture at a very low density strongly accentuated the Cr(Vi)-induced changes in morphology and pattern of growth. Three individual colonies were then ring-cloned and expanded into three subclonal aneuploid cell lines. These subclonal cell lines showed changes in growth pattern and morphology, as well as a karyotype drift concomitant with the overexpression of genes commonly involved in malignant transformation (c-MYC. EGFR, HIF-1 alpha and LDH-A). Moreover, when one of these cell lines (RenG2) was injected into nude mice, it showed the ability to induce tumors. This cell line revealed no microsatellite instability (MSI), which points to the expression of a functional MLH1 protein and an active mismatch repair (MMR) system. Therefore, the progression to malignancy of the BEAS-2B cells involved Cr(Vi)-induced transformants that retained the ability to repair DNA damage, suggesting that genotoxicity underlies the ongoing carcinogenic process. (C) 2009 Elsevier B.V. All rights reserved."
513345,Rana 2008,Metals and apoptosis: Recent developments,"Apoptosis, also known as programmed cell death is a highly regulated and crucial process found in all multicellular organisms. It is not only implicated in regulatory mechanisms of cells, but has been attributed to a number of diseases, i.e. inflammation, malignancy, autoimmunity and neurodegeneration. A variety of toxins can induce apoptosis. Carcinogenic transition metals, viz. cadmium, chromium and nickel promote apoptosis along with DNA base modifications, strand breaks and rearrangements. Generation of reactive oxygen species, accumulation of Ca2+ upregulation of caspase-3, down regulation of bcl-2, and deficiency of p-53 lead to arsenic-induced apoptosis. In the case of cadmium, metallothionein expression determines the choice between apoptosis and necrosis. Reactive oxygen species (ROS) and p53 contribute in apoptosis caused by chromium. Immuno suppressive mechanism contribute in lead-induced apoptosis whereas in the case of mercury, p38 mediated caspase activation regulate apoptosis. Nickel kills the cells by apoptotic pathways. Copper induces apoptosis by p53 dependent and independent pathways. Beryllium stimulates the formation of ROS that play a role in Be-induced macrophage apoptosis. Selenium induces apoptosis by producing superoxide that activates p53. Thus. disorders of apoptosis may play a critical role in some of the most debilitating metal-induced afflictions including hepatotoxicity, renal toxicity, neurotoxicity, autoimmunity and carcinogenesis. An understanding of metal-induced apoptosis will be helpful in the development of preventive molecular strategies. (C) 2008 Elsevier GmbH. All rights reserved.","Metals and apoptosis: Recent developments Abs: Apoptosis, also known as programmed cell death is a highly regulated and crucial process found in all multicellular organisms. It is not only implicated in regulatory mechanisms of cells, but has been attributed to a number of diseases, i.e. inflammation, malignancy, autoimmunity and neurodegeneration. A variety of toxins can induce apoptosis. Carcinogenic transition metals, viz. cadmium, chromium and nickel promote apoptosis along with DNA base modifications, strand breaks and rearrangements. Generation of reactive oxygen species, accumulation of Ca2+ upregulation of caspase-3, down regulation of bcl-2, and deficiency of p-53 lead to arsenic-induced apoptosis. In the case of cadmium, metallothionein expression determines the choice between apoptosis and necrosis. Reactive oxygen species (ROS) and p53 contribute in apoptosis caused by chromium. Immuno suppressive mechanism contribute in lead-induced apoptosis whereas in the case of mercury, p38 mediated caspase activation regulate apoptosis. Nickel kills the cells by apoptotic pathways. Copper induces apoptosis by p53 dependent and independent pathways. Beryllium stimulates the formation of ROS that play a role in Be-induced macrophage apoptosis. Selenium induces apoptosis by producing superoxide that activates p53. Thus. disorders of apoptosis may play a critical role in some of the most debilitating metal-induced afflictions including hepatotoxicity, renal toxicity, neurotoxicity, autoimmunity and carcinogenesis. An understanding of metal-induced apoptosis will be helpful in the development of preventive molecular strategies. (C) 2008 Elsevier GmbH. All rights reserved."
512954,Raghunathan et al. 2009,Response to chronic exposure to hexavalent chromium in human monocytes,"Elevated circulating levels of metal ions, particularly chromium, have been measured in the blood of patients with metal hip implants, and this has lead to concerns about the long term safety of the prostheses. For example, depletion of lymphocytes has been reported in vivo in patients with metallic prostheses, and correlated with elevated chromium and cobalt concentrations in blood. However, the implications for immune function are unclear. We have assessed the in vitro responses of U937 human monocytes to chronic exposure (4 weeks) to Cr (VI) ions at concentrations which have been measured in patients with metal artificial hip implants (0.05-0.5 mu M). Chronic exposure to these low clinically relevant concentrations of Cr (VI) induced a potent adaptive response with elevated glutathione-S-transferase (pi) expression and increased activities and expression of reactive oxygen scavengers, superoxide dismutases, catalase and glutathione peroxidase. Such direct toxicity of Cr ions may contribute to the effects of metal implants on lymphocyte populations in vivo. (C) 2009 Elsevier Ltd. All rights reserved.","Response to chronic exposure to hexavalent chromium in human monocytes Abs: Elevated circulating levels of metal ions, particularly chromium, have been measured in the blood of patients with metal hip implants, and this has lead to concerns about the long term safety of the prostheses. For example, depletion of lymphocytes has been reported in vivo in patients with metallic prostheses, and correlated with elevated chromium and cobalt concentrations in blood. However, the implications for immune function are unclear. We have assessed the in vitro responses of U937 human monocytes to chronic exposure (4 weeks) to Cr (VI) ions at concentrations which have been measured in patients with metal artificial hip implants (0.05-0.5 mu M). Chronic exposure to these low clinically relevant concentrations of Cr (VI) induced a potent adaptive response with elevated glutathione-S-transferase (pi) expression and increased activities and expression of reactive oxygen scavengers, superoxide dismutases, catalase and glutathione peroxidase. Such direct toxicity of Cr ions may contribute to the effects of metal implants on lymphocyte populations in vivo. (C) 2009 Elsevier Ltd. All rights reserved."
512142,Pritchard et al. 2005,"Resistance to apoptosis, increased growth potential, and altered gene expression in cells that survived genotoxic hexavalent chromium Cr(VI) exposure","Certain hexavalent chromium [Cr(VI)] compounds are known genotoxic respiratory carcinogens, which induce apoptosis as a predominant mode of cell death. Selection of cells that are resistant to apoptosis may be a factor in tumour progression. We developed sub-populations of telomerase-transfected human fibroblasts (BJ-hTERT) that survived a 99% clonogenically lethal exposure to Cr(VI) (B-5Cr). B-5Cr cells were markedly resistant to apoptosis induced by several agents and exhibited increased clonogenic survival, especially at apoptogenic doses. B-5Cr cells did not exhibit altered cellular uptake of Cr(VI) and retained a normal p53 response to Cr(VI) exposure. We conducted large-scale gene expression analysis at different time-points after a secondary genotoxic Cr(VI) insult in B-5Cr and BJ-hTERT cells using Affymetrix Genechip(R) human genome arrays. Cr(VI) exposure led to differential regulation of many genes, which affect a diverse set of cellular activities such as transcription, signal transduction, stress response, cell adhesion, DNA repair, apoptosis and cell cycle modulation. We compared Cr(VI)-induced altered gene expression in the B-5Cr cells to that in the parental cells and identified 223, 147 and 204 genes with at least a two-fold difference in expression at 4, 8 and 18 h after exposure, respectively. Cluster analysis by gene function revealed altered expression of genes involved in apoptosis, cell cycle regulation and DNA repair. Our data suggest an alteration in gene expression that may favor cell survival and/or incomplete DNA repair after genotoxic exposure. Selection of cells with altered expression of these genes may constitute the early stages of tumour progression.","Resistance to apoptosis, increased growth potential, and altered gene expression in cells that survived genotoxic hexavalent chromium Cr(VI) exposure Abs: Certain hexavalent chromium [Cr(VI)] compounds are known genotoxic respiratory carcinogens, which induce apoptosis as a predominant mode of cell death. Selection of cells that are resistant to apoptosis may be a factor in tumour progression. We developed sub-populations of telomerase-transfected human fibroblasts (BJ-hTERT) that survived a 99% clonogenically lethal exposure to Cr(VI) (B-5Cr). B-5Cr cells were markedly resistant to apoptosis induced by several agents and exhibited increased clonogenic survival, especially at apoptogenic doses. B-5Cr cells did not exhibit altered cellular uptake of Cr(VI) and retained a normal p53 response to Cr(VI) exposure. We conducted large-scale gene expression analysis at different time-points after a secondary genotoxic Cr(VI) insult in B-5Cr and BJ-hTERT cells using Affymetrix Genechip(R) human genome arrays. Cr(VI) exposure led to differential regulation of many genes, which affect a diverse set of cellular activities such as transcription, signal transduction, stress response, cell adhesion, DNA repair, apoptosis and cell cycle modulation. We compared Cr(VI)-induced altered gene expression in the B-5Cr cells to that in the parental cells and identified 223, 147 and 204 genes with at least a two-fold difference in expression at 4, 8 and 18 h after exposure, respectively. Cluster analysis by gene function revealed altered expression of genes involved in apoptosis, cell cycle regulation and DNA repair. Our data suggest an alteration in gene expression that may favor cell survival and/or incomplete DNA repair after genotoxic exposure. Selection of cells with altered expression of these genes may constitute the early stages of tumour progression."
508485,Pandey et al. 2007,"Studies on Cr(VI), Pb(II) and Cu(II) adsorption-desorption using calcium alginate as biopolymer","The aim of this study was to investigate the Cr(VI), Pb(II) and Cu(II) biosorption potential of calcium alginate from aqueous solution and to screen a variety of desorbing agents, in order to access the efficiency of desorption and regeneration of the biosorbent in multiple sorption-desorption cycles. Calcium alginate beads was found to remove heavy metal ions efficiently from aqueous solution with selectivity in the order of Cr(VI)> Cu(II)> Pb(II).The biosorption of metal ions by calcium alginate beads decreased as the initial concentration of metal ions increased in the medium. The maximum heavy metal ions adsorbed was found to be 238,154,120 mg/g calcium alginate beads for Cr(VI), Cu(II) and Pb(II) respectively. The maximum uptake of metal ions was obtained at pH 2.0. Above pH 2.0, biosorption of metal ions by calcium alginate beads was found to be relatively constant for Pb(II) and Cu(II) ions, biosorption of Cr(VI) still increased upto pH 3.0 having 86% removal efficiency. At temperature 35 degrees C, the biosorption of metal ions was found to be highest, with increase or decrease in temperature resulted in a decrease in the metal ions uptake capacity. The sorption data of all three metal ions conformed well the Langmuir isotherm. The bound metal ions could be eluted successfully using 0.1 M EDTA. The successive sorption-desorption studies employing calcium alginate beads indicated that the beads could be regenerated without showing the significant loss in adsorption capacity even after second cycle of adsorption-desorption. The results suggest that calcium alginate beads can be used as a biosorbent for an efficient removal of heavy metal ions from aqueous solution.","Studies on Cr(VI), Pb(II) and Cu(II) adsorption-desorption using calcium alginate as biopolymer Abs: The aim of this study was to investigate the Cr(VI), Pb(II) and Cu(II) biosorption potential of calcium alginate from aqueous solution and to screen a variety of desorbing agents, in order to access the efficiency of desorption and regeneration of the biosorbent in multiple sorption-desorption cycles. Calcium alginate beads was found to remove heavy metal ions efficiently from aqueous solution with selectivity in the order of Cr(VI)> Cu(II)> Pb(II).The biosorption of metal ions by calcium alginate beads decreased as the initial concentration of metal ions increased in the medium. The maximum heavy metal ions adsorbed was found to be 238,154,120 mg/g calcium alginate beads for Cr(VI), Cu(II) and Pb(II) respectively. The maximum uptake of metal ions was obtained at pH 2.0. Above pH 2.0, biosorption of metal ions by calcium alginate beads was found to be relatively constant for Pb(II) and Cu(II) ions, biosorption of Cr(VI) still increased upto pH 3.0 having 86% removal efficiency. At temperature 35 degrees C, the biosorption of metal ions was found to be highest, with increase or decrease in temperature resulted in a decrease in the metal ions uptake capacity. The sorption data of all three metal ions conformed well the Langmuir isotherm. The bound metal ions could be eluted successfully using 0.1 M EDTA. The successive sorption-desorption studies employing calcium alginate beads indicated that the beads could be regenerated without showing the significant loss in adsorption capacity even after second cycle of adsorption-desorption. The results suggest that calcium alginate beads can be used as a biosorbent for an efficient removal of heavy metal ions from aqueous solution."
507532,Ortega et al. 2005,Chromium oxidation state imaging in mammalian cells exposed in vitro to soluble or particulate chromate compounds,"Hexavalent chromium compounds are known carcinogens for the respiratory tract in humans. The mechanism of cell transformation by hexavalent chromium compounds is not fully understood although a role for intracellular reduction is sought. The aim of this study was to determine the distribution of Cr valence states in human cells after in vitro exposure to soluble or particulate chromium compounds. A synchrotron X-ray-based microprobe was used to investigate the cellular reduction of Cr(VI) and to image chromium oxidation states in cells. It was shown that soluble Cr(VI) compounds are fully reduced to Cr(III) in cells. Cr(III) is homogeneously distributed within the cell volume and therefore present within the nucleus. In the case of low solubility particulate chromate compounds, Cr(VI) can coexist in the cell environment, as particles in the perinuclear region, together with intracellular and intranuclear Cr(III). Chemical distribution maps also suggest that intracellular Cr(III) originates from extracellular dissolution and reduction of lead chromate rather than from intracellular engulfed particles. The possible stronger carcinogenicity of low solubility chromate vs soluble chromate compounds may derive from the combinative genotoxic effects of intranuclear Cr(III) and the persistent exposure to a strong oxidant, Cr(VI).","Chromium oxidation state imaging in mammalian cells exposed in vitro to soluble or particulate chromate compounds Abs: Hexavalent chromium compounds are known carcinogens for the respiratory tract in humans. The mechanism of cell transformation by hexavalent chromium compounds is not fully understood although a role for intracellular reduction is sought. The aim of this study was to determine the distribution of Cr valence states in human cells after in vitro exposure to soluble or particulate chromium compounds. A synchrotron X-ray-based microprobe was used to investigate the cellular reduction of Cr(VI) and to image chromium oxidation states in cells. It was shown that soluble Cr(VI) compounds are fully reduced to Cr(III) in cells. Cr(III) is homogeneously distributed within the cell volume and therefore present within the nucleus. In the case of low solubility particulate chromate compounds, Cr(VI) can coexist in the cell environment, as particles in the perinuclear region, together with intracellular and intranuclear Cr(III). Chemical distribution maps also suggest that intracellular Cr(III) originates from extracellular dissolution and reduction of lead chromate rather than from intracellular engulfed particles. The possible stronger carcinogenicity of low solubility chromate vs soluble chromate compounds may derive from the combinative genotoxic effects of intranuclear Cr(III) and the persistent exposure to a strong oxidant, Cr(VI)."
505122,Nestmann and  Zhang 2007,Chromosome aberration test of Pigment Yellow 34 (lead chromate) in Chinese hamster ovary cells,"Lead chromate pigment in the form of the commercial pigment, Pigment Yellow 34, CAS No. 1344-37-2, used in the plastics and coatings industries, did not induce chromosome aberrations in Chinese hamster ovary (CHO) cell line WB(L). Lead chromate pigment is essentially insoluble in water, and in an effort to test the material under realistic conditions, no attempt to solubilize the pigment was made. These results are significant because others have reported lead chromate to cause genotoxicity in various assays, but only under conditions in which its aqueous solubility was artificially enhanced. (c) 2007 Elsevier B.V. All rights reserved.","Chromosome aberration test of Pigment Yellow 34 (lead chromate) in Chinese hamster ovary cells Abs: Lead chromate pigment in the form of the commercial pigment, Pigment Yellow 34, CAS No. 1344-37-2, used in the plastics and coatings industries, did not induce chromosome aberrations in Chinese hamster ovary (CHO) cell line WB(L). Lead chromate pigment is essentially insoluble in water, and in an effort to test the material under realistic conditions, no attempt to solubilize the pigment was made. These results are significant because others have reported lead chromate to cause genotoxicity in various assays, but only under conditions in which its aqueous solubility was artificially enhanced. (c) 2007 Elsevier B.V. All rights reserved."
504935,Nedelkova et al. 2007,Microbacterium isolates from the vicinity of a radioactive waste depository and their interactions with uranium,"Three oligotrophic bacterial strains were cultured from the ground water of the deep-well monitoring site S15 of the Siberian radioactive waste depository Tomsk-7, Russia. They were affiliated with Actinobacteria from the genus Microbacterium. The almost fully sequenced 16S rRNA genes of two of the isolates, S15-M2 and S15-M5, were identical to those of cultured representatives of the species Microbacterium oxydans. The third isolate, S15-M4, shared 99.8% of 16S rRNA gene identity with them. The latter isolate possessed a distinct cell morphology as well as carbon source utilization pattern from the M. oxydans strains S15-M2 and S15-M5. The three isolates tolerated equal amounts of uranium, lead, copper, silver and chromium but they differed in their tolerance of cadmium and nickel. The cells of all three strains accumulated high amounts of uranium, i.e. up to 240 mg U (g dry biomass)(-1) in the case of M. oxydans S15-M2. X-ray absorption spectroscopy (XAS) analysis showed that this strain precipitated U(VI) at pH 4.5 as a meta-autunite-like phase. At pH 2, the uranium formed complexes with organically bound phosphate groups on the cell surface. The results of the XAS studies were consistent with those obtained by transmission electron microscopy (TEM) and energy dispersive X-ray analysis (EDX).","Microbacterium isolates from the vicinity of a radioactive waste depository and their interactions with uranium Abs: Three oligotrophic bacterial strains were cultured from the ground water of the deep-well monitoring site S15 of the Siberian radioactive waste depository Tomsk-7, Russia. They were affiliated with Actinobacteria from the genus Microbacterium. The almost fully sequenced 16S rRNA genes of two of the isolates, S15-M2 and S15-M5, were identical to those of cultured representatives of the species Microbacterium oxydans. The third isolate, S15-M4, shared 99.8% of 16S rRNA gene identity with them. The latter isolate possessed a distinct cell morphology as well as carbon source utilization pattern from the M. oxydans strains S15-M2 and S15-M5. The three isolates tolerated equal amounts of uranium, lead, copper, silver and chromium but they differed in their tolerance of cadmium and nickel. The cells of all three strains accumulated high amounts of uranium, i.e. up to 240 mg U (g dry biomass)(-1) in the case of M. oxydans S15-M2. X-ray absorption spectroscopy (XAS) analysis showed that this strain precipitated U(VI) at pH 4.5 as a meta-autunite-like phase. At pH 2, the uranium formed complexes with organically bound phosphate groups on the cell surface. The results of the XAS studies were consistent with those obtained by transmission electron microscopy (TEM) and energy dispersive X-ray analysis (EDX)."
504467,Nakatsu et al. 2005,Soil microbial community responses to additions of organic carbon substrates and heavy metals (Pb and Cr),"Microcosm experiments were conducted with soils contaminated with heavy metals (Pb and Cr) and aromatic hydrocarbons to determine the effects of each upon microbial community structure and function. Organic substrates were added as a driving force for change in the microbial community. Glucose represented an energy source used by a broad variety of bacteria, whereas fewer soil species were expected to use xylene. The metal amendments were chosen to inhibit the acute rate of organic mineralization by either 50% or 90%, and lower mineralization rates persisted over the entire 31-day incubation period. Significant biomass increases were abolished when metals were added in addition to organic carbon. The addition of organic carbon alone had the most significant impact on community composition and led to the proliferation of a few dominant phylotypes, as detected by PCR-denaturing gradient gel electrophoresis of bacterial 16S rRNA genes. However, the community-wide effects of heavy metal addition differed between the two carbon sources. For glucose, either Pb or Cr produced large changes and replacement with new phylotypes. In contrast, many phylotypes selected by xylene treatment were retained when either metal was added. Members of the Actinomycetales were very prevalent in microcosms with xylene and Cr(VI); gene copy numbers of biphenyl dioxygenase and phenol hydroxylase (but not other oxygenases) were elevated in these microcosms, as determined by real-time PCR. Much lower metal concentrations were needed to inhibit the catabolism of xylene than of glucose. Cr(VI) appeared to be reduced during the 31-day incubations, but in the case of glucose there was substantial microbial activity when much of the Cr(VI) remained. In the case of xylene, this was less clear.","Soil microbial community responses to additions of organic carbon substrates and heavy metals (Pb and Cr) Abs: Microcosm experiments were conducted with soils contaminated with heavy metals (Pb and Cr) and aromatic hydrocarbons to determine the effects of each upon microbial community structure and function. Organic substrates were added as a driving force for change in the microbial community. Glucose represented an energy source used by a broad variety of bacteria, whereas fewer soil species were expected to use xylene. The metal amendments were chosen to inhibit the acute rate of organic mineralization by either 50% or 90%, and lower mineralization rates persisted over the entire 31-day incubation period. Significant biomass increases were abolished when metals were added in addition to organic carbon. The addition of organic carbon alone had the most significant impact on community composition and led to the proliferation of a few dominant phylotypes, as detected by PCR-denaturing gradient gel electrophoresis of bacterial 16S rRNA genes. However, the community-wide effects of heavy metal addition differed between the two carbon sources. For glucose, either Pb or Cr produced large changes and replacement with new phylotypes. In contrast, many phylotypes selected by xylene treatment were retained when either metal was added. Members of the Actinomycetales were very prevalent in microcosms with xylene and Cr(VI); gene copy numbers of biphenyl dioxygenase and phenol hydroxylase (but not other oxygenases) were elevated in these microcosms, as determined by real-time PCR. Much lower metal concentrations were needed to inhibit the catabolism of xylene than of glucose. Cr(VI) appeared to be reduced during the 31-day incubations, but in the case of glucose there was substantial microbial activity when much of the Cr(VI) remained. In the case of xylene, this was less clear."
503135,Mortuza et al. 2005,"Toxicity and bioaccumulation of hexavalent chromium in green paramecium, Paramecium bursaria","The effects of hexavalent chromium on the cell growth of green paramecium, Paramecium bursaria (P. bursaria),were investigated in this study. Two strains (MB-1 and F, generation) of P. bursaria were incubated in lettuce media supplemented with different concentrations of potassium dichromate under light (L) L (24 hr light), L dark (LD) (12 hr light: 12 hr dark) and DD (24 hr dark) conditions, and the lC(50) values were obtained. The IC50 7-day value showed that the toxicity of potassium dichromate was light-sensitive in both strains of P. bursaria. The results of the toxic effect of chromium on the cell shape of P. bursaria (BWK-4) showed that the body ratio of P. bursaria increased, even if the cells were incubated for 24 hr with 0.5 mu M potassium dichromate solution, indicating that the cell shape of P. bursaria is very sensitive to potassium dichromate. The average amount of chromium accumulated in green paramecium ranged from 1.72 to 15.5 pg Cr/cell in a time- and concentration-dependent manner. This finding indicates the possibility of the use of P bursaria as a biomonitor and bioaccumulator for chromium contaminants in aquatic environments. The experiment with electrical stimuli into the culture of P bursaria indicated that cells accumulated at the negative electrode, suggesting that P. bursaria carried a positive charge. Thus, because the positive charge does not cause any significant absorption of chromium into the cells, P bursaria may develop a variety of mechanisms for chromium accumulation in the cell. Further research studies are required to elucidate the mechanism of chromium uptake in P. bursaria.","Toxicity and bioaccumulation of hexavalent chromium in green paramecium, Paramecium bursaria Abs: The effects of hexavalent chromium on the cell growth of green paramecium, Paramecium bursaria (P. bursaria),were investigated in this study. Two strains (MB-1 and F, generation) of P. bursaria were incubated in lettuce media supplemented with different concentrations of potassium dichromate under light (L) L (24 hr light), L dark (LD) (12 hr light: 12 hr dark) and DD (24 hr dark) conditions, and the lC(50) values were obtained. The IC50 7-day value showed that the toxicity of potassium dichromate was light-sensitive in both strains of P. bursaria. The results of the toxic effect of chromium on the cell shape of P. bursaria (BWK-4) showed that the body ratio of P. bursaria increased, even if the cells were incubated for 24 hr with 0.5 mu M potassium dichromate solution, indicating that the cell shape of P. bursaria is very sensitive to potassium dichromate. The average amount of chromium accumulated in green paramecium ranged from 1.72 to 15.5 pg Cr/cell in a time- and concentration-dependent manner. This finding indicates the possibility of the use of P bursaria as a biomonitor and bioaccumulator for chromium contaminants in aquatic environments. The experiment with electrical stimuli into the culture of P bursaria indicated that cells accumulated at the negative electrode, suggesting that P. bursaria carried a positive charge. Thus, because the positive charge does not cause any significant absorption of chromium into the cells, P bursaria may develop a variety of mechanisms for chromium accumulation in the cell. Further research studies are required to elucidate the mechanism of chromium uptake in P. bursaria."
501710,Mirabelli and  Kauppinen 2005,Occupational exposures to carcinogens in Italy: An update of CAREX database,"To update estimates of the prevalence of occupational exposures to carcinogens in Italy, the 85 CAREX agents were re-assessed. The original exposure estimates in the CAREX database were updated, taking into account changes in exposure patterns and in numbers of employsees by industrial class. The 21.8 million employees in Italy, 19.4 in industry and services, 2.4 in agriculture, had 4.2 million exposures. Prevalences of exposures were highest for environmental (passive) tobacco smoke (800,000 exposures), solar radiation (700,000), diesel engine exhaust (500,000), wood dust (280,000), silica (250,000), lead and inorganic lead compounds (230,000), benzene (180 000), hexavalent chromium compounds (160,000), glass wool (140,000), and PAHs (120,000). Exposures to carcinogens at work are still an issue in Italy and do not appear to be controlled as strictly as they should be.","Occupational exposures to carcinogens in Italy: An update of CAREX database Abs: To update estimates of the prevalence of occupational exposures to carcinogens in Italy, the 85 CAREX agents were re-assessed. The original exposure estimates in the CAREX database were updated, taking into account changes in exposure patterns and in numbers of employsees by industrial class. The 21.8 million employees in Italy, 19.4 in industry and services, 2.4 in agriculture, had 4.2 million exposures. Prevalences of exposures were highest for environmental (passive) tobacco smoke (800,000 exposures), solar radiation (700,000), diesel engine exhaust (500,000), wood dust (280,000), silica (250,000), lead and inorganic lead compounds (230,000), benzene (180 000), hexavalent chromium compounds (160,000), glass wool (140,000), and PAHs (120,000). Exposures to carcinogens at work are still an issue in Italy and do not appear to be controlled as strictly as they should be."
500514,Melucci et al. 2007,Analytical procedure for the simultaneous voltammetric determination of trace metals in food and environmental matrices. Critical comparison with atomic absorption spectroscopic measurements,"An analytical procedure fit for the simultaneous determination of copper (11), chromium(VI), thallium(I), lead(II), tin(II), antimony(III), and zinc(II) by square wave anodic stripping voltammetry (SWASV) in three interdependent environmental matrices involved in foods and food chain as meals, cereal plants and soils is described. The digestion of each matrix was carried out using a concentrated HCl-HNO3-H2SO4 (meals and cereal plants) and HCl-HNO3 (soils) acidic attack mixtures. 0.1 mol/L dibasic ammonium citrate pH 8.5 was employed as the supporting electrolyte. The voltammetric measurements were carried out using, as working electrode, a stationary hanging mercury drop electrode (HMDE) and a platinum electrode and an Ag vertical bar AgCl vertical bar KClsat electrode as auxiliary and reference electrodes, respectively. The analytical procedure was verified by the analyses of the standard reference materials: Wholemeal BCR-CRM 189, Tomato Leaves NIST-SRM 1573a and Montana Soil Moderately Elevated Traces NIST-SRM 2711. For all the elements in the certified matrix, the precision as repeatability, expressed as relative standard deviation (Sr %) was lower than 5 %. The accuracy, expressed as percentage relative error (e %) was of the order of 3-7 %, while the detection limits were in the range 0.015-0.103 mu g/g. Once set up on the standard reference materials, the analytical procedure was transferred and applied to commercial meal samples, cereal plants and soils samples drawn in sites devoted to agricultural practice. A critical comparison with spectroscopic measurements is also discussed.","Analytical procedure for the simultaneous voltammetric determination of trace metals in food and environmental matrices. Critical comparison with atomic absorption spectroscopic measurements Abs: An analytical procedure fit for the simultaneous determination of copper (11), chromium(VI), thallium(I), lead(II), tin(II), antimony(III), and zinc(II) by square wave anodic stripping voltammetry (SWASV) in three interdependent environmental matrices involved in foods and food chain as meals, cereal plants and soils is described. The digestion of each matrix was carried out using a concentrated HCl-HNO3-H2SO4 (meals and cereal plants) and HCl-HNO3 (soils) acidic attack mixtures. 0.1 mol/L dibasic ammonium citrate pH 8.5 was employed as the supporting electrolyte. The voltammetric measurements were carried out using, as working electrode, a stationary hanging mercury drop electrode (HMDE) and a platinum electrode and an Ag vertical bar AgCl vertical bar KClsat electrode as auxiliary and reference electrodes, respectively. The analytical procedure was verified by the analyses of the standard reference materials: Wholemeal BCR-CRM 189, Tomato Leaves NIST-SRM 1573a and Montana Soil Moderately Elevated Traces NIST-SRM 2711. For all the elements in the certified matrix, the precision as repeatability, expressed as relative standard deviation (Sr %) was lower than 5 %. The accuracy, expressed as percentage relative error (e %) was of the order of 3-7 %, while the detection limits were in the range 0.015-0.103 mu g/g. Once set up on the standard reference materials, the analytical procedure was transferred and applied to commercial meal samples, cereal plants and soils samples drawn in sites devoted to agricultural practice. A critical comparison with spectroscopic measurements is also discussed."
495693,Lohani et al. 2008,Seasonal variations of heavy metal contamination in river Gomti of Lucknow city region,"The present study deals with the seasonal variations in the concentrations of heavy metals namely chromium, lead and mercury by using spectrophotometric methods. The water samples were collected at regular intervals from five selected sites of river Gomti in the pre-monsoon period (months of February-May) and the post monsoon period (months of October-January). The concentrations of chromium (VI) and mercury (II) were determined by using Genesys-10 UV-VIS Spectrophotometer while lead (II) concentrations were determined using Atomic Absorption Spectrophotometer, Perkin-Elmer 5000 model. The concentrations of all the three metals were found to be higher in the pre-monsoon period than in the post-monsoon period. The statistical analysis of the data was discussed in both the seasons in terms of mean, standard deviation and coefficient of variation.","Seasonal variations of heavy metal contamination in river Gomti of Lucknow city region Abs: The present study deals with the seasonal variations in the concentrations of heavy metals namely chromium, lead and mercury by using spectrophotometric methods. The water samples were collected at regular intervals from five selected sites of river Gomti in the pre-monsoon period (months of February-May) and the post monsoon period (months of October-January). The concentrations of chromium (VI) and mercury (II) were determined by using Genesys-10 UV-VIS Spectrophotometer while lead (II) concentrations were determined using Atomic Absorption Spectrophotometer, Perkin-Elmer 5000 model. The concentrations of all the three metals were found to be higher in the pre-monsoon period than in the post-monsoon period. The statistical analysis of the data was discussed in both the seasons in terms of mean, standard deviation and coefficient of variation."
493432,Levina and  Lay 2008,Chemical properties and toxicity of chromium(III) nutritional supplements,"The status of Cr(III) as an essential micronutrient for humans is currently under question. No functional Cr(III)-containing biomolecules have been definitively described as yet, and accumulated experience in the use of Cr(III) nutritional supplements (such as [Cr(pic) 3], where pic = 2-pyridinecarboxylato) has shown no measurable benefits for nondiabetic people. Although the use of large doses of Cr(III) supplements may lead to improvements in glucose metabolism for type 2 diabetics, there is a growing concern over the possible genotoxicity of these compounds, particularly of [Cr(pic) 3]. The current perspective discusses chemical transformations of Cr(III) nutritional supplements in biological media, with implications for both beneficial and toxic actions of Cr(III) complexes, which are likely to arise from the same biochemical mechanisms, dependent on concentrations of the reactive species. These species include: (i) partial hydrolysis products of Cr(III) nutritional supplements, which are capable of binding to biological macromolecules and altering their functions; and (ii) highly reactive Cr(VI/V/IV) species and organic radicals, formed in reactions of Cr(III) with biological oxidants. Low concentrations of these species are likely to cause alterations in cell signaling (including enhancement of insulin signaling) through interactions with the active centers of regulatory enzymes in the cell membrane or in the cytoplasm, while higher concentrations are likely to produce genotoxic DNA lesions in the cell nucleus. These data suggest that the potential for genotoxic side-effects of Cr(III) complexes may outweigh their possible benefits as insulin enhancers, and that recommendations for their use as either nutritional supplements or antidiabetic drugs need to be reconsidered in light of these recent findings.","Chemical properties and toxicity of chromium(III) nutritional supplements Abs: The status of Cr(III) as an essential micronutrient for humans is currently under question. No functional Cr(III)-containing biomolecules have been definitively described as yet, and accumulated experience in the use of Cr(III) nutritional supplements (such as [Cr(pic) 3], where pic = 2-pyridinecarboxylato) has shown no measurable benefits for nondiabetic people. Although the use of large doses of Cr(III) supplements may lead to improvements in glucose metabolism for type 2 diabetics, there is a growing concern over the possible genotoxicity of these compounds, particularly of [Cr(pic) 3]. The current perspective discusses chemical transformations of Cr(III) nutritional supplements in biological media, with implications for both beneficial and toxic actions of Cr(III) complexes, which are likely to arise from the same biochemical mechanisms, dependent on concentrations of the reactive species. These species include: (i) partial hydrolysis products of Cr(III) nutritional supplements, which are capable of binding to biological macromolecules and altering their functions; and (ii) highly reactive Cr(VI/V/IV) species and organic radicals, formed in reactions of Cr(III) with biological oxidants. Low concentrations of these species are likely to cause alterations in cell signaling (including enhancement of insulin signaling) through interactions with the active centers of regulatory enzymes in the cell membrane or in the cytoplasm, while higher concentrations are likely to produce genotoxic DNA lesions in the cell nucleus. These data suggest that the potential for genotoxic side-effects of Cr(III) complexes may outweigh their possible benefits as insulin enhancers, and that recommendations for their use as either nutritional supplements or antidiabetic drugs need to be reconsidered in light of these recent findings."
492760,Lee et al. 2006,"Expression of heat shock protein and hemoglobin genes in Chironomus tentans (Diptera, chironomidae) larvae exposed to various environmental pollutants: A potential biomarker of freshwater monitoring","To identify a sensitive biomarker of freshwater monitoring, we evaluated pollutant-induced expression of heat shock proteins (HSPs) and hemoglobins (Hbs) genes in the larvae of the aquatic midge Chironomus tentans (Diptera, Chironomidae). As pollutants, we examined nonylphenol, bisphenol-A, 17 alpha-ethynyl estradiol, bis(2-ethylhexyl) phthalate, endosulfan, paraquat dichloride, chloropyriphos, fenitrothion, cadmium chloride, lead nitrate, potassium dichromate, benzo[a]pyrene and carbon tetrachloride. We also investigated larval growth as a physiological descriptor by measuring changes in the body fresh weight and dry weight after chemical exposure. The response of the HSPs gene expression by chemical exposure was rapid and sensitive to low chemical concentrations but it was not stressor specific. Interestingly, an increase in the expression of HSPs genes was observed not only in a stress inducible form (HSP70), but also in a constitutively (HSC70) expressed form. The expression of Hb genes showed chemical-specific responses: that is, alkyl phenolic compounds increased the expression of hemoglobin genes, whereas pesticides decreased the expression. As expected, molecular-level markers were more sensitive than physiological endpoints, suggesting that gene expression could be developed as an early warning biomarker in this animal. The overall results suggest that the expression of HSP and Hb genes in Chironomus could give useful information for diagnosing general health conditions in fresh water ecosystem. The expression of Hb genes, in particular, seems to be a promising biomarker, especially in view of the potential of Chironomus larvae as a biomonitoring species and of the physiological particularities of their respiratory pigments. (c) 2006 Elsevier Ltd. All rights reserved.","Expression of heat shock protein and hemoglobin genes in Chironomus tentans (Diptera, chironomidae) larvae exposed to various environmental pollutants: A potential biomarker of freshwater monitoring Abs: To identify a sensitive biomarker of freshwater monitoring, we evaluated pollutant-induced expression of heat shock proteins (HSPs) and hemoglobins (Hbs) genes in the larvae of the aquatic midge Chironomus tentans (Diptera, Chironomidae). As pollutants, we examined nonylphenol, bisphenol-A, 17 alpha-ethynyl estradiol, bis(2-ethylhexyl) phthalate, endosulfan, paraquat dichloride, chloropyriphos, fenitrothion, cadmium chloride, lead nitrate, potassium dichromate, benzo[a]pyrene and carbon tetrachloride. We also investigated larval growth as a physiological descriptor by measuring changes in the body fresh weight and dry weight after chemical exposure. The response of the HSPs gene expression by chemical exposure was rapid and sensitive to low chemical concentrations but it was not stressor specific. Interestingly, an increase in the expression of HSPs genes was observed not only in a stress inducible form (HSP70), but also in a constitutively (HSC70) expressed form. The expression of Hb genes showed chemical-specific responses: that is, alkyl phenolic compounds increased the expression of hemoglobin genes, whereas pesticides decreased the expression. As expected, molecular-level markers were more sensitive than physiological endpoints, suggesting that gene expression could be developed as an early warning biomarker in this animal. The overall results suggest that the expression of HSP and Hb genes in Chironomus could give useful information for diagnosing general health conditions in fresh water ecosystem. The expression of Hb genes, in particular, seems to be a promising biomarker, especially in view of the potential of Chironomus larvae as a biomonitoring species and of the physiological particularities of their respiratory pigments. (c) 2006 Elsevier Ltd. All rights reserved."
491239,Ladou and  Lovegrove 2008,Export of electronics equipment waste,"Electronics equipment waste (""e-waste"") includes discarded computers, computer monitors, television sets, and cell phones. Less than 10% of e-waste is currently recycled. The United States and other developed countries export e-waste primarily to Asia, knowing it carries a real harm to the poor communities where it will be discarded. A 2006 directive bans the use of lead, mercury, cadmium, hexavalent chromium, and certain brominated flame retardants in most electronics products sold in the EU. A similar directive facilitates the development and design of clean electronics products with longer lifespans that are safe and easy to repair, upgrade, and recycle, and will not expose workers and the environment to hazardous chemicals. These useful approaches apply only regionally and cover only a fraction of the hazardous substances used in electronics manufacture, however. There is an urgent need for manufacturers of electronics products to take responsibility for their products from production to end-of-life, and for much tighter controls both on the trans-boundary movement of e-waste and on the manner in which it is recycled. Manufacturers must develop clean products with longer lifespans that are safe and easy to repair, upgrade, and recycle and will not expose workers and the environment to hazardous chemicals.","Export of electronics equipment waste Abs: Electronics equipment waste (""e-waste"") includes discarded computers, computer monitors, television sets, and cell phones. Less than 10% of e-waste is currently recycled. The United States and other developed countries export e-waste primarily to Asia, knowing it carries a real harm to the poor communities where it will be discarded. A 2006 directive bans the use of lead, mercury, cadmium, hexavalent chromium, and certain brominated flame retardants in most electronics products sold in the EU. A similar directive facilitates the development and design of clean electronics products with longer lifespans that are safe and easy to repair, upgrade, and recycle, and will not expose workers and the environment to hazardous chemicals. These useful approaches apply only regionally and cover only a fraction of the hazardous substances used in electronics manufacture, however. There is an urgent need for manufacturers of electronics products to take responsibility for their products from production to end-of-life, and for much tighter controls both on the trans-boundary movement of e-waste and on the manner in which it is recycled. Manufacturers must develop clean products with longer lifespans that are safe and easy to repair, upgrade, and recycle and will not expose workers and the environment to hazardous chemicals."
491161,Labra et al. 2006,Zea mays L. protein changes in response to potassium dichromate treatments,"The plant metabolic response to heavy metal stress is largely unknown. The present investigation was undertaken to examine the influence of different concentrations of potassium dichromate on the Zea mays L. plantlets. A clear effect of chromium on maize plantlets growth and seed germination was observed strating from 100-300 ppm up to 1500 ppm. In this concentration range, chromium uptake was dependent on the concentration in the medium. Metallothioneins, involved in heavy metal binding, were measured by capillary electrophoresis (CE), and showed a dose-response induction. Protein profile analyzed by two-dimensional gel electrophoresis showed differential expression of several proteins. Identification of spots of upregulated proteins was performed by MALDI mass spectrometry. Results showed that proteins induced by heavy metal exposure are principally involved in oxidative stress tolerance or in other stress pathways. Induction of proteins implicated in sugar metabolism was also observed. Identification of factors involved in plant response may lead to a better understanding of the mechanisms involved in cell protection and tolerance. This information could be used to improve agricultural production and environmental quality. (c) 2005 Elsevier Ltd. All rights reserved.","Zea mays L. protein changes in response to potassium dichromate treatments Abs: The plant metabolic response to heavy metal stress is largely unknown. The present investigation was undertaken to examine the influence of different concentrations of potassium dichromate on the Zea mays L. plantlets. A clear effect of chromium on maize plantlets growth and seed germination was observed strating from 100-300 ppm up to 1500 ppm. In this concentration range, chromium uptake was dependent on the concentration in the medium. Metallothioneins, involved in heavy metal binding, were measured by capillary electrophoresis (CE), and showed a dose-response induction. Protein profile analyzed by two-dimensional gel electrophoresis showed differential expression of several proteins. Identification of spots of upregulated proteins was performed by MALDI mass spectrometry. Results showed that proteins induced by heavy metal exposure are principally involved in oxidative stress tolerance or in other stress pathways. Induction of proteins implicated in sugar metabolism was also observed. Identification of factors involved in plant response may lead to a better understanding of the mechanisms involved in cell protection and tolerance. This information could be used to improve agricultural production and environmental quality. (c) 2005 Elsevier Ltd. All rights reserved."
490982,Kuykendall et al. 2006,Waterborne and dietary hexavalent chromium exposure causes DNA-protein crosslink (DPX) formation in erythrocytes of largemouth bass (Micropterus salmoides),"Formation of DNA-protein crosslinks (DPXs) was demonstrated in erythrocytes from fathead minnows (Pimephales promelas) and largemouth bass (Micropterus salmoides) exposed to hexavalent chromium [Cr(VI)], a known carcinogenic and mutagenic metal contaminant of many industrial waterways. Tank water exposure of 2-3 in. fathead minnows to 2 ppm Cr(VI) led to significant DPX formation in erythrocytes, with over 140-200% elevations above background levels at 3-4 days, respectively. Largemouth bass exposed similarly were found to have 62% elevation of DPX levels after 4 days. When largemouth bass were fed a diet of minnows injected with 20 mu g Cr(VI) for 5 days, a significant (p < 0.01) increase of DPXs in erythrocytes was observed, with 80% elevation above erythrocytes from bass fed minnows injected only with saline. However, when largemouth bass were fed a diet exclusively of minnows exposed to 2 ppm Cr(VI) for 21 days, there was no significant difference in DPX levels compared to bass fed control (unexposed) minnows. This study provides evidence that DPX formation occurs in erythrocytes of fathead minnows exposed under controlled conditions to low ppm Cr(VI) concentrations, which is at or below concentrations previously assigned no observable effect levels. Furthermore, it appears that both waterborne and high dose dietary exposure to Cr(VI) can lead to DPX formation in erythrocytes of predatory fish species such as bass. However, it is unlikely that a bioconcentration of chromium in the food chain would be a major concern at these low ppm levels of exposure. Further, it may be difficult to achieve dietary Cr(VI) levels high enough to elicit DPXs in predatory fish under most environmental exposure scenarios. (c) 2006 Published by Elsevier B.V.","Waterborne and dietary hexavalent chromium exposure causes DNA-protein crosslink (DPX) formation in erythrocytes of largemouth bass (Micropterus salmoides) Abs: Formation of DNA-protein crosslinks (DPXs) was demonstrated in erythrocytes from fathead minnows (Pimephales promelas) and largemouth bass (Micropterus salmoides) exposed to hexavalent chromium [Cr(VI)], a known carcinogenic and mutagenic metal contaminant of many industrial waterways. Tank water exposure of 2-3 in. fathead minnows to 2 ppm Cr(VI) led to significant DPX formation in erythrocytes, with over 140-200% elevations above background levels at 3-4 days, respectively. Largemouth bass exposed similarly were found to have 62% elevation of DPX levels after 4 days. When largemouth bass were fed a diet of minnows injected with 20 mu g Cr(VI) for 5 days, a significant (p < 0.01) increase of DPXs in erythrocytes was observed, with 80% elevation above erythrocytes from bass fed minnows injected only with saline. However, when largemouth bass were fed a diet exclusively of minnows exposed to 2 ppm Cr(VI) for 21 days, there was no significant difference in DPX levels compared to bass fed control (unexposed) minnows. This study provides evidence that DPX formation occurs in erythrocytes of fathead minnows exposed under controlled conditions to low ppm Cr(VI) concentrations, which is at or below concentrations previously assigned no observable effect levels. Furthermore, it appears that both waterborne and high dose dietary exposure to Cr(VI) can lead to DPX formation in erythrocytes of predatory fish species such as bass. However, it is unlikely that a bioconcentration of chromium in the food chain would be a major concern at these low ppm levels of exposure. Further, it may be difficult to achieve dietary Cr(VI) levels high enough to elicit DPXs in predatory fish under most environmental exposure scenarios. (c) 2006 Published by Elsevier B.V."
490717,Kumpiene et al. 2008,"Stabilization of As, Cr, Cu, Pb and Zn in soil using amendments - A review","The spread of contaminants in soil can be hindered by the soil stabilization technique. Contaminant immobilizing amendments decrease trace element leaching and their bioavailability by inducing various sorption processes: adsorption to mineral surfaces, formation of stable complexes with organic ligands, surface precipitation and ion exchange. Precipitation as salts and co-precipitation can also contribute to reducing contaminant mobility. The technique can be used in in situ and ex situ applications to reclaim and re-vegetate industrially devastated areas and mine-spoils, improve soil quality and reduce contaminant mobility by stabilizing agents and a beneficial use of industrial by-products. This study is an overview of data published during the last five years on the immobilization of one metalloid, As, and four heavy metals, Cr, Cu, Pb and Zn, in soils. The most extensively studied amendments for As immobilization are Fe containing materials. The immobilization of As occurs through adsorption on Fe oxides by replacing the surface hydroxyl groups with the As ions, as well as by the formation of amorphous Fe(III) arsenates and/or insoluble secondary oxidation minerals. Cr stabilization mainly deals with Cr reduction from its toxic and mobile hexavalent form Cr(VI) to stable in natural environments Cr(III). The reduction is accelerated in soil by the presence of organic matter and divalent iron. Clays, carbonates, phosphates and Fe oxides were the common amendments tested for Cu immobilization. The suggested mechanisms of Cu retention were precipitation of Cu carbonates and oxyhydroxides, ion exchange and formation of ternary cation-anion complexes on the surface of Fe and Al oxy-hydroxides. Most of the studies on Pb stabilization were performed using various phosphorus-containing amendments, which reduce the Pb mobility by ionic exchange and precipitation of pyromorphite-type minerals. Zn can be successfully immobilized in soil by phosphorus amendments and clays. (c) 2007 Elsevier Ltd. All rights reserved.","Stabilization of As, Cr, Cu, Pb and Zn in soil using amendments - A review Abs: The spread of contaminants in soil can be hindered by the soil stabilization technique. Contaminant immobilizing amendments decrease trace element leaching and their bioavailability by inducing various sorption processes: adsorption to mineral surfaces, formation of stable complexes with organic ligands, surface precipitation and ion exchange. Precipitation as salts and co-precipitation can also contribute to reducing contaminant mobility. The technique can be used in in situ and ex situ applications to reclaim and re-vegetate industrially devastated areas and mine-spoils, improve soil quality and reduce contaminant mobility by stabilizing agents and a beneficial use of industrial by-products. This study is an overview of data published during the last five years on the immobilization of one metalloid, As, and four heavy metals, Cr, Cu, Pb and Zn, in soils. The most extensively studied amendments for As immobilization are Fe containing materials. The immobilization of As occurs through adsorption on Fe oxides by replacing the surface hydroxyl groups with the As ions, as well as by the formation of amorphous Fe(III) arsenates and/or insoluble secondary oxidation minerals. Cr stabilization mainly deals with Cr reduction from its toxic and mobile hexavalent form Cr(VI) to stable in natural environments Cr(III). The reduction is accelerated in soil by the presence of organic matter and divalent iron. Clays, carbonates, phosphates and Fe oxides were the common amendments tested for Cu immobilization. The suggested mechanisms of Cu retention were precipitation of Cu carbonates and oxyhydroxides, ion exchange and formation of ternary cation-anion complexes on the surface of Fe and Al oxy-hydroxides. Most of the studies on Pb stabilization were performed using various phosphorus-containing amendments, which reduce the Pb mobility by ionic exchange and precipitation of pyromorphite-type minerals. Zn can be successfully immobilized in soil by phosphorus amendments and clays. (c) 2007 Elsevier Ltd. All rights reserved."
488090,Kiptoo and  Ngila 2005,"Voltammetric evaluation of binding abilities of tannery effluents by competing ligand exchange method using model solutions of Cr(VI), Ni(II), Cu(II) and Pb(II)","Metal complexation capacity (CC) is an important parameter in assessing the quality of wastewaters. In this study, CC and complexation kinetics of tannery wastewater was evaluated using the competing ligand exchange approach with model solutions of Cr(VI), Ni(II), Cu(II) and Pb(II). Ethylenediaminetetraactic acid (EDTA) was used as competing ligand in complexation studies of Cu and Pb while dimethylglyoxime (DMG) and cliethylenetriaminepentaacetic acid (DTPA) were used in the case of Ni and Cr, respectively. Determination of labile metal fraction was done using differential pulse anodic stripping voltammetry (DPASV) (Cu and Pb) and differential pulse adsorptive cathodic stripping voltammetry (DPAdCSV) (Ni and Cr) at a hanging mercury drop electrode (HMDE). Flame atomic absorption spectrophotometry (FAAS) was used to determine total and dissolved chromium in the tannery wastewater samples. Results show high complexation capacities (9.03-436.81 mu M) and fast kinetics of the tannery effluent, with most of the inert metal species being formed within the first two minutes. The kinetic curves for all the metals showed two kinetically distinguishable components, except for nickel which had an extra component. Speciation results revealed that less than 3% of the chromium in the wastewater was present in the dissolved phase, while no labile forms were detected. The study has demonstrated the role of CC of wastewater in metal speciation and environmental remediation.","Voltammetric evaluation of binding abilities of tannery effluents by competing ligand exchange method using model solutions of Cr(VI), Ni(II), Cu(II) and Pb(II) Abs: Metal complexation capacity (CC) is an important parameter in assessing the quality of wastewaters. In this study, CC and complexation kinetics of tannery wastewater was evaluated using the competing ligand exchange approach with model solutions of Cr(VI), Ni(II), Cu(II) and Pb(II). Ethylenediaminetetraactic acid (EDTA) was used as competing ligand in complexation studies of Cu and Pb while dimethylglyoxime (DMG) and cliethylenetriaminepentaacetic acid (DTPA) were used in the case of Ni and Cr, respectively. Determination of labile metal fraction was done using differential pulse anodic stripping voltammetry (DPASV) (Cu and Pb) and differential pulse adsorptive cathodic stripping voltammetry (DPAdCSV) (Ni and Cr) at a hanging mercury drop electrode (HMDE). Flame atomic absorption spectrophotometry (FAAS) was used to determine total and dissolved chromium in the tannery wastewater samples. Results show high complexation capacities (9.03-436.81 mu M) and fast kinetics of the tannery effluent, with most of the inert metal species being formed within the first two minutes. The kinetic curves for all the metals showed two kinetically distinguishable components, except for nickel which had an extra component. Speciation results revealed that less than 3% of the chromium in the wastewater was present in the dissolved phase, while no labile forms were detected. The study has demonstrated the role of CC of wastewater in metal speciation and environmental remediation."
486411,Katiyar et al. 2008,Suppression of IL-6 level in human peripheral blood mononuclear cells stimulated with PHA/LPS after occupational exposure to chromium,"The toxic metals alter the immune response of animals as well as humans. In addition to the well documented and numerous toxic effect of chromium on various target organs, number of studies shown that acute and chronic exposure to inorganic chromium may result in impairment of immune functions in the experimental systems. Immunosuppression appears to be more subtle effect of exposure to heavy metals. Therefore, we have taken two different groups of chromium exposed individuals. These were leather tanning workers and chromeplaters. These groups of individuals were regularly exposed to chromium. All the leather tanning workers were highly exposed to chromium having a mean of 96.60 113.95 mg/dl (range 12.4-417.21 mg/dl). A suspension of exposed and unexposed human PBMC (0.5 X 106 cells/ml) prepared and cultured in RPMI-1640 supplemented with 10% FCS for 18 h in the presence or absence of PHA (5 mu g/ml) and LPS (10 ng/ml) which used for stimulation of IL-2, IL-4, TNF-alpha, IL-10 and IL-6, respectively. The levels of Th1/Th2 cytokine: IL-2, IL-4, TNF-alpha, IL-10 and IL-6 were evaluated in the sera and PHA/LPS stimulated culture supernatant of human PBMCs of chromium exposed workers. in these workers the level of IL-6 was 543.95 +/- 123.75 pg/ml and 388.40 +/- 61.24 pg/ml in PHA/LPS stimulated culture supernatant of normal individuals and highly chromium exposed workers, which was significant (P<0.05). This observation suggests that IL-6 levels were suppressed in chromium exposed groups as compared to unexposed healthy volunteers. Although the level of IL-2 in PHA stimulated culture supernatant of PBMCs was suppressed in chromium exposed individuals but it was not significant, IL-4 and IL-10 could not be detected. However, there was no difference in TNF-alpha levels in sera samples as well as unstimulated culture supernatant of h-PBMCs of chromium exposed individuals as compared to control. (c) 2007 Elsevier B.V. All rights reserved.","Suppression of IL-6 level in human peripheral blood mononuclear cells stimulated with PHA/LPS after occupational exposure to chromium Abs: The toxic metals alter the immune response of animals as well as humans. In addition to the well documented and numerous toxic effect of chromium on various target organs, number of studies shown that acute and chronic exposure to inorganic chromium may result in impairment of immune functions in the experimental systems. Immunosuppression appears to be more subtle effect of exposure to heavy metals. Therefore, we have taken two different groups of chromium exposed individuals. These were leather tanning workers and chromeplaters. These groups of individuals were regularly exposed to chromium. All the leather tanning workers were highly exposed to chromium having a mean of 96.60 113.95 mg/dl (range 12.4-417.21 mg/dl). A suspension of exposed and unexposed human PBMC (0.5 X 106 cells/ml) prepared and cultured in RPMI-1640 supplemented with 10% FCS for 18 h in the presence or absence of PHA (5 mu g/ml) and LPS (10 ng/ml) which used for stimulation of IL-2, IL-4, TNF-alpha, IL-10 and IL-6, respectively. The levels of Th1/Th2 cytokine: IL-2, IL-4, TNF-alpha, IL-10 and IL-6 were evaluated in the sera and PHA/LPS stimulated culture supernatant of human PBMCs of chromium exposed workers. in these workers the level of IL-6 was 543.95 +/- 123.75 pg/ml and 388.40 +/- 61.24 pg/ml in PHA/LPS stimulated culture supernatant of normal individuals and highly chromium exposed workers, which was significant (P<0.05). This observation suggests that IL-6 levels were suppressed in chromium exposed groups as compared to unexposed healthy volunteers. Although the level of IL-2 in PHA stimulated culture supernatant of PBMCs was suppressed in chromium exposed individuals but it was not significant, IL-4 and IL-10 could not be detected. However, there was no difference in TNF-alpha levels in sera samples as well as unstimulated culture supernatant of h-PBMCs of chromium exposed individuals as compared to control. (c) 2007 Elsevier B.V. All rights reserved."
485301,Kaczmarek et al. 2007,The role of ascorbate in the modulation of HIF-1 alpha protein and HIF-dependent transcription by chromium(VI) and nickel(II),"Molecular oxygen is involved in hydroxylation and subsequent degradation of HIF-1 alpha, a subunit of HIF-1 transcription factor; therefore oxygen shortage (hypoxia) stabilizes this protein. However, HIF-1 alpha can also be stabilized by transition metal ions in the presence of oxygen, suggesting that a different mechanism is involved in metal-induced hypoxic stress. Recently, we showed that the depletion of intracellular ascorbate by metals may lead to the inhibition of hydroxylases. Because nickel(II) has similarity to iron(II), an alternative hypothesis suggests that iron substitution for nickel in the enzyme inhibits hydroxylase activity. Here we investigated the induction of HIF-1 by another metal, chromium, which cannot replace iron in the enzyme. We show that chromium(VI), but not chromium(III), can oxidize ascorbate both in cells and in a cell-free system. In agreement with these data chromium(VI) stabilizes HIF-1 alpha protein in cells only until it is reduced to chromium(III). In contrast, nickel (II) was found to be a catalyst, which facilitated continuous oxidation of ascorbate by ambient oxygen. These data correlate with extended stabilization of HIF-1 alpha after acute exposur to nickel(II). The HIF-1-dependent reporter assays revealed that 20-24 h was required to fully develop the HIF-1 transcriptional response, and the acute exposure to nickel(II), but not chromium(VI), meets this requirement. However, repeated (chronic) exposure to chromium(VI) can also lead to extended stabilization of HIF-1 alpha. Thus, the obtained data emphasize the important role of ascorbate in regulation of HIF-1 transcriptional activity in metal-exposed human lung cells. Published by Elsevier Inc.","The role of ascorbate in the modulation of HIF-1 alpha protein and HIF-dependent transcription by chromium(VI) and nickel(II) Abs: Molecular oxygen is involved in hydroxylation and subsequent degradation of HIF-1 alpha, a subunit of HIF-1 transcription factor; therefore oxygen shortage (hypoxia) stabilizes this protein. However, HIF-1 alpha can also be stabilized by transition metal ions in the presence of oxygen, suggesting that a different mechanism is involved in metal-induced hypoxic stress. Recently, we showed that the depletion of intracellular ascorbate by metals may lead to the inhibition of hydroxylases. Because nickel(II) has similarity to iron(II), an alternative hypothesis suggests that iron substitution for nickel in the enzyme inhibits hydroxylase activity. Here we investigated the induction of HIF-1 by another metal, chromium, which cannot replace iron in the enzyme. We show that chromium(VI), but not chromium(III), can oxidize ascorbate both in cells and in a cell-free system. In agreement with these data chromium(VI) stabilizes HIF-1 alpha protein in cells only until it is reduced to chromium(III). In contrast, nickel (II) was found to be a catalyst, which facilitated continuous oxidation of ascorbate by ambient oxygen. These data correlate with extended stabilization of HIF-1 alpha after acute exposur to nickel(II). The HIF-1-dependent reporter assays revealed that 20-24 h was required to fully develop the HIF-1 transcriptional response, and the acute exposure to nickel(II), but not chromium(VI), meets this requirement. However, repeated (chronic) exposure to chromium(VI) can also lead to extended stabilization of HIF-1 alpha. Thus, the obtained data emphasize the important role of ascorbate in regulation of HIF-1 transcriptional activity in metal-exposed human lung cells. Published by Elsevier Inc."
482809,Ipsilantis and  Coyne 2007,Soil microbial community response to hexavalent chromium in planted and unplanted soil,"Theories suggest that rapid microbial growth rates lead to quicker development of metal resistance. We tested these theories by adding hexavalent chromium [Cr(VI)] to soil, sowing Indian mustard (Brassica juncea), and comparing rhizosphere and bulk soil microbial community responses. Four weeks after the initial Cr(VI) application we measured Cr concentration, microbial biomass by fumigation extraction and soil extract ATP, tolerance to Cr and growth rates with tritiated thymidine incorporation, and performed community substrate use analysis with BIOLOG GN plates. Exchangeable Cr(VI) levels were very low, and therefore we assumed the Cr(VI) impact was transient. Microbial biomass was reduced by Cr(VI) addition. Microbial tolerance to Cr(VI) tended to be higher in the Cr-treated rhizosphere soil relative to the non-treated systems, while microorganisms in the Cr-treated bulk soil were less sensitive to Cr(VI) than microorganisms in the non-treated bulk soil. Microbial diversity as measured by population evenness increased with Cr(VI) addition based on a Gini coefficient derived from BIOLOG substrate use patterns. Principal component analysis revealed separation between Cr(VI) treatments, and between rhizosphere and bulk soil treatments. We hypothesize that because of Cr(VI) addition there was indirect selection for fast growing organisms, alleviation of competition among microbial communities, and increase in Cr tolerance in the rhizosphere due to the faster turnover rates in that environment.","Soil microbial community response to hexavalent chromium in planted and unplanted soil Abs: Theories suggest that rapid microbial growth rates lead to quicker development of metal resistance. We tested these theories by adding hexavalent chromium [Cr(VI)] to soil, sowing Indian mustard (Brassica juncea), and comparing rhizosphere and bulk soil microbial community responses. Four weeks after the initial Cr(VI) application we measured Cr concentration, microbial biomass by fumigation extraction and soil extract ATP, tolerance to Cr and growth rates with tritiated thymidine incorporation, and performed community substrate use analysis with BIOLOG GN plates. Exchangeable Cr(VI) levels were very low, and therefore we assumed the Cr(VI) impact was transient. Microbial biomass was reduced by Cr(VI) addition. Microbial tolerance to Cr(VI) tended to be higher in the Cr-treated rhizosphere soil relative to the non-treated systems, while microorganisms in the Cr-treated bulk soil were less sensitive to Cr(VI) than microorganisms in the non-treated bulk soil. Microbial diversity as measured by population evenness increased with Cr(VI) addition based on a Gini coefficient derived from BIOLOG substrate use patterns. Principal component analysis revealed separation between Cr(VI) treatments, and between rhizosphere and bulk soil treatments. We hypothesize that because of Cr(VI) addition there was indirect selection for fast growing organisms, alleviation of competition among microbial communities, and increase in Cr tolerance in the rhizosphere due to the faster turnover rates in that environment."
482254,Hutchinson et al. 2007,Identification of inorganic improvised explosive devices by analysis of postblast residues using portable capillary electrophoresis instrumentation and indirect photometric detection with a light-emitting diode,"A commercial portable capillary electrophoresis (CE) instrument has been used to separate inorganic anions and cations found in postblast residues from improvised explosive devices (IEDs) of the type used frequently in terrorism attacks. The purpose of this analysis was to identify the type of explosive used. The CE instrument was modified for use with an in-house miniaturized light-emitting diode (LED) detector to enable sensitive indirect photometric detection to be employed for the detection of 15 anions (acetate, benzoate, carbonate, chlorate, chloride, chlorite, cyanate, fluoride, nitrate, nitrite, perchlorate, phosphate, sulfate, thiocyanate, thiosulfate) and 12 cations (ammonium, monomethylammonium, ethylammonium, potassium, sodium, barium, strontium, magnesium, manganese, calcium, zinc, lead) as the target analytes. These ions are known to be present in postblast residues from inorganic IEDs constructed from ammonium nitrate/fuel oil mixtures, black powder, and chlorate/perchlorate/sugar mixtures. For the analysis of cations, a blue LED (470 nm) was used in conjunction with the highly absorbing cationic dye, chrysoidine (absorption maximum at 453 rim). A nonaqueous background electrolyte comprising 10 mM chrysoidine in methanol was found to give greatly improved baseline stability in comparison to aqueous electrolytes due to the increased solubility of chrysoidine and its decreased adsorption onto the capillary, wall. Glacial acetic acid (0.7% v/v) was added to ensure chrysoidine was protonated and to enhance separation selectivity by means of complexation with transition metal ions. The 12 target cations were separated in less than 9.5 min with detection limits of 0.11-2.30 mg/L (calculated at a signal-to-noise ratio of 3). The anions separation system utilized a UV LED (370 nm) in conjunction with an aqueous chromate electrolyte (absorption maximum at 371 nm) consisting of 10 mM chromium(VI) oxide and 10 mM sodium chromate, buffered with 40 mM tris(hydroxymethyl)aminomethane at pH 8.05. All 15 target anions were baseline separated in less than 9 min with limits of detection ranging from 0.24 to 1.15 mg/L (calculated at a signal-to-noise ratio of 3). Use of the portable instrumentation in the field was demonstrated by analyzing postblast residues in a mobile laboratory immediately after detonation of the explosive devices. Profiling the ionic composition of the inorganic IEDs allowed identification of the chemicals used in their construction.","Identification of inorganic improvised explosive devices by analysis of postblast residues using portable capillary electrophoresis instrumentation and indirect photometric detection with a light-emitting diode Abs: A commercial portable capillary electrophoresis (CE) instrument has been used to separate inorganic anions and cations found in postblast residues from improvised explosive devices (IEDs) of the type used frequently in terrorism attacks. The purpose of this analysis was to identify the type of explosive used. The CE instrument was modified for use with an in-house miniaturized light-emitting diode (LED) detector to enable sensitive indirect photometric detection to be employed for the detection of 15 anions (acetate, benzoate, carbonate, chlorate, chloride, chlorite, cyanate, fluoride, nitrate, nitrite, perchlorate, phosphate, sulfate, thiocyanate, thiosulfate) and 12 cations (ammonium, monomethylammonium, ethylammonium, potassium, sodium, barium, strontium, magnesium, manganese, calcium, zinc, lead) as the target analytes. These ions are known to be present in postblast residues from inorganic IEDs constructed from ammonium nitrate/fuel oil mixtures, black powder, and chlorate/perchlorate/sugar mixtures. For the analysis of cations, a blue LED (470 nm) was used in conjunction with the highly absorbing cationic dye, chrysoidine (absorption maximum at 453 rim). A nonaqueous background electrolyte comprising 10 mM chrysoidine in methanol was found to give greatly improved baseline stability in comparison to aqueous electrolytes due to the increased solubility of chrysoidine and its decreased adsorption onto the capillary, wall. Glacial acetic acid (0.7% v/v) was added to ensure chrysoidine was protonated and to enhance separation selectivity by means of complexation with transition metal ions. The 12 target cations were separated in less than 9.5 min with detection limits of 0.11-2.30 mg/L (calculated at a signal-to-noise ratio of 3). The anions separation system utilized a UV LED (370 nm) in conjunction with an aqueous chromate electrolyte (absorption maximum at 371 nm) consisting of 10 mM chromium(VI) oxide and 10 mM sodium chromate, buffered with 40 mM tris(hydroxymethyl)aminomethane at pH 8.05. All 15 target anions were baseline separated in less than 9 min with limits of detection ranging from 0.24 to 1.15 mg/L (calculated at a signal-to-noise ratio of 3). Use of the portable instrumentation in the field was demonstrated by analyzing postblast residues in a mobile laboratory immediately after detonation of the explosive devices. Profiling the ionic composition of the inorganic IEDs allowed identification of the chemicals used in their construction."
480854,Hong et al. 2008,Luminescent and magnetic Fe3O4/Py/PAM nanocomposites for the chromium(VI) determination,"A novel luminescent and magnetic Fe3O4/pyrene/polyacrylamide (Fe3O4/Py/PAM) nanocomposite has been prepared under ultrasonic radiation. This magnetic nanocomposite combined with pyrene would lead to a special functional magnetic luminescent composite that enjoys both the advantages of magnetic nanoparticles of Fe3O4 and fluorescence nanoparticles of pyrene. Taking advantage of the magnetic property of Fe3O4 nanocomposites, we can separate Fe3O4/Py/PAM nanocomposites from solution easily just by using a permanent magnet. Based on the fluorescence quenching of Fe3O4/Py/PAM nanocomposites by Cr(VI), a method for the selective determination of Cr(VI), without separation of Cr(III) in water, was developed. Under optimal experimental conditions, a limit of detection of 0.01 mu g mL(-1) was achieved. The calibration curve was linear over the concentration range of 0.1-14.0 mu g mL(-1) with a correlation coefficient of 0.9975. The proposed method has been applied to the selective quantification of Cr(VI) in synthetic samples and wastewater samples with the satisfactory results. (C) 2008 Elsevier B.V. All rights reserved.","Luminescent and magnetic Fe3O4/Py/PAM nanocomposites for the chromium(VI) determination Abs: A novel luminescent and magnetic Fe3O4/pyrene/polyacrylamide (Fe3O4/Py/PAM) nanocomposite has been prepared under ultrasonic radiation. This magnetic nanocomposite combined with pyrene would lead to a special functional magnetic luminescent composite that enjoys both the advantages of magnetic nanoparticles of Fe3O4 and fluorescence nanoparticles of pyrene. Taking advantage of the magnetic property of Fe3O4 nanocomposites, we can separate Fe3O4/Py/PAM nanocomposites from solution easily just by using a permanent magnet. Based on the fluorescence quenching of Fe3O4/Py/PAM nanocomposites by Cr(VI), a method for the selective determination of Cr(VI), without separation of Cr(III) in water, was developed. Under optimal experimental conditions, a limit of detection of 0.01 mu g mL(-1) was achieved. The calibration curve was linear over the concentration range of 0.1-14.0 mu g mL(-1) with a correlation coefficient of 0.9975. The proposed method has been applied to the selective quantification of Cr(VI) in synthetic samples and wastewater samples with the satisfactory results. (C) 2008 Elsevier B.V. All rights reserved."
480707,Holmes et al. 2008,Carcinogenicity of hexavalent chromium,"Hexavalent chromium (Cr(VI)), a commonly used industrial metal, is a well known human lung carcinogen. Epidemiology and animal studies suggest that the particulate Cr(VI) compounds, specifically the water insoluble compounds, are the more potent carcinogens, however, the carcinogenic mechanism remains unknown. Here we summarize recent Cr(VI)-induced human tumour, in vivo, cell culture and in vitro studies and put the data into context with three major paradigms of carcinogenesis: multistage carcinogenesis, genomic instability, and epigenetic modifications. Based on these studies, we propose a mechanism for chromate carcinogenesis that is primarily driven by the genomic instability paradigm.","Carcinogenicity of hexavalent chromium Abs: Hexavalent chromium (Cr(VI)), a commonly used industrial metal, is a well known human lung carcinogen. Epidemiology and animal studies suggest that the particulate Cr(VI) compounds, specifically the water insoluble compounds, are the more potent carcinogens, however, the carcinogenic mechanism remains unknown. Here we summarize recent Cr(VI)-induced human tumour, in vivo, cell culture and in vitro studies and put the data into context with three major paradigms of carcinogenesis: multistage carcinogenesis, genomic instability, and epigenetic modifications. Based on these studies, we propose a mechanism for chromate carcinogenesis that is primarily driven by the genomic instability paradigm."
480706,Holmes et al. 2006,The clastogenic effects of chronic exposure to particulate and soluble Cr(VI) in human lung cells,"Hexavalent chromium (Cr(VI)) is a well-designated human lung carcinogen, with solubility playing an important role in its carcinogenic potential. Although it is known that particulate or water-insoluble Cr(VI) compounds are more potent than the soluble species of this metal, the mechanisms of action are not fully elucidated. In this study, we investigated the hypothesis that the difference in potency between particulate and soluble Cr(VI) is due to more chronic exposures with particulate chromate because it can deposit and persist in the lungs while soluble chromate is rapidly cleared. Chronic exposure to both insoluble lead chromate and soluble sodium chromate induced a concentration and time-dependent increase in intracellular Cr ion concentrations in cultured human lung fibroblasts. Intracellular Pb levels after chronic exposure to lead chromate increased in a concentration-dependent manner but did not increase with longer exposure times up to 72 h. We also investigated the effects of chronic exposure to Cr(VI) on clastogenicity and found that chronic exposure to lead chromate induces persistent or increasing chromosome damage. Specifically, exposure to 0.5 mu g/cm(2) lead chromate for 24, 48 and 72 h induced 23, 23 and 27% damaged metaphases, respectively. Contrary to lead chromate, the amount of chromosome damage after chronic exposure to sodium chromate decreased with time. For example, cells exposed to 1 mu M sodium chromate for 24, 48 and 72 h induced 23, 13 and 17% damaged metaphases, respectively. Our data suggest a possible mechanism for the observed potency difference between soluble and insoluble Cr(VI) compounds is that chronic exposure to particulate Cr(VI) induces persistent chromosome damage and chromosome instability while chromosome damage is repaired with chronic exposure to soluble Cr(VI). (c) 2006 Elsevier B.V. All rights reserved.","The clastogenic effects of chronic exposure to particulate and soluble Cr(VI) in human lung cells Abs: Hexavalent chromium (Cr(VI)) is a well-designated human lung carcinogen, with solubility playing an important role in its carcinogenic potential. Although it is known that particulate or water-insoluble Cr(VI) compounds are more potent than the soluble species of this metal, the mechanisms of action are not fully elucidated. In this study, we investigated the hypothesis that the difference in potency between particulate and soluble Cr(VI) is due to more chronic exposures with particulate chromate because it can deposit and persist in the lungs while soluble chromate is rapidly cleared. Chronic exposure to both insoluble lead chromate and soluble sodium chromate induced a concentration and time-dependent increase in intracellular Cr ion concentrations in cultured human lung fibroblasts. Intracellular Pb levels after chronic exposure to lead chromate increased in a concentration-dependent manner but did not increase with longer exposure times up to 72 h. We also investigated the effects of chronic exposure to Cr(VI) on clastogenicity and found that chronic exposure to lead chromate induces persistent or increasing chromosome damage. Specifically, exposure to 0.5 mu g/cm(2) lead chromate for 24, 48 and 72 h induced 23, 23 and 27% damaged metaphases, respectively. Contrary to lead chromate, the amount of chromosome damage after chronic exposure to sodium chromate decreased with time. For example, cells exposed to 1 mu M sodium chromate for 24, 48 and 72 h induced 23, 13 and 17% damaged metaphases, respectively. Our data suggest a possible mechanism for the observed potency difference between soluble and insoluble Cr(VI) compounds is that chronic exposure to particulate Cr(VI) induces persistent chromosome damage and chromosome instability while chromosome damage is repaired with chronic exposure to soluble Cr(VI). (c) 2006 Elsevier B.V. All rights reserved."
480705,Holmes et al. 2006,Chronic exposure to lead chromate causes centrosome abnormalities and aneuploidy in human lung cells,"Hexavalent chromium [Cr(Art)] compounds are established human lung carcinogens. The carcinogenicity of Cr(VI) is related to its solubility, with the most potent carcinogens being the insoluble particulate Cr(VI) compounds. However, it remains unknown why particulate Cr(VI) is more carcinogenic than soluble Cr(VI). One possible explanation is that particulates may provide more chronic exposures to chromate over time. We found that aneuploid cells increased in a concentration- and time-dependent manner after chronic exposure to lead chromate. Specificatly, a 24-hour lead chromate exposure induced no aneugenic effect, whereas a 120-hour exposure to 0.5 and 1 mu g/cm(2) lead chromate induced 55% and 60% aneuploid metaphases, respectively. We also found that many of these aneuploid cells were able to continue to grow and form colonies. Centrosome defects are known to induce aneuploidy; therefore, we investigated the effects of chronic lead chromate exposure on centrosomes. We found that centrosome amplification in interphase and mitotic cells increased in a concentration- and time-dependent manner with 0.5 and 1 mu g/cm(2) lead chromate for 120 hours, inducing aberrant centrosomes in 18% and 21% of interphase cells and 32% and 69% of mitotic cells, respectively; however, lead oxide did not induce centrosome amplification in interphase or mitotic cells. There was also an increase in aberrant mitosis after chronic exposure to lead chromate with the emergence of disorganized anaphase and mitotic catastrophe. These data suggest that one possible mechanism for lead chromate-induced carcinogenesis is through centrosome dysfunction, leading to the induction of aneuploidy.","Chronic exposure to lead chromate causes centrosome abnormalities and aneuploidy in human lung cells Abs: Hexavalent chromium [Cr(Art)] compounds are established human lung carcinogens. The carcinogenicity of Cr(VI) is related to its solubility, with the most potent carcinogens being the insoluble particulate Cr(VI) compounds. However, it remains unknown why particulate Cr(VI) is more carcinogenic than soluble Cr(VI). One possible explanation is that particulates may provide more chronic exposures to chromate over time. We found that aneuploid cells increased in a concentration- and time-dependent manner after chronic exposure to lead chromate. Specificatly, a 24-hour lead chromate exposure induced no aneugenic effect, whereas a 120-hour exposure to 0.5 and 1 mu g/cm(2) lead chromate induced 55% and 60% aneuploid metaphases, respectively. We also found that many of these aneuploid cells were able to continue to grow and form colonies. Centrosome defects are known to induce aneuploidy; therefore, we investigated the effects of chronic lead chromate exposure on centrosomes. We found that centrosome amplification in interphase and mitotic cells increased in a concentration- and time-dependent manner with 0.5 and 1 mu g/cm(2) lead chromate for 120 hours, inducing aberrant centrosomes in 18% and 21% of interphase cells and 32% and 69% of mitotic cells, respectively; however, lead oxide did not induce centrosome amplification in interphase or mitotic cells. There was also an increase in aberrant mitosis after chronic exposure to lead chromate with the emergence of disorganized anaphase and mitotic catastrophe. These data suggest that one possible mechanism for lead chromate-induced carcinogenesis is through centrosome dysfunction, leading to the induction of aneuploidy."
477228,Ha and  Choi 2008,"Effects of environmental contaminants on hemoglobin of larvae of aquatic midge, Chironomus riparius (Diptera : Chironomidae): A potential biomarker for ecotoxicity monitoring","The effects of environmental contaminants (i.e., nonylphenol, bisphenol A diglycidyl ether, benzo[a]pyrene, chlorpyriphos, paraquat dichloride, and lead nitrate) on Chironomus hemoglobin were investigated in the 4th instar larvae of Chironomus riparius (Diptera: Chironomidae), with respect to the total hemoglobin contents, individual globin gene expression, individual globin protein expression and hemoglobin oxidation. In our studies, 7 and 6 globin isoforms were preliminarily characterized by molecular weight and isoelectric point, respectively, in the 4th instar larvae of C riparius. Most chemicals were unable to modify the total hemoglobin contents, however, the expression patterns of the globin transcript and proteins suggest that C riparius globin exists in both inducible and consecutively expressed forms, with multiplicity that may allow this animal to better adapt toward stressful environmental conditions, including pollution stress. The oxyhemoglobin was observed to be downregulated in C riparius on exposure to bisphenol A and chlorpyriphos, probably reflecting its increased autoxidation to methemoglobin. The overall results would suggest that globin can be a target molecule of environmental contaminants, and of the tested parameters, the alteration of individual globin levels (i.e., mRNA or protein levels) may have potential for the development of a biomarker for ecotoxicity monitoring. (c) 2008 Elsevier Ltd. All rights reserved.","Effects of environmental contaminants on hemoglobin of larvae of aquatic midge, Chironomus riparius (Diptera : Chironomidae): A potential biomarker for ecotoxicity monitoring Abs: The effects of environmental contaminants (i.e., nonylphenol, bisphenol A diglycidyl ether, benzo[a]pyrene, chlorpyriphos, paraquat dichloride, and lead nitrate) on Chironomus hemoglobin were investigated in the 4th instar larvae of Chironomus riparius (Diptera: Chironomidae), with respect to the total hemoglobin contents, individual globin gene expression, individual globin protein expression and hemoglobin oxidation. In our studies, 7 and 6 globin isoforms were preliminarily characterized by molecular weight and isoelectric point, respectively, in the 4th instar larvae of C riparius. Most chemicals were unable to modify the total hemoglobin contents, however, the expression patterns of the globin transcript and proteins suggest that C riparius globin exists in both inducible and consecutively expressed forms, with multiplicity that may allow this animal to better adapt toward stressful environmental conditions, including pollution stress. The oxyhemoglobin was observed to be downregulated in C riparius on exposure to bisphenol A and chlorpyriphos, probably reflecting its increased autoxidation to methemoglobin. The overall results would suggest that globin can be a target molecule of environmental contaminants, and of the tested parameters, the alteration of individual globin levels (i.e., mRNA or protein levels) may have potential for the development of a biomarker for ecotoxicity monitoring. (c) 2008 Elsevier Ltd. All rights reserved."
477051,Gupta et al. 2006,The comparative effects of metals on the hatching of earthworm cocoons,"To establish the use of Metaphire posthuma as a sensitive model for ecotoxicological studies, the comparative effects of five metals on the hatching profiles of the cocoons of the earthworms, Metaphire posthuma, Eisenia foetida and Perionyx excavatus, were studied. The cocoons of the three species of earthworms were exposed to copper, chromium (III), chromium (VI), lead and zinc at 1.25, 2.5, 5.0 and 10.0ppm. Viable cocoons were incubated at 20 +/- 1 degrees C by using the immersion method. The results indicated that the inhibition of cocoon hatching was concentration dependent. The normal hatching, delayed hatching and non-viability of cocoons were recorded. At a concentration of 1.25ppm, there was almost no effect on the hatching of the cocoons of all three species of earthworms, except when exposed to chromium (VI), but higher concentrations (2.5 and 5.0ppm) caused severe effects. It was concluded that M. posthuma was more sensitive than the other two species, and that it is a suitable model for use in ecotoxicity testing.","The comparative effects of metals on the hatching of earthworm cocoons Abs: To establish the use of Metaphire posthuma as a sensitive model for ecotoxicological studies, the comparative effects of five metals on the hatching profiles of the cocoons of the earthworms, Metaphire posthuma, Eisenia foetida and Perionyx excavatus, were studied. The cocoons of the three species of earthworms were exposed to copper, chromium (III), chromium (VI), lead and zinc at 1.25, 2.5, 5.0 and 10.0ppm. Viable cocoons were incubated at 20 +/- 1 degrees C by using the immersion method. The results indicated that the inhibition of cocoon hatching was concentration dependent. The normal hatching, delayed hatching and non-viability of cocoons were recorded. At a concentration of 1.25ppm, there was almost no effect on the hatching of the cocoons of all three species of earthworms, except when exposed to chromium (VI), but higher concentrations (2.5 and 5.0ppm) caused severe effects. It was concluded that M. posthuma was more sensitive than the other two species, and that it is a suitable model for use in ecotoxicity testing."
476376,Gruber et al. 2008,Physiological responses of Juncus effusus (rush) to chromium and relevance for wastewater treatment in constructed wetlands,"Constructed wetlands are increasingly applied for industrial wastewater treatment. However, current knowledge of the stress responses of helophytes to selected toxicants such as dichromate is limited. The goal of the experiments presented here was to characterize the physiological response of Juncus effusus to different concentrations of dichromate dependent upon the growth and constitution of the plants. The growth parameters, shoot length, and dry weight already were strongly affected at low dichromate concentrations of approximately 34 mu M. Concentrations of 340 mu M impaired chlorophyll fluorescence and a decrease in chlorophyll a started at concentrations higher than 170 mu M dichromate. The concentrations of chlorophyll b and carotenoids also were influenced negatively. Thus, the reduction of the pigment content started before any obvious influence on the chlorophyll fluorescence. The highest concentration of dichromate, which caused no permanent inhibition of growth and photosynthesis, was found to be 17 mu M K2Cr2O7. In principle, J. effusus is suitable for constructed wetlands to treat chromium-containing wastewater. Because the stress resistance of J. effusus is limited, the maximum concentration of dichromate in the treated wastewater should not exceed 34 mu M. The growth parameters, shoot length, and dry weight were sensitive to much lower dichromate concentrations and did react more quickly than the biochemistry-related parameters chlorophyll fluorescence and pigment concentration. Therefore, the example of Juncus effusus shows that the use of only biochemical parameters to define concentration limits for the treatment of dichromate-containing wastewater can lead to incorrect conclusions and result in disturbed long-term operation of the system.","Physiological responses of Juncus effusus (rush) to chromium and relevance for wastewater treatment in constructed wetlands Abs: Constructed wetlands are increasingly applied for industrial wastewater treatment. However, current knowledge of the stress responses of helophytes to selected toxicants such as dichromate is limited. The goal of the experiments presented here was to characterize the physiological response of Juncus effusus to different concentrations of dichromate dependent upon the growth and constitution of the plants. The growth parameters, shoot length, and dry weight already were strongly affected at low dichromate concentrations of approximately 34 mu M. Concentrations of 340 mu M impaired chlorophyll fluorescence and a decrease in chlorophyll a started at concentrations higher than 170 mu M dichromate. The concentrations of chlorophyll b and carotenoids also were influenced negatively. Thus, the reduction of the pigment content started before any obvious influence on the chlorophyll fluorescence. The highest concentration of dichromate, which caused no permanent inhibition of growth and photosynthesis, was found to be 17 mu M K2Cr2O7. In principle, J. effusus is suitable for constructed wetlands to treat chromium-containing wastewater. Because the stress resistance of J. effusus is limited, the maximum concentration of dichromate in the treated wastewater should not exceed 34 mu M. The growth parameters, shoot length, and dry weight were sensitive to much lower dichromate concentrations and did react more quickly than the biochemistry-related parameters chlorophyll fluorescence and pigment concentration. Therefore, the example of Juncus effusus shows that the use of only biochemical parameters to define concentration limits for the treatment of dichromate-containing wastewater can lead to incorrect conclusions and result in disturbed long-term operation of the system."
476238,Grlickova-Duzevik et al. 2006,"XRCC1 protects cells from chromate-induced chromosome damage, but does not affect cytotoxicity","Hexavalent chromium Cr(VI) is a well known human carcinogen. This genotoxic metal induces DNA strand breaks and chromosome damage. However, the relationship between these lesions is uncertain. Our study focused on examining the role of XRCC1 in sodium chromate-induced cytotoxicity and chromosomal aberrations in Chinese Hamster Ovary (CHO) cells. Three different cell lines were used: AA8 (parental), EM9 (XRCC1 mutant) and H9T3 (EM9 complemented with human XRCC1 gene). Results show that concentration-dependent decreases in relative survival are similar in all three cell lines, indicating that XRCC1 is not crucial for protecting cells from sodium chromate-induced cytotoxicity. Similarly the frequency of damaged metaphase cells was not affected by XRCC1 deficiency. However, the total number of Cr(VI)-induced chromosome aberrations was exacerbated by XRCC1 deficiency and the spectrum of chromosome damage changed dramatically. Specifically, chromatid and isochromatid lesions were the most prominent aberrations induced in the cell lines and XRCC1 was essential to reduce the formation of chromatid lesions. In addition, XRCC1 deficiency caused a dramatic increase in the number of chromatid exchanges indicating that it is involved in protection from Cr(VI)-induced chromosome instability. (c) 2006 Elsevier B.V. All rights reserved.","XRCC1 protects cells from chromate-induced chromosome damage, but does not affect cytotoxicity Abs: Hexavalent chromium Cr(VI) is a well known human carcinogen. This genotoxic metal induces DNA strand breaks and chromosome damage. However, the relationship between these lesions is uncertain. Our study focused on examining the role of XRCC1 in sodium chromate-induced cytotoxicity and chromosomal aberrations in Chinese Hamster Ovary (CHO) cells. Three different cell lines were used: AA8 (parental), EM9 (XRCC1 mutant) and H9T3 (EM9 complemented with human XRCC1 gene). Results show that concentration-dependent decreases in relative survival are similar in all three cell lines, indicating that XRCC1 is not crucial for protecting cells from sodium chromate-induced cytotoxicity. Similarly the frequency of damaged metaphase cells was not affected by XRCC1 deficiency. However, the total number of Cr(VI)-induced chromosome aberrations was exacerbated by XRCC1 deficiency and the spectrum of chromosome damage changed dramatically. Specifically, chromatid and isochromatid lesions were the most prominent aberrations induced in the cell lines and XRCC1 was essential to reduce the formation of chromatid lesions. In addition, XRCC1 deficiency caused a dramatic increase in the number of chromatid exchanges indicating that it is involved in protection from Cr(VI)-induced chromosome instability. (c) 2006 Elsevier B.V. All rights reserved."
476236,Grlickova-Duzevik et al. 2006,XRCC1 protects against particulate chromate-induced chromosome damage and cytotoxicity in Chinese hamster ovary cells,"Water-insoluble hexavalent chromium compounds are well-established human lung carcinogens. Lead chromate, a model insoluble Cr(VI) compound, induces DNA damage, chromosome aberrations, and dose-dependent cell death in human and Chinese hamster ovary (CHO) cells. The relationship between lead chromate-induced DNA damage and chromosome aberrations is unknown. Our study focus was on examining the role of XRCC1 in lead chromate-induced cytotoxicity and structural chromosomal aberrations in CHO cells. Three different cell lines were used: AA8 (parental), EM9 (XRCC1 mutant), and H9T3 (EM9 complemented with human XRCC1 gene). Cytotoxicity was significantly higher in EM9 cells when compared to AA8 and H9T3 cells, indicating that XRCC1 is important for protecting cells from lead chromate particles-induced cell death. The frequency of damaged metaphase cells was not affected by XRCC1 deficiency. However, the total amount of Cr(VI)-induced chromosome damage was exacerbated by XRCC1 deficiency, and the spectrum of damage changed dramatically. Chromatid and isochromatid lesions were the most prominent aberrations induced in all cell lines. XRCC1 was essential to reduce the formation of chromatid lesions but not for isochromatid lesions. In addition, XRCC1 deficiency resulted in a dramatic increase in the number of chromatid exchanges, indicating that XRCC1 is involved in protection from lead chromate-induced chromosome instability.","XRCC1 protects against particulate chromate-induced chromosome damage and cytotoxicity in Chinese hamster ovary cells Abs: Water-insoluble hexavalent chromium compounds are well-established human lung carcinogens. Lead chromate, a model insoluble Cr(VI) compound, induces DNA damage, chromosome aberrations, and dose-dependent cell death in human and Chinese hamster ovary (CHO) cells. The relationship between lead chromate-induced DNA damage and chromosome aberrations is unknown. Our study focus was on examining the role of XRCC1 in lead chromate-induced cytotoxicity and structural chromosomal aberrations in CHO cells. Three different cell lines were used: AA8 (parental), EM9 (XRCC1 mutant), and H9T3 (EM9 complemented with human XRCC1 gene). Cytotoxicity was significantly higher in EM9 cells when compared to AA8 and H9T3 cells, indicating that XRCC1 is important for protecting cells from lead chromate particles-induced cell death. The frequency of damaged metaphase cells was not affected by XRCC1 deficiency. However, the total amount of Cr(VI)-induced chromosome damage was exacerbated by XRCC1 deficiency, and the spectrum of damage changed dramatically. Chromatid and isochromatid lesions were the most prominent aberrations induced in all cell lines. XRCC1 was essential to reduce the formation of chromatid lesions but not for isochromatid lesions. In addition, XRCC1 deficiency resulted in a dramatic increase in the number of chromatid exchanges, indicating that XRCC1 is involved in protection from lead chromate-induced chromosome instability."
472873,Gambelunghe et al. 2006,Chromium VI-induced apoptosis in a human bronchial epithelial cell line (BEAS-2B) and a lymphoblastic leukemia cell line (MOLT-4),"Hexavalent chromium compounds are well-documented human carcinogens. In vitro experiments show Cr (VI) induces cell death by apoptosis by activating p53 protein. The aim of this study was to evaluate Cr (VI)-induced apoptosis in a human bronchial epithelial cell line (BEAS-2B) and in a lymphoblastic leukemia cell line (MOLT-4). Cr (VI) caused a dose- and time-dependent increase in the apoptosis rate in both cell lines. Western blotting showed increased p53 protein expression in MOLT-4 cells, but not in BEAS-2B cells, after exposure to 0.5 and 3 mu M hexavalent chromium for 12 hours and 4 hours, respectively. Apoptotic cell death induced by Cr (VI) was not decreased by pretreatment with caspase-3, -8, and -9 inhibitors. These preliminary,S results provide evidence of Cr (VI)-induced apoptosis, which deserve further investigation in occupationally exposed workers.","Chromium VI-induced apoptosis in a human bronchial epithelial cell line (BEAS-2B) and a lymphoblastic leukemia cell line (MOLT-4) Abs: Hexavalent chromium compounds are well-documented human carcinogens. In vitro experiments show Cr (VI) induces cell death by apoptosis by activating p53 protein. The aim of this study was to evaluate Cr (VI)-induced apoptosis in a human bronchial epithelial cell line (BEAS-2B) and in a lymphoblastic leukemia cell line (MOLT-4). Cr (VI) caused a dose- and time-dependent increase in the apoptosis rate in both cell lines. Western blotting showed increased p53 protein expression in MOLT-4 cells, but not in BEAS-2B cells, after exposure to 0.5 and 3 mu M hexavalent chromium for 12 hours and 4 hours, respectively. Apoptotic cell death induced by Cr (VI) was not decreased by pretreatment with caspase-3, -8, and -9 inhibitors. These preliminary,S results provide evidence of Cr (VI)-induced apoptosis, which deserve further investigation in occupationally exposed workers."
472439,Fulladosa et al. 2006,Stress proteins induced by exposure to sublethal levels of heavy metals in sea bream (Sparus sarba) blood cells,"Blood cells freshly collected from silver sea bream (Sparus sarba) were exposed in vitro to different sublethal concentrations of cadmium(II), lead(II) or chromium(VI). HSP70 stress proteins were significantly overexpressed after exposure to metal concentration as low as 0.1 mu M. Under our experimental conditions, no overexpression of metallothioneins in blood cells was evidenced. Our results show that fish blood cells may constitute an interesting biological model for experimental and applied toxicology, especially in the case of environmental pollution. (c) 2005 Elsevier Ltd. All rights reserved.","Stress proteins induced by exposure to sublethal levels of heavy metals in sea bream (Sparus sarba) blood cells Abs: Blood cells freshly collected from silver sea bream (Sparus sarba) were exposed in vitro to different sublethal concentrations of cadmium(II), lead(II) or chromium(VI). HSP70 stress proteins were significantly overexpressed after exposure to metal concentration as low as 0.1 mu M. Under our experimental conditions, no overexpression of metallothioneins in blood cells was evidenced. Our results show that fish blood cells may constitute an interesting biological model for experimental and applied toxicology, especially in the case of environmental pollution. (c) 2005 Elsevier Ltd. All rights reserved."
471952,Frei et al. 2009,Fluctuations in Precambrian atmospheric oxygenation recorded by chromium isotopes,"Geochemical data(1-4) suggest that oxygenation of the Earth's atmosphere occurred in two broad steps. The first rise in atmospheric oxygen is thought to have occurred between similar to 2.45 and 2.2 Gyr ago(1,5), leading to a significant increase in atmospheric oxygen concentrations and concomitant oxygenation of the shallow surface ocean. The second increase in atmospheric oxygen appears to have taken place in distinct stages during the late Neoproterozoic era (similar to 800-542 Myr ago)(3,4), ultimately leading to oxygenation of the deep ocean similar to 580 Myr ago(3), but details of the evolution of atmospheric oxygenation remain uncertain. Here we use chromium (Cr) stable isotopes from banded iron formations (BIFs) to track the presence of Cr(VI) in Precambrian oceans, providing a time-resolved picture of the oxygenation history of the Earth's atmosphere-hydrosphere system. The geochemical behaviour of Cr is highly sensitive to the redox state of the surface environment because oxidative weathering processes produce the oxidized hexavalent [Cr(VI)] form. Oxidation of reduced trivalent [Cr(III)] chromium on land is accompanied by an isotopic fractionation, leading to enrichment of the mobile hexavalent form in the heavier isotope. Our fractionated Cr isotope data indicate the accumulation of Cr(VI) in ocean surface waters similar to 2.8 to 2.6 Gyr ago and a likely transient elevation in atmospheric and surface ocean oxygenation before the first great rise of oxygen 2.45-2.2 Gyr ago ( the Great Oxidation Event)(1,5). In similar to 1.88-Gyr-old BIFs we find that Cr isotopes are not fractionated, indicating a decline in atmospheric oxygen. Our findings suggest that the Great Oxidation Event did not lead to a unidirectional stepwise increase in atmospheric oxygen. In the late Neoproterozoic, we observe strong positive fractionations in Cr isotopes (delta(53) Cr up to +4.9 parts per thousand), providing independent support for increased surface oxygenation at that time, which may have stimulated rapid evolution of macroscopic multicellular life(3,4,6).","Fluctuations in Precambrian atmospheric oxygenation recorded by chromium isotopes Abs: Geochemical data(1-4) suggest that oxygenation of the Earth's atmosphere occurred in two broad steps. The first rise in atmospheric oxygen is thought to have occurred between similar to 2.45 and 2.2 Gyr ago(1,5), leading to a significant increase in atmospheric oxygen concentrations and concomitant oxygenation of the shallow surface ocean. The second increase in atmospheric oxygen appears to have taken place in distinct stages during the late Neoproterozoic era (similar to 800-542 Myr ago)(3,4), ultimately leading to oxygenation of the deep ocean similar to 580 Myr ago(3), but details of the evolution of atmospheric oxygenation remain uncertain. Here we use chromium (Cr) stable isotopes from banded iron formations (BIFs) to track the presence of Cr(VI) in Precambrian oceans, providing a time-resolved picture of the oxygenation history of the Earth's atmosphere-hydrosphere system. The geochemical behaviour of Cr is highly sensitive to the redox state of the surface environment because oxidative weathering processes produce the oxidized hexavalent [Cr(VI)] form. Oxidation of reduced trivalent [Cr(III)] chromium on land is accompanied by an isotopic fractionation, leading to enrichment of the mobile hexavalent form in the heavier isotope. Our fractionated Cr isotope data indicate the accumulation of Cr(VI) in ocean surface waters similar to 2.8 to 2.6 Gyr ago and a likely transient elevation in atmospheric and surface ocean oxygenation before the first great rise of oxygen 2.45-2.2 Gyr ago ( the Great Oxidation Event)(1,5). In similar to 1.88-Gyr-old BIFs we find that Cr isotopes are not fractionated, indicating a decline in atmospheric oxygen. Our findings suggest that the Great Oxidation Event did not lead to a unidirectional stepwise increase in atmospheric oxygen. In the late Neoproterozoic, we observe strong positive fractionations in Cr isotopes (delta(53) Cr up to +4.9 parts per thousand), providing independent support for increased surface oxygenation at that time, which may have stimulated rapid evolution of macroscopic multicellular life(3,4,6)."
471429,Fornsaglio et al. 2005,Differential impact of ionic and coordinate covalent chromium (Cr)-DNA binding on DNA replication,"The reactive species produced by the reduction of Cr(VI), particularly Cr(III), can form both ionic and coordinate covalent complexes with DNA. These Cr(III)-DNA interactions consist of Cr-DNA monoadducts, Cr-DNA ternary adducts, and Cr-DNA interstrand cross-links (Cr-ICLs), the latter of which are DNA polymerase arresting lesions (PALs). We sought to determine the impact of Cr-DNA interactions on the formation of replication blocking lesions in S. cerevisiae using a PCR-based method. We found that target sequence (TS) amplification using DNA isolated from Cr(VI)-treated yeast actually increased as a function of Cr(VI) concentration. Moreover, the enhanced TS amplification was reproduced in vitro using Cr(III)-treated DNA. In contrast, PCR amplification of TS from DNA isolated from yeast exposed to equitoxic doses of the inorganic DNA cross-linking agent cisplatin (CDDP), was decreased in a concentration-dependent manner. This paradox suggested that a specific Cr-DNA interaction, such as an ionic Cr-DNA complex, was responsible for the enhanced TS amplification, thereby masking the replication-blocking effect of certain ternary Cr-DNA adducts (i.e. interstrand cross-links). To test this possibility, we removed ionically associated Cr from the DNA using salt extraction prior to PCR analysis. This procedure obviated the increased amplification and revealed a dose-dependent decrease in TS amplification and an increase in Cr-PALs. These data from DNA analyzed ex vivo after treatment of intact cells indicate that ionic interactions of Cr with DNA result in increased DNA amplification whereas coordinate-covalent Cr-DNA complexes lead to formation of Cr-PALs. Thus, these results suggest that treatment of living cells with Cr(VI) leads to two modes of Cr-binding, which may have conflicting effects on DNA replication.","Differential impact of ionic and coordinate covalent chromium (Cr)-DNA binding on DNA replication Abs: The reactive species produced by the reduction of Cr(VI), particularly Cr(III), can form both ionic and coordinate covalent complexes with DNA. These Cr(III)-DNA interactions consist of Cr-DNA monoadducts, Cr-DNA ternary adducts, and Cr-DNA interstrand cross-links (Cr-ICLs), the latter of which are DNA polymerase arresting lesions (PALs). We sought to determine the impact of Cr-DNA interactions on the formation of replication blocking lesions in S. cerevisiae using a PCR-based method. We found that target sequence (TS) amplification using DNA isolated from Cr(VI)-treated yeast actually increased as a function of Cr(VI) concentration. Moreover, the enhanced TS amplification was reproduced in vitro using Cr(III)-treated DNA. In contrast, PCR amplification of TS from DNA isolated from yeast exposed to equitoxic doses of the inorganic DNA cross-linking agent cisplatin (CDDP), was decreased in a concentration-dependent manner. This paradox suggested that a specific Cr-DNA interaction, such as an ionic Cr-DNA complex, was responsible for the enhanced TS amplification, thereby masking the replication-blocking effect of certain ternary Cr-DNA adducts (i.e. interstrand cross-links). To test this possibility, we removed ionically associated Cr from the DNA using salt extraction prior to PCR analysis. This procedure obviated the increased amplification and revealed a dose-dependent decrease in TS amplification and an increase in Cr-PALs. These data from DNA analyzed ex vivo after treatment of intact cells indicate that ionic interactions of Cr with DNA result in increased DNA amplification whereas coordinate-covalent Cr-DNA complexes lead to formation of Cr-PALs. Thus, these results suggest that treatment of living cells with Cr(VI) leads to two modes of Cr-binding, which may have conflicting effects on DNA replication."
465833,Di Gioacchino et al. 2008,Autophagy in hematopoietic stem/progenitor cells exposed to heavy metals - Biological implications and toxicological relevance,"The inherent toxicity of many metal compounds, together with their widespread environmental distribution, raises concerns of potential health hazards. Little is known about the impact of these important environmental toxicants on adult stem/progenitor cells, necessary for tissue homeostasis and repair. We recently reported that autophagy is implicated in the response of hernatopoietic stem/progenitor cells to toxic concentrations of hexavalent chromium (Cr[VI]) and cadmium (U), two well-known carcinogenic heavy metal cations. Autophagy may lead to cell death if carried out too extensively, but also acts as a survival pathway in cells under stress. In stem/progenitor cells, an autophagic phenotype could mitigate metal-induced toxicity, contributing to the conservation of tissue renewal capability. Given the key role of toxic damage to adult stem/progenitor cells in cancer, it is necessary to investigate whether autophagic responses modulate the carcinogenic potential of exposure to heavy metals during stem/progenitor cell differentiation.","Autophagy in hematopoietic stem/progenitor cells exposed to heavy metals - Biological implications and toxicological relevance Abs: The inherent toxicity of many metal compounds, together with their widespread environmental distribution, raises concerns of potential health hazards. Little is known about the impact of these important environmental toxicants on adult stem/progenitor cells, necessary for tissue homeostasis and repair. We recently reported that autophagy is implicated in the response of hernatopoietic stem/progenitor cells to toxic concentrations of hexavalent chromium (Cr[VI]) and cadmium (U), two well-known carcinogenic heavy metal cations. Autophagy may lead to cell death if carried out too extensively, but also acts as a survival pathway in cells under stress. In stem/progenitor cells, an autophagic phenotype could mitigate metal-induced toxicity, contributing to the conservation of tissue renewal capability. Given the key role of toxic damage to adult stem/progenitor cells in cancer, it is necessary to investigate whether autophagic responses modulate the carcinogenic potential of exposure to heavy metals during stem/progenitor cell differentiation."
464270,Dazy et al. 2008,Antioxidant enzyme activities as affected by trivalent and hexavalent chromium species in Fontinalis antipyretica Hedw,"The detoxification mechanisms of the aquatic moss, Fontinalis antipyretica Hedw., exposed to Cr was analyzed. In addition, the influence of Cr salts (as Cr nitrate, chloride and potassium bichromate) on these mechanisms has also been studied. The activity of antioxidant enzymes superoxide dismutase (SOD, EC 1.15.1.1.), catalase (EC 1.11.1.6.), ascorbate peroxidase (APX, EC 1.11.1.11), guaiacol peroxidase (GPX, EC 1.11.1.7.) and glutathione reductase (GR, EC 1.6.4.2.) increased in plants treated with Cr concentrations ranging from 6.25 X 10(-5) to 6.25 mM when given as Cr(NO3)(3). Antioxidant enzymes responded to the other two salts CrCl3 and K2Cr2O7 only with Cr concentrations higher than 6.25 x 10(-2) mM. Glutathione level and GSSG/GSH ratio also responded to Cr exposure but no dose-effect relationship could be observed. Moreover, two unknown thiol compounds were observed in mosses exposed to the highest Cr concentrations. Effects on chlorophyll contents and chlorophyll a/b ratios were also shown even at low Cr concentrations. Our results indicated that environmentally realistic concentrations of Cr could lead to impairment of the cellular activity towards F. antipyretica and that Cr(III), when present as a nitrate salt, was as harmful as Cr(VI). (C) 2008 Elsevier Ltd. All rights reserved.","Antioxidant enzyme activities as affected by trivalent and hexavalent chromium species in Fontinalis antipyretica Hedw Abs: The detoxification mechanisms of the aquatic moss, Fontinalis antipyretica Hedw., exposed to Cr was analyzed. In addition, the influence of Cr salts (as Cr nitrate, chloride and potassium bichromate) on these mechanisms has also been studied. The activity of antioxidant enzymes superoxide dismutase (SOD, EC 1.15.1.1.), catalase (EC 1.11.1.6.), ascorbate peroxidase (APX, EC 1.11.1.11), guaiacol peroxidase (GPX, EC 1.11.1.7.) and glutathione reductase (GR, EC 1.6.4.2.) increased in plants treated with Cr concentrations ranging from 6.25 X 10(-5) to 6.25 mM when given as Cr(NO3)(3). Antioxidant enzymes responded to the other two salts CrCl3 and K2Cr2O7 only with Cr concentrations higher than 6.25 x 10(-2) mM. Glutathione level and GSSG/GSH ratio also responded to Cr exposure but no dose-effect relationship could be observed. Moreover, two unknown thiol compounds were observed in mosses exposed to the highest Cr concentrations. Effects on chlorophyll contents and chlorophyll a/b ratios were also shown even at low Cr concentrations. Our results indicated that environmentally realistic concentrations of Cr could lead to impairment of the cellular activity towards F. antipyretica and that Cr(III), when present as a nitrate salt, was as harmful as Cr(VI). (C) 2008 Elsevier Ltd. All rights reserved."
462263,Coors et al. 2009,"Land use, genetic diversity and toxicant tolerance in natural populations of Daphnia magna","Provided that gene flow is not too high, selection by local environmental conditions in heterogeneous landscapes can lead to genetic adaptation of natural populations to their local habitat. Pollution with anthropogenic toxicants may create pronounced environmental gradients that impose strong local selection pressures. Toxic contaminants may also directly impact genetic structure in natural populations by exhibiting genotoxicity or by causing population declines resulting in genetic bottlenecks. Using populations of Daphnia magna established from the dormant egg banks of ponds located in a landscape dominated by anthropogenic impact, we aimed at detecting evidence for local adaptation to environmental contamination. We explored the relationship between land use around the 10 investigated ponds, population genetic diversity as measured by neutral genetic markers (polymorphic allozymes) and the tolerance of the populations originating from these ponds to acute lethal effects of two model toxicants, the pesticide carbaryl and the metal potassium dichromate. Genetic diversity of the populations as observed by neutral markers tended to be negatively impacted by agricultural land use intensity (Spearman rank correlation, R = -0.614, P = 0.059), indicating that genetic bottlenecks may have resulted from anthropogenic impact. We experimentally observed differences in susceptibility to both carbaryl and potassium dichromate among the studied pond populations of D. magna (analysis of deviance, P < 0.001). Because the experimental design excluded the possibility of physiological adaptation of the test animals to the toxicants, we conclude that the differences in susceptibility must have a genetic basis. Moreover, carbaryl tolerance levels of the populations tended to increase with increasing agricultural land use intensity as described by ranked percentage of land coverage with cereal and corn crop in the proximity of the ponds (Spearman rank correlation, R = 0.602, P = 0.066). Together, these two findings provide evidence for local adaptation of D. magna populations to pesticide contamination. Overall, the results demonstrate the potential selection pressure imposed by anthropogenic pollution and provide evidence that genetic erosion in natural Daphnia populations is related to anthropogenic impact. (C) 2009 Elsevier B.V. All rights reserved.","Land use, genetic diversity and toxicant tolerance in natural populations of Daphnia magna Abs: Provided that gene flow is not too high, selection by local environmental conditions in heterogeneous landscapes can lead to genetic adaptation of natural populations to their local habitat. Pollution with anthropogenic toxicants may create pronounced environmental gradients that impose strong local selection pressures. Toxic contaminants may also directly impact genetic structure in natural populations by exhibiting genotoxicity or by causing population declines resulting in genetic bottlenecks. Using populations of Daphnia magna established from the dormant egg banks of ponds located in a landscape dominated by anthropogenic impact, we aimed at detecting evidence for local adaptation to environmental contamination. We explored the relationship between land use around the 10 investigated ponds, population genetic diversity as measured by neutral genetic markers (polymorphic allozymes) and the tolerance of the populations originating from these ponds to acute lethal effects of two model toxicants, the pesticide carbaryl and the metal potassium dichromate. Genetic diversity of the populations as observed by neutral markers tended to be negatively impacted by agricultural land use intensity (Spearman rank correlation, R = -0.614, P = 0.059), indicating that genetic bottlenecks may have resulted from anthropogenic impact. We experimentally observed differences in susceptibility to both carbaryl and potassium dichromate among the studied pond populations of D. magna (analysis of deviance, P < 0.001). Because the experimental design excluded the possibility of physiological adaptation of the test animals to the toxicants, we conclude that the differences in susceptibility must have a genetic basis. Moreover, carbaryl tolerance levels of the populations tended to increase with increasing agricultural land use intensity as described by ranked percentage of land coverage with cereal and corn crop in the proximity of the ponds (Spearman rank correlation, R = 0.602, P = 0.066). Together, these two findings provide evidence for local adaptation of D. magna populations to pesticide contamination. Overall, the results demonstrate the potential selection pressure imposed by anthropogenic pollution and provide evidence that genetic erosion in natural Daphnia populations is related to anthropogenic impact. (C) 2009 Elsevier B.V. All rights reserved."
460471,Chidambaram et al. 2009,CHROMIUM INDUCED CYTOTOXICITY IN BLACKGRAM (VIGNA MUNGO L.),"Chromium is known to be highly toxic to biological systems. This study was designed to determine the mutagenic effects of different concentrations ( 0, 10, 25, 50, 100 and 200 mg/L) of hexavalent chromium on root tip cells of blackgram (Vigna mungo L. Hepper). The blackgram seeds were equi-spacially arranged in sterilized petriplates lined with filter paper and they were treated with different concentrations of chromium solution. In germination studies, the morphological growth parameters such as germination percentage, root length, shoot length fresh weight and dry weight of blackgram seedlings were decreased with increasing dose of chromium concentrations. No germination of blackgram seeds was recorded at 300mg/l chromium concentration. Chromosome aberration assay was used to determine the mitotic indices and rate of chromosome aberration in blackgram root tip cells due to chromium treatment. The results showed that the mitotic indices were complicated due to different concentrations of chromium. However, the increase in chromium concentration has led to a gradual increase in the percentage of chromosomal aberration and mitotic index. The chromosome length, absolute chromosome length and average chromosome lengths were gradually found to decrease. There was no considerable change in 2n number of chromosome with the increase in chromium concentrations. It is concluded that the hexavalent chromium has significant mutagenic effect on the root tip cells of blackgram.","CHROMIUM INDUCED CYTOTOXICITY IN BLACKGRAM (VIGNA MUNGO L.) Abs: Chromium is known to be highly toxic to biological systems. This study was designed to determine the mutagenic effects of different concentrations ( 0, 10, 25, 50, 100 and 200 mg/L) of hexavalent chromium on root tip cells of blackgram (Vigna mungo L. Hepper). The blackgram seeds were equi-spacially arranged in sterilized petriplates lined with filter paper and they were treated with different concentrations of chromium solution. In germination studies, the morphological growth parameters such as germination percentage, root length, shoot length fresh weight and dry weight of blackgram seedlings were decreased with increasing dose of chromium concentrations. No germination of blackgram seeds was recorded at 300mg/l chromium concentration. Chromosome aberration assay was used to determine the mitotic indices and rate of chromosome aberration in blackgram root tip cells due to chromium treatment. The results showed that the mitotic indices were complicated due to different concentrations of chromium. However, the increase in chromium concentration has led to a gradual increase in the percentage of chromosomal aberration and mitotic index. The chromosome length, absolute chromosome length and average chromosome lengths were gradually found to decrease. There was no considerable change in 2n number of chromosome with the increase in chromium concentrations. It is concluded that the hexavalent chromium has significant mutagenic effect on the root tip cells of blackgram."
459995,Chen et al. 2009,Cytotoxicity and genotoxicity of hexavalent chromium in human and North Atlantic right whale (Eubalaena glacialis) lung cells,"Humans and cetaceans are exposed to a wide range of contaminants. In this study, we compared the cytotoxic and genotoxic effects of a metal pollutant, hexavalent chromium [Cr(VI)], which has been shown to cause damage in lung cells from both humans and North Atlantic right whales. Our results show that Cr induces increased cell death and chromosome damage in lung cells from both species with increasing intracellular Cr ion levels. Soluble Cr(VI) induced less of a cytotoxic and genotoxic effect based on administered dose in right whale (Eubalaena glacialis) cells than in human (Homo sapiens) cells. Whereas, particulate Cr(VI) induced a similar cytotoxic effect but less of a genotoxic effect based on administered dose in right whale cells than in human cells. Differences in chromium ion uptake explained soluble chromate-induced cell death but not all of the soluble chromate-induced chromosome damage. Uptake differences of lead ions could explain the differences in particulate chromate-induced toxicity. The data show that both forms of Cr(VI) are less genotoxic to right whale than human lung cells, and that soluble Cr(VI) induces a similar cytotoxic effect in both right whale and human cells, while particulate Cr(VI) is more cytotoxic to right whale lung cells. (C) 2009 Elsevier Inc. All rights reserved.","Cytotoxicity and genotoxicity of hexavalent chromium in human and North Atlantic right whale (Eubalaena glacialis) lung cells Abs: Humans and cetaceans are exposed to a wide range of contaminants. In this study, we compared the cytotoxic and genotoxic effects of a metal pollutant, hexavalent chromium [Cr(VI)], which has been shown to cause damage in lung cells from both humans and North Atlantic right whales. Our results show that Cr induces increased cell death and chromosome damage in lung cells from both species with increasing intracellular Cr ion levels. Soluble Cr(VI) induced less of a cytotoxic and genotoxic effect based on administered dose in right whale (Eubalaena glacialis) cells than in human (Homo sapiens) cells. Whereas, particulate Cr(VI) induced a similar cytotoxic effect but less of a genotoxic effect based on administered dose in right whale cells than in human cells. Differences in chromium ion uptake explained soluble chromate-induced cell death but not all of the soluble chromate-induced chromosome damage. Uptake differences of lead ions could explain the differences in particulate chromate-induced toxicity. The data show that both forms of Cr(VI) are less genotoxic to right whale than human lung cells, and that soluble Cr(VI) induces a similar cytotoxic effect in both right whale and human cells, while particulate Cr(VI) is more cytotoxic to right whale lung cells. (C) 2009 Elsevier Inc. All rights reserved."
459217,Chang et al. 2006,Biomonitoring of chromium for residents of areas with a high density of electroplating factories,"The high density of electroplating factories in the geographic middle of Taiwan has prompted concern over the potential for exposure to harmful metals. The present study aimed to determine the levels of chromium in whole blood (B-Cr) of residents living in the high vs. low factory-density areas,and to examine the relations to gender and age. A total of 660 residents who had not moved within the 5 years preceding the study were sampled according to the stratified random sampling approach, at ages 35 - 44, 45 - 54, and 55 - 64 years, for both genders. Chromium determinations (n = 641) were made using a graphite furnace atomic absorption spectrometer. The geometric mean ( 95% C. I.) of B-Cr was 0.357 (0.34-0.38) mu g/l. The International Federation of Clinical Chemistry(IFCC) nonparametric 0.95 reference limits of B-Cr was estimated to be < 0.905 mu g/l. B-Cr levels decreased with increasing age. Subjects in the areas with a high density(0.38 mu g/l, 95% C.I.:0.36-0.40) of electroplating factories had significantly higher B-Cr levels, compared to residents of the low-density(0.27, 0.25-0.30) areas and to the general population from western countries. The health significance of the elevated B-Cr remains to be determined.","Biomonitoring of chromium for residents of areas with a high density of electroplating factories Abs: The high density of electroplating factories in the geographic middle of Taiwan has prompted concern over the potential for exposure to harmful metals. The present study aimed to determine the levels of chromium in whole blood (B-Cr) of residents living in the high vs. low factory-density areas,and to examine the relations to gender and age. A total of 660 residents who had not moved within the 5 years preceding the study were sampled according to the stratified random sampling approach, at ages 35 - 44, 45 - 54, and 55 - 64 years, for both genders. Chromium determinations (n = 641) were made using a graphite furnace atomic absorption spectrometer. The geometric mean ( 95% C. I.) of B-Cr was 0.357 (0.34-0.38) mu g/l. The International Federation of Clinical Chemistry(IFCC) nonparametric 0.95 reference limits of B-Cr was estimated to be < 0.905 mu g/l. B-Cr levels decreased with increasing age. Subjects in the areas with a high density(0.38 mu g/l, 95% C.I.:0.36-0.40) of electroplating factories had significantly higher B-Cr levels, compared to residents of the low-density(0.27, 0.25-0.30) areas and to the general population from western countries. The health significance of the elevated B-Cr remains to be determined."
457684,Camyre et al. 2007,Ku80 deficiency does not affect particulate chromate-induced chromosome damage and cytotoxicity in Chinese hamster ovary cells,"Particulate hexavalent chromium ((Cr(VI)) compounds are human lung carcinogens. These compounds induce DNA damage, chromosome aberrations, and concentration-de pendent cell death in human and Chinese hamster ovary (CHO) cells. The relationship between Cr(VI)-induced DNA damage and chromosome aberrations is poorly understood. Accordingly, this study focused on examining the role of Ku80, a gene involved in nonhomologous end-joining repair, in particulate chromate-induced cytotoxicity and chromosome damage in CHO cells. Three different cell lines were used: CHO-K1 (parental), xrs-6 (Ku80 deficient), and 2E (xrs-6 complemented with Ku80 gene). Levels of cell death were higher in xrs-6 cells when compared to wild type, suggesting that Ku80 was important for protecting cells from lead chromate. However, Ku80 played no role in protecting cells from particulate Cr(Vl)-induced chromosome instability (CIN) as gene complementation with Ku80 (2E cells) studies and uptake experiments showed similar frequency and amounts of chromosome damage between the cell lines and that any observed difference based on administered concentration was actually due to differences in Cr(VI) uptake. The spectrum of chromosome damage was also unaffected by Ku80 deficiency. These data indicate that Ku80 protects cells from cytotoxicity but is not involved in protecting cells from particulate chromate-induced CIN.","Ku80 deficiency does not affect particulate chromate-induced chromosome damage and cytotoxicity in Chinese hamster ovary cells Abs: Particulate hexavalent chromium ((Cr(VI)) compounds are human lung carcinogens. These compounds induce DNA damage, chromosome aberrations, and concentration-de pendent cell death in human and Chinese hamster ovary (CHO) cells. The relationship between Cr(VI)-induced DNA damage and chromosome aberrations is poorly understood. Accordingly, this study focused on examining the role of Ku80, a gene involved in nonhomologous end-joining repair, in particulate chromate-induced cytotoxicity and chromosome damage in CHO cells. Three different cell lines were used: CHO-K1 (parental), xrs-6 (Ku80 deficient), and 2E (xrs-6 complemented with Ku80 gene). Levels of cell death were higher in xrs-6 cells when compared to wild type, suggesting that Ku80 was important for protecting cells from lead chromate. However, Ku80 played no role in protecting cells from particulate Cr(Vl)-induced chromosome instability (CIN) as gene complementation with Ku80 (2E cells) studies and uptake experiments showed similar frequency and amounts of chromosome damage between the cell lines and that any observed difference based on administered concentration was actually due to differences in Cr(VI) uptake. The spectrum of chromosome damage was also unaffected by Ku80 deficiency. These data indicate that Ku80 protects cells from cytotoxicity but is not involved in protecting cells from particulate chromate-induced CIN."
456863,Burgess et al. 2007,Marine sediment toxicity identification evaluation methods for the anionic metals arsenic and chromium,"Marine sediments accumulate a variety of contaminants and, in some cases, demonstrate toxicity because of this contamination. Toxicity identification evaluation (TIE) methods provide tools for identifying the toxic chemicals causing sediment toxicity. Currently, whole-sediment TIE methods are not available for anionic metals like arsenic and chromium. In the present paper, we describe two new anion-exchange resins used in the development of whole-sediruent TIE methods for arsenic and chromium. Resins were shown to reduce whole-sedinient toxicity and overlying water concentrations of the anionic metals. Sediment toxicity, expressed as the median lethal concentration, was reduced by a factor of two to a factor of nearly six between amended sediment treatments containing resin and those without resin. Aqueous concentrations of arsenic and chromium in the toxicity exposures decreased to less than the detection limits or to concentrations much lower than those measured in treatments without resin. Interference studies indicated that the anion-exchange resins had no significant effect on concentrations of the representative pesticide endosulfan and minimal effects on concentrations of ammonia. However, the anion-exchange resins did significantly reduce the concentrations of a selection of cationic metals (Cd, Cu, Ni, Pb, and Zn). These data demonstrate the utility of anion-exchange resins for determining the contribution of arsenic and chromium to whole-sediment toxicity. The present results also indicate the importance of using TIE methods in a formal TIE structure to ensure that results are not misinterpreted. These methods should be useful in the performance of marine whole-sediment TIEs.","Marine sediment toxicity identification evaluation methods for the anionic metals arsenic and chromium Abs: Marine sediments accumulate a variety of contaminants and, in some cases, demonstrate toxicity because of this contamination. Toxicity identification evaluation (TIE) methods provide tools for identifying the toxic chemicals causing sediment toxicity. Currently, whole-sediment TIE methods are not available for anionic metals like arsenic and chromium. In the present paper, we describe two new anion-exchange resins used in the development of whole-sediruent TIE methods for arsenic and chromium. Resins were shown to reduce whole-sedinient toxicity and overlying water concentrations of the anionic metals. Sediment toxicity, expressed as the median lethal concentration, was reduced by a factor of two to a factor of nearly six between amended sediment treatments containing resin and those without resin. Aqueous concentrations of arsenic and chromium in the toxicity exposures decreased to less than the detection limits or to concentrations much lower than those measured in treatments without resin. Interference studies indicated that the anion-exchange resins had no significant effect on concentrations of the representative pesticide endosulfan and minimal effects on concentrations of ammonia. However, the anion-exchange resins did significantly reduce the concentrations of a selection of cationic metals (Cd, Cu, Ni, Pb, and Zn). These data demonstrate the utility of anion-exchange resins for determining the contribution of arsenic and chromium to whole-sediment toxicity. The present results also indicate the importance of using TIE methods in a formal TIE structure to ensure that results are not misinterpreted. These methods should be useful in the performance of marine whole-sediment TIEs."
456163,Brooks et al. 2008,Excision repair is required for genotoxin-induced mutagenesis in mammalian cells,"Certain hexavalent chromium [Cr(VI)] compounds are human lung carcinogens. Although much is known about Cr-induced DNA damage, very little is known about mechanisms of Cr(VI) mutagenesis and the role that DNA repair plays in this process. Our goal was to investigate the role of excision repair (ER) pathways in Cr(VI)-mediated mutagenesis in mammalian cells. Repair-proficient Chinese hamster ovary cells (AA8), nucleotide excision repair (NER)-deficient (UV-5) and base excision repair (BER)-inhibited cells were treated with Cr(VI) and monitored for forward mutation frequency at the hypoxanthine-guanine phosphoribosyltransferase (HPRT) locus. BER was inhibited using methoxyamine hydrochloride (Mx), which binds to apurinic/apyrimidinic sites generated during BER. Notably, we found that both NER-deficient (UV-5 and UV-41) and BER-inhibited (AA8 + Mx) cells displayed attenuated Cr(VI) mutagenesis. To determine whether this was unique to Cr(VI), we included the alkylating agent, methylmethane sulfonate (MMS) and ultraviolet (UV) radiation (260 nm) in our studies. Similar to Cr(VI), UV-5 cells exhibited a marked attenuation of MMS mutagenesis, but were hypermutagenic following UV exposure. Moreover, UV-5 cells expressing human xeroderma pigmentosum complementation group D displayed similar sensitivity to Cr(VI) and MMS-induced mutagenesis as AA8 controls, indicating that the genetic loss of NER was responsible for attenuated mutagenesis. Interestingly, Cr(VI)-induced clastogenesis was also attenuated in NER-deficient and BER-inhibited cells. Taken together, our results suggest that NER and BER are required for Cr(VI) and MMS-induced genomic instability. We postulate that, in the absence of ER, DNA damage is channeled into an error-free system of DNA repair or damage tolerance.","Excision repair is required for genotoxin-induced mutagenesis in mammalian cells Abs: Certain hexavalent chromium [Cr(VI)] compounds are human lung carcinogens. Although much is known about Cr-induced DNA damage, very little is known about mechanisms of Cr(VI) mutagenesis and the role that DNA repair plays in this process. Our goal was to investigate the role of excision repair (ER) pathways in Cr(VI)-mediated mutagenesis in mammalian cells. Repair-proficient Chinese hamster ovary cells (AA8), nucleotide excision repair (NER)-deficient (UV-5) and base excision repair (BER)-inhibited cells were treated with Cr(VI) and monitored for forward mutation frequency at the hypoxanthine-guanine phosphoribosyltransferase (HPRT) locus. BER was inhibited using methoxyamine hydrochloride (Mx), which binds to apurinic/apyrimidinic sites generated during BER. Notably, we found that both NER-deficient (UV-5 and UV-41) and BER-inhibited (AA8 + Mx) cells displayed attenuated Cr(VI) mutagenesis. To determine whether this was unique to Cr(VI), we included the alkylating agent, methylmethane sulfonate (MMS) and ultraviolet (UV) radiation (260 nm) in our studies. Similar to Cr(VI), UV-5 cells exhibited a marked attenuation of MMS mutagenesis, but were hypermutagenic following UV exposure. Moreover, UV-5 cells expressing human xeroderma pigmentosum complementation group D displayed similar sensitivity to Cr(VI) and MMS-induced mutagenesis as AA8 controls, indicating that the genetic loss of NER was responsible for attenuated mutagenesis. Interestingly, Cr(VI)-induced clastogenesis was also attenuated in NER-deficient and BER-inhibited cells. Taken together, our results suggest that NER and BER are required for Cr(VI) and MMS-induced genomic instability. We postulate that, in the absence of ER, DNA damage is channeled into an error-free system of DNA repair or damage tolerance."
455373,Boverhof et al. 2008,"Interlaboratory validation of 1% pluronic L92 surfactant as a suitable, aqueous vehicle for testing pesticide formulations using the murine local lymph node assay","The mouse local lymph node assay (LLNA) has become the preferred test for evaluating the dermal sensitization potential of chemicals and requirements are now emerging for its use in the evaluation of their formulated products, especially in the European Union. However, despite its widespread use and extensive validation, the use of this assay for directly testing mixtures and formulated products has been questioned, which could lead to repeat testing using multiple animal models. As pesticide formulations are typically a specific complex blend of chemicals for use as aqueous-based dilutions, traditional vehicles prescribed for the LLNA may change the properties of these formulations leading to inaccurate test results and hazard identification. The objective of this study was to evaluate the effectiveness of an aqueous solution of Pluronic L92 block copolymer surfactant (L92) as a vehicle in the mouse LLNA across five laboratories. Three chemicals with known sensitization potential and four pesticide formulations for which the sensitization potential in guinea pigs and/or humans had previously been assessed were used. Identical LLNA protocols and test materials were used in the evaluation. Assessment of the positive control chemicals, hexylcinnamaldehyde, formaldehyde, and potassium dichromate revealed positive results when using 1% aqueous L92 as the vehicle. Furthermore, results for these chemicals were reproducible among the five laboratories and demonstrated consistent relative potency determinations. The four pesticide formulations diluted in 1% aqueous L92 also demonstrated reproducible results in the LLNA among the five laboratories. Results for these test materials were also consistent with those generated previously using guinea pigs or from human experience. These data support testing aqueous compatible chemicals or pesticide formulations using the mouse LLNA, and provide additional support for the use of 1% aqueous L92 as a suitable, aqueous-based vehicle.","Interlaboratory validation of 1% pluronic L92 surfactant as a suitable, aqueous vehicle for testing pesticide formulations using the murine local lymph node assay Abs: The mouse local lymph node assay (LLNA) has become the preferred test for evaluating the dermal sensitization potential of chemicals and requirements are now emerging for its use in the evaluation of their formulated products, especially in the European Union. However, despite its widespread use and extensive validation, the use of this assay for directly testing mixtures and formulated products has been questioned, which could lead to repeat testing using multiple animal models. As pesticide formulations are typically a specific complex blend of chemicals for use as aqueous-based dilutions, traditional vehicles prescribed for the LLNA may change the properties of these formulations leading to inaccurate test results and hazard identification. The objective of this study was to evaluate the effectiveness of an aqueous solution of Pluronic L92 block copolymer surfactant (L92) as a vehicle in the mouse LLNA across five laboratories. Three chemicals with known sensitization potential and four pesticide formulations for which the sensitization potential in guinea pigs and/or humans had previously been assessed were used. Identical LLNA protocols and test materials were used in the evaluation. Assessment of the positive control chemicals, hexylcinnamaldehyde, formaldehyde, and potassium dichromate revealed positive results when using 1% aqueous L92 as the vehicle. Furthermore, results for these chemicals were reproducible among the five laboratories and demonstrated consistent relative potency determinations. The four pesticide formulations diluted in 1% aqueous L92 also demonstrated reproducible results in the LLNA among the five laboratories. Results for these test materials were also consistent with those generated previously using guinea pigs or from human experience. These data support testing aqueous compatible chemicals or pesticide formulations using the mouse LLNA, and provide additional support for the use of 1% aqueous L92 as a suitable, aqueous-based vehicle."
452219,Becerra-Torres et al. 2009,The flavonoid quercetin protects and prevents against potassium dichromate-induced systemic peroxidation of lipids and diminution in renal clearance of para-aminohippuric acid and inulin in the rat,"It is well known that exposure to chromium (Cr) can lead to nephrotoxicity. Quercetin is a flavonoid of interest because of its proposed health-promoting effects. The aim of this work was to elucidate the role of quercetin against the nephrotoxicity caused by Cr in rats. Quercetin may have positive effects in combating, or helping to prevent, nephrotoxicity. It was observed that a single dose of potassium dichromate resulted in both an increase of systemic peroxidation of lipids and a decrease of the renal clearance of para-aminohippuric acid and inulin. Our results show that treatment with quercetin protected and prevented against these damaging effects.","The flavonoid quercetin protects and prevents against potassium dichromate-induced systemic peroxidation of lipids and diminution in renal clearance of para-aminohippuric acid and inulin in the rat Abs: It is well known that exposure to chromium (Cr) can lead to nephrotoxicity. Quercetin is a flavonoid of interest because of its proposed health-promoting effects. The aim of this work was to elucidate the role of quercetin against the nephrotoxicity caused by Cr in rats. Quercetin may have positive effects in combating, or helping to prevent, nephrotoxicity. It was observed that a single dose of potassium dichromate resulted in both an increase of systemic peroxidation of lipids and a decrease of the renal clearance of para-aminohippuric acid and inulin. Our results show that treatment with quercetin protected and prevented against these damaging effects."
450514,Bae et al. 2009,Bypass of hexavalent chromium-induced growth arrest by a protein tyrosine phosphatase inhibitor: Enhanced survival and mutagenesis,"Although the consequences of genotoxic injury include cell cycle arrest and apoptosis, cell survival responses after genotoxic injury can produce intrinsic death-resistance and contribute to the development of a transformed phenotype. Protein tyrosine phosphatases (PTPs) are integral components of key Survival pathways, and are responsible for their inactivation, while PTP inhibition is often associated with enhanced cell proliferation. Our aim Was to elucidate signaling events that modulate cell Survival after genotoxin exposure. Diploid human lung fibroblasts (HLF) were treated with Cr(VI) (as Na2CrO4), the soluble oxyanionic dissolution product of certain particulate chromates, which are well-documented human respiratory carcinogens. In Vitro Soluble Cr(VI) induces a wide spectrum of DNA damage, in both the presence and absence of a broad-range PTP inhibitor, sodium orthovanadate (SOV). Notably, SOV abrogated Cr(VI)-induced clonogenic lethality. The enhanced survival of Cr(VI)-exposed cells after SOV treatment was predominantly due to a bypass of cell cycle arrest, as there was no effect of the PTP inhibitor on Cr-induced apoptosis. Moreover, the SOV effect was not due to decreased Cr uptake as evidenced by unchanged Cr-DNA adduct burden. Additionally, the bypass of Cr-induced growth arrest by SOV was accompanied by a decrease in Cr(VI)-induced expression of cell cycle inhibiting genes, and an increase in Cr(VI)-induced expression of cell cycle promoting genes. Importantly, SOV resulted in an increase in forward Mutations at the HPRT locus, supporting the hypothesis that PTP inhibition in the presence of certain types of DNA damage may lead to increased genomic instability, via bypass of cell cycle checkpoints. (c) 2008 Elsevier B.V. All rights reserved.","Bypass of hexavalent chromium-induced growth arrest by a protein tyrosine phosphatase inhibitor: Enhanced survival and mutagenesis Abs: Although the consequences of genotoxic injury include cell cycle arrest and apoptosis, cell survival responses after genotoxic injury can produce intrinsic death-resistance and contribute to the development of a transformed phenotype. Protein tyrosine phosphatases (PTPs) are integral components of key Survival pathways, and are responsible for their inactivation, while PTP inhibition is often associated with enhanced cell proliferation. Our aim Was to elucidate signaling events that modulate cell Survival after genotoxin exposure. Diploid human lung fibroblasts (HLF) were treated with Cr(VI) (as Na2CrO4), the soluble oxyanionic dissolution product of certain particulate chromates, which are well-documented human respiratory carcinogens. In Vitro Soluble Cr(VI) induces a wide spectrum of DNA damage, in both the presence and absence of a broad-range PTP inhibitor, sodium orthovanadate (SOV). Notably, SOV abrogated Cr(VI)-induced clonogenic lethality. The enhanced survival of Cr(VI)-exposed cells after SOV treatment was predominantly due to a bypass of cell cycle arrest, as there was no effect of the PTP inhibitor on Cr-induced apoptosis. Moreover, the SOV effect was not due to decreased Cr uptake as evidenced by unchanged Cr-DNA adduct burden. Additionally, the bypass of Cr-induced growth arrest by SOV was accompanied by a decrease in Cr(VI)-induced expression of cell cycle inhibiting genes, and an increase in Cr(VI)-induced expression of cell cycle promoting genes. Importantly, SOV resulted in an increase in forward Mutations at the HPRT locus, supporting the hypothesis that PTP inhibition in the presence of certain types of DNA damage may lead to increased genomic instability, via bypass of cell cycle checkpoints. (c) 2008 Elsevier B.V. All rights reserved."
449112,Apte et al. 2008,Application of DNA diffusion assay in earthworm coelomocytes,"We have applied the DNA diffusion assay proposed by Singh (2000) Exp Cell Res 256:328337, for quantitative estimation of apoptosis in earthworm coelomocytes, exposed to Chromium (VI) and cypermethrin as model toxicants in vitro. The DNA diffusion assay was originally described for mammalian cells. H2O2, Sodium ascorbate, and hyperthermia were used as positive controls in present study. Apoptosis such as DNA diffusion occurred in dose-dependent manner for Chromium (VI) and cypermethrin at very low concentration (1, 3, and 10 ppm for Chromium (VI) and 4, 8, and 16 ppm for cypermethrin). Three distinct patterns (apoptosis like DNA diffusion, necrosis, and normal) were observed in exposed and nonexposed cells. Present study is probably the first report of application of the DNA diffusion technique in earthworm coelomocytes. Findings of this study indicate that this assay has potential for use in invertebrate cells to differentiate between apoptosis and necrosis. (c) 2009 Wiley Periodicals, Inc.","Application of DNA diffusion assay in earthworm coelomocytes Abs: We have applied the DNA diffusion assay proposed by Singh (2000) Exp Cell Res 256:328337, for quantitative estimation of apoptosis in earthworm coelomocytes, exposed to Chromium (VI) and cypermethrin as model toxicants in vitro. The DNA diffusion assay was originally described for mammalian cells. H2O2, Sodium ascorbate, and hyperthermia were used as positive controls in present study. Apoptosis such as DNA diffusion occurred in dose-dependent manner for Chromium (VI) and cypermethrin at very low concentration (1, 3, and 10 ppm for Chromium (VI) and 4, 8, and 16 ppm for cypermethrin). Three distinct patterns (apoptosis like DNA diffusion, necrosis, and normal) were observed in exposed and nonexposed cells. Present study is probably the first report of application of the DNA diffusion technique in earthworm coelomocytes. Findings of this study indicate that this assay has potential for use in invertebrate cells to differentiate between apoptosis and necrosis. (c) 2009 Wiley Periodicals, Inc."
448911,Anthemidis and  Koussoroplis 2007,Determination of chromium(VI) and lead in water samples by on-line sorption preconcentration coupled with flame atomic absorption spectrometry using a PCTFE-beads packed column,"A new time-based flow injection on-line solid phase extraction method for chromium(VI) and lead determination using flame atomic absorption spectrometry was developed. The use of hydrophobic poly-chlorotrifluoroethylene (PCTFE)-beads as absorbent in on-line preconcentration system was evaluated. Effective formation of ammonium pyrrolidine dithiocarbamate complexes and subsequently retention in PCTFE packed column, was achieved in pH range 1.0-1.6 and 1.5-3.2 for Cr(VI) and Pb(II) ions, respectively. The sorbed analyte was efficiently eluted with isobutyl-methylketone for on-line FAAS determination. The proposed packing material exhibited excellent chemical and mechanical resistance, fast kinetics for adsorption of Cr(VI) and Pb(II) permitting the use of high sample flow rates at least up to 15 mL min(-1) without loss of retention efficiency. For a preconcentration time of 90 s, the sample frequency was 30 h(-1), the enhancement factor was 94 and 220, the detection limit was 0.4 and 1.2 mu g L-1, while the precision (R.S.D.) was 1.8% (at 5 mu g L-1) and 2.1% (at 30 mu g L-1) for chromium(VI) and lead, respectively. The applicability and the accuracy of the developed method were estimated by the analysis spiked water samples and certified reference material NIST-CRM 1643d (Trace elements in water) and NIST-SRM 2109 (chromium(VI) speciation in water). (c) 2006 Elsevier B.V. All rights reserved.","Determination of chromium(VI) and lead in water samples by on-line sorption preconcentration coupled with flame atomic absorption spectrometry using a PCTFE-beads packed column Abs: A new time-based flow injection on-line solid phase extraction method for chromium(VI) and lead determination using flame atomic absorption spectrometry was developed. The use of hydrophobic poly-chlorotrifluoroethylene (PCTFE)-beads as absorbent in on-line preconcentration system was evaluated. Effective formation of ammonium pyrrolidine dithiocarbamate complexes and subsequently retention in PCTFE packed column, was achieved in pH range 1.0-1.6 and 1.5-3.2 for Cr(VI) and Pb(II) ions, respectively. The sorbed analyte was efficiently eluted with isobutyl-methylketone for on-line FAAS determination. The proposed packing material exhibited excellent chemical and mechanical resistance, fast kinetics for adsorption of Cr(VI) and Pb(II) permitting the use of high sample flow rates at least up to 15 mL min(-1) without loss of retention efficiency. For a preconcentration time of 90 s, the sample frequency was 30 h(-1), the enhancement factor was 94 and 220, the detection limit was 0.4 and 1.2 mu g L-1, while the precision (R.S.D.) was 1.8% (at 5 mu g L-1) and 2.1% (at 30 mu g L-1) for chromium(VI) and lead, respectively. The applicability and the accuracy of the developed method were estimated by the analysis spiked water samples and certified reference material NIST-CRM 1643d (Trace elements in water) and NIST-SRM 2109 (chromium(VI) speciation in water). (c) 2006 Elsevier B.V. All rights reserved."
406916,Wise et al. 2007,Particulate Depleted Uranium Is Cytotoxic and Clastogenic to Human Lung Cells,"Depleted uranium (DU) is commonly used in military armor and munitions, and thus, exposure of soldiers and non-combatants is potentially frequent and widespread. DU is considered a suspected human carcinogen, affecting the bronchial cells of the lung. However, few investigations have studied DU in human bronchial cells. Accordingly, we determined the cytotoxicity and clastogenicity of both particulate (water-insoluble) and soluble DU in human bronchial fibroblasts (WTHBF-6 cells). We used uranium trioxide (UO3) and uranyl acetate (UA) as prototypical particulate and soluble DU salts, respectively. After a 24 h exposure, both UO3 and UA induced concentration-dependent cytotoxicity in WTHBF-6 cells. Specifically, 0.1, 0.5, 1, and 5 Î¼g/cm2 UO3 induced 99, 57, 32, and 1% relative survival, respectively. Similarly, 100, 200, 400, and 800 Î¼M UA induced 98, 92, 70, and 56% relative survival, respectively. When treated with chronic exposure, up to 72 h, of either UO3 or UA, there was an increased degree of cytotoxicity. We assessed the clastogenicity of these compounds and found that at concentrations of 0, 0.5, 1, and 5 Î¼g/cm2 UO3, 5, 6, 10, and 15% of metaphase cells exhibit some form of chromosome damage. UA did not induce chromosome damage above background levels. There were slight increases in chromosome damage induced when we extended the UO3 treatment time to 48 or 72 h, but no meaningful increase in chromosome damage was observed with chronic exposure to UA.","Particulate Depleted Uranium Is Cytotoxic and Clastogenic to Human Lung Cells Abs: Depleted uranium (DU) is commonly used in military armor and munitions, and thus, exposure of soldiers and non-combatants is potentially frequent and widespread. DU is considered a suspected human carcinogen, affecting the bronchial cells of the lung. However, few investigations have studied DU in human bronchial cells. Accordingly, we determined the cytotoxicity and clastogenicity of both particulate (water-insoluble) and soluble DU in human bronchial fibroblasts (WTHBF-6 cells). We used uranium trioxide (UO3) and uranyl acetate (UA) as prototypical particulate and soluble DU salts, respectively. After a 24 h exposure, both UO3 and UA induced concentration-dependent cytotoxicity in WTHBF-6 cells. Specifically, 0.1, 0.5, 1, and 5 Î¼g/cm2 UO3 induced 99, 57, 32, and 1% relative survival, respectively. Similarly, 100, 200, 400, and 800 Î¼M UA induced 98, 92, 70, and 56% relative survival, respectively. When treated with chronic exposure, up to 72 h, of either UO3 or UA, there was an increased degree of cytotoxicity. We assessed the clastogenicity of these compounds and found that at concentrations of 0, 0.5, 1, and 5 Î¼g/cm2 UO3, 5, 6, 10, and 15% of metaphase cells exhibit some form of chromosome damage. UA did not induce chromosome damage above background levels. There were slight increases in chromosome damage induced when we extended the UO3 treatment time to 48 or 72 h, but no meaningful increase in chromosome damage was observed with chronic exposure to UA."
406733,Thompson et al. 2007,Dosage-Dependent Proteome Response of Shewanella oneidensis MR-1 to Acute Chromate Challenge,"Proteome alterations in the metal-reducing bacterium Shewanella oneidensis MR-1 in response to different acute dose challenges (0.3, 0.5, or 1 mM) of the toxic metal chromate [Cr(VI)] were characterized with multidimensional HPLCâˆ’MS/MS. Proteome measurements were performed and compared on both quadrupole ion traps as well as linear trapping quadrupole mass spectrometers. We have found that the implementation of multidimensional liquid chromatography on-line with the rapid scanning, high throughput linear trapping quadrupole platform resulted in a dramatic increase in the number of measured peptides and, thus, the number of identified proteins. A total of 2406 functionally diverse, nonredundant proteins were identified in this study, representing a relatively deep proteome coverage for this organism. The core molecular response to chromate challenge under all three concentrations consisted predominantly of proteins with annotated functions in transport and binding (e.g., components of the TonB1 iron transport system, TonB-dependent receptors, and sulfate transporters) as well as a functionally undefined DNA-binding response regulator (SO2426) that might play a role in mediating metal stress responses. In addition, proteins annotated as a cytochrome c, a putative azoreductase, and various proteins involved in general stress protection were up-regulated at the higher Cr(VI) doses (0.5 and 1 mM) only. Proteins down-regulated in response to metal treatment were distributed across diverse functional categories, with energy metabolism proteins dominating. The results presented in this work demonstrate the dynamic dosage response of S. oneidensis to sub-toxic levels of chromate. Keywords: mass spectrometry â€¢ multidimensional liquid chromatography â€¢ shotgun proteomics â€¢ Shewanella oneidensis â€¢ linear trapping quadrupole â€¢ chromate stress","Dosage-Dependent Proteome Response of Shewanella oneidensis MR-1 to Acute Chromate Challenge Abs: Proteome alterations in the metal-reducing bacterium Shewanella oneidensis MR-1 in response to different acute dose challenges (0.3, 0.5, or 1 mM) of the toxic metal chromate [Cr(VI)] were characterized with multidimensional HPLCâˆ’MS/MS. Proteome measurements were performed and compared on both quadrupole ion traps as well as linear trapping quadrupole mass spectrometers. We have found that the implementation of multidimensional liquid chromatography on-line with the rapid scanning, high throughput linear trapping quadrupole platform resulted in a dramatic increase in the number of measured peptides and, thus, the number of identified proteins. A total of 2406 functionally diverse, nonredundant proteins were identified in this study, representing a relatively deep proteome coverage for this organism. The core molecular response to chromate challenge under all three concentrations consisted predominantly of proteins with annotated functions in transport and binding (e.g., components of the TonB1 iron transport system, TonB-dependent receptors, and sulfate transporters) as well as a functionally undefined DNA-binding response regulator (SO2426) that might play a role in mediating metal stress responses. In addition, proteins annotated as a cytochrome c, a putative azoreductase, and various proteins involved in general stress protection were up-regulated at the higher Cr(VI) doses (0.5 and 1 mM) only. Proteins down-regulated in response to metal treatment were distributed across diverse functional categories, with energy metabolism proteins dominating. The results presented in this work demonstrate the dynamic dosage response of S. oneidensis to sub-toxic levels of chromate. Keywords: mass spectrometry â€¢ multidimensional liquid chromatography â€¢ shotgun proteomics â€¢ Shewanella oneidensis â€¢ linear trapping quadrupole â€¢ chromate stress"
405276,Entezari et al. 2005,Combination of Ultrasound and Discarded Tire Rubber: Removal of Cr(III) from Aqueous Solution,"Ground discarded tire rubber is an interesting and inexpensive medium for the sorption of toxic metals, including chromium, from water. The batch sorption tests were conducted to investigate the sorption capacity of Cr(III) from aqueous solution by ground tire in the presence and absence of ultrasound. The research parameters included ultrasonic waves, solution temperature, aqueous chromium concentration, particle size of the ground tire, contact time, and others. The Langmuir model was applied to the sorption equilibrium to determine the maximum metal sorption capacity in the presence and absence of ultrasound. The Langmuir constants were also obtained from the isotherms under different conditions. The results indicated that the tire rubber was a more efficient sorbent for the removal of chromium in the presence of ultrasound. Because there are several stages in the sorption process, it is important to find out which step or steps control the rate of sorption. According to the results, the internal porous diffusion is the rate-controlling step. The diffusion coefficient of Cr(III) in ground tire rubber in the presence of ultrasound was about two times greater than that in the absence of ultrasound. The effect of ultrasound on the sorption process could be explained by the thermal and nonthermal properties of acoustic cavitation.","Combination of Ultrasound and Discarded Tire Rubber: Removal of Cr(III) from Aqueous Solution Abs: Ground discarded tire rubber is an interesting and inexpensive medium for the sorption of toxic metals, including chromium, from water. The batch sorption tests were conducted to investigate the sorption capacity of Cr(III) from aqueous solution by ground tire in the presence and absence of ultrasound. The research parameters included ultrasonic waves, solution temperature, aqueous chromium concentration, particle size of the ground tire, contact time, and others. The Langmuir model was applied to the sorption equilibrium to determine the maximum metal sorption capacity in the presence and absence of ultrasound. The Langmuir constants were also obtained from the isotherms under different conditions. The results indicated that the tire rubber was a more efficient sorbent for the removal of chromium in the presence of ultrasound. Because there are several stages in the sorption process, it is important to find out which step or steps control the rate of sorption. According to the results, the internal porous diffusion is the rate-controlling step. The diffusion coefficient of Cr(III) in ground tire rubber in the presence of ultrasound was about two times greater than that in the absence of ultrasound. The effect of ultrasound on the sorption process could be explained by the thermal and nonthermal properties of acoustic cavitation."
387700,Wise et al. 2010,Comparative genotoxicity and cytotoxicity of four hexavalent chromium compounds in human bronchial cells,"Hexavalent chromium (Cr(VI)) compounds are well-established human lung carcinogens. Solubility plays an important role in their carcinogenicity with the particulate Cr(VI) compounds being the most carcinogenic. Epidemiology and animal studies suggest that zinc chromate is the most potent particulate Cr(VI) compound; however, there are few comparative data to support these observations. The purpose of this study was to compare the genotoxicity of zinc chromate with two other particulate Cr(VI) compounds, barium chromate and lead chromate, and one soluble Cr(VI) compound, sodium chromate. The clastogenic effects of barium chromate and zinc chromate were similar, but lead chromate induced significantly less damage. The levels of DNA damage measured by gamma-H2A.X foci formation were similar for the three particulate chromium compounds. Corrected for chromium uptake differences, we found that zinc chromate and barium chromate were the most cytotoxic, and lead chromate and sodium chromate were less cytotoxic. Zinc chromate was more clastogenic than all other chromium compounds, and lead chromate was the least clastogenic. There was no significant difference between any of the compounds for the induction of DNA double strand breaks. All together, these data suggest that the difference in the carcinogenic potency of zinc chromate over the other chromium compounds is not due solely to a difference in chromium ion uptake and that the zinc cation may in fact have an important role in its carcinogenicity.","Comparative genotoxicity and cytotoxicity of four hexavalent chromium compounds in human bronchial cells Abs: Hexavalent chromium (Cr(VI)) compounds are well-established human lung carcinogens. Solubility plays an important role in their carcinogenicity with the particulate Cr(VI) compounds being the most carcinogenic. Epidemiology and animal studies suggest that zinc chromate is the most potent particulate Cr(VI) compound; however, there are few comparative data to support these observations. The purpose of this study was to compare the genotoxicity of zinc chromate with two other particulate Cr(VI) compounds, barium chromate and lead chromate, and one soluble Cr(VI) compound, sodium chromate. The clastogenic effects of barium chromate and zinc chromate were similar, but lead chromate induced significantly less damage. The levels of DNA damage measured by gamma-H2A.X foci formation were similar for the three particulate chromium compounds. Corrected for chromium uptake differences, we found that zinc chromate and barium chromate were the most cytotoxic, and lead chromate and sodium chromate were less cytotoxic. Zinc chromate was more clastogenic than all other chromium compounds, and lead chromate was the least clastogenic. There was no significant difference between any of the compounds for the induction of DNA double strand breaks. All together, these data suggest that the difference in the carcinogenic potency of zinc chromate over the other chromium compounds is not due solely to a difference in chromium ion uptake and that the zinc cation may in fact have an important role in its carcinogenicity."
387041,Tubek et al. 2010,"The Content of Elements in Rainwater and its Relation to the Frequency of Hospitalization for Atrial Fibrillation in Opole Voivodship, Poland, During 2000-2002","The elemental composition of rainwater is a suitable indirect indicator of the presence of chemical elements in airborne dust. As such, rainwater is considered a suitable monitor for environmental or natural pollution. The yearly content of chemical elements in rainwater may be considered a good indicator for determining the influence of these environmental factors on human body. We decided to investigate the relationship between chemical elements in rainwater and the frequency of hospitalizations for atrial fibrillation (I48, ICD10) on the population of the region of Opole Voivodship, Poland during the years 2000-2002. The voivodship or province has a population of one million and is divided into 12 counties that have between 44,000 and 151,000 inhabitants. We calculated the yearly average number of hospitalizations by reasons of atrial fibrillation per 10,000 inhabitants in particular counties. The average content of the chosen chemical elements in kilograms per hectare per year was calculated for each county individually and the data evaluated by means of Spearman's correlation coefficient. There is a high positive correlation between chromium in rainwater and hospital admissions for atrial fibrillation (r = 0.62) and mild positive correlation with cadmium (r = 0.57), lead (r = 0.57), zinc (r = 0.50), and chloride (r = 0.48). There are no significant differences between male and female patients. The biological activities of these elements, which may include enhanced adrenergic stimulation, remodeling of calcium or other ion channels, or the cytotoxic effects of hexavalent chromium may explain the positive correlations here reported.","The Content of Elements in Rainwater and its Relation to the Frequency of Hospitalization for Atrial Fibrillation in Opole Voivodship, Poland, During 2000-2002 Abs: The elemental composition of rainwater is a suitable indirect indicator of the presence of chemical elements in airborne dust. As such, rainwater is considered a suitable monitor for environmental or natural pollution. The yearly content of chemical elements in rainwater may be considered a good indicator for determining the influence of these environmental factors on human body. We decided to investigate the relationship between chemical elements in rainwater and the frequency of hospitalizations for atrial fibrillation (I48, ICD10) on the population of the region of Opole Voivodship, Poland during the years 2000-2002. The voivodship or province has a population of one million and is divided into 12 counties that have between 44,000 and 151,000 inhabitants. We calculated the yearly average number of hospitalizations by reasons of atrial fibrillation per 10,000 inhabitants in particular counties. The average content of the chosen chemical elements in kilograms per hectare per year was calculated for each county individually and the data evaluated by means of Spearman's correlation coefficient. There is a high positive correlation between chromium in rainwater and hospital admissions for atrial fibrillation (r = 0.62) and mild positive correlation with cadmium (r = 0.57), lead (r = 0.57), zinc (r = 0.50), and chloride (r = 0.48). There are no significant differences between male and female patients. The biological activities of these elements, which may include enhanced adrenergic stimulation, remodeling of calcium or other ion channels, or the cytotoxic effects of hexavalent chromium may explain the positive correlations here reported."
381909,Holmes et al. 2010,Chronic Exposure to Zinc Chromate Induces Centrosome Amplification and Spindle Assembly Checkpoint Bypass in Human Lung Fibroblasts,"Hexavalent chromium (Cr(VI)) compounds are known human lung carcinogens. Solubility plays an important role ill its carcinogenicity with the particulate or insoluble form being the most potent. Of the particulate Cr(VI) compounds, zinc chromate appears to be the most potent carcinogen; however, very few studies have investigated its carcinogenic mechanism. In this study, we investigated the ability of chronic exposure to zinc chromate to induce numerical chromosome instability. We found no increase in aneuploidy after a 24 h exposure to zinc chromate, but with more chronic exposures, zinc chromate induced concentration- and time-dependent increases in aneuploidy ill the form of hypodiploidy, hyperdiploidy, and tetraploidy. Zinc chromate also induced centrosome amplification in a concentration- and time-dependent manner in both interphase and mitotic cells after chronic exposure, producing cells with centriolar defects. Furthermore, chronic exposure to zinc chromate induced concentration- and time-dependent increases in spindle assembly checkpoint bypass with increases ill centromere spreading, premature centromere division, and premature anaphase. Last, we found that chronic exposure to zinc chromate induced a G2 arrest. All together, these data indicate that zinc chromate can induce chromosome instability after prolonged exposures.","Chronic Exposure to Zinc Chromate Induces Centrosome Amplification and Spindle Assembly Checkpoint Bypass in Human Lung Fibroblasts Abs: Hexavalent chromium (Cr(VI)) compounds are known human lung carcinogens. Solubility plays an important role ill its carcinogenicity with the particulate or insoluble form being the most potent. Of the particulate Cr(VI) compounds, zinc chromate appears to be the most potent carcinogen; however, very few studies have investigated its carcinogenic mechanism. In this study, we investigated the ability of chronic exposure to zinc chromate to induce numerical chromosome instability. We found no increase in aneuploidy after a 24 h exposure to zinc chromate, but with more chronic exposures, zinc chromate induced concentration- and time-dependent increases in aneuploidy ill the form of hypodiploidy, hyperdiploidy, and tetraploidy. Zinc chromate also induced centrosome amplification in a concentration- and time-dependent manner in both interphase and mitotic cells after chronic exposure, producing cells with centriolar defects. Furthermore, chronic exposure to zinc chromate induced concentration- and time-dependent increases in spindle assembly checkpoint bypass with increases ill centromere spreading, premature centromere division, and premature anaphase. Last, we found that chronic exposure to zinc chromate induced a G2 arrest. All together, these data indicate that zinc chromate can induce chromosome instability after prolonged exposures."
379995,Chun et al. 2010,Polo-like kinase 1 enhances survival and mutagenesis after genotoxic stress in normal cells through cell cycle checkpoint bypass,"Polo-like kinase 1 (Plk1) is a key regulator of mitosis. Aberrant Plk1 activity is found in tumors, but little is known regarding its role in the DNA damage response of normal cells and its potential contribution to the early stages of carcinogenesis. Inappropriate survival signaling after DNA damage may facilitate clonal expansion of genetically compromised cells, and it is known that protein tyrosine phosphatase (PTP) inhibitors activate key survival pathways. In this study we employed hexavalent chromium [Cr(VI)], a well-documented genotoxicant, to investigate the mechanism by which survival pathway activation could lead to loss of checkpoint control via a mechanism involving Plk1. We recently reported that PTP inhibition enhances clonogenic survival and mutagenesis after Cr(VI) exposure by overriding Cr-induced growth arrest. Here, we report that checkpoint bypass, facilitated by PTP inhibition, was associated with decreased Cdk1 Tyr15 phosphorylation, as well as increased Plk1 activity and nuclear localization. Plk1 was necessary for increased survival after PTP inhibition and Cr(VI) exposure in normal human fibroblasts via enhanced mitotic progression. In addition, pharmacological inhibition of Plk1 abolished the PTP inhibitor-induced bypass of the G2/M checkpoint. Notably, Plk1 overexpression increased survival and mutagenesis after Cr(VI) exposure in wild-type S. cerevisiae. Taken together, our data indicate that Plk1 activation and nuclear localization are necessary for PTP-regulated mitotic progression after DNA damage. Our studies highlight a role for Plk1 in the loss of checkpoint control, increased survival, and mutagenesis after genotoxic exposure in normal cells, which in turn may lead to genomic instability and carcinogenesis.","Polo-like kinase 1 enhances survival and mutagenesis after genotoxic stress in normal cells through cell cycle checkpoint bypass Abs: Polo-like kinase 1 (Plk1) is a key regulator of mitosis. Aberrant Plk1 activity is found in tumors, but little is known regarding its role in the DNA damage response of normal cells and its potential contribution to the early stages of carcinogenesis. Inappropriate survival signaling after DNA damage may facilitate clonal expansion of genetically compromised cells, and it is known that protein tyrosine phosphatase (PTP) inhibitors activate key survival pathways. In this study we employed hexavalent chromium [Cr(VI)], a well-documented genotoxicant, to investigate the mechanism by which survival pathway activation could lead to loss of checkpoint control via a mechanism involving Plk1. We recently reported that PTP inhibition enhances clonogenic survival and mutagenesis after Cr(VI) exposure by overriding Cr-induced growth arrest. Here, we report that checkpoint bypass, facilitated by PTP inhibition, was associated with decreased Cdk1 Tyr15 phosphorylation, as well as increased Plk1 activity and nuclear localization. Plk1 was necessary for increased survival after PTP inhibition and Cr(VI) exposure in normal human fibroblasts via enhanced mitotic progression. In addition, pharmacological inhibition of Plk1 abolished the PTP inhibitor-induced bypass of the G2/M checkpoint. Notably, Plk1 overexpression increased survival and mutagenesis after Cr(VI) exposure in wild-type S. cerevisiae. Taken together, our data indicate that Plk1 activation and nuclear localization are necessary for PTP-regulated mitotic progression after DNA damage. Our studies highlight a role for Plk1 in the loss of checkpoint control, increased survival, and mutagenesis after genotoxic exposure in normal cells, which in turn may lead to genomic instability and carcinogenesis."
379697,Cecen et al. 2010,"Inhibition of respiration and distribution of Cd, Pb, Hg, Ag and Cr species in a nitrifying sludge","The study investigated the inhibitory effects of the heavy metals Cd, Pb, Hg, Ag and Cr (as Cr(3+) and Cr(6+)) on a nitrifying sludge. The aim was to assess the IC(50) concentrations leading to 50% inhibition. The method is based on respiration of nitrifying sludge in the presence of these metals. Both O(2) consumption and CO(2) production were taken into account. The order of the inhibitory effect was Ag>Hg>Cd>Cr(3+)=Cr(6+). Metal speciation was calculated in terms of free metal, inorganic metal complexes and bound metal. Pb largely precipitated and 50% inhibition was never reached. Ag was always in the form of the free ion or labile complexes. Hg had apparently a lower toxicity than Ag, since most of it was initially highly complexed with ammonia. Cd was present in the form of free ion and complexes which caused inhibition although a large part of them were precipitated. The inhibitory effects of trivalent chromium (Cr(3+)) and hexavalent chromium (Cr(6+)) were similar. The latter was present in the form of the anion CrO(4)(2-) and was not taken up by biomass. The study highlighted that IC(50) values alone do not have an explanatory power of inhibition unless speciation is also considered.","Inhibition of respiration and distribution of Cd, Pb, Hg, Ag and Cr species in a nitrifying sludge Abs: The study investigated the inhibitory effects of the heavy metals Cd, Pb, Hg, Ag and Cr (as Cr(3+) and Cr(6+)) on a nitrifying sludge. The aim was to assess the IC(50) concentrations leading to 50% inhibition. The method is based on respiration of nitrifying sludge in the presence of these metals. Both O(2) consumption and CO(2) production were taken into account. The order of the inhibitory effect was Ag>Hg>Cd>Cr(3+)=Cr(6+). Metal speciation was calculated in terms of free metal, inorganic metal complexes and bound metal. Pb largely precipitated and 50% inhibition was never reached. Ag was always in the form of the free ion or labile complexes. Hg had apparently a lower toxicity than Ag, since most of it was initially highly complexed with ammonia. Cd was present in the form of free ion and complexes which caused inhibition although a large part of them were precipitated. The inhibitory effects of trivalent chromium (Cr(3+)) and hexavalent chromium (Cr(6+)) were similar. The latter was present in the form of the anion CrO(4)(2-) and was not taken up by biomass. The study highlighted that IC(50) values alone do not have an explanatory power of inhibition unless speciation is also considered."
363364,Rahman et al. 2005,Determination of hexavalent chromium by using speciated isotope-dilution mass spectrometry after microwave speciated extraction of environmental and other solid materials,"Precise and accurate determination of hexavalent chromium in different types of solid environmental sample is regarded as a technical challenge with significant potential error if historically accepted methods are used. Microwave-assisted alkaline extraction (0.5 mol L-1 NaOH+0.28 mol L-1 Na2CO3) followed by anion-exchange chromatographic separation and inductively coupled plasma mass spectrophotometric detection has been shown to provide accurate and precise results. To obtain a better understanding of potential species conversion during and/or after extraction steps, speciated isotope-dilution mass spectrometry (SIDMS) (EPA Method 6800) metrology has been successfully applied as a diagnostic tool with the modified accompanying extraction version of EPA Method 3060A. In our study, aggregate materials distributed over a large area of a major western US state were found to contain a high concentration of total chromium (195Ã‚Â±13 to 709Ã‚Â±19 Ã‚Âµg g-1) and significant amounts of Cr6+ (141Ã‚Â±6 to 341Ã‚Â±29 Ã‚Âµg g-1) which are at least three orders of magnitude higher than the US EPA threshold limit (0.5 Ã‚Âµg g-1). Sediment samples from a major western US state, studied independently, were found to contain less (1.77Ã‚Â±0.34 Ã‚Âµg g-1) or no Cr6+ in the presence of significant total chromium.","Determination of hexavalent chromium by using speciated isotope-dilution mass spectrometry after microwave speciated extraction of environmental and other solid materials Abs: Precise and accurate determination of hexavalent chromium in different types of solid environmental sample is regarded as a technical challenge with significant potential error if historically accepted methods are used. Microwave-assisted alkaline extraction (0.5 mol L-1 NaOH+0.28 mol L-1 Na2CO3) followed by anion-exchange chromatographic separation and inductively coupled plasma mass spectrophotometric detection has been shown to provide accurate and precise results. To obtain a better understanding of potential species conversion during and/or after extraction steps, speciated isotope-dilution mass spectrometry (SIDMS) (EPA Method 6800) metrology has been successfully applied as a diagnostic tool with the modified accompanying extraction version of EPA Method 3060A. In our study, aggregate materials distributed over a large area of a major western US state were found to contain a high concentration of total chromium (195Ã‚Â±13 to 709Ã‚Â±19 Ã‚Âµg g-1) and significant amounts of Cr6+ (141Ã‚Â±6 to 341Ã‚Â±29 Ã‚Âµg g-1) which are at least three orders of magnitude higher than the US EPA threshold limit (0.5 Ã‚Âµg g-1). Sediment samples from a major western US state, studied independently, were found to contain less (1.77Ã‚Â±0.34 Ã‚Âµg g-1) or no Cr6+ in the presence of significant total chromium."
360849,Krishnani et al. 2009,Metal ions binding onto lignocellulosic biosorbent,"This paper describes the use of a lignocellulosic biosorbent for the adsorption and ion exchange of nine different heavy metals ions. Batch isothermal equilibrium and continuous column adsorption experiments were carried out in an effort to evaluate the maximum adsorption capacity, pH dependence and to study the mechanism of removal of metal ions onto the biosorbent. Bio-sorption data were interpreted using Langmuir isotherm which reflect the influence of metal concentration on the uptake of the metal ion. Potentiometric titrations were used to determine the contents of total functional groups. The biosorbent showed the strongest affinity for Pb2+, Hg2+ and Cu2+. The metal ions such as Cd2+, Cu2+, Ni2+, Co2+, and Mn2+ seemed to be exclusively involved in ion-exchange mechanism with Ca2+ ions. The column adsorption experiment of multiple metals revealed the role of another cation in effective removal of Pb2+, Hg2+ and Zn2+. The biosorbent has been found to be a good electron donor for the reduction of Cr(VI) in an acidic medium.","Metal ions binding onto lignocellulosic biosorbent Abs: This paper describes the use of a lignocellulosic biosorbent for the adsorption and ion exchange of nine different heavy metals ions. Batch isothermal equilibrium and continuous column adsorption experiments were carried out in an effort to evaluate the maximum adsorption capacity, pH dependence and to study the mechanism of removal of metal ions onto the biosorbent. Bio-sorption data were interpreted using Langmuir isotherm which reflect the influence of metal concentration on the uptake of the metal ion. Potentiometric titrations were used to determine the contents of total functional groups. The biosorbent showed the strongest affinity for Pb2+, Hg2+ and Cu2+. The metal ions such as Cd2+, Cu2+, Ni2+, Co2+, and Mn2+ seemed to be exclusively involved in ion-exchange mechanism with Ca2+ ions. The column adsorption experiment of multiple metals revealed the role of another cation in effective removal of Pb2+, Hg2+ and Zn2+. The biosorbent has been found to be a good electron donor for the reduction of Cr(VI) in an acidic medium."
359676,Hassan et al. 2005,"Flow injection fluorimetric determination of chromium(VI) in electroplating baths by luminescence quenching of tris(2,2'-bipyridyl) ruthenium(II)","A sensitive and selective luminescence quenching method is developed and used for manual and flow injection analysis (FIA) of chromium(VI) by reaction with [Ru(bpy)3]2+. The emission peak of ruthenium(II) at 595 nm is linearly decreased as a function of Cr(VI) concentration. This permits determination of chromium(VI) ion over the concentration range 0.1-20 Ã‚Âµg ml-1 with a detection limit of 33 ng ml-1. The quenching process is due to an electron transfer from the luminescent [Ru(bpy)3]2+ complex ion to Cr(VI) resulting in the formation of the non-luminescent [Ru(bpy)3]3+ complex ion. Selectivity for Cr(VI) over many anions and transition, alkali and alkaline earth metal cations is demonstrated. High concentration levels of sulphate, chloride, borate, acetate, phosphate, nitrate, cyanide, Pb2+, Zn2+, Hg2+, Cu2+, Cd2+, Ni2+ and Mn2+ ions are tolerated. The effects of solution pH and [Ru(bpy)3]2+ reagent concentration are examined and the reaction conditions are optimized. Validation of the method according to the quality assurance standards show suitability of the proposed method for use in the quality control assessment of Cr(VI) in complex matrices without prior treatment. The method is successfully applied to determine chromium(VI) in electroplating baths using flow injection analysis. Results with a mean standard deviation of Ã‚Â±0.6% are obtained which compare fairly well with data obtained using atomic absorption spectrometry.","Flow injection fluorimetric determination of chromium(VI) in electroplating baths by luminescence quenching of tris(2,2'-bipyridyl) ruthenium(II) Abs: A sensitive and selective luminescence quenching method is developed and used for manual and flow injection analysis (FIA) of chromium(VI) by reaction with [Ru(bpy)3]2+. The emission peak of ruthenium(II) at 595 nm is linearly decreased as a function of Cr(VI) concentration. This permits determination of chromium(VI) ion over the concentration range 0.1-20 Ã‚Âµg ml-1 with a detection limit of 33 ng ml-1. The quenching process is due to an electron transfer from the luminescent [Ru(bpy)3]2+ complex ion to Cr(VI) resulting in the formation of the non-luminescent [Ru(bpy)3]3+ complex ion. Selectivity for Cr(VI) over many anions and transition, alkali and alkaline earth metal cations is demonstrated. High concentration levels of sulphate, chloride, borate, acetate, phosphate, nitrate, cyanide, Pb2+, Zn2+, Hg2+, Cu2+, Cd2+, Ni2+ and Mn2+ ions are tolerated. The effects of solution pH and [Ru(bpy)3]2+ reagent concentration are examined and the reaction conditions are optimized. Validation of the method according to the quality assurance standards show suitability of the proposed method for use in the quality control assessment of Cr(VI) in complex matrices without prior treatment. The method is successfully applied to determine chromium(VI) in electroplating baths using flow injection analysis. Results with a mean standard deviation of Ã‚Â±0.6% are obtained which compare fairly well with data obtained using atomic absorption spectrometry."
353672,Tacon and  Metian 2008,Aquaculture feed and food safety: the role of the food and agriculture organization and the Codex Alimentarius,"The ultimate objective of an aquaculture feed manufacturer and aquaculture food supplier is to ensure that the feed or food produced is both safe and wholesome. Reported food safety risks, which may be associated with the use of commercial animal feeds, including compound aquaculture feeds, usually result from the possible presence of unwanted contaminants, either within the feed ingredients used or from the external contamination of the finished feed on prolonged storage. The major animal feed contaminants that have been reported to date have included Salmonellae, mycotoxins, veterinary drug residues, persistent organic pollutants, agricultural and other chemicals (solvent residues, melamine), heavy metals (mercury, lead, cadmium) and excess mineral salts (hexavalent chromium, arsenic, selenium, flourine), and transmissible spongiform encephalopathies. Apart from the direct negative effect of these possible contaminants on the health of the cultured target species, there is a risk that the feed contaminants may be passed along the food chain, via contaminated aquaculture produce, to consumers. In recent years, public concern regarding food safety has increased as a consequence of the increasing prevalence of antibiotic residues, persistent organic pollutants, and chemicals in farmed seafood. The important role played by the Food and Agriculture Organization of the United Nations (FAO) and the Codex Alimentarius Commission in the development of international standards, guidelines, and recommendations to protect the health of consumers and ensure fair practices in the food trade is discussed.","Aquaculture feed and food safety: the role of the food and agriculture organization and the Codex Alimentarius Abs: The ultimate objective of an aquaculture feed manufacturer and aquaculture food supplier is to ensure that the feed or food produced is both safe and wholesome. Reported food safety risks, which may be associated with the use of commercial animal feeds, including compound aquaculture feeds, usually result from the possible presence of unwanted contaminants, either within the feed ingredients used or from the external contamination of the finished feed on prolonged storage. The major animal feed contaminants that have been reported to date have included Salmonellae, mycotoxins, veterinary drug residues, persistent organic pollutants, agricultural and other chemicals (solvent residues, melamine), heavy metals (mercury, lead, cadmium) and excess mineral salts (hexavalent chromium, arsenic, selenium, flourine), and transmissible spongiform encephalopathies. Apart from the direct negative effect of these possible contaminants on the health of the cultured target species, there is a risk that the feed contaminants may be passed along the food chain, via contaminated aquaculture produce, to consumers. In recent years, public concern regarding food safety has increased as a consequence of the increasing prevalence of antibiotic residues, persistent organic pollutants, and chemicals in farmed seafood. The important role played by the Food and Agriculture Organization of the United Nations (FAO) and the Codex Alimentarius Commission in the development of international standards, guidelines, and recommendations to protect the health of consumers and ensure fair practices in the food trade is discussed."
345857,Bataineh et al. 2007,Short-term exposure of female rats to industrial metal salts: Effect on implantation and pregnancy,"Aim: The objective of this study was to characterize the adverse effects of industrial metal salts during the early stages of pregnancy. Methods: Successfully mated female rats were exposed to the following metal salts via intragastric intubation; manganese sulfate, lead acetate, aluminum chloride, ferrous chloride and ferric chloride in doses of 50 mg/kg body weight and chromium chloride and potassium dichromate in doses of 25 mg/kg body weight on days l-3 or 4-6 of pregnancy. Female rats were killed on day 20 of gestation and the pregnancy outcome was determined. Results: The administration of manganese sulfate, chromium chloride, potassium dichromate and ferric chloride to female rats on days 1-3 of pregnancy caused pregnancy failure. However, the administration of manganese sulfate and potassium dichromate reduced the number of implantations. The administration of manganese sulfate, potassium dichromate and ferric chloride reduced the number of viable fetuses. The total number of resorptions increased in the lead acetate, aluminum chloride, ferrous chloride and ferric chloride exposed groups. In contrast, the administration of manganese sulfate, aluminum chloride and ferric chloride on days 4-6 of pregnancy caused pregnancy failure. However, the administration of ferric chloride reduced the number of implantations. The administration of manganese sulfate, aluminum chloride, potassium dichromate, ferrous chloride and ferric chloride reduced the number of viable fetuses. The total number of resorptions increased in the manganese sulfate, lead acetate, aluminum chloride, potassium dichromate, ferrous chloride and ferric chloride exposed groups. Conclusion: This work demonstrates that the short-term exposure of female rats to industrial metal salts during the early stages of gestation would cause failure of pregnancy and produce fetotoxic or fetal resorptive potentials. (Reprod Med Biol 2007; 6: 179-183)","Short-term exposure of female rats to industrial metal salts: Effect on implantation and pregnancy Abs: Aim: The objective of this study was to characterize the adverse effects of industrial metal salts during the early stages of pregnancy. Methods: Successfully mated female rats were exposed to the following metal salts via intragastric intubation; manganese sulfate, lead acetate, aluminum chloride, ferrous chloride and ferric chloride in doses of 50 mg/kg body weight and chromium chloride and potassium dichromate in doses of 25 mg/kg body weight on days l-3 or 4-6 of pregnancy. Female rats were killed on day 20 of gestation and the pregnancy outcome was determined. Results: The administration of manganese sulfate, chromium chloride, potassium dichromate and ferric chloride to female rats on days 1-3 of pregnancy caused pregnancy failure. However, the administration of manganese sulfate and potassium dichromate reduced the number of implantations. The administration of manganese sulfate, potassium dichromate and ferric chloride reduced the number of viable fetuses. The total number of resorptions increased in the lead acetate, aluminum chloride, ferrous chloride and ferric chloride exposed groups. In contrast, the administration of manganese sulfate, aluminum chloride and ferric chloride on days 4-6 of pregnancy caused pregnancy failure. However, the administration of ferric chloride reduced the number of implantations. The administration of manganese sulfate, aluminum chloride, potassium dichromate, ferrous chloride and ferric chloride reduced the number of viable fetuses. The total number of resorptions increased in the manganese sulfate, lead acetate, aluminum chloride, potassium dichromate, ferrous chloride and ferric chloride exposed groups. Conclusion: This work demonstrates that the short-term exposure of female rats to industrial metal salts during the early stages of gestation would cause failure of pregnancy and produce fetotoxic or fetal resorptive potentials. (Reprod Med Biol 2007; 6: 179-183)"
217515,Wise et al. 2008,Hexavalent chromium-induced DNA damage and repair mechanisms,"Hexavalent chromium is a commonly used industrial metal that has been shown to induce lung cancer in workers having long term exposure. In the particulate form, Cr(VI) dissolves slowly in vivo, leading to an extended exposure of lung cells. Hexavalent chromium is taken into the cell and rapidly reduced to Cr(V), Cr(IV), Cr(III), and reactive oxygen species. Cells treated with Cr(VI) are subject to several types of DNA damage resulting from this reduction, including base modification, single-strand breaks, double-strand breaks, Cr-DNA adducts, DNA-Cr-DNA adducts, and protein-Cr-DNA adducts. These types of damage, if left unrepaired or are misrepaired, can lead to growth arrest, cytotoxicity, and apoptosis, as well as mutations leading to neoplastic transformation and ultimately tumorigenesis. Here we review the current literature on Cr-induced DNA damage and its repair.","Hexavalent chromium-induced DNA damage and repair mechanisms Abs: Hexavalent chromium is a commonly used industrial metal that has been shown to induce lung cancer in workers having long term exposure. In the particulate form, Cr(VI) dissolves slowly in vivo, leading to an extended exposure of lung cells. Hexavalent chromium is taken into the cell and rapidly reduced to Cr(V), Cr(IV), Cr(III), and reactive oxygen species. Cells treated with Cr(VI) are subject to several types of DNA damage resulting from this reduction, including base modification, single-strand breaks, double-strand breaks, Cr-DNA adducts, DNA-Cr-DNA adducts, and protein-Cr-DNA adducts. These types of damage, if left unrepaired or are misrepaired, can lead to growth arrest, cytotoxicity, and apoptosis, as well as mutations leading to neoplastic transformation and ultimately tumorigenesis. Here we review the current literature on Cr-induced DNA damage and its repair."
211099,Smith 2008,"Hexavalent chromium, yellow water, and cancer: a convoluted saga.[comment]","In this issue, Beaumont et al report cancer mortality rates associated with exposure to high concentrations of hexavalent chromium in well water in Liaoning Province, China. Contamination of drinking water at these levels has been reported only once before, among a small group in Mexico. The investigation in China is a convoluted tale. The first report indicated an increase in cancer mortality, while a subsequent publication with the same lead author claimed no increased risks. In 2006, the journal publishing the latter paper retracted it because of failure to disclose financial and intellectual input to the paper by outside parties (linked to chromium polluting industries). Beaumont and his colleagues now provide a further reanalysis of these data, showing increased mortality in particular from stomach cancer, but with serious limitations in the data and methods of analysis. These limitations are counterbalanced by the importance of a study of perhaps the highest exposure to hexavalent chromium in water that will ever be experienced by a population large enough to estimate risks of cancer.","Hexavalent chromium, yellow water, and cancer: a convoluted saga.[comment] Abs: In this issue, Beaumont et al report cancer mortality rates associated with exposure to high concentrations of hexavalent chromium in well water in Liaoning Province, China. Contamination of drinking water at these levels has been reported only once before, among a small group in Mexico. The investigation in China is a convoluted tale. The first report indicated an increase in cancer mortality, while a subsequent publication with the same lead author claimed no increased risks. In 2006, the journal publishing the latter paper retracted it because of failure to disclose financial and intellectual input to the paper by outside parties (linked to chromium polluting industries). Beaumont and his colleagues now provide a further reanalysis of these data, showing increased mortality in particular from stomach cancer, but with serious limitations in the data and methods of analysis. These limitations are counterbalanced by the importance of a study of perhaps the highest exposure to hexavalent chromium in water that will ever be experienced by a population large enough to estimate risks of cancer."
201917,Akar et al. 2006,Biosorption potential of the macrofungus Ganoderma carnosum for removal of lead(II) ions from aqueous solutions,"This paper reports the utilization of a macro-fungus Ganoderma carnosum as a biosorbent material for the removal of lead(II) ions from aqueous solutions. The biosorption potential of G. carnosum was investigated by batch experiments. The influences of physico-chemical parameters like pH, biosorbent dosage, contact time and initial metal ion concentration were evaluated. The biosorption equilibrium was attained in 10 minutes. Equilibrium biosorption data were analyzed by the Freundlich, Langmuir and Dubinin-Radushkevich (D-R) isotherm models. Maximum biosorption capacity of biosorbent was found to be 22.79 mg g(-1) (1.10 x 10(-4) mol g(-1)) at the pH value of 5.0. The biosorbent was regenerated using 10 mM HCl solution, with up to 96% recovery, and reused four times in biosorption-desorption cycles successively. Biosorption efficiency of G. carnosum was also examined in a real effluent. The mechanism of the biosorption was investigated with FTIR, SEM and EDAX analysis and the findings suggested that the biosorption process involved in ion exchange as dominant mechanism as well as complexation. The ion exchange mechanism was also confirmed by the mean free energy value obtained from D-R isotherm model.","Biosorption potential of the macrofungus Ganoderma carnosum for removal of lead(II) ions from aqueous solutions Abs: This paper reports the utilization of a macro-fungus Ganoderma carnosum as a biosorbent material for the removal of lead(II) ions from aqueous solutions. The biosorption potential of G. carnosum was investigated by batch experiments. The influences of physico-chemical parameters like pH, biosorbent dosage, contact time and initial metal ion concentration were evaluated. The biosorption equilibrium was attained in 10 minutes. Equilibrium biosorption data were analyzed by the Freundlich, Langmuir and Dubinin-Radushkevich (D-R) isotherm models. Maximum biosorption capacity of biosorbent was found to be 22.79 mg g(-1) (1.10 x 10(-4) mol g(-1)) at the pH value of 5.0. The biosorbent was regenerated using 10 mM HCl solution, with up to 96% recovery, and reused four times in biosorption-desorption cycles successively. Biosorption efficiency of G. carnosum was also examined in a real effluent. The mechanism of the biosorption was investigated with FTIR, SEM and EDAX analysis and the findings suggested that the biosorption process involved in ion exchange as dominant mechanism as well as complexation. The ion exchange mechanism was also confirmed by the mean free energy value obtained from D-R isotherm model."
201827,Waters et al. 1999,Genetic toxicology data in the evaluation of potential human environmental carcinogens,"In 1969, the International Agency for Research on Cancer (IARC) initiated the Monographs Programme to evaluate the carcinogenic risk of chemicals to humans. Results from short-term mutagenicity tests were first included in the IARC Monographs in the mid-1970s based on the observation that most carcinogens are also mutagens, although not all mutagens are carcinogens. Experimental evidence at that time showed a strong correlation between mutagenicity and carcinogenicity and indicated that short-term mutagenicity tests are useful for predicting carcinogenicity. Although the strength of these correlations has diminished over the past 20 years with the identification of putative nongenotoxic carcinogens, such tests provide vital information for identifying potential human carcinogens and understanding mechanisms of carcinogenesis. The short-term test results for agents compiled in the EPA/IARC Genetic Activity Profile (GAP) database over nearly 15 years are summarized and reviewed here with regard to their IARC carcinogenicity classifications. The evidence of mutagenicity or nonmutagenicity based on a 'defining set' of test results from three genetic endpoints (gene mutation, chromosomal aberrations, and aneuploidy) is examined. Recommendations are made for assessing chemicals based on the strength of evidence from short-term tests, and the implications of this approach in identifying mutational mechanisms of carcinogenesis are discussed. The role of short-term test data in influencing the overall classification of specific compounds in recent Monograph volumes is discussed, particularly with reference to studies in human populations. Ethylene oxide is cited as an example. Copyright 1999 Elsevier Science B.V.","Genetic toxicology data in the evaluation of potential human environmental carcinogens Abs: In 1969, the International Agency for Research on Cancer (IARC) initiated the Monographs Programme to evaluate the carcinogenic risk of chemicals to humans. Results from short-term mutagenicity tests were first included in the IARC Monographs in the mid-1970s based on the observation that most carcinogens are also mutagens, although not all mutagens are carcinogens. Experimental evidence at that time showed a strong correlation between mutagenicity and carcinogenicity and indicated that short-term mutagenicity tests are useful for predicting carcinogenicity. Although the strength of these correlations has diminished over the past 20 years with the identification of putative nongenotoxic carcinogens, such tests provide vital information for identifying potential human carcinogens and understanding mechanisms of carcinogenesis. The short-term test results for agents compiled in the EPA/IARC Genetic Activity Profile (GAP) database over nearly 15 years are summarized and reviewed here with regard to their IARC carcinogenicity classifications. The evidence of mutagenicity or nonmutagenicity based on a 'defining set' of test results from three genetic endpoints (gene mutation, chromosomal aberrations, and aneuploidy) is examined. Recommendations are made for assessing chemicals based on the strength of evidence from short-term tests, and the implications of this approach in identifying mutational mechanisms of carcinogenesis are discussed. The role of short-term test data in influencing the overall classification of specific compounds in recent Monograph volumes is discussed, particularly with reference to studies in human populations. Ethylene oxide is cited as an example. Copyright 1999 Elsevier Science B.V."
201375,Seoane and  Dulout 2001,"Genotoxic ability of cadmium, chromium and nickel salts studied by kinetochore staining in the cytokinesis-blocked micronucleus assay","The aneugenic and clastogenic ability of cadmium chloride(II), cadmium sulfate(II), nickel chloride(II), nickel sulfate(II), chromium chloride(III) and potassium dichromate(IV) have been evaluated through kinetochore-stained micronucleus test. Traditional genotoxicity assays evaluate DNA damage, gene mutations and chromosome breakage. However, these tests are not adequate to detect aneugenic agents that do not act directly on DNA. Staining kinetochores in the cytokinesis-blocked micronucleus assay is a useful way to discriminate between clastogens and aneuploidogens and may allow a rapid identification of aneuploidy-inducing environmental compounds. Human diploid fibroblasts (MRC-5) were employed. All compounds increased micronuclei frequency in a statistically significant way. However, increases in kinetochore-positive micronuclei frequencies were higher than in kinetochore-negative ones. The present work demonstrates the genotoxic ability of the cadmium and chromium salts studied. Aneugenic as well as clastogenic ability could be observed with this assay. Nickel salts, as it was expected because of their known weak mutagenicity, showed lower genotoxic effects than the other metal salts studied. As the test employed only allows the detection of malsegregation, it is proposed that this mechanism is at least one of those by which the tested metal salts induced aneuploidy. On the other hand, visualization of kinetochores in all experiments suggests that the compounds studied did not act by damaging these structures.","Genotoxic ability of cadmium, chromium and nickel salts studied by kinetochore staining in the cytokinesis-blocked micronucleus assay Abs: The aneugenic and clastogenic ability of cadmium chloride(II), cadmium sulfate(II), nickel chloride(II), nickel sulfate(II), chromium chloride(III) and potassium dichromate(IV) have been evaluated through kinetochore-stained micronucleus test. Traditional genotoxicity assays evaluate DNA damage, gene mutations and chromosome breakage. However, these tests are not adequate to detect aneugenic agents that do not act directly on DNA. Staining kinetochores in the cytokinesis-blocked micronucleus assay is a useful way to discriminate between clastogens and aneuploidogens and may allow a rapid identification of aneuploidy-inducing environmental compounds. Human diploid fibroblasts (MRC-5) were employed. All compounds increased micronuclei frequency in a statistically significant way. However, increases in kinetochore-positive micronuclei frequencies were higher than in kinetochore-negative ones. The present work demonstrates the genotoxic ability of the cadmium and chromium salts studied. Aneugenic as well as clastogenic ability could be observed with this assay. Nickel salts, as it was expected because of their known weak mutagenicity, showed lower genotoxic effects than the other metal salts studied. As the test employed only allows the detection of malsegregation, it is proposed that this mechanism is at least one of those by which the tested metal salts induced aneuploidy. On the other hand, visualization of kinetochores in all experiments suggests that the compounds studied did not act by damaging these structures."
201373,Seoane and  Dulout 1999,"Contribution to the validation of the anaphase-telophase test: Aneugenic and clastogenic effects of cadmium sulfate, potassium dichromate and nickel chloride in Chinese hamster ovary cells","There is increasing evidence that aneuploidy during mitosis may be a factor in the etiology of somatic malignancy. The analysis of alterations in anaphase-telophase of mitosis is a useful test for evaluating the aneuploidogenic and clastogenic ability of chemicals. Several metals have been found to be carcinogenic to humans and animals. However, the underlying mechanisms remain unclear. In the present study the aneugenic and clastogenic abilities of cadmium sulfate, potassium dichromate and nickel chloride were analyzed using the anaphase-telophase test. Chinese hamster ovary (CHO) cells cultured for two cycles were treated with the desired compound for 8 h before cell harvesting. The frequency of cells with chromatin bridges, lagging chromosomes and lagging chromosomal fragments was scored. The mitotic index was determined by counting the number of mitotic cells per 1,000 cells on each coverslip and was expressed as a percentage of the number of mitotic plates. Statistical comparisons were done using the ""G"" method. Correlation and regression analyses were performed to evaluate variations of the mitotic index. Chromium and cadmium were clastogenic and aneugenic and increased the frequencies of the three types of aberrations scored; nickel had only aneugenic activity because it increased the frequency of lagging chromosomes. These results indicate that the anaphase-telophase test is sufficiently sensitive to detect dose-response relationships that can distinguish clastogenic and/or aneugenic activities and that the results obtained using the anaphase-telophase test were similar to those obtained by chromosome counting.","Contribution to the validation of the anaphase-telophase test: Aneugenic and clastogenic effects of cadmium sulfate, potassium dichromate and nickel chloride in Chinese hamster ovary cells Abs: There is increasing evidence that aneuploidy during mitosis may be a factor in the etiology of somatic malignancy. The analysis of alterations in anaphase-telophase of mitosis is a useful test for evaluating the aneuploidogenic and clastogenic ability of chemicals. Several metals have been found to be carcinogenic to humans and animals. However, the underlying mechanisms remain unclear. In the present study the aneugenic and clastogenic abilities of cadmium sulfate, potassium dichromate and nickel chloride were analyzed using the anaphase-telophase test. Chinese hamster ovary (CHO) cells cultured for two cycles were treated with the desired compound for 8 h before cell harvesting. The frequency of cells with chromatin bridges, lagging chromosomes and lagging chromosomal fragments was scored. The mitotic index was determined by counting the number of mitotic cells per 1,000 cells on each coverslip and was expressed as a percentage of the number of mitotic plates. Statistical comparisons were done using the ""G"" method. Correlation and regression analyses were performed to evaluate variations of the mitotic index. Chromium and cadmium were clastogenic and aneugenic and increased the frequencies of the three types of aberrations scored; nickel had only aneugenic activity because it increased the frequency of lagging chromosomes. These results indicate that the anaphase-telophase test is sufficiently sensitive to detect dose-response relationships that can distinguish clastogenic and/or aneugenic activities and that the results obtained using the anaphase-telophase test were similar to those obtained by chromosome counting."
200416,Kerster and  Schaeffer 1983,Brine shrimp (Artemia salina) nauplii as a teratogen test system,"Brine shrimp increase in length rapidly after hatching. A teratogen test system is based on disruption of elongation between 24 and 48 hr after wetting of the cysts. Teratogenicity of substances dissolved in the medium is assayed by comparison of average lengths of animals raised for the test period in suspect solution with average lengths of controls. The system is fast, inexpensive, and requires little skill. Brine shrimp are suited to testing industrial wastes, chemical formulations, drugs, and food additives that can be dissolved in water at 25 degrees C. The method appears unsuited to testing the teratogenicity of gases, particulates, very dilute wastes, or natural waters. Cadmium, mercury, lead, zinc, bromoform, n-butylphthalate, 1,2-dichloroethane, nitrobenzene, tetrachloroethylene, toluene, 1,2,4-trichlorobenzene, and 1,1,3-trichloroethane were found teratogenic. Chromium (III), chromium (VI), copper, chlorobenzene, chloroform, dimethyl sulfoxide (DMSO), and phenol were found not teratogenic. Other aquatic organism teratogen test systems are surveyed","Brine shrimp (Artemia salina) nauplii as a teratogen test system Abs: Brine shrimp increase in length rapidly after hatching. A teratogen test system is based on disruption of elongation between 24 and 48 hr after wetting of the cysts. Teratogenicity of substances dissolved in the medium is assayed by comparison of average lengths of animals raised for the test period in suspect solution with average lengths of controls. The system is fast, inexpensive, and requires little skill. Brine shrimp are suited to testing industrial wastes, chemical formulations, drugs, and food additives that can be dissolved in water at 25 degrees C. The method appears unsuited to testing the teratogenicity of gases, particulates, very dilute wastes, or natural waters. Cadmium, mercury, lead, zinc, bromoform, n-butylphthalate, 1,2-dichloroethane, nitrobenzene, tetrachloroethylene, toluene, 1,2,4-trichlorobenzene, and 1,1,3-trichloroethane were found teratogenic. Chromium (III), chromium (VI), copper, chlorobenzene, chloroform, dimethyl sulfoxide (DMSO), and phenol were found not teratogenic. Other aquatic organism teratogen test systems are surveyed"
199587,Klein et al. 1991,The role of oxidative processes in metal carcinogenesis,BIOSIS COPYRIGHT: BIOL ABS. RRM REVIEW TOXICITY GENOTOXICITY MUTAGENICITY CELLULAR TRANSFORMATION DNA REPAIR NICKEL CADMIUM CHROMIUM MERCURY,The role of oxidative processes in metal carcinogenesis Abs: BIOSIS COPYRIGHT: BIOL ABS. RRM REVIEW TOXICITY GENOTOXICITY MUTAGENICITY CELLULAR TRANSFORMATION DNA REPAIR NICKEL CADMIUM CHROMIUM MERCURY
198981,Bernard and  Lauwerys 1981,The effects of sodium chromate and carbon tetrachloride on the urinary excretion and tissue distribution of cadmium in cadmium-pretreated rats,"Rats were administered nontoxic doses of Cd2+ by the oral or intraperitoneal routes. They were subsequently treated with either Na2CrO4 (10 or 20 mg/kg, sc) or CCl4 (0.5 or 1 ml/kg, intragastric). Evidence of renal damage was obtained from the determination in urine of total protein and amino acids and from the analysis of the urinary proteins by sodium dodecyl sulfate-polyacrylamide gel electrophoresis. Liver damage was evaluated by determining the serum activities of sorbitol dehydrogenase and glutamate pyruvate transaminase. The effects of CCl4 on the urinary excretion and the tissue distribution of Cd2+ vary depending on whether liver damage is associated or not with extensive renal lesions. When renal function was not or only moderately altered, induction of liver damage by CCl4 resulted in a transfer of Cd2+ from the liver to the kidney. This transfer was evidenced by a decrease of total Cd2+ as well as metallothionein-bound Cd2+ in the liver and an increase of the same parameters in the kidney. The urinary excretion of Cd2+ was only slightly increased. When liver damage induced by CCl4 was associated with extensive kidney lesions, the accumulation of Cd2+ released from the liver in the kidney was considerably reduced and large amounts of Cd2+ were excreted in urine. Administration of Na2CrO4 to Cd2+-pretreated rats gave rise to a sharp and reversible increase in the urinary excretion of Cd2+. This increase was proportional to the amount of Cd2+ stored in kidney and to the dose of Na2CrO4 administered. The Cd2+ excreted in urine originated mainly from the kidney in which total Cd2+ and metallothionein-bound Cd2+ were reduced in proportion to the dose of Na2CrO4 administered. These results suggest that two mechanisms may lead to an increased urinary excretion of Cd2+; a direct release of Cd2+ into urine from damaged kidney (i.e., Na2CrO4) or a decreased tubular reabsorption of plasma circulating Cd2+ evidenced when large amounts of Cd2+ are released into blood from damaged liver (i.e., CCl4). These results tend to support the hypothesis that kidney damage due to chronic Cd2+ poisoning may lead to an increased loss of the Cd2+ stored in the kidney.","The effects of sodium chromate and carbon tetrachloride on the urinary excretion and tissue distribution of cadmium in cadmium-pretreated rats Abs: Rats were administered nontoxic doses of Cd2+ by the oral or intraperitoneal routes. They were subsequently treated with either Na2CrO4 (10 or 20 mg/kg, sc) or CCl4 (0.5 or 1 ml/kg, intragastric). Evidence of renal damage was obtained from the determination in urine of total protein and amino acids and from the analysis of the urinary proteins by sodium dodecyl sulfate-polyacrylamide gel electrophoresis. Liver damage was evaluated by determining the serum activities of sorbitol dehydrogenase and glutamate pyruvate transaminase. The effects of CCl4 on the urinary excretion and the tissue distribution of Cd2+ vary depending on whether liver damage is associated or not with extensive renal lesions. When renal function was not or only moderately altered, induction of liver damage by CCl4 resulted in a transfer of Cd2+ from the liver to the kidney. This transfer was evidenced by a decrease of total Cd2+ as well as metallothionein-bound Cd2+ in the liver and an increase of the same parameters in the kidney. The urinary excretion of Cd2+ was only slightly increased. When liver damage induced by CCl4 was associated with extensive kidney lesions, the accumulation of Cd2+ released from the liver in the kidney was considerably reduced and large amounts of Cd2+ were excreted in urine. Administration of Na2CrO4 to Cd2+-pretreated rats gave rise to a sharp and reversible increase in the urinary excretion of Cd2+. This increase was proportional to the amount of Cd2+ stored in kidney and to the dose of Na2CrO4 administered. The Cd2+ excreted in urine originated mainly from the kidney in which total Cd2+ and metallothionein-bound Cd2+ were reduced in proportion to the dose of Na2CrO4 administered. These results suggest that two mechanisms may lead to an increased urinary excretion of Cd2+; a direct release of Cd2+ into urine from damaged kidney (i.e., Na2CrO4) or a decreased tubular reabsorption of plasma circulating Cd2+ evidenced when large amounts of Cd2+ are released into blood from damaged liver (i.e., CCl4). These results tend to support the hypothesis that kidney damage due to chronic Cd2+ poisoning may lead to an increased loss of the Cd2+ stored in the kidney."
197598,Williams 1992,DNA reactive and epigenetic carcinogens,Animal and human carcinogens exert their effects through diverse mechanisms which include DNA reaction and epigenetic effects. This review covers the basis for distinguishing between carcinogens that have either DNA reactivity or epigenetic activity as their primary effect.,DNA reactive and epigenetic carcinogens Abs: Animal and human carcinogens exert their effects through diverse mechanisms which include DNA reaction and epigenetic effects. This review covers the basis for distinguishing between carcinogens that have either DNA reactivity or epigenetic activity as their primary effect.
197071,Bagchi et al. 2002,"Comparative effects of TCDD, endrin, naphthalene and chromium (VI) on oxidative stress and tissue damage in the liver and brain tissues of mice","The mechanism of toxicity of structurally diverse environmental toxicants including heavy metals and polyhalogenated and polycyclic hydrocarbons may involve a common cascade of events which entails an oxidative stress and production of reactive oxygen species. We have determined the comparative effects of single 0.01, 0.10 and 0.50 LD(50) doses of 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD), endrin, naphthalene and sodium dichromate (chromium VI) on lipid peroxidation, DNA fragmentation and enhanced production of superoxide anion (cytochrome c reduction) in liver and brain tissues of C57BL/6NTac mice. The effects of a single acute oral 0.50 LD(50) dose of these xenobiotics on hepatic and brain lipid peroxidation were investigated at 0, 12, 24, 48, and 96 h after treatment, while the effects of 0.10 LD(50) and 0.01 LD(50) doses of these xenobiotics were at 0, 24, 48, 72, and 96 h after treatment. Dose- and time-dependent effects were observed with all four xenobiotics. At a 0.50 LD(50) dose of TCDD, endrin, naphthalene and chromium VI, maximum increases in cytochrome c reduction (superoxide anion production) of approximately 5.7-, 5.4-, 5.3- and 4.1-fold, respectively, were observed in hepatic tissues. TCDD showed an increasing effect through 96 h. Endrin and naphthalene demonstrated a maximum effect at 12-24 h, while chromium VI exhibited a maximum effect at 48 h. With respect to lipid peroxidation, at a 0.50 LD(50) dose both endrin and chromium VI induced the maximum effect at 48 h of treatment, while naphthalene demonstrated the maximum effect after 24 h of treatment. TCDD demonstrated a continued effect through 96 h of treatment. At a 0.50 LD(50) dose TCDD, endrin, naphthalene and chromium VI produced maximum increases in hepatic lipid peroxidation of approximately 3.5-, 3.1-, 3.7- and 3.3-fold in hepatic tissues, respectively. Similar results were obtained in hepatic and brain DNA fragmentation at 0.50 LD(50) doses. Lesser effects were observed with 0.10 and 0.01 LD(50) doses of these xenobiotics as compared to the 0.50 LD(50) dose. The results clearly demonstrate that these diverse xenobiotics induce dose- and time-dependent oxidative stress and tissue damage in the liver and brain tissues of mice.","Comparative effects of TCDD, endrin, naphthalene and chromium (VI) on oxidative stress and tissue damage in the liver and brain tissues of mice Abs: The mechanism of toxicity of structurally diverse environmental toxicants including heavy metals and polyhalogenated and polycyclic hydrocarbons may involve a common cascade of events which entails an oxidative stress and production of reactive oxygen species. We have determined the comparative effects of single 0.01, 0.10 and 0.50 LD(50) doses of 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD), endrin, naphthalene and sodium dichromate (chromium VI) on lipid peroxidation, DNA fragmentation and enhanced production of superoxide anion (cytochrome c reduction) in liver and brain tissues of C57BL/6NTac mice. The effects of a single acute oral 0.50 LD(50) dose of these xenobiotics on hepatic and brain lipid peroxidation were investigated at 0, 12, 24, 48, and 96 h after treatment, while the effects of 0.10 LD(50) and 0.01 LD(50) doses of these xenobiotics were at 0, 24, 48, 72, and 96 h after treatment. Dose- and time-dependent effects were observed with all four xenobiotics. At a 0.50 LD(50) dose of TCDD, endrin, naphthalene and chromium VI, maximum increases in cytochrome c reduction (superoxide anion production) of approximately 5.7-, 5.4-, 5.3- and 4.1-fold, respectively, were observed in hepatic tissues. TCDD showed an increasing effect through 96 h. Endrin and naphthalene demonstrated a maximum effect at 12-24 h, while chromium VI exhibited a maximum effect at 48 h. With respect to lipid peroxidation, at a 0.50 LD(50) dose both endrin and chromium VI induced the maximum effect at 48 h of treatment, while naphthalene demonstrated the maximum effect after 24 h of treatment. TCDD demonstrated a continued effect through 96 h of treatment. At a 0.50 LD(50) dose TCDD, endrin, naphthalene and chromium VI produced maximum increases in hepatic lipid peroxidation of approximately 3.5-, 3.1-, 3.7- and 3.3-fold in hepatic tissues, respectively. Similar results were obtained in hepatic and brain DNA fragmentation at 0.50 LD(50) doses. Lesser effects were observed with 0.10 and 0.01 LD(50) doses of these xenobiotics as compared to the 0.50 LD(50) dose. The results clearly demonstrate that these diverse xenobiotics induce dose- and time-dependent oxidative stress and tissue damage in the liver and brain tissues of mice."
195647,Liu et al. 2008,"Hexavalent chromium uptake and its effects on mineral uptake, antioxidant defence system and photosynthesis in Amaranthus viridis L","The effects of different concentrations (10(-6) M, 10(-5) M and 10(-4) M) of K2Cr2O7Cr(VI) on some minerals (Mn, Fe, Cu and Zn), lipid peroxidation, activities of antioxidant enzymes, photosynthetic function, and chlorophyll fluorescence characteristics were investigated in hydroponically grown Amaranthus viridis L. Results indicated that chromium was accumulated primarily in roots. In the roots and shoots, the Cr content increased with the increasing Cr(VI) concentrations, and induced decrease of Mn, Fe, Cu and Zn. Chromium Cr(VI) induced oxidation stress and lipid peroxidation in A. viridis L. shown by the increased concentration of NIDA. The increased activities of POD and SOD indicated that they could serve as important components of antioxidant defense mechanisms to minimize Cr induced oxidative injury. The net photosynthetic rate, transpiration rate, stomatal conductance and intercellular CO, concentration were reduced only by high Cr(VI) treatments (10(-5) M and 10(-4) M). The chlorophyll fluorescence parameters F-V/F-m, F-v'/F-m', Phi PSII and q(P), decreased in Cr(VI)-treated, but q(N) and NPQ showed an increase in Cr(VI) treated plants. (C) 2007 Elsevier Ltd. All rights reserved.","Hexavalent chromium uptake and its effects on mineral uptake, antioxidant defence system and photosynthesis in Amaranthus viridis L Abs: The effects of different concentrations (10(-6) M, 10(-5) M and 10(-4) M) of K2Cr2O7Cr(VI) on some minerals (Mn, Fe, Cu and Zn), lipid peroxidation, activities of antioxidant enzymes, photosynthetic function, and chlorophyll fluorescence characteristics were investigated in hydroponically grown Amaranthus viridis L. Results indicated that chromium was accumulated primarily in roots. In the roots and shoots, the Cr content increased with the increasing Cr(VI) concentrations, and induced decrease of Mn, Fe, Cu and Zn. Chromium Cr(VI) induced oxidation stress and lipid peroxidation in A. viridis L. shown by the increased concentration of NIDA. The increased activities of POD and SOD indicated that they could serve as important components of antioxidant defense mechanisms to minimize Cr induced oxidative injury. The net photosynthetic rate, transpiration rate, stomatal conductance and intercellular CO, concentration were reduced only by high Cr(VI) treatments (10(-5) M and 10(-4) M). The chlorophyll fluorescence parameters F-V/F-m, F-v'/F-m', Phi PSII and q(P), decreased in Cr(VI)-treated, but q(N) and NPQ showed an increase in Cr(VI) treated plants. (C) 2007 Elsevier Ltd. All rights reserved."
195439,Christofano et al. 1976,Toxicity of lead chromate pigments and tissue residues following 90 days feeding to beagle dogs,HEEP COPYRIGHT: BIOL ABS. ABSTRACT TOXICITY ANOREXIA DEHYDRATION LETHARGY EMACIATION HYPER IRRITABILITY DIS ORIENTATION ATAXIA CONVULSIONS METABOLISM,Toxicity of lead chromate pigments and tissue residues following 90 days feeding to beagle dogs Abs: HEEP COPYRIGHT: BIOL ABS. ABSTRACT TOXICITY ANOREXIA DEHYDRATION LETHARGY EMACIATION HYPER IRRITABILITY DIS ORIENTATION ATAXIA CONVULSIONS METABOLISM
194833,Elia et al. 1994,Rapid DNA degradation in primary rat hepatocytes treated with diverse cytotoxic chemicals: Analysis by pulsed field gel electrophoresis and implications for alkaline elution assays,"The use of genetic toxicology tests for hazard identification is complicated by the fact that some in vitro tests using cultured mammalian cells are subject to potential artifacts that can make it difficult to distinguish between direct, chemically-induced genotoxicity, and DNA damage that occurs secondary to chemically-induced cytotoxicity (e.g., mediated by endogenous nucleases). Recently, we demonstrated that cytotoxicity-induced DNA double strand breaks (dsb) can produce artifacts in the in vitro alkaline elution/rat hepatocyte assay [Elia et al., 1993]. To explore this further, we used pulsed field gel/DNA dsb assays to characterize the relationship between chemically-induced cytotoxicity and the degradation of genomic DNA to high molecular weight fragments. Two sets of compounds were tested: 17 cytotoxic agents judged to be neither genotoxic nor carcinogenic, and 10 known genotoxic carcinogens. We found a close correlation between chemically-induced cytotoxicity and the rapid degradation of DNA to high molecular weight, double-stranded fragments. In contrast, the classic genotoxic chemicals tested generally did not trigger DNA dsb fragmentation at doses that were genotoxic but not immediately cytotoxic. These data indicate that pulsed field gel/DNA dsb assays can be used with in vitro genetic toxicology assays to help distinguish between genotoxic and cytotoxic mechanisms of DNA damage.","Rapid DNA degradation in primary rat hepatocytes treated with diverse cytotoxic chemicals: Analysis by pulsed field gel electrophoresis and implications for alkaline elution assays Abs: The use of genetic toxicology tests for hazard identification is complicated by the fact that some in vitro tests using cultured mammalian cells are subject to potential artifacts that can make it difficult to distinguish between direct, chemically-induced genotoxicity, and DNA damage that occurs secondary to chemically-induced cytotoxicity (e.g., mediated by endogenous nucleases). Recently, we demonstrated that cytotoxicity-induced DNA double strand breaks (dsb) can produce artifacts in the in vitro alkaline elution/rat hepatocyte assay [Elia et al., 1993]. To explore this further, we used pulsed field gel/DNA dsb assays to characterize the relationship between chemically-induced cytotoxicity and the degradation of genomic DNA to high molecular weight fragments. Two sets of compounds were tested: 17 cytotoxic agents judged to be neither genotoxic nor carcinogenic, and 10 known genotoxic carcinogens. We found a close correlation between chemically-induced cytotoxicity and the rapid degradation of DNA to high molecular weight, double-stranded fragments. In contrast, the classic genotoxic chemicals tested generally did not trigger DNA dsb fragmentation at doses that were genotoxic but not immediately cytotoxic. These data indicate that pulsed field gel/DNA dsb assays can be used with in vitro genetic toxicology assays to help distinguish between genotoxic and cytotoxic mechanisms of DNA damage."
194809,Kauppinen et al. 2003,Exposure to chemical carcinogens and risk of cancer among Finnish laboratory workers,"BACKGROUND: Laboratory workers have long been suspected of having increased risks of cancer due to their occupation. We evaluated occupational exposure and cancer incidence among Finnish laboratory workers. MATERIALS AND METHODS: The cohort was comprised of 4,722 laboratory workers reported to the Finnish Register of Workers Exposed to Carcinogens in 1979-1988. The standardized incidence ratios (SIR) for cancers and their 95% confidence intervals (CI) were calculated based on data of the Finnish Cancer Registry. RESULTS: The most common carcinogens, to which these workers were potentially exposed, were chromium (VI), carbon tetrachloride, cadmium, benzene, and chloroform. From this cohort, 174 persons were recorded with primary tumors in 1980-1999. The SIR for cancer of all sites combined was 0.99 (CI 0.85-1.14). None of the cancer-specific SIRs were significantly elevated. Slight excesses were found, e.g., for non-Hodgkin's lymphoma (seven observed, 4.8 expected) and leukemia (four observed, three expected). CONCLUSIONS: This study did not suggest any major cancer risks among Finnish laboratory workers but the follow-up time of the cohort was too short (on an average 15.7 years) to reveal possible cancer risks requiring a longer induction period. Copyright 2003 Wiley-Liss, Inc.","Exposure to chemical carcinogens and risk of cancer among Finnish laboratory workers Abs: BACKGROUND: Laboratory workers have long been suspected of having increased risks of cancer due to their occupation. We evaluated occupational exposure and cancer incidence among Finnish laboratory workers. MATERIALS AND METHODS: The cohort was comprised of 4,722 laboratory workers reported to the Finnish Register of Workers Exposed to Carcinogens in 1979-1988. The standardized incidence ratios (SIR) for cancers and their 95% confidence intervals (CI) were calculated based on data of the Finnish Cancer Registry. RESULTS: The most common carcinogens, to which these workers were potentially exposed, were chromium (VI), carbon tetrachloride, cadmium, benzene, and chloroform. From this cohort, 174 persons were recorded with primary tumors in 1980-1999. The SIR for cancer of all sites combined was 0.99 (CI 0.85-1.14). None of the cancer-specific SIRs were significantly elevated. Slight excesses were found, e.g., for non-Hodgkin's lymphoma (seven observed, 4.8 expected) and leukemia (four observed, three expected). CONCLUSIONS: This study did not suggest any major cancer risks among Finnish laboratory workers but the follow-up time of the cohort was too short (on an average 15.7 years) to reveal possible cancer risks requiring a longer induction period. Copyright 2003 Wiley-Liss, Inc."
194631,Watanabe et al. 1998,"Comparisons on chemically-induced mutation among four bacterial strains, Salmonella typhimurium TA102 and TA2638, and Escherichia coli WP2/pKM101 and WP2 uvrA/pKM101: Collaborative study II","A collaborative study of chemically-induced mutation was performed using the four bacterial strains Salmonella typhimurium TA102 and TA2638, and Escherichia coli WP2/pKM101 and WP2 uvrA/pKM101, used in the previous successive studies in order to compare the specific spectrum of response to chemicals among the four strains and to determine the usefulness (sensitivity) of each strain. Twenty-two laboratories participated in this study. Following the previous study, 28 compounds were selected consisting of oxidative agents or crosslinking agents. These compounds were tested for mutagenicity using the plate incorporation method with or without metabolic activation. The tests were performed in two laboratories per chemical. The number of chemicals which showed positive results were 18, 17, 16 and 14 with WP2 uvrA/pKM101, TA2638, TA102 and WP2/pKM101, respectively. In all four strains 19/28 chemicals (68%) were either positive or negative while the remaining 9 chemicals showed a heterogeneous response. With TA102 and TA2638 89% (25/28) of the test chemicals showed the same response, while 75–79% (21–22/28) showed the same response in these two S. typhimurium strains and in WP2 uvrA/pKM101. In conclusion, WP2/pKM101 strain showed the least sensitivity to the chemicals used. Among the other three strains, WP2 uvrA/pKM101 was the most sensitive strain, although the difference in the number of chemicals which showed positive results was minor. Concerning the spectrum of response to chemicals, it is apparent that TA102 and TA2638 have almost the same sensitivity, but some chemicals induce different responses between the two S. typhimurium strains and WP2 uvrA/pKM101.","Comparisons on chemically-induced mutation among four bacterial strains, Salmonella typhimurium TA102 and TA2638, and Escherichia coli WP2/pKM101 and WP2 uvrA/pKM101: Collaborative study II Abs: A collaborative study of chemically-induced mutation was performed using the four bacterial strains Salmonella typhimurium TA102 and TA2638, and Escherichia coli WP2/pKM101 and WP2 uvrA/pKM101, used in the previous successive studies in order to compare the specific spectrum of response to chemicals among the four strains and to determine the usefulness (sensitivity) of each strain. Twenty-two laboratories participated in this study. Following the previous study, 28 compounds were selected consisting of oxidative agents or crosslinking agents. These compounds were tested for mutagenicity using the plate incorporation method with or without metabolic activation. The tests were performed in two laboratories per chemical. The number of chemicals which showed positive results were 18, 17, 16 and 14 with WP2 uvrA/pKM101, TA2638, TA102 and WP2/pKM101, respectively. In all four strains 19/28 chemicals (68%) were either positive or negative while the remaining 9 chemicals showed a heterogeneous response. With TA102 and TA2638 89% (25/28) of the test chemicals showed the same response, while 75–79% (21–22/28) showed the same response in these two S. typhimurium strains and in WP2 uvrA/pKM101. In conclusion, WP2/pKM101 strain showed the least sensitivity to the chemicals used. Among the other three strains, WP2 uvrA/pKM101 was the most sensitive strain, although the difference in the number of chemicals which showed positive results was minor. Concerning the spectrum of response to chemicals, it is apparent that TA102 and TA2638 have almost the same sensitivity, but some chemicals induce different responses between the two S. typhimurium strains and WP2 uvrA/pKM101."
194252,Paustenbach et al. 1996,Observation of steady state in blood and urine following human ingestion of hexavalent chromium in drinking water,"The uptake and elimination of Cr(VI) in a male volunteer who ingested 2 L/d of water containing 2 mg/L for 17 consecutive days was measured. Total chromium was measured in urine, plasma, and red blood cells (RBCs) for 4 d prior to and 2 wk after dosing (34 d total). The estimated bioavailability (2%) and the plasma elimination half-life (36 h) were consistent with our previous studies of Cr(VI) ingestion in humans. Steady-state chromium concentrations in urine and blood were achieved after 7 d of Cr(VI) ingestion. Both plasma and red blood cell (RBC) chromium concentrations returned rapidly to background levels within a few days after cessation of dosing. Since the concentration of chromium in the RBC should not decrease quickly if the chromium had entered the RBC as Cr(VI), these data support our prior work suggesting that concentrations of 10 mg Cr(VI)/L or less in drinking water of exposed humans appears to be completely reduced to Cr(III) prior to systemic distribution. Clinical chemistry data indicate that no toxicity occurred.","Observation of steady state in blood and urine following human ingestion of hexavalent chromium in drinking water Abs: The uptake and elimination of Cr(VI) in a male volunteer who ingested 2 L/d of water containing 2 mg/L for 17 consecutive days was measured. Total chromium was measured in urine, plasma, and red blood cells (RBCs) for 4 d prior to and 2 wk after dosing (34 d total). The estimated bioavailability (2%) and the plasma elimination half-life (36 h) were consistent with our previous studies of Cr(VI) ingestion in humans. Steady-state chromium concentrations in urine and blood were achieved after 7 d of Cr(VI) ingestion. Both plasma and red blood cell (RBC) chromium concentrations returned rapidly to background levels within a few days after cessation of dosing. Since the concentration of chromium in the RBC should not decrease quickly if the chromium had entered the RBC as Cr(VI), these data support our prior work suggesting that concentrations of 10 mg Cr(VI)/L or less in drinking water of exposed humans appears to be completely reduced to Cr(III) prior to systemic distribution. Clinical chemistry data indicate that no toxicity occurred."
194249,Kuykendall et al. 1996,Measurement of DNA-protein cross-links in human leukocytes following acute ingestion of chromium in drinking water,"Increased DNA-protein cross-linking (DPX) in circulating leukocytes has been proposed as a potential biomarker for exposure and genotoxic damage caused by inhalation of certain reactive chemicals, such as hexavalent chromium [Cr(VI)]. This study was designed to determine whether ingestion of a single dose of potassium dichromate alone [Cr(VI)] or potassium dichromate fully reduced to Cr(III) with orange juice (prior to ingestion) causes an increase in DPX of circulating leukocytes in humans. Four adult male volunteers ingested a bolus dose of 5000 micro chromium in a 0.51 volume of water (10 p.p.m.), and blood samples were collected at 0, 60, 120, 180 and 240 min afterwards for analysis of DPX formation in circulating leukocytes. Results were compared to each person's own background concentration of DPX in leukocytes. Blood and urine samples were also collected for up to 2 weeks following the dose to examine the pattern of uptake and excretion of chromium. The results showed that there was no significant change in DPX observed following either Cr(VI) or Cr(III) ingestion, even though blood and urine chromium measurements indicated systemic uptake of a substantial fraction of the ingested chromium. Since Cr(III) does not possess DPX-inducing properties while Cr(VI) does, these results suggest that the Cr(VI) was reduced to Cr(III) intragastrically prior to absorption or that the amount of Cr(VI) absorbed into the blood was insufficient to produce DPX. These results are consistent with prior research that indicated that DPX would not occur following exposure to Cr(VI) except at very high doses.","Measurement of DNA-protein cross-links in human leukocytes following acute ingestion of chromium in drinking water Abs: Increased DNA-protein cross-linking (DPX) in circulating leukocytes has been proposed as a potential biomarker for exposure and genotoxic damage caused by inhalation of certain reactive chemicals, such as hexavalent chromium [Cr(VI)]. This study was designed to determine whether ingestion of a single dose of potassium dichromate alone [Cr(VI)] or potassium dichromate fully reduced to Cr(III) with orange juice (prior to ingestion) causes an increase in DPX of circulating leukocytes in humans. Four adult male volunteers ingested a bolus dose of 5000 micro chromium in a 0.51 volume of water (10 p.p.m.), and blood samples were collected at 0, 60, 120, 180 and 240 min afterwards for analysis of DPX formation in circulating leukocytes. Results were compared to each person's own background concentration of DPX in leukocytes. Blood and urine samples were also collected for up to 2 weeks following the dose to examine the pattern of uptake and excretion of chromium. The results showed that there was no significant change in DPX observed following either Cr(VI) or Cr(III) ingestion, even though blood and urine chromium measurements indicated systemic uptake of a substantial fraction of the ingested chromium. Since Cr(III) does not possess DPX-inducing properties while Cr(VI) does, these results suggest that the Cr(VI) was reduced to Cr(III) intragastrically prior to absorption or that the amount of Cr(VI) absorbed into the blood was insufficient to produce DPX. These results are consistent with prior research that indicated that DPX would not occur following exposure to Cr(VI) except at very high doses."
192336,Malsch et al. 1994,Estimation of a chromium inhalation reference concentration using the benchmark dose method: a case study,"The benchmark dose (BD) method has been proposed as an alternative to the NOAEL/UF method for setting reference levels. The BD is the 95% lower confidence limit on a dose corresponding to a 10% increase (or relative change) in an adverse effect. A case study exploring the suitability of the current Cr(III) and Cr(VI) inhalation toxicity data bases to the BD approach is presented. Because chromic acid mists, typical of many occupational Cr(VI) exposures, present a toxicological profile different from that of Cr(VI) particulates, representative of environmental exposures, Cr(VI) particulate data were evaluated separately from Cr(VI) acidic mist data. The current Cr(III) and Cr(VI) acidic mist data bases proved inadequate for BD analysis due to data and/or study quality limitations. Benchmark reference concentrations (RfCs) for particulate Cr(VI) ranging from 0.34 microgram/m3 (for lactate dehydrogenase (LDH) in bronchoalveolar lavage fluid (BALF)) to 1.4 micrograms/m3 (for increased lung weights) are derived from data taken from U. Glaser et al. (Arch. Toxicol. 57, 250-256, 1985) and U. Glaser et al. (Environmental Hygiene II, Springer-Verlag, Berlin/New York, 1990). A Cr(VI) particulate RfC of 0.34 microgram/m3 based upon LDH in BALF as the critical effect is proposed. This value may be viewed as conservative since it represents the 95% lower confidence limit on the dose associated with a 10% increase in response for a sensitive endpoint and has appropriate dosimetric adjustments and uncertainty factors incorporated.","Estimation of a chromium inhalation reference concentration using the benchmark dose method: a case study Abs: The benchmark dose (BD) method has been proposed as an alternative to the NOAEL/UF method for setting reference levels. The BD is the 95% lower confidence limit on a dose corresponding to a 10% increase (or relative change) in an adverse effect. A case study exploring the suitability of the current Cr(III) and Cr(VI) inhalation toxicity data bases to the BD approach is presented. Because chromic acid mists, typical of many occupational Cr(VI) exposures, present a toxicological profile different from that of Cr(VI) particulates, representative of environmental exposures, Cr(VI) particulate data were evaluated separately from Cr(VI) acidic mist data. The current Cr(III) and Cr(VI) acidic mist data bases proved inadequate for BD analysis due to data and/or study quality limitations. Benchmark reference concentrations (RfCs) for particulate Cr(VI) ranging from 0.34 microgram/m3 (for lactate dehydrogenase (LDH) in bronchoalveolar lavage fluid (BALF)) to 1.4 micrograms/m3 (for increased lung weights) are derived from data taken from U. Glaser et al. (Arch. Toxicol. 57, 250-256, 1985) and U. Glaser et al. (Environmental Hygiene II, Springer-Verlag, Berlin/New York, 1990). A Cr(VI) particulate RfC of 0.34 microgram/m3 based upon LDH in BALF as the critical effect is proposed. This value may be viewed as conservative since it represents the 95% lower confidence limit on the dose associated with a 10% increase in response for a sensitive endpoint and has appropriate dosimetric adjustments and uncertainty factors incorporated."
192335,U.S. EPA 1998,Toxicological review of hexavalent chromium,The Integrated Risk Information System (IRIS) is a database of U.S. Environmental Protection Agency consensus positions on the health effects that may result from chronic exposure to various chemicals found in the environment. The Purpose of this Toxicological Review is to provide scientific support and rationale for the hazard identification and dose-response information in IRIS pertinent to Hexavalent Chromium.,Toxicological review of hexavalent chromium Abs: The Integrated Risk Information System (IRIS) is a database of U.S. Environmental Protection Agency consensus positions on the health effects that may result from chronic exposure to various chemicals found in the environment. The Purpose of this Toxicological Review is to provide scientific support and rationale for the hazard identification and dose-response information in IRIS pertinent to Hexavalent Chromium.
188395,Güerci et al. 2000,Aneugenic effects of some metal compounds assessed by chromosome counting in MRC-5 human cells,"Development of a comprehensive test battery is necesary for the evaluation and detection of aneugenic chemicals. The chromosome couting method was used in the present study. The aneugenic ability of cadmium choride (1.0, 2.0 and 4.0x10(-3) mM), cadmium sulfate (3. 3, 6.7x10(-5) and 1.3x10(-4) mM), potassium dichromate (2.5, 5. 0x10(-4) and 1.0x10(-3) mM) and cacodilic acid (1.25, 2.5 and 5. 0x10(-2) mM) were analysed using MRC-5 cells which have a modal diploid number of 2 n=46 with a spontaneous aneuploid or polyploid cells not higher than 13% and 8%, respectively.All compounds induced significant increments of aneuploid cells in relation to negative controls. The frequency of aneuploid cells increased in all treatments with cadmium chloride. Cadmium sulfate induced significant increments of aneuploid cells with the two higher doses. All the doses of potassium dichromate increased the frequency of aneuploid cells although to a lesser degree than the other compounds. In these cases, differences were in the borderline of statistical significance (p<0.05). Moreover, a low number of cells could be analysed in treatments with the highest dose due to the decrease in the mitotic index.Results obtained are coincident with previous reports using the same methodology in the sense that induced aneuploidy was mainly evidenced by the increase of hypodiploid but not hyperdiploid cells. In addition, anaphase-telophase analysis of the effects of the same doses of these metal compounds in CHO cells showed significant increments of lagging chromosomes and increased frequencies of kinetochore positive micronuclei in MRC-5 cells. These findings could be considered as an indication that the main cause of unequal chromosome separation is the failure of kinetochores to attach the spindle apparatus either by alteration of its protein components or by the altered chromatid separation in anaphase.","Aneugenic effects of some metal compounds assessed by chromosome counting in MRC-5 human cells Abs: Development of a comprehensive test battery is necesary for the evaluation and detection of aneugenic chemicals. The chromosome couting method was used in the present study. The aneugenic ability of cadmium choride (1.0, 2.0 and 4.0x10(-3) mM), cadmium sulfate (3. 3, 6.7x10(-5) and 1.3x10(-4) mM), potassium dichromate (2.5, 5. 0x10(-4) and 1.0x10(-3) mM) and cacodilic acid (1.25, 2.5 and 5. 0x10(-2) mM) were analysed using MRC-5 cells which have a modal diploid number of 2 n=46 with a spontaneous aneuploid or polyploid cells not higher than 13% and 8%, respectively.All compounds induced significant increments of aneuploid cells in relation to negative controls. The frequency of aneuploid cells increased in all treatments with cadmium chloride. Cadmium sulfate induced significant increments of aneuploid cells with the two higher doses. All the doses of potassium dichromate increased the frequency of aneuploid cells although to a lesser degree than the other compounds. In these cases, differences were in the borderline of statistical significance (p<0.05). Moreover, a low number of cells could be analysed in treatments with the highest dose due to the decrease in the mitotic index.Results obtained are coincident with previous reports using the same methodology in the sense that induced aneuploidy was mainly evidenced by the increase of hypodiploid but not hyperdiploid cells. In addition, anaphase-telophase analysis of the effects of the same doses of these metal compounds in CHO cells showed significant increments of lagging chromosomes and increased frequencies of kinetochore positive micronuclei in MRC-5 cells. These findings could be considered as an indication that the main cause of unequal chromosome separation is the failure of kinetochores to attach the spindle apparatus either by alteration of its protein components or by the altered chromatid separation in anaphase."
188336,Min et al. 1987,Protective role of renal metallothionein against Cd nephropathy in rats,"Rats were treated with four types of Cd compound: CdCl2, Cd bound to Cys (Cd-Cys), Cd bound to a peptide corresponding to a partial sequence of metallothionein (Cd-peptide), and Cd bound to metallothionein (Cd-MT). This treatment caused no nephropathy. Subsequently, toxic doses of Cd compounds were administered to these pretreated rats and their effects on renal function were examined. When 1.4 mg Cd/kg as Cd-Cys was administered, marked increases in urinary protein, glucose, and amino acid were observed. However, when the animals were pretreated with 1 mg Cd/kg/day as CdCl2 for 3 days, and 1.4 mg Cd/kg as Cd-Cys was administered 24 hr later, no renal damage was observed. Such a protective effect against the nephrotoxic action of Cd-Cys was also shown by pretreatment with Cd-Cys, Cd-peptide, or Cd-MT. Furthermore such a phenomenon was also observed when the nephropathy was caused by Cd-peptide or Cd-MT. The efficacy of pretreatment depended on the time before subsequent administration of Cd and the dose used for pretreatment. Incorporation of Cd into the liver and the kidney was not altered by the pretreatment. No matter in which form the nephrotoxic dose of Cd was administered, the incorporated Cd was distributed between particulates and cytosol; 3 hr after administration, cytosolic Cd was present in almost equal amounts in the high-molecular-weight and the MT fractions in the nonpretreated rats. However, after pretreatment, more of the Cd subsequently administered was found in the MT fraction. These results suggest that MT participates in the detoxication mechanism against Cd in the kidney, as it does in the liver.","Protective role of renal metallothionein against Cd nephropathy in rats Abs: Rats were treated with four types of Cd compound: CdCl2, Cd bound to Cys (Cd-Cys), Cd bound to a peptide corresponding to a partial sequence of metallothionein (Cd-peptide), and Cd bound to metallothionein (Cd-MT). This treatment caused no nephropathy. Subsequently, toxic doses of Cd compounds were administered to these pretreated rats and their effects on renal function were examined. When 1.4 mg Cd/kg as Cd-Cys was administered, marked increases in urinary protein, glucose, and amino acid were observed. However, when the animals were pretreated with 1 mg Cd/kg/day as CdCl2 for 3 days, and 1.4 mg Cd/kg as Cd-Cys was administered 24 hr later, no renal damage was observed. Such a protective effect against the nephrotoxic action of Cd-Cys was also shown by pretreatment with Cd-Cys, Cd-peptide, or Cd-MT. Furthermore such a phenomenon was also observed when the nephropathy was caused by Cd-peptide or Cd-MT. The efficacy of pretreatment depended on the time before subsequent administration of Cd and the dose used for pretreatment. Incorporation of Cd into the liver and the kidney was not altered by the pretreatment. No matter in which form the nephrotoxic dose of Cd was administered, the incorporated Cd was distributed between particulates and cytosol; 3 hr after administration, cytosolic Cd was present in almost equal amounts in the high-molecular-weight and the MT fractions in the nonpretreated rats. However, after pretreatment, more of the Cd subsequently administered was found in the MT fraction. These results suggest that MT participates in the detoxication mechanism against Cd in the kidney, as it does in the liver."
188266,Depault et al. 2006,Genotoxic effects of chromium(VI) and cadmium(II) in human blood lymphocytes using the electron microscopy in situ end-labeling (EM-ISEL) assay,"Evaluation of genotoxic effects of potassium chromate (K2CrO4) and cadmium chloride (CdCl2) was carried out in human blood lymphocytes in vitro as measured by the electron microscopy in situ end-labeling (EM-ISEL). EM-ISEL was used to assess DNA single-strand breaks (SSBs) expressed as number of immunogold particles per microm2 of chromatin at both chromosomal and nuclear DNA levels. Human lymphocytes were cultured in supplemented RPMI medium for 72 h including treatment for 2 h with K2CrO4 (0-150 microM), CdCl2 (0-150 microM) or methyl methanesulfonate (500 microM) as a positive control. Quantification of SSBs by EM-ISEL showed that both compounds are genotoxic agents at non-cytotoxic concentrations. This study brings new information on the utility of EM-ISEL for the evaluation of genotoxicity and confirms the genotoxic effects induced by chromium and cadmium.","Genotoxic effects of chromium(VI) and cadmium(II) in human blood lymphocytes using the electron microscopy in situ end-labeling (EM-ISEL) assay Abs: Evaluation of genotoxic effects of potassium chromate (K2CrO4) and cadmium chloride (CdCl2) was carried out in human blood lymphocytes in vitro as measured by the electron microscopy in situ end-labeling (EM-ISEL). EM-ISEL was used to assess DNA single-strand breaks (SSBs) expressed as number of immunogold particles per microm2 of chromatin at both chromosomal and nuclear DNA levels. Human lymphocytes were cultured in supplemented RPMI medium for 72 h including treatment for 2 h with K2CrO4 (0-150 microM), CdCl2 (0-150 microM) or methyl methanesulfonate (500 microM) as a positive control. Quantification of SSBs by EM-ISEL showed that both compounds are genotoxic agents at non-cytotoxic concentrations. This study brings new information on the utility of EM-ISEL for the evaluation of genotoxicity and confirms the genotoxic effects induced by chromium and cadmium."
187145,Beyersmann 2002,Effects of carcinogenic metals on gene expression,"Six metals and/or their compounds have been recognized as carcinogens: arsenic, beryllium, cadmium, chromium, cobalt and nickel. With the exception of arsenic, the main rote of exposure is inhalation and the main target organ is the lung. Arsenic is exceptional because it also produces tumors of skin and lung after oral uptake. With the exception of hexavalent chromium, carcinogenic metals are weak mutagens, if at all, and their mechanisms of carcinogenicity are still far from clear. A general feature of arsenic, cadmium, cobalt and nickel is their property to enhance the mutagenicity and carcinogenicity of directly acting genotoxic agents. These properties can be interpreted in terms of the ability of these metals to inhibit the repair of damaged DNA. However, because carcinogenic metals cause tumor development in experimental animals even under exclusion of further carcinogens, other mechanisms have to be envisaged, too. Evidence will be discussed that carcinogenic metal compounds alter patterns of gene expression leading to stimulated cell proliferation, either by activation of early genes (proto-oncogenes) or by interference with genes downregulating cell growth. Special reference will be devoted to the effects of cadmium and arsenic on gene expression, which have been studied extensively. Possible implications for occupational safety and health will be discussed.","Effects of carcinogenic metals on gene expression Abs: Six metals and/or their compounds have been recognized as carcinogens: arsenic, beryllium, cadmium, chromium, cobalt and nickel. With the exception of arsenic, the main rote of exposure is inhalation and the main target organ is the lung. Arsenic is exceptional because it also produces tumors of skin and lung after oral uptake. With the exception of hexavalent chromium, carcinogenic metals are weak mutagens, if at all, and their mechanisms of carcinogenicity are still far from clear. A general feature of arsenic, cadmium, cobalt and nickel is their property to enhance the mutagenicity and carcinogenicity of directly acting genotoxic agents. These properties can be interpreted in terms of the ability of these metals to inhibit the repair of damaged DNA. However, because carcinogenic metals cause tumor development in experimental animals even under exclusion of further carcinogens, other mechanisms have to be envisaged, too. Evidence will be discussed that carcinogenic metal compounds alter patterns of gene expression leading to stimulated cell proliferation, either by activation of early genes (proto-oncogenes) or by interference with genes downregulating cell growth. Special reference will be devoted to the effects of cadmium and arsenic on gene expression, which have been studied extensively. Possible implications for occupational safety and health will be discussed."
184399,Bagchi et al. 2000,"Cadmium- and chromium-induced oxidative stress, DNA damage, and apoptotic cell death in cultured human chronic myelogenous leukemic K562 cells, promyelocytic leukemic HL-60 cells, and normal human peripheral blood mononuclear cells","Sodium dichromate [Cr(VI)] and cadmium chloride [Cd(II)] are both cytotoxic and mutagenic. This study examined the toxic and apoptotic potentials of these two cations on three cell types in vitro, namely, human chronic myelogenous leukemic (CML) K562 cells, promyelocytic leukemic HL-60 cells, and normal human peripheral blood mononuclear cells. The cells were incubated with 0-100 microM concentrations of the two cations for 0, 24, or 48 hours at 37 degrees C. Both Cr(VI) and Cd(II) induced changes in intracellular oxidized states of cells, which were detected using laser scanning confocal microscopy. Cell cycle modulation and apoptosis of the K562 cells by Cr(VI) and Cd(II) were determined by flow cytometry. Significant decreases in the G2/M phase were observed in the Cr(VI) and Cd(II) treated CML cells compared with untreated cells. At 12.5 microM, Cr(VI) induced greater apoptosis in K562 cells as compared with Cd(II). In the K562 cells, 2.2- and 3.0-fold increases in DNA fragmentation were observed following incubation with 12.5 and 25 microM Cr(VI), respectively, and 1.2- and 1.7-fold increases in DNA fragmentation were observed with Cd(II). Furthermore, approximately 2.7- and 4.9-fold increases in cytochrome c reduction were observed following incubation with 12.5 and 25 microM Cr(VI), respectively, and 1.6- and 3.3-fold increases in cytochrome c reduction were observed with Cd(II), demonstrating enhanced production of superoxide anion. Approximately 3.1 to 6-fold increases in hydroxyl radical production were observed following incubation of the K562 cells with these cations at 12.5 and 25 microM concentrations. These results in K562 cells were compared with promyelocytic leukemic HL-60 cells and normal human peripheral blood mononuclear cells. More pronounced effects were observed on K562 and HL-60 cells, and much lesser effects were observed on normal human peripheral blood mononuclear cells. The results demonstrate that both cations are toxic, producing oxidative tissue damage and apoptosis. Furthermore, more drastic effects were observed on K562 and HL-60 cells as compared with normal human peripheral blood mononuclear cells.","Cadmium- and chromium-induced oxidative stress, DNA damage, and apoptotic cell death in cultured human chronic myelogenous leukemic K562 cells, promyelocytic leukemic HL-60 cells, and normal human peripheral blood mononuclear cells Abs: Sodium dichromate [Cr(VI)] and cadmium chloride [Cd(II)] are both cytotoxic and mutagenic. This study examined the toxic and apoptotic potentials of these two cations on three cell types in vitro, namely, human chronic myelogenous leukemic (CML) K562 cells, promyelocytic leukemic HL-60 cells, and normal human peripheral blood mononuclear cells. The cells were incubated with 0-100 microM concentrations of the two cations for 0, 24, or 48 hours at 37 degrees C. Both Cr(VI) and Cd(II) induced changes in intracellular oxidized states of cells, which were detected using laser scanning confocal microscopy. Cell cycle modulation and apoptosis of the K562 cells by Cr(VI) and Cd(II) were determined by flow cytometry. Significant decreases in the G2/M phase were observed in the Cr(VI) and Cd(II) treated CML cells compared with untreated cells. At 12.5 microM, Cr(VI) induced greater apoptosis in K562 cells as compared with Cd(II). In the K562 cells, 2.2- and 3.0-fold increases in DNA fragmentation were observed following incubation with 12.5 and 25 microM Cr(VI), respectively, and 1.2- and 1.7-fold increases in DNA fragmentation were observed with Cd(II). Furthermore, approximately 2.7- and 4.9-fold increases in cytochrome c reduction were observed following incubation with 12.5 and 25 microM Cr(VI), respectively, and 1.6- and 3.3-fold increases in cytochrome c reduction were observed with Cd(II), demonstrating enhanced production of superoxide anion. Approximately 3.1 to 6-fold increases in hydroxyl radical production were observed following incubation of the K562 cells with these cations at 12.5 and 25 microM concentrations. These results in K562 cells were compared with promyelocytic leukemic HL-60 cells and normal human peripheral blood mononuclear cells. More pronounced effects were observed on K562 and HL-60 cells, and much lesser effects were observed on normal human peripheral blood mononuclear cells. The results demonstrate that both cations are toxic, producing oxidative tissue damage and apoptosis. Furthermore, more drastic effects were observed on K562 and HL-60 cells as compared with normal human peripheral blood mononuclear cells."
184391,Bagchi et al. 1997,Induction of oxidative stress by chronic administration of sodium dichromate [chromium VI] and cadmium chloride [cadmium II] to rats,"Recent studies have demonstrated that both chromium (VI) and cadmium (II) induce an oxidative stress, as determined by increased hepatic lipid peroxidation, hepatic glutathione depletion, hepatic nuclear DNA damage, and excretion of urinary lipid metabolites. However, whether chronic exposure to low levels of Cr(VI) and Cd(II) will produce an oxidative stress is not shown. The effects of oral, low (0.05 LD50) doses of sodium dichromate [Cr(VI); 2.5 mg/kg/d] and cadmium chloride [Cd(II); 4.4 mg/kg/d] in water on hepatic and brain mitochondrial and microsomal lipid peroxidation, excretion of urinary lipid metabolites including malondialdehyde, formaldehyde, acetaldehyde and acetone, and hepatic nuclear DNA-single strand breaks (SSB) were examined in female Sprague-Dawley rats over a period of 120 d. The animals were treated daily using an intragastric feeding needle. Maximum increases in hepatic and brain lipid peroxidation were observed between 60 and 75 d of treatment with both cations. Following Cr(VI) administration for 75 d, maximum increases in the urinary excretion of malondialdehyde, formaldehyde, acetaldehyde, and acetone were 2.1-, 1.8-, 2.1-, and 2.1-fold, respectively, while under the same conditions involving Cd(II) administration approximately 1.8-, 1.5-, 1.9-, and 1.5-fold increases were observed, respectively, as compared to control values. Following administration of Cr(VI) and Cd(II) for 75 d, approximately 2.4- and 3.8-fold increases in hepatic nuclear DNA-SSB were observed, respectively, while approximately 1.3- and 2.0-fold increases in brain nuclear DNA-SSB were observed, respectively. The results clearly indicate that low dose chronic administration of sodium dichromate and cadmium chloride induces an oxidative stress resulting in tissue damaging effects that may contribute to the toxicity and carcinogenicity of these two cations.","Induction of oxidative stress by chronic administration of sodium dichromate [chromium VI] and cadmium chloride [cadmium II] to rats Abs: Recent studies have demonstrated that both chromium (VI) and cadmium (II) induce an oxidative stress, as determined by increased hepatic lipid peroxidation, hepatic glutathione depletion, hepatic nuclear DNA damage, and excretion of urinary lipid metabolites. However, whether chronic exposure to low levels of Cr(VI) and Cd(II) will produce an oxidative stress is not shown. The effects of oral, low (0.05 LD50) doses of sodium dichromate [Cr(VI); 2.5 mg/kg/d] and cadmium chloride [Cd(II); 4.4 mg/kg/d] in water on hepatic and brain mitochondrial and microsomal lipid peroxidation, excretion of urinary lipid metabolites including malondialdehyde, formaldehyde, acetaldehyde and acetone, and hepatic nuclear DNA-single strand breaks (SSB) were examined in female Sprague-Dawley rats over a period of 120 d. The animals were treated daily using an intragastric feeding needle. Maximum increases in hepatic and brain lipid peroxidation were observed between 60 and 75 d of treatment with both cations. Following Cr(VI) administration for 75 d, maximum increases in the urinary excretion of malondialdehyde, formaldehyde, acetaldehyde, and acetone were 2.1-, 1.8-, 2.1-, and 2.1-fold, respectively, while under the same conditions involving Cd(II) administration approximately 1.8-, 1.5-, 1.9-, and 1.5-fold increases were observed, respectively, as compared to control values. Following administration of Cr(VI) and Cd(II) for 75 d, approximately 2.4- and 3.8-fold increases in hepatic nuclear DNA-SSB were observed, respectively, while approximately 1.3- and 2.0-fold increases in brain nuclear DNA-SSB were observed, respectively. The results clearly indicate that low dose chronic administration of sodium dichromate and cadmium chloride induces an oxidative stress resulting in tissue damaging effects that may contribute to the toxicity and carcinogenicity of these two cations."
180443,Yuan et al. 2000,Possible role of caspase-3 inhibition in cadmium-induced blockage of apoptosis,"Cadmium (Cd) and chromium (Cr) are human carcinogens. Cr(VI) is taken up into cells and reduced by cellular reductants to the potential DNA damaging species Cr(V), (IV), and (III). Reactive oxygen species and carbon-based radicals may also be produced during Cr reduction. We previously found that Cd blocks Cr-induced apoptosis, which could allow a larger proportion of genetically damaged cells to escape and become transformed. This study helped define the mechanisms of Cd-induced suppression of apoptosis. Chinese hamster ovary (CHO K1-BH4) cells were treated with either Cd (5-20 microM), Cr(VI) (350 microM), or Cd (5-20 microM) plus Cr(VI) (350 microM) for 3 h and then cultured in metal-free media for an additional 48 h at which time DNA was extracted or nuclei were examined to determine apoptosis. Cd markedly reduced Cr-induced DNA fragmentation and reduced the number of Cr-induced apoptotic cell nuclei to control levels. Additional study investigated the biokinetics and cellular metabolism of Cr. Cd did not alter the cellular Cr accumulation and there were no differences in the levels of reduced glutathione, a compound possibly important in Cr reduction and reflective of the cellular reducing environment. The antiapoptotic effect of Cd was not due to diminished cellular reduction of Cr(VI) as assessed by electron-spin resonance determination of the levels of Cr(V). Thus, Cd suppression of Cr-induced apoptosis is not based on altered Cr toxicokinetics or metabolism. In addition to Cr, Cd also inhibited apoptosis induced by hygromycin B and actinomycin D. Cd was a very effective inhibitor of caspase-3 activity, a central mediator of apoptosis, with nontoxic levels of Cd resulting in up to approximately 60% inhibition. These results indicate that Cd may have a generalized inhibitory effect on apoptosis, possibly by inhibiting caspase-3. Inhibition of apoptosis by Cd may allow a greater portion of genetically damaged cells to survive, or give selective growth advantages, and has implications as a potential nongenotoxic mechanism of Cd carcinogenesis.","Possible role of caspase-3 inhibition in cadmium-induced blockage of apoptosis Abs: Cadmium (Cd) and chromium (Cr) are human carcinogens. Cr(VI) is taken up into cells and reduced by cellular reductants to the potential DNA damaging species Cr(V), (IV), and (III). Reactive oxygen species and carbon-based radicals may also be produced during Cr reduction. We previously found that Cd blocks Cr-induced apoptosis, which could allow a larger proportion of genetically damaged cells to escape and become transformed. This study helped define the mechanisms of Cd-induced suppression of apoptosis. Chinese hamster ovary (CHO K1-BH4) cells were treated with either Cd (5-20 microM), Cr(VI) (350 microM), or Cd (5-20 microM) plus Cr(VI) (350 microM) for 3 h and then cultured in metal-free media for an additional 48 h at which time DNA was extracted or nuclei were examined to determine apoptosis. Cd markedly reduced Cr-induced DNA fragmentation and reduced the number of Cr-induced apoptotic cell nuclei to control levels. Additional study investigated the biokinetics and cellular metabolism of Cr. Cd did not alter the cellular Cr accumulation and there were no differences in the levels of reduced glutathione, a compound possibly important in Cr reduction and reflective of the cellular reducing environment. The antiapoptotic effect of Cd was not due to diminished cellular reduction of Cr(VI) as assessed by electron-spin resonance determination of the levels of Cr(V). Thus, Cd suppression of Cr-induced apoptosis is not based on altered Cr toxicokinetics or metabolism. In addition to Cr, Cd also inhibited apoptosis induced by hygromycin B and actinomycin D. Cd was a very effective inhibitor of caspase-3 activity, a central mediator of apoptosis, with nontoxic levels of Cd resulting in up to approximately 60% inhibition. These results indicate that Cd may have a generalized inhibitory effect on apoptosis, possibly by inhibiting caspase-3. Inhibition of apoptosis by Cd may allow a greater portion of genetically damaged cells to survive, or give selective growth advantages, and has implications as a potential nongenotoxic mechanism of Cd carcinogenesis."
180225,Metze et al. 2004,Determination of Cr(VI) in ambient airborne particulate matter by a species-preserving scrubber-sampling technique,"Airborne particulate matter has been sampled at a location close to a metallurgical plant in North-Rhine- Westphalia, Germany, and first results on the chromium( VI) content in the collected dust are presented. A special procedure using a scrubber as sampling device was used to preserve Cr(VI) during the sampling procedure. The scrubber solution which consisted of 0.1 mol L–1 TRIS-buffer solution was adjusted to a slightly alkaline pH of 8.6 to reduce the oxidation potential of Cr(VI) and to avoid possible oxidation of Cr(III) to Cr(VI), for example by oxygen (or ozone at ambient concentrations). After sampling Cr(VI) was pre-concentrated on an anion-exchange material and eluted with aqueous 0.6 mol L–1 sodium perchlorate solution. After elution, a species-selective complex of Cr(VI) with diphenylcarbazide (DPC) was prepared; this was extracted into n-hexanol and quantified by UV–visible spectrophotometry. A detection limit of 0.9 ngm–3 for Cr(VI) in ambient aerosols can be achieved with this method.","Determination of Cr(VI) in ambient airborne particulate matter by a species-preserving scrubber-sampling technique Abs: Airborne particulate matter has been sampled at a location close to a metallurgical plant in North-Rhine- Westphalia, Germany, and first results on the chromium( VI) content in the collected dust are presented. A special procedure using a scrubber as sampling device was used to preserve Cr(VI) during the sampling procedure. The scrubber solution which consisted of 0.1 mol L–1 TRIS-buffer solution was adjusted to a slightly alkaline pH of 8.6 to reduce the oxidation potential of Cr(VI) and to avoid possible oxidation of Cr(III) to Cr(VI), for example by oxygen (or ozone at ambient concentrations). After sampling Cr(VI) was pre-concentrated on an anion-exchange material and eluted with aqueous 0.6 mol L–1 sodium perchlorate solution. After elution, a species-selective complex of Cr(VI) with diphenylcarbazide (DPC) was prepared; this was extracted into n-hexanol and quantified by UV–visible spectrophotometry. A detection limit of 0.9 ngm–3 for Cr(VI) in ambient aerosols can be achieved with this method."
177616,Suedel et al. 2006,The value of metals bioavailability and speciation information for ecological risk assessment in arid soils,"When evaluating the risk chemicals may pose to mammals and birds in ecological risk assessments (ERAs), it is common practice to conservatively assume that all (100%) of a chemical in an environmental medium is bioavailable to receptors. This assumption often leads to overestimating ecological risk and may ultimately result in costly and unnecessary risk management actions. While effects of bioavailability and speciation of metals such as arsenic (As) and lead (Pb) have been considered in human health risk assessment, these effects are rarely taken into consideration when assessing risks to mammals and birds. An ERA was conducted at the former Col-Tex refinery site in Colorado City, Texas, USA, to characterize risks to select wildlife species from exposure to chromium (Cr) and Pb found in soils. The focus on these metals was based on results of a screening-level ERA that found that Cr and Pb were posing ecological risks at the site. Soils were analyzed for total Cr and Pb, trivalent Cr (CrIII), hexavalent Cr (CrVI), organic Pb, and the bioavailability and speciation of Pb. Results for Pb and Cr indicated that >94% of the Cr was present as the less toxic and immobile Cr(III) and that >99% of the Pb in soils was present as inorganic Pb. Lead bioaccessibility measured by in vitro testing ranged from 8% to 77.8%, depending on location of individual soil samples. Results demonstrated that Pb and Cr bioavailability and speciation information can raise soil cleanup concentrations while being protective of ecological receptors. The costs of performing the ERA were de minimus compared to the reduction in remediation costs at the site. The refined hazard estimates allowed informed decision making in the management and segregation of soils, allowing for effective risk management at the site.","The value of metals bioavailability and speciation information for ecological risk assessment in arid soils Abs: When evaluating the risk chemicals may pose to mammals and birds in ecological risk assessments (ERAs), it is common practice to conservatively assume that all (100%) of a chemical in an environmental medium is bioavailable to receptors. This assumption often leads to overestimating ecological risk and may ultimately result in costly and unnecessary risk management actions. While effects of bioavailability and speciation of metals such as arsenic (As) and lead (Pb) have been considered in human health risk assessment, these effects are rarely taken into consideration when assessing risks to mammals and birds. An ERA was conducted at the former Col-Tex refinery site in Colorado City, Texas, USA, to characterize risks to select wildlife species from exposure to chromium (Cr) and Pb found in soils. The focus on these metals was based on results of a screening-level ERA that found that Cr and Pb were posing ecological risks at the site. Soils were analyzed for total Cr and Pb, trivalent Cr (CrIII), hexavalent Cr (CrVI), organic Pb, and the bioavailability and speciation of Pb. Results for Pb and Cr indicated that >94% of the Cr was present as the less toxic and immobile Cr(III) and that >99% of the Pb in soils was present as inorganic Pb. Lead bioaccessibility measured by in vitro testing ranged from 8% to 77.8%, depending on location of individual soil samples. Results demonstrated that Pb and Cr bioavailability and speciation information can raise soil cleanup concentrations while being protective of ecological receptors. The costs of performing the ERA were de minimus compared to the reduction in remediation costs at the site. The refined hazard estimates allowed informed decision making in the management and segregation of soils, allowing for effective risk management at the site."
176357,Nestmann 2005,"Mutation research, genetic toxicology and environmental mutagenesis",,"Mutation research, genetic toxicology and environmental mutagenesis Abs: "
170017,Maeng et al. 2004,Chromosome aberration and lipid peroxidation in chromium-exposed workers,,Chromosome aberration and lipid peroxidation in chromium-exposed workers Abs: 
165940,Zakaria et al. 2007,Hexavalent chromium reduction by Acinetobacter haemolyticussolated from heavy-metal contaminated wastewater,"Possible applicationf a locallysolated environmentalsolate, Acinetobacter haemolyticus to remediate Cr(VI) contaminationn water system wasemonstrated. Cr(VI) reduction by A. haemolyticus seems to favour the lower concentrations (10-30 mg/L). However,ncomplete Cr(VI) reductionccurred at 70-100 mg/L Cr(VI). Initial specific reduction ratencreased with Cr(VI) concentrations. Cr(VI) reduction was not affected by 1r 10 mM sodium azide (metabolicnhibitor), 10 mMf PO(4)3-, SO4(2-), SO(3)2-, NO3-r 30 mg/Lf Pb(II), Zn(II), Cd(II)ons. However, heat treatment caused significantroppedn Cr(VI) reduction to less than 20%nly. A. haemolyticus cells losests shape and size after exposure to 10 and 50 mg Cr(VI)/L as revealed from TEM examination. The presencef electron-dense particlesn the cytoplasmic regionf the bacteria suggestedepositionf chromiumn the cells.","Hexavalent chromium reduction by Acinetobacter haemolyticussolated from heavy-metal contaminated wastewater Abs: Possible applicationf a locallysolated environmentalsolate, Acinetobacter haemolyticus to remediate Cr(VI) contaminationn water system wasemonstrated. Cr(VI) reduction by A. haemolyticus seems to favour the lower concentrations (10-30 mg/L). However,ncomplete Cr(VI) reductionccurred at 70-100 mg/L Cr(VI). Initial specific reduction ratencreased with Cr(VI) concentrations. Cr(VI) reduction was not affected by 1r 10 mM sodium azide (metabolicnhibitor), 10 mMf PO(4)3-, SO4(2-), SO(3)2-, NO3-r 30 mg/Lf Pb(II), Zn(II), Cd(II)ons. However, heat treatment caused significantroppedn Cr(VI) reduction to less than 20%nly. A. haemolyticus cells losests shape and size after exposure to 10 and 50 mg Cr(VI)/L as revealed from TEM examination. The presencef electron-dense particlesn the cytoplasmic regionf the bacteria suggestedepositionf chromiumn the cells."
164639,Wasi et al. 2008,"Biochemical characterization of a multiple heavy metal, pesticides and phenol resistant Pseudomonas fluorescens strain","Pseudomonas fluorescens SM1 isolate was found to be resistant to some major water pollutants namely Cd super(2) super(+), Cr super(6) super(+), Cu super(2) super(+), Ni super(2) super(+), Pb super(2) super(+), BHC, 2,4-D, mancozeb and phenols up to a concentration four times to the normal levels occurring in the highly pollulated regions. Curing experiment brought about the loss of one or more resistance markers indicating the plasmid born resistance. Plasmid profile of SM1 strain showed the presence of one DNA band of 43.6kb. This Plasmid was isolated from SM1 strain and introduced into Escherichia coli DH5 alpha with a transformation frequency of 6.7x10 super(-) super(4)transformants/recipient cell. The test SM1 strain was also capable of biotransforming Cr(VI) to Cr(III) which is less toxic compounds. Present studies further indicated that the test SM1 strain was not only resistant to 2,4-D, phenols and catechol but also capable of bioremediating these toxicants quite efficiently. Moreover, studies with inhibitors like sodium azide, 2,4-DNP and chloramphenicol suggested that the major mechanism for the bioremediation of the heavy metals other than Cr super(6) super(+) would be the biosorption process.","Biochemical characterization of a multiple heavy metal, pesticides and phenol resistant Pseudomonas fluorescens strain Abs: Pseudomonas fluorescens SM1 isolate was found to be resistant to some major water pollutants namely Cd super(2) super(+), Cr super(6) super(+), Cu super(2) super(+), Ni super(2) super(+), Pb super(2) super(+), BHC, 2,4-D, mancozeb and phenols up to a concentration four times to the normal levels occurring in the highly pollulated regions. Curing experiment brought about the loss of one or more resistance markers indicating the plasmid born resistance. Plasmid profile of SM1 strain showed the presence of one DNA band of 43.6kb. This Plasmid was isolated from SM1 strain and introduced into Escherichia coli DH5 alpha with a transformation frequency of 6.7x10 super(-) super(4)transformants/recipient cell. The test SM1 strain was also capable of biotransforming Cr(VI) to Cr(III) which is less toxic compounds. Present studies further indicated that the test SM1 strain was not only resistant to 2,4-D, phenols and catechol but also capable of bioremediating these toxicants quite efficiently. Moreover, studies with inhibitors like sodium azide, 2,4-DNP and chloramphenicol suggested that the major mechanism for the bioremediation of the heavy metals other than Cr super(6) super(+) would be the biosorption process."
164534,Vernay et al. 2007,"Interaction of bioaccumulation of heavy metal chromium with water relation, mineral nutrition and photosynthesis in developed leaves of Lolium perenne L","Contamination by chromium (Cr) is widespread in agricultural soils and industrial sites. This heavy metal represents a risk to human health. In order to gain fundamental insights into the nature of the adaptation to Cr excess, the characterisation of physiological indices, including responses of photosynthetic gas exchange and chlorophyll a fluorescence along with changes in mineral nutrient contents and water status were studied in ray grass (Lolium perenne L.). Increased concentrations of Cr(VI) (0-500 mu M Cr) in the Coic and Lessaint nutrient solution were applied. The growth of Lolium perenne is decreased by chromium and the leaves have lost their pigments. Chromium accumulation was greater in roots than in leaves and reached 2450 and 210 mu gg super(-) super(1) DW, respectively with 500 mu M Cr(VI) in nutrient medium. The physiological parameters were severely reduced by this heavy metal. Cr induced toxicity arising from 100 mu M Cr(VI) and resulted in a modification of mineral content in roots and leaves, especially for Ca, Mg and Fe. The chromium stress decreased CO sub(2) assimilation rates mainly due to stomatal closure, which reduced water loss by transpiration without decreasing the cellular available CO sub(2). The fluorescence parameters associated with photosystem II (PSII) activity and the photochemical activity are modified by chromium. Non-radiative energy dissipation mechanisms were triggered during stress since non-photochemical quenching was increased and efficiency of excitation capture by open centers was reduced.","Interaction of bioaccumulation of heavy metal chromium with water relation, mineral nutrition and photosynthesis in developed leaves of Lolium perenne L Abs: Contamination by chromium (Cr) is widespread in agricultural soils and industrial sites. This heavy metal represents a risk to human health. In order to gain fundamental insights into the nature of the adaptation to Cr excess, the characterisation of physiological indices, including responses of photosynthetic gas exchange and chlorophyll a fluorescence along with changes in mineral nutrient contents and water status were studied in ray grass (Lolium perenne L.). Increased concentrations of Cr(VI) (0-500 mu M Cr) in the Coic and Lessaint nutrient solution were applied. The growth of Lolium perenne is decreased by chromium and the leaves have lost their pigments. Chromium accumulation was greater in roots than in leaves and reached 2450 and 210 mu gg super(-) super(1) DW, respectively with 500 mu M Cr(VI) in nutrient medium. The physiological parameters were severely reduced by this heavy metal. Cr induced toxicity arising from 100 mu M Cr(VI) and resulted in a modification of mineral content in roots and leaves, especially for Ca, Mg and Fe. The chromium stress decreased CO sub(2) assimilation rates mainly due to stomatal closure, which reduced water loss by transpiration without decreasing the cellular available CO sub(2). The fluorescence parameters associated with photosystem II (PSII) activity and the photochemical activity are modified by chromium. Non-radiative energy dissipation mechanisms were triggered during stress since non-photochemical quenching was increased and efficiency of excitation capture by open centers was reduced."
156588,Isakov et al. 2007,A method of assessing air toxics concentrations in urban areas using mobile platform measurements,"The objective of this paper is to demonstrate an approach to characterize the spatial variability in ambient air concentrations using mobile platform measurements. This approach may be useful for air toxics assessments in Environmental Justice applications, epidemiological studies, and environmental health risk assessments. In this study, we developed and applied a method to characterize air toxics concentrations in urban areas using results of the recently conducted field study in Wilmington, DE. Mobile measurements were collected over a 4- x 4-km area of downtown Wilmington for three components: formaldehyde (representative of volatile organic compounds and also photochemically reactive pollutants), aerosol size distribution (representing fine particulate matter), and water-soluble hexavalent chromium (representative of toxic metals). These measurements were,used to construct spatial and temporal distributions of air toxics in the area that show a very strong temporal variability, both diurnally and seasonally. An analysis of spatial variability indicates that all pollutants varied significantly by location, which suggests potential impact of local sources. From the comparison with measurements at the central monitoring site, we conclude that formaldehyde and fine particulates show a positive correlation with temperature, which could also be the reason that photochemically generated formaldehyde and fine particulates over the study area correlate well with the fine particulate matter measured at the central site.","A method of assessing air toxics concentrations in urban areas using mobile platform measurements Abs: The objective of this paper is to demonstrate an approach to characterize the spatial variability in ambient air concentrations using mobile platform measurements. This approach may be useful for air toxics assessments in Environmental Justice applications, epidemiological studies, and environmental health risk assessments. In this study, we developed and applied a method to characterize air toxics concentrations in urban areas using results of the recently conducted field study in Wilmington, DE. Mobile measurements were collected over a 4- x 4-km area of downtown Wilmington for three components: formaldehyde (representative of volatile organic compounds and also photochemically reactive pollutants), aerosol size distribution (representing fine particulate matter), and water-soluble hexavalent chromium (representative of toxic metals). These measurements were,used to construct spatial and temporal distributions of air toxics in the area that show a very strong temporal variability, both diurnally and seasonally. An analysis of spatial variability indicates that all pollutants varied significantly by location, which suggests potential impact of local sources. From the comparison with measurements at the central monitoring site, we conclude that formaldehyde and fine particulates show a positive correlation with temperature, which could also be the reason that photochemically generated formaldehyde and fine particulates over the study area correlate well with the fine particulate matter measured at the central site."
155860,Ince et al. 1999,Assessment of toxic interactions of heavy metals in binary mixtures: a statistical approach,"Toxicity of zinc, copper, cobalt, and chromium ions and their binary interactions were studied at varying test levels by using a battery of two tests, Microtox and duckweed with Vibrio fisheri and Lemna minor as test organisms, respectively. The type of toxic interaction at each test combination was assessed by a statistical approach based on testing the null hypothesis of additive toxicity at 95% confidence level. The interactions were called antagonistic, additive, or synergistic in accordance with the statistical significance and the sign of the difference between the tested hypothesis and the value of the observed toxicity at the binary test level concerned. In the majority of the combinations studied by the two bioassays, the interactions were of antagonistic nature. Additive toxicity was the next frequently predicted interaction in both test results, the frequency being much higher in Microtox responses than in those of duckweed. Finally, synergism was found to be a rare interaction in Microtox results, but totally unlikely in duckweed within the selected test combinations.","Assessment of toxic interactions of heavy metals in binary mixtures: a statistical approach Abs: Toxicity of zinc, copper, cobalt, and chromium ions and their binary interactions were studied at varying test levels by using a battery of two tests, Microtox and duckweed with Vibrio fisheri and Lemna minor as test organisms, respectively. The type of toxic interaction at each test combination was assessed by a statistical approach based on testing the null hypothesis of additive toxicity at 95% confidence level. The interactions were called antagonistic, additive, or synergistic in accordance with the statistical significance and the sign of the difference between the tested hypothesis and the value of the observed toxicity at the binary test level concerned. In the majority of the combinations studied by the two bioassays, the interactions were of antagonistic nature. Additive toxicity was the next frequently predicted interaction in both test results, the frequency being much higher in Microtox responses than in those of duckweed. Finally, synergism was found to be a rare interaction in Microtox results, but totally unlikely in duckweed within the selected test combinations."
155181,Wise et al. 2006,Chronic exposure to particulate chromate induces spindle assembly checkpoint bypass in human lung cells,"One of the hallmarks of lung cancer is chromosome instability (CIN), particularly a tetraploid phenotype, which is normally prevented by the spindle assembly checkpoint. Hexavalent chromium Cr(VI) is an established human lung carcinogen, and Cr(VI) induces tumors at lung bifurcation sites where Cr(VI) particles impact and persist. However, the effects of Cr(VI) on the spindle assembly checkpoint are unknown and little is known about prolonged exposure to particulate Cr(VI). Accordingly, we investigated particulate Cr(VI)-induced bypass of the spindle assembly checkpoint after several days of exposure in WHTBF-6 cells. We found that lead chromate indeed induces spindle assembly checkpoint bypass in human lung cells, as 72, 96, and 120 h treatments with 0.5 or 1 microg/cm2 lead chromate induced significant increases in the percentage of cells with aberrant mitotic figures. For example, treatment with 1 microg/cm2 lead chromate for 96 h induced 11, 12.3, and 14% of cells with premature anaphase, centromere spreading and premature centromere division, respectively. In addition, we found a disruption of mitosis with more cells accumulating in anaphase; cells treated for 96 h increased from 18% in controls to 31% in cells treated with lead chromate. To confirm involvement of the spindle assembly checkpoint, Mad2 expression was used as a marker. Mad2 expression was decreased in cells exposed to chronic treatments of lead chromate, consistent with disruption of the checkpoint. We also found concentration- and time-dependent increases in tetraploid cells, which continued to grow and form colonies. When cells were treated with chronic lead alone there was no increase in aberrant mitotic cells or polyploidy; however, chronic exposure to a soluble Cr(VI) showed an increase in aberrant mitotic cells and polyploidy. These data suggest that lead chromate does induce CIN and may be one mechanism in the development of Cr(VI)-induced lung cancer.","Chronic exposure to particulate chromate induces spindle assembly checkpoint bypass in human lung cells Abs: One of the hallmarks of lung cancer is chromosome instability (CIN), particularly a tetraploid phenotype, which is normally prevented by the spindle assembly checkpoint. Hexavalent chromium Cr(VI) is an established human lung carcinogen, and Cr(VI) induces tumors at lung bifurcation sites where Cr(VI) particles impact and persist. However, the effects of Cr(VI) on the spindle assembly checkpoint are unknown and little is known about prolonged exposure to particulate Cr(VI). Accordingly, we investigated particulate Cr(VI)-induced bypass of the spindle assembly checkpoint after several days of exposure in WHTBF-6 cells. We found that lead chromate indeed induces spindle assembly checkpoint bypass in human lung cells, as 72, 96, and 120 h treatments with 0.5 or 1 microg/cm2 lead chromate induced significant increases in the percentage of cells with aberrant mitotic figures. For example, treatment with 1 microg/cm2 lead chromate for 96 h induced 11, 12.3, and 14% of cells with premature anaphase, centromere spreading and premature centromere division, respectively. In addition, we found a disruption of mitosis with more cells accumulating in anaphase; cells treated for 96 h increased from 18% in controls to 31% in cells treated with lead chromate. To confirm involvement of the spindle assembly checkpoint, Mad2 expression was used as a marker. Mad2 expression was decreased in cells exposed to chronic treatments of lead chromate, consistent with disruption of the checkpoint. We also found concentration- and time-dependent increases in tetraploid cells, which continued to grow and form colonies. When cells were treated with chronic lead alone there was no increase in aberrant mitotic cells or polyploidy; however, chronic exposure to a soluble Cr(VI) showed an increase in aberrant mitotic cells and polyploidy. These data suggest that lead chromate does induce CIN and may be one mechanism in the development of Cr(VI)-induced lung cancer."
145810,Cormier et al. 2006,Origin and Health Impacts of Emissions of Toxic By-Products and Fine Particles from Combustion and Thermal Treatment of Hazardous Wastes and Materials,"High-temperature, controlled incineration and thermal treatment of contaminated soils, sediments, and wastes at Superfund sites are often preferred methods of remediation of contaminated sites under the Comprehensive Environmental Response, Compensation, and Liability Act of 1980 and related legislation. Although these methods may be executed safely, formation of toxic combustion or reaction by-products is still a cause of concern. Emissions of polycyclic aromatic hydrocarbons (PAHs) ; chlorinated hydrocarbons (CHCs) , including polychlorinated dibenzo-p-dioxins and dibenzofurans ; and toxic metals (e.g., chromium VI) have historically been the focus of combustion and health effects research. However, fine particulate matter (PM) and ultrafine PM, which have been documented to be related to cardiovascular disease, pulmonary disease, and cancer, have more recently become the focus of research. Fine PM and ultrafine PM are effective delivery agents for PAHs, CHCs, and toxic metals. In addition, it has recently been realized that brominated hydrocarbons (including brominated/chlorinated dioxins) , redox-active metals, and redox-active persistent free radicals are also associated with PM emissions from combustion and thermal processes. In this article, we discuss the origin of each of these classes of pollutants, the nature of their association with combustion-generated PM, and the mechanisms of their known and potential health impacts.","Origin and Health Impacts of Emissions of Toxic By-Products and Fine Particles from Combustion and Thermal Treatment of Hazardous Wastes and Materials Abs: High-temperature, controlled incineration and thermal treatment of contaminated soils, sediments, and wastes at Superfund sites are often preferred methods of remediation of contaminated sites under the Comprehensive Environmental Response, Compensation, and Liability Act of 1980 and related legislation. Although these methods may be executed safely, formation of toxic combustion or reaction by-products is still a cause of concern. Emissions of polycyclic aromatic hydrocarbons (PAHs) ; chlorinated hydrocarbons (CHCs) , including polychlorinated dibenzo-p-dioxins and dibenzofurans ; and toxic metals (e.g., chromium VI) have historically been the focus of combustion and health effects research. However, fine particulate matter (PM) and ultrafine PM, which have been documented to be related to cardiovascular disease, pulmonary disease, and cancer, have more recently become the focus of research. Fine PM and ultrafine PM are effective delivery agents for PAHs, CHCs, and toxic metals. In addition, it has recently been realized that brominated hydrocarbons (including brominated/chlorinated dioxins) , redox-active metals, and redox-active persistent free radicals are also associated with PM emissions from combustion and thermal processes. In this article, we discuss the origin of each of these classes of pollutants, the nature of their association with combustion-generated PM, and the mechanisms of their known and potential health impacts."
121412,Myers et al. 2008,Hexavalent Chromium Causes the Oxidation of Thioredoxin in Human Bronchial Epithelial Cells,"Hexavalent chromium [Cr(VI)] species such as chromates are cytotoxic. Inhalational exposure is a primary concern in many Cr-related industries and their immediate environments, and bronchial epithelial cells are directly exposed to inhaled Cr(VI). Chromates are readily taken up by cells and are reduced to reactive Cr species which may also result in the generation of reactive oxygen species (ROS). The thioredoxin (Trx) system has a key role in the maintenance of cellular thiol redox balance and is essential for cell survival. Cells normally maintain the cytosolic (Trx1) and mitochondrial (Trx2) thioredoxins largely in the reduced state. Redox Western blots were used to assess the redox status of the thioredoxins in normal human bronchial epithelial cells (BEAS-2B) incubated with soluble Na2CrO4 or insoluble ZnCrO4 for different periods of time. Both chromates caused a dose- and time-dependent oxidation of Trx2 and Trx1. Trx2 was more susceptible in that it could all be converted to the oxidized form, whereas a small amount of reduced Trx1 remained even after prolonged treatment with higher Cr concentrations. Only one of the dithiols, presumably the active site, of Trx1 was oxidized by Cr(VI). Cr(VI) did not cause significant GSH depletion or oxidation indicating that Trx oxidation does not result from a general oxidation of cellular thiols. With purified Trx and thioredoxin reductase (TrxR) in vitro, Cr(VI) also resulted in Trx oxidation. It was determined that purified TrxR has pronounced Cr(VI) reducing activity, so competition for electron flow from TrxR might impair its ability to reduce Trx. The in vitro data also suggested some direct redox interaction between Cr(VI) and Trx. The ability of Cr(VI) to cause Trx oxidation in cells could contribute to its cytotoxic effects, and could have important implications for cell survival, redox-sensitive cell signaling, and the cells’ tolerance of other oxidant insults.","Hexavalent Chromium Causes the Oxidation of Thioredoxin in Human Bronchial Epithelial Cells Abs: Hexavalent chromium [Cr(VI)] species such as chromates are cytotoxic. Inhalational exposure is a primary concern in many Cr-related industries and their immediate environments, and bronchial epithelial cells are directly exposed to inhaled Cr(VI). Chromates are readily taken up by cells and are reduced to reactive Cr species which may also result in the generation of reactive oxygen species (ROS). The thioredoxin (Trx) system has a key role in the maintenance of cellular thiol redox balance and is essential for cell survival. Cells normally maintain the cytosolic (Trx1) and mitochondrial (Trx2) thioredoxins largely in the reduced state. Redox Western blots were used to assess the redox status of the thioredoxins in normal human bronchial epithelial cells (BEAS-2B) incubated with soluble Na2CrO4 or insoluble ZnCrO4 for different periods of time. Both chromates caused a dose- and time-dependent oxidation of Trx2 and Trx1. Trx2 was more susceptible in that it could all be converted to the oxidized form, whereas a small amount of reduced Trx1 remained even after prolonged treatment with higher Cr concentrations. Only one of the dithiols, presumably the active site, of Trx1 was oxidized by Cr(VI). Cr(VI) did not cause significant GSH depletion or oxidation indicating that Trx oxidation does not result from a general oxidation of cellular thiols. With purified Trx and thioredoxin reductase (TrxR) in vitro, Cr(VI) also resulted in Trx oxidation. It was determined that purified TrxR has pronounced Cr(VI) reducing activity, so competition for electron flow from TrxR might impair its ability to reduce Trx. The in vitro data also suggested some direct redox interaction between Cr(VI) and Trx. The ability of Cr(VI) to cause Trx oxidation in cells could contribute to its cytotoxic effects, and could have important implications for cell survival, redox-sensitive cell signaling, and the cells’ tolerance of other oxidant insults."
98798,Talebi 2003,Determination of total and hexavalent chromium concentrations in the atmosphere of the city of Isfahan,"Airborne particulate matter was collected from the atmosphere of the city of Isfahan by a high-volume air sampler. Determination of the concentration of total chromium was carried out by graphite furnace atomic absorption spectrometry after acid digestion. The determination of hexavalent chromium was carried out by ion chromatography following the collection of Cr(vi) in an impinger. Day-to-day variations in concentrations of total and hexavalent chromium were investigated and an excellent similarity was found between them. Atmospheric levels of total and hexavalent chromium were also investigated in different months of the year, and maximum concentrations were found in October.","Determination of total and hexavalent chromium concentrations in the atmosphere of the city of Isfahan Abs: Airborne particulate matter was collected from the atmosphere of the city of Isfahan by a high-volume air sampler. Determination of the concentration of total chromium was carried out by graphite furnace atomic absorption spectrometry after acid digestion. The determination of hexavalent chromium was carried out by ion chromatography following the collection of Cr(vi) in an impinger. Day-to-day variations in concentrations of total and hexavalent chromium were investigated and an excellent similarity was found between them. Atmospheric levels of total and hexavalent chromium were also investigated in different months of the year, and maximum concentrations were found in October."
95748,Zeiger et al. 1992,Salmonella mutagenicity tests: V Results from the testing of 311 chemicals,"#311 chemicals were tested under code, for mutagenicity, in Salmonella typhimurium; 35 of the chemicals were tested more than once in the same or different laboratories. The tests were conducted using a preincubation protocol in the absence of exogenous metabolic activation, and in the presence of liver S-9 from Aroclor-induced male Sprague-Dawley rats and Syrian hamsters. Some of the volatile chemicals were also tested in desiccators. A total of 120 chemicals were mutagenic or weakly mutagenic, 3 were judged questionable, and 172 were non-mutagenic. The remaining 16 chemicals produced different responses in the two or three laboratories in which they were tested. The results and data from these tests are presented.","Salmonella mutagenicity tests: V Results from the testing of 311 chemicals Abs: #311 chemicals were tested under code, for mutagenicity, in Salmonella typhimurium; 35 of the chemicals were tested more than once in the same or different laboratories. The tests were conducted using a preincubation protocol in the absence of exogenous metabolic activation, and in the presence of liver S-9 from Aroclor-induced male Sprague-Dawley rats and Syrian hamsters. Some of the volatile chemicals were also tested in desiccators. A total of 120 chemicals were mutagenic or weakly mutagenic, 3 were judged questionable, and 172 were non-mutagenic. The remaining 16 chemicals produced different responses in the two or three laboratories in which they were tested. The results and data from these tests are presented."
94803,Hughes et al. 1994,Chromium and its compounds: evaluation of risks to health from environmental exposure in Canada,,Chromium and its compounds: evaluation of risks to health from environmental exposure in Canada Abs: 
94801,Kooijman 1987,A safety factor for LC50 values allowing for differences in sensitivity among species,Biosis copyright: biol abs. rrm water pollution model lc-50,A safety factor for LC50 values allowing for differences in sensitivity among species Abs: Biosis copyright: biol abs. rrm water pollution model lc-50
93237,Tomatis et al. 1989,Human carcinogens so far identified,"The massive exploitation of natural resources, of which tobacco and asbestos are two conspicuous, though very different examples, and the synthesis of industrial chemicals have generated new hazards and new carcinogens which have been added to older ones. The majority of the over 50 agents that have been firmly identified so far as being human carcinogens belong to the relatively new hazards, that is environmental chemicals or chemical mixtures to which humans have been exposed only during the last century and a half. They are of more importance for cancer occurring in men than in women, and there is no evidence so far that they are related to cancers occurring at some of the most common target sites in either sex. It would be mistaken to believe that complete cancer prevention could be achieved solely by controlling these new, or relatively new, carcinogenic agents, but it would be similarly wrong to deny the importance of trying to control them and of continuing to do so. The experimental approach for the identification of carcinogens has an irreplaceable role to play in preventing the dispersal into our environment of new hazards and in identifying among the chemicals already in use, those that are carcinogenic. That a closer integration between the epidemiological and the experimental approaches may succeed in substantially reducing the size of the unknown region within the spectrum of cancer-causing factors, is today's hope that awaits confirmation. At the same time, advances in the understanding of the mechanisms underlying the different steps of the process leading to the clinical manifestation of cancer may help in the uncovering of agents and risk factors that the approaches used, at least in the way they have been used until now, may not have been apt to identify.","Human carcinogens so far identified Abs: The massive exploitation of natural resources, of which tobacco and asbestos are two conspicuous, though very different examples, and the synthesis of industrial chemicals have generated new hazards and new carcinogens which have been added to older ones. The majority of the over 50 agents that have been firmly identified so far as being human carcinogens belong to the relatively new hazards, that is environmental chemicals or chemical mixtures to which humans have been exposed only during the last century and a half. They are of more importance for cancer occurring in men than in women, and there is no evidence so far that they are related to cancers occurring at some of the most common target sites in either sex. It would be mistaken to believe that complete cancer prevention could be achieved solely by controlling these new, or relatively new, carcinogenic agents, but it would be similarly wrong to deny the importance of trying to control them and of continuing to do so. The experimental approach for the identification of carcinogens has an irreplaceable role to play in preventing the dispersal into our environment of new hazards and in identifying among the chemicals already in use, those that are carcinogenic. That a closer integration between the epidemiological and the experimental approaches may succeed in substantially reducing the size of the unknown region within the spectrum of cancer-causing factors, is today's hope that awaits confirmation. At the same time, advances in the understanding of the mechanisms underlying the different steps of the process leading to the clinical manifestation of cancer may help in the uncovering of agents and risk factors that the approaches used, at least in the way they have been used until now, may not have been apt to identify."
90525,Shi and  Mao 1994,8-hydroxy-2'-deoxyguanosine formation and DNA damage induced by sulfur trioxide anion radicals,"#The 8-hydroxy-2'-deoxyguanosine (8-OHdG) formation and DNA damage by sulfur trioxide anion radicals (SO3.-) were investigated using ESR spin trapping, HPLC, and electrophoretic assays. Sulfite (SO3(2-) autoxidation generated both hydroxyl (.OH) and SO3.- radicals. Oxidation of SO3(2-) by chromium (VI) generated only SO3.- with much enhanced yield. Incubation of 2'-deoxyguanosine (dG) with SO3(2-) generated 8-OHdG albeit at low yield. Chromium (VI) enhanced the yield four-fold. Electrophoretic assays showed that SO3.- radicals generated by chromium (VI) oxidation of SO3(2-) caused DNA double strand breaks. The results demonstrate that SO3.- radicals are capable of causing dG hydroxylation and DNA double strand breaks.","8-hydroxy-2'-deoxyguanosine formation and DNA damage induced by sulfur trioxide anion radicals Abs: #The 8-hydroxy-2'-deoxyguanosine (8-OHdG) formation and DNA damage by sulfur trioxide anion radicals (SO3.-) were investigated using ESR spin trapping, HPLC, and electrophoretic assays. Sulfite (SO3(2-) autoxidation generated both hydroxyl (.OH) and SO3.- radicals. Oxidation of SO3(2-) by chromium (VI) generated only SO3.- with much enhanced yield. Incubation of 2'-deoxyguanosine (dG) with SO3(2-) generated 8-OHdG albeit at low yield. Chromium (VI) enhanced the yield four-fold. Electrophoretic assays showed that SO3.- radicals generated by chromium (VI) oxidation of SO3(2-) caused DNA double strand breaks. The results demonstrate that SO3.- radicals are capable of causing dG hydroxylation and DNA double strand breaks."
89277,Strawn and  Sparks 2000,Effects of soil organic matter on the kinetics and mechanisms of Pb(II) sorption and desorption in soil,"To improve predictions of the toxicity and threat from Pb contaminated soil, it is critical that time-dependent sorption and desorption behavior be understood. In this paper, the sorption and desorption behavior ( , ) of Pb in a Matapeake silt loam soil (Typic Hapludult) were studied by stirred-flow and batch experiments. In addition, we studied the effects of soil organic matter (SOM) on sorption and desorption behavior by treating the soil with sodium hypochlorite to remove the SOM fraction, and using a soil with six times as much SOM (St. Johns loamy sand [Typic Haplaquods]) as the Matapeake soil. Lead sorption consisted of a fast initial reaction in which all of the Pb added to the stirred-flow chamber was sorbed. Following this initial fast reaction, sorption continued and appears to be rate limited (indicated by a decrease in the outflow concentration when the flow rate was decreased, or when the flow was stopped). The total amount of Pb sorbed was 102, 44, and 27 mmol kg-1 for the St. Johns soil and the untreated and treated Matapeake soils, respectively. Desorption experiments were conducted on the soils with the background electrolyte as the eluent in the stirred-flow chamber. In the St. Johns soil only, 32% of the total sorbed Pb was desorbed, while 47 and 76% of the sorbed Pb was released from the untreated and treated Matapeake soil, respectively. The correlation between SOM in the soils, and the percentage Pb desorbed from the soils suggests that SOM plays an important role in slow desorption reactions of Pb from soil materials. Aging experiments in which sorbed Pb was incubated for 1, 10, and 32 d showed that sorption incubation time had no effect on Pb desorption behavior. Analysis of the treated and untreated Matapeake soils by x-ray absorption fine structure (XAFS) spectroscopy revealed that the local atomic structure of sorbed Pb is distinctly different in the two samples. In the soil treated to remove SOM, the data were well represented by theoretical models using O, Si, and Pb backscattering atoms. In the untreated soil, the XAFS data were best described by O and C backscatterers. These XAFS results confirm that the sorption mechanisms in the two systems are different.","Effects of soil organic matter on the kinetics and mechanisms of Pb(II) sorption and desorption in soil Abs: To improve predictions of the toxicity and threat from Pb contaminated soil, it is critical that time-dependent sorption and desorption behavior be understood. In this paper, the sorption and desorption behavior ( , ) of Pb in a Matapeake silt loam soil (Typic Hapludult) were studied by stirred-flow and batch experiments. In addition, we studied the effects of soil organic matter (SOM) on sorption and desorption behavior by treating the soil with sodium hypochlorite to remove the SOM fraction, and using a soil with six times as much SOM (St. Johns loamy sand [Typic Haplaquods]) as the Matapeake soil. Lead sorption consisted of a fast initial reaction in which all of the Pb added to the stirred-flow chamber was sorbed. Following this initial fast reaction, sorption continued and appears to be rate limited (indicated by a decrease in the outflow concentration when the flow rate was decreased, or when the flow was stopped). The total amount of Pb sorbed was 102, 44, and 27 mmol kg-1 for the St. Johns soil and the untreated and treated Matapeake soils, respectively. Desorption experiments were conducted on the soils with the background electrolyte as the eluent in the stirred-flow chamber. In the St. Johns soil only, 32% of the total sorbed Pb was desorbed, while 47 and 76% of the sorbed Pb was released from the untreated and treated Matapeake soil, respectively. The correlation between SOM in the soils, and the percentage Pb desorbed from the soils suggests that SOM plays an important role in slow desorption reactions of Pb from soil materials. Aging experiments in which sorbed Pb was incubated for 1, 10, and 32 d showed that sorption incubation time had no effect on Pb desorption behavior. Analysis of the treated and untreated Matapeake soils by x-ray absorption fine structure (XAFS) spectroscopy revealed that the local atomic structure of sorbed Pb is distinctly different in the two samples. In the soil treated to remove SOM, the data were well represented by theoretical models using O, Si, and Pb backscattering atoms. In the untreated soil, the XAFS data were best described by O and C backscatterers. These XAFS results confirm that the sorption mechanisms in the two systems are different."
88704,Besser et al. 2004,"Effects of sediment characteristics on the toxicity of chromium(III) and chromium(VI) to the amphipod, Hyalella azteca","We evaluated the influence of sediment characteristics, acid-volatile sulfide (AVS) and organic matter (OM), on the toxicity of chromium (Cr) in freshwater sediments. We conducted chronic (28-42-d) toxicity tests with the amphipod Hyalella azteca exposed to Cr(VI) and Cr(III) in water and in spiked sediments. Waterborne Cr(VI) caused reduced survival of amphipods with a median lethal concentration (LC50) of 40 mug/L. Cr(VI) spiked into test sediments with differing levels of AVS resulted in graded decreases in AVS and sediment OM. Only Cr(VI)-spiked sediments with low AVS concentrations (<1 mumol/g) caused significant amphipod mortality. Waterborne Cr(III) concentrations near solubility limits caused decreased survival of amphipods at pH 7 and pH 8 but not at pH 6. Sediments spiked with high levels of Cr(III) did not affect amphipod survival but had minor effects on growth and inconsistent effects on reproduction. Pore waters of some Cr(III)-spiked sediments contained measurable concentrations of Cr(VI), but observed toxic effects did not correspond closely to Cr concentrations in sediment or pore waters. Our results indicate that risks of Cr toxicity are low in freshwater sediments containing substantial concentrations of AVS.","Effects of sediment characteristics on the toxicity of chromium(III) and chromium(VI) to the amphipod, Hyalella azteca Abs: We evaluated the influence of sediment characteristics, acid-volatile sulfide (AVS) and organic matter (OM), on the toxicity of chromium (Cr) in freshwater sediments. We conducted chronic (28-42-d) toxicity tests with the amphipod Hyalella azteca exposed to Cr(VI) and Cr(III) in water and in spiked sediments. Waterborne Cr(VI) caused reduced survival of amphipods with a median lethal concentration (LC50) of 40 mug/L. Cr(VI) spiked into test sediments with differing levels of AVS resulted in graded decreases in AVS and sediment OM. Only Cr(VI)-spiked sediments with low AVS concentrations (<1 mumol/g) caused significant amphipod mortality. Waterborne Cr(III) concentrations near solubility limits caused decreased survival of amphipods at pH 7 and pH 8 but not at pH 6. Sediments spiked with high levels of Cr(III) did not affect amphipod survival but had minor effects on growth and inconsistent effects on reproduction. Pore waters of some Cr(III)-spiked sediments contained measurable concentrations of Cr(VI), but observed toxic effects did not correspond closely to Cr concentrations in sediment or pore waters. Our results indicate that risks of Cr toxicity are low in freshwater sediments containing substantial concentrations of AVS."
87002,Fox 1987,Air pollution,BIOSIS COPYRIGHT: BIOL ABS. RRM REVIEW SAMPLING,Air pollution Abs: BIOSIS COPYRIGHT: BIOL ABS. RRM REVIEW SAMPLING
85705,Wise et al. 2005,Human lung cell growth is not stimulated by lead ions after lead chromate-induced genotoxicity,"Chromate compounds are known human lung carcinogens. Water solubility is an important factor in the carcinogenicity of these compounds with the most potent carcinogenic compounds being water-insoluble or 'particulate'. Previously we have shown that particulate chromates dissolve extracellularly releasing chromium (Cr) and lead (Pb) ions and only the Cr ions induce genotoxicity. Pb ions have been considered to have epigenetic effects and it is thought that these may enhance the carcinogenic activity of lead chromate, perhaps by stimulating Cr-damaged cells to divide. However, this possibility has not been directly tested. Accordingly, we investigated the ability of Pb ions to stimulate human lung cells and possibly force lead chromate-damaged cells to grow. We found that at concentrations of lead chromate that induced damage, human lung cells exhibited cell cycle arrest and growth inhibition that were very similar to those observed for sodium chromate. Moreover, we found that soluble Pb ions were not growth stimulatory to human lung cells and in fact induced progressive mitotic arrest. These data indicate that lead chromate-generated Cr ions cause growth inhibition and cell cycle arrest and that Pb does not induce epigenetic effects that stimulate chromate-damaged cells to grow.","Human lung cell growth is not stimulated by lead ions after lead chromate-induced genotoxicity Abs: Chromate compounds are known human lung carcinogens. Water solubility is an important factor in the carcinogenicity of these compounds with the most potent carcinogenic compounds being water-insoluble or 'particulate'. Previously we have shown that particulate chromates dissolve extracellularly releasing chromium (Cr) and lead (Pb) ions and only the Cr ions induce genotoxicity. Pb ions have been considered to have epigenetic effects and it is thought that these may enhance the carcinogenic activity of lead chromate, perhaps by stimulating Cr-damaged cells to divide. However, this possibility has not been directly tested. Accordingly, we investigated the ability of Pb ions to stimulate human lung cells and possibly force lead chromate-damaged cells to grow. We found that at concentrations of lead chromate that induced damage, human lung cells exhibited cell cycle arrest and growth inhibition that were very similar to those observed for sodium chromate. Moreover, we found that soluble Pb ions were not growth stimulatory to human lung cells and in fact induced progressive mitotic arrest. These data indicate that lead chromate-generated Cr ions cause growth inhibition and cell cycle arrest and that Pb does not induce epigenetic effects that stimulate chromate-damaged cells to grow."
85599,Neilan et al. 1983,Effect of low-level lead exposure on antibody-dependent and natural killer cell-mediated cytotoxicity,"Splenic antibody-dependent, cell-mediated cytotoxicity against chicken red blood cell targets [ADCC (CRBC)] and natural killer cell-mediated cytotoxicity (NKMC) were determined in C57BL/6 mice given 1300 ppm lead acetate (827 ppm lead) in their drinking water for 8 weeks. ADCC in lead exposed mice was significantly lower than controls at effector to target cell ratios of 100:1, 50:1, and 25:1. In contrast, no significant difference in unstimulated NKMC was seen in lead exposed mice and control mice at effector to target cell ratios of 200:1, 100:1, and 50:1. Moreover, in vivo poly I:C-enhanced NKMC in lead-treated mice was similar to controls at an effector to target cell ratio of 200:1. Blood lead levels averaged 40.5 +/- 1.2 micrograms% in lead-exposed mice and 1.9 +/- 0.3 micrograms% in controls. These findings suggest that chronic low-level lead exposure in mice results in significant suppression of ADCC (CRBC) but does not alter natural killer activity.","Effect of low-level lead exposure on antibody-dependent and natural killer cell-mediated cytotoxicity Abs: Splenic antibody-dependent, cell-mediated cytotoxicity against chicken red blood cell targets [ADCC (CRBC)] and natural killer cell-mediated cytotoxicity (NKMC) were determined in C57BL/6 mice given 1300 ppm lead acetate (827 ppm lead) in their drinking water for 8 weeks. ADCC in lead exposed mice was significantly lower than controls at effector to target cell ratios of 100:1, 50:1, and 25:1. In contrast, no significant difference in unstimulated NKMC was seen in lead exposed mice and control mice at effector to target cell ratios of 200:1, 100:1, and 50:1. Moreover, in vivo poly I:C-enhanced NKMC in lead-treated mice was similar to controls at an effector to target cell ratio of 200:1. Blood lead levels averaged 40.5 +/- 1.2 micrograms% in lead-exposed mice and 1.9 +/- 0.3 micrograms% in controls. These findings suggest that chronic low-level lead exposure in mice results in significant suppression of ADCC (CRBC) but does not alter natural killer activity."
85201,Davies 1984,Long term mortality study of chromate pigment workers who suffered lead poisoning,"Long term mortality was studied in a group of 57 chromate pigment workers who suffered clinical lead poisoning, mostly between 1930 and 1945. One death was attributed to lead poisoning and there were significant excesses of deaths from nephritis (observed/expected 3/0.24) and cerebrovascular disease (9/2.20), as well as non-significant excesses for respiratory diseases (7/3.59) and accidents and violence (3/1.13). The deaths from nephritis followed long spells of service exceeding 10 years. Poisoning appeared to have more adverse long term effects on older workers: 15 men aged 40 or over at the time of acute poisoning experienced generally high mortality, and 30 years later or by the end of 1981 only two survived instead of the seven expected. The risk of cerebrovascular disease appeared to be unrelated to duration of exposure and affected even men employed for under one year. Excluding the 57 lead poisoned men, other contemporary workers at the factories showed no excess mortality from cerebrovascular disease.","Long term mortality study of chromate pigment workers who suffered lead poisoning Abs: Long term mortality was studied in a group of 57 chromate pigment workers who suffered clinical lead poisoning, mostly between 1930 and 1945. One death was attributed to lead poisoning and there were significant excesses of deaths from nephritis (observed/expected 3/0.24) and cerebrovascular disease (9/2.20), as well as non-significant excesses for respiratory diseases (7/3.59) and accidents and violence (3/1.13). The deaths from nephritis followed long spells of service exceeding 10 years. Poisoning appeared to have more adverse long term effects on older workers: 15 men aged 40 or over at the time of acute poisoning experienced generally high mortality, and 30 years later or by the end of 1981 only two survived instead of the seven expected. The risk of cerebrovascular disease appeared to be unrelated to duration of exposure and affected even men employed for under one year. Excluding the 57 lead poisoned men, other contemporary workers at the factories showed no excess mortality from cerebrovascular disease."
84982,Goldhaber and  Chessin 1997,Comparison of hazardous air pollutant health risk benchmarks,BIOSIS COPYRIGHT: BIOL ABS. RRM JOURNAL ARTICLE POLLUTION GOVERNMENT AND LAW CLEAN AIR ACT AMENDMENTS OF 1990 AIR POLLUTION TOXIC CHEMICALS RELEASE REDUCTIONS POLLUTANT EMISSION SOURCES HEALTH RISK BENCHMARKS RISK ASSESSMENT GUIDELINES EPA TOXICOLOGY GOVERNMENT AGENCY,Comparison of hazardous air pollutant health risk benchmarks Abs: BIOSIS COPYRIGHT: BIOL ABS. RRM JOURNAL ARTICLE POLLUTION GOVERNMENT AND LAW CLEAN AIR ACT AMENDMENTS OF 1990 AIR POLLUTION TOXIC CHEMICALS RELEASE REDUCTIONS POLLUTANT EMISSION SOURCES HEALTH RISK BENCHMARKS RISK ASSESSMENT GUIDELINES EPA TOXICOLOGY GOVERNMENT AGENCY
84372,Blankenship et al. 1997,Induction of apoptotic cell death by particulate lead chromate: differential effects of vitamins C and E on genotoxicity and survival,"Certain hexavalent chromium compounds are documented human carcinogens. Exposure of cells to particulate forms of chromium results in cell-enhanced dissolution of particles in the extracellular microenvironment and chronic production of chromium oxyanions, which are taken up by the cell through an anion transport system and are genotoxic and clastogenic. It was previously shown that apoptosis is the mode of cell death of nearly all of the Chinese hamster ovary cells (CHO-AA8 cell line), which die after high-dose, short-term treatments with soluble sodium chromate. In this report the mode of cell killing by particulate lead chromate and of low-dose continuous treaments of soluble sodium chromate designed to mimic conditions of ionic chromate uptake after lead chromate exposure was examined. CHO-AA8 cells were treated for 24 hr with doses of sodium chromate or lead chromate which cause a 50% decrease in survival in colony-forming effeciency assays. Longer treatments (up to 72 hr) at the same doses did not decrease survival further than the 24-hr exposure. Morphological changes indicative of apoptosis, as well as internucleosomal DNA fragmentation, were detectable by 24 hr after treatment with lead chromate or soluble sodium chromate. All of the cells killed by treatments with lead chromate particles underwent apoptosis as the mode of cell death and this was accurately modeled in cell culture by continuous treatments with low-dose soluble sodium chromate. Exposure of cells to hexavalent chromium compounds causes a spectrum of DNA damage which can be selectively altered by pretreatment of cells with antioxidant vitamins prior to chromium exposure. Here we show that ascorbate and alpha-tocopherol markedly inhibited the chromosomal aberrations induced by both particulate and soluble chromate compounds, even though chromium adduct levels were not decreased by either vitamin pretreatment. Cell survival assays showed that ascorbate, but not alpha-tocopherol, protected cells from apoptosis induced by sodium chromate. The results differentiate chromium-induced apoptosis from both chromosomal damage and adduct levels and suggest that other lesions sensitive to ascorbate but not tocopherol are the proximal inducing signal for chromium-induced apoptosis.","Induction of apoptotic cell death by particulate lead chromate: differential effects of vitamins C and E on genotoxicity and survival Abs: Certain hexavalent chromium compounds are documented human carcinogens. Exposure of cells to particulate forms of chromium results in cell-enhanced dissolution of particles in the extracellular microenvironment and chronic production of chromium oxyanions, which are taken up by the cell through an anion transport system and are genotoxic and clastogenic. It was previously shown that apoptosis is the mode of cell death of nearly all of the Chinese hamster ovary cells (CHO-AA8 cell line), which die after high-dose, short-term treatments with soluble sodium chromate. In this report the mode of cell killing by particulate lead chromate and of low-dose continuous treaments of soluble sodium chromate designed to mimic conditions of ionic chromate uptake after lead chromate exposure was examined. CHO-AA8 cells were treated for 24 hr with doses of sodium chromate or lead chromate which cause a 50% decrease in survival in colony-forming effeciency assays. Longer treatments (up to 72 hr) at the same doses did not decrease survival further than the 24-hr exposure. Morphological changes indicative of apoptosis, as well as internucleosomal DNA fragmentation, were detectable by 24 hr after treatment with lead chromate or soluble sodium chromate. All of the cells killed by treatments with lead chromate particles underwent apoptosis as the mode of cell death and this was accurately modeled in cell culture by continuous treatments with low-dose soluble sodium chromate. Exposure of cells to hexavalent chromium compounds causes a spectrum of DNA damage which can be selectively altered by pretreatment of cells with antioxidant vitamins prior to chromium exposure. Here we show that ascorbate and alpha-tocopherol markedly inhibited the chromosomal aberrations induced by both particulate and soluble chromate compounds, even though chromium adduct levels were not decreased by either vitamin pretreatment. Cell survival assays showed that ascorbate, but not alpha-tocopherol, protected cells from apoptosis induced by sodium chromate. The results differentiate chromium-induced apoptosis from both chromosomal damage and adduct levels and suggest that other lesions sensitive to ascorbate but not tocopherol are the proximal inducing signal for chromium-induced apoptosis."
83781,Devalia et al. 1993,Human bronchial epithelial cell dysfunction following in vitro exposure to nitrogen dioxide,"The effects on human bronchial epithelial cells (BEC) of in-vitro exposure to nitrogen-dioxide (10102440) (NO2) were investigated. Bronchial tissue was obtained from 12 patients, all of whom were smokers, and BEC were cultured. Exposure to NO2 was carried out in an airtight polycarbonate chamber.BEC membrane damage was assessed by estimating the release of chromium-51 (Cr-51) from cells radiolabeled with sodium-chromate. Ciliary beat frequency (CBF) was measured by a modification of the analog contrast enhancement technique. The ability of NO2 to induce generation of leukotriene-C4 (LTC4) was assessed by radioimmunoassay. Results showed that NO2 did not cause any gross cellular damage or detachment of cell monolayers. However, significant release of Cr-51 above baseline levels at NO2 exposures of 400 and 800 parts per billion (ppb) was noted. Cell permeability also increased at all concentrations of 100 to 800ppb. NO2 decreased the CBF of BEC in-vitro slightly at 100 and 400ppb by 2.3 and 3.0, respectively, but at 800ppb it rose to 6.8%, and at 2,000ppb a significant attenuation of 14.2 was noted. LTC4 synthesis was significantly increased at 400 and 800ppb. The authors conclude that acute exposure of human BECs to NO2 may result in cell membrane damage that could play a role in the etiology of bronchial disease such as asthma.","Human bronchial epithelial cell dysfunction following in vitro exposure to nitrogen dioxide Abs: The effects on human bronchial epithelial cells (BEC) of in-vitro exposure to nitrogen-dioxide (10102440) (NO2) were investigated. Bronchial tissue was obtained from 12 patients, all of whom were smokers, and BEC were cultured. Exposure to NO2 was carried out in an airtight polycarbonate chamber.BEC membrane damage was assessed by estimating the release of chromium-51 (Cr-51) from cells radiolabeled with sodium-chromate. Ciliary beat frequency (CBF) was measured by a modification of the analog contrast enhancement technique. The ability of NO2 to induce generation of leukotriene-C4 (LTC4) was assessed by radioimmunoassay. Results showed that NO2 did not cause any gross cellular damage or detachment of cell monolayers. However, significant release of Cr-51 above baseline levels at NO2 exposures of 400 and 800 parts per billion (ppb) was noted. Cell permeability also increased at all concentrations of 100 to 800ppb. NO2 decreased the CBF of BEC in-vitro slightly at 100 and 400ppb by 2.3 and 3.0, respectively, but at 800ppb it rose to 6.8%, and at 2,000ppb a significant attenuation of 14.2 was noted. LTC4 synthesis was significantly increased at 400 and 800ppb. The authors conclude that acute exposure of human BECs to NO2 may result in cell membrane damage that could play a role in the etiology of bronchial disease such as asthma."
82903,Dave 1992,"Sediment toxicity in lakes along the river Kolbacksan, central Sweden","The River Kolbacksan system is located in a historical mining and steel works district of central Sweden. Ten years ago, intensive limnological studies indicated that the sediments in many of the lakes of this system were contaminated with metals and oil (grease). More recently a very high toxicity was found in the sediments from some of these lakes in tests with Daphnia magna and Tubifex tubifex. The objective of this study was to determine the toxicity to Daphnia magna of surficial sediments from representative locations (N = 39) within this system of lakes and to look for possible correlations with concentrations of metals (Cd, Cr, Cu, Hg, Ni, Pb, Zn) and oil (total) analysed in parallel samples. These results were also compared with spiked sediment toxicity data generated for these metals and with the bottom fauna at 8 of the 39 locations. Among the metals analyzed, only Cd, Pb and Zn were correlated with whole sediment toxicity. Only for Zn and Cr did the maximum concentrations approach those that were toxic in the spiked sediments. Correlations using single and combined metal contamination and toxicity (additive models) explained 16% of the sediment toxicity (r 2 = 0.16; N = 39). Significant correlations with the bottom fauna in situ (gross abundance, biomass and species richness) were found for whole sediment toxicity, but not for metal contamination (N = 8). The use of the sediment quality triad approach for assessment of sediment quality is exemplified with a numerical normalization procedure for the latter 8 sites.","Sediment toxicity in lakes along the river Kolbacksan, central Sweden Abs: The River Kolbacksan system is located in a historical mining and steel works district of central Sweden. Ten years ago, intensive limnological studies indicated that the sediments in many of the lakes of this system were contaminated with metals and oil (grease). More recently a very high toxicity was found in the sediments from some of these lakes in tests with Daphnia magna and Tubifex tubifex. The objective of this study was to determine the toxicity to Daphnia magna of surficial sediments from representative locations (N = 39) within this system of lakes and to look for possible correlations with concentrations of metals (Cd, Cr, Cu, Hg, Ni, Pb, Zn) and oil (total) analysed in parallel samples. These results were also compared with spiked sediment toxicity data generated for these metals and with the bottom fauna at 8 of the 39 locations. Among the metals analyzed, only Cd, Pb and Zn were correlated with whole sediment toxicity. Only for Zn and Cr did the maximum concentrations approach those that were toxic in the spiked sediments. Correlations using single and combined metal contamination and toxicity (additive models) explained 16% of the sediment toxicity (r 2 = 0.16; N = 39). Significant correlations with the bottom fauna in situ (gross abundance, biomass and species richness) were found for whole sediment toxicity, but not for metal contamination (N = 8). The use of the sediment quality triad approach for assessment of sediment quality is exemplified with a numerical normalization procedure for the latter 8 sites."
82757,Kerger et al. 1997,"Ingestion of chromium (VI) in drinking water by human volunteers: absorption, distribution, and excretion of single and repeated doses","This study examines the magnitude of hexavalent chromium [Cr(VI)] absorption, distribution, and excretion following oral exposure to 5 and 10 mg Cr(VI)/L in drinking water administered as a single bolus dose (0.5 L swallowed in 2 min) or for 3 d at a dosage of 1 L/d (3 doses of 0.33 L each day, at 6-h intervals). Adult male volunteers ingested deionized water containing various concentrations of potassium chromate, and samples of urine, plasma, and red blood cells (RBCs) were collected and analyzed for total chromium throughout the studies. In the bolus dose studies, a fairly consistent pattern of urinary chromium excretion was observed, with an average half life of about 39 h. However, 4-d total urinary chromium excretion and peak concentrations in urine and blood varied considerably among the 5 volunteers. Studies of repeated exposure to smaller volumes ingested at a more gradual rate (i.e., 0.33 L over 5-15 min) showed similar urinary chromium excretion patterns but generally lower chromium uptake/excretion. Given that sustained elevations in RBC chromium levels provide a specific indication of chromium absorption in the hexavalent state, these data suggest that virtually all (&gt; 99.7%) of the ingested Cr(VI) at 5 and 10 mg Cr(VI)/L was reduced to Cr(III) before entering the blood-stream. The interindividual differences in total chromium uptake and excretion are plausibly explained by ingestion of appreciable doses on an empty stomach, which likely results in the formation of well-absorbed Cr(III) organic complexes in gastrointestinal tissues and possibly the blood. The lack of any clinical indications of toxicity in the volunteers and the patterns of blood uptake and urinary excretion of chromium are consistent with a predominant uptake of Cr(III) organic complexes [derived from Cr(VI)] that are excreted more slowly than inorganic forms of Cr(III). Therefore, it appears that the endogenous reducing agents within the upper gastrointestinal tract and the blood provide sufficient reducing potential to prevent any substantial systemic uptake of Cr(VI) following drinking-water exposures at 5-10 mg Cr(VI)/L. Based on these data, the chemical environment in the gastrointestinal tract and the blood is effective even under relative fasting conditions in reducing Cr(VI) to one or more forms of Cr(III).","Ingestion of chromium (VI) in drinking water by human volunteers: absorption, distribution, and excretion of single and repeated doses Abs: This study examines the magnitude of hexavalent chromium [Cr(VI)] absorption, distribution, and excretion following oral exposure to 5 and 10 mg Cr(VI)/L in drinking water administered as a single bolus dose (0.5 L swallowed in 2 min) or for 3 d at a dosage of 1 L/d (3 doses of 0.33 L each day, at 6-h intervals). Adult male volunteers ingested deionized water containing various concentrations of potassium chromate, and samples of urine, plasma, and red blood cells (RBCs) were collected and analyzed for total chromium throughout the studies. In the bolus dose studies, a fairly consistent pattern of urinary chromium excretion was observed, with an average half life of about 39 h. However, 4-d total urinary chromium excretion and peak concentrations in urine and blood varied considerably among the 5 volunteers. Studies of repeated exposure to smaller volumes ingested at a more gradual rate (i.e., 0.33 L over 5-15 min) showed similar urinary chromium excretion patterns but generally lower chromium uptake/excretion. Given that sustained elevations in RBC chromium levels provide a specific indication of chromium absorption in the hexavalent state, these data suggest that virtually all (&gt; 99.7%) of the ingested Cr(VI) at 5 and 10 mg Cr(VI)/L was reduced to Cr(III) before entering the blood-stream. The interindividual differences in total chromium uptake and excretion are plausibly explained by ingestion of appreciable doses on an empty stomach, which likely results in the formation of well-absorbed Cr(III) organic complexes in gastrointestinal tissues and possibly the blood. The lack of any clinical indications of toxicity in the volunteers and the patterns of blood uptake and urinary excretion of chromium are consistent with a predominant uptake of Cr(III) organic complexes [derived from Cr(VI)] that are excreted more slowly than inorganic forms of Cr(III). Therefore, it appears that the endogenous reducing agents within the upper gastrointestinal tract and the blood provide sufficient reducing potential to prevent any substantial systemic uptake of Cr(VI) following drinking-water exposures at 5-10 mg Cr(VI)/L. Based on these data, the chemical environment in the gastrointestinal tract and the blood is effective even under relative fasting conditions in reducing Cr(VI) to one or more forms of Cr(III)."
82756,Finley et al. 1997,Human ingestion of chromium (VI) in drinking water: pharmacokinetics following repeated exposure,"Regulatory agencies have established safe drinking water concentrations for hexavalent chromium [Cr(VI)] based in part on the presumed capability of human gastric juices to rapidly reduce Cr(VI) to nontoxic trivalent chromium [Cr(III)] prior to systemic absorption. This study examines dose-related pharmacokinetics in humans following repeated oral exposure to Cr(VI) in drinking water. In particular, we sought to examine whether plausible drinking water exposures to Cr(VI) caused a sustained increase in red blood cell chromium levels, a specific marker for systemic uptake of Cr(VI). Adult male volunteers ingested a liter (in three volumes of 333 ml, at approximate 6-hr intervals) of deionized water containing Cr(VI) concentrations ranging from 0.1 to 10.0 mg/liter. Samples of urine, plasma, and red blood cells were collected and analyzed for chromium. A dose-related increase in urinary chromium excretion was observed in all volunteers. Red blood cell and plasma chromium concentrations became elevated in certain individuals at the highest doses. The RBC chromium profiles suggest that the ingested Cr(VI) was reduced to Cr(III) before entering the bloodstream, since the chromium concentration in the RBCs dropped rapidly postexposure. These findings suggest that the human gastrointestinal tract has the capacity to reduce ingested Cr(VI) following ingestion of up to 1 liter of water containing 10.0 mg/liter of Cr(VI), which is consistent with USEPA's position that the Cr(VI) drinking water standard of 0.10 mg Cr(VI)/liter is below the reductive capacity of the stomach.","Human ingestion of chromium (VI) in drinking water: pharmacokinetics following repeated exposure Abs: Regulatory agencies have established safe drinking water concentrations for hexavalent chromium [Cr(VI)] based in part on the presumed capability of human gastric juices to rapidly reduce Cr(VI) to nontoxic trivalent chromium [Cr(III)] prior to systemic absorption. This study examines dose-related pharmacokinetics in humans following repeated oral exposure to Cr(VI) in drinking water. In particular, we sought to examine whether plausible drinking water exposures to Cr(VI) caused a sustained increase in red blood cell chromium levels, a specific marker for systemic uptake of Cr(VI). Adult male volunteers ingested a liter (in three volumes of 333 ml, at approximate 6-hr intervals) of deionized water containing Cr(VI) concentrations ranging from 0.1 to 10.0 mg/liter. Samples of urine, plasma, and red blood cells were collected and analyzed for chromium. A dose-related increase in urinary chromium excretion was observed in all volunteers. Red blood cell and plasma chromium concentrations became elevated in certain individuals at the highest doses. The RBC chromium profiles suggest that the ingested Cr(VI) was reduced to Cr(III) before entering the bloodstream, since the chromium concentration in the RBCs dropped rapidly postexposure. These findings suggest that the human gastrointestinal tract has the capacity to reduce ingested Cr(VI) following ingestion of up to 1 liter of water containing 10.0 mg/liter of Cr(VI), which is consistent with USEPA's position that the Cr(VI) drinking water standard of 0.10 mg Cr(VI)/liter is below the reductive capacity of the stomach."
82755,Kerger et al. 1996,Absorption and elimination of trivalent and hexavalent chromium in humans following ingestion of a bolus dose in drinking water,"These studies investigate the magnitude and valence state of chromium absorbed following plausible drinking water exposures to chromium(VI). Four adult male volunteers ingested a single dose of 5 mg Cr (in 0.5 liters deionized water) in three choromium mixtures: (1) Cr(III) chloride (CrCl3), (2) potassium dichromate reduced with orange juice (cr(III)-OJ); and (3) potassium dichromate [Cr(VI)]. Blood and urine chromium levels were followed for 1-3 days prior to and up to 12 days after ingestion. The three mixtures showed quite different pharmacokinetic patterns. CrCl3 was poorly absorbed (estimated 0.13% bioavailability) and rapidly eliminated in urine (excretion half-life, approximately 10 hr), whereas Cr(III)-OJ was absorbed more efficiently (0.60% bioavailability) but more slowly (half-life, approximately 17 hr), and Cr(VI) had the highest bioavailability (6.9%) and the longest half-life (approximately 39 hr). All three chromium mixtures caused temporary elevations in red blood cell (RBC) and plasma chromium concentrations, but the magnitude and duration of elevation showed a clear trend (Cr(VI) &gt; Cr(III)-OJ &gt; CrCl3). The data suggest that nearly all the ingested Cr(VI) was reduced to Cr(III) before entering the bloodstream based on comparison to RBC and plasma chromium patterns in animals exposed to high doses of Cr(VI). These findings support our prior work which suggests that water-soluble organic complexes of Cr(III) formed during the reduction of Cr(VI) in vivo explain the patterns of blood uptake and urinary excretion in humans at drinking water concentrations of 10 mg/liter or less.","Absorption and elimination of trivalent and hexavalent chromium in humans following ingestion of a bolus dose in drinking water Abs: These studies investigate the magnitude and valence state of chromium absorbed following plausible drinking water exposures to chromium(VI). Four adult male volunteers ingested a single dose of 5 mg Cr (in 0.5 liters deionized water) in three choromium mixtures: (1) Cr(III) chloride (CrCl3), (2) potassium dichromate reduced with orange juice (cr(III)-OJ); and (3) potassium dichromate [Cr(VI)]. Blood and urine chromium levels were followed for 1-3 days prior to and up to 12 days after ingestion. The three mixtures showed quite different pharmacokinetic patterns. CrCl3 was poorly absorbed (estimated 0.13% bioavailability) and rapidly eliminated in urine (excretion half-life, approximately 10 hr), whereas Cr(III)-OJ was absorbed more efficiently (0.60% bioavailability) but more slowly (half-life, approximately 17 hr), and Cr(VI) had the highest bioavailability (6.9%) and the longest half-life (approximately 39 hr). All three chromium mixtures caused temporary elevations in red blood cell (RBC) and plasma chromium concentrations, but the magnitude and duration of elevation showed a clear trend (Cr(VI) &gt; Cr(III)-OJ &gt; CrCl3). The data suggest that nearly all the ingested Cr(VI) was reduced to Cr(III) before entering the bloodstream based on comparison to RBC and plasma chromium patterns in animals exposed to high doses of Cr(VI). These findings support our prior work which suggests that water-soluble organic complexes of Cr(III) formed during the reduction of Cr(VI) in vivo explain the patterns of blood uptake and urinary excretion in humans at drinking water concentrations of 10 mg/liter or less."
82706,Rusznak et al. 1996,Ozone-induced mediator release from human bronchial epithelial cells in vitro and the influence of nedocromil sodium,"National Asthma Campaing (UK); Joint Research Board of St. Bartholomew's Hospital, London (UK); Fison plc (Loughboroguh, UK).#Although animal and human studies have demonstrated that ozone inhalation leads to airway epithelial inflammation and damage, the underlying mechanisms are not fully understood. We cultured human bronchial epithelial cells as explant cultures and investigated the effect of 6 h of exposure to 0-500 parts per billion (ppb) O3 with or without 10(-5) M nedocromil sodium on: 1) epithelial cell membrane integrity; and 2) release of inflammatory cytokines and soluble intercellular adhesion molecule-1 (sICAM-1), as assessed by enzyme-linked immunosorbent assay (ELISA). O3 exposure led to significant epithelial cell damage at concentrations of 10-500 ppb O3, as indicated by increased release of [51Cr]-labelled sodium chromate. At concentrations of 10-100 ppb, O3 induced maximal release of interleukin-8 (IL-8), granulocyte/macrophage colony-stimulating factor (GM-CSF), tumour necrosis factor-alpha (TNF-alpha) and sICAM-1. The IL-8 and GM-CSF release increased significantly from 5.64+/-0.58 and 0.04+/-0.03 pg x microg(-1) cellular protein, respectively, from control cells exposed to air, to 20.16+/-2.56 and 0.20+/-0.04 pg x microg(-1) cellular protein, respectively, from cells exposed to 50 ppb O3. 10(-5) M nedocromil sodium significantly attenuated the O3-induced release of both IL-8 and GM-CSF (p<0.01). The TNF-alpha and sICAM-1 increases after exposure to 10-50 ppb O3, were also abrogated by treatment of the cells with 10(-5) M nedocromil sodium (p<0.05). Similarly, the antioxidant, glutathione, at concentrations of 400-600 microM, significantly reduced the O3-induced release of IL-8 (p<0.05). In conclusion, these studies indicate that ambient concentrations of ozone may induce airway inflammation, through release of proinflammatory mediators from airway epithelial cells. This effect may be inhibited both by the anti-inflammatory drug, nedocromil sodium, and the naturally occurring antioxidant glutathione.","Ozone-induced mediator release from human bronchial epithelial cells in vitro and the influence of nedocromil sodium Abs: National Asthma Campaing (UK); Joint Research Board of St. Bartholomew's Hospital, London (UK); Fison plc (Loughboroguh, UK).#Although animal and human studies have demonstrated that ozone inhalation leads to airway epithelial inflammation and damage, the underlying mechanisms are not fully understood. We cultured human bronchial epithelial cells as explant cultures and investigated the effect of 6 h of exposure to 0-500 parts per billion (ppb) O3 with or without 10(-5) M nedocromil sodium on: 1) epithelial cell membrane integrity; and 2) release of inflammatory cytokines and soluble intercellular adhesion molecule-1 (sICAM-1), as assessed by enzyme-linked immunosorbent assay (ELISA). O3 exposure led to significant epithelial cell damage at concentrations of 10-500 ppb O3, as indicated by increased release of [51Cr]-labelled sodium chromate. At concentrations of 10-100 ppb, O3 induced maximal release of interleukin-8 (IL-8), granulocyte/macrophage colony-stimulating factor (GM-CSF), tumour necrosis factor-alpha (TNF-alpha) and sICAM-1. The IL-8 and GM-CSF release increased significantly from 5.64+/-0.58 and 0.04+/-0.03 pg x microg(-1) cellular protein, respectively, from control cells exposed to air, to 20.16+/-2.56 and 0.20+/-0.04 pg x microg(-1) cellular protein, respectively, from cells exposed to 50 ppb O3. 10(-5) M nedocromil sodium significantly attenuated the O3-induced release of both IL-8 and GM-CSF (p<0.01). The TNF-alpha and sICAM-1 increases after exposure to 10-50 ppb O3, were also abrogated by treatment of the cells with 10(-5) M nedocromil sodium (p<0.05). Similarly, the antioxidant, glutathione, at concentrations of 400-600 microM, significantly reduced the O3-induced release of IL-8 (p<0.05). In conclusion, these studies indicate that ambient concentrations of ozone may induce airway inflammation, through release of proinflammatory mediators from airway epithelial cells. This effect may be inhibited both by the anti-inflammatory drug, nedocromil sodium, and the naturally occurring antioxidant glutathione."
82435,Nelson et al. 2001,Workplace protection factors--supplied air hood,"Several organizations list assigned protection factors. For supplied air hoods, the value of the assigned protection factors varies from <10 to 2,000 depending on the organization. Workplace protection factors (WPFs) of a supplied air hood were measured during aircraft sanding and painting operations on several types of aircraft to evaluate whether the American National Standard Z88.2 (1992) assigned protection factor of 1,000 was realistic. The primary contaminant during these activities is strontium chromate. Samples collected inside the hood show that employees during sanding and painting operations were not exposed to strontium. The respirator performed adequately. This study is consistent with other simulated and WPF studies in that the ANSI Z88.2 WPF of 1,000 is supported.","Workplace protection factors--supplied air hood Abs: Several organizations list assigned protection factors. For supplied air hoods, the value of the assigned protection factors varies from <10 to 2,000 depending on the organization. Workplace protection factors (WPFs) of a supplied air hood were measured during aircraft sanding and painting operations on several types of aircraft to evaluate whether the American National Standard Z88.2 (1992) assigned protection factor of 1,000 was realistic. The primary contaminant during these activities is strontium chromate. Samples collected inside the hood show that employees during sanding and painting operations were not exposed to strontium. The respirator performed adequately. This study is consistent with other simulated and WPF studies in that the ANSI Z88.2 WPF of 1,000 is supported."
82431,Wise JP et al. 2002,The cytotoxicity and genotoxicity of particulate and soluble hexavalent chromium in human lung cells,"#Hexavalent chromium (Cr(VI)) is a human lung carcinogen. Cr(VI) is a particularly important and dangerous carcinogen, because there is widespread exposure to it both occupationally and to the general public. However, despite the potential for widespread exposure and the fact that the lung is its target organ, there are few reports of the genotoxicity of Cr(VI) in human lung cells. Clearly, in order to better understand this carcinogen, its effects in its target cells need to be evaluated. Accordingly, we determined the cytotoxicity and clastogenicity of both particulate (water-insoluble) and soluble Cr(VI) in primary human bronchial fibroblasts (PHBFs). We used lead chromate (PbCrO(4)) and sodium chromate (Na(2)CrO(4)) as prototypical particulate and soluble Cr(VI) salts, respectively. Both compounds induced concentration-dependent cytotoxicity after a 24h exposure in PHBFs. The relative survival was 87, 46, 26 and 2% after exposure to 0.1, 0.5, 1 and 5 microg/cm(2) PbCrO(4), respectively, and 74, 57, 13 and 0% after exposure to 1, 2.5, 5 and 10 microM Na(2)CrO(4), respectively. Similarly, the amount of chromosome damage increased with concentration after 24h exposure to both compounds. Specifically, 0.1, 0.5 and 1 microg/cm(2) PbCrO(4) damaged 15, 34 and 42% of metaphase cells with the total amount of damage reaching 18, 40 and 66 aberrations per 100 metaphases, respectively. PbCrO(4) (5 microg/cm(2)) induced such profound cell cycle delay that no metaphases were found. Na(2)CrO(4) (1 and 2.5 microM) damaged 18 and 33% of metaphase cells with the total amount of damage reaching 19 and 43 aberrations per 100 metaphases, respectively. Na(2)CrO(4) (5 and 10 microM) induced such profound cell cycle delay that no metaphases were found. Overall the data clearly indicate that Cr(VI) compounds are cytotoxic and genotoxic to human lung cells.","The cytotoxicity and genotoxicity of particulate and soluble hexavalent chromium in human lung cells Abs: #Hexavalent chromium (Cr(VI)) is a human lung carcinogen. Cr(VI) is a particularly important and dangerous carcinogen, because there is widespread exposure to it both occupationally and to the general public. However, despite the potential for widespread exposure and the fact that the lung is its target organ, there are few reports of the genotoxicity of Cr(VI) in human lung cells. Clearly, in order to better understand this carcinogen, its effects in its target cells need to be evaluated. Accordingly, we determined the cytotoxicity and clastogenicity of both particulate (water-insoluble) and soluble Cr(VI) in primary human bronchial fibroblasts (PHBFs). We used lead chromate (PbCrO(4)) and sodium chromate (Na(2)CrO(4)) as prototypical particulate and soluble Cr(VI) salts, respectively. Both compounds induced concentration-dependent cytotoxicity after a 24h exposure in PHBFs. The relative survival was 87, 46, 26 and 2% after exposure to 0.1, 0.5, 1 and 5 microg/cm(2) PbCrO(4), respectively, and 74, 57, 13 and 0% after exposure to 1, 2.5, 5 and 10 microM Na(2)CrO(4), respectively. Similarly, the amount of chromosome damage increased with concentration after 24h exposure to both compounds. Specifically, 0.1, 0.5 and 1 microg/cm(2) PbCrO(4) damaged 15, 34 and 42% of metaphase cells with the total amount of damage reaching 18, 40 and 66 aberrations per 100 metaphases, respectively. PbCrO(4) (5 microg/cm(2)) induced such profound cell cycle delay that no metaphases were found. Na(2)CrO(4) (1 and 2.5 microM) damaged 18 and 33% of metaphase cells with the total amount of damage reaching 19 and 43 aberrations per 100 metaphases, respectively. Na(2)CrO(4) (5 and 10 microM) induced such profound cell cycle delay that no metaphases were found. Overall the data clearly indicate that Cr(VI) compounds are cytotoxic and genotoxic to human lung cells."
82427,Hayes 1997,The carcinogenicity of metals in humans,"Epidemiologic evidence on the relation between exposure to metals and cancer is reviewed. Human exposure to metals is common, with wide use in industry and long-term environmental persistence. Historically, the heaviest metal exposures occurred in the workplace or in environmental settings in close proximity to industrial sources. Among the general population, exposure to a number of metals is widespread but generally at substantially lower levels than have been found in industry. The carcinogenicity of arsenic, chromium, and nickel has been established. Occupational and environmental arsenic exposure is linked to increased lung cancer risk in humans, although experimental studies remain inconclusive. Experimental studies clearly demonstrate the malignant potential of hexavalent(VI) chromium compounds, with solubility being an important determining factor. Epidemiologic studies of workers in chromium chemical production and use link exposure to lung and nasal cancer. Experimental and epidemiologic data show that sparingly-soluble nickel compounds and possibly also the soluble compounds are carcinogens linked to lung and nasal cancer in humans. Some experimental and epidemiologic studies suggest that lead may be a human carcinogen, but the evidence is inconclusive. Although epidemiologic data are less extensive for beryllium and cadmium, the findings in humans of excess cancer risk are supported by the clear demonstration of carcinogenicity in experimental studies. Other metals, including antimony and cobalt, may be human carcinogens, but the experimental and epidemiologic data are limited.","The carcinogenicity of metals in humans Abs: Epidemiologic evidence on the relation between exposure to metals and cancer is reviewed. Human exposure to metals is common, with wide use in industry and long-term environmental persistence. Historically, the heaviest metal exposures occurred in the workplace or in environmental settings in close proximity to industrial sources. Among the general population, exposure to a number of metals is widespread but generally at substantially lower levels than have been found in industry. The carcinogenicity of arsenic, chromium, and nickel has been established. Occupational and environmental arsenic exposure is linked to increased lung cancer risk in humans, although experimental studies remain inconclusive. Experimental studies clearly demonstrate the malignant potential of hexavalent(VI) chromium compounds, with solubility being an important determining factor. Epidemiologic studies of workers in chromium chemical production and use link exposure to lung and nasal cancer. Experimental and epidemiologic data show that sparingly-soluble nickel compounds and possibly also the soluble compounds are carcinogens linked to lung and nasal cancer in humans. Some experimental and epidemiologic studies suggest that lead may be a human carcinogen, but the evidence is inconclusive. Although epidemiologic data are less extensive for beryllium and cadmium, the findings in humans of excess cancer risk are supported by the clear demonstration of carcinogenicity in experimental studies. Other metals, including antimony and cobalt, may be human carcinogens, but the experimental and epidemiologic data are limited."
82383,Connor and  Pier 1990,Reduction of the mutagenicity of lead chromate-based pigments by encapsulation with silica,"13 lead chromate-based pigments were assayed for mutagenicity and toxicity using Salmonella typhimurium TA100. The compounds were assayed with and without S9, both in the presence and absence of the chelating agent, nitrilotriacetic acid (NTA). In general, the use of NTA to solubilize the compounds resulted in mutagenicity and/or toxicity being observed where it had not in the absence of NTA, or being observed at lower concentrations than when water alone was used. Encapsulation of pigments with amorphous silica rendered these pigments non-mutagenic and non-toxic, indicating that the active moieties were biologically unavailable to the bacteria. Varying the percentage of silica encapsulation on one pigment, medium chrome yellow, indicated that 5% encapsulation did not alter the mutagenicity while 10% encapsulation inhibited the mutagenicity without or with NTA.","Reduction of the mutagenicity of lead chromate-based pigments by encapsulation with silica Abs: 13 lead chromate-based pigments were assayed for mutagenicity and toxicity using Salmonella typhimurium TA100. The compounds were assayed with and without S9, both in the presence and absence of the chelating agent, nitrilotriacetic acid (NTA). In general, the use of NTA to solubilize the compounds resulted in mutagenicity and/or toxicity being observed where it had not in the absence of NTA, or being observed at lower concentrations than when water alone was used. Encapsulation of pigments with amorphous silica rendered these pigments non-mutagenic and non-toxic, indicating that the active moieties were biologically unavailable to the bacteria. Varying the percentage of silica encapsulation on one pigment, medium chrome yellow, indicated that 5% encapsulation did not alter the mutagenicity while 10% encapsulation inhibited the mutagenicity without or with NTA."
82360,Costa et al. 1996,Interlaboratory validation of a new assay for DNA-protein crosslinks,"In 1992, a simple and sensitive assay for detecting DNA-protein crosslinks was developed [1]. In an effort to facilitate the greater use of the assay, a number of studies were conducted to evaluate its reliability and reproducibility. During this work, the assay was used to assess whether various metals and other compounds could induce crosslinks in cultured human lymphocytes (Epstein-Barr virus-transformed Burkitt's Lymphoma cell line). Potassium permanganate, mercury chloride, lead nitrate, magnesium perchlorate, aluminum chloride, and cadmium chloride did not induce DNA-protein crosslinks at either cytotoxic or non-cytotoxic levels. Copper sulfate, arsenic trioxide, and potassium chromate induced DNA-protein crosslinks only at cytotoxic concentrations. Acute lethality of the cells was assessed immediately after exposure to metals by trypan blue exclusion while long-term lethality was assessed by cell proliferation and trypan blue exclusion following an incubation period of 5 days after exposure to the metal compound. All metals exhibited more toxicity in the long-term lethality assay compared to the short-term assay. The cultured human lymphocytes treated with various doses of lead acetate, cadmium chloride, arsenic trioxide and copper sulfate, as well as cis-platinum and chromate, were sent to four different laboratories to compare the reliability and reproducibility of the DNA-protein crosslink assay. Depending on the chemical studied, there were quantitative differences in the results observed among the various laboratories using the assay. However, all laboratories generally showed that cis-platinum, chromate, arsenic trioxide and copper sulfate induced DNA-protein crosslinks at levels that produced acute cytotoxicity, whereas cadmium chloride and lead acetate did not.","Interlaboratory validation of a new assay for DNA-protein crosslinks Abs: In 1992, a simple and sensitive assay for detecting DNA-protein crosslinks was developed [1]. In an effort to facilitate the greater use of the assay, a number of studies were conducted to evaluate its reliability and reproducibility. During this work, the assay was used to assess whether various metals and other compounds could induce crosslinks in cultured human lymphocytes (Epstein-Barr virus-transformed Burkitt's Lymphoma cell line). Potassium permanganate, mercury chloride, lead nitrate, magnesium perchlorate, aluminum chloride, and cadmium chloride did not induce DNA-protein crosslinks at either cytotoxic or non-cytotoxic levels. Copper sulfate, arsenic trioxide, and potassium chromate induced DNA-protein crosslinks only at cytotoxic concentrations. Acute lethality of the cells was assessed immediately after exposure to metals by trypan blue exclusion while long-term lethality was assessed by cell proliferation and trypan blue exclusion following an incubation period of 5 days after exposure to the metal compound. All metals exhibited more toxicity in the long-term lethality assay compared to the short-term assay. The cultured human lymphocytes treated with various doses of lead acetate, cadmium chloride, arsenic trioxide and copper sulfate, as well as cis-platinum and chromate, were sent to four different laboratories to compare the reliability and reproducibility of the DNA-protein crosslink assay. Depending on the chemical studied, there were quantitative differences in the results observed among the various laboratories using the assay. However, all laboratories generally showed that cis-platinum, chromate, arsenic trioxide and copper sulfate induced DNA-protein crosslinks at levels that produced acute cytotoxicity, whereas cadmium chloride and lead acetate did not."
82352,Singh et al. 1999,Internalization of carcinogenic lead chromate particles by cultured normal human lung epithelial cells: Formation of intracellular lead-inclusion bodies and induction of apoptosis,"Occupational exposure to certain particulate hexavalent chromium [Cr(VI)] compounds, such as lead chromate, has been associated with lung cancer and respiratory tract toxicity. We have previously shown that apoptosis is a major mode of death in cultured rodent cells treated with soluble sodium chromate and particulate lead chromate. Here we report the cellular and molecular effects of lead chromate and sodium chromate in normal human lung small airway epithelial (HSAE) cells, which may be one of the targets for Cr(VI)-induced lung cancer and respiratory tract toxicity. Phagocytosed lead chromate particles and intracellular lead-inclusion bodies (LIB) were observed by transmission electron microscopy and confirmed by X-ray analysis. HSAE cells exposed to lead chromate and sodium chromate underwent dose-dependent apoptosis. The cellular uptake and genomic interactions of both Cr and lead (Pb) were examined by inductively coupled plasma mass spectrometry (ICPMS) coupled with a novel, direct-injection high-efficiency nebulizer (DIHEN). Using this approach, we have quantitated a dose-dependent formation of Cr-DNA adducts and DNA-associated Pb in lead chromate-treated HSAE cells. The formation of LIB in normal human lung cells exposed to lead chromate indicates that ionic Pb is released from the particles and thus might contribute to the cell toxicity caused by lead chromate. Internalization and dissolution of lead chromate particles and the interaction of ionic Cr and Pb with DNA, may be components of the mechanism of lead chromate carcinogenesis. Lead chromate-induced apoptosis may be a mechanism to eliminate cells with chromium- and/or lead-damaged DNA.","Internalization of carcinogenic lead chromate particles by cultured normal human lung epithelial cells: Formation of intracellular lead-inclusion bodies and induction of apoptosis Abs: Occupational exposure to certain particulate hexavalent chromium [Cr(VI)] compounds, such as lead chromate, has been associated with lung cancer and respiratory tract toxicity. We have previously shown that apoptosis is a major mode of death in cultured rodent cells treated with soluble sodium chromate and particulate lead chromate. Here we report the cellular and molecular effects of lead chromate and sodium chromate in normal human lung small airway epithelial (HSAE) cells, which may be one of the targets for Cr(VI)-induced lung cancer and respiratory tract toxicity. Phagocytosed lead chromate particles and intracellular lead-inclusion bodies (LIB) were observed by transmission electron microscopy and confirmed by X-ray analysis. HSAE cells exposed to lead chromate and sodium chromate underwent dose-dependent apoptosis. The cellular uptake and genomic interactions of both Cr and lead (Pb) were examined by inductively coupled plasma mass spectrometry (ICPMS) coupled with a novel, direct-injection high-efficiency nebulizer (DIHEN). Using this approach, we have quantitated a dose-dependent formation of Cr-DNA adducts and DNA-associated Pb in lead chromate-treated HSAE cells. The formation of LIB in normal human lung cells exposed to lead chromate indicates that ionic Pb is released from the particles and thus might contribute to the cell toxicity caused by lead chromate. Internalization and dissolution of lead chromate particles and the interaction of ionic Cr and Pb with DNA, may be components of the mechanism of lead chromate carcinogenesis. Lead chromate-induced apoptosis may be a mechanism to eliminate cells with chromium- and/or lead-damaged DNA."
82088,Fu and  Boffetta 1995,Cancer and occupational exposure to inorganic lead compounds: a meta-analysis of published data,"OBJECTIVES--To review and summarise the epidemiological evidence on the carcinogenicity of occupational exposure to inorganic lead. METHODS--Case-control and cohort studies were reviewed and combined for meta-analysis. Fixed and random effect methods were used to estimate the summary effects. RESULTS--The combined results show a significant excess risk of overall cancer, stomach cancer, lung cancer, and bladder cancer, with relative risk ratios (RRs) and 95% confidence intervals (95% CIs) in the meta-analysis of 1.11 (1.05-1.17), 1.33 (1.18-1.49), 1.29 (1.10-1.50), and 1.41 (1.16-1.71) respectively. The RR (95% CI) for kidney cancer was also high, but did not reach significance (1.19 (0.96-1.48)). A separate analysis of studies of heavily exposed workers provided slightly increased RRs for cancers of the stomach (1.50) and lung (1.42). CONCLUSIONS--The findings from the workers with heavy exposure to lead provided some evidence to support the hypothesis of an association between stomach and lung cancer and exposure to lead. The main limitation of the present analysis is that the excess risks do not take account of potential confounders, because little information was available for other occupational exposures, smoking, and dietary habits. To some extent, the risk of lung cancer might be explained by confounders such as tobacco smoking and exposure to other occupational carcinogens. The excess risk of stomach cancer may also be explained, at least in part, by non-occupational factors. For bladder and kidney cancers, the excess risks are only suggestive of a true effect because of possible publication bias.","Cancer and occupational exposure to inorganic lead compounds: a meta-analysis of published data Abs: OBJECTIVES--To review and summarise the epidemiological evidence on the carcinogenicity of occupational exposure to inorganic lead. METHODS--Case-control and cohort studies were reviewed and combined for meta-analysis. Fixed and random effect methods were used to estimate the summary effects. RESULTS--The combined results show a significant excess risk of overall cancer, stomach cancer, lung cancer, and bladder cancer, with relative risk ratios (RRs) and 95% confidence intervals (95% CIs) in the meta-analysis of 1.11 (1.05-1.17), 1.33 (1.18-1.49), 1.29 (1.10-1.50), and 1.41 (1.16-1.71) respectively. The RR (95% CI) for kidney cancer was also high, but did not reach significance (1.19 (0.96-1.48)). A separate analysis of studies of heavily exposed workers provided slightly increased RRs for cancers of the stomach (1.50) and lung (1.42). CONCLUSIONS--The findings from the workers with heavy exposure to lead provided some evidence to support the hypothesis of an association between stomach and lung cancer and exposure to lead. The main limitation of the present analysis is that the excess risks do not take account of potential confounders, because little information was available for other occupational exposures, smoking, and dietary habits. To some extent, the risk of lung cancer might be explained by confounders such as tobacco smoking and exposure to other occupational carcinogens. The excess risk of stomach cancer may also be explained, at least in part, by non-occupational factors. For bladder and kidney cancers, the excess risks are only suggestive of a true effect because of possible publication bias."
81968,Xie et al. 2005,Carcinogenic lead chromate induces DNA double-strand breaks in human lung cells,"#Hexavalent chromium (Cr(VI)) is a widespread environmental contaminant and a known human carcinogen, generally causing bronchial cancer. Recent studies have shown that the particulate forms of Cr(VI) are the potent carcinogens. Particulate Cr(VI) is known to induce a spectrum of DNA damage such as DNA single strand breaks, Cr-DNA adducts, DNA-protein crosslinks and chromosomal aberrations. However, particulate Cr(VI)-induced DNA double strand breaks (DSBs) have not been reported. Thus, the aim of this study was to determine if particulate Cr(VI)-induces DSBs in human bronchial cells. Using the single cell gel electrophoresis assay (comet assay), showed that lead chromate-induced concentration dependent increases in DSBs with 0.1, 0.5, 1 and 5mug/cm(2) lead chromate inducing a 20, 50, 67 and 109% relative increase in the tail integrated intensity ratio, respectively. Sodium chromate at concentrations of 1, 2.5 and 5muM induced 38, 78 and 107% relative increase in the tail integrated intensity ratio, respectively. We also show that genotoxic concentrations of lead chromate activate the ataxia telangiectasia mutated (ATM) protein, which is thought to play a central role in the early stages of DSB detection and controls cellular responses to this damage. The H2A.X protein becomes rapidly phosphorylated on residue serine 139 in cells when DSBs are introduced into the DNA by ionizing radiation. By using immunofluorescence, we found that lead chromate-induced concentration-dependent increases in phosphorylated H2A.X (r-H2A.X) foci formation with 0.1, 0.5, 1, 5 and 10mug/cm(2) lead chromate inducing a relative increase in the number of cells with r-H2A.X foci formation of 43, 51, 115 and 129%, respectively.","Carcinogenic lead chromate induces DNA double-strand breaks in human lung cells Abs: #Hexavalent chromium (Cr(VI)) is a widespread environmental contaminant and a known human carcinogen, generally causing bronchial cancer. Recent studies have shown that the particulate forms of Cr(VI) are the potent carcinogens. Particulate Cr(VI) is known to induce a spectrum of DNA damage such as DNA single strand breaks, Cr-DNA adducts, DNA-protein crosslinks and chromosomal aberrations. However, particulate Cr(VI)-induced DNA double strand breaks (DSBs) have not been reported. Thus, the aim of this study was to determine if particulate Cr(VI)-induces DSBs in human bronchial cells. Using the single cell gel electrophoresis assay (comet assay), showed that lead chromate-induced concentration dependent increases in DSBs with 0.1, 0.5, 1 and 5mug/cm(2) lead chromate inducing a 20, 50, 67 and 109% relative increase in the tail integrated intensity ratio, respectively. Sodium chromate at concentrations of 1, 2.5 and 5muM induced 38, 78 and 107% relative increase in the tail integrated intensity ratio, respectively. We also show that genotoxic concentrations of lead chromate activate the ataxia telangiectasia mutated (ATM) protein, which is thought to play a central role in the early stages of DSB detection and controls cellular responses to this damage. The H2A.X protein becomes rapidly phosphorylated on residue serine 139 in cells when DSBs are introduced into the DNA by ionizing radiation. By using immunofluorescence, we found that lead chromate-induced concentration-dependent increases in phosphorylated H2A.X (r-H2A.X) foci formation with 0.1, 0.5, 1, 5 and 10mug/cm(2) lead chromate inducing a relative increase in the number of cells with r-H2A.X foci formation of 43, 51, 115 and 129%, respectively."
81967,Xie et al. 2004,Lead chromate-induced chromosome damage requires extracellular dissolution to liberate chromium ions but does not require particle internalization or intracellular dissolution,"#Hexavalent chromium [Cr(VI)] is a well-established human lung carcinogen. Water solubility has proven to be a key factor in the carcinogenicity of Cr(VI), with the water insoluble or ""particulate"" compounds the more potent carcinogens. Pathology studies indicate that chromates target cells at bronchial bifurcation sites in human lungs. However, it is uncertain what roles particle internalization and dissolution play in the genotoxicity of these compounds to human lung cells. We investigated these mechanisms in a human lung cell line after exposure to particulate lead chromate. We found that lead chromate was clastogenic in a concentration-dependent manner with 0.1, 0.5, and 1 microg/cm(2), while 5 and 10 microg/cm(2) caused complete cell cycle arrest. We also found concentration-dependent increases in intracellular and extracellular chromium ion levels. We investigated particle internalization by using transmission electron microscopy and found an apparent relative increase with concentration but no apparent particle internalization at the lowest concentration (0.1 microg/cm(2)) even after 24 h. Furthermore, we found no lysosomal association with the vacuoles containing particles, further suggesting that intracellular dissolution did not occur. Cotreating the cells with lead chromate and vitamin C eliminated both the uptake of ionic chromium and the clastogenic activity of lead chromate but had no effect on particle internalization. These data indicate that in human bronchial cells lead chromate clastogenesis is mediated by the extracellular dissolution of the particles and not their internalization. These findings have important implications for our understanding of the physicochemical mechanism of particulate chromates as they contradict previous indirect data from human bronchial epithelial cells, which suggest that particles dissolve inside those cells. Thus, these new data suggest that there may be different mechanisms of genotoxicity for epithelial cells and fibroblasts exposed to chromate particles.","Lead chromate-induced chromosome damage requires extracellular dissolution to liberate chromium ions but does not require particle internalization or intracellular dissolution Abs: #Hexavalent chromium [Cr(VI)] is a well-established human lung carcinogen. Water solubility has proven to be a key factor in the carcinogenicity of Cr(VI), with the water insoluble or ""particulate"" compounds the more potent carcinogens. Pathology studies indicate that chromates target cells at bronchial bifurcation sites in human lungs. However, it is uncertain what roles particle internalization and dissolution play in the genotoxicity of these compounds to human lung cells. We investigated these mechanisms in a human lung cell line after exposure to particulate lead chromate. We found that lead chromate was clastogenic in a concentration-dependent manner with 0.1, 0.5, and 1 microg/cm(2), while 5 and 10 microg/cm(2) caused complete cell cycle arrest. We also found concentration-dependent increases in intracellular and extracellular chromium ion levels. We investigated particle internalization by using transmission electron microscopy and found an apparent relative increase with concentration but no apparent particle internalization at the lowest concentration (0.1 microg/cm(2)) even after 24 h. Furthermore, we found no lysosomal association with the vacuoles containing particles, further suggesting that intracellular dissolution did not occur. Cotreating the cells with lead chromate and vitamin C eliminated both the uptake of ionic chromium and the clastogenic activity of lead chromate but had no effect on particle internalization. These data indicate that in human bronchial cells lead chromate clastogenesis is mediated by the extracellular dissolution of the particles and not their internalization. These findings have important implications for our understanding of the physicochemical mechanism of particulate chromates as they contradict previous indirect data from human bronchial epithelial cells, which suggest that particles dissolve inside those cells. Thus, these new data suggest that there may be different mechanisms of genotoxicity for epithelial cells and fibroblasts exposed to chromate particles."
81965,Wise et al. 2004,Chromium is the proximate clastogenic species for lead chromate-induced clastogenicity in human bronchial cells,"#Hexavalent chromium (Cr(VI)) is a well-established human lung carcinogen with potentially widespread exposure. Solubility is a key factor in the carcinogenicity of Cr(VI), with the water-insoluble or 'particulate' compounds being the more potent carcinogens. Studies have indicated that the component ions are responsible for their clastogenicity, but it is uncertain whether chromium (Cr), lead (Pb) or some combination of the two is responsible for the clastogenic effects. Accordingly, we compared the clastogenicity of lead chromate (LC) with soluble sodium chromate (SC) and lead glutamate (LG) in WTHBF-6 human lung cells. We found that 1436microM was the maximal intracellular level of Pb after exposure to clastogenic concentrations of LC. However, clastogenesis was not observed after exposure to LG, even when intracellular Pb concentrations reached 13,347microM, indicating that intracellular Pb levels did not reach clastogenic levels in WTHBF-6 cells after LC treatment. By contrast, SC was clastogenic damaging 16 and 44% of metaphase cells at intracellular Cr doses of 312 and 1262microM respectively, which was comparable to the clastogenesis observed after LC treatment. LC damaged 10, 27 and 37% of metaphases at intracellular Cr doses of 288, 926 and 1644microM, respectively. These data indicate that with respect to LC-induced clastogenicity, Cr and not Pb is the proximate clastogenic species in human lung cells.","Chromium is the proximate clastogenic species for lead chromate-induced clastogenicity in human bronchial cells Abs: #Hexavalent chromium (Cr(VI)) is a well-established human lung carcinogen with potentially widespread exposure. Solubility is a key factor in the carcinogenicity of Cr(VI), with the water-insoluble or 'particulate' compounds being the more potent carcinogens. Studies have indicated that the component ions are responsible for their clastogenicity, but it is uncertain whether chromium (Cr), lead (Pb) or some combination of the two is responsible for the clastogenic effects. Accordingly, we compared the clastogenicity of lead chromate (LC) with soluble sodium chromate (SC) and lead glutamate (LG) in WTHBF-6 human lung cells. We found that 1436microM was the maximal intracellular level of Pb after exposure to clastogenic concentrations of LC. However, clastogenesis was not observed after exposure to LG, even when intracellular Pb concentrations reached 13,347microM, indicating that intracellular Pb levels did not reach clastogenic levels in WTHBF-6 cells after LC treatment. By contrast, SC was clastogenic damaging 16 and 44% of metaphase cells at intracellular Cr doses of 312 and 1262microM respectively, which was comparable to the clastogenesis observed after LC treatment. LC damaged 10, 27 and 37% of metaphases at intracellular Cr doses of 288, 926 and 1644microM, respectively. These data indicate that with respect to LC-induced clastogenicity, Cr and not Pb is the proximate clastogenic species in human lung cells."
81962,Wedrychowski et al. 1986,The in vivo cross-linking of proteins and DNA by heavy metals,"Cross-linking of proteins to DNA in live, intact Novikoff ascites hepatoma cells exposed in vitro to different concentrations of CuSO4, Pb(NO3)2, HgCl2, and AlCl3 was studied. Protein-DNA complexes were separated by high-speed centrifugation of cells solubilized in buffered 4% sodium dodecyl sulfate and assayed by electrophoretic separation of proteins associated with the DNA-containing pellets. Concentration dependence experiments showed that the optimal cross-linking occurred at metal concentration of 0.5 mM for CuSO4, HgCl2, and AlCl3 while the optimal cross-linking for Pb(NO3)2 was at 5 mM. For some metals at concentrations higher than optimal, the amounts of cross-linked proteins decreased significantly. Immunochemical analysis of the cross-linked proteins using antibodies to matrix, chromatin, lamins, and cytokeratin fractions demonstrated that some, but not all, members of these protein families became cross-linked to the DNA. Each metal exhibited a cross-linking pattern of its own, different from those of the other metals. Radioactive labeling experiments showed that all the metals tested became associated with the DNA-protein pellets within 1 h after their addition to the incubation medium. However, hexavalent chromium required more than 2 h before appearing in the DNA-protein pellets in significant amounts.","The in vivo cross-linking of proteins and DNA by heavy metals Abs: Cross-linking of proteins to DNA in live, intact Novikoff ascites hepatoma cells exposed in vitro to different concentrations of CuSO4, Pb(NO3)2, HgCl2, and AlCl3 was studied. Protein-DNA complexes were separated by high-speed centrifugation of cells solubilized in buffered 4% sodium dodecyl sulfate and assayed by electrophoretic separation of proteins associated with the DNA-containing pellets. Concentration dependence experiments showed that the optimal cross-linking occurred at metal concentration of 0.5 mM for CuSO4, HgCl2, and AlCl3 while the optimal cross-linking for Pb(NO3)2 was at 5 mM. For some metals at concentrations higher than optimal, the amounts of cross-linked proteins decreased significantly. Immunochemical analysis of the cross-linked proteins using antibodies to matrix, chromatin, lamins, and cytokeratin fractions demonstrated that some, but not all, members of these protein families became cross-linked to the DNA. Each metal exhibited a cross-linking pattern of its own, different from those of the other metals. Radioactive labeling experiments showed that all the metals tested became associated with the DNA-protein pellets within 1 h after their addition to the incubation medium. However, hexavalent chromium required more than 2 h before appearing in the DNA-protein pellets in significant amounts."
81941,Schechtman et al. 1986,Analysis of the interlaboratory and intralaboratory reproducibility of the enhancement of simian adenovirus SA7 transformation of Syrian hamster embryo cells by model carcinogenic and noncarcinogenic compounds,"#The intralaboratory and interlaboratory reproducibility of a DNA virus (SA7) transformation enhancement assay was investigated using nine carcinogenic and noncarcinogenic compounds representing a variety of chemical classes. By the use of standardized procedures designed to limit assay variables, replicate assay data were collected in two independent laboratories and analyzed for concurrence. The carcinogens, 7,12-dimethylbenz(a)anthracene, benzo(a)pyrene, and N-methyl-N'-nitro-N-nitrosoguanidine yielded reproducible dose-dependent cytotoxicity and positive transformation effects (defined as statistically significant [p less than or equal to 0.05] enhancement of virus transformation at two or more consecutive dose levels) in all experiments in both laboratories. The carcinogens lead chromate, diethylnitrosamine, 4-nitroquinoline-N-oxide, and 2-acetylaminofluorene demonstrated enhancement of SA7 transformation at two or more dose levels in 40-50% of the assays. The noncarcinogenic structural analogs anthracene and pyrene consistently did not produce positive assay responses when tested at dose levels up to the limits of solubility. Good interlaboratory concurrence was demonstrated for these model compounds in the Syrian hamster embryo cell-SA7 assay.","Analysis of the interlaboratory and intralaboratory reproducibility of the enhancement of simian adenovirus SA7 transformation of Syrian hamster embryo cells by model carcinogenic and noncarcinogenic compounds Abs: #The intralaboratory and interlaboratory reproducibility of a DNA virus (SA7) transformation enhancement assay was investigated using nine carcinogenic and noncarcinogenic compounds representing a variety of chemical classes. By the use of standardized procedures designed to limit assay variables, replicate assay data were collected in two independent laboratories and analyzed for concurrence. The carcinogens, 7,12-dimethylbenz(a)anthracene, benzo(a)pyrene, and N-methyl-N'-nitro-N-nitrosoguanidine yielded reproducible dose-dependent cytotoxicity and positive transformation effects (defined as statistically significant [p less than or equal to 0.05] enhancement of virus transformation at two or more consecutive dose levels) in all experiments in both laboratories. The carcinogens lead chromate, diethylnitrosamine, 4-nitroquinoline-N-oxide, and 2-acetylaminofluorene demonstrated enhancement of SA7 transformation at two or more dose levels in 40-50% of the assays. The noncarcinogenic structural analogs anthracene and pyrene consistently did not produce positive assay responses when tested at dose levels up to the limits of solubility. Good interlaboratory concurrence was demonstrated for these model compounds in the Syrian hamster embryo cell-SA7 assay."
81934,Patierno and  Landolph 1989,Soluble vs insoluble hexavalent chromate Relationship of mutation to in vitro transformation and particle uptake,"#Soluble CaCrO4 and insoluble PbCrO4 were tested for induction of mutation to 6-thioguanine (base-substitution, deletion, addition, and frameshift mutations) or ouabain (base-substitution mutations) resistance in Chinese hamster ovary cells and morphological transformation in C3H/10(1/2) mouse embryo cells. CaCrO4 induced dose-dependent cytotoxicity and mutation to 6-thioguanine resistance, but did not induce mutation to ouabain resistance or morphological transformation. Highly cytotoxic amounts of CaCrO4 induced conversion of 10T1/2 cells to adipocytes, but cell lines derived from such cells were not transformed. PbCrO4 was not mutagenic in either mutation assay but induced a dose-dependent, low frequency of focus formation. Cell lines established from these foci had a 3-5-fold increased saturation density, grew in soft agarose, and were tumorigenic in nude mice. Chronic exposure to CaCrO4 or PbCl2 did not induce transformation, PbCl2 was inactive even at acutely cytotoxic concentrations, and sequential treatments with CaCrO4 and PbCl2 did not induce transformation. Light and scanning electron microscopy showed progressive cytoplasmic engulfment of PbCrO4 particles and extensive vacuolization of cells in contact with the particles. No particles were observed inside of vacuoles. We suggest that internalization of PbCrO4 and the associated cellular stress response may be related to PbCrO4-induced neoplastic transformation of 10T1/2 cells.","Soluble vs insoluble hexavalent chromate Relationship of mutation to in vitro transformation and particle uptake Abs: #Soluble CaCrO4 and insoluble PbCrO4 were tested for induction of mutation to 6-thioguanine (base-substitution, deletion, addition, and frameshift mutations) or ouabain (base-substitution mutations) resistance in Chinese hamster ovary cells and morphological transformation in C3H/10(1/2) mouse embryo cells. CaCrO4 induced dose-dependent cytotoxicity and mutation to 6-thioguanine resistance, but did not induce mutation to ouabain resistance or morphological transformation. Highly cytotoxic amounts of CaCrO4 induced conversion of 10T1/2 cells to adipocytes, but cell lines derived from such cells were not transformed. PbCrO4 was not mutagenic in either mutation assay but induced a dose-dependent, low frequency of focus formation. Cell lines established from these foci had a 3-5-fold increased saturation density, grew in soft agarose, and were tumorigenic in nude mice. Chronic exposure to CaCrO4 or PbCl2 did not induce transformation, PbCl2 was inactive even at acutely cytotoxic concentrations, and sequential treatments with CaCrO4 and PbCl2 did not induce transformation. Light and scanning electron microscopy showed progressive cytoplasmic engulfment of PbCrO4 particles and extensive vacuolization of cells in contact with the particles. No particles were observed inside of vacuoles. We suggest that internalization of PbCrO4 and the associated cellular stress response may be related to PbCrO4-induced neoplastic transformation of 10T1/2 cells."
81906,Elias et al. 1989,Cytotoxic and neoplastic transforming effects of industrial hexavalent chromium pigments in Syrian hamster embryo cells,"Twenty eight moderately water-soluble to insoluble chromium (VI) compounds, such as zinc and lead chromate, industrial and laboratory synthesized pigments, and the analytical reagents strontium, barium and calcium chromate, were physicochemically characterized and studied for cytotoxicity and morphological transformation in cultured Syrian hamster embryo (SHE) cells. In vivo validation of malignancy of transformed SHE cells was performed. A high physicochemical diversity among the complex chromium pigments was revealed. The solubility of the compounds was greatly increased after incubation in a complete medium and even higher under cell culture conditions. The cytotoxic effects appeared to be due principally to extracellular solubilized chromium because the most solubilized compounds. Zn, Ca and Sr chromates, were equitoxic at about the same Cr concentration treatment and 8-fold more cytotoxic than less soluble compounds such as some Pb chromates and Ba chromate. However, certain physicochemical properties of lead chromate pigments could also influence their cytotoxic activity. All test compounds were, in a dose-dependent manner, efficient in inducing morphological transformation of SHE cells. Many of the Cr pigments, although physicochemically different, were similarly effective in transformation induction. Nevertheless, compounds among Zn and Pb chromates had various transforming potencies. Ba chromate was the least active in inducing transformation. Certain physicochemical properties could mediate the transforming activity but no particular relationship could be established between any one of the physicochemical parameters and the transforming potency. Cloned morphologically-transformed colonies of SHE cells were grown in soft agar medium and showed true neoplastic behaviour by tumour formation in syngeneic animals. These results show that various chromate pigments containing either Zn or Pb, of medium to very low aqueous solubility, induced neoplastic transformation of SHE cells.","Cytotoxic and neoplastic transforming effects of industrial hexavalent chromium pigments in Syrian hamster embryo cells Abs: Twenty eight moderately water-soluble to insoluble chromium (VI) compounds, such as zinc and lead chromate, industrial and laboratory synthesized pigments, and the analytical reagents strontium, barium and calcium chromate, were physicochemically characterized and studied for cytotoxicity and morphological transformation in cultured Syrian hamster embryo (SHE) cells. In vivo validation of malignancy of transformed SHE cells was performed. A high physicochemical diversity among the complex chromium pigments was revealed. The solubility of the compounds was greatly increased after incubation in a complete medium and even higher under cell culture conditions. The cytotoxic effects appeared to be due principally to extracellular solubilized chromium because the most solubilized compounds. Zn, Ca and Sr chromates, were equitoxic at about the same Cr concentration treatment and 8-fold more cytotoxic than less soluble compounds such as some Pb chromates and Ba chromate. However, certain physicochemical properties of lead chromate pigments could also influence their cytotoxic activity. All test compounds were, in a dose-dependent manner, efficient in inducing morphological transformation of SHE cells. Many of the Cr pigments, although physicochemically different, were similarly effective in transformation induction. Nevertheless, compounds among Zn and Pb chromates had various transforming potencies. Ba chromate was the least active in inducing transformation. Certain physicochemical properties could mediate the transforming activity but no particular relationship could be established between any one of the physicochemical parameters and the transforming potency. Cloned morphologically-transformed colonies of SHE cells were grown in soft agar medium and showed true neoplastic behaviour by tumour formation in syngeneic animals. These results show that various chromate pigments containing either Zn or Pb, of medium to very low aqueous solubility, induced neoplastic transformation of SHE cells."
81899,Celotti et al. 1987,Interactions of nitrilotriacetic acid (NTA) with Cr(VI) compounds in the induction of gene mutations in cultured mammalian cells,"We used the V79 Chinese hamster cell line to detect the induction by NTA of 6-thioguanine resistance, due to mutation at the HGPRT locus, with direct and indirect mutagens as positive controls. NTA was tested within the 10(-4)-1.5 X 10(-2) M concentration range: although it was cytotoxic above the 10(-2) M dose, it did not increase the frequency of mutations at any of the tested concentrations, independently of metabolic activation (rat-liver S9 fraction). NTA is known to dissolve heavy metals and therefore to increase their genotoxicity. We found that an insoluble Cr(VI) compound, lead chromate (PbCrO4), was not cytotoxic nor mutagenic on V79 cells, probably because it is taken up by the cells very slowly, whereas the presence of NTA (2.5 X 10(-3) M in water) elicited a direct cytotoxicity and mutagenicity, which was dose-dependent from 5 X 10(-5) M to 10(-4) M PbCrO4. This effect was due to solubilization of the chromate anion by NTA, as determined by comparing spectrophotometric determinations of Cr(VI) in PbCrO4 treatment solutions with a mutagenicity titration curve obtained with a completely soluble Cr(VI) salt (potassium dichromate, K2Cr2O7).","Interactions of nitrilotriacetic acid (NTA) with Cr(VI) compounds in the induction of gene mutations in cultured mammalian cells Abs: We used the V79 Chinese hamster cell line to detect the induction by NTA of 6-thioguanine resistance, due to mutation at the HGPRT locus, with direct and indirect mutagens as positive controls. NTA was tested within the 10(-4)-1.5 X 10(-2) M concentration range: although it was cytotoxic above the 10(-2) M dose, it did not increase the frequency of mutations at any of the tested concentrations, independently of metabolic activation (rat-liver S9 fraction). NTA is known to dissolve heavy metals and therefore to increase their genotoxicity. We found that an insoluble Cr(VI) compound, lead chromate (PbCrO4), was not cytotoxic nor mutagenic on V79 cells, probably because it is taken up by the cells very slowly, whereas the presence of NTA (2.5 X 10(-3) M in water) elicited a direct cytotoxicity and mutagenicity, which was dose-dependent from 5 X 10(-5) M to 10(-4) M PbCrO4. This effect was due to solubilization of the chromate anion by NTA, as determined by comparing spectrophotometric determinations of Cr(VI) in PbCrO4 treatment solutions with a mutagenicity titration curve obtained with a completely soluble Cr(VI) salt (potassium dichromate, K2Cr2O7)."
81897,Biedermann and  Landolph 1990,"Role of valence state and solubility of chromium compounds on induction of cytotoxicity, mutagenesis, and anchorage independence in diploid human fibroblasts","We previously showed that carcinogenic nickel, arsenic, and chromium(VI) compounds induced anchorage independence (AI) in diploid human fibroblastic cells (HFC) derived from foreskins (K. A. Biedermann and J. R. Landolph, Cancer Res., 47: 3815-3823, 1987). To elucidate the role of the valence state of chromium and solubility of chromium compounds in inducing AI, we studied the ability of soluble and insoluble hexavalent [chromium(VI)] and trivalent [chromium(III)] chromium compounds to induce mutation and AI in HFC. Chromium(VI) compounds (PbCrO4, CaCrO4, Na2CrO4, and CrO3) were 1000-fold more cytotoxic to HFC (average 50% lethal dose 0.5 ÁM) than chromium(III) compounds (CrCl3, Cr2O3, Cr2S3; average 50% lethal dose 500 ÁM). However, equal concentrations (0.1û10.0 ÁM) of soluble or insoluble chromium compounds in either +6 or +3 valence states induced similar increases in frequencies of AI in HFC (100û200/105). Chromium(VI)- and chromium(III)-induced AI was a stable phenotype. All soluble chromium(VI) and insoluble chromium(III) compounds studied induced mutation to 6-thioguanine resistance at cytotoxic concentrations in HFC. Insoluble PbCr(VI)O4 and a soluble form of Cr(III)Cl3 were inactive in this assay. Mutation induction by chromium(III) compounds only occurred at cytotoxic concentrations (100-1000 ÁM) 1000-fold greater than those concentrations of chromium(VI) compounds (0.25-1 ÁM) which were cytotoxic, mutagenic, and induced AI. Soluble hexavalent Na251CrO4 was taken up facilely by cells at concentrations that induced cytotoxicity, mutation, and AI. At concentrations of 0.25-1.0 ÁM, which induced AI but were not cytotoxic or mutagenic, or concentrations of 1-1000 ÁM, which were cytotoxic and mutagenic, soluble trivalent 51CrCl3 was not taken up by cells. An insoluble form of CrCl3 was not taken up intracellularly but did avidly associate with cells over the concentration range 1 to 100 ÁM which induced AI, cytotoxicity, and mutagenicity. Therefore, both chromium(VI) and chromium(III) compounds induced genotoxic effects in human fibroblasts. Cellular uptake, cytotoxicity, mutagenicity, and AI induced by soluble chromium(VI) compounds all occurred at the low concentrations of 0.2 to 1.0 ÁM; hence mutagenicity and induction of AI may be coupled for soluble chromium(VI) compounds but not for insoluble PbCrO4, which induced AI but was not mutagenic. Cytotoxicity and mutagenicity of insoluble chromium(III) occurred at concentrations of 10-100 ÁM, but induction of AI occurred at concentrations of 0.1-10 ÁM, indicating that inductions of mutagenicity and AI were not coupled for chromium(III) compounds. We postulate that induction of AI by insoluble PbCr(VI)O4 and by insoluble and soluble Cr(III) compounds occurs by a mechanism not involving base substitution or frameshift mutations. Since there was no significant cellular uptake of Cr(III) compounds, induction of AI by chromium(III) compounds might involve Cr(III)-induced membrane damage, followed by generation of chemically reactive membrane components, which could act intracellularly to induce stable AI.","Role of valence state and solubility of chromium compounds on induction of cytotoxicity, mutagenesis, and anchorage independence in diploid human fibroblasts Abs: We previously showed that carcinogenic nickel, arsenic, and chromium(VI) compounds induced anchorage independence (AI) in diploid human fibroblastic cells (HFC) derived from foreskins (K. A. Biedermann and J. R. Landolph, Cancer Res., 47: 3815-3823, 1987). To elucidate the role of the valence state of chromium and solubility of chromium compounds in inducing AI, we studied the ability of soluble and insoluble hexavalent [chromium(VI)] and trivalent [chromium(III)] chromium compounds to induce mutation and AI in HFC. Chromium(VI) compounds (PbCrO4, CaCrO4, Na2CrO4, and CrO3) were 1000-fold more cytotoxic to HFC (average 50% lethal dose 0.5 ÁM) than chromium(III) compounds (CrCl3, Cr2O3, Cr2S3; average 50% lethal dose 500 ÁM). However, equal concentrations (0.1û10.0 ÁM) of soluble or insoluble chromium compounds in either +6 or +3 valence states induced similar increases in frequencies of AI in HFC (100û200/105). Chromium(VI)- and chromium(III)-induced AI was a stable phenotype. All soluble chromium(VI) and insoluble chromium(III) compounds studied induced mutation to 6-thioguanine resistance at cytotoxic concentrations in HFC. Insoluble PbCr(VI)O4 and a soluble form of Cr(III)Cl3 were inactive in this assay. Mutation induction by chromium(III) compounds only occurred at cytotoxic concentrations (100-1000 ÁM) 1000-fold greater than those concentrations of chromium(VI) compounds (0.25-1 ÁM) which were cytotoxic, mutagenic, and induced AI. Soluble hexavalent Na251CrO4 was taken up facilely by cells at concentrations that induced cytotoxicity, mutation, and AI. At concentrations of 0.25-1.0 ÁM, which induced AI but were not cytotoxic or mutagenic, or concentrations of 1-1000 ÁM, which were cytotoxic and mutagenic, soluble trivalent 51CrCl3 was not taken up by cells. An insoluble form of CrCl3 was not taken up intracellularly but did avidly associate with cells over the concentration range 1 to 100 ÁM which induced AI, cytotoxicity, and mutagenicity. Therefore, both chromium(VI) and chromium(III) compounds induced genotoxic effects in human fibroblasts. Cellular uptake, cytotoxicity, mutagenicity, and AI induced by soluble chromium(VI) compounds all occurred at the low concentrations of 0.2 to 1.0 ÁM; hence mutagenicity and induction of AI may be coupled for soluble chromium(VI) compounds but not for insoluble PbCrO4, which induced AI but was not mutagenic. Cytotoxicity and mutagenicity of insoluble chromium(III) occurred at concentrations of 10-100 ÁM, but induction of AI occurred at concentrations of 0.1-10 ÁM, indicating that inductions of mutagenicity and AI were not coupled for chromium(III) compounds. We postulate that induction of AI by insoluble PbCr(VI)O4 and by insoluble and soluble Cr(III) compounds occurs by a mechanism not involving base substitution or frameshift mutations. Since there was no significant cellular uptake of Cr(III) compounds, induction of AI by chromium(III) compounds might involve Cr(III)-induced membrane damage, followed by generation of chemically reactive membrane components, which could act intracellularly to induce stable AI."
81896,Biedermann and  Landolph 1987,Induction of anchorage independence in human diploid foreskin fibroblasts by carcinogenic metal salts,"We studied whether arsenic, nickel, and chromium compounds that are human carcinogens could induce transformation of cultured primary human diploid foreskin cells (HFC). All nickel compounds tested, PbCrO4, K2Cr2O7, CrO3, Na2HAsO4, NaAsO2, and N-methyl-N'-nitro-N-nitrosoguanidine (MNNG) caused significant (p = 0.001) dose-dependent inductions of anchorage-independent colonies in HFC. KH2AsO4, CaCl2, MnCl2, and Hg(CH3CO2)2 did not induce anchorage independence. Optimal expression times for induction of anchorage independence in HFC were observed as early as 11 days following treatment with MNNG, Ni3S2, Ni(C2H3O2), or NiSO4. Cell strains derived from anchorage-independent colonies showed 33 to 429-fold higher plating efficiencies in soft agar than parental populations, and the anchorage-independent phenotype was stable for eight passages, at which time cells senesced. Anchorage-independent cell strains derived from metal salt-treated cells were not resistant to the cytotoxicity of metal salts, indicating metal salts induced rather than selected for anchorage independence. Nine of 10 cell strains derived from metal compound- or MNNG-induced anchorage-independent colonies displayed the same or lower saturation densities than untreated human fibroblasts. None of these cell strains escaped senescence or showed definitive morphological transformation. MNNG (1 micrograms/ml) induced anchorage independence and mutation to ouabain resistance and 6-thioguanine resistance in HFC, but concentrations of Ni2S3 that induced anchorage independence did not induce mutation at either locus in HFC. These results demonstrate that carcinogenic metal salts induce stable anchorage independence early in human diploid foreskin fibroblasts, and this anchorage independence is independent of other in vitro markers of fibroblast transformation, such as focus formation or immortality. Metal salt induction of anchorage independence can now be used as an assay to study mechanisms of genotoxicity exerted by carcinogenic metal compounds in human cells.","Induction of anchorage independence in human diploid foreskin fibroblasts by carcinogenic metal salts Abs: We studied whether arsenic, nickel, and chromium compounds that are human carcinogens could induce transformation of cultured primary human diploid foreskin cells (HFC). All nickel compounds tested, PbCrO4, K2Cr2O7, CrO3, Na2HAsO4, NaAsO2, and N-methyl-N'-nitro-N-nitrosoguanidine (MNNG) caused significant (p = 0.001) dose-dependent inductions of anchorage-independent colonies in HFC. KH2AsO4, CaCl2, MnCl2, and Hg(CH3CO2)2 did not induce anchorage independence. Optimal expression times for induction of anchorage independence in HFC were observed as early as 11 days following treatment with MNNG, Ni3S2, Ni(C2H3O2), or NiSO4. Cell strains derived from anchorage-independent colonies showed 33 to 429-fold higher plating efficiencies in soft agar than parental populations, and the anchorage-independent phenotype was stable for eight passages, at which time cells senesced. Anchorage-independent cell strains derived from metal salt-treated cells were not resistant to the cytotoxicity of metal salts, indicating metal salts induced rather than selected for anchorage independence. Nine of 10 cell strains derived from metal compound- or MNNG-induced anchorage-independent colonies displayed the same or lower saturation densities than untreated human fibroblasts. None of these cell strains escaped senescence or showed definitive morphological transformation. MNNG (1 micrograms/ml) induced anchorage independence and mutation to ouabain resistance and 6-thioguanine resistance in HFC, but concentrations of Ni2S3 that induced anchorage independence did not induce mutation at either locus in HFC. These results demonstrate that carcinogenic metal salts induce stable anchorage independence early in human diploid foreskin fibroblasts, and this anchorage independence is independent of other in vitro markers of fibroblast transformation, such as focus formation or immortality. Metal salt induction of anchorage independence can now be used as an assay to study mechanisms of genotoxicity exerted by carcinogenic metal compounds in human cells."
81889,Szulczewski et al. 1997,Comparison of XANES analyses and extractions to determine chromium speciation in contaminated soils,"#Chromium-contaminated soils from three sites in Wisconsin were analyzed for the total concentration of chromium with neutron activation analysis, extractable Cr(VI) with a typical phosphate buffer and exchangeable Cr(VI) with isotope dilution analysis. X-ray absorption near-edge structure (XANES) spectroscopy provided a physical method for determining the ratio of Cr(VI):Cr(III) in the contaminated soils. In most samples, less than 10% of the total Cr was present as Cr(VI). Of the total Cr(VI) measured with XANES analysis, only a fraction was isotopically exchangeable, and an even smaller fraction of the total Cr(VI) was extracted with a phosphate buffer. The speciation and extraction of chromium in actual contaminated soils are apparently more complex than traditional chemical methods can show.","Comparison of XANES analyses and extractions to determine chromium speciation in contaminated soils Abs: #Chromium-contaminated soils from three sites in Wisconsin were analyzed for the total concentration of chromium with neutron activation analysis, extractable Cr(VI) with a typical phosphate buffer and exchangeable Cr(VI) with isotope dilution analysis. X-ray absorption near-edge structure (XANES) spectroscopy provided a physical method for determining the ratio of Cr(VI):Cr(III) in the contaminated soils. In most samples, less than 10% of the total Cr was present as Cr(VI). Of the total Cr(VI) measured with XANES analysis, only a fraction was isotopically exchangeable, and an even smaller fraction of the total Cr(VI) was extracted with a phosphate buffer. The speciation and extraction of chromium in actual contaminated soils are apparently more complex than traditional chemical methods can show."
81098,Yang et al. 1996,Lead acetate mutagenicity and mutational spectrum in the hypoxanthine guanine phosphoribosyltransferase gene of Chinese hamster ovary K1 cells,,Lead acetate mutagenicity and mutational spectrum in the hypoxanthine guanine phosphoribosyltransferase gene of Chinese hamster ovary K1 cells Abs: 
80210,Finley et al. 1996,Assessment of airborne hexavalent chromium in the home following use of contaminated tapwater,"Field studies were conducted to estimate the plausible uptake of hexavalent chromium [Cr(VI)] aerosols inhaled during indoor residential use of a shower or an evaporative cooler supplied with water containing Cr(VI). In the evaporative cooler study, water concentrations of 20 mg Cr(VI)/L did not produce an increased concentration of airborne Cr(VI). The indoor air concentration of Cr(VI), measured over 24 hours of use, was 0.3-2.7 ng/m3, about the same as the concurrent outdoor concentrations. In the shower study, the average airborne concentrations of Cr(VI) aerosols at breathing-zone height ranged from 87 to 324 ng Cr(VI)/m3 when the water concentration of Cr(VI) was 0.89 to 11.5 mg/L. The Cr(VI) concentration in air was correlated directly to water concentration. The lifetime average daily doses and incremental cancer risk estimates corresponding to 30-year residential exposures were calculated using the measurements in this study and published exposure guidelines. The plausible upperbound lifetime cancer risk associated with continuous exposure to &quot;background&quot; Cr(VI) in outdoor air was estimated at 6.9 per million for a person exposed during ages 0-30, and 4.0 per million for ages 30-60. Similarly estimated upperbound cancer risks due to inhalation of shower aerosols from water containing 2-10 mg Cr(VI)/L over the same exposure period ranged from 0.9 to 5.5 per million. Our calculations demonstrate that shower aerosols do not contribute appreciably to background Cr(VI) exposures and risks, even at concentrations exceeding 2 mg Cr(VI)/L, which exhibit a discernible and unaesthetic yellow color that may limit the potential for long-term exposures of this type. We conclude that exposure to indoor aerosols from water containing Cr(VI) is unlikely to create a health hazard at concentrations up to 10 mg Cr(VI)/L. Furthermore, these aerosol measurements may be relevant to estimating airborne exposures to other nonvolatile chemicals.","Assessment of airborne hexavalent chromium in the home following use of contaminated tapwater Abs: Field studies were conducted to estimate the plausible uptake of hexavalent chromium [Cr(VI)] aerosols inhaled during indoor residential use of a shower or an evaporative cooler supplied with water containing Cr(VI). In the evaporative cooler study, water concentrations of 20 mg Cr(VI)/L did not produce an increased concentration of airborne Cr(VI). The indoor air concentration of Cr(VI), measured over 24 hours of use, was 0.3-2.7 ng/m3, about the same as the concurrent outdoor concentrations. In the shower study, the average airborne concentrations of Cr(VI) aerosols at breathing-zone height ranged from 87 to 324 ng Cr(VI)/m3 when the water concentration of Cr(VI) was 0.89 to 11.5 mg/L. The Cr(VI) concentration in air was correlated directly to water concentration. The lifetime average daily doses and incremental cancer risk estimates corresponding to 30-year residential exposures were calculated using the measurements in this study and published exposure guidelines. The plausible upperbound lifetime cancer risk associated with continuous exposure to &quot;background&quot; Cr(VI) in outdoor air was estimated at 6.9 per million for a person exposed during ages 0-30, and 4.0 per million for ages 30-60. Similarly estimated upperbound cancer risks due to inhalation of shower aerosols from water containing 2-10 mg Cr(VI)/L over the same exposure period ranged from 0.9 to 5.5 per million. Our calculations demonstrate that shower aerosols do not contribute appreciably to background Cr(VI) exposures and risks, even at concentrations exceeding 2 mg Cr(VI)/L, which exhibit a discernible and unaesthetic yellow color that may limit the potential for long-term exposures of this type. We conclude that exposure to indoor aerosols from water containing Cr(VI) is unlikely to create a health hazard at concentrations up to 10 mg Cr(VI)/L. Furthermore, these aerosol measurements may be relevant to estimating airborne exposures to other nonvolatile chemicals."
79931,Hobbesland et al. 1996,A study of mortality among 14730 male workers in 12 Norwegian ferroalloy plants: cohort characteristics and the main causes of death,Work Environment Fund of the Confederation of Norwegian Business and Industry; Norwegian Council for Science and Humanities.,A study of mortality among 14730 male workers in 12 Norwegian ferroalloy plants: cohort characteristics and the main causes of death Abs: Work Environment Fund of the Confederation of Norwegian Business and Industry; Norwegian Council for Science and Humanities.
79425,Campbell et al. 1995,Urban air quality and human health: a Toronto perspective,"BIOSIS COPYRIGHT: BIOL ABS. A study was undertaken to examine the health implications of ambient air quality in Toronto. Selected criteria pollutants were measured at low, medium and high traffic sites. Criteria pollutants emitted from vehicles showed a direct relationship with traffic density. Three pollutants (ozone, nitrogen dioxide and particulates) overlapped periodically with levels demonstrated nt he scientific literature to have adverse effects on human health. In addition, trace toxic compounds were measured at various Toronto locations and supplemented with data from other agencies. Based on composite data from 25 sampling locations, 160 compounds, including several carcinogens, were detected. The health significance of these pollutants was examined through quantitative risk assessment procedures. For several chemicals detected, levels were sufficiently high to raise concerns for public health. This study illustrates how one health unit utilized and supplemented provincial and federal air","Urban air quality and human health: a Toronto perspective Abs: BIOSIS COPYRIGHT: BIOL ABS. A study was undertaken to examine the health implications of ambient air quality in Toronto. Selected criteria pollutants were measured at low, medium and high traffic sites. Criteria pollutants emitted from vehicles showed a direct relationship with traffic density. Three pollutants (ozone, nitrogen dioxide and particulates) overlapped periodically with levels demonstrated nt he scientific literature to have adverse effects on human health. In addition, trace toxic compounds were measured at various Toronto locations and supplemented with data from other agencies. Based on composite data from 25 sampling locations, 160 compounds, including several carcinogens, were detected. The health significance of these pollutants was examined through quantitative risk assessment procedures. For several chemicals detected, levels were sufficiently high to raise concerns for public health. This study illustrates how one health unit utilized and supplemented provincial and federal air"
79246,Piegorsch and  Margolin 1989,Quantitative methods for assessing a synergistic or potentiated genotoxic response,"The problem of assessing chemical interactions in studies of genotoxicity is discussed. Attention is focused on assessing possible synergism or potentiation when the observed genotoxic response is binary (yes-no). Different forms of enhancement are distinguished based upon different assumptions on the genotoxic activity of the experimental treatments. A generalized linear statistical model is considered that links the probability of the binary response to the doses, and data-analytic strategies are described for detecting synergy and potentiation in factorially designed experiments. This approach is illustrated with a series of analyses of various genotoxicity data-sets.","Quantitative methods for assessing a synergistic or potentiated genotoxic response Abs: The problem of assessing chemical interactions in studies of genotoxicity is discussed. Attention is focused on assessing possible synergism or potentiation when the observed genotoxic response is binary (yes-no). Different forms of enhancement are distinguished based upon different assumptions on the genotoxic activity of the experimental treatments. A generalized linear statistical model is considered that links the probability of the binary response to the doses, and data-analytic strategies are described for detecting synergy and potentiation in factorially designed experiments. This approach is illustrated with a series of analyses of various genotoxicity data-sets."
79098,Wiegand et al. 1987,Bioavailability and metabolism of hexavalent chromium compounds,"Intratracheal instillation of 51CrCl3 in anaesthetized rabbits resulted in partial absorption. In blood, the absorbed material was entirely confined to the plasma compartment. Only trace amounts were deposited in liver and kidney. By contrast, after similar application of Na, 51CrO4 the bulk of blood radioactivity was present in red blood cells (RBC). Substantial deposition occurred in liver and kidneys. It is concluded that Cr(VI) may enter the body unreduced via the lung and is partially deposited in cells over a prolonged period of time. Since chromium was accumulated in liver after administration of Cr(VI) we investigated the intracellular disposition of Cr(VI) in the isolated perfused liver. No significant sex differences in chromium distribution were observed. At the end of the experiments (1 h), 60% of the applied dose (312?g Cr/liver) was located in the cytosol, whilst 14% was in the mitochondria, 9% in the microsomal pellet and 2% was associated with the nuclei. Gel chromatography of the cytosolic compartment showed that the overwhelming part of chromium was eluted in fractions with an apparent molecular weight of 6,000 dalton. These fractions exhibited absorption maxima at 410nm and 548nm. It is concluded, that cytosolic reduction might be the main intracellular redox pathway for chromates. This view was confirmed by monitoring the reaction of Cr(VI) with GSH in vitro. GSH reduced Cr(VI) without further cofactors under formation of GSH-chromium complexes, which possibly represent major intermediates in the metabolism of Cr(VI).","Bioavailability and metabolism of hexavalent chromium compounds Abs: Intratracheal instillation of 51CrCl3 in anaesthetized rabbits resulted in partial absorption. In blood, the absorbed material was entirely confined to the plasma compartment. Only trace amounts were deposited in liver and kidney. By contrast, after similar application of Na, 51CrO4 the bulk of blood radioactivity was present in red blood cells (RBC). Substantial deposition occurred in liver and kidneys. It is concluded that Cr(VI) may enter the body unreduced via the lung and is partially deposited in cells over a prolonged period of time. Since chromium was accumulated in liver after administration of Cr(VI) we investigated the intracellular disposition of Cr(VI) in the isolated perfused liver. No significant sex differences in chromium distribution were observed. At the end of the experiments (1 h), 60% of the applied dose (312?g Cr/liver) was located in the cytosol, whilst 14% was in the mitochondria, 9% in the microsomal pellet and 2% was associated with the nuclei. Gel chromatography of the cytosolic compartment showed that the overwhelming part of chromium was eluted in fractions with an apparent molecular weight of 6,000 dalton. These fractions exhibited absorption maxima at 410nm and 548nm. It is concluded, that cytosolic reduction might be the main intracellular redox pathway for chromates. This view was confirmed by monitoring the reaction of Cr(VI) with GSH in vitro. GSH reduced Cr(VI) without further cofactors under formation of GSH-chromium complexes, which possibly represent major intermediates in the metabolism of Cr(VI)."
79094,Von Burg and  Liu 1993,Chromium and hexavalent chromium,Biosis copyright: biol abs. rrm mouse rat human acute toxicity chronic toxicity immunotoxicity neurotoxicity reproductive toxicity genotoxicity carcinogenicity environmental toxicity,Chromium and hexavalent chromium Abs: Biosis copyright: biol abs. rrm mouse rat human acute toxicity chronic toxicity immunotoxicity neurotoxicity reproductive toxicity genotoxicity carcinogenicity environmental toxicity
79093,Varma et al. 1994,Acute renal failure in a case of fatal chromic acid poisoning,"Despite its frequent use in industry, acute poisoning by chromic acid has very rarely been reported. We report a patient who developed massive gastrointestinal hemorrhage, acute renal failure, and hepatic injury following chromic acid ingestion, and subsequently died. Postmortem liver and kidney biopsies revealed centrilobular necrosis and severe acute tubular necrosis, respectively.","Acute renal failure in a case of fatal chromic acid poisoning Abs: Despite its frequent use in industry, acute poisoning by chromic acid has very rarely been reported. We report a patient who developed massive gastrointestinal hemorrhage, acute renal failure, and hepatic injury following chromic acid ingestion, and subsequently died. Postmortem liver and kidney biopsies revealed centrilobular necrosis and severe acute tubular necrosis, respectively."
79090,Stern 1988,Indicators of matrix dependent variation in effective dose for chromium and nickel aerosol exposures,"Inhaled particulates containing Cr and Ni are partially cleared or dissolved thus contributing to short-term internal exposures and partial retention in airways and airspaces. The retained fraction may continuously contribute to internal exposure after external exposure has ceased, through intra- and extracellular chemical processes which continuously liberate various metallic species; i.e. via an active deposit. Recent experiments with Ni and Cr compounds, and freshly produced welding fumes, which contain Ni and Cr, demonstrate a strong dependence of the distribution of these metals on oxidation state, solubility, bioavailability and toxicity as measured by in-vitro bioassay, depending on the collection, storage and analytical technique. It is suggested that exposure limits must consider the wide variation in short- and long-term delivered dose of toxic metals to target tissue with matrix, and that current protocols may be inadequate to protect workers in different industries involving exposures to widely different types of aerosols having only the same chemical element in common.","Indicators of matrix dependent variation in effective dose for chromium and nickel aerosol exposures Abs: Inhaled particulates containing Cr and Ni are partially cleared or dissolved thus contributing to short-term internal exposures and partial retention in airways and airspaces. The retained fraction may continuously contribute to internal exposure after external exposure has ceased, through intra- and extracellular chemical processes which continuously liberate various metallic species; i.e. via an active deposit. Recent experiments with Ni and Cr compounds, and freshly produced welding fumes, which contain Ni and Cr, demonstrate a strong dependence of the distribution of these metals on oxidation state, solubility, bioavailability and toxicity as measured by in-vitro bioassay, depending on the collection, storage and analytical technique. It is suggested that exposure limits must consider the wide variation in short- and long-term delivered dose of toxic metals to target tissue with matrix, and that current protocols may be inadequate to protect workers in different industries involving exposures to widely different types of aerosols having only the same chemical element in common."
79088,Singh et al. 1990,Effects of chromium on cellular systems in animals,"Chromium is a heavy metal belonging to subgroup vib of the periodic table. in nature it is present mainly as trivalent but hexavalent form has also been found. the positively charged cr3+ ion has a tendency to form very stable complexes with negatively charged inorganic or organic particles present in aqueous solutions. therefore, hardly any uncomplexed chromic compounds can be found in the natural state. interest in the toxic effects of chromium has increased following the increased exposure of human beings and animals to different forms of this metal. the recommended or suggested safe and adequate intake of chromium was established at 50 to 200 ug for human adult. exposure to cr may occur by: (i) entrance through mouth with food or water; finally taken into blood stream through intestinal absorption. (ii) injected into blood stream intraperitoneally or intravenously. this is more effective than any other type of exposure. (iii) inhalation affecting respiratory system or trachea. it is most common in workers engaged in chromium industry. genotoxicity of chromium compounds is generally attributed to the oxidized hexavalent form whereas the reduced trivalent form is commonly considered inactive. evidences for carcinogenicity of cr to humans were considered sufficient by iarc on the basis of assessed increased incidence of lung cancer among workers in the chromate producing industry and possibly also among cr platers and cr alloy workers. the carcinogenicity, mutagenicity and cytotoxicity of different chromium compounds, particularly cr(vi), vary remarkably due to their differential solubility, diffusibility, stability and reactivity. these factors heavily influence their biological activity and can play very different roles in the induction of mutations, cancers and chromosomal aberrations. intracellular reduction of cr(vi) or cr(iii) and the reaction of cr(iii) with dna may be the critical events in chromium carcinogenesis. the carcinogenic potency of different chromium compounds may also be largely influenced by the exposure of dna of the target to sufficient amount of active cr(iii) for a long period. the solubility in biological fluids is probably very important since it determines the speed of removal of the compound from the target cells. researches on clastogenic effects of cr showed that both cr6+ and cr3+ were able to induce chromosome aberrations, whereas cr3+ was incapable of inducing sister chromatid exchanges. hexavalent chromium compounds induced marked cytotoxicity and clastogenic action on mammalian cell cultures and in rodents in vivo and both chromosomal aberrations and sister chromatid exchanges. cr(vi) was regarded as the active form which penetrated into the cell, but the final mutagenic and cytogenetic effects were due to its intranuclear reduction to cr(iii).","Effects of chromium on cellular systems in animals Abs: Chromium is a heavy metal belonging to subgroup vib of the periodic table. in nature it is present mainly as trivalent but hexavalent form has also been found. the positively charged cr3+ ion has a tendency to form very stable complexes with negatively charged inorganic or organic particles present in aqueous solutions. therefore, hardly any uncomplexed chromic compounds can be found in the natural state. interest in the toxic effects of chromium has increased following the increased exposure of human beings and animals to different forms of this metal. the recommended or suggested safe and adequate intake of chromium was established at 50 to 200 ug for human adult. exposure to cr may occur by: (i) entrance through mouth with food or water; finally taken into blood stream through intestinal absorption. (ii) injected into blood stream intraperitoneally or intravenously. this is more effective than any other type of exposure. (iii) inhalation affecting respiratory system or trachea. it is most common in workers engaged in chromium industry. genotoxicity of chromium compounds is generally attributed to the oxidized hexavalent form whereas the reduced trivalent form is commonly considered inactive. evidences for carcinogenicity of cr to humans were considered sufficient by iarc on the basis of assessed increased incidence of lung cancer among workers in the chromate producing industry and possibly also among cr platers and cr alloy workers. the carcinogenicity, mutagenicity and cytotoxicity of different chromium compounds, particularly cr(vi), vary remarkably due to their differential solubility, diffusibility, stability and reactivity. these factors heavily influence their biological activity and can play very different roles in the induction of mutations, cancers and chromosomal aberrations. intracellular reduction of cr(vi) or cr(iii) and the reaction of cr(iii) with dna may be the critical events in chromium carcinogenesis. the carcinogenic potency of different chromium compounds may also be largely influenced by the exposure of dna of the target to sufficient amount of active cr(iii) for a long period. the solubility in biological fluids is probably very important since it determines the speed of removal of the compound from the target cells. researches on clastogenic effects of cr showed that both cr6+ and cr3+ were able to induce chromosome aberrations, whereas cr3+ was incapable of inducing sister chromatid exchanges. hexavalent chromium compounds induced marked cytotoxicity and clastogenic action on mammalian cell cultures and in rodents in vivo and both chromosomal aberrations and sister chromatid exchanges. cr(vi) was regarded as the active form which penetrated into the cell, but the final mutagenic and cytogenetic effects were due to its intranuclear reduction to cr(iii)."
79087,Serita et al. 1990,Development of an inhalation system of high melting point metal fumes and its use for exposure of rats to chromium and nickel fumes,"An experimental inhalation system was developed for fumes generated from powders of high melting point metals such as chromium, nickel, manganese and iron. The system consisted of a plasma flame metal sprayer as a fume generator, a granular bed type fume collector, a fluidized bed aerosol generator, an exposure and a control chamber of a horizontal-flow type and inhalant monitoring and controlling units. Performance of the chambers was ensured by a distribution test using flyash as a test aerosol. Using this system, rats were exposed to chromium fumes for one week or to nickel fumes for two months. The exposure concentrations of the chromium and nickel fumes were 1.85 +/- 0.55 mg/m3 and 0.51 +/- 0.15 mg/m3 (mean +/- SD), near the target levels of 2 mg/m3 and 0.5 mg/m3, respectively. The mass median aerodynamic diameter and the geometric standard deviation of the chromium fumes were 2.1 microns and 2.00, respectively. Those of the nickel fumes were 3.7 microns and 1.74, respectively. Species analysis of these fume particles revealed that 26.4% of the total chromium was hexavalent and the residue was trivalent and that 1-3% of the total nickel was nickel(III) and the residue was nickel(II). Inhaled-metal concentrations in the lungs showed steady increases with the exposure periods and were within the normal range of variation. On the basis of these results, it is concluded that this system is useful for long-term inhalation experiments using high melting point metal fumes.","Development of an inhalation system of high melting point metal fumes and its use for exposure of rats to chromium and nickel fumes Abs: An experimental inhalation system was developed for fumes generated from powders of high melting point metals such as chromium, nickel, manganese and iron. The system consisted of a plasma flame metal sprayer as a fume generator, a granular bed type fume collector, a fluidized bed aerosol generator, an exposure and a control chamber of a horizontal-flow type and inhalant monitoring and controlling units. Performance of the chambers was ensured by a distribution test using flyash as a test aerosol. Using this system, rats were exposed to chromium fumes for one week or to nickel fumes for two months. The exposure concentrations of the chromium and nickel fumes were 1.85 +/- 0.55 mg/m3 and 0.51 +/- 0.15 mg/m3 (mean +/- SD), near the target levels of 2 mg/m3 and 0.5 mg/m3, respectively. The mass median aerodynamic diameter and the geometric standard deviation of the chromium fumes were 2.1 microns and 2.00, respectively. Those of the nickel fumes were 3.7 microns and 1.74, respectively. Species analysis of these fume particles revealed that 26.4% of the total chromium was hexavalent and the residue was trivalent and that 1-3% of the total nickel was nickel(III) and the residue was nickel(II). Inhaled-metal concentrations in the lungs showed steady increases with the exposure periods and were within the normal range of variation. On the basis of these results, it is concluded that this system is useful for long-term inhalation experiments using high melting point metal fumes."
79078,Ratnasooriya and  Balasuriya 1992,Effects on reproduction in male rats following short-term exposure to hexavalent chromium,,Effects on reproduction in male rats following short-term exposure to hexavalent chromium Abs: 
79074,Peltonen and  Fraki 1983,Prevalence of dichromate sensitivity,"In a population of 822 healthy adult volunteers, 2% of the 410 men and 1.5% of the 412 women showed a positive patch test reaction to 0.5% potassium dichromate in pet. Most of the positive reactions (10/14) occurred in the group of 110 offset printers, lithographers and printing plant cleaners with present occupational exposure to chromium. Among the remaining test population, sensitivity to dichromate was rare (4/712). Of the 14 chromium-allergic persons, 9 had present or past hand eczema, 2 had eczema only on the face, and 3 could not recall having had any skin trouble. In 2981 clinic patients tested during a 5-year period, the frequency of chromate sensitivity was 6.8% in men and 2.8% in women among all patients tested, but 20% in men and 8% in women of the 499 patients with occupational hand eczema. The incidence of chromium allergy in separate occupational groups is presented.","Prevalence of dichromate sensitivity Abs: In a population of 822 healthy adult volunteers, 2% of the 410 men and 1.5% of the 412 women showed a positive patch test reaction to 0.5% potassium dichromate in pet. Most of the positive reactions (10/14) occurred in the group of 110 offset printers, lithographers and printing plant cleaners with present occupational exposure to chromium. Among the remaining test population, sensitivity to dichromate was rare (4/712). Of the 14 chromium-allergic persons, 9 had present or past hand eczema, 2 had eczema only on the face, and 3 could not recall having had any skin trouble. In 2981 clinic patients tested during a 5-year period, the frequency of chromate sensitivity was 6.8% in men and 2.8% in women among all patients tested, but 20% in men and 8% in women of the 499 patients with occupational hand eczema. The incidence of chromium allergy in separate occupational groups is presented."
79069,O'Flaherty 1993,A pharmacokinetic model for chromium,"Reduction of hexavalent chromium (Cr(VI)) to trivalent chromium (Cr(III)) and differential kinetics of Cr(III) and Cr(VI) are important determinants of the disposition and toxicity of chromium. A physiologically based model of chromium disposition in the rat has been developed. The model takes into account different absorption and reduction rates in the lung and gastrointestinal tract; different efficiencies of transfer of Cr(III) and Cr(VI) into tissues including erythrocytes, where Cr(VI) is reduced to Cr(III) and retained for an extended period of time; uptake and storage in bone; and reabsorption of chromium from the gastrointestinal tract. The model is shown to be capable of generating the observed distributions of chromium between plasma and erythrocytes in rats given Cr(VI) intragastrically, intraduodenally, or intratracheally.","A pharmacokinetic model for chromium Abs: Reduction of hexavalent chromium (Cr(VI)) to trivalent chromium (Cr(III)) and differential kinetics of Cr(III) and Cr(VI) are important determinants of the disposition and toxicity of chromium. A physiologically based model of chromium disposition in the rat has been developed. The model takes into account different absorption and reduction rates in the lung and gastrointestinal tract; different efficiencies of transfer of Cr(III) and Cr(VI) into tissues including erythrocytes, where Cr(VI) is reduced to Cr(III) and retained for an extended period of time; uptake and storage in bone; and reabsorption of chromium from the gastrointestinal tract. The model is shown to be capable of generating the observed distributions of chromium between plasma and erythrocytes in rats given Cr(VI) intragastrically, intraduodenally, or intratracheally."
79066,Nagaya et al. 1994,Early renal effects of occupational exposure to low-level hexavalent chromium,"To detect early renal effects of occupational exposure to hexavalent chromium (Cr), urinary total proteins (U-TP), urinary albumin (U-Alb) and urinary retinol-binding protein (U-RBP) were determined in 166 male Cr platers and 106 male controls. The mean employment time in Cr plating for the platers was 12.6 years. Urinary Cr (U-Cr), which was determined as an index of Cr exposure, ranged from ""not detected"" to 19.91 micrograms/g creatinine in the platers. The U-Cr level was lower than those in other previous studies. Age-adjusted U-TP, U-Alb or U-RBP levels were not different between the platers and the controls. In the platers, a significant positive correlation was found between age-adjusted U-TP and U-Cr, but U-Cr had no significant relation to age-adjusted U-Alb or U-RBP level. Employment time had no effect on any age-adjusted urinary proteins. The Cr exposure may have been too low to induce definite renal dysfunction. Early renal effects of low-level Cr exposure may be mild, and may not be specific to renal function.","Early renal effects of occupational exposure to low-level hexavalent chromium Abs: To detect early renal effects of occupational exposure to hexavalent chromium (Cr), urinary total proteins (U-TP), urinary albumin (U-Alb) and urinary retinol-binding protein (U-RBP) were determined in 166 male Cr platers and 106 male controls. The mean employment time in Cr plating for the platers was 12.6 years. Urinary Cr (U-Cr), which was determined as an index of Cr exposure, ranged from ""not detected"" to 19.91 micrograms/g creatinine in the platers. The U-Cr level was lower than those in other previous studies. Age-adjusted U-TP, U-Alb or U-RBP levels were not different between the platers and the controls. In the platers, a significant positive correlation was found between age-adjusted U-TP and U-Cr, but U-Cr had no significant relation to age-adjusted U-Alb or U-RBP level. Employment time had no effect on any age-adjusted urinary proteins. The Cr exposure may have been too low to induce definite renal dysfunction. Early renal effects of low-level Cr exposure may be mild, and may not be specific to renal function."
79063,Miyai et al. 1980,[Absorption and accumulation of chromium in animals after chromium compound inhalation: 2. comparison of various chromium compounds],"To elucidate the effects of the oxidation state and solubility of Cr compounds on pulmonary absorption and body distribution after their inhalation, sodium chromate, calcium chromate, barium chromate, chromium (III) chloride and chromium (III) oxide were compared in mice by using 51Cr as a tracer. The elimination of Cr from the local, within 48 h after intratracheal administration, was 85% of the dose in sodium chromate and calcium chromate, and only 12% in barium chromate. Urinary excretion of calcium chromate was larger than fecal excretion, and barium chromate was conversely larger in the feces. Within 17 days after 30-min inhalation of the compounds, the following results were obtained. Hexavalent Cr compounds showed a higher pulmonary deposition rate and also a higher pulmonary absorption rate to the inhaled amount or the deposited amount, compared to the trivalent Cr compounds. Among hexavalent Cr compounds, barium chromate showed a low absorption rate near that of the trivalent Cr compounds. These facts suggested that pulmonary absorption of Cr compounds is affected due to the oxidation state and solubility of the compounds. The biological half time, which was observed during the later period after inhalation, was 7.5 days for sodium chromate, 18 days for barium chromate, about 25 days for chromium (III) chloride and a longer time for chromium (III) oxide. The amount of Cr distributed in the body, excluding the respiratory system, was greater in sodium chromate and calcium chromate, moderate in barium chromate, and smaller in chromic chloride and chromic oxide, compared with each other. A Cr accumulation or retention curve in the kidney and spleen differed significantly in some of the compounds. Almost all the blood Cr was found in red cells at the later period after hexavalent Cr exposure, while little of that was found but disappeared quickly after trivalent Cr exposure. Cr excretion was greater in feces than in urine in both hexavalent and trivalent Cr compounds, but the urinary excretion of hexavalent Cr compounds, except for barium chromate, was greater than that of the trivalent Cr compounds.","[Absorption and accumulation of chromium in animals after chromium compound inhalation: 2. comparison of various chromium compounds] Abs: To elucidate the effects of the oxidation state and solubility of Cr compounds on pulmonary absorption and body distribution after their inhalation, sodium chromate, calcium chromate, barium chromate, chromium (III) chloride and chromium (III) oxide were compared in mice by using 51Cr as a tracer. The elimination of Cr from the local, within 48 h after intratracheal administration, was 85% of the dose in sodium chromate and calcium chromate, and only 12% in barium chromate. Urinary excretion of calcium chromate was larger than fecal excretion, and barium chromate was conversely larger in the feces. Within 17 days after 30-min inhalation of the compounds, the following results were obtained. Hexavalent Cr compounds showed a higher pulmonary deposition rate and also a higher pulmonary absorption rate to the inhaled amount or the deposited amount, compared to the trivalent Cr compounds. Among hexavalent Cr compounds, barium chromate showed a low absorption rate near that of the trivalent Cr compounds. These facts suggested that pulmonary absorption of Cr compounds is affected due to the oxidation state and solubility of the compounds. The biological half time, which was observed during the later period after inhalation, was 7.5 days for sodium chromate, 18 days for barium chromate, about 25 days for chromium (III) chloride and a longer time for chromium (III) oxide. The amount of Cr distributed in the body, excluding the respiratory system, was greater in sodium chromate and calcium chromate, moderate in barium chromate, and smaller in chromic chloride and chromic oxide, compared with each other. A Cr accumulation or retention curve in the kidney and spleen differed significantly in some of the compounds. Almost all the blood Cr was found in red cells at the later period after hexavalent Cr exposure, while little of that was found but disappeared quickly after trivalent Cr exposure. Cr excretion was greater in feces than in urine in both hexavalent and trivalent Cr compounds, but the urinary excretion of hexavalent Cr compounds, except for barium chromate, was greater than that of the trivalent Cr compounds."
79059,Lavelle 1991,Mechanisms of toxicity/carcinogenicity and Superfund decisions,"Heavy metals that contaminate soils and water usually exist in various oxidation states and form a number of compounds with different physical and chemical characteristics. These differences are often reflected in dramatic variation in toxicokinetic and biologic properties. Such variation in properties, critical in determining intrinsic toxicity, often causes a great deal of uncertainty in analyses of public health risks at sites where metal exposure is evaluated. In the Superfund program, such uncertainties may substantially undermine attempts to characterize potential impacts to populations exposed to metals from improperly disposed waste. In the case of chromium, risk assessment uncertainties can be considerable and fall generally into two categories. First, there is almost no information on potential health effects due to chronic oral exposure to chromium-containing compounds, and a nonquantifiable and probably large uncertainty exists in establishing no-effect levels. In fact, reference doses (RfDs) for CrIII and CrVI are based on chronic studies in which no adverse effects were seen even at the highest dose. Considerations of bioavailability, deduced from site characterization data, and acute toxicity indicate that general application of these RfDs may lead to highly inaccurate estimations of risk. Second, because of the ready reduction of CrVI in biological systems, it has not been possible to separate effects of CrVI from those of CrIII. Thus, data on the relative toxicity and carcinogenicity of these two species is sparse and difficult to interpret. Moreover, kinetic considerations make it difficult to determine the site and rates of reduction of CrVI. This makes prediction of target site concentrations of the two species difficult.(ABSTRACT TRUNCATED AT 250 WORDS)","Mechanisms of toxicity/carcinogenicity and Superfund decisions Abs: Heavy metals that contaminate soils and water usually exist in various oxidation states and form a number of compounds with different physical and chemical characteristics. These differences are often reflected in dramatic variation in toxicokinetic and biologic properties. Such variation in properties, critical in determining intrinsic toxicity, often causes a great deal of uncertainty in analyses of public health risks at sites where metal exposure is evaluated. In the Superfund program, such uncertainties may substantially undermine attempts to characterize potential impacts to populations exposed to metals from improperly disposed waste. In the case of chromium, risk assessment uncertainties can be considerable and fall generally into two categories. First, there is almost no information on potential health effects due to chronic oral exposure to chromium-containing compounds, and a nonquantifiable and probably large uncertainty exists in establishing no-effect levels. In fact, reference doses (RfDs) for CrIII and CrVI are based on chronic studies in which no adverse effects were seen even at the highest dose. Considerations of bioavailability, deduced from site characterization data, and acute toxicity indicate that general application of these RfDs may lead to highly inaccurate estimations of risk. Second, because of the ready reduction of CrVI in biological systems, it has not been possible to separate effects of CrVI from those of CrIII. Thus, data on the relative toxicity and carcinogenicity of these two species is sparse and difficult to interpret. Moreover, kinetic considerations make it difficult to determine the site and rates of reduction of CrVI. This makes prediction of target site concentrations of the two species difficult.(ABSTRACT TRUNCATED AT 250 WORDS)"
79058,Langard and  Nordhagen 1980,Small animal inhalation chambers and the significance of dust ingestion from the contaminated coat when exposing rats to zinc chromate,"The relative significance of dust ingestion during and after short-term inhalation exposure to a zinc chromate aerosol has been studied. Two groups of rats were exposed in the same dust cloud, one in open wire cages and the other in fiber glass tubes. The chromium excretion during the following 2 1/2 days was 8.4 times higher in faeces and 5.5 times higher in urine in the animals exposed in cages, compared with those exposed in tubes.","Small animal inhalation chambers and the significance of dust ingestion from the contaminated coat when exposing rats to zinc chromate Abs: The relative significance of dust ingestion during and after short-term inhalation exposure to a zinc chromate aerosol has been studied. Two groups of rats were exposed in the same dust cloud, one in open wire cages and the other in fiber glass tubes. The chromium excretion during the following 2 1/2 days was 8.4 times higher in faeces and 5.5 times higher in urine in the animals exposed in cages, compared with those exposed in tubes."
79055,Katz and  Salem 1993,The toxicology of chromium with respect to its chemical speciation: a review,"The properties of trivalent and hexavalent chromium are reviewed with respect to acute and chronic oral toxicity, dermal toxicity, systemic toxicity, toxicokinetics, cytotoxicity, genotoxicity and carcinogenicity. The hexavalent chromium compounds appear to be 10-100 times more toxic than the trivalent chromium compounds when both are administered by the oral route. Dermal irritancy and allergy are more frequently caused by contact with soluble hexavalent chromium compounds. The cytotoxicity of soluble and insoluble hexavalent chromium compounds to fibroblasts is 100-1000 times greater than that demonstrated by trivalent chromium compounds. In short-term tests, the hexavalent chromium compounds demonstrated genotoxic effects four times more frequently than did the trivalent chromium compounds. Carcinogenicity appears to be associated with the inhalation of the less soluble/insoluble hexavalent chromium compounds. The toxicology of chromium does not reside with the elemental form. It varies greatly among a wide variety of very different chromium compounds. Oxidation state and solubility are particularly important factors in considering the toxicity of chromium with respect to its chemical speciation.","The toxicology of chromium with respect to its chemical speciation: a review Abs: The properties of trivalent and hexavalent chromium are reviewed with respect to acute and chronic oral toxicity, dermal toxicity, systemic toxicity, toxicokinetics, cytotoxicity, genotoxicity and carcinogenicity. The hexavalent chromium compounds appear to be 10-100 times more toxic than the trivalent chromium compounds when both are administered by the oral route. Dermal irritancy and allergy are more frequently caused by contact with soluble hexavalent chromium compounds. The cytotoxicity of soluble and insoluble hexavalent chromium compounds to fibroblasts is 100-1000 times greater than that demonstrated by trivalent chromium compounds. In short-term tests, the hexavalent chromium compounds demonstrated genotoxic effects four times more frequently than did the trivalent chromium compounds. Carcinogenicity appears to be associated with the inhalation of the less soluble/insoluble hexavalent chromium compounds. The toxicology of chromium does not reside with the elemental form. It varies greatly among a wide variety of very different chromium compounds. Oxidation state and solubility are particularly important factors in considering the toxicity of chromium with respect to its chemical speciation."
79053,Johansen et al. 1994,Severe chronic inflammation of the mucous membranes in the eyes and upper respiratory tract due to work-related exposure to hexavalent chromium,Chronic inflammation of the skin and mucous membranes following prolonged exposure to high doses of toxic hexavalent chromium is well known in the occupational medical literature. Perforation of the nasal septum is a cardinal clinical feature. Late development of cancer in the respiratory system is established. A recently diagnosed case with an unusually severe affect on the eyes is described. The industrial usage of chromium and its toxicological profile is reviewed.,Severe chronic inflammation of the mucous membranes in the eyes and upper respiratory tract due to work-related exposure to hexavalent chromium Abs: Chronic inflammation of the skin and mucous membranes following prolonged exposure to high doses of toxic hexavalent chromium is well known in the occupational medical literature. Perforation of the nasal septum is a cardinal clinical feature. Late development of cancer in the respiratory system is established. A recently diagnosed case with an unusually severe affect on the eyes is described. The industrial usage of chromium and its toxicological profile is reviewed.
79048,Gao et al. 1993,Monitoring of total chromium in rat fluids and lymphocytes following intratracheal administration of soluble trivalent or hexavalent chromium compounds,"1. Intratracheal instillation of sodium dichromate (CrVI) and chromium acetate hydroxide (CrIII) to male Wistar rats gave rise to increased chromium concentrations in whole blood, plasma and urine up to 72 h post exposure; peak concentrations were reached at 6 h after exposure. 2. The ratio of whole blood chromium to plasma chromium concentrations was significantly different for Cr(VI) and Cr(III) treatments. Both blood chromium and plasma chromium assays should therefore be used for the assessment of chromium exposure. 3. Chromium was also detected in peripheral lymphocytes. Cr(VI), but not Cr(III) accumulated significantly in the lymphocytes after treatment. These cells have potential to be used for biomarkers of the assessment of exposure to chromium compounds.","Monitoring of total chromium in rat fluids and lymphocytes following intratracheal administration of soluble trivalent or hexavalent chromium compounds Abs: 1. Intratracheal instillation of sodium dichromate (CrVI) and chromium acetate hydroxide (CrIII) to male Wistar rats gave rise to increased chromium concentrations in whole blood, plasma and urine up to 72 h post exposure; peak concentrations were reached at 6 h after exposure. 2. The ratio of whole blood chromium to plasma chromium concentrations was significantly different for Cr(VI) and Cr(III) treatments. Both blood chromium and plasma chromium assays should therefore be used for the assessment of chromium exposure. 3. Chromium was also detected in peripheral lymphocytes. Cr(VI), but not Cr(III) accumulated significantly in the lymphocytes after treatment. These cells have potential to be used for biomarkers of the assessment of exposure to chromium compounds."
79044,Edel and  Sabbioni 1985,Pathways of Cr (III) and Cr (VI) in the rat after intratracheal administration,"51Cr-labelled Cr3+ and CrO2-4 solutions were administered intratracheally to male rats in doses of 0.1 and 10 micrograms of Cr per rat to evidentiate metabolic differences especially in the lung and in the mechanisms of excretion. Twenty four hours after administration the highest 51Cr amount was present in the lungs for both valency states, being in the Cr (III)-treated group, however, about two times higher. In all other tissues tested the values in the Cr (VI)-treated animals were much higher. Intracellularly, in the Cr (III)-treated group more than 40% of the total lung homogenate was found in the nuclear fraction and only 10% in the cytosol. In the Cr (VI)-treated group 25% was present in the nuclei and more than 50% in the cytosol. Gel filtration 24 h after intratracheal injection showed that in both cytosols chromium was eluted in three peaks including a low-molecular-weight component. Quantitatively, however, the ratios between the 51Cr associated with the three peaks were significantly different between the Cr (III)- and the Cr (VI)-treated animals. This suggests that binding of chromium to low-molecular-weight components should be involved in the passage of this element from the lung to the other tissues. Excretion studies for 7 days showed that after this time the Cr (III)-treated animals excreted about 4% of the dose via urine and more than 36% via faeces, whereas in the Cr (VI)-treated rats the 51Cr was eliminated nearly equally between urine and faeces.","Pathways of Cr (III) and Cr (VI) in the rat after intratracheal administration Abs: 51Cr-labelled Cr3+ and CrO2-4 solutions were administered intratracheally to male rats in doses of 0.1 and 10 micrograms of Cr per rat to evidentiate metabolic differences especially in the lung and in the mechanisms of excretion. Twenty four hours after administration the highest 51Cr amount was present in the lungs for both valency states, being in the Cr (III)-treated group, however, about two times higher. In all other tissues tested the values in the Cr (VI)-treated animals were much higher. Intracellularly, in the Cr (III)-treated group more than 40% of the total lung homogenate was found in the nuclear fraction and only 10% in the cytosol. In the Cr (VI)-treated group 25% was present in the nuclei and more than 50% in the cytosol. Gel filtration 24 h after intratracheal injection showed that in both cytosols chromium was eluted in three peaks including a low-molecular-weight component. Quantitatively, however, the ratios between the 51Cr associated with the three peaks were significantly different between the Cr (III)- and the Cr (VI)-treated animals. This suggests that binding of chromium to low-molecular-weight components should be involved in the passage of this element from the lung to the other tissues. Excretion studies for 7 days showed that after this time the Cr (III)-treated animals excreted about 4% of the dose via urine and more than 36% via faeces, whereas in the Cr (VI)-treated rats the 51Cr was eliminated nearly equally between urine and faeces."
79040,Cohen et al. 1993,Mechanisms of chromium carcinogenicity and toxicity,"Chromium, like many transition metal elements, is essential to life at low concentrations yet toxic to many systems at higher concentrations. In addition to the overt symptoms of acute chromium toxicity, delayed manifestations of chromium exposure become apparent by subsequent increases in the incidence of various human cancers. Chromium is widely used in numerous industrial processes, and as a result is a contaminant of many environmental systems. Chromium, in its myriad chemical forms and oxidation states, has been well studied in terms of its general chemistry and its interactions with biological molecules. However, the precise mechanisms by which chromium is both an essential metal and a carcinogen are not yet fully clear. The following review does not seek to embellish upon the proposed mechanisms of the toxic and carcinogenic actions of chromium, but rather provides a comprehensive review of these theories. The chemical nature of chromium compounds and how these properties impact upon the interactions of chromium with cellular and genetic targets, including animal and human hosts, are discussed.","Mechanisms of chromium carcinogenicity and toxicity Abs: Chromium, like many transition metal elements, is essential to life at low concentrations yet toxic to many systems at higher concentrations. In addition to the overt symptoms of acute chromium toxicity, delayed manifestations of chromium exposure become apparent by subsequent increases in the incidence of various human cancers. Chromium is widely used in numerous industrial processes, and as a result is a contaminant of many environmental systems. Chromium, in its myriad chemical forms and oxidation states, has been well studied in terms of its general chemistry and its interactions with biological molecules. However, the precise mechanisms by which chromium is both an essential metal and a carcinogen are not yet fully clear. The following review does not seek to embellish upon the proposed mechanisms of the toxic and carcinogenic actions of chromium, but rather provides a comprehensive review of these theories. The chemical nature of chromium compounds and how these properties impact upon the interactions of chromium with cellular and genetic targets, including animal and human hosts, are discussed."
79016,Bonde and  Ernst 1993,Male reproductive toxicology of chromium compounds,,Male reproductive toxicology of chromium compounds Abs: 
79011,Baruthio 1992,Toxic effects of chromium and its compounds,"Chromium was discovered in 1797 by Vauquelin. Numerous industrial applications raised chromium to a very important economic element. At the same time, with the development of its uses, the adverse effects of chromium compounds in human health were being defined. Trivalent chromium is an essential trace element in humans and in animals. Chromium as pure metal has no adverse effect. Little toxic effect is attributed to trivalent chromium when present in very large quantities. Both acute and chronic toxicity of chromium are mainly caused by hexavalent compounds. The most important toxic effects, after contact, inhalation, or ingestion of hexavalent chromium compounds are the following: dermatitis, allergic and eczematous skin reactions, skin and mucous membrane ulcerations, perforation of the nasal septum, allergic asthmatic reactions, bronchial carcinomas, gastro-enteritis, hepatocellular deficiency, and renal oligo anuric deficiency. Prevention of occupational risks, biological monitoring of workers, and treatment of poisoning are also reported.","Toxic effects of chromium and its compounds Abs: Chromium was discovered in 1797 by Vauquelin. Numerous industrial applications raised chromium to a very important economic element. At the same time, with the development of its uses, the adverse effects of chromium compounds in human health were being defined. Trivalent chromium is an essential trace element in humans and in animals. Chromium as pure metal has no adverse effect. Little toxic effect is attributed to trivalent chromium when present in very large quantities. Both acute and chronic toxicity of chromium are mainly caused by hexavalent compounds. The most important toxic effects, after contact, inhalation, or ingestion of hexavalent chromium compounds are the following: dermatitis, allergic and eczematous skin reactions, skin and mucous membrane ulcerations, perforation of the nasal septum, allergic asthmatic reactions, bronchial carcinomas, gastro-enteritis, hepatocellular deficiency, and renal oligo anuric deficiency. Prevention of occupational risks, biological monitoring of workers, and treatment of poisoning are also reported."
78553,Mumtaz et al. 2002,Gene induction studies and toxicity of chemical mixtures,"#As part of its mixtures program, the Agency for Toxic Substances and Disease Registry (ATSDR) supports in vitro and limited in vivo toxicity testing to further our understanding of the toxicity and health effects of chemical mixtures. There are increasing concerns that environmental chemicals adversely affect the health of humans and wildlife. These concerns have been augmented by the realization that exposure to chemicals often occurs to mixtures of these chemicals that may exhibit complex synergistic or antagonistic interactions. To address such concerns, we have conducted two studies with techniques that are being used increasingly in experimental toxicology. In the first study, six organochlorine pesticides (4,4 -DDT, 4,4 -DDD, 4,4 -DDE, aldrin, dieldrin, or endrin) were selected from the ATSDR Comprehensive Environmental Response, Compensation and Liability Act of 1980 (or Superfund) priority list and tested for their ability to modulate transcriptional activation of an estrogen-responsive reporter gene in transfected HeLa cells. In these assays, HeLa cells cotransfected with an expression vector encoding estrogen receptor and an estrogen-responsive chloramphenicol acetyltransferase (CAT) reporter plasmid were dosed with and without selected environmental chemicals either individually or in defined combinations. Estradiol consistently elicited 10- to 23-fold dose-dependent inductions in this assay. By contrast, all six of the organochlorine pesticides showed no detectable dose-related response when tested either individually or in binary combinations. Thus, these chemicals as binary mixtures do not exhibit any additional estrogenicity at the levels tested in these assays. In the second study, arsenic [As(V)], cadmium [Cd(II)], chromium [Cr(III, VI)], and lead [Pb(II)] were tested in a commercially developed assay system, CAT-Tox (L), to identify metal-responsive promoters and to determine whether the pattern of gene expression changed with a mixture of these metals. This assay employs a battery of recombinant HepG2 cell lines to test the transcriptional activation capacity of xenobiotics in any of 13 different signal-transduction pathways. Singly, As(V), Cd(II), Cr(III, VI), and Pb(II) produced complex induction profiles in these assays. However, no evidence of synergistic activity was detected with a mixture of Cd(II), Cr(III), and Pb(II). These results have shown metal activation of gene expression through several previously unreported signal-transduction pathways and thus suggest new directions for future studies into their biochemical mechanisms of toxicity. In conclusion, the (italic)in vitro(/italic) methods used in these studies provide insights into complex interactions that occur in cellular systems and could be used to identify biomarkers of exposure to other environmental chemical mixtures.","Gene induction studies and toxicity of chemical mixtures Abs: #As part of its mixtures program, the Agency for Toxic Substances and Disease Registry (ATSDR) supports in vitro and limited in vivo toxicity testing to further our understanding of the toxicity and health effects of chemical mixtures. There are increasing concerns that environmental chemicals adversely affect the health of humans and wildlife. These concerns have been augmented by the realization that exposure to chemicals often occurs to mixtures of these chemicals that may exhibit complex synergistic or antagonistic interactions. To address such concerns, we have conducted two studies with techniques that are being used increasingly in experimental toxicology. In the first study, six organochlorine pesticides (4,4 -DDT, 4,4 -DDD, 4,4 -DDE, aldrin, dieldrin, or endrin) were selected from the ATSDR Comprehensive Environmental Response, Compensation and Liability Act of 1980 (or Superfund) priority list and tested for their ability to modulate transcriptional activation of an estrogen-responsive reporter gene in transfected HeLa cells. In these assays, HeLa cells cotransfected with an expression vector encoding estrogen receptor and an estrogen-responsive chloramphenicol acetyltransferase (CAT) reporter plasmid were dosed with and without selected environmental chemicals either individually or in defined combinations. Estradiol consistently elicited 10- to 23-fold dose-dependent inductions in this assay. By contrast, all six of the organochlorine pesticides showed no detectable dose-related response when tested either individually or in binary combinations. Thus, these chemicals as binary mixtures do not exhibit any additional estrogenicity at the levels tested in these assays. In the second study, arsenic [As(V)], cadmium [Cd(II)], chromium [Cr(III, VI)], and lead [Pb(II)] were tested in a commercially developed assay system, CAT-Tox (L), to identify metal-responsive promoters and to determine whether the pattern of gene expression changed with a mixture of these metals. This assay employs a battery of recombinant HepG2 cell lines to test the transcriptional activation capacity of xenobiotics in any of 13 different signal-transduction pathways. Singly, As(V), Cd(II), Cr(III, VI), and Pb(II) produced complex induction profiles in these assays. However, no evidence of synergistic activity was detected with a mixture of Cd(II), Cr(III), and Pb(II). These results have shown metal activation of gene expression through several previously unreported signal-transduction pathways and thus suggest new directions for future studies into their biochemical mechanisms of toxicity. In conclusion, the (italic)in vitro(/italic) methods used in these studies provide insights into complex interactions that occur in cellular systems and could be used to identify biomarkers of exposure to other environmental chemical mixtures."
78369,Walker and  Cooper 1992,Air pollution emission factors for medical waste incinerators,,Air pollution emission factors for medical waste incinerators Abs: 
78137,Kasprzak 1995,Possible role of oxidative damage in metal-induced carcinogenesis,"BIOSIS COPYRIGHT: BIOL ABS. This review presents and evaluates evidence relevant to the mechanisms of metal carcinogenicity with special emphasis on the emerging hypothesis of the oxidative nature of metals' effect on DNA. The carcinogenic transition metals are capable of in vivo binding with the cell nucleus and causing promutagenic damage that includes DNA base modifications, inter- and intramolecular crosslnking of DNA and proteins, DNA strand breaks, rearrangements, and depurination. The chemistry of that damage and the resulting mutations observed in vitro and in metal-induced tumors are both characteristic for oxidative attack on DNA. The underlying mechanism involves various kinds of active oxygen and other radical species arising from metal-catalyzed redox reactions of O2, J2O2, lipid peroxides, and others, with certain amino acids, peptides, and proteins. Other metal-mediated pathogenic effects, such as enhancement of lipid peroxidation, stimulation of inflammation, inhibition of cellular","Possible role of oxidative damage in metal-induced carcinogenesis Abs: BIOSIS COPYRIGHT: BIOL ABS. This review presents and evaluates evidence relevant to the mechanisms of metal carcinogenicity with special emphasis on the emerging hypothesis of the oxidative nature of metals' effect on DNA. The carcinogenic transition metals are capable of in vivo binding with the cell nucleus and causing promutagenic damage that includes DNA base modifications, inter- and intramolecular crosslnking of DNA and proteins, DNA strand breaks, rearrangements, and depurination. The chemistry of that damage and the resulting mutations observed in vitro and in metal-induced tumors are both characteristic for oxidative attack on DNA. The underlying mechanism involves various kinds of active oxygen and other radical species arising from metal-catalyzed redox reactions of O2, J2O2, lipid peroxides, and others, with certain amino acids, peptides, and proteins. Other metal-mediated pathogenic effects, such as enhancement of lipid peroxidation, stimulation of inflammation, inhibition of cellular"
77916,Young et al. 1995,Action of metallic ions on the precocious development by rabbit sperm of motion patterns that are characteristic of hyperactivated motility,"BIOSIS COPYRIGHT: BIOL ABS. An earlier study demonstrated that rabbit sperm incubated for 16 hr under capacitation conditions acquire motility patterns identical to those seen in rabbit sperm capacitated in vivo. We now show that similar motion patterns develop after 0.5 hr incubation in a Trisbuffered medium, medium M. Development and decline of the motion patterns occurred in three phases each recognized by the character of the biphasic motion patterns. Hyperactivated sperm were objectively identified and quantified by a previously developed computer-directed model. The percentage of motile sperm that acquired hyperactivated motility and the period they remained in this state varied among sperm from different rabbits. The decline in hyperactivated motility was paralleled by a decrease in the average sperm curvilinear velocity (VCL) and average amplitude of lateral head displacement (AALH), but was not accompanied by a concomitant decrease in percentage of motile sperm. Pb2+ and Cd2+, at concentr","Action of metallic ions on the precocious development by rabbit sperm of motion patterns that are characteristic of hyperactivated motility Abs: BIOSIS COPYRIGHT: BIOL ABS. An earlier study demonstrated that rabbit sperm incubated for 16 hr under capacitation conditions acquire motility patterns identical to those seen in rabbit sperm capacitated in vivo. We now show that similar motion patterns develop after 0.5 hr incubation in a Trisbuffered medium, medium M. Development and decline of the motion patterns occurred in three phases each recognized by the character of the biphasic motion patterns. Hyperactivated sperm were objectively identified and quantified by a previously developed computer-directed model. The percentage of motile sperm that acquired hyperactivated motility and the period they remained in this state varied among sperm from different rabbits. The decline in hyperactivated motility was paralleled by a decrease in the average sperm curvilinear velocity (VCL) and average amplitude of lateral head displacement (AALH), but was not accompanied by a concomitant decrease in percentage of motile sperm. Pb2+ and Cd2+, at concentr"
77117,Chowdhuri et al. 2001,Effect of lead and chromium on nucleic acid and protein synthesis during sperm-zona binding in mice,"Lead and chromium are ubiquitous environmental pollutants and their effects on reproductive physiology as shown by animal experiments and human studies is well documented. The present study was conducted to ascertain the role of these metals on gamete physiology during the sperm-zona binding process, Superovulated ova and capacitated sperm from BALB/c mice were exposed to lead (0.0, 0.2, 0. 5, 1.0 and 2.0 microg/ml) or chromium (0.0, 5.0, 10.0 and 20.0 microg/ml) for 2 h in the culture medium. The sperm that became attached to the ova in the presence of these metals were scored. Synthesis of DNA, RNA and protein was assessed during this process by labelling the cells with [3H]thymidine (20 microCi/ml), [3H]uridine (50 microCi/ml) and [35S]methionine (10 microCi/ml) in the culture medium after exposure to the metals for 2 h. Our studies show a significant dose-dependent decrease in the number of sperm attaching to the ova in both exposed groups along with a decrease in the incorporation of radiolabelled thymidine, uridine and methionine. The results indicate that DNA, RNA and protein synthesis under sperm-zona binding conditions are affected by the presence of these two metals. The physiology of the gametes is altered resulting in a low frequency of sperm attachment to the ova, which in turn leads to a risk of reproductive failure.","Effect of lead and chromium on nucleic acid and protein synthesis during sperm-zona binding in mice Abs: Lead and chromium are ubiquitous environmental pollutants and their effects on reproductive physiology as shown by animal experiments and human studies is well documented. The present study was conducted to ascertain the role of these metals on gamete physiology during the sperm-zona binding process, Superovulated ova and capacitated sperm from BALB/c mice were exposed to lead (0.0, 0.2, 0. 5, 1.0 and 2.0 microg/ml) or chromium (0.0, 5.0, 10.0 and 20.0 microg/ml) for 2 h in the culture medium. The sperm that became attached to the ova in the presence of these metals were scored. Synthesis of DNA, RNA and protein was assessed during this process by labelling the cells with [3H]thymidine (20 microCi/ml), [3H]uridine (50 microCi/ml) and [35S]methionine (10 microCi/ml) in the culture medium after exposure to the metals for 2 h. Our studies show a significant dose-dependent decrease in the number of sperm attaching to the ova in both exposed groups along with a decrease in the incorporation of radiolabelled thymidine, uridine and methionine. The results indicate that DNA, RNA and protein synthesis under sperm-zona binding conditions are affected by the presence of these two metals. The physiology of the gametes is altered resulting in a low frequency of sperm attachment to the ova, which in turn leads to a risk of reproductive failure."
76205,Goodwin et al. 1981,A comparison of three guinea-pig sensitization procedures for the detection of 19 reported human contact sensitizers,"A maximization test (after Magnusson &amp; Kligman 1970), a single injection adjuvant test (SIAT) and a modified Draize test procedure for assessing contact sensitization potential in guinea-pigs have been compared for their ability to detect 19 known human contact sensitizers. The results show that the modified Draize procedure is a good screening test particularly for strong sensitizers. The maximization procedure is a very stringent test of sensitization potential, able to detect some marginal sensitizers. The sensitivity of the SIAT procedure is sufficiently similar to that of the maximization test to act as an alternative for routine testing, particularly in view of its practical advantages over the maximization procedure.","A comparison of three guinea-pig sensitization procedures for the detection of 19 reported human contact sensitizers Abs: A maximization test (after Magnusson &amp; Kligman 1970), a single injection adjuvant test (SIAT) and a modified Draize test procedure for assessing contact sensitization potential in guinea-pigs have been compared for their ability to detect 19 known human contact sensitizers. The results show that the modified Draize procedure is a good screening test particularly for strong sensitizers. The maximization procedure is a very stringent test of sensitization potential, able to detect some marginal sensitizers. The sensitivity of the SIAT procedure is sufficiently similar to that of the maximization test to act as an alternative for routine testing, particularly in view of its practical advantages over the maximization procedure."
73070,Borella and  Bargellini 1993,Effects of trace elements on immune system: results in cultured human lymphocytes,"We have studied the effects of lead, cadmium and hexavalent chromium in cultured human lymphocytes. Both the proliferative response and the generation of antibodies were evaluated, and the metal accumulation in the cells was measured. Lead added in the range of human exposure caused a significant enhancement in Ig production, which was related to the Pb concentration in the cells. An inhibitory effect on blastogenesis, was detected at Cd doses found in occupationally exposed subjects. Chromium induced reductions in both blastogenesis and Ig production in relation to its capability to enter the cells.","Effects of trace elements on immune system: results in cultured human lymphocytes Abs: We have studied the effects of lead, cadmium and hexavalent chromium in cultured human lymphocytes. Both the proliferative response and the generation of antibodies were evaluated, and the metal accumulation in the cells was measured. Lead added in the range of human exposure caused a significant enhancement in Ig production, which was related to the Pb concentration in the cells. An inhibitory effect on blastogenesis, was detected at Cd doses found in occupationally exposed subjects. Chromium induced reductions in both blastogenesis and Ig production in relation to its capability to enter the cells."
71247,Hiemstra 2002,Novel roles of protease inhibitors in infection and inflammation,"The local balance between proteinase inhibitors and proteinases determines local proteolytic activity. Various studies have demonstrated the importance of serine proteinase inhibitors in regulating the activity of serine proteinases that are released by leucocytes during inflammation. Recently it has been shown that these inhibitors may also display functions that are distinct from those associated with the inhibition of leucocyte-derived proteinases. In this review the results of selected studies focusing on three inhibitors of neutrophil elastase, i.e. alpha(1)-proteinase inhibitor, secretory leucocyte proteinase inhibitor and elafin, are presented, with the aim of illustrating their possible involvement in the regulation of inflammation, host defence against infection, tissue repair and extracellular matrix synthesis.","Novel roles of protease inhibitors in infection and inflammation Abs: The local balance between proteinase inhibitors and proteinases determines local proteolytic activity. Various studies have demonstrated the importance of serine proteinase inhibitors in regulating the activity of serine proteinases that are released by leucocytes during inflammation. Recently it has been shown that these inhibitors may also display functions that are distinct from those associated with the inhibition of leucocyte-derived proteinases. In this review the results of selected studies focusing on three inhibitors of neutrophil elastase, i.e. alpha(1)-proteinase inhibitor, secretory leucocyte proteinase inhibitor and elafin, are presented, with the aim of illustrating their possible involvement in the regulation of inflammation, host defence against infection, tissue repair and extracellular matrix synthesis."
70023,Holmes et al. 2005,Lead ions do not cause human lung cells to escape chromate-induced cytotoxicity,"Hexavalent chromium (Cr (VI)) compounds are established human lung carcinogens. Solubility plays a key role in Cr (VI) carcinogenicity, with the most potent carcinogens being water-insoluble or æparticulateÆ. Lead chromate is used as the prototypical particulate Cr (VI) compound since it is the most insoluble of these compounds. Previous work in our laboratory showed that lead chromate particles dissolve outside cells to produce chromium (Cr) and lead (Pb) ions and that the Cr ions were genotoxic. Pb has been hypothesized to play an epigenetic role in the carcinogenic activity of lead chromate, perhaps by allowing Cr-damaged cells to survive, however, this possibility has not been investigated. Accordingly, we determined the functional role of Pb and Cr ions in lead chromate-induced clonogenic survival. We found that vitamin C co-treatment eliminated Cr ion uptake, had only a slight effect on Pb ion levels, and eliminated lead chromate cytotoxicity. These data indicate that Cr ions caused the cytotoxicity. We found that lead chromate and soluble Cr (VI) induced similar amounts of cytotoxicity indicating that Pb does not play an epigenetic role and cause Cr-damaged cells to survive.","Lead ions do not cause human lung cells to escape chromate-induced cytotoxicity Abs: Hexavalent chromium (Cr (VI)) compounds are established human lung carcinogens. Solubility plays a key role in Cr (VI) carcinogenicity, with the most potent carcinogens being water-insoluble or æparticulateÆ. Lead chromate is used as the prototypical particulate Cr (VI) compound since it is the most insoluble of these compounds. Previous work in our laboratory showed that lead chromate particles dissolve outside cells to produce chromium (Cr) and lead (Pb) ions and that the Cr ions were genotoxic. Pb has been hypothesized to play an epigenetic role in the carcinogenic activity of lead chromate, perhaps by allowing Cr-damaged cells to survive, however, this possibility has not been investigated. Accordingly, we determined the functional role of Pb and Cr ions in lead chromate-induced clonogenic survival. We found that vitamin C co-treatment eliminated Cr ion uptake, had only a slight effect on Pb ion levels, and eliminated lead chromate cytotoxicity. These data indicate that Cr ions caused the cytotoxicity. We found that lead chromate and soluble Cr (VI) induced similar amounts of cytotoxicity indicating that Pb does not play an epigenetic role and cause Cr-damaged cells to survive."
69811,Naganuma et al. 1983,The interaction of selenium with various metals in vitro and in vivo,"The interaction of selenium (7782492) with various metal ions was studied in-vivo and in-vitro. Male CD-1-mice were injected intravenously with 10 micromoles per kilogram (micromol/kg) selenium-75 (14265715) (Se-75) labeled sodium-selenite (10102188) and 0 or 10micromol/kg of 24 other metal ions. Twenty four hours after administration, blood, brain, heart, lung, liver, spleen, kidney, and testis were removed and assayed for Se-75 activity. Four in-vitro reaction systems consisting of heparinized rabbit blood, rabbit blood plasma, and reduced glutathione at concentrations of 50 micromoles per milliliter or 100 nanomoles per milliliter were incubated with Se-75 labeled sodium-selenite at concentrations of 10 nanomoles per milliliter to 0.00001 molar solutions. The distribution of Se-75 activity in the plasma, erythrocytes, and water insoluble fractions was determined. Silver (7440224), monovalent copper (17493866), cadmium (7440439), mercury (7439976), lead (7439921), zinc (7440666), arsenic (7440382), bismuth (7440699), nickel (7440020), trivalent chromium (16065831), divalent platinum (22542105), gold (7440575), and palladium (7440053) ions significantly altered the distribution of selenium in mouse tissues. Manganese (7439965), silver, monovalent and divalent copper (15158119), cadmium, mercuric, lead, zinc, arsenious, divalent cobalt (22541533), nickel, hexavalent chromium (18540299), platinum, gold, thallium (22537560), and palladium ions significantly affected the in-vitro behavior of selenium. The authors conclude that interaction between selenium and metals usually occurs in animals and regulates their toxicity, physiological activity, and behavior.","The interaction of selenium with various metals in vitro and in vivo Abs: The interaction of selenium (7782492) with various metal ions was studied in-vivo and in-vitro. Male CD-1-mice were injected intravenously with 10 micromoles per kilogram (micromol/kg) selenium-75 (14265715) (Se-75) labeled sodium-selenite (10102188) and 0 or 10micromol/kg of 24 other metal ions. Twenty four hours after administration, blood, brain, heart, lung, liver, spleen, kidney, and testis were removed and assayed for Se-75 activity. Four in-vitro reaction systems consisting of heparinized rabbit blood, rabbit blood plasma, and reduced glutathione at concentrations of 50 micromoles per milliliter or 100 nanomoles per milliliter were incubated with Se-75 labeled sodium-selenite at concentrations of 10 nanomoles per milliliter to 0.00001 molar solutions. The distribution of Se-75 activity in the plasma, erythrocytes, and water insoluble fractions was determined. Silver (7440224), monovalent copper (17493866), cadmium (7440439), mercury (7439976), lead (7439921), zinc (7440666), arsenic (7440382), bismuth (7440699), nickel (7440020), trivalent chromium (16065831), divalent platinum (22542105), gold (7440575), and palladium (7440053) ions significantly altered the distribution of selenium in mouse tissues. Manganese (7439965), silver, monovalent and divalent copper (15158119), cadmium, mercuric, lead, zinc, arsenious, divalent cobalt (22541533), nickel, hexavalent chromium (18540299), platinum, gold, thallium (22537560), and palladium ions significantly affected the in-vitro behavior of selenium. The authors conclude that interaction between selenium and metals usually occurs in animals and regulates their toxicity, physiological activity, and behavior."
69336,Susa et al. 1994,Protective effects of thiol compounds on chromate-induced toxicity in vitro and in vivo,"The effects of thiol compounds (L-cysteine ethyl ester, 2,3-dimercaptosuccinic acid, or 2,3-dimercapto-1-propanesulfonic acid) on the toxicity induced by chromate (potassium dichromate) were investigated in HeLa cells and mice. Chromate-induced cytotoxicity evaluated by inhibition of cell growth and chromium content of the cells was diminished by all of the thiol compounds tested when the cells were incubated in the medium with both chromate and one of the thiol compounds. In mice injected ip with a thiol compound immediately after injection of chromate, mortality, ornithine carbamyl transferase activity in the serum, and chromium content in the liver were diminished remarkably compared with mice injected with chromate alone. These thiol compounds also caused an increase of urinary chromium excretion. These results suggest that the thiol compounds tested are useful for treating chromate-induced toxicity when they are given immediately after intake of the metal.","Protective effects of thiol compounds on chromate-induced toxicity in vitro and in vivo Abs: The effects of thiol compounds (L-cysteine ethyl ester, 2,3-dimercaptosuccinic acid, or 2,3-dimercapto-1-propanesulfonic acid) on the toxicity induced by chromate (potassium dichromate) were investigated in HeLa cells and mice. Chromate-induced cytotoxicity evaluated by inhibition of cell growth and chromium content of the cells was diminished by all of the thiol compounds tested when the cells were incubated in the medium with both chromate and one of the thiol compounds. In mice injected ip with a thiol compound immediately after injection of chromate, mortality, ornithine carbamyl transferase activity in the serum, and chromium content in the liver were diminished remarkably compared with mice injected with chromate alone. These thiol compounds also caused an increase of urinary chromium excretion. These results suggest that the thiol compounds tested are useful for treating chromate-induced toxicity when they are given immediately after intake of the metal."
69335,Witmer et al. 1994,In vivo effects of chromium,"The production of reactive oxygen species on addition of hexavalent chromium (potassium dichromate, K2Cr2O7) to lung cells in culture was studied using flow cytometer analysis. A Coulter Epics Profile II flow cytometer was used to detect the formation of reactive oxygen species after K2Cr2O7 was added to A549 cells grown to confluence. The cells were loaded with the dye, 2',7'-dichlorofluorescein diacetate, after which cellular esterases removed the acetate groups and the dye was trapped intracellularly. Reactive oxygen species oxidized the dye, with resultant fluorescence. Increased doses of Cr(VI) caused increasing fluorescence (10-fold higher than background at 200 microM). Addition of Cr(III) compounds, as the picolinate or chloride, caused no increased fluorescence. Electron paramagnetic resonance (EPR) spectroscopic studies indicated that three (as yet unidentified) spectral &quot;signals&quot; of the free radical type were formed on addition of 20, 50, 100, and 200 microM Cr(VI) to the A549 cells in suspension. Two other EPR &quot;signals&quot; with the characteristics of Cr(V) entities were seen at field values lower than the standard free radical value. Liver microsomes from male Sprague-Dawley rats treated intraperitoneally with K2Cr2O7 (130 mumole/kg every 48 hr for six treatments) had decreased activity of cytochromes P4503A1 and/or 3A2, and 2C11. Hepatic microsomes from treated female Sprague-Dawley rats, in contrast, had increased activities of these isozymes. Lung microsomes from male Sprague-Dawley rats had increased activity of P4502C11.","In vivo effects of chromium Abs: The production of reactive oxygen species on addition of hexavalent chromium (potassium dichromate, K2Cr2O7) to lung cells in culture was studied using flow cytometer analysis. A Coulter Epics Profile II flow cytometer was used to detect the formation of reactive oxygen species after K2Cr2O7 was added to A549 cells grown to confluence. The cells were loaded with the dye, 2',7'-dichlorofluorescein diacetate, after which cellular esterases removed the acetate groups and the dye was trapped intracellularly. Reactive oxygen species oxidized the dye, with resultant fluorescence. Increased doses of Cr(VI) caused increasing fluorescence (10-fold higher than background at 200 microM). Addition of Cr(III) compounds, as the picolinate or chloride, caused no increased fluorescence. Electron paramagnetic resonance (EPR) spectroscopic studies indicated that three (as yet unidentified) spectral &quot;signals&quot; of the free radical type were formed on addition of 20, 50, 100, and 200 microM Cr(VI) to the A549 cells in suspension. Two other EPR &quot;signals&quot; with the characteristics of Cr(V) entities were seen at field values lower than the standard free radical value. Liver microsomes from male Sprague-Dawley rats treated intraperitoneally with K2Cr2O7 (130 mumole/kg every 48 hr for six treatments) had decreased activity of cytochromes P4503A1 and/or 3A2, and 2C11. Hepatic microsomes from treated female Sprague-Dawley rats, in contrast, had increased activities of these isozymes. Lung microsomes from male Sprague-Dawley rats had increased activity of P4502C11."
69333,O'Brien and  Kortenkamp 1994,Chemical models important in understanding the ways in which chromate can damage DNA,"Chromate is an established human carcinogen. There have been many studies of the reactivity of chromate aimed at improving understanding of chromate toxicity. In the present paper a number of conclusions of these studies are reviewed and considered in the light of new results obtained in our laboratories. A number of hypotheses are considered; it is concluded, however, that it is impossible to reconcile the generation of strand breaks by chromate during its reduction by glutathione with any simple mechanism involving the generation of DNA lesions by free hydroxyl radicals. Kinetic, spin-trapping, and competition kinetic studies, based on a strand-breaking assay, are reported in support of this conclusion.","Chemical models important in understanding the ways in which chromate can damage DNA Abs: Chromate is an established human carcinogen. There have been many studies of the reactivity of chromate aimed at improving understanding of chromate toxicity. In the present paper a number of conclusions of these studies are reviewed and considered in the light of new results obtained in our laboratories. A number of hypotheses are considered; it is concluded, however, that it is impossible to reconcile the generation of strand breaks by chromate during its reduction by glutathione with any simple mechanism involving the generation of DNA lesions by free hydroxyl radicals. Kinetic, spin-trapping, and competition kinetic studies, based on a strand-breaking assay, are reported in support of this conclusion."
69332,da Cruz Fresco and  Kortenkamp 1994,The formation of DNA cleaving species during the reduction of chromate by ascorbate,"A detailed study of the ability of chromate in combination with ascorbate to induce DNA single-strand breaks in the absence of iron(II) and copper(II) has been carried out. In solutions containing 1 mM ascorbate and chromate in the range 0.1-1 mM extensive DNA cleavage occurred. Chromate alone or the final product of the chromate/ascorbate reaction were not responsible for the cleavage observed. Evidence is presented that an intermediate generated during the reduction of chromate is the reactive species. No strand breaks occurred upon addition of catalase, pointing to a role for peroxidic species in the steps leading to the generation of the cleaving species. The exclusion of oxygen led to a substantial decrease in the number of strand breaks. Furthermore, the formation of strand breaks declined with decreasing concentrations of phosphate in the phosphate buffers used as the incubation medium. No DNA strand breaks were induced in medium containing HEPES. These observations rule out chromium(V) as the agent directly responsible for the DNA degradation, as chromium(V) is formed during the reduction of chromate by ascorbate in HEPES buffer. Our results lead us to suggest that the DNA-damaging ability of chromate upon reduction by ascorbate arises from the activation of oxygen exacerbated by phosphate and points to a peroxo or superoxo complex involving chromium(V) or chromium(IV) as a possible candidate.","The formation of DNA cleaving species during the reduction of chromate by ascorbate Abs: A detailed study of the ability of chromate in combination with ascorbate to induce DNA single-strand breaks in the absence of iron(II) and copper(II) has been carried out. In solutions containing 1 mM ascorbate and chromate in the range 0.1-1 mM extensive DNA cleavage occurred. Chromate alone or the final product of the chromate/ascorbate reaction were not responsible for the cleavage observed. Evidence is presented that an intermediate generated during the reduction of chromate is the reactive species. No strand breaks occurred upon addition of catalase, pointing to a role for peroxidic species in the steps leading to the generation of the cleaving species. The exclusion of oxygen led to a substantial decrease in the number of strand breaks. Furthermore, the formation of strand breaks declined with decreasing concentrations of phosphate in the phosphate buffers used as the incubation medium. No DNA strand breaks were induced in medium containing HEPES. These observations rule out chromium(V) as the agent directly responsible for the DNA degradation, as chromium(V) is formed during the reduction of chromate by ascorbate in HEPES buffer. Our results lead us to suggest that the DNA-damaging ability of chromate upon reduction by ascorbate arises from the activation of oxygen exacerbated by phosphate and points to a peroxo or superoxo complex involving chromium(V) or chromium(IV) as a possible candidate."
69313,Nethercott et al. 1994,A study of chromium induced allergic contact dermatitis with 54 volunteers: Implications for environmental risk assessment,"Over the past 60 years, dose-response patch test studies by various methods have been conducted in an attempt to identify the minimum elicitation threshold (MET) concentration of hexavalent chromium (Cr(VI)) that produces an allergic response in Cr(VI) sensitive subjects. These data are not adequate, however, to provide an accurate estimate of the MET because of the variability in the patch testing techniques and the variability in diagnostic criteria used. Furthermore, the data were not reported in terms of mass of allergen per surface area of skin (mg Cr/cm2-skin), which is necessary for conducting occupational or environmental health risk assessments. Thus the purpose of this study was to determine the MET (mg allergen/cm2) for Cr(VI) and trivalent chromium (Cr(III)) by patch testing techniques. A patch test method that delivers a controlled amount of allergen per surface area of skin was used. A group of 54 Cr(VI) sensitised volunteers were patch tested with serial dilutions of Cr(VI) and Cr(III) to determine the cumulative response rate at several concentrations. The results indicate that the 10% MET for Cr(VI) based on the cumulative response was 0.089 micrograms Cr(VI)/cm2-skin. Only one of the 54 volunteers may have responded to 33 micrograms Cr(III)/cm2-skin, otherwise Cr(III) was unable to produce allergic contact dermatitis in these highly sensitive volunteers. Two supplemental studies were also conducted to assess whether the surface area of the patch and the concentration of Cr(VI) in the patch (related to patch thickness) were likely to influence the results. The data from these studies were used to assess the risk of developing allergic contact dermatitis due to contact with Cr(VI) and Cr(III) in soil. The findings indicated that soil concentrations at least as high as 450 ppm Cr(VI) and 165,000 ppm Cr(III) should not pose an allergic contact dermatitis hazard for at least 99.99% of the people in the community who might be exposed.","A study of chromium induced allergic contact dermatitis with 54 volunteers: Implications for environmental risk assessment Abs: Over the past 60 years, dose-response patch test studies by various methods have been conducted in an attempt to identify the minimum elicitation threshold (MET) concentration of hexavalent chromium (Cr(VI)) that produces an allergic response in Cr(VI) sensitive subjects. These data are not adequate, however, to provide an accurate estimate of the MET because of the variability in the patch testing techniques and the variability in diagnostic criteria used. Furthermore, the data were not reported in terms of mass of allergen per surface area of skin (mg Cr/cm2-skin), which is necessary for conducting occupational or environmental health risk assessments. Thus the purpose of this study was to determine the MET (mg allergen/cm2) for Cr(VI) and trivalent chromium (Cr(III)) by patch testing techniques. A patch test method that delivers a controlled amount of allergen per surface area of skin was used. A group of 54 Cr(VI) sensitised volunteers were patch tested with serial dilutions of Cr(VI) and Cr(III) to determine the cumulative response rate at several concentrations. The results indicate that the 10% MET for Cr(VI) based on the cumulative response was 0.089 micrograms Cr(VI)/cm2-skin. Only one of the 54 volunteers may have responded to 33 micrograms Cr(III)/cm2-skin, otherwise Cr(III) was unable to produce allergic contact dermatitis in these highly sensitive volunteers. Two supplemental studies were also conducted to assess whether the surface area of the patch and the concentration of Cr(VI) in the patch (related to patch thickness) were likely to influence the results. The data from these studies were used to assess the risk of developing allergic contact dermatitis due to contact with Cr(VI) and Cr(III) in soil. The findings indicated that soil concentrations at least as high as 450 ppm Cr(VI) and 165,000 ppm Cr(III) should not pose an allergic contact dermatitis hazard for at least 99.99% of the people in the community who might be exposed."
68737,Hanna et al. 1993,Determination of inorganic arsenic and its organic metabolites in urine by flow-injection hydride generation atomic absorption spectrometry,"A method has been developed for the determination of inorganic arsenic [As(III) and As(V)] and its organic metabolites (monomethylarsenic and dimethylarsenic) in urine by flow-injection hydride generation atomic absorption spectrometry. The nontoxic seafood-derived arsenobetaine and arsenocholine species were first separated by a solid-phase extraction procedure. The remaining sample was digested with a mixture of nitric and sulfuric acids and potassium dichromate, followed by attack with hydrogen peroxide. The resulting As(V) was reduced to As(III) with potassium iodide in hydrochloric acid before injection into the flow-injection manifold. The percentage analytical recoveries (mean +/- 95% confidence interval) of various arsenic species added to a urine specimen at 250 micrograms/L were 108 +/- 2, 112 +/- 11, 104 +/- 7, and 95 +/- 5 for As(III), As(V), monomethylarsenic, and dimethylarsenic, respectively. For the determination of arsenic in Standard Reference Material 2670 (toxic metals in human urine), results agreed with the certified value (480 +/- 100 micrograms/L). Analyses of samples for the Centre de Toxicologie du Quebec, containing seafood-derived species, demonstrated the viability of the separation procedure. Detection limits were between 0.1 and 0.2 microgram/L in the solution injected into the manifold, and precision at 10 micrograms/L was between 2% and 3% (CV). These preliminary results show that the method might be applicable to determinations of arsenic in a range of clinical urine specimens.","Determination of inorganic arsenic and its organic metabolites in urine by flow-injection hydride generation atomic absorption spectrometry Abs: A method has been developed for the determination of inorganic arsenic [As(III) and As(V)] and its organic metabolites (monomethylarsenic and dimethylarsenic) in urine by flow-injection hydride generation atomic absorption spectrometry. The nontoxic seafood-derived arsenobetaine and arsenocholine species were first separated by a solid-phase extraction procedure. The remaining sample was digested with a mixture of nitric and sulfuric acids and potassium dichromate, followed by attack with hydrogen peroxide. The resulting As(V) was reduced to As(III) with potassium iodide in hydrochloric acid before injection into the flow-injection manifold. The percentage analytical recoveries (mean +/- 95% confidence interval) of various arsenic species added to a urine specimen at 250 micrograms/L were 108 +/- 2, 112 +/- 11, 104 +/- 7, and 95 +/- 5 for As(III), As(V), monomethylarsenic, and dimethylarsenic, respectively. For the determination of arsenic in Standard Reference Material 2670 (toxic metals in human urine), results agreed with the certified value (480 +/- 100 micrograms/L). Analyses of samples for the Centre de Toxicologie du Quebec, containing seafood-derived species, demonstrated the viability of the separation procedure. Detection limits were between 0.1 and 0.2 microgram/L in the solution injected into the manifold, and precision at 10 micrograms/L was between 2% and 3% (CV). These preliminary results show that the method might be applicable to determinations of arsenic in a range of clinical urine specimens."
68190,Anwar et al. 1961,Chronic toxicity studies: III. Chronic toxicity of cadmium and chromium in dogs,,Chronic toxicity studies: III. Chronic toxicity of cadmium and chromium in dogs Abs: 
68181,Kargacin et al. 1993,Comparison of the uptake and distribution of chromate in rats and mice,"The purpose of this study was to evaluate species differences in tissue accumulation of chromium. Rats and mice were orally exposed to Cr(VI) (potassium chromate) via drinking water (8 mg/d/kg body wt for 4 or 8 wk) or by ip injection (0.3 and 0.8 mg/d/kg, for 4 or 14 d). Chromium concentrations were measured by atomic absorption spectrophotometry, and tissues were compared for exposure route and species differences. After oral exposure, irrespective of treatment duration, liver concentrations of chromium were three to four times higher in mice than rats, whereas kidney concentrations were about 50% lower. However, after ip injection, kidney and blood concentrations in rats were two- and four-fold, higher, respectively. Both rats and mice showed high values of Cr concentration in the bone. After single ip injection of Na2 51CrO4; Cr concentrations were higher in the blood of rats than mice both after 24 and 72 h. Red blood cell concentrations of Cr were also greater in rats than mice by approximately threefold, whereas white blood cell Cr concentrations were higher in mice than rats. There was also a twofold greater binding of Cr/?mol of hemoglobin in rats compared to mice. These data indicate that species differences exist for Cr metabolism and that they differ with respect to the route of exposure. These results may be owing to species differences in the reduction of Cr and different binding of Cr to hemoglobin.","Comparison of the uptake and distribution of chromate in rats and mice Abs: The purpose of this study was to evaluate species differences in tissue accumulation of chromium. Rats and mice were orally exposed to Cr(VI) (potassium chromate) via drinking water (8 mg/d/kg body wt for 4 or 8 wk) or by ip injection (0.3 and 0.8 mg/d/kg, for 4 or 14 d). Chromium concentrations were measured by atomic absorption spectrophotometry, and tissues were compared for exposure route and species differences. After oral exposure, irrespective of treatment duration, liver concentrations of chromium were three to four times higher in mice than rats, whereas kidney concentrations were about 50% lower. However, after ip injection, kidney and blood concentrations in rats were two- and four-fold, higher, respectively. Both rats and mice showed high values of Cr concentration in the bone. After single ip injection of Na2 51CrO4; Cr concentrations were higher in the blood of rats than mice both after 24 and 72 h. Red blood cell concentrations of Cr were also greater in rats than mice by approximately threefold, whereas white blood cell Cr concentrations were higher in mice than rats. There was also a twofold greater binding of Cr/?mol of hemoglobin in rats compared to mice. These data indicate that species differences exist for Cr metabolism and that they differ with respect to the route of exposure. These results may be owing to species differences in the reduction of Cr and different binding of Cr to hemoglobin."
67678,Mason et al. 1989,"Teratogenicity of combinations of sodium dichromate, sodium arsenate and copper sulphate in the rat","1. The teratogenicity of sodium dichromate (2 mg Cr/kg), sodium arsenate (5 mg As/kg) and copper sulphate (2 mg Cu/kg) in female Wistar rats was studied following the administration of the test compounds separately and in their various combinations on gestation day 8. 2. The test compounds administered separately and the combination of dichromate plus Cu2+ were non-fetotoxic and either non- or weakly teratogenic, whereas arsenate/Cu2+ was both weakly fetotoxic and teratogenic. 3. Dichromate/arsenate and dichromate/arsenate/Cu2+ caused a marked decrease in mean fetal weight and an increased incidence of fetal resorption and abnormality formation.","Teratogenicity of combinations of sodium dichromate, sodium arsenate and copper sulphate in the rat Abs: 1. The teratogenicity of sodium dichromate (2 mg Cr/kg), sodium arsenate (5 mg As/kg) and copper sulphate (2 mg Cu/kg) in female Wistar rats was studied following the administration of the test compounds separately and in their various combinations on gestation day 8. 2. The test compounds administered separately and the combination of dichromate plus Cu2+ were non-fetotoxic and either non- or weakly teratogenic, whereas arsenate/Cu2+ was both weakly fetotoxic and teratogenic. 3. Dichromate/arsenate and dichromate/arsenate/Cu2+ caused a marked decrease in mean fetal weight and an increased incidence of fetal resorption and abnormality formation."
67660,Nygren et al. 1992,"Occupational exposure to chromium, copper and arsenic during work with impregnated wood in joinery shops","CCA-impregnated timber contains copper, chromium and arsenic (CCA), and occupational exposure to wood dust as well as the CCA compounds may occur in work with such timber. Dust from commercially available impregnated wood has been found to contain hexavalent chromium, which is regarded as a carcinogen. Apart from determinations of the total amounts of the CCA compounds, specific determination of hexavalent chromium is therefore essential. Selective methods have been applied for control of the work environment in six joinery shops. The mean exposure to wood dust was found to be below 1 mg m-3. The mean airborne concentration of arsenic around various types of joinery machines was in the range from 0.54 to 3.1 micrograms m-3. No hexavalent chromium was detected in any samples and no increased concentrations of arsenic were found in urine from the workers. The presence of arsenic in the work-room air must be considered for appropriate assessment of the occupational environment in joinery shops.","Occupational exposure to chromium, copper and arsenic during work with impregnated wood in joinery shops Abs: CCA-impregnated timber contains copper, chromium and arsenic (CCA), and occupational exposure to wood dust as well as the CCA compounds may occur in work with such timber. Dust from commercially available impregnated wood has been found to contain hexavalent chromium, which is regarded as a carcinogen. Apart from determinations of the total amounts of the CCA compounds, specific determination of hexavalent chromium is therefore essential. Selective methods have been applied for control of the work environment in six joinery shops. The mean exposure to wood dust was found to be below 1 mg m-3. The mean airborne concentration of arsenic around various types of joinery machines was in the range from 0.54 to 3.1 micrograms m-3. No hexavalent chromium was detected in any samples and no increased concentrations of arsenic were found in urine from the workers. The presence of arsenic in the work-room air must be considered for appropriate assessment of the occupational environment in joinery shops."
67503,Li et al. 1992,Cytoskeletal injury induced by hexavalent chromate,,Cytoskeletal injury induced by hexavalent chromate Abs: 
67245,Camner and  Johansson 1992,Reaction of alveolar macrophages to inhaled metal aerosols,"Studies of the effects of inhaled metallic aerosols on alveolar macrophages (AMs) were discussed. The results of experiments in which rabbits were exposed to metallic nickel (7440020), chromium (7440473), cobalt (7440484), or iron (7439896) for 3 or 6 weeks were considered. Exposure to nickel caused significant accumulations of AMs in lung tissue, volume density of type-II cells, and lung phospholipid concentrations. AMs recovered by lavage were packed with surfactant like inclusions and generally had inactive smooth surfaces. The AMs showed significantly increased metabolic activity. The other metals did not significantly affect morphology or function of lavaged AMs. Studies in which rabbits were exposed to soluble aerosolized compounds of nickel, cadmium (7440439), cobalt, chromium, copper (7440508), lithium (7439932), and manganese (7439965) were discussed. Soluble nickel compounds caused effects similar to those caused by metallic nickel. Cadmium-chloride (10108642) induced significant accumulations of lymphocytes, neutrophil granulocytes, and AMs in lung tissue. Type-II cell volume density and lung phospholipid concentration were increased. AMs recovered by lavage contained increased numbers of surfactant like inclusions. Soluble cobalt caused nodulation of type-II cells. Most of the lavageable AMs had a normal appearance. A small fraction had surfactant like inclusions and a smooth surface. Soluble trivalent chromium (Cr+3) and hexavalent chromium (Cr+6) compounds induced significant accumulations of AMs in lung tissue. AMs lavaged from Cr+3 exposed animals had enlarged lysosomes with distinct inclusions and an increased number of surfactant like inclusions. Cr+6 caused fewer changes in AMs than Cr+3, enlarged lysosomes being the only noticeable changes. Soluble copper caused a slight increase in the volume density of type-II cells. Lithium and manganese did not cause any significant changes in AM morphology. The authors conclude that metal aerosols induce a range of effects in the lungs which can directly or indirectly affect AMs.","Reaction of alveolar macrophages to inhaled metal aerosols Abs: Studies of the effects of inhaled metallic aerosols on alveolar macrophages (AMs) were discussed. The results of experiments in which rabbits were exposed to metallic nickel (7440020), chromium (7440473), cobalt (7440484), or iron (7439896) for 3 or 6 weeks were considered. Exposure to nickel caused significant accumulations of AMs in lung tissue, volume density of type-II cells, and lung phospholipid concentrations. AMs recovered by lavage were packed with surfactant like inclusions and generally had inactive smooth surfaces. The AMs showed significantly increased metabolic activity. The other metals did not significantly affect morphology or function of lavaged AMs. Studies in which rabbits were exposed to soluble aerosolized compounds of nickel, cadmium (7440439), cobalt, chromium, copper (7440508), lithium (7439932), and manganese (7439965) were discussed. Soluble nickel compounds caused effects similar to those caused by metallic nickel. Cadmium-chloride (10108642) induced significant accumulations of lymphocytes, neutrophil granulocytes, and AMs in lung tissue. Type-II cell volume density and lung phospholipid concentration were increased. AMs recovered by lavage contained increased numbers of surfactant like inclusions. Soluble cobalt caused nodulation of type-II cells. Most of the lavageable AMs had a normal appearance. A small fraction had surfactant like inclusions and a smooth surface. Soluble trivalent chromium (Cr+3) and hexavalent chromium (Cr+6) compounds induced significant accumulations of AMs in lung tissue. AMs lavaged from Cr+3 exposed animals had enlarged lysosomes with distinct inclusions and an increased number of surfactant like inclusions. Cr+6 caused fewer changes in AMs than Cr+3, enlarged lysosomes being the only noticeable changes. Soluble copper caused a slight increase in the volume density of type-II cells. Lithium and manganese did not cause any significant changes in AM morphology. The authors conclude that metal aerosols induce a range of effects in the lungs which can directly or indirectly affect AMs."
67234,Aiyar et al. 1992,Reduction of chromium(VI) to chromium(V) by rat liver cytosolic and microsomal fractions: is DT-diaphorase involved,"Incubation of rat liver cytosolic or microsomal fractions with chromium(VI) led to a dramatic decrease in chromium(VI) mutagenicity, as determined by the Ames Salmonella assay using the TA100 tester strain. The cytosol-dependent decrease in chromium(VI) mutagenicity was found to be counteracted in the presence of dicumarol, an inhibitor of the cytosolic enzyme NAD(P)H:quinone oxidoreductase (DT-diaphorase). In order to determine whether DT-diaphorase is a significant factor in enzymatic reduction of chromium(VI) in rat liver tissue, cytosolic and microsomal fractions were analyzed for NAD(P)H-dependent chromium (VI) reductase activity leading to chromium(V) formation by using electron paramagnetic resonance (EPR) spectroscopy. Reaction of chromium(VI) with NADH or NADPH in the presence of either cytosolic or microsomal fractions led to the formation of stable chromium(V)--NAD(P)H complexes. When glucose 6-phosphate (G6P) was present in the reaction as part of a NADPH-generating system, stable chromium(V)--G6P complexes were formed in addition to the chromium(V)--NAD(P)H complexes. The chromium(V) complexes had g values of 1.980-1.982 and superhyperfine splitting constants of 0.8-0.9 characteristic of bis(diol)oxochromium(V) complexes. Inhibition of 90% of the cytosolic DT-diaphorase activity by dicumarol led to only partial (20-22%) inhibition of chromium(V) formation. Visible and EPR spectroscopic studies showed that purified DT-diaphorase had no detectable chromium(VI) reductase activity and did not catalyze formation of chromium(V). Inhibition of 69% of microsomal aryl hydrocarbon hydroxylase activity by ketoconazole led to partial (10%) inhibition of chromium(V) formation. These results indicate that intracellular NAD(P)H-dependent enzymatic reduction of chromium(VI) in rat liver cannot be attributed to the activity of any one enzyme in the cytosolic or microsomal fractions. DT-diaphorase appears to play an indirect role in decreasing chromium(VI)-induced mutagenicity in Salmonella, possibly through interaction with other redox active cellular components. The involvement of diols such as sugars and pyridine nucleotides in stabilizing intracellularly generated chromium(V) is discussed.","Reduction of chromium(VI) to chromium(V) by rat liver cytosolic and microsomal fractions: is DT-diaphorase involved Abs: Incubation of rat liver cytosolic or microsomal fractions with chromium(VI) led to a dramatic decrease in chromium(VI) mutagenicity, as determined by the Ames Salmonella assay using the TA100 tester strain. The cytosol-dependent decrease in chromium(VI) mutagenicity was found to be counteracted in the presence of dicumarol, an inhibitor of the cytosolic enzyme NAD(P)H:quinone oxidoreductase (DT-diaphorase). In order to determine whether DT-diaphorase is a significant factor in enzymatic reduction of chromium(VI) in rat liver tissue, cytosolic and microsomal fractions were analyzed for NAD(P)H-dependent chromium (VI) reductase activity leading to chromium(V) formation by using electron paramagnetic resonance (EPR) spectroscopy. Reaction of chromium(VI) with NADH or NADPH in the presence of either cytosolic or microsomal fractions led to the formation of stable chromium(V)--NAD(P)H complexes. When glucose 6-phosphate (G6P) was present in the reaction as part of a NADPH-generating system, stable chromium(V)--G6P complexes were formed in addition to the chromium(V)--NAD(P)H complexes. The chromium(V) complexes had g values of 1.980-1.982 and superhyperfine splitting constants of 0.8-0.9 characteristic of bis(diol)oxochromium(V) complexes. Inhibition of 90% of the cytosolic DT-diaphorase activity by dicumarol led to only partial (20-22%) inhibition of chromium(V) formation. Visible and EPR spectroscopic studies showed that purified DT-diaphorase had no detectable chromium(VI) reductase activity and did not catalyze formation of chromium(V). Inhibition of 69% of microsomal aryl hydrocarbon hydroxylase activity by ketoconazole led to partial (10%) inhibition of chromium(V) formation. These results indicate that intracellular NAD(P)H-dependent enzymatic reduction of chromium(VI) in rat liver cannot be attributed to the activity of any one enzyme in the cytosolic or microsomal fractions. DT-diaphorase appears to play an indirect role in decreasing chromium(VI)-induced mutagenicity in Salmonella, possibly through interaction with other redox active cellular components. The involvement of diols such as sugars and pyridine nucleotides in stabilizing intracellularly generated chromium(V) is discussed."
67229,Ikarashi et al. 1992,Detection of contact sensitivity of metal salts using the murine local lymph node assay,"The local lymph node assay (LLNA) is a predictive test for the detection of contact allergens. Nickel and chromium sensitization are common cases in man. However, in a previous study topical application of nickel sulfate and potassium dichromate in aqueous solution failed to induce activation in the draining lymph node. This study describes the application of LLNA to evaluate the contact sensitivity of metal salts. The metal salts were applied in dimethylsulfoxide or aqueous ethanol solution. In some experiments, the skin of the ears was gently abraded using a needle prior to application of metal salts. The ability of seven metal salts to induce lymph node cell (LNC) proliferation was compared. Nickel, cobalt, chromium and copper salts increased LNC proliferation, whereas zinc, manganese and iron salts failed to induce LNC proliferation in this assay.","Detection of contact sensitivity of metal salts using the murine local lymph node assay Abs: The local lymph node assay (LLNA) is a predictive test for the detection of contact allergens. Nickel and chromium sensitization are common cases in man. However, in a previous study topical application of nickel sulfate and potassium dichromate in aqueous solution failed to induce activation in the draining lymph node. This study describes the application of LLNA to evaluate the contact sensitivity of metal salts. The metal salts were applied in dimethylsulfoxide or aqueous ethanol solution. In some experiments, the skin of the ears was gently abraded using a needle prior to application of metal salts. The ability of seven metal salts to induce lymph node cell (LNC) proliferation was compared. Nickel, cobalt, chromium and copper salts increased LNC proliferation, whereas zinc, manganese and iron salts failed to induce LNC proliferation in this assay."
67070,Olaguibel and  Basomba 1989,Occupational asthma induced by chromium salts,"Five patients with asthma related to exposure to chromium salts, in their work area, are presented. All of them were non atopics and presented a history of contact dermatitis, with positive patch tests to potassium dichromate, previous to the onset of bronchial asthma. Solutions of K2Cr2O5 were prepared in normal saline at 0.01, 0.1 and 1 mg/ml for skin prick tests (SPT) and bronchial provocation tests (BPT). Immediate cutaneous reaction by SPT was negative for controls and patients. BPT were performed by the tidal breathing method, with positive results in all subjects. A negative response was recorded in 4 control unexposed asthmatics. An attempt to inhibit BPT with sodium cromoglycate was unsuccessful. The diversity of reactions (immediate, dual and late) registered in BPT, support that bronchial reactivity can be induced specifically by inhalation of chromium salts. The data of follow-up indicates a good prognosis, provided that patients remain out of exposure. The lack of facts suggesting an IgE-mediated reaction puts forward for consideration other pathophysiologic mechanisms.","Occupational asthma induced by chromium salts Abs: Five patients with asthma related to exposure to chromium salts, in their work area, are presented. All of them were non atopics and presented a history of contact dermatitis, with positive patch tests to potassium dichromate, previous to the onset of bronchial asthma. Solutions of K2Cr2O5 were prepared in normal saline at 0.01, 0.1 and 1 mg/ml for skin prick tests (SPT) and bronchial provocation tests (BPT). Immediate cutaneous reaction by SPT was negative for controls and patients. BPT were performed by the tidal breathing method, with positive results in all subjects. A negative response was recorded in 4 control unexposed asthmatics. An attempt to inhibit BPT with sodium cromoglycate was unsuccessful. The diversity of reactions (immediate, dual and late) registered in BPT, support that bronchial reactivity can be induced specifically by inhalation of chromium salts. The data of follow-up indicates a good prognosis, provided that patients remain out of exposure. The lack of facts suggesting an IgE-mediated reaction puts forward for consideration other pathophysiologic mechanisms."
66689,Johansson et al. 1992,Rabbit lung after combined exposure to soluble cobalt and trivalent chromium,"Eight rabbits were exposed to 0.7 ± 0.4 mg/m3 Co2+ as CoCl2 and 1.2 ± 0.7 mg/m3 Cr3+ as Cr(NO3)3 (group Co + Cr), eight to 0.6 ± 0.5 mg/m3 Co2+ (group Co), and eight to filtered air (control group), for 4 months, 5 days/week, and 6 hr/day. All rabbits in group Co + Cr and group Co showed nodular aggregation of alveolar epithelial type II cells. Volume density of the type II cells was significantly higher in group Co + Cr than in group Co and the control group. There was intraalveolar macrophage accumulation in seven rabbits in group Co + Cr, one in group Co, and one in the control group. In lavage fluid the numbers of macrophages and the percentage of these cells with smooth surface and intracellular surfactant-like inclusions were more increased in group Co + Cr than in group Co as were oxidative metabolic and phagocytic activities of the macrophages. Total phospholipids, phosphatidylcholines, and especially 1,2-dipalmitoylphosphatidylcholine were markedly increased in group Co + Cr whereas only 1,2-dipalmitoylphosphatidylcholine was slightly increased in group Co. One mechanism behind the high amount of surfactant phospholipids in group Co + Cr seems to be an enhanced production of surfactant by the type II cells. Another mechanism is probably that Cr3+ reduces the capacity of alveolar macrophages to catabolize surfactant. The results imply that it is important to investigate effects of combinations of cobalt and chromium in the occupational environment.","Rabbit lung after combined exposure to soluble cobalt and trivalent chromium Abs: Eight rabbits were exposed to 0.7 ± 0.4 mg/m3 Co2+ as CoCl2 and 1.2 ± 0.7 mg/m3 Cr3+ as Cr(NO3)3 (group Co + Cr), eight to 0.6 ± 0.5 mg/m3 Co2+ (group Co), and eight to filtered air (control group), for 4 months, 5 days/week, and 6 hr/day. All rabbits in group Co + Cr and group Co showed nodular aggregation of alveolar epithelial type II cells. Volume density of the type II cells was significantly higher in group Co + Cr than in group Co and the control group. There was intraalveolar macrophage accumulation in seven rabbits in group Co + Cr, one in group Co, and one in the control group. In lavage fluid the numbers of macrophages and the percentage of these cells with smooth surface and intracellular surfactant-like inclusions were more increased in group Co + Cr than in group Co as were oxidative metabolic and phagocytic activities of the macrophages. Total phospholipids, phosphatidylcholines, and especially 1,2-dipalmitoylphosphatidylcholine were markedly increased in group Co + Cr whereas only 1,2-dipalmitoylphosphatidylcholine was slightly increased in group Co. One mechanism behind the high amount of surfactant phospholipids in group Co + Cr seems to be an enhanced production of surfactant by the type II cells. Another mechanism is probably that Cr3+ reduces the capacity of alveolar macrophages to catabolize surfactant. The results imply that it is important to investigate effects of combinations of cobalt and chromium in the occupational environment."
65882,Migliore and  De Nicola Giudici 1990,"Toxicity of heavy metals to Asellus aquaticus L (Crustacea, Isopoda)","BIOSIS COPYRIGHT: BIOL ABS. Effects of heavy metals on the isopod Asellus aquaticus (L.) are studied by static toxicity tests. Results demonstrate that the species is sensitive to Cd+2, Cr+6, Cu+2, Fe+3, Hg+2, Ni+2, Pb+2 and Zn+2, but the toxicity of each metal is different. Differences are also found between adults and between adults and juveniles. The comparative analysis of all data on the toxicity has been performed on the concentrations of metal ions and not on metal compound concentrations. Criteria for establishing water quality in order to guarantee protection of the environment are discussed.","Toxicity of heavy metals to Asellus aquaticus L (Crustacea, Isopoda) Abs: BIOSIS COPYRIGHT: BIOL ABS. Effects of heavy metals on the isopod Asellus aquaticus (L.) are studied by static toxicity tests. Results demonstrate that the species is sensitive to Cd+2, Cr+6, Cu+2, Fe+3, Hg+2, Ni+2, Pb+2 and Zn+2, but the toxicity of each metal is different. Differences are also found between adults and between adults and juveniles. The comparative analysis of all data on the toxicity has been performed on the concentrations of metal ions and not on metal compound concentrations. Criteria for establishing water quality in order to guarantee protection of the environment are discussed."
65736,Macdonald et al. 1988,Acute toxicities of eleven metals to early life-history stages of the yellow crab Cancer anthonyi,Biosis copyright: biol abs. rrm embryo prezoeae environmental contamination mortality sediment benthic habitat,Acute toxicities of eleven metals to early life-history stages of the yellow crab Cancer anthonyi Abs: Biosis copyright: biol abs. rrm embryo prezoeae environmental contamination mortality sediment benthic habitat
64434,Khangarot and  Ray 1989,Sensitivity of midge larvae of Chironomus tentans Fabricius (Diptera Chironomidae) to heavy metals,BIOSIS COPYRIGHT: BIOL ABS. RRM WATER POLLUTION TOXICITY,Sensitivity of midge larvae of Chironomus tentans Fabricius (Diptera Chironomidae) to heavy metals Abs: BIOSIS COPYRIGHT: BIOL ABS. RRM WATER POLLUTION TOXICITY
64344,Vial and  Descotes 1994,Contact sensitization assays in guinea-pigs: Are they predictive of the potential for systemic allergic reactions?,"Guinea-pig assays have been used extensively to detect contact sensitizers. In contrast, almost no reliable assays are available to detect the potential for low-molecular-weight drugs and chemicals to induce systemic allergic reactions in humans. Based on clinical data, and, to some extent, on recent immunological findings, it is proposed that guinea-pig assays can predict the hazard for systemic allergic reactions in man. Seventy drugs and chemicals were compared from published results in guinea-pig assays and in the clinic. A close correlation was found with 43 substances and a relatively good one with 16 substances. Conflicting results were found with 11 substances only. However, substances known to induce systemic allergic reactions in man were all detected as weak sensitizers, at least in guinea-pigs. Guinea-pig contact sensitization assays may therefore prove useful until more suitable and specific assays are available to predict the risk for systemic allergic rea","Contact sensitization assays in guinea-pigs: Are they predictive of the potential for systemic allergic reactions? Abs: Guinea-pig assays have been used extensively to detect contact sensitizers. In contrast, almost no reliable assays are available to detect the potential for low-molecular-weight drugs and chemicals to induce systemic allergic reactions in humans. Based on clinical data, and, to some extent, on recent immunological findings, it is proposed that guinea-pig assays can predict the hazard for systemic allergic reactions in man. Seventy drugs and chemicals were compared from published results in guinea-pig assays and in the clinic. A close correlation was found with 43 substances and a relatively good one with 16 substances. Conflicting results were found with 11 substances only. However, substances known to induce systemic allergic reactions in man were all detected as weak sensitizers, at least in guinea-pigs. Guinea-pig contact sensitization assays may therefore prove useful until more suitable and specific assays are available to predict the risk for systemic allergic rea"
64158,Kapu and  Schaeffer 1991,Planarians in toxicology: responses of asexual Dugesia dorotocephala to selected metals,Biosis copyright: biol abs. rrm heavy metal toxicity freshwater pollution bioindicator methods invertebrate,Planarians in toxicology: responses of asexual Dugesia dorotocephala to selected metals Abs: Biosis copyright: biol abs. rrm heavy metal toxicity freshwater pollution bioindicator methods invertebrate
63922,Paustenbach et al. 1991,The health hazards posed by chromium-contaminated soils in residential and industrial areas: conclusions of an expert panel,"Between 1905 and 1971, over 2 million tons of residue from chromite ore processing was generated in Hudson County, New Jersey, of which substantial amounts were used as fill and tank diking. A panel of medical, toxicology, and risk assessment experts was convened in early 1990 to evaluate the potential health hazards posed by the resulting chromium contaminated soil. The Panel concluded that soils containing concentrations of 75 ppm hexavalent chromium [Cr(VI)] and 1000 ppm total chromium compounds (about 95% was trivalent chromium [Cr(III)]) did not pose a significant health hazard to nearby residents and workers. They also determined that exposure to chromium from Hudson County sites posed a negligible cancer hazard to residents. Using risk assessment methods, the Panel estimated that the plausible incremental cancer risk to individuals at residential sites would be substantially less than 1 in 1,000,000. The average measured levels of airborne Cr(VI) at typical industrial sites were more than 1000-fold lower than the current OSHA Permissible Exposure Limit (PEL). The maximum plausible increased cancer risk for an average worker at a dusty industrial site was estimated to be less than 1 in 100,000. The Panel also concluded that chromium-containing crystals, which have occasionally been found in Hudson County buildings, do not pose a significant hazard. However, they suggested that were the concentration to exceed 5000 ppm Cr(VI) in the crystals, site-specific health risk assessments would be conducted and remediation considered. The Panel evaluated the dermal hazard posed by chromium-contaminated soil and acknowledged that there is a small group of persons (approximately 0.1% of the United States population) who currently have a dermal sensitization to Cr(VI) primarily through occupational exposure. Based on published studies of human volunteers, the Panel concluded that a small percentage (less than 5%) of persons already sensitized may respond to Cr(VI) in solution at concentrations above 35 ppm. They decided that a much higher concentration in soil, perhaps 350 ppm Cr(VI), would be necessary to elicit dermatitis because only a fraction of the chromium in soil is soluble. The Panel concluded that it was highly unlikely (if not impossible) for a person to become dermally sensitized to Cr(VI) or Cr(III) at the soil concentrations found in most areas in Hudson County.(ABSTRACT TRUNCATED AT 400 WORDS)","The health hazards posed by chromium-contaminated soils in residential and industrial areas: conclusions of an expert panel Abs: Between 1905 and 1971, over 2 million tons of residue from chromite ore processing was generated in Hudson County, New Jersey, of which substantial amounts were used as fill and tank diking. A panel of medical, toxicology, and risk assessment experts was convened in early 1990 to evaluate the potential health hazards posed by the resulting chromium contaminated soil. The Panel concluded that soils containing concentrations of 75 ppm hexavalent chromium [Cr(VI)] and 1000 ppm total chromium compounds (about 95% was trivalent chromium [Cr(III)]) did not pose a significant health hazard to nearby residents and workers. They also determined that exposure to chromium from Hudson County sites posed a negligible cancer hazard to residents. Using risk assessment methods, the Panel estimated that the plausible incremental cancer risk to individuals at residential sites would be substantially less than 1 in 1,000,000. The average measured levels of airborne Cr(VI) at typical industrial sites were more than 1000-fold lower than the current OSHA Permissible Exposure Limit (PEL). The maximum plausible increased cancer risk for an average worker at a dusty industrial site was estimated to be less than 1 in 100,000. The Panel also concluded that chromium-containing crystals, which have occasionally been found in Hudson County buildings, do not pose a significant hazard. However, they suggested that were the concentration to exceed 5000 ppm Cr(VI) in the crystals, site-specific health risk assessments would be conducted and remediation considered. The Panel evaluated the dermal hazard posed by chromium-contaminated soil and acknowledged that there is a small group of persons (approximately 0.1% of the United States population) who currently have a dermal sensitization to Cr(VI) primarily through occupational exposure. Based on published studies of human volunteers, the Panel concluded that a small percentage (less than 5%) of persons already sensitized may respond to Cr(VI) in solution at concentrations above 35 ppm. They decided that a much higher concentration in soil, perhaps 350 ppm Cr(VI), would be necessary to elicit dermatitis because only a fraction of the chromium in soil is soluble. The Panel concluded that it was highly unlikely (if not impossible) for a person to become dermally sensitized to Cr(VI) or Cr(III) at the soil concentrations found in most areas in Hudson County.(ABSTRACT TRUNCATED AT 400 WORDS)"
63728,Taylor 1966,The relationship of mortality and duration of employment as reflected by a cohort of chromate workers,"A study of chromate workers is reported in which the group was followed over a period of 24 years, using records of Old Age and Survivors Disability Insurance. Mortality data were obtained through death certificates. The findings reported are consonant with previous studies on the relationship between health and employment in the chromate industry. Questions are raised concerning the value of the kind of record used in this study and the possibility of assessing the validity of the method in other areas.","The relationship of mortality and duration of employment as reflected by a cohort of chromate workers Abs: A study of chromate workers is reported in which the group was followed over a period of 24 years, using records of Old Age and Survivors Disability Insurance. Mortality data were obtained through death certificates. The findings reported are consonant with previous studies on the relationship between health and employment in the chromate industry. Questions are raised concerning the value of the kind of record used in this study and the possibility of assessing the validity of the method in other areas."
63725,U.S. EPA 1990,Noncarcinogenic effects of chromium: update to health assessment document,,Noncarcinogenic effects of chromium: update to health assessment document Abs: 
63722,U.S. EPA 1984,Health effects assessment for hexavalent chromium,"In order to place to risk assessment evaluation in proper context, refer to the preface of this document. The preface outlines limitations applicable to all documents of this series as well as the appropriate interpretation and use of the quantitative estimates presented. Chromium exposure has been shown to contribute to increased incidence of respiratory cancers in occupationally exposed workers. The particular form(s) of chromium responsible is not clear. Increases in cancer incidence in experimental animals following chromium inhalation has not been demonstrated. However, intrapleural and intrabronchial implantation of hexavalent chromium compounds has resulted in tumors at the site of implantation. Hexavalent chromium has been shown to be mutagenic in bacterial systems. Using human epidemiological data, a unit risk of 41 (mg/kg/day) has been estimated for inhalation exposure. Data are not available to assess the potential carcinogenicity of hexavalant chromium following oral exposure. Data are inadequate to consider chromium as a carcinogen by the oral route. Using data from a 1-year rat drinking water exposure study, an oral AIC of 0.35 mg/day is estimated. Environmental chemistry and fate. In the hexavalent state, chromium exists as oxo species that are strongly oxidizing. In solution, hexavalent chromium exists as hydrochromate, chromate and dichromate ionic species. The proportion of each ion in solution is pH dependent. In basic and neutral pH, the chromate form predominate. As the pH is lowered (6.0 to 6.2), the hydrochromate concentration increases. At very low pH, the dichromate species predominate. The primary sources of hexavalent chromium in the atmosphere probably are chromate chemicals used as rust inhibitors in cooling towers and emitted as mists, particulate matter emitted during manufacture and use of metal chromates, and chromic acid mist from the plating industry. Both hexavalent and trivalent chromium are removed from air by atmospheric fallout and precipitation. The atmospheric half-life for the physical removal mechanism is expected to depend on the particle size and particle density. Chromium particles of small aerodynamic diameter (<10 um) may remain airborne for a long period. Hexavalent chromium may exist in aquatic media as water soluble complex anions and may persist in water for a long time. Hexavalent chromium is a moderately strong oxidizing agent and may react with organic matter or other reducing agents to form trivalent chromium. The trivalent chromium will eventually be precipitated as CrO3 x xH2O. Therefore, in surface water rich in organic content, hexavalent chromium will exhibit a much shorter lifetime. Any hexavalent chromium in soil is expected to be reduced to trivalent chromium by the organic matter in soil. The primary processes by which the converted trivalent chromium is lost from soil are aerial transport through aerosol formation and surface water transport through runoff. Very little chromium is leached from soil because it is present as insoluble CrO3 x xH2O. The BCF for hexavalent chromium in fish muscle appears to be <1.0, but values of 125 and 192 were obtained for oyster and blue mussel, respectively.","Health effects assessment for hexavalent chromium Abs: In order to place to risk assessment evaluation in proper context, refer to the preface of this document. The preface outlines limitations applicable to all documents of this series as well as the appropriate interpretation and use of the quantitative estimates presented. Chromium exposure has been shown to contribute to increased incidence of respiratory cancers in occupationally exposed workers. The particular form(s) of chromium responsible is not clear. Increases in cancer incidence in experimental animals following chromium inhalation has not been demonstrated. However, intrapleural and intrabronchial implantation of hexavalent chromium compounds has resulted in tumors at the site of implantation. Hexavalent chromium has been shown to be mutagenic in bacterial systems. Using human epidemiological data, a unit risk of 41 (mg/kg/day) has been estimated for inhalation exposure. Data are not available to assess the potential carcinogenicity of hexavalant chromium following oral exposure. Data are inadequate to consider chromium as a carcinogen by the oral route. Using data from a 1-year rat drinking water exposure study, an oral AIC of 0.35 mg/day is estimated. Environmental chemistry and fate. In the hexavalent state, chromium exists as oxo species that are strongly oxidizing. In solution, hexavalent chromium exists as hydrochromate, chromate and dichromate ionic species. The proportion of each ion in solution is pH dependent. In basic and neutral pH, the chromate form predominate. As the pH is lowered (6.0 to 6.2), the hydrochromate concentration increases. At very low pH, the dichromate species predominate. The primary sources of hexavalent chromium in the atmosphere probably are chromate chemicals used as rust inhibitors in cooling towers and emitted as mists, particulate matter emitted during manufacture and use of metal chromates, and chromic acid mist from the plating industry. Both hexavalent and trivalent chromium are removed from air by atmospheric fallout and precipitation. The atmospheric half-life for the physical removal mechanism is expected to depend on the particle size and particle density. Chromium particles of small aerodynamic diameter (<10 um) may remain airborne for a long period. Hexavalent chromium may exist in aquatic media as water soluble complex anions and may persist in water for a long time. Hexavalent chromium is a moderately strong oxidizing agent and may react with organic matter or other reducing agents to form trivalent chromium. The trivalent chromium will eventually be precipitated as CrO3 x xH2O. Therefore, in surface water rich in organic content, hexavalent chromium will exhibit a much shorter lifetime. Any hexavalent chromium in soil is expected to be reduced to trivalent chromium by the organic matter in soil. The primary processes by which the converted trivalent chromium is lost from soil are aerial transport through aerosol formation and surface water transport through runoff. Very little chromium is leached from soil because it is present as insoluble CrO3 x xH2O. The BCF for hexavalent chromium in fish muscle appears to be <1.0, but values of 125 and 192 were obtained for oyster and blue mussel, respectively."
63721,Trivedi et al. 1989,Embryotoxicity and fetotoxicity of orally administered hexavalent chromium in mice,"The embryotoxic and fetotoxic potential of hexavalent chromium (Cr+6) in mice was investigated by administering 250, 500, and 1000 ppm of potassium dichromate daily through drinking water during the entire gestation period. An increase in embryonic deaths was observed; however, in the mothers treated with the highest dose, there was complete absence of implantation sites. No major abnormality was observed in the fetuses except that Cr+6 exposure increased the incidences and types of external and skeletal malformations. It is concluded that oral exposure to Cr+6 causes dose-dependent embryolethal effects in mice.","Embryotoxicity and fetotoxicity of orally administered hexavalent chromium in mice Abs: The embryotoxic and fetotoxic potential of hexavalent chromium (Cr+6) in mice was investigated by administering 250, 500, and 1000 ppm of potassium dichromate daily through drinking water during the entire gestation period. An increase in embryonic deaths was observed; however, in the mothers treated with the highest dose, there was complete absence of implantation sites. No major abnormality was observed in the fetuses except that Cr+6 exposure increased the incidences and types of external and skeletal malformations. It is concluded that oral exposure to Cr+6 causes dose-dependent embryolethal effects in mice."
63719,Steffee and  Baetjer 1965,"Histopathologic effects of chromate chemicals: Report of studies in rabbits, guinea pigs, rats, and mice",,"Histopathologic effects of chromate chemicals: Report of studies in rabbits, guinea pigs, rats, and mice Abs: "
63716,Nettesheim et al. 1971,"Effect of calcium chromate dust, influenza virus, and 100 R whole-body X radiation on lung tumor incidence in mice","Chronic inhalation exposure of C57BL/6 mice to calcium chromate(CaCrO4) dustresultedin a fourfold increasein pulmonary adenoma incidence. Acute exposure to 100 R whole-body X radiation caused a similar increase in tumor incidence. The effects of the two tumorigenic insults were not additive. PRe influenza virus infection suppressed spontaneous as well as X ray- and CaCrO4-induced pulmonary adenoma development. The overall lung adenoma incidence was higher in males than in females. CaCrO4 also induced other pathological changes in the respiratory tract, such as epithelial necrosis and regenerative hyperplasia in the conducting airways, alveolar “bronchiolization,” alveolar proteinosis, and emphysema-like changes, and suppressed the lymphoma incidence.","Effect of calcium chromate dust, influenza virus, and 100 R whole-body X radiation on lung tumor incidence in mice Abs: Chronic inhalation exposure of C57BL/6 mice to calcium chromate(CaCrO4) dustresultedin a fourfold increasein pulmonary adenoma incidence. Acute exposure to 100 R whole-body X radiation caused a similar increase in tumor incidence. The effects of the two tumorigenic insults were not additive. PRe influenza virus infection suppressed spontaneous as well as X ray- and CaCrO4-induced pulmonary adenoma development. The overall lung adenoma incidence was higher in males than in females. CaCrO4 also induced other pathological changes in the respiratory tract, such as epithelial necrosis and regenerative hyperplasia in the conducting airways, alveolar “bronchiolization,” alveolar proteinosis, and emphysema-like changes, and suppressed the lymphoma incidence."
63715,Moller et al. 1986,Delayed anaphylactoid reaction in a worker exposed to chromium,"A 29-year-old male welder reported systemic reactions after exposure to chromium. Inhalation challenge testing to 29 micrograms/m3 of sodium chromate aerosol resulted in late appearing systemic urticaria, angioedema, and severe bronchospasm that occurred at the same time as a threefold rise in plasma histamine. A direct leukocyte inhibitory factor test to 5.5 X 10(-6)mol/L Na2CrO4 was positive. Although the mechanism of this reaction is unknown, the positive leukocyte inhibitory factor and the general acceptance of hexavalent chromium as a contact skin sensitizer suggest that cell-mediated mechanisms could be involved.","Delayed anaphylactoid reaction in a worker exposed to chromium Abs: A 29-year-old male welder reported systemic reactions after exposure to chromium. Inhalation challenge testing to 29 micrograms/m3 of sodium chromate aerosol resulted in late appearing systemic urticaria, angioedema, and severe bronchospasm that occurred at the same time as a threefold rise in plasma histamine. A direct leukocyte inhibitory factor test to 5.5 X 10(-6)mol/L Na2CrO4 was positive. Although the mechanism of this reaction is unknown, the positive leukocyte inhibitory factor and the general acceptance of hexavalent chromium as a contact skin sensitizer suggest that cell-mediated mechanisms could be involved."
63711,Lindberg and  Vesterberg 1983,"Urinary excretion of proteins in chromeplaters, exchromeplaters and referents","Urinary excretion of proteins in chromeplaters, exchromeplaters and referents. Scand j work environ health 9 (1983) 505-510. beta 2-microglobulin was measured in the urine of 24 presently exposed chromeplaters, 27 previously exposed chromeplaters, and 37 referents. The concentration of beta 2-microglobulin and the number of ""elevated"" values (greater than 0.30 mg/l) was higher in the presently exposed group than in the referents. Within the presently exposed group there was a dose-effect relation between the concentration of hexavalent chromium in air and the number of elevated values of urinary beta 2-microglobulin. However, no difference between the previously exposed chromeplaters and the referents could be demonstrated regarding urinary beta 2-microglobulin. There were no indications that the exposure could raise the excretion of albumin in urine. The results seem to indicate an acute effect on the kidney tubules, which is reversible even in workers who have had a relatively high exposure to chromic acid.","Urinary excretion of proteins in chromeplaters, exchromeplaters and referents Abs: Urinary excretion of proteins in chromeplaters, exchromeplaters and referents. Scand j work environ health 9 (1983) 505-510. beta 2-microglobulin was measured in the urine of 24 presently exposed chromeplaters, 27 previously exposed chromeplaters, and 37 referents. The concentration of beta 2-microglobulin and the number of ""elevated"" values (greater than 0.30 mg/l) was higher in the presently exposed group than in the referents. Within the presently exposed group there was a dose-effect relation between the concentration of hexavalent chromium in air and the number of elevated values of urinary beta 2-microglobulin. However, no difference between the previously exposed chromeplaters and the referents could be demonstrated regarding urinary beta 2-microglobulin. There were no indications that the exposure could raise the excretion of albumin in urine. The results seem to indicate an acute effect on the kidney tubules, which is reversible even in workers who have had a relatively high exposure to chromic acid."
63710,Lindberg and  Hedenstierna 1983,"Chrome plating: Symptoms, findings in the upper airways, and effects on lung function","Respiratory symptoms, lung function, and changes in the nasal septum were noted for 100 subjects exposed to chrome plating. The findings were compared with those of 119 nonexposed controls, studied with identical techniques, as well as with data in the literature. Complaints of nasal irritation were common among subjects exposed to a daily average that exceeded 1 microgram/m3 of chromic acid, while the frequency of chronic bronchitis was similar to that in different control series. Nasal septal ulceration and perforation were seen in two-thirds of the subjects exposed to peak levels of 20 micrograms/m3 or more. Both forced vital capacity and forced expired volume in 1 sec were reduced by 0.2 L. The forced midexpiratory flow diminished by 0.4 L/sec from Monday morning to Thursday afternoon in subjects exposed to a daily average of 2 micrograms/m3 or more chromic acid, but there was no clear correlation with short-term high exposure. Subjects exposed to lower levels showed no significant changes. Data collected on Monday morning (i.e., after 2 days without exposure) did not differ significantly from reference values. It is concluded that an 8-hr mean exposure exceeding 2 micrograms/m3 may cause a transient decrease in lung function, and that short-term exposure to at least 20 micrograms/m3 may cause septal ulceration and perforation.","Chrome plating: Symptoms, findings in the upper airways, and effects on lung function Abs: Respiratory symptoms, lung function, and changes in the nasal septum were noted for 100 subjects exposed to chrome plating. The findings were compared with those of 119 nonexposed controls, studied with identical techniques, as well as with data in the literature. Complaints of nasal irritation were common among subjects exposed to a daily average that exceeded 1 microgram/m3 of chromic acid, while the frequency of chronic bronchitis was similar to that in different control series. Nasal septal ulceration and perforation were seen in two-thirds of the subjects exposed to peak levels of 20 micrograms/m3 or more. Both forced vital capacity and forced expired volume in 1 sec were reduced by 0.2 L. The forced midexpiratory flow diminished by 0.4 L/sec from Monday morning to Thursday afternoon in subjects exposed to a daily average of 2 micrograms/m3 or more chromic acid, but there was no clear correlation with short-term high exposure. Subjects exposed to lower levels showed no significant changes. Data collected on Monday morning (i.e., after 2 days without exposure) did not differ significantly from reference values. It is concluded that an 8-hr mean exposure exceeding 2 micrograms/m3 may cause a transient decrease in lung function, and that short-term exposure to at least 20 micrograms/m3 may cause septal ulceration and perforation."
63709,Lee et al. 1988,Effects of inhaled chromium dioxide dust on rats exposed for two years,"Rats were exposed by inhalation to chromium dioxide (CrO2) dust at design concentrations of 0, 0.5 mg/m3 (stabilized and unstabilized, respectively), or 25 mg/m3 (stabilized) for 6 hr/day, 5 days/week for 2 years. No dust-exposure-related pathological changes other than lung lesions were observed in all exposed rats. There were no significant differences in pulmonary responses between unstabilized and stabilized CrO2 at the 0.5 mg/m3 exposure level. The lungs showed minute dust deposition in the alveoli adjacent to the alveolar ducts, but maintained an intact general architecture. The pulmonary responses satisfied the biological criteria for a nuisance dust. At 25 mg/m3, dust deposition was sharply confined to the alveoli in the alveolar duct region. Alveolar walls enclosing dust-laden macrophage (dust cell) aggregates were thickened with hyperplastic Type II pneumocytes and slightly collagenized fibrosis. Alveoli adjacent to the terminal bronchioles were lined with bronchiolar epithelium (alveolar bronchiolarization). In addition, lungs showed foamy macrophage response, cholesterol granulomas, alveolar proteinosis, and minute fibrotic pleurisy. These pulmonary lesions occurred predominantly in female rats. Of 108 female rats, 6 developed keratin cysts and 2 had cystic keratinizing squamous cell carcinoma (CKSCC). None of 106 male rats had either a keratin cyst or a CKSCC. The lung tumors developed from metaplastic squamous cells in the areas of alveolar bronchiolarization at the alveolar duct region. The lung tumors were well differentiated and devoid of characteristics of true malignancy. The CKSCC is an experimentally induced, unique tumor type and is different from the type of spontaneous lung tumor seen in man or animals. The relevance to man of this type of lung tumor appears to be negligible.","Effects of inhaled chromium dioxide dust on rats exposed for two years Abs: Rats were exposed by inhalation to chromium dioxide (CrO2) dust at design concentrations of 0, 0.5 mg/m3 (stabilized and unstabilized, respectively), or 25 mg/m3 (stabilized) for 6 hr/day, 5 days/week for 2 years. No dust-exposure-related pathological changes other than lung lesions were observed in all exposed rats. There were no significant differences in pulmonary responses between unstabilized and stabilized CrO2 at the 0.5 mg/m3 exposure level. The lungs showed minute dust deposition in the alveoli adjacent to the alveolar ducts, but maintained an intact general architecture. The pulmonary responses satisfied the biological criteria for a nuisance dust. At 25 mg/m3, dust deposition was sharply confined to the alveoli in the alveolar duct region. Alveolar walls enclosing dust-laden macrophage (dust cell) aggregates were thickened with hyperplastic Type II pneumocytes and slightly collagenized fibrosis. Alveoli adjacent to the terminal bronchioles were lined with bronchiolar epithelium (alveolar bronchiolarization). In addition, lungs showed foamy macrophage response, cholesterol granulomas, alveolar proteinosis, and minute fibrotic pleurisy. These pulmonary lesions occurred predominantly in female rats. Of 108 female rats, 6 developed keratin cysts and 2 had cystic keratinizing squamous cell carcinoma (CKSCC). None of 106 male rats had either a keratin cyst or a CKSCC. The lung tumors developed from metaplastic squamous cells in the areas of alveolar bronchiolarization at the alveolar duct region. The lung tumors were well differentiated and devoid of characteristics of true malignancy. The CKSCC is an experimentally induced, unique tumor type and is different from the type of spontaneous lung tumor seen in man or animals. The relevance to man of this type of lung tumor appears to be negligible."
63708,Johansson et al. 1986,Rabbit alveolar macrophages after inhalation of hexa- and trivalent chromium,"Rabbits inhaled aerosols of hexavalent chromium (Na2CrO4) and trivalent chromium (Cr(NO3)3) at concentrations of 0.9 and 0.6 mg/m3 of the metal, respectively, for 4-6 weeks (5 days/week and 6 hr/day). Significantly more macrophages were obtained from the lungs of rabbits exposed to Cr(VI) but not from rabbits exposed to Cr(III) as compared with the controls. Macrophages from rabbits exposed to Cr(III) showed several conspicuous changes. About one-third of the macrophages contained round dark inclusions, 0.5-1.5 micron diameter, rich in chromium. Most cells had very large lysosomes which contained membranous fragments of different sizes surrounded by a more homogeneous matrix. Laminated inclusions similar to the lamellar bodies in the type II cells increased in number as did the percentage of cells with a smooth cell surface. Also macrophages from rabbits exposed to Cr(VI) showed morphological changes. The most pronounced one was enlarged lysosomes which contained short lamellae and electron-dense patchy inclusions. Only Cr(III) produced functional changes of the macrophages. The metabolic activity measured by reduction of nitroblue tetrazolium was increased and the phagocytic activity reduced.","Rabbit alveolar macrophages after inhalation of hexa- and trivalent chromium Abs: Rabbits inhaled aerosols of hexavalent chromium (Na2CrO4) and trivalent chromium (Cr(NO3)3) at concentrations of 0.9 and 0.6 mg/m3 of the metal, respectively, for 4-6 weeks (5 days/week and 6 hr/day). Significantly more macrophages were obtained from the lungs of rabbits exposed to Cr(VI) but not from rabbits exposed to Cr(III) as compared with the controls. Macrophages from rabbits exposed to Cr(III) showed several conspicuous changes. About one-third of the macrophages contained round dark inclusions, 0.5-1.5 micron diameter, rich in chromium. Most cells had very large lysosomes which contained membranous fragments of different sizes surrounded by a more homogeneous matrix. Laminated inclusions similar to the lamellar bodies in the type II cells increased in number as did the percentage of cells with a smooth cell surface. Also macrophages from rabbits exposed to Cr(VI) showed morphological changes. The most pronounced one was enlarged lysosomes which contained short lamellae and electron-dense patchy inclusions. Only Cr(III) produced functional changes of the macrophages. The metabolic activity measured by reduction of nitroblue tetrazolium was increased and the phagocytic activity reduced."
63707,Johansson et al. 1986,Rabbit lung after inhalation of hexa- and trivalent chromium,"Lung tissue from rabbits exposed to Cr(VI) (18540299) or Cr(III) (16065831) was examined by light and electron microscopy with special reference to general morphology, volume density of alveolar type 1 cells, and lung content of phospholipids. The effects of the chromium (7440473) compounds were compared with those of other metal ions, studied under similar experimental conditions. Twenty-four apparently healthy male rabbits were exposed to 0.6 +/0.4mg/m3 trivalent chromium-nitrate (13548384) or 0.9mg/m3 hexavalent disodium-chromate for 4 to 6 weeks (5 days/week and 6 hours/day). The gross appearance of the lungs was essentially normal, but histological examination of lung sections revealed clearly abnormal macrophage reaction in five of the Cr(III) and four of the Cr(VI) exposed animals. In three rabbits from each group, there was a striking, nodular accumulation of macrophages. Most of these nodules had the appearance of intraalveolar ""naked"" granulomas, but in some areas there was a slight concomitant interstitial infiltration of lymphocytes. In general, the ultrastructure of alveolar walls and the total amount of phospholipids did not differ significantly from those in the control group. However, the macrophages of Cr(III) exposed animals had numerous intracellular lamellated inclusions, and macrophages of Cr(VI) exposed rabbits contained large lysosomes with dark patches intermingled with short membranous fragments. The morphological changes noted in the alveolar macrophages after exposure to Cr(VI) and Cr(III) were associated with only slight or no effects on lung tissue and phospholipids. The authors conclude that the chromium compounds primarily affect the macrophages. The accumulation of laminated structures in these cells after exposure to Cr(III) and the concomitant functional impairment might be due to a reduced capacity to catabolize the surfactant.","Rabbit lung after inhalation of hexa- and trivalent chromium Abs: Lung tissue from rabbits exposed to Cr(VI) (18540299) or Cr(III) (16065831) was examined by light and electron microscopy with special reference to general morphology, volume density of alveolar type 1 cells, and lung content of phospholipids. The effects of the chromium (7440473) compounds were compared with those of other metal ions, studied under similar experimental conditions. Twenty-four apparently healthy male rabbits were exposed to 0.6 +/0.4mg/m3 trivalent chromium-nitrate (13548384) or 0.9mg/m3 hexavalent disodium-chromate for 4 to 6 weeks (5 days/week and 6 hours/day). The gross appearance of the lungs was essentially normal, but histological examination of lung sections revealed clearly abnormal macrophage reaction in five of the Cr(III) and four of the Cr(VI) exposed animals. In three rabbits from each group, there was a striking, nodular accumulation of macrophages. Most of these nodules had the appearance of intraalveolar ""naked"" granulomas, but in some areas there was a slight concomitant interstitial infiltration of lymphocytes. In general, the ultrastructure of alveolar walls and the total amount of phospholipids did not differ significantly from those in the control group. However, the macrophages of Cr(III) exposed animals had numerous intracellular lamellated inclusions, and macrophages of Cr(VI) exposed rabbits contained large lysosomes with dark patches intermingled with short membranous fragments. The morphological changes noted in the alveolar macrophages after exposure to Cr(VI) and Cr(III) were associated with only slight or no effects on lung tissue and phospholipids. The authors conclude that the chromium compounds primarily affect the macrophages. The accumulation of laminated structures in these cells after exposure to Cr(III) and the concomitant functional impairment might be due to a reduced capacity to catabolize the surfactant."
63704,Glaser et al. 1986,Carcinogenicity of sodium dichromate and chromium (VI/III)oxide aerosols inhaled by male Wistar rats,"In inhalation chambers, male Wistar rats of the strain TNO-W74 were continuously exposed to submicron aerosols of sodium dichromate and to a pyrolyzed Cr(VI)/Cr(III) (3:2) oxide mixture. The sodium dichromate (Na2Cr2O7) aerosol had the chromium concentrations of 25, 50 and 100 micrograms/m3, the chromium oxide mixture (Cr5O12) had the chromium concentration of 100 micrograms/m3. After 18 months of inhalation the rats were held under conventional conditions for a further year. The experimental groups consisted of 20 rats and the control group of 40 rats. More than 90% of the rats in each group reached 2 years. At the end of the study the mortality rates amounted to 35%, 45% and 25% in the 3 sodium dichromate aerosol groups, respectively, and 50% in the chromium oxide mixture aerosol group, which was not significantly different from that of the controls (42.5%), living under the same conditions in filtered fresh air. In all sodium dichromate exposed groups significant effects were neither found clinically nor from hematology and clinical chemistry compared to the controls. In the chromium oxide mixture group, however, there was a number of significant findings. Elevated white and red blood cell counts and serum cholesterol as well as decreased serum total immunoglobulin levels at different stages of the study were observed together with few local lung effects determined histopathologically in this group. We assume that these effects are mainly due to the increased chromium lung burden of the rats. At the end of the study the lung chromium retention was about 10 times higher for the rats exposed to chromium oxide versus sodium dichromate at an aerosol Cr-concentration of 100 micrograms/m3, while the kidney chromium retention was measured to be nearly equal in both groups. Three primary lung tumors (2 adenomas and 1 adenocarcinoma) and 1 malign tumor of the pharynx were found at the highest Cr-concentration (100 micrograms/m3) of the sodium dichromate aerosol, 1 primary adenoma of the lung was in the chromium oxide mixture group exposed also to a Cr-concentration of 100 micrograms/m3. No primary lung tumors were observed in the other experimental and control groups. These results indicate a weak carcinogenicity at 100 micrograms/m3 for the rats continuously exposed to submicron Na2Cr2O7 and Cr5O12 aerosols. Thus, there may be a small carcinogenic risk from occupational relevant chromium air levels. However, results have to be confirmed with larger animal populations.","Carcinogenicity of sodium dichromate and chromium (VI/III)oxide aerosols inhaled by male Wistar rats Abs: In inhalation chambers, male Wistar rats of the strain TNO-W74 were continuously exposed to submicron aerosols of sodium dichromate and to a pyrolyzed Cr(VI)/Cr(III) (3:2) oxide mixture. The sodium dichromate (Na2Cr2O7) aerosol had the chromium concentrations of 25, 50 and 100 micrograms/m3, the chromium oxide mixture (Cr5O12) had the chromium concentration of 100 micrograms/m3. After 18 months of inhalation the rats were held under conventional conditions for a further year. The experimental groups consisted of 20 rats and the control group of 40 rats. More than 90% of the rats in each group reached 2 years. At the end of the study the mortality rates amounted to 35%, 45% and 25% in the 3 sodium dichromate aerosol groups, respectively, and 50% in the chromium oxide mixture aerosol group, which was not significantly different from that of the controls (42.5%), living under the same conditions in filtered fresh air. In all sodium dichromate exposed groups significant effects were neither found clinically nor from hematology and clinical chemistry compared to the controls. In the chromium oxide mixture group, however, there was a number of significant findings. Elevated white and red blood cell counts and serum cholesterol as well as decreased serum total immunoglobulin levels at different stages of the study were observed together with few local lung effects determined histopathologically in this group. We assume that these effects are mainly due to the increased chromium lung burden of the rats. At the end of the study the lung chromium retention was about 10 times higher for the rats exposed to chromium oxide versus sodium dichromate at an aerosol Cr-concentration of 100 micrograms/m3, while the kidney chromium retention was measured to be nearly equal in both groups. Three primary lung tumors (2 adenomas and 1 adenocarcinoma) and 1 malign tumor of the pharynx were found at the highest Cr-concentration (100 micrograms/m3) of the sodium dichromate aerosol, 1 primary adenoma of the lung was in the chromium oxide mixture group exposed also to a Cr-concentration of 100 micrograms/m3. No primary lung tumors were observed in the other experimental and control groups. These results indicate a weak carcinogenicity at 100 micrograms/m3 for the rats continuously exposed to submicron Na2Cr2O7 and Cr5O12 aerosols. Thus, there may be a small carcinogenic risk from occupational relevant chromium air levels. However, results have to be confirmed with larger animal populations."
63703,Glaser et al. 1985,Low level chromium (VI) inhalation effects on alveolar macrophages and immune functions in Wistar rats,"In inhalation chambers, 5-week-old male Wistar rats of the strain TNO-W-74 were continuously exposed to submicron aerosols of sodium dichromate in concentrations from 25 (low level) to 200 micrograms/m3 Cr (high level). Subacute exposure (28 days) to 25 and 50 micrograms/m3 Cr resulted in ""activated"" alveolar macrophages with stimulated phagocytic activities, and significantly elevated antibody responses to injected SRBC's. After subchronic (90 days) low level exposure there was a more pronounced effect on activation of the alveolar macrophages, with increased phagocytic activities. However, at high Cr (VI) exposure level (200 microgram/m3), inhibited phagocytic function of the alveolar macrophages was seen. In rats which were exposed to this chromium aerosol concentration for 42 days, the lung clearance of inert iron oxide was reduced significantly. The humoral immune system was still stimulated at subchronic low chromium aerosol concentrations of 100 micrograms/m3, but significantly depressed at 200 micrograms/m3 Cr. These results show that respiratory defence and immunologic functions were stimulated or inhibited depending on dose and time of chromium (VI) inhalation.","Low level chromium (VI) inhalation effects on alveolar macrophages and immune functions in Wistar rats Abs: In inhalation chambers, 5-week-old male Wistar rats of the strain TNO-W-74 were continuously exposed to submicron aerosols of sodium dichromate in concentrations from 25 (low level) to 200 micrograms/m3 Cr (high level). Subacute exposure (28 days) to 25 and 50 micrograms/m3 Cr resulted in ""activated"" alveolar macrophages with stimulated phagocytic activities, and significantly elevated antibody responses to injected SRBC's. After subchronic (90 days) low level exposure there was a more pronounced effect on activation of the alveolar macrophages, with increased phagocytic activities. However, at high Cr (VI) exposure level (200 microgram/m3), inhibited phagocytic function of the alveolar macrophages was seen. In rats which were exposed to this chromium aerosol concentration for 42 days, the lung clearance of inert iron oxide was reduced significantly. The humoral immune system was still stimulated at subchronic low chromium aerosol concentrations of 100 micrograms/m3, but significantly depressed at 200 micrograms/m3 Cr. These results show that respiratory defence and immunologic functions were stimulated or inhibited depending on dose and time of chromium (VI) inhalation."
63702,Ernst 1990,Testicular toxicity following short-term exposure to tri- and hexavalent chromium: an experimental study in the rat,The effect of tri- and hexavalent chromium after intraperitoneal administration for 5 consecutive days on testicular histopathology and epididymal sperm number was assessed. Treatment with hexavalent chromium induced testicular atrophy and a reduction in epididymal sperm number after 60 days. No effect was seen after treatment with trivalent chromium.,Testicular toxicity following short-term exposure to tri- and hexavalent chromium: an experimental study in the rat Abs: The effect of tri- and hexavalent chromium after intraperitoneal administration for 5 consecutive days on testicular histopathology and epididymal sperm number was assessed. Treatment with hexavalent chromium induced testicular atrophy and a reduction in epididymal sperm number after 60 days. No effect was seen after treatment with trivalent chromium.
63701,Cohen et al. 1974,Clinical manifestations of chromic acid toxicity: Nasal lesions in electroplate workers,"Clinical manifestations of chromic-acid (7738945) toxicity are described for a group of electroplate workers, with particular emphasis being placed on the etiologic factors responsible for the development of nasal lesions. Skin and nasal structures of the workers are examined and recorded in terms of standard descriptive morphology, while environmental air samples are collected from various breathing zones. Demographic data are also collected for the population. Ninety five percent of employees exposed to low atmospheric concentrations of chromic-acid are shown to have nasal pathology, while a lesser number of employees appear to develop characteristic chrome induced skin lesions. A nasal pathology spectrum is demonstrated in which the development of increasingly severe lesions appears to be related to the worker's length of exposure to chromic acid. Hexavalent chromium (7440473) is implicated in the mechanism of nasal pathology.","Clinical manifestations of chromic acid toxicity: Nasal lesions in electroplate workers Abs: Clinical manifestations of chromic-acid (7738945) toxicity are described for a group of electroplate workers, with particular emphasis being placed on the etiologic factors responsible for the development of nasal lesions. Skin and nasal structures of the workers are examined and recorded in terms of standard descriptive morphology, while environmental air samples are collected from various breathing zones. Demographic data are also collected for the population. Ninety five percent of employees exposed to low atmospheric concentrations of chromic-acid are shown to have nasal pathology, while a lesser number of employees appear to develop characteristic chrome induced skin lesions. A nasal pathology spectrum is demonstrated in which the development of increasingly severe lesions appears to be related to the worker's length of exposure to chromic acid. Hexavalent chromium (7440473) is implicated in the mechanism of nasal pathology."
62325,Wu 1988,Occupational cancer epidemiology in the People's Republic of China,"Aspects covered in this review: occupations; current methodology; important studies (vinyl chloride, cloromethyl methyl ether, bis(chloromethyl) ether, benzidine, asbestos, benzene, arsenic, chromates, coking gas, carbon, oil refineries); prospects and problems.","Occupational cancer epidemiology in the People's Republic of China Abs: Aspects covered in this review: occupations; current methodology; important studies (vinyl chloride, cloromethyl methyl ether, bis(chloromethyl) ether, benzidine, asbestos, benzene, arsenic, chromates, coking gas, carbon, oil refineries); prospects and problems."
62315,Thomann et al. 1994,Development of a pharmacokinetic model for chromium in the rat following subchronic exposure: I. The importance of incorporating long-term storage compartment,"A pharmacokinetic model of chromium depuration in the rat has been developed under subchronic exposure conditions. Rats were exposed to 100 ppm Cr(VI) in their drinking water for 6 weeks, followed by a 140-day period of depuration. Tissue concentrations of Cr at the end of the 6-week exposure period were greatest in the bone, spleen, and kidney, with lower concentrations present in the liver and blood. The overall kinetics of Cr depuration from the tissues were relatively slow, especially for the largest compartment which included bone. The results indicated that the half-life of Cr in bone exceeded 100 days. A three-compartment model was developed to fit the data. Liver, kidney, and spleen were grouped into a single compartment which was linked to a major storage compartment (i.e., bone, skin, hair, and muscle) via the blood. Using this model, the time to a 50% reduction of whole body Cr (i.e., loss of total Cr mass for the whole rat) was calculated to be about 80 days. The higher half-life for the storage compartment of 100 days is due to the relative weights of the compartments and the more rapid loss of Cr from the liver, kidney, and spleen compartment. The data suggest that Cr may be sequestered and release of Cr by the storage compartment over an extended period of time, thereby, may play an important role in maintaining elevated body burdens and tissue concentrations of Cr following long-term exposure to this toxic metal.","Development of a pharmacokinetic model for chromium in the rat following subchronic exposure: I. The importance of incorporating long-term storage compartment Abs: A pharmacokinetic model of chromium depuration in the rat has been developed under subchronic exposure conditions. Rats were exposed to 100 ppm Cr(VI) in their drinking water for 6 weeks, followed by a 140-day period of depuration. Tissue concentrations of Cr at the end of the 6-week exposure period were greatest in the bone, spleen, and kidney, with lower concentrations present in the liver and blood. The overall kinetics of Cr depuration from the tissues were relatively slow, especially for the largest compartment which included bone. The results indicated that the half-life of Cr in bone exceeded 100 days. A three-compartment model was developed to fit the data. Liver, kidney, and spleen were grouped into a single compartment which was linked to a major storage compartment (i.e., bone, skin, hair, and muscle) via the blood. Using this model, the time to a 50% reduction of whole body Cr (i.e., loss of total Cr mass for the whole rat) was calculated to be about 80 days. The higher half-life for the storage compartment of 100 days is due to the relative weights of the compartments and the more rapid loss of Cr from the liver, kidney, and spleen compartment. The data suggest that Cr may be sequestered and release of Cr by the storage compartment over an extended period of time, thereby, may play an important role in maintaining elevated body burdens and tissue concentrations of Cr following long-term exposure to this toxic metal."
61945,Hockett and  Mount 1996,Use of metal chelating agents to differentiate among sources of acute aquatic toxicity,"Metals are common toxicants found in effluents and other environmental samples. Within Toxicity Identification Evaluation methods proposed by the U.S. Environmental Protection Agency and others, addition of ethylenediaminetetraacetic acid (EDTA) is used as an indicator of metal toxicity. Previous experiments showed that addition of sodium thiosulfate, originally included to detect toxicity due to oxidants, was also effective at reducing toxicity from some common metals. In the present study, we characterized the effectiveness of both EDTA and thiosulfate in removing the toxicity of 16 different metal ions to Ceriodaphnia dubia. Ethylenediaminetetraacetic acid addition removed toxicity associated with all cationic metals tested except for Cr3+, Fe2+, Al3+, and Ag+. Thiosulfate addition was less effective than EDTA for Zn2+, Mn2+, Pb2+, and Ni2+, but reduced toxicity of both Ag+ and selenite (Se[VI]), which EDTA did not. Results of this research can be used to categorize metal toxicity in unknown samples based on the response to additions of EDTA and thiosulfate.","Use of metal chelating agents to differentiate among sources of acute aquatic toxicity Abs: Metals are common toxicants found in effluents and other environmental samples. Within Toxicity Identification Evaluation methods proposed by the U.S. Environmental Protection Agency and others, addition of ethylenediaminetetraacetic acid (EDTA) is used as an indicator of metal toxicity. Previous experiments showed that addition of sodium thiosulfate, originally included to detect toxicity due to oxidants, was also effective at reducing toxicity from some common metals. In the present study, we characterized the effectiveness of both EDTA and thiosulfate in removing the toxicity of 16 different metal ions to Ceriodaphnia dubia. Ethylenediaminetetraacetic acid addition removed toxicity associated with all cationic metals tested except for Cr3+, Fe2+, Al3+, and Ag+. Thiosulfate addition was less effective than EDTA for Zn2+, Mn2+, Pb2+, and Ni2+, but reduced toxicity of both Ag+ and selenite (Se[VI]), which EDTA did not. Results of this research can be used to categorize metal toxicity in unknown samples based on the response to additions of EDTA and thiosulfate."
60399,Fargasova 1994,Comparative toxicity of five metals on various biological subjects,Biosis copyright: biol abs. rrm research article daphnia-magna scenedesmus-quadricauda tubifex-tubifex plant soil pollution water pollution,Comparative toxicity of five metals on various biological subjects Abs: Biosis copyright: biol abs. rrm research article daphnia-magna scenedesmus-quadricauda tubifex-tubifex plant soil pollution water pollution
59497,Sferlazza and  Beckett 1991,The respiratory health of welders,"Welding as an occupation and respiratory hazards associated with welding were reviewed. Occupational surveys have indicated that 185,000 persons were employed fulltime as welders, braziers, or thermal cutters in the United States between 1981 and 1983. Approximately 800,000 were employed as fulltime welders worldwide. A much larger number of persons were employed intermittently as parttime welders. The nature of the welding process was described. Inhalation, deposition, retention, and clearance characteristics of welding fumes were considered. Acute respiratory effects resulting from welding were discussed. These included metal fume fever and chemical and hypersensitivity pneumonitis. Substances associated with acute inhalational pneumonitis in welders were discussed. The components of welding fume known to cause hypersensitivity or toxic pneumonitis include cadmium (7440439), beryllium (7440417), manganese (7439965), nitrogen oxides, ozone (10028156), phosgene (75445), and phosphine (7803512). The transient effects of welding fume exposure on lung function were discussed. Chronic respiratory effects associated with welding were reviewed and included chronic bronchitis, functional abnormalities, pneumoconiosis, and occupational asthma. Studies of lung cancer in welders were discussed. Although welding fumes have not been recognized as a major cause of bronchogenic carcinoma, the presence of recognized lung carcinogens such as hexavalent-chromium (18540299) and nickel (7440020) in welding fume and an increase in lung cancer risk noted in case/control studies have indicated that an elevated risk may exist. Methods for preventing respiratory problems in welders were discussed.","The respiratory health of welders Abs: Welding as an occupation and respiratory hazards associated with welding were reviewed. Occupational surveys have indicated that 185,000 persons were employed fulltime as welders, braziers, or thermal cutters in the United States between 1981 and 1983. Approximately 800,000 were employed as fulltime welders worldwide. A much larger number of persons were employed intermittently as parttime welders. The nature of the welding process was described. Inhalation, deposition, retention, and clearance characteristics of welding fumes were considered. Acute respiratory effects resulting from welding were discussed. These included metal fume fever and chemical and hypersensitivity pneumonitis. Substances associated with acute inhalational pneumonitis in welders were discussed. The components of welding fume known to cause hypersensitivity or toxic pneumonitis include cadmium (7440439), beryllium (7440417), manganese (7439965), nitrogen oxides, ozone (10028156), phosgene (75445), and phosphine (7803512). The transient effects of welding fume exposure on lung function were discussed. Chronic respiratory effects associated with welding were reviewed and included chronic bronchitis, functional abnormalities, pneumoconiosis, and occupational asthma. Studies of lung cancer in welders were discussed. Although welding fumes have not been recognized as a major cause of bronchogenic carcinoma, the presence of recognized lung carcinogens such as hexavalent-chromium (18540299) and nickel (7440020) in welding fume and an increase in lung cancer risk noted in case/control studies have indicated that an elevated risk may exist. Methods for preventing respiratory problems in welders were discussed."
59109,Wise et al. 2004,Comparison of two particulate hexavalent chromium compounds: Barium chromate is more genotoxic than lead chromate in human lung cells,"#Particulate hexavalent chromium [Cr(VI)] compounds are well-established human lung carcinogens. However, their carcinogenic mechanisms are poorly understood as most investigators have used soluble Cr(VI) compounds. Recent work from our laboratory has found that barium chromate (BC) is also cytotoxic and clastogenic. To understand how BC relates to existing data on other particulate Cr(VI) compounds, we compared its cytotoxicity and clastogenicity with lead chromate (LC), which has been used as a prototypical particulate Cr(VI) compound, in WTHBF-6 cells, a near-normal human lung cell line. We found that BC is a more potent cytotoxicant, inducing 67%, 12%, 3%, and 0% relative survival at concentrations of 0.1, 0.5, 1, and 5 microg/cm2, respectively, while LC induced 90%, 71%, 43%, and 15% survival at these same concentrations. We found that BC was also more clastogenic, damaging 22% and 49% of metaphase cells at 0.1 and 0.5 microg/cm2, and causing complete cell cycle arrest at 1 and 5 microg/cm2. By contrast, 0.1, 0.5, and 1.0 microg/cm2 LC damaged 10%, 27%, and 37% of metaphase cells, respectively, and complete cell cycle arrest was not observed until a concentration of 5 microg/cm2 was reached. We found that BC and LC both partially dissolved in complete medium in the presence of cells, producing similar extracellular concentrations. Both compounds were also comparable with respect to particle uptake and the amount of intracellular Cr ions. Considering previous reports showing that lead ions were inactive and that sodium chromate and LC have similar clastogenic potencies, these data suggest that BC genotoxicity may not be solely mediated by Cr ions, but also involve some clastogenic activity of barium ions.","Comparison of two particulate hexavalent chromium compounds: Barium chromate is more genotoxic than lead chromate in human lung cells Abs: #Particulate hexavalent chromium [Cr(VI)] compounds are well-established human lung carcinogens. However, their carcinogenic mechanisms are poorly understood as most investigators have used soluble Cr(VI) compounds. Recent work from our laboratory has found that barium chromate (BC) is also cytotoxic and clastogenic. To understand how BC relates to existing data on other particulate Cr(VI) compounds, we compared its cytotoxicity and clastogenicity with lead chromate (LC), which has been used as a prototypical particulate Cr(VI) compound, in WTHBF-6 cells, a near-normal human lung cell line. We found that BC is a more potent cytotoxicant, inducing 67%, 12%, 3%, and 0% relative survival at concentrations of 0.1, 0.5, 1, and 5 microg/cm2, respectively, while LC induced 90%, 71%, 43%, and 15% survival at these same concentrations. We found that BC was also more clastogenic, damaging 22% and 49% of metaphase cells at 0.1 and 0.5 microg/cm2, and causing complete cell cycle arrest at 1 and 5 microg/cm2. By contrast, 0.1, 0.5, and 1.0 microg/cm2 LC damaged 10%, 27%, and 37% of metaphase cells, respectively, and complete cell cycle arrest was not observed until a concentration of 5 microg/cm2 was reached. We found that BC and LC both partially dissolved in complete medium in the presence of cells, producing similar extracellular concentrations. Both compounds were also comparable with respect to particle uptake and the amount of intracellular Cr ions. Considering previous reports showing that lead ions were inactive and that sodium chromate and LC have similar clastogenic potencies, these data suggest that BC genotoxicity may not be solely mediated by Cr ions, but also involve some clastogenic activity of barium ions."
58502,Bates and  Scheel 1974,Processing emissions and occupational health in the ferrous foundry industry,"HEEP COPYRIGHT: BIOL ABS. Ferrous foundry effluent produced during melting, pouring and casting shakeout was studied. Some decomposition products of 4 types of organic foundry mold resins were identified using gas chromatographic and IR methods. The survey may provide some insight into the types of materials that are hazardous to human health.","Processing emissions and occupational health in the ferrous foundry industry Abs: HEEP COPYRIGHT: BIOL ABS. Ferrous foundry effluent produced during melting, pouring and casting shakeout was studied. Some decomposition products of 4 types of organic foundry mold resins were identified using gas chromatographic and IR methods. The survey may provide some insight into the types of materials that are hazardous to human health."
57899,Patierno et al. 1988,Transformation of C3H/10T1/2 mouse embryo cells to focus formation and anchorage independence by insoluble lead chromate but not soluble calcium chromate: relationship to mutagenesis and internalization of lead chromate particles,"#The genotoxicity of soluble and insoluble hexavalent chromium compounds was studied in mammalian cell assays which detect base substitution, deletion, addition, and frameshift mutations [6-thioguanine resistance in Chinese hamster ovary cells], primarily base substitution mutations [ouabain resistance in Chinese hamster ovary and C3H/10T Cl 8 mouse embryo fibroblasts (10T)] and morphological transformation [focus formation] in 10T cells. Soluble hexavalent CaCrO4, administered in either acute (5-h) or subacute (24-h) dosing regimens, induced dose-dependent cytotoxicity and mutation to 6-thioguanine resistance in Chinese hamster ovary cells but no mutation to ouabain resistance or focus formation in transformation assays, although the acute treatment induced a high frequency of conversion of 10T cells to adipocytes. Cell lines established from cloned adipocytic cells were not morphologically transformed and did not grow in soft agarose. PbCrO4 did not induce mutation to either 6-thioguanine or ouabain resistance but did induce a reproducible dose-dependent, low frequency of focus formation in 10T cells. Cell lines established from PbCrO4-induced foci stably formed foci when coseeded with 10T cells, had 3û5-fold increased saturation densities relative to nontransformed 10T cells, and formed colonies in soft agarose, indicating their likelihood to be neoplastic. Long term exposure of 10T cells to either CaCrO4 or PbCl2, even at 85% cytotoxic concentrations, or pretreatment of cells with either CaCrO4 or PbCl2 followed by treatment with the alternate compound, did not induce morphological transformation. Treatment of cells with insoluble hexavalent PbCrO4 resulted in progressive and extensive vacuolization of cells in contact with the particles. Progressive cytoplasmic engulfment of PbCrO4 particles was observed using scanning electron microscopy, although PbCrO4 particles were not observed inside vacuoles. These results indicated that the soluble clastogens K2Cr2O7 and CaCrO4 were probably mutagenic by a non-base substitution mechanism but could not transform 10T cells. In contrast, PbCrO4 was not detectably mutagenic but induced transformation, which could not be explained solely by acute or chronic exposure to dissolution products of either lead or chromate alone. Since PbCrO4 particles were found to be intracytoplasmic in extensively vacuolated cells, we suggest that the unique physicochemical properties of PbCrO4 particles, leading to their internalization and the resultant associated cellular stress response, may be related to the transformation induced by this compound.","Transformation of C3H/10T1/2 mouse embryo cells to focus formation and anchorage independence by insoluble lead chromate but not soluble calcium chromate: relationship to mutagenesis and internalization of lead chromate particles Abs: #The genotoxicity of soluble and insoluble hexavalent chromium compounds was studied in mammalian cell assays which detect base substitution, deletion, addition, and frameshift mutations [6-thioguanine resistance in Chinese hamster ovary cells], primarily base substitution mutations [ouabain resistance in Chinese hamster ovary and C3H/10T Cl 8 mouse embryo fibroblasts (10T)] and morphological transformation [focus formation] in 10T cells. Soluble hexavalent CaCrO4, administered in either acute (5-h) or subacute (24-h) dosing regimens, induced dose-dependent cytotoxicity and mutation to 6-thioguanine resistance in Chinese hamster ovary cells but no mutation to ouabain resistance or focus formation in transformation assays, although the acute treatment induced a high frequency of conversion of 10T cells to adipocytes. Cell lines established from cloned adipocytic cells were not morphologically transformed and did not grow in soft agarose. PbCrO4 did not induce mutation to either 6-thioguanine or ouabain resistance but did induce a reproducible dose-dependent, low frequency of focus formation in 10T cells. Cell lines established from PbCrO4-induced foci stably formed foci when coseeded with 10T cells, had 3û5-fold increased saturation densities relative to nontransformed 10T cells, and formed colonies in soft agarose, indicating their likelihood to be neoplastic. Long term exposure of 10T cells to either CaCrO4 or PbCl2, even at 85% cytotoxic concentrations, or pretreatment of cells with either CaCrO4 or PbCl2 followed by treatment with the alternate compound, did not induce morphological transformation. Treatment of cells with insoluble hexavalent PbCrO4 resulted in progressive and extensive vacuolization of cells in contact with the particles. Progressive cytoplasmic engulfment of PbCrO4 particles was observed using scanning electron microscopy, although PbCrO4 particles were not observed inside vacuoles. These results indicated that the soluble clastogens K2Cr2O7 and CaCrO4 were probably mutagenic by a non-base substitution mechanism but could not transform 10T cells. In contrast, PbCrO4 was not detectably mutagenic but induced transformation, which could not be explained solely by acute or chronic exposure to dissolution products of either lead or chromate alone. Since PbCrO4 particles were found to be intracytoplasmic in extensively vacuolated cells, we suggest that the unique physicochemical properties of PbCrO4 particles, leading to their internalization and the resultant associated cellular stress response, may be related to the transformation induced by this compound."
57810,Nordberg 1988,Current concepts in the assessment of effects of metals in chronic low-level exposures: considerations of experimental and epidemiological evidence,"Human exposure to metals and their compounds may give rise to a number of adverse effects. Of particular interest are such effects that can be elicitated by chronic low-level exposure, since such exposures may occur in human populations both in the general environment and occupationally. The adverse effect that occurs at the lowest exposure has been termed the &quot;critical effect&quot; since it is critical in relation to preventive action aiming at limiting exposures to a safe level. When reviewing the present evidence on the toxicology of metals it becomes evident that &quot;critical effects&quot; may be related to various organ systems, disease categories and biochemical mechanisms of damage. A category of effects, which is of particular interest in relation to critical effects, is hypersensitivity (e.g. with dermal or respiratory manifestations). However conceptual recognition of this category of effects is as yet incomplete. Other important considerations are whether effects display threshold- or non-threshold type dose-response relationships, the latter category obviously being more likely to display a low incidence response at low dose exposure. In this context mutagenic, carcinogenic, developmental and reproductive toxicity of metals are of particular interest. Information on these types of effects compiled during previous meetings of the scientific committee on the toxicilogy of metals and recently updated, indicates that some compounds of arsenic, beryllium, cadmium, chromium and nickel may be regarded as carcinogenic for humans. Available evidence in experimental systems as well as in humans concerning effects of metallic compounds on male and female reproductive systems, congenital teratogenicity and perinatal toxicity as well as effects on the developing central nervous system indicates that such effects should be considered further in relation to critical effects for arsenic, cadmium, lead, mercury and their compounds.","Current concepts in the assessment of effects of metals in chronic low-level exposures: considerations of experimental and epidemiological evidence Abs: Human exposure to metals and their compounds may give rise to a number of adverse effects. Of particular interest are such effects that can be elicitated by chronic low-level exposure, since such exposures may occur in human populations both in the general environment and occupationally. The adverse effect that occurs at the lowest exposure has been termed the &quot;critical effect&quot; since it is critical in relation to preventive action aiming at limiting exposures to a safe level. When reviewing the present evidence on the toxicology of metals it becomes evident that &quot;critical effects&quot; may be related to various organ systems, disease categories and biochemical mechanisms of damage. A category of effects, which is of particular interest in relation to critical effects, is hypersensitivity (e.g. with dermal or respiratory manifestations). However conceptual recognition of this category of effects is as yet incomplete. Other important considerations are whether effects display threshold- or non-threshold type dose-response relationships, the latter category obviously being more likely to display a low incidence response at low dose exposure. In this context mutagenic, carcinogenic, developmental and reproductive toxicity of metals are of particular interest. Information on these types of effects compiled during previous meetings of the scientific committee on the toxicilogy of metals and recently updated, indicates that some compounds of arsenic, beryllium, cadmium, chromium and nickel may be regarded as carcinogenic for humans. Available evidence in experimental systems as well as in humans concerning effects of metallic compounds on male and female reproductive systems, congenital teratogenicity and perinatal toxicity as well as effects on the developing central nervous system indicates that such effects should be considered further in relation to critical effects for arsenic, cadmium, lead, mercury and their compounds."
57391,Montaldi et al. 1987,"Chromosomal effects of heavy metals (Cd, Cr, Hg, Ni and Pb) on cultured mammalian cells in the presence of nitrilotriacetic acid (NTA)","Genotoxic metals are diffused in the environment, and are often sequestered as insoluble precipitates in water sediments and sludges. Their solubilization by chelating agents is well documented and is recognized as the major hazard deriving from the introduction of NTA. Soluble metal compounds (CdCl2, K2Cr2O7, HgCl2, and NiCl2) significantly increase the SCE frequency in cultured hamster cells (CHO line) with a clear dose?effect relationship, and the addition of equimolar concentrations of NTA apparently does not enhance SCE induction by these metals. On the other hand, the SCE frequencies are significantly increased in a dose?dependent manner by insoluble metal compounds (CdCO3, PbCrO4, HgCl, NiCO3 and PbSO4), and a significant increase of this effect is seen in the presence of equimolar concentrations of NTA. An interaction of NTA with the insoluble metal compounds, particularly CdCO3, HgCl and PbSO4, may also be inferred from statistically significant increases in the frequencies of micronuclei and chromosomal aberrations (both gaps, mono? and isochromatid breaks and fragments) in human lymphocytes treated in vitro with metals in the presence of NTA, compared to the frequencies induced by metals alone.","Chromosomal effects of heavy metals (Cd, Cr, Hg, Ni and Pb) on cultured mammalian cells in the presence of nitrilotriacetic acid (NTA) Abs: Genotoxic metals are diffused in the environment, and are often sequestered as insoluble precipitates in water sediments and sludges. Their solubilization by chelating agents is well documented and is recognized as the major hazard deriving from the introduction of NTA. Soluble metal compounds (CdCl2, K2Cr2O7, HgCl2, and NiCl2) significantly increase the SCE frequency in cultured hamster cells (CHO line) with a clear dose?effect relationship, and the addition of equimolar concentrations of NTA apparently does not enhance SCE induction by these metals. On the other hand, the SCE frequencies are significantly increased in a dose?dependent manner by insoluble metal compounds (CdCO3, PbCrO4, HgCl, NiCO3 and PbSO4), and a significant increase of this effect is seen in the presence of equimolar concentrations of NTA. An interaction of NTA with the insoluble metal compounds, particularly CdCO3, HgCl and PbSO4, may also be inferred from statistically significant increases in the frequencies of micronuclei and chromosomal aberrations (both gaps, mono? and isochromatid breaks and fragments) in human lymphocytes treated in vitro with metals in the presence of NTA, compared to the frequencies induced by metals alone."
57328,Sharma and  Talukder 1987,Effects of metals on chromosomes of higher organisms,"An analysis of the available data on the clastogenic effects of metals and their compounds on higher organisms indicates some general trends. Following chronic exposure to subtoxic doses, a decrease in mitotic frequency and an increase in the number of chromosomal abnormalities are observed. These effects are usually directly proportional to the dose applied and the duration of treatment within the threshold limits. Recovery after acute treatment is inversely related to the dosage. The ultimate expression of the effects depends on certain factors, including the mode and vehicle of administration; the form administered; the test system used; the rate of detoxification, distribution, and retention in the different tissues; and interaction with foreign and endogenous substances as well as the mode of action with the biological macromolecules. In mammals, the clastogenic activity of the metals within each vertical group of the periodic table is directly proportional to the increase in atomic weight, electropositivity, and solubility of the metallic cations in water and lipids, except for Li and Ba. This pattern of inherent cytotoxicity increases with successive periods in the horizontal level. It is enhanced by the formation of covalent and coordinate covalent complexes by heavy metals with the biological macromolecules. In plants, the solubility of the metals in water is of much greater importance. The degree of dissociation of metallic salts and the rate of absorption affect significantly the frequency of chromosomal aberrations. In assessing the effects of environmental metal pollution, the presence of other metals and toxic chemicals and the level of nutrition should be taken into account, since in nature, metals occur in combination and these factors modify the cytotoxic effects to a significant extent.","Effects of metals on chromosomes of higher organisms Abs: An analysis of the available data on the clastogenic effects of metals and their compounds on higher organisms indicates some general trends. Following chronic exposure to subtoxic doses, a decrease in mitotic frequency and an increase in the number of chromosomal abnormalities are observed. These effects are usually directly proportional to the dose applied and the duration of treatment within the threshold limits. Recovery after acute treatment is inversely related to the dosage. The ultimate expression of the effects depends on certain factors, including the mode and vehicle of administration; the form administered; the test system used; the rate of detoxification, distribution, and retention in the different tissues; and interaction with foreign and endogenous substances as well as the mode of action with the biological macromolecules. In mammals, the clastogenic activity of the metals within each vertical group of the periodic table is directly proportional to the increase in atomic weight, electropositivity, and solubility of the metallic cations in water and lipids, except for Li and Ba. This pattern of inherent cytotoxicity increases with successive periods in the horizontal level. It is enhanced by the formation of covalent and coordinate covalent complexes by heavy metals with the biological macromolecules. In plants, the solubility of the metals in water is of much greater importance. The degree of dissociation of metallic salts and the rate of absorption affect significantly the frequency of chromosomal aberrations. In assessing the effects of environmental metal pollution, the presence of other metals and toxic chemicals and the level of nutrition should be taken into account, since in nature, metals occur in combination and these factors modify the cytotoxic effects to a significant extent."
56724,Andersen 1983,Effects of coal combustion products and metal compounds on sister chromatid exchange (SCE) in a macrophagelike cell line,"Investigations of genotoxic effects of particles have almost exclusively been performed by organic extraction, while direct investigations in cells capable of engulfing particles have only been performed in few cases. Thus, in most studies, the eventual effects of particle-associated metal compounds have remained undiscovered. The present study attempted direct measurement of genotoxic effects of particulate coal combustion products by using the P388D1 macrophage cell line. The capability of these cells for phagocytosis was demonstrated with insoluble particles. The sister chromatid exchange (SCE) test was used for measuring genotoxic effects of test compounds. Dimethylnitrosamine and benzo(a)pyrene did not increase SCE, indicating that the P388D1 cell line has lost the capacity for metabolism of latent organic carcinogens, reducing the value of these cells for evaluating genotoxic effects of complex particles. Indirect evidence has been obtained that the cell line may be infected with a virus. Thus, interactions between virus and test compound may lead to erroneous results. This should be kept in mind during evaluation of the results.The effects of metals with reported carcinogenic or mutagenic effects on SCE were compared in P388D1 cells and human lymphocytes: NaAsO2, CdCl2, K2Cr2O7, CoCl2, CH3HgCl and MnSO4 increased SCE in both cell systems. Pb(CH3COO)2, BeSO4 and NiSO4 had a weak effect on SCE in P388D1. Pb(CH3COO)2 and NiSO4, but not BeSO4, increased SCE in human lymphocytes. Cr(CH3COO)3 increased SCE in human lymphocytes at high concentration, but was a strong inducer of increased SCE in P388D1 cells, which take up Cr(III) by phagocytosis. This suggests that the Cr(III) ion is an ultimate carcinogenic form of chromium. Generally P388D1 cells and human lymphocytes respond to in vitro exposure to metals in agreement with reported mutagenic/carcinogenic effects of the metals.Of four precipitated coal fly ash samples tested, only one sample (from an electrostatic precipitator downstream of a cyclone at an electricity generating plant burning pulverized coal) had a clear increasing effect on SCE in P388D1. Extraction of this sample with medium with 10% serum yielded an extract capable of increasing SCE. The extracted particles still increased SCE, but less than unextracted particles.Emission samples taken with impactor sampler after a dilution probe using controlled cooling of the flue gas were obtained from an oil-fired (one sample) and a coal-fired (one sample < 3 ?m and one sample < 3 ?m) steam boiler. The only sample increasing SCE was the sample < 3 ?m from the coal-fired boiler. Extract from this sample also increased SCE.The results demonstrated that the use of phagocytizing cells for assessment of genotoxic effects of particles offers a useful system, since the particles can be investigated directly. Furthermore, particles, extracted particles and extract can be investigated in the same system.","Effects of coal combustion products and metal compounds on sister chromatid exchange (SCE) in a macrophagelike cell line Abs: Investigations of genotoxic effects of particles have almost exclusively been performed by organic extraction, while direct investigations in cells capable of engulfing particles have only been performed in few cases. Thus, in most studies, the eventual effects of particle-associated metal compounds have remained undiscovered. The present study attempted direct measurement of genotoxic effects of particulate coal combustion products by using the P388D1 macrophage cell line. The capability of these cells for phagocytosis was demonstrated with insoluble particles. The sister chromatid exchange (SCE) test was used for measuring genotoxic effects of test compounds. Dimethylnitrosamine and benzo(a)pyrene did not increase SCE, indicating that the P388D1 cell line has lost the capacity for metabolism of latent organic carcinogens, reducing the value of these cells for evaluating genotoxic effects of complex particles. Indirect evidence has been obtained that the cell line may be infected with a virus. Thus, interactions between virus and test compound may lead to erroneous results. This should be kept in mind during evaluation of the results.The effects of metals with reported carcinogenic or mutagenic effects on SCE were compared in P388D1 cells and human lymphocytes: NaAsO2, CdCl2, K2Cr2O7, CoCl2, CH3HgCl and MnSO4 increased SCE in both cell systems. Pb(CH3COO)2, BeSO4 and NiSO4 had a weak effect on SCE in P388D1. Pb(CH3COO)2 and NiSO4, but not BeSO4, increased SCE in human lymphocytes. Cr(CH3COO)3 increased SCE in human lymphocytes at high concentration, but was a strong inducer of increased SCE in P388D1 cells, which take up Cr(III) by phagocytosis. This suggests that the Cr(III) ion is an ultimate carcinogenic form of chromium. Generally P388D1 cells and human lymphocytes respond to in vitro exposure to metals in agreement with reported mutagenic/carcinogenic effects of the metals.Of four precipitated coal fly ash samples tested, only one sample (from an electrostatic precipitator downstream of a cyclone at an electricity generating plant burning pulverized coal) had a clear increasing effect on SCE in P388D1. Extraction of this sample with medium with 10% serum yielded an extract capable of increasing SCE. The extracted particles still increased SCE, but less than unextracted particles.Emission samples taken with impactor sampler after a dilution probe using controlled cooling of the flue gas were obtained from an oil-fired (one sample) and a coal-fired (one sample < 3 ?m and one sample < 3 ?m) steam boiler. The only sample increasing SCE was the sample < 3 ?m from the coal-fired boiler. Extract from this sample also increased SCE.The results demonstrated that the use of phagocytizing cells for assessment of genotoxic effects of particles offers a useful system, since the particles can be investigated directly. Furthermore, particles, extracted particles and extract can be investigated in the same system."
56406,Tucker et al. 1993,Sister-chromatid exchange: second report of the Gene-Tox program,"This paper reviews the ability of a number of chemicals to induce sister-chromatid exchanges (SCEs). The SCE data for animal cells in vivo and in vitro, and human cells in vitro are presented in 6 tables according to their relative effectiveness. A seventh table summarizes what is known about the effects of specific chemicals on SCEs for humans exposed in vivo. The data support the concept that SCEs provide a useful indication of exposure, although the mechanism and biological significance of SCE formation still remain to be elucidated.","Sister-chromatid exchange: second report of the Gene-Tox program Abs: This paper reviews the ability of a number of chemicals to induce sister-chromatid exchanges (SCEs). The SCE data for animal cells in vivo and in vitro, and human cells in vitro are presented in 6 tables according to their relative effectiveness. A seventh table summarizes what is known about the effects of specific chemicals on SCEs for humans exposed in vivo. The data support the concept that SCEs provide a useful indication of exposure, although the mechanism and biological significance of SCE formation still remain to be elucidated."
56277,Davies 1984,Lung cancer mortality among workers making lead chromate and zinc chromate pigments at three English factories,"Lung cancer mortality among 1152 men working at three English chromate pigment factories was studied from the 1930s or 1940s until 1981. Workers at factory C were exposed only to lead chromate and experienced normal mortality (Obs/Exp deaths 7/6.45). Workers at factories A and B were exposed to both lead and zinc chromate; mortality was normal among those who had only low exposure (O/E 7/6.95). For workers with high or medium exposure lung cancer mortality was significantly raised among men remaining at least a year after entering service at factory A during 1932-54 (O/E 21/9.45) and at factory B during 1948-67 (O/E 11/2.50). At factory A, 1933-46 entrants staying only 3-11 months were not affected (O/E 6/5.04) and 1955-63 entrants also appeared unaffected (O/E 2/2.00); working conditions there improved in 1955. The hazard at factories A and B affected workers who left after one year as well as those with longer service, and latent intervals were unusually short. The results indicate that moderate or heavy exposure to zinc chromate may give rise to a severe risk of developing lung cancer, but that exposure which is relatively mild or lasts less than a year may not constitute an effective risk. The results provide no indication that lead chromate induces lung cancer in man, even under conditions conducive to lead poisoning.","Lung cancer mortality among workers making lead chromate and zinc chromate pigments at three English factories Abs: Lung cancer mortality among 1152 men working at three English chromate pigment factories was studied from the 1930s or 1940s until 1981. Workers at factory C were exposed only to lead chromate and experienced normal mortality (Obs/Exp deaths 7/6.45). Workers at factories A and B were exposed to both lead and zinc chromate; mortality was normal among those who had only low exposure (O/E 7/6.95). For workers with high or medium exposure lung cancer mortality was significantly raised among men remaining at least a year after entering service at factory A during 1932-54 (O/E 21/9.45) and at factory B during 1948-67 (O/E 11/2.50). At factory A, 1933-46 entrants staying only 3-11 months were not affected (O/E 6/5.04) and 1955-63 entrants also appeared unaffected (O/E 2/2.00); working conditions there improved in 1955. The hazard at factories A and B affected workers who left after one year as well as those with longer service, and latent intervals were unusually short. The results indicate that moderate or heavy exposure to zinc chromate may give rise to a severe risk of developing lung cancer, but that exposure which is relatively mild or lasts less than a year may not constitute an effective risk. The results provide no indication that lead chromate induces lung cancer in man, even under conditions conducive to lead poisoning."
56109,Stohs et al. 2001,Oxidative mechanisms in the toxicity of chromium and cadmium ions,"Chromium and cadmium are widely used industrial chemicals. The toxicities associated with both metal ions are well known. However, less information is available concerning the mechanisms of toxicity. The results of in vitro and in vivo studies demonstrate that both cations induce an oxidative stress that results in oxidative deterioration of biological macromolecules. However, different mechanisms are involved in the production of oxidative stress by chromium and cadmium. Chromium undergoes redox cycling, while cadmium depletes glutathione and protein-bound sulfhydryl groups, resulting in enhanced production of reactive oxygen species such as superoxide ion, hydroxyl radicals, and hydrogen peroxide. These reactive oxygen species result in increased lipid peroxidation, enhanced excretion of urinary lipid metabolites, modulation of intracellular oxidized states, DNA damage, membrane damage, altered gene expression, and apoptosis. Enhanced production of nuclear factor-kappaB and activation of protein kinase C occur. Furthermore, the p53 tumor suppressor gene is involved in the cascade of events associated with the toxicities of these cations. In summary, the results clearly indicate that although different mechanisms lead to the production of reactive oxygen species by chromium and cadmium, similar subsequent mechanisms and types of oxidative tissue damage are involved in the overall toxicities.","Oxidative mechanisms in the toxicity of chromium and cadmium ions Abs: Chromium and cadmium are widely used industrial chemicals. The toxicities associated with both metal ions are well known. However, less information is available concerning the mechanisms of toxicity. The results of in vitro and in vivo studies demonstrate that both cations induce an oxidative stress that results in oxidative deterioration of biological macromolecules. However, different mechanisms are involved in the production of oxidative stress by chromium and cadmium. Chromium undergoes redox cycling, while cadmium depletes glutathione and protein-bound sulfhydryl groups, resulting in enhanced production of reactive oxygen species such as superoxide ion, hydroxyl radicals, and hydrogen peroxide. These reactive oxygen species result in increased lipid peroxidation, enhanced excretion of urinary lipid metabolites, modulation of intracellular oxidized states, DNA damage, membrane damage, altered gene expression, and apoptosis. Enhanced production of nuclear factor-kappaB and activation of protein kinase C occur. Furthermore, the p53 tumor suppressor gene is involved in the cascade of events associated with the toxicities of these cations. In summary, the results clearly indicate that although different mechanisms lead to the production of reactive oxygen species by chromium and cadmium, similar subsequent mechanisms and types of oxidative tissue damage are involved in the overall toxicities."
55567,Bragt and  van Dura 1983,Toxicokinetics of hexavalent chromium in the rat after intratracheal administration of chromates of different solubilities,"The kinetics of chromium in the rat after a single intratracheal dose of sodium, zinc or lead 51Cr-chromate have been investigated. Sodium chromate and the less soluble zinc chromate were absorbed into the blood and this resulted in increased excretion of chromium into the urine. The insoluble lead chromate was poorly absorbed from the lungs. The more insoluble a chromate was in water, the higher its elimination via the feces. With all three chromates, absorbed chromium was retained in the spleen and the bone marrow. After the administration of sodium chromate, chromium was also retained in the liver and kidneys. On the basis of the minor resorption of lead chromate, it is concluded that chromium levels in blood and urine are not indicative of exposure to insoluble chromates via the inhalatory route.","Toxicokinetics of hexavalent chromium in the rat after intratracheal administration of chromates of different solubilities Abs: The kinetics of chromium in the rat after a single intratracheal dose of sodium, zinc or lead 51Cr-chromate have been investigated. Sodium chromate and the less soluble zinc chromate were absorbed into the blood and this resulted in increased excretion of chromium into the urine. The insoluble lead chromate was poorly absorbed from the lungs. The more insoluble a chromate was in water, the higher its elimination via the feces. With all three chromates, absorbed chromium was retained in the spleen and the bone marrow. After the administration of sodium chromate, chromium was also retained in the liver and kidneys. On the basis of the minor resorption of lead chromate, it is concluded that chromium levels in blood and urine are not indicative of exposure to insoluble chromates via the inhalatory route."
55559,Davidson et al. 2004,Exposure to chromium (VI) in the drinking water increases susceptibility to UV-induced skin tumors in hairless mice,"Hexavalent chromium (Cr (VI)) is a well known-human carcinogen with exposures occurring in both occupational and environmental settings. Although lung carcinogenicity has been well documented for occupational exposure via inhalation, the carcinogenic hazard of drinking water exposure to Cr (VI) has yet to be established. We used a hairless mouse model to study the effects of K2CrO4 in the drinking water on ultraviolet radiation (UVR)-induced skin tumors. Hairless mice were unexposed or exposed to UVR alone (1.2 kJ/m2), K2CrO4 alone at 2.5 and 5.0 ppm, or the combination of UVR and K2CrO4 at 0.5, 2.5, and 5.0 ppm. Mice were observed on a weekly basis for the appearance of skin tumors larger than 2 mm. All the mice were euthanized on day 182. The skin tumors were excised and subsequently analyzed microscopically for malignancy by histopathology. There was a total absence of observable skin tumors in untreated mice and in mice exposed to chromate alone. However, there was a dose-dependent increase in the number of skin tumors greater than 2 mm in mice exposed to K2CrO4 and UV compared with mice exposed to UV alone. The increase in tumors larger than 2 mm was statistically significant (P < 0.05) for UV and K2CrO4 at the two highest K2CrO4 doses (2.5 and 5.0 ppm), and there was a statistically significant increase in the numbers of malignant tumors per mouse in the UVR plus K2CrO4 (5 ppm) group compared with UV alone. The data presented here indicate that K2CrO4 increases the number of UV-induced skin tumors in a dose-dependent manner, and these results support the concern that regulatory agencies have relative to the carcinogenic health hazards of widespread human exposure to Cr (VI) in drinking water.","Exposure to chromium (VI) in the drinking water increases susceptibility to UV-induced skin tumors in hairless mice Abs: Hexavalent chromium (Cr (VI)) is a well known-human carcinogen with exposures occurring in both occupational and environmental settings. Although lung carcinogenicity has been well documented for occupational exposure via inhalation, the carcinogenic hazard of drinking water exposure to Cr (VI) has yet to be established. We used a hairless mouse model to study the effects of K2CrO4 in the drinking water on ultraviolet radiation (UVR)-induced skin tumors. Hairless mice were unexposed or exposed to UVR alone (1.2 kJ/m2), K2CrO4 alone at 2.5 and 5.0 ppm, or the combination of UVR and K2CrO4 at 0.5, 2.5, and 5.0 ppm. Mice were observed on a weekly basis for the appearance of skin tumors larger than 2 mm. All the mice were euthanized on day 182. The skin tumors were excised and subsequently analyzed microscopically for malignancy by histopathology. There was a total absence of observable skin tumors in untreated mice and in mice exposed to chromate alone. However, there was a dose-dependent increase in the number of skin tumors greater than 2 mm in mice exposed to K2CrO4 and UV compared with mice exposed to UV alone. The increase in tumors larger than 2 mm was statistically significant (P < 0.05) for UV and K2CrO4 at the two highest K2CrO4 doses (2.5 and 5.0 ppm), and there was a statistically significant increase in the numbers of malignant tumors per mouse in the UVR plus K2CrO4 (5 ppm) group compared with UV alone. The data presented here indicate that K2CrO4 increases the number of UV-induced skin tumors in a dose-dependent manner, and these results support the concern that regulatory agencies have relative to the carcinogenic health hazards of widespread human exposure to Cr (VI) in drinking water."
55313,Nishioka 1975,Mutagenic activities of metal compounds in bacteria,"HEEP COPYRIGHT: BIOL ABS. Several metal compounds which can be environmental health hazards, were tested for mutagenicity in Bacillus subtilis. Some were also tested for their capacities to induce reversions in Escherichia coli strains possessing different DNA repair pathways.","Mutagenic activities of metal compounds in bacteria Abs: HEEP COPYRIGHT: BIOL ABS. Several metal compounds which can be environmental health hazards, were tested for mutagenicity in Bacillus subtilis. Some were also tested for their capacities to induce reversions in Escherichia coli strains possessing different DNA repair pathways."
55301,Heck and  Costa 1982,In vitro assessment of the toxicity of metal compounds: II mutagenesis,"A review of in vitro mutagenesis assessment of metal compounds in mammalian and nonmammalian test systems has been compiled. Prokaryotic assays are ineffective or inconsistent in their detection of most metals as mutagens, with the notable exception of hexavalent chromium. Mammalian assay systems appear to be similarly inappropriate for the screening of metal compounds based upon the limited number of studies that have employed those compounds having known carcinogenic activity. Although of limited value as screening tests for the detection of potentially carcinogenic metal compounds, the well-characterized in vitro mutagenesis systems may prove to be of significant value as a means to elucidate mechanisms of metal genotoxicity.","In vitro assessment of the toxicity of metal compounds: II mutagenesis Abs: A review of in vitro mutagenesis assessment of metal compounds in mammalian and nonmammalian test systems has been compiled. Prokaryotic assays are ineffective or inconsistent in their detection of most metals as mutagens, with the notable exception of hexavalent chromium. Mammalian assay systems appear to be similarly inappropriate for the screening of metal compounds based upon the limited number of studies that have employed those compounds having known carcinogenic activity. Although of limited value as screening tests for the detection of potentially carcinogenic metal compounds, the well-characterized in vitro mutagenesis systems may prove to be of significant value as a means to elucidate mechanisms of metal genotoxicity."
54946,Furst et al. 1976,Tumorigenic activity of lead chromate,"Lead chromate was investigated for its carcinogenic potential in both rats and mice. Results show that this compound is a very potent carcinogen in rats when administered i.m. Sixty-four % of the animals treated developed malignant tumors at the injection site. Three renal carcinomas were also found after i.m. treatment with lead chromate. Since lead powder is a comparatively weak carcinogen in rats, whether given p.o. or i.m., it is suggested that the combination of lead and chromium (also a weak carcinogen) accounts for the high carcinogenic activity of lead chromate in rats. Swiss albino female mice could not tolerate the same high dose level as did the rats; at the lower dose administered to the mice, no tumors were detected.","Tumorigenic activity of lead chromate Abs: Lead chromate was investigated for its carcinogenic potential in both rats and mice. Results show that this compound is a very potent carcinogen in rats when administered i.m. Sixty-four % of the animals treated developed malignant tumors at the injection site. Three renal carcinomas were also found after i.m. treatment with lead chromate. Since lead powder is a comparatively weak carcinogen in rats, whether given p.o. or i.m., it is suggested that the combination of lead and chromium (also a weak carcinogen) accounts for the high carcinogenic activity of lead chromate in rats. Swiss albino female mice could not tolerate the same high dose level as did the rats; at the lower dose administered to the mice, no tumors were detected."
54922,Stayner et al. 2003,Attenuation of exposure-response curves in occupational cohort studies at high exposure levels,"Numerous occupational cohort mortality studies have observed exposure-response curves to have an increasing slope at low exposure levels that attenuates or even turns negative at high exposure levels. Examples discussed in this paper include dioxin, silica, 1 ,3-butadiene, cadmium, beryllium, radon daughters, diesel fumes, nickel, arsenic, and hexavalent chromium. Possible explanations for this phenomenon include (i) bias introduced by the healthy worker survivor effect, (ii) a depletion of the number of susceptible people in the population at high exposure levels, (iii) a natural limit on the relative risk for diseases with a high background rate, (iv) mismeasurement or misclassification of exposures, (v) the influence of other risk factors that vary by the level of the main exposure, and (vi) the saturation of key enzyme systems or other processes involved in the development of disease.","Attenuation of exposure-response curves in occupational cohort studies at high exposure levels Abs: Numerous occupational cohort mortality studies have observed exposure-response curves to have an increasing slope at low exposure levels that attenuates or even turns negative at high exposure levels. Examples discussed in this paper include dioxin, silica, 1 ,3-butadiene, cadmium, beryllium, radon daughters, diesel fumes, nickel, arsenic, and hexavalent chromium. Possible explanations for this phenomenon include (i) bias introduced by the healthy worker survivor effect, (ii) a depletion of the number of susceptible people in the population at high exposure levels, (iii) a natural limit on the relative risk for diseases with a high background rate, (iv) mismeasurement or misclassification of exposures, (v) the influence of other risk factors that vary by the level of the main exposure, and (vi) the saturation of key enzyme systems or other processes involved in the development of disease."
54182,Pascal and  Tessier 2004,Cytotoxicity of chromium and manganese to lung epithelial cells in vitro,"Chromium, nickel and manganese are the predominant metals in welding fumes and are associated through epidemiological studies with an increased risk for developing occupational asthma due to welding activities. Here, we show that chromium(VI) and manganese, but not nickel, are cytotoxic to normal human lung epithelial cells in vitro (SAEC and BEAS-2B), at concentration ranges of 0.2-200 ÁM. The toxic effect was associated with increased levels of intracellular phosphoprotein and subsequent release of inflammatory cytokines IL-6 and IL-8, while no release of TNF- was observed. Changes in intracellular phosphoprotein levels occurred at concentrations below the cytotoxic effect. IL-6 and IL-8 production increased up to 4.4-fold relative to controls. IL-6 and IL-8 are released from lung epithelium to recruit cells of the immune system to sites of tissue damage. Therefore, the observed effects of chromium(VI) and manganese in lung epithelial cells demonstrate a mechanism through which the toxicity of these metals to epithelial cells can result in recruitment of cells of the immune system.","Cytotoxicity of chromium and manganese to lung epithelial cells in vitro Abs: Chromium, nickel and manganese are the predominant metals in welding fumes and are associated through epidemiological studies with an increased risk for developing occupational asthma due to welding activities. Here, we show that chromium(VI) and manganese, but not nickel, are cytotoxic to normal human lung epithelial cells in vitro (SAEC and BEAS-2B), at concentration ranges of 0.2-200 ÁM. The toxic effect was associated with increased levels of intracellular phosphoprotein and subsequent release of inflammatory cytokines IL-6 and IL-8, while no release of TNF- was observed. Changes in intracellular phosphoprotein levels occurred at concentrations below the cytotoxic effect. IL-6 and IL-8 production increased up to 4.4-fold relative to controls. IL-6 and IL-8 are released from lung epithelium to recruit cells of the immune system to sites of tissue damage. Therefore, the observed effects of chromium(VI) and manganese in lung epithelial cells demonstrate a mechanism through which the toxicity of these metals to epithelial cells can result in recruitment of cells of the immune system."
54044,Sheffet et al. 1982,Cancer mortality in a pigment plant utilizing lead and zinc chromates,"Several studies of workers exposed to various forms of chromium compounds have suggested an increased incidence of respiratory cancers. Lead and zinc chromates were among the chromium compounds implicated. The Department of Preventive Medicine and Community Health of the New Jersey Medical School undertook a detailed mortality study of a pigment plant in Newark which utilized both of these compounds. We compared observed deaths from each cause among 1296 white and 650 non-white males who were employed at the plant between January 1, 1940 and December 31, 1969, with expected deaths, as computed from cause-, age-, and time-specific standard death rates for the United States. A statistically significant relative risk of 1.6 for lung cancer among white male employees was found, as well as among the cohorts of white males employed 10 yr or more. A relative risk of 1.9 was noted for individuals employed at least 2 yr who were at least moderately exposed to chromates. An increased incidence of lung cancer among non-white males and stomach and pancreatic cancer among the total cohort was also evident. These data support the validity of the association between chromate pigment exposure and lung cancer, suggesting that pigment workers and other exposed to chromates be observed carefully in regard to possible risk or pancreatic and stomach cancers.","Cancer mortality in a pigment plant utilizing lead and zinc chromates Abs: Several studies of workers exposed to various forms of chromium compounds have suggested an increased incidence of respiratory cancers. Lead and zinc chromates were among the chromium compounds implicated. The Department of Preventive Medicine and Community Health of the New Jersey Medical School undertook a detailed mortality study of a pigment plant in Newark which utilized both of these compounds. We compared observed deaths from each cause among 1296 white and 650 non-white males who were employed at the plant between January 1, 1940 and December 31, 1969, with expected deaths, as computed from cause-, age-, and time-specific standard death rates for the United States. A statistically significant relative risk of 1.6 for lung cancer among white male employees was found, as well as among the cohorts of white males employed 10 yr or more. A relative risk of 1.9 was noted for individuals employed at least 2 yr who were at least moderately exposed to chromates. An increased incidence of lung cancer among non-white males and stomach and pancreatic cancer among the total cohort was also evident. These data support the validity of the association between chromate pigment exposure and lung cancer, suggesting that pigment workers and other exposed to chromates be observed carefully in regard to possible risk or pancreatic and stomach cancers."
52210,Nestmann et al. 1979,Detection of the mutagenic activity of lead chromate using a battery of microbial tests,"The potential mutagenicity of the carcinogen lead chromate was tested by the following battery of microbial tests: the Escherichia coli PolA+/PolA- survival test; the Salmonella/microsome His+ reversion assay; the E. coli Trp+ reversion test as a plate assay; the E. coli Gal+ forward mutation test; and the Saccharomyces cerevisiae assay for mitotic recombination. Lead chromate is mutagenic in Salmonella and in Saccharomyces and is thus identified as a microbial mutagen by this battery. Metabolic activation by rat liver homogenate (S9) is not required for the mutagenic activity of lead chromate. The most statistically significant, positive result is found with a supplementary assay, the E. coli fluctuation test. To determine whether the lead ion and/or the chromate ion were responsible for the mutagenicity observed, lead chloride and chromium trioxide (chromic acid) were also tested. In E. coli fluctuation test, the ranges of maximal mutagenicity for chromium trioxide and lead chromate overlap at the concentration 10(-5)M, whereas lead chloride shows no mutagenicity and little lethality at concentrations up to 10(-3)M. Thus, it appears that the chromate ion is responsible for the mutagenicity of lead chromate.","Detection of the mutagenic activity of lead chromate using a battery of microbial tests Abs: The potential mutagenicity of the carcinogen lead chromate was tested by the following battery of microbial tests: the Escherichia coli PolA+/PolA- survival test; the Salmonella/microsome His+ reversion assay; the E. coli Trp+ reversion test as a plate assay; the E. coli Gal+ forward mutation test; and the Saccharomyces cerevisiae assay for mitotic recombination. Lead chromate is mutagenic in Salmonella and in Saccharomyces and is thus identified as a microbial mutagen by this battery. Metabolic activation by rat liver homogenate (S9) is not required for the mutagenic activity of lead chromate. The most statistically significant, positive result is found with a supplementary assay, the E. coli fluctuation test. To determine whether the lead ion and/or the chromate ion were responsible for the mutagenicity observed, lead chloride and chromium trioxide (chromic acid) were also tested. In E. coli fluctuation test, the ranges of maximal mutagenicity for chromium trioxide and lead chromate overlap at the concentration 10(-5)M, whereas lead chloride shows no mutagenicity and little lethality at concentrations up to 10(-3)M. Thus, it appears that the chromate ion is responsible for the mutagenicity of lead chromate."
52159,Barltrop and  Meek 1979,Effect of particle size on lead absorption from the gut,"The relationship between particle size and absorption of lead particles from the gastrointestinal tract of the rat has been investigated. Preparations of metallic lead of particle size between 0 and 250 micron were incorporated in laboratory rat diets and absorption determined by measurement of tissue lead concentrations attined under standard conditions. An inverse relationship was found between particle size and lead absorption; this relationship was most marked in the 0 to 100 micron range. A five-fold enhancement of absorption was observed from the diet with lead particles of mean size 6 micron, compared with 197 micron particle size. Lead absorption from dried pain films containing lead chromate and lead octoate was measured using a similar technique. A marked enhancement of absorption was observed for both paints when particle size was reduced from 500 to 1,000 micron to less than 50 micron.","Effect of particle size on lead absorption from the gut Abs: The relationship between particle size and absorption of lead particles from the gastrointestinal tract of the rat has been investigated. Preparations of metallic lead of particle size between 0 and 250 micron were incorporated in laboratory rat diets and absorption determined by measurement of tissue lead concentrations attined under standard conditions. An inverse relationship was found between particle size and lead absorption; this relationship was most marked in the 0 to 100 micron range. A five-fold enhancement of absorption was observed from the diet with lead particles of mean size 6 micron, compared with 197 micron particle size. Lead absorption from dried pain films containing lead chromate and lead octoate was measured using a similar technique. A marked enhancement of absorption was observed for both paints when particle size was reduced from 500 to 1,000 micron to less than 50 micron."
51985,Adema and  Henzen 1989,A comparison of plant toxicities of some industrial chemicals in soil culture and soilless culture,"The toxicities of 10 industrial chemicals to three types of plants were determined according to OECD Guideline 208. Apart from two types of soil, soilless culture was used in the test. The results with terrestrial plants in these tests were also compared with those of the same chemicals tested with aquatic plants (duck weed, algae) in nutrient solution. It was found that in soilless culture the EC50 values obtained were much lower than those in soil culture. Soilless culture of terrestrial plants and tests with aquatic plants yielded about the same results, It is concluded that adsorption of the chemicals to soil particles is the main factor governing the results. In an additional experiment with Cd, it was demonstrated that the Cd content of reacting plants was about the same in tests carried out in soil and in nutrient solution, pointing to the obvious fact that the amount of chemical taken up is the basis for the toxic effect. In the interpretation of tests carried out with chemicals added directly to soil, this should be taken into account. It is recommended that soilless culture of terrestrial plants be seriously considered in ecotoxicological testing.","A comparison of plant toxicities of some industrial chemicals in soil culture and soilless culture Abs: The toxicities of 10 industrial chemicals to three types of plants were determined according to OECD Guideline 208. Apart from two types of soil, soilless culture was used in the test. The results with terrestrial plants in these tests were also compared with those of the same chemicals tested with aquatic plants (duck weed, algae) in nutrient solution. It was found that in soilless culture the EC50 values obtained were much lower than those in soil culture. Soilless culture of terrestrial plants and tests with aquatic plants yielded about the same results, It is concluded that adsorption of the chemicals to soil particles is the main factor governing the results. In an additional experiment with Cd, it was demonstrated that the Cd content of reacting plants was about the same in tests carried out in soil and in nutrient solution, pointing to the obvious fact that the amount of chemical taken up is the basis for the toxic effect. In the interpretation of tests carried out with chemicals added directly to soil, this should be taken into account. It is recommended that soilless culture of terrestrial plants be seriously considered in ecotoxicological testing."
51967,Centeno et al. 1995,Cyst-based toxicity tests IX The potential of thamnocephalus platyurus as test species in comparison with Streptocephalus proboscideus (Crustacea: Branchiopoda: Anostraca),"The potential of the larvae of the freshwater anostracan crustacean Thamnocephalus platyurus has been evaluated as an alternative to those of the related species Streptocephalus proboscideus, used so far as the test organism in the standard Streptoxkit F test. In line with the former cyst-based toxicity test method, the hatching of dried T. platyurus eggs, the molting of larvae, and the sensitivity of the fatter to toxicants were assessed. The acute toxicity of 10 pure chemicals, 4 solid waste leachates, and 5 sediment pore waters to T. platyurus nauplii was determined according to the standard Streptoxkit F test protocol. Hatching success and reliability of T. platyurus cysts proved better than that of S. proboscideus cysts after 20 h incubation in standard conditions; the hatching percentage after 24 h was slightly improved by diluting the Environmental Protection Agency medium to 1:8 with deionized water. The sensitivity of T. platyurus nauplii to pure toxicants and wastes was at least equal to, and in many cases even higher than, that of S. proboscideus larvae. Generally, precision of the toxicity tests with T. platyurus was better than that of the S. proboscideus assay, especially for the pure chemicals tested. Consequently, the standard operational testing protocol of the Streptoxkit F has been slightly modified with replacement of S. proboscideus by T. platyurus as a test species. The Streptoxkit F has consequently been renamed to Thamnotoxkit F for use in cost-effective routine acute toxicity testing of chemicals and wastes.","Cyst-based toxicity tests IX The potential of thamnocephalus platyurus as test species in comparison with Streptocephalus proboscideus (Crustacea: Branchiopoda: Anostraca) Abs: The potential of the larvae of the freshwater anostracan crustacean Thamnocephalus platyurus has been evaluated as an alternative to those of the related species Streptocephalus proboscideus, used so far as the test organism in the standard Streptoxkit F test. In line with the former cyst-based toxicity test method, the hatching of dried T. platyurus eggs, the molting of larvae, and the sensitivity of the fatter to toxicants were assessed. The acute toxicity of 10 pure chemicals, 4 solid waste leachates, and 5 sediment pore waters to T. platyurus nauplii was determined according to the standard Streptoxkit F test protocol. Hatching success and reliability of T. platyurus cysts proved better than that of S. proboscideus cysts after 20 h incubation in standard conditions; the hatching percentage after 24 h was slightly improved by diluting the Environmental Protection Agency medium to 1:8 with deionized water. The sensitivity of T. platyurus nauplii to pure toxicants and wastes was at least equal to, and in many cases even higher than, that of S. proboscideus larvae. Generally, precision of the toxicity tests with T. platyurus was better than that of the S. proboscideus assay, especially for the pure chemicals tested. Consequently, the standard operational testing protocol of the Streptoxkit F has been slightly modified with replacement of S. proboscideus by T. platyurus as a test species. The Streptoxkit F has consequently been renamed to Thamnotoxkit F for use in cost-effective routine acute toxicity testing of chemicals and wastes."
51515,Nakamura et al. 1987,SOS-inducing activity of chemical carcinogens and mutagens in Salmonella typhimurium TA1535/pSK1002: Examination of 151 chemicals,"Summary The umu test system is a newly developed method to evaluate genotoxic activities of a wide variety of environmental carcinogens and mutagens (Oda et al., 1985). In the present study, we further examined the abilities of 151 chemicals to induce umu gene expression in Salmonella typhimurium TA1535/pSKlOO2. Among the chemicals examined, 72 compounds induced umu gene expression, which could be defined on a basis of increased ?-galactosidase activity by 2-fold over the background level. The potent genotoxic compounds without metabolic activation were adriamycin, bleomycin, daunorubicin, 1 ,3-dinitropyrene,1 ,6-dinitropyrene, 1 ,8-dinitropyrene, N-ethyl-N '-nitro-N-nitrosoguanidine, furylfuramide, methyl methanesulfonate, N-methyl-N '-nitro-N-nitrosoguanidine, mitomycin C, 1 -nitropyrene and 4-nitroquinoline-l-oxide. In the presence of S9, aflatoxin B1, 2-aminoanthracene, Glu-P-l, IQ, MeIQ, MeIQx, Trp-P-1and Trp-P-2 also induced umu gene expression markedly. Several chemicals such as 2-acetylaminofluorene, 9-aminoacridine, azobenzene, benzanthracene, benzidine, diethyl nitrosamine, l-nitronaphthalene, paraquat, potassium dichromate and sodium nitrite were weakly genotoxic and the induction by these compounds could be detected only when the incubation time was prolonged from 2 h to 5 h. Data are also presented that some of the chemicals such as dimethyl sulfoxide, m-dioxan, 5-fluorouracil and paraquat, which have been reported to be non-mutagenic in Ames/Salmonella assay, were found to be active in inducing umu gene expression, while the known mutagenic compounds including acrylonitrile, 4,4' -dinitrobiphenyl, furfural, methylene chloride, 1-naphthylamine, sodium azide, o-tolidine and o-toluidine were non-genotoxic in the present assay system.","SOS-inducing activity of chemical carcinogens and mutagens in Salmonella typhimurium TA1535/pSK1002: Examination of 151 chemicals Abs: Summary The umu test system is a newly developed method to evaluate genotoxic activities of a wide variety of environmental carcinogens and mutagens (Oda et al., 1985). In the present study, we further examined the abilities of 151 chemicals to induce umu gene expression in Salmonella typhimurium TA1535/pSKlOO2. Among the chemicals examined, 72 compounds induced umu gene expression, which could be defined on a basis of increased ?-galactosidase activity by 2-fold over the background level. The potent genotoxic compounds without metabolic activation were adriamycin, bleomycin, daunorubicin, 1 ,3-dinitropyrene,1 ,6-dinitropyrene, 1 ,8-dinitropyrene, N-ethyl-N '-nitro-N-nitrosoguanidine, furylfuramide, methyl methanesulfonate, N-methyl-N '-nitro-N-nitrosoguanidine, mitomycin C, 1 -nitropyrene and 4-nitroquinoline-l-oxide. In the presence of S9, aflatoxin B1, 2-aminoanthracene, Glu-P-l, IQ, MeIQ, MeIQx, Trp-P-1and Trp-P-2 also induced umu gene expression markedly. Several chemicals such as 2-acetylaminofluorene, 9-aminoacridine, azobenzene, benzanthracene, benzidine, diethyl nitrosamine, l-nitronaphthalene, paraquat, potassium dichromate and sodium nitrite were weakly genotoxic and the induction by these compounds could be detected only when the incubation time was prolonged from 2 h to 5 h. Data are also presented that some of the chemicals such as dimethyl sulfoxide, m-dioxan, 5-fluorouracil and paraquat, which have been reported to be non-mutagenic in Ames/Salmonella assay, were found to be active in inducing umu gene expression, while the known mutagenic compounds including acrylonitrile, 4,4' -dinitrobiphenyl, furfural, methylene chloride, 1-naphthylamine, sodium azide, o-tolidine and o-toluidine were non-genotoxic in the present assay system."
51507,Mendelsohn et al. 1992,A method for comparing and combining short-term genotoxicity test data: results and interpretation,"In the previous papers in this series, we describe a general approach toward creating a composite scoring system for genotoxicity testing. The method combines dose, metabolic activation and sign of outcome information in a way that accommodates negative and positive outcomes. It organizes the data hierarchically into replicates within a given test, tests within a class, classes within families, and finally families within a single agent score for each chemical (Lohman et al., 1992). We developed an optimized method to use dose information in such a system (Moore et al, 1992), and we applied the method to a sizab1e dataset prepared by Waters et al. (1988) for the International Agency for Research on Cancer (IARC). This paper summarizes and tries to interpret the overall behavior of the system, including the relationships among its components, its statistical properties, our understanding of its mechanisms, its potential for future development, and what it might be telling us about environmental mutagenicity testing. Detailed chemical results will be presented in later papers, as will the relationship of the present data to the corresponding system that has been developed for carcinogenesis (Nesnow, 1990). The experience to be described is limited to using the system to estimate general genotoxicity; the system has yet to be adapted or applied to other targets such as genotoxicity in the contexts of carcinogenicity or heritable mutation.","A method for comparing and combining short-term genotoxicity test data: results and interpretation Abs: In the previous papers in this series, we describe a general approach toward creating a composite scoring system for genotoxicity testing. The method combines dose, metabolic activation and sign of outcome information in a way that accommodates negative and positive outcomes. It organizes the data hierarchically into replicates within a given test, tests within a class, classes within families, and finally families within a single agent score for each chemical (Lohman et al., 1992). We developed an optimized method to use dose information in such a system (Moore et al, 1992), and we applied the method to a sizab1e dataset prepared by Waters et al. (1988) for the International Agency for Research on Cancer (IARC). This paper summarizes and tries to interpret the overall behavior of the system, including the relationships among its components, its statistical properties, our understanding of its mechanisms, its potential for future development, and what it might be telling us about environmental mutagenicity testing. Detailed chemical results will be presented in later papers, as will the relationship of the present data to the corresponding system that has been developed for carcinogenesis (Nesnow, 1990). The experience to be described is limited to using the system to estimate general genotoxicity; the system has yet to be adapted or applied to other targets such as genotoxicity in the contexts of carcinogenicity or heritable mutation."
51387,De Flora 1979,Metabolic activation and deactivation of mutagens and carcinogens,"INTRODUCTION A high correlation has been demonstrated between carcinogenicity of chemicals and their mutagenicity in the Salmonella/microsome test (Ames et al., 1973). However, some discrepancies have been detected, limiting the significance of this assay as an exclusive predictive model for the identification of carcinogens. These discrepancies are due either to carcinogens negative in the test (so called false negatives) or, more frequently, to non-carcinogens which are positive in the test (false positives) (McCann et al., 1975; Purchase et al., 1976; Yahagi et al., 1978). As discussed in detail by McCann and Ames (1976, 1977), most false positives and negatives can be ascribed either inadequacy of animal carcinogenicity tests or to differences between in vivo and in vitro metabolic pathways. Metabolic activation is simply yet efficiently obtained in the Ames test by incubating directly on Petri plates the compounds to be tested, the Salmonella tester strains, and rat liver homogenates together with a NADPH-generating system (Ames et al., 1973). Additionally, other preparations from different animal tissues have been also suggested (Ames et al., 1975) and have been applied to the standard procedure in order to check the metabolic behaviour of mutagens (Ficsor et al., 1977; McCoy et al.,1977; Petrilli and De Flora, l978a and 1978b). A previous study (De Flora, 1978) has shown that some mutagens, and particularly non-carcinogenic mutagens, can undergo a partial or complete metabolic deactivation when incubated together with rat liver microsomal preparations, thus mimicking the detoxification processes which occur in vivo in the liver. The present paper deals with further investigations, aiming at assessing the in vitro metabolic behaviour of a number of mutagens, including pure chemicals and also largely used products containing mutagenic chemicals, such as laboratory reagents and drugs. The results obtained have been correlated with the findings of the animal carcinogenicity tests reported in the literature.","Metabolic activation and deactivation of mutagens and carcinogens Abs: INTRODUCTION A high correlation has been demonstrated between carcinogenicity of chemicals and their mutagenicity in the Salmonella/microsome test (Ames et al., 1973). However, some discrepancies have been detected, limiting the significance of this assay as an exclusive predictive model for the identification of carcinogens. These discrepancies are due either to carcinogens negative in the test (so called false negatives) or, more frequently, to non-carcinogens which are positive in the test (false positives) (McCann et al., 1975; Purchase et al., 1976; Yahagi et al., 1978). As discussed in detail by McCann and Ames (1976, 1977), most false positives and negatives can be ascribed either inadequacy of animal carcinogenicity tests or to differences between in vivo and in vitro metabolic pathways. Metabolic activation is simply yet efficiently obtained in the Ames test by incubating directly on Petri plates the compounds to be tested, the Salmonella tester strains, and rat liver homogenates together with a NADPH-generating system (Ames et al., 1973). Additionally, other preparations from different animal tissues have been also suggested (Ames et al., 1975) and have been applied to the standard procedure in order to check the metabolic behaviour of mutagens (Ficsor et al., 1977; McCoy et al.,1977; Petrilli and De Flora, l978a and 1978b). A previous study (De Flora, 1978) has shown that some mutagens, and particularly non-carcinogenic mutagens, can undergo a partial or complete metabolic deactivation when incubated together with rat liver microsomal preparations, thus mimicking the detoxification processes which occur in vivo in the liver. The present paper deals with further investigations, aiming at assessing the in vitro metabolic behaviour of a number of mutagens, including pure chemicals and also largely used products containing mutagenic chemicals, such as laboratory reagents and drugs. The results obtained have been correlated with the findings of the animal carcinogenicity tests reported in the literature."
51352,Brams et al. 1987,"A comparative study, with 40 chemicals, of the efficiency of the Salmonella assay and the SOS chromotest (kit procedure)","A comparison was made, for 40 compounds belonging to different chemical classes, of the mutagenicity as measured by the Salmonella assay and of the SOS-inducing potency as measured by the SOS chromotest kit procedure. It was found that most (78%) of the chemicals described as mutagens/carcinogens (14 compounds) were detected with a simplified Ames test procedure, using 3 strains (TA 97, TA 98, TA 100) and 3 concentrations of the tested material. The SOS chromotest, carried out following the recommendations of the commercially available kits, revealed that only 4 Ames test-positive compounds were mutagenic towards E. coli strain PQ 37.","A comparative study, with 40 chemicals, of the efficiency of the Salmonella assay and the SOS chromotest (kit procedure) Abs: A comparison was made, for 40 compounds belonging to different chemical classes, of the mutagenicity as measured by the Salmonella assay and of the SOS-inducing potency as measured by the SOS chromotest kit procedure. It was found that most (78%) of the chemicals described as mutagens/carcinogens (14 compounds) were detected with a simplified Ames test procedure, using 3 strains (TA 97, TA 98, TA 100) and 3 concentrations of the tested material. The SOS chromotest, carried out following the recommendations of the commercially available kits, revealed that only 4 Ames test-positive compounds were mutagenic towards E. coli strain PQ 37."
51345,Bjørge et al. 1996,A comparative study of chemically induced DNA damage in isolated human and rat testicular cells,"Testicular cells prepared from human organ transplant donors or from Wistar rats were used to compare 15 known reproductive toxicants with respect to their ability to induce DNA damage, measured as single-strand DNA breaks and alkali labile sites (ssDNA breaks) with alkaline filter elution. The compounds tested included various categories of chemicals (i.e., pesticides, industrial chemicals, cytostatics, and mycotoxins) most of which are directly acting genotoxicants (i.e., reacting with DNA either spontaneously or via metabolic activation). In addition, a few indirect genotoxic and nongenotoxic reproductive toxicants were included. Six of the chemicals induced no significant levels of ssDNA breaks in human and rat testicular cells: methoxychlor (10 to 100 ÁM, human and rat), benomyl (10 to 100 ÁM, human and rat), thiotepa (10 to 1000 ÁM, human and rat), cisplatin (30 to 1000 ÁM, human; 100 to 1000 ÁM, rat), Cd2+ (30 to 1000 ÁM, human; 100 to 1000 ÁM, rat), and acrylonitrile (30 to 1000 ÁM, human; 30 to 300 ÁM, rat). Four chemicals induced significant levels of ssDNA breaks in testicular cells from both species: styrene oxide (>/= 100 ÁM, rat and human), 1,2-dibromoethane (EDB) (>/= 100 ÁM, rat; 1000 ÁM human), thiram (>/= 30 ÁM, rat; >/= 100 ÁM, human), and chlordecone (300 ÁM, rat; >/=300 ÁM, human). Finally, five chemicals induced ssDNA breaks in one of the two species. Four chemicals induced significant ssDNA breaks in rat testicular cells only: 1,2-dibromo-3-chloropropane (DBCP) (>/= 10 ÁM), 1,3-dinitrobenzene (1,3-DNB) (>/= 300 ÁM), Cr6+ (1000 ÁM, and aflatoxin B1 (>/= 100 ÁM), the last two of these produced only a minor positive response. One chemical, acrylamide, induced a marginal increase in ssDNA breaks in human at 1000 ÁM but not in rat testicular cells. Although based on a limited number of donors, the data indicate a close correlation between the induction of DNA damage in human and rat testicular cells in vitro. For some chemicals, however, there appears to be differences in the susceptibility to chemically induced ssDNA breaks of isolated testicular cells from the two species. The data indicate that the parallel use of human and rat testicular cells provides a valuable tool in the assessment of human testicular toxicity.","A comparative study of chemically induced DNA damage in isolated human and rat testicular cells Abs: Testicular cells prepared from human organ transplant donors or from Wistar rats were used to compare 15 known reproductive toxicants with respect to their ability to induce DNA damage, measured as single-strand DNA breaks and alkali labile sites (ssDNA breaks) with alkaline filter elution. The compounds tested included various categories of chemicals (i.e., pesticides, industrial chemicals, cytostatics, and mycotoxins) most of which are directly acting genotoxicants (i.e., reacting with DNA either spontaneously or via metabolic activation). In addition, a few indirect genotoxic and nongenotoxic reproductive toxicants were included. Six of the chemicals induced no significant levels of ssDNA breaks in human and rat testicular cells: methoxychlor (10 to 100 ÁM, human and rat), benomyl (10 to 100 ÁM, human and rat), thiotepa (10 to 1000 ÁM, human and rat), cisplatin (30 to 1000 ÁM, human; 100 to 1000 ÁM, rat), Cd2+ (30 to 1000 ÁM, human; 100 to 1000 ÁM, rat), and acrylonitrile (30 to 1000 ÁM, human; 30 to 300 ÁM, rat). Four chemicals induced significant levels of ssDNA breaks in testicular cells from both species: styrene oxide (>/= 100 ÁM, rat and human), 1,2-dibromoethane (EDB) (>/= 100 ÁM, rat; 1000 ÁM human), thiram (>/= 30 ÁM, rat; >/= 100 ÁM, human), and chlordecone (300 ÁM, rat; >/=300 ÁM, human). Finally, five chemicals induced ssDNA breaks in one of the two species. Four chemicals induced significant ssDNA breaks in rat testicular cells only: 1,2-dibromo-3-chloropropane (DBCP) (>/= 10 ÁM), 1,3-dinitrobenzene (1,3-DNB) (>/= 300 ÁM), Cr6+ (1000 ÁM, and aflatoxin B1 (>/= 100 ÁM), the last two of these produced only a minor positive response. One chemical, acrylamide, induced a marginal increase in ssDNA breaks in human at 1000 ÁM but not in rat testicular cells. Although based on a limited number of donors, the data indicate a close correlation between the induction of DNA damage in human and rat testicular cells in vitro. For some chemicals, however, there appears to be differences in the susceptibility to chemically induced ssDNA breaks of isolated testicular cells from the two species. The data indicate that the parallel use of human and rat testicular cells provides a valuable tool in the assessment of human testicular toxicity."
51033,Gage and  Litchfield 1968,The migration of lead from polymers in the rat gastro-intestinal tract,"The migration of lead (7439921) from four polymer formulations during passage through the gastrointestinal tract was studied in SPF-rats. The polymers were ground and fed to rats for 4 to 5 months at 1 percent of their diet. The formulations and lead component contents were: polythene, 0.4 percent lead-carbonate (598630); polyvinyl-chloride (PVC), 2.3 percent tribasic/lead-sulfate (7446142); polypropylene, 0.5 percent lead-chromate-molybdate; and rigid urethane foam, 0.07 percent lead-2-ethylhexoate (16996400). For controls, lead-nitrate (10099748) was added to diets to give an excess of 2, 6, or 20 parts per million (ppm), or standard diet was fed. Lead contents in livers, kidney, bone, blood, urine, and bile were assayed at various times. With 20ppm lead-nitrate, lead was increased in bone, kidney, and bile. With polythene, lead content in bone, as well as biliary excretion, increased toward the end of the study; the liver had an early increase in lead. With PVC, lead content of bones and kidneys increased early in the study and remained elevated; liver levels increased initially, and biliary excretion increased toward the end. No increases were noted with polypropylene or urethane. The authors conclude that bile is the best index of lead absorption. The risk of lead poisoning from ingestion of any of the four polymers is negligible.","The migration of lead from polymers in the rat gastro-intestinal tract Abs: The migration of lead (7439921) from four polymer formulations during passage through the gastrointestinal tract was studied in SPF-rats. The polymers were ground and fed to rats for 4 to 5 months at 1 percent of their diet. The formulations and lead component contents were: polythene, 0.4 percent lead-carbonate (598630); polyvinyl-chloride (PVC), 2.3 percent tribasic/lead-sulfate (7446142); polypropylene, 0.5 percent lead-chromate-molybdate; and rigid urethane foam, 0.07 percent lead-2-ethylhexoate (16996400). For controls, lead-nitrate (10099748) was added to diets to give an excess of 2, 6, or 20 parts per million (ppm), or standard diet was fed. Lead contents in livers, kidney, bone, blood, urine, and bile were assayed at various times. With 20ppm lead-nitrate, lead was increased in bone, kidney, and bile. With polythene, lead content in bone, as well as biliary excretion, increased toward the end of the study; the liver had an early increase in lead. With PVC, lead content of bones and kidneys increased early in the study and remained elevated; liver levels increased initially, and biliary excretion increased toward the end. No increases were noted with polypropylene or urethane. The authors conclude that bile is the best index of lead absorption. The risk of lead poisoning from ingestion of any of the four polymers is negligible."
50998,Boffetta 1993,Carcinogenicity of trace elements with reference to evaluations made by the International Agency for Research on Cancer,"The monograph program of the International Agency for Research of on Cancer has evaluated many trace elements for their carcinogenicity to humans. Five groups of compounds were considered human carcinogens: arsenic and arsenic compounds, beryllium and beryllium compounds, cadmium and cadmium compounds, hexavalent chromium compounds, and nickel compounds. Antimony trioxide, cobalt and cobalt compounds, lead and inorganic lead compounds, methylmercury compounds, and metallic nickel were considered possibly carcinogenic to humans. Antimony trisulfide, trivalent chromium compounds, metallic chromium, ferric oxide, organolead compounds, metallic mercury, inorganic mercury compounds, selenium and selenium compounds, and titanium dioxide were not classifiable. Trace elements studied to a limited extent include copper, manganese, tin, vanadium, and zinc. Among the problems are the lack of relevant data, the definition of active species, the extrapolation of the results of experimental studies to humans, the methodological problems of epidemiologic studies, and the possible anticarcinogenic activity of some trace elements.","Carcinogenicity of trace elements with reference to evaluations made by the International Agency for Research on Cancer Abs: The monograph program of the International Agency for Research of on Cancer has evaluated many trace elements for their carcinogenicity to humans. Five groups of compounds were considered human carcinogens: arsenic and arsenic compounds, beryllium and beryllium compounds, cadmium and cadmium compounds, hexavalent chromium compounds, and nickel compounds. Antimony trioxide, cobalt and cobalt compounds, lead and inorganic lead compounds, methylmercury compounds, and metallic nickel were considered possibly carcinogenic to humans. Antimony trisulfide, trivalent chromium compounds, metallic chromium, ferric oxide, organolead compounds, metallic mercury, inorganic mercury compounds, selenium and selenium compounds, and titanium dioxide were not classifiable. Trace elements studied to a limited extent include copper, manganese, tin, vanadium, and zinc. Among the problems are the lack of relevant data, the definition of active species, the extrapolation of the results of experimental studies to humans, the methodological problems of epidemiologic studies, and the possible anticarcinogenic activity of some trace elements."
50811,Horowitz and  Finley 1994,Setting health-protective soil concentrations for dermal contact allergens: a proposed methodology,"Health-based cleanup goals for contaminated soils are typically established to protect potentially exposed individuals from increased incidences of cancer and serious noncancer effects. However, at least one regulatory agency has suggested that, for certain contact allergens such as hexavalent chromium, soil remedial goals should also consider the potential occurrence of allergic contact dermatitis (ACD) in sensitized individuals (NJDEPE, 1992). To date, appropriate risk assessment methods for setting ACD-based soil concentrations have not been addressed in the scientific literature. This paper defines and discusses the three key data needs for establishing ACD-based soil concentrations: (1) dose-response data from human patch-testing studies, in which the patch concentrations are reported in terms of mass of allergen per unit area of skin, (2) accurate estimates of the degree to which soil adheres to skin on a soil mass per unit area of skin basis, and (3) accurate estimates of the degree to which the allergen leaches from soil into human sweat. The requisite basis for each of these factors and suggested methods for obtaining and evaluating the necessary data are presented. In addition, two example calculations are presented for setting ACD-based goals for hexavalent and trivalent chromium in chromite ore-processing residues.","Setting health-protective soil concentrations for dermal contact allergens: a proposed methodology Abs: Health-based cleanup goals for contaminated soils are typically established to protect potentially exposed individuals from increased incidences of cancer and serious noncancer effects. However, at least one regulatory agency has suggested that, for certain contact allergens such as hexavalent chromium, soil remedial goals should also consider the potential occurrence of allergic contact dermatitis (ACD) in sensitized individuals (NJDEPE, 1992). To date, appropriate risk assessment methods for setting ACD-based soil concentrations have not been addressed in the scientific literature. This paper defines and discusses the three key data needs for establishing ACD-based soil concentrations: (1) dose-response data from human patch-testing studies, in which the patch concentrations are reported in terms of mass of allergen per unit area of skin, (2) accurate estimates of the degree to which soil adheres to skin on a soil mass per unit area of skin basis, and (3) accurate estimates of the degree to which the allergen leaches from soil into human sweat. The requisite basis for each of these factors and suggested methods for obtaining and evaluating the necessary data are presented. In addition, two example calculations are presented for setting ACD-based goals for hexavalent and trivalent chromium in chromite ore-processing residues."
50704,Domingo 1994,Metal-induced developmental toxicity in mammals: A review,"It is well established that certain metals are toxic to embryonic and fetal tissues and can induce teratogenicity in mammals. The main objective of this paper has been to summarize the toxic effects that excesses of certain metals may cause on mammalian development. The reviewed elements have been divided into four groups: (a) metals of greatest toxicological significance (arsenic, cadmium, lead, mercury, and uranium) that are wide-spread in the human environment, (b) essential trace metals (chromium, cobalt, manganese, selenium, and zinc), (c) other metals with evident biological interest (nickel and vanadium), and (d) metals of pharmacological interest (aluminum, gallium, and lithium). A summary of the therapeutic use of chelating agents in the prevention of metal-induced developmental toxicity has also been included. meso-2,3-Dimercaptosuccinic acid (DMSA) and sodium 2,3-dimercaptopropane-1-sulfonate (DMPS) have been reported to be effective in alleviating arsenic- and mercury-induced teratogenesis, whereas sodium 4,5-dihydroxybenzene-1,3-disulfonate (Tiron) would protect against vanadium- and uranium-induced developmental toxicity.","Metal-induced developmental toxicity in mammals: A review Abs: It is well established that certain metals are toxic to embryonic and fetal tissues and can induce teratogenicity in mammals. The main objective of this paper has been to summarize the toxic effects that excesses of certain metals may cause on mammalian development. The reviewed elements have been divided into four groups: (a) metals of greatest toxicological significance (arsenic, cadmium, lead, mercury, and uranium) that are wide-spread in the human environment, (b) essential trace metals (chromium, cobalt, manganese, selenium, and zinc), (c) other metals with evident biological interest (nickel and vanadium), and (d) metals of pharmacological interest (aluminum, gallium, and lithium). A summary of the therapeutic use of chelating agents in the prevention of metal-induced developmental toxicity has also been included. meso-2,3-Dimercaptosuccinic acid (DMSA) and sodium 2,3-dimercaptopropane-1-sulfonate (DMPS) have been reported to be effective in alleviating arsenic- and mercury-induced teratogenesis, whereas sodium 4,5-dihydroxybenzene-1,3-disulfonate (Tiron) would protect against vanadium- and uranium-induced developmental toxicity."
50324,Wise et al. 1993,Inhibition of lead chromate clastogenesis by ascorbate: relationship to particle dissolution and uptake,"#Chromium metal salts are considered to be human carcinogens, especially the salts of low solubility. Lead chromate, a highly insoluble chromium metal salt, has been shown to be tumorigenic, genotoxic and clastogenic. In this study, the roles of particle-cell contact, particle dissolution and particle uptake in the clastogenic activity of lead chromate were investigated. Using Pb51CrO4 it was found that lead chromate particles (1.2 microns mean diameter, -28 mV surface charge) were slightly soluble in water; solubility increased 2-fold when particles were incubated in culture medium, but was not increased further by the addition of serum. The extracellular concentration of chromium increased 7-fold when lead chromate was incubated in the presence of Chinese hamster ovary (CHO) cells compared with culture medium alone. The intracellular concentration of ionic chromium increased in a dose-dependent manner following exposure of CHO cells to clastogenic doses of lead chromate reaching estimated levels as high as 1.2 mM per cell. Treatment of cells with lead chromate particles in the presence of a nontoxic dose of vitamin C blocked uptake of ionic chromium and eliminated the clastogenic activity of the particles. Transmission electron microscopy showed that lead chromate particles were internalized by CHO cells in phagocytic vacuoles in as little as 1 h; internalization was unaffected by co-treatment with vitamin C. It was demonstrated that particle-cell contact was required for lead chromate-induced clastogenesis. These data show that although phagocytic particle uptake occurs, particle-cell contact and extracellular dissolution are responsible for the clastogenic activity of lead chromate. These data also demonstrate that the genotoxicity of particulate hexavalent chromates can be blocked by vitamin C.","Inhibition of lead chromate clastogenesis by ascorbate: relationship to particle dissolution and uptake Abs: #Chromium metal salts are considered to be human carcinogens, especially the salts of low solubility. Lead chromate, a highly insoluble chromium metal salt, has been shown to be tumorigenic, genotoxic and clastogenic. In this study, the roles of particle-cell contact, particle dissolution and particle uptake in the clastogenic activity of lead chromate were investigated. Using Pb51CrO4 it was found that lead chromate particles (1.2 microns mean diameter, -28 mV surface charge) were slightly soluble in water; solubility increased 2-fold when particles were incubated in culture medium, but was not increased further by the addition of serum. The extracellular concentration of chromium increased 7-fold when lead chromate was incubated in the presence of Chinese hamster ovary (CHO) cells compared with culture medium alone. The intracellular concentration of ionic chromium increased in a dose-dependent manner following exposure of CHO cells to clastogenic doses of lead chromate reaching estimated levels as high as 1.2 mM per cell. Treatment of cells with lead chromate particles in the presence of a nontoxic dose of vitamin C blocked uptake of ionic chromium and eliminated the clastogenic activity of the particles. Transmission electron microscopy showed that lead chromate particles were internalized by CHO cells in phagocytic vacuoles in as little as 1 h; internalization was unaffected by co-treatment with vitamin C. It was demonstrated that particle-cell contact was required for lead chromate-induced clastogenesis. These data show that although phagocytic particle uptake occurs, particle-cell contact and extracellular dissolution are responsible for the clastogenic activity of lead chromate. These data also demonstrate that the genotoxicity of particulate hexavalent chromates can be blocked by vitamin C."
50275,Kano et al. 1993,Lung cancer mortality among a cohort of male chromate pigment workers in Japan,"In 1975, five manufacturers of chromate pigment in Japan were examined in a study of the carcinogenicity of chromates. These companies were producing lead chromate, zinc chromate, molybdate orange and/or strontium chromate. The current study covers a cohort of 666 workers involved in the manufacture of chromate pigment for at least 1 year between 1950 and 1975. The workers were followed up for 15-40 years, until 1989. Many previous reports have found an excess lung cancer risk among workers involved in the manufacture of chromate pigments and chromate chemicals. In the current study, subjects were classified on the basis of years worked, years of observation, characteristics of company, type of work engaged in for the longest period of time, and involvement in the manufacture of zinc chromate. Mortality was compared with that of all Japanese males by means of the person-year method. The route of exposure was primarily inhalation through the respiratory system. None of the results showed statistically significant differences that would suggest an excess risk for malignant neoplasms, particularly lung cancer, among workers engaged in the manufacture of chromate pigment in Japan.","Lung cancer mortality among a cohort of male chromate pigment workers in Japan Abs: In 1975, five manufacturers of chromate pigment in Japan were examined in a study of the carcinogenicity of chromates. These companies were producing lead chromate, zinc chromate, molybdate orange and/or strontium chromate. The current study covers a cohort of 666 workers involved in the manufacture of chromate pigment for at least 1 year between 1950 and 1975. The workers were followed up for 15-40 years, until 1989. Many previous reports have found an excess lung cancer risk among workers involved in the manufacture of chromate pigments and chromate chemicals. In the current study, subjects were classified on the basis of years worked, years of observation, characteristics of company, type of work engaged in for the longest period of time, and involvement in the manufacture of zinc chromate. Mortality was compared with that of all Japanese males by means of the person-year method. The route of exposure was primarily inhalation through the respiratory system. None of the results showed statistically significant differences that would suggest an excess risk for malignant neoplasms, particularly lung cancer, among workers engaged in the manufacture of chromate pigment in Japan."
50067,Manzo et al. 1992,Metabolic studies as a basis for the interpretation of metal toxicity,"The use of metabolic patterns as a basis for the interpretation of toxic effects of metal compounds was reviewed. Most metals were transformed in mammalian tissues by reduction/oxidation, conjugation, or alkylation/dealkylation processes. It occurred in liver and other organs as well as in the gut lumen in which case intestinal microflora were involved. Studies with mercurials showed that marked metabolic differences existed between organic (alkyl, aryl, and alkoxyalkyl) and inorganic compounds. The lower toxicity of the last two types was due to their rapid conversion to inorganic mercury (7439976) which was mediated by a cytosolic enzyme in the liver. The reduction of hexavalent chromium (7440473) to the trivalent form by both rat liver preparations and human erythrocyte lysate through the microsomal system was discussed. The involvement of cytochrome-P450 dependent monoxygenases in the conversion of tin (7440315) and lead (7439921) compounds was addressed. The biotransformation of arsenic (7440382) was strikingly different between species. The metabolism of inorganic and certain organic selenium (7782492) compounds in mammals was based on common pathways. Theoretically, the biotransformation of metal could alter toxicity or kinetics, or both. Conjugation with glutathione could activate or reduce carcinogenic potential. Examples of pollutant metals, their metabolism and associated toxic effects included the demethylation of methyl-mercury (22967926) and neurotoxicity, the immunotoxicity of tributyltin (688733) and its neurotoxic effects, the limited biochemical reduction of pentavalent vanadium (7440622) to the tetravalent form, and the unreduced vanadate causing toxicity, and the reduction of pentavalent arsenic to the trivalent carcinogenic form. The authors conclude that a better knowledge of metal biotransformation can lead to significant advances in interpreting toxicological changes.","Metabolic studies as a basis for the interpretation of metal toxicity Abs: The use of metabolic patterns as a basis for the interpretation of toxic effects of metal compounds was reviewed. Most metals were transformed in mammalian tissues by reduction/oxidation, conjugation, or alkylation/dealkylation processes. It occurred in liver and other organs as well as in the gut lumen in which case intestinal microflora were involved. Studies with mercurials showed that marked metabolic differences existed between organic (alkyl, aryl, and alkoxyalkyl) and inorganic compounds. The lower toxicity of the last two types was due to their rapid conversion to inorganic mercury (7439976) which was mediated by a cytosolic enzyme in the liver. The reduction of hexavalent chromium (7440473) to the trivalent form by both rat liver preparations and human erythrocyte lysate through the microsomal system was discussed. The involvement of cytochrome-P450 dependent monoxygenases in the conversion of tin (7440315) and lead (7439921) compounds was addressed. The biotransformation of arsenic (7440382) was strikingly different between species. The metabolism of inorganic and certain organic selenium (7782492) compounds in mammals was based on common pathways. Theoretically, the biotransformation of metal could alter toxicity or kinetics, or both. Conjugation with glutathione could activate or reduce carcinogenic potential. Examples of pollutant metals, their metabolism and associated toxic effects included the demethylation of methyl-mercury (22967926) and neurotoxicity, the immunotoxicity of tributyltin (688733) and its neurotoxic effects, the limited biochemical reduction of pentavalent vanadium (7440622) to the tetravalent form, and the unreduced vanadate causing toxicity, and the reduction of pentavalent arsenic to the trivalent carcinogenic form. The authors conclude that a better knowledge of metal biotransformation can lead to significant advances in interpreting toxicological changes."
49683,Xu et al. 1992,DNA damage induced by carcinogenic lead chromate particles in cultured mammalian cells,"Particulate lead chromate is a highly water-insoluble cytotoxic and carcinogenic agent, but its mechanism of action remains obscure. We investigated its effects on DNA damage in CHO cells after a 24-h exposure using alkaline or neutral filter elution and cytogenetic studies. Concentrations (0.08, 0.4 and 0.8 micrograms/cm2), which reduced the colony-forming efficiency of CHO cells to 94, 50 and 10%, respectively, produced dose-dependent DNA single-strand breaks and DNA-protein crosslinks, but no DNA double-strand breaks or DNA-DNA crosslinks were observed. The single-strand breaks were absent from cells given a 24-h recovery period after removal of the treatment medium, even though most of the particles remained adhered to cells and to the culture dish. In contrast, both the DNA-protein crosslinks and chromosomal aberrations persisted even after the 24-h recovery period. These results suggest that the mechanism of the particle-induced early DNA single-strand breaks may be different from DNA-protein crosslinks and the lesions leading to chromosomal aberrations, or alternatively, that the repair of single-strand breaks is more efficient than the repair of DNA-protein crosslinks in the unavoidable continuing presence of carcinogen. These results also suggest that the chromosome damage may be related to the persistent DNA-protein crosslinks, and further confirm the genotoxic activity of carcinogenic lead chromate particles.","DNA damage induced by carcinogenic lead chromate particles in cultured mammalian cells Abs: Particulate lead chromate is a highly water-insoluble cytotoxic and carcinogenic agent, but its mechanism of action remains obscure. We investigated its effects on DNA damage in CHO cells after a 24-h exposure using alkaline or neutral filter elution and cytogenetic studies. Concentrations (0.08, 0.4 and 0.8 micrograms/cm2), which reduced the colony-forming efficiency of CHO cells to 94, 50 and 10%, respectively, produced dose-dependent DNA single-strand breaks and DNA-protein crosslinks, but no DNA double-strand breaks or DNA-DNA crosslinks were observed. The single-strand breaks were absent from cells given a 24-h recovery period after removal of the treatment medium, even though most of the particles remained adhered to cells and to the culture dish. In contrast, both the DNA-protein crosslinks and chromosomal aberrations persisted even after the 24-h recovery period. These results suggest that the mechanism of the particle-induced early DNA single-strand breaks may be different from DNA-protein crosslinks and the lesions leading to chromosomal aberrations, or alternatively, that the repair of single-strand breaks is more efficient than the repair of DNA-protein crosslinks in the unavoidable continuing presence of carcinogen. These results also suggest that the chromosome damage may be related to the persistent DNA-protein crosslinks, and further confirm the genotoxic activity of carcinogenic lead chromate particles."
49290,Wise et al. 1992,Clastogenicity of lead chromate particles in hamster and human cells,"#Several insoluble compounds of chromium, such as lead chromate, are respiratory carcinogens in experimental animals and suspected to be so in humans. Lead chromate induces neoplastic transformation in cultured cells but the mechanism of genotoxicity is unknown. We examined the effect of lead chromate on the integrity of chromosomes of Chinese hamster ovary (CHO) and human foreskin fibroblasts (HFF) after a 24-h exposure. At 0.4 microgram/cm2, 0.8 microgram/cm2, 2 microgram/cm2 and 8 microgram/cm2 lead chromate particles reduced survival of CHO cells to 86%, 62%, 2% and less than 1% respectively. These concentrations induced a dose-dependent 4-19-fold increase in the percent metaphases with damage. The HFF cells exhibited higher sensitivity in both cytotoxicity and clastogenicity. The spectrum of damage observed for both cell types was primarily achromatic lesions affecting one or both chromatids. To test for particle dissolution effects, CHO cells were treated for 24 h with either clarified medium that had been incubated for 24 h with lead chromate particles, or clarified medium that had been pre-conditioned by CHO cells treated with lead chromate particles for 24 h. No damage was detected in these cells, indicating that extracellular dissolution into ionic lead and chromate did not contribute to the genotoxicity. This is consistent with a previous study in which scanning electron micrographs illustrated internalization of the particles. These results suggest that clastogenesis may be a mechanism for lead chromate induced carcinogenesis.","Clastogenicity of lead chromate particles in hamster and human cells Abs: #Several insoluble compounds of chromium, such as lead chromate, are respiratory carcinogens in experimental animals and suspected to be so in humans. Lead chromate induces neoplastic transformation in cultured cells but the mechanism of genotoxicity is unknown. We examined the effect of lead chromate on the integrity of chromosomes of Chinese hamster ovary (CHO) and human foreskin fibroblasts (HFF) after a 24-h exposure. At 0.4 microgram/cm2, 0.8 microgram/cm2, 2 microgram/cm2 and 8 microgram/cm2 lead chromate particles reduced survival of CHO cells to 86%, 62%, 2% and less than 1% respectively. These concentrations induced a dose-dependent 4-19-fold increase in the percent metaphases with damage. The HFF cells exhibited higher sensitivity in both cytotoxicity and clastogenicity. The spectrum of damage observed for both cell types was primarily achromatic lesions affecting one or both chromatids. To test for particle dissolution effects, CHO cells were treated for 24 h with either clarified medium that had been incubated for 24 h with lead chromate particles, or clarified medium that had been pre-conditioned by CHO cells treated with lead chromate particles for 24 h. No damage was detected in these cells, indicating that extracellular dissolution into ionic lead and chromate did not contribute to the genotoxicity. This is consistent with a previous study in which scanning electron micrographs illustrated internalization of the particles. These results suggest that clastogenesis may be a mechanism for lead chromate induced carcinogenesis."
49229,Sagripanti et al. 1991,Interaction of copper with DNA and antagonism by other metals,"Binding of copper (7440508) (Cu) as the divalent ion to double stranded DNA (dsDNA) and single stranded DNA (ssDNA) and the effects of nine competitor ions on Cu(II) interactions were investigated in-vitro. Slurries of dsDNA-cellulose and and ssDNA-cellulose were incubated at room temperature with 50 to 700 micromolar Cu(II) for 1 hour. DNA solutions were incubated at room temperature with 10 to 400 micromolar Cu(II). Essential and nonessential metals were added to 150 micromolar Cu(II) and then dsDNA was added for incubation. The data indicated the existence of two kinds of copper binding sites in DNA. Saturation studies indicated an average of one Cu(II) molecule bound for every two nucleotides which is equivalent to 1.50 micromoles copper per milligram of dsDNA. There was an average copper binding site every three nucleotides in ssDNA, as compared with one average Cu(II) site every two bases in dsDNA. This indicated that appropriate DNA base pairing accounted for some of the Cu(II) binding. There was an apparent stability constant of 2.4x10(4) per mole for the Cu(II) binding sites in high abundance. Except for hexavalent chromium, which showed an apparent enhancement of copper binding to DNA, all metal antagonists were found to compete with binding of Cu(II) to DNA. These cations included divalent nickel, cadmium, magnesium, zinc, mercury, calcium, lead, and manganese, with antagonism increasing in the order shown. The authors suggest that the biological mechanisms underlying copper toxicity could be rooted in the binding of copper to specific sites within DNA.","Interaction of copper with DNA and antagonism by other metals Abs: Binding of copper (7440508) (Cu) as the divalent ion to double stranded DNA (dsDNA) and single stranded DNA (ssDNA) and the effects of nine competitor ions on Cu(II) interactions were investigated in-vitro. Slurries of dsDNA-cellulose and and ssDNA-cellulose were incubated at room temperature with 50 to 700 micromolar Cu(II) for 1 hour. DNA solutions were incubated at room temperature with 10 to 400 micromolar Cu(II). Essential and nonessential metals were added to 150 micromolar Cu(II) and then dsDNA was added for incubation. The data indicated the existence of two kinds of copper binding sites in DNA. Saturation studies indicated an average of one Cu(II) molecule bound for every two nucleotides which is equivalent to 1.50 micromoles copper per milligram of dsDNA. There was an average copper binding site every three nucleotides in ssDNA, as compared with one average Cu(II) site every two bases in dsDNA. This indicated that appropriate DNA base pairing accounted for some of the Cu(II) binding. There was an apparent stability constant of 2.4x10(4) per mole for the Cu(II) binding sites in high abundance. Except for hexavalent chromium, which showed an apparent enhancement of copper binding to DNA, all metal antagonists were found to compete with binding of Cu(II) to DNA. These cations included divalent nickel, cadmium, magnesium, zinc, mercury, calcium, lead, and manganese, with antagonism increasing in the order shown. The authors suggest that the biological mechanisms underlying copper toxicity could be rooted in the binding of copper to specific sites within DNA."
49160,Pier et al. 1991,Silica encapsulation reduces bioavailability,"BIOSIS COPYRIGHT: BIOL ABS. Lead chromate pigments can be encapsulated within an amorphous silica coating. This reduces both the chemical leachability and the biological availability of the constituents. The chromate moiety is inactive in in vitro mutagenicity assays, even in the presence of a strong chelating solubilizer under conditions where the unencapsulated material gives positive results. Rodent feeding studies demonstrate much reduced absorption of both lead and chromium from the encapsulated lead chromate compared to the analogous unencapsulated material. Encapsulation also reduces the leachability of both lead and chromium in tests used to define the applicable environmental disposal methods for lead chromate pigments. These findings have important implications for health and environmental issues surrounding the use of lead chromate as a pigment material.","Silica encapsulation reduces bioavailability Abs: BIOSIS COPYRIGHT: BIOL ABS. Lead chromate pigments can be encapsulated within an amorphous silica coating. This reduces both the chemical leachability and the biological availability of the constituents. The chromate moiety is inactive in in vitro mutagenicity assays, even in the presence of a strong chelating solubilizer under conditions where the unencapsulated material gives positive results. Rodent feeding studies demonstrate much reduced absorption of both lead and chromium from the encapsulated lead chromate compared to the analogous unencapsulated material. Encapsulation also reduces the leachability of both lead and chromium in tests used to define the applicable environmental disposal methods for lead chromate pigments. These findings have important implications for health and environmental issues surrounding the use of lead chromate as a pigment material."
49158,Elias et al. 1991,Role of solubilized chromium in the induction of morphological transformation of Syrian hamster embryo (SHE) cells by particulate chromium(VI) compounds,"Chromium(VI) compounds--Ca, Sr, Zn and Pb chromates--were studied for cytotoxicity and morphological transformation in Syrian hamster embryo (SHE) cells in relation to their solubilization in cell culture conditions and intracellular Cr concentration. Ca, Sr and Zn chromates were completely solubilized after 1 day of incubation in cell cultures; for Pb chromate, 20-36% Cr was solubilized only after 7 days. In two parallel transformation assays, the SHE cells were treated with suspensions or with corresponding supernatants (containing only solubilized Cr) of these compounds. A statistically significant relationship was observed between the Cr treatment concentration and the amount of Cr per cell, irrespective of the compound (except suspensions of Pb chromate). The cytotoxicity was due to extracellular solubilized chromium because treatments with either supernatants or suspensions of Ca, Sr and Zn chromates gave the same LC50 of 0.31 +/- 0.01 microgram Cr/ml. A clear dose-response relationship was observed for the induction of morphological transformation for each compound, either previously solubilized or in suspension. The expression of the transformation frequencies as a function of the Cr concentration/cell revealed that (i) the transformation frequency is dependent on the Cr concentration/cell irrespective of the Cr compound Ca, Sr or Zn chromate, (ii) the transformation frequency induced by solubilized Pb chromate is higher than that induced by the other compounds at the same concentration of Cr/cell. A double treatment with solutions of Cr and Pb at corresponding concentrations induced the same transformation frequency as the solubilized Pb chromate. The results show that the solubilization of particulate Cr(VI) compounds is a critical step for their cytotoxic and transforming activities; the intracellular soluble Cr is the sole causative agent of the transforming activity of Ca, Sr and Zn chromates, while Pb appears to act synergistically with Cr in inducing the transformation by Pb chromate.","Role of solubilized chromium in the induction of morphological transformation of Syrian hamster embryo (SHE) cells by particulate chromium(VI) compounds Abs: Chromium(VI) compounds--Ca, Sr, Zn and Pb chromates--were studied for cytotoxicity and morphological transformation in Syrian hamster embryo (SHE) cells in relation to their solubilization in cell culture conditions and intracellular Cr concentration. Ca, Sr and Zn chromates were completely solubilized after 1 day of incubation in cell cultures; for Pb chromate, 20-36% Cr was solubilized only after 7 days. In two parallel transformation assays, the SHE cells were treated with suspensions or with corresponding supernatants (containing only solubilized Cr) of these compounds. A statistically significant relationship was observed between the Cr treatment concentration and the amount of Cr per cell, irrespective of the compound (except suspensions of Pb chromate). The cytotoxicity was due to extracellular solubilized chromium because treatments with either supernatants or suspensions of Ca, Sr and Zn chromates gave the same LC50 of 0.31 +/- 0.01 microgram Cr/ml. A clear dose-response relationship was observed for the induction of morphological transformation for each compound, either previously solubilized or in suspension. The expression of the transformation frequencies as a function of the Cr concentration/cell revealed that (i) the transformation frequency is dependent on the Cr concentration/cell irrespective of the Cr compound Ca, Sr or Zn chromate, (ii) the transformation frequency induced by solubilized Pb chromate is higher than that induced by the other compounds at the same concentration of Cr/cell. A double treatment with solutions of Cr and Pb at corresponding concentrations induced the same transformation frequency as the solubilized Pb chromate. The results show that the solubilization of particulate Cr(VI) compounds is a critical step for their cytotoxic and transforming activities; the intracellular soluble Cr is the sole causative agent of the transforming activity of Ca, Sr and Zn chromates, while Pb appears to act synergistically with Cr in inducing the transformation by Pb chromate."
49044,Sidhu et al. 1991,"Induction of morphological transformation, anchorage-independent growth and plasminogen activators in non-tumorigenic human osteosarcoma cells by lead chromate","The possible carcinogenicity of insoluble chromium (VI) compound, PbCrO4, in human cells has been tested using a nontumorigenic human osteosarcoma cell line (HOS, TE 85). Electron microscopic studies show that PbCrO4 is phagocytosed by HOS cells and accumulates within the vacuoles in the cytoplasm. A number of cell lines have been isolated following multiple treatment of HOS cells with PbCrO4. These cell lines are morphologically different from HOS cells, form anchorage-independent colonies in soft agar and form quickly regressing small tumor nodules in athymic nude mice. The cellular and secreted plasminogen activator (PA) levels of 5 cell lines isolated after PbCrO4 treatment are increased up to 8 fold and up to 10 fold respectively as compared to untreated HOS controls. SDS-PAGE analysis in the presence of copolymerized substrates is consistent with increase in 55 kDa urokinase-type PA (u-PA) and 68 kDa tissue-type PA (t-PA). These results show that PbCrO4 treatment leads to stable phenotypic changes indicative of the transformation of HOS cells.","Induction of morphological transformation, anchorage-independent growth and plasminogen activators in non-tumorigenic human osteosarcoma cells by lead chromate Abs: The possible carcinogenicity of insoluble chromium (VI) compound, PbCrO4, in human cells has been tested using a nontumorigenic human osteosarcoma cell line (HOS, TE 85). Electron microscopic studies show that PbCrO4 is phagocytosed by HOS cells and accumulates within the vacuoles in the cytoplasm. A number of cell lines have been isolated following multiple treatment of HOS cells with PbCrO4. These cell lines are morphologically different from HOS cells, form anchorage-independent colonies in soft agar and form quickly regressing small tumor nodules in athymic nude mice. The cellular and secreted plasminogen activator (PA) levels of 5 cell lines isolated after PbCrO4 treatment are increased up to 8 fold and up to 10 fold respectively as compared to untreated HOS controls. SDS-PAGE analysis in the presence of copolymerized substrates is consistent with increase in 55 kDa urokinase-type PA (u-PA) and 68 kDa tissue-type PA (t-PA). These results show that PbCrO4 treatment leads to stable phenotypic changes indicative of the transformation of HOS cells."
49035,Katz 1991,The analytical biochemistry of chromium,"The essentiality and carcinogenicity of chromium depend on its chemical form. Oxidation state and solubility are particularly important in determining the biological effects of chromium compounds. For this reason, total chromium measurements are of little value in assessing its nutritional benefits or its toxicological hazards. Aqueous sodium carbonate-sodium hydroxide solutions have been successfully used for extracting hexavalent chromium from a variety of environmental and biological matrices while preserving its oxidation state. Typical recoveries are 90 to 105% in samples spiked with both trivalent and hexavalent chromium. Determination of hexavalent chromium after extraction with sodium carbonate-sodium hydroxide solution, coupled with the determination of total chromium after nitric acid-hydrogen peroxide digestion, has been applied to the evaluation of chromium speciation in airborne particulates, sludges, and biological tissues.","The analytical biochemistry of chromium Abs: The essentiality and carcinogenicity of chromium depend on its chemical form. Oxidation state and solubility are particularly important in determining the biological effects of chromium compounds. For this reason, total chromium measurements are of little value in assessing its nutritional benefits or its toxicological hazards. Aqueous sodium carbonate-sodium hydroxide solutions have been successfully used for extracting hexavalent chromium from a variety of environmental and biological matrices while preserving its oxidation state. Typical recoveries are 90 to 105% in samples spiked with both trivalent and hexavalent chromium. Determination of hexavalent chromium after extraction with sodium carbonate-sodium hydroxide solution, coupled with the determination of total chromium after nitric acid-hydrogen peroxide digestion, has been applied to the evaluation of chromium speciation in airborne particulates, sludges, and biological tissues."
49025,Essington and  Mattigod 1991,Trace element solid-phase associations in sewage sludge and sludge-amended soil,"BIOSIS COPYRIGHT: BIOL ABS. A scheme involving the use of particle size, density, and magnetic susceptibility was applied to sewage sludge and sewage-sludge-amended soil to isolate trace-element-bearing soils for identification by x-ray diffraction (XRD) and scanning electron microscopy/energy dispersive x-ray analysis (SEM). The heavy-density (> 2.96 Mg m-3) fractions of the sludge and amended soil contained barite, celestite, lead silicate, lead phosphate, chromium oxide or oxyhydroxide, sphalerite, and chalcopyrite. Vanadium was associated with Ti, Ca, Si, and Fe in amended soil particles, suggesting its occurrence in titanite. The heavy-density fractions also contained trace-element-bearing particles of industrial origin, including Sb, Cr-Fe, Cr-Ni-Fe, Zn-Sn, Cr-Zn-Fe, Sn-Fe-Cu-Zn, Pb-Cr, Pb-Sn, W-Se, and Co-Cr elemental associations. Trace-element-bearing particles contained in the light-density (2.10 Mg m-3) fractions of the sludge and sludge-amended soil were similar to those identif","Trace element solid-phase associations in sewage sludge and sludge-amended soil Abs: BIOSIS COPYRIGHT: BIOL ABS. A scheme involving the use of particle size, density, and magnetic susceptibility was applied to sewage sludge and sewage-sludge-amended soil to isolate trace-element-bearing soils for identification by x-ray diffraction (XRD) and scanning electron microscopy/energy dispersive x-ray analysis (SEM). The heavy-density (> 2.96 Mg m-3) fractions of the sludge and amended soil contained barite, celestite, lead silicate, lead phosphate, chromium oxide or oxyhydroxide, sphalerite, and chalcopyrite. Vanadium was associated with Ti, Ca, Si, and Fe in amended soil particles, suggesting its occurrence in titanite. The heavy-density fractions also contained trace-element-bearing particles of industrial origin, including Sb, Cr-Fe, Cr-Ni-Fe, Zn-Sn, Cr-Zn-Fe, Sn-Fe-Cu-Zn, Pb-Cr, Pb-Sn, W-Se, and Co-Cr elemental associations. Trace-element-bearing particles contained in the light-density (2.10 Mg m-3) fractions of the sludge and sludge-amended soil were similar to those identif"
48877,Sheehan et al. 1991,Assessment of the human health risks posed by exposure to chromium-contaminated soils,"Millions of tons of chromite-ore processing residue have been used as fill in various locations in northern New Jersey and elsewhere in the United States. The primary toxicants in the residue are trivalent chromium [Cr(III)] and hexavalent chromium [Cr(VI)]. The hazard posed by Cr(III) is negligible due to its low acute and chronic toxicity. In contrast, Cr(VI) is a human carcinogen following inhalation of high concentrations. It can also cause allergic contact dermatitis. This evaluation addresses a residential site where the arithmetic mean (x) and geometric mean (gm) concentrations of Cr(III) in soil were 2879 and 1212 mg/kg (ppm). The mean and geometric mean concentrations of Cr(VI) were 180 and 4 mg/kg, respectively. The uptake (absorbed dose) of Cr(III) via soil ingestion, consumption of homegrown vegetables, and ingestion of inspired particles was determined. The uptake of Cr(VI) via dermal absorption from contact with surface soil and building wall surfaces, as well as inhalation, was also evaluated. The techniques used in this assessment are applicable for evaluating the human health risks posed by any residential site having contaminated soil. The potential for both sensitized and unsensitized persons to develop allergic contact dermatitis due to exposure to soil contaminated at these levels was found to be negligible. The estimated average daily dose (ADD) via ingestion and dermal absorption for the maximally exposed individual (MEI) was about 1500- and 40-fold below the EPA reference dose (RfD) for Cr(III) and Cr(VI), respectively. It was shown that for residential sites, the most important route of exposure to Cr(III) was incidental soil ingestion. Although not relevant to these sites specifically, if garden vegetables could be successfully grown in these soils, then they would probably be the predominant source of uptake of Cr(III). Since inhalation of Cr(VI)-contaminated dust (but not ingestion or dermal contact) poses a cancer hazard, the doses and associated risks were assessed. The estimated cancer risks for the MEI and most likely exposed individual (MLEI) were approximately 5 x 10(-9) and 2 x 10(-9), respectively. These levels of risk have always been considered well below those that warrant regulatory concern. For persons living on residential properties, the cancer risk due to inhaling suspended particles is likely to be less than 1 in 1,000,000 if Cr(VI) levels in soil are less than 180 mg/kg (ppm). Based on this analysis, the levels of Cr(III) and Cr(VI) at this and similar sites do not pose a health hazard following acute or chronic exposure.","Assessment of the human health risks posed by exposure to chromium-contaminated soils Abs: Millions of tons of chromite-ore processing residue have been used as fill in various locations in northern New Jersey and elsewhere in the United States. The primary toxicants in the residue are trivalent chromium [Cr(III)] and hexavalent chromium [Cr(VI)]. The hazard posed by Cr(III) is negligible due to its low acute and chronic toxicity. In contrast, Cr(VI) is a human carcinogen following inhalation of high concentrations. It can also cause allergic contact dermatitis. This evaluation addresses a residential site where the arithmetic mean (x) and geometric mean (gm) concentrations of Cr(III) in soil were 2879 and 1212 mg/kg (ppm). The mean and geometric mean concentrations of Cr(VI) were 180 and 4 mg/kg, respectively. The uptake (absorbed dose) of Cr(III) via soil ingestion, consumption of homegrown vegetables, and ingestion of inspired particles was determined. The uptake of Cr(VI) via dermal absorption from contact with surface soil and building wall surfaces, as well as inhalation, was also evaluated. The techniques used in this assessment are applicable for evaluating the human health risks posed by any residential site having contaminated soil. The potential for both sensitized and unsensitized persons to develop allergic contact dermatitis due to exposure to soil contaminated at these levels was found to be negligible. The estimated average daily dose (ADD) via ingestion and dermal absorption for the maximally exposed individual (MEI) was about 1500- and 40-fold below the EPA reference dose (RfD) for Cr(III) and Cr(VI), respectively. It was shown that for residential sites, the most important route of exposure to Cr(III) was incidental soil ingestion. Although not relevant to these sites specifically, if garden vegetables could be successfully grown in these soils, then they would probably be the predominant source of uptake of Cr(III). Since inhalation of Cr(VI)-contaminated dust (but not ingestion or dermal contact) poses a cancer hazard, the doses and associated risks were assessed. The estimated cancer risks for the MEI and most likely exposed individual (MLEI) were approximately 5 x 10(-9) and 2 x 10(-9), respectively. These levels of risk have always been considered well below those that warrant regulatory concern. For persons living on residential properties, the cancer risk due to inhaling suspended particles is likely to be less than 1 in 1,000,000 if Cr(VI) levels in soil are less than 180 mg/kg (ppm). Based on this analysis, the levels of Cr(III) and Cr(VI) at this and similar sites do not pose a health hazard following acute or chronic exposure."
48588,Borella et al. 1990,"Cadmium, nickel, chromium and lead accumulate in human lymphocytes and interfere with PHA-induced proliferation","The in vitro effect of five toxic metals (cadmium, lead, nickel, barium, chromium III and VI) on PHA-induced blastogenesis in human lymphocytes was investigated by [3H]-thymidine incorporation. With the exception of hexavalent chromium, the metals tested were in the chloride forms. The levels of metals associated with lymphocytes were measured under our experimental procedure. An inhibitory effect was found when cadmium was added at doses which closely approximate those of occupationally exposed subjects. Hexavalent chromium and nickel showed a biphasic pattern, with a stimulatory effect at the lowest concentrations tested (10(-8)-10(-6) mol/L) and an inhibitory effect on thymidine incorporation at concentrations higher than 10(-6) and 10(-4) mol/L, respectively. No effect was observed when lead, barium, and trivalent chromium were added to the culture medium. All metals showed the ability to enter the lymphocytes or to adhere to their surface, and the interaction appeared to be quite stable, with the exception of barium. The relationship between metal accumulation and [3H]-thymidine incorporation in the cells is discussed.","Cadmium, nickel, chromium and lead accumulate in human lymphocytes and interfere with PHA-induced proliferation Abs: The in vitro effect of five toxic metals (cadmium, lead, nickel, barium, chromium III and VI) on PHA-induced blastogenesis in human lymphocytes was investigated by [3H]-thymidine incorporation. With the exception of hexavalent chromium, the metals tested were in the chloride forms. The levels of metals associated with lymphocytes were measured under our experimental procedure. An inhibitory effect was found when cadmium was added at doses which closely approximate those of occupationally exposed subjects. Hexavalent chromium and nickel showed a biphasic pattern, with a stimulatory effect at the lowest concentrations tested (10(-8)-10(-6) mol/L) and an inhibitory effect on thymidine incorporation at concentrations higher than 10(-6) and 10(-4) mol/L, respectively. No effect was observed when lead, barium, and trivalent chromium were added to the culture medium. All metals showed the ability to enter the lymphocytes or to adhere to their surface, and the interaction appeared to be quite stable, with the exception of barium. The relationship between metal accumulation and [3H]-thymidine incorporation in the cells is discussed."
48236,Denizeau and  Marion 1989,Genotoxic effects of heavy metals in rat hepatocytes,"The genotoxic interaction of metals, which are common environmental contaminants, was studied in cultured hepatocytes. Freshly isolated rat hepatocytes were exposed to concentrations of cadmium, copper, silver and lead salts ranging from non-cytotoxic to moderately cytotoxic (as determined by LDH release), and the incorporation of [3H]thymidine into the DNA, as a measure of repair synthesis, was followed. In addition, the uptake of metals by the nuclear fraction was determined using Inductively Coupled Plasma/Mass Spectrometry or atomic absorption spectrophotometry. The evaluation of binding of 109Cd to the DNA in situ was also attempted. It was observed that after a 20 h exposure period, all the metals investigated were found in the nuclear fraction of hepatocytes, with Ag apparently being accumulated less efficiently. In parallel, Cd (0.18 to 1.8 microM) and Cu (7.9 to 78.5 microM) consistently produced a statistically significant stimulation of [3H]thymidine incorporation into the DNA, in the presence or absence of hydroxyurea while Ag was active only at the highest concentration tested (18.5 microM). In contrast, Pb failed to induce a UDS response at the levels used. Moreover, exposure of hepatocytes to 1.8 microM 109CdCl2 for 20 h led to a DNA binding ratio of 0.98 +/- 0.23 ng Cd/micrograms DNA. The present results support the view that the nucleus may be an important target organelle for metal toxicity.","Genotoxic effects of heavy metals in rat hepatocytes Abs: The genotoxic interaction of metals, which are common environmental contaminants, was studied in cultured hepatocytes. Freshly isolated rat hepatocytes were exposed to concentrations of cadmium, copper, silver and lead salts ranging from non-cytotoxic to moderately cytotoxic (as determined by LDH release), and the incorporation of [3H]thymidine into the DNA, as a measure of repair synthesis, was followed. In addition, the uptake of metals by the nuclear fraction was determined using Inductively Coupled Plasma/Mass Spectrometry or atomic absorption spectrophotometry. The evaluation of binding of 109Cd to the DNA in situ was also attempted. It was observed that after a 20 h exposure period, all the metals investigated were found in the nuclear fraction of hepatocytes, with Ag apparently being accumulated less efficiently. In parallel, Cd (0.18 to 1.8 microM) and Cu (7.9 to 78.5 microM) consistently produced a statistically significant stimulation of [3H]thymidine incorporation into the DNA, in the presence or absence of hydroxyurea while Ag was active only at the highest concentration tested (18.5 microM). In contrast, Pb failed to induce a UDS response at the levels used. Moreover, exposure of hepatocytes to 1.8 microM 109CdCl2 for 20 h led to a DNA binding ratio of 0.98 +/- 0.23 ng Cd/micrograms DNA. The present results support the view that the nucleus may be an important target organelle for metal toxicity."
47677,Olin et al. 1996,The effects of some redox-active metals and reactive aldehydes on DNA-protein cross-links in vitro,"It has been suggested that the measurement of DNA-protein cross-links (DPCs) may be of value in the assessment of an individual's exposure to specific environmental insults. For a biomarker to be reliable, its results should be consistent and specific. In the present study, the precision and specificity of the K+-SDS precipitation assay as a measurement for DPCs was assessed. Chinese hamster ovary (CHO) and human fibroblast cells were exposed to a number of diverse oxidative insults, whose concentrations ranged from physiological to super-physiological levels. Only super-physiological concentrations of the insults induced the formation of DPCs. Formaldehyde, chromate, vanadate, acetaldehyde, and copper were found to be the greatest inducers of DPC formation, followed by manganese and iron. DPC induction was consistently higher in the CHO cells than in human fibroblast cells. While the K+-SDS assay may be of value as an indicator of cumulative DNA damage, its value as a biomarker for specific environmental insults may be limited.","The effects of some redox-active metals and reactive aldehydes on DNA-protein cross-links in vitro Abs: It has been suggested that the measurement of DNA-protein cross-links (DPCs) may be of value in the assessment of an individual's exposure to specific environmental insults. For a biomarker to be reliable, its results should be consistent and specific. In the present study, the precision and specificity of the K+-SDS precipitation assay as a measurement for DPCs was assessed. Chinese hamster ovary (CHO) and human fibroblast cells were exposed to a number of diverse oxidative insults, whose concentrations ranged from physiological to super-physiological levels. Only super-physiological concentrations of the insults induced the formation of DPCs. Formaldehyde, chromate, vanadate, acetaldehyde, and copper were found to be the greatest inducers of DPC formation, followed by manganese and iron. DPC induction was consistently higher in the CHO cells than in human fibroblast cells. While the K+-SDS assay may be of value as an indicator of cumulative DNA damage, its value as a biomarker for specific environmental insults may be limited."
47567,Erickson et al. 1994,"Acute bone marrow toxicity and pancytopenia following exposure to lead chromate, xylene, and ethylbenzene in a degloving injury","A case of unique acute bone marrow toxicity and pancytopenia following subcutaneous exposure to lead chromate, xylene, and ethylbenzene in a previously healthy patient is reported. The patient sustained an extensive degloving injury to his lower extremity. The wound was contaminated with traffic paint containing lead chromate pigment along with a large volume of xylene and ethylbenzene solvent. Consequences of the patient's clinical course and management of degloving injuries are discussed.","Acute bone marrow toxicity and pancytopenia following exposure to lead chromate, xylene, and ethylbenzene in a degloving injury Abs: A case of unique acute bone marrow toxicity and pancytopenia following subcutaneous exposure to lead chromate, xylene, and ethylbenzene in a previously healthy patient is reported. The patient sustained an extensive degloving injury to his lower extremity. The wound was contaminated with traffic paint containing lead chromate pigment along with a large volume of xylene and ethylbenzene solvent. Consequences of the patient's clinical course and management of degloving injuries are discussed."
47350,Lefebvre and  Pezerat 1994,Reactive oxygen species produced from chromate pigments and ascorbate,"The reactions of various chromate pigments and ascorbate were investigated by an ESR spin trapping technique. Production of Cr(V) was detected directly and productions of very electrophilic reactive oxygen species (ROS) was detected via the oxidation of formate. We demonstrated previously that both dissolved oxygen and Cr (V) were essential in the production of ROS in this system, and that ROS production was inhibited by catalase. We studied here the effect of solubility of different chromate pigments: sodium, calcium, strontium, basic zinc, basic lead supported on silica, and lead and barium chromates on the production of ROS in buffered medium and cell culture medium (Dublecco's Modified Eagle medium + fetal calf serum). Sodium, calcium, basic zinc, and basic lead chromates were active in the production of ROS in presence of cell culture medium, whereas lead and barium chromates were inactive.","Reactive oxygen species produced from chromate pigments and ascorbate Abs: The reactions of various chromate pigments and ascorbate were investigated by an ESR spin trapping technique. Production of Cr(V) was detected directly and productions of very electrophilic reactive oxygen species (ROS) was detected via the oxidation of formate. We demonstrated previously that both dissolved oxygen and Cr (V) were essential in the production of ROS in this system, and that ROS production was inhibited by catalase. We studied here the effect of solubility of different chromate pigments: sodium, calcium, strontium, basic zinc, basic lead supported on silica, and lead and barium chromates on the production of ROS in buffered medium and cell culture medium (Dublecco's Modified Eagle medium + fetal calf serum). Sodium, calcium, basic zinc, and basic lead chromates were active in the production of ROS in presence of cell culture medium, whereas lead and barium chromates were inactive."
47349,Wise et al. 1994,Cell-enhanced dissolution of carcinogenic lead chromate particles: the role of individual dissolution products in clastogenesis,"Lead chromate induces chromosomal damage as a result of extracellular dissolution producing solubilized chromium and lead and we show here that the dissolution process is greatly accelerated by the presence of cells. We have sought to determine which of these ions is involved in lead chromate-induced clastogenicity. Cell-mediated extracellular dissolution of particulate lead chromate resulted in the accumulation of both solubilized chromium and solubilized lead, reaching concentrations in the extracellular medium of 15 and 1.9 microM respectively and reaching concentrations inside the cell of 2700 and 97 microM respectively. Both the extracellular and intracellular accumulation of chromium was time dependent and both the solubilized lead and chromium increased proportionately from a lower dose to a higher dose. Exposing cells to water soluble sodium chromate under conditions which produced similar time-dependent intracellular concentrations of chromium also produced a similar amount and spectrum of chromosome damage as lead chromate. In contrast, exposure to lead glutamate resulted in intracellular lead levels 438-times higher than those produced by lead chromate, but produced no chromosome damage. A higher dose of lead glutamate was weakly clastogenic, but it induced a different spectrum of chromosomal aberrations than lead chromate. Pretreatment of cells with vitamin E had no effect on the uptake of chromium, but reduced both sodium chromate- and lead chromate-induced clastogenesis by 54-93%. Vitamin E pretreatment did not affect lead glutamate-induced clastogenesis. The results of this study indicate that although lead(II) is weakly clastogenic at high doses, hexavalent chromium is the proximate clastogen in lead chromate-induced clastogenesis. Additionally, this is the first report that pretreatment of cells with vitamin E can block clastogenesis induced by particulate chromates.","Cell-enhanced dissolution of carcinogenic lead chromate particles: the role of individual dissolution products in clastogenesis Abs: Lead chromate induces chromosomal damage as a result of extracellular dissolution producing solubilized chromium and lead and we show here that the dissolution process is greatly accelerated by the presence of cells. We have sought to determine which of these ions is involved in lead chromate-induced clastogenicity. Cell-mediated extracellular dissolution of particulate lead chromate resulted in the accumulation of both solubilized chromium and solubilized lead, reaching concentrations in the extracellular medium of 15 and 1.9 microM respectively and reaching concentrations inside the cell of 2700 and 97 microM respectively. Both the extracellular and intracellular accumulation of chromium was time dependent and both the solubilized lead and chromium increased proportionately from a lower dose to a higher dose. Exposing cells to water soluble sodium chromate under conditions which produced similar time-dependent intracellular concentrations of chromium also produced a similar amount and spectrum of chromosome damage as lead chromate. In contrast, exposure to lead glutamate resulted in intracellular lead levels 438-times higher than those produced by lead chromate, but produced no chromosome damage. A higher dose of lead glutamate was weakly clastogenic, but it induced a different spectrum of chromosomal aberrations than lead chromate. Pretreatment of cells with vitamin E had no effect on the uptake of chromium, but reduced both sodium chromate- and lead chromate-induced clastogenesis by 54-93%. Vitamin E pretreatment did not affect lead glutamate-induced clastogenesis. The results of this study indicate that although lead(II) is weakly clastogenic at high doses, hexavalent chromium is the proximate clastogen in lead chromate-induced clastogenesis. Additionally, this is the first report that pretreatment of cells with vitamin E can block clastogenesis induced by particulate chromates."
47161,Manning et al. 1994,"Induction of internucleosomal DNA fragmentation by carcinogenic chromate: relationship to DNA damage, genotoxicity, and inhibition of macromolecular synthesis","Hexavalent chromium (Cr) compounds are respiratory carcinogens in humans and animals. Treatment of Chinese hamster ovary cells with 150 and 300 microM sodium chromate (Na2CrO4) for 2 hr decreased colony-forming efficiency by 46 and 92%, respectively. These treatments induced dose-dependent internucleosomal fragmentation of cellular DNA beyond 24 hr after chromate treatment. This fragmentation pattern is characteristic of apoptosis as a mechanism of cell death. These treatments also induced an immediate inhibition of macromolecular synthesis and delayed progression of cells through S-phase of the cell cycle. Cell growth (as evidenced by DNA synthesis) was inhibited for at least 4 days and transcription remained suppressed for at least 32 hr. Many of the cells that did progress to metaphase exhibited chromosome damage. Chromate caused the dose-dependent formation of DNA single-strand breaks and DNA-protein cross-links, but these were repaired 8 and 24 hr after removal of the treatment, respectively. In contrast, Cr-DNA adducts (up to 1/100 base-pairs) were extremely resistant to repair and were still detectable even 5 days after treatment. Compared with other regions of the genome, DNA-protein cross-links and Cr adducts were preferentially associated with the nuclear matrix DNA of treated cells, which was 4.5-fold enriched in actively transcribed genes. Chromium adducts, formed on DNA in vitro at a similar level to that detected in nuclear matrix DNA, arrested the progression of a DNA polymerase in a sequence-specific manner, possibly through the formation of DNA-DNA cross-links.(ABSTRACT TRUNCATED AT 250 WORDS)","Induction of internucleosomal DNA fragmentation by carcinogenic chromate: relationship to DNA damage, genotoxicity, and inhibition of macromolecular synthesis Abs: Hexavalent chromium (Cr) compounds are respiratory carcinogens in humans and animals. Treatment of Chinese hamster ovary cells with 150 and 300 microM sodium chromate (Na2CrO4) for 2 hr decreased colony-forming efficiency by 46 and 92%, respectively. These treatments induced dose-dependent internucleosomal fragmentation of cellular DNA beyond 24 hr after chromate treatment. This fragmentation pattern is characteristic of apoptosis as a mechanism of cell death. These treatments also induced an immediate inhibition of macromolecular synthesis and delayed progression of cells through S-phase of the cell cycle. Cell growth (as evidenced by DNA synthesis) was inhibited for at least 4 days and transcription remained suppressed for at least 32 hr. Many of the cells that did progress to metaphase exhibited chromosome damage. Chromate caused the dose-dependent formation of DNA single-strand breaks and DNA-protein cross-links, but these were repaired 8 and 24 hr after removal of the treatment, respectively. In contrast, Cr-DNA adducts (up to 1/100 base-pairs) were extremely resistant to repair and were still detectable even 5 days after treatment. Compared with other regions of the genome, DNA-protein cross-links and Cr adducts were preferentially associated with the nuclear matrix DNA of treated cells, which was 4.5-fold enriched in actively transcribed genes. Chromium adducts, formed on DNA in vitro at a similar level to that detected in nuclear matrix DNA, arrested the progression of a DNA polymerase in a sequence-specific manner, possibly through the formation of DNA-DNA cross-links.(ABSTRACT TRUNCATED AT 250 WORDS)"
47099,Spear et al. 1998,Chemical speciation of lead dust associated with primary lead smelting,"#The research presented in this article assessed geochemical factors relating to dust produced during primary lead smelting. Bulk dust samples and size-selective airborne dust samples were collected from four areas of a primary lead smelter and analyzed by X-ray diffraction and sequential chemical extraction. X-ray diffraction showed that the smelter dusts were composed primarily of sulfides, oxides, sulfates, and silicates of metal ores, with galena being the primary dust component. Sequential extraction revealed the solubility of lead compounds at less than 7% in the exchangeable and mildly acidic steps for the bulk dusts collected from four smelter areas. The later steps of the extraction procedure were more effective in dissolving the lead compounds associated with the bulk dust samples, with 43%, 26%, and 8% of the total lead, in the ore storage, sinter, and blast/dross smelter areas, respectively, being extracted in the residual step. Sequential extraction of coarse airborne dust samples from the ore storage and sinter plant showed that 1.2% and 4.1% of the total lead, respectively, was exchangeable. The finer particle size fractions from these areas of the smelter showed higher percentages of exchangeable lead. Of the course airborne dust from the blast/dross furnace processes, 65% of the total lead was exchangeable. However, the largest percentage of lead from these areas was associated with the finer particle-size fractions. If lead bioavailability is related to its solubility as determined through sequential extraction, the health hazards associated with lead exposure may be appreciably enhanced in the blast and dross furnace processes.","Chemical speciation of lead dust associated with primary lead smelting Abs: #The research presented in this article assessed geochemical factors relating to dust produced during primary lead smelting. Bulk dust samples and size-selective airborne dust samples were collected from four areas of a primary lead smelter and analyzed by X-ray diffraction and sequential chemical extraction. X-ray diffraction showed that the smelter dusts were composed primarily of sulfides, oxides, sulfates, and silicates of metal ores, with galena being the primary dust component. Sequential extraction revealed the solubility of lead compounds at less than 7% in the exchangeable and mildly acidic steps for the bulk dusts collected from four smelter areas. The later steps of the extraction procedure were more effective in dissolving the lead compounds associated with the bulk dust samples, with 43%, 26%, and 8% of the total lead, in the ore storage, sinter, and blast/dross smelter areas, respectively, being extracted in the residual step. Sequential extraction of coarse airborne dust samples from the ore storage and sinter plant showed that 1.2% and 4.1% of the total lead, respectively, was exchangeable. The finer particle size fractions from these areas of the smelter showed higher percentages of exchangeable lead. Of the course airborne dust from the blast/dross furnace processes, 65% of the total lead was exchangeable. However, the largest percentage of lead from these areas was associated with the finer particle-size fractions. If lead bioavailability is related to its solubility as determined through sequential extraction, the health hazards associated with lead exposure may be appreciably enhanced in the blast and dross furnace processes."
43581,Landolph 1989,"Molecular and cellular mechanisms of transformation of C3H/10T1/2 Cl 8 and diploid human fibroblasts by unique carcinogenic, nonmutagenic metal compounds: a review","Work from our laboratory showed that carcinogenic metal salts of arsenic, nickel, and chromium induced morphological transformation of cultured C3H/10T1/2 Cl 8 (10T1/2) mouse embryo cells, and that many of the transformants grow in soft agarose and form tumors in nude mice. Concentrations of arsenic, nickel, and chromium compounds that induced morphological transformation did not induce mutation to ouabain resistance in 10T1/2 cells. This indicated that the mechanism of metal induced morphological transformation was likely not caused by induction of base substitution mutations, and in the case of lead chromate, likely not caused by frameshift or deletion mutations. In addition, we showed that carcinogenic arsenic, nickel, and chromium compounds, and MNNG, induced anchorage independence in diploid human fibroblasts. Anchorage-independent cell strains derived from anchorage-independent colonies were stable but did not form foci and eventually senesced, therefore, arsenic and nickel compounds and lead chromate induced stable anchorage independence as an isolated phenotype. Nickel compounds and lead chromate induced anchorage independence but not mutation to ouabain resistance or to 6-thioguanine resistance. Hence, the mechanism of induction of anchorage independence by these metal salts in human fibroblasts was likely not via induction of base substitution, frameshift, or deletion mutations that would be measured in these mutation assays.(ABSTRACT TRUNCATED AT 250 WORDS)","Molecular and cellular mechanisms of transformation of C3H/10T1/2 Cl 8 and diploid human fibroblasts by unique carcinogenic, nonmutagenic metal compounds: a review Abs: Work from our laboratory showed that carcinogenic metal salts of arsenic, nickel, and chromium induced morphological transformation of cultured C3H/10T1/2 Cl 8 (10T1/2) mouse embryo cells, and that many of the transformants grow in soft agarose and form tumors in nude mice. Concentrations of arsenic, nickel, and chromium compounds that induced morphological transformation did not induce mutation to ouabain resistance in 10T1/2 cells. This indicated that the mechanism of metal induced morphological transformation was likely not caused by induction of base substitution mutations, and in the case of lead chromate, likely not caused by frameshift or deletion mutations. In addition, we showed that carcinogenic arsenic, nickel, and chromium compounds, and MNNG, induced anchorage independence in diploid human fibroblasts. Anchorage-independent cell strains derived from anchorage-independent colonies were stable but did not form foci and eventually senesced, therefore, arsenic and nickel compounds and lead chromate induced stable anchorage independence as an isolated phenotype. Nickel compounds and lead chromate induced anchorage independence but not mutation to ouabain resistance or to 6-thioguanine resistance. Hence, the mechanism of induction of anchorage independence by these metal salts in human fibroblasts was likely not via induction of base substitution, frameshift, or deletion mutations that would be measured in these mutation assays.(ABSTRACT TRUNCATED AT 250 WORDS)"
41891,Nettesheim et al. 1970,Effect of chronic exposure to air pollutants on the respiratory tracts of mice: Histopathological findings,"The effect of chronic exposure to air pollutants was studied in mice. C57BL/6-mice were exposed to filtered air, chromium-trioxide (1333820) (CT) dust, or artificial smog for 5.5 hours per day, 5 days per week, for up to 160 weeks. Some animals were irradiated with 100 roentgens of whole body X-radiation or were infected with an influenza virus 4 or 2 weeks prior to exposure, respectively. The artificial smog consisted of a mixture of straight run unleaded gasoline and oxygen and ozone, the maximum concentrations being 24 to 30 and 1 part per million, respectively. All animals were necropsied and their lungs were examined for histopathological changes. The mean survival time was 102.4 weeks and was not significantly affected by the type of exposure. Males had a slightly higher incidence of tumors than females. Irradiation with X-rays increased the incidence of lung tumors in females but not in males. Chronic exposure to artificial smog increased the lung tumor incidence in both sexes. Infection with influenza virus reduced lung tumor incidence. Exposure to CT dust had no effect on lung tumor incidence. All lung tumors were adenomas or adenocarcinomas. No additive or potentiating effects were observed. Nonneoplastic changes included epithelial hyperplasia and disorganization at the bronchiolar/alveolar junctions caused by the artificial smog and goblet cell metaplasia in the small airways after introduction of virus infection. Infection with the virus increased the retention of CT. X-radiation did not cause any detectable cellular changes.","Effect of chronic exposure to air pollutants on the respiratory tracts of mice: Histopathological findings Abs: The effect of chronic exposure to air pollutants was studied in mice. C57BL/6-mice were exposed to filtered air, chromium-trioxide (1333820) (CT) dust, or artificial smog for 5.5 hours per day, 5 days per week, for up to 160 weeks. Some animals were irradiated with 100 roentgens of whole body X-radiation or were infected with an influenza virus 4 or 2 weeks prior to exposure, respectively. The artificial smog consisted of a mixture of straight run unleaded gasoline and oxygen and ozone, the maximum concentrations being 24 to 30 and 1 part per million, respectively. All animals were necropsied and their lungs were examined for histopathological changes. The mean survival time was 102.4 weeks and was not significantly affected by the type of exposure. Males had a slightly higher incidence of tumors than females. Irradiation with X-rays increased the incidence of lung tumors in females but not in males. Chronic exposure to artificial smog increased the lung tumor incidence in both sexes. Infection with influenza virus reduced lung tumor incidence. Exposure to CT dust had no effect on lung tumor incidence. All lung tumors were adenomas or adenocarcinomas. No additive or potentiating effects were observed. Nonneoplastic changes included epithelial hyperplasia and disorganization at the bronchiolar/alveolar junctions caused by the artificial smog and goblet cell metaplasia in the small airways after introduction of virus infection. Infection with the virus increased the retention of CT. X-radiation did not cause any detectable cellular changes."
41073,Levaggi et al. 1974,Quantitative analysis of nitric oxide in presence of nitrogen dioxide at atmospheric concentrations,"Chromium trioxide (Cr03) was tested as a replacement for the potassium permanganate-sulfuric acid solutions designed to oxidize NO for conversion and detection as NO2. The Cr03 oxidizer was prepared by soaking firebrick in a 17% solution of pure Cr03, draining, and drying at 105 degrees C. The final loading was about 10% by weight. Since the optimal relative humidity (R.H.) working range of the Cr03 oxidizer without sulfuric acid is higher (35-90% R.H.) than the material mixed with sulfuric acid, a humidifier with a shortened inlet tube was used so that the airstream was blown over water rather than bubbled through it. This gave a relative humidity of about 70-80%. Three to 5 grams of the hydrated oxidizer was placed in a midget impinger. An interesting and desirable feature of the Cr03 oxidizer is its color change when hydrated (dull yellow) or dehydrated (dull pink) and when its oxidizing ability is spent (greenish brown). The midget impinger should be changed before more than half has depleted. At ambient levels of NO the oxidant should last at least 3 months. The oxidation efficiency is close to 100%.","Quantitative analysis of nitric oxide in presence of nitrogen dioxide at atmospheric concentrations Abs: Chromium trioxide (Cr03) was tested as a replacement for the potassium permanganate-sulfuric acid solutions designed to oxidize NO for conversion and detection as NO2. The Cr03 oxidizer was prepared by soaking firebrick in a 17% solution of pure Cr03, draining, and drying at 105 degrees C. The final loading was about 10% by weight. Since the optimal relative humidity (R.H.) working range of the Cr03 oxidizer without sulfuric acid is higher (35-90% R.H.) than the material mixed with sulfuric acid, a humidifier with a shortened inlet tube was used so that the airstream was blown over water rather than bubbled through it. This gave a relative humidity of about 70-80%. Three to 5 grams of the hydrated oxidizer was placed in a midget impinger. An interesting and desirable feature of the Cr03 oxidizer is its color change when hydrated (dull yellow) or dehydrated (dull pink) and when its oxidizing ability is spent (greenish brown). The midget impinger should be changed before more than half has depleted. At ambient levels of NO the oxidant should last at least 3 months. The oxidation efficiency is close to 100%."
40467,Haber and  Maier 2002,Scientific criteria used for the development of occupational exposure limits for metals and other mining-related chemicals,"The scientific approaches employed by selected internationally recognized organizations in developing occupational exposure limits (OELs) for metals and other mining-related chemicals were surveyed, and differences and commonalties were identified. The analysis identified an overriding need to increase transparency in current OEL documentation. OEL documentation should adhere to good risk characterization principles and should identify (1) the methodology used and scientific judgments made; (2) the data used as the basis for the OEL calculation; and (3) the uncertainties and overall confidence in the OEL derivation. At least within a single organization, a consistent approach should be used to derive OELs. Opportunities for harmonization of scientific criteria were noted, including (1) consideration of severity in identification of the point of departure; (2) definition of the minimum data set; (3) approaches for interspecies extrapolation; (4) identification of default uncertainty factors for developing OELs; and (5) approaches for consideration of speciation and essentiality of metals. Potential research approaches to provide the fundamental data needed to address each individual scientific criterion are described. Increased harmonization of scientific criteria will ultimately lead to OEL derivation approaches rooted in the best science and will facilitate greater pooling of resources among organizations that establish OELs and improved protection of worker health.","Scientific criteria used for the development of occupational exposure limits for metals and other mining-related chemicals Abs: The scientific approaches employed by selected internationally recognized organizations in developing occupational exposure limits (OELs) for metals and other mining-related chemicals were surveyed, and differences and commonalties were identified. The analysis identified an overriding need to increase transparency in current OEL documentation. OEL documentation should adhere to good risk characterization principles and should identify (1) the methodology used and scientific judgments made; (2) the data used as the basis for the OEL calculation; and (3) the uncertainties and overall confidence in the OEL derivation. At least within a single organization, a consistent approach should be used to derive OELs. Opportunities for harmonization of scientific criteria were noted, including (1) consideration of severity in identification of the point of departure; (2) definition of the minimum data set; (3) approaches for interspecies extrapolation; (4) identification of default uncertainty factors for developing OELs; and (5) approaches for consideration of speciation and essentiality of metals. Potential research approaches to provide the fundamental data needed to address each individual scientific criterion are described. Increased harmonization of scientific criteria will ultimately lead to OEL derivation approaches rooted in the best science and will facilitate greater pooling of resources among organizations that establish OELs and improved protection of worker health."
38198,Landolph 1994,Molecular mechanisms of transformation of C3H/10T1/2 C1 8 mouse embryo cells and diploid human fibroblasts by carcinogenic metal compounds,"Carcinogenic arsenic, nickel, and chromium compounds induced morphological and neoplastic transformation but no mutation to ouabain resistance in 10T1/2 mouse embryo cells; lead chromate also did not induce mutation to ouabain or 6-thioguanine resistance in Chinese hamster ovary cells. The mechanism of metal-induced morphological transformation was likely not due to the specific base substitution mutations measured in ouabain resistance mutation assays, and for lead chromate, likely not due to this type of base substitution mutation or to frameshift mutations. Preliminary data indicate increases in steady-state levels of c-myc RNA in arsenic-, nickel-, and chromium-transformed cell lines. We also showed that carcinogenic nickel, chromium, and arsenic compounds and N-methyl-N-nitro-N-nitrosoguanidine (MNNG) induced stable anchorage independence (Al) in diploid human fibroblasts (DHF) but no focus formation or immortality. Nickel subsulfide and lead chromate induced Al but not mutation to 6-thioguanine resistance. The mechanism of induction of Al by metal salts in DHF was likely not by the type of base substitution or frameshift mutations measured in these assays. MNNG induced Al, mutation to 6-thioguanine resistance, and mutation to ouabain resistance, and might induce Al by base substitution or frameshift mutations. Dexamethasone, aspirin, and salicylic acid inhibited nickel subsulfide, MNNG, and 12-O-tetrade-canoylphorbol-13-acetate (TPA)-induced Al in DHF, suggesting that arachidonic acid metabolism and oxygen radical generation play a role in induction of Al. We propose that nickel compounds stimulate arachidonic acid metabolism, consequent oxygen radical generation, and oxygen radical attack upon DNA.(ABSTRACT TRUNCATED AT 250 WORDS)","Molecular mechanisms of transformation of C3H/10T1/2 C1 8 mouse embryo cells and diploid human fibroblasts by carcinogenic metal compounds Abs: Carcinogenic arsenic, nickel, and chromium compounds induced morphological and neoplastic transformation but no mutation to ouabain resistance in 10T1/2 mouse embryo cells; lead chromate also did not induce mutation to ouabain or 6-thioguanine resistance in Chinese hamster ovary cells. The mechanism of metal-induced morphological transformation was likely not due to the specific base substitution mutations measured in ouabain resistance mutation assays, and for lead chromate, likely not due to this type of base substitution mutation or to frameshift mutations. Preliminary data indicate increases in steady-state levels of c-myc RNA in arsenic-, nickel-, and chromium-transformed cell lines. We also showed that carcinogenic nickel, chromium, and arsenic compounds and N-methyl-N-nitro-N-nitrosoguanidine (MNNG) induced stable anchorage independence (Al) in diploid human fibroblasts (DHF) but no focus formation or immortality. Nickel subsulfide and lead chromate induced Al but not mutation to 6-thioguanine resistance. The mechanism of induction of Al by metal salts in DHF was likely not by the type of base substitution or frameshift mutations measured in these assays. MNNG induced Al, mutation to 6-thioguanine resistance, and mutation to ouabain resistance, and might induce Al by base substitution or frameshift mutations. Dexamethasone, aspirin, and salicylic acid inhibited nickel subsulfide, MNNG, and 12-O-tetrade-canoylphorbol-13-acetate (TPA)-induced Al in DHF, suggesting that arachidonic acid metabolism and oxygen radical generation play a role in induction of Al. We propose that nickel compounds stimulate arachidonic acid metabolism, consequent oxygen radical generation, and oxygen radical attack upon DNA.(ABSTRACT TRUNCATED AT 250 WORDS)"
37333,Lioy et al. 2002,Dust: a metric for use in residential and building exposure assessment and source characterization,"In this review, we examine house dust and residential soil and their use for identifying sources and the quantifying levels of toxicants for the estimation of exposure. We answer critical questions that focus on the selection of samples or sampling strategies for collection and discuss areas of uncertainty and gaps in knowledge. We discuss the evolution of dust sampling with a special emphasis on work conducted after the publication of the 1992 review by McArthur [Appl Occup Environ Hyg 7(9):599-606 (1992)]. The approaches to sampling dust examined include surface wipe sampling, vacuum sampling, and other sampling approaches, including attic sampling. The metrics of presentation of results for toxicants in dust surface loading (micrograms per square centimeter) or surface concentration (micrograms per gram) are discussed. We evaluate these metrics in terms of how the information can be used in source characterization and in exposure characterization. We discuss the types of companion information on source use and household or personal activity patterns required to assess the significance of the dust exposure. The status and needs for wipe samplers, surface samplers, and vacuum samplers are summarized with some discussion on the strengths and weaknesses of each type of sampler. We also discuss needs for research and development and the current status of standardization. Case studies are provided to illustrate the use of house dust and residential soil in source characterization, forensic analyses, or human exposure assessment. Key words: chemical composition, exposure characterization, house dust, physical composition, residence wipe sampling, source identification, vacuum sampling.","Dust: a metric for use in residential and building exposure assessment and source characterization Abs: In this review, we examine house dust and residential soil and their use for identifying sources and the quantifying levels of toxicants for the estimation of exposure. We answer critical questions that focus on the selection of samples or sampling strategies for collection and discuss areas of uncertainty and gaps in knowledge. We discuss the evolution of dust sampling with a special emphasis on work conducted after the publication of the 1992 review by McArthur [Appl Occup Environ Hyg 7(9):599-606 (1992)]. The approaches to sampling dust examined include surface wipe sampling, vacuum sampling, and other sampling approaches, including attic sampling. The metrics of presentation of results for toxicants in dust surface loading (micrograms per square centimeter) or surface concentration (micrograms per gram) are discussed. We evaluate these metrics in terms of how the information can be used in source characterization and in exposure characterization. We discuss the types of companion information on source use and household or personal activity patterns required to assess the significance of the dust exposure. The status and needs for wipe samplers, surface samplers, and vacuum samplers are summarized with some discussion on the strengths and weaknesses of each type of sampler. We also discuss needs for research and development and the current status of standardization. Case studies are provided to illustrate the use of house dust and residential soil in source characterization, forensic analyses, or human exposure assessment. Key words: chemical composition, exposure characterization, house dust, physical composition, residence wipe sampling, source identification, vacuum sampling."
34857,Apostoli et al. 1998,"Multiple exposure to arsenic, antimony, and other elements in art glass manufacturing","Art glass manufacturing is one of the most interesting examples of exposure to complex mixtures. Among the raw materials used are silica sand, borax, carbonates, nitrates of Ca, Na, K, and a great number of compounds that are mainly oxides of As, Sb, Al, Zn, Cr, Ni, Sn, Se, Cd, Mn, Cu, Co, Fe, Nd, Er, Eu, and La. In six art glass factories that use As or Sb as fining agents, the exposure to these elements was investigated in 32 workers by means of environmental and biological monitoring. Analysis was conducted by atomic absorption spectrometry (AAS) and inductively coupled plasma mass spectrometry (ICP-MS). The results confirmed that As, which is the main carcinogen in glass production, reaches high air concentrations and is generally above the American Conference of Governmental Industrial Hygienists (ACGIH) threshold limit value-time-weighted average (TLV-TWA) of 10 micrograms/m3. When partly substituted by antimonial compounds, As air concentrations dropped dramatically, while the air levels of Sb (which is considered less toxic but is classified as a class 2B carcinogen by IARC) were relatively low and below the ACGIH TLV-TWA of 500 micrograms/m3. Exposure to As and Sb also differed in the three types of jobs investigated: As was high in oven chargers, Sb was higher in batch mixers, and both elements were low in makers-formers. Eleven to 18 elements were detected: arsenic, Al, Ba, Sb, Pb, and Zn were the elements most frequently measured (in tens, and in some cases hundreds, of micrograms/m3), followed by B, Li, Mn, Se, Sn, Sr, Ce, La, and Nd (in micrograms or in some cases tens of micrograms/m3. The results of biological monitoring for As, Sb, and other elements were in agreement with environmental monitoring data. We concluded that multiple detection of elements is a useful tool (or the evaluation of exposure to complex mixtures such as those used in the art glass industry and that such detection also allows a more accurate evaluation of related epidemiological data.","Multiple exposure to arsenic, antimony, and other elements in art glass manufacturing Abs: Art glass manufacturing is one of the most interesting examples of exposure to complex mixtures. Among the raw materials used are silica sand, borax, carbonates, nitrates of Ca, Na, K, and a great number of compounds that are mainly oxides of As, Sb, Al, Zn, Cr, Ni, Sn, Se, Cd, Mn, Cu, Co, Fe, Nd, Er, Eu, and La. In six art glass factories that use As or Sb as fining agents, the exposure to these elements was investigated in 32 workers by means of environmental and biological monitoring. Analysis was conducted by atomic absorption spectrometry (AAS) and inductively coupled plasma mass spectrometry (ICP-MS). The results confirmed that As, which is the main carcinogen in glass production, reaches high air concentrations and is generally above the American Conference of Governmental Industrial Hygienists (ACGIH) threshold limit value-time-weighted average (TLV-TWA) of 10 micrograms/m3. When partly substituted by antimonial compounds, As air concentrations dropped dramatically, while the air levels of Sb (which is considered less toxic but is classified as a class 2B carcinogen by IARC) were relatively low and below the ACGIH TLV-TWA of 500 micrograms/m3. Exposure to As and Sb also differed in the three types of jobs investigated: As was high in oven chargers, Sb was higher in batch mixers, and both elements were low in makers-formers. Eleven to 18 elements were detected: arsenic, Al, Ba, Sb, Pb, and Zn were the elements most frequently measured (in tens, and in some cases hundreds, of micrograms/m3), followed by B, Li, Mn, Se, Sn, Sr, Ce, La, and Nd (in micrograms or in some cases tens of micrograms/m3. The results of biological monitoring for As, Sb, and other elements were in agreement with environmental monitoring data. We concluded that multiple detection of elements is a useful tool (or the evaluation of exposure to complex mixtures such as those used in the art glass industry and that such detection also allows a more accurate evaluation of related epidemiological data."
34662,Palmes and  Tomczyk 1979,Personal sampler for NOx,"A personal sampler system for NOx (NO + NO2) and NO2 has been developed for monitoring workplace air. The NO2 sampler previously reported from this laboratory uses triethanolamine to trap NO2 which diffuses through a tube of appropriate dimensions. The NOx sampler contains the same elements as the NO2 device, but it is also fitted with a chromic acid impregnated disc; this disc converts NO to NO2 which is then trapped by the triethanolamine along with preformed NO2. The trapped NO2 in all cases is determined as nitrite colorimetrically and NO is measured by difference between the NOx and NO2 values. The NOx sampler gives accurate and reproducible results if the chromic acid disc is in place for 24 hours or less; it is necessary, therefore, to insert and remove the disc within reasonably short times before and after sampling. We believe, however, that this operation will not be a serious problem for the user.","Personal sampler for NOx Abs: A personal sampler system for NOx (NO + NO2) and NO2 has been developed for monitoring workplace air. The NO2 sampler previously reported from this laboratory uses triethanolamine to trap NO2 which diffuses through a tube of appropriate dimensions. The NOx sampler contains the same elements as the NO2 device, but it is also fitted with a chromic acid impregnated disc; this disc converts NO to NO2 which is then trapped by the triethanolamine along with preformed NO2. The trapped NO2 in all cases is determined as nitrite colorimetrically and NO is measured by difference between the NOx and NO2 values. The NOx sampler gives accurate and reproducible results if the chromic acid disc is in place for 24 hours or less; it is necessary, therefore, to insert and remove the disc within reasonably short times before and after sampling. We believe, however, that this operation will not be a serious problem for the user."
33860,Parker and  Turk 1978,Delay in the development of the allergic response to metals following intratracheal instillation,"Intracheal intubation with the soluble metal salts potassium dichromate (K2Cr2O7) and nickel sulphate (NiSO4) causes a delay of up to 8 weeks in the development of delayed hypersensitivity to the specific agent. It is suggested that absorption of sensitizers by the respiratory route may, under certain circumstances, induce a state of specific immunological unresponsiveness, rather than necessarily lead to the development of a state of allergic sensitivity.","Delay in the development of the allergic response to metals following intratracheal instillation Abs: Intracheal intubation with the soluble metal salts potassium dichromate (K2Cr2O7) and nickel sulphate (NiSO4) causes a delay of up to 8 weeks in the development of delayed hypersensitivity to the specific agent. It is suggested that absorption of sensitizers by the respiratory route may, under certain circumstances, induce a state of specific immunological unresponsiveness, rather than necessarily lead to the development of a state of allergic sensitivity."
33641,Berghem et al. 1987,Fibronectin concentrations in lung lavage fluid after inhalation exposure to low levels of metals,BIOSIS COPYRIGHT: BIOL ABS. RRM RABBIT MACROPHAGE LYSOZYME COBALT,Fibronectin concentrations in lung lavage fluid after inhalation exposure to low levels of metals Abs: BIOSIS COPYRIGHT: BIOL ABS. RRM RABBIT MACROPHAGE LYSOZYME COBALT
33586,Sjogren 1980,A retrospective cohort study of mortality among stainless steel welders,"Hexavalent chromium particles are generated in the welding of stainless steel. These particles have manifested a mutagenic action in bacterial test systems and produced chromosome aberrations in cultured Chinese hamster cells. Welders who had welded stainless steel for more than 5 a during 1950--1965 were selected for this study. According to an earlier survey the hexavalent chromium exposure of such welders was often about 50 microgram/m3 (calculated as CrO3). The cohort was followed until December 1977. The expected number of deaths was calculated from cause-, gender-, age-, and year-specific death rates of the general population in Sweden. In the cohort, consisting of 234 welders, the observed numbers of total deaths and deaths caused by tumors were the same as the expected numbers. However, three welders had died of pulmonary tumors in comparison to the expected number of 0.68 (p = 0.03).","A retrospective cohort study of mortality among stainless steel welders Abs: Hexavalent chromium particles are generated in the welding of stainless steel. These particles have manifested a mutagenic action in bacterial test systems and produced chromosome aberrations in cultured Chinese hamster cells. Welders who had welded stainless steel for more than 5 a during 1950--1965 were selected for this study. According to an earlier survey the hexavalent chromium exposure of such welders was often about 50 microgram/m3 (calculated as CrO3). The cohort was followed until December 1977. The expected number of deaths was calculated from cause-, gender-, age-, and year-specific death rates of the general population in Sweden. In the cohort, consisting of 234 welders, the observed numbers of total deaths and deaths caused by tumors were the same as the expected numbers. However, three welders had died of pulmonary tumors in comparison to the expected number of 0.68 (p = 0.03)."
33438,Rivedal and  Sanner 1981,Metal salts as promoters of in vitro morphological transformation of hamster embryo cells initiated by benzo(a)pyrene,"#The hamster embryo cell bioassay has been used to study the effect of metal salts on morphological transformation. A synergistic enhancement of the transformation frequency was found for the combined treatment with organic carcinogens [benzo(a)pyrene, N-hydroxy-2-acetylaminofluorene, and 4-nitroquinoline 1-oxide] and nickel sulfate, cadmium acetate, or potassium chromate. Chromic chloride and zinc chloride did not induce transformation themselves, and they had no effect on the transformation frequency when tested in combination with benzo(a)pyrene. The synergistic effect between benzo(a)pyrene and nickel sulfate or cadmium acetate was also apparent when the cells were treated sequentially with the chemicals. When the cells were first exposed to benzo(a)pyrene, both nickel sulfate and cadmium acetate showed a promotion-like effect similar to that obtained with the tumor promoter 12-O-tetradecanoylphorbol-13-acetate. Moreover, when 12-O-tetradecanoylphorbol-13-acetate or benzo(a)pyrene were used as promoting agents, both nickel sulfate and cadmium acetate were able to initiate morphological transformation. The data suggest that the metal salts are more potent as promoters than they are as initiators. The present findings may be of importance in relation to carcinogenicity of metal compounds to humans.","Metal salts as promoters of in vitro morphological transformation of hamster embryo cells initiated by benzo(a)pyrene Abs: #The hamster embryo cell bioassay has been used to study the effect of metal salts on morphological transformation. A synergistic enhancement of the transformation frequency was found for the combined treatment with organic carcinogens [benzo(a)pyrene, N-hydroxy-2-acetylaminofluorene, and 4-nitroquinoline 1-oxide] and nickel sulfate, cadmium acetate, or potassium chromate. Chromic chloride and zinc chloride did not induce transformation themselves, and they had no effect on the transformation frequency when tested in combination with benzo(a)pyrene. The synergistic effect between benzo(a)pyrene and nickel sulfate or cadmium acetate was also apparent when the cells were treated sequentially with the chemicals. When the cells were first exposed to benzo(a)pyrene, both nickel sulfate and cadmium acetate showed a promotion-like effect similar to that obtained with the tumor promoter 12-O-tetradecanoylphorbol-13-acetate. Moreover, when 12-O-tetradecanoylphorbol-13-acetate or benzo(a)pyrene were used as promoting agents, both nickel sulfate and cadmium acetate were able to initiate morphological transformation. The data suggest that the metal salts are more potent as promoters than they are as initiators. The present findings may be of importance in relation to carcinogenicity of metal compounds to humans."
33376,Turk and  Parker 1977,"Sensitization with Cr, Ni, and Zr salts and allergic type granuloma formation in the guinea pig","Guinea pigs were sensitized to potassium dichromate, nickel sulfate and sodium zirconium lactate by three methods of immunization in Freund's complete adjuvant: Polak, split adjuvant, and maximization (modified Magnusson and Kligman). These were followed after 2 weeks by weekly intradermal injections of 25 microng of the metal salt. Delayed hypersensitivity-like reactions developed 3 to 12 weeks after initial injection. Reactivity, although strong with an increase in thickness of over 0.7 mm and/or diameter of erythema of over 8 X 8 mm, was frequently transient, the animal losing reactivity on subsequent skin test or after 2 or 3 skin tests. In two-thirds of the experiments using sodium zirconium lactate, delayed hypersensitivity-like reactions at 24 hr developed into nodular lesions which reached peak intensity at 8 days and histologically contained histiocytes with an epithelioid cell appearance and giant cells. In some experiments, sodium zirconium lactate-sensitive animals showed cross reactivity with potassium dichromate, but not with nickel sulfate.","Sensitization with Cr, Ni, and Zr salts and allergic type granuloma formation in the guinea pig Abs: Guinea pigs were sensitized to potassium dichromate, nickel sulfate and sodium zirconium lactate by three methods of immunization in Freund's complete adjuvant: Polak, split adjuvant, and maximization (modified Magnusson and Kligman). These were followed after 2 weeks by weekly intradermal injections of 25 microng of the metal salt. Delayed hypersensitivity-like reactions developed 3 to 12 weeks after initial injection. Reactivity, although strong with an increase in thickness of over 0.7 mm and/or diameter of erythema of over 8 X 8 mm, was frequently transient, the animal losing reactivity on subsequent skin test or after 2 or 3 skin tests. In two-thirds of the experiments using sodium zirconium lactate, delayed hypersensitivity-like reactions at 24 hr developed into nodular lesions which reached peak intensity at 8 days and histologically contained histiocytes with an epithelioid cell appearance and giant cells. In some experiments, sodium zirconium lactate-sensitive animals showed cross reactivity with potassium dichromate, but not with nickel sulfate."
33288,Figoni and  Treagan 1975,Inhibitory effect of nickel and chromium upon antibody response of rats to immunization with T-1 phage,Nickel and chromium significantly depressed the circulating antibody response of rats immunized with a viral antigen (T-1 phage). Consistent suppression of antibody was observed in all metal-treated animals; the greatest decrease in antibody titers was noted in animals receiving metals two weeks prior to the initial antigen dose.,Inhibitory effect of nickel and chromium upon antibody response of rats to immunization with T-1 phage Abs: Nickel and chromium significantly depressed the circulating antibody response of rats immunized with a viral antigen (T-1 phage). Consistent suppression of antibody was observed in all metal-treated animals; the greatest decrease in antibody titers was noted in animals receiving metals two weeks prior to the initial antigen dose.
31343,Pienta 1980,Transformation of Syrian hamster embryo cells by diverse chemicals and correlation with their reported carcinogenic and mutagenic activities,,Transformation of Syrian hamster embryo cells by diverse chemicals and correlation with their reported carcinogenic and mutagenic activities Abs: 
31014,Varnbo et al. 1985,Effects of toxic chemicals on the respiratory activity of cultured mouse neuroblastoma cells,"The effects of 20 common toxic chemicals on respiratory activity were investigated in mouse neuroblastoma cells. Cultured cells were grown in medium and maintained at 37 degrees-C in 5.0 percent carbon-dioxide in air. For determination of oxygen consumption, chambers were perfused with a phosphate buffered saline solution. Measurements were made polarographically with oxygen electrodes. Effects of pentachlorophenol (87865) were recorded as an initial increase followed by a gradual dose related decrease in respiration. A corresponding time course of effects was obtained for the high concentrations of hexachlorophene (70304), whereas the low concentrations caused only inhibition. Potassium-cyanide (151508), pyridine (110861), 2,5-hexanedione (110134), meta-arsenite, potassium-chromate (7789006), mercury-chloride (51312244), methylmercury (22967926), and triethyltin (997502) caused an immediate progressive dose dependent decrease in respiration. Simpler time courses of inhibition were obtained with these substances. Ethanol (64175), methanol (67561), dimethyl-sulfoxide (67685), benzidine (71432), nickel-acetate (373024), manganese-chloride (7773015), phenol (108952), cobalt-chloride (1332827), sodium-selenate (13410010), and cadmium-chloride (10108642) produced no significant changes in respiration. The authors conclude that the system presented is useful for determining toxic action of chemicals on neural respiratory activity.","Effects of toxic chemicals on the respiratory activity of cultured mouse neuroblastoma cells Abs: The effects of 20 common toxic chemicals on respiratory activity were investigated in mouse neuroblastoma cells. Cultured cells were grown in medium and maintained at 37 degrees-C in 5.0 percent carbon-dioxide in air. For determination of oxygen consumption, chambers were perfused with a phosphate buffered saline solution. Measurements were made polarographically with oxygen electrodes. Effects of pentachlorophenol (87865) were recorded as an initial increase followed by a gradual dose related decrease in respiration. A corresponding time course of effects was obtained for the high concentrations of hexachlorophene (70304), whereas the low concentrations caused only inhibition. Potassium-cyanide (151508), pyridine (110861), 2,5-hexanedione (110134), meta-arsenite, potassium-chromate (7789006), mercury-chloride (51312244), methylmercury (22967926), and triethyltin (997502) caused an immediate progressive dose dependent decrease in respiration. Simpler time courses of inhibition were obtained with these substances. Ethanol (64175), methanol (67561), dimethyl-sulfoxide (67685), benzidine (71432), nickel-acetate (373024), manganese-chloride (7773015), phenol (108952), cobalt-chloride (1332827), sodium-selenate (13410010), and cadmium-chloride (10108642) produced no significant changes in respiration. The authors conclude that the system presented is useful for determining toxic action of chemicals on neural respiratory activity."
30865,Karlsen et al. 1992,Chemical composition and morphology of welding fume particles and grinding dusts,"Elemental composition and morphology of pure manual metal arc (MMA) welding fumes, pure grinding dust, and combined fume/dust air samples were collected and determined separately under semilaboratory conditions. The base material was stainless steel. The purpose of the present study was to create a &quot;synthetic&quot; work situation under semilaboratory conditions by combining one grinding period and two MMA welding periods and comparing these results with results during welding in a workshop. The duty cycles of pure welding and of pure grinding were also observed. A comparison was also made between metal inert gas (MIG) and MMA welding on stainless steel as well as a nickel-rich alloy under regular conditions. The amount of collected material was determined by weighing the membrane filters before and after exposure, and the element contents were determined by atomic spectroscopy. Other transmission electron microscopy (TEM) filters were used for TEM and computer-image analysis, in which the amount of collected material and its morphological characteristics were observed. The arcing time and the consumption of filler material were estimated for different kinds of electrodes. Chemical analysis showed that the contents of manganese and total chromium were lower in grinding dust than in welding fumes. The contents of hexavalent chromium, Cr(VI), in grinding dust were undetectable. Samples collected in welding shops where concomitant grinding was performed contained about 30% less Cr(VI) than those collected under laboratory conditions during welding only. The sizes and shapes of the particles depend on the welding process and distance of collection from the plume of the fume. To compare laboratory experiments with regular welding situations, the experiment must resemble industrial welding.(ABSTRACT TRUNCATED AT 250 WORDS)","Chemical composition and morphology of welding fume particles and grinding dusts Abs: Elemental composition and morphology of pure manual metal arc (MMA) welding fumes, pure grinding dust, and combined fume/dust air samples were collected and determined separately under semilaboratory conditions. The base material was stainless steel. The purpose of the present study was to create a &quot;synthetic&quot; work situation under semilaboratory conditions by combining one grinding period and two MMA welding periods and comparing these results with results during welding in a workshop. The duty cycles of pure welding and of pure grinding were also observed. A comparison was also made between metal inert gas (MIG) and MMA welding on stainless steel as well as a nickel-rich alloy under regular conditions. The amount of collected material was determined by weighing the membrane filters before and after exposure, and the element contents were determined by atomic spectroscopy. Other transmission electron microscopy (TEM) filters were used for TEM and computer-image analysis, in which the amount of collected material and its morphological characteristics were observed. The arcing time and the consumption of filler material were estimated for different kinds of electrodes. Chemical analysis showed that the contents of manganese and total chromium were lower in grinding dust than in welding fumes. The contents of hexavalent chromium, Cr(VI), in grinding dust were undetectable. Samples collected in welding shops where concomitant grinding was performed contained about 30% less Cr(VI) than those collected under laboratory conditions during welding only. The sizes and shapes of the particles depend on the welding process and distance of collection from the plume of the fume. To compare laboratory experiments with regular welding situations, the experiment must resemble industrial welding.(ABSTRACT TRUNCATED AT 250 WORDS)"
29498,Chamberlain and  Tarmy 1977,Asbestos and glass fibres in bacterial mutation tests,"Asbestos fibres are carcinogenic in man and experimental animals but fine glass fibres are known, at present, only to be carcinogenic in experimental animals. Asbestos and glass fibres have been studied in mutation tests using auxotrophic strains of Escherichia coli and Salmonella typhimurium. The mutagenic activities of the positive control mutagens ultraviolet light, potassium chromate, ethyl methanesulphonate and benzo(a)pyrene were detected in the experiments. However, no mutagenic activity was found to be associted with any of the asbestos and glass fibres tested over a wide range of concentrations. The implications of these findings for the mode of action of asbestos and glass fibres as carcinogens are discussed.","Asbestos and glass fibres in bacterial mutation tests Abs: Asbestos fibres are carcinogenic in man and experimental animals but fine glass fibres are known, at present, only to be carcinogenic in experimental animals. Asbestos and glass fibres have been studied in mutation tests using auxotrophic strains of Escherichia coli and Salmonella typhimurium. The mutagenic activities of the positive control mutagens ultraviolet light, potassium chromate, ethyl methanesulphonate and benzo(a)pyrene were detected in the experiments. However, no mutagenic activity was found to be associted with any of the asbestos and glass fibres tested over a wide range of concentrations. The implications of these findings for the mode of action of asbestos and glass fibres as carcinogens are discussed."
28947,Haworth et al. 1983,Salmonella mutagenicity test results for 250 chemicals,"This publication is a presentation of Salmonella testing results on 250 coded chemicals, encompassing 370 tests. The majority of these results were previously summarized in issues of the National Toxicology Program Technical Bulletin. However, some interpretations were changed since publication in the NTP Bulletin, based upon a reevaluation of the data. The presentation here is designed both to summarize the results in the text and to present the data so that the reader has the opportunity of performing an independent evaluation of the data. The chemicals tested, their source, and purity (where known) are listed and their structures are given in Appendix 1.","Salmonella mutagenicity test results for 250 chemicals Abs: This publication is a presentation of Salmonella testing results on 250 coded chemicals, encompassing 370 tests. The majority of these results were previously summarized in issues of the National Toxicology Program Technical Bulletin. However, some interpretations were changed since publication in the NTP Bulletin, based upon a reevaluation of the data. The presentation here is designed both to summarize the results in the text and to present the data so that the reader has the opportunity of performing an independent evaluation of the data. The chemicals tested, their source, and purity (where known) are listed and their structures are given in Appendix 1."
28358,Brooks et al. 1992,Immune responses to pollutant mixtures from indoor sources,"Indoor air pollution occurs as an undesirable consequence of urbanization, energy conservation, indoor bioaerosol contamination, and use of synthetic materials and new technologies, and has become a worldwide concern. It is important to comprehend not only the diversity of pollutant hazards but also to develop novel methods and approaches that establish dose-response relationships, cause-and-effect relationships, and clinical relevance. Coincident with heightened public concern over indoor air pollution and its health consequences, a revolution in immunology has occurred. The immune system is recognized as an essential defensive and homeostatic mechanism. Unfortunately, the immune apparatus is exquisitely sensitive to toxic damage. Equally important, among the disciplines available to assess the health impact of indoor air pollutants, immunology has the capability to provide sensitive and specific tools that may accurately measure relevant clinical effects at tissue, cellular, and molecular levels. Furthermore, exciting new insights into shared communications networks between the immune, endocrine, and central nervous systems may provide future explanations for the myriad human complaints associated with indoor air pollutants.","Immune responses to pollutant mixtures from indoor sources Abs: Indoor air pollution occurs as an undesirable consequence of urbanization, energy conservation, indoor bioaerosol contamination, and use of synthetic materials and new technologies, and has become a worldwide concern. It is important to comprehend not only the diversity of pollutant hazards but also to develop novel methods and approaches that establish dose-response relationships, cause-and-effect relationships, and clinical relevance. Coincident with heightened public concern over indoor air pollution and its health consequences, a revolution in immunology has occurred. The immune system is recognized as an essential defensive and homeostatic mechanism. Unfortunately, the immune apparatus is exquisitely sensitive to toxic damage. Equally important, among the disciplines available to assess the health impact of indoor air pollutants, immunology has the capability to provide sensitive and specific tools that may accurately measure relevant clinical effects at tissue, cellular, and molecular levels. Furthermore, exciting new insights into shared communications networks between the immune, endocrine, and central nervous systems may provide future explanations for the myriad human complaints associated with indoor air pollutants."
27565,Coniglio et al. 1990,"Urinary excretion of chromium, an index of exposure",,"Urinary excretion of chromium, an index of exposure Abs: "
20714,Buckley et al. 2001,Evaluation of methyl tert-butyl ether (MTBE) as an interference on commercial breath-alcohol analyzers,"Anecdotal reports suggest that high environmental or occupational exposures to the fuel oxygenate methyl tert-butyl ether (MTBE) may result in breath concentrations that are sufficiently elevated to cause a false positive on commercial breath-alcohol analyzers. We evaluated this possibility in vitro by establishing a response curve for simulated breath containing MTBE in ethanol. Two types of breath-alcohol analyzers were evaluated. One analyzer's principle of operation involves in situ wet chemistry (oxidation of ethanol in a potassium dichromate solution) and absorption of visible light. The second instrument uses a combination of infrared absorption and an electrochemical sensor. Both types of instruments are currently used, although the former method represents older technology while the latter method represents newer technology. The percent blood alcohol response curve was evaluated over a breath concentration range thought to be relevant to high-level environmental or occupational exposure (0-361 Ág/l). Results indicate that MTBE positively biases the response of the older technology Breathalyzer(TM) when evaluated as a single constituent or in combination with ethanol. We conclude that a false positive is possible on this instrument if the MTBE exposure is very high, recent with respect to testing, and occurs in combination with ethanol consumption. The interference can be identified on the older technology instrument by a time dependent post-reading increase in the instrument response that does not occur for ethanol alone. In contrast, the newer technology instrument using infrared and electrochemical detectors did not respond to MTBE at lower levels (0-36 Ág/l), and at higher levels (>72 Ág/l) the instrument indicated an ""interference"" or ""error"". For this instrument, a false positive does not occur even at high MTBE levels in the presence of ethanol.","Evaluation of methyl tert-butyl ether (MTBE) as an interference on commercial breath-alcohol analyzers Abs: Anecdotal reports suggest that high environmental or occupational exposures to the fuel oxygenate methyl tert-butyl ether (MTBE) may result in breath concentrations that are sufficiently elevated to cause a false positive on commercial breath-alcohol analyzers. We evaluated this possibility in vitro by establishing a response curve for simulated breath containing MTBE in ethanol. Two types of breath-alcohol analyzers were evaluated. One analyzer's principle of operation involves in situ wet chemistry (oxidation of ethanol in a potassium dichromate solution) and absorption of visible light. The second instrument uses a combination of infrared absorption and an electrochemical sensor. Both types of instruments are currently used, although the former method represents older technology while the latter method represents newer technology. The percent blood alcohol response curve was evaluated over a breath concentration range thought to be relevant to high-level environmental or occupational exposure (0-361 Ág/l). Results indicate that MTBE positively biases the response of the older technology Breathalyzer(TM) when evaluated as a single constituent or in combination with ethanol. We conclude that a false positive is possible on this instrument if the MTBE exposure is very high, recent with respect to testing, and occurs in combination with ethanol consumption. The interference can be identified on the older technology instrument by a time dependent post-reading increase in the instrument response that does not occur for ethanol alone. In contrast, the newer technology instrument using infrared and electrochemical detectors did not respond to MTBE at lower levels (0-36 Ág/l), and at higher levels (>72 Ág/l) the instrument indicated an ""interference"" or ""error"". For this instrument, a false positive does not occur even at high MTBE levels in the presence of ethanol."
20500,Howard et al. 1991,Induction of chromosome changes by metal compounds in cultured CHO cells,"The effect of 4 metal salts on the induction of chromosome aberrations and sister chromatid exchange (SCE) in cultured Chinese hamster ovary (CHO) cells was investigated. It was observed that CdCl2, NiCl2, CrO3 and HgCl2 were effective in causing various types of chromosome aberrations. The percentages of abnormalities increased with increasing doses of the metals used. These metal compounds also raised the SCE rates compared to 5-bromo-2'-deoxyuridine controls. The importance of rapid screening of potentially hazardous metals is described.","Induction of chromosome changes by metal compounds in cultured CHO cells Abs: The effect of 4 metal salts on the induction of chromosome aberrations and sister chromatid exchange (SCE) in cultured Chinese hamster ovary (CHO) cells was investigated. It was observed that CdCl2, NiCl2, CrO3 and HgCl2 were effective in causing various types of chromosome aberrations. The percentages of abnormalities increased with increasing doses of the metals used. These metal compounds also raised the SCE rates compared to 5-bromo-2'-deoxyuridine controls. The importance of rapid screening of potentially hazardous metals is described."
20414,Umeda and  Nishimura 1979,Inducibility of chromosomal aberrations by metal compounds in cultured mammalian cells,"HEEP COPYRIGHT: BIOL ABS. Metal compounds were tested for their ability to induce chromosomal aberrations in cultured mammalian (C3H mouse mammary carinoma FM3A) cells. Chromosomal aberrations were induced by the application of some Cr, Mn and Ni compounds (suspected environmental carcinogens). Among 6-valent Cr compounds, K2Cr2O7 and CrO3 induced high levels of aberrations, at rates which were similar for Cr-equivalent doses. The perchromate compounds were more efficient in producing chromosomal aberrations than was a chromate compound, K2CrO4. A 3-valent Cr compound, Cr2(SO4)3, was less toxic and failed to induce a demonstrable increase in chromosomal aberrations. KMnO4 induced aberrations, but at a low rate. As to Ni compounds, NiCl2 and (CH3COO)2Ni induced few aberrations. Administration of K2Ni(CN)4 induced only gaps. NiS induced a low but definite increase in chromosomal aberrations. The rate of these aberrations increased with an increase in treatment time from 24 to 48 h, indicating a time-dependent increase in the heritable toxicity of metal compounds. CdCl2 and HgCl2 were somewhat toxic, but failed to induce chromosomal aberrations in the present study. (Because these metals are used in industry, applicability to humans is implied.)","Inducibility of chromosomal aberrations by metal compounds in cultured mammalian cells Abs: HEEP COPYRIGHT: BIOL ABS. Metal compounds were tested for their ability to induce chromosomal aberrations in cultured mammalian (C3H mouse mammary carinoma FM3A) cells. Chromosomal aberrations were induced by the application of some Cr, Mn and Ni compounds (suspected environmental carcinogens). Among 6-valent Cr compounds, K2Cr2O7 and CrO3 induced high levels of aberrations, at rates which were similar for Cr-equivalent doses. The perchromate compounds were more efficient in producing chromosomal aberrations than was a chromate compound, K2CrO4. A 3-valent Cr compound, Cr2(SO4)3, was less toxic and failed to induce a demonstrable increase in chromosomal aberrations. KMnO4 induced aberrations, but at a low rate. As to Ni compounds, NiCl2 and (CH3COO)2Ni induced few aberrations. Administration of K2Ni(CN)4 induced only gaps. NiS induced a low but definite increase in chromosomal aberrations. The rate of these aberrations increased with an increase in treatment time from 24 to 48 h, indicating a time-dependent increase in the heritable toxicity of metal compounds. CdCl2 and HgCl2 were somewhat toxic, but failed to induce chromosomal aberrations in the present study. (Because these metals are used in industry, applicability to humans is implied.)"
20386,Rossman et al. 1984,The genetic toxicology of metal compounds: I. Induction of lambda prophage in E coli WP2s(lambda),"A number of metal compounds have been shown to be human carcinogens. Others, while not proven human carcinogens, are able to cause tumors in laboratory animals. Short-term bacterial assays for genotoxic effects have not been successful in predicting the carcinogenicity of metal compounds. We report here the ability of some metal compounds to cause the induction of lamda prophage in E coli WP2S(lamda). By far the strongest inducing ability was observed with K2CrO4, followed by Pb(N03)2 > MnCl2 > Ni(OOCCH3)2 > CrCl2 > NaWO4 > Na2MoO4 > KMnO4. With the exception of chromate, long-term exposures in a narrow, subtoxic dose range were required in order to demonstrate phage induction. A new microtiter assay for lamda prophage induction, which incorporates these features, is described. This system also was able to detect very small amounts of organic carcinogens.","The genetic toxicology of metal compounds: I. Induction of lambda prophage in E coli WP2s(lambda) Abs: A number of metal compounds have been shown to be human carcinogens. Others, while not proven human carcinogens, are able to cause tumors in laboratory animals. Short-term bacterial assays for genotoxic effects have not been successful in predicting the carcinogenicity of metal compounds. We report here the ability of some metal compounds to cause the induction of lamda prophage in E coli WP2S(lamda). By far the strongest inducing ability was observed with K2CrO4, followed by Pb(N03)2 > MnCl2 > Ni(OOCCH3)2 > CrCl2 > NaWO4 > Na2MoO4 > KMnO4. With the exception of chromate, long-term exposures in a narrow, subtoxic dose range were required in order to demonstrate phage induction. A new microtiter assay for lamda prophage induction, which incorporates these features, is described. This system also was able to detect very small amounts of organic carcinogens."
20384,Robison et al. 1984,Analysis of metal-induced DNA lesions and DNA-repair replication in mammalian cells,"The potency of several metal compounds in causing lesions in DNA either directly or by exposure of intact cultured cells has been examined using the neutral conditions of nucleoid gradient sedimentation. HgCl2 was clearly the most potent inducer of single-strand breakage when added to isolated nucleoids or when nucleoids were prepared from cells treated with this compound. CaCrO4, however, caused DNA-strand breaks in nucleoids isolated from cells treated with this agent but did not induce DNA strand breaks when added directly to nucleoids. Although less potent than HgCl2, NiCl2 also caused significant single strand breakage in isolated nucleoids or in nucleoids prepared from cells treated with this metal. Since strand breakage of DNA in intact cells may occur secondary to activation of DNA-dependent nucleases during repair replication, CsCl gradient density sedimentation was utilized to examine whether repair processes were induced by exposure of cells to NiCl2, HgCl2 and CaCrO4. CaCrO4 and NiCl2 induced substantial DNA-repair activity at concentrations and exposure times where DNA lesions could not be detected whereas HgCl2 induced a 10-fold lower level of DNA-repair activity compared to CaCrO4 at optimal concentrations which again were below the concentrations of this metal that produced measurable DNA lesions. Both the induction of DNA-repair activity and DNA-strand breakage by these metals was concentration- and time-dependent. These results demonstrate some unique aspects of the interaction of HgCl2, NiCl2 and CaCrO4 with the DNA of intact cells and point to the possible important correlation of induction of DNA repair to carcinogenesis since nickel and chromate have clearly been implicated as carcinogens and induce considerable repair whereas HgCl2 is not considered a carcinogen and induces the least DNA repair despite its potency in producing DNA lesions.","Analysis of metal-induced DNA lesions and DNA-repair replication in mammalian cells Abs: The potency of several metal compounds in causing lesions in DNA either directly or by exposure of intact cultured cells has been examined using the neutral conditions of nucleoid gradient sedimentation. HgCl2 was clearly the most potent inducer of single-strand breakage when added to isolated nucleoids or when nucleoids were prepared from cells treated with this compound. CaCrO4, however, caused DNA-strand breaks in nucleoids isolated from cells treated with this agent but did not induce DNA strand breaks when added directly to nucleoids. Although less potent than HgCl2, NiCl2 also caused significant single strand breakage in isolated nucleoids or in nucleoids prepared from cells treated with this metal. Since strand breakage of DNA in intact cells may occur secondary to activation of DNA-dependent nucleases during repair replication, CsCl gradient density sedimentation was utilized to examine whether repair processes were induced by exposure of cells to NiCl2, HgCl2 and CaCrO4. CaCrO4 and NiCl2 induced substantial DNA-repair activity at concentrations and exposure times where DNA lesions could not be detected whereas HgCl2 induced a 10-fold lower level of DNA-repair activity compared to CaCrO4 at optimal concentrations which again were below the concentrations of this metal that produced measurable DNA lesions. Both the induction of DNA-repair activity and DNA-strand breakage by these metals was concentration- and time-dependent. These results demonstrate some unique aspects of the interaction of HgCl2, NiCl2 and CaCrO4 with the DNA of intact cells and point to the possible important correlation of induction of DNA repair to carcinogenesis since nickel and chromate have clearly been implicated as carcinogens and induce considerable repair whereas HgCl2 is not considered a carcinogen and induces the least DNA repair despite its potency in producing DNA lesions."
20366,Ohno et al. 1982,Inducibility of sister-chromatid exchanges by heavy-metal ions,HEEP COPYRIGHT: BIOL ABS. CHINESE HAMSTER LUNG DON CELL CHROMIUM IRON NICKEL SELENIUM CADMIUM MERCURY ARSENIC TITANIUM ZIRCONIUM TIN CARCINOGENICITY,Inducibility of sister-chromatid exchanges by heavy-metal ions Abs: HEEP COPYRIGHT: BIOL ABS. CHINESE HAMSTER LUNG DON CELL CHROMIUM IRON NICKEL SELENIUM CADMIUM MERCURY ARSENIC TITANIUM ZIRCONIUM TIN CARCINOGENICITY
20360,Nishimura and  Umeda 1978,Mutagenic effect of some metal compounds on cultured mammalian cells,HEEP COPYRIGHT: BIOL ABS. ABSTRACT C-3H MOUSE MAMMARY CARCINOMA FM-3A CELL CHROMIUM TRI OXIDE POTASSIUM CHROMATE POTASSIUM DI CHROMATE POTASSIUM PER MANGANATE 8 AZA GUANINE RESISTANCE,Mutagenic effect of some metal compounds on cultured mammalian cells Abs: HEEP COPYRIGHT: BIOL ABS. ABSTRACT C-3H MOUSE MAMMARY CARCINOMA FM-3A CELL CHROMIUM TRI OXIDE POTASSIUM CHROMATE POTASSIUM DI CHROMATE POTASSIUM PER MANGANATE 8 AZA GUANINE RESISTANCE
20343,Marzin and  Phi 1985,Study of the mutagenicity of metal derivatives with Salmonella typhimurium TA102,"The mutagenic potential of 16 metal derivatives was studied with a new mutant of Salmonella typhimurium, the strain TA102 (Levin et al., 1983). Some of these compounds are known as carcinogens (As, Cr VI, Cd, Ni) or suspected carcinogens in man (Pb, Hg), others are known as non-carcinogens (Cr III, Al, Cu, Mn, Fe). Among these 16 derivatives, only the two Cr(VI) compounds are strong mutagens (K2Cr2O7 or K2CrO4).","Study of the mutagenicity of metal derivatives with Salmonella typhimurium TA102 Abs: The mutagenic potential of 16 metal derivatives was studied with a new mutant of Salmonella typhimurium, the strain TA102 (Levin et al., 1983). Some of these compounds are known as carcinogens (As, Cr VI, Cd, Ni) or suspected carcinogens in man (Pb, Hg), others are known as non-carcinogens (Cr III, Al, Cu, Mn, Fe). Among these 16 derivatives, only the two Cr(VI) compounds are strong mutagens (K2Cr2O7 or K2CrO4)."
20318,Kanematsu et al. 1980,REC assay and mutagenicity studies on metal compounds,"We carried out rec assays on 127 metal compounds with Bacillus subtilis to check their DNA-damaging capacity and mutagenicity. Certain compounds of beryllium, cobalt, cesium, iridium, osmium, platinum, rhodium, antimony, tellurium, thallium and vanadium were newly found to be positive in addition to those of known positive metals such as arsenic, cadmium, chromium, mercury, molybdenum and selenium. Reverse mutation assays with Escherichia coli and Salmonella strains showed that compounds of rhodium (RhCl3), tellurium (Na2H4TeO6, Na2TeO3) and platinum (PtCl4, (NH4)2PtCl6) are potent mutagens.","REC assay and mutagenicity studies on metal compounds Abs: We carried out rec assays on 127 metal compounds with Bacillus subtilis to check their DNA-damaging capacity and mutagenicity. Certain compounds of beryllium, cobalt, cesium, iridium, osmium, platinum, rhodium, antimony, tellurium, thallium and vanadium were newly found to be positive in addition to those of known positive metals such as arsenic, cadmium, chromium, mercury, molybdenum and selenium. Reverse mutation assays with Escherichia coli and Salmonella strains showed that compounds of rhodium (RhCl3), tellurium (Na2H4TeO6, Na2TeO3) and platinum (PtCl4, (NH4)2PtCl6) are potent mutagens."
20297,Galloway and  Ivett 1986,Chemically induced aneuploidy in mammalian cells in culture,BIOSIS COPYRIGHT: BIOL ABS. RRM REVIEW MUTAGENICITY TESTING,Chemically induced aneuploidy in mammalian cells in culture Abs: BIOSIS COPYRIGHT: BIOL ABS. RRM REVIEW MUTAGENICITY TESTING
20265,Christie et al. 1984,Use of mammalian DNA repair-deficient mutants to assess the effects of toxic metal compounds on DNA,,Use of mammalian DNA repair-deficient mutants to assess the effects of toxic metal compounds on DNA Abs: 
20258,Casto et al. 1979,Enhancement of viral transformation for evaluation of the carcinogenic or mutagenic potential of inorganic metal salts,"Thirty-eight metal salts were tested for their capacity to enhance transformation of Syrian hamster embryo cells by a simian adenovirus, SA7. All of the metal salts with known carcinogenic potential in animals or mutagenic activity in microbial or mammalian cells increased the SA7 transformation frequency. Metals were classified into three groups according to the concentration necessary to produce significant enhancement. Those showing highest activity (positive at less than 0.05 mM) were the salts of antimony, arsenic, cadmium, chromium, and platinum. The second group (positive from 0.05 to 0.6 mM) included beryllium, cobalt, copper, lead, manganese, mercury, nickel, silver, thallium, and zinc. Iron salts were placed in a third group (only positive at concentrations greater than 0.9 mM). With the exception of ZnCl2 and ZnSO4, enhancement was demonstrated by both a relative increase in the viral transformation frequency and an absolute increase in the number of transformed foci among treated cells. The latter observation and the demonstration of enhancement in the absence of overt cell killing negate the possibility that enhancement resulted from the selection of transformation-sensitive cells.","Enhancement of viral transformation for evaluation of the carcinogenic or mutagenic potential of inorganic metal salts Abs: Thirty-eight metal salts were tested for their capacity to enhance transformation of Syrian hamster embryo cells by a simian adenovirus, SA7. All of the metal salts with known carcinogenic potential in animals or mutagenic activity in microbial or mammalian cells increased the SA7 transformation frequency. Metals were classified into three groups according to the concentration necessary to produce significant enhancement. Those showing highest activity (positive at less than 0.05 mM) were the salts of antimony, arsenic, cadmium, chromium, and platinum. The second group (positive from 0.05 to 0.6 mM) included beryllium, cobalt, copper, lead, manganese, mercury, nickel, silver, thallium, and zinc. Iron salts were placed in a third group (only positive at concentrations greater than 0.9 mM). With the exception of ZnCl2 and ZnSO4, enhancement was demonstrated by both a relative increase in the viral transformation frequency and an absolute increase in the number of transformed foci among treated cells. The latter observation and the demonstration of enhancement in the absence of overt cell killing negate the possibility that enhancement resulted from the selection of transformation-sensitive cells."
20256,Cantoni et al. 1986,Regulatory role of extracellular medium components in metal induced cyto- and geno-toxicity,"The effects of extracellular medium components on the toxicity of metal ions was characterized, and cytotoxic and genotoxic actions produced by mercuric-chloride (7487947) (HgCl2) or calcium-chromate (13765190) (CaCrO4) were studied in Chinese-hamster ovary (CHO) cells grown as monolayer cultures. For a given HgCl2 concentration, the amount of DNA damage was highly dependent on the composition of the extracellular milieu. DNA breakage produced by HgCl2 was markedly reduced by addition of either reduced glutathione (1 millimolar (mM)) or cysteine (5mM). The growth inhibitory effect of HgCl2 was significantly reduced by cysteine. The effect of medium was less dramatic in the case of CaCrO4. DNA breakage and the cell killing effect of chromate was reduced by addition of ascorbic-acid (0.5mM). It is concluded that genotoxic and cytotoxic actions produced by metal compounds are modulated by the composition of the extracellular medium. It is stated that Hg(2+) ions show a strong affinity for sulfhydryl and disulfide groups of proteins or nonprotein medium components. Trivalent chromium is significantly less potent than hexavalent forms, since the cell membrane is relatively impermeable to the trivalent form. The authors conclude that in-vitro studies of metal carcinogenesis from different laboratories or even using different lots of serum should be interpreted with caution.","Regulatory role of extracellular medium components in metal induced cyto- and geno-toxicity Abs: The effects of extracellular medium components on the toxicity of metal ions was characterized, and cytotoxic and genotoxic actions produced by mercuric-chloride (7487947) (HgCl2) or calcium-chromate (13765190) (CaCrO4) were studied in Chinese-hamster ovary (CHO) cells grown as monolayer cultures. For a given HgCl2 concentration, the amount of DNA damage was highly dependent on the composition of the extracellular milieu. DNA breakage produced by HgCl2 was markedly reduced by addition of either reduced glutathione (1 millimolar (mM)) or cysteine (5mM). The growth inhibitory effect of HgCl2 was significantly reduced by cysteine. The effect of medium was less dramatic in the case of CaCrO4. DNA breakage and the cell killing effect of chromate was reduced by addition of ascorbic-acid (0.5mM). It is concluded that genotoxic and cytotoxic actions produced by metal compounds are modulated by the composition of the extracellular medium. It is stated that Hg(2+) ions show a strong affinity for sulfhydryl and disulfide groups of proteins or nonprotein medium components. Trivalent chromium is significantly less potent than hexavalent forms, since the cell membrane is relatively impermeable to the trivalent form. The authors conclude that in-vitro studies of metal carcinogenesis from different laboratories or even using different lots of serum should be interpreted with caution."
20241,Arlauskas et al. 1985,Mutagenicity of metal ions in bacteria,"The mutagenicity of 24 metal salts was investigated in plate incorporation and fluctuation assays with Salmonella TA strains or Escherichia coli WP2 uvrA pKm 101. Chromate(VI) and selenate(VI) ions were found to be mutagenic in plate incorporation assays employing conventional media. On the other hand, cadmium(II), beryllium(II), chromate(VI), and metavanadate(V) ions were detected in conventional fluctuation assays, indicating the importance of this technique in detection of metal mutagens. Modified culture media, with trimetaphosphate ions in place of orthophosphate as the sole phosphate source for bacterial growth, were also used in this study. The media modifications prevented precipitation of metals such as nickel and cadmium as their insoluble phosphates, and allowed detection of the mutagenicity of metavanadate ions in plate incorporation assays. However, the fluctuation technique using standard media was shown to detect a wider range of mutagenic metal ions than tests with modified media. It is notable that metaarsenite(III), arsenate(V), and nickel(II) ions were not found to be mutagenic in any of the assays although they are known to be carcinogenic and are mutagenic in other test systems. Their lack of mutagenicity in the modified media indicates that precipitation of these ions as orthophosphates is not the reason for their lack of activity in standard bacterial assays.","Mutagenicity of metal ions in bacteria Abs: The mutagenicity of 24 metal salts was investigated in plate incorporation and fluctuation assays with Salmonella TA strains or Escherichia coli WP2 uvrA pKm 101. Chromate(VI) and selenate(VI) ions were found to be mutagenic in plate incorporation assays employing conventional media. On the other hand, cadmium(II), beryllium(II), chromate(VI), and metavanadate(V) ions were detected in conventional fluctuation assays, indicating the importance of this technique in detection of metal mutagens. Modified culture media, with trimetaphosphate ions in place of orthophosphate as the sole phosphate source for bacterial growth, were also used in this study. The media modifications prevented precipitation of metals such as nickel and cadmium as their insoluble phosphates, and allowed detection of the mutagenicity of metavanadate ions in plate incorporation assays. However, the fluctuation technique using standard media was shown to detect a wider range of mutagenic metal ions than tests with modified media. It is notable that metaarsenite(III), arsenate(V), and nickel(II) ions were not found to be mutagenic in any of the assays although they are known to be carcinogenic and are mutagenic in other test systems. Their lack of mutagenicity in the modified media indicates that precipitation of these ions as orthophosphates is not the reason for their lack of activity in standard bacterial assays."
18437,Jenssen and  Ramel 1980,The micronucleus test as part of a short-term mutagenicity test program for the predicition of carcinogenicity evaluated by 143 agents tested,"To evaluate the usefulness of the micronucleus test as a short-term assay for the detection of carcinogens, the correlation between micronucleus test data for 143 chemicals and corresponding cancer data, has been analyzed. For comparison, analogous data from Ames's test have also been collected for the same chemicals. In a comparison of the micronucleus test and Ames's test it was found that they had about the same specificity (around 80%) and predictive value (around 90%), while there was a significant difference in sensitivity in favor of Ames's test. The difference in sensitivity could be partly explained by differences in metabolizing capacities of these two test systems. It is concluded that a more elaborate test procedure for the micronucleus test would increase that sensitivity of this test. The principal value of the micronucleus test lies in the fact that it is an in vivo method, which may pick up effects at the chromosomal level not covered by bacterial assays. This is emphasized by the finding that the combination of Ames's test and the micronucleus test did increase the sensitivity of the screening procedure for the prediction of carcinogenic effects.","The micronucleus test as part of a short-term mutagenicity test program for the predicition of carcinogenicity evaluated by 143 agents tested Abs: To evaluate the usefulness of the micronucleus test as a short-term assay for the detection of carcinogens, the correlation between micronucleus test data for 143 chemicals and corresponding cancer data, has been analyzed. For comparison, analogous data from Ames's test have also been collected for the same chemicals. In a comparison of the micronucleus test and Ames's test it was found that they had about the same specificity (around 80%) and predictive value (around 90%), while there was a significant difference in sensitivity in favor of Ames's test. The difference in sensitivity could be partly explained by differences in metabolizing capacities of these two test systems. It is concluded that a more elaborate test procedure for the micronucleus test would increase that sensitivity of this test. The principal value of the micronucleus test lies in the fact that it is an in vivo method, which may pick up effects at the chromosomal level not covered by bacterial assays. This is emphasized by the finding that the combination of Ames's test and the micronucleus test did increase the sensitivity of the screening procedure for the prediction of carcinogenic effects."
18253,Hewitt and  Brown 1984,Nephrotoxic interactions between ketonic solvents and halogenated aliphatic chemicals,"Recent studies have indicated that (1) ketonic solvents and ketogenic chemicals can potentiate the nephrotoxic and hepatotoxic effects of one or more halogenated hydrocarbons; and (2) the relative ability of ketones to potentiate the liver injury produced by chloroform (CHCl3) may be influenced by the carbon skeleton length of the ketone. Although five ketones (acetone, 2-butanone, 2-pentanone, 2-hexanone, (HX), and 2-heptanone) increased CHCl3-induced kidney and liver injury in male, Fischer 344 rats, no relationship between ketone chain length and potentiating capacity was observed. HX potentiated the CHCL3-induced depletion of hepatic glutathione content and increased the irreversible binding of 14CHCl3-derived radiolabel to hepatic constituents. In contrast, CHCl3 did not alter glutathione content in the renal cortex of either vehicle- or HX-pretreated rats. Although HX increased the binding of 14C from 14CHCl3 to renal cortical macromolecules, the magnitude of the increase was unremarkable, approaching only the extent of hepatic 14C binding in vehicle-pretreated rats challenged with 14CHCl3. Since the severity of renal and hepatic injury was comparable in rats receiving the combination of HX + CHCl3, it appeared that HX potentiated CHCl3 nephro- and hepatotoxicity by different mechanisms. Ketone pretreatment did not potentiate the renal injury produced by potassium dichromate or hexachloro-1,3-butadiene.","Nephrotoxic interactions between ketonic solvents and halogenated aliphatic chemicals Abs: Recent studies have indicated that (1) ketonic solvents and ketogenic chemicals can potentiate the nephrotoxic and hepatotoxic effects of one or more halogenated hydrocarbons; and (2) the relative ability of ketones to potentiate the liver injury produced by chloroform (CHCl3) may be influenced by the carbon skeleton length of the ketone. Although five ketones (acetone, 2-butanone, 2-pentanone, 2-hexanone, (HX), and 2-heptanone) increased CHCl3-induced kidney and liver injury in male, Fischer 344 rats, no relationship between ketone chain length and potentiating capacity was observed. HX potentiated the CHCL3-induced depletion of hepatic glutathione content and increased the irreversible binding of 14CHCl3-derived radiolabel to hepatic constituents. In contrast, CHCl3 did not alter glutathione content in the renal cortex of either vehicle- or HX-pretreated rats. Although HX increased the binding of 14C from 14CHCl3 to renal cortical macromolecules, the magnitude of the increase was unremarkable, approaching only the extent of hepatic 14C binding in vehicle-pretreated rats challenged with 14CHCl3. Since the severity of renal and hepatic injury was comparable in rats receiving the combination of HX + CHCl3, it appeared that HX potentiated CHCl3 nephro- and hepatotoxicity by different mechanisms. Ketone pretreatment did not potentiate the renal injury produced by potassium dichromate or hexachloro-1,3-butadiene."
17980,S et al. 1984,Genotoxic activity and potency of 135 compounds in the Ames reversion test and in a bacterial DNA-repair test,"Compounds of various chemical classes were comparatively assayed in the Ames reversion test with his- S. typhimurium strains TA1535, TA157 , TA1538, TA98, TA100, and, in part, TA97 , and in a DNA-repair test with trp- E. coli strains WP2 (repair-proficient), WP67 (uvrA- polA-) and CM871 (uvrA- recA- lexA-). A liquid micromethod procedure for the assessment of the minimal inhibitory concentration (MIC) of test compounds, using the same reagents as the Ames test, was set up and calibrated in its technical details. Other techniques (spot test and treat-and-plate method) were applied to a number of compounds in order to obtain more complete information on their DNA-damaging activity in E. coli. From a qualitative standpoint, the results obtained in the reversion test and in the DNA-repair test (liquid micromethod) were overlapping for 96 (59 positive and 37 negative) out of 135 compounds (71.1%). There was disagreement for 39 compounds (28.9%), 9 of which were positive only in the reversion test (8 requiring metabolic activation and 5 genotoxic in the treat-and-plate method). 30 compounds were positive only in the lethality test, showing a direct DNA-damaging activity, which in half of the cases was completely eliminated by S9 mix. Although the experimental protocol intentionally included several compounds already reported as nonmutagenic carcinogens or as noncarcinogenic mutagens, the overall accuracy was 64.5% for the reversion test and 72.4% for the DNA-repair test, as evaluated for 75 compounds classified according to their carcinogenic activity. Quantitation of results was obtained in the Ames test by relating the net number of revertants to nmoles of compound and in the DNA-repair test by means of a formula relating the difference and ratio of MICs in repair-proficient and -deficient bacteria to nmoles of compound. Following these criteria, the genotoxic potency varied over a 4.5 X 10(7)-fold range among compounds positive in the reversion test and over a 6 X 10(9)-fold range among compounds damaging E. coli DNA. The genotoxic potencies in the two bacterial systems were correlated within the majority of the chemical classes under scrutiny.","Genotoxic activity and potency of 135 compounds in the Ames reversion test and in a bacterial DNA-repair test Abs: Compounds of various chemical classes were comparatively assayed in the Ames reversion test with his- S. typhimurium strains TA1535, TA157 , TA1538, TA98, TA100, and, in part, TA97 , and in a DNA-repair test with trp- E. coli strains WP2 (repair-proficient), WP67 (uvrA- polA-) and CM871 (uvrA- recA- lexA-). A liquid micromethod procedure for the assessment of the minimal inhibitory concentration (MIC) of test compounds, using the same reagents as the Ames test, was set up and calibrated in its technical details. Other techniques (spot test and treat-and-plate method) were applied to a number of compounds in order to obtain more complete information on their DNA-damaging activity in E. coli. From a qualitative standpoint, the results obtained in the reversion test and in the DNA-repair test (liquid micromethod) were overlapping for 96 (59 positive and 37 negative) out of 135 compounds (71.1%). There was disagreement for 39 compounds (28.9%), 9 of which were positive only in the reversion test (8 requiring metabolic activation and 5 genotoxic in the treat-and-plate method). 30 compounds were positive only in the lethality test, showing a direct DNA-damaging activity, which in half of the cases was completely eliminated by S9 mix. Although the experimental protocol intentionally included several compounds already reported as nonmutagenic carcinogens or as noncarcinogenic mutagens, the overall accuracy was 64.5% for the reversion test and 72.4% for the DNA-repair test, as evaluated for 75 compounds classified according to their carcinogenic activity. Quantitation of results was obtained in the Ames test by relating the net number of revertants to nmoles of compound and in the DNA-repair test by means of a formula relating the difference and ratio of MICs in repair-proficient and -deficient bacteria to nmoles of compound. Following these criteria, the genotoxic potency varied over a 4.5 X 10(7)-fold range among compounds positive in the reversion test and over a 6 X 10(9)-fold range among compounds damaging E. coli DNA. The genotoxic potencies in the two bacterial systems were correlated within the majority of the chemical classes under scrutiny."
17755,Grant and  Mushak 1989,Specification of metals and metal compounds: implications for biological monitoring and development of regulatory approaches,"Illustrative examples of toxic, form specific metals or metalloids and their implications for biological monitoring and development of regulatory approaches were considered. Topics included: form variable metals in external environmental media; nickel (7440020) and its compounds, biokinetic differences among inorganic nickel and its compounds, biological monitoring and the carcinogenicity of nickel compounds, implications for biological monitoring; mercury (7439976) and its compounds, biokinetic differences among selected mercury forms, biological monitoring and the toxicology of selected mercurials, current biological monitoring approaches with human exposure to mercurials, implications of speciation for future biological monitoring; chromium (7440473) and its compounds, biokinetic differences between trivalent and hexavalent chromium, biological monitoring and the toxicology of chromium compounds, implications for biological monitoring; and in-vivo biotransformation of metals and metalloids, biomethylation of inorganic-arsenic (7440382) in humans and experimental animals, oxidation reduction of inorganic arsenic in mammalian systems, and implications for biological monitoring. The authors conclude that there is a need for careful consideration of speciation issues in regard to determining the usefulness of biological monitoring for certain metals or metalloids. In some cases, indiscriminate whole metal analyses would be of little or no value in providing useful indices of exposure for purposes of risk assessment or risk management.","Specification of metals and metal compounds: implications for biological monitoring and development of regulatory approaches Abs: Illustrative examples of toxic, form specific metals or metalloids and their implications for biological monitoring and development of regulatory approaches were considered. Topics included: form variable metals in external environmental media; nickel (7440020) and its compounds, biokinetic differences among inorganic nickel and its compounds, biological monitoring and the carcinogenicity of nickel compounds, implications for biological monitoring; mercury (7439976) and its compounds, biokinetic differences among selected mercury forms, biological monitoring and the toxicology of selected mercurials, current biological monitoring approaches with human exposure to mercurials, implications of speciation for future biological monitoring; chromium (7440473) and its compounds, biokinetic differences between trivalent and hexavalent chromium, biological monitoring and the toxicology of chromium compounds, implications for biological monitoring; and in-vivo biotransformation of metals and metalloids, biomethylation of inorganic-arsenic (7440382) in humans and experimental animals, oxidation reduction of inorganic arsenic in mammalian systems, and implications for biological monitoring. The authors conclude that there is a need for careful consideration of speciation issues in regard to determining the usefulness of biological monitoring for certain metals or metalloids. In some cases, indiscriminate whole metal analyses would be of little or no value in providing useful indices of exposure for purposes of risk assessment or risk management."
16152,Purser and  Hume 1994,Detection--analytical,"The federal government has made it necessary for environmental pollutants to be identified and quantified to determine that compliance to regulations are within acceptable tolerance limits. Since the industrial revolution began, man has been making or dumping chemicals into the environment, contaminating the air we breathe, the water we drink, and the soil on which we live. By nature or man's design, many of these chemicals such as pesticides are intended for the destruction of undesirable animal and plant life, but can in certain concentrations present a hazard to human life. Fortunately, many persons finally became concerned and unified enough to act about the pollution of their environment. In 1969 the National Environmental Policy Act (NEAP) was passed. In 1970, it was followed by the formation of the U.S. Environmental Protection Agency (EPA). This was the beginning of a proliferation of federal and state legislation to be passed for the benefit of our environment (Cram, 1989; Ryan, 1989). ..... Our intention in this chapter is to describe some of the methods used by the EPA and others to analyze the various air, water, and soil samples for environmental pollutants such as the analyses of metals, petroleum, solvents, pesticides, halogenated aromatic compounds, inorganic substances, and herbicides.","Detection--analytical Abs: The federal government has made it necessary for environmental pollutants to be identified and quantified to determine that compliance to regulations are within acceptable tolerance limits. Since the industrial revolution began, man has been making or dumping chemicals into the environment, contaminating the air we breathe, the water we drink, and the soil on which we live. By nature or man's design, many of these chemicals such as pesticides are intended for the destruction of undesirable animal and plant life, but can in certain concentrations present a hazard to human life. Fortunately, many persons finally became concerned and unified enough to act about the pollution of their environment. In 1969 the National Environmental Policy Act (NEAP) was passed. In 1970, it was followed by the formation of the U.S. Environmental Protection Agency (EPA). This was the beginning of a proliferation of federal and state legislation to be passed for the benefit of our environment (Cram, 1989; Ryan, 1989). ..... Our intention in this chapter is to describe some of the methods used by the EPA and others to analyze the various air, water, and soil samples for environmental pollutants such as the analyses of metals, petroleum, solvents, pesticides, halogenated aromatic compounds, inorganic substances, and herbicides."
14661,Suzuki 1987,Anion-exchange high-performance liquid chromatography of water-soluble chromium(VI) and chromium(III) complexes in biological materials,"The application of an anion exchange high performance liquid chromatographic procedure to the simultaneous determination of water soluble hexavalent-chromium (1854O299) (Cr+6) and trivalent-chromium (16065831) (Cr+3) complexes in biological samples was described. Plasma, erythrocyte lysate, and the 105000-g liver supernatant obtained from male Sprague-Dawley-rats were incubated with sodium-chromate (7775113) or chromium(III)-chloride (10025737) for up to 120 minutes. After incubation, liver supernatant, plasma and erythrocyte lysate were injected into a high performance liquid chromatograph (HPLC) interfaced to a visible spectrophotometer, an ultraviolet (UV) spectrophotometer, and an atomic absorption spectrometer (AAS). Cr+6 separated by HPLC was continuously determined by visible spectrophotometry at 370 nanometers (nm) and AAS. The separation patterns of the other species were monitored by AAS. Elution of the biological components in the sample was monitored by UV at 280nm. When standard Cr+6 solutions were tested, the detection limits for visible spectrometry and AAS were 2 and 5 nanograms, respectively. When aliquots of the biological materials were examined after varying periods of incubation, time related decreases of Cr+6 peaks accompanied by increases in Cr+3 peak intensities were seen. These changes were attributed to biological reduction of Cr+6 to Cr+3. Cr+6 reduction rates were highest in the supernatant, followed by the erythrocyte lysate and plasma, in that order. The author concludes that anion exchange HPLC is useful for simultaneously determining Cr+6 and Cr+3 in biological samples.","Anion-exchange high-performance liquid chromatography of water-soluble chromium(VI) and chromium(III) complexes in biological materials Abs: The application of an anion exchange high performance liquid chromatographic procedure to the simultaneous determination of water soluble hexavalent-chromium (1854O299) (Cr+6) and trivalent-chromium (16065831) (Cr+3) complexes in biological samples was described. Plasma, erythrocyte lysate, and the 105000-g liver supernatant obtained from male Sprague-Dawley-rats were incubated with sodium-chromate (7775113) or chromium(III)-chloride (10025737) for up to 120 minutes. After incubation, liver supernatant, plasma and erythrocyte lysate were injected into a high performance liquid chromatograph (HPLC) interfaced to a visible spectrophotometer, an ultraviolet (UV) spectrophotometer, and an atomic absorption spectrometer (AAS). Cr+6 separated by HPLC was continuously determined by visible spectrophotometry at 370 nanometers (nm) and AAS. The separation patterns of the other species were monitored by AAS. Elution of the biological components in the sample was monitored by UV at 280nm. When standard Cr+6 solutions were tested, the detection limits for visible spectrometry and AAS were 2 and 5 nanograms, respectively. When aliquots of the biological materials were examined after varying periods of incubation, time related decreases of Cr+6 peaks accompanied by increases in Cr+3 peak intensities were seen. These changes were attributed to biological reduction of Cr+6 to Cr+3. Cr+6 reduction rates were highest in the supernatant, followed by the erythrocyte lysate and plasma, in that order. The author concludes that anion exchange HPLC is useful for simultaneously determining Cr+6 and Cr+3 in biological samples."
14648,Harzdorf 1987,"Analytical chemistry of chromium species in the environment, and interpretation of results",,"Analytical chemistry of chromium species in the environment, and interpretation of results Abs: "
14638,Wetterhahn et al. 1989,Mechanism of chromium(VI) carcinogenesis: Reactive intermediates and effect on gene expression,"Since chromium(VI) is unreactive toward DNA under physiological conditions in vitro, the ability of carcinogenic chromium(VI) compounds to damage DNA depends on the presence of cellular redox components that reduce chromium(VI) to reactive species capable of interacting with DNA. We have examined the role of glutathione and hydrogen peroxide in chromium(VI)-induced DNA damage in vitro. Upon reaction with chromium(VI), glutathione produced chromium(V) and glutathione thiyl radical reactive intermediates, whereas hydrogen peroxide produced chromium(V) and hydroxyl radical. Reaction of DNA with chromium(VI) in the presence of glutathione resulted in binding of chromium and glutathione to DNA with little or no DNA strand breakage. Reaction of DNA with chromium(VI) in the presence of hydrogen peroxide produced the 8-hydroxydeoxy-guanosine adduct and extensive DNA strand breakage in the absence of significant Cr-DNA adduct formation. These results suggest that the nature of chromium(VI)-induced DNA damage will be strongly dependent on reactive intermediates such as chromium(V), glutathione thiyl radical, and hydroxyl radical, produced by cellular components active in chromium(VI) metabolism. In order to assess the ability of chromium(VI)-induced DNA damage to affect the normal template function of DNA, we investigated the effects of chromium(VI) on steady-state mRNA levels of various genes in chick embryo liver in vivo, and compared the effects to the levels of DNA damage observed. Chromium(VI) induced DNA-protein and DNA interstrand cross-links in chick embryo liver in vivo and suppressed the induction of 5-aminolevulinic acid synthase and cytochrome P-450 mRNA expression by porphyrinogenic drugs. In contrast, chromium(VI) increased the basal levels of expression of these two inducible genes, but had little or no effect on the expression of the constitutive albumin, ?-actin, and conalbumin genes. Comparison of the time course of formation and repair of DNA damage with that of changes in gene expression suggests that chromium(VI) may form a mono-adduct prior to formation of DNA cross-links, and that chromium(VI)-induced DNA lesions may target certain classes of genes and lead to changes in their expression.","Mechanism of chromium(VI) carcinogenesis: Reactive intermediates and effect on gene expression Abs: Since chromium(VI) is unreactive toward DNA under physiological conditions in vitro, the ability of carcinogenic chromium(VI) compounds to damage DNA depends on the presence of cellular redox components that reduce chromium(VI) to reactive species capable of interacting with DNA. We have examined the role of glutathione and hydrogen peroxide in chromium(VI)-induced DNA damage in vitro. Upon reaction with chromium(VI), glutathione produced chromium(V) and glutathione thiyl radical reactive intermediates, whereas hydrogen peroxide produced chromium(V) and hydroxyl radical. Reaction of DNA with chromium(VI) in the presence of glutathione resulted in binding of chromium and glutathione to DNA with little or no DNA strand breakage. Reaction of DNA with chromium(VI) in the presence of hydrogen peroxide produced the 8-hydroxydeoxy-guanosine adduct and extensive DNA strand breakage in the absence of significant Cr-DNA adduct formation. These results suggest that the nature of chromium(VI)-induced DNA damage will be strongly dependent on reactive intermediates such as chromium(V), glutathione thiyl radical, and hydroxyl radical, produced by cellular components active in chromium(VI) metabolism. In order to assess the ability of chromium(VI)-induced DNA damage to affect the normal template function of DNA, we investigated the effects of chromium(VI) on steady-state mRNA levels of various genes in chick embryo liver in vivo, and compared the effects to the levels of DNA damage observed. Chromium(VI) induced DNA-protein and DNA interstrand cross-links in chick embryo liver in vivo and suppressed the induction of 5-aminolevulinic acid synthase and cytochrome P-450 mRNA expression by porphyrinogenic drugs. In contrast, chromium(VI) increased the basal levels of expression of these two inducible genes, but had little or no effect on the expression of the constitutive albumin, ?-actin, and conalbumin genes. Comparison of the time course of formation and repair of DNA damage with that of changes in gene expression suggests that chromium(VI) may form a mono-adduct prior to formation of DNA cross-links, and that chromium(VI)-induced DNA lesions may target certain classes of genes and lead to changes in their expression."
14635,Brescianini et al. 1988,Determination of hexavalent chromium in welding fumes by GFAAS after liquid anion-exchange separation: investigation of interferences,,Determination of hexavalent chromium in welding fumes by GFAAS after liquid anion-exchange separation: investigation of interferences Abs: 
14622,Mikalsen et al. 1989,Microsomal metabolism of hexavalent chromium Inhibitory effect of oxygen and involvement of cytochrome P-450,"The reduction of hexavalent chromium (Cr(VI] by rat liver microsomes was studied. With 15-120 microM Na2CrO4 microsomes (0.5 mg protein/ml) effectively reduced Cr(VI) in the presence of NADPH provided anaerobic conditions. Phenobarbital (PB) and Aroclor 1254 (PCB) pretreatment increased microsomal Cr(VI) reduction while CoCl2 reduced the rate. The rates with 30 microM Na2CrO4 were: 6.4 +/- 0.1, 7.8 +/- 0.7, 13.4 +/- 0.5, 2.95 +/- 0.09 nmol Cr.mg prot.-1 min-1 for control, PB, PCB and cobalt pretreated microsomes respectively. Kinetic studies gave a Michaeli-Menten like first-order kinetics with increases both in Km and Vmax values after pretreatment with PB or PCB. CO partly inhibited the microsomal Cr(VI) reduction. The CO-sensitive reduction rate was directly correlated to the cyt. P-450 content of the different microsomal preparations. Substituting NADH for NADPH gave approximately 27% lower activity with 30 microM Na2CrO4. This activity was neither inducible by cyt. P-450 inducers nor influenced by CO. Oxygen 1.0% and 0.10% gave approximately 100% and 30% inhibition of Cr(VI) reduction (30 microM Na2CrO4) respectively, and an uncompetitive like inhibitory pattern was found. No redox cycling of Cr(VI) was seen. 51Cr binding to the microsomes was approximately 10% after complete reduction of 30 microM Na2CrO4. Externally added FMN, Fe3+-ADP and nitrobenzen stimulated microsomal Cr(VI) reduction. A 60% higher reduction rate of Cr(VI) by isolated hepatocytes was found during anaerobic in comparison with aerobic conditions.","Microsomal metabolism of hexavalent chromium Inhibitory effect of oxygen and involvement of cytochrome P-450 Abs: The reduction of hexavalent chromium (Cr(VI] by rat liver microsomes was studied. With 15-120 microM Na2CrO4 microsomes (0.5 mg protein/ml) effectively reduced Cr(VI) in the presence of NADPH provided anaerobic conditions. Phenobarbital (PB) and Aroclor 1254 (PCB) pretreatment increased microsomal Cr(VI) reduction while CoCl2 reduced the rate. The rates with 30 microM Na2CrO4 were: 6.4 +/- 0.1, 7.8 +/- 0.7, 13.4 +/- 0.5, 2.95 +/- 0.09 nmol Cr.mg prot.-1 min-1 for control, PB, PCB and cobalt pretreated microsomes respectively. Kinetic studies gave a Michaeli-Menten like first-order kinetics with increases both in Km and Vmax values after pretreatment with PB or PCB. CO partly inhibited the microsomal Cr(VI) reduction. The CO-sensitive reduction rate was directly correlated to the cyt. P-450 content of the different microsomal preparations. Substituting NADH for NADPH gave approximately 27% lower activity with 30 microM Na2CrO4. This activity was neither inducible by cyt. P-450 inducers nor influenced by CO. Oxygen 1.0% and 0.10% gave approximately 100% and 30% inhibition of Cr(VI) reduction (30 microM Na2CrO4) respectively, and an uncompetitive like inhibitory pattern was found. No redox cycling of Cr(VI) was seen. 51Cr binding to the microsomes was approximately 10% after complete reduction of 30 microM Na2CrO4. Externally added FMN, Fe3+-ADP and nitrobenzen stimulated microsomal Cr(VI) reduction. A 60% higher reduction rate of Cr(VI) by isolated hepatocytes was found during anaerobic in comparison with aerobic conditions."
14621,Petrilli and  De Flora 1988,Metabolic reduction of chromium as a threshold mechanism limiting its in vivo activity,"Various mechanisms tend to reduce hexavalent chromium (Cr(VI] in the organism, both outside and inside target cells. A reducing activity has been demonstrated in the blood (mainly in erythrocytes), in secretions of the alimentary tract (saliva, gastric juice) and in the lumen of terminal airways (epithelial-lining fluid and alveolar macrophages). Preparations of several types of cells from various animal species--including human liver, lung parenchyma and bronchial tree cells--are capable of metabolically reducing Cr(VI) to a variable extent. This process can be ascribed to different cytoplasmic components, e.g. to mitochondria, microsomal fractions and especially to cytosolic fractions, where reduction is partly due to electron donors (e.g. glutathione) and mainly to NADPH-dependent enzyme activities, such as DT-diaphorase. Reduction is not only selectively stimulated by enzyme inducers but also, in rat lung cells, by the repeated intra-tracheal administration of Cr(VI) itself. All these reducing reactions are interpreted as detoxifying mechanisms, which constitute a threshold phenomenon in chromium carcinogenesis.","Metabolic reduction of chromium as a threshold mechanism limiting its in vivo activity Abs: Various mechanisms tend to reduce hexavalent chromium (Cr(VI] in the organism, both outside and inside target cells. A reducing activity has been demonstrated in the blood (mainly in erythrocytes), in secretions of the alimentary tract (saliva, gastric juice) and in the lumen of terminal airways (epithelial-lining fluid and alveolar macrophages). Preparations of several types of cells from various animal species--including human liver, lung parenchyma and bronchial tree cells--are capable of metabolically reducing Cr(VI) to a variable extent. This process can be ascribed to different cytoplasmic components, e.g. to mitochondria, microsomal fractions and especially to cytosolic fractions, where reduction is partly due to electron donors (e.g. glutathione) and mainly to NADPH-dependent enzyme activities, such as DT-diaphorase. Reduction is not only selectively stimulated by enzyme inducers but also, in rat lung cells, by the repeated intra-tracheal administration of Cr(VI) itself. All these reducing reactions are interpreted as detoxifying mechanisms, which constitute a threshold phenomenon in chromium carcinogenesis."
14619,Saryan and  Reedy 1988,Chromium determinations in a case of chromic acid ingestion,A fatal case of acute chromic acid ingestion is reported. The case history and biological fluid concentrations of chromium are presented and discussed. Previous cases of acute chromium intoxication are reviewed and recommendations for the management of such patients are presented.,Chromium determinations in a case of chromic acid ingestion Abs: A fatal case of acute chromic acid ingestion is reported. The case history and biological fluid concentrations of chromium are presented and discussed. Previous cases of acute chromium intoxication are reviewed and recommendations for the management of such patients are presented.
14617,Minoia and  Cavalleri 1988,"Chromium in urine, serum and red blood cells in the biological monitoring of workers exposed to different chromium valency states","Using personal air sampling exposure to hexavalent and trivalent chromium was measured in 22 workers mainly exposed to Cr(VI) and in 15 workers mainly exposed to Cr(III) as basic chromium sulphate. Determination of Cr(VI) in the urine of all the subjects using a selective technique by ETA-AAS and liquid anion exchangers failed to show detectable amounts of the hexavalent form, the detection limit of the technique being 0.05 micrograms/L. A clear relationship between exposure and postshift urinary total chromium was found in subjects exposed to Cr(VI), while urinary levels in workers exposed to chromic sulphate high concentration proved lower. Determination of total chromium in serum and red blood cells showed a significant increase of chromium levels in erythrocytes of workers exposed to Cr(VI) while in subjects mainly exposed to Cr(III) an increase of the serum fraction was observed. The results demonstrate that Cr(III) is absorbed through the respiratory tract, but its kinetics and distribution in the body are not the same as for Cr(VI), and are not adequately monitored by short-term urinary determinations. Oxidation states of chromium largely influence uptake, mechanism of absorption, transport and organ distribution as well as toxicity of chromium-containing compounds. In particular, hexavalent derivatives are known to induce adverse effects, both acute and chronic, in occupationally exposed subjects, while there is little conclusive evidence for toxic effects caused by trivalent chromium compounds. Biological monitoring of exposure to chromium(VI) has usually been performed by determining total chromium levels in urine, whereas biological monitoring data in subjects occupationally exposed to Cr(III) are still scanty.(ABSTRACT TRUNCATED AT 250 WORDS)","Chromium in urine, serum and red blood cells in the biological monitoring of workers exposed to different chromium valency states Abs: Using personal air sampling exposure to hexavalent and trivalent chromium was measured in 22 workers mainly exposed to Cr(VI) and in 15 workers mainly exposed to Cr(III) as basic chromium sulphate. Determination of Cr(VI) in the urine of all the subjects using a selective technique by ETA-AAS and liquid anion exchangers failed to show detectable amounts of the hexavalent form, the detection limit of the technique being 0.05 micrograms/L. A clear relationship between exposure and postshift urinary total chromium was found in subjects exposed to Cr(VI), while urinary levels in workers exposed to chromic sulphate high concentration proved lower. Determination of total chromium in serum and red blood cells showed a significant increase of chromium levels in erythrocytes of workers exposed to Cr(VI) while in subjects mainly exposed to Cr(III) an increase of the serum fraction was observed. The results demonstrate that Cr(III) is absorbed through the respiratory tract, but its kinetics and distribution in the body are not the same as for Cr(VI), and are not adequately monitored by short-term urinary determinations. Oxidation states of chromium largely influence uptake, mechanism of absorption, transport and organ distribution as well as toxicity of chromium-containing compounds. In particular, hexavalent derivatives are known to induce adverse effects, both acute and chronic, in occupationally exposed subjects, while there is little conclusive evidence for toxic effects caused by trivalent chromium compounds. Biological monitoring of exposure to chromium(VI) has usually been performed by determining total chromium levels in urine, whereas biological monitoring data in subjects occupationally exposed to Cr(III) are still scanty.(ABSTRACT TRUNCATED AT 250 WORDS)"
14615,Franchini and  Mutti 1988,Selected toxicological aspects of chromium(VI) compounds,,Selected toxicological aspects of chromium(VI) compounds Abs: 
14610,Subramanian 1988,Determination of chromium(III) and chromium(VI) by ammonium pyrrolidinecarbodithioate-methyl isobutyl ketone furnace atomic absorption spectrometry,Biosis copyright: biol abs. rrm water pollution,Determination of chromium(III) and chromium(VI) by ammonium pyrrolidinecarbodithioate-methyl isobutyl ketone furnace atomic absorption spectrometry Abs: Biosis copyright: biol abs. rrm water pollution
14609,Urasa and  Nam 1989,Direct determination of chromium(III) and chromium(VI) with ion chromatography using direct current plasma emission as element-selective detector,"A method for determining trivalent-chromium (16065831) (Cr+3) and hexavalent-chromium (18540299) (Cr+6) by ion chromatography and direct current (DC) plasma atomic emission spectrometry was described. One milliliter (ml) samples of solutions containing chromium(III)-nitrate (13548384) and potassium-chromate (7789006) were injected repeatedly into an ion chromatograph containing an anion or cation exchange column interfaced with the DC plasma sample tube of an atomic emission spectrometer. The multiple injections were used to preconcentrate the samples. When the anion exchange column was used the eluent was 0.05 molar nitric-acid. When the cation exchange column was used 7.5 millimolar (mM) trilithium-citrate and 10.0mM oxalic-acid were used as the eluent. The chromatographic peaks were obtained as analog signals that were monitored by tracing the photomultiplier tube output of the spectrometer at wavelength 425.4 nanometers. The calibration curves for Cr+3 and Cr+6 were linear over the range 0.1 to 100 parts per million (ppm) and nearly identical. The detection limit was below 1.0 part per billion for both Cr+3 and Cr+6 and did not vary with the type of column used. Sodium-chloride at 0 to 1 percent did not affect the Cr+3 signal but increased the Cr+6 signal by a factor of 1.5 to 2. The method was applied to analyzing standard reference samples of human serum and natural water and waste water samples from an industrial process. The reference serum sample contained approximately equal amounts of Cr+3 and Cr+6, 0.06 and 0.05 micrograms per ml (microg/ml), respectively. The reference natural water sample contained only Cr+3, concentration 0.02microg/ml. The waste water samples contained 93.6 to 367.8ppm Cr+6 and 2.6 to 38.7ppm Cr+3. The authors conclude that the scope and applicability of ion chromatography can be extended considerably by using it in conjunction with an element selective detector such as DC plasma atomic spectrometry. It is especially useful for trace metal speciation.","Direct determination of chromium(III) and chromium(VI) with ion chromatography using direct current plasma emission as element-selective detector Abs: A method for determining trivalent-chromium (16065831) (Cr+3) and hexavalent-chromium (18540299) (Cr+6) by ion chromatography and direct current (DC) plasma atomic emission spectrometry was described. One milliliter (ml) samples of solutions containing chromium(III)-nitrate (13548384) and potassium-chromate (7789006) were injected repeatedly into an ion chromatograph containing an anion or cation exchange column interfaced with the DC plasma sample tube of an atomic emission spectrometer. The multiple injections were used to preconcentrate the samples. When the anion exchange column was used the eluent was 0.05 molar nitric-acid. When the cation exchange column was used 7.5 millimolar (mM) trilithium-citrate and 10.0mM oxalic-acid were used as the eluent. The chromatographic peaks were obtained as analog signals that were monitored by tracing the photomultiplier tube output of the spectrometer at wavelength 425.4 nanometers. The calibration curves for Cr+3 and Cr+6 were linear over the range 0.1 to 100 parts per million (ppm) and nearly identical. The detection limit was below 1.0 part per billion for both Cr+3 and Cr+6 and did not vary with the type of column used. Sodium-chloride at 0 to 1 percent did not affect the Cr+3 signal but increased the Cr+6 signal by a factor of 1.5 to 2. The method was applied to analyzing standard reference samples of human serum and natural water and waste water samples from an industrial process. The reference serum sample contained approximately equal amounts of Cr+3 and Cr+6, 0.06 and 0.05 micrograms per ml (microg/ml), respectively. The reference natural water sample contained only Cr+3, concentration 0.02microg/ml. The waste water samples contained 93.6 to 367.8ppm Cr+6 and 2.6 to 38.7ppm Cr+3. The authors conclude that the scope and applicability of ion chromatography can be extended considerably by using it in conjunction with an element selective detector such as DC plasma atomic spectrometry. It is especially useful for trace metal speciation."
14602,Rossi et al. 1988,Mitochondrial reduction of the carcinogen chromate: formation of chromium (V),"Incubation of chromate with isolated rat liver mitochondria in vitro resulted in the uptake and reduction of chromium(VI), as well as the formation of chromium(V) species. Chromate was rapidly taken up and reduced by intact mitochondria. The rate of reduction of chromate by intact mitochondria was increased upon addition of succinate or malate plus glutamate, substrates for the electron-transport chain, but was decreased upon addition of cyanide, an inhibitor of the electron-transport chain. Incubation of chromate with mitochondria in the presence or absence of malate, glutamate, and succinate resulted in a steady increase in the level of chromium(V) over time. The extent of chromium(V) formation was increased upon addition of malate, glutamate, and succinate but was inhibited upon addition of the electron-transport chain inhibitors, antimycin, cyanide, or rotenone, to whole mitochondria. High levels of glutamate plus malate inhibited chromium(V) formation; however, high concentrations of succinate or sulfate had no effect. These studies suggest that the chromate-reductase activity in mitochondria is due to the electron-transport chain as well as other mitochondrial reducing systems which are insensitive to inhibitors of the electron-transport chain. Since chromium(VI) is effectively metabolized by mitochondria in vitro and chromium(V) ""reactive intermediates"" are formed in the process, mitochondria may play a role in chromium(VI) carcinogenesis.","Mitochondrial reduction of the carcinogen chromate: formation of chromium (V) Abs: Incubation of chromate with isolated rat liver mitochondria in vitro resulted in the uptake and reduction of chromium(VI), as well as the formation of chromium(V) species. Chromate was rapidly taken up and reduced by intact mitochondria. The rate of reduction of chromate by intact mitochondria was increased upon addition of succinate or malate plus glutamate, substrates for the electron-transport chain, but was decreased upon addition of cyanide, an inhibitor of the electron-transport chain. Incubation of chromate with mitochondria in the presence or absence of malate, glutamate, and succinate resulted in a steady increase in the level of chromium(V) over time. The extent of chromium(V) formation was increased upon addition of malate, glutamate, and succinate but was inhibited upon addition of the electron-transport chain inhibitors, antimycin, cyanide, or rotenone, to whole mitochondria. High levels of glutamate plus malate inhibited chromium(V) formation; however, high concentrations of succinate or sulfate had no effect. These studies suggest that the chromate-reductase activity in mitochondria is due to the electron-transport chain as well as other mitochondrial reducing systems which are insensitive to inhibitors of the electron-transport chain. Since chromium(VI) is effectively metabolized by mitochondria in vitro and chromium(V) ""reactive intermediates"" are formed in the process, mitochondria may play a role in chromium(VI) carcinogenesis."
14601,Suzuki 1988,Reduction of hexavalent chromium by ascorbic acid in rat lung lavage fluid,"The reduction of hexavalent chromium [chromium(VI)] in lung lavage fluids, microsomal (S-9) fractions of lung and liver tissues, erythrocyte lysates and plasma prepared from adult rats was examined at pH 7.4 (37 degrees C). Specific reducing capacity, which was defined as the amount of chromium(VI) reduced per mg of protein in the test sample, was highest in the lavage fluids. The concomitant trivalent species [chromium(III)] was detected as complexes with some of the lavage components and probably as colloidal hydroxides. By gel filtration analysis and UV spectrometry, ascorbic acid (AsA) was identified as an important reducing factor in the lavage fluids. AsA levels in the lavage fluids were about 38 micrograms/g tissue, corresponding to 12% of total AsA in the intact lungs. The molar ratios of oxidized AsA and reduced chromium(VI) in the lavage samples were about 3:2.3 on an average. On the basis of this molar ratio, the AsA levels in the lavage fluids are equivalent to a reducing capacity of 8.4 micrograms chromium(VI)/g tissue. These results suggest that the lining layers (surfactant layers) of rat lungs provide an AsA-related capacity for protection of the cells against the toxic effects of chromates and probably other oxidants.","Reduction of hexavalent chromium by ascorbic acid in rat lung lavage fluid Abs: The reduction of hexavalent chromium [chromium(VI)] in lung lavage fluids, microsomal (S-9) fractions of lung and liver tissues, erythrocyte lysates and plasma prepared from adult rats was examined at pH 7.4 (37 degrees C). Specific reducing capacity, which was defined as the amount of chromium(VI) reduced per mg of protein in the test sample, was highest in the lavage fluids. The concomitant trivalent species [chromium(III)] was detected as complexes with some of the lavage components and probably as colloidal hydroxides. By gel filtration analysis and UV spectrometry, ascorbic acid (AsA) was identified as an important reducing factor in the lavage fluids. AsA levels in the lavage fluids were about 38 micrograms/g tissue, corresponding to 12% of total AsA in the intact lungs. The molar ratios of oxidized AsA and reduced chromium(VI) in the lavage samples were about 3:2.3 on an average. On the basis of this molar ratio, the AsA levels in the lavage fluids are equivalent to a reducing capacity of 8.4 micrograms chromium(VI)/g tissue. These results suggest that the lining layers (surfactant layers) of rat lungs provide an AsA-related capacity for protection of the cells against the toxic effects of chromates and probably other oxidants."
14600,Suzuki and  Fukuda 1989,Anion-exchange high-performance liquid chromatographic determination of ascorbic acid and hexavalent chromium in rat lung preparations after treatment with sodium chromate in vitro and in vivo,"Simultaneous analysis of ascorbic acid and chromium (VI) in soluble fractions and bronchoalveolar lavage fluids of rat lungs treated with sodium chromate in vitro and in vivo was performed by anion-exchange high-performance liquid chromatography coupled to a photodiode-array detector. Absorbances at 265 and 370 nm were used for the determination of ascorbic acid and chromium (VI), respectively. The calibration graphs of standard solutions were linear in the test ranges of ascorbic acid an chromium (VI) (below 10 and 8 ppm, respectively). The detection limits of ascorbic acid and chromium (VI) were 1 and 0.5 ng, respectively. The recovery of ascorbic acid from lung tissues homogenized at pH 7.4 was 99%, and that of chromium (VI) was 96%, when tissues were homogenized under alkaline conditions (pH 11.4). Using this method, ascorbic acid levels in the soluble fractions and lavage fluids of normal rat lungs were determined. In the lung of a rat intratracheally injected with a saline solution of sodium chromate, ascorbic acid decreased to 80% of the normal level, and ca. 90% of the chromium (VI) was reduced within 4 min after injection, indicating that the ascorbic acid-related reduction of chromium (VI) is very rapid. The present method will be useful for studies of the reduction of chromium (VI) by ascorbic acid in biological systems.","Anion-exchange high-performance liquid chromatographic determination of ascorbic acid and hexavalent chromium in rat lung preparations after treatment with sodium chromate in vitro and in vivo Abs: Simultaneous analysis of ascorbic acid and chromium (VI) in soluble fractions and bronchoalveolar lavage fluids of rat lungs treated with sodium chromate in vitro and in vivo was performed by anion-exchange high-performance liquid chromatography coupled to a photodiode-array detector. Absorbances at 265 and 370 nm were used for the determination of ascorbic acid and chromium (VI), respectively. The calibration graphs of standard solutions were linear in the test ranges of ascorbic acid an chromium (VI) (below 10 and 8 ppm, respectively). The detection limits of ascorbic acid and chromium (VI) were 1 and 0.5 ng, respectively. The recovery of ascorbic acid from lung tissues homogenized at pH 7.4 was 99%, and that of chromium (VI) was 96%, when tissues were homogenized under alkaline conditions (pH 11.4). Using this method, ascorbic acid levels in the soluble fractions and lavage fluids of normal rat lungs were determined. In the lung of a rat intratracheally injected with a saline solution of sodium chromate, ascorbic acid decreased to 80% of the normal level, and ca. 90% of the chromium (VI) was reduced within 4 min after injection, indicating that the ascorbic acid-related reduction of chromium (VI) is very rapid. The present method will be useful for studies of the reduction of chromium (VI) by ascorbic acid in biological systems."
14597,Wiegand et al. 1984,The reduction of chromium (VI) to chromium (III) by glutathione: An intracellular redox pathway in the metabolism of the carcinogen chromate,"The capacity of glutathione (GSH) to reduce Cr(VI) to Cr(III) in vitro was investigated. The reaction was determined spectrophotometrically by following the absorption of Cr(VI) at 370 nm. At stoichiometric conditions (molar ratio Cr(VI)/GSH of 1:3) the reduction was strongly dependent on the solution's pH. It was much slower at pH 7.4 than at pH values below 5. An excess of GSH (100- or 1000-fold) accelerated the reaction. In any case, 3 GSH molecules were required to reduce 1 molecule of chromate. Incubation of human red blood cells (RBC) with an excess of Na2CrO4 (10 mM) decreased the GSH content of the cells to 10% of the original amount. This depletion of GSH was similar to that obtained when RBC were incubated with 62 mM diethylmaleate (DEM), a well known GSH depleting agent. Sephadex G-100 chromatography of lysates from human RBC incubated with radioactive chromate (51Cr(VI] showed a strong affinity of 51Cr for hemoglobin: 97% of the applied dose was bound to hemoglobin whilst only minor amounts of 51Cr were found in the low-molecular fractions. However, incubations of prepared lysates (as opposed to intact cells) with 10 mM Na2 51CrO4 markedly raised the chromium content of low-molecular fractions (probably GSH-Cr-complexes), probably indicative of a role of GSH in the intra-cellular reduction of Cr(VI) to Cr(III), the latter being regarded as the ultimately toxic species of this metal.","The reduction of chromium (VI) to chromium (III) by glutathione: An intracellular redox pathway in the metabolism of the carcinogen chromate Abs: The capacity of glutathione (GSH) to reduce Cr(VI) to Cr(III) in vitro was investigated. The reaction was determined spectrophotometrically by following the absorption of Cr(VI) at 370 nm. At stoichiometric conditions (molar ratio Cr(VI)/GSH of 1:3) the reduction was strongly dependent on the solution's pH. It was much slower at pH 7.4 than at pH values below 5. An excess of GSH (100- or 1000-fold) accelerated the reaction. In any case, 3 GSH molecules were required to reduce 1 molecule of chromate. Incubation of human red blood cells (RBC) with an excess of Na2CrO4 (10 mM) decreased the GSH content of the cells to 10% of the original amount. This depletion of GSH was similar to that obtained when RBC were incubated with 62 mM diethylmaleate (DEM), a well known GSH depleting agent. Sephadex G-100 chromatography of lysates from human RBC incubated with radioactive chromate (51Cr(VI] showed a strong affinity of 51Cr for hemoglobin: 97% of the applied dose was bound to hemoglobin whilst only minor amounts of 51Cr were found in the low-molecular fractions. However, incubations of prepared lysates (as opposed to intact cells) with 10 mM Na2 51CrO4 markedly raised the chromium content of low-molecular fractions (probably GSH-Cr-complexes), probably indicative of a role of GSH in the intra-cellular reduction of Cr(VI) to Cr(III), the latter being regarded as the ultimately toxic species of this metal."
14590,Verschoor et al. 1988,Renal function of chrome-plating workers and welders,"The influence of occupational exposure to water-soluble chromium (VI) on renal function was examined. In male chrome-plating workers (n = 29), stainless steel welders (n = 45), boilermakers (n = 18) and a control group of workers (n = 71), the level of chromium in the urine (Cr-U), the chromium clearance, and sensitive renal function parameters were determined. The glomerular-function parameters of the chrome-plating workers (Cr-U 1 to 34 micrograms/g creat) and welders (Cr-U 1 to 62 micrograms/g creatine) appeared to differ from those of the boilermakers (Cr-U 0.3 to 1.5 micrograms/g creatine) and controls (Cr-U 0.1 to 2 micrograms/g creatine). The renal function parameters were not related to chromium concentration in the urine or to chromium clearance.","Renal function of chrome-plating workers and welders Abs: The influence of occupational exposure to water-soluble chromium (VI) on renal function was examined. In male chrome-plating workers (n = 29), stainless steel welders (n = 45), boilermakers (n = 18) and a control group of workers (n = 71), the level of chromium in the urine (Cr-U), the chromium clearance, and sensitive renal function parameters were determined. The glomerular-function parameters of the chrome-plating workers (Cr-U 1 to 34 micrograms/g creat) and welders (Cr-U 1 to 62 micrograms/g creatine) appeared to differ from those of the boilermakers (Cr-U 0.3 to 1.5 micrograms/g creatine) and controls (Cr-U 0.1 to 2 micrograms/g creatine). The renal function parameters were not related to chromium concentration in the urine or to chromium clearance."
14556,Laborda et al. 1986,Nephrotoxic and hepatotoxic effects of chromium compounds in rats,,Nephrotoxic and hepatotoxic effects of chromium compounds in rats Abs: 
14543,Arslan et al. 1987,Intracellular chromium reduction,"Two steps are involved in the uptake of Cr(VI): (1) the diffusion of the anion CrO4(2-) through a facilitated transport system, presumably the non-specific anion carrier and (2) the intracellular reduction of Cr(VI) to Cr(III). The intracellular reduction of Cr(VI), keeping the cytoplasmic concentration of Cr(VI) low, facilitates accumulation of chromate from extracellular medium into the cell. In the present paper, a direct demonstration of intracellular chromium reduction is provided by means of electron paramagnetic (spin) resonance (EPR) spectroscopy. Incubation of metabolically active rat thymocytes with chromate originates a signal which can be attributed to a paramagnetic species of chromium, Cr(V) or Cr(III). The EPR signal is originated by intracellular reduction of chromium since: (1) it is observed only when cells are incubated with chromate, (2) it is present even after extensive washings of the cells in a chromium-free medium; (3) it is abolished when cells are incubated with drugs able to reduce the glutathione pool, i.e., diethylmaleate or phorone; and (4) it is abolished when cells are incubated in the presence of a specific inhibitor of the anion carrier, 4-acetamido-4'-isothiocyanatostilbene-2-2'-disulfonic acid.","Intracellular chromium reduction Abs: Two steps are involved in the uptake of Cr(VI): (1) the diffusion of the anion CrO4(2-) through a facilitated transport system, presumably the non-specific anion carrier and (2) the intracellular reduction of Cr(VI) to Cr(III). The intracellular reduction of Cr(VI), keeping the cytoplasmic concentration of Cr(VI) low, facilitates accumulation of chromate from extracellular medium into the cell. In the present paper, a direct demonstration of intracellular chromium reduction is provided by means of electron paramagnetic (spin) resonance (EPR) spectroscopy. Incubation of metabolically active rat thymocytes with chromate originates a signal which can be attributed to a paramagnetic species of chromium, Cr(V) or Cr(III). The EPR signal is originated by intracellular reduction of chromium since: (1) it is observed only when cells are incubated with chromate, (2) it is present even after extensive washings of the cells in a chromium-free medium; (3) it is abolished when cells are incubated with drugs able to reduce the glutathione pool, i.e., diethylmaleate or phorone; and (4) it is abolished when cells are incubated in the presence of a specific inhibitor of the anion carrier, 4-acetamido-4'-isothiocyanatostilbene-2-2'-disulfonic acid."
14542,Angerer et al. 1987,Occupational chronic exposure to metals I Chromium exposure of stainless steel welders - biological monitoring,"Occupational exposure to chromium (7440473) among stainless steel welders was evaluated through environmental and biological sampling. Blood and urine samples obtained from 103 male welders, aged 20 to 55 years, who performed manual metal arc welding (MMA), metal inert gas welding (MIG), or both were analyzed for chromium levels in erythrocytes, plasma and urine. Airborne concentrations of hexavalent chromium compounds in the breathing zone of the welders were determined by personal air monitoring. Concentrations of chromium-trioxide (1333820) detected in the breathing zone during MMA ranged from less than 1 to 50 micrograms per cubic meter (microg/m3), with a median of 4microg/m3. Air concentrations of chromium-trioxide during MIG were slightly higher, ranging from less than 1 to 80microg/m3, with a median of 10microg/m3. The mean concentrations of chromium in erythrocytes were 1.18, 1.44 and 2.51 micrograms per liter (microg/l) in welders performing MMA, MIG, or both, respectively. Mean plasma levels of chromium were significantly higher among the MIG welders and welders performing both MMA and MIG welding, with values of 14.70 and 13.56microg/l, than among MMA welders in which the mean value was 9.00microg/l. The highest plasma chromium level among the welders, 68.5microg/l, was 50 times greater than that of the general population. Urinary chromium levels among the welders ranged from 5.40 to 229.4microg/l, and were 5 to 200 times higher than average levels in unexposed persons. Levels of chromium in erythrocytes, plasma and urine were highly significantly correlated. The authors conclude that simultaneous determination of chromium levels in plasma and erythrocytes provides the best method for biological monitoring of chromium exposure.","Occupational chronic exposure to metals I Chromium exposure of stainless steel welders - biological monitoring Abs: Occupational exposure to chromium (7440473) among stainless steel welders was evaluated through environmental and biological sampling. Blood and urine samples obtained from 103 male welders, aged 20 to 55 years, who performed manual metal arc welding (MMA), metal inert gas welding (MIG), or both were analyzed for chromium levels in erythrocytes, plasma and urine. Airborne concentrations of hexavalent chromium compounds in the breathing zone of the welders were determined by personal air monitoring. Concentrations of chromium-trioxide (1333820) detected in the breathing zone during MMA ranged from less than 1 to 50 micrograms per cubic meter (microg/m3), with a median of 4microg/m3. Air concentrations of chromium-trioxide during MIG were slightly higher, ranging from less than 1 to 80microg/m3, with a median of 10microg/m3. The mean concentrations of chromium in erythrocytes were 1.18, 1.44 and 2.51 micrograms per liter (microg/l) in welders performing MMA, MIG, or both, respectively. Mean plasma levels of chromium were significantly higher among the MIG welders and welders performing both MMA and MIG welding, with values of 14.70 and 13.56microg/l, than among MMA welders in which the mean value was 9.00microg/l. The highest plasma chromium level among the welders, 68.5microg/l, was 50 times greater than that of the general population. Urinary chromium levels among the welders ranged from 5.40 to 229.4microg/l, and were 5 to 200 times higher than average levels in unexposed persons. Levels of chromium in erythrocytes, plasma and urine were highly significantly correlated. The authors conclude that simultaneous determination of chromium levels in plasma and erythrocytes provides the best method for biological monitoring of chromium exposure."
14521,Petrilli et al. 1986,Metabolic reduction of chromium by alveolar macrophages and its relationships to cigarette smoke,"Pulmonary alveolar macrophages (PAM), obtained by bronchoalveolar lavage from 47 individuals, reduced hexavalent chromium [Cr(VI)] and decreased its mutagenicity. Their specific activity--mostly mediated by cytosolic, enzyme-catalyzed mechanisms--was significantly higher than in corresponding preparations of mixed-cell populations from human peripheral lung parenchyma or bronchial tree, or from rat lung or liver. At equivalent number of PAM, Cr(VI) reduction, total protein, and some oxidoreductase activities were significantly increased in smokers. No appreciable variation could be detected between lung cancer and noncancer patients. In rats, the Cr(VI)-reducing activity of PAM preparations was induced by Aroclor 1254. Thus, alveolar macrophages provide crucial defense mechanisms not only by phagocytizing metals, but also by metabolically reducing Cr(VI). The epithelial-lining fluid (ELF) also displayed some Cr(VI) reduction. Together with already investigated metabolic processes occurring inside lung cells, these mechanisms are expected to determine thresholds in the pulmonary carcinogenicity of chromium.","Metabolic reduction of chromium by alveolar macrophages and its relationships to cigarette smoke Abs: Pulmonary alveolar macrophages (PAM), obtained by bronchoalveolar lavage from 47 individuals, reduced hexavalent chromium [Cr(VI)] and decreased its mutagenicity. Their specific activity--mostly mediated by cytosolic, enzyme-catalyzed mechanisms--was significantly higher than in corresponding preparations of mixed-cell populations from human peripheral lung parenchyma or bronchial tree, or from rat lung or liver. At equivalent number of PAM, Cr(VI) reduction, total protein, and some oxidoreductase activities were significantly increased in smokers. No appreciable variation could be detected between lung cancer and noncancer patients. In rats, the Cr(VI)-reducing activity of PAM preparations was induced by Aroclor 1254. Thus, alveolar macrophages provide crucial defense mechanisms not only by phagocytizing metals, but also by metabolically reducing Cr(VI). The epithelial-lining fluid (ELF) also displayed some Cr(VI) reduction. Together with already investigated metabolic processes occurring inside lung cells, these mechanisms are expected to determine thresholds in the pulmonary carcinogenicity of chromium."
14511,Partington 1950,Acute poisoning with potassium bichromate,,Acute poisoning with potassium bichromate Abs: 
14510,Parkhurst 1925,Dermatosis industrialis in a blue print worker due to chromium compounds,"Three case studies of workers in blue print plants who developed skin eruption due to chromium (7440473) compounds. Investigation revealed that erythematovesicular and small papular dermatitis may result from contact of potassium-bichromate (7778509) with the skin in susceptible persons, and that this may be avoided by rinsing frequently with a saturated solution of sodium-bisulfite (7631905), and then with water.","Dermatosis industrialis in a blue print worker due to chromium compounds Abs: Three case studies of workers in blue print plants who developed skin eruption due to chromium (7440473) compounds. Investigation revealed that erythematovesicular and small papular dermatitis may result from contact of potassium-bichromate (7778509) with the skin in susceptible persons, and that this may be avoided by rinsing frequently with a saturated solution of sodium-bisulfite (7631905), and then with water."
14493,Newbold et al. 1979,"The cytotoxic, mutagenic and clastogenic effects of chromium-containing compounds on mammalian cells in culture","Examples of chromic and chromate salts have been examined for their effects on a cultured Chinese hamster cell line. The responses studied were cytotoxicity, mutagenesis and clastogenesis. Chromate (hexavalent chromium) salts of both high and medium water solubility were active in producing all three classes of response, whereas an insoluble chromate salt and a soluble chromic (trivalent chromium) salt were inactive. In addition to illustrating the value of using mammalian cells in culture for screening chemicals for biological activity, the results of this study reinforce current views regarding the genotoxic properties of chromates.","The cytotoxic, mutagenic and clastogenic effects of chromium-containing compounds on mammalian cells in culture Abs: Examples of chromic and chromate salts have been examined for their effects on a cultured Chinese hamster cell line. The responses studied were cytotoxicity, mutagenesis and clastogenesis. Chromate (hexavalent chromium) salts of both high and medium water solubility were active in producing all three classes of response, whereas an insoluble chromate salt and a soluble chromic (trivalent chromium) salt were inactive. In addition to illustrating the value of using mammalian cells in culture for screening chemicals for biological activity, the results of this study reinforce current views regarding the genotoxic properties of chromates."
14468,Mathur et al. 1977,Comparative toxicity of trivalent and hexavalent chromium to rabbits II Morphological changes in some organs,"Toxicity of trivalent and hexavalent chromium compounds was investigated in experimental rabbits to ascertain health hazards among industrial workers of miners occupationally exposed to such chemicals. Brain, kidney and myocardium showed a tendency to accumulate chromium irrespective of its valency state; the morphological changes were more marked in animals exposed to hexavalent chromium. However, no definite co-relation could be observed between the concentration of the metal and the degree of histological changes in these organs.","Comparative toxicity of trivalent and hexavalent chromium to rabbits II Morphological changes in some organs Abs: Toxicity of trivalent and hexavalent chromium compounds was investigated in experimental rabbits to ascertain health hazards among industrial workers of miners occupationally exposed to such chemicals. Brain, kidney and myocardium showed a tendency to accumulate chromium irrespective of its valency state; the morphological changes were more marked in animals exposed to hexavalent chromium. However, no definite co-relation could be observed between the concentration of the metal and the degree of histological changes in these organs."
14460,MacKenzie et al. 1958,Chronic toxicity studies. II. Hexavalent and trivalent chromium administered in drinking water to rats,,Chronic toxicity studies. II. Hexavalent and trivalent chromium administered in drinking water to rats Abs: 
14453,Löfroth 1978,The mutagenicity of hexavalent chromium is decreased by microsomal metabolism,,The mutagenicity of hexavalent chromium is decreased by microsomal metabolism Abs: 
14449,Levy and  Venitt 1975,Carcinogenic and mutagenic activity of chromium containing materials,,Carcinogenic and mutagenic activity of chromium containing materials Abs: 
14448,Levis et al. 1978,Effects of potassium dichromate on nucleic acid and protein syntheses and on precursor uptake in BHK fibroblasts,"Treatments for 1 to 4 hr with 10-4 M potassium dichromate, a soluble hexavalent chromium salt with a strong oxidizing power, markedly reduce DNA and RNA accumulation rates in hamster fibroblasts grown in vitro (BHK line), as shown by quantitative spectrophotometric determinations. Such inhibitory action is not immediately evident on the basis of the incorporation rates of labeled nucleosides into DNA and RNA, as dichromate affects also the relative concentrations of labeled precursors in the intracellular pool. Cichromate first stimulates and then inhibits nucleoside (mostly thymidine) uptake, whereas amino acid uptake is immediately inhibited. Actual rates of macromolecular syntheses have been calculated by taking into account the induced changes of soluble precursor concentrations; such normalized rates point out that dichromate induces a sudden blockage of DNA replication, whereas RNA and protein syntheses are secondarily inhibited. The observed cytotoxic effects of dichromate are tentatively referred to the oxidation of cell components by hexavalent chromium and thereby to the interaction of reduced trivalent chromium with specific biological ligands on cell membrane and on DNA.","Effects of potassium dichromate on nucleic acid and protein syntheses and on precursor uptake in BHK fibroblasts Abs: Treatments for 1 to 4 hr with 10-4 M potassium dichromate, a soluble hexavalent chromium salt with a strong oxidizing power, markedly reduce DNA and RNA accumulation rates in hamster fibroblasts grown in vitro (BHK line), as shown by quantitative spectrophotometric determinations. Such inhibitory action is not immediately evident on the basis of the incorporation rates of labeled nucleosides into DNA and RNA, as dichromate affects also the relative concentrations of labeled precursors in the intracellular pool. Cichromate first stimulates and then inhibits nucleoside (mostly thymidine) uptake, whereas amino acid uptake is immediately inhibited. Actual rates of macromolecular syntheses have been calculated by taking into account the induced changes of soluble precursor concentrations; such normalized rates point out that dichromate induces a sudden blockage of DNA replication, whereas RNA and protein syntheses are secondarily inhibited. The observed cytotoxic effects of dichromate are tentatively referred to the oxidation of cell components by hexavalent chromium and thereby to the interaction of reduced trivalent chromium with specific biological ligands on cell membrane and on DNA."
14447,Levis and  Majone 1979,Cytotoxic and clastogenic effects of soluble chromium compounds on mammalian cell cultures,"HEEP COPYRIGHT: BIOL ABS. The inhibition of cell growth, the reduction of cell survival and the induction of chromosome aberrations and of sister chromatid exchange (SCE) were determined in cultured hamster cell lines (fibroblast BHK and ovary CHO) treated with 11 water-soluble compounds of hexavalent and trivalent chromium (a suspected human carcinogen). All Cr6+ compounds inhibit growth of BHK cells and reduce survival of CHO cells to levels comparable to those obtained only after exposure to 100-1000 times higher Cr3+ concentrations. The cytotoxicity curves obtained with the different Cr6+ compounds are almost overlapping, whereas marked differences of activity are noticeable among Cr3+ compounds. Giant cells are obtained after exposure to Cr6+ and Cr3+ compounds, as shown by the rise of DNA and RNA per cell, and are due to the blockage of the cell cycle without sudden inhibition of macromolecular syntheses. Both Cr6+ and Cr3+ compounds are able to induce chromosome aberrations, whereas Cr3+ is absolutely incapable of inducing SCE, only Cr6+ being active. The frequency of chromosome aberrations is increased about 10-fold after exposure to 1.0 mug/ml Cr6+, whereas it is only doubled after treatment with up to 150 mug/ml Cr3+. In spite of the sensitivity of CHO cells to the induction of SCE by mitomycin C, the frequency of SCE hardly doubles after exposure to Cr6+ compounds. The present data confirm that Cr6+ compounds are characterized by a marked cytotoxicity and clastogenic action on mammalian cell cultures and show that Cr3+ compounds, though cytotoxic only at extremely high concentrations and not increasing the frequency of SCE, are not completely without cytogenetic effect, as they are able to induce chromosome aberrations.","Cytotoxic and clastogenic effects of soluble chromium compounds on mammalian cell cultures Abs: HEEP COPYRIGHT: BIOL ABS. The inhibition of cell growth, the reduction of cell survival and the induction of chromosome aberrations and of sister chromatid exchange (SCE) were determined in cultured hamster cell lines (fibroblast BHK and ovary CHO) treated with 11 water-soluble compounds of hexavalent and trivalent chromium (a suspected human carcinogen). All Cr6+ compounds inhibit growth of BHK cells and reduce survival of CHO cells to levels comparable to those obtained only after exposure to 100-1000 times higher Cr3+ concentrations. The cytotoxicity curves obtained with the different Cr6+ compounds are almost overlapping, whereas marked differences of activity are noticeable among Cr3+ compounds. Giant cells are obtained after exposure to Cr6+ and Cr3+ compounds, as shown by the rise of DNA and RNA per cell, and are due to the blockage of the cell cycle without sudden inhibition of macromolecular syntheses. Both Cr6+ and Cr3+ compounds are able to induce chromosome aberrations, whereas Cr3+ is absolutely incapable of inducing SCE, only Cr6+ being active. The frequency of chromosome aberrations is increased about 10-fold after exposure to 1.0 mug/ml Cr6+, whereas it is only doubled after treatment with up to 150 mug/ml Cr3+. In spite of the sensitivity of CHO cells to the induction of SCE by mitomycin C, the frequency of SCE hardly doubles after exposure to Cr6+ compounds. The present data confirm that Cr6+ compounds are characterized by a marked cytotoxicity and clastogenic action on mammalian cell cultures and show that Cr3+ compounds, though cytotoxic only at extremely high concentrations and not increasing the frequency of SCE, are not completely without cytogenetic effect, as they are able to induce chromosome aberrations."
14442,Leonard and  Lauwerys 1980,Carcinogenicity and mutagenicity of chromium,"Occupational exposure represents the main source of human contamination by chromium. For non-occupationally exposed people the major environmental exposure to chromium occurs as a consequence of its presence in food. Chromium must be considered as an essential element. Its deficiency impairs glucose metabolism. Trivalent chromium salts are poorly absorbed through the gastro-intestinal and respiratory tracts because they do not cross membranes easily. Hexavalent chromium can be absorbed by the oral and pulmonary routes and probably also through the skin. After its absorption, hexavalent chromium is rapidly reduced to the trivalent form which is probably the only form to be found in biological material. Epidemiological studies have shown that some chromium salts (mainly the slightly soluble hexavalent salts) are carcinogens. Lung cancers have, indeed, often been reported among workers in chromate-producing industry and, to a lesser extent, in workers from the chrome-pigment industry. The first attempts to produce cancers in experimental animals by inhalation or parenteral introduction gave negative or equivocal results but, from 1960, positive results have been obtained with various chromium compounds. As for the carcinogenic activity, the mutagenicity of chromium has mainly been found with hexavalent salts. In the majority of assay systems used, trivalent chromium appears inactive. It can be considered as evident, however, that the ultimate mutagen which binds to the genetic material is the trivalent form produced intracellularly from hexavalent chromium, the apparent lack of activity of the trivalent form being due to its poor cellular uptake.","Carcinogenicity and mutagenicity of chromium Abs: Occupational exposure represents the main source of human contamination by chromium. For non-occupationally exposed people the major environmental exposure to chromium occurs as a consequence of its presence in food. Chromium must be considered as an essential element. Its deficiency impairs glucose metabolism. Trivalent chromium salts are poorly absorbed through the gastro-intestinal and respiratory tracts because they do not cross membranes easily. Hexavalent chromium can be absorbed by the oral and pulmonary routes and probably also through the skin. After its absorption, hexavalent chromium is rapidly reduced to the trivalent form which is probably the only form to be found in biological material. Epidemiological studies have shown that some chromium salts (mainly the slightly soluble hexavalent salts) are carcinogens. Lung cancers have, indeed, often been reported among workers in chromate-producing industry and, to a lesser extent, in workers from the chrome-pigment industry. The first attempts to produce cancers in experimental animals by inhalation or parenteral introduction gave negative or equivocal results but, from 1960, positive results have been obtained with various chromium compounds. As for the carcinogenic activity, the mutagenicity of chromium has mainly been found with hexavalent salts. In the majority of assay systems used, trivalent chromium appears inactive. It can be considered as evident, however, that the ultimate mutagen which binds to the genetic material is the trivalent form produced intracellularly from hexavalent chromium, the apparent lack of activity of the trivalent form being due to its poor cellular uptake."
14436,Kuschner and  Laskin 1972,Studies in pulmonary carcinogenesis,,Studies in pulmonary carcinogenesis Abs: 
14432,Langard and  Norseth 1975,A cohort study of bronchial carcinomas in workers producing chromate pigments,"A cohort study of the incidence of bronchial cancer in male workers in a small company producing chromate pigments is presented. Altogether 133 workers had been employed by the company from the time production was started in 1948 until the end of 1972. Workers with more than three years employment were included in the study, and three cases of bronchial carcinoma were found among the 24 workers who fulfilled this requirement. Based on the data of the Cancer Registry of Norway the risk of bronchial cancer for a corresponding group of the general population was found to be 0.079, which gives a risk ratio for exposed workers of approximately 38. The average age of the cancer patients was as low as 50 years at the time of diagnosis. All workers in the company had been exposed mainly to zinc chromate dust, and the exposure levels of the workers developing bronchial cancers had probably been from 0-5 to 1-5 mg Cr/m-3 for six to nine years. Two of the three patients were smokers. It is assumed that exposure to chromate pigments, and probably to zinc chromate, may be related to the increased incidence of bronchial cancer in this group of workers. The possibility of a contributing effect of tobacco smoking in at least two of the three cases cannot be ruled out.","A cohort study of bronchial carcinomas in workers producing chromate pigments Abs: A cohort study of the incidence of bronchial cancer in male workers in a small company producing chromate pigments is presented. Altogether 133 workers had been employed by the company from the time production was started in 1948 until the end of 1972. Workers with more than three years employment were included in the study, and three cases of bronchial carcinoma were found among the 24 workers who fulfilled this requirement. Based on the data of the Cancer Registry of Norway the risk of bronchial cancer for a corresponding group of the general population was found to be 0.079, which gives a risk ratio for exposed workers of approximately 38. The average age of the cancer patients was as low as 50 years at the time of diagnosis. All workers in the company had been exposed mainly to zinc chromate dust, and the exposure levels of the workers developing bronchial cancers had probably been from 0-5 to 1-5 mg Cr/m-3 for six to nine years. Two of the three patients were smokers. It is assumed that exposure to chromate pigments, and probably to zinc chromate, may be related to the increased incidence of bronchial cancer in this group of workers. The possibility of a contributing effect of tobacco smoking in at least two of the three cases cannot be ruled out."
14420,Kitagawa et al. 1982,Uptake of hexavalent chromium by bovine erythrocytes and its interaction with cytoplasmic components; the role of glutathione,"Hexavalent chromium (Cr(VI)) anion gradually penetrated into bovine erythrocytes and bound with cytoplasmic components. Its penetration was strongly inhibited by the NH2-reactive agent, 4-acetamido-4'-isothiocyano-stilbene-2,2'-disulfonic acid (SITS) and the SH-reactive agent, N-ethylmaleimide (NEM). Gel filtration showed that the intracellular component that bound to chromium was hemoglobin. The binding affinity of Cr(VI) to hemoglobin in the absence of glutathione in vitro was found to be much less than in intact erythrocytes. However, in the presence of glutathione, the binding affinity of Cr(VI) to hemoglobin became much higher. This indicates that reduction of hemoglobin or Cr(VI) by glutathione is involved in the binding. Cr(VI) interacted only weakly with the membrane and did not cause hemolysis of bovine erythrocytes, unlike heavy metals such as Hg2+.","Uptake of hexavalent chromium by bovine erythrocytes and its interaction with cytoplasmic components; the role of glutathione Abs: Hexavalent chromium (Cr(VI)) anion gradually penetrated into bovine erythrocytes and bound with cytoplasmic components. Its penetration was strongly inhibited by the NH2-reactive agent, 4-acetamido-4'-isothiocyano-stilbene-2,2'-disulfonic acid (SITS) and the SH-reactive agent, N-ethylmaleimide (NEM). Gel filtration showed that the intracellular component that bound to chromium was hemoglobin. The binding affinity of Cr(VI) to hemoglobin in the absence of glutathione in vitro was found to be much less than in intact erythrocytes. However, in the presence of glutathione, the binding affinity of Cr(VI) to hemoglobin became much higher. This indicates that reduction of hemoglobin or Cr(VI) by glutathione is involved in the binding. Cr(VI) interacted only weakly with the membrane and did not cause hemolysis of bovine erythrocytes, unlike heavy metals such as Hg2+."
14417,Kaaber and  Veien 1977,The significance of chromate ingestion in patients allergic to chromate,"A double-blind study was carried out to demonstrate the significance of chromate ingestion in the persistence of chromic chromate dermatitis. Each of 31 chromate-allergic patients was given one tablet containing 7.1 mg potassium dichromate, plus a placebo tablet. The dermatitis of 11 of the 31 patients flared after the ingestion of chromate, but not after placebo. 3 patients had equivocal reactions to both tablets; the dermatitis worsened in 2 patients following ingestion of the placebo but not after the chromate tablet. No statistically significant difference could be found between reactivity to chromate and eczema of dyshidrotic morphology. Nor was it possible to correlate the degree of patch test reactivity to the reaction following chromate ingestion. It is concluded that a low-chromate diet is of value in the management of patients with chronic chromate dermatitis.","The significance of chromate ingestion in patients allergic to chromate Abs: A double-blind study was carried out to demonstrate the significance of chromate ingestion in the persistence of chromic chromate dermatitis. Each of 31 chromate-allergic patients was given one tablet containing 7.1 mg potassium dichromate, plus a placebo tablet. The dermatitis of 11 of the 31 patients flared after the ingestion of chromate, but not after placebo. 3 patients had equivocal reactions to both tablets; the dermatitis worsened in 2 patients following ingestion of the placebo but not after the chromate tablet. No statistically significant difference could be found between reactivity to chromate and eczema of dyshidrotic morphology. Nor was it possible to correlate the degree of patch test reactivity to the reaction following chromate ingestion. It is concluded that a low-chromate diet is of value in the management of patients with chronic chromate dermatitis."
14410,Jansen and  Berrens 1968,Sensitization and partial desensitization of guinea-pigs to trivalent and hexavalent chromium,,Sensitization and partial desensitization of guinea-pigs to trivalent and hexavalent chromium Abs: 
14405,Ivankovic and  Preussmann 1975,Absence of toxic and carcinogenic effects after administration of high doses of chromic oxide pigment in subacute and long-term feeding experiments in rats,"HEEP COPYRIGHT: BIOL ABS. The picment chromic oxide (Cr2O3), which as chromium oxide green (C-green 9) or pigment green 17 is used as a cosmetics coloring, was tested in BD rats for subacute toxicity (90-day test) and for long-term toxicity and carcinogenicity (2-yr study). Administration of 2 or 5% in the feed for 90 days produced no signs of toxic effect and no detectable differences from untreated controls. Fertility of the animals was normal during treatment, and the young showed no malformations. Feeding of 1,2 or 5% Cr2O3 in the feed for 2 yr was well tolerated. The animals were observed throughout life and there was no reduction in the average life expectancy of the experimental animals. Even with the very high oral doses of Cr2O3 given, no carcinogenic action was detected.","Absence of toxic and carcinogenic effects after administration of high doses of chromic oxide pigment in subacute and long-term feeding experiments in rats Abs: HEEP COPYRIGHT: BIOL ABS. The picment chromic oxide (Cr2O3), which as chromium oxide green (C-green 9) or pigment green 17 is used as a cosmetics coloring, was tested in BD rats for subacute toxicity (90-day test) and for long-term toxicity and carcinogenicity (2-yr study). Administration of 2 or 5% in the feed for 90 days produced no signs of toxic effect and no detectable differences from untreated controls. Fertility of the animals was normal during treatment, and the young showed no malformations. Feeding of 1,2 or 5% Cr2O3 in the feed for 2 yr was well tolerated. The animals were observed throughout life and there was no reduction in the average life expectancy of the experimental animals. Even with the very high oral doses of Cr2O3 given, no carcinogenic action was detected."
14404,Iijima et al. 1979,Embryotoxic and fetotoxic effects of chromium trioxide in mice,,Embryotoxic and fetotoxic effects of chromium trioxide in mice Abs: 
14401,Hunter and  Roberts 1933,Experimental study of the effects of potassium bichromate on the monkey's kidney,"Monkeys treated repeatedly with 2-6 milliliters of a 2 percent potassium-bichromate (7778509) solution, injected subcutaneously, developed diffuse injury of the proximal and distal convoluted tubules and glomeruli of the kidney resembling the lesions induced by uranium-nitrate and mercuric-chloride (7487947). Chronic kidney lesions were obtained in only one of the 6 monkeys tested.","Experimental study of the effects of potassium bichromate on the monkey's kidney Abs: Monkeys treated repeatedly with 2-6 milliliters of a 2 percent potassium-bichromate (7778509) solution, injected subcutaneously, developed diffuse injury of the proximal and distal convoluted tubules and glomeruli of the kidney resembling the lesions induced by uranium-nitrate and mercuric-chloride (7487947). Chronic kidney lesions were obtained in only one of the 6 monkeys tested."
14400,Hueper and  Payne 1959,Experimental cancers in rats produced by chromium compounds and their significance to industry and public health,,Experimental cancers in rats produced by chromium compounds and their significance to industry and public health Abs: 
14390,Hayes et al. 1979,Mortality in chromium chemical production workers: A prospective study,"Mortality among male employees was studied in a chromium chemical production plant, part of which was rebuilt in 1950-51 and the remainder in 1960, to reduce exposure to chromium bearing dusts. Of 2 101 employees initially employed between 1945 and 1974 and having worked at least 90 days, the vital status of 88% was ascertained, as of mid-1977. Lung cancer mortality for hourly workers initially employed between 1945 and 1959 was significantly higher than in the comparison Baltimore City population (SMR = 2.0), yet it was lower than that reported in previous studies of this industry. A dose response effect was evident from the relationship between duration of employment and mortality. The lung cancer mortality among those employed for three or more years exclusively in the new facility was similar to that observed for such long-term workers in other parts of the plant. Specific job positions were examined. A history of employment in the Bichromate and Special Products Department (production of chromic acid and other products), known as the 'wet end', was associated with the increased lung cancer mortality in contrast to the Mill and Roast Department, known as the 'dry end'. Because of the long latency period associated with chromium exposure and cancer, it was not possible to adequately assess the risk of cancer for workers initially employed after 1960. Methodological issues related to these findings are discussed.","Mortality in chromium chemical production workers: A prospective study Abs: Mortality among male employees was studied in a chromium chemical production plant, part of which was rebuilt in 1950-51 and the remainder in 1960, to reduce exposure to chromium bearing dusts. Of 2 101 employees initially employed between 1945 and 1974 and having worked at least 90 days, the vital status of 88% was ascertained, as of mid-1977. Lung cancer mortality for hourly workers initially employed between 1945 and 1959 was significantly higher than in the comparison Baltimore City population (SMR = 2.0), yet it was lower than that reported in previous studies of this industry. A dose response effect was evident from the relationship between duration of employment and mortality. The lung cancer mortality among those employed for three or more years exclusively in the new facility was similar to that observed for such long-term workers in other parts of the plant. Specific job positions were examined. A history of employment in the Bichromate and Special Products Department (production of chromic acid and other products), known as the 'wet end', was associated with the increased lung cancer mortality in contrast to the Mill and Roast Department, known as the 'dry end'. Because of the long latency period associated with chromium exposure and cancer, it was not possible to adequately assess the risk of cancer for workers initially employed after 1960. Methodological issues related to these findings are discussed."
14364,Gale 1982,The embryotoxic response to maternal chromium trioxide exposure in different strains of hamsters,"HEEP COPYRIGHT: BIOL ABS. Chromium trioxide-induced embryotoxic effects are compared among 1 noninbred (LVG) and 5 inbred (CB, LHC, LSH, MHA, PD4) strains of hamsters. A single dose of chromium trioxide (8 mg/kg, i.v.) was injected into pregnant hamsters on the morning of gestation day 8. Treated and control animals were killed on gestation day 15 and studied for the types and incidence of external and internal abnormalities, and the frequency of resorption sites per uterus. Embryotoxic effects included significant rates of resorptions, external abnormalities, cleft palate and hydrocephalus. The MHA, LSH and LVG strains are susceptible, while the CB, LHC and PD4 strains are resistant to chromium trioxide-induced embryotoxicity. This study was compared with prior work in which the same hamster strains were treated with either Cd, Pb or Hg.","The embryotoxic response to maternal chromium trioxide exposure in different strains of hamsters Abs: HEEP COPYRIGHT: BIOL ABS. Chromium trioxide-induced embryotoxic effects are compared among 1 noninbred (LVG) and 5 inbred (CB, LHC, LSH, MHA, PD4) strains of hamsters. A single dose of chromium trioxide (8 mg/kg, i.v.) was injected into pregnant hamsters on the morning of gestation day 8. Treated and control animals were killed on gestation day 15 and studied for the types and incidence of external and internal abnormalities, and the frequency of resorption sites per uterus. Embryotoxic effects included significant rates of resorptions, external abnormalities, cleft palate and hydrocephalus. The MHA, LSH and LVG strains are susceptible, while the CB, LHC and PD4 strains are resistant to chromium trioxide-induced embryotoxicity. This study was compared with prior work in which the same hamster strains were treated with either Cd, Pb or Hg."
14363,Gale and  III 1979,The effect of the time of administration of chromium trioxide on the embryotoxic response in hamsters,"HEEP COPYRIGHT: BIOL ABS. CrO3 is embryotoxic in hamsters if administered to pregnant animals early on the 8th gestation day. The major manifestations are cleft palate and an increased frequency of resorptions. A single i.v. dose (8 mg/kg) of CrO3 was injected into pregnant hamsters at 0800 h on either day 7, 8, 9, 10 or 11 of gestation in order to determine the effect of altering the time of treatment on embryotoxicity. Fetuses from females treated with Cr or demineralized-distilled water were collected on day 15 of gestation and were examined for the types and frequency of external and internal malformations. The number of resorption sites was recorded. Cleft palate, the major malformation detected, was produced only when Cr was administered on days 7, 8 or 9 of gestation. Since the frequency of resorptions and the incidence of cleft palate varied with the time of treatment, the time at which CrO3 is injected into the pregnant hamster apparently influences embryotoxicity. An interference with embryonic growth may be an important factor in Cr induced cleft palate in hamsters.","The effect of the time of administration of chromium trioxide on the embryotoxic response in hamsters Abs: HEEP COPYRIGHT: BIOL ABS. CrO3 is embryotoxic in hamsters if administered to pregnant animals early on the 8th gestation day. The major manifestations are cleft palate and an increased frequency of resorptions. A single i.v. dose (8 mg/kg) of CrO3 was injected into pregnant hamsters at 0800 h on either day 7, 8, 9, 10 or 11 of gestation in order to determine the effect of altering the time of treatment on embryotoxicity. Fetuses from females treated with Cr or demineralized-distilled water were collected on day 15 of gestation and were examined for the types and frequency of external and internal malformations. The number of resorption sites was recorded. Cleft palate, the major malformation detected, was produced only when Cr was administered on days 7, 8 or 9 of gestation. Since the frequency of resorptions and the incidence of cleft palate varied with the time of treatment, the time at which CrO3 is injected into the pregnant hamster apparently influences embryotoxicity. An interference with embryonic growth may be an important factor in Cr induced cleft palate in hamsters."
14362,Gale 1978,Embryotoxic effects of chromium trioxide in hamsters,"HEEP COPYRIGHT: BIOL ABS. Chromium trioxide was administered i.v. at 5, 7.5, 10 and 15 mg/kg to pregnant golden hamsters early on the 8th gestation day. Fetuses were collected on days 12, 14 and 15 of gestation and examined for the frequency and types of external, internal and skeletal malformations. Exposure of hamsters to this chemical form of a ubiquitous metallic element can kill fetuses in utero and produce edema and retardation and specific malformations in surviving fetuses. The most interesting malformations included cleft palate and defects in the ossification of the skeletal system. Other teratogenic agents were discussed with particular emphasis on mechanisms of cleft palate formation.","Embryotoxic effects of chromium trioxide in hamsters Abs: HEEP COPYRIGHT: BIOL ABS. Chromium trioxide was administered i.v. at 5, 7.5, 10 and 15 mg/kg to pregnant golden hamsters early on the 8th gestation day. Fetuses were collected on days 12, 14 and 15 of gestation and examined for the frequency and types of external, internal and skeletal malformations. Exposure of hamsters to this chemical form of a ubiquitous metallic element can kill fetuses in utero and produce edema and retardation and specific malformations in surviving fetuses. The most interesting malformations included cleft palate and defects in the ossification of the skeletal system. Other teratogenic agents were discussed with particular emphasis on mechanisms of cleft palate formation."
14358,Frentzel-Beyme 1983,Lung cancer mortality of workers employed in chromate pigment factories: a multicentric European epidemiological study,"This study was designed in an attempt to quantify the mortality from cancer and other diseases among workers of European factories producing chromate pigments. The prevailing mixed exposures to zinc as well as lead chromate pigment--although the latter was produced predominantly over the whole period of time made it impossible to distinguish those persons exposed to lead chromate pigment. This report deals with cancer of the respiratory tract and lung cancer in particular. The total workforce of each factory included in the study was followed up, more successfully when they were employed before 1960 than after that time owing to the rising number of foreign nationals. Observed deaths from five factories were compared with expected deaths calculated on the basis of mortality figures for the region in which a given factory was located. Further analysis concerned data of relevant cohorts, which comprised only persons observed for a minimum of 10 years (i.e., exposure beginning before 1965), certainty of complete records for the entire staff to assure a complete cohort instead of prevailing healthy survivors, and exclusion of all foreign nationals. As a result, the overall mortality did not deviate from the expected rates. Lung-cancer rates were always in excess of expected numbers, although only in one cohort to a statistically significant extent. The pattern of duration of exposure indicates that the lung-cancer risk does not show a clear dose-response effect with time of employment. Due to the mixed nature of exposure, conclusions must be limited with the effect that the results obtained are consistent with the hypothesis that working in a chrome-processing plant environment is associated with an increased incidence of lung cancer and with a higher probability of dying from lung cancer compared with the general population.","Lung cancer mortality of workers employed in chromate pigment factories: a multicentric European epidemiological study Abs: This study was designed in an attempt to quantify the mortality from cancer and other diseases among workers of European factories producing chromate pigments. The prevailing mixed exposures to zinc as well as lead chromate pigment--although the latter was produced predominantly over the whole period of time made it impossible to distinguish those persons exposed to lead chromate pigment. This report deals with cancer of the respiratory tract and lung cancer in particular. The total workforce of each factory included in the study was followed up, more successfully when they were employed before 1960 than after that time owing to the rising number of foreign nationals. Observed deaths from five factories were compared with expected deaths calculated on the basis of mortality figures for the region in which a given factory was located. Further analysis concerned data of relevant cohorts, which comprised only persons observed for a minimum of 10 years (i.e., exposure beginning before 1965), certainty of complete records for the entire staff to assure a complete cohort instead of prevailing healthy survivors, and exclusion of all foreign nationals. As a result, the overall mortality did not deviate from the expected rates. Lung-cancer rates were always in excess of expected numbers, although only in one cohort to a statistically significant extent. The pattern of duration of exposure indicates that the lung-cancer risk does not show a clear dose-response effect with time of employment. Due to the mixed nature of exposure, conclusions must be limited with the effect that the results obtained are consistent with the hypothesis that working in a chrome-processing plant environment is associated with an increased incidence of lung cancer and with a higher probability of dying from lung cancer compared with the general population."
14350,Fradkin et al. 1975,In vitro transformation of BHK21 cells grown in the presence of calcium chromate,"Concentrations of 0.25 and 0.5 Ág/ml calcium chromate (CaCrO4À2H2O) dissolved in Dulbecco's medium were found to alter the growth behavior of BHK21 cells in culture. Treated cells grew as shortened fibroblasts and in random orientation. The changes detected during the first two weeks of culture in the presence of the metal became more pronounced as the number of growth passages increased. In addition to the alterations noted above, chromate-treated cells grew into large clusters in Methocel (an alternative technique to the agar suspension system), while untreated cells underwent, at most, only one or two divisions in Methocel. These alterations in growth properties were irreversible and persisted after removal of the treated cells from chromate-containing medium, suggesting that a heritable change had occurred as opposed to a transient, chromate-dependent alteration of cell growth. This experimental observation suggests that chromate salts and perhaps salts of other metals can transform BHK21 cells in vitro or can select for spontaneously transformed cells.","In vitro transformation of BHK21 cells grown in the presence of calcium chromate Abs: Concentrations of 0.25 and 0.5 Ág/ml calcium chromate (CaCrO4À2H2O) dissolved in Dulbecco's medium were found to alter the growth behavior of BHK21 cells in culture. Treated cells grew as shortened fibroblasts and in random orientation. The changes detected during the first two weeks of culture in the presence of the metal became more pronounced as the number of growth passages increased. In addition to the alterations noted above, chromate-treated cells grew into large clusters in Methocel (an alternative technique to the agar suspension system), while untreated cells underwent, at most, only one or two divisions in Methocel. These alterations in growth properties were irreversible and persisted after removal of the treated cells from chromate-containing medium, suggesting that a heritable change had occurred as opposed to a transient, chromate-dependent alteration of cell growth. This experimental observation suggests that chromate salts and perhaps salts of other metals can transform BHK21 cells in vitro or can select for spontaneously transformed cells."
14349,Fornace et al. 1981,DNA-protein cross-linking by chromium salts,"DNA-protein cross-links were detected in several types of mammalian cells in culture when they were exposed to chromate salts. The cell types included human bronchial epithelial cells--the apparent cell type of origin of the malignancies reported in chromate workers. The level of cross-linking was proportional to the concentration of chromate used. These cross-links appeared to be persistent since no removal was seen after 12 h of repair incubation. A low level of DNA single strand breaks (SSB) were also induced after exposure of the cells to chromate but were rejoined after 4 h of repair incubation. The active form of chromium appears to be the trivalent since chromic but not chromate salts induced DNA-protein cross-links in isolated nuclei. Chromic salts also produced cross-linking between DNA and protein in solution while the hexavalent form was inactive. These data imply that chromate crosses the cell membrane, is reduced to the trivalent form and induces stable linkages of DNA to protein.","DNA-protein cross-linking by chromium salts Abs: DNA-protein cross-links were detected in several types of mammalian cells in culture when they were exposed to chromate salts. The cell types included human bronchial epithelial cells--the apparent cell type of origin of the malignancies reported in chromate workers. The level of cross-linking was proportional to the concentration of chromate used. These cross-links appeared to be persistent since no removal was seen after 12 h of repair incubation. A low level of DNA single strand breaks (SSB) were also induced after exposure of the cells to chromate but were rejoined after 4 h of repair incubation. The active form of chromium appears to be the trivalent since chromic but not chromate salts induced DNA-protein cross-links in isolated nuclei. Chromic salts also produced cross-linking between DNA and protein in solution while the hexavalent form was inactive. These data imply that chromate crosses the cell membrane, is reduced to the trivalent form and induces stable linkages of DNA to protein."
14341,Evans 1977,Health hazard evaluation determination; report no 76-88-380 Minnesota Mining and Manufacturing Co,"A Health Hazard Evaluation investigation was conducted by NIOSH at the chromic-oxide (1308389) producing area (SIC-2819) of the Minnesota Mining and Manufacturing Company, Copley, Ohio, on November 29-30, 1976. The investigation was prompted by a request from an authorized representative of employees to evaluate the potential hazard associated with employee exposure to chromate pigments. Seven affected employees were interviewed and an environmental survey was conducted by obtaining time weighted average and ceiling measurements of employee exposure to hexavalent chromium (7440473) and trivalent chromium. Based on environmental samplings, evaluation of ventilation systems, observations of employee work practices, and available toxicity information it is concluded that employee exposures to noncarcinogenic hexavalent chromium contained in sodium-bichromate (10588019), as measured during the survey, did not constitute a health hazard. All atmospheric levels of hexavalent chromium were below evaluation criteria. Although no standards exist from trivalent chromium, recommendation are made for preventing the release of trivalent chromium dust in the air. Certain employees who had experienced nosebleeds and other hexavalent chromium related problems in the past had not experienced such problems for at least 1.5 to 2 years of work, probably as a result of the installation of local exhaust ventilation to prevent exposure.","Health hazard evaluation determination; report no 76-88-380 Minnesota Mining and Manufacturing Co Abs: A Health Hazard Evaluation investigation was conducted by NIOSH at the chromic-oxide (1308389) producing area (SIC-2819) of the Minnesota Mining and Manufacturing Company, Copley, Ohio, on November 29-30, 1976. The investigation was prompted by a request from an authorized representative of employees to evaluate the potential hazard associated with employee exposure to chromate pigments. Seven affected employees were interviewed and an environmental survey was conducted by obtaining time weighted average and ceiling measurements of employee exposure to hexavalent chromium (7440473) and trivalent chromium. Based on environmental samplings, evaluation of ventilation systems, observations of employee work practices, and available toxicity information it is concluded that employee exposures to noncarcinogenic hexavalent chromium contained in sodium-bichromate (10588019), as measured during the survey, did not constitute a health hazard. All atmospheric levels of hexavalent chromium were below evaluation criteria. Although no standards exist from trivalent chromium, recommendation are made for preventing the release of trivalent chromium dust in the air. Certain employees who had experienced nosebleeds and other hexavalent chromium related problems in the past had not experienced such problems for at least 1.5 to 2 years of work, probably as a result of the installation of local exhaust ventilation to prevent exposure."
14340,Evans 1977,"Health hazard evaluation determination report number 76-87-379, Hercules, Inc, Glens Falls Plant, Glens Falls, New York","A Health Hazard Evaluation investigation was conducted by NIOSH at the Hercules chromate pigment manufacturing plant (SIC-2816), Glens Falls, New York, on August 3-4 and October 4-6, 1976. An authorized representative of employees requested the investigation, after preliminary results from a Dry Color Manufacturer's Association sponsored study showed a higher than expected incidence of lung cancer mortality among chromate pigment producers. The medical files of all of the approximately 80 affected employees were reviewed, while 15 such employees were also interviewed. Environmental survey of the work area, including materials used, ventilation and work practices, revealed that seven employees were exposed to atmospheric levels of hexavalent chromium (7440473) exceeding the current ceiling levels, ranging from 7.5 to 98.2 micrograms per cubic meter; three employees were exposed to atmospheric levels of inorganic lead (7439921) exceeding the current recommended ceilings for lead, ranging from 160 to 200 micrograms per cubic meter. No personal samples exceeded current OSHA standards for either hexavalent chromium or inorganic lead. Recommendations are made for improved ventilation, labeling of lead chromates, personal protective equipment, work practices and medical controls.","Health hazard evaluation determination report number 76-87-379, Hercules, Inc, Glens Falls Plant, Glens Falls, New York Abs: A Health Hazard Evaluation investigation was conducted by NIOSH at the Hercules chromate pigment manufacturing plant (SIC-2816), Glens Falls, New York, on August 3-4 and October 4-6, 1976. An authorized representative of employees requested the investigation, after preliminary results from a Dry Color Manufacturer's Association sponsored study showed a higher than expected incidence of lung cancer mortality among chromate pigment producers. The medical files of all of the approximately 80 affected employees were reviewed, while 15 such employees were also interviewed. Environmental survey of the work area, including materials used, ventilation and work practices, revealed that seven employees were exposed to atmospheric levels of hexavalent chromium (7440473) exceeding the current ceiling levels, ranging from 7.5 to 98.2 micrograms per cubic meter; three employees were exposed to atmospheric levels of inorganic lead (7439921) exceeding the current recommended ceilings for lead, ranging from 160 to 200 micrograms per cubic meter. No personal samples exceeded current OSHA standards for either hexavalent chromium or inorganic lead. Recommendations are made for improved ventilation, labeling of lead chromates, personal protective equipment, work practices and medical controls."
14339,Evans 1977,"Health hazard evaluation determination; report no 76-86-389 Allied Chemical Corporation; Marcus Hook, Pennsylvania","A Health Hazard Evaluation investigation was conducted by NIOSH in the chromium nitrate production (SIC-2819) area of the Allied Chemical Corporation facility in Marcus Hook, Pa., on November 21, 1976. An authorized representative of the employees requested the investigation in order to determine whether any substances normally found in the work areas had potentially toxic effects in the prevailing concentrations. The employee exposure to hexavalent chromium, as measured during the survey, did constitute a potential health hazard, both samples taken exceeding the OSHA ceiling standards of 100 micrograms of hexavalent chromium per cubic meter of air for chromic-acid (7738945) and chromates, as well as the NIOSH recommended ceiling of 50 micrograms per cubic meter for noncarcinogenic hexavalent chromium. Neither sample exceeded the recommended standard of 25 micrograms per cubic meter of breathing zone. The interview of one ""affected"" employee failed to reveal any health complaints. Recommended engineering controls to eliminate the potential health hazard include capture velocities of 100 to 200 feet per minute to control the dust release, a lateral local exhaust system around the rim of the material addition porthole, and improved respiratory protection program. A medical surveillance program that will allow the monitoring of chronic diseases, especially cancer, is also recommended.","Health hazard evaluation determination; report no 76-86-389 Allied Chemical Corporation; Marcus Hook, Pennsylvania Abs: A Health Hazard Evaluation investigation was conducted by NIOSH in the chromium nitrate production (SIC-2819) area of the Allied Chemical Corporation facility in Marcus Hook, Pa., on November 21, 1976. An authorized representative of the employees requested the investigation in order to determine whether any substances normally found in the work areas had potentially toxic effects in the prevailing concentrations. The employee exposure to hexavalent chromium, as measured during the survey, did constitute a potential health hazard, both samples taken exceeding the OSHA ceiling standards of 100 micrograms of hexavalent chromium per cubic meter of air for chromic-acid (7738945) and chromates, as well as the NIOSH recommended ceiling of 50 micrograms per cubic meter for noncarcinogenic hexavalent chromium. Neither sample exceeded the recommended standard of 25 micrograms per cubic meter of breathing zone. The interview of one ""affected"" employee failed to reveal any health complaints. Recommended engineering controls to eliminate the potential health hazard include capture velocities of 100 to 200 feet per minute to control the dust release, a lateral local exhaust system around the rim of the material addition porthole, and improved respiratory protection program. A medical surveillance program that will allow the monitoring of chronic diseases, especially cancer, is also recommended."
14338,Evan et al. 1974,The effects of sodium chromate on the proximal tubules of the rat kidney: fine structural damage and lysozymuria,"HEEP COPYRIGHT: BIOL ABS. Sodium chromate (10 or 20 mg/kg i.p.) induces structural changes which appear to be correlated with the amount of lysoz-me in the urine. Chromate selectively affects the cells of the convoluted portion of the proximal tubule. The sequence of progressive changes leading to nephron damage are: swelling and loss of microvilli; formation of intracellular vacuoles of varied sizes; mitochondrial swelling; and cytoplasmic liquefaction followed by desquamation. Tubular damage is greater at higher dose levels and at longer time intervals. The amount of lysozyme in the urine increases as damage to the proximal tubule cells becomes more pronounced, suggesting that urinary lysozyme activity may be a good indicator of severe proximal tubular damage.","The effects of sodium chromate on the proximal tubules of the rat kidney: fine structural damage and lysozymuria Abs: HEEP COPYRIGHT: BIOL ABS. Sodium chromate (10 or 20 mg/kg i.p.) induces structural changes which appear to be correlated with the amount of lysoz-me in the urine. Chromate selectively affects the cells of the convoluted portion of the proximal tubule. The sequence of progressive changes leading to nephron damage are: swelling and loss of microvilli; formation of intracellular vacuoles of varied sizes; mitochondrial swelling; and cytoplasmic liquefaction followed by desquamation. Tubular damage is greater at higher dose levels and at longer time intervals. The amount of lysozyme in the urine increases as damage to the proximal tubule cells becomes more pronounced, suggesting that urinary lysozyme activity may be a good indicator of severe proximal tubular damage."
14327,Denton et al. 1954,The chromium content of cement and its significance in cement dermatitis,"Colorimetric analysis is made of seven samples of type 1 portland cement to determine the concentrations of hexavalent-chromium (7440473) and total chromium in cement washing, water insoluble residues, and original cement powders. Patch tests are made on a patient with an allergic contact type dermatitis due to potassium-dichromate (7778509), indicating that allergic hypersensitivity to hexavalent-chromium as found in aqueous washings of cement powder may be a contributing factor in some cases of cement dermatitis.","The chromium content of cement and its significance in cement dermatitis Abs: Colorimetric analysis is made of seven samples of type 1 portland cement to determine the concentrations of hexavalent-chromium (7440473) and total chromium in cement washing, water insoluble residues, and original cement powders. Patch tests are made on a patient with an allergic contact type dermatitis due to potassium-dichromate (7778509), indicating that allergic hypersensitivity to hexavalent-chromium as found in aqueous washings of cement powder may be a contributing factor in some cases of cement dermatitis."
14322,De Flora 1981,Study of 106 organic and inorganic compounds in the Salmonella/microsome test,"One hundred and six compounds, subdivided into 12 chemical classes (5 polycyclic aromatic hydrocarbons, 7 epoxides and N-oxides, 5 nitro aromatics and heterocyles, 12 aromatic and heterocyclic amines, 2 azo compounds, 17 hydrazine derivatives, 16 miscellaneous aliphatics, 5 miscellaneous heterocycles, 11 miscellaneous organics, 11 hexavalent and 7 trivalent chromium compounds, 8 miscellaneous inorganics), were studied in the Salmonella/microsome test. Fifty-eight of them (54.7%) were found to be mutagenic and 4 additional compounds (3.8%) yielded a positive response following nitrosation in human gastric juice. The results are presented in a tabulated form, providing the following information for each test compound: (a) mutagenic response in 5 S. typhimurium his - strains (TA1535, TA1537, TA1538, TA98, TAI00); (b) ranged of activity for positive compounds or maximum dose tested for negative compounds (in nmol/plate); (c) mutagenic potency (in revertants/umol compound), varying over a 6.5 x 106-fold range; (d) effect of S-9 mix containing rat (Aroclor) liver S-9 fractions on the mutagenic response (activation, increase, no change or decrease): (e) remarks concerning the influence of other metabolic systems (up to 10 different rat tissue S-9 fractions, mouse S-9 fractions, human S-9 fractions, cell reparations or biological fluids), the interaction between different compounds, the stability and the formation of mutagenic derivatives in human gastric juice and other experimental details. Overlapping of mutagenicity and carcinogenicity data was not evaluated, since the experimental protocol intentionally included a number of non-carcinogenic mutagens and of non-mutagenic carcinogens with the aim of explaining in some cases the conflicting nature of in vivo and in vitro conclusions.","Study of 106 organic and inorganic compounds in the Salmonella/microsome test Abs: One hundred and six compounds, subdivided into 12 chemical classes (5 polycyclic aromatic hydrocarbons, 7 epoxides and N-oxides, 5 nitro aromatics and heterocyles, 12 aromatic and heterocyclic amines, 2 azo compounds, 17 hydrazine derivatives, 16 miscellaneous aliphatics, 5 miscellaneous heterocycles, 11 miscellaneous organics, 11 hexavalent and 7 trivalent chromium compounds, 8 miscellaneous inorganics), were studied in the Salmonella/microsome test. Fifty-eight of them (54.7%) were found to be mutagenic and 4 additional compounds (3.8%) yielded a positive response following nitrosation in human gastric juice. The results are presented in a tabulated form, providing the following information for each test compound: (a) mutagenic response in 5 S. typhimurium his - strains (TA1535, TA1537, TA1538, TA98, TAI00); (b) ranged of activity for positive compounds or maximum dose tested for negative compounds (in nmol/plate); (c) mutagenic potency (in revertants/umol compound), varying over a 6.5 x 106-fold range; (d) effect of S-9 mix containing rat (Aroclor) liver S-9 fractions on the mutagenic response (activation, increase, no change or decrease): (e) remarks concerning the influence of other metabolic systems (up to 10 different rat tissue S-9 fractions, mouse S-9 fractions, human S-9 fractions, cell reparations or biological fluids), the interaction between different compounds, the stability and the formation of mutagenic derivatives in human gastric juice and other experimental details. Overlapping of mutagenicity and carcinogenicity data was not evaluated, since the experimental protocol intentionally included a number of non-carcinogenic mutagens and of non-mutagenic carcinogens with the aim of explaining in some cases the conflicting nature of in vivo and in vitro conclusions."
14319,Davies 1979,Lung cancer mortality of workers in chromate pigment manufacture: an epidemiological survey,"A study of lung cancer mortality in chromate (13907454) pigment manufacturing workers was conducted. The cohort consisted of 646 males employed for at least 1 year before 1968 at three chromate pigment factories (SIC-2816) in the United Kingdom. Two factories manufactured lead-chromate (18454121) and zinc-chromate (13530659). The third manufactured only lead-chromate. Company personnel records were reviewed. The chromate exposures of the subjects were estimated on the basis of their job titles. Subjects employed in departments where pigments were ground, blended, and packed were classified as having high exposure. Subjects working in departments where precipitates were washed, pressed, and stove dried were considered to have medium exposure. Workers employed in laboratories, boiler stoking, painting, and bricklaying were classified as having low exposure. The vital status of the cohort was determined as of 1977 utilizing records maintained by the National Health Service Central Register. Death certificates were obtained for the deceased subjects. The observed lung cancer mortality was compared with that of the national rates for all males in England and Wales. No excess lung cancer mortality occurred in workers classified as having low exposure or in those exposed only to lead-chromate. A significant excess of lung cancer deaths occurred in workers classified as high or medium exposures to both zinc-chromate and lead-chromate. The latency periods of the deaths ranged from 5 to 25 years after first exposure. The author suggests that manufacturing zinc-chromate presents a risk of lung cancer. Although no evidence was found that lead-chromate causes lung cancer, it cannot be unequivocably stated that heavy exposures to lead-chromate do not present a cancer hazard.","Lung cancer mortality of workers in chromate pigment manufacture: an epidemiological survey Abs: A study of lung cancer mortality in chromate (13907454) pigment manufacturing workers was conducted. The cohort consisted of 646 males employed for at least 1 year before 1968 at three chromate pigment factories (SIC-2816) in the United Kingdom. Two factories manufactured lead-chromate (18454121) and zinc-chromate (13530659). The third manufactured only lead-chromate. Company personnel records were reviewed. The chromate exposures of the subjects were estimated on the basis of their job titles. Subjects employed in departments where pigments were ground, blended, and packed were classified as having high exposure. Subjects working in departments where precipitates were washed, pressed, and stove dried were considered to have medium exposure. Workers employed in laboratories, boiler stoking, painting, and bricklaying were classified as having low exposure. The vital status of the cohort was determined as of 1977 utilizing records maintained by the National Health Service Central Register. Death certificates were obtained for the deceased subjects. The observed lung cancer mortality was compared with that of the national rates for all males in England and Wales. No excess lung cancer mortality occurred in workers classified as having low exposure or in those exposed only to lead-chromate. A significant excess of lung cancer deaths occurred in workers classified as high or medium exposures to both zinc-chromate and lead-chromate. The latency periods of the deaths ranged from 5 to 25 years after first exposure. The author suggests that manufacturing zinc-chromate presents a risk of lung cancer. Although no evidence was found that lead-chromate causes lung cancer, it cannot be unequivocably stated that heavy exposures to lead-chromate do not present a cancer hazard."
14318,Davies 1978,Lung-cancer mortality of workers making chrome pigments,"A mortality study was begun in 1975 of three English factories manufacturing chromate pigments. The results presented here related primarily to men entering employment at or after the earliest date from which complete personnel records were maintained and who completed at least 1 year's service. Factory-A and factory-B produced both lead-chromate (7758976) and zinc-chromate (13530659) pigments; factory-C produced only lead-chromate pigments. Worker exposures were classified as high, medium, or low grade according to the date of starting employment, length of service, and level of exposure to chromates. Lung cancer mortality was significantly raised at factory-A for men ranked as being high or medium grade employees, starting employment during the period 1932 through 1954. No excess deaths were noted among workers in the low category. At factory-B the cancer death rate was higher for workers in the high and medium grades who began work during 1948 through 1967. Several alterations at factory-B were made in 1968 with subsequent drastic improvements in the working conditions there. There was no excess lung cancer mortality at factory-C. The author suggests that the increased numbers of deaths arising from lung cancer are due to exposure to zinc-chromate pigments.","Lung-cancer mortality of workers making chrome pigments Abs: A mortality study was begun in 1975 of three English factories manufacturing chromate pigments. The results presented here related primarily to men entering employment at or after the earliest date from which complete personnel records were maintained and who completed at least 1 year's service. Factory-A and factory-B produced both lead-chromate (7758976) and zinc-chromate (13530659) pigments; factory-C produced only lead-chromate pigments. Worker exposures were classified as high, medium, or low grade according to the date of starting employment, length of service, and level of exposure to chromates. Lung cancer mortality was significantly raised at factory-A for men ranked as being high or medium grade employees, starting employment during the period 1932 through 1954. No excess deaths were noted among workers in the low category. At factory-B the cancer death rate was higher for workers in the high and medium grades who began work during 1948 through 1967. Several alterations at factory-B were made in 1968 with subsequent drastic improvements in the working conditions there. There was no excess lung cancer mortality at factory-C. The author suggests that the increased numbers of deaths arising from lung cancer are due to exposure to zinc-chromate pigments."
14306,Cikrt and  Bencko 1979,Biliary excretion and distribution of 51Cr(III) and 51Cr(VI) in rats,"The biliary excretion and distribution of 51Cr after intravenous administration of 51Cr(III) (61CrCl5) or 51Cr(VI) (Na252CrO4 . 4 H2O) was studied in rats. The cumulative biliary excretion of 51Cr reached 24 hrs after the injection was significantly higher after administration of 51Cr(VI) than after 51Cr(III) 3.51 +/-0.7% and 0.51+/-0.05% of administered dose, respectively). This difference was especially due to a higher rate of biliary excretion of 51Cr in the first hours after 51Cr(VI) administration. The excretion of 51Cr via faeces was also higher after administration of 51Cr(VI) (7.35+/-0.45%) OF ADMINISTERED DOSE, AS AGAINST 4.23+/-0.23% after 51Cr(III). On the other hand, no significant difference in urinary excretion of 51Cr was found. Statistically significant differences were also observed in the distribution of 51Cr in the organism after administration of both valence states of the metal.","Biliary excretion and distribution of 51Cr(III) and 51Cr(VI) in rats Abs: The biliary excretion and distribution of 51Cr after intravenous administration of 51Cr(III) (61CrCl5) or 51Cr(VI) (Na252CrO4 . 4 H2O) was studied in rats. The cumulative biliary excretion of 51Cr reached 24 hrs after the injection was significantly higher after administration of 51Cr(VI) than after 51Cr(III) 3.51 +/-0.7% and 0.51+/-0.05% of administered dose, respectively). This difference was especially due to a higher rate of biliary excretion of 51Cr in the first hours after 51Cr(VI) administration. The excretion of 51Cr via faeces was also higher after administration of 51Cr(VI) (7.35+/-0.45%) OF ADMINISTERED DOSE, AS AGAINST 4.23+/-0.23% after 51Cr(III). On the other hand, no significant difference in urinary excretion of 51Cr was found. Statistically significant differences were also observed in the distribution of 51Cr in the organism after administration of both valence states of the metal."
14298,Cairns and  Calnan 1962,Green tattoo reactions associated with cement dermatitis,,Green tattoo reactions associated with cement dermatitis Abs: 
14284,Bonatti et al. 1976,Genetic effects of potassium dichromate in Schizosaccharomyces pombe,"HEEP COPYRIGHT: BIOL ABS. As an air pollutant, chromium is normally present in the atmosphere of cities and non-urban areas, where its concentration has been measured. Evidence is presented that gene conversion is induced by K2Cr2 O7 in Schizosaccharomyces pombe. Mutation induction in a forward mutation, 2 genes system is also reported, although this data cannot be considered as definitive proof of mutagenic activity.","Genetic effects of potassium dichromate in Schizosaccharomyces pombe Abs: HEEP COPYRIGHT: BIOL ABS. As an air pollutant, chromium is normally present in the atmosphere of cities and non-urban areas, where its concentration has been measured. Evidence is presented that gene conversion is induced by K2Cr2 O7 in Schizosaccharomyces pombe. Mutation induction in a forward mutation, 2 genes system is also reported, although this data cannot be considered as definitive proof of mutagenic activity."
14277,Berry et al. 1978,"Chromium concentration by proximal renal tubule cells: an ultrastructural, microanalytical and cytochemical study","After treating rats with potassium bichromate, x-ray microanalysis of the proximal renal tubule cells demonstrated the presence of chromium in intracellular vacuoles. The lysosomal nature of these vacuoles is shown by the visualization of acid phosphatase activity. Chromium is concentrated both in the autolytic vacuoles and in their residual forms. The metal is eliminated quite late, concomitant with cellular necrosis.","Chromium concentration by proximal renal tubule cells: an ultrastructural, microanalytical and cytochemical study Abs: After treating rats with potassium bichromate, x-ray microanalysis of the proximal renal tubule cells demonstrated the presence of chromium in intracellular vacuoles. The lysosomal nature of these vacuoles is shown by the visualization of acid phosphatase activity. Chromium is concentrated both in the autolytic vacuoles and in their residual forms. The metal is eliminated quite late, concomitant with cellular necrosis."
14276,Berndt 1976,Renal chromium accumulation and its relationship to chromium-induced nephrotoxicity,"This report is an attempt to study the renal handling of chromium under in vitro conditions and to relate this to the actions of the ion in the production of nephrotoxicity. Renal slice techniques were employed in these studies and were used to examine the effects of chromium on various renal transport processes. In addition, the accumulation of chromium by the renal tissue has also been studied. Marked accumulation by renal cortical slices of the rat was observed when 51Cr-labeled chromate or dichromate was added to the bathing solution. Some metabolic inhibitors interfered with this uptake process; in addition, some substrates metabolized by renal tissue reduced the accumulation of 51Cr. The use of [51Cr] dichromate and [51Cr]-chromate, as well as alterations in the bathing solution pH, indicated that in the rat chromium can interfere with renal transport processes, but that the oxidation state of this metal is not important. On the other hand, in the rabbit a greater interference with 51Cr uptake was noted at lower bathing solution pHs. This is interpreted to mean that chromate is the effective inhibitor in this species.","Renal chromium accumulation and its relationship to chromium-induced nephrotoxicity Abs: This report is an attempt to study the renal handling of chromium under in vitro conditions and to relate this to the actions of the ion in the production of nephrotoxicity. Renal slice techniques were employed in these studies and were used to examine the effects of chromium on various renal transport processes. In addition, the accumulation of chromium by the renal tissue has also been studied. Marked accumulation by renal cortical slices of the rat was observed when 51Cr-labeled chromate or dichromate was added to the bathing solution. Some metabolic inhibitors interfered with this uptake process; in addition, some substrates metabolized by renal tissue reduced the accumulation of 51Cr. The use of [51Cr] dichromate and [51Cr]-chromate, as well as alterations in the bathing solution pH, indicated that in the rat chromium can interfere with renal transport processes, but that the oxidation state of this metal is not important. On the other hand, in the rabbit a greater interference with 51Cr uptake was noted at lower bathing solution pHs. This is interpreted to mean that chromate is the effective inhibitor in this species."
14275,Behari et al. 1978,Comparative toxicity of trivalent and hexavalent chromium to rabbits III Biochemical and histological changes in testicular tissue,"The administration of trivalent and hexavalent chromium compounds produced inhibition of the activity of succinic dehydrogenase, adenosine triphosphatase and acid phosphattase accompanied by cellular degeneration with complete absence of spermatocytes in the testis of rabbits. The biochemical and histological changes were more marked in the animals treated with the trivalent chromium than those exposed to hexavalent chromium and were progressive with the duration of exposure.","Comparative toxicity of trivalent and hexavalent chromium to rabbits III Biochemical and histological changes in testicular tissue Abs: The administration of trivalent and hexavalent chromium compounds produced inhibition of the activity of succinic dehydrogenase, adenosine triphosphatase and acid phosphattase accompanied by cellular degeneration with complete absence of spermatocytes in the testis of rabbits. The biochemical and histological changes were more marked in the animals treated with the trivalent chromium than those exposed to hexavalent chromium and were progressive with the duration of exposure."
14259,Alexander et al. 1982,Uptake of chromium by rat liver mitochondria,"Isolated rat liver mitochondria rapidly accumulate chromate (1.2 microM 51CrO4(2-)) to about 0.25-0.30 nmol Cr/mg protein. The relative uptake decreases with increasing chromate doses. Chromate uptake decreases when pH is raised from 7.0 to 7.5.N-ethylmaleimide (0.25 mM) and butylmalonate (5 mM) inhibit chromate uptake to 70% and 30% of control values, respectively, whereas mersalyl (40 nmol/mg protein) causes an inhibition of greater than 95%. Both sulphate and phosphate decrease mitochondrial chromate uptake, the former being more effective in lower doses (5 mM). These results indicate that transport of chromate is mediated both on the dicarboxylate and the phosphate carrier. The extensive mitochondrial chromium accumulation can be explained by trapping of chromium, probably by reduction of chromate to the trivalent form, within the mitochondria. Release of chromium after chromate loading was seen after 15 min. Added after chromate loading, mersalyl partly prevents this release. Trivalent chromium as 51CrCl3 is taken up to a much lower degree than hexavalent chromium as 51CrO4(2-). The presence of glutathione (5 mM) reduces the uptake both of 51Cr-III and 51Cr-VI, indicating extramitochondrial reduction of Cr-VI to Cr-III and subsequent binding to GSH.","Uptake of chromium by rat liver mitochondria Abs: Isolated rat liver mitochondria rapidly accumulate chromate (1.2 microM 51CrO4(2-)) to about 0.25-0.30 nmol Cr/mg protein. The relative uptake decreases with increasing chromate doses. Chromate uptake decreases when pH is raised from 7.0 to 7.5.N-ethylmaleimide (0.25 mM) and butylmalonate (5 mM) inhibit chromate uptake to 70% and 30% of control values, respectively, whereas mersalyl (40 nmol/mg protein) causes an inhibition of greater than 95%. Both sulphate and phosphate decrease mitochondrial chromate uptake, the former being more effective in lower doses (5 mM). These results indicate that transport of chromate is mediated both on the dicarboxylate and the phosphate carrier. The extensive mitochondrial chromium accumulation can be explained by trapping of chromium, probably by reduction of chromate to the trivalent form, within the mitochondria. Release of chromium after chromate loading was seen after 15 min. Added after chromate loading, mersalyl partly prevents this release. Trivalent chromium as 51CrCl3 is taken up to a much lower degree than hexavalent chromium as 51CrO4(2-). The presence of glutathione (5 mM) reduces the uptake both of 51Cr-III and 51Cr-VI, indicating extramitochondrial reduction of Cr-VI to Cr-III and subsequent binding to GSH."
14247,Langård et al. 1978,Whole blood chromium level and chromium excretion in the rat after zinc chromate inhalation,"Studies on absorption and excretion of chromium in the rat exposed to known atmospheric concentrations of zinc chromate in an inhalation chamber and the influence of diurnal variations in physical activity have been carried out. Chromium analyses were performed on samples of blood, urine and faeces using a method for determining chromium in small samples of biological material based on flameless atomic absorption spectrometry. Zinc chromate is absorbed quickly during exposure and excreted mainly via urine. An accumulation of chromium in blood was observed, followed by a slow elimination. It is suggested that chromium from zinc chromate enters the blood in the hexavalent state.","Whole blood chromium level and chromium excretion in the rat after zinc chromate inhalation Abs: Studies on absorption and excretion of chromium in the rat exposed to known atmospheric concentrations of zinc chromate in an inhalation chamber and the influence of diurnal variations in physical activity have been carried out. Chromium analyses were performed on samples of blood, urine and faeces using a method for determining chromium in small samples of biological material based on flameless atomic absorption spectrometry. Zinc chromate is absorbed quickly during exposure and excreted mainly via urine. An accumulation of chromium in blood was observed, followed by a slow elimination. It is suggested that chromium from zinc chromate enters the blood in the hexavalent state."
14242,Pedersen and  Morch 1978,Chromic acid poisoning treated with acute hemodialysis,"Poisoning with chromium compounds is rare, but often serious. The symptoms are quite characteristic, the most dramatic of these being circulatory collapse, hepatic and renal failure. A case is reported where an 18-year-old woman ingested 5 g of chromic acid. She was treated with acute hemodialysis and forced diuresis, and survived with surprisingly few symptoms of poisoning.","Chromic acid poisoning treated with acute hemodialysis Abs: Poisoning with chromium compounds is rare, but often serious. The symptoms are quite characteristic, the most dramatic of these being circulatory collapse, hepatic and renal failure. A case is reported where an 18-year-old woman ingested 5 g of chromic acid. She was treated with acute hemodialysis and forced diuresis, and survived with surprisingly few symptoms of poisoning."
14241,Petrilli and  De Flora 1977,Toxicity and mutagenicity of hexavalent chromium on Salmonella typhimurium,"Four hexavalent and two trivalent chromium compounds were tested for toxicity and mutagenicity by means of the Salmonella typhimurium/mammalian-microsome test. All hexavalent compounds yielded a complete inhibition of bacterial growth at doses of 400 to 800 mug/plate, a significant increase of his(+) revertant colonies at doses ranging from 10 to 200 mug, and no effect at doses of less than 10 mug. The distinctive sensitivity of the four Salmonella strains tested (TA1535, TA1537, TA98, and TA100) suggested that hexavalent chromium directly interacts with bacterial deoxyribonucleic acid by causing both frameshift mutations and basepair substitutions. The latter mutations, which are prevalent, are amplified by an error-prone recombinational repair of the damaged deoxyribonucleic acid. On the average, 1 mumol of hexavalent chromium yielded approximately 500 revertants of the TA100 strain, irrespective of the compound tested (sodium dichromate, calcium chromate, potassium chromate, or chromic acid). The mutagenic potency of the hexavalent metal was not enhanced by adding the microsomal fraction of rat hepatocytes, induced either with sodium barbital or with Aroclor 1254. The two trivalent compounds (chromium potassium sulfate and chromic chloride), with or without the microsomal fraction, were neither toxic nor mutagenic for the bacterial tester strains.","Toxicity and mutagenicity of hexavalent chromium on Salmonella typhimurium Abs: Four hexavalent and two trivalent chromium compounds were tested for toxicity and mutagenicity by means of the Salmonella typhimurium/mammalian-microsome test. All hexavalent compounds yielded a complete inhibition of bacterial growth at doses of 400 to 800 mug/plate, a significant increase of his(+) revertant colonies at doses ranging from 10 to 200 mug, and no effect at doses of less than 10 mug. The distinctive sensitivity of the four Salmonella strains tested (TA1535, TA1537, TA98, and TA100) suggested that hexavalent chromium directly interacts with bacterial deoxyribonucleic acid by causing both frameshift mutations and basepair substitutions. The latter mutations, which are prevalent, are amplified by an error-prone recombinational repair of the damaged deoxyribonucleic acid. On the average, 1 mumol of hexavalent chromium yielded approximately 500 revertants of the TA100 strain, irrespective of the compound tested (sodium dichromate, calcium chromate, potassium chromate, or chromic acid). The mutagenic potency of the hexavalent metal was not enhanced by adding the microsomal fraction of rat hepatocytes, induced either with sodium barbital or with Aroclor 1254. The two trivalent compounds (chromium potassium sulfate and chromic chloride), with or without the microsomal fraction, were neither toxic nor mutagenic for the bacterial tester strains."
14239,Petrilli and  De Flora 1978,Metabolic deactivation of hexavalent chromium mutagenicity,"HEEP COPYRIGHT: BIOL ABS. Hexavalent chromium compounds (sodium dichromate, potassium chromate, chromic acid, basic zinc chromate and basic lead chromate) were found to be mutagenic for his- strains of S. typhimurium by inducing both frameshifts and base-pair substitutions. However, addition of either microsomal fractions from rat liver or of human erythrocyte lysates resulted in a complete loss of mutagenicity. As confirmed by chemical analysis, reversal of mutagenicity could be ascribed to reduction of the metal to the inactive trivalent form through a simple oxido-reductive reaction. In fact, reducing agents (ascorbic acid and sodium sulfite) and metabolites (GSH glutathione, DPNH and TPNH, either directly tested or obtained by mixing G6PD with S-9 mix) prevented hexavalent Cr mutagenicity, whereas an oxidizing agent (potassium permanganate) totally inhibited reversal of mutagenicity by liver and erythrocyte preparations. Enzymic conversion appeared to be involved in deactivation processes through a large production of TPNH via the hexose monophosphate oxidative pathway and other ancillary systems. Microsomal preparations from rat lung displayed an extremely poor inactivating effect on Cr mutagenicity, and those from rat muscle, as well as human serum or plasma, were ineffective. These findings could be relevant for the elective localization of Cr-induced tumors in human lung and could account for the results of animal carcinogenicity tests, which generally showed the development of tumors, but only at implant sites.","Metabolic deactivation of hexavalent chromium mutagenicity Abs: HEEP COPYRIGHT: BIOL ABS. Hexavalent chromium compounds (sodium dichromate, potassium chromate, chromic acid, basic zinc chromate and basic lead chromate) were found to be mutagenic for his- strains of S. typhimurium by inducing both frameshifts and base-pair substitutions. However, addition of either microsomal fractions from rat liver or of human erythrocyte lysates resulted in a complete loss of mutagenicity. As confirmed by chemical analysis, reversal of mutagenicity could be ascribed to reduction of the metal to the inactive trivalent form through a simple oxido-reductive reaction. In fact, reducing agents (ascorbic acid and sodium sulfite) and metabolites (GSH glutathione, DPNH and TPNH, either directly tested or obtained by mixing G6PD with S-9 mix) prevented hexavalent Cr mutagenicity, whereas an oxidizing agent (potassium permanganate) totally inhibited reversal of mutagenicity by liver and erythrocyte preparations. Enzymic conversion appeared to be involved in deactivation processes through a large production of TPNH via the hexose monophosphate oxidative pathway and other ancillary systems. Microsomal preparations from rat lung displayed an extremely poor inactivating effect on Cr mutagenicity, and those from rat muscle, as well as human serum or plasma, were ineffective. These findings could be relevant for the elective localization of Cr-induced tumors in human lung and could account for the results of animal carcinogenicity tests, which generally showed the development of tumors, but only at implant sites."
14237,Venier et al. 1982,"Cytotoxic, mutagenic and clastogenic effects of industrial chromium compounds","Ten Cr(III) compounds, used in the leather tanning industry, and a Cr(III) compound, containing chromite and used as a pigment, were tested for cytotoxicity (inhibition of growth and survival of cultured hamster cells), mutagenicity (point mutations in S. typhimurium) and clastogenic activity (chromosomal aberrations and sister chromatid exchanges in hamster cells). Reference Cr compounds were potassium dichromate as Cr(VI), and chromium chloride and two different preparations of chromium nitrate as Cr(III). A contamination with Cr(VI) was detected in some of the Cr(III) tannins, chromite and one chromium nitrate. Cr(III) compounds were cytotoxic at concentrations of Cr(III) 100-500 times higher than Cr(VI), but contaminated Cr(III) compounds showed a significant cytotoxicity. Reference Cr(VI) but not Cr(III) was mutagenic: of the contaminated compounds only chromite and chromium nitrate, which contained higher levels of Cr(VI), were found to be mutagenic. The frequency of sister chromatid exchanges was significantly increased only by Cr(VI) and the more contaminated Cr(III) compounds. However, an increase of chromosomal aberrations was produced also by reference Cr(III) salts and the weakly contaminated industrial Cr(III) compounds. These results confirm the view that the active mutagenic agent in intact cell systems is Cr(VI), but indicate that industrial Cr(III) compounds cannot be considered genetically inert, as they can be contaminated by Cr(VI) and induce chromosomal aberrations.","Cytotoxic, mutagenic and clastogenic effects of industrial chromium compounds Abs: Ten Cr(III) compounds, used in the leather tanning industry, and a Cr(III) compound, containing chromite and used as a pigment, were tested for cytotoxicity (inhibition of growth and survival of cultured hamster cells), mutagenicity (point mutations in S. typhimurium) and clastogenic activity (chromosomal aberrations and sister chromatid exchanges in hamster cells). Reference Cr compounds were potassium dichromate as Cr(VI), and chromium chloride and two different preparations of chromium nitrate as Cr(III). A contamination with Cr(VI) was detected in some of the Cr(III) tannins, chromite and one chromium nitrate. Cr(III) compounds were cytotoxic at concentrations of Cr(III) 100-500 times higher than Cr(VI), but contaminated Cr(III) compounds showed a significant cytotoxicity. Reference Cr(VI) but not Cr(III) was mutagenic: of the contaminated compounds only chromite and chromium nitrate, which contained higher levels of Cr(VI), were found to be mutagenic. The frequency of sister chromatid exchanges was significantly increased only by Cr(VI) and the more contaminated Cr(III) compounds. However, an increase of chromosomal aberrations was produced also by reference Cr(III) salts and the weakly contaminated industrial Cr(III) compounds. These results confirm the view that the active mutagenic agent in intact cell systems is Cr(VI), but indicate that industrial Cr(III) compounds cannot be considered genetically inert, as they can be contaminated by Cr(VI) and induce chromosomal aberrations."
14235,Pirila and  Kilpio 1949,On dermatoses caused by bichromates,"A total of 45 cases of chromate dermatitis are presented, including 11 printers, 10 cement or lime workers, 7 radio factory workers, 4 chromium (7440473) platers or other metal factory workers, 4 painters or polishers, 3 fur dyers, and 6 workers engaged in various other occupations. The potassium-bichromate (7778509) patch test was positive in 41 cases, including 21 who had manifestations of dermatitis on the face or neck. In the 4 cases with negative patch test, dermatitis was restricted to hands and arms. About 70 percent of the patients had to abstain from work for various periods, while nearly 50 percent required a change of occupation.","On dermatoses caused by bichromates Abs: A total of 45 cases of chromate dermatitis are presented, including 11 printers, 10 cement or lime workers, 7 radio factory workers, 4 chromium (7440473) platers or other metal factory workers, 4 painters or polishers, 3 fur dyers, and 6 workers engaged in various other occupations. The potassium-bichromate (7778509) patch test was positive in 41 cases, including 21 who had manifestations of dermatitis on the face or neck. In the 4 cases with negative patch test, dermatitis was restricted to hands and arms. About 70 percent of the patients had to abstain from work for various periods, while nearly 50 percent required a change of occupation."
14230,Samitz and  Gross 1961,Effects of hexavalent and trivalent chromium compounds on the skin,"Clinical and laboratory studies of the role of chromium compounds in shoe leather dermatitis, of absorption of hexavalent and trivalent chromium compounds in the skin of guinea-pigs, and of conjugation between chromium salts with various proteins and the inactivation of chromium reactions. Polarographic studies of chromium extracted by sweat from shoe leather show both hexavalent and trivalent compounds. Spectrographic analyses of biopsy sections from guinea-pigs tattooed with potassium-dichromate and chromium-nitrate show no significant difference in the absorption of the two types of chromium compounds. Trivalent compounds show an incapability to sensitize patients with proved dichromate sensitivity. An antichrome reagent is developed based on the reduction of hexavalent chromium to the trivalent state with subsequent chelation, capable of inactivating patch test reactions in chromate sensitive patients.","Effects of hexavalent and trivalent chromium compounds on the skin Abs: Clinical and laboratory studies of the role of chromium compounds in shoe leather dermatitis, of absorption of hexavalent and trivalent chromium compounds in the skin of guinea-pigs, and of conjugation between chromium salts with various proteins and the inactivation of chromium reactions. Polarographic studies of chromium extracted by sweat from shoe leather show both hexavalent and trivalent compounds. Spectrographic analyses of biopsy sections from guinea-pigs tattooed with potassium-dichromate and chromium-nitrate show no significant difference in the absorption of the two types of chromium compounds. Trivalent compounds show an incapability to sensitize patients with proved dichromate sensitivity. An antichrome reagent is developed based on the reduction of hexavalent chromium to the trivalent state with subsequent chelation, capable of inactivating patch test reactions in chromate sensitive patients."
14226,Samitz and  Shrager 1966,Patch test reactions to hexavalent and trivalent chromium compounds,,Patch test reactions to hexavalent and trivalent chromium compounds Abs: 
14224,Sarto et al. 1982,Increased incidence of chromosomal aberrations and sister chromatid exchanges in workers exposed to chromic acid (CrO3) in electroplating factories,"Chromosomal aberrations in cultured lymphocytes obtained from workers occupationally exposed to chromic acid (CrO3) were detected. Four separate groups of workers were examined, two of which were engaged in plating factories employing nickel in addition to chromium, and two coming from plating factories where only chromium was used. In the latter groups the frequency of sister chromatid exchanges (SCEs) were also detected in the cultured lymphocytes. A statistically significant increase of chromosomal aberrations, mostly of the chromosome-type, was found in two of the exposed groups of workers compared to the level observed in control donors. The frequency of SCEs in the exposed groups was higher than in controls, particularly in the factor which employed the younger workers. Besides the negative correlation with the age of workers, a positive correlation between the frequency of SCEs and the level of urinary chromium was found and such a correlation was strongly enchanced by smoking. The present data support the view that CrO3, like other soluble hexavalent chromium compounds, is genetically active in vivo.","Increased incidence of chromosomal aberrations and sister chromatid exchanges in workers exposed to chromic acid (CrO3) in electroplating factories Abs: Chromosomal aberrations in cultured lymphocytes obtained from workers occupationally exposed to chromic acid (CrO3) were detected. Four separate groups of workers were examined, two of which were engaged in plating factories employing nickel in addition to chromium, and two coming from plating factories where only chromium was used. In the latter groups the frequency of sister chromatid exchanges (SCEs) were also detected in the cultured lymphocytes. A statistically significant increase of chromosomal aberrations, mostly of the chromosome-type, was found in two of the exposed groups of workers compared to the level observed in control donors. The frequency of SCEs in the exposed groups was higher than in controls, particularly in the factor which employed the younger workers. Besides the negative correlation with the age of workers, a positive correlation between the frequency of SCEs and the level of urinary chromium was found and such a correlation was strongly enchanced by smoking. The present data support the view that CrO3, like other soluble hexavalent chromium compounds, is genetically active in vivo."
14213,Steinhoff et al. 1986,Carcinogenicity study with sodium dichromate in rats,"Solutions of sodium dichromate were administered to Sprague Dawley rats by intratracheal instillations over a period of 30 months. Dosage was 0.01, 0.05 or 0.25 mg/kg, five times a week, or 0.05, 0.25 or 1.25 mg/kg once a week. Each group consisted of 40 male and 40 female rats. Groups left untreated or given saline served as negative controls. The highest chromate dose proved to be within the range of the maximum tolerable amount. The main determinant of effect was the concentration of chromate instilled, not the total dose per week. Non-neoplastic pulmonary lesions, which occurred predominantly in the highest dose group, were fibrotic regions containing residual distorted bronchiolar lumens or cellular inflammatory foci containing alveolar macrophages, proliferated epithelium and chronic inflammatory thickening of alveolar septa. Fourteen rats given 1.25 mg/kg sodium dichromate had a total of 20 lung tumours (12 benign, 8 malignant). One rat given 0.25 mg/kg once a week had a malignant tumour. Tumours were generally small and were non-fatal. A comparable solution of calcium chromate, which was tested at the two highest dose levels, had virtually the same effect. The positive controls, benzo(a)pyrene and dimethylcarbamyl chloride, induced a high rate of fatal malignant tumours in the respiratory tract.","Carcinogenicity study with sodium dichromate in rats Abs: Solutions of sodium dichromate were administered to Sprague Dawley rats by intratracheal instillations over a period of 30 months. Dosage was 0.01, 0.05 or 0.25 mg/kg, five times a week, or 0.05, 0.25 or 1.25 mg/kg once a week. Each group consisted of 40 male and 40 female rats. Groups left untreated or given saline served as negative controls. The highest chromate dose proved to be within the range of the maximum tolerable amount. The main determinant of effect was the concentration of chromate instilled, not the total dose per week. Non-neoplastic pulmonary lesions, which occurred predominantly in the highest dose group, were fibrotic regions containing residual distorted bronchiolar lumens or cellular inflammatory foci containing alveolar macrophages, proliferated epithelium and chronic inflammatory thickening of alveolar septa. Fourteen rats given 1.25 mg/kg sodium dichromate had a total of 20 lung tumours (12 benign, 8 malignant). One rat given 0.25 mg/kg once a week had a malignant tumour. Tumours were generally small and were non-fatal. A comparable solution of calcium chromate, which was tested at the two highest dose levels, had virtually the same effect. The positive controls, benzo(a)pyrene and dimethylcarbamyl chloride, induced a high rate of fatal malignant tumours in the respiratory tract."
14207,Tola et al. 1977,Urinary chromium as an indicator of the exposure of welders to chromium,"Five welders working with high alloy Cr-Ni steel and one working with mild steel were followed during one work week. The chromium concentration in air was measured concomitantly with urinary chromium determinations. The water-soluble chromium concentrations in air exceeded 0.05 mg/m3 during welding with coated electrodes, but metal inert-gas (MIG) welding produced much lower concentrations. The proportion of water-soluble hexavalent chromium in the air was usually more than 50% of the total chromium concentration during welding with coated electrodes, whereas less than 10% of the chromium produced during MIG welding was in a water-soluble. Since water-soluble chromium (hexavalent) is the more important biologically, the determination of both water-soluble and water-insoluble chromium concentrations is emphasized instead of the measurement of the total concentration. The urinary chromium concentration proved to be a good indicator of short-term exposure to water-soluble chromium when exposure was above the current threshold limit value of 0.05 mg/m3, concentrations of more than 30 microgram/g of creatinine representing an exposure level higher than the threshold limit value.","Urinary chromium as an indicator of the exposure of welders to chromium Abs: Five welders working with high alloy Cr-Ni steel and one working with mild steel were followed during one work week. The chromium concentration in air was measured concomitantly with urinary chromium determinations. The water-soluble chromium concentrations in air exceeded 0.05 mg/m3 during welding with coated electrodes, but metal inert-gas (MIG) welding produced much lower concentrations. The proportion of water-soluble hexavalent chromium in the air was usually more than 50% of the total chromium concentration during welding with coated electrodes, whereas less than 10% of the chromium produced during MIG welding was in a water-soluble. Since water-soluble chromium (hexavalent) is the more important biologically, the determination of both water-soluble and water-insoluble chromium concentrations is emphasized instead of the measurement of the total concentration. The urinary chromium concentration proved to be a good indicator of short-term exposure to water-soluble chromium when exposure was above the current threshold limit value of 0.05 mg/m3, concentrations of more than 30 microgram/g of creatinine representing an exposure level higher than the threshold limit value."
14204,IARC 1980,Chromium and chromium compounds,"Chromium (VI) compounds cause mutations and allied effects; chromium (III) compounds are not mutagenic; chromosomal aberrations; chromium (III) compounds apparently cross the placenta to only a small extent; teratogenic effects; embryotoxic and teratogenic effects occurred in hamsters following exposure to chromium (VI) trioxide. Human data; an increased frequency of chromosomal aberrations has been observed in workers exposed to chromium (VI) compounds; chromate production industry; of lung cancer; workers; excess risk; highest risk occurs among workers in areas where dichromate (VI), chromium (VI) trioxide and other products are processed; ferrochromium alloys, chromium plating and chromate pigment; chromate (VI) pigment industry; lung cancer; metal alloy workers; respiratory cancers; mestotheliomas; asbestos; chromium (III) compounds; chromate production industry; cancers at all sites; oesophageal cancers; prostate cancer; macillary sinus cancers; Although the available epidemiological evidence does not permit a clear distinction between the relative carcinogenicity of chromium compounds of different oxidation states or solubilities, it appears that exposure to a mixture of chromium (VI) compounds of different solubilities (as found in the chromate production industry) carries the greatest risk to humans. There is sufficient evidence for the carcinogenicity of calcium chromate and some relatively insoluble chromium (VI) compounds (sintered calcium chromate, lead chromate, strontium chromate, sintered chromium trioxide and zinc chromate) in rats. There is limited evidence for the carcinogenicity of lead chromate (VI) oxide and cobalt-chromium alloy in rats. The data were inadequate for the evaluation of the carcinogenicity of other chromium (VI) compounds and of chromium (III) compounds (see section 4.1). There is sufficient evidence of respiratory carcinogenicity in men occupationally exposed during chromate production. Data on lung cancer risk in other chromium-associated occupations and for cancer at other sites are insufficient. The epidemiological data do not allow an evaluation of the relative contributions to carcinogenic risk of metallic chromium, chromium (III) and chromium (VI) or of soluble versus insoluble chromium compounds. (SHORTENED)","Chromium and chromium compounds Abs: Chromium (VI) compounds cause mutations and allied effects; chromium (III) compounds are not mutagenic; chromosomal aberrations; chromium (III) compounds apparently cross the placenta to only a small extent; teratogenic effects; embryotoxic and teratogenic effects occurred in hamsters following exposure to chromium (VI) trioxide. Human data; an increased frequency of chromosomal aberrations has been observed in workers exposed to chromium (VI) compounds; chromate production industry; of lung cancer; workers; excess risk; highest risk occurs among workers in areas where dichromate (VI), chromium (VI) trioxide and other products are processed; ferrochromium alloys, chromium plating and chromate pigment; chromate (VI) pigment industry; lung cancer; metal alloy workers; respiratory cancers; mestotheliomas; asbestos; chromium (III) compounds; chromate production industry; cancers at all sites; oesophageal cancers; prostate cancer; macillary sinus cancers; Although the available epidemiological evidence does not permit a clear distinction between the relative carcinogenicity of chromium compounds of different oxidation states or solubilities, it appears that exposure to a mixture of chromium (VI) compounds of different solubilities (as found in the chromate production industry) carries the greatest risk to humans. There is sufficient evidence for the carcinogenicity of calcium chromate and some relatively insoluble chromium (VI) compounds (sintered calcium chromate, lead chromate, strontium chromate, sintered chromium trioxide and zinc chromate) in rats. There is limited evidence for the carcinogenicity of lead chromate (VI) oxide and cobalt-chromium alloy in rats. The data were inadequate for the evaluation of the carcinogenicity of other chromium (VI) compounds and of chromium (III) compounds (see section 4.1). There is sufficient evidence of respiratory carcinogenicity in men occupationally exposed during chromate production. Data on lung cancer risk in other chromium-associated occupations and for cancer at other sites are insufficient. The epidemiological data do not allow an evaluation of the relative contributions to carcinogenic risk of metallic chromium, chromium (III) and chromium (VI) or of soluble versus insoluble chromium compounds. (SHORTENED)"
14201,Gomez-Arroyo et al. 1981,Sister-chromatid exchanges induced by some chromium compounds in human lymphocytes in vitro,"Treatments with various concentrations of K2Cr2O7, CaCrO4 and CrO3 were given to human lymphocytes cultured in presence of BrdUrd for 2 replicative cycles. Sister-chromatid exchanges (SCEs) were visualized by a combination of fluorescent and Giemsa techniques. In all cases, the higher the concentrations the higher the frequencies of SCEs per metaphase and per chromosome. On a concentration basis, the order of effectiveness in producing SCEs was: CaCrO4 much greater than CrO3 greater than K2Cr2O7.","Sister-chromatid exchanges induced by some chromium compounds in human lymphocytes in vitro Abs: Treatments with various concentrations of K2Cr2O7, CaCrO4 and CrO3 were given to human lymphocytes cultured in presence of BrdUrd for 2 replicative cycles. Sister-chromatid exchanges (SCEs) were visualized by a combination of fluorescent and Giemsa techniques. In all cases, the higher the concentrations the higher the frequencies of SCEs per metaphase and per chromosome. On a concentration basis, the order of effectiveness in producing SCEs was: CaCrO4 much greater than CrO3 greater than K2Cr2O7."
14188,Wahlberg and  Skog 1965,Percutaneous absorption of trivalent and hexavalent chromium: a comparative investigation in the guinea pig by means of 51Cr,"By means of an in vivo isotope technique, the so-called disappearance measurements, a comparison was made during a five-hour period between the percutaneous absorption in the guinea pig of a trivalent (chromic chloride) and a hexavalent (sodium chromate) chromium compound. Nine different concentrations of each substance were studied. We found that in the concentration interval 0.017-0.239 molar the relative absorption of the hexavalent compound was somewhat higher, but the differences were not statistically significant. On the other hand, in the higher concentrations (0.261-0.398 molar) more of the hexavalent compound was absorbed, and the differences were statistically significant. This difference in percutaneous absorption for various concentrations can perhaps account for the divergent results, in respect to the absorption of trivalent and hexavalent chromium compounds, which have recently been published.","Percutaneous absorption of trivalent and hexavalent chromium: a comparative investigation in the guinea pig by means of 51Cr Abs: By means of an in vivo isotope technique, the so-called disappearance measurements, a comparison was made during a five-hour period between the percutaneous absorption in the guinea pig of a trivalent (chromic chloride) and a hexavalent (sodium chromate) chromium compound. Nine different concentrations of each substance were studied. We found that in the concentration interval 0.017-0.239 molar the relative absorption of the hexavalent compound was somewhat higher, but the differences were not statistically significant. On the other hand, in the higher concentrations (0.261-0.398 molar) more of the hexavalent compound was absorbed, and the differences were statistically significant. This difference in percutaneous absorption for various concentrations can perhaps account for the divergent results, in respect to the absorption of trivalent and hexavalent chromium compounds, which have recently been published."
14182,Perone et al. 1974,"The chromium, cobalt, and nickel contents of American cement and their relationship to cement dermatitis","Dermatitis due to handling cement continues to be an occupational problem. This paper describes laboratory and human studies undertaken to determine the content of chromium, cobalt, and nickel in American cement samples and their etiological roles In causing dermatitis observed in cement workers in the United States.","The chromium, cobalt, and nickel contents of American cement and their relationship to cement dermatitis Abs: Dermatitis due to handling cement continues to be an occupational problem. This paper describes laboratory and human studies undertaken to determine the content of chromium, cobalt, and nickel in American cement samples and their etiological roles In causing dermatitis observed in cement workers in the United States."
14177,Sjogren et al. 1983,Urine chromium as an estimator of air exposure to stainless steel welding fumes,,Urine chromium as an estimator of air exposure to stainless steel welding fumes Abs: 
14176,Silverstein et al. 1981,Mortality among workers in a die-casting and electroplating plant,Heep copyright: biol abs. human nickel chrome poly cyclic aromatic hydro carbon lung cancer dust,Mortality among workers in a die-casting and electroplating plant Abs: Heep copyright: biol abs. human nickel chrome poly cyclic aromatic hydro carbon lung cancer dust
14175,Satoh et al. 1981,Epidemiological study of workers engaged in the manufacture of chromium compounds,"This is a study of the mortality of individuals engaged in the manufacture of chromium compounds (chromium work) at a plant in Toyko, japan, for one or more years. Morbidity data and results of liver and kidney function tests were also reviewed. The subjects of the mortality study were 896 males, who engaged in the chromium work between 1918 and 1975. Workers who died or retired or left the work for other reasons before the end of the follow-up period (1978) and for whom the necessary data were obtainable are included. When compared with Japanese males, this group of workers was found to have a standard mortality ratio for respiratory cancer of 9.2, which indicates an excess risk. No excess risk of death was indicated for cancer in other organs of the body or for other diseases. No significant differences in morbidity, which would indicate that the exposed group contracted any specific diseases, including liver and kidney disorders, more easily than did the control group, were found.","Epidemiological study of workers engaged in the manufacture of chromium compounds Abs: This is a study of the mortality of individuals engaged in the manufacture of chromium compounds (chromium work) at a plant in Toyko, japan, for one or more years. Morbidity data and results of liver and kidney function tests were also reviewed. The subjects of the mortality study were 896 males, who engaged in the chromium work between 1918 and 1975. Workers who died or retired or left the work for other reasons before the end of the follow-up period (1978) and for whom the necessary data were obtainable are included. When compared with Japanese males, this group of workers was found to have a standard mortality ratio for respiratory cancer of 9.2, which indicates an excess risk. No excess risk of death was indicated for cancer in other organs of the body or for other diseases. No significant differences in morbidity, which would indicate that the exposed group contracted any specific diseases, including liver and kidney disorders, more easily than did the control group, were found."
14172,Smith 1931,Chrome poisoning with manifestations of sensitization,"This is a case report of a patient with a history of numerous attacks of asthma and hay-fever who became acutely ill after his second exposure to ammonium-bichromate (7789095), an interval of some weeks having elapsed between the first and second exposures. The illness was characterized by skin lesions, asthma, nephritis with glycosuria, acute myositis and fever. In this case considerable importance must be attached to the part played by sensitization. Recovery followed when exposure to chromium (7440473) ceased. It is suggested that following the initial dermatitis, this patient became generally sensitized to chrome or to a tissue compound of chromium. In this case absorption of chrome was probably exclusively through the skin, as there were no lesions in the nose or throat and no digestive symptoms.","Chrome poisoning with manifestations of sensitization Abs: This is a case report of a patient with a history of numerous attacks of asthma and hay-fever who became acutely ill after his second exposure to ammonium-bichromate (7789095), an interval of some weeks having elapsed between the first and second exposures. The illness was characterized by skin lesions, asthma, nephritis with glycosuria, acute myositis and fever. In this case considerable importance must be attached to the part played by sensitization. Recovery followed when exposure to chromium (7440473) ceased. It is suggested that following the initial dermatitis, this patient became generally sensitized to chrome or to a tissue compound of chromium. In this case absorption of chrome was probably exclusively through the skin, as there were no lesions in the nose or throat and no digestive symptoms."
14166,Tsapakos et al. 1981,The carcinogen chromate induces DNA cross-links in rat liver and kidney,DNA cross-links were found in nuclei isolated from the liver and kidney of rats treated with chromate. A dose-dependent relationship between chromate exposure and total DNA cross-links was determined using the alkaline elution technique. DNA cross-links in kidney were mainly DNA- protein in nature. Chromate also induced a small amount of interstrand DNA cross-links in kidney. Liver nuclei contained protein-associated DNA single strand breaks in addition to DNA-protein cross-links. The organotropic DNA damage induced by chromate is discussed in relation to the carcinogenicity and toxicity of chromium(VI) compounds.,The carcinogen chromate induces DNA cross-links in rat liver and kidney Abs: DNA cross-links were found in nuclei isolated from the liver and kidney of rats treated with chromate. A dose-dependent relationship between chromate exposure and total DNA cross-links was determined using the alkaline elution technique. DNA cross-links in kidney were mainly DNA- protein in nature. Chromate also induced a small amount of interstrand DNA cross-links in kidney. Liver nuclei contained protein-associated DNA single strand breaks in addition to DNA-protein cross-links. The organotropic DNA damage induced by chromate is discussed in relation to the carcinogenicity and toxicity of chromium(VI) compounds.
14159,Franchini et al. 1978,Nephrotoxicity of chromium: Remarks on an experimental and epidemiological investigation,"Observations conducted on a group of workers exposed to chromium (who showed a rapid urinary excretion of the metal and progressive increase of clearance with cumulative years of exposure), induced the authors to evaluate the nephrotoxic action of chromium in rats exposed to acute and chronic intoxication. The progressive Cr accumulation in the renal cortex during the course of testing explains the increase of the excreted fraction of filtered Cr, and therefore, the clearance, of the metal through the reduction of the tubular lumen-epithelium gradient. Paralleling the anatomical lesions (demonstrated only at the level of the proximal tubular cells), are the increasing modifications of the cellular lesion or altered reabsorption registered by several urinary indicators. Similar changes were found in subjects chronically exposed to the metal; their reversibility is linked to the possibility of repairing the epithelial damage by stopping exposure.","Nephrotoxicity of chromium: Remarks on an experimental and epidemiological investigation Abs: Observations conducted on a group of workers exposed to chromium (who showed a rapid urinary excretion of the metal and progressive increase of clearance with cumulative years of exposure), induced the authors to evaluate the nephrotoxic action of chromium in rats exposed to acute and chronic intoxication. The progressive Cr accumulation in the renal cortex during the course of testing explains the increase of the excreted fraction of filtered Cr, and therefore, the clearance, of the metal through the reduction of the tubular lumen-epithelium gradient. Paralleling the anatomical lesions (demonstrated only at the level of the proximal tubular cells), are the increasing modifications of the cellular lesion or altered reabsorption registered by several urinary indicators. Similar changes were found in subjects chronically exposed to the metal; their reversibility is linked to the possibility of repairing the epithelial damage by stopping exposure."
14153,Zey and  Lucas 1985,"Health hazard evaluation report no. HETA-82-358-1558, United Catalysts, Inc. South Plant, Louisville, Kentucky","Environmental and breathing zone samples were analyzed for nickel (7440020), chromium(VI) (18540299), other metals, particulates, silica (7631869), sulfuric-acid (7664939), ammonia (7664417), and ionizing radiation at United Catalysts, Incorporated, South facility (SIC-2819), Louisville, Kentucky, in November, 1982 and Juneuly, 1983. The survey was requested by the Kentucky Department of Labor to evaluate occupational exposures and related health problems. Medical questionnaires were distributed to 98 employees. Pulmonary function test data was reviewed. All 33 personal nickel samples exceeded the NIOSH recommended standard of 15 micrograms per cubic meter (microg/m3). Four area chromium(VI) samples exceeded the NIOSH standard of 0.001microg/m3. Area ionizing radiation readings ranged up to 30 or more millirems per hour (mR/hour). The Nuclear Regulatory Commission standard for ionizing radiation is 3mR/hour. Concentrations of all other substances were below relevant standards. Sixty nine percent of the employees had one or more of such symptoms as cough, nasal sores, or skin rash. About half of the pulmonary test results were abnormal. The authors conclude that a health hazard exists due to nickel exposure. Potential hazards due to ionizing radiation and chromium(VI) also exist. Recommendations include instituting an employee education program about workplace hazards and improving respiratory protection and engineering controls.","Health hazard evaluation report no. HETA-82-358-1558, United Catalysts, Inc. South Plant, Louisville, Kentucky Abs: Environmental and breathing zone samples were analyzed for nickel (7440020), chromium(VI) (18540299), other metals, particulates, silica (7631869), sulfuric-acid (7664939), ammonia (7664417), and ionizing radiation at United Catalysts, Incorporated, South facility (SIC-2819), Louisville, Kentucky, in November, 1982 and Juneuly, 1983. The survey was requested by the Kentucky Department of Labor to evaluate occupational exposures and related health problems. Medical questionnaires were distributed to 98 employees. Pulmonary function test data was reviewed. All 33 personal nickel samples exceeded the NIOSH recommended standard of 15 micrograms per cubic meter (microg/m3). Four area chromium(VI) samples exceeded the NIOSH standard of 0.001microg/m3. Area ionizing radiation readings ranged up to 30 or more millirems per hour (mR/hour). The Nuclear Regulatory Commission standard for ionizing radiation is 3mR/hour. Concentrations of all other substances were below relevant standards. Sixty nine percent of the employees had one or more of such symptoms as cough, nasal sores, or skin rash. About half of the pulmonary test results were abnormal. The authors conclude that a health hazard exists due to nickel exposure. Potential hazards due to ionizing radiation and chromium(VI) also exist. Recommendations include instituting an employee education program about workplace hazards and improving respiratory protection and engineering controls."
14149,Yamaguchi et al. 1983,On the biological half-time of hexavalent chromium in rats,HEEP COPYRIGHT: BIOL ABS. RRM,On the biological half-time of hexavalent chromium in rats Abs: HEEP COPYRIGHT: BIOL ABS. RRM
14147,Welinder et al. 1983,Elimination of chromium in urine after stainless steel welding,"Nine retired (on an average of four years) stainless steel welders had higher (p less than 0.001) urinary chromium levels [mean 7 (range 3-13) mumol/mol of creatinine] than 21 nonexposed referents [mean less than or equal to 1.5 (range less than 0.6-7) mumol/mol of creatinine] but did not differ in this respect from 14 active welders studied at the end of a 31-d vacation (mean 9, range 4-17). This result shows the existence of a slow compartment for chromium in the body. Urinary chromium on time after the end of exposure was analyzed mathematically by use of an exponential two-compartment model. Good fits were obtained, showing the existence of a fast compartment in addition to the slow one. For four welders followed for 31 d, the biological half-time of the slow compartment ranged from 14 d to infinity. For 12 welders followed for 60 h, the fast compartment had a median half-time of 7 (range 4-35) h. For 19 welders there was a significant (p less than 0.01) correlation between chromium in air (total and soluble hexavalent) and urinary chromium (rs = 0.68 and 0.64). However, the variation of urinary chromium on chromium in air was considerable, especially at chromium air levels at or below the hygienic standards. Correction for urinary chromium levels on Monday morning did not decrease the variation.","Elimination of chromium in urine after stainless steel welding Abs: Nine retired (on an average of four years) stainless steel welders had higher (p less than 0.001) urinary chromium levels [mean 7 (range 3-13) mumol/mol of creatinine] than 21 nonexposed referents [mean less than or equal to 1.5 (range less than 0.6-7) mumol/mol of creatinine] but did not differ in this respect from 14 active welders studied at the end of a 31-d vacation (mean 9, range 4-17). This result shows the existence of a slow compartment for chromium in the body. Urinary chromium on time after the end of exposure was analyzed mathematically by use of an exponential two-compartment model. Good fits were obtained, showing the existence of a fast compartment in addition to the slow one. For four welders followed for 31 d, the biological half-time of the slow compartment ranged from 14 d to infinity. For 12 welders followed for 60 h, the fast compartment had a median half-time of 7 (range 4-35) h. For 19 welders there was a significant (p less than 0.01) correlation between chromium in air (total and soluble hexavalent) and urinary chromium (rs = 0.68 and 0.64). However, the variation of urinary chromium on chromium in air was considerable, especially at chromium air levels at or below the hygienic standards. Correction for urinary chromium levels on Monday morning did not decrease the variation."
14145,Petrilli and  De Flora 1982,Interpretations on chromium mutagenicity and carcinogenicity,,Interpretations on chromium mutagenicity and carcinogenicity Abs: 
14141,van der Wal 1985,"Exposure of welders to fumes, Cr, Ni, Cu and gases in Dutch industries","Exposures to total particulate, chromium (7440473), nickel (7440020), and copper (7440508) fumes during the welding of non alloyed, stainless, and high alloyed steels were investigated in welders. Exposure to nitrogen oxides and ozone was also monitored. The techniques investigated included: welding stainless steel using manual metal arc with coated electrodes, metal inert gas, and tungsten inert gas; welding alloys with tungsten inert gas; aluminum bronze with metal inert gas; and manual metal arc and tungsten inert gas welding. Samples were collected in the breathing zone of the welders behind the face guard. Samples were also collected at about 2 meters distance from the welders and their working areas. Samples were analyzed by atomic absorption spectrometry for content of particulate and metals in the particulate fume. Manual metal arc welding fumes of stainless steel contained soluble hexavalent chromium. During metal inert gas and tungsten inert gas welding, the fumes contained chromium which was insoluble in water and not hexavalent. The nickel was insoluble in water in all three processes. Only metal inert gas welding of aluminum yielded concentrations of ozone in the breathing zone exceeding permissible standards. The author concludes that exposure to copper, nickel, and chromium fumes during welding may exceed occupational safety standards.","Exposure of welders to fumes, Cr, Ni, Cu and gases in Dutch industries Abs: Exposures to total particulate, chromium (7440473), nickel (7440020), and copper (7440508) fumes during the welding of non alloyed, stainless, and high alloyed steels were investigated in welders. Exposure to nitrogen oxides and ozone was also monitored. The techniques investigated included: welding stainless steel using manual metal arc with coated electrodes, metal inert gas, and tungsten inert gas; welding alloys with tungsten inert gas; aluminum bronze with metal inert gas; and manual metal arc and tungsten inert gas welding. Samples were collected in the breathing zone of the welders behind the face guard. Samples were also collected at about 2 meters distance from the welders and their working areas. Samples were analyzed by atomic absorption spectrometry for content of particulate and metals in the particulate fume. Manual metal arc welding fumes of stainless steel contained soluble hexavalent chromium. During metal inert gas and tungsten inert gas welding, the fumes contained chromium which was insoluble in water and not hexavalent. The nickel was insoluble in water in all three processes. Only metal inert gas welding of aluminum yielded concentrations of ozone in the breathing zone exceeding permissible standards. The author concludes that exposure to copper, nickel, and chromium fumes during welding may exceed occupational safety standards."
14133,Tandon et al. 1978,Comparative toxicity of trivalent and hexavalent chromium: Alterations in blood and liver,"The effects of trivalent and hexavalent chromium compounds on rabbits were studied with a view toward investigating the toxic potentials of two different forms of chromium to which industrial workers or miners might be exposed. While both forms of chromium altered the levels of certain important chemical constituents of blood and serum and produced significant morphological changes in the liver, the hexavalent form induced a greater effect. The accumulation of the metal was also higher in animals exposed to chromium in oxidation state 6 than in those exposed to metal in state 3.","Comparative toxicity of trivalent and hexavalent chromium: Alterations in blood and liver Abs: The effects of trivalent and hexavalent chromium compounds on rabbits were studied with a view toward investigating the toxic potentials of two different forms of chromium to which industrial workers or miners might be exposed. While both forms of chromium altered the levels of certain important chemical constituents of blood and serum and produced significant morphological changes in the liver, the hexavalent form induced a greater effect. The accumulation of the metal was also higher in animals exposed to chromium in oxidation state 6 than in those exposed to metal in state 3."
14131,Suzuki and  Wada 1982,A comparative study of metal transport systems in mouse liver,"HEEP COPYRIGHT: BIOL ABS. To investigate intracellular metal transport systems in the liver in vivo, male mice were given a single i.p. dose of Mn(CH3COO)2 4H2O (49 mg/kg), CuSO4 5H2O (6 mg/kg), K2Cr2O7 (15 mg/kg) or Pb(CH3COO)2 3H2O (38 mg/kg). High concentrations of Mn in the liver were rapidly recovered in lysosomal and mitochondrial fractions and seemed to be excreted into bile via liver lysosomes. The normal distribution of Ca in the subcellular fractions and bile was similar to that of excessive Mn. Following injection of Mn, Ca content in the liver mitochondria increased but decreased in bile. Absorbed Cu, Pb, Cr and normal Zn in the liver were mainly recovered in the soluble fraction. Most absorbed Cu, Pb and normal Zn in the soluble fraction was bound to high MW substances; most excessive Cr was bound to a low MW substance. Cr content decreased more rapidly than Cu and Pb content in the soluble fraction. Metal concentrations recovered in the liver lysosomes and excreted in bile were in the following order: Ca, Mn Zn, Cu Cr, Pb. Biliary excretion of these metals, especially Mn and Ca, primarily depended on lysosomal metal uptake and release, and the nature of metal binding substances for Cu, Pb, Cr and Zn affected their transport systems in liver.","A comparative study of metal transport systems in mouse liver Abs: HEEP COPYRIGHT: BIOL ABS. To investigate intracellular metal transport systems in the liver in vivo, male mice were given a single i.p. dose of Mn(CH3COO)2 4H2O (49 mg/kg), CuSO4 5H2O (6 mg/kg), K2Cr2O7 (15 mg/kg) or Pb(CH3COO)2 3H2O (38 mg/kg). High concentrations of Mn in the liver were rapidly recovered in lysosomal and mitochondrial fractions and seemed to be excreted into bile via liver lysosomes. The normal distribution of Ca in the subcellular fractions and bile was similar to that of excessive Mn. Following injection of Mn, Ca content in the liver mitochondria increased but decreased in bile. Absorbed Cu, Pb, Cr and normal Zn in the liver were mainly recovered in the soluble fraction. Most absorbed Cu, Pb and normal Zn in the soluble fraction was bound to high MW substances; most excessive Cr was bound to a low MW substance. Cr content decreased more rapidly than Cu and Pb content in the soluble fraction. Metal concentrations recovered in the liver lysosomes and excreted in bile were in the following order: Ca, Mn Zn, Cu Cr, Pb. Biliary excretion of these metals, especially Mn and Ca, primarily depended on lysosomal metal uptake and release, and the nature of metal binding substances for Cu, Pb, Cr and Zn affected their transport systems in liver."
14130,Suzuki et al. 1984,Distribution of chromium in rats exposed to hexavalent chromium and trivalent chromium aerosols,"Retention and clearance of chromium in the lung, heart, liver, kidney, spleen, plasma and blood cells were investigated in rats after a single exposure to either hexavalent chromium (Cr (VI)) or trivalent chromium (Cr (III)) aerosols with different chromium levels (7.415.9 mg Cr/m3) and different particle size distributions. The investigation was carried out from 0.5 h up to 7 days after exposure. Exposure to Cr (VI) aerosol showed more toxic effects than exposure to Cr (III). Initial cocentrations of lung chromium were in proportion to the exposure levels for each inhalation series of Cr (VI) or Cr (III) compounds. Chromium clearance from the lungs in the Cr (VI) groups was dependent on the size distribution of the aerosol particles. In the groups exposed to smaller Cr (VI) aerosol particles the lung chromium clearance showed two phases. The biological half-time of the first phase was 31.5 h and that of the following second phase was 732 h. Chromium clearance from lungs exposed to larger particles of Cr (VI) or to Cr (III) aerosols showed a single phase, the biological half-time of which ranged from 151 to 175 h. Chromium transport from the lungs into the blood, kidneys and liver was more rapid in the Cr (VI) groups than in the Cr (III) groups. In the former groups, the kidneys and liver also showed two-phase chromium clearance. These results suggest that considerable amount of chromium deposited in lung alveoli as the hexavalent form are rapidly transfered into the blood and taken up by erythrocytes or visceral organs, especially the liver and kidneys, before being reduced to the trivalent state.","Distribution of chromium in rats exposed to hexavalent chromium and trivalent chromium aerosols Abs: Retention and clearance of chromium in the lung, heart, liver, kidney, spleen, plasma and blood cells were investigated in rats after a single exposure to either hexavalent chromium (Cr (VI)) or trivalent chromium (Cr (III)) aerosols with different chromium levels (7.415.9 mg Cr/m3) and different particle size distributions. The investigation was carried out from 0.5 h up to 7 days after exposure. Exposure to Cr (VI) aerosol showed more toxic effects than exposure to Cr (III). Initial cocentrations of lung chromium were in proportion to the exposure levels for each inhalation series of Cr (VI) or Cr (III) compounds. Chromium clearance from the lungs in the Cr (VI) groups was dependent on the size distribution of the aerosol particles. In the groups exposed to smaller Cr (VI) aerosol particles the lung chromium clearance showed two phases. The biological half-time of the first phase was 31.5 h and that of the following second phase was 732 h. Chromium clearance from lungs exposed to larger particles of Cr (VI) or to Cr (III) aerosols showed a single phase, the biological half-time of which ranged from 151 to 175 h. Chromium transport from the lungs into the blood, kidneys and liver was more rapid in the Cr (VI) groups than in the Cr (III) groups. In the former groups, the kidneys and liver also showed two-phase chromium clearance. These results suggest that considerable amount of chromium deposited in lung alveoli as the hexavalent form are rapidly transfered into the blood and taken up by erythrocytes or visceral organs, especially the liver and kidneys, before being reduced to the trivalent state."
14122,Stephenson and  Cherniak 1984,"Health hazard evaluation report no. HETA-81-434-1404, Empire-Detroit Steel Division, Mansfield, Ohio","Worker exposures to metal dust and fumes and to oil mist were investigated on September 15 to 17 and December 1 and 2, 1982 at Empireetroit Steel Division (SIC-3312) in Mansfield, Ohio. The evaluation was requested by a group of employees on behalf of about 120 workers assigned to the hot strip mill operations. Medical questionnaires were given to 47 male workers, and area and personal air samples were analyzed for chromium (7440473), hexavalent chromium (18540299), iron-oxide (1332372) fumes, nickel (7440020), oil mist, respirable particulates, and total particulates. Irritation of the eyes and upper respiratory system was reported by 47 percent of the workers, and symptom prevalence was related to work in dusty areas. Recurrent cough, chronic bronchitis, and respiratory disease subsequent to initial employment at the factory were also frequently reported. Nineteen workers reported recurrent episodes of tinnitus. Of the environmental contaminants, only hexavalent chromium was found in concentrations that exceeded its OSHA limit of 0.1 milligram per cubic meter. The authors conclude that a health hazard exists from exposure to hexavalent chromium. They recommend engineering controls, environmental monitoring, medical surveillance, and use of safety glasses and hearing protection devices to reduce and control workplace hazards.","Health hazard evaluation report no. HETA-81-434-1404, Empire-Detroit Steel Division, Mansfield, Ohio Abs: Worker exposures to metal dust and fumes and to oil mist were investigated on September 15 to 17 and December 1 and 2, 1982 at Empireetroit Steel Division (SIC-3312) in Mansfield, Ohio. The evaluation was requested by a group of employees on behalf of about 120 workers assigned to the hot strip mill operations. Medical questionnaires were given to 47 male workers, and area and personal air samples were analyzed for chromium (7440473), hexavalent chromium (18540299), iron-oxide (1332372) fumes, nickel (7440020), oil mist, respirable particulates, and total particulates. Irritation of the eyes and upper respiratory system was reported by 47 percent of the workers, and symptom prevalence was related to work in dusty areas. Recurrent cough, chronic bronchitis, and respiratory disease subsequent to initial employment at the factory were also frequently reported. Nineteen workers reported recurrent episodes of tinnitus. Of the environmental contaminants, only hexavalent chromium was found in concentrations that exceeded its OSHA limit of 0.1 milligram per cubic meter. The authors conclude that a health hazard exists from exposure to hexavalent chromium. They recommend engineering controls, environmental monitoring, medical surveillance, and use of safety glasses and hearing protection devices to reduce and control workplace hazards."
14118,Stella et al. 1982,Clastogenic effects of chromium on human lymphocytes in vitro and in vivo,"The induction of SCEs and chromosome aberrations in PHA-stimulated human lymphocytes treated in vitro for 70 h with Cr(VI) (potassium dichromate, K2Cr2O7) or Cr(III) (chromium chloride, CrCl3) was determined. A clear dose-dependent increase of the frequency of SCEs is induced by Cr(VI), a 2.5-fold increase being obtained with 10?5 M K2Cr2O7. Cr(III) is, on the other hand, absolutely inactive even when used at sub-toxic concentrations (10?3 M CrCl3). The overall frequency of chromosome aberrations is significantly increased by Cr(VI) above 2.5 × 10?7 M K2Cr2O7, and chromatid-type aberrations (gaps and breaks) are the most frequent. 100 times higher concentrations of CrCl3 are required to increase the frequency of chromosome aberrations. A difference of the same order of magnitude is observed for the cytotoxic activity of Cr(VI) and Cr(III), which is characterized by a slowing down of the mitotic cycle reflected by increased 1st-division and decreased 3rd-division metaphases. By treating unstimulated lymphocytes in vitro with Cr(VI) in the G0 phase, an increase in the frequency of SCEs is produced significantly lower than that obtained on stimulated lymphocytes. Cr(VI) treatments performed at different intervals after stimulation show that the sensitivity of lymphocytes to the induction of SCEs by CR(VI) depends on the phase of the cell cycle, highest frequencies of SCEs being obtained when the cells enter the S phase of DNA replication. The frequency of SCEs in lymphocytes of 12 workers exposed to Cr(VI) (chromic acid fumes in a plating works) is significantly higher than that of 10 control donors. In particular, all the 7 youngest workers, although the most recently engaged in chromium plating, show significantly increased SCE frequencies.","Clastogenic effects of chromium on human lymphocytes in vitro and in vivo Abs: The induction of SCEs and chromosome aberrations in PHA-stimulated human lymphocytes treated in vitro for 70 h with Cr(VI) (potassium dichromate, K2Cr2O7) or Cr(III) (chromium chloride, CrCl3) was determined. A clear dose-dependent increase of the frequency of SCEs is induced by Cr(VI), a 2.5-fold increase being obtained with 10?5 M K2Cr2O7. Cr(III) is, on the other hand, absolutely inactive even when used at sub-toxic concentrations (10?3 M CrCl3). The overall frequency of chromosome aberrations is significantly increased by Cr(VI) above 2.5 × 10?7 M K2Cr2O7, and chromatid-type aberrations (gaps and breaks) are the most frequent. 100 times higher concentrations of CrCl3 are required to increase the frequency of chromosome aberrations. A difference of the same order of magnitude is observed for the cytotoxic activity of Cr(VI) and Cr(III), which is characterized by a slowing down of the mitotic cycle reflected by increased 1st-division and decreased 3rd-division metaphases. By treating unstimulated lymphocytes in vitro with Cr(VI) in the G0 phase, an increase in the frequency of SCEs is produced significantly lower than that obtained on stimulated lymphocytes. Cr(VI) treatments performed at different intervals after stimulation show that the sensitivity of lymphocytes to the induction of SCEs by CR(VI) depends on the phase of the cell cycle, highest frequencies of SCEs being obtained when the cells enter the S phase of DNA replication. The frequency of SCEs in lymphocytes of 12 workers exposed to Cr(VI) (chromic acid fumes in a plating works) is significantly higher than that of 10 control donors. In particular, all the 7 youngest workers, although the most recently engaged in chromium plating, show significantly increased SCE frequencies."
14116,Srivastava et al. 1985,Comparative toxicity of trivalent and hexavalent chromium V: enzymatic alterations in rat liver and kidneys,"The metabolic alterations caused by trivalent-chromium (16065831) and hexavalent-chromium (18540299) were studied in rat liver and kidneys. Male albino-rats were injected with either trivalent chromium-nitrate (13548384) or hexavalent potassium-chromate (7789006) at 4 milligrams per kilogram intraperitoneally, daily for 2 weeks. Control rats received saline only. The rats were sacrificed; liver and kidneys were removed and homogenized; and microsomal fractions were prepared. A portion of the homogenate was used to measure chromium content. Blood was sampled, and chromium content in blood was determined. Activities of transaminases, acid-phosphatase, lactic-dehydrogenase, aniline-hydroxylase, aminopyrine-N-demethylase, and glutathione-S-transferase in the microsomal fraction were determined. Chromium content of tissues was determined by atomic absorption spectrophotometry. The results were analyzed for statistical significance. The activity of liver aniline-hydroxylase decreased significantly on days 7 and 14 after chromium exposure; the activity of aminopyrine-N-demethylase decreased only on day 14 after exposure. The chromium valence state did not influence these changes in enzyme activity. Glutathione-S-transferase decreased after hexavalent-chromium exposure on day 1 and continued to decrease thereafter; with trivalent-chromium, inhibition of this enzyme could be discerned only on day 14. Activities of transaminases, lactic-dehydrogenase, and acid-phosphatase decreased significantly after trivalent-chromium exposure, whereas hexavalent-chromium exposure was without effect. The liver content of chromium increased on day 7 and 14 after exposure to trivalent or hexavalent state compounds, whereas the kidney content increased significantly on day 14 only. The concentration of chromium in blood increased steadily from day 1 onward irrespective of the valence state of the metal. The authors conclude that water soluble chromium compounds may have toxic potential irrespective of the valence state.","Comparative toxicity of trivalent and hexavalent chromium V: enzymatic alterations in rat liver and kidneys Abs: The metabolic alterations caused by trivalent-chromium (16065831) and hexavalent-chromium (18540299) were studied in rat liver and kidneys. Male albino-rats were injected with either trivalent chromium-nitrate (13548384) or hexavalent potassium-chromate (7789006) at 4 milligrams per kilogram intraperitoneally, daily for 2 weeks. Control rats received saline only. The rats were sacrificed; liver and kidneys were removed and homogenized; and microsomal fractions were prepared. A portion of the homogenate was used to measure chromium content. Blood was sampled, and chromium content in blood was determined. Activities of transaminases, acid-phosphatase, lactic-dehydrogenase, aniline-hydroxylase, aminopyrine-N-demethylase, and glutathione-S-transferase in the microsomal fraction were determined. Chromium content of tissues was determined by atomic absorption spectrophotometry. The results were analyzed for statistical significance. The activity of liver aniline-hydroxylase decreased significantly on days 7 and 14 after chromium exposure; the activity of aminopyrine-N-demethylase decreased only on day 14 after exposure. The chromium valence state did not influence these changes in enzyme activity. Glutathione-S-transferase decreased after hexavalent-chromium exposure on day 1 and continued to decrease thereafter; with trivalent-chromium, inhibition of this enzyme could be discerned only on day 14. Activities of transaminases, lactic-dehydrogenase, and acid-phosphatase decreased significantly after trivalent-chromium exposure, whereas hexavalent-chromium exposure was without effect. The liver content of chromium increased on day 7 and 14 after exposure to trivalent or hexavalent state compounds, whereas the kidney content increased significantly on day 14 only. The concentration of chromium in blood increased steadily from day 1 onward irrespective of the valence state of the metal. The authors conclude that water soluble chromium compounds may have toxic potential irrespective of the valence state."
14114,Siegenthaler et al. 1983,Studies on contact sensitivity to chromium in the guinea pig The role of valence in the formation of the antigenic determinant,Guinea pigs sensitized with either the trivalent chromium chloride or the hexavalent potassium dichromate are capable of reacting in vivo and in vitro to challenges with both chromium salts. This double reactivity is retained also after repeated restimulations with only 1 of these chromium compounds. From the failure to select lymphocytes directed specifically against a chromium determinant of a particular valence it is concluded that by sensitization with chromium salts of different valences a common determinant or closely related determinants are formed. It is suggested that this determinant is formed by chromium in the trivalent form.,Studies on contact sensitivity to chromium in the guinea pig The role of valence in the formation of the antigenic determinant Abs: Guinea pigs sensitized with either the trivalent chromium chloride or the hexavalent potassium dichromate are capable of reacting in vivo and in vitro to challenges with both chromium salts. This double reactivity is retained also after repeated restimulations with only 1 of these chromium compounds. From the failure to select lymphocytes directed specifically against a chromium determinant of a particular valence it is concluded that by sensitization with chromium salts of different valences a common determinant or closely related determinants are formed. It is suggested that this determinant is formed by chromium in the trivalent form.
14110,Sayato et al. 1980,Metabolic fate of chromium compounds. I. Comparative behavior of chromium in rat administered with Na251CrO4 and 51CrCl3,"Comparative metabolic fate of labelled chromium chloride and sodium chromate and interaction of these compounds in the rat liver and blood were investigated after their oral and intravenous administration. Gastrointestinal absorption of both compounds was below 1% of the oral dose, but trivalent chromium showed higher radioactivity than the hexavalent form in rats (biological half-life: CrCl3 91.79 days, Na2CrO4 22.24 days). The higher residual activity of the trivalent chromium was also observed after intravenous administration. Both forms of chromium were excreted more in the urine via the kidney than in the intestinal tract after intravenous administration. When 51CrCl3 and Na251CrO4 were injected into rats, in the time-distribution patterns of 51Cr in the organs, a significant difference was shown between oxidation states of the two compounds, especially in subcellular fractions of the liver and blood constituents. This significant difference mainly observed in the rat blood came from the fact that trivalent chromium possessed a high binding activity for transferrin in plasma, while hexavalent chromium was permeable into red cells and bound with hemoglobin.","Metabolic fate of chromium compounds. I. Comparative behavior of chromium in rat administered with Na251CrO4 and 51CrCl3 Abs: Comparative metabolic fate of labelled chromium chloride and sodium chromate and interaction of these compounds in the rat liver and blood were investigated after their oral and intravenous administration. Gastrointestinal absorption of both compounds was below 1% of the oral dose, but trivalent chromium showed higher radioactivity than the hexavalent form in rats (biological half-life: CrCl3 91.79 days, Na2CrO4 22.24 days). The higher residual activity of the trivalent chromium was also observed after intravenous administration. Both forms of chromium were excreted more in the urine via the kidney than in the intestinal tract after intravenous administration. When 51CrCl3 and Na251CrO4 were injected into rats, in the time-distribution patterns of 51Cr in the organs, a significant difference was shown between oxidation states of the two compounds, especially in subcellular fractions of the liver and blood constituents. This significant difference mainly observed in the rat blood came from the fact that trivalent chromium possessed a high binding activity for transferrin in plasma, while hexavalent chromium was permeable into red cells and bound with hemoglobin."
14104,Miyamoto et al. 1975,Delayed-type hypersensitivity reaction in the lungs of guinea pigs due to potassium dichromate,"Potassium dichromate was inhaled by guinea pigs previously immunized by potassium dichromate until strong positive patch tests were obtained. No obvious respiratory changes were noted during and after inhalation. Histologically, however, mononuclear cells infiltrated the interstitial spaces in large areas of the lung, producing considerable thickening of the alveolar spaces in 24 to 48 hr after inhalation. Polymorphonuclear cells were predominant initially. These changes were similar to the delayed-type hypersensitivity reaction in the lung elicited by the inhalation of purified protein derivative (PPD) in the guinea pigs immunized by an injection of dry-killed tubercle bacilli. A less marked reaction was observed in guinea pigs passively sensitized with peritoneal exudate cells and lymph node cells. Consequently, the pulmonary changes were thought to be elicited by delayed-type hypersensitivity reaction due to a simple chemical. The clinical implications of delayed-type hypersensitivity reaction in the lung due to simple chemicals are discussed.","Delayed-type hypersensitivity reaction in the lungs of guinea pigs due to potassium dichromate Abs: Potassium dichromate was inhaled by guinea pigs previously immunized by potassium dichromate until strong positive patch tests were obtained. No obvious respiratory changes were noted during and after inhalation. Histologically, however, mononuclear cells infiltrated the interstitial spaces in large areas of the lung, producing considerable thickening of the alveolar spaces in 24 to 48 hr after inhalation. Polymorphonuclear cells were predominant initially. These changes were similar to the delayed-type hypersensitivity reaction in the lung elicited by the inhalation of purified protein derivative (PPD) in the guinea pigs immunized by an injection of dry-killed tubercle bacilli. A less marked reaction was observed in guinea pigs passively sensitized with peritoneal exudate cells and lymph node cells. Consequently, the pulmonary changes were thought to be elicited by delayed-type hypersensitivity reaction due to a simple chemical. The clinical implications of delayed-type hypersensitivity reaction in the lung due to simple chemicals are discussed."
14103,Wiegand et al. 1984,Disposition of intratracheally administered chromium(III) and chromium(VI) in rabbits,"Intratracheal instillation of 51CrCl3 in anaesthetized rabbits resulted in partial absorption. In blood, the absorbed material was entirely confined to the plasma compartment. Only trace amounts were deposited in liver and kidney. By contrast, after similar application of Na(2)51CrO4 the bulk of blood radioactivity was present in erythrocytes. Substantial deposition occurred in liver and kidneys. It is concluded that Cr(VI) may enter the body unreduced via the lung and is partly deposited in cells over a prolonged period of time.","Disposition of intratracheally administered chromium(III) and chromium(VI) in rabbits Abs: Intratracheal instillation of 51CrCl3 in anaesthetized rabbits resulted in partial absorption. In blood, the absorbed material was entirely confined to the plasma compartment. Only trace amounts were deposited in liver and kidney. By contrast, after similar application of Na(2)51CrO4 the bulk of blood radioactivity was present in erythrocytes. Substantial deposition occurred in liver and kidneys. It is concluded that Cr(VI) may enter the body unreduced via the lung and is partly deposited in cells over a prolonged period of time."
14096,Petrilli and  De Flora 1978,Oxidation of inactive trivalent chromium to the mutagenic hexavalent form,"Soluble trivalent chromium compounds (chromium potassium sulfate, chromium nitrate, chromium chloride, neochromium and chromium alum) were inactive for Salmonella typhimurium TA100, even at milligram amounts per plate. No effect could be detected either in the absence or in the presence of rat-liver, lung or muscle microsomal fractions, of rat-muscle mitochondria (with or without ATP), of oxidized glutathione (GSSG), or of human serum, plasma or erythrocyte lysates. Conversely, addition of a strongly oxidizing agent (potassium permanganate) resulted in toxic effects in plates incorporating more than 40--80 microgram of compounds and elicited a dose-effect mutagenic response at 10--40 microgram per plate. These effects could be ascribed to oxidation of chromium from the trivalent to the active hexavalent state. Insoluble chromite, as tested in the spot test, was spontaneously mutagenic, owing to contamination of the industrial product with hexavalent chromium. The results obtained may be useful to interpret the findings of carcinogenicity tests and to predict health hazards linked to chromium.","Oxidation of inactive trivalent chromium to the mutagenic hexavalent form Abs: Soluble trivalent chromium compounds (chromium potassium sulfate, chromium nitrate, chromium chloride, neochromium and chromium alum) were inactive for Salmonella typhimurium TA100, even at milligram amounts per plate. No effect could be detected either in the absence or in the presence of rat-liver, lung or muscle microsomal fractions, of rat-muscle mitochondria (with or without ATP), of oxidized glutathione (GSSG), or of human serum, plasma or erythrocyte lysates. Conversely, addition of a strongly oxidizing agent (potassium permanganate) resulted in toxic effects in plates incorporating more than 40--80 microgram of compounds and elicited a dose-effect mutagenic response at 10--40 microgram per plate. These effects could be ascribed to oxidation of chromium from the trivalent to the active hexavalent state. Insoluble chromite, as tested in the spot test, was spontaneously mutagenic, owing to contamination of the industrial product with hexavalent chromium. The results obtained may be useful to interpret the findings of carcinogenicity tests and to predict health hazards linked to chromium."
14095,Petrilli et al. 1985,Specificity and inducibility of the metabolic reduction of chromium(VI) mutagenicity by subcellular fractions of rat tissues,"#The mutagenicity of sodium dichromate in the Ames test was decreased as a consequence of chromium(VI) reduction by tissue postmitochondrial (S-9 or S-12) fractions from untreated rats with the following rank of efficiency: liver; kidney; and lung. The effects of lung preparations were significantly enhanced following the intratracheal administration of high doses (0.25 mg/kg) of dichromate itself, 5 times per week for 4 weeks (i.e., 20 fractionated instillations). No changes were conversely detected following single weekly doses of 1.25 mg/kg for the same period (i.e., four cumulative instillations). The local stimulation of chromium(VI) metabolism was also confirmed by testing the mutagenicity of calcium chromate and chromium trioxide, whereas the metabolism of a number of other activatable or deactivatable mutagens was not significantly affected by intratracheal treatment with chromium(VI). Of three enzyme inducers injected i.p. which modified the spectral properties and/or concentration of cytochromes P-450 in liver and lung microsomes, only Aroclor 1254 proved to stimulate chromium(VI) metabolism in lung cells. In liver cells, Aroclor 1254 and to a lower extent phenobarbital induced chromium(VI) reduction, while 3-methylcholanthrene was ineffective. Pretreatment of rats with these three compounds resulted in a selective induction of the metabolic activation of promutagens [benzo(a)pyrene and its trans-7,8-diol, 2-aminofluorene, aflatoxin B1] and of the metabolic deactivation of direct-acting mutagens {2-methoxy-6-chloro-9-[3-(2-chloroethyl)-aminopropylamino]acridineÀ2HCl, epichlorohydrin, 4-nitroquinolino-N-oxide} by S-12 and microsomal fractions. These findings indicate that, in addition to already recognized detoxification mechanisms operating outside target cells (26), specific and inducible chromium-reducing pathways, mediating threshold phenomena in chromium carcinogenesis, do also occur in the intracellular environment.","Specificity and inducibility of the metabolic reduction of chromium(VI) mutagenicity by subcellular fractions of rat tissues Abs: #The mutagenicity of sodium dichromate in the Ames test was decreased as a consequence of chromium(VI) reduction by tissue postmitochondrial (S-9 or S-12) fractions from untreated rats with the following rank of efficiency: liver; kidney; and lung. The effects of lung preparations were significantly enhanced following the intratracheal administration of high doses (0.25 mg/kg) of dichromate itself, 5 times per week for 4 weeks (i.e., 20 fractionated instillations). No changes were conversely detected following single weekly doses of 1.25 mg/kg for the same period (i.e., four cumulative instillations). The local stimulation of chromium(VI) metabolism was also confirmed by testing the mutagenicity of calcium chromate and chromium trioxide, whereas the metabolism of a number of other activatable or deactivatable mutagens was not significantly affected by intratracheal treatment with chromium(VI). Of three enzyme inducers injected i.p. which modified the spectral properties and/or concentration of cytochromes P-450 in liver and lung microsomes, only Aroclor 1254 proved to stimulate chromium(VI) metabolism in lung cells. In liver cells, Aroclor 1254 and to a lower extent phenobarbital induced chromium(VI) reduction, while 3-methylcholanthrene was ineffective. Pretreatment of rats with these three compounds resulted in a selective induction of the metabolic activation of promutagens [benzo(a)pyrene and its trans-7,8-diol, 2-aminofluorene, aflatoxin B1] and of the metabolic deactivation of direct-acting mutagens {2-methoxy-6-chloro-9-[3-(2-chloroethyl)-aminopropylamino]acridineÀ2HCl, epichlorohydrin, 4-nitroquinolino-N-oxide} by S-12 and microsomal fractions. These findings indicate that, in addition to already recognized detoxification mechanisms operating outside target cells (26), specific and inducible chromium-reducing pathways, mediating threshold phenomena in chromium carcinogenesis, do also occur in the intracellular environment."
14094,De Flora et al. 1985,Prominent role of DT-diaphorase as a cellular mechanism reducing chromium(VI) and reverting its mutagenicity,"Rat liver postmitochondrial (S-12) fractions accounted for the bulk of the activity of whole cell homogenates in reducing chromium(VI) and accordingly in decreasing its mutagenicity. Both cytosolic (S-105) and microsomal fractions concurred to this process, which in all subcellular preparations tested was selectively induced by phenobarbital and especially by Aroclor 1254, but not by 3-methylcholanthrene. Cytosolic fractions were markedly more efficient in reducing chromium(VI) than microsomal fractions recovered from the same amount of tissue (liver or lung), although the latter preparations had a higher specific activity. The microsomal activity was exclusively NADPH dependent. A minor part of the cytosolic reduction was determined by nonenzymatic components, notably by some electron donors and chiefly by reduced glutathione, which proved to reduce chromium(VI) at physiological concentrations. However, also in cytosolic fractions, the most important contribution to chromium reduction was enzyme catalyzed, as shown by the following properties: thermolability; requirement for exogenous NADH or NADPH [supplied as such or in the form of a NADPH-generating system (S-9 mix)]; and saturation by chromium(VI). The likely involvement of DT-diaphorase in this metabolic process is supported by several findings, including its sharp pH dependence and its partial suppression by known inhibitors of this enzyme protein, such as p-chloromercuribenzoate, L-thyroxine, and dicumarol (which conversely did not counteract the metabolic deactivation of the other direct-acting mutagens 2-methoxy-6-chloro-9-[3-(2-chloroethyl)aminopropylamino]acridine 2HCl and epichlorohydrin). Similarly, cytosolic reduction of chromium(VI) was partially inhibited by selective metabolic depletors of both coenzymes of DT-diaphorase, i.e., NADPH and NADH. Pretreatment of rats with enzyme inducers (phenobarbital and 3-methylcholanthrene) stimulated the activity of DT-diaphorase in liver cytosolic fractions. A dramatic stimulation (35 to 40 times over untreated controls) was produced by Aroclor 1254, which also coinduced the liver cytosolic activity of enzymes involved in the glucose 6-phosphate-dependent pathway of both nicotinamideadenine-dinucleotide phosphate and glutathione reduction (glucose-6-phosphate dehydrogenase, 6-phosphogluconate dehydrogenase, and glutathione reductase). In the lung cytosol, a slight yet significant stimulation of some of these enzyme activities was determined by the daily intratracheal instillations of high doses of chromium(VI) itself for 4 weeks, a condition which has been found to enhance the pulmonary metabolism of this metal ion.","Prominent role of DT-diaphorase as a cellular mechanism reducing chromium(VI) and reverting its mutagenicity Abs: Rat liver postmitochondrial (S-12) fractions accounted for the bulk of the activity of whole cell homogenates in reducing chromium(VI) and accordingly in decreasing its mutagenicity. Both cytosolic (S-105) and microsomal fractions concurred to this process, which in all subcellular preparations tested was selectively induced by phenobarbital and especially by Aroclor 1254, but not by 3-methylcholanthrene. Cytosolic fractions were markedly more efficient in reducing chromium(VI) than microsomal fractions recovered from the same amount of tissue (liver or lung), although the latter preparations had a higher specific activity. The microsomal activity was exclusively NADPH dependent. A minor part of the cytosolic reduction was determined by nonenzymatic components, notably by some electron donors and chiefly by reduced glutathione, which proved to reduce chromium(VI) at physiological concentrations. However, also in cytosolic fractions, the most important contribution to chromium reduction was enzyme catalyzed, as shown by the following properties: thermolability; requirement for exogenous NADH or NADPH [supplied as such or in the form of a NADPH-generating system (S-9 mix)]; and saturation by chromium(VI). The likely involvement of DT-diaphorase in this metabolic process is supported by several findings, including its sharp pH dependence and its partial suppression by known inhibitors of this enzyme protein, such as p-chloromercuribenzoate, L-thyroxine, and dicumarol (which conversely did not counteract the metabolic deactivation of the other direct-acting mutagens 2-methoxy-6-chloro-9-[3-(2-chloroethyl)aminopropylamino]acridine 2HCl and epichlorohydrin). Similarly, cytosolic reduction of chromium(VI) was partially inhibited by selective metabolic depletors of both coenzymes of DT-diaphorase, i.e., NADPH and NADH. Pretreatment of rats with enzyme inducers (phenobarbital and 3-methylcholanthrene) stimulated the activity of DT-diaphorase in liver cytosolic fractions. A dramatic stimulation (35 to 40 times over untreated controls) was produced by Aroclor 1254, which also coinduced the liver cytosolic activity of enzymes involved in the glucose 6-phosphate-dependent pathway of both nicotinamideadenine-dinucleotide phosphate and glutathione reduction (glucose-6-phosphate dehydrogenase, 6-phosphogluconate dehydrogenase, and glutathione reductase). In the lung cytosol, a slight yet significant stimulation of some of these enzyme activities was determined by the daily intratracheal instillations of high doses of chromium(VI) itself for 4 weeks, a condition which has been found to enhance the pulmonary metabolism of this metal ion."
14092,Korallus 1986,"Chromium compounds: Occupational health, toxicological and biological monitoring aspects","For the biological evaluation of Cr and Cr?compounds the valency state is of essential importance: Cr?metal and Cr(III)?compounds are neither irritant nor allergenic nor mutagenic nor carcinogenic, according to unanimous toxicological and epidemiological understanding. Daily minimum uptake as an essential trace element is necessary. Cr(VI)?compounds are irritating resp. corrosive for skin and mucous membranes, mutagenic in short term tests (Ames). The poorly water soluble Cr(VI)salts of Ca, Cr(III), Sr and Zn are carcinogenic whereas CrO3 and Alkali chromates and Dichromates are not carcinogenic, in accordance with toxicological and epidemiological observations. The increased mortality of lung cancer, observed in earlier decades among employees of the chromate producing industry, was decreased to nearly the expected values in the general population, due to changes of the processing and improved industrial hygiene. Up to 2ppm Cr(VI) is reduced to Cr(III) in human plasma spontaneous by formation of Cr?protein complexes. In the case of an intoxication this is promoted by ascorbic acid which also enhances and accelerates renal excretion. Higher concentrations lead to the permeation of the erythrocyte membranes and fixation with proteins inside the cell. This leads to new principles of Biological Monitoring: As Cr(VI) is stored inside the cells for their life span of about 120 d it can be detected there for this period. In contrast, Cr(III) is taken up by the cell to a markedly lower extent and can be removed by successive dialysing steps because it is not fixed to proteins. Classification and threshold values are demonstrated.","Chromium compounds: Occupational health, toxicological and biological monitoring aspects Abs: For the biological evaluation of Cr and Cr?compounds the valency state is of essential importance: Cr?metal and Cr(III)?compounds are neither irritant nor allergenic nor mutagenic nor carcinogenic, according to unanimous toxicological and epidemiological understanding. Daily minimum uptake as an essential trace element is necessary. Cr(VI)?compounds are irritating resp. corrosive for skin and mucous membranes, mutagenic in short term tests (Ames). The poorly water soluble Cr(VI)salts of Ca, Cr(III), Sr and Zn are carcinogenic whereas CrO3 and Alkali chromates and Dichromates are not carcinogenic, in accordance with toxicological and epidemiological observations. The increased mortality of lung cancer, observed in earlier decades among employees of the chromate producing industry, was decreased to nearly the expected values in the general population, due to changes of the processing and improved industrial hygiene. Up to 2ppm Cr(VI) is reduced to Cr(III) in human plasma spontaneous by formation of Cr?protein complexes. In the case of an intoxication this is promoted by ascorbic acid which also enhances and accelerates renal excretion. Higher concentrations lead to the permeation of the erythrocyte membranes and fixation with proteins inside the cell. This leads to new principles of Biological Monitoring: As Cr(VI) is stored inside the cells for their life span of about 120 d it can be detected there for this period. In contrast, Cr(III) is taken up by the cell to a markedly lower extent and can be removed by successive dialysing steps because it is not fixed to proteins. Classification and threshold values are demonstrated."
14089,Albert 1991,Issues in the risk assessment of chromium,"Although hexavalent chromium is well established as a human carcinogen by the inhalation route, there are significant uncertainties in the quantitative estimation of cancer risk. One of the important uncertainties is the assumption that the carcinogenic potency, determined under conditions of occupational exposure where most workers were cigarette smokers, applies to the nonsmoking individual in the general population. There is substantial evidence that carcinogenicity is a function of the rate of cell turnover in the target tissue. The chromate worker would be expected to have a relatively high rate of cell proliferation in the bronchial mucosa due to airborne irritants and smoking. The potency of chromium might therefore be relatively high under conditions of occupational exposure. This problem in quantitative risk assessment applies equally well to another important indoor pollutant, radon.","Issues in the risk assessment of chromium Abs: Although hexavalent chromium is well established as a human carcinogen by the inhalation route, there are significant uncertainties in the quantitative estimation of cancer risk. One of the important uncertainties is the assumption that the carcinogenic potency, determined under conditions of occupational exposure where most workers were cigarette smokers, applies to the nonsmoking individual in the general population. There is substantial evidence that carcinogenicity is a function of the rate of cell turnover in the target tissue. The chromate worker would be expected to have a relatively high rate of cell proliferation in the bronchial mucosa due to airborne irritants and smoking. The potency of chromium might therefore be relatively high under conditions of occupational exposure. This problem in quantitative risk assessment applies equally well to another important indoor pollutant, radon."
14082,Roe and  Carter 1969,Chromium carcinogenesis: calcium chromate as a potent carcinogen for the subcutaneous tissues of the rat,,Chromium carcinogenesis: calcium chromate as a potent carcinogen for the subcutaneous tissues of the rat Abs: 
14081,Wild 1978,Cytogenetic effects in the mouse of 17 chemical mutagens and carcinogens evaluated by the micronucleus test,"2 dialkylnitrosamines, 4 oxazaphosphorines, 6 aryldialkyltriazenes, urethane, N-hydroxyurethane, 4-nitroquinoline-1-oxide, procarbazine (natulan) and the inorganic carcinogen potassium chromate were studied for cytogenetic activity in the micronucleus test on mouse bone marrow. Except diethylnitrosamine, all chemicals were active. The results are compared with those known from studies in other mammalian and sub-mammalian test systems. The results of the micro nucleus test correlate well with results from other mutagenicity tests and with the carcinogenicity of the chemicals. The lack of an effect on N-nitrosodiethylamine (DENA) is discussed with regard to the short life-time of the ultimate mutagen.","Cytogenetic effects in the mouse of 17 chemical mutagens and carcinogens evaluated by the micronucleus test Abs: 2 dialkylnitrosamines, 4 oxazaphosphorines, 6 aryldialkyltriazenes, urethane, N-hydroxyurethane, 4-nitroquinoline-1-oxide, procarbazine (natulan) and the inorganic carcinogen potassium chromate were studied for cytogenetic activity in the micronucleus test on mouse bone marrow. Except diethylnitrosamine, all chemicals were active. The results are compared with those known from studies in other mammalian and sub-mammalian test systems. The results of the micro nucleus test correlate well with results from other mutagenicity tests and with the carcinogenicity of the chemicals. The lack of an effect on N-nitrosodiethylamine (DENA) is discussed with regard to the short life-time of the ultimate mutagen."
14066,Suzuki and  Fukuda 1990,Reduction of hexavalent chromium by ascorbic acid and glutathione with special reference to the rat lung,"The reduction of 20 ?M hexavalent chromium [chromium(VI)] byl-ascorbic acid (AsA) (0.06–2 mM) and/or glutathione (GSH) (2–15 mM) in buffer solutions, cell-free bronchoalveolar lavage fluids or soluble fractions of rat lungs was investigated at physiological pH (37° C). The reduction in AsA solution was pseudo-first-order in a single phase with respect to chromium(VI), but that in GSH solution showed a two-phase process. The half-life of chromium(IV) ranged from seconds to hours. The reducing ability of AsA was markedly higher than that of GSH. Coexistence of equimolar GSH with AsA accelerated the reduction rate slightly, in comparison with that in the corresponding AsA solution. Lavage fluids containing 0.06 mM AsA showed pH-dependent reactions similar to those of the corresponding AsA solutions. The lungsoluble fractions reduced chromium(VI) in a process composed of phase I and phase II, characterized by the reducing ability of AsA-GSH cooperation and of AsA alone, respectively. Reduction in the former was 30–40% more rapid than in the latter. The biological half-life of chromium(VI) in the lung was estimated to be 0.6 min, on the basis of the reducing activity in the first phase. However, the apparent biological half-life of chromium(VI) was about 2 min in rat lungs after intratracheal injection of chromate, involving depletion of AsA, but no significant changes in GSH. The difference is discussed in terms of AsA-induced initiative reduction in the alveolar lining fluid and subsequent obstructive effects of the resulting trivalent species on trans-membrane permeability of chromate anions. These results suggest that AsA is more reactive than GSH in the reduction of chromium(VI) in the rat lung and that the extracellular AsA in the alveolar lining fluid plays an important role in antioxidant defense against inhaled chromium(VI) compounds.","Reduction of hexavalent chromium by ascorbic acid and glutathione with special reference to the rat lung Abs: The reduction of 20 ?M hexavalent chromium [chromium(VI)] byl-ascorbic acid (AsA) (0.06–2 mM) and/or glutathione (GSH) (2–15 mM) in buffer solutions, cell-free bronchoalveolar lavage fluids or soluble fractions of rat lungs was investigated at physiological pH (37° C). The reduction in AsA solution was pseudo-first-order in a single phase with respect to chromium(VI), but that in GSH solution showed a two-phase process. The half-life of chromium(IV) ranged from seconds to hours. The reducing ability of AsA was markedly higher than that of GSH. Coexistence of equimolar GSH with AsA accelerated the reduction rate slightly, in comparison with that in the corresponding AsA solution. Lavage fluids containing 0.06 mM AsA showed pH-dependent reactions similar to those of the corresponding AsA solutions. The lungsoluble fractions reduced chromium(VI) in a process composed of phase I and phase II, characterized by the reducing ability of AsA-GSH cooperation and of AsA alone, respectively. Reduction in the former was 30–40% more rapid than in the latter. The biological half-life of chromium(VI) in the lung was estimated to be 0.6 min, on the basis of the reducing activity in the first phase. However, the apparent biological half-life of chromium(VI) was about 2 min in rat lungs after intratracheal injection of chromate, involving depletion of AsA, but no significant changes in GSH. The difference is discussed in terms of AsA-induced initiative reduction in the alveolar lining fluid and subsequent obstructive effects of the resulting trivalent species on trans-membrane permeability of chromate anions. These results suggest that AsA is more reactive than GSH in the reduction of chromium(VI) in the rat lung and that the extracellular AsA in the alveolar lining fluid plays an important role in antioxidant defense against inhaled chromium(VI) compounds."
14065,Kalliomäki et al. 1982,Retention of stainless steel manual metal arc welding fumes in rats,"Twenty male Wistar rats were exposed to MMA/SS welding fumes. The exposure situation of the study simulated the features of the actual environment as closely as possible. The lung retention of the elements of interest present in MMA/SS welding fumes as well as their distribution in other organs of the rats were investigated. The rats were intermittently exposed to MMA/SS welding fumes maximally for 10 h, the fume concentration being 43 mg/m 3 . Atomic absorption spectrometry was used for the analyses of Cr and Ni concentrations in the blood, whereas instrumental neutron activation analysis was applied in the multielement analysis of organ samples of the rats. Exogenous lung iron was determined by means of the magnetic measuring technique. The concentrations of Cr, Ni, and exogenous Fe in the lungs and Cr in the blood, kidneys, and spleen increased linearly with increasing exposure time. The retention rates of these elements in the organs examined are also given. According to the lung retention and distribution model of Cr, the lungs constituted the target organ to the soluble, hexavalent chromates present in the MMA/SS welding fumes, although the Cr present in MMA/SS welding fumes has been proven to be in a water?soluble hexavalent form up to 95%, approximately 30% of the total inhaled Cr was soluble in the tissue. The distribution pattern of Cr in the organs differs from those obtained after single intravenous or intratracheal injections of alkaline chromates. The results show that the magnetic measuring method can be used to measure the retention of welding fumes by the lungs.","Retention of stainless steel manual metal arc welding fumes in rats Abs: Twenty male Wistar rats were exposed to MMA/SS welding fumes. The exposure situation of the study simulated the features of the actual environment as closely as possible. The lung retention of the elements of interest present in MMA/SS welding fumes as well as their distribution in other organs of the rats were investigated. The rats were intermittently exposed to MMA/SS welding fumes maximally for 10 h, the fume concentration being 43 mg/m 3 . Atomic absorption spectrometry was used for the analyses of Cr and Ni concentrations in the blood, whereas instrumental neutron activation analysis was applied in the multielement analysis of organ samples of the rats. Exogenous lung iron was determined by means of the magnetic measuring technique. The concentrations of Cr, Ni, and exogenous Fe in the lungs and Cr in the blood, kidneys, and spleen increased linearly with increasing exposure time. The retention rates of these elements in the organs examined are also given. According to the lung retention and distribution model of Cr, the lungs constituted the target organ to the soluble, hexavalent chromates present in the MMA/SS welding fumes, although the Cr present in MMA/SS welding fumes has been proven to be in a water?soluble hexavalent form up to 95%, approximately 30% of the total inhaled Cr was soluble in the tissue. The distribution pattern of Cr in the organs differs from those obtained after single intravenous or intratracheal injections of alkaline chromates. The results show that the magnetic measuring method can be used to measure the retention of welding fumes by the lungs."
14062,Tsuda and  Kato 1977,Chromosomal aberrations and morphological transformation in hamster embryonic cells treated with potassium dichromate in vitro,"The addition of K2Cr2O7, at concentrations ranging from 0.1 to 0.5 microng/ml, to hamster total embryonic cells for 24 h, resulted in consistent and drastic chromosomal aberrations including gaps, breaks and exchanges. The above effect, however, was reduced successfully by the addition of a reducing agent, Na2SO3. Among other chromium compounds examined, divalent and trivalent chromium salts were ineffective on chromosome morphology even at a concentration of 3.5 microng/ml as chromium, whereas a hexavalent compound, CrO3, was highly effective. K2Cr2O7 also enhanced the morphological transformation rate in a short-term colony assay, in whicy hamster embryonic cells (1x10(4) cells/60-mm dish) were treated and the morphology was observed 8 to 10 days after the treatment.","Chromosomal aberrations and morphological transformation in hamster embryonic cells treated with potassium dichromate in vitro Abs: The addition of K2Cr2O7, at concentrations ranging from 0.1 to 0.5 microng/ml, to hamster total embryonic cells for 24 h, resulted in consistent and drastic chromosomal aberrations including gaps, breaks and exchanges. The above effect, however, was reduced successfully by the addition of a reducing agent, Na2SO3. Among other chromium compounds examined, divalent and trivalent chromium salts were ineffective on chromosome morphology even at a concentration of 3.5 microng/ml as chromium, whereas a hexavalent compound, CrO3, was highly effective. K2Cr2O7 also enhanced the morphological transformation rate in a short-term colony assay, in whicy hamster embryonic cells (1x10(4) cells/60-mm dish) were treated and the morphology was observed 8 to 10 days after the treatment."
14058,Rahkonen et al. 1983,Evaluation of biological monitoring among stainless steel welders,"HEEP COPYRIGHT: BIOL ABS. Ten manual metal arc (MMA) high alloy stainless steel (SS) welders were studied during 1 wk and the concentrations of Cr and Ni were determined in their urine and blood. Stationary and personal air samples were collected from the immediate work environment; they covered the entire work period. Spot urine samples were collected during the follow-up period. Whole blood and plasma samples were taken from the workers before and after 1 shift, and the retention rate of magnetic dust in the lungs was estimated with magnetopneumography. Indices of short-term exposure to Cr and Ni were evaluated. Urinary Cr and Ni concentrations (corrected to creatinine) reflected the body burden caused by long-term and short-term exposure to easily soluble fractions of these metals. The use of Cr and Ni urinary analyses as indices of short-term exposure was not as dependable as previously assumed. The Cr and Ni concentrations in whole blood and plasma did not correlate with the measured exposure, but the daily mean increase in the Cr concentration reflected exposure to total Cr and Cr(VI) very well. The large variation in the Cr concentration of the morning urine (0.01-2.7 mumol/l) and blood (0.05-1.43 mumol/l) indicated large personal variations of body burden among the exposed welders. The retention rate of magnetic dust in the lungs correlated well (P 0.01) with the daily mean increase of Cr in blood. Good correlations (P 0.001) were found between the retention rate of magnetic dust and the personal air samples of Cr and Cr(VI).","Evaluation of biological monitoring among stainless steel welders Abs: HEEP COPYRIGHT: BIOL ABS. Ten manual metal arc (MMA) high alloy stainless steel (SS) welders were studied during 1 wk and the concentrations of Cr and Ni were determined in their urine and blood. Stationary and personal air samples were collected from the immediate work environment; they covered the entire work period. Spot urine samples were collected during the follow-up period. Whole blood and plasma samples were taken from the workers before and after 1 shift, and the retention rate of magnetic dust in the lungs was estimated with magnetopneumography. Indices of short-term exposure to Cr and Ni were evaluated. Urinary Cr and Ni concentrations (corrected to creatinine) reflected the body burden caused by long-term and short-term exposure to easily soluble fractions of these metals. The use of Cr and Ni urinary analyses as indices of short-term exposure was not as dependable as previously assumed. The Cr and Ni concentrations in whole blood and plasma did not correlate with the measured exposure, but the daily mean increase in the Cr concentration reflected exposure to total Cr and Cr(VI) very well. The large variation in the Cr concentration of the morning urine (0.01-2.7 mumol/l) and blood (0.05-1.43 mumol/l) indicated large personal variations of body burden among the exposed welders. The retention rate of magnetic dust in the lungs correlated well (P 0.01) with the daily mean increase of Cr in blood. Good correlations (P 0.001) were found between the retention rate of magnetic dust and the personal air samples of Cr and Cr(VI)."
14056,Langard and  Vigander 1983,Occurrence of lung cancer in workers producing chromium pigments,"The results of a follow-up study on the incidence of lung cancer in 133 workers producing zinc chromate pigments are presented. By the end of 1972 three cases of lung cancer had occurred in a sub-cohort of 24 workers who had been employed for over three years. The same group of workers has now been followed up to December 1980 and three further cases of lung cancer were found. The observed/expected ratio was 44 in this group, virtually the same as at the end of 1972. Five of the six patients smoked. Only one had been exposed to chromates other than zinc chromates.","Occurrence of lung cancer in workers producing chromium pigments Abs: The results of a follow-up study on the incidence of lung cancer in 133 workers producing zinc chromate pigments are presented. By the end of 1972 three cases of lung cancer had occurred in a sub-cohort of 24 workers who had been employed for over three years. The same group of workers has now been followed up to December 1980 and three further cases of lung cancer were found. The observed/expected ratio was 44 in this group, virtually the same as at the end of 1972. Five of the six patients smoked. Only one had been exposed to chromates other than zinc chromates."
14055,Jones 1990,Hexavalent chrome: threshold concept for carcinogenicity,"Certain hexavalent chromium (Cr6+) compounds when administered via inhalation at high doses have the potential to induce lung tumors in humans and experimental animals. Trivalent chromium (Cr3+) is an essential human and animal nutrient at levels of 50 to 200 micrograms/day. Recent data have shown that the human body is able to reduce Cr6+ to Cr3+. This reduction occurs in bodily fluids such as gastric juice, epithelial lining fluid of the respiratory tract, blood, and other fluids. Secondary reduction occurs at the cellular level by the cytosol, mitochondria, and microsomes. Thus, at low levels of exposure hexavalent chromium ions are reduced before the 6+ ions can interact with DNA unless the dose is sufficient to overwhelm the body's reduction capacity. This paper summarizes the available data concerning the reducing ability of the body and formulates the steps in the mechanism of cancer induction. These steps include: (1) only certain Cr6+ compounds have the capacity to interact with cellular components; (2) Cr6+ is reduced by body fluids and excess Cr6+ enters the cell (Cr3+ is poorly absorbed across membranes); (3) cellular organelles and the cytoplasm reduce Cr6+ to Cr3+; (4) excess Cr6+ can enter the nucleus; (5) Cr6+ reduction through 5+ and 4+ to 3+ has a potential to interact with the DNA molecule; and (6) if unrepaired, this DNA damage can lead to cancer induction. On the basis of current evidence Cr6+ has a threshold for carcinogenic potential in humans that is greater than the current TLV.","Hexavalent chrome: threshold concept for carcinogenicity Abs: Certain hexavalent chromium (Cr6+) compounds when administered via inhalation at high doses have the potential to induce lung tumors in humans and experimental animals. Trivalent chromium (Cr3+) is an essential human and animal nutrient at levels of 50 to 200 micrograms/day. Recent data have shown that the human body is able to reduce Cr6+ to Cr3+. This reduction occurs in bodily fluids such as gastric juice, epithelial lining fluid of the respiratory tract, blood, and other fluids. Secondary reduction occurs at the cellular level by the cytosol, mitochondria, and microsomes. Thus, at low levels of exposure hexavalent chromium ions are reduced before the 6+ ions can interact with DNA unless the dose is sufficient to overwhelm the body's reduction capacity. This paper summarizes the available data concerning the reducing ability of the body and formulates the steps in the mechanism of cancer induction. These steps include: (1) only certain Cr6+ compounds have the capacity to interact with cellular components; (2) Cr6+ is reduced by body fluids and excess Cr6+ enters the cell (Cr3+ is poorly absorbed across membranes); (3) cellular organelles and the cytoplasm reduce Cr6+ to Cr3+; (4) excess Cr6+ can enter the nucleus; (5) Cr6+ reduction through 5+ and 4+ to 3+ has a potential to interact with the DNA molecule; and (6) if unrepaired, this DNA damage can lead to cancer induction. On the basis of current evidence Cr6+ has a threshold for carcinogenic potential in humans that is greater than the current TLV."
14053,Norseth et al. 1982,Biliary excretion of chromium in the rat: a role of glutathione,"The relative amount of chromium excreted in rat bile after injection of Cr-III is much less than after injection of Cr-VI, about 0.1% and from 6-8% during 5 hours respectively, for corresponding dose levels. The liver to bile ratio was 50-100 for Cr-III injection, for Cr-VI the ratio was 2-3. With doses up to 18 mumol Cr/kg, only Cr-III was found in bile even after injection of Cr-VI. Glutathione depletion of the liver with cyclohexene oxide decreased chromium excretion in bile. Such treatment also decreased the reduction of Cr-VI to Cr-III in the liver cell as only Cr-VI was found in bile. A different distribution of Cr-III in the liver dependent on whether derived from Cr-VI or taken up by the liver as such must be assumed. Taking into account the usual low penetration of biological membranes by Cr-III, a possible active transport mechanism or a specific diffusable Cr-III compound must be postulated.","Biliary excretion of chromium in the rat: a role of glutathione Abs: The relative amount of chromium excreted in rat bile after injection of Cr-III is much less than after injection of Cr-VI, about 0.1% and from 6-8% during 5 hours respectively, for corresponding dose levels. The liver to bile ratio was 50-100 for Cr-III injection, for Cr-VI the ratio was 2-3. With doses up to 18 mumol Cr/kg, only Cr-III was found in bile even after injection of Cr-VI. Glutathione depletion of the liver with cyclohexene oxide decreased chromium excretion in bile. Such treatment also decreased the reduction of Cr-VI to Cr-III in the liver cell as only Cr-VI was found in bile. A different distribution of Cr-III in the liver dependent on whether derived from Cr-VI or taken up by the liver as such must be assumed. Taking into account the usual low penetration of biological membranes by Cr-III, a possible active transport mechanism or a specific diffusable Cr-III compound must be postulated."
14046,Mutti et al. 1984,Biological monitoring of occupational exposure to different chromium compounds at various valency states,,Biological monitoring of occupational exposure to different chromium compounds at various valency states Abs: 
14042,Manzo et al. 1983,Biliary and gastrointestinal excretion of chromium after administration of Cr-III and Cr-VI in rats,"Rats treated intravenously with 51Cr-labelled sodium chromate, 0.1 or 100 microgram Cr/rat, excreted more 51Cr into bile in a 2-hr period than did the animals given equal amounts of chromium in the trivalent state. Distinct patterns of hepatic intracellular distribution of the radiotracer were also observed. In the Cr-VI rats over 50% of the liver chromium was present in the supernatant fraction whereas in the Cr-III rats almost all the liver radioactivity was localized in the cell organelles. Fractionation of bile on Sephadex G-75 demonstrated binding of chromium to low-molecular weight substances. It is suggested that complexes of chromium with low-molecular weight components of liver cytosol are involved in the passage of this element from the liver to bile. A low cytosolic content of diffusable Cr-complexes associated with the incorporation of a large fraction of liver chromium in cell organelles may be a factor contributing to the low rates of 51Cr biliary excretion in the animals given Cr-III. 24 hr after the injection of 51Cr to bile duct-ligated rats appreciable levels of radiotracer were found in the gastrointestinal tract. The animals given Cr-VI exhibited significantly higher values of chromium content in the gut than those treated with Cr-III.","Biliary and gastrointestinal excretion of chromium after administration of Cr-III and Cr-VI in rats Abs: Rats treated intravenously with 51Cr-labelled sodium chromate, 0.1 or 100 microgram Cr/rat, excreted more 51Cr into bile in a 2-hr period than did the animals given equal amounts of chromium in the trivalent state. Distinct patterns of hepatic intracellular distribution of the radiotracer were also observed. In the Cr-VI rats over 50% of the liver chromium was present in the supernatant fraction whereas in the Cr-III rats almost all the liver radioactivity was localized in the cell organelles. Fractionation of bile on Sephadex G-75 demonstrated binding of chromium to low-molecular weight substances. It is suggested that complexes of chromium with low-molecular weight components of liver cytosol are involved in the passage of this element from the liver to bile. A low cytosolic content of diffusable Cr-complexes associated with the incorporation of a large fraction of liver chromium in cell organelles may be a factor contributing to the low rates of 51Cr biliary excretion in the animals given Cr-III. 24 hr after the injection of 51Cr to bile duct-ligated rats appreciable levels of radiotracer were found in the gastrointestinal tract. The animals given Cr-VI exhibited significantly higher values of chromium content in the gut than those treated with Cr-III."
14039,Lindberg and  Vesterberg 1983,Monitoring exposure to chromic acid in chromeplating by measuring chromium in urine,"With personal air samplers, exposure to hexavalent chromium was measured in a group of eight chromeplaters during a period of 5 d; urine samples were collected at all times of urination for 7 d. The concentration of chromium in the urine increased from Monday morning to Tuesday afternoon and then remained constant within the group as a whole throughout the rest of the work week. In a large group of 90 chromeplaters exposure was measured for 1 d, and urine samples were collected before and after the workshift on Monday and Thursday of the same week. There was a correlation between the exposure and the concentration of chromium in postshift urine samples on Thursday (correlation coefficient 0.71). Concentrations of chromium in urine of less than or equal to 100 nmol/l indicate time-weighted average values of exposure of about or below 2 micrograms/m3. Below this exposure no severe damage to the nasal septum and no influence on lung function have been found. After the initial measuring of the airborne hexavalent chromium and the concentrations of chromium in the urine of exposed workers, urine analyses are recommended for follow-up controls.","Monitoring exposure to chromic acid in chromeplating by measuring chromium in urine Abs: With personal air samplers, exposure to hexavalent chromium was measured in a group of eight chromeplaters during a period of 5 d; urine samples were collected at all times of urination for 7 d. The concentration of chromium in the urine increased from Monday morning to Tuesday afternoon and then remained constant within the group as a whole throughout the rest of the work week. In a large group of 90 chromeplaters exposure was measured for 1 d, and urine samples were collected before and after the workshift on Monday and Thursday of the same week. There was a correlation between the exposure and the concentration of chromium in postshift urine samples on Thursday (correlation coefficient 0.71). Concentrations of chromium in urine of less than or equal to 100 nmol/l indicate time-weighted average values of exposure of about or below 2 micrograms/m3. Below this exposure no severe damage to the nasal septum and no influence on lung function have been found. After the initial measuring of the airborne hexavalent chromium and the concentrations of chromium in the urine of exposed workers, urine analyses are recommended for follow-up controls."
14036,Lewalter et al. 1985,Chromium bond detection in isolated erythrocytes: a new principle of biological monitoring of exposure to hexavalent chromium,"Internal stress to chromium is only relevant in occupational medicine if it is due to the handling of hexavalent chromium. Cr(VI) ions, after uptake by inhalation or percutaneously are carried in the blood plasma and penetrate--depending on the concentration--into the erythrocytes. Due to the intracellular reduction to Cr(III) and the concurrent intracellular protein binding, the erythrocytes represent an easily accessible target organ for quantitative chromium determination after occupational exposure to Cr(VI) compounds. The results of an earlier experimental study indicate that human plasma too is capable of spontaneous reduction of Cr(VI) ions of up to 2 ppm to Cr(III). This plasma reduction capacity (PRC) can be increased and accelerated considerably by adding ascorbic acid (AA). These findings were supported in this investigation by proving a decreased binding of Cr(VI) inside the erythrocytes under the effect of AA. This leads to the assumption that only those Cr(VI) concentrations can penetrate the membrane of the erythrocytes and enter the cell which either come into contact with the membrane during the reduction process or exceed this limit concentration of 2 ppm. Only in these two instances can corresponding chromium findings be analyzed in isolated and washed erythrocytes. These results are compared with those obtained by conventional methods, such as Cr determination in the blood and/or urine. Our findings indicate that a single determination of chromium concentration in the erythrocytes will permit the monitoring of critical cases of Cr(VI) exposure. This is a new type of biological monitoring in the sense of a condensed longitudinal study, in order to find out whether threshold concentrations have been respected over a given period.","Chromium bond detection in isolated erythrocytes: a new principle of biological monitoring of exposure to hexavalent chromium Abs: Internal stress to chromium is only relevant in occupational medicine if it is due to the handling of hexavalent chromium. Cr(VI) ions, after uptake by inhalation or percutaneously are carried in the blood plasma and penetrate--depending on the concentration--into the erythrocytes. Due to the intracellular reduction to Cr(III) and the concurrent intracellular protein binding, the erythrocytes represent an easily accessible target organ for quantitative chromium determination after occupational exposure to Cr(VI) compounds. The results of an earlier experimental study indicate that human plasma too is capable of spontaneous reduction of Cr(VI) ions of up to 2 ppm to Cr(III). This plasma reduction capacity (PRC) can be increased and accelerated considerably by adding ascorbic acid (AA). These findings were supported in this investigation by proving a decreased binding of Cr(VI) inside the erythrocytes under the effect of AA. This leads to the assumption that only those Cr(VI) concentrations can penetrate the membrane of the erythrocytes and enter the cell which either come into contact with the membrane during the reduction process or exceed this limit concentration of 2 ppm. Only in these two instances can corresponding chromium findings be analyzed in isolated and washed erythrocytes. These results are compared with those obtained by conventional methods, such as Cr determination in the blood and/or urine. Our findings indicate that a single determination of chromium concentration in the erythrocytes will permit the monitoring of critical cases of Cr(VI) exposure. This is a new type of biological monitoring in the sense of a condensed longitudinal study, in order to find out whether threshold concentrations have been respected over a given period."
14033,Korallus et al. 1984,Experimental bases for ascorbic acid therapy of poisoning by hexavalent chromium compounds,"The most frequent outcome of the usually transdermal absorption of hexavalent chromium compounds is uraemia due to tubular necrosis. We have confirmed earlier observations that this can be prevented by the immediate application of ascorbic acid (AA) with the aim of reducing Cr(VI) to Cr(III). The spontaneous reducing capacity of samples of serum and plasma for Cr(VI) compounds was polarographically determined to be about 2 ppm. Addition of AA in doses of 50 to 1000 ppm led to a rapid and dose-dependent reduction of chromium(VI), which was studied on the concentration level of 5 ppm. For example in the presence of 1000 ppm AA, five ppm chromium(VI) fade to 0.7 ppm within 20 min and to undetectable concentrations after 40 min. These experiments demonstrate the effectiveness of AA for the treatment of Cr(VI) poisoning. Reduction is increased and accelerated by AA and the resulting Cr(III)-protein complexes are non-toxic and can be excreted with the urine. Early and repeated high i.v. doses of AA are recommended as the therapy of choice for Cr(VI) poisoning. In cases of delayed medical treatment, AA should be immediately applied orally.","Experimental bases for ascorbic acid therapy of poisoning by hexavalent chromium compounds Abs: The most frequent outcome of the usually transdermal absorption of hexavalent chromium compounds is uraemia due to tubular necrosis. We have confirmed earlier observations that this can be prevented by the immediate application of ascorbic acid (AA) with the aim of reducing Cr(VI) to Cr(III). The spontaneous reducing capacity of samples of serum and plasma for Cr(VI) compounds was polarographically determined to be about 2 ppm. Addition of AA in doses of 50 to 1000 ppm led to a rapid and dose-dependent reduction of chromium(VI), which was studied on the concentration level of 5 ppm. For example in the presence of 1000 ppm AA, five ppm chromium(VI) fade to 0.7 ppm within 20 min and to undetectable concentrations after 40 min. These experiments demonstrate the effectiveness of AA for the treatment of Cr(VI) poisoning. Reduction is increased and accelerated by AA and the resulting Cr(III)-protein complexes are non-toxic and can be excreted with the urine. Early and repeated high i.v. doses of AA are recommended as the therapy of choice for Cr(VI) poisoning. In cases of delayed medical treatment, AA should be immediately applied orally."
14031,Kleinfeld and  Rosso 1965,Ulcerations of the nasal septum due to inhalation of chromic acid mist,,Ulcerations of the nasal septum due to inhalation of chromic acid mist Abs: 
14029,Kiilunen et al. 1983,Exceptional pharmacokinetics of trivalent chromium during occupational exposure to chromium lignosulfonate dust,"The excretion of chromium in the urine of workers exposed to chromium lignosulfonate was studied. The chromium in the dust was in the trivalent (III) oxidation state, and 30% of the particles were less than 5 micron in diameter. Chromium (III) lignosulfonate dust was rapidly absorbed, and a peak of urinary excretion was seen immediately after exposure. No appreciable accumulation of chromium occurred over 3 d, as evaluated by comparison with preshift urinary chromium concentrations. The addition of ethylenediaminetetra-acetate to the urine of exposed persons greatly enhanced the capacity of chromium to traverse a dialysis membrane; the same effect was seen with chromium (III) chloride. It is concluded that chromium (III) lignosulfonate yields chromium (III), which acts pharmacokinetically like water-soluble hexavalent chromium compounds.","Exceptional pharmacokinetics of trivalent chromium during occupational exposure to chromium lignosulfonate dust Abs: The excretion of chromium in the urine of workers exposed to chromium lignosulfonate was studied. The chromium in the dust was in the trivalent (III) oxidation state, and 30% of the particles were less than 5 micron in diameter. Chromium (III) lignosulfonate dust was rapidly absorbed, and a peak of urinary excretion was seen immediately after exposure. No appreciable accumulation of chromium occurred over 3 d, as evaluated by comparison with preshift urinary chromium concentrations. The addition of ethylenediaminetetra-acetate to the urine of exposed persons greatly enhanced the capacity of chromium to traverse a dialysis membrane; the same effect was seen with chromium (III) chloride. It is concluded that chromium (III) lignosulfonate yields chromium (III), which acts pharmacokinetically like water-soluble hexavalent chromium compounds."
14012,Elias et al. 1983,Sister chromatid exchanges in Chinese hamster V79 cells treated with the trivalent chromium compounds chromic chloride and chromic oxide,"The induction of sister chromatid exchanges (SCEs) in Chinese hamster V79 cells exposed to soluble CrCl3 and insoluble Cr2O3, compounds of trivalent chromium (Cr3+), was determined. Their ability to induce SCEs was compared with those of three hexavalent chromium (Cr6+) compounds: K2CrO4, Na2CrO4 and Na2Cr2O7. Both the delay in progression through the cell cycle induced by Cr3+ compounds and the SCE frequencies in the delayed cells were also evaluated. The exposure for 28 h to CrCl3 and Cr2O3 at concentrations of 9.7-39 micrograms and of 34-136 micrograms of Cr3+ per ml, respectively, induced a statistically significant (p less than 0.001) dose-dependent increase in SCEs up to 1.9-fold (CrCl3) and 4-fold (Cr2O3) over control levels. Compared with the effective concentrations of Cr6+ compounds, which produced up to 4-fold increase of SCEs, inducing concentrations of CrCl3 and Cr2O3 were 300- and 1000-fold higher in terms of chromium. By prolongation of treatment time up to 48 h, a progressive dose- and time-related enhancement in SCE frequencies induced by Cr3+ compounds in delayed cells was observed. Lower concentrations of Cr2O3, without effect after 28 h of treatment, induced an increase of SCEs by prolongation of exposure time.","Sister chromatid exchanges in Chinese hamster V79 cells treated with the trivalent chromium compounds chromic chloride and chromic oxide Abs: The induction of sister chromatid exchanges (SCEs) in Chinese hamster V79 cells exposed to soluble CrCl3 and insoluble Cr2O3, compounds of trivalent chromium (Cr3+), was determined. Their ability to induce SCEs was compared with those of three hexavalent chromium (Cr6+) compounds: K2CrO4, Na2CrO4 and Na2Cr2O7. Both the delay in progression through the cell cycle induced by Cr3+ compounds and the SCE frequencies in the delayed cells were also evaluated. The exposure for 28 h to CrCl3 and Cr2O3 at concentrations of 9.7-39 micrograms and of 34-136 micrograms of Cr3+ per ml, respectively, induced a statistically significant (p less than 0.001) dose-dependent increase in SCEs up to 1.9-fold (CrCl3) and 4-fold (Cr2O3) over control levels. Compared with the effective concentrations of Cr6+ compounds, which produced up to 4-fold increase of SCEs, inducing concentrations of CrCl3 and Cr2O3 were 300- and 1000-fold higher in terms of chromium. By prolongation of treatment time up to 48 h, a progressive dose- and time-related enhancement in SCE frequencies induced by Cr3+ compounds in delayed cells was observed. Lower concentrations of Cr2O3, without effect after 28 h of treatment, induced an increase of SCEs by prolongation of exposure time."
14011,Venitt and  Levy 1974,Mutagenicity of chromates in bacteria and its relevance to chromate carcinogenesis,HEEP COPYRIGHT: BIOL ABS. NOTE RAT ESCHERICHIA-COLI CALCIUM CHROMATE CARCINOGEN LUNG TUMORS SARCOMA,Mutagenicity of chromates in bacteria and its relevance to chromate carcinogenesis Abs: HEEP COPYRIGHT: BIOL ABS. NOTE RAT ESCHERICHIA-COLI CALCIUM CHROMATE CARCINOGEN LUNG TUMORS SARCOMA
14008,Danielsson et al. 1982,Embryotoxicity of chromium: Distribution in pregnant mice and effects on embryonic cells in vitro,,Embryotoxicity of chromium: Distribution in pregnant mice and effects on embryonic cells in vitro Abs: 
14007,Cupo and  Wetterhahn 1985,Binding of chromium to chromatin and DNA from liver and kidney of rats treated with sodium dichromate and chromium(III) chloride in vivo,"The in vivo binding of chromium to whole chromatin, polynucleosomes, DNA, and cytoplasmic RNA-protein fraction from liver and kidney was examined after treatment of rats with sodium dichromate and chromium(III) chloride. Significant amounts of chromium were bound to DNA and the nonhistone proteins of chromatin and to cytoplasmic RNA-protein fraction. The binding of chromium to the nuclear and cytoplasmic nucleic acid fractions varied considerably, depending on the tissue and the oxidation state of the chromium administered. The level of chromium bound to whole chromatin was greater in the liver than in the kidney after treatment with either chromium compound. Chromium entered the liver and kidney tissues at a slower rate after chromium(III) treatment than after chromium(VI) treatment. At early times after chromium(VI) treatment, more chromium was bound to the liver and kidney chromatin and DNA than after chromium(III) treatment. A much smaller proportion of the chromium bound to chromatin was associated with the DNA after treatment with chromium(III) than after treatment with chromium(VI). However, 40 hr after injection, there was no significant difference in the level of chromium on the DNA from both the liver and kidney of chromium(VI)- and chromium(III)-treated animals. No DNA damage was detected in either liver or kidney nuclei after chromium(III) treatment, using the technique of alkaline elution. A possible correlation between chromium binding to chromatin and DNA damage is discussed.","Binding of chromium to chromatin and DNA from liver and kidney of rats treated with sodium dichromate and chromium(III) chloride in vivo Abs: The in vivo binding of chromium to whole chromatin, polynucleosomes, DNA, and cytoplasmic RNA-protein fraction from liver and kidney was examined after treatment of rats with sodium dichromate and chromium(III) chloride. Significant amounts of chromium were bound to DNA and the nonhistone proteins of chromatin and to cytoplasmic RNA-protein fraction. The binding of chromium to the nuclear and cytoplasmic nucleic acid fractions varied considerably, depending on the tissue and the oxidation state of the chromium administered. The level of chromium bound to whole chromatin was greater in the liver than in the kidney after treatment with either chromium compound. Chromium entered the liver and kidney tissues at a slower rate after chromium(III) treatment than after chromium(VI) treatment. At early times after chromium(VI) treatment, more chromium was bound to the liver and kidney chromatin and DNA than after chromium(III) treatment. A much smaller proportion of the chromium bound to chromatin was associated with the DNA after treatment with chromium(III) than after treatment with chromium(VI). However, 40 hr after injection, there was no significant difference in the level of chromium on the DNA from both the liver and kidney of chromium(VI)- and chromium(III)-treated animals. No DNA damage was detected in either liver or kidney nuclei after chromium(III) treatment, using the technique of alkaline elution. A possible correlation between chromium binding to chromatin and DNA damage is discussed."
14002,Cohen and  Kramkowski 1973,"Health hazard evaluation/toxicity determination. Marsh Plating Corporation, Ypsilanti, Michigan","Exposure to chromic-acid (7738945) as found in the nickel-chrome plating department of a plating corporation is found to be excessive. Symptoms include chronic rhinorrhea, sneezing, nasal sores, blood in the nasal mucous, frequent nosebleeds, and skin eruptions. Long term exposure to low levels of hexavalent chromium (7440473) in the work room atmosphere, direct contact of affected nasal tissues with hexavalent chromium, or a combination of both is considered the causative factor. Safety recommendations include strict warning about the safe usage of chromic acid, development of a safety program, proper use of protective gear, maintenance of general and personal hygiene, and refraining from eating, drinking and smoking in work areas.","Health hazard evaluation/toxicity determination. Marsh Plating Corporation, Ypsilanti, Michigan Abs: Exposure to chromic-acid (7738945) as found in the nickel-chrome plating department of a plating corporation is found to be excessive. Symptoms include chronic rhinorrhea, sneezing, nasal sores, blood in the nasal mucous, frequent nosebleeds, and skin eruptions. Long term exposure to low levels of hexavalent chromium (7440473) in the work room atmosphere, direct contact of affected nasal tissues with hexavalent chromium, or a combination of both is considered the causative factor. Safety recommendations include strict warning about the safe usage of chromic acid, development of a safety program, proper use of protective gear, maintenance of general and personal hygiene, and refraining from eating, drinking and smoking in work areas."
14001,Foa et al. 1988,Effects derived from long-term low-level chromium exposure in ferro-alloy metallurgy Study of absorption and renal function in workers,"Ferro-chromium production is based on the use of chromium oxide (III) and it is generally accepted that chromium in this form is not able to cross biological barriers. However, the data on the toxic and carcinogenic effects of hexavalent chromium in man are now firmly established. Some studies have questioned these data, calling for a clarification as to whether exposure to trivalent chromium can also produce human effects, perhaps with different latency time. A study was carried out on the exposure conditions (type and degree) in a ferro-chromium foundry that had been in operation since 1972. The absorption levels in the working population of the foundry, and the possible toxic effects on the kidney have been investigated. A total of 236 workers (142 employed in production departments, 33 office workers and 61 sub-contractor employees) were examined with measurement of the indicators of dose (urinary-chromium) and of effect on the kidney (albumin, retinol binding protein, and renal tubular epithelium antigens in the urine). Environmental hygiene measurements showed relatively low values of total chromium in the air (always less than 0.160 mg/m3). Hexavalent chromium was absent or, if present, at levels below the sensitivity of the analytical method used (0.001 mg/m3). The values of urinary chromium measured at the beginning and at the end of the working day and at the end of the work shift were always less than 5 micrograms/g creatinine, which has been proposed as a biological limit in chromium exposure. However, differences were observed between groups of subjects employed on different jobs, which is indicative of an absorption process varying according to the degree of exposure. The indicators of effect did not reveal any renal impairment, even early, that could be attributed to the toxic action of chromium.","Effects derived from long-term low-level chromium exposure in ferro-alloy metallurgy Study of absorption and renal function in workers Abs: Ferro-chromium production is based on the use of chromium oxide (III) and it is generally accepted that chromium in this form is not able to cross biological barriers. However, the data on the toxic and carcinogenic effects of hexavalent chromium in man are now firmly established. Some studies have questioned these data, calling for a clarification as to whether exposure to trivalent chromium can also produce human effects, perhaps with different latency time. A study was carried out on the exposure conditions (type and degree) in a ferro-chromium foundry that had been in operation since 1972. The absorption levels in the working population of the foundry, and the possible toxic effects on the kidney have been investigated. A total of 236 workers (142 employed in production departments, 33 office workers and 61 sub-contractor employees) were examined with measurement of the indicators of dose (urinary-chromium) and of effect on the kidney (albumin, retinol binding protein, and renal tubular epithelium antigens in the urine). Environmental hygiene measurements showed relatively low values of total chromium in the air (always less than 0.160 mg/m3). Hexavalent chromium was absent or, if present, at levels below the sensitivity of the analytical method used (0.001 mg/m3). The values of urinary chromium measured at the beginning and at the end of the working day and at the end of the work shift were always less than 5 micrograms/g creatinine, which has been proposed as a biological limit in chromium exposure. However, differences were observed between groups of subjects employed on different jobs, which is indicative of an absorption process varying according to the degree of exposure. The indicators of effect did not reveal any renal impairment, even early, that could be attributed to the toxic action of chromium."
13996,Bryson and  Goodall 1983,Differential toxicity and clearance kinetics of chromium(III) or (VI) in mice,"The acute and subacute toxicities of several chromium(III) and chromium(VI) compounds were determined in NZC and (CxO) mice injected i.p. The distal median lethal doses (more than 10 days after treatment) averaged (17.9 +/- 1.8) X 10(-6) g chromium/g body weight regardless of the oxidation state of the chromium compound injected (chromium(III) sulphate may be an exception), but acute toxicity (3 days) was much greater with chromium(VI) compounds. Acid digests of entire male mice that were administered i.p. one-sixth of the distal LD50, either once or repeatedly at weekly intervals, were analysed to determine the whole body persistence and clearance kinetics of chromium. Mice dosed once with chromium(III) retained 6.5 times more chromium at 21 days than mice treated with chromium(VI). When chromium(III) was given at weekly intervals mice accumulated 6 times more chromium by 8 weeks than chromium(VI)-treated mice, though only the latter showed symptoms of chronic toxicity. Whole body chromium concentrations continued to rise with further chromium(III) treatments, but slowly declined with chromium(VI). Analyses of fecal and urinary excretion confirmed most of the urinary chromium clearance occurred soon after injection, and that chromium excretion from chromium(VI)-treated animals was much faster in both urine and feces than from mice given chromium(III). The differential storage and clearance kinetics of chromium(III) and chromium(VI) compounds may be significant in experimental chromium carcinogenesis studies and in the toxicology of chromium in workers exposed industrially to potentially carcinogenic chromium-containing dusts or aerosols.","Differential toxicity and clearance kinetics of chromium(III) or (VI) in mice Abs: The acute and subacute toxicities of several chromium(III) and chromium(VI) compounds were determined in NZC and (CxO) mice injected i.p. The distal median lethal doses (more than 10 days after treatment) averaged (17.9 +/- 1.8) X 10(-6) g chromium/g body weight regardless of the oxidation state of the chromium compound injected (chromium(III) sulphate may be an exception), but acute toxicity (3 days) was much greater with chromium(VI) compounds. Acid digests of entire male mice that were administered i.p. one-sixth of the distal LD50, either once or repeatedly at weekly intervals, were analysed to determine the whole body persistence and clearance kinetics of chromium. Mice dosed once with chromium(III) retained 6.5 times more chromium at 21 days than mice treated with chromium(VI). When chromium(III) was given at weekly intervals mice accumulated 6 times more chromium by 8 weeks than chromium(VI)-treated mice, though only the latter showed symptoms of chronic toxicity. Whole body chromium concentrations continued to rise with further chromium(III) treatments, but slowly declined with chromium(VI). Analyses of fecal and urinary excretion confirmed most of the urinary chromium clearance occurred soon after injection, and that chromium excretion from chromium(VI)-treated animals was much faster in both urine and feces than from mice given chromium(III). The differential storage and clearance kinetics of chromium(III) and chromium(VI) compounds may be significant in experimental chromium carcinogenesis studies and in the toxicology of chromium in workers exposed industrially to potentially carcinogenic chromium-containing dusts or aerosols."
13994,Braver et al. 1985,An analysis of lung cancer risk from exposure to hexavalent chromium,"Lung cancer risk in relation to airborne levels of hexavalent chromium was analyzed for chromium chemical production workers studied by Hayes, Lilienfeld, and Snell. Hayes et al [18] had observed statistically significant increases in lung cancer mortality among chromium chemical production workers hired during 1945-1959 and followed to mid-1977. A dose-response was observed by Hayes et al. in that long-term workers had a higher lung cancer risk than short-term workers. Concurrent exposure data for the study plant were abstracted from the records of a local health department. The usual air concentration of hexavalent chromium was estimated as 413 micrograms per cubic meter (micrograms/m3) during 1945-1949. Cumulative exposure estimates for individual workers could not be developed with available information. Instead, cumulative exposures in terms of micrograms/m3-years were estimated for groups of short-term workers and long-term workers (cumulative exposure = usual exposure level in micrograms/m3 X average length of exposure). For workers hired during 1945-1949, cumulative exposures were estimated as 670 and 3,647 micrograms/m3-years for short-term and long-term workers, respectively. Like most estimates based on historical data, these exposure estimates are subject to uncertainty. Nevertheless, these results suggest a potential excess risk of death from lung cancer among U.S. workers exposed to the current permissible exposure limit (PEL) for hexavalent chromium of 52 micrograms/m3 because such workers could accumulate exposures (micrograms/m3-years) similar to those associated with excess risk in Hayes et al's cohort. Moreover, many current workers are estimated to be exposed to levels above the PEL. Further exploration of the dose-response relationship for chromium carcinogenesis is indicated.","An analysis of lung cancer risk from exposure to hexavalent chromium Abs: Lung cancer risk in relation to airborne levels of hexavalent chromium was analyzed for chromium chemical production workers studied by Hayes, Lilienfeld, and Snell. Hayes et al [18] had observed statistically significant increases in lung cancer mortality among chromium chemical production workers hired during 1945-1959 and followed to mid-1977. A dose-response was observed by Hayes et al. in that long-term workers had a higher lung cancer risk than short-term workers. Concurrent exposure data for the study plant were abstracted from the records of a local health department. The usual air concentration of hexavalent chromium was estimated as 413 micrograms per cubic meter (micrograms/m3) during 1945-1949. Cumulative exposure estimates for individual workers could not be developed with available information. Instead, cumulative exposures in terms of micrograms/m3-years were estimated for groups of short-term workers and long-term workers (cumulative exposure = usual exposure level in micrograms/m3 X average length of exposure). For workers hired during 1945-1949, cumulative exposures were estimated as 670 and 3,647 micrograms/m3-years for short-term and long-term workers, respectively. Like most estimates based on historical data, these exposure estimates are subject to uncertainty. Nevertheless, these results suggest a potential excess risk of death from lung cancer among U.S. workers exposed to the current permissible exposure limit (PEL) for hexavalent chromium of 52 micrograms/m3 because such workers could accumulate exposures (micrograms/m3-years) similar to those associated with excess risk in Hayes et al's cohort. Moreover, many current workers are estimated to be exposed to levels above the PEL. Further exploration of the dose-response relationship for chromium carcinogenesis is indicated."
13988,Bhargava et al. 1983,Study of an analytical method for hexavalent chromium,"Four methods for determination of chromium ions were compared. Five groups of filters were prepared with target values of 0.0, 0.5, 1.0, 10.0, and 50.0 micrograms (microg) of hexavalent chromium. Filters were randomly distributed to ten laboratories with explicit directions for analysis. Laboratories used either the OSHA draft method, which was extraction with sulfuric-acid (7664939), coupled with s-diphenylcarbazide (140227), and colorimetric determination; the American Welding Society (AWS) method, which was digestion with hot sodium-hydroxide (1310732) and sodium-carbonate (497198) and spectrophotometric determination; the NIOSH method, which was extraction with sulfuric-acid, addition of s-diphenylcarbazide, and absorbance compared to standards at 540 nanometers (nm); or the American Society for Testing and Materials (ASTM), which was extraction with sodium-hydroxide, addition of sulfuric-acid, addition of s-diphenylcarbazide, and absorbance compared to standards at 540nm. No significant change in the recoveries of chromium was found as a function of time. Chromium recovery was 60 to 70 percent using the OSHA method for concentrations below 10microg. The ASTM method provided recoveries of 87.8 (1microg added) to 101.7 percent; the AWS method provided recoveries of 93 (1microg added) to 104 percent. With the NIOSH method, recoveries were below 70 percent for amounts of 1microg or less, but 95.3 to 100.1 percent for greater amounts. Results from commercial laboratories were highly variable. The authors conclude that the use of the draft colorimetric diphenylcarbazide procedure with acid solubilization methods for hexavalent chromium analysis from sources other than chromic-acid (13530682) may be inappropriate.","Study of an analytical method for hexavalent chromium Abs: Four methods for determination of chromium ions were compared. Five groups of filters were prepared with target values of 0.0, 0.5, 1.0, 10.0, and 50.0 micrograms (microg) of hexavalent chromium. Filters were randomly distributed to ten laboratories with explicit directions for analysis. Laboratories used either the OSHA draft method, which was extraction with sulfuric-acid (7664939), coupled with s-diphenylcarbazide (140227), and colorimetric determination; the American Welding Society (AWS) method, which was digestion with hot sodium-hydroxide (1310732) and sodium-carbonate (497198) and spectrophotometric determination; the NIOSH method, which was extraction with sulfuric-acid, addition of s-diphenylcarbazide, and absorbance compared to standards at 540 nanometers (nm); or the American Society for Testing and Materials (ASTM), which was extraction with sodium-hydroxide, addition of sulfuric-acid, addition of s-diphenylcarbazide, and absorbance compared to standards at 540nm. No significant change in the recoveries of chromium was found as a function of time. Chromium recovery was 60 to 70 percent using the OSHA method for concentrations below 10microg. The ASTM method provided recoveries of 87.8 (1microg added) to 101.7 percent; the AWS method provided recoveries of 93 (1microg added) to 104 percent. With the NIOSH method, recoveries were below 70 percent for amounts of 1microg or less, but 95.3 to 100.1 percent for greater amounts. Results from commercial laboratories were highly variable. The authors conclude that the use of the draft colorimetric diphenylcarbazide procedure with acid solubilization methods for hexavalent chromium analysis from sources other than chromic-acid (13530682) may be inappropriate."
13983,Aaseth et al. 1982,Uptake of 51Cr-chromate by human erythrocytes - a role of glutathione,"Hexavalent chromium (Cr-VI), as Na2CrO4 in an aqueous solution, was reduced rapidly ot the trivalent form (Cr-III) in the presence of glutathione, GSH (0.3-3.0 mM). Such GSH-dependent reduction Cr-VI can take place in the cytosolic space of Cr-VI-exposed cells, since GSH is found in reactive concentrations in this compartment. The reduction makes chromium essentially impermeable through the cell membrane, explaining the observation that Cr-VI, when added to red cell suspensions, is bound quantitatively intracellularly after a few hours. Diethylmaleate conjugation of the SH-group of the intracellular GSH preventing the oxidation to GSSG, lowered the chromium-uptake significantly, showing that reduced GSH plays a role for the chromium binding. In healthy red cells chromium is partially bound to haemoglobin and partially to small molecular weight substances, probably in the trivalent form. This intracellular chromium cannot be removed to the extracellular space by addition of chelating agents as long as the cell membrane is intact.","Uptake of 51Cr-chromate by human erythrocytes - a role of glutathione Abs: Hexavalent chromium (Cr-VI), as Na2CrO4 in an aqueous solution, was reduced rapidly ot the trivalent form (Cr-III) in the presence of glutathione, GSH (0.3-3.0 mM). Such GSH-dependent reduction Cr-VI can take place in the cytosolic space of Cr-VI-exposed cells, since GSH is found in reactive concentrations in this compartment. The reduction makes chromium essentially impermeable through the cell membrane, explaining the observation that Cr-VI, when added to red cell suspensions, is bound quantitatively intracellularly after a few hours. Diethylmaleate conjugation of the SH-group of the intracellular GSH preventing the oxidation to GSSG, lowered the chromium-uptake significantly, showing that reduced GSH plays a role for the chromium binding. In healthy red cells chromium is partially bound to haemoglobin and partially to small molecular weight substances, probably in the trivalent form. This intracellular chromium cannot be removed to the extracellular space by addition of chelating agents as long as the cell membrane is intact."
13981,Yamamoto et al. 1981,"A low-molecular-weight, chromium-binding substance in mammals","HEEP COPYRIGHT: BIOL ABS. Male mice (dd) were injected i.p. with a single dose of potassium dichromate (50 or 200 mumol Cr/kg). Assay of Cr in organs and their soluble fractions showed that most Cr was found in the cytosol. Along with high MW compounds of Cr, a low MW Cr compound was identified by Sephadex chromatography of liver supernatants. Its content increased soon after injection and it persisted as long as 7 days, in contrast to the rapid disappearance of high MW compounds. Examination of urine and feces by molecular sieve experiments revealed a similar low MW Cr compound in the same fraction of the eluate as that of liver. A significant amount of Cr was found in the same elution fraction of plasma at 2 h although it was not clearly evident at 15 min. A low MW, Cr binding substance (LMCr) was formed in liver which participated in retention and excretion of Cr in the body. LMCr was partially purified from livers of rabbits injected i.v. with potassium dichromate (200 mumol Cr/kg) by a combination of ethanol extraction and DEAE-Sephadex, Sephadex gel and TLC, followed by paper electrophoresis. Based on its demonstrated characteristics, LMCr was an anionic organic complex which contained Cr (III), amino acids and some other UV absorbable components. It was separated into 2 subfractions with MW of","A low-molecular-weight, chromium-binding substance in mammals Abs: HEEP COPYRIGHT: BIOL ABS. Male mice (dd) were injected i.p. with a single dose of potassium dichromate (50 or 200 mumol Cr/kg). Assay of Cr in organs and their soluble fractions showed that most Cr was found in the cytosol. Along with high MW compounds of Cr, a low MW Cr compound was identified by Sephadex chromatography of liver supernatants. Its content increased soon after injection and it persisted as long as 7 days, in contrast to the rapid disappearance of high MW compounds. Examination of urine and feces by molecular sieve experiments revealed a similar low MW Cr compound in the same fraction of the eluate as that of liver. A significant amount of Cr was found in the same elution fraction of plasma at 2 h although it was not clearly evident at 15 min. A low MW, Cr binding substance (LMCr) was formed in liver which participated in retention and excretion of Cr in the body. LMCr was partially purified from livers of rabbits injected i.v. with potassium dichromate (200 mumol Cr/kg) by a combination of ethanol extraction and DEAE-Sephadex, Sephadex gel and TLC, followed by paper electrophoresis. Based on its demonstrated characteristics, LMCr was an anionic organic complex which contained Cr (III), amino acids and some other UV absorbable components. It was separated into 2 subfractions with MW of"
10706,Olshan and  Faustman 1993,Male-mediated developmental toxicity,"National Institute of Environmental Health Sciences; Charles A. Dana Foundation. CONCLUSIONS: A MULTIDISCIPLINARY PERSPECTIVE: This review has presented information from both the animal and human literature of chemical and radiation-induced, male-mediated developmental toxicity. Unfortunately, both literatures are plagued with incomplete reports characterized either by biases, incomplete exposure assessments, or small numbers of experimental units to evaluate. Nevertheless, enough scientific information exists to suggest potential associations and mechanisms for both genetic and epigenetic mechanisms of action. Many (several) chemicals and other agents can induce mutations in the male germ cell and produce such outcomes as pregnancy loss, growth retardation, congenital anomalies, tumors, and neurobehavioral effects. As data continue to accumulate, examination of patterns relating to concordance among test system results, relationship between chemical structure and test results, germ cell stage specificity, and the specific nature of the genetic damage induced will be possible. Initial epidemiologic studies have identified certain paternal environmental, occupational, and lifestyle exposures that may increase the risk of pregnancy loss, preterm delivery, intrauterine growth retardation, birth defects, and childhood cancer. At present many of these findings await confirmation. More work is needed to evaluate and attempt to synthesize these findings, describe limitations, and propose potentially fruitful areas of further investigation. In addition, evaluation of epidemiologic studies should incorporate consideration of laboratory results and biologic models. Direct comparison with results of laboratory studies is difficult at present since the epidemiologic findings mostly involve association with a broad array of occupations and industries. This makes it difficult to directly compare specific agents listed in Table I with exposures listed in Table 2. The public health relevance of male-mediated developmental toxicity currently cannot be fully evaluated. More basic experimental animal and human data are needed, as well as elaboration of possible mechanisms. At a fundamental level the available data do indicate that paternal exposures can produce adverse developmental outcomes. The developmental endpoints discussed here are of public health importance; given that most do not have a known etiology, male-mediated pathways should not be ignored. Hopefully, this review will stimulate the combined community of toxicologists, epidemiologists, and geneticists to evaluate further this pathway of toxicity.","Male-mediated developmental toxicity Abs: National Institute of Environmental Health Sciences; Charles A. Dana Foundation. CONCLUSIONS: A MULTIDISCIPLINARY PERSPECTIVE: This review has presented information from both the animal and human literature of chemical and radiation-induced, male-mediated developmental toxicity. Unfortunately, both literatures are plagued with incomplete reports characterized either by biases, incomplete exposure assessments, or small numbers of experimental units to evaluate. Nevertheless, enough scientific information exists to suggest potential associations and mechanisms for both genetic and epigenetic mechanisms of action. Many (several) chemicals and other agents can induce mutations in the male germ cell and produce such outcomes as pregnancy loss, growth retardation, congenital anomalies, tumors, and neurobehavioral effects. As data continue to accumulate, examination of patterns relating to concordance among test system results, relationship between chemical structure and test results, germ cell stage specificity, and the specific nature of the genetic damage induced will be possible. Initial epidemiologic studies have identified certain paternal environmental, occupational, and lifestyle exposures that may increase the risk of pregnancy loss, preterm delivery, intrauterine growth retardation, birth defects, and childhood cancer. At present many of these findings await confirmation. More work is needed to evaluate and attempt to synthesize these findings, describe limitations, and propose potentially fruitful areas of further investigation. In addition, evaluation of epidemiologic studies should incorporate consideration of laboratory results and biologic models. Direct comparison with results of laboratory studies is difficult at present since the epidemiologic findings mostly involve association with a broad array of occupations and industries. This makes it difficult to directly compare specific agents listed in Table I with exposures listed in Table 2. The public health relevance of male-mediated developmental toxicity currently cannot be fully evaluated. More basic experimental animal and human data are needed, as well as elaboration of possible mechanisms. At a fundamental level the available data do indicate that paternal exposures can produce adverse developmental outcomes. The developmental endpoints discussed here are of public health importance; given that most do not have a known etiology, male-mediated pathways should not be ignored. Hopefully, this review will stimulate the combined community of toxicologists, epidemiologists, and geneticists to evaluate further this pathway of toxicity."
9213,Cohen et al. 1997,Pulmonary retention and distribution of inhaled chromium: effects of particle solubility and coexposure to ozone,"Soluble and insoluble chromium ( Cr) agents are concomitantly released with ozone (O3) during welding. Although pulmonary implications from exposure to each agent individually have been investigated, the effects from simultaneous exposure, as occurs under actual working conditions, are unclear. To investigate the retention/distribution of inhaled Cr, male F-344 rats were exposed nose-only to atmospheres containing soluble potassium chromate (K2CrO4) or O3, either alone or in combination, at 360 ?g Cr/m3 and 0.3 ppm O3. In a second phase of the study, insoluble barium chromate (BaCrO4) was used in place of K2CrO4. Rats were exposed for 5 h/day, 5 days/wk for 2 or 4 wk. One day after the final exposure, rats were euthanized and their lungs either removed intact or lavaged for quantitation of tissue-, lavaged cell–, and acellular lavage fluid–associated Cr. In general, rats inhaling insoluble Cr had greater total lung Cr burdens than did rats exposed to soluble Cr. Simultaneous inhalation of O3 and K2CrO4 led to reduced lung Cr levels compared to those in rats receiving K2CrO4 only; with BaCrO4, coexposure to O3 resulted in increased lung BaCrO4 levels compared to BaCrO4 alone. Particle solubility also affected Cr levels in lavageable cells, with those from rats inhaling BaCrO4 alone or BaCrO4 + O3 consistently having greater burdens than their K2CrO4 counterparts; the presence of O3 itself had no effect upon cell Cr levels when either compound was used. Solubility-dependent differences were also apparent in acellular lavage fluid, with Cr levels initially being greater in fluids from rats inhaling K2CrO4 alone; as exposures continued, these burdens became greater in the rats inhaling BaCrO4 alone. Although inhalation of either Cr/O3 mixture yielded significant differences in fluid Cr levels, the presence of O3 did lead to reductions in levels compared to those in rats inhaling either Cr agent alone. In postlavage lung tissue, there were time-dependent increases in Cr levels in rats from all exposure groups; however, the most dramatic increase occurred with rats exposed to BaCrO4 + O3. Lastly, while significant solubility-dependent differences in the relative distribution of Cr among the three pulmonary compartments were discerned, a specific effect attributable to O3 itself was not evident. The results of this study indicate that Cr retention and distribution within the lungs, as well as any effect from coexposure to O3, are modulated by the solubility of the inhaled Cr particles.","Pulmonary retention and distribution of inhaled chromium: effects of particle solubility and coexposure to ozone Abs: Soluble and insoluble chromium ( Cr) agents are concomitantly released with ozone (O3) during welding. Although pulmonary implications from exposure to each agent individually have been investigated, the effects from simultaneous exposure, as occurs under actual working conditions, are unclear. To investigate the retention/distribution of inhaled Cr, male F-344 rats were exposed nose-only to atmospheres containing soluble potassium chromate (K2CrO4) or O3, either alone or in combination, at 360 ?g Cr/m3 and 0.3 ppm O3. In a second phase of the study, insoluble barium chromate (BaCrO4) was used in place of K2CrO4. Rats were exposed for 5 h/day, 5 days/wk for 2 or 4 wk. One day after the final exposure, rats were euthanized and their lungs either removed intact or lavaged for quantitation of tissue-, lavaged cell–, and acellular lavage fluid–associated Cr. In general, rats inhaling insoluble Cr had greater total lung Cr burdens than did rats exposed to soluble Cr. Simultaneous inhalation of O3 and K2CrO4 led to reduced lung Cr levels compared to those in rats receiving K2CrO4 only; with BaCrO4, coexposure to O3 resulted in increased lung BaCrO4 levels compared to BaCrO4 alone. Particle solubility also affected Cr levels in lavageable cells, with those from rats inhaling BaCrO4 alone or BaCrO4 + O3 consistently having greater burdens than their K2CrO4 counterparts; the presence of O3 itself had no effect upon cell Cr levels when either compound was used. Solubility-dependent differences were also apparent in acellular lavage fluid, with Cr levels initially being greater in fluids from rats inhaling K2CrO4 alone; as exposures continued, these burdens became greater in the rats inhaling BaCrO4 alone. Although inhalation of either Cr/O3 mixture yielded significant differences in fluid Cr levels, the presence of O3 did lead to reductions in levels compared to those in rats inhaling either Cr agent alone. In postlavage lung tissue, there were time-dependent increases in Cr levels in rats from all exposure groups; however, the most dramatic increase occurred with rats exposed to BaCrO4 + O3. Lastly, while significant solubility-dependent differences in the relative distribution of Cr among the three pulmonary compartments were discerned, a specific effect attributable to O3 itself was not evident. The results of this study indicate that Cr retention and distribution within the lungs, as well as any effect from coexposure to O3, are modulated by the solubility of the inhaled Cr particles."
8853,Kubinski et al. 1981,DNA-cell-binding (DCB) assay for suspected carcinogens and mutagens,"This report describes a novel technique for screening potential carcinogens and mutagens. The DNA-cell-binding (DCB) assay is based on earlier observations which indicated that DNA and other nucleic acids exposed to active carcinogens strongly react with other macromolecules, producing nucleic acid--nucleic acid and nucleic acid--protein adducts. The latter group of adducts included complexes with proteins present in both prokaryotic and eukaryotic cell membranes. Increased attachment of DNA to the intact bacterial and animal cells was seen in the presence of active carcinogens or carcinogens activated by extracts from mouse and rat livers. We have conducted a survey of almost 280 chemicals including 130 with known carcinogenic potential (i.e., either known carcinogens or known non-carcinogens). The DCB test and animal assays agreed in abut 96% of cases. Thus, as a predictor of potential carcinogenicity, this assay compares favorably with other rapid methods currently in use. In this respect, the DCB assay is also superior to other techniques which measure the formation of macromolecular complexes, such as velocity centrifugation through sucrose gradients, gel electrophoresis, filtration through nitrocellulose filters, chromatography on methyl-esterified albumin, equilibrium density gradient centrifugation, etc. In the few cases for which the data were available, combining the results of DCB assays with the results of experiments in which the induction of DNA--protein adducts in living human cells in tissue culture has been measured by cold phenol extraction, the predictability was increased to 100%. We suggest that DCB assay should be used either alone or in combination with other rapid methods of carcinogen detection for screening industrial, environmental and other chemicals and chemical mixtures for their carcinogenic potential. Ways of further improving and simplifying the DCB tests are considered.","DNA-cell-binding (DCB) assay for suspected carcinogens and mutagens Abs: This report describes a novel technique for screening potential carcinogens and mutagens. The DNA-cell-binding (DCB) assay is based on earlier observations which indicated that DNA and other nucleic acids exposed to active carcinogens strongly react with other macromolecules, producing nucleic acid--nucleic acid and nucleic acid--protein adducts. The latter group of adducts included complexes with proteins present in both prokaryotic and eukaryotic cell membranes. Increased attachment of DNA to the intact bacterial and animal cells was seen in the presence of active carcinogens or carcinogens activated by extracts from mouse and rat livers. We have conducted a survey of almost 280 chemicals including 130 with known carcinogenic potential (i.e., either known carcinogens or known non-carcinogens). The DCB test and animal assays agreed in abut 96% of cases. Thus, as a predictor of potential carcinogenicity, this assay compares favorably with other rapid methods currently in use. In this respect, the DCB assay is also superior to other techniques which measure the formation of macromolecular complexes, such as velocity centrifugation through sucrose gradients, gel electrophoresis, filtration through nitrocellulose filters, chromatography on methyl-esterified albumin, equilibrium density gradient centrifugation, etc. In the few cases for which the data were available, combining the results of DCB assays with the results of experiments in which the induction of DNA--protein adducts in living human cells in tissue culture has been measured by cold phenol extraction, the predictability was increased to 100%. We suggest that DCB assay should be used either alone or in combination with other rapid methods of carcinogen detection for screening industrial, environmental and other chemicals and chemical mixtures for their carcinogenic potential. Ways of further improving and simplifying the DCB tests are considered."
8845,Kada et al. 1980,Screening of environmental chemical mutagens by the rec-assay system with Bacillus subtilis,,Screening of environmental chemical mutagens by the rec-assay system with Bacillus subtilis Abs: 
8682,Mason and  Edwards 1989,"Acute toxicity of combinations of sodium dichromate, sodium arsenate and copper sulphate in the rat","1. The intraperitoneal treatment of adult male Wistar rats with various combinations of low doses of sodium dichromate (5 mg/kg), sodium arsenate (25 mg/kg) and copper sulphate (5.9 mg/kg) tended to counteract the inherent acute toxicity of each compound. 2. The co-administration of low doses of one or more of the test compounds with a high dose of sodium dichromate (35 mg/kg), sodium arsenate (90 mg/kg) or copper sulphate (23.5 mg/kg) resulted in a significant increase in acute toxicity in comparison with that produced by the administration of high doses of dichromate, arsenate or Cu2+ alone.","Acute toxicity of combinations of sodium dichromate, sodium arsenate and copper sulphate in the rat Abs: 1. The intraperitoneal treatment of adult male Wistar rats with various combinations of low doses of sodium dichromate (5 mg/kg), sodium arsenate (25 mg/kg) and copper sulphate (5.9 mg/kg) tended to counteract the inherent acute toxicity of each compound. 2. The co-administration of low doses of one or more of the test compounds with a high dose of sodium dichromate (35 mg/kg), sodium arsenate (90 mg/kg) or copper sulphate (23.5 mg/kg) resulted in a significant increase in acute toxicity in comparison with that produced by the administration of high doses of dichromate, arsenate or Cu2+ alone."
8511,Sunderman 1976,"A review of the carcinogenicities of nickel, chromium and arsenic compounds in man and animals","Increased incidences of cancers of the respiratory tract have been reported among (a) workers in nickel refineries; (b) industrial workers who have been engaged in production of chromates or in processing of chrome pigments; and (c) workers who have had diverse occupational exposures to arsenic compounds (metallurgical, chemical and agricultural workers). Human subjects who have developed clinical manifestations of arsenicalism as a result of environmental, occupational or iatrogenic exposures have been reported to have increased incidences of cancers of the skin and possibly of internal organs. Certain nickel and chromium compounds (e.g., nickel subsulfide and calcium chromate) that have been administered to rodents by parenteral or respiratory routes have induced cancers at the sites of deposition. Experimental induction of cancers in animals has not been reported as a consequence of administration of arsenic compounds.","A review of the carcinogenicities of nickel, chromium and arsenic compounds in man and animals Abs: Increased incidences of cancers of the respiratory tract have been reported among (a) workers in nickel refineries; (b) industrial workers who have been engaged in production of chromates or in processing of chrome pigments; and (c) workers who have had diverse occupational exposures to arsenic compounds (metallurgical, chemical and agricultural workers). Human subjects who have developed clinical manifestations of arsenicalism as a result of environmental, occupational or iatrogenic exposures have been reported to have increased incidences of cancers of the skin and possibly of internal organs. Certain nickel and chromium compounds (e.g., nickel subsulfide and calcium chromate) that have been administered to rodents by parenteral or respiratory routes have induced cancers at the sites of deposition. Experimental induction of cancers in animals has not been reported as a consequence of administration of arsenic compounds."
8504,Singh 1983,Induction of reverse mutation and mitotic gene conversion by some metal compounds in Saccharomyces cerevisiae,,Induction of reverse mutation and mitotic gene conversion by some metal compounds in Saccharomyces cerevisiae Abs: 
8484,Ridgway and  Karnofsky 1952,The effects of metals on the chick embryo: toxicity and production of abnormalities in development,"The effects of 54 elements on the development of the chick embryo were examined. Test agents were injected either into the yolk or onto the chorioallantoic membrane (CAM) of 4 or 8 day old embryos at a volume of 0.05 to 0.2 cubic centimeters. Preliminary toxicity tests were performed in 4 day embryos to determine the median lethal dose (LD50). Toxicity experiments were continued until day 18 of incubation. Embryos were killed, weighed, and examined for abnormalities. Factors relating to toxicity were related to the egg, the state and properties of the injected chemicals, and distribution and metabolism of the injected chemical. Values for LD50 ranged from 0.02 for arsenic (7440382) and 0.03 for selenium (7782492), to greater than 20 for gold (7440575) and barium (7440393). Elements were divided into four classes depending on general effects. Boron (7440428) and elements of its class showed the same LD50 irrespective of age or route of administration. Nickel (7440020) exemplified a group which showed decreased toxicity at 8 days relative to 4 days when injected into the yolk sac but not via the CAM. Lead (7439921) and other allied elements were most toxic at 4 days, and less toxic at 8 days regardless of route. Elements in the group containing barium were more toxic by CAM, a pattern shown by 50 percent of the elements tested. Thallium (7440280), chromium (7440473), lead, cobalt (7440484), boron, arsenic, rhodium (7440166), barium, and selenium showed specific and reproducible effects on embryonic development, ranging from achondroplasia to bizarre abnormalities and stunting. The authors conclude that some elements induce a characteristic effect on the embryo when given at the proper period of development.","The effects of metals on the chick embryo: toxicity and production of abnormalities in development Abs: The effects of 54 elements on the development of the chick embryo were examined. Test agents were injected either into the yolk or onto the chorioallantoic membrane (CAM) of 4 or 8 day old embryos at a volume of 0.05 to 0.2 cubic centimeters. Preliminary toxicity tests were performed in 4 day embryos to determine the median lethal dose (LD50). Toxicity experiments were continued until day 18 of incubation. Embryos were killed, weighed, and examined for abnormalities. Factors relating to toxicity were related to the egg, the state and properties of the injected chemicals, and distribution and metabolism of the injected chemical. Values for LD50 ranged from 0.02 for arsenic (7440382) and 0.03 for selenium (7782492), to greater than 20 for gold (7440575) and barium (7440393). Elements were divided into four classes depending on general effects. Boron (7440428) and elements of its class showed the same LD50 irrespective of age or route of administration. Nickel (7440020) exemplified a group which showed decreased toxicity at 8 days relative to 4 days when injected into the yolk sac but not via the CAM. Lead (7439921) and other allied elements were most toxic at 4 days, and less toxic at 8 days regardless of route. Elements in the group containing barium were more toxic by CAM, a pattern shown by 50 percent of the elements tested. Thallium (7440280), chromium (7440473), lead, cobalt (7440484), boron, arsenic, rhodium (7440166), barium, and selenium showed specific and reproducible effects on embryonic development, ranging from achondroplasia to bizarre abnormalities and stunting. The authors conclude that some elements induce a characteristic effect on the embryo when given at the proper period of development."
7593,Jelovsek et al. 1989,Prediction of risk for human developmental toxicity: How important are animal studies for hazard identification?,BIOSIS COPYRIGHT: BIOL ABS. RRM ANIMAL MODEL PRIMATE HAMSTER RAT MUTAGENICITY FUNCTIONAL TERATOLOGIC TOXICITY EMBRYOTOXICITY CARCINOGENESIS CHEMICAL TOXICITY,Prediction of risk for human developmental toxicity: How important are animal studies for hazard identification? Abs: BIOSIS COPYRIGHT: BIOL ABS. RRM ANIMAL MODEL PRIMATE HAMSTER RAT MUTAGENICITY FUNCTIONAL TERATOLOGIC TOXICITY EMBRYOTOXICITY CARCINOGENESIS CHEMICAL TOXICITY
7501,Zimmering et al. 1985,Chemical mutagenesis testing in Drosophila. II. Results of 20 coded compounds tested for the National Toxicology Program,"Results are presented from mutagenesis testing in Drosophila of 20 coded compounds. Two compounds were positive in the sex-linked recessive lethal test, and two were inconclusive. The positive compounds were calcium chromate in adult feeding experiments and ferrocene after adult injection. The two inconclusive compounds were 2,4-diaminophenol dihydrochloride and hexachlorocyclopentadiene. Compounds that produced a positive response were assayed for chromosome breakage using the conventional translocation test. Calcium chromate was negative in the translocation test, and ferrocene was positive. Many of the test compounds were poorly soluble in water, raising questions regarding the effective concentration to which the flies were exposed.","Chemical mutagenesis testing in Drosophila. II. Results of 20 coded compounds tested for the National Toxicology Program Abs: Results are presented from mutagenesis testing in Drosophila of 20 coded compounds. Two compounds were positive in the sex-linked recessive lethal test, and two were inconclusive. The positive compounds were calcium chromate in adult feeding experiments and ferrocene after adult injection. The two inconclusive compounds were 2,4-diaminophenol dihydrochloride and hexachlorocyclopentadiene. Compounds that produced a positive response were assayed for chromosome breakage using the conventional translocation test. Calcium chromate was negative in the translocation test, and ferrocene was positive. Many of the test compounds were poorly soluble in water, raising questions regarding the effective concentration to which the flies were exposed."
6701,Bostrom et al. 1994,Human exposure to urban air pollution,"This study deals with some methods of making human exposure estimates, aimed at describing the human exposure for selected air pollutants in Sweden that are suspected carcinogens. Nitrogen oxides (NO2) have been chosen as an indicator substance for estimating the concentration of the urban plume. Earlier investigations have shown that the traffic in Swedish cities contributes around 85% to the measured NO2 concentrations, and that most of the mutagenicity in urban air originates from traffic. The first section of this paper describes measurements in Stockholm of some unregulated light hydrocarbons, such as ethene, ethyne, propane, propene, butane, and isobutane. In addition, measurements of some volatile aromatic hydrocarbons are presented. Simultaneous measurements of carbon monoxide (CO) were made. The ratios between CO and the individual specific compounds were determined by linear regression analysis. By analysis of relationships between CO and NO2, NO2 concentrations can be used as a tracer to describe the exposure for these specific compounds. NO2 are considered to be a better tracer than CO, because NO2 or NO2 values exist for many places over a long time, while CO is measured mostly in streets with high concentrations. At low concentrations, instruments that measure normal CO levels give no detectable signals. Through use of atmospheric dispersion models and models that describe how people live and work in urban areas it has been possible to describe the average exposure to NO2 in cities of different sizes. The exposure to NO2 for people living in the countryside has also been estimated. In this way, it has been possible to calculate the average exposure dose for NO2 for the Swedish population. This figure is 23 micrograms/m3. By use of the relationships between NO2 and specific compounds the average dose has been calculated for the following compounds: polyaromatic compounds (PAH); ethene, propene, and butadiene; benzene, toluene, and xylene; formaldehyde and actaldehyde; nickel, chromium (VI), arsenic, and cadmium; asbestos; and silicon.","Human exposure to urban air pollution Abs: This study deals with some methods of making human exposure estimates, aimed at describing the human exposure for selected air pollutants in Sweden that are suspected carcinogens. Nitrogen oxides (NO2) have been chosen as an indicator substance for estimating the concentration of the urban plume. Earlier investigations have shown that the traffic in Swedish cities contributes around 85% to the measured NO2 concentrations, and that most of the mutagenicity in urban air originates from traffic. The first section of this paper describes measurements in Stockholm of some unregulated light hydrocarbons, such as ethene, ethyne, propane, propene, butane, and isobutane. In addition, measurements of some volatile aromatic hydrocarbons are presented. Simultaneous measurements of carbon monoxide (CO) were made. The ratios between CO and the individual specific compounds were determined by linear regression analysis. By analysis of relationships between CO and NO2, NO2 concentrations can be used as a tracer to describe the exposure for these specific compounds. NO2 are considered to be a better tracer than CO, because NO2 or NO2 values exist for many places over a long time, while CO is measured mostly in streets with high concentrations. At low concentrations, instruments that measure normal CO levels give no detectable signals. Through use of atmospheric dispersion models and models that describe how people live and work in urban areas it has been possible to describe the average exposure to NO2 in cities of different sizes. The exposure to NO2 for people living in the countryside has also been estimated. In this way, it has been possible to calculate the average exposure dose for NO2 for the Swedish population. This figure is 23 micrograms/m3. By use of the relationships between NO2 and specific compounds the average dose has been calculated for the following compounds: polyaromatic compounds (PAH); ethene, propene, and butadiene; benzene, toluene, and xylene; formaldehyde and actaldehyde; nickel, chromium (VI), arsenic, and cadmium; asbestos; and silicon."
5457,Stern et al. 1998,The association of chromium in household dust with urinary chromium in residences adjacent to chromate production waste sites,"#Several previous studies of exposure to chromium waste in New Jersey have shown that Cr levels are elevated in household dust in homes adjacent to waste sites and that Cr levels in the urine of residents near sites are also elevated compared to control populations. It has not been possible until now, however, to examine these external and internal measures of exposure together in a large population to determine whether the external exposure is predictive of the internal exposure. We investigated the relationship between various adjusted and unadjusted measures of spot urine Cr concentration and household dust Cr from residents and residences adjacent to known Cr waste sites. Statistically significant bivariate relationships were found between log-transformed urine Cr concentration and Cr dust concentration (micrograms of Cr per gram of dust) but not Cr dust loading (nanogram Cr per square centimeter). Log-transformed urine concentration was used as the dependent variable in multiple regression analysis of the total population (n = 329), the population ½=10 years old (n = 67), and the population >10 years old (n = 262), with Cr dust concentration as a mandatory independent variable. Other potential direct influences on urine Cr were investigated as potential confounders of this relationship. In the final models for the entire population and those ½=10 years old, but not for those >10 years old, Cr dust concentration remalned significant. This suggests that exposure of young children to Cr in household dust accounts for much of the relationship in the entire population.","The association of chromium in household dust with urinary chromium in residences adjacent to chromate production waste sites Abs: #Several previous studies of exposure to chromium waste in New Jersey have shown that Cr levels are elevated in household dust in homes adjacent to waste sites and that Cr levels in the urine of residents near sites are also elevated compared to control populations. It has not been possible until now, however, to examine these external and internal measures of exposure together in a large population to determine whether the external exposure is predictive of the internal exposure. We investigated the relationship between various adjusted and unadjusted measures of spot urine Cr concentration and household dust Cr from residents and residences adjacent to known Cr waste sites. Statistically significant bivariate relationships were found between log-transformed urine Cr concentration and Cr dust concentration (micrograms of Cr per gram of dust) but not Cr dust loading (nanogram Cr per square centimeter). Log-transformed urine concentration was used as the dependent variable in multiple regression analysis of the total population (n = 329), the population ½=10 years old (n = 67), and the population >10 years old (n = 262), with Cr dust concentration as a mandatory independent variable. Other potential direct influences on urine Cr were investigated as potential confounders of this relationship. In the final models for the entire population and those ½=10 years old, but not for those >10 years old, Cr dust concentration remalned significant. This suggests that exposure of young children to Cr in household dust accounts for much of the relationship in the entire population."
4286,Glaser et al. 1990,Investigation of irritating properties of inhaled Cr(VI) with possible influence on its carcinogenic action,,Investigation of irritating properties of inhaled Cr(VI) with possible influence on its carcinogenic action Abs: 
3517,Snow 1991,A possible role for chromium(III) in genotoxicity,,A possible role for chromium(III) in genotoxicity Abs: 
1576,Kilburn 1999,Neurobehavioral and respiratory findings in jet engine repair workers: a comparison of exposed and unexposed volunteers,"Workers repairing jet engines had respiratory, rheumatic, and neurobehavioral symptoms. They had welded and ground stainless steel parts using hard metal tools and cleaned metal with chlorinated and fluorinated organic solvents. We compared 154 workers and 112 unexposed subjects, all volunteers of similar ages and with similar educational levels, for abnormalities on chest radiographs, spirometric measurements, and questionnaires. Also appraised were performance of reaction time, balance, blink reflex latency, color discrimination, Culture Fair, vocabulary, slotted pegboard, trail making A and B, profile of mood states (POMS), and frequencies of 35 symptoms. Compared to unexposed subjects, workers had significantly more respiratory symptoms but no differences in pulmonary function. They had significantly prolonged simple and choice reaction time (P<0.0001), and abnormal balance with eyes open and eyes closed (P<0.0001), and abnormal color discrimination. Blink reflex latency was abnormal in both exposed workers and in local unexposed compared to other reference groups. Focus of the inquiry on lung disease helped ensure that for neurobehavioral tests confounding factors were minimal and known biases were small. We tentatively attribute the neurobehavioral impairments and increased symptom frequencies to chlorinated solvent exposure. Excessive respiratory symptoms are attributed to welding stainless steel combined with cigarette smoking. Specifically, manganese exposure may have affected the respiratory and the central nervous systems.","Neurobehavioral and respiratory findings in jet engine repair workers: a comparison of exposed and unexposed volunteers Abs: Workers repairing jet engines had respiratory, rheumatic, and neurobehavioral symptoms. They had welded and ground stainless steel parts using hard metal tools and cleaned metal with chlorinated and fluorinated organic solvents. We compared 154 workers and 112 unexposed subjects, all volunteers of similar ages and with similar educational levels, for abnormalities on chest radiographs, spirometric measurements, and questionnaires. Also appraised were performance of reaction time, balance, blink reflex latency, color discrimination, Culture Fair, vocabulary, slotted pegboard, trail making A and B, profile of mood states (POMS), and frequencies of 35 symptoms. Compared to unexposed subjects, workers had significantly more respiratory symptoms but no differences in pulmonary function. They had significantly prolonged simple and choice reaction time (P<0.0001), and abnormal balance with eyes open and eyes closed (P<0.0001), and abnormal color discrimination. Blink reflex latency was abnormal in both exposed workers and in local unexposed compared to other reference groups. Focus of the inquiry on lung disease helped ensure that for neurobehavioral tests confounding factors were minimal and known biases were small. We tentatively attribute the neurobehavioral impairments and increased symptom frequencies to chlorinated solvent exposure. Excessive respiratory symptoms are attributed to welding stainless steel combined with cigarette smoking. Specifically, manganese exposure may have affected the respiratory and the central nervous systems."
861,Cohen et al. 1998,Immunotoxicologic effects of inhaled chromium: role of particle solubility and co-exposure to ozone,"National Institute of Environmental Health Sciences. Soluble and insoluble hexavalent chromium (Cr6+) agents are concomitantly released with ozone (O3) during welding. Although pulmonary/immunologic implications from exposure to each agent individually have been investigated, the effects from simultaneous exposure, as occurs under actual working conditions, are unclear. To investigate immunomodulatory effects of inhaled Cr6+, F-344 rats were exposed for 5 h/day, 5 days/week for 2 or 4 weeks to atmospheres containing soluble potassium chromate (K2CrO4) or insoluble barium chromate (BaCrO4), each alone at 360 ""mu""g Cr/m3 or in combination with 0.3 ppm O3. One day after the final exposure, rats were euthanized, their lungs were lavaged, and pulmonary macrophages (PAM) were recovered for assessment of basal and inducible functions. Rats inhaling K2CrO4-containing atmospheres had greater levels of total recoverable cells, neutrophils, and monocytes in bronchopulmonary lavage compared to rats exposed to insoluble Cr6+ atmospheres, O3 alone, or air; these rats also had a reduced percentage of PAM, although total PAM levels remained unaffected. Although Cr exposure-related changes in PAM functionality were evident, any dependence upon Cr solubility was variable. K2CrO4-containing atmospheres modulated PAM-inducible interleukins-1 and -6, and tumor necrosis factor-a production to a greater degree than those containing BaCrO4. Conversely, BaCrO4-containing atmospheres affected PAM basal nitric oxide production and interferon-y-primed/zymosan-stimulated reactive oxygen intermediate production to a greater extent than did those containing K2CrO4. In none of the PAM assays did co-inhalation of O3 result in a modulation of the effects obtained with either Cr6+ compound itself. The results indicate that, while immunomodulatory effects of inhaled Cr6+ upon PAM are related to particle solubility, the co-inhalation of O3 apparently does not cause further modifications of the metal-induced effects.","Immunotoxicologic effects of inhaled chromium: role of particle solubility and co-exposure to ozone Abs: National Institute of Environmental Health Sciences. Soluble and insoluble hexavalent chromium (Cr6+) agents are concomitantly released with ozone (O3) during welding. Although pulmonary/immunologic implications from exposure to each agent individually have been investigated, the effects from simultaneous exposure, as occurs under actual working conditions, are unclear. To investigate immunomodulatory effects of inhaled Cr6+, F-344 rats were exposed for 5 h/day, 5 days/week for 2 or 4 weeks to atmospheres containing soluble potassium chromate (K2CrO4) or insoluble barium chromate (BaCrO4), each alone at 360 ""mu""g Cr/m3 or in combination with 0.3 ppm O3. One day after the final exposure, rats were euthanized, their lungs were lavaged, and pulmonary macrophages (PAM) were recovered for assessment of basal and inducible functions. Rats inhaling K2CrO4-containing atmospheres had greater levels of total recoverable cells, neutrophils, and monocytes in bronchopulmonary lavage compared to rats exposed to insoluble Cr6+ atmospheres, O3 alone, or air; these rats also had a reduced percentage of PAM, although total PAM levels remained unaffected. Although Cr exposure-related changes in PAM functionality were evident, any dependence upon Cr solubility was variable. K2CrO4-containing atmospheres modulated PAM-inducible interleukins-1 and -6, and tumor necrosis factor-a production to a greater degree than those containing BaCrO4. Conversely, BaCrO4-containing atmospheres affected PAM basal nitric oxide production and interferon-y-primed/zymosan-stimulated reactive oxygen intermediate production to a greater extent than did those containing K2CrO4. In none of the PAM assays did co-inhalation of O3 result in a modulation of the effects obtained with either Cr6+ compound itself. The results indicate that, while immunomodulatory effects of inhaled Cr6+ upon PAM are related to particle solubility, the co-inhalation of O3 apparently does not cause further modifications of the metal-induced effects."
